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Sample records for electron acceptor conditions

  1. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Heyang; Miller, Jennifer H. [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Abu-Reesh, Ibrahim M. [Department of Chemical Engineering, Qatar University, P.O. Box 2713, Doha (Qatar); Pruden, Amy [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); He, Zhen, E-mail: zhenhe@vt.edu [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

    2016-11-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~ 2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1–2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R{sup 2} = 0.73) and ARGs vs. E. coli (R{sup 2} ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. - Highlights: • The fate of an antibiotic resistant E. coli stain and its ARGs in BES is studied. • The removal of the E. coli and its ARGs is enhanced with decreased current. • The ARGs are removed when the host E. coli dies and persist when the host survives. • The survival of the E. coli depends

  2. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions

    International Nuclear Information System (INIS)

    Yuan, Heyang; Miller, Jennifer H.; Abu-Reesh, Ibrahim M.; Pruden, Amy; He, Zhen

    2016-01-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~ 2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1–2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R 2 = 0.73) and ARGs vs. E. coli (R 2 ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. - Highlights: • The fate of an antibiotic resistant E. coli stain and its ARGs in BES is studied. • The removal of the E. coli and its ARGs is enhanced with decreased current. • The ARGs are removed when the host E. coli dies and persist when the host survives. • The survival of the E. coli depends on the

  3. Effects of electron acceptors on removal of antibiotic resistant Escherichia coli, resistance genes and class 1 integrons under anaerobic conditions.

    Science.gov (United States)

    Yuan, Heyang; Miller, Jennifer H; Abu-Reesh, Ibrahim M; Pruden, Amy; He, Zhen

    2016-11-01

    Anaerobic biotechnologies can effectively remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), but there is a need to better understand the mechanisms. Here we employ bioelectrochemical systems (BES) as a platform to investigate the fate of a native tetracycline and sulfonamide-resistant Escherichia coli strain and its ARGs. The E. coli strain carrying intI1, sulI and tet(E) was isolated from domestic wastewater and dosed into a tubular BES. The BES was first operated as a microbial fuel cell (MFC), with aeration in the cathode, which resulted in enhanced removal of E. coli and ARGs by ~2 log (i.e., order of magnitude) when switched from high current to open circuit operation mode. The BES was then operated as a microbial electrolysis cell (MEC) to exclude the effects of oxygen diffusion, and the removal of E. coli and ARGs during the open circuit configuration was again 1-2 log higher than that at high current mode. Significant correlations of E. coli vs. current (R(2)=0.73) and ARGs vs. E. coli (R(2) ranged from 0.54 to 0.87), and the fact that the BES substrate contained no electron acceptors, implied that the persistence of the E. coli and its ARGs was determined by the availability of indigenous electron acceptors in the BES, i.e., the anode electrode or the electron shuttles generated by the exoelectrogens. Subsequent experiments with pure-culture tetracycline and sulfonamide-resistant E. coli being incubated in a two-chamber MEC and serum bottles demonstrated that the E. coli could survive by respiring anode electrode and/or electron shuttles released by exoelectrogens, and ARGs persisted with their host E. coli. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Non-fullerene electron acceptors for organic photovoltaic devices

    Science.gov (United States)

    Jenekhe, Samson A.; Li, Haiyan; Earmme, Taeshik; Ren, Guoqiang

    2017-11-07

    Non-fullerene electron acceptors for highly efficient organic photovoltaic devices are described. The non-fullerene electron acceptors have an extended, rigid, .pi.-conjugated electron-deficient framework that can facilitate exciton and charge derealization. The non-fullerene electron acceptors can physically mix with a donor polymer and facilitate improved electron transport. The non-fullerene electron acceptors can be incorporated into organic electronic devices, such as photovoltaic cells.

  5. Electron Donor Acceptor Interactions. Final Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Ana L. [Arizona State Univ., Tempe, AZ (United States)

    2002-08-16

    The Gordon Research Conference (GRC) on Electron Donor Acceptor Interactions was held at Salve Regina University, Newport, Rhode Island, 8/11-16/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  6. Highly solvatochromic emission of electron donor-acceptor compounds containing propanedioato boron electron acceptors

    NARCIS (Netherlands)

    Brouwer, A.M.; Bakker, N.A.C.; Wiering, P.G.; Verhoeven, J.W.

    1991-01-01

    Light-induced electron transfer occurs in bifunctional compounds consisting of 1,3-diphenylpropanedioato boron oxalate or fluoride electron acceptors and simple aromatic electron-donor groups, linked by a methylene bridge; fluorescence from the highly polar charge-transfer excited state is

  7. Spectroscopic Studies of the Electron Donor-Acceptor Interaction of ...

    African Journals Online (AJOL)

    Purpose: The electron donor-acceptor interaction between drugs which act as electron donors and some electron-deficient compounds (π acceptors) has severally been utilized as an analytical tool for the quantitation and qualitative assessment of such drugs. The objective of this study, therefore, was to develop an assay ...

  8. Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor

    Science.gov (United States)

    Myers, Charles R.; Nealson, Kenneth H.

    1988-01-01

    Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

  9. An overview of electron acceptors in microbial fuel cells

    DEFF Research Database (Denmark)

    Ucar, Deniz; Zhang, Yifeng; Angelidaki, Irini

    2017-01-01

    Microbial fuel cells (MFC) have recently received increasing attention due to their promising potential in sustainable wastewater treatment and contaminant removal. In general, contaminants can be removed either as an electron donor via microbial catalyzed oxidization at the anode or removed...... as an electron acceptor due to its high oxidation potential and ready availability. Recent studies, however, have begun to assess the use of different electron acceptors because of the (1) diversity of redox potential, (2) needs of alternative and more efficient cathode reaction, and (3) expanding of MFC based...... technologies in different areas. The aim of this review was to evaluate the performance and applicability of various electron acceptors and mediators used in MFCs. This review also evaluated the corresponding performance, advantages and disadvantages, and future potential applications of select electron...

  10. Electrodes as Terminal Electron Acceptors in Anaerobic Ammonium Oxidation

    Science.gov (United States)

    Ruiz-Urigüen, M.; Jaffe, P. R.

    2017-12-01

    Anaerobic ammonium (NH4+) oxidation under iron (Fe) reducing conditions is a microbial- mediated process known as Feammox. This is a novel pathway in the nitrogen cycle, and a key process for alleviating NH4+ accumulation in anoxic soils, wetlands, and wastewater. Acidimicrobiaceae-bacterium A6, phylum Actinobacteria, are one type of autotrophic bacteria linked to this process. The Feammox-bacteria obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, iron oxides are the TEAs. However, in this study we show that electrodes in Microbial Electrolysis Cells (MECs) or electrodes set in the field can be used as TEAs by Feammox-bacteria. The potential difference between electrodes is the driving force for electron transfer, making the reaction energetically feasible. Our results show that MECs containing Feammox cultures can remove NH4+ up to 3.5 mg/L in less than 4 hours, compared to an average of 9 mg/L in 2 weeks when cultured under traditional conditions. Concomitantly, MECs produce an average current of 30.5 A/m3 whilst dead bacteria produced low (application of Feammox-bacteria.

  11. Acceptors in cadmium telluride. Identification and electronic structure

    International Nuclear Information System (INIS)

    Molva, E.

    1983-11-01

    It is shown that electronic properties of CdTe are determined by impurities more than by intrinsic defects like vacancies or interstitials in Cd or Te contrary to classical theories. These results are based on annealing, diffusion, implantation and electron irradiation at 4 K. Centers appearing in treated samples are accurately identified by photoluminescence, cathodoluminescence infra-red absorption, electrical measurements and magneto-optic properties. Acceptors identified are Li, Na, Cu, Ag and Au impurities in Cd and N, P and As in Te. Energy levels of all acceptors and fine structure of excitons are determined [fr

  12. Electron Acceptor Materials Engineering in Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Liu, Huan

    2011-07-15

    Lead sulfide colloidal quantum dot (CQD) solar cells with a solar power conversion efficiency of 5.6% are reported. The result is achieved through careful optimization of the titanium dioxide electrode that serves as the electron acceptor. Metal-ion-doped sol-gel-derived titanium dioxide electrodes produce a tunable-bandedge, well-passivated materials platform for CQD solar cell optimization. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems

    KAUST Repository

    Alsulami, Qana A.

    2016-11-30

    The efficiency of photoconversion systems, such as organic photovoltaic (OPV) cells, is largely controlled by a series of fundamental photophysical processes occurring at the interface before carrier collection. A profound understanding of ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) is the key determinant to improving the overall performances of photovoltaic devices. The discussion in this dissertation primarily focuses on the relevant parameters that are involved in photon absorption, exciton separation, carrier transport, carrier recombination and carrier collection in organic photovoltaic devices. A combination of steady-state and femtosecond broadband transient spectroscopies was used to investigate the photoinduced charge carrier dynamics in various donor-acceptor systems. Furthermore, this study was extended to investigate some important factors that influence charge transfer in donor-acceptor systems, such as the morphology, energy band alignment, electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance are found. In this thesis, we explored the significant impacts of ultrafast charge separation and charge recombination at donor/acceptor (D/A) interfaces on the performance of a conjugated polymer PTB7-Th device with three fullerene acceptors: PC71BM, PC61BM and IC60BA. Time-resolved laser spectroscopy and high-resolution electron microscopy can illustrate the basis for fabricating solar cell devices with improved performances. In addition, we studied the effects of the incorporation of heavy metals into π-conjugated chromophores on electron transfer by monitoring the triplet state lifetime of the oligomer using transient absorption spectroscopy, as understanding the mechanisms controlling intersystem crossing and

  14. 2012 Gordon Research Conference, Electron donor-acceptor interactions, August 5-10 2012

    Energy Technology Data Exchange (ETDEWEB)

    McCusker, James [Michigan State Univ., East Lansing, MI (United States)

    2012-08-10

    The upcoming incarnation of the Gordon Research Conference on Electron Donor Acceptor Interactions will feature sessions on classic topics including proton-coupled electron transfer, dye-sensitized solar cells, and biological electron transfer, as well as emerging areas such as quantum coherence effects in donor-acceptor interactions, spintronics, and the application of donor-acceptor interactions in chemical synthesis.

  15. Fullerene derivatives as electron acceptors for organic photovoltaic cells.

    Science.gov (United States)

    Mi, Dongbo; Kim, Ji-Hoon; Kim, Hee Un; Xu, Fei; Hwang, Do-Hoon

    2014-02-01

    Energy is currently one of the most important problems humankind faces. Depletion of traditional energy sources such as coal and oil results in the need to develop new ways to create, transport, and store electricity. In this regard, the sun, which can be considered as a giant nuclear fusion reactor, represents the most powerful source of energy available in our solar system. For photovoltaic cells to gain widespread acceptance as a source of clean and renewable energy, the cost per watt of solar energy must be decreased. Organic photovoltaic cells, developed in the past two decades, have potential as alternatives to traditional inorganic semiconductor photovoltaic cells, which suffer from high environmental pollution and energy consumption during production. Organic photovoltaic cells are composed of a blended film of a conjugated-polymer donor and a soluble fullerene-derivative acceptor sandwiched between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-coated indium tin oxide positive electrode and a low-work-function metal negative electrode. Considerable research efforts aim at designing and synthesizing novel fullerene derivatives as electron acceptors with up-raised lowest unoccupied molecular orbital energy, better light-harvesting properties, higher electron mobility, and better miscibility with the polymer donor for improving the power conversion efficiency of the organic photovoltaic cells. In this paper, we systematically review novel fullerene acceptors synthesized through chemical modification for enhancing the photovoltaic performance by increasing open-circuit voltage, short-circuit current, and fill factor, which determine the performance of organic photovoltaic cells.

  16. Influence of petroleum deposit geometry on local gradient of electron acceptors and microbial catabolic potential.

    Science.gov (United States)

    Singh, Gargi; Pruden, Amy; Widdowson, Mark A

    2012-06-05

    A field survey was conducted following the Deepwater Horizon blowout and it was noted that resulting coastal petroleum deposits possessed distinct geometries, ranging from small tar balls to expansive horizontal oil sheets. A subsequent laboratory study evaluated the effect of oil deposit geometry on localized gradients of electron acceptors and microbial community composition, factors that are critical to accurately estimating biodegradation rates. One-dimensional top-flow sand columns with 12-h simulated tidal cycles compared two contrasting geometries (isolated tar "balls" versus horizontal "sheets") relative to an oil-free control. Significant differences in the effluent dissolved oxygen and sulfate concentrations were noted among the columns, indicating presence of anaerobic zones in the oiled columns, particularly in the sheet condition. Furthermore, quantification of genetic markers of terminal electron acceptor and catabolic processes via quantitative polymerase chain reaction of dsrA (sulfate-reduction), mcrA (methanogenesis), and cat23 (oxygenation of aromatics) genes in column cores suggested more extensive anaerobic conditions induced by the sheet relative to the ball geometry. Denaturing gradient gel electrophoresis similarly revealed that distinct gradients of bacterial communities established in response to the different geometries. Thus, petroleum deposit geometry impacts local dominant electron acceptor conditions and may be a key factor for advancing attenuation models and prioritizing cleanup.

  17. Anaerobic α-Amylase Production and Secretion with Fumarate as the Final Electron Acceptor in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Liu, Zihe; Österlund, Tobias; Hou, Jin

    2013-01-01

    In this study, we focus on production of heterologous α-amylase in the yeast Saccharomyces cerevisiae under anaerobic conditions. We compare the metabolic fluxes and transcriptional regulation under aerobic and anaerobic conditions, with the objective of identifying the final electron acceptor...... reticulum are transferred to fumarate as the final electron acceptor. This model is supported by findings that the addition of fumarate under anaerobic (but not aerobic) conditions improves cell growth, specifically in the α-amylase-producing strain, in which it is not used as a carbon source. Our results...... provide a model for the molecular mechanism of anaerobic protein secretion using fumarate as the final electron acceptor, which may allow for further engineering of yeast for improved protein secretion under anaerobic growth conditions....

  18. Reduction of low potential electron acceptors requires the CbcL inner membrane cytochrome of Geobacter sulfurreducens.

    Science.gov (United States)

    Zacharoff, Lori; Chan, Chi Ho; Bond, Daniel R

    2016-02-01

    The respiration of metals by the bacterium Geobacter sulfurreducens requires electrons generated by metabolism to pass from the interior of the cell to electron acceptors beyond the cell membranes. The G. sulfurreducens inner membrane multiheme c-type cytochrome ImcH is required for respiration to extracellular electron acceptors with redox potentials greater than -0.1 V vs. SHE, but ImcH is not essential for electron transfer to lower potential acceptors. In contrast, deletion of cbcL, encoding an inner membrane protein consisting of b-type and multiheme c-type cytochrome domains, severely affected reduction of low potential electron acceptors such as Fe(III)-oxides and electrodes poised at -0.1 V vs. SHE. Catalytic cyclic voltammetry of a ΔcbcL strain growing on poised electrodes revealed a 50 mV positive shift in driving force required for electron transfer out of the cell. In non-catalytic conditions, low-potential peaks present in wild type biofilms were absent in ∆cbcL mutants. Expression of cbcL in trans increased growth at low redox potential and restored features to cyclic voltammetry. This evidence supports a model where CbcL is a component of a second electron transfer pathway out of the G. sulfurreducens inner membrane that dominates when redox potential is at or below -0.1 V vs. SHE. Copyright © 2015. Published by Elsevier B.V.

  19. Effect of potential electron acceptors on anoxic ammonia oxidation in the presence of organic carbon

    Energy Technology Data Exchange (ETDEWEB)

    Sabumon, P.C., E-mail: pcsabumon@yahoo.co.in [Environmental Engineering Division, School of Mechanical and Building Sciences, VIT University, Vellore 632 014 (India)

    2009-12-15

    A novel route of anoxic ammonia removal in the presence of organic carbon was identified recently from ecosystems contaminated with ammonia. Sequencing batch reactor (SBR) studies were carried out in anoxic condition at oxidation-reduction potential varied from -185 to -275 mV for anoxic ammonia oxidation with adapted biomass (mixed culture). SBR studies were carried out in absence and in the presence of externally added organic carbon and/or in the presence of inorganic electron acceptors like NO{sub 2}{sup -}, NO{sub 3}{sup -} and SO{sub 4}{sup 2-}. The results showed anoxic ammonia oxidation to nitrate (in contrast to reported anammox process) in the presence of organic carbon available through endogenous respiration whereas anoxic ammonia oxidation was effective in the presence of externally added organic compound for nitrogen removal. The presence of externally added inorganic electron acceptors like NO{sub 2}{sup -}, NO{sub 3}{sup -} and SO{sub 4}{sup 2-} was effective in anoxic ammonia oxidation, but failed to follow the reported anammox reaction's stoichiometry in nitrogen removal in the presence of organic carbon. However, the presence of NO{sub 2}{sup -} affected best in total nitrogen removal compared to other electron acceptors and maximum ammonia removal rate was 100 mg NH{sub 4}{sup +}/g MLVSS/d. Based on the results, it is possible to suggest that rate of anoxic ammonia oxidation depends up on the respiration activities of mixed culture involving organic carbon, NO{sub 2}{sup -}, NO{sub 3}{sup -} and SO{sub 4}{sup 2-}. The process shows possibilities of new pathways of ammonia oxidation in organic contaminated sediments and/or wastewater in anoxic conditions.

  20. Flexible biological arsenite oxidation utilizing NOxand O2as alternative electron acceptors.

    Science.gov (United States)

    Wang, Jie; Wan, Junfeng; Wu, Zihao; Li, Hongli; Li, Haisong; Dagot, Christophe; Wang, Yan

    2017-07-01

    The feasibility of flexible microbial arsenite (As III ) oxidation coupled with the reduction of different electron acceptors was investigated. The results indicated the acclimated microorganisms could oxidize As III with oxygen, nitrate and nitrite as the alternative electron acceptors. A series of batch tests were conducted to measure the kinetic parameters of As III oxidation and to evaluate the effects of environmental conditions including pH and temperature on the activity of biological As III oxidation dependent on different electron acceptors. Kinetic results showed that oxygen-dependent As III oxidation had the highest oxidation rate (0.59 mg As g -1  VSS min -1 ), followed by nitrate- (0.40 mg As g -1  VSS min -1 ) and nitrite-dependent As III oxidation (0.32 mg As g -1  VSS min -1 ). The kinetic data of aerobic As III oxidation were fitted well with the Monod kinetic model, while the Haldane substrate inhibition model was better applicable to describe the inhibition of anoxic As III oxidation. Both aerobic and anoxic As III oxidation performed the optimal activity at the near neutral pH. Besides, the optimal temperature for oxygen-, nitrate- and nitrite-dependent As III oxidation was 30 ± 1 °C, 40 ± 1 °C and 20 ± 1 °C, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. A New Polymer Electron Acceptor Based on Thiophene-S,S-dioxide Unit for Organic Photovoltaics.

    Science.gov (United States)

    Meng, Bin; Miao, Junhui; Liu, Jun; Wang, Lixiang

    2018-01-01

    For polymer solar cells (PSCs), efficient polymer electron acceptors are always based on strong electron-withdrawing imide unit or boron-nitrogen coordinative bond (B←N). In this paper, a new polymer electron acceptor based on thiophene-S,S-dioxide (TDO) unit is reported. The polymer electron acceptor, PBDT-TDO, consists of alternating TDO unit and 4,8-bis(alkylthienyl)-2-yl]benzo[1,2-b:4,5-b']dithiophene (BDT) unit. For comparison, a control polymer with alternating BDT unit and thiophene unit has also been synthesized. Replacing thiophene unit with TDO unit in the polymer backbone leads to large downshift of lowest unoccupied molecular orbital/highest occupied molecular orbital energy levels by 0.9 eV/0.4 eV, which is attributed to the dearomatization and electron deficiency of TDO unit. The replacement also leads to redshift of absorption spectra by ≈110 nm. PSC device with PBDT-TDO as the electron acceptor shows photovoltaic response with the preliminary power conversion efficiency of 0.64%. This work suggests a new approach to design polymer electron acceptors using the TDO unit. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Conduction electrons in acceptor-doped GaAs/GaAlAs heterostructures: a review

    International Nuclear Information System (INIS)

    Zawadzki, Wlodek; Raymond, Andre; Kubisa, Maciej

    2016-01-01

    We review magneto-optical and magneto-transport effects in GaAs/GaAlAs heterostructures doped in GaAlAs barriers with donors, providing two-dimensional (2D) electron gas (2DEG) in GaAs quantum wells (QWS), and additionally doped with smaller amounts of acceptors (mostly Be atoms) in the vicinity of 2DEG. One may also deal with residual acceptors (mostly C atoms). The behavior of such systems in the presence of a magnetic field differs appreciably from those doped in the vicinity of 2DEG with donors. Three subjects related to the acceptor-doped heterostructures are considered. First is the problem of bound states of conduction electrons confined to the vicinity of negatively charged acceptors by the joint effect of a QW and an external magnetic field parallel to the growth direction. A variational theory of such states is presented, demonstrating that an electron turning around a repulsive center has discrete energies above the corresponding Landau levels. Experimental evidence for the discrete electron energies comes from the work on interband photo-magneto-luminescence, intraband cyclotron resonance and quantum magneto-transport (the Quantum Hall and Shubnikov–de Haas effects). An electron rain-down effect at weak electric fields and a boil-off effect at strong electric fields are introduced. It is demonstrated, both theoretically and experimentally, that a negatively charged acceptor can localize more than one electron. The second subject describes experiment and theory of asymmetric quantized Hall and Shubnikov–de Haas plateaus in acceptor-doped GaAs/GaAlAs heterostructures. It is shown that the main features of the plateau asymmetry can be attributed to asymmetric density of Landau states in the presence of acceptors. However, at high magnetic fields, the rain-down effect is also at work. The third subject deals with the so-called disorder modes (DMs) in the cyclotron resonance of conduction electrons. The DMs originate from random distributions of

  3. Donor–acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions

    Directory of Open Access Journals (Sweden)

    Anastasios Stergiou

    2014-09-01

    Full Text Available Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor–acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor–acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor–acceptor graphene-based hybrids, will be discussed.

  4. Non-Fullerene Electron Acceptors for Use in Organic Solar Cells

    KAUST Repository

    Nielsen, Christian B.

    2015-10-27

    The active layer in a solution processed organic photovoltaic device comprises a light absorbing electron donor semiconductor, typically a polymer, and an electron accepting fullerene acceptor. Although there has been huge effort targeted to optimize the absorbing, energetic, and transport properties of the donor material, fullerenes remain as the exclusive electron acceptor in all high performance devices. Very recently, some new non-fullerene acceptors have been demonstrated to outperform fullerenes in comparative devices. This Account describes this progress, discussing molecular design considerations and the structure–property relationships that are emerging. The motivation to replace fullerene acceptors stems from their synthetic inflexibility, leading to constraints in manipulating frontier energy levels, as well as poor absorption in the solar spectrum range, and an inherent tendency to undergo postfabrication crystallization, resulting in device instability. New acceptors have to address these limitations, providing tunable absorption with high extinction coefficients, thus contributing to device photocurrent. The ability to vary and optimize the lowest unoccupied molecular orbital (LUMO) energy level for a specific donor polymer is also an important requirement, ensuring minimal energy loss on electron transfer and as high an internal voltage as possible. Initially perylene diimide acceptors were evaluated as promising acceptor materials. These electron deficient aromatic molecules can exhibit good electron transport, facilitated by close packed herringbone crystal motifs, and their energy levels can be synthetically tuned. The principal drawback of this class of materials, their tendency to crystallize on too large a length scale for an optimal heterojunction nanostructure, has been shown to be overcome through introduction of conformation twisting through steric effects. This has been primarily achieved by coupling two units together, forming dimers

  5. Mechanism of electron transfer from e-sub(aq) to acceptors in micelles

    International Nuclear Information System (INIS)

    Graetzel, M.; Henglein, A.; Janata, E.

    1975-01-01

    Pulse radiolysis experiments were carried out to investigate reactions A + e - sub(aq) → A - of hydrated electrons with acceptors A incorporated in the lipoidic part of micellar 10 -3 M sodium-lauryl-sulfate (SLS) and cetyl-trimethyl-ammonium-bromide (CTAB). The acceptors were 9-nitro-anthracene and pyrene, the latter in both the singlet and triplet state (the triplet was produced by UV-light irradiation shortly before the high energy electron pulse was applied). The triplet state of pyrene reacts in CTAB-micelles with a rate constant smaller by at least a factor of two than the singlet ground state. (orig./HK) [de

  6. An Electron Acceptor with Porphyrin and Perylene Bisimides for Efficient Non-Fullerene Solar Cells.

    Science.gov (United States)

    Zhang, Andong; Li, Cheng; Yang, Fan; Zhang, Jianqi; Wang, Zhaohui; Wei, Zhixiang; Li, Weiwei

    2017-03-01

    A star-shaped electron acceptor based on porphyrin as a core and perylene bisimide as end groups was constructed for application in non-fullerene organic solar cells. The new conjugated molecule exhibits aligned energy levels, good electron mobility, and complementary absorption with a donor polymer. These advantages facilitate a high power conversion efficiency of 7.4 % in non-fullerene solar cells, which represents the highest photovoltaic performance based on porphyrin derivatives as the acceptor. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Reactive Black 5 as electron donor and/or electron acceptor in dual chamber of solar photocatalytic fuel cell.

    Science.gov (United States)

    Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusuf, Sara Yasina; Yusoff, NikAthirah; Lee, Sin-Li

    2018-03-19

    The role of azo dye Reactive Black 5 (RB5) as an electron donor and/or electron acceptor could be distinguished in dual chamber of photocatalytic fuel cell (PFC). The introduction of RB5 in anode chamber increased the voltage generation in the system since degradation of RB5 might produce electrons which also would transfer through external circuit to the cathode chamber. The removal efficiency of RB5 with open and closed circuit was 8.5% and 13.6%, respectively and removal efficiency for open circuit was low due to the fact that recombination of electron-hole pairs might happen in anode chamber since without connection to the cathode, electron cannot be transferred. The degradation of RB5 in cathode chamber with absence of oxygen showed that electrons from anode chamber was accepted by dye molecules to break its azo bond. The presence of oxygen in cathode chamber would improve the oxygen reduction rate which occurred at Platinum-loaded carbon (Pt/C) cathode electrode. The V oc , J sc and P max for different condition of ultrapure water at cathode chamber also affected their fill factor. The transportation of protons to cathode chamber through Nafion membrane could decrease the pH of ultrapure water in cathode chamber and undergo hydrogen evolution reaction in the absence of oxygen which then increased degradation rate of RB5 as well as its electricity generation. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Activated Carbon as an Electron Acceptor and Redox Mediator during the Anaerobic Biotransformation of Azo Dyes

    NARCIS (Netherlands)

    Zee, van der F.P.; Bisschops, I.A.E.; Lettinga, G.; Field, J.A.

    2003-01-01

    The role of AC as redox mediator in accelerating the reductive transformation of pollutants as well as a terminal electron acceptor in the biological oxidation of an organic substrate is described. This study explores the use of AC as an immobilized redox mediator for the reduction of a recalcitrant

  9. High performance weak donor-acceptor polymers in thin film transistors: effect of the acceptor on electronic properties, ambipolar conductivity, mobility, and thermal stability.

    Science.gov (United States)

    Yuen, Jonathan D; Fan, Jian; Seifter, Jason; Lim, Bogyu; Hufschmid, Ryan; Heeger, Alan J; Wudl, Fred

    2011-12-28

    We have studied the electronic, physical, and transistor properties of a family of donor-acceptor polymers consisting of diketopyrrolopyrrole (DPP) coupled with different accepting companion units in order to determine the effects of donor-acceptor interaction. Using the electronically neutral benzene (B), the weakly accepting benzothiadiazole (BT), and the strongly accepting benzobisthiadiazole (BBT), the accepting strength of the companion unit was systematically modulated. All polymers exhibited excellent transistor performance, with mobilities above 0.1 cm(2)V(-1)s(-1), even exceeding 1 cm(2)V(-1)s(-1) for one of the BBT-containing polymers. We find that the BBT is the strongest acceptor, enabling the BBT-containing polymers to be strongly ambipolar. The BBT moiety also strengthens interchain interactions, which provides higher thermal stability and performance for transistors with BBT-containing polymers as the active layer. © 2011 American Chemical Society

  10. Phasic availability of terminal electron acceptor on oxygen reduction reaction in microbial fuel cell.

    Science.gov (United States)

    Shanthi Sravan, J; Butti, Sai Kishore; Verma, Anil; Venkata Mohan, S

    2017-10-01

    Oxygen-reduction reactions (ORR) plays a pivotal role in determining microbial fuel cells (MFC) performance. In this study, an attempt to determine the influence of the phasic availability of terminal electron acceptor (TEA) on ORR was made. Two MFCs operated with dissolved oxygen (MFC-DC) and air (MFC-SC) as TEA were constructed and analyzed in continuous mode under open and closed circuit conditions. The bio-electrochemical analysis showed a marked influence of dissolved oxygen resulting in a maximum power density with MFC-DC (769mW/m 2 ) compared to MFC-SC (684mW/m 2 ). The availability of O 2 in dissolved phase has lowered the activation losses during the MFC operation as a result of effective ORR. The cyclic voltammetry analysis revealed the TEA dependent biocatalyst activity of NADH and cytochrome complex which enabled electron transfer kinetics and improved substrate utilization. Finally, the study evidenced the critical role of TEA phasic availability to regulate the bio-electrogenic and substrate degradation potential in MFC. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Localization of xanthine oxidoreductase activity using the tissue protectant polyvinyl alcohol and final electron acceptor Tetranitro BT

    NARCIS (Netherlands)

    Kooij, A.; Frederiks, W. M.; Gossrau, R.; van Noorden, C. J.

    1991-01-01

    We have detected xanthine oxidoreductase activity in unfixed cryostat sections of rat and chicken liver, rat duodenum, and bovine mammary gland using the tissue protectant polyvinyl alcohol, the electron carrier 1-methoxyphenazine methosulfate, the final electron acceptor Tetranitro BT, and

  12. Positron Spur Reactions with Excess Electrons and Anions in Liquid Organic Mixtures of Electron Acceptors

    DEFF Research Database (Denmark)

    Lévay, B.; Mogensen, O. E.

    1980-01-01

    cyclohexane, but did not appear in the aromatic benzene. This might be explained by the weak electron acceptor property of aromatics. In the Ps yield versus SF6 concentration curve in hexane a similar minimum appeared as in the CS2 case, probably by the same reason. By adding 0.8 M CS2 to the system...... the minimum was shifted towards the lower concentrations, which might be explained by some overlap of the energy levels on CS2 and SF6. Antiinhibition effect of C6F6 and CS2 was studied in 0.05 M CCl4/hexane solutions. In the CS2 case first a small minimum appeared in the Ps yield versus CS2 concentration...... curve. Alcohol clusters did not show antiinhibition in 0.05 M CCl4/neopentane system. Weak electron scavengers (C6F6, naphthalene, biphenyl, benzene) which generally act as antiinhibitors were added to pure non-polar solvents (hexane, isooctane, cyclohexane) and caused Ps enhancement. This can...

  13. Charge transfer in the electron donor-acceptor complex BH3NH3.

    Science.gov (United States)

    Mo, Yirong; Song, Lingchun; Wu, Wei; Zhang, Qianer

    2004-03-31

    As a simple yet strongly binding electron donor-acceptor (EDA) complex, BH(3)NH(3) serves as a good example to study the electron pair donor-acceptor complexes. We employed both the ab initio valence bond (VB) and block-localized wave function (BLW) methods to explore the electron transfer from NH(3) to BH(3). Conventionally, EDA complexes have been described by two diabatic states: one neutral state and one ionic charge-transferred state. Ab initio VB self-consistent field (VBSCF) computations generate the energy profiles of the two diabatic states together with the adiabatic (ground) state. Our calculations evidently demonstrated that the electron transfer between NH(3) and BH(3) falls in the abnormal regime where the reorganization energy is less than the exoergicity of the reaction. The nature of the NH(3)-BH(3) interaction is probed by an energy decomposition scheme based on the BLW method. We found that the variation of the charge-transfer energy with the donor-acceptor distance is insensitive to the computation levels and basis sets, but the estimation of the amount of electron transferred heavily depends on the population analysis procedures. The recent resurgence of interest in the nature of the rotation barrier in ethane prompted us to analyze the conformational change of BH(3)NH(3), which is an isoelectronic system with ethane. We found that the preference of the staggered structure over the eclipsed structure of BH(3)NH(3) is dominated by the Pauli exchange repulsion.

  14. Interplay of alternative conjugated pathways and steric interactions on the electronic and optical properties of donor-acceptor conjugated polymers

    KAUST Repository

    Lima, Igo T.

    2014-01-01

    Donor-acceptor π-conjugated copolymers are of interest for a wide range of electronic applications, including field-effect transistors and solar cells. Here, we present a density functional theory (DFT) study of the impact of varying the conjugation pathway on the geometric, electronic, and optical properties of donor-acceptor systems. We consider both linear ("in series"), traditional conjugation among the donor-acceptor moieties versus structures where the acceptor units are appended orthogonally to the linear, donor-only conjugated backbone. Long-range-corrected hybrid functionals are used in the investigation with the values of the tuned long-range separation parameters providing an estimate of the extent of conjugation as a function of the oligomer architecture. Considerable differences in the electronic and optical properties are determined as a function of the nature of the conjugation pathway, features that should be taken into account in the design of donor-acceptor copolymers.

  15. Metabolism of Fructophilic Lactic Acid Bacteria Isolated from the Apis mellifera L. Bee Gut: Phenolic Acids as External Electron Acceptors

    Science.gov (United States)

    Filannino, Pasquale; Addante, Rocco; Pontonio, Erica; Gobbetti, Marco

    2016-01-01

    ABSTRACT Fructophilic lactic acid bacteria (FLAB) are strongly associated with the gastrointestinal tracts (GITs) of Apis mellifera L. worker bees due to the consumption of fructose as a major carbohydrate. Seventy-seven presumptive lactic acid bacteria (LAB) were isolated from GITs of healthy A. mellifera L. adults, which were collected from 5 different geographical locations of the Apulia region of Italy. Almost all of the isolates showed fructophilic tendencies: these isolates were identified as Lactobacillus kunkeei (69%) or Fructobacillus fructosus (31%). A high-throughput phenotypic microarray targeting 190 carbon sources was used to determine that 83 compounds were differentially consumed. Phenotyping grouped the strains into two clusters, reflecting growth performance. The utilization of phenolic acids, such as p-coumaric, caffeic, syringic, or gallic acids, as electron acceptors was investigated in fructose-based medium. Almost all FLAB strains showed tolerance to high phenolic acid concentrations. p-Coumaric acid and caffeic acid were consumed by all FLAB strains through reductases or decarboxylases. Syringic and gallic acids were partially metabolized. The data collected suggest that FLAB require external electron acceptors to regenerate NADH. The use of phenolic acids as external electron acceptors by the 4 FLAB showing the highest phenolic acid reductase activity was investigated in glucose-based medium supplemented with p-coumaric acid. Metabolic responses observed through a phenotypic microarray suggested that FLAB may use p-coumaric acid as an external electron acceptor, enhancing glucose dissimilation but less efficiently than other external acceptors such as fructose or pyruvic acid. IMPORTANCE Fructophilic lactic acid bacteria (FLAB) remain to be fully explored. This study intends to link unique biochemical features of FLAB with their habitat. The quite unique FLAB phenome within the group lactic acid bacteria (LAB) may have practical relevance

  16. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)

    2011-11-15

    Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  17. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    International Nuclear Information System (INIS)

    Cervantes, Francisco J.; Mancilla, Ana Rosa; Toro, E. Emilia Rios-del; Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia

    2011-01-01

    Highlights: → Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. → Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. → Several species from classes β-, δ- and γ-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 μM of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (μEq) L -1 , linked to the reduction of 619 ± 81 μEq L -1 of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two γ-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes β-, δ- and γ-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  18. Nitrate as electron acceptor in in situ abandoned refinery site bioremediation

    International Nuclear Information System (INIS)

    Battermann, G.; Meier-Loehr, M.

    1995-01-01

    The aquifer beneath an abandoned refinery site is highly polluted with benzene, toluene, ethylbenzene, and xylenes (BTEX). After removal of the free phase by hydraulic measures until 1986, the immobile residual concentration located 6 to 10 m beneath the surface is still present and causes hydrocarbon concentrations from 10 to 100 mg/L in the groundwater. Laboratory tests proved the biodegradability of the hydrocarbon compounds under denitrifying conditions. Based on the results of the pilot study, large-scale bioremediation covering an area of about 20 ha was initiated. About 500 m 3 /h of groundwater were extracted, and 400 m 3 /h were recharged. The large-scale plant has been operating since 1991. Nitrate as an electron acceptor has been used since 1992. About 300 metric tons (MT) of hydrocarbons have been removed to date. The area of groundwater pollution is diminished by a factor of about two. More than 60% of all groundwater observation wells are now free of dissolved hydrocarbons. In addition, the decrease of biological nitrate consumption gives evidence of advanced bioremediation of the soil

  19. Electron Acceptors Based on α-Substituted Perylene Diimide (PDI) for Organic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Donglin [Department; Wu, Qinghe [Department; Cai, Zhengxu [Department; Zheng, Tianyue [Department; Chen, Wei [Materials; Institute; Lu, Jessica [Department; Yu, Luping [Department

    2016-02-02

    Perylene diimide (PDI) derivatives functionalized at the ortho-position (αPPID, αPBDT) were synthesized and used as electron acceptors in non-fullerene organic photovoltaic cells. Because of the good planarity and strong π-stacking of ortho-functionalized PDI, the αPPID and αPBDT exhibit a strong tendency to form aggregates, which endow the materials with high electron mobility. The inverted OPVs employing αPDI-based compounds as the acceptors and PBT7-Th as the donor give the highest power conversion efficiency (PCE) values: 4.92% for αPBDT-based devices and 3.61% for αPPID-based devices, which are, respectively, 39% and 4% higher than that of their β-substituted counterparts βPBDT and βPPID. Charge separation studies show more efficient exciton dissociation at interfaces between αPDI-based compounds and PTB7-Th. The results suggest that α-substituted PDI derivatives are more promising electron acceptors for organic photovoltaic (OPV) components than β-isomers.

  20. Use of γ-hexachlorocyclohexane as a terminal electron acceptor by an anaerobic enrichment culture

    International Nuclear Information System (INIS)

    Elango, Vijai; Kurtz, Harry D.; Anderson, Christina; Freedman, David L.

    2011-01-01

    Highlights: ► Use of γ-hexachlorocyclohexane as a terminal electron acceptor was demonstrated. ► H 2 served as the electron donor for an enrichment culture that dechlorinated γ-HCH. ► H 2 consumption for acetogenesis and methanogenesis stopped in HEPES media. ► Addition of vancomycin significantly slowed the rate of γ-HCH dechlorination. ► Previously identified chlororespiring microbes were not detected in the enrichment. - Abstract: The use of γ-hexachlorocyclohexane (HCH) as a terminal electron acceptor via organohalide respiration was demonstrated for the first time with an enrichment culture grown in a sulfate-free HEPES-buffered anaerobic mineral salts medium. The enrichment culture was initially developed with soil and groundwater from an industrial site contaminated with HCH isomers, chlorinated benzenes, and chlorinated ethenes. When hydrogen served as the electron donor, 79–90% of the electron equivalents from hydrogen were used by the enrichment culture for reductive dechlorination of the γ-HCH, which was provided at a saturation concentration of approximately 10 mg/L. Benzene and chlorobenzene were the only volatile transformation products detected, accounting for 25% and 75% of the γ-HCH consumed (on a molar basis), respectively. The enrichment culture remained active with only hydrogen as the electron donor and γ-HCH as the electron acceptor through several transfers to fresh mineral salts medium for more than one year. Addition of vancomycin to the culture significantly slowed the rate of γ-HCH dechlorination, suggesting that a Gram-positive organism is responsible for the reduction of γ-HCH. Analysis of the γ-HCH dechlorinating enrichment culture did not detect any known chlororespiring genera, including Dehalobacter. In bicarbonate-buffered medium, reductive dechlorination of γ-HCH was accompanied by significant levels of acetogenesis as well as methanogenesis.

  1. Proton-coupled electron transfer from tryptophan: a concerted mechanism with water as proton acceptor.

    Science.gov (United States)

    Zhang, Ming-Tian; Hammarström, Leif

    2011-06-15

    The mechanism of proton-coupled electron transfer (PCET) from tyrosine in enzymes and synthetic model complexes is under intense discussion, in particular the pH dependence of the PCET rate with water as proton acceptor. Here we report on the intramolecular oxidation kinetics of tryptophan derivatives linked to [Ru(bpy)(3)](2+) units with water as proton acceptor, using laser flash-quench methods. It is shown that tryptophan oxidation can proceed not only via a stepwise electron-proton transfer (ETPT) mechanism that naturally shows a pH-independent rate, but also via another mechanism with a pH-dependent rate and higher kinetic isotope effect that is assigned to concerted electron-proton transfer (CEP). This is in contrast to current theoretical models, which predict that CEP from tryptophan with water as proton acceptor can never compete with ETPT because of the energetically unfavorable PT part (pK(a)(Trp(•)H(+)) = 4.7 ≫ pK(a)(H(3)O(+)) ≈ -1.5). The moderate pH dependence we observe for CEP cannot be explained by first-order reactions with OH(-) or the buffers and is similar to what has been demonstrated for intramolecular PCET in [Ru(bpy)(3)](3+)-tyrosine complexes (Sjödin, M.; et al. J. Am. Chem. Soc.2000, 122, 3932. Irebo, T.; et al. J. Am. Chem. Soc.2007, 129, 15462). Our results suggest that CEP with water as the proton acceptor proves a general feature of amino acid oxidation, and provide further experimental support for understanding of the PCET process in detail. © 2011 American Chemical Society

  2. Application of time release electron donors and electron acceptors for accelerated bioremediation

    International Nuclear Information System (INIS)

    Joksimovich, V.; Koenigsberg, S.

    2002-01-01

    Currently, there are limited options for cost effective approaches to soil and groundwater contamination. One technology that has proven its potential involves the use of time release electron acceptors to accelerate the natural bioattenuation of aerobically degradable compounds and time release electron donors to accelerate the natural bioattenuation of anaerobic compounds. This technology enjoys its reputations as a sensible strategy for engineering accelerated bioattenuation, because it delivers results while 1) limiting or eliminating design, capital and management costs and 2) allowing for the engineering of a low-impact application and a subsequently invisible remediation process. Oxygen Release Compound (ORC ) is proprietary formulation of intercalated magnesium peroxide that releases oxygen slowly, for about a year, and facilitates the aerobic degradation of a range of environmental contaminants including petroleum hydrocarbons, certain chlorinated hydrocarbons, ether oxygenates and nitroaromatics. The history of ORC's introduction and acceptance represents a model for the evolution of an innovative technology. This statement comes by virtue of the fact that since 1994 ORC has been used on over 7000 sites worldwide and has been the subject of an extensive body of literature. Hydrogen Release Compound (HRC) is also a proprietary polylactate ester that is food grade and, upon being deposited into the aquifer, is slowly hydrolyzed to release lactic acid and other organic acid derivatives for about one to two years. The organic acids are fermented to hydrogen, which in turn donates electrons that drive reductive bioattenuation processes. This is primarily directed at a wide range of chlorinated hydrocarbons, but can be applied to the remediation of metals by redox induced precipitation. HRC has now been used on over 220 sites, which we believe make it the most widely used electron donor for accelerating bioattenuation. ORC and HRC can be configured as a

  3. Long-Lived Charge Separation at Heterojunctions between Semiconducting Single-Walled Carbon Nanotubes and Perylene Diimide Electron Acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hyun Suk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Arias, Dylan H [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Blackburn, Jeffrey L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sisto, Thomas J. [Columbia University; Peurifoy, Samuel [Columbia University; Zhang, Boyuan [Columbia University; Nuckolls, Colin [Columbia University

    2018-04-13

    Nonfullerene electron acceptors have facilitated a recent surge in the efficiencies of organic solar cells, although fundamental studies of the nature of exciton dissociation at interfaces with nonfullerene electron acceptors are still relatively sparse. Semiconducting single-walled carbon nanotubes (s-SWCNTs), unique one-dimensional electron donors with molecule-like absorption and highly mobile charges, provide a model system for studying interfacial exciton dissociation. Here, we investigate excited-state photodynamics at the heterojunction between (6,5) s-SWCNTs and two perylene diimide (PDI)-based electron acceptors. Each of the PDI-based acceptors, hPDI2-pyr-hPDI2 and Trip-hPDI2, is deposited onto (6,5) s-SWCNT films to form a heterojunction bilayer. Transient absorption measurements demonstrate that photoinduced hole/electron transfer occurs at the photoexcited bilayer interfaces, producing long-lived separated charges with lifetimes exceeding 1.0 us. Both exciton dissociation and charge recombination occur more slowly for the hPDI2-pyr-hPDI2 bilayer than for the Trip-hPDI2 bilayer. To explain such differences, we discuss the potential roles of the thermodynamic charge transfer driving force available at each interface and the different molecular structure and intermolecular interactions of PDI-based acceptors. Detailed photophysical analysis of these model systems can develop the fundamental understanding of exciton dissociation between organic electron donors and nonfullerene acceptors, which has not been systematically studied.

  4. Tin-vacancy acceptor levels in electron-irradiated n-type silicon

    DEFF Research Database (Denmark)

    Larsen, A. Nylandsted; Goubet, J. J.; Mejlholm, P.

    2000-01-01

    annihilation. Two tin-vacancy (Sn-V) levels at E-c - 0.214 eV and E-c - 0.501 eV have been identified (E-c denotes the conduction band edge). Based on investigations of the temperature dependence of the electron-capture cross sections, the electric-field dependence of the electron emissivity, the anneal...... temperature, and the defect-introduction rate, it is concluded that these levels are the double and single acceptor levels, respectively, of the Sn-V pair. These conclusions are in agreement with electronic structure calculations carried out using a local spin-density functional theory, incorporating...... pseudopotentials to eliminate the core electrons, and applied to large H-terminated clusters. Thus, the Sn-V pair in Si has five different charge states corresponding to four levels in the band gap....

  5. Carbon gas production under different electron acceptors in a freshwater marsh soil.

    Science.gov (United States)

    Dodla, Syam K; Wang, Jim J; Delaune, Ronald D; Breitenbeck, Gary

    2009-07-01

    Dynamics of carbon (C) gas emission from wetlands influence global C cycling. In many freshwater systems such as Louisiana freshwater marsh, soil contents of NO3(-) and SO4(2-) have increased due to nutrient loading and saltwater intrusion. This could affect C mineralization and the emission of the major greenhouse gases carbon dioxide (CO2) and methane (CH4). In this investigation, a laboratory microcosm study was carried out to elucidate the effects of NO(3)(-) and SO4(2-) on CO2 and CH4 production from a freshwater marsh soil located in the Barataria Basin of Louisiana coast, which has been subjected to the Mississippi River diversion and seawater intrusion. Composite soil samples were collected from top 50 cm marsh profile, treated with different levels of NO3(-) (0, 3.2 and 5mM) or SO4(2-) (0, 2, and 5mM) concentrations, and incubated for 214d under anaerobic conditions. The results showed that the presence of NO3(-) (especially at 3.2mM) significantly decreased CO2 productions whereas SO4(2-) did not. On the other hand, both NO(3)(-) and SO4(2-) treatments decreased CH4 production but the NO3(-) almost completely inhibited CH4 production (>99%) whereas the SO4(2-) treatments reduced CH4 production by 78-90%. The overall C mineralization rate constant under the NO3(-) presence was also low. In addition, the results revealed that a large proportion (95%) of anaerobic carbon mineralization in the untreated freshwater soil was unexplained by the reduction of any of the measured major electron acceptors.

  6. Oligothiophene-S,S-dioxides as a class of electron-acceptor materials for organic photovoltaics

    International Nuclear Information System (INIS)

    Camaioni, N.; Ridolfi, G.; Fattori, V.; Favaretto, L.; Barbarella, G.

    2004-01-01

    Oligothiophene-S,S-dioxides are proposed as electron acceptors materials in organic blended photovoltaic devices. Photoinduced charge transfer is demonstrated in blends between a regioregular poly(3-hexylthiophene) and the oligomers, via photoluminescence spectroscopy. The enhanced photovoltaic performance exhibited by the blended cells, with respect to that of pristine devices in which the polymer is the active layer, represents further evidence for exciton dissociation. An increase of the power conversion efficiency up to sixty-fold is achieved by blending the polymer with the oligothiophene-S,S-dioxides

  7. Effects of different external carbon sources and electron acceptors on interactions between denitrification and phosphorus removal in biological nutrient removal processes.

    Science.gov (United States)

    Hu, Xiang; Sobotka, Dominika; Czerwionka, Krzysztof; Zhou, Qi; Xie, Li; Makinia, Jacek

    The effects of two different external carbon sources (acetate and ethanol) and electron acceptors (dissolved oxygen, nitrate, and nitrite) were investigated under aerobic and anoxic conditions with non-acclimated process biomass from a full-scale biological nutrient removal-activated sludge system. When acetate was added as an external carbon source, phosphate release was observed even in the presence of electron acceptors. The release rates were 1.7, 7.8, and 3.5 mg P/(g MLVSS·h) (MLVSS: mixed liquor volatile suspended solids), respectively, for dissolved oxygen, nitrate, and nitrite. In the case of ethanol, no phosphate release was observed in the presence of electron acceptors. Results of the experiments with nitrite showed that approximately 25 mg NO 2 -N/L of nitrite inhibited anoxic phosphorus uptake regardless of the concentration of the tested external carbon sources. Furthermore, higher denitrification rates were obtained with acetate (1.4 and 0.8 mg N/(g MLVSS·h)) compared to ethanol (1.1 and 0.7 mg N/ (g MLVSS·h)) for both anoxic electron acceptors (nitrate and nitrite).

  8. Electronic signal conditioning

    CERN Document Server

    NEWBY, BRUCE

    1994-01-01

    At technician level, brief references to signal conditioning crop up in a fragmented way in various textbooks, but there has been no single textbook, until now!More advanced texts do exist but they are more mathematical and presuppose a higher level of understanding of electronics and statistics. Electronic Signal Conditioning is designed for HNC/D students and City & Guilds Electronics Servicing 2240 Parts 2 & 3. It will also be useful for BTEC National, Advanced GNVQ, A-level electronics and introductory courses at degree level.

  9. Electron acceptors for anaerobic oxidation of methane drive microbial community structure and diversity in mud volcanoes.

    Science.gov (United States)

    Ren, Ge; Ma, Anzhou; Zhang, Yanfen; Deng, Ye; Zheng, Guodong; Zhuang, Xuliang; Zhuang, Guoqiang; Fortin, Danielle

    2018-04-06

    Mud volcanoes (MVs) emit globally significant quantities of methane into the atmosphere, however, methane cycling in such environments is not yet fully understood, as the roles of microbes and their associated biogeochemical processes have been largely overlooked. Here, we used data from high-throughput sequencing of microbial 16S rRNA gene amplicons from six MVs in the Junggar Basin in northwest China to quantify patterns of diversity and characterize the community structure of archaea and bacteria. We found anaerobic methanotrophs and diverse sulfate- and iron-reducing microbes in all of the samples, and the diversity of both archaeal and bacterial communities was strongly linked to the concentrations of sulfate, iron, and nitrate, which could act as electron acceptors in anaerobic oxidation of methane (AOM). The impacts of sulfate/iron/nitrate on AOM in the MVs were verified by microcosm experiments. Further, two representative MVs were selected to explore the microbial interactions based on phylogenetic molecular ecological networks. The sites showed distinct network structures, key species and microbial interactions, with more complex and numerous linkages between methane-cycling microbes and their partners being observed in the iron/sulfate-rich MV. These findings suggest that electron acceptors are important factors driving the structure of microbial communities in these methane-rich environments. This article is protected by copyright. All rights reserved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. A spiro-bifluorene based 3D electron acceptor with dicyanovinylene substitution for solution-processed non-fullerene organic solar cells

    KAUST Repository

    Xia, Debin

    2015-04-20

    A novel electron acceptor, namely 2,2′-(12H,12′H-10,10′-spirobi[indeno[2,1-b]fluorene]-12,12′-diylidene)dimalononitrile (4CN-spiro), exhibiting a three-dimensional molecular structure was synthesized and its thermal, photophysical, electrochemical, crystal, and photovoltaic properties were investigated. The novel acceptor exhibits excellent thermal stability with a decomposition temperature of 460 °C, an absorption extending to 600 nm, and a LUMO level of −3.63 eV. Solution processed bulk-heterojunction (BHJ) organic solar cells were fabricated using 4CN-spiro as an acceptor and polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) as a donor polymer. The effect of the donor-to-acceptor ratio and processing conditions on the device performance was investigated. A device processed from tetrachloroethane with a donor to acceptor weight ratio of 1 : 1 yielded a power conversion efficiency (PCE) of 0.80%.

  11. Fine-tuning of electronic properties in donor–acceptor conjugated polymers based on oligothiophenes

    Science.gov (United States)

    Imae, Ichiro; Sagawa, Hitoshi; Harima, Yutaka

    2018-03-01

    A novel series of donor–acceptor conjugated polymers having oligothiophenes with well-defined structures were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. It was found that the absorption bands of polymers were red-shifted with increasing number of ethylenedioxy groups added to each oligothiophene unit and that their band edges reached over 1000 nm. The systematical fine-tuning of the electronic properties was achieved using the chemical structures of oligothiophene units. Photovoltaic cells based on polymer/(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) exhibited power conversion efficiencies in the range from 0.004 to 1.10%, reflecting the electronic properties of the polymers.

  12. Regulation of Gene Expression in Shewanella oneidensis MR-1 during Electron Acceptor Limitation and Bacterial Nanowire Formation

    Science.gov (United States)

    Barchinger, Sarah E.; Pirbadian, Sahand; Baker, Carol S.; Leung, Kar Man; Burroughs, Nigel J.; El-Naggar, Mohamed Y.

    2016-01-01

    ABSTRACT In limiting oxygen as an electron acceptor, the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 rapidly forms nanowires, extensions of its outer membrane containing the cytochromes MtrC and OmcA needed for extracellular electron transfer. RNA sequencing (RNA-Seq) analysis was employed to determine differential gene expression over time from triplicate chemostat cultures that were limited for oxygen. We identified 465 genes with decreased expression and 677 genes with increased expression. The coordinated increased expression of heme biosynthesis, cytochrome maturation, and transport pathways indicates that S. oneidensis MR-1 increases cytochrome production, including the transcription of genes encoding MtrA, MtrC, and OmcA, and transports these decaheme cytochromes across the cytoplasmic membrane during electron acceptor limitation and nanowire formation. In contrast, the expression of the mtrA and mtrC homologs mtrF and mtrD either remains unaffected or decreases under these conditions. The ompW gene, encoding a small outer membrane porin, has 40-fold higher expression during oxygen limitation, and it is proposed that OmpW plays a role in cation transport to maintain electrical neutrality during electron transfer. The genes encoding the anaerobic respiration regulator cyclic AMP receptor protein (CRP) and the extracytoplasmic function sigma factor RpoE are among the transcription factor genes with increased expression. RpoE might function by signaling the initial response to oxygen limitation. Our results show that RpoE activates transcription from promoters upstream of mtrC and omcA. The transcriptome and mutant analyses of S. oneidensis MR-1 nanowire production are consistent with independent regulatory mechanisms for extending the outer membrane into tubular structures and for ensuring the electron transfer function of the nanowires. IMPORTANCE Shewanella oneidensis MR-1 has the capacity to transfer electrons to its external surface

  13. Exploring the Role of Persulfate in the Activation Process: Radical Precursor Versus Electron Acceptor.

    Science.gov (United States)

    Yun, Eun-Tae; Yoo, Ha-Young; Bae, Hyokwan; Kim, Hyoung-Il; Lee, Jaesang

    2017-09-05

    This study elucidates the mechanism behind persulfate activation by exploring the role of various oxyanions (e.g., peroxymonosulfate, periodate, and peracetate) in two activation systems utilizing iron nanoparticle (nFe 0 ) as the reducing agent and single-wall carbon nanotubes (CNTs) as electron transfer mediators. Since the tested oxyanions serve as both electron acceptors and radical precursors in most cases, oxidative degradation of organics was achievable through one-electron reduction of oxyanions on nFe 0 (leading to radical-induced oxidation) and electron transfer mediation from organics to oxyanions on CNTs (leading to oxidative decomposition involving no radical formation). A distinction between degradative reaction mechanisms of the nFe 0 /oxyanion and CNT/oxyanion systems was made in terms of the oxyanion consumption efficacy, radical scavenging effect, and EPR spectral analysis. Statistical study of substrate-specificity and product distribution implied that the reaction route induced on nFe 0 varies depending on the oxyanion (i.e., oxyanion-derived radical), whereas the similar reaction pathway initiates organic oxidation in the CNT/oxyanion system irrespective of the oxyanion type. Chronoamperometric measurements further confirmed electron transfer from organics to oxyanions in the presence of CNTs, which was not observed when applying nFe 0 instead.

  14. 2010 Electron Donor-Acceptor Interactions Gordon Research Conference, August 8 - 13, 2010.

    Energy Technology Data Exchange (ETDEWEB)

    Gerald Meyer

    2010-08-18

    The Gordon Research Conference on Electron Donor Acceptor Interactions (GRC EDAI) presents and advances the current frontiers in experimental and theoretical studies of Electron Transfer Processes and Energy Conversion. The fundamental concepts underpinning the field of electron transfer and charge transport phenomena are understood, but fascinating experimental discoveries and novel applications based on charge transfer processes are expanding the discipline. Simultaneously, global challenges for development of viable and economical alternative energy resources, on which many researchers in the field focus their efforts, are now the subject of daily news headlines. Enduring themes of this conference relate to photosynthesis, both natural and artificial, and solar energy conversion. More recent developments include molecular electronics, optical switches, and nanoscale charge transport structures of both natural (biological) and man-made origin. The GRC EDAI is one of the major international meetings advancing this field, and is one of the few scientific meetings where fundamental research in solar energy conversion has a leading voice. The program includes sessions on coupled electron transfers, molecular solar energy conversion, biological and biomimetic systems, spin effects, ultrafast reactions and technical frontiers as well as electron transport in single molecules and devices. In addition to disseminating the latest advances in the field of electron transfer processes, the conference is an excellent forum for scientists from different disciplines to meet and initiate new directions; for scientists from different countries to make contacts; for young scientists to network and establish personal contacts with other young scientists and with established scientists who, otherwise, might not have the time to meet young people. The EDAI GRC also features an interactive atmosphere with lively poster sessions, a few of which are selected for oral presentations.

  15. Critical review of the molecular design progress in non-fullerene electron acceptors towards commercially viable organic solar cells

    KAUST Repository

    Wadsworth, Andrew

    2018-04-26

    Fullerenes have formed an integral part of high performance organic solar cells over the last 20 years, however their inherent limitations in terms of synthetic flexibility, cost and stability have acted as a motivation to develop replacements; the so-called non-fullerene electron acceptors. A rapid evolution of such materials has taken place over the last few years, yielding a number of promising candidates that can exceed the device performance of fullerenes and provide opportunities to improve upon the stability and processability of organic solar cells. In this review we explore the structure-property relationships of a library of non-fullerene acceptors, highlighting the important chemical modifications that have led to progress in the field and provide an outlook for future innovations in electron acceptors for use in organic photovoltaics.

  16. Phenothiazine-Anthraquinone Donor-Acceptor Molecules: Synthesis, Electronic Properties and DFT-TDDFT Computational Study

    Science.gov (United States)

    Zhang, Wen-Wei; Mao, Wei-Li; Hu, Yun-Xia; Tian, Zi-Qi; Wang, Zhi-Lin; Meng, Qing-Jin

    2009-08-01

    Two donor-acceptor molecules with different π-electron conjugative units, 1-((10-methyl-10H-phenothiazin-3-yl)ethynyl)anthracene-9,10-dione (AqMp) and 1,1'-(10-methyl-10H-phenothiazine-3,7-diyl)bis(ethyne-2,1-diyl)dianthracene-9,10-dione (Aq2Mp), have been synthesized and investigated for their photochemical and electrochemical properties. Density functional theory (DFT) calculations provide insights into their molecular geometry, electronic structures, and properties. These studies satisfactorily explain the electrochemistry of the two compounds and indicate that larger conjugative effect leads to smaller HOMO-LUMO gap (Eg) in Aq2Mp. Both compounds show ICT and π → π* transitions in the UV-visible range in solution, and Aq2Mp has a bathochromic shift and shows higher oscillator strength of the absorption, which has been verified by time-dependent DFT (TDDFT) calculations. The differences between AqMp and Aq2Mp indicate that the structural and conjugative effects have great influence on the electronic properties of the molecules.

  17. High Hole-Mobility Molecular Layer Made from Strong Electron Acceptor Molecules with Metal Adatoms.

    Science.gov (United States)

    Yamane, Hiroyuki; Kosugi, Nobuhiro

    2017-11-02

    The electronic structure of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-TCNQ (F 4 TCNQ) monolayers on Au(111) has been investigated by means of angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation. In contrast to the physisorbed TCNQ/Au(111) interface, the high-resolution core-level photoemission spectra and the low-energy electron diffraction at the F 4 TCNQ/Au(111) interface show evidence for the strong charge transfer (CT) from Au to F 4 TCNQ and for the Au atom segregation from the underlying Au(111) surface, suggesting a possible origin of the spontaneous formation of the two-dimensional F 4 TCNQ-Au network. The ARPES experiment reveals a low hole-injection barrier and large band dispersion in the CT-induced topmost valence level of the F 4 TCNQ-Au network with 260 meV bandwidth due to the adatom-mediated intermolecular interaction. These results indicate that strong electron acceptor molecules with metal adatoms can form high hole-mobility molecular layers by controlling the molecule-metal ordered structure and their CT interaction.

  18. An Efficient, “Burn in” Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor

    KAUST Repository

    Cha, Hyojung

    2017-06-28

    A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3\\'″-di(2-octyldodecyl)-2,2\\';5\\',2″;5″,2\\'″-quaterthiophen-5,5\\'″-diyl)] (PffBT4T-2OD) as a donor polymer blended with either the nonfullerene acceptor EH-IDTBR or the fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) as electron acceptors is reported. Inverted PffBT4T-2OD:EH-IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH-IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T-2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T-2OD:PC71 BM solar cells show significant efficiency loss under simulated solar irradiation (“burn in” degradation) due to the trap-assisted recombination through increased photoinduced trap states, PffBT4T-2OD:EH-IDTBR solar cell shows negligible burn in efficiency loss. Furthermore, PffBT4T-2OD:EH-IDTBR solar cells are found to be substantially more stable under 85 °C thermal stress than PffBT4T-2OD:PC71BM devices.

  19. An Efficient, "Burn in" Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor.

    Science.gov (United States)

    Cha, Hyojung; Wu, Jiaying; Wadsworth, Andrew; Nagitta, Jade; Limbu, Saurav; Pont, Sebastian; Li, Zhe; Searle, Justin; Wyatt, Mark F; Baran, Derya; Kim, Ji-Seon; McCulloch, Iain; Durrant, James R

    2017-09-01

    A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'″-di(2-octyldodecyl)-2,2';5',2″;5″,2'″-quaterthiophen-5,5'″-diyl)] (PffBT4T-2OD) as a donor polymer blended with either the nonfullerene acceptor EH-IDTBR or the fullerene derivative, [6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM) as electron acceptors is reported. Inverted PffBT4T-2OD:EH-IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH-IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T-2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T-2OD:PC 71 BM solar cells show significant efficiency loss under simulated solar irradiation ("burn in" degradation) due to the trap-assisted recombination through increased photoinduced trap states, PffBT4T-2OD:EH-IDTBR solar cell shows negligible burn in efficiency loss. Furthermore, PffBT4T-2OD:EH-IDTBR solar cells are found to be substantially more stable under 85 °C thermal stress than PffBT4T-2OD:PC 71 BM devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Structural and optical properties of langmuir-blodgett films of the electron acceptor 2-octadecylthio-1,4-benzoquinone

    DEFF Research Database (Denmark)

    Bjørnholm, T.; Larsen, N. B.; Christensen, Finn Erland

    1993-01-01

    The electron acceptor 2-octadecylthio-1,4-benzoquinone forms stable monolayers at air/water interfaces. Transfer to hydrophobic substrates yields Y-type Langmuir-Blodgett films. By studies of multilayers using X-ray diffraction and spectroscopy with polarized light a structure model is obtained...

  1. Utilization of toxic and vapors as alternate electron acceptors in biofilters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.D.; Apel, W.A.; Walton, M.R.

    1997-08-01

    Conceptually, biofilters are vapor phase bioreactors that rely on microorganisms in the bed medium to oxidize contaminants in off-gases flowing through the bed to less hazardous compounds. In the most studied and utilized systems reduced compounds such as fuel hydrocarbons are enzymatically oxidized to compounds such as carbon dioxide and water. In these types of reactions the microorganisms in the bed oxidize the contaminant and transfer the electrons to oxygen which is the terminal electron acceptor in the process. In essence the contaminant is the carbon and energy source for the microorganisms in the bed medium and through this catabolic process oxygen is reduced to water. An example of this oxidation process can be seen during the degradation of benzene and similar aromatic compounds. Aromatics are initially attacked by a dioxygenase enzyme which oxidizes the compounds to a labile dihydrodiole which is spontaneously converted to a catechol. The dihydroxylated aromatic rings is then opened by oxidative {open_quotes}ortho{close_quotes} or {open_quotes}meta{close_quotes} cleavage yielding cis, cis-muconic acid or 2-hydroxy-cis, cis-muconic semialdehyde, respectively. These organic compounds are further oxidized to carbon dioxide or are assimilated for cellular material. This paper describes the conversion of carbon tetrachloride using methanol as the primary carbon and energy source.

  2. A combined study of mesomorphism, optical, and electronic properties of donor-acceptor columnar liquid crystals

    NARCIS (Netherlands)

    Eichhorn, S.H.; Shuai, C.; Ahmida, M.; Demenev, A.; Kayal, H.; Raad, F.S.; Kaafarani, B.R.; Patwardhan, S.; Grozema, F.C.; Siebbeles, L.D.A.; Taerum, T.; Perepichka, D.F.; Klenkler, R.

    2011-01-01

    Donor-acceptor structures have recently gained great popularity for the design of low band gap polymeric organic semiconductors. Presented here is a first systematic study of organic semiconductors based on columnar liquid crystals that consist of discotic and board-shaped donor-acceptor structures.

  3. An effective Hamiltonian approach for Donor-Bridge-Acceptor electronic transitions: Exploring the role of bath memory

    Directory of Open Access Journals (Sweden)

    E.R. Bittner

    2016-03-01

    Full Text Available We present here a formally exact model for electronic transitions between an initial (donor and final (acceptor states linked by an intermediate (bridge state. Our model incorporates a common set of vibrational modes that are coupled to the donor, bridge, and acceptor states and serves as a dissipative bath that destroys quantum coherence between the donor and acceptor. Taking the memory time of the bath as a free parameter, we calculate transition rates for a heuristic 3-state/2 mode Hamiltonian system parameterized to represent the energetics and couplings in a typical organic photovoltaic system. Our results indicate that if the memory time of the bath is of the order of 10-100 fs, a two-state kinetic (i.e., incoherent hopping model will grossly underestimate overall transition rate.

  4. Changes in phosphorylation of adenosine phosphate and redox state of nicotinamide-adenine dinucleotide (phosphate) in Geobacter sulfurreducens in response to electron acceptor and anode potential variation

    KAUST Repository

    Rose, Nicholas D.

    2015-12-01

    © 2015 Elsevier B.V. Geobacter sulfurreducens is one of the dominant bacterial species found in biofilms growing on anodes in bioelectrochemical systems. The intracellular concentrations of reduced and oxidized forms of nicotinamide-adenine dinucleotide (NADH and NAD+, respectively) and nicotinamide-adenine dinucleotide phosphate (NADPH and NADP+, respectively) as well as adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) were measured in G. sulfurreducens using fumarate, Fe(III)-citrate, or anodes poised at different potentials (110, 10, -90, and -190mV (vs. SHE)) as the electron acceptor. The ratios of CNADH/CNAD+ (0.088±0.022) and CNADPH/CNADP+ (0.268±0.098) were similar under all anode potentials tested and with Fe(III)-citrate (reduced extracellularly). Both ratios significantly increased with fumarate as the electron acceptor (0.331±0.094 for NAD and 1.96±0.37 for NADP). The adenylate energy charge (the fraction of phosphorylation in intracellular adenosine phosphates) was maintained near 0.47 under almost all conditions. Anode-growing biofilms demonstrated a significantly higher molar ratio of ATP/ADP relative to suspended cultures grown on fumarate or Fe(III)-citrate. These results provide evidence that the cellular location of reduction and not the redox potential of the electron acceptor controls the intracellular redox potential in G. sulfurreducens and that biofilm growth alters adenylate phosphorylation.

  5. Effects of donor-acceptor electronic interactions on the rates of gas-phase metallocene electron-exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, D.K.; Gord, J.R.; Freiser, B.S.; Weaver, M.J. (Purdue Univ., West Lafayette, IN (United States))

    1991-05-30

    Rate constants for electron self-exchange, k{sub ex}, of five cobaltocenium-cobaltocene and ferrocenium-ferrocene couples in the gas phase have been measured by means of Fourier transform ion cyclotron resonance mass spectrometry in order to explore the possible effects of donor-acceptor electronic coupling on gas-phase redox reactivity. The systems studied, Cp{sub 2}Co{sup +/0}, Cp{sub 2}Fe{sup +/0} (Cp = cyclopentadienyl), the decamethyl derivative Cp{prime}{sub 2}Fe{sup +/0}, carboxymethyl(cobaltocenium-cobaltocene) (Cp{sub 2}{sup e}Co{sup +/0}), and hydroxymethyl(ferrocenium-ferrocene) (HMFc{sup +/0}), were selected in view of the substantial variations in electronic coupling inferred on the basis of their solvent-dependent reactivities and theoretical grounds. The sequence of k{sub ex} values determined in the gas phase, Cp{sub 2}{sup e}Co{sup +/0} {approx} Cp{sub 2}Co{sup +/0} > Cp{prime}{sub 2}Fe{sup +/0} > HMFc{sup +/0} > Cp{sub 2}Fe{sup +/0}, is roughly similar to that observed in solution, although the magnitude (up to 5-fold) of the k{sub ex} variations is smaller in the former case. The likely origins of these differences in gas-phase reactivity are discussed in light of the known variations in the electronic coupling matrix element H{sub 12}, inner-shell reorganization energy {Delta}E*, and gas-phase ion-molecule interaction energy {Delta}E{sub w} extracted from solution-phase rates, structural data, and theoretical calculations. It is concluded that the observed variations in gas-phase k{sub ex} values, especially for Cp{sub 2}Fe{sup +/0} versus Cp{sub 2}Co{sup +/0}, arise predominantly from the presence of weaker donor-acceptor orbital overlap for the ferrocene couples, yielding inefficient electron tunneling for a substantial fraction of the gas-phase ion-molecule encounters. The anticipated differences as well as similarities of such nonadiabatic effects for gas-phase and solution electron-transfer processes are briefly outlined.

  6. Land cover controls the export of terminal electron acceptors from boreal catchments

    Science.gov (United States)

    Palviainen, Marjo; Lehtoranta, Jouni; Ekholm, Petri; Ruoho-Airola, Tuija; Kortelainen, Pirkko

    2015-04-01

    NO3, Mn, Fe and SO4 act as terminal electron acceptors (TEAs) modifying mineralization pathways and coupling biogeochemical cycles. Although single TEA concentrations and fluxes have been intensively studied, the factors regulating the simultaneous fluxes and molar ratios of TEAs are poorly elucidated. We studied the mean concentrations, exports and molar ratios of TEAs from 27 boreal catchments differing in land cover (percentage of agricultural land, peatland, forest and built-up area) in the years 2000-2011. TEA exports and molar ratios were strongly controlled by land cover and only little by atmospheric deposition. There were a great variability of the export of TEAs from different land cover classes. Fields produced the highest export of TEAs, particularly NO3. Peatland was linked to low NO3 and SO4 but high Fe exports. NO3, Mn and Fe exports from forests were low, SO4 having proportionally the highest export. Together, the percentages of field and peatland predicted 93%, 80%, 75% and 67% of the variation in the export of NO3, Mn, Fe and SO4, respectively. Our results showed that the export and molar ratios of TEAs in northern European boreal catchments are predominantly a function of land cover and catchment processes rather than atmospheric deposition. The variable export of TEAs having different availability and physical behavior may create different premises for anaerobic mineralization in downstream systems, which adds a new dimension to the link between terrestrial system, land use and environmental problems such as eutrophication and climate change.

  7. Transcriptional analysis of Shewanella oneidensis MR-1 with an electrode compared to Fe(IIIcitrate or oxygen as terminal electron acceptor.

    Directory of Open Access Journals (Sweden)

    Miriam A Rosenbaum

    Full Text Available Shewanella oneidensis is a target of extensive research in the fields of bioelectrochemical systems and bioremediation because of its versatile metabolic capabilities, especially with regard to respiration with extracellular electron acceptors. The physiological activity of S. oneidensis to respire at electrodes is of great interest, but the growth conditions in thin-layer biofilms make physiological analyses experimentally challenging. Here, we took a global approach to evaluate physiological activity with an electrode as terminal electron acceptor for the generation of electric current. We performed expression analysis with DNA microarrays to compare the overall gene expression with an electrode to that with soluble iron(III or oxygen as the electron acceptor and applied new hierarchical model-based statistics for the differential expression analysis. We confirmed the differential expression of many genes that have previously been reported to be involved in electrode respiration, such as the entire mtr operon. We also formulate hypotheses on other possible gene involvements in electrode respiration, for example, a role of ScyA in inter-protein electron transfer and a regulatory role of the cbb3-type cytochrome c oxidase under anaerobic conditions. Further, we hypothesize that electrode respiration imposes a significant stress on S. oneidensis, resulting in higher energetic costs for electrode respiration than for soluble iron(III respiration, which fosters a higher metabolic turnover to cover energy needs. Our hypotheses now require experimental verification, but this expression analysis provides a fundamental platform for further studies into the molecular mechanisms of S. oneidensis electron transfer and the physiologically special situation of growth on a poised-potential surface.

  8. Decacyclene Trianhydride at Functional Interfaces: An Ideal Electron Acceptor Material for Organic Electronics

    DEFF Research Database (Denmark)

    de Oteyza, Dimas G.; García Lastra, Juan Maria; Toma, Francesca M.

    2016-01-01

    We report the interface energetics of decacyclene trianhydride (DTA) monolayers on top of two distinct model surfaces, namely, Au(111) and Ag(111). On the latter, combined valence band photoemission and X-ray absorption measurements that access the occupied and unoccupied molecular orbitals......, respectively, reveal that electron transfer from substrate to surface sets in. Density functional theory calculations confirm our experimental findings and provide an understanding not only of the photoemission and X-ray absorption spectral features of this promising organic semiconductor but also...

  9. Organic donor-acceptor thin film systems. Towards optimized growth conditions

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Kerstin Andrea

    2009-06-30

    In this work the preparation of organic donor-acceptor thin films was studied. A chamber for organic molecular beam deposition was designed and integrated into an existing deposition system for metallic thin films. Furthermore, the deposition system was extended by a load-lock with integrated bake-out function, a chamber for the deposition of metallic contacts via stencil mask technique and a sputtering chamber. For the sublimation of the organic compounds several effusion cells were designed. The evaporation characteristic and the temperature profile within the cells was studied. Additionally, a simulation program was developed, which calculates the evaporation characteristics of different cell types. The following processes were integrated: evaporation of particles, migration on the cell walls and collisions in the gas phase. It is also possible to consider a temperature gradient within the cell. All processes can be studied separately and their relative strength can be varied. To verify the simulation results several evaporation experiments with different cell types were employed. The thickness profile of the prepared thin films was measured position-dependently. The results are in good agreement with the simulation. Furthermore, the simulation program was extended to the field of electron beam induced deposition (EBID). The second part of this work deals with the preparation and characterization of organic thin films. The focus hereby lies on the charge transfer salt (BEDT-TTF)(TCNQ), which has three known structure variants. Thin films were prepared by different methods of co-evaporation and were studied with optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy (EDX).The formation of the monoclinic phase of (BEDT-TTF)(TCNQ) could be shown. As a last part tunnel structures were prepared as first thin film devices and measured in a He{sub 4} cryostat. (orig.)

  10. Enhanced biological phosphorus removal. Carbon sources, nitrate as electron acceptor, and characterization of the sludge community

    Energy Technology Data Exchange (ETDEWEB)

    Christensson, M.

    1997-10-01

    Enhanced biological phosphorus removal (EBPR) was studied in laboratory scale experiments as well as in a full scale EBPR process. The studies were focused on carbon source transformations, the use of nitrate as an electron acceptor and characterisation of the microflora. A continuous anaerobic/aerobic laboratory system was operated on synthetic wastewater with acetate as sole carbon source. An efficient EBPR was obtained and mass balances over the anaerobic reactor showed a production of 1.45 g poly-{beta}-hydroxyalcanoic acids (PHA), measured as chemical oxygen demand (COD), per g of acetic acid (as COD) taken up. Furthermore, phosphate was released in the anaerobic reactor in a ratio of 0.33 g phosphorus (P) per g PHA (COD) formed and 0.64 g of glycogen (COD) was consumed per g of acetic acid (COD) taken up. Microscopic investigations revealed a high amount of polyphosphate accumulating organisms (PAO) in the sludge. Isolation and characterisation of bacteria indicated Acinetobacter spp. to be abundant in the sludge, while sequencing of clones obtained in a 16S rDNA clone library showed a large part of the bacteria to be related to the high mole % G+C Gram-positive bacteria and only a minor fraction to be related to the gamma-subclass of proteobacteria to which Acinetobacter belongs. Operation of a similar anaerobic/aerobic laboratory system with ethanol as sole carbon source showed that a high EBPR can be achieved with this compound as carbon source. However, a prolonged detention time in the anaerobic reactor was required. PHA were produced in the anaerobic reactor in an amount of 1.24 g COD per g of soluble DOC taken up, phosphate was released in an amount of 0.4-0.6 g P per g PHA (COD) produced and 0.46 g glycogen (COD) was consumed per g of soluble COD taken up. Studies of the EBPR in the UCT process at the sewage treatment plant in Helsingborg, Sweden, showed the amount of volatile fatty acids (VFA) available to the PAO in the anaerobic stage to be

  11. Characterization by time-resolved UV/Vis and infrared absorption spectroscopy of an intramolecular charge-transfer state in an organic electron-donor-bridge-acceptor system

    NARCIS (Netherlands)

    Hviid, L.; Verhoeven, J.W.; Brouwer, A.M.; Paddon-Row, M.N.; Yang, J.

    2004-01-01

    A long-lived intramolecular charge-separated state in an electron-donor-acceptor molecule is characterized by time-resolved visible and infrared absorption spectroscopy. Bands that can be assigned to the negatively charged acceptor chromophore can be clearly observed in the time-resolved IR

  12. Ultrafast responses of dipolar and octupolar compounds with dipicolinate as an electron acceptor

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaochuan, E-mail: ycwang@dlmu.edu.cn [Department of Physics, Dalian Maritime University, Dalian 116026 (China); State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Liu, Siyuan; Liu, Dajun; Wang, Guiqiu [Department of Physics, Dalian Maritime University, Dalian 116026 (China); Xiao, Haibo [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China)

    2016-11-01

    Two dipolar compounds with dipicolinate as electron acceptor group named trans-dimethyl-4-[4’-(N,N-dimethylamino)-styry1]-pyridin-2,6-dicarboxylate (M-1), trans-dimethyl-4-[4'-(N,N-diphenylamino)-styry1]-pyridin-2,6-dicarboxylate (P-1) as well as a P-1 based multi-branched octupolar compound {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl) vinyl]}-N,N-bis{4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinylphenyl]} aniline (P-3) with intense two-photon fluorescence emission properties are systematically investigated by using steady-state absorption and fluorescence spectroscopy, Z-scan, and two-photon excited fluorescence (TPF) method. The two-photon absorption cross section of octupolar compound P-3 in THF solution is determined to be 376 GM, which is approximately 12 times greater than that of dipolar counterpart P-1 (32 GM). Transient absorption spectroscopy is employed to investigate the excited state dynamics of the dipolar and octupolar compounds. The formation and relaxation lifetimes of the intra-molecular charge transfer (ICT) state are determined to be in the ranges of several picoseconds and several-hundreds of picoseconds, respectively, for all the three compounds in THF solutions. An extended π-conjugated system and increased intra-molecular cooperative effect are responsible for the observed large two-photon absorption character. - Highlights: • Octupolar compound gain 12-fold enhancement of two photon absorption. • Dynamic properties of intra-molecular charge transfer state are determined. • Cooperative effect is responsible for great increase of two photon character.

  13. Kinetic modeling of electron transfer reactions in photosystem I complexes of various structures with substituted quinone acceptors.

    Science.gov (United States)

    Milanovsky, Georgy E; Petrova, Anastasia A; Cherepanov, Dmitry A; Semenov, Alexey Yu

    2017-09-01

    The reduction kinetics of the photo-oxidized primary electron donor P 700 in photosystem I (PS I) complexes from cyanobacteria Synechocystis sp. PCC 6803 were analyzed within the kinetic model, which considers electron transfer (ET) reactions between P 700 , secondary quinone acceptor A 1 , iron-sulfur clusters and external electron donor and acceptors - methylviologen (MV), 2,3-dichloro-naphthoquinone (Cl 2 NQ) and oxygen. PS I complexes containing various quinones in the A 1 -binding site (phylloquinone PhQ, plastoquinone-9 PQ and Cl 2 NQ) as well as F X -core complexes, depleted of terminal iron-sulfur F A /F B clusters, were studied. The acceleration of charge recombination in F X -core complexes by PhQ/PQ substitution indicates that backward ET from the iron-sulfur clusters involves quinone in the A 1 -binding site. The kinetic parameters of ET reactions were obtained by global fitting of the P 700 + reduction with the kinetic model. The free energy gap ΔG 0 between F X and F A /F B clusters was estimated as -130 meV. The driving force of ET from A 1 to F X was determined as -50 and -220 meV for PhQ in the A and B cofactor branches, respectively. For PQ in A 1A -site, this reaction was found to be endergonic (ΔG 0  = +75 meV). The interaction of PS I with external acceptors was quantitatively described in terms of Michaelis-Menten kinetics. The second-order rate constants of ET from F A /F B , F X and Cl 2 NQ in the A 1 -site of PS I to external acceptors were estimated. The side production of superoxide radical in the A 1 -site by oxygen reduction via the Mehler reaction might comprise ≥0.3% of the total electron flow in PS I.

  14. Metabolism of fructophilic lactic acid bacteria isolated from Apis mellifera L. bee-gut: a focus on the phenolic acids as external electron acceptors.

    Science.gov (United States)

    Filannino, Pasquale; Di Cagno, Raffaella; Addante, Rocco; Pontonio, Erica; Gobbetti, Marco

    2016-09-16

    Fructophilic lactic acid bacteria (FLAB) are strongly associated to the gastrointestinal tract (GIT) of Apis mellifera L. worker bees due to the consumption of fructose as a major carbohydrate. Seventy-seven presumptive lactic acid bacteria (LAB) were isolated from GIT of healthy A. mellifera L. adults, which were collected from 5 different geographical locations of Apulia region (Italy). Almost all the isolates showed fructophilic tendencies, which were identified as Lactobacillus kunkeei (69%) or Fructobacillus fructosus (31%). A high-throughput phenotypic microarray, targeting 190 carbon sources, was used to determine that 83 compounds were differentially consumed. Phenotyping grouped the strains into two clusters, reflecting growth performance. The utilization of phenolic acids, such as p-coumaric, caffeic, syringic or gallic acids, as electron acceptors was investigated in fructose based medium. Almost all FLAB strains showed tolerance to high phenolic acid concentrations. p-Coumaric acid and caffeic acid were consumed by all FLAB strains through reductases or decarboxylases. Syringic and gallic acids were partially metabolized. The data collected suggest that FLAB require external electron acceptors to regenerate NADH. The use of phenolic acids as external electron acceptors by 4 FLAB, showing the highest phenolic acid reductase activity, was investigated in glucose based medium supplemented with p-coumaric acid. Metabolic responses observed through phenotypic microarray suggested that FLAB may use p-coumaric acid as external electron acceptor, enhancing glucose dissimilation but less efficiently than other external acceptors such as fructose or pyruvic acid. Fructophilic lactic acid bacteria (FLAB) remain to be fully explored. This study intends to link unique biochemical features of FLAB with their habitat. The quite unique FLAB phenome within the lactic acid bacteria (LAB) group may have practical relevance in food fermentations. The FLAB phenome may have

  15. Microbial fuel cell operation using monoazo and diazo dyes as terminal electron acceptor for simultaneous decolourisation and bioelectricity generation

    Energy Technology Data Exchange (ETDEWEB)

    Oon, Yoong-Sin [Water Research Group (WAREG), School of Environmental Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis (Malaysia); Ong, Soon-An, E-mail: ongsoonan@yahoo.com [Water Research Group (WAREG), School of Environmental Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis (Malaysia); Ho, Li-Ngee [School of Materials Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis (Malaysia); Wong, Yee-Shian; Oon, Yoong-Ling; Lehl, Harvinder Kaur; Thung, Wei-Eng [Water Research Group (WAREG), School of Environmental Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis (Malaysia); Nordin, Noradiba [School of Materials Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis (Malaysia)

    2017-03-05

    Highlights: • Monoazo and diazo dyes were used as electron acceptor in the abiotic cathode of MFC. • Simultaneous decolourisation and bioelectricity generation were achieved. • Azo dye structures influenced the decolourisation performance. • Positive relation between decolourisation rate and power performance. - Abstract: Monoazo and diazo dyes [New coccine (NC), Acid orange 7 (AO7), Reactive red 120 (RR120) and Reactive green 19 (RG19)] were employed as electron acceptors in the abiotic cathode of microbial fuel cell. The electrons and protons generated from microbial organic oxidation at the anode which were utilized for electrochemical azo dye reduction at the cathodic chamber was successfully demonstrated. When NC was employed as the electron acceptor, the chemical oxygen demand (COD) removal and dye decolourisation efficiencies obtained at the anodic and cathodic chamber were 73 ± 3% and 95.1 ± 1.1%, respectively. This study demonstrated that the decolourisation rates of monoazo dyes were ∼50% higher than diazo dyes. The maximum power density in relation to NC decolourisation was 20.64 mW/m{sup 2}, corresponding to current density of 120.24 mA/m{sup 2}. The decolourisation rate and power output of different azo dyes were in the order of NC > AO7 > RR120 > RG19. The findings revealed that the structure of dye influenced the decolourisation and power performance of MFC. Azo dye with electron-withdrawing group at para substituent to azo bond would draw electrons from azo bond; hence the azo dye became more electrophilic and more favourable for dye reduction.

  16. Usage of ferrum (ІІІ and manganese (IV ions as electron acceptors by Desulfuromonas sp. bacteria

    Directory of Open Access Journals (Sweden)

    O. M. Moroz

    2016-03-01

    Full Text Available The toxicity of metal ions to microorganisms, in particular at high concentrations, is one of the main impediments to their usage in remediation technologies. The purpose of this work is to analyze the possibility of usage by bacteria of the Desulfuromonas genus, isolated by us from Yavorivske Lake, of ferrum (ІІІ and manganese (IV ions at concentrations in the medium of 1,74–10,41 mM as electron acceptors of anaerobic respiration to assesss resistance of sulphur reducing bacteria strains to heavy metal compounds. Cells of Desulfuromonas acetoxidans ІМV V-7384, Desulfuromonas sp. Yavor-5 and Desulfuromonas sp. Yavor-7 were cultivated for 10 days at 30 °C under anaerobic conditions in Kravtsov-Sorokin’s medium without sulphate ions, sulphur, with cysteine as the sulphur source (0.2 g/l and sodium lactate or citrate as the electron donor (17.86 g/l, in which were added sterile 1 M solutions of C6H5O7Fe and C4H4O4 (control and also weights of MnO2 to their terminal concentrations 1.74, 3.47, 5.21, 6.94, 10.41 mM. Biomass was determined by the turbidimetric method. In the culture liquid the presence of Fe3+ and Mn4+ were qualitatively determined, and the content of Fe2+ in reaction with о-phenanthroline was determined quantitatively. It was established that sulphur reducing bacteria used with different intensity ferrum (ІІІ and manganese (IV ions as electron acceptors during the process of anaerobic respiration at concentrations of 1.74–10.41 mM C6H5O7Fe and MnO2 in the medium, which demonstrated the important role of the investigated microorganisms in reductive detoxication of natural and technogenic media from oxidized forms of transitional heavy metals. An insignificant difference in biomass accumulation during usage of 5.21–10.41 mM ferrum (ІІІ ions and fumarate is caused by toxicity of the metal ions to cells since the high redox potential of the Fe(III/Fe(ІІ pair with increase in concentrations of electron acceptors in

  17. Enantiopure versus Racemic Naphthalimide End-Capped Helicenic Non-fullerene Electron Acceptors: Impact on Organic Photovoltaics Performance.

    Science.gov (United States)

    Josse, Pierre; Favereau, Ludovic; Shen, Chengshuo; Dabos-Seignon, Sylvie; Blanchard, Philippe; Cabanetos, Clément; Crassous, Jeanne

    2017-05-05

    Impact of the enantiopurity on organic photovoltaics (OPV) performance was investigated through the synthesis of racemic and enantiomerically pure naphthalimide end-capped helicenes and their application as non-fullerene molecular electron acceptors in OPV devices. A very strong increase of the device performance was observed by simply switching from the racemic to the enantiopure forms of these π-helical non-fullerene acceptors with power conversion efficiencies jumping from 0.4 to about 2.0 % in air-processed poly(3-hexylthiophene)-based devices, thus highlighting the key role of enantiopurity in the photovoltaic properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Hydroxycinnamic acids used as external acceptors of electrons: an energetic advantage for strictly heterofermentative lactic acid bacteria.

    Science.gov (United States)

    Filannino, Pasquale; Gobbetti, Marco; De Angelis, Maria; Di Cagno, Raffaella

    2014-12-01

    The metabolism of hydroxycinnamic acids by strictly heterofermentative lactic acid bacteria (19 strains) was investigated as a potential alternative energy route. Lactobacillus curvatus PE5 was the most tolerant to hydroxycinnamic acids, followed by strains of Weissella spp., Lactobacillus brevis, Lactobacillus fermentum, and Leuconostoc mesenteroides, for which the MIC values were the same. The highest sensitivity was found for Lactobacillus rossiae strains. During growth in MRS broth, lactic acid bacteria reduced caffeic, p-coumaric, and ferulic acids into dihydrocaffeic, phloretic, and dihydroferulic acids, respectively, or decarboxylated hydroxycinnamic acids into the corresponding vinyl derivatives and then reduced the latter compounds to ethyl compounds. Reductase activities mainly emerged, and the activities of selected strains were further investigated in chemically defined basal medium (CDM) under anaerobic conditions. The end products of carbon metabolism were quantified, as were the levels of intracellular ATP and the NAD(+)/NADH ratio. Electron and carbon balances and theoretical ATP/glucose yields were also estimated. When CDM was supplemented with hydroxycinnamic acids, the synthesis of ethanol decreased and the concentration of acetic acid increased. The levels of these metabolites reflected on the alcohol dehydrogenase and acetate kinase activities. Overall, some biochemical traits distinguished the common metabolism of strictly heterofermentative strains: main reductase activity toward hydroxycinnamic acids, a shift from alcohol dehydrogenase to acetate kinase activities, an increase in the NAD(+)/NADH ratio, and the accumulation of supplementary intracellular ATP. Taken together, the above-described metabolic responses suggest that strictly heterofermentative lactic acid bacteria mainly use hydroxycinnamic acids as external acceptors of electrons. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  19. Positronium Inhibition and Quenching by Organic Electron Acceptors and Charge Transfer Complexes

    DEFF Research Database (Denmark)

    Jansen, P.; Eldrup, Morten Mostgaard; Jensen, Bror Skytte

    1975-01-01

    the inhibition intensifies and the quenching almost vanishes. The reaction constants between ortho-Ps and the acceptors were determinded to be: 1.5 × 1010 M−1 s−1 for SO2 in dioxane 3.7 × 1010 M−1 s−1 for SO2 in n-heptane, 3.4 × 1010 M−1 s−1 for tetracyanoquinodimethane in tetrahydrofurane and 1.6 × 1010 M−1 s−1...

  20. Donor–Acceptor Copolymers of Relevance for Organic Photovoltaics: A Theoretical Investigation of the Impact of Chemical Structure Modifications on the Electronic and Optical Properties

    KAUST Repository

    Pandey, Laxman

    2012-08-28

    We systematically investigate at the density functional theory level how changes to the chemical structure of donor-acceptor copolymers used in a number of organic electronics applications influences the intrinsic geometric, electronic, and optical properties. We consider the combination of two distinct donors, where a central five-membered ring is fused on both sides by either a thiophene or a benzene ring, with 12 different acceptors linked to the donor either directly or through thienyl linkages. The interplay between the electron richness/deficiency of the subunits as well as the evolution of the frontier electronic levels of the isolated donors/acceptors plays a significant role in determining the electronic and optical properties of the copolymers. © 2012 American Chemical Society.

  1. Fluorescent carbon quantum dots synthesized by chemical vapor deposition: An alternative candidate for electron acceptor in polymer solar cells

    Science.gov (United States)

    Cui, Bo; Yan, Lingpeng; Gu, Huimin; Yang, Yongzhen; Liu, Xuguang; Ma, Chang-Qi; Chen, Yongkang; Jia, Husheng

    2018-01-01

    Excitation-wavelength-dependent blue-greenish fluorescent carbon quantum dots (CQDs) with graphite structure were synthesized by chemical vapor deposition (CVD) method. In comparison with those synthesized by hydrothermal method (named H-CQDs), C-CQDs have less hydrophilic terminal groups, showing good solubility in common organic solvents. Furthermore, these synthesized C-CQDs show a low LUMO energy level (LUMO = -3.84 eV), which is close to that of phenyl-C61-butyric acid methyl ester (PC61BM, LUMO = -4.01 eV), the most widely used electron acceptor in polymer solar cells. Photoluminescence quenching of the poly(3-hexylthiophene-2,5-diyl):C-CQDs blended film (P3HT:C-CQDs) indicated that a photo-induced charge transfer between P3HT and C-CQDs occurs in such a composite film. Bulk heterojunction solar cells using C-CQDs as electron acceptors or doping materials were fabricated and tested. High fill factors were achieved for these C-CQDs based polymer solar cells, demonstrating that CQDs synthesized by CVD could be alternative to the fullerene derivatives for applying in polymer solar cells.

  2. Synthesis of an A-D-A type of molecule used as electron acceptor for improving charge transfer in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao-Zhi, E-mail: chzhzhang@sohu.com [Department of Chemistry, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Gu, Shu-Duo; Shen, Dan; Yuan, Yang [Department of Chemistry, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Zhang, Mingdao, E-mail: matchlessjimmy@163.com [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science & Technology, Nanjing 210044 (China)

    2016-08-22

    Electron-accepting molecules play an important role in developing organic solar cells. A new type of A-D-A molecule, 3,6-di([7-(5-bromothiophen-2-yl)-1,5,2,4,6,8-dithiotetrazocin-3-yl]thiophen -2-yl)-9-(2-ethylhexyl)carbazole, was synthesized. The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels are −3.55 and −5.85 eV, respectively. Therefore, the A-D-A type of compound could be used as electron acceptor for fabricating organic solar cell with a high open circuit voltage. Gibbs free energy (−49.2 kJ/mol) reveals that the process of A-D-A acceptor accepting an electron from poly(3-hexylthiophene) at excited state is spontaneous. The value of entropy (118 J/mol) in the process of an electron transferring from P3HT to the A-D-A acceptor at organic interface suggests that electrons generated from separation of electron-hole pairs at donor/acceptor interface would be delocalized efficiently. Therefore, the A-D-A molecule would be a potential acceptor for efficient organic BHJ solar cells.

  3. Electronic states of germanium grown under micro-gravity condition

    Energy Technology Data Exchange (ETDEWEB)

    Sugahara, A. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan)]. E-mail: sugahara@tsurugi.phys.sci.osaka-u.ac.jp; Ogawa, T. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Fujii, K. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Ohyama, T. [Liberal Arts, Fukui University of Technology, 3-6-1 Gakuen, Fukui, Fukui 910-8505 (Japan); Nakata, J. [Kyoto Semiconductor Corp. 418-9 Yodo Saime-cho, Fushimi-ku, Kyoto 613-0915 (Japan)

    2006-04-01

    Magneto-optical absorption measurements of Sb-doped germaniums grown under micro-gravity condition were carried out to investigate the influence of the gravity on crystal growth, using far-infrared laser and microwave. For comparison, we prepared two germanium crystals grown in the same conditions except the gravity conditions. In spite of the quite short growth period, the germanium grown under micro-gravity has a quite good quality. The lineshape analysis of Zeeman absorption peaks due to donor electrons indicates the existence of residual thermal acceptors.

  4. Development of a glucose sensor employing quick and easy modification method with mediator for altering electron acceptor preference.

    Science.gov (United States)

    Hatada, Mika; Loew, Noya; Inose-Takahashi, Yuka; Okuda-Shimazaki, Junko; Tsugawa, Wakako; Mulchandani, Ashok; Sode, Koji

    2018-02-09

    Enzyme based electrochemical biosensors are divided into three generations according to their type of electron transfer from the cofactors of the enzymes to the electrodes. Although the 3rd generation sensors using direct electron transfer (DET) type enzymes are ideal, the number of enzyme types which possess DET ability is limited. In this study, we report of a glucose sensor using mediator-modified glucose dehydrogenase (GDH), that was fabricated by a new quick-and-easy method using the pre-functionalized amine reactive phenazine ethosulfate (arPES). Thus mediator-modified GDH obtained the ability to transfer electrons to bulky electron acceptors as well as electrodes. The concentration of glucose was successfully measured using electrodes with immobilized PES-modified GDH, without addition of external electron mediators. Therefore, continuous monitoring systems can be developed based on this "2.5th generation" electron transfer principle utilizing quasi-DET. Furthermore, we successfully modified two other diagnostically relevant enzymes, glucoside 3-dehydrogenase and lactate oxidase, with PES. Therefore, various kinds of diagnostic enzymes can achieve quasi-DET ability simply by modification with arPES, suggesting that continuous monitoring systems based on the 2.5th generation principle can be developed for various target molecules. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Thiazole Imide-Based All-Acceptor Homopolymer: Achieving High-Performance Unipolar Electron Transport in Organic Thin-Film Transistors.

    Science.gov (United States)

    Shi, Yongqiang; Guo, Han; Qin, Minchao; Zhao, Jiuyang; Wang, Yuxi; Wang, Hang; Wang, Yulun; Facchetti, Antonio; Lu, Xinhui; Guo, Xugang

    2018-03-01

    High-performance unipolar n-type polymer semiconductors are critical for advancing the field of organic electronics, which relies on the design and synthesis of new electron-deficient building blocks with good solubilizing capability, favorable geometry, and optimized electrical properties. Herein, two novel imide-functionalized thiazoles, 5,5'-bithiazole-4,4'-dicarboxyimide (BTzI) and 2,2'-bithiazolothienyl-4,4',10,10'-tetracarboxydiimide (DTzTI), are successfully synthesized. Single crystal analysis and physicochemical study reveal that DTzTI is an excellent building block for constructing all-acceptor homopolymers, and the resulting polymer poly(2,2'-bithiazolothienyl-4,4',10,10'-tetracarboxydiimide) (PDTzTI) exhibits unipolar n-type transport with a remarkable electron mobility (μ e ) of 1.61 cm 2 V -1 s -1 , low off-currents (I off ) of 10 -10 -10 -11 A, and substantial current on/off ratios (I on /I off ) of 10 7 -10 8 in organic thin-film transistors. The all-acceptor homopolymer shows distinctive advantages over prevailing n-type donor-acceptor copolymers, which suffer from ambipolar transport with high I off s > 10 -8 A and small I on /I off s < 10 5 . The results demonstrate that the all-acceptor approach is superior to the donor-acceptor one, which results in unipolar electron transport with more ideal transistor performance characteristics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. A Twisted Thieno[3,4-b]thiophene-Based Electron Acceptor Featuring a 14-π-Electron Indenoindene Core for High-Performance Organic Photovoltaics.

    Science.gov (United States)

    Xu, Sheng Jie; Zhou, Zichun; Liu, Wuyue; Zhang, Zhongbo; Liu, Feng; Yan, Hongping; Zhu, Xiaozhang

    2017-11-01

    With an indenoindene core, a new thieno[3,4-b]thiophene-based small-molecule electron acceptor, 2,2'-((2Z,2'Z)-((6,6'-(5,5,10,10-tetrakis(2-ethylhexyl)-5,10-dihydroindeno[2,1-a]indene-2,7-diyl)bis(2-octylthieno[3,4-b]thiophene-6,4-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (NITI), is successfully designed and synthesized. Compared with 12-π-electron fluorene, a carbon-bridged biphenylene with an axial symmetry, indenoindene, a carbon-bridged E-stilbene with a centrosymmetry, shows elongated π-conjugation with 14 π-electrons and one more sp 3 carbon bridge, which may increase the tunability of electronic structure and film morphology. Despite its twisted molecular framework, NITI shows a low optical bandgap of 1.49 eV in thin film and a high molar extinction coefficient of 1.90 × 10 5 m -1 cm -1 in solution. By matching NITI with a large-bandgap polymer donor, an extraordinary power conversion efficiency of 12.74% is achieved, which is among the best performance so far reported for fullerene-free organic photovoltaics and is inspiring for the design of new electron acceptors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Anaerobic arsenite oxidation with an electrode serving as the sole electron acceptor: A novel approach to the bioremediation of arsenic-polluted groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Pous, Narcis [Laboratory of Chemical and Environmental Engineering (LEQUiA), Institute of the Environment, University of Girona, C/Maria Aurèlia Capmany, 69 E-17071 Girona (Spain); Casentini, Barbara; Rossetti, Simona; Fazi, Stefano [Water Research Institute (IRSA-CNR), National Research Council, Via Salaria Km 29.300, 00015 Monterotondo (Italy); Puig, Sebastià [Laboratory of Chemical and Environmental Engineering (LEQUiA), Institute of the Environment, University of Girona, C/Maria Aurèlia Capmany, 69 E-17071 Girona (Spain); Aulenta, Federico, E-mail: aulenta@irsa.cnr.it [Water Research Institute (IRSA-CNR), National Research Council, Via Salaria Km 29.300, 00015 Monterotondo (Italy)

    2015-02-11

    Highlights: • As(III) was oxidized to As(V) in a bioelectrochemical system. • A polarized graphite electrode served as electron acceptor. • Gammaproteobacteria were the dominating organisms at the electrode. - Abstract: Arsenic contamination of soil and groundwater is a serious problem worldwide. Here we show that anaerobic oxidation of As(III) to As(V), a form which is more extensively and stably adsorbed onto metal-oxides, can be achieved by using a polarized (+497 mV vs. SHE) graphite anode serving as terminal electron acceptor in the microbial metabolism. The characterization of the microbial populations at the electrode, by using in situ detection methods, revealed the predominance of gammaproteobacteria. In principle, the proposed bioelectrochemical oxidation process would make it possible to provide As(III)-oxidizing microorganisms with a virtually unlimited, low-cost and low-maintenance electron acceptor as well as with a physical support for microbial attachment.

  8. 2008 Electron Donor Acceptor Interactions Gordon Research Conference-August 3-8, 2009

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, Malcolm [Univ. of North Carolina, Chapel Hill, NC (United States); Gray, Nancy Ryan [Gordon Research Conferences, West Kingston, RI (United States)

    2009-09-19

    The conference presents and advances the current frontiers in experimental and theoretical studies of Electron Transfer and Transport in Molecular and Nano-scale Systems. The program includes sessions on coupled electron transfers, molecular solar energy conversion, biological and biomimetic systems, spin effects, ultrafast reactions and technical frontiers as well as electron transport in single molecules and devices.

  9. Interfacial electronic structure of Cl6SubPc non-fullerene acceptors in organic photovoltaics using soft X-ray spectroscopies.

    Science.gov (United States)

    Lee, Hyunbok; Ahn, Sun Woo; Ryu, Sim Hee; Ryu, Bo Kyung; Lee, Myeung Hee; Cho, Sang Wan; Smith, Kevin E; Jones, Tim S

    2017-12-06

    In organic photovoltaics (OPVs), determining the energy-level alignment of a donor and an acceptor is particularly important since the interfacial energy gap between the highest occupied molecular orbital (HOMO) level of a donor and the lowest unoccupied molecular orbital (LUMO) level of an acceptor (E-E) gives the theoretical maximum value of the open-circuit voltage (V OC ). To increase the E-E, non-fullerene acceptors, which have a lower electron affinity (EA) than C 60 , are receiving increasing attention. In this study, we investigated the energy-level alignment at the interface of a boron chloride subphthalocyanine (SubPc) donor and a halogenated SubPc (Cl 6 SubPc) acceptor using soft X-ray spectroscopy techniques. The estimated E-E of Cl 6 SubPc/SubPc was 1.95 eV, which was significantly higher than that of 1.51 eV found at the interface of C 60 /SubPc. This increased E-E was the origin of the enhanced V OC in OPVs. Additionally, we studied the molecular orientation of Cl 6 SubPc using angle-dependent X-ray absorption spectroscopy. The highly disordered Cl 6 SubPc molecules result in low carrier mobility, which contributes to the lower short-circuit current density of the Cl 6 SubPc acceptor OPVs than the C 60 acceptor OPVs.

  10. Beta transmutations in apatites with ferric iron as an electron acceptor - implication for nuclear waste form development.

    Science.gov (United States)

    Yao, Ge; Zhang, Zelong; Wang, Jianwei

    2017-09-27

    Apatite-structured materials have been considered for the immobilization of a number of fission products from reprocessing nuclear fuel because of their chemical durability as well as compositional and structural flexibility. It is hypothesized that the effect of beta decay on the stability can be mitigated by introducing an appropriate electron acceptor at the neighboring sites in the structure. The decay series 137 Cs → 137 Ba and 90 Sr → 90 Y → 90 Zr were investigated using a spin-polarized DFT approach to test the hypothesis. Apatites with compositions of Ca 10 (PO 4 ) 6 F 2 and Ca 4 Y 6 (SiO 4 ) 6 F 2 were selected as model systems for the incorporation of radionuclides Cs and Sr, respectively. Ferric iron was introduced in the structure as an electron acceptor. Electron density of states, crystal and defect structures, and energies before and after beta decay were calculated. The calculated electron density of states suggests that the extra electron is localized at the ferric iron, which changes its oxidation state and becomes ferrous iron. The crystal and defect structures were analyzed based on the volume, lattice parameters, radial distribution functions, metal cation to coordinating oxygen distances, and the metaprism twist angle of the apatite crystal structure. The results show that there are minor changes in the crystal and defect structures of CsFeCa 8 (PO 4 ) 6 F 2 with Cs + and Fe 3+ substitutions undergoing the Cs → Ba transmutation, and of Ca 3 SrY 4 Fe 2 (SiO 4 ) 6 F 2 with Sr 2+ and Fe 3+ substitutions undergoing the Sr → Y → Zr transmutations. The last decay change, from Y 3+ → Zr 4+ , causes relatively larger changes in the local defect structure around Zr involving the coordination environment but the change is not significant to the crystal structure. The results on calculated cohesive energy suggest that the transmutations Cs + → Ba 2+ and Sr 2+ → Y 3+ → Zr 4+ in both apatite compositions are energetically favorable

  11. Abundant Acceptor Emission from Nitrogen-Doped ZnO Films Prepared by Atomic Layer Deposition under Oxygen-Rich Conditions.

    Science.gov (United States)

    Guziewicz, E; Przezdziecka, E; Snigurenko, D; Jarosz, D; Witkowski, B S; Dluzewski, P; Paszkowicz, W

    2017-08-09

    Nitrogen-doped and undoped ZnO films were grown by thermal atomic layer deposition (ALD) under oxygen-rich conditions. Low-temperature photoluminescence spectra reveal a dominant donor-related emission at 3.36 eV and characteristic acceptor-related emissions at 3.302 and 3.318 eV. Annealing at 800 °C in oxygen atmosphere leads to conversion of conductivity from n- to p-type, which is reflected in photoluminescence spectra. Annealing does not increase any acceptor-related emission in the undoped sample, while in the ZnO:N it leads to a considerable enhancement of the photoluminescence at 3.302 eV. The high resolution cathodoluminescence cross-section images show different spatial distribution of the donor-related and the acceptor-related emissions, which complementarily contribute to the overall luminescence of the annealed ZnO:N material. Similar area of both emissions indicates that the acceptor luminescence comes neither from the grain boundaries nor from stacking faults. Moreover, in ZnO:N the acceptor-emission regions are located along the columns of growth, which shows a perspective to achieve a ZnO:N material with homogeneous acceptor conductivity at least at the micrometer scale.

  12. Substituent constant for drug design studies based on properties of organic electron donor--acceptor complexes.

    Science.gov (United States)

    Foster, R; Hyde, R M; Livingstone, D J

    1978-09-01

    A new model chemical system based on organic electron donor--aceptor complexes is described. From values of equilibrium constants measured by an NMR technique, a predictable parameter for use in quantitative structure--activity relationship techiques is discussed.

  13. ZnS and Graphene Quantum Dots Nanocomposite as Potential Electron Acceptor for Photovoltaics

    OpenAIRE

    S. M. Giripunje; Shikha Jindal

    2017-01-01

    Zinc sulphide (ZnS) quantum dots (QDs) were synthesized successfully via simple sonochemical method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) analysis revealed the average size of QDs of the order of 3.7 nm. The band gap of the QDs was tuned to 5.2 eV by optimizing the synthesis parameters. UV-Vis absorption spectra of ZnS QD confirm the quantum confinement effect. Fourier transform infrared (FTIR) analysis confir...

  14. Ultrafast static and diffusion-controlled electron transfer at Ag 29 nanocluster/molecular acceptor interfaces

    KAUST Repository

    Aly, Shawkat Mohammede

    2015-10-29

    Efficient absorption of visible light and a long-lived excited state lifetime of silver nanoclusters (Ag29 NCs) are integral properties for these new clusters to serve as light-harvesting materials. Upon optical excitation, electron injection at Ag29 NC/methyl viologen (MV2+) interfaces is very efficient and ultrafast. Interestingly, our femto- and nanosecond time-resolved results demonstrate clearly that both dynamic and static electron transfer mechanisms are involved in photoluminescence quenching of Ag29 NCs. © 2016 The Royal Society of Chemistry.

  15. Effect of additional electron acceptor in hybrid P3HT:PCBM:ZnO spin-coated films for photovoltaic application

    CSIR Research Space (South Africa)

    Muller, T

    2016-04-01

    Full Text Available methyl ester (PCBM) blend, and used as additional acceptors of electrons in the active layer. Metal–oxide interface layers between the active layer and ITO and the top contact layer, respectively, were introduced in the solar cell to compensate...

  16. Effects of Electron Acceptors, Reducing Agents, and Toxic Metabolites on Anaerobic Degradation of Heterocyclic Compounds

    DEFF Research Database (Denmark)

    Licht, Dorthe; Ahring, Birgitte Kiær; Arvin, Erik

    1996-01-01

    Degradation of four heterocyclic compounds was examined under nitrate-reducing, sulphate-reducing and methanogenic conditions. Soil samples from a creosote-polluted site in Denmark were used as inoculum. Indole and quinoline were degraded under all redox conditions with the highest degradation...

  17. Bias changing molecule–lead couple and inducing low bias negative differential resistance for electrons acceptor predicted by first-principles study

    International Nuclear Information System (INIS)

    Min, Y.; Fang, J.H.; Zhong, C.G.; Dong, Z.C.; Zhao, Z.Y.; Zhou, P.X.; Yao, K.L.

    2015-01-01

    A first-principles study of the transport properties of 3,13-dimercaptononacene–6,21-dione molecule sandwiched between two gold leads is reported. The strong effect of negative differential resistance with large peak-to-valley ratio of 710% is present under low bias. We found that bias can change molecule–lead couple and induce low bias negative differential resistance for electrons acceptor, which may promise the potential applications in molecular devices with low-power dissipation in the future. - Highlights: • Acceptor is constructed to negative differential resistor (NDR). • NDR effect is present under low bias. • Bias change molecule–lead couple and induce NDR effect

  18. N-Annulated perylene substituted zinc–porphyrins with different linking modes and electron acceptors for dye sensitized solar cells

    KAUST Repository

    Luo, Jie

    2016-05-03

    Three new N-annulated perylene (NP) substituted porphyrin dyes WW-7-WW-9 with different linking modes and accepting groups were synthesized and applied in Co(ii)/(iii) based dye sensitized solar cells (DSCs). The bay-linked porphyrins WW-7 and WW-8 exhibited moderate power conversion efficiency (PCE = 4.4% and 4.8%, respectively), while the peri-linked porphyrin dye WW-9 showed a PCE up to 9.2% which is slightly lower than that of our reference dye WW-6. Detailed physical measurements (optical and electrochemical), DFT calculations, and photovoltaic characterizations were performed to understand how the structural changes affect their light-harvesting ability, molecular orbital profile, energy level alignment, and eventually the photovoltaic performance. It turned out that the lower efficiencies of the cells based on WW-7 and WW-8 could be ascribed to the weak π-conjugation between the bay-substituted NP and phenylethynyl substituted porphyrin unit. The introduction of a benzothiadiazole acceptor at the anchoring group has induced a significant red shift of the IPCE action spectra of WW-8 and WW-9, by about 90 nm and 50 nm as compared to that of WW-7 and WW-6, respectively. However, less efficient electron injection was observed. Our studies gave some insight into the important role of electronic interactions between different components when one designs a dye for high-efficiency DSCs. © The Royal Society of Chemistry 2016.

  19. Transition Metal Donor-Peptide-Acceptor Complexes: From Intramolecular Electron Transfer Reactions to the Study of Reactive Intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Isied, Stephan S.

    2003-03-11

    The trans-polyproline (PII) oligomers (Figure 1) are unusually rigid peptide structures which have been extensively studied by our group for peptide mediated intramolecular electron transfer (ET) at long distances. We have previously studied ET across a series of metal ion donor (D) acceptor (A) oligoproline peptides with different distances, driving forces and reorganizational energies. The majority of these experiments involve generating the ET intermediate using pulse radiolysis methods, although more recently photochemical methods are also used. Results of these studies showed that ET across peptides can vary by more than twelve orders of magnitude. Using ruthenium bipyridine donors, ET reaction rate constants across several proline residues (n = 4 - 9) occurred in the millisecond (ms) to {micro}s timescale, thus limiting the proline peptide conformational motions to only minor changes (far smaller than the large changes that occur on the ms to sec timescale, such as trans to cis proline isomerization). The present report describes our large data base of experimental results for D-peptide-A complexes in terms of a model where the involvement of both superexchange and hopping (hole and electron) mechanisms account for the long range ET rate constants observed. Our data shows that the change from superexchange to hopping mechanisms occurs at different distances depending on the type of D and A and their interactions with the peptides. Our model is also consistent with generalized models for superexchange and hopping which have been put forward by a number of theoretical groups to account for long range ET phenomena.

  20. Influence of Proton Acceptors on the Proton-Coupled Electron Transfer Reaction Kinetics of a Ruthenium-Tyrosine Complex.

    Science.gov (United States)

    Lennox, J Christian; Dempsey, Jillian L

    2017-11-22

    A polypyridyl ruthenium complex with fluorinated bipyridine ligands and a covalently bound tyrosine moiety was synthesized, and its photo-induced proton-coupled electron transfer (PCET) reactivity in acetonitrile was investigated with transient absorption spectroscopy. Using flash-quench methodology with methyl viologen as an oxidative quencher, a Ru 3+ species is generated that is capable of initiating the intramolecular PCET oxidation of the tyrosine moiety. Using a series of substituted pyridine bases, the reaction kinetics were found to vary as a function of proton acceptor concentration and identity, with no significant H/D kinetic isotope effect. Through analysis of the kinetics traces and comparison to a control complex without the tyrosine moiety, PCET reactivity was found to proceed through an equilibrium electron transfer followed by proton transfer (ET-PT) pathway in which irreversible deprotonation of the tyrosine radical cation shifts the ET equilibrium, conferring a base dependence on the reaction. Comprehensive kinetics modeling allowed for deconvolution of complex kinetics and determination of rate constants for each elementary step. Across the five pyridine bases explored, spanning a range of 4.2 pK a units, a linear free-energy relationship was found for the proton transfer rate constant with a slope of 0.32. These findings highlight the influence that proton transfer driving force exerts on PCET reaction kinetics.

  1. 5' modification of duplex DNA with a ruthenium electron donor-acceptor pair using solid-phase DNA synthesis

    Science.gov (United States)

    Frank, Natia L.; Meade, Thomas J.

    2003-01-01

    Incorporation of metalated nucleosides into DNA through covalent modification is crucial to measurement of thermal electron-transfer rates and the dependence of these rates with structure, distance, and position. Here, we report the first synthesis of an electron donor-acceptor pair of 5' metallonucleosides and their subsequent incorporation into oligonucleotides using solid-phase DNA synthesis techniques. Large-scale syntheses of metal-containing oligonucleotides are achieved using 5' modified phosporamidites containing [Ru(acac)(2)(IMPy)](2+) (acac is acetylacetonato; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (3) and [Ru(bpy)(2)(IMPy)](2+) (bpy is 2,2'-bipyridine; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (4). Duplexes formed with the metal-containing oligonucleotides exhibit thermal stability comparable to the corresponding unmetalated duplexes (T(m) of modified duplex = 49 degrees C vs T(m) of unmodified duplex = 47 degrees C). Electrochemical (3, E(1/2) = -0.04 V vs NHE; 4, E(1/2) = 1.12 V vs NHE), absorption (3, lambda(max) = 568, 369 nm; 4, lambda(max) = 480 nm), and emission (4, lambda(max) = 720 nm, tau = 55 ns, Phi = 1.2 x 10(-)(4)) data for the ruthenium-modified nucleosides and oligonucleotides indicate that incorporation into an oligonucleotide does not perturb the electronic properties of the ruthenium complex or the DNA significantly. In addition, the absence of any change in the emission properties upon metalated duplex formation suggests that the [Ru(bpy)(2)(IMPy)](2+)[Ru(acac)(2)(IMPy)](2+) pair will provide a valuable probe for DNA-mediated electron-transfer studies.

  2. Charge transport studies in donor-acceptor block copolymer PDPP-TNT and PC71BM based inverted organic photovoltaic devices processed in room conditions

    Science.gov (United States)

    Srivastava, Shashi B.; Sonar, Prashant; Singh, Samarendra P.

    2015-07-01

    Diketopyrrolopyrole-naphthalene polymer (PDPP-TNT), a donor-acceptor co-polymer, has shown versatile behavior demonstrating high performances in organic field-effect transistors (OFETs) and organic photovoltaic (OPV) devices. In this paper we report investigation of charge carrier dynamics in PDPP-TNT, and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) bulk-heterojunction based inverted OPV devices using current density-voltage (J-V) characteristics, space charge limited current (SCLC) measurements, capacitance-voltage (C-V) characteristics, and impedance spectroscopy (IS). OPV devices in inverted architecture, ITO/ZnO/PDPP-TNT:PC71BM/MoO3/Ag, are processed and characterized at room conditions. The power conversion efficiency (PCE) of these devices are measured ˜3.8%, with reasonably good fill-factor 54.6%. The analysis of impedance spectra exhibits electron's mobility ˜2 × 10-3 cm2V-1s-1, and lifetime in the range of 0.03-0.23 ms. SCLC measurements give hole mobility of 1.12 × 10-5 cm2V-1s-1, and electron mobility of 8.7 × 10-4 cm2V-1s-1.

  3. Effects of electron acceptors on sulphate reduction activity in activated sludge processes

    NARCIS (Netherlands)

    Rubio-Rincón, Francisco; Lopez-Vazquez, Carlos; Welles, L.; van den Brand, Tessa; Abbas, B.A.; van Loosdrecht, Mark C.M.; Brdanovic, Damir

    2017-01-01

    The concentration of sulphate present in wastewater can vary from 10 to 500 mg SO4 2−/L. During anaerobic conditions, sulphate is reduced to sulphide by sulphate-reducing bacteria (SRB). Sulphide generation is undesired in wastewater treatment plants (WWTPs). Previous

  4. Photophysical properties of 1,8-naphthalic anhydride in aprotic solvents: An electron acceptor in excited state

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sujay; Biswas, Subhanip; Mondal, Mousumi; Basu, Samita, E-mail: samita.basu@saha.ac.in

    2014-01-15

    1,8-Naphthalic anhydride (NAN) has long been known as an intermediate for the synthesis of 1,8-naphthalimide derivatives with diverse applications. Uses of NAN for other purposes are restricted because it hydrolyzes in water and other protic solvents. In the current work we have investigated the absorption, steady-state and time-resolved fluorescence spectroscopy of NAN in eight different aprotic solvents of varying polarity. The compound is found to have different quantum yields in all the solvents. Astoundingly, NAN shows minimal fluorescence yield in dimethyl sulphoxide and N,N-dimethylformamide which is found to originate from pure collisional quenching owing to proton affinity of the solvent. In aprotic solvents acetonitrile and ethyl acetate, fluorescence emission and lifetime of NAN are quenched on addition of aliphatic amines namely triethylamine (TEA), tri-N-butylamine (TBA) and diisopropylethylamine (DIEA). Laser flash photolysis experiments in acetonitrile solvent have been used to find out the transient intermediates, which depict the involvement of photo-induced electron transfer from the amines to NAN. Hence, NAN has the potential to act as an efficient photo-induced electron acceptor in aprotic medium. -- Highlights: • In aprotic solvents NAN absorbs with maximum around 330–340 nm. • NAN fluoresce in aprotic solvents with maximum around 345–395 nm. • NAN has negligibly poor fluorescence in DMSO and DMF. • Fluorescence of NAN in aprotic solvents is quenched by TEA, TBA and DIEA. • Photo-induced electron transfer from the amines to NAN is the reason for such interaction.

  5. Substituted perylene diimides as electron acceptors in organic solar cells: Suppressing aggregate formation to increase device efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Kamm, Valentin; Battagliarin, Glauco; Howard, Ian A.; Hansen, Michael; Spiess, Hans W.; Mavrinskiy, Alexey; Pisula, Wojciech; Li, Chen; Muellen, Klaus; Laquai, Frederic [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany)

    2011-07-01

    Perylene diimide (PDI) is a promising electron acceptor material for high open circuit voltage bulk heterojunction organic solar cells. However, many PDI molecules have the drawback of strong aggregation leading to intermolecular excited state formation that results in exciton trapping. These traps can effectively limit the diffusion of excitons to the interface where charge separation occurs and thus strongly reduce the charge generation efficiency. In this contribution we study the influence of substitution of PDI molecules with side groups attached to the terminal and to the perylene core positions on the formation of aggregates. In particular transient photoluminescence and absorption spectroscopy are used to probe the impact of aggregation on the dynamics of charge generation and recombination in bulk heterojunction solar cells. Besides, AFM, x-ray and solid state NMR techniques are used to get further insight into the solid state morphology of polymer: PDI blends on different length scales. Finally, we correlate the photophysical properties of the PDI derivatives with the efficiency of bulk heterojunction organic solar cells and present unprecedented efficiencies from polymer: PDI solar cells.

  6. The use of intermediate electron acceptors to enhance MTT bioreduction in a microculture tetrazolium assay for human growth hormone.

    Science.gov (United States)

    Goodwin, C J; Holt, S J; Downes, S; Marshall, N J

    1996-01-01

    We contrast the effects of three intermediate electron acceptors (IEAs) on the highly quantitative ESTA bioassay for human growth hormone. This is a microculture tetrazolium assay based upon the in vitro reduction of the tetrazolium salt MTT, by Nb2 cells which have been activated with hGH. Each of the IEAs influenced MTT-formazan production in a distinctive manner. The two quinonoids, namely menadione and co-enzyme Q0 markedly increased the MTT-formazan produced by hormone activated Nb2 cells and thereby amplified the response of our bioassay for human growth hormone (hGH). The exceptionally low bioassay baseline which is characteristic of the unstimulated Nb2 cells when only MTT is added was retained in the presence of CoQ0, but was greatly increased by menadione. Phenazine methosulphate, which is the most widely used redox intermediary in microculture tetrazolium assays, also increased the baseline, but had only a minimal additional effect on MTT reduction by activated Nb2 cells. We conclude that CoQ0 is the preferred IEA for this ESTA bioassay for hGH.

  7. Assembly of coupled redox fuel cells using copper as electron acceptors to generate power and its in-situ retrieval.

    Science.gov (United States)

    Zhang, Hui-Min; Xu, Wei; Li, Gang; Liu, Zhan-Meng; Wu, Zu-Cheng; Li, Bo-Geng

    2016-02-15

    Energy extraction from waste has attracted much interest nowadays. Herein, a coupled redox fuel cell (CRFC) device using heavy metals, such as copper, as an electron acceptor is assembled to testify the recoveries of both electricity and the precious metal without energy consumption. In this study, a NaBH4-Cu(II) CRFC was employed as an example to retrieve copper from a dilute solution with self-electricity production. The properties of the CRFC have been characterized, and the open circuit voltage was 1.65 V with a maximum power density of 7.2 W m(-2) at an initial Cu(2+) concentration of 1,600 mg L(-1) in the catholyte. 99.9% of the 400 mg L(-1) copper was harvested after operation for 24 h, and the product formed on the cathode was identified as elemental copper. The CRFC demonstrated that useful chemicals were recovered and the electricity contained in the chemicals was produced in a self-powered retrieval process.

  8. Assembly of coupled redox fuel cells using copper as electron acceptors to generate power and its in-situ retrieval

    Science.gov (United States)

    Zhang, Hui-Min; Xu, Wei; Li, Gang; Liu, Zhan-Meng; Wu, Zu-Cheng; Li, Bo-Geng

    2016-02-01

    Energy extraction from waste has attracted much interest nowadays. Herein, a coupled redox fuel cell (CRFC) device using heavy metals, such as copper, as an electron acceptor is assembled to testify the recoveries of both electricity and the precious metal without energy consumption. In this study, a NaBH4-Cu(II) CRFC was employed as an example to retrieve copper from a dilute solution with self-electricity production. The properties of the CRFC have been characterized, and the open circuit voltage was 1.65 V with a maximum power density of 7.2 W m-2 at an initial Cu2+ concentration of 1,600 mg L-1 in the catholyte. 99.9% of the 400 mg L-1 copper was harvested after operation for 24 h, and the product formed on the cathode was identified as elemental copper. The CRFC demonstrated that useful chemicals were recovered and the electricity contained in the chemicals was produced in a self-powered retrieval process.

  9. Self-assembly properties of semiconducting donor-acceptor-donor bithienyl derivatives of tetrazine and thiadiazole-effect of the electron accepting central ring.

    Science.gov (United States)

    Zapala, Joanna; Knor, Marek; Jaroch, Tomasz; Maranda-Niedbala, Agnieszka; Kurach, Ewa; Kotwica, Kamil; Nowakowski, Robert; Djurado, David; Pecaut, Jacques; Zagorska, Malgorzata; Pron, Adam

    2013-11-26

    Scanning tunneling microscopy was used to study the effect of the electron-accepting unit and the alkyl substituent's position on the type and extent of 2D supramolecular organization of penta-ring donor-acceptor-donor (DAD) semiconductors, consisting of either tetrazine or thiadiazole central acceptor ring symmetrically attached to two bithienyl groups. Microscopic observations of monomolecular layers on HOPG of four alkyl derivatives of the studied adsorbates indicate significant differences in their 2D organizations. Ordered monolayers of thiadiazole derivatives are relatively loose and, independent of the position of alkyl substituents, characterized by large intermolecular separation of acceptor units in the adjacent molecules located in the face-to-face configuration. The 2D supramolecular architecture in both derivatives of thiadiazole is very sensitive to the alkyl substituent's position. Significantly different behavior is observed for derivatives of tetrazine (which is a stronger electron acceptor). Stronger intermolecular DA interactions in these adsorbates generate an intermolecular shift in the monolayer, which is a dominant factor determining the 2D structural organization. As a consequence of this molecular arrangement, tetrazine groups (A segments) face thiophene rings (D segments) of the neighboring molecules. Monolayers of tetrazine derivatives are therefore much more densely packed and characterized by similar π-stacking of molecules independently of the position of alkyl substituents. Moreover, a comparative study of 3D supramolecular organization, deduced from the X-ray diffraction patterns, is also presented clearly confirming the polymorphism of the studied adsorbates.

  10. Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules I. Reference Data at the CCSD(T) Complete Basis Set Limit

    KAUST Repository

    Richard, Ryan M.

    2016-01-05

    © 2016 American Chemical Society. In designing organic materials for electronics applications, particularly for organic photovoltaics (OPV), the ionization potential (IP) of the donor and the electron affinity (EA) of the acceptor play key roles. This makes OPV design an appealing application for computational chemistry since IPs and EAs are readily calculable from most electronic structure methods. Unfortunately reliable, high-accuracy wave function methods, such as coupled cluster theory with single, double, and perturbative triples [CCSD(T)] in the complete basis set (CBS) limit are too expensive for routine applications to this problem for any but the smallest of systems. One solution is to calibrate approximate, less computationally expensive methods against a database of high-accuracy IP/EA values; however, to our knowledge, no such database exists for systems related to OPV design. The present work is the first of a multipart study whose overarching goal is to determine which computational methods can be used to reliably compute IPs and EAs of electron acceptors. This part introduces a database of 24 known organic electron acceptors and provides high-accuracy vertical IP and EA values expected to be within ±0.03 eV of the true non-relativistic, vertical CCSD(T)/CBS limit. Convergence of IP and EA values toward the CBS limit is studied systematically for the Hartree-Fock, MP2 correlation, and beyond-MP2 coupled cluster contributions to the focal point estimates.

  11. Metal-tolerant thermophiles: metals as electron donors and acceptors, toxicity, tolerance and industrial applications.

    Science.gov (United States)

    Ranawat, Preeti; Rawat, Seema

    2018-02-01

    Metal-tolerant thermophiles are inhabitants of a wide range of extreme habitats like solfatara fields, hot springs, mud holes, hydrothermal vents oozing out from metal-rich ores, hypersaline pools and soil crusts enriched with metals and other elements. The ability to withstand adverse environmental conditions, like high temperature, high metal concentration and sometimes high pH in their niche, makes them an interesting subject for understanding mechanisms behind their ability to deal with multiple duress simultaneously. Metals are essential for biological systems, as they participate in biochemistries that cannot be achieved only by organic molecules. However, the excess concentration of metals can disrupt natural biogeochemical processes and can impose toxicity. Thermophiles counteract metal toxicity via their unique cell wall, metabolic factors and enzymes that carry out metal-based redox transformations, metal sequestration by metallothioneins and metallochaperones as well as metal efflux. Thermophilic metal resistance is heterogeneous at both genetic and physiology levels and may be chromosomally, plasmid or transposon encoded with one or more genes being involved. These effective response mechanisms either individually or synergistically make proliferation of thermophiles in metal-rich habitats possibly. This article presents the state of the art and future perspectives of responses of thermophiles to metals at genetic as well as physiological levels.

  12. Charge transport studies in donor-acceptor block copolymer PDPP-TNT and PC71BM based inverted organic photovoltaic devices processed in room conditions

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Shashi B.; Singh, Samarendra P., E-mail: samarendra.singh@snu.edu.in [Department of Physics, Shiv Nadar University, Gautam Buddha Nagar, Uttar Pradesh, India-201307 (India); Sonar, Prashant [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia-4001 (Australia)

    2015-07-15

    Diketopyrrolopyrole-naphthalene polymer (PDPP-TNT), a donor-acceptor co-polymer, has shown versatile behavior demonstrating high performances in organic field-effect transistors (OFETs) and organic photovoltaic (OPV) devices. In this paper we report investigation of charge carrier dynamics in PDPP-TNT, and [6,6]-phenyl C{sub 71} butyric acid methyl ester (PC71BM) bulk-heterojunction based inverted OPV devices using current density-voltage (J-V) characteristics, space charge limited current (SCLC) measurements, capacitance-voltage (C-V) characteristics, and impedance spectroscopy (IS). OPV devices in inverted architecture, ITO/ZnO/PDPP-TNT:PC71BM/MoO{sub 3}/Ag, are processed and characterized at room conditions. The power conversion efficiency (PCE) of these devices are measured ∼3.8%, with reasonably good fill-factor 54.6%. The analysis of impedance spectra exhibits electron’s mobility ∼2 × 10{sup −3} cm{sup 2}V{sup −1}s{sup −1}, and lifetime in the range of 0.03-0.23 ms. SCLC measurements give hole mobility of 1.12 × 10{sup −5} cm{sup 2}V{sup −1}s{sup −1}, and electron mobility of 8.7 × 10{sup −4} cm{sup 2}V{sup −1}s{sup −1}.

  13. Charge transport studies in donor-acceptor block copolymer PDPP-TNT and PC71BM based inverted organic photovoltaic devices processed in room conditions

    Directory of Open Access Journals (Sweden)

    Shashi B. Srivastava

    2015-07-01

    Full Text Available Diketopyrrolopyrole-naphthalene polymer (PDPP-TNT, a donor-acceptor co-polymer, has shown versatile behavior demonstrating high performances in organic field-effect transistors (OFETs and organic photovoltaic (OPV devices. In this paper we report investigation of charge carrier dynamics in PDPP-TNT, and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM bulk-heterojunction based inverted OPV devices using current density-voltage (J-V characteristics, space charge limited current (SCLC measurements, capacitance-voltage (C-V characteristics, and impedance spectroscopy (IS. OPV devices in inverted architecture, ITO/ZnO/PDPP-TNT:PC71BM/MoO3/Ag, are processed and characterized at room conditions. The power conversion efficiency (PCE of these devices are measured ∼3.8%, with reasonably good fill-factor 54.6%. The analysis of impedance spectra exhibits electron’s mobility ∼2 × 10−3 cm2V−1s−1, and lifetime in the range of 0.03-0.23 ms. SCLC measurements give hole mobility of 1.12 × 10−5 cm2V−1s−1, and electron mobility of 8.7 × 10−4 cm2V−1s−1.

  14. Donor-Acceptor Interaction Determines the Mechanism of Photoinduced Electron Injection from Graphene Quantum Dots into TiO2: π-Stacking Supersedes Covalent Bonding.

    Science.gov (United States)

    Long, Run; Casanova, David; Fang, Wei-Hai; Prezhdo, Oleg V

    2017-02-22

    Interfacial electron transfer (ET) constitutes the key step in conversion of solar energy into electricity and fuels. Required for fast and efficient charge separation, strong donor-acceptor interaction is typically achieved through covalent chemical bonding and leads to fast, adiabatic ET. Focusing on interfaces of pyrene, coronene, and a graphene quantum dot (GQD) with TiO 2 , we demonstrate the opposite situation: covalent bonding leads to weak coupling and nonadiabatic (NA) ET, while through-space π-electron interaction produces adiabatic ET. Using real-time time-dependent density functional theory combined with NA molecular dynamics, we simulate photoinduced ET into TiO 2 from flat and vertically placed molecules and GQD containing commonly used carboxylic acid linkers. Both arrangements can be achieved experimentally with GQDs and other two-dimensional materials, such as MoS 2 . The weak through-bond donor-acceptor coupling is attributed to the π-electron withdrawing properties of the carboxylic acid group. The calculated ET time scales are in excellent agreement with pump-probe optical experiments. The simulations show that the ET proceeds faster than energy relaxation. The electron couples to a broad spectrum of vibrational modes, ranging from 100 cm -1 large-scale motions to 1600 cm -1 C-C stretches. Compared to graphene/TiO 2 heterojunctions, the molecule/TiO 2 and GQD/TiO 2 systems exhibit energy gaps, allowing for longer-lived excited states and hot electron injection, facilitating charge separation and higher voltage. The reported state-of-the-art simulations generate a detailed time-domain, atomistic description of the interfacial charge and energy transfer and relaxation processes, and demonstrate that the fundamental principles leading to efficient charge separation in nanoscale materials depend strongly and often unexpectedly on the type of donor-acceptor interaction. Understanding these principles is critical to the development of highly

  15. Electron Conditioning of Technical Aluminium Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Le Pimpec, F

    2004-09-02

    The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values (= 1.3, value of many pure elements [1]), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.

  16. Synthesis and quantitative structure-activity relationship of hydrazones of N-amino-N'-hydroxyguanidine as electron acceptors for xanthine oxidase.

    Science.gov (United States)

    Prusis, Peteris; Dambrova, Maija; Andrianov, Victor; Rozhkov, Eugene; Semenikhina, Valentina; Piskunova, Irena; Ongwae, Enock; Lundstedt, Torbjörn; Kalvinsh, Ivars; Wikberg, Jarl E S

    2004-06-03

    A series of new N-hydroxyguanidines were synthesized and tested for electron acceptor activity on bovine milk xanthine oxidase using xanthine as reducing substrate. Manual inspection of the structure-activity data revealed that molecules containing nitro groups ("set A") show a different structure-activity relationship pattern compared to non-nitro compounds ("set B"). Accordingly separate QSAR models were built and validated for the two sets. Substantial differences were found in properties governing acceptor activity for the models, the only common property being sterical access to the imino nitrogen atom of the hydroxyguanidinimines. For set A molecules the presence of a nitro substituent at a certain distance range from the hydroxuguanidino group was most important. In addition, the presence of a nitro group in the ortho position interacting with NH(2) of the hydroxyguanidino group, and the mutual geometry of the phenyl ring, hydroxyguanidine, and imine groups was important for this set. By contrast, for set B molecules the acceptor activity was most influenced by the geometry of methoxy groups and the size and geometry of meta and para substituents of the phenyl ring.

  17. BIOTRANSFORMATION OF GASOLINE-CONTAMINATED GROUNDWATER UNDER MIXED ELECTRON-ACCEPTOR CONDITIONS

    Science.gov (United States)

    This project represents a cooperative effort between the University of Waterloo and the U.S. Environmental Protection Agency. This report summarizes research conducted using both laboratory batch microcosms and field-scale sheet-piling cells to evaluate whether bioremediation of...

  18. Electronic Structure, Donor and Acceptor Transitions, and Magnetism of 3d Impurities in In2O3 and ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Raebiger, H.; Lany, S,; Zunger, A.

    2009-01-01

    3d transition impurities in wide-gap oxides may function as donor/acceptor defects to modify carrier concentrations, and as magnetic elements to induce collective magnetism. Previous first-principles calculations have been crippled by the LDA error, where the occupation of the 3d-induced levels is incorrect due to spurious charge spilling into the misrepresented host conduction band, and have only considered magnetism and carrier doping separately. We employ a band-structure-corrected theory, and present simultaneously the chemical trends for electronic properties, carrier doping, and magnetism along the series of 3d{sup 1}-3d{sup 8} transition-metal impurities in the representative wide-gap oxide hosts In{sub 2}O{sub 3} and ZnO. We find that most 3d impurities in In{sub 2}O{sub 3} are amphoteric, whereas in ZnO, the early 3d's (Sc, Ti, and V) are shallow donors, and only the late 3d's (Co and Ni) have acceptor transitions. Long-range ferromagnetic interactions emerge due to partial filling of 3d resonances inside the conduction band and, in general, require electron doping from additional sources.

  19. Electronic structure, donor and acceptor transitions, and magnetism of 3d impurities in In2O3 and ZnO

    Science.gov (United States)

    Raebiger, Hannes; Lany, Stephan; Zunger, Alex

    2009-04-01

    3d transition impurities in wide-gap oxides may function as donor/acceptor defects to modify carrier concentrations, and as magnetic elements to induce collective magnetism. Previous first-principles calculations have been crippled by the LDA error, where the occupation of the 3d -induced levels is incorrect due to spurious charge spilling into the misrepresented host conduction band, and have only considered magnetism and carrier doping separately. We employ a band-structure-corrected theory, and present simultaneously the chemical trends for electronic properties, carrier doping, and magnetism along the series of 3d1-3d8 transition-metal impurities in the representative wide-gap oxide hosts In2O3 and ZnO. We find that most 3d impurities in In2O3 are amphoteric, whereas in ZnO, the early 3d ’s (Sc, Ti, and V) are shallow donors, and only the late 3d ’s (Co and Ni) have acceptor transitions. Long-range ferromagnetic interactions emerge due to partial filling of 3d resonances inside the conduction band and, in general, require electron doping from additional sources.

  20. Density functional study of the electronic structure of dye-functionalized fullerenes and their model donor-acceptor complexes containing P3HT

    Energy Technology Data Exchange (ETDEWEB)

    Baruah, Tunna; Garnica, Amanda; Paggen, Marina; Basurto, Luis; Zope, Rajendra R. [Department of Physics, The University of Texas at El Paso, El Paso, Texas 79958 (United States)

    2016-04-14

    We study the electronic structure of C{sub 60} fullerenes functionalized with a thiophene-diketo-pyrrolopyrrole-thiophene based chromophore using density functional theory combined with large polarized basis sets. As the attached chromophore has electron donor character, the functionalization of the fullerene leads to a donor-acceptor (DA) system. We examine in detail the effect of the linker and the addition site on the electronic structure of the functionalized fullerenes. We further study the electronic structure of these DA complexes with a focus on the charge transfer excitations. Finally, we examine the interface of the functionalized fullerenes with the widely used poly(3-hexylthiophene-2,5-diyl) (P3HT) donor. Our results show that all functionalized fullerenes with an exception of the C{sub 60}-pyrrolidine [6,6], where the pyrrolidine is attached at a [6,6] site, have larger electron affinities relative to the pristine C{sub 60} fullerene. We also estimate the quasi-particle gap, lowest charge transfer excitation energy, and the exciton binding energies of the functionalized fullerene-P3MT model systems. Results show that the exciton binding energies in these model complexes are slightly smaller compared to a similarly prepared phenyl-C{sub 61}-butyric acid methyl ester (PCBM)-P3MT complex.

  1. Origin of Enhanced Hole Injection in Organic Light-Emitting Diodes with an Electron-Acceptor Doping Layer: p-Type Doping or Interfacial Diffusion?

    Science.gov (United States)

    Zhang, Lei; Zu, Feng-Shuo; Deng, Ya-Li; Igbari, Femi; Wang, Zhao-Kui; Liao, Liang-Sheng

    2015-06-10

    The electrical doping nature of a strong electron acceptor, 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN), is investigated by doping it in a typical hole-transport material, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine (NPB). A better device performance of organic light-emitting diodes (OLEDs) was achieved by doping NPB with HATCN. The improved performance could, in principle, arise from a p-type doping effect in the codeposited thin films. However, physical characteristics evaluations including UV-vis absorption, Fourier transform infrared absorption, and X-ray photoelectron spectroscopy demonstrated that there was no obvious evidence of charge transfer in the NPB:HATCN composite. The performance improvement in NPB:HATCN-based OLEDs is mainly attributed to an interfacial modification effect owing to the diffusion of HATCN small molecules. The interfacial diffusion effect of the HATCN molecules was verified by the in situ ultraviolet photoelectron spectroscopy evaluations.

  2. Enhancement of photovoltaic efficiency of phosphor doped organic solar cell by energy and electron transfer from the phosphor to C60 acceptor

    Science.gov (United States)

    Yang, Dongfang; Li, Wenlian; Chu, Bei; Su, Zisheng; Wang, Junbo; Zhang, Guang; Zhang, Feng

    2011-11-01

    About 67% increase in power conversion efficiency (PCE) of copper phthalocyanine/C60 based organic solar cells was demonstrated by doping 4 wt % iridium(III)bis(3-(2-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-onato-N',C4)(acetyl acetonate) (IrC6) into C60 acceptor layer. The raised PCE was proved to result from the efficient photo absorption of IrC6 followed by the energy and electron transfer from IrC6 to C60 due to the matched energy level alignment between these two species. Besides, IrC6 could also increase the exciton dissociation efficiency at the active interface of the solar cells. The more detail improvement mechanisms were also discussed.

  3. On chirality transfer in electron donor-acceptor complexes. A prediction for the sulfinimine···BF3 system.

    Science.gov (United States)

    Rode, Joanna E; Dobrowolski, Jan Cz

    2012-01-01

    Stabilization energies of the electron donor-acceptor sulfinimine···BF(3) complexes calculated at either the B3LYP/aug-cc-pVTZ or the MP2/aug-cc-pVTZ level do not allow to judge, whether the N- or O-atom in sulfinimine is stronger electron-donor to BF(3) . The problem seems to be solvable because chirality transfer phenomenon between chiral sulfinimine and achiral BF(3) is expected to be vibrational circular dichroism (VCD) active. Moreover, the bands associated with the achiral BF(3) molecule are predicted to be the most intense in the entire spectrum. However, the VCD band robustness analyses show that most of the chirality transfer modes of BF(3) are unreliable. Conversely, variation of VCD intensity with change of intermolecular distance, angle, and selected dihedrals between the complex partners shows that to establish the robustness of chirality transfer mode. It is also necessary to determine the influence of the potential energy surface (PES) shape on the VCD intensity. At the moment, there is still no universal criterion for the chirality transfer mode robustness and the conclusions formulated based on one system cannot be directly transferred even to a quite similar one. However, it is certain that more attention should be focused on relation of PES shape and the VCD mode robustness problem. Copyright © 2011 Wiley Periodicals, Inc.

  4. Biodegradation of pharmaceuticals and endocrine disruptors with oxygen, nitrate, manganese (IV), iron (III) and sulfate as electron acceptors

    Science.gov (United States)

    Schmidt, Natalie; Page, Declan; Tiehm, Andreas

    2017-08-01

    Biodegradation of pharmaceuticals and endocrine disrupting compounds was examined in long term batch experiments for a period of two and a half years to obtain more insight into the effects of redox conditions. A mix including lipid lowering agents (e.g. clofibric acid, gemfibrozil), analgesics (e.g. diclofenac, naproxen), beta blockers (e.g. atenolol, propranolol), X-ray contrast media (e.g. diatrizoic acid, iomeprol) as well as the antiepileptic carbamazepine and endocrine disruptors (e.g. bisphenol A, 17α-ethinylestradiol) was analyzed in batch tests in the presence of oxygen, nitrate, manganese (IV), iron (III), and sulfate. Out of the 23 selected substances, 14 showed a degradation of > 50% of their initial concentrations under aerobic conditions. The beta blockers propranolol and atenolol and the analgesics pentoxifylline and naproxen showed a removal of > 50% under anaerobic conditions. In particular naproxen proved to be degradable with oxygen and under most anaerobic conditions, i.e. with manganese (IV), iron (III), or sulfate. The natural estrogens estriol, estrone and 17β-estradiol showed complete biodegradation under aerobic and nitrate-reducing conditions, with a temporary increase of estrone during transformation of estriol and 17β-estradiol. Transformation of 17β-estradiol under Fe(III)-reducing conditions resulted in an increase of estriol as well. Concentrations of clofibric acid, carbamazepine, iopamidol and diatrizoic acid, known for their recalcitrance in the environment, remained unchanged.

  5. Determination of thermodynamic affinities of various polar olefins as hydride, hydrogen atom, and electron acceptors in acetonitrile.

    Science.gov (United States)

    Cao, Ying; Zhang, Song-Chen; Zhang, Min; Shen, Guang-Bin; Zhu, Xiao-Qing

    2013-07-19

    A series of 69 polar olefins with various typical structures (X) were synthesized and the thermodynamic affinities (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the polar olefins obtaining hydride anions, hydrogen atoms, and electrons, the thermodynamic affinities of the radical anions of the polar olefins (X(•-)) obtaining protons and hydrogen atoms, and the thermodynamic affinities of the hydrogen adducts of the polar olefins (XH(•)) obtaining electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The pure C═C π-bond heterolytic and homolytic dissociation energies of the polar olefins (X) in acetonitrile and the pure C═C π-bond homolytic dissociation energies of the radical anions of the polar olefins (X(•-)) in acetonitrile were estimated. The remote substituent effects on the six thermodynamic affinities of the polar olefins and their related reaction intermediates were examined using the Hammett linear free-energy relationships; the results show that the Hammett linear free-energy relationships all hold in the six chemical and electrochemical processes. The information disclosed in this work could not only supply a gap of the chemical thermodynamics of olefins as one class of very important organic unsaturated compounds but also strongly promote the fast development of the chemistry and applications of olefins.

  6. Electron and excitation energy transfers in covalently linked donor-acceptor dyads: mechanisms and dynamics revealed using quantum chemistry.

    Science.gov (United States)

    Cupellini, Lorenzo; Giannini, Samuele; Mennucci, Benedetta

    2017-12-20

    Photoinduced electron transfer (ET), hole transfer (HT), charge recombination (CR) and energy transfer (EET) are fundamental mechanisms, which occur in both natural and artificial light harvesting systems. Here, we present a computational strategy which determines ET, HT, CR and EET rates in a consistent way and merges them in a kinetic model to reproduce the net excited state dynamics. The effects of the solvent are included in all steps of the calculations making the present strategy a useful tool for a rational design of charge and energy transfer processes in complex systems. An application to covalently linked zinc and free-base porphyrin-naphthalenediimide dyads is presented. For each of the two systems, ultrafast optical spectroscopy experiments have shown a specific photophysics with different processes taking place simultaneously. The model reveals that such a diversity is mainly due to the different relative stability of the charge-separated state, while the electronic couplings for charge and energy transfer processes are quite similar in the two dyads.

  7. Chemical toxicology of reactive species in the atmosphere: two decades of progress in an electron acceptor and an electrophile.

    Science.gov (United States)

    Kumagai, Yoshito; Abiko, Yumi; Cong, Nho Luong

    2016-01-01

    Air pollutants such as diesel exhaust particles (DEP) are thought to cause pulmonary diseases such as asthma as a result of oxidative stress. While DEP contain a large number of polycyclic aromatic hydrocarbons, we have focused on 9,10-phenanthrenequinone (9,10-PQ) and 1,2-naphthoquinone (1,2-NQ) because of their chemical properties based on their oxidative and chemical modification capabilities. We have found that 9,10-PQ interacts with electron donors such as NADPH (in the presence of enzymes) and dithiols, resulting in generation of excess reactive oxygen species (ROS) through redox cycling. We have also shown that 1,2-NQ is able to modify protein thiols, leading to protein adducts associated with activation of redox signal transduction pathways at lower concentrations and toxicity at higher concentrations. In this review, we briefly introduce our findings from the last two decades.

  8. The nature of electron acceptor (MnIV/NO3) triggers differential expression of genes associated with stress and ammonium limitation responses in Shewanella algae C6G3.

    Science.gov (United States)

    Aigle, Axel; Bonin, Patricia; -Nunez, Nicolas Fernandez; Loriod, Béatrice; Guasco, Sophie; Bergon, Aurélie; Armougom, Fabrice; Iobbi-Nivol, Chantal; Imbert, Jean; Michotey, Valérie

    2018-03-16

    Shewanella algae C6G3 can reduce dissimilatively nitrate into ammonium and manganese-oxide (MnIV) into MnII. It has the unusual ability to produce anaerobically nitrite from ammonium in the presence of MnIV. To gain insight into their metabolic capabilities, global mRNA expression patterns were investigated by RNA-seq and qRT-PCR in cells growing with lactate and ammonium as carbon and nitrogen sources and with either MnIV or nitrate as electron acceptors. Gene exhibiting higher expression levels in the presence of MnIV belonged to functional categories of carbohydrate, coenzyme, lipid metabolisms and inorganic ion transport. Comparative transcriptomic pattern between MnIV and NO3 revealed that the strain presented an ammonium limitation status with MnIV, despite the presence of non-limiting concentration of ammonium under both culture conditions. In addition, in presence of MnIV, ntrB/nrtC regulators, ammonium channel, nitrogen regulatory protein P-II, glutamine synthetase and asparagine synthetase glutamine dependent genes were over-represented. Under nitrate condition, the expression of genes involved in the synthesis of several amino acids was increased. Finally, expression level of genes associated with the general stress response was also amplified and among them, katE, a putative catalase/peroxidase present on several Shewanella genomes, was highly expressed with a relative median value higher in MnIV condition.

  9. Associative Memory Acceptors.

    Science.gov (United States)

    Card, Roger

    The properties of an associative memory are examined in this paper from the viewpoint of automata theory. A device called an associative memory acceptor is studied under real-time operation. The family "L" of languages accepted by real-time associative memory acceptors is shown to properly contain the family of languages accepted by one-tape,…

  10. CdTe Nanocrystal Hetero-Junction Solar Cells with High Open Circuit Voltage Based on Sb-doped TiO₂ Electron Acceptor Materials.

    Science.gov (United States)

    Li, Miaozi; Liu, Xinyan; Wen, Shiya; Liu, Songwei; Heng, Jingxuan; Qin, Donghuan; Hou, Lintao; Wu, Hongbin; Xu, Wei; Huang, Wenbo

    2017-05-03

    We propose Sb-doped TiO₂ as electron acceptor material for depleted CdTe nanocrystal (NC) hetero-junction solar cells. Novel devices with the architecture of FTO/ZnO/Sb:TiO₂/CdTe/Au based on CdTe NC and TiO₂ precursor are fabricated by rational ambient solution process. By introducing TiO₂ with dopant concentration, we are able to tailor the optoelectronic properties of NC solar cells. Our novel devices demonstrate a very high open circuit voltage of 0.74 V, which is the highest V oc reported for any CdTe NC based solar cells. The power conversion efficiency (PCE) of solar cells increases with the increase of Sb-doped content from 1% to 3%, then decreases almost linearly with further increase of Sb content due to the recombination effect. The champion device shows J sc , V oc , FF, and PCE of 14.65 mA/cm², 0.70 V, 34.44, and 3.53% respectively, which is prospective for solution processed NC solar cells with high V oc .

  11. Bioremediation of PAHs contaminated river sediment by an integrated approach with sequential injection of co-substrate and electron acceptor: Lab-scale study.

    Science.gov (United States)

    Liu, Tongzhou; Zhang, Zhen; Dong, Wenyi; Wu, Xiaojing; Wang, Hongjie

    2017-11-01

    In this study, the feasibility of employing an integrated bioremediation approach in contaminated river sediment was evaluated. Sequential addition of co-substrate (acetate) and electron acceptor (NO 3 - ) in a two-phase treatment was capable of effectively removing polycyclic aromatic hydrocarbons (PAHs) in river sediment. The residual concentration of total PAHs decreased to far below effect range low (ERL) value within 91 days of incubation, at which concentration it could rarely pose biological impairment. The biodegradation of high molecular weight PAHs were found to be mainly occurred in the sediment treated with co-substrates (i.e. acetate or methanol), in which acetate was found to be more suitable for PAHs degradation. The role of co-substrates in influencing PAHs biodegradation was tentatively discussed herein. Additionally, the sediment odorous problem and blackish appearance were intensively addressed by NO 3 - injection. The results of this study demonstrated that integrating two or more approaches/processes would be a helpful option in sediment remediation. It can lead to a more effective remediation performance, handle multiple contamination issues, as well as mitigate environmental risks caused by one of the single methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Copolymer semiconductors comprising thiazolothiazole or benzobisthiazole, or benzobisoxazole electron acceptor subunits, and electron donor subunits, and their uses in transistors and solar cells

    Science.gov (United States)

    Jenekhe, Samson A; Subramaniyan, Selvam; Ahmed, Eilaf; Xin, Hao; Kim, Felix Sunjoo

    2014-10-28

    The inventions disclosed, described, and/or claimed herein relate to copolymers comprising copolymers comprising electron accepting A subunits that comprise thiazolothiazole, benzobisthiazole, or benzobisoxazoles rings, and electron donating subunits that comprise certain heterocyclic groups. The copolymers are useful for manufacturing organic electronic devices, including transistors and solar cells. The invention also relates to certain synthetic precursors of the copolymers. Methods for making the copolymers and the derivative electronic devices are also described.

  13. An electronic spectroscopic study of micellisation of surfactants and solvation of homomicelles formed by cationic or anionic surfactants using a solvatochromic electron donor acceptor dye.

    Science.gov (United States)

    Kedia, Niraja; Sarkar, Amrita; Purkayastha, Pradipta; Bagchi, Sanjib

    2014-10-15

    Solvatochromic absorption and fluorescence bands of a donor-acceptor dye have been utilised for following the micellisation and for probing the polarity of the aqueous homomicellar phase provided separately by cationic (cetyltrimethylammonimum bromide, CTAB and dodecyltrimethylammonimum bromide, DTAB) and anionic (sodium dodecyl sulphate, SDS) surfactant. Results indicate that for a low concentration of surfactant (below cmc) the dye forms a dimer in aqueous solution. In a micellar media, however, the dye exists as monomers. A strong dye-micelle interaction, as indicated by the shift of the solvatochromic intramolecular charge transfer band of the dye, has also been indicated. The absorption and fluorescence parameters of the dye have been utilised for studying the onset of aggregation of the surfactants. An iterative procedure has been developed for the estimation of cmc and the distribution coefficient (KD) of the dye between the aqueous and the micellar phase. All the parameters provide convergent values of cmc. A high value of KD indicates that the dye exists predominantly in the micellar phase. The solvatochromic parameters characterising the dipolarity-polarisability (π(*)) and H-bond donation ability (α) of modes of solvation interaction in different micellar media have been estimated. The dye is found to distribute itself between two regions in a catanionic vesicle formed by surfactants SDS and DTAB, one being relatively polar than other. The distribution coefficients have been found out using the fluorescence data. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. The strontium inorganic mutant of the water oxidizing center (CaMn4O5) of PSII improves WOC efficiency but slows electron flux through the terminal acceptors.

    Science.gov (United States)

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

    2016-09-01

    Herein we extend prior studies of biosynthetic strontium replacement of calcium in PSII-WOC core particles to characterize whole cells. Previous studies of Thermosynechococcus elongatus found a lower rate of light-saturated O2 from isolated PSII-WOC(Sr) cores and 5-8× slower rate of oxygen release. We find similar properties in whole cells, and show it is due to a 20% larger Arrhenius activation barrier for O2 evolution. Cellular adaptation to the sluggish PSII-WOC(Sr) cycle occurs in which flux through the QAQB acceptor gate becomes limiting for turnover rate in vivo. Benzoquinone derivatives that bind to QB site remove this kinetic chokepoint yielding 31% greater O2 quantum yield (QY) of PSII-WOC(Sr) vs. PSII-WOC(Ca). QY and efficiency of the WOC(Sr) catalytic cycle are greatly improved at low light flux, due to fewer misses and backward transitions and 3-fold longer lifetime of the unstable S3 state, attributed to greater thermodynamic stabilization of the WOC(Sr) relative to the photoactive tyrosine YZ. More linear and less cyclic electron flow through PSII occurs per PSII-WOC(Sr). The organismal response to the more active PSII centers in Sr-grown cells at 45°C is to lower the number of active PSII-WOC per Chl, producing comparable oxygen and energy per cell. We conclude that redox and protonic energy fluxes created by PSII are primary determinants for optimal growth rate of T. elongatus. We further conclude that the (Sr-favored) intermediate-spin S=5/2 form of the S2 state is the active form in the catalytic cycle relative to the low-spin S=1/2 form. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Synthesis, characterization of bay-substituted perylene diimide based D-A-D type small molecules and their applications as a non-fullerene electron acceptor in polymer solar cells

    Directory of Open Access Journals (Sweden)

    Ramasamy Ganesamoorthy

    2018-03-01

    Full Text Available We report a series of bay substituted perylene diimide based donor-acceptor-donor (D-A-D type small molecule acceptor derivatives such as S-I, S-II, S-III and S-IV for small molecule based organic solar cell (SM-OSC applications. The electron rich thiophene derivatives such as thiophene, 2-hexylthiophene, 2,2′-bithiophene, and 5-hexyl-2,2′-bithiophene were used as a donor (D, and perylene diimide was used as an acceptor (A. The synthesized small molecules were confirmed by FT-IR, NMR, and HR-MS. The small molecules showed wide and strong absorption in the UV-vis region up to 750 nm, which reduced the optical band gap to <2 eV. The calculated highest occupied molecular orbital (HOMO and the lowest unoccupied molecular orbital (LUMO were comparable with those of the PC61BM. Scanning electron microscope (SEM studies confirmed the aggregation of the small molecules, S-I to S-IV. Small molecules showed thermal stability up to 300 °C. In bulk heterojunction organic solar cells (BHJ-OSCs, the S-I based device showed a maximum power conversion efficiency (PCE of 0.12% with P3HT polymer donor. The PCE was declined with respect to the number of thiophene units and the flexible alkyl chain in the bay position. Keywords: Perylene diimide, Donor–acceptor, Small molecule, Non-fullerene, Suzuki coupling

  16. The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

    Directory of Open Access Journals (Sweden)

    Aurica Farcas

    2014-09-01

    Full Text Available We report on the synthesis as well as the optical, electrochemical and morphological properties of two polyrotaxanes (4a and 4b, which consist of electron-accepting 9,9-dicyanomethylenefluorene 1 as an inclusion complex in persilylated β- or γ-cyclodextrin (TMS-β-CD, TMS-γ-CD (1a, 1b and methyltriphenylamine as an electron-donating molecule. They are statistically distributed into the conjugated chains of 9,9-dioctylfluorene 3 and compared with those of the corresponding non-rotaxane 4 counterpart. Rotaxane formation results in improvements of the solubility, the thermal stability, and the photophysical properties. Polyrotaxanes 4a and 4b exhibited slightly red-shifted absorption bands with respect to the non-rotaxane 4 counterpart. The fluorescence lifetimes of polyrotaxanes follow a mono-exponential decay with a value of τ = 1.14 ns compared with the non-rotaxane, where a bi-exponential decay composed of a main component with a relative short time of τ1 = 0.88 (57.08% and a minor component with a longer lifetime of τ2 = 1.56 ns (42.92% were determined. The optical and electrochemical band gaps (ΔEg as well as the ionization potential and electronic affinity characterized by smaller values compared to the values of any of the constituents. AFM reveals that the film surface of 4a and 4b displays a granular morphology with a lower dispersity supported by a smaller roughness exponent compared with the non-rotaxane counterpart.

  17. The role of amino acid electron-donor/acceptor atoms in host-cell binding peptides is associated with their 3D structure and HLA-binding capacity in sterile malarial immunity induction

    Energy Technology Data Exchange (ETDEWEB)

    Patarroyo, Manuel E., E-mail: mepatarr@mail.com [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia); Universidad Nacional de Colombia, Bogota (Colombia); Almonacid, Hannia; Moreno-Vranich, Armando [Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota (Colombia)

    2012-01-20

    Highlights: Black-Right-Pointing-Pointer Fundamental residues located in some HABPs are associated with their 3D structure. Black-Right-Pointing-Pointer Electron-donor atoms present in {beta}-turn, random, distorted {alpha}-helix structures. Black-Right-Pointing-Pointer Electron-donor atoms bound to HLA-DR53. Black-Right-Pointing-Pointer Electron-acceptor atoms present in regular {alpha}-helix structure bound to HLA-DR52. -- Abstract: Plasmodium falciparum malaria continues being one of the parasitic diseases causing the highest worldwide mortality due to the parasite's multiple evasion mechanisms, such as immunological silence. Membrane and organelle proteins are used during invasion for interactions mediated by high binding ability peptides (HABPs); these have amino acids which establish hydrogen bonds between them in some of their critical binding residues. Immunisation assays in the Aotus model using HABPs whose critical residues had been modified have revealed a conformational change thereby enabling a protection-inducing response. This has improved fitting within HLA-DR{beta}1{sup Asterisk-Operator} molecules where amino acid electron-donor atoms present in {beta}-turn, random or distorted {alpha}-helix structures preferentially bound to HLA-DR53 molecules, whilst HABPs having amino acid electron-acceptor atoms present in regular {alpha}-helix structure bound to HLA-DR52. This data has great implications for vaccine development.

  18. Effects of inorganic electron acceptors on methanogenesis and methanotrophy and on the community structure of bacteria and archaea in sediments of a boreal lake

    Science.gov (United States)

    Rissanen, Antti J.; Karvinen, Anu; Nykänen, Hannu; Peura, Sari; Tiirola, Marja; Mäki, Anita; Kankaala, Paula

    2016-04-01

    Lake sediments are globally significant sources of CH4 to the atmosphere, but the factors controlling the production and consumption of CH4 in these systems are understudied. Increasing availability of electron acceptors (EA) (other than CO2) in sediments can decrease or even suppress CH4 production by diverting the electron flow (from H2 and organic substances) from methanogenic to other anaerobic respiration pathways. However, whether these changes in microbial function extend down to changes in the structure of microbial communities is not known. Also anaerobic oxidation of methane (AOM) could be enhanced by increased availability of EAs (SO42-, NO3-, Fe3+ and Mn4+), but information on the role of this process in lake sediments is scarce. We studied the effects of inorganic EAs on the potential for CH4 production and consumption and on the structure of microbial communities in sediments of a boreal lake. Anoxic slurries of sediment samples collected from two depths (0 - 10 cm; 10 - 30 cm) of the profundal zone of a boreal, mesotrophic Lake Ätäskö, were amended with 1) CH4 or with CH4 and either 2) 10 mM Mn4+, 3) 10 mM Fe3+, 4) O2 or 5) CH2F2 (inhibitor of aerobic methane oxidation) and incubated at +10° C for up to 4 months. Furthermore, slurries from the 10 - 30 cm layer were amended with CH4 and either 6) 2 mM NO3- or 7) 2 mM SO42- and incubated at +4 ° C for up to 14 months. The processes were measured using 13C-labelling and by concentration measurements of CH4 and CO2. Effects of treatments 1-3 on microbial communities were also analysed by next-generation sequencing of 16S rRNA, as well as methyl coenzyme-M reductase gene amplicons and mRNA transcripts. CH4 production (max. 83 nmol gdw-1d-1) took place in the anaerobic treatments but was generally decreased by the addition of NO3-, SO42-, Fe3+ and Mn4+. Although the structure of sediment archaeal community was resistant to Fe3+/Mn4+ - additions, slight changes in the structure of bacterial community

  19. Syntheses of donor-acceptor-functionalized dihydroazulenes

    DEFF Research Database (Denmark)

    Broman, Søren Lindbæk; Jevric, Martyn; Bond, Andrew

    2014-01-01

    The dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch has been of interest for use in molecular electronics and advanced materials. The switching between the two isomers has previously been found to depend strongly on the presence of donor and acceptor groups. The fine-tuning of opt...

  20. Modeling charge transfer at organic donor-acceptor semiconductor interfaces

    NARCIS (Netherlands)

    Cakir, Deniz; Bokdam, Menno; de Jong, Machiel Pieter; Fahlman, M.; Brocks, G.

    2012-01-01

    We develop an integer charge transfer model for the potential steps observed at interfaces between donor and acceptor molecular semiconductors. The potential step can be expressed as the difference between the Fermi energy pinning levels of electrons on the acceptor material and holes on the donor

  1. Photochemical stability of conjugated polymers, electron acceptors and blends for polymer solar cells resolved in terms of film thickness and absorbance

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Vesterager Madsen, Morten; Carlé, Jon Eggert

    2012-01-01

    and absorbance. A fully automated degradation setup allowed for inclusion of in excess of 1000 degradations in this study to enable a discussion of reliability of the technique. Degradation rates were found to increase exponentially with decreasing film absorbance for all materials. The relative stabilities...... acceptors poses a challenge to solar cell encapsulation if these materials are to be of commercial interest. The presented method is generally applicable to all types of organic materials to assess photochemical stabilities. The presented results of conjugated polymers demonstrate that this is a powerful...

  2. Thermalization of secondary electrons under AMSGEMP conditions

    International Nuclear Information System (INIS)

    Bloomberg, H.W.; Pine, V.W.

    1984-01-01

    A Monte Carlo algorithm is used to determine the time behavior of source secondary electrons for ranges of the electric field to pressure ratio E/p of interest in AMSGEMP. The algorithm contains a very detailed cross section set describing electron interactions with the background gas. The authors show that the delay in the attainment of the peak time independent ionization frequency (or ionization coefficient) may result in negligible ionization over times of interest. In any case the behavior is shown to behave much differently than in examples where limited cross section sets, common in currently employed predictive codes, are employed. In particular, the importance of momentum transfer is indicated. A critique of the scaling implications of the phenomena is made

  3. Abooming area:non-fullerene acceptors for organic solar cells

    Directory of Open Access Journals (Sweden)

    QU Yangkun

    2016-12-01

    Full Text Available Organic solar cells have been extensively investigated in the last decade because they are one of the very important solutions to the global energy crisis.While predominant electron acceptor materials for organic solar cell are focused on fullerene and its derivatives,scientists are now more desperately looking for new alternative acceptor materials because fullerene acceptors face the challenges of narrow absorption spectrum,low solubility,high cost and non-environmental friendly synthesis processes.Non-fullerene electron acceptors have drawn great attention recently and have been widely used in organic solar cells because they have the great advantages of wide absorption spectrum,high solubility,precise structural controllability,and good processability.In this review paper,we summarize the most significant progresses in the area of non-fullerene organic solar cell acceptors during the last 6 years and we look forward to a bright future of non-fullerene organic solar cells.

  4. Electron Conditioning of Technical Aluminium Surfaces: Effect on the Secondary Electron Yield

    Energy Technology Data Exchange (ETDEWEB)

    Le Pimpec, F.

    2004-12-13

    The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values (< 1.3, value of many pure elements [1] ), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.

  5. Theory of Primary Photoexcitations in Donor-Acceptor Copolymers

    OpenAIRE

    Aryanpour, Karan; Dutta, Tirthankar; Huynh, Uyen N. V.; Vardeny, Zeev Valy; Mazumdar, Sumit

    2015-01-01

    We present a generic theory of primary photoexcitations in low band gap donor-acceptor conjugated copolymers. Because of the combined effects of strong electron correlations and broken symmetry, there is considerable mixing between a charge-transfer exciton and an energetically proximate triplet-triplet state with an overall spin singlet. The triplet-triplet state, optically forbidden in homopolymers, is allowed in donor-acceptor copolymers. For an intermediate difference in electron affiniti...

  6. Humidity Buildup in Electronic Enclosures Exposed to Constant Conditions

    DEFF Research Database (Denmark)

    Conseil, Helene; Staliulionis, Zygimantas; Jellesen, Morten Stendahl

    2017-01-01

    Electronic components and devices are exposed to a wide variety of climatic conditions, therefore the protection of electronic devices from humidity is becoming a critical factor in the system design. The ingress of moisture into typical electronic enclosures has been studied with defined paramet....... The moisture buildup inside the enclosure has been simulated using an equivalent RC circuit consisting of variables like controlled resistors and capacitors to describe the diffusivity, permeability, and storage in polymers....

  7. Intramolecular charge separation in spirobifluorene-based donor–acceptor compounds adsorbed on Au and indium tin oxide electrodes

    International Nuclear Information System (INIS)

    Heredia, Daniel; Otero, Luis; Gervaldo, Miguel; Fungo, Fernando; Dittrich, Thomas; Lin, Chih-Yen; Chi, Liang-Chen; Fang, Fu-Chuan; Wong, Ken-Tsung

    2013-01-01

    Surface photovoltage (SPV) measurements were performed with a Kelvin-probe in spirobifluorene-based donor (diphenylamine)–acceptor (dicyano or cyanoacrylic acid moieties) compounds adsorbed from highly diluted solutions onto Au and indium tin oxide electrode surfaces. Strong intramolecular charge separation (negative SPV signals up to more than 0.1 V) due to directed molecule adsorption was observed only for spirobifluorene donor–acceptor compounds with carboxylic acid moiety. SPV signals and onset energies of electronic transitions depended on ambience conditions. - Highlights: ► Fluorene donor–acceptor derivatives were adsorbed at Au and indium tin oxide. ► Surface photovoltage measurements were performed with a Kelvin-probe. ► Strong intra-molecular charge separation was observed. ► SPV signals depended on ambience conditions

  8. Development of Polymer Acceptors for Organic Photovoltaic Cells

    Directory of Open Access Journals (Sweden)

    Yujeong Kim

    2014-02-01

    Full Text Available This review provides a current status report of the various n-type polymer acceptors for use as active materials in organic photovoltaic cells (OPVs. The polymer acceptors are divided into four categories. The first section of this review focuses on rylene diimide-based polymers, including perylene diimide, naphthalene diimide, and dithienocoronene diimide-based polymers. The high electron mobility and good stability of rylene diimides make them suitable for use as polymer acceptors in OPVs. The second section deals with fluorene and benzothiadiazole-based polymers such as poly(9,9’-dioctylfluorene-co-benzothiadiazole, and the ensuing section focuses on the cyano-substituted polymer acceptors. Cyano-poly(phenylenevinylene and poly(3-cyano-4-hexylthiophene have been used as acceptors in OPVs and exhibit high electron affinity arising from the electron-withdrawing cyano groups in the vinylene group of poly(phenylenevinylene or the thiophene ring of polythiophene. Lastly, a number of other electron-deficient groups such as thiazole, diketopyrrolopyrrole, and oxadiazole have also been introduced onto polymer backbones to induce n-type characteristics in the polymer. Since the first report on all-polymer solar cells in 1995, the best power conversion efficiency obtained with these devices to date has been 3.45%. The overall trend in the development of n-type polymer acceptors is presented in this review.

  9. Shewanella oneidensis in a lactate-fed pure-culture and a glucose-fed co-culture with Lactococcus lactis with an electrode as electron acceptor

    Science.gov (United States)

    Bioelectrochemical systems (BESs) employing mixed microbial communities as biocatalysts are gaining importance as potential renewable energy, bioremediation, or biosensing devices. While we are beginning to understand how individual microbial species interact with an electrode as electron donor, li...

  10. Electrochemical migration in electronics: effect of contamination and bias conditions

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    – all together influence susceptibility of electronic PCBA to corrosion. When electronics is operating under humid conditions, the cleanliness of the PCBA becomes essential, since corrosion related failures in electronics can occur at extremely low levels of moisture and contamination. A synergetic...... climate, contamination, and bias conditions. In this work, the effect of ionic contamination such as sodium chloride and weak organic acids, as they are used in no-clean fluxes, was studied under water droplet and humidity elevation at room temperature conditions. The effect of pH and tin ion dissolution...... droplet. Overall the tendency of increase in time to electrochemical migration with decrease of duty cycle was observed. The testing of the printed circuit boards under humid conditions showed a correlation between the hygroscopic property of contaminants and leakage current measured on the boards...

  11. Moisture ingress into electronics enclosures under isothermal conditions

    International Nuclear Information System (INIS)

    Staliulionis, Ž.; Jabbari, M.; Hattel, J. H.

    2016-01-01

    The number of electronics used in outdoor environment is constantly growing. The humidity causes about 19 % of all electronics failures and, especially, moisture increases these problems due to the ongoing process of miniaturization and lower power consumption of electronic components. Moisture loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based on a 1D quasi-steady state (QSS) approximation for Fick’s second law. This QSS approach is also described with an electrical analogy which gives a fast tool in modelling of the moisture response. The same QSS method is applied to ambient water vapour variations. The obtained results are compared to an analytical solution and very good agreement is found.

  12. Moisture ingress into electronics enclosures under isothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Staliulionis, Ž.; Jabbari, M.; Hattel, J. H. [Process Modelling Group, Department of Mechanical engineering, Technical university of Denmark, Nils Koppels Allé, 2800 Kgs. Lyngby (Denmark)

    2016-06-08

    The number of electronics used in outdoor environment is constantly growing. The humidity causes about 19 % of all electronics failures and, especially, moisture increases these problems due to the ongoing process of miniaturization and lower power consumption of electronic components. Moisture loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based on a 1D quasi-steady state (QSS) approximation for Fick’s second law. This QSS approach is also described with an electrical analogy which gives a fast tool in modelling of the moisture response. The same QSS method is applied to ambient water vapour variations. The obtained results are compared to an analytical solution and very good agreement is found.

  13. Moisture ingress into electronics enclosures under isothermal conditions

    DEFF Research Database (Denmark)

    Staliulionis, Zygimantas; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    The number of electronics used in outdoor environment is constantly growing. The humidity causes about 19 % of all electronics failures and, especially, moisture increases these problems due to the ongoing process of miniaturization and lower power consumption of electronic components. Moisture...... loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based...... on a 1D quasi-steady state (QSS) approximation for Fick's second law. This QSS approach is also described with an electrical analogy which gives a fast tool in modelling of the moisture response. The same QSS method is applied to ambient water vapour variations. The obtained results are compared...

  14. Time-resolved EPR study on the photoexcited triplet state of the electron-donor-acceptor complex formed in the system of fac-tris[2-(4-octyl-phenyl) pyridine] iridium(III) and tetracene.

    Science.gov (United States)

    Zhebin, Fu; Shuhei, Yoshioka; Hisao, Murai

    2014-01-09

    The physical properties of the phosphorescent organic light-emitting diode material fac-tris(phenylpyridine) iridium(III), Ir(ppy)3, have been reported with experimental and theoretical studies. Here, the photochemical properties of the excited triplet state of partially modified fac-tris[2-(4-octyl-phenyl) pyridine] iridium(III), Ir(C8ppy)3, were investigated using time-resolved electron paramagnetic resonance (tr-EPR) and optical methods by adding tetracene in the toluene solution. The tr-EPR observation at 77 K revealed the following two species: the excited triplet state of tetracene and another triplet species with zero field splitting parameters of |D| = 0.088 cm(-1) and |E| = 0.018 cm(-1) with characteristic spin polarization. The latter species was assigned to the electron-donor-acceptor (EDA) complex formed between Ir(C8ppy)3 and tetracene. The mechanism of formation and the properties of this EDA complex, including the information on the principal axes of (3)Ir(C8ppy)3*, are discussed.

  15. Synthesis of OMS Materials and Investigation of Their Acceptor-Donor Characteristics.

    Science.gov (United States)

    Grajek, H; Paciura-Zadrożna, J; Choma, J; Michalski, E; Witkiewicz, Z

    2012-10-01

    Three ordered mesoporous siliceous (OMS) materials known as MCM41s-unmodified MCM-41C16 ("C16"), and two MCM41s with different surface functionalities: MCM-41C16-SH ("C16-SH") and MCM-41C16-NH 2 ("C16-NH 2 ")-were synthesized and studied by inverse gas chromatography in order to determine their acceptor-donor properties. The specific retention volumes of nonpolar and polar probes that were chromatographed on these ordered mesoporous silica adsorbents were evaluated under infinite dilution conditions. Two methods were employed to calculate the standard free energy of adsorption, Δ G ads , of each chromatographed probe on the basis its specific retention volume. These Δ G ads values were then employed to estimate the van der Waals contribution and the specific contribution of the free surface energy for each MCM41. DN values (donor numbers, based on the Gutmann scale) and AN* values (acceptor numbers, based on the Riddle-Fowkes scale) were employed to determine the values of parameters that characterize the ability of the MCM41s to act as electron acceptors (parameter: K A ) and donors (parameter: K D ). Considering the different compositions of the probes, each of which has different acceptor-donor properties, a new chromatographic test to supplement the Grob test is suggested.

  16. Resonance scattering and low-temperature electron mobility in HgTe-based gapless solid solutions

    International Nuclear Information System (INIS)

    Raikh, M.Eh.; Ehfros, A.L.

    1986-01-01

    Low-temperature electron mobility in a gapless semiconductor conditioned by electron resonance scattering on neutral acceptors, the levels of which are located in narrow vicinity near the Fermi level, is calculated. Mobility turns to be inverse proportional to density of acceptor states at the Fermi level. If donor concentration is rather high, then presence of a Coulomb gap at the Fermi level in the density of acceptor states conditioned by long-range character of Coulomb interaction should be taken into account for calculation of mobility. The Fermi level is placed in the tail of the acceptor state density at rather low donor concentration, and the Coulomb gap is absent at the Fermi level. A case of high acceptor concentration, when the acceptor states are delocalized at the Fermi level, is also considered

  17. Dehalogenimonas lykanthroporepellens BL-DC-9T simultaneously transcribes many rdhA genes during organohalide respiration with 1,2-DCA, 1,2-DCP, and 1,2,3-TCP as electron acceptors.

    Science.gov (United States)

    Mukherjee, Kalpataru; Bowman, Kimberly S; Rainey, Fred A; Siddaramappa, Shivakumara; Challacombe, Jean F; Moe, William M

    2014-05-01

    The genome sequence of the organohalide-respiring bacterium Dehalogenimonas lykanthroporepellensBL-DC-9(T) contains numerous loci annotated as reductive dehalogenase homologous (rdh) genes based on inferred protein sequence identity with functional dehalogenases of other bacterial species. Many of these genes are truncated, lack adjacent regulatory elements, or lack cognate genes coding for membrane-anchoring proteins typical of the functionally characterized active reductive dehalogenases of organohalide-respiring bacteria. To investigate the expression patterns of the rdh genes in D. lykanthroporepellensBL-DC-9(T), oligonucleotide primers were designed to uniquely target 25 rdh genes present in the genome as well as four putative regulatory genes. RNA extracts from cultures of strain BL-DC-9(T) actively dechlorinating three different electron acceptors, 1,2-dichloroethane, 1,2-dichloropropane, and 1,2,3-trichloropropane were reverse-transcribed and subjected to PCR amplification using rdh-specific primers. Nineteen rdh gene transcripts, including 13 full-length rdhA genes, six truncated rdhA genes, and five rdhA genes having cognate rdhB genes were consistently detected during the dechlorination of all three of the polychlorinated alkanes tested. Transcripts from all four of the putative regulatory genes were also consistently detected. Results reported here expand the diversity of bacteria known to simultaneously transcribe multiple rdh genes and provide insights into the transcription factors associated with rdh gene expression. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Impact of electronic coupling, symmetry, and planarization on one- and two-photon properties of triarylamines with one, two, or three diarylboryl acceptors.

    Science.gov (United States)

    Makarov, Nikolay S; Mukhopadhyay, Sukrit; Yesudas, Kada; Brédas, Jean-Luc; Perry, Joseph W; Pron, Agnieszka; Kivala, Milan; Müllen, Klaus

    2012-04-19

    We have performed a study of the one- and two-photon absorption properties of a systematically varied series of triarylamino-compounds with one, two, or three attached diarylborane arms arranged in linear dipolar, bent dipolar, and octupolar geometries. Two-photon fluorescence excitation spectra were measured over a wide spectral range with femtosecond laser pulses. We found that on going from the single-arm to the two- and three-arm systems, the peak in two-photon absorption (2PA) cross-section is suppressed by factors of 3-11 for the lowest excitonic level associated with the electronic coupling of the arms, whereas it is enhanced by factors of 4-8 for the higher excitonic level. These results show that the coupling of arms redistributes the 2PA cross-section between the excitonic levels in a manner that strongly favors the higher-energy excitonic level. The experimental data on one- and two-photon cross-sections, ground- and excited-state transition dipole moments, and permanent dipole moment differences between the ground and the lowest excited states were compared to the results obtained from a simple Frenkel exciton model and from highly correlated quantum-chemical calculations. It has been found that planarization of the structure around the triarylamine moiety leads to a sizable increase in peak 2PA cross-section for the lowest excitonic level of the two-arm system, whereas for the three-arm system, the corresponding peak was weakened and shifted to lower energy. Our studies show the importance of the interarm coupling, number of arms, and structural planarity on both the enhancement and the suppression of two-photon cross-sections in multiarm molecules. © 2012 American Chemical Society

  19. Electron trajectories and magnetotransport in nanopatterned graphene under commensurability conditions

    DEFF Research Database (Denmark)

    Power, Stephen; Thomsen, Morten Rishøj; Jauho, Antti-Pekka

    2017-01-01

    exceptional control of electron behavior, but it is hindered by the requirement to maintain ballistic transport over large length scales. Recent experiments have overcome this obstacle and observed distinct magnetoresistance commensurability peaks for perforated graphene sheets (antidot lattices......). Interpreting the exact mechanisms behind these peaks is of key importance, particularly in graphene, where a range of regimes are accessible by varying the electron density. In this work, a fully atomistic, device-based simulation of magnetoresistance experiments allows us to analyze both the resistance peaks...... and the current flow at commensurability conditions. Magnetoresistance spectra are found in excellent agreement with experiment, but we show that a semiclassical analysis, in terms of simple skipping or pinned orbits, is insufficient to fully describe the corresponding electron trajectories. Instead...

  20. Influence of acceptor on charge mobility in stacked π-conjugated polymers

    Science.gov (United States)

    Sun, Shih-Jye; Menšík, Miroslav; Toman, Petr; Gagliardi, Alessio; Král, Karel

    2018-02-01

    We present a quantum molecular model to calculate mobility of π-stacked P3HT polymer layers with electron acceptor dopants coupled next to side groups in random position with respect to the linear chain. The hole density, the acceptor LUMO energy and the hybridization transfer integral between the acceptor and polymer were found to be very critical factors to the final hole mobility. For a dopant LUMO energy close and high above the top of the polymer valence band we have found a significant mobility increase with the hole concentration and with the dopant LUMO energy approaching the top of the polymer valence band. Higher mobility was achieved for small values of hybridization transfer integral between polymer and the acceptor, corresponding to the case of weakly bound acceptor. Strong couplings between the polymer and the acceptor with Coulomb repulsion interactions induced from the electron localizations was found to suppress the hole mobility.

  1. Electrochemical migration in electronics: effect of contamination and bias conditions

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    on the probability for electrochemical migration was studied on surface mount chip components under water droplet conditions, as a function of applied voltage (DC and square wave unipolar/ bipolar). The leakage current and impedance was studied on the surface insulation resistance patterns precontaminated...... droplet. Overall the tendency of increase in time to electrochemical migration with decrease of duty cycle was observed. The testing of the printed circuit boards under humid conditions showed a correlation between the hygroscopic property of contaminants and leakage current measured on the boards...... effect of the aspects mentioned above makes it challenging to predict the lifetime of electronic device. The aim of this work is to investigate corrosion influencing factors, which at a later stage improve capabilities of predicting the functioning and herewith reliability of electronics under certain...

  2. Theory of Primary Photoexcitations in Donor-Acceptor Copolymers.

    Science.gov (United States)

    Aryanpour, Karan; Dutta, Tirthankar; Huynh, Uyen N V; Vardeny, Zeev Valy; Mazumdar, Sumit

    2015-12-31

    We present a generic theory of primary photoexcitations in low band gap donor-acceptor conjugated copolymers. Because of the combined effects of strong electron correlations and broken symmetry, there is considerable mixing between a charge-transfer exciton and an energetically proximate triplet-triplet state with an overall spin singlet. The triplet-triplet state, optically forbidden in homopolymers, is allowed in donor-acceptor copolymers. For an intermediate difference in electron affinities of the donor and the acceptor, the triplet-triplet state can have a stronger oscillator strength than the charge-transfer exciton. We discuss the possibility of intramolecular singlet fission from the triplet-triplet state, and how such fission can be detected experimentally.

  3. A generalized electron energy probability function for inductively coupled plasmas under conditions of nonlocal electron kinetics

    Science.gov (United States)

    Mouchtouris, S.; Kokkoris, G.

    2018-01-01

    A generalized equation for the electron energy probability function (EEPF) of inductively coupled Ar plasmas is proposed under conditions of nonlocal electron kinetics and diffusive cooling. The proposed equation describes the local EEPF in a discharge and the independent variable is the kinetic energy of electrons. The EEPF consists of a bulk and a depleted tail part and incorporates the effect of the plasma potential, Vp, and pressure. Due to diffusive cooling, the break point of the EEPF is eVp. The pressure alters the shape of the bulk and the slope of the tail part. The parameters of the proposed EEPF are extracted by fitting to measure EEPFs (at one point in the reactor) at different pressures. By coupling the proposed EEPF with a hybrid plasma model, measurements in the gaseous electronics conference reference reactor concerning (a) the electron density and temperature and the plasma potential, either spatially resolved or at different pressure (10-50 mTorr) and power, and (b) the ion current density of the electrode, are well reproduced. The effect of the choice of the EEPF on the results is investigated by a comparison to an EEPF coming from the Boltzmann equation (local electron kinetics approach) and to a Maxwellian EEPF. The accuracy of the results and the fact that the proposed EEPF is predefined renders its use a reliable alternative with a low computational cost compared to stochastic electron kinetic models at low pressure conditions, which can be extended to other gases and/or different electron heating mechanisms.

  4. High-resolution noncontact AFM and Kelvin probe force microscopy investigations of self-assembled photovoltaic donor-acceptor dyads.

    Science.gov (United States)

    Grévin, Benjamin; Schwartz, Pierre-Olivier; Biniek, Laure; Brinkmann, Martin; Leclerc, Nicolas; Zaborova, Elena; Méry, Stéphane

    2016-01-01

    Self-assembled donor-acceptor dyads are used as model nanostructured heterojunctions for local investigations by noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). With the aim to probe the photo-induced charge carrier generation, thin films deposited on transparent indium tin oxide substrates are investigated in dark conditions and upon illumination. The topographic and contact potential difference (CPD) images taken under dark conditions are analysed in view of the results of complementary transmission electron microscopy (TEM) experiments. After in situ annealing, it is shown that the dyads with longer donor blocks essentially lead to standing acceptor-donor lamellae, where the acceptor and donor groups are π-stacked in an edge-on configuration. The existence of strong CPD and surface photo-voltage (SPV) contrasts shows that structural variations occur within the bulk of the edge-on stacks. SPV images with a very high lateral resolution are achieved, which allows for the resolution of local photo-charging contrasts at the scale of single edge-on lamella. This work paves the way for local investigations of the optoelectronic properties of donor-acceptor supramolecular architectures down to the elementary building block level.

  5. Electrochemical and optical properties of a new donor–acceptor ...

    Indian Academy of Sciences (India)

    Abstract. In this communication, we report the synthesis and characterization of a new donor–acceptor type conjugated polymer carrying alternate 3 ..... Figure 3. TGA trace of the polymer P1. Table 1. Electrochemical potentials, energy levels and energy barriers for electron/hole injection for the polymer P1. Polymer. Eons.

  6. Photoactive Donor-Acceptor Composite Nanoparticles Dispersed in Water.

    Science.gov (United States)

    Parrenin, Laurie; Laurans, Gildas; Pavlopoulou, Eleni; Fleury, Guillaume; Pecastaings, Gilles; Brochon, Cyril; Vignau, Laurence; Hadziioannou, Georges; Cloutet, Eric

    2017-02-14

    A major issue that inhibits the large-scale fabrication of organic solar modules is the use of chlorinated solvents considered to be toxic and hazardous. In this work, composite particles of 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 (PC 71 BM) were obtained in water from a versatile and a ready-to-market methodology based on postpolymerization miniemulsification. Depending on the experimental conditions, size-controlled particles comprising both the electron donor and the electron acceptor were obtained and characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle neutron scattering (SANS), UV-visible absorption, and fluorescence spectroscopy. Intimate mixing of the two components was definitely asserted through PCDTBT fluorescence quenching in the composite nanoparticles. The water-based inks were used for the preparation of photovoltaic active layers that were subsequently integrated into organic solar cells.

  7. Development of helium electron cyclotron wall conditioning on TCV

    Science.gov (United States)

    Douai, D.; Goodman, T.; Isayama, A.; Fukumoto, M.; Wauters, T.; Sozzi, C.; Coda, S.; Blanchard, P.; Figini, L.; Garavaglia, S.; Miyata, Y.; Moro, A.; Ricci, D.; Silva, M.; Theiler, C.; Vartanian, S.; Verhaegh, K.; the EUROfusion MST1 Team; the TCV Team

    2018-02-01

    JT-60SA envisions electron cyclotron wall conditioning (ECWC), as wall conditioning method in the presence of the toroidal field to control fuel and impurity recycling and to improve plasma performance and reproducibility. This paper reports on Helium ECWC experiments on TCV in support of JT-60SA operation. Nearly sixty Helium conditioning discharges have been successfully produced in TCV, at a toroidal field B T  =  1.3 or 1.54 T, with gyrotrons at 82.7 GHz in X2 mode, mimicking ECWC operation in JT-60SA at the second harmonic of the EC wave. Discharge parameters were tuned in order to (i) minimize the time for the onset of ECWC plasmas, thus minimizing absorption of stray radiation by in-vessel components, (ii) improve discharge homogeneity by extending the discharge vertically and radially, and wall coverage, in particular of inboard surfaces where JT-60SA plasmas will be initiated, (iii) assess the efficiency of He-ECWC to deplete carbon walls from fuel. An optimized combination of vertical and radial magnetic fields, with amplitudes typically 0.1 to 0.6% of that of B T, has been determined, which resulted in lowest breakdown time, improved wall coverage and enhanced fuel removal. A standard ohmic D 2-plasma could be then sustained, whereas it would not have been possible without He-ECWC.

  8. Conditioning of mealybug (Hemiptera: Pseudococcidae) by Scanning Electron Microscopy

    International Nuclear Information System (INIS)

    Palma-Jimenez, Melissa; Blanco-Meneses, Monica

    2015-01-01

    The cleaning and correct observation of the mealybug specimens was determined by the conditioning methodology. The research was done in the Laboratorio del Centro de Investigacion en Estructuras Microscopicas (CIEMIC) of the Universidad de Costa Rica during the year 2012. A gradual improvement for the observation of the ultrastructures through the Scanning Electron Microscope was evidenced by the implementation of four types of methodologies. Each process was described in detail. The incorporation of 10% xylene (in some cases have been viable using ethanol at 95-100% ) was allowed to remove the wax from the body of the insect, to avoid this the collapse and to observe specific ultrastructures of the individual, they were the best results. The methodology used has reduced the time and costs in future taxonomic research of mealybug. (author) [es

  9. Phenyl vs Alkyl Polythiophene: A Solar Cell Comparison Using a Vinazene Derivative as Acceptor

    KAUST Repository

    Woo, Claire H.

    2010-03-09

    The solar cell performance of poly[3-(4-n-octyl)-phenylthiophene] (POPT) and poly(3hexylthiophene) (P3HT) are compared in devices using 4,7-bis(2-(l-(2-ethylhexyl)-4,5-dicyanoimidazol-2-yl)vinyi)benzo[c][l,2,5] -thiadiazole (EV-BT) as the electron acceptor. Despite their reduced light absorption, POPT:EV-BT devices generate higher photocurrents in both bilayer and bulk heterojunction (BHJ) architectures than analogous P3HT:EV-BT devices. Optimized POPT:EV-BT BHJ devices achieve 1.4% average efficiency, whereas the analogous P3HT devices only reach 1.1%. Morphology does not account for the large difference in performance as AFM studies of the active layer suggest, comparable levels of phase separation in the two systems. Reverse bias analysis demonstrates that P3HT devices have a higher maximum potential than POPT devices, but P3HT devices appear to be more severely limited by recombination losses under standard operating conditions. A possible explanation for the superior performance in POPT devices is that the pendant phenyl ring in POPT can twist out-of-plane and increase the separation distance with the acceptor molecule. A larger donor/acceptor separation distance can destabilize the geminate pair and lead to more efficient charge separation in POPT:EV-BT devices. Our results emphasize the importance of donor/acceptor pair interactions and its effect on charge separation, processes in polymer solar cells. © 2010 American Chemical Society.

  10. Change in electrogenic activity of the microbial fuel cell (MFC) with the function of biocathode microenvironment as terminal electron accepting condition: influence on overpotentials and bio-electro kinetics.

    Science.gov (United States)

    Srikanth, S; Venkata Mohan, S

    2012-09-01

    Influence of biocathode microenvironment as terminal electron accepting process (TEAP) on the electrogenic activity of the microbial fuel cell (MFC)/bio-electrochemical system (BES) was evaluated in concurrence with the internal losses and bio-electro kinetics. Aerobic metabolism as TEAP showed power output (37.5 ± 2.7 mW/m(2)) for extended time (240 h) over abiotic (42.5 ± 1.5 mW/m(2)) electron accepting process. On the contrary, anaerobic metabolism as TEAP showed negligible power output in spite of increased retention time due to the absence of electron acceptor. Presence of strong electron acceptor conditions in aerobic metabolism facilitated gradual and stable reduction of electrons which helped to overcome the activation over potential and other potential losses. Voltammetric and amperometric analysis witnessed higher and sustainable electron discharge against the aerobic metabolism at cathode. Bio-electro kinetic analysis also showed lower Tafel slope and electron transfer co-efficient indicating the positive impact of aerobic metabolism at cathode in decreasing the internal losses. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Electronic absorption spectroscopic studies on charge-transfer interactions in a biologically important molecule: N, N'-dimethyl-4,4'-bipyridylium chloride (paraquat or methyl viologen) as an electron acceptor

    Science.gov (United States)

    Murthy, A. S. N.; Bhardwaj, A. P.

    The charge-transfer spectra of N, N'-dimethyl-4,4'-bipyridylium chloride (paraquat, PQ 2+) with a wide range of electron donors has been investigated and the thermodynamic data determined. An estimate of the empirical energy parameters has been made using the spectroscopic and thermodynamic data, using Mulliken's theory.

  12. Application of {sup 13}C and {sup 15}N stable isotope probing to characterize RDX degrading microbial communities under different electron-accepting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Kun-Ching; Lee, Do Gyun [Zachry Department of Civil Engineering, Texas A& M University, College Station, TX 77843-3136 (United States); Fuller, Mark E.; Hatzinger, Paul B.; Condee, Charles W. [CB& I Federal Services, Lawrenceville, NJ (United States); Chu, Kung-Hui, E-mail: kchu@civil.tamu.edu [Zachry Department of Civil Engineering, Texas A& M University, College Station, TX 77843-3136 (United States)

    2015-10-30

    Highlights: • SIP characterized RDX-degrading communities under different e-accepting conditions. • Dominant RDX degradation pathways differed under different e-accepting conditions. • More complete detoxification of RDX occurred under methanogenic and sulfate-reducing conditions than under manganese(IV) and iron(III)-reducing conditions. - Abstract: This study identified microorganisms capable of using the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) or its metabolites as carbon and/or nitrogen sources under different electron-accepting conditions using {sup 13}C and {sup 15}N stable isotope probing (SIP). Mesocosms were constructed using groundwater and aquifer solids from an RDX-contaminated aquifer. The mesocosms received succinate as a carbon source and one of four electron acceptors (nitrate, manganese(IV), iron(III), or sulfate) or no additional electron acceptor (to stimulate methanogenesis). When RDX degradation was observed, subsamples from each mesocosm were removed and amended with {sup 13}C{sub 3}- or ring-{sup 15}N{sub 3}-, nitro-{sup 15}N{sub 3}-, or fully-labeled {sup 15}N{sub 6}-RDX, followed by additional incubation and isolation of labeled nucleic acids. A total of fifteen 16S rRNA sequences, clustering in α- and γ-Proteobacteria, Clostridia, and Actinobacteria, were detected in the {sup 13}C-DNA fractions. A total of twenty seven sequences were derived from different {sup 15}N-DNA fractions, with the sequences clustered in α- and γ-Proteobacteria, and Clostridia. Interestingly, sequences identified as Desulfosporosinus sp. (in the Clostridia) were not only observed to incorporate the labeled {sup 13}C or {sup 15}N from labeled RDX, but also were detected under each of the different electron-accepting conditions. The data suggest that {sup 13}C- and {sup 15}N-SIP can be used to characterize microbial communities involved in RDX biodegradation, and that the dominant pathway of RDX biodegradation may differ under different

  13. Acceptor ability of cations in reactions of donor-acceptor interaction

    International Nuclear Information System (INIS)

    Buchikhin, E.P.; Kuznetsov, A.Yu.; Chekmarev, A.M.; Bobyrenko, N.A.

    2007-01-01

    Analysis of literature data devoted to the problem of quantitative characteristics of cations in reactions of donor-acceptor interaction is represented. Relative acceptor numbers of Co 2+ , Mn 2+ , Ni 2+ , Al 3+ , Ga 3+ are determined by the method of polarography. Known relative acceptor numbers for 21 cations are systematized and linear dependence between ionization potentials and relative acceptor numbers of the rigid cations is determined [ru

  14. An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

    CERN Document Server

    Scheuerlein, C; Taborelli, M; Brown, A; Baker, M A

    2002-01-01

    The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis results are compared with electron dose dependent secondary electron and electron stimulated desorption yield measurements. Initially the electron irradiation causes a surface cleaning through electron stimulated desorption, in particular of hydrogen. During this period both the electron stimulated desorption and secondary electron yield decrease as a function of electron dose. When the electron dose exceeds 10-4 C mm-2 electron stimulated desorption yields are reduced by several orders of magnitude and the electron beam indu...

  15. Acceptor number-dependent ultrafast photo-physical properties of push-pull chromophores using time-resolved methods

    Science.gov (United States)

    Chi, Xiao-Chun; Wang, Ying-Hui; Gao, Yu; Sui, Ning; Zhang, Li-Quan; Wang, Wen-Yan; Lu, Ran; Ji, Wen-Yu; Yang, Yan-Qiang; Zhang, Han-Zhuang

    2018-04-01

    Three push-pull chromophores comprising a triphenylamine (TPA) as electron-donating moiety and functionalized β-diketones as electron acceptor units are studied by various spectroscopic techniques. The time-correlated single-photon counting data shows that increasing the number of electron acceptor units accelerates photoluminescence relaxation rate of compounds. Transient spectra data shows that intramolecular charge transfer (ICT) takes place from TPA units to β-diketones units after photo-excitation. Increasing the number of electron acceptor units would prolong the generation process of ICT state, and accelerate the excited molecule reorganization process and the relaxation process of ICT state.

  16. Dithiafulvene-based organic sensitizers using pyridine as the acceptor for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jun; Cao, Yaxiong; Liang, Xiaozhong; Zheng, Jingxia; Zhang, Fang [Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials, Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wei, Shuxian; Lu, Xiaoqing [College of Science, China University of Petroleum, Qingdao, Shandong 266555 (China); Guo, Kunpeng, E-mail: guokunpeng@tyut.edu.cn [Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials, Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Shihe, E-mail: chsyang@ust.hk [Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials, Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2017-05-01

    Three dithiafulvene-based metal-free organic sensitizers all using pyridine as the acceptor but with different π-bridges of phenyl (DTF-Py1), thienyl (DTF-Py2) and phenyl-thienyl (DTF-Py3) have been designed, synthesized and used as photosensitizers for dye-sensitized solar cells (DSCs). Introducing thienyl unit into the π-bridge, as well as extension of the π-bridge can dramatically improve their light harvesting ability and suppress the electron recombination, thus uplifting the performance of DSCs. The overall power conversion efficiency of DSC based on DTF-Py3 shows the highest efficiency of 2.61% with a short-circuit photocurrent density of 7.99 mA cm{sup -2}, an open-circuit photovoltage of 630 mV, and a fill factor of 0.52, under standard global AM 1.5 solar light condition. More importantly, the long-term stability of the DTF-Py3 based DSCs under 500 h light-soaking has been demonstrated. - Highlights: • Dithiafulvene sensitizers using pyridine ring as the acceptor were synthesized for the first time. • The power conversion efficiency of 2.61% was obtained for DTF-Py3 sensitized cell. • DTF-Py3 loaded TiO{sub 2} film shows improved light harvesting ability and suppressed electron recombination.

  17. Acceptors in II-IV Semiconductors - Incorporation and Complex Formation

    CERN Multimedia

    2002-01-01

    A strong effort is currently devoted to the investigation of defects and the electrical activation of dopant atoms in II-VI semiconductors. In particular, the knowledge about the behaviour of acceptors, prerequisite for the fabrication of p-type semiconductors, is rather limited. The perturbed $\\,{\\gamma\\gamma}$ -angular correlation technique (PAC) and the photoluminescence spectroscopy (PL) using the radioactive isotopes $^{77}\\!$Br and $^{111}\\!$Ag will be applied for investigating the behaviour of acceptor dopant atoms and their interactions with defects in II-VI semiconductors. The main topic will be the identification of the technical conditions for the incorporation of electrically active acceptors in the II-VI semiconductors ~ZnS, ZnSe, ZnTe, CdS, CdSe, and CdTe with particular emphasis on the compounds~ CdTe, ZnSe, and ZnTe. The investigations will be supplemented by first exploratory PL experiments with the group V acceptors $^{71}\\!$As and $^{121}\\!$Sb. With help of the probe $^{111}\\!$Ag, the pos...

  18. Methods for the synthesis of donor-acceptor cyclopropanes

    Science.gov (United States)

    Tomilov, Yu V.; Menchikov, L. G.; Novikov, R. A.; Ivanova, O. A.; Trushkov, I. V.

    2018-03-01

    The interest in cyclopropane derivatives is caused by the facts that, first, the three-carbon ring is present in quite a few natural and biologically active compounds and, second, compounds with this ring are convenient building blocks for the synthesis of diverse molecules (acyclic, alicyclic and heterocyclic). The carbon–carbon bonds in cyclopropane are kinetically rather inert; hence, they need to be activated to be involved in reactions. An efficient way of activation is to introduce vicinal electron-donating and electron-withdrawing substituents into the ring; these substrates are usually referred to as donor-acceptor cyclopropanes. This review gives a systematic account of the key methods for the synthesis of donor-acceptor cyclopropanes. The most important among them are reactions of nucleophilic alkenes with diazo compounds and iodonium ylides and approaches based on reactions of electrophilic alkenes with sulfur ylides (the Corey–Chaykovsky reaction). Among other methods used for this purpose, noteworthy are cycloalkylation of CH-acids, addition of α-halocarbonyl compounds to alkenes, cyclization via 1,3-elimination, reactions of alkenes with halocarbenes followed by reduction, the Simmons–Smith reaction and some other. The scope of applicability and prospects of various methods for the synthesis of donor-acceptor cyclopropanes are discussed. The bibliography includes 530 references.

  19. Non-fullerene acceptors for organic solar cells

    Science.gov (United States)

    Yan, Cenqi; Barlow, Stephen; Wang, Zhaohui; Yan, He; Jen, Alex K.-Y.; Marder, Seth R.; Zhan, Xiaowei

    2018-03-01

    Non-fullerene acceptors (NFAs) are currently a major focus of research in the development of bulk-heterojunction organic solar cells (OSCs). In contrast to the widely used fullerene acceptors (FAs), the optical properties and electronic energy levels of NFAs can be readily tuned. NFA-based OSCs can also achieve greater thermal stability and photochemical stability, as well as longer device lifetimes, than their FA-based counterparts. Historically, the performance of NFA OSCs has lagged behind that of fullerene devices. However, recent developments have led to a rapid increase in power conversion efficiencies for NFA OSCs, with values now exceeding 13%, demonstrating the viability of using NFAs to replace FAs in next-generation high-performance OSCs. This Review discusses the important work that has led to this remarkable progress, focusing on the two most promising NFA classes to date: rylene diimide-based materials and materials based on fused aromatic cores with strong electron-accepting end groups. The key structure-property relationships, donor-acceptor matching criteria and aspects of device physics are discussed. Finally, we consider the remaining challenges and promising future directions for the NFA OSCs field.

  20. Asymptotic coulombic conditions in the electron capture process

    International Nuclear Information System (INIS)

    Corchs, S.E.; Maidagan, J.M.; Rivarola, R.D.

    1990-01-01

    Several first order perturbative approximations of the transition amplitude for electronic capture are studied. Different models in which the long range Coulomb potential is represented by different internuclear dependent phases, in the initial and final wave functions, are analysed and compared. (Author). 8 refs., 2 figs

  1. Silicon passivation study under low energy electron irradiation conditions

    International Nuclear Information System (INIS)

    Cluzel, R.

    2010-01-01

    Backside illuminated thinned CMOS (Complementary Metal Oxide Semiconductor) imaging system is a technology developed to increase the signal to noise ratio and the sensibility of such sensors. This configuration is adapted to the electrons detection from the energy range of [1 - 12 keV]. The impinging electron creates by multiplication several hundreds of secondary electrons close to the surface. A P ++ highly-doped passivation layer of the rear face is required to reduce the secondary electron surface recombination rate. Thanks to the potential barrier induced by the P ++ layer, the passivation layer increases the collected charges number and so the sensor collection gain. The goal of this study is to develop some experimental methods in order to determine the effect of six different passivation processes on the collection gain. Beforehand, the energy profile deposited by an incident electron is studied with the combination of Monte-Carlo simulations and some analytical calculations. The final collection gain model shows that the mirror effect from the passivation layer is a key factor at high energies whereas the passivation layer has to be as thin as possible at low energies. A first experimental setup which consists in irradiating P ++ /N large diodes allows to study the passivation process impacts on the surface recombinations. Thanks to a second setup based on a single event upset directly on thinned CMOS sensor, passivation techniques are discriminated in term of mirror effect and the implied spreading charges. The doping atoms activation laser annealing is turn out to be a multiplication gain inhomogeneity source impacting directly the matrix uniformity. (author)

  2. Electronic Health Records: Cure-all or Chronic Condition?

    OpenAIRE

    Kimble, Chris

    2014-01-01

    International audience; Computer-based information systems feature in almost every aspect of our lives, and yet most of us receive handwritten prescriptions when we visit our doctors and rely on paper-based medical records in our healthcare. Although electronic health record (EHR) systems have long been promoted as a cost-effective and efficient alternative to this situation, clear-cut evidence of their success has not been forthcoming. An examination of some of the underlying problems that p...

  3. Contrasting performance of donor-acceptor copolymer pairs in ternary blend solar cells and two-acceptor copolymers in binary blend solar cells.

    Science.gov (United States)

    Khlyabich, Petr P; Rudenko, Andrey E; Burkhart, Beate; Thompson, Barry C

    2015-02-04

    Here two contrasting approaches to polymer-fullerene solar cells are compared. In the first approach, two distinct semi-random donor-acceptor copolymers are blended with phenyl-C61-butyric acid methyl ester (PC61BM) to form ternary blend solar cells. The two poly(3-hexylthiophene)-based polymers contain either the acceptor thienopyrroledione (TPD) or diketopyrrolopyrrole (DPP). In the second approach, semi-random donor-acceptor copolymers containing both TPD and DPP acceptors in the same polymer backbone, termed two-acceptor polymers, are blended with PC61BM to give binary blend solar cells. The two approaches result in bulk heterojunction solar cells that have the same molecular active-layer components but differ in the manner in which these molecular components are mixed, either by physical mixing (ternary blend) or chemical "mixing" in the two-acceptor (binary blend) case. Optical properties and photon-to-electron conversion efficiencies of the binary and ternary blends were found to have similar features and were described as a linear combination of the individual components. At the same time, significant differences were observed in the open-circuit voltage (Voc) behaviors of binary and ternary blend solar cells. While in case of two-acceptor polymers, the Voc was found to be in the range of 0.495-0.552 V, ternary blend solar cells showed behavior inherent to organic alloy formation, displaying an intermediate, composition-dependent and tunable Voc in the range from 0.582 to 0.684 V, significantly exceeding the values achieved in the two-acceptor containing binary blend solar cells. Despite the differences between the physical and chemical mixing approaches, both pathways provided solar cells with similar power conversion efficiencies, highlighting the advantages of both pathways toward highly efficient organic solar cells.

  4. Donor–Acceptor Oligorotaxanes Made to Order

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Subhadeep [Northwestern Univ., Evanston, IL (United States); Coskun, Ali [Northwestern Univ., Evanston, IL (United States); Friedman, Douglas C. [Northwestern Univ., Evanston, IL (United States); Olson, Mark A. [Northwestern Univ., Evanston, IL (United States); Benitez, Diego [California Institute of Technology (Caltech), Pasadena, CA (United States); Tkatchouk, Ekaterina [California Institute of Technology (Caltech), Pasadena, CA (United States); Barin, Gokhan [Northwestern Univ., Evanston, IL (United States); Yang, Jeffrey [Northwestern Univ., Evanston, IL (United States); Fahrenbach, Albert C. [Northwestern Univ., Evanston, IL (United States); Goddard, William A. [California Institute of Technology (Caltech), Pasadena, CA (United States); Stoddart, J. Fraser [Northwestern Univ., Evanston, IL (United States)

    2011-01-01

    Five donor–acceptor oligorotaxanes made up of dumbbells composed of tetraethylene glycol chains, interspersed with three and five 1,5-dioxynaphthalene units, and terminated by 2,6-diisopropylphenoxy stoppers, have been prepared by the threading of discrete numbers of cyclobis(paraquat-p-phenylene) rings, followed by a kinetically controlled stoppering protocol that relies on click chemistry. The well-known copper(I)-catalyzed alkyne–azide cycloaddition between azide functions placed at the ends of the polyether chains and alkyne-bearing stopper precursors was employed during the final kinetically controlled template-directed synthesis of the five oligorotaxanes, which were characterized subsequently by ¹H NMR spectroscopy at low temperature (233 K) in deuterated acetonitrile. The secondary structures, as well as the conformations, of the five oligorotaxanes were unraveled by spectroscopic comparison with the dumbbell and ring components. By focusing attention on the changes in chemical shifts of some key probe protons, obtained from a wide range of low-temperature spectra, a picture emerges of a high degree of folding within the thread protons of the dumbbells of four of the five oligorotaxanes—the fifth oligorotaxane represents a control compound in effect—brought about by a combination of C[BOND]H···O and π–π stacking interactions between the π-electron-deficient bipyridinium units in the rings and the π-electron-rich 1,5-dioxynaphthalene units and polyether chains in the dumbbells. The secondary structures of a foldamer-like nature have received further support from a solid-state superstructure of a related [3]pseudorotaxane and density functional calculations performed thereon.

  5. Modulation of Donor-Acceptor Distance in a Series of Carbazole Push-Pull Dyes; A Spectroscopic and Computational Study

    Directory of Open Access Journals (Sweden)

    Joshua J. Sutton

    2018-02-01

    Full Text Available A series of eight carbazole-cyanoacrylate based donor-acceptor dyes were studied. Within the series the influence of modifying the thiophene bridge, linking donor and acceptor and a change in the nature of the acceptor, from acid to ester, was explored. In this joint experimental and computational study we have used electronic absorbance and emission spectroscopies, Raman spectroscopy and computational modeling (density functional theory. From these studies it was found that extending the bridge length allowed the lowest energy transition to be systematically red shifted by 0.12 eV, allowing for limited tuning of the absorption of dyes using this structural motif. Using the aforementioned techniques we demonstrate that this transition is charge transfer in nature. Furthermore, the extent of charge transfer between donor and acceptor decreases with increasing bridge length and the bridge plays a smaller role in electronically mixing with the acceptor as it is extended.

  6. Donor-Acceptor Block Copolymers: Synthesis and Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi

    2014-04-01

    Full Text Available Fullerene derivatives have been widely used for conventional acceptor materials in organic photovoltaics (OPVs because of their high electron mobility. However, there are also considerable drawbacks for use in OPVs, such as negligible light absorption in the visible-near-IR regions, less compatibility with donor polymeric materials and high cost for synthesis and purification. Therefore, the investigation of non-fullerene acceptor materials that can potentially replace fullerene derivatives in OPVs is increasingly necessary, which gives rise to the possibility of fabricating all-polymer (polymer/polymer solar cells that can deliver higher performance and that are potentially cheaper than fullerene-based OPVs. Recently, considerable attention has been paid to donor-acceptor (D-A block copolymers, because of their promising applications as fullerene alternative materials in all-polymer solar cells. However, the synthesis of D-A block copolymers is still a challenge, and therefore, the establishment of an efficient synthetic method is now essential. This review highlights the recent advances in D-A block copolymers synthesis and their applications in all-polymer solar cells.

  7. Organic Donor-Acceptor Complexes as Novel Organic Semiconductors.

    Science.gov (United States)

    Zhang, Jing; Xu, Wei; Sheng, Peng; Zhao, Guangyao; Zhu, Daoben

    2017-07-18

    Organic donor-acceptor (DA) complexes have attracted wide attention in recent decades, resulting in the rapid development of organic binary system electronics. The design and synthesis of organic DA complexes with a variety of component structures have mainly focused on metallicity (or even superconductivity), emission, or ferroelectricity studies. Further efforts have been made in high-performance electronic investigations. The chemical versatility of organic semiconductors provides DA complexes with a great number of possibilities for semiconducting applications. Organic DA complexes extend the semiconductor family and promote charge separation and transport in organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). In OFETs, the organic complex serves as an active layer across extraordinary charge pathways, ensuring the efficient transport of induced charges. Although an increasing number of organic semiconductors have been reported to exhibit good p- or n-type properties (mobilities higher than 1 or even 10 cm 2 V -1 s -1 ), critical scientific challenges remain in utilizing the advantages of existing semiconductor materials for more and wider applications while maintaining less complicated synthetic or device fabrication processes. DA complex materials have revealed new insight: their unique molecular packing and structure-property relationships. The combination of donors and acceptors could offer practical advantages compared with their unimolecular materials. First, growing crystals of DA complexes with densely packed structures will reduce impurities and traps from the self-assembly process. Second, complexes based on the original structural components could form superior mixture stacking, which can facilitate charge transport depending on the driving force in the coassembly process. Third, the effective use of organic semiconductors can lead to tunable band structures, allowing the operation mode (p- or n-type) of the transistor to be

  8. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    OpenAIRE

    Li, W; Thorne, RM; Bortnik, J; Baker, DN; Reeves, GD; Kanekal, SG; Spence, HE; Green, JC

    2015-01-01

    ©2015. American Geophysical Union. All Rights Reserved. Determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations ( > 1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly c...

  9. Complex influence of space environment on materials and electronic devices in the conditions of microgravity

    Science.gov (United States)

    Musabayev, T.; Zhantayev, Zh.; Grichshenko, V.

    2016-09-01

    The paper presents a new physical model describing the processes in materials and electronic devices under the influence of cosmic rays in microgravity. The model identifies specific features of formation of the area of radiation defects (ARD) in the electronic materials in microgravity. The mechanism of interaction between the ARD and memory modules in microgravity causing malfunction and failure of onboard electronics is considered. The results of failure of memory modules under real conditions are presented.

  10. Local Intermolecular Order Controls Photoinduced Charge Separation at Donor/Acceptor Interfaces in Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Feier, Hilary M.; Reid, Obadiah G.; Pace, Natalie A.; Park, Jaehong; Bergkamp, Jesse J.; Sellinger, Alan; Gust, Devens; Rumbles, Garry

    2016-03-23

    How free charge is generated at organic donor-acceptor interfaces is an important question, as the binding energy of the lowest energy (localized) charge transfer states should be too high for the electron and hole to escape each other. Recently, it has been proposed that delocalization of the electronic states participating in charge transfer is crucial, and aggregated or otherwise locally ordered structures of the donor or the acceptor are the precondition for this electronic characteristic. The effect of intermolecular aggregation of both the polymer donor and fullerene acceptor on charge separation is studied. In the first case, the dilute electron acceptor triethylsilylhydroxy-1,4,8,11,15,18,22,25-octabutoxyphthalocyaninatosilicon(IV) (SiPc) is used to eliminate the influence of acceptor aggregation, and control polymer order through side-chain regioregularity, comparing charge generation in 96% regioregular (RR-) poly(3-hexylthiophene) (P3HT) with its regiorandom (RRa-) counterpart. In the second case, ordered phases in the polymer are eliminated by using RRa-P3HT, and phenyl-C61-butyric acid methyl ester (PC61BM) is used as the acceptor, varying its concentration to control aggregation. Time-resolved microwave conductivity, time-resolved photoluminescence, and transient absorption spectroscopy measurements show that while ultrafast charge transfer occurs in all samples, long-lived charge carriers are only produced in films with intermolecular aggregates of either RR-P3HT or PC61BM, and that polymer aggregates are just as effective in this regard as those of fullerenes.

  11. On the acceptor-related photoluminescence spectra of GaAs quantum-wire microcrystals: A model calculation

    International Nuclear Information System (INIS)

    Oliveira, L.E.; Porras Montenegro, N.; Latge, A.

    1992-07-01

    The acceptor-related photoluminescence spectrum of a GaAs quantum-wire microcrystal is theoretically investigated via a model calculation within the effective-mass approximation, with the acceptor envelope wave functions and binding energies calculated through a variational procedure. Typical theoretical photoluminescence spectra show two peaks associated to transitions from the n = 1 conduction subband electron gas to acceptors at the on-center and on-edge positions in the wire in good agreement with the recent experimental results by Hirum et al. (Appl. Phys. Lett. 59, 431 (1991)). (author). 14 refs, 3 figs

  12. Blinking fluorescence of single donor-acceptor pairs: important role of "dark'' states in resonance energy transfer via singlet levels.

    Science.gov (United States)

    Osad'ko, I S; Shchukina, A L

    2012-06-01

    The influence of triplet levels on Förster resonance energy transfer via singlet levels in donor-acceptor (D-A) pairs is studied. Four types of D-A pair are considered: (i) two-level donor and two-level acceptor, (ii) three-level donor and two-level acceptor, (iii) two-level donor and three-level acceptor, and (iv) three-level donor and three-level acceptor. If singlet-triplet transitions in a three-level acceptor molecule are ineffective, the energy transfer efficiency E=I_{A}/(I_{A}+I_{D}), where I_{D} and I_{A} are the average intensities of donor and acceptor fluorescence, can be described by the simple theoretical equation E(F)=FT_{D}/(1+FT_{D}). Here F is the rate of energy transfer, and T_{D} is the donor fluorescence lifetime. In accordance with the last equation, 100% of the donor electronic energy can be transferred to an acceptor molecule at FT_{D}≫1. However, if singlet-triplet transitions in a three-level acceptor molecule are effective, the energy transfer efficiency is described by another theoretical equation, E(F)=F[over ¯](F)T_{D}/[1+F[over ¯](F)T_{D}]. Here F[over ¯](F) is a function of F depending on singlet-triplet transitions in both donor and acceptor molecules. Expressions for the functions F[over ¯](F) are derived. In this case the energy transfer efficiency will be far from 100% even at FT_{D}≫1. The character of the intensity fluctuations of donor and acceptor fluorescence indicates which of the two equations for E(F) should be used to find the value of the rate F. Therefore, random time instants of photon emission in both donor and acceptor fluorescence are calculated by the Monte Carlo method for all four types of D-A pair. Theoretical expressions for start-stop correlators (waiting time distributions) in donor and acceptor fluorescence are derived. The probabilities w_{N}^{D}(t) and w_{N}^{A}(t) of finding N photons of donor and acceptor fluorescence in the time interval t are calculated for various values of the energy

  13. Diphenylmethanofullerenes: New and efficient acceptors in bulk-heterojunction solar cells

    NARCIS (Netherlands)

    Riedel, I; von Hauff, E; Parisi, H; Martin, N.; Giacalone, F; Dyakonov, Vladimir

    2005-01-01

    A novel fullerene derivative, 1,1-bis(4,4′-dodecyloxyphenyl)-(5,6) C61, diphenylmethanofullerene (DPM-12), has been investigated as a possible electron acceptor in photovoltaic devices, in combination with two different conjugated polymers poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-para-phenylene

  14. Organic Materials in the Undergraduate Laboratory: Microscale Synthesis and Investigation of a Donor-Acceptor Molecule

    Science.gov (United States)

    Pappenfus, Ted M.; Schliep, Karl B.; Dissanayake, Anudaththa; Ludden, Trevor; Nieto-Ortega, Belen; Lopez Navarrete, Juan T.; Ruiz Delgado, M. Carmen; Casado, Juan

    2012-01-01

    A series of experiments for undergraduate courses (e.g., organic, physical) have been developed in the area of small molecule organic materials. These experiments focus on understanding the electronic and redox properties of a donor-acceptor molecule that is prepared in a convenient one-step microscale reaction. The resulting intensely colored…

  15. Perylene-Diimide Based Donor-Acceptor-Donor Type Small-Molecule Acceptors for Solution-Processable Organic Solar Cells

    Science.gov (United States)

    Ganesamoorthy, Ramasamy; Vijayaraghavan, Rajagopalan; Sakthivel, Pachagounder

    2017-12-01

    Development of nonfullerene acceptors plays an important role in the commercial availability of plastic solar cells. We report herein synthesis of bay-substituted donor-acceptor-donor (D-A-D)-type perylene diimide (PDI)-based small molecules (SM-1 to SM-4) by Suzuki coupling method and their use as acceptors in bulk heterojunction organic solar cells (BHJ-OSCs) with poly(3-hexylthiophene) (P3HT) polymer donor. We varied the number of electron-rich thiophene units and the solubilizing side chains and also evaluated the optical and electrochemical properties of the small molecules. The synthesized small molecules were confirmed by Fourier-transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and high-resolution mass spectroscopy (HR-MS). The small molecules showed extensive and strong absorption in the ultraviolet-visible (UV-Vis) region up to 750 nm, with bandgap (E_{{g}}^{{opt}} ) reduced below P3HT polymer donor showed maximum power conversion efficiency (PCE) of 0.19% with V oc of 0.30 V, J sc of 1.72 mA cm-2, and fill factor (FF) of 37%. The PCE decreased with the number of thiophene units. The PCE of SM-2 was lower than that of SM-1. This difference in PCE can be explained by the higher aggregation tendency of the bithiophene compared with the thiophene unit. Introduction of the solubilizing group in the bay position increased the aggregation property, leading to much lower PCE than for the small molecules without solubilizing group.

  16. Comparison of acceptor properties for interaction of TCNE and DDQ ...

    African Journals Online (AJOL)

    ... with tetracyanoethylene and 2,3-dichloro-5,6-dicyanobezoquinone as acceptors result in charge-transfer adducts of composition 2:1 of acceptor to donor, [(acceptor)2(donor)]. Formation constants, K, as well as the thermodynamic parameters, ΔH°, ΔS°, and ΔG° were determined by UV-Vis titration method for the adducts.

  17. α,β-Unsubstituted meso-Positioning Thienyl BODIPY: A Promising Electron Deficient Building Block for the Development of Near Infrared (NIR) p-type Donor-Acceptor (D-A) Conjugated Polymers

    KAUST Repository

    Squeo, Benedetta

    2018-02-27

    It is demonstrated that α,β-unsubstituted meso-positioning thienyl BODIPY is an electron deficient unit that leads to the development of ultra low optical band gap (Egopt < 1 eV) π-conjugated D-A quarterthiophene polymers. Furthermore, it is revealed that the optoelectronic, electrochemical and charge transporting properties of the resulting α,β-unsubstituted meso-positioning thienyl BODIPY quaterthiophene-based polymers are alkyl side chain positioning dependent. Tail-to-tail (TT) positioning of the alkyl side chains at the two central thiophenes of the quaterthiophene segment results to lower Egopt, higher energy levels and increased hole mobility as compared to head-to-head (HH) positioning. Finally, even though the synthesized polymers exhibit high electron affinity, higher even to that of the fullerene derivative [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), they present only p-type behaviour in field effect transistors (FETs) independent to the alkyl side chain positioning.

  18. A rhodanine flanked nonfullerene acceptor for solution-processed organic photovoltaics

    KAUST Repository

    Holliday, Sarah

    2015-01-21

    A novel small molecule, FBR, bearing 3-ethylrhodanine flanking groups was synthesized as a nonfullerene electron acceptor for solution-processed bulk heterojunction organic photovoltaics (OPV). A straightforward synthesis route was employed, offering the potential for large scale preparation of this material. Inverted OPV devices employing poly(3-hexylthiophene) (P3HT) as the donor polymer and FBR as the acceptor gave power conversion efficiencies (PCE) up to 4.1%. Transient and steady state optical spectroscopies indicated efficient, ultrafast charge generation and efficient photocurrent generation from both donor and acceptor. Ultrafast transient absorption spectroscopy was used to investigate polaron generation efficiency as well as recombination dynamics. It was determined that the P3HT:FBR blend is highly intermixed, leading to increased charge generation relative to comparative devices with P3HT:PC60BM, but also faster recombination due to a nonideal morphology in which, in contrast to P3HT:PC60BM devices, the acceptor does not aggregate enough to create appropriate percolation pathways that prevent fast nongeminate recombination. Despite this nonoptimal morphology the P3HT:FBR devices exhibit better performance than P3HT:PC60BM devices, used as control, demonstrating that this acceptor shows great promise for further optimization.

  19. Study of the Contributions of Donor and Acceptor Photoexcitations to Open Circuit Voltage in Bulk Heterojunction Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Douglas Yeboah

    2017-10-01

    Full Text Available One of the key parameters in determining the power conversion efficiency (PCE of bulk heterojunction (BHJ organic solar cells (OSCs is the open circuit voltage . The processes of exciting the donor and acceptor materials individually in a BHJ OSC are investigated and are found to produce two different expressions for . Using the contributions of electron and hole quasi-Fermi levels and charge carrier concentrations, the two different expressions are derived as functions of the energetics of the donor and acceptor materials and the photo-generated charge carrier concentrations, and calculated for a set of donor-acceptor blends. The simultaneous excitation of both the donor and acceptor materials is also considered and the corresponding , which is different from the above two, is derived. The calculated from the photoexcitation of the donor is found to be somewhat comparable with that obtained from the photoexcitation of the acceptor in most combinations of the donor and acceptor materials considered here. It is also found that the calculated from the simultaneous excitations of donor and acceptor in BHJ OSCs is also comparable with the other two . All three thus derived produce similar results and agree reasonably well with the measured values. All three depend linearly on the concentration of the photoexcited charge carriers and hence incident light intensity, which agrees with experimental results. The outcomes of this study are expected to help in finding materials that may produce higher and hence enhanced PCE in BHJ OSCs.

  20. Charge transfer from first principles: self-consistent GW applied to donor-acceptor systems

    Science.gov (United States)

    Atalla, Viktor; Caruso, Fabio; Rubio, Angel; Scheffler, Matthias; Rinke, Patrick

    2015-03-01

    Charge transfer in donor-acceptor systems (DAS) is determined by the relative alignment between the frontier orbitals of the donor and the acceptor. Semi-local approximations to density functional theory (DFT) may give a qualitatively wrong level alignment in DAS, leading to unphysical fractional electron transfer in weakly bound donor-acceptor pairs. GW calculations based on first-order perturbation theory (G0W0) correct the level alignment, but leave unaffected the electron density. We demonstrate that self-consistent GW (sc GW) provides an ideal framework for the description of charge transfer in DAS. Moreover, sc GW seamlessly accounts for many-body correlations and van der Waals interactions. As in G0W0 , the sc GW level alignment is in agreement with experimental reference data. However in sc GW , also the electron density is treated at the GW level and, therefore, it is consistent with the level alignment between donor and acceptor leading to a qualitatively correct description of charge-transfer properties.

  1. Recent research progress of polymer donor/polymer acceptor blend solar cells

    OpenAIRE

    Benten, Hiroaki; Mori, Daisuke; Ohkita, Hideo; Ito, Shinzaburo

    2016-01-01

    Polymer/polymer blend solar cells based on a blend of two types of conjugated polymers acting as an electron donor (hole transport) and acceptor (electron transport) have recently attracted considerable attention, because they have numerous potential advantages over conventional polymer/fullerene blend solar cells. The highest power conversion efficiency (PCE) was slightly above 2% five years ago, whereas PCEs of beyond 8% are the state-of-the-art today, and the efficiency gap between polymer...

  2. Natural alkaloid Luotonin A and its affixed acceptor molecules: Serum albumin binding studies.

    Science.gov (United States)

    Kesavan, Mookkandi Palsamy; Kumar, Gujuluva Gangatharan Vinoth; Anitha, Kandasamy; Ravi, Lokesh; Raja, Jeyaraj Dhaveethu; Rajagopal, Gurusamy; Rajesh, Jegathalaprathaban

    2017-08-01

    Effective interaction of natural alkaloid Luotonin A (L) and its affixed acceptor molecules 1 and 2 with donor molecule as Bovine serum albumin (BSA) at various pH (4.0, 7.4 and 10.0) medium have been demonstrated using various conventional spectroscopic techniques. These analyses provide some valuable features on the interaction between BSA and acceptor molecules (L, 1 and 2). From the absorption and fluorescence spectral titration studies, the formation of ground-state complexes between the acceptor molecules (L, 1 and 2) and the BSA have been confirmed. The results of the afore titrations analysis reveal that, the strong binding of receptor 1 with BSA (K app 5.68×10 4 M -1 ; K SV 1.86×10 6 Lmol -1 ; K a 6.42×10 5 Lmol -1 ; K ass 8.09×10 6 M -1 ; ΔG -33.35kJ/mol) at physiological pH medium (7.4) than other receptor molecules 2 and L. The Förster resonance energy transfer (FRET) efficiency between the tryptophan (Trp) residues of BSA and acceptor molecules L, 1 and 2 during the interaction, are 28.85, 85.24 and 53.25 % respectively. The superior binding efficacy of acceptor 1 at physiological pH condition has been further confirmed by FT-IR and Raman spectral analysis methods. Moreover, theoretical docking studies of acceptors L, 1 and 2 towards HSA have been demonstrated to differentiate their binding behaviours. It reveals that, acceptor 1 has the strongest binding ability with HSA through two hydrogen bonding and the Atomic contact energy (ACE) value of -483.96kcal/mol. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Acceptor-oxygen vacancy defect dipoles and fully coordinated defect centers in a ferroelectric perovskite lattice: Electron paramagnetic resonance analysis of Mn2+ in single crystal BaTiO3

    Science.gov (United States)

    Maier, R. A.; Pomorski, T. A.; Lenahan, P. M.; Randall, C. A.

    2015-10-01

    Defect dipoles are significant point defects in perovskite oxides as a result of their impact on oxygen vacancy dynamics. Electron paramagnetic resonance (EPR) was used to investigate the local defect structure of single crystal BaTiO3 doped with manganese. These results, along with a re-analysis of literature data, do not support the conclusion that transition metal-oxygen vacancy nearest neighbor defect dipoles ( M nT i ″ - VO • • ) × in ferroelectric BaTiO3 are majority defect centers as previously reported. Local symmetry analysis of the zero-field splitting term of the spin Hamiltonian supports the assignment of fully coordinated defect centers as opposed to defect dipoles for resonance signals at geff ˜ 2. A newly discovered defect center with g⊥ ˜ 6 is observed in the manganese doped system, and it is argued that this defect center belongs to an associated defect complex or defect dipole. This newly reported strong axial defect center, however, is present in small, minor concentrations compared to the well-known Mn2+ center with zero-field splitting of D ˜ 645 MHz. In regard to relative concentration, it is concluded that the dominant point defect related to the Mn2+ ion doped in BaTiO3 corresponds to B-site substitution with six nearest neighbor anions in octahedral coordination.

  4. Effect of storage conditions on graft of polypropylene non-woven fabric induced by electron beam

    International Nuclear Information System (INIS)

    Lee, Jin Young; Jeun, Joon Pyo; Kang, Phil Hyun

    2015-01-01

    In this study, we fabricated effect of storage conditions on graft of polypropylene (PP) non-woven fabric induced by electron beam. The electron beam irradiations on PP non-woven fabric were carried out over a range of irradiation doses from 25 to 100 kGy to make free radicals on fabric surface. The radical measurement was established by electron spin resonance (ESR) for confirming the changes of the alkyl radical and peroxy radical according to effect of storage time, storage temperature and atmosphere. It was observed that the free radicals were increased with irradiation dose and decreased with storage time due to the continuous oxidation. However, the radical extinction was significantly delayed due to reduced mobility of radicals at extremely low temperature. The degree of graft based on the analysis of ESR was investigated. The conditions of graft reaction were set at a temperature: 60 degrees Celcius, reaction time: 6 hours and styrene monomer concentration: 20 wt%

  5. Effect of storage conditions on graft of polypropylene non-woven fabric induced by electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Young; Jeun, Joon Pyo; Kang, Phil Hyun [Radiation Research Dvision for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup(Korea, Republic of)

    2015-05-15

    In this study, we fabricated effect of storage conditions on graft of polypropylene (PP) non-woven fabric induced by electron beam. The electron beam irradiations on PP non-woven fabric were carried out over a range of irradiation doses from 25 to 100 kGy to make free radicals on fabric surface. The radical measurement was established by electron spin resonance (ESR) for confirming the changes of the alkyl radical and peroxy radical according to effect of storage time, storage temperature and atmosphere. It was observed that the free radicals were increased with irradiation dose and decreased with storage time due to the continuous oxidation. However, the radical extinction was significantly delayed due to reduced mobility of radicals at extremely low temperature. The degree of graft based on the analysis of ESR was investigated. The conditions of graft reaction were set at a temperature: 60 degrees Celcius, reaction time: 6 hours and styrene monomer concentration: 20 wt%.

  6. In-situ transmission electron microscopy growth of nanoparticles under extreme conditions

    International Nuclear Information System (INIS)

    Luce, F. P.; Azevedo, G. de M.; Baptista, D. L.; Zawislak, F. C.; Oliviero, E.; Fichtner, P. F. P.

    2016-01-01

    The formation and time resolved behavior of individual Pb nanoparticles embedded in silica have been studied by in-situ transmission electron microscopy observations at high temperatures (400–1100 °C) and under 200 keV electron irradiation. It is shown that under such extreme conditions, nanoparticles can migrate at long distances presenting a Brownian-like behavior and eventually coalesce. The particle migration phenomenon is discussed considering the influence of the thermal energy and the electron irradiation effects on the atomic diffusion process which is shown to control particle migration. These results and comparison with ex-situ experiments tackle the stability and the microstructure evolution of nanoparticles systems under extreme conditions. It elucidates on the effects of energetic particle irradiation-annealing treatments either as a tool or as a detrimental issue that could hamper their long-term applications in radiation-harsh environments such as in space or nuclear sectors

  7. In-situ transmission electron microscopy growth of nanoparticles under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Luce, F. P.; Azevedo, G. de M.; Baptista, D. L.; Zawislak, F. C. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970 (Brazil); Oliviero, E. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), CNRS-IN2P3-Université Paris-Sud, 91405 Orsay-Campus (France); Fichtner, P. F. P. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970 (Brazil); Escola de Engenharia, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970 (Brazil)

    2016-01-21

    The formation and time resolved behavior of individual Pb nanoparticles embedded in silica have been studied by in-situ transmission electron microscopy observations at high temperatures (400–1100 °C) and under 200 keV electron irradiation. It is shown that under such extreme conditions, nanoparticles can migrate at long distances presenting a Brownian-like behavior and eventually coalesce. The particle migration phenomenon is discussed considering the influence of the thermal energy and the electron irradiation effects on the atomic diffusion process which is shown to control particle migration. These results and comparison with ex-situ experiments tackle the stability and the microstructure evolution of nanoparticles systems under extreme conditions. It elucidates on the effects of energetic particle irradiation-annealing treatments either as a tool or as a detrimental issue that could hamper their long-term applications in radiation-harsh environments such as in space or nuclear sectors.

  8. Conjugated donor-acceptor-acceptor (D-A-A) molecule for organic nonvolatile resistor memory.

    Science.gov (United States)

    Dong, Lei; Li, Guangwu; Yu, An-Dih; Bo, Zhishan; Liu, Cheng-Liang; Chen, Wen-Chang

    2014-12-01

    A new donor-acceptor-acceptor (D-A-A) type of conjugated molecule, N-(4-(N',N'-diphenyl)phenylamine)-4-(4'-(2,2-dicyanovinyl)phenyl) naphthalene-1,8-dicarboxylic monoimide (TPA-NI-DCN), consisting of triphenylamine (TPA) donors and naphthalimide (NI)/dicyanovinylene (DCN) acceptors was synthesized and characterized. In conjunction with previously reported D-A based materials, the additional DCN moiety attached as end group in the D-A-A configuration can result in a stable charge transfer (CT) and charge-separated state to maintain the ON state current. The vacuum-deposited TPA-NI-DCN device fabricated as an active memory layer was demonstrated to exhibit write-once-read-many (WORM) switching characteristics of organic nonvolatile memory due to the strong polarity of the TPA-NI-DCN moiety. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Evaluating transmission electron microscopy as a method for assessing the condition of archaeological wool

    DEFF Research Database (Denmark)

    Scharff, Annemette Bruselius; Jørgensen, Lise Bolt

    2017-01-01

    Transmission electron microscopy (TEM) was investigated to clarify the applicability of the method for assessing the condition of archaeological textiles from waterlogged environments. A description and evaluation of the TEM protocol is presented and the method was tested on new and artificially...

  10. 76 FR 14795 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Flight Control System Mode...

    Science.gov (United States)

    2011-03-18

    ... electronic flight control system. The applicable airworthiness regulations do not contain adequate or.... The FAA must also issue a finding of regulatory adequacy pursuant to section 611 of Public Law 92-574, the ``Noise Control Act of 1972.'' The FAA issues special conditions, as defined in 14 CFR 11.19, in...

  11. Probing the local, electronic and magnetic structure of matter under extreme conditions of temperature and pressure

    DEFF Research Database (Denmark)

    Torchio, R.; Boccato, S.; Cerantola, V.

    2016-01-01

    In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy-dispersive...

  12. Acceptor and Excitation Density Dependence of the Ultrafast Polaron Absorption Signal in Donor-Acceptor Organic Solar Cell Blends.

    Science.gov (United States)

    Zarrabi, Nasim; Burn, Paul L; Meredith, Paul; Shaw, Paul E

    2016-07-21

    Transient absorption spectroscopy on organic semiconductor blends for solar cells typically shows efficient charge generation within ∼100 fs, accounting for the majority of the charge carriers. In this Letter, we show using transient absorption spectroscopy on blends containing a broad range of acceptor content (0.01-50% by weight) that the rise of the polaron signal is dependent on the acceptor concentration. For low acceptor content (10%) most polarons are generated within 200 fs. The rise time in blends with low acceptor content was also found to be sensitive to the pump fluence, decreasing with increasing excitation density. These results indicate that the sub-100 fs rise of the polaron signal is a natural consequence of both the high acceptor concentrations in many donor-acceptor blends and the high excitation densities needed for transient absorption spectroscopy, which results in a short average distance between the exciton and the donor-acceptor interface.

  13. A Review of the Condition Monitoring of Capacitors in Power Electronic Converters

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Blaabjerg, Frede

    2015-01-01

    Capacitor is one of the reliability critical components in power electronic systems. In the last two decades, many efforts in the academic research have been devoted to the condition monitoring of capacitors to estimate their health status. Industry applications demand more reliable power...... electronics products with preventive maintenance. Nevertheless, most of the developed capacitor condition monitoring technologies are rarely adopted by industry due to the complexity, increased cost and other relevant issues. An overview of the prior-art research in this area is therefore needed to justify....... Therefore, this paper firstly classifies the capacitor condition monitoring methods into three categories, then the respective technology evolution from 1993 to 2015 is summarized. Remarks on the state-of-the-art research and the future opportunities targeting for practical industry applications are given....

  14. A Review of the Condition Monitoring of Capacitors in Power Electronic Converters

    DEFF Research Database (Denmark)

    Soliman, Hammam Abdelaal Hammam; Wang, Huai; Blaabjerg, Frede

    2016-01-01

    Capacitors are one type of reliability-critical components in power electronic systems. In the last two decades, many efforts in academic research have been devoted to the condition monitoring of capacitors to estimate their health status. Industry applications are demanding more reliable power...... electronics products with preventive maintenance. Nevertheless, most of the developed capacitor condition monitoring technologies are rarely adopted by industry due to the complexity, increased cost, and other relevant issues. An overview of the prior-art research in this area is therefore needed to justify......, this paper first classifies the capacitor condition monitoring methods into three categories, then the respective technology evolution in the last two decades is summarized. Finally, the state-of-the-art research and the future opportunities targeting for industry applications are given....

  15. Acceptor and donor levels of 3d impurities at interstitial sites in GaAs

    International Nuclear Information System (INIS)

    Scolfaro, L.M.R.; Fazzio, A.

    1988-01-01

    Results are presented for the electronic structure of 3d transition-metal intersititial impurities in GaAs. Both anion and cation intersititial defect sites of high-symmetry are considered. The existence of acceptor nd donor states in the gap for impurities at the anion interstitial site is investigated, including many-electron corrections to the one-electron energy levels. These results show that the trend for the 3d-induced t 2 states is very similar in both tetrahedral interstitial sites. It is found that Co, Fe, Mn and Cr could present donor levels in the gap. Acceptor levels are predicted to occur in the gap only for interstitial Co and Mn. (author) [pt

  16. An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

    OpenAIRE

    Scheuerlein, C; Hilleret, Noël; Taborelli, M; Brown, A; Baker, M A

    2002-01-01

    The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis resu...

  17. Blink Rate and Incomplete Blinks in Six Different Controlled Hard-Copy and Electronic Reading Conditions.

    Science.gov (United States)

    Argilés, Marc; Cardona, Genís; Pérez-Cabré, Elisabet; Rodríguez, Margarita

    2015-10-01

    To evaluate spontaneous eye blink rate (SEBR) and percentage of incomplete blinks in different hard-copy and visual display terminal (VDT) reading conditions, compared with baseline conditions. A sample of 50 participants (29 females, age range, 18-74 years) were recruited for this study. All participants had good ocular health and reported no symptoms of dry eye (OSDI score landscape picture at 2 m (baseline) and during six different, 6-minute controlled reading experimental conditions. Texts were presented in electronic (tablet and computer display at 100% and 330% zoom levels) and hard-copy (text in book position in silence and aloud and text pasted on the computer display) formats. Video analysis was subsequently conducted to assess blink parameters. All reading conditions resulted in a decrease in SEBR when compared with baseline conditions (all P Spanish Abstract.

  18. In vitro fermentation of alternansucrase raffinose acceptor products by human gut bacteria

    Science.gov (United States)

    In this work, in vitro fermentation of alternansucrase raffinose acceptor products, previously fractionated according to their degree of polymerization (DP; from DP4 to DP10) was carried out using pH-controlled small scale batch cultures at 37ºC under anaerobic conditions with human faeces. Bifidog...

  19. Molecular designing of novel ternary copolymers of donor-acceptor polymers using genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Vinita [Department of Chemistry, University of Delhi, Delhi 110 007 (India); Bakhshi, A.K., E-mail: akbakhshi2000@yahoo.com [Department of Chemistry, University of Delhi, Delhi 110 007 (India)

    2010-08-03

    Graphical abstract: Alternate arrangement of donor acceptor moieties in the carbon backbone chain of an organic conjugated polymer is capable of inducing charge transfer and affects the electronic properties of the copolymer. Genetic algorithm along with simple NFC (negative factor counting) and IIM (inverse iteration method) has been used to optimize the properties of novel ternary copolymers based on polypyrrole PPy, polythiophene PTh and polyfuran PFu (as donor moieties) and containing >C=O and >C=CF{sub 2} bridging units as acceptor moieties. - Abstract: An efficient designing route to novel ternary copolymers consisting of polypyrrole (PPy), polythiophene (PTh) and polyfuran (PFu) is developed with the help of genetic algorithm. Using the band structure results obtained from ab initio crystal orbital (CO) calculations, the electronic structures and conduction properties of real ternary copolymers based on donor acceptor type polymers are investigated. The electron rich heterocyclic rings in the backbone chain of the copolymer are joined together by electron withdrawing groups Y, carbonyl group (>C=O) and difluoromethylene group (>C=CF{sub 2}) in an attempt to design the conducting polymer with lowest band gap. A comparative study of various electronic properties is presented. The effects of substitution on the behaviour and properties of the copolymers as well as on the density of states (DOS) are discussed. Band gap decreases as a result of substitution on the polymer backbone chain due to decrease in ionization potential and increase in electron affinity values. This is expected to enhance the intrinsic conductivity of the resulting copolymer. Use of alternate donor acceptor moieties within the repeat units should maximize the extended {pi} conjugation.

  20. J-V and C-V investigation of the effect of small molecular fullerene and non-fullerene acceptors for CH3NH3PbI3 perovskite solar cell

    Science.gov (United States)

    Zheng, Yanqiong; Wang, Chao; Yu, Junle; Yang, Fang; Zhang, Jing; Wei, Bin; Li, Weishi

    2017-11-01

    To find the ideal acceptors for perovskite solar cells (PSCs) and get insight into the dielectric property at the interface between perovskite and acceptor, series of small molecular fullerene and non-fullerene acceptors were comparatively investigated. Fullerene acceptors based PSCs show higher performance than non-fullerene acceptors based PSCs. However, the perylene tetracarboxylic diimide based PSC has achieved a η PCE of 4.70%, implying that it is a promising acceptor candidate for PSCs because of its suitable energy level, high electron mobility, and smooth surface. By employing double acceptors of (6,6)-phenyl-C61-butyric acid methyl ester (PCBM)/C60 or PCBM/3,4,9,10-perylenetetracarboxylic bisbenzimidazole, the PSC stability is greatly improved even without performance enhancement. The perovskite (Pero)/PCBM film shows smooth surface, suggesting that PCBM penetrates into the Pero layer. The hydrophobicity trend of Pero/acceptor composite films is same as the device performance by judging from the water contact angle, and Pero/PCBM as well as Pero/C60 show higher hydrophobicity than other Pero/small-molecular-acceptor composite films. Capacitance-voltage characteristics of the series of single and double acceptor based PSCs were measured. The double acceptor based PSCs show larger depletion layer width (W d) than single acceptor based PSCs. Meanwhile, the defect density (N A) in Pero layer for single acceptor based PSCs is larger than that for double acceptor based PSCs, implying better n-doping of Pero layer by using a single acceptor.

  1. Hole-transfer induced energy transfer in perylene diimide dyads with a donor-spacer-acceptor motif.

    Science.gov (United States)

    Kölle, Patrick; Pugliesi, Igor; Langhals, Heinz; Wilcken, Roland; Esterbauer, Andreas J; de Vivie-Riedle, Regina; Riedle, Eberhard

    2015-10-14

    We investigate the photoinduced dynamics of perylene diimide dyads based on a donor-spacer-acceptor motif with polyyne spacers of varying length by pump-probe spectroscopy, time resolved fluorescence, chemical variation and quantum chemistry. While the dyads with pyridine based polyyne spacers undergo energy transfer with near-unity quantum efficiency, in the dyads with phenyl based polyyne spacers the energy transfer efficiency drops below 50%. This suggests the presence of a competing electron transfer process from the spacer to the energy donor as the excitation sink. Transient absorption spectra, however, reveal that the spacer actually mediates the energy transfer dynamics. The ground state bleach features of the polyyne spacers appear due to the electron transfer decay with the same time constant present in the rise of the ground state bleach and stimulated emission of the perylene energy acceptor. Although the electron transfer process initially quenches the fluorescence of the donor it does not inhibit energy transfer to the perylene energy acceptor. The transient signatures reveal that electron and energy transfer processes are sequential and indicate that the donor-spacer electron transfer state itself is responsible for the energy transfer. Through the introduction of a Dexter blocker unit into the spacer we can clearly exclude any through bond Dexter-type energy transfer. Ab initio calculations on the donor-spacer and the donor-spacer-acceptor systems reveal the existence of a bright charge transfer state that is close in energy to the locally excited state of the acceptor. Multipole-multipole interactions between the bright charge transfer state and the acceptor state enable the energy transfer. We term this mechanism coupled hole-transfer FRET. These dyads represent a first example that shows how electron transfer can be connected to energy transfer for use in novel photovoltaic and optoelectronic devices.

  2. Photodouble ionization differential cross sections for D2 with various electron energy sharing conditions

    International Nuclear Information System (INIS)

    Seccombe, D.P.; Collins, S.A.; Reddish, T.J.; Selles, P.; Malegat, L.; Huetz, A.; Kazansky, A.K.

    2002-01-01

    The mutual angular distributions of the two ejected electrons following direct photodouble ionization have been measured for D 2 at an excess energy (E) of 25 eV using linearly polarized light. These (γ, 2e) 'triple' differential cross sections (TDCSs) were obtained for asymmetric electron energy conditions with energy sharing ratios (R=E 2 /E 1 ) of R=24, 11.5, 4 and 2.57. In all cases the 'reference' electron (energy = E 1 ) was oriented along the direction of the electric field vector (ε) and detected in coincidence with a second electron (energy = E 2 ) coplanar with ε and the photon beam direction (kγ). For comparison, helium TDCSs were obtained for the same E and R values under nearly identical spectrometer conditions. These show very good agreement with the results of hyperspherical-R-matrix with semi-classical outgoing waves calculations, thus providing even more confidence in the D 2 TDCSs where there is as yet no accurate ab initio theory. The similarities and differences between the experimental results associated with the two targets are qualitatively discussed in terms of Feagin's model (Feagin J M 1998 J. Phys. B: At. Mol. Opt. Phys. 31 L729). (author)

  3. Electronic and chemical properties of donor, acceptor centers in graphene

    Czech Academy of Sciences Publication Activity Database

    Telychko, Mykola; Mutombo, Pingo; Merino, P.; Hapala, Prokop; Ondráček, Martin; Bocquet, F.C.; Sforzini, J.; Stetsovych, Oleksandr; Vondráček, Martin; Jelínek, Pavel; Švec, Martin

    2015-01-01

    Roč. 9, č. 9 (2015), 9180-9187 ISSN 1936-0851 R&D Projects: GA ČR GA15-07172S; GA MŠk(CZ) LM2011029; GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : graphene * doping * AFM * STM * DFT * defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 13.334, year: 2015

  4. Spectroscopic Studies of the Electron Donor-Acceptor Interaction of ...

    African Journals Online (AJOL)

    Erah

    The objective of this study, therefore, was to develop an assay procedure for dosage forms of chloroquine phosphate based on its reaction with chloranilic acid which resulted in the formation of a charge-transfer complex. Methods: The complex formation between chloroquine phosphate and chloranilc acid as evidenced by.

  5. 78 FR 11555 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Design Roll Maneuver for Electronic...

    Science.gov (United States)

    2013-02-19

    ... Law 92-574, the ``Noise Control Act of 1972.'' The FAA issues special conditions, as defined in 14 CFR...; Design Roll Maneuver for Electronic Flight Controls AGENCY: Federal Aviation Administration (FAA), DOT... design roll maneuver for electronic flight controls, specifically an electronic flight control system...

  6. 77 FR 70384 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Design Roll Maneuver for Electronic...

    Science.gov (United States)

    2012-11-26

    ... Law 92-574, the ``Noise Control Act of 1972.'' The FAA issues special conditions, as defined in 14 CFR... Maneuver for Electronic Flight Controls AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... design roll maneuver for electronic flight controls, specifically an electronic flight control system...

  7. Quantum computing with acceptor spins in silicon.

    Science.gov (United States)

    Salfi, Joe; Tong, Mengyang; Rogge, Sven; Culcer, Dimitrie

    2016-06-17

    The states of a boron acceptor near a Si/SiO2 interface, which bind two low-energy Kramers pairs, have exceptional properties for encoding quantum information and, with the aid of strain, both heavy hole and light hole-based spin qubits can be designed. Whereas a light-hole spin qubit was introduced recently (arXiv:1508.04259), here we present analytical and numerical results proving that a heavy-hole spin qubit can be reliably initialised, rotated and entangled by electrical means alone. This is due to strong Rashba-like spin-orbit interaction terms enabled by the interface inversion asymmetry. Single qubit rotations rely on electric-dipole spin resonance (EDSR), which is strongly enhanced by interface-induced spin-orbit terms. Entanglement can be accomplished by Coulomb exchange, coupling to a resonator, or spin-orbit induced dipole-dipole interactions. By analysing the qubit sensitivity to charge noise, we demonstrate that interface-induced spin-orbit terms are responsible for sweet spots in the dephasing time [Formula: see text] as a function of the top gate electric field, which are close to maxima in the EDSR strength, where the EDSR gate has high fidelity. We show that both qubits can be described using the same starting Hamiltonian, and by comparing their properties we show that the complex interplay of bulk and interface-induced spin-orbit terms allows a high degree of electrical control and makes acceptors potential candidates for scalable quantum computation in Si.

  8. Ground-state thermodynamics of bistable redox-active donor-acceptor mechanically interlocked molecules.

    Science.gov (United States)

    Fahrenbach, Albert C; Bruns, Carson J; Cao, Dennis; Stoddart, J Fraser

    2012-09-18

    Fashioned through billions of years of evolution, biological molecular machines, such as ATP synthase, myosin, and kinesin, use the intricate relative motions of their components to drive some of life's most essential processes. Having control over the motions in molecules is imperative for life to function, and many chemists have designed, synthesized, and investigated artificial molecular systems that also express controllable motions within molecules. Using bistable mechanically interlocked molecules (MIMs), based on donor-acceptor recognition motifs, we have sought to imitate the sophisticated nanoscale machines present in living systems. In this Account, we analyze the thermodynamic characteristics of a series of redox-switchable [2]rotaxanes and [2]catenanes. Control and understanding of the relative intramolecular movements of components in MIMs have been vital in the development of a variety of applications of these compounds ranging from molecular electronic devices to drug delivery systems. These bistable donor-acceptor MIMs undergo redox-activated switching between two isomeric states. Under ambient conditions, the dominant translational isomer, the ground-state coconformation (GSCC), is in equilibrium with the less favored translational isomer, the metastable-state coconformation (MSCC). By manipulating the redox state of the recognition site associated with the GSCC, we can stimulate the relative movements of the components in these bistable MIMs. The thermodynamic parameters of model host-guest complexes provide a good starting point to rationalize the ratio of GSCC to MSCC at equilibrium. The bistable [2]rotaxanes show a strong correlation between the relative free energies of model complexes and the ground-state distribution constants (K(GS)). This relationship does not always hold for bistable [2]catenanes, most likely because of the additional steric and electronic constraints present when the two rings are mechanically interlocked with each other

  9. Charged dopants in neutral supercells through substitutional donor (acceptor): nitrogen donor charging of the nitrogen-vacancy center in diamond

    Science.gov (United States)

    Löfgren, Robin; Pawar, Ravinder; Öberg, Sven; Larsson, J. Andreas

    2018-02-01

    Charged defects are traditionally computed by adding (subtracting) electrons for negative (positive) impurities. When using periodic boundary conditions this results in artificially charged supercells that also require a compensating background charge of the opposite sign, which makes slab supercells problematic because of an arbitrary dependence on the vacuum thickness. In this work, we test the method of using neutral supercells through the use of a substitutional electron donor (acceptor) to describe charged systems. We use density functional theory (DFT) to compare the effects of charging the well-studied NV-center in diamond by a substitutional donor nitrogen. We investigate the influence of the donor-N on the NV-center properties as a function of the distance between them, and find that they converge toward those obtained when adding an electron. We analyze the spin density and conclude that the donor-N has a zero magnetic moment, and thus, will not be seen in electron spin resonance. We validate our DFT energies through comparison to GW simulations. Charging the NV-center with a substitutional donor-N enables accurate calculations of slabs, without the ambiguity of using charged supercells. Implantation of donor-N atoms opens up the possibility to engineer NV-centers with the desired charge state for future ICT and sensor applications.

  10. Donor-Acceptor Conjugated Macrocycles: Synthesis and Host-Guest Coassembly with Fullerene toward Photovoltaic Application.

    Science.gov (United States)

    Zhang, Si-Qi; Liu, Zhen-Yu; Fu, Wei-Fei; Liu, Feng; Wang, Chuan-Ming; Sheng, Chun-Qi; Wang, Yi-Fei; Deng, Ke; Zeng, Qing-Dao; Shu, Li-Jin; Wan, Jun-Hua; Chen, Hong-Zheng; Russell, Thomas P

    2017-11-28

    Electron-rich (donor) and electron-deficient (acceptor) units to construct donor-acceptor (D-A) conjugated macrocycles were investigated to elucidate their interactions with electron-deficient fullerene. Triphenylamine and 4,7-bisthienyl-2,1,3-benzothiadiazole were alternately linked through acetylene, as the donor and acceptor units, respectively, for pentagonal 3B2A and hexagonal 4B2A macrocycles. As detected by scanning tunneling microscopy, both D-A macrocycles were found to form an interesting concentration-controlled nanoporous monolayer on highly oriented pyrolytic graphite, which could effectively capture fullerene. Significantly, the fullerene filling was cavity-size-dependent with only one C 70 or PC 71 BM molecule accommodated by 3B2A, while two were accommodated by 4B2A. Density functional theory calculations were also utilized to gain insight into the host-guest systems and indicted that the S···π contact is responsible for stabilizing these host-guest systems. Owing to the ellipsoidal shape of C 70 , C 70 molecules are standing or lying in molecular cavities depending on the energy optimization. For the 3B2A/PC 71 BM blended film, PC 71 BM was intercalated into the cavity formed by the macrocycle 3B2A and provided excellent power conversion efficiency despite the broad band gap (2.1 eV) of 3B2A. This study of D-A macrocycles incorporating fullerene provides insights into the interaction mechanism and electronic structure in the host-guest complexes. More importantly, this is a representative example using D-A macrocycles as a donor to match with the spherical fullerene acceptor for photovoltaic applications, which offer a good approach to achieve molecular scale p-n junctions for substantially enhanced efficiencies of organic solar cells through replacing linear polymer donors by cyclic conjugated oligomers.

  11. Characteristics of energetic electron precipitation into the earth's polar atmosphere and geomagnetic conditions

    Science.gov (United States)

    Makhmutov, V. S.; Bazilevskaya, G. A.; Krainev, M. B.

    A number of energetic electron precipitation events (EPEs) were observed in the Earth's polar atmosphere (Murmansk region, geographical coordinates 68.57 N, 33.03 E and Mirny, Antarctica, 66.34 S, 92.55 E) during the long-term cosmic ray balloon experiment from 1957 up to now. During geomagnetic storms significant X-ray fluxes caused by precipitating electrons at the top of the atmosphere sometimes penetrated to the atmospheric depth of 60 gcm-2. We show that (1) there is a quasi-11-year cycle in EPE occurrence shifted with respect to solar activity cycle, and (2) the yearly rate of EPE occurrence has an ascending trend during the period 1965-1999. The EPE characteristics evaluated from the balloon experiment are compared with the available data on geomagnetic activity and the possible relations between the features of EPE events and geomagnetic conditions are discussed.

  12. Alkyl Radicals as Hydrogen Bond Acceptors: Computational Evidence

    DEFF Research Database (Denmark)

    Hammerum, Steen

    2009-01-01

    , and gives rise to pronounced shifts of IR stretching frequencies and to increased absorption intensities. The hydrogen bond acceptor properties of alkyl radicals equal those of many conventional acceptors, e.g., the bond length changes and IR red-shifts suggest that tert-butyl radicals are slightly better...

  13. Evaluation of Medipix2 detector for recording electron diffraction data in low dose conditions

    International Nuclear Information System (INIS)

    Georgieva, D; Sikharulidze, I; Jiang, L; Abrahams, J P; Jansen, J; Zandbergen, H W

    2011-01-01

    The drive for elucidation of important macromolecular structures to high resolution in their 3D native or near-native state places continuously higher demands on the quality of the experimental data. For instance, recording of diffraction patterns good enough for structural studies from cryo-preserved bio-macromolecules at low dose conditions remains challenging and highly desirable. The emergence of hybrid pixel detectors opens up new possibilities for direct electron detection and superior detector performance. Here, we report on the characteristics of the Medipix2 detector in diffraction studies, with a special focus on the reliability of the intensities acquired in very low dose conditions. Diffraction data recorded on a Medipix2 detector were assessed in refinement analysis. R-factors lower than 10% were obtained from data recorded at electron dose of 0.05 el/A 2 . The reproducibility of the data was also shown to be high, given the correlation coefficient of the intensities being higher than 0.9970. The contrast that could be achieved at very low dose conditions was at least an order of magnitude better than that of image plates, based on a direct comparison.

  14. Architecture of the upgraded BCM1F backend electronics for Beam Conditions and Luminosity measurement

    Science.gov (United States)

    Zagozdzinska, A. A.; Dabrowski, A. E.; Przyborowski, D.; Leonard, J. L.; Pozniak, K. T.; Miraglia, M.; Walsh, R.; Lange, W.; Lohmann, W.; Ryjov, V.

    2015-02-01

    The Beam Radiation Instrumentation and Luminosity Project of the CMS experiment consists of several beam monitoring systems and luminometers. The upgraded Fast Beam Conditions Monitor is based on 24 single crystal diamond sensors with a two-pad metallization and a custom designed readout. Signals for real time monitoring are transmitted to the counting room, where they are received and processed by new back-end electronics designed to measure count rates on LHC collision, beam induced background and activation products to be used to determine the luminosity and the machine induced background. The system architecture and the signal processing algorithms will be presented.

  15. Choice of the best use conditions of the scanning electron microscope

    International Nuclear Information System (INIS)

    Dubus, A.

    1985-01-01

    Suggestions are given to the user to allow him a best control of the scanning electron microscope operation, and to fit, in the best way, the operation conditions in front of the specificity of each problem. The user is recalled the need of best knowledge control of the nature of the sample, the type of researched information (at what scale, what accuracy,...). The user is given the principal criterions of choice to deduce, in function of the technique physical parameters, a compromise in the operation parameters [fr

  16. Barbiturate end-capped non-fullerene acceptors for organic solar cells: tuning acceptor energetics to suppress geminate recombination losses.

    Science.gov (United States)

    Tan, Ching-Hong; Gorman, Jeffrey; Wadsworth, Andrew; Holliday, Sarah; Subramaniyan, Selvam; Jenekhe, Samson A; Baran, Derya; McCulloch, Iain; Durrant, James R

    2018-01-26

    We report the synthesis of two barbiturate end-capped non-fullerene acceptors and demonstrate their efficient function in high voltage output organic solar cells. The acceptor with the lower LUMO level is shown to exhibit suppressed geminate recombination losses, resulting in enhanced photocurrent generation and higher overall device efficiency.

  17. Barbiturate End-Capped Non-Fullerene Acceptors for Organic Solar Cells: Tuning Acceptor Energetics to Suppress Geminate Recombination Losses

    KAUST Repository

    Tan, Ching-Hong

    2018-01-10

    We report the synthesis of two barbiturate end-capped non-fullerene acceptors and demonstrate their efficient function in high voltage output organic solar cells. The acceptor with the lower LUMO level is shown to exhibit suppressed geminate recombination losses, resulting in enhanced photocurrent generation and higher overall device efficiency.

  18. Influence of Experimental Conditions on Electronic Tongue Results—Case of Valsartan Minitablets Dissolution

    Directory of Open Access Journals (Sweden)

    Małgorzata Wesoły

    2016-08-01

    Full Text Available A potentiometric electronic tongue was applied to study the release of valsartan from pharmaceutical formulations, i.e., minitablets uncoated and coated with Eudragit E. Special attention was paid to evaluate the influence of medium temperature and composition, as well as to compare the performances of the sensor arrays working in various hydrodynamic conditions. The drug dissolution profiles registered with the ion-sensitive electrodes were compared with standard dissolution tests performed with USP Apparatus 2 (paddle. Moreover, the signal changes of all sensors were processed by principal component analysis to visualize the release modifications, related to the presence of the coating agent. Finally, the importance and influence of the experimental conditions on the results obtained using potentiometric sensor arrays were discussed.

  19. Purification and properties of NAD(P)H: (quinone-acceptor) oxidoreductase of sugarbeet cells.

    Science.gov (United States)

    Trost, P; Bonora, P; Scagliarini, S; Pupillo, P

    1995-12-01

    NAD(P)H:(quinone-acceptor) oxidoreductase [NAD(P)H-QR], a plant cytosolic protein, was purified from cultured sugarbeet cells by a combination of ammonium sulfate fractionation, FPLC Superdex 200 gel filtration, Q-Sepharose anion-exchange chromatography, and a final Blue Sepharose CL-6B affinity chromatography with an NADPH gradient. The subunit molecular mass is 24 kDa and the active protein (94 kDa) is a tetramer. The isoelectric point is 4.9. The enzyme was characterized by ping-pong kinetics and extremely elevated catalytic capacity. It prefers NADPH over NADH as electron donor (kcat/Km ratios of 1.7 x 10(8) M-1 S-1 and 8.3 x 10(7) M-1 S-1 for NADPH and NADH, respectively, with benzoquinone as electron acceptor). The acridone derivative 7-iodo-acridone-4-carboxylic acid is an efficient inhibitor (I0.5 = 5 x 10(-5) M), dicumarol is weakly inhibitory. The best acceptor substances are hydrophilic, short-chain quinones such as ubiquinone-0 (Q-0), benzoquinone and menadione, followed by duroquinone and ferricyanide, whereas hydrophobic quinones, cytochrome c and oxygen are reduced at negligible rates at best. Quinone acceptors are reduced by a two-electron reaction with no apparent release of free semiquinonic intermediates. This and the above properties suggest some relationship of NAD(P)H-QR to DT-diaphorase, an animal flavoprotein which, however, has distinct structural properties and is strongly inhibited by dicumarol. It is proposed that NAD(P)H-QR by scavenging unreduced quinones and making them prone to conjugation may act in plant tissues as a functional equivalent of DT-diaphorase.

  20. Measuring drug saturation solubility in thin polymer films: use of a thin acceptor layer.

    Science.gov (United States)

    Kunst, Anders; Lee, Geoffrey

    2015-03-15

    The saturation solubility of scopolamine base in two pressure sensitive adhesive DURO-TAKs has been determined using the 5-layer laminate technique. The acceptor layer had a thickness of less than 25 μm to promote a rapid partitioning equilibrium. With DURO-TAK 87-2510 the saturation solubility is 5.2 ± 0.6% w/w when measured after 7 days. With DURO-TAK 87-4098 the saturation solubility is slightly higher, 7.9 ± 0.7% w/w after 7 days. These values remained constant up to approximately 30 days' experimental time. In both cases the acceptor was free of crystalline material at the end of the experiment. This strongly suggests that that equilibrium had been reached between the saturated solution in the acceptor layer and the crystalline drug still present in the donor layer. The addition of light liquid paraffin to the acceptor produced a solubilizing effect with 87-4098 but not 87-2510. We recommend some experimental conditions that we consider to be necessary to achieve a reliable and accurate result with this technique. If performed correctly, it can give a feasible result. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Impact of Organic Carbon Electron Donors on Microbial Community Development under Iron- and Sulfate-Reducing Conditions.

    Directory of Open Access Journals (Sweden)

    Man Jae Kwon

    Full Text Available Although iron- and sulfate-reducing bacteria in subsurface environments have crucial roles in biogeochemical cycling of C, Fe, and S, how specific electron donors impact the compositional structure and activity of native iron- and/or sulfate-reducing communities is largely unknown. To understand this better, we created bicarbonate-buffered batch systems in duplicate with three different electron donors (acetate, lactate, or glucose paired with ferrihydrite and sulfate as the electron acceptors and inoculated them with subsurface sediment as the microbial inoculum. Sulfate and ferrihydrite reduction occurred simultaneously and were faster with lactate than with acetate. 16S rRNA-based sequence analysis of the communities over time revealed that Desulfotomaculum was the major driver for sulfate reduction coupled with propionate oxidation in lactate-amended incubations. The reduction of sulfate resulted in sulfide production and subsequent abiotic reduction of ferrihydrite. In contrast, glucose promoted faster reduction of ferrihydrite, but without reduction of sulfate. Interestingly, the glucose-amended incubations led to two different biogeochemical trajectories among replicate bottles that resulted in distinct coloration (white and brown. The two outcomes in geochemical evolution might be due to the stochastic evolution of the microbial communities or subtle differences in the initial composition of the fermenting microbial community and its development via the use of different glucose fermentation pathways available within the community. Synchrotron-based x-ray analysis indicated that siderite and amorphous Fe(II were formed in the replicate bottles with glucose, while ferrous sulfide and vivianite were formed with lactate or acetate. These data sets reveal that use of different C utilization pathways projects significant changes in microbial community composition over time that uniquely impact both the geochemistry and mineralogy of subsurface

  2. Low-energy-electron interactions with DNA: approaching cellular conditions with atmospheric experiments

    International Nuclear Information System (INIS)

    Alizadeh, E.; Sanche, L.

    2014-01-01

    A novel technique has been developed to investigate low energy electron (LEE)-DNA interactions in the presence of small biomolecules (e.g., N 2 , O 2 , H 2 O) found near DNA in the cell nucleus, in order to simulate cellular conditions. In this technique, LEEs are emitted from a metallic surface exposed by soft X-rays and interact with DNA thin films at standard ambient temperature and pressure (SATP). Whereas atmospheric N 2 had little effect on the yields of LEE-induced single and double strand breaks, both O 2 and H 2 O considerably modified and increased such damage. The highest yields were obtained when DNA is embedded in a combined O 2 and H 2 O atmosphere. In this case, the amount of additional double strand breaks was supper-additive. The effect of modifying the chemical and physical stability of DNA by platinum-based chemotherapeutic agents (Pt-drugs) including cisplatin, carboplatin and oxaliplatin was also investigated with this technique. The results obtained provide information on the role played by subexcitation-energy electrons and dissociative electron attachment in the radiosensitization of DNA by Pt-drugs, which is an important step to unravel the mechanisms of radiosensitization of these agents in chemo-radiation cancer therapy. (authors)

  3. Low-energy-electron interactions with DNA: approaching cellular conditions with atmospheric experiments

    Science.gov (United States)

    Alizadeh, Elahe; Sanche, Léon

    2014-04-01

    A novel technique has been developed to investigate low energy electron (LEE)-DNA interactions in the presence of small biomolecules (e.g., N2, O2, H2O) found near DNA in the cell nucleus, in order to simulate cellular conditions. In this technique, LEEs are emitted from a metallic surface exposed by soft X-rays and interact with DNA thin films at standard ambient temperature and pressure (SATP). Whereas atmospheric N2 had little effect on the yields of LEE-induced single and double strand breaks, both O2 and H2O considerably modified and increased such damage. The highest yields were obtained when DNA is embedded in a combined O2 and H2O atmosphere. In this case, the amount of additional double strand breaks was supper-additive. The effect of modifying the chemical and physical stability of DNA by platinum-based chemotherapeutic agents (Pt-drugs) including cisplatin, carboplatin and oxaliplatin was also investigated with this technique. The results obtained provide information on the role played by subexcitation-energy electrons and dissociative electron attachment in the radiosensitization of DNA by Pt-drugs, which is an important step to unravel the mechanisms of radiosensitisation of these agents in chemoradiation cancer therapy.

  4. The experimental electron mean-free-path in Si under typical (S)TEM conditions

    International Nuclear Information System (INIS)

    Potapov, P.L.

    2014-01-01

    The electron mean-free-path in Si was measured by EELS using the test structure with the certified dimensions as a calibration standard. In a good agreement with the previous CBED measurements, the mean-free-path is 150 nm for 200 keV and 179 nm for 300 keV energy of primary electrons at large collection angles. These values are accurately predicted by the model of Iakoubovskii et al. while the model of Malis et al. incorporated in common microscopy software underestimates the mean-free-path by 15% at least. Correspondingly, the thickness of TEM samples reported in many studies of the Si-based materials last decades might be noticeably underestimated. - Highlights: • The electron inelastic mean-free-path in Si is measured for the typical (S)TEM conditions. • These reference values allow for accurate determination of the lamella thickness by EELS. • The theoretical model by Malis et al. underestimates the mean-free-path values

  5. Using Electronic Health Record Data to Measure Care Quality for Individuals with Multiple Chronic Medical Conditions.

    Science.gov (United States)

    Bayliss, Elizabeth A; McQuillan, Deanna B; Ellis, Jennifer L; Maciejewski, Matthew L; Zeng, Chan; Barton, Mary B; Boyd, Cynthia M; Fortin, Martin; Ling, Shari M; Tai-Seale, Ming; Ralston, James D; Ritchie, Christine S; Zulman, Donna M

    2016-09-01

    To inform the development of a data-driven measure of quality care for individuals with multiple chronic conditions (MCCs) derived from an electronic health record (EHR). Qualitative study using focus groups, interactive webinars, and a modified Delphi process. Research department within an integrated delivery system. The webinars and Delphi process included 17 experts in clinical geriatrics and primary care, health policy, quality assessment, health technology, and health system operations. The focus group included 10 individuals aged 70-87 with three to six chronic conditions selected from a random sample of individuals aged 65 and older with three or more chronic medical conditions. Through webinars and the focus group, input was solicited on constructs representing high-quality care for individuals with MCCs. A working list was created of potential measures representing these constructs. Using a modified Delphi process, experts rated the importance of each possible measure and the feasibility of implementing each measure using EHR data. High-priority constructs reflected processes rather than outcomes of care. High-priority constructs that were potentially feasible to measure included assessing physical function, depression screening, medication reconciliation, annual influenza vaccination, outreach after hospital admission, and documented advance directives. High-priority constructs that were less feasible to measure included goal setting and shared decision-making, identifying drug-drug interactions, assessing social support, timely communication with patients, and other aspects of good customer service. Lower-priority domains included pain assessment, continuity of care, and overuse of screening or laboratory testing. High-quality MCC care should be measured using meaningful process measures rather than outcomes. Although some care processes are currently extractable from electronic data, capturing others will require adapting and applying technology to

  6. Optical properties of metastable shallow acceptors in Mg-doped GaN layers grown by metal-organic vapor phase epitaxy

    OpenAIRE

    Pozina, Galia; Hemmingsson, Carl; Bergman, Peder; Kawashima, T.; Amano, H.; Akasaki, I.; Usui, A.; Monemar, Bo

    2010-01-01

    GaN layers doped by Mg show a metastable behavior of the near-band-gap luminescence caused by electron irradiation or UV excitation. At low temperatures < 30 K the changes in luminescence are permanent. Heating to room temperature recovers the initial low temperature spectrum shape completely. Two acceptors are involved in the recombination process as confirmed by transient PL. In as-grown samples a possible candidate for the metastable acceptor is C-N, while after annealing a second m...

  7. Comparative evaluation of the acceptor properties of quinone derivatized polypyridinic ligands

    Energy Technology Data Exchange (ETDEWEB)

    Norambuena, Ester [Departamento de Quimica, Facultad de Ciencias Basicas, Universidad Metropolitana de Ciencias de la Educacion, Santiago (Chile); Olea-Azar, Claudio [Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chile, Santiago (Chile); Delgadillo, Alvaro [Departamento de Quimica, Facultad de Ciencias, Universidad de La Serena, Casilla 599, La Serena (Chile); Barrera, Mauricio [Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile); Loeb, Barbara, E-mail: bloeb@puc.cl [Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile)

    2009-05-18

    The reduction properties of four acceptor polipyridyl ligands modified with quinones were studied by different experimental methods, as cyclic voltammetry and ESR spectroscopy, and by theoretical calculations. ESR spectra for the reduced ligands show different patterns among them, suggesting that the quinone moiety plays an important role in the delocalization of the received electron. The hyperfine coupling constants calculated for the magnetic nucleus were in good agreement with experimental data. The results were additionally interpreted with the help of two theoretical predictors: the electrophilicity index and the Fukui function obtained through the spin density. The results suggest that 12,17-dihydronaphtho-[2,3-h]dipyrido[3,2-a:2',3'-c]-phenazine-12,17-dione, Aqphen, shows the most promising behavior to be employed as an acceptor ligand in complexes with potential application in NLO devices.

  8. Organic solar cells based on anthracene-containing PPE–PPVs and non-fullerene acceptors

    KAUST Repository

    Alam, Shahidul

    2018-04-13

    Lately, non-fullerene acceptors (NFAs) have received increasing attention for use in polymer-based bulk-heterojunction (BHJ) organic solar cells (OSCs), as improved photovoltaic performance compared to classical polymer–fullerene blends could be demonstrated. In this study, polymer solar cells based on a statistically substituted anthracene-containing poly(p-phenylene ethynylene)-alt-poly(p-phenylene vinylene)s (PPE–PPVs) copolymer (AnE-PVstat) as donor in combination with a number of different electron accepting materials were investigated. Strong photoluminescence quenching of the polymer donor indicates intimate intermixing of both materials. However, the photovoltaic performances were found to be poor compared to blends that use fullerene as acceptor. Time-delayed collection field (TDCF) measurements demonstrate: charge generation is field-independent, but bimolecular recombination processes limit the fill factor and thus the efficiency of devices.

  9. All-Polymer Solar Cells Based on Fully Conjugated Donor-Acceptor Block Copolymers with Poly(naphthalene bisimide Acceptor Blocks: Device Performance and Thin Film Morphology

    Directory of Open Access Journals (Sweden)

    Kazuhiro Nakabayashi

    2015-01-01

    Full Text Available All-polymer solar cells are fabricated by using poly(3-hexylthiophene (P3HT and fully conjugated donor-acceptor (D-A block copolymer (P3HT-PNBI-P3HT as donor and acceptor materials, respectively. Atomic force microscopy (AFM and grazing incidence wide angle X-ray scattering (GIWAXS analyses reveal that device performance strongly depends on the P3HT:P3HT-PNBI-P3HT thin film morphology. Indeed, the π-π stacking nanomorphology rich in the edge-on orientation is formed in the P3HT:P3HT-PNBI-P3HT thin film by optimizing the fabrication conditions, for example, thermal annealing temperature and cast solvent. Consequently, the power conversion efficiency (PCE of 1.60% is achieved with an open-circuit voltage (Voc of 0.59 V, short-current (Jsc of 4.43 mA/cm2, and fill factor (FF of 0.61. These results suggest that P3HT-PNBI-P3HT has the huge potential for the usage as a nonfullerene acceptor material.

  10. Synthesis of Donor-Acceptor Conjugated Polymers by "CLICK" Polymerization for OPV applications

    DEFF Research Database (Denmark)

    Brandt, Rasmus Guldbæk; Yu, Donghong

    The intent of this study was to utilize the Copper(I)-catalyzed Azide Alkyne Cycloaddition (CuAAC) as a polymerization technique (“Click” Polymerization) for synthesizing novel π-conjugated low band gap polymers for organic photovoltaic applications (OPV). The chosen approach was to synthesize...... an alternating electron donating (donor, D) and electron withdrawing (acceptor, A) co-polymer. The chosen monomers were well known units, and the novelty lies in using the monomer units with the click methodology. An insoluble alternating copolymer consisting of 2,7-diazido-9,9-dioctyl-9Hflourene and 1...

  11. π-Bridge-Independent 2-(Benzo[c][1,2,5]thiadiazol-4-ylmethylene)malononitrile-Substituted Nonfullerene Acceptors for Efficient Solar Cells

    KAUST Repository

    Wang, Kai

    2016-02-25

    Molecular acceptors are promising alternatives to fullerenes (e.g. PC61/71BM) in the fabrication of high-efficiency bulk-heterojunction (BHJ) solar cells. While solution-processed polymer-fullerene BHJ devices have recently met the 10% efficiency threshold, molecular acceptors have yet to prove comparably efficient with polymer donors. At this point in time, it is important to forge a better understanding of the design parameters that directly impact small-molecule (SM) acceptor performance in BHJ solar cells. In this report, we show that 2-(benzo[c][1,2,5]thiadiazol-4-ylmethylene)malononitrile (BM)-terminated SM acceptors can achieve efficiencies as high as 5.3% in BHJ solar cells with the polymer donor PCE10. Through systematic device optimization and characterization studies, we find that the nonfull-erene analogues (FBM, CBM and CDTBM) all perform comparably well, independent of the molecular structure and electronics of the π-bridge that links the two electron-deficient BM end groups. With estimated electron affinities within range of those of common fullerenes (4.0-4.3 eV), and a wider range of ionization potentials (6.2-5.6 eV), the SM acceptors absorb in the visible spectrum and effectively contribute to the BHJ device photocurrent. BM-substituted SM acceptors are promising alterna-tives to fullerenes in solution-processed BHJ solar cells.

  12. The study of optimal conditions of electrochemical etching of tunnel electron microscopy tungsten tips

    International Nuclear Information System (INIS)

    Anguiano, E.; Aguilar, M.; Olivar, A.I.

    1996-01-01

    We present the experimental results obtained during the study made in the electrochemical etching of tunneling electron microscopy tungsten tips. The experiments was made using DC and two usual electrolytes: KOH and NaOH. For the tip preparation we used a electrochemical cell with stainless steel cathode and the tungsten wire as anode. the electrodes was introduced in a glass recipient containing the electrolytic solution. We study the effects of applied voltage, polish time, tip length and electrolyte concentration as process relevant parameters. The best condition for tip preparation was obtained with a metallurgical microscope and with a SEM.EDX and Auger analysis was made. The results shown the better tips was made with KOH as electrolyte with a limited concentration range (2-4 normal) and applied voltage (2-6 volts) (Author) 20 refs

  13. Proton-coupled electron transfer promotes the reduction of ferrylmyoglobin by uric acid under physiological conditions

    DEFF Research Database (Denmark)

    de Zawadzki, Andressa; Cardoso, Daniel R.; Skibsted, Leif Horsfelt

    2017-01-01

    The hypervalent muscle pigment ferrylmyoglobin, MbFe(IV)]O, is not reduced by urate monoanions at physiological conditions despite a strong driving force of around 30 kJ mol1 while for low pH, uric acid was found to reduce protonated ferrylmyoglobin, MbFe(IV)]O,H+, efficiently in a bimolecular...... reaction with k1 ¼ 1.1 0.1 103 L mol1 s1, DH‡ ¼ 66.1 0.1 kJ mol1 and DS‡ ¼ 35.2 0.2 J mol1 K1. For intermediate pH, like for anaerobic muscles and for meat, proton-oupled electron transfer occurs in a transition state, {MbFe(IV)]O/H+/urate}‡, which is concluded to be formed from uric acid and Mb...... in uric acid concentration may serve as an inherent protection against radical formation by ferrylmyoglobin...

  14. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    Science.gov (United States)

    Lobato, I.; Rojas, J.; Landauro, C. V.; Torres, J.

    2009-02-01

    The structural evolution and dynamics of silver nanodrops Ag2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 × 1013 K s-1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 × 1012 K s-1), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  15. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    International Nuclear Information System (INIS)

    Lobato, I; Rojas, J; Landauro, C V; Torres, J

    2009-01-01

    The structural evolution and dynamics of silver nanodrops Ag 2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 x 10 13 K s -1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 x 10 12 K s -1 ), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  16. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, I; Rojas, J [Instituto Peruano de EnergIa Nuclear, Avenida Canada 1470, Lima 41 (Peru); Landauro, C V; Torres, J [Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, P.O. box 14-0149, Lima 14 (Peru)], E-mail: jrojast@unmsm.edu.pe

    2009-02-04

    The structural evolution and dynamics of silver nanodrops Ag{sub 2869} (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 x 10{sup 13} K s{sup -1} the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 x 10{sup 12} K s{sup -1}), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  17. An Opto-Electronic Sensor for Detecting Soil Microarthropods and Estimating Their Size in Field Conditions

    Directory of Open Access Journals (Sweden)

    Csongor I. Gedeon

    2017-08-01

    Full Text Available Methods to estimate density of soil-dwelling arthropods efficiently, accurately and continuously are critical for investigating soil biological activity and evaluating soil management practices. Soil-dwelling arthropods are currently monitored manually. This method is invasive, and time- and labor-consuming. Here we describe an infrared opto-electronic sensor for detection of soil microarthropods in the size range of 0.4–10 mm. The sensor is built in a novel microarthropod trap designed for field conditions. It allows automated, on-line, in situ detection and body length estimation of soil microarthropods. In the opto-electronic sensor the light source is an infrared LED. Two plano-convex optical lenses are placed along the virtual optical axis. One lens on the receiver side is placed between the observation space at 0.5–1 times its focal length from the sensor, and another emitter side lens is placed between the observation space and the light source in the same way. This paper describes the setup and operating mechanism of the sensor and the control unit, and through basic tests it demonstrates its potential in automated detection of soil microarthropods. The sensor may be used for monitoring activities, especially for remote observation activities in soil and insect ecology or pest control.

  18. Development and validation of a continuous measure of patient condition using the Electronic Medical Record.

    Science.gov (United States)

    Rothman, Michael J; Rothman, Steven I; Beals, Joseph

    2013-10-01

    Patient condition is a key element in communication between clinicians. However, there is no generally accepted definition of patient condition that is independent of diagnosis and that spans acuity levels. We report the development and validation of a continuous measure of general patient condition that is independent of diagnosis, and that can be used for medical-surgical as well as critical care patients. A survey of Electronic Medical Record data identified common, frequently collected non-static candidate variables as the basis for a general, continuously updated patient condition score. We used a new methodology to estimate in-hospital risk associated with each of these variables. A risk function for each candidate input was computed by comparing the final pre-discharge measurements with 1-year post-discharge mortality. Step-wise logistic regression of the variables against 1-year mortality was used to determine the importance of each variable. The final set of selected variables consisted of 26 clinical measurements from four categories: nursing assessments, vital signs, laboratory results and cardiac rhythms. We then constructed a heuristic model quantifying patient condition (overall risk) by summing the single-variable risks. The model's validity was assessed against outcomes from 170,000 medical-surgical and critical care patients, using data from three US hospitals. Outcome validation across hospitals yields an area under the receiver operating characteristic curve(AUC) of ≥0.92 when separating hospice/deceased from all other discharge categories, an AUC of ≥0.93 when predicting 24-h mortality and an AUC of 0.62 when predicting 30-day readmissions. Correspondence with outcomes reflective of patient condition across the acuity spectrum indicates utility in both medical-surgical units and critical care units. The model output, which we call the Rothman Index, may provide clinicians with a longitudinal view of patient condition to help address known

  19. Electronic apex locator: A comprehensive literature review — Part II: Effect of different clinical and technical conditions on electronic apex locator′s accuracy

    Directory of Open Access Journals (Sweden)

    Hamid Razavian

    2014-01-01

    Full Text Available Introduction: To investigate the effects of different clinical and technical conditions on the accuracy of electronic apex locators (EALs. Materials and Methods: "Tooth apex," "dental instrument," "odontometry," "electronic medical," and "electronic apex locator" were searched as primary identifiers via Medline/PubMed, Cochrane library, and Scopus data base up to 30 July 2013. Original articles that fulfilled the inclusion criteria were selected and reviewed. Results: Out of 402 relevant studies, 183 were selected based on the inclusion criteria. In this part, 75 studies are presented. Pulp vitality conditions and root resorption, types of files and irrigating materials do not affect an EAL′s accuracy; however, the file size and foramen diameter can affect its accuracy. Conclusions: Various clinical conditions such as the file size and foramen diameter may affect EALs′ accuracy. However, more randomized clinical trials are needed for definitive conclusion.

  20. Comparing the Device Physics and Morphology of Polymer Solar Cells Employing Fullerenes and Non-Fullerene Acceptors

    KAUST Repository

    Bloking, Jason T.

    2014-04-23

    There is a need to find electron acceptors for organic photovoltaics that are not based on fullerene derivatives since fullerenes have a small band gap that limits the open-circuit voltage (VOC), do not absorb strongly and are expensive. Here, a phenylimide-based acceptor molecule, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (HPI-BT), that can be used to make solar cells with VOC values up to 1.11 V and power conversion efficiencies up to 3.7% with two thiophene polymers is demonstrated. An internal quantum efficiency of 56%, compared to 75-90% for polymer-fullerene devices, results from less efficient separation of geminate charge pairs. While favorable energetic offsets in the polymer-fullerene devices due to the formation of a disordered mixed phase are thought to improve charge separation, the low miscibility (<5 wt%) of HPI-BT in polymers is hypothesized to prevent the mixed phase and energetic offsets from forming, thus reducing the driving force for charges to separate into the pure donor and acceptor phases where they can be collected. A small molecule electron acceptor, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (HPI-BT), achieves efficiencies of 3.7% and open-circuit voltage values of 1.11 V in bulk heterojunction (BHJ) devices with polythiophene donor materials. The lower internal quantum efficiency (56%) in these non-fullerene acceptor devices is attributed to an absence of the favorable energetic offsets resulting from nanoscale mixing of donor and acceptor found in comparable fullerene-based devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2002-01-01

    We present a new view and an analytical formalism of electron flow through a donor-acceptor molecule inserted between a pair of metal electrodes. The donor and acceptor levels are strongly coupled to an environmental nuclear continuum. The formalism applies to molecular donor-acceptor systems both...... in vacuum or air, and in aqueous solution under electrochemical potential control. Multifarious patterns of rectified electron flow from the negatively to the positively biased electrode arise. The electronic interaction between the donor and acceptor fragments, mutually and with the electrodes, can be weak...

  2. Synthesis on power electronics for large fuel cells: From power conditioning to potentiodynamic analysis technique

    International Nuclear Information System (INIS)

    De Bernardinis, Alexandre

    2014-01-01

    Highlights: • Active load for fuel cell managing electrical drive constraints: frequency and current ripple can be adjusted independently. • Multi-port resonant soft-switched topology for power management of a thirty kilowatt segmented PEM fuel cell. • Splitting current control strategy for power segmented PEM fuel cell in case of a segment is under fault. • Reversible Buck topology for large fuel cell with control of the fuel cell potential linked to current density nonlinearity. - Abstract: The work addressed in this paper deals with a synthesis on power electronic converters used for fuel cells. The knowledge gap concerns conceptually different electronic converter architectures for PEM (Proton Exchange Membrane) fuel cells able to perform three types of functionalities: The first one is the capacity of emulating an active load representative of electrical drive constraints. In that case, frequency and fuel cell current ripple can be set independently to investigate the dynamic behavior of the fuel cell. The second one is power conditioning applied to large high power and segmented fuel cell systems (“Large” represents several tens of cells and multi-kilowatt stacks), which is a non trivial consideration regarding the topological choices to be made for improving efficiency, compactness and ensure operation under faulty condition. A multi-port resonant isolated boost topology is analyzed enabling soft switching over a large operating range for a thirty kilowatt segmented fuel cell. A splitting current control strategy in case of a segment is under fault is proposed. Each considered converter topologies meet specific constraints regarding fuel cell stack design and power level. The third functionality is the ability for the power electronics to perform analysis and diagnosis techniques, like the cyclic voltammetry on large PEM fuel cell assemblies. The latter technique is an uncommon process for large fuel cell stacks since it is rather performed on

  3. Tracking Electron Uptake from a Cathode into Shewanella Cells: Implications for Energy Acquisition from Solid-Substrate Electron Donors

    Directory of Open Access Journals (Sweden)

    Annette R. Rowe

    2018-02-01

    Full Text Available While typically investigated as a microorganism capable of extracellular electron transfer to minerals or anodes, Shewanella oneidensis MR-1 can also facilitate electron flow from a cathode to terminal electron acceptors, such as fumarate or oxygen, thereby providing a model system for a process that has significant environmental and technological implications. This work demonstrates that cathodic electrons enter the electron transport chain of S. oneidensis when oxygen is used as the terminal electron acceptor. The effect of electron transport chain inhibitors suggested that a proton gradient is generated during cathode oxidation, consistent with the higher cellular ATP levels measured in cathode-respiring cells than in controls. Cathode oxidation also correlated with an increase in the cellular redox (NADH/FMNH2 pool determined with a bioluminescence assay, a proton uncoupler, and a mutant of proton-pumping NADH oxidase complex I. This work suggested that the generation of NADH/FMNH2 under cathodic conditions was linked to reverse electron flow mediated by complex I. A decrease in cathodic electron uptake was observed in various mutant strains, including those lacking the extracellular electron transfer components necessary for anodic-current generation. While no cell growth was observed under these conditions, here we show that cathode oxidation is linked to cellular energy acquisition, resulting in a quantifiable reduction in the cellular decay rate. This work highlights a potential mechanism for cell survival and/or persistence on cathodes, which might extend to environments where growth and division are severely limited.

  4. Influence of gas conditions on electron temperature inside a pinch column of plasma-focus discharge

    Science.gov (United States)

    Zaloga, D. R.; Sadowski, M. J.; Skladnik-Sadowska, E.; Paduch, M.; Zielinska, E.; Tomaszewski, K.

    2018-01-01

    The paper reports on soft x-ray emission from high-current discharges in PF-1000U facility operated at 170 kJ. The discharges at static conditions were performed with pure deuterium (D2) and a mixture of D2 and neon (Ne). In shots with the gas-puffing 1 cm3 of D2 or a (D2+Ne) mixture was injected 2 ms before the discharge initiation. Time-integrated x-ray images from a Be-filtered pinhole camera showed that the pinch microstructure depends strongly on gas conditions. In shots with the D2-, (D2+Ne)- or He-puffing distinct “filaments” and “hot-spots” were observed. Time-resolved x-ray pulses were recorded with 4 filtered PIN-diodes which recorded signals from 2 regions of 3 cm in diameter (at z = 3 cm and 6 cm from the anode). From a ratio of x-ray pulses, measured behind different filters, it was estimated that at the static D2-filling electron temperatures (Te ) were from 90 eV to 200 eV. At the D2-filling and -puffing additional x-ray spikes were emitted from “hot-spots” with Te twice higher. In shots at the (D2+10%Ne)-filling Te was 4 keV. In shots with the (D2+Ne)-mixture puffing intense “hot-spots” were formed, and Te reached 2.2-7.5 keV. At the same conditions “filaments” were reproducible macroscopically, but “hot-spots” were irreproducible.

  5. Evaluation of Fibrin Clot Attachment on Titanium Laser-Conditioned Surface Using Scanning Electron Microscopy.

    Science.gov (United States)

    Sinjari, Bruna; Traini, Tonino; Caputi, Sergio; Mortellaro, Carmen; Scarano, Antonio

    2018-03-22

    The study aimed to evaluate the effects of different titanium surface treatments on blood clot extension (bce). A total of 54 titanium disks with machined surface (M), laser-conditioned surface (L), and grit-blasted surface (S) were used in the present study. The surface characteristics such as contact angles and the microroughness were determined on each group (n = 4). To evaluate the bce, 0.1 mL of human blood was dropped onto the surface of each specimen and left for 7 minutes at room temperature. After fixation, dehydration, and gold sputtering treatments, the specimens were observed under scanning electron microscope. The bce values were expressed as percentage of specimen surface covered by blood clot. The surface roughness (Ra ± standard deviation [SD]) was 0.75 ± 0.02 μm for M, 0.25 ± 0.02 μm for L, and 1.30 ± 0.03 μm for S. The contact angles measured in static conditions (WCA ± SD) were 71 ± 5.4° for M, 107 ± 6.6° for L, and 91 ± 7.2° for S. Regarding the bce (bce ± SD) of M samples (65.5 ± 4.3%) was statistically lower compared with both L (83.4 ± 5.1%) and S samples (72.4 ± 4.7%) (P < 0.05). Meanwhile, the L group showed the higher bce value. The present results suggest that the laser-conditioned surface may increase the wettability and bce.

  6. Use of Electronic Health Records and Administrative Data for Public Health Surveillance of Eye Health and Vision-Related Conditions

    Science.gov (United States)

    Elliott, Amanda; Davidson, Arthur; Lum, Flora; Chiang, Michael; Saaddine, Jinan B; Zhang, Xinzhi; Crews, John E.; Chou, Chiu-Fang

    2014-01-01

    Purpose To discuss the current trend toward greater use of electronic health records and how these records could enhance public health surveillance of eye health and vision-related conditions. Methods We describe three currently available sources of electronic health data (Kaiser Permanente, the Veterans Health Administration, and the Centers for Medicare & Medicaid Services) and how these sources can contribute to a comprehensive vision and eye health surveillance system. Results Each of the three sources of electronic health data can contribute meaningfully to a comprehensive vision and eye health surveillance system, but none currently provide all the information required. The use of electronic health records for vision and eye health surveillance has both advantages and disadvantages. Conclusions Electronic health records may provide additional information needed to create a comprehensive vision and eye health surveillance system. Recommendations for incorporating electronic health records into such a system are presented. PMID:23158225

  7. Medium-Bandgap Small-Molecule Donors Compatible with Both Fullerene and Nonfullerene Acceptors.

    Science.gov (United States)

    Huo, Yong; Yan, Cenqi; Kan, Bin; Liu, Xiao-Fei; Chen, Li-Chuan; Hu, Chen-Xia; Lau, Tsz-Ki; Lu, Xinhui; Sun, Chun-Lin; Shao, Xiangfeng; Chen, Yongsheng; Zhan, Xiaowei; Zhang, Hao-Li

    2018-03-21

    Much effort has been devoted to the development of new donor materials for small-molecule organic solar cells due to their inherent advantages of well-defined molecular weight, easy purification, and good reproducibility in photovoltaic performance. Herein, we report two small-molecule donors that are compatible with both fullerene and nonfullerene acceptors. Both molecules consist of an (E)-1,2-di(thiophen-2-yl)ethane-substituted (TVT-substituted) benzo[1,2-b:4,5-b']dithiophene (BDT) as the central unit, and two rhodanine units as the terminal electron-withdrawing groups. The central units are modified with either alkyl side chains (DRBDT-TVT) or alkylthio side chains (DRBDT-STVT). Both molecules exhibit a medium bandgap with complementary absorption and proper energy level offset with typical acceptors like PC 71 BM and IDIC. The optimized devices show a decent power conversion efficiency (PCE) of 6.87% for small-molecule organic solar cells and 6.63% for nonfullerene all small-molecule organic solar cells. Our results reveal that rationally designed medium-bandgap small-molecule donors can be applied in high-performance small-molecule organic solar cells with different types of acceptors.

  8. Near infrared organic light-emitting diodes based on acceptor-donor-acceptor (ADA) using novel conjugated isatin Schiff bases

    International Nuclear Information System (INIS)

    Taghi Sharbati, Mohammad; Soltani Rad, Mohammad Navid; Behrouz, Somayeh; Gharavi, Alireza; Emami, Farzin

    2011-01-01

    Fabrications of a single layer organic light emitting diodes (OLEDs) based on two conjugated acceptor-donor-acceptor (ADA) isatin Schiff bases are described. The electroluminescent spectra of these materials range from 630 to 700 nm and their band gaps were measured between 1.97 and 1.77 eV. The measured maximum external quantum efficiencies (EQE) for fabricated OLEDs are 0.0515% and 0.054% for two acceptor-donor-acceptor chromophores. The Commission International De L'Eclairage (CIE) (1931) coordinates of these two compounds were attained and found to be (0.4077, 0.4128) and (0.4411, 0.4126) for two used acceptor-donor-acceptor chromophores. The measured I-V curves demonstrated the apparent diode behavior of two ADA chromophores. The turn-on voltages in these OLEDs are directly dependent on the thickness. These results have demonstrated that ADA isatin Schiff bases could be considered as promising electroluminescence-emitting materials for fabrication of OLEDs.

  9. Bane of Hydrogen-Bond Formation on the Photoinduced Charge-Transfer Process in Donor–Acceptor Systems

    KAUST Repository

    Alsam, Amani Abdu

    2017-03-14

    Controlling the ultrafast dynamical process of photoinduced charge transfer at donor acceptor interfaces remains a major challenge for physical chemistry and solar cell communities. The process is complicated by the involvement of other complex dynamical processes, including hydrogen bond formation, energy transfer, and solvation dynamics occurring on similar time scales. In this study, we explore the remarkable impact of hydrogen-bond formation on the interfacial charge transfer between a negatively charged electron donating anionic porphyrin and a positively charged electron accepting pi-conjugated polymer, as a model system in solvents with different polarities and capabilities for hydiogen bonding using femtosecond transient absorption spectroscopy. Unlike the conventional understanding of the key role of hydrogen bonding in promoting the charge-transfer process, our steadystate and time-resolved results reveal that the intervening hydrogen-bonding environment and, consequently, the probable longer spacing between the donor and acceptor molecules significantly hinders the charge-transfer process between them. These results show that site-specific hydrogen bonding and geometric considerations between donor and acceptor can be exploited to control both the charge-transfer dynamics and its efficiency not only at donor acceptor interfaces but also in complex biological systems.

  10. Basic Conditions of Validity of Electronic Contracts in Iran and UNCITRAL Model Law

    Directory of Open Access Journals (Sweden)

    Abbas Karimi

    2017-02-01

    Full Text Available Diverse activities such as electronic exchange of goods and services, instant digital content delivery, electronic funds transfer, electronic stock exchange, electronic bill of lading, commercial projects, common engineering and design, sourcing, government purchase, direct marketing and post-sales services included in e-commerce field.  Due to the increasing spread of the electronic world in all aspects, electronic contracts, in turn, was of great importance and made significant contributions in business contracts. The present study aims to investigate the concept, fundamentals and history of electronic contracts referring to UNCITRAL Model Law on Electronic Commerce and Electronic Commerce Act (1996. The results indicate that in terms of the conclusion and obligations of the parties, contract in cyberspace in general is similar to the contract in the real world and in this respect, there is no major difference between these two contexts. Potential electronic contracts considered as written ones and Electronic signatures recognized as valid as the basis of the validity of the will in electronic trading.

  11. Processes of electron attachment and detachment in near breakdown conditions in air plasma

    Science.gov (United States)

    Ardelyan, N.; Bychkov, V.; Belousov, A.; Kosmachevskii, K.

    2017-11-01

    Results of theoretical research on ionization of dry air at different low and moderate values of constant electric field are described. Special attention to the processes of electron attachment to oxygen molecules and electron detachment from negative ions has been paid. New data on the detachment of electrons from oxygen molecular negative ions are taken into account.

  12. Motives and perceptions regarding electronic nicotine delivery systems (ENDS) use among adults with mental health conditions.

    Science.gov (United States)

    Spears, Claire Adams; Jones, Dina M; Weaver, Scott R; Pechacek, Terry F; Eriksen, Michael P

    2018-05-01

    Smoking rates are disproportionately high among adults with mental health conditions (MHC), and recent research suggests that among former smokers, those with MHC are more likely to use electronic nicotine delivery systems (ENDS). This study investigated reasons for ENDS use and related risk perceptions among individuals with versus without MHC. Among adult current ENDS users (n=550), associations between self-reported MHC diagnoses and motives for ENDS use and ENDS risk perceptions were examined, stratified by smoking status. There were no significant associations between MHC status and ENDS motives or perceptions in the overall sample. However, current smokers with MHC indicated thinking more about how ENDS might improve their health, and former smokers with MHC reported thinking less about how ENDS might harm their health, compared to their counterparts without MHC. Former smokers with MHC rated several reasons for ENDS use (e.g., less harmful than regular cigarettes; to quit smoking; appealing flavors) as more important than did those without MHC. Current and former smokers with MHC may be especially optimistic about health benefits of ENDS. However, they might also be prone to health risks of continued ENDS use or concurrent use with traditional cigarettes. It will be important for public health messaging to provide this population with accurate information about benefits and risks of ENDS. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. The CMS Fast Beams Condition Monitor Backend Electronics based on MicroTCA technology

    CERN Document Server

    Zagozdzinska, Agnieszka Anna

    2016-01-01

    The Fast Beams Condition Monitor (BCM1F), upgraded for LHC Run II, is one sub-system of the Beam Radiation Instrumentation and Luminosity Project of the CMS experiment. It is based on 24 single crystal CVD diamond sensors. Each sensor is metallised with two pads, being read out by a dedicated fast frontend chip produced in 130 nm CMOS technology. Signals for real time monitoring are processed by custom-made back-end electronics to measure separately rates corresponding to LHC collision products, machine induced background and residual activation exploiting different arrival times. The system is built in MicroTCA technology and uses high speed analog-to-digital converters. The data processing module designed for the FPGA allows a distinguishing of collision and machine induced background, both synchronous to the LHC clock, from the residual activation products. In operational modes of high rates, consecutive events, spaced in time by less than 12.5 ns, may partially overlap. Hence, novel signal processing tec...

  14. Use of Electronic Nicotine Delivery Systems among Adults with Mental Health Conditions, 2015

    Directory of Open Access Journals (Sweden)

    Claire Adams Spears

    2016-12-01

    Full Text Available Adults with mental health conditions (MHC are especially likely to smoke and experience tobacco-related health disparities. Individuals with MHC may also use electronic nicotine delivery devices (ENDS at disproportionately high rates. However, there is a relative dearth of knowledge regarding ENDS use among individuals with MHC. In a large representative sample of U.S. adults (n = 6051, associations between self-reported MHC diagnoses and ENDS use and susceptibility were examined, stratified by smoking status. Participants with MHC were approximately 1.5 times more likely to have used ENDS in their lifetime and almost twice as likely to currently use ENDS as those without MHC. MHC status was most strongly linked to higher ENDS use among former smokers, and former smokers with MHC were more likely to report using ENDS during past smoking quit attempts than those without MHC. Among participants who had not tried ENDS, former smokers with MHC were especially susceptible to future ENDS use. The potential advantage of ENDS for cessation purposes should be balanced with the risk of attracting former smokers with MHC to ENDS.

  15. Performance of the Fuel Conditioning Facility electronic in-cell mass balances

    International Nuclear Information System (INIS)

    Orechwa, Y.; Bucher, R.G.

    1996-01-01

    An approach to error estimation and measurement control in the analysis of the balance measurements of mass standards on the in-cell electronic mass balances of the Fuel Conditioning Facility is presented. In light of measurement data from one year of operation, the algorithms proposed are evaluated. The need to take into account the effects of facility operations on the estimates of measurement uncertainty is demonstrated. In the case of a newly installed balance, where no historical data exists, an ad hoc procedure of adding a term which takes into account the operational variability is proposed. This procedure allows a sufficiently long operation so as to collect data for the estimate of the contribution of operational effects to the uncertainty estimate. An algorithm for systematically taking into account historical data is developed and demonstrated for two balances over two calibration periods. The algorithm, both asymptotically and in the two samples cases, has the necessary desirable properties for estimating the uncertainty in the measurements of the balances

  16. Fast electron accumulation and its mechanism in a harmonic trap under ultrahigh vacuum conditions

    International Nuclear Information System (INIS)

    Mohamed, T.; Imao, H.; Mohri, A.; Oshima, N.; Yamazaki, Y.

    2011-01-01

    We present here a fast and efficient electron accumulation in a multiring trap (MRT) in a superconducting solenoid of 5 T. More than 10 10 electrons were accumulated within a fraction of a second for an electron beam in the range of 10 -7 A. The MRT was installed in a cryogenic bore tube cooled down to ∼10 K. Electron accumulation as a function of various parameters such as the beam intensity, the MRT depth, and the MRT length was studied. We succeeded in extracting a consistent picture of the electron accumulation mechanisms, which consist of interactions of the incoming electron beam with the reflected beam and with the electrons trapped in the MRT.

  17. Donor-Acceptor Interface Stabilizer Based on Fullerene Derivatives toward Efficient and Thermal Stable Organic Photovoltaics.

    Science.gov (United States)

    Li, Junli; Zhu, Xiaoguang; Yuan, Tao; Shen, Jiulin; Liu, Jikang; Zhang, Jian; Tu, Guoli

    2017-02-22

    An interface stabilizer based on alkylation-functionalized fullerene derivatives, [6, 6]-Phenyl-C61-butyric acid (3,5-bis(octyloxy)phenyl)methyl ester (PCB-C8oc), was successfully synthesized and applied for the active layer of Organic Photovoltaics (OPVs). The PCB-C8oc can replace part of the phenyl-C61-buty-ric acid methyl ester (PCBM) and be distributed on the interface of poly(3-hexylthiophene) (P3HT) and PCBM to form P3HT/PCBM/PCB-C8oc ternary blends, leading to thermally stable and efficient organic photovoltaics. The octyl groups of PCB-C8oc exhibit intermolecular interaction with the hexyl groups of P3HT, and the fullerene unit of PCB-C8oc are in tight contact with PCBM. The dual functions of PCB-C8oc will inhibit the phase separation between electron donor and acceptor, thereby improving the stability of devices under long-time thermal annealing at high temperature. When doped with 10 wt % PCB-C8oc, the power conversion efficiency (PCE) of the P3HT system decreased from 3.54% to 2.88% after 48 h of thermal treatment at 150 °C, whereas the PCE of the reference device without PCB-C8oc dramatically dropped from 3.53% to 0.73%. When doping 10 or 20 wt % PCB-C8oc, the unannealed P3HT/PCBM/PCB-C8oc device achieved a higher PCE than the P3HT/PCBM device without any annealing following the same fabricating condition. For the PTB7/PCBM-based devices, after adding only 5 wt % PCB-C8oc, the OPVs also exhibited thermally stable morphology and better device performances. All these results demonstrate that the utilization of alkyl interchain interactions is an effective and practical strategy to control morphological evolution.

  18. On the coexistence of localized and extended acceptor states in high gap semiconductors

    International Nuclear Information System (INIS)

    Schirmer, O F

    2015-01-01

    Holes introduced into high gap materials by acceptor doping are often self-localized at anion sites as small polarons bound to the doping elements. The related lattice distortion lowers the hole energy; the hole levels thus tend to be deep. Electronic structure calculations of small polarons have identified, for some dopings, that such localized states can coexist with extended ones that result from the same doping. Using a scaling formalism, proposed by Emin and Holstein, it is shown that this appears to be a general phenomenon if the polaron-forming short-range hole–lattice coupling is taken into account. (invited article)

  19. A Selenophene-Based Low-Bandgap Donor-Acceptor Polymer Leading to Fast Ambipolar Logic

    KAUST Repository

    Kronemeijer, Auke J.

    2012-02-20

    Fast ambipolar CMOS-like logic is demonstrated using a new selenophene-based donor-acceptor polymer semiconductor. The polymer exhibits saturation hole and electron mobilities of 0.46 cm 2/Vs and 0.84 cm 2/Vs. Inverters are fabricated with high gains while three-stage ring oscillators show stable oscillation with an unprecedented maximum frequency of 182 kHz at a relatively low supply voltage of 50 V. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Transferase Activity of Lactobacillal and Bifidobacterial β-Galactosidases with Various Sugars as Galactosyl Acceptors.

    Science.gov (United States)

    Arreola, Sheryl Lozel; Intanon, Montira; Wongputtisin, Pairote; Kosma, Paul; Haltrich, Dietmar; Nguyen, Thu-Ha

    2016-03-30

    The β-galactosidases from Lactobacillus reuteri L103 (Lreuβgal), Lactobacillus delbrueckii subsp. bulgaricus DSM 20081 (Lbulβgal), and Bifidobacterium breve DSM 20281 (Bbreβgal-I and Bbreβgal-II) were investigated in detail with respect to their propensity to transfer galactosyl moieties onto lactose, its hydrolysis products D-glucose and D-galactose, and certain sugar acceptors such as N-acetyl-D-glucosamine (GlcNAc), N-acetyl-D-galactosamine (GalNAc), and L-fucose (Fuc) under defined, initial velocity conditions. The rate constants or partitioning ratios (kNu/kwater) determined for these different acceptors (termed nucleophiles, Nu) were used as a measure for the ability of a certain substance to act as a galactosyl acceptor of these β-galactosidases. When using Lbulβgal or Bbreβgal-II, the galactosyl transfer to GlcNAc was 6 and 10 times higher than that to lactose, respectively. With lactose and GlcNAc used in equimolar substrate concentrations, Lbulβgal and Bbreβgal-II catalyzed the formation of N-acetyl-allolactosamine with the highest yields of 41 and 24%, respectively, as calculated from the initial GlcNAc concentration.

  1. An overview of molecular acceptors for organic solar cells

    Science.gov (United States)

    Hudhomme, Piétrick

    2013-07-01

    Organic solar cells (OSCs) have gained serious attention during the last decade and are now considered as one of the future photovoltaic technologies for low-cost power production. The first dream of attaining 10% of power coefficient efficiency has now become a reality thanks to the development of new materials and an impressive work achieved to understand, control and optimize structure and morphology of the device. But most of the effort devoted to the development of new materials concerned the optimization of the donor material, with less attention for acceptors which to date remain dominated by fullerenes and their derivatives. This short review presents the progress in the use of non-fullerene small molecules and fullerene-based acceptors with the aim of evaluating the challenge for the next generation of acceptors in organic photovoltaics.

  2. An overview of molecular acceptors for organic solar cells

    Directory of Open Access Journals (Sweden)

    Hudhomme Piétrick

    2013-07-01

    Full Text Available Organic solar cells (OSCs have gained serious attention during the last decade and are now considered as one of the future photovoltaic technologies for low-cost power production. The first dream of attaining 10% of power coefficient efficiency has now become a reality thanks to the development of new materials and an impressive work achieved to understand, control and optimize structure and morphology of the device. But most of the effort devoted to the development of new materials concerned the optimization of the donor material, with less attention for acceptors which to date remain dominated by fullerenes and their derivatives. This short review presents the progress in the use of non-fullerene small molecules and fullerene-based acceptors with the aim of evaluating the challenge for the next generation of acceptors in organic photovoltaics.

  3. Empirical models of Total Electron Content based on functional fitting over Taiwan during geomagnetic quiet condition

    Directory of Open Access Journals (Sweden)

    Y. Kakinami

    2009-08-01

    Full Text Available Empirical models of Total Electron Content (TEC based on functional fitting over Taiwan (120° E, 24° N have been constructed using data of the Global Positioning System (GPS from 1998 to 2007 during geomagnetically quiet condition (Dst>−30 nT. The models provide TEC as functions of local time (LT, day of year (DOY and the solar activity (F, which are represented by 1–162 days mean of F10.7 and EUV. Other models based on median values have been also constructed and compared with the models based on the functional fitting. Under same values of F parameter, the models based on the functional fitting show better accuracy than those based on the median values in all cases. The functional fitting model using daily EUV is the most accurate with 9.2 TECu of root mean square error (RMS than the 15-days running median with 10.4 TECu RMS and the model of International Reference Ionosphere 2007 (IRI2007 with 14.7 TECu RMS. IRI2007 overestimates TEC when the solar activity is low, and underestimates TEC when the solar activity is high. Though average of 81 days centered running mean of F10.7 and daily F10.7 is often used as indicator of EUV, our result suggests that average of F10.7 mean from 1 to 54 day prior and current day is better than the average of 81 days centered running mean for reproduction of TEC. This paper is for the first time comparing the median based model with the functional fitting model. Results indicate the functional fitting model yielding a better performance than the median based one. Meanwhile we find that the EUV radiation is essential to derive an optimal TEC.

  4. Interaction of 125I-labeled botulinum neurotoxins with nerve terminals. II. Autoradiographic evidence for its uptake into motor nerves by acceptor-mediated endocytosis

    International Nuclear Information System (INIS)

    Black, J.D.; Dolly, J.O.

    1986-01-01

    Using pharmacological and autoradiographic techniques it has been shown that botulinum neurotoxin (BoNT) is translocated across the motor nerve terminal membrane to reach a postulated intraterminal target. In the present study, the nature of this uptake process was investigated using electron microscopic autoradiography. It was found that internalization is acceptor-mediated and that binding to specific cell surface acceptors involves the heavier chain of the toxin. In addition, uptake was shown to be energy and temperature-dependent and to be accelerated by nerve stimulation, a treatment which also shortens the time course of the toxin-induced neuroparalysis. These results, together with the observation that silver grains were often associated with endocytic structures within the nerve terminal, suggested that acceptor-mediated endocytosis is responsible for toxin uptake. Possible recycling of BoNT acceptors (an important aspect of acceptor-mediated endocytosis of toxins) at motor nerve terminals was indicated by comparing the extent of labeling in the presence and absence of metabolic inhibitors. On the basis of these collective results, it is concluded that BoNT is internalized by acceptor-mediated endocytosis and, hence, the data support the proposal that this toxin inhibits release of acetylcholine by interaction with an intracellular target

  5. 75 FR 77569 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Flight Control System Mode...

    Science.gov (United States)

    2010-12-13

    ... Control System Mode Annunciation AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... electronic flight control system. The applicable airworthiness regulations do not contain adequate or... Unusual Design Features The GVI will have a fly-by-wire electronic flight control system. This system...

  6. Graphene oxide-Li(+)@C60 donor-acceptor composites for photoenergy conversion.

    Science.gov (United States)

    Supur, Mustafa; Kawashima, Yuki; Ohkubo, Kei; Sakai, Hayato; Hasobe, Taku; Fukuzumi, Shunichi

    2015-06-28

    An ionic endohedral metallofullerene (Li(+)@C60) with mild hydrophilic nature was combined with graphene oxide (GO) to construct a donor-acceptor composite in neat water. The resulting composite was characterised by UV-Vis and Raman spectroscopy, powder X-ray diffraction, dynamic light scattering measurements and transmission electron microscopy. Theoretical calculations (DFT at the B3LYP/6-31(d) level) were also utilized to gain further insight into the composite formation. As detected by electron paramagnetic resonance spectroscopy, photoexcitation of the GO-Li(+)@C60 composite results in electron transfer from GO to the triplet excited state of Li(+)@C60, leading to photocurrent generation at the OTE/SnO2 electrode.

  7. Fluorinated arene, imide and unsaturated pyrrolidinone based donor acceptor conjugated polymers: Synthesis, structure-property and device studies

    Science.gov (United States)

    Liyanage, Arawwawala Don Thilanga

    After the discovery of doped polyacetylene, organic semiconductor materials are widely studied as high impending active components in consumer electronics. They have received substantial consideration due to their potential for structural tailoring, low cost, large area and mechanically flexible alternatives to common inorganic semiconductors. To acquire maximum use of these materials, it is essential to get a strong idea about their chemical and physical nature. Material chemist has an enormous role to play in this novel area, including development of efficient synthetic methodologies and control the molecular self-assembly and (opto)-electronic properties. The body of this thesis mainly focuses on the substituent effects: how different substituents affect the (opto)-electronic properties of the donor-acceptor (D-A) conjugated polymers. The main priority goes to understand, how different alkyl substituent effect to the polymer solubility, crystallinity, thermal properties (e.g.: glass transition temperature) and morphological order. Three classes of D-A systems were extensively studied in this work. The second chapter mainly focuses on the synthesis and structure-property study of fluorinated arene (TFB) base polymers. Here we used commercially available 1,4-dibromo-2,3,5,6-tetrafluorobenzene (TFB) as the acceptor material and prepare several polymers using 3,3'-dialkyl(3,3'-R2T2) or 3,3'-dialkoxy bithiophene (3,3'-RO2T2) units as electron donors. A detail study was done using 3,3'-bithiophene donor units incorporating branched alkoxy-functionalities by systematic variation of branching position and chain length. The study allowed disentangling the branching effects on (i) aggregation tendency, intermolecular arrangement, (iii) solid state optical energy gaps, and (iv) electronic properties in an overall consistent picture, which might guide future polymer synthesis towards optimized materials for opto-electronic applications. The third chapter mainly focused on

  8. Spectrophotometric study of the charge-transfer and ion-pair complexation of methamphetamine with some acceptors

    Science.gov (United States)

    Shahdousti, Parvin; Aghamohammadi, Mohammad; Alizadeh, Naader

    2008-04-01

    The charge-transfer (CT) complexes of methamphetamine (MPA) as a n-donor with several acceptors including bromocresolgreen (BCG), bromocresolpurple (BCP), chlorophenolred (CPR), picric acid (PIC), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) have been studied spectrophotometrically in chloroform solutions in order to obtain some information about their stoichiometry and stability of complexation. The oscillator strengths, transition dipole moments and resonance energy of the complex in the ground state for all complexes have been calculated. Vertical ionization potential of MPA and electron affinity of acceptors were determined by ab initio calculation. The acceptors were also used to utilize a simple and sensitive extraction-spectrophotometric method for the determination of MPA. The method is based on the formation of 1:1 ion-pair association complexes of MPA with BCG, BCP and PIC in chloroform medium. Beer's plots were obeyed in a general concentration range of 0.24-22 μg ml -1 for the investigated drug with different acceptors. The proposed methods were applied successfully for the determination of MAP in pure and abuse drug with good accuracy and precision.

  9. Humidity Build-Up in a Typical Electronic Enclosure Exposed to Cycling Conditions and Effect on Corrosion Reliability

    DEFF Research Database (Denmark)

    Conseil, Helene; Gudla, Visweswara Chakravarthy; Jellesen, Morten Stendahl

    2016-01-01

    The design of electronic device enclosures plays a major role in determining the humidity build-up inside the device as a response to the varying external humidity. Therefore, the corrosion reliability of electronic devices has direct connection to the enclosure design. This paper describes...... the internal humidity build-up in a typical enclosure prescribed for electronic applications as a function of external humidity conditions and enclosure-related parameters. Investigated parameters include external temperature and humidity conditions, the temperature and time of the internal heating cycle......, thermal mass, and port/opening size. The effect of the internal humidity build-up on corrosion reliability has been evaluated by measuring the leakage current (LC) on interdigitated test comb patterns, which are precontaminated with sodium chloride and placed inside the enclosure. The results showed...

  10. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO2

    International Nuclear Information System (INIS)

    Mandal, Suman; Pal, Somnath; Hazarika, Abhijit; Kundu, Asish K.; Menon, Krishnakumar S. R.; Rioult, Maxime; Belkhou, Rachid

    2016-01-01

    Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO 2 have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.

  11. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Suman, E-mail: suman.mandal@sscu.iisc.ernet.in; Pal, Somnath; Hazarika, Abhijit [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012 (India); Kundu, Asish K.; Menon, Krishnakumar S. R. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Rioult, Maxime; Belkhou, Rachid [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, 91192 Gif-sur-Yvette (France)

    2016-08-29

    Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO{sub 2} have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.

  12. Comparison among four commonly used demineralizing agents for root conditioning: a scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Nathalia Godoy do Amaral

    2011-10-01

    Full Text Available Dental roots that have been exposed to the oral cavity and periodontal pocket environment present superficial changes, which can prevent connective tissue reattachment. Demineralizing agents have been used as an adjunct to the periodontal treatment aiming at restoring the biocompatibility of roots. OBJECTIVE: This study compared four commonly used demineralizing agents for their capacity of removing smear layer and opening dentin tubules. METHODS: Fifty fragments of human dental roots previously exposed to periodontal disease were scaled and randomly divided into the following groups of treatment: 1 CA: demineralization with citric acid for 3 min; 2 TC-HCl: demineralization with tetracycline-HCl for 3 min; 3 EDTA: demineralization with EDTA for 3 min; 4 PA: demineralization with 37% phosphoric acid for 3 min; 5 Control: rubbing of saline solution for 3 min. Scanning electron microscopy was used to check for the presence of residual smear layer and for measuring the number and area of exposed dentin tubules. RESULTS: Smear layer was present in 100% of the specimens from the groups PA and control; in 80% from EDTA group; in 33.3% from TC-HCl group and 0% from CA group. The mean numbers of exposed dentin tubules in a standardized area were: TC-HCl=43.8±25.2; CA=39.3±37; PA=12.1±16.3; EDTA=4.4±7.5 and Control=2.3±5.7. The comparison showed significant differences between the following pairs of groups: TC-HCl and Control; TC-HCl and EDTA; CA and Control; and CA and EDTA. The mean percentages of area occupied by exposed dentin tubules were: CA=0.12±0.17%; TC-HCl=0.08±0.06%; PA=0.03±0.05%; EDTA=0.01±0.01% and Control=0±0%. The CA group differed significantly from the others except for the TC-HCl group. CONCLUSION: There was a decreasing ability for smear layer removal and dentin tubule widening as follows: AC>TC-HCl>PA>EDTA. This information can be of value as an extra parameter for choosing one of them for root conditioning.

  13. 78 FR 73993 - Special Conditions: Cessna Model 680 Series Airplanes; Aircraft Electronic System Security...

    Science.gov (United States)

    2013-12-10

    ... systems and networks. Connectivity to, or access by, external systems and networks may result in security... and network configuration may allow the exploitation of network security vulnerabilities resulting in... Electronic System Security Protection From Unauthorized External Access AGENCY: Federal Aviation...

  14. 78 FR 75451 - Special Conditions: Cessna Model 750 Series Airplanes; Aircraft Electronic System Security...

    Science.gov (United States)

    2013-12-12

    ... systems and networks. Connectivity to, or access by, external systems and networks may result in security... and network configuration may allow the exploitation of network security vulnerabilities resulting in... Electronic System Security Protection From Unauthorized External Access AGENCY: Federal Aviation...

  15. Partial least squares prediction of the first hyperpolarizabilities of donor-acceptor polyenic derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Machado, A.E. de A, E-mail: aeam@rpd.ufmg.br [Laboratorio de Quimica Computacional e Modelagem Molecular (LQC-MM), Departamento de Quimica, ICEx, Universidade Federal de Minas Gerais (UFMG), Campus Universitario, Pampulha, Belo Horizonte, MG 31270-90 (Brazil); Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Recife, PE 50740-540 (Brazil); Gama, A.A. de S da; Barros Neto, B. de [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Recife, PE 50740-540 (Brazil)

    2011-09-22

    Graphical abstract: PLS regression equations predicts quite well static {beta} values for a large set of donor-acceptor organic molecules, in close agreement with the available experimental data. Display Omitted Highlights: {yields} PLS regression predicts static {beta} values of 35 push-pull organic molecules. {yields} PLS equations show correlation of {beta} with structural-electronic parameters. {yields} PLS regression selects best components of push-bridge-pull nonlinear compounds. {yields} PLS analyses can be routinely used to select novel second-order materials. - Abstract: A partial least squares regression analysis of a large set of donor-acceptor organic molecules was performed to predict the magnitude of their static first hyperpolarizabilities ({beta}'s). Polyenes, phenylpolyenes and biphenylpolyenes with augmented chain lengths displayed large {beta} values, in agreement with the available experimental data. The regressors used were the HOMO-LUMO energy gap, the ground-state dipole moment, the HOMO energy AM1 values and the number of {pi}-electrons. The regression equation predicts quite well the static {beta} values for the molecules investigated and can be used to model new organic-based materials with enhanced nonlinear responses.

  16. Partial least squares prediction of the first hyperpolarizabilities of donor-acceptor polyenic derivatives

    International Nuclear Information System (INIS)

    Machado, A.E. de A; Gama, A.A. de S da; Barros Neto, B. de

    2011-01-01

    Graphical abstract: PLS regression equations predicts quite well static β values for a large set of donor-acceptor organic molecules, in close agreement with the available experimental data. Display Omitted Highlights: → PLS regression predicts static β values of 35 push-pull organic molecules. → PLS equations show correlation of β with structural-electronic parameters. → PLS regression selects best components of push-bridge-pull nonlinear compounds. → PLS analyses can be routinely used to select novel second-order materials. - Abstract: A partial least squares regression analysis of a large set of donor-acceptor organic molecules was performed to predict the magnitude of their static first hyperpolarizabilities (β's). Polyenes, phenylpolyenes and biphenylpolyenes with augmented chain lengths displayed large β values, in agreement with the available experimental data. The regressors used were the HOMO-LUMO energy gap, the ground-state dipole moment, the HOMO energy AM1 values and the number of π-electrons. The regression equation predicts quite well the static β values for the molecules investigated and can be used to model new organic-based materials with enhanced nonlinear responses.

  17. Investigation of Donor and Acceptor Ion Implantation in AlN

    Energy Technology Data Exchange (ETDEWEB)

    Osinsky, Andrei [Agnitron Technology Inc., Eden Prairie, MN (United States)

    2015-09-16

    AlGaN alloys with high Al composition and AlN based electronic devices are attractive for high voltage, high temperature applications, including microwave power sources, power switches and communication systems. AlN is of particular interest because of its wide bandgap of ~6.1eV which is ideal for power electronic device applications in extreme environments which requires high dose ion implantation. One of the major challenges that need to be addressed to achieve full utilization of AlN for opto and microelectronic applications is the development of a doping strategy for both donors and acceptors. Ion implantation is a particularly attractive approach since it allows for selected-area doping of semiconductors due to its high spatial and dose control and its high throughput capability. Active layers in the semiconductor are created by implanting a dopant species followed by very high temperature annealing to reduce defects and thereby activate the dopants. Recovery of implant damage in AlN requires excessively high temperature. In this SBIR program we began the investigation by simulation of ion beam implantation profiles for Mg, Ge and Si in AlN over wide dose and energy ranges. Si and Ge are implanted to achieve the n-type doping, Mg is investigated as a p-type doping. The simulation of implantation profiles were performed in collaboration between NRL and Agnitron using a commercial software known as Stopping and Range of Ions in Matter (SRIM). The simulation results were then used as the basis for ion implantation of AlN samples. The implanted samples were annealed by an innovative technique under different conditions and evaluated along the way. Raman spectroscopy and XRD were used to determine the crystal quality of the implanted samples, demonstrating the effectiveness of annealing in removing implant induced damage. Additionally, SIMS was used to verify that a nearly uniform doping profile was achieved near the sample surface. The electrical characteristics

  18. Lipase-catalyzed biodiesel production with methyl acetate as acyl acceptor

    Energy Technology Data Exchange (ETDEWEB)

    Huang Ying; Yan Yunjun [School of Life Science and Technology, Huazhong Univ. of Science and Technology, Wuhan (China)

    2008-03-15

    Biodiesel is an alternative diesel fuel made from renewable biological resources. During the process of biodiesel production, lipase-catalyzed transesterification is a crucial step. However, current techniques using methanol as acyl acceptor have lower enzymatic activity; this limits the application of such techniques in large-scale biodiesel production. Furthermore, the lipid feedstock of currently available techniques is limited. In this paper, the technique of lipase-catalyzed transesterification of five different oils for biodiesel production with methyl acetate as acyl acceptor was investigated, and the transesterification reaction conditions were optimized. The operation stability of lipase under the obtained optimal conditions was further examined. The results showed that under optimal transesterification conditions, both plant oils and animal fats led to high yields of methyl ester: cotton-seed oil, 98%; rape-seed oil, 95%; soybean oil, 91%; tea-seed oil, 92%; and lard, 95%. Crude and refined cotton-seed oil or lard made no significant difference in yields of methyl ester. No loss of enzymatic activity was detected for lipase after being repeatedly used for 40 cycles (ca. 800 h), which indicates that the operational stability of lipase was fairly good under these conditions. Our results suggest that cotton-seed oil, rape-seed oil and lard might substitute soybean oil as suitable lipid feedstock for biodiesel production. Our results also show that our technique is fit for various lipid feedstocks both from plants and animals, and presents a very promising way for the large-scale biodiesel production. (orig.)

  19. Equivalence of donor and acceptor fits of temperature dependent Hall carrier density and Hall mobility data: Case of ZnO

    International Nuclear Information System (INIS)

    Brochen, Stéphane; Feuillet, Guy; Pernot, Julien

    2014-01-01

    In this work, statistical formulations of the temperature dependence of ionized and neutral impurity concentrations in a semiconductor, needed in the charge balance equation and for carrier scattering calculations, have been developed. These formulations have been used in order to elucidate a confusing situation, appearing when compensating acceptor (donor) levels are located sufficiently close to the conduction (valence) band to be thermally ionized and thereby to emit (capture) an electron to (from) the conduction (valence) band. In this work, the temperature dependent Hall carrier density and Hall mobility data adjustments are performed in an attempt to distinguish the presence of a deep acceptor or a deep donor level, coexisting with a shallower donor level and located near the conduction band. Unfortunately, the present statistical developments, applied to an n-type hydrothermal ZnO sample, lead in both cases to consistent descriptions of experimental Hall carrier density and mobility data and thus do not allow to determine the nature, donor or acceptor, of the deep level. This demonstration shows that the emission of an electron in the conduction band, generally assigned to a (0/+1) donor transition from a donor level cannot be applied systematically and could also be attributed to a (−1/0) donor transition from an acceptor level. More generally, this result can be extended for any semiconductor and also for deep donor levels located close to the valence band (acceptor transition)

  20. Clinical Performance of Magnetic Resonance Imaging Conditional and Nonconditional Cardiac Implantable Electronic Devices.

    Science.gov (United States)

    Shah, Anand D; Patel, Adarsh U; Knezevic, Andrea; Hoskins, Michael H; Hirsh, David S; Merchant, Faisal M; El Chami, Mikhael F; Delurgio, David B; Patel, Anshul M; Leon, Angel R; Langberg, Jonathan J; Lloyd, Michael S

    2017-05-01

    This study compared risks associated with magnetic resonance imaging (MRI) in patients with non-MRI conditional and MRI conditional pacing and defibrillator systems with particular attention to clinically actionable outcomes. While recipients of new MRI conditional pacemaker and defibrillator systems may undergo MRI scanning with very low risk, safety and regulatory concerns persist regarding such scanning in recipients of non-MRI conditional systems. Patients with any cardiac device who were referred for MRI were prospectively enrolled at a single center and underwent scanning at 1.5 Tesla. Pre- and postscan lead characteristic changes, system integrity, and symptoms were analyzed. A comparison was made between non-MRI conditional and MRI conditional devices. 105 patients were evaluated allowing for comparison of 97 scans with non-MRI conditional devices and 16 scans with MRI conditional devices. The cohort included those with pacemaker dependency, defibrillator, and cardiac resynchronization devices. Small, nonsignificant changes were observed in lead characteristics following scanning, and there was no significant difference when comparing non-MRI and MRI conditional devices. Lead parameter changes did not require lead revision or programming changes. No device reset, failures, or premature scan termination was observed. 1.5 T MRI scanning in patients with MRI conditional and non-MRI conditional cardiac devices was performed with similar, low clinical risk. © 2017 Wiley Periodicals, Inc.

  1. Architecture of the upgraded BCM1F Backend Electronics for Beam Conditions and Luminosity measurement - hardware and firmware

    CERN Document Server

    Zagozdzinska, Agnieszka Anna

    2014-01-01

    The Beam Radiation Instrumentation and Luminosity Project of the CMS experiment, consists of several beam monitoring systems. One system, the upgraded Fast Beams Condition Monitor, is based on 24 single crystal CVD diamonds with a double-pad sensor metallization and a custom designed readout. Signals for real time monitoring are transmitted to the counting room, where they are received and processed by new back-end electronics designed to extract information on LHC collision, beam induced background and activation products. The Slow Control Driver is designed for the front-end electronics configuration and control. The system architecture and the upgrade status will be presented.

  2. Investigation of instability of M23C6 particles in F82H steel under electron and ion irradiation conditions

    Science.gov (United States)

    Kano, Sho; Yang, Huilong; Shen, Jingjie; Zhao, Zishou; McGrady, John; Hamaguchi, Dai; Ando, Mamami; Tanigawa, Hiroyasu; Abe, Hiroaki

    2018-04-01

    In order to clarify the instability of M23C6 in F82H steel under irradiation, both electron irradiation using a high voltage electron microscope (HVEM) and ion irradiation using an ion accelerator were performed. For the electron irradiation, in-situ observation under 2 MV electron irradiation and ex-situ high resolution electron microscopic (HREM) analysis were utilized to evaluate the response of M23C6 against irradiation. The temperature dependence of the irradiation induced instability of the carbide was first confirmed: 293 K TEM specimens were prepared by a focused ion beam technique. The shrinkage of carbide particles was observed especially near the irradiation surface. Besides, the lattice fringes at the periphery of carbide were observed in the irradiated M23C6 by the HREM analysis, which is different from that observed in the electron irradiation. It was clarified that the instability of M23C6 is dependent on the irradiation conditions, indicating that the flow rate of vacancy type defects might be the key factor to cause the dissolution of constituent atoms of carbide particles into matrix under irradiation.

  3. Synthesis and X-ray crystal structure of the first tetrathiafulvalene-based acceptor-donor-acceptor sandwich

    DEFF Research Database (Denmark)

    Simonsen, Klaus B.; Thorup, Niels; Cava, Michael P.

    1998-01-01

    The synthesis and characterization of a bis-macrocyclic A-D-A sandwich produced in a simple one-pot reaction is reported. Only one acceptor unit participates in charge-transfer interactions with the TTF unit in the solid state....

  4. Photosystem II cycle activity and alternative electron transport in the diatom Phaeodactylum tricornutum under dynamic light conditions and nitrogen limitation.

    Science.gov (United States)

    Wagner, Heiko; Jakob, Torsten; Lavaud, Johann; Wilhelm, Christian

    2016-05-01

    Alternative electron sinks are an important regulatory mechanism to dissipate excessively absorbed light energy particularly under fast changing dynamic light conditions. In diatoms, the cyclic electron transport (CET) around Photosystem II (PS II) is an alternative electron transport pathway (AET) that contributes to avoidance of overexcitation under high light illumination. The combination of nitrogen limitation and high-intensity irradiance regularly occurs under natural conditions and is expected to force the imbalance between light absorption and the metabolic use of light energy. The present study demonstrates that under N limitation, the amount of AET and the activity of CETPSII in the diatom Phaeodactylum tricornutum were increased. Thereby, the activity of CETPSII was linearly correlated with the amount of AET rates. It is concluded that CETPSII significantly contributes to AET in P. tricornutum. Surprisingly, CETPSII was found to be activated already at the end of the dark period under N-limited conditions. This coincided with a significantly increased degree of reduction of the plastoquinone (PQ) pool. The analysis of the macromolecular composition of cells of P. tricornutum under N-limited conditions revealed a carbon allocation in favor of carbohydrates during the light period and their degradation during the dark phase. A possible linkage between the activity of CETPSII and degree of reduction of the PQ pool on the one side and the macromolecular changes on the other is discussed.

  5. Vibrational properties of organic donor-acceptor molecular crystals: Anthracene-pyromellitic-dianhydride (PMDA) as a case study

    KAUST Repository

    Fonari, A.

    2015-12-10

    We establish a reliable quantum-mechanical approach to evaluate the vibrational properties of donor-acceptor molecular crystals. The anthracene-PMDA (PMDA = pyromellitic dianhydride) crystal, where anthracene acts as the electron donor and PMDA as the electron acceptor, is taken as a representative system for which experimental non-resonance Raman spectra are also reported. We first investigate the impact that the amount of nonlocal Hartree-Fock exchange (HFE) included in a hybrid density functional has on the geometry, normal vibrational modes, electronic coupling, and electron-vibrational (phonon) couplings. The comparison between experimental and theoreticalRaman spectra indicates that the results based on the αPBE functional with 25%-35% HFE are in better agreement with the experimental results compared to those obtained with the pure PBE functional. Then, taking αPBE with 25% HFE, we assign the vibrational modes and examine their contributions to the relaxation energy related to the nonlocal electron-vibration interactions. The results show that the largest contribution (about 90%) is due to electron interactions with low-frequency vibrational modes. The relaxation energy in anthracene-PMDA is found to be about five times smaller than the electronic coupling.

  6. FLAVODIIRON2 and FLAVODIIRON4 Proteins Mediate an Oxygen-Dependent Alternative Electron Flow in Synechocystis sp. PCC 6803 under CO2-Limited Conditions1[OPEN

    Science.gov (United States)

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-01-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. PMID:25540330

  7. Spin matching conditions in large electron storage rings with purely horizontal beam polarization

    International Nuclear Information System (INIS)

    Rossmanith, R.

    1990-08-01

    In a storage ring with a purely horizontal spin and a Siberian Snake, the spin matching conditions are similar to the spin matching conditions for vertical polarization; a combination of beam bumps has to be found which compensate the depolarizing effects. These bumps compensate the random emission of synchrotron emission on the spin. The aim of this paper is to define spin matching conditions that compensate this effect

  8. Spin matching conditions in large electron storage rings with purely horizontal beam polarization

    Energy Technology Data Exchange (ETDEWEB)

    Rossmanith, R.

    1990-08-01

    In a storage ring with a purely horizontal spin and a Siberian Snake, the spin matching conditions are similar to the spin matching conditions for vertical polarization; a combination of beam bumps has to be found which compensate the depolarizing effects. These bumps compensate the random emission of synchrotron emission on the spin. The aim of this paper is to define spin matching conditions that compensate this effect.

  9. Possibility to Use Hydrothermally Synthesized CuFeS2 Nanocomposite as an Acceptor in Hybrid Solar Cell

    Science.gov (United States)

    Sil, Sayantan; Dey, Arka; Halder, Soumi; Datta, Joydeep; Ray, Partha Pratim

    2018-01-01

    Here we have approached the plausible use of CuFeS2 nanocomposite as an acceptor in organic-inorganic hybrid solar cell. To produce CuFeS2 nanocomposite, hydrothermal strategy was employed. The room-temperature XRD pattern approves the synthesized material as CuFeS2 with no phase impurity (JCPDS Card no: 37-0471). The elemental composition of the material was analyzed from the TEM-EDX data. The obtained selected area electron diffraction (SAED) planes harmonized with the XRD pattern of the synthesized product. Optical band gap (4.14 eV) of the composite from UV-Vis analysis depicts that the synthesized material is belonging to wide band gap semiconductor family. The HOMO (- 6.97 eV) and LUMO (- 2.93 eV) positions from electrochemical study reveal that there is a possibility of electron transfer from MEH-PPV to CuFeS2. The optical absorption and photoluminescence spectra of MEH-PPV:CuFeS2 (donor:acceptor) composite were recorded sequentially by varying weight ratios. The monotonic blue shifting of the absorption peak position indicated the interaction between donor and acceptor materials. The possibility of electron transfer from donor (MEH-PPV) to acceptor (CuFeS2) was approved with photoluminescence analysis. Subsequently, we have fabricated a hybrid solar cell by incorporating CuFeS2 nanocomposite with MEH-PPV in open atmosphere and obtained 0.3% power conversion efficiency.

  10. Effect of donor to acceptor ratio on electrochemical and spectroscopic properties of oligoalkylthiophene 1,3,4-oxadiazole derivatives.

    Science.gov (United States)

    Kurowska, Aleksandra; Zassowski, Pawel; Kostyuchenko, Anastasia S; Zheleznova, Tatyana Yu; Andryukhova, Kseniya V; Fisyuk, Alexander S; Pron, Adam; Domagala, Wojciech

    2017-11-15

    A structure-property study across a series of donor-acceptor-donor structures composed of mono- and bi-(1,3,4-oxadiazole) units symmetrically substituted with alkyl functionalized bi-, ter- and quaterthiophene segments is presented. Synthetically tailoring the ratio of electron-withdrawing 1,3,4-oxadiazole to electron-releasing thiophene units and their alkyl grafting pattern permitted us to scrutinize the impact of these structural factors on the redox, absorptive and emissive properties of these push-pull molecules. Contrasting trends of redox potentials were observed, with the oxidation potential closely following the donor-to-acceptor ratio, whereas the reduction potential being tuned independently by either the number of acceptor units or the conjugation length of the donor-acceptor system. Increasing the thiophene unit contribution delivered a shift from blue to green luminescence, while the structural rigidity afforded by intramolecular non-covalent interactions between 1,3,4-oxadiazole and the thiophene moieties has been identified as the prime factor determining the emission efficiency of these molecules. All six structures investigated electro-polymerize easily, yielding electroactive and electrochromic polymers. The polymer doping process is largely influenced by the length of the oligothiophene repeating unit and the alkyl chain grafting density. Polymers with relatively short oligothiophene segments are able to support polarons and polaron-pairs, whereas those with segments longer than six thiophene units could also stabilize diamagnetic charge carries - bipolarons. Increasing the alkyl chain grafting density improved the reversibility and broadened the working potential window of the p-doping process. Stable radical anions have also been investigated, bringing detailed information about the conjugation pattern of these electron-surplus species. This study delivers interesting clues towards the conscious structural design of bespoke frontier energy

  11. Merocyanines: polyene-polymethine transition in donor-acceptor-substituted stilbenes and polyenes

    International Nuclear Information System (INIS)

    Rettig, Wolfgang; Dekhtyar, Marina

    2003-01-01

    Three series of donor-acceptor-substituted conjugated compounds, namely, stilbenes, the open-chain polyenes of equivalent length, and the species of intermediate structure (polyenes terminated with only one phenyl ring) have been studied by the AM1 and HMO methods to elucidate and compare the structural prerequisites of the ideal polymethinic state ('cyanine limit'). The transition from polyenic to polymethinic properties has been traced in terms of bond-length (bond-order) alternation using the variation of terminal donor and acceptor substituents. Stilbenes manifest themselves as notably 'retarded' polyenes since a larger electronic asymmetry is necessary for them to reach the same degree of polymethinic character. The ground and the excited state have been shown to differ much more strongly for stilbenes than for polyenes with respect to the position of the bond equalization point on the scale of donor-acceptor difference. For the compounds containing one phenyl ring, the features revealed are intermediate between stilbenes and polyenes. The large S 0 -S 1 discrepancy in terms of bond alternation is a general property of aromatic ring-terminated chains (stilbenes) and is related to the influence of the aromatic character which can be quantified in this way. In this context, the most relevant definition for the cyanine limit (based on the bond invariance upon excitation) was selected from the existing definitions. The major trends revealed in the polyenic/polymethinic behaviour of the molecules can be interpreted on a topological basis within HMO or even simpler models with some additional influence due to the interelectronic repulsion which is taken into account in the AM1 treatment

  12. Cyclic electron flow provides acclimatory plasticity for the photosynthetic machinery under various environmental conditions and developmental stages

    Directory of Open Access Journals (Sweden)

    Marjaana eSuorsa

    2015-09-01

    Full Text Available Photosynthetic electron flow operates in two modes, linear and cyclic. In cyclic electron flow (CEF, electrons are recycled around photosystem I. As a result, a transthylakoid proton gradient (ΔpH is generated, leading to the production of ATP without concomitant production of NADPH, thus increasing the ATP/NADPH ratio within the chloroplast. At least two routes for CEF exist: a PGR5-PGRL1–and a chloroplast NDH-like complex mediated pathway. This review focuses on recent findings concerning the characteristics of both CEF routes in higher plants, with special emphasis paid on the crucial role of CEF in under challenging environmental conditions and developmental stages.

  13. Stationary Conditions of the Electron Density Along the Reaction Path: Connection with Conceptual DFT and Information Theory.

    Science.gov (United States)

    Gonzalez, Carlos A; Squitieri, Emilio; Franco, Hector J; Rincon, Luis C

    2017-01-26

    The Kohn-Sham density functional theory (DFT) formalism has been used to investigate the influence of the stationary behavior of the electron density (ρ(r⃗;s)) along a minimum energy path on the corresponding stationary conditions observed in the total potential energy of the reactive system, information theory measures (Shannon information entropy and Onicescu information energy), and chemical reactivity indexes (the chemical hardness). The theoretical treatment presented in this work, combined with DFT calculations on 3 different test reactions: Ḣ' + H 2 , Ḣ' + CH 4 and H - + CH 4 , suggest that for any reactive system, properties that can be cast as a functional of the electron density, must exhibit stationary points along the IRC path modulated by the corresponding stationary behavior of the electron density.

  14. Electron transfer rates and equilibrium within cytochrome c oxidase

    DEFF Research Database (Denmark)

    Farver, O; Einarsdóttir, O; Pecht, I

    2000-01-01

    Intramolecular electron transfer (ET) between the CuA center and heme a in bovine cytochrome c oxidase was investigated by pulse radiolysis. CuA, the initial electron acceptor, was reduced by 1-methyl nicotinamide radicals in a diffusion-controlled reaction, as monitored by absorption changes...... s-1, respectively, at 25 degrees C and pH 7.4. This corresponds to an equilibrium constant of 3.4 under these conditions. Thermodynamic and activation parameters of the ET reactions were determined. The significance of these results, particularly the observed low activation barriers, are discussed...

  15. Cascade energy transfer and tunable emission from nanosheet hybrids: locating acceptor molecules through chiral doping.

    Science.gov (United States)

    Goudappagouda; Wakchaure, Vivek Chandrakant; Ranjeesh, Kayaramkodath Chandran; Abhai, Chalona Antony Ralph; Babu, Sukumaran Santhosh

    2017-06-27

    Light harvesting donor-acceptor assemblies are indispensable to efficiently tap photons. In an attempt to improve the light harvesting efficiency of an acceptor doped assembly, we design and synthesize a donor-acceptor-donor triad which exhibits an exceptional intramolecular energy transfer with excellent efficiency. Moreover, a facile cascade energy transfer (energy funnelling) is observed in the presence of a series of second acceptors (63-91% efficiency) with tunable emission colours. Self-assembled nanosheets formed by the triad in the presence of acceptors exhibit cascade energy transfer assisted tunable emission. In addition, use of chiral acceptors induces chirality to the triad and results in the formation of chiral nanosheets along with cascade energy transfer. Here chiral induction, nanosheet formation and cascade energy transfer in the presence of chiral acceptors are used as tools to probe the intercalation of acceptor molecules in the donor scaffold.

  16. The extreme condition analyzing for NEMPI shielding of electronic system in high-intensity pulsed radiation diagnosing

    International Nuclear Information System (INIS)

    Cheng Xiaolei; Liu Fang; Ouyang Xiaoping

    2012-01-01

    The difficulty for estimating the NEMPI (electromagnetic pulsed interference caused by the nuclear reaction) on the electronic system in high-intensity pulsed radiation diagnosing is analyzed in this article. To solve the difficulty, a method called 'Extreme Condition Analyzing' is presented for estimating the NEMPI conservatively and reliably. Through an extreme condition hypothesizing which could be described as 'Entire Coupling of Electric Field Energy', the E max (maximum electric field intensity which could be endured by the electronic system in the high-intensity pulsed radiation) could be figured out without any other information of the EMP caused by the nuclear reaction. Then a feasibility inspection is introduced, to confirm that the EMPI shielding request according to E max is not too extreme to be achieved. (authors)

  17. conditions

    Directory of Open Access Journals (Sweden)

    M. Venkatesulu

    1996-01-01

    Full Text Available Solutions of initial value problems associated with a pair of ordinary differential systems (L1,L2 defined on two adjacent intervals I1 and I2 and satisfying certain interface-spatial conditions at the common end (interface point are studied.

  18. Collisional Damping of Electron Bernstein Waves and its Mitigation by Evaporated Lithium Conditioning in Spherical-Tokamak Plasmas

    International Nuclear Information System (INIS)

    Diem, S. J.; Caughman, J. B.; Taylor, G.; Efthimion, P. C.; Kugel, H.; LeBlanc, B. P.; Phillips, C. K.; Preinhaelter, J.; Urban, J.; Sabbagh, S. A.

    2009-01-01

    The first experimental verification of electron Bernstein wave (EBW) collisional damping, and its mitigation by evaporated Li conditioning, in an overdense spherical-tokamak plasma has been observed in the National Spherical Torus Experiment (NSTX). Initial measurements of EBW emission, coupled from NSTX plasmas via double-mode conversion to O-mode waves, exhibited <10% transmission efficiencies. Simulations show 80% of the EBW energy is dissipated by collisions in the edge plasma. Li conditioning reduced the edge collision frequency by a factor of 3 and increased the fundamental EBW transmission to 60%.

  19. Structure of the channeling electrons wave functions under dynamical chaos conditions

    International Nuclear Information System (INIS)

    Shul’ga, N.F.; Syshchenko, V.V.; Tarnovsky, A.I.; Isupov, A.Yu.

    2016-01-01

    The stationary wave functions of fast electrons axially channeling in the silicon crystal near [1 1 0] direction have been found numerically for integrable and non-integrable cases, for which the classical motion is regular and chaotic, respectively. The nodal structure of the wave functions in the quasi-classical region, where the energy levels density is high, is agreed with quantum chaos theory predictions.

  20. Lipase-catalyzed biodiesel synthesis with different acyl acceptors

    Directory of Open Access Journals (Sweden)

    Ognjanović Nevena D.

    2008-01-01

    Full Text Available Biodiesel is an alternative fuel for diesel engine that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The aim of the present work was to investigate novel acyl acceptors for biodiesel production. 2-Propanol and n-butanol have a less negative effect on lipase stability, and they also improve low temperature properties of the fuel. However, excess alcohol leads to inactivation of the enzyme, and glycerol, a major byproduct, can block the immobilized enzyme, resulting in low enzymatic activity. This problem was solved by using methyl acetate as acyl acceptor. Triacetylglycerol is produced instead of glycerol, and it has no negative effect on the activity of the lipase.

  1. Benzene oxidation under sulfate-reducing conditions in columns simulating in situ conditions.

    Science.gov (United States)

    Vogt, Carsten; Gödeke, Stefan; Treutler, Hanns-Christian; Weiss, Holger; Schirmer, Mario; Richnow, Hans-Hermann

    2007-10-01

    The oxidation of benzene under sulfate-reducing conditions was examined in column and batch experiments under close to in situ conditions. Mass balances and degradation rates for benzene oxidation were determined in four sand and four lava granules filled columns percolated with groundwater from an anoxic benzene-contaminated aquifer. The stoichiometry of oxidized benzene, produced hydrogen carbonate and reduced sulfate correlated well with the theoretical equation for mineralization of benzene with sulfate as electron acceptor. Mean retention times of water in four columns were determined using radon ((222)Rn) as tracer. The retention times were used to calculate average benzene oxidation rates of 8-36 microM benzene day(-1). Benzene-degrading, sulfide-producing microcosms were successfully established from sand material of all sand filled columns, strongly indicating that the columns were colonized by anoxic benzene-degrading microorganisms. In general, these data indicate a high potential for Natural Attenuation of benzene under sulfate-reducing conditions at the field site Zeitz. In spite of this existing potential to degrade benzene with sulfate as electron acceptor, the benzene plume at the field site is much longer than expected if benzene would be degraded at the rates observed in the column experiment, indicating that benzene oxidation under sulfate-reducing conditions is limited in situ.

  2. Direct correlation of charge transfer absorption with molecular donor:acceptor interfacial area via photothermal deflection spectroscopy

    KAUST Repository

    Domingo, Ester

    2015-04-09

    We show that the Charge Transfer (CT) absorption signal in bulk-heterojunction (BHJ) solar cell blends, measured by photothermal deflection spectroscopy (PDS), is directly proportional to the density of molecular donor/acceptor interfaces. Since the optical transitions from ground state to the interfacial CT state are weakly allowed at photon energies below the optical gap of both donor and acceptor, we can exploit the use of this sensitive linear absorption spectroscopy for such quantification. Moreover, we determine the absolute molar extinction coefficient of the CT transition for an archetypical polymer-fullerene interface. The latter is ~100 times lower than the extinction coefficient of the donor chromophore involved, allowing us to experimentally estimate the transition dipole moment (0.3 D) and the electronic coupling between ground state and CT state to be on the order of 30 meV.

  3. Peptide-Driven Charge-Transfer Organogels Built from Synergetic Hydrogen Bonding and Pyrene-Naphthalenediimide Donor-Acceptor Interactions.

    Science.gov (United States)

    Bartocci, Silvia; Berrocal, José Augusto; Guarracino, Paola; Grillaud, Maxime; Franco, Lorenzo; Mba, Miriam

    2018-02-26

    The peptide-driven formation of charge transfer (CT) supramolecular gels featuring both directional hydrogen-bonding and donor-acceptor (D-A) complexation is reported. Our design consists of the coassembly of two dipeptide-chromophore conjugates, namely diphenylalanine (FF) dipeptide conveniently functionalized at the N-terminus with either a pyrene (Py-1, donor) or naphthalene diimide (NDI-1, acceptor). UV/Vis spectroscopy confirmed the formation of CT complexes. FTIR and 1 H NMR spectroscopy studies underlined the pivotal role of hydrogen bonding in the gelation process, and electronic paramagnetic resonance (EPR) measurements unraveled the advantage of preorganized CT supramolecular architectures for charge transport over solutions containing non-coassembled D and A molecular systems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Novel rhodanine based molecular acceptor for organic solar cells

    Directory of Open Access Journals (Sweden)

    Subianto Surya

    2017-01-01

    Full Text Available A dirhodanine-substituted benzothiadiazole compound has been synthesised using Knoevenagel condensation of a dialdehyde-substituted benzothiadiazole and rhodanine. The resulting compound was deep orange red in colour and shows a HOMO and LUMO levels of −5.61 and −3.85 eV respectively, which makes it suitable for applications such as acceptor for organic solar cells.

  5. Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

    Science.gov (United States)

    König, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

    2017-01-01

    All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusion, statistics of small numbers, quantum- or dielectric confinement. In analogy to the concept of modulation doping, originally invented for III-V semiconductors, we demonstrate a heterostructure modulation doping method for silicon. Our approach utilizes a specific acceptor state of aluminium atoms in silicon dioxide to generate holes as majority carriers in adjacent silicon. By relocating the dopants from silicon to silicon dioxide, Si nanoscale doping problems are circumvented. In addition, the concept of aluminium-induced acceptor states for passivating hole selective tunnelling contacts as required for high-efficiency photovoltaics is presented and corroborated by first carrier lifetime and tunnelling current measurements. PMID:28425460

  6. Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

    Science.gov (United States)

    König, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

    2017-04-01

    All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusion, statistics of small numbers, quantum- or dielectric confinement. In analogy to the concept of modulation doping, originally invented for III-V semiconductors, we demonstrate a heterostructure modulation doping method for silicon. Our approach utilizes a specific acceptor state of aluminium atoms in silicon dioxide to generate holes as majority carriers in adjacent silicon. By relocating the dopants from silicon to silicon dioxide, Si nanoscale doping problems are circumvented. In addition, the concept of aluminium-induced acceptor states for passivating hole selective tunnelling contacts as required for high-efficiency photovoltaics is presented and corroborated by first carrier lifetime and tunnelling current measurements.

  7. Income-generating activities for family planning acceptors.

    Science.gov (United States)

    1989-07-01

    The Income Generating Activities program for Family Planning Acceptors was introduced in Indonesia in 1979. Capital input by the Indonesian National Family Planning Coordination Board and the UN Fund for Population Activities was used to set up small businesses by family planning acceptors. In 2 years, when the businesses become self-sufficient, the loans are repaid, and the money is used to set up new family planning acceptors in business. The program strengthens family planning acceptance, improves the status of women, and enhances community self-reliance. The increase in household income generated by the program raises the standards of child nutrition, encourages reliance on the survival of children, and decreases the value of large families. Approximately 18,000 Family Planning-Income Generating Activities groups are now functioning all over Indonesia, with financial assistance from the central and local governments, the World Bank, the US Agency for International Development, the UN Population Fund, the Government of the Netherlands, and the Government of Australia through the Association of South East Asian Nations.

  8. Spectral, thermal and kinetic studies of charge-transfer complexes formed between the highly effective antibiotic drug metronidazole and two types of acceptors: σ- and π-acceptors

    Science.gov (United States)

    Refat, Moamen S.; Saad, Hosam A.; Adam, Abdel Majid A.

    2015-04-01

    Understanding the interaction between drugs and small inorganic or organic molecules is critical in being able to interpret the drug-receptor interactions and acting mechanism of these drugs. A combined solution and solid state study was performed to describe the complexation chemistry of drug metronidazole (MZ) which has a broad-spectrum antibacterial activity with two types of acceptors. The acceptors include, σ-acceptor (i.e., iodine) and π-acceptors (i.e., dichlorodicyanobenzoquinone (DDQ), chloranil (CHL) and picric acid (PA)). The molecular structure, spectroscopic characteristics, the binding modes as well as the thermal stability were deduced from IR, UV-vis, 1H NMR and thermal studies. The binding ratio of complexation (MZ: acceptor) was determined to be 1:2 for the iodine acceptor and 1:1 for the DDQ, CHL or PA acceptor, according to the CHN elemental analyses and spectrophotometric titrations. It has been found that the complexation with CHL and PA acceptors increases the values of enthalpy and entropy, while the complexation with DDQ and iodine acceptors decreases the values of these parameters compared with the free MZ donor.

  9. Soft x-ray free electron laser microfocus for exploring matter under extreme conditions

    Czech Academy of Sciences Publication Activity Database

    Nelson, A.J.; Toleikis, S.; Chapman, H.; Bajt, S.; Krzywinski, J.; Chalupský, Jaromír; Juha, Libor; Cihelka, Jaroslav; Hájková, Věra; Vyšín, Luděk; Burian, T.; Kozlová, Michaela; Fäustlin, R.R.; Nagler, B.; Vinko, S.M.; Whitcher, T.; Dzelzainis, T.; Renner, Oldřich; Saksl, K.; Khorsand, A.R.; Heimann, P.A.; Sobierajski, R.; Klinger, D.; Jurek, M.; Pelka, J.; Iwan, B.; Andreasson, J.; Timneanu, N.; Fajardo, M.; Wark, J. S.; Riley, D.; Tschentscher, T.; Hajdu, J.; Lee, R. W.

    2009-01-01

    Roč. 17, č. 20 (2009), s. 18271-18278 ISSN 1094-4087 R&D Projects: GA AV ČR KAN300100702; GA MŠk LC510; GA MŠk(CZ) LC528; GA MŠk LA08024; GA AV ČR IAAX00100903; GA AV ČR IAA400100701 Institutional research plan: CEZ:AV0Z10100523 Keywords : microfocus * multilayer mirror * off-axis parabola * x-ray free-electron laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.278, year: 2009

  10. Experimental and theoretical study of electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Festa, Floriane

    2013-01-01

    Matter in extreme conditions belongs to Warm Dense Matter regime which lays between dense plasma regime and condensed matter. This regime is still not well known, indeed it is very complex to generate such plasma in the laboratory to get experimental data and validate models. The goal of this thesis is to study electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy. Experimentally aluminum has reached high densities and high temperatures, up to now unexplored. An X-ray source has also been generated to probe highly compressed aluminum. Two spectrometers have recorded aluminum absorption spectra and aluminum density and temperature conditions have been deduced thanks to optical diagnostics. Experimental spectra have been compared to ab initio spectra, calculated in the same conditions. The theoretical goal was to validate the calculation method in high densities and high temperatures regime with the study of K-edge absorption modifications. We also used absorption spectra to study the metal-non metal transition which takes place at low density (density ≤ solid density). This transition could be study with electronic structure modifications of the system. (author) [fr

  11. Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

    Directory of Open Access Journals (Sweden)

    Forrest S. Etheridge

    2016-08-01

    Full Text Available Homoleptic zinc(II complexes of di(phenylacetyleneazadipyrromethene (e.g., Zn(WS32 are potential non-fullerene electron acceptors for organic photovoltaics. To tune their properties, fluorination of Zn(WS32 at various positions was investigated. Three fluorinated azadipyrromethene-based ligands were synthesized with fluorine at the para-position of the proximal and distal phenyl groups, and at the pyrrolic phenylacetylene moieties. Additionally, a CF3 moiety was added to the pyrrolic phenyl positions to study the effects of a stronger electron withdrawing unit at that position. The four ligands were chelated with zinc(II and BF2+ and the optical and electrochemical properties were studied. Fluorination had little effect on the optical properties of both the zinc(II and BF2+ complexes, with λmax in solution around 755 nm and 785 nm, and high molar absorptivities of 100 × 103 M−1cm−1 and 50 × 103 M−1cm−1, respectively. Fluorination of Zn(WS32 raised the oxidation potentials by 0.04 V to 0.10 V, and the reduction potentials by 0.01 V to 0.10 V, depending on the position and type of substitution. The largest change was observed for fluorine substitution at the proximal phenyl groups and CF3 substitution at the pyrrolic phenylacetylene moieties. The later complexes are expected to be stronger electron acceptors than Zn(WS32, and may enable charge transfer from other conjugated polymer donors that have lower energy levels than poly(3-hexylthiophene (P3HT.

  12. Experimental investigation of activities and tolerance of denitrifying bacteria under alkaline and reducing condition

    International Nuclear Information System (INIS)

    Mine, Tatsuya; Mihara, Morihiro; Ooi, Takao

    2000-07-01

    In the geological disposal system of TRU wastes, nitrogen generation by denitrifying bacteria could provide significant impact on the assessment of this system, because nitrate contained in process concentrated liquid waste might be electron acceptor for denitrifying bacteria. In this study, the activities and tolerance of denitrifying under disposal condition were investigated. Pseudomonas denitrificans as denitrifying bacteria was used. The results showed that Pseudomonas denitrificans had activity under reducing condition, but under high pH condition (pH>9.5), the activity of Pseudomonas denitrificans was not detected. It is possible that the activity of Pseudomonas denitrificans would be low under disposal condition. (author)

  13. Charge Carrier Dynamics at Silver Nanocluster-Molecular Acceptor Interfaces

    KAUST Repository

    Almansaf, Abdulkhaleq

    2017-07-01

    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

  14. 76 FR 55293 - Special Conditions: Diamond Aircraft Industries, Model DA-40NG; Electronic Engine Control (EEC...

    Science.gov (United States)

    2011-09-07

    ... interfaces. Additionally, special conditions for High Intensity Radiated Fields (HIRF) were also applied... for Sec. 23.1309 and propulsion system capabilities and failure susceptibilities. The following figure... loss. capabilities or capabilities or capabilities or capabilities or safety. safety margins. safety...

  15. 76 FR 31456 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Flight Control System: Control...

    Science.gov (United States)

    2011-06-01

    ... the noise certification requirements of 14 CFR part 36. The FAA must also issue a finding of regulatory adequacy pursuant to section 611 of Public Law 92-574, the ``Noise Control Act of 1972.'' The FAA... awareness and avoiding undesirable nuisance warnings. This special condition establishes a level of safety...

  16. 76 FR 9265 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Flight Control System: Control...

    Science.gov (United States)

    2011-02-17

    ... the noise certification requirements of 14 CFR part 36. The FAA must also issue a finding of regulatory adequacy pursuant to section 611 of Public Law 92-574, the ``Noise Control Act of 1972.'' The FAA... crew awareness and avoiding undesirable nuisance warnings. This proposed special condition would...

  17. 78 FR 75453 - Special Conditions: Cessna Model 750 Series Airplanes; Aircraft Electronic System Security...

    Science.gov (United States)

    2013-12-12

    ... FAA therefore finds that good cause exists for making these special conditions effective upon... design integration may result in security vulnerabilities from intentional or unintentional corruption of... historically proprietary. Therefore, they are not as susceptible to corruption from worms, viruses, and other...

  18. 78 FR 73995 - Special Conditions: Cessna Model 680 Series Airplanes; Aircraft Electronic System Security...

    Science.gov (United States)

    2013-12-10

    ... received. The FAA therefore finds that good cause exists for making these special conditions effective upon... may result in security vulnerabilities from intentional or unintentional corruption of data and... historically proprietary. Therefore, they are not as susceptible to corruption from worms, viruses, and other...

  19. Detection and mapping of trace explosives on surfaces under ambient conditions using multiphoton electron extraction spectroscopy (MEES).

    Science.gov (United States)

    Tang, Shisong; Vinerot, Nataly; Fisher, Danny; Bulatov, Valery; Yavetz-Chen, Yehuda; Schechter, Israel

    2016-08-01

    Multiphoton electron extraction spectroscopy (MEES) is an analytical method in which UV laser pulses are utilized for extracting electrons from solid surfaces in multiphoton processes under ambient conditions. Counting the emitted electrons as a function of laser wavelength results in detailed spectral features, which can be used for material identification. The method has been applied to detection of trace explosives on a variety of surfaces. Detection was possible on dusty swabs spiked with explosives and also in the standard dry-transfer contamination procedure. Plastic explosives could also be detected. The analytical limits of detection (LODs) are in the sub pmole range, which indicates that MEES is one of the most sensitive detection methods for solid surface under ambient conditions. Scanning the surface with the laser allows for its imaging, such that explosives (as well as other materials) can be located. The imaging mode is also useful in forensic applications, such as detection of explosives in human fingerprints. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Additive-Morphology Interplay and Loss Channels in “All-Small-Molecule” Bulk-heterojunction (BHJ) Solar Cells with the Nonfullerene Acceptor IDTTBM

    KAUST Repository

    Liang, Ru-Ze

    2017-12-16

    Achieving efficient bulk-heterojunction (BHJ) solar cells from blends of solution-processable small-molecule (SM) donors and acceptors is proved particularly challenging due to the complexity in obtaining a favorable donor–acceptor morphology. In this report, the BHJ device performance pattern of a set of analogous, well-defined SM donors—DR3TBDTT (DR3), SMPV1, and BTR—used in conjunction with the SM acceptor IDTTBM is examined. Examinations show that the nonfullerene “All-SM” BHJ solar cells made with DR3 and IDTTBM can achieve power conversion efficiencies (PCEs) of up to ≈4.5% (avg. 4.0%) when the solution-processing additive 1,8-diiodooctane (DIO, 0.8% v/v) is used in the blend solutions. The figures of merit of optimized DR3:IDTTBM solar cells contrast with those of “as-cast” BHJ devices from which only modest PCEs <1% can be achieved. Combining electron energy loss spectrum analyses in scanning transmission electron microscopy mode, carrier transport measurements via “metal-insulator-semiconductor carrier extraction” methods, and systematic recombination examinations by light-dependence and transient photocurrent analyses, it is shown that DIO plays a determining role—establishing a favorable lengthscale for the phase-separated SM donor–acceptor network and, in turn, improving the balance in hole/electron mobilities and the carrier collection efficiencies overall.

  1. Electronic health records and online medical records: an asset or a liability under current conditions?

    Science.gov (United States)

    Allen-Graham, Judith; Mitchell, Lauren; Heriot, Natalie; Armani, Roksana; Langton, David; Levinson, Michele; Young, Alan; Smith, Julian A; Kotsimbos, Tom; Wilson, John W

    2018-02-01

    Objective The aim of the present study was to audit the current use of medical records to determine completeness and concordance with other sources of medical information. Methods Medical records for 40 patients from each of five Melbourne major metropolitan hospitals were randomly selected (n=200). A quantitative audit was performed for detailed patient information and medical record keeping, as well as data collection, storage and utilisation. Using each hospital's current online clinical database, scanned files and paperwork available for each patient audited, the reviewers sourced as much relevant information as possible within a 30-min time allocation from both the record and the discharge summary. Results Of all medical records audited, 82% contained medical and surgical history, allergy information and patient demographics. All audited discharge summaries lacked at least one of the following: demographics, medication allergies, medical and surgical history, medications and adverse drug event information. Only 49% of records audited showed evidence the discharge summary was sent outside the institution. Conclusions The quality of medical data captured and information management is variable across hospitals. It is recommended that medical history documentation guidelines and standardised discharge summaries be implemented in Australian healthcare services. What is known about this topic? Australia has a complex health system, the government has approved funding to develop a universal online electronic medical record system and is currently trialling this in an opt-out style in the Napean Blue Mountains (NSW) and in Northern Queensland. The system was originally named the personally controlled electronic health record but has since been changed to MyHealth Record (2016). In Victoria, there exists a wide range of electronic health records used to varying degrees, with some hospitals still relying on paper-based records and many using scanned medical records

  2. The effect of intramolecular donor–acceptor moieties with donor–π-bridge–acceptor structure on the solar photovoltaic performance

    Directory of Open Access Journals (Sweden)

    T. L. Wang

    2015-10-01

    Full Text Available A series of intramolecular donor–acceptor polymers containing different contents of (E-1-(2-ethylhexyl-6,9-dioctyl-2-(2-(thiophen-3-ylvinyl-1H-phenanthro[9,10-d]imidazole (thiophene-DOPI moiety and 4,4-diethylhexylcyclopenta[ 2,1-b:3,4-b']dithiophene (CPDT unit was synthesized via Grignard metathesis (GRIM polymerization. The synthesized random copolymers and homopolymer of thiophene-DOPI contain the donor–π-bridge–acceptor conjugated structure to tune the absorption spectra and energy levels of the resultant polymers. UV-vis spectra of the three polymer films exhibit panchromatic absorptions ranging from 300 to 1100 nm and low band gaps from 1.38 to 1.51 eV. It is found that more thiophene-DOPI moieties result in the decrease of band gap and lower the highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO values of polymers. Photovoltaic performance results indicate that if the content of the intramolecular donor–acceptor moiety is high enough, the copolymer structure may be better than homopolymer due to more light-harvesting afforded by both monomer units.

  3. Improving Working Conditions for Astronauts: An Electronic Personal Restraint System for Use in Microgravity Environments

    Directory of Open Access Journals (Sweden)

    Kevin Tait

    2012-01-01

    Full Text Available While in microgravity, astronauts are preoccupied with physical restraint, which takes attention away from the maintenance task or scientific experiment at hand. This may directly lead to safety concerns and increased time for extravehicular activity, as well as potentially inhibit or corrupt data collection. A primary concern is the time it takes to manipulate the current restraint system. The portable foot restraint currently in use by NASA employs a series of pins in order to engage the system or release in an emergency. This requires considerable time for the user to detach, and there is an increased risk of entanglement. If restraint operating time could be reduced by 50%, the astronaut’s assigned experiment time could be increased an average of 100 minutes per mission. Another problem identified by NASA included the inability of the current system to release the user upon failure. Research and design was conducted following the Six-Sigma DMEDI project architecture, and a new form of restraint to replace the existing system was proposed. The research team first studied the customer requirements and relevant standards set by NASA, and with this information they began drafting designs for a solution. This project utilized electromagnetism to restrain a user in microgravity. The proposed system was capable of being manipulated quickly, failing in a manner that released the user, and being electronically controlled. This active electronic control was a new concept in restraint systems, as it enabled an astronaut to effectively “walk” along a surface while remaining restrained to it. With the design prototype and a limited budget, a rudimentary test assembly was built by the team, and most of NASA’s specifications were met. With recommendations from NASA, the research team concluded by developing potential material and design solutions that can be explored in the future by Purdue University or other parties.

  4. The role of deep acceptor centers in the oxidation of acceptor-doped wide-band-gap perovskites ABO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Putilov, L.P., E-mail: lev.putilov@gmail.com; Tsidilkovski, V.I.

    2017-03-15

    The impact of deep acceptor centers on defect thermodynamics and oxidation of wide-band-gap acceptor-doped perovskites without mixed-valence cations is studied. These deep centers are formed by the acceptor-bound small hole polarons whose stabilization energy can be high enough (significantly higher than the hole-acceptor Coulomb interaction energy). It is shown that the oxidation enthalpy ΔH{sub ox} of oxide is determined by the energy ε{sub A} of acceptor-bound states along with the formation energy E{sub V} of oxygen vacancies. The oxidation reaction is demonstrated to be either endothermic or exothermic, and the regions of ε{sub A} and E{sub V} values corresponding to the positive or negative ΔH{sub ox} are determined. The contribution of acceptor-bound holes to the defect thermodynamics strongly depends on the acceptor states depth ε{sub A}: it becomes negligible at ε{sub A} less than a certain value (at which the acceptor levels are still deep). With increasing ε{sub A}, the concentration of acceptor-bound small hole polarons can reach the values comparable to the dopant content. The results are illustrated with the acceptor-doped BaZrO{sub 3} as an example. It is shown that the experimental data on the bulk hole conductivity of barium zirconate can be described both in the band transport model and in the model of hopping small polarons localized on oxygen ions away from the acceptor centers. Depending on the ε{sub A} magnitude, the oxidation reaction can be either endothermic or exothermic for both mobility mechanisms.

  5. Biotransformation of monoaromatic hydrocarbons under anoxic conditions

    International Nuclear Information System (INIS)

    Ball, H.A.; Reinhard, M.; McCarty, P.L.

    1991-01-01

    Aromatic hydrocarbons contained in gasoline are environmental pollutants of particular concern since they are relatively soluble in water, many are toxic, and some are confirmed carcinogens, (e.g., benzene). Although most gasoline constituents are readily degraded in aerobic surface water systems, the groundwater environment associated with hydrocarbon spills is typically anaerobic, thus precluding aerobic degradation pathways. In the absence of oxygen, degradation of gasoline components can take place only with the utilization of alternate electron acceptors such as nitrate, sulfate, carbon dioxide, and possibly ferric iron or other metal oxides. Benzene, toluene, and xylene isomers were completely degraded by aquifer- or sewage sludge-derived microorganisms under dentrifying and methanogenic conditions. Recently, a pure culture was found to degrade toluene and m-xylene nitrate or nitrous oxide as an electron acceptor. This paper presents initial results of ongoing study to develop and characterize microbial consortia capable of transforming aromatic hydrocarbons under nitrate-reducing conditions, and understand the effect of environmental factors on the biotransformation processes

  6. Optimized calculation of the synergy conditions between electron cyclotron current drive and lower hybrid current drive on EAST

    International Nuclear Information System (INIS)

    Wei Wei; Ding Bo-Jiang; Li Miao-Hui; Zhang Xin-Jun; Wang Xiao-Jie; Peysson, Y; Decker, J; Zhang Lei

    2016-01-01

    The optimized synergy conditions between electron cyclotron current drive (ECCD) and lower hybrid current drive (LHCD) with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on the understanding of the synergy mechanisms so as to obtain a higher synergistic current and provide theoretical reference for the synergistic effect in the EAST experiment. The dependences of the synergistic effect on the parameters of two waves (lower hybrid wave (LHW) and electron cyclotron wave (ECW)), including the radial position of the power deposition, the power value of the LH and EC waves, and the parallel refractive indices of the LHW (N ∥ ) are presented and discussed. (paper)

  7. The Non-Equilibrium Statistical Distribution Function for Electrons and Holes in Semiconductor Heterostructures in Steady-State Conditions

    Directory of Open Access Journals (Sweden)

    Krzysztof Jόzwikowska

    2015-06-01

    Full Text Available The main goal of this work is to determine a statistical non-equilibrium distribution function for the electron and holes in semiconductor heterostructures in steady-state conditions. Based on the postulates of local equilibrium, as well as on the integral form of the weighted Gyarmati’s variational principle in the force representation, using an alternative method, we have derived general expressions, which have the form of the Fermi–Dirac distribution function with four additional components. The physical interpretation of these components has been carried out in this paper. Some numerical results of a non-equilibrium distribution function for an electron in HgCdTe structures are also presented.

  8. Working conditions and environmental exposures among electronic waste workers in Ghana.

    Science.gov (United States)

    Akormedi, Matthew; Asampong, Emmanuel; Fobil, Julius N

    2013-01-01

    To investigate and describe informal e-waste recycling and working conditions at Agbogbloshie, Accra, Ghana. We conducted in-depth interviews which were qualitatively analysed from a grounded theory perspective. Workers obtained e-waste from the various residential areas in Accra, then dismantled and burned them in open air to recover copper, aluminum, steel, and other products for sale to customers on-site or at the nearby Agbogbloshie market. The processers worked under unhealthy conditions often surrounded by refuse and human excreta without any form of protective gear and were thus exposed to frequent burns, cuts, and inhalation of highly contaminated fumes. We observed no form of social security/support system for the workers, who formed informal associations to support one another in times of difficulty. e-waste recycling working conditions were very challenging and presented serious hazards to worker health and wellbeing. Formalizing the e-waste processing activities requires developing a framework of sustainable financial and social security for the e-waste workers, including adoption of low-cost, socially acceptable, easy-to-operate, and cleaner technologies that would safeguard the health of the workers and the general public.

  9. Electron precipitation events in the lower ionosphere and the geospace conditions

    Directory of Open Access Journals (Sweden)

    José Henrique Fernandez

    2013-06-01

    Full Text Available We present an analysis of localized ionospheric perturbations detected at Comandante Ferraz Brazilian Antarctic Station (McIlwain parameter L~2.25 as fast-amplitude variations of very low frequency (VLF signals transmitted from Hawaii (NPM, at 21.4 kHz, also known as Trimpi events. The study covers the first six months of 2007, during the period of minimum activity in the 23rd solar cycle. The occurrence of Trimpi events in the Antarctica peninsula region was studied in association with solar-wind parameters in the neighborhood of the Earth (geospace, along with the geomagnetic activity level (Ap, Dst indices. The analysis shows that the Trimpi events occurred predominantly during geomagnetically disturbed periods, but they have a more intricate association with the geospace regimes. The events achieve higher occurrence during the recovery phase of some geomagnetic storms, and also show a close association with electron flux enhancements in the belt region, especially those with higher energy. The higher event incidence occurred a few hours after what we call the 'angle bracket' phenomenon: when the solar wind velocity rises simultaneous with a decrease in its density.

  10. Permanent magnet electron beam ion source/trap systems with bakeable magnets for improved operation conditions.

    Science.gov (United States)

    Schmidt, M; Zschornack, G; Kentsch, U; Ritter, E

    2014-02-01

    The magnetic system of a Dresden electron beam ion source (EBIS) generating the necessary magnetic field with a new type of permanent magnet made of high energy density NdFeB-type material operable at temperatures above 100 °C has been investigated and tested. The employment of such kind of magnets provides simplified operation without the time-consuming installation and de-installation procedures of the magnets for the necessary baking of the ion source after commissioning and maintenance work. Furthermore, with the use of a new magnetization technique the geometrical filling factor of the magnetic Dresden EBIS design could be increased to a filling factor of 100% leading to an axial magnetic field strength of approximately 0.5 T exceeding the old design by 20%. Simulations using the finite element method software Field Precision and their results compared with measurements are presented as well. It could be shown that several baking cycles at temperatures higher than 100 °C did not change the magnetic properties of the setup.

  11. Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor–Acceptor Conjugated Polymers

    KAUST Repository

    Ayzner, Alexander L.

    2015-12-30

    © 2015 American Chemical Society. Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

  12. Contorted Organic Semiconductors for Molecular Electronics

    Science.gov (United States)

    Zhong, Yu

    This thesis focuses on the synthesis, properties and applications of two types of contorted organic molecules: contorted molecular ribbons and conjugated corrals. We utilized the power of reaction chemistry to writing information into conjugated molecules with contorted structures and studied "structure-property" relationships. The unique properties of the molecules were expressed in electronic and optoelectronic devices such as field-effect transistors, solar cells, photodetectors, etc. In Chapter 2, I describe the design and synthesis of a new graphene ribbon architecture that consists of perylenediimide (PDI) subunits fused together by ethylene bridges. We created a prototype series of oligomers consisting of the dimer, trimer, and tetramer. The steric congestion at the fusion point between the PDI units creates helical junctions, and longer oligomers form helical ribbons. Thin films of these oligomers form the active layer in n-type field effect transistors. UV-vis spectroscopy reveals the emergence of an intense long-wavelength transition in the tetramer. From DFT calculations, we find that the HOMO-2 to LUMO transition is isoenergetic with the HOMO to LUMO transition in the tetramer. We probe these transitions directly using femtosecond transient absorption spectroscopy. The HOMO-2 to LUMO transition electronically connects the PDI subunits with the ethylene bridges, and its energy depends on the length of the oligomer. In Chapter 3, I describe an efficiency of 6.1% for a solution processed non-fullerene solar cell using a helical PDI dimer as the electron acceptor. Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces, indicating that charge carriers are created from photogenerated excitons in both the electron donor and acceptor phases. Light-intensity-dependent current?voltage measurements suggested different recombination rates under short-circuit and open-circuit conditions. In

  13. NAD(P)H:(Quinone-Acceptor) Oxidoreductase of Tobacco Leaves Is a Flavin Mononucleotide-Containing Flavoenzyme.

    Science.gov (United States)

    Sparla, F.; Tedeschi, G.; Trost, P.

    1996-09-01

    The soluble NAD(P)H:(quinone-acceptor) oxidoreductase [NAD(P)H-QR, EC 1.6.99.2] of Nicotiana tabacum L. leaves and roots has been purified. NAD(P)H-QR contains noncovalently bound flavin mononucleotide. Pairs of subunits of 21.4 kD are linked together by disulfide bridges, but the active enzyme is a homotetramer of 94 to 100 kD showing an isoelectric point of 5.1. NAD(P)H-QR is a B-stereospecific dehydrogenase. NADH and NADPH are electron donors of similar efficiency with Kcat:Km ratios (with duroquinone) of 6.2 x 107 and 8.0 x 107 m-1 s-1, respectively. Hydrophilic quinones are good electron acceptors, although ferricyanide and dichlorophenolindophenol are also reduced. The quinones are converted to hydroquinones by an obligatory two-electron transfer. No spectral evidence for a flavin semiquinone was detected following anaerobic photoreduction. Cibacron blue and 7-iodo-acridone-4-carboxylic acid are inhibitory. Tobacco NAD(P)H-QR resembles animal DT-diaphorase in some respects (identical reaction mechanism with a two-electron transfer to quinones, unusually high catalytic capability, and donor and acceptor substrate specificity), but it differs from DT-diaphorase in molecular structure, flavin cofactor, stereospecificity, and sensitivity to inhibitors. As in the case with DT-diaphorase in animals, the main NAD(P)H-QR function in plant cells may be the reduction of quinones to quinols, which prevents the production of semiquinones and oxygen radicals. The enzyme appears to belong to a widespread group of plant and fungal flavoproteins found in different cell compartments that are able to reduce quinones.

  14. Electron transfer of monovalent cadmium

    International Nuclear Information System (INIS)

    Lerat-Parizot, O.; Potier, J.; Hickel, B.

    1993-01-01

    The surveys presented here concern monovalent Cadmium in aqueous solutions, produced by reduction of Cd(II), using pulsed radiolysis. We specifically studied the Cd(I) reactivity when complexed in certain synthetic ionophores. Cd(I), being an extremely powerful reducing agent, regains its stable valence by transferring an electron to an acceptor. Organic molecules are introduced into a solvent, permitting the analysis of the transfer rate of this electron. We investigated the influence of the ligand specificities and the variation of the electron transfer rate, that depend on the potential difference between Cadmium and the acceptor being used. 34 refs

  15. ESR identification of the nitrogen acceptor in 2H-polytype synthetic MoS2: Dopant level and activation

    Directory of Open Access Journals (Sweden)

    B. Schoenaers

    2017-10-01

    Full Text Available Multi-frequency electron spin resonance (ESR study of p-type synthetic 2H MoS2 reveals a previously unreported signal of axial-symmetry [g// = 2.032(2; g⊥ = 2.270(2] characteristic for a hole-type center in MoS2. It is identified as originating from N acceptor dopants, the N atoms substituting for S sites, with a density of ∼2.3 x 1017 cm-3, thus predominantly accounting for the p-type sample doping. For the applied magnetic field along the c-axis, the signal is mainly comprised of a 14N hyperfine 1:1:1 triplet of splitting A// = 14.7 ± 0.2 G with, on top, a center line accounting for ∼26% of the total signal intensity. The additional observation of a weak half-field signal (g = 3.92 correlating with the main full-field Zeeman response points to the presence of spin S ≥ 1 N agglomerates. The overall signal properties indicate that only ∼74% of the N acceptors occur as isolated decoupled dopants. Monitoring of the ESR signal intensity over a broad temperature range unveils the N dopant as a shallow acceptor of activation energy Ea = 45 ± 7 meV, thus well fit for stable substitutional p-type doping in MoS2-based novel nanoelectronic devices.

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

    International Nuclear Information System (INIS)

    Chin, Ken K.

    2011-01-01

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

  17. Thieno[3,2-b]pyrrolo-Fused Pentacyclic Benzotriazole-Based Acceptor for Efficient Organic Photovoltaics.

    Science.gov (United States)

    Feng, Liuliu; Yuan, Jun; Zhang, Zhenzhen; Peng, Hongjian; Zhang, Zhi-Guo; Xu, Shutao; Liu, Ye; Li, Yongfang; Zou, Yingping

    2017-09-20

    A novel nonfullerene small molecular acceptor (BZIC) based on a ladder-type thieno[3,2-b]pyrrolo-fused pentacyclic benzotriazole core (dithieno[3,2-b]pyrrolobenzotriazole, BZTP) and end-capped with 1,1-dicyanomethylene-3-indanone (INCN) has been first reported in this work. Through introducing multifused benzotriazole and INCN, BZIC could maintain a high-lying lowest unoccupied molecular orbital (LUMO) energy level of -3.88 eV. Moreover, BZIC shows a low optical bandgap of 1.45 eV with broad and efficient absorption band from 600 to 850 nm due to increased π-π interactions by the covalently locking thiophene and benzotriazole units. A power conversion efficiency of 6.30% is delivered using BZIC as nonfullerene acceptor and our recently synthesized hexafluoroquinoxaline-based polymer HFQx-T as donor. This is the first time to synthesize mutifused benzotriazole-based molecules as nonfullerene electron acceptor up to date. The preliminary results demonstrate that the mutifused benzotriazole derivatives hold great potential for efficient photovoltaics.

  18. Molecular design of novel fullerene-based acceptors for enhancing the open circuit voltage in polymer solar cells

    Science.gov (United States)

    Tajbakhsh, Mahmood; Kariminasab, Mohaddeseh; Ganji, Masoud Darvish; Alinezhad, Heshmatollah

    2017-12-01

    Organic solar cells, especially bulk hetero-junction polymer solar cells (PSCs), are the most successful structures for applications in renewable energy. The dramatic improvement in the performance of PSCs has increased demand for new conjugated polymer donors and fullerene derivative acceptors. In the present study, quantum chemical calculations were performed for several representative fullerene derivatives in order to determine their frontier orbital energy levels and electronic structures, thereby helping to enhance their performance in PSC devices. We found correlations between the theoretical lowest unoccupied molecular orbital levels and electrophilicity index of various fullerenes with the experimental open circuit voltage of photovoltaic devices according to the poly(3-hexylthiophene) (P3HT):fullerene blend. The correlations between the structure and descriptors may facilitate screening of the best fullerene acceptor for the P3HT donor. Thus, we considered fullerenes with new functional groups and we predicted the output factors for the corresponding P3HT:fullerene blend devices. The results showed that fullerene derivatives based on thieno-o-quinodimethane-C60 with a methoxy group will have enhanced photovoltaic properties. Our results may facilitate the design of new fullerenes and the development of favorable acceptors for use in photovoltaic applications.

  19. Transformations of TNT and related aminotoluenes in groundwater aquifer slurries under different electron-accepting conditions.

    Science.gov (United States)

    Krumholz, L R; Li, J; Clarkson, W W; Wilber, G G; Suflita, J M

    1997-01-01

    The transport and fate of pollutants is often governed by both their tendency to sorb as well as their susceptibility to biodegradation. We have evaluated these parameters for 2,4,6-trinitrotoluene (TNT) and several biodegradation products. Slurries of aquifer sediment and groundwater depleted TNT at rates of 27, 7.7 and 5.9 microM day-1 under methanogenic, sulfate-reducing and nitrate-reducing conditions, respectively. Abiotic losses of TNT were determined in autoclaved controls. Abiotic TNT loss and subsequent transformation of the products was also observed. These transformations were especially important during the first step in the reduction of TNT. Subsequent abiotic reactions could account for all of the transformations observed in bottles which were initially nitrate-reducing. Other controls removed TNT reduction products at much slower rates than slurries containing live organisms. 2-Amino-4,6-dinitrotoluene was produced in all slurries but disappeared in methanogenic and in sulfate-reducing slurries within several weeks. This compound was converted to 2,4-diamino-6-nitrotoluene in all slurries with subsequent removal of the latter from methanogenic and sulfate-reducing slurries, while it persisted in autoclaved controls and in the nitrate-reducing slurries. Aquifer slurries incubated with either 2,4- or 2,6-diaminotoluene showed losses of these compounds relative to autoclaved controls under nitrate-reducing conditions but not under sulfate-reducing or methanogenic conditions. These latter compounds are important as reduced intermediates in the biodegradation of dinitrotoluenes and as industrial chemicals. In experiments to examine sorption, exposure to landfill sediment resulted in losses of approximately 15% of diaminotoluene isomers and 25% of aminodinitrotoluene isomers from initial solution concentrations within 24 h. Isotherms confirmed that the diaminotoluenes were least strongly sorbed and the amino-dinitrotoluenes most strongly sorbed to this

  20. Roll-coating fabrication of ITO-free flexible solar cells based on a non-fullerene small molecule acceptor

    DEFF Research Database (Denmark)

    Liu, Wenqing; Shi, Hangqi; Andersen, Thomas Rieks

    2015-01-01

    We report organic solar cells (OSCs) with non-fullerene small molecule acceptors (SMAs) prepared in large area via a roll coating process. We employ all solution-processed indium tin oxide (ITO)-free flexible substrates for inverted solar cells with a new SMA of F(DPP)(2)B-2. By utilizing poly(3......-hexylthiophene) as donor blended with F(DPP)(2)B-2 as acceptor, ITO-free large-area flexible SMA based OSCs were produced under ambient conditions with the use of slot-die coating and flexographic printing methods on a lab-scale compact roll-coater that is readily transferrable to roll-to-roll processing...

  1. FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in Synechocystis sp. PCC 6803 under CO2-limited conditions.

    Science.gov (United States)

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-02-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. © 2015 American Society of Plant Biologists. All Rights Reserved.

  2. Communication: Recovering the flat-plane condition in electronic structure theory at semi-local DFT cost

    Science.gov (United States)

    Bajaj, Akash; Janet, Jon Paul; Kulik, Heather J.

    2017-11-01

    The flat-plane condition is the union of two exact constraints in electronic structure theory: (i) energetic piecewise linearity with fractional electron removal or addition and (ii) invariant energetics with change in electron spin in a half filled orbital. Semi-local density functional theory (DFT) fails to recover the flat plane, exhibiting convex fractional charge errors (FCE) and concave fractional spin errors (FSE) that are related to delocalization and static correlation errors. We previously showed that DFT+U eliminates FCE but now demonstrate that, like other widely employed corrections (i.e., Hartree-Fock exchange), it worsens FSE. To find an alternative strategy, we examine the shape of semi-local DFT deviations from the exact flat plane and we find this shape to be remarkably consistent across ions and molecules. We introduce the judiciously modified DFT (jmDFT) approach, wherein corrections are constructed from few-parameter, low-order functional forms that fit the shape of semi-local DFT errors. We select one such physically intuitive form and incorporate it self-consistently to correct semi-local DFT. We demonstrate on model systems that jmDFT represents the first easy-to-implement, no-overhead approach to recovering the flat plane from semi-local DFT.

  3. The effects of various gate oxidation conditions on intrinsic and radiation-induced extrinsic charged defects and neutral electron traps

    International Nuclear Information System (INIS)

    Walters, M.; Reisman, A.

    1990-01-01

    In this paper the influence of the oxidation temperature, ambient atmosphere, and oxidation rate on intrinsic and Al Kα x-ray radiation-induced extrinsic gate oxide defect levels in insulated-gate field effect transistors (IGFETs) is studied. Using optically assisted electron injection into n-channel polysilicon-gated IGFETs, neutral electron trap and fixed negative charge defect densities were measured, in addition to the fixed positive charge density. The results indicate that radiation-induced defect densities in the gate oxide decrease with increasing oxidation temperature in the 800 degrees C to 1000 degrees C range, and are lower for dry/wet/dry oxides than for dry oxides when the oxidation temperature is below 950 degrees C, but higher when the oxidation temperature is above 950 degrees C. The oxidation rate had no effect on defect levels in dry oxides grown at 1000 degrees CX, while at an oxidation temperature of 800 degrees C, the extrinsic defect densities were observed to increase when the oxidation rate was decreased. In all cases, the radiation-induced fixed positive charge and neutral electron trap defect densities were observed to be dependent upon the gate oxidation conditions in the same fashion

  4. Communication: Recovering the flat-plane condition in electronic structure theory at semi-local DFT cost.

    Science.gov (United States)

    Bajaj, Akash; Janet, Jon Paul; Kulik, Heather J

    2017-11-21

    The flat-plane condition is the union of two exact constraints in electronic structure theory: (i) energetic piecewise linearity with fractional electron removal or addition and (ii) invariant energetics with change in electron spin in a half filled orbital. Semi-local density functional theory (DFT) fails to recover the flat plane, exhibiting convex fractional charge errors (FCE) and concave fractional spin errors (FSE) that are related to delocalization and static correlation errors. We previously showed that DFT+U eliminates FCE but now demonstrate that, like other widely employed corrections (i.e., Hartree-Fock exchange), it worsens FSE. To find an alternative strategy, we examine the shape of semi-local DFT deviations from the exact flat plane and we find this shape to be remarkably consistent across ions and molecules. We introduce the judiciously modified DFT (jmDFT) approach, wherein corrections are constructed from few-parameter, low-order functional forms that fit the shape of semi-local DFT errors. We select one such physically intuitive form and incorporate it self-consistently to correct semi-local DFT. We demonstrate on model systems that jmDFT represents the first easy-to-implement, no-overhead approach to recovering the flat plane from semi-local DFT.

  5. An A-D-A'-D-A type small molecule acceptor with a broad absorption spectrum for organic solar cells.

    Science.gov (United States)

    Miao, Junhui; Meng, Bin; Liu, Jun; Wang, Lixiang

    2018-01-02

    Organic molecules with wide absorption spectra exhibit great sunlight harvesting capability and are critically important for solar cell applications. In this manuscript, we develop an A-D-A'-D-A type small molecule acceptor (IID-IC) using isoindigo (IID) as the electron-deficient core unit (A'), thiophene as the electron-rich bridging units (D) and 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) as the electron-deficient endcapping groups (A). IID-IC shows a wide absorption spectrum with the full width at half maximum (FWHM) of 190 nm, which is almost twice that of a typical A-D-A type molecule acceptor. The wide absorption spectrum of IID-IC is possibly due to the partially suppressed intramolecular charge transfer effect with the additional electron-deficient core unit. An organic solar cell (OSC) device based on IID-IC exhibits the power conversion efficiency of 2.82% with broad photoresponse from 320 nm to 780 nm.

  6. Design and Application of Variable Temperature Setup for Scanning Electron Microscopy in Gases and Liquids at Ambient Conditions.

    Science.gov (United States)

    Al-Asadi, Ahmed S; Zhang, Jie; Li, Jianbo; Potyrailo, Radislav A; Kolmakov, Andrei

    2015-06-01

    Scanning electron microscopy (SEM) of nanoscale objects in dry and fully hydrated conditions at different temperatures is of critical importance in revealing details of their interactions with an ambient environment. Currently available WETSEM capsules are equipped with thin electron-transparent membranes and allow imaging of samples at atmospheric pressure, but do not provide temperature control over the sample. Here, we developed and tested a thermoelectric cooling/heating setup for WETSEM capsules to allow ambient pressure in situ SEM studies with a temperature range between -15 and 100°C in gaseous, liquid, and frozen conditions. The design of the setup also allows for correlation of the SEM with optical microscopy and spectroscopy. As a demonstration of the possibilities of the developed approach, we performed real-time in situ microscopy studies of water condensation on a surface of Morpho sulkowskyi butterfly wing scales. We observed that initial water nucleation takes place on top of the scale ridges. These results confirmed earlier discovery of a preexisting polarity gradient of the ridges of Morpho butterflies. Our developed thermoelectric cooling/heating setup for environmental capsules meets the diverse needs for in situ nanocharacterization in material science, catalysis, microelectronics, chemistry, and biology.

  7. Frequency dependent dynamical electromechanical response of mixed ionic-electronic conductors

    Science.gov (United States)

    Morozovska, A. N.; Eliseev, E. A.; Bravina, S. L.; Ciucci, Francesco; Svechnikov, G. S.; Chen, Long-Qing; Kalinin, S. V.

    2012-01-01

    Frequency dependent dynamic electromechanical response of the mixed ionic-electronic conductor film to a periodic electric bias is analyzed for different electronic and ionic boundary conditions. Dynamic effects of mobile ions concentration (stoichiometry contribution), charge state of acceptors (donors), electron concentration (electron-phonon coupling via the deformation potential), and flexoelectric effect contribution are discussed. A variety of possible nonlinear dynamic electromechanical responses of mixed electronic ionic conductors (MIEC) films including quasi-elliptic curves, asymmetric hysteresis-like loops with pronounced memory window, and butterfly-like curves are calculated. The electromechanical response of ionic semiconductor is predicted to be a powerful descriptor of local valence states, band structure and electron-phonon correlations thatcan be readily measured in the nanoscale volumes and in the presence of strong electronic conductivity.

  8. Donor-Acceptor Chromophores based on Acetylenic Scaffolds and Indenofluorenes

    DEFF Research Database (Denmark)

    Christensen, Mikkel Andreas

    The work described in this thesis has been focused on synthesizing donor-acceptor chromophores with conjugated π-bridges. It has also led to the development of an alternative synthetic tool for acetylenic scaffolding. The first chapter focuses on the nitrophenol D-π-A system – A phenol in conjuga......The work described in this thesis has been focused on synthesizing donor-acceptor chromophores with conjugated π-bridges. It has also led to the development of an alternative synthetic tool for acetylenic scaffolding. The first chapter focuses on the nitrophenol D-π-A system – A phenol...... in conjugation with a nitrobenzene unit. Five nitrophenols were synthesized with different π-bridges covering the features of cross-conjugation, linear conjugation, planarity, and non-planarity. I was hoping to elucidate the intrinsic properties of the π-bridges via comparison of the charge-transfer absorptions...... of the compounds. The measurements in solution led to the conclusion that some of the transitions observed may not be charge-transfer transitions, as they were not red-shifted upon deprotonation of the phenol. The results can hopefully be used in combination with future measurements in the gas phase by our...

  9. Influence of annealing and interfacial roughness on the performance of bilayer donor/acceptor polymer photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hongping; Swaraj, Sufal; Wang, Cheng; Ade, Harald [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Hwang, Inchan; Greenham, Neil C.; McNeill, Christopher R. [Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Ave, Cambridge, CB3 0HE (United Kingdom); Groves, Chris [School of Engineering and Computing Sciences, Durham University, Durham, DH1 3LE (United Kingdom)

    2010-12-21

    Through controlled annealing of planar heterojunction (bilayer) devices based on the polyfluorene copolymers poly(9,9-dioctylfluorene-co-bis(N,N'-(4,butylphenyl))bis(N,N'-phenyl-1,4-phenylene)diamine) (PFB) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) we study the influence of interface roughness on the generation and separation of electron-hole pairs at the donor/acceptor interface. Interface structure is independently characterized by resonant soft X-ray reflectivity with the interfacial width of the PFB/F8BT heterojunction observed to systematically increase with annealing temperature from 1.6 nm for unannealed films to 16 nm with annealing at 200 C for ten minutes. Photoluminescence quenching measurements confirm the increase in interface area by the three-fold increase in the number of excitons dissociated. Under short-circuit conditions, however, unannealed devices with the sharpest interface are found to give the best device performance, despite the increase in interfacial area (and hence the number of excitons dissociated) in annealed devices. The decrease in device efficiency with annealing is attributed to decreased interfacial charge separation efficiency, partly due to a decrease in the bulk mobility of the constituent materials upon annealing but also (and significantly) due to the increased interface roughness. We present results of Monte Carlo simulations that demonstrate that increased interface roughness leads to lower charge separation efficiency, and are able to reproduce the experimental current-voltage curves taking both increased interfacial roughness and decreased carrier mobility into account. Our results show that organic photovoltaic performance can be sensitive to interfacial order, and heterojunction sharpness should be considered a requirement for high performance devices. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Synthesis and electrochemical properties of novel, donor–acceptor pyrrole derivatives with 1,8-naphthalimide units and their polymers

    International Nuclear Information System (INIS)

    Ledwon, Przemyslaw; Brzeczek, Alina; Pluczyk, Sandra; Jarosz, Tomasz; Kuznik, Wojciech; Walczak, Krzysztof; Lapkowski, Mieczyslaw

    2014-01-01

    A new class of bipolar monomers with pyrrole or thiophene–pyrrole–thiophene as electron donor and 1,8-naphthalimide as electron acceptor unit is reported. Donor–acceptor conjugated polymers were generated electrochemically. The synthesis of monomers, optical, electrochemical and spectroelectrochemical properties supported by theoretical calculations are presented. 1,8-naphthalimide units were attached directly to pyrrole in compounds 1a and 2a or by different bridges in the case of 1b and 2b. Intra-molecular donor–acceptor interactions of the monomers and its polymers were investigated using cyclic voltammetry, in-situ UV–Vis-NIR, electron spin resonance (ESR) spectroelectrochemistry and fluorescence spectroscopy. Studied compounds present large discrepancy (up to 1.31 eV for 2a) between energy gap values determined through electrochemical and optical measurements. The Time-dependent density functional theory (TDDFT) calculations help to explain this discrepancy. This is caused by weak HOMO to LUMO transition, 2000 times weaker than HOMO −2 to LUMO or HOMO to LUMO +1 transition. Altering the structure of monomers yields different stability and properties of obtained polymers. The p- and n-doping processes are separated. Anions are localized mainly on 1,8-naphthalimide units. Cations are localized mainly on pyrrole or thiophene–pyrrole–thiophene moiety and their polymer chains. Attachment of the additional thiophene units decreases the oxidation potential of the monomer and reduces the influence of the steric hindrance between 1,8-naphthalimide moiety and polymer/oligomers chain. This new class of model compounds is promising for use as a material with enhanced charge separation for wide range of optoelectronic, electrochromic and photovoltaic applications

  11. Study of heat transfer conditions at the wall of an ingot heated by electron gun; Etude des conditions d'echange thermique a la paroi d'un lingot chauffe par un canon a electrons

    Energy Technology Data Exchange (ETDEWEB)

    Saturnin, A.; Triffart, B. [CEA Vallee du Rhone, Dept. de Technologie de l' Enrichissement (DCC/DTE/STS), 26 - Pierrelatte (France)

    2000-07-01

    A metal confined in a crucible is heated by an electron beam to produce metallic vapor. Only a small proportion of the electron beam energy is used to vaporize the metal. Another portion is lost because of backscattered electrons and thermal radiation of the ingot. The remaining energy is transmitted by convection and conduction to the water cooled crucible. The knowledge of this energy, and particularly its spatial distribution, is important. The magnitude of the heat flux can be analyzed to ensure component integrity. The spatial flux distribution provides information about the coolant system homogeneity, which is related to the position of the ingot in the crucible and the electron beam alignment. These data are useful for controlling operating conditions. In the present method, the heat flux at the crucible wall is identified by conventional measurements (thermocouples, flowmeter) and an inverse method. This approach makes it unnecessary to model complex mechanisms in the liquid metal pool, limiting the study to the heat transfers inside the crucible. Calculation of the flux at a given point of the crucible wall requires three essential data: coolant system temperature Te, crucible temperature Tmes at the measurement point Pmes and temperature sensitivity at this point to heat flux variations at the wall. This characteristic is also called the sensitivity coefficient. It is obtained by modeling heat transfers in the crucible (convective with coolant system, conductive in the crucible) with the boundary conditions Te = 0 K and {phi} 1 Wm{sup -2}. This approach is a simple application of the function specification method, which is a reference method in inverse problems. The problem is assumed to be linear and stationary because of the high thermal crucible conductivity and the measurement locations (close to the wall). If the sensitivity coefficient is known, the heat flux can be calculated by equation (1). Figure 2 shows an example of variations in Tmes and Te

  12. Progress in ZnO Acceptor Doping: What Is the Best Strategy?

    Directory of Open Access Journals (Sweden)

    Judith G. Reynolds

    2014-01-01

    Full Text Available This paper reviews the recent progress in acceptor doping of ZnO that has been achieved with a focus toward the optimum strategy. There are three main approaches for generating p-type ZnO: substitutional group IA elements on a zinc site, codoping of donors and acceptors, and substitution of group VA elements on an oxygen site. The relevant issues are whether there is sufficient incorporation of the appropriate dopant impurity species, does it reside on the appropriate lattice site, and lastly whether the acceptor ionization energy is sufficiently small to enable significant p-type conduction at room temperature. The potential of nitrogen doping and formation of the appropriate acceptor complexes is highlighted although theoretical calculations predict that nitrogen on an oxygen site is a deep acceptor. We show that an understanding of the growth and annealing steps to achieve the relevant acceptor defect complexes is crucial to meet requirements.

  13. Photo-switchable Donor-Acceptor (D-A) Dyad Interfacial Self-Assembled Monolayers for Organic Photovoltaic Cells

    Science.gov (United States)

    2015-11-05

    Dye-Sensitized Solar Cells," Dyes and Pigments , 107, 9-14, 2014 (DOI: 10.1016/j.dyepig.2014.03.010). Here we report the synthesis and...electron acceptor and anchoring unit for Dye-Sensitized Solar Cells,\\" Dyes and Pigments , 107, 9-14, 2014 (DOI: 10.1016/j.dyepig.2014.03.010). 4. Danny...linked by vinyl-fluorene or vinyl-thiophene spacers for dye-sensitized solar cells,” Dyes and Pigments , 112, 127-137, 2014 (DOI: 10.1016/j.dyepig

  14. Taming hot CF3 radicals: incrementally tuned families of polyarene acceptors for air-stable molecular optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Kuvychko, Igor V.; Castro, Karlee P.; Deng, Shihu; Wang, Xue B.; Strauss, Steven H.; Boltalina, Olga V.

    2013-04-26

    Breakthroughs in molecular optoelectronics await the availability of new families of air-stable polyaromatic hydrocarbon (PAH) acceptors with incrementally- and predictably-tunable electron affinities and structures capable of inducing desirable solid-state morphologies in hybrid materials. Although the addition of electron withdrawing groups to PAHs has been studied for decades, producing new compounds from time to time, a generic one-step synthetic methodology applicable to potentially all PAH substrates has been, until now, an impossible dream. We herein report that at least seventeen common PAHs and polyheterocyclics can be trifluoromethylated by a new procedure to yield families of PAH(CF3)n acceptors with (i) n = 4-8, (ii) multiple isomers for particular n values, (iii) gas-phase experimental electron affinities as high as 3.32 eV and shifted from the respective PAH precursor as a linear function of n, and (iv) various solid-state morphologies, including the ability to form alternating π stacked hybrid crystals with aromatic donors.

  15. Binding characteristics of homogeneous molecularly imprinted polymers for acyclovir using an (acceptor-donor-donor)-(donor-acceptor-acceptor) hydrogen-bond strategy, and analytical applications for serum samples.

    Science.gov (United States)

    Wu, Suqin; Tan, Lei; Wang, Ganquan; Peng, Guiming; Kang, Chengcheng; Tang, Youwen

    2013-04-12

    This paper demonstrates a novel approach to assembling homogeneous molecularly imprinted polymers (MIPs) based on mimicking multiple hydrogen bonds between nucleotide bases by preparing acyclovir (ACV) as a template and using coatings grafted on silica supports. (1)H NMR studies confirmed the AAD-DDA (A for acceptor, D for donor) hydrogen-bond array between template and functional monomer, while the resultant monodisperse molecularly imprinted microspheres (MIMs) were evaluated using a binding experiment, high performance liquid chromatography (HPLC), and solid phase extraction. The Langmuir isothermal model and the Langmuir-Freundlich isothermal model suggest that ACV-MIMs have more homogeneous binding sites than MIPs prepared through normal imprinting. In contrast to previous MIP-HPLC columns, there were no apparent tailings for the ACV peaks, and ACV-MIMs had excellent specific binding properties with a Ka peak of 3.44 × 10(5)M(-1). A complete baseline separation is obtained for ACV and structurally similar compounds. This work also successfully used MIMs as a specific sorbent for capturing ACV from serum samples. The detection limit and mean recovery of ACV was 1.8 ng/mL(-1) and 95.6%, respectively, for molecularly imprinted solid phase extraction coupled with HPLC. To our knowledge, this was the first example of MIPs using AAD-DDA hydrogen bonds. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Tuning the Optoelectronic Properties of Vinylene-Linked Donor−Acceptor Copolymers for Organic Photovoltaics

    KAUST Repository

    Ko, Sangwon

    2010-08-24

    Five new donor-acceptor copolymers containing the electron acceptor benzothiadiazole (BTZ) linked to the electron donors fluorene (FL) or cyclopentadithiophene (CPDT) via vinylene units were synthesized to study polymer structure-property relationships in organic photovoltaic devices. Both alternating (P) and random copolymers (P1-P4) were prepared via Suzuki and Stille polycondensations, respectively. The cyclopentadithiophene copolymers (P2 and P4) have smaller electrochemical band gaps (1.79 and 1.64 eV) compared to the fluorene-containing copolymers (2.08 and 1.95 eV for P1 and P3). However, the presence of CPDT raises the electrochemical HOMO energy levels (-4.83 and-4.91 eV for P2 and P4) compared to the FL copolymers (-5.06 and-5.15 eV for P1 and P3) leading to small open circuit voltages (Voc) in solar cells. The primary solution and thin-film UV-vis absorption peaks of P3 and P4, which do not contain alkylated thiophenes appended to the BTZ unit, are at lower energy and have larger absorption coefficients than their P1 and P2 counterparts. Detailed theoretical analyses of the geometric structure, electronic structure, and excited-state vertical transitions using density functional theory provide direct insight into the interplay between the structural modifications and resulting electronic and optical changes. A high molecular weight (Mn = 25 kg/mol) polymer with a large degree of polymerization (DPn = 21) was easily achieved for the random copolymer P1, leading to thin films with both a larger absorption coefficient and a larger hole mobility compared to the analogous alternating polymer P (Mn = 22 kg/mol, DPn = 18). An improved short circuit current and a power conversion efficiency up to 1.42% (Jsc = 5.82 mA/cm2, Voc = 0.765 V, and FF = 0.32) were achieved in bulk heterojunction solar cells based on P1. © 2010 American Chemical Society.

  17. Cu/ZnO nanocatalysts in response to environmental conditions: surface morphology, electronic structure, redox state and CO2 activation.

    Science.gov (United States)

    Martínez-Suárez, Luis; Frenzel, Johannes; Marx, Dominik

    2014-12-21

    Methanol synthesis is one of the landmarks of heterogeneous catalysis due to the great industrial significance of methanol as a clean liquid fuel and as a raw material for industry. Understanding in atomistic detail the properties of the underlying metal/oxide catalyst materials as a function of temperature and composition of the reactive gas phase is of utmost importance in order to eventually improve the production process. By performing extensive density functional theory based slab calculations in combination with a thermodynamic formalism we establish an atomistic understanding of gas phase-induced changes of surface morphology, redox properties and reactivity of ZnO supported Cu nanocatalysts. Extending our recent insights [Phys. Rev. Lett., 2013, 110, 086108], we explore surface stabilization mechanisms and site-dependent redox states of both catalyst components as well as the pronounced electronic charge transfer processes across the metal-support interface. Moreover, ab initio molecular dynamics simulations unveil the vital role played by dynamical shape fluctuations of the deposited Cu8 cluster. The pronounced structural flexibility of the metal nanoparticle is found to enhance CO2 activation over Cu8 at the elevated temperature conditions of the industrial methanol synthesis process, in addition to activation of CO2via electronic charge transfer from the ZnO support.

  18. Measurements of the performance of a beam condition monitor prototype in a 5 GeV electron beam

    Science.gov (United States)

    Hempel, M.; Afanaciev, K.; Burtowy, P.; Dabrowski, A.; Henschel, H.; Idzik, M.; Karacheban, O.; Lange, W.; Leonard, J.; Levy, I.; Lohmann, W.; Pollak, B.; Przyborowski, D.; Ryjov, V.; Schuwalow, S.; Stickland, D.; Walsh, R.; Zagozdzinska, A.

    2016-08-01

    The Fast Beam Conditions Monitor, BCM1F, in the Compact Muon Solenoid, CMS, experiment was operated since 2008 and delivered invaluable information on the machine induced background in the inner part of the CMS detector supporting a safe operation of the inner tracker and high quality data. Due to the shortening of the time between two bunch crossings from 50 ns to 25 ns and higher expected luminosity at the Large Hadron Collider, LHC, in 2015, BCM1F needed an upgrade to higher bandwidth. In addition, BCM1F is used as an on-line luminometer operated independently of CMS. To match these requirements, the number of single crystal diamond sensors was enhanced from 8 to 24. Each sensor is subdivided into two pads, leading to 48 readout channels. Dedicated fast front-end ASICs were developed in 130 nm technology, and the back-end electronics is completely upgraded. An assembled prototype BCM1F detector comprising sensors, a fast front-end ASIC and optical analog readout was studied in a 5 GeV electron beam at the DESY-II accelerator. Results on the performance are given.

  19. Quality control of radiotherapy centres in the Slovak Republic: a dosimetry intercomparison of photon and electron beams under reference conditions

    International Nuclear Information System (INIS)

    Gomola, I.; Kralik, G.; Laginova, V.; Van Dam, J.

    2001-01-01

    The aim of this paper is a dosimetry intercomparison of photon and electron beams under reference conditions as well as quality control of radiotherapy centres in the Slovak Republic. The results obtained in the first check shows that only about 60% of beams are within the acceptance limit. The reasons of discrepancies were traced, in some cases by an on site visit of experts from the NRC, and unacceptable deviations were corrected. The results clearly demonstrate the usefulness of the external dosimetry checks performed with the mailed thermoluminescent dosimeters. Standard deviation of the distribution of the results decreased from SD=4.3% to SD=I.8% for checked photon beams and from SD=8.6% to SD=2.4% for electron beams, respectively, at the end of the project. The dosimetry audits which are performed in regular intervals significantly decreasing a possibility of mistreatment (under-dosage or over-dosage ) of patients due to wrong calibration of radiation therapy beams. In order to keep the reached level of dosimetry precision, it is necessary to establish the external audit in radiotherapy at the national level based on postal TLD dosimetry by transferring the know-how from the international program on quality assurance in radiotherapy dosimetry with the assistance of the IAEA. (authors)

  20. Synthesis and properties of a decacyclene monoimide and a naphthalimide derivative as a three-dimensional acceptor-donor-acceptor system.

    Science.gov (United States)

    Kawase, Takeshi; Yamamoto, Yuma; Yoshida, Miu; Morii, Takuya; Nishida, Jun-Ichi; Kitamura, Chitoshi

    2018-02-06

    A method, which employs Diels-Alder (DA) cycloadditions of diacenaphtheno[1,2-b;1',2'-d]thiophenes (DAT) with N-alkylacenaphthylene-5,6-dicarboximides (AI), was developed to synthesize decacyclene monoimides (DCMI). The reactions generate the corresponding 1:2 adducts (BAIAs) as major products together with 1:1 adducts (DCMIs). The molecular structure of BAIAb (N-octyl derivative) was unambiguously assigned as the bis-adduct having an endo,endo spatial disposition of the two acenaphthylene-5,6-dicarboximide moieties by using X-ray crystallographic analysis. Relative to that of decacyclene triimide (DCTIa, N-2-ethylhexyl derivative), the analogous N-2-ethylhexyl-substituted mono-adduct DCMIa exhibits a bathochromic shift in its absorption spectrum despite possessing a less delocalized π-electron system. DCMIa does not fluoresce in various organic solvents, while DCTIa emits yellow fluorescence in CH2Cl2 with a low quantum yield (SN). Moreover, DCMIa in CDCl3 displays concentration-dependent 1H-NMR behavior, suggesting that it self-aggregates with an (association constant (Ka) of 193 ± 50 M-1 at 20 °C. Despite the presence of four bulky t-butyl groups in DCMIa, its Ka value for aggregate formation is comparable to that of DCTIa (495 ± 42 M-1), which does not contain t-butyl substituents. Spectroscopic studies with the bis-adduct BAIAa (N-2-ethylhexyl derivative) show that it displays remarkable solvatofluorochromism corresponding to an emission maximum shift (ΔλEM) of 100 nm. The results of density functional theory (DFT) calculations on BAIAc (N-methyl derivative) demonstrate that a considerable spatial separation exists between the HOMO and LUMO coefficient distributions, indicating that the ground-to-excited state transition of the novel three-dimensional acceptor-donor-acceptor system BAIAa should have intramolecular charge transfer (ICT) character. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Anaerobic degradation of a mixture of MtBE, EtBE, TBA, and benzene under different redox conditions.

    Science.gov (United States)

    van der Waals, Marcelle J; Pijls, Charles; Sinke, Anja J C; Langenhoff, Alette A M; Smidt, Hauke; Gerritse, Jan

    2018-04-01

    The increasing use of biobased fuels and fuel additives can potentially change the typical fuel-related contamination in soil and groundwater. Anaerobic biotransformation of the biofuel additive ethyl tert-butyl ether (EtBE), as well as of methyl tert-butyl ether (MtBE), benzene, and tert-butyl alcohol (TBA, a possible oxygenate metabolite), was studied at an industrially contaminated site and in the laboratory. Analysis of groundwater samples indicated that in the field MtBE was degraded, yielding TBA as major product. In batch microcosms, MtBE was degraded under different conditions: unamended control, with medium without added electron acceptors, or with ferrihydrite or sulfate (with or without medium) as electron acceptor, respectively. Degradation of EtBE was not observed under any of these conditions tested. TBA was partially depleted in parallel with MtBE. Results of microcosm experiments with MtBE substrate analogues, i.e., syringate, vanillate, or ferulate, were in line with the hypothesis that the observed TBA degradation is a cometabolic process. Microcosms with ferulate, syringate, isopropanol, or diethyl ether showed EtBE depletion up to 86.5% of the initial concentration after 83 days. Benzene was degraded in the unamended controls, with medium without added electron acceptors and with ferrihydrite, sulfate, or chlorate as electron acceptor, respectively. In the presence of nitrate, benzene was only degraded after addition of an anaerobic benzene-degrading community. Nitrate and chlorate hindered MtBE, EtBE, and TBA degradation.

  2. Charge transfer complex of some nervous and brain drugs - Part 1: Synthesis, spectroscopic, analytical and biological studies on the reaction between haloperidol antipsychotic drugs with π-acceptors

    Science.gov (United States)

    El-Habeeb, Abeer A.; Al-Saif, Foziah A.; Refat, Moamen S.

    2013-02-01

    Donor-acceptor interactions between the electron donor haloperidol (HPL) and π-acceptors like 7,7,8,8-tetracyanoquinodimethane (TCNQ) and picric acid (PA) have been studied spectrophotometrically in CH3OH solvent. The donor-acceptor (charge transfer complexes) were discussed in terms of formation constant (KCT), molar extinction coefficient (ɛCT), standard free energy (ΔGo), oscillator strength (ƒ), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID). The stoichiometry of these complexes was found to be 1:1 M ratio and having the formulas [(HPL)(TCNQ)] and [(HPL)(PA)], respectively. The charge transfer interaction was successfully applied to determine of HPL drug using mentioned common π-acceptors also, the results obtained herein are satisfactory for estimation of HPL compound in the pharmaceutical form. The formed solid charge-transfer complexes were also isolated and characterized using elemental analysis, conductivity, (infrared, Raman, and 1H NMR) spectra and X-ray powder diffraction (XRD). The experimental data of elemental analyses are in agreement with calculated data. The infrared spectra of both HPL complexes are confirming the participation of sbnd OH of 4-hydroxy-1-piperidyl moiety in the donor-acceptor chelation. The morphological surface of the resulted charge transfer complexes were investigated using scanning electron microscopy (SEM). The thermogravimetric analysis (TG/DTG) and differential scanning calorimetry (DSC) techniques were performed to give knowledge about the thermal stability behavior of the synthesized charge transfer complexes. Thermodynamic parameters were computed from the thermal decomposition data. These complexes were also tested for their antimicrobial activity against six different microorganisms, and the results were compared with the parent drug.

  3. Donors in Semiconductors - are they Understood in Electronic Era?

    International Nuclear Information System (INIS)

    Dmochowski, Janusz E

    2007-01-01

    The physics of semiconductors and contemporary electronics cannot be understood without impurities. The hydrogen-like shallow donor (and acceptor) state of electron (hole) bound by Coulomb electrostatic force of excess charge of impurity is used to control conductivity of semiconductors and construct semiconductor diodes, transistors and numerous types of semiconductor electronic and optoelectronic devices, including lasers. Recently, surprisingly, the physics of impurity donors appeared to be much reacher. Experimental evidence has been provided for universal existence of other types of electronic states of the same donor impurity: i) mysterious, deep, DX-type state resulting in metastability - slow hysteresis phenomena - understood as two-electron, acceptor-like state of donor impurity, formed upon large lattice distortion or rearrangement around impurity and accompanying capture of second electron, resulting in negative electron correlation energy U; ii) deep, localized, fully symmetric, A1, one-electron donor state of substitutional impurity. The latter state can be formed from the 'ordinary' shallow hydrogen-like state in the process of strong localization of electron by short range, local potential of impurity core, preserving full (A 1 ) symmetry of the substitutional impurity in the host lattice. The 'anticrossing' of the two A 1 (shallow hydrogenic and deep localized) energy levels upon transformation is observed. All types of electronic states of impurity can be universally observed for the same donor impurity and mutual transformation between different states occur upon changing experimental conditions. The knowledge about existence and properties of these n ew , molecular type, donor states in semiconductors seems still await general recognition and positive application in contemporary material and device science and engineering

  4. New lab scale approaches for quantification of redox conditions

    Science.gov (United States)

    Fernandez, P. M.; Dathe, A.; Nadeem, S.; Bakken, L. R.; Bloem, E.; French, H. K.; Binley, A. M.

    2013-12-01

    Degradation of organic chemicals in the unsaturated zone is a process highly relevant for developing remediation techniques for protecting groundwater. Degradation causes changes in chemical composition of the water phase and gas releases. These changes can potentially be mapped with electrical resistivity measurements in the bulk soil and gas measurements at the soil surface. The redox potential combined with the local geological conditions determines the composition of available electron acceptors as well as microbial degradation pathways and how the soil system is affected in the long term. After oxygen and nitrate are depleted, manganese and iron should be reduced. However, in experiments conducted in the unsaturated zone at Gardermoen airport, Norway, it was found that for the degradation of the de-icing agent propylene glycol (PG), manganese and iron were preferred over nitrate as electron acceptor. A key hypothesis for the work presented is that for a designated soil, the redox potential affects gas releases and soil solution composition profoundly. As the redox potential decreases, the reactants of the degradation change and therefore the composition of the soil-water system changes. These changes can be quantified dynamically by gas measurements and changes in electrical conductivity of the pore water and electrical resistivity of the bulk soil. Batch experiments were conducted to examine whether nitrate is a preferred electron acceptor over iron and manganese oxides as described in classical redox reaction theory. Gas releases during PG and glutamate degradation were measured in a sandy pristine soil with and without nitrate under anaerobic condition during two weeks of incubation. Chemical reactions were quantified with the modelling tool ORCHESTRA. We are currently investigating whether dynamical measurements of electrical conductivity and bulk resistivity are suited to trace which electron acceptors (nitrate, manganese or iron) are being reduced. First

  5. Efficiency and limitation of periodic sample multiplication to reduce computational load in Monte Carlo simulations of electron swarms in gas under attachment-dominated conditions

    Science.gov (United States)

    Sugawara, Hirotake

    2018-03-01

    In Monte Carlo simulations of electron swarms, sample electrons were copied periodically so that a sufficient number of samples are obtained in equilibrium after relaxation even under a severe attachment-dominated condition where most electrons vanish during the relaxation. The final sampling results were equivalent to those sampled by a conventional method, and the computational time conventionally wasted for the tracking of vanishing electrons was reduced drastically. The time saved can be utilized for tracking more samples to reduce statistical fluctuation. The efficiency of this technique and its limitation are discussed quantitatively together with details on its implementation.

  6. Controlling Blend Morphology for Ultra-High Current Density in Non-Fullerene Acceptor Based Organic Solar Cells

    KAUST Repository

    Song, Xin

    2018-01-23

    Due to the high absorption coefficient and modulated band gap of non-fullerene small molecule acceptors (NFAs), photons can be utilized more efficiently in near-infrared (NIR) range. In this report, we highlight a system with a well-known polymer donor (PTB7-Th) blended with a narrow bandgap non-fullerene acceptor (IEICO-4F) as active layer and 1-chloronaphthalene (CN) as the solvent additive. The optimization of the photoactive layer nanomorphology yields short-circuit current density value (Jsc) of 27.3 mA/cm2, one of the highest value in OSCs reported to date, which competes with other types of solution processed solar cells such as perovskite or quantum dot devices. Along with decent open-circuit voltage (0.71V) and fill factor values (66%), a power conversion efficiency of 12.8% is achieved for the champion devices. Grazing incidence wide-angle X-ray scattering (GIWAXS) patterns and resonant soft X-ray scattering (R-SoXS) elucidate that the origin of this high photocurrent is mainly due to increased π-π coherence length of the acceptor, the domain spacing as well as the mean-square composition variation of the blend. Optoelectronic measurements confirm a balanced hole and electron mobility and reduced trap-assisted recombination for the best devices. These findings unveil the relevant solvent processing-nanostructure-electronic properties correlation in low band gap non-fullerene based solar cells, which provide a helpful guide for maximizing photocurrent that can pave the way for high efficiency organic solar cells.

  7. Creating Graphitic Carbon Nitride Based Donor-π-Acceptor-π-Donor Structured Catalysts for Highly Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Li, Kui; Zhang, Wei-De

    2018-03-01

    Conjugated polymers with tailored donor-acceptor units have recently attracted considerable attention in organic photovoltaic devices due to the controlled optical bandgap and retained favorable separation of charge carriers. Inspired by these advantages, an effective strategy is presented to solve the main obstructions of graphitic carbon nitride (g-C 3 N 4 ) photocatalyst for solar energy conversion, that is, inefficient visible light response and insufficient separation of photogenerated electrons and holes. Donor-π-acceptor-π-donor polymers are prepared by incorporating 4,4'-(benzoc 1,2,5 thiadiazole-4,7-diyl) dianiline (BD) into the g-C 3 N 4 framework (UCN-BD). Benefiting from the visible light band tail caused by the extended π conjugation, UCN-BD possesses expanded visible light absorption range. More importantly, the BD monomer also acts as an electron acceptor, which endows UCN-BD with a high degree of intramolecular charge transfer. With this unique molecular structure, the optimized UCN-BD sample exhibits a superior performance for photocatalytic hydrogen evolution upon visible light illumination (3428 µmol h -1 g -1 ), which is nearly six times of that of the pristine g-C 3 N 4 . In addition, the photocatalytic property remains stable for six cycles in 3 d. This work provides an insight into the synthesis of g-C 3 N 4 -based D-π-A-π-D systems with highly visible light response and long lifetime of intramolecular charge carriers for solar fuel production. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 stimulated with external electron donors under alkaline conditions

    International Nuclear Information System (INIS)

    Xu Lin; Luo Mingfang; Li Wangliang; Wei Xuetuan; Xie Keng; Liu Lijun; Jiang Chengying; Liu Huizhou

    2011-01-01

    Research highlights: → Growing cells have high Cr (VI) resistant and reducing ability aerobically. → Resting cells show strong anaerobic-reduction potential. → Acetate can highly stimulate both aerobic and anaerobic reduction process. - Abstract: A novel Cr (VI) resistant bacterial strain LSSE-09, identified as Pannonibacter phragmitetus, was isolated from industrial sludge. It has strong aerobic and anaerobic Cr (VI)-reduction potential under alkaline conditions. At 37 o C and pH 9.0, growing cells of strain LSSE-09 could completely reduce 100 and 1000 mg L -1 Cr (VI)-Cr (III) within 9 and 24 h, respectively under aerobic condition. Resting cells showed higher anaerobic reduction potential with the rate of 1.46 mg g -1 (dryweight) min -1 , comparing with their aerobic reduction rate, 0.21 mg g -1 min -1 . External electron donors, such as lactate, acetate, formate, pyruvate, citrate and glucose could highly increase the reduction rate, especially for aerobic reduction. The presence of 3000 mg L -1 acetate enhanced anaerobic and aerobic Cr (VI)-reduction rates up to 9.47 mg g -1 min -1 and 4.42 mg g -1 min -1 , respectively, which were 5 and 20 times faster than those without it. Strain LSSE-09 retained high activities over six batch cycles and NO 3 - and SO 4 2- had slightly negative effects on Cr (VI)-reduction rates. The results suggest that strain LSSE-09 has potential application for Cr (VI) detoxification in alkaline wastewater.

  9. The CMS fast beams condition monitor back-end electronics based on MicroTCA technology: status and development

    Science.gov (United States)

    Zagozdzinska, Agnieszka A.; Dabrowski, Anne E.; Pozniak, Krzysztof T.

    2015-09-01

    The Fast Beams Condition Monitor (BCM1F), upgraded for LHC Run II, is used to measure the online luminosity and machine induced background for the CMS experiment. The detector consists of 24 single-crystal CVD diamond sensors that are read out with a custom fast front-end chip fabricated in 130 nm CMOS technology. Since the signals from the sensors are used for real time monitoring of the LHC conditions they are processed by dedicated back-end electronics to measure separately rates corresponding to LHC collision products, machine induced background and residual activation exploiting different arrival times. The system is built in MicroTCA technology and uses high speed analog-to-digital converters. In operational modes of high rates, consecutive events, spaced in time by less than 12.5 ns, may cause partially overlapping events. Hence, novel signal processing techniques are deployed to resolve overlapping peaks. The high accuracy qualification of the signals is crucial to determine the luminosity and the machine induced background rates for the CMS experiment and the LHC.

  10. Architecture of the upgraded BCM1F Backend Electronics for Beam Conditions and Luminosity measurement - hardware and firmware

    CERN Document Server

    Zagozdzinska, Agnieszka Anna; Przyborowski, D.; Leonard, J.L.; Pozniak, K.T.; Miraglia, M.; Walsh, R.; Lange, W.; Lohmann, W.; Ryjov, V.

    2015-01-01

    The Beam Radiation Instrumentation and Luminosity Project of the CMS experiment, consists of several beam monitoring systems. One system, the upgraded Fast Beams Condition Monitor, is based on 24 single crystal CVD diamonds with a double-pad sensor metallization and a custom designed readout. Signals for real time monitoring are transmitted to the counting room, where they are received and processed by new back-end electronics designed to extract information on LHC collision, beam induced background and activation products. Data in the form of histograms is transmitted to the DAQ. The system architecture and the signal processing algorithms will be presented.SummaryThe Fast Beam Conditions Monitor (BCM1F) detector is a part of the CMS Beam Radiation Instrumentation and Luminosity Project (BRIL). The increased performance expected of the LHC with energy of up to 14 TeV, higher luminosity and 25 ns bunch spacing is a challenge for the detector systems and increase the importance of real-time beam monitoring at ...

  11. Dependence of the Mg-related acceptor ionization energy with the acceptor concentration in p-type GaN layers grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Brochen, Stéphane; Brault, Julien; Chenot, Sébastien; Dussaigne, Amélie; Leroux, Mathieu; Damilano, Benjamin

    2013-01-01

    Hall effect and capacitance-voltage C(V) measurements were performed on p-type GaN:Mg layers grown on GaN templates by molecular beam epitaxy with a high range of Mg-doping concentrations. The free hole density and the effective dopant concentration N A −N D as a function of magnesium incorporation measured by secondary ion mass spectroscopy clearly reveal both a magnesium doping efficiency up to 90% and a strong dependence of the acceptor ionization energy Ea with the acceptor concentration N A . These experimental observations highlight an isolated acceptor binding energy of 245±25 meV compatible, at high acceptor concentration, with the achievement of p-type GaN:Mg layers with a hole concentration at room temperature close to 10 19 cm −3

  12. Use of electronic health records and administrative data for public health surveillance of eye health and vision-related conditions in the United States.

    Science.gov (United States)

    Elliott, Amanda F; Davidson, Arthur; Lum, Flora; Chiang, Michael F; Saaddine, Jinan B; Zhang, Xinzhi; Crews, John E; Chou, Chiu-Fang

    2012-12-01

    To discuss the current trend toward greater use of electronic health records and how these records could enhance public health surveillance of eye health and vision-related conditions. Perspective, comparing systems. We describe 3 currently available sources of electronic health data (Kaiser Permanente, the Veterans Health Administration, and the Centers for Medicare & Medicaid Services) and how these sources can contribute to a comprehensive vision and eye health surveillance system. Each of the 3 sources of electronic health data can contribute meaningfully to a comprehensive vision and eye health surveillance system, but none currently provide all the information required. The use of electronic health records for vision and eye health surveillance has both advantages and disadvantages. Electronic health records may provide additional information needed to create a comprehensive vision and eye health surveillance system. Recommendations for incorporating electronic health records into such a system are presented. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Efficient Naphthalenediimide-Based Hole Semiconducting Polymer with Vinylene Linkers between Donor and Acceptor Units

    KAUST Repository

    Zhang, Lei

    2016-11-04

    We demonstrate a new method to reverse the polarity and charge transport behavior of naphthalenediimide (NDI)-based copolymers by inserting a vinylene linker between the donor and acceptor units. The vinylene linkers minimize the intrinsic steric congestion between the NDI and thiophene moieties to prompt backbone planarity. The polymers with vinylene linkers exhibit electron n-channel transport characteristics under vacuum, similar to the benchmark polymer, P(NDI2OD-T2). To our surprise, when the polymers are measured in air, the dominant carrier type switches from n- to p-type and yield hole mobilities up to 0.45 cm(2) s(-1) with hole to electron mobility ratio of three (mu(h)/mu(e), similar to 3), which indicates that the hole density in the active layer can be significantly increased by exposure to air. This increase is consistent with the intrinsic more delocalized nature of the highest occupied molecular orbital of the charged vinylene polymer, as estimated by density functional theory (DFT) calculations, which facilitates hole transport within the polymer chains. This is the first demonstration of an efficient NDI-based hole semiconducting polymer, which will enable new developments in all-polymer solar cells, complementary circuits, and dopable polymers for use in thermoelectrics.

  14. Ultrasmall magnetic field-effect and sign reversal in transistors based on donor/acceptor systems

    Directory of Open Access Journals (Sweden)

    Thomas Reichert

    2017-05-01

    Full Text Available We present magnetoresistive organic field-effect transistors featuring ultrasmall magnetic field-effects as well as a sign reversal. The employed material systems are coevaporated thin films with different compositions consisting of the electron donor 2,2',7,7'-tetrakis-(N,N-di-p-methylphenylamino-9,9'-spirobifluorene (Spiro-TTB and the electron acceptor 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile (HAT-CN. Intermolecular charge transfer between Spiro-TTB and HAT-CN results in a high intrinsic charge carrier density in the coevaporated films. This enhances the probability of bipolaron formation, which is the process responsible for magnetoresistance effects in our system. Thereby even ultrasmall magnetic fields as low as 0.7 mT can influence the resistance of the charge transport channel. Moreover, the magnetoresistance is drastically influenced by the drain voltage, resulting in a sign reversal. An average B0 value of ≈2.1 mT is obtained for all mixing compositions, indicating that only one specific quasiparticle is responsible for the magnetoresistance effects. All magnetoresistance effects can be thoroughly clarified within the framework of the bipolaron model.

  15. Descoloração redutiva de corantes azo e o efeito de mediadores redox na presença do aceptor de elétrons sulfato Reductive decolourisation of azo dyes and the effect of redox mediators in the presence of the electron acceptor sulfate

    Directory of Open Access Journals (Sweden)

    Mayara Carantino Costa

    2010-01-01

    Full Text Available We investigated the impact of sulphate and the redox mediator Anthraquinone-2,6-disulfonate (AQDS on the decolorization of the azo dyes Congo Red (CR and Reactive Black 5 (RB5. In anaerobic reactors free of extra sulphate dosage, the color removal efficiency decreased drastically when the external electron donor ethanol was removed. In presence of an extra dosage of sulphate, CR decolourisations were 47.8% (free of AQDS and 96.5% (supplemented with AQDS. The decolourisations achieved in both reactors with RB5 were lower than the ones found with CR. Finally, the biogenic sulphide contribution on azo dye reduction was negligiable.

  16. Charge trapping in polymer dielectrics and potentials at organic donor-acceptor junctions-the role of interface and bulk contributions

    Science.gov (United States)

    Alley, Olivia

    Organic electronics have attracted increasing interest during the past decade due to their potential applications in transparent, large-area, printable, and stretchable devices. Solution based material deposition considerably reduces processing costs, and allows the use of non-standard substrates in device design. Many organic electronic device parameters are controlled by interfacial as well as bulk properties. Organic donor-acceptor junctions are relevant to organic photovoltaics (OPVs) as well as organic light emitting diodes (OLEDs). In an OPV, interfacial potentials between the hole transporting (donor) organic semiconductor (OSC) and electron transporting OSC (acceptor) lead to separation and recombination of electrons and holes. The mechanisms behind interfacial potential formation in organic donor-acceptor junctions are not fully understood and are an active area of study. In this thesis, the interfacial potential was measured, and interface and bulk contributions were separated by fabricating lateral organic donor-acceptor junctions both with and without a gap between the donor and acceptor materials. Contact between the donor and acceptor materials increases the interfacial potential beyond that calculated from bulk values. This can be explained through differences in electron affinity of the donor and acceptor, and also by differences in the delocalization of molecular orbitals (MOs) of the two OSC films. Greater delocalization of MOs allows for electron donation to adjacent molecules, a surprising result in organic electronics. In addition, the effect of the substrate on the potential was examined. The field is persistently negative on the acceptor side when the junction is made on a SiO2 substrate. When Al2Oi3, a substrate with higher dielectric constant, is used, the field decreases in one case, and reverses in the other. For organic field effect transistors (OFETs), the instability of switching voltages is an interface-dominated issue which causes

  17. Encapsulation of ropivacaine in a combined (donor-acceptor, ionic-gradient liposomal system promotes extended anesthesia time.

    Directory of Open Access Journals (Sweden)

    Camila Morais Gonçalves da Silva

    Full Text Available Ropivacaine is a local anesthetic with similar potency but lower systemic toxicity than bupivacaine, the most commonly used spinal anesthetic. The present study concerns the development of a combined drug delivery system for ropivacaine, comprised of two types of liposomes: donor multivesicular vesicles containing 250 mM (NH42SO4 plus the anesthetic, and acceptor large unilamellar vesicles with internal pH of 5.5. Both kinds of liposomes were composed of hydrogenated soy-phosphatidylcholine:cholesterol (2:1 mol% and were prepared at pH 7.4. Dynamic light scattering, transmission electron microscopy and electron paramagnetic resonance techniques were used to characterize the average particle size, polydispersity, zeta potential, morphology and fluidity of the liposomes. In vitro dialysis experiments showed that the combined liposomal system provided significantly longer (72 h release of ropivacaine, compared to conventional liposomes (~45 h, or plain ropivacaine (~4 h (p <0.05. The pre-formulations tested were significantly less toxic to 3T3 cells, with toxicity increasing in the order: combined system < ropivacaine in donor or acceptor liposomes < ropivacaine in conventional liposomes < plain ropivacaine. The combined formulation, containing 2% ropivacaine, increased the anesthesia duration up to 9 h after subcutaneous infiltration in mice. In conclusion, a promising drug delivery system for ropivacaine was described, which can be loaded with large amounts of the anesthetic (2%, with reduced in vitro cytotoxicity and extended anesthesia time.

  18. Diphenylphenoxy-Thiophene-PDI Dimers as Acceptors for OPV Applications with Open Circuit Voltage Approaching 1 Volt

    Directory of Open Access Journals (Sweden)

    Caterina Stenta

    2018-03-01

    Full Text Available Two new perylenediimides (PDIs have been developed for use as electron acceptors in solution-processed bulk heterojunction solar cells. The compounds were designed to exhibit maximal solubility in organic solvents, and reduced aggregation in the solid state. In order to achieve this, diphenylphenoxy groups were used to functionalize a monomeric PDI core, and two PDI dimers were bridged with either one or two thiophene units. In photovoltaic devices prepared using PDI dimers and a monomer in conjunction with PTB7, it was found that the formation of crystalline domains in either the acceptor or donor was completely suppressed. Atomic force microscopy, X-ray diffraction, charge carrier mobility measurements and recombination kinetics studies all suggest that the lack of crystallinity in the active layer induces a significant drop in electron mobility. Significant surface recombination losses associated with a lack of segregation in the material were also identified as a significant loss mechanism. Finally, the monomeric PDI was found to have sub-optimum LUMO energy matching the cathode contact, thus limiting charge carrier extraction. Despite these setbacks, all PDIs produced high open circuit voltages, reaching almost 1 V in one particular case.

  19. The effect of molecular geometry on the photovoltaic property of diketopyrrolopyrrole based non-fullerene acceptors

    DEFF Research Database (Denmark)

    Zhang, Fei; Brandt, Rasmus Guldbæk; Gu, Zhuowei

    2015-01-01

    The non-fullerene acceptors with different geometric structures have great impact on light absorption, exciton dissociation, and charge transportation in the active layer of organic solar cells (OSCs). In this paper, we designed and synthesized two diketopyrrolopyrrole based non-fullerene acceptors...

  20. Plasmon-enhanced triplet-triplet annihilation upconversion of post-modified polymeric acceptors.

    Science.gov (United States)

    Westbrook, Emily G; Zhang, Peng

    2018-03-15

    We report the localized surface plasmon resonance (LSPR)-enhanced triplet-triplet annihilation upconversion (TTA-UC) of polymeric acceptors containing high percentages of acceptor units. A poly[(methyl methacrylate)-co-(glycidyl methacrylate)] copolymer series with increasing glycidyl methacrylate ratio was prepared using reversible addition-fragmentation chain transfer (RAFT) polymerization. After post-modification of the glycidyl group with anthracene, the acceptor unit, a series of poly[(methyl methacrylate)-co-(2-hydroxypropyl-9-anthroate methacrylate)] (polyACA) was produced with different numbers of acceptor units. These polymeric acceptors were grafted to silver nanoparticles in order to enhance the TTA-UC intensity in the polymers with higher percentages of acceptor units, where concentration quenching usually dominates. With the assistance of the silver nanoparticle LSPR, TTA-UC intensity was enhanced from the polymeric acceptor nanocomposites using platinum octaethylporphyrin as the sensitizer to form the TTA-UC systems. This method is anticipated to improve TTA-UC in the solid-state, where higher percentages of acceptor units are required, but usually cause chromophore concentration quenching, reducing TTA-UC efficiency.

  1. THz emission of donor and acceptor doped GaAs/AlGaAs quantum well structures with inserted thin AlAs monolayer

    Science.gov (United States)

    van Dommelen, Paphavee; Daengngam, Chalongrat; Kalasuwan, Pruet

    2018-04-01

    In this paper, we explore THz range optical intersubband transition energies in a donor doped quantum well of a GaAs/AlGaAs system as a function of the insertion position of an AlAs monolayer in the GaAs quantum well. In simulated models, the optical transition energies between electron subband levels 1 and 2 were higher in the doped structure than in the undoped structure. This may be because the envelope wave function of the second electron subband strongly overlapped the envelope wave function of the first electron subband and influenced the optical intersubband transition between the two levels in the THz range. At different levels of bias voltage at the Schottky barrier on the donor doped structure, the electric field in the growth direction of the structure linearly increased the further away the AlAs monolayer was placed from the reference position. We also simulated the optical transition energies between acceptor energy levels of the acceptor doped structure as a function of the insertion position of the AlAs monolayer. The acceptor doped structure induced THz range emission whereas the undoped structure induced mid-IR emission.

  2. Organic electronic devices with multiple solution-processed layers

    Science.gov (United States)

    Forrest, Stephen R.; Lassiter, Brian E.; Zimmerman, Jeramy D.

    2015-08-04

    A method of fabricating a tandem organic photosensitive device involves depositing a first layer of an organic electron donor type material film by solution-processing of the organic electron donor type material dissolved in a first solvent; depositing a first layer of an organic electron acceptor type material over the first layer of the organic electron donor type material film by a dry deposition process; depositing a conductive layer over the interim stack by a dry deposition process; depositing a second layer of the organic electron donor type material over the conductive layer by solution-processing of the organic electron donor type material dissolved in a second solvent, wherein the organic electron acceptor type material and the conductive layer are insoluble in the second solvent; depositing a second layer of an organic electron acceptor type material over the second layer of the organic electron donor type material film by a dry deposition process, resulting in a stack.

  3. Unsymmetrical donor–acceptor–donor–acceptor type indoline based organic semiconductors with benzothiadiazole cores for solution-processed bulk heterojunction solar cells

    Directory of Open Access Journals (Sweden)

    Wenqin Li

    2017-10-01

    Full Text Available Bulk heterojunction (BHJ solar cells based on small molecules have attracted potential attention due to their promise of conveniently defined structures, high absorption coefficients, solution process-ability and easy fabrication. Three D–A–D–A type organic semiconductors (WS-31, WS-32 and WS-52 are synthesized, based on the indoline donor and benzotriazole auxiliary acceptor core, along with either bare thiophene or rigid cyclopentadithiophene as π bridge, rhodanine or carbonocyanidate as end-group. Their HOMO orbitals are delocalized throughout the whole molecules. Whereas the LUMOs are mainly localized on the acceptor part of structure, which reach up to benzothiadiazole, but no distribution on indoline donor. The first excitations for WS-31 and WS-32 are mainly originated by electron transition from HOMO to LUMO level, while for WS-52, partly related to transition between HOMO and LUMO+1 level. The small organic molecules are applied as donor components in bulk heterojunction (BHJ organic solar cells, using PC61BM as acceptor material to check their photovoltaic performances. The BHJ solar cells based on blended layer of WS-31:PC61BM and WS-32:PC61BM processed with chloroform show overall photoelectric conversion efficiency (PCE of 0.56% and 1.02%, respectively. WS-32 based BHJ solar cells show a higher current density originated by its relatively larger driving force of photo-induced carrier in photo-active layer to LUMO of PC61BM. Keywords: Indoline donor, Unsymmetrical organic semiconductors, BHJ solar cells, Photovoltaic performances

  4. Ab initio nonadiabatic molecular dynamics of the ultrafast electron injection from a PbSe quantum dot into the TiO2 surface.

    Science.gov (United States)

    Long, Run; Prezhdo, Oleg V

    2011-11-30

    Following recent experiments [Science 2010, 328, 1543; PNAS 2011, 108, 965], we report an ab initio nonadiabatic molecular dynamics (NAMD) simulation of the ultrafast photoinduced electron transfer (ET) from a PbSe quantum dot (QD) into the rutile TiO(2) (110) surface. The system forms the basis for QD-sensitized semiconductor solar cells and demonstrates that ultrafast interfacial ET is instrumental for achieving high efficiencies in solar-to-electrical energy conversion. The simulation supports the observation that the ET successfully competes with energy losses due to electron-phonon relaxation. The ET proceeds by the adiabatic mechanism because of strong donor-acceptor coupling. High frequency polar vibrations of both QD and TiO(2) promote the ET, since these modes can rapidly influence the donor-acceptor state energies and coupling. Low frequency vibrations generate a distribution of initial conditions for ET, which shows a broad variety of scenarios at the single-molecule level. Compared to the molecule-TiO(2) interfaces, the QD-TiO(2) system exhibits pronounced differences that arise due to the larger size and higher rigidity of QDs relative to molecules. Both donor and acceptor states are more delocalized in the QD system, and the ET is promoted by optical phonons, which have relatively low frequencies in the QD materials composed of heavy elements. In contrast, in molecular systems, optical phonons are not thermally accessible under ambient conditions. Meanwhile, TiO(2) acceptor states resemble surface impurities due to the local influence of molecular chromophores. At the same time, the photoinduced ET at both QD-TiO(2) and molecule-TiO(2) interfaces is ultrafast and occurs by the adiabatic mechanism, as a result of strong donor-acceptor coupling. The reported state-of-the-art simulation generates a detailed time-domain atomistic description of the interfacial ET process that is fundamental to a wide variety of applications.

  5. Proteome-Wide Identification of In Vivo ADP-Ribose Acceptor Sites by Liquid Chromatography-Tandem Mass Spectrometry

    DEFF Research Database (Denmark)

    Larsen, Sara C; Leutert, Mario; Bilan, Vera

    2017-01-01

    remained a difficult challenge. Here, we describe a detailed protocol for unbiased analysis of ADP-ribosylated proteins and their ADP-ribose acceptor sites under physiological conditions. The method relies on the enrichment of mono-ADP-ribosylated peptides using the macrodomain Af1521 in combination...... with liquid chromatography-high-resolution tandem MS (LC-MS/MS). The 5-day protocol explains the step-by-step enrichment and identification of ADP-ribosylated peptides from cell culture stage all the way through to data processing using the MaxQuant software suite....

  6. Discussion and analytical test for inclusion of advanced field and boundary condition in theory of free electron lasers

    Science.gov (United States)

    Niknejadi, Pardis; Madey, John M. J.

    2017-09-01

    By the covariant statement of the distance in space-time separating transmitter and receivers, the emission and absorption of the retarded and advanced waves are all simultaneous. In other words, for signals carried on electromagnetic waves (advanced or retarded) the invariant interval (cdt) 2 -dr2 between the emission of a wave and it's absorption at the non-reflecting boundary is always identically zero. Utilizing this principle, we have previously explained the advantages of including the coherent radiation reaction force as a part of the solution to the boundary value problem for FELs that radiate into "free space" (Self Amplified Spontaneous Emission (SASE) FELs) and discussed how the advanced field of the absorber can interact with the radiating particles at the time of emission. Here we present an analytical test which verifies that a multilayer mirror can act as a band pass filter and can contribute to microbunching in the electron beam. Here we will discuss motivation, conditions and requirements, and method for testing this effect.

  7. On the Importance of Nonbonding Donor-Acceptor Interactions Involving PO2. Radicals: An ab Initio Study.

    Science.gov (United States)

    Bauzá, Antonio; Frontera, Antonio

    2017-08-18

    In this study, several σ-type and π-hole bonding complexes between PO 2 . radicals and electron-rich entities have been optimized at the RI-MP2/aug-cc-pVQZ level of theory. We have used Cl - , Br - , I - anions, and ethene, ethyne, HCN, HF, and H 2 O as Lewis bases. In addition, we have performed natural bond orbital (NBO) and Mulliken spin density analyses, highlighting the donor-acceptor nature of the interaction. Moreover, an interesting retro-donation from the single electron lone pair of the PO 2 . radical to the Lewis base also contributes to the stabilization of the complexes studied herein. Finally, the Bader's atoms-in-molecules (AIM) analysis of several complexes has been performed to further characterize the interactions discussed herein. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads

    KAUST Repository

    Jiang, Junlin

    2017-05-25

    A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers.

  9. Dual acceptor doping and aging effect of p-ZnO:(Na, N) nanorod thin films by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Swapna, R., E-mail: swapna.ramella@yahoo.com, E-mail: santhoshmc@nitt.edu; Amiruddin, R., E-mail: swapna.ramella@yahoo.com, E-mail: santhoshmc@nitt.edu; Santhosh Kumar, M. C., E-mail: swapna.ramella@yahoo.com, E-mail: santhoshmc@nitt.edu [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli-620 015 (India)

    2014-01-28

    An attempt has been made to realize p-type ZnO by dual acceptor doping (Na-N) into ZnO thin films. Na and N doped ZnO thin films of different concentrations (0 to 8 at.%) have been grown by spray pyrolysis at 623 K. The grown films on glass substrate have been characterized by X-ray diffraction (XRD), Hall measurement, UV-Vis spectrophotometer, Photoluminescence (PL) and Energy dispersive spectroscopy (EDS) to validate the p-type conduction. The surface morphology and roughness of the ZnO:(Na, N) films are studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Hall measurement shows that all the films exhibit p-type conductivity except for 0 at.% Na-N doped ZnO film. The obtained resistivity (5.60×10{sup −2} Ω cm) and hole concentration (3.15×10{sup 18} cm{sup −3}) for the best dual acceptor doped film is 6 at.%. It has been predicted that (Na{sub Zn}−N{sub O}) acceptor complex is responsible for the p-type conduction. The p-type conductivity of the ZnO:(Na, N) films is stable even after 6 months. The crystallinity of the films has been studied by XRD. Energy dispersive spectroscopy (EDS) confirms the presence of Na and N in 6 at.% ZnO:(Na, N) film. Photoluminescence (PL) spectra of ZnO:(Na, N) films show NBE and deep level emissions in the UV and visible regions, respectively. The ZnO:(Na, N) films exhibit a high transmittance about 90% in the visible region.

  10. The nitrogen acceptor in 2H-Polytype synthetic MoS2. Frequency and temperature dependent ESR analysis

    International Nuclear Information System (INIS)

    Schoenaers, Ben; Stesmans, Andre; Afanas'ev, Valery V.

    2017-01-01

    In extending on recent electron spin resonance (ESR) work which has revealed the N acceptor (N substituting for S site) in 2H-polytype bulk synthetic MoS 2 , the dopant is extensively analyzed in terms of its frequency, temperature (T), and magnetic field B angular dependent ESR spectral characteristics. For B parallel c-axis, the multi-frequency analysis confirms the ESR spectrum as being composed of a 14 N hyperfine (hf) triplet with hf splitting constant A parallel = 14.7 ± 0.2 G (B parallel c-axis) and making up ∼74% of the total spectrum intensity, superimposed on a central line centered at about equal g-value [g parallel = 2.032(2)]. The presence of the latter signal, points to some non-uniformity in dopant distribution, that is, clustering, with about ∼26% of the total N response not originating from N incorporated in the preferred ''isolated'' dopant configuration. Angular dependent measurements reveal distinct anisotropy of the hf matrix, whereas ESR probing over a wide T-range exposes drastic signal broadening with increasing T above ∼150 K. Detailed study of the N acceptor signal intensity versus T at Q-band reveals an activation energy E a = 50 ± 10 meV, herewith consolidating the value reported initially. Besides unveiling the S-site substitutional N impurity as an appropriate p-type dopant for MoS 2 , the total of the ESR work establishes a basic frame of the N acceptor ESR characteristics, giving way for further in-depth theoretical perusal. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. ELECTRON HEATING BY THE ION CYCLOTRON INSTABILITY IN COLLISIONLESS ACCRETION FLOWS. II. ELECTRON HEATING EFFICIENCY AS A FUNCTION OF FLOW CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Sironi, Lorenzo, E-mail: lsironi@cfa.harvard.edu [NASA Einstein Postdoctoral Fellow. (United States)

    2015-02-20

    In the innermost regions of low-luminosity accretion flows, including Sgr A* at the center of our Galaxy, the frequency of Coulomb collisions is so low that the plasma has two temperatures, with the ions substantially hotter than the electrons. This paradigm assumes that Coulomb collisions are the only channel for transferring the ion energy to the electrons. In this work, the second of a series, we assess the efficiency of electron heating by ion velocity-space instabilities in collisionless accretion flows. The instabilities are seeded by the pressure anisotropy induced by magnetic field amplification, coupled to the adiabatic invariance of the particle magnetic moments. Using two-dimensional particle-in-cell (PIC) simulations, we showed in Paper I that if the electron-to-ion temperature ratio is T {sub 0e}/T {sub 0i} ≲ 0.2, the ion cyclotron instability is the dominant mode for ion betas β{sub 0i} ∼ 5-30 (here, β{sub 0i} is the ratio of ion thermal pressure to magnetic pressure), as appropriate for the midplane of low-luminosity accretion flows. In this work, we employ analytical theory and one-dimensional PIC simulations (with the box aligned with the fastest-growing wave vector of the ion cyclotron mode) to fully characterize how the electron heating efficiency during the growth of the ion cyclotron instability depends on the electron-to-proton temperature ratio, the plasma beta, the Alfvén speed, the amplification rate of the mean field (in units of the ion Larmor frequency), and the proton-to-electron mass ratio. Our findings can be incorporated as a physically grounded subgrid model into global fluid simulations of low-luminosity accretion flows, thus helping to assess the validity of the two-temperature assumption.

  12. Analysis of nonlinear optical properties in donor–acceptor materials

    International Nuclear Information System (INIS)

    Day, Paul N.; Pachter, Ruth; Nguyen, Kiet A.

    2014-01-01

    Time-dependent density functional theory has been used to calculate nonlinear optical (NLO) properties, including the first and second hyperpolarizabilities as well as the two-photon absorption cross-section, for the donor-acceptor molecules p-nitroaniline and dimethylamino nitrostilbene, and for respective materials attached to a gold dimer. The CAMB3LYP, B3LYP, PBE0, and PBE exchange-correlation functionals all had fair but variable performance when compared to higher-level theory and to experiment. The CAMB3LYP functional had the best performance on these compounds of the functionals tested. However, our comprehensive analysis has shown that quantitative prediction of hyperpolarizabilities is still a challenge, hampered by inadequate functionals, basis sets, and solvation models, requiring further experimental characterization. Attachment of the Au 2 S group to molecules already known for their relatively large NLO properties was found to further enhance the response. While our calculations show a modest enhancement for the first hyperpolarizability, the enhancement of the second hyperpolarizability is predicted to be more than an order of magnitude

  13. Constraint-based modeling of carbon fixation and the energetics of electron transfer in Geobacter metallireducens.

    Directory of Open Access Journals (Sweden)

    Adam M Feist

    2014-04-01

    Full Text Available Geobacter species are of great interest for environmental and biotechnology applications as they can carry out direct electron transfer to insoluble metals or other microorganisms and have the ability to assimilate inorganic carbon. Here, we report on the capability and key enabling metabolic machinery of Geobacter metallireducens GS-15 to carry out CO2 fixation and direct electron transfer to iron. An updated metabolic reconstruction was generated, growth screens on targeted conditions of interest were performed, and constraint-based analysis was utilized to characterize and evaluate critical pathways and reactions in G. metallireducens. The novel capability of G. metallireducens to grow autotrophically with formate and Fe(III was predicted and subsequently validated in vivo. Additionally, the energetic cost of transferring electrons to an external electron acceptor was determined through analysis of growth experiments carried out using three different electron acceptors (Fe(III, nitrate, and fumarate by systematically isolating and examining different parts of the electron transport chain. The updated reconstruction will serve as a knowledgebase for understanding and engineering Geobacter and similar species.

  14. Impact of Nonfullerene Acceptor Core Structure on the Photophysics and Efficiency of Polymer Solar Cells

    KAUST Repository

    Alamoudi, Maha

    2018-03-02

    Small-molecule “nonfullerene” acceptors are promising alternatives to fullerene (PC61/71BM) derivatives often used in bulk heterojunction (BHJ) organic solar cells; yet, the efficiency-limiting processes and their dependence on the acceptor structure are not clearly understood. Here, we investigate the impact of the acceptor core structure (cyclopenta-[2,1-b:3,4-b′]dithiophene (CDT) versus indacenodithiophene (IDTT)) of malononitrile (BM)-terminated acceptors, namely CDTBM and IDTTBM, on the photophysical characteristics of BHJ solar cells. Using PCE10 as donor polymer, the IDTT-based acceptor achieves power conversion efficiencies (8.4%) that are higher than those of the CDT-based acceptor (5.6%) because of a concurrent increase in short-circuit current and open-circuit voltage. Using (ultra)fast transient spectroscopy we demonstrate that reduced geminate recombination in PCE10:IDTTBM blends is the reason for the difference in short-circuit currents. External quantum efficiency measurements indicate that the higher energy of interfacial charge-transfer states observed for the IDTT-based acceptor blends is the origin of the higher open-circuit voltage.

  15. Investigating charge generation in polymer:non-fullerene acceptor bulk heterojunction films

    Energy Technology Data Exchange (ETDEWEB)

    Stoltzfus, Dani M.; Larson, Bryon W.; Zarrabi, Nasim; Shaw, Paul E.; Clulow, Andrew J.; Jin, Hui; Burn, Paul L.; Gentle, Ian R.; Kopidakis, Nikos

    2018-04-01

    Non-fullerene acceptors are now capable of being used in high efficiency bulk heterojunction (BHJ) donor-acceptor organic solar cells. Acceptors comprising single or multiple linked chromophores have been used. We have developed a new non-fullerene molecular acceptor as well as two non-polymeric macromolecular materials that contain four equivalents of a similar chromophore, but can adopt different spatial arrangements of the chromophores. We compare the effect of having single and multiple chromophores within a macromolecule on the charge generation processes in P3HT:non-fullerene acceptor BHJ films using Transient Absorption Spectroscopy (TAS) and Time Resolved Microwave Conductivity (TRMC) measurements. It was found from the TAS measurements that at low weight percent (5 wt%) the single chromophore formed more polarons than the acceptors in which chromophores were linked, due to it having a more even distribution within the film. At higher concentrations (50 wt%) the trend was reversed due to the single chromophore forming crystalline domains, which reduced the interface area with the P3HT donor. The TRMC measurements showed that more mobile carriers were formed in the macromolecular acceptors when used at low concentrations in the blend and, independent of concentration, mobile carriers had a longer lifetime when compared to films containing the molecular material, which we ascribe to the charges being able to sample more than one chromophore and thus reduce recombination events.

  16. Advances in electron transfer chemistry

    CERN Document Server

    Mariano, Patrick S

    1993-01-01

    Advances in Electron Transfer Chemistry, Volume 3 presents studies that discuss findings in the various aspects of electron chemistry. The book is comprised of four chapters; each chapter reviews a work that tackles an issue in electron transfer chemistry. Chapter 1 discusses the photoinduced electron transfer in flexible biaryl donor-acceptor molecules. Chapter 2 tackles light-induced electron transfer in inorganic systems in homogeneous and heterogeneous phases. The book also covers internal geometry relaxation effects on electron transfer rates of amino-centered systems. The sequential elec

  17. Intercomparison of peroxy radical measurements obtained at atmospheric conditions by laser-induced fluorescence and electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Hofzumahaus

    2009-03-01

    Full Text Available Measurements of hydroperoxy radical (HO2 and organic peroxy radical (RO2 concentrations were performed by two different techniques in the atmospheric simulation chamber SAPHIR in Jülich, Germany. The first technique was the well-established Matrix Isolation Electron Spin Resonance (MIESR, which provides absolute measurements with a time resolution of 30 min and high accuracy (10%, 2 σ. The other technique, ROxLIF, has been newly developed. It is based on the selective chemical conversion of ROx radicals (HO2 and RO2 to OH, which is detected with high sensitivity by laser-induced fluorescence (LIF. ROxLIF is calibrated by quantitative photolysis of water vapor at 185 nm and provides ambient measurements at a temporal resolution of 1 min and accuracy of 20% (2 σ. The measurements of HO2 and RO2 obtained by the two techniques were compared for two types of atmospheric simulation experiments. In one experiment, HO2 and CH3O2 radicals were produced by photooxidation of methane in air at tropospheric conditions. In the second experiment, HO2 and C2H5O2 were produced by ozonolysis of 1-butene in air at dark conditions. The radical concentrations were within the range of 16 to 100 pptv for HO2 and 12 to 45 pptv for RO2. Good agreement was found in the comparison of the ROxLIF and MIESR measurements within their combined experimental uncertainties. Linear regressions to the combined data set yield slopes of 1.02±0.13 (1 σ for RO2 and 0.98±0.08 (1 σ for HO2 without significant offsets. The results confirm the calibration of the ROxLIF instrument and demonstrate that it can be applied with good accuracy for measurements of atmospheric peroxy radical concentrations.

  18. Fluorine as a hydrogen-bond acceptor: experimental evidence and computational calculations.

    Science.gov (United States)

    Dalvit, Claudio; Invernizzi, Christian; Vulpetti, Anna

    2014-08-25

    Hydrogen-bonding interactions play an important role in many chemical and biological systems. Fluorine acting as a hydrogen-bond acceptor in intermolecular and intramolecular interactions has been the subject of many controversial discussions and there are different opinions about it. Recently, we have proposed a correlation between the propensity of fluorine to be involved in hydrogen bonds and its (19)F NMR chemical shift. We now provide additional experimental and computational evidence for this correlation. The strength of hydrogen-bond complexes involving the fluorine moieties CH2F, CHF2, and CF3 was measured and characterized in simple systems by using established and novel NMR methods and compared to the known hydrogen-bond complex formed between acetophenone and p-fluorophenol. Implications of these results for (19)F NMR screening are analyzed in detail. Computed values of the molecular electrostatic potential at the different fluorine atoms and the analysis of the electron density topology at bond critical points correlate well with the NMR results. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Optical Excitation in Donor-Pt-Acceptor Complexes: Role of the Structure.

    Science.gov (United States)

    Gong, Zu-Yong; Duan, Sai; Tian, Guangjun; Zhang, Guozhen; Jiang, Jun; Luo, Yi

    2016-05-26

    The optical properties of the Pt complexes in the form of donor-metal-acceptor (D-M-A) were studied at the first-principles level. Calculated results show that for the frontier molecular orbitals (MOs) of a D-M-A structure the energies of unoccupied frontier MO can be mainly determined by the interaction between M and A, whereas the M-A and M-D interactions both determine the energies of occupied frontier MO. By developing a straightforward transition dipole decomposition method, we found that not only the local excitations in D but also those in A can significantly contribute to the charge-transfer (CT) excitation. Furthermore, the calculations also demonstrate that by tuning the dihedral angle between D and A the transition probability can be precisely controlled so as to broaden the spectrum region of photoabsorption. For the D-M-A molecule with a delocalized π system in A, the CT excitation barely affects the electronic structures of metal, suggesting that the oxidation state of the metal can be kept during the excitation. These understandings for the optical properties of the D-M-A molecule would be useful for the design of dye-sensitized solar cells, photocatalysis, and luminescence systems.

  20. Design of Bicontinuous Donor/Acceptor Morphologies for Use as Organic Solar Cell Active Layers

    Science.gov (United States)

    Kipp, Dylan; Mok, Jorge; Verduzco, Rafael; Ganesan, Venkat

    Two of the primary challenges limiting the marketability of organic solar cells are i) the smaller device efficiency of the organic solar cell relative to the conventional silicon-based solar cell and ii) the long term thermal instability of the device active layer. The achievement of equilibrium donor/acceptor morphologies with the characteristics believed to yield high device performance characteristics could address each of these two challenges. In this work, we present the results of a combined simulations and experiments-based approach to investigate if a conjugated BCP additive can be used to control the self-assembled morphologies taken on by conjugated polymer/PCBM mixtures. First, we use single chain in mean field Monte Carlo simulations to identify regions within the conjugated polymer/PCBM composition space in which addition of copolymers can lead to bicontinuous equilibrium morphologies with high interfacial areas and nanoscale dimensions. Second, we conduct experiments as directed by the simulations to achieve such morphologies in the PTB7 + PTB7- b-PNDI + PCBM model blend. We characterize the results of our experiments via a combination of transmission electron microscopy and X-ray scattering techniques and demonstrate that the morphologies from experiments agree with those predicted in simulations. Accordingly, these results indicate that the approach utilized represents a promising approach to intelligently design the morphologies taken on by organic solar cell active layers.

  1. New Type of Donor-Acceptor Through-Space Conjugated Polymer

    Directory of Open Access Journals (Sweden)

    Lin Lin

    2010-01-01

    Full Text Available We report the synthesis and properties of a novel through-space conjugated polymer with a [2.2]paracyclophane skeleton. The obtained polymer possessed donor (fluorene and acceptor (2,1,3-benzothiadiazole segments that were alternately π-stacked in proximity via the [2.2]paracyclophane moieties. The good overlap between the emission peak of the donor unit (fluorene and the CT band of the acceptor unit (2,1,3-benzothiadiazole caused fluorescence resonance energy transfer, and the visible green light emission from the acceptor unit was observed.

  2. Diffusion of acceptors in n-type and semi-insulating InP

    Science.gov (United States)

    Tuck, Brian

    2000-01-01

    When acceptors diffuse into an n-type semiconductor, both the surface concentration and the diffusion depth of the diffusant are influenced by the initial donor concentration. Similar interaction is observed between shallow acceptors and deep acceptors. Previous work describing the diffusion of zinc during MOCVD growth of InP is reviewed and compared to the diffusion of both zinc and cadmium into InP from the vapour phase. Interdiffusion between iron- and zinc-doped MOCVD layers is also considered. It is shown that these experiments can all be explained by a simple model involving Fermi level effects.

  3. The Simulation of Energy Distribution of Electrons Detected by Segmental Ionization Detector in High Pressure Conditions of ESEM

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém; Konvalina, Ivo; Oral, Martin; Hudec, Jiří

    2015-01-01

    Roč. 21, S4 (2015), s. 264-269 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-22777S Institutional support: RVO:68081731 Keywords : electron -gas interactions * Monte Carlo simulation * signal amplification * segmented ionization detector Subject RIV: JA - Electron ics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  4. 78 FR 11553 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Electronic Flight Control System...

    Science.gov (United States)

    2013-02-19

    ... adequacy under Sec. 611 of Public Law 92-574, the ``Noise Control Act of 1972.'' The FAA issues special...; Electronic Flight Control System: Control Surface Awareness and Mode Annunciation AGENCY: Federal Aviation...) associated with the control surface awareness and mode annunciation of the electronic flight control system...

  5. A novel donor-acceptor polymeric electrochromic material containing carbazole and 1,8-naphtalimide as subunit

    International Nuclear Information System (INIS)

    Koyuncu, Fatma Baycan; Koyuncu, Sermet; Ozdemir, Eyup

    2010-01-01

    We report here the synthesis of a novel polymeric electrochromic material containing carbazole (Cbz)-donor and 1,8-napthalimide-acceptor as subunit. The band gap E g was measured using UV-vis spectroscopy and compared with that obtained by cyclic voltammetry (CV). Due to intramolecular electron transfer from Cbz-donor to 1,8-napthalimide-acceptor, the fluorescence quenching was observed. When the spectro-electrochemical and electrochromic properties of polymer film were investigated, various tones of green color were obtained on the polymeric film. In the positive regime, the polymer film obtained thereby is dark green resulting from the association of carbazolylium cation radicals at oxidized state and then it can be bleached by electrochemical reduction. Besides, in the negative regime, yellowish green color of film converted to blue attributed to reduction of the 1,8-napthalimide moiety. Finally, the polymeric electrochromic exhibits multi-electrochromic behavior, high redox stability, high coloration efficiency and reasonable response time.

  6. Micro-electromembrane extraction using multiple free liquid membranes and acceptor solutions - Towards selective extractions of analytes based on their acid-base strength.

    Science.gov (United States)

    Kubáň, Pavel; Seip, Knut Fredrik; Gjelstad, Astrid; Pedersen-Bjergaard, Stig

    2016-11-02

    This work investigated selective micro-electromembrane extractions (μ-EMEs) of the colored indicators metanil yellow and congo red (visual proof-of-principle) and the small drug substances nortriptyline, papaverine, mianserin, and citalopram (model analytes) based on their acid-base strength. With two free liquid membranes (FLMs), the target analytes were extracted from aqueous donor solution, across FLM 1 (1-pentanol, 1-ethyl-2-nitrobenzene (ENB) or 4-nitrocumene (4-NC)), into aqueous acceptor solution 1, further across FLM 2 (1-pentanol, ENB or 4-NC), and finally into aqueous acceptor solution 2. All phases had volumes between 1.0 and 1.5 μL and extractions were promoted by 200-300 V d.c. applied across the five-phase μ-EME system formed in a perfluoroalkoxy capillary tubing. The anode was located in acceptor solution 2 and the cathode was located in donor solution for μ-EMEs of acidic analytes, and locations of the electrodes were vice versa for μ-EMEs of basic analytes. After μ-EME, donor solution and acceptor solution 1 and 2 were analyzed by capillary electrophoresis or liquid chromatography-mass spectrometry. The model analytes migrated efficiently in the proposed μ-EME system, their migration behavior was controlled by pH in aqueous solutions and their selective fractionation into acceptor solution 1 and 2 was demonstrated based on their acid-base strength. Under optimal conditions, acceptor solution 2 contained 60% nortriptyline (pK a  = 10.5) and less than 1% papaverine (pK a  = 6.0) and acceptor solution 1 contained 17% nortriptyline and 27% papaverine after 15 min of μ-EME. The five-phase μ-EME system was also compatible with human plasma samples. Work is in progress to further increase the fractionation capability, and to implement the concept into microfluidic platforms. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Highly Efficient Inverted D:A1:A2Ternary Blend Organic Photovoltaics Combining a Ladder-type Non-Fullerene Acceptor and a Fullerene Acceptor.

    Science.gov (United States)

    Chang, Shao-Ling; Cao, Fong-Yi; Huang, Wen-Chia; Huang, Po-Kai; Hsu, Chain-Shu; Cheng, Yen-Ju

    2017-07-26

    A formylated benzodi(cyclopentadithiophene) (BDCPDT) ladder-type structure with forced coplanarity is coupled with two 1,1-dicyanomethylene-3-indanone (IC) moieties via olefination to form a non-fullerene acceptor, BDCPDT-IC. The BDCPDT-IC, as an acceptor (A 1 ) with broad light-absorbing ability and excellent solution processability, is combined with a second PC 71 BM acceptor (A 2 ) and a medium band gap polymer, PBDB-T, as the donor (D) to form a ternary blend with gradient HOMO/LUMO energy alignments and panchromatic absorption. The device with the inverted architecture using the D:A 1 :A 2 ternary blend has achieved a highest efficiency of 9.79% with a superior J sc of 16.84 mA cm -2 .

  8. Ground-state kinetics of bistable redox-active donor-acceptor mechanically interlocked molecules.

    Science.gov (United States)

    Fahrenbach, Albert C; Bruns, Carson J; Li, Hao; Trabolsi, Ali; Coskun, Ali; Stoddart, J Fraser

    2014-02-18

    The ability to design and confer control over the kinetics of theprocesses involved in the mechanisms of artificial molecular machines is at the heart of the challenge to create ones that can carry out useful work on their environment, just as Nature is wont to do. As one of the more promising forerunners of prototypical artificial molecular machines, chemists have developed bistable redox-active donor-acceptor mechanically interlocked molecules (MIMs) over the past couple of decades. These bistable MIMs generally come in the form of [2]rotaxanes, molecular compounds that constitute a ring mechanically interlocked around a dumbbell-shaped component, or [2]catenanes, which are composed of two mechanically interlocked rings. As a result of their interlocked nature, bistable MIMs possess the inherent propensity to express controllable intramolecular, large-amplitude, and reversible motions in response to redox stimuli. In this Account, we rationalize the kinetic behavior in the ground state for a large assortment of these types of bistable MIMs, including both rotaxanes and catenanes. These structures have proven useful in a variety of applications ranging from drug delivery to molecular electronic devices. These bistable donor-acceptor MIMs can switch between two different isomeric states. The favored isomer, known as the ground-state co-conformation (GSCC) is in equilibrium with the less favored metastable state co-conformation (MSCC). The forward (kf) and backward (kb) rate constants associated with this ground-state equilibrium are intimately connected to each other through the ground-state distribution constant, KGS. Knowing the rate constants that govern the kinetics and bring about the equilibration between the MSCC and GSCC, allows researchers to understand the operation of these bistable MIMs in a device setting and apply them toward the construction of artificial molecular machines. The three biggest influences on the ground-state rate constants arise from

  9. Donor-acceptor random copolyesters containing perylenebisimide (PBI) and oligo(p-phenylene vinylene) (OPV) by melt condensation polymerization: energy transfer studies.

    Science.gov (United States)

    Nisha, S Kumari; Asha, S K

    2013-10-31

    Novel copolyesters consisting of oligo(p-phenylene vinylene) (OPV) as donor (D) and perylenebisimide (PBI) as acceptor (A) were synthesized by melt polycondensation. Photoinduced energy transfer and photoinduced charge separation in these polyesters were studied in solution as well as in the solid state. Selective excitation of OPV moiety resulted in the energy transfer with >90% efficiency from OPV to PBI chromophore in the solution state. The direct excitation of PBI in the D-A copolyester resulted in reduced fluorescence emission of acceptor, indicating electron transfer between the D and A moieties. The effect of distance between donor and acceptor on the energy transfer efficiency from donor to acceptor was studied. Compared to a physical mixture of D and A polyesters alone, the energy transfer was 4 times more efficient in the D-A copolyester, highlighting the influence of covalently linking D and A in a single polymer chain. A strong fluorescence quenching (∼ 100%) of both chromophores in solid state indicated an efficient photoinduced charge transfer after photoexcitation of either D or A. Thus, OPV-PBI main chain copolyester is an excellent system for the study of energy- and electron-transfer processes in organic semiconductor. Reactive blend of D/A copolyester was also prepared by the transesterification reaction between D and A alone copolyesters. The energy transfer efficiency from D to A moiety upon selective excitation of D chromophore in the D/A copolyester blend was ∼4 times higher compared to a physical mixture of D and A alone copolyesters, which gave direct proof for the transesterification reaction in polyester/polyester reactive blending.

  10. Direct Observation of a Photochemical Alkyne-Allene Reaction and of a Twisted and Rehybridized Intramolecular Charge-Transfer State in a Donor-Acceptor Dyad.

    Science.gov (United States)

    Dereka, Bogdan; Svechkarev, Denis; Rosspeintner, Arnulf; Tromayer, Maximilian; Liska, Robert; Mohs, Aaron M; Vauthey, Eric

    2017-11-22

    The excited-state dynamics of an aniline-triazine electron donor-acceptor dyad with an alkyne spacer has been investigated using a combination of ultrafast broadband mid-IR and visible transient absorption and fluorescence spectroscopies. The transient IR data reveal the occurrence of an efficient alkyne to allene isomerization of the spacer with a time constant increasing from a few hundreds of femtoseconds to a few picoseconds with solvent viscosity. This process is faster than the vibrational cooling of the Franck-Condon excited state, indicative of nonequilibrium dynamics. The transient electronic absorption and fluorescence data evidence that this transformation is accompanied by a charge separation between the donor and the acceptor subunits. The allene character of the spacer implies an orthogonal orientation of the donor and acceptor moieties, similar to that proposed for twisted intramolecular charge-transfer states. Such states are often invoked in the excited-state dynamics of donor-acceptor dyads, but their involvement could never be unambiguously evidenced spectroscopically. The alkyne-allene isomerization involves not only a torsional motion but also a bending of the molecule due to the sp to sp 2 rehybridization of one of the alkyne carbon atoms. This twisted and rehybridized intramolecular charge transfer ("TRICT") state decays back to the planar and linear alkyne ground state on a time scale decreasing from a few hundred to ten picoseconds upon going from weakly to highly polar solvents. The different solvent dependencies reveal that the dynamics of the allene buildup are controlled by the structural changes, whereas the decay is limited by the charge recombination step.

  11. In situ X-ray ptychography imaging of high-temperature CO2 acceptor particle agglomerates

    DEFF Research Database (Denmark)

    Høydalsvik, Kristin; Fløystad, Jostein Bø; Zhao, Tiejun

    2014-01-01

    Imaging nanoparticles under relevant reaction conditions of high temperature and gas pressure is difficult because conventional imaging techniques, like transmission electron microscopy, cannot be used. Here we demonstrate that the coherent diffractive imaging technique of X-ray ptychography can ...

  12. Electron reactions in model liquids and biological systems

    International Nuclear Information System (INIS)

    Bakale, G.; Gregg, E.C.

    1982-01-01

    Progress is reported in the following studies: (1) Field-dependent electron attachment; (2) Dependence of electron attachment rate on electron-acceptor dipole moment; (3) Electron attachment in i-octane/TMS mixtures; (4) Electron attachment/detachment equilibria; (5) Electron attachment to reversed micelles; (6) Electron attachment to chemical carcinogens; (7) Radiation-induced bacterial mutagenesis; and (8) Bacterial mutagenicity of nitrobenzene derivatives. 14 references

  13. Conditioning of Si-interfaces by wet-chemical oxidation: Electronic interface properties study by surface photovoltage measurements

    Science.gov (United States)

    Angermann, Heike

    2014-09-01

    The field-modulated surface photovoltage (SPV) method, a very surface sensitive technique, was utilized to determine electronic interface properties on wet-chemically oxidized and etched silicon (Si) interfaces. The influence of preparation-induced surface micro-roughness and un-stoichiometric oxides on the resulting the surface charge, energetic distribution Dit(E), and density Dit,min of rechargeable states was studied by simultaneous, spectroscopic ellipsometry (SE) measurements on polished Si(111) and Si(100) substrates. Based on previous findings and new research, a study of conventional and newly developed wet-chemical oxidation methods was established, correlating the interactions between involved oxidizing and etching solutions and the initial substrate morphology to the final surface conditioning. It is shown, which sequences of wet-chemical oxidation and oxide removal, have to be combined in order to achieve atomically smooth, hydrogen terminated surfaces, as well as ultra-thin oxide layers with low densities of rechargeable states on flat, saw damage etched, and textured Si substrates, as commonly applied in silicon device and solar cell manufacturing. These conventional strategies for wet-chemical pre-treatment are mainly based on concentrated solutions. Therefore, special attention was put on the development of more environmentally acceptable processes, utilizing e.g. hot pure water with low contents of oxygen or hydrochloric acid, and of ozone, working at ambient temperatures. According to our results, these methods could be a high quality and low cost alternative to current approaches with liquid chemicals for the preparation of hydrophobic Si substrate surfaces and ultra-thin passivating oxide layers. As demonstrated for selected examples, the effect of optimized wet-chemical pre-treatments can be preserved during subsequent soft plasma enhanced chemical vapor depositions of Si oxides (SiOx), or amorphous materials such as Si (a-Si:H), Si nitride (a

  14. 78 FR 76251 - Special Conditions: Airbus, Model A350-900 Series Airplane; Electronic System Security Protection...

    Science.gov (United States)

    2013-12-17

    ... functions. However, electronic system network security considerations and functions have played a relatively... network configuration may allow the exploitation of network security vulnerabilities resulting in... System Security Protection From Unauthorized External Access AGENCY: Federal Aviation Administration (FAA...

  15. 77 FR 69573 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Electronic Flight Control System...

    Science.gov (United States)

    2012-11-20

    ... provides. Using the search function of the docket web site, anyone can find and read the electronic form of... that the pilot is not confused and led to take inappropriate recovery action if multiple warnings occur...

  16. Alternansucrase acceptor reactions with D-tagatose and L-glucose.

    Science.gov (United States)

    Côté, Gregory L; Dunlap, Christopher A; Appell, Michael; Momany, Frank A

    2005-02-07

    Alternansucrase (EC 2.4.1.140) is a d-glucansucrase that synthesizes an alternating alpha-(1-->3), (1-->6)-linked d-glucan from sucrose. It also synthesizes oligosaccharides via d-glucopyranosyl transfer to various acceptor sugars. Two of the more efficient monosaccharide acceptors are D-tagatose and L-glucose. In the presence of d-tagatose, alternansucrase produced the disaccharide alpha-d-glucopyranosyl-(1-->1)-beta-D-tagatopyranose via glucosyl transfer. This disaccharide is analogous to trehalulose. We were unable to isolate a disaccharide product from L-glucose, but the trisaccharide alpha-D-glucopyranosyl-(1-->6)-alpha-d-glucopyranosyl-(1-->4)-l-glucose was isolated and identified. This is analogous to panose, one of the structural units of pullulan, in which the reducing-end D-glucose residue has been replaced by its L-enantiomer. The putative L-glucose disaccharide product, produced by glucoamylase hydrolysis of the trisaccharide, was found to be an acceptor for alternansucrase. The disaccharide, alpha-D-glucopyranosyl-(1-->4)-L-glucose, was a better acceptor than maltose, previously the best known acceptor for alternansucrase. A structure comparison of alpha-D-glucopyranosyl-(1-->4)-L-glucose and maltose was performed through computer modeling to identify common features, which may be important in acceptor affinity by alternansucrase.

  17. Petroleum hydrocarbon biodegradation under mixed denitrifying/microaerophilic conditions

    International Nuclear Information System (INIS)

    Miller, D.E.; Hutchins, S.R.

    1995-01-01

    Data are presented for aqueous-flow, soil-column microcosms in which removal of benzene, toluene, ethylbenzene, and xylenes (BTEX) is observed for two operating conditions: (1) nitrate, 25 to 26 mg(N)/L, as the single electron acceptor and (2) nitrate, 27 to 28 mg(N)/L combined with low levels of oxygen, 0.8 to 1.2 mg O 2 /L. Soils used in this study include aquifer material from Traverse City, Michigan; Park City, Kansas; and Eglin Air Force Base (AFB), Florida. BTEX compounds are introduced at concentrations ranging from 2.5 to 5 mg/L, with total BTEX loading from 20 to 22 mg/L Complete removal of toluene and partial removal of ethylbenzene, m-xylene, and o-xylene were observed for all soils during trials in which nitrate was the only electron acceptor. Combining low levels of oxygen with nitrate produced varying effects on BTEX removal, nitrate utilization, and nitrite production. Benzene proved recalcitrant throughout all operating trials

  18. Low Band Gap Donor–Acceptor Type Polymers Containing 2,3-Bis(4-(decyloxyphenylpyrido[4,3-b]pyrazine as Acceptor and Different Thiophene Derivatives as Donors

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2016-10-01

    Full Text Available Four donor–acceptor type conducting polymers, namely poly(2,3-bis(4-decyloxyphenyl-5,8-bis(4-thiophen-2-ylpyrido[4,3-b]pyrazine (P1, poly(2,3-bis(4-decyloxyphenyl-5,8-bis(4-butylthiophen-2-ylpyrido[4,3-b]pyrazine (P2, poly(2,3-bis(4-(decyloxyphenyl-5,8-bis(4-hexyloxythiophen-2-ylpyrido[4,3-b]pyrazine (P3 and poly(2,3-bis(4-(decyloxyphenyl-5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-ylpyrido[4,3-b]pyrazine (P4, containing thiophene or its derivative as the donor and pyrido[4,3-b]pyrazine as the acceptor were prepared and characterized by cyclic voltammetry, scanning electron microscopy, and UV-Vis spectroscopy to detect the influence of the donor units’ strength on the electrochromic performances. The results demonstrated that all of the polymers could be reversibly reduced and oxidized by p-type doping and n-type doping, and showed near-infrared activities and different color changes in p-type doping process. Especially, P3 and P4 showed lower optical band gap than P1 and P2 due to the strong electron-donating hexyloxythiophen group of P3 and ethylenedioxythiophene group of P4. Besides, P3 and P4 displayed the saturated green color at the neutral state and the desirable transparency at the oxidized state. All the polymers displayed desirable optical contrasts, satisfactory coloration efficiency, excellent stability and short switching time, which made the polymers fascinating candidates in the electrochromic device applications.

  19. Electron donating and acid-base properties of cerium oxide and its mixed oxides with alumina

    International Nuclear Information System (INIS)

    Sugunan, S.; Jalaja, J.M.

    1994-01-01

    The electron donating properties of cerium oxide activated at 300, 500 and 800 degC and of its mixed oxides with alumina were examined based on the adsorption of electron acceptors exhibiting different electron affinities. The surface acidity/basicity of the oxides was determined by titrimetry; the H 0,max values are given. The limit of electron transfer from the oxide surface lies within the region of 1.77 and 2.40 eV in terms of the electron affinity of the electron acceptor. Cerium oxide promotes the electron donor nature of alumina while leaving the limit of electron transfer unchanged. 2 tabs., 4 figs., 13 refs

  20. Effects of Be acceptors on the spin polarization of carriers in p-i-n resonant tunneling diodes

    Energy Technology Data Exchange (ETDEWEB)

    Awan, I. T.; Galvão Gobato, Y. [Departamento de Física, Universidade Federal de São Carlos (UFSCAR) 13560-905, São Carlos, SP (Brazil); Galeti, H. V. A. [Departamento de Engenharia Elétrica, Universidade Federal de São Carlos 13560-905, São Carlos, SP (Brazil); Brasil, M. J. S. P. [Institute of Physics Gleb Wataghin, UNICAMP, Campinas (Brazil); Taylor, D.; Henini, M. [School of Physics and Astronomy, Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-08-07

    In this paper, we have investigated the effect of Be acceptors on the electroluminescence and the spin polarization in GaAs/AlAs p-i-n resonant tunneling diodes. The quantum well emission comprise two main lines separated by ∼20 meV attributed to excitonic and Be-related transitions, which intensities show remarkably abrupt variations at critical voltages, particularly at the electron resonant peak where it shows a high-frequency bistability. The circular-polarization degree of the quantum-well electroluminescence also shows strong and abrupt variations at the critical bias voltages and it attains relatively large values (of ∼−75% at 15 T). These effects may be explored to design novel devices for spintronic applications such as a high-frequency spin-oscillators.

  1. Screening of recombinant glycosyltransferases reveals the broad acceptor specificity of stevia UGT-76G1.

    Science.gov (United States)

    Dewitte, Griet; Walmagh, Maarten; Diricks, Margo; Lepak, Alexander; Gutmann, Alexander; Nidetzky, Bernd; Desmet, Tom

    2016-09-10

    UDP-glycosyltransferases (UGTs) are a promising class of biocatalysts that offer a sustainable alternative for chemical glycosylation of natural products. In this study, we aimed to characterize plant-derived UGTs from the GT-1 family with an emphasis on their acceptor promiscuity and their potential application in glycosylation processes. Recombinant expression in E. coli provided sufficient amounts of enzyme for the in-depth characterization of the salicylic acid UGT from Capsella rubella (UGT-SACr) and the stevia UGT from Stevia rebaudiana (UGT-76G1Sr). The latter was found to have a remarkably broad specificity with activities on a wide diversity of structures, from aliphatic and branched alcohols, over small phenolics to larger flavonoids, terpenoids and even higher glycoside compounds. As an example for its industrial potential, the glycosylation of curcumin was thoroughly evaluated. Under optimized conditions, 96% of curcumin was converted within 24h into the corresponding curcumin β-glycosides. In addition, the reaction was performed in a coupled system with sucrose synthase from Glycine max, to enable the cost-efficient (re)generation of UDP-Glc from sucrose as abundant and renewable resource. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. The effect of electron acceptors on biogas production from tannery sludge of a Mexican wastewater plant

    Science.gov (United States)

    Effluents from the leather processing plants generally are discharged into rivers or are used to irrigate farmland. The biogas production from the digestion of sludge produced could be used as alternative sources for energy and power generation. A study was carried out to examine the effects of vari...

  3. Electron acceptor-based regulation of microbial greenhouse gas production from thawing permafrost

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Jones, Eleanor; Yde, Jacob Clement

    Permafrost contains about 35% of the global soil organic carbon (0-3 m depth). As a consequence of global warming, the active layer thickness is steadily increasing and its organic carbon is becoming available for degradation, causing a concomitant release of CO2 and CH4. The climate forcing...... of sulfate and iron and the microbial community structure regulate the production of CO2 and CH4 in thawing permafrost, and to elucidate how the rate of the organic carbon degradation changes with depth in permafrost-affected soils. This study improves our understanding of climate feedback mechanisms...

  4. Electron-donor-acceptor fullerene derivative retained on electrods using SC3 hydrophobin

    Czech Academy of Sciences Publication Activity Database

    Corvis, Y.; Trzcinska, K.; Rink, R.; Bílková, Petra; Gorecka, E.; Bilewicz, R.; Rogalska, E.

    2007-01-01

    Roč. 111, č. 3 (2007), s. 1176-1179 ISSN 1932-7447 Grant - others:Research Training Network(XE) HPRN-CT-2002-00171; French-Polish bilateral project Polonium(XE) 09184SC Institutional research plan: CEZ:AV0Z10100520 Keywords : fullerene * photovoltaic device * immobilization * cyclic voltammetry * electrochemistry Subject RIV: BM - Solid Matter Physics ; Magnetism

  5. Quinones as electron acceptors and redox mediators for the anaerobic biotransformation of priority pollutants

    NARCIS (Netherlands)

    Cervantes-Carrillo, F.J.

    2002-01-01

    Humus is the most abundant organic fraction in the biosphere. It is composed of a complex structure in which recalcitrant polymers prevail with a residence time lasting decades or even centuries. Despite the recalcitrance of humic substances, they have recently been recognized to play an important

  6. Alternative photosynthetic electron transport pathways during anaerobiosis in the green alga Chlamydomonas reinhardtii.

    Science.gov (United States)

    Hemschemeier, Anja; Happe, Thomas

    2011-08-01

    Oxygenic photosynthesis uses light as energy source to generate an oxidant powerful enough to oxidize water into oxygen, electrons and protons. Upon linear electron transport, electrons extracted from water are used to reduce NADP(+) to NADPH. The oxygen molecule has been integrated into the cellular metabolism, both as the most efficient electron acceptor during respiratory electron transport and as oxidant and/or "substrate" in a number of biosynthetic pathways. Though photosynthesis of higher plants, algae and cyanobacteria produces oxygen, there are conditions under which this type of photosynthesis operates under hypoxic or anaerobic conditions. In the unicellular green alga Chlamydomonas reinhardtii, this condition is induced by sulfur deficiency, and it results in the production of molecular hydrogen. Research on this biotechnologically relevant phenomenon has contributed largely to new insights into additional pathways of photosynthetic electron transport, which extend the former concept of linear electron flow by far. This review summarizes the recent knowledge about various electron sources and sinks of oxygenic photosynthesis besides water and NADP(+) in the context of their contribution to hydrogen photoproduction by C. reinhardtii. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Adsorption of sulfonamides to demineralized pine wood biochars prepared under different thermochemical conditions

    International Nuclear Information System (INIS)

    Xie, Mengxing; Chen, Wei; Xu, Zhaoyi; Zheng, Shourong; Zhu, Dongqiang

    2014-01-01

    The main objective of this study was to understand the key factors and mechanisms controlling adsorption of sulfonamides to biochars. Batch adsorption experiments were performed for sulfamethoxazole and sulfapyridine to three pine-wood biochars prepared under different thermochemical conditions: pyrolysis at 400 °C (C400) and 500 °C (C500), and pyrolysis at 500 °C followed with hydrogenation (C500-H). For both sulfonamides, the adsorbent surface area-normalized adsorption was stronger to C500 than to C400. This is attributable to the enhanced π–π electron-donor–acceptor interaction with the carbon surface of C500 due to the higher degree of graphitization. Despite the relatively large difference in surface O-functionality content between C500 (12.2%) and C500-H (6.6%), the two biochars exhibited nearly identical adsorbent surface area-normalized adsorption, indicating negligible role of surface O-functionalities in the adsorption to these adsorbents. Effects of solution chemistry conditions (pH, Cu 2+ , and dissolved soil humic acid) on adsorption were examined. -- Highlights: • Adsorption to biochars is dominated by π–π electron-donor–acceptor (EDA) interaction. • Graphitic surfaces of biochars are predominant adsorption sites. • Surface O-functionalities of biochars play minor roles in adsorption. • Adsorption affinities are markedly affected by Cu ions and humic acids. -- Adsorption of sulfonamides to biochars is dominated by π–π electron-donor–acceptor (EDA) interaction with the graphitic surface

  8. 78 FR 68985 - Special Conditions: Boeing Model 777-200, -300, and -300ER Series Airplanes; Aircraft Electronic...

    Science.gov (United States)

    2013-11-18

    ... computer network system, and a network extension device. The network extension device will improve domain... Series Airplanes; Aircraft Electronic System Security Protection From Unauthorized Internal Access AGENCY... and connectivity of the passenger service computer network systems to the airplane critical systems...

  9. 77 FR 57039 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Electronic Flight Control System...

    Science.gov (United States)

    2012-09-17

    ... adequacy under Sec. 611 of Public Law 92-574, the ``Noise Control Act of 1972.'' The FAA issues special... Flight Control System: Control Surface Awareness and Mode Annunciation AGENCY: Federal Aviation... feature(s) associated with the control surface awareness and mode annunciation of the electronic flight...

  10. Decay time shortening of fluorescence from donor-acceptor pair proteins using ultrafast time-resolved fluorescence resonance energy transfer spectroscopy

    International Nuclear Information System (INIS)

    Baba, Motoyoshi; Suzuki, Masayuki; Ganeev, Rashid A.; Kuroda, Hiroto; Ozaki, Tsuneyuki; Hamakubo, Takao; Masuda, Kazuyuki; Hayashi, Masahiro; Sakihama, Toshiko; Kodama, Tatsuhiko; Kozasa, Tohru

    2007-01-01

    We improved an ultrafast time-resolved fluorescence resonance energy transfer (FRET) spectroscopy system and measured directly the decrease in the fluorescence decay time of the FRET signal, without any entanglement of components in the picosecond time scale from the donor-acceptor protein pairs (such as cameleon protein for calcium ion indicator, and ligand-activated GRIN-Go proteins pair). The drastic decrease in lifetime of the donor protein fluorescence under the FRET condition (e.g. a 47.8% decrease for a GRIN-Go protein pair) proves the deformation dynamics between donor and acceptor fluorescent proteins in an activated state of a mixed donor-acceptor protein pair. This study is the first clear evidence of physical contact of the GRIN-Go proteins pair using time-resolved FRET system. G protein-coupled receptors (GPCRs) are the most important protein family for the recognition of many chemical substances at the cell surface. They are the targets of many drugs. Simultaneously, we were able to observe the time-resolved spectra of luminous proteins at the initial stage under the FRET condition, within 10 ns from excitation. This new FRET system allows us to trace the dynamics of the interaction between proteins at the ligand-induced activated state, molecular structure change and combination or dissociation. It will be a key technology for the development of protein chip technology

  11. Design, Synthesis, Structural and Spectroscopic Studies of Push-Pull Two-Photon Absorbing Chromophores with Acceptor Groups of Varying Strength

    Science.gov (United States)

    Morales, Alma R.; Frazer, Andrew; Woodward, Adam W.; Ahn-White, Hyo-Yang; Fonari, Alexandr; Tongwa, Paul; Timofeeva, Tatiana; Belfield, Kevin D.

    2013-01-01

    A new series of unsymmetrical diphenylaminofluorene-based chromophores with various strong π-electron acceptors were synthesized and fully characterized. The systematic alteration of the structural design facilitated the investigation of effects such as molecular symmetry and strength of electron-donating and/or withdrawing termini have on optical nonlinearity. In order to determine the electronic and geometrical properties of the novel compounds, a thorough investigation was carried out by a combination of linear and nonlinear spectroscopic techniques, single crystal X-ray diffraction, and quantum chemical calculations. Finally, on the basis of two-photon absorption (2PA) cross sections, the general trend for π -electron accepting ability, i.e., ability to accept charge transfer from diphenylamine was: 2-pyran-4-ylidene malononitrile (pyranone) > dicyanovinyl > bis(dicyanomethylidene)indane > 1-(thiophen-2-yl)propenone > dicyanoethylenyl > 3-(thiophen-2-yl)propenone. An analog with the 2-pyran-4-ylidene malononitrile acceptor group exhibited a nearly three-fold enhancement of the 2PA< δ (1650 GM at 840 nm), relative to other members of the series. PMID:23305555

  12. Ternary Nonfullerene Polymer Solar Cells with 12.16% Efficiency by Introducing One Acceptor with Cascading Energy Level and Complementary Absorption.

    Science.gov (United States)

    Jiang, Weigang; Yu, Runnan; Liu, Zhiyang; Peng, Ruixiang; Mi, Dongbo; Hong, Ling; Wei, Qiang; Hou, Jianhui; Kuang, Yongbo; Ge, Ziyi

    2018-01-01

    A novel small-molecule acceptor, (2,2'-((5E,5'E)-5,5'-((5,5'-(4,4,9,9-tetrakis(5-hexylthiophen-2-yl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(4-(2-ethylhexyl)thiophene-5,2-diyl))bis(methanylylidene)) bis(3-hexyl-4-oxothiazolidine-5,2-diylidene))dimalononitrile (ITCN), end-capped with electron-deficient 2-(3-hexyl-4-oxothiazolidin-2-ylidene)malononitrile groups, is designed, synthesized, and used as the third component in fullerene-free ternary polymer solar cells (PSCs). The cascaded energy-level structure enabled by the newly designed acceptor is beneficial to the carrier transport and separation. Meanwhile, the three materials show a complementary absorption in the visible region, resulting in efficient light harvesting. Hence, the PBDB-T:ITCN:IT-M ternary PSCs possess a high short-circuit current density (J sc ) under an optimal weight ratio of donors and acceptors. Moreover, the open-circuit voltage (V oc ) of the ternary PSCs is enhanced with an increase of the third acceptor ITCN content, which is attributed to the higher lowest unoccupied molecular orbital energy level of ITCN than that of IT-M, thus exhibits a higher V oc in PBDB-T:ITCN binary system. Ultimately, the ternary PSCs achieve a power conversion efficiency of 12.16%, which is higher than the PBDB-T:ITM-based PSCs (10.89%) and PBDB-T:ITCN-based ones (2.21%). This work provides an effective strategy to improve the photovoltaic performance of PSCs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Influence analysis of electronically and vibrationally excited particles on the ignition of methane and hydrogen under the conditions of a gas turbine engine

    Science.gov (United States)

    Deminskii, M. A.; Konina, K. M.; Potapkin, B. V.

    2018-03-01

    The vibronic and electronic energy relaxation phenomena in the specific conditions of a gas turbine engine were investigated in this paper. The plasma-chemical mechanism has been augmented with the results of recent investigations of the processes that involve electronically and vibrationally excited species. The updated mechanism was employed for the computer simulation of plasma-assisted combustion of hydrogen-air and methane-air mixtures under high pressure and in the range of initial temperatures T  =  500-900 K. The updated mechanism was verified using the experimental data. The influence of electronically excited nitrogen on the ignition delay time was analyzed. The rate coefficient of the vibration-vibration exchange between N2 and HO2 was calculated as well as the rate coefficient of HO2 decomposition.

  14. Respiratory electron transfer in Escherichia coli : components, energetics and regulation

    NARCIS (Netherlands)

    Bekker, M.

    2009-01-01

    The respiratory chain that is housed in the bacterial cytoplasmic membrane, generally transfers electrons from NADH to oxygen; in the absence of oxygen it can use several alternative electron acceptors, such as nitrate and fumarate. Transfer of electrons through this chain is usually coupled to the

  15. Exocellular electron transfer in anaerobic microbial communities.

    Science.gov (United States)

    Stams, Alfons J M; de Bok, Frank A M; Plugge, Caroline M; van Eekert, Miriam H A; Dolfing, Jan; Schraa, Gosse

    2006-03-01

    Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory syntrophic consortia of proton-reducing acetogenic bacteria and hydrogen-consuming methanogenic archaea. Anaerobic microorganisms that use insoluble electron acceptors for growth, such as iron- and manganese-oxide as well as inert graphite electrodes in microbial fuel cells, also transfer electrons exocellularly. Soluble compounds, like humic substances, quinones, phenazines and riboflavin, can function as exocellular electron mediators enhancing this type of anaerobic respiration. However, direct electron transfer by cell-cell contact is important as well. This review addresses the mechanisms of exocellular electron transfer in anaerobic microbial communities. There are fundamental differences but also similarities between electron transfer to another microorganism or to an insoluble electron acceptor. The physical separation of the electron donor and electron acceptor metabolism allows energy conservation in compounds as methane and hydrogen or as electricity. Furthermore, this separation is essential in the donation or acceptance of electrons in some environmental technological processes, e.g. soil remediation, wastewater purification and corrosion.

  16. Thermodynamic properties of donor-acceptor complexes of tertiary amine with aryl ketones in hexane medium

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R. [Department of Physics, The New College, Chennai 600 014 (India); Jayakumar, S. [Department of Physics, R.K.M. Vivekananda College, Chennai 600 004 (India); Kannappan, V., E-mail: vkannappan@hotmail.com [Department of Chemistry, Presidency College, Chennai 600 005 (India)

    2012-05-20

    Highlights: Black-Right-Pointing-Pointer Ultrasonic scan is carried out on ternary systems of aromatic tertiary amine and three aryl ketones. Black-Right-Pointing-Pointer Formation of CT complexes is found between tertiary amine with aryl ketones. Black-Right-Pointing-Pointer Stability constant values are computed by ultrasonic and spectral methods are compared. Black-Right-Pointing-Pointer The trend in the 'K' suggests that substituents in ketones influence the stabilities of these complexes. Black-Right-Pointing-Pointer The thermodynamic parameters suggest CT interaction is exothermic and the complexes are thermodynamically stable. - The thermodynamic stability of complexes formed between N,N-dimethylaniline (DMANI) and three ketones, namely, acetophenone (ACP), 4-chloroactophenone (ClACP) and 4-methylacetophenone (MACP) in n-hexane is extensively investigated by spectral and ultrasonic methods. The ultrasound scan was carried out in the temperature range 208.15-313.15 K and at atmospheric pressure on solutions containing equimolar concentrations of components ranging from 0.025 to 0.2 M. The existence of solute-solute interactions has also been confirmed through electronic absorption spectra analyzed with Benesi-Hildebrand theory at 303.15 K. The stability constants of the donor-acceptor complexes determined both by spectroscopic and ultrasonic methods are comparable and follow similar trends. The trend in the formation constants is discussed with structures of the components. The thermodynamic behavior of the systems was explained through the computed values of the free energy ({Delta}G), enthalpy ({Delta}H) and entropy ({Delta}S) changes for complex formation are computed and discussed.

  17. Thermodynamic properties of donor–acceptor complexes of tertiary amine with aryl ketones in hexane medium

    International Nuclear Information System (INIS)

    Kumar, R.; Jayakumar, S.; Kannappan, V.

    2012-01-01

    Highlights: ► Ultrasonic scan is carried out on ternary systems of aromatic tertiary amine and three aryl ketones. ► Formation of CT complexes is found between tertiary amine with aryl ketones. ► Stability constant values are computed by ultrasonic and spectral methods are compared. ► The trend in the ‘K’ suggests that substituents in ketones influence the stabilities of these complexes. ► The thermodynamic parameters suggest CT interaction is exothermic and the complexes are thermodynamically stable. - The thermodynamic stability of complexes formed between N,N-dimethylaniline (DMANI) and three ketones, namely, acetophenone (ACP), 4-chloroactophenone (ClACP) and 4-methylacetophenone (MACP) in n-hexane is extensively investigated by spectral and ultrasonic methods. The ultrasound scan was carried out in the temperature range 208.15–313.15 K and at atmospheric pressure on solutions containing equimolar concentrations of components ranging from 0.025 to 0.2 M. The existence of solute–solute interactions has also been confirmed through electronic absorption spectra analyzed with Benesi-Hildebrand theory at 303.15 K. The stability constants of the donor–acceptor complexes determined both by spectroscopic and ultrasonic methods are comparable and follow similar trends. The trend in the formation constants is discussed with structures of the components. The thermodynamic behavior of the systems was explained through the computed values of the free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) changes for complex formation are computed and discussed.

  18. Water without windows: Evaluating the performance of open cell transmission electron microscopy under saturated water vapor conditions, and assessing its potential for microscopy of hydrated biological specimens.

    Science.gov (United States)

    Cassidy, Cathal; Yamashita, Masao; Cheung, Martin; Kalale, Chola; Adaniya, Hidehito; Kuwahara, Ryusuke; Shintake, Tsumoru

    2017-01-01

    We have performed open cell transmission electron microscopy experiments through pure water vapor in the saturation pressure regime (>0.6 kPa), in a modern microscope capable of sub-Å resolution. We have systematically studied achievable pressure levels, stability and gas purity, effective thickness of the water vapor column and associated electron scattering processes, and the effect of gas pressure on electron optical resolution and image contrast. For example, for 1.3 kPa pure water vapor and 300kV electrons, we report pressure stability of ± 20 Pa over tens of minutes, effective thickness of 0.57 inelastic mean free paths, lattice resolution of 0.14 nm on a reference Au specimen, and no significant degradation in contrast or stability of a biological specimen (M13 virus, with 6 nm body diameter). We have also done some brief experiments to confirm feasibility of loading specimens into an in situ water vapor ambient without exposure to intermediate desiccating conditions. Finally, we have also checked if water experiments had any discernible impact on the microscope performance, and report pertinent vacuum and electron optical data, for reference purposes.

  19. Measurements of ionization cross-section for electron energy-loss microanalysis under well defined scattering conditions

    International Nuclear Information System (INIS)

    Krishnan, K.M.; Echer, C.J.

    1991-04-01

    Partial cross-sections required for electron energy-loss microanalysis have been measured for a series of high purity single crystal standards. For each sample four different scattering geometries were used. The experimental data were compared with theoretical calculations using both standard hydrogenic model and parametrized Hartree-Slater cross-sections. Best agreement between theory and experiment were observed for experiments performed in diffraction mode (image coupling) with the probe convergence angle (0. 84 mrad) much smaller than the spectrometer collection angle (6.84 mrad). In addition, specimen thicknesses from the region of microanalysis were measured by convergent beam electron diffraction. Absolute cross-section based on these measurements are also currently being determined. 10 refs., 2 figs

  20. 78 FR 70848 - Special Conditions: Boeing Model 777-200, -300, and -300ER Series Airplanes; Aircraft Electronic...

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    2013-11-27

    ... unintentional corruption of data and systems critical to the safety and maintenance of the airplane. The... comment are unnecessary, and good cause exists for adopting these special conditions upon publication in...

  1. 78 FR 70849 - Special Conditions: Boeing Model 777-200, -300, and -300ER Series Airplanes; Aircraft Electronic...

    Science.gov (United States)

    2013-11-27

    ... unintentional corruption of data and systems critical to the safety and maintenance of the airplane. The... comment are unnecessary, and good cause exists for adopting these special conditions upon publication in...

  2. 78 FR 68986 - Special Conditions: Boeing Model 777-200, -300, and -300ER Series Airplanes; Aircraft Electronic...

    Science.gov (United States)

    2013-11-18

    ... vulnerabilities from intentional or unintentional corruption of data and systems critical to the safety and... comment are unnecessary, and good cause exists for adopting these special conditions upon publication in...

  3. Spectroscopic investigation of new fullerene based acceptors for organic solar cells; Spektroskopische Untersuchung neuartiger Fullerenakzeptoren fuer organische Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Liedte, Moritz Nils

    2012-04-27

    The main topic of my thesis was the optical spectroscopy of accepters for organic bulk-heterojunction polymer-fullerene solar cells in the visible till near-infrared regime. Pure fullerene samples as well as blends of fullerenes with polymers were studied. Additionally measurements regarding the morphology, spin states and solar cell performance were done. The aims were to determine the ability of new molecules as acceptors for organic solar cells, to find and understand the photoinduced absorption signatures of optical excited anions on fullerene bulks of different sizes and finally to learn about the charge carrier generation process in polymer:Lu{sub 3}N rate at C{sub 80} blends and thus understand the origin of the comparable low current density in this devices, about 25 % less than for P3HT:PC{sub 61}BM solar cells. In our publications due to these topics we presented that the novel C{sub 70}-C{sub 70} dimer fullerenes are fine acceptors for polymer:fullerene solar cells, showing a better absorption coefficient around 500 nm than C{sub 60} based acceptors and high singlet-exciton quenching rates. Anion signatures for fullerene molecules of different sizes were clearly found for C{sub 60{sup -}} at 1.18 eV and for C{sub 70{sup -}} at 0.92 eV. Less clear are my findings regarding the signatures for C{sub 80{sup -}} and C{sub 84{sup -}}. Due to the low signal-to-noise ratio in these measurements and some unique properties of the available materials I was only able to indicate a range from 0.7 eV down to 0.4 eV for the optically detected anion signatures of these fullerenes. Still all fullerenes showed a red shift to lower energies for the anion signatures getting stronger the more carbon atoms the fullerenes were made of. The most detailed research in this thesis was done about the Lu{sub 3}N rate at C{sub 80} molecules application as electron acceptor in P3HT:Lu{sub 3}N rate at C{sub 80} solar cells. The use of this acceptor in combination with P3HT lead to a

  4. Crystal Structure and Band-Gap Engineering of a Semiconducting Coordination Polymer Consisting of Copper(I) Bromide and a Bridging Acceptor Ligand.

    Science.gov (United States)

    Okubo, Takashi; Himoto, Kento; Tanishima, Koki; Fukuda, Sanshiro; Noda, Yusuke; Nakayama, Masanobu; Sugimoto, Kunihisa; Maekawa, Masahiko; Kuroda-Sowa, Takayoshi

    2018-03-05

    A new semiconducting 3D coordination polymer, [Cu 2 Br 2 (ttz)] n (1), with an acceptor bridging ligand, 1,2,4,5-tetrazine (ttz), was synthesized. The complex shows large absorption bands extending to the near-IR region, indicating a small band gap in the coordination polymer. This complex shows higher conductivity than those of [CuBr(pyz)] n (2), including pyrazine (pyz) with a higher lowest unoccupied molecular orbital level. We performed density functional theory band calculations using the VASP program to understand the electronic states and conducting paths of the coordination polymer.

  5. The calculation of water fogging system for process conditioning the flue gas processor by electron beam machine

    International Nuclear Information System (INIS)

    Sanda; Utaya; Suryanto; Kristiyanti

    2008-01-01

    In the course of gas processing flue gas needed water fogging technique to get condition moisture the desired that is from 7% becoming 12% with temperature processed at about 65°C. In this calculation will condition flue gas SO 2 and NO x with debit 20.000 Nm 3 /hour at temperature 135°C. The result to reach the condition have to be sprayed by item of aqueous vapour have diameter 1 mm, so that yielded a speed item of aqueous vapour 776,82 cm/seconds, sum up secretory aqueous vapour from nozzle 0,137.10 -6 kgm/m 2 second, wide of surface nozzle 2,93 mm 2 , diameter and high of vessel 1,13 m and 7,26 m, evaporation time item of aqueous vapour 3,8 seconds and pressure difference in spray cooler vessel equal to 0,3864 bar. (author)

  6. Reducing the efficiency–stability–cost gap of organic photovoltaics with highly efficient and stable small molecule acceptor ternary solar cells

    KAUST Repository

    Baran, Derya

    2016-11-21

    Technological deployment of organic photovoltaic modules requires improvements in device light-conversion efficiency and stability while keeping material costs low. Here we demonstrate highly efficient and stable solar cells using a ternary approach, wherein two non-fullerene acceptors are combined with both a scalable and affordable donor polymer, poly(3-hexylthiophene) (P3HT), and a high-efficiency, low-bandgap polymer in a single-layer bulk-heterojunction device. The addition of a strongly absorbing small molecule acceptor into a P3HT-based non-fullerene blend increases the device efficiency up to 7.7 ± 0.1% without any solvent additives. The improvement is assigned to changes in microstructure that reduce charge recombination and increase the photovoltage, and to improved light harvesting across the visible region. The stability of P3HT-based devices in ambient conditions is also significantly improved relative to polymer:fullerene devices. Combined with a low-bandgap donor polymer (PBDTTT-EFT, also known as PCE10), the two mixed acceptors also lead to solar cells with 11.0 ± 0.4% efficiency and a high open-circuit voltage of 1.03 ± 0.01 V.

  7. Limitations and design considerations for donor-acceptor systems in luminescent solar concentrators: the effect of coupling-induced red-edge absorption

    Science.gov (United States)

    MacQueen, Rowan W.; Tayebjee, Murad J. Y.; Webb, James E. A.; Falber, Alexander; Thordarson, Pall; Schmidt, Timothy W.

    2016-06-01

    Luminescent solar concentrators (LSCs) use luminescence and waveguiding to concentrate photons within thin dielectric slabs for use in photovoltaic, lighting, and photobioreactor applications. Donor-acceptor systems of organic chromophores are widely used in LSCs to broaden the sunlight absorption range and attempt to reduce loss-inducing reabsorption by the emitting chromophore. We use raytrace simulations across a large parameter space to model the performance of LSCs containing two novel donor-acceptor trimers based on the perylene moiety. We find that under certain conditions, trimers outperform single-dye LSCs as expected. However, at higher concentrations, a slight increase in red-edge absorption by the trimers increases reabsorption and has a deleterious effect on LSC performance. This underscores the large effect that even small changes in the red edge can have, and may discourage the use of donor-acceptor schemes with high interchromophore coupling that promotes red-edge absorption. Finally, we show that for a LSC-PV pair, selecting a PV cell that is well-matched with the LSC emission spectrum has a large effect on the flux gain of the system, and that the systems studied here are well-matched to emerging PV technologies.

  8. The effects of surface conditions on electronic transportation mechanism of Al/SnO2/p-Si/Al structure

    International Nuclear Information System (INIS)

    Karadeniz, S.

    2001-01-01

    In the present work it was aimed to determine the effect of surface states on the electronic conductivity of Al/SnO 2 /p-Si/Al structure. In order to realize that goal, the Al/SnO 2 /p-Si/Al diodes were prepared p-types, 0.8 Ω-cm resistivity from single crystalline silicon of orientation (111). A spraying system was established in order to produce SnO 2 thin films. The morphology of SnO 2 thin films were measured by means of Atomic Force Microscope (AFM). The physical parameters which effected on the electronical conductivity of the structures were determined. The forward current-voltage (I-V) measurements were performed in the temperature range of 173-313 K. The reverse capacitance-voltage (C-V) characteristics were measured at 100 Hz, 1 kHz,10 kHz, 100 kHz, 500 kHz and 1 MHz frequencies at the same temperature range. The energy profile of the surface states effecting on diodes were determined by using high-low frequency capacitance method, Chattopadhyay method and the relation between surface states and ideality factor

  9. Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors

    Directory of Open Access Journals (Sweden)

    Kenny F. Chou

    2015-06-01

    Full Text Available Förster (or fluorescence resonance energy transfer amongst semiconductor quantum dots (QDs is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting.

  10. The Physics of Small Molecule Acceptors for Efficient and Stable Bulk Heterojunction Solar Cells

    KAUST Repository

    Gasparini, Nicola

    2018-01-29

    Organic bulk heterojunction solar cells based on small molecule acceptors have recently seen a rapid rise in the power conversion efficiency with values exceeding 13%. This impressive achievement has been obtained by simultaneous reduction of voltage and charge recombination losses within this class of materials as compared to fullerene-based solar cells. In this contribution, the authors review the current understanding of the relevant photophysical processes in highly efficient nonfullerene acceptor (NFA) small molecules. Charge generation, recombination, and charge transport is discussed in comparison to fullerene-based composites. Finally, the authors review the superior light and thermal stability of nonfullerene small molecule acceptor based solar cells, and highlight the importance of NFA-based composites that enable devices without early performance loss, thus resembling so-called burn-in free devices.

  11. Rapid Energy Transfer Enabling Control of Emission Polarization in Perylene Bisimide Donor-Acceptor Triads.

    Science.gov (United States)

    Menelaou, Christopher; ter Schiphorst, Jeroen; Kendhale, Amol M; Parkinson, Patrick; Debije, Michael G; Schenning, Albertus P H J; Herz, Laura M

    2015-04-02

    Materials showing rapid intramolecular energy transfer and polarization switching are of interest for both their fundamental photophysics and potential for use in real-world applications. Here, we report two donor-acceptor-donor triad dyes based on perylene-bisimide subunits, with the long axis of the donors arranged either parallel or perpendicular to that of the central acceptor. We observe rapid energy transfer (energy transfer rate for the linearly arranged triad but severely underestimates it for the orthogonal case. We show that the rapid energy transfer arises from a combination of through-bond coupling and through-space transfer between donor and acceptor units. As they allow energy cascading to an excited state with controllable polarization, these triad dyes show high potential for use in luminescent solar concentrator devices.

  12. Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors

    Science.gov (United States)

    Chou, Kenny F.; Dennis, Allison M.

    2015-01-01

    Förster (or fluorescence) resonance energy transfer amongst semiconductor quantum dots (QDs) is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting. PMID:26057041

  13. Rotaxanes and Photovoltaic Materials Based on Pi-Conjugated Donors and Acceptors: Toward Energy Transduction on the Nanoscale

    Science.gov (United States)

    Bruns, Carson J.

    The flow of energy between its various forms is central to our understanding of virtually all natural phenomena, from the origins and fate of the universe to the mechanisms that underpin Life. Therefore, a deeper fundamental understanding of how to manage energy processes at the molecular scale will open new doors in science and technology. This dissertation describes organic molecules and materials that are capable of transducing various forms of energy on the nanoscale, namely, a class of mechanically interlocked molecules known as rotaxanes for electrochemical-to-mechanical energy transduction (Part I), and a class of thin films known as organic photovoltaics (OPVs) for solar-to-electric energy transduction (Part II). These materials are all based on conjugated molecules with a capacity to donate or accept pi-electrons. A contemporary challenge in molecular nanotechnology is the development of artificial molecular machines (AMMs) that mimic the ability of motor proteins (e.g. myosin, kinesin) to perform mechanical work by leveraging a combination of energy sources and rich structural chemistry. Part I describes the synthesis, characterization, molecular dynamics, and switching properties of a series of `daisy chain' and oligorotaxane AMM prototypes. All compounds are templated by charge transfer and hydrogen bonding interactions between pi-associated 1,5-dioxynaphthlene donors appended with polyether groups and pi-acceptors of either neutral (naphthalenediimide) or charged (4,4´-bipyridinium) varieties, and are synthesized using efficient one-pot copper(I)-catalyzed azide-alkyne cycloaddition `click chemistry' protocols. The interlocked architectures of these rotaxanes enable them to express sophisticated secondary structures (i.e. foldamers) and mechanical motions in solution, which have been elucidated using dynamic 1H NMR spectroscopy. Furthermore, molecular dynamics simulations, cyclic voltammetry, and spectroelectrochemistry experiments have demonstrated

  14. Generalized boundary conditions in an existence and uniqueness proof for the solution of the non-stationary electron Boltzmann equation by means of operator-semigroups

    International Nuclear Information System (INIS)

    Bartolomaeus, G.; Wilhelm, J.

    1983-01-01

    Recently, based on the semigroup approach a new proof was presented of the existence of a unique solution of the non-stationary Boltzmann equation for the electron component of a collision dominated plasma. The proof underlies some restriction which should be overcome to extend the validity range to other problems of physical interest. One of the restrictions is the boundary condition applied. The choice of the boundary condition is essential for the proof because it determines the range of definition of the infinitesimal generator and thus the operator semigroup itself. The paper proves the existence of a unique solution for generalized boundary conditions, this solution takes non-negative values, which is necessary for a distribution function from the physical point of view. (author)

  15. Quantifying the impact of chronic conditions on a diagnosis of major depressive disorder in adults: a cohort study using linked electronic medical records.

    Science.gov (United States)

    Ryu, Euijung; Chamberlain, Alanna M; Pendegraft, Richard S; Petterson, Tanya M; Bobo, William V; Pathak, Jyotishman

    2016-04-26

    Major depressive disorder (MDD) is often comorbid with other chronic mental and physical health conditions. Although the literature widely acknowledges the association of many chronic conditions with the risk of MDD, the relative importance of these conditions on MDD risk in the presence of other conditions is not well investigated. In this study, we aimed to quantify the relative contribution of selected chronic conditions to identify the conditions most influential to MDD risk in adults and identify differences by age. This study used electronic health record (EHR) data on patients empanelled with primary care at Mayo Clinic in June 2013. A validated EHR-based algorithm was applied to identify newly diagnosed MDD patients between 2000 and 2013. Non-MDD controls were matched 1:1 to MDD cases on birth year (±2 years), sex, and outpatient clinic visits in the same year of MDD case diagnosis. Twenty-four chronic conditions defined by Chronic Conditions Data Warehouse were ascertained in both cases and controls using diagnosis codes within 5 years of index dates (diagnosis dates for cases, and the first clinic visit dates for matched controls). For each age group (45 years or younger, between 46 and 60, and over 60 years), conditional logistic regression models were used to test the association between each condition and subsequent MDD risk, adjusting for educational attainment and obesity. The relative influence of these conditions on the risk of MDD was quantified using gradient boosting machine models. A total of 11,375 incident MDD cases were identified between 2000 and 2013. Most chronic conditions (except for eye conditions) were associated with risk of MDD, with different association patterns observed depending on age. Among 24 chronic conditions, the greatest relative contribution was observed for diabetes mellitus for subjects aged ≤ 60 years and rheumatoid arthritis/osteoarthritis for those over 60 years. Our results suggest that specific chronic

  16. 77 FR 75071 - Special Conditions: Embraer S.A., Model EMB-550 Airplanes; Electrical/Electronic Equipment Bay...

    Science.gov (United States)

    2012-12-19

    ... takeoff. The primary flight controls consist of hydraulically powered fly-by-wire elevators, aileron and... FAA must issue a finding of regulatory adequacy under Sec. 611 of Public Law 92-574, the ``Noise Control Act of 1972.'' The FAA issues special conditions, as defined in 14 CFR 11.19, in accordance with...

  17. 78 FR 11560 - Special Conditions: Embraer S.A., Model EMB-550 Airplane; Electronic Flight Control System...

    Science.gov (United States)

    2013-02-19

    ... exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36... ``Noise Control Act of 1972.'' The FAA issues special conditions, as defined in 14 CFR part 11.19, in... low energy cues are not a nuisance in all take-off and landing altitude ranges for which certification...

  18. Differences in gene expression of human xylosyltransferases and determination of acceptor specificities for various proteoglycans

    Energy Technology Data Exchange (ETDEWEB)

    Roch, Christina; Kuhn, Joachim; Kleesiek, Knut [Institut fuer Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum NRW, Universitaetsklinik der Ruhr-Universitaet Bochum, 32545 Bad Oeynhausen (Germany); Goetting, Christian, E-mail: cgoetting@hdz-nrw.de [Institut fuer Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum NRW, Universitaetsklinik der Ruhr-Universitaet Bochum, 32545 Bad Oeynhausen (Germany)

    2010-01-01

    The xylosyltransferase (XT) isoforms XT-I and XT-II initiate the posttranslational glycosaminoglycan (GAG) synthesis. Here, we determined the relative expression of both isoforms in 33 human cell lines. The majority of tested cell lines showed dominant XYLT2 gene expression, while only in 23132/87, JAR, NCI-H510A and THP-1 was the XT-I mRNA expression higher. Nearly equal expression levels were detected in six cell lines. Additionally, to shed light on putative differences in acceptor specificities the acceptor properties of potential acceptor sequences were determined. Peptides were expressed as glutathione-S-transferase fusion proteins containing putative or known GAG attachment sites of in vivo proteoglycans. Kinetic analysis showed that K{sub m} and V{sub max} values for XT-I mediated xylosylation were slightly higher than those for XT-II, and that XT-I showed a lesser stringency concerning the acceptor sequence. Mutagenesis of the bikunin peptide sequence in the G-S-G attachment site and flanking regions generated potential acceptor molecules. Here, mutations on the N-terminal side and the attachment site were found to be more susceptible to a loss of acceptor function than mutations in the C-terminus. Altogether the known consensus sequence a-a-a-a-G-S-G-a-a/G-a ('a' representing Asp or Glu) for XT-I mediated xylosylation could be approved and additionally extended to apply to XT-II as well.

  19. “Terms and conditions of use” for journal articles and scholarly journals : A survey on the licensing processes associated with electronic scholarly materials

    Science.gov (United States)

    Hidaka, Masako

    Copyright policies and terms directly affect the approach taken by journal editors, authors and readers regarding dealing with of articles and/or copyrighted materials. However Japanese academic society publishers have some trouble in licensing processes for copyrighted materials as previous studies pointed out. In 2011 we conducted a survey on “terms and conditions of use” of electronic journal and the licensing practices associated with electronic scholarly materials. The survey showed commercial publishers have enough announcements on reuse of copyrighted materials for readers. On the other hand Japanese academic societies' cares for readers tend to not enough. They publish journals both in Japanese and in English. Subsequently, English and Japanese templates of “terms and conditions of use” for Japanese academic society publishers were proposed. The templates were developed based on an understanding of the International Association of Scientific, Technical and Medical Publishers' “STM Permissions Guidelines,” which were designed to establish a standard and reasonable approach to granting permission for republication to all signatory publishers.The survey showed that Japanese academic society publishers and commercial publishers are facing the same issues regarding acceptable use of electronic supplemental materials for journal articles. This issue remains to be solved.

  20. Electronic differentiation competes with transition state sensitivity in palladium-catalyzed allylic substitutions

    Directory of Open Access Journals (Sweden)

    Goldfuss Bernd

    2007-10-01

    Full Text Available Abstract Electronic differentiations in Pd-catalyzed allylic substitutions are assessed computationally from transition structure models with electronically modified phospha-benzene-pyridine ligands. Although donor/acceptor substitutions at P and N ligand sites were expected to increase the site selectivity, i.e. the preference for "trans to P" attack at the allylic intermediate, acceptor/acceptor substitution yields the highest selectivity. Energetic and geometrical analyses of transition structures show that the sensitivity for electronic differentiation is crucial for this site selectivity. Early transition structures with acceptor substituted ligands give rise to more intensive Pd-allyl interactions, which transfer electronic P,N differentiation of the ligand more efficiently to the allyl termini and hence yield higher site selectivities.

  1. Biomimetic oxidation of pyrene and related aromatic hydrocarbons. Unexpected electron accepting abilities of pyrenequinones.

    Science.gov (United States)

    López-Moreno, Alejandro; Clemente-Tejeda, David; Calbo, Joaquín; Naeimi, Atena; Bermejo, Francisco A; Ortí, Enrique; Pérez, Emilio M

    2014-08-25

    We present a mild catalytic method to oxidize PAHs and, in particular, pyrene. The pyrenediones are much better electron acceptors than benzoquinone in the gas phase and present similar accepting abilities in solution.

  2. New Type of Donor-Acceptor Through-Space Conjugated Polymer

    OpenAIRE

    Lin Lin; Yasuhiro Morisaki; Yoshiki Chujo

    2010-01-01

    We report the synthesis and properties of a novel through-space conjugated polymer with a [2.2]paracyclophane skeleton. The obtained polymer possessed donor (fluorene) and acceptor (2,1,3-benzothiadiazole) segments that were alternately π-stacked in proximity via the [2.2]paracyclophane moieties. The good overlap between the emission peak of the donor unit (fluorene) and the CT band of the acceptor unit (2,1,3-benzothiadiazole) caused fluorescence resonance energy transfer, and the visible gr...

  3. Synthesis, Characterization, Absorbance, Fluorescence and Non Linear Optical Properties of Some Donor Acceptor Chromophores

    International Nuclear Information System (INIS)

    Asiri, Abdullah M.; Khan, Salman A.; Alamry, Kalid A.; Al-Amoudi, Muhammed S.

    2012-01-01

    Three carbazole chromophores featuring dicyano, cyano, ethyl acetate and dimethyl acetate groups as an acceptor moiety with a π-conjugated spacer and N-methyl dibenzo[b]pyrole as donor were synthesized by Knovenagel condensation and characterized by IR, 1 HNMR, 13 CNMR, UV-vis, fluorescence spectroscopy, electrochemistry and theoretical B3LYP/6-311G* level whilst NLO properties and spectroscopic quantities were calculated. Calculations showed remarkable trend with HOMO located on the donor moiety and LUMO on the acceptors dicyano methylene, cyano, ethyl acetate methylene and dimethyl acetate methylene. In agreement with the calculations, solvatochromic, behavior intramolecular charge transfer band was observed in the visible region

  4. Electrical characterization of acceptor levels in Be-implanted GaN

    OpenAIRE

    Yoshitaka, Nakano; Takashi, Jimbo

    2002-01-01

    We have investigated electrically the acceptor levels that are present in Be-implanted GaN. Slight p-type conductivity was attained in undoped GaN films by Be implantation and subsequent annealing at 1050°C with a SiO2 encapsulation layer. Capacitance-frequency measurements showed a typical dispersion effect characteristic of deep acceptors in fabricated Schottky diodes. Thermal admittance spectroscopy measurements revealed a discrete deep level located at ? 231meV above the valence band. Thi...

  5. Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

    Directory of Open Access Journals (Sweden)

    Thibault E. Schmid

    2015-12-01

    Full Text Available The copper-catalyzed asymmetric conjugate addition (ACA of nucleophiles onto polyenic Michael acceptors represents an attractive and powerful methodology for the synthesis of relevant chiral molecules, as it enables in a straightforward manner the sequential generation of two or more stereogenic centers. In the last decade, various chiral copper-based catalysts were evaluated in combination with different nucleophiles and Michael acceptors, and have unambiguously demonstrated their usefulness in the control of the regio- and enantioselectivity of the addition. The aim of this review is to report recent breakthroughs achieved in this challenging field.

  6. Comparative scanning electron microscope study of the degradation of a plasticized polyvinyl chloride waterproofing membrane in different conditions

    Directory of Open Access Journals (Sweden)

    A. Pedrosa

    2017-01-01

    Full Text Available This paper discusses the analysis of several samples of a plasticized polyvinyl chloride (PVC-P waterproofing membrane. The samples were extracted from different areas of the same flat roof, which was in service for over 12 years. An original sample of an identical PVC-P membrane that was not installed on the roof was also analyzed. The analysis of the materials was carried out using a scanning electron microscope (SEM. An elemental analysis of every sample was also performed by energy dispersive X-ray spectroscopy (EDS. Micrographs and the elemental composition of the samples were compared with the data obtained in the analysis of the original sample. The results show dehydrochlorination of the polymer in two of the samples studied and great deterioration that was not visible to the naked eye in the sample that was totally exposed to the weather.

  7. Comparative scanning electron microscope study of the degradation of a plasticized polyvinyl chloride waterproofing membrane in different conditions

    International Nuclear Information System (INIS)

    Pedrosa, A.; Del Río, M.

    2017-01-01

    This paper discusses the analysis of several samples of a plasticized polyvinyl chloride (PVC-P) waterproofing membrane. The samples were extracted from different areas of the same flat roof, which was in service for over 12 years. An original sample of an identical PVC-P membrane that was not installed on the roof was also analyzed. The analysis of the materials was carried out using a scanning electron microscope (SEM). An elemental analysis of every sample was also performed by energy dispersive X-ray spectroscopy (EDS). Micrographs and the elemental composition of the samples were compared with the data obtained in the analysis of the original sample. The results show dehydrochlorination of the polymer in two of the samples studied and great deterioration that was not visible to the naked eye in the sample that was totally exposed to the weather. [es

  8. On the validity of generalized scattering equations and corresponding inelastic cross-section expressions for comprehensive electron diffraction conditions

    International Nuclear Information System (INIS)

    Allen, L.J.; Josefsson, T. W.

    1996-01-01

    Generalized scattering equations for electron diffraction in a crystalline environment have recently been derived with the assumption that the zeroth order Laue zone (ZOLZ) lies parallel to the crystal surface (or alternatively that the zone-axis is parallel to the crystal surface normal) [L.J. Allen and T. W. Josefsson, Phys. Rev. B 52, 3184 (1995)]. The contribution from higher order Laue zones (HOLZs) was not considered. It is shown that these scattering equations are in fact valid for general orientations of the ZOLZ with respect to the crystal surface, except for the specific case where the ZOLZ lies perpendicular to the surface. Furthermore, a widely applicable expression for the cross section for any type of inelastic scattering in a crystal, is shown to be valid for any orientation of the ZOLZ and allows the inclusion of reflections in the HOLZs. 8 refs., 1 fig

  9. Thieno[3,4-c]Pyrrole-4,6-Dione-Based Polymer Acceptors for High Open-Circuit Voltage All-Polymer Solar Cells

    KAUST Repository

    Liu, Shengjian

    2017-04-20

    While polymer acceptors are promising fullerene alternatives in the fabrication of efficient bulk heterojunction (BHJ) solar cells, the range of efficient material systems relevant to the “all-polymer” BHJ concept remains narrow, and currently limits the perspectives to meet the 10% efficiency threshold in all-polymer solar cells. This report examines two polymer acceptor analogs composed of thieno[3,4-c]pyrrole-4,6-dione (TPD) and 3,4-difluorothiophene ([2F]T) motifs, and their BHJ solar cell performance pattern with a low-bandgap polymer donor commonly used with fullerenes (PBDT-TS1; taken as a model system). In this material set, the introduction of a third electron-deficient motif, namely 2,1,3-benzothiadiazole (BT), is shown to (i) significantly narrow the optical gap (Eopt) of the corresponding polymer (by ≈0.2 eV) and (ii) improve the electron mobility of the polymer by over two orders of magnitude in BHJ solar cells. In turn, the narrow-gap P2TPDBT[2F]T analog (Eopt = 1.7 eV) used as fullerene alternative yields high open-circuit voltages (VOC) of ≈1.0 V, notable short-circuit current values (JSC) of ≈11.0 mA cm−2, and power conversion efficiencies (PCEs) nearing 5% in all-polymer BHJ solar cells. P2TPDBT[2F]T paves the way to a new, promising class of polymer acceptor candidates.

  10. Effects of temperature, packaging and electron beam irradiation processing conditions on the property behaviour of Poly (ether-block-amide) blends

    International Nuclear Information System (INIS)

    Murray, Kieran A.; Kennedy, James E.; McEvoy, Brian; Vrain, Olivier; Ryan, Damien; Cowman, Richard; Higginbotham, Clement L.

    2014-01-01

    The radiation stability of Poly (ether-block-amide) (PEBA) blended with a multifunctional phenolic antioxidant and a hindered amide light stabiliser was examined under various temperatures, packaging and electron beam processing conditions. FTIR revealed that there were slight alterations to the PEBA before irradiation; however, these became more pronounced following irradiation. The effect of varying the temperature, packaging and processing conditions on the resultant PEBA properties was apparent. For example, rheology demonstrated that the structural properties could be enhanced by manipulating the aforementioned criteria. Mechanical testing exhibited less radiation resistance when the PEBA samples were vacuum packed and exposed to irradiation. MFI and AFM confirmed that the melting strength and surface topography could be reduced/increased depending on the conditions employed. From this study it was concluded that virgin PEBA submerged in dry ice with non-vacuum packaging during the irradiation process, provided excellent radiation resistance (20.9% improvement) in contrast to the traditional method. - Highlights: • PEBA was melt blended with Irganox 565 and Tinuvin 783. • All virgin and blended PEBA samples were exposed to electron beam irradiation. • Virgin and blended PEBA was exposed to different temperatures during irradiation. • Non-vacuum and vacuum packed PEBA samples were compared following irradiation. • Virgin PEBA with non-vacuum packaging in dry ice improved the radiation resistance

  11. Improving the performance of solution-processed organic solar cells by incorporating small molecule acceptors into a ternary bulk heterojunction based on DH6T:Mq3:PCBM (M = Ga, Al)

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Fahmi F. [Center for Composites, Institute for Vehicle Systems & Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Soft Materials & Devices Lab, Department of Physics, Faculty of Science & Health, Koya University, Koya, Kurdistan Region (Iraq); Development Center for Research and Training, University of Human Development, Sulaimani, Kurdistan Region (Iraq); Yahya, Mohd Yazid, E-mail: yazidyahya@utm.my [Center for Composites, Institute for Vehicle Systems & Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Sulaiman, Khaulah [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-02-15

    Improvement in the overall performance of solution-processed organic solar cells based on a ternary heterostructure was realized by means of incorporating small molecules of tris(8-hydroxyquinoline) gallium (Gaq3) or Alq3 electron acceptors. The donor host polymer was α,ω-dihexyl-sexithiophene (DH6T), while the ultimate acceptor was fullerene (PC{sub 61}BM). The results showed that short circuit current (I{sub Sc}), open circuit voltage (V{sub oc}), and fill factor (FF) of the devices were pronouncedly enhanced by the inclusion of Gaq3 or Alq3. The maximum output power and conversion efficiency of the ternary devices were increased by an order of 5.8 times compared to that of the control devices. These improvements were ascribed to the broadened light absorption, energy levels alignment between the donor-acceptor components, a balanced charge transfer, and increased crystallinity of the devices active layer. The results were ascertained and analyzed by means of UV–Vis, PL, XRD, IV and TEM investigations. - Highlights: • Ternary solution-processed OSCs including Gaq3 and Alq3 acceptors were realized. • The power and efficiency of the devices were increased by an order of 5.8. • Broadened absorption and improved crystallinity were achieved for the active layers.

  12. Improving the performance of solution-processed organic solar cells by incorporating small molecule acceptors into a ternary bulk heterojunction based on DH6T:Mq3:PCBM (M = Ga, Al)

    International Nuclear Information System (INIS)

    Muhammad, Fahmi F.; Yahya, Mohd Yazid; Sulaiman, Khaulah

    2017-01-01

    Improvement in the overall performance of solution-processed organic solar cells based on a ternary heterostructure was realized by means of incorporating small molecules of tris(8-hydroxyquinoline) gallium (Gaq3) or Alq3 electron acceptors. The donor host polymer was α,ω-dihexyl-sexithiophene (DH6T), while the ultimate acceptor was fullerene (PC 61 BM). The results showed that short circuit current (I Sc ), open circuit voltage (V oc ), and fill factor (FF) of the devices were pronouncedly enhanced by the inclusion of Gaq3 or Alq3. The maximum output power and conversion efficiency of the ternary devices were increased by an order of 5.8 times compared to that of the control devices. These improvements were ascribed to the broadened light absorption, energy levels alignment between the donor-acceptor components, a balanced charge transfer, and increased crystallinity of the devices active layer. The results were ascertained and analyzed by means of UV–Vis, PL, XRD, IV and TEM investigations. - Highlights: • Ternary solution-processed OSCs including Gaq3 and Alq3 acceptors were realized. • The power and efficiency of the devices were increased by an order of 5.8. • Broadened absorption and improved crystallinity were achieved for the active layers.

  13. Doping Phosphorene with Holes and Electrons through Molecular Charge Transfer.

    Science.gov (United States)

    Vishnoi, Pratap; Rajesh, S; Manjunatha, S; Bandyopadhyay, Arkamita; Barua, Manaswee; Pati, Swapan K; Rao, C N R

    2017-11-03

    An important aspect of phosphorene, the novel two-dimensional semiconductor, is whether holes and electrons can both be doped in this material. Some reports found that only electrons can be preferentially doped into phosphorene. There are some theoretical calculations showing charge-transfer interaction with both tetrathiafulvalene (TTF) and tetracyanoethylene (TCNE). We have carried out an investigation of chemical doping of phosphorene by a variety of electron donor and acceptor molecules, employing both experiment and theory, Raman scattering being a crucial aspect of the study. We find that both electron acceptors and donors interact with phosphorene by charge-transfer, with the acceptors having more marked effects. All the three Raman bands of phosphorene soften and exhibit band broadening on interaction with both donor and acceptor molecules. First-principles calculations establish the occurrence of charge-transfer between phosphorene with donors as well as acceptors. The absence of electron-hole asymmetry is noteworthy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Electron/electron acoustic instability

    International Nuclear Information System (INIS)

    Gary, S.P.

    1987-01-01

    The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma

  15. Electronic properties of magnetically doped nanotubes

    Indian Academy of Sciences (India)

    Unknown

    body of publications since their discovery in 1991 (Iijima. 1991). Recent experimental (Lee et al 1997; Rao et al. 1997; Grigorian et al 1998a, b) and theoretical (Miya- moto et al 1995; Esfarjani et al 1999) studies on doping nanotubes focused on doping by alkali metal or halogene elements as electron donors or acceptors, ...

  16. High-performance all-polymer solar cells via side-chain engineering of the polymer acceptor: the importance of the polymer packing structure and the nanoscale blend morphology.

    Science.gov (United States)

    Lee, Changyeon; Kang, Hyunbum; Lee, Wonho; Kim, Taesu; Kim, Ki-Hyun; Woo, Han Young; Wang, Cheng; Kim, Bumjoon J

    2015-04-17

    The effectiveness of side-chain engineering is demonstrated to produce highly efficient all-polymer solar cells (efficiency of 5.96%) using a series of naphthalene diimide-based polymer acceptors with controlled side chains. The dramatic changes in the polymer packing, blend morphology, and electron mobility of all-polymer solar cells elucidate clear trends in the photovoltaic performances. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Characterization of Nucleobase Analogue FRET Acceptor tCnitro

    DEFF Research Database (Denmark)

    Preus, Søren; Börjesson, Karl; Kilså, Kristine

    2010-01-01

    , the UV-vis absorption of tCnitro is monitored in a broad pH range and the neutral form is found to be totally predominant under physiological conditions with a pKa of 11.1. The structure and electronic spectrum of tCnitrois further characterized by density functional theory calculations....

  18. Design and synthesis of bipyridine platinum(II) bisalkynyl fullerene donor-chromophore-acceptor triads with ultrafast charge separation.

    Science.gov (United States)

    Lee, Sai-Ho; Chan, Chris Tsz-Leung; Wong, Keith Man-Chung; Lam, Wai Han; Kwok, Wai-Ming; Yam, Vivian Wing-Wah

    2014-07-16

    Donor-chromophore-acceptor triads, (PTZ)2-Pt(bpy)-C60 and ((t)BuPTZ)2-Pt(bpy)-C60, along with their model compound, (Ph)2-Pt(bpy)-C60, have been synthesized and characterized; their photophysical and electrochemical properties have been studied, and the origin of the absorption and emission properties has been supported by computational studies. The photoinduced electron transfer reactions have been investigated using the femtosecond and nanosecond transient absorption spectroscopy. In dichloromethane, (Ph)2-Pt(bpy)-C60 shows ultrafast triplet-triplet energy transfer from the (3)MLCT/LLCT excited state within 4 ps to give the (3)C60* state, while in (PTZ)2-Pt(bpy)-C60 and ((t)BuPTZ)2-Pt(bpy)-C60, charge-separated state forms within 400 fs from the (3)MLCT/LLCT excited state with efficiency of over 0.90, and the total efficiency with the contribution of (3)C60* is estimated to be 0.99. Although the forward electron transfer reactions are very rapid, the charge-separated state recombines to the singlet ground state at a time of hundreds of nanoseconds because of the difference in spin multiplicity between the charge-separated state and the ground state.

  19. Investigation of the Temperature Dependence of the Acceptor Center Relaxation Rate in Silicon by the mu^-SR-Method

    CERN Document Server

    Mamedov, T N; Stojkov, A V; Andrianov, D G; Gerlach, D; Zimmermann, U; Gorelkin, V N; Kormann, O; Major, J V; Shevchik, M

    2000-01-01

    Results on the temperature dependence of the residual polarization of negative muons in silicon with phosphorus (3.2 cdot 10^12, 2.3 cdot 10^15 and 4.5 cdot 10^18 cm^-3) and aluminium (2 cdot 10^14 and 2.4 cdot 10^18 cm^-3) impurities are presented. The measurements were carried out in a transverse to the direction of the muon spin magnetic field of 2000 Oe in the temperature range 4.2-300 K. The temperature dependence of the relaxation rate of the magnetic moment of the Al shallow acceptor centre in undeformed silicon is determined for the first time. The constant of the hyperfine interaction between the magnetic moment of the muon and that of the electron shell of the muonic atom A_hf/2pi approx 3 cdot 10^7 s^-1) and the coefficient for capture of free electrons by a neutral aluminium atom in silicon (beta (Al^0) approx 7 cdot 10^-14 cm^3 s^-1 at 30 K) are estimated.

  20. Mechanism and Dynamics of Charge Transfer in Donor-Bridge-Acceptor Systems

    NARCIS (Netherlands)

    Gorczak-Vos, N.

    2016-01-01

    Photoinduced charge transfer in organic materials is a fundamental process in various biological and technological areas. Donor-bridge-acceptor (DBA) molecules are used as model systems in numerous theoretical and experimental work to systematically study and unravel the underlying mechanisms of