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Sample records for cinnamon-derived michael acceptor

  1. Hexamethoxylated Monocarbonyl Analogues of Curcumin Cause G2/M Cell Cycle Arrest in NCI-H460 Cells via Michael Acceptor-Dependent Redox Intervention.

    Science.gov (United States)

    Li, Yan; Zhang, Li-Ping; Dai, Fang; Yan, Wen-Jing; Wang, Hai-Bo; Tu, Zhi-Shan; Zhou, Bo

    2015-09-09

    Curcumin, derived from the dietary spice turmeric, holds promise for cancer prevention. This prompts much interest in investigating the action mechanisms of curcumin and its analogues. Two symmetrical hexamethoxy-diarylpentadienones (1 and 2) as cucumin analogues were reported to possess significantly enhanced cytotoxicity compared with the parent molecule. However, the detailed mechanisms remain unclear. In this study, compounds 1 and 2 were identified as the G2/M cell cycle arrest agents to mediate the cytotoxicity toward NCI-H460 cells via Michael acceptor-dependent redox intervention. Compared with curcumin, they could more easily induce a burst of reactive oxygen species (ROS) and collapse of the redox buffering system. One possible reason is that they could more effectively target intracellular TrxR to convert this antioxidant enzyme into a ROS promoter. Additionally, they caused up-regulation of p53 and p21 and down-regulation of redox-sensitive Cdc25C along with cyclin B1/Cdk1 in a Michael acceptor- and ROS-dependent fashion. Interestingly, in comparison with compound 2, compound 1 displayed a relatively weak ability to generate ROS but increased cell cycle arrest activity and cytotoxicity probably due to its Michael acceptor-dependent microtubule-destabilizing effect and greater GST-inhibitory activity, as well as its enhanced cellular uptake. This work provides useful information for understanding Michael acceptor-dependent and redox-mediated cytotoxic mechanisms of curcumin and its active analogues.

  2. Aza-Peptidyl Michael Acceptor and Epoxide Inhibitors—Potent and Selective Inhibitors of Schistosoma mansoni and Ixodes ricinus Legumains (Asparaginyl Endopeptidases)

    Czech Academy of Sciences Publication Activity Database

    Ovat, A.; Muindi, F.; Fagan, C.; Brouner, M.; Hansell, E.; Dvořák, J.; Sojka, Daniel; Kopáček, Petr; McKerrow, J. H.; Caffrey, C. R.; Powers, J. C.

    2009-01-01

    Roč. 52, č. 22 (2009), s. 7192-7210 ISSN 0022-2623 R&D Projects: GA ČR GA206/06/0865; GA MŠk(CZ) LC06009 Institutional research plan: CEZ:AV0Z60220518 Keywords : legumain * IrAE * aza-peptide Michael acceptors Subject RIV: EC - Immunology Impact factor: 4.802, year: 2009

  3. Aza-peptidyl Michael acceptors. A new class of potent and selective inhibitors of asparaginyl endopeptidases (legumains) from evolutionarily diverse pathogens

    Czech Academy of Sciences Publication Activity Database

    Götz, M. G.; James, K. E.; Hansell, E.; Dvořák, J.; Seshaadri, A.; Sojka, Daniel; Kopáček, Petr; McKerrow, J. H.; Caffrey, C. R.; Powers, J. C.

    2008-01-01

    Roč. 51, č. 9 (2008), s. 2816-2832 ISSN 0022-2623 R&D Projects: GA MŠk(CZ) LC06009; GA ČR GA206/06/0865 Grant - others:The National Institute of Allergy and Infectious Diseases(US) AI053247; National Institute of General Medical Sciences(US) GM54404; National Institute of General Medical Sciences(US) GM61964 Institutional research plan: CEZ:AV0Z60220518 Keywords : legumain * IrAE * aza-peptide Michael acceptors Subject RIV: ED - Physiology Impact factor: 4.898, year: 2008

  4. A facile and efficient method of enzyme immobilization on silica particles via Michael acceptor film coatings: immobilized catalase in a plug flow reactor.

    Science.gov (United States)

    Bayramoglu, Gulay; Arica, M Yakup; Genc, Aysenur; Ozalp, V Cengiz; Ince, Ahmet; Bicak, Niyazi

    2016-06-01

    A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK). The generated double bonds were demonstrated to be an efficient way for rapid incorporation of enzymes via Michael addition. Catalase was used as model enzyme in order to test the effect of immobilization methodology by the reactive film surface through Michael addition reaction. Finally, a plug flow type immobilized enzyme reactor was employed to estimate decomposition rate of hydrogen peroxide. The highly stable enzyme reactor could operate continuously for 120 h at 30 °C with only a loss of about 36 % of its initial activity.

  5. Michael Thonet

    Index Scriptorium Estoniae

    2005-01-01

    Saksa päritolu austria mööblidisaineri ja mööblitöösturi Michael Thonet' (1796-1871) disainiloomingust. 1859. a. Michael Thonet' loodud tool nr. 14 on endiselt tootmises ja on tuntud ka Viini toolina. 2 ill

  6. Michael Scott

    Directory of Open Access Journals (Sweden)

    Ersin Hussein

    2015-04-01

    While Michael has contributed significantly to the field of classics and ancient history by publishing extensively, he has also enjoyed great success in engaging wider audiences with the ancient world. He regularly talks in schools around the country, writes books intended for the popular market as well as articles for national and international newspapers and magazines. Michael's experience in writing and presenting a range of programmes intended for TV and radio audiences has made him a household name. He has written and presented programmes for the National Geographic, History Channel, Nova, and the BBC including Delphi: bellybutton of the ancient world (BBC4; Guilty Pleasures: luxury in the ancient and medieval words (BBC4; Jesus: rise to power (Natural Geographic; Ancient Discoveries (History Channel; Who were the Greeks? (BBC2; The Mystery of the X Tombs (BBC2/Nova; The Greatest Show on Earth (BBC4, in conjunction with the Open University. He has also presented a radio series for BBC Radio 4, Spin the Globe. Michael's most recent programme, Roman Britain from the Air, was aired on ITV in December 2014. In this interview, I talk to him about his engagement with other disciplines within the humanities, his forthcoming book project, and his experiences writing and presenting TV and radio documentaries.

  7. Michael Griffin | NREL

    Science.gov (United States)

    Griffin Photo of Michael Griffin Michael Griffin Researcher III-Chemical Engineering production of high-value products Physical and chemical material characterization under reaction conditions Physical and chemical characterization of catalytic materials Surface science Design and operation of ultra

  8. Michael E. Himmel | NREL

    Science.gov (United States)

    E. Himmel Photo of Michael E. Himmel Michael Himmel Senior Research Fellow I-Molecular Biology biochemistry, recombinant technology, enzyme engineering, new micro-organism discovery, and physicochemistry of

  9. Jack Michael's Motivation

    OpenAIRE

    Miguel, Caio F.

    2013-01-01

    Among many of Jack Michael's contributions to the field of behavior analysis is his behavioral account of motivation. This paper focuses on the concept of motivating operation (MO) by outlining its development from Skinner's (1938) notion of drive. Conceptually, Michael's term helped us change our focus on how to study motivation by shifting its origins from the organism to the environment. Michael's account also served to stimulate applied research and to better understand behavioral functio...

  10. Michael Faraday's Bicentenary.

    Science.gov (United States)

    Williams, L. Pearce; And Others

    1991-01-01

    Six articles discuss the work of Michael Faraday, a chemist whose work revolutionized physics and led directly to both classical field and relativity theory. The scientist as a young man, the electromagnetic experiments of Faraday, his search for the gravelectric effect, his work on optical glass, his laboratory notebooks, and his creative use of…

  11. Following Michael Faraday's Footprints

    Science.gov (United States)

    Galeano, Javier

    2011-01-01

    Last fall I had the good fortune of receiving financial support to shoot a documentary about Michael Faraday. I took the opportunity to learn more about this great experimentalist and to visit the highlights of places in his life. In this paper, I would like to share a list and description of some of the most remarkable places in London suitable…

  12. Michael Faraday, media man.

    Science.gov (United States)

    Fara, Patricia

    2006-03-01

    Michael Faraday was an enthusiastic portrait collector, and he welcomed the invention of photography not only as a possible means of recording observations accurately, but also as a method for advertising science and its practitioners. This article (which is part of the Science in the Industrial Revolution series) shows that like many eminent scientists, Faraday took advantage of the burgeoning Victorian media industry by posing in various roles.

  13. 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,…

  14. Michael Jackson's Sound Stages

    OpenAIRE

    Morten Michelsen

    2012-01-01

    In order to discuss analytically spatial aspects of recorded sound William Moylan’s concept of ‘sound stage’ is developed within a musicological framework as part of a sound paradigm which includes timbre, texture and sound stage. Two Michael Jackson songs (‘The Lady in My Life’ from 1982 and ‘Scream’ from 1995) are used to: a) demonstrate the value of such a conceptualisation, and b) demonstrate that the model has its limits, as record producers in the 1990s began ignoring the conventions of...

  15. Michael Frayn visits CERN

    CERN Multimedia

    2007-01-01

    Award-winning playwright and novelist Michael Frayn gave a guest lecture in the main auditorium at CERN on Friday 15 March about his new book The Human Touch: Our Part in the Creation of the Universe. The lecture focused on cosmology and philosophy and the limitations that language places on our ability to understand the creation of a universe in which we seem to play such a small part. In addition to his novels and plays, which include Copenhagen, a play about the 1941 meeting between German physicist Werner Heisenberg and Danish physicist Niels Bohr, Frayn has translated several works from Russian, including plays by Chekhov and Tolstoy.

  16. Aza-Michael Mono-addition Using Acidic Alumina under Solventless Conditions

    Directory of Open Access Journals (Sweden)

    Giovanna Bosica

    2016-06-01

    Full Text Available Aza-Michael reactions between primary aliphatic and aromatic amines and various Michael acceptors have been performed under environmentally-friendly solventless conditions using acidic alumina as a heterogeneous catalyst to selectively obtain the corresponding mono-adducts in high yields. Ethyl acrylate was the main acceptor used, although others such as acrylonitrile, methyl acrylate and acrylamide were also utilized successfully. Bi-functional amines also gave the mono-adducts in good to excellent yields. Such compounds can serve as intermediates for the synthesis of anti-cancer and antibiotic drugs.

  17. Professor Michael Levitt

    Directory of Open Access Journals (Sweden)

    Gemma-Louise Davies

    2015-10-01

    Full Text Available Professor Michael Levitt (Stanford University, USA won the 2013 Nobel Prize in Chemistry for the development of multiscale models for complex chemical systems—computational tools which can calculate the course of chemical reactions. Professor Levitt was born in Pretoria, South Africa; he came to the UK on a summer vacation aged 16, where he decided to stay and study for his A‑levels. His interest in the physics of living systems drove him to study biophysics at King’s College London, before securing a PhD position at the Laboratory of Molecular Biology in Cambridge. In the interim year between his degree and beginning his PhD, Professor Levitt worked at the Weizmann Institute of Science in Israel, where he met his future wife. They married later that year and moved to Cambridge, where their three children were born. After completing his PhD, he spent time working in Israel, Cambridge, the Salk Institute and Stanford (both California. Since 1986, he has split his time between Israel and California. Outside of science, he is a keen hiker and he is well-known to have attended the eclectic ‘Burning Man’ Festival in California.[1] Professor Levitt visited the University of Warwick to speak at the Computational Molecular Science Annual Conference in March 2015. In this interview, Dr Gemma-Louise Davies, an Institute of Advanced Study Global Research Fellow, spoke to Professor Levitt about the importance of Interdisciplinarity in his field, role models in Academia, and his plans for the future. Image: Professor Michael Levitt (left with Dr Scott Habershon (right, organiser of the 2015 Computational Molecular Science Annual Conference during his visit to the University of Warwick in March 2015. [1] ‘Burning Man’ is a unique annual festival dedicated to community, art, music, self-expression and self-reliance. Tens of thousands of people flock to this temporary metropolis built in the Californian desert.

  18. Michael Levitt and Computational Biology

    Science.gov (United States)

    dropdown arrow Site Map A-Z Index Menu Synopsis Michael Levitt and Computational Biology Resources with Michael Levitt, PhD, professor of structural biology at the Stanford University School of Medicine, has function. ... Levitt's early work pioneered computational structural biology, which helped to predict

  19. En bog om Michael Strunge

    DEFF Research Database (Denmark)

    Mai, Anne-Marie

    Antologi med bidrag om Michael Strunges forfatterskab. Bidrag af Anne-Marie Mai, Jørgen Aabenhus, Marianne Stidsen, Moritz Schramm, Tue Andersen Nexø, Lars Bukdahl, Jon Helt Haarder, Rune Kühl er optaget efter fagfællesbedømmelse. Antologien er redigeret af Anne-Marie Mai og Jørgen Aabenhus....

  20. Michael Beitz: Objects of Communication

    Science.gov (United States)

    Hoefferle, Mary

    2014-01-01

    For this Instructional Resource, the author interviewed contemporary sculptor Michael Beitz, who uses art to explore the role of designed objects in human communication and emotional experience. This column was written in response to calls for using Enduring Understandings/Big Ideas (National Coalition for Core Arts Standards, 2013; Stewart &…

  1. Radiation curable Michael addition compounds

    International Nuclear Information System (INIS)

    Gruber, G.W.; Friedlander, C.B.; McDonald, W.H.; Dowbenko, R.

    1979-01-01

    Radiation polymerizable acrylyloxy-containing reaction products are provided from Michael addition reaction of an amide containing at least two acrylate groups with a primary or secondary amine. The resulting amine adducts of the amide, which contain at least one acrylate group per molecule, possesses high cure rates in air and are useful in compositions for forming coatings. (author)

  2. A Greener, Efficient Approach to Michael Addition of Barbituric Acid to Nitroalkene in Aqueous Diethylamine Medium

    Directory of Open Access Journals (Sweden)

    Hany J. Al-Najjar

    2014-01-01

    Full Text Available An efficient method for the synthesis of a variety of pyrimidine derivatives 3a–t by reaction of barbituric acids 1a,b as Michael donor with nitroalkenes 2a–k as Michael acceptor using an aqueous medium and diethylamine is described. This 1,4-addition strategy offers several advantages, such as using an economic and environmentally benign reaction media, high yields, versatility, and shorter reaction times. The synthesized compounds were identified by 1H-NMR, 13C-NMR, CHN, IR, and MS. The structure of compound 3a was further confirmed by single crystal X-ray structure determination.

  3. Michael J. Fox: Spurring Research on Parkinson's

    Science.gov (United States)

    ... turn JavaScript on. Feature: Parkinson's Disease Michael J. Fox: Spurring Research on Parkinson's Past Issues / Winter 2014 Table of Contents Michael J. Fox and his wife, actress Tracy Pollan, founded the ...

  4. Michael Faraday vs. the Spiritualists

    Science.gov (United States)

    Hirshfeld, Alan

    2006-12-01

    In the 1850s, renowned physicist Michael Faraday launched a public campaign against pseudoscience and spiritualism, which were rampant in England at the time. Faraday objected especially to claims that electrical or magnetic forces were responsible for paranormal phenomena, such as table-spinning and communication with the dead. Using scientific methods, Faraday unmasked the deceptions of spiritualists, clairvoyants and mediums and also laid bare the credulity of a public ill-educated in science. Despite his efforts, Victorian society's fascination with the paranormal swelled. Faraday's debacle anticipates current controversies about public science education and the interface between science and religion. This episode is one of many described in the new biography, The Electric Life of Michael Faraday (Walker & Co.), which chronicles Faraday's discoveries and his unlikely rise from poverty to the pinnacle of the English science establishment.

  5. Michael Niegl (1985-2009)

    CERN Multimedia

    2009-01-01

    Our friend and colleague Michael Niegl died in a tragic accident in the first hours of the new year. Michael was a Master’s student in Microsystems Engineering at the University of Applied Sciences Wiener Neustadt. He was responsible for the development of the ATLAS Beam Conditions Monitor (BCM) ROD FPGA firmware, which acquires the data from the BCM detector modules and provides online monitoring of the LHC beams within the ATLAS experiment. He spent several months at CERN to carry out beam tests on the BCM detectors and received his Bachelor of Science with first class honours for his thesis: Concept and Implementation of an FPGA-based Data Recorder and Processor for the ATLAS Beam Conditions Monitor. Michael spent six months at CERN last year to finish the development and commissioning of the ROD firmware for the first beam. He worked the entire night of 10 September to fine tune the system for the first beam. It was a joy to ...

  6. Michael De Sousa (1989 - 2012)

    CERN Multimedia

    2012-01-01

    We are deeply saddened to announce the death of Mr Michael De Sousa on 13 May 2012. Mr De Sousa, who was born on 02.09.1989, was working as an apprentice in the TE Department and had been at CERN since 24.08.2009. The Director-General has sent a message of condolence to his family on behalf of the CERN personnel. Social Affairs Human Resources Department     It is with great emotion and deep sadness that we learn of the tragic loss of our colleague and friend Michael De Sousa. Michael was a hard working colleague, cordial and considerate. Within a few months, he marked his presence by the implementation of the instrumentation benches for gas permeation measurement in polymers, and the calibration of high technology gas analyzers, necessary for vacuum technology. His last contribution will enable us to measure pressures in the extreme high vacuum range for the ELENA project.  With the continuation of this activity, his memory will remain. His accomplishments will remain...

  7. Organocatalytic aza-Michael/retro-aza-Michael reaction: pronounced chirality amplification in aza-Michael reaction and racemization via retro-aza-Michael reaction.

    Science.gov (United States)

    Cai, Yong-Feng; Li, Li; Luo, Meng-Xian; Yang, Ke-Fang; Lai, Guo-Qiao; Jiang, Jian-Xiong; Xu, Li-Wen

    2011-05-01

    A detailed experimental investigation of an aza-Michael reaction of aniline and chalcone is presented. A series of Cinchona alkaloid-derived organocatalysts with different functional groups were prepared and used in the aza-Michael and retro-aza-Michael reaction. There was an interesting finding that a complete reversal of stereoselectivity when a benzoyl group was introduced to the cinchonine and cinchonidine. The chirality amplification vs. time proceeds in the quinine-derived organocatalyst containing silicon-based bulky group, QN-TBS, -catalyzed aza-Michael reaction under solvent-free conditions. In addition, we have demonstrated for the first time that racemization was occurred in suitable solvents under mild conditions due to retro-aza-Michael reaction of the Michael adduct of aniline with chalcone. These indicate the equilibrium of retro-aza-Michael reaction and aza-Michael reaction produce the happening of chirality amplification in aza-Michael reaction and racemization via retro-aza-Michael reaction under different conditions, which would be beneficial to the development of novel chiral catalysts for the aza-Michael reactions. Copyright © 2011 Wiley-Liss, Inc.

  8. Michael Jackson antes del caos

    OpenAIRE

    Juan Luciano Nieves

    2015-01-01

    Michael Jackson es un buen ejemplo de cómo utilizar las relaciones públicas para realizar o manipular la imagen de un producto a través de los medios de comunicación. Este ensayo pretende analizar los eventos que tuvieron lugar antes de que el cantante fuera acusado de abuso sexual contra un menor. Dichos eventos formaron parte de un plan muy bien delineado para disminuir los efectos de la inminente crisis que se acercaba. Este trabajo combina la crítica retórica de temas de fantasía con teor...

  9. Video interview with Michael Dell

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Michael Dell, founder and presently Chairman of the Board of Directors and Chief Executive Office of the DELL computer company visited CERN on Tuesday 26th January 2010. The Bulletin and the Video productions team had the opportunity to meet him. The video interview is transcribed for your convenience.   Michael S. Dell with CERN Director-General Rolf Heuer. What motivated you to come and visit CERN? I obviously heard about the great science and research has going on here, and DELL is very pleased to be a partner and providing a lot of the computers to analyse the data and I really wanted to see for myself in person, some of the great science that is going on here. What is your view on fundamental research in IT, and in general? I think if you look at the field of science in the last hundred years, we have been able to solve a lot of problems, but there are still lots of unsolved problems and unsolved mysteries. And it is only through basic fundamental research that we will address these probl...

  10. Michael Jackson antes del caos

    Directory of Open Access Journals (Sweden)

    Juan Luciano Nieves

    2015-01-01

    Full Text Available Michael Jackson es un buen ejemplo de cómo utilizar las relaciones públicas para realizar o manipular la imagen de un producto a través de los medios de comunicación. Este ensayo pretende analizar los eventos que tuvieron lugar antes de que el cantante fuera acusado de abuso sexual contra un menor. Dichos eventos formaron parte de un plan muy bien delineado para disminuir los efectos de la inminente crisis que se acercaba. Este trabajo combina la crítica retórica de temas de fantasía con teoría de comunicación.

  11. Jack Michael's Motivation

    Science.gov (United States)

    Miguel, Caio F.

    2013-01-01

    Among many of Jack Michael's contributions to the field of behavior analysis is his behavioral account of motivation. This paper focuses on the concept of "motivating operation" (MO) by outlining its development from Skinner's (1938) notion of "drive." Conceptually, Michael's term helped us change our focus on…

  12. Isoindolinones as Michael Donors under Phase Transfer Catalysis: Enantioselective Synthesis of Phthalimidines Containing a Tetrasubstituted Carbon Stereocenter

    Directory of Open Access Journals (Sweden)

    Francesco Scorzelli

    2015-05-01

    Full Text Available Readily available chiral ammonium salts derived from cinchona alkaloids have proven to be effective phase transfer catalysts in the asymmetric Michael reaction of 3-substituted isoindolinones. This protocol provides a convenient method for the construction of valuable asymmetric 3,3-disubstituted isoindolinones in high yields and  moderate to good enantioselectivity. Diastereoselectivity was also investigated in the construction of contiguous tertiary and quaternary stereocenters. The use of acrolein as Michael acceptor led to an interesting tricyclic derivative, a pyrroloisoindolinone analogue, via a tandem conjugated addition/cyclization reaction.

  13. Organocatalytic Asymmetric Michael Addition of 4-Hydroxycoumarin to β,γ-Unsaturated α-Keto Esters

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Chang Won; Han, Tae Hyun; Kim, Dae Young [Soonchunhyang Univ., Asan (Korea, Republic of)

    2013-06-15

    In conclusion, we have developed organocatalytic enantioselective conjugate addition reaction of 4-hydroxycoumarin (1) to β,γ-unsaturated α-keto esters 2 to afford biologically valuable warfarin derivatives 3. The process is efficiently catalyzed by a binaphthyl-modified thiourea organocatalyst. The coumarin core is present as a characteristic structural motif in a large number of natural products and biologically active molecules.1 Particularly, many of these naturally occurring 4-hydroxycoumarin and their synthetic analogues are important precursors for the synthesis of natural products and pharmaceuticals. Enantioselective organocatalytic conjugate addition of 4-hydroxycoumarin to α,β-unsaturated ketones is a straightforward method to access warfarin which is an effective anticoagulants. Although a number of reactions of α,β-unsaturated ketones as Michael acceptors have been reported, the corresponding β,γ-unsaturated α-keto esters have received relatively little attention as Michael acceptors. Recently, several groups have reported the asymmetric Michael addition of 4-hydroxycoumarin to β,γ-unsaturated α-keto esters catalyzed by Cu(II)-bisoxazoline, N,N'-dioxide-Ni(II) complexes, thiourea catalysts. Although several efficient methods have been achieved by these systems, an effective method for the synthesis of warfarin analogues is still a challenge.

  14. Organocatalytic Asymmetric Michael Addition of 4-Hydroxycoumarin to β,γ-Unsaturated α-Keto Esters

    International Nuclear Information System (INIS)

    Suh, Chang Won; Han, Tae Hyun; Kim, Dae Young

    2013-01-01

    In conclusion, we have developed organocatalytic enantioselective conjugate addition reaction of 4-hydroxycoumarin (1) to β,γ-unsaturated α-keto esters 2 to afford biologically valuable warfarin derivatives 3. The process is efficiently catalyzed by a binaphthyl-modified thiourea organocatalyst. The coumarin core is present as a characteristic structural motif in a large number of natural products and biologically active molecules.1 Particularly, many of these naturally occurring 4-hydroxycoumarin and their synthetic analogues are important precursors for the synthesis of natural products and pharmaceuticals. Enantioselective organocatalytic conjugate addition of 4-hydroxycoumarin to α,β-unsaturated ketones is a straightforward method to access warfarin which is an effective anticoagulants. Although a number of reactions of α,β-unsaturated ketones as Michael acceptors have been reported, the corresponding β,γ-unsaturated α-keto esters have received relatively little attention as Michael acceptors. Recently, several groups have reported the asymmetric Michael addition of 4-hydroxycoumarin to β,γ-unsaturated α-keto esters catalyzed by Cu(II)-bisoxazoline, N,N'-dioxide-Ni(II) complexes, thiourea catalysts. Although several efficient methods have been achieved by these systems, an effective method for the synthesis of warfarin analogues is still a challenge

  15. Acceptors in ZnO

    Energy Technology Data Exchange (ETDEWEB)

    McCluskey, Matthew D., E-mail: mattmcc@wsu.edu; Corolewski, Caleb D.; Lv, Jinpeng; Tarun, Marianne C.; Teklemichael, Samuel T. [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States); Walter, Eric D. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Norton, M. Grant; Harrison, Kale W. [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 (United States); Ha, Su [Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164-6515 (United States)

    2015-03-21

    Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on acceptors. In this paper, Cu, N, and Li acceptor impurities are discussed. Experimental evidence indicates these point defects have acceptor levels 3.2, 1.4, and 0.8 eV above the valence-band maximum, respectively. The levels are deep because the ZnO valence band is quite low compared to conventional, non-oxide semiconductors. Using MoO{sub 2} contacts, the electrical resistivity of ZnO:Li was measured and showed behavior consistent with bulk hole conduction for temperatures above 400 K. A photoluminescence peak in ZnO nanocrystals is attributed to an acceptor, which may involve a Zn vacancy. High field (W-band) electron paramagnetic resonance measurements on the nanocrystals revealed an axial center with g{sub ⊥} = 2.0015 and g{sub //} = 2.0056, along with an isotropic center at g = 2.0035.

  16. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 3: Michael addition reactions and miscellaneous transformations.

    Science.gov (United States)

    Aceña, José Luis; Sorochinsky, Alexander E; Soloshonok, Vadim

    2014-09-01

    The major goal of this review is a critical discussion of the literature data on asymmetric synthesis of α-amino acids via Michael addition reactions involving Ni(II)-complexes of amino acids. The material covered is divided into two conceptually different groups dealing with applications of: (a) Ni(II)-complexes of glycine as C-nucleophiles and (b) Ni(II)-complexes of dehydroalanine as Michael acceptors. The first group is significantly larger and consequently subdivided into four chapters based on the source of stereocontrolling element. Thus, a chiral auxiliary can be used as a part of nucleophilic glycine Ni(II) complex, Michael acceptor or both, leading to the conditions of matching vs. mismatching stereochemical preferences. The particular focus of the review is made on the practical aspects of the methodology under discussion and mechanistic considerations.

  17. Aza‐Michael addition reaction: Post‐polymerization modification and preparation of PEI/PEG‐based polyester hydrogels from enzymatically synthesized reactive polymers

    DEFF Research Database (Denmark)

    Hoffmann, Christian; Stuparu, Mihaiela C.; Daugaard, Anders Egede

    2015-01-01

    The utility of aza‐Michael addition chemistry for post‐polymerization functionalization of enzymatically prepared polyesters is established. For this, itaconate ester and oligoethylene glycol are selected as monomers. A Candida Antarctica lipase B catalyzed polycondensation reaction between the two...... monomers provides the polyesters, which carry an activated carbon‐carbon double bond in the polymer backbone. These electron deficient alkenes represent suitable aza‐Michael acceptors and can be engaged in a nucleophilic addition reaction with small molecular mono‐amines (aza‐Michael donors) to yield...... functionalized linear polyesters. Employing a poly‐amine as the aza‐Michael donor, on the other hand, results in the formation of hydrophilic polymer networks....

  18. Michael Wood’s Yangzhou Dream

    Institute of Scientific and Technical Information of China (English)

    Yuan; Dan

    2014-01-01

    <正>Mr.Michael Wood is a wellknown British historian and documentary maker who has produced more than a hundred documentaries on various national histories and cultures exemplified by The Story of India.They enjoy wide popularity in more than 150 countries.I met him in February when he took his fi lm crew to Yangzhou to shoot The Story of China documentary for the British Broadcasting Corporation(BBC).It was a snowy day,cold and wet,but Michael said happily that the

  19. Michael Tomasello: Award for Distinguished Scientific Contributions.

    Science.gov (United States)

    2015-11-01

    The APA Awards for Distinguished Scientific Contributions are presented to persons who, in the opinion of the Committee on Scientific Awards, have made distinguished theoretical or empirical contributions to basic research in psychology. One of the 2015 award winners is Michael Tomasello, who received this award for "outstanding empirical and theoretical contributions to understanding what makes the human mind unique. Michael Tomasello's pioneering research on the origins of social cognition has led to revolutionary insights in both developmental psychology and primate cognition." Tomasello's award citation, biography, and a selected bibliography are presented here. (c) 2015 APA, all rights reserved).

  20. Michael Heyrovsky, in memoriam (1932-2017)

    Czech Academy of Sciences Publication Activity Database

    Barek, J.; Černý, Slavoj; Herman, Zdeněk; Jindra, Jiří; Paleček, Emil

    2017-01-01

    Roč. 29, č. 8 (2017), s. 2001-2002 ISSN 1040-0397 Institutional support: RVO:68378114 ; RVO:61388955 ; RVO:68081707 Keywords : Michael Heyrovský Subject RIV: AB - History OBOR OECD: History (history of science and technology to be 6.3, history of specific sciences to be under the respective headings) Impact factor: 2.851, year: 2016

  1. Reframing Michael Scott: Exploring Inappropriate Workplace Communication

    Science.gov (United States)

    Schaefer, Zachary A.

    2010-01-01

    Individuals who work in professional settings interact with others who may exhibit a variety of cultural beliefs and decision-making approaches. Page (2007) argues that cognitive diversity (i.e., how people approach and attempt to solve problems) is a vital asset in effective organizations. Michael Scott, who portrays the inept main character on…

  2. Michael Hauskeller: Sex and the Posthuman Condition

    NARCIS (Netherlands)

    Miller, Lantz Eugene

    2016-01-01

    This new book from Michael Hauskeller explores the currently marketed or projected sex/love products that exhibit some trait of so-called “posthumanistic” theory or design. These products are so designated because of their intention to fuse high technologies, including robotics and computing, with

  3. Aza-Michael reaction: achievements and prospects

    International Nuclear Information System (INIS)

    Rulev, Alexander Yu

    2011-01-01

    Data published in the last 10 years on the use of the aza-Michael reaction in organic synthesis are described systematically. The attention is focused on environmentally friendly processes following green chemistry principles and on methods for the synthesis of compounds that are difficult to access by other routes.

  4. Tetrabutylammonium Bromide Media Aza-Michael Addition of 1,2,3,6-Tetrahydrophthalimide to Symmetrical Fumaric Esters and Acrylic Esters under Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Mohammadreza Zamanloo

    2010-10-01

    Full Text Available The aza-Michael addition of 1,2,3,6-tetrahydrophthalimide with symmetrical fumaric esters has been performed efficiently in a solvent-free system at 100 °C and using 1,4-diazabicyclo[2.2.2]octane (DABCO as a base in the presence of tetrabutylammonium bromide (TBAB. The products were obtained in good to high yields within 2.5-7.0 h. This reaction worked well on linear alkyl fumarates and was not effective with nonlinear alkyl fumarates. Although the reaction was also applicable to acrylates such as n-butyl acrylate, methacrylates and crotonates were not suitable Michael acceptors for this reaction.

  5. Michael Haneke film Euroopa parim / M. T.

    Index Scriptorium Estoniae

    M. T.

    2005-01-01

    IX PÖFFil linastuv Michael Haneke film "Varjatud" ("Cache") võitis laupäeval mitu Euroopa Filmiakadeemia auhinda, selhulgas parima filmi, parima lavastaja, parima meesnäitleja (Daniel Auteuil) ja FIPRESCI auhinna. Parim naisnäitleja - Julia Jentsch ("Sophie Scholli viimased päevad"), operaator - Franz Lustig ("Don't Come Knocking"), stsenaarium - Hany Abu-Assad, Bero Beyer ("Kohe paradiisi")

  6. Obituary: Michael James Ledlow, 1964-2004

    Science.gov (United States)

    Puxley, Philip John; Grashuis, Randon M.

    2004-12-01

    Michael James Ledlow died on 5 June 2004 from a large, unsuspected brain tumor. Since 2000 he had been on the scientific staff of the Gemini Observatory in La Serena, Chile, initially as a Science Fellow and then as a tenure-track astronomer. Michael was born in Bartlesville, Oklahoma on 1 October 1964 to Jerry and Sharon Ledlow. He obtained his Bachelor Degree in astrophysics at the University of Oklahoma in 1987 and attended the University of New Mexico for his graduate work, obtaining his PhD while studying Galaxy Clusters under Frazer Owen in 1994. From 1995-1997 Michael held a postdoctoral position with Jack Burns at New Mexico State University where he used various astronomical facilities including the VLA and Apache Point Observatory to study distant galaxies. From 1998-2000 Michael rejoined the Physics and Astronomy Department at the University of New Mexico where he was a visiting professor until he moved on to Gemini. At the Gemini Observatory, Mike shared in the excitement, hard work and many long days and nights associated with bringing on-line a major new astronomical facility and its instrumentation. Following its commissioning he assisted visiting observers, supported and took data for many more remote users via the queue system, and for each he showed the same care and attention to detail evident in his own research to ensure that all got the best possible data. His research concentrated on the radio and optical properties of galaxy clusters, especially rich Abell clusters such as A2125, on luminous radio galaxies, including the detection of a powerful double radio source in the "wrong sort of galaxy," the spiral system 0313-192, and on EROs (extremely red objects), dusty galaxies barely detectable at optical wavelengths. Michael thoroughly enjoyed living in Chile and enthusiastically immersed himself in the culture of his surroundings. He and his family were actively involved with the International English Spanish Association in La Serena. He had a

  7. COMPARISON OF ACCEPTOR PROPERTIES FOR INTERACTION ...

    African Journals Online (AJOL)

    Preferred Customer

    determined by UV-Vis titration method for the adducts. Surprisingly, the ... Interaction of. TCNE and DDQ as π-acceptors with hydrocarbon donors such as cycloalkanes, alkenes, ... obtained from a Shimadzu GC-MS model QP5050 instrument.

  8. Michael Roitmann : Kalandus ei ole Eestile ilmselt prioriteetne valdkond / Michael Roitmann ; interv. Marko Saaret

    Index Scriptorium Estoniae

    Roitmann, Michael

    2003-01-01

    Ilmunud ka: Delovõje Vedomosti 3. dets. lk. 9. Euroopa Komisjoni kalandusdirektoraadi koordinaator Euroopa Liidu laienemise küsimuses Michael Roitmann juhib tähelepanu Eesti kalanduse suurematele probleemidele ning prognoosib EL-iga liitumise mõju Eesti kalandussektori arengule

  9. Michael Maier--nine newly discovered letters.

    Science.gov (United States)

    Lenke, Nils; Roudet, Nicolas; Tilton, Hereward

    2014-02-01

    The authors provide a transcription, translation, and evaluation of nine newly discovered letters from the alchemist Michael Maier (1568-1622) to Gebhardt Johann von Alvensleben (1576-1631), a noble landholder in the vicinity of Magdeburg. Stemming from the final year of his life, this correspondence casts new light on Maier's biography, detailing his efforts to secure patronage amid the financial crisis of the early Thirty Years' War. While his ill-fated quest to perfect potable gold continued to form the central focus of his patronage suits, Maier also offered his services in several arts that he had condemned in his printed works, namely astrology and "supernatural" magic. Remarks concerning his previously unknown acquaintance with Heinrich Khunrath call for a re-evaluation of Maier's negotiation of the discursive boundaries between Lutheran orthodoxy and Paracelsianism. The letters also reveal Maier's substantial contribution to a work previously ascribed solely to the English alchemist Francis Anthony.

  10. 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......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...

  11. Interview with Michael Apple: The Biography of a Public Intellectual

    Science.gov (United States)

    Peters, Michael A.

    2015-01-01

    Michael W. Apple is the John Bascom Professor of Curriculum and Instruction and Educational Policy Studies in the Departments of Curriculum and Instruction (CI) and Educational Policy Studies (EPS) at the University of Wisconsin-Madison School of Education where he has taught since 1970. Michael Apple is one of the foremost educational theorists…

  12. Book Review: Invitation to Topological Robotics by Michael Farber

    DEFF Research Database (Denmark)

    Raussen, Martin

    2009-01-01

    Book Review: Invitaton to Topological Robotics by Michael Farber. Zurich Lectures in Advanced Mathematics, European Mathematical Society (2008), ISBN 978-3-03719-054-8......Book Review: Invitaton to Topological Robotics by Michael Farber. Zurich Lectures in Advanced Mathematics, European Mathematical Society (2008), ISBN 978-3-03719-054-8...

  13. Sterilisation: characteristics of vasectomy acceptors in Delhi.

    Science.gov (United States)

    Sarkar, N N

    1993-01-01

    The place of vasectomy within the sterilisation programme in Delhi over the period 1983-88 is reviewed and data on vasectomy acceptance and characteristics of acceptors are analysed. Findings suggest a need to improve the strategy for the promotion of vasectomy within the metropolis.

  14. 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.

  15. Obituary: Michael John Klein, 1940-2005

    Science.gov (United States)

    Gulkis, Samuel

    2006-12-01

    Michael John Klein died on 14 May 2005 at home in South Pasadena, California. The cause of death was tongue cancer that metastasized to the lungs. He was a non-smoker. Mike was a passionate radio astronomer, a trusted astronomical observer, an educator and a family man. Mike was born on 19 January 1940 in Ames, Iowa, the son of Florence Marie (Graf) and Fred Michael Klein. His mother was a homemaker, and his father was a banker. Mike had two older sisters, Lois Jean (Klein) Flauher and Marilyn June (Klein) Griffin. In 1962, Mike married his high school sweetheart Barbara Dahlberg, who survives him along with their three children, Kristin Marie (Klein) Shields, Michael John Klein Jr., Timothy Joel Klein, and six grandchildren. Mike developed a love for astronomy early in his life, and credited an early morning, newspaper-delivery route that he had at age twelve, which took him outside well before sunrise. He told family members that as he walked along his route, he stared into the sky and wondered what everything was. He studied sky charts, located stars, and began to understand how the planets shifted their positions relative to the stars each day. Another big influence in Mike's life was his brother in-law, Jim Griffin. Jim helped Mike understand that his passion for science did not have to remain a hobby, but could and should become a career. Jim's encouragement led Mike to attend Iowa State University in Ames, where he earned a BS in electrical engineering in 1962. Mike then started graduate school in electrical engineering at Michigan State, but after one semester transferred to the University of Michigan, Ann Arbor, where he earned an MS (1966) and PhD (1968) in astronomy. His doctoral dissertation, under the direction of Professor Fred Haddock, was based on extensive observations of the planets and examined the physical and thermal properties of planetary atmospheres and surfaces. Mike was awarded a Resident Research Associate position at JPL by the National

  16. Race, punishment, and the Michael Vick experience.

    Science.gov (United States)

    Piquero, Alex R; Piquero, Nicole Leeper; Gertz, Marc; Baker, Thomas; Batton, Jason; Barnes, J C

    2011-01-01

    Objective. The relationship between race and crime has been contentious, focusing primarily on offending and incarceration patterns among minorities. There has been some limited work on public perceptions of criminal punishment, and findings show that while minorities believe in the role and rule of law, they simultaneously perceive the justice system as acting in a biased and/or unfair manner. Two limitations have stalled this literature. First, research has focused mainly on criminal punishments to the neglect of noncriminal punishments. Second, most studies have not examined whether race remains salient after considering other demographic variables or discrimination and legitimacy attitudes.Methods. Using data from 400 adults, we examine how race affects perceptions of criminal punishment and subsequent reinstatement into the National Football League in the case of Michael Vick, a star professional quarterback who pled guilty to charges of operating an illegal dog-fighting ring.Results. Findings show that whites are more likely to view Vick's punishment as too soft and that he should not be reinstated, while nonwhites had the opposite views. Race remained significant after controlling for other variables believed to be related to punishment perceptions.Conclusion. Attitudes toward both criminal punishment and NFL reinstatement vary across race such that there exists important divides in how individuals perceive the system meting out punishment and subsequently reintegrating offenders back into society. These results underscore that white and nonwhites perceive the law and its administration differently.

  17. Non-fullerene electron acceptors for organic photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. 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.

  19. Michael Polanyi: Patriarch of Chemical Dynamics and Tacit Knowing.

    Science.gov (United States)

    Herschbach, Dudley R

    2017-03-20

    Connecting Science and the Humanities was the title of the symposium on Michael Polanyi that took place at the Technische Universität Berlin (Technical University of Berlin) in October 2016. This essay, which appraises the scientific and philosophical contributions of Michael Polanyi, is based on the presentation given by Dr. Herschbach on this occasion. In the photograph: Polanyi in 1931. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Principles of Chemistry (by Michael Munowitz)

    Science.gov (United States)

    Kovac, Reviewed By Jeffrey

    2000-05-01

    At a time when almost all general chemistry textbooks seem to have become commodities designed by marketing departments to offend no one, it is refreshing to find a book with a unique perspective. Michael Munowitz has written what I can only describe as a delightful chemistry book, full of conceptual insight, that uses a novel and interesting pedagogic strategy. This is a book that has much to recommend it. This is the best-written general chemistry book I have ever read. An editor with whom I have worked recently remarked that he felt his job was to help authors make their writing sing. Well, the writing in Principles of Chemistry sings with the full, rich harmonies and creative inventiveness of the King's Singers or Chanticleer. Here is the first sentence of the introduction: "Central to any understanding of the physical world is one discovery of paramount importance, a truth disarmingly simple yet profound in its implications: matter is not continuous." This is prose to be savored and celebrated. Principles of Chemistry has a distinct perspective on chemistry: the perspective of the physical chemist. The focus is on simplicity, what is common about molecules and reactions; begin with the microscopic and build bridges to the macroscopic. The author's perspective is clear from the organization of the book. After three rather broad introductory chapters, there are four chapters that develop the quantum mechanical theory of atoms and molecules, including a strong treatment of molecular orbital theory. Unlike many books, Principles of Chemistry presents the molecular orbital approach first and introduces valence bond theory later only as an approximation for dealing with more complicated molecules. The usual chapters on descriptive inorganic chemistry are absent (though there is an excellent chapter on organic and biological molecules and reactions as well as one on transition metal complexes). Instead, descriptive chemistry is integrated into the development of

  1. 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.

  2. Guest Foreword from Michael Thomas CMG QC

    Directory of Open Access Journals (Sweden)

    Michael Thomas

    2012-04-01

    precedents and thought in a unique legal market in which ideas drawn from Islamic law, civil law and common law can intermingle and blend. It is not surprising therefore to see that this new publication will be dedicated to the subject of international law, both public and private. Its laudable aim is to promote legal discourse around the world, and to promote a wider international understanding of contemporary legal issues for the common benefit. As an open access, bilingual journal, addressing topics concerning any jurisdiction, I hope it will reach a wide audience, and fulfil its aim of promoting understanding between different cultures. I am sure that the journal will not only benefit Qatar’s legal community by advancing academic and practice-based legal discussion. I am also confident that it will stimulate thought in the global legal community at large. May I wish it every success and a long life. Michael Thomas CMG QC

  3. 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

  4. A study of acceptors and non-acceptors of family planning methods among three tribal communities.

    Science.gov (United States)

    Mutharayappa, R

    1995-03-01

    Primary data were collected from 399 currently married women of the Marati, Malekudiya, and Koraga tribes in the Dakshina Kannada district of Karnataka State in this study of the implementation of family planning programs in tribal areas. The Marati, Malekudiya, and Koraga tribes are three different endogamous tribal populations living in similar ecological conditions. Higher levels of literacy and a high rate of acceptance of family planning methods, however, have been observed among these tribes compared to the rest of the tribal population in the state. 46.4% of currently married women aged 15-49 years in the tribes were acceptors of family planning methods, having a mean 3.7 children. The majority of acceptors opted for tubectomy and vasectomy. The adoption of spacing methods is less common among tribal people. Most acceptors received their operations through government health facilities. They were motivated mainly by female health workers and received both cash and other incentives to accept family planning. The main reason for non-acceptance of family planning among non-acceptors was the desire to conceive and bear more children. The data indicate that most of the tribal households are nuclear families with household size more or less similar to that of the general population. They have a higher literacy rate than the rest of the tribal population in the state, with literacy levels between males and females and between the three tribes being quite different; the school enrollment ratio is relatively higher for both boys and girls.

  5. Obituary: Michael John Seaton, 1923-2007

    Science.gov (United States)

    Pradhan, Anil; Nahar, Sultana

    2007-12-01

    Professor Michael John Seaton, hailed as the "Father of Atomic Astrophysics," passed away on May 29, 2007. He was one of the few Honorary Fellows of both the American Astronomical Society and the American Physical Society, so honored for his monumental contributions to both physics and astronomy. Mike Seaton was born on January 16, 1923 in Bristol, England. He attended Wallington County High School. But his leftist political activities, even at that stage, led to his expulsion, though he was eventually allowed to matriculate. He enlisted in the Royal Air Force as a navigator during the Second World War, and flew many dangerous missions. His legendary concentration and precision are reflected in the following anecdote. Once after a bombing mission his aircraft was lost in fog over the Alps. Seaton calculated the position and coordinates in flight to guide the aircraft. When the fog lifted, the crew found themselves flying perilously close to the mountains, but made it safely back. His associates often said, "A Seaton calculation is carried out as if his life depended on it." After the War he was admitted to University College London (UCL) as an undergraduate. Thereafter, he spent all of his professional career at UCL. Seaton received his Batchelor's degree in 1948, and his Ph.D. in 1951. His tenure at UCL coincided with the golden age of atomic astrophysics, for he was largely responsible for it. Seaton was elected Fellow of the Royal Society in 1967, and as President of the Royal Astronomical Society (RAS) in 1978. He was the recipient of an Honorary Doctorate from the Observatoire de Paris, an Honorary D.Sc. from the Queen's University of Belfast, the Gold Medal for Astronomy by the RAS, the Guthrie Medal by the Institute of Physics, the Royal Society Hughes award for lifetime work by the RAS, and several other prestigious awards. Nevertheless, as Alex Dalgarno recently remarked, Seaton was not part of the establishment because he chose not to be. Though rooted in

  6. On the effect of nuclear bridge modes on donor-acceptor electronic coupling in donor-bridge-acceptor molecules

    International Nuclear Information System (INIS)

    Davis, Daly; Toroker, Maytal Caspary; Speiser, Shammai; Peskin, Uri

    2009-01-01

    We report a theoretical study of intra-molecular electronic coupling in a symmetric DBA (donor-bridge-acceptor) complex, in which a donor electronic site is coupled to an acceptor site by way of intervening orbitals of a molecular bridge unit. In the off-resonant (deep tunneling) regime of electronic transport, the lowest unoccupied molecular orbitals (MO's) of the DBA system are split into distinguishable donor/acceptor and bridge orbitals. The effect of geometrical changes at the bridge on the donor/acceptor electronic energy manifold is studied for local stretching and bending modes. It is demonstrated that the energy splitting in the manifold of donor/acceptor unoccupied MOs changes in response to such changes, as assumed in simple McConnell-type models. Limitations of the simple models are revealed where the electronic charging of the bridge orbitals correlates with increasing donor/acceptor orbital energy splitting only for stretching but not for bending bridge modes.

  7. Physics of positronium acceptor complex formation reactions

    International Nuclear Information System (INIS)

    Gangopadhyay, Debarshi; Ganguly, Bichitra Nandi; Mukherjee, Tapas; Dutta-Roy, Binayak

    2002-01-01

    Positronium (P s ) reaction rates (κ) with weak Acceptors (Ac) leading to the formation of Ps-Ac complexes show several interesting features: non-monotonic temperature dependence of κ(departing from the usual Arrhenius behaviour), considerable variability of κ with respect to different solvents, and anomalies in response to external pressure at ambient temperature. The object of this work is to explain all these phenomena using a remarkably simple bubble model (the widely used model for the pick-off component of ortho-positronium decay in liquids), which has been revisited several times in the context and as a result smooth diffuse boundary of the bubble was suggested that yields reasonable agreement of the experimental data. The contractile force on the bubble relies much on the surface tension of the liquid, through our calculation the notion of critical surface tension emerges and enables us to explain the experimental observations satisfactorily. (author)

  8. 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.

  9. Tweeting Prayers and Communicating Grief over Michael Jackson Online

    Science.gov (United States)

    Sanderson, Jimmy; Cheong, Pauline Hope

    2010-01-01

    Death and bereavement are human experiences that new media helps facilitate alongside creating new social grief practices that occur online. This study investigated how people's postings and tweets facilitated the communication of grief after pop music icon Michael Jackson died. Drawing on past grief research, religion, and new media studies, a…

  10. Professor Porter ja tema viis konkurentsitegurit / Michael E Porter

    Index Scriptorium Estoniae

    Porter, Michael E

    2008-01-01

    Maailmas tuntud juhtimisguru Michael Porter viie konkurentsijõu teooriast ja selle rakendatavusest erinevates valdkondades. Lisad: Erinevused valdkondade kasumlikkuses; 5 määravat konkurentsijõudu; Investeeritud kapitali keskmine tasuvus; Mõnede USA tegevusvaldkondade kasumlikkus; Valdkonnaanalüüs praktikas; Valdkonna määratlemine; Valdkonnaanalüüsi sammud

  11. A Good Time: A Conversation with C. Michael Nelson

    Science.gov (United States)

    Zabel, Robert; Kaff, Marilyn; Teagarden, Jim

    2015-01-01

    C. Michael Nelson began his special education career as a teacher of adolescents with learning and behavior disorders. He has worked as a child psychologist and as a professor with the Department of Special Education and Rehabilitation Counseling at the University of Kentucky. He coordinated the graduate Personnel Preparation Program for Teachers…

  12. Eesti luksushotellide ristiisa / Michael Stenner ; interv. Malle Koido

    Index Scriptorium Estoniae

    Stenner, Michael

    2007-01-01

    Eesti tipphotelle 1997. aastast juhtinud sakslane, praegu hotellide Kolm Õde ja Telegraaf juht räägib Eesti ja Saksamaa erinevustest, Eesti hotelliärist, teeninduskultuurist ja personalist. Lisa: Kes on Michael Stenner ning kuidas ta Eestisse sattus? Ilmunud ka: Linnaleht : Pärnu, 23. veebr. 2007, lk. 5-6

  13. Michael Polanyi on the Education and Knowledge of Scientists.

    Science.gov (United States)

    Jacobs, Struan

    2000-01-01

    Explains why teachers addressing the nature of science should know the work of Michael Polanyi. Outlines Polanyi's intellectual career and examines his ideas on the education of scientists, research, and knowledge. Polanyi presaged Kuhn, Feyerabend, and the constructivists, yet insisted that science produces true knowledge about reality. (Contains…

  14. Michael Moore kaevati kohtusse pettuse eest / Mari Rebane

    Index Scriptorium Estoniae

    Rebane, Mari

    2006-01-01

    Dokumentaalfilm "9/11 Fahrenheiti" ("Fahrenheit 9/11") : režissöör Michael Moore : USA 2004. Iraagi sõja invaliidistunud veteran andis režissööri kohtusse teda kujutavate flmikaadrite loata ja tenentsliku kasutamise pärast

  15. SuchThatCast Episode 6: Michael Boylan

    NARCIS (Netherlands)

    Soraker, Johnny

    2012-01-01

    Michael Boylan is the John J. McDonnell jr chair in Ethics, and professor and chair of the philosophy department at Marymount University in Arlington, Virginia. In addition to being a poet and novelist, he has written more than 100 published articles and 25 books primarily in ethics, social and

  16. Berliinis võidutses Michael Haneke / Jüri Laulik

    Index Scriptorium Estoniae

    Laulik, Jüri, 1959-

    2005-01-01

    IX PÖFFil linastuv Michael Haneke film "Varjatud" ("Cache") võitis laupäeval mitu Euroopa Filmiakadeemia auhinda, sealhulgas parima filmi, parima lavastaja ja parima meesnäitleja (Daniel Auteuil) auhinna. Parima naisnäitleja tiitli pälvis Julia Jentsch ("Sophie Scholli viimased päevad"). Elutööpreemia sai sir Sean Connery

  17. Aza-Michael Reaction for an Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Nigam, Manisha; Rush, Brittney; Patel, Jay; Castillo, Raul; Dhar, Preeti

    2016-01-01

    A green, aza-Michael reaction is described that can be used to teach undergraduate students conjugate addition of nitrogen nucleophile to an a,ß-unsaturated ester. Students analyze spectral data of the product obtained from the assigned reaction to determine product structure and propose the mechanism of its formation. The experiment requires…

  18. Educational Implications of Michael Fishbane's "Sacred Attunement: A Jewish Theology"

    Science.gov (United States)

    Marom, Daniel

    2008-01-01

    This article posits Michael Fishbane's Judaic scholarship as a prime resource for Jewish education. The link between the two fields can be made through a translation of the theological underpinnings of Fishbane's insights into Judaism to educational purposes and practices. Initial work with Jewish educators on establishing this link encouraged…

  19. Correspondence of Michael Faraday, v.5 1855-1860

    CERN Document Server

    Faraday, Michael

    2008-01-01

    This volume includes 70% of previously unpublished letters of Michael Farday spanning half of the 1850s and most of 1860. Topics include Faraday's work on regelation, the transmission of light through gold and his appointment by Emperor Napoleon III to be a Commander of the Legion of Honour.

  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. Impact of Thermal Annealing on Organic Photovoltaic Cells Using Regioisomeric Donor-Acceptor-Acceptor Molecules.

    Science.gov (United States)

    Zhang, Tao; Han, Han; Zou, Yunlong; Lee, Ying-Chi; Oshima, Hiroya; Wong, Ken-Tsung; Holmes, Russell J

    2017-08-02

    We report a promising set of donor-acceptor-acceptor (D-A-A) electron-donor materials based on coplanar thieno[3,2-b]/[2,3-b]indole, benzo[c][1,2,5]thiadiazole, and dicyanovinylene, which are found to show broadband absorption with high extinction coefficients. The role of the regioisomeric electron-donating thienoindole moiety on the physical and structural properties is examined. Bulk heterojunction (BHJ) organic photovoltaic cells (OPVs) based on the thieno[2,3-b]indole-based electron donor NTU-2, using C 70 as an electron acceptor, show a champion power conversion efficiency of 5.2% under AM 1.5G solar simulated illumination. This efficiency is limited by a low fill factor (FF), as has previously been the case in D-A-A systems. In order to identify the origin of the limited FF, further insight into donor layer charge-transport behavior is realized by examining planar heterojunction OPVs, with emphasis on the evolution of film morphology with thermal annealing. Compared to as-deposited OPVs that exhibit insufficient donor crystallinity, crystalline OPVs based on annealed thin films show an increase in the short-circuit current density, FF, and power conversion efficiency. These results suggest that that the crystallization of D-A-A molecules might not be realized spontaneously at room temperature and that further processing is needed to realize efficient charge transport in these materials.

  2. Alkyl Radicals as Hydrogen Bond Acceptors: Computational Evidence

    DEFF Research Database (Denmark)

    Hammerum, Steen

    2009-01-01

    Spectroscopic, energetic and structural information obtained by DFT and G3-type computational studies demonstrates that charged proton donors can form moderately strong hydrogen bonds to simple alkyl radicals. The presence of these bonds stabilizes the adducts and modifies their structure......, 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...... acceptors than formaldehyde molecules, while propyl radicals are as good as H2O. The hydrogen bond strength appears to depend on the proton affinity of the proton donor and on the ionization energy of the acceptor alkyl radical, not on the donor-acceptor proton affinity difference, reflecting...

  3. Michael Pärt ئ suure muusika taustajõud / Michael Pärt ; interv. Siim Nestor

    Index Scriptorium Estoniae

    Pärt, Michael

    2008-01-01

    Arvo Pärdi pojast Michael Pärdist. Tema tööst "music editor"-ina - helimonteerijana, tööst muusika produktsiooni, salvestamise ja muusika kirjutamise abijõuna. Koostööst maailmas tuntud muusikutega

  4. 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.

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

    KAUST Repository

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

    2018-01-01

    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.

  6. Double Michael Addition Reaction of Bischalcone under Ultrasound

    Institute of Scientific and Technical Information of China (English)

    LI,Ji-Tai; XU,Wen-Zhi; CHEN,Guo-Feng; LI,Tong-Shuang

    2004-01-01

    @@ The Michael addition of 1,5-diaryl-1,4-pentadien-3-ones with active methylene compounds has been the subjects of many investigations. Ultrasound has increasingly been used in organic synthesis in the last three decades. Compared with traditional methods, this method is more convenient and easily controlled. A large number of organic reactions can be carried out in higher yield, shorter reaction time or milder conditions under ultrasonic irradiation. KF/Al2O3 as a useful solid supported catalyst has received considerable attention because of their high level of chemoselectivity and environmental compatibility as well as simplicity of operation and their ready availability at low cost. Herein we report the double Michael addition of dibenzalacetone with active methlene compounds such as dimethyl malonate, diethyl malonate,methyl cyanoacetate and ethyl cyanoacetate catalyzed by KF/Al2O3 under ultrasound irradiation.

  7. Asymmetric Michael Addition Mediated by Chiral Ionic Liquids

    Science.gov (United States)

    Suzuki, Yumiko

    2018-01-01

    Chiral ionic liquids with a focus on their applications in asymmetric Michael additions and related reactions were reviewed. The examples were classified on the basis of the mode of asymmetric induction (e.g., external induction/non-covalent interaction or internal induction/covalent bond formation), the roles in reactions (as a solvent or catalyst), and their structural features (e.g., imidazolium-based chiral cations, other chiral oniums; proline derivatives). Most of the reactions with high chiral induction are Michael addition of ketones or aldehydes to chalcones or nitrostyrenes where proline-derived chiral ionic liquids catalyze the reaction through enamine/ iminium formation. Many reports demonstrate the recyclability of ionic liquid-tagged pyrrolidines. PMID:29861702

  8. Asymmetric Michael Addition Mediated by Chiral Ionic Liquids.

    Science.gov (United States)

    Suzuki, Yumiko

    2018-06-01

    Chiral ionic liquids with a focus on their applications in asymmetric Michael additions and related reactions were reviewed. The examples were classified on the basis of the mode of asymmetric induction (e.g., external induction/non-covalent interaction or internal induction/covalent bond formation), the roles in reactions (as a solvent or catalyst), and their structural features (e.g., imidazolium-based chiral cations, other chiral oniums; proline derivatives). Most of the reactions with high chiral induction are Michael addition of ketones or aldehydes to chalcones or nitrostyrenes where proline-derived chiral ionic liquids catalyze the reaction through enamine/ iminium formation. Many reports demonstrate the recyclability of ionic liquid-tagged pyrrolidines.

  9. Pengaruh Tipografi pada Era Massimo Vignelli terhadap Tipografi Michael Bierut

    Directory of Open Access Journals (Sweden)

    Irwan Harnoko

    2011-10-01

    Full Text Available Massimo Vignelli is a senior graphic designer lived in New York, as a vocal modernism against post-modernism. His statement firmly opposing post-modernism in several occasions: interview in Helvetica the movie, typeradio, talkshow, and some articles in Looking Closer or AIGA Journal. Graphic design works of Massimo Vignelli reflected his characteristic, which is firmly choosing typeface. Typefaces of Vignelly are around 5 typefaces: Bodoni, Helvetica, Times Roman, Century, and Futura. The article uses formal analysis method. The writers collected materials about Michael Bierut, Massimo VIgnelli and Tibor Kalman from books and websites. The writers compare the typeface opinion of Massimo Vignelli (modernism designer, Michael Bierut designer (transition era designer from modernism to post-modernism, and Tibor Kalman (a designer in A Century of Graphic Design, as the influencer of Bierut’s betrayal over Vignelli. 

  10. Tribute to Professor Anthony J. McMichael

    Directory of Open Access Journals (Sweden)

    Ashwin Swaminathan

    2014-11-01

    Full Text Available Emeritus Professor A. J. “Tony” McMichael (1942–2014 was an internationally renowned and pioneering Australian academic and advocate in epidemiology, who was passionate about understanding the influences of the environment on human health. In an illustrious career spanning more than four decades, he made significant contributions to the scientific community and policy discourse—including ground-breaking research related to the health of children. McMichael was a prolific academic writer with over 300 peer-reviewed papers; 160 book chapters and two sole-authored books. However, his outstanding talent was for integrating complex and seemingly unrelated strands from the environmental and health sciences into a cohesive narrative—and highlighting its relevance to lay persons, scientists and governments alike. He was instrumental in validating this nascent field of research and inspiring many others to follow his lead.

  11. Political Cinema and Culture industry: the work of Michael Moore

    OpenAIRE

    Cristiane Toledo Maria

    2015-01-01

    This article aims to reflect upon the production of the American filmmaker Michael Moore, proposing as a central question the relationship established between art and politics in a historical moment which, on one side, points to the crisis of capitalism and, on the other side, to the political fragmentation of the working class. Focusing on the analysis of the documentaries Roger & Me (1989) and Capitalism: a love story (2009), this article is an attempt to understand the method developed by ...

  12. Entretien avec Michael Quinn Patton | CRDI - Centre de recherches ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    9 févr. 2011 ... Michael Quinn Patton, évaluateur de renommée internationale, était récemment au CRDI .... C'est un mode de pensée analytique qui doit tout imprégner. ... des données solides et crédibles sur ce qui marche et ce qui ne marche pas. ... des emplois, des infrastructures et un accès à la nourriture et aux mar.

  13. Euroopa parimaks filmiks sai Michael Haneke "Valge lint" / Andres Laasik

    Index Scriptorium Estoniae

    Laasik, Andres, 1960-2016

    2009-01-01

    Euroopa Filmiakadeemia auhindadest: parima filmiauhinna sai Saksamaal Bochumis toimunud tseremoonial Michael Haneke "Valge lint", mille eest Haneke sai ka parima režissööri ja stsenaristi auhinna. Parimaks meesnäitlejaks pärjati Tahar Rahim ("Un Prophete"), parimaks naisnäitlejaks Kate Winslet ("The Reader"), publikupreemia sai Danny Boyle'i "Rentslimiljonär. Ka teistest võitjatest

  14. Characteristics of ovulation method acceptors: a cross-cultural assessment.

    Science.gov (United States)

    Klaus, H; Labbok, M; Barker, D

    1988-01-01

    Five programs of instruction in the ovulation method (OM) in diverse geographic and cultural settings are described, and characteristics of approximately 200 consecutive OM acceptors in each program are examined. Major findings include: the religious background and family size of acceptors are variable, as is the level of previous contraceptive use. Acceptors are drawn from a wide range of socioeconomic and religious backgrounds; however, family planning intention was similarly distributed in all five countries. In sum, the ovulation method is accepted by persons from a variety of backgrounds within and between cultural setting.

  15. profile of intrauterine contraceptive device acceptors at the university

    African Journals Online (AJOL)

    ANNALS

    Conclusion: The acceptors of intrauterine contraceptive devices in our center were ... Conclusion: Les accepteurs de la contraception de substances médicamentenses dans notre centre .... sterilization due to cultural reasons is very low,13 the.

  16. 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...

  17. A copper-relates shallow acceptor in quenched germanium

    International Nuclear Information System (INIS)

    Kamiura, Yoichi; Hashimoto, Fumio; Sugiyama, Hazime; Yoneyama, Shin-ichiro

    1982-01-01

    The temperature variation of hole density was measured in the range 5-200 K after successive annealings at 320sup(o)C. It was found that a shallow acceptor at Esub(v) + 9 meV disappears on annealing, being replaced by a just equal additional density of substitutional copper. This provides experimental proof that the shallow acceptor is a defect complex containing at least one copper atom. (author)

  18. Fluorescent and Colorimetric Molecular Recognition Probe for Hydrogen Bond Acceptors

    OpenAIRE

    Pike, Sarah Jane; Hunter, Christopher Alexander

    2018-01-01

    The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish sel...

  19. 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.

  20. Fluorescent and colorimetric molecular recognition probe for hydrogen bond acceptors.

    Science.gov (United States)

    Pike, Sarah J; Hunter, Christopher A

    2017-11-22

    The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish self-consistent H-bond acceptor parameters (β) for benzoate, azide, chloride, thiocyanate anions, a series of phosphine oxides, phosphate ester, sulfoxide and a tertiary amide. The results demonstrate both the transferability of H-bond parameters between different solvents and the utility of the naphthol-based dual molecular recognition probe to exploit orthogonal spectroscopic techniques to determine the HBA properties of neutral and charged solutes. The benzoate anion is the strongest HBA studied with a β parameter of 15.4, and the neutral tertiary amide is the weakest H-bond acceptor investigated with a β parameter of 8.5. The H-bond acceptor strength of the azide anion is higher than that of chloride (12.8 and 12.2 respectively), and the thiocyanate anion has a β value of 10.8 and thus is a significantly weaker H-bond acceptor than both the azide and chloride anions.

  1. Cocrystals of 6-methyl-2-thiouracil: presence of the acceptor-donor-acceptor/donor-acceptor-donor synthon.

    Science.gov (United States)

    Hützler, Wilhelm Maximilian; Egert, Ernst

    2015-03-01

    The results of seven cocrystallization experiments of the antithyroid drug 6-methyl-2-thiouracil (MTU), C(5)H(6)N(2)OS, with 2,4-diaminopyrimidine, 2,4,6-triaminopyrimidine and 6-amino-3H-isocytosine (viz. 2,6-diamino-3H-pyrimidin-4-one) are reported. MTU features an ADA (A = acceptor and D = donor) hydrogen-bonding site, while the three coformers show complementary DAD hydrogen-bonding sites and therefore should be capable of forming an ADA/DAD N-H...O/N-H...N/N-H...S synthon with MTU. The experiments yielded one cocrystal and six cocrystal solvates, namely 6-methyl-2-thiouracil-2,4-diaminopyrimidine-1-methylpyrrolidin-2-one (1/1/2), C(5)H(6)N(2)OS·C(4)H(6)N(4)·2C(5)H(9)NO, (I), 6-methyl-2-thiouracil-2,4-diaminopyrimidine (1/1), C(5)H(6)N(2)OS·C(4)H(6)N(4), (II), 6-methyl-2-thiouracil-2,4-diaminopyrimidine-N,N-dimethylacetamide (2/1/2), 2C(5)H(6)N(2)OS·C(4)H(6)N(4)·2C(4)H(9)NO, (III), 6-methyl-2-thiouracil-2,4-diaminopyrimidine-N,N-dimethylformamide (2/1/2), C(5)H(6)N(2)OS·0.5C(4)H(6)N(4)·C(3)H(7)NO, (IV), 2,4,6-triaminopyrimidinium 6-methyl-2-thiouracilate-6-methyl-2-thiouracil-N,N-dimethylformamide (1/1/2), C(4)H(8)N(5)(+)·C(5)H(5)N(2)OS(-)·C(5)H(6)N(2)OS·2C(3)H(7)NO, (V), 6-methyl-2-thiouracil-6-amino-3H-isocytosine-N,N-dimethylformamide (1/1/1), C(5)H(6)N(2)OS·C(4)H(6)N(4)O·C(3)H(7)NO, (VI), and 6-methyl-2-thiouracil-6-amino-3H-isocytosine-dimethyl sulfoxide (1/1/1), C(5)H(6)N(2)OS·C(4)H(6)N(4)O·C(2)H(6)OS, (VII). Whereas in cocrystal (I) an R(2)(2)(8) interaction similar to the Watson-Crick adenine/uracil base pair is formed and a two-dimensional hydrogen-bonding network is observed, the cocrystals (II)-(VII) contain the triply hydrogen-bonded ADA/DAD N-H...O/N-H...N/N-H...S synthon and show a one-dimensional hydrogen-bonding network. Although 2,4-diaminopyrimidine possesses only one DAD hydrogen-bonding site, it is, due to orientational disorder, triply connected to two MTU molecules in (III) and (IV).

  2. 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.

  3. Michael Kohlhaas or the Germans and Their Law

    Directory of Open Access Journals (Sweden)

    Heike Jung

    2014-12-01

    Full Text Available Asked to pick a single representative ‘German’ piece for a discourse on ‘Law and Literature’ one almost inevitably ends up with Kleist’s tale Michael Kohlhaas. It seems to be the literary incarnation of the German stance vis-à-vis the law. It is all about horses; it could just as well be about dogs. Kohlhaas fights a devastating battle, using legal means and outright violence, even warfare, for their recovery in good shape. Victorious eventually with his legal actions, he is happy to trade in his own life for this victory, thus giving an extreme example for the nice line between being in the right and pursuing this position with disproportionate rigour. Of course, the interpretations of Michael Kohlhaas (which, in its complete version, dates of 1810 have varied from epoch to epoch as well as from reader to reader. It is not possible to rehearse the bulk of ‘Kohlhaas literature’. In comparing legal cultures, it might be of interest to look into the question why such a somber story on the law forms part and will continue to form part of the German cultural heritage. Si se tiene que elegir un único representante “alemán” para una ponencia sobre “derecho y literatura”, es inevitable optar por la obra de Kleist, Michael Kohlhaas. Parece la encarnación literaria de la posición alemana hacia el derecho. El libro trata de caballos; también podría tratar sobre perros. Kohlhaas libra una batalla devastadora usando medios legales y la violencia pura y dura, incluso la guerra, para que se recuperen en buena forma. Finalmente resulta ganador mediante acciones legales, está contento de dedicar su propia vida para conseguir esta victoria, dando así un ejemplo extremo de la línea que existe entre tener la razón y seguir esta posición con un rigor desproporcionado. Por supuesto, las interpretaciones de Michael Kohlhaas (publicado en 1810 han variado de una época a otra, y de un lector a otro. No es posible revisar el grueso de

  4. The Correspondence of Michael Faraday Pt 6 1860-1867

    CERN Document Server

    Frank, James

    2012-01-01

    Michael Faraday (1791-1867) was one of the most important men of science in nineteenth century Britain. His discoveries of electro-magnetic rotations (1821) and electro-magnetic induction (1831) laid the foundations of the modern electrical industry. His discovery of the magneto-optical effect and diamagnetism (1845) led him to formulate the field theory of electro-magnetism, which forms one of the cornerstones of modern physics.These and a whole host of other fundamental discoveries in physics and chemistry, together with his lecturing at the Royal Institution, his work for the state (includi

  5. Michael Marinov memorial volume multiple facets of quantization and supersymmetry

    CERN Document Server

    Vainshtein, A I

    2002-01-01

    This book is dedicated to the memory of Michael Marinov, the theorist who, together with Felix Berezin, introduced the classical description of spin by anticommuting Grassmann variables. It contains original papers and reviews by physicists and mathematicians written specifically for the book. These articles reflect the current status and recent developments in the areas of Marinov's research: quantum tunneling, quantization of constrained systems, supersymmetry, and others. The personal recollections included portray the human face of M Marinov, a person of great knowledge and integrity.

  6. 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.

  7. 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.

  8. Improving Photoconductance of Fluorinated Donors with Fluorinated Acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Garner, Logan E.; Larson, Bryon; Oosterhout, Stefan; Owczarczyk, Zbyslaw; Olson, Dana C.; Kopidakis, Nikos; Boltalina, Olga V.; Strauss, Steven H.; Braunecker, Wade A.

    2016-11-21

    This work investigates the influence of fluorination of both donor and acceptor materials on the generation of free charge carriers in small molecule donor/fullerene acceptor BHJ OPV active layers. A fluorinated and non-fluorinated small molecule analogue were synthesized and their optoelectronic properties characterized. The intrinsic photoconductance of blends of these small molecule donors was investigated using time-resolved microwave conductivity. Blends of the two donor molecules with a traditional non-fluorinated fullerene (PC70BM) as well as a fluorinated fullerene (C60(CF3)2-1) were investigated using 5% and 50% fullerene loading. We demonstrate for the first time that photoconductance in a 50:50 donor:acceptor BHJ blend using a fluorinated fullerene can actually be improved relative to a traditional non-fluorinated fullerene by fluorinating the donor molecule as well.

  9. 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

  10. A Study of Postmodern Narrative in Michael Cunningham's The Hours

    Directory of Open Access Journals (Sweden)

    Hajar Abbasi Narinabad

    2012-09-01

    Full Text Available This project aims at providing a detailed analysis of the major features of the theory of postmodern narrative and at going through the novel The Hours by the American writer Michael Cunningham concentrating on some postmodern narrative techniques. To do so, the researcher goes through the theories set forth by some postmodern theoreticians like Roland Barthes, Jacque Derrida, Jean-François Lyotard and Julia Kristeva to investigate the postmodern narrative techniques and elements used in the novel. The researcher first examines the theories and then critically applies them on the novel. The article goes through the most eminent elements of postmodern narrative including intertextuality, stream of consciousness style, fragmentation and representation respectively which are delicately utilized in The Hours. The article concludes by recommending a few directions for the further research.

  11. Michael Longley’s Father: Memory, Mourning and History

    Directory of Open Access Journals (Sweden)

    Barry Sloan

    2012-03-01

    Full Text Available Michael Longley’s father has been a recurring presence in the poet’s work from his earliest to his most recent collection. This paper examines the exceptional strength of that bond reflected in the varied and changing ways in which the poet has responded to it – memorizing and mourning his loss; discovering through his father’s First World War stories a means of memorialising loss of life in contemporary conflicts and a way of facing the history of the twentieth century; confronting his own ageing and sense of mortality; and marking the specific, but also representative, generational history of his family. Close readings of key poems are offered to highlight Longley’s skills in meeting his own exacting standards of aesthetic propriety and moral and social responsibility for writers of elegy in order to avoid either exploitation of tragedy and loss, or facile gestures of consolation.

  12. Estratégia competitiva: Michael Porter 30 anos depois

    Directory of Open Access Journals (Sweden)

    Manuel Portugal Ferreira

    2009-12-01

    Full Text Available Os estudos de estratégia têm sido muito influenciados pelos trabalhos de Michael Porter, em todas as suas fases, como as cinco forças, as estratégias genéricas, a cadeia de valor e as vantagens competitivas das nações. Neste artigo, analisou-se a influência de Porter nos trabalhos brasileiros em estratégia, a partir dos trabalhos selecionados e apresentados no EnANPAD. No levantamento para a análise dos artigos, considerando 10 anos de EnANPAD (1997-2006, foram selecionados 46 artigos. A identificação e seleção dos artigos envolveram os seguintes critérios: busca complementar por palavra-chave Porter na base de dados do EnANPAD; avaliação dos títulos e resumos dos artigos apresentados na área de estratégia entre 1997 e 2006, bem como na íntegra quando necessário. Procedeu-se também à análise das referências utilizadas nos artigos e o posicionamento dos autores em relação às tipologias de Porter. Como resultado, verificou-se que Michael Porter é um autor com grande influência nas pesquisas acadêmicas de estratégia. Seus estudos mais utilizados são os da análise da indústria e das estratégias genéricas, e também se verificou que a maioria dos estudos analisados é favorável aos seus conceitos, mesmo existindo pesquisas contrárias.

  13. 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 at t...... acceptors (e.g., nitrate, iron, copper, perchlorate) and mediators....

  14. 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...

  15. Studying Teachers and Schools: Michael Pressley's Legacy and Directions for Future Research

    Science.gov (United States)

    Mohan, Lindsey; Lundeberg, Mary A.; Reffitt, Kelly

    2008-01-01

    Much of Michael Pressley's work during the past decade focused on the nature of highly effective, engaging literacy instruction. Michael Pressley believed that studying effective teachers and schools had the potential to influence more engaging and effective teaching, especially in underresourced schools. First, we describe the grounded…

  16. Markets, Marx, Modernity and Mathematics Education: A Response to Michael Apple.

    Science.gov (United States)

    Gates, Peter

    This paper is a response to Michael Apple's paper, "What Postmodernists Forget: Cultural Capital and Official Knowledge." The paper advocates Michael's identification of the current dangers and processes of the growth of new right ideologies in the development of subjectivity, society, and education. The differences in success in the education…

  17. Reflections on Michael Hardt and Antonio Negri’s Book “Assembly”

    Directory of Open Access Journals (Sweden)

    Christian Fuchs

    2017-10-01

    Full Text Available This contribution presents reflections on Michael Hardt and Antonio Negri’s book “Assembly” (2017, Oxford: Oxford University Press, ISBN 978-0190677961. Keywords: assembly, Michael Hardt, Antonio Negri, multitude, common, entrepreneurship of the multitude, the new Prince, digital capitalism, digital assemblage, neoliberalism, finance

  18. 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....

  19. Bond of donor-acceptor interaction in metal-ligand system with energies of Fermi electrons

    International Nuclear Information System (INIS)

    Vlasov, Yu.V.; Khentov, V.Ya.; Velikanova, L.N.; Semchenko, V.V.

    1993-01-01

    Role of quantum nature of metal (W, Mo and others) in donor-acceptor interaction of metal salicylalaniline - aprotic solvent was discussed. The dependence of dissolution rate and activation energy of donor-acceptor interaction on electron energy was established

  20. 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

    Positron lifetime measurements were performed on a series of organic electron acceptors and charge-transfer complexes in solution. The acceptors cause both positronium (Ps) inhibition (with maybe one exception) and quenching, but when an acceptor takes part in a charge-transfer complex...... in terms of the spur reaction model of Ps formation. Correlation was also made to gas phase reaction between electron acceptors and free electron, as well as to pulse radiolysis data....

  1. 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.

  2. Effect of anneal and quench on the nature of the dominant acceptors in ZnTe

    International Nuclear Information System (INIS)

    Bensahel, D.; Magnea, N.; Pautrat, J.L.; Pfister, J.C.; Revoil, L.

    1978-01-01

    Anneal and quench studies on high purity ZnTe have shown the dominant role of impurities and their solubilities as functions of stoichiometrical conditions. The role of 'b' acceptor, related to lithium, 'g' acceptor, related to silver, and 'a' acceptor of unknown nature is reported

  3. Michael Field’s “A Dance of Death”

    Directory of Open Access Journals (Sweden)

    LeeAnne Richardson

    2012-03-01

    Full Text Available The 1912 poem "A Dance of Death" by Michael Field (pen name of Katherine Bradley and her niece Edith Cooper depicts Salome in an alternate version of the biblical story: this Salome dances on a frozen river, falls through the ice, and is decapitated on a jagged edge. Nonetheless, her beautiful head continues dancing over the frozen river. This poem is highly unusual, especially in the context of the other poems in the postconversion volume Poems of Adoration, because it questions, rather than submits to, authority. In re-writing a familiar Christian tale, as well as a familiar decadent theme, Field uses the poem to assert the supremacy of their artistic vision, which (despite their ardent Catholicism cannot be subject to any law outside themselves. Like the continually dancing head of Salome, which continues to create beauty even after nature (and perhaps God has struck it down, the poet is subjugate only to her own law and creates without boundaries or restrictions on her art. Bradley and Cooper were acutely aware of their authorial persona (actively taking not only a masculine but also a singular poetic identity, and their mode of reconciling the apparent contradictions of this identity are mirrored in their presentation of Salome in a "Dance of Death."

  4. A Musical Italy: Michael W. Balfe’s Italian Experiences

    Directory of Open Access Journals (Sweden)

    Basil Walsh

    2016-06-01

    Full Text Available The Dublin-born musician, Michael W. Balfe, was a singer, composerand conductor whose brilliant musical career was heavily influenced byformative experiences in Italy. In 1825, Balfe, interested in broadeninghis musical studies first went to Paris where he was introduced to thegreat composers, Luigi Cherubini and Gioachino Rossini, who took apersonal interest in him and his musical talents. On the advice of Rossinihe spent the next few years in Italy studying singing with the famousRossini singer, Filippo Galli, and taking music composition lessonsfrom Ferdinando Paer, in Rome. Later in Milan he studied harmonyand counterpoint with Vincenzo Federici. By 1831, when he was only23 years old, his first three operas had been produced in Palermo, Pavia,and Milan. He returned to London in August 1835, participatingwith the great Lablache, Tamburini, Rubini and Grisi in a concert inVauxhall Gardens. In 1834 he made his debut at La Scala, Milan, singingopposite the renowned mezzo-soprano, Maria Malibran in Rossini’sOtello. He appeared again with Malibran in Venice early in 1835,singing once more in Rossini and Bellini operas. Balfe worked as a singerand composer throughout the Italian peninsula/states during the years,1825-1835 and this article will chart these experiences and demonstratehow the time he spent in Italy and the people he met, influenced hislife and later career as an important and popular European composer.

  5. 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.

  6. Interface effects on acceptor qubits in silicon and germanium

    International Nuclear Information System (INIS)

    Abadillo-Uriel, J C; Calderón, M J

    2016-01-01

    Dopant-based quantum computing implementations often require the dopants to be situated close to an interface to facilitate qubit manipulation with local gates. Interfaces not only modify the energies of the bound states but also affect their symmetry. Making use of the successful effective mass theory we study the energy spectra of acceptors in Si or Ge taking into account the quantum confinement, the dielectric mismatch and the central cell effects. The presence of an interface puts constraints to the allowed symmetries and leads to the splitting of the ground state in two Kramers doublets (Mol et al 2015 Appl. Phys. Lett. 106 203110). Inversion symmetry breaking also implies parity mixing which affects the allowed optical transitions. Consequences for acceptor qubits are discussed. (paper)

  7. Positively charged phosphorus as a hydrogen bond acceptor

    DEFF Research Database (Denmark)

    Hansen, Anne Schou; Du, Lin; Kjærgaard, Henrik Grum

    2014-01-01

    Phosphorus (P) is an element that is essential to the life of all organisms, and the atmospheric detection of phosphine suggests the existence of a volatile biogeochemical P cycle. Here, we investigate the ability of P to participate in the formation of OH···P hydrogen bonds. Three bimolecular......-stretching frequency red shifts and quantum chemical calculations, we find that P is an acceptor atom similar in strength to O and S and that all three P, O, and S atoms are weaker acceptors than N. The quantum chemical calculations show that both H and P in the OH···P hydrogen bond have partial positive charges......, as expected from their electronegativities. However, the electrostatic potentials show a negative potential area on the electron density surface around P that facilitates formation of hydrogen bonds....

  8. Triplet Tellurophene-Based Acceptors for Organic Solar Cells.

    Science.gov (United States)

    Yang, Lei; Gu, Wenxing; Lv, Lei; Chen, Yusheng; Yang, Yufei; Ye, Pan; Wu, Jianfei; Hong, Ling; Peng, Aidong; Huang, Hui

    2018-01-22

    Triplet materials have been employed to achieve high-performing organic solar cells (OSCs) by extending the exciton lifetime and diffusion distances, while the triplet non-fullerene acceptor materials have never been reported for bulk heterojunction OSCs. Herein, for the first time, three triplet molecular acceptors based on tellurophene with different degrees of ring fusing were designed and synthesized for OSCs. Significantly, these molecules have long exciton lifetime and diffusion lengths, leading to efficient power conversion efficiency (7.52 %), which is the highest value for tellurophene-based OSCs. The influence of the extent of ring fusing on molecular geometry and OSCs performance was investigated to show the power conversion efficiencies (PCEs) continuously increased along with increasing the extent of ring fusing. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Polymer solar cells with novel fullerene-based acceptor

    International Nuclear Information System (INIS)

    Riedel, I.; Martin, N.; Giacalone, F.; Segura, J.L.; Chirvase, D.; Parisi, J.; Dyakonov, V.

    2004-01-01

    Alternative acceptor materials are possible candidates to improve the optical absorption and/or the open circuit voltage of polymer-fullerene solar cells. We studied a novel fullerene-type acceptor, DPM-12, for application in polymer-fullerene bulk heterojunction photovoltaic devices. Though DPM-12 has the identical redox potentials as methanofullerene PCBM, surprisingly high open circuit voltages in the range V OC =0.95 V were measured for OC 1 C 10 -PPV:DPM-12-based samples. The potential for photovoltaic application was studied by means of photovoltaic characterization of solar cells including current-voltage measurements and external quantum yield spectroscopy. Further studies were carried out by profiling the solar cell parameters vs. temperature and white light intensity

  10. 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.

  11. Selection of electron acceptors and strategies for in situ bioremediation

    International Nuclear Information System (INIS)

    Norris, R.D.

    1995-01-01

    The most critical aspect of designing in situ bioremediation systems is, typically, the selection and method of delivery of the electron acceptor. Nitrate, sulfate, and several forms of oxygen can be introduced, depending on the contaminants and the site conditions. Oxygen can be added as air, pure oxygen, hydrogen peroxide, or an oxygen release compound. Simplistic cost calculations can illustrate the advantages of some methods over others, providing technical requirements can be met

  12. 75 FR 62635 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...

    Science.gov (United States)

    2010-10-12

    ... Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program) Activity: Comment Request... determine patients' satisfaction with services provided by or through the Michael E. DeBakey Home Care...: Patient Satisfaction Survey Michael E. DeBakey Home Care Program, VA Form 10-0476. OMB Control Number...

  13. 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.

  14. 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.

  15. 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.

  16. Virtual screening of electron acceptor materials for organic photovoltaic applications

    International Nuclear Information System (INIS)

    D Halls, Mathew; Giesen, David J; Goldberg, Alexander; Djurovich, Peter J; Sommer, Jonathan; McAnally, Eric; Thompson, Mark E

    2013-01-01

    Virtual screening involves the generation of structure libraries, automated analysis to predict properties related to application performance and subsequent screening to identify lead systems and estimate critical structure–property limits across a targeted chemical design space. This approach holds great promise for informing experimental discovery and development efforts for next-generation materials, such as organic semiconductors. In this work, the virtual screening approach is illustrated for nitrogen-substituted pentacene molecules to identify systems for development as electron acceptor materials for use in organic photovoltaic (OPV) devices. A structure library of tetra-azapentacenes (TAPs) was generated by substituting four nitrogens for CH at 12 sites on the pentacene molecular framework. Molecular properties (e.g. E LUMO , E g and μ) were computed for each candidate structure using hybrid DFT at the B3LYP/6-311G** level of theory. The resulting TAPs library was then analyzed with respect to intrinsic properties associated with OPV acceptor performance. Marcus reorganization energies for charge transport for the most favorable TAP candidates were then calculated to further determine suitability as OPV electron acceptors. The synthesis, characterization and OPV device testing of TAP materials is underway, guided by these results. (paper)

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. Theory and practice in action: the contributions of Michael Perkins to clinical linguistics.

    Science.gov (United States)

    Damico, Jack S; Lynch, Karen E

    2013-01-01

    This article reviews the scholarly contributions of Michael R. Perkins in the discipline of clinical linguistics and provides some indication of the reasons that he has been so successful. Three primary attributes were described through an analysis of his publications.

  3. Tõsine fotoelamus Dubrovnikus / Wade Goddard, Heidi Levine, Michael Robinson Chaver ; interv. Ahto Külvet

    Index Scriptorium Estoniae

    Goddard, Wade

    2007-01-01

    Dubrovniku vanalinnas asub Sõjafotokeskus. Intervjuu keskuse asutaja, kanadalasest fotograafi Wade Goddardi ja kahe seal augustis avatud näitusel osalenud fotograafi Heidi Levine'i ja Michael Robinson Chavez'iga. Sõjafotograafi tööst

  4. Joseph and Michael Haydn in the Bohemian music archives. An anniversary tribute

    Czech Academy of Sciences Publication Activity Database

    Freemanová, Michaela

    2012-01-01

    Roč. 20, č. 1 (2012), s. 117-126. ISBN 978-3-486-58949-8. ISSN 1865-5696 Institutional support: RVO:68378076 Keywords : Joseph Haydn * Michael Haydn * music archives Subject RIV: AL - Art, Architecture, Cultural Heritage

  5. Chiral Aminophosphines as Catalysts for Enantioselective Double-Michael Indoline Syntheses

    Directory of Open Access Journals (Sweden)

    Ohyun Kwon

    2012-05-01

    Full Text Available The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogen-containing heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant of the reaction were to be developed. Aminophosphines can also facilitate the double-Michael reaction and chiral amines are more readily available in Nature and synthetically; therefore, in this study we prepared several new chiral aminophosphines. When employed in the asymmetric double-Michael reaction between ortho-tosylamidophenyl malonate and 3-butyn-2-one, the chiral aminophosphines produced indolines in excellent yields with moderate asymmetric induction.

  6. Arenethiolatecopper(I) complexes as homogeneous catalysts for Michael addition reactions

    NARCIS (Netherlands)

    Koten, G. van; Klaveren, M. van; Lambert, F.; Eijkelkamp, D.J.F.M.; Grove, D.M.

    1994-01-01

    Arenethiolatocopper(I) complexes are shown to be efficient homogeneous catalysts in Michael addition reactions of several Grignard reagents to acyclic enones; the addition products are formed with excellent chemoselectivity (>99%) and good enantioselectivity (76% e.e.).

  7. Hexafluorobenzene: A powerful solvent for a noncovalent stereoselective organocatalytic Michael addition reaction

    KAUST Repository

    Lattanzi, Alessandra; De Fusco, Claudia; Russo, Alessio; Poater, Albert; Cavallo, Luigi

    2012-01-01

    A dramatic enhancement of the diastereo- and enantioselectivity in the nitro-Michael addition reaction organocatalysed by a commercially available α,α-l-diaryl prolinol was disclosed when performing the reaction in unconventional hexafluorobenzene

  8. Eesti disain on kõva, ent see tuleb moondada ekspordiks / Michael Thomson ; interv. Urmas Oja

    Index Scriptorium Estoniae

    Thomson, Michael

    2008-01-01

    Euroopa Disainiassotsiatsioonide Liidu presidendi ja Tallinnas toimunud festivali Disainiöö Eesti disainiauhinna Bruno žürii juhi Michael Thomsoni arvamus eesti disainist ning disainipoliitika vajalikkusest Eestis. Auhinnasaajate nimekiri

  9. Reports of the working groups / Eino Tamm, Sahlin Michael, Valve Kirsipuu...[jt.

    Index Scriptorium Estoniae

    1999-01-01

    Töögruppide "EU enlargement and relevant institutional reforms" (juhatajad Eino Tamm, Michael Sahlin) ja "Maintaining of competitiveness of Estonia and other candidate countries" (juhatajad Valve Kirsipuu, Terry Calbom) tööst. Autor: Reformierakond

  10. Michael Bloomberg ähvardab USA valimised "ära rikkuda" / Heiki Suurkask

    Index Scriptorium Estoniae

    Suurkask, Heiki, 1972-

    2008-01-01

    New Yorgi praegune linnapea Michael Bloomberg võib kolmanda kandidaadina sekkuda presidendikandidaatide valimiskampaaniasse, probleem on aga tema vähene tuntus. Lisa: Seni on riigipeakoha jaganud kaks suurparteid

  11. Prints Charles ja prints Michael külastasid Tallinna kirikuid / Allan Tammiku

    Index Scriptorium Estoniae

    Tammiku, Allan

    2001-01-01

    Prints Charles külastas 6. novembril Eesti-visiidi ajal Tallinna toomkirikut ja Pühavaimu kirikut, prints Michael viibis Tallinnas 11. novembril eravisiidil, ta külastas toomkirikut, Niguliste ja Pühavaimu kirikut

  12. Chinese Middle Classes: Taiwan, Hong Kong, Macao and China. Edited by Hsin-Huang Michael Hsiao

    DEFF Research Database (Denmark)

    Brødsgaard, Kjeld Erik

    2018-01-01

    Book review of: Chinese Middle Classes:Taiwan, Hong Kong, Macao and China. Edited by Hsin-Huang Michael Hsiao. Abingdon: Routledge, 2014. Pp. 268. ISBN 10: 1138120847; ISBN 13: 978-1138120846......Book review of: Chinese Middle Classes:Taiwan, Hong Kong, Macao and China. Edited by Hsin-Huang Michael Hsiao. Abingdon: Routledge, 2014. Pp. 268. ISBN 10: 1138120847; ISBN 13: 978-1138120846...

  13. 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

  14. Electrolytic formation of technetium complexes with π-acceptor ligands

    International Nuclear Information System (INIS)

    Cerda, F.; Kremer, C.; Gambino, D.; Kremer, E.

    1994-01-01

    Electrolytic reduction of pertechnetate was performed in aqueous solution containing π-acceptor ligands. Cyanide and 1,10-phenanthroline were the selected ligands. In both cases, electrolyses produced a cathodic TcO 2 deposit and soluble Tc complexes. When cyanide was the ligand, the complexes formed were [Tc(CN) 6 ] 5- and [TcO 2 (CN) 4 ] 3- . When working with the amine, [Tc(phen) 3 ] 2+ and another positively charged species were found after reaction. Results are compared with previous studies with amines, and the usefulness of the electrolytic route to obtain Tc complexes is evaluated. (author) 11 refs.; 2 figs.; 1 tab

  15. Acceptors in ZnO nanocrystals: A reinterpretation

    Science.gov (United States)

    Gehlhoff, W.; Hoffmann, A.

    2012-12-01

    In a recent article, Teklemichael et al. reported on the identification of an uncompensated acceptor in ZnO nanocrystals using infrared spectroscopy and electron paramagnetic resonance (EPR) in the dark and under illumination. Most of their conclusions, interpretations, and suggestions turned out to be erroneous. The observed EPR signals were interpreted to originate from axial and nonaxial VZn-H defects. We show that the given interpretation of the EPR results is based on misinterpretations of EPR spectra arising from defects in nanocrystals. The explanation of the infrared absorption lines is in conflict with recent results of valence band ordering and valence band splitting.

  16. 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 use as electron-accepting materials. The small molecules showed good thermal stability up to 300°C. BHJ-OSCs with SM-1 and 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.

  17. 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.

  18. Phosphorus acceptor doped ZnO nanowires prepared by pulsed-laser deposition

    International Nuclear Information System (INIS)

    Cao, B Q; Lorenz, M; Rahm, A; Wenckstern, H von; Czekalla, C; Lenzner, J; Benndorf, G; Grundmann, M

    2007-01-01

    Phosphorus-doped ZnO (ZnO:P) nanowires were successfully prepared by a novel high-pressure pulsed-laser deposition process using phosphorus pentoxide as the dopant source. Detailed cathodoluminescence studies of single ZnO:P nanowires revealed characteristic phosphorus acceptor-related peaks: neutral acceptor-bound exciton emission (A 0 , X, 3.356 eV), free-to-neutral-acceptor emission (e, A 0 , 3.314 eV), and donor-to-acceptor pair emission (DAP, ∼3.24 and ∼3.04 eV). This means that stable acceptor levels with a binding energy of about 122 meV have been induced in the nanowires by phosphorus doping. Moreover, the induced acceptors are distributed homogeneously along the doped nanowires

  19. 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.

  20. Some experiments on the primary electron acceptor in reaction centres from Rhodopseudomanas sphaeroides

    Energy Technology Data Exchange (ETDEWEB)

    Wraight, C A; Cogdell, R J; Clayton, R K

    1975-01-01

    The bacterial reaction center absorbance change at 450 nm (A-450), assigned to an anionic semiquinone, has been suggested as a candidate for the reduced form of the primary electron acceptor in bacterial photosynthesis. In reaction centers of Rhodopseudomonas sphaeroides we have found kinetic discrepancies between the decay of A-450 and the recovery of photochemical competence. In addition, no proton uptake is measurable on the first turnover, although subsequent ones elicit one proton bound per electron. These results are taken to indicate that the acceptor reaction after a long dark period may be different for the first turnover than for subsequent ones. It is suggested that A-450 is still a likely candidate for the acceptor function but that in reaction centers, additional quinone may act as an adventitious primary acceptor when the ''true'' primary acceptor is reduced. Alternatively, the primary acceptor may act in a ''ping-pong'' fashion with respect to subsequent photoelectrons.

  1. Deactivation of group III acceptors in silicon during keV electron irradiation

    International Nuclear Information System (INIS)

    Sah, C.; Sun, J.Y.; Tzou, J.J.; Pan, S.C.

    1983-01-01

    Experimental results on p-Si metal-oxide-semiconductor capacitors (MOSC's) are presented which demonstrate the electrical deactivation of the acceptor dopant impurity during 8-keV electron irradiation not only in boron but also aluminum and indium-doped silicon. The deactivation rates of the acceptors during the 8-keV electron irradiation are nearly independent of the acceptor impurity type. The final density of the remaining active acceptor approaches nonzero values N/sub infinity/, with N/sub infinity/(B) Al--H>In-H. These deactivation results are consistent with our hydrogen bond model. The thermal annealing or regeneration rate of the deactivated acceptors in the MOSC's irradiated by 8-keV electron is much smaller than that in the MOSC's that have undergone avalanche electron injection, indicating that the keV electron irradiation gives rise to stronger hydrogen-acceptor bond

  2. Absorption from Neutral Acceptors in GaAs and GaP

    DEFF Research Database (Denmark)

    Christensen, Ove

    1973-01-01

    We present a new calculation of the absorption due to transitions of holes between neutral acceptors and the various valence-band sublevels in GaAs and GaP. The acceptor wave function was approximated by a previously suggested expression for ground-state wave functions appropriate to complicated...... band extrema. Numerical calculations of the absorption from intervalence-band transitions of free holes and neutral acceptors have been performed. Good agreement with experimental results is obtained....

  3. Recent advances in photoinduced donor/acceptor copolymerization

    International Nuclear Information System (INIS)

    Joensson, S.; Viswanathan, K.; Hoyle, C.E.; Clark, S.C.; Miller, C.; Morel, F.; Decker, C.

    1999-01-01

    Photoinitiated free radical polymerization of donor (D)/acceptor (A) type monomers has gained considerable interest due to the possibility to efficiently photopolymerize non-acrylate based systems. Furthermore, this photoinduced alternating copolymerization can be accomplished without the presence of a conventional free radical generating photoinitiator. In the past, we have shown that the structural influences in the direct photolysis of N-Alkyl and N-Arylmaleimides as well as their corresponding ground state charge transfer complexes (CTC) with suitable donors have carefully been investigated. For certain combinations of A and D type monomers, a direct photolysis of the ground state complex or the excitation of the acceptor, followed by the formation of an exciplex, has been shown to initiate the copolymerization. Herein, we show that the main route of initiation is based on inter or intra molecular H-abstraction from an excited state maleimide, whereby no exciplex formation takes place. H-abstraction will predominantly take place in systems where easily abstractable hydrogens are present. Our laser flash photolysis investigation, ESR (A. Hiroshi, I. Takasi, T. Nosi, Macromol. Chem. 190 (1989) 2821) and phosphorescence emissions (K.S. Chen, T. Foster, J.K.S. Wan, J. Phys. Chem. 84 (1980) 2473; C.J. Seliskar, S.P. McGlynn, J. Chem. Phys. 55 (1971) 4337) studies show that triplet excited states of N-alkyl substituted maleimides (RMI), which are well known strong precursors for direct H-abstractions from aliphatic ethers and secondary alcohols, are formed upon excitation. Rates of copolymerization and degrees of conversion for copolymerization of maleimide/vinyl ether pairs in air and nitrogen have been measured as a function of hydrogen abstractability of the excited triplet state MI as well as the influence of concentration and hydrogen donating effect of the hydrogen donor

  4. 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 (Actinobacteria when compared to bulk soil. Electrodes as TEAs enhance electrogenic bacteria recovery and culturing. The use of MECs for the productions of Feammox-bacteria eliminates the dependence of Fe, a finite electron acceptor, therefore, allowing for continuous NH4+ removal. Finally, Fe-free Feammox-bacteria can be applied to reduce other metals of environmental concern; therefore, opening the range of possible application of Feammox-bacteria.

  5. 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

  6. Michael Goodsite gæsteprofessor på Thunderbird School of Global Management

    DEFF Research Database (Denmark)

    Pedersen, Jens Christian

    2010-01-01

    Professor Michael Goodsite er blevet udnævnt til "Visiting Professor of Global Processes and Senior Research Fellow in Climate Strategy" ved Thunderbird School of Global Management, som har verdens højst rangerede MBA uddannelse inden for international handel.......Professor Michael Goodsite er blevet udnævnt til "Visiting Professor of Global Processes and Senior Research Fellow in Climate Strategy" ved Thunderbird School of Global Management, som har verdens højst rangerede MBA uddannelse inden for international handel....

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

    KAUST Repository

    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.

    2017-01-01

    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

  8. Developments in the chemistry and band gap engineering of donor-acceptor substituted conjugated polymers

    NARCIS (Netherlands)

    Mullekom, van H.A.M.; Vekemans, J.A.J.M.; Havinga, E.E.; Meijer, E.W.

    2001-01-01

    This paper reviews the tools to manipulate and minimize the band gap of conjugated (co)polymers. The effects of minimization of the bond length alternation and of the incorporation of donor-K-acceptor units are discussed in particular. A systematic study of a series of alternating donor-acceptor

  9. Conformational dynamics of semiflexibly bridged electron donor-acceptor systems comprising long aliphatic tails

    NARCIS (Netherlands)

    Bleisteiner, B.; Marian, T.; Schneider, S.; Brouwer, A.M.; Verhoeven, J.W.

    2001-01-01

    In continuation of our previous work on the conformational dynamics (harpooning mechanism) of semiflexibly bridged electron donor-acceptor systems we have studied a derivative with two long aliphatic chains tethered to the donor and acceptor moieties, respectively. The fitting of the time- and

  10. New donor-acceptor-donor molecules based on quinoline acceptor unit with Schiff base bridge: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kotowicz, Sonia [Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice (Poland); Siwy, Mariola [Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 M. Curie-Sklodowska Str., 41-819 Zabrze (Poland); Filapek, Michal; Malecki, Jan G. [Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice (Poland); Smolarek, Karolina; Grzelak, Justyna; Mackowski, Sebastian [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, 5 Grudziadzka Str., 87-100 Torun (Poland); Slodek, Aneta, E-mail: aneta.slodek@us.edu.pl [Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice (Poland); Schab-Balcerzak, Ewa, E-mail: ewa.schab-balcerzak@us.edu.pl [Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice (Poland); Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 M. Curie-Sklodowska Str., 41-819 Zabrze (Poland)

    2017-03-15

    Three solution-processable small organic molecules bearing quinoline as electron-accepting moiety were synthesized via condensation reaction of novel 6-amino-2-(2,2’-bithiophen-5-yl)-4-phenylquinoline with 2,2’-bithiophene-5-carboxaldehyde, 9-ethyl-9H-carbazole-3-carbaldehyde and 9-phenanthrenecarboxaldehyde. The presence of alternating electron-donating and accepting units results in a donor-acceptor-donor architecture of these molecular systems. Thermal, photophysical, and electrochemical properties of these small molecules were examined and the experimental results were supported by the density functional theory calculations. The obtained molecular systems exhibited high thermal stability with decomposition temperatures (5% weight loss) exceeding 330 °C in nitrogen atmosphere. It was found, based on DSC measurements, that investigated Schiff bases form amorphous material with glass transition temperatures between 88 and 190 °C. They also showed a UV–vis absorption in the range of 250–500 nm both in solution and in solid state as film and blend with PMMA and PVK. Photoluminescence measurements revealed moderately strong blue-light emission of the imines in solution as well as in PMMA blend with quantum yields in the range of 2–26%. In the case of imines dispersed in PVK matrix the emission of green light was mainly observed. In addition, when mixed with plasmonically active silver nanowires, the compounds exhibit relatively strong electroluminescence signal, associated with plasmonics enhancement, as evidenced by high-resolution photoluminescence imaging. The energy band gap estimated based on cyclic voltammetry was between 2.38 and 2.61 eV. - Highlights: • New Schiff bases possess donor-acceptor-imine-bridge-donor architecture were synthesized and examined. • Thorough characterization of optical and electrochemical properties of novel Schiff bases has been carried out. • Optical and electrochemical measurements were compared with DFT

  11. Asymmetric organocatalytic Michael addition of Meldrum's acid to nitroalkenes: probing the mechanism of bifunctional thiourea organocatalysts

    OpenAIRE

    Kataja, Antti O.; Koskinen, Ari M.P.

    2010-01-01

    The asymmetric Michael addition of Meldrum’s acid to nitroalkenes was studied using a novel type of Cinchona alkaloid-based bifunctional thiourea organocatalyst. The functionality of the thiourea catalysts was also probed by preparing and testing thiourea-N-methylated analogues of the well-known bis-(3,5-trifluoromethyl)phenyl-substituted catalyst. Peer reviewed

  12. Passings to note: Paul Michael Packman, MD; S. Charles Schulz, MD.

    Science.gov (United States)

    Black, Donald W

    2018-02-01

    One of the keys to the success of Annals of Clinical Psychiatry has always been the tireless efforts of our dedicated Editorial Board. We recently lost 2 longtime Editorial Board members, Drs. Paul Michael Packman and S. Charles Schulz. Both will be greatly missed.

  13. Michael Perelman: An ecological future in view of Marxist Economics (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Ren Xiaomei

    2009-01-01

    @@ Interviewee profile: Michael Perelman, currently professor of Economics Department of California State University, USA, American economist and economic historian with nearly 20 publications in the field of economics criticism, including Railroading Economics, Manufacturing Discontent, The Perverse Economy, and The Invention of Capitalism.

  14. Wolff-Michael Roth's passibility: at the limits of the constructivist metaphor: a book review

    Science.gov (United States)

    Brendel, Michelle

    2014-12-01

    Wolff-Michael Roth deconstructs the preeminent role conceded to constructivism in Science Education and demonstrates how we learn and know through pain, suffering, love or passion. This review explores his book "Passibility: At the Limits of the Constructivist Metaphor" through the eyes of an outsider to the world of science education.

  15. Assessment of lipid profile of a group of undergraduates in Michael ...

    African Journals Online (AJOL)

    Objective: The aim of this study was to measure the lipid fractions in serum blood samples of apparently healthy undergraduates of Michael Okpara University of Agriculture, Umudike. Methods: A total of one hundred consenting males and females aged between 19-30 years were purposively selected from the ...

  16. Highly Functionalized Cyclopentane Derivatives by Tandem Michael Addition/Radical Cyclization/Oxygenation Reactions

    Czech Academy of Sciences Publication Activity Database

    Holan, Martin; Pohl, Radek; Císařová, I.; Klepetářová, Blanka; Jones, P. G.; Jahn, Ullrich

    2015-01-01

    Roč. 21, č. 27 (2015), s. 9877-9888 ISSN 0947-6539 R&D Projects: GA ČR GA13-40188S Institutional support: RVO:61388963 Keywords : cyclization * domino reactions * electron transfer * Michael addition * radical reactions Subject RIV: CC - Organic Chemistry Impact factor: 5.771, year: 2015

  17. Hexafluorobenzene: A powerful solvent for a noncovalent stereoselective organocatalytic Michael addition reaction

    KAUST Repository

    Lattanzi, Alessandra

    2012-01-01

    A dramatic enhancement of the diastereo- and enantioselectivity in the nitro-Michael addition reaction organocatalysed by a commercially available α,α-l-diaryl prolinol was disclosed when performing the reaction in unconventional hexafluorobenzene as a medium. DFT calculations were performed to clarify the origin of stereoselectivity and the role of C 6F 6. © The Royal Society of Chemistry 2012.

  18. Briti ekspert : euroliidus kaob Eestist tööpuudus / Michael Richardson ; interv. Airi Ilisson

    Index Scriptorium Estoniae

    Richardson, Michael

    2003-01-01

    Eestis Suurbritannia tööreformi tutvustava töö- ja sotsiaalnõuniku sõnul on Suurbritannias peaaegu kadunud pikaajaline töötus noorte hulgas, vanematest inimestest on vaid üksikud tööta kauem kui aasta. Vt. samas: Kes on Michael Richardson?

  19. Moral Education and Education in Altruism: Two Replies to Michael Hand

    Science.gov (United States)

    White, John

    2016-01-01

    This article is a critical discussion of two recent papers by Michael Hand on moral education. The first is his "Towards a Theory of Moral Education", published in the "Journal of Philosophy of Education" in 2014 (Volume 48, Issue 4). The second is a chapter called "Beyond Moral Education?" in an edited book of new…

  20. Recollections of Jack Michael and the Application of Skinner's Analysis of Verbal Behavior

    Science.gov (United States)

    Sundberg, Mark L.

    2017-01-01

    Jack Michael offered a course on verbal behavior almost every year throughout his teaching career. Jack was also interested in the application of Skinner's work and in 1976 began to offer a graduate course at Western Michigan University titled Verbal Behavior Applications. Jack and his students pursued the application of Skinner's work on verbal…

  1. From Gouldner to Gramsci: The Making of Michael Apple's "Ideology and Curriculum"

    Science.gov (United States)

    Gottesman, Isaac

    2012-01-01

    Michael Apple's "Ideology and Curriculum", published in 1979, helped initiate a broad turn in the field of education in the United States to Marxist thought as a lens through which to analyze the relationship between school and society. This classic text continues to inform scholarship in the field. While "Ideology" has…

  2. Outside in America: George Michael's music video, public sex and global pop culture

    NARCIS (Netherlands)

    Kooijman, J.

    2004-01-01

    Six months after his controversial arrest for ‘lewd conduct’ at a men’s public restroom in Beverly Hills, British pop star George Michael released the song and music video ‘Outside’ which can be seen as an explicit commentary on the controversy. In this article, I read the music video in three ways:

  3. Tandem Michael addition/radical cyclizations for the construction of highly functionalized cyclopentanes

    Czech Academy of Sciences Publication Activity Database

    Holan, Martin; Pohl, Radek; Císarová, I.; Jahn, Ullrich

    2012-01-01

    Roč. 106, - (2012), s1298-s1298 ISSN 0009-2770. [EuCheMS Chemistry Congress /4./. 26.08.2012-30.08.2012, Prague] Institutional research plan: CEZ:AV0Z40550506 Keywords : cyclization * diastereoselectivity * Michael addiction * radical reactions * domino reactions Subject RIV: CC - Organic Chemistry

  4. "Raising Standards" or Reducing Aspirations and Opportunities Still Further? Michael Gove and Examination Reforms

    Science.gov (United States)

    Allen, Martin

    2013-01-01

    Well before the examinations grade crisis of 2012, Michael Gove had set out clear intentions for reforming public examinations. Though he claimed to be improving examinations and assessment by replicating practices that took place in high-performing countries and thus improving the ability of the UK economy to "compete", this…

  5. The Educational Philosophies of Mordecai Kaplan and Michael Rosenak: Surprising Similarities and Illuminating Differences

    Science.gov (United States)

    Schein, Jeffrey; Caplan, Eric

    2014-01-01

    The thoughts of Mordecai Kaplan and Michael Rosenak present surprising commonalities as well as illuminating differences. Similarities include the perception that Judaism and Jewish education are in crisis, the belief that Jewish peoplehood must include commitment to meaningful content, the need for teachers to teach from a position of…

  6. Astronaut C. Michael Foale is briefed on use of Sky Genie

    Science.gov (United States)

    1994-01-01

    Astronaut C. Michael Foale, STS-63 mission specialist, is briefed on the use of Sky Genie device by Karin L. Porter. The device would aid in emergency egress operations aboard a troubled Space Shuttle. Porter, an employee of Rockwell International, helps train astronauts in egress procedures at JSC's Shuttle mockup and integration laboratory.

  7. Gender Relations and Sexual Harassment in the Workplace: Michael Crichton's "Disclosure" as a Teaching Tool.

    Science.gov (United States)

    Comer, Debra R.; Cooper, Elizabeth A.

    1998-01-01

    Describes how to use Michael Crichton's novel "Disclosure" and the film based on it for class discussions of such issues as what constitutes sexual harassment, harassment of men, relationship between sexual harassment and power, organizational responses to harassment, and gender differences in career advancement tactics. (SK)

  8. The power of virtual integration: an interview with Dell Computer's Michael Dell. Interview by Joan Magretta.

    Science.gov (United States)

    Dell, M

    1998-01-01

    Michael Dell started his computer company in 1984 with a simple business insight. He could bypass the dealer channel through which personal computers were then being sold and sell directly to customers, building products to order. Dell's direct model eliminated the dealer's markup and the risks associated with carrying large inventories of finished goods. In this interview, Michael Dell provides a detailed description of how his company is pushing that business model one step further, toward what he calls virtual integration. Dell is using technology and information to blur the traditional boundaries in the value chain between suppliers, manufacturers, and customers. The individual pieces of Dell's strategy--customer focus, supplier partnerships, mass customization, just-in-time manufacturing--may be all be familiar. But Michael Dell's business insight into how to combine them is highly innovative. Direct relationships with customers create valuable information, which in turn allows the company to coordinate its entire value chain back through manufacturing to product design. Dell describes how his company has come to achieve this tight coordination without the "drag effect" of ownership. Dell reaps the advantages of being vertically integrated without incurring the costs, all the while achieving the focus, agility, and speed of a virtual organization. As envisioned by Michael Dell, virtual integration may well become a new organizational model for the information age.

  9. Kunstlik viljastamine - kas rahva püsimajäämise võti? / Michael Cook

    Index Scriptorium Estoniae

    Cook, Michael

    2007-01-01

    Kunstlikust viljastamisest pole üksi abi - vaid siis, kui noored mehed ja naised pööravad selja tarbimiskultusele ja individualismile, hakkab sündimus tõusma taastootmisest kõrgemale, kirjutab BioEdge toimetaja Michael Cook

  10. Training and Mastery of Techniques in Wittgenstein's Later Philosophy: A Response to Michael Luntley

    Science.gov (United States)

    Stickney, Jeff

    2008-01-01

    Responding to Michael Luntley's article, "Learning, Empowerment and Judgement," the author shows he cannot successfully make the following three moves: (1) dissolve the analytic distinction between learning by training and learning by reasoning, while advocating the latter; (2) diminish the role of training in Wittgenstein's philosophy, nor…

  11. Vision and Elusiveness in Philosophy of Education: R. S. Peters on the Legacy of Michael Oakeshott

    Science.gov (United States)

    Williams, Kevin

    2009-01-01

    Despite his elusiveness on important issues, there is much in Michael Oakeshott's educational vision that Richard Peters quite rightly wishes to endorse. The main aim of this essay is, however, to consider Peters' justifiable critique of three features of Oakeshott's work. These are (1) the rigidity of his distinction between vocational and…

  12. Hydrogeochemical and stream sediment reconnaissance basic data for St. Michael Quadrangle, Alaska

    International Nuclear Information System (INIS)

    1981-01-01

    Field and laboratory data are presented for 159 water samples from the St. Michael Quadrangle, Alaska. The samples were collected by Los Alamos National Laboratory; laboratory analysis and data reporting were performed by the Uranium Resource Evaluation Project at Oak Ridge, Tennessee

  13. SYNTHESIS OF SOME PROLINE DERIVATIVES BY MEANS OF MICHAEL ADDITIONS OF GLYCINE ESTERS

    NARCIS (Netherlands)

    VANDERWERF, A; KELLOGG, RM

    1991-01-01

    Addition of the Schiff bases derived from reaction of glycine alkyl esters with benzophenoneimine to alpha,beta-unsaturated ketones, followed by hydrogenation of the addition products, leads to 5- or 3,5-substituted prolines. Hydrolysis of the Michael adducts rather than hydrogenation allows

  14. Gulliver's Travels: Michael Moore the Explorer in "Who to Invade Next"

    Science.gov (United States)

    Beck, Bernard

    2016-01-01

    America is identified as a nation of immigrants. These immigrants are thought to be the source of its subcultures. It is also a nation of individual explorers and inventors. Their activities are also a source of diverse subcultures. Many notable movies have made heroes of such innovators in different fields of endeavor. Michael Moore's movie…

  15. A Critical Analysis of Michael Tippett's "A Child of Our Time"

    Science.gov (United States)

    Vallee, Jean-Sebastien

    2009-01-01

    After more than ten years of thoughtful planning, Michael Tippett (1905-1998) summed up his musical, political, spiritual and philosophical beliefs in his first oratorio, "A Child of Our Time" (1941). Representing the emergence of a new level of confidence and musical maturity for Tippett, the oratorio has become the composer's most widely known…

  16. Q & A with Ed Tech Leaders: Interview with Michael W. Allen

    Science.gov (United States)

    Shaughnessy, Michael F.

    2014-01-01

    Michael W. Allen, the Chairman and CEO of Allen Interactions, is an architect of interactive multimedia learning and is recognized for his many insights, inventions, and presentations. With over 50 years of experience in e-learning, both in academic and corporate settings, he is known for his role in creating Authorware and overseeing the work of…

  17. European Management: an emerging competitive advantage of European nations : A reply to Michael Porter

    NARCIS (Netherlands)

    F.A.J. van den Bosch (Frans); A.A. van Prooijen

    1992-01-01

    textabstractThis article extends the debate begun in the June 1992 issue of EMJ when the authors first criticized Michael Porter's explanatory framework in his Competitive Advantage of Nations (1990), over the role of national culture on the competitive advantage of nations. In this paper, Frans van

  18. New Models at Lasell: Q&A with President Michael Alexander

    Science.gov (United States)

    Harney, John O.

    2018-01-01

    The "New England Journal of Higher Education" ("NEJHE") Executive Editor John O. Harney had the chance to catch up with Lasell College President Michael Alexander about the small Newton, Massachusetts, college's plans to challenge the higher education business model. The interview is presented in this article.

  19. Subjectivity and Cultural Adjustment in Mathematics Education: A Response to Wolff-Michael Roth

    Science.gov (United States)

    Brown, Tony

    2012-01-01

    In this volume, Wolff-Michael Roth provides a critical but partial reading of Tony Brown's book "Mathematics Education and Subjectivity". The reading contrasts Brown's approach with Roth's own conception of subjectivity as derived from the work of Vygotsky, in which Roth aims to "reunite" psychology and sociology. Brown's book, however, focuses on…

  20. Little Mosie from the Margaree: A Biography of Moses Michael Coady.

    Science.gov (United States)

    Welton, Michael R.

    This book examines the life of the Reverend Moses Michael Coady (1890-1959), a Roman Catholic priest who led the Antigonish Movement. During the Antigonish Movement, residents of the small maritime town of Antigonish, Nova Scotia, worked to achieve a nonviolent alternative to communism and fascism and to effect the social and economic…

  1. An efficient oxa-Michael addition to diethyl vinylphosphonate under mild reaction conditions

    Czech Academy of Sciences Publication Activity Database

    Baszczyňski, Ondřej; Jansa, Petr; Dračínský, Martin; Kaiser, Martin Maxmilian; Špaček, Petr; Janeba, Zlatko

    2012-01-01

    Roč. 2, č. 4 (2012), s. 1282-1284 ISSN 2046-2069 R&D Projects: GA MV VG20102015046 Institutional research plan: CEZ:AV0Z40550506 Keywords : oxa-Michael addition * secondary alcohols * diethyl vinylphosphonate Subject RIV: CC - Organic Chemistry Impact factor: 2.562, year: 2012

  2. What Work Do the Concepts of "Language" and "Literature" Do for Michael Rosenak?

    Science.gov (United States)

    Levisohn, Jon A.

    2014-01-01

    Michael Rosenak uses the twin metaphors of "language" and "literature," borrowed from Oakeshott and Peters, to argue that the goal of education is initiation into a language. This goal transcends the study of literature in that language. It includes, as well, the development of the capacity both to critique literature and to…

  3. Michael Faraday on the Learning of Science and Attitudes of Mind.

    Science.gov (United States)

    Crawford, Elspeth

    1998-01-01

    Makes use of Michael Faraday's ideas on learning, focusing on his attitudes toward the unknowns of science and the development of an attitude that improves scientific decision making. This approach acknowledges that there is an inner struggle involved in facing unknowns. (DDR)

  4. An Interview with Michael Horn: Blending Education for High-Octane Motivation

    Science.gov (United States)

    Patterson, Gregory A.

    2012-01-01

    Blended learning holds the potential of improving the way we educate students and of making them more motivated. Blended education--the melding of information technology based distance learning with school attendance--is perhaps the best way to educate students for 21st century skills, says Michael Horn in a "Kappan" interview. Horn points out…

  5. DNA-based catalytic enantioselective intermolecular oxa-Michael addition reactions

    NARCIS (Netherlands)

    Megens, Rik P.; Roelfes, Gerard

    2012-01-01

    Using the DNA-based catalysis concept, a novel Cu(II) catalyzed enantioselective oxa-Michael addition of alcohols to enones is reported. Enantioselectivities of up to 86% were obtained. The presence of water is important for the reactivity, possibly by reverting unwanted side reactions such as

  6. C. P. Snow's "The Two Cultures": Michael Polanyi's Response and Context

    Science.gov (United States)

    Jacobs, Struan

    2011-01-01

    C. P. Snow's "The Two Cultures" controversially contrasted science and literature, suggesting that neither scientists nor literary intellectuals have much in common with, and seldom bother speaking to, the other. Responding to Snow, Michael Polanyi argued that specialization has made modern culture, not twofold but manifold. In his major work,…

  7. Noted astrophysicist Michael S. Turner to Head NSF'S mathematical and physical sciences directorate

    CERN Multimedia

    2003-01-01

    "The National Science Foundation has named celebrated astrophysicist Michael S. Turner of the University of Chicago as Assistant Director for Mathematical and Physical Sciences. He will head a $1 billion directorate that supports research in mathematics, physics, chemistry, materials and astronomy, as well as multidisciplinary programs and education" (1/2 page).

  8. 77 FR 69550 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...

    Science.gov (United States)

    2012-11-19

    ... (Patient Satisfaction Survey Michael E. DeBakey Home Care Program) Activity: Comment Request AGENCY.... DeBakey Home Care Program. DATES: Written comments and recommendations on the proposed collection of...: Patient Satisfaction Survey Michael E. DeBakey Home Care Program, VA Form 10-0476. OMB Control Number...

  9. 76 FR 624 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...

    Science.gov (United States)

    2011-01-05

    ... Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program) Activity: Comment Request... satisfaction with the quality of services/care provided by home care program staff. An agency may not conduct... Form 10-0476).'' SUPPLEMENTARY INFORMATION: Title: Patient Satisfaction Survey Michael E. DeBakey Home...

  10. 78 FR 6851 - Proposed Information Collection (Patient Satisfaction Survey Michael E. DeBakey Home Care Program...

    Science.gov (United States)

    2013-01-31

    ... (Patient Satisfaction Survey Michael E. DeBakey Home Care Program) Activity: Comment Request AGENCY... Satisfaction Survey Michael E. DeBakey Home Care Program, VA Form 10-0476. OMB Control Number: 2900-0775. Type... home care program staff. An agency may not conduct or sponsor, and a person is not required to respond...

  11. 77 FR 30047 - Notice of Opportunity for Public Comment on Surplus Property Release at Michael J Smith Field...

    Science.gov (United States)

    2012-05-21

    ... Comment on Surplus Property Release at Michael J Smith Field, Beaufort, NC AGENCY: Federal Aviation... J Smith Field, be used for aeronautical purposes. DATES: Comments must be received on or before June... property at the Michael J Smith Field. The property consists of one parcel located on the north side of...

  12. Analysis of nonlinear optical properties in donor–acceptor materials

    Energy Technology Data Exchange (ETDEWEB)

    Day, Paul N. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); General Dynamics Information Technology, Inc., Dayton, Ohio 45431 (United States); Pachter, Ruth [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Nguyen, Kiet A. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., Dayton, Ohio 45432 (United States)

    2014-05-14

    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{sub 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. Potassium acceptor doping of ZnO crystals

    Directory of Open Access Journals (Sweden)

    Narendra S. Parmar

    2015-05-01

    Full Text Available ZnO bulk single crystals were doped with potassium by diffusion at 950°C. Positron annihilation spectroscopy confirms the filling of zinc vacancies and a different trapping center for positrons. Secondary ion mass spectroscopy measurements show the diffusion of potassium up to 10 μm with concentration ∼1 × 1016 cm−3. IR measurements show a local vibrational mode (LVM at 3226 cm−1, at a temperature of 9 K, in a potassium doped sample that was subsequently hydrogenated. The LVM is attributed to an O–H bond-stretching mode adjacent to a potassium acceptor. When deuterium substitutes for hydrogen, a peak is observed at 2378 cm−1. The O-H peak is much broader than the O-D peak, perhaps due to an unusually low vibrational lifetime. The isotopic frequency ratio is similar to values found in other hydrogen complexes. Potassium doping increases the resistivity up to 3 orders of magnitude at room temperature. The doped sample has a donor level at 0.30 eV.

  14. Potassium acceptor doping of ZnO crystals

    Science.gov (United States)

    Parmar, Narendra S.; Corolewski, Caleb D.; McCluskey, Matthew D.; Lynn, K. G.

    2015-05-01

    ZnO bulk single crystals were doped with potassium by diffusion at 950°C. Positron annihilation spectroscopy confirms the filling of zinc vacancies and a different trapping center for positrons. Secondary ion mass spectroscopy measurements show the diffusion of potassium up to 10 μm with concentration ˜1 × 1016 cm-3. IR measurements show a local vibrational mode (LVM) at 3226 cm-1, at a temperature of 9 K, in a potassium doped sample that was subsequently hydrogenated. The LVM is attributed to an O-H bond-stretching mode adjacent to a potassium acceptor. When deuterium substitutes for hydrogen, a peak is observed at 2378 cm-1. The O-H peak is much broader than the O-D peak, perhaps due to an unusually low vibrational lifetime. The isotopic frequency ratio is similar to values found in other hydrogen complexes. Potassium doping increases the resistivity up to 3 orders of magnitude at room temperature. The doped sample has a donor level at 0.30 eV.

  15. Potassium acceptor doping of ZnO crystals

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, Narendra S., E-mail: nparmar@wsu.edu; Lynn, K. G. [Center for Materials Research, Washington State University, Pullman, Washington 99164-2711 (United States); Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States); Corolewski, Caleb D.; McCluskey, Matthew D. [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States)

    2015-05-15

    ZnO bulk single crystals were doped with potassium by diffusion at 950°C. Positron annihilation spectroscopy confirms the filling of zinc vacancies and a different trapping center for positrons. Secondary ion mass spectroscopy measurements show the diffusion of potassium up to 10 μm with concentration ∼1 × 10{sup 16} cm{sup −3}. IR measurements show a local vibrational mode (LVM) at 3226 cm{sup −1}, at a temperature of 9 K, in a potassium doped sample that was subsequently hydrogenated. The LVM is attributed to an O–H bond-stretching mode adjacent to a potassium acceptor. When deuterium substitutes for hydrogen, a peak is observed at 2378 cm{sup −1}. The O-H peak is much broader than the O-D peak, perhaps due to an unusually low vibrational lifetime. The isotopic frequency ratio is similar to values found in other hydrogen complexes. Potassium doping increases the resistivity up to 3 orders of magnitude at room temperature. The doped sample has a donor level at 0.30 eV.

  16. 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.

  17. Synthesis and optoelectronic characterization of some triphenylamine-based compounds containing strong acceptor substituents

    Energy Technology Data Exchange (ETDEWEB)

    Grigoras, Mircea, E-mail: grim@icmpp.ro; Ivan, Teofilia; Vacareanu, Loredana; Catargiu, Ana Maria; Tigoianu, Radu

    2014-09-15

    Three novel triphenylamine-based compounds containing strong electron acceptor groups have been synthesized and their comparative photophysical properties are presented. These compounds were obtained by a two-step method: (i) triphenylamine compounds with one, two and three phenylacetylene arms were synthesized by Sonogashira reaction between iodine-substituted triphenylamines and phenylacetylene, followed by (ii) post-modification of these electron-rich alkynes by addition of the strong electron acceptor, tetracyanoethylene. Characterization of all oligomers was made by FTIR, {sup 1}H-NMR, UV–vis and fluorescence spectroscopy. A batochromic shifting of the UV and photoluminescence maxima was observed with the increase of the acceptor group number. The electrochemical behavior was studied by cyclic voltammetry. The cyclic voltammograms have evidenced that triphenylamine-phenylacetylene compounds undergo only oxidation processes while compounds modified with tetracyanoethylene show both oxidation and reduction peaks associated with donor and acceptor groups, respectively. The donor–acceptor compounds coordinate metal ions (i.e., Hg{sup 2+} and Sn{sup 2+}) by cyano groups resulting in the decreasing of charge transfer band intensity, and they can be used as chemosensors. - Highlights: • Three triphenylamine-based ethynylene compounds were prepared by Sonogashira reaction. • Post-modification of ethynylene linkages by tetracyanethylene cycloaddition and retroconversion led to donor–acceptor compounds. • Photophysical properties of donor–acceptor oligomers were studied in different solvents.

  18. Impact of Nonfullerene Acceptor Core Structure on the Photophysics and Efficiency of Polymer Solar Cells

    KAUST Repository

    Alamoudi, Maha; Khan, Jafar Iqbal; Firdaus, Yuliar; Wang, Kai; Andrienko, Denis; Beaujuge, Pierre; Laquai, Fré dé ric

    2018-01-01

    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.

  19. Shallow acceptors in strained Ge/Ge1-xSix heterostructures with quantum wells

    International Nuclear Information System (INIS)

    Aleshkin, V.Ya.; Andreev, B.A.; Gavrilenko, V.I.; Erofeeva, I.V.; Kozlov, D.V.; Kuznetsov, O.A.

    2000-01-01

    Dependence of acceptor localized state energies in quantum wells (strained layers of Ge in heterostructures Ge/Ge 1-x Si x ) on the width of quantum well and position in it was studied theoretically. Spectrum of impurity absorption in the far infrared range was calculated. Comparison of the results calculated and observed photoconductivity spectra permits estimating acceptor distribution over quantum well and suggesting conclusion that acceptors can be largely concentrated near heteroboundaries. Absorption spectrum was calculated bearing in mind resonance impurity states, which permits explaining the observed specific features in the photoconductivity spectrum short-wave range by transition to resonance energy levels, bound to upper subzones of dimensional quantization [ru

  20. A Nonfullerene Small Molecule Acceptor with 3D Interlocking Geometry Enabling Efficient Organic Solar Cells.

    Science.gov (United States)

    Lee, Jaewon; Singh, Ranbir; Sin, Dong Hun; Kim, Heung Gyu; Song, Kyu Chan; Cho, Kilwon

    2016-01-06

    A new 3D nonfullerene small-molecule acceptor is reported. The 3D interlocking geometry of the small-molecule acceptor enables uniform molecular conformation and strong intermolecular connectivity, facilitating favorable nanoscale phase separation and electron charge transfer. By employing both a novel polymer donor and a nonfullerene small-molecule acceptor in the solution-processed organic solar cells, a high-power conversion efficiency of close to 6% is demonstrated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Influence of Ubiquitous Electron Acceptors on In Situ Anaerobic Biotransformation of RDX in Groundwater

    National Research Council Canada - National Science Library

    Wani, Altaf

    2003-01-01

    A series of column studies, with aquifer material from the former Nebraska Ordnance Plant, were performed to explore the phenomenon of electron competition from ubiquitous inorganic electron acceptors (nitrate and sulfate...

  2. A survey of acceptor dopants for β-Ga2O3

    Science.gov (United States)

    Lyons, John L.

    2018-05-01

    With a wide band gap, high critical breakdown voltage and commercially available substrates, Ga2O3 is a promising material for next-generation power electronics. Like most wide-band-gap semiconductors, obtaining better control over its electrical conductivity is critically important, but has proven difficult to achieve. Although efficient p-type doping in Ga2O3 is not expected, since theory and experiment indicate the self-trapping of holes, the full development of this material will require a better understanding of acceptor dopants. Here the properties of group 2, group 5 and group 12 acceptor impurities in β-Ga2O3 are explored using hybrid density functional calculations. All impurities are found to exhibit acceptor transition levels above 1.3 eV. After examining formation energies as a function of chemical potential, Mg (followed closely by Be) is determined to be the most stable acceptor species.

  3. Nanographenes as electron-deficient cores of donor-acceptor systems.

    Science.gov (United States)

    Liu, Yu-Min; Hou, Hao; Zhou, Yan-Zhen; Zhao, Xin-Jing; Tang, Chun; Tan, Yuan-Zhi; Müllen, Klaus

    2018-05-15

    Conjugation of nanographenes (NGs) with electro-active molecules can establish donor-acceptor π-systems in which the former generally serve as the electron-donating moieties due to their electronic-rich nature. In contrast, here we report a series of reversed donor-acceptor structures are obtained by C-N coupling of electron-deficient perchlorinated NGs with electron-rich anilines. Selective amination at the vertexes of the NGs is unambiguously shown through X-ray crystallography. By varying the donating ability of the anilino groups, the optical and assembly properties of donor-acceptor NGs can be finely modulated. The electron-deficient concave core of the resulting conjugates can host electron-rich guest molecules by intermolecular donor-acceptor interactions and gives rise to charge-transfer supramolecular architectures.

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

    KAUST Repository

    Nielsen, Christian B.; Holliday, Sarah; Chen, Hung-Yang; Cryer, Samuel J.; McCulloch, Iain

    2015-01-01

    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

  5. On the Molecular Origin of Charge Separation at the Donor-Acceptor Interface

    KAUST Repository

    Sini, Gjergji; Schubert, Marcel; Risko, Chad; Roland, Steffen; Lee, Olivia P.; Chen, Zhihua; Richter, Thomas V.; Dolfen, Daniel; Coropceanu, Veaceslav; Ludwigs, Sabine; Scherf, Ullrich; Facchetti, Antonio; Frechet, Jean; Neher, Dieter

    2018-01-01

    and theoretical approach is used to understand the intimate mechanisms by which molecular structure contributes to exciton dissociation, charge separation, and charge recombination at the donor–acceptor (D–A) interface. Model systems comprised of polythiophene

  6. Brändi näkyy musiikkivideossa : Esimerkkitapaus Michael Jackson

    OpenAIRE

    Kontinen, Noora

    2016-01-01

    Tutkin opinnäytetyössäni brändin ja musiikkivideon suhdetta toisiinsa. Työssä käsitellään lyhyesti myös tähteyttä. Esittelen ensin vähän historiaa ja peruskäsitteitä, minkä jälkeen käytän Michael Jacksonin Billie Jean -musiikkivideota esimerkkinä tutkiessani Michael Jacksonin brändiä. Teoksessa käytetään lähdeaineistoa sekä omaa analyysia. Keskityn tarkastelemaan musiikkivideoita, ja niihin liittyviä sisältöjä yleisesti, ei niinkään teknisesti. Toivon, että työstäni on apua jollekin,...

  7. Interviews with Michael Baxandall, February 3rd and 4th, 1994, Berkeley, CA

    Directory of Open Access Journals (Sweden)

    Allan Langdale

    2009-12-01

    Full Text Available The following interviews with Michael Baxandall were conducted in Berkeley on February 3rd and 4th of 1994. The content of these interviews include general responses about developments in art history in the years between 1960 and 1985, a period of dramatic modifications in the discipline. Among the issues are the rise of the social history of art and the sources from anthropology that informed Baxandall’s concept of the ‘Period Eye’. Baxandall talks about his own work, his personal intellectual history, and the scholars of past and current generations who influenced him. Other topics include Baxandall’s professional trajectory, the Warburg Library, and aspects of cultural history having to do with Renaissance Humanism. These interviews first appeared as an appendix to the PhD dissertation by Allan Langdale, Art History and Intellectual History: Michael Baxandall’s Work between 1963 and 1985, U. C. Santa Barbara, 1995.

  8. [An exceptional human relationship (Michael P. Kierkegaard, Søren Kierkegaard)].

    Science.gov (United States)

    Jacobs, R

    1978-01-01

    There were a father and a son, Michael and Sören Kierkegaard, both highly talented, imaginitive, witty, humorous, especially interested in shrewd dialectrical dialogues respectively debates, both profound melancholy ponderers. But according to very own individuality their congeniality wasn't absolute. The father, being under a questionable rigorous opinion of sin, suffered from undeserved divine grace since early childhood. And Michael Kierkegaard made Sören anxious with the religious experience of original sin. This anxiety moved (touched or affected) the sensitive son mighty. Nevertheless he should not despair hopelessly like his unlucky father. On the contrary: Sørens incomparable melancholy, mental agony and anxiety (fear or anguish) forced the faith, existing independently of them, in a radical refining. That is why Sören Kierkegaard succeeded in sublimation of all psychological and philosophic (al) attitudes (or opinions) in the sphere of religiousness. And the result? A novel philosophy of life: Christian existentialism.

  9. Michael K. Scullin: Psi Chi/APA Edwin B. Newman Graduate Research Award.

    Science.gov (United States)

    2011-11-01

    Presents Michael K. Scullin as the 2011 winner of the American Psychological Association Psi Chi/APA Edwin B. Newman Graduate Research Award. "For an outstanding research paper that examines the relationship between prospective memory in executing a goal and various lapses of time from 20 minutes up to a 12- hour wake delay and a 12-hour sleep delay. The results suggest that consolidation processes active during sleep increase the probability of goal execution. The paper, titled 'Remembering to Execute a Goal: Sleep On It!' was published in Psychological Science in 2010 and was the basis for Michael K. Scullin's selection as the recipient of the 2011 Psi Chi/APA Edwin B. Newman Graduate Research Award. Mark A. McDaniel, PhD, served as faculty research advisor." (PsycINFO Database Record (c) 2011 APA, all rights reserved). 2011 APA, all rights reserved

  10. Navigating Transition: Freedom, Limitation and the Post-colonial Persona in Michael Ondaatje's The Cat's Table

    Directory of Open Access Journals (Sweden)

    Alaa Alghamdi

    2012-11-01

    Full Text Available Michael Ondaatje's 2011 novel The Cat's Table follows a young boy's voyage from Colombo, Sri Lanka to London, England. Through this character and the unique environment of the ship, which forms a compelling sense of transitory place, Ondaatje explores liminality and its relationship with limitations or barriers. The young protagonist, Michael, and his companions enjoy an unusual level of freedom aboard the contained and hierarchically segmented ship. Polarization and transition between Eastern and Western culture is present but pales in importance compared to the validation of the self that is located within and defined by the sense of the in-between, an essential rite of passage undertaken before re-joining society.

  11. Spatial structure of single and interacting Mn acceptors in GaAs

    Science.gov (United States)

    Koenraad, Paul

    2005-03-01

    Ferromagnetic semiconductors such as Ga1-xMnxAs are receiving a lot of attention at the moment because of their application in spintronic devices. However, despite intense study of deep acceptors in III-V semiconductors such as MnGa, little information has been obtained on their electronic properties at the atomic scale. Yet the spatial shape of the Mn acceptor state will influence the hole-mediated Mn-Mn coupling and thus all of the magnetic properties of ferromagnetic semiconductors such as Ga1-xMnxAs. This study presents an experimental and theoretical description of the spatial symmetry of the Mn acceptor wave-function in GaAs. We present measurements of the spatial mapping of the anisotropic wavefunction of a hole localized at a Mn acceptor. To achieve this, we have used the STM tip not only to image the Mn acceptor but also to manipulate its charge state A^0/A^- at room temperature. Within an envelope function effective mass model (EFM) the anisotropy in the acceptor wave-function can be traced to the influence of the cubic symmetry of the GaAs crystal which selects specific d-states that mix into the ground state due to the spin-orbit interaction in the valence band. Comparison with calculations based on a tight-binding model (TBM) for the Mn acceptor structure supports this conclusion. Using the same experimental and theoretical approach we furthermore explored the interaction between Mn acceptors directly by analyzing close Mn-Mn pairs, which were separated by less than 2 nm. We will discuss some implications of these results for Mn delta-doped layers grown on differently oriented growth surfaces.

  12. Learned Helplessness Encountered by Michael Oher in the Blind Side Movie

    OpenAIRE

    PAMUNGKAS, DIMAS PROBO

    2014-01-01

    Pamungkas, Dimas Probo. 2014. Learned Helplessness Encountered by Michael Oher in The Blind Side Movie. Study Program of English, Department of Languages and Literature, Faculty of Culture Studies, Universitas Brawijaya. Supervisor: Dyah Eko Hapsari;Co-supervisor: Sarlettina Vidyayani EkaKeywords: Learned Helplessness, African-American, Psychological, Social Behavior, Depression, The Blind Side.Social behavior shows several interactions between person and social situations, which stress...

  13. Dropping The Bomb? On Critical and Cinematic Reactions to Michael Ondaatje's The English Patient

    OpenAIRE

    Pesch, Josef

    2018-01-01

    This paper analyses Anthony Minghella's film adaptation of Michael Ondaatje’s The English Patient. It aims at establishing patterns of transformation and strategies of adaptation. Not only the nostalgie romanticisation, but also the de-politicisation of the novel is critically scrutinized. As dropping all reference to the atomic bomb from the film is the most blatant example of deviation from the novel, critical and political background is provided which may explain this act of self-censorshi...

  14. Organocatalytic asymmetric michael addition of aldehydes to beta-nitroacroleine dimethyl acetal.

    Science.gov (United States)

    Reyes, Efraim; Vicario, Jose L; Badía, Dolores; Carrillo, Luisa

    2006-12-21

    [Structure: see text] The organocatalytic asymmetric Michael addition of aldehydes to beta-nitroacroleine dimethyl acetal has been studied in detail. The reaction took place with excellent yields and high stereoselectivities when a chiral beta-amino alcohol such as L-prolinol was employed as the catalyst, leaving a formation of highly functionalized enantioenriched compounds containing two differentiated formyl groups together with a nitro moiety.

  15. Horror movie aspects and experimentation in Michael Jackson’s Thriller music video

    OpenAIRE

    Vargas, Herom; Universidade Municipal de São Caetano do Sul - USCS; Gonçalves, Rafael; Universidade Municipal de São Caetano do Sul - USCS

    2016-01-01

    This article analyzes the use of elements from the horror fi lm genre in the music video Thriller (1982), by Michael Jackson, as experimentation within the field of pop music. Based on the semiotics of culture, grounded on the concepts of cultural text, semiosphere, border and modeling, developed by Iuri Lotman, the analysis identified innovations in the use of horror as humor and, in the music, modeling of creatures, moving among horror, the fantastic and the reality.Keywords: horror, music ...

  16. Review: Cornelia Behnke & Michael Meuser (1999). Geschlechterforschung und qualitative Methoden [Gender Research and Qualitative Methods

    OpenAIRE

    Nicola Döring

    2001-01-01

    In less than 100 pages Cornelia BEHNKE and Michael MEUSER explain how gender studies evolved from women's studies and what feminist methodology is all about. They also discuss the interrelation of qualitative research and gender studies. The great potential of qualitative research based on a constructivist gender concept is demonstrated with a group discussion study involving different men only groups. Finally the authors deal with the question of how the researcher's gender affects both data...

  17. Feeding Health: Michael Pollan on Improving Public Health through the Food Systems

    Centers for Disease Control (CDC) Podcasts

    2009-08-19

    In this podcast, author Michael Pollan discusses his March 2009 visit to CDC and offers his thoughts on the intersection between the government, the food systems, and public health.  Created: 8/19/2009 by National Center for Environmental Health (NCEH), National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP), Office of Sustainability.   Date Released: 4/15/2010.

  18. Spectroscopic studies of charge transfer complexes of some amino aromatic donors with some acceptors

    International Nuclear Information System (INIS)

    Al-Ani, S.S.

    1989-01-01

    Charge transfer (C.T.) complexes are the products of the weak reversible interactions between electron donors and electron acceptors. Sixteen novel C.T. complexes were studied and discussed. These complexes were formed from aromatic electron donors with various electron acceptors in absolute ethyl alcohol at 20 0 C. Electronic absorption spectra of these complexes and their donors and acceptors were taken. New charge transfer absorption bands appeared for these complexes in the UV-VIS region. The donors used are tetramethyl diamino benzophenone, P-amino-N:N-dimethyl aniline, tetramethyl-diamino-diphenylmethane, P-amino-azobenzene and benzidine, while the acceptors are iodine, bromine, picric acid, 2,4-dinitrophenol, trifluoroacetic acid and trichloroacetic acid. The results showed a disappearance of some donors and acceptors absorption bands. The energy of C.T. bands were calculated from which the ionization potentials of donors were obtained. The results showed that energies of C.T. Bands for complexes of a given donor with a series of acceptors are very similar. Some C.T. complexes showed low value of energy and high values of electrical conductivity. These are ionic complexes rather than molecular ones. 4 tabs.; 2 figs.; 99 refs

  19. 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.

  20. The Effect of Acceptor and Donor Doping on Oxygen Vacancy Concentrations in Lead Zirconate Titanate (PZT).

    Science.gov (United States)

    Slouka, Christoph; Kainz, Theresa; Navickas, Edvinas; Walch, Gregor; Hutter, Herbert; Reichmann, Klaus; Fleig, Jürgen

    2016-11-22

    The different properties of acceptor-doped (hard) and donor-doped (soft) lead zirconate titanate (PZT) ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly suppress their amount. In this study, La 3+ donor-doped, Fe 3+ acceptor-doped and La 3+ /Fe 3+ -co-doped PZT samples were investigated by oxygen tracer exchange and electrochemical impedance spectroscopy in order to analyse the effect of doping on oxygen vacancy concentrations. Relative changes in the tracer diffusion coefficients for different doping and quantitative relations between defect concentrations allowed estimates of oxygen vacancy concentrations. Donor doping does not completely suppress the formation of oxygen vacancies; rather, it concentrates them in the grain boundary region. Acceptor doping enhances the amount of oxygen vacancies but estimates suggest that bulk concentrations are still in the ppm range, even for 1% acceptor doping. Trapped holes might thus considerably contribute to the charge balancing of the acceptor dopants. This could also be of relevance in understanding the properties of hard and soft PZT.

  1. The Effect of Acceptor and Donor Doping on Oxygen Vacancy Concentrations in Lead Zirconate Titanate (PZT

    Directory of Open Access Journals (Sweden)

    Christoph Slouka

    2016-11-01

    Full Text Available The different properties of acceptor-doped (hard and donor-doped (soft lead zirconate titanate (PZT ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly suppress their amount. In this study, La3+ donor-doped, Fe3+ acceptor-doped and La3+/Fe3+-co-doped PZT samples were investigated by oxygen tracer exchange and electrochemical impedance spectroscopy in order to analyse the effect of doping on oxygen vacancy concentrations. Relative changes in the tracer diffusion coefficients for different doping and quantitative relations between defect concentrations allowed estimates of oxygen vacancy concentrations. Donor doping does not completely suppress the formation of oxygen vacancies; rather, it concentrates them in the grain boundary region. Acceptor doping enhances the amount of oxygen vacancies but estimates suggest that bulk concentrations are still in the ppm range, even for 1% acceptor doping. Trapped holes might thus considerably contribute to the charge balancing of the acceptor dopants. This could also be of relevance in understanding the properties of hard and soft PZT.

  2. Electron paramagnetic resonance study of neutral Mg acceptors in β-Ga2O3 crystals

    Science.gov (United States)

    Kananen, B. E.; Halliburton, L. E.; Scherrer, E. M.; Stevens, K. T.; Foundos, G. K.; Chang, K. B.; Giles, N. C.

    2017-08-01

    Electron paramagnetic resonance (EPR) is used to directly observe and characterize neutral Mg acceptors ( M gGa0 ) in a β-Ga2O3 crystal. These acceptors, best considered as small polarons, are produced when the Mg-doped crystal is irradiated at or near 77 K with x rays. During the irradiation, neutral acceptors are formed when holes are trapped at singly ionized Mg acceptors ( M gGa- ). Unintentionally present Fe3+ (3d5) and Cr3+ (3d3) transition-metal ions serve as the corresponding electron traps. The hole is localized in a nonbonding p orbital on a threefold-coordinated oxygen ion adjacent to an Mg ion at a sixfold-coordinated Ga site. These M gGa0 acceptors (S = 1/2) have a slightly anisotropic g matrix (principal values are 2.0038, 2.0153, and 2.0371). There is also partially resolved 69Ga and 71Ga hyperfine structure resulting from unequal interactions with the two Ga ions adjacent to the hole. With the magnetic field along the a direction, hyperfine parameters are 2.61 and 1.18 mT for the 69Ga nuclei at the two inequivalent neighboring Ga sites. The M gGa0 acceptors thermally convert back to their nonparamagnetic M gGa- charge state when the temperature of the crystal is raised above approximately 250 K.

  3. En memoria de Michael Jiménez (1948-2001

    Directory of Open Access Journals (Sweden)

    Mauricio Archila Neira

    2001-01-01

    Full Text Available El 1 de septiembre de 2001 murió el historiador Michael Jiménez. Su apellido provenía de España de donde emigró su abuelo en busca de mejor suerte al otro lado del Atlántico. Nacido en el pequeño pueblo de Merced, California (Estados Unidos en agosto de 1948 en el seno de una familia obrera, Michael vivió su infancia en Colombia. A fines de ese año, su padre se desplazó a estas tierras para ser funcionario de la Texas, una multinacional petrolera que tenía sus reales en Puerto Boyacá. Michael estudió en el colegio Nueva Granada -becado por la Texas- hasta los catorce años. En dicho colegio fue compañero de pupitre de Herbert Braun, descendiente a su vez de una familia de emigrantes a Colombia, y con quien la vida lo juntaría de nuevo en las tierras del norte y en oficios similares.

  4. Between Irish National Cinema and Hollywood: Neil Jordan’s Michael Collins

    Directory of Open Access Journals (Sweden)

    Raita Merivirta-Chakrabarti

    2007-03-01

    Full Text Available When Neil Jordan’s film Michael Collins was released in 1996, it was seen by some as a Hollywood epic, by others as a great national film. I would argue that Michael Collins combines these two traditions and occupies a space between Irish national cinema and Hollywood. The subject matter, the creative talent and the locations were Irish and the film was produced by using the Irish filmmaking infrastructure and the Irish government’s support mechanisms, but it was largely financed and distributed by a Hollywood studio. Also, to make it more appealing especially globally, but probably also locally (since Hollywood is now the international standard, it makes use of Hollywood conventions, making it accessible to international audiences as well. Despite the Hollywood mode, the fact remains that Michael Collins is a national film text, and Jordan does not make too many concessions to the non-Irish audiences.

  5. A celebration of mechanics: from nano to macro. The J. Michael T. Thompson Festschrift issue.

    Science.gov (United States)

    Elishakoff, Isaac

    2013-06-28

    This Theme Issue is dedicated to the topic 'Mechanics: from nano to macro' and marks the 75th birthday of Dr J. Michael T. Thompson, Fellow of the Royal Society, whose current affiliations are as follows: (i) Honorary Fellow, Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge; (ii) Emeritus Professor of Nonlinear Dynamics, Department of Civil, Environmental and Geomatic Engineering, University College London; and (iii) Professor of Theoretical and Applied Dynamics (Distinguished Sixth Century Chair, part-time), University of Aberdeen. He also serves as Chairman of the Board of Directors at ES-Consult (consulting engineers) in Copenhagen, Denmark. The pertinent question that arises from the very start is: should we first salute Michael and then describe the Theme Issue, or vice versa? Indeed, according to Blaise Pascal (1623-1662), the last thing one discovers in composing a work is what to put first. I would like to take the liberty of deviating from the tradition of the Philosophical Transactions and start with the tribute to Michael; after all he is the prime cause of this Theme Issue.

  6. The conceptualization of love in religious thought of George Florovsky and Michael Pomazansky

    Directory of Open Access Journals (Sweden)

    Pavenkov Oleg Vladimirovich

    2015-04-01

    Full Text Available The present article is concerned with the question of conceptualization of love in works of Fr. George Florovsky and Fr. Michael Pomazansky, Russian religious thinkers and theologists. We are studying the meaning and appropriacy of two words, ‘love’ (English and ‘любовь’ (Russian, that are the best to represent the agapelogical positive evaluation in Russian religious thought. Data for study was taken from ten different articles and extracts from books written by Fr. George Florovsky and Fr. Michael Pomazansky. On the basis of this analysis we develop semantic explications of words ‘love’ and ‘любовь’ as Christian spiritual concepts within the framework of theoretical approach of Natural Semantic Metalanguage (NSM. In summary we state that this article discusses, describes and determines some similarities and differences in understanding of concept ‘love’ in the affore-referenced works by Fr. George Florovsky and Fr. Michael Pomazansky.

  7. A perspectiva de Michael Apple para os estudos das políticas educacionais

    Directory of Open Access Journals (Sweden)

    Luís Armando Gandin

    Full Text Available Resumo Este artigo tem como objetivo analisar as contribuições de Michael Apple para o campo da pesquisa em políticas educacionais. Na extensa obra de Michael Apple, destacamos seis elementos que podem auxiliar aqueles que estão interessados na área de políticas em educação: o princípio epistemológico da análise relacional; o exame do Estado como relação; a herança de Antonio Gramsci e de Raymond Williams que Michael Apple incorpora no uso de conceitos como hegemonia e senso comum; a análise que Michael Apple faz das políticas educacionais como políticas culturais, como disputas por visão de mundo, como luta por consolidação de uma hegemonia que vai além do econômico; a sua postura de pesquisador; e a capacidade que Michael Apple tem de ir além da lógica da reprodução e determinação para enfatizar o papel da agência e da contra-hegemonia. Através de exemplos práticos da própria obra de Apple e de outras pesquisas empíricas, apresentam-se as implicações de cada um dos seis pontos acima citados para os pesquisadores interessados na área de políticas educacionais. Conclui-se que muitas das contribuições de Apple podem auxiliar em pesquisas nessa área, tendo em vista a discussão que o autor realiza em sua obra e sua crítica ao determinismo econômico nas análises do campo educacional, salientando a importância, assim, de aspectos que estão relacionados à esfera da cultura.

  8. 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

  9. Tagasipöördumine esteetika juurde = Return to aesthetics / Keith Moxey, Michael Ann Holly ; interv. Anu Allas

    Index Scriptorium Estoniae

    Moxey, Keith

    2007-01-01

    Ameerika kunstiajaloolased Keith Moxey ning Michael Ann Holly tutvustavad uut lähenemist kunstiajaloole (new art history). Nn. naasmine esteetika juurde tähendab püüet integreerida kunstiajalukku ja -teooriasse uuesti ja tugevamalt kunstiteos

  10. Review: Barr, Michael and Zlatko Skrbiš (2008, Constructing Singapore. Elitism, Ethnicity and the Nation-Building Project

    Directory of Open Access Journals (Sweden)

    Boris Michel

    2009-01-01

    Full Text Available Review of the monograph: Barr, Michael and Zlatko Skrbiš, Constructing Singapore. Elitism, Ethnicity and the Nation-Building Project, Copenhagen: NIAS Press, 2008, ISBN 978-87-7694-029-4, 304 pages

  11. Correction: Synthesis of pyrrolidine-3-carboxylic acid derivatives via asymmetric Michael addition reactions of carboxylate-substituted enones.

    Science.gov (United States)

    Yin, Feng; Garifullina, Ainash; Tanaka, Fujie

    2018-04-25

    Correction for 'Synthesis of pyrrolidine-3-carboxylic acid derivatives via asymmetric Michael addition reactions of carboxylate-substituted enones' by Feng Yin et al., Org. Biomol. Chem., 2017, 15, 6089-6092.

  12. Tandem Knoevenagel–Michael reactions in aqueous diethylamine medium: A greener and efficient approach toward bis-dimedone derivatives

    Directory of Open Access Journals (Sweden)

    Abdullah Mohammed Al-Majid

    2017-02-01

    The use of inexpensive, eco-friendly and readily available reagents, easy work-up, and high purity products makes the procedure a convenient and robust method for the synthesis of tandem Knoevenagel–Michael adducts.

  13. Michael T. Westrate. Living Soviet in Ukraine from Stalin to Maidan: Under the Falling Red Star in Kharkiv.

    Directory of Open Access Journals (Sweden)

    Charitie V. Hyman

    2017-09-01

    Full Text Available Book review of Michael T. Westrate. Living Soviet in Ukraine from Stalin to Maidan: Under the Falling Red Star in Kharkiv. Rowman & Littlefield, 2016. xx, 232 pp. Illustrations. Appendices. Bibliography. Index. $85.00, cloth.

  14. The big picture : What the Baltics may learn from Ireland's success story / Michael Bourke ; interv. Maris Biezaitis

    Index Scriptorium Estoniae

    Bourke, Michael

    2002-01-01

    Ilmunud ka: Baltiiskii kurss 2002/Zima/Vesna nr. 20 lk. 14-17. Iirimaa aukonsul Lätis, Michael Joseph Bourke arutleb Iirimaa majandusedu teemal ning pakub välja, mida Baltimaad saaksid sellest õppida. Tabel, diagramm. Lisa

  15. Review: Michael Crandall & Karen E. Fisher (Eds) Digital Inclusion: Measuring the Impact of Information and Community Technology

    DEFF Research Database (Denmark)

    Pors, Niels Ole

    2010-01-01

    Review: Michael Crandall & Karen E. Fisher (Eds) Digital Inclusion: Measuring the Impact of Information and Community Technology. Medford. Information Today. ASIS&T Monographs, 2009. 185 pages. $ 59.50. ISBN 978-1-57387-373-4......Review: Michael Crandall & Karen E. Fisher (Eds) Digital Inclusion: Measuring the Impact of Information and Community Technology. Medford. Information Today. ASIS&T Monographs, 2009. 185 pages. $ 59.50. ISBN 978-1-57387-373-4...

  16. Donor assists acceptor binding and catalysis of human α1,6-fucosyltransferase.

    Science.gov (United States)

    Kötzler, Miriam P; Blank, Simon; Bantleon, Frank I; Wienke, Martin; Spillner, Edzard; Meyer, Bernd

    2013-08-16

    α1,6-Core-fucosyltransferase (FUT8) is a vital enzyme in mammalian physiological and pathophysiological processes such as tumorigenesis and progress of, among others, non-small cell lung cancer and colon carcinoma. It was also shown that therapeutic antibodies have a dramatically higher efficacy if the α1,6-fucosyl residue is absent. However, specific and potent inhibitors for FUT8 and related enzymes are lacking. Hence, it is crucial to elucidate the structural basis of acceptor binding and the catalytic mechanism. We present here the first structural model of FUT8 in complex with its acceptor and donor molecules. An unusually large acceptor, i.e., a hexasaccharide from the core of N-glycans, is required as minimal structure. Acceptor substrate binding of FUT8 is being dissected experimentally by STD NMR and SPR and theoretically by molecular dynamics simulations. The acceptor binding site forms an unusually large and shallow binding site. Binding of the acceptor to the enzyme is much faster and stronger if the donor is present. This is due to strong hydrogen bonding between O6 of the proximal N-acetylglucosamine and an oxygen atom of the β-phosphate of GDP-fucose. Therefore, we propose an ordered Bi Bi mechanism for FUT8 where the donor molecule binds first. No specific amino acid is present that could act as base during catalysis. Our results indicate a donor-assisted mechanism, where an oxygen of the β-phosphate deprotonates the acceptor. Knowledge of the mechanism of FUT8 is now being used for rational design of targeted inhibitors to address metastasis and prognosis of carcinomas.

  17. Metabolic response of Geobacter sulfurreducens towards electron donor/acceptor variation

    Directory of Open Access Journals (Sweden)

    Lovley Derek R

    2010-11-01

    Full Text Available Abstract Background Geobacter sulfurreducens is capable of coupling the complete oxidation of organic compounds to iron reduction. The metabolic response of G. sulfurreducens towards variations in electron donors (acetate, hydrogen and acceptors (Fe(III, fumarate was investigated via 13C-based metabolic flux analysis. We examined the 13C-labeling patterns of proteinogenic amino acids obtained from G. sulfurreducens cultured with 13C-acetate. Results Using 13C-based metabolic flux analysis, we observed that donor and acceptor variations gave rise to differences in gluconeogenetic initiation, tricarboxylic acid cycle activity, and amino acid biosynthesis pathways. Culturing G. sulfurreducens cells with Fe(III as the electron acceptor and acetate as the electron donor resulted in pyruvate as the primary carbon source for gluconeogenesis. When fumarate was provided as the electron acceptor and acetate as the electron donor, the flux analysis suggested that fumarate served as both an electron acceptor and, in conjunction with acetate, a carbon source. Growth on fumarate and acetate resulted in the initiation of gluconeogenesis by phosphoenolpyruvate carboxykinase and a slightly elevated flux through the oxidative tricarboxylic acid cycle as compared to growth with Fe(III as the electron acceptor. In addition, the direction of net flux between acetyl-CoA and pyruvate was reversed during growth on fumarate relative to Fe(III, while growth in the presence of Fe(III and acetate which provided hydrogen as an electron donor, resulted in decreased flux through the tricarboxylic acid cycle. Conclusions We gained detailed insight into the metabolism of G. sulfurreducens cells under various electron donor/acceptor conditions using 13C-based metabolic flux analysis. Our results can be used for the development of G. sulfurreducens as a chassis for a variety of applications including bioremediation and renewable biofuel production.

  18. 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

  19. 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.

  20. Acceptors related to group I elements in ZnO ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kushnirenko, V.I. [V. Lashkarev Institute of Semiconductor Physics, NAS of Ukraine, Pr. Nauky 45, Kiev 03028 (Ukraine); Markevich, I.V., E-mail: ivmarkevich@ukr.net [V. Lashkarev Institute of Semiconductor Physics, NAS of Ukraine, Pr. Nauky 45, Kiev 03028 (Ukraine); Zashivailo, T.V. [National Technical University of Ukraine ' KPI' , Pr. Pobedy 37, Kiev 03056 (Ukraine)

    2012-08-15

    ZnO ceramics doped with Li, Na or K were sintered in air for 4 h at 1000 Degree-Sign C. Electrical conductivity as well as photoluminescence (PL), PL excitation and photoconductivity spectra were measured and compared with those in undoped samples. The influence of both fast and slow cooling of the samples from 1000 Degree-Sign C on measured characteristics was investigated. The yellow-orange PL bands associated with the deep acceptors Li{sub Zn}, Na{sub Zn} and K{sub Zn} were observed and the corresponding PL excitation spectra were determined. These acceptors were found to form some complexes with other lattice defects. - Highlights: Black-Right-Pointing-Pointer Centers related to Li, Na and K impurities in zinc oxide were investigated. Black-Right-Pointing-Pointer It was shown that Li{sub Zn}, Na{sub Zn} and K{sub Zn} centers were deep acceptors responsible for yellow-orange PL bands. Black-Right-Pointing-Pointer These acceptors were found to form some complexes with other lattice defects. Black-Right-Pointing-Pointer The formation of shallow acceptors due to doping ZnO ceramics with Li, Na and K was not found.

  1. Compassionate leadership? Some reflections on the work and life of Michael Lapsley

    Directory of Open Access Journals (Sweden)

    Ian A. Nell

    2016-03-01

    Full Text Available In June 2007, I had the privilege of attending a Healing of Memories workshop lead by Father Michael Lapsley, one of the founder members of the Institute for Healing of Memories. The purpose of the workshop was to help the predominantly white members of a middle class Dutch Reformed congregation in the Northern Suburbs of Cape Town and the predominantly coloured members of a congregation of the Evangelical Lutheran Church in Elsies River on the Cape Flats, to share their stories of the past with regard to apartheid with each other. Apart from the stories that were told and the sharing of experiences about the apartheid history that took place, I was struck by the way in which Father Lapsley conducted the workshop. There was a deep compassion for all the participants as was embodied through the way in which he treated each of us with respect. But apart from his cordiality in leading the workshop, one could sense a deeper source of compassion, a source revealing a compassionate understanding of God�s presence amidst the violence and turmoil in our broken world. The aim of this article is to reflect on whether one could speak of something like �compassionate leadership�, and to take a closer look at the relationship between compassion and God images in the life and work of Michael Lapsley. Special attention will be given to the way in which he exercises leadership through his many involvements related to his own personal story of trauma.Intradisciplinary and/or interdisciplinary implications: This article presents literary research on the notion of compassionate leadership as a specific kind of leadership. The results indicate that the leadership of Father Michael Lapsley does indeed portray features of this kind of leadership. The research can become the source for finding new strategies for religious leadership.

  2. An Interview with Michael Betancourt, author of Agnotology & Crisis in Digital Capitalism

    OpenAIRE

    Sean Scanlan; Michael Betancourt

    2015-01-01

    Sean Scanlan, NANO's editor, interviews artist, curator, art historian and critical theorist Michael Betancourt to discuss the nature of agnotology, a term that means the “creation of uncertainty and ambivalent ‘fact’; it is a competitive tool incompatible with the idealized ‘free market’ of capitalism.” Betancourt is skeptical of Big Data and the ways that the consumers who unknowingly “produce” data for business interpretation are increasingly becoming transformed into a “token of exchange ...

  3. Athlete endorsement as a marketing strategy: a case study of Nike and Michael Jordan

    OpenAIRE

    Masár Vieites, Laura Virginia

    2014-01-01

    Les empreses intenten obrir mercats nous constantment, aconseguint atraure nous clients objectiu i augmentar el reconeixement de la marca. Aquest treball investiga el cóm i per què el patrocini d'atletes, per a que aquests representin els productes d'una empresa, ja que és una eina cada vegada més àmplia i popular en el màrqueting mix de les empreses. Michael Jordan, un estel retirada de bàsquet, ha rebut molta atenció dels mitjans publicitaris i ha representat sota patrocini a diversos produ...

  4. [The problem of evil in families--the filmmaker Michael Haneke].

    Science.gov (United States)

    Skårderud, Finn

    2010-09-23

    With the beautiful and dark film "The white ribbon", from 2009, the Austrian film director Michael Haneke consolidated his status as an international success. A central theme in his films is evilness and its roots. But just as important is his ambition to develop films where evil is not only portrayed, but where spectators are challenged to relate to their own ethical standards and their role as spectators. Haneke is a highly original filmmaker with his consistent search for a film aesthetic that stimulates ethical self-reflection and mentalizing. He partly succeeds in this quest.

  5. Organocatalytic Michael and Friedel–Crafts reactions in enantioselective synthesis of biologically active compounds

    International Nuclear Information System (INIS)

    Maltsev, O V; Beletskaya, Irina P; Zlotin, Sergei G

    2011-01-01

    Recent applications of organocatalytic Michael and Friedel–Crafts reactions in enantioselective synthesis of biologically active compounds: natural products, pharmaceutical agents and plant protection agents are reviewed. The key mechanisms of stereoinduction, types of organocatalysts and reagents used in these reactions are considered. The material is classified according to the type of newly formed bonds incorporating the asymmetric carbon atom, and the information for the most numerous C–C coupling reactions is systematized according to the natures of the electrophile and the nucleophile. The bibliography includes 433 references.

  6. The Great War and All That in A Hundred Doors by Michael Longley

    Directory of Open Access Journals (Sweden)

    Elisabeth Delattre

    2015-03-01

    Full Text Available The Great War has featured regularly in Michael Longley’s poetry, for personal, family, aesthetic and political reasons. His collection published in 2011 under the title A Hundred Doors contains a number of poems relating to his father and the so-called War Poets, in connection with others in which love and nature, life and death are also dominant themes. This article will show how, as elsewhere in his poetry, everything is interrelated, “the nature poetry”, in Longley’s words, “fertilizing the war poetry”.

  7. European Management: an emerging competitive advantage of European nations: A reply to Michael Porter

    OpenAIRE

    Bosch, Frans; Prooijen, A.A.

    1992-01-01

    textabstractThis article extends the debate begun in the June 1992 issue of EMJ when the authors first criticized Michael Porter's explanatory framework in his Competitive Advantage of Nations (1990), over the role of national culture on the competitive advantage of nations. In this paper, Frans van den Bosch and Arno van Prooijen stress that Europe is a locus of competitive advantage if one is prepared to pay attention to the possibility of ‘European Management’ as a potential asset of Europ...

  8. POLYETHYLENEIMINE (PEI ON SILICA AS CATALYST IN KNOEVENAGEL AND MICHAEL REACTIONS

    Directory of Open Access Journals (Sweden)

    FATIHA ZAOUI

    2017-03-01

    Full Text Available After the synthesis of polyethylenimine supported on silica, it has been used as a new and efficient catalyst in Knoevenagel and Michael condensations. The presence of the polyethylenimine in the catalytic system together with silica displays an acido-basic character allows a better catalytic activity in the condensations. Carried out under microwave irradiation, without organic solvent and during short time, the syntheses are respectful towards green chemistry. The solid catalyst can be easily reused. This catalyst has the acido-basic character at the same time.

  9. Electroluminescence from charge transfer states in Donor/Acceptor solar cells

    DEFF Research Database (Denmark)

    Sherafatipour, Golenaz; Madsen, Morten

    Charge photocurrent generation is a key process in solar energy conversion systems. Effective dissociation of the photo-generated electron-hole pairs (excitons) has a strong influence on the efficiency of the organic solar cells. Charge dissociation takes place at the donor/acceptor interface via...... which the maximum open-circuit voltage can be estimated, and further can be used in the modeling and optimization of the OPV devices. [1] C. Deibe, T. Strobe, and V. Dyakonov, “Role of the charge transfer state in organic donor-acceptor solar cells,” Adv. Mater., vol. 22, pp. 4097–4111, 2010. [2] K...... charge transfer (CT) excitons, which is Coulombically bound interfacial electron- hole pairs residing at the donor/acceptor heterojunctions. The CT state represents an intermediate state between the exciton dissociation and recombination back to the ground state. Since the recombination of photo...

  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. The Physics of Small Molecule Acceptors for Efficient and Stable Bulk Heterojunction Solar Cells

    KAUST Repository

    Gasparini, Nicola; Wadsworth, Andrew; Moser, Maximilian; Baran, Derya; McCulloch, Iain; Brabec, Christoph J.

    2018-01-01

    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.

  12. 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.

  13. 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

  14. Shallow acceptors in Ge/GeSi heterostructures with quantum wells in magnetic field

    International Nuclear Information System (INIS)

    Aleshkin, V.Ya.; Antonov, A.V.; Veksler, D.B.; Gavrilenko, V.I.; Erofeeva, I.V.; Ikonnikov, A.V.; Kozlov, D.V.; Spirin, K.E.; Kuznetsov, O.A.

    2005-01-01

    One investigated both theoretically and experimentally into shallow acceptors in Ge/GeSi heterostructures with quantum wells (QW) in a magnetic field. It is shown that alongside with lines of cyclotron resonance in magnetoabsorption spectra one observes transitions from the ground state of acceptor to the excited ones associated with the Landau levels from the first and the second subbands of dimensional quantization, and resonance caused by ionization of A + -centres. To describe impurity transitions in Ge/GeSi heterostructures with QW in a magnetic field and to interpret the experiment results in detail one uses numerical method of calculation based on expansion of wave function of acceptor in terms of basis of wave functions of holes in QW in the absence of magnetic field [ru

  15. 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.

  16. 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......) while compared to Ph(DPP)2. Therefore, the resulting P3HT:PhDMe(DPP)2 based OSCs shows a better power conversion efficiency (PCE) of 0.65%, higher than that from P3HT:Ph(DPP)2 based OSCs (0.48%), which can be ascribed to more efficient exciton dissociation and electron transportation in the active layer...

  17. 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

  18. Magnetic field effect on the Coulomb interaction of acceptors in semimagnetic quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Kalpana, P.; Merwyn, A.; Nithiananthi, P.; Jayakumar, K., E-mail: kjkumar-gri@rediffmail.com [Nanostructure Lab, Department of Physics, Gandhigram Rural University, Gandhigram-624302 (India); Reuben, Jasper D. [Department of Physics, School of Engineering, Saveetha University, Thandalam, Chennai- 600104 (India)

    2015-06-24

    The Coulomb interaction of holes in a Semimagnetic Cd{sub 1-x}Mn{sub x}Te / CdTe Spherical and Cubical Quantum Dot (SMQD) in a magnetic field is studied using variational approach in the effective mass approximation. Since these holes in QD show a pronounced collective behavior, while distinct single particle phenomena is suppressed, their interaction in confined potential becomes very significant. It has been observed that acceptor-acceptor interaction is more in cubical QD than in spherical QD which can be controlled by the magnetic field. The results are presented and discussed.

  19. Magnetic field effect on the Coulomb interaction of acceptors in semimagnetic quantum dot

    Science.gov (United States)

    Kalpana, P.; Merwyn, A.; Reuben, Jasper D.; Nithiananthi, P.; Jayakumar, K.

    2015-06-01

    The Coulomb interaction of holes in a Semimagnetic Cd1-xMnxTe / CdTe Spherical and Cubical Quantum Dot (SMQD) in a magnetic field is studied using variational approach in the effective mass approximation. Since these holes in QD show a pronounced collective behavior, while distinct single particle phenomena is suppressed, their interaction in confined potential becomes very significant. It has been observed that acceptor-acceptor interaction is more in cubical QD than in spherical QD which can be controlled by the magnetic field. The results are presented and discussed.

  20. Interaction of point intrinsic defects in n-type indium phosphide with acceptor clusters

    International Nuclear Information System (INIS)

    Vitovskij, N.A.; Lagunova, T.S.; Rakhimov, O.

    1984-01-01

    The rates of implanting defects of donor- and acceptor type stable at room temperature in n-InP during gamma irradiation are found to vary versus the compensating impurity type. Zinc atoms interact with defects most actively. Irradiation also brings about the growth of acceptor clusters, this growth being most markedly expressed in InP . The presence of an additional mechanism of charge-carriers scattering associated with the existence of clusters of compensating centres is verified, the temperature dependence of the effectiveness of this mechanism μ approximately Tsup(-1.2) is found

  1. Design, synthesis and photovoltaic properties of a series of new acceptor-pended conjugated polymers

    Institute of Scientific and Technical Information of China (English)

    Zhihong; Wu; Yongxiang; Zhu; Wei; Li; Yunping; Huang; Junwu; Chen; Chunhui; Duan; Fei; Huang; Yong; Cao

    2016-01-01

    A series of novel acceptor-pended conjugated polymers featuring a newly developed carbazole-derived unit are designed and synthesized. The relationships between chemical structure and optoelectronic properties of the polymers are systematically investigated.The control of UV-Vis absorption spectra and energy levels in resulting polymers are achieved by introducing suitable pended acceptor units. The photovoltaic properties of the resulting polymers are evaluated by blending the polymers with(6,6)-phenyl-C71-butyric acid methyl ester. The resulting solar cells exhibit moderate performances with high open-circuit voltage. Charge transport properties and morphology were investigated to understand the performance of corresponding solar cells.

  2. Dominant intrinsic acceptors in GaN and ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Saarinen, K; Hautakangas, S; Tuomisto, F [Laboratory of Physics, Helsinki University of Technology, PO Box 1100, FI-02015 TKK (Finland)

    2006-09-01

    Positron annihilation measurements reveal negatively charged Ga vacancies in n-type GaN and Zn vacancies in n-type ZnO. Positron trapping at other negative defects is not observed, indicating that cation vacancies are the dominant acceptors in these materials. The vacancy concentrations are the same as the total acceptor densities determined in Hall experiments, confirming the dominant role of the vacancy defects. The Ga vacancy in GaN is found as the main compensating centre over the range of four orders of magnitude of intentional oxygen doping.

  3. Dominant intrinsic acceptors in GaN and ZnO

    International Nuclear Information System (INIS)

    Saarinen, K; Hautakangas, S; Tuomisto, F

    2006-01-01

    Positron annihilation measurements reveal negatively charged Ga vacancies in n-type GaN and Zn vacancies in n-type ZnO. Positron trapping at other negative defects is not observed, indicating that cation vacancies are the dominant acceptors in these materials. The vacancy concentrations are the same as the total acceptor densities determined in Hall experiments, confirming the dominant role of the vacancy defects. The Ga vacancy in GaN is found as the main compensating centre over the range of four orders of magnitude of intentional oxygen doping

  4. LECTURE CANCELLED - “The power of collaboration - innovating collaborative relationships" by Michael Kimmel | 8 March

    CERN Multimedia

    2013-01-01

    PLEASE NOTE THAT THIS LECTURE IS CANCELLED Friday, 8 March -  from 11.30 a.m. to 1 p.m. Globe of Science and Innovation Route de Meyrin, 1211 Geneva International Women’s Day Conference Lecture will be in English - Interpreting available in French Limited number of seats - registration is essential Reservation: + 41 22 767 76 76 or cern.reception@cern.ch Dr. Michael Kimmel, a renowned sociologist and an expert on male-female relationships, will share his latest findings on gender collaboration and how it can lead to innovation and improved relationships both at work and in the world outside. Michael Kimmel is among the world’s leading experts on male-female relationships. A Professor of Sociology at the State University of New York at Stony Brook, he is the author or editor of more than 20 books on the topic. He consults corporations, NGOs and public sector organisations all over the world on gender equity issues, including work-family balance, reducing workplac...

  5. Michael Polanyi and his generation origins of the social construction of science

    CERN Document Server

    Nye, Mary Jo

    2011-01-01

    In Michael Polanyi and His Generation, Mary Jo Nye investigates the role that Michael Polanyi and several of his contemporaries played in the emergence of the social turn in the philosophy of science. This turn involved seeing science as a socially based enterprise that does not rely on empiricism and reason alone but on social communities, behavioral norms, and personal commitments. Nye argues that the roots of the social turn are to be found in the scientific culture and political events of Europe in the 1930s, when scientific intellectuals struggled to defend the universal status of scientific knowledge and to justify public support for science in an era of economic catastrophe, Stalinism and Fascism, and increased demands for applications of science to industry and social welfare. At the center of this struggle was Polanyi, who Nye contends was one of the first advocates of this new conception of science. Nye reconstructs Polanyi’s scientific and political milieus in Budapest, Berlin, and Manchester f...

  6. Production of Low-Freezing-Point Highly Branched Alkanes through Michael Addition.

    Science.gov (United States)

    Jing, Yaxuan; Xia, Qineng; Liu, Xiaohui; Wang, Yanqin

    2017-12-22

    A new approach for the production of low-freezing-point, high-quality fuels from lignocellulose-derived molecules was developed with Michael addition as the key step. Among the investigated catalysts, CoCl 2 ⋅6 H 2 O was found most active for the Michael addition of 2,4-pentanedione with FA (single aldol adduct of furfural and acetone, 4-(2-furanyl)-3-butene-2-one). Over CoCl 2 ⋅6 H 2 O, a high carbon yield of C 13 oxygenates (about 75 %) can be achieved under mild conditions (353 K, 20 h). After hydrodeoxygenation, low-freezing-point (hydrodeoxygenation, high density (0.8415 g mL -1 ) and low-freezing-point (<223 K) branched alkanes with 18, 23 carbons within lubricant range were also obtained over a Pd/NbOPO 4 catalyst. These highly branched alkanes can be directly used as transportation fuels or additives. This work opens a new strategy for the synthesis of highly branched alkanes with low freezing point from renewable biomass. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Adapting Shakespeare – Converting Shylock in Michael Radford’s the Merchant of Venice

    Directory of Open Access Journals (Sweden)

    Oakes Luke

    2016-08-01

    Full Text Available This article aims to explore the extension and evolution of Shakespeare’s The Merchant of Venice through Michael Radford’s 2004 cinematic adaptation. By investigating the concept of adaptation and the significance of intertextuality, Shakespeare’s source text is considered alongside Radford’s twenty-first century recreation to reimagine and redefine the construction of Shylock as both a comic and tragic device utilized across film and play. Issues of racial and religious prejudices alongside anti- Semitic views were particularly prominent in Elizabethan England and, by concentrating on recontextualisation, this article looks to expose Shakespeare’s characterization as a reflective commentary concerning societal discriminations at the time of the play’s performance. By focusing primarily on Shakespeare’s Jewish Usurer, Radford is able to reconstruct and reestablish the dramatic devices and characters within the cinematic version, metaphorically converting Shylock from comic villain to tragic victim. Finally, it argues that this dynamic shift inevitably metamorphoses Shylock from a spectator’s perspective and provides Michael Radford with an opportunity to offer a social commentary on social inequality in the twenty-first century.

  8. 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

  9. Ex-situ activation of magnesium acceptors in InGaN/LED-structures

    Energy Technology Data Exchange (ETDEWEB)

    Kusch, Gunnar; Frentrup, Martin; Stellmach, Joachim; Kolbe, Tim; Wernicke, Tim; Pristovsek, Markus; Kneissl, Michael [Technische Universitaet Berlin, Institut fuer Festkoerperphysik, Hardenbergstr. 36, 10623 Berlin (Germany)

    2011-07-01

    One of the main problems limiting the output power of group-III-nitride compound light emitting diodes (LEDs) and laser diodes (LD) is the p-doping of nitrides with magnesium (Mg). During metal-organic vapor phase epitaxy (MOVPE) growth of (Al)GaN:Mg magnesium acceptors are passivated by hydrogen (H). By thermal annealing under nitrogen atmosphere the Mg-H bond can be cracked, thus activating the Mg acceptor. We have investigated ex-situ Mg-activation of the p-GaN layer and p-AlGaN electron blocking layer (EBL) in LEDs grown by MOVPE. Especially the activation of the AlGaN EBL is crucial. Simulations show, that a high doping level is required for effective electron blocking and a high injection efficiency. Additionally the acceptor activation energy is expected to increase with increasing Al-content, reducing the free hole concentration in the EBL. Electroluminescence spectroscopy (EL) was performed to determine the influence of the activation on the external quantum efficiency of the LED structure. Furthermore we used CV measurements to determine the Mg-acceptor concentration.

  10. Quantitative measurements of magnetic polaron binding on acceptors in CdMnTe alloys

    Science.gov (United States)

    Nhung, Tran Hong; Planel, R.

    1983-03-01

    The acceptor binding energy is measured as a function of Temperature and composition in Cd1-x Mnx Te alloys, by time resolved spectroscopy. The Bound magnetic polaron effect is measured and compared with a theory accouting for magnetic saturation and fluctuations.

  11. Discriminating a deep defect from shallow acceptors in supercell calculations: gallium antisite in GaAs

    Science.gov (United States)

    Schultz, Peter

    To make reliable first principles predictions of defect energies in semiconductors, it is crucial to discriminate between effective-mass-like defects--for which existing supercell methods fail--and deep defects--for which density functional theory calculations can yield reliable predictions of defect energy levels. The gallium antisite GaAs is often associated with the 78/203 meV shallow double acceptor in Ga-rich gallium arsenide. Within a framework of level occupation patterns, analyses of structure and spin stabilization can be used within a supercell approach to distinguish localized deep defect states from shallow acceptors such as BAs. This systematic analysis determines that the gallium antisite is inconsistent with a shallow state, and cannot be the 78/203 shallow double acceptor. The properties of the Ga antisite in GaAs are described, predicting that the Ga antisite is a deep double acceptor and has two donor states, one of which might be accidentally shallow. -- Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  12. Limited Cash Flow on Slot Machines: Effects of Prohibition of Note Acceptors on Adolescent Gambling Behaviour

    Science.gov (United States)

    Hansen, Marianne; Rossow, Ingeborg

    2010-01-01

    This study addresses the impact of prohibition of note acceptors on gambling behaviour and gambling problems among Norwegian adolescents. Data comprised school surveys at three time points; 2004 and 2005 (before intervention) and 2006 (after intervention). Net samples comprised 20.000 students aged 13-19 years at each data collection. Identical…

  13. 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...

  14. On the Molecular Origin of Charge Separation at the Donor-Acceptor Interface

    KAUST Repository

    Sini, Gjergji

    2018-01-22

    Fullerene-based acceptors have dominated organic solar cells for almost two decades. It is only within the last few years that alternative acceptors rival their dominance, introducing much more flexibility in the optoelectronic properties of these material blends. However, a fundamental physical understanding of the processes that drive charge separation at organic heterojunctions is still missing, but urgently needed to direct further material improvements. Here a combined experimental and theoretical approach is used to understand the intimate mechanisms by which molecular structure contributes to exciton dissociation, charge separation, and charge recombination at the donor–acceptor (D–A) interface. Model systems comprised of polythiophene-based donor and rylene diimide-based acceptor polymers are used and a detailed density functional theory (DFT) investigation is performed. The results point to the roles that geometric deformations and direct-contact intermolecular polarization play in establishing a driving force (energy gradient) for the optoelectronic processes taking place at the interface. A substantial impact for this driving force is found to stem from polymer deformations at the interface, a finding that can clearly lead to new design approaches in the development of the next generation of conjugated polymers and small molecules.

  15. 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

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

    KAUST Repository

    Holliday, Sarah; Ashraf, Raja Shahid; Nielsen, Christian Bergenstof; Kirkus, Mindaugas; Rö hr, Jason A.; Tan, Chinghong; Collado-Fregoso, Elisa; Knall, Astrid Caroline; Durrant, James R.; Nelson, Jenny K.; McCulloch, Iain

    2015-01-01

    3HT: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

  17. Tailored Band Gaps in Sulfur- and Nitrogen-Containing Porous Donor-Acceptor Polymers

    Czech Academy of Sciences Publication Activity Database

    Schwarz, D.; Kochergin, Y. S.; Acharjya, A.; Ichangi, Arun; Opanasenko, Maksym; Čejka, Jiří; Lappan, U.; Arki, P.; He, J.; Schmidt, J.; Nachtigall, P.; Thomas, A.; Tarábek, Ján; Bojdys, Michael J.

    2017-01-01

    Roč. 23, č. 53 (2017), s. 13023-13027 ISSN 0947-6539 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : conjugated microporous polymers * donor-acceptor dyads * photocatalysis * sulfur * triazine Subject RIV: CC - Organic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Organic chemistry; Physical chemistry (UFCH-W) Impact factor: 5.317, year: 2016

  18. Photoluminescence quenching through resonant energy transfer in blends of conjugated polymer with low-molecular acceptor

    International Nuclear Information System (INIS)

    Zapunidi, S. A.; Paraschuk, D. Yu.

    2008-01-01

    A model is proposed for photoluminescence quenching due to resonant energy transfer in a blend of a conjugated polymer and a low-molecular energy acceptor. An analytical dependence of the normalized photoluminescence intensity on the acceptor concentration is derived for the case of a homogeneous blend. This dependence can be described by two fitting parameters related to the Foerster radii for energy transfer between conjugated segments of the polymer and between the conjugated polymer segment and the energy acceptor. Asymptotic approximations are obtained for the model dependence that make it possible to estimate the contribution from the spatial migration of excitons to the photoluminescence quenching. The proposed model is used to analyze experimental data on the photoluminescence quenching in a blend of the soluble derivative of poly(p-phenylene vinylene) and trinitrofluorenone [13]. The Foerster radius for resonant energy transfer between the characteristic conjugated segment of poly(p-phenylene vinylene) and the energy acceptor is determined to be r F = 2.6 ± 0.3 nm

  19. 2004 Electron Donor Acceptor Interactions Gordon Conference - August 8-13, 2004

    Energy Technology Data Exchange (ETDEWEB)

    GUILFORD JONES; S ST

    2005-09-14

    The 2004 Gordon Conference on Donor/Acceptor Interactions will take place at Salve Regina University in Newport, Rhode Island on August 8-13, 2004. The conference will be devoted to the consequences of charge interaction and charge motion in molecular and materials systems.

  20. Donor-acceptor properties of a single-molecule altered by on-surface complex formation

    Czech Academy of Sciences Publication Activity Database

    Meier, T.; Pawlak, R.; Kawai, S.; Geng, Y.; Liu, X.; Decurtins, S.; Hapala, Prokop; Baratoff, A.; Liu, S.X.; Jelínek, Pavel; Meyer, E.; Glatzel, T.

    2017-01-01

    Roč. 11, č. 8 (2017), s. 8413-8420 ISSN 1936-0851 R&D Projects: GA ČR GB14-37427G Institutional support: RVO:68378271 Keywords : nc AFM * DFT * acceptor donor Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 13.942, year: 2016

  1. Optimum energy levels and offsets for organic donor/acceptor binary photovoltaic materials and solar cells

    International Nuclear Information System (INIS)

    Sun, S.-S.

    2005-01-01

    Optimum frontier orbital energy levels and offsets of an organic donor/acceptor binary type photovoltaic material have been analyzed using classic Marcus electron transfer theory in order to achieve the most efficient photo induced charge separation. This study reveals that, an exciton quenching parameter (EQP) yields one optimum donor/acceptor frontier orbital energy offset that equals the sum of the exciton binding energy and the charge separation reorganization energy, where the photo generated excitons are converted into charges most efficiently. A recombination quenching parameter (RQP) yields a second optimum donor/acceptor energy offset where the ratio of charge separation rate constant over charge recombination rate constant becomes largest. It is desirable that the maximum RQP is coincidence or close to the maximum EQP. A third energy offset is also identified where charge recombination becomes most severe. It is desirable that the most severe charge recombination offset is far away from maximum EQP offset. These findings are very critical for evaluating and fine tuning frontier orbital energy levels of a donor/acceptor pair in order to realize high efficiency organic photovoltaic materials

  2. Electron Transfer in Donor-Bridge-Acceptor Systems and Derived Materials

    NARCIS (Netherlands)

    Oosterbaan, W.D.

    2002-01-01

    Some aspects of photoinduced electron transfer (ET) in (electron donor)-bridge-(electron acceptor) compounds (D-B-A) and derived materials are investigated. Aim I is to determine how and to which extent non-conjugated double bonds in an otherwise saturated hydrocarbon bridge affect the rate of

  3. 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.

  4. Highly efficient exciplex organic light-emitting diodes incorporating a heptazine derivative as an electron acceptor.

    Science.gov (United States)

    Li, Jie; Nomura, Hiroko; Miyazaki, Hiroshi; Adachi, Chihaya

    2014-06-11

    Highly efficient exciplex systems incorporating a heptazine derivative () as an electron acceptor and 1,3-di(9H-carbazol-9-yl)benzene () as an electron donor are developed. An organic light-emitting diode containing 8 wt% : as an emitting layer exhibits a maximum external quantum efficiency of 11.3%.

  5. Adsorption of Organic Electron Acceptors on Graphene-like Molecules: Quantum Chemical and Molecular Mechanical Study

    Czech Academy of Sciences Publication Activity Database

    Haldar, Susanta; Kolář, Michal; Sedlák, Robert; Hobza, Pavel

    2012-01-01

    Roč. 116, č. 48 (2012), s. 25328-25336 ISSN 1932-7447 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : graphene * organic electron acceptors * interaction energies * base-pairs * hydrophobic association Subject RIV: CF - Physical ; The oretical Chemistry Impact factor: 4.814, year: 2012

  6. Novel indole-based inhibitors of IMPDH: introduction of hydrogen bond acceptors at indole C-3.

    Science.gov (United States)

    Watterson, Scott H; Dhar, T G Murali; Ballentine, Shelley K; Shen, Zhongqi; Barrish, Joel C; Cheney, Daniel; Fleener, Catherine A; Rouleau, Katherine A; Townsend, Robert; Hollenbaugh, Diane L; Iwanowicz, Edwin J

    2003-04-07

    The development of a series of novel indole-based inhibitors of 5'-inosine monophosphate dehydrogenase (IMPDH) is described. Various hydrogen bond acceptors at C-3 of the indole were explored. The synthesis and the structure-activity relationships (SARs) derived from in vitro studies are outlined.

  7. 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…

  8. Nano-scale control of energy transfer in the system 'donor-acceptor'

    International Nuclear Information System (INIS)

    Malyukin, Yu.V.; Yefimova, S.L.; Lebedenko, A.N.; Sorokin, A.V.; Borovoy, I.A.

    2005-01-01

    Fluorescence resonance energy transfer (FRET) in a cascade scheme between three amphiphilic dyes 3,3'-dioctadecyloxacarbocyanine perchlorate (DiOC 18 (3), donor), 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiIC 18 (3), acceptor/donor) and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine perchlorate (DiIC 18 (5), acceptor) has been investigated at low dye concentration (10 -5 mol/l) in water-micellar solutions due to a forced assembling of dyes in nanoscale volume. The experimental data have revealed that sodium dodecyl sulfate (SDS) micelles solubilize dye molecules such that their hydrophilic heads are in contact with water, while hydrophobic tails are embedded into the hydrocarbon core of the micelle. FRET efficiency has been found to depend on the concentration of dyes in micelles and the most effective when each SDS micelle contains 1 donor (DiOC 18 (3)), 2 acceptor/donor (DiIC 18 (3)) and 4 acceptor (DiIC 18 (5)) molecules

  9. Organic charge transfer phase formation in thin films of the BEDT-TTF/TCNQ donor-acceptor system

    DEFF Research Database (Denmark)

    Solovyeva, Vita; Keller, K.; Huth, M.

    2009-01-01

    We have performed charge transfer phase formation studies on the donor/acceptor system bis-(ethylendithio)tetrathiafulvalene (BEDT-TTF)/tetracyanoquinodimethane,(TCNQ) by means of physical vapor deposition. We prepared donor/acceptor bilayer structures on glass and Si(100)/SiO substrates held...

  10. Study of microbial perchlorate reduction: Considering of multiple pH, electron acceptors and donors

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xing [Key Laboratory of Water Pollution Control and Recycling (Shandong), School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Gao, Baoyu, E-mail: bygao@sdu.edu.cn [Key Laboratory of Water Pollution Control and Recycling (Shandong), School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Jin, Bo [School of Chemical Engineering, The University of Adelaide, Adelaide SA 5005,Australia (Australia); Zhen, Hu [Key Laboratory of Water Pollution Control and Recycling (Shandong), School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Wang, Xiaoyi [CSIRO Land and Water, Gate 5, Waite Road, Urrbrae, SA 5064 (Australia); Dai, Ming [School of Chemical Engineering, The University of Adelaide, Adelaide SA 5005,Australia (Australia)

    2015-03-21

    Graphical abstract: Schemes of perchlorate reduction in ClO{sub 4}{sup −}/ClO{sub 3}{sup −}–NO{sub 3}{sup −} e{sup −}acceptor systems. - Highlights: • We created a multiple electron acceptor/donor system for ClO{sub 4}{sup −} reduction. • Nitrate reduction was inhibited when using perchlorate-grown Azospira sp. KJ. • Reduction proceeded as an order of ClO{sub 3}{sup −}, ClO{sub 4}{sup −}and NO{sub 3}{sup −}. • Oxidation of acetate was inhibited by succinate in acetate–succinate series. - Abstract: Bioremediation of perchlorate-cotaminated water by a heterotrophic perchlorate reducing bacterium creates a multiple electron acceptor-donor system. We experimentally determined the perchlorate reduction by Azospira sp. KJ at multiple pH, electron acceptors and donors systems; this was the aim of this study. Perchlorate reduction was drastically inhibited at the pH 6.0, and the maximum reduction of perchlorate by Azospira sp. KJ was observed at pH value of 8.0. Perchlorate reduction was retarded in ClO{sub 4}{sup −}–ClO{sub 3}{sup −}, ClO{sub 4}{sup −}–ClO{sub 3}{sup −}–NO{sub 3}{sup −},and ClO{sub 4}{sup −}–NO{sub 3}{sup −} acceptor systems, while being completely inhibited by the additional O{sub 2} in the ClO{sub 4}{sup −}–O{sub 2} acceptor system. The reduction proceeded as an order of ClO{sub 3}{sup −}, ClO{sub 4}{sup −}, and NO{sub 3}{sup −} in the ClO{sub 4}{sup −}–ClO{sub 3}{sup −}–NO{sub 3}{sup −} system. K{sub S,}v{sub max}, and q{sub max} obtained at different e{sup −} acceptor and donor conditions are calculated as 140.5–190.6 mg/L, 8.7–13.2 mg-perchlorate/L-h, and 0.094–0.16 mg-perchlorate/mg-DW-h, respectively.

  11. 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

  12. Cuestión de tiempo: Michael Fried y el tiempo del arte moderno A matter of time: Michael Fried and modernist art the time of modernist art

    Directory of Open Access Journals (Sweden)

    David Díaz Soto

    2011-07-01

    Full Text Available En el siglo XIX, autores fundacionales del formalismo, como Fiedler o Hildebrand, contrapusieron estrictamente las artes plásticas, «puramente visuales», a las artes verbales del discurso, proscribiéndoles la narración y disociándolas de la temporalidad: se trata del «principio de exclusión del tiempo», vinculado al formalismo. Más tarde, el crítico «modernista» de arte Clement Greenberg planteó la instantaneidad, en tanto que opuesta a la duración, como modalidad ideal de la experiencia artística. Pero el historiador y crítico de arte Michael Fried, en sus textos de los años 60 sobre arte abstracto, se distancia de Greenberg, desarrollando un discurso sobre la temporalidad en las artes plásticas, con nociones como «tiempo visual»; y en sus posteriores textos historiográficos investiga las modalidades temporales de la representación pictórica. La aparente paradoja entre la crítica de Fried a la hipóstasis «literalista» de la duración en las tardovanguardias y el papel crucial que concede a Manet y a la instantaneidad en el origen del arte moderno, la resolveremos atendiendo a su reivindicación de la temporalidad durativa de «lo cotidiano». Así cabe comprender la concepción de la modalidad temporal característica de la modernidad y del arte moderno, a la que apunta su noción teórica de presentness.In the nineteenth century, seminal authors of Formalism, like Fiedler or Hildebrand, strictly compared the «purely visual» plastic arts to the discursive arts of verbal language, ruling out narrativity from plastic arts, which they dissociated from temporality - the formalist «principle of exclusion of time». Later on, «modernist» art critic Clement Greenberg claimed that instantaneousness, as opposed to duration, was the ideal modality for artistic experience. Art critic and historian Michael Fried did not share Greenberg's position, but developed instead a discourse about time in plastic arts. In his early

  13. Effect of deviation from stoichiometry on the nature of shallow acceptor states in CdTe crystals

    International Nuclear Information System (INIS)

    Agrinskaya, N.V.; Shashkova, V.V.

    1988-01-01

    Photoconductivity and photoluminescence spectra in the region of donor-acceptor recombination of pure CdTe crystals, grown under conditions of different deviations from stoichiometry are investigated. It is shown that the predominant type of minor acceptors in n-type crystals (with Cd excess) differs from acceptors in p-type crystals (with Te excess). Residual acceptors replacing Te(P, As) prevail in n-type crystals and acceptors replacing Cd(Li, Na) prevail in p-type crystals. As a result of p-type crystal annealing a change of the type of prevailing aceptors accurs in Cd pairs (bands linked with P, As prevail) which testifies to the residual impurity reconstruction in Cd and Te sublattices

  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.; Risko, Chad; Aziz, Saadullah Gary; Da Silva Filho, Demé trio A Da Silva; Bredas, Jean-Luc

    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. 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.

  16. N-Heterocyclic Carbene-Catalysed Diastereoselective Vinylogous Michael Addition Reaction of gamma-Substituted deconjugated Butenolides

    KAUST Repository

    Guo, Hao; Xing, Fen; Du, Guang-Fen; Huang, Kuo-Wei; Dai, Bin; He, Lin

    2015-01-01

    An efficient N-heterocyclic carbene (NHC)-catalysed vinylogous Michael addition of deconjugated butenolides was developed. In the presence of 5 mol% of the NHC catalyst, both γ-alkyl and aryl-substituted deconjugated butenolides undergo vinylogous Michael addition with various α, β-unsaturated ketones, esters, or nitriles to afford γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary carbon centers in good to excellent yields with excellent diastereoselectivities. In this process, the free carbene is assumed to act as a strong Brønsted base to promote the conjugate addition.

  17. N-Heterocyclic Carbene-Catalysed Diastereoselective Vinylogous Michael Addition Reaction of gamma-Substituted deconjugated Butenolides

    KAUST Repository

    Guo, Hao

    2015-11-16

    An efficient N-heterocyclic carbene (NHC)-catalysed vinylogous Michael addition of deconjugated butenolides was developed. In the presence of 5 mol% of the NHC catalyst, both γ-alkyl and aryl-substituted deconjugated butenolides undergo vinylogous Michael addition with various α, β-unsaturated ketones, esters, or nitriles to afford γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary carbon centers in good to excellent yields with excellent diastereoselectivities. In this process, the free carbene is assumed to act as a strong Brønsted base to promote the conjugate addition.

  18. Enantio- and Stereoselective Construction of Atisane Scaffold via Organocatalytic Intramolecular Michael Reaction and Diels-Alder Reaction.

    Science.gov (United States)

    Sekita, Hiroko; Adachi, Kyohei; Kobayashi, Ippei; Sato, Yusuke; Nakada, Masahisa

    2017-05-05

    An enantio- and stereoselective construction of the atisane scaffold via organocatalytic intramolecular Michael reaction and Diels-Alder reaction is described. The organocatalytic intramolecular Michael reaction has been found to stereoselectively generate a trans-stereodiad comprising an all-carbon quaternary and a tertiary stereogenic centers. Use of the chiral secondary amine bearing thiourea with benzoic acid as additive is the key to obtaining the desired product with excellent ee in synthetically acceptable yield. The prepared chiral building block has been successfully converted to the compound including the atisane scaffold via the highly stereoselective intramolecular Diels-Alder reaction.

  19. Las relaciones entre la Iglesia y el Estado en la teoría de la justicia de Michael Walzer

    OpenAIRE

    Roldán, Alberto Fernando

    2009-01-01

    Roldan, A. F. (2009). Las relaciones entre la Iglesia y el Estado en la teoría de la justicia de Michael Walzer (Tesis de Maestría). Universidad Nacional de Quilmes, Bernal, Argentina. En la presente tesis, se discuten las relaciones entre la Iglesia –término que se utiliza no en el sentido confesional sino en tanto institución religiosa- y el Estado moderno. Se escoge como marco teórico la filosofía política del pensador judío americano Michael Walzer, exponente del “comunitarismo”, un...

  20. Michael Fordham and the Journal of Analytical Psychology: the view from Hangman's Hill.

    Science.gov (United States)

    Urban, Elizabeth

    2015-09-01

    This short paper was presented to a conference in honour of the 60(th) year of the JAP and was one of others that acknowledged the contribution of Michael Fordham. The subtitle refers to the paper's overview of Fordham's published oeuvre and the particular place of the Journal of Analytical Psychology, for which he was the founding editor. Fordham's contribution to a Jungian-based model of development is discussed, with reference to his papers in the British Journal of Medical Psychology. The paper notes miscellaneous pieces from Fordham's commentaries, obituaries, papers and reviews which capture not only the development of Fordham as a thinker but also his character. There is discussion of his reviews of Melanie Klein's Envy and Gratitude and manuscripts by Erich Neumann. A reminiscence of Fordham as supervisor is recounted. © 2015, The Society of Analytical Psychology.

  1. Lizards, ticks and contributions to Australian parasitology: C. Michael Bull (1947-2016).

    Science.gov (United States)

    Godfrey, Stephanie S; Gardner, Michael G

    2017-12-01

    Professor C. Michael Bull was a great scientist and mentor, and an Associate Editor of this journal. While his research career spanned the fields of behavioural ecology, conservation biology and herpetology, in this article, we pay tribute to his major contribution to Australian parasitology. Mike authored more than eighty articles on host-parasite ecology, and revealed major insights into the biology and ecology of ticks from his long term study of the parapatric boundary of two tick species ( Amblyomma limbatum and Bothriocroton hydrosauri ) on the sleepy lizard ( Tiliqua rugosa ). In this article, we provide an overview of how this research journey developed to become one of the longest-running studies of lizards and their ticks, totalling 35 years of continuous surveys of ticks on lizards, and the insights and knowledge that he generated along that journey.

  2. A History of Experiences and Thinking Men. The History of Political Thought according to Michael Oakeshott

    Directory of Open Access Journals (Sweden)

    Spartaco Pupo

    2014-12-01

    Full Text Available Michael Oakeshott conceives the history of European political thought as a structuring of ideas and arguments of the practical experience aimed to understanding political expressions in vogue in the culture of a people. It is not a continuous and cumulative history of abstract and disembodied ideas, as it is wrongly conceived, but of some men who thought politics in a certain way on the basis of the language and of the set of actions, moral beliefs and contingencies of the people which they belong to. The article highlights the comparison between Oakeshott, Quentin Skinner and Gianfranco Miglio on the search for the most appropriate method to be applied in the study of the history of political thought.

  3. 'Introducing Michael Gove to Loïc Wacquant': Why Social Work Needs Critical Sociology.

    Science.gov (United States)

    Michael Garrett, Paul

    2016-06-01

    In 2013, Michael Gove, then Secretary of State for Education and Health in the UK coalition government, criticised social workers for laying insufficient emphasis on the 'agency' of individuals and for being too preoccupied with social and economic inequalities. Such a perspective, which is not unique to Gove, needs to be countered by reaffirming the significance of an expansively critical sociology for social work. In this context, the thematic concerns of the French theorist, Loïc Wacquant, illuminates key aspects of social work engagement with clients which Gove and his ideological associates appear intent on ignoring. The issues raised have significant political resonances given the pending UK General Election taking place in May 2015.

  4. Modalities of representation and perception in Michael Ondaatje’s Anil’s Ghost

    Directory of Open Access Journals (Sweden)

    Sigrid Renaux

    2017-01-01

    Full Text Available http://dx.doi.org/10.5007/2175-8026.2017v70n1p113 This study analyses the way in which the interdependence of the representation and perception of reality is exemplified and questioned in Michael Ondaatje’s Anil’s Ghost (2000. As we enter this work of resistance literature by way of an omniscient narrator, we enter not just the geographical spaces and cultural history of Sri Lanka, but find ourselves taking part in the daily struggle of the people to survive, to identify and do justice to the many dead in this conflict between ethnic groups and the government. This fragmentation of the narrative structure – casting doubt on the conflicting relationships established between the characters’ present and the past, between western and eastern values in relation to the concept of truth, the search for lost identity and love – highlights still further the interchangeability of representation and perception of reality.

  5. Michael Oakeshott´s Work as a Liberal-Conserv ative Paradigm

    Directory of Open Access Journals (Sweden)

    Josep Baqués

    2014-01-01

    Full Text Available As is the case with other thinkers linked to what can be broadly defined as conservatism, it is arguable whether Michael Oakeshott was just a conservative, or whether he was also a liberal. He often rejected this last label. He also tried to avoid the classic debate between the left/right wing divide, conferring instead a mantle of neutrality on his work. This analysis shows, on the one hand, that Oakeshott´s work is ideologically orientated and, on the other hand, that it contains a substantial liberal component. In fact, he offered a liberal-conservative synthesis in which the free market appears to be not only the best, but the only feasible outcome in the proposed scenario of political prudence. I will fi rst connect Oakeshott with the main traditions of thought, then analyse the theoretical implications of his position, and finally explore the consequences derived from all this for everyday political practice.

  6. The role of Michael Pupin in solving of Serbian national question

    Directory of Open Access Journals (Sweden)

    Grčić Mirko D.

    2004-01-01

    Full Text Available Michael I. Pupin was a professor at the University of Columbia, member and the president of Academy of Science in New York; one of the esteemed members of USA National Academy of Science; member and president of many experts and scientific institutions and societies in the USA; member of State Council for Scientific Research by president of the USA during the World War I. Of the great importance for political geography and geopolitics was his activity in Paris during the Peace Conference after the World War I in 1919 also as his great contribution to establishment of state borders of Kingdom of Serbs, Croats and Slovenians (later Yugoslavia, which helped those nations to establish their national borders at maximum level. Pupin claimed that he was Yugoslav patriot and American citizen. Role of M. Pupin in battle for national interests and Yugoslav borders after the World War I is shown in this article.

  7. Rationalism and traditionalism in politics. The correspondence between Karl R. Popper and Michael Oakeshott

    Directory of Open Access Journals (Sweden)

    Spartaco Pupo

    2016-07-01

    Full Text Available The correspondence of 1948 between Karl Popper and Michael Oakeshott, translated for the first time in Italian and published in the appendix to this paper, demonstrates the existence of two different ways of thinking about politics: the rationalist approach, founded on the “argumentation” as a rational means for the non-violent solution of problems (Popper, and the traditionalist mode, inspired by the method of “conversation” as a guarantee of constant openness to the diversity of identities (Oakeshott. To rise from the letters is a mutual influence on the interpretation of the key concepts that characterize the thought of the two authors, which however does not cancel the fundamental divergence of their political orientation.

  8. Inverting the diastereoselectivity of the mukaiyama-michael addition with graphite-based catalysts

    KAUST Repository

    Acocella, Maria Rosaria

    2014-02-07

    Here, we show that graphite-based catalysts, mainly graphite oxide (GO) and exfoliated GO, are effective recyclable catalysts for a relevant stereoselective Mukaiyama-Michael addition, outperforming currently available catalysts. Moreover, the graphite-based catalysts described here invert the diastereoselectivity relative to that observed with known catalysts, with the unprecedented large prevalence of the anti diastereoisomer. This inverted diastereoselectivity is increased when the catalyst concentration is reduced and after catalyst recycling. Density functional theory calculations suggest that the selectivity is determined by two types of supramolecular interactions operating between the catalyst and the substrates at the diastereoselectivity- determining transition state, specifically, the π-stacking of b-nitrostyrene with graphite and the van der Waals interaction between the SiMe3 group of the silyl ether and the graphite. © 2013 American Chemical Society.

  9. "Alarme de incêndio": Michael Löwy e a crítica ecossocialista da civilização capitalista moderna "Fire alarm": Michael Löwy and the ecosocialist critique of the modern capitalist civilization

    Directory of Open Access Journals (Sweden)

    Fabio Mascaro Querido

    2013-04-01

    Full Text Available A emergência da crise ecológica, como sintoma mais nítido de uma verdadeira crise civilizató-ria, impôs novos desafios ao pensamento crítico e, em especial, ao marxismo. Partindo desse pressuposto, o objetivo deste artigo é apresentar a defesa de Michael Löwy de uma radicalização ecossocialista da crítica marxista da modernidade, tarefa para a qual a grande recusa de Walter Benjamin das ideologias do pro- gresso é uma das fontes decisivas de inspiração. Para Michael Löwy, a ruptura com as ideologias do progresso e com o paradigma civilizatório capitalista moderno é uma condição indispensável para a atua-lização ecossocialista do marxismo.The emergence of the ecological crisis as a clearer symptom of a true civilizatory crisis has imposed new challenges to critical thought and, in particular, to Marxism. Based on this assumption, this article aims to present Michael Löwy's defense of an ecosocialist radicalization of the Marxist critique of modernity, a task for which Walter Benjamin's great refusal of the ideologies of progress is one of the critical sources of inspiration. To Michael Löwy, breaking away from the ideologies of progress and from the modern capitalistic civilizatory paradigm is a prerequisite for the ecosocialist updating of Marxism.

  10. Michael Novak's "Business as a Calling" as a Vehicle for Addressing Ethical and Policy Concerns in a Business Law Course

    Science.gov (United States)

    Murphy, Tonia Hap

    2008-01-01

    This article describes the author's experience of incorporating Michael Novak's "Business as a Calling: Work and the Examined Life" into a Business Law course. The author views it as a positive addition to the course, one that may be of interest to her colleagues at other institutions. Accordingly, after an overview of Novak's analysis in…

  11. N-Heterocyclic-Carbene-Catalysed Diastereoselective Vinylogous Mukaiyama/Michael Reaction of 2-(Trimethylsilyloxy)furan and Enones

    KAUST Repository

    Wang, Ying; Du, Guang Fen; Xing, Fen; Huang, Kuo-Wei; Dai, Bin; He, Lin

    2015-01-01

    N-heterocyclic carbenes have been utilised as highly efficient nucleophilic organocatalysts to mediate vinylogous Mukaiyama/Michael reactions of 2-(trimethylsilyloxy)furan with enones to afford γ-substituted butenolides in 44-99% yield with 3:1-32:1 diastereoselectivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Komparativistlikke ja kultuuriteaduslikke ärgitusi Baltimaade germanistikale / Michael Schwidtal ; saksa keelest tõlkinud Vahur Aabrams

    Index Scriptorium Estoniae

    Schwidtal, Michael

    2001-01-01

    3. - 5. sept. 2001 toimus Riias sümpoosion "Unter diesem braunen Himmel. Jakob Michael Reinhold Lenz und die deutsche Literatur des Baltikums", 7. - 9. sept. Tartus "Torm ja tung Liivimaal. Mässu mudelid", pühendatud J. M. R. Lenzi ja Kristian Jaak Petersoni loomingule. Ülevaade

  13. A Symposium on the Relevance of Michael Polanyi's Insights to a Reformulated Understanding of Science, Technology, and Society

    Science.gov (United States)

    Mead, Walter B.

    2011-01-01

    This is intended as an introductory statement to the explorations undertaken in the essays that follow. The authors of these essays attempt to introduce the reader to some of the insights of Michael Polanyi and their implications for the reader who wishes to come to a greater understanding of modern technological society, which--for better or…

  14. Jack Michael's Musings on the 60th Anniversary of Skinner's "Verbal Behavior"

    Science.gov (United States)

    Esch, Barbara E.; Esch, John W.; Palmer, David C.

    2017-01-01

    When the B. F. Skinner Foundation reprinted Skinner's "Verbal Behavior" in 1992, Jack Michael wrote one of its two forewords, a detailed outline of the book's purpose and scope. On the 60th anniversary of the first publication (1957) of "Verbal Behavior", Jack reflects on the book's impact and its importance to the…

  15. What I Think I May Have Learned--Reflections on 50 Years of Teaching: An Interview with Michael Wertheimer

    Science.gov (United States)

    Michael, Kurt D.

    2006-01-01

    Kurt Michael is an associate professor in the Department of Psychology at Appalachian State University (ASU) where he teaches history and systems of psychology, abnormal psychology, child psychopathology, and interventions for children and adolescents. He received his BA (cum laude) from the University of Colorado at Boulder and his MS and PhD in…

  16. Effective Integration of Technology and Instruction. Q&A with Michael Jay. REL Mid-Atlantic Educator Effectiveness Webinar Series

    Science.gov (United States)

    Regional Educational Laboratory Mid-Atlantic, 2015

    2015-01-01

    In this webinar, long-time educator and developer of education technology Michael Jay discussed the importance of using technology to support learning and gave examples of how teachers can integrate technology into their instruction based on the Common Core State Standards and the Next Generation Science Standards. The PowerPoint presentation and…

  17. N-Heterocyclic-Carbene-Catalysed Diastereoselective Vinylogous Mukaiyama/Michael Reaction of 2-(Trimethylsilyloxy)furan and Enones

    KAUST Repository

    Wang, Ying

    2015-10-15

    N-heterocyclic carbenes have been utilised as highly efficient nucleophilic organocatalysts to mediate vinylogous Mukaiyama/Michael reactions of 2-(trimethylsilyloxy)furan with enones to afford γ-substituted butenolides in 44-99% yield with 3:1-32:1 diastereoselectivity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Progress in ultrasonic spray pyrolysis for condensed matter sciences developed from ultrasonic nebulization theories since Michael Faraday

    CSIR Research Space (South Africa)

    Mwakikunga, BW

    2014-01-01

    Full Text Available This review outlines, in great detail, the history of the phenomenon of ultrasonic nebulization of liquids since the discovery of such an effect by Michael Faraday and the explanation of the phenomenon by capillary wave mechanism and “cavitation...

  19. Jack Michael's Appointments at the University of Houston and Arizona State University: Reflections from a Former Student

    Science.gov (United States)

    Mabry, John H.

    2016-01-01

    Jack Michael was an early enthusiast for what is now called applied behavior analysis. His many seminal contributions were through early publications in applied behavior analysis and the work of the students he trained (e.g., T. Ayllon, M. M. Wolf). His close mentorship of students earned him acclaim as a teacher along with his many theoretical…

  20. Solvent-free, catalyst-free aza-Michael addition of cyclohexylamine to diethyl maleate: reaction mechanism and kinetics

    Czech Academy of Sciences Publication Activity Database

    Bláha, Michal; Trhlíková, Olga; Podešva, Jiří; Abbrent, Sabina; Steinhart, Miloš; Dybal, Jiří; Dušková-Smrčková, Miroslava

    2018-01-01

    Roč. 74, č. 1 (2018), s. 58-67 ISSN 0040-4020 Institutional support: RVO:61389013 Keywords : Aza-Michael addition * solvent-free * catalyst-free Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 2.651, year: 2016

  1. Thomas DaCosta Kaufmann and Michael North (eds., Mediating Netherlandish Art and Material Culture in Asia

    Directory of Open Access Journals (Sweden)

    Claartje Rasterhoff

    2015-12-01

    Full Text Available Book notice of: Thomas DaCosta Kaufmann and Michael North (eds., Mediating Netherlandish Art and Material Culture in Asia (Amsterdam Studies in the Dutch Golden Age Amsterdam, Amsterdam University Press, 2014. 348 pp. ISBN 978-90-8964-569-2. € 99,00.

  2. Der Wert von Worten. Michael Serrer aus dem Literaturbüro Düsseldorf im Interview mit der Textpraxis-Redaktion

    Directory of Open Access Journals (Sweden)

    Michael Serrer

    2014-11-01

    Full Text Available Die Textpraxis-Redaktion unterhält sich mit Michael Serrer über Literaturvermittlung in Zeiten der Digitalisierung, über Kanonisierung und die Rolle der Literatur in der Gesellschaft. Michael Serrer ist Leiter des Literaturbüros NRW und Feuilletonist.

  3. Book Review: America’s Blind Spot: Chávez, Oil and US Security by Andrés Cala and Michael Economides

    DEFF Research Database (Denmark)

    Boscan, Luis

    2014-01-01

    Review of: America’s Blind Spot: Chávez, Oil and US Security. Andrés Cala and Michael Economides. Continuum Books. 2012.......Review of: America’s Blind Spot: Chávez, Oil and US Security. Andrés Cala and Michael Economides. Continuum Books. 2012....

  4. 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.

  5. Atomic scale images of acceptors in III-V semiconductors. Band bending, tunneling paths and wave functions

    Energy Technology Data Exchange (ETDEWEB)

    Loth, S.

    2007-10-26

    This thesis reports measurements of single dopant atoms in III-V semiconductors with low temperature Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). It investigates the anisotropic spatial distribution of acceptor induced tunneling processes at the {l_brace}110{r_brace} cleavage planes. Two different tunneling processes are identified: conventional imaging of the squared acceptor wave function and resonant tunneling at the charged acceptor. A thorough analysis of the tip induced space charge layers identifies characteristic bias windows for each tunnel process. The symmetry of the host crystal's band structure determines the spatial distribution of the tunneling paths for both processes. Symmetry reducing effects at the surface are responsible for a pronounced asymmetry of the acceptor contrasts along the principal [001] axis. Uniaxial strain fields due to surface relaxation and spin orbit interaction of the tip induced electric field are discussed on the basis of band structure calculations. High-resolution STS studies of acceptor atoms in an operating p-i-n diode confirm that an electric field indeed changes the acceptor contrasts. In conclusion, the anisotropic contrasts of acceptors are created by the host crystal's band structure and concomitant symmetry reduction effects at the surface. (orig.)

  6. Click and chemically triggered declick reactions through reversible amine and thiol coupling via a conjugate acceptor

    Science.gov (United States)

    Diehl, Katharine L.; Kolesnichenko, Igor V.; Robotham, Scott A.; Bachman, J. Logan; Zhong, Ye; Brodbelt, Jennifer S.; Anslyn, Eric V.

    2016-10-01

    The coupling and decoupling of molecular units is a fundamental undertaking of organic chemistry. Herein we report the use of a very simple conjugate acceptor, derived from Meldrum's acid, for the sequential ‘clicking’ together of an amine and a thiol in aqueous conditions at neutral pH. Subsequently, this linkage can be ‘declicked’ by a chemical trigger to release the original amine and thiol undisturbed. The reactivity differs from that of other crosslinking agents because the selectivity for sequential functionalization derives from an altering of the electrophilicity of the conjugate acceptor on the addition of the amine. We describe the use of the procedure to modify proteins, create multicomponent libraries and synthesize oligomers, all of which can be declicked to their starting components in a controlled fashion when desired. Owing to the mild reaction conditions and ease of use in a variety of applications, the method is predicted to have wide utility.

  7. Substrate dependence of energy level alignment at the donor-acceptor interface in organic photovoltaic devices

    International Nuclear Information System (INIS)

    Zhou, Y.C.; Liu, Z.T.; Tang, J.X.; Lee, C.S.; Lee, S.T.

    2009-01-01

    The interface energy level alignment between copper phthalocyanine (CuPC) and fullerene (C60), the widely studied donor-acceptor pair in organic photovoltaics (OPVs), on indium-tin oxide (ITO) and Mg substrate was investigated. The CuPC/C60 interface formed on ITO shows a nearly common vacuum level, but a dipole and band bending exist, resulting in a 0.8 eV band offset at the same interface on Mg. This observation indicates that the energy difference between the highest occupied molecular orbital of CuPC and the lowest unoccupied molecular orbital of C60, which dictates the open circuit voltage of the CuPC/C60 OPV, can be tuned by the work function of the substrate. Furthermore, the substrate effect on the energy alignment at the donor/acceptor interface can satisfactorily explain that a device with an anode of a smaller work function can provide a higher open circuit voltage.

  8. Giant first hyperpolarizabilities of donor-acceptor substituted graphyne: An ab initio study.

    Science.gov (United States)

    Chakraborti, Himadri

    2016-01-15

    Graphyne (Gy), a theoretically proposed material, has been utilized, for the first time, in a phenomenal donor-Gy-acceptor (D-Gy-A) structure to plan a superior nonlinear optical material. Owing to the extraordinary character of graphyne, this conjugate framework shows strikingly extensive static first hyperpolarizability (β(tot)) up to 128×10(-30) esu which is an enormous improvement than that of the bare graphyne. The donor-acceptor separation plays a key role in the change of β(tot) value. The π-conjugation of graphyne backbone has spread throughout some of the D-A attached molecules and leads to a low band gap state. Finally, two level model clarifies that the molecule having low transition energy should have high first hyperpolarizability. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Positron annihilation in liquids and in solutions containing electron acceptors and charge-transfer complexes

    International Nuclear Information System (INIS)

    Jansen, P.

    1976-05-01

    Positron lifetime measurements and angular correlation measurements were performed in several organic liquids. The results strongly indicate that positronium is contained in a 'bubble' in the liquids. The radius of the bubble can be estimated by using broadness of the narrow component in the angular correlation distribution, and by using the surface tension of the liquids. Both methods give bubble radii from 4-7 A in the solvents investigated. The bubble influences the reaction mechanism between Ps and weak electron acceptors in such a way that the presence of the bubble decreases the reactivity of Ps. Positron lifetime measurements were also performed on a series of mixtures of organic liquids and on electron acceptors and charge-transfer complexes in solution. The results were is agreement with the spur model of Ps formation. (Auth.)

  10. Structural, theoretical and experimental models of photosynthetic antennas, donors and acceptors

    International Nuclear Information System (INIS)

    Barkigia, K.M.; Chantranupong, L.; Fajer, J.; Kehres, L.A.; Smith, K.M.

    1989-01-01

    Theoretical calculations, based on recent x-ray studies of bacterial reaction centers, suggest that the light-absorption properties of the special pair phototraps in bacteria are controlled by the interplanar spacing between the bacteriochlorophyll subunits that constitute the special pairs. The calculations offer attractively simple explanations for the range of absorption spectra exhibited by photosynthetic bacteria. The wide range of (bacterio)chlorophyll skeletal conformations revealed by x-ray diffraction studies raise the intriguing possibility that different conformations, imposed by protein constraints, can modulate the light-absorption and redox properties of the chromophores in vivo. Electron-nuclear double resonance data obtained for the primary acceptors in green plants suggest specific substituent orientations and hydrogen bonding that may help optimize the orientations of the acceptors relative to the donors

  11. Intramolecular Charge-Transfer Interaction of Donor-Acceptor-Donor Arrays Based on Anthracene Bisimide.

    Science.gov (United States)

    Iwanaga, Tetsuo; Ogawa, Marina; Yamauchi, Tomokazu; Toyota, Shinji

    2016-05-20

    We designed anthracene bisimide (ABI) derivatives having two triphenylamine (TPA) groups as donor units at the 9,10-positions to form a novel π-conjugated donor-acceptor system. These compounds and their analogues with ethynylene linkers were synthesized by Suzuki-Miyaura and Sonogashira coupling reactions, respectively. In UV-vis spectra, the linker-free derivatives showed broad absorption bands arising from intramolecular charge-transfer interactions. Introducing ethynylene linkers resulted in a considerable red shift of the absorption bands. In fluorescence spectra, the ethynylene derivatives showed intense emission bands at 600-650 nm. Their photophysical and electrochemical properties were compared with those of the corresponding mono TPA derivatives on the basis of theoretical calculations and cyclic voltammetry to evaluate the intramolecular electronic interactions between the donor and acceptor units.

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

    International Nuclear Information System (INIS)

    Norambuena, Ester; Olea-Azar, Claudio; Delgadillo, Alvaro; Barrera, Mauricio; Loeb, Barbara

    2009-01-01

    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.

  13. 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.

  14. 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.

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

    KAUST Repository

    Alam, Shahidul; Meitzner, Rico; Nwadiaru, Ogechi V.; Friebe, Christian; Cann, Jonathan; Ahner, Johannes; Ulbricht, Christoph; Kan, Zhipeng; Hö ppener, Stephanie; Hager, Martin D.; Egbe, Daniel A. M.; Welch, Gregory C.; Laquai, Fré dé ric; Schubert, Ulrich S.; Hoppe, Harald

    2018-01-01

    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.

  16. Deep and shallow acceptor levels in solid solutions Pb0.98Sm0.02S

    International Nuclear Information System (INIS)

    Hasanov, H.A.; Rahimov, R.Sh.

    2010-01-01

    It is well known that the metal vacancies the energy levels of which take place between permitted energies of valency band, are the main acceptor centers in the led salts and solid solutions on their base. The aim of the given paper is founding of character of acceptor levels in single crystals Pb 0 .98Sm 0 .02S with low concentrations of charge carrier. The deep and shallow acceptor levels are found at investigation of Hall effect in Pb 0 .98Sm 0 .02S solid solution with character of low concentrations of charge carriers in crystals

  17. 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.

  18. 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

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

    International Nuclear Information System (INIS)

    Arora, Vinita; Bakhshi, A.K.

    2010-01-01

    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 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 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 π conjugation.

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

    KAUST Repository

    Woo, Claire H.; Holcombe, Thomas W.; Unruh, David A.; Sellinger, Alan; Fréchet, Jean M. J.

    2010-01-01

    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.

  1. Self-consistent electronic structure of a model stage-1 graphite acceptor intercalate

    International Nuclear Information System (INIS)

    Campagnoli, G.; Tosatti, E.

    1981-04-01

    A simple but self-consistent LCAO scheme is used to study the π-electronic structure of an idealized stage-1 ordered graphite acceptor intercalate, modeled approximately on C 8 AsF 5 . The resulting non-uniform charge population within the carbon plane, band structure, optical and energy loss properties are discussed and compared with available spectroscopic evidence. The calculated total energy is used to estimate migration energy barriers, and the intercalate vibration mode frequency. (author)

  2. The Influence of Solvent Additive on Polymer Solar Cells Employing Fullerene and Non-Fullerene Acceptors

    KAUST Repository

    Song, Xin

    2017-11-27

    Small-molecule-based non-fullerene acceptors (NFAs) are emerging as a new field in organic photovoltaics, due to their structural versatility, the tunability of their energy levels, and their ease of synthesis. High-efficiency polymer donors have been tested with these non-fullerene acceptors in order to further boost the efficiency of organic solar cells. Most of the polymer:fullerene systems are optimized with solvent additives for high efficiency, while little attention has been paid to NFA-based solar cells so far. In this report, the effect of the most common additive, 1,8-diiodooctane (DIO), on PTB7-Th:PC71BM solar cells is investigated and it is compared with non-fullerene acceptor 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno-[1,2-b:5,6b′]di-thiophene (ITIC) devices. It is interesting that the high boiling solvent additive does have a negative impact on the power conversion efficiency when PTB7-Th is blended with ITIC acceptor. The solar cell devices are studied in terms of their optical, photophysical, and morphological properties and find out that PTB7-Th:ITIC devices with DIO results in coarser domains, reduced absorption strength, and slightly lower mobility, while DIO improves the absorption strength of the PTB7-Th:PC71BM blend film and increase the aggregation of PC71BM in the blend, resulting in higher fill factor and Jsc.

  3. The Influence of Solvent Additive on Polymer Solar Cells Employing Fullerene and Non-Fullerene Acceptors

    KAUST Repository

    Song, Xin; Gasparini, Nicola; Baran, Derya

    2017-01-01

    Small-molecule-based non-fullerene acceptors (NFAs) are emerging as a new field in organic photovoltaics, due to their structural versatility, the tunability of their energy levels, and their ease of synthesis. High-efficiency polymer donors have been tested with these non-fullerene acceptors in order to further boost the efficiency of organic solar cells. Most of the polymer:fullerene systems are optimized with solvent additives for high efficiency, while little attention has been paid to NFA-based solar cells so far. In this report, the effect of the most common additive, 1,8-diiodooctane (DIO), on PTB7-Th:PC71BM solar cells is investigated and it is compared with non-fullerene acceptor 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno-[1,2-b:5,6b′]di-thiophene (ITIC) devices. It is interesting that the high boiling solvent additive does have a negative impact on the power conversion efficiency when PTB7-Th is blended with ITIC acceptor. The solar cell devices are studied in terms of their optical, photophysical, and morphological properties and find out that PTB7-Th:ITIC devices with DIO results in coarser domains, reduced absorption strength, and slightly lower mobility, while DIO improves the absorption strength of the PTB7-Th:PC71BM blend film and increase the aggregation of PC71BM in the blend, resulting in higher fill factor and Jsc.

  4. 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.

  5. 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.

  6. Polymer solar cells based on poly(3-hexylthiophene) and fullerene: Pyrene acceptor systems

    Energy Technology Data Exchange (ETDEWEB)

    Cominetti, Alessandra; Pellegrino, Andrea; Longo, Luca [Research Center for Renewable Energies and Environment, Istituto Donegani, Eni S.p.A, Via Fauser 4, IT-28100 Novara (Italy); Po, Riccardo, E-mail: riccardo.po@eni.com [Research Center for Renewable Energies and Environment, Istituto Donegani, Eni S.p.A, Via Fauser 4, IT-28100 Novara (Italy); Tacca, Alessandra; Carbonera, Chiara; Salvalaggio, Mario [Research Center for Renewable Energies and Environment, Istituto Donegani, Eni S.p.A, Via Fauser 4, IT-28100 Novara (Italy); Baldrighi, Michele; Meille, Stefano Valdo [Dipartimento di Chimica, Materiali e Ingegneria Chimica “G. Natta”, Politecnico di Milano, via Mancinelli 7, IT-20131 Milano (Italy)

    2015-06-01

    The replacement of widely used fullerene derivatives, e.g. [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), with unfunctionalized C60 and C70 is an effective approach to reduce the costs of organic photovoltaics. However, solubility issues of these compounds have always represented an obstacle to their use. In this study, bulk-heterojunction solar cells made of poly(3-hexylthiophene) donor polymer, C60 or C70 acceptors and a pyrene derivative (1-pyrenebutiric acid butyl ester) are reported. Butyl 1-pyrenebutirate limits the aggregation of fullerenes and improves the active layer morphology, plausibly due to the formation of pyrene-fullerene complexes which, in the case of pyrene-C70, were also obtained in a crystalline form. Maximum power conversion efficiencies of 1.54% and 2.50% have been obtained using, respectively, C60 or C70 as acceptor. Quantum mechanical modeling provides additional insight into the formation of plausible supermolecular structures via π-π interactions and on the redox behaviour of pyrene-fullerene systems. - Highlights: • Pyrene derivatives favour the dispersion of unfunctionalized fullerenes. • Polymer solar cells with pyrene: C60 adduct as acceptor have efficiencies of 1.54%. • When C60 is substituted with C70 the efficiency is increased to 2.50%. • DFT calculations support the plausibility of the formation of pyrene: fullerene adducts. • The use of unfunctionalized fullerenes may decrease the costs of polymer solar cells.

  7. Amine donor and acceptor influence on the thermodynamics of ω-transaminase reactions

    DEFF Research Database (Denmark)

    Gundersen, Maria T.; Abu, Rohana; Schürmann, Martin

    2015-01-01

    In recent years biocatalytic transamination using ω-transaminase has become established as one of the most interesting routes to synthesize chiral amines with a high enantiomeric purity, especially in the pharmaceutical sector where the demand for such compounds is high. Nevertheless, one limitat...... of such reactions because it may be used to help select suitable donor/acceptor combinations. The results presented here give guidance, with respect to thermodynamics, in order to further extend the application of biocatalytic transamination....... limitation for successful implementation and scale-up is that the thermodynamics of such conversions are frequently found unfavourable. Herein we report experimental measurements of apparent equilibrium constants for several industrially relevant transamination reactions in a systematic manner to better...... understand the effect of amine acceptor and donor choice. For example, we have found that ortho-substitution of acetophenone like molecules, had a significant impact on the thermodynamic equilibrium. Likewise, the effect of cyclic amine acceptors was evaluated and compared to similar non-cyclic structures...

  8. 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.

  9. Surface protection during plasma hydrogenation for acceptor passivation in InP

    International Nuclear Information System (INIS)

    Lopata, J.; Dautremont-Smith, W.C.; Pearton, S.J.; Lee, J.W.; Ha, N.T.; Luftman, H.S.

    1990-01-01

    Various dielectric and metallic films were examined as H-permeable surface protection layers on InP during H 2 or D 2 plasma exposure for passivation of acceptors in the InP. Plasma deposited SiN x , SiO 2 , and a-Si(H) films ranging in thickness from 85 to 225 angstrom were used to protect p-InP during d 2 plasma exposure at 250 degrees C. Optimum protective layer thicknesses were determined by a trade-off between the effectiveness of the layer to prevent P loss from the wafer surface and the ability to diffuse atomic H or D at a rate greater than or equal to that in the underlying InP. SIMS and capacitance-voltage depth profiling were used to determine the extent of D in-diffusion and acceptor passivation respectively. Sputter deposited W and e-beam evaporated Ti films ∼100 Angstrom thick were also evaluated. The W coated sample yielded similar results to those with dielectric films in that acceptors in p-InP were passivated to a similar depth for the same plasma exposure. The 100 Angstrom Ti film, however, did not allow the D to diffuse into the InP substrate. It is surmised that the Ti film trapped the D, thus preventing diffusion into the substrate

  10. Partial purification of xylosyltransferase (XylT) from rat liver and characterization of endogenous acceptors

    International Nuclear Information System (INIS)

    Klinger, M.; Roden, L.

    1986-01-01

    The biosynthesis of the carbohydrate-protein linkage region of most proteoglycan species is initiated by transfer of xylose from UDP-xylose to serine hydroxyl groups in the core protein. The XylT catalyzing this reaction has been previously purified from embryonic chick cartilage and from a rat chondrosarcoma but not from a normal mammalian tissue. In this study, XylT was extracted from rat liver by homogenization in buffer containing 1 M KCl and was partially purified by chromatography on heparin-Sepharose, AH-Sepharose, and on Sepharose-linked tryptic fragments of silk fibroin. The eluate from the latter contained more than 40% of the applied activity and less than 5% of the protein. Gel chromatography of XylT eluted from heparin-Sepharose indicated a mol. wt. of 95,000 to 100,000. Incorporation of ( 3 H)xylose into endogenous acceptors in the crude extract amounted to more than 50% of the total observed with added substrate (silk fibroin). Of the total endogenous acceptor activity in the crude extract, 98% was not adsorbed to heparin-Sepharose and yielded a labeled product which was stable to treatment with 0.5 M NaOH at 20 0 C for 16 h; this material may have been glycogen. In contrast, most of the radioactivity incorporated into the endogenous acceptor in the heparin-Sepharose eluate was alkali-labile, as would be expected for the xylosylated core protein of a proteoglycan

  11. Vacancy clustering and acceptor activation in nitrogen-implanted ZnO

    Science.gov (United States)

    Børseth, Thomas Moe; Tuomisto, Filip; Christensen, Jens S.; Monakhov, Edouard V.; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

    2008-01-01

    The role of vacancy clustering and acceptor activation on resistivity evolution in N ion-implanted n -type hydrothermally grown bulk ZnO has been investigated by positron annihilation spectroscopy, resistivity measurements, and chemical profiling. Room temperature 220keV N implantation using doses in the low 1015cm-2 range induces small and big vacancy clusters containing at least 2 and 3-4 Zn vacancies, respectively. The small clusters are present already in as-implanted samples and remain stable up to 1000°C with no significant effect on the resistivity evolution. In contrast, formation of the big clusters at 600°C is associated with a significant increase in the free electron concentration attributed to gettering of amphoteric Li impurities by these clusters. Further annealing at 800°C results in a dramatic decrease in the free electron concentration correlated with activation of 1016-1017cm-3 acceptors likely to be N and/or Li related. The samples remain n type, however, and further annealing at 1000°C results in passivation of the acceptor states while the big clusters dissociate.

  12. 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.

  13. tRNA acceptor-stem and anticodon bases embed separate features of amino acid chemistry

    Science.gov (United States)

    Carter, Charles W.; Wolfenden, Richard

    2016-01-01

    abstract The universal genetic code is a translation table by which nucleic acid sequences can be interpreted as polypeptides with a wide range of biological functions. That information is used by aminoacyl-tRNA synthetases to translate the code. Moreover, amino acid properties dictate protein folding. We recently reported that digital correlation techniques could identify patterns in tRNA identity elements that govern recognition by synthetases. Our analysis, and the functionality of truncated synthetases that cannot recognize the tRNA anticodon, support the conclusion that the tRNA acceptor stem houses an independent code for the same 20 amino acids that likely functioned earlier in the emergence of genetics. The acceptor-stem code, related to amino acid size, is distinct from a code in the anticodon that is related to amino acid polarity. Details of the acceptor-stem code suggest that it was useful in preserving key properties of stereochemically-encoded peptides that had developed the capacity to interact catalytically with RNA. The quantitative embedding of the chemical properties of amino acids into tRNA bases has implications for the origins of molecular biology. PMID:26595350

  14. Entrevista com Mathieu Dosse, Gian Luigi de Rosa e Michael Kegler

    Directory of Open Access Journals (Sweden)

    Andréia Guerini

    2017-09-01

    Full Text Available O conjunto das três entrevistas que seguem aborda a mesma temática, isto é, aspectos de tradução/adaptação em geral e da tradução do romance Estive em Lisboa e lembrei de você de Luiz Ruffato em particular. O romance de Ruffato foi escrito em 2009, editado em Portugal (Quetzal, 2010 e traduzido para diferentes línguas, como italiano (La Nuova Frontiera, 2011, espanhol (Eterna Cadencia, 2011, francês (Chandeigne, 2015, alemão (Assoziation A, 2016 e, nos próximos meses será publicado em finlandês (Into. O livro foi adaptado para o cinema em 2015, pelo cineasta português José Barahona, sendo exibido em festivais nacionais e internacionais. As entrevistas abaixo foram feitas com os tradutores Gian Luigi De Rosa, Mathieu Dosse e Michael Kegler em 2016. Gian Luigi De Rosa (Itália/1969-- possui doutorado em “Culture e Istituzioni dei paesi di lingue iberiche in età moderna e contemporanea” e é professor de português na Universidade do Salento, em Lecce. É autor de livros e ensaios sobre língua e linguística portuguesa, literatura portuguesa e brasileira e tradução audiovisual e intersemiótica. É também responsável pela elaboração das legendas em italiano do filme Estive em Lisboa e lembrei de você. Mathieu Dosse (Brasil/1978-- é formado pela Université Paris 8, onde estudou Teoria da Tradução. Traduziu para o francês Graciliano Ramos, Luiz Ruffato e João Guimarães Rosa. Michael Kegler (Alemanha/1967-- estudou literatura brasileira e portuguesa na universidade de Frankfurt, sem concluir o curso. Trabalhou como livreiro no Centro do Livro de Língua Portuguesa, antes de se tornar tradutor literário. Traduziu para o alemão José Eduardo Agualusa, Moacyr Scliar, Luiz Ruffato, entre outros autores. Em julho de 2016, junto com Ruffato, recebeu o prêmio literário Hermann Hesse na Alemanha, pela qualidade da obra publicada em conjunto com a sua tradução.

  15. An Oral History Interview with MICHAEL M. CERNEA (interviewer: Judith Freidenberg

    Directory of Open Access Journals (Sweden)

    MICHAEL M. CERNEA

    2008-01-01

    Full Text Available The editors and editorial board of Human Organization are pleased to introduce readers to the following oral history interview with Michael M. Cernea, a development social scientist who has militated throughout his academic career and applied work for "putting people first", in the forefront of development projects and policies. Working for a long time for the promotion of anthropological and sociological knowledge, either in the activities of the World Bank or in the policies and programs of governments of both developed and developing countries, Dr. Cernea cleared pathways for applied social science that are sure to benefit people in development settings for many years to come. Undoubtedly many readers already know Dr. Cernea's work well, especially those of us who teach the anthropology of development or work in applied settings and organizations, but this interview embeds his broad body of work into a personal, human, and at times tragic context that opens with brushes with death, Nazi brutality, and exile. It also provides valuable insights for carrying out the work of development anthropologists within large-scale organizations and governments.This interview with Dr. Cernea was conducted by Dr. Judith Freidenberg, of the University of Maryland, on June 30, 2003, for the Society for Applied Anthropology Oral History Project, headquartered at the University of Kentucky Libraries. This Project aims to create, through the vehicle of oral histories, a record of the life, activities and experiences of number of selected scholars-anthropologists who devoted a great part of their scientific work to research, to applied work in different settings, to inducing development, including to hands-on work on crafting public social policies and actual development programs. The present transcript of the interview was reviewed by both participants for editorial purposes. Michael M. Cernea expanded some of his oral responses, for historical accuracy or to add

  16. Ecossocialismo, romantismo e (autocrítica da modernidade em Michael Löwy

    Directory of Open Access Journals (Sweden)

    Fabio Mascaro Querido

    2008-12-01

    Full Text Available Partindo da concreticidade da crise ecológica e das transformações contemporâneas no âmbito dos processos de acumulação capitalista, o objetivo geral deste artigo é versar algumas notas preliminares a propósito da perspectiva teórica e política do assim chamado ecossocialismo, tal qual formulado em Michael Löwy. “Corrente de pensamento e de ação” cuja resposta à crise ecológica, a um só tempo romântica e socialista, constitui igualmente uma crítica às potencialidades destrutivas contidas no interior do paradigma societário e produtivo da modernidade. Neste trajeto, busca -se uma aproximação à apropriação löwiniana da obra de Walter Benjamin, especialmente de sua crítica do “progresso” moderno e das ideologias apologetas da “modernização”. Almeja -se assim antever a forma através da qual Michael Löwy e os ecossocialistas respondem às profundas transformações da (pós modernidade capitalista contemporânea, com ênfase particular sobre um argumento central projetado na obra do intelectual franco -brasileiro, qual seja: a defesa da necessidade de que o marxismo radicalize “sua crítica da modernidade, do paradigma da civilização ocidental, industrial, moderna, burguesa” (LÖWY, 2000c, p.242, argumento que o levaria, já em meados da década de 1980, a valorizar as potencialidades revolucionárias subjacentes a crítica romântica da modernidade. Por fim, indaga -se sobre a projeção ecossocialista da necessidade de superação revolucionária do paradigma civilizatório propalado pelo capitalismo moderno

  17. Simulation study on the effects of chemical structure and molecular size on the acceptor strength in poly(3-hexylthiophene)-based copolymer with alternating donor and acceptor for photovoltaic applications

    Science.gov (United States)

    Rassamesard, Areefen; Pengpan, Teparksorn

    2017-02-01

    This research assessed the effects of various chemical structures and molecular sizes on the simulated geometric parameters, electron structures, and spectroscopic properties of single-chain complex alternating donor-acceptor (D-A) monomers and copolymers that are intended for use as photoactive layer in a polymer solar cell by using Kohn-Sham density functional theory with B3LYP exchange-correlation functional. The 3-hexylthiophene (3HT) was selected for electron donor, while eight chemicals, namely thiazole (Z), thiadiazole (D), thienopyrazine (TP), thienothiadiazole (TD), benzothiadiazole (BT), thiadiazolothieno-pyrazine (TPD), oxadiazole (OXD) and 5-diphenyl-1,2,4-triazole (TAZ), were employed as electron acceptor functional groups. The torsional angle, bridge bond length, intramolecular charge transfer, energy levels, and molecular orbitals were analyzed. The simulation results reveal that the geometry and electron structure of donor-acceptor monomer and copolymer are significantly impacted by heterocyclic rings, heteroatoms, fused rings, degree of steric hindrance and coplanarity of the acceptor molecular structure. Planar conformation was obtained from the D copolymer, and a pseudo-planar structure with the TD copolymer. The TAZ acceptor exhibited strong steric hindrance due to its bulky structure and non-planarity of its structure. An analysis of the electron structures indicated that the degree of intramolecular electron-withdrawing capability had the rank order TAZ  gaps of TD as well as TPD copolymer indicate that these two copolymers can be used in transparent conducting materials. The copolymer based on BT acceptor exhibited good intramolecular charge transfer and absorbed at 656 nm wavelength which is close to the maximum flux of solar spectrum. Hence, the BT acceptor functional group provides a compromise in the characteristics of a donor-acceptor copolymer, useful in a polymeric candidate material for the photoactive layer in a polymer solar

  18. 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

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

    KAUST Repository

    Alsam, Amani Abdu; Adhikari, Aniruddha; Parida, Manas R.; Aly, Shawkat Mohammede; Bakr, Osman; Mohammed, Omar F.

    2017-01-01

    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

  20. Michael Jackson, Bin Laden and I: functions of positive and negative, public and private flashbulb memories.

    Science.gov (United States)

    Demiray, Burcu; Freund, Alexandra M

    2015-01-01

    This study examined the perceived psychosocial functions of flashbulb memories: It compared positive and negative public flashbulb memories (positive: Bin Laden's death, negative: Michael Jackson's death) with private ones (positive: pregnancy, negative: death of a loved one). A sample of n = 389 young and n = 176 middle-aged adults answered canonical category questions used to identify flashbulb memories and rated the personal significance, the psychological temporal distance, and the functions of each memory (i.e., self-continuity, social-boding, directive functions). Hierarchical regressions showed that, in general, private memories were rated more functional than public memories. Positive and negative private memories were comparable in self-continuity and directionality, but the positive private memory more strongly served social functions. In line with the positivity bias in autobiographical memory, positive flashbulb memories felt psychologically closer than negative ones. Finally, middle-aged adults rated their memories as less functional regarding self-continuity and social-bonding than young adults. Results are discussed regarding the tripartite model of autobiographical memory functions.

  1. Novel Interecting Blends Based on Amino Terminited Oligoimides by Using Michael Addition Reaction-II

    Directory of Open Access Journals (Sweden)

    Rita R. Patel

    2012-01-01

    Full Text Available New amino terminated oligoimides (AOIs were prepared by the Michael addition reaction of various bismaleimide (1, namely, 1-(4-((4-((2, 5-dioxocyclopent-3 enylamino methyl cyclohexyl methyl cyclohexyl-1, 6-dihydropyridine-2, 5-dione with excess of various diamines (2a-c. These AOIs were characterized by elemental analysis, FT-IR spectral studies and number average molecular weight estimated by non-aqueous conductometric titrations. AOIs were then treated with acrylol chloride and resultant acryl terminated oligoimides (AcOIs samples were also characterized thermogravimetrically. Each of these AcOI was then combined with the N-phenyl maleimide (PM in THF solvent. The resultant suspensions were then heated in the presence of azobisisobutyronitrile (AIBN as an initiator. The AcOI and PM polymerized through double bond simultaneously and form interacting blends, which were analyzed thermogravimetrically. The glass fiber reinforced composites were fabricated by using the suspensions of the AcOI and PM. The composites of Interacting blends were analyzed for their mechanical, chemical and electrical properties.

  2. Nacionalismos e internacionalismo: um debate entre Michael Löwy e Michel Cahen

    Directory of Open Access Journals (Sweden)

    Ângela Lazagna

    2008-11-01

    Full Text Available Este artigo consiste em um debate realizado entre Michel Löwy e Michael Cahen em meados dos anos 1990 e revisto para esta publicação. Mesmo que a discussão refira-se a acontecimentos que até certo ponto podem ser considerados datados, a preocupação de fundo que é comum a esses artigos concede-lhes atualidade: a necessidade do aprofundamento de uma reflexão, a partir da teoria marxista, sobre o problema dos nacionalismos e do internacionalismo em tempos de mundialização. Esse aprofundamento, segundo os autores, faz-se necessário sobretudo por meio de uma reflexão que rompa criticamente com uma visão eurocêntrica dos diferentes nacionalismos e que supere a atitude de muitos marxistas de desprezarem tudo aquilo que não seja diretamente relevante à "consciência de classe".

  3. A man and his island: The island mirror in Michael Crummey’s Sweetland

    Directory of Open Access Journals (Sweden)

    Laurie Brinklow

    2016-05-01

    Full Text Available Between 1946 and 1975, dozens of islands and outports in the Canadian province of Newfoundland and Labrador were abandoned as part of a government resettlement policy. Families and communities were torn apart, and a culture and way of life that revolved around the fishery changed irrevocably. The practice, which continues to this day, has been well documented, particularly by artists and writers. Michael Crummey’s 2014 novel Sweetland is a recent iteration. The relationship between humans and place is complex: on an island, with compressed space and a very real boundary that is the ocean, emotional attachments to one’s place are often heightened and distilled. What happens when a person is displaced from his or her island; when bonds of attachment are severed and one’s mirrored double is destroyed? Sweetland offers a fictional lens through which we see an example of a mirrored relationship between an island protagonist and his island setting. Exploring themes of attachment to place, and what Barry Lopez calls a “storied” or “reciprocal” relationship with the land, this paper examines what happens to a man when confronted with leaving an island he knows as deeply as his own body and soul; and how the island reacts.

  4. Selective bird predation on the peppered moth: the last experiment of Michael Majerus.

    Science.gov (United States)

    Cook, L M; Grant, B S; Saccheri, I J; Mallet, J

    2012-08-23

    Colour variation in the peppered moth Biston betularia was long accepted to be under strong natural selection. Melanics were believed to be fitter than pale morphs because of lower predation at daytime resting sites on dark, sooty bark. Melanics became common during the industrial revolution, but since 1970 there has been a rapid reversal, assumed to have been caused by predators selecting against melanics resting on today's less sooty bark. Recently, these classical explanations of melanism were attacked, and there has been general scepticism about birds as selective agents. Experiments and observations were accordingly carried out by Michael Majerus to address perceived weaknesses of earlier work. Unfortunately, he did not live to publish the results, which are analysed and presented here by the authors. Majerus released 4864 moths in his six-year experiment, the largest ever attempted for any similar study. There was strong differential bird predation against melanic peppered moths. Daily selection against melanics (s ≈ 0.1) was sufficient in magnitude and direction to explain the recent rapid decline of melanism in post-industrial Britain. These data provide the most direct evidence yet to implicate camouflage and bird predation as the overriding explanation for the rise and fall of melanism in moths.

  5. Creative Industries, Value Theory and Michael Heinrich’s New Reading of Marx

    Directory of Open Access Journals (Sweden)

    Frederick H. Pitts

    2015-06-01

    Full Text Available This article utilises the new reading of Marx found in the work of Michael Heinrich to analyse the creative industries. It considers the role played in the production of value by the labour that takes place in the sphere of circulation. The specific focus is on creative industries such as graphic design, advertising and branding. It applies Heinrich's conceptualisation of 'social validation' to these sectors. This suggests that valorisation depends upon goods and services attaining commodity status by selling for money. Value is subject to this validation. The capitalist use of advertising, graphic design and branding guarantees the possibility of this validation. Using Heinrich, it reevaluates claims made about the creative industries and cognate fields in three main respects. First, it exposes as inadequate certain Marxist understandings of productive and unproductive labour and the place of circulation activities within this distinction. Second, it refutes autonomist Marxist claims as to the immeasurability of immaterial labour and the redundancy of the law of value. Third, it suggests that creative industries possess a significant role in a capitalist economy blighted by a necessity towards the overproduction of commodities.

  6. Diffusible gradients are out - an interview with Lewis Wolpert. Interviewed by Richardson, Michael K.

    Science.gov (United States)

    Wolpert, Lewis

    2009-01-01

    In 1969, Lewis Wolpert published a paper outlining his new concepts of "pattern formation" and "positional information". He had already published research on the mechanics of cell membranes in amoebae, and a series of classic studies of sea urchin gastrulation with Trygve Gustavson. Wolpert had presented his 1969 paper a year earlier at a Woods Hole conference, where it received a very hostile reception: "I wasnt asked back to America for many years!". But with Francis Crick lining up in support of diffusible morphogen gradients, positional information eventually became established as a guiding principle for research into biological pattern formation. It is now clear that pattern formation is much more complex than could possibly have been imagined in 1969. But Wolpert still believes in positional information, and regards intercalation during regeneration as its best supporting evidence. However, he and others doubt that diffusible morphogen gradients are a plausible mechanism: "Diffusible gradients are too messy", he says. Since his retirement, Lewis Wolpert has remained active as a theoretical biologist and continues to publish in leading journals. He has also campaigned for a greater public understanding of the stigma of depression. He was interviewed at home in London on July 26th, 2007 by Michael Richardson.

  7. Regression and new beginnings: Michael, Alice and Enid Balint and the circulation of ideas.

    Science.gov (United States)

    Sklar, Jonathan

    2012-08-01

    This article offers a new evaluation of Michael Balint's history. It starts with his growing up in Hungary and examines the central concepts of his writing: the analytic pair, regression and the basic fault and creativity, up to and including his renowned work on the eponymous Balint groups (which forged a unique link between psychoanalysis and medicine). While his name is, of course, well known, this article aims to bring his ideas to the attention of a modern analytic audience. Having trained in the 1920s with Ferenczi, Balint brought Ferenczi's literary inheritance to England where he lived until his death in 1970. His connections to Klein, Winnicott and Lacan, all of whom respected his analytic stance, are also examined. Furthermore, this article argues that his ideas were filtered through the theoretical lens of his first wife Alice Balint and later through Enid Balint, both of whom played a key - and rarely recognised - role in the development of his thought. It ends with a brief discussion of his ideas on analytic training and his quest, successful only after his death, to publish the complete Freud-Ferenczi correspondence, together with Ferenczi's diary. Copyright © 2012 Institute of Psychoanalysis.

  8. Losing Touch: A Theology of Death for Michael Haneke’s Amour

    Directory of Open Access Journals (Sweden)

    Taylor Worley

    2016-11-01

    Full Text Available This proposed theology of death for Michael Haneke’s Amour, a fraught but poignant piece of cinema, will employ Martin Heidegger’s existentialism to reframe the ethical structure of the film and apply a “lived theology” rejoinder to its perceived hopelessness. The proposal will address the question of ethics in relation to Haneke’s cinema, in particular his seemingly nihilistic perspective and confrontational style. To do so, it will revisit the film itself and examine the ways that Georges and Anne’s love is tested. Principally, we examine the film’s great question, which—in the filmmaker’s own words—is: “How do I cope with the suffering of a loved one?” With aid from the theologian Dietrich Bonhoeffer, this ‘lived theology’ proposal will attempt to give an account of love’s irrepressible strength in the midst of even astounding suffering. While Heidegger’s ethic of resoluteness calls for interiority and solitude, Bonhoeffer’s account of death more satisfactorily invokes a transcendent summons contained within our own pledges to loved ones. Such a theological reading of Haneke’s Amour will draw two distinct conclusions: first, the film exposes the superficiality of any hoped-for solitude or escape from a loved one’s death, and secondly, it demonstrates that the mutuality of authentic love entails impossible sacrifices.

  9. La figura del libro in Die unendliche Geschichte di Michael Ende: da finestra a varco

    Directory of Open Access Journals (Sweden)

    Elena Di Cesare

    2015-01-01

    Full Text Available The book is an object which can be considered as a window in the novel Die unendliche Geschichte (1979 written by Michael Ende. It allows Bastian to look at the world of Phantasien and to communicate indirectly with the Childlike Empress. Furthermore, this object will show its function as an symbol of evolution, which will enable the passage of the protagonist into the world of Phantasien: first the book appears as a window, then it becomes a two-way-mirror that allows Bastian and Atreju to look at each other, and finally it turns into a gate which enables them to live many adventures together. Die unendliche Geschichte can be considered as a modern Bildungsroman in which the young protagonist gradually reaches his maturation. This progress must be seen in a psychological perspective: it is the growth of a child-mind through literature which makes reference to the German novel tradition but also (as children’s literature to the world of unconsciousness.

  10. Synthesis of some pyridine and pyrimidine derivatives via Michael-Addition

    International Nuclear Information System (INIS)

    El-Baih, Fatma E.M.; Al-Rasheed, Hessa H.; Al-Hazimi, Hassan M.

    2006-01-01

    Synthesis of pyridine and pyrimidine analogues 4 and 6-9 were achieved by Michael-addition of compounds containing either active methylene groups like, malononitrile , ethyl cyanoacetate and 1-tetralone or compounds containing active hydrogen atoms like, guanidine in the presence of an oxidizing agent and thiourea to 2-arylmethylidine-1-tetralone and 2-arylmethylidine-6-methoxy-1-tetralone (2) (enones). Addition of malononitrile in piperidine at room temperature to 2-amino-3-cyno-naphtho [1, 2-malonoitrile in sodium alkoxide or sodium hydroxide to 2 gave 4. Cyclization of 3a with acetic anhydride in the presence of conc. H2sO4 gave the naphtha-pyrano[2, 3-d]pyrimidin-8-one (5). Condensation of the pyrimidine thione derivatives 9 with chloroacetic acid gave the 3-oxobenzo[h]thiazoladino[2, 3-b]quinazoline derivatives (10), which were reacted through their active methylene groups with aromatic aldehydes to give the arylidine derivatives 11. These compounds were also prepared in one step by reacting 9 with chloroacetic acid and aromatic aldehydes. Condensation of 9 with 3-bromopropanoic acid gave 4-oxo-benzo[h]1, 3-thiazino[2, 3-b]quinazoline derivatives (12). The structures of the prepared compounds were mainly confirmed on the basis of spectroscopic methods. (author)

  11. Template Dimerization Promotes an Acceptor Invasion-Induced Transfer Mechanism during Human Immunodeficiency Virus Type 1 Minus-Strand Synthesis

    OpenAIRE

    Balakrishnan, Mini; Roques, Bernard P.; Fay, Philip J.; Bambara, Robert A.

    2003-01-01

    The biochemical mechanism of template switching by human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and the role of template dimerization were examined. Homologous donor-acceptor template pairs derived from the HIV-1 untranslated leader region and containing the wild-type and mutant dimerization initiation sequences (DIS) were used to examine the efficiency and distribution of transfers. Inhibiting donor-acceptor interaction was sufficient to reduce transfers in DIS-containin...

  12. Enantiopure vs. Racemic Naphthalimide End-Capped Helicenic Non-Fullerene Electron Acceptors: Impact on Organic Photovoltaics Performance

    OpenAIRE

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

    2017-01-01

    International audience; 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 jumpi...

  13. 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.

  14. Acceptor thickness effect of exciplex and electroplex emission at heterojunction interface in organic light-emitting diodes

    Science.gov (United States)

    Zhang, Wei; Yu, Junsheng; Yuan, Kai; Jiang, Yadong; Zhang, Qing; Cao, Kangli

    2010-10-01

    Organic light-emitting diodes (OLEDs) consisted of a novel fluorene derivative of 5,6-bis(9,9-dihexyl-9H-fluoren-2-yl)- 2,3-diisocyano-2,3-dihydropyrazine (BDHFLCNPy) and a hole transporting material of N,N'-Di-[(1-naphthalenyl)- N,N'-diphenyl](1,1'-biphenyl)-4,4'-diamine (NPB) were fabricated, and electroluminescence (EL) spectrum of devices were investigated. It was found that light emission around 650 nm observed in devices came from exciplex generated at heterojunction interface by NPB molecules worked as electron donor and BDHFLCNPy molecules worked as electron acceptor. Moreover, a shoulder peak around 500 nm ascribed to BDHFLCNPy exciton was observed. To systemically study the effect of heterojunction structure in exciplex formation, OLEDs with different thickness of acceptor were fabricated. The results illustrated that a shoulder peak around 600 nm occurred in EL when acceptor thickness increases, and BDHFLCNPy exciton emitting strength is relatively altered. The emission band around 600 nm is due to electroplex. The L-V-J properties of OLEDs show that device with the thinnest acceptor layer has the highest luminance and current density. On the contrary, OLEDs with thicker acceptor layer have higher luminance efficiency. The different recombination mechanism of exciton, exciplex and electroplex in heterojunction were studied. Furthermore, the acceptor thickness effect of exciplex and electroplex generating mechanism and energy transferring mechanism between them was also discussed.

  15. “This fabulous flotsam”: Michael Moorcock’s Urban Anthropology in “London under London”

    Directory of Open Access Journals (Sweden)

    Houswitschka Christoph

    2015-07-01

    Full Text Available Michael Moorcock is often described as “one of the most prolific and varied writers working in Britain” (Malcolm 146. His success as a writer and editor of science fiction and fantasy literature is well established, but he is also the author of two novels about London, Mother London (1988 and King of the City (2000. Hardly known, Mother London by Michael Moorcock, offers itself to a variety of approaches that have been widely discussed in the context of studies on English literature during the Thatcher years, post-modernism, and psycho-geography. The novel resonates with the author’s own childhood in war-time London without being autobiographical. It tells the story of three Londoners who were traumatised during the Blitz. The following article focuses on the mysteries of subterranean London that represents the hidden and unconscious identities of its inhabitants in the post-war period.

  16. Theoretical study on the reaction mechanisms of Michael chirality addition between propionaldehyde and nitroalkene catalyzed by an enantioselective catalyst.

    Science.gov (United States)

    Zhou, Xinming; Li, Ling; Sun, Xuejun; Wang, Yajun; Du, Dongmei; Fu, Hui

    2018-06-01

    The asymmetric Michael addition between propionaldehyde and nitroalkene catalyzed by 8-(ethoxycarbonyl)-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid has obtained relatively high yields and excellent enantioselectivities at room temperature. In this study, the molecular structures and optical activity of the most stable conformation I are optimized at B3LYP/6-311++ G(d,p) level. We find that levorotatory conformation I catalyzing the same Michael addition can produce laevo-product A and dextrorotatory conformation I' can obtain the dextral-product A'. These results have guiding significance for further studying on the new chemzymes and the mechanism of the obtained different chiral products. © 2018 Wiley Periodicals, Inc.

  17. O que é a Multidão? Questões para Michael Hardt e Antonio Negri

    Directory of Open Access Journals (Sweden)

    Nicholas Brown

    2006-07-01

    Full Text Available Multidão, livro mais recente de Michael Hardt e Antonio Negri, é uma tentativa de nomear e compreender as condições que envolvem a dinâmica social do século xxi. Na entrevista a seguir, Hardt e Negri discorrem sobre as possibilidades de constituição da multidão como agente político, discutem os fundamentos do livro e defendem conceitos que consideram determinantes para a compreensão dos novos tempos, tais como biopolítica e biopoder.Multitude, Michael Hardt and Antonio Negri’s latest book, is an attempt at understanding conditions involving social dynamics in the xxi century. In the interview below, Hardt and Negri consider the constitution of the multitude as a political agent, discuss the structure of their book and support concepts seen as crucial for the comprehension of our time, such as biopolitics and biopower.

  18. The works of Joseph and Michael Haydn in Ondřej Horník's collection

    Czech Academy of Sciences Publication Activity Database

    Freemanová, Michaela

    2017-01-01

    Roč. 9, 1-2 (2017), s. 14-23 ISSN 1803-7828 Institutional support: RVO:68378076 Keywords : music manuscripts * Joseph Haydn * Michael Haydn * Ondřej Horník's collection * church music Subject RIV: AL - Art, Architecture, Cultural Heritage OBOR OECD: Performing arts studies ( Music ology, Theater science, Dramaturgy) http://www.nm.cz/publikace/archiv.php?id=16

  19. Leadership and creativity in public services: An interview with Lord Michael Bichard, Chair of the National Audit Office

    OpenAIRE

    Bolden, R.; O'Regan, N.

    2018-01-01

    This interview with Lord Michael Bichard, one of the most distinguished public sector leaders in the UK, explores his ideas around the relationship between leadership, creativity and innovation. A champion of place-based approaches to public services, where citizens are actively involved in service design, delivery and appraisal, Bichard advocates the need for inclusive and supportive leadership that enables the emergence of the kinds of creativity required to respond to the financial challen...

  20. Catalytic Enantioselective Synthesis of 3,4-Unsubstituted Thiochromenes through Sulfa-Michael/Julia-Kocienski Olefination Cascade Reaction.

    Science.gov (United States)

    Simlandy, Amit Kumar; Mukherjee, Santanu

    2017-05-05

    A highly enantioselective cascade sulfa-Michael/Julia-Kocienski olefination reaction between 2-mercaptobenzaldehydes and β-substituted vinyl PT-sulfones has been realized for the synthesis of 3,4-unsubstituted 2H-thiochromenes. This reaction, catalyzed by diphenylprolinol TMS ether, proceeds through an aromatic iminium intermediate and furnishes a wide range of 2-substiuted 2H-thiochromenes with excellent enantioselectivities (up to 99:1 er).

  1. Solid State Ionics: from Michael Faraday to green energy-the European dimension.

    Science.gov (United States)

    Funke, Klaus

    2013-08-01

    Solid State Ionics has its roots essentially in Europe. First foundations were laid by Michael Faraday who discovered the solid electrolytes Ag 2 S and PbF 2 and coined terms such as cation and anion , electrode and electrolyte . In the 19th and early 20th centuries, the main lines of development toward Solid State Ionics, pursued in Europe, concerned the linear laws of transport, structural analysis, disorder and entropy and the electrochemical storage and conversion of energy. Fundamental contributions were then made by Walther Nernst, who derived the Nernst equation and detected ionic conduction in heterovalently doped zirconia, which he utilized in his Nernst lamp. Another big step forward was the discovery of the extraordinary properties of alpha silver iodide in 1914. In the late 1920s and early 1930s, the concept of point defects was established by Yakov Il'ich Frenkel, Walter Schottky and Carl Wagner, including the development of point-defect thermodynamics by Schottky and Wagner. In terms of point defects, ionic (and electronic) transport in ionic crystals became easy to visualize. In an 'evolving scheme of materials science', point disorder precedes structural disorder, as displayed by the AgI-type solid electrolytes (and other ionic crystals), by ion-conducting glasses, polymer electrolytes and nano-composites. During the last few decades, much progress has been made in finding and investigating novel solid electrolytes and in using them for the preservation of our environment, in particular in advanced solid state battery systems, fuel cells and sensors. Since 1972, international conferences have been held in the field of Solid State Ionics, and the International Society for Solid State Ionics was founded at one of them, held at Garmisch-Partenkirchen, Germany, in 1987.

  2. Solid State Ionics: from Michael Faraday to green energy—the European dimension

    Science.gov (United States)

    Funke, Klaus

    2013-01-01

    Solid State Ionics has its roots essentially in Europe. First foundations were laid by Michael Faraday who discovered the solid electrolytes Ag2S and PbF2 and coined terms such as cation and anion, electrode and electrolyte. In the 19th and early 20th centuries, the main lines of development toward Solid State Ionics, pursued in Europe, concerned the linear laws of transport, structural analysis, disorder and entropy and the electrochemical storage and conversion of energy. Fundamental contributions were then made by Walther Nernst, who derived the Nernst equation and detected ionic conduction in heterovalently doped zirconia, which he utilized in his Nernst lamp. Another big step forward was the discovery of the extraordinary properties of alpha silver iodide in 1914. In the late 1920s and early 1930s, the concept of point defects was established by Yakov Il'ich Frenkel, Walter Schottky and Carl Wagner, including the development of point-defect thermodynamics by Schottky and Wagner. In terms of point defects, ionic (and electronic) transport in ionic crystals became easy to visualize. In an ‘evolving scheme of materials science’, point disorder precedes structural disorder, as displayed by the AgI-type solid electrolytes (and other ionic crystals), by ion-conducting glasses, polymer electrolytes and nano-composites. During the last few decades, much progress has been made in finding and investigating novel solid electrolytes and in using them for the preservation of our environment, in particular in advanced solid state battery systems, fuel cells and sensors. Since 1972, international conferences have been held in the field of Solid State Ionics, and the International Society for Solid State Ionics was founded at one of them, held at Garmisch-Partenkirchen, Germany, in 1987. PMID:27877585

  3. Corrupting Capitalism: Michael Ende’s Momo and “Cathedral Station”

    Directory of Open Access Journals (Sweden)

    Heike Polster

    2016-01-01

    Full Text Available Michael Ende, the well-known author of The Neverending Story , foresaw dramatic changes in the fabric of society resulting from a turn toward neoliberal policies. One such far-reaching and dangerous change has to do with a diminishing of temporal autonomy, the ability to freely determine the use and meaning of our time. This article explores how neoliberalism is shaping our concept of time and our experience of it. In an effort to demonstrate the process and the line of reasoning behind the monetization of time, and to connect time to more qualitative considerations of the human condition, I shall demonstrate how Ende conceptualizes time as an integral part of the accumulation process of capitalism. I also discuss a fairly cryptic short story, “Cathedral Station,” that envisions “the mystery of money.” Utilizing Walter Benjamin’s critique issued in his 1921 fragment “Capitalism as Religion,” I outline Ende’s dystopian vision of the uncontested, unquestioned reign of capitalism as a religious cult. Read together, the novel and the short story offer a way of contrasting two extreme byproducts of capitalism’s colonization of time, namely what I would call an “ideology of work” and an “ideology of growth.” The first of these is a result of capitalism’s commodification of time according to liberal ideals such as choice, freedom, and self-interest. The second is a decidedly neoliberal phenomenon in that the “financialization of everything,” to use David Harvey’s phrase, results in the ever-present expectation of unlimited, exponential growth. By drawing out these two interconnected ideologies through close readings, the subtle processes of capitalism’s colonization of time are revealed.

  4. Solid State Ionics: from Michael Faraday to green energy—the European dimension

    Directory of Open Access Journals (Sweden)

    Klaus Funke

    2013-01-01

    Full Text Available Solid State Ionics has its roots essentially in Europe. First foundations were laid by Michael Faraday who discovered the solid electrolytes Ag2S and PbF2 and coined terms such as cation and anion, electrode and electrolyte. In the 19th and early 20th centuries, the main lines of development toward Solid State Ionics, pursued in Europe, concerned the linear laws of transport, structural analysis, disorder and entropy and the electrochemical storage and conversion of energy. Fundamental contributions were then made by Walther Nernst, who derived the Nernst equation and detected ionic conduction in heterovalently doped zirconia, which he utilized in his Nernst lamp. Another big step forward was the discovery of the extraordinary properties of alpha silver iodide in 1914. In the late 1920s and early 1930s, the concept of point defects was established by Yakov Il'ich Frenkel, Walter Schottky and Carl Wagner, including the development of point-defect thermodynamics by Schottky and Wagner. In terms of point defects, ionic (and electronic transport in ionic crystals became easy to visualize. In an 'evolving scheme of materials science', point disorder precedes structural disorder, as displayed by the AgI-type solid electrolytes (and other ionic crystals, by ion-conducting glasses, polymer electrolytes and nano-composites. During the last few decades, much progress has been made in finding and investigating novel solid electrolytes and in using them for the preservation of our environment, in particular in advanced solid state battery systems, fuel cells and sensors. Since 1972, international conferences have been held in the field of Solid State Ionics, and the International Society for Solid State Ionics was founded at one of them, held at Garmisch-Partenkirchen, Germany, in 1987.

  5. Suspense, culpa y cintas de vídeo. Caché/Escondido de Michael Haneke

    Directory of Open Access Journals (Sweden)

    Miguel Martínez-Cabeza

    2011-12-01

    Full Text Available Caché/Escondido (2005 representa dentro de la filmografía de Michael Haneke el ejemplo más destacado de síntesis de los planteamientos formales e ideológicos del cineasta austriaco. Este artículo analiza el filme como manifiesto cinematográfico y como explotación de las convenciones genéricas para construir un modelo de espectador reflexivo. La investigación del modo en que el director plantea y abandona las técnicas del suspense aporta claves para explicar el éxito casi unánime de crítica y la respuesta mucho menos homogénea de las audiencias. El desencadenante de la trama, unas cintas de vídeo que reciben los Laurent, es alusión directa a Carretera Perdida (1997 de David Lynch; no obstante, el misterio acerca del autor de la videovigilancia pierde interés en relación al sentimiento de culpa que desencadena en el protagonista. El episodio infantil de celos y venganza hacia un niño argelino y la actitud del Georges adulto representan una alegoría de la relación de Francia con su pasado colonial que tampoco cierra la narración de Haneke. Es precisamente la apertura formal con que el filme (desestructura cuestiones actuales como el límite entre la responsabilidad individual y colectiva lo que conforma un espectador tan distanciado de la diégesis como consciente de su propio papel de observador.

  6. 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.

  7. Making highly conductive ZnO: creating donors and destroying acceptors

    Science.gov (United States)

    Look, D. C.; Leedy, K. D.

    2012-02-01

    We obtain room-temperature resistivities as low as ρ =1.4 x 10-4 Ω-cm in transparent Ga-doped ZnO grown on Al2O3 by pulsed laser deposition (PLD) at 200 °C in 10 mTorr of pure Ar and then annealed in a Zn enfivironment. Donor ND and acceptor NA concentrations are calculated from a recently developed scattering theory that is valid for any degenerate semiconductor material and requires only two input parameters, mobility μ and carrier concentration n measured at any temperature in the range 5 - 300 K. By comparison with SIMS and positron annihilation measurements, it has been shown that the donors in these samples are mostly GaZn, as expected, but that the acceptors are point defects, Zn vacancies VZn. PLD growth in Ar at 200 °C produces a high concentration of donors [GaZn] = 1.4 x 1021 cm-3, but VZn acceptors are produced at the same time, due to self-compensation. Fortunately, a large fraction of the VZn can be eliminated by annealing in a Zn environment. The theory gives ND and NA, and thus [GaZn] and [VZn], at each step of the growth and annealing process. For convenience, the theory is presented graphically, as plots of μ vs n at various values of compensation ratio K = NA/ND. From the value of K corresponding to the experimental values of μ and n, it is possible to calculate ND = n/(1 - K) and NA = nK/(1 - K).

  8. 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

  9. 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.

  10. Donor-π-Acceptor Polymer with Alternating Triarylborane and Triphenylamine Moieties.

    Science.gov (United States)

    Li, Haiyan; Jäkle, Frieder

    2010-05-12

    A luminescent main chain donor-π-acceptor-type polymer (4) was prepared via organometallic polycondensation reaction followed by post modification. With both electron-rich amine and electron-deficient borane moieties embedded in the main chain, 4 exhibits an interesting ambipolar character: it can be reduced and oxidized electrochemically at moderate potentials and shows a strong solvatochromic effect in the emission spectra. Complexation studies show that 4 selectively binds to fluoride and cyanide; quantitative titration with cyanide reveals a two-step binding process. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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

  12. 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.

  13. Polythiophenes and fullerene derivatives based donor-acceptor system: topography by atomic force microscopy

    International Nuclear Information System (INIS)

    Marcakova, M. L.; Repovsky, D.; Cik, G.; Velic, D.

    2017-01-01

    The goal of this work is to examine the surface of a polythiophene/fullerene film in order to understand the structure. In this work polythiophene is used as electron donor and fullerene-derivative is used as electron acceptor. Atomic force microscopy (AFM), is an ideal method to study surfaces and nanostructures. Surfaces of fullerene C60 , fullerene-derivates PCBM, polythiophene P12 and a mixture of P12 and PCBM are characterized. In all samples, the average roughness, the arithmetical value of divergence from the high of the surface, is determined concluding that P12 and PCBM mix together well and form a film with specific topography. (authors)

  14. Research of acceptor impurity thermal activation in GaN: Mg epitaxial layers

    Directory of Open Access Journals (Sweden)

    Aleksandr V. Mazalov

    2016-06-01

    The effect of thermal annealing of GaN:Mg layers on acceptor impurity activation has been investigated. Hole concentration increased and mobility decreased with an increase in thermal annealing temperature. The sample annealed at 1000 °C demonstrated the lowest value of resistivity. Rapid thermal annealing (annealing with high heating speed considerably improved the efficiency of Mg activation in the GaN layers. The optimum time of annealing at 1000 °C has been determined. The hole concentration increased by up to 4 times compared to specimens after conventional annealing.

  15. Donor and Acceptor Polymers for Bulk Hetero Junction Solar Cell and Photodetector Applications

    KAUST Repository

    Cruciani, Federico

    2018-04-01

    Bulk heterojunction (BHJ) devices represent a very versatile family of organic cells for both the fields of solar energy conversion and photodetection. Organic photovoltaics (OPV) are an attractive alternative to their silicon-based counterparts because of their potential for low-cost roll-to-roll printing, and their intended application in light-weight mechanically conformable devices and in window-type semi-transparent PV modules. Of all proposed OPV candidates, polymer donor with different absorption range are especially promising when used in conjunction with complementary absorbing acceptor materials, like fullerene derivatives (PCBM), conjugated molecules or polymers, achieving nowadays power conversion efficiencies (PCEs) in the range of 10-13% and being a step closer to practical applications. Among the photodetectors (PD), low band gap polymer blended with PCBM decked out the attention, given their extraordinary range of detection from UV to IR and high detectivity values reached so far, compared to the inorganic devices. Since the research has been focused on the enhancement of those numbers for an effective commercialization of organic cells, the topic of the following thesis has been centered on the synthesis of different polymer structures with diverse absorption ranges, used as donor or acceptor, with emphasis on performance in various BHJ devices either for solar cells and photodetectors. In the first part, two new wide band gap polymers, used as donor material in BHJ devices blended with fullerene and small molecule acceptors, are presented. The PBDT_2FT and PBDTT_2FT have shown nice efficiencies from 7% to 9.8%. The device results are implemented with a morphology study and a specific application in a semi-transparent tandem device, reaching a record PCE of 5.4% for average level of transparency of 48%. In another section two new low band gap polymers (Eopt~ 1.26 eV) named DTP_2FBT and (Eopt~ 1.1 eV) named BDTT_BTQ are presented. While the DTP

  16. The Relative Hydrogen Bonding Strength of Oxygen and Nitrogen Atoms as a Proton Acceptor

    International Nuclear Information System (INIS)

    Hyun, Jong Cheol; Lee, Ho Jin; Kim, Nak Kyoon; Choi, Young Sang; Park, Jeung Hee; Yoon, Chang Ju

    1999-01-01

    The thermodynamic parameters for the formation of the hydrogen bonding were widely used to understand the protein- ligand interaction. We have been interested in the hydrogen bonding strength of various proton acceptors toward the amide in a nonpolar solvent, This work is in the line of our interest. In drug design, the functional group is often replaced in order to enhance or reduce the binding affinity, which is usually determined by hydrogen bonding strength. Therefore, to understand this biochemical process the knowledge of relative hydrogen bonding strength is of importance.

  17. Influence of electron acceptor on lyoluminescence of irradiated lithium and sodium fluoride

    International Nuclear Information System (INIS)

    Ehrts, D.P.; Dzelme, Yu.R.; Malin'sh, A.A.; Gasyavichus, I.G.; Tiliks, Yu.E.

    1989-01-01

    The influence of nitrate ions and the dissolution rate upon the stationary and non-stationary lyoluminescence has been studied for gamma-irradiated at 45 deg C and dose 10 4 Gy/h lithium and sodium fluorides when dissolving in a concentrated sulfuric acid under variuos disslution conditions. The lyoluminescence of both types is shown to depend on the acceptor concentration in the solvent and the dependence change is determined by reactions between chemically active defects at various depths of the crystal's surface layer affected by the solvent and the dissolution rate. The former reactions depend on the radiation defects' distibution in the crystal volume

  18. Synthesis and spectroscopic characterization of a fluorescent pyrrole derivative containing electron acceptor and donor groups

    Science.gov (United States)

    Almeida, A. K. A.; Monteiro, M. P.; Dias, J. M. M.; Omena, L.; da Silva, A. J. C.; Tonholo, J.; Mortimer, R. J.; Navarro, M.; Jacinto, C.; Ribeiro, A. S.; de Oliveira, I. N.

    2014-07-01

    The synthesis and fluorescence characterization of a new pyrrole derivative (PyPDG) containing the electron donor-acceptor dansyl substituent is reported. The effects of temperature and solvent polarity on the steady-state fluorescence of this compound are investigated. Our results show that PyPDG exhibits desirable fluorescent properties which makes it a promising candidate to be used as the photoactive material in optical thermometry and thermography applications. Further, the electrochemical and emission properties of polymeric films obtained from the oxidation polymerization of PyPDG are also analyzed.

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

    KAUST Repository

    Kronemeijer, Auke J.; Gili, Enrico; Shahid, Munazza; Rivnay, Jonathan; Salleo, Alberto; Heeney, Martin; Sirringhaus, Henning

    2012-01-01

    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. A review on chemistry of a powerful organic electron acceptor 7, 7, 8, 8, tetracynoquinodimethane (TCNQ)

    Science.gov (United States)

    Singh, Yadunath

    2018-05-01

    Organic semiconductors have so far found extensive practical applications similar to inorganic semiconductors. Interest in these compounds has been stimulated by the synthesis of several powerful electron acceptors, such as tetracynoethylene (TCNE), 7, 7, 8, 8, tetracynoquinodimethane (TCNQ) and cyno-p-benzoquinone. In this connection TCNQ is of particular interest, due to presence of four powerful electron accepting groups in its molecule. Nucleophillic addition reactions, which are rarely encountered among unsaturated compounds, as well as addition reactions proceeding via a one electron transfer stage are characteristic of this substance.

  1. 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...

  2. Donor-acceptor-pair emission characterization in N-B doped fluorescent SiC

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Kamiyama, Satoshi

    2011-01-01

    In the present work, we investigated donor-acceptor-pair emission in N-B doped fluorescent 6H-SiC, by means of photoluminescence, Raman spectroscopy, and angle-resolved photoluminescence. The photoluminescence results were interpreted by using a band diagram with Fermi-Dirac statistics. It is shown...... intensity in a large emission angle range was achieved from angle-resolved photoluminescence. The results indicate N-B doped fluorescent SiC as a good wavelength converter in white LEDs applications....

  3. High-Performance All-Polymer Solar Cells Achieved by Fused Perylenediimide-Based Conjugated Polymer Acceptors.

    Science.gov (United States)

    Yin, Yuli; Yang, Jing; Guo, Fengyun; Zhou, Erjun; Zhao, Liancheng; Zhang, Yong

    2018-05-09

    We report three n-type polymeric electron acceptors (PFPDI-TT, PFPDI-T, and PFPDI-Se) based on the fused perylene diimide (FPDI) and thieno[3,2- b]thiophene, thiophene, or selenophene units for all-polymer solar cells (all-PSCs). These FPDI-based polymer acceptors exhibit strong absorption between 350 and 650 nm with wide optical bandgap of 1.86-1.91 eV, showing good absorption compensation with the narrow bandgap polymer donor. The lowest unoccupied molecular orbital (LUMO) energy levels were located at around -4.11 eV, which are comparable with those of the fullerene derivatives and other small molecular electron acceptors. The conventional all-PSCs based on the three polymer acceptors and PTB7-Th as polymer donor gave remarkable power conversion efficiencies (PCEs) of >6%, and the PFPDI-Se-based all-PSC achieved the highest PCE of 6.58% with a short-circuit current density ( J sc ) of 13.96 mA/cm 2 , an open-circuit voltage ( V oc ) of 0.76 V, and a fill factor (FF) of 62.0%. More interestingly, our results indicate that the photovoltaic performances of the FPDI-based polymer acceptors are mainly determined by the FPDI unit with a small effect from the comonomers, which is quite different from the others reported rylenediimide-based polymer acceptors. This intriguing phenomenon is speculated as the huge geometry configuration of the FPDI unit, which minimizes the effect of the comonomer. These results highlight a promising future for the application of the FPDI-based polymer acceptors in the highly efficient all-PSCs.

  4. Enantioselective organocatalyzed Oxa-Michael-Aldol cascade reactions: Construction of chiral 4H-chromenes with a trifluoromethylated tetrasubstituted carbon stereocenter

    KAUST Repository

    Zhang, Jing; Ajitha, Manjaly John; He, Lin; Liu, Kai; Dai, Bin; Huang, Kuo-Wei

    2015-01-01

    The first organocatalytic asymmetric synthesis of 4H-chromenes bearing a trifluoromethylated tetrasubstituted carbon center is presented. Chiral secondary amines promote the oxa-Michael-aldol cascade reaction between alkynals and 2

  5. Why There Are Certain Parallels Between Joachim C. Fest’s Hitler-Biography and Michael Wolff’s Trump-Book

    Directory of Open Access Journals (Sweden)

    Christian Fuchs

    2018-02-01

    Full Text Available Joachim C. Fest published one of the most widely read Hitler biographies in 1973. Are there parallels of its analytical approach to Michael Wolff’s “Fire and Fury: Inside the Trump White House”?

  6. Acceptor Type Vacancy Complexes In As-Grown ZnO

    International Nuclear Information System (INIS)

    Zubiaga, A.; Tuomisto, F.; Zuniga-Perez, J.

    2010-01-01

    One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap (∼3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, Li Zn and Na Zn acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

  7. Free Carrier Generation in Fullerene Acceptors and Its Effect on Polymer Photovoltaics

    KAUST Repository

    Burkhard, George F.

    2012-12-20

    Early research on C60 led to the discovery that the absorption of photons with energy greater than 2.35 eV by bulk C60 produces free charge carriers at room temperature. We find that not only is this also true for many of the soluble fullerene derivatives commonly used in organic photovoltaics, but also that the presence of these free carriers has significant implications for the modeling, characterization, and performance of devices made with these materials. We demonstrate that the discrepancy between absorption and quantum efficiency spectra in P3HT:PCBM is due to recombination of such free carriers in large PCBM domains before they can be separated at a donor/acceptor interface. Since most theories assume that all free charges result from the separation of excitons at a donor/acceptor interface, the presence of free carrier generation in fullerenes can have a significant impact on the interpretation of data generated by numerous field-dependent techniques. © 2012 American Chemical Society.

  8. Site preference of Mg acceptors and improvement of p-type doping efficiency in nitride alloys.

    Science.gov (United States)

    Park, Ji-Sang; Chang, K J

    2013-06-19

    We perform first-principles density functional calculations to investigate the effect of Al and In on the formation energy and acceptor level of Mg in group-III nitride alloys. Our calculations reveal a tendency for the Mg dopants to prefer to occupy the lattice sites surrounded with Al atoms, whereas hole carriers are generated in In- or Ga-rich sites. The separation of the Mg dopants and hole carriers is energetically more favourable than a random distribution of dopants, being attributed to the local bonding effect of weak In and strong Al potentials in alloys. As a consequence, the Mg acceptor level, which represents the activation energy of Mg, tends to decrease with increasing numbers of Al next-nearest neighbours, whereas it increases as the number of In next-nearest neighbours increases. Based on the results, we suggest that the incorporation of higher Al and lower In compositions will improve the p-type doping efficiency in quaternary alloys, in comparison with GaN or AlGaN ternary alloys with similar band gaps.

  9. A method to quantify FRET stoichiometry with phasor plot analysis and acceptor lifetime ingrowth.

    Science.gov (United States)

    Chen, WeiYue; Avezov, Edward; Schlachter, Simon C; Gielen, Fabrice; Laine, Romain F; Harding, Heather P; Hollfelder, Florian; Ron, David; Kaminski, Clemens F

    2015-03-10

    FRET is widely used for the study of protein-protein interactions in biological samples. However, it is difficult to quantify both the FRET efficiency (E) and the affinity (Kd) of the molecular interaction from intermolecular FRET signals in samples of unknown stoichiometry. Here, we present a method for the simultaneous quantification of the complete set of interaction parameters, including fractions of bound donors and acceptors, local protein concentrations, and dissociation constants, in each image pixel. The method makes use of fluorescence lifetime information from both donor and acceptor molecules and takes advantage of the linear properties of the phasor plot approach. We demonstrate the capability of our method in vitro in a microfluidic device and also in cells, via the determination of the binding affinity between tagged versions of glutathione and glutathione S-transferase, and via the determination of competitor concentration. The potential of the method is explored with simulations. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Optical spacing effect in organic photovoltaic cells incorporating a dilute acceptor layer

    Energy Technology Data Exchange (ETDEWEB)

    Menke, S. Matthew; Lindsay, Christopher D.; Holmes, Russell J. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2014-06-16

    The addition of spacing layers in organic photovoltaic cells (OPVs) can enhance light absorption by optimizing the spatial distribution of the incident optical field in the multilayer structure. We explore the optical spacing effect in OPVs achieved using a diluted electron acceptor layer of C{sub 60}. While optical spacing is often realized by optimizing buffer layer thickness, we find that optical spacing via dilution leads to cells with similar or enhanced photocurrent. This is observed despite a smaller quantity of absorbing molecules, suggesting a more efficient use of absorbed photons. In fact, dilution is found to concentrate optical absorption near the electron donor-acceptor interface, resulting in a marked increase in the exciton diffusion efficiency. Contrasting the use of changes in thickness to engineer optical absorption, the use of dilution does not significantly alter the overall thickness of the OPV. Optical spacing via dilution is shown to be a viable alternative to more traditional optical spacing techniques and may be especially useful in the continued optimization of next-generation, tandem OPVs where it is important to minimize competition for optical absorption between individual sub-cells.

  11. General theory of excitation energy transfer in donor-mediator-acceptor systems.

    Science.gov (United States)

    Kimura, Akihiro

    2009-04-21

    General theory of the excitation energy transfer (EET) in the case of donor-mediator-acceptor system was constructed by using generalized master equation (GME). In this theory, we consider the direct and indirect transitions in the EET consistently. Hence, our theory includes the quantum mechanical interference between the direct and indirect transitions automatically. Memory functions in the GME were expressed by the overlap integrals among the time-dependent emission spectrum of the donor, the absorption spectrum of the mediator, the time-dependent emission spectrum of the mediator, and the absorption spectrum of the acceptor. In the Markov limit of the memory functions, we obtained the rate of EET which consists of three terms due to the direct transition, the indirect transition, and the interference between them. We found that the interference works effectively in the limit of slow thermalization at the intermediate state. The formula of EET rate in this limit was expressed by the convolution of the EET interaction and optical spectra. The interference effect strongly depends on the width of the absorption spectrum of mediator molecule and the energy gap between the donor and the mediator molecules.

  12. Free Carrier Generation in Fullerene Acceptors and Its Effect on Polymer Photovoltaics

    KAUST Repository

    Burkhard, George F.; Hoke, Eric T.; Beiley, Zach M.; McGehee, Michael D.

    2012-01-01

    Early research on C60 led to the discovery that the absorption of photons with energy greater than 2.35 eV by bulk C60 produces free charge carriers at room temperature. We find that not only is this also true for many of the soluble fullerene derivatives commonly used in organic photovoltaics, but also that the presence of these free carriers has significant implications for the modeling, characterization, and performance of devices made with these materials. We demonstrate that the discrepancy between absorption and quantum efficiency spectra in P3HT:PCBM is due to recombination of such free carriers in large PCBM domains before they can be separated at a donor/acceptor interface. Since most theories assume that all free charges result from the separation of excitons at a donor/acceptor interface, the presence of free carrier generation in fullerenes can have a significant impact on the interpretation of data generated by numerous field-dependent techniques. © 2012 American Chemical Society.

  13. Acceptor Type Vacancy Complexes In As-Grown ZnO

    Science.gov (United States)

    Zubiaga, A.; Tuomisto, F.; Zuñiga-Pérez, J.

    2010-11-01

    One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap (˜3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, LiZn and NaZn acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

  14. Magnetic thaw-down and boil-off due to magneto acceptors in 2DEG

    International Nuclear Information System (INIS)

    Chaubet, C.; Raymond, A.; Bisotto, I.; Harmand, J. C.; Kubisa, M.; Zawadzki, W.

    2013-01-01

    The Quantum Hall Effect (QHE) and Shubnikov-de Haas effect are investigated experimentally using n type modulation-doped GaAs/GaAlAs quantum wells (QWs) additionally doped in the well with beryllium acceptor atoms. It is presently shown that the localized magneto-acceptor (MA) states which possess discrete energies above the corresponding Landau levels (LLs) lead to two observable effects in magneto-transport: magnetic thaw-down and magnetic boil-off of 2D electrons. Both effects are related to the fact that electrons occupying the localized MA states cannot conduct. Thus in the thaw-down effect the electrons fall down from the MA states to the free Landau states. This leads to a shift of the Hall plateau towards higher magnetic fields as a consequence of an increase of the 2D electron density N S . In the boil-off effect the electrons are pushed from the free Landau states to the empty MA states under high enough Hall electric field. This process has an avalanche character leading to a dramatic increase of magneto-resistance, consequence of a decrease of N S

  15. Magnetic thaw-down and boil-off due to magneto acceptors in 2DEG

    Energy Technology Data Exchange (ETDEWEB)

    Chaubet, C.; Raymond, A. [L2C UMR 5221, CNRS-Université Montpellier 2, Place E. Bataillon, 34090 Montpellier cedex 05 (France); Bisotto, I. [LNCMI, UPR 3228, CNRS-INSA-UJF-UPS, BP166, 38042 Grenoble, Cedex 9 (France); Harmand, J. C. [LPN, CNRS, route de Nozay, 91460 Marcoussis (France); Kubisa, M. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw (Poland); Zawadzki, W. [Institute of Physics, Polish Academy of Sciences, 02668 Warsaw (Poland)

    2013-12-04

    The Quantum Hall Effect (QHE) and Shubnikov-de Haas effect are investigated experimentally using n type modulation-doped GaAs/GaAlAs quantum wells (QWs) additionally doped in the well with beryllium acceptor atoms. It is presently shown that the localized magneto-acceptor (MA) states which possess discrete energies above the corresponding Landau levels (LLs) lead to two observable effects in magneto-transport: magnetic thaw-down and magnetic boil-off of 2D electrons. Both effects are related to the fact that electrons occupying the localized MA states cannot conduct. Thus in the thaw-down effect the electrons fall down from the MA states to the free Landau states. This leads to a shift of the Hall plateau towards higher magnetic fields as a consequence of an increase of the 2D electron density N{sub S}. In the boil-off effect the electrons are pushed from the free Landau states to the empty MA states under high enough Hall electric field. This process has an avalanche character leading to a dramatic increase of magneto-resistance, consequence of a decrease of N{sub S}.

  16. Optical spacing effect in organic photovoltaic cells incorporating a dilute acceptor layer

    International Nuclear Information System (INIS)

    Menke, S. Matthew; Lindsay, Christopher D.; Holmes, Russell J.

    2014-01-01

    The addition of spacing layers in organic photovoltaic cells (OPVs) can enhance light absorption by optimizing the spatial distribution of the incident optical field in the multilayer structure. We explore the optical spacing effect in OPVs achieved using a diluted electron acceptor layer of C 60 . While optical spacing is often realized by optimizing buffer layer thickness, we find that optical spacing via dilution leads to cells with similar or enhanced photocurrent. This is observed despite a smaller quantity of absorbing molecules, suggesting a more efficient use of absorbed photons. In fact, dilution is found to concentrate optical absorption near the electron donor-acceptor interface, resulting in a marked increase in the exciton diffusion efficiency. Contrasting the use of changes in thickness to engineer optical absorption, the use of dilution does not significantly alter the overall thickness of the OPV. Optical spacing via dilution is shown to be a viable alternative to more traditional optical spacing techniques and may be especially useful in the continued optimization of next-generation, tandem OPVs where it is important to minimize competition for optical absorption between individual sub-cells.

  17. 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.

  18. 48-spot single-molecule FRET setup with periodic acceptor excitation

    Science.gov (United States)

    Ingargiola, Antonino; Segal, Maya; Gulinatti, Angelo; Rech, Ivan; Labanca, Ivan; Maccagnani, Piera; Ghioni, Massimo; Weiss, Shimon; Michalet, Xavier

    2018-03-01

    Single-molecule Förster resonance energy transfer (smFRET) allows measuring distances between donor and acceptor fluorophores on the 3-10 nm range. Solution-based smFRET allows measurement of binding-unbinding events or conformational changes of dye-labeled biomolecules without ensemble averaging and free from surface perturbations. When employing dual (or multi) laser excitation, smFRET allows resolving the number of fluorescent labels on each molecule, greatly enhancing the ability to study heterogeneous samples. A major drawback to solution-based smFRET is the low throughput, which renders repetitive measurements expensive and hinders the ability to study kinetic phenomena in real-time. Here we demonstrate a high-throughput smFRET system that multiplexes acquisition by using 48 excitation spots and two 48-pixel single-photon avalanche diode array detectors. The system employs two excitation lasers allowing separation of species with one or two active fluorophores. The performance of the system is demonstrated on a set of doubly labeled double-stranded DNA oligonucleotides with different distances between donor and acceptor dyes along the DNA duplex. We show that the acquisition time for accurate subpopulation identification is reduced from several minutes to seconds, opening the way to high-throughput screening applications and real-time kinetics studies of enzymatic reactions such as DNA transcription by bacterial RNA polymerase.

  19. The improved photovoltaic performance of phenothiazine-dithienopyrrole based dyes with auxiliary acceptors

    Science.gov (United States)

    Han, Ming-Liang; Zhu, Yi-Zhou; Liu, Shuang; Liu, Qing-Long; Ye, Dan; Wang, Bing; Zheng, Jian-Yu

    2018-05-01

    Incorporating alkyl chain decorated dithienopyrrole π-spacer with phenothiazine donor has proven to be efficient strategy for constructing novel dyes, which can achieve both large short-circuit current (Jsc) and high open-circuit voltage (Voc) in dye-sensitized solar cells (DSSCs). To promote the light harvesting capability, auxiliary acceptors including benzotriazole (BTZ), benzothiadiazole (BTD), and quinoxaline (Qu) have been inserted into the skeleton of dyes, and much improved Jsc have been realized. Meantime, the rational design of alkyl chains endows dyes JY53 and JY55 a good shielding effect from the penetration of electrolyte, guaranteeing a high Voc (over 810 mV) through retarding unwanted interfacial charge recombination. As a result, with the assistance of introduced auxiliary acceptors and alkyl chains, the photovoltaic performance of devices have been significantly improved, and dye JY55 has achieved an excellent power conversion efficiency (PCE) of 10.06% with Jsc of 19.18 mA cm-2, Voc of 829 mV, and FF of 0.63 under AM 1.5 G irradiation.

  20. 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. © 2018 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Optically tunable spin-exchange energy at donor:acceptor interfaces in organic solar cells

    International Nuclear Information System (INIS)

    Li, Mingxing; Wang, Hongfeng; He, Lei; Zang, Huidong; Xu, Hengxing; Hu, Bin

    2014-01-01

    Spin-exchange energy is a critical parameter in controlling spin-dependent optic, electronic, and magnetic properties in organic materials. This article reports optically tunable spin-exchange energy by studying the line-shape characteristics in magnetic field effect of photocurrent developed from intermolecular charge-transfer states based on donor:acceptor (P3HT:PCBM) system. Specifically, we divide magnetic field effect of photocurrent into hyperfine (at low field   10 mT) regimes. We observe that increasing photoexcitation intensity can lead to a significant line-shape narrowing in magnetic field effect of photocurrent occurring at the spin-exchange regime. We analyze that the line-shape characteristics is essentially determined by the changing rate of magnetic field-dependent singlet/triplet ratio when a magnetic field perturbs the singlet-triplet transition through spin mixing. Based on our analysis, the line-shape narrowing results indicate that the spin-exchange energy at D:A interfaces can be optically changed by changing photoexcitation intensity through the interactions between intermolecular charge-transfer states. Therefore, our experimental results demonstrate an optical approach to change the spin-exchange energy through the interactions between intermolecular charge-transfer states at donor:acceptor interface in organic materials.

  2. Thiophene-rich fused-aromatic thienopyrazine acceptor for donor–acceptor low band-gap polymers for OTFT and polymer solar cell applications

    KAUST Repository

    Mondal, Rajib

    2010-01-01

    Thiophene enriched fused-aromatic thieno[3,4-b]pyrazine systems were designed and employed to produce low band gap polymers (Eg = 1.0-1.4 eV) when copolymerized with fluorene and cyclopentadithiophene. The copolymers are mainly investigated for organic thin film transistor and organic photovoltaic applications. Molecular packing in the thin films of these polymers was investigated using Grazing incidence X-ray Scattering. Although both fluorene and cyclopentadithiophene polymers follow similar face to face π-π stacking, the latter polymers show much smaller lamellar d-spacings due to side-chain interdigitation between the lamellae. This lead to the higher charge carrier mobilities in cyclopentadithiophene polymers (up to 0.044 cm2/V.s) compared to fluorene polymers (up to 8.1 × 10-3 cm2/V.s). Power conversion efficiency of 1.4% was achieved using fluorene copolymer in solar cells with a fullerene derivative as an acceptor. Although the cyclopentadithiophene polymers show lower band gaps with higher absorption coefficients compared to fluorene copolymers, but the power conversion efficiencies in solar cells of these polymers are low due to their low ionization potentials. © The Royal Society of Chemistry 2010.

  3. Dye-Incorporated Polynaphthalenediimide Acceptor for Additive-Free High-Performance All-Polymer Solar Cells.

    Science.gov (United States)

    Chen, Dong; Yao, Jia; Chen, Lie; Yin, Jingping; Lv, Ruizhi; Huang, Bin; Liu, Siqi; Zhang, Zhi-Guo; Yang, Chunhe; Chen, Yiwang; Li, Yongfang

    2018-04-16

    All-polymer solar cells (all-PSCs) can offer unique advantages for applications in flexible devices, and naphthalene diimide (NDI)-based polymer acceptors are the widely used polymer acceptors. However, their power conversion efficiency (PCE) still lags behind that of state-of-the-art polymer solar cells, due to low light absorption, suboptimal energy levels and the strong aggregation of the NDI-based polymer acceptor. Herein, a rhodanine-based dye molecule was introduced into the NDI-based polymer acceptor by simple random copolymerization and showed an improved light absorption coefficient, an up-shifted lowest unoccupied molecular orbital level and reduced crystallization. Consequently, additive-free all-PSCs demonstrated a high PCE of 8.13 %, which is one of the highest performance characteristics reported for all-PSCs to date. These results indicate that incorporating a dye into the n-type polymer gives insight into the precise design of high-performance polymer acceptors for all-PSCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Effect of annealing on metastable shallow acceptors in Mg-doped GaN layers grown on GaN substrates

    OpenAIRE

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

    2008-01-01

    Mg-doped GaN layers grown by metal-organic vapor phase epitaxy on GaN substrates produced by the halide vapor phase technique demonstrate metastability of the near-band-gap photoluminescence (PL). The acceptor bound exciton (ABE) line possibly related to the C acceptor vanishes in as-grown samples within a few minutes under UV laser illumination. Annealing activates the more stable Mg acceptors and passivates C acceptors. Consequently, only the ABE line related to Mg is dominant in PL spectra...

  5. 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

  6. Crystallization and preliminary X-ray diffraction analysis of a tRNASer acceptor-stem microhelix

    International Nuclear Information System (INIS)

    Förster, Charlotte; Krauss, Norbert; Brauer, Arnd B. E.; Szkaradkiewicz, Karol; Brode, Svenja; Hennig, Klaus; Fürste, Jens P.; Perbandt, Markus; Betzel, Christian; Erdmann, Volker A.

    2006-01-01

    In order to investigate tRNA identity elements, an elongator tRNA Ser acceptor-stem helix was crystallized and a data set was collected to 1.8 Å resolution aiming at a comparison with the corresponding region in suppressor tRNA Sec . In order to understand elongator tRNA Ser and suppressor tRNA Sec identity elements, the respective acceptor-stem helices have been synthesized and crystallized in order to analyse and compare their structures in detail at high resolution. The synthesis, crystallization and preliminary X-ray diffraction results for a seven-base-pair tRNA Ser acceptor-stem helix are presented here. Diffraction data were collected to 1.8 Å, applying synchrotron radiation and cryogenic cooling. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 36.14, b = 38.96, c = 30.81 Å, β = 110.69°

  7. Trapped electron decay by the thermally-assisted tunnelling to electron acceptors in glassy matrices. A computer simulation study

    International Nuclear Information System (INIS)

    Feret, B.; Bartczak, W.M.; Kroh, J.

    1991-01-01

    The Redi-Hopefield quantum mechanical model of the thermally-assisted electron transfer has been applied to simulate the decay of trapped electrons by tunnelling to electron acceptor molecules added to the glassy matrix. It was assumed that the electron energy levels in donors and acceptors are statistically distributed and the electron excess energy after transfer is dissipated in the medium by the electron-phonon coupling. The electron decay curves were obtained by the method of computer simulation. It was found that for a given medium there exists a certain preferred value of the electronic excess energy which can be effectively converted into the matrix vibrations. If the mismatch of the electron states on the donor and acceptor coincides with the ''resonance'' energy the overall kinetics of electron transfer is accelerated. (author)

  8. 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....

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

    KAUST Repository

    Wadsworth, Andrew; Moser, Maximilian; Marks, Adam; Little, Mark S.; Gasparini, Nicola; Brabec, Christoph J.; Baran, Derya; McCulloch, Iain

    2018-01-01

    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.

  10. 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.

  11. The role of acceptor-rich domain in optoelectronic properties of photovoltaic diodes based on polymer blends

    Science.gov (United States)

    Dou, Fei; Silva, Carlos; Zhang, Xinping

    2013-09-01

    We investigate how the acceptor-rich domain influences the microstructure and photoluminescence properties, and consequently the external quantum efficiency of photovoltaic diodes based on blend films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(N,N'-diphenyl)-N,N'di(p-butyl-oxy-pheyl)-1,4-diaminobenzene)] (PFB) and poly[9,9-dioctylfluorenyl-2,7-diyl)-co-1,4-benzo-{2,1'-3}-thiadiazole)] (F8BT). We find that the interfacial area depends strongly on the size and density of acceptor- or F8BT-rich domains in the phase-separation scheme. There exists an optimized density and size distribution of the F8BT-rich domains, which favors spatial charge dissociation. Meanwhile, the balance of charge percolation between the donor(PFB)- and acceptor(F8BT)-rich domains also plays important roles in charge extraction and collection.

  12. Fused-Ring Acceptors with Asymmetric Side Chains for High-Performance Thick-Film Organic Solar Cells.

    Science.gov (United States)

    Feng, Shiyu; Zhang, Cai'e; Liu, Yahui; Bi, Zhaozhao; Zhang, Zhe; Xu, Xinjun; Ma, Wei; Bo, Zhishan

    2017-11-01

    A kind of new fused-ring electron acceptor, IDT-OB, bearing asymmetric side chains, is synthesized for high-efficiency thick-film organic solar cells. The introduction of asymmetric side chains can increase the solubility of acceptor molecules, enable the acceptor molecules to pack closely in a dislocated way, and form favorable phase separation when blended with PBDB-T. As expected, PBDB-T:IDT-OB-based devices exhibit high and balanced hole and electron mobility and give a high power conversion efficiency (PCE) of 10.12%. More importantly, the IDT-OB-based devices are not very sensitive to the film thickness, a PCE of 9.17% can still be obtained even the thickness of active layer is up to 210 nm. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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.

  14. 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.

  15. New eco-friendly animal bone meal catalysts for preparation of chalcones and aza-Michael adducts

    Directory of Open Access Journals (Sweden)

    Riadi Yassine

    2012-06-01

    Full Text Available Abstract Two efficient reactions were successfully carried out using Animal Bone Meal (ABM and potassium fluoride or sodium nitrate doped ABMs as new heterogeneous catalysts under very mild conditions. After preparation and characterization of the catalysts, we first report their use in a simple and convenient synthesis of various chalcones by Claisen–Schmidt condensation and then in an aza-Michael addition involving several synthesized chalcones with aromatic amines. All the reactions were carried out at room temperature in methanol; the chalcone synthesis was also achieved in water environment under microwave irradiation. Doping ABM enhances the rate and yield at each reaction. Catalytic activities are discussed and the ability to re-use the ABM is demonstrated. Results For Claisen–Schmidt the use of ABM alone, yields never exceeded 17%. In each entry, KF/ABM and NaNO3/ABM (79-97% gave higher yields than using ABM alone under thermic condition. Also the reaction proceeded under microwave irradiation in good yields (72-94% for KF/ABM and 81-97% for NaNO3/ABM and high purity. For aza-Michael addition the use of ABM doped with KF or NaNO3 increased the catalytic activity remarkably. The very high yields could be noted (84-95% for KF/ABM and 81-94% for NaNO3/ABM. Conclusion The present method is an efficient and selective procedure for the synthesis of chalcones an aza-Michael adducts. The ABM and doped ABMs are a new, inexpensive and attractive solid supports which can contribute to the development of catalytic processes and reduced environmental problems.

  16. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    Science.gov (United States)

    Ager, T.A.

    2003-01-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ???30,000 14C yr B.P. During the late middle Wisconsin interstadial (???30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows (Salix) and minor dwarf birch (Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ???30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca. 11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs (Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce (Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  17. Transglycosylation reactions of Bacillus stearothermophilus maltogenic amylase with acarbose and various acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Hwa Park, K; Jeong Kim, M; Seob Lee, H; Kim, D [Department of Food Science and Technology and Research Center for New Bio-Materials in Agriculture, Seoul National University, Suwon (Korea, Republic of); Soo Han, N; Robyt, J F [Laboratory for Carbohydrate Chemistry and Enzymology, Department of Biochemistry and Biophysics, Iowa State University, Ames, IA (United States)

    1998-12-15

    It was observed that Bacillus stearothermophilus maltogenic amylase cleaved the first glycosidic bond of acarbose to produce glucose and a pseudotrisaccharide (PTS) that was transferred to C-6 of the glucose to give an {alpha}-(1-6) glycosidic linkage and the formation of isoacarbose. The addition of a number of different carbohydrates to the digest gave transfer products in which PTS was primarily attached {alpha}-(1-6) to d-glucose, d-mannose, d-galactose, and methyl {alpha}-d-glucopyranoside. With d-fructopyranose and d-xylopyranose, PTS was linked {alpha}-(1-5) and {alpha}-(1-4), respectively. PTS was primarily transferred to C-6 of the nonreducing residue of maltose, cellobiose, lactose, and gentiobiose. Lesser amounts of {alpha}-(1-3) and/or {alpha}-(1-4) transfer products were also observed for these carbohydrate acceptors. The major transfer product to sucrose gave PTS linked {alpha}-(1-4) to the glucose residue. {alpha},{alpha}-Trehalose gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4). Maltitol gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4) to the glucopyranose residue. Raffinose gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4) to the d-galactopyranose residue. Maltotriose gave two major products with PTS linked {alpha}-(1-6) and {alpha}-(1-4) to the nonreducing end glucopyranose residue. Xylitol gave PTS linked {alpha}-(1-5) as the major product and d-glucitol gave PTS linked {alpha}-(1-6) as the only product. The structures of the transfer products were determined using thin layer-chromatography, high-performance ion chromatography, enzyme hydrolysis, methylation analysis and {sup 13}C NMR spectroscopy. The best acceptor was gentiobiose, followed closely by maltose and cellobiose, and the weakest acceptor was d-glucitol. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  18. Transglycosylation reactions of Bacillus stearothermophilus maltogenic amylase with acarbose and various acceptors

    International Nuclear Information System (INIS)

    Hwa Park, K.; Jeong Kim, M.; Seob Lee, H.; Kim, D.; Soo Han, N.; Robyt, J.F.

    1998-01-01

    It was observed that Bacillus stearothermophilus maltogenic amylase cleaved the first glycosidic bond of acarbose to produce glucose and a pseudotrisaccharide (PTS) that was transferred to C-6 of the glucose to give an α-(1-6) glycosidic linkage and the formation of isoacarbose. The addition of a number of different carbohydrates to the digest gave transfer products in which PTS was primarily attached α-(1-6) to d-glucose, d-mannose, d-galactose, and methyl α-d-glucopyranoside. With d-fructopyranose and d-xylopyranose, PTS was linked α-(1-5) and α-(1-4), respectively. PTS was primarily transferred to C-6 of the nonreducing residue of maltose, cellobiose, lactose, and gentiobiose. Lesser amounts of α-(1-3) and/or α-(1-4) transfer products were also observed for these carbohydrate acceptors. The major transfer product to sucrose gave PTS linked α-(1-4) to the glucose residue. α,α-Trehalose gave two major products with PTS linked α-(1-6) and α-(1-4). Maltitol gave two major products with PTS linked α-(1-6) and α-(1-4) to the glucopyranose residue. Raffinose gave two major products with PTS linked α-(1-6) and α-(1-4) to the d-galactopyranose residue. Maltotriose gave two major products with PTS linked α-(1-6) and α-(1-4) to the nonreducing end glucopyranose residue. Xylitol gave PTS linked α-(1-5) as the major product and d-glucitol gave PTS linked α-(1-6) as the only product. The structures of the transfer products were determined using thin layer-chromatography, high-performance ion chromatography, enzyme hydrolysis, methylation analysis and 13 C NMR spectroscopy. The best acceptor was gentiobiose, followed closely by maltose and cellobiose, and the weakest acceptor was d-glucitol. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  19. Michael additions of thiocompounds to {alpha}, {beta}-unsaturated carbonyl compounds in aqueous media: stereoselectivity with unambiguous characterization by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Queli Aparecida Rodrigues de; Pereira, Maria Luiza de Oliveira; Coelho, Ricardo Bezerra; Kaiser, Carlos Roland; Jones Junior, Joel; Silva, Flavia Martins da [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Organica]. E-mail: soa@iq.ufrj.br; Carvalho, Erika Martins de [Instituto de Tecnologia em Farmacos (Far-Manguinhos), Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The reactions of crotonaldehyde (8) with thiophenol (2) and benzalacetone (10) with ethane-1,2- dithiol (11) yield Michael addition products. The reactions of thiophenol (2) with (R)-carvone (13) and (S)-perillaldehyde (15) lead to (2S,3R,5S)-5-isopropenyl-2-methyl-3-(phenylthio)cyclohexanone (14) and (1R,2R,4S)-4-isopropenyl-2-(phenylthio)cyclohexanecarbaldehyde (16), respectively. An unambiguous elucidation of the stereochemistry of 14 and 16 by NMR is also presented. (author)

  20. Tandem Aldol-Michael Reactions in Aqueous Diethylamine Medium: A Greener and Efficient Approach to Bis-Pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Abdullah M. Al-Majid

    2013-12-01

    Full Text Available A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%.

  1. Kochin, Michael S. 2009. Five Chapters on Rhetoric: Character, Action, Things, Nothing and Art (University Park: Pennsylvania State University Press

    Directory of Open Access Journals (Sweden)

    Eithan Orkibi

    2010-04-01

    Full Text Available Deux constatations traversent le nouvel ouvrage de Michael Kochin, et nous invitent à reconsidérer la rhétorique dans la communication persuasive. D’abord, que ce sont les événements concrets et les faits mis à l’épreuve qui ont la plus grande force de conviction ; et ensuite, que le discours a souvent une fonction autre que la persuasion : celle de maintenir les canaux de communication pour sauvegarder les relations et les institutions humaines. Pour l’auteur de cet ouvrage qui porte sur les...

  2. A propósito del libro "Accounting theory: research, regulation and accounting practice" de Michael Gaffikin

    Directory of Open Access Journals (Sweden)

    Garcia Nohora

    2012-09-01

    Full Text Available En el libro “Accounting theory: research, regulation and accounting practice”, el profesor australiano Michael Gaffikin ofrece al lector una idea del origen y amplio desenvolvimiento de la teoría contable durante el siglo XX “cuyo desarrollo ha sido dominado por Estados Unidos” (Gaffikin, 2008, p. 32. Plantea, igualmente, los desafíos y problemas actuales de la regulación y la profesión contable. Por ejemplo, el autor precisa que ante la incapacidad de lograr un acuerdo sobre las mediciones apropiadas, la tendencia mundial es a instaurar medidas determinadas arbitrariamente (Gaffikin, 2008, p. 154.

  3. New 'Master of Science in Nuclear Engineering' study course launched. Interview with Professor Horst-Michael Prasser

    International Nuclear Information System (INIS)

    Anon.

    2008-01-01

    In the fall of 2008, the Zurich Technical University (ETH) and the Lausanne EPF will launch their joint master course of studies in Nuclear Engineering. Horst-Michael Prasser, Professor for Nuclear Energy Systems at Zurich ETH, is responsible for designing the course. In this interview he comments, among other things, on fundamental questions which may determine a future student's choice of a course of studies, and on the special opportunities offered by the new Nuclear Engineering course. Other subjects addressed include the renaissance of nuclear power and the future prospects of safety research and new reactor developments. (orig.)

  4. ‘Doxographical or Philosophical History of Philosophy: On Michael Frede’s Precepts for Writing the History of Philosophy’

    DEFF Research Database (Denmark)

    Catana, Leo

    2016-01-01

    In a series of articles from the 1980s and 1990s, Michael Frede analysed the history of histories of philosophy written over the last three hundred years. According to Frede, modern scholars have degenerated into what he calls a “doxographical” mode of writing the history of philosophy. Instead, he...... argued, these scholars should write what he called “philosophical” history of philosophy, first established in the last decades of the seventeenth century but since abandoned. In the present article it is argued that Frede’s reconstruction of the history of histories of philosophy is historically...

  5. Constructing Singapore : Elitism, Ethnicity and the Nation-Building Project, Michael D. Barr & Zlatko Skrbis

    Directory of Open Access Journals (Sweden)

    Jean-Louis Margolin

    2010-12-01

    Full Text Available Michael Barr, seul ou en collaboration, est depuis une décennie l’un des auteurs les plus prolifiques et les plus reconnus sur la structuration politique et sociologique du Singapour contemporain. Longtemps attaché à l’université du Queensland (Brisbane, aujourd’hui à Flinders (Adelaide, il est assez représentatif de la nouvelle génération (singapourienne aussi bien qu’étrangère des spécialistes de la cité-état : fermement critique, et parfois même hyper-critique, elle n’en reconnaît pas m...

  6. Advances in Statistical Control, Algebraic Systems Theory, and Dynamic Systems Characteristics A Tribute to Michael K Sain

    CERN Document Server

    Won, Chang-Hee; Michel, Anthony N

    2008-01-01

    This volume - dedicated to Michael K. Sain on the occasion of his seventieth birthday - is a collection of chapters covering recent advances in stochastic optimal control theory and algebraic systems theory. Written by experts in their respective fields, the chapters are thematically organized into four parts: Part I focuses on statistical control theory, where the cost function is viewed as a random variable and performance is shaped through cost cumulants. In this respect, statistical control generalizes linear-quadratic-Gaussian and H-infinity control. Part II addresses algebraic systems th

  7. 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.

  8. 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.

  9. High Performing Ternary Solar Cells through Förster Resonance Energy Transfer between Nonfullerene Acceptors.

    Science.gov (United States)

    Yang, Lei; Gu, Wenxing; Hong, Ling; Mi, Yang; Liu, Feng; Liu, Ming; Yang, Yufei; Sharma, Bigyan; Liu, Xinfeng; Huang, Hui

    2017-08-16

    Nonradiative Förster resonance energy transfer (FRET) is an important mechanism of organic solar cells, which can improve the exciton migration over a long distance, resulting in improvement of efficiency of solar cells. However, the current observations of FRET are very limited, and the efficiencies are less than 9%. In this study, FRET effect was first observed between two nonfullerene acceptors in ternary solar cells, which improved both the absorption range and exciton harvesting, leading to the dramatic enhancement in the short circuit current and power conversion efficiency. Moreover, this strategy is proved to be a versatile platform for conjugated polymers with different bandgaps, resulting in a remarkable efficiency of 10.4%. These results demonstrated a novel method to enhance the efficiency of organic soar cells.

  10. Thermal activation of nitrogen acceptors in ZnO thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Dangbegnon, J.K.; Talla, K.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth (South Africa)

    2010-06-15

    Nitrogen doping in ZnO is inhibited by spontaneous formation of compensating defects. Perfect control of the nitrogen doping concentration is required, since a high concentration of nitrogen could induce the formation of donor defects involving nitrogen. In this work, the effect of post-growth annealing in oxygen ambient on ZnO thin films grown by Metalorganic Chemical Vapor Deposition, using NO as both oxidant and nitrogen dopant, is studied. After annealing at 700 C and above, low-temperature photoluminescence shows the appearance of a transition at {proportional_to}3.23 eV which is interpreted as pair emission involving a nitrogen acceptor. A second transition at {proportional_to}3.15 eV is also discussed. This work suggests annealing as a potential means for p-type doping using nitrogen (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Excitation and recombination of donor-acceptor pairs in ZnTe

    International Nuclear Information System (INIS)

    Nakashima, S.; Yasuda, S.

    1979-01-01

    The photoluminescence spectra and its excitation spectra of the donor-acceptor pairs are observed in ZnTe crystals doped with Li and As in the region below the bandgap energy. The relaxation of electrons and holes into the first excited state of d-a pairs is studied for the three excitation processes: (1) bound-to-bound transitions, (2) bound-to-free transitions, and (3) free-to-free transitions. It is concluded that most of the electrons and holes at the excited states of each impurity level are relaxed rapidly into their ground states before the occurrence of the recombination involving the excited states. For the excitation process (2), conduction electrons are preferentially trapped by positively charged pairs. The redistribution of bound holes by hopping is suggested to explain the broad d-a emission band observed for the bound-to-free excitation for very distant pairs. (author)

  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

    By means of the positron lifetime technique we have measured positronium (Ps) yields in mixtures of nonpolar liquids with various electron scavengers which bind the electron fairly weakly (1–2 eV) in stable anions. The results are discussed with reference to recent excess electron works, and new...... experiments on anions and excess electrons are proposed. The minimum of the Ps yield versus CS2 concentration curves caused by partly delocalization of electrons on several scavenger molecules, which was observed previously in saturated aliphatic hydrocarbons occurred also in the saturated cyclic hydrocarbon...... 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...

  13. Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor–Acceptor Conjugated Polymers

    KAUST Repository

    Ayzner, Alexander L.; Mei, Jianguo; Appleton, Anthony; DeLongchamp, Dean; Nardes, Alexandre; Benight, Stephanie; Kopidakis, Nikos; Toney, Michael F.; Bao, Zhenan

    2015-01-01

    © 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.

  14. Complexes due to donor-acceptor-type transitions in GaAs

    International Nuclear Information System (INIS)

    Reynolds, D.C.; Litton, C.W.; Almassy, R.J.; McCoy, G.L.; Nam, S.B.

    1980-01-01

    A sharp line transition at 1.51385 eV has been observed in the photoluminescence spectra of an epitaxially grown crystal of GaAs. A Si 3 N 4 cap was applied by plasma deposition and the crystal was then annealed at 850 0 C for 15 min. The sharp emission line was observed after annealing. This transition was analyzed in perturbing magnetic and strain fields and is shown to result from a donor-acceptor-type complex. Three additional sharp line transitions are reported and the behavior of all of these transitions is compared with the behavior of similar transitions reported in the literature. Models for the complexes involved are re-examined and components of the complexes are suggested. All of the sharp line transitions were introduced in the growing process with the exception of the 1.51385-eV line which was introduced in the capping and annealing process

  15. Economical and accurate protocol for calculating hydrogen-bond-acceptor strengths.

    Science.gov (United States)

    El Kerdawy, Ahmed; Tautermann, Christofer S; Clark, Timothy; Fox, Thomas

    2013-12-23

    A series of density functional/basis set combinations and second-order Møller-Plesset calculations have been used to test their ability to reproduce the trends observed experimentally for the strengths of hydrogen-bond acceptors in order to identify computationally efficient techniques for routine use in the computational drug-design process. The effects of functionals, basis sets, counterpoise corrections, and constraints on the optimized geometries were tested and analyzed, and recommendations (M06-2X/cc-pVDZ and X3LYP/cc-pVDZ with single-point counterpoise corrections or X3LYP/aug-cc-pVDZ without counterpoise) were made for suitable moderately high-throughput techniques.

  16. Spectroscopic studies on novel donor-acceptor and low band-gap polymeric semiconductors

    International Nuclear Information System (INIS)

    Cravino, A.

    2002-11-01

    Novel low band-gap conjugated polymeric semiconductors as well as conjugated electron donor chains carrying electron acceptor substituents were electrochemically prepared and investigated by means of different spectroscopic techniques. Using in situ FTIR and ESR spectroelectrochemistry, the spectroscopic features of injected positive charges are found to be different as opposed to the negative charge carriers on the same conjugated polymer. These results, for which the theoretical models so far developed do not account, demonstrate the different structure and delocalization of charge carriers with opposite signs. In addition, vibrational spectroscopy results proof the enhanced 'quinoid' character of low band-gap conjugated chains. Excited state spectroscopy was applied to study photoexcitations in conjugated polymers carrying tetracyanoanthraquinone type or fullerene moieties. This novel class of materials, hereafter called double-cable polymers, was found promising as alternative to the conjugated polymer:fullerene mixtures currently used for the preparation of 'bulk-heterojunction' polymeric solar cells. (author)

  17. Generation of a Multicomponent Library of Disulfide Donor-Acceptor Architectures Using Dynamic Combinatorial Chemistry.

    Science.gov (United States)

    Drożdż, Wojciech; Kołodziejski, Michał; Markiewicz, Grzegorz; Jenczak, Anna; Stefankiewicz, Artur R

    2015-07-17

    We describe here the generation of new donor-acceptor disulfide architectures obtained in aqueous solution at physiological pH. The application of a dynamic combinatorial chemistry approach allowed us to generate a large number of new disulfide macrocyclic architectures together with a new type of [2]catenanes consisting of four distinct components. Up to fifteen types of structurally-distinct dynamic architectures have been generated through one-pot disulfide exchange reactions between four thiol-functionalized aqueous components. The distribution of disulfide products formed was found to be strongly dependent on the structural features of the thiol components employed. This work not only constitutes a success in the synthesis of topologically- and morphologically-complex targets, but it may also open new horizons for the use of this methodology in the construction of molecular machines.

  18. Superposition of two tRNASer acceptor stem crystal structures: Comparison of structure, ligands and hydration

    International Nuclear Information System (INIS)

    Eichert, Andre; Fuerste, Jens P.; Ulrich, Alexander; Betzel, Christian; Erdmann, Volker A.; Foerster, Charlotte

    2010-01-01

    We solved the X-ray structures of two Escherichia coli tRNA Ser acceptor stem microhelices. As both tRNAs are aminoacylated by the same seryl-tRNA-synthetase, we performed a comparative structure analysis of both duplexes to investigate the helical conformation, the hydration patterns and magnesium binding sites. It is well accepted, that the hydration of RNA plays an important role in RNA-protein interactions and that the extensive solvent content of the minor groove has a special function in RNA. The detailed comparison of both tRNA Ser microhelices provides insights into the structural arrangement of the isoacceptor tRNA aminoacyl stems with respect to the surrounding water molecules and may eventually help us to understand their biological function at atomic resolution.

  19. Isolation by crystallization of translational isomers of a bistable donor-acceptor [2]catenane

    Science.gov (United States)

    Wang, Cheng; Olson, Mark A.; Fang, Lei; Benítez, Diego; Tkatchouk, Ekaterina; Basu, Subhadeep; Basuray, Ashish N.; Zhang, Deqing; Zhu, Daoben; Goddard, William A.; Stoddart, J. Fraser

    2010-01-01

    The template-directed synthesis of a bistable donor-acceptor [2]catenane wherein both translational isomers—one in which a tetrathiafulvalene unit in a mechanically interlocked crown ether occupies the cavity of a cyclobis(paraquat-p-phenylene) ring and the other in which a 1,5-dioxynaphthalene unit in the crown ether resides inside the cavity of the tetracationic cyclophane—exist in equilibrium in solution, has led to the isolation and separation by hand picking of single crystals colored red and green, respectively. These two crystalline co-conformations have been characterized separately at both the molecular and supramolecular levels, and also by dynamic NMR spectroscopy in solution where there is compelling evidence that the mechanically interlocked molecules are present as a complex mixture of translational, configurational, and conformational isomers wherein the isomerization is best described as being a highly dynamic and adaptable phenomenon. PMID:20663950

  20. Hopping ladder and power relaxation due to donor-acceptor pairs

    International Nuclear Information System (INIS)

    Kostadinov, I.Z.

    1985-11-01

    Hopping between donor-acceptor pairs leads to peculiar temperature dependence of the conductivity and the photoconductivity under subband gap illumination in the form of non-linear activation energies ladder. The correlated and uncorrelated distributions of pairs are considered and the conditions for the ladder existence are determined. The relaxation of the carrier concentration fluctuations is studied and power type decay is found. The temperature dependence of the exponent is calculated in agreement with the non-exponential decay of the pulse excited luminescence observed by Dean et al. The temperature dependence of the luminescence intensity also shows variable activation energy as found here. The exponent value α=1.316 is also in agreement with the data for crystalline and amorphous materials. (author)

  1. Shape-Tunable Charge Carrier Dynamics at the Interfaces between Perovskite Nanocrystals and Molecular Acceptors

    KAUST Repository

    Ahmed, Ghada H.

    2016-09-19

    Hybrid organic/inorganic perovskites have recently emerged as an important class of materials and have exhibited remarkable performance in photovoltaics. To further improve their device efficiency, an insightful understanding of the interfacial charge transfer (CT) process is required. Here, we report the first direct experimental observation of the tremendous effect that the shape of perovskite nanocrystals (NCs) has on interfacial CT in the presence of a molecular acceptor. A dramatic change in CT dynamics at the interfaces of three different NC shapes, spheres, platelets, and cubes, is recorded. Our results clearly demonstrate that the mechanism of CT is significantly affected by the NC shape. More importantly, the results demonstrate that complexation on the NC surface acts as an additional driving force not only to tune the CT dynamics but also to control the reaction mechanism at the interface. This observation opens a new venue for further developing perovskite NCs-based applications.

  2. Dissipative exciton transfer in donor-bridge-acceptor systems: numerical renormalization group calculation of equilibrium properties

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, Sabine [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg (Germany); Tong, Ning-Hua [Institut fuer Theorie der Kondensierten Materie, Universitaet Karlsruhe, 76128 Karlsruhe (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg (Germany)

    2006-07-05

    We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows one to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems with up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.

  3. Dissipative exciton transfer in donor-bridge-acceptor systems: numerical renormalization group calculation of equilibrium properties.

    Science.gov (United States)

    Tornow, Sabine; Tong, Ning-Hua; Bulla, Ralf

    2006-07-05

    We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows one to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems with up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.

  4. 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.

  5. Shape-Tunable Charge Carrier Dynamics at the Interfaces between Perovskite Nanocrystals and Molecular Acceptors

    KAUST Repository

    Ahmed, Ghada H.; Liu, Jiakai; Parida, Manas R.; Banavoth, Murali; Bose, Riya; AlYami, Noktan; Hedhili, Mohamed N.; Peng, Wei; Pan, Jun; Besong, Tabot M.D.; Bakr, Osman; Mohammed, Omar F.

    2016-01-01

    Hybrid organic/inorganic perovskites have recently emerged as an important class of materials and have exhibited remarkable performance in photovoltaics. To further improve their device efficiency, an insightful understanding of the interfacial charge transfer (CT) process is required. Here, we report the first direct experimental observation of the tremendous effect that the shape of perovskite nanocrystals (NCs) has on interfacial CT in the presence of a molecular acceptor. A dramatic change in CT dynamics at the interfaces of three different NC shapes, spheres, platelets, and cubes, is recorded. Our results clearly demonstrate that the mechanism of CT is significantly affected by the NC shape. More importantly, the results demonstrate that complexation on the NC surface acts as an additional driving force not only to tune the CT dynamics but also to control the reaction mechanism at the interface. This observation opens a new venue for further developing perovskite NCs-based applications.

  6. New splice site acceptor mutation in AIRE gene in autoimmune polyendocrine syndrome type 1.

    Directory of Open Access Journals (Sweden)

    Mireia Mora

    Full Text Available Autoimmune polyglandular syndrome type 1 (APS-1, OMIM 240300 is a rare autosomal recessive disorder, characterized by the presence of at least two of three major diseases: hypoparathyroidism, Addison's disease, and chronic mucocutaneous candidiasis. We aim to identify the molecular defects and investigate the clinical and mutational characteristics in an index case and other members of a consanguineous family. We identified a novel homozygous mutation in the splice site acceptor (SSA of intron 5 (c.653-1G>A in two siblings with different clinical outcomes of APS-1. Coding DNA sequencing revealed that this AIRE mutation potentially compromised the recognition of the constitutive SSA of intron 5, splicing upstream onto a nearby cryptic SSA in intron 5. Surprisingly, the use of an alternative SSA entails the uncovering of a cryptic donor splice site in exon 5. This new transcript generates a truncated protein (p.A214fs67X containing the first 213 amino acids and followed by 68 aberrant amino acids. The mutation affects the proper splicing, not only at the acceptor but also at the donor splice site, highlighting the complexity of recognizing suitable splicing sites and the importance of sequencing the intron-exon junctions for a more precise molecular diagnosis and correct genetic counseling. As both siblings were carrying the same mutation but exhibited a different APS-1 onset, and one of the brothers was not clinically diagnosed, our finding highlights the possibility to suspect mutations in the AIRE gene in cases of childhood chronic candidiasis and/or hypoparathyroidism otherwise unexplained, especially when the phenotype is associated with other autoimmune diseases.

  7. Combined Oral Contraceptive Pills: Profile of Acceptors in a Tertiary Hospital in South-South Nigeria.

    Science.gov (United States)

    Abasiattai, A M; Utuk, M N; Ojeh, S O; Eyo, U E

    2011-01-01

    BACKGROUND: Combined oral contraceptive pills were the first contraceptive method to provide sexual freedom of choice for women through reliable, personal and private control of fertility. They are the most widely used hormonal contraceptives and also the most popular non-surgical method of contraception. OBJECTIVE: To review the profile of acceptors of combined oral contraceptive pills at the University of Uyo Teaching Hospital, Uyo. METHODOLOGY: An 8 year review of all clients that accepted combined oral contraceptive pills in the family planning clinic. RESULTS: There were 1,146 new contraceptive acceptors during the period of study out of which 309 (27.9%) accepted the pills. Majority of the clients were between 20 and 29 years of age (54.0%), were multiparous (72.8%), Christians (99.7%) and 61.2% had tertiary level education. Two hundred and fifty-five women (82.5%) desired to use combined oral contraceptive pills to space births while 7.8% wanted to limit child bearing. There was a high discontinuation rate among the women (45.0%) and out of these 87.9% of the clients changed to other contraceptive methods. All the clients commenced their pills within seven days of menstruation and only the low dose monophasic preparations were available in the family planning unit and thus were given to the clients. CONCLUSION: Women who accept to initiate combined oral contraceptive pills in our center are young, well educated, multiparous women who want to space their pregnancies. However, due to the high discontinuation rate among the clients, there is need for further studies evaluating reasons for the high discontinuation rate, exploring interactions between clients and providers' and also providers' attitude towards combined pills in our environment.

  8. 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.

  9. 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.

  10. Trajetória acadêmica e perspectivas acerca do turismo sob o olhar de Colin Michael Hall

    Directory of Open Access Journals (Sweden)

    Elayne Gouveia da Silva

    2016-04-01

    Full Text Available Este trabalho versa sobre a visão do Colin Michael Hall na temática do turismo. Para analisar essa temática imbricou-se em duas leituras principais como parâmetro para a discussão. A primeira é a obra “Planejamento turístico: política, processo e planejamento” e, a segunda, “Turismo como El Ciencia Social de La Movilidade”. Estas obras marcam a mudança de visão do autor, onde o mesmo se dedica a fomentar um novo olhar sobre o turismo suscitando sete aspectos para se pensar no turismo. O objetivo deste artigo é analisar a visão de Colin Michael Hall acerca do Turismo. Como metas intermediárias pretende-se, a partir da compilação de informações sobre sua vida acadêmica e suas principais contribuições realizar uma breve crítica. Para o trabalho utilizou-se a pesquisa bibliográfica, e entrevista com o autor. Como resultado obteve-se uma reunião das principais ideias e posições ideológicas do autor, e algumas de suas contribuições com o estudo do turismo.

  11. Synthesis of l-threitol-based crown ethers and their application as enantioselective phase transfer catalyst in Michael additions.

    Science.gov (United States)

    Rapi, Zsolt; Nemcsok, Tamás; Pálvölgyi, Ádám; Keglevich, György; Grün, Alajos; Bakó, Péter

    2017-06-01

    A few new l-threitol-based lariat ethers incorporating a monoaza-15-crown-5 unit were synthesized starting from diethyl l-tartrate. These macrocycles were used as phase transfer catalysts in asymmetric Michael addition reactions under mild conditions to afford the adducts in a few cases in good to excellent enantioselectivities. The addition of 2-nitropropane to trans-chalcone, and the reaction of diethyl acetamidomalonate with β-nitrostyrene resulted in the chiral Michael adducts in good enantioselectivities (90% and 95%, respectively). The substituents of chalcone had a significant impact on the yield and enantioselectivity in the reaction of diethyl acetoxymalonate. The highest enantiomeric excess (ee) values (99% ee) were measured in the case of 4-chloro- and 4-methoxychalcone. The phase transfer catalyzed cyclopropanation reaction of chalcone and benzylidene-malononitriles using diethyl bromomalonate as the nucleophile (MIRC reaction) was also developed. The corresponding chiral cyclopropane diesters were obtained in moderate to good (up to 99%) enantioselectivities in the presence of the threitol-based crown ethers. © 2017 Wiley Periodicals, Inc.

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

    KAUST Repository

    Cha, Hyojung; Wheeler, Scot; Holliday, Sarah; Dimitrov, Stoichko D.; Wadsworth, Andrew; Lee, Hyun Hwi; Baran, Derya; McCulloch, Iain; Durrant, James R.

    2017-01-01

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

  13. The interaction of quinones, herbicides and bicarbonate with their binding environment at the acceptor side of photosystem II in photosynthesis

    NARCIS (Netherlands)

    Vermaas, W.F.J.

    1984-01-01

    In this thesis experiments are described which are directed towards a further characterization of the interaction of the native bound plastoquinone Q B , artificial quinones, herbicides and bicarbonate with their binding environment at the acceptor side of Photosystem II in

  14. Characterization of a spectrally diverse set of fluorescent proteins as FRET acceptors for mTurquoise2

    NARCIS (Netherlands)

    Mastop, M.; Bindels, D.S.; Shaner, N.C.; Postma, M.; Gadella, T.W.J.; Goedhart, J.

    2017-01-01

    The performance of Förster Resonance Energy Transfer (FRET) biosensors depends on brightness and photostability, which are dependent on the characteristics of the fluorescent proteins that are employed. Yellow fluorescent protein (YFP) is often used as an acceptor but YFP is prone to photobleaching

  15. Resonant and non-resonant components of the rate of a population transfer in hybrid donor-acceptor systems

    Czech Academy of Sciences Publication Activity Database

    Menšík, Miroslav; Král, Karel

    2013-01-01

    Roč. 5, č. 6 (2013), s. 565-568 ISSN 2164-6627 R&D Projects: GA MŠk(CZ) OC10007; GA MŠk LH12186; GA ČR(CZ) GAP205/10/2280 Institutional support: RVO:61389013 ; RVO:68378271 Keywords : energy transfer * hybrid donor-acceptor system Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. 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.

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

    KAUST Repository

    Cha, Hyojung

    2017-11-27

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

  18. Wide-range light-harvesting donor-acceptor assemblies through specific intergelator interactions via self-assembly.

    Science.gov (United States)

    Samanta, Suman K; Bhattacharya, Santanu

    2012-12-03

    We have synthesized two new low-molecular-mass organogelators based on tri-p-phenylene vinylene derivatives, one of which could be designated as the donor whereas the other one is an acceptor. These were prepared specifically to show the intergelator interactions at the molecular level by using donor-acceptor self-assembly to achieve appropriate control over their macroscopic properties. Intermolecular hydrogen-bonding, π-stacking, and van der Waals interactions operate for both the individual components and the mixtures, leading to the formation of gels in the chosen organic solvents. Evidence for intergelator interactions was acquired from various spectroscopic, microscopic, thermal, and mechanical investigations. Due to the photochromic nature of these molecules, interesting photophysical properties, such as solvatochromism and J-type aggregation, were clearly observed. An efficient energy transfer was exhibited by the mixture of donor-acceptor assemblies. An array of four chromophores was built up by inclusion of two known dyes (anthracene and rhodamine 6G) for the energy-transfer studies. Interestingly, an energy-transfer cascade was observed in the assembly of four chromophores in a particular order (anthracene-donor-acceptor-rhodamine 6G), and if one of the components was removed from the assembly the energy transfer process was discontinued. This allowed the build up of a light-harvesting process with a wide range. Excitation at one end produces an emission at the other end of the assembly. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Understanding charge transport and recombination losses in high performance polymer solar cells with non-fullerene acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xuning [HEEGER Beijing Research & Development Center; School of Chemistry; Beihang University; Beijing 100191; China; Zuo, Xiaobing [X-ray Science Division; Argonne National Laboratory; Argonne; USA; Xie, Shenkun [HEEGER Beijing Research & Development Center; School of Chemistry; Beihang University; Beijing 100191; China; Yuan, Jianyu [Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices; Institute of Functional Nano & Soft Materials (FUNSOM); Soochow University; Suzhou; P. R. China; Zhou, Huiqiong [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication; CAS Center for Excellence in Nanoscience; National Center for Nanoscience and Technology; Beijing 100190; China; Zhang, Yuan [HEEGER Beijing Research & Development Center; School of Chemistry; Beihang University; Beijing 100191; China

    2017-01-01

    Photovoltaic characteristics, recombination and charge transport properties are investigated. The determined recombination reduction factor can reconcile the supreme device performance in organic solar cells using non-fullerene ITIC acceptor and severe carrier losses in all-polymer devices with P(NDI2OD-T2).

  20. Single and double acceptor-levels of a carbon-hydrogen defect in n-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Stübner, R.; Scheffler, L.; Kolkovsky, Vl., E-mail: kolkov@ifpan.edu.pl; Weber, J. [Technische Universität Dresden, 01062 Dresden (Germany)

    2016-05-28

    In the present study, we discuss the origin of two dominant deep levels (E42 and E262) observed in n-type Si, which is subjected to hydrogenation by wet chemical etching or a dc H-plasma treatment. Their activation enthalpies determined from Laplace deep level transient spectroscopy measurements are E{sub C}-0.06 eV (E42) and E{sub C}-0.51 eV (E262). The similar annealing behavior and identical depth profiles of E42 and E262 correlate them with two different charge states of the same defect. E262 is attributed to a single acceptor state due to the absence of the Poole-Frenkel effect and the lack of a capture barrier for electrons. The emission rate of E42 shows a characteristic enhancement with the electric field, which is consistent with the assignment to a double acceptor state. In samples with different carbon and hydrogen content, the depth profiles of E262 can be explained by a defect with one H-atom and one C-atom. From a comparison with earlier calculations [Andersen et al., Phys. Rev. B 66, 235205 (2002)], we attribute E42 to the double acceptor and E262 to the single acceptor state of the CH{sub 1AB} configuration, where one H atom is directly bound to carbon in the anti-bonding position.