Sample records for psii charge separation

  1. Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

    NARCIS (Netherlands)

    Flameling, I.A.; Kromkamp, J.C.


    Quantum yields of photosystem II (PSII) charge separation (Phi(P)) and oxygen production (Phi(O2)) were determined by simultaneous measurements of oxygen production and variable fluorescence in four different aquatic microalgae representing three different taxonomic groups: the freshwater alga

  2. Quantum-coherent dynamics in photosynthetic charge separation revealed by wavelet analysis


    Romero, Elisabet; Prior, Javier; Chin, Alex W.; Morgan, Sarah E.; Novoderezhkin, Vladimir I.; Plenio, Martin B.; van Grondelle, Rienk


    Experimental/theoretical evidence for sustained vibration-assisted electronic (vibronic) coherence in the Photosystem II Reaction Center (PSII RC) indicates that photosynthetic solar-energy conversion might be optimized through the interplay of electronic and vibrational quantum dynamics. This evidence has been obtained by investigating the primary charge separation process in the PSII RC by two-dimensional electronic spectroscopy (2DES) and Redfield modeling of the experimental data. However...

  3. Quantum modeling of ultrafast photoinduced charge separation (United States)

    Rozzi, Carlo Andrea; Troiani, Filippo; Tavernelli, Ivano


    Phenomena involving electron transfer are ubiquitous in nature, photosynthesis and enzymes or protein activity being prominent examples. Their deep understanding thus represents a mandatory scientific goal. Moreover, controlling the separation of photogenerated charges is a crucial prerequisite in many applicative contexts, including quantum electronics, photo-electrochemical water splitting, photocatalytic dye degradation, and energy conversion. In particular, photoinduced charge separation is the pivotal step driving the storage of sun light into electrical or chemical energy. If properly mastered, these processes may also allow us to achieve a better command of information storage at the nanoscale, as required for the development of molecular electronics, optical switching, or quantum technologies, amongst others. In this Topical Review we survey recent progress in the understanding of ultrafast charge separation from photoexcited states. We report the state-of-the-art of the observation and theoretical description of charge separation phenomena in the ultrafast regime mainly focusing on molecular- and nano-sized solar energy conversion systems. In particular, we examine different proposed mechanisms driving ultrafast charge dynamics, with particular regard to the role of quantum coherence and electron-nuclear coupling, and link experimental observations to theoretical approaches based either on model Hamiltonians or on first principles simulations.

  4. Quantum modeling of ultrafast photoinduced charge separation. (United States)

    Rozzi, Carlo Andrea; Troiani, Filippo; Tavernelli, Ivano


    Phenomena involving electron transfer are ubiquitous in nature, photosynthesis and enzymes or protein activity being prominent examples. Their deep understanding thus represents a mandatory scientific goal. Moreover, controlling the separation of photogenerated charges is a crucial prerequisite in many applicative contexts, including quantum electronics, photo-electrochemical water splitting, photocatalytic dye degradation, and energy conversion. In particular, photoinduced charge separation is the pivotal step driving the storage of sun light into electrical or chemical energy. If properly mastered, these processes may also allow us to achieve a better command of information storage at the nanoscale, as required for the development of molecular electronics, optical switching, or quantum technologies, amongst others. In this Topical Review we survey recent progress in the understanding of ultrafast charge separation from photoexcited states. We report the state-of-the-art of the observation and theoretical description of charge separation phenomena in the ultrafast regime mainly focusing on molecular- and nano-sized solar energy conversion systems. In particular, we examine different proposed mechanisms driving ultrafast charge dynamics, with particular regard to the role of quantum coherence and electron-nuclear coupling, and link experimental observations to theoretical approaches based either on model Hamiltonians or on first principles simulations.

  5. Gravitomagnetic Separation of Bipolar Charged Martian Dust (United States)

    Arias, FJ


    In this work it is shown that magnetic anomalies on Mars can actually boost gravitational spatial separation of bipolar charged Martian dust. If so, these places are prone for high electrical activity and then formation of chemical process requiring electrical sparks.

  6. Energy storage device with large charge separation (United States)

    Holme, Timothy P.; Prinz, Friedrich B.; Iancu, Andrei


    High density energy storage in semiconductor devices is provided. There are two main aspects of the present approach. The first aspect is to provide high density energy storage in semiconductor devices based on formation of a plasma in the semiconductor. The second aspect is to provide high density energy storage based on charge separation in a p-n junction.

  7. Charged colloids at low ionic strength: macro- or microphase separation?


    Warren, Patrick B


    Phase separation in charged systems may involve the replacement of critical points by microphase separated states, or charge-density-wave states. A density functional theory for highly charged colloids at low ionic strength is developed to examine this possibility. It is found that the lower critical solution point is most susceptible to microphase separation. Moreover the tendency can be quantified, and related to the importance of small ion entropy in suppressing phase separation at low add...

  8. Charged porous membrane structures for separation of biomolecules

    NARCIS (Netherlands)

    Kopec, K.K.


    Thesis presents various membrane techniques for biomolecules separation. New charged membranes and new methods to introduce charge into the membranes are demonstrated. All chapters present characterization of the hollow fiber membranes produced via the immersion precipitation dry-wet spinning. Apart

  9. Charge renormalization and phase separation in colloidal suspensions


    Diehl, Alexandre; BARBOSA, Marcia C.; Levin, Yan


    We explore the effects of counterion condensation on fluid-fluid phase separation in charged colloidal suspensions. It is found that formation of double layers around the colloidal particles stabilizes suspensions against phase separation. Addition of salt, however, produces an instability which, in principle, can lead to a fluid-fluid separation. The instability, however, is so weak that it should be impossible to observe a fully equilibrated coexistence experimentally.

  10. Photoinduced charge separation and enzyme reactions in reversed micelles

    NARCIS (Netherlands)

    Verhaert, R.M.D.


    In this thesis the performance and coupling of two types of reaction, photoinduced charge separation and enzymatic conversion were studied in reversed micelles. Reversed micelles are 1 to 10 nm sized water droplets dispersed in an organic solution. The dispersant is a detergent (cationogenic,

  11. Separation of charge movement components in mammalian skeletal muscle fibres. (United States)

    Francini, F; Bencini, C; Piperio, C; Squecco, R


    1. Intramembrane charge movements, I(ICM), were measured in rat skeletal muscle fibres in response to voltage steps from a -90 mV holding potential to a wide test voltage range (-85 to 30 mV), using a double Vaseline-gap voltage-clamp technique. Solutions were designed to minimise ionic currents. Ca(2+) current was blocked by adding Cd(2+) (0.8 mM) to the external solution. In a subset of experiments Cd(2+) was omitted to determine which components of the charge movement best correlated with L-type Ca(2+) channel gating. 2. Detailed kinetic analysis of I(ICM) identified two major groups of charges. The first two components, designated Q(a) and Q(b), were the only charges moved by small depolarising steps. The second group of components, Q(c) and Q(d), showed a more positive voltage threshold, -35.6 +/- 2.0 mV, (n = 6) in external solution with Cd(2+), and -41.1 +/- 2.0 mV (n = 12) in external solution without Cd(2+). Notably, in external solution without Cd(2+) the voltage threshold of Ca(2+) current, I(Ca), activation had a similar value, being -38.1 +/- 2.4 mV. 3. The sum of three Boltzmann functions, Q(1), Q(2) and Q(3), showing progressively more positive transition voltages, could be fitted to charge versus voltage, Q(ICM)-V, plots. The three Boltzmann terms identified three charge components: Q(1) described the shallow voltage-dependent Q(a) and Q(b) charges, Q(2) and Q(3) described the steep voltage-dependent Q(c) and Q(d) charges. 4. In external solution without Cd(2+) the charge kinetics changed: a slow decaying phase was replaced by a pronounced delayed hump. Moreover, the transition voltages of the individual steady-state charge components were shifted towards negative potentials (from 6.3 to 8.2 mV). Nevertheless, the overall charge and steepness factors were conserved. 5. In conclusion, these experiments allowed a clear separation of four components of intramembrane charge movements in rat skeletal muscle, showing that there are no fundamental

  12. Accumulative electron transfer: multiple charge separation in artificial photosynthesis. (United States)

    Karlsson, Susanne; Boixel, Julien; Pellegrin, Yann; Blart, Errol; Becker, Hans-Christian; Odobel, Fabrice; Hammarström, Leif


    To achieve artificial photosynthesis it is necessary to couple the single-electron event of photoinduced charge separation with the multi-electron reactions of fuel formation and water splitting. Therefore, several rounds of light-induced charge separation are required to accumulate enough redox equivalents at the catalytic sites for the target chemistry to occur, without any sacrificial donors or acceptors other than the catalytic substrates. Herein, we discuss the challenges of such accumulative electron transfer in molecular systems. We present a series of closely related systems base on a Ru(II)-polypyridine photosensitizer with appended triaryl-amine or oligo-triaryl-amine donors, linked to nanoporous TiO2 as the acceptor. One of the systems, based on dye 4, shows efficient accumulative electron transfer in high overall yield resulting in the formation of a two-electron charge-separated state upon successive excitation by two photons. In contrast, the other systems do not show accumulative electron transfer because of different competing reactions. This illustrates the difficulties in designing successful systems for this still largely unexplored type of reaction scheme.

  13. Long-lived charge separation and applications in artificial photosynthesis. (United States)

    Fukuzumi, Shunichi; Ohkubo, Kei; Suenobu, Tomoyoshi


    Researchers have long been interested in replicating the reactivity that occurs in photosynthetic organisms. To mimic the long-lived charge separations characteristic of the reaction center in photosynthesis, researchers have applied the Marcus theory to design synthetic multistep electron-transfer (ET) systems. In this Account, we describe our recent research on the rational design of ET control systems, based on models of the photosynthetic reaction center that rely on the Marcus theory of ET. The key to obtaining a long-lived charge separation is the careful choice of electron donors and acceptors that have small reorganization energies of ET. In these cases, the driving force of back ET is located in the Marcus inverted region, where the lifetime of the charge-separated state lengthens as the driving force of back ET increases. We chose porphyrins as electron donors and fullerenes as electron acceptors, both of which have small ET reorganization energies. By linking electron donor porphyrins and electron acceptor fullerenes at appropriate distances, we achieved charge-separated states with long lifetimes. We could further lengthen the lifetimes of charge-separated states by mixing a variety of components, such as a terminal electron donor, an electron mediator, and an electron acceptor, mimicking both the photosynthetic reaction center and the multistep photoinduced ET that occurs there. However, each step in multistep ET loses a fraction of the initial excitation energy during the long-distance charge separation. To overcome this drawback in multistep ET systems, we used designed new systems where we could finely control the redox potentials and the geometry of simple donor-acceptor dyads. These modifications resulted in a small ET reorganization energy and a high-lying triplet excited state. Our most successful example, 9-mesityl-10-methylacridinium ion (Acr(+)-Mes), can undergo a fast photoinduced ET from the mesityl (Mes) moiety to the singlet excited state

  14. Light-Induced Charge Separation across Bio-Inorganic Interface (United States)

    Dimitrijevic, Nada M.; de La Garza, Linda; Rajh, Tijana

    Rational design of hybrid biomolecule — nanoparticulate semiconductor conjugates enables coupling of functionality of biomolecules with the capability of semiconductors for solar energy capture, that can have potential application in energy conversion, sensing and catalysis. The particular challenge is to obtain efficient charge separation analogous to the natural photosynthesis process. The synthesis of axially anisotropic TiO2 nano-objects such as tubes, rods and bricks, as well as spherical and faceted nanoparticles has been developed in our laboratory. Depending on their size and shape, these nanostructures exhibit different domains of crystallinity, surface areas and aspect ratios. Moreover, in order to accommodate for high curvature in nanoscale regime, the surfaces of TiO2 nano-objects reconstructs resulting in changes in the coordination of surface Ti atoms from octahedral (D2d) to square pyramidal structures (C4v). The formation of these coordinatively unsaturated Ti atoms, thus depends strongly on the size and shape of nanocrystallites and affects trapping and reactivity of photogenerated charges. We have exploited these coordinatively unsaturated Ti atoms to coupe electron-donating (such as dopamine) and electron-accepting (pyrroloquinoline quinone) conductive linkers that allow wiring of biomolecules and proteins resulting in enhanced charge separation which increases the yield of ensuing chemical transformations.

  15. Spin-Charge Separation in Finite Length Metallic Carbon Nanotubes

    KAUST Repository

    Zhang, Yongyou


    Using time-dependent density functional theory, we study the optical excitations in finite length carbon nanotubes. Evidence of spin-charge separation is given in the spacetime domain. We demonstrate that the charge density wave is due to collective excitations of electron singlets, while the accompanying spin density wave is due to those of electron triplets. The Tomonaga–Luttinger liquid parameter and density–density interaction are extrapolated from the first-principles excitation energies. We show that the density–density interaction increases with the length of the nanotube. The singlet and triplet excitation energies, on the other hand, decrease for increasing length of the nanotube. Their ratio is used to establish a first-principles approach for deriving the Tomonaga–Luttinger parameter (in excellent agreement with experimental data). Time evolution analysis of the charge and spin line densities evidences that the charge and spin density waves are elementary excitations of metallic carbon nanotubes. Their dynamics show no dependence on each other.

  16. Nonlinear fluorescence probe using photoinduced charge separation (Presentation Recording) (United States)

    Mochizuki, Kentaro; Shi, Lanting; Mizukami, Shin; Yamanaka, Masahito; Tanabe, Mamoru; Gong, Wei-Tao; Palonpon, Almar F.; Kawano, Shogo; Kawata, Satoshi; Kikuchi, Kazuya; Fujita, Katsumasa


    Two-photon excitation microscopy (TPEM) provides spatial resolution beyond the optical diffraction limit using the nonlinear response of fluorescent molecules. One of the strong advantages of TPEM is that it can be performed using a laser-scanning microscope without a complicated excitation method or computational post-processing. However, TPEM has not been recognized as a super-resolution microscopy due to the use of near-infrared light as excitation source, which provides lower resolution than visible light. In our research, we aimed for the realization of nonlinear fluorescence response with visible light excitation to perform super-resolution imaging using a laser-scanning microscope. The nonlinear fluorescence response with visible light excitation is achieved by developing a probe which provides stepwise two-photon excitation through photoinduced charge separation. The probe named nitro-bisBODIPY consists of two fluorescent molecules (electron donor: D) and one electron acceptor (A), resulting to the structure of D-A-D. Excited by an incident photon, nitro-bisBODIPY generates a charge-separated pair between one of the fluorescent molecules and the acceptor. Fluorescence emission is obtained only when one more incident photon is used to excite the other fluorescent molecule of the probe in the charge-separated state. This stepwise two-photon excitation by nitro-bisBODIPY was confirmed by detection of the 2nd order nonlinear fluorescence response using a confocal microscope with 488 nm CW excitation. The physical model of the stepwise two-photon excitation was investigated by building the energy diagram of nitro-bisBODIPY. Finally, we obtained the improvement of spatial resolution in fluorescence imaging of HeLa cells using nitro-bisBODIPY.

  17. Interfacial charge separation and trapping in composite photocatalysts (United States)

    Chakarov, Dinko

    We explore the phenomena of interfacial charge separation and trapping in composite metal-semiconductor systems and the interaction (energy and charge exchange) between optically excited nanoparticles and the surrounding medium. Disc-shaped copper nanoparticles (Cu NPs) were fabricated by hole-mask colloidal lithography on bare and thin titania film covered fused silica substrates. The dynamics of Cu oxide formation around the NPs were studied in water by localized surface plasmon resonance (LSPR) spectroscopy. We found that the oxidation rate is strongly enhanced under UV irradiation when the NPs are on the surface of the titania film, in comparison to NPs deposited on an inert fused silica substrate. The reason is sought in the ability of TiO2 to create hydroxyl radicals with strong oxidative potential in water under UV irradiation and the charge transfer at the interface between the Cu NPs and the TiO2. The results demonstrate the potential of using LSPR spectroscopy to monitor the oxidation of Cu NPs in situ and in different environments. The work was financially supported by The Nordic Energy Research Council through Project N-I-S-F-D.

  18. Classification of solar cells according to mechanisms of charge separation and charge collection. (United States)

    Kirchartz, Thomas; Bisquert, Juan; Mora-Sero, Ivan; Garcia-Belmonte, Germà


    In the last decade, photovoltaics (PV) has experienced an important transformation. Traditional solar cells formed by compact semiconductor layers have been joined by new kinds of cells that are constituted by a complex mixture of organic, inorganic and solid or liquid electrolyte materials, and rely on charge separation at the nanoscale. Recently, metal organic halide perovskites have appeared in the photovoltaic landscape showing large conversion efficiencies, and they may share characteristics of the two former types. In this paper we provide a general description of the photovoltaic mechanisms of the single absorber solar cell types, combining all-inorganic, hybrid and organic cells into a single framework. The operation of the solar cell relies on a number of internal processes that exploit internal charge separation and overall charge collection minimizing recombination. There are two main effects to achieve the required efficiency, first to exploit kinetics at interfaces, favouring the required forward process, and second to take advantage of internal electrical fields caused by a built-in voltage and by the distribution of photogenerated charges. These principles represented by selective contacts, interfaces and the main energy diagram, form a solid base for the discussion of the operation of future types of solar cells. Additional effects based on ferroelectric polarization and ionic drift provide interesting prospects for investigating new PV effects mainly in the perovskite materials.

  19. The laser proton acceleration in the strong charge separation regime

    Energy Technology Data Exchange (ETDEWEB)

    Nishiuchi, M. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan)]. E-mail:; Fukumi, A. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan)]|[National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage, Chiba 263-8555 (Japan); Daido, H. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan); Li, Z. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan)]|[National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage, Chiba 263-8555 (Japan); Sagisaka, A.; Ogura, K.; Orimo, S.; Kado, M.; Hayashi, Y.; Mori, M. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan); Bulanov, S.V. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan)]|[A.M. Prokhorov General Physics Institute of Russian Academy of the Sciences, Vavilov St. 38, Moscow 119991 (Russian Federation); Esirkepov, T. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan); Nemoto, K.; Oishi, Y.; Nayuki, T.; Fujii, T. [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan); Noda, A.; Iwashita, Y.; Shirai, T. [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Nakamura, S. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemi-dai, Kizu, Kyoto 619-0215 (Japan)]|[Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)


    We report the experimental results of proton acceleration as well as the simple one-dimensional model which explains our experimental data. The proton acceleration experiment is carried out with a TW short pulse laser irradiated on a tantalum thin-foil target (3 {mu}m thickness) with an intensity of {approx}3x10{sup 18} Wcm{sup -2}. Accelerated protons exhibit a typical energy spectrum with two quasi-Maxwellian components with a high energy cut-off. We can successfully explain the higher energy part as well as the cut off energy of the proton spectrum with the simple-one-dimensional model based on the strong charge separation regime, which is the extension of the model proposed originally by [M. Passoni et al., Phys. Rev. E 69 (2004) 026411].

  20. Laser-induced charge separation in organic nanofibers

    DEFF Research Database (Denmark)

    Tavares, Luciana; Behn, Dino; Kjelstrup-Hansen, Jakob

    Organic semiconductors have unique properties that can be tailored via synthetic chemistry for specific applications, which combined with their low price and straight-forward processing over large areas make them interesting materials for future devices. Certain oligomers can self-assemble into c......Organic semiconductors have unique properties that can be tailored via synthetic chemistry for specific applications, which combined with their low price and straight-forward processing over large areas make them interesting materials for future devices. Certain oligomers can self......-assemble into crystalline nanofibers by vapor deposition onto muscovite mica substrates, and we have recently shown that such nanofibers can be transferred to different substrates by roll-printing and used as the active material in e.g. organic field-effect transistors (OFETs), organic light-emitting transistors (OLETs......), and organic phototransistors (OPTs). However, several device-related issues incl. charge-separation and local band structure remain poorly understood. In this work, we use electrostatic force microscopy (EFM) combined with optical microscopy to study the local surface charge of an individual organic nanofiber...

  1. Spin-charge separation in an Aharonov-Bohm interferometer (United States)

    Dmitriev, A. P.; Gornyi, I. V.; Kachorovskii, V. Yu.; Polyakov, D. G.


    We study manifestations of spin-charge separation (SCS) in transport through a tunnel-coupled interacting single-channel quantum ring. We focus on the high-temperature case (temperature T larger than the level spacing Δ ) and discuss both the classical (flux-independent) and interference contributions to the tunneling conductance of the ring in the presence of magnetic flux. We demonstrate that the SCS effects, which arise solely from the electron-electron interaction, lead to the appearance of a peculiar fine structure of the electron spectrum in the ring. Specifically, each level splits into a series of sublevels, with their spacing governed by the interaction strength. In the high-T limit, the envelope of the series contains of the order of T /Δ sublevels. At the same time, SCS suppresses the tunneling width of the sublevels by a factor of Δ /T . As a consequence, the classical transmission through the ring remains unchanged compared to the noninteracting case: the suppression of tunneling is compensated by the increase of the number of tunneling channels. On the other hand, the flux-dependent contribution to the conductance depends on the interaction-induced dephasing rate which is known to be parametrically increased by SCS in an infinite system. We show, however, that SCS is not effective for dephasing in the limit of weak tunneling. Moreover, generically, in the almost closed ring, the dephasing rate does not depend on the interaction strength and is determined by the tunneling coupling to the leads. In certain special symmetric cases, dephasing is further suppressed. Similarly to the spinless case, the high-T conductance shows, as a function of magnetic flux, a sequence of interaction-induced sharp negative peaks on top of the classical contribution.

  2. Separating Charges at Organic Interfaces: Effects of Disorder, Hot States, and Electric Field. (United States)

    Nayak, Pabitra K; Narasimhan, K L; Cahen, David


    Charge separation at organic-organic (O-O) interfaces is crucial to how many organic-based optoelectronic devices function. However, the mechanism of formation of spatially separated charge carriers and the role of geminate recombination remain topics of discussion and research. We review critically the contributions of the various factors, including electric fields, long-range order, and excess energy (beyond the minimum needed for photoexcitation), to the probability that photogenerated charge carriers will be separated. Understanding the processes occurring at the O/O interface and their relative importance for effective charge separation is crucial to design efficient solar cells and photodetectors. We stress that electron and hole delocalization after photoinduced charge transfer at the interface is important for efficient free carrier generation. Fewer defects at the interface and long-range order in the materials also improve overall current efficiency in solar cells. In efficient organic cells, external electric fields play only a small role for charge separation.

  3. Pharmacological separation of charge movement components in frog skeletal muscle. (United States)

    Huang, C L


    1. Charge movements to small 10 mV steps superimposed upon a wide range of closely spaced depolarizing voltage-clamp pulses were studied in frog skeletal muscles under different pharmacological conditions in hypertonic solutions.2. In control fibres, capacitance was strongly voltage-dependent, especially between potentials of -60 and -20 mV, confirming earlier work. There was a sharp increase in capacitance at around -50 mV. The dependence of non-linear charge on potential was asymmetrical and saturated at around 25 nC/muF.3. The presence of tetracaine abolished the ;hump' in the non-linear transients, which became simple monotonic decays. The dependence of capacitance upon potential was reduced. The maximum available amount of non-linear charge fell to 10 nC/muF.4. The presence of lidocaine abolished both the ;hump' as well as the monotonic part of the non-linear transients. This resulted in capacitance falling with depolarization from -85 mV.5. Comparing the steady-state properties of the non-linear charge under the different pharmacological conditions made it possible to deduce empirically the following components:(i) A lidocaine-resistant component (q(alpha)), which was responsible for the fall in observed capacitance with depolarization from the control voltage.(ii) A component resistant to tetracaine yet abolished by lidocaine (q(beta)). This possesses quasi-exponential kinetics, and a maximum charge of about 20 nC/muF.(iii) A component abolished by both lidocaine and tetracaine (q(gamma)), which possesses a maximum charge of 15 nC/muF. This has complex kinetics, and its steep dependence upon voltage resembles the potential-dependence of the development of tension in skeletal muscle.

  4. Two-Dimensional Electronic Spectroscopies for Probing Electronic Structure and Charge Transfer: Applications to Photosystem II

    Energy Technology Data Exchange (ETDEWEB)

    Ogilvie, Jennifer P. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics


    Photosystem II (PSII) is the only known natural enzyme that uses solar energy to split water, making the elucidation of its design principles critical for our fundamental understanding of photosynthesis and for our ability to mimic PSII’s remarkable properties. This report discusses progress towards addressing key open questions about the PSII RC. It describes new spectroscopic methods that were developed to answer these questions, and summarizes the outcomes of applying these methods to study the PSII RC. Using 2D electronic spectroscopy and 2D electronic Stark spectroscopy, models for the PSII RC were tested and refined. Work is ongoing to use the collected data to elucidate the charge separation mechanism in the PSII RC. Coherent dynamics were also observed in the PSII RC for the first time. Through extensive characterization and modeling we have assigned these coherences as vibronic in nature, and believe that they reflect resonances between key vibrational pigment modes and electronic energy gaps that may facilitate charge separation. Work is ongoing to definitively test the functional relevance of electronic-vibrational resonances.

  5. Impact of charge-transfer excitons in regioregular polythiophene on the charge separation at polythiophene-fullerene heterojunctions (United States)

    Polkehn, M.; Tamura, H.; Burghardt, I.


    This study addresses the mechanism of ultrafast charge separation in regioregular oligothiophene-fullerene assemblies representative of poly-3-hexylthiophene (P3HT)-[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) heterojunctions, with special emphasis on the inclusion of charge transfer excitons in the oligothiophene phase. The formation of polaronic inter-chain charge separated species in highly ordered oligothiophene has been demonstrated in recent experiments and could have a significant impact on the net charge transfer to the fullerene acceptor. The present approach combines a first-principles parametrized multi-site Hamiltonian, based on time-dependent density functional theory calculations, with accurate quantum dynamics simulations using the multi-layer multi-configuration time-dependent Hartree method. Quantum dynamical studies are carried out for up to 182 electronic states and 112 phonon modes. The present analysis follows up on our previous study of (Huix-Rotllant et al 2015 J. Phys. Chem. Lett. 6 1702) and significantly expands the scope of this analysis by including the dynamical role of charge transfer excitons. Our investigation highlights the pronounced mixing of photogenerated Frenkel excitons with charge transfer excitons in the oligothiophene domain, and the opening of new transfer channels due the creation of such charge-separated species. As a result, it turns out that the interfacial donor/acceptor charge transfer state can be largely circumvented due to the presence of charge transfer excitons. However, the latter states in turn act as a trap, such that the free carrier yield observed on ultrafast time scales is tangibly reduced. The present analysis underscores the complexity of the transfer pathways at P3HT-PCBM type junctions.

  6. On the Mechanism of the Primary Charge Separation in Bacterial Photosynthesis

    CERN Document Server

    Mak, C H; Egger, Reinhold


    We present a detailed analysis of the mechanism of the primary charge separation process in bacterial photosynthesis using real-time path integrals. Direct computer simulations as well as an approximate analytical theory have been employed to map out the dynamics of the charge separation process in many regions of the parameter space relevant to bacterial photosynthesis. Two distinct parameter regions, one characteristic of sequential transfer and the other characteristic of superexchange, have been found to yield charge separation dynamics in agreement with experiments. Nonadiabatic theory provides accurate rate estimates for low-lying and very high-lying bacteriochlorophyll state energies, but it breaks down in between these two regimes.

  7. Synthetic system mimicking the energy transfer and charge separation of natural photosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gust, D.; Moore, T.A.


    A synthetic molecular triad consisting of a porphyrin P linked to both a quinone Q and a carotenoid polyene C has been prepared as a mimic of natural photosynthesis for solar energy conversion purposes. Laser flash excitation of the porphyrin moiety yields a charge-separated state Csup(+.)-P-Qsup(-.) within 100 ps with a quantum yield of more than 0.25. This charge-separated state has a lifetime on the microsecond time scale in suitable solvents. The triad also models photosynthetic antenna function and photoprotection from singlet oxygen damge. The successful biomimicry of photosynthetic charge separation is in part the result of multistep electron transfers which rapidly separate the charges and leave the system at high potential, but with a considerable barrier to recombination.

  8. Charge separation sensitized by advanced II-VI semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, David F. [Univ.of California, Merced, CA (United States)


    This proposal focuses on how the composition and morphology of pure and alloyed II-VI semiconductor heterostructures control their spectroscopic and dynamical properties. The proposed research will use a combination of synthesis development, electron microscopy, time-resolved electronic spectroscopy and modeling calculations to study these nanostructures. The proposed research will examine the extent to which morphology, compression due to lattice mismatch and alloy effects can be used to tune the electron and hole energies and the spectroscopic properties of II-VI heterojunctions. It will also use synthesis, optical spectroscopy and HRTEM to examine the role of lattice mismatch and hence lattice strain in producing interfacial defects, and the extent to which defect formation can be prevented by controlling the composition profile through the particles and across the interfaces. Finally, we will study the magnitude of the surface roughness in core/shell nanostructures and the role of shell thickness variability on the inhomogeneity of interfacial charge transfer rates.

  9. Phase Separation of Binary Charged Particle Systems with Small Size Disparities using a Dusty Plasma. (United States)

    Killer, Carsten; Bockwoldt, Tim; Schütt, Stefan; Himpel, Michael; Melzer, André; Piel, Alexander


    The phase separation in binary mixtures of charged particles has been investigated in a dusty plasma under microgravity on parabolic flights. A method based on the use of fluorescent dust particles was developed that allows us to distinguish between particles of slightly different size. A clear trend towards phase separation even for smallest size (charge) disparities is observed. The diffusion flux is directly measured from the experiment and uphill diffusion coefficients have been determined.

  10. Formation of ion clusters in the phase separated structures of neutral-charged polymer blends (United States)

    Kwon, Ha-Kyung; Olvera de La Cruz, Monica


    Polyelectrolyte blends, consisting of at least one charged species, are promising candidate materials for fuel cell membranes, for their mechanical stability and high selectivity for proton conduction. The phase behavior of the blends is important to understand, as this can significantly affect the performance of the device. The phase behavior is controlled by χN, the Flory-Huggins parameter multiplied by the number of mers, as well as the electrostatic interactions between the charged backbone and the counterions. It has recently been shown that local ionic correlations, incorporated via liquid state (LS) theory, enhance phase separation of the blend, even in the absence of polymer interactions. In this study, we show phase diagrams of neutral-charged polymer blends including ionic correlations via LS theory. In addition to enhanced phase separation at low χN, the blends show liquid-liquid phase separation at high electrostatic interaction strengths. Above the critical strength, the charged polymer phase separates into ion-rich and ion-poor regions, resulting in the formation of ion clusters within the charged polymer phase. This can be shown by the appearance of multiple spinodal and critical points, indicating the coexistence of several charge separated phases. This work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).

  11. Exceptionally Long-Lived Charge Separated State in Zeolitic Imidazolate Framework: Implication for Photocatalytic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Pattengale, Brian [Department; Yang, Sizhuo [Department; Ludwig, John [Department; Huang, Zhuangqun [Department; Zhang, Xiaoyi [X-ray; Huang, Jier [Department


    Zeolitic Imidazolate Frameworks (ZIFs) have emerged as a novel class of porous metal-organic frameworks (MOFs) for catalysis application because of their exceptional thermal and chemical stability. Inspired by the broad absorption of ZIF-67 in UV-visible-near IR region, we explored its excited state and charge separation dynamics, properties essential for photocatalytic applications, using optical (OTA) and X-ray transient absorption (XTA) spectroscopy. OTA results show that an exceptionally long-lived excited state is formed after photoexcitation. This long-lived excited state was confirmed to be the charge separated state with ligandto-metal charge transfer character using XTA. The surprisingly long-lived charge separated state, together with its intrinsic hybrid nature, all point to its potential application in heterogeneous photocatalysis and energy conversion.

  12. Charged Polymer-Coated Separators by Atmospheric Plasma-Induced Grafting for Lithium-Ion Batteries. (United States)

    Han, Mina; Kim, Dong-Won; Kim, Yeong-Cheol


    A simple and fast method of atmospheric plasma-induced grafting was applied over a polyethylene membrane to enhance its performance as a separator for lithium-ion batteries. The process of grafting has formed a thin, durable, and uniform layer on the surface of the porous membrane. The charges of grafted polymers affected the performance of batteries in many ways besides the change of hydrophilicity. Negative charges in polymers improve the capacity retention of batteries and the uniformity of the SEI layer. On the other hand, the electrostatic attraction between different charges contributed to small increases of thermal stability and mechanical strength of separators. Polyampholyte was grafted by using the mixtures of monomers, and the composition of the grafted layer was optimized. The formation of stable uniform SEI layers and the marked improvement in capacity retention were observed in the full cell tests of the lithium battery with the polyampholyte-grafted separators when the polyampholyte has a negative net charge.

  13. Quantum - coherent dynamics in photosynthetic charge separation revealed by wavelet analysis

    NARCIS (Netherlands)

    Romero, Elisabet; Prior, Javier; Chin, Alex W.; Morgan, Sarah E.; Novoderezhkin, Vladimir I.; Plenio, Martin B.; van Grondelle, Rienk


    Experimental/theoretical evidence for sustained vibration-assisted electronic (vibronic) coherence in the Photosystem II Reaction Center (PSII RC) indicates that photosynthetic solar-energy conversion might be optimized through the interplay of electronic and vibrational quantum dynamics. This

  14. Tribo-charging properties of waste plastic granules in process of tribo-electrostatic separation. (United States)

    Li, Jia; Wu, Guiqing; Xu, Zhenming


    Plastic products can be found everywhere in people's daily life. With the consistent growth of plastic consumption, more and more plastic waste is generated. Considering the stable chemical and physics characteristics of plastic, regular waste management methods are not suitable for recycling economic strategy of each government, which has become a serious environmental problem. Recycling plastic waste is considered to be the best way to treat it, because it cannot only deduce the waste but also save the energy to produce new virgin plastic. Tribo-electrostatic separation is strongly recommended for plastic separation as it can preserve the original properties of plastic and has little additional pollution. In this study, plastic granules are generated by crushing plastic waste in waste electric and electronic equipment. The tribo-charging properties of plastic waste were studied by vibrating tribo-charging and cyclone tribo-charging. The triboelectric series obtained by vibrating was: (-)-PE-PS-PC-PVC-ABS-PP-(+), while the triboelectric series obtained by cyclone was (-)-PE-PS-PC-PVC-ABS-PP-(+). Further, the cyclone charging was more effective and stable than vibrating charging. The impact factors experiments showed that small particle size was better changed than large ones and were more suitable recycled by tribo-electrostatic separation. High relative humidity was identified as impede charging effect. The results of this study will help defining the operating parameters of subsequent separator. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Separation of intramembrane charging components in low-calcium solutions in frog skeletal muscle. (United States)

    Huang, C L


    The inactivation of charge movement components by small (-100 to -70 mV) shifts in holding potential was examined in voltage-clamped intact amphibian muscle fibers in low [Ca2+], Mg(2+)-containing solutions. The pulse protocols used both large voltage excursions and smaller potential steps that elicited prolonged (q gamma) transients. Charge species were distinguished through the pharmacological effects of tetracaine. These procedures confirmed earlier observations in cut fibers and identified the following new properties of the q gamma charge. First, q gamma, previously defined as the tetracaine-sensitive charge, is also the component primarily responsible for the voltage-dependent inactivation induced by conditions of low extracellular [Ca2+]. Second, this inactivation separates a transient that includes a "hump" component and which has kinetics and a voltage dependence distinct from the monotonic decay that remains. Third, q gamma, previously associated with delayed charge movements, can also contribute significant charge transfer at early times. These findings suggest that the parallel inhibition of calcium signals and charge movements reported in low [Ca2+] solutions arises from influences on q gamma charge (Brum et al., 1988a, b). They also reconcile reports that implicate tetracaine-sensitive (q gamma) charge in excitation-contraction coupling with evidence that early intramembrane events are also involved in this process (Pizarro et al., 1989). Finally, they are relevant to hypotheses of possible feedback or feed-forward roles of q gamma in excitation-contraction coupling.

  16. Unconventional spin-charge phase separation in a model 2D cuprate (United States)

    Panov, Yu. D.; Budrin, K. S.; Chikov, A. A.; Moskvin, A. S.


    In this Letter we address a challenging problem of a competition of charge and spin orders for high-Tc cuprates within a simplified 2D spin-pseudospin model which takes into account both conventional Heisenberg Cu2+-Cu2+ antiferromagnetic spin exchange coupling (J) and the on-site (U) and inter-site (V) charge correlations in the CuO2 planes with the on-site Hilbert space reduced to only three effective charge states (nominally Cu1+;2+;3+). We performed classical Monte-Carlo calculations for large square lattices implying the mobile doped charges and focusing on a case of a small inter-site repulsion V ≪ J. The on-site attraction (U 0) the homogeneous ground state antiferromagnetic solutions of the doped system found in a mean-field approximation are shown to be unstable with respect to a phase separation with the charge and spin subsystems behaving like immiscible quantum liquids. Puzzlingly, with lowering the temperature one can observe two sequential phase transitions: first, an antiferromagnetic ordering in the spin subsystem diluted by randomly distributed charges, then, a charge condensation in the charge droplets. The effects are illustrated by the Monte-Carlo calculations of the specific heat and longitudinal magnetic susceptibility.

  17. Long-lived photoinduced charge separation for solar cell applications in supramolecular complexes of multi-metalloporphyrins and fullerenes. (United States)

    Fukuzumi, Shunichi; Ohkubo, Kei


    Monomers, dimers, trimers, dendrimers and oligomers of metalloporphyrins form supramolecular complexes with fullerene derivatives via electrostatic interactions, π-π interactions and coordination bonds. Photoexcitation of the supramolecular complexes resulted in photoinduced electron transfer from the porphyrin moiety to the fullerene moiety to produce the charge-separated states as revealed by laser flash photolysis measurements. The rate constants of photoinduced charge separation and charge recombination in supramolecular complexes of multi-metalloporphyrins and fullerenes were also determined by laser flash photolysis measurements and the results depending on the number of porphyrins in the supramolecular complexes are discussed in terms of efficiency of photoinduced energy transfer and charge separation as well as the lifetimes of charge-separated states. The photoelectrochemical performances of solar cells composed of supramolecular complexes of monomers, dimers, dendrimers and oligomers of metalloporphyrins with fullerenes are compared in relation to the rate constants of photoinduced charge separation and charge recombination.

  18. Spin-charge separation and electron pairing instabilities in Hubbard nanoclusters. (United States)

    Kocharian, A N; Fernando, G W; Palandage, K; Davenport, J W


    Electron charge and spin pairing instabilities in various cluster geometries for attractive and repulsive electrons are studied exactly under variation of interaction strength, electron doping and temperature. The exact diagonalization, level crossing degeneracies, spin-charge separation and separate condensation of paired electron charge and opposite spins yield intriguing insights into the origin of magnetism, ferroelectricity and superconductivity seen in inhomogeneous bulk nanomaterials and various phenomena in cold fermionic atoms in optical lattices. Phase diagrams resemble a number of inhomogeneous, coherent and incoherent nanoscale phases found recently in high-T(c) cuprates, manganites and multiferroic nanomaterials probed by scanning tunneling microscopy. Separate condensation of electron charge and spin degrees at various crossover temperatures offers a new route for superconductivity, different from the BCS scenario. The calculated phase diagrams resemble a number of inhomogeneous paired phases, superconductivity, ferromagnetism and ferroelectricity found in Nb and Co nanoparticles. The phase separation and electron pairing, monitored by electron doping and magnetic field surprisingly resemble incoherent electron pairing in the family of doped high-T(c) cuprates, ruthenocuprates, iron pnictides and spontaneous ferroelectricity in multiferroic materials.

  19. Combustion of biomass - Energy recovery and dust separation with conventional and electrically charged scrubbers

    Energy Technology Data Exchange (ETDEWEB)

    Rawe, R.; Kuhrmann, H. (Univ. of Applied Sciences, Gelsenkirchen (Germany)), e-mail:


    In the last years a combined heat exchanger and spray scrubber for condensing operation of biomass boilers was investigated at the University of Applied Sciences in Gelsenkirchen. Flue gases are chilled more deeply as compared with conventional condensing boilers. This leads to the fact, that the rate of condensation is higher and more heat of vaporization can be recovered. Depending on temperatures and mode of operation, energy savings up to 17 % are realized. The high efficiency reduces overall emissions as less fuel is fired at the same heat output. In addition the wet separator minimizes emissions of particles, water-soluble flue gases and odours. With conventional scrubbers dust separation-efficiencies > 50 % can be achieved at high injection pressure of 3,5 bar. Looking at the different electrically charged scrubber types, either the particles and / or the scrubber fields are charged. Thus, up to 86 % efficiency is achieved using a dust-charging voltage of 25 kV. (orig.)

  20. Charge separation in contact systems with CdSe quantum dot layers

    Energy Technology Data Exchange (ETDEWEB)

    Zillner, Elisabeth Franziska


    Quantum dot (QD) solar cells are a fast developing area in the field of solution processed photovoltaics. Central aspects for the application of QDs in solar cells are separation and transport of charge carriers in the QD layers and the formation of charge selective contacts. Even though efficiencies of up to 7% were reached in QD solar cells, these processes are not yet fully understood. In this thesis the mechanisms of charge separation, transport and recombination in CdSe QD layers and layer systems were studied. Charge separation was measured via surface photovoltage (SPV) at CdSe QD layers with thicknesses in the range of monolayers. To determine the influence of interparticle distance of QDs and trap states on the surface of QDs on charge separation, QDs with four different surfactant layers were studied. Layers of CdSe QDs were prepared on ITO, Si, SiO{sub 2} and CdS by dip coating under inert atmosphere. The layers were characterized by Rutherford backscattering spectrometry, UV-vis spectroscopy, step profilometry and scanning electron microscopy to determine the areal density, the absorption and thickness of CdSe QD monolayers. SPV measurements show that initial charge separation from the CdSe QDs on ITO only happened from the fi rst monolayer of QDs. Electrons, photo-excited in the fi rst monolayer of CdSe QDs, were trapped on the ITO surface. The remaining free holes were trapped in surface states and/or diffused into the neighboring QD layers. The thick surfactant layer ({approx} 1.6 nm) of pristine QDs had to be reduced by washing and/or ligand exchange for separation of photo-excited charge carriers. Both, interparticle distance and trap density, influenced the processes of charge separation and recombination. SPV transients of CdSe monolayers could be described by a single QD approximation model, based on Miller-Abrahams hopping of holes between the delocalized excitonic state, traps on the surface of the QD and the filled trap on the ITO surface

  1. Self-Assembly Strategies for Integrating Light Harvesting and Charge Separation in Artificial Photosynthetic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wasielewski, Michael R. (NWU)


    In natural photosynthesis, organisms optimize solar energy conversion through organized assemblies of photofunctional chromophores and catalysts within proteins that provide specifically tailored environments for chemical reactions. As with their natural counterparts, artificial photosynthetic systems for practical solar fuels production must collect light energy, separate charge, and transport charge to catalytic sites where multielectron redox processes will occur. While encouraging progress has been made on each aspect of this complex problem, researchers have not yet developed self-ordering and self-assembling components and the tailored environments necessary to realize a fully-functional artificial system. Previously researchers have used complex, covalent molecular systems comprised of chromophores, electron donors, and electron acceptors to mimic both the light-harvesting and the charge separation functions of photosynthetic proteins. These systems allow for study of the dependencies of electron transfer rate constants on donor?acceptor distance and orientation, electronic interaction, and the free energy of the reaction. The most useful and informative systems are those in which structural constraints control both the distance and the orientation between the electron donors and acceptors. Self-assembly provides a facile means for organizing large numbers of molecules into supramolecular structures that can bridge length scales from nanometers to macroscopic dimensions. The resulting structures must provide pathways for migration of light excitation energy among antenna chromophores, and from antennas to reaction centers. They also must incorporate charge conduits, that is, molecular 'wires' that can efficiently move electrons and holes between reaction centers and catalytic sites. The central scientific challenge is to develop small, functional building blocks with a minimum number of covalent linkages, which also have the appropriate molecular

  2. Charge separation in a niobate nanosheet photocatalyst studied with photochemical labeling. (United States)

    Sabio, Erwin M; Chi, Miaofang; Browning, Nigel D; Osterloh, Frank E


    Photolabeling was employed to probe charge separation and the distribution of redox-active sites on the surface of nanosheets derived from the layered photocatalysts KCa(2)Nb(3)O(10). Electron microscopy reveals 1-50 nm particles of silver, gold, iridium oxide, and manganese dioxide particles and small atomically sized clusters of platinum and IrO(x) on the nanosheet surfaces and along the edges. The sizes, shapes, and particle densities vary with the deposition conditions, i.e., the precursor concentration and the presence of sacrificial agents. Overall, the study shows that photogenerated electrons and holes are accessible throughout the nanosheets, without evidence for spatial charge separation across the sheet.

  3. Photoinduced Charge Separation in the Carbon Nano-Onion C60@C240. (United States)

    Voityuk, Alexander A; Solà, Miquel


    The double-shell fullerene C60@C240 formed by inclusion of C60 into C240 is the smallest stable carbon nano-onion. In this article, we analyze in detail the character of the excited states of C60@C240 in terms of exciton localization and charge transfer between the inner and outer shells. The unique structure of the buckyonion leads to a large electrostatic stabilization of charge-separated (CS) states in the C60@C240. As a result, the CS states C60(+)@C240(-) lie in the same region of the electronic spectrum (2.4-2.6 eV) as strongly absorbing locally excited states and, therefore, can be effectively populated. The CS states C60(-)@C240(+) are found to be 0.5 eV higher in energy than the CS states C60(+)@C240(-). Unlike the situation observed in donor-acceptor systems, the energies of the CS states in C60@C240 do not practically depend on the environment polarity. This leads to exceptionally small reorganization energies for electron transfer between the shells. Electronic couplings for photoinduced charge-separation and charge-recombination processes are calculated. The absolute rate of the formation of the CS state C60(+)@C240(-) is estimated at ∼4 ps(-1). The electronic features found in C60@C240 are likely to be shared by other carbon nano-onions.

  4. Charge separation energetics at organic heterojunctions: on the role of structural and electrostatic disorder. (United States)

    Castet, Frédéric; D'Avino, Gabriele; Muccioli, Luca; Cornil, Jérôme; Beljonne, David


    Improving the performance of organic photovoltaic cells requires the individuation of the specific factors limiting their efficiency, by rationalizing the relationship between the chemical nature of the materials, their morphology, and the electronic processes taking place at their interface. In this contribution, we present recent theoretical advances regarding the determination of the energetics and dynamics of charge carriers at organic-organic interfaces, highlighting the role of structural and electrostatic disorder in the separation of electron-hole pairs. The influence of interfacial electrostatic interactions on charge carrier energetics is first illustrated in model aggregates. Then, we review some of our recent theoretical studies in which we combined molecular dynamics, quantum-chemical and classical micro-electrostatic methods to evaluate the energy landscape explored by the mobile charges in the vicinity of donor-acceptor interfaces with realistic morphologies. Finally, we describe the theoretical challenges that still need to be overcome in order to gain a complete overview of the charge separation processes at the molecular level.

  5. Kinetic separation of charge movement components in intact frog skeletal muscle. (United States)

    Huang, C L


    1. Procedures for a complete charge movement separation employed a combination of its steady-state inactivation and activation properties in intact frog skeletal muscle fibres in gluconate-containing solutions. 2. Holding potential shifts from -70 to -50 mV reduced the total charge available between -90 and -20 mV from 16.76 +/- 1.70 nC microF-1 (mean +/- S.E.M.; n = 4 fibres) to 9.25 +/- 1.43 nC microF-1 without significant loss of tetracaine-resistant charge (q beta). 3. The steady-state and kinetic properties of tetracaine-sensitive charge (q gamma) persisted through holding potential changes from -90 to -70 mV in the presence of gluconate and generally resembled activation properties established hitherto in sulphate-containing solutions. 4. Further holding potential displacement to -50 mV abolished q gamma charge movements and depressed the charge-voltage curve. 5. Test voltage steps applied from a -70 mV prepulse level gave rapid monotonic q beta decays and similarly depressed activation functions in 2 mM tetracaine unchanged by holding potential shifts between -70 and -50 mV. 6. The isolated 'on' q gamma charge movements, I(t), always included early transients that preceded any prolonged charging phases and which increased with depolarization. They decayed to stable baselines in the absence of prolonged time-dependent or inward-current phases and yielded integrals, Q(t), that monotonically increased with test voltage. 7. 'Off' steps always elicited rapid monotonic q gamma decays that fully returned the 'on' charge. 8. 'On' and 'off' q gamma currents, I(t), following voltage steps from fixed conditioning to varying test levels mapped onto topologically distinct higher-order phase-plane trajectories, I(Q), that steeply varied with test voltage. 9. In contrast, voltage steps to fixed test potentials of either -70 or -20 mV elicited identical q gamma phase-plane trajectories independent of prepulse history. 10. The q gamma current thus reflects an independent

  6. Insights into collaborative separation process of photogenerated charges and superior performance of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiangyang, E-mail:; Wang, Shun; Zheng, Haiwu; Gu, Yuzong [Institute of Microsystems Physics and School of Physics and Electronics, Henan University, Kaifeng 475004 (China)


    ZnO nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} (ZnO/CBS) and ZnO nanowires/CBS-graphene nanoplates (ZnO/CBS-GNs), as well as two types of solar cells were prepared. The photovoltaic responses of CBS-GNs and ZnO/CBS-GNs can be improved with incorporation of GNs. The transient surface photovoltage (TPV) can provide detailed information on the separation and transport of photogenerated carriers. The multichannel separation process from the TPVs indicates that the macro-photoelectric signals can be attributed to the photogenerated charges separated at the interface of CBS/GNs, rather than CBS/ZnO. The multi-interfacial recombination is the major carrier loss, and the hole selective p-V{sub 2}O{sub 5} can efficiently accelerate the charge extraction to the external circuit. The ZnO/CBS-GNs cell exhibits the superior performance, and the highest efficiency is 10.9%. With the adequate interfaces of CBS/GNs, GNs conductive network, energy level matching, etc., the excitons can easily diffuse to the interface of CBS/GNs, and the separated electrons and holes can be collected quickly, inducing the high photoelectric properties. Here, a facile strategy for solid state solar cells with superior performance presents a potential application.

  7. Electrostatic interactions and aqueous two-phase separation modes of aqueous mixed oppositely charged surfactants system. (United States)

    Hao, Li-Sheng; Gui, Yuan-Xiang; Chen, Yan-Mei; He, Shao-Qing; Nan, Yan-Qing; You, Yi-Lan


    Electrostatic interactions play an important role in setting the aqueous two-phase separation behaviors of mixtures of oppositely charged surfactants. The aqueous mixture of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfonate (AS) is actually a five-component system, comprised of CTAB, AS, complex salt (cetyltrimethylammonium dodecylsulfonate, abbreviated as CTA(+)AS(-)), NaBr, and water. In the three-dimensional pyramid phase diagram, the aqueous two-phase region with excess AS or with excess CTAB extends successively from the region very near to the NaBr-H2O line through the CTAB-AS-H2O conventional mixing plane to the CTA(+)AS(-)-AS-H2O side plane or to the CTA(+)AS(-)-CTAB-H2O side plane, respectively. Large or small molar ratios between the counterions and their corresponding surfactant ions for oppositely charged surfactants located in the NaBr side or the CTA(+)AS(-) side of the pyramid imply strong or weak electrostatic screening. Electrostatic screening of counterions alters the electrostatic attractions between the oppositely charged head groups or the electrostatic repulsions between the like-charged head groups in excess, and the electrostatic free energy of aggregation thus affects the aqueous two-phase separation modes. Composition analysis, rheological property investigation, and TEM images suggest that there are two kinds of aqueous two-phase systems (ATPSs). On the basis of these experimental results and Kaler's cell model, two kinds of phase separation modes were proposed. Experimental results also indicate that all of the top phases are surfactant-rich, and all of the bottom phases are surfactant-poor; the density difference between the top phase and the bottom phase in one ATPS is very small; the interfacial tension (σ) of the ATPS is ultralow.


    Energy Technology Data Exchange (ETDEWEB)

    Cochran, T.M.; Gaylor, T.N.; de la Garza, L.; Rajh, T.


    Dye-sensitized solar cells are potentially one of the best solutions to solar energy conversion because of the low cost of required materials and production processes. Titanium dioxide (TiO2) nanoparticulate fi lms are the basis for one of these types of cells, providing large surface area for dye-sensitizer adsorption. Because TiO2 nanoparticulate fi lms develop defects caused by oxygen defi ciency, deep reactive electron traps are formed. With the addition of an enediol ligand, these electron traps are deliberately removed, enhancing the conduction of electrons within the fi lm. In this project, TiO2 nanoparticulate fi lms made by a layer-by-layer dip coating method were modifi ed with 3,4-dihydroxyphenylacetic acid (DOPAC). DOPAC binds to the titanium atoms on the surface of the nanoparticles, restoring their octahedral geometry. This restructuring of the surface shifts the spectral properties of the TiO2 to the visible spectrum and improves the separation of charges which is observed using photoelectrochemistry. Furthermore, DOPAC enables the electronic attachment of other molecules to the surface of TiO2 fi lms, such as the conductive polymer polyaniline base. This conductive polymer provides an extended separation of charges which increases photocurrent production by forming a triad with the TiO2 semiconductor through the 3,4-dihydroxyphenylacetic acid linker. The photocurrent increases due to the donor properties of the conductive polymer thereby decreasing charge pair recombination.

  9. Spatially separated charge densities of electrons and holes in organic-inorganic halide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dan; Liang, Chunjun, E-mail:, E-mail:; Zhang, Huimin; You, Fangtian; He, Zhiqun, E-mail:, E-mail: [Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Science, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Chunxiu [Information Recording Materials Lab, Beijing Institute of Graphic Communication, Beijing 102600 (China)


    Solution-processable methylammonium lead trihalide perovskites exhibit remarkable high-absorption and low-loss properties for solar energy conversion. Calculation from density functional theory indicates the presence of non-equivalent halogen atoms in the unit cell because of the specific orientation of the organic cation. Considering the 〈100〉 orientation as an example, I{sub 1}, one of the halogen atoms, differs from the other iodine atoms (I{sub 2} and I{sub 3}) in terms of its interaction with the organic cation. The valance-band-maximum (VBM) and conduction-band-minimum (CBM) states are derived mainly from 5p orbital of I{sub 1} atom and 6p orbital of Pb atom, respectively. The spatially separated charge densities of the electrons and holes justify the low recombination rate of the pure iodide perovskite. Chlorine substitution further strengthens the unique position of the I{sub 1} atom, leading to more localized charge density around the I{sub 1} atom and less charge density around the other atoms at the VBM state. The less overlap of charge densities between the VBM and CBM states explains the relatively lower carrier recombination rate of the iodine-chlorine mixed perovskite. Chlorine substitution significantly reduces the effective mass at a direction perpendicular to the Pb-Cl bond and organic axis, enhancing the carrier transport property of the mixed perovskite in this direction.

  10. Symmetry-protected topological phases of one-dimensional interacting fermions with spin-charge separation (United States)

    Montorsi, Arianna; Dolcini, Fabrizio; Iotti, Rita C.; Rossi, Fausto


    The low energy behavior of a huge variety of one-dimensional interacting spinful fermionic systems exhibits spin-charge separation, described in the continuum limit by two sine-Gordon models decoupled in the charge and spin channels. Interaction is known to induce, besides the gapless Luttinger liquid phase, eight possible gapped phases, among which are the Mott, Haldane, charge-/spin-density, and bond-ordered wave insulators, and the Luther Emery liquid. Here we prove that some of these physically distinct phases have nontrivial topological properties, notably the presence of degenerate protected edge modes with fractionalized charge/spin. Moreover, we show that the eight gapped phases are in one-to-one correspondence with the symmetry-protected topological (SPT) phases classified by group cohomology theory in the presence of particle-hole symmetry P. The latter result is also exploited to characterize SPT phases by measurable nonlocal order parameters which follow the system evolution to the quantum phase transition. The implications on the appearance of exotic orders in the class of microscopic Hubbard Hamiltonians, possibly without P symmetry at higher energies, are discussed.

  11. Photoinduced charge separation in a colloidal system of exfoliated layered semiconductor controlled by coexisting aluminosilicate clay. (United States)

    Nakato, Teruyuki; Yamada, Yoshimi; Miyamoto, Nobuyoshi


    We investigated photoinduced charge separation occurring in a multicomponent colloidal system composed of oxide nanosheets of photocatalytically active niobate and photochemically inert clay and electron accepting methylviologen dications (MV2+). The inorganic nanosheets were obtained by exfoliation of layered hexaniobate and hectorite clay. The niobate and clay nanosheets were spatially separated in the colloidally dispersed state, and the MV2+ molecules were selectively adsorbed on the clay platelets. UV irradiation of the colloids led to electron transfer from the niobate nanosheets to the MV2+ molecules adsorbed on clay. The photoinduced electron transfer produced methylviologen radical cations (MV*+), which was characterized by high yield and long lifetime. The yield and stability of the MV*+ species were found to depend strongly on the clay content of the colloid: from a few mol % to approximately 70 mol % of the yield and several tens of minutes to more than 40 h of the lifetime. The contents of the niobate nanosheets and MV2+ molecules and the aging of the colloid also affected the photoinduced charge separation. In the absence of MV2+ molecules in the colloid, UV irradiation induced electron accumulation in the niobate nanosheets. The stability of the electron-accumulated state also depended on the clay content. The variation in the photochemical behavior is discussed in relation to the viscosity of the colloid.

  12. Event-shape-engineering study of charge separation in heavy-ion collisions (United States)

    Wen, Fufang; Bryon, Jacob; Wen, Liwen; Wang, Gang


    Recent measurements of charge-dependent azimuthal correlations in high-energy heavy-ion collisions have indicated charge-separation signals perpendicular to the reaction plane, and have been related to the chiral magnetic effect (CME). However, the correlation signal is contaminated with the background caused by the collective motion (flow) of the collision system, and an effective approach is needed to remove the flow background from the correlation. We present a method study with simplified Monte Carlo simulations and a multi-phase transport model, and develop a scheme to reveal the true CME signal via event-shape engineering with the flow vector of the particles of interest. Supported by a grant (DE-FG02-88ER40424) from U.S. Department of Energy, Office of Nuclear Physics

  13. Excited-state dynamics of hybrid multichromophoric systems: toward an excitation wavelength control of the charge separation pathways. (United States)

    Banerji, Natalie; Duvanel, Guillaume; Perez-Velasco, Alejandro; Maity, Santanu; Sakai, Naomi; Matile, Stefan; Vauthey, Eric


    The photophysical properties of two hybrid multichromophoric systems consisting of an oligophenylethynyl (OPE) scaffold decorated by 10 red or blue naphthalene diimides (NDIs) have been investigated using femtosecond spectroscopy. Ultrafast charge separation was observed with both red and blue systems. However, the nature of the charge-separated state and its lifetime were found to differ substantially. For the red system, electron transfer occurs from the OPE scaffold to an NDI unit, independently of whether the OPE or an NDI is initially excited. However, charge separation upon OPE excitation is about 10 times faster, and takes place with a 100 fs time constant. The average lifetime of the ensuing charge-separated state amounts to about 650 ps. Charge separation in the blue system depends on which of the OPE scaffold or an NDI is excited. In the first case, an electron is transferred from the OPE to an NDI and the hole subsequently shifts to another NDI unit, whereas in the second case symmetry-breaking charge separation between two NDI units occurs. Although the charges are located on two NDIs in both cases, different recombination dynamics are observed. This is explained by the location of the ionic NDI moieties that depends on the charge separation pathway, hence on the excitation wavelength. The very different dynamics observed with red and blue systems can be accounted for by the oxidation potentials of the respective NDIs that are higher and lower than that of the OPE scaffold. Because of this, the relative energies of the two charge-separated states (hole on the OPE or an NDI) are inverted.

  14. Detection of spin entanglement via spin-charge separation in crossed Tomonaga-Luttinger liquids. (United States)

    Schroer, Alexander; Braunecker, Bernd; Levy Yeyati, Alfredo; Recher, Patrik


    We investigate tunneling between two spinful Tomonaga-Luttinger liquids (TLLs) realized, e.g., as two crossed nanowires or quantum Hall edge states. When injecting into each TLL one electron of opposite spin, the dc current measured after the crossing differs for singlet, triplet, or product states. This is a striking new non-Fermi liquid feature because the (mean) current in a noninteracting beam splitter is insensitive to spin entanglement. It can be understood in terms of collective excitations subject to spin-charge separation. This behavior may offer an easier alternative to traditional entanglement detection schemes based on current noise, which we show to be suppressed by the interactions.

  15. Self-assembly of semiconductor organogelator nanowires for photoinduced charge separation. (United States)

    Wicklein, André; Ghosh, Suhrit; Sommer, Michael; Würthner, Frank; Thelakkat, Mukundan


    We investigated an innovative concept of general validity based on an organogel/polymer system to generate donor-acceptor nanostructures suitable for charge generation and charge transport. An electron conducting (acceptor) perylene bisimide organogelator forms nanowires in suitable solvents during gelation process. This phenomenon was utilized for its self-assembly in an amorphous hole conducting (donor) polymer matrix to realize an interpenetrating donor-acceptor interface with inherent morphological stability. The self-assembly and interface generation were carried out either stepwise or in a single-step. Morphology of the donor-acceptor network in thin films obtained via both routes were studied by a combination of scanning electron microscopy and atomic force microscopy. Additionally, photoinduced charge separation and charge transport in these systems were tested in organic solar cells. Fabrication steps of multilayer organogel/polymer photovoltaic devices were optimized with respect to morphology and surface roughness by introducing additional smoothening layers and charge injection/blocking layers. An inverted cell geometry was used here in which electrons are collected at the bottom electrode and holes at the top electrode. The simultaneous preparation of the interface exhibits almost 3-fold improvement in device characteristics compared to the successive method. The device characteristics under AM1.5 spectral conditions and 100 mW/cm(2) for the simultaneous preparation route are short circuit current J(sc) = 0.28 mA cm(-2), open circuit voltage V(OC) = 390 mV, fill factor FF = 38%, and a power conversion efficiency eta = 0.041%.

  16. Direct measurement of photoinduced charge separation distances in donor-acceptor systems for artificial photosynthesis using OOP-ESEEM. (United States)

    Carmieli, Raanan; Mi, Qixi; Ricks, Annie Butler; Giacobbe, Emilie M; Mickley, Sarah M; Wasielewski, Michael R


    The distance over which two photogenerated charges are separated in electron donor-acceptor systems for artificial photosynthesis depends on the structure of the system, while the lifetime of the charge separation and, ultimately, its ability to carry out useful redox chemistry depend on the electronic coupling between the oxidized donor and reduced acceptor. The radical ions produced by charge separation are frequently delocalized over the pi systems of the final oxidized donor and reduced acceptor, so that there is often significant uncertainty as to the average distance between the separated charges, especially in low dielectric constant media, where the Coulomb attraction of the ions may be significant and the charge distribution of the ions may be distorted, so that the average distance between them may be shorter than that implied by their chemical structures. The charge separation distances between photogenerated radical ions in three donor-acceptor molecules having different donor-acceptor distances were measured directly from their dipolar spin-spin interactions using out-of-phase electron spin echo envelope modulation (OOP-ESEEM). The measured distances in toluene at 85 K compare favorably to the calculated distances between the centroids of the spin distributions of the radical ions within the radical ion pairs. These results show that despite the intrinsically nonpolar nature of medium, the spin (and charge) distributions of the RPs are not significantly distorted by Coulomb attraction over these long distances. This study shows that OOP-ESEEM is well-suited for probing the detailed structural features of charge-separated intermediates that are essential to understanding how to design molecular structures that prolong and control charge separation for artificial photosynthesis.

  17. Conjugated ionomers for photovoltaic applications: electric field driven charge separation in organic photovoltaics. Final Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Lonergan, Mark [Univ. of Oregon, Eugene, OR (United States)


    Final technical report for Conjugated ionomers for photovoltaic applications, electric field driven charge separation in organic photovoltaics. The central goal of the work we completed was been to understand the photochemical and photovoltaic properties of ionically functionalized conjugated polymers (conjugated ionomers or polyelectrolytes) and energy conversion systems based on them. We primarily studied two classes of conjugated polymer interfaces that we developed based either upon undoped conjugated polymers with an asymmetry in ionic composition (the ionic junction) or doped conjugated polymers with an asymmetry in doping type (the p-n junction). The materials used for these studies have primarily been the polyacetylene ionomers. We completed a detailed study of p-n junctions with systematically varying dopant density, photochemical creation of doped junctions, and experimental and theoretical work on charge transport and injection in polyacetylene ionomers. We have also completed related work on the use of conjugated ionomers as interlayers that improve the efficiency or organic photovoltaic systems and studied several important aspects of the chemistry of ionically functionalized semiconductors, including mechanisms of so-called "anion-doping", the formation of charge transfer complexes with oxygen, and the synthesis of new polyfluorene polyelectrolytes. We also worked worked with the Haley group at the University of Oregon on new indenofluorene-based organic acceptors.

  18. Superconductivity, charge-density waves, antiferromagnetism, and phase separation in the Hubbard-Holstein model (United States)

    Karakuzu, Seher; Tocchio, Luca F.; Sorella, Sandro; Becca, Federico


    By using variational wave functions and quantum Monte Carlo techniques, we investigate the interplay between electron-electron and electron-phonon interactions in the two-dimensional Hubbard-Holstein model. Here, the ground-state phase diagram is triggered by several energy scales, i.e., the electron hopping t , the on-site electron-electron interaction U , the phonon energy ω0, and the electron-phonon coupling g . At half filling, the ground state is an antiferromagnetic insulator for U ≳2 g2/ω0 , while it is a charge-density-wave (or bipolaronic) insulator for U ≲2 g2/ω0 . In addition to these phases, we find a superconducting phase that intrudes between them. For ω0/t =1 , superconductivity emerges when both U /t and 2 g2/t ω0 are small; then, by increasing the value of the phonon energy ω0, it extends along the transition line between antiferromagnetic and charge-density-wave insulators. Away from half filling, phase separation occurs when doping the charge-density-wave insulator, while a uniform (superconducting) ground state is found when doping the superconducting phase. In the analysis of finite-size effects, it is extremely important to average over twisted boundary conditions, especially in the weak-coupling limit and in the doped case.

  19. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Energy Technology Data Exchange (ETDEWEB)

    Ohmura, Satoshi, E-mail: [Research Center for Condensed Matter Physics, Department of Civil Engineering and Urban Design, Hiroshima Institute of Technology, Hiroshima 731-5193 (Japan); Tsuruta, Kenji [Department of Electrical and Electronic Engineering, Okayama University, Okayama 700-8530 (Japan); Shimojo, Fuyuki [Department of Physics, Kumamoto University, Kumamoto 860-8555 Japan (Japan); Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Computer Science, Department of Physics & Astronomy, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, CA90089-024 (United States)


    Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC)-triethylene glycol (TEG)–C{sub 60} molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D{sup +} and A{sup -}) in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  20. Charge separation and carrier dynamics in donor-acceptor heterojunction photovoltaic systems

    Directory of Open Access Journals (Sweden)

    Joël Teuscher


    Full Text Available Electron transfer and subsequent charge separation across donor-acceptor heterojunctions remain the most important areas of study in the field of third-generation photovoltaics. In this context, it is particularly important to unravel the dynamics of individual ultrafast processes (such as photoinduced electron transfer, carrier trapping and association, and energy transfer and relaxation, which prevail in materials and at their interfaces. In the frame of the National Center of Competence in Research “Molecular Ultrafast Science and Technology,” a research instrument of the Swiss National Science Foundation, several groups active in the field of ultrafast science in Switzerland have applied a number of complementary experimental techniques and computational simulation tools to scrutinize these critical photophysical phenomena. Structural, electronic, and transport properties of the materials and the detailed mechanisms of photoinduced charge separation in dye-sensitized solar cells, conjugated polymer- and small molecule-based organic photovoltaics, and high-efficiency lead halide perovskite solar energy converters have been scrutinized. Results yielded more than thirty research articles, an overview of which is provided here.

  1. Comparison of the Impact of Zinc Vacancies on Charge Separation and Charge Transfer at ZnO/Sexithienyl and ZnO/Fullerene Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hong [School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta GA 30332-0400 USA; Bredas, Jean-Luc [Solar and Photovoltaics Engineering Research Center, Physical Science and Engineering Division, King Abdullah University of Science and Technology-KAUST, Thuwal 23955-6900 Kingdom of Saudi Arabia


    The impact of surface zinc vacancies on charge transfer and charge separation at donor/ZnO and acceptor/ZnO interfaces is identified via density functional theory calculations. The results show their effect to be related to the stronger internal electric field present near these vacancies. Thus, such surface defects can have a significant negative impact on the performance of hybrid solar cells using ZnO as electron acceptors.

  2. Effect of bridge on energy transfer and photoinduced charge separation in perylene-diimide-naphthalene-bisimide-hexathiophene based donor-bridge-acceptor triads

    Directory of Open Access Journals (Sweden)

    Tilley T.D.


    Full Text Available Femtosecond transient absorption spectroscopy is performed to assess bridge effects on energy transfer and charge separation in molecular junctions. A short, conjugated bridge can facilitate charge separation from both donor and acceptor, whereas in longer bridges charge separation only occurs from the excited donor.

  3. Macroscopic Polarization Enhancement Promoting Photo- and Piezoelectric-Induced Charge Separation and Molecular Oxygen Activation. (United States)

    Huang, Hongwei; Tu, Shuchen; Zeng, Chao; Zhang, Tierui; Reshak, Ali H; Zhang, Yihe


    Efficient photo- and piezoelectric-induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO 3 . The replacement of V 5+ ions for I 5+ in IO 3 polyhedra gives rise to strengthened macroscopic polarization of BiOIO 3 , which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo- and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals ( . O 2 - ) and hydroxyl radicals ( . OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi-responsive catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Scattering of charged particles on two spatially separated time-periodic optical fields (United States)

    Szabó, Lóránt Zs.; Benedict, Mihály G.; Földi, Péter


    We consider a monoenergetic beam of moving charged particles interacting with two separated oscillating electric fields. Time-periodic linear potential is assumed to model the light-particle interaction using a nonrelativistic, quantum mechanical description based on Gordon-Volkov states. Applying Floquet theory, we calculate transmission probabilities as a function of the laser field parameters. The transmission resonances in this Ramsey-like setup are interpreted as if they originated from a corresponding static double-potential barrier with heights equal to the ponderomotive potential resulting from the oscillating field. Due to the opening of new "Floquet channels," the resonances are repeated at input energies when the corresponding frequency is shifted by an integer multiple of the exciting frequency. These narrow resonances can be used as precise energy filters. The fine structure of the transmission spectra is determined by the phase difference between the two oscillating light fields, allowing for the optical control of the transmission.

  5. Controlling light absorption in charge-separating core/shell semiconductor nanocrystals. (United States)

    Mahadevu, Rekha; Yelameli, Aniruddha R; Panigrahy, Bharati; Pandey, Anshu


    Semiconductor nanocrystals of different formulations have been extensively studied for use in thin-film photovoltaics. Materials used in such devices need to satisfy the stringent requirement of having large absorption cross sections. Hence, type-II semiconductor nanocrystals that are generally considered to be poor light absorbers have largely been ignored. In this article, we show that type-II semiconductor nanocrystals can be tailored to match the light-absorption abilities of other types of nanostructures as well as bulk semiconductors. We synthesize type-II ZnTe/CdS core/shell nanocrystals. This material is found to exhibit a tunable band gap as well as absorption cross sections that are comparable to CdTe. This result has significant implications for thin-film photovoltaics, where the use of type-II nanocrystals instead of pure semiconductors can improve charge separation while also providing a much needed handle to regulate device composition.

  6. A Facile Approach Towards Multicomponent Supramolecular Structures: Selective Self-Assembly via Charge Separation (United States)

    Zheng, Yao-Rong; Zhao, Zhigang; Wang, Ming; Ghosh, Koushik; Pollock, J. Bryant; Cook, Timothy R.; Stang, Peter J.


    A novel approach towards the construction of multicomponent two-dimensional (2-D) and three-dimensional (3-D) metallosupramolecules is reported. Simply by mixing carboxylate and pyridyl ligands with cis-Pt(PEt3)2(OTf)2 in a proper ratio, coordination-driven self-assembly occurs, allowing for selective generation of discrete multicomponent structures via charge separation on the metal centers. Using this method, a variety of 2-D rectangles and 3-D prisms were prepared under mild conditions. Moreover, multicomponent self-assembly can also be achieved by supramolecule-to-supramolecule transformations. The products were characterized by 31P and 1H multinuclear NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and pulsed-field-gradient spin echo (PGSE) NMR techniques together with computational simulations. PMID:21053935

  7. Long-lived charge-separated states in ligand-stabilized silver clusters

    KAUST Repository

    Pelton, Matthew


    Recently developed synthesis methods allow for the production of atomically monodisperse clusters of silver atoms stabilized in solution by aromatic thiol ligands, which exhibit intense absorption peaks throughout the visible and near-IR spectral regions. Here we investigated the time-dependent optical properties of these clusters. We observed two kinetic processes following ultrafast laser excitation of any of the absorption peaks: a rapid decay, with a time constant of 1 ps or less, and a slow decay, with a time constant that can be longer than 300 ns. Both time constants decrease as the polarity of the solvent increases, indicating that the two processes correspond to the formation and recombination, respectively, of a charge-separated state. The long lifetime of this state and the broad optical absorption spectrum mean that the ligand-stabilized silver clusters are promising materials for solar energy harvesting. © 2012 American Chemical Society.

  8. Separation analysis of macrolide antibiotics with good performance on a positively charged C18HCE column. (United States)

    Wei, Jie; Shen, Aijin; Yan, Jingyu; Jin, Gaowa; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao


    The separation of basic macrolide antibiotics suffers from peak tailing and poor efficiency on traditional silica-based reversed-phase liquid chromatography columns. In this work, a C18HCE column with positively charged surface was applied to the separation of macrolides. Compared with an Acquity BEH C18 column, the C18HCE column exhibited superior performance in the aspect of peak shape and separation efficiency. The screening of mobile phase additives including formic acid, acetic acid and ammonium formate indicated that formic acid was preferable for providing symmetrical peak shapes. Moreover, the influence of formic acid content was investigated. Analysis speed and mass spectrometry compatibility were also taken into account when optimizing the separation conditions for liquid chromatography coupled with tandem mass spectrometry. The developed method was successfully utilized for the determination of macrolide residues in a honey sample. Azithromycin was chosen as the internal standard for the quantitation of spiramycin and tilmicosin, while roxithromycin was used for erythromycin, tylosin, clarithromycin, josamycin and acetylisovaleryltylosin. Good correlation coefficients (r(2) > 0.9938) for all macrolides were obtained. The intra-day and inter-day recoveries were 73.7-134.7% and 80.7-119.7% with relative standard deviations of 2.5-8.0% and 3.9-16.1%, respectively. Outstanding sensitivity with limits of quantitation (S/N ≥ 10) of 0.02-1 μg/kg and limits of detection (S/N ≥ 3) of 0.01-0.5 μg/kg were achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Optimizing multi-step B-side charge separation in photosynthetic reaction centers from Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Faries, Kaitlyn M. [Washington Univ., St. Louis, MO (United States); Kressel, Lucas L. [Argonne National Lab. (ANL), Argonne, IL (United States); Dylla, Nicholas P. [Argonne National Lab. (ANL), Argonne, IL (United States); Wander, Marc J. [Argonne National Lab. (ANL), Argonne, IL (United States); Hanson, Deborah K. [Argonne National Lab. (ANL), Argonne, IL (United States); Holten, Dewey [Washington Univ., St. Louis, MO (United States); Laible, Philip D. [Argonne National Lab. (ANL), Argonne, IL (United States); Kirmaier, Christine [Washington Univ., St. Louis, MO (United States)


    Using high-throughput methods for mutagenesis, protein isolation and charge-separation functionality, we have assayed 40 Rhodobacter capsulatus reaction center (RC) mutants for their P+ QB- yield (P is a dimer of bacteriochlorophylls and Q is a ubiquinone) as produced using the normally inactive B-side cofactors BB and HB (where B is a bacteriochlorophyll and H is a bacteriopheophytin). Two sets of mutants explore all possible residues at M131 (M polypeptide, native residue Val near HB) in tandem with either a fixed His or a fixed Asn at L181 (L polypeptide, native residue Phe near BB). A third set of mutants explores all possible residues at L181 with a fixed Glu at M131 that can form a hydrogen bond to HB. For each set of mutants, the results of a rapid millisecond screening assay that probes the yield of P+ QB- are compared among that set and to the other mutants reported here or previously. For a subset of eight mutants, the rate constants and yields of the individual B-side electron transfer processes are determined via transient absorption measurements spanning 100 fs to 50 μs. The resulting ranking of mutants for their yield of P+ QB- from ultrafast experiments is in good agreement with that obtained from the millisecond screening assay, further validating the efficient, high-throughput screen for B-side transmembrane charge separation. Results from mutants that individually show progress toward optimization of P+ HB- → P+ QB- electron transfer or initial P* → P+ HB- conversion highlight unmet challenges of optimizing both processes simultaneously.

  10. Femtosecond charge separation in organized assemblies: free-radical reactions with pyridine nucleotides in micelles. (United States)

    Gauduel, Y; Berrod, S; Migus, A; Yamada, N; Antonetti, A


    Femtosecond laser UV pulse-induced charge separation and electron transfer across a polar interface have been investigated in anionic aqueous micells (sodium lauryl sulfate) containing an aromatic hydrocarbon (phenothiazine). The early events of the photoejection of the electron from the micellized chromophore and subsequent reaction of electron with the aqueous perimicellar phase have been studied by ultrafast infrared and visible absorption spectroscopy. The charge separation (chromophore +...e-) inside the micelle occurs in less than 10(-13) s (100 fs). The subsequent thermalization and localization of the photoelectron in the aqueous phase are reached in 250 fs. This results in the appearance of an infrared band assigned to a nonrelaxed solvated electron (presolvated state). This transient species relaxes toward the fully solvated state of the electron in 270 fs. In anionic aqueous micelles containing pyridine dinucleotides at high concentration (0.025-0.103 M), a single electron transfer can be initiated by femtosecond photoionization of phenothiazine. The one-electron reduction of the oxidized pyridine dinucleotide leads to the formation of a free pyridinyl radical. The bimolecular rate constant of this electron transfer depends on both the pH of the micellar system and the concentration of oxidized acceptor. The free-radical reaction is analyzed in terms of the time dependence of a diffusion-controlled process. In the first 2 ps following the femtosecond photoionization of PTH inside the micelle, an early formation of a free pyridinyl radical is observed. This suggests that an ultrafast free-radical reaction with an oxidized form of pyridine nucleotide can be triggered by a single electron transfer in less than 5 X 10(11) s-1.

  11. Improved Charge Separation in WO3/CuWO4 Composite Photoanodes for Photoelectrochemical Water Oxidation (United States)

    Wang, Danping; Bassi, Prince Saurabh; Qi, Huan; Zhao, Xin; Gurudayal; Wong, Lydia Helena; Xu, Rong; Sritharan, Thirumany; Chen, Zhong


    Porous tungsten oxide/copper tungstate (WO3/CuWO4) composite thin films were fabricated via a facile in situ conversion method, with a polymer templating strategy. Copper nitrate (Cu(NO3)2) solution with the copolymer surfactant Pluronic®F-127 (Sigma-Aldrich, St. Louis, MO, USA, generic name, poloxamer 407) was loaded onto WO3 substrates by programmed dip coating, followed by heat treatment in air at 550 °C. The Cu2+ reacted with the WO3 substrate to form the CuWO4 compound. The composite WO3/CuWO4 thin films demonstrated improved photoelectrochemical (PEC) performance over WO3 and CuWO4 single phase photoanodes. The factors of light absorption and charge separation efficiency of the composite and two single phase films were investigated to understand the reasons for the PEC enhancement of WO3/CuWO4 composite thin films. The photocurrent was generated from water splitting as confirmed by hydrogen and oxygen gas evolution, and Faradic efficiency was calculated based on the amount of H2 produced. This work provides a low-cost and controllable method to prepare WO3-metal tungstate composite thin films, and also helps to deepen the understanding of charge transfer in WO3/CuWO4 heterojunction. PMID:28773473

  12. Improved Charge Separation in WO3/CuWO4 Composite Photoanodes for Photoelectrochemical Water Oxidation

    Directory of Open Access Journals (Sweden)

    Danping Wang


    Full Text Available Porous tungsten oxide/copper tungstate (WO3/CuWO4 composite thin films were fabricated via a facile in situ conversion method, with a polymer templating strategy. Copper nitrate (Cu(NO32 solution with the copolymer surfactant Pluronic®F-127 (Sigma-Aldrich, St. Louis, MO, USA, generic name, poloxamer 407 was loaded onto WO3 substrates by programmed dip coating, followed by heat treatment in air at 550 °C. The Cu2+ reacted with the WO3 substrate to form the CuWO4 compound. The composite WO3/CuWO4 thin films demonstrated improved photoelectrochemical (PEC performance over WO3 and CuWO4 single phase photoanodes. The factors of light absorption and charge separation efficiency of the composite and two single phase films were investigated to understand the reasons for the PEC enhancement of WO3/CuWO4 composite thin films. The photocurrent was generated from water splitting as confirmed by hydrogen and oxygen gas evolution, and Faradic efficiency was calculated based on the amount of H2 produced. This work provides a low-cost and controllable method to prepare WO3-metal tungstate composite thin films, and also helps to deepen the understanding of charge transfer in WO3/CuWO4 heterojunction.

  13. Angle resolved photoemission spectroscopy reveals spin charge separation in metallic MoSe2 grain boundary. (United States)

    Ma, Yujing; Diaz, Horacio Coy; Avila, José; Chen, Chaoyu; Kalappattil, Vijaysankar; Das, Raja; Phan, Manh-Huong; Čadež, Tilen; Carmelo, José M P; Asensio, Maria C; Batzill, Matthias


    Material line defects are one-dimensional structures but the search and proof of electron behaviour consistent with the reduced dimension of such defects has been so far unsuccessful. Here we show using angle resolved photoemission spectroscopy that twin-grain boundaries in the layered semiconductor MoSe2 exhibit parabolic metallic bands. The one-dimensional nature is evident from a charge density wave transition, whose periodicity is given by kF/π, consistent with scanning tunnelling microscopy and angle resolved photoemission measurements. Most importantly, we provide evidence for spin- and charge-separation, the hallmark of one-dimensional quantum liquids. Our studies show that the spectral line splits into distinctive spinon and holon excitations whose dispersions exactly follow the energy-momentum dependence calculated by a Hubbard model with suitable finite-range interactions. Our results also imply that quantum wires and junctions can be isolated in line defects of other transition metal dichalcogenides, which may enable quantum transport measurements and devices.

  14. Interfacial charge separation and photovoltaic efficiency in Fe(ii)-carbene sensitized solar cells. (United States)

    Pastore, Mariachiara; Duchanois, Thibaut; Liu, Li; Monari, Antonio; Assfeld, Xavier; Haacke, Stefan; Gros, Philippe C


    The first combined theoretical and photovoltaic characterization of both homoleptic and heteroleptic Fe(ii)-carbene sensitized photoanodes in working dye sensitized solar cells (DSSCs) has been performed. Three new heteroleptic Fe(ii)-NHC dye sensitizers have been synthesized, characterized and tested. Despite an improved interfacial charge separation in comparison to the homoleptic compounds, the heteroleptic complexes did not show boosted photovoltaic performances. The ab initio quantitative analysis of the interfacial electron and hole transfers and the measured photovoltaic data clearly evidenced fast recombination reactions for heteroleptics, even associated with un unfavorable directional electron flow, and hence slower injection rates, in the case of homoleptics. Notably, quantum mechanics calculations revealed that deprotonation of the not anchored carboxylic function in the homoleptic complex can effectively accelerate the electron injection rate and completely suppress the electron recombination to the oxidized dye. This result suggests that introduction of strong electron-donating substituents on the not-anchored carbene ligand in heteroleptic complexes, in such a way of mimicking the electronic effects of the carboxylate functionality, should yield markedly improved interfacial charge generation properties. The present results, providing for the first time a detailed understanding of the interfacial electron transfers and photovoltaic characterization in Fe(ii)-carbene sensitized solar cells, open the way to a rational molecular engineering of efficient iron-based dyes for photoelectrochemical applications.

  15. The Impact of Donor-Acceptor Phase Separation on the Charge Carrier Dynamics in pBTTT:PCBM Photovoltaic Blends

    KAUST Repository

    Gehrig, Dominik W.


    The effect of donor–acceptor phase separation, controlled by the donor–acceptor mixing ratio, on the charge generation and recombination dynamics in pBTTT-C14:PC70BM bulk heterojunction photovoltaic blends is presented. Transient absorption (TA) spectroscopy spanning the dynamic range from pico- to microseconds in the visible and near-infrared spectral regions reveals that in a 1:1 blend exciton dissociation is ultrafast; however, charges cannot entirely escape their mutual Coulomb attraction and thus predominantly recombine geminately on a sub-ns timescale. In contrast, a polymer:fullerene mixing ratio of 1:4 facilitates the formation of spatially separated, that is free, charges and reduces substantially the fraction of geminate charge recombination, in turn leading to much more efficient photovoltaic devices. This illustrates that spatially extended donor or acceptor domains are required for the separation of charges on an ultrafast timescale (<100 fs), indicating that they are not only important for efficient charge transport and extraction, but also critically influence the initial stages of free charge carrier formation.

  16. The impact of donor-acceptor phase separation on the charge carrier dynamics in pBTTT:PCBM photovoltaic blends. (United States)

    Gehrig, Dominik W; Howard, Ian A; Sweetnam, Sean; Burke, Timothy M; McGehee, Michael D; Laquai, Frédéric


    The effect of donor-acceptor phase separation, controlled by the donor-acceptor mixing ratio, on the charge generation and recombination dynamics in pBTTT-C14:PC70 BM bulk heterojunction photovoltaic blends is presented. Transient absorption (TA) spectroscopy spanning the dynamic range from pico- to microseconds in the visible and near-infrared spectral regions reveals that in a 1:1 blend exciton dissociation is ultrafast; however, charges cannot entirely escape their mutual Coulomb attraction and thus predominantly recombine geminately on a sub-ns timescale. In contrast, a polymer:fullerene mixing ratio of 1:4 facilitates the formation of spatially separated, that is free, charges and reduces substantially the fraction of geminate charge recombination, in turn leading to much more efficient photovoltaic devices. This illustrates that spatially extended donor or acceptor domains are required for the separation of charges on an ultrafast timescale (<100 fs), indicating that they are not only important for efficient charge transport and extraction, but also critically influence the initial stages of free charge carrier formation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Engineering Hydrogen Bonding Interaction and Charge Separation in Bio-Polymers for Green Lubrication. (United States)

    Mu, Liwen; Shi, Yijun; Hua, Jing; Zhuang, Wei; Zhu, Jiahua


    Synthetic additives are widely used in lubricants nowadays to upgrade lubrication properties. The potential of integrating sustainable components in modern lubricants has rarely been studied yet. In this work, two sustainable resources lignin and gelatin have been synergistically incorporated into ethylene glycol (EG), and their tribological properties were systematically investigated. The abundant hydrogen bonding sites in lignin and gelatin as well as their interchain interaction via hydrogen bonding play the dominating roles in tuning the physicochemical properties of the mixture and improving lubricating properties. Moreover, the synergistic combination of lignin and gelatin induces charge separation of gelatin that enables its preferable adsorption on the friction surface through electrostatic force and forms a robust lubrication layer. This layer will be strengthened by lignin through the interpolymer chain hydrogen bonding. At an optimized lignin:gelatin mass ratio of 1:1 and 19 wt % loading of each in EG, the friction coefficient can be greatly stabilized and the wear loss was reduced by 89% compared to pure EG. This work presents a unique synergistic phenomenon between gelatin and lignin, where hydrogen bonding and change separation are revealed as the key factor that bridges the individual components and improves overall lubricating properties.

  18. Rice Photosynthetic Productivity and PSII Photochemistry under Nonflooded Irrigation

    Directory of Open Access Journals (Sweden)

    Haibing He


    Full Text Available Nonflooded irrigation is an important water-saving rice cultivation technology, but little is known on its photosynthetic mechanism. The aims of this work were to investigate photosynthetic characteristics of rice during grain filling stage under three nonflooded irrigation treatments: furrow irrigation with plastic mulching (FIM, furrow irrigation with nonmulching (FIN, and drip irrigation with plastic mulching (DI. Compared with the conventional flooding (CF treatment, those grown in the nonflooded irrigation treatments showed lower net photosynthetic rate (PN, lower maximum quantum yield (Fv/Fm, and lower effective quantum yield of PSII photochemistry (ΦPSII. And the poor photosynthetic characteristics in the nonflooded irrigation treatments were mainly attributed to the low total nitrogen content (TNC. Under non-flooded irrigation, the PN, Fv/Fm, and ΦPSII significantly decreased with a reduction in the soil water potential, but these parameters were rapidly recovered in the DI and FIM treatments when supplementary irrigation was applied. Moreover, The DI treatment always had higher photosynthetic productivity than the FIM and FIN treatments. Grain yield, matter translocation, and dry matter post-anthesis (DMPA were the highest in the CF treatment, followed by the DI, FIM, and FIN treatments in turn. In conclusion, increasing nitrogen content in leaf of rice plants could be a key factor to improve photosynthetic capacity in nonflooded irrigation.

  19. Femtosecond charge separation in dry films of reaction centers of Rhodobacter sphaeroides and Chloroflexus aurantiacus. (United States)

    Yakovlev, A G; Khmelnitsky, A Yu; Shuvalov, V A


    In this work, the influence of the crystallographic water on electron transfer between primary donor P and acceptor B(A) was studied in reaction centers (RCs) of the purple bacterium Rhodobacter sphaeroides and the green bacterium Chloroflexus aurantiacus. For this purpose, time constants and oscillations of charge separation kinetics are compared between dry film RCs and RCs in glycerol-water buffer at 90 K. A common result of the drying of Rba. sphaeroides and Cfx. aurantiacus RCs is slowing of the charge separation process, decrease in amplitude of the oscillatory components of the kinetics, and the depletion of its spectrum. Thus, the major time constant of stimulated emission decay of P* bacteriochlorophyll dimer at 940 nm is increased from 1.1 psec for water-containing Rba. sphaeroides RCs to 1.9 psec for dry films of Rba. sphaeroides RCs. An analogous increase from 3.5 to 4.2 psec takes place in Cfx. aurantiacus RCs. In dry films of Rba. sphaeroides RCs, the amplitude of coherent oscillations of the absorption band of monomeric bacteriochlorophyll B(A)(-) at 1020 nm is 1.8 times less for the 130-cm(-1) component and 2.3 times less for the 32-cm(-1) component than the analogous amplitudes for water-containing RCs. Measurements in the analogous band of Cfx. aurantiacus RCs show that strong decrease (~5-10 times) of the B(A)(-) absorption band and strong slowing (from ~0.8 to ~3 psec) of B(A)(-) accumulation together with ~3-fold decrease in oscillation amplitude occurs on drying of these RCs. The overtones of the 32-cm(-1) component disappeared from the oscillations of the kinetics at 940 and 1020-1028 nm after drying of the Rba. sphaeroides and Cfx. aurantiacus RCs. The results are in agreement with the results for GM203L mutant of Rba. sphaeroides, in which the HOH55 water molecule is sterically removed, and with the results for dry films of pheophytin-modified RCs of Rba. sphaeroides R-26 and for YM210W and YM210L Rba. sphaeroides mutant RCs. The data are

  20. Efficient charge separation in Li(+) @C60 supramolecular complexes with electron donors. (United States)

    Kawashima, Yuki; Ohkubo, Kei; Fukuzumi, Shunichi


    Lithium-ion-encapsulated fullerene (Li(+) @C60 ) exhibits greatly enhanced reactivity in photoinduced electron-transfer reduction with electron donors compared with pristine C60 . The enhanced reactivity of Li(+) @C60 results from the more positive one-electron reduction potential of Li(+) @C60 (+0.14 V versus a standard calomel electrode (SCE)) than that of C60 (-0.43 V versus SCE), whereas the reorganization energy of electron transfer of Li(+) @C60 (1.01 eV) becomes larger than that of C60 (0.73 eV) because of the change in electrostatic interactions of encapsulated Li(+) upon electron transfer. Li(+) @C60 can form strong supramolecular complexes with various anionic electron donors through electrostatic interactions. Li(+) @C60 can also form strong supramolecular π complexes with various electron donors, such as cyclic porphyrin dimers, corannulene, and crown ether fused monopyrrolotetrathiafulvalenes. Photoinduced electron transfer from electron donors to Li(+) @C60 afforded long-lived charge-separated states of supramolecular complexes between electron donors and Li(+) @C60 . A photoelectrochemical solar cell composed of supramolecular nanoclusters of Li(+) @C60 and zinc sulfonated meso-tetraphenylporphyrin exhibits significant enhancement in the photoelectrochemical performance than that of the reference system containing only a single component. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiangyang, E-mail:, E-mail:; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong, E-mail:, E-mail: [Institute of Microsystems Physics and School of Physics and Electronics, Henan University, Kaifeng 475004 (China)


    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn{sub 2}SnO{sub 4} nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future.

  2. Femtosecond phase of charge separation in reaction centers of Chloroflexus aurantiacus. (United States)

    Yakovlev, A G; Shkuropatova, T A; Vasilieva, L G; Shkuropatov, A Ya; Shuvalov, V A


    Difference absorption spectroscopy with temporal resolution of approximately 20 fsec was used to study the primary phase of charge separation in isolated reaction centers (RCs) of Chloroflexus aurantiacus at 90 K. An ensemble of difference (light-minus-dark) absorption spectra in the 730-795 nm region measured at -0.1 to 4 psec delays relative to the excitation pulse was analyzed. Comparison with analogous data for RCs of HM182L mutant of Rhodobacter sphaeroides having the same pigment composition identified the 785 nm absorption band as the band of bacteriopheophytin Phi(B) in the B-branch. By study the bleaching of this absorption band due to formation of Phi(B)(-), it was found that a coherent electron transfer from P* to the B-branch occurs with a very small delay of 10-20 fsec after excitation of dimer bacteriochlorophyll P. Only at 120 fsec delay electron transfer from P* to the A-branch occurs with the formation of bacteriochlorophyll anion B(A)(-) absorption band at 1028 nm and the appearance of P* stimulated emission at 940 nm, as also occurs in native RCs of Rb. sphaeroides. It is concluded that a nuclear wave packet motion on the potential energy surface of P* after a 20-fsec light pulse excitation leads to the coherent formation of the P(+)Phi(B)(-) and P(+)B(A)(-) states.

  3. Strategies for Efficient Charge Separation and Transfer in Artificial Photosynthesis of Solar Fuels. (United States)

    Xu, Yuxing; Li, Ailong; Yao, Tingting; Ma, Changtong; Zhang, Xianwen; Shah, Jafar Hussain; Han, Hongxian


    Converting sunlight to solar fuels by artificial photosynthesis is an innovative science and technology for renewable energy. Light harvesting, photogenerated charge separation and transfer (CST), and catalytic reactions are the three primary steps in the processes involved in the conversion of solar energy to chemical energy (SE-CE). Among the processes, CST is the key "energy pump and delivery" step in determining the overall solar-energy conversion efficiency. Efficient CST is always high priority in designing and assembling artificial photosynthesis systems for solar-fuel production. This Review not only introduces the fundamental strategies for CST but also the combinatory application of these strategies to five types of the most-investigated semiconductor-based artificial photosynthesis systems: particulate, Z-scheme, hybrid, photoelectrochemical, and photovoltaics-assisted systems. We show that artificial photosynthesis systems with high SE-CE efficiency can be rationally designed and constructed through combinatory application of these strategies, setting a promising blueprint for the future of solar fuels. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Fundamental limits on wavelength, efficiency and yield of the charge separation triad.

    Directory of Open Access Journals (Sweden)

    Alexander Punnoose

    Full Text Available In an attempt to optimize a high yield, high efficiency artificial photosynthetic protein we have discovered unique energy and spatial architecture limits which apply to all light-activated photosynthetic systems. We have generated an analytical solution for the time behavior of the core three cofactor charge separation element in photosynthesis, the photosynthetic cofactor triad, and explored the functional consequences of its makeup including its architecture, the reduction potentials of its components, and the absorption energy of the light absorbing primary-donor cofactor. Our primary findings are two: First, that a high efficiency, high yield triad will have an absorption frequency more than twice the reorganization energy of the first electron transfer, and second, that the relative distance of the acceptor and the donor from the primary-donor plays an important role in determining the yields, with the highest efficiency, highest yield architecture having the light absorbing cofactor closest to the acceptor. Surprisingly, despite the increased complexity found in natural solar energy conversion proteins, we find that the construction of this central triad in natural systems matches these predictions. Our analysis thus not only suggests explanations for some aspects of the makeup of natural photosynthetic systems, it also provides specific design criteria necessary to create high efficiency, high yield artificial protein-based triads.

  5. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures (United States)

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong


    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn2SnO4 nanowires/Cu4Bi4S9 (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future.

  6. The influence of microstructure on charge separation dynamics in organic bulk heterojunction materials for solar cell applications

    KAUST Repository

    Scarongella, Mariateresa


    Light-induced charge formation is essential for the generation of photocurrent in organic solar cells. In order to gain a better understanding of this complex process, we have investigated the femtosecond dynamics of charge separation upon selective excitation of either the fullerene or the polymer in different bulk heterojunction blends with well-characterized microstructure. Blends of the pBTTT and PBDTTPD polymers with PCBM gave us access to three different scenarios: either a single intermixed phase, an intermixed phase with additional pure PCBM clusters, or a three-phase microstructure of pure polymer aggregates, pure fullerene clusters and intermixed regions. We found that ultrafast charge separation (by electron or hole transfer) occurs predominantly in intermixed regions, while charges are generated more slowly from excitons in pure domains that require diffusion to a charge generation site. The pure domains are helpful to prevent geminate charge recombination, but they must be sufficiently small not to become exciton traps. By varying the polymer packing, backbone planarity and chain length, we have shown that exciton diffusion out of small polymer aggregates in the highly efficient PBDTTPD:PCBM blend occurs within the same chain and is helped by delocalization. This journal is © the Partner Organisations 2014.

  7. Ultrafast photoinduced charge separation in naphthalene diimide based multichromophoric systems in liquid solutions and in a lipid membrane. (United States)

    Banerji, Natalie; Fürstenberg, Alexandre; Bhosale, Sheshanath; Sisson, Adam L; Sakai, Naomi; Matile, Stefan; Vauthey, Eric


    The photophysical properties of multichromophoric systems consisting of eight red or blue naphthalene diimides (NDIs) covalently attached to a p-octiphenyl scaffold, as well as a blue bichromophoric system with a biphenyl scaffold, have been investigated in detail using femtosecond time-resolved spectroscopy. The blue octachromophoric systems have been recently shown to self-assemble as supramolecular tetramers in lipid bilayer membranes and to enable generation of a transmembrane proton gradient upon photoexcitation ( Bhosale, S. ; Sisson, A. L. ; Talukdar, P. ; Fürstenberg, A. ; Banerji, N. ; Vauthey, E. ; Bollot, G. ; Mareda, J. ; Röger, C. ; Würthner, F. ; Sakai, N. ; Matile, S. Science 2006, 313, 84 ). A strong reduction of the fluorescence quantum yield was observed when going from the single NDI units to the multichromophoric systems in methanol, the effect being even stronger in a vesicular lipid membrane. Fluorescence up-conversion measurements reveal ultrafast self-quenching in the multichromophoric systems, whereas the formation of the NDI radical anion, evidenced by transient absorption measurements, points to the occurrence of photoinduced charge separation. The location of the positive charge could not be established unambiguously from the transient absorption measurements, but energetic considerations indicate that charge separation should occur between two NDI units in the blue systems, whereas both an NDI unit and the p-octiphenyl scaffold could act as electron donor in the red system. The lifetime of the charge-separated state was found to increase from 22 to 45 ps by going from the bi- to the octachromophoric blue systems in methanol, while a 400 ps decay component was observed in the lipid membrane. This lifetime lengthening is explained in terms of charge migration that is most efficient when the octachromophoric systems are assembled as supramolecular tetramers in the lipid membrane. Furthermore, the average charge-separated state lifetime

  8. Photogeneration of two reduction-active charge-separated states in a hybrid crystal of polyoxometalates and naphthalene diimides. (United States)

    Liu, Jian-Jun; Wang, Yao; Lin, Mei-Jin; Huang, Chang-Cang; Dai, Wen-Xin


    The combination of naphthalene diimide tectons with zinc cations in the presence of polyanions, Mo6O19(2-), leads to a hybrid crystal composed of two-dimensional porous coordination networks and polyoxometalates, which can generate two kinds of long-lived charge-separated states for the reduction reactions upon irradiation.

  9. Influence of core-substitution on the ultrafast charge separation and recombination in arylamino core-substituted naphthalene diimides (United States)

    Pugliesi, Igor; Megerle, Uwe; Suraru, Sabin-Lucian; Würthner, Frank; Riedle, Eberhard; Lochbrunner, Stefan


    We study the charge separation and recombination of two arylamino core-substituted naphthalene diimides by transient absorption. Both compounds show a 3 ps relaxation from the initially excited partial to the full charge transfer state. Quantum chemical calculations show that this process is associated with a twisting of the arylamino substituent. In the twisted conformation the energy gap between ground and excited state is 0.7 eV for two amino core-substituents and 0.5 eV for one amino and one chloro core-substituent. The larger energy gap leads to a six-fold increase in the lifetime of the fully charge separated state from 11 to 70 ps.

  10. Liquid crystal-enabled electro-osmosis through spatial charge separation in distorted regions as a novel mechanism of electrokinetics (United States)

    Lazo, Israel; Peng, Chenhui; Xiang, Jie; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.


    Electrically controlled dynamics of fluids and particles at microscales is a fascinating area of research with applications ranging from microfluidics and sensing to sorting of biomolecules. The driving mechanisms are electric forces acting on spatially separated charges in an isotropic medium such as water. Here, we demonstrate that anisotropic conductivity of liquid crystals enables new mechanism of highly efficient electro-osmosis rooted in space charging of regions with distorted orientation. The electric field acts on these distortion-separated charges to induce liquid crystal-enabled electro-osmosis. Their velocities grow with the square of the field, which allows one to use an alternating current field to drive steady flows and to avoid electrode damage. Ionic currents in liquid crystals that have been traditionally considered as an undesirable feature in displays, offer a broad platform for versatile applications such as liquid crystal-enabled electrokinetics, micropumping and mixing.

  11. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC. (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M


    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

  12. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Dieter Konrad Michael


    Closely packed nanocrystal systems have been investigated in this thesis with respect to charge separation by charge carrier tunneling. Clustered and layered samples have been analyzed using PL-measurements and SPV-methods. The most important findings are reviewed in the following. A short outlook is also provided for potential further aspects and application of the presented results. The main purpose of this thesis was to find and quantify electronic tunneling transfer in closely packed self-assembled nanocrystal structures presenting quantum mechanical barriers of about 1 nm width. We successfully used hybrid assemblies of CdTe and CdSe nanocrystals where the expected type II alignment between CdTe and CdSe typically leads to a concentration of electrons in CdSe and holes in CdTe nanocrystals. We were able to prove the charge selectivity of the CdTe-CdSe nanocrystal interface which induces charge separation. We mainly investigated the effects related to the electron transfer from CdTe to CdSe nanocrystals. Closely packing was achieved by two independent methods: the disordered colloidal clustering in solution and the layered assembly on dry glass substrates. Both methods lead to an inter-particle distance of about 1 nm of mainly organic material which acts as a tunneling barrier. PL-spectroscopy was applied. The PL-quenching of the CdTe nanocrystals in hybrid assemblies indicates charge separation by electron transfer from CdTe to CdSe nanocrystals. A maximum quenching rate of up to 1/100 ps was measured leading to a significant global PL-quenching of up to about 70 % for the CdTe nanocrystals. It was shown that charge separation dynamics compete with energy transfer dynamics and that charge separation typically dominates. The quantum confinement effect was used to tune the energetic offset between the CdTe and CdSe nanocrystals. We thus observe a correlation of PL-quenching and offset of the energy states for the electron transfer. The investigated PL

  13. The impact of long-range electron-hole interaction on the charge separation yield of molecular photocells (United States)

    Nemati Aram, Tahereh; Ernzerhof, Matthias; Asgari, Asghar; Mayou, Didier


    We discuss the effects of charge carrier interaction and recombination on the operation of molecular photocells. Molecular photocells are devices where the energy conversion process takes place in a single molecular donor-acceptor complex attached to electrodes. Our investigation is based on the quantum scattering theory, in particular on the Lippmann-Schwinger equation; this minimizes the complexity of the problem while providing useful and non-trivial insight into the mechanism governing photocell operation. In this study, both exciton pair creation and dissociation are treated in the energy domain, and therefore there is access to detailed spectral information, which can be used as a framework to interpret the charge separation yield. We demonstrate that the charge carrier separation is a complex process that is affected by different parameters, such as the strength of the electron-hole interaction and the non-radiative recombination rate. Our analysis helps to optimize the charge separation process and the energy transfer in organic solar cells and in molecular photocells.

  14. Extending Long-lived Charge Separation Between Donor and Acceptor Blocks in Novel Copolymer Architectures Featuring a Sensitizer Core. (United States)

    Schroot, Robert; Schlotthauer, Tina; Dietzek, Benjamin; Jäger, Michael; Schubert, Ulrich S


    A bifunctional RuII photosensitizer unit was decorated with one n- and one p-type polymer chain to form precisely controlled hierarchical copolymer-type architectures for light-induced charge separation. The applied modular chemistry-on-the-complex strategy benefits from separately prepared building blocks and their orthogonal linkage in the two final assembly steps. Upon visible light absorption, electron transfer is initiated between the conjugated poly(3,6-carbazole) chain and the styrenic poly(naphthalene diimide) segments. Steady-state and time-resolved spectroscopy show complete charge separation within a few nanoseconds (>95 % efficiency) persisting several tens of microseconds. The recombination is significantly reduced in comparison to low-molecular model systems or to non-conjugated congeners, reflecting the higher charge mobility in conjugated polymers. In summary, the modularity of the presented approach is expected to serve as a versatile platform to tailor the interface between the charge transport domains in a systematic fashion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Quantum Coherence Facilitates Efficient Charge Separation at a MoS2/MoSe2 van der Waals Junction. (United States)

    Long, Run; Prezhdo, Oleg V


    Two-dimensional transition metal dichalcogenides (MX2, M = Mo, W; X = S, Se) hold great potential in optoelectronics and photovoltaics. To achieve efficient light-to-electricity conversion, electron-hole pairs must dissociate into free charges. Coulomb interaction in MX2 often exceeds the charge transfer driving force, leading one to expect inefficient charge separation at a MX2 heterojunction. Experiments defy the expectation. Using time-domain density functional theory and nonadiabatic (NA) molecular dynamics, we show that quantum coherence and donor-acceptor delocalization facilitate rapid charge transfer at a MoS2/MoSe2 interface. The delocalization is larger for electron than hole, resulting in longer coherence and faster transfer. Stronger NA coupling and higher acceptor state density accelerate electron transfer further. Both electron and hole transfers are subpicosecond, which is in agreement with experiments. The transfers are promoted primarily by the out-of-plane Mo-X modes of the acceptors. Lighter S atoms, compared to Se, create larger NA coupling for electrons than holes. The relatively slow relaxation of the "hot" hole suggests long-distance bandlike transport, observed in organic photovoltaics. The electron-hole recombination is notably longer across the MoS2/MoSe2 interface than in isolated MoS2 and MoSe2, favoring long-lived charge separation. The atomistic, time-domain studies provide valuable insights into excitation dynamics in two-dimensional transition metal dichalcogenides.

  16. Determination of the excitation migration time in Photosystem II - Consequences for the membrane organization and charge separation parameters

    NARCIS (Netherlands)

    Broess, Koen; Trinkunas, Gediminas; van Hoek, Arie; Croce, Roberta; van Amerongen, Herbert

    The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

  17. Theoretical Study of the Charge-Transfer State Separation within Marcus Theory

    DEFF Research Database (Denmark)

    Volpi, Riccardo; Nassau, Racine; Nørby, Morten Steen


    We study, within Marcus theory, the possibility of the charge-transfer (CT) state splitting at organic interfaces and a subsequent transport of the free charge carriers to the electrodes. As a case study we analyze model anthracene-C60 interfaces. Kinetic Monte Carlo (KMC) simulations on the cold...

  18. Direct Observation of Charge Separation on Anatase TiO2 Crystals with Selectively Etched {001} Facets. (United States)

    Liu, Xiaogang; Dong, Guojun; Li, Shaopeng; Lu, Gongxuan; Bi, Yingpu


    Synchronous illumination X-ray photoelectron spectroscopy (SIXPS) was employed for the first time to directly identify the photogenerated charge separation and transfer on anatase TiO2 single-crystals with selectively etched {001} facets. More specifically, for the TiO2 crystals with intact {001} and {101} facets, most of photogenerated charge carriers rapidly recombined, and no evident electron-hole separation was detected. With selectively etching on {001} facets, high efficient charge separation via hole transfer to titanium and electron to oxygen was clearly observed. However, when the {001} facets were completely etched into a hollow structure, the recombination for photogenerated electron-hole pairs would dominate again. These demonstrations clearly reveal that the appropriate corrosion on {001} facets could facilitate more efficient electron-hole separation and transfer. As expected, the optimized TiO2 microcrystals with etched {001} facets could achieve a hydrogen generation rate of 74.3 μmol/h/g, which is nearly 7 times higher than the intact-TiO2 crystals.

  19. Accumulative charge separation for solar fuels production: coupling light-induced single electron transfer to multielectron catalysis. (United States)

    Hammarström, Leif


    The conversion and storage of solar energy into a fuel holds promise to provide a significant part of the future renewable energy demand of our societies. Solar energy technologies today generate heat or electricity, while the large majority of our energy is used in the form of fuels. Direct conversion of solar energy to a fuel would satisfy our needs for storable energy on a large scale. Solar fuels can be generated by absorbing light and converting its energy to chemical energy by electron transfer leading to separation of electrons and holes. The electrons are used in the catalytic reduction of a cheap substrate with low energy content into a high-energy fuel. The holes are filled by oxidation of water, which is the only electron source available for large scale solar fuel production. Absorption of a single photon typically leads to separation of a single electron-hole pair. In contrast, fuel production and water oxidation are multielectron, multiproton reactions. Therefore, a system for direct solar fuel production must be able to accumulate the electrons and holes provided by the sequential absorption of several photons in order to complete the catalytic reactions. In this Account, the process is termed accumulative charge separation. This is considerably more complicated than charge separation on a single electron level and needs particular attention. Semiconductor materials and molecular dyes have for a long time been optimized for use in photovoltaic devices. Efforts are made to develop new systems for light harvesting and charge separation that are better optimized for solar fuel production than those used in the early devices presented so far. Significant progress has recently been made in the discovery and design of better homogeneous and heterogeneous catalysts for solar fuels and water oxidation. While the heterogeneous ones perform better today, molecular catalysts based on transition metal complexes offer much greater tunability of electronic and

  20. The Separation Measurement of P -Hit and N -Hit Charge Sharing With an ``S-Like'' Inverter Chains Test Structure (United States)

    Huang, Pengcheng; Chen, Shuming; Chen, Jianjun; Liang, Bin; Song, Ruiqiang


    In this paper, an “S-like” inverter chains (SLIC) test structure is designed for the separation measurement of N-hit and P-hit charge sharing. The heavy-ion experiments were performed in 65-nm bulk dual-well and triple-well technology, and the N-hit and P-hit pulse quenching (PQ) span is attained. The results has verified the ability of the “SLIC” test structure to characterize P-hit and N-hit PQ, and the results also indicate that the N+ deep well can enhance the action extent of N-hit charge sharing greatly though it will reduce the action extent P-hit charge sharing.

  1. Direct Imaging of Highly Anisotropic Photogenerated Charge Separations on Different Facets of a Single BiVO4 Photocatalyst. (United States)

    Zhu, Jian; Fan, Fengtao; Chen, Ruotian; An, Hongyu; Feng, Zhaochi; Li, Can


    Spatially resolved surface photovoltage spectroscopy (SRSPS) was employed to obtain direct evidence for highly anisotropic photogenerated charge separation on different facets of a single BiVO4 photocatalyst. Through the controlled synthesis of a single crystal with preferentially exposed {010} facets, highly anisotropic photogenerated hole transfer to the {011} facet of single BiVO4 crystals was observed. The surface photovoltage signal intensity on the {011} facet was 70 times stronger than that on the {010} facets. The influence of the built-in electric field in the space charge region of different facets on the anisotropic photoinduced charge transfer in a single semiconductor crystal is revealed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Aniline dimers and trimers as model compounds for polyaniline: steric control of charge separation properties (United States)

    Kapelle, Sabine; Rettig, Wolfgang; Lapouyade, René


    The photophysical properties of several derivatives of 4-aminodiphenylamine (ADPA), model compounds of aniline dimers and trimers are investigated. Several compounds show dual fluorescence with a charge transfer (CT) component with a significantly reduced fluorescence rate constant which can be suppressed by bridging and enhanced by sterically hindering substituents, in close similarity to the compounds showing twisted intramolecular charge transfer (TICT). The relation to polyaniline (PANI) conductivity is also discussed.

  3. Charge Separation Mechanisms in Ordered Films of Self-Assembled Donor–Acceptor Dyad Ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Logsdon, Jenna L.; Hartnett, Patrick E.; Nelson, Jordan N.; Harris, Michelle A.; Marks, Tobin J.; Wasielewski, Michael R. (NWU)


    Orthogonal attachment of polar and nonpolar side-chains to a zinc porphyrin-perylenediimide dyad (ZnP-PDI, 1a) is shown to result in self-assembly of ordered supramolecular ribbons in which the ZnP and PDI molecules form segregated π-stacked columns. Following photoexcitation of the ordered ribbons, ZnP+•-PDI–• radical ion pairs form in <200 fs and subsequently produce a 30 ± 3% yield of free charge carriers that live for about 100 μs. Elongating the side chains on ZnP and PDI in 1b enhances the order of the films, but does not result in an increase in free charge carrier yield. In addition, this yield is independent of temperature, free energy of reaction, and the ZnP-PDI distance in the covalent dyad. These results suggest that the free charge carrier yield in this system is not limited by a bound charge transfer (CT) state or promoted by a vibronically hot CT state. Instead, it is likely that π-stacking of the segregated donors and acceptors within the ribbons results in delocalization of the charges following photoexcitation, allowing them to overcome Coulombic attraction and generate free charge carriers.

  4. Photoinduced multistep charge separation in a heteroleptic Cu(I) bis(phenanthroline)-based donor-chromophore-acceptor triad. (United States)

    Lazorski, Megan S; Gest, Riley H; Elliott, C Michael


    A molecular triad assembly consisting of an electron donor, a bis(phenanthroline)copper(I) chromophore, and an electron acceptor has been prepared. Under visible-light excitation, this assembly undergoes efficient (ca. 50%) photoinduced, multistep formation of a diradical cation charge-separated state that has a lifetime of >100 ns and stores >1.0 eV of energy. This system constitutes an earth-abundant functional analogue of related Ru(bpy)(3) triad systems.

  5. Enhanced photocatalytic performance of Ag2O/BiOF composite photocatalysts originating from efficient interfacial charge separation (United States)

    Yang, Mei; Yang, Qi; Zhong, Junbo; Huang, Shengtian; Li, Jianzhang; Song, Jiabo; Burda, Clemens


    Previous studies have well established that the photocatalytic performance of BiOF is greatly inhibited by its inherent drawbacks, which are the wide band gap and high recombination of photo-generated charge carriers. Therefore, it is necessary to promote the photocatalytic activity of BiOF. In this work, a series of novel Ag2O/BiOF composites were prepared by a facile precipitation method and characterized by X-ray diffractometry (XRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), surface photovoltage (SPV) spectroscopy, and electron spin-resonance (ESR) spectroscopy. The photocatalytic characteristics of Rhodamine B (RhB) discoloration under simulated sunlight and visible-light irradiation were studied. The results revealed that the sample with 1.0% molar ratio of Ag/Bi displayed the best photocatalytic performance towards RhB discoloration and all the studied composites in this work displayed a higher photocatalytic activity than the bare BiOF. Based on the results of ;band edge potential; of Ag2O and BiOF, SPV and ESR, charge separation and transportation mechanisms are suggested. Under simulated sunlight illumination, the charge separation and transport mechanism of the photo-induced charge pairs followed a Z-scheme.

  6. Spontaneous Charge Separation and Sublimation Processes are Ubiquitous in Nature and in Ionization Processes in Mass Spectrometry (United States)

    Trimpin, Sarah; Lu, I.-Chung; Rauschenbach, Stephan; Hoang, Khoa; Wang, Beixi; Chubatyi, Nicholas D.; Zhang, Wen-Jing; Inutan, Ellen D.; Pophristic, Milan; Sidorenko, Alexander; McEwen, Charles N.


    Ionization processes have been discovered by which small and large as well as volatile and nonvolatile compounds are converted to gas-phase ions when associated with a matrix and exposed to sub-atmospheric pressure. Here, we discuss experiments further defining these simple and unexpected processes. Charge separation is found to be a common process for small molecule chemicals, solids and liquids, passed through an inlet tube from a higher to a lower pressure region, with and without heat applied. This charge separation process produces positively- and negatively-charged particles with widely different efficiencies depending on the compound and its physical state. Circumstantial evidence is presented suggesting that in the new ionization process, charged particles carry analyte into the gas phase, and desolvation of these particles produce the bare ions similar to electrospray ionization, except that solid particles appear likely to be involved. This mechanistic proposition is in agreement with previous theoretical work related to ion emission from ice. [Figure not available: see fulltext.

  7. Improvement of charge separation in TiO{sub 2} by its modification with different tungsten compounds

    Energy Technology Data Exchange (ETDEWEB)

    Tryba, B., E-mail:; Tygielska, M.; Grzeskowiak, M.; Przepiorski, J.


    Highlights: • Ammonium m-tungstate doped to TiO{sub 2} highly improved charge separation in TiO{sub 2}. • Negative electrokinetic potential of TiO{sub 2} facilitates holes migration to its surface. • Fast migration of holes to TiO{sub 2} surfaces increased yield of OH radicals formation. • Adsorption of dyes on photocatalyst increased its decomposition under visible light. - Abstract: Three different tungsten precursors were used for TiO{sub 2} modification: H{sub 2}WO{sub 4}, WO{sub 2}, and ammonium m-tungstate. It was proved that modification of TiO{sub 2} with tungsten compounds enhanced its photocatalytic activity through the improvement of charge separation. This effect was obtained by coating of TiO{sub 2} particles with tungsten compound, which changed their surficial electrokinetical potential from positive onto negative. The most efficient tungsten compound, which caused enhanced separation of free carriers was ammonium m-tungstate (AMT). Two dyes with different ionic potential were used for the photocatalytic decomposition. It appeared that cationic dye—Methylene Blue was highly adsorbed on the negatively charged surface of TiO{sub 2} modified by AMT and decomposed, however this photocatalyst was quickly deactivated whereas anionic dye—acid red was better adsorbed on the less acidic surface of TiO{sub 2} and was rapidly decomposed with almost the same rate in the five following cycles.

  8. Molecular approaches to solar energy conversion: the energetic cost of charge separation from molecular-excited states. (United States)

    Durrant, James R


    This review starts with a brief overview of the technological potential of molecular-based solar cell technologies. It then goes on to focus on the core scientific challenge associated with using molecular light-absorbing materials for solar energy conversion, namely the separation of short-lived, molecular-excited states into sufficiently long-lived, energetic, separated charges capable of generating an external photocurrent. Comparisons are made between different molecular-based solar cell technologies, with particular focus on the function of dye-sensitized photoelectrochemical solar cells as well as parallels with the function of photosynthetic reaction centres. The core theme of this review is that generating charge carriers with sufficient lifetime and a high quantum yield from molecular-excited states comes at a significant energetic cost-such that the energy stored in these charge-separated states is typically substantially less than the energy of the initially generated excited state. The role of this energetic loss in limiting the efficiency of solar energy conversion by such devices is emphasized, and strategies to minimize this energy loss are compared and contrasted.

  9. High-resolution peptide mapping separations with MS-friendly mobile phases and charge-surface-modified C18. (United States)

    Lauber, Matthew A; Koza, Stephan M; McCall, Scott A; Alden, Bonnie A; Iraneta, Pamela C; Fountain, Kenneth J


    Ionic analytes, such as peptides, can be challenging to separate by reverse-phase chromatography with optimal efficiency. They tend, for instance, to exhibit poor peak shapes, particularly when eluted with mobile phases preferred for electrospray ionization mass spectrometry. We demonstrate that a novel charged-surface C18 stationary phase alleviates some of the challenges associated with reverse-phase peptide separations. This column chemistry, known as CSH (charged-surface hybrid) C18, improves upon an already robust organosilica hybrid stationary phase, BEH (ethylene-bridged hybrid) C18. Based on separations of a nine-peptide standard, CSH C18 was found to exhibit improved loadability, greater peak capacities, and unique selectivity compared to BEH C18. Its performance was also seen to be significantly less dependent on TFA-ion pairing, making it ideal for MS applications where high sensitivity is desired. These performance advantages were evaluated through application to peptide mapping, wherein CSH C18 was found to aid the development of a high-resolution, high-sensitivity LC-UV-MS peptide mapping method for the therapeutic antibody, trastuzumab. From these results, the use of a C18 stationary phase with a charged surface, such as CSH C18, holds significant promise for facilitating challenging peptide analyses.

  10. Charge-Separation Kinetics of Photoexcited Oxygen Vacancies in ZnO Nanowire Field-Effect Transistors (United States)

    Lu, Ming-Pei; Chen, Chieh-Wei; Lu, Ming-Yen


    Photoinduced atomic structural transitions of negative-U defects: neutral oxygen vacancies (VO 0 ), accompanied by lattice relaxation, can form ionized 1 + and 2 + vacancy defects in ZnO materials, giving rise to an optoelectronic phenomenon named "persistent photoconductivity," thereby limiting the applications of ZnO materials in optoelectronic fields. Nevertheless, very little is known about the kinetics of the separation-recombination interactions between an electron and an ionized oxygen vacancy, constituting a photoexcited charge pair, in nanoscale ZnO material systems, especially when considering the effect of electric fields. In this report, we describe the charge-separation kinetics of photoexcited VO 0 defects in ZnO nanowire (NW) field-effect transistor (FET) systems, examined through modulation of the surface electric field of the ZnO NW. We apply oxygen plasma treatment to tailor the doping concentration within the ZnO NWs with the goal of modulating the electric field within their surface space-charge layers. X-ray photoelectron spectroscopy and low-frequency current-noise spectroscopy are applied to identify the change in the density of oxygen-vacancy defects near the NW surface after oxygen plasma treatment. A model describing the initial stage of the photoconductance responses associated with the formation of the photoinduced ionized 1 + state of the oxygen-vacancy defects (VO + ) in the fully depleted ZnO NW FETs in the low-photoconductance regime upon UV excitation is proposed to extract the charge-separation probabilities of the photoexcited electron/VO + pair. Accordingly, the charge-separation probability increases from approximately 0.0012 to 0.042 upon increasing the electric field at the NW surface from approximately 7.5 ×106 to 5.0 ×107 V m-1 . Moreover, we employ modified Braun empirical theory to model the effect of the electric field on the charge-separation behavior of photoexcited electron/VO + pairs in ZnO NWs, obtaining a

  11. Enhanced charge separation in ternary P3HT/PCBM/CuInS2 nanocrystals hybrid solar cells. (United States)

    Lefrançois, Aurélie; Luszczynska, Beata; Pepin-Donat, Brigitte; Lombard, Christian; Bouthinon, Benjamin; Verilhac, Jean-Marie; Gromova, Marina; Faure-Vincent, Jérôme; Pouget, Stéphanie; Chandezon, Frédéric; Sadki, Saïd; Reiss, Peter


    Geminate recombination of bound polaron pairs at the donor/acceptor interface is one of the major loss mechanisms in organic bulk heterojunction solar cells. One way to overcome Coulomb attraction between opposite charge carriers and to achieve their full dissociation is the introduction of high dielectric permittivity materials such as nanoparticles of narrow band gap semiconductors. We selected CuInS2 nanocrystals of 7.4 nm size, which present intermediate energy levels with respect to poly(3-hexylthiophene) (P3HT) and Phenyl-C61-butyric acid methyl ester (PCBM). Efficient charge transfer from P3HT to nanocrystals takes place as evidenced by light-induced electron spin resonance. Charge transfer between nanocrystals and PCBM only occurs after replacing bulky dodecanethiol (DDT) surface ligands with shorter 1,2-ethylhexanethiol (EHT) ligands. Solar cells containing in the active layer a ternary blend of P3HT:PCBM:CuInS2-EHT nanocrystals in 1:1:0.5 mass ratio show strongly improved short circuit current density and a higher fill factor with respect to the P3HT:PCBM reference device. Complementary measurements of the absorption properties, external quantum efficiency and charge carrier mobility indicate that enhanced charge separation in the ternary blend is at the origin of the observed behavior. The same trend is observed for blends using the glassy polymer poly(triarylamine) (PTAA).

  12. Charge-based separation of proteins and peptides by electrically induced dynamic pH profiles. (United States)

    Brod, E; S Ben-Yosef, V; Bandhakavi, S; Sivan, U


    A new method for generating complex, dynamic pH profiles in an ampholyte-free separation channel is presented together with the theory behind its operation. The pH is modulated by an array of proton and hydroxide ion injectors placed along the separation channel. The ions generated in-situ by electrically driven water splitting across a bipolar membrane are injected to the channel in the presence of a longitudinal electric field, leading to the formation of a multi-step pH profile. Real-time control over the pH profile along the channel facilitates new dynamic separation strategies as well as steering and harvesting of focused molecules, which are both impossible with conventional separation methods. These freedoms are particularly attractive for Lab-on-a-Chip applications. The pH step-like profile alleviates one of the main hurdles of conventional isoelectric separation methods, namely, the slowing down of focused molecules as they approach their focusing spot. As a result, separation is completed within minutes for both peptides and proteins, even with low applied electric fields. We demonstrate protein and peptide separation within minutes, and resolution of ΔpI=0.2. Novel separation strategies based on spatio-temporal pH control are demonstrated as well. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Direct observation of ultrafast long-range charge separation at polymer–fullerene heterojunctions

    KAUST Repository

    Provencher, Françoise


    In polymeric semiconductors, charge carriers are polarons, which means that the excess charge deforms the molecular structure of the polymer chain that hosts it. This results in distinctive signatures in the vibrational modes of the polymer. Here, we probe polaron photogeneration dynamics at polymer:fullerene heterojunctions by monitoring its time-resolved resonance-Raman spectrum following ultrafast photoexcitation. We conclude that polarons emerge within 300 fs. Surprisingly, further structural evolution on ≤50-ps timescales is modest, indicating that the polymer conformation hosting nascent polarons is not significantly different from that near equilibrium. We interpret this as suggestive that charges are free from their mutual Coulomb potential because we would expect rich vibrational dynamics associated with charge-pair relaxation. We address current debates on the photocarrier generation mechanism at molecular heterojunctions, and our work is, to our knowledge, the first direct probe of molecular conformation dynamics during this fundamentally important process in these materials. © 2014 Macmillan Publishers Limited. All rights reserved.

  14. Virtual charge state separator as an advanced tool coupling measurements and simulations (United States)

    Yaramyshev, S.; Vormann, H.; Adonin, A.; Barth, W.; Dahl, L.; Gerhard, P.; Groening, L.; Hollinger, R.; Maier, M.; Mickat, S.; Orzhekhovskaya, A.


    A new low energy beam transport for a multicharge uranium beam will be built at the GSI High Current Injector (HSI). All uranium charge states coming from the new ion source will be injected into GSI heavy ion high current HSI Radio Frequency Quadrupole (RFQ), but only the design ions U4 + will be accelerated to the final RFQ energy. A detailed knowledge about injected beam current and emittance for pure design U4 + ions is necessary for a proper beam line design commissioning and operation, while measurements are possible only for a full beam including all charge states. Detailed measurements of the beam current and emittance are performed behind the first quadrupole triplet of the beam line. A dedicated algorithm, based on a combination of measurements and the results of advanced beam dynamics simulations, provides for an extraction of beam current and emittance values for only the U4 + component of the beam. The proposed methods and obtained results are presented.

  15. Elucidating the Ultrafast Dynamics of Photoinduced Charge Separation in Metalloporphyrin-Fullerene Dyads Across the Electromagnetic Spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.; Pápai, M.; Hirsch, A.; Jennings, G.; Kurtz, C. A.; Møller, K. B.; Lomoth, R.; Gosztola, D.; Zhang, X.; Canton, S. E.


    Metalloporphyrins are prominent building blocks in the synthetic toolbox of advanced photodriven molecular devices. When the central ion is paramagnetic, the relaxation pathways within the manifold of excited states are highly intricate so that unravelling the intramolecular energy and electron transfer processes is usually a very complex task. This fact is critically hampering the development of applications based on the enhanced coupling offered by the electronic exchange interaction. In this work, the dynamics of charge separation in a copper porphyrin-fullerene are studied with several complementary spectroscopic tools across the electromagnetic spectrum (from near infra-red to X-ray wavelengths), each of them providing specific diagnostics. Correlating the various rates clearly demonstrates that the lifetime of the photoinduced charge-separated state exceeds by about 10 fold that of the isolated photoexcited CuII porphyrin. As revealed by the spectral modifications in the XANES region, this stabilization is accompanied by a transient change in covalency around the CuII center, which is induced by an enhanced interaction with the C60 moiety. This experimental finding is further confirmed by state-of-the art calculations using DFT and TD-DFT including dispersion effects that explain the electrostatic and structural origins of this interaction, as the CuIIP cation becomes ruffled and approaches closer to the fullerene in the charge-separated state. From a methodological point of view, these results exemplify the potential of multielectron excitation features in transient X-ray spectra as future diagnostics of sub-femtosecond electronic dynamics. From a practical point of view, this work is paving the way for elucidating out-of-equilibrium electron transfer events coupled to magnetic interaction processes on their intrinsic time-scales.

  16. Polarization Energies at Organic–Organic Interfaces: Impact on the Charge Separation Barrier at Donor–Acceptor Interfaces in Organic Solar Cells

    KAUST Repository

    Ryno, Sean


    We probe the energetic landscape at a model pentacene/fullerene-C60 interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e. the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges, results in a barrier to charge separation at the pentacene-C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.

  17. Competition among Superconducting, Antiferromagnetic, and Charge Orders with Intervention by Phase Separation in the 2D Holstein-Hubbard Model (United States)

    Ohgoe, Takahiro; Imada, Masatoshi


    Using a variational Monte Carlo method, we study the competition of strong electron-electron and electron-phonon interactions in the ground state of the Holstein-Hubbard model on a square lattice. At half filling, an extended intermediate metallic or weakly superconducting (SC) phase emerges, sandwiched between antiferromagnetic and charge order (CO) insulating phases. By carrier doping into the CO insulator, the SC order dramatically increases for strong electron-phonon couplings, but is largely hampered by wide phase separation (PS) regions. Superconductivity is optimized at the border to the PS.

  18. Virtual charge state separator as an advanced tool coupling measurements and simulations

    Directory of Open Access Journals (Sweden)

    S. Yaramyshev


    Full Text Available A new low energy beam transport for a multicharge uranium beam will be built at the GSI High Current Injector (HSI. All uranium charge states coming from the new ion source will be injected into GSI heavy ion high current HSI Radio Frequency Quadrupole (RFQ, but only the design ions U^{4+} will be accelerated to the final RFQ energy. A detailed knowledge about injected beam current and emittance for pure design U^{4+} ions is necessary for a proper beam line design commissioning and operation, while measurements are possible only for a full beam including all charge states. Detailed measurements of the beam current and emittance are performed behind the first quadrupole triplet of the beam line. A dedicated algorithm, based on a combination of measurements and the results of advanced beam dynamics simulations, provides for an extraction of beam current and emittance values for only the U^{4+} component of the beam. The proposed methods and obtained results are presented.

  19. Non-destructive measurement and monitoring of separation of charged particle micro-bunches (United States)

    Zhang, H.; Konoplev, I. V.; Lancaster, A. J.; Harrison, H.; Doucas, G.; Aryshev, A.; Shevelev, M.; Terunuma, N.; Urakawa, J.


    Micro-bunched particle beams are used for a wide range of research including wakefield-based particle acceleration and tunable sources of radiation. In all applications, accurate and non-destructive monitoring of the bunch-to-bunch separation is required. With the development of femtosecond lasers, the generation of micro-bunched beams directly from a photocathode becomes routine; however, non-destructive monitoring of the separation is still a challenge. We present the results of proof-of-principle experiments conducted at the Laser Undulator Compact X-ray accelerator measuring the distance between micro-bunches via the amplitude modulation analysis of a monochromatic radiation signal. Good agreement with theoretical predictions is shown; limitations and further improvements are discussed.

  20. Universal experimental test for the role of free charge carriers in the thermal Casimir effect within a micrometer separation range (United States)

    Bimonte, G.; Klimchitskaya, G. L.; Mostepanenko, V. M.


    We propose a universal experiment to measure the differential Casimir force between a Au-coated sphere and two halves of a structured plate covered with a P-doped Si overlayer. The concentration of free charge carriers in the overlayer is chosen slightly below the critical one, for which the phase transition from dielectric to metal occurs. One half of the structured plate is insulating, while the second half is made of gold. For the former we consider two structures, one consisting of bulk high-resistivity Si and the other of a layer of SiO 2 followed by bulk high-resistivity Si. The differential Casimir force is computed within the Lifshitz theory using four approaches that have been proposed in the literature to account for the role of free charge carriers in metallic and dielectric materials interacting with quantum fluctuations. According to these approaches, Au at low frequencies is described by either the Drude or the plasma model, whereas the free charge carriers in dielectric materials at room temperature are either taken into account or disregarded. It is shown that the values of differential Casimir forces, computed in the micrometer separation range using these four approaches, are widely distinct from each other and can be easily discriminated experimentally. It is shown that for all approaches the thermal component of the differential Casimir force is sufficiently large for direct observation. The possible errors and uncertainties in the proposed experiment are estimated and its importance for the theory of quantum fluctuations is discussed.

  1. Photoinduced charge separation in an aqueous phase using nanoporous TiO{sub 2} film and a quasi-solid made of natural products

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Masao; Nomura, Tomoyo; Sasaki, Chie [Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito (Japan)


    Solar cells comprised of nanoparticulate TiO{sub 2} porous film photosensitized with an adsorbing dye have been utilized as photoinduced charge separation systems in aqueous media with the view to forming future artificial photosynthetic systems able to create fuels from solar energy and water. The photoinduced charge separation of the sensitized TiO{sub 2} cell in a quasi-solid, made from agarose or {kappa}-carrageenan, was investigated. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  2. A panchromatic hybrid crystal of iodoplumbate nanowires and J-aggregated naphthalene diimides with long-lived charge-separated states. (United States)

    Liu, Jian-Jun; Guan, Ying-Fang; Jiao, Chen; Lin, Mei-Jin; Huang, Chang-Cang; Dai, Wen-Xin


    A panchromatic hybrid crystal of anionic iodoplumbate nanowires and J-aggregated protonated naphthalene diimides has been formed through charge-assisted anion-π and lone pair-π interactions, which exhibits unusually long-lived charge-separated states even upon the irradiation of indoor lighting.

  3. Remarkable Charge Separation and Photocatalytic Efficiency Enhancement through Interconnection of TiO2 Nanoparticles by Hydrothermal Treatment. (United States)

    Ide, Yusuke; Inami, Nozomu; Hattori, Hideya; Saito, Kanji; Sohmiya, Minoru; Tsunoji, Nao; Komaguchi, Kenji; Sano, Tsuneji; Bando, Yoshio; Golberg, Dmitri; Sugahara, Yoshiyuki


    Although tremendous effort has been directed to synthesizing advanced TiO2 , it remains difficult to obtain TiO2 exhibiting a photocatalytic efficiency higher than that of P25, a benchmark photocatalyst. P25 is composed of anatase, rutile, and amorphous TiO2 particles, and photoexcited electron transfer and subsequent charge separation at the anatase-rutile particle interfaces explain its high photocatalytic efficiency. Herein, we report on a facile and rational hydrothermal treatment of P25 to selectively convert the amorphous component into crystalline TiO2 , which is deposited between the original anatase and rutile particles to increase the particle interfaces and thus enhance charge separation. This process produces a new TiO2 exhibiting a considerably enhanced photocatalytic efficiency. This method of synthesizing this TiO2 , inspired by a recently burgeoning zeolite design, promises to make TiO2 applications more feasible and effective. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation (United States)

    Thürmer, Stephan; Ončák, Milan; Ottosson, Niklas; Seidel, Robert; Hergenhahn, Uwe; Bradforth, Stephen E.; Slavíček, Petr; Winter, Bernd


    To understand the yield and patterns of damage in aqueous condensed matter, including biological systems, it is essential to identify the initial products subsequent to the interaction of high-energy radiation with liquid water. Until now, the observation of several fast reactions induced by energetic particles in water was not possible on their characteristic timescales. Therefore, some of the reaction intermediates involved, particularly those that require nuclear motion, were not considered when describing radiation chemistry. Here, through a combined experimental and theoretical study, we elucidate the ultrafast proton dynamics in the first few femtoseconds after X-ray core-level ionization of liquid water. We show through isotope analysis of the Auger spectra that proton-transfer dynamics occur on the same timescale as electron autoionization. Proton transfer leads to the formation of a Zundel-type intermediate [HO*···H···H2O]+, which further ionizes to form a so-far unnoticed type of dicationic charge-separated species with high internal energy. We call the process proton-transfer mediated charge separation.

  5. On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation. (United States)

    Thürmer, Stephan; Ončák, Milan; Ottosson, Niklas; Seidel, Robert; Hergenhahn, Uwe; Bradforth, Stephen E; Slavíček, Petr; Winter, Bernd


    To understand the yield and patterns of damage in aqueous condensed matter, including biological systems, it is essential to identify the initial products subsequent to the interaction of high-energy radiation with liquid water. Until now, the observation of several fast reactions induced by energetic particles in water was not possible on their characteristic timescales. Therefore, some of the reaction intermediates involved, particularly those that require nuclear motion, were not considered when describing radiation chemistry. Here, through a combined experimental and theoretical study, we elucidate the ultrafast proton dynamics in the first few femtoseconds after X-ray core-level ionization of liquid water. We show through isotope analysis of the Auger spectra that proton-transfer dynamics occur on the same timescale as electron autoionization. Proton transfer leads to the formation of a Zundel-type intermediate [HO*···H···H2O](+), which further ionizes to form a so-far unnoticed type of dicationic charge-separated species with high internal energy. We call the process proton-transfer mediated charge separation.

  6. Charge separation dynamics at bulk heterojunctions between poly(3-hexylthiophene) and PbS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Firdaus, Yuliar; Fron, Eduard; Khetubol, Adis; Van der Auweraer, Mark, E-mail: [Laboratory of Photochemistry and Spectroscopy, Division of Molecular Imaging and Photonics, Chemistry Department, KULeuven, Celestijnenlaan 200F, B2404, 3001 Leuven (Belgium); Miranti, Rany; Borchert, Holger; Parisi, Jürgen [Department of Physics, Energy and Semiconductor Research Laboratory, University of Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany); Vandenplas, Erwin; Cheyns, David [Imec vzw, Kapeldreef 75, 3001 Leuven (Belgium)


    Photo-induced electron transfer between poly-(3-hexylthiophene) (P3HT) and small (2.4 nm) PbS quantum dots (QDs), capped by different ligands, was studied by picosecond and femtosecond time-resolved fluorescence and by photo-induced absorption (PIA) measurements. In line with previous experiments, we observed that the efficiency of the quenching of P3HT by PbS QDs increased upon decreasing the average thickness of the ligand shell. This trend was also observed in the PIA spectra and in prior work on the performance of photovoltaic devices where the active layer was a blend of P3HT with PbS QDs capped by different ligands. Combining the pico- and femtosecond fluorescence decays showed that the quenching in blend films of P3HT and PbS QDs treated with 1,4-benzenedithiol occurred over a broad time scale ranging from tens of femtoseconds to hundreds of picoseconds. This complex kinetics was attributed to exciton hopping followed by electron transfer to the conduction band of the QDs. We also compared the wavelength dependence of the internal quantum efficiency (IQE) in the hybrid photovoltaic devices to those devices where the photoactive layer consists of PbS QDs only. Although excitation in the first excitonic transition of the PbS QDs yielded a similar IQE in both devices, the IQE of the hybrid devices tripled at wavelengths where also P3HT started to absorb. This suggests that upon excitation of P3HT in the latter devices, charge generation occurs by photo-induced electron transfer from P3HT to the QDs rather than by energy transfer to the QDs followed by exciton dissociation in the QDs.

  7. Effect of Crystallizable Solvent on Phase Separation and Charge Transport in Polymer-fullerene Films (United States)

    Kaewprajak, A.; Lohawet, K.; Wutikhun, T.; Meemuk, B.; Kumnorkaew, P.; Sagawa, T.


    The effect of 1,3,5-trichlorobenzene (TCB) as crystallizable solvent on poly[N-9‧-heptadecanyl-2,7-carbazole-alt-5,5-(4‧,7‧-di-2-thienyl-2‧,1‧,3‧-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) bulk heterojunction (BHJ) was investigated. We found that phase separation of PCDTBT and PC71BM and formation of the condensed network of polymers were appropriately regulated by addition of TCB in the BHJ films, which were confirmed by optical microscopic, AFM, and TEM observations in addition to current-voltage analyses. Through the formation of a good continuous pathway for carrier transport by the addition of TCB, 2.5 times enhancement of the hole mobility in the BHJ film was attained from 5.82 × 10-5 cm2 V-1 s-1 without TCB to 1.48 × 10-4 cm2 V-1 s-1 with 20 mg ml-1 of TCB.

  8. Charge- and Size-Selective Molecular Separation using Ultrathin Cellulose Membranes

    KAUST Repository

    Puspasari, Tiara


    To date, it is still a challenge to prepare high-flux and highselectivity microporous membranes thinner than 20 nm without introducing defects. In this work, we report for the first time the application of cellulose membranes for selective separation of small molecules. A freestanding cellulose membrane as thin as 10 nm has been prepared through regeneration of trimethylsilyl cellulose (TMSC). The freestanding membrane can be transferred to any desired substrate and shows a normalized flux as high as 700 L m−2 h−1 bar−1 when supported by a porous alumina disc. According to filtration experiments, the membrane exhibits precise size-sieving performances with an estimated pore size between 1.5–3.5 nm depending on the regeneration period and initial TMSC concentration. A perfect discrimination of anionic molecules over neutral species is demonstrated. Moreover, the membrane demonstrates high reproducibility, high scale-up potential, and excellent stability over two months.

  9. Charge Separation in TiO2/BDD Heterojunction Thin Film for Enhanced Photoelectrochemical Performance. (United States)

    Terashima, Chiaki; Hishinuma, Ryota; Roy, Nitish; Sugiyama, Yuki; Latthe, Sanjay S; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Fujishima, Akira


    Semiconductor photocatalysis driven by electron/hole has begun a new era in the field of solar energy conversion and storage. Here we report the fabrication and optimization of TiO2/BDD p-n heterojunction photoelectrode using p-type boron doped diamond (BDD) and n-type TiO2 which shows enhanced photoelectrochemical activity. A p-type BDD was first deposited on Si substrate by microwave plasma chemical vapor deposition (MPCVD) method and then n-type TiO2 was sputter coated on top of BDD grains for different durations. The microstructural studies reveal a uniform disposition of anatase TiO2 and its thickness can be tuned by varying the sputtering time. The formation of p-n heterojunction was confirmed through I-V measurement. A remarkable rectification property of 63773 at 5 V with very small leakage current indicates achieving a superior, uniform and precise p-n junction at TiO2 sputtering time of 90 min. This suitably formed p-n heterojunction electrode is found to show 1.6 fold higher photoelectrochemical activity than bare n-type TiO2 electrode at an applied potential of +1.5 V vs SHE. The enhanced photoelectrochemical performance of this TiO2/BDD electrode is ascribed to the injection of hole from p-type BDD to n-type TiO2, which increases carrier separation and thereby enhances the photoelectrochemical performance.

  10. Improved charge separation efficiency of hematite photoanodes by coating an ultrathin p-type LaFeO3 overlayer (United States)

    Fang, Tao; Guo, Yongsheng; Cai, Songhua; Zhang, Ningsi; Hu, Yingfei; Zhang, Shiying; Li, Zhaosheng; Zou, Zhigang


    Many metal-oxide candidates for photoelectrochemical water splitting exhibit localized small polaron carrier conduction. Especially hematite (α-Fe2O3) photoanodes often suffer from low carrier mobility, which causes the serious bulk electron-hole recombination and greatly limits their PEC performances. In this study, the charge separation efficiency of hematite was enhanced greatly by coating an ultrathin p-type LaFeO3 overlayer. Compared to the hematite photoanodes, the solar water splitting photocurrent of the Fe2O3/LaFeO3 n-p junction exhibits a 90% increase at 1.23 V versus the reversible hydrogen electrode, due to enlarging the band bending and expanding the depletion layer.

  11. Absence of carrier separation in ambipolar charge and spin drift in p{sup +}-GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Cadiz, F.; Paget, D.; Rowe, A. C. H.; Martinelli, L. [Physique de la Matière Condensée, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Arscott, S. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), Université de Lille, CNRS, Avenue Poincaré, Cité Scientifique, 59652 Villeneuve d' Ascq (France)


    The electric field-induced modifications of the spatial distribution of photoelectrons, photoholes, and electronic spins in optically pumped p{sup +} GaAs are investigated using a polarized luminescence imaging microscopy. At low pump intensity, application of an electric field reveals the tail of charge and spin density of drifting electrons. These tails disappear when the pump intensity is increased since a slight differential drift of photoelectrons and photoholes causes the buildup of a strong internal electric field. Spatial separation of photoholes and photoelectrons is very weak so that photoholes drift in the same direction as photoelectrons, thus exhibiting a negative effective mobility. In contrast, for a zero electric field, no significant ambipolar diffusive effects are found in the same sample.

  12. Elucidating the Ultrafast Dynamics of Photoinduced Charge Separation in Metalloporphyrin-Fullerene Dyads Across the Electromagnetic Spectrum

    DEFF Research Database (Denmark)

    Zhang, J.; Pápai, Mátyás Imre; Hirsch, A.


    Metalloporphyrins are prominent building blocks in the synthetic toolbox of advanced photodriven molecular devices. When the central ion is paramagnetic, the relaxation pathways within the manifold of excited states are highly intricate so that unravelling the intramolecular energy and electron...... transfer processes is usually a very complex task. This fact is critically hampering the development of applications based on the enhanced coupling offered by the electronic exchange interaction. In this work, the dynamics of charge separation in a copper porphyrin-fullerene are studied with several......, these results exemplify the potential of multielectron excitation features in transient X-ray spectra as future diagnostics of subfemtosecond electronic dynamics. From a practical point of view, this work is paving the way for elucidating out-of-equilibrium electron transfer events coupled to magnetic...

  13. Charge separation in donor-C60 complexes with real-time Green's functions: The importance of nonlocal correlations. (United States)

    Bostrom, Emil Vinas; Mikkelsen, Anders; Verdozzi, Claudio; Perfetto, Enrico; Stefanucci, Gianluca


    We use the Nonequilibrium Green's Function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time dependent Density Matrix Renormalization Group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical non-local correlation corrections are included. This CS process occurs in ∼10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicate that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.

  14. Light-harvesting complex 1 stabilizes P+QB- charge separation in reaction centers of Rhodobacter sphaeroides. (United States)

    Francia, Francesco; Dezi, Manuela; Rebecchi, Alberto; Mallardi, Antonia; Palazzo, Gerardo; Melandri, Bruno Andrea; Venturoli, Giovanni


    The kinetics of charge recombination following photoexcitation by a laser pulse have been analyzed in the reaction center-light harvesting complex 1 (RC-LH1) purified from the photosynthetic bacterium Rhodobacter sphaeroides. In RC-LH1 core complexes isolated from photosynthetically grown cells P(+)Q(B)(-) recombines with an average rate constant, k approximately 0.3 s(-1), more than three times smaller than that measured in RC deprived of the LH1 (k approximately 1 s(-1)). A comparable, slowed recombination kinetics is observed in RC-LH1 complexes purified from a pufX-deleted strain. Slowing of the charge recombination kinetics is even more pronounced in RC-LH1 complexes isolated from wild-type semiaerobically grown cells (k approximately 0.2 s(-1)). Since the kinetics of P(+)Q(A)(-) recombination is unaffected by the presence of the antenna, the P(+)Q(B)(-) state appears to be energetically stabilized in core complexes. Determinations of the ubiquinone-10 (UQ(10)) complement associated with the purified RC-LH1 complexes always yield UQ(10)/RC ratios larger than 10. These quinone molecules are functionally coupled to the RC-LH1 complex, as judged from the extent of exogenous cytochrome c(2) rapidly oxidized under continuous light excitation. Analysis of P(+)Q(B)(-) recombination, based on a kinetic model which considers fast quinone equilibrium at the Q(B) binding site, indicates that the slowing down of charge recombination kinetics observed in RC-LH1 complexes cannot be explained solely by a quinone concentration effect and suggests that stabilization of the light-induced charge separation is predominantly due to interaction of the Q(B) site with the LH1 complex. The high UQ(10) complements detected in RC-LH1 core complexes, but not in purified light-harvesting complex 2 and in RC, are proposed to reflect an in vivo heterogeneity in the distribution of the quinone pool within the chromatophore bilayer.

  15. Charge separation in branched TiO{sub 2} nanorod array homojunction aroused by quantum effect for enhanced photocatalytic decomposition of gaseous benzene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoxia [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan 430062 (China); Ni, Qian [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Zeng, Dawen, E-mail: [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan 430062 (China); Liao, Guanglan [State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Xie, Changsheng [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China)


    Highlights: • Charge separation in homojunction based on the broadened band gap by quantum effect. • Absolute charge separation by the passivation effect of TiO{sub 2} nanorod. • Long-distance electron transfer behavior in photocatalysis. • Roughed surface for enhanced light harvesting by light trapping effect. - Abstract: As known, the electron transfer behavior in photocatalysis is short-distance transportation, which leads the photo-induced electrons and holes to be localized. The temporarily separated electrons and holes will recombine with each other in the localized region. In this paper, we successfully achieved electron transfer in a homojunction of branched rutile TiO{sub 2} nanorod @nanoparticle core-shell architecture by quantum confinement effect aroused by the nanoparticle, which is proved by the blue-shifting in UV–vis absorption spectrum of the homojunction. Meanwhile, an absolute charge separation is also achieved by the long-distance electron transfer along the single-crystalline rutile TiO{sub 2} nanorod as uninterrupted high-speed electron transfer channel to FTO substrates. Based on the effective charge separation, the photocatalytic decomposition of gaseous benzene by the homojunction is significantly enhanced, yielding 10 times CO{sub 2} than that of the nanorod array. This homojunction interfacial charge separation, aroused by quantum effect, through long-distance transfer along the single-crystalline nanorod gives us inspiration to achieve efficient charge separation with defect-less interfaces, which might can be utilized for real-time environmental abatement and energy generation simultaneously.

  16. Charge separation relative to the reaction plane in Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV. (United States)

    Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agocs, A G; Agostinelli, A; Aguilar Salazar, S; Ahammed, Z; Ahmad, N; Ahmad Masoodi, A; Ahn, S A; Ahn, S U; Akindinov, A; Aleksandrov, D; Alessandro, B; Alfaro Molina, R; Alici, A; Alkin, A; Almaráz Aviña, E; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Anson, C; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Arend, A; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Asryan, A; Augustinus, A; Averbeck, R; Awes, T C; Aystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldini Ferroli, R; Baldisseri, A; Baldit, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Baumann, C; Bearden, I G; Beck, H; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Bergognon, A A E; Berzano, D; Betev, L; Bhasin, A; Bhati, A K; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Bjelogrlic, S; Blanco, F; Blanco, F; Blau, D; Blume, C; Boccioli, M; Bock, N; Böttger, S; Bogdanov, A; Bøggild, H; Bogolyubsky, M; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Bose, S; Bossú, F; Botje, M; Boyer, B; Braidot, E; Braun-Munzinger, P; Bregant, M; Breitner, T; Browning, T A; Broz, M; Brun, R; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Bugaiev, K; Busch, O; Buthelezi, Z; Caballero Orduna, D; Caffarri, D; Cai, X; Caines, H; Calvo Villar, E; Camerini, P; Canoa Roman, V; Cara Romeo, G; Carena, W; Carena, F; Carlin Filho, N; Carminati, F; Casanova Díaz, A; Castillo Castellanos, J; Castillo Hernandez, J F; Casula, E A R; Catanescu, V; Cavicchioli, C; Ceballos Sanchez, C; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chawla, I; Cherney, M; Cheshkov, C; Cheynis, B; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Coccetti, F; Colamaria, F; Colella, D; Conesa Balbastre, G; Conesa Del Valle, Z; Constantin, P; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortese, P; Cortés Maldonado, I; Cosentino, M R; Costa, F; Cotallo, M E; Crescio, E; Crochet, P; Cruz Alaniz, E; Cuautle, E; Cunqueiro, L; Dainese, A; Dalsgaard, H H; Danu, A; Das, D; Das, K; Das, I; Dash, S; Dash, A; De, S; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; Delagrange, H; Deloff, A; Demanov, V; De Marco, N; Dénes, E; De Pasquale, S; Deppman, A; Erasmo, G D; de Rooij, R; Diaz Corchero, M A; Di Bari, D; Dietel, T; Di Giglio, C; Di Liberto, S; Di Mauro, A; Di Nezza, P; Divià, R; Djuvsland, Ø; Dobrin, A; Dobrowolski, T; Domínguez, I; Dönigus, B; Dordic, O; Driga, O; Dubey, A K; Dubla, A; Ducroux, L; Dupieux, P; Dutta Majumdar, M R; Dutta Majumdar, A K; Elia, D; Emschermann, D; Engel, H; Erazmus, B; Erdal, H A; Espagnon, B; Estienne, M; Esumi, S; Evans, D; Eyyubova, G; Fabris, D; Faivre, J; Falchieri, D; Fantoni, A; Fasel, M; Fearick, R; Fedunov, A; Fehlker, D; Feldkamp, L; Felea, D; Fenton-Olsen, B; Feofilov, G; Fernández Téllez, A; Ferretti, A; Ferretti, R; Festanti, A; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Francescon, A; Frankenfeld, U; Fuchs, U; Furget, C; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A; Gallio, M; Gangadharan, D R; Ganoti, P; Garabatos, C; Garcia-Solis, E; Garishvili, I; Gerhard, J; Germain, M; Geuna, C; Gheata, A; Gheata, M; Ghidini, B; Ghosh, P; Gianotti, P; Girard, M R; Giubellino, P; Gladysz-Dziadus, E; Glässel, P; Gomez, R; Ferreiro, E G; González-Trueba, L H; González-Zamora, P; Gorbunov, S; Goswami, A; Gotovac, S; Grabski, V; Graczykowski, L K; Grajcarek, R; Grelli, A; Grigoras, A; Grigoras, C; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grinyov, B; Grion, N; Gros, P; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerra Gutierrez, C; Guerzoni, B; Guilbaud, M; Gulbrandsen, K; Gunji, T; Gupta, A; Gupta, R; Gutbrod, H; Haaland, Ø; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Han, B H; Hanratty, L D; Hansen, A; Harmanova, Z; Harris, J W; Hartig, M; Hasegan, D; Hatzifotiadou, D; Hayrapetyan, A; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, N; Hess, B A; Hetland, K F; Hicks, B; Hille, P T; Hippolyte, B; Horaguchi, T; Hori, Y; Hristov, P; Hřivnáčová, I; Huang, M; Humanic, T J; Hwang, D S; Ichou, R; Ilkaev, R; Ilkiv, I; Inaba, M; Incani, E; Innocenti, G M; Innocenti, P G; Ippolitov, M; Irfan, M; Ivan, C; Ivanov, M; Ivanov, A; Ivanov, V; Ivanytskyi, O; Jacobs, P M; Jang, H J; Janik, R; Janik, M A; Jayarathna, P H S Y; Jena, S; Jha, D M; Jimenez Bustamante, R T; Jirden, L; Jones, P G; Jung, H; Jusko, A; Kaidalov, A B; Kakoyan, V; Kalcher, S; Kaliňák, P; Kalliokoski, T; Kalweit, A; Kang, J H; Kaplin, V; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karpechev, E; Kazantsev, A; Kebschull, U; Keidel, R; Khan, M M; Khan, P; Khan, S A; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, J S; Kim, D J; Kim, D W; Kim, J H; Kim, T; Kim, M; Kim, M; Kim, S H; Kim, B; Kim, S; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Klay, J L; Klein, J; Klein-Bösing, C; Kliemant, M; Kluge, A; Knichel, M L; Knospe, A G; Koch, K; Köhler, M K; Kollegger, T; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Konevskikh, A; Korneev, A; Kour, R; Kowalski, M; Kox, S; Koyithatta Meethaleveedu, G; Kral, J; Králik, I; Kramer, F; Kraus, I; Krawutschke, T; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Krus, M; Kryshen, E; Krzewicki, M; Kucheriaev, Y; Kugathasan, T; Kuhn, C; Kuijer, P G; Kulakov, I; Kumar, J; Kurashvili, P; Kurepin, A; Kurepin, A B; Kuryakin, A; Kushpil, S; Kushpil, V; Kvaerno, H; Kweon, M J; Kwon, Y; Ladrón de Guevara, P; Lakomov, I; Langoy, R; La Pointe, S L; Lara, C; Lardeux, A; La Rocca, P; Lazzeroni, C; Lea, R; Le Bornec, Y; Lechman, M; Lee, S C; Lee, K S; Lee, G R; Lefèvre, F; Lehnert, J; Leistam, L; Lenti, V; León, H; Leoncino, M; León Monzón, I; León Vargas, H; Lévai, P; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Liu, L; Loggins, V R; Loginov, V; Lohn, S; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luquin, L; Luzzi, C; Ma, R; Ma, K; Madagodahettige-Don, D M; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Malaev, M; Maldonado Cervantes, I; Malinina, L; Mal'kevich, D; Malzacher, P; Mamonov, A; Manceau, L; Mangotra, L; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; Marin Tobon, C A; Markert, C; Martashvili, I; Martinengo, P; Martínez, M I; Martínez Davalos, A; Martínez García, G; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Massacrier, L; Mastroserio, A; Matthews, Z L; Matyja, A; Mayer, C; Mazer, J; Mazzoni, M A; Meddi, F; Menchaca-Rocha, A; Mercado Pérez, J; Meres, M; Miake, Y; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Miśkowiec, D; Mitu, C; Mlynarz, J; Mohanty, B; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Musa, L; Musso, A; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Naumov, N P; Navin, S; Nayak, T K; Nazarenko, S; Nazarov, G; Nedosekin, A; Nicassio, M; Niculescu, M; Nielsen, B S; Niida, T; Nikolaev, S; Nikolic, V; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Novitzky, N; Nyanin, A; Nyatha, A; Nygaard, C; Nystrand, J; Ochirov, A; Oeschler, H; Oh, S; Oh, S K; Oleniacz, J; Oppedisano, C; Ortiz Velasquez, A; Ortona, G; Oskarsson, A; Ostrowski, P; Otwinowski, J; Oyama, K; Ozawa, K; Pachmayer, Y; Pachr, M; Padilla, F; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Pastirčák, B; Patalakha, D I; Paticchio, V; Pavlinov, A; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perez Lezama, E; Perini, D; Perrino, D; Peryt, W; Pesci, A; Peskov, V; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Piccotti, A; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piyarathna, D B; Płoskoń, M; Pluta, J; Pocheptsov, T; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polák, K; Polichtchouk, B; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puchagin, S; Puddu, G; Pulvirenti, A; Punin, V; Putiš, M; 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Schreiner, S; Schuchmann, S; Schukraft, J; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, P A; Scott, R; Segato, G; Selyuzhenkov, I; Senyukov, S; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, S; Sharma, N; Rohni, S; Shigaki, K; Shimomura, M; Shtejer, K; Sibiriak, Y; Siciliano, M; Sicking, E; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Singhal, V; Sinha, T; Sinha, B C; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Son, H; Song, J; Song, M; Soos, C; Soramel, F; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stan, I; Stefanek, G; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strabykin, K; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Sukhorukov, M; Sultanov, R; Sumbera, M; Susa, T; Szanto de Toledo, A; Szarka, I; Szczepankiewicz, A; Szostak, A; Szymański, M; Takahashi, J; Tapia Takaki, J D; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Thäder, J; Thomas, D; Thomas, J H; Tieulent, R; Timmins, A R; Tlusty, D; Toia, A; Torii, H; Toscano, L; Truesdale, D; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urbán, J; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vallero, S; van der Kolk, N; Vande Vyvre, P; van Leeuwen, M; Vannucci, L; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Vikhlyantsev, O; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, Y; Vinogradov, L; Virgili, T; Viyogi, Y P; Vodopyanov, A; Voloshin, K; Voloshin, S; Volpe, G; von Haller, B; Vranic, D; Ovrebekk, G; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, V; Wagner, B; Wan, R; Wang, Y; Wang, D; Wang, Y; Wang, M; Watanabe, K; Weber, M; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, G; Wilk, A; Williams, M C S; Windelband, B; Xaplanteris Karampatsos, L; Yaldo, C G; Yamaguchi, Y; Yang, H; Yang, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yoon, J; Yu, W; Yuan, X; Yushmanov, I; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, H; Zhang, X; Zhou, Y; Zhou, D; Zhou, F; Zhu, J; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M; Zyzak, M


    Measurements of charge-dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sqrt[s(NN)] = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudorapidity range |η| < 0.8 are presented as a function of the collision centrality, particle separation in pseudorapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge-dependent azimuthal correlations observed at RHIC and LHC energies.

  17. Separation of Flip and Non-Flip parst of Charge Exchange np->pn at energies Tn = 0.5 - 2.0 GeV

    CERN Document Server

    Shindin, R A; Chernykh, E V; Guriev, D K; Nomofilov, A A; Prytkov, V Yu; Sharov, V I; Strunov, L I


    The new Delta-Sigma experimental data on the ratio $R_{dp}$ allowed separating the Flip and Non-Flip parts of the differential cross section of $np\\to pn$ charge exchange process at the zero angle by the Dean formula. The PSA solutions for the $np\\to np$ elastic scattering are transformed to the $np\\to pn$ charge exchange representation using unitary transition, and good agreement is obtain.

  18. Lead induced changes in phosphorylation of PSII proteins in low light grown pea plants. (United States)

    Wioleta, Wasilewska; Anna, Drożak; Ilona, Bacławska; Kamila, Kąkol; Elżbieta, Romanowska


    Light-intensity and redox-state induced thylakoid proteins phosphorylation involved in structural changes and in regulation of protein turnover. The presence of heavy metal ions triggers a wide range of cellular responses including changes in plant growth and photosynthesis. Plants have evolved a number of mechanisms to protect photosynthetic apparatus. We have characterized the effect of lead on PSII protein phosphorylation in pea (Pisum sativum L.) plants grown in low light conditions. Pb ions affected only slightly photochemical efficiency of PSII and had no effect on organization of thylakoid complexes. Lead activated strongly phosphorylation of PSII core D1 protein and dephosphorylation of this protein did not proceed in far red light. D1 protein was also not degraded in this conditions. However, phosphorylation of LHCII proteins was not affected by lead. These results indicate that Pb(2+) stimulate the phosphorylation of PSII core proteins and by disturbing the disassembly of supercomplexes play a role in PSII repair mechanism. LHCII phosphorylation could control the distribution of energy between the photosystems in low light conditions. This demonstrates that plants may respond to heavy metals by induction different pathways responsible for protein protection under stress conditions.

  19. Chloroplast movement provides photoprotection to plants by redistributing PSII damage within leaves. (United States)

    Davis, Phillip A; Hangarter, Roger P


    Plants use light to fix carbon through the process of photosynthesis but light also causes photoinhibition, by damaging photosystem II (PSII). Plants can usually adjust their rate of PSII repair to equal the rate of damage, but under stress conditions or supersaturating light-intensities damage may exceed the rate of repair. Light-induced chloroplast movements are one of the many mechanisms plants have evolved to minimize photoinhibition. We found that chloroplast movements achieve a measure of photoprotection to PSII by altering the distribution of photoinhibition through depth in leaves. When chloroplasts are in the low-light accumulation arrangement a greater proportion of PSII damage occurs near the illuminated surface than for leaves where the chloroplasts are in the high-light avoidance arrangement. According to our findings chloroplast movements can increase the overall efficiency of leaf photosynthesis in at least two ways. The movements alter light profiles within leaves to maximize photosynthetic output and at the same time redistribute PSII damage throughout the leaf to reduce the amount of inhibition received by individual chloroplasts and prevent a decrease in photosynthetic potential.

  20. Time-resolved photoluminescence measurements for determining voltage-dependent charge-separation efficiencies of subcells in triple-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tex, David M.; Ihara, Toshiyuki; Kanemitsu, Yoshihiko, E-mail: [Institute for Chemical Research and JST-CREST, Kyoto University, Uji, Kyoto 611-0011 (Japan); Akiyama, Hidefumi [Institute for Solid State Physics and JST-CREST, The University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Imaizumi, Mitsuru [Japan Aerospace Exploration Agency, Tsukuba, Ibaraki 305-8505 (Japan)


    Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible.

  1. Enhanced Charge Separation and FRET at Heterojunctions between Semiconductor Nanoparticles and Conducting Polymer Nanofibers for Efficient Solar Light Harvesting. (United States)

    Sardar, Samim; Kar, Prasenjit; Remita, Hynd; Liu, Bo; Lemmens, Peter; Kumar Pal, Samir; Ghosh, Srabanti


    Energy harvesting from solar light employing nanostructured materials offer an economic way to resolve energy and environmental issues. We have developed an efficient light harvesting heterostructure based on poly(diphenylbutadiyne) (PDPB) nanofibers and ZnO nanoparticles (NPs) via a solution phase synthetic route. ZnO NPs (~20 nm) were homogeneously loaded onto the PDPB nanofibers as evident from several analytical and spectroscopic techniques. The photoinduced electron transfer from PDPB nanofibers to ZnO NPs has been confirmed by steady state and picosecond-resolved photoluminescence studies. The co-sensitization for multiple photon harvesting (with different energies) at the heterojunction has been achieved via a systematic extension of conjugation from monomeric to polymeric diphenyl butadiyne moiety in the proximity of the ZnO NPs. On the other hand, energy transfer from the surface defects of ZnO NPs (~5 nm) to PDPB nanofibers through Förster Resonance Energy Transfer (FRET) confirms the close proximity with molecular resolution. The manifestation of efficient charge separation has been realized with ~5 fold increase in photocatalytic degradation of organic pollutants in comparison to polymer nanofibers counterpart under visible light irradiation. Our results provide a novel approach for the development of nanoheterojunctions for efficient light harvesting which will be helpful in designing future solar devices.

  2. Transient and modulated charge separation at CuInSe2/C60 and CuInSe2/ZnPc hybrid interfaces (United States)

    von Morzé, Natascha; Dittrich, Thomas; Calvet, Wolfram; Lauermann, Iver; Rusu, Marin


    Spectral dependent charge transfer and exciton dissociation have been investigated at hybrid interfaces between inorganic polycrystalline CuInSe2 (untreated and Na-conditioned) thin films and organic C60 as well as zinc phthalocyanine (ZnPc) layers by transient and modulated surface photovoltage measurements. The stoichiometry and electronic properties of the bare CuInSe2 surface were characterized by photoelectron spectroscopy which revealed a Cu-poor phase with n-type features. After the deposition of the C60 layer, a strong band bending at the CuInSe2 surface was observed. Evidence for dissociation of excitons followed by charge separation was found at the CuInSe2/ZnPc interface. The Cu-poor layer at the CuInSe2 surface was found to be crucial for transient and modulated charge separation at CuInSe2/organic hybrid interfaces.

  3. Charge separation relative to the reaction plane in Pb-Pb collisions at $\\sqrt{s_{NN}}$= 2.76 TeV

    CERN Document Server

    Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergognon, Anais Annick Erica; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Bock, Nicolas; Boettger, Stefan; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Boyer, Bruno Alexandre; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Bugaiev, Kyrylo; Busch, Oliver; Buthelezi, Edith Zinhle; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Sukalyan; Chattopadhyay, Subhasis; Chawla, Isha; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Colella, Domenico; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; D'Erasmo, Ginevra; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Kushal; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; de Rooij, Raoul Stefan; Delagrange, Hugues; Deloff, Andrzej; Demanov, Vyacheslav; Denes, Ervin; Deppman, Airton; Di Bari, Domenico; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erazmus, Barbara; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Fenton-Olsen, Bo; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Alessandro; Ferretti, Roberta; Festanti, Andrea; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Andrey; Ivanov, Marian; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacobs, Peter; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jha, Deeptanshu Manu; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jusko, Anton; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Mohisin Mohammed; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Dong Jo; Kim, Do Won; Kim, Jonghyun; Kim, Jin Sook; Kim, Minwoo; Kim, Mimae; Kim, Se Yong; Kim, Seon Hee; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Koch, Kathrin; Kohler, Markus; Kollegger, Thorsten; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kugathasan, Thanushan; Kuhn, Christian Claude; Kuijer, Paul; Kulakov, Igor; Kumar, Jitendra; Kurashvili, Podist; Kurepin, A; Kurepin, AB; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasily; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; Lazzeroni, Cristina; Le Bornec, Yves; Lea, Ramona; Lechman, Mateusz; Lee, Graham Richard; Lee, Ki Sang; Lee, Sung Chul; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lemmon, Roy Crawford; Lenti, Vito; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Leoncino, Marco; Levai, Peter; Lien, Jorgen; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Rongrong; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Mal'Kevich, Dmitry; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Marin Tobon, Cesar Augusto; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Niculescu, Mihai; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Oleniacz, Janusz; Oppedisano, Chiara; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, Susanta Kumar; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodrigues Fernandes Rabacal, Bartolomeu; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Sano, Satoshi; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selyuzhenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szostak, Artur Krzysztof; Szymanski, Maciej; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tarazona Martinez, Alfonso; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Toia, Alberica; Torii, Hisayuki; Tosello, Flavio; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; van Leeuwen, Marco; Vande Vyvre, Pierre; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; Øvrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Weber, Michael; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Alexander; Wilk, Grzegorz Andrzej; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo; Zyzak, Maksym


    Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\\eta | < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with the expectation of a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. Models incorporating effects of local parity violation in strong interactions fail to describe the observed collision energy dependence.

  4. Near-Infrared Photoelectrochemical Conversion via Photoinduced Charge Separation in Supramolecular Complexes of Anionic Phthalocyanines with Li(+)@C60. (United States)

    Kawashima, Yuki; Ohkubo, Kei; Blas-Ferrando, Vicente Manuel; Sakai, Hayato; Font-Sanchis, Enrique; Ortíz, Javier; Fernández-Lázaro, Fernando; Hasobe, Taku; Sastre-Santos, Ángela; Fukuzumi, Shunichi


    Two phthalocyanines possessing carboxylate groups ((TBA)4H2Pc·1 and (TBA)4H2Pc·2) form 1:2 supramolecular complexes with lithium cation-encapsulated C60 (Li(+)@C60) [H2Pc·1(4-)/(Li(+)@C60)2 and H2Pc·2(4-)/(Li(+)@C60)2] in a polar mixed solvent. From the UV-vis spectral changes, the binding constants (K) were estimated as ca. 10(12) M(-2). Upon the photoexcitation of constructed supramolecular complexes, photoinduced electron transfer occurred to form the charge-separated (CS) state. The lifetime of the CS state was determined to be 1.2 ms for H2Pc·2(4-)/(Li(+)@C60)2, which is the longest CS lifetime among the porphyrinoid/fullerene supramolecular complexes. H2Pc·1(4-)/(Li(+)@C60)2 also afforded the long-lived CS state of 1.0 ms. The spin state of the long-lived CS states was determined to be a triplet, as indicated by the EPR signal at g = 4. The reorganization energy (λ) and the electronic coupling term were determined to be λ = 1.70 eV, V = 0.15 cm(-1) from the temperature dependence of the rate constant for the charge recombination of the CS state of H2Pc·1(4-)/(Li(+)@C60)2. The energy of the CS state (0.49 eV) is much smaller than the reorganization energy, indicating that the back-electron-transfer process is located in the Marcus normal region. The small electronic coupling term results from the spin-forbidden back electron transfer due to the triplet CS state. Supramolecular complexes of anionic zinc phthalocyanines with Li(+)@C60 were also prepared and investigated. The ZnPc·4(4-)/Li(+)@C60 supramolecular nanoclusters were assembled on the optically transparent electrode (OTE) of nanostructured SnO2 (OTE/SnO2) to construct the dye-sensitized solar cell. The IPCE (incident photon-to-photocurrent efficiency) values of OTE/SnO2/(ZnPc·4(4-)/Li(+)@C60)n were much higher than the sum of the two IPCE values of the individual systems OTE/SnO2/(Li(+)@C60)n and OTE/SnO2/(ZnPc·4(4-))n, covering the near-infrared region.

  5. Oxyradicals and PSII activity in maize leaves in the absence of UV ...

    Indian Academy of Sciences (India)

    ... oxyradicals invoked higher activity of antioxidant enzymes like superoxide dismutase and peroxidase under ambient UV, they also imposed limitation on the photosynthetic efficiency of PSII. Exclusion of UV components (UV-B 280–315 nm; UV-A 315–400 nm) translated to enhanced photosynthesis, growth and biomass.

  6. Long-Lived Photoinduced Charge Separation in a Trinuclear Iron-μ 3 -oxo-based Metal–Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, Lauren [Department; Kucheryavy, Pavel [Department; Liu, Cunming [X-ray; Zhang, Xiaoyi [X-ray; Lockard, Jenny V. [Department


    The presence of long-lived charge-separated excited states in metal-organic frameworks (MOFs) can enhance their photocatalytic activity by decreasing the probability that photogenerated electrons and holes recombine before accessing adsorbed reactants. Detecting these charge separated states via optical transient absorption, however, can be challenging when they lack definitive optical signatures. Here, we investigate the long-lived excited state of a MOF with such vague optical properties, MIL-100(Fe), comprised of Fe3-μ3-oxo clusters and trimesic acid linkers using Fe K-edge X-ray transient absorption (XTA) spectroscopy, to unambiguously determine its ligand-to-metal charge transfer character. Spectra measured at time delays up to 3.6 μs confirm the long lived nature of the charge separated excited state. Several trinuclear iron μ3- oxo carboxylate complexes, which model the trinuclear cores of the MOF structure, are measured for comparison using both steady state XAS and XTA to further support this assignment and corresponding decay time. The MOF is prepared as a colloidal nanoparticle suspension for these measurements so both its fabrication and particle size analysis are presented, as well.

  7. In vivo assessment of effect of phytotoxin tenuazonic acid on PSII reaction centers. (United States)

    Chen, Shiguo; Strasser, Reto Jörg; Qiang, Sheng


    Tenuazonic acid (TeA), a phytotoxin produced by the fungus Alternaria alternata isolated from diseased croftonweed (Ageratina adenophora), exhibits a strong inhibition in photosystem II (PSII) activity. In vivo chlorophyll fluorescence transients of the host plant croftonweed, show that the dominant effect of TeA is not on the primary photochemical reaction but on the biochemical reaction after QA. The most important action site of TeA is the QB site on the PSII electron-acceptor side, blocking electron transport beyond QA(-) by occupying the QB site in the D1 protein. However, TeA does not affect the antenna pigments, the energy transfer from antenna pigment molecules to reaction centers (RCs), and the oxygen-evolving complex (OEC) at the donor side of PSII. TeA severely inactivated PSII RCs. The fraction of non-QA reducing centers and non-QB reducing centers show a time- and concentration-dependent linear increase. Conversely, the amount of active QA or QB reducing centers declined sharply in a linear way. The fraction of non-QB reducing centers calculated from data of fluorescence transients is close to the number of PSII RCs with their QB site filled by TeA. An increase of the step-J level (VJ) in the OJIP fluorescence transients attributed to QA(-) accumulation due to TeA bound to the QB site is a typical characteristic response of the plants leaf with respect to TeA penetration. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  8. Final Technical Report for the Energy Frontier Research Center Understanding Charge Separation and Transfer at Interfaces in Energy Materials (EFRC:CST)

    Energy Technology Data Exchange (ETDEWEB)

    Vanden Bout, David A. [Univ. of Texas, Austin, TX (United States)


    Our EFRC was founded with the vision of creating a broadly collaborative and synergistic program that would lead to major breakthroughs in the molecular-level understanding of the critical interfacial charge separation and charge transfer (CST) processes that underpin the function of candidate materials for organic photovoltaic (OPV) and electrical-energy-storage (EES) applications. Research in these energy contexts shares an imposing challenge: How can we understand charge separation and transfer mechanisms in the presence of immense materials complexity that spans multiple length scales? To address this challenge, our 50-member Center undertook a total of 28 coordinated research projects aimed at unraveling the CST mechanisms that occur at interfaces in these nanostructured materials. This rigorous multi-year study of CST interfaces has greatly illuminated our understanding of early-timescale processes (e.g., exciton generation and dissociation dynamics at OPV heterojunctions; control of Li+-ion charging kinetics by surface chemistry) occurring in the immediate vicinity of interfaces. Program outcomes included: training of 72 graduate student and postdoctoral energy researchers at 5 institutions and spanning 7 academic disciplines in science and engineering; publication of 94 peer-reviewed journal articles; and dissemination of research outcomes via 340 conference, poster and other presentations. Major scientific outcomes included: implementation of a hierarchical strategy for understanding the electronic communication mechanisms and ultimate fate of charge carriers in bulk heterojunction OPV materials; systematic investigation of ion-coupled electron transfer processes in model Li-ion battery electrode/electrolyte systems; and the development and implementation of 14 unique technologies and instrumentation capabilities to aid in probing sub-ensemble charge separation and transfer mechanisms.

  9. Transient and modulated charge separation at CuInSe{sub 2}/C{sub 60} and CuInSe{sub 2}/ZnPc hybrid interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Morzé, Natascha von, E-mail:; Dittrich, Thomas, E-mail:; Calvet, Wolfram, E-mail:; Lauermann, Iver, E-mail:; Rusu, Marin, E-mail:


    Highlights: • Surface physical properties of non- and Na-treated CuInSe{sub 2} layers studied. • Evidence of exciton dissociation and charge separation at CuInSe{sub 2}/ZnPc interface. • Strong band bending at the CuInSe{sub 2} surface in contact with C{sub 60} observed. • No evidence for exciton dissociation at the CuInSe{sub 2}/C{sub 60} interface found. • Cu-poor phase at CuInSe{sub 2}/organic interface crucial for charge separation. - Abstract: Spectral dependent charge transfer and exciton dissociation have been investigated at hybrid interfaces between inorganic polycrystalline CuInSe{sub 2} (untreated and Na-conditioned) thin films and organic C{sub 60} as well as zinc phthalocyanine (ZnPc) layers by transient and modulated surface photovoltage measurements. The stoichiometry and electronic properties of the bare CuInSe{sub 2} surface were characterized by photoelectron spectroscopy which revealed a Cu-poor phase with n-type features. After the deposition of the C{sub 60} layer, a strong band bending at the CuInSe{sub 2} surface was observed. Evidence for dissociation of excitons followed by charge separation was found at the CuInSe{sub 2}/ZnPc interface. The Cu-poor layer at the CuInSe{sub 2} surface was found to be crucial for transient and modulated charge separation at CuInSe{sub 2}/organic hybrid interfaces.

  10. Co(II)–grafted Ag{sub 3}PO{sub 4} photocatalysts with unexpected photocatalytic ability: Enhanced photogenerated charge separation efficiency, photocatalytic mechanism and activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuna [College of Textile Engineering, Zhejiang Industry Polytechnic College, Shaoxing 312000 (China); Zhang, Shujuan, E-mail: [College of Science, Tianjin University of Science & Technology, Tianjin 300457 (China); Song, Limin, E-mail: [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China)


    Highlights: • Co–Ag{sub 3}PO{sub 4} with higher photodegradation ability was synthesized. • ·OH was the main active species in the oxidation of MO. • The synergy of Co(II) and Ag{sub 3}PO{sub 4} greatly enhanced the separation efficiency. - Abstract: Since the photocatalytic capability is determined by the separation and transmission efficiency of photoinduced charges, its improvement remains a challenge for development of efficient photocatalysts. Here, we made large improvement on the surface of Ag{sub 3}PO{sub 4} using Co(II)–grafted Ag{sub 3}PO{sub 4} by a hydrothermal method. During the photocatalytic process, Co(II) was oxidized to Co(III) by the photogenerated holes under visible light radiation, which enhanced the separation efficiency of photogenerated charges. Meanwhile, the Co(III) as-formed could oxidize dye molecules, which recovered the Co(II). The synergy of Co(II) and Ag{sub 3}PO{sub 4} greatly promoted the separation and transmission efficiency of the photogenerated charges, and severely improved the photocatalytic activity of Ag{sub 3}PO{sub 4}. The surface grafted Co(II) on Ag{sub 3}PO{sub 4} is responsible for the enhancement of photocatalytic activity.

  11. Overexpressed Superoxide Dismutase and Catalase Act Synergistically to Protect the Repair of PSII during Photoinhibition in Synechococcus elongatus PCC 7942. (United States)

    Sae-Tang, Penporn; Hihara, Yukako; Yumoto, Isao; Orikasa, Yoshitake; Okuyama, Hidetoshi; Nishiyama, Yoshitaka


    The repair of PSII under strong light is particularly sensitive to reactive oxygen species (ROS), such as the superoxide radical and hydrogen peroxide, and these ROS are efficiently scavenged by superoxide dismutase (SOD) and catalase. In the present study, we generated transformants of the cyanobacterium Synechococcus elongatus PCC 7942 that overexpressed an iron superoxide dismutase (Fe-SOD) from Synechocystis sp. PCC 6803; a highly active catalase (VktA) from Vibrio rumoiensis; and both enzymes together. Then we examined the sensitivity of PSII to photoinhibition in the three strains. In cells that overexpressed either Fe-SOD or VktA, PSII was more tolerant to strong light than it was in wild-type cells. Moreover, in cells that overexpressed both Fe-SOD and VktA, PSII was even more tolerant to strong light. However, the rate of photodamage to PSII, as monitored in the presence of chloramphenicol, was similar in all three transformant strains and in wild-type cells, suggesting that the overexpression of these ROS-scavenging enzymes might not protect PSII from photodamage but might protect the repair of PSII. Under strong light, intracellular levels of ROS fell significantly, and the synthesis de novo of proteins that are required for the repair of PSII, such as the D1 protein, was enhanced. Our observations suggest that overexpressed Fe-SOD and VktA might act synergistically to alleviate the photoinhibition of PSII by reducing intracellular levels of ROS, with resultant protection of the repair of PSII from oxidative inhibition. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email:

  12. High-potential perfluorinated phthalocyanine-fullerene dyads for generation of high-energy charge-separated states: formation and photoinduced electron-transfer studies. (United States)

    Das, Sushanta K; Mahler, Andrew; Wilson, Angela K; D'Souza, Francis


    High oxidation potential perfluorinated zinc phthalocyanines (ZnF(n)Pcs) are synthesised and their spectroscopic, redox, and light-induced electron-transfer properties investigated systematically by forming donor-acceptor dyads through metal-ligand axial coordination of fullerene (C60) derivatives. Absorption and fluorescence spectral studies reveal efficient binding of the pyridine- (Py) and phenylimidazole-functionalised fullerene (C60Im) derivatives to the zinc centre of the F(n)Pcs. The determined binding constants, K, in o-dichlorobenzene for the 1:1 complexes are in the order of 10(4) to 10(5) M(-1); nearly an order of magnitude higher than that observed for the dyad formed from zinc phthalocyanine (ZnPc) lacking fluorine substituents. The geometry and electronic structure of the dyads are determined by using the B3LYP/6-31G* method. The HOMO and LUMO levels are located on the Pc and C60 entities, respectively; this suggests the formation of ZnF(n)Pc(.+)-C60Im(.-) and ZnF(n)Pc(.+)-C60Py(.-) (n=0, 8 or 16) intra-supramolecular charge-separated states during electron transfer. Electrochemical studies on the ZnPc-C60 dyads enable accurate determination of their oxidation and reduction potentials and the energy of the charge-separated states. The energy of the charge-separated state for dyads composed of ZnF(n)Pc is higher than that of normal ZnPc-C60 dyads and reveals their significance in harvesting higher amounts of light energy. Evidence for charge separation in the dyads is secured from femtosecond transient absorption studies in nonpolar toluene. Kinetic evaluation of the cation and anion radical ion peaks reveals ultrafast charge separation and charge recombination in dyads composed of perfluorinated phthalocyanine and fullerene; this implies their significance in solar-energy harvesting and optoelectronic device building applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effect of different photoanode nanostructures on the initial charge separation and electron injection process in dye sensitized solar cells: A photophysical study with indoline dyes

    Energy Technology Data Exchange (ETDEWEB)

    Idígoras, Jesús [Nanostructured Solar Cells Group, Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera, km 1, ES-41013 Seville (Spain); Sobuś, Jan [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań (Poland); Jancelewicz, Mariusz [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Azaceta, Eneko; Tena-Zaera, Ramon [Materials Division, IK4-CIDETEC, Parque Tecnológico de San Sebastián, Paseo Miramón 196, Donostia-San Sebastián, 20009 (Spain); Anta, Juan A. [Nanostructured Solar Cells Group, Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera, km 1, ES-41013 Seville (Spain); Ziółek, Marcin, E-mail: [Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań (Poland)


    Ultrafast and fast charge separation processes were investigated for complete cells based on several ZnO-based photoanode nanostructures and standard TiO{sub 2} nanoparticle layers sensitized with the indoline dye coded D358. Different ZnO morphologies (nanoparticles, nanowires, mesoporous), synthesis methods (hydrothermal, gas-phase, electrodeposition in aqueous media and ionic liquid media) and coatings (ZnO–ZnO core–shell, ZnO–TiO{sub 2} core–shell) were measured by transient absorption techniques in the time scale from 100 fs to 100 μs and in the visible and near-infrared spectral range. All of ZnO cells show worse electron injection yields with respect to those with standard TiO{sub 2} material. Lower refractive index of ZnO than that of TiO{sub 2} is suggested to be an additional factor, not considered so far, that can decrease the performance of ZnO-based solar cells. Evidence of the participation of the excited charge transfer state of the dye in the charge separation process is provided here. The lifetime of this state in fully working devices extends from several ps to several tens of ps, which is much longer than the typically postulated electron injection times in all-organic dye-sensitized solar cells. The results here provided, comprising a wide variety of morphologies and preparation methods, point to the universality of the poor performance of ZnO as photoanode material with respect to standard TiO{sub 2}. - Highlights: • Wide variety of morphologies and preparation methods has been checked for ZnO cells. • All ZnO cells work worse than TiO{sub 2} ones. • Effective refractive index might be an additional factor in solar cell performance. • Excited charge transfer state of indoline dyes participates in the charge separation.

  14. Pore space partition and charge separation in cage-within-cage indium-organic frameworks with high CO2 uptake. (United States)

    Zheng, Shou-Tian; Bu, Julia T; Li, Yufei; Wu, Tao; Zuo, Fan; Feng, Pingyun; Bu, Xianhui


    The integration of negatively charged single-metal building blocks {In(CO2)4} and positively charged trimeric clusters {In3O} leads to three unique cage-within-cage-based porous materials, which exhibit not only high hydrothermal, thermal, and photochemical stability but also attractive structural features contributing to a very high CO2 uptake capacity of up to 119.8 L/L at 273 K and 1 atm.

  15. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: Exploring range-separation tuning (United States)

    de Queiroz, Thiago B.; Kümmel, Stephan


    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an "optimally tuned" range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  16. Interfacial charge separation and recombination in InP and quasi-type II InP/CdS core/shell quantum dot-molecular acceptor complexes. (United States)

    Wu, Kaifeng; Song, Nianhui; Liu, Zheng; Zhu, Haiming; Rodríguez-Córdoba, William; Lian, Tianquan


    Recent studies of group II-VI colloidal semiconductor heterostuctures, such as CdSe/CdS core/shell quantum dots (QDs) or dot-in-rod nanorods, show that type II and quasi-type II band alignment can facilitate electron transfer and slow down charge recombination in QD-molecular electron acceptor complexes. To explore the general applicability of this wave function engineering approach for controlling charge transfer properties, we investigate exciton relaxation and dissociation dynamics in InP (a group III-V semiconductor) and InP/CdS core/shell (a heterostructure beween group III-V and II-VI semiconductors) QDs by transient absorption spectroscopy. We show that InP/CdS QDs exhibit a quasi-type II band alignment with the 1S electron delocalized throughout the core and shell and the 1S hole confined in the InP core. In InP-methylviologen (MV(2+)) complexes, excitons in the QD can be dissociated by ultrafast electron transfer to MV(2+) from the 1S electron level (with an average time constant of 11.4 ps) as well as 1P and higher electron levels (with a time constant of 0.39 ps), which is followed by charge recombination to regenerate the complex in its ground state (with an average time constant of 47.1 ns). In comparison, InP/CdS-MV(2+) complexes show similar ultrafast charge separation and 5-fold slower charge recombination rates, consistent with the quasi-type II band alignment in these heterostructures. This result demonstrates that wave function engineering in nanoheterostructures of group III-V and II-VI semiconductors provides a promising approach for optimizing their light harvesting and charge separation for solar energy conversion applications.

  17. Enhanced Internal Quantum Efficiency in Dye-Sensitized Solar Cells: Effect of Long-Lived Charge-Separated State of Sensitizers. (United States)

    Sun, Haiya; Liu, Dongzhi; Wang, Tianyang; Lu, Ting; Li, Wei; Ren, Siyao; Hu, Wenping; Wang, Lichang; Zhou, Xueqin


    Effective charge separation is one of the key determinants for the photovoltaic performance of the dye-sensitized solar cells (DSSCs). Herein, two charge-separated (CS) sensitizers, MTPA-Pyc and YD-Pyc, have been synthesized and applied in DSSCs to investigate the effect of the CS states of the sensitizers on the device's efficiency. The CS states with lifetimes of 64 and 177 ns for MTPA-Pyc and YD-Pyc, respectively, are formed via the photoinduced electron transfer (PET) from the 4-styryltriphenylamine (MTPA) or 4-styrylindoline (YD) donor to the pyrimidine cyanoacrylic acid (Pyc) acceptor. DSSCs based on MTPA-Pyc and YD-Pyc exhibit high internal quantum efficiency (IQE) values of over 80% from 400 to 600 nm. In comparison, the IQEs of the charge transfer (CT) sensitizer cells are 10-30% lower in the same wavelength range. The enhanced IQE values in the devices based on the CS sensitizers are ascribed to the higher electron injection efficiencies and slower charge recombination. The results demonstrate that taking advantage of the CS states in the sensitizers can be a promising strategy to improve the IQEs and further enhance the overall efficiencies of the DSSCs.

  18. Creation of Superheterojunction Polymers via Direct Polycondensation: Segregated and Bicontinuous Donor-Acceptor π-Columnar Arrays in Covalent Organic Frameworks for Long-Lived Charge Separation. (United States)

    Jin, Shangbin; Supur, Mustafa; Addicoat, Matthew; Furukawa, Ko; Chen, Long; Nakamura, Toshikazu; Fukuzumi, Shunichi; Irle, Stephan; Jiang, Donglin


    By developing metallophthalocyanines and diimides as electron-donating and -accepting building blocks, herein, we report the construction of new electron donor-acceptor covalent organic frameworks (COFs) with periodically ordered electron donor and acceptor π-columnar arrays via direct polycondensation reactions. X-ray diffraction measurements in conjunction with structural simulations resolved that the resulting frameworks consist of metallophthalocyanine and diimide columns, which are ordered in a segregated yet bicontinuous manner to form built-in periodic π-arrays. In the frameworks, each metallophthalocyanine donor and diimide acceptor units are exactly linked and interfaced, leading to the generation of superheterojunctions-a new type of heterojunction machinery, for photoinduced electron transfer and charge separation. We show that this polycondensation method is widely applicable to various metallophthalocyanines and diimides as demonstrated by the combination of copper, nickel, and zinc phthalocyanine donors with pyrommellitic diimide, naphthalene diimide, and perylene diimide acceptors. By using time-resolved transient absorption spectroscopy and electron spin resonance, we demonstrated that the COFs enable long-lived charge separation, whereas the metal species, the class of acceptors, and the local geometry between donor and acceptor units play roles in determining the photochemical dynamics. The results provide insights into photoelectric COFs and demonstrate their enormous potential for charge separation and photoenergy conversions.

  19. Charge Separation in Intermixed Polymer:PC70BM Photovoltaic Blends: Correlating Structural and Photophysical Length Scales as a Function of Blend Composition

    KAUST Repository

    Utzat, Hendrik


    A key challenge in achieving control over photocurrent generation by bulk-heterojunction organic solar cells is understanding how the morphology of the active layer impacts charge separation and in particular the separation dynamics within molecularly intermixed donor-acceptor domains versus the dynamics between phase-segregated domains. This paper addresses this issue by studying blends and devices of the amorphous silicon-indacenodithiophene polymer SiIDT-DTBT and the acceptor PCBM. By changing the blend composition, we modulate the size and density of the pure and intermixed domains on the nanometer length scale. Laser spectroscopic studies show that these changes in morphology correlate quantitatively with the changes in charge separation dynamics on the nanosecond time scale and with device photocurrent densities. At low fullerene compositions, where only a single, molecularly intermixed polymer-fullerene phase is observed, photoexcitation results in a ∼ 30% charge loss from geminate polaron pair recombination, which is further studied via light intensity experiments showing that the radius of the polaron pairs in the intermixed phase is 3-5 nm. At high fullerene compositions (≥67%), where the intermixed domains are 1-3 nm and the pure fullerene phases reach ∼4 nm, the geminate recombination is suppressed by the reduction of the intermixed phase, making the fullerene domains accessible for electron escape.

  20. Assessing the additive risks of PSII herbicide exposure to the Great Barrier Reef. (United States)

    Lewis, Stephen E; Schaffelke, Britta; Shaw, Melanie; Bainbridge, Zoë T; Rohde, Ken W; Kennedy, Karen; Davis, Aaron M; Masters, Bronwyn L; Devlin, Michelle J; Mueller, Jochen F; Brodie, Jon E


    Herbicide residues have been measured in the Great Barrier Reef lagoon at concentrations which have the potential to harm marine plant communities. Monitoring on the Great Barrier Reef lagoon following wet season discharge show that 80% of the time when herbicides are detected, more than one are present. These herbicides have been shown to act in an additive manner with regards to photosystem-II inhibition. In this study, the area of the Great Barrier Reef considered to be at risk from herbicides is compared when exposures are considered for each herbicide individually and also for herbicide mixtures. Two normalisation indices for herbicide mixtures were calculated based on current guidelines and PSII inhibition thresholds. The results show that the area of risk for most regions is greatly increased under the proposed additive PSII inhibition threshold and that the resilience of this important ecosystem could be reduced by exposure to these herbicides. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. From Recombination Dynamics to Device Performance: Quantifying the Efficiency of Exciton Dissociation, Charge Separation, and Extraction in Bulk Heterojunction Solar Cells with Fluorine-Substituted Polymer Donors

    KAUST Repository

    Gorenflot, Julien


    An original set of experimental and modeling tools is used to quantify the yield of each of the physical processes leading to photocurrent generation in organic bulk heterojunction solar cells, enabling evaluation of materials and processing condition beyond the trivial comparison of device performances. Transient absorption spectroscopy, “the” technique to monitor all intermediate states over the entire relevant timescale, is combined with time-delayed collection field experiments, transfer matrix simulations, spectral deconvolution, and parametrization of the charge carrier recombination by a two-pool model, allowing quantification of densities of excitons and charges and extrapolation of their kinetics to device-relevant conditions. Photon absorption, charge transfer, charge separation, and charge extraction are all quantified for two recently developed wide-bandgap donor polymers: poly(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-difluorothiophene) (PBDT[2F]T) and its nonfluorinated counterpart poly(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-thiophene) (PBDT[2H]T) combined with PC71BM in bulk heterojunctions. The product of these yields is shown to agree well with the devices\\' external quantum efficiency. This methodology elucidates in the specific case studied here the origin of improved photocurrents obtained when using PBDT[2F]T instead of PBDT[2H]T as well as upon using solvent additives. Furthermore, a higher charge transfer (CT)-state energy is shown to lead to significantly lower energy losses (resulting in higher VOC) during charge generation compared to P3HT:PCBM.

  2. Deletion of CGLD1 Impairs PSII and Increases Singlet Oxygen Tolerance of Green Alga Chlamydomonas reinhardtii

    Directory of Open Access Journals (Sweden)

    Jiale Xing


    Full Text Available The green alga Chlamydomonas reinhardtii is a key model organism for studying photosynthesis and oxidative stress in unicellular eukaryotes. Using a forward genetics approach, we have identified and characterized a mutant x32, which lacks a predicted protein named CGLD1 (Conserved in Green Lineage and Diatom 1 in GreenCut2, under normal and stress conditions. We show that loss of CGLD1 resulted in minimal photoautotrophic growth and PSII activity in the organism. We observed reduced amount of PSII complex and core subunits in the x32 mutant based on blue-native (BN/PAGE and immunoblot analysis. Moreover, x32 exhibited increased sensitivity to high-light stress and altered tolerance to different reactive oxygenic species (ROS stress treatments, i.e., decreased resistance to H2O2/or tert-Butyl hydroperoxide (t-BOOH and increased tolerance to neutral red (NR and rose bengal (RB that induce the formation of singlet oxygen, respectively. Further analysis via quantitative real-time PCR (qRT-PCR indicated that the increased singlet-oxygen tolerance of x32 was largely correlated with up-regulated gene expression of glutathione-S-transferases (GST. The phenotypical and physiological implications revealed from our experiments highlight the important roles of CGLD1 in maintaining structure and function of PSII as well as in protection of Chlamydomonas under photo-oxidative stress conditions.

  3. Enhanced Charge Separation in Ternary P3HT/PCBM/CuInS2 Nanocrystals Hybrid Solar Cells

    NARCIS (Netherlands)

    Lefrançois, Aurélie; Luszczynska, Beata; Pepin-Donat, Brigitte; Lombard, Christian; Bouthinon, Benjamin; Verilhac, Jean-Marie; Gromova, Marina; Faure-Vincent, Jérôme; Pouget, Stéphanie; Chandezon, Frédéric; Sadki, Saïd; Reiss, Peter


    Geminate recombination of bound polaron pairs at the donor/acceptor interface is one of the major loss mechanisms in organic bulk heterojunction solar cells. One way to overcome Coulomb attraction between opposite charge carriers and to achieve their full dissociation is the introduction of high

  4. Highly-Efficient Charge Separation and Polaron Delocalization in Polymer-Fullerene Bulk-Heterojunctions: A Comparative Multi-Frequency EPR & DFT Study (United States)

    Niklas, Jens; Mardis, Kristy L.; Banks, Brian P.; Grooms, Gregory M.; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G.


    The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Under illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P+, and negative, P-, polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of 1H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40 - 60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR. Strong

  5. Efficient charge separation based on type-II g-C3N4/TiO2-B nanowire/tube heterostructure photocatalysts. (United States)

    Chen, Hongmei; Xie, Yinghao; Sun, Xiaoqin; Lv, Meilin; Wu, Fangfang; Zhang, Lei; Li, Li; Xu, Xiaoxiang


    Separation of photo-generated charges has played a crucial role in controlling the actual performance of a photocatalytic system. Here we have successfully fabricated g-C3N4/TiO2-B nanowire/tube heterostructures through facile urea degradation reactions. Owing to the effective separation of photo-generated charges associated with the type-II band alignment and intimate interfacial contacts between g-C3N4 and TiO2-B nanowires/tubes, such heterostructures demonstrate an improved photocatalytic activity over individual moieties. Synthetic conditions such as hydrothermal temperatures for the preparation of TiO2-B and the weight ratio of TiO2-B to urea were systematically investigated. A high crystallinity of TiO2-B as well as the proper growth of g-C3N4 on its surface are critical factors for a better performance. Our simple synthetic method and the prolonged lifetime of photo-generated charges signify the importance of type-II heterostructures in the photocatalytic applications.

  6. Stoichiometric relationship between the (Mn){sub 4}-cluster and PSII Ca{sup 2+} necessary for O{sub 2}-evolution. Final report

    Energy Technology Data Exchange (ETDEWEB)



    This report focuses on the following research accomplishments: Stoichiometric relationship between the (Mn){sub 4}-cluster and PSII Ca{sup 2+} necessary for O{sub 2}-evolution; Photodamage of Mn-depleted PSII membranes: Sites and mechanisms of photoinactivation of primary reactions; The photoassembly of the PSII (Mn){sub 4}cluster is modulated by Ca{sup 2+} and DCIP; The natural product sorgoleone inhibits electron transfer at the Q{sub A}/Q{sub B} site of PSII; and Photodamages of Ca{sup 2+}-depleted PSII membranes: Sites and mechanisms of inactivation of donor side reactions.

  7. Charge pattern matching as a ‘fuzzy’ mode of molecular recognition for the functional phase separations of intrinsically disordered proteins (United States)

    Lin, Yi-Hsuan; Brady, Jacob P.; Forman-Kay, Julie D.; Chan, Hue Sun


    Biologically functional liquid–liquid phase separation of intrinsically disordered proteins (IDPs) is driven by interactions encoded by their amino acid sequences. Little is currently known about the molecular recognition mechanisms for distributing different IDP sequences into various cellular membraneless compartments. Pertinent physics was addressed recently by applying random-phase-approximation (RPA) polymer theory to electrostatics, which is a major energetic component governing IDP phase properties. RPA accounts for charge patterns and thus has advantages over Flory–Huggins (FH) and Overbeek–Voorn mean-field theories. To make progress toward deciphering the phase behaviors of multiple IDP sequences, the RPA formulation for one IDP species plus solvent is hereby extended to treat polyampholyte solutions containing two IDP species plus solvent. The new formulation generally allows for binary coexistence of two phases, each containing a different set of volume fractions ({φ }1,{φ }2) for the two different IDP sequences. The asymmetry between the two predicted coexisting phases with regard to their {φ }1/{φ }2 ratios for the two sequences increases with increasing mismatch between their charge patterns. This finding points to a multivalent, stochastic, ‘fuzzy’ mode of molecular recognition that helps populate various IDP sequences differentially into separate phase compartments. An intuitive illustration of this trend is provided by FH models, whereby a hypothetical case of ternary coexistence is also explored. Augmentations of the present RPA theory with a relative permittivity {ε }{{r}}(φ ) that depends on IDP volume fraction φ ={φ }1+{φ }2 lead to higher propensities to phase separate, in line with the case with one IDP species we studied previously. Notably, the cooperative, phase-separation-enhancing effects predicted by the prescriptions for {ε }{{r}}(φ ) we deem physically plausible are much more prominent than that entailed by common

  8. Modeling of the charge-state separation at ITEP experimental facility for material science based on a Bernas ion source. (United States)

    Barminova, H Y; Saratovskyh, M S


    The experiment automation system is supposed to be developed for experimental facility for material science at ITEP, based on a Bernas ion source. The program CAMFT is assumed to be involved into the program of the experiment automation. CAMFT is developed to simulate the intense charged particle bunch motion in the external magnetic fields with arbitrary geometry by means of the accurate solution of the particle motion equation. Program allows the consideration of the bunch intensity up to 10(10) ppb. Preliminary calculations are performed at ITEP supercomputer. The results of the simulation of the beam pre-acceleration and following turn in magnetic field are presented for different initial conditions.

  9. Electric Double Layer Composed of an Antagonistic Salt in an Aqueous Mixture: Local Charge Separation and Surface Phase Transition (United States)

    Yabunaka, Shunsuke; Onuki, Akira


    We examine an electric double layer containing an antagonistic salt in an aqueous mixture, where the cations are small and hydrophilic but the anions are large and hydrophobic. In this situation, a strong coupling arises between the charge density and the solvent composition. As a result, the anions are trapped in an oil-rich adsorption layer on a hydrophobic wall. We then vary the surface charge density σ on the wall. For σ >0 the anions remain accumulated, but for σ cations are attracted to the wall with increasing |σ |. Furthermore, the electric potential drop Ψ (σ ) is nonmonotonic when the solvent interaction parameter χ (T ) exceeds a critical value χc determined by the composition and the ion density in the bulk. This leads to a first-order phase transition between two kinds of electric double layers with different σ and common Ψ . In equilibrium such two-layer regions can coexist. The steric effect due to finite ion sizes is crucial in these phenomena.

  10. Validation of a pH gradient-based ion-exchange chromatography method for high-resolution monoclonal antibody charge variant separations. (United States)

    Rea, Jennifer C; Moreno, G Tony; Lou, Yun; Farnan, Dell


    Ion-exchange chromatography is widely used for profiling the charge heterogeneity of proteins, including monoclonal antibodies. Despite good resolving power and robustness, ionic strength-based ion-exchange separations are product-specific and time-consuming to develop. We have previously reported a novel pH-based separation of proteins by cation exchange chromatography that was multi-product, high-resolution, and robust against variations in sample matrix salt concentration and pH. In this study, a pH gradient-based separation method using cation exchange chromatography was evaluated in a mock validation. This method was shown to be robust for monoclonal antibodies and suitable for its intended purpose of charge heterogeneity analysis. Simple mixtures of defined buffer components were used to generate the pH gradients that separated closely related antibody species. Validation characteristics, such as precision and linearity, were evaluated. Robustness to changes in protein load, buffer pH and column oven temperature was demonstrated. The stability-indicating capability of this method was determined using thermally stressed antibody samples. In addition, intermediate precision was demonstrated using multiple instruments, multiple analysts, multiple column lots, and different column manufacturers. Finally, the precision for this method was compared to conventional ion-exchange chromatography and imaged capillary isoelectric focusing. These results demonstrate the superior precision and robustness of this multi-product method, which can be used for the high-throughput evaluation of in-process and final product samples. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Sequential bond energies and barrier heights for the water loss and charge separation dissociation pathways of Cd(2+)(H2O)n, n = 3-11. (United States)

    Cooper, Theresa E; Armentrout, P B


    The bond dissociation energies for losing one water from Cd(2+)(H(2)O)(n) complexes, n = 3-11, are measured using threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer coupled with a thermal electrospray ionization source. Kinetic energy dependent cross sections are obtained for n = 4-11 complexes and analyzed to yield 0 K threshold measurements for loss of one, two, and three water ligands after accounting for multiple collisions, kinetic shifts, and energy distributions. The threshold measurements are converted from 0 to 298 K values to give the hydration enthalpies and free energies for sequentially losing one water from each complex. Theoretical geometry optimizations and single point energy calculations are performed on reactant and product complexes using several levels of theory and basis sets to obtain thermochemistry for comparison to experiment. The charge separation process, Cd(2+)(H(2)O)(n) → CdOH(+)(H(2)O)(m) + H(+)(H(2)O)(n-m-1), is also observed for n = 4 and 5 and the competition between this process and water loss is analyzed. Rate-limiting transition states for the charge separation process at n = 3-6 are calculated and compared to experimental threshold measurements resulting in the conclusion that the critical size for this dissociation pathway of hydrated cadmium is n(crit) = 4.

  12. Femtosecond spectroscopy of the primary charge separation in reaction centers of Chloroflexus aurantiacus with selective excitation in the QY and Soret bands. (United States)

    Xin, Yueyong; Lin, Su; Blankenship, Robert E


    The primary charge separation and electron-transfer processes of photosynthesis occur in the reaction center (RC). Isolated RCs of the green filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus were studied at room temperature by using femtosecond transient absorption spectroscopy with selective excitation. Upon excitation in the Q(Y) absorbance band of the bacteriochlorophyll (BChl) dimer (P) at 865 nm, a 7.0 +/- 0.5 ps kinetic component was observed in the 538 nm region (Q(X) band of the bacteriopheophytin (BPheo)), 750 nm region (Q(Y) band of the BPheo), and 920 nm region (stimulated emission of the excited-state of P), indicating that this lifetime represents electron transfer from P to BPheo. The same time constant was also observed upon 740 nm or 800 nm excitation. A longer lifetime (300 +/- 30 ps), which was assigned to the time of reduction of the primary quinone, Q(A), was also observed. The transient absorption spectra and kinetics all indicate that only one electron-transfer branch is involved in primary charge separation under these excitation conditions. However, the transient absorption changes upon excitation in the Soret band at 390 nm reveal a more complex set of energy and electron-transfer processes. By comparison to studies on the RCs of the purple bacterium Rhodobacter sphaeroides, we discuss the possible mechanism of electron-transfer pathway dependence on excitation energy and propose a model of the Cf. aurantiacus RC that better explains the observed results.

  13. Isolation of novel PSII-LHCII megacomplexes from pea plants characterized by a combination of proteomics and electron microscopy. (United States)

    Albanese, Pascal; Nield, Jon; Tabares, Jose Alejandro Muñoz; Chiodoni, Angelica; Manfredi, Marcello; Gosetti, Fabio; Marengo, Emilio; Saracco, Guido; Barber, James; Pagliano, Cristina


    In higher plants, photosystem II (PSII) is a multi-subunit pigment-protein complex embedded in the thylakoid membranes of chloroplasts, where it is present mostly in dimeric form within the grana. Its light-harvesting antenna system, LHCII, is composed of trimeric and monomeric complexes, which can associate in variable number with the dimeric PSII core complex in order to form different types of PSII-LHCII supercomplexes. Moreover, PSII-LHCII supercomplexes can laterally associate within the thylakoid membrane plane, thus forming higher molecular mass complexes, termed PSII-LHCII megacomplexes (Boekema et al. 1999a, in Biochemistry 38:2233-2239; Boekema et al. 1999b, in Eur J Biochem 266:444-452). In this study, pure PSII-LHCII megacomplexes were directly isolated from stacked pea thylakoid membranes by a rapid single-step solubilization, using the detergent n-dodecyl-α-D-maltoside, followed by sucrose gradient ultracentrifugation. The megacomplexes were subjected to biochemical and structural analyses. Transmission electron microscopy on negatively stained samples, followed by single-particle analyses, revealed a novel form of PSII-LHCII megacomplexes, as compared to previous studies (Boekema et al.1999a, in Biochemistry 38:2233-2239; Boekema et al. 1999b, in Eur J Biochem 266:444-452), consisting of two PSII-LHCII supercomplexes sitting side-by-side in the membrane plane, sandwiched together with a second copy. This second copy of the megacomplex is most likely derived from the opposite membrane of a granal stack. Two predominant forms of intact sandwiched megacomplexes were observed and termed, according to (Dekker and Boekema 2005 Biochim Biophys Acta 1706:12-39), as (C2S2)4 and (C2S2 + C2S2M2)2 megacomplexes. By applying a gel-based proteomic approach, the protein composition of the isolated megacomplexes was fully characterized. In summary, the new structural forms of isolated megacomplexes and the related modeling performed provide novel insights into

  14. Influence of Blend Morphology and Energetics on Charge Separation and Recombination Dynamics in Organic Solar Cells Incorporating a Nonfullerene Acceptor

    KAUST Repository

    Cha, Hyojung


    Nonfullerene acceptors (NFAs) in blends with highly crystalline donor polymers have been shown to yield particularly high device voltage outputs, but typically more modest quantum yields for photocurrent generation as well as often lower fill factors (FF). In this study, we employ transient optical and optoelectronic analysis to elucidate the factors determining device photocurrent and FF in blends of the highly crystalline donor polymer PffBT4T-2OD with the promising NFA FBR or the more widely studied fullerene acceptor PC71BM. Geminate recombination losses, as measured by ultrafast transient absorption spectroscopy, are observed to be significantly higher for PffBT4T-2OD:FBR blends. This is assigned to the smaller LUMO-LUMO offset of the PffBT4T-2OD:FBR blends relative to PffBT4T-2OD:PC71BM, resulting in the lower photocurrent generation efficiency obtained with FBR. Employing time delayed charge extraction measurements, these geminate recombination losses are observed to be field dependent, resulting in the lower FF observed with PffBT4T-2OD:FBR devices. These data therefore provide a detailed understanding of the impact of acceptor design, and particularly acceptor energetics, on organic solar cell performance. Our study concludes with a discussion of the implications of these results for the design of NFAs in organic solar cells.

  15. Spin dynamics of light-induced charge separation in composites of semiconducting polymers and PC60BM revealed using Q-band pulse EPR. (United States)

    Lukina, E A; Suturina, E; Reijerse, E; Lubitz, W; Kulik, L V


    Light-induced processes in composites of semiconducting polymers and fullerene derivatives have been widely studied due to their usage as active layers of organic solar cells. However the process of charge separation under light illumination - the key process of an organic solar cell is not well understood yet. Here we report a Q-band pulse electron paramagnetic resonance study of composites of the fullerene derivative PC 60 BM ([6,6]-phenyl-C 61 -butyric acid methyl ester) with different p-type semiconducting polymers regioregular and regiorandom P3HT (poly(3-hexylthiophene-2,5-diyl), MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]), PCDTBT (poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]), PTB7 (poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}))), resulting in a detailed description of the in-phase laser flash-induced electron spin echo (ESE) signal. We found that in organic donor-acceptor composites the laser flash simultaneously induces species of two types: a polymer˙ + /fullerene˙ - spin-correlated polaron pair (SCPP) with an initial singlet spin state and (nearly) free polymer˙ + and fullerene˙ - species with non-equilibrium spin polarization. Species of the first type (SCPP) are well-known for polymer/fullerene blends and are usually associated with a charge-separated state. Also, spin polarization of long-living free species (polarons in deep traps) is affected by the laser flash, which is the third contribution to the flash-induced ESE signal. A protocol for extracting the in-phase ESE signal of the SCPP based on the dependence of the microwave nutation frequency on the strength of the spin coupling within the polaron pair was developed. Nutation experiments revealed an unusual pattern of the SCPP in RR-P3HT/PC 60 BM composites, from which the strength of the exchange interaction between the polymer

  16. Solar UV-B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, Helge


    The long-term and diurnal responses of photosystem II (PSII) performance to near-ambient UV-B radiation were investigated in High Arctic Betula nana. We conducted an UV exclusion experiment with five replicated blocks consisting of open control (no filter), photosynthetic active radiation and UV...... the effects of UV-B. Chlorophyll-a fluorescence induction curves were used for analysis of OJIP test parameters. Near-ambient UV-B radiation reduced across season maximum quantum yield (TRo /ABS = Fv /Fm ), approximated number of active PSII reaction center (RC/ABS) and the performance index (PIABS ), despite...... in reduced UV-B compared to near-ambient UV-B. This demonstrates current solar UV-B to reduce the PSII performance both on a daily as well as a seasonal basis in this High Arctic species....

  17. Antagonism between elevated CO2, nighttime warming, and summer drought reduces the robustness of PSII performance to freezing events

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Boesgaard, Kristine Stove; Ro-Poulsen, Helge


    out in the CLIMAITE multifactor experiment, which includes the combined impact of elevated CO2 (free air carbon enrichment; CO2), warming (passive nighttime warming; T) and summer drought (rain-excluding curtains; D) in a temperate heath ecosystem. PSII performance was probed by the effective quantum...... in the wavy hair-grass, Deschampsia flexuosa, and in the evergreen dwarf shrub common heather, Calluna vulgaris, and following freezing events the PItotal and Fv′/Fm′ were reduced even more. Contrary to expected, indirect effects of the previous summer drought reduced PSII performance before freezing events......, particularly in Calluna. In combinations with elevated CO2 interactive effects with drought, D×CO2 and warming, T×D×CO2, were negatively skewed and caused the reduction of PSII performance in both species after occurrence of freezing events. Neither passive nighttime warming nor elevated CO2 as single factors...

  18. Variations in morphology and PSII photosynthetic capabilities during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi) Papenfuss (Gracilariales, Rhodophyta). (United States)

    Xie, Xiujun; Wang, Guangce; Pan, Guanghua; Gao, Shan; Xu, Pu; Zhu, Jianyi


    Red algae are primitive photosynthetic eukaryotes, whose spores are ideal subjects for studies of photosynthesis and development. Although the development of red alga spores has received considerable research attention, few studies have focused on the detailed morphological and photosynthetic changes that occur during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi) Papenfuss (Gracilariales, Rhodophyta). Herein, we documented these changes in this species of red algae. In the tetraspores, we observed two types of division, cruciate and zonate, and both could develop into multicellular bodies (disks). During the first 84 hours, tetraspores divided several times, but the diameter of the disks changed very little; thereafter, the diameter increased significantly. Scanning electron microscopy observations and analysis of histological sections revealed that the natural shape of the disk remains tapered over time, and the erect frond grows from the central protrusion of the disk. Cultivation of tissue from excised disks demonstrated that the central protrusion of the disk is essential for initiation of the erect frond. Photosynthetic (i.e., PSII) activities were measured using chlorophyll fluorescence analysis. The results indicated that freshly released tetraspores retained limited PSII photosynthetic capabilities; when the tetraspores attached to a substrate, those capabilities increased significantly. In the disk, the PSII activity of both marginal and central cells was similar, although some degree of morphological polarity was present; the PSII photosynthetic capabilities in young germling exhibited an apico-basal gradient. Attachment of tetraspores to a substrate significantly enhanced their PSII photosynthetic capabilities, and triggered further development. The central protrusion of the disk is the growth point, may have transfer of nutritive material with the marginal cells. Within the young germling, the hetero-distribution of PSII

  19. Variations in morphology and PSII photosynthetic capabilities during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi Papenfuss (Gracilariales, Rhodophyta

    Directory of Open Access Journals (Sweden)

    Gao Shan


    Full Text Available Abstract Background Red algae are primitive photosynthetic eukaryotes, whose spores are ideal subjects for studies of photosynthesis and development. Although the development of red alga spores has received considerable research attention, few studies have focused on the detailed morphological and photosynthetic changes that occur during the early development of tetraspores of Gracilaria vermiculophylla (Ohmi Papenfuss (Gracilariales, Rhodophyta. Herein, we documented these changes in this species of red algae. Results In the tetraspores, we observed two types of division, cruciate and zonate, and both could develop into multicellular bodies (disks. During the first 84 hours, tetraspores divided several times, but the diameter of the disks changed very little; thereafter, the diameter increased significantly. Scanning electron microscopy observations and analysis of histological sections revealed that the natural shape of the disk remains tapered over time, and the erect frond grows from the central protrusion of the disk. Cultivation of tissue from excised disks demonstrated that the central protrusion of the disk is essential for initiation of the erect frond. Photosynthetic (i.e., PSII activities were measured using chlorophyll fluorescence analysis. The results indicated that freshly released tetraspores retained limited PSII photosynthetic capabilities; when the tetraspores attached to a substrate, those capabilities increased significantly. In the disk, the PSII activity of both marginal and central cells was similar, although some degree of morphological polarity was present; the PSII photosynthetic capabilities in young germling exhibited an apico-basal gradient. Conclusions Attachment of tetraspores to a substrate significantly enhanced their PSII photosynthetic capabilities, and triggered further development. The central protrusion of the disk is the growth point, may have transfer of nutritive material with the marginal cells. Within

  20. Comparison of TiO₂ and ZnO solar cells sensitized with an indoline dye: time-resolved laser spectroscopy studies of partial charge separation processes. (United States)

    Sobuś, Jan; Burdziński, Gotard; Karolczak, Jerzy; Idígoras, Jesús; Anta, Juan A; Ziółek, Marcin


    Time-resolved laser spectroscopy techniques in the time range from femtoseconds to seconds were applied to investigate the charge separation processes in complete dye-sensitized solar cells (DSC) made with iodide/iodine liquid electrolyte and indoline dye D149 interacting with TiO2 or ZnO nanoparticles. The aim of the studies was to explain the differences in the photocurrents of the cells (3-4 times higher for TiO2 than for ZnO ones). Electrochemical impedance spectroscopy and nanosecond flash photolysis studies revealed that the better performance of TiO2 samples is not due to the charge collection and dye regeneration processes. Femtosecond transient absorption results indicated that after first 100 ps the number of photoinduced electrons in the semiconductor is 3 times higher for TiO2 than for ZnO solar cells. Picosecond emission studies showed that the lifetime of the D149 excited state is about 3 times longer for ZnO than for TiO2 samples. Therefore, the results indicate that lower performance of ZnO solar cells is likely due to slower electron injection. The studies show how to correlate the laser spectroscopy methodology with global parameters of the solar cells and should help in better understanding of the behavior of alternative materials for porous electrodes for DSC and related devices.

  1. Structure of PSI, PSII and antennae complexes from yellow-green alga Xanthonema debile. (United States)

    Gardian, Zdenko; Tichý, Josef; Vácha, František


    Photosynthetic carbon fixation by Chromophytes is one of the significant components of a carbon cycle on the Earth. Their photosynthetic apparatus is different in pigment composition from that of green plants and algae. In this work we report structural maps of photosystem I, photosystem II and light harvesting antenna complexes isolated from a soil chromophytic alga Xanthonema debile (class Xanthophyceae). Electron microscopy of negatively stained preparations followed by single particle analysis revealed that the overall structure of Xanthophytes' PSI and PSII complexes is similar to that known from higher plants or algae. Averaged top-view projections of Xanthophytes' light harvesting antenna complexes (XLH) showed two groups of particles. Smaller ones that correspond to a trimeric form of XLH, bigger particles resemble higher oligomeric form of XLH.

  2. Ambient UV-B radiation reduces PSII performance and net photosynthesis in high Arctic Salix arctica

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.


    Ambient ultraviolet-B (UV-B) radiation potentially impacts the photosynthetic performance of high Arctic plants. We conducted an UV-B exclusion experiment in a dwarf shrub heath in NE Greenland (74°N), with open control, filter control, UV-B filtering and UV-AB filtering, all in combination...... was characterized by simultaneous gas exchange and chlorophyll fluorescence measurements and the PSII performance through the growing season was investigated with fluorescence measurements. Leaf harvest towards the end of the growing season was done to determine the specific leaf area and the content of carbon......, nitrogen and UV-B absorbing compounds. Compared to a 60% reduced UV-B irradiance, the ambient solar UV-B reduced net photosynthesis in Salix arctica leaves fixed in the 45° position which exposed leaves to maximum natural irradiance. Also a reduced Calvin Cycle capacity was found, i.e. the maximum rate...

  3. Effect of leaf dehydration duration and dehydration degree on PSII photochemical activity of papaya leaves. (United States)

    Liu, Meijun; Zhang, Zishan; Gao, Huiyuan; Yang, Cheng; Fan, Xingli; Cheng, Dandan


    Although the effect of dehydration on photosynthetic apparatus has been widely studied, the respective effect of dehydration duration and dehydration degree was neglected. This study showed that, when leaves dehydrated in air, the PSII activities of leaves decreased with the decline of leaf relative water content (RWC). Unexpectedly, when leaves dehydrated to same RWC, the decreases in Fv/Fm, Ψo and RC/CSm were lower in leaves dehydrating at 43 °C than those at 25 °C. However, to reach the same RWC, leaves dehydrating at 43 °C experienced 1/6 of the dehydration duration for leaves dehydrating at 25 °C. To distinguish the respective effect of dehydration degree and dehydration duration on photosynthetic apparatus, we studied the PSII activities of leaves treated with different concentration of PEG solutions. Increasing dehydration degree aggravated the decline of Fv/Fm, Ψo and RC/CSm in leaves with the same dehydration duration, while prolonging the dehydration duration also exacerbated the decline of Fv/Fm, Ψo and RC/CSm in leaves with identical dehydration degree. With the same dehydration degree and duration, high temperature enhanced the decrease of Fv/Fm, Ψo and RC/CSm in the leaves. When leaves dehydrated in air, the effect of high temperature was underestimated due to reduction of dehydration duration. The results demonstrated that, dehydration degree and duration both play important roles in damage to photosynthetic apparatus. We suggest that, under combined stresses, the effects of dehydration degree and duration on plants should be considered comprehensively, otherwise, partial or incorrect results may be obtained. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  4. High resolution separations of charge variants and disulfide isomers of monoclonal antibodies and antibody drug conjugates using ultra-high voltage capillary electrophoresis with high electric field strength. (United States)

    Henley, W Hampton; He, Yan; Mellors, J Scott; Batz, Nicholas G; Ramsey, J Michael; Jorgenson, James W


    Ultra-high voltage capillary electrophoresis with high electric field strength has been applied to the separation of the charge variants, drug conjugates, and disulfide isomers of monoclonal antibodies. Samples composed of many closely related species are difficult to resolve and quantify using traditional analytical instrumentation. High performance instrumentation can often save considerable time and effort otherwise spent on extensive method development. Ideally, the resolution obtained for a given CE buffer system scales with the square root of the applied voltage. Currently available commercial CE instrumentation is limited to an applied voltage of approximately 30kV and a maximum electric field strength of 1kV/cm due to design limitations. The instrumentation described here is capable of safely applying potentials of at least 120kV with electric field strengths over 2000V/cm, potentially doubling the resolution of the best conventional CE buffer/capillary systems while decreasing analysis time in some applications. Separations of these complex mixtures using this new instrumentation demonstrate the potential of ultra-high voltage CE to identify the presence of previously unresolved components and to reduce analysis time for complex mixtures of antibody variants and drug conjugates. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Description of the Charge Transfer States at the Pentacene/C60 Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

    KAUST Repository

    Zheng, Zilong


    Density functional theory (DFT) approaches based on range-separated hybrid functionals are currently methods of choice for the description of the charge-transfer (CT) states in organic donor/acceptor solar cells. However, these calculations are usually performed on small-size donor/acceptor complexes and as result do not account for electronic polarization effects. Here, using a pentacene/C60 complex as a model system, we discuss the ability of long-range corrected (LCR) hybrid functionals in combination with the polarizable continuum model (PCM) to determine the impact of the solid-state environment on the CT states. The CT energies are found to be insensitive to the interactions with the dielectric medium when a conventional time-dependent DFT/PCM (TDDFT/PCM) approach is used. However, a decrease in the energy of the CT state in the framework of LRC functionals can be obtained by using a smaller range-separated parameter when going from an isolated donor/acceptor complex to the solid-state case.

  6. An Anion Metal-Organic Framework with Lewis Basic Sites-Rich toward Charge-Exclusive Cationic Dyes Separation and Size-Selective Catalytic Reaction. (United States)

    Wang, Xu-Sheng; Liang, Jun; Li, Lan; Lin, Zu-Jin; Bag, Partha Pratim; Gao, Shui-Ying; Huang, Yuan-Biao; Cao, Rong


    Organic dye pollutants become a big headache due to their toxic nature to the environment, and it should be one of the best solutions if we can separate and reuse them. Here, we report the synthesis and characterization of a microporous anion metal-organic framework (MOF) with Lewis basic sites-rich based on TDPAT (2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) ligand, FJI-C2, which shows high adsorption and separation of cationic dye based on the charge-exclusive effect. Compared to other MOF materials, FJI-C2 shows the largest adsorption amount of methylene blue (1323 mg/g) at room temperature due to the nature of the anion frameworks and high surface area/pore volume. Furthermore, motivated by the adsorption properties of large guest molecules, we proceeded to investigate the catalytic behaviors of FJI-C2, not only because the large pore facilitates the mass transfer of guest molecules but also because the high density of Lewis basic sites can act as effective catalytic sites. As expected, FJI-C2 exhibits excellent catalytic performance for size-selective Knoevenagel condensation under mild conditions and can be reused several times without a significant decrease of the activity.

  7. Adverse Effects of Excess Residual PbI2on Photovoltaic Performance, Charge Separation, and Trap-State Properties in Mesoporous Structured Perovskite Solar Cells. (United States)

    Wang, Hao-Yi; Hao, Ming-Yang; Han, Jun; Yu, Man; Qin, Yujun; Zhang, Pu; Guo, Zhi-Xin; Ai, Xi-Cheng; Zhang, Jian-Ping


    Organic-inorganic halide perovskite solar cells have rapidly come to prominence in the photovoltaic field. In this context, CH 3 NH 3 PbI 3 , as the most widely adopted active layer, has been attracting great attention. Generally, in a CH 3 NH 3 PbI 3 layer, unreacted PbI 2 inevitably coexists with the perovskite crystals, especially following a two-step fabrication process. There appears to be a consensus that an appropriate amount of unreacted PbI 2 is beneficial to the overall photovoltaic performance of a device, the only disadvantageous aspect of excess residual PbI 2 being viewed as its insulating nature. However, the further development of such perovskite-based devices requires a deeper understanding of the role of residual PbI 2 . In this work, PbI 2 -enriched and PbI 2 -controlled perovskite films, as two extreme cases, have been prepared by modulating the crystallinity of a pre-deposited PbI 2 film. The effects of excess residual PbI 2 have been elucidated on the basis of spectroscopic and optoelectronic studies. The initial charge separation, the trap-state density, and the trap-state distribution have all been found to be adversely affected in PbI 2 -enriched devices, to the detriment of photovoltaic performance. This leads to a biphasic recombination process and accelerates the charge carrier recombination dynamics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Complete Monitoring of Coherent and Incoherent Spin Flip Domains in the Recombination of Charge-Separated States of Donor-Iridium Complex-Acceptor Triads. (United States)

    Klein, Johannes H; Schmidt, David; Steiner, Ulrich E; Lambert, Christoph


    The spin chemistry of photoinduced charge-separated (CS) states of three triads comprising one or two triarylamine donors, a cyclometalated iridium complex sensitizer and a naphthalene diimide (NDI) acceptor, was investigated by transient absorption spectroscopy in the ns-μs time regime. Strong magnetic-field effects (MFE) were observed for two triads with a phenylene bridge between iridium complex sensitizer and NDI acceptor. For these triads, the lifetimes of the CS states increased from 0.6 μs at zero field to 40 μs at about 2 T. Substituting the phenylene by a biphenyl bridge causes the lifetime of the CS state at zero field to increase by more than 2 orders of magnitude (τ = 79 μs) and the MFE to disappear almost completely. The kinetic MFE was analyzed in the framework of a generalized Hayashi-Nagakura scheme describing coherent (S, T0 ↔ T±) as well as incoherent (S, T0 ⇌ T±) processes by a single rate constant k±. The magnetic-field dependence of k± of the triads with phenylene bridge spans 2 orders of magnitude and exhibits a biphasic behavior characterized by a superposition of two Lorentzians. This biphasic MFE is observed for the first time and is clearly attributable to the coherent (B < 10 mT) and incoherent (10 mT < B < 2 T) domains of spin motion induced by isotropic and anisotropic hyperfine coupling. The parameters of both domains are well understood in terms of the structural properties of the two triads, including the effect of electron hopping in the triad with two donor moieties. The kinetic model also accounts for the reduction of the MFE on reducing the rate constant of charge recombination in the triad with the biphenyl bridge.

  9. Charge separation in photoredox reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kevan, L.


    Electron donors/acceptors in micelle and vesicle interfaces (in surfactants) were studied using ESR, deuterium electron spin echo modulation, and ENDOR. Compounds studied included x-doxylstearic acid, tetramethylbenzidine, alkylmethylviologens, alkylphenothiazines, etc.

  10. Reduced graphene oxide wrapped Bi{sub 2}WO{sub 6} hybrid with ultrafast charge separation and improved photoelectrocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huan [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, PR China (China); Liang, Yinghua, E-mail: [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, PR China (China); College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009, PR China (China); Liu, Li; Hu, Jinshan [College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009, PR China (China); Cui, Wenquan, E-mail: [College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009, PR China (China)


    Highlights: • The rGO wrapped Bi{sub 2}WO{sub 6} photoelectrode was successfully synthesized. • The Bi{sub 2}WO{sub 6}@rGOhighlyincreasedthechargeseparationefficiency. • The photoelectrode exhibited enhanced photoelectrocatalytic degradation for RhB. - Abstract: A reduced graphene oxide (rGO) wrapped Bi{sub 2}WO{sub 6} (Bi{sub 2}WO{sub 6}@rGO) hybrid as photoelectrode for enhanced photoelectrocatalytic (PEC) degradation of organic pollutants is reported, which exhibited excellent charge separation and photoconversion efficiency. The core@shell structured Bi{sub 2}WO{sub 6}@rGO photoelectrode yielded a pronounced 1.56-fold and 23.8-fold photocurrent density at 1.0 V vs. saturated calomel electrode (SCE), than that of loading structured Bi{sub 2}WO{sub 6}-rGO and pure Bi{sub 2}WO{sub 6}. The Bi{sub 2}WO{sub 6}@rGO hybrid exhibited enhanced photoelectrocatalytic efficiency for degradation of Rhodamine B (RhB), which was 43.0% and 65.6% higher than that of photocatalytic (PC) and electrocatalytic (EC) processes, respectively. The enhancement in PEC degradation of RhB benefited from: (1) a strong interaction and a wide range of conjugation were formed in the core@shell system; (2) a 0.26 V of flat band potential was negatively shifted in case of Bi{sub 2}WO{sub 6}@rGO composite; (3) the photogenerated electrons and holes could be spatially separated by external electric potentials.

  11. A self-consistent two-dimensional resistive fluid theory of field-aligned potential structures including charge separation and magnetic and velocity shear (United States)

    Hesse, Michael; Birn, Joachim; Schindler, Karl


    A self-consistent two-fluid theory that includes the magnetic field and shear patterns is developed to model stationary electrostatic structures with field-aligned potential drops. Shear flow is also included in the theory since this seems to be a prominent feature of the structures of interest. In addition, Ohmic dissipation, a Hall term, and pressure gradients in a generalized Ohm's law, modified for cases without quasi-neutrality, are included. In the analytic theory, the electrostatic force is balanced by field-aligned pressure gradients (i.e., thermal effects in the direction of the magnetic field) and by pressure gradients and magnetic stresses in the perpendicular direction. Within this theory, simple examples of applications are presented to demonstrate the kind of solutions resulting from the model. The results show how the effects of charge separation and shear in the magnetic field and the velocity can be combined to form self-consistent structures such as are found to exist above the aurora, suggested also in association with solar flares.

  12. Proteomic characterization and three-dimensional electron microscopy study of PSII-LHCII supercomplexes from higher plants. (United States)

    Pagliano, Cristina; Nield, Jon; Marsano, Francesco; Pape, Tillmann; Barera, Simone; Saracco, Guido; Barber, James


    In higher plants a variable number of peripheral LHCII trimers can strongly (S), moderately (M) or loosely (L) associate with the dimeric PSII core (C2) complex via monomeric Lhcb proteins to form PSII-LHCII supercomplexes with different structural organizations. By solubilizing isolated stacked pea thylakoid membranes either with the α or β isomeric forms of the detergent n-dodecyl-D-maltoside, followed by sucrose density ultracentrifugation, we previously showed that PSII-LHCII supercomplexes of types C2S2M2 and C2S2, respectively, can be isolated [S. Barera et al., Phil. Trans. R Soc. B 67 (2012) 3389-3399]. Here we analysed their protein composition by applying extensive bottom-up and top-down mass spectrometry on the two forms of the isolated supercomplexes. In this way, we revealed the presence of the antenna proteins Lhcb3 and Lhcb6 and of the extrinsic polypeptides PsbP, PsbQ and PsbR exclusively in the C2S2M2 supercomplex. Other proteins of the PSII core complex, common to the C2S2M2 and C2S2 supercomplexes, including the low molecular mass subunits, were also detected and characterized. To complement the proteomic study with structural information, we performed negative stain transmission electron microscopy and single particle analysis on the PSII-LHCII supercomplexes isolated from pea thylakoid membranes solubilized with n-dodecyl-α-D-maltoside. We observed the C2S2M2 supercomplex in its intact form as the largest PSII complex in our preparations. Its dataset was further analysed in silico, together with that of the second largest identified sub-population, corresponding to its C2S2 subcomplex. In this way, we calculated 3D electron density maps for the C2S2M2 and C2S2 supercomplexes, approaching respectively 30 and 28Å resolution, extended by molecular modelling towards the atomic level. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2013. Published by

  13. A High-Energy Charge-Separated State of 1.70 eV from a High-Potential Donor-Acceptor Dyad: A Catalyst for Energy-Demanding Photochemical Reactions. (United States)

    Lim, Gary N; Obondi, Christopher O; D'Souza, Francis


    A high potential donor-acceptor dyad composed of zinc porphyrin bearing three meso-pentafluorophenyl substituents covalently linked to C60 , as a novel dyad capable of generating charge-separated states of high energy (potential) has been developed. The calculated energy of the charge-separated state was found to be 1.70 eV, the highest reported for a covalently linked porphyrin-fullerene dyad. Intramolecular photoinduced electron transfer leading to charge-separated states of appreciable lifetimes in polar and nonpolar solvents has been established from studies involving femto- to nanosecond transient absorption techniques. The high energy stored in the form of charge-separated states along with its persistence of about 50-60 ns makes this dyad a potential electron-transporting catalyst to carry out energy-demanding photochemical reactions. This type of high-energy harvesting dyad is expected to open new research in the areas of artificial photosynthesis especially producing energy (potential) demanding light-to-fuel products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen production. (United States)

    Bayro-Kaiser, Vinzenz; Nelson, Nathan


    The need for energy and the associated burden are ever growing. It is crucial to develop new technologies for generating clean and efficient energy for society to avoid upcoming energetic and environmental crises. Sunlight is the most abundant source of energy on the planet. Consequently, it has captured our interest. Certain microalgae possess the ability to capture solar energy and transfer it to the energy carrier, H2. H2 is a valuable fuel, because its combustion produces only one by-product: water. However, the establishment of an efficient biophotolytic H2 production system is hindered by three main obstacles: (1) the hydrogen-evolving enzyme, [FeFe]-hydrogenase, is highly sensitive to oxygen; (2) energy conversion efficiencies are not economically viable; and (3) hydrogen-producing organisms are sensitive to stressful conditions in large-scale production systems. This study aimed to circumvent the oxygen sensitivity of this process with a cyclic hydrogen production system. This approach required a mutant that responded to high temperatures by reducing oxygen evolution. To that end, we randomly mutagenized the green microalgae, Chlamydomonas reinhardtii, to generate mutants that exhibited temperature-sensitive photoautotrophic growth. The selected mutants were further characterized by their ability to evolve oxygen and hydrogen at 25 and 37 °C. We identified four candidate mutants for this project. We characterized these mutants with PSII fluorescence, P700 absorbance, and immunoblotting analyses. Finally, we demonstrated that these mutants could function in a prototype hydrogen-producing bioreactor. These mutant microalgae represent a novel approach for sustained hydrogen production.

  15. Ultrafast Photoinduced Charge Separation Leading to High-Energy Radical Ion-Pairs in Directly Linked Corrole-C60 and Triphenylamine-Corrole-C60 Donor-Acceptor Conjugates. (United States)

    Sudhakar, Kolanu; Gokulnath, Sabapathi; Giribabu, Lingamallu; Lim, Gary N; Trâm, Tạ; D'Souza, Francis


    Closely positioned donor-acceptor pairs facilitate electron- and energy-transfer events, relevant to light energy conversion. Here, a triad system TPACor-C60 , possessing a free-base corrole as central unit that linked the energy donor triphenylamine (TPA) at the meso position and an electron acceptor fullerene (C60) at the β-pyrrole position was newly synthesized, as were the component dyads TPA-Cor and Cor-C60. Spectroscopic, electrochemical, and DFT studies confirmed the molecular integrity and existence of a moderate level of intramolecular interactions between the components. Steady-state fluorescence studies showed efficient energy transfer from (1) TPA* to the corrole and subsequent electron transfer from (1) corrole* to fullerene. Further studies involving femtosecond and nanosecond laser flash photolysis confirmed electron transfer to be the quenching mechanism of corrole emission, in which the electron-transfer products, the corrole radical cation (Cor(⋅+) in Cor-C60 and TPA-Cor(⋅+) in TPACor-C60) and fullerene radical anion (C60(⋅-)), could be spectrally characterized. Owing to the close proximity of the donor and acceptor entities in the dyad and triad, the rate of charge separation, kCS , was found to be about 10(11)  s(-1), suggesting the occurrence of an ultrafast charge-separation process. Interestingly, although an order of magnitude slower than kCS , the rate of charge recombination, kCR , was also found to be rapid (kCR ≈10(10)  s(-1)), and both processes followed the solvent polarity trend DMF>benzonitrile>THF>toluene. The charge-separated species relaxed directly to the ground state in polar solvents while in toluene, formation of (3) corrole* was observed, thus implying that the energy of the charge-separated state in a nonpolar solvent is higher than the energy of (3) corrole* being about 1.52 eV. That is, ultrafast formation of a high-energy charge-separated state in toluene has been achieved in these closely spaced corrole

  16. Separation and recombinatiuon of charge carriers in solar cells with a nanostructured ZnO electrode; Trennung und Rekombination von Ladungstraegern in Solarzellen mit nanostrukturierter ZnO-Elektrode

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, Julian


    The publication investigates electrodes consisting of ZnO nanorods deposited hydrothermally on conductive glass substrate (conductive glass). The electrodes are transparent to visible light and are sensitized for solar cell applications by a light-absorbing layer which in this case consists either of organometallic dye molecules (N3) or of an indium sulfide layer with a thickness of only a few nanometers. Electric contacts for the sensitized electrode are either made of a liquid electrolyte or of a perforated solid electrolyte. Methods of analysis were impedance spectroscopy, time-resolved photocurrent measurements, and time-resolved microwave photoconductivity. A high concentration of up to 10{sup 20} was found in the ZnO nanorods. The dye-sensitized solar cell showed exessively fast recombination with the oxydized dye molecules (sub-{mu}s) but a slow recombination rate with the oxydized redox ions of the electrolyte (ms). In the indium sulfide solar cells, the charges are separated at the contact with the ZnO nanorods while contact with the perforated CuSCN conductor is not charge-separating. Recombination takes place in indium sulfide, directly between the perforated conductor and ZnO, and also via the charge-separating contact with decreasing rates.


    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Graham; Ahn, Tae Kyu; Avenson, Thomas J.; Ballottari, Matteo; Cheng, Yuan-Chung; Niyogi, Krishna K.; Bassi, Roberto; Fleming, Graham R.


    Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge-transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). In this work, we present evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a de-localized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can `tune? the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophylls-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.

  18. Coupling of electric charge and magnetic field via electronic phase separation in (La,Pr,Ca)MnO3/Pb(Mg1/3Nb2/3)O3-PbTiO3 multiferroic heterostructures (United States)

    Zheng, Ming; Wang, Wei


    The electric-field-tunable non-volatile resistivity and ferromagnetism switching in the (La0.5Pr0.5)0.67Ca0.33MnO3 films grown on (111)-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 ferroelectric single-crystal substrates have been investigated. By combining the 180° ferroelectric domain switching and in situ X-ray diffraction and resistivity measurements, we identify that this voltage control of order parameters stems from the domain switching-induced accumulation/depletion of charge carriers at the interface rather than induced lattice strain effect. In particular, the polarization-induced charge effect (i.e., ferroelectric field effect) is strongly dependent on the magnetic field. This, together with the charge-modulated magnetoresistance and magnetization, reveals the strong correlation between the electric charge and the magnetic field. Further, we found that this coupling is essentially driven by the electronic phase separation, the relative strength of which could be determined by recording charge-tunability of resistivity [ (Δρ/ρ)c h arg e ] under various magnetic fields. These findings present a potential strategy for elucidating essential physics of perovskite manganites and delivering prototype electronic devices for non-volatile information storage.

  19. Separation of 3′-sialyllactose and lactose by nanofiltration: A trade-off between charge repulsion and pore swelling induced by high pH

    DEFF Research Database (Denmark)

    Nordvang, Rune Thorbjørn; Luo, Jianquan; Zeuner, Birgitte


    not affect SL retention significantly. The expected increase in retention levels of SL at high pH - due to repulsion between the negative charge of the membrane and the charged SL - was apparently offset by pore swelling of the NF membranes at high pH. The water permeability was measured before and after...... a membrane was used for filtration of a mixture of lactose and SL. For the NP010 and DSS-ETNA membranes, the decline in water permeability was lower when the experiments were conducted at high pH, which is ascribed to the electrostatic repulsion of SL by the membrane. Further improvements in the ratio...

  20. Altered gene expression by sedaxane increases PSII efficiency, photosynthesis and growth and improves tolerance to drought in wheat seedlings. (United States)

    Ajigboye, Olubukola O; Lu, Chungui; Murchie, Erik H; Schlatter, Christian; Swart, Gina; Ray, Rumiana V


    Succinate dehydrogenase inhibitor (SDHI) fungicides have been shown to increase PSII efficiency and photosynthesis under drought stress in the absence of disease to enhance the biomass and yield of winter wheat. However, the molecular mechanism of improved photosynthetic efficiency observed in SDHI-treated wheat has not been previously elucidated. Here we used a combination of chlorophyll fluorescence, gas exchange and gene expression analysis, to aid our understanding of the basis of the physiological responses of wheat seedlings under drought conditions to sedaxane, a novel SDHI seed treatment. We show that sedaxane increased the efficiency of PSII photochemistry, reduced non-photochemical quenching and improved the photosynthesis and biomass in wheat correlating with systemic changes in the expression of genes involved in defense, chlorophyll synthesis and cell wall modification. We applied a coexpression network-based approach using differentially expressed genes of leaves, roots and pregerminated seeds from our wheat array datasets to identify the most important hub genes, with top ranked correlation (higher gene association value and z-score) involved in cell wall expansion and strengthening, wax and pigment biosynthesis and defense. The results indicate that sedaxane confers tolerant responses of wheat plants grown under drought conditions by redirecting metabolites from defense/stress responses towards growth and adaptive development. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Detection of herbicide effects on pigment composition and PSII photochemistry in Helianthus annuus by Raman spectroscopy and chlorophyll a fluorescence (United States)

    Vítek, Petr; Novotná, Kateřina; Hodaňová, Petra; Rapantová, Barbora; Klem, Karel


    The effects of herbicides from three mode-of-action groups - inhibitors of protoporphyrinogen oxidase (carfentrazone-ethyl), inhibitors of carotenoid biosynthesis (mesotrione, clomazone, and diflufenican), and inhibitors of acetolactate synthase (amidosulfuron) - were studied in sunflower plants (Helianthus annuus). Raman spectroscopy, chlorophyll fluorescence (ChlF) imaging, and UV screening of ChlF were combined to evaluate changes in pigment composition, photosystem II (PSII) photochemistry, and non-photochemical quenching in plant leaves 6 d after herbicide application. The Raman signals of phenolic compounds, carotenoids, and chlorophyll were evaluated and differences in their intensity ratios were observed. Strongly augmented relative content of phenolic compounds was observed in the case of amidosulfuron-treated plants, with a simultaneous decrease in the chlorophyll/carotenoid intensity ratio. The results were confirmed by in vivo measurement of flavonols using UV screening of ChlF. Herbicides from the group of carotenoid biosynthesis inhibitors significantly decreased both the maximum quantum efficiency of PSII and non-photochemical quenching as determined by ChlF. Resonance Raman imaging (mapping) data with high resolution (150,000-200,000 spectra) are presented, showing the distribution of carotenoids in H. annuus leaves treated by two of the herbicides acting as inhibitors of carotenoid biosynthesis (clomazone or diflufenican). Clear signs were observed that the treatment induced carotenoid depletion within sunflower leaves. The depletion spatial pattern registered differed depending on the type of herbicide applied.

  2. Silver and gold nanoparticle separation using asymmetrical flow-field flow fractionation: Influence of run conditions and of particle and membrane charges. (United States)

    Meisterjahn, Boris; Wagner, Stephan; von der Kammer, Frank; Hennecke, Dieter; Hofmann, Thilo


    Flow-Field Flow Fractionation (Flow-FFF), coupled with online detection systems is one of the most promising tools available for the separation and quantification of engineered nanoparticles (ENPs) in complex matrices. To correctly relate the retention of nanoparticles in the Flow-FFF-channel to the particle size, ideal separation conditions must be met. This requires optimization of the parameters that influence the separation behavior. The aim of this study was therefore to systematically investigate and evaluate the influence of parameters such as the carrier liquid, the cross flow, and the membrane material, on the separation behavior of two metallic ENPs. For this purpose the retention, recovery, and separation efficiency of sterically stabilized silver nanoparticles (AgNPs) and electrostatically stabilized gold nanoparticles (AuNPs), which represent two materials widely used in investigations on environmental fate and ecotoxicology, were investigated against a parameter matrix of three different cross-flow densities, four representative carrier solutions, and two membrane materials. The use of a complex mixture of buffers, ionic and non-ionic surfactants (FL-70 solution) together with a medium cross-flow density provided an acceptable compromise in peak quality and recovery for both types of ENPs. However, these separation conditions do not represent a perfect match for both particle types at the same time (maximized recovery at maximized retention). It could be shown that the behavior of particles within Flow-FFF channels cannot be predicted or explained purely in terms of electrostatic interactions. Particles were irreversibly lost under conditions where the measured zeta potentials suggested that there should have been sufficient electrostatic repulsion to ensure stabilization of the particles in the Flow-FFF channel resulting in good recoveries. The wide variations that we observed in ENP behavior under different conditions, together with the different

  3. Cyclic electron flow may provide some protection against PSII photoinhibition in rice (Oryza sativa L.) leaves under heat stress. (United States)

    Essemine, Jemaa; Xiao, Yi; Qu, Mingnan; Mi, Hualing; Zhu, Xin-Guang


    Previously we have shown that a quick down-regulation in PSI activity compares to that of PSII following short-term heat stress for two rice groups including C4023 and Q4149, studied herein. These accessions were identified to have different natural capacities in driving cyclic electron flow (CEF) around PSI; i.e., low CEF (lcef) and high CEF (hcef) for C4023 and Q4149, respectively. The aim of this study was to investigate whether these two lines have different mechanisms of protecting photosystem II from photodamage under heat stress. We observed a stepwise alteration in the shape of Chl a fluorescence induction (OJIP) with increasing temperature treatment. The effect of 44°C treatment on the damping in Chl a fluorescence was more pronounced in C4023 than in Q4149. Likewise, we noted a disruption in the I-step, a decline in the Fv due to a strong damping in the Fm, and a slight increase in the F0. Normalized data demonstrated that the I-step seems more susceptible to 44°C in C4023 than in Q4149. We also measured the redox states of plastocyanin (PC) and P700 by monitoring the transmission changes at 820nm (I820), and observed a disturbance in the oxidation/reduction kinetics of PC and P700. The decline in the amplitude of their oxidation was shown to be about 29% and 13% for C4023 and Q4149, respectively. The electropotential component (Δφ) of ms-DLE appeared more sensitive to temperature stress than the chemical component (ΔpH), and the impact of heat was more evident and drastic in C4023 than in Q4149. Under heat stress, we noticed a concomitant decline in the primary photochemistry of PSII as well as in both the membrane energization process and the lumen protonation for both accessions, and it is evident that heat affects these parameters more in C4023 than in Q4149. All these data suggest that higher CET can confer higher photoprotection to PSII in rice lines, which can be a desirable trait during rice breeding, especially in the context of a "warming

  4. Fabrication of Heterogeneous-Phase Solid-Solution Promoting Band Structure and Charge Separation for Enhancing Photocatalytic CO2Reduction: A Case of ZnXCa1-XIn2S4. (United States)

    Zeng, Chao; Huang, Hongwei; Zhang, Tierui; Dong, Fan; Zhang, Yihe; Hu, Yingmo


    Photocatalytic CO 2 reduction into solar fuels illustrates huge charm for simultaneously settling energy and environmental issues. The photoreduction ability of a semiconductor is closely correlated to its conduction band (CB) position. A homogeneous-phase solid-solution with the same crystal system always has a monotonously changed CB position, and the high CB level has to be sacrificed to achieve a benign photoabsorption. Herein, we report the fabrication of heterogeneous-phase solid-solution Zn X Ca 1-X In 2 S 4 between trigonal ZnIn 2 S 4 and cubic CaIn 2 S 4 . The Zn X Ca 1-X In 2 S 4 solid solutions with orderly tuned photoresponsive range from 540 to 640 nm present a more negative CB level and highly enhanced charge-separation efficiency. Profiting from these merits, all of these Zn X Ca 1-X In 2 S 4 solid solutions exhibit remarkably strengthened photocatalytic CO 2 reduction performance under visible light (λ > 420 nm) irradiation. Zn 0.4 Ca 0.6 In 2 S 4 , bearing the most negative CB position and highest charge-separation efficiency, casts the optimal photocatalytic CH 4 and CO evolution rates, which reach 16.7 and 6.8 times higher than that of ZnIn 2 S 4 and 7.2 and 3.9 times higher than that of CaIn 2 S 4 , respectively. To verify the crucial role of the heterogeneous-phase solid solution in promoting the band structure and photocatalytic performance, another heterogeneous-phase solid-solution Zn X Cd 1-X In 2 S 4 has been synthesized. It also displays an upshifted CB level and promoted charge separation. This work may provide a new perspective into the development of an efficient visible-light driven photocatalyst for CO 2 reduction and other photoreduction reactions.

  5. Data analysis to separate particles of different speed regimes and charges. [lunar ejecta and meteorite experiment and pioneer space probe data (United States)

    Wolf, H.


    Although the instruments on the lunar ejecta and meteorite experiment (LEAM) and the Pioneer 8 and 9 space probes were essentially similar, a comparison of their results indicates that different sets of particles caused the different responses. On Pioneer, the events were caused by the impact of cosmic dust, the so-called beta particles expelled from the vicinity of the sun by solar radiation pressure, augmented by extremely high energy but definitely identifiable interstellar grains. On the moon, the events were due to the impact of slowly moving, highly charged lunar dust being propelled electrostatically across the terminator. Both theoretical analysis and experimental testing confirming these conclusions are discussed.

  6. Microemulsion electrokinetic chromatography of drugs varying in charge and hydrophobicity : I. Impact of parameters on separation performance evaluated by multiple regression models

    NARCIS (Netherlands)

    Harang, Valérie; Eriksson, Jessica; Sänger-van de Griend, Cari E.; Jacobsson, Sven P.; Westerlund, Douglas

    The separation of anionic, cationic and neutral drugs in microemulsion electrokinetic chromatography (MEEKC) was studied with a statistical experimental design. The concentration of sodium dodecyl sulfate (SDS, surfactant), 1-butanol (co-surfactant) and borate buffer and the factors Brij 35

  7. High-Performance Liquid Chromatography of Nucleobases, Nucleosides and Nucleotides : II. Mobile Phase Composition for the Separation of Charged Solutes by Ion-Exchange Chromatography

    NARCIS (Netherlands)

    Haastert, Peter J.M. van


    The polarity, pH, ion concentration and polarity of the buffer ions of the mobile phase were modified systematically in order to find optimal conditions for the separation of nucleobases, nucleosides and nucleotides by ion-exchange chromatography. The effects of these mobile phase parameters on the

  8. Theoretical investigation of the possibility of isotope separation during motion of charged particles in the electromagnetic field of a cylindrical capacitor and a linear current flowing along its axis (United States)

    Kirochkin, Yu. A.; Kirochkin, A. Yu.


    A characteristic feature of the trajectories of charges moving in constant axisymmetric radial electric and azimuthal magnetic fields, whose strengths are inversely proportional to the center from the symmetry axis is the exponential dependence of the turning points on the parameters of motion. This leads to a noticeable difference in the trajectories for isotope ions, which makes it possible to obtain a new method for their electromagnetic separation. The trajectories of isotopes being separated are studied theoretically. The conditions under which the trajectories are closed and form toroidal surfaces (storage vortex rings) have been determined earlier. These results are given for convenience in analyzing another problem, associated with the formation of such ionic toroidal vortex surfaces (stable in Wood’s sense) during a streak lightning discharge in the atmosphere (ball lightning model).

  9. Broadband Light Absorption and Efficient Charge Separation Using a Light Scattering Layer with Mixed Cavities for High-Performance Perovskite Photovoltaic Cells with Stability. (United States)

    Moon, Byeong Cheul; Park, Jung Hyo; Lee, Dong Ki; Tsvetkov, Nikolai; Ock, Ilwoo; Choi, Kyung Min; Kang, Jeung Ku


    CH3 NH3 PbI3 is one of the promising light sensitizers for perovskite photovoltaic cells, but a thick layer is required to enhance light absorption in the long-wavelength regime ranging from PbI2 absorption edge (500 nm) to its optical band-gap edge (780 nm) in visible light. Meanwhile, the thick perovskite layer suppresses visible-light absorption in the short wavelengths below 500 nm and charge extraction capability of electron-hole pairs produced upon light absorption. Herein, we find that a new light scattering layer with the mixed cavities of sizes in 100 and 200 nm between transparent fluorine-doped tin oxide and mesoporous titanium dioxide electron transport layer enables full absorption of short-wavelength photons (λ cell with a light scattering layer of mixed cavities is stabilized due to suppressed charge accumulation. Consequently, this work provides a new route to realize broadband light harvesting of visible light for high-performance perovskite photovoltaic cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Assessment of charge-transfer excitations with time-dependent, range-separated density functional theory based on long-range MP2 and multiconfigurational self- consistent field wave functions

    DEFF Research Database (Denmark)

    Hedegård, Erik D.; Jensen, Hans Jørgen Aagaard; Knecht, Stefan


    Charge transfer excitations can be described within Time-Dependent Density Functional Theory (TD-DFT), not only by means of the Coulomb Attenuated Method (CAM) but also with a combination of wave function theory and TD-DFT based on range separation. The latter approach enables a rigorous formulat......Charge transfer excitations can be described within Time-Dependent Density Functional Theory (TD-DFT), not only by means of the Coulomb Attenuated Method (CAM) but also with a combination of wave function theory and TD-DFT based on range separation. The latter approach enables a rigorous...... formulation of multi-determinantal TD-DFT schemes where excitation classes, which are absent in conventional TD-DFT spectra (like for example double excitations), can be addressed. This paper investigates the combination of both the long-range Multi-Configuration Self-Consistent Field (MCSCF) and Second Order...... Polarization Propagator Approximation (SOPPA) ansätze with a short-range DFT (srDFT) description. We find that the combinations of SOPPA or MCSCF with TD-DFT yield better results than could be expected from the pure wave function schemes. For the Time-Dependent MCSCF short-range DFT ansatz (TD...

  11. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes. (United States)

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M


    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

  12. MoS2 quantum dots@TiO2 nanotube composites with enhanced photoexcited charge separation and high-efficiency visible-light driven photocatalysis. (United States)

    Zhao, Fenfen; Rong, Yuefei; Wan, Junmin; Hu, Zhiwen; Peng, Zhiqin; Wang, Bing


    MoS2 quantum dots (QDs) that are 5 nm in size were deposited on the surface of ultrathin TiO2 nanotubes (TNTs) with 5 nm wall thickness by using an improved hydrothermal method to form a MoS2 QDs@TNT visible-light photocatalyst. The ultrathin TNTs with high percentage of photocatalytic reactive facets were fabricated by the commercially available TiO2 nanoparticles (P25) through an improved hydrothermal method, and the MoS2 QDs were acquired by using a surfactant-assisted technique. The novel MoS2 QDs@TNT photocatalysts showed excellent photocatalytic activity with a decolorization rate of 92% or approximately 3.5 times more than that of pure TNTs for the high initial concentration of methylene blue solution (20 mg/L) within 40 min under visible-light irradiation. MoS2 as the co-catalysts favored the broadening of TNTs into the visible-light absorption scope. The quantum confinement and edge effects of the MoS2 QDs and the heterojunction formed between the MoS2 QDs and TNTs efficiently extended the lifetime of photoinduced charges, impeded the recombination of photoexcited electron-hole pairs, and improved the visible-light-driven high-efficiency photocatalysis. © 2018 IOP Publishing Ltd.

  13. Improved photo-induced charge carriers separation through the addition of erbium on TiO2 nanoparticles and its effect on photocatalytic degradation of rhodamine B (United States)

    Dhanalakshmi, J.; Celina Selvakumari, J.; Pathinettam Padiyan, D.


    ErxTi1 - xO2 nanocomposites was prepared by a simple sol-gel method with various proportion of erbium viz., x = 0.02, x = 0.04, x = 0.06, x = 0.08 and x = 0.10. The prepared nanocomposites were studied using XRD, UV-Vis DRS, Raman spectra, HR-SEM, EDS, TEM, PL and impedance spectroscopy. XRD revealed that modified TiO2 nanocomposites possessed only the anatase phase with crystallite sizes of about 8.1 to 12.7 nm and which is well consistent with TEM analysis. It is seen that erbium ion exist in the nanocomposites based on the analysis of EDS. HR-SEM analysis revealed that the ErxTi1 - xO2 nanocomposites are spherical in shape with size between 10 and 20 nm. The amount of erbium remarkably affects the structural, optical and electrical properties. Loading erbium could produce 4f energy levels between valence and conduction bands thus narrowing optical band gap and generates visible absorption peaks. It was found that erbium modified TiO2 nanocomposites induced a shift in Raman. The enhancement of life time of charge carriers was observed on erbium inclusion.

  14. Separate Colors, Separate Minds. (United States)

    Meyers, Michael; Nidiry, John P.


    Explains that racial separation causes cultural separation, and the way to improve race relations is to continue to move toward integration. Discusses the need to debunk race, examining racial issues in education. Highlights the importance of actively supporting integration and opposing separatism, explaining that for there to be social progress,…

  15. Merging Structural Information from X-ray Crystallography, Quantum Chemistry, and EXAFS Spectra: The Oxygen-Evolving Complex in PSII. (United States)

    Chernev, Petko; Zaharieva, Ivelina; Rossini, Emanuele; Galstyan, Artur; Dau, Holger; Knapp, Ernst-Walter


    Structural data of the oxygen-evolving complex (OEC) in photosystem II (PSII) determined by X-ray crystallography, quantum chemistry (QC), and extended X-ray absorption fine structure (EXAFS) analyses are presently inconsistent. Therefore, a detailed study of what information can be gained about the OEC through a comparison of QC and crystallographic structure information combined with the information from range-extended EXAFS spectra was undertaken. An analysis for determining the precision of the atomic coordinates of the OEC by QC is carried out. OEC model structures based on crystallographic data that are obtained by QC from different research groups are compared with one another and with structures obtained by high-resolution crystallography. The theory of EXAFS spectra is summarized, and the application of EXAFS spectra to the experimental determination of the structure of the OEC is detailed. We discriminate three types of parameters entering the formula for the EXAFS spectrum: (1) model-independent, predefined, and fixed; (2) model-dependent that can be computed or adjusted; and (3) model-dependent that must be adjusted. The information content of EXAFS spectra is estimated and is related to the precision of atomic coordinates and resolution power to discriminate different atom-pair distances of the OEC. It is demonstrated how a precise adjustment of atomic coordinates can yield a nearly perfect representation of the experimental OEC EXAFS spectrum, but at the expense of overfitting and losing the knowledge of the initial OEC model structure. Introducing a novel type of penalty function, it is shown that moderate adjustment of atomic coordinates to the EXAFS spectrum limited by constraints avoids overfitting and can be used to validate different OEC model structures. This technique is used to identify the OEC model structures whose computed OEC EXAFS spectra agree best with the measured spectrum. In this way, the most likely S-state and protonation pattern

  16. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ognibene, Theodore Joseph [Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.


    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31Cl, 27P and 28P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31Cl and 27P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31Cl were shown to be from the decay of 25Si. In 27P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17Ne and 33Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17Ne and 33Ar were resolved.

  17. Modelling the effects of PSII inhibitor pulse exposure on two algae in co-culture. (United States)

    Copin, Pierre-Jean; Chèvre, Nathalie


    A weakness of standard testing procedures is that they do not consider interactions between organisms, and they focus only on single species. Furthermore, these procedures do not take into account pulse exposure. However, pulse exposure is of particular importance because in streams, after crop application and during and after precipitation, herbicide concentrations fluctuate widely and can exceed the Annual Average Environmental Quality Standards (AA-EQS), which aim to protect the aquatic environment. The sensitivity of the algae Scenedesmus vacuolatus and Pseudokirchneriella subcapitata in a co-culture exposed to pulses is thus analysed in this study. As a first step, the growths of the algae in co-culture are investigated. For initial cell densities fixed, respectively, to 100,000 and 50,000 cells/mL, the growth of each alga is exponential over at least 48 h. S. vacuolatus seems to influence the growth of P. subcapitata negatively. Allelopathy is a possible explanation for this growth inhibition. The toxicity of the herbicide isoproturon is later tested on the algae S. vacuolatus and P. subcapitata cultured alone and in the co-culture. Despite the supplementary stress on the algae in the co-culture competing for nutrients, the toxicity of the herbicide is lower for the two algae when they are in the co-culture than when they are in separated culture. A model is adapted and used to predict the cell-density inhibition on the alga S. vacuolatus in the co-culture with the alga P. subcapitata exposed to a pulse concentration of isoproturon. Four laboratory experiments are performed to validate the model. The comparison between the laboratory and the modelled effects shows good agreement. The differences can be considered minor most of time. For future studies, it is important to ensure that the cell count is precise, as it is used to determine the parameters of the model. The differences can be also induced by the fact that the cell number of the alga P

  18. Photosystem II-cyclic electron flow powers exceptional photoprotection and record growth in the microalga Chlorella ohadii. (United States)

    Ananyev, Gennady; Gates, Colin; Kaplan, Aaron; Dismukes, G Charles


    The desert microalga Chlorella ohadii was reported to grow at extreme light intensities with minimal photoinhibition, tolerate frequent de/re-hydrations, yet minimally employs antenna-based non-photochemical quenching for photoprotection. Here we investigate the molecular mechanisms by measuring Photosystem II charge separation yield (chlorophyll variable fluorescence, Fv/Fm) and flash-induced O2 yield to measure the contributions from both linear (PSII-LEF) and cyclic (PSII-CEF) electron flow within PSII. Cells grow increasingly faster at higher light intensities (μE/m2/s) from low (20) to high (200) to extreme (2000) by escalating photoprotection via shifting from PSII-LEF to PSII-CEF. This shifts PSII charge separation from plastoquinone reduction (PSII-LEF) to plastoquinol oxidation (PSII-CEF), here postulated to enable proton gradient and ATP generation that powers photoprotection. Low light-grown cells have unusually small antennae (332 Chl/PSII), use mainly PSII-LEF (95%) and convert 40% of PSII charge separations into O2 (a high O2 quantum yield of 0.06mol/mol PSII/flash). High light-grown cells have smaller antenna and lower PSII-LEF (63%). Extreme light-grown cells have only 42 Chl/PSII (no LHCII antenna), minimal PSII-LEF (10%), and grow faster than any known phototroph (doubling time 1.3h). Adding a synthetic quinone in excess to supplement the PQ pool fully uncouples PSII-CEF from its natural regulation and produces maximum PSII-LEF. Upon dark adaptation PSII-LEF rapidly reverts to PSII-CEF, a transient protection mechanism to conserve water and minimize the cost of antenna biosynthesis. The capacity of the electron acceptor pool (plastoquinone pool), and the characteristic times for exchange of (PQH2)B with PQpool and reoxidation of (PQH2)pool were determined. Copyright © 2017. Published by Elsevier B.V.

  19. Relationships between PSII-independent hydrogen bioproduction and starch metabolism as evidenced from isolation of starch catabolism mutants in the green alga Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Chochois, Vincent; Constans, Laure; Beyly, Audrey; Soliveres, Melanie; Peltier, Gilles; Cournac, Laurent [CEA, DSV, IBEB, Laboratoire de Bioenergetique et Biotechnologie des Bacteries and Microalgues, Saint Paul Lez Durance, F-13108 (France); CNRS, UMR Biologie Vegetale and Microbiologie Environnementales, Saint Paul lez Durance, F-13108 (France); Aix-Marseille Universite, Saint Paul lez Durance, F-13108 (France); Dauvillee, David; Ball, Steven [Univ Lille Nord de France, F-59000 Lille (France); USTL, UGSF, F-59650 Villeneuve d' Ascq (France); CNRS, UMR 8576, F-59650 Villeneuve d' Ascq (France)


    Sulfur deprivation, which is considered as an efficient way to trigger long-term hydrogen photoproduction in unicellular green algae has two major effects: a decrease in PSII which allows anaerobiosis to be reached and carbohydrate (starch) storage. Starch metabolism has been proposed as one of the major factors of hydrogen production, particularly during the PSII-independent (or indirect) pathway. While starch biosynthesis has been characterized in the green alga Chlamydomonas reinhardtii, little remains known concerning starch degradation. In order to gain a better understanding of starch catabolism pathways and identify those steps likely to limit the starch-dependent hydrogen production, we have designed a genetic screening procedure aimed at isolating mutants of the green alga C. reinhardtii affected in starch mobilization. Using two different screening protocols, the first one based on aerobic starch degradation in the dark and the second one on anaerobic starch degradation in the light, eighteen mutants were isolated among a library of 15,000 insertion mutants, eight (std1-8) with the first screen and ten (sda1-10) with the second. Most of the mutant strains isolated in this study showed a reduction or a delay in the PSII-independent hydrogen production. Further characterization of these mutants should allow the identification of molecular determinants of starch-dependent hydrogen production and supply targets for future biotechnological improvements. (author)


    Energy Technology Data Exchange (ETDEWEB)

    Clarke, John


    The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

  1. Internal Charging (United States)

    Minow, Joseph I.


    (1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.

  2. C lostridium difficile surface proteins are anchored to the cell wall using CWB2 motifs that recognise the anionic polymer PSII (United States)

    Willing, Stephanie E.; Candela, Thomas; Shaw, Helen Alexandra; Seager, Zoe; Mesnage, Stéphane; Fagan, Robert P.


    Summary Gram‐positive surface proteins can be covalently or non‐covalently anchored to the cell wall and can impart important properties on the bacterium in respect of cell envelope organisation and interaction with the environment. We describe here a mechanism of protein anchoring involving tandem CWB2 motifs found in a large number of cell wall proteins in the Firmicutes. In the Clostridium difficile cell wall protein family, we show the three tandem repeats of the CWB2 motif are essential for correct anchoring to the cell wall. CWB2 repeats are non‐identical and cannot substitute for each other, as shown by the secretion into the culture supernatant of proteins containing variations in the patterns of repeats. A conserved Ile Leu Leu sequence within the CWB2 repeats is essential for correct anchoring, although a preceding proline residue is dispensable. We propose a likely genetic locus encoding synthesis of the anionic polymer PSII and, using RNA knock‐down of key genes, reveal subtle effects on cell wall composition. We show that the anionic polymer PSII binds two cell wall proteins, SlpA and Cwp2, and these interactions require the CWB2 repeats, defining a new mechanism of protein anchoring in Gram‐positive bacteria. PMID:25649385

  3. Separated Shoulder (United States)

    ... an injury to the ligaments that hold your collarbone (clavicle) to your shoulder blade. In a mild separated ... tenderness or pain near the end of your collarbone. Causes The most common cause of a separated ...

  4. Heterostructured WS2-MoS2Ultrathin Nanosheets Integrated on CdS Nanorods to Promote Charge Separation and Migration and Improve Solar-Driven Photocatalytic Hydrogen Evolution. (United States)

    Reddy, D Amaranatha; Park, Hanbit; Ma, Rory; Kumar, D Praveen; Lim, Manho; Kim, Tae Kyu


    Solar-driven photocatalytic hydrogen evolution is important to bring solar-energy-to-fuel energy-conversion processes to reality. However, there is a lack of highly efficient, stable, and non-precious photocatalysts, and catalysts not designed completely with expensive noble metals have remained elusive, which hampers their large-scale industrial application. Herein, for the first time, a highly efficient and stable noble-metal-free CdS/WS 2 -MoS 2 nanocomposite was designed through a facile hydrothermal approach. When assessed as a photocatalyst for water splitting, the CdS/WS 2 -MoS 2 nanostructures exhibited remarkable photocatalytic hydrogen-evolution performance and impressive durability. An excellent hydrogen evolution rate of 209.79 mmol g -1  h -1 was achieved under simulated sunlight irradiation, which is higher than the values for CdS/MoS 2 (123.31 mmol g -1  h -1 ) and CdS/WS 2 nanostructures (169.82 mmol g -1  h -1 ) and the expensive CdS/Pt benchmark catalyst (34.98 mmol g -1  h -1 ). The apparent quantum yield reached 51.4 % at λ=425 nm in 5 h. Furthermore, the obtained hydrogen evolution rate was better than those of several noble-metal-free catalysts reported previously. The observed high rate of hydrogen evolution and remarkable stability may be a result of the ultrafast separation of photogenerated charge carriers and transport between the CdS nanorods and the WS 2 -MoS 2 nanosheets, which thus increases the number of electrons involved in hydrogen production. The proposed designed strategy is believed to potentially open a door to the design of advanced noble-metal-free photocatalytic materials for efficient solar-driven hydrogen production. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Charge Breeding Techniques

    CERN Document Server

    Wenander, F


    The numerous newly built and forthcoming post-accelerators for radioactive ions, produced with the isotope separator on-line (ISOL) technique, all have a need for an efficient method to accelerate the precious primary ions. By increasing the ion charge-to-mass ratio directly after the radioactive ion production stage, a short and compact linear accelerator can be employed. Not only the efficiency, but also the rapidity of such a charge-to-mass increasing process, called charge breeding, is a crucial factor for the often short-lived radioisotopes. The traditional foil or gas stripping technique was challenged some five to ten years ago by novel schemes for charge breeding. The transformation from 1+ to n+ charged ions takes place inside an Electron Beam Ion Source/Trap (EBIS/T) or Electron Cyclotron Resonance Ion Source/Trap (ECRIS/T) by electron-ion collisions. These charge breeders are located in the low-energy part of the machine before the accelerating structures. Because of the capability of these devices...

  6. Separation techniques: Chromatography (United States)

    Coskun, Ozlem


    Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis. Proteins can be purified based on characteristics such as size and shape, total charge, hydrophobic groups present on the surface, and binding capacity with the stationary phase. Four separation techniques based on molecular characteristics and interaction type use mechanisms of ion exchange, surface adsorption, partition, and size exclusion. Other chromatography techniques are based on the stationary bed, including column, thin layer, and paper chromatography. Column chromatography is one of the most common methods of protein purification. PMID:28058406

  7. Influence of temperature on properties of nitrogen plasma source ion implantation (N-PSII) of Ti6A14V alloy

    CERN Document Server

    Geng Man; Zhao Qing


    Specimens of Ti6Al4V alloy were implanted with nitrogen plasma source ion implantation (N-PSII) at temperatures between 100 degree C and 600 degree C to a ion dose of 4 x 10 sup 1 sup 7 cm sup - sup 2. Auger Electron Spectroscopy (AES) was used to determine the nitrogen concentration depth profiles. Microhardness measurements and pin-on-disk wear test were performed to evaluate the improvements of the surface modification. Glancing angle X-ray diffraction (XRD) was employed to determine the phases presented in the surface modified layer. The thickness of implanted layer increased by about an order of magnitude when the temperature was elevated from 100 degree C to 600 degree C. Higher surface hardness and wear resistance was also obtained at higher temperature. Scanning electron microscopy (SEM) showed distinct microstructural changes and the presence of titanium nitrides in the implanted surface

  8. Estimating chlorophyll content and photochemical yield of photosystem II (ΦPSII) using solar-induced chlorophyll fluorescence measurements at different growing stages of attached leaves. (United States)

    Tubuxin, Bayaer; Rahimzadeh-Bajgiran, Parinaz; Ginnan, Yusaku; Hosoi, Fumiki; Omasa, Kenji


    This paper illustrates the possibility of measuring chlorophyll (Chl) content and Chl fluorescence parameters by the solar-induced Chl fluorescence (SIF) method using the Fraunhofer line depth (FLD) principle, and compares the results with the standard measurement methods. A high-spectral resolution HR2000+ and an ordinary USB4000 spectrometer were used to measure leaf reflectance under solar and artificial light, respectively, to estimate Chl fluorescence. Using leaves of Capsicum annuum cv. 'Sven' (paprika), the relationships between the Chl content and the steady-state Chl fluorescence near oxygen absorption bands of O2B (686nm) and O2A (760nm), measured under artificial and solar light at different growing stages of leaves, were evaluated. The Chl fluorescence yields of ΦF 686nm/ΦF 760nm ratios obtained from both methods correlated well with the Chl content (steady-state solar light: R(2) = 0.73; artificial light: R(2) = 0.94). The SIF method was less accurate for Chl content estimation when Chl content was high. The steady-state solar-induced Chl fluorescence yield ratio correlated very well with the artificial-light-induced one (R(2) = 0.84). A new methodology is then presented to estimate photochemical yield of photosystem II (ΦPSII) from the SIF measurements, which was verified against the standard Chl fluorescence measurement method (pulse-amplitude modulated method). The high coefficient of determination (R(2) = 0.74) between the ΦPSII of the two methods shows that photosynthesis process parameters can be successfully estimated using the presented methodology. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  9. Charge Breeding of Radioactive Ions

    CERN Document Server

    Wenander, F J C


    Charge breeding is a technique to increase the charge state of ions, in many cases radioactive ions. The singly charged radioactive ions, produced in an isotope separator on-line facility, and extracted with a low kinetic energy of some tens of keV, are injected into a charge breeder, where the charge state is increased to Q. The transformed ions are either directed towards a dedicated experiment requiring highly charged ions, or post-accelerated to higher beam energies. In this paper the physics processes involved in the production of highly charged ions will be introduced, and the injection and extraction beam parameters of the charge breeder defined. A description of the three main charge-breeding methods is given, namely: electron stripping in gas jet or foil; external ion injection into an electron-beam ion source/trap (EBIS/T); and external ion injection into an electron cyclotron resonance ion source (ECRIS). In addition, some preparatory devices for charge breeding and practical beam delivery aspects ...


    Skarstrom, C.


    A centrifugal separator is described for separating gaseous mixtures where the temperature gradients both longitudinally and radially of the centrifuge may be controlled effectively to produce a maximum separation of the process gases flowing through. Tbe invention provides for the balancing of increases and decreases in temperature in various zones of the centrifuge chamber as the result of compression and expansions respectively, of process gases and may be employed effectively both to neutralize harmful temperature gradients and to utilize beneficial temperaturc gradients within the centrifuge.

  11. Understanding the mechanism of enhanced charge separation and visible light photocatalytic activity of modified wurtzite ZnO with nanoclusters of ZnS and graphene oxide: from a hybrid density functional study

    CSIR Research Space (South Africa)

    Opoku, F


    Full Text Available A first principles study of the Titania is done as used in photo-catalysis to generate charge carries. Models of titania, silica, graphene, epoxy graphene monoxide, single wall Carbon nanotubes and their respective layer were studied in order...

  12. Ewald Electrostatics for Mixtures of Point and Continuous Line Charges. (United States)

    Antila, Hanne S; Tassel, Paul R Van; Sammalkorpi, Maria


    Many charged macro- or supramolecular systems, such as DNA, are approximately rod-shaped and, to the lowest order, may be treated as continuous line charges. However, the standard method used to calculate electrostatics in molecular simulation, the Ewald summation, is designed to treat systems of point charges. We extend the Ewald concept to a hybrid system containing both point charges and continuous line charges. We find the calculated force between a point charge and (i) a continuous line charge and (ii) a discrete line charge consisting of uniformly spaced point charges to be numerically equivalent when the separation greatly exceeds the discretization length. At shorter separations, discretization induces deviations in the force and energy, and point charge-point charge correlation effects. Because significant computational savings are also possible, the continuous line charge Ewald method presented here offers the possibility of accurate and efficient electrostatic calculations.

  13. Space charge

    CERN Document Server

    Schindl, Karlheinz


    The Coulomb forces between the charged particles of a high-intensity beam in an accelerator create a self-field which acts on the particles inside the beam like a distributed lens, defocusing in both transverse planes. A beam moving with speed n is accompanied by a magnetic field which partially cancels the electrostatic defocusing effect, with complete cancellation at c, the speed of light. The effect of this 'direct space charge' is evaluated for transport lines and synchrotrons where the number of betatron oscillations per machine turn, Q, is reduced by DQ. In a real accelerator, the beam is also influenced by the environment (beam pipe, magnets, etc.) which generates 'indirect' space charge effects. For a smooth and perfectly conducting wall, they can easily be evaluated by introducing image charges and currents. These 'image effects' do not cancel when n approaches c, thus they become dominant for high-energy synchrotrons. Each particle in the beam has its particular incoherent tune Q and incoherent tune...

  14. Arabidopsis plants lacking PsbQ and PsbR subunits of the oxygen-evolving complex show altered PSII super-complex organization and short-term adaptive mechanisms. (United States)

    Allahverdiyeva, Yagut; Suorsa, Marjaana; Rossi, Fabio; Pavesi, Andrea; Kater, Martin M; Antonacci, Alessia; Tadini, Luca; Pribil, Mathias; Schneider, Anja; Wanner, Gerhard; Leister, Dario; Aro, Eva-Mari; Barbato, Roberto; Pesaresi, Paolo


    The oxygen-evolving complex of eukaryotic photosystem II (PSII) consists of four extrinsic subunits, PsbO (33 kDa), PsbP (23 kDa), PsbQ (17 kDa) and PsbR (10 kDa), encoded by seven nuclear genes, PsbO1 (At5g66570), PsbO2 (At3g50820), PsbP1 (At1g06680), PsbP2 (At2g30790), PsbQ1 (At4g21280), PsbQ2 (At4g05180) and PsbR (At1g79040). Using Arabidopsis insertion mutant lines, we show that PsbP1, but not PsbP2, is essential for photoautotrophic growth, whereas plants lacking both forms of PsbQ and/or PsbR show normal growth rates. Complete elimination of PsbQ has a minor effect on PSII function, but plants lacking PsbR or both PsbR and PsbQ are characterized by more pronounced defects in PSII activity. Gene expression and immunoblot analyses indicate that accumulation of each of these proteins is highly dependent on the presence of the others, and is controlled at the post-transcriptional level, whereas PsbO stability appears to be less sensitive to depletion of other subunits of the oxygen-evolving complex. In addition, comparison of levels of the PSII super-complex in wild-type and mutant leaves reveals the importance of the individual subunits of the oxygen-evolving complex for the supramolecular organization of PSII and their influence on the rate of state transitions. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

  15. Isotope separation (United States)

    Bartlett, Rodney J.; Morrey, John R.


    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  16. ISOTOPE SEPARATORS (United States)

    Bacon, C.G.


    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  17. Comparison of modification strategies towards enhanced charge carrier separation and photocatalytic degradation activity of metal oxide semiconductors (TiO{sub 2}, WO{sub 3} and ZnO)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Girish [Department of Physics, Indian Institute of Science, Bengaluru, 560012 Karnataka (India); Department of Chemistry, School of Engineering and Technology, CMR University, Bengaluru, 562149, Karnataka (India); Rao, K.S.R. Koteswara, E-mail: [Department of Physics, Indian Institute of Science, Bengaluru, 560012 Karnataka (India)


    Graphical abstract: Semiconductor metal oxides: Modifications, charge carrier dynamics and photocatalysis. - Highlights: • TiO{sub 2}, WO{sub 3} and ZnO based photocatalysis is reviewed. • Advances to improve the efficiency are emphasized. • Differences and similarities in the modifications are highlighted. • Charge carrier dynamics for each strategy are discussed. - Abstract: Metal oxide semiconductors (TiO{sub 2}, WO{sub 3} and ZnO) finds unparalleled opportunity in wastewater purification under UV/visible light, largely encouraged by their divergent admirable features like stability, non-toxicity, ease of preparation, suitable band edge positions and facile generation of active oxygen species in the aqueous medium. However, the perennial failings of these photocatalysts emanates from the stumbling blocks like rapid charge carrier recombination and meager visible light response. In this review, tailoring the surface-bulk electronic structure through the calibrated and veritable approaches such as impurity doping, deposition with noble metals, sensitizing with other compounds (dyes, polymers, inorganic complexes and simple chelating ligands), hydrogenation process (annealing under hydrogen atmosphere), electronic integration with other semiconductors, modifying with carbon nanostructures, designing with exposed facets and tailoring with hierarchical morphologies to overcome their critical drawbacks are summarized. Taking into account the materials intrinsic properties, the pros and cons together with similarities and striking differences for each strategy in specific to TiO{sub 2}, WO{sub 3} & ZnO are highlighted. These subtlety enunciates the primacy for improving the structure-electronic properties of metal oxides and credence to its fore in the practical applications. Future research must focus on comparing the performances of ZnO, TiO{sub 2} and WO{sub 3} in parallel to get insight into their photocatalytic behaviors. Such comparisons not only reveal

  18. HRS Separator

    CERN Multimedia


    Footage of the 90 and 60 degree ISOLDE HRS separator magnets in the HRS separator zone. In the two vacuum sectors HRS20 and HRS30 equipment such as the HRS slits SL240, the HRS faraday cup FC300 and wiregrid WG210 can be spotted. Vacuum valves, turbo pumps, beamlines, quadrupoles, water and compressed air connections, DC and signal cabling can be seen throughout the video. The HRS main and user beamgate in the beamline between MAG90 and MAG60 and its switchboxes as well as all vacuum bellows and flanges are shown. Instrumentation such as the HRS scanner unit 482 / 483, the HRS WG470 wiregrid and slits piston can be seen. The different quadrupoles and supports are shown as well as the RILIS guidance tubes and installation at the magnets and the different radiation monitors.

  19. GPS Separator

    CERN Multimedia


    Footage of the 70 degree ISOLDE GPS separator magnet MAG70 as well as the switchyard for the Central Mass and GLM (GPS Low Mass) and GHM (GPS High Mass) beamlines in the GPS separator zone. In the GPS20 vacuum sector equipment such as the long GPS scanner 482 / 483 unit, faraday cup FC 490, vacuum valves and wiregrid piston WG210 and WG475 and radiation monitors can also be seen. Also the RILIS laser guidance and trajectory can be seen, the GPS main beamgate switch box and the actual GLM, GHM and Central Beamline beamgates in the beamlines as well as the first electrostatic quadrupoles for the GPS lines. Close up of the GHM deflector plates motor and connections and the inspection glass at the GHM side of the switchyard.

  20. Separation system (United States)

    Rubin, Leslie S.


    A separation system for dewatering radioactive waste materials includes a disposal container, drive structure for receiving the container, and means for releasably attaching the container to the drive structure. Separation structure disposed in the container adjacent the inner surface of the side wall structure retains solids while allowing passage of liquids. Inlet port structure in the container top wall is normally closed by first valve structure that is centrifugally actuated to open the inlet port and discharge port structure at the container periphery receives liquid that passes through the separation structure and is normally closed by second valve structure that is centrifugally actuated to open the discharge ports. The container also includes coupling structure for releasable engagement with the centrifugal drive structure. Centrifugal force produced when the container is driven in rotation by the drive structure opens the valve structures, and radioactive waste material introduced into the container through the open inlet port is dewatered, and the waste is compacted. The ports are automatically closed by the valves when the container drum is not subjected to centrifugal force such that containment effectiveness is enhanced and exposure of personnel to radioactive materials is minimized.

  1. Electrostatic free energy of weakly charged macromolecules in solution and intermacromolecular complexes consisting of oppositely charged polymers

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Cohen Stuart, M.A.


    When oppositely charged polyelectrolytes are mixed in water, attraction between oppositely charged groups may lead to the formation of polyelectrolyte complexes (associative phase separation, complex coacervation, interpolymer complexes). Theory is presented to describe the electrostatic free energy

  2. Correlated behavior of the EPR signal of cytochrome b-559 heme Fe(III) ligated by OH- and the multiline signal of the Mn cluster in PS-II membrane fragments. (United States)

    Fiege, R; Shuvalov, V A


    EPR signals of Cyt b-559 heme Fe(III) ligated by OH- and the multiline signal of the Mn cluster in PS-II membrane fragments have been investigated. In 2,3-dicyano-5,6-dichloro-p-benzoquinone-oxidized PS-II membrane fragments the light-induced decrease of the EPR signal of the heme Fe(III)-OH- is accompanied by the appearance of the EPR multiline signal of the Mn cluster. Addition of F- ions, which act as a stronger ligand for heme Fe(III) than OH-, decreases to the same extent the dark- and light-induced signal of the heme Fe(III)-OH- and the light-induced multiline signal of the Mn cluster. These results are discussed in terms of the light-induced formation of a bound OH' radical shared between the Cyt b-559 heme Fe and the Mn cluster as a first step of water oxidation.

  3. Improved UV-B screening capacity does not prevent negative effects of ambient UV irradiance on PSII performance in High Arctic plants. Results from a six year UV exclusion study

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.


    Long-term responses of ambient solar ultraviolet (UV) radiation were investigated on Salix arctica and Vaccinium uliginosum in a High Arctic heath ecosystem in Zackenberg, northeast Greenland. Over a period of six years, UV exclusion was conducted in the growing season by means of filters: 60% UV......-B reduction, 90% UV-B + UV-A reduction, UV transparent filter control, and an open control without filter. Plant responses were evaluated using specific leaf area, leaf content of UV-B absorbing compounds and PSII performance parameters derived from chlorophyll-a fluorescence induction curves. Based...... increased TRo/ABS = FV/FM and REo/ETo. These results demonstrate the current level of ambient UV-B to decrease PSII performance significantly in these High Arctic plants. It appears that the two plant species both have improved their UV-screening capacity, but through different strategies, although this did...

  4. Gas separating (United States)

    Gollan, A.


    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  5. Flow Separation (United States)


    perfomanoas que oette oirconstance peut entrainer, soit encore, d’un point de vue plus fondamental par la recherche dM phenomknas qui caracterisent 1M...dtfoolleoent, dont le m^canlsme de formation eat en tout point sen- blable h celui qui a etc döcrit § 2.2. XL se caracterise par la presence d’une onde...during orbital maneuvers with the Reaction Control System (RCS) and later plume induced separation leading to aerodynamic heating and control problems

  6. CHARGE Association

    Directory of Open Access Journals (Sweden)

    Semanti Chakraborty


    Full Text Available We present here a case of 17-year-old boy from Kolkata presenting with obesity, bilateral gynecomastia, mental retardation, and hypogonadotrophic hypogonadism. The patient weighed 70 kg and was of 153 cm height. Facial asymmetry (unilateral facial palsy, gynecomastia, decreased pubic and axillary hair, small penis, decreased right testicular volume, non-palpable left testis, and right-sided congenital inguinal hernia was present. The patient also had disc coloboma, convergent squint, microcornea, microphthalmia, pseudohypertelorism, low set ears, short neck, and choanalatresia. He had h/o VSD repaired with patch. Laboratory examination revealed haemoglobin 9.9 mg/dl, urea 24 mg/dl, creatinine 0.68 mg/dl. IGF1 77.80 ng/ml (decreased for age, GH <0.05 ng/ml, testosterone 0.25 ng/ml, FSH-0.95 ΅IU/ml, LH 0.60 ΅IU/ml. ACTH, 8:00 A.M cortisol, FT3, FT4, TSH, estradiol, DHEA-S, lipid profile, and LFT was within normal limits. Prolactin was elevated at 38.50 ng/ml. The patient′s karyotype was 46XY. Echocardiography revealed ventricularseptal defect closed with patch, grade 1 aortic regurgitation, and ejection fraction 67%. Ultrasound testis showed small right testis within scrotal sac and undescended left testis within left inguinal canal. CT scan paranasal sinuses revealed choanalatresia and deviation of nasal septum to the right. Sonomammography revealed bilateral proliferation of fibroglandular elements predominantly in subareoalar region of breasts. MRI of brain and pituitary region revealed markedly atrophic pituitary gland parenchyma with preserved infundibulum and hypothalamus and widened suprasellar cistern. The CHARGE association is an increasingly recognized non-random pattern of congenital anomalies comprising of coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or deafness. [1] These anomalies have a higher probability of occurring together. In this report, we have

  7. Rational and scalable fabrication of high-quality WO3/CdS core/shell nanowire arrays for photoanodes toward enhanced charge separation and transport under visible light. (United States)

    Li, Haijin; Zhou, Yong; Chen, Liang; Luo, Wenjun; Xu, Qinfeng; Wang, Xiaoyong; Xiao, Min; Zou, Zhigang


    High-quality one-dimensional WO3/CdS core/shell nanowire arrays used as photoanodes in photoelectrochemical (PEC) cells were for the first time prepared via a rational, two-step chemical vapor deposition process. The narrow band-gap CdS shell was homogeneously coated on the entire surface of as-grown WO3 core nanowire arrays, forming coaxial heterostructures. The one-dimensional core/shell heterostructure facilitates the photogenerated electron-hole pair separation and the electron transfer from CdS to WO3 nanowires under visible light illumination. Moreover, the core nanowire arrays provide a direct pathway for the electron transport. The present results imply that the WO3/CdS core/shell heterostructure nanowire arrays may be useful in the design of nanostructure photoanodes toward highly efficient PEC cells.

  8. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa. (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto


    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. "Batavia" (green) and cv. "Lollo Rossa" (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m(-2) s(-1) for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m(-2) s(-1) from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m(-2) s(-1) from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m(-2) s(-1) from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m(-2) s(-1) from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  9. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Directory of Open Access Journals (Sweden)

    Theoharis eOuzounis


    Full Text Available To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. ’Batavia’ (green and cv. ‘Lollo Rossa’ (red] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T lamps yielding 90 (±10 µmol m-2 s-1 for up to 20 hr, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED light treatments were Control (no blue addition, 1B 06-08 (Blue light at 45 µmol m-2 s-1 from 06:00 to 08:00, 1B 21-08 (Blue light at 45 µmol m-2 s-1 from 21:00 to 08:00, 2B 17-19 (Blue at 80 µmol m-2 s-1 from 17:00 to 19:00, and (1B 17-19 Blue at 45 µmol m-2 s-1from 17:00 to 19:00. Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  10. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto


    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. “Batavia” (green) and cv. “Lollo Rossa” (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m−2 s−1 for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m−2 s−1 from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m−2 s−1 from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m−2 s−1 from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m−2 s−1 from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent. PMID:25767473

  11. Rotatingwall Technique and Centrifugal Separation (United States)

    Anderegg, François

    This chapter describes the "rotating wall" technique which enables essentially unlimited confinement time of 109-1010 charged particles in a Penning trap. The applied rotating wall electric field provides a positive torque that counteracts background drags, resulting in radial compression or steady-state confinement in near-thermal equilibrium states. The last part of the chapter discusses centrifugal separation in a rotating multi-species non-neutral plasma. Separation occurs when the centrifugal energy is larger than the mixing due to thermal energy.


    Marshall, L.


    An apparatus and method are described for separating charged, high energy particles of equal momentum forming a beam where the particles differ slightly in masses. Magnetic lenses are utilized to focus the beam and maintain that condition while electrostatic fields located between magnetic lenses are utilized to cause transverse separation of the particles into two beams separated by a sufficient amount to permit an aperture to block one beam. (AEC)

  13. Paraxial charge compensator for electron cryomicroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Berriman, John A. [Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA (United Kingdom); Rosenthal, Peter B., E-mail: [Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA (United Kingdom)


    We describe a multi-hole condenser aperture for the production of several electron beams in the transmission electron microscope (TEM) making it possible to simultaneously image and irradiate spatially separated regions of a specimen. When the specimen is a thin film of vitreous ice suspended over a holey carbon film, simultaneous irradiation of the adjacent carbon support with the off-axis beam compensates for some of the effects of charging in the image formed by a beam irradiating only the ice. Because the intervening region is not irradiated, charge-neutralization of frozen-hydrated specimens can occur by a through-space mechanism such as the emission of secondary electrons from a grounded carbon support film. We use paraxial charge compensation (PCC) to control the amount of charge build-up on the specimen and observe the effects of charge on images. The multi-hole aperture thus provides a tool for investigating the mechanism of charging and charge mitigation during the imaging of radiation sensitive biological specimens by cryomicroscopy. -- Highlights: Black-Right-Pointing-Pointer A multi-hole condenser aperture produces multiple (paraxial) beams in TEM. Black-Right-Pointing-Pointer Paraxial charge compensation is used to study electron-optical effects of charging. Black-Right-Pointing-Pointer Emission of secondary electrons controls charging by a through space mechanism. Black-Right-Pointing-Pointer Paraxial beams compensate for charging effects in frozen-hydrated specimens.

  14. Workplace Charging. Charging Up University Campuses

    Energy Technology Data Exchange (ETDEWEB)

    Giles, Carrie [ICF International, Fairfax, VA (United States); Ryder, Carrie [ICF International, Fairfax, VA (United States); Lommele, Stephen [National Renewable Energy Lab. (NREL), Golden, CO (United States)


    This case study features the experiences of university partners in the U.S. Department of Energy's (DOE) Workplace Charging Challenge with the installation and management of plug-in electric vehicle (PEV) charging stations.

  15. When Charged Black Holes Merge (United States)

    Kohler, Susanna


    Most theoretical models assume that black holes arent charged. But a new study shows that mergers of charged black holes could explain a variety of astrophysical phenomena, from fast radio bursts to gamma-ray bursts.No HairThe black hole no hair theorem states that all black holes can be described by just three things: their mass, their spin, and their charge. Masses and spins have been observed and measured, but weve never measured the charge of a black hole and its widely believed that real black holes dont actually have any charge.That said, weve also never shown that black holes dont have charge, or set any upper limits on the charge that they might have. So lets suppose, for a moment, that its possible for a black hole to be charged. How might that affect what we know about the merger of two black holes? A recent theoretical study by Bing Zhang (University of Nevada, Las Vegas) examines this question.Intensity profile of a fast radio burst, a sudden burst of radio emission that lasts only a few milliseconds. [Swinburne Astronomy Productions]Driving TransientsZhangs work envisions a pair of black holes in a binary system. He argues that if just one of the black holes carries charge possibly retained by a rotating magnetosphere then it may be possible for the system to produce an electromagnetic signal that could accompany gravitational waves, such as a fast radio burst or a gamma-ray burst!In Zhangs model, the inspiral of the two black holes generates a global magnetic dipole thats perpendicular to the plane of the binarys orbit. The magnetic flux increases rapidly as the separation between the black holes decreases, generating an increasingly powerful magnetic wind. This wind, in turn, can give rise to a fast radio burst or a gamma-ray burst, depending on the value of the black holes charge.Artists illustration of a short gamma-ray burst, thought to be caused by the merger of two compact objects. [ESO/A. Roquette]Zhang calculates lower limits on the charge

  16. Development of an automatic scanning system for the detection of charged particles in Opera and pion/muon separation at low energies; Developpement d'un systeme de scan automatique pour la detection des particules chargees dans OPERA et separation des {pi}/{mu} de basse energie

    Energy Technology Data Exchange (ETDEWEB)

    Royole-Degieux, P


    The OPERA experiment (Oscillation Project with Emulsion t-Racking Apparatus) aims to check Super-Kamiokande results, searching for tau neutrinos apparition in an originally pure muon neutrino beam, by the direct observation of the tau decay topology. The OPERA target is made of walls of bricks, whose structure consists in a sandwich of lead plates and emulsion plates. The emulsions are very precise trajectographs ({approx} 1 micron) which will be used in a huge quantity during the experiment. Therefore, their analysis requires an automatic and dedicated acquisition system. First, this thesis aimed to tune and to develop the first French scanning system. The performances presented showed that the precision of the system respects the OPERA requirements and its speed is expected to increase in a few months. Then, the pion/muon separation at low energies was studies and test beams, designed to answer this problem, were performed. The firs results, showing the possibility of a separation, were presented. Finally, a reconstruction program dedicated to these stopping particles and taking into account the scanning efficiencies has been developed and tested. (author)

  17. Effects of acute O3 stress on PSII and PSI photochemistry of sensitive and resistant snap bean genotypes (Phaseolus vulgaris L.), probed by prompt chlorophyll "a" fluorescence and 820 nm modulated reflectance. (United States)

    Salvatori, Elisabetta; Fusaro, Lina; Strasser, Reto J; Bussotti, Filippo; Manes, Fausto


    The response of PSII and PSI photochemistry to acute ozone (O3) stress was tested in a "model plant system", namely the O3 sensitive (S156) and O3 resistant (R123) genotype pairs of Phaseolus vulgaris L., during a phenological phase of higher O3 sensitivity (pod formation). The modulation of the photosynthetic activity during O3 stress was analysed by measuring gas exchanges, Prompt Fluorescence (PF, JIP-test) and 820 nm Modulated Reflectance (MR), a novel techniques which specifically detects the changes in the redox state of P700 and plastocyanin. The results showed that, coherently with genotypic-specific O3 sensitivity, the response of the two snap bean genotypes differed for the intensity and time of onset of the considered physiological changes. In fact, despite leaf injury and gas exchanges reduction appeared concurrently in both genotypes, S156 showed a PSII down regulation already after the first day of fumigation (DOF), and an enhancement of Cyclic Electron Flow of PSI after the second DOF, whereas R123 showed only slight adjustments until the third DOF, when the activity of both photosystems was down-regulated. Despite these differences, it is possible to distinguish in both genotypes an early O3 response of the photochemical apparatus, involving PSII only, and a following response, in which PSI activity and content are also modulated. The measurement of the MR signal, performed simultaneously with the PF measurements and the JIP-test analysis, has allowed a better understanding of the role that PSI plays in the O3 stress response of the S156/R123 model plant system. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. Charge transfer reactions in nematic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wiederrecht, G.P. [Argonne National Lab., IL (United States). Chemistry Div.; Wasielewski, M.R. [Argonne National Lab., IL (United States). Chemistry Div.]|[Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Galili, T.; Levanon, H. [Hebrew Univ. of Jerusalem (Israel). Dept. of Physical Chemistry


    Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.

  19. Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae

    Directory of Open Access Journals (Sweden)

    Bascuñán-Godoy Luisa


    Full Text Available Abstract Background Ecotypes of Colobanthus quitensis Kunt Bartl (Cariophyllaceae from Andes Mountains and Maritime Antarctic grow under contrasting photoinhibitory conditions, reaching differential cold tolerance upon cold acclimation. Photoinhibition depends on the extent of photodamage and recovery capability. We propose that cold acclimation increases resistance to low-temperature-induced photoinhibition, limiting photodamage and promoting recovery under cold. Therefore, the Antarctic ecotype (cold hardiest should be less photoinhibited and have better recovery from low-temperature-induced photoinhibition than the Andean ecotype. Both ecotypes were exposed to cold induced photoinhibitory treatment (PhT. Photoinhibition and recovery of photosystem II (PSII was followed by fluorescence, CO2 exchange, and immunoblotting analyses. Results The same reduction (25% in maximum PSII efficiency (Fv/Fm was observed in both cold-acclimated (CA and non-acclimated (NA plants under PhT. A full recovery was observed in CA plants of both ecotypes under dark conditions, but CA Antarctic plants recover faster than the Andean ecotype. Under PhT, CA plants maintain their quantum yield of PSII, while NA plants reduced it strongly (50% and 73% for Andean and Antarctic plants respectively. Cold acclimation induced the maintenance of PsaA and Cyt b6/f and reduced a 41% the excitation pressure in Antarctic plants, exhibiting the lowest level under PhT. xCold acclimation decreased significantly NPQs in both ecotypes, and reduced chlorophylls and D1 degradation in Andean plants under PhT. NA and CA plants were able to fully restore their normal photosynthesis, while CA Antarctic plants reached 50% higher photosynthetic rates after recovery, which was associated to electron fluxes maintenance under photoinhibitory conditions. Conclusions Cold acclimation has a greater importance on the recovery process than on limiting photodamage. Cold acclimation determined the

  20. The net charge at interfaces between insulators (United States)

    Bristowe, N. C.; Littlewood, P. B.; Artacho, Emilio


    The issue of the net charge at insulating oxide interfaces is briefly reviewed with the ambition of dispelling myths of such charges being affected by covalency and related charge density effects. For electrostatic analysis purposes, the net charge at such interfaces is defined by the counting of discrete electrons and core ion charges, and by the definition of the reference polarization of the separate, unperturbed bulk materials. The arguments are illustrated for the case of a thin film of LaAlO3 over SrTiO3 in the absence of free carriers, for which the net charge is exactly 0.5e per interface formula unit, if the polarization response in both materials is referred to zero bulk values. Further consequences of the argument are extracted for structural and chemical alterations of such interfaces, in which internal rearrangements are distinguished from extrinsic alterations (changes of stoichiometry, redox processes), only the latter affecting the interfacial net charge. The arguments are reviewed alongside the proposal of Stengel and Vanderbilt (2009 Phys. Rev. B 80 241103) of using formal polarization values instead of net interfacial charges, based on the interface theorem of Vanderbilt and King-Smith (1993 Phys. Rev. B 48 4442-55). Implications for non-centrosymmetric materials are discussed, as well as for interfaces for which the charge mismatch is an integer number of polarization quanta.

  1. The net charge at interfaces between insulators

    Energy Technology Data Exchange (ETDEWEB)

    Bristowe, N C; Littlewood, P B [Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Artacho, Emilio, E-mail: [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom)


    The issue of the net charge at insulating oxide interfaces is briefly reviewed with the ambition of dispelling myths of such charges being affected by covalency and related charge density effects. For electrostatic analysis purposes, the net charge at such interfaces is defined by the counting of discrete electrons and core ion charges, and by the definition of the reference polarization of the separate, unperturbed bulk materials. The arguments are illustrated for the case of a thin film of LaAlO{sub 3} over SrTiO{sub 3} in the absence of free carriers, for which the net charge is exactly 0.5e per interface formula unit, if the polarization response in both materials is referred to zero bulk values. Further consequences of the argument are extracted for structural and chemical alterations of such interfaces, in which internal rearrangements are distinguished from extrinsic alterations (changes of stoichiometry, redox processes), only the latter affecting the interfacial net charge. The arguments are reviewed alongside the proposal of Stengel and Vanderbilt (2009 Phys. Rev. B 80 241103) of using formal polarization values instead of net interfacial charges, based on the interface theorem of Vanderbilt and King-Smith (1993 Phys. Rev. B 48 4442-55). Implications for non-centrosymmetric materials are discussed, as well as for interfaces for which the charge mismatch is an integer number of polarization quanta. (viewpoint)

  2. Distributed decay kinetics of charge separated state in solid film

    NARCIS (Netherlands)

    Lehtivuori, Heli; Efimov, Alexander; Lemmetyinen, Helge; Tkachenko, Nikolai V.


    Photoinduced electron transfer in solid films of porphyrin-fullerene dyads was studied using femtosecond pump-probe method. The relaxation of the main photo-product, intramolecular exciplex, was found to be essentially non-exponential. To analyze the decays a model accounting for a distribution of

  3. Charge separation and (triplet) recombination in diketopyrrolopyrrole-fullerene triads

    NARCIS (Netherlands)

    Karsten, Bram P.; Bouwer, Ricardo K. M.; Hummelen, Jan C.; Williams, Rene M.; Janssen, Rene A. J.


    Synthesis and photophysics of two diketopyrrolopyrrole-based small band gap oligomers, end-capped at both ends with C(60) are presented. Upon photoexcitation of the oligomer, ultrafast energy transfer to the fullerene occurs (similar to 0.5 ps), followed by an electron transfer reaction. Femtosecond

  4. Laser-induced charge separation in organic nanofibers

    DEFF Research Database (Denmark)

    Tavares, Luciana; Behn, Dino; Kjelstrup-Hansen, Jakob

    with the transport characteristics that show these nanofibers form p-type FET devices. Our current efforts are focused on nanofiber-based transistor devices using scanning photocurrent imaging (SPI) to study the local electronic band structure along the channel and at the contacts.......-assemble into crystalline nanofibers by vapor deposition onto muscovite mica substrates, and we have recently shown that such nanofibers can be transferred to different substrates by roll-printing and used as the active material in e.g. organic field-effect transistors (OFETs), organic light-emitting transistors (OLETs...


    Directory of Open Access Journals (Sweden)

    Vječislav Bohanek


    Full Text Available Shaped explosive charges with one dimension significantly larger than the other are called linear shaped charges. Linear shaped charges are used in various industries and are applied within specific technologies for metal cutting, such as demolition of steel structures, separating spent rocket fuel tanks, demining, cutting holes in the barriers for fire service, etc. According to existing theories and models efficiency of linear shaped charges depends on the kinetic energy of the jet which is proportional to square of jet velocity. The original method for measuring velocity of linear shaped charge jet is applied in the aforementioned research. Measurements were carried out for two different linear materials, and the results are graphically presented, analysed and compared. Measurement results show a discrepancy in the measured velocity of the jet for different materials with the same ratio between linear and explosive mass (M/C per unit of surface, which is not described by presented models (the paper is published in Croatian.

  6. Quantum mechanics of charged particle beam optics

    CERN Document Server

    Khan, Sameen Ahmed


    Theory of charged particle beam optics is basic to the design and working of charged particle beam devices from electron microscopes to accelerator machines. Traditionally, the optical elements of the devices are designed and operated based on classical mechanics and classical electromagnetism, and only certain specific quantum mechanical aspects are dealt with separately using quantum theory. This book provides a systematic approach to quantum theory of charged particle beam optics, particularly in the high energy cases such as accelerators or high energy electron microscopy.

  7. Screening effect on nanostructure of charged gel

    DEFF Research Database (Denmark)

    Sugiyama, M; Annaka, M; Hino, M


    Charge screening effects on nanostructures of N-isopropylacrylamide-sodium acrylate (NIPA-SA) and -acrylic acid (NIPA-AAc) gels are investigated with small-angle neutron scattering. The NIPA-SA and NIPA-AAc gels with low water content exhibit microphase separations with different dimensions....... The dehydrated NIPA-SA gel also makes the microphase separation but the dehydrated NIPA-AAc gel does not. These results indicate that ionic circumstance around charged bases strongly affects the nanostructures both of the dehydrated gel and the gel with low water content. (C) 2004 Elsevier B. V. All rights...

  8. Electrolytic cell. [For separating anolyte and catholyte (United States)

    Bullock, J.S.; Hale, B.D.


    An apparatus is described for the separation of the anolyte and the catholyte during electrolysis. The electrolyte flows through an electrolytic cell between the oppositely charged electrodes. The cell is equipped with a wedge-shaped device, the tapered end being located between the electrodes on the effluent side of the cell. The wedge diverts the flow of the electrolyte to either side of the wedge, substantially separating the anolyte and the catholyte.

  9. Magnetic Separator Enhances Treatment Possibilities (United States)


    Since the earliest missions in space, NASA specialists have performed experiments in low gravity. Protein crystal growth, cell and tissue cultures, and separation technologies such as electrophoresis and magnetophoresis have been studied on Apollo 14, Apollo 16, STS-107, and many other missions. Electrophoresis and magnetophoresis, respectively, are processes that separate substances based on the electrical charge and magnetic field of a molecule or particle. Electrophoresis has been studied on over a dozen space shuttle flights, leading to developments in electrokinetics, which analyzes the effects of electric fields on mass transport (atoms, molecules, and particles) in fluids. Further studies in microgravity will continue to improve these techniques, which researchers use to extract cells for various medical treatments and research.

  10. Charged Domain Walls


    Campanelli, L.; Cea, P.; Fogli, G. L.; Tedesco, L.


    In this paper we investigate Charged Domain Walls (CDW's), topological defects that acquire surface charge density $Q$ induced by fermion states localized on the walls. The presence of an electric and magnetic field on the walls is also discussed. We find a relation in which the value of the surface charge density $Q$ is connected with the existence of such topological defects.

  11. Fictional Separation Logic

    DEFF Research Database (Denmark)

    Jensen, Jonas Buhrkal; Birkedal, Lars


    , separation means physical separation. In this paper, we introduce \\emph{fictional separation logic}, which includes more general forms of fictional separating conjunctions P * Q, where "*" does not require physical separation, but may also be used in situations where the memory resources described by P and Q...... overlap. We demonstrate, via a range of examples, how fictional separation logic can be used to reason locally and modularly about mutable abstract data types, possibly implemented using sophisticated sharing. Fictional separation logic is defined on top of standard separation logic, and both the meta...

  12. Separating biological cells (United States)

    Brooks, D. E.


    Technique utilizing electric field to promote biological cell separation from suspending medium in zero gravity increases speed, reduces sedimentation, and improves efficiency of separation in normal gravity.

  13. Space Charge Effects

    CERN Document Server

    Ferrario, M.; Palumbo, L.


    The space charge forces are those generated directly by the charge distribution, with the inclusion of the image charges and currents due to the interaction of the beam with a perfectly conducting smooth pipe. Space charge forces are responsible for several unwanted phenomena related to beam dynamics, such as energy loss, shift of the synchronous phase and frequency , shift of the betatron frequencies, and instabilities. We will discuss in this lecture the main feature of space charge effects in high-energy storage rings as well as in low-energy linacs and transport lines.

  14. Electrodynamics of Radiating Charges

    Directory of Open Access Journals (Sweden)

    Øyvind Grøn


    Full Text Available The theory of electrodynamics of radiating charges is reviewed with special emphasis on the role of the Schott energy for the conservation of energy for a charge and its electromagnetic field. It is made clear that the existence of radiation from a charge is not invariant against a transformation between two reference frames that has an accelerated motion relative to each other. The questions whether the existence of radiation from a uniformly accelerated charge with vanishing radiation reaction force is in conflict with the principle of equivalence and whether a freely falling charge radiates are reviewed. It is shown that the resolution of an electromagnetic “perpetuum mobile paradox” associated with a charge moving geodetically along a circular path in the Schwarzschild spacetime requires the so-called tail terms in the equation of motion of a charged particle.

  15. Charging of highly resistive granular metal films (United States)

    Orihuela, M. F.; Ortuño, M.; Somoza, A. M.; Colchero, J.; Palacios-Lidón, E.; Grenet, T.; Delahaye, J.


    We have used the scanning Kelvin probe microscopy technique to monitor the charging process of highly resistive granular thin films. The sample is connected to two leads and is separated by an insulator layer from a gate electrode. When a gate voltage is applied, charges enter from the leads and rearrange across the sample. We find very slow processes with characteristic charging times exponentially distributed over a wide range of values, resulting in a logarithmic relaxation to equilibrium. After the gate voltage has been switched off, the system again relaxes logarithmically slowly to the new equilibrium. The results cannot be explained with diffusion models, but most of them can be understood with a hopping percolation model, in which the localization length is shorter than the typical site separation. The technique is very promising for the study of slow phenomena in highly resistive systems and will be able to estimate the conductance of these systems when direct macroscopic measurement techniques are not sensitive enough.

  16. Controlling Separation in Turbomachines (United States)

    Evans, Simon; Himmel, Christoph; Power, Bronwyn; Wakelam, Christian; Xu, Liping; Hynes, Tom; Hodson, Howard


    Four examples of flow control: 1) Passive control of LP turbine blades (Laminar separation control). 2) Aspiration of a conventional axial compressor blade (Turbulent separation control). 3) Compressor blade designed for aspiration (Turbulent separation control). 4.Control of intakes in crosswinds (Turbulent separation control).

  17. Separation/preconcentration of ultra-trace levels of inorganic Sb and Se from different sample matrices by charge transfer sensitized ion-pairing using ultrasonic-assisted cloud point extraction prior to their speciation and determination by hydride generation AAS. (United States)

    Altunay, Nail; Gürkan, Ramazan


    In the existing study, a new, simple and low cost process for separation/preconcentration of ultra-trace level of inorganic Sb and Se from natural waters, beverages and foods using ultrasonic-assisted cloud point extraction (UA-CPE) prior to their speciation and determination by hydride generation AAS, is proposed. The process is based on charge transfer sensitized complex formations of Sb(III) and Se(IV) with 3-amino-7-dimethylamino-2-methylphenazine hydrochloride (Neutral red, NRH(+)) in presence of pyrogallol and cetyltrimethylammonium bromide (CTAB) as both sensitivity enhancement and counter ion at pH 6.0. Under the optimized reagent conditions, the calibration curves were highly linear in the ranges of 8-300ngL(-1) and 12-250ngL(-1) (r(2)≥0.993) for Se(IV) and Sb(III), respectively. The limits of detection were 2.45 and 3.60ngL(-1) with sensitivity enhancement factors of 155 and 120, respectively. The recovery rate was higher than 96% with a relative standard deviation lower than 5.3% for five replicate measurements of 25, 75 and 150ngL(-1) Se(IV) and Sb(III), respectively. The method was validated by analysis of two certified reference materials (CRMs), and was successfully applied to the accurate and reliable speciation and determination of the contents of total Sb/Sb(III), and total Se/Se(IV) after UA-CPE of the pretreated sample matrices with and without pre-reduction with a mixture of l-cysteine and tartaric acid. Their Sb(V) and Se(VI) contents were calculated from the differences between total Sb and Sb(III) and/or total Se and Se(IV) levels. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Paraxial charge compensator for electron cryomicroscopy. (United States)

    Berriman, John A; Rosenthal, Peter B


    We describe a multi-hole condenser aperture for the production of several electron beams in the transmission electron microscope (TEM) making it possible to simultaneously image and irradiate spatially separated regions of a specimen. When the specimen is a thin film of vitreous ice suspended over a holey carbon film, simultaneous irradiation of the adjacent carbon support with the off-axis beam compensates for some of the effects of charging in the image formed by a beam irradiating only the ice. Because the intervening region is not irradiated, charge-neutralization of frozen-hydrated specimens can occur by a through-space mechanism such as the emission of secondary electrons from a grounded carbon support film. We use paraxial charge compensation (PCC) to control the amount of charge build-up on the specimen and observe the effects of charge on images. The multi-hole aperture thus provides a tool for investigating the mechanism of charging and charge mitigation during the imaging of radiation sensitive biological specimens by cryomicroscopy. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Charged slurry droplet research (United States)

    Kelly, A. J.


    Rayleigh Bursting, wherein critically charged droplets explosively expel a number of micron sized sibling droplets, enhances atomization and combustion of all liquid fuels. Droplet surface charge is retained during evaporation, permitting multiple Rayleigh Bursts to occur. Moreover, the charge is available for the deagglomeration of residual particulate flocs from slurry droplet evaporation. To fill gaps in our knowledge of these processes, an experimental program involving the use of a charged droplet levitator and a Quadrupole Mass Spectrometer, High Speed Electrometer (QMS/HSE) has been undertaken to observe the disruption and to measure quantitatively the debris. A charged droplet levitator based on a new video frame grabber technology to image transient events, is described. Sibling droplet size is ten microns or less and is close to, if not coincident with, the predicted phase transition in droplet charging level. The research effort has focused on the exploration of this transition and its implications.

  20. Trapping a Charged Atom

    Energy Technology Data Exchange (ETDEWEB)

    Hla, Saw-Wai [Center for Nanoscale Materials, Nanoscience and Technology Division, Argonne National Laboratory, Lemont, Illinois 60439, United States; Nanoscience and Quantum Phenomena Institute and Condensed Matter and Surface Science Program, Ohio University, Athens, Ohio 45701, United States


    Engineering of supramolecular assemblies on surfaces is an emerging field of research impacting chemistry, electronics, and biology. Among supramolecular assemblies, metal-containing structures provide rich properties and enable robust nanostructured designs. In this issue of ACS Nano, Feng eta!, report that supramolecular assemblies can trap gold adatoms that maintain a charged state on a Au(111) surface. Such charged adatoms may offer additional degrees of freedom in designing novel supramolecular architectures for efficient catalysts, memory, and charge storage for medical applications.

  1. Contractor Software Charges

    National Research Council Canada - National Science Library

    Granetto, Paul


    .... Examples of computer software costs that contractors charge through indirect rates are material management systems, security systems, labor accounting systems, and computer-aided design and manufacturing...

  2. The possibility of separation of electronic waste by means of their electrical properties

    Directory of Open Access Journals (Sweden)

    Skowron Mikolaj


    Full Text Available Electric field has a lot of applications in technology. One of them is electrodynamic separation: electric field influences selectively granular solids of different moments or charges. A mathematical model of the separation process in high voltage drum separator is presented in the paper. Particles are charged both by induction and corona phenomena: next, they are separated by effects of the field forces. Some computational and experimental results are given and analyses.

  3. Surface Charging and Points of Zero Charge

    CERN Document Server

    Kosmulski, Marek


    Presents Points of Zero Charge data on well-defined specimen of materials sorted by trademark, manufacturer, and location. This text emphasizes the comparison between particular results obtained for different portions of the same or very similar material and synthesizes the information published in research reports over the past few decades

  4. Effect of Charge Patterning on the Phase Behavior of Polymer Coacervates for Charge Driven Self Assembly (United States)

    Radhakrishna, Mithun; Sing, Charles E.

    Oppositely charged polymers can undergo associative liquid-liquid phase separation when mixed under suitable conditions of ionic strength, temperature and pH to form what are known as `polymeric complex coacervates'. Polymer coacervates find use in diverse array of applications like microencapsulation, drug delivery, membrane filtration and underwater adhesives. The similarity between complex coacervate environments and those in biological systems has also found relevance in areas of bio-mimicry. Our previous works have demonstrated how local charge correlations and molecular connectivity can drastically affect the phase behavior of coacervates. The precise location of charges along the chain therefore dramatically influences the local charge correlations, which consequently influences the phase behavior of coacervates. We investigate the effect of charge patterning along the polymer chain on the phase behavior of coacervates in the framework of the Restricted Primitive Model using Gibbs Ensemble Monte Carlo simulations. Our results show that charge patterning dramatically changes the phase behavior of polymer coacervates, which contrasts with the predictions of the classical Voorn-Overbeek theory. This provides the basis for designing new materials through charge driven self assembly by controlling the positioning of the charged monomers along the chain.

  5. Magnetic separation of algae (United States)

    Nath, Pulak; Twary, Scott N.


    Described herein are methods and systems for harvesting, collecting, separating and/or dewatering algae using iron based salts combined with a magnetic field gradient to separate algae from an aqueous solution.

  6. Separation anxiety in children (United States)

    ... page: // Separation anxiety in children To use the sharing features on this page, please enable JavaScript. Separation anxiety in children is a developmental stage in which ...

  7. Separators for electrochemical cells

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Steven Allen; Anakor, Ifenna Kingsley; Farrell, Greg Robert


    Provided are separators for use in an electrochemical cell comprising (a) an inorganic oxide and (b) an organic polymer, wherein the inorganic oxide comprises organic substituents. Also provided are electrochemical cells comprising such separators.

  8. Charged weak currents

    CERN Document Server

    Turlay, René


    In this review of charged weak currents the author concentrates on inclusive high energy neutrino physics. The authors discusses the general structure of charged currents, new results on total cross- sections, the Callan-Gross relation, antiquark distributions, scaling violations and tests of QCD. A very short summary on multilepton physics is given. (44 refs).

  9. Benchmarking charging infrastructure utilization

    NARCIS (Netherlands)

    Wolbertus, R.; van den Hoed, R.; Maase, S.


    Since 2012 the dutch metropolitan area (the metropole region of amsterdam, the city of amsterdam, rotterdam, the hague, utrecht ) cooperate in finding the best way to stimulate electric mobility through the implementation of a public charging infrastructure. with more than 5600 charge points and 1.6

  10. Using Ion Exchange Chromatography to Separate and Quantify Complex Ions (United States)

    Johnson, Brian J.


    Ion exchange chromatography is an important technique in the separation of charged species, particularly in biological, inorganic, and environmental samples. In this experiment, students are supplied with a mixture of two substitution-inert complex ions. They separate the complexes by ion exchange chromatography using a "flash"…

  11. Mechanisms controlling retention during ultrafiltration of charged saccharides: Molecular conformation and electrostatic forces

    DEFF Research Database (Denmark)

    Pinelo, Manuel; Møller, Victor; Prado-Rubio, Oscar A.


    Separation of different biomass components in solution, including charged saccharides, is one of the key challenges in biorefining of plant biomass. Ultrafiltration is one of the potential processes that could cope with such separation. Electrostatic interactions between solute molecules and betw......Separation of different biomass components in solution, including charged saccharides, is one of the key challenges in biorefining of plant biomass. Ultrafiltration is one of the potential processes that could cope with such separation. Electrostatic interactions between solute molecules...

  12. Induced Charge Capacitive Deionization

    CERN Document Server

    Rubin, S; Biesheuvel, P M; Bercovici, M


    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, which leads to rapid and significant deionization of ionic species from a volume which is on the scale of the particle. We show by theory and experiment that the transient response around a cylindrical particle results in spatially non-uniform charging and non-steady growth of depletion regions which emerge around the particle's poles. Potentially, ICCDI can be useful in applications where fast concentration changes of ionic species are required over large volumes.

  13. Electric vehicle battery charging controller


    Pedersen, Anders Bro; Andersen, Peter Bach; Sørensen, Thomas Meier; Martinenas, Sergejus


    The present invention provides an electric vehicle charging controller. The charging controller comprises a first interface connectable to an electric vehicle charge source for receiving a charging current, a second interface connectable to an electric vehicle for providing the charging current to a battery management system in the electric vehicle to charge a battery therein, a first communication unit for receiving a charging message via a communication network, and a control unit for contr...

  14. Meniscus Membranes For Separation (United States)

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.


    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  15. Safety shutdown separators (United States)

    Carlson, Steven Allen; Anakor, Ifenna Kingsley; Farrell, Greg Robert


    The present invention pertains to electrochemical cells which comprise (a) an anode; (b) a cathode; (c) a solid porous separator, such as a polyolefin, xerogel, or inorganic oxide separator; and (d) a nonaqueous electrolyte, wherein the separator comprises a porous membrane having a microporous coating comprising polymer particles which have not coalesced to form a continuous film. This microporous coating on the separator acts as a safety shutdown layer that rapidly increases the internal resistivity and shuts the cell down upon heating to an elevated temperature, such as C. Also provided are methods for increasing the safety of an electrochemical cell by utilizing such separators with a safety shutdown layer.

  16. Electric vehicle battery charging controller

    DEFF Research Database (Denmark)


    The present invention provides an electric vehicle charging controller. The charging controller comprises a first interface connectable to an electric vehicle charge source for receiving a charging current, a second interface connectable to an electric vehicle for providing the charging current...... to a battery management system in the electric vehicle to charge a battery therein, a first communication unit for receiving a charging message via a communication network, and a control unit for controlling a charging current provided from the charge source to the electric vehicle, the controlling at least...

  17. Acoustofluidic bacteria separation (United States)

    Li, Sixing; Ma, Fen; Bachman, Hunter; Cameron, Craig E.; Zeng, Xiangqun; Huang, Tony Jun


    Bacterial separation from human blood samples can help with the identification of pathogenic bacteria for sepsis diagnosis. In this work, we report an acoustofluidic device for label-free bacterial separation from human blood samples. In particular, we exploit the acoustic radiation force generated from a tilted-angle standing surface acoustic wave (taSSAW) field to separate Escherichia coli from human blood cells based on their size difference. Flow cytometry analysis of the E. coli separated from red blood cells shows a purity of more than 96%. Moreover, the label-free electrochemical detection of the separated E. coli displays reduced non-specific signals due to the removal of blood cells. Our acoustofluidic bacterial separation platform has advantages such as label-free separation, high biocompatibility, flexibility, low cost, miniaturization, automation, and ease of in-line integration. The platform can be incorporated with an on-chip sensor to realize a point-of-care sepsis diagnostic device.

  18. Rapid chemical separations

    CERN Document Server

    Trautmann, N


    A survey is given on the progress of fast chemical separation procedures during the last few years. Fast, discontinuous separation techniques are illustrated by a procedure for niobium. The use of such techniques for the chemical characterization of the heaviest known elements is described. Other rapid separation methods from aqueous solutions are summarized. The application of the high speed liquid chromatography to the separation of chemically similar elements is outlined. The use of the gas jet recoil transport method for nuclear reaction products and its combination with a continuous solvent extraction technique and with a thermochromatographic separation is presented. Different separation methods in the gas phase are briefly discussed and the attachment of a thermochromatographic technique to an on-line mass separator is shown. (45 refs).

  19. Functional heterogeneity of photosystem II in domain specific regions of the thylakoid membrane of spinach (Spinacia oleracea L.). (United States)

    Veerman, John; McConnell, Michael D; Vasil'ev, Sergei; Mamedov, Fikret; Styring, Stenbjörn; Bruce, Doug


    A mild sonication and phase fractionation method has been used to isolate five regions of the thylakoid membrane in order to characterize the functional lateral heterogeneity of photosynthetic reaction centers and light harvesting complexes. Low-temperature fluorescence and absorbance spectra, absorbance cross-section measurements, and picosecond time-resolved fluorescence decay kinetics were used to determine the relative amounts of photosystem II (PSII) and photosystem I (PSI), to determine the relative PSII antenna size, and to characterize the excited-state dynamics of PSI and PSII in each fraction. Marked progressive increases in the proportion of PSI complexes were observed in the following sequence: grana core (BS), whole grana (B3), margins (MA), stroma lamellae (T3), and purified stromal fraction (Y100). PSII antenna size was drastically reduced in the margins of the grana stack and stroma lamellae fractions as compared to the grana. Picosecond time-resolved fluorescence decay kinetics of PSII were characterized by three exponential decay components in the grana fractions, and were found to have only two decay components with slower lifetimes in the stroma. Results are discussed in the framework of existing models of chloroplast thylakoid membrane lateral heterogeneity and the PSII repair cycle. Kinetic modeling of the PSII fluorescence decay kinetics revealed that PSII populations in the stroma and grana margin fractions possess much slower primary charge separation rates and decreased photosynthetic efficiency when compared to PSII populations in the grana stack.

  20. Charge gradient microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roelofs, Andreas; Hong, Seungbum


    A method for rapid imaging of a material specimen includes positioning a tip to contact the material specimen, and applying a force to a surface of the material specimen via the tip. In addition, the method includes moving the tip across the surface of the material specimen while removing electrical charge therefrom, generating a signal produced by contact between the tip and the surface, and detecting, based on the data, the removed electrical charge induced through the tip during movement of the tip across the surface. The method further includes measuring the detected electrical charge.

  1. Hydrodynamics and Elasticity of Charged Black Branes

    DEFF Research Database (Denmark)

    Gath, Jakob

    We consider long-wavelength perturbations of charged black branes to first order in a uidelastic derivative expansion. At first order the perturbations decouple and we treat the hydrodynamic and elastic perturbations separately. To put the results in a broader perspective, we present the rst......-order corrected dynamics of uid branes carrying higher-form charge by obtaining the general form of their equations of motion to pole-dipole order in the absence of external forces. To monopole order, we characterize the corresponding effective theory of viscous uid branes by writing down the general form......)isotropic uid branes in terms of two sets of response coecients, the Young modulus and the piezoelectric moduli. We subsequently consider a large class of examples in gravity of this effective theory. In particular, we consider dilatonic black p-branes in two different settings: charged under a Maxwell gauge...

  2. Charged cosmological black hole (United States)

    Moradi, Rahim; Stahl, Clément; Firouzjaee, Javad T.; Xue, She-Sheng


    The cosmological black holes are black holes living not in an asymptotically flat universe but in an expanding spacetime. They have a rich dynamics especially for their mass and horizon. In this article, we perform a natural step in investigating this new type of black hole: we consider the possibility of a charged cosmological black hole. We derive the general equations of motion governing its dynamics and report a new analytic solution for the special case of the charged Lematre-Tolman-Bondi equations of motion that describe a charged cosmological black hole. We then study various relevant quantities for the characterization of the black hole, such as the C-function, the effect of the charge on the black hole flux, and the nature of the singularity. We also perform numerical investigations to strengthen our results. Finally, we challenge a model of gamma ray burst within our framework.

  3. EV Charging Infrastructure Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Karner, Donald [Electric Transportation Inc., Rogers, AR (United States); Garetson, Thomas [Electric Transportation Inc., Rogers, AR (United States); Francfort, Jim [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    As highlighted in the U.S. Department of Energy’s EV Everywhere Grand Challenge, vehicle technology is advancing toward an objective to “… produce plug-in electric vehicles that are as affordable and convenient for the average American family as today’s gasoline-powered vehicles …” [1] by developing more efficient drivetrains, greater battery energy storage per dollar, and lighter-weight vehicle components and construction. With this technology advancement and improved vehicle performance, the objective for charging infrastructure is to promote vehicle adoption and maximize the number of electric miles driven. The EV Everywhere Charging Infrastructure Roadmap (hereafter referred to as Roadmap) looks forward and assumes that the technical challenges and vehicle performance improvements set forth in the EV Everywhere Grand Challenge will be met. The Roadmap identifies and prioritizes deployment of charging infrastructure in support of this charging infrastructure objective for the EV Everywhere Grand Challenge

  4. Water Quality Protection Charges (United States)

    Montgomery County of Maryland — The Water Quality Protection Charge (WQPC) is a line item on your property tax bill. WQPC funds many of the County's clean water initiatives including: • Restoration...

  5. Space-Charge Effect

    CERN Document Server

    Chauvin, N.


    First, this chapter introduces the expressions for the electric and magnetic space-charge internal fields and forces induced by high-intensity beams. Then, the root-mean-square equation with space charge is derived and discussed. In the third section, the one-dimensional Child-Langmuir law, which gives the maximum current density that can be extracted from an ion source, is exposed. Space-charge compensation can occur in the low-energy beam transport lines (located after the ion source). This phenomenon, which counteracts the spacecharge defocusing effect, is explained and its main parameters are presented. The fifth section presents an overview of the principal methods to perform beam dynamics numerical simulations. An example of a particles-in-cells code, SolMaxP, which takes into account space-charge compensation, is given. Finally, beam dynamics simulation results obtained with this code in the case of the IFMIF injector are presented.

  6. Electric Vehicle Charging Modeling


    Grahn, Pia


    With an electrified passenger transportation fleet, carbon dioxide emissions could be reduced significantly depending on the electric power production mix. Increased electric power consumption due to electric vehicle charging demands of electric vehicle fleets may be met by increased amount of renewable power production in the electrical systems. With electric vehicle fleets in the transportation system there is a need for establishing an electric vehicle charging infrastructure that distribu...

  7. MOSFET Electric-Charge Sensor (United States)

    Robinson, Paul A., Jr.


    Charged-particle probe compact and consumes little power. Proposed modification enables metal oxide/semiconductor field-effect transistor (MOSFET) to act as detector of static electric charges or energetic charged particles. Thickened gate insulation acts as control structure. During measurements metal gate allowed to "float" to potential of charge accumulated in insulation. Stack of modified MOSFET'S constitutes detector of energetic charged particles. Each gate "floats" to potential induced by charged-particle beam penetrating its layer.

  8. Polyelectrolytes with sterically hindered anionic charges

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, T.F.; Liu, H.; Okamoto, Y.; Lee, H.S.; Skotheim, T.A. (Polytechnic Inst. of Brooklyn, NY (USA); Brookhaven National Lab., Upton, NY (USA))


    The central problem in the development of single phase polymer electrolytes with exclusive cation conduction has been inadequate ion mobility due to extensive ion pairing between the mobile cation and the covalently attached anion. We have developed a new class of single ion conducting polymers, or polyelectrolytes, based on highly flexible polysiloxane backbones and attached sterically hindered phenolate anions. The combination of a highly delocalized and sterically enclosed anionic charged separation and consequently enhanced cation mobility. 10 refs., 2 figs.

  9. The ADvanced SEParation (ADSEP) (United States)


    The ADvanced SEParation (ADSEP) commercial payload is making use of major advances in separation technology: The Phase Partitioning Experiment (PPE); the Micorencapsulation experiment; and the Hemoglobin Separation Experiment (HSE). Using ADSEP, commercial researchers will attempt to determine the partition coefficients for model particles in a two-phase system. With this information, researchers can develop a higher resolution, more effective cell isolation procedure that can be used for many different types of research and for improved health care. The advanced separation technology is already being made available for use in ground-based laboratories.

  10. Separation of flow

    CERN Document Server

    Chang, Paul K


    Interdisciplinary and Advanced Topics in Science and Engineering, Volume 3: Separation of Flow presents the problem of the separation of fluid flow. This book provides information covering the fields of basic physical processes, analyses, and experiments concerning flow separation.Organized into 12 chapters, this volume begins with an overview of the flow separation on the body surface as discusses in various classical examples. This text then examines the analytical and experimental results of the laminar boundary layer of steady, two-dimensional flows in the subsonic speed range. Other chapt

  11. Nonterminal Separating Macro Grammars

    NARCIS (Netherlands)

    Hogendorp, Jan Anne


    We extend the concept of nonterminal separating (or NTS) context-free grammar to nonterminal separating $m$-macro grammar where the mode of derivation $m$ is equal to "unrestricted". "outside-in' or "inside-out". Then we show some (partial) characterization results for these NTS $m$-macro grammars.

  12. Working with Separation (United States)

    Krugman, Dorothy C.


    Discusses the role of the caseworker in providing support to children experiencing separation from their families and emphasizes the need to recognize that there are differences between those separation experiences dictated by the needs of children and those dictated by arbitrary or noncasework factors. (AJ)

  13. Separation anxiety disorder

    NARCIS (Netherlands)

    Nauta, M.H.; Emmelkamp, P.M.G.; Sturmey, P.; Hersen, M.


    Separation anxiety disorder (SAD) is the only anxiety disorder that is specific to childhood; however, SAD has hardly ever been addressed as a separate disorder in clinical trials investigating treatment outcome. So far, only parent training has been developed specifically for SAD. This particular

  14. Social Separation in Monkeys. (United States)

    Mineka, Susan; Suomi, Stephen J.


    Reviews phenomena associated with social separation from attachment objects in nonhuman primates. Evaluates four theoretical treatments of separation in light of existing data: Bowlby's attachment-object-loss theory, Kaufman's conservation-withdrawal theory, Seligman's learned helplessness theory, and Solomon and Corbit's opponent-process theory.…

  15. Charge densities and charge noise in mesoscopic conductors

    Indian Academy of Sciences (India)

    February 2002 physics pp. 241–257. Charge densities and charge noise in mesoscopic conductors ... the charge noise [6] based on the scattering approach. Similar to the discussion of linear ...... a novel resistance which determines the dissipative effects in charging and decharging a. 254. Pramana – J. Phys., Vol. 58, No.

  16. Taming Highly Charged Radioisotopes (United States)

    Chowdhury, Usman; Eberhardt, Benjamin; Jang, Fuluni; Schultz, Brad; Simon, Vanessa; Delheij, Paul; Dilling, Jens; Gwinner, Gerald


    The precise and accurate mass of short-lived radioisotopes is a very important parameter in physics. Contribution to the improvement of nuclear models, metrological standard fixing and tests of the unitarity of the Caibbibo-Kobayashi-Maskawa (CKM) matrix are a few examples where the mass value plays a major role. TRIUMF's ion trap for atomic and nuclear physics (TITAN) is a unique facility of three online ion traps that enables the mass measurement of short-lived isotopes with high precision (˜10-8). At present TITAN's electron beam ion trap (EBIT) increases the charge state to increase the precision, but there is no facility to significantly reduce the energy spread introduced by the charge breeding process. The precision of the measured mass of radioisotopes is linearly dependent on the charge state while the energy spread of the charged radioisotopes affects the precision adversely. To boost the precision level of mass measurement at TITAN without loosing too many ions, a cooler Penning trap (CPET) is being developed. CPET is designed to use either positively (proton) or negatively (electron) charged particles to reduce the energy spread via sympathetic cooling. Off-line setup of CPET is complete. Details of the working principles and updates are presented

  17. Simulations of counterions at charged plates. (United States)

    Moreira, A G; Netz, R R


    separation. Depending on the thermodynamic ensemble, the phase diagram exhibits a discontinuous transition where the inter-wall distance jumps to infinity (in the absence of a chemical potential coupling to the inter-wall distance, as for charged lamellae in excess solvent) or a critical point where two coexisting states with different inter-wall distance become indistinguishable (in the presence of a chemical potential, as for charged lamellae with a finite fixed solvent fraction). The attractive pressure decays with the inter-wall distance as an inverse cube, similar to analytic predictions, although the amplitude differs by an order of magnitude from previous theoretical results. Finally, we discuss in detail our simulation methods and compare the finite-size scaling behavior of different boundary conditions (periodic, minimal image and open).

  18. Effective Electrostatic Interactions Between Two Overall Neutral Surfaces with Quenched Charge Heterogeneity Over Atomic Length Scale (United States)

    Zhou, S.


    Using Monte Carlo results as a reference, a classical density functional theory ( CDFT) is shown to reliably predict the forces between two heterogeneously charged surfaces immersed in an electrolyte solution, whereas the Poisson-Boltzmann ( PB) theory is demonstrated to deteriorate obviously for the same system even if the system parameters considered fall within the validity range of the PB theory in the homogeneously charged surfaces. By applying the tested CDFT, we study the effective electrostatic potential of mean force ( EPMF) between two face-face planar and hard surfaces of zero net charge on which positive and negative charges are separated and considered to present as discontinuous spots on the inside edges of the two surfaces. Main conclusions are summarized as follows: (i) strength of the EPMF in the surface charge separation case is very sensitively and positively correlated with the surface charge separation level and valency of the salt ion. Particularly, the charge separation level and the salt ion valency have a synergistic effect, which makes high limit of the EPMF strength in the surface charge separation case significantly go beyond that of the ideal homogeneously charged surface counterpart at average surface charge density similar to the average surface positive or negative charge density in the charge separation case. (ii) The surface charge distribution patterns mainly influence sign of the EPMF: symmetrical and asymmetrical patterns induce repulsive and attractive (at small distances) EPMF, respectively; but with low valency salt ions and low charge separation level the opposite may be the case. With simultaneous presence of both higher valency cation and anion, the EPMF can be repulsive at intermediate distances for asymmetrical patterns. (iii) Salt ion size has a significant impact, which makes the EPMF tend to become more and more repulsive with the ion diameter regardless of the surface charge distribution patterns and the valency of

  19. Structured near-infrared Magnetic Circular Dichroism spectra of the Mn4CaO5 cluster of PSII in T. vulcanus are dominated by Mn(IV) d-d 'spin-flip' transitions. (United States)

    Morton, Jennifer; Chrysina, Maria; Craig, Vincent S J; Akita, Fusamichi; Nakajima, Yoshiki; Lubitz, Wolfgang; Cox, Nicholas; Shen, Jian-Ren; Krausz, Elmars


    Photosystem II passes through four metastable S-states in catalysing light-driven water oxidation. Variable temperature variable field (VTVH) Magnetic Circular Dichroism (MCD) spectra in PSII of Thermosynochococcus (T.) vulcanus for each S-state are reported. These spectra, along with assignments, provide a new window into the electronic and magnetic structure of Mn4CaO5. VTVH MCD spectra taken in the S2 state provide a clear g=2, S=1/2 paramagnetic characteristic, which is entirely consistent with that known by EPR. The three features, seen as positive (+) at 749nm, negative (-) at 773nm and (+) at 808nm are assigned as 4A→2E spin-flips within the d3 configuration of the Mn(IV) centres present. This assignment is supported by comparison(s) to spin-flips seen in a range of Mn(IV) materials. S3 exhibits a more intense (-) MCD peak at 764nm and has a stronger MCD saturation characteristic. This S3 MCD saturation behaviour can be accurately modelled using parameters taken directly from analyses of EPR spectra. We see no evidence for Mn(III) d-d absorption in the near-IR of any S-state. We suggest that Mn(IV)-based absorption may be responsible for the well-known near-IR induced changes induced in S2 EPR spectra of T. vulcanus and not Mn(III)-based, as has been commonly assumed. Through an analysis of the nephelauxetic effect, the excitation energy of S-state dependent spin-flips seen may help identify coordination characteristics and changes at each Mn(IV). A prospectus as to what more detailed S-state dependent MCD studies promise to achieve is outlined. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Chromatographic hydrogen isotope separation (United States)

    Aldridge, Frederick T.


    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  1. Rotary drum separator system (United States)

    Barone, Michael R. (Inventor); Murdoch, Karen (Inventor); Scull, Timothy D. (Inventor); Fort, James H. (Inventor)


    A rotary phase separator system generally includes a step-shaped rotary drum separator (RDS) and a motor assembly. The aspect ratio of the stepped drum minimizes power for both the accumulating and pumping functions. The accumulator section of the RDS has a relatively small diameter to minimize power losses within an axial length to define significant volume for accumulation. The pumping section of the RDS has a larger diameter to increase pumping head but has a shorter axial length to minimize power losses. The motor assembly drives the RDS at a low speed for separating and accumulating and a higher speed for pumping.

  2. Double Charged Surface Layers in Lead Halide Perovskite Crystals

    KAUST Repository

    Sarmah, Smritakshi P.


    Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.

  3. Radiochemical separation of Cobalt

    NARCIS (Netherlands)

    Erkelens, P.C. van


    A method is described for the radiochemical separation of cobalt based on the extraordinary stability of cobalt diethyldithiocarbamate. Interferences are few; only very small amounts of zinc and iron accompany cobalt, which is important in neutron-activation analysis.

  4. Separation Anxiety (For Parents) (United States)

    ... older child, there might be another problem, like bullying or abuse. Separation anxiety is different from the normal feelings older kids have when they don't want a parent to leave (which can usually be overcome if ...

  5. Separation by solvent extraction (United States)

    Holt, Jr., Charles H.


    17. A process for separating fission product values from uranium and plutonium values contained in an aqueous solution, comprising adding an oxidizing agent to said solution to secure uranium and plutonium in their hexavalent state; contacting said aqueous solution with a substantially water-immiscible organic solvent while agitating and maintaining the temperature at from to C. until the major part of the water present is frozen; continuously separating a solid ice phase as it is formed; separating a remaining aqueous liquid phase containing fission product values and a solvent phase containing plutonium and uranium values from each other; melting at least the last obtained part of said ice phase and adding it to said separated liquid phase; and treating the resulting liquid with a new supply of solvent whereby it is practically depleted of uranium and plutonium.

  6. Separable Arrowhead Microneedles (United States)

    Chu, Leonard Y.; Prausnitz, Mark R.


    Hypodermic needles cause pain and bleeding, produce biohazardous sharp waste and require trained personnel. To address these issues, we introduce separable arrowhead microneedles that rapidly and painlessly deliver drugs and vaccines to the skin. These needles are featured by micron-size sharp tips mounted on blunt shafts. Upon insertion in the skin, the sharp-tipped polymer arrowheads encapsulating drug separate from their metal shafts and remain embedded in the skin for subsequent dissolution and drug release. The blunt metal shafts can then be discarded. Due to rapid separation of the arrowhead tips from the shafts within seconds, administration using arrowhead microneedles can be carried out rapidly, while drug release kinetics can be independently controlled based on separable arrowhead formulation. Thus, drug and vaccine delivery using arrowhead microneedles are designed to offer a quick, convenient, safe and potentially self-administered method of drug delivery as an alternative to hypodermic needles. PMID:21047538

  7. Natural isoforms of the Photosystem II D1 subunit differ in photoassembly efficiency of the water-oxidizing complex. (United States)

    Vinyard, David J; Sun, Jennifer S; Gimpel, Javier; Ananyev, Gennady M; Mayfield, Stephen P; Charles Dismukes, G


    Oxygenic photosynthesis efficiency at increasing solar flux is limited by light-induced damage (photoinhibition) of Photosystem II (PSII), primarily targeting the D1 reaction center subunit. Some cyanobacteria contain two natural isoforms of D1 that function better under low light (D1:1) or high light (D1:2). Herein, rates and yields of photoassembly of the Mn4CaO5 water-oxidizing complex (WOC) from the free inorganic cofactors (Mn(2+), Ca(2+), water, electron acceptor) and apo-WOC-PSII are shown to differ significantly: D1:1 apo-WOC-PSII exhibits a 2.3-fold faster rate-limiting step of photoassembly and up to seven-fold faster rate to the first light-stable Mn(3+) intermediate, IM1*, but with a much higher rate of photoinhibition than D1:2. Conversely, D1:2 apo-WOC-PSII assembles slower but has up to seven-fold higher yield, achieved by a higher quantum yield of charge separation and slower photoinhibition rate. These results confirm and extend previous observations of the two holoenzymes: D1:2-PSII has a greater quantum yield of primary charge separation, faster [P680 (+) Q A (-) ] charge recombination and less photoinhibition that results in a slower rate and higher yield of photoassembly of its apo-WOC-PSII complex. In contrast, D1:1-PSII has a lower quantum yield of primary charge separation, a slower [P680 (+) Q A (-) ] charge recombination rate, and faster photoinhibition that together result in higher rate but lower yield of photoassembly at higher light intensities. Cyanobacterial PSII reaction centers that contain the high- and low-light D1 isoforms can tailor performance to optimize photosynthesis at varying light conditions, with similar consequences on their photoassembly kinetics and yield. These different efficiencies of photoassembly versus photoinhibition impose differential costs for biosynthesis as a function of light intensity.

  8. Research on Battery Charging-Discharging in New Energy Systems


    Che Yanbo; Zhou Yan; Sun Yue; Hu Bo


    As an energy storage component, the battery plays increasingly important role in new energy industry. Charging and discharging system is the vital part of the application of the battery, but the charge and discharge are always designed separately and carried by different part in the traditional application. Additionally, most battery discharge mode and method are always simplified which cannot ensure to meet the demand of power utilization. In the actual energy storage system, the design of t...

  9. Hydrogen separation process (United States)

    Mundschau, Michael [Longmont, CO; Xie, Xiaobing [Foster City, CA; Evenson, IV, Carl; Grimmer, Paul [Longmont, CO; Wright, Harold [Longmont, CO


    A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than C., to a hydrogen separation membrane system comprising a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than C., to an integrated water gas shift/hydrogen separation membrane system wherein the hydrogen separation membrane system comprises a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for pretreating a membrane, comprising: heating the membrane to a desired operating temperature and desired feed pressure in a flow of inert gas for a sufficient time to cause the membrane to mechanically deform; decreasing the feed pressure to approximately ambient pressure; and optionally, flowing an oxidizing agent across the membrane before, during, or after deformation of the membrane. A method of supporting a hydrogen separation membrane system comprising selecting a hydrogen separation membrane system comprising one or more catalyst outer layers deposited on a hydrogen transport membrane layer and sealing the hydrogen separation membrane system to a porous support.

  10. System and method for charging a plug-in electric vehicle (United States)

    Bassham, Marjorie A.; Spigno, Jr., Ciro A.; Muller, Brett T.; Newhouse, Vernon L.


    A charging system and method that may be used to automatically apply customized charging settings to a plug-in electric vehicle, where application of the settings is based on the vehicle's location. According to an exemplary embodiment, a user may establish and save a separate charging profile with certain customized charging settings for each geographic location where they plan to charge their plug-in electric vehicle. Whenever the plug-in electric vehicle enters a new geographic area, the charging method may automatically apply the charging profile that corresponds to that area. Thus, the user does not have to manually change or manipulate the charging settings every time they charge the plug-in electric vehicle in a new location.

  11. System and method for charging a plug-in electric vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Bassham, Marjorie A.; Spigno, Jr., Ciro A.; Muller, Brett T.; Newhouse, Vernon L.


    A charging system and method that may be used to automatically apply customized charging settings to a plug-in electric vehicle, where application of the settings is based on the vehicle's location. According to an exemplary embodiment, a user may establish and save a separate charging profile with certain customized charging settings for each geographic location where they plan to charge their plug-in electric vehicle. Whenever the plug-in electric vehicle enters a new geographic area, the charging method may automatically apply the charging profile that corresponds to that area. Thus, the user does not have to manually change or manipulate the charging settings every time they charge the plug-in electric vehicle in a new location.

  12. Analysis of S2QA- charge recombination with the Arrhenius, Eyring and Marcus theories. (United States)

    Rantamäki, Susanne; Tyystjärvi, Esa


    The Q band of photosynthetic thermoluminescence, measured in the presence of a herbicide that blocks electron transfer from PSII, is associated with recombination of the S(2)Q(A)(-) charge pair. The same charge recombination reaction can be monitored with chlorophyll fluorescence. It has been shown that the recombination occurs via three competing routes of which one produces luminescence. In the present study, we measured the thermoluminescence Q band and the decay of chlorophyll fluorescence yield after a single turnover flash at different temperatures from spinach thylakoids. The data were analyzed using the commonly used Arrhenius theory, the Eyring rate theory and the Marcus theory of electron transfer. The fitting error was minimized for both thermoluminescence and fluorescence by adjusting the global, phenomenological constants obtained when the reaction rate theories were applied to the multi-step recombination reaction. For chlorophyll fluorescence, all three theories give decent fits. The peak position of the thermoluminescence Q band is correct by all theories but the form of the Q band is somewhat different in curves predicted by the three theories. The Eyring and Marcus theories give good fits for the decreasing part of the thermoluminescence curve and Marcus theory gives the closest fit for the rising part. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Spacecraft Surface Charging Handbook (United States)


    Location High potential si&e of C Pulser output Wires on drive pU~ Sensor Woih-voltuge Probe Cuwaln prole Current protw Connection tard ...477, 1982. 316 Gabriel , S. B. and Garrett, H. B.. "An Overview of Charging Environments," Space Environmental Effects on Materials Workshop, p. 495

  14. Charged fluids with symmetries

    Indian Academy of Sciences (India)

    Abstract. We investigate the role of symmetries for charged perfect fluids by assuming that spacetime admits a conformal Killing vector. The existence of a conformal symmetry places restrictions on the model. It is possible to find a general relationship for the Lie derivative of the electromagnetic field along the integral curves ...

  15. Charged particle beams

    CERN Document Server

    Humphries, Stanley


    Detailed enough for a text and sufficiently comprehensive for a reference, this volume addresses topics vital to understanding high-power accelerators and high-brightness-charged particle beams. Subjects include stochastic cooling, high-brightness injectors, and the free electron laser. Humphries provides students with the critical skills necessary for the problem-solving insights unique to collective physics problems. 1990 edition.

  16. An Investigation into Separation of Impurity from Saffron Stigma Using an Electrostatic Separator

    Directory of Open Access Journals (Sweden)

    H Mortezapour


    Full Text Available In the present study, a laboratory electrostatic separator was constructed and its separation potential of white saffron impurities from stigma was investigated. The device was comprised of a nylon ribbon which moves in contact with a woolen brush and was charged by the triboelectric effect. The charged ribbon, then, moved over the material pan. Since the electrostatic behavior vary from various materials, their attraction to the ribbon differ. The separation tests were conducted at three levels of ribbon position (with 1.5, 2.5 and 3.5 cm from the material pan, three drum speeds (50, 60 and 70 rpm and three working times (120, 18 and 240 seconds. The results showed that material absorption increased as working time increased and the ribbon distance decreased. Meanwhile, rising the speed from 50 to 60 rpm improved material absorption while, more increasing from 60 to 70 rpm reduced the absorption. A maximum impurity separation of 97% was observed with ribbon distance of 1.5 cm, ribbon speed of 60 rpm and working for 240 seconds. The minimum stigma losses were found to be about 2% when the ribbon distance and speed were 3.5 cm and 70 rpm, respectively, and the separator worked for 120 seconds.

  17. Raising the barrier for photoinduced DNA charge injection with a cyclohexyl artificial base pair. (United States)

    Singh, Arunoday P N; Harris, Michelle A; Young, Ryan M; Miller, Stephen A; Wasielewski, Michael R; Lewis, Frederick D


    The effects of an artificial cyclohexyl base pair on the quantum yields of fluorescence and dynamics of charge separation and charge recombination have been investigated for several synthetic DNA hairpins. The hairpins possess stilbenedicarboxamide, perylenediimide, or naphthalenediimide linkers and base-paired stems. In the absence of the artificial base pair hole injection into both adenine and guanine purine bases is exergonic and irreversible, except in the case of stilbene with adenine for which it is slightly endergonic and reversible. Insertion of the artificial base pair renders hole injection endergonic or isoergonic except in the case of the powerful naphthalene acceptor for which it remains exergonic. Both hole injection and charge recombination are slower for the naphthalene acceptor in the presence of the artificial base pair than in its absence. The effect of an artificial base pair on charge separation and charge recombination in hairpins possessing stilbene and naphthalene acceptor linkers and a stilbenediether donor capping group has also been investigated. In the case of the stilbene acceptor-stilbene donor capped hairpins photoinduced charge separation across six base pairs is efficient in the absence of the artificial base pair but does not occur in its presence. In the case of the naphthalene acceptor-stilbene donor capped hairpins the artificial base pair slows but does not stop charge separation and charge recombination, leading to the formation of long-lived charge separated states.

  18. Determination of sin$^{2}\\vartheta^{eff}_{W}$ using jet charge measurements in hadronic Z decays

    CERN Document Server

    Buskulic, Damir; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Chmeissani, M; Crespo, J M; Delfino, M C; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Alemany, R; Bazarko, A O; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Mir, L M; Moneta, L; Oest, T; Palla, Fabrizio; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wagner, A; Wildish, T; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Wäänänen, A; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Abbaneo, D; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Konstantinidis, N P; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Köksal, A; Letho, M; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Büscher, V; Cowan, G D; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Aleppo, M; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G


    The electroweak mixing angle is determined with high precision from measurements of the mean difference between forward and backward hemisphere charges in hadronic decays of the Z. A data sample of 2.5 million hadronic Z decays recorded over the period 1990 to 1994 in the ALEPH detector at LEP is used. The mean charge separation between event hemispheres containing the original quark and antiquark is measured for b-bbar and c-cbar events in subsamples selected by their long lifetimes or using fast D*'s. The corresponding average charge separation for light quarks is measured in an inclusive sample from the anticorrelation between charges of opposite hemispheres and agrees with predictions of hadronisation models with a precision of 2%. It is shown that differences between light quark charge separations and the measured average can be determined using hadronisation models, with systematic uncertainties constrained by measurements of inclusive production of kaons, protons and lambda's. The separations are used ...

  19. Effective Charge Carrier Utilization in Photocatalytic Conversions. (United States)

    Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong


    morphology of nanostructured photocatalysts can reduce the migration distance of charge carriers. Improving the conductivity of photocatalysts by using graphitic materials can also improve the transport of charge carriers. Upon charge carrier migration, electrons and holes also tend to recombine. The suppression of recombination can be achieved by constructing heterojunctions that enhance charge separation in the photocatalysts. Surface states acting as recombination centers should also be removed to improve the photocatalytic efficiency. Moreover, surface reactions, which are the core chemical processes during the solar energy conversion, can be enhanced by applying cocatalysts as well as suppressing side reactions. All of these strategies have been proved to be essential for enhancing the activities of semiconductor photocatalysts. It is hoped that delicate manipulation of photogenerated charge carriers in semiconductor photocatalysts will hold the key to effective solar-to-chemical energy conversion.

  20. Imaging charge transfer in iodomethane upon x-ray photoabsorption. (United States)

    Erk, Benjamin; Boll, Rebecca; Trippel, Sebastian; Anielski, Denis; Foucar, Lutz; Rudek, Benedikt; Epp, Sascha W; Coffee, Ryan; Carron, Sebastian; Schorb, Sebastian; Ferguson, Ken R; Swiggers, Michele; Bozek, John D; Simon, Marc; Marchenko, Tatiana; Küpper, Jochen; Schlichting, Ilme; Ullrich, Joachim; Bostedt, Christoph; Rolles, Daniel; Rudenko, Artem


    Studies of charge transfer are often hampered by difficulties in determining the charge localization at a given time. Here, we used ultrashort x-ray free-electron laser pulses to image charge rearrangement dynamics within gas-phase iodomethane molecules during dissociation induced by a synchronized near-infrared (NIR) laser pulse. Inner-shell photoionization creates positive charge, which is initially localized on the iodine atom. We map the electron transfer between the methyl and iodine fragments as a function of their interatomic separation set by the NIR-x-ray delay. We observe signatures of electron transfer for distances up to 20 angstroms and show that a realistic estimate of its effective spatial range can be obtained from a classical over-the-barrier model. The presented technique is applicable for spatiotemporal imaging of charge transfer dynamics in a wide range of molecular systems. Copyright © 2014, American Association for the Advancement of Science.

  1. Gulf stream separation dynamics (United States)

    Schoonover, Joseph

    Climate models currently struggle with the more traditional, coarse ( O(100 km) ) representation of the ocean. In these coarse ocean simulations, western boundary currents are notoriously difficult to model accurately. The modeled Gulf Stream is typically seen exhibiting a mean pathway that is north of observations, and is linked to a warm sea-surface temperature bias in the Mid-Atlantic Bight. Although increased resolution ( O(10 km) ) improves the modeled Gulf Stream position, there is no clean recipe for obtaining the proper pathway. The 70 year history of literature on the Gulf Stream separation suggests that we have not reached a resolution on the dynamics that control the current's pathway just south of the Mid-Atlantic Bight. Without a concrete knowledge on the separation dynamics, we cannot provide a clean recipe for accurately modeling the Gulf Stream at increased resolutions. Further, any reliable parameterization that yields a realistic Gulf Stream path must express the proper physics of separation. The goal of this dissertation is to determine what controls the Gulf Stream separation. To do so, we examine the results of a model intercomparison study and a set of numerical regional terraforming experiments. It is argued that the separation is governed by local dynamics that are most sensitive to the steepening of the continental shelf, consistent with the topographic wave arrest hypothesis of Stern (1998). A linear extension of Stern's theory is provided, which illustrates that wave arrest is possible for a continuously stratified fluid.

  2. Charge Splitting In Situ Recorder (CSIR) for Real-Time Examination of Plasma Charging Effect in FinFET BEOL Processes (United States)

    Tsai, Yi-Pei; Hsieh, Ting-Huan; Lin, Chrong Jung; King, Ya-Chin


    A novel device for monitoring plasma-induced damage in the back-end-of-line (BEOL) process with charge splitting capability is first-time proposed and demonstrated. This novel charge splitting in situ recorder (CSIR) can independently trace the amount and polarity of plasma charging effects during the manufacturing process of advanced fin field-effect transistor (FinFET) circuits. Not only does it reveal the real-time and in situ plasma charging levels on the antennas, but it also separates positive and negative charging effect and provides two independent readings. As CMOS technologies push for finer metal lines in the future, the new charge separation scheme provides a powerful tool for BEOL process optimization and further device reliability improvements.

  3. Simultaneous Nanoscale Surface Charge and Topographical Mapping. (United States)

    Perry, David; Al Botros, Rehab; Momotenko, Dmitry; Kinnear, Sophie L; Unwin, Patrick R


    Nanopipettes are playing an increasingly prominent role in nanoscience, for sizing, sequencing, delivery, detection, and mapping interfacial properties. Herein, the question of how to best resolve topography and surface charge effects when using a nanopipette as a probe for mapping in scanning ion conductance microscopy (SICM) is addressed. It is shown that, when a bias modulated (BM) SICM scheme is used, it is possible to map the topography faithfully, while also allowing surface charge to be estimated. This is achieved by applying zero net bias between the electrode in the SICM tip and the one in bulk solution for topographical mapping, with just a small harmonic perturbation of the potential to create an AC current for tip positioning. Then, a net bias is applied, whereupon the ion conductance current becomes sensitive to surface charge. Practically this is optimally implemented in a hopping-cyclic voltammetry mode where the probe is approached at zero net bias at a series of pixels across the surface to reach a defined separation, and then a triangular potential waveform is applied and the current response is recorded. Underpinned with theoretical analysis, including finite element modeling of the DC and AC components of the ionic current flowing through the nanopipette tip, the powerful capabilities of this approach are demonstrated with the probing of interfacial acid-base equilibria and high resolution imaging of surface charge heterogeneities, simultaneously with topography, on modified substrates.

  4. Mass Separation by Metamaterials (United States)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin


    Being able to manipulate mass flow is critically important in a variety of physical processes in chemical and biomolecular science. For example, separation and catalytic systems, which requires precise control of mass diffusion, are crucial in the manufacturing of chemicals, crystal growth of semiconductors, waste recovery of biological solutes or chemicals, and production of artificial kidneys. Coordinate transformations and metamaterials are powerful methods to achieve precise manipulation of molecular diffusion. Here, we introduce a novel approach to obtain mass separation based on metamaterials that can sort chemical and biomolecular species by cloaking one compound while concentrating the other. A design strategy to realize such metamaterial using homogeneous isotropic materials is proposed. We present a practical case where a mixture of oxygen and nitrogen is manipulated using a metamaterial that cloaks nitrogen and concentrates oxygen. This work lays the foundation for molecular mass separation in biophysical and chemical systems through metamaterial devices.

  5. Glycosaminoglycan blotting and detection after electrophoresis separation. (United States)

    Volpi, Nicola; Maccari, Francesca


    Separation of glycosaminoglycans (GAGs) by electrophoresis and their characterization to the microgram level are integral parts of biochemical research. Their blotting on membranes after electrophoresis offers the advantage to perform further analysis on single separated species such as identification with antibodies and/or recovery of single band. A method for the blotting and immobilizing of several nonsulfated and sulfated complex GAGs on membranes made hydrophilic and positively charged by cationic detergent after their separation by conventional agarose-gel electrophoresis is illustrated. This approach to the study of these complex macromolecules utilizes the capacity of agarose-gel electrophoresis to separate single species of polysaccharides from mixtures and the membrane technology for further preparative and analytical uses. Nitrocellulose membranes are derivatized with the cationic detergent cetylpyridinium chloride (CPC) and mixtures of GAGs are capillary blotted after their separation in agarose-gel electrophoresis. Single purified species of variously sulfated polysaccharides are transferred on derivatized membranes with an efficiency of 100 % and stained with alcian blue (irreversible staining) and toluidine blue (reversible staining). This enables a lower amount limit of detection of 0.1 μg. Nonsulfated polyanions, for example hyaluronic acid (HA), may also be transferred to membranes with a limit of detection of approximately 0.1-0.5 μg after irreversible or reversible staining. The membranes may be stained with reversible staining and the same lanes used for immunological detection or other applications.

  6. Measurement of Neutrino Induced, Charged Current, Charged Pion Production

    Energy Technology Data Exchange (ETDEWEB)

    Wilking, Michael Joseph [Univ. of Colorado, Boulder, CO (United States)


    Neutrinos are among the least understood particles in the standard model of particle physics. At neutrino energies in the 1 GeV range, neutrino properties are typically determined by observing the outgoing charged lepton produced in a charged current quasi-elastic interactions. The largest charged current background to these measurements comes from charged current pion production interactions, for which there is very little available data.

  7. Unity Through Separation

    DEFF Research Database (Denmark)

    Dabelsteen, Hans B.

    This PhD thesis asks how we can conceptualize the current separation doctrine of religion and politics in a country like Denmark, where the structure of the established church and peoplehood overlap. In order to answer this question, Hans Bruun Dabelsteen maps the current discussion of secularism...... into the principle of treating everybody equally (with religious freedom, equality and Danish peoplehood as the most important principles adjacent to secularism). In a study of the historical roots of the separation doctrine and two current policy cases (same-sex marriage and reforms of church governance...

  8. Gas separation membranes (United States)

    Schell, William J.


    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  9. Separation membrane development

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.W. [Savannah River Technology Center, Aiken, SC (United States)


    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  10. Spiral Flow Separator (United States)

    Robertson, Glen A.


    Proposed liquid-separating device relies on centrifugal force in liquid/liquid or liquid/solid mixture in spiral path. Operates in continuous flow at relatively high rates. Spiral tubes joined in sequence, with outlet tubes connected to joints. Cross-sectional areas of successive spiral tubes decreases by cross-sectional areas of outlet tubes. Centrifugal force pushes denser particles or liquids to outer edge of spiral, where removed from flow. Principle exploited to separate solids from wastewater, oil from fresh or salt water, or contaminants from salt water before evaporation. Also used to extract such valuable materials as precious metals from slurries.

  11. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.


    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  12. Electrostatic Separation Of Layers In Thermal Insulation (United States)

    Bhandari, Pradeep


    Layers in multilayer insulation charged to keep them separated by electrostatic repulsion, eliminating need for spacer nets. Removal of spacer nets reduces conduction of heat between layers. Insulation in question type used to slow leakage of heat into Dewar flasks containing liquid helium. Proposal originally applied to insulation in cryogenic cooling subsystems of infrared-detector systems in outer space, also appears applicable to small panels of insulation for terrestrial cryogenic equipment, provided layers contained in evacuated spaces and weight of each layer small fraction of electrostatic force upon it.

  13. Partially massless monopoles and charges (United States)

    Hinterbichler, Kurt; Rosen, Rachel A.


    Massive higher spin fields on de Sitter space exhibit enhanced gauge symmetries at special values of the mass. These fields are known as "partially massless." We study the structure of the charges and Gauss laws which characterize sources for the partially massless spin-2. Despite having a simple scalar gauge symmetry, there is a rich structure of gauge charges. The charges come in electric and magnetic varieties, each taking values in the fundamental representation of the de Sitter group. We find two invariant electriclike charges and two invariant magneticlike charges and we find the pointlike monopole solutions which carry these charges, analogous to the electric point-charge solution and Dirac monopole solution of Maxwell electrodynamics. These solutions are related by partially massless duality, analogous to the electromagnetic duality that relates electric to magnetic charges.

  14. diffusive phase separation

    Directory of Open Access Journals (Sweden)

    Nobuyuki Kenmochi


    w is constrained to have double obstacles σ*≤w≤σ* (i.e., σ* and σ* are the threshold values of w. The objective of this paper is to discuss the semigroup {S(t} associated with the phase separation model, and construct its global attractor.

  15. Fathering After Marital Separation (United States)

    Keshet, Harry Finkelstein; Rosenthal, Kristine M.


    Deals with experiences of a group of separated or divorced fathers who chose to remain fully involved in the upbringing of their children. As they underwent transition from married parenthood to single fatherhood, these men learned that meeting demands of child care contributed to personal stability and growth. (Author)

  16. Separation of Concerns

    DEFF Research Database (Denmark)

    Ernst, Erik


    Separation of concerns is a crucial concept in discussions about software engineering consequences of programming language design decisions, especially in AOSD. This paper proposes a way to formalize this concept, and argues that the given formalization is useful even if it is used primarily...


    African Journals Online (AJOL)

    B. S. Chandravanshi

    The developed coprecipitation procedure has been applied to road dust, anodic slime, industrial electronic waste materials and water samples to determine their Pd(II) levels. KEY WORDS: Palladium, Separation, Preconcentration, Carrier element free coprecipitation. INTRODUCTION. Palladium, a precious metal, is widely ...

  18. Polymide gas separation membranes (United States)

    Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz


    Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

  19. Submerged AUV Charging Station (United States)

    Jones, Jack A.; Chao, Yi; Curtin, Thomas


    Autonomous Underwater Vehicles (AUVs) are becoming increasingly important for military surveillance and mine detection. Most AUVs are battery powered and have limited lifetimes of a few days to a few weeks. This greatly limits the distance that AUVs can travel underwater. Using a series of submerged AUV charging stations, AUVs could travel a limited distance to the next charging station, recharge its batteries, and continue to the next charging station, thus traveling great distances in a relatively short time, similar to the Old West “Pony Express.” One solution is to use temperature differences at various depths in the ocean to produce electricity, which is then stored in a submerged battery. It is preferred to have the upper buoy submerged a reasonable distance below the surface, so as not to be seen from above and not to be inadvertently destroyed by storms or ocean going vessels. In a previous invention, a phase change material (PCM) is melted (expanded) at warm temperatures, for example, 15 °C, and frozen (contracted) at cooler temperatures, for example, 8 °C. Tubes containing the PCM, which could be paraffin such as pentadecane, would be inserted into a container filled with hydraulic oil. When the PCM is melted (expanded), it pushes the oil out into a container that is pressurized to about 3,000 psi (approx equals 20.7 MPa). When a valve is opened, the high-pressure oil passes through a hydraulic motor, which turns a generator and charges a battery. The low-pressure oil is finally reabsorbed into the PCM canister when the PCM tubes are frozen (contracted). Some of the electricity produced could be used to control an external bladder or a motor to the tether line, such that depth cycling is continued for a very long period of time. Alternatively, after the electricity is generated by the hydraulic motor, the exiting low-pressure oil from the hydraulic motor could be vented directly to an external bladder on the AUV, such that filling of the bladder

  20. Magnetic Forces on Moving Charges



    sim drag Simulation Drag-and-Drop Exercise Interactive Media Element This interactive tutorial provides the practice to reinforce the concept of magnetic force of moving charges. The key concepts covered include: The direction of the resultant magnetic force is always perpendicular to the plane defined by the velocity vector of the charge and the magnetic field vector., The direction of motion of the charge is also influenced by the sign/polarity of the charge., If the velocity...

  1. Charge Breeding and Production of Multiply Charged Ions in EBIS and ECRIS

    CERN Document Server

    Wenander, Frederik J C


    The REXEBIS is an Electron Beam Ion Source (EBIS) developed for charge breeding of the exotic and sometimes short-lived isotopes that are produced at ISOLDE for the REX-ISOLDE post accelerator. Bunches of singly charged radioactive ions are injected into the EBIS and charge bred to a charge-to-mass ratio of approximately ¼, and thereafter extracted and injected into a short 3-stage LINAC for acceleration to a few MeV/u. This novel concept, employing a Penning trap to bunch and cool the ions from an on-line mass separator in combination with a charge breeding EBIS, should result in an efficient and compact system. The REXEBIS is based on a 0.5 A electron beam produced in the fringe field of a magnetic solenoid, and compressed to a current density of >200 A/cm2. The 2 T magnetic field is provided by a warm-bore superconducting solenoid, thus giving easy accessibility but no cryogenic pumping. The EBIS is switched between 60 kV (ion injection) and ~20 kV (ion extraction). This thesis presents the design and con...

  2. Modular Battery Charge Controller (United States)

    Button, Robert; Gonzalez, Marcelo


    A new approach to masterless, distributed, digital-charge control for batteries requiring charge control has been developed and implemented. This approach is required in battery chemistries that need cell-level charge control for safety and is characterized by the use of one controller per cell, resulting in redundant sensors for critical components, such as voltage, temperature, and current. The charge controllers in a given battery interact in a masterless fashion for the purpose of cell balancing, charge control, and state-of-charge estimation. This makes the battery system invariably fault-tolerant. The solution to the single-fault failure, due to the use of a single charge controller (CC), was solved by implementing one CC per cell and linking them via an isolated communication bus [e.g., controller area network (CAN)] in a masterless fashion so that the failure of one or more CCs will not impact the remaining functional CCs. Each micro-controller-based CC digitizes the cell voltage (V(sub cell)), two cell temperatures, and the voltage across the switch (V); the latter variable is used in conjunction with V(sub cell) to estimate the bypass current for a given bypass resistor. Furthermore, CC1 digitizes the battery current (I1) and battery voltage (V(sub batt) and CC5 digitizes a second battery current (I2). As a result, redundant readings are taken for temperature, battery current, and battery voltage through the summation of the individual cell voltages given that each CC knows the voltage of the other cells. For the purpose of cell balancing, each CC periodically and independently transmits its cell voltage and stores the received cell voltage of the other cells in an array. The position in the array depends on the identifier (ID) of the transmitting CC. After eight cell voltage receptions, the array is checked to see if one or more cells did not transmit. If one or more transmissions are missing, the missing cell(s) is (are) eliminated from cell

  3. Charge transport by inverse micelles in non-polar media (United States)

    Strubbe, Filip; Neyts, Kristiaan


    Charged inverse micelles play an important role in the electrical charging and the electrodynamics of nonpolar colloidal dispersions relevant for applications such as electronic ink displays and liquid toner printing. This review examines the properties and the behavior of charged inverse micelles in microscale devices in the absence of colloidal particles. It is discussed how charge in nonpolar liquids is stabilized in inverse micelles and how conductivity depends on the inverse micelle size, water content and ionic impurities. Frequently used nonpolar surfactant systems are investigated with emphasis on aerosol-OT (AOT) and poly-isobutylene succinimide (PIBS) in dodecane. Charge generation in the bulk by disproportionation is studied from measurements of conductivity as a function of surfactant concentration and from generation currents in quasi steady-state. When a potential difference is applied, the steady-state situation can show electric field screening or complete charge separation. Different regimes of charge transport are identified when a voltage step is applied. It is shown how the transient and steady-state currents depend on the rate of bulk generation, on insulating layers and on the sticking or non-sticking behavior of charged inverse micelles at interfaces. For the cases of AOT and PIBS in dodecane, the magnitude of the generation rate and the type of interaction at the interface are very different.

  4. Charge orders in organic charge-transfer salts (United States)

    Kaneko, Ryui; Tocchio, Luca F.; Valentí, Roser; Becca, Federico


    Motivated by recent experimental suggestions of charge-order-driven ferroelectricity in organic charge-transfer salts, such as κ-(BEDT-TTF)2Cu[N(CN)2]Cl, we investigate magnetic and charge-ordered phases that emerge in an extended two-orbital Hubbard model on the anisotropic triangular lattice at 3/4 filling. This model takes into account the presence of two organic BEDT-TTF molecules, which form a dimer on each site of the lattice, and includes short-range intramolecular and intermolecular interactions and hoppings. By using variational wave functions and quantum Monte Carlo techniques, we find two polar states with charge disproportionation inside the dimer, hinting to ferroelectricity. These charge-ordered insulating phases are stabilized in the strongly correlated limit and their actual charge pattern is determined by the relative strength of intradimer to interdimer couplings. Our results suggest that ferroelectricity is not driven by magnetism, since these polar phases can be stabilized also without antiferromagnetic order and provide a possible microscopic explanation of the experimental observations. In addition, a conventional dimer-Mott state (with uniform density and antiferromagnetic order) and a nonpolar charge-ordered state (with charge-rich and charge-poor dimers forming a checkerboard pattern) can be stabilized in the strong-coupling regime. Finally, when electron–electron interactions are weak, metallic states appear, with either uniform charge distribution or a peculiar 12-site periodicity that generates honeycomb-like charge order.

  5. The nuclear charge distribution of fission products of thermal neutron induced fission of /sup 235/U

    CERN Document Server

    Wollnik, H; Greif, J; Siegert, G


    Nuclear charge distributions of mass separated light fission products, 79charges using a surface barrier Delta E-silicon detector. After averaging over all energies and ionic charges a very pronounced proton odd-even effect and a smaller neutron odd-even effect is found which results in periodical variations of the average nuclear charge, the variance, the skewness, and the excess. The principles of the variations of the nuclear charge distributions due to varying kinetic energies are discussed. (20 refs).

  6. Fine mist versus large droplets in phase separated manganites

    NARCIS (Netherlands)

    Khomskii, D; Khomskii, L


    The properties of phase-separated systems, e.g., manganites close to a first-order phase transition between charge-ordered insulator and ferromagnetic metal, are usually described by percolation picture. We argue that the correlated occupation of metallic sites leads to the preferential formation of

  7. Electrostatic separation of mineral and vegetal powders with a custom built corona separator: application to biorefinery of rice husk (United States)

    Rajaonarivony, Rova Karine; Rouau, Xavier; Dascalescu, Lucien; Mayer-Laigle, Claire


    In a dry biorefinery scheme, the separation of plant materials into powders rich in the constituents of interest is a crucial step. In recent years, electrostatic separation of agri-resources has sparked a growing interest for its potentialities, but optimization efforts remain to be done especially in case of fine powders. In this study a custom-designed corona-electrostatic separator has been built and its usage for the separation of mineral (ash from rice husk) and vegetal powders (cellulose fibers) with different particle size distributions has been studied. First, the powders have been characterized by their electric charge decay curves and their behaviour on the separator was studied. At a second time, separation tests have been carried out with blends of these two powders, and with native, finely ground, rice husk powder (constituted of both mineral and vegetal particles). In each case, the efficiency of the process was evaluated.

  8. Dipole Moment of a Charged Particle Trapped at the Air-Water Interface. (United States)

    Bossa, Guilherme Volpe; Bohinc, Klemen; Brown, Matthew A; May, Sylvio


    The interaction between two charged particles (such as nanoparticles or colloids) trapped at the air-water interface becomes dipolar at large separations. The corresponding dipole moment can be modeled by considering a single point charge located exactly at the interface, but this model fails to correctly predict the dipole moment's dependence on the salt concentration in the aqueous medium. We extend the single point charge model to two point charges that are separated by a fixed distance and are located at the air-water interface, with one charge being immersed in air and the other in the solvent. The two point charges represent the surface charges at the air-exposed and water-exposed regions of an interface-trapped particle. The two point charges also account for the spatial extension of the particle. On the basis of the Debye-Hückel model, we derive mathematical expressions for the interaction between two pairs of charges and discuss the salt concentration dependence of the dipolar moment at large separations. Our results reveal a residual dipole moment in the limit of large salt content that originates from the charge attached to the air-exposed region of the particle. We discuss nonlinear screening effects and compare the predicted dipolar moments with recent experimental results.

  9. Charge, from EM fields only


    Collins, R. L.


    Consider the electric field E about an electron. Its source has been thought a substance called charge, enclosed within a small volume that defines the size of the electron. Scattering experiments find no size at all. Charge is useful, but mysterious. This study concludes that charge is not real. Useful, but not real. Absent real charge, the electric field must look to a different source. We know another electric field, vxB, not sourced by charge. A simple model of the electron, using EM fiel...

  10. High resolution printing of charge (United States)

    Rogers, John; Park, Jang-Ung


    Provided are methods of printing a pattern of charge on a substrate surface, such as by electrohydrodynamic (e-jet) printing. The methods relate to providing a nozzle containing a printable fluid, providing a substrate having a substrate surface and generating from the nozzle an ejected printable fluid containing net charge. The ejected printable fluid containing net charge is directed to the substrate surface, wherein the net charge does not substantially degrade and the net charge retained on the substrate surface. Also provided are functional devices made by any of the disclosed methods.

  11. Tooth separation potential problems. (United States)

    Vishwanath, A E; Sharmada, B K; Pai, Sandesh S; Nandini, Nelvigi; Roopa, Tubaki


    A displaced orthodontic elastic separator was proposed as being the source of a gingival abscess that progresses to severe bone loss and exfoliation in a healthy adolescent patient with sound periodontal status prior to commencement of orthodontic treatment. After one year of undergoing orthodontic treatment, the patient presented with dull pain and mobility in the left upper permanent molar for which there was no apparent etiology. On clinical examination the patient had gingival inflammation, associated with a deep pocket and severe mobility (Grade III) in relation to the same teeth. Radiographic examination ofan Orthopantomogram (OPG) and IntraOral Periapical Radiograph (IOPAR) revealed a chronic periodontal abscess with severe necrosis of the periodontal ligament and severe alveolar bone loss. On curettage it was found that there was orthodontic elastic separator which was displaced sub gingivally. Active orthodontic forces were temporarily removed and splinting was done. 6 month follow up showed no mobility and significant improvement of alveolar bone height.

  12. HRS Separator HD

    CERN Multimedia


    Footage of the 90 and 60 degree ISOLDE HRS separator magnets in the HRS separator zone. In the two vacuum sectors HRS20 and HRS30 equipment such as the HRS slits SL240, the HRS faraday cup FC300 and wiregrid WG210 can be spotted. Vacuum valves, turbo pumps, beamlines, quadrupoles, water and compressed air connections, DC and signal cabling can be seen throughout the video. The HRS main and user beamgate in the beamline between MAG90 and MAG60 and its switchboxes as well as all vacuum bellows and flanges are shown. Instrumentation such as the HRS scanner unit 482 / 483, the HRS WG470 wiregrid and slits piston can be seen. The different quadrupoles and supports are shown as well as the RILIS guidance tubes and installation at the magnets and the different radiation monitors.

  13. Separation of Climate Signals

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, C; Fodor, I


    Understanding changes in global climate is a challenging scientific problem. Simulated and observed data include signals from many sources, and untangling their respective effects is difficult. In order to make meaningful comparisons between different models, and to understand human effects on global climate, we need to isolate the effects of different sources. Recent eruptions of the El Chichon and Mt. Pinatubo volcanoes coincided with large El Nino and Southern Oscillation (ENSO) events, which complicates the separation of their contributions on global temperatures. Current approaches for separating volcano and ENSO signals in global mean data involve parametric models and iterative techniques [3]. We investigate alternative methods based on principal component analysis (PCA) [2] and independent component analysis (ICA) [1]. Our goal is to determine if such techniques can automatically identify the signals corresponding to the different sources, without relying on parametric models.

  14. Nylon separators. [thermal degradation (United States)

    Lim, H. S.


    A nylon separator was placed in a flooded condition in K0H solution and heated at various high temperatures ranging from 60 C to 110 C. The weight decrease was measured and the molecular weight and decomposition product were analyzed to determine: (1) the effect of K0H concentration on the hydrolysis rate; (2) the effect of K0H concentration on nylon degradation; (3) the activation energy at different K0H concentrations; and (4) the effect of oxygen on nylon degradation. The nylon hydrolysis rate is shown to increase as K0H concentration is decreased 34%, giving a maximum rate at about 16%. Separator hydrolysis is confirmed by molecular weight decrease in age of the batteries, and the reaction of nylon with molecular oxygen is probably negligible, compared to hydrolysis. The extrapolated rate value from the high temperature experiment correlates well with experimental values at 35 degrees.

  15. GPS Separator HD

    CERN Multimedia


    Footage of the 70 degree ISOLDE GPS separator magnet MAG70 as well as the switchyard for the Central Mass and GLM (GPS Low Mass) and GHM (GPS High Mass) beamlines in the GPS separator zone. In the GPS20 vacuum sector equipment such as the long GPS scanner 482 / 483 unit, faraday cup FC 490, vacuum valves and wiregrid piston WG210 and WG475 and radiation monitors can also be seen. Also the RILIS laser guidance and trajectory can be seen, the GPS main beamgate switch box and the actual GLM, GHM and Central Beamline beamgates in the beamlines as well as the first electrostatic quadrupoles for the GPS lines. Close up of the GHM deflector plates motor and connections and the inspection glass at the GHM side of the switchyard.

  16. Learning Separable Filters. (United States)

    Sironi, Amos; Tekin, Bugra; Rigamonti, Roberto; Lepetit, Vincent; Fua, Pascal


    Learning filters to produce sparse image representations in terms of over-complete dictionaries has emerged as a powerful way to create image features for many different purposes. Unfortunately, these filters are usually both numerous and non-separable, making their use computationally expensive. In this paper, we show that such filters can be computed as linear combinations of a smaller number of separable ones, thus greatly reducing the computational complexity at no cost in terms of performance. This makes filter learning approaches practical even for large images or 3D volumes, and we show that we significantly outperform state-of-the-art methods on the curvilinear structure extraction task, in terms of both accuracy and speed. Moreover, our approach is general and can be used on generic convolutional filter banks to reduce the complexity of the feature extraction step.

  17. Medical Separation Among Careerists (United States)


    within their MOS to augment to the career fleet. These selection rates could drop as low as 10% (Lamothe, 2009). Starting in 2009, the program ...regressions, he found that women were 20% more likely to attrite during the Delayed Entry Program , 34% more likely to attrite during Basic Combat Training...such as sexism and tokenism, but these were not specifically applied to separations. 3. Women Serving in Combat Would Strengthen America’s

  18. Innovative Separations Technologies

    Energy Technology Data Exchange (ETDEWEB)

    J. Tripp; N. Soelberg; R. Wigeland


    Reprocessing used nuclear fuel (UNF) is a multi-faceted problem involving chemistry, material properties, and engineering. Technology options are available to meet a variety of processing goals. A decision about which reprocessing method is best depends significantly on the process attributes considered to be a priority. New methods of reprocessing that could provide advantages over the aqueous Plutonium Uranium Reduction Extraction (PUREX) and Uranium Extraction + (UREX+) processes, electrochemical, and other approaches are under investigation in the Fuel Cycle Research and Development (FCR&D) Separations Campaign. In an attempt to develop a revolutionary approach to UNF recycle that may have more favorable characteristics than existing technologies, five innovative separations projects have been initiated. These include: (1) Nitrogen Trifluoride for UNF Processing; (2) Reactive Fluoride Gas (SF6) for UNF Processing; (3) Dry Head-end Nitration Processing; (4) Chlorination Processing of UNF; and (5) Enhanced Oxidation/Chlorination Processing of UNF. This report provides a description of the proposed processes, explores how they fit into the Modified Open Cycle (MOC) and Full Recycle (FR) fuel cycles, and identifies performance differences when compared to 'reference' advanced aqueous and fluoride volatility separations cases. To be able to highlight the key changes to the reference case, general background on advanced aqueous solvent extraction, advanced oxidative processes (e.g., volumetric oxidation, or 'voloxidation,' which is high temperature reaction of oxide UNF with oxygen, or modified using other oxidizing and reducing gases), and fluorination and chlorination processes is provided.

  19. Colour Separation and Aversion

    Directory of Open Access Journals (Sweden)

    Sarah M Haigh


    Full Text Available Aversion to achromatic patterns is well documented but relatively little is known about discomfort from chromatic patterns. Large colour differences are uncommon in the natural environment and deviation from natural statistics makes images uncomfortable (Fernandez and Wilkins 2008, Perception, 37(7, 1098–113; Juricevic et al 2010, Perception, 39(7, 884–899. We report twelve studies documenting a linear increase in aversion to chromatic square-wave gratings as a function of the separation in UCS chromaticity between the component bars, independent of their luminance contrast. Two possible explanations for the aversion were investigated: (1 accommodative response, or (2 cortical metabolic demand. We found no correlation between chromaticity separation and accommodative lag or variance in lag, measured using an open-field autorefractor. However, near infrared spectroscopy of the occipital cortex revealed a larger oxyhaemoglobin response to patterns with large chromaticity separation. The aversion may be cortical in origin and does not appear to be due to accommodation.

  20. Taking control of charge transfer : strategic design for solar cells

    NARCIS (Netherlands)

    Monti, Adriano


    The thesis is focused on the investigation of the electron transfer mechanisms leading to solar fuel production and to the identification of engineering principles that can be used to design materials able to improve charge separation. Molecular systems composed of three or more subunits arranged


    Energy Technology Data Exchange (ETDEWEB)

    John M. Stencel


    The technical feasibility of separating mineral matter and pyrite from coal as it is transported from pulverizers to burners in pulverized coal combustion units is examined. The charge imparted on coal during pulverization and transport to pulverized coal (PC) burners in a utility boiler is quantified. In addition to field charge measurements, an existing computational model is extended to numerically simulate charged particle motion in a turbulent gas through coal transport pipes and triboelectrostatic separation zone. Results from the field tests and numerical modeling are employed in a conceptual design and a 4--40 kg/hr laboratory-scale separator is constructed and tested. This laboratory unit is used to quantify the magnitude and differential charge imparted on coals during pulverization and transport typical in utility PC units. An electrostatic separator, designed for in-line operation between pulverizers and PC boilers, will be used to clean prepulverized coals. Theoretical and experimental data are to be used in preparing a preliminary and conceptual design for a 15 ton/hr, in-line, electrostatic coal cleaning device. Finally, the economic potential for applications to PC units is assessed.

  2. Status of charge breeding with electron cyclotron resonance ion sources (invited)

    CERN Document Server

    Lamy, T; Sortais, P; Thuillier, T; 10.1063/1.2149300


    Due to the production methods of exotic nuclei, an efficient acceleration of radioactive ion beams needs charge breeding of weakly charged ions. The upgrade of existing isotope separator on-line facilities (TRIUMF-isotope separation and acceleration, CERN-isotope separation on-line detector, etc.) or the development of projects for the acceleration of radioactive ion beams (GANIL-SPIRAL2, MAFF, EURISOL, etc.) requires charge breeders with high efficiency, fast charge breeding time, low background levels, and high intensity acceptance either in continuous or in pulsed mode. The optimization of these parameters is a challenge for the electron cyclotron resonance (ECR) community and is useful to get a better understanding of plasma physics in ECR ion sources (ECRISs). The ECR charge breeding technique has been developed for more than ten years at LPSC (former ISN) Grenoble, typical 1+rightward arrown+ efficiencies are in the 3%-10% range depending on the nature of the incoming beam (metallic, alkaline, and gaseo...

  3. Design of the SUPERB Recoil Separator (United States)

    Jackson, Zachary; Carpenter, Lisa; Amthor, Matt


    The reaccelerator ReA12 upgrade planned at the National Superconducting Cyclotron Lab (NSCL) at Michigan State University will produce higher energy rare isotope beams close to the neutron and proton drip lines. We present one option for the recoil separator which aims to take full advantage of the new capabilities of ReA12 in studying rare isotopes. The Separator for Unique Products of Experiments with Radioactive Beams (SUPERB), patterned after the second half of the Super Separator-Spectrometer (S3) currently under construction at the Grand Accélérateur National d'Ions Lourds (GANIL). This design includes both electric and magnetic dipoles and this will allow physical separation by mass-to-charge ratio (m/q) with a maximum solid angle of 26 msr and a maximum magnetic rigidity of 1.44 Tm. This design also allows for flexibility of optical modes. Both large acceptance and unit magnification modes will be presented. Also, a fully magnetic configuration is considered that would eliminate the expected electric rigidity limit of 10 MV and increase the maximum magnetic rigidity to 1.92 Tm. We will present optical designs and simulations of SUBERB developed in the code COSY Infinity including a first order system and a higher order Monte Carlo calculation simulating 100Sn production. This research was funded by the NSF REU program, grant PHY-1165694 with additional support from the DoD ASSURE program.

  4. Electronic phase separation and high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kivelson, S.A. [Univ. of California, Los Angeles, CA (United States). Dept. of Physics; Emery, V.J. [Brookhaven National Lab., Upton, NY (United States)


    The authors review the extensive evidence from model calculations that neutral holes in an antiferromagnet separate into hole-rich and hole-poor phases. All known solvable limits of models of holes in a Heisenberg antiferromagnet exhibit this behavior. The authors show that when the phase separation is frustrated by the introduction of long-range Coulomb interactions, the typical consequence is either a modulated (charge density wave) state or a superconducting phase. The authors then review some of the strong experimental evidence supporting an electronically-driven phase separation of the holes in the cuprate superconductors and the related Ni oxides. Finally, the authors argue that frustrated phase separation in these materials can account for many of the anomalous normal state properties of the high temperature superconductors and provide the mechanism of superconductivity. In particular, it is shown that the T-linear resistivity of the normal state is a paraconductivity associated with a novel composite pairing, although the ordered superconducting state is more conventional.

  5. Charged Galileon black holes

    Energy Technology Data Exchange (ETDEWEB)

    Babichev, Eugeny; Charmousis, Christos [Laboratoire de Physique Théorique (LPT), Univ. Paris-Sud, CNRS UMR 8627, F-91405 Orsay (France); Hassaine, Mokhtar, E-mail:, E-mail:, E-mail: [Instituto de Matemática y Física, Universidad de Talca, Casilla 747, Talca (Chile)


    We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.

  6. Annealed Scaling for a Charged Polymer

    Energy Technology Data Exchange (ETDEWEB)

    Caravenna, F., E-mail: [Università degli Studi di Milano-Bicocca, Dipartimento di Matematica e Applicazioni (Italy); Hollander, F. den, E-mail: [Leiden University, Mathematical Institute (Netherlands); Pétrélis, N., E-mail: [Université de Nantes, Laboratoire de Mathématiques Jean Leray UMR 6629 (France); Poisat, J., E-mail: [Université Paris-Dauphine, PSL Research University, CEREMADE, UMR 7534 (France)


    This paper studies an undirected polymer chain living on the one-dimensional integer lattice and carrying i.i.d. random charges. Each self-intersection of the polymer chain contributes to the interaction Hamiltonian an energy that is equal to the product of the charges of the two monomers that meet. The joint probability distribution for the polymer chain and the charges is given by the Gibbs distribution associated with the interaction Hamiltonian. The focus is on the annealed free energy per monomer in the limit as the length of the polymer chain tends to infinity. We derive a spectral representation for the free energy and use this to prove that there is a critical curve in the parameter plane of charge bias versus inverse temperature separating a ballistic phase from a subballistic phase. We show that the phase transition is first order. We prove large deviation principles for the laws of the empirical speed and the empirical charge, and derive a spectral representation for the associated rate functions. Interestingly, in both phases both rate functions exhibit flat pieces, which correspond to an inhomogeneous strategy for the polymer to realise a large deviation. The large deviation principles in turn lead to laws of large numbers and central limit theorems. We identify the scaling behaviour of the critical curve for small and for large charge bias. In addition, we identify the scaling behaviour of the free energy for small charge bias and small inverse temperature. Both are linked to an associated Sturm-Liouville eigenvalue problem. A key tool in our analysis is the Ray-Knight formula for the local times of the one-dimensional simple random walk. This formula is exploited to derive a closed form expression for the generating function of the annealed partition function, and for several related quantities. This expression in turn serves as the starting point for the derivation of the spectral representation for the free energy, and for the scaling theorems

  7. Experimental Study of Separate Type Thermosyphon (United States)

    Hirashima, Masao; Kawahata, Kenya; Negishi, Kanji

    The passages of vapor flow and the returning liquid flow are perfectly partitioned in a separate type thermosyphon. Therefore the flooding limit can be eliminated and practicability based on its construction is highly evaluated. The carry-over of the liquid into the condensing section accompanied with the rising vapor flow should be avoided in the separate type thermosyphon, since it causes to decrease the heat transfer coefficient on the heat transfer surface in the condenser. In the present work, the effect of liquid level, the heat input into the evaporating section, the charging rate of the liquid, and the dimension of the adiabatic section supposed on the generation of carry-over were studied experimentally. The frequency of the bumping and the velocity of the vapor in the adiabatic section were examined as the function of the termination of the carry-over. The experimental correlation representing the relation among the elapsed time, the liquid temperature and the charging rate of the liquid were also derived.

  8. Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems (United States)

    Tuffner, Francis K [Richland, WA; Kintner-Meyer, Michael C. W. [Richland, WA; Hammerstrom, Donald J [West Richland, WA; Pratt, Richard M [Richland, WA


    Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems. According to one aspect, a battery charging control method includes accessing information regarding a presence of at least one of a surplus and a deficiency of electrical energy upon an electrical power distribution system at a plurality of different moments in time, and using the information, controlling an adjustment of an amount of the electrical energy provided from the electrical power distribution system to a rechargeable battery to charge the rechargeable battery.

  9. Combined electrophoretic-separation and electrospray method and system (United States)

    Smith, R.D.; Olivares, J.A.


    A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary zone electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5--100 kVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., [+-]2--8 kVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit. 10 figs.


    Wilhelm, H.A.; Foos, R.A.


    The usual method for the separation of tantalum and niobium consists of a selective solvent extraction from an aqueous hydrofluoric acid solution of the metals. A difficulty encountered in this process is the fact that the corrosion problems associated with hydrofluoric acid are serious. It has been found that the corrosion caused by the hydrofluoric acid may be substantially reduced by adding to the acidic solution an amine, such as phenyl diethanolamine or aniline, and adjusting pH value to between 4 and 6.


    Maddock, A.G.; Smith, F.


    A method is described for separating plutonium from uranium and fission products by treating a nitrate solution of fission products, uranium, and hexavalent plutonium with a relatively water-insoluble fluoride to adsorb fission products on the fluoride, treating the residual solution with a reducing agent for plutonium to reduce its valence to four and less, treating the reduced plutonium solution with a relatively insoluble fluoride to adsorb the plutonium on the fluoride, removing the solution, and subsequently treating the fluoride with its adsorbed plutonium with a concentrated aqueous solution of at least one of a group consisting of aluminum nitrate, ferric nitrate, and manganous nitrate to remove the plutonium from the fluoride.

  12. Charge Storage, Conductivity and Charge Profiles of Insulators as Related to Spacecraft Charging (United States)

    Dennison, J. R.; Swaminathan, Prasanna; Frederickson, A. R.


    Dissipation of charges built up near the surface of insulators due to space environment interaction is central to understanding spacecraft charging. Conductivity of insulating materials is key to determine how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. To understand these processes requires knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and charge transport within the insulator, and how the profile of trapped charge affects the transport and emission of charges from insulators. One must consider generation of mobile electrons and holes, their trapping, thermal de-trapping, mobility and recombination. Conductivity is more appropriately measured for spacecraft charging applications as the "decay" of charge deposited on the surface of an insulator, rather than by flow of current across two electrodes around the sample. We have found that conductivity determined from charge storage decay methods is 102 to 104 smaller than values obtained from classical ASTM and IEC methods for a variety of thin film insulating samples. For typical spacecraft charging conditions, classical conductivity predicts decay times on the order of minutes to hours (less than typical orbit periods); however, the higher charge storage conductivities predict decay times on the order of weeks to months leading to accumulation of charge with subsequent orbits. We found experimental evidence that penetration profiles of radiation and light are exceedingly important, and that internal electric fields due to charge profiles and high-field conduction by trapped electrons must be considered for space applications. We have also studied whether the decay constants depend on incident voltage and flux or on internal charge distributions and electric fields; light-activated discharge of surface charge to distinguish among differing charge trapping centers; and radiation-induced conductivity. Our

  13. Understanding the Linkage between Charging Network Coverage and Charging Opportunity

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changzheng [ORNL; Lin, Zhenhong [ORNL; Kontou, Eleftheria [University of Florida, Gainesville; Wu, Xing [Lamar University


    Using GPS-based travel survey data, this paper estimates the relationship between public charging network coverage and charging opportunity, defined as the probability of being able to access public charging for a driver at one of his/her stops or at one travel day. Understanding this relationship is of important interests to the electric vehicle industry and government in determining appropriate charging infrastructure deployment level and estimating the impact of public charging on market adoption of electric vehicles. The analysis finds that drivers trip destinations concentrate on a few popular places. If top 1% of most popular places are installed with public chargers, on average, drivers will be able to access public charging at 20% of all their stops and 1/3 of their travel days; If 20% of most popular places are installed with public chargers, drivers will be able to access public charging at 89% of all their stops and 94% of their travel days. These findings are encouraging, implying charging network can be efficiently designed by concentrating at a few popular places while still providing a high level of charging opportunity.

  14. Controlling Charge and Energy Transfer Processes in Artificial Photosynthesis : From Picosecond to Millisecond Dynamics


    Borgström, Magnus


    This thesis describes an interdisciplinary project, where the aim is to mimic the initial reactions in photosynthesis. In photosynthesis, the absorption of light is followed by the formation of charge-separated states. The energy stored in these charge-separated states is further used for the oxidation of water and reduction of carbon dioxide. In this thesis the photo-induced processes in a range of supramolecular complexes have been investigated with time resolved spectroscopic techniques. T...

  15. Engine Tune-up Service. Unit 2: Charging System. Posttests. Automotive Mechanics Curriculum. (United States)

    Richardson, Roger L.; Bacon, E. Miles

    This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 2, Charging System, available separately as CE 031 208. Focus of the posttest is on the testing of the charging system. One multiple choice posttest is provided, that covers the three performance objectives contained in the unit. (No answer key is…

  16. Charge Transport in Conjugated Block Copolymers (United States)

    Smith, Brandon; Le, Thinh; Lee, Youngmin; Gomez, Enrique

    Interest in conjugated block copolymers for high performance organic photovoltaic applications has increased considerably in recent years. Polymer/fullerene mixtures for conventional bulk heterojunction devices, such as P3HT:PCBM, are severely limited in control over interfaces and domain length scales. In contrast, microphase separated block copolymers self-assemble to form lamellar morphologies with alternating electron donor and acceptor domains, thereby maximizing electronic coupling and local order at interfaces. Efficiencies as high as 3% have been reported in solar cells for one block copolymer, P3HT-PFTBT, but the details concerning charge transport within copolymers have not been explored. To fill this gap, we probed the transport characteristics with thin-film transistors. Excellent charge mobility values for electron transport have been observed on aluminum source and drain contacts in a bottom gate, bottom contact transistor configuration. Evidence of high mobility in ordered PFTBT phases has also been obtained following thermal annealing. The insights gleaned from our investigation serve as useful guideposts, revealing the significance of the interplay between charge mobility, interfacial order, and optimal domain size in organic block copolymer semiconductors.

  17. SEP ionic charge states in ESP and impulsive events (United States)

    Popecki, M.; Moebius, E.; Galvin, A.; Kistler, L.; Kucharek, H.; Klecker, B.

    The SEPICA instrument on the Advanced Composition Explorer (ACE) spacecraft has measured ionic charge states of solar energetic particles (SEPs) from late 1997 through 2000. Charge state measurements provide insights about the acceleration and propa- gation history of SEPs. In impulsive events, SEP charge states provide information about the flare environment, where source heating and collisions are important. In in- terplanetary shock events, SEP charge states are diagnostics of the rigidity-dependent acceleration process and particle seed populations. For example, 3He enrichment has been observed in some events with a local shock passage (Desai et al., 2001). An en- hancement in high charge state Fe has also been observed in these events (Popecki et al., 2001). This suggests that the seed population for the interplanetary shock con- tained ions previously accelerated in flares. SEP charge states from impulsive events will be compared to those from events with a local shock passage (ESP events). In addition, the ESP events wil be separated into those with and without 3He enrichment. Results will be presented in the context of mission-integrated ionic charge state distributions for each species.

  18. Battery charging stations

    Energy Technology Data Exchange (ETDEWEB)

    Bergey, M.


    This paper discusses the concept of battery charging stations (BCSs), designed to service rural owners of battery power sources. Many such power sources now are transported to urban areas for recharging. A BCS provides the opportunity to locate these facilities closer to the user, is often powered by renewable sources, or hybrid systems, takes advantage of economies of scale, and has the potential to provide lower cost of service, better service, and better cost recovery than other rural electrification programs. Typical systems discussed can service 200 to 1200 people, and consist of stations powered by photovoltaics, wind/PV, wind/diesel, or diesel only. Examples of installed systems are presented, followed by cost figures, economic analysis, and typical system design and performance numbers.

  19. Printed Spacecraft Separation System

    Energy Technology Data Exchange (ETDEWEB)

    Dehoff, Ryan R [ORNL; Holmans, Walter [Planetary Systems Corporation


    In this project Planetary Systems Corporation proposed utilizing additive manufacturing (3D printing) to manufacture a titanium spacecraft separation system for commercial and US government customers to realize a 90% reduction in the cost and energy. These savings were demonstrated via “printing-in” many of the parts and sub-assemblies into one part, thus greatly reducing the labor associated with design, procurement, assembly and calibration of mechanisms. Planetary Systems Corporation redesigned several of the components of the separation system based on additive manufacturing principles including geometric flexibility and the ability to fabricate complex designs, ability to combine multiple parts of an assembly into a single component, and the ability to optimize design for specific mechanical property targets. Shock absorption was specifically targeted and requirements were established to attenuate damage to the Lightband system from shock of initiation. Planetary Systems Corporation redesigned components based on these requirements and sent the designs to Oak Ridge National Laboratory to be printed. ORNL printed the parts using the Arcam electron beam melting technology based on the desire for the parts to be fabricated from Ti-6Al-4V based on the weight and mechanical performance of the material. A second set of components was fabricated from stainless steel material on the Renishaw laser powder bed technology due to the improved geometric accuracy, surface finish, and wear resistance of the material. Planetary Systems Corporation evaluated these components and determined that 3D printing is potentially a viable method for achieving significant cost and savings metrics.

  20. Virus separation using membranes. (United States)

    Grein, Tanja A; Michalsky, Ronald; Czermak, Peter


    Industrial manufacturing of cell culture-derived viruses or virus-like particles for gene therapy or vaccine production are complex multistep processes. In addition to the bioreactor, such processes require a multitude of downstream unit operations for product separation, concentration, or purification. Similarly, before a biopharmaceutical product can enter the market, removal or inactivation of potential viral contamination has to be demonstrated. Given the complexity of biological solutions and the high standards on composition and purity of biopharmaceuticals, downstream processing is the bottleneck in many biotechnological production trains. Membrane-based filtration can be an economically attractive and efficient technology for virus separation. Viral clearance, for instance, of up to seven orders of magnitude has been reported for state of the art polymeric membranes under best conditions.This chapter summarizes the fundamentals of virus ultrafiltration, diafiltration, or purification with adsorptive membranes. In lieu of an impractical universally applicable protocol for virus filtration, application of these principles is demonstrated with two examples. The chapter provides detailed methods for production, concentration, purification, and removal of a rod-shaped baculovirus (Autographa californica M nucleopolyhedrovirus, about 40 × 300 nm in size, a potential vector for gene therapy, and an industrially important protein expression system) or a spherical parvovirus (minute virus of mice, 22-26 nm in size, a model virus for virus clearance validation studies).

  1. Comparison between students and residents on determinants of willingness to separate waste and waste separation behaviour in Zhengzhou, China. (United States)

    Dai, Xiaoping; Han, Yuping; Zhang, Xiaohong; Hu, Wei; Huang, Liangji; Duan, Wenpei; Li, Siyi; Liu, Xiaolu; Wang, Qian


    A better understanding of willingness to separate waste and waste separation behaviour can aid the design and improvement of waste management policies. Based on the intercept questionnaire survey data of undergraduate students and residents in Zhengzhou City of China, this article compared factors affecting the willingness and behaviour of students and residents to participate in waste separation using two binary logistic regression models. Improvement opportunities for waste separation were also discussed. Binary logistic regression results indicate that knowledge of and attitude to waste separation and acceptance of waste education significantly affect the willingness of undergraduate students to separate waste, and demographic factors, such as gender, age, education level, and income, significantly affect the willingness of residents to do so. Presence of waste-specific bins and attitude to waste separation are drivers of waste separation behaviour for both students and residents. Improved education about waste separation and facilities are effective to stimulate waste separation, and charging on unsorted waste may be an effective way to improve it in Zhengzhou.

  2. 12 CFR 226.4 - Finance charge. (United States)


    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Finance charge. 226.4 Section 226.4 Banks and... LENDING (REGULATION Z) General § 226.4 Finance charge. (a) Definition. The finance charge is the cost of...) Charges by third parties. The finance charge includes fees and amounts charged by someone other than the...

  3. The surface charge of trypanosomatids

    Directory of Open Access Journals (Sweden)



    Full Text Available The surface charge of trypanosomatids was evaluated by means of the binding of cationic particles, as visualized by electron microscopy and by direct measurements of the electrophoretic mobility of cells. The results obtained indicate that most of the trypanosomatids exhibit a negatively charged surface whose value is species specific and varies according to the developmental stages. Sialic acids associated with glycoproteins, glycolipids and phosphate groups are the major components responsible for the net negative surface charge of the trypanosomatids.

  4. Progress Towards Charge Exchange Cross-Sections with Highly Charged Ions: Computation and Experiment (United States)

    Bromley, Steven James

    This thesis is a summary of the computational and experimental progress towards measuring the charge exchange cross-section of highly charged ions (HCIs). Electronic structure calculations were carried out for the molecular ion LiHe+ using NWChem on the Clemson University Palmetto Cluster. Potential energy surfaces for 40 electronic states are presented. The electronic configurations of the six lowest states have been identified by their energies in the separate atom limit, which deviate from experimental values by at most 1.2%. Future work will investigate higher charge states of LiHe and the interaction between low-Z HCIs and neutral gases. Two experimental apparatus were designed and constructed for experiments with HCIs. To aid in the detection of trapped HCIs, a time-of-flight mass spectrometer for radial extraction from Paul traps was constructed and tested using a Mg + source. Lastly, a gas cell was designed and constructed for charge exchange cross-section measurements using HCIs produced in the Clemson University Electron Beam Ion Trap (CUEBIT).

  5. Fractional Charge Definitions and Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Goldhaber, A.S.


    Fractional charge is known through theoretical and experimental discoveries of isolable objects carrying fractions of familiar charge units--electric charge Q, spin S, and the difference of baryon and lepton numbers B-L. With a few simple assumptions all these effects may be described using a generalized version of charge renormalization for locally conserved charges, in which medium correlations yield familiar adiabatic, continuous renormalization, or sometimes nonadiabatic, discrete renormalization. Fractional charges may be carried by fundamental particles or fundamental solitons. Either picture works for the simplest fractional-quantum-Hall-effect quasiholes, though the particle description is far more general. The only known fundamental solitons in three or fewer space dimensions d are the kink (d = 1), the vortex (d = 2), and the magnetic monopole (d = 3). Further, for a charge not intrinsically coupled to the topological charge of a soliton, only the kink and the monopole may carry fractional values. The same reasoning enforces fractional values of B-L for electrically charged elementary particles.

  6. LISA and LISA Pathfinder charging

    Energy Technology Data Exchange (ETDEWEB)

    Sumner, T J; Shaul, D N A; Schulte, M O; Waschke, S; Hollington, D; Araujo, H, E-mail: [Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)


    Charging of the isolated proof masses which form the mirrors defining the path lengths for the LISA and LISA Pathfinder (LISAPF) interferometers turns out to be one of the limiting sources of spurious noise for both missions. An overview of the charging effects and processes will be given which set the scale of the charge-induced noise contributions within the overall LISA sensitivity budget. The current charge control hardware and operations for LISAPF will be described, followed by a forward look to the necessary further developments needed for LISA.

  7. Charge distribution of d*(2380 ) (United States)

    Dong, Yubing; Huang, Fei; Shen, Pengnian; Zhang, Zongye


    Based on a chiral constituent quark model, we calculate the charge distributions of d*(2380 ). We consider the existence of two different interpretations of the d*: a compact structure in the two-coupled-channel (Δ Δ +C C ) approximation, and a resonant structure of D12π . We calculate the charge distribution of the d* with a compact structure, and we also roughly estimate the charge distribution for a D12π structure on the same base. The result shows that there is a remarkable difference in the charge distributions of the two structural pictures. Therefore, we expect that future experiments may provide a clear signal for the d* structure.

  8. Charged Polaritons with Spin 1

    Directory of Open Access Journals (Sweden)

    Samoilov V.


    Full Text Available We present a new model for metal which is based on the stimulated vibration of independent charged Fermi-ions, representing as independent harmonic oscillators with natural frequencies, under action of longitudinal and transverse elastic waves. Due to application of the elastic wave-particle principle and ion-wave dualities, we predict the existence of two types of charged Polaritons with spin 1 which are induced by longitudinal and transverse elastic fields. As result of presented theory, at small wavenumbers, these charged polaritons represent charged phonons.

  9. Low-charge-state linac

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, K.W.; Kim, J.W.


    A design is being developed for a low-charge-state linac suitable for injecting ATLAS with a low-charge-state, radioactive beam. Initial work indicates that the existing ATLAS interdigital superconducting accelerating structures, together with the superconducting quadrupole transverse focussing element discussed above, provides a basis for a high-performance low-charge-state linac. The initial 2 or 3 MV of such a linac could be based on a normally-conducting, low-frequency RFQ, possibly combined with 24-MHz superconducting interdigital structures. Beam dynamics studies of the whole low-charge-state post-accelerator section were carried out in early FY 1995.

  10. Charge Pricing Optimization Model for Private Charging Piles in Beijing

    Directory of Open Access Journals (Sweden)

    Xingping Zhang


    Full Text Available This paper develops a charge pricing model for private charging piles (PCPs by considering the environmental and economic effects of private electric vehicle (PEV charging energy sources and the impact of PCP charging load on the total load. This model simulates users’ responses to different combinations of peak-valley prices based on the charging power of PCPs and user charging transfer rate. According to the regional power structure, it calculates the real-time coal consumption, carbon dioxide emissions reduction, and power generation costs of PEVs on the power generation side. The empirical results demonstrate that the proposed peak-valley time-of-use charging price can not only minimize the peak-valley difference of the total load but also improve the environmental effects of PEVs and the economic income of the power system. The sensitivity analysis shows that the load-shifting effect of PCPs will be more obvious when magnifying the number of PEVs by using the proposed charging price. The case study indicates that the proposed peak, average, and valley price in Beijing should be 1.8, 1, and 0.4 yuan/kWh, which can promote the large-scale adoption of PEVs.

  11. Charge migration and charge transfer in molecular systems

    Directory of Open Access Journals (Sweden)

    Hans Jakob Wörner


    Full Text Available The transfer of charge at the molecular level plays a fundamental role in many areas of chemistry, physics, biology and materials science. Today, more than 60 years after the seminal work of R. A. Marcus, charge transfer is still a very active field of research. An important recent impetus comes from the ability to resolve ever faster temporal events, down to the attosecond time scale. Such a high temporal resolution now offers the possibility to unravel the most elementary quantum dynamics of both electrons and nuclei that participate in the complex process of charge transfer. This review covers recent research that addresses the following questions. Can we reconstruct the migration of charge across a molecule on the atomic length and electronic time scales? Can we use strong laser fields to control charge migration? Can we temporally resolve and understand intramolecular charge transfer in dissociative ionization of small molecules, in transition-metal complexes and in conjugated polymers? Can we tailor molecular systems towards specific charge-transfer processes? What are the time scales of the elementary steps of charge transfer in liquids and nanoparticles? Important new insights into each of these topics, obtained from state-of-the-art ultrafast spectroscopy and/or theoretical methods, are summarized in this review.

  12. Long-range interaction between heterogeneously charged membranes. (United States)

    Jho, Y S; Brewster, R; Safran, S A; Pincus, P A


    Despite their neutrality, surfaces or membranes with equal amounts of positive and negative charge can exhibit long-range electrostatic interactions if the surface charge is heterogeneous; this can happen when the surface charges form finite-size domain structures. These domains can be formed in lipid membranes where the balance of the different ranges of strong but short-ranged hydrophobic interactions and longer-ranged electrostatic repulsion result in a finite, stable domain size. If the domain size is large enough, oppositely charged domains in two opposing surfaces or membranes can be strongly correlated by the electrostatic interactions; these correlations give rise to an attractive interaction of the two membranes or surfaces over separations on the order of the domain size. We use numerical simulations to demonstrate the existence of strong attractions at separations of tens of nanometers. Large line tensions result in larger domains but also increase the charge density within the domain. This promotes correlations and, as a result, increases the intermembrane attraction. On the other hand, increasing the salt concentration increases both the domain size and degree of domain anticorrelation, but the interactions are ultimately reduced due to increased screening. The result is a decrease in the net attraction as salt concentration is increased. © 2011 American Chemical Society

  13. Design Tools for FRIB Fragment Separators (United States)

    Bandura, Laura


    A key component of the Facility for Rare Isotope Beams, FRIB will be the in-flight fragment separator used to select and purify the isotope of interest for experiments. In order to simulate this process, we have developed a hybrid map-Monte Carlo code based on the ion optics code COSY INFINITY that accurately models fragment production and atomic processes. The code COSY INFINTIY uses powerful differential algebraic methods for computing the dynamics of the beam in the fragment separator. Ion production and atomic processes have been added to COSY to calculate beam-material interactions. The code tracks the fragmentation and fission of the beam in target and absorber material while computing energy loss and energy and angular straggling as well as charge state evolution of the beam by implementing auxiliary codes such as ATIMA and GLOBAL. EPAX has been utilized to return the cross sections of fragmentation products. The hybrid map-Monte Carlo code extensions added to COSY provide an integrated beam dynamics-nuclear processes design optimization and simulation framework that is efficient and accurate. The code may be used to optimize any fragment separator system for the selection of any rare isotope.

  14. Ion and water transport in charge-modified graphene nanopores (United States)

    Qiu, Ying-Hua; Li, Kun; Chen, Wei-Yu; Si, Wei; Tan, Qi-Yan; Chen, Yun-Fei


    Porous graphene has a high mechanical strength and an atomic-layer thickness that makes it a promising material for material separation and biomolecule sensing. Electrostatic interactions between charges in aqueous solutions are a type of strong long-range interaction that may greatly influence fluid transport through nanopores. In this study, molecular dynamic simulations were conducted to investigate ion and water transport through 1.05-nm diameter monolayer graphene nanopores, with their edges charge-modified. Our results indicated that these nanopores are selective to counterions when they are charged. As the charge amount increases, the total ionic currents show an increase-decrease profile while the co-ion currents monotonically decrease. The co-ion rejection can reach 76.5% and 90.2% when the nanopores are negatively and positively charged, respectively. The Cl- ion current increases and reaches a plateau, and the Na+ current decreases as the charge amount increases in systems in which Na+ ions act as counterions. In addition, charge modification can enhance water transport through nanopores. This is mainly due to the ion selectivity of the nanopores. Notably, positive charges on the pore edges facilitate water transport much more strongly than negative charges. Project supported by the National Basic Research Program of China (Grant Nos. 2011CB707601 and 2011CB707605), the National Natural Science Foundation of China (Grant No. 50925519), the Fundamental Research Funds for the Central Universities, Funding of Jiangsu Provincial Innovation Program for Graduate Education, China (Grant No. CXZZ13_0087), and the Scientific Research Foundation of Graduate School of Southeast University (Grant No. YBJJ 1322).

  15. Charge Carrier Dynamics at Silver Nanocluster-Molecular Acceptor Interfaces

    KAUST Repository

    Almansaf, Abdulkhaleq


    A fundamental understanding of interfacial charge transfer at donor-acceptor interfaces is very crucial as it is considered among the most important dynamical processes for optimizing performance in many light harvesting systems, including photovoltaics and photo-catalysis. In general, the photo-generated singlet excitons in photoactive materials exhibit very short lifetimes because of their dipole-allowed spin radiative decay and short diffusion lengths. In contrast, the radiative decay of triplet excitons is dipole forbidden; therefore, their lifetimes are considerably longer. The discussion in this thesis primarily focuses on the relevant parameters that are involved in charge separation (CS), charge transfer (CT), intersystem crossing (ISC) rate, triplet state lifetime, and carrier recombination (CR) at silver nanocluster (NCs) molecular-acceptors interfaces. A combination of steady-state and femto- and nanosecond broadband transient absorption spectroscopies were used to investigate the charge carrier dynamics in various donor-acceptor systems. Additionally, this thesis was prolonged to investigate some important factors that influence the charge carrier dynamics in Ag29 silver NCs donor-acceptor systems, such as the metal doping and chemical structure of the nanocluster and molecular acceptors. Interestingly, clear correlations between the steady-state measurements and timeresolved spectroscopy results are found. In the first study, we have investigated the interfacial charge transfer dynamics in positively charged meso units of 5, 10, 15, 20-tetra (1- methyl-4-pyridino)-porphyrin tetra (p-toluene sulfonate) (TMPyP) and neutral charged 5, 10, 15, 20-tetra (4-pyridyl)-porphyrin (TPyP), with negatively charged undoped and gold (Au)- doped silver Ag29 NCs. Moreover, this study showed the impact of Au doping on the charge carrier dynamics of the system. In the second study, we have investigated the interfacial charge transfer dynamics in [Pt2 Ag23 Cl7 (PPh3

  16. Quantum charged rigid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail:, E-mail:, E-mail: [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)


    The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.

  17. Searches for charged Higgs bosons

    CERN Document Server

    Ellert, M


    The results of the searches for charged Higgs bosons at the four experiments at the LEP collider have been combined in order derive an exclusion limit using the largest possible data sample. This combined analysis excludes the existence of charged Higgs bosons with masses lower than 78.6 GeV/c/sup 2/ at 95% confidence level. (5 refs).

  18. Point Charges and Polygonal Linkages

    NARCIS (Netherlands)

    Khimshiashvili, Giorgi; Panina, Gaiane; Siersma, Dirk; Zolotov, Vladimir

    We investigate the critical points of Coulomb potential of point charges placed at the vertices of a planar polygonal linkage. It is shown that, for a collection of positive charges on a pentagonal linkage, there is a unique critical point in the set of convex configurations which is the point of

  19. Charged-lepton flavour physics

    Indian Academy of Sciences (India)

    Abstract. This write-up on a talk at the 2011 Lepton–Photon symposium in Mumbai, India, summarizes recent results in the charged-lepton flavour sector. Searches for charged-lepton flavour violation, lepton electric dipole moments and flavour-conserving CP violation are reviewed here. Recent progress in -lepton physics ...

  20. Solvent-Dependent Delamination, Restacking, and Ferroelectric Behavior in a New Charge-Separated Layered Compound: [NH4 ][Ag3 (C9 H5 NO4 S)2 (C13 H14 N2 )2 ]⋅8 H2 O. (United States)

    Sushrutha, Sringeri Ramesh; Mohana, Shivanna; Pal, Somnath; Natarajan, Srinivasan


    A new anionic coordination polymer, [NH4 ][Ag3 (C9 H5 NO4 S)2 (C13 H14 N2 )2 ]⋅8 H2 O, with a two-dimensional structure, has been synthesized by a reaction between silver nitrate, 8-hydroxyquinoline-5-sulfonic acid (HQS), and 4,4'-trimethylene dipyridine (TMDP). The compound stabilizes in a noncentrosymmetric space group, and the lattice water molecules and the charge-compensating [NH4 ](+) group occupy the inter-lamellar spaces. The lattice water molecules can be fully removed and reinserted, which is accompanied by a crystalline-amorphous-crystalline transformation. This transformation resembles the collapse/delamination and restacking of the layers. To the best of our knowledge, this is the first observation of delamination and restacking in an inorganic coordination polymer that contains silver. The presence of a natural dipole (the anionic framework and cationic ammonium ions) along with the noncentrosymmetric space group gives rise to the room-temperature ferroelectric behavior of the compound. The ferroelectric behavior is also water-dependent and exhibits a ferroelectric-paraelectric transformation. The temperature-dependent dielectric measurements indicate that the ferroelectric/ paraelectric transformation occurs at 320 K. This transformation has also been investigated by using in-situ IR spectroscopy and PXRD studies. The second-harmonic generation (SHG) study indicated values that are comparable to some of the known SHG solids, such as potassium dihydrogen phosphate (KDP) and urea. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Physical Separation in the Workplace

    DEFF Research Database (Denmark)

    Stea, Diego; Foss, Nicolai Juul; Holdt Christensen, Peter


    Physical separation is pervasive in organizations, and has powerful effects on employee motivation and organizational behaviors. However, research shows that workplace separation is characterized by a variety of tradeoffs, tensions, and challenges that lead to both positive and negative outcomes....

  2. Selectivity in capillary electrokinetic separations

    NARCIS (Netherlands)

    de Zeeuw, R.A; de Jong, G.J.; Ensing, K


    This review gives a survey of selectivity modes in capillary electrophoresis separations in pharmaceutical analysis and bioanalysis. Despite the high efficiencies of these separation techniques, good selectivity is required to allow quantitation or identification of a Chemistry and Toxicology,

  3. Separation of complex mixtures of amino acids for biorefinery applications using electrodialysis

    NARCIS (Netherlands)

    Kattan Readi, O.M.; Girones nogue, Miriam; Nijmeijer, Dorothea C.


    The potential of electrodialysis (ED) for the separation of amino acids (zwitterionic molecules that exhibit a specific charge behavior dependent on pH) has been demonstrated in the past. However, even though successful for the separation of specific amino acids, ED is not applicable for the

  4. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto


    Surface charge plays an important role in membrane-based separations of particulates, macromolecules, and dissolved ionic species. In this study, we present two experimental methods to determine the concentration of negatively charged functional groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact with the membrane functional groups via complexation and electrostatic interaction, respectively, were used as probes. The amount of associated probes was quantified using liquid scintillation counting for uranium atoms and visible light spectroscopy for the toluidine blue dye. The techniques were validated using self-assembled monolayers of alkanethiols with known amounts of charged moieties. The surface density of negatively charged functional groups of hand-cast thin-film composite polyamide membranes, as well as commercial cellulose triacetate and polyamide membranes, was quantified under various conditions. Using both techniques, we measured a negatively charged functional group density of 20-30nm -2 for the hand-cast thin-film composite membranes. The ionization behavior of the membrane functional groups, determined from measurements with toluidine blue at varying pH, was consistent with published data for thin-film composite polyamide membranes. Similarly, the measured charge densities on commercial membranes were in general agreement with previous investigations. The relative simplicity of the two methods makes them a useful tool for quantifying the surface charge concentration of a variety of surfaces, including separation membranes. © 2011 Elsevier B.V.

  5. Charge Master: Friend or Foe? (United States)

    Wan, Wenshuai; Itri, Jason


    Prices charged for imaging services can be found in the charge master, a catalog of retail list prices for medical goods and services. This article reviews the evolution of reimbursement in the United States and provides a balanced discussion of the factors that influence charge master prices. Reduced payments to hospitals have pressured hospitals to generate additional revenue by increasing charge master prices. An unfortunate consequence is that those least able to pay for health care, the uninsured, are subjected to the highest charges. Yet, differences in pricing also represent an opportunity for radiology practices, which provide imaging services that are larger in scope or superior in quality to promote product differentiation. Physicians, hospital executives, and policy makers need to work together to improve the existing reimbursement system to promote high-quality, low-cost imaging. Copyright © 2016 Mosby, Inc. All rights reserved.

  6. Static Gas-Charging Plug (United States)

    Indoe, William


    A gas-charging plug can be easily analyzed for random vibration. The design features two steeped O-rings in a radial configuration at two different diameters, with a 0.050-in. (.1.3-mm) diameter through-hole between the two O-rings. In the charging state, the top O-ring is engaged and sealing. The bottom O-ring outer diameter is not squeezed, and allows air to flow by it into the tank. The inner diameter is stretched to plug the gland diameter, and is restrained by the O-ring groove. The charging port bushing provides mechanical stop to restrain the plug during gas charge removal. It also prevents the plug from becoming a projectile when removing gas charge from the accumulator. The plug can easily be verified after installation to ensure leakage requirements are met.

  7. Determine separations process strategy decision

    Energy Technology Data Exchange (ETDEWEB)

    Slaathaug, E.J.


    This study provides a summary level comparative analysis of selected, top-level, waste treatment strategies. These strategies include No Separations, Separations (high-level/low-level separations), and Deferred Separations of the tank waste. These three strategies encompass the full range of viable processing alternatives based upon full retrieval of the tank wastes. The assumption of full retrieval of the tank wastes is a predecessor decision and will not be revisited in this study.

  8. Portable refrigerant charge meter and method for determining the actual refrigerant charge in HVAC systems (United States)

    Gao, Zhiming; Abdelaziz, Omar; LaClair, Tim L.


    A refrigerant charge meter and a method for determining the actual refrigerant charge in HVAC systems are described. The meter includes means for determining an optimum refrigerant charge from system subcooling and system component parameters. The meter also includes means for determining the ratio of the actual refrigerant charge to the optimum refrigerant charge. Finally, the meter includes means for determining the actual refrigerant charge from the optimum refrigerant charge and the ratio of the actual refrigerant charge to the optimum refrigerant charge.


    Directory of Open Access Journals (Sweden)

    Zaid A. Abdulrahman


    Full Text Available Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji-Iraq. The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13 present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the  paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as  the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCAD

  10. Sedimentation of a charged porous particle in a charged cavity. (United States)

    Chang, Ya J; Keh, Huan J


    The sedimentation of a charged porous sphere at the center of a charged spherical cavity filled with an electrolyte solution is analyzed. The thickness of the electric double layers around the particle and cavity wall is arbitrary, and their relaxation effect is considered. Through the use of a set of linearized electrokinetic equations and a perturbation method, the ionic electrochemical potential energy, electric potential, and velocity fields in the fluid are solved with the fixed space charge density of the particle and surface charge density of the cavity as the small perturbation parameters, and an explicit formula for the sedimentation velocity is obtained. Due to the electroosmotic enhancement on the fluid recirculation in the cavity caused by the sedimentation-induced electric field, the presence of the surface charges on the cavity wall increases the sedimentation velocity of the porous particle. For the sedimentation of a porous particle in a cavity with their fixed charges of the same sign, the effect of electric interaction between the particle and cavity wall in general increases the sedimentation velocity. For the case of their fixed charges with opposite signs, the sedimentation velocity is increased/reduced if the magnitude of the fixed charge density of the cavity wall is relatively large/small. The effect of the surface charges at the cavity wall on the sedimentation of the porous particle increases with an increase in the permeability for fluid flow within the particle and with a decrease in the particle-to-cavity radius ratio (i.e., an increase in the surface area of the cavity wall relative to a given size of the particle, which enhances the fluid recirculation effect).

  11. Radiation by moving charges

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)


    It is generally accepted that in order to describe the dynamics of relativistic particles in the laboratory (lab) frame it is sufficient to take into account the relativistic dependence of the particle momenta on the velocity. This solution of the dynamics problem in the lab frame makes no reference to Lorentz transformations. For this reason they are not discussed in particle tracking calculations in accelerator and plasma physics. It is generally believed that the electrodynamics problem can be treated within the same ''single inertial frame'' description without reference to Lorentz transformations. In particular, in order to evaluate radiation fields arising from charged particles in motion we need to know their velocities and positions as a function of the lab frame time t. The relativistic motion of a particle in the lab frame is described by Newton's second law ''corrected'' for the relativistic dependence of momentum on velocity. It is assumed in all standard derivations that one can perform identification of the trajectories in the source part of the usual Maxwell's equations with the trajectories vector x(t) measured (or calculated by using the corrected Newton's second law) in the lab frame. This way of coupling fields and particles is considered since more than a century as the relativistically correct procedure.We argue that this procedure needs to be changed, and we demonstrate the following, completely counterintuitive statement: the results of conventional theory of radiation by relativistically moving charges are not consistent with the principle of relativity. In order to find the trajectory of a particle in the lab frame consistent with the usual Maxwell's equations, one needs to solve the dynamic equation inmanifestly covariant form by using the coordinate-independent proper time τ to parameterize the particle world-line in space-time. We show that there is a difference between &apos

  12. Fullerenes - how 25 years of charge transfer chemistry have shaped our understanding of (interfacial) interactions. (United States)

    Zieleniewska, A; Lodermeyer, F; Roth, A; Guldi, D M


    In this review article, we highlight over 25 years of fullerene research in charge transfer chemistry. The major thrust of this work is to illustrate interfacial interactions between fullerenes and porphyrins in electron donor-acceptor conjugates as well as self-assembled associates and co-crystallites all the way to organic photovoltaics. Hereby, the analysis of the fundamental proceses, namely, energy transfer, charge shift, charge separation as well as charge recombination stand at the forefront. Our examples, illustrate on how fine-tuning the structure leads to substantial alteration of interfacial interactions.

  13. Determination of sin2 θ {w/eff} using jet charge measurements in hadronic Z decays (United States)

    Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J. P.; Lucotte, A.; Minard, M. N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Palla, F.; Pater, J. R.; Pusztaszeri, J. F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wagner, A.; Wildish, T.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J. M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Ten Have, I.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H. G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H. G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J. F.; Heusse, Ph.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A. M.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M. H.; Simion, S.; Veillet, J. J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J. F.; Roussarie, A.; Schuller, J. P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Büscher, V.; Cowan, G.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Aleppo, M.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.


    The electroweak mixing angle is determined with high precision from measurements of the mean difference between forward and backward hemisphere charges in hadronic decays of the Z. A data sample of 2.5 million hadronic Z decays recorded over the period 1990 to 1994 in the ALEPH detector at LEP is used. The mean charge separation between event hemispheres containing the original quark and antiquark is measured forbbar b andcbar c events in subsamples selected by their long lifetimes or using fast D*’s. The corresponding average charge separation for light quarks is measured in an inclusive sample from the anticorrelation between charges of opposite hemispheres and agrees with predictions of hadronisation models with a precision of 2%. It is shown that differences between light quark charge separations and the measured average can be determined using hadronisation models, with systematic uncertainties constrained by measurements of inclusive production of kaons, protons and Λ’s. The separations are used to measure the electroweak mixing angle precisely as sin2 ϑ {w/eff}=0.2322±0.0008(exp.stat.) ±0.0007(exp.syst.)±0.0008(sep.). The first two errors are due to purely experimental sources whereas the third stems from uncertainties in the quark charge separations.

  14. Photoinduced charge-transfer dynamics of sequentially aligned donor-acceptor systems in an ionic liquid. (United States)

    Muramatsu, Masayasu; Katayama, Tetsuro; Ito, Syoji; Nagasawa, Yutaka; Matsuo, Daisuke; Suzuma, Yoshinori; Peng, Lifen; Orita, Akihiro; Otera, Junzo; Miyasaka, Hiroshi


    Photoinduced charge separation processes of linear phenyleneethynylene derivatives (PEN) with different sequences of electron-withdrawing perfluorophenyl groups (A) and electron-donating phenyl groups (D) were investigated in an ionic liquid (IL), BmimTFSI, by picosecond time-resolved fluorescence (TRF) and transient absorption (TA) spectroscopies. Very rapid photoinduced charge separation within 10 ps in AADD was followed by the stabilization of the charge-transfer (CT) state by the solvation, while the excited states in ADAD and ADDA were ascribable to the locally excited (LE) state. Equilibrium between the LE and CT states was established for DAAD with time constants of forward and backward processes much faster than the solvation time. The relative population of the CT state increases with time owing to the dynamic stabilization of the CT state by the solvation. The elementary charge separation process, the increase in the CT population, and their relation to the solvation time were discussed.

  15. Mapping surface charge density with a scanning nanopipette (United States)

    Klausen, Lasse Hyldgaard; Fuhs, Thomas; Besenbacher, Flemming; Dong, Mingdong


    Characterisation of the surface charge density (SCD) is important in interface and colloid science, and especially local variations in SCD of biological samples are of keen interest. The surface charge of lipid bilayers governs the uptake of charged particles and guides cell-cell interactions. As the electrostatic potential is screened by high physiological salt concentrations, direct probing of the potential can only be performed at a sub nanometer distance; therefore it was impossible to directly measure the SCD under physiological conditions. Yet the charged surface attracts counter ions leading to an enhanced ionic concentration near the surface, creating a measurable surface conductivity. In this study we measure SCD using a scanning ion-conductance microscope (SICM) setup, where the electrolyte current through a nanopipette is monitored as the pipette is positioned in the vicinity of the sample. We investigate the current dependency of SCD and pipette potential using numerical solutions to Poisson and Nernst-Planck equations and characterise a complex system governed by a multitude of factors such as pipette size, geometry and charge. We then propose an imaging method and prove its feasibility by mapping the surface charge density of phase separated lipid bilayers.

  16. Discrete space charge affected field emission: Flat and hemisphere emitters

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Kevin L., E-mail: [Code 6854, Naval Research Laboratory, Washington, DC 20375 (United States); Shiffler, Donald A.; Tang, Wilkin [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States); Rittersdorf, Ian M. [Code 6770, Naval Research Laboratory, Washington, DC 20375 (United States); Lebowitz, Joel L. [Department of Mathematics and Department of Physics, Rutgers University, Piscataway, New Jersey 08854-8019 (United States); Harris, John R. [U.S. Navy Reserve, New Orleans, Louisiana 70143 (United States); Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Petillo, John J. [Leidos, Billerica, Massachusetts 01821 (United States); Luginsland, John W. [Physics and Electronics Directorate, AFOSR, Arlington, Virginia 22203 (United States)


    Models of space-charge affected thermal-field emission from protrusions, able to incorporate the effects of both surface roughness and elongated field emitter structures in beam optics codes, are desirable but difficult. The models proposed here treat the meso-scale diode region separate from the micro-scale regions characteristic of the emission sites. The consequences of discrete emission events are given for both one-dimensional (sheets of charge) and three dimensional (rings of charge) models: in the former, results converge to steady state conditions found by theory (e.g., Rokhlenko et al. [J. Appl. Phys. 107, 014904 (2010)]) but show oscillatory structure as they do. Surface roughness or geometric features are handled using a ring of charge model, from which the image charges are found and used to modify the apex field and emitted current. The roughness model is shown to have additional constraints related to the discrete nature of electron charge. The ability of a unit cell model to treat field emitter structures and incorporate surface roughness effects inside a beam optics code is assessed.

  17. Charging of ice-vapor interfaces: applications to thunderstorms

    Directory of Open Access Journals (Sweden)

    J. Nelson


    Full Text Available The build-up of intrinsic Bjerrum and ionic defects at ice-vapor interfaces electrically charges ice surfaces and thus gives rise to many phenomena including thermoelectricity, ferroelectric ice films, sparks from objects in blizzards, electromagnetic emissions accompanying cracking in avalanches, glaciers, and sea ice, and charge transfer during ice-ice collisions in thunderstorms. Fletcher's theory of the ice surface in equilibrium proposed that the Bjerrum defects have a higher rate of creation at the surface than in the bulk, which produces a high concentration of surface D defects that then attract a high concentration of OH- ions at the surface. Here, we add to this theory the effect of a moving interface caused by growth or sublimation. This effect can increase the amount of ionic surface charges more than 10-fold for growth rates near 1 mm s-1 and can extend the spatial separation of interior charges in qualitative agreement with many observations. In addition, ice-ice collisions should generate sufficient pressure to melt ice at the contact region and we argue that the ice particle with the initially sharper point at contact loses more mass of melt than the other particle. A simple analytic model of this process with parameters that are consistent with observations leads to predicted collisional charge exchange that semiquantitatively explains the negative charging region of thunderstorms. The model also has implications for snowflake formation, ferroelectric ice, polarization of ice in snowpacks, and chemical reactions in ice surfaces

  18. Phase behavior of charged colloids : many-body effects, charge renormalization and charge regulation

    NARCIS (Netherlands)

    Zoetekouw, Bastiaan


    The main topic of this thesis is Poisson–Boltzmann theory for suspensions of charged colloids in two of its approximations: cell-type approximations that explicitly take into account non-linear effects near the colloidal surfaces, such as charge renormalization, at the expense of neglecting any

  19. The influence of charge and the distribution of charge in the polar region of phospholipids on the activity of UDP-glucuronosyltransferase. (United States)

    Zakim, D; Eibl, H


    Studies of the mechanism of lipid-induced regulation of the microsomal enzyme UDP-glucuronosyltransferase have been extended by examining the influence of charge within the polar region on the ability of lipids to activate delipidated pure enzyme. The effects of net negative charge, of charge separation in phosphocholine, and of the distribution of charge in the polar region of lipids were studied using the GT2p isoform isolated from pig liver. Prior experiments have shown that lipids with net negative charge inhibit the enzyme (Zakim, D., Cantor, M., and Eibl, H. (1988) J. Biol. Chem. 263, 5164-5169). The current experiments show that the extent of inhibition on a molar basis increases as the net negative charge increases from -1 to -2. The inhibitory effect of negatively charged lipids is on the functional state of the enzyme and is not due to electrostatic repulsion of negatively charged substrates of the enzyme. Although the inhibitory effect of net negative charge is removed when negative charge is balanced by a positive charge due to a quaternary nitrogen, neutrality of the polar region is not a sufficient condition for activation of the enzyme. In addition to a balance of charge between Pi and the quaternary nitrogen, the distance between the negative and positive charges and the orientation of the dipole created by them are critical for activation of GT2p. The negative and positive charges must be separated by the equivalent of three -CH2- groups for optimal activation by a lipid. Shortening this distance by one -CH2- unit leads to a lipid that is ineffective in activating the enzyme. Reversal of the orientation of the dipole in which the negative charge is on the polymethylene side of the lipid-water interface and the positive charge extends into water also produces a lipid that is not effective for activating GT2p. On the other hand, lipids with phosphoserine as the polar region, which has the "normal" P-N distance but carries a net negative charge, do

  20. Charge carrier dynamics in thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Strothkaemper, Christian


    This work investigates the charge carrier dynamics in three different technological approaches within the class of thin film solar cells: radial heterojunctions, the dye solar cell, and microcrystalline CuInSe{sub 2}, focusing on charge transport and separation at the electrode, and the relaxation of photogenerated charge carriers due to recombination and energy dissipation to the phonon system. This work relies mostly on optical-pump terahertz-probe (OPTP) spectroscopy, followed by transient absorption (TA) and two-photon photoemission (2PPE). The charge separation in ZnO-electrode/In{sub 2}S{sub 3}-absorber core/shell nanorods, which represent a model system of a radial heterojunction, is analyzed by OPTP. It is concluded, that the dynamics in the absorber are determined by multiple trapping, which leads to a dispersive charge transport to the electrode that lasts over hundreds of picoseconds. The high trap density on the order of 10{sup 19}/cm{sup 3} is detrimental for the injection yield, which exhibits a decrease with increasing shell thickness. The heterogeneous electron transfer from a series of model dyes into ZnO proceeds on a time-scale of 200 fs. However, the photoconductivity builds up just on a 2-10 ps timescale, and 2PPE reveals that injected electrons are meanwhile localized spatially and energetically at the interface. It is concluded that the injection proceeds through adsorbate induced interface states. This is an important result because the back reaction from long lived interface states can be expected to be much faster than from bulk states. While the charge transport in stoichiometric CuInSe{sub 2} thin films is indicative of free charge carriers, CuInSe{sub 2} with a solar cell grade composition (Cu-poor) exhibits signs of carrier localization. This detrimental effect is attributed to a high density of charged defects and a high degree of compensation, which together create a spatially fluctuating potential that inhibits charge transport. On

  1. Charge-pump voltage converter (United States)

    Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM


    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  2. Big break for charge symmetry

    CERN Document Server

    Miller, G A


    Two new experiments have detected charge-symmetry breaking, the mechanism responsible for protons and neutrons having different masses. Symmetry is a crucial concept in the theories that describe the subatomic world because it has an intimate connection with the laws of conservation. The theory of the strong interaction between quarks - quantum chromodynamics - is approximately invariant under what is called charge symmetry. In other words, if we swap an up quark for a down quark, then the strong interaction will look almost the same. This symmetry is related to the concept of sup i sospin sup , and is not the same as charge conjugation (in which a particle is replaced by its antiparticle). Charge symmetry is broken by the competition between two different effects. The first is the small difference in mass between up and down quarks, which is about 200 times less than the mass of the proton. The second is their different electric charges. The up quark has a charge of +2/3 in units of the proton charge, while ...

  3. Kinetic isoforms of intramembrane charge in intact amphibian striated muscle. (United States)

    Huang, C L


    The effects of the ryanodine receptor (RyR) antagonists ryanodine and daunorubicin on the kinetic and steady-state properties of intramembrane charge were investigated in intact voltage-clamped frog skeletal muscle fibers under conditions that minimized time-dependent ionic currents. A hypothesis that RyR gating is allosterically coupled to configurational changes in dihydropyridine receptors (DHPRs) would predict that such interactions are reciprocal and that RyR modification should influence intramembrane charge. Both agents indeed modified the time course of charging transients at 100-200-microM concentrations. They independently abolished the delayed charging phases shown by q gamma currents, even in fibers held at fully polarized, -90-mV holding potentials; such waveforms are especially prominent in extracellular solutions containing gluconate. Charge movements consistently became exponential decays to stable baselines in the absence of intervening inward or other time-dependent currents. The steady-state charge transfers nevertheless remained equal through the ON and the OFF parts of test voltage steps. The charge-voltage function, Q(VT), shifted by approximately +10 mV, particularly through those test potentials at which delayed q gamma currents normally took place but retained steepness factors (k approximately 8.0 to 10.6 mV) that indicated persistent, steeply voltage-dependent q gamma contributions. Furthermore, both RyR antagonists preserved the total charge, and its variation with holding potential, Qmax (VH), which also retained similarly high voltage sensitivities (k approximately 7.0 to 9.0 mV). RyR antagonists also preserved the separate identities of q gamma and q beta species, whether defined by their steady-state voltage dependence or inactivation or pharmacological properties. Thus, tetracaine (2 mM) reduced the available steady-state charge movement and gave shallow Q(VT) (k approximately 14 to 16 mV) and Qmax (VH) (k approximately 14 to 17 m

  4. Phase Separation Dynamics in Isotropic Ion-Intercalation Particles

    CERN Document Server

    Zeng, Yi


    Lithium-ion batteries exhibit complex nonlinear dynamics, resulting from diffusion and phase transformations coupled to ion intercalation reactions. Using the recently developed Cahn-Hilliard reaction (CHR) theory, we investigate a simple mathematical model of ion intercalation in a spherical solid nanoparticle, which predicts transitions from solid-solution radial diffusion to two-phase shrinking-core dynamics. This general approach extends previous Li-ion battery models, which either neglect phase separation or postulate a spherical shrinking-core phase boundary, by predicting phase separation only under appropriate circumstances. The effect of the applied current is captured by generalized Butler-Volmer kinetics, formulated in terms of diffusional chemical potentials, and the model consistently links the evolving concentration profile to the battery voltage. We examine sources of charge/discharge asymmetry, such as asymmetric charge transfer and surface "wetting" by ions within the solid, which can lead to...

  5. Rewritable artificial magnetic charge ice (United States)

    Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; Xu, Jing; Ocola, Leonidas E.; Divan, Ralu; Pearson, John E.; Crabtree, George W.; Kwok, Wai-Kwong


    Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. We designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the properties of other two-dimensional materials.

  6. Porous carbon nanotubes: Molecular absorption, transport, and separation (United States)

    Yzeiri, Irena; Patra, Niladri; Král, Petr


    We use classical molecular dynamics simulations to study nanofluidic properties of porous carbon nanotubes. We show that saturated water vapor condenses on the porous nanotubes, can be absorbed by them and transported in their interior. When these nanotubes are charged and placed in ionic solutions, they can selectively absorb ions in their interior and transport them. Porous carbon nanotubes can also be used as selective molecular sieves, as illustrated on a room temperature separation of benzene and ethanol.

  7. A recoil mass separator for nuclear astrophysics experiments

    CERN Document Server

    Ishiyama, H; Yoshikawa, N; Jeong, S C; Wada, M; Ishida, Y; Tanaka, M H; Takaku, S; Fuchi, Y; Kawashima, H; Katayama, I; Nomura, T; Teranishi, T; Michimasa, M; Imai, N; Yanagisawa, Y; Kubono, S; Strasser, P; Kato, S


    A recoil mass separator was constructed for experiments of nuclear astrophysics using radioactive nuclear beams, and its performance was tested. The observed beam suppression factor around M approx 20 was 10 sup - sup 4 when the system was tuned for DELTA M=1 heavier ions than beam ions. With a charge state breeding technique, it became 10 sup - sup 8 when the system was tuned for DELTA q=+1 larger ions than beam ions.

  8. Electrochemical analysis of separators used in single-chamber, air-cathode microbial fuel cells

    KAUST Repository

    Wei, Bin


    Polarization, solution-separator, charge transfer, and diffusion resistances of clean and used separator electrode assemblies were examined in microbial fuel cells using current-voltage curves and electrochemical impedance spectroscopy (EIS). Current-voltage curves showed the total resistance was reduced at low cathode potentials. EIS results revealed that at a set cathode potential of 0.3 V diffusion resistance was predominant, and it substantially increased when adding separators. However, at a lower cathode potential of 0.1 V all resistances showed only slight differences with and without separators. Used separator electrode assemblies with biofilms had increased charge transfer and diffusion resistances (0.1 V) when one separator was used; however, charge transfer resistance increased, and diffusion resistance did not appreciably change with four separators. Adding a plastic mesh to compress the separators improved maximum power densities. These results show the importance of pressing separators against the cathode, and the adverse impacts of biofilm formation on electrochemical performance. © 2012 Elsevier Ltd. All Rights Reserved.

  9. Charging of Basic Structural Shapes in a Simulated Lunar Environment (United States)

    Craven, P.; Schneider, T.; Vaughn, J.; Wang, J.; Polansky, J.


    In order to understand the effect of the charging environment on and around structures on the lunar surface, we have exposed basic structural shapes to electrons and Vacuum Ultra-Violet (VUV) radiation. The objects were, in separate runs, isolated, grounded, and placed on dielectric surfaces. In this presentation, the effects of electron energy, VUV flux, and sample orientation, on the charging of the objects will be examined. The potential of each of the object surfaces was monitored in order to determine the magnitude of the ram and wake effects under different orientations relative to the incoming beams (solar wind). This is a part of, and complementary to, the study of the group at USC under Dr. J. Wang, the purpose of which is to model the effects of the charging environment on structures on the lunar surface.

  10. Discriminant analysis and secondary-beam charge recognition (United States)

    Łukasik, J.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Bianchin, S.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; Ducret, J.-É.; Emling, H.; Frankland, J.; Hellström, M.; Henzlova, D.; Immè, G.; Iori, I.; Johansson, H.; Kezzar, K.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lühning, J.; Lynch, W. G.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; De Napoli, M.; Orth, H.; Otte, A. N.; Palit, R.; Pawłowski, P.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Sfienti, C.; Simon, H.; Sümmerer, K.; Trautmann, W.; Tsang, M. B.; Verde, G.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwiegliński, B.


    The discriminant-analysis method has been applied to optimize the exotic-beam charge recognition in a projectile fragmentation experiment. The experiment was carried out at the GSI using the fragment separator (FRS) to produce and select the relativistic secondary beams, and the ALADIN setup to measure their fragmentation products following collisions with Sn target nuclei. The beams of neutron poor isotopes around 124La and 107Sn were selected to study the isospin dependence of the limiting temperature of heavy nuclei by comparing with results for stable 124Sn projectiles. A dedicated detector to measure the projectile charge upstream of the reaction target was not used, and alternative methods had to be developed. The presented method, based on the multivariate discriminant analysis, allowed to increase the efficacy of charge recognition up to about 90%, which was about 20% more than achieved with the simple scalar methods.

  11. VT Data - Electric Charging Stations (United States)

    Vermont Center for Geographic Information — Locations of Electric Charging Stations provided by the NREL national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy....

  12. Measurements of W Charge Asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Holzbauer, J. L. [Mississippi U.


    We discuss W boson and lepton charge asymmetry measurements from W decays in the electron channel, which were made using 9.7 fb$^{-1}$ of RunII data collected by the D0 detector at the Fermilab Tevatron Collider. The electron charge asymmetry is presented as a function of pseudo-rapidity out to |$\\eta$| $\\le$ 3.2, in five symmetric and asymmetric kinematic bins of electron transverse momentum and the missing transverse energy of the event. We also give the W charge asymmetry as a function of W boson rapidity. The asymmetries are compared with next-to-leading order perturbative quantum chromodynamics calculations. These charge asymmetry measurements will allow more accurate determinations of the proton parton distribution functions and are the most precise to date.

  13. Photogeneration of charges in microcrystalline chlorophyll a

    Energy Technology Data Exchange (ETDEWEB)

    Kassi, Hassan [Scientech R and D, Inc., 2200 Rue Didbec S., Bureau 203, Trois-Rivieres, Trois-Rivieres, QC, G8Z 4H1 (Canada); Barazzouk, Said, E-mail: barazzos@uqtr.c [Groupe de Recherche en Biologie Vegetale, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC, G9A 5H7 (Canada); Brullemans, Marc [Groupe de Recherche en Biologie Vegetale, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC, G9A 5H7 (Canada); Leblanc, Roger M. [Department of Chemistry, University of Miami, P.O. Box 249118, Coral Gables, FL 33124-0431 (United States); Hotchandani, Surat [Groupe de Recherche en Biologie Vegetale, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC, G9A 5H7 (Canada)


    The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, r{sub c}, from S/I. From the temperature dependence of photogeneration, the initial separation, r{sub 0}, of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r{sub 0} compared to r{sub c} leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.

  14. Space Charge Effects in Single Molecular Devices (United States)

    Dunlap, David H.; Malliaras, George G.


    Strong negative differential resistance (NDR) has been recently observed in p-conjugated oligo (phenyleneethynylene) single-molecular devices consisting of two parallel metal (Au) electrodes which are separated by a self-assembled monolayer having a thickness on the order of 2nm [1]. The sudden drop in current suggests that nonlinear feedback associated electron transport through intermediate molecular states may be responsible for the observed NDR. We propose that the transfer of charge from the cathode to the anode takes place via nearest-neighbor hopping between two weakly coupled oligomer states. In such a case, the current is highest when the energies of the two states are coincident, and is suppressed when the voltage drop between them is sufficient to take them far out of resonance. The modification of the voltages within the junction due to accumulated space charge causes the states to become pinned. We show that this collective behavior enhances the abruptness of the NDR, and under appropriate circumstances leads to a triangularly shaped hysteresis loop in the current-voltage relation. [1] M. A. Reed, J. Chen, W. Wang, D. W. Price, A. M. Rawlett, and J. M. Tour, Appl. Phys. Lett 78, 3735 (2001)

  15. Dual Fragment Impact of PBX Charges (United States)

    Haskins, Peter; Briggs, Richard; Leeming, David; White, Nathan; Cheese, Philip; DE&S MoD UK Team; Ordnance Test Solutions Ltd Team


    Fragment impact can pose a significant hazard to many systems containing explosives or propellants. Testing for this threat is most commonly carried out using a single fragment. However, it can be argued that an initial fragment strike (or strikes) could sensitise the energetic material to subsequent impacts, which may then lead to a more violent reaction than would have been predicted based upon single fragment studies. To explore this potential hazard we have developed the capability to launch 2 fragments from the same gun at a range of velocities, and achieve impacts on an acceptor charge with good control over the spatial and temporal separation of the strikes. In this paper we will describe in detail the experimental techniques we have used, both to achieve the dual fragment launch and observe the acceptor charge response. In addition, we will describe the results obtained against PBX filled explosive targets; discuss the mechanisms controlling the target response and their significance for vulnerability assessment. Results of these tests have clearly indicated the potential for detonation upon the second strike, at velocities well below those needed for shock initiation by a single fragment.

  16. Rewritable Artificial Magnetic Charge Ice


    Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; Xu, Jing; Ocola, Leonidas E.; Divan, Ralu; Pearson, John E.; Crabtree, George W.; Kwok, Wai-Kwong


    Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. We designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge state...

  17. Measurement of the atmospheric muon charge ratio with the OPERA detector

    CERN Document Server

    Agafonova, N.; Aoki, S.; Ariga, A.; Ariga, T.; Autiero, D.; Badertscher, A.; Bagulya, A.; Bertolin, A.; Besnier, M.; Bick, D.; Boyarkin, V.; Bozza, C.; Brugiere, T.; Brugnera, R.; Brunetti, G.; Buontempo, S.; Cazes, A.; Chaussard, L.; Chernyavsky, M.; Chiarella, V.; Chon-Sen, N.; Chukanov, A.; Cozzi, M.; D'Amato, G.; Dal Corso, F.; D'Ambrosio, N.; De Lellis, G.; Declais, Y.; De Serio, M.; Di Capua, F.; Di Ferdinando, D.; Di Giovanni, A.; Di Marco, N.; Dmitrievski, S.; Dracos, M.; Duchesneau, D.; Dusini, S.; Ebert, J.; Egorov, O.; Enikeev, R.; Ereditato, A.; Esposito, L.S.; Favier, J.; Felici, G.; Ferber, T.; Fini, R.; Frekers, D.; Fukuda, T.; Fukushima, C.; Galkin, V.I.; Garfagnini, A.; Giacomelli, G.; Giorgini, M.; Goellnitz, C.; Goldberg, J.; Golubkov, D.; Goncharova, L.; Gornushkin, Y.; Grella, G.; Grianti, F.; Guler, M.; Gustavino, C.; Hagner, C.; Hamada, K.; Hara, T.; Hierholzer, M.; Hoshino, K.; Ieva, M.; Jakovcic, K.; Jollet, C.; Juget, F.; Kazuyama, M.; Kim, S.H.; Kimura, M.; Klicek, B.; Knuesel, J.; Kodama, K.; Komatsu, M.; Kose, U.; Kreslo, I.; Kubota, H.; Lazzaro, C.; Lenkeit, J.; Ljubicic, A.; Longhin, A.; Lutter, G.; Malgin, A.; Mandrioli, G.; Marotta, A.; Marteau, J.; Matsuo, T.; Matveev, V.; Mauri, N.; Medinaceli, E.; Meisel, F.; Meregaglia, A.; Migliozzi, P.; Mikado, S.; Miyamoto, S.; Monacelli, P.; Morishima, K.; Moser, U.; Muciaccia, M.T.; Naganawa, N.; Naka, T.; Nakamura, M.; Nakano, T.; Naumov, D.; Nikitina, V.; Niwa, K.; Nonoyama, Y.; Ogawa, S.; Olchevski, A.; Oldorf, C.; Orlova, G.; Osedlo, V.; Paniccia, M.; Paoloni, A.; Park, B.D.; Park, I.G.; Pastore, A.; Patrizii, L.; Pennacchio, E.; Pessard, H.; Pilipenko, V.; Pistillo, C.; Policastro, G.; Polukhina, N.; Pozzato, M.; Pretzl, K.; Publichenko, P.; Pupilli, F.; Rescigno, R.; Roganova, T.; Rokujo, H.; Romano, G.; Rosa, G.; Rostovtseva, I.; Rubbia, A.; Russo, A.; Ryasny, V.; Ryazhskaya, O.; Sato, O.; Sato, Y.; Schembri, A.; Schmidt Parzefall, W.; Schroeder, H.; Scotto Lavina, L.; Sheshukov, A.; Shibuya, H.; Simone, S.; Sioli, M.; Sirignano, C.; Sirri, G.; Song, J.S.; Spinetti, M.; Stanco, L.; Starkov, N.; Stipcevic, M.; Strauss, T.; Strolin, P.; Takahashi, S.; Tenti, M.; Terranova, F.; Tezuka, I.; Tioukov, V.; Tolun, P.; Tran, T.; Tufanli, S.; Vilain, P.; Vladimirov, M.; Votano, L.; Vuilleumier, J.L.; Wilquet, G.; Wonsak, B.; Yakushev, V.; Yoon, C.S.; Yoshioka, T.; Yoshida, J.; Zaitsev, Y.; Zemskova, S.; Zghiche, A.; Zimmermann, R.


    The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio in the TeV energy region. We analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the charge ratio dependence on the primary composition. The measured charge ratio values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the "vertical surface energy". A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum.

  18. Topological Transitions and Fractional Charges Induced by Strain and a Magnetic Field in Carbon Nanotubes (United States)

    Efroni, Yonathan; Ilani, Shahal; Berg, Erez


    We show that carbon nanotubes (CNT) can be driven through a topological phase transition using either strain or a magnetic field. This can naturally lead to Jackiw-Rebbi soliton states carrying fractionalized charges, similar to those found in a domain wall in the Su-Schrieffer-Heeger model, in a setup with a spatially inhomogeneous strain and an axial field. Two types of fractionalized states can be formed at the interface between regions with different strain: a spin-charge separated state with integer charge and spin zero (or zero charge and spin ±ℏ/2 ), and a state with charge ±e /2 and spin ±ℏ/4 . The latter state requires spin-orbit coupling in the CNT. We show that in our setup, the precise quantization of the fractionalized interface charges is a consequence of the symmetry of the CNT under a combination of a spatial rotation by π and time reversal.

  19. Effect of surface charge distribution on the crystal growth of sodium perborate tetrahydrate (United States)

    Sahın, Ömer; Nusret Bulutcu, A.


    Growth and dissolution rates of sodium perborate crystals have been measured in a flow-type single-crystal cell. Sodium perborate grows dendritically at any level of supersaturation and shows growth and dissolution rate dispersion. Both the growth and dissolution rates of sodium perborate were found to be controlled by surface charge distribution which is represented by applied voltages in an electrostatic separator. It was determined that high surface charge dominates the crystal growth rate when compared with low surface charge under identical conditions. The results obtained showed that the formation of dendritic structure is not a function of supersaturation but a function of surface charge. The rate of dissolution of a crystal with a high surface charge is greater than that with a low surface charge.

  20. Fractional Effective Charges and Misner-Wheeler Charge without Charge Effect in Metamaterials

    Directory of Open Access Journals (Sweden)

    Igor Smolyaninov


    Full Text Available Transformation optics enables engineering of the effective topology and dimensionality of the optical space in metamaterials. Nonlinear optics of such metamaterials may mimic Kaluza-Klein theories having one or more kinds of effective charges. As a result, novel photon blockade devices may be realized. Here we demonstrate that an electromagnetic wormhole may be designed, which connects two points of such an optical space and changes its effective topological connectivity. Electromagnetic field configurations, which exhibit fractional effective charges, appear as a result of such topology change. Moreover, such effects as Misner-Wheeler “charge without charge” may be replicated.

  1. Separators - Technology review: Ceramic based separators for secondary batteries (United States)

    Nestler, Tina; Schmid, Robert; Münchgesang, Wolfram; Bazhenov, Vasilii; Schilm, Jochen; Leisegang, Tilmann; Meyer, Dirk C.


    Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ("Energiewende") was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membrane - the separator - as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic-based separators

  2. Separable programming theory and methods

    CERN Document Server

    Stefanov, Stefan M


    In this book, the author considers separable programming and, in particular, one of its important cases - convex separable programming Some general results are presented, techniques of approximating the separable problem by linear programming and dynamic programming are considered Convex separable programs subject to inequality equality constraint(s) and bounds on variables are also studied and iterative algorithms of polynomial complexity are proposed As an application, these algorithms are used in the implementation of stochastic quasigradient methods to some separable stochastic programs Numerical approximation with respect to I1 and I4 norms, as a convex separable nonsmooth unconstrained minimization problem, is considered as well Audience Advanced undergraduate and graduate students, mathematical programming operations research specialists

  3. Wastewater treatment with acoustic separator (United States)

    Kambayashi, Takuya; Saeki, Tomonori; Buchanan, Ian


    Acoustic separation is a filter-free wastewater treatment method based on the forces generated in ultrasonic standing waves. In this report, a batch-system separator based on acoustic separation was demonstrated using a small-scale prototype acoustic separator to remove suspended solids from oil sand process-affected water (OSPW). By applying an acoustic separator to the batch use OSPW treatment, the required settling time, which was the time that the chemical oxygen demand (COD) decreased to the environmental criterion (<200 mg/L), could be shortened from 10 to 1 min. Moreover, for a 10 min settling time, the acoustic separator could reduce the FeCl3 dose as coagulant in OSPW treatment from 500 to 160 mg/L.

  4. Separation process using microchannel technology (United States)

    Tonkovich, Anna Lee [Dublin, OH; Perry, Steven T [Galloway, OH; Arora, Ravi [Dublin, OH; Qiu, Dongming [Bothell, WA; Lamont, Michael Jay [Hilliard, OH; Burwell, Deanna [Cleveland Heights, OH; Dritz, Terence Andrew [Worthington, OH; McDaniel, Jeffrey S [Columbus, OH; Rogers, Jr; William, A [Marysville, OH; Silva, Laura J [Dublin, OH; Weidert, Daniel J [Lewis Center, OH; Simmons, Wayne W [Dublin, OH; Chadwell, G Bradley [Reynoldsburg, OH


    The disclosed invention relates to a process and apparatus for separating a first fluid from a fluid mixture comprising the first fluid. The process comprises: (A) flowing the fluid mixture into a microchannel separator in contact with a sorption medium, the fluid mixture being maintained in the microchannel separator until at least part of the first fluid is sorbed by the sorption medium, removing non-sorbed parts of the fluid mixture from the microchannel separator; and (B) desorbing first fluid from the sorption medium and removing desorbed first fluid from the microchannel separator. The process and apparatus are suitable for separating nitrogen or methane from a fluid mixture comprising nitrogen and methane. The process and apparatus may be used for rejecting nitrogen in the upgrading of sub-quality methane.

  5. Space-charge electrostatic precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Middleton, C.E.


    An improved electrostatic precipitator called a space charge precipitator was tested and studied. A space charge precipitator differs from a conventional model in that the fields necessary to move the particles from the gas to the collecting surfaces are provided by a cloud of charged innocuous drops, such as glycerine or water, rather than by a charged electrode system. The flow conditions, electrical equipment, and physical dimensions of the test precipitator are typical of industrial applications. Experiments using water fog at a velocity of 10 ft/sec and a residence time of 0.6 sec, for a system charged at 25 kV, show a removal of iron oxide particles of approximately 52 percent. Theoretical calculations, assuming 2 micron particles, predict a removal of 50 percent. The results with glycerine fog are comparable. Experiments at various flowrates for both water fog and glycerine fog show a trend of decreasing particle removal for increasing flowrate. An identical trend is predicted by the space charge theory. Electron micrographs verify that only particles smaller than two microns are present in the laboratory precipitator.

  6. Enabling fast charging - Vehicle considerations (United States)

    Meintz, Andrew; Zhang, Jiucai; Vijayagopal, Ram; Kreutzer, Cory; Ahmed, Shabbir; Bloom, Ira; Burnham, Andrew; Carlson, Richard B.; Dias, Fernando; Dufek, Eric J.; Francfort, James; Hardy, Keith; Jansen, Andrew N.; Keyser, Matthew; Markel, Anthony; Michelbacher, Christopher; Mohanpurkar, Manish; Pesaran, Ahmad; Scoffield, Don; Shirk, Matthew; Stephens, Thomas; Tanim, Tanvir


    To achieve a successful increase in the plug-in battery electric vehicle (BEV) market, it is anticipated that a significant improvement in battery performance is required to increase the range that BEVs can travel and the rate at which they can be recharged. While the range that BEVs can travel on a single recharge is improving, the recharge rate is still much slower than the refueling rate of conventional internal combustion engine vehicles. To achieve comparable recharge times, we explore the vehicle considerations of charge rates of at least 400 kW. Faster recharge is expected to significantly mitigate the perceived deficiencies for long-distance transportation, to provide alternative charging in densely populated areas where overnight charging at home may not be possible, and to reduce range anxiety for travel within a city when unplanned charging may be required. This substantial increase in charging rate is expected to create technical issues in the design of the battery system and the vehicle's electrical architecture that must be resolved. This work focuses on vehicle system design and total recharge time to meet the goals of implementing improved charge rates and the impacts of these expected increases on system voltage and vehicle components.

  7. Hereditary separability in Hausdorff continua

    Directory of Open Access Journals (Sweden)

    D. Daniel


    Full Text Available We consider those Hausdorff continua S such that each separable subspace of S is hereditarily separable. Due to results of Ostaszewski and Rudin, respectively, all monotonically normal spaces and therefore all continuous Hausdorff images of ordered compacta also have this property. Our study focuses on the structure of such spaces that also possess one of various rim properties, with emphasis given to rim-separability. In so doing we obtain analogues of results of M. Tuncali and I. Loncar, respectively.

  8. Gas separation membrane module assembly (United States)

    Wynn, Nicholas P [Palo Alto, CA; Fulton, Donald A [Fairfield, CA


    A gas-separation membrane module assembly and a gas-separation process using the assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains a tube sheet that divides the space within the housing into two gas-tight spaces. A permeate collection system within the housing gathers permeate gas from the tubes for discharge from the housing.

  9. Method and apparatus for separating material (United States)

    Oder, Robin R.; Jamison, Russell E.


    An apparatus for sorting particles composed of a mixture of particles with differing physical and chemical characteristics. The apparatus includes a comminutor, a mechanism for removing particles from the inside of the comminutor which are intermediate in size between the feed to the comminutor and the product of comminution, a mechanism for either discharging particles taken from the comminutor to a reject stream or providing them to a size classification apparatus such as screening, a mechanism for returning the oversize particles to the comminutor or for discharging them to the reject stream, an electric mechanism for separating particles with an electrical force disposed adjacent to a magnet mechanism, a mechanism for providing the particles to the magnet mechanism and the electric mechanism and for providing triboelectric and capacitive charges to the particles, and a mechanism for returning one of the products of electric and magnetic separation to the comminutor while discharging the other to the reject stream. A method for sorting particles composed of a mixture of particles with differing physical and chemical characteristics.


    Energy Technology Data Exchange (ETDEWEB)

    R.H. Yoon; G.H. Luttrell; E.S. Yan; A.D. Walters


    Numerous advanced coal cleaning processes have been developed in recent years that are capable of substantially reducing both ash- and sulfur-forming minerals from coal. However, most of the processes involve fine grinding and use water as the cleaning medium; therefore, the clean coal products must be dewatered before they can be transported and burned. Unfortunately, dewatering fine coal is costly, which makes it difficult to deploy advanced coal cleaning processes for commercial applications. As a means of avoiding problems associated with the fine coal dewatering, the National Energy Technology Laboratory (NETL) developed a dry coal cleaning process in which mineral matter is separated from coal without using water. In this process, pulverized coal is subjected to triboelectrification before being placed in an electric field for electrostatic separation. The triboelectrification is accomplished by passing a pulverized coal through an in-line mixer made of copper. Copper has a work function that lies between that of carbonaceous material (coal) and mineral matter. Thus, coal particles impinging on the copper wall lose electrons to the metal thereby acquiring positive charges, while mineral matter impinging on the wall gain electrons to acquire negative charges. The charged particles then pass through an electric field where they are separated according to their charges into two or more products depending on the configuration of the separator. The results obtained at NETL showed that it is capable of removing more than 90% of the pyritic sulfur and 70% of the ash-forming minerals from a number of eastern U.S. coals. However, the BTU recoveries were less than desirable. The laboratory-scale batch triboelectrostatic separator (TES) used by NETL relied on adhering charged particles on parallel electrode surfaces and scraping them off. Therefore, its throughput will be proportional to the electrode surface area. If this laboratory device is scaled-up as is, it would

  11. GreenChill Store Certification Protocol for Sub-Cooling Contained on Racks Separate from Refrigeration Equipment (United States)

    Document describes the protocol used to determine the total load and refrigerant charge of stores that have placed all sub-cooling on a rack separate from all other commercial refrigeration equipment.

  12. A charge-stabilizing, multimodular, ferrocene-bis(triphenylamine)-zinc-porphyrin-fullerene polyad. (United States)

    Wijesinghe, Channa A; El-Khouly, Mohamed E; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis


    A novel multimodular donor-acceptor polyad featuring zinc porphyrin, fullerene, ferrocene, and triphenylamine entities was designed, synthesized, and studied as a charge-stabilizing, photosynthetic-antenna/reaction-center mimic. The ferrocene and fullerene entities, covalently linked to the porphyrin ring, were distantly separated to accomplish the charge-separation/hole-migration events leading to the creation of a long-lived charge-separated state. The geometry and electronic structures of the newly synthesized compound was deduced by B3LYP/3-21G(*) optimization, while the energy levels for different photochemical events was established using data from the optical absorption and emission, and electrochemical studies. Excitation of the triphenylamine entities revealed singlet-singlet energy transfer to the appended zinc porphyrin. As predicted from the energy levels, photoinduced electron transfer from both the singlet and triplet excited states of the zinc porphyrin to fullerene followed by subsequent hole migration involving ferrocene was witnessed from the transient absorption studies. The charge-separated state persisted for about 8.5 μs and was governed by the distance between the final charge-transfer product, that is, a species involving a ferrocenium cation and a fullerene radical anion, with additional influence from the charge-stabilizing triphenylamine entities located on the zinc-porphyrin macrocycle. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Waveform measurement of charge- and spin-density wavepackets in a chiral Tomonaga-Luttinger liquid (United States)

    Hashisaka, M.; Hiyama, N.; Akiho, T.; Muraki, K.; Fujisawa, T.


    In contrast to a free-electron system, a Tomonaga-Luttinger (TL) liquid in a one-dimensional (1D) electron system hosts charge and spin excitations as independent entities. When an electron is injected into a TL liquid, it transforms into charge- and spin-density wavepackets that propagate at different group velocities and move away from each other. This process, known as spin-charge separation, is the hallmark of TL physics. While spin-charge separation has been probed in momentum- or frequency-domain measurements in various 1D systems, waveforms of separated excitations, which are a direct manifestation of the TL behaviour, have been long awaited to be measured. Here, we present a waveform measurement for the pseudospin-charge separation process in a chiral TL liquid comprising quantum Hall edge channels. The charge- and pseudospin-density waveforms are captured by utilizing a spin-resolved sampling scope that records the spin-up or -down component of the excitations. This experimental technique provides full information for time evolution of the 1D electron system, including not only propagation of TL eigenmodes but also their decay in a practical device.

  14. An Investigation of Low Biofouling Copper-charged Membranes (United States)

    Asapu, Sunitha

    Water is essential for the survival of life on Earth, but pollutants in water can cause dangerous diseases and fatalities. The need for purified water has been increasing with increasing world population; however, natural sources of water such as rivers, lakes and streams, are progressively falling shorter and shorter of meeting water needs. The provision of clean, drinkable water to people is a key factor for the development of novel and alternative water purification technologies, such as membrane separations. Nanofiltration (NF) is a membrane separations technology that purifies water from lower quality sources, such as brackish water, seawater and wastewater. During the filtration of such sources, materials that are rejected by the membrane may accumulate on the surface of the membrane to foul it. Such materials include organic and inorganic matter, colloids, salts and microorganisms. The former four can often be controlled via pretreatment; however, the accumulation of microorganisms is more problematic to membranes. Biofouling is the accumulation and growth of microorganisms on the surface of membranes and on feed spacers. After attachment, microorganisms excrete extracellular polymeric substances (EPS), which form a matrix around the organism's outer surface as biofilm. These biofilms are detrimental and result in irreversible membrane fouling. Copper and silver ions inactivate the bacterial cells and prevent the DNA replication in microbial cells. Previous studies using copper-charged feed spacers have shown the ability of copper to control biofouling without a significant amount of copper leaching from copper-charged polypropylene (PP) feed spacers during crossflow filtration. Also, filtration using unmodified speed facers experienced almost 70% flux decline, while filtration using copper-charged feed spacers displayed only 25% flux decline. These intriguing results led to the hypothesis that the polymer chemistry could be extrapolated to produce membranes

  15. Coordinated Charging Strategy for Electric Taxis in Temporal and Spatial Scale

    Directory of Open Access Journals (Sweden)

    Yuqing Yang


    Full Text Available Currently, electric taxis have been deployed in many cities of China. However, the charging unbalance in both temporal and spatial scale has become a rising problem, which leads to low charging efficiency or charging congestion in different stations or time periods. This paper presents a multi-objective coordinated charging strategy for electric taxis in the temporal and spatial scale. That is, the objectives are maximizing the utilization efficiency of charging facilities, minimizing the load unbalance of the regional power system and minimizing the customers’ cost. Besides, the basic configuration of a charging station and operation rules of electric taxis would be the constraints. To tackle this multi-objective optimizing problems, a fuzzy mathematical method has been utilized to transfer the multi-objective optimization to a single optimization issue, and furthermore, the Improved Particle Swarm Optimization (IPSO Algorithm has been used to solve the optimization problem. Moreover, simulation cases are carried out, Case 1 is the original charging procedure, and Cases 2 and 3 are the temporal and spatial scale optimized separately, followed with Case 4, the combined coordinated charging. The simulation shows the significant improvement in charging facilities efficiency and users’ benefits, as well as the better dispatching of electric taxis’ charging loads.

  16. Experimental Exploration of Electrostatic Charge on Particle Pair Relative Velocity in Homogeneous and Isotropic Turbulence (United States)

    Hammond, Adam; Dou, Zhongwang; Tripathi, Anjan; Liang, Zach; Meng, Hui


    Study of droplet collision and cloud formation should consider the effects of both turbulence and electrostatic charge on particle dynamics. We present the first experimental observation of radial relative velocity (RV) of charged particles in homogeneous and isotropic turbulence (HIT). Charges on particles were generated through triboelectric effect between the inner wall of the chamber and the particles. To measure charge distribution, a particle-laden head-on impinging flow mimicking our HIT chamber conditions was built and holographic particle tracking was applied to quantify particle charges by measuring their displacements in an electric field. Particles were observed to have opposite charges. Next, in our HIT chamber, we measured particle RV by a novel 4-frame particle tracking velocimetry technique with and without charges on particles, wherein charges were neutralized by coating the interior of the HIT chamber with conductive carbon paint. We compared RV under the same turbulence conditions between charged particles and neutral particles and observed that when particles were oppositely charged, their mean inward RV increased at small separation distances. This result is consistent with recent theory and simulations (Lu and Shaw, Physics of Fluids, 2015). This work was supported by the National Science Foundation through a Collaborative Research Grant CBET-0967407.

  17. Molecular separation by thermosensitive hydrogelmembranes

    NARCIS (Netherlands)

    Feil, H.; Feil, Herman; Bae, You Han; Feijen, Jan; Kim, Sung Wan


    A new method for separation of molecules of different size is presented. The method is a useful addition to conventional separation methods which depend mainly on gel permeation chromatography using size exclusion. In the new method, hydrogel membranes are used which swelling level can be thermally

  18. Self Separation Support for UAS

    NARCIS (Netherlands)

    Tadema, J.; Theinissen, E.; Kirk, K.M.


    Recent guidance from the U.S. Federal Aviation Administration suggests that self separation needs to be a component of an Unmanned Aircraft System Sense and Avoid solution. The greater time horizon associated with self separation allows for pilot-in-the-loop operation, and, in fact, the nature of

  19. Parental separation and pediatric cancer

    DEFF Research Database (Denmark)

    Grant, Sally; Carlsen, Kathrine; Bidstrup, Pernille Envold Hansen


    The purpose of this study was to determine the risk for separation (ending cohabitation) of the parents of a child with a diagnosis of cancer.......The purpose of this study was to determine the risk for separation (ending cohabitation) of the parents of a child with a diagnosis of cancer....

  20. Family Separations in the Army (United States)


    assessment of readapting after last extended separation ......... ............. 68 14. Extent to which soldler/spouse needed time to readjust after separation...soldiers’ return ..... ....... ................... .... 71 16. Final model: Factors affecting time to readapt for spouses...anticipate that their own roles will have changed (Hunter, 1982). During the soldier’s absence, however, spouses have shouldered the responsibility of

  1. Vision 2020: 2000 Separations Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Stephen [Center for Waster Reduction Technologies; Beaver, Earl [Practical Sustainability; Bryan, Paul [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Robinson, Sharon [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Watson, Jack [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    This report documents the results of four workshops on the technology barriers, research needs, and priorities of the chemical, agricultural, petroleum, and pharmaceutical industries as they relate to separation technologies utilizing adsorbents, crystallization, distillation, extraction, membranes, separative reactors, ion exchange, bioseparations, and dilute solutions.

  2. Separable metrics and radiating stars

    Indian Academy of Sciences (India)


    Dec 14, 2016 ... and expanding spherically symmetric radiating star. We transform the junction condition to an ordinary differ- ential equation by making a separability assumption on the metric functions in the space–time variables. The condition of separability on the metric functions yields several new exact solutions.

  3. Fast Monaural Separation of Speech

    DEFF Research Database (Denmark)

    Pontoppidan, Niels Henrik; Dyrholm, Mads


    a Factorial Hidden Markov Model, with non-stationary assumptions on the source autocorrelations modelled through the Factorial Hidden Markov Model, leads to separation in the monaural case. By extending Hansens work we find that Roweis' assumptions are necessary for monaural speech separation. Furthermore we...

  4. Magnetic separation in microfluidic systems

    DEFF Research Database (Denmark)

    Smistrup, Kristian


    , and it is argued that it is a good measure, when comparing the performance of magnetic bead separators. It is described how numeric modelling is used to aid the design of microfluidic magnetic separation systems. An example of a design optimization study is given. A robust fabrication scheme has been developed...... for fabrication of silicon based systems. This fabrication scheme is explained, and it is shown how, it is applied with variations for several designs of magnetic separators. An experimental setup for magnetic separation experiments has been developed. It has been coupled with an image analysis program......This Ph.D. thesis presents theory, modeling, design, fabrication, experiments and results for microfluidic magnetic separators. A model for magnetic bead movement in a microfluidic channel is presented, and the limits of the model are discussed. The effective magnetic field gradient is defined...

  5. Separating Underdetermined Convolutive Speech Mixtures

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Wang, DeLiang; Larsen, Jan


    A limitation in many source separation tasks is that the number of source signals has to be known in advance. Further, in order to achieve good performance, the number of sources cannot exceed the number of sensors. In many real-world applications these limitations are too restrictive. We propose...... a method for underdetermined blind source separation of convolutive mixtures. The proposed framework is applicable for separation of instantaneous as well as convolutive speech mixtures. It is possible to iteratively extract each speech signal from the mixture by combining blind source separation...... techniques with binary time-frequency masking. In the proposed method, the number of source signals is not assumed to be known in advance and the number of sources is not limited to the number of microphones. Our approach needs only two microphones and the separated sounds are maintained as stereo signals....

  6. Ballistics Analysis of Orion Crew Module Separation Bolt Cover (United States)

    Howard, Samuel A.; Konno, Kevin E.; Carney, Kelly S.; Pereira, J. Michael


    NASA is currently developing a new crew module to replace capabilities of the retired Space Shuttles and to provide a crewed vehicle for exploring beyond low earth orbit. The crew module is a capsule-type design, which is designed to separate from the launch vehicle during launch ascent once the launch vehicle fuel is expended. The separation is achieved using pyrotechnic separation bolts, wherein a section of the bolt is propelled clear of the joint at high velocity by an explosive charge. The resulting projectile must be contained within the fairing structure by a containment plate. This paper describes an analytical effort completed to augment testing of various containment plate materials and thicknesses. The results help guide the design and have potential benefit for future similar applications.

  7. Separating conjoined twins: a medical and criminal law dilemma. (United States)

    Davis, Colleen


    Surgical separation of conjoined twins that results in the death of one of the twins raises complex moral, ethical and legal issues. Of particular concern is the potential for homicide charges against doctors. In two recent cases, one in England and one in Queensland, judges declared the surgery to be lawful but the legal reasoning employed is problematical and may be difficult to apply to future conjoined twins cases, such as infant twins where one is not fully developed, or where it is proposed to separate adult twins. A determination of the threshold issue of whether there are two individual persons capable of being killed may require a reconsideration of existing legal definitions and statutory provisions. Similarly, the excuses and justifications for homicide may need to be clarified or reviewed in the context of separation of conjoined twins.

  8. Cherenkov and scintillation light separation in organic liquid scintillators (United States)

    Caravaca, J.; Descamps, F. B.; Land, B. J.; Yeh, M.; Orebi Gann, G. D.


    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3 % and 63± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36± 5% and 38± 4%. LAB/PPO data is consistent with a rise time of τ _r=0.72± 0.33 ns.

  9. Light harvesting in photosystem II

    NARCIS (Netherlands)

    van Amerongen, H.; Croce, R.


    Water oxidation in photosynthesis takes place in photosystem II (PSII). This photosystem is built around a reaction center (RC) where sunlight-induced charge separation occurs. This RC consists of various polypeptides that bind only a few chromophores or pigments, next to several other cofactors. It

  10. Light-harvesting and structural organization of Photosystem II: From individual complexes to thylakoid membrane

    NARCIS (Netherlands)

    Croce, R.; van Amerongen, H.


    Photosystem II (PSII) is responsible for the water oxidation in photosynthesis and it consists of many proteins and pigment-protein complexes in a variable composition, depending on environmental conditions. Sunlight-induced charge separation lies at the basis of the photochemical reactions and it

  11. Light-harvesting and structuralorganization ofphotosystem II: from individual complexes to thylakoid membrane

    NARCIS (Netherlands)

    Croce, R.; Amerongen, van H.


    Photosystem II (PSII) is responsible for the water oxidation in photosynthesis and it consists of many proteins and pigment-protein complexes in a variable composition, depending on environmental conditions. Sunlight-induced charge separation lies at the basis of the photochemical reactions and it

  12. Photosystem II and photoinhibition

    NARCIS (Netherlands)

    Feikema, Willem Onno


    Plants harvest light energy and convert it into chemical energy. Light absorption by photosystems I and II (PSI and PSII) results in charge separations in their reaction centers (RCs), initiating a chain of redox reactions with PSI generating the reducing power for CO2 assimilation into sugars, and

  13. Alternator control for battery charging (United States)

    Brunstetter, Craig A.; Jaye, John R.; Tallarek, Glen E.; Adams, Joseph B.


    In accordance with an aspect of the present disclosure, an electrical system for an automotive vehicle has an electrical generating machine and a battery. A set point voltage, which sets an output voltage of the electrical generating machine, is set by an electronic control unit (ECU). The ECU selects one of a plurality of control modes for controlling the alternator based on an operating state of the vehicle as determined from vehicle operating parameters. The ECU selects a range for the set point voltage based on the selected control mode and then sets the set point voltage within the range based on feedback parameters for that control mode. In an aspect, the control modes include a trickle charge mode and battery charge current is the feedback parameter and the ECU controls the set point voltage within the range to maintain a predetermined battery charge current.

  14. Rewritable artificial magnetic charge ice. (United States)

    Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; Xu, Jing; Ocola, Leonidas E; Divan, Ralu; Pearson, John E; Crabtree, George W; Kwok, Wai-Kwong


    Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. We designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the properties of other two-dimensional materials. Copyright © 2016, American Association for the Advancement of Science.

  15. CHARGEd with neural crest defects. (United States)

    Pauli, Silke; Bajpai, Ruchi; Borchers, Annette


    Neural crest cells are highly migratory pluripotent cells that give rise to diverse derivatives including cartilage, bone, smooth muscle, pigment, and endocrine cells as well as neurons and glia. Abnormalities in neural crest-derived tissues contribute to the etiology of CHARGE syndrome, a complex malformation disorder that encompasses clinical symptoms like coloboma, heart defects, atresia of the choanae, retarded growth and development, genital hypoplasia, ear anomalies, and deafness. Mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene are causative of CHARGE syndrome and loss-of-function data in different model systems have firmly established a role of CHD7 in neural crest development. Here, we will summarize our current understanding of the function of CHD7 in neural crest development and discuss possible links of CHARGE syndrome to other developmental disorders. © 2017 Wiley Periodicals, Inc.


    Directory of Open Access Journals (Sweden)

    Branimir Fuk


    Full Text Available Printed circuit boards from electronic waste are very important source of precious metals by recycling. The biggest challenge is liberation and separation of useful components; thin film which contains copper, zinc, tin, lead and precious metals like silver, gold and palladium from non useful components; polymers, ceramics and glass fibbers. The paper presents results for separation of shredded printed circuit boards from TV sets in electrostatic separator. Testing where conducted with material class 2/1 and 1/0.5 mm in laboratory on equipment for mineral processing. Results showed influence from independent variable; separation knife gradient, drum rotation speed and voltage on concentrate quality and recovery (the paper is published in Croatian.

  17. Pseudo-stationary separation materials for highly parallel separations.

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anup K.; Palmer, Christopher (University of Montana, Missoula, MT)


    Goal of this study was to develop and characterize novel polymeric materials as pseudostationary phases in electrokinetic chromatography. Fundamental studies have characterized the chromatographic selectivity of the materials as a function of chemical structure and molecular conformation. The selectivities of the polymers has been studied extensively, resulting in a large body of fundamental knowledge regarding the performance and selectivity of polymeric pseudostationary phases. Two polymers have also been used for amino acid and peptide separations, and with laser induced fluorescence detection. The polymers performed well for the separation of derivatized amino acids, and provided some significant differences in selectivity relative to a commonly used micellar pseudostationary phase. The polymers did not perform well for peptide separations. The polymers were compatible with laser induced fluorescence detection, indicating that they should also be compatible with chip-based separations.

  18. 75 FR 7411 - Schedule of Water Charges (United States)


    ... COMMISSION 18 CFR Part 410 Schedule of Water Charges AGENCY: Delaware River Basin Commission. ACTION: Notice... Regulations--Water Supply Charges to revise the schedule of water charges. DATES: The Commission will hold a... the subject line ``Schedule of Water Charges.'' FOR FURTHER INFORMATION, CONTACT: Please contact Paula...

  19. 76 FR 10233 - Schedule of Water Charges (United States)


    ... COMMISSION 18 CFR Part 420 Schedule of Water Charges AGENCY: Delaware River Basin Commission. ACTION: Final...--Water Supply Charges. Accordingly, the Commission's water charging rates for consumptive use and non.... FOR FURTHER INFORMATION CONTACT: For questions about the water charging program, please contact Ms...

  20. Zp-graded charge coherent states (United States)

    Chung, Won Sang


    A new kind of charge coherent state called a Zp-graded charge coherent state is constructed by using the complex solution of the equation qp = 1. The p-1 charge operators are also explicitly constructed. We explicitly investigate some nonclassical properties for the Z3-graded charge coherent state.