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Sample records for charge conjugation atio

  1. On charge conjugation

    International Nuclear Information System (INIS)

    The group of automorphisms of the conformal algebra su(2,2) has four components giving the usual four components of symmetries of space time. Only two of these components extend to symmetries of the conformal superalgebra - the identity component and the component which induces the parity transformation, P, on space time. There is no automorphism of the conformal superalgebra which induces T or PT on space time. Automorphisms of su(2,2) which belong to these last two components induce transformations on the conformal superalgebra which reverse the sign of the odd brackets. In this sense conformal supersymmetry prefers CP to CPT. The operator of charge conjugation acting on spinors, as is found in the standard texts, induces conformal inversion and hence a parity transformation on space time, when considered as acting on the odd generators of the conformal superalgebra. Although it commutes with Lorentz transformations, it does not commute with all of su(2,2). We propose a different operator for charge conjugation. Geometrically it is induced by the Hodge star operator acting on twistor space. Under the known realization of conformal states from the inclusion SU(2,2)→Sp(8) and the metaplectic representations, its action on states is induced by the unique (up to phase) antilinear intertwining operator between the two metaplectic representations. It is consistent with the split orthosymplectic algebras and hence, by the inclusion of the superconformal in the orthosymplectic, with the orthosymplectic algebra. (orig.)

  2. Charge Conjugation in the Galilean Limit

    OpenAIRE

    Socolovsky, Miguel

    2006-01-01

    Strictly working in the framework of the nonrelativistic quantum mechanics of a spin 1/2 particle coupled to an external electromagnetic field, we show, by explicit construction, the existence of a charge conjugation operator matrix which defines the corresponding antiparticle wave function and leads to the galilean and gauge invariant Schroedinger-Pauli equation satisfied by it.

  3. A Charge-Conjugation-Invariance Constrained Pomeron-Quark Coupling

    OpenAIRE

    Liu, Lon-chang

    2005-01-01

    The commonly used $\\gamma_{\\mu}} Pomeron-quark coupling changes its sign under charge conjugation, in contradiction to the property of Pomeron. I show that the Pomeron-quark coupling is tensorial and is invariant under the charge conjugation.

  4. Gauge Transformations For Self/Anti-Self Charge Conjugate States

    CERN Document Server

    Dvoeglazov, V V

    1998-01-01

    Gauge transformations of type-II spinors are considered in the Majorana-Ahluwalia construct for self/anti-self charge conjugate states. Some speculations on the relations of this model with the earlier ones are given.

  5. Some properties of charge-conjugated spinors in D dimensions

    CERN Document Server

    D'Andrade, M A

    1995-01-01

    Spinors for an arbitrary Minkowski space with signature (t, s) are reassessed in connection with D-dimensional free Dirac action. The possibility of writing down kinetic and mass terms for charge-conjugated spinors is discussed in terms of the number of time-like directions of the space-time.

  6. Conformation sensitive charge transport in conjugated polymers

    OpenAIRE

    Andersson, Mattias; Hedstrom, Svante; Persson, Petter

    2013-01-01

    Temperature dependent charge carrier mobility measurements using field effect transistors and density functional theory calculations are combined to show how the conformation dependent frontier orbital delocalization influences the hole-and electron mobilities in a donor-acceptor based polymer. A conformationally sensitive lowest unoccupied molecular orbital results in an electron mobility that decreases with increasing temperature above room temperature, while a conformationally stable highe...

  7. Relativistic invariance and charge conjugation in quantum field theory

    International Nuclear Information System (INIS)

    We prove that superselection sectors with finite statistics in the sense of Doplicher, Haag, and Roberts are automatically Poincare covariant under natural conditions (e.g. split property for space-like cones and duality for contractible causally complete regions). The same holds for topological charges, namely sectors localized in space-like cones, providing a converse to a theorem of Buchholz and Fredenhagen. We introduce the notion of weak conjugate sector that turns out to be equivalent to the DHR conjugate in finite statistics. The weak conjugate sector is given by an explicit formula that relates it to the PCT symmetry in a Wightman theory. Every Euclidean covariant sector (possibly with infinite statistics) has a weak conjugate sector and the converse is true under the above natural conditions. On the same basis, translation covariance is equivalent to the property that sectors are sheaf maps modulo inner automorphisms, for a certain sheaf structure given by the local algebras. The construction of the weak conjugate sector extends to the case of local algebras on S1, conformal theories in particular. Our main tools are the Bisognano-Wichmann description of the modular structure of the von Neumann algebras associated with wedge regions in the vacuum sector and the relation between Jones index theory for subfactors and the statistics of superselection sectors. (orig.)

  8. Charge conjugation and Lense-Thirring Effect: A new Asymmetry

    CERN Document Server

    Ahluwalia-Khalilova, D V

    2004-01-01

    This essay presents a new asymmetry that arises from the interplay of charge conjugation and Lense-Thirring effect. When applied to Majorana neutrinos, the effects predicts nu_e overline{nu}_e oscillations in gravitational environments with rotating sources. Parameters associated with astrophysical environments indicate that the presented effect is presently unobservable for solar neutrinos. But, it will play an important role in supernova explosions, and carries relevance for the observed matter-antimatter asymmetry in the universe.

  9. Charge-conjugation invariance of the spectator equations

    International Nuclear Information System (INIS)

    In response to recent criticism, we show how to define the spectator equations for negative energies so that charge-conjugation invariance is preserved. The results, which emerges naturally from the application of spectator principles to systems of particles with negative energies, is to replace all factors of the external energies Wi by Wi2, insuring that the amplitudes are independent of the sign of the energies Wi. (author)

  10. Remark on Charge Conjugation in the Non Relativistic Limit

    Science.gov (United States)

    Cabo, A.; Cervantes, D. B.; Rojas, H. Pérez; Socolovsky, M.

    2006-05-01

    We study the non relativistic limit of the charge conjugation operation $\\cal C$ in the context of the Dirac equation coupled to an electromagnetic field. The limit is well defined and, as in the relativistic case, $\\cal C$, $\\cal P$ (parity) and $\\cal T$ (time reversal) are the generators of a matrix group isomorphic to a semidirect sum of the dihedral group of eight elements and $\\Z_2$. The existence of the limit is supported by an argument based in quantum field theory. Also, and most important, the limit exists in the context of galilean relativity. Finally, if one complexifies the Lorentz group and therefore the galilean spacetime $x_\\mu$, then the explicit form of the matrix for $\\cal C$ allows to interpret it, in this context, as the complex conjugation of the spatial coordinates: $\\vec{x} \\to \\vec{x}^*$. This result is natural in a fiber bundle description.

  11. The Optical Signature of Charges in Conjugated Polymers.

    Science.gov (United States)

    Heimel, Georg

    2016-05-25

    Electrical charge flowing through organic semiconductors drives many of today's mobile phone displays and television screens, suggesting an internally consistent model of charge-carrier properties in these materials to have manifested. In conjugated polymers, charges give rise to additional absorption of light at wavelengths longer than those absorbed by the electrically neutral species. These characteristic absorption bands are universally being related to the emergence of localized energy levels shifted into the forbidden gap of organic semiconductors due to local relaxation of the molecular geometry. However, the traditional view on these energy levels and their occupation is incompatible with expected changes in electron removal and addition energies upon charging molecules. Here, I demonstrate that local Coulomb repulsion, as captured by nonempirically optimized electronic-structure calculations, restores compatibility and suggests a different origin of the charge-induced optical transitions. These results challenge a widely accepted and long-established picture, but an improved understanding of charge carriers in molecular materials promises a more targeted development of organic and hybrid organic/inorganic (opto-)electronic devices. PMID:27280165

  12. Remark on charge conjugation in the non relativistic limit

    OpenAIRE

    Cabo, A.; Cervantes, D. B.; Rojas, H. Perez; Socolovsky, M.

    2005-01-01

    We study the non relativistic limit of the charge conjugation operation $\\cal C$ in the context of the Dirac equation coupled to an electromagnetic field. The limit is well defined and, as in the relativistic case, $\\cal C$, $\\cal P$ (parity) and $\\cal T$ (time reversal) are the generators of a matrix group isomorphic to a semidirect sum of the dihedral group of eight elements and $\\Z_2$. The existence of the limit is supported by an argument based in quantum field theory. Also, and most impo...

  13. Modeling energy and charge transports in pi-conjugated systems

    Science.gov (United States)

    Shin, Yongwoo

    Carbon based pi-conjugated materials, such as conducting polymers, fullerene, carbon nanotubes, graphene, and conjugated dendrimers have attracted wide scientific attentions in the past three decades. This work presents the first unified model Hamiltonian that can accurately capture the low-energy excitations among all these pi-conjugated systems, even with the presence of defects and heterogeneous sites. Two transferable physical parameters are incorporated into the Su-Schrieffer-Heeger Hamiltonian to model conducting polymers beyond polyacetylene: the parameter gamma scales the electronphonon coupling strength in aromatic rings and the other parameter epsilon specifies the heterogeneous core charges. This generic Hamiltonian predicts the fundamental band gaps of polythiophene, polypyrrole, polyfuran, poly-(p-phenylene), poly-(p-phenylene vinylene), polyacenes, fullerene, carbon nanotubes, graphene, and graphene nanoribbons with an accuracy exceeding time-dependent density functional theory. Its computational costs for moderate-length polymer chains are more than eight orders of magnitude lower than first-principles approaches. The charge and energy transports along -conjugated backbones can be modeled on the adiabatic potential energy surface. The adiabatic minimum-energy path of a self-trapped topological soliton is computed for trans-polyacetylene. The frequently cited activation barrier via a ridge shift of the hyper-tangent order parameter overestimates its true value by 14 orders of magnitude. Self-trapped solitons migrate along the Goldstone mode direction with continuously adjusted amplitudes so that a small-width soliton expands and a large-width soliton shrinks when they move uphill. A soliton with the critical width may migrate without any amplitude modifications. In an open chain as solitons move from the chain center toward a chain edge, the minimum-energy path first follows a tilted washboard. Such a generic constrained Goldstone mode relaxation

  14. Design principle for increasing charge mobility of π-conjugated polymers using regularly localized molecular orbitals

    OpenAIRE

    Terao, Jun; Wadahama, Akihisa; Matono, Akitoshi; Tada, Tomofumi; Watanabe, Satoshi; Seki, Shu; Fujihara, Tetsuaki; Tsuji, Yasushi

    2013-01-01

    The feasibility of using π-conjugated polymers as next-generation electronic materials is extensively studied; however, their charge mobilities are lower than those of inorganic materials. Here we demonstrate a new design principle for increasing the intramolecular charge mobility of π-conjugated polymers by covering the π-conjugated chain with macrocycles and regularly localizing π-molecular orbitals to realize an ideal orbital alignment for charge hopping. Based on theoretical predictions, ...

  15. Extracting electrode space charge limited current: Charge injection into conjugated polyelectrolytes with a semiconductor electrode

    Science.gov (United States)

    Walker, Ethan M.; Lonergan, Mark C.

    2016-05-01

    Conjugated polyelectrolytes and related mixed ionic-electronic conductors (MIECs) are being explored for energy applications including solid-state lighting and photovoltaics. Fundamental models of charge injection into MIECs have been primarily developed for MIECs contacted with highly conductive or metal electrodes (MEs), despite many potential applications involving semiconductors. We theoretically and experimentally demonstrate that an appropriate semiconductor electrode (SE), n-type for electron or p-type of hole injection, can limit injection into MIECs. When the SE is the injecting electrode and is under accumulation, there is little difference from a ME. When the SE acts as the extracting electrode, however, injection into the MIEC can be limited because a fraction of any applied bias must support charge depletion in the semiconductor rather than charge injection into the MIEC. In a ME/MIEC/SE system, this can lead to significant asymmetry in current-voltage and injected charge-voltage behavior.

  16. Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO3-x) and Titanium (aTiO2-x) Oxide Thin Films

    Science.gov (United States)

    Triana, C. A.; Granqvist, C. G.; Niklasson, G. A.

    2014-11-01

    We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO3-x and aTiO2-x, under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest good optical modulation and charge capacity upon Li+-ion-electron inter/deintercalation for almost stoichiometric films.

  17. Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO3-x) and Titanium (aTiO2-x) Oxide Thin Films

    International Nuclear Information System (INIS)

    We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO3-x and aTiO2-x, under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest good optical modulation and charge capacity upon Li+-ion-electron inter/deintercalation for almost stoichiometric films

  18. How to construct self/anti-self charge conjugate states?

    International Nuclear Information System (INIS)

    We construct self/anti–self charge conjugate (Majorana–like) states for the (1/2, 0)⊕(0, 1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac–like and Majorana–like field operators are considered. The discrete symmetries properties (P, C, T) are studied. The corresponding dynamical equations are presented. In the (1/2, 0) ⊕ (0, 1/2) representation they obey the Dirac–like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The particular attention has been paid to the questions of chirality and helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states. We further review several experimental consequences which follow from the previous works of M. Kirchbach et al. on neutrinoless double beta decay, and G. J. Ni et al. on meson lifetimes

  19. On the non-relativistic limit of charge conjugation in QED

    CERN Document Server

    Perez, B Carballo

    2010-01-01

    We study the non-relativistic limit of the the charge conjugation operation (C) in Quantum Electrodynamics (QED). We arrive to the conclusion that, in the galilean limit, charge conjugation is not a symmetry in the context of QED. Nevertheless, it is possible to find the non-relativistic limit of C, considering the Dirac field coupled to an electromagnetic classical external field. We report the expressions for both the C matrix and the $\\hat{C}$ operator for "slow" electrons and positrons.

  20. Local charge trapping in conjugated polymers resolved by scanning Kelvin probe microscopy

    OpenAIRE

    Hallam, T.; Lee, M.; N. Zhao; Nandhakumar, I; Kemerink, M Martijn; Heeney, M.; McCulloch, I; Sirringhaus, H.

    2009-01-01

    The microstructure of conjugated polymers is heterogeneous on the length scale of individual polymer chains, but little is known about how this affects their electronic properties. Here we use scanning Kelvin probe microscopy with resolution-enhancing carbon nanotube tips to study charge transport on a 100 nm scale in a chain-extended, semicrystalline conjugated polymer. We show that the disordered grain boundaries between crystalline domains constitute preferential charge trapping sites and ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-29

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

  2. The invariance of classical electromagnetism under Charge-conjugation, Parity and Time-reversal (CPT) transformations

    Science.gov (United States)

    Norbury, John W.

    1989-01-01

    The invariance of classical electromagnetism under charge-conjugation, parity, and time-reversal (CPT) is studied by considering the motion of a charged particle in electric and magnetic fields. Upon applying CPT transformations to various physical quantities and noting that the motion still behaves physically demonstrates invariance.

  3. On Charge Conjugation, Chirality and Helicity of the Dirac and Majorana Equation for Massive Leptons

    Directory of Open Access Journals (Sweden)

    Eckart Marsch

    2015-04-01

    Full Text Available We revisit the charge-conjugation operation for the Dirac equation in its chiral representation. A new decomposition of the Dirac spinor field is suggested and achieved by means of projection operators based on charge conjugation, which is discussed here in a non-standard way. Thus, two separate two-component Majorana-type field equations for the eigenfields of the charge-conjugation operator are obtained. The corresponding free fields are entirely separated without a gauge field, but remain mixed and coupled together through an electromagnetic field term. For fermions that are charged and, thus, subjected to the gauge field of electrodynamics, these two Majorana fields can be reassembled into a doublet, which is equivalent to a standard four-component Dirac spinor field. In this way, the Dirac equation is retained in a new guise, which is fully equivalent to that equation in its chiral form.

  4. Crystal Growth of new charge-transfer salts based on $\\pi$-conjugated molecules

    CERN Document Server

    Morherr, Antonia; Chernenkaya, Alisa; Bäcker, Jan-Peter; Schönhense, Gerd; Bolte, Michael; Krellner, Cornelius

    2016-01-01

    New charge transfer crystals of $\\pi$-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure is reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F$_x$, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with $\\pi$-conjug...

  5. Crystal growth of new charge-transfer salts based on π-conjugated donor molecules

    Science.gov (United States)

    Morherr, Antonia; Witt, Sebastian; Chernenkaya, Alisa; Bäcker, Jan-Peter; Schönhense, Gerd; Bolte, Michael; Krellner, Cornelius

    2016-09-01

    New charge transfer crystals of π-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-Fx, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π-conjugated donor molecules.

  6. A general relationship between disorder, aggregation and charge transport in conjugated polymers

    KAUST Repository

    Noriega, Rodrigo

    2013-08-04

    Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials. © 2013 Macmillan Publishers Limited. All rights reserved.

  7. Photogeneration of free charge carriers in tenuously packed .pi. conjugated polymer chains

    Czech Academy of Sciences Publication Activity Database

    Menšík, Miroslav; Pfleger, Jiří; Rybak, A.; Jung, J.; Ulanski, J.; Halašová, Klára; Vohlídal, J.

    2011-01-01

    Roč. 22, č. 12 (2011), s. 2075-2083. ISSN 1042-7147 R&D Projects: GA ČR GA202/07/0643; GA AV ČR KAN100500652; GA AV ČR IAA401770601; GA MŠk 7E10040 Institutional research plan: CEZ:AV0Z40500505 Keywords : photogeneration of free charge carriers * charge transfer states * conjugated polymers Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.007, year: 2011

  8. Temperature dependence of charge transport in conjugated single molecule junctions

    Science.gov (United States)

    Huisman, Eek; Kamenetska, Masha; Venkataraman, Latha

    2011-03-01

    Over the last decade, the break junction technique using a scanning tunneling microscope geometry has proven to be an important tool to understand electron transport through single molecule junctions. Here, we use this technique to probe transport through junctions at temperatures ranging from 5K to 300K. We study three amine-terminated (-NH2) conjugated molecules: a benzene, a biphenyl and a terphenyl derivative. We find that amine groups bind selectively to undercoordinate gold atoms gold all the way down to 5K, yielding single molecule junctions with well-defined conductances. Furthermore, we find that the conductance of a single molecule junction increases with temperature and we present a mechanism for this temperature dependent transport result. Funded by a Rubicon Grant from The Netherlands Organisation for Scientific Research (NWO) and the NSEC program of NSF under grant # CHE-0641523.

  9. Model of the charge carrier mobility in conjugated polymers containing dipolar species

    Czech Academy of Sciences Publication Activity Database

    Toman, Petr; Menšík, Miroslav

    Pisa : European Polymer Federation, 2013. O7-9. [European Polymer Congress - EPF 2013. 16.06.2013-21.06.2013, Pisa] R&D Projects: GA ČR(CZ) GAP205/10/2280 Institutional support: RVO:61389013 Keywords : charge carrier mobility * conjugated polymer * Marcus theory Subject RIV: BM - Solid Matter Physics ; Magnetism

  10. Toward Efficient Orange Emissive Carbon Nanodots through Conjugated sp(2) -Domain Controlling and Surface Charges Engineering.

    Science.gov (United States)

    Qu, Songnan; Zhou, Ding; Li, Di; Ji, Wenyu; Jing, Pengtao; Han, Dong; Liu, Lei; Zeng, Haibo; Shen, Dezhen

    2016-05-01

    A strategy of achieving efficient orange emissive carbon nanodots (CNDs) with large sized conjugated sp(2) -domain is achieved in a solvothermal synthetic route using dimethylformamide as solvent, which is the basis of orange bandgap emission; enhanced orange emission with photoluminescent quantum yield of 46% is realized through surface charges engineering by surface metal-cation-functionalization. PMID:26919550

  11. Two-dimensional charge transport in self-organized, high-mobility conjugated polymers

    DEFF Research Database (Denmark)

    Sirringhaus, H.; Brown, P.J.; Friend, R.H.;

    1999-01-01

    Self-organization in many solution-processed, semiconducting conjugated polymers results in complex microstructures, in which ordered microcrystalline domains are embedded in an amorphous matrix(I). This has important consequences for electrical properties of these materials: charge transport is ...

  12. Charge transfer in conjugated oligomers encapsulated into carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Almadori, Y.; Alvarez, L.; Michel, T.; Le Parc, R.; Bantignies, J.L.; Hermet, P.; Sauvajol, J.L. [Laboratoire Charles Coulomb UMR 5521, Universite Montpellier 2, 34095 Montpellier (France); Laboratoire Charles Coulomb UMR 5521, CNRS, 34095 Montpellier (France); Arenal, R. [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 92322 Chatillon (France); Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, U. Zaragoza, 50018 Zaragoza (Spain); Babaa, R. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France); Chemical Engineering Department, University of Technology PETRONAS, UTP, Ipoh-Perak (Malaysia); Jouselme, B.; Palacin, S. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-15

    This study deals with a hybrid system consisting in quaterthiophene derivative encapsulated inside single-walled and multi-walled carbon nanotubes. Investigations of the encapsulation step are performed by transmission electron microscopy. Raman spectroscopy data point out different behaviors depending on the laser excitation energy with respect to the optical absorption of quaterthiophene. At low excitation energy (far from the oligomer resonance window) there is no significant modification of the Raman spectra before and after encapsulation. By contrast, at high excitation energy (close to the oligomer resonance window), Raman spectra exhibit a G-band shift together with an important RBM intensity loss, suggesting a significant charge transfer between the inserted molecule and the host nanotubes. Those results suggest a photo induced process leading to a significant charge transfer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Enhancing charge storage of conjugated polymer electrodes with phenolic acids

    Science.gov (United States)

    Wagner, Michal; Rębiś, Tomasz; Inganäs, Olle

    2016-01-01

    We here present studies of electrochemical doping of poly(1-aminoanthraquinone) (PAAQ) films with three structurally different phenolic acids. The examined phenolic acids (sinapic, ferulic and syringic acid) were selected due to their resemblance to redox active groups, which can be found in lignin. The outstanding electrochemical stability of PAAQ films synthesized for this work enabled extensive cycling of phenolic acid-doped PAAQ films. Potentiodynamic and charge-discharge studies revealed that phenolic acid-doped PAAQ films exhibited enhanced capacitance in comparison to undoped PAAQ films, together with appearance of redox activity characteristics specific for each dopant. Electrochemical kinetic studies performed on microelectrodes affirmed the fast electron transfer for hydroquinone-to-quinone reactions with these phenolic compounds. These results imply the potential application of phenolic acids in cheap and degradable energy storage devices.

  14. Multi-triphenylamine-substituted porphyrin-fullerene conjugates as charge stabilizing "antenna-reaction center" mimics.

    Science.gov (United States)

    D'Souza, Francis; Gadde, Suresh; Islam, D-M Shafiqul; Wijesinghe, Channa A; Schumacher, Amy L; Zandler, Melvin E; Araki, Yasuyaki; Ito, Osamu

    2007-09-01

    A new concept of charge stabilization via delocalization of the pi-cation radical species over the donor macrocycle substituents in a relatively simple donor-acceptor bearing multimodular conjugates is reported. The newly synthesized multimodular systems were composed of three covalently linked triphenylamine entities at the meso position of the porphyrin ring and one fulleropyrrolidine at the fourth meso position. The triphenylamine entities were expected to act as energy transferring antenna units and to enhance the electron donating ability of both free-base and zinc(II) porphyrin derivatives of these pentads. Appreciable electronic interactions between the meso-substituted triphenylamine entities and the porphyrin pi-system were observed, and as a consequence, these moieties acted together as an electron-donor while the fullerene moiety acted as an electron-acceptor in the multimodular conjugates. In agreement with the spectral and electrochemical results, the computational studies performed by the DFT B3LYP/3-21G(*) method revealed delocalization of the frontier highest occupied molecular orbital (HOMO) over the triphenylamine entities in addition to the porphyrin macrocycle. Free-energy calculations suggested that the light-induced processes from the singlet excited state of porphyrins are exothermic in the investigated multimodular conjugates. The occurrence of photoinduced charge-separation and charge-recombination processes was confirmed by the combination of time-resolved fluorescence and nanosecond transient absorption spectral measurements. Charge-separated states, on the order of a few microseconds, were observed as a result of the delocalization of the pi-cation radical species over the porphyrin macrocycle and the meso-substituted triphenylamine entities. The present study successfully demonstrates a novel approach of charge-stabilization in donor-acceptor multimodular conjugates. PMID:17608464

  15. Impact of charge carrier injection on single-chain photophysics of conjugated polymers

    CERN Document Server

    Hofmann, Felix J; Lupton, John M

    2016-01-01

    Charges in conjugated polymer materials have a strong impact on the photophysics and their interaction with the primary excited state species has to be taken into account in understanding device properties. Here, we employ single-molecule spectroscopy to unravel the influence of charges on several photoluminescence (PL) observables. The charges are injected either stochastically by a photochemical process, or deterministically in a hole-injection sandwich device configuration. We find that upon charge injection, besides a blue-shift of the PL emission and a shortening of the PL lifetime due to quenching and blocking of the lowest-energy chromophores, the non-classical photon arrival time distribution of the multichromophoric chain is modified towards a more classical distribution. Surprisingly, the fidelity of photon antibunching deteriorates upon charging, whereas one would actually expect the number of chromophores to be reduced. A qualitative model is presented to explain the observed PL changes. The resul...

  16. Self/Anti-Self Charge Conjugate States for $j=1/2$ and $j=1$

    CERN Document Server

    Dvoeglazov, V V

    1997-01-01

    We briefly review recent achievements in the theory of neutral particles (the Majorana-McLennan-Case-Ahluwalia construct for self/anti-self charge conjugate states for j=1/2 and j=1 cases). Among new results we present a theoretical construct in which a fermion and an antifermion have the same intrinsic parity; discuss phase transformations and find relations between the Majorana-like field operator $\

  17. Epitaxial thin films of ATiO(3-x)H(x) (A = Ba, Sr, Ca) with metallic conductivity.

    Science.gov (United States)

    Yajima, Takeshi; Kitada, Atsushi; Kobayashi, Yoji; Sakaguchi, Tatsunori; Bouilly, Guillaume; Kasahara, Shigeru; Terashima, Takahito; Takano, Mikio; Kageyama, Hiroshi

    2012-05-30

    Epitaxial thin films of titanium perovskite oxyhydride ATiO(3-x)H(x) (A = Ba, Sr, Ca) were prepared by CaH(2) reduction of epitaxial ATiO(3) thin films deposited on a (LaAlO(3))(0.3)(SrAl(0.5)Ta(0.5)O(3))(0.7) substrate. Secondary ion mass spectroscopy detected a substantial amount and uniform distribution of hydride within the film. SrTiO(3)/LSAT thin film hydridized at 530 °C for 1 day had hydride concentration of 4.0 × 10(21) atoms/cm(3) (i.e., SrTiO(2.75)H(0.25)). The electric resistivity of all the ATiO(3-x)H(x) films exhibited metallic (positive) temperature dependence, as opposed to negative as in BaTiO(3-x)H(x) powder, revealing that ATiO(3-x)H(x) are intrinsically metallic, with high conductivity of 10(2)-10(4) S/cm. Treatment with D(2) gas results in hydride/deuteride exchange of the films; these films should be valuable in further studies on hydride diffusion kinetics. Combined with the materials' inherent high electronic conductivity, new mixed electron/hydride ion conductors may also be possible. PMID:22563869

  18. Impact of charge carrier injection on single-chain photophysics of conjugated polymers

    Science.gov (United States)

    Hofmann, Felix J.; Vogelsang, Jan; Lupton, John M.

    2016-06-01

    Charges in conjugated polymer materials have a strong impact on the photophysics and their interaction with the primary excited state species has to be taken into account in understanding device properties. Here, we employ single-molecule spectroscopy to unravel the influence of charges on several photoluminescence (PL) observables. The charges are injected either stochastically by a photochemical process or deterministically in a hole-injection sandwich device configuration. We find that upon charge injection, besides a blue-shift of the PL emission and a shortening of the PL lifetime due to quenching and blocking of the lowest-energy chromophores, the non-classical photon arrival time distribution of the multichromophoric chain is modified towards a more classical distribution. Surprisingly, the fidelity of photon antibunching deteriorates upon charging, whereas one would actually expect the opposite: the number of chromophores to be reduced. A qualitative model is presented to explain the observed PL changes. The results are of interest to developing a microscopic understanding of the intrinsic charge-exciton quenching interaction in devices.

  19. Charged free fermions, vertex operators and the classical theory of conjugate nets

    Energy Technology Data Exchange (ETDEWEB)

    Doliwa, Adam [Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Rome (Italy); Instytut Fizyki Teoretycznej, Uniwersytet Warszawski, Warsaw (Poland); Manas, Manuel [Departamento de Matematica Aplicada y Estadistica, EUIT Aeronautica, Universidad Politecnica de Madrid, Madrid (Spain); Departamento de Fisica Teorica, Universidad Complutense, Madrid (Spain); Martinez Alonso, Luis; Medina, Elena [Departamento de Matematicas, Universidad de Cadiz, Cadiz (Spain); Santini, Paolo Maria [Istituto Nazionale di Fisica Nucleare, Sezione di Roma, Rome (Italy); Dipartimento di Fisica, Universita di Catania, Catania (Italy)

    1999-02-19

    We show that the quantum field theoretical formulation of the {tau}-function theory has a geometrical interpretation within the classical transformation theory of conjugate nets. In particular, we prove that (i) the partial charge transformations preserving the neutral sector are Laplace transformations, (ii) the basic vertex operators are Levy and adjoint Levy transformations and (iii) the diagonal soliton vertex operators generate fundamental transformations. We also show that the bilinear identity for the multicomponent Kadomtsev-Petviashvili hierarchy becomes, through a generalized Miwa map, a bilinear identity for the multidimensional quadrilateral lattice equations. (author)

  20. Charged free fermions, vertex operators and the classical theory of conjugate nets

    International Nuclear Information System (INIS)

    We show that the quantum field theoretical formulation of the τ-function theory has a geometrical interpretation within the classical transformation theory of conjugate nets. In particular, we prove that (i) the partial charge transformations preserving the neutral sector are Laplace transformations, (ii) the basic vertex operators are Levy and adjoint Levy transformations and (iii) the diagonal soliton vertex operators generate fundamental transformations. We also show that the bilinear identity for the multicomponent Kadomtsev-Petviashvili hierarchy becomes, through a generalized Miwa map, a bilinear identity for the multidimensional quadrilateral lattice equations. (author)

  1. Controlled Charge Trapping and Retention in Large-Area Monodisperse Protein Metal-Nanoparticle Conjugates.

    Science.gov (United States)

    Kim, Chang-Hyun; Bhak, Ghibom; Lee, Junghee; Sung, Sujin; Park, Sungjun; Paik, Seung R; Yoon, Myung-Han

    2016-05-18

    Here, we report on charge-retention transistors based on novel protein-mediated Au nanoparticle (NP) arrays, with precise control over dimension and distribution. Individual NPs are coated with alpha-synuclein, an amyloidogenic protein responsible for Lewy body formation in Parkinson's disease. Subsequently, a monolayer of protein-NP conjugates is successfully created via a simple and scalable solution deposition to function as distributed nanoscale capacitors. Controllability over the film structure translates into the tunability of the electrical performance; pentacene-based organic transistors feature widely varying programmability and relaxation dynamics, providing versatility for various unconventional memory applications. PMID:27144458

  2. Self/anti-self charge conjugate states in the helicity basis

    Energy Technology Data Exchange (ETDEWEB)

    Dvoeglazov, Valeriy V. [UAF, Universidad de Zacatecas (Mexico)

    2013-07-23

    We construct self/anti-self charge conjugate (Majorana-like) states for the (1/2,0)⊕(0,1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac-like and Majorana-like field operators are considered. The discrete symmetries properties (P, C, T) are studied. Particular attention has been paid to the question of (anti)commutation of the Charge conjugation operator and the Parity in the helicity basis. Dynamical equations have also been presented. In the (1/2,0)⊕(0,1/2) representation they obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The chirality and the helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states have been discussed.

  3. Glass transition dynamics and charge carrier mobility in conjugated polyfluorene thin films

    Science.gov (United States)

    Qin, Hui; Liu, Dan; Wang, Tao

    Conjugated polymers are commonly used in organic optoelectronic devices, e.g. organic photovoltaics (OPVs), light-emitting diodes (LEDs) and field effect transistors (FETs). In these devices, the conjugated polymers are prepared as thin films with thicknesses in the range of tens to hundreds of nanometers, and are interfaced with different function layers made from organic or inorganic materials. We have studied the glass transition temperature (Tg) of poly(9, 9-dioctylfluorene)-co-N-(1, 4-butylphenyl)diphenylamine) (TFB) thin films supported on different substrates, as well as their SCLC charge carrier mobility in photodiodes. Both Monotonic and non-monotonic Tg deviations are observed in TFB thin films supported on Si/SiOx and PEDOT:PSS, respectively. With low to moderate thermal crosslinking, the thickness dependent Tg deviation still exists, which diminishes in TFB films with a high crosslinking degree. The vertical charge carrier mobility of TFB thin films extracted from the SCLC measurements is found increase with film thickness, a value increases from 1 to 50 x 10-6 cm2 V-1 s-1 in the thickness range from 15 to 180 nm. Crosslinking was found to reduce the carrier mobility in TFB thin films. The Tg deviations are also discussed using the classic layered models in the literature. Our results provide a precise guide for the fabrication and design of high performance optoelectronic devices.

  4. Self/anti-self charge conjugate states in the helicity basis

    International Nuclear Information System (INIS)

    We construct self/anti-self charge conjugate (Majorana-like) states for the (1/2,0)⊕(0,1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac-like and Majorana-like field operators are considered. The discrete symmetries properties (P, C, T) are studied. Particular attention has been paid to the question of (anti)commutation of the Charge conjugation operator and the Parity in the helicity basis. Dynamical equations have also been presented. In the (1/2,0)⊕(0,1/2) representation they obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The chirality and the helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states have been discussed

  5. Efficient photoinduced charge transfer in TiO{sub 2} nanorod/conjugated polymer hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y-T; Zeng, T-W; Lai, W-Z; Chen, C-W; Lin, Y-Y; Chang, Y-S; Su, W-F [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China)

    2006-12-14

    The mechanisms of photoinduced charge transfer in composites of TiO{sub 2} nanorods with a conjugated polymer (poly(2-methoxy-5-(2'-ethyl)(hexyloxy) 1,4-phenylenevinylene) (MEH-PPV) have been investigated by steady-state, time-resolved photoluminescence (PL) spectroscopy and photoluminescence excitation (PLE) spectroscopy. Efficient charge separation takes place at the TiO{sub 2}-nanorod/polymer interfaces when the polymer is excited, leading to quenching of the photoluminescence efficiency {eta} and shortening of the measured lifetime {tau}{sub PL}. In addition, the low-temperature absorption and photoluminescence spectra show that the inclusion of TiO{sub 2} nanorods in polymer can reduce disorder in conformation and enhance conjugation in the polymer chain. A photovoltaic solar cell device based on the MEH-PPV/TiO{sub 2}-nanorod composite material is also presented, which shows a two order increase in short-circuit current J{sub SC} compared to that based on the pristine MEH-PPV.

  6. Role of redox centre in charge transport investigated by novel self-assembled conjugated polymer molecular junctions

    Science.gov (United States)

    Wang, Zongrui; Dong, Huanli; Li, Tao; Hviid, Rune; Zou, Ye; Wei, Zhongming; Fu, Xiaolong; Wang, Erjing; Zhen, Yonggang; Nørgaard, Kasper; Laursen, Bo W.; Hu, Wenping

    2015-06-01

    Molecular electronics describes a field that seeks to implement electronic components made of molecular building blocks. To date, few studies have used conjugated polymers in molecular junctions despite the fact that they potentially transport charge more efficiently than the extensively investigated small-molecular systems. Here we report a novel type of molecular tunnelling junction exploring the use of conjugated polymers, which are self-assembled into ultrathin films in a distinguishable `planar' manner from the traditional vertically oriented small-molecule monolayers. Electrical measurements on the junctions reveal molecular-specific characteristics of the polymeric molecules in comparison with less conjugated small molecules. More significantly, we decorate redox-active functionality into polymeric backbones, demonstrating a key role of redox centre in the modulation of charge transport behaviour via energy level engineering and external stimuli, and implying the potential of employing tailor-made polymeric components as alternatives to small molecules for future molecular-scale electronics.

  7. Charge Transport and Transfer at the Nanoscale Between Metals and Novel Conjugated Materials

    Science.gov (United States)

    Worne, Jeffrey Howard

    Organic semiconductors (OSCs) and graphene are two classes of conjugated materials that hold promise to create flexible electronic displays, high speed transistors, and low-cost solar cells. Crucial to understanding the behavior of these materials is understanding the effects metallic contacts have on the local charge environment. Additionally, characterizing the charge carrier transport behavior within these materials sheds light on the physical mechanisms behind transport. The first part of this thesis examines the origin of the low-temperature, high electric field transport behavior of OSCs. Two chemically distinct OSCs are used, poly-3(hexylthiophene) (P3HT) and 6,13-bis(triisopropyl-silylethynyl) (TIPS) pentacene. Several models explaining the low-temperature behavior are presented, with one using the Tomonaga-Luttinger liquid (TLL) insulator-to-metal transition model and one using a field-emission hopping model. While the TLL model is only valid for 1-dimensional systems, it is shown to work for both P3HT (1D) and TIPS-pentacene (2D), suggesting the TLL model is not an appropriate description of these systems. Instead, a cross-over from thermally-activated hopping to field-emission hopping is shown to explain the data well. The second part of this thesis focuses on the interaction between gold and platinum contacts and graphene using suspended graphene over sub-100 nanometer channels. Contacts to graphene can strongly dominate charge transport and mobility as well as significantly modify the charge environment local to the contacts. Platinum electrodes are discovered to be strong dopants to graphene at short length scales while gold electrodes do not have the same effect. By increasing the separation distance between the electrodes, this discrepancy is shown to disappear, suggesting an upper limit on charge diffusion from the contacts. Finally, this thesis will discuss a novel technique to observe the high-frequency behavior in OSCs using two microwave

  8. How to construct self/anti-self charge conjugate states for higher spins?

    CERN Document Server

    Dvoeglazov, Valeriy V

    2012-01-01

    We construct self/anti-self charge conjugate (Majorana-like) states for the (1/2, 0)+(0, 1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac-like and Majorana-like field operators are considered. The discrete symmetries properties (P, C, T) are studied. The corresponding dynamical equations are presented. In the (1/2, 0)+(0, 1/2) representation they obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The particular attention has been paid to the questions of chirality and helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states. We further review several experimental consequences which follow from the previous works of M.Kirchbach et al. on neutrinoless double beta decay, and G.J.Ni et al. on meson ...

  9. Theoretical estimation of the rate of photoinduced charge transfer reactions in triphenylamine C60 donor-acceptor conjugate.

    Science.gov (United States)

    Martínez, Juan Pablo; Solà, Miquel; Voityuk, Alexander A

    2016-06-01

    Fullerene-based molecular heterojunctions such as the [6,6]-pyrrolidine-C60 donor-acceptor conjugate containing triphenylamine (TPA) are potential materials for high-efficient dye-sensitized solar cells. In this work, we estimate the rate constants for the photoinduced charge separation and charge recombination processes in TPA-C60 using the unrestricted and time-dependent DFT methods. Different schemes are applied to evaluate excited state properties and electron transfer parameters (reorganization energies, electronic couplings, and Gibbs energies). The use of open-shell singlet or triplet states, several density functionals, and continuum solvation models is discussed. Strengths and limitations of the computational approaches are highlighted. The present benchmark study provides an overview of the expected performance of DFT-based methodologies in the description of photoinduced charge transfer reactions in fullerene heterojunctions. © 2016 Wiley Periodicals, Inc. PMID:26992355

  10. Electrochromic Properties of Li+-Intercalated Amorphous Tungsten (aWO(3-x)) and Titanium (aTiO(2-x)) Oxide Thin Films

    OpenAIRE

    Triana, Carlos A.; Granqvist, Claes-Göran; Niklasson, Gunnar

    2014-01-01

    We report on electrochromic properties of stoichiometric and oxygen-deficient amorphous films, denoted aWO(3-x) and aTiO(2-x), under Li+-ion-electron inter/deintercalation. Optical characterization of the films in their as-deposited, fully intercalated (dark), and bleached states were performed by in-situ optical transmittance measurements. We explore electrochromism and optical absorption phenomena in the context of oxygen deficiency and nanostructure. Studies by cyclic voltammetry suggest g...

  11. Electroluminescence and charge photogeneration in .pi. and .sigma.-conjugated polymers and their blends

    Czech Academy of Sciences Publication Activity Database

    Cimrová, Věra; Výprachtický, Drahomír; Hlídková, Helena; Pavlačková, Petra; Kukla, Stanislav

    Dresden : Max Planck Institute for the Physic of Complex Systems, 2005. [MPG-MOEL– Symposium: Science and Art in Europe, Polymers: Materials in Nature and in Advanced Technologies. 23.5.2005-25.5.2005, Dresden] R&D Projects: GA AV ČR(CZ) IAA4050409; GA ČR(CZ) GA203/04/1372 Keywords : electroluminescence * conjugated polymers Subject RIV: CD - Macromolecular Chemistry

  12. Charge Transport in 4 nm Molecular Wires with Interrupted Conjugation: Combined Experimental and Computational Evidence for Thermally Assisted Polaron Tunneling.

    Science.gov (United States)

    Taherinia, Davood; Smith, Christopher E; Ghosh, Soumen; Odoh, Samuel O; Balhorn, Luke; Gagliardi, Laura; Cramer, Christopher J; Frisbie, C Daniel

    2016-04-26

    We report the synthesis, transport measurements, and electronic structure of conjugation-broken oligophenyleneimine (CB-OPI 6) molecular wires with lengths of ∼4 nm. The wires were grown from Au surfaces using stepwise aryl imine condensation reactions between 1,4-diaminobenzene and terephthalaldehyde (1,4-benzenedicarbaldehyde). Saturated spacers (conjugation breakers) were introduced into the molecular backbone by replacing the aromatic diamine with trans-1,4-diaminocyclohexane at specific steps during the growth processes. FT-IR and ellipsometry were used to follow the imination reactions on Au surfaces. Surface coverages (∼4 molecules/nm(2)) and electronic structures of the wires were determined by cyclic voltammetry and UV-vis spectroscopy, respectively. The current-voltage (I-V) characteristics of the wires were acquired using conducting probe atomic force microscopy (CP-AFM) in which an Au-coated AFM probe was brought into contact with the wires to form metal-molecule-metal junctions with contact areas of ∼50 nm(2). The low bias resistance increased with the number of saturated spacers, but was not sensitive to the position of the spacer within the wire. Temperature dependent measurements of resistance were consistent with a localized charge (polaron) hopping mechanism in all of the wires. Activation energies were in the range of 0.18-0.26 eV (4.2-6.0 kcal/mol) with the highest belonging to the fully conjugated OPI 6 wire and the lowest to the CB3,5-OPI 6 wire (the wire with two saturated spacers). For the two other wires with a single conjugation breaker, CB3-OPI 6 and CB5-OPI 6, activation energies of 0.20 eV (4.6 kcal/mol) and 0.21 eV (4.8 kcal/mol) were found, respectively. Computational studies using density functional theory confirmed the polaronic nature of charge carriers but predicted that the semiclassical activation energy of hopping should be higher for CB-OPI molecular wires than for the OPI 6 wire. To reconcile the experimental and

  13. Controlled Growth of Well-Defined Conjugated Polymers from the Surfaces of Multiwalled Carbon Nanotubes: Photoresponse Enhancement via Charge Separation.

    Science.gov (United States)

    Hou, Wenpeng; Zhao, Ning-Jiu; Meng, Dongli; Tang, Jing; Zeng, Yi; Wu, Yu; Weng, Yangziwan; Cheng, Chungui; Xu, Xiulai; Li, Yi; Zhang, Jian-Ping; Huang, Yong; Bielawski, Christopher W; Geng, Jianxin

    2016-05-24

    The installation of heterojunctions on the surfaces of carbon nanotubes (CNTs) is an effective method for promoting the charge separation processes needed for CNT-based electronics and optoelectronics applications. Conjugated polymers are proven state-of-the-art candidates for modifying the surfaces of CNTs. However, all previous attempts to incorporate conjugated polymers to CNTs resulted in unordered interfaces. Herein we show that well-defined chains of regioregular poly(3-hexylthiophene) (P3HT) were successfully grown from the surfaces of multiwalled CNTs (MWNTs) using surface-initiated Kumada catalyst-transfer polycondensation. The polymerization was found to proceed in a controlled manner as chains of tunable lengths were prepared through variation of the initial monomer-to-initiator ratio. Moreover, it was determined that large-diameter MWNTs afforded highly ordered P3HT aggregates, which exhibited a markedly bathochromically shifted optical absorption due to a high grafting density induced planarization of the polymer chains. Using ultrafast spectroscopy, the heterojunctions formed between the MWNTs and P3HT were shown to effectively overcome the binding energy of excitons, leading to photoinduced electron transfer from P3HT to MWNTs. Finally, when used as prototype devices, the individual MWNT-g-P3HT core-shell structures exhibited excellent photoresponses under a low illumination density. PMID:27087146

  14. Engineering the unitary charge conjugation operator of quantum field theory for particle–antiparticle using trapped ions and light fields in cavity QED

    International Nuclear Information System (INIS)

    In this paper we present a method to engineer the unitary charge conjugation operator, as given by quantum field theory, in the highly controlled context of quantum optics, thus allowing one to simulate the creation of charged particles with well-defined momenta simultaneously with their respective antiparticles. Our method relies on trapped ions driven by a laser field and interacting with a single mode of a light field in a high Q cavity. (paper)

  15. Thiophene fused azacoronenes: regioselective synthesis, self organization, charge transport, and its incorporation in conjugated polymers

    Science.gov (United States)

    Liu, Yi; He, Bo

    2015-09-15

    A regioselective synthesis of an azacoronene fused with two peripheral thiophene groups has been realized through a concise synthetic route. The resulting thienoazacoronene (TAC) derivatives show high degree of self-organization in solution, in single crystals, in the bulk, and in spuncast thin films. Spuncast thin film field-effect transistors of the TACs exhibited mobilities up to 0.028 cm.sup.2V.sup.-1 S.sup.-1, which is among the top field effect mobilities for solution processed discotic materials. Organic photovoltaic devices using TAC-containing conjugated polymers as the donor material exhibited a high open-circuit voltage of 0.89 V, which was ascribable to TAC's low-lying highest occupied molecular orbital energy level.

  16. Effect of traps on the transport of charge carriers in single chains of conjugated polymers and in their macroscopic ensembles. A kinetic approach

    Czech Academy of Sciences Publication Activity Database

    Sworakowski, J.; Nešpůrek, Stanislav

    Sao Paulo : University of Sao Paulo, 2005, s. 360-363. ISBN 0-7803-9116-0. [International Symposium on Electrets /12./. Salvador (BR), 11.09.2005-14.09.2005] Institutional research plan: CEZ:AV0Z40500505 Keywords : charge transport * traps * conjugated polymer Subject RIV: CD - Macromolecular Chemistry

  17. Entanglements in Marginal Solutions: A Means of Tuning Pre-Aggregation of Conjugated Polymers with Positive Implications for Charge Transport

    KAUST Repository

    Hu, Hanlin

    2015-06-17

    The solution-processing of conjugated polymers, just like commodity polymers, is subject to solvent and molecular weight-dependent solubility, interactions and chain entanglements within the polymer, all of which can influence the crystallization and microstructure development in semi-crystalline polymers and consequently affect charge transport and optoelectronic properties. Disentanglement of polymer chains in marginal solvents was reported to work via ultrasonication, facilitating the formation of photophysically ordered polymer aggregates. In this contribution, we explore how a wide range of technologically relevant solvents and formulations commonly used in organic electronics influence chain entanglement and the aggregation behaviour of P3HT using a combination of rheological and spectrophotometric measurements. The specific viscosity of the solution offers an excellent indication of the degree of entanglements in the solution, which is found to be related to the solubility of P3HT in a given solvent. Moreover, deliberately disentangling the solution in the presence of solvophobic driving forces, leads consistently to formation of photophysically visible aggregates which is indicative of local and perhaps long range order in the solute. We show for a broad range of solvents and molecular weights that disentanglement ultimately leads to significant ordering of the polymer in the solid state and a commensurate increase in charge transport properties. In doing so we demonstrate a remarkable ability to tune the microstructure which has important implications for transport properties. We discuss its potential implications in the context of organic photovoltaics.

  18. Photogeneration of free charge carriers in .pi.-conjugated polymers with bulky side groups

    Czech Academy of Sciences Publication Activity Database

    Menšík, Miroslav; Jex, M.; Pfleger, Jiří; Jung, J.

    Vilnius: Center for Physical Sciences and Technology, 2011. s. 124. ISBN 978-9955-634-36-2. [International Conference "Electronic and Related Properties of Organic Systems" /12./ - ERPOS-12. 11.07.2011-13.07.2011, Vilnius] R&D Projects: GA MŠk(CZ) OC10007; GA MŠk MEB051010; GA ČR(CZ) GAP205/10/2280 Institutional research plan: CEZ:AV0Z40500505 Keywords : charge carrier transport * polymer Subject RIV: BM - Solid Matter Physics ; Magnetism

  19. Inter-chain charge carrier mobility in conjugated polymers doped with polar additives

    Czech Academy of Sciences Publication Activity Database

    Toman, Petr

    Prague : CESNET, 2010 - (Křenková, I.; Antoš, D.; Matyska, L.), s. 137-143 ISBN 978-80-904173-7-3 R&D Projects: GA ČR GA203/06/0285; GA AV ČR IAA401770601; GA MŠk MEB050815 Institutional research plan: CEZ:AV0Z40500505 Keywords : charge carrier mobility * switching * Marcus theory Subject RIV: CF - Physical ; Theoretical Chemistry https://www.metacentrum.cz/export/ sites /metacentrum/cs/about/results/yearbooks/MetaCentrum_Yearbook9_web.pdf

  20. Test of charge conjugation invariance in eta->pi0 e+e- and eta->pi+pi-pi0 decays

    CERN Document Server

    Zielinski, M

    2013-01-01

    Charge conjugation C is one of the fundamental symmetries in nature which transforms particles into antiparticles. This symmetry was studied in weak interaction where it is fully violated, but it is poorly known in the strong and electromagnetic interactions. To this end, in this thesis we investigated eta->pi+pi-pi0 and eta->pi0 e+e- decays, which might violate charge conjugation symmetry. The violation of C symmetry in eta->pi+pi-pi0 process could manifest itself as an asymmetry between energy spectra of charged pions. The eta->pi0 e+e- decay is forbidden by C symmetry in the first order of electromagnetic interaction, with the branching ratio on a level of 10^-8. Therefore, observation of a larger branching ratio could indicate a mechanism involving first order electromagnetic interaction violating charge conjugation. Both decays were investigated by means of the WASA-at-COSY detector operating at the COSY synchrotron at the Forchungszentrum Julich in Germany. The eta meson was produced via pp->pp eta reac...

  1. Use of a charge reducing agent to enable intact mass analysis of cysteine-linked antibody-drug-conjugates by native mass spectrometry

    Directory of Open Access Journals (Sweden)

    Kamila J. Pacholarz

    2016-06-01

    Full Text Available Antibody-drug-conjugates (ADC are a growing class of anticancer biopharmaceuticals. Conjugation of cysteine linked ADCs, requires initial reduction of mAb inter-chain disulfide bonds, as the drugs are attached via thiol chemistry. This results in the active mAb moiety being transformed from a covalently linked tetramer to non-covalently linked complexes, which hinders precise determination of drug load with LC–MS. Here, we show how the addition of the charge reducing agent triethylammonium acetate (TEAA preserves the intact mAb structure, is well suited to the study of cysteine linked conjugates and facilitates easy drug load determination by direct infusion native MS.

  2. New example of charge conjugation and parity violation from search for a permanent electric dipole moment of Rubidium atom

    CERN Document Server

    You, Pei-Lin

    2008-01-01

    Quantum mechanics thinks that all atoms do not have permanent electric dipole moment (EDM) because of their spherical symmetry. Therefore, there is no polar atom in nature except for polar molecules. The electric susceptibility Xe caused by the orientation of polar substances is inversely proportional to the absolute temperature T while the induced susceptibility of atoms is temperature independent. Using special capacitors our experiments discovered that directional motion of Rb atoms in a non-uniform electric field and ground state Rb atom is polar atom with a large EDM: d(Rb) =2.72*10-29C.m = 1.70*10-8e.cm. The experiment showed that the relationship between Xe of Rb vapor and T is just Xe =B/T, where the slope B =380(k) as polar molecules. Its capacitance C at different voltage V was measured. The C-V curve shows that the saturation polarization of Rb vapor has be observed when E more than 8.5*104V/m. New example of CP (charge conjugation and parity) violation occurred in Rb atoms (see arXiv 0809.4767). I...

  3. Roughening Conjugated Polymer Surface for Enhancing the Charge Collection Efficiency of Sequentially Deposited Polymer/Fullerene Photovoltaics

    Directory of Open Access Journals (Sweden)

    Yoonhee Jang

    2015-08-01

    Full Text Available A method that enables the formation of a rough nano-scale surface for conjugated polymers is developed through the utilization of a polymer chain ordering agent (OA. 1-Chloronaphthalene (1-CN is used as the OA for the poly(3-hexylthiophene-2,5-diyl (P3HT layer. The addition of 1-CN to the P3HT solution improves the chain ordering of the P3HT during the film formation process and increases the surface roughness of the P3HT film compared to the film prepared without 1-CN. The roughened surface of the P3HT film is utilized to construct a P3HT/fullerene bilayer organic photovoltaic (OPV by sequential solution deposition (SqSD without thermal annealing process. The power conversion efficiency (PCE of the SqSD-processed OPV utilizing roughened P3HT layer is 25% higher than that utilizing a plain P3HT layer. It is revealed that the roughened surface of the P3HT increases the heterojunction area at the P3HT/fullerene interface and this resulted in improved internal charge collection efficiency, as well as light absorption efficiency. This method proposes a novel way to improve the PCE of the SqSD-processed OPV, which can be applied for OPV utilizing low band gap polymers. In addition, this method allows for the reassessment of polymers, which have shown insufficient performance in the BSD process.

  4. Relating pseudospin and spin symmetries through charge conjugation and chiral transformations: The case of the relativistic harmonic oscillator

    International Nuclear Information System (INIS)

    We solve the generalized relativistic harmonic oscillator in 1+1 dimensions, i.e., including a linear pseudoscalar potential and quadratic scalar and vector potentials which have equal or opposite signs. We consider positive and negative quadratic potentials and discuss in detail their bound-state solutions for fermions and antifermions. The main features of these bound states are the same as the ones of the generalized three-dimensional relativistic harmonic oscillator bound states. The solutions found for zero pseudoscalar potential are related to the spin and pseudospin symmetry of the Dirac equation in 3+1 dimensions. We show how the charge conjugation and γ5 chiral transformations relate the several spectra obtained and find that for massless particles the spin and pseudospin symmetry-related problems have the same spectrum but different spinor solutions. Finally, we establish a relation of the solutions found with single-particle states of nuclei described by relativistic mean-field theories with scalar, vector, and isoscalar tensor interactions and discuss the conditions in which one may have both nucleon and antinucleon bound states

  5. Aggregation-induced emission of diarylamino-π-carborane triads: effects of charge transfer and π-conjugation.

    Science.gov (United States)

    Cho, Yang-Jin; Kim, So-Yoen; Cho, Minji; Han, Won-Sik; Son, Ho-Jin; Cho, Dae Won; Kang, Sang Ook

    2016-04-14

    Carborane-based donor-π-acceptor triads (D-π-A-π-D) bearing triarylamine moieties were synthesised. All the monomeric triads showed a blue-green emission in a dilute solution, which was assigned as an intramolecular charge-transfer (CT) emission. The intramolecular CT emission showed large Stokes shifts at a higher solvent polarity. The intramolecular CT emission further shifted to a longer wavelength with the increase in π-conjugation. Interestingly, a strong red emission was observed in highly concentrated solutions or in the solid state, which was assigned as an aggregation-induced emission (AIE). Moreover, the AIE strongly depended on solvent polarity. A large Stokes shift in AIE was attributed to the strong CT character. The changes in the dipole moment for the AIE state and monomer emission were evaluated using the Lippert-Mataga relationship. The density functional theory calculations showed that the change in electron distribution between the aryl amino group (highest occupied molecular orbital, HOMO) and the carborane moiety (lowest unoccupied molecular orbital, LUMO) indicates the intramolecular CT character, and the emission colour changes were attributed to the HOMO-LUMO energy gap controlled by the π-extension of the phenylene linker. The electrochemical properties such as oxidation and reduction potentials were consistent with theoretical calculation results. The emission properties were affected by two main factors: solvent polarity and solubility. PMID:26996491

  6. Light-induced electron paramagnetic resonance evidence of charge transfer in electrospun fibers containing conjugated polymer/fullerene and conjugated polymer/fullerene/carbon nanotube blends

    Energy Technology Data Exchange (ETDEWEB)

    Shames, Alexander I. [Department of Physics, Ben-Gurion University of the Negev, Beersheba 84105 (Israel); Bounioux, Celine [Department of Solar Energy and Environmental Physics, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus 84990 (Israel); Katz, Eugene A. [Department of Solar Energy and Environmental Physics, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus 84990 (Israel); Ilze Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Yerushalmi-Rozen, Rachel [Ilze Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Zussman, Eyal [Department of Mechanical Engineering, Technion, Haifa 32000 (Israel)

    2012-03-12

    Electrospun sub-micron fibers containing conjugated polymer (poly(3-hexylthiophene), P3HT) with a fullerene derivative, phenyl-C61-butyric acid methylester (PCBM) or a mixture of PCBM and single-walled carbon nanotubes (SWCNTs) were studied by light-induced electron paramagnetic resonance spectroscopy. The results provide experimental evidence of electron transfer between PCBM and P3HT components in both fiber systems and suggest that the presence of a dispersing block-copolymer, which acts via physical adsorption onto the PCBM and SWCNT moieties, does not prevent electron transfer at the P3HT-PCBM interface. These findings suggest a research perspective towards utilization of fibers of functional nanocomposites in fiber-based organic optoelectronic and photovoltaic devices. The latter can be developed in the textile-type large area photovoltaics or individual fiber-based solar cells that will broaden energy applications from macro-power tools to micro-nanoscale power conversion devices and smart textiles.

  7. Light-induced electron paramagnetic resonance evidence of charge transfer in electrospun fibers containing conjugated polymer/fullerene and conjugated polymer/fullerene/carbon nanotube blends

    International Nuclear Information System (INIS)

    Electrospun sub-micron fibers containing conjugated polymer (poly(3-hexylthiophene), P3HT) with a fullerene derivative, phenyl-C61-butyric acid methylester (PCBM) or a mixture of PCBM and single-walled carbon nanotubes (SWCNTs) were studied by light-induced electron paramagnetic resonance spectroscopy. The results provide experimental evidence of electron transfer between PCBM and P3HT components in both fiber systems and suggest that the presence of a dispersing block-copolymer, which acts via physical adsorption onto the PCBM and SWCNT moieties, does not prevent electron transfer at the P3HT-PCBM interface. These findings suggest a research perspective towards utilization of fibers of functional nanocomposites in fiber-based organic optoelectronic and photovoltaic devices. The latter can be developed in the textile-type large area photovoltaics or individual fiber-based solar cells that will broaden energy applications from macro-power tools to micro-nanoscale power conversion devices and smart textiles.

  8. Role of Nearby Charges on the Electronic Structure of π-Conjugated Molecules: Symmetric versus Asymmetric Charge Distributions in Oligo(p-phenyleneethynylene)

    DEFF Research Database (Denmark)

    Kirketerp, Maj-Britt Suhr; Ryhding, Torben; Støchkel, Kristian;

    2011-01-01

    Oligo(p-phenyleneethynylene)s (OPEs) are conjugated oligomers of great interest within materials science and molecular electronics on account of their highly applicable electronic and optical properties. Here we use gas-phase action spectroscopy to elucidate how the intrinsic electronic properties...

  9. Charge carrier mobility, photovoltaic, and electroluminescent properties of anthracene-based conjugated polymers bearing randomly distributed side chains

    Czech Academy of Sciences Publication Activity Database

    Usluer, Ö.; Kästner, C.; Abbas, M.; Ulbricht, C.; Cimrová, Věra; Wild, A.; Birckner, E.; Tekin, N.; Sariciftci, N. S.; Hoppe, H.; Rathgeber, S.; Egbe, D. A. M.

    2012-01-01

    Roč. 50, č. 16 (2012), s. 3425-3436. ISSN 0887-624X R&D Projects: GA MŠk(CZ) 1M06031 Institutional research plan: CEZ:AV0Z40500505 Keywords : conjugated polymers * organic field-effect transistors * organic solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.543, year: 2012

  10. Thermally evaporated fullerene (C70) to bridge the charge transport in between nanostructured zinc oxide and conjugated copolymer in hybrid solar cell

    International Nuclear Information System (INIS)

    We have investigated the effect of incorporating thin fullerene (C70) layer in between nanostructured ZnO and conjugated co-polymer PCDTBT (Poly [[9-(1-octylnonyl)-9H–carbazole-2,7-diyl]-2,5-thophenediyl-2,1, 3-benzothiadiazole- 4,7-diyl-2,5-thiophenediyl]) for photovoltaic device performance. The addition of the fullerene layer enhances the electron transfer at the heterojunction from polymer to the metal oxide. The reason for the enhanced performance is investigated and it is observed that the fullerene layer can improve charge transfer process thorough the reduction of the trap induced interfacial recombination. The fullerene introduction is also helping in effective charge transfer (CT) excitons dissociation and transport at the interface. Encouraging improvement of the device performance was observed with the incorporation of C70 in this kind of hybrid solar cells. (papers)

  11. Effects of Molecular Structure on Intramolecular Charge Carrier Transport in Dithieno [3,2-b: 2,3-d] Pyrrole-Based Conjugated Copolymers

    Directory of Open Access Journals (Sweden)

    Yoshihito Honsho

    2012-01-01

    Full Text Available Intramolecular mobility of positive charge carriers in conjugated polymer films based on dithieno [2,3-b: 2,3-d] pyrrole (DTP is studied by time-resolved microwave conductivity (TRMC. A series of DTP homopolymer and copolymers combined with phenyl, 2,2-biphenyl, thiophene, 2,2-bithiophene, and 9,9-dioctylfluorene were synthesized by Suzuki-Miyaura and Yamamoto coupling reactions. Polymers containing DTP unit are reported to show high value of hole mobility measured by FET method, and this type of polymers is expected to have stable HOMO orbitals which are important for hole transportation. Among these copolymers, DTP coupled with 9,9-dioctylfluorene copolymer showed the highest charge carrier mobility as high as 1.7 cm2/Vs, demonstrating an excellent electrical property on rigid copolymer backbones.

  12. Self-assembly and charge carrier transport of solution-processed conjugated polymer monolayers on dielectric surfaces with controlled sub-nanometer roughness

    Science.gov (United States)

    Li, Mengmeng; Hinkel, Felix; Müllen, Klaus; Pisula, Wojciech

    2016-04-01

    In recent years organic field-effect transistors have received extensive attention, however, it is still a great challenge to fabricate monolayer-based devices of conjugated polymers. In this study, one single layer of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) is directly dip-coated, and its self-assembly is precisely tuned from nanofibers to granular aggregates by controlling the dielectric roughness on a sub-nanometer scale. The charge carrier transport of the monolayer transistor exhibits a strong dependence on the dielectric roughness, which is attributed to the roughness-induced effects of higher densities of grain boundaries and charge trapping sites as well as surface scattering. These results mark a great advance in the bottom-up fabrication of organic electronics.In recent years organic field-effect transistors have received extensive attention, however, it is still a great challenge to fabricate monolayer-based devices of conjugated polymers. In this study, one single layer of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) is directly dip-coated, and its self-assembly is precisely tuned from nanofibers to granular aggregates by controlling the dielectric roughness on a sub-nanometer scale. The charge carrier transport of the monolayer transistor exhibits a strong dependence on the dielectric roughness, which is attributed to the roughness-induced effects of higher densities of grain boundaries and charge trapping sites as well as surface scattering. These results mark a great advance in the bottom-up fabrication of organic electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01082b

  13. Photosynthetic reaction center mimicry: low reorganization energy driven charge stabilization in self-assembled cofacial zinc phthalocyanine dimer-fullerene conjugate.

    Science.gov (United States)

    D'Souza, Francis; Maligaspe, Eranda; Ohkubo, Kei; Zandler, Melvin E; Subbaiyan, Navaneetha K; Fukuzumi, Shunichi

    2009-07-01

    By employing well-defined self-assembly methods, a biomimetic bacterial photosynthetic reaction center complex has been constructed, and photoinduced electron transfer originating in this supramolecular donor-acceptor conjugate has been investigated. The biomimetic model of the bacterial "special pair" donor, a cofacial zinc phthalocyanine dimer, was formed via potassium ion induced dimerization of 4,5,4',5',4'', 5'',4''',5'''-zinc tetrakis(1,4,7,10,13-pentaoxatridecamethylene)phthalocyanine. The dimer was subsequently self-assembled with functionalized fullerenes via "two-point" binding involving axial coordination and crown ether-alkyl ammonium cation complexation to form the donor-acceptor pair, mimicking the noncovalently bound entities of the bacterial photosynthetic reaction center. The adopted self-assembly methodology yielded a supramolecular complex of higher stability with defined geometry and orientation as revealed by the binding constant and computational optimized structure. Unlike the previously reported porphyrin analog, the present phthalocyanine macrocycle based model system exhibited superior electron-transfer properties including formation of a long-lived charge-separated state, a key step of the photosynthetic light energy conversion process. Detailed analysis of the kinetic data in light of the Marcus theory of electron transfer revealed that small reorganization energy of the relatively rigid phthalocyanine is primarily responsible for slower charge-recombination process. The importance of the cofacial dimer in stabilizing the charge-separated state is borne out in the present all-supramolecular "reaction center" donor-acceptor mimic. PMID:19505071

  14. Intense Ground-State Charge-Transfer Interactions in Low-Bandgap, Panchromatic Phthalocyanine-Tetracyanobuta-1,3-diene Conjugates.

    Science.gov (United States)

    Sekita, Michael; Ballesteros, Beatriz; Diederich, François; Guldi, Dirk M; Bottari, Giovanni; Torres, Tomás

    2016-04-25

    A cycloaddition-retroelectrocyclization reaction between tetracyanoethylene and two zinc phthalocyanines (Zn(II) Pcs) bearing one or four anilino-substituted alkynes has been used to install a strong, electron-accepting tetracyanobuta-1,3-diene (TCBD) between the electron-rich Zn(II) Pc and aniline moieties. A combination of photophysical, electrochemical, and spectroelectrochemical investigations with the Zn(II) Pc-TCBD-aniline conjugates, which present panchromatic absorptions in the visible region extending all the way to the near infrared, show that the formal replacement of the triple bond by TCBD has a dramatic effect on their ground- and excited-state features. In particular, the formation of extremely intense, ground-state charge-transfer interactions between Zn(II) Pc and the electron-accepting TCBD were observed, something unprecedented not only in Pc chemistry but also in TCBD-based porphyrinoid systems. PMID:27010677

  15. A single Tisbnd Osbnd C linkage induces interfacial charge-transfer transitions between TiO2 and a π-conjugated molecule

    Science.gov (United States)

    Fujisawa, Jun-ichi; Matsumura, Shingo; Hanaya, Minoru

    2016-07-01

    Interfacial charge-transfer (ICT) transitions between wide-band-gap semiconductors such as titanium dioxide (TiO2) and π-conjugated molecules enable the absorption of visible light with colorless organic compounds and also direct photoinduced electron transfers across the interfaces. ICT transitions have been reported to be induced by a double Tisbnd Osbnd C linkage of enediol compounds with two hydroxy groups to TiO2. In this Letter, we demonstrate that a single Tisbnd Osbnd C linkage of phenol with one hydroxy group can induce ICT transitions in the visible region. Our result widely opens up the range of organic compounds available for ICT transitions from diol compounds to mono-hydroxy compounds.

  16. Effect of axial ligation or pi-pi-type interactions on photochemical charge stabilization in "two-point" bound supramolecular porphyrin-fullerene conjugates.

    Science.gov (United States)

    D'Souza, Francis; Chitta, Raghu; Gadde, Suresh; Zandler, Melvin E; McCarty, Amy L; Sandanayaka, Atula S D; Araki, Yasuyaki; Ito, Osamu

    2005-07-18

    Two types of structurally well-defined, self-assembled zinc porphyrin-fullerene conjugates were formed by "two-point" binding strategies to probe the effect of axial ligation or pi-pi-type interactions on the photochemical charge stabilization in the supramolecular dyads. To achieve this, meso-tetraphenylporphyrin was functionalized to possess one or four [18]crown-6 moieties at different locations on the porphyrin macrocycle while fullerene was functionalized to possess an alkyl ammonium cation, and a pyridine or phenyl entities. As a result of the crown ether-ammonium cation complexation, and zinc-pyridine coordination or pi-pi-type interactions, stable zinc porphyrin-fullerene conjugates with defined distance and orientation were formed. Evidence for the zinc-pyridine complexation or pi-pi-type interactions was obtained from the spectral and computational studies. Steady-state and time-resolved emission studies revealed efficient quenching of the zinc-porphyrin singlet excited state in these dyads, and the measured rates of charge separation, k(CS) were found to be slightly better in the case of the dyads held by axial coordination and crown ether-cation complexation. Nanosecond transient absorption studies provided evidence for the electron transfer reactions, and these studies also revealed charge stabilization in these dyads. The lifetimes of the radical ion pairs were found to depend upon the type of porphyrins utilized to form the dyads, that is, porphyrin possessing the crown ether moiety at the ortho position of one of the phenyl rings yielded prolonged charge stabilized states. Addition of pyridine to the supramolecular dyads eliminated the zinc-pyridine coordination or pi-pi-type interactions of the "two-point" bound systems due to the formation of a new zinc-pyridine axial bond thus giving a unique opportunity to probe the effect of axial coordination or pi-pi interactions on k(CS) and k(CR). Under these conditions, the measured electron transfer rates

  17. Valence Band Dependent Charge Transport in Bulk Molecular Electronic Devices Incorporating Highly Conjugated Multi-[(Porphinato)Metal] Oligomers.

    Science.gov (United States)

    Bruce, Robert C; Wang, Ruobing; Rawson, Jeff; Therien, Michael J; You, Wei

    2016-02-24

    Molecular electronics offers the potential to control device functions through the fundamental electronic properties of individual molecules, but realization of such possibilities is typically frustrated when such specialized molecules are integrated into a larger area device. Here we utilize highly conjugated (porphinato)metal-based oligomers (PM(n) structures) as molecular wire components of nanotransfer printed (nTP) molecular junctions; electrical characterization of these "bulk" nTP devices highlights device resistances that depend on PM(n) wire length. Device resistance measurements, determined as a function of PM(n) molecular length, were utilized to evaluate the magnitude of a phenomenological β corresponding to the resistance decay parameter across the barrier; these data show that the magnitude of this β value is modulated via porphyrin macrocycle central metal atom substitution [β(PZn(n); 0.065 Å(-1)) < β(PCu(n); 0.132 Å(-1)) < β(PNi(n); 0.176 Å(-1))]. Cyclic voltammetric data, and ultraviolet photoelectron spectroscopic studies carried out at gold surfaces, demonstrate that these nTP device resistances track with the valence band energy levels of the PM(n) wire, which were modulated via porphyrin macrocycle central metal atom substitution. This study demonstrates the ability to fabricate "bulk" and scalable electronic devices in which function derives from the electronic properties of discrete single molecules, and underscores how a critical device function--wire resistance--may be straightforwardly engineered by PM(n) molecular composition. PMID:26829704

  18. How does the increment of hetero-cyclic conjugated moieties affect electro-optical and charge transport properties of novel naphtha-difuran derivatives? A computational approach.

    Science.gov (United States)

    Chaudhry, Aijaz Rasool; Ahmed, R; Irfan, Ahmad; Muhammad, Shabbir; Shaari, A; Al-Sehemi, Abdullah G

    2014-12-01

    We have investigated computationally the effects of π-conjugation extension on naphtha[2,1-b:6,5-b'] difuran (DPNDF); where we increase the number of fused NDF (central core) and furan rings in the parent molecule. The molecular structures of all analogues have been optimized at the ground (S0) and first excited (S1) states using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. Then highest occupied molecular orbitals (HOMOs), the lowest unoccupied molecular orbitals (LUMOs), photophysical properties, adiabatic/vertical electron affinities (EAa)/(EAv), adiabatic/vertical ionization potentials (IPa)/(IPv), and hole/electron reorganization energies λh/λe have been investigated. The effect of NDF and furan rings on structural and electro-optical properties has also been studied. Our calculated reorganization energies of 1a, 1b, and 2c reveal them, materials with balanced hole/electron charge transport, whereas 2a and 2b are good hole-transport materials. By increasing the number of furan rings; the photostability was augmented in 2a, 2b, and 2c. PMID:25503703

  19. Conjugal violence

    Directory of Open Access Journals (Sweden)

    Simona Mihaiu

    2015-10-01

    Full Text Available Scientific knowledge of different aspects related to conjugal violence is highly important for people directly involved, such as researchers, practitioners and the entire society. In this respect, globally, specialised studies continue to advance, offer correct definitions, clear descriptions, convincing assessments to certain issues, encouraging thus long-term research, since some specialists have managed to overcome restrictive or ideological methods and explanations. Moreover, in practice, debates reach almost all social, political and legal dimensions regarding appropriate and efficient forms of preventing conjugal violence. Unfortunately, in Romania there are fewer research and prevention approaches of this social problem. In general, attention is directed to domestic violence and conjugal violence is dealt with only implicitly. Considering the given context, the aim of the paper is to outline, by analysing specialised literature, a new research direction and implicitly, social intervention. I specify that this article represents a stage in the ongoing postdoctoral research project, entitled "Conjugal homicide. Aggressors and victims".

  20. Elastic properties of perovskite ATiO3 (A = Be, Mg, Ca, Sr, and Ba) and PbBO3 (B = Ti, Zr, and Hf): First principles calculations

    International Nuclear Information System (INIS)

    The mechanical properties of perovskite oxides depend on two metal oxide lattices that are intercalated. This provides an opportunity for separate tuning of hardness, Poisson's ratio (transverse expansion in response to the compression), and shear strength. The elastic constants of series of perovskite oxides were studied by first principles approach. Both A-site and B-site cations were systematically varied in order to see their effects on the elastic parameters. To study the effects of A-site cations, we studied the elastic properties of perovskite ATiO3 for A being Be, Mg, Ca, Sr, or Ba, one at a time. Similarly, for B-site cations, we studied the elastic properties of PbBO3 for B being Ti, Zr, or Hf, one at a time. The density functional first principles calculations with local density approximation (LDA) and generalized gradient approximation (GGA) were employed. It is found that the maximum C11 elastic constant is achieved when the atomic size of the cations at A-site and B-site are comparable. We also found that C12 elastic constant is sensitive to B-site cations while C44 elastic constant is more sensitive to A-site cations. Details and explanations for such dependencies are discussed

  1. Ultrafast Photoinduced Charge Separation Leading to High-Energy Radical Ion-Pairs in Directly Linked Corrole-C60 and Triphenylamine-Corrole-C60 Donor-Acceptor Conjugates.

    Science.gov (United States)

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

    2015-12-01

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

  2. Position-Dependent Extension of π-Conjugation in D-π-A Dye Sensitizers and the Impact on the Charge-Transfer Properties

    OpenAIRE

    Wielopolski, Mateusz; Kim, Jong-Hyung; Jung, Young-Sam; Yu, Young-Jae; Kay, Kwang-Yol; Thomas W. Holcombe; Zakeeruddin, Shaik M.; Grätzel, Michael; Moser, Jacques-E.

    2013-01-01

    A series of five organic donor-π-bridge-acceptor (D-π-A) sensitizers is investigated within the context of their photoinduced charge-transfer properties. Thereby, the focus is set on the impact of structural modifications of the molecular architecture on the π-systems of the dyes. In particular, two different modes of systematic extension of the sensitizers’ π-systems, namely, (i) within the electron donating site and (ii) within the π-bridge, are investigated by means of steady-state and tim...

  3. Modulating the generation of long-lived charge separated states exclusively from the triplet excited states in palladium porphyrin-fullerene conjugates

    Science.gov (United States)

    O. Obondi, Christopher; Lim, Gary N.; Churchill, Brittani; Poddutoori, Prashanth K.; van der Est, Art; D'Souza, Francis

    2016-04-01

    This study demonstrates molecular engineering of a series of donor-acceptor systems to allow control of the lifetime and initial spin multiplicity of the charge-separated state. By tuning the rate of intersystem crossing (ISC) and the donor-acceptor distance, electron transfer can be made to occur exclusively from the triplet excited state of the electron donor resulting in long-lived charge separation. To achieve this, three new palladium porphyrin-fullerene donor-acceptor systems were synthesized. The heavy Pd atom enhances the rate of ISC in the porphyrin and the rates of electron and energy transfer are modulated by varying the redox potential of the porphyrin and the porphyrin-fullerene distance. In the case of the meso-tris(tolyl)porphyrinato palladium(ii)-fulleropyrrolidine, the donor-acceptor distance is relatively long (13.1 Å) and the driving force for electron transfer is low. As a result, excitation of the porphyrin leads to rapid ISC followed by triplet-triplet energy transfer to fullerene. When the fullerene is bound directly to the porphyrin shortening the donor-acceptor distance to 2.6 Å electron transfer from the singlet excited palladium porphyrin leading to the generation of a short-lived charge separated state is the main process. Finally, when the palladium porphyrin is substituted with three electron rich triphenylamine entities, the lower oxidation potential of the porphyrin and appropriate donor-acceptor distance (~13 Å), lead to electron transfer exclusively from the triplet excited state of palladium porphyrin with high quantum yield. The results show that when electron transfer occurs from the triplet state, its increased lifetime allows the distance between the donor and acceptor to be increased which results in a longer lifetime for the charge separated state.This study demonstrates molecular engineering of a series of donor-acceptor systems to allow control of the lifetime and initial spin multiplicity of the charge-separated state

  4. Concatenated Conjugate Codes

    CERN Document Server

    Hamada, M

    2006-01-01

    A conjugate code pair is defined as a pair of linear codes either of which contains the dual of the other. A conjugate code pair represents the essential structure of the corresponding Calderbank-Shor-Steane (CSS) quantum code. It is known that conjugate code pairs are applicable to (quantum) cryptography. We give a construction method for efficiently decodable conjugate code pairs.

  5. Colloidal gold--low density lipoprotein conjugates as membrane receptor probes.

    OpenAIRE

    Handley, D. A.; Arbeeny, C M; Witte, L D; Chien, S

    1981-01-01

    We have developed a method for conjugating low density lipoproteins (LDL) with colloidal gold. Conjugation, complete after 1 min, occurs by electrostatic adsorption of the LDL to the negatively charged gold particle. Each conjugate consists of approximately eight biologically active LDL molecules clustered around a central 19-nm gold granule. Acidic (pH 4), alkaline (pH 9), or high ionic (600 milliosmolar NaCl) environments do not dissociate the conjugate. Colloidal gold is an electron-dense,...

  6. Conjugations on 6-Manifolds

    OpenAIRE

    Olbermann, Martin

    2007-01-01

    Conjugation spaces are spaces with involution such that the fixed point set of the involution has Z/2-cohomology isomorphic to the Z/2-cohomology of the space itself, with the little difference that all degrees are divided by two (e.g. CP^n with the complex conjugation). One also requires that a certain conjugation equation is fulfilled. I give a new characterization of conjugation spaces and apply it to the following realization question: given M, a closed orientable 3-manifold, is there a 6...

  7. Cross-conjugation and quantum interference: a general correlation?

    DEFF Research Database (Denmark)

    Valkenier, Hennie; Guedon, Constant M.; Markussen, Troels; Thygesen, Kristian Sommer; van der Molen, Sense J.; Hummelen, Jan C.

    2014-01-01

    We discuss the relationship between the pi-conjugation pattern, molecular length, and charge transport properties of molecular wires, both from an experimental and a theoretical viewpoint. Specifically, we focus on the role of quantum interference in the conductance properties of cross-conjugated......We discuss the relationship between the pi-conjugation pattern, molecular length, and charge transport properties of molecular wires, both from an experimental and a theoretical viewpoint. Specifically, we focus on the role of quantum interference in the conductance properties of cross......-conjugated molecules. For this, we compare experiments on two series of dithiolated wires. The first set we synthesized consists of three dithiolated oligo(phenylene ethynylene) (OPE) benchmark compounds with increasing length. The second series synthesized comprises three molecules with different pi......-conjugation patterns, but identical lengths, i.e. an anthracene (linear conjugation), an anthraquinone (cross-conjugation), and a dihydroanthracene (broken conjugation) derivative. To benchmark reliable trends, conductance experiments on these series have been performed by various techniques. Here, we compare data...

  8. Segmented conjugated polymers

    Indian Academy of Sciences (India)

    G Padmanaban; S Ramakrishnan

    2003-08-01

    Segmented conjugated polymers, wherein the conjugation is randomly truncated by varying lengths of non-conjugated segments, form an interesting class of polymers as they not only represent systems of varying stiffness, but also ones where the backbone can be construed as being made up of chromophores of varying excitation energies. The latter feature, especially when the chromophores are fluorescent, like in MEHPPV, makes these systems particularly interesting from the photophysics point of view. Segmented MEHPPV- samples, where x represents the mole fraction of conjugated segments, were prepared by a novel approach that utilizes a suitable precursor wherein selective elimination of one of the two eliminatable groups is affected; the uneliminated units serve as conjugation truncations. Control of the composition x of the precursor therefore permits one to prepare segmented MEHPPV- samples with varying levels of conjugation (elimination). Using fluorescence spectroscopy, we have seen that even in single isolated polymer chains, energy migration from the shorter (higher energy) chromophores to longer (lower energy) ones occurs – the extent of which depends on the level of conjugation. Further, by varying the solvent composition, it is seen that the extent of energy transfer and the formation of poorly emissive inter-chromophore excitons are greatly enhanced with increasing amounts of non-solvent. A typical S-shaped curve represents the variation of emission yields as a function of composition suggestive of a cooperative collapse of the polymer coil, reminiscent of conformational transitions seen in biological macromolecules.

  9. Biological Sensing and DNA Templated Electronics Using Conjugated Polymers

    OpenAIRE

    Björk, Per

    2007-01-01

    Conjugated polymers have been found useful in a wide range of applications such as solar cells, sensor elements and printed electronics, due to their optical and electronic properties. Functionalization with charged side chains has enabled water solubility, resulting in an enhanced interaction with biomolecules. This thesis focus on the emerging research fields, where these conjugated polyelectrolytes (CPEs) are combined with biomolecules for biological sensing and DNA nanowire assembling. CP...

  10. Solution assembly of conjugated polymers

    Science.gov (United States)

    Bokel, Felicia A.

    This dissertation focuses on the solution-state polymer assembly of conjugated polymers with specific attention to nano- and molecular-scale morphology. Understanding how to control these structures holds potential for applications in polymer-based electronics. Optimization of conjugated polymer morphology was performed with three objectives: 1) segregation of donor and acceptor materials on the nanometer length-scale, 2) achieving molecular-scale ordering in terms of crystallinity within distinct domains, and 3) maximizing the number and quality of well-defined donor/acceptor interfaces. Chapter 1 introduces the development of a mixed solvent method to create crystalline poly(3-hexyl thiophene) (P3HT) fibrils in solution. Chapter 2 describes fibril purification and approaches to robust and functional fibrils, while chapters 3 and 4 demonstrate the formation of hybrid nanocomposite wires of P3HT and cadmium selenide (CdSe) nanoparticles by two methods: 1) co-crystallization of free and P3HT-grafted CdSe for composite nanowires and 2) direct attachment of CdSe nanoparticles at fibril edges to give superhighway structures. These composite structures show great potential in the application of optoelectronic devices, such as the active layer of solar cells. Finally, ultrafast photophysical characterization of these polymers, using time-resolved photoluminescence and transient absorption, was performed to determine the aggregation types present in suspended fibrils and monitor the formation and decay of charged species in fibrils and donor-acceptor systems.

  11. Polymers for Protein Conjugation

    Directory of Open Access Journals (Sweden)

    Gianfranco Pasut

    2014-01-01

    Full Text Available Polyethylene glycol (PEG at the moment is considered the leading polymer for protein conjugation in view of its unique properties, as well as to its low toxicity in humans, qualities which have been confirmed by its extensive use in clinical practice. Other polymers that are safe, biodegradable and custom-designed have, nevertheless, also been investigated as potential candidates for protein conjugation. This review will focus on natural polymers and synthetic linear polymers that have been used for protein delivery and the results associated with their use. Genetic fusion approaches for the preparation of protein-polypeptide conjugates will be also reviewed and compared with the best known chemical conjugation ones.

  12. CONJUGATED POLYMERS AND POLYELECTROLYTES IN SOLAR PHOTOCONVERSION, Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Schanze, Kirk S [University of Florida

    2014-08-05

    This DOE-supported program investigated the fundamental properties of conjugated polyelectrolytes, with emphasis placed on studies of excited state energy transport, self-assembly into conjugated polyelectroyte (CPE) based films and colloids, and exciton transport and charge injection in CPE films constructed atop wide bandgap semiconductors. In the most recent grant period we have also extended efforts to examine the properties of low-bandgap donor-acceptor conjugated polyelectrolytes that feature strong visible light absorption and the ability to adsorb to metal-oxide interfaces.

  13. Notes on partial conjugation

    OpenAIRE

    Fang, Chuying; He, Xuhua

    2011-01-01

    In this notes, we will give an exposition of some results on the method of partial conjugation action. We first discuss the partial conjugation action of a parabolic subgroup of a Coxeter group. We then discuss some applications to Lusztig's $G$-stable pieces and its affine generalization. We also discuss some recent work on the $\\s$-conjugacy classes of loop groups and affine Deligne-Lusztig varieties.

  14. Photoconductive properties of conjugated polymers

    CERN Document Server

    Halls, J J M

    1997-01-01

    The research described in my dissertation has involved the fabrication and characterisation of photovoltaic cells based on conjugated polymers, including the widely studied polymer poly(p-phenylenevinylene). These materials have semiconducting properties which arise from the delocalisation of electrons along the pi-electron systems of the polymer chains. Research into these materials is motivated both by their novel electronic properties, and also their potential for use in a wide range of applications including light-emitting diodes (LEDs), thin-film transistors, and photovoltaic cells (solar cells and light detectors). Light absorbed in a photovoltaic cell generates opposite charges which are collected at two different electrodes, giving rise to an electric current

  15. Polymeric Micelles for Delivery of Poorly Soluble Drugs: Preparation and Anticancer Activity In Vitro of Paclitaxel Incorporated into Mixed Micelles Based on Poly(ethylene Glycol)-Lipid Conjugate and Positively Charged Lipids

    OpenAIRE

    Wang, Junping; MONGAYT, DIMITRY; Torchilin, Vladimir P.

    2005-01-01

    Paclitaxel-loaded mixed polymeric micelles consisting of poly(ethylene glycol)-distearoyl phosphoethanolamine conjugates (PEG-PE), solid triglycerides (ST), and cationic Lipofectin® lipids (LL) have been prepared. Micelles with the optimized composition (PEG-PE/ST/LL/paclitaxel = 12/12/2/1 by weight) had an average micelle size of about 100 nm, and zeta-potential of about 26 mV. Micelles were stable and did not release paclitaxel when stored at 4°C in the darkness (just 2.9% of paclitaxel hav...

  16. Peptide-Carrier Conjugation

    DEFF Research Database (Denmark)

    Hansen, Paul Robert

    To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined.......To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

  17. Qualidade conjugal: mapeando conceitos

    OpenAIRE

    Clarisse Mosmann; Adriana Wagner; Terezinha Féres-Carneiro

    2006-01-01

    Apesar da ampla utilização do conceito de qualidade conjugal, identifica-se falta de clareza conceitual acerca das variáveis que o compõem. Esse artigo apresenta revisão da literatura na área com o objetivo de mapear o conceito de qualidade conjugal. Foram analisadas sete principais teorias sobre o tema: Troca Social, Comportamental, Apego, Teoria da Crise, Interacionismo Simbólico. Pelos postulados propostos nas diferentes teorias, podem-se identificar três grupos de variáveis fundamentais n...

  18. Determination of stability constants of tauro- and glyco-conjugated bile salts with the negatively charged sulfobutylether-β-cyclodextrin: comparison of affinity capillary electrophoresis and isothermal titration calorimetry and thermodynamic analysis of the interaction

    DEFF Research Database (Denmark)

    Holm, René; Østergaard, Jesper; Schönbeck, Jens Christian Sidney;

    2014-01-01

    -complexed drugs upon oral administration. This makes a good understanding of this particular interaction important for rational drug formulation. SBEβCD is a modified CD, which has attracted particular interest in formulation science. It is unique in the sense that it carries approximately seven negatively...... charged side chains, which can potentially interact electrostatically with the guest molecule. Bile salts are negatively charged at physiological pH, and the concomitant repulsion from SBEβCD could potentially reduce their affinity for this CD and hence their ability to expel drugs delivered as SBEβ...

  19. Stabilized polyacrylic saccharide protein conjugates

    Science.gov (United States)

    Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

    1996-02-20

    This invention is directed to water soluble protein polymer conjugates which are stable in hostile environments. The conjugate comprises a protein which is linked to an acrylic polymer at multiple points through saccharide linker groups. 16 figs.

  20. Betaine conjugated cationic pullulan as effective gene carrier.

    Science.gov (United States)

    Ambattu, Lizebona August; Rekha, M R

    2015-01-01

    Polyethyleneimne (PEI) is a very efficient transfecting agent but is toxic due to high charge density. To generate a vector which is efficient and less cytotoxic, PEI was conjugated with pullulan (PPEI). Further conjugation was done on PPEI with zwitter ionic betaine which possess antifouling property. PEI of molecular weight 1.2, 2, and 10 kDa were used in the study. Buffering capacity of pullulan-PEI-betaine (PPB) conjugates was found to be sufficient enough for the polymers to make endosomal escape. The polymers proved to be less cytotoxic and highly hemocompatible than PEI. Nuclear localization of YOYO tagged DNA was observed with the nanoplexes developed using PPEI and PPBs of PEI 10 kDa. Transfection efficiency was evaluated using p53 expressing gene and the live dead assay demonstrated very high transfection efficiency with PPB conjugates of PEI 10 kDa. PMID:25304750

  1. DNA-cell conjugates

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Shih-Chia; Francis, Matthew B.; Bertozzi, Carolyn; Mathies, Richard; Chandra, Ravi; Douglas, Erik; Twite, Amy; Toriello, Nicholas; Onoe, Hiroaki

    2016-05-03

    The present invention provides conjugates of DNA and cells by linking the DNA to a native functional group on the cell surface. The cells can be without cell walls or can have cell walls. The modified cells can be linked to a substrate surface and used in assay or bioreactors.

  2. Dihydroazulene-buckminsterfullerene conjugates

    DEFF Research Database (Denmark)

    Santella, Marco; Mazzanti, Virginia; Jevric, Martyn; Parker, Christian Richard; Broman, Søren Lindbæk; Bond, Andrew; Nielsen, Mogens Brøndsted

    2012-01-01

    combined the two units with the overall aim to elucidate how C(60) influences the DHA-VHF switching events. Efficient synthetic protocols for making covalently linked DHA-C(60) conjugates were developed, using Prato, Sonogashira, Hay, and Cadiot-Chodkiewicz reactions. These syntheses provide as well a...

  3. Conjugation in "Escherichia coli"

    Science.gov (United States)

    Phornphisutthimas, Somkiat; Thamchaipenet, Arinthip; Panijpan, Bhinyo

    2007-01-01

    Bacterial conjugation is a genetic transfer that involves cell-to-cell between donor and recipient cells. With the current method used to teach students in genetic courses at the undergraduate level, the transconjugants are identified using bacterial physiology and/or antibiotic resistance. Using physiology, however, is difficult for both…

  4. Extreme electron polaron spatial delocalization in π-conjugated materials.

    Science.gov (United States)

    Rawson, Jeff; Angiolillo, Paul J; Therien, Michael J

    2015-11-10

    The electron polaron, a spin-1/2 excitation, is the fundamental negative charge carrier in π-conjugated organic materials. Large polaron spatial dimensions result from weak electron-lattice coupling and thus identify materials with unusually low barriers for the charge transfer reactions that are central to electronic device applications. Here we demonstrate electron polarons in π-conjugated multiporphyrin arrays that feature vast areal delocalization. This finding is evidenced by concurrent optical and electron spin resonance measurements, coupled with electronic structure calculations that suggest atypically small reorganization energies for one-electron reduction of these materials. Because the electron polaron dimension can be linked to key performance metrics in organic photovoltaics, light-emitting diodes, and a host of other devices, these findings identify conjugated materials with exceptional optical, electronic, and spintronic properties. PMID:26512097

  5. Model of the hole mobility in linear conjugated polymers

    Czech Academy of Sciences Publication Activity Database

    Toman, Petr; Menšík, Miroslav; Pfleger, Jiří

    Thessaloniki : Laboratory for Thin Films, Nanosystems & Nanometrology (LTFN), Aristotle University of Thessaloniki, 2015. s. 33. [International Symposium on Flexible Organic Electronics /8./ - ISFOE15. 06.07.2015-09.07.2015, Thessaloniki] R&D Projects: GA ČR(CZ) GA15-05095S Institutional support: RVO:61389013 Keywords : charge carrier transport * conjugated polymer * disorder Subject RIV: BM - Solid Matter Physics ; Magnetism

  6. Conjugate gradient method

    Czech Academy of Sciences Publication Activity Database

    Segeth, Karel

    Liberec : Technická univerzita v Liberci, 2006, s. 335-341. ISBN 80-7372-055-8. [International Conference Presentation of Mathematics ICPM ´05. Liberec (CZ), 20.09.2005-23.09.2005] R&D Projects: GA ČR(CZ) GA201/04/1503 Institutional research plan: CEZ:AV0Z10190503 Keywords : linear algebraic system * conjugate gradient method * preconditioning Subject RIV: BA - General Mathematics

  7. Anti- (conjugate) linearity

    Science.gov (United States)

    Uhlmann, Armin

    2016-03-01

    This is an introduction to antilinear operators. In following Wigner the terminus antilinear is used as it is standard in Physics. Mathematicians prefer to say conjugate linear. By restricting to finite-dimensional complex-linear spaces, the exposition becomes elementary in the functional analytic sense. Nevertheless it shows the amazing differences to the linear case. Basics of antilinearity is explained in sects. 2, 3, 4, 7 and in sect. 1.2: Spectrum, canonical Hermitian form, antilinear rank one and two operators, the Hermitian adjoint, classification of antilinear normal operators, (skew) conjugations, involutions, and acq-lines, the antilinear counterparts of 1-parameter operator groups. Applications include the representation of the Lagrangian Grassmannian by conjugations, its covering by acq-lines. As well as results on equivalence relations. After remembering elementary Tomita-Takesaki theory, antilinear maps, associated to a vector of a two-partite quantum system, are defined. By allowing to write modular objects as twisted products of pairs of them, they open some new ways to express EPR and teleportation tasks. The appendix presents a look onto the rich structure of antilinear operator spaces.

  8. Conjugate flow action functionals

    International Nuclear Information System (INIS)

    We present a new general framework to construct an action functional for a non-potential field theory. The key idea relies on representing the governing equations relative to a diffeomorphic flow of curvilinear coordinates which is assumed to be functionally dependent on the solution field. Such flow, which will be called the conjugate flow, evolves in space and time similarly to a physical fluid flow of classical mechanics and it can be selected in order to symmetrize the Gâteaux derivative of the field equations with respect to suitable local bilinear forms. This is equivalent to requiring that the governing equations of the field theory can be derived from a principle of stationary action on a Lie group manifold. By using a general operator framework, we obtain the determining equations of such manifold and the corresponding conjugate flow action functional. In particular, we study scalar and vector field theories governed by second-order nonlinear partial differential equations. The identification of transformation groups leaving the conjugate flow action functional invariant could lead to the discovery of new conservation laws in fluid dynamics and other disciplines

  9. Functionalized Conjugated Polyelectrolytes for Biological Sensing and Imaging.

    Science.gov (United States)

    Zhan, Ruoyu; Liu, Bin

    2016-06-01

    Conjugated polyelectrolytes (CPEs) are macromolecules with highly delocalized π-conjugated backbones and charged side chains, which are unique types of active materials, with wide applications in optoelectronics, sensing, imaging, and therapy. By attaching specific groups (e.g., recognition elements, magnetic resonance (MR) contrast agents, gene carriers, and drugs) to the side chain or backbone of CPEs, functionalized CPEs have been developed and used for specific biological applications. In this account, we summarize the recent progress of functionalized CPEs with respect to their synthesis and biomedical applications. Future perspectives are also discussed at the end. PMID:27230631

  10. Side Chain Engineering in Solution-Processable Conjugated Polymers

    KAUST Repository

    Mei, Jianguo

    2014-01-14

    Side chains in conjugated polymers have been primarily utilized as solubilizing groups. However, these side chains have roles that are far beyond. We advocate using side chain engineering to tune a polymer\\'s physical properties, including absorption, emission, energy level, molecular packing, and charge transport. To date, numerous flexible substituents suitable for constructing side chains have been reported. In this Perspective article, we advocate that the side chain engineering approach can advance better designs for next-generation conjugated polymers. © 2013 American Chemical Society.

  11. Charge Distributions in Transverse Coordinate Space and in Impact Parameter Space

    OpenAIRE

    Hwang, Dae Sung; Kim, Dong Soo; Kim, Jonghyun

    2008-01-01

    We study the charge distributions of the valence quarks inside nucleon in the transverse coordinate space, which is conjugate to the transverse momentum space. We compare the results with the charge distributions in the impact parameter space.

  12. Nonlinear Conjugate Gradient Methods

    Czech Academy of Sciences Publication Activity Database

    Lukšan, Ladislav; Vlček, Jan

    Praha: Matematický ústav AV ČR, v.v.i, 2015 - (Chleboun, J.; Přikryl, P.; Segeth, K.; Šístek, J.; Vejchodský, T.), s. 130-135 ISBN 978-80-85823-64-6. [Programs and Algorithms of Numerical Mathematics /17./. Dolní Maxov (CZ), 08.06.2014-13.06.2014] Institutional support: RVO:67985807 Keywords : minimization * nonlinear conjugate gradient methods * comparison of methods * efficiency of methods Subject RIV: BA - General Mathematics http://dml.cz/handle/10338.dmlcz/702674

  13. Conjugate points in Euler's elastic problem

    CERN Document Server

    Sachkov, Yu L

    2007-01-01

    For the classical Euler's elastic problem, conjugate points are described. Inflectional elasticae admit the first conjugate point between the first and the third inflection points. All the rest elasticae do not have conjugate points.

  14. Conjugation of DNA to Silanized Colloidal Semiconductor Nanocrystalline Quantum Dots

    International Nuclear Information System (INIS)

    Water-soluble, highly fluorescent, silanized semiconductor nanocrystals with different surface charges were synthesized. To covalently attach the nanocrystals to biological macromolecules with a variety of mild coupling chemistries, the outermost siloxane shells were derivatized with thiol, amino, or carboxyl functional groups. Single- or double-stranded DNA was coupled to the nanocrystal surfaces by using commercially available bifunctional cross-linker. Conjugation had little effect on the optical properties of the nanocrystals, and the resulting conjugates were more stable than previously reported systems. By using the strategies developed in this study, most biomolecules can be covalently coupled to semiconductor nanocrystals. These nanocrystal-DNA conjugates promise to be a versatile tool for fluorescence imaging and probing of biological systems

  15. Generalized conjugate gradient squared

    Energy Technology Data Exchange (ETDEWEB)

    Fokkema, D.R.; Sleijpen, G.L.G. [Utrecht Univ. (Netherlands)

    1994-12-31

    In order to solve non-symmetric linear systems of equations, the Conjugate Gradient Squared (CGS) is a well-known and widely used iterative method. In practice the method converges fast, often twice as fast as the Bi-Conjugate Gradient method. This is what you may expect, since CGS uses the square of the BiCG polynomial. However, CGS may suffer from its erratic convergence behavior. The method may diverge or the approximate solution may be inaccurate. BiCGSTAB uses the BiCG polynomial and a product of linear factors in an attempt to smoothen the convergence. In many cases, this has proven to be very effective. Unfortunately, the convergence of BiCGSTAB may stall when a linear factor (nearly) degenerates. BiCGstab({ell}) is designed to overcome this degeneration of linear factors. It generalizes BiCGSTAB and uses both the BiCG polynomial and a product of higher order factors. Still, CGS may converge faster than BiCGSTAB or BiCGstab({ell}). So instead of using a product of linear or higher order factors, it may be worthwhile to look for other polynomials. Since the BiCG polynomial is based on a three term recursion, a natural choice would be a polynomial based on another three term recursion. Possibly, a suitable choice of recursion coefficients would result in method that converges faster or as fast as CGS, but less erratic. It turns out that an algorithm for such a method can easily be formulated. One particular choice for the recursion coefficients leads to CGS. Therefore one could call this algorithm generalized CGS. Another choice for the recursion coefficients leads to BiCGSTAB. It is therefore possible to mix linear factors and some polynomial based on a three term recursion. This way one may get the best of both worlds. The authors will report on their findings.

  16. Electrochromic in conjugated polymers

    International Nuclear Information System (INIS)

    This revision considered object the description of one of the materials with the greatest potential in the field of electrochromic (mainly in the visible region): the conjugated polymers (CP), area of enormous potential both now and in a short time ahead. The CP are insulating materials and organic semiconductors in a state not doped. They can be doped positively or negatively being observed a significant increase in the conductivity and being generated a color change in these materials. The understanding of how optical properties vary based on the chemical structure of the polymer or its mixtures and more precisely of the alternatives that can be entered into the conjugated system or π system to obtain a material that besides to be flexible, environmentally stable, presents the colored states. The revision was centred chiefly in the polypyrrole (Ppy), the polythiophene (PTh) and their derivatives such as poly (3.4-ethylenedioxythiophene) (PEDOT). The advantage of using monomers with variable structure, to adjust the composition of the copolymer, or to blend with the PC, allows to obtain a variety of colored states that can be modulated through the visible spectrum and even with applications to wavelengths outside of this region. Because the PC presented at least two different colored states can be varied continuously as a function of the voltage applied. In some cases, they may submit multicoloured statements, which offers a range of possibilities for their application in flexible electronic devices type screens and windows. Applications include smart windows, camouflage clothing and data screens. This type of material is emerging as one of the substitutes of the traditional inorganic semiconductor, with the advantage of its low cost, high flexibility and the possibility to generate multiple colors through the handling of the monomers in the structure and control of energy of his band gap. (author)

  17. Optical observations geomagnetically conjugate to sprite-producing lightning discharges

    Directory of Open Access Journals (Sweden)

    R. A. Marshall

    2005-09-01

    Full Text Available Theoretical studies have predicted that large positive cloud-to-ground discharges can trigger a runaway avalanche process of relativistic electrons, forming a geomagnetically trapped electron beam. The beam may undergo pitch angle and energy scattering during its traverse of the Earth's magnetosphere, with a small percentage of electrons remaining in the loss cone and precipitating in the magnetically conjugate atmosphere. In particular, N2 1P and N2+1N optical emissions are expected to be observable. In July and August 2003, an attempt was made to detect these optical emissions, called "conjugate sprites", in correlation with sprite observations in Europe near . Sprite observations were made from the Observatoire du Pic du Midi (OMP in the French Pyrenées, and VLF receivers were installed in Europe to detect causative sferics and ionospheric disturbances associated with sprites. In the Southern Hemisphere conjugate region, the Wide-angle Array for Sprite Photometry (WASP was deployed at the South African Astronomical Observatory (SAAO, near Sutherland, South Africa, to observe optical emissions with a field-of-view magnetically conjugate to the Northern Hemisphere observing region. Observations at OMP revealed over 130 documented sprites, with WASP observations covering the conjugate region successfully for 30 of these events. However, no incidences of optical emissions in the conjugate hemisphere were found. Analysis of the conjugate optical data from SAAO, along with ELF energy measurements from Palmer Station, Antarctica, and charge-moment analysis, show that the lightning events during the course of this experiment likely had insufficient intensity to create a relativistic beam.

    Keywords. Ionosphere (Ionsophere-magnetosphere interactions; Ionospheric disturbances; Instruments and techniques

  18. Star-Shaped Conjugated Systems

    Directory of Open Access Journals (Sweden)

    Heiner Detert

    2010-05-01

    Full Text Available The present review deals with the preparation and the properties of star-shaped conjugated compounds. Three, four or six conjugated arms are attached to cross-conjugated cores, which consist of single atoms (B, C+, N, benzene or azine rings or polycyclic ring systems, as for example triphenylene or tristriazolotriazine. Many of these shape-persistent [n]star compounds tend to π-stacking and self-organization, and exhibit interesting properties in materials science: Linear and non-linear optics, electrical conductivity, electroluminescence, formation of liquid crystalline phases, etc.

  19. Controlled Self Assembly of Conjugated Polymer Containing Block Copolymers

    OpenAIRE

    McCulloch, Bryan

    2012-01-01

    The discovery and development of conjugated polymers has led to a large and vibrant research field due to their unique semiconducting properties and possibility of offering a completely new paradigm due to their abundant, lightweight, flexible and solution processable properties. In particular, the optoelectronic properties of these materials make them very well suited to applications such as organic light emitting diodes or organic photovoltaics and their relatively high charge mobility als...

  20. Nanoscopic studies of conjugated polymer blends by (electric) scanning probe microscopy

    OpenAIRE

    Sun, L

    2010-01-01

    Conjugated polymers and conjugated polymer blends have attracted great interest due to their potential applications in biosensors and organic electronics. The sub-100 nm morphology of these materials is known to heavily influence their electromechanical properties and the performance of devices they are part of. Electromechanical properties include charge injection, transport, recombination, and trapping, the phase behavior and the mechanical robustness of polymers and blends. Electrical scan...

  1. Conjugate Codes and Applications to Cryptography

    CERN Document Server

    Hamada, M

    2006-01-01

    A conjugate code pair is defined as a pair of linear codes such that one contains the dual of the other. The conjugate code pair represents the essential structure of the corresponding Calderbank-Shor-Steane (CSS) quantum code. It is argued that conjugate code pairs are applicable to quantum cryptography in order to motivate studies on conjugate code pairs.

  2. Linear maps respecting unitary conjugation

    OpenAIRE

    Bhat, B V Rajarama

    2011-01-01

    We characterize linear maps on von Neumann algebras which leave every unital subalgebra invariant. We use this characterization to determine linear maps which respect unitary conjugation, answering a question of M. S. Moslehian.

  3. Conjugation-Length Dependence of Spin-Dependent Exciton Formation Rates in Pi-Conjugated Oligomers and Polymers

    OpenAIRE

    2001-01-01

    We have measured the ratio, r = $\\sigma_S/\\sigma_T$ of the formation cross section, $\\sigma$ of singlet ($\\sigma_S$) and triplet ($\\sigma_T$) excitons from oppositely charged polarons in a large variety of $\\pi$-conjugated oligomer and polymer films, using the photoinduced absorption and optically detected magnetic resonance spectroscopies. The ratio r is directly related to the singlet exciton yield, which in turn determines the maximum electroluminescence quantum efficiency in organic light...

  4. Surface doping of conjugated polymers by graphene oxide and its application for organic electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yan [Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, WA 98195 (United States); State Key Laboratory of Silicon Materials, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Zhejiang-California International Nanosystems Institute, Zhejiang University, Hangzhou 310027 (China); Yip, Hin-Lap; Chen, Kung-Shih; Acton, Orb; Sun, Ying [Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, WA 98195 (United States); O' Malley, Kevin M.; Ting, Guy [Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195 (United States); Chen, Hongzheng [State Key Laboratory of Silicon Materials, MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Zhejiang-California International Nanosystems Institute, Zhejiang University, Hangzhou 310027 (China); Jen, Alex K.Y. [Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, WA 98195 (United States); Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195 (United States)

    2011-04-26

    Surface doping of conjugated polymers is realized by depositing a thin layer of graphene oxide (GO) on top of the polymers. The high proton density and the unique 2D structure of GO facilitate the protonic surface doping of conjugated polymers to achieve high conductivities. This finding represents a new strategy for improving charge transport across the metal/conjugated polymer interface to achieve much improved performance in organic solar cells. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Sequential measurements of conjugate observables

    Energy Technology Data Exchange (ETDEWEB)

    Carmeli, Claudio [Dipartimento di Fisica, Universita di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Heinosaari, Teiko [Department of Physics and Astronomy, Turku Centre for Quantum Physics, University of Turku, 20014 Turku (Finland); Toigo, Alessandro, E-mail: claudio.carmeli@gmail.com, E-mail: teiko.heinosaari@utu.fi, E-mail: alessandro.toigo@polimi.it [Dipartimento di Matematica ' Francesco Brioschi' , Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2011-07-15

    We present a unified treatment of sequential measurements of two conjugate observables. Our approach is to derive a mathematical structure theorem for all the relevant covariant instruments. As a consequence of this result, we show that every Weyl-Heisenberg covariant observable can be implemented as a sequential measurement of two conjugate observables. This method is applicable both in finite- and infinite-dimensional Hilbert spaces, therefore covering sequential spin component measurements as well as position-momentum sequential measurements.

  6. Steenrod squares on conjugation spaces

    OpenAIRE

    Franz, Matthias; Puppe, Volker

    2005-01-01

    We prove that the coefficients of the so-called conjugation equation for conjugation spaces in the sense of Hausmann-Holm-Puppe are completely determined by Steenrod squares. This generalises a result of V.A. Krasnov for certain complex algebraic varieties. It also leads to a generalisation of a formula given by Borel and Haefliger, thereby largely answering an old question of theirs in the affirmative.

  7. Determination of conjugation rates on solid surfaces

    OpenAIRE

    del Campo I.; Ruiz R; Cuevas A.; Revilla C.; Vielva L.; de la Cruz F.

    2012-01-01

    A cytometric method for the estimation of end-point conjugation rates is developed and adapted to surface conjugation. This method improves the through-put of conjugation assays based on replica-plating and results in less noisy experimental data. Although conjugation on solid surfaces deviates from ideal conditions in which cells are continuously mixed, results show that, within the limits of high initial population densities and short mating times, end-point estimates of the conjugation rat...

  8. Diversity of integrating conjugative elements in actinobacteria

    OpenAIRE

    Bordeleau, Eric; Ghinet, Mariana Gabriela; Burrus, Vincent

    2012-01-01

    Conjugation is certainly the most widespread and promiscuous mechanism of horizontal gene transfer in bacteria. During conjugation, DNA translocation across membranes of two cells forming a mating pair is mediated by two types of mobile genetic elements: conjugative plasmids and integrating conjugative elements (ICEs). The vast majority of conjugative plasmids and ICEs employ a sophisticated protein secretion apparatus called type IV secretion system to transfer to a recipient cell. Yet anoth...

  9. Investigating the Impact of Polymer Functional Groups on the Stability and Activity of Lysozyme-Polymer Conjugates.

    Science.gov (United States)

    Lucius, Melissa; Falatach, Rebecca; McGlone, Cameron; Makaroff, Katherine; Danielson, Alex; Williams, Cameron; Nix, Jay C; Konkolewicz, Dominik; Page, Richard C; Berberich, Jason A

    2016-03-14

    Polymers are often conjugated to proteins to improve stability; however, the impact of polymer chain length and functional groups on protein structure and function is not well understood. Here we use RAFT polymerization to grow polymers of different lengths and functionality from a short acrylamide oligomer with a RAFT end group conjugated to lysozyme. We show by X-ray crystallography that enzyme structure is minimally impacted by modification with the RAFT end group. Significant activity toward the negatively charged Micrococcus lysodeicticus cell wall was maintained when lysozyme was modified with cationic polymers. Thermal and chemical stability of the conjugates was characterized using differential scanning fluorimetry and tryptophan fluorescence. All conjugates had a lower melting temperature; however, conjugates containing ionic or substrate mimicking polymers were more resistant to denaturation by guanidine hydrochloride. Our results demonstrate that tailoring polymer functionality can improve conjugate activity and minimize enzymatic inactivation by denaturants. PMID:26866284

  10. The charge conjugation quantum number in multiquark systems

    OpenAIRE

    Stancu, Floarea

    2008-01-01

    Comment: 7 pages, 1 figure, based on a talk given at the Joint Meeting Heidelberg-Liege-Paris-Wroclaw (HLPW08): Three Days of Strong Interactions and Astrophysics, Spa, March 6-8, 2008, Eqs. (18)-(25) corrected, text slightly polished, conclusions unchanged

  11. High-Field-Effect Mobility of Low-Crystallinity Conjugated Polymers with Localized Aggregates.

    Science.gov (United States)

    Son, Sung Y; Kim, Yebyeol; Lee, Junwoo; Lee, Gang-Young; Park, Won-Tae; Noh, Yong-Young; Park, Chan E; Park, Taiho

    2016-07-01

    Charge carriers typically move faster in crystalline regions than in amorphous regions in conjugated polymers because polymer chains adopt a regular arrangement resulting in a high degree of π-π stacking in crystalline regions. In contrast, the random polymer chain orientation in amorphous regions hinders connectivity between conjugated backbones; thus, it hinders charge carrier delocalization. Various studies have attempted to enhance charge carrier transport by increasing crystallinity. However, these approaches are inevitably limited by the semicrystalline nature of conjugated polymers. Moreover, high-crystallinity conjugated polymers have proven inadequate for soft electronics applications because of their poor mechanical resilience. Increasing the polymer chain connectivity by forming localized aggregates via π-orbital overlap among several conjugated backbones in amorphous regions provides a more effective approach to efficient charge carrier transport. A simple strategy relying on the density of random copolymer alkyl side chains was developed to generate these localized aggregates. In this strategy, steric hindrance caused by these side chains was modulated to change their density. Interestingly, a random polymer exhibiting low alkyl side chain density and crystallinity displayed greatly enhanced field-effect mobility (1.37 cm(2)/(V·s)) compared with highly crystalline poly(3-hexylthiophene). PMID:27149835

  12. Research study of conjugate materials; Conjugate material no chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    The paper reported an introductory research on possibilities of new glass `conjugate materials.` The report took up the structure and synthetic process of conjugate materials to be researched/developed, classified them according to structural elements on molecular, nanometer and cluster levels, and introduced the structures and functions. Further, as glasses with new functions to be proposed, the paper introduced transparent and high-strength glass used for houses and vehicles, light modulation glass which realizes energy saving and optical data processing, and environmentally functional glass which realizes environmental cleaning or high performance biosensor. An initial survey was also conducted on rights of intellectual property to be taken notice of in Japan and abroad in the present situation. Reports were summed up and introduced of Osaka National Research Institute, Electrotechnical Laboratory, and National Industrial Research Institute of Nagoya which are all carrying out leading studies of conjugate materials. 235 refs., 135 figs., 6 tabs.

  13. Fractional charges

    International Nuclear Information System (INIS)

    20 years ago fractional charges were imagined to explain values of conductivity in some materials. Recent experiments have proved the existence of charges whose value is the third of the electron charge. This article presents the experimental facts that have led theorists to predict the existence of fractional charges from the motion of quasi-particles in a linear chain of poly-acetylene to the quantum Hall effect. According to the latest theories, fractional charges are neither bosons nor fermions but anyons, they are submitted to an exclusive principle that is less stringent than that for fermions. (A.C.)

  14. Polyphenol-chitosan conjugates: Synthesis, characterization, and applications.

    Science.gov (United States)

    Hu, Qiaobin; Luo, Yangchao

    2016-10-20

    Chitosan, the only positively charged polysaccharide in the world, is very attractive for food, medicinal and pharmaceutical applications because of its promising properties, including non-toxicity, superb biodegradability, high biocompatibility, abundant availability and low cost. In order to overcome the poor water solubility and widen the applications of chitosan, various polyphenol-chitosan conjugates have been synthesized in recent years. The present review focuses on the chitosan-based conjugates formed using different polyphenols, including gallic acid, caffeic acid, ferulic acid, salicylic acid, catechin, and EGGE, etc. Three major synthesis techniques, namely, activated ester-mediated modification, enzyme-mediated strategy, and free radical induced grafting approach are introduced in detail. In addition, the new physicochemical and biological properties of polyphenol-chitosan conjugates are introduced, including water solubility, thermo stability, in vitro and in vivo antioxidant activity, antimicrobial and anticancer activity. Furthermore, the novel applications of each conjugate are discussed in detail. Lastly, the challenges and prospective areas of study related to polyphenol-chitosan are summarized. PMID:27474608

  15. A Geometric View of Conjugate Priors

    CERN Document Server

    Agarwal, Arvind

    2010-01-01

    In Bayesian machine learning, conjugate priors are popular, mostly due to mathematical convenience. In this paper, we show that there are deeper reasons for choosing a conjugate prior. Specifically, we formulate the conjugate prior in the form of Bregman divergence and show that it is the inherent geometry of conjugate priors that makes them appropriate and intuitive. This geometric interpretation allows one to view the hyperparameters of conjugate priors as the {\\it effective} sample points, thus providing additional intuition. We use this geometric understanding of conjugate priors to derive the hyperparameters and expression of the prior used to couple the generative and discriminative components of a hybrid model for semi-supervised learning.

  16. Persistence Mechanisms of Conjugative Plasmids

    DEFF Research Database (Denmark)

    Bahl, Martin Iain; Hansen, Lars H.; Sørensen, Søren Johannes

    2009-01-01

    maintenance in the host cell. These importantly include the ability to self-mobilize in a process termed conjugative transfer, which may occur across species barriers. Other plasmid stabilizing mechanisms include the multimer resolution system, active partitioning, and post-segregational-killing of plasmid......Are plasmids selfish parasitic DNA molecules or an integrated part of the bacterial genome? This chapter reviews the current understanding of the persistence mechanisms of conjugative plasmids harbored by bacterial cells and populations. The diversity and intricacy of mechanisms affecting the...... successful propagation and long-term continued existence of these extra-chromosomal elements is extensive. Apart from the accessory genetic elements that may provide plasmid-harboring cells a selective advantage, special focus is placed on the mechanisms conjugative plasmids employ to ensure their stable...

  17. Big break for charge symmetry

    CERN Document Server

    Miller, G A

    2003-01-01

    Two new experiments have detected charge-symmetry breaking, the mechanism responsible for protons and neutrons having different masses. Symmetry is a crucial concept in the theories that describe the subatomic world because it has an intimate connection with the laws of conservation. The theory of the strong interaction between quarks - quantum chromodynamics - is approximately invariant under what is called charge symmetry. In other words, if we swap an up quark for a down quark, then the strong interaction will look almost the same. This symmetry is related to the concept of sup i sospin sup , and is not the same as charge conjugation (in which a particle is replaced by its antiparticle). Charge symmetry is broken by the competition between two different effects. The first is the small difference in mass between up and down quarks, which is about 200 times less than the mass of the proton. The second is their different electric charges. The up quark has a charge of +2/3 in units of the proton charge, while ...

  18. Photorefractivity in liquid crystals doped with a soluble conjugated polymer

    Science.gov (United States)

    Wiederrecht, Gary P.; Svec, Walter A.; Niemczyk, Mark P.; Wasielewski, Michael R.

    1999-10-01

    Photoconductive polymers are doped into liquid crystals to create a new mechanism for space-charge field formation in photorefractive liquid crystal composites. The composites contain poly(2,5-bis(2'-ethylhexyloxy)-1,4- phenylenevinylene) (BEH-PPV) and the electron acceptor N,N'- dioctyl-1,4:5,8-naphthalenediimide, NI. Using asymmetric energy transfer (beam coupling) measurements that are diagnostic for the photorefractive effect, the direction of beam coupling as a function of grating fringe spacing inverts at a spacing of 5.5 micrometers . We show that the inversion is due to a change in the dominant mechanism for space-charge field formation. At small fringe spacings, the space-charge field is formed by ion diffusion in which the photogenerated anion is the more mobile species. At larger fringe spacings, the polarity of the space charge field inverts due to dominance of a charge transport mechanism in which photogenerated holes are the most mobile spaces due to hole migration along the BEH-PPV chains coupled with interchain hole hopping. Control experiments are presented, which use composites that can access only one of the two charge transport mechanisms. The results show that charge migration over long distances leading to enhanced photorefractive effects can be obtained using conjugated polymers dissolved in liquid crystals.

  19. Photorefractivity in liquid crystals doped with a soluble conjugated polymer.

    Energy Technology Data Exchange (ETDEWEB)

    Niemczyk, M. P.; Svec, W. A.; Wasielewski, M. R.; Wiederrecht, G. P.

    1999-07-07

    Photoconductive polymers are doped into liquid crystals to create a new mechanism for space-charge field formation in photorefractive liquid crystal composites. The composites contain poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV) and the electron acceptor N,N{prime}-dioctyl-1,4:5,8-naphthalenediimide, NI. Using asymmetric energy transfer (beam coupling) measurements that are diagnostic for the photorefractive effect, the direction of beam coupling as a function of grating fringe spacing inverts at a spacing of 5.5 {micro}m. We show that the inversion is due to a change in the dominant mechanism for space-charge field formation. At small fringe spacings, the space-charge field is formed by ion diffusion in which the photogenerated anion is the more mobile species. At larger fringe spacings, the polarity of the space charge field inverts due to dominance of a charge transport mechanism in which photogenerated holes are the most mobile species due to hole migration along the BEH-PPV chains coupled with interchain hole hopping. Control experiments are presented, which use composites that can access only one of the two charge transport mechanisms. The results show that charge migration over long distances leading to enhanced photorefractive effects can be obtained using conjugated polymers dissolved in liquid crystals.

  20. Charged Condensation

    CERN Document Server

    Gabadadze, Gregory

    2008-01-01

    We consider Bose-Einstein condensation of massive electrically charged scalars in a uniform background of charged fermions. We focus on the case when the scalar condensate screens the background charge, while the net charge of the system resides on its boundary surface. A distinctive signature of this substance is that the photon acquires a Lorentz-violating mass in the bulk of the condensate. Due to this mass, the transverse and longitudinal gauge modes propagate with different group velocities. We give qualitative arguments that at high enough densities and low temperatures a charged system of electrons and helium-4 nuclei, if held together by laboratory devices or by force of gravity, can form such a substance. We briefly discuss possible manifestations of the charged condensate in compact astrophysical objects.

  1. Mappings of Conjugation of Quaternion Algebra

    OpenAIRE

    Kleyn, Aleks

    2012-01-01

    In the paper I considered mappings of conjugation of quaternion algebra. I proved the theorem that there is unique expansion of R-linear mapping of quaternion algebra relative to the given set of mappings of conjugation.

  2. Recent Advances in Boron-Containing Conjugated Porous Polymers

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2016-05-01

    Full Text Available Porous polymers, integrating the advantages of porous materials and conventional polymers, have been well developed and exhibited tremendous attention in the fields of material, chemistry and biology. Of these, boron-containing conjugated porous polymers, featuring tunable geometric structures, unique Lewis acid boron centers and very rich physical properties, such as high specific surface, chargeable scaffold, strong photoluminescence and intramolecular charge transfer, have emerged as one of the most promising functional materials for optoelectronics, catalysis and sensing, etc. Furthermore, upon thermal treatment, some of them can be effectively converted to boron-doped porous carbon materials with good electrochemical performance in energy storage and conversion, extensively enlarging the applicable scope of such kinds of polymers. In this review, the synthetic approaches, structure analyses and various applications of the boron-containing conjugated porous polymers reported very recently are summarized.

  3. Advanced conjugated polymers for photonics

    Czech Academy of Sciences Publication Activity Database

    Cimrová, Věra; Výprachtický, Drahomír; Kmínek, Ivan; Dzhabarov, Vagif; Pokorná, Veronika

    Orlando, 2013. s. 142. [2013 EMN Fall - 2013 Energy Materials & Nanotechnology Meeting. 07.12.2013-10.12.2013, Orlando] R&D Projects: GA ČR(CZ) GA13-26542S; GA ČR GAP106/12/0827 Institutional support: RVO:61389013 Keywords : conjugated polymers * photoluminescence * electroluminescence Subject RIV: CD - Macromolecular Chemistry

  4. Peptide-LNA oligonucleotide conjugates

    DEFF Research Database (Denmark)

    Astakhova, I Kira; Hansen, Lykke Haastrup; Vester, Birte; Wengel, Jesper

    2013-01-01

    Although peptide-oligonucleotide conjugates (POCs) are well-known for nucleic acids delivery and therapy, reports on internal attachment of peptides to oligonucleotides are limited in number. To develop a convenient route for preparation of internally labeled POCs with improved biomedical...

  5. Glutathione conjugation as a bioactivation reaction

    NARCIS (Netherlands)

    Bladeren, P.J. van

    2000-01-01

    In general, glutathione conjugation is regarded as a detoxication reaction. However, depending on the properties of the substrate, bioactivation is also possible. Four types of activation reaction have been recognized: direct-acting compounds, conjugates that are activated through cysteine conjugate

  6. Conjugation of Morse Function on 3-Manifolds

    OpenAIRE

    Prishlyak, Alexander

    1998-01-01

    The questions when two Morse function on closed manifolds are conjugated is investigated. Using the handle decompositions of manifolds the condition of conjugation is formulated. For each Morse function on 3-manifold the ordered generalized Heegaard diagram is built. The criteria of Morse function conjugation are given in the terms of equivalence of such diagrams.

  7. Tuning the Electron Acceptor in Phthalocyanine-Based Electron Donor-Acceptor Conjugates.

    Science.gov (United States)

    Sekita, Michael; Jiménez, Ángel J; Marcos, M Luisa; Caballero, Esmeralda; Rodríguez-Morgade, M Salomé; Guldi, Dirk M; Torres, Tomás

    2015-12-21

    Zinc phthalocyanines (ZnPc) have been attached to the peri-position of a perylenemonoimide (PMI) and a perylenemonoanhydride (PMA), affording electron donor-acceptor conjugates 1 and 2, respectively. In addition, a perylene-monoimide-monoanhydride (PMIMA) has been connected to a ZnPc through its imido position to yield the ZnPc-PMIMA conjugate 10. The three conjugates have been studied for photoinduced electron transfer. For ZnPc-PMIMA 10, electron transfer occurs upon both ZnPc and PMIMA excitation, giving rise to a long-lived (340 ps) charge-separated state. For ZnPc-PMI 1 and ZnPc-PMA 2, stabilization of the radical ion pair states by using polar media is necessary. In THF, photoexcitation of either ZnPc or PMI/PMA produces charge-separated states with lifetimes of 375 and 163 ps, respectively. PMID:26593778

  8. Purification of SUMO conjugating enzymes and kinetic analysis of substrate conjugation

    OpenAIRE

    Yunus, Ali A.; Lima, Christopher D.

    2009-01-01

    SUMO conjugation to protein substrates requires the concerted action of a dedicated E2 ubiquitin conjugation enzyme (Ubc9) and associated E3 ligases. Although Ubc9 can directly recognize and modify substrate lysine residues that occur within a consensus site for SUMO modification, E3 ligases can redirect specificity and enhance conjugation rates during SUMO conjugation in vitro and in vivo. In this chapter, we will describe methods utilized to purify SUMO conjugating enzymes and model substra...

  9. Low-Dimensional Conduction Mechanisms in Highly-Conductive and Transparent Conjugated Polymers

    OpenAIRE

    Ugur Katmis, Asli; Katmis, Ferhat; Li, Mingda; Wu, Lijun; Varanasi, Kripa K.; Gleason, Karen K.; Zhu, Yimei

    2015-01-01

    Electronic conduction in conjugated polymers is of emerging technological interest for high-performance optoelectronic and thermoelectric devices. A completely new aspect and understanding of the conduction mechanism on conducting polymers is introduced, allowing the applicability of materials to be optimized. The charge-transport mechanism is explained by direct experimental evidence with a very well supported theoretical model.

  10. Low-Dimensional Conduction Mechanisms in Highly Conductive and Transparent Conjugated Polymers

    OpenAIRE

    Ugur, Asli; Katmis, Ferhat; Li, Mingda; Wu, Lijun; Zhu, Yimei; Varanasi, Kripa K.; Gleason, Karen K.

    2015-01-01

    Electronic conduction in conjugated polymers is of emerging technological interest for high-performance optoelectronic and thermoelectric devices. A completely new aspect and understanding of the conduction mechanism on conducting polymers is introduced, allowing the applicability of materials to be optimized. The charge-transport mechanism is explained by direct experimental evidence with a very well supported theoretical model.

  11. Conjugative plasmids of Neisseria gonorrhoeae.

    Directory of Open Access Journals (Sweden)

    Emilia Pachulec

    Full Text Available Many clinical isolates of the human pathogen Neisseria gonorrhoeae contain conjugative plasmids. The host range of these plasmids is limited to Neisseria species, but presence of a tetracycline (tetM determinant inserted in several of these plasmids is an important cause of the rapid spread of tetracycline resistance. Previously plasmids with different backbones (Dutch and American type backbones and with and without different tetM determinants (Dutch and American type tetM determinants have been identified. Within the isolates tested, all plasmids with American or Dutch type tetM determinants contained a Dutch type plasmid backbone. This demonstrated that tetM determinants should not be used to differentiate between conjugal plasmid backbones. The nucleotide sequences of conjugative plasmids with Dutch type plasmid backbones either not containing the tetM determinant (pEP5233 or containing Dutch (pEP5289 or American (pEP5050 type tetM determinants were determined. Analysis of the backbone sequences showed that they belong to a novel IncP1 subfamily divergent from the IncP1alpha, beta, gamma, delta and epsilon subfamilies. The tetM determinants were inserted in a genetic load region found in all these plasmids. Insertion was accompanied by the insertion of a gene with an unknown function, and rearrangement of a toxin/antitoxin gene cluster. The genetic load region contains two toxin/antitoxins of the Zeta/Epsilon toxin/antitoxin family previously only found in Gram positive organisms and the virulence associated protein D of the VapD/VapX toxin/antitoxin family. Remarkably, presence of VapX of pJD1, a small cryptic neisserial plasmid, in the acceptor strain strongly increased the conjugation efficiency, suggesting that it functions as an antitoxin for the conjugative plasmid. The presence of the toxin and antitoxin on different plasmids might explain why the host range of this IncP1 plasmid is limited to Neisseria species. The isolated plasmids

  12. Charge transport in conducting polymers

    International Nuclear Information System (INIS)

    Polymers with metal-like electrical conductivity are presented as novel materials. After a short discussion of the present situation of technical applications experimental data on the electrical conductivity and its temperature and frequency dependence are reviewed. These data are discussed within the framework of a model involving fluctuation-induced tunneling between marcroscopic inhomogeneities and energy dependent hopping of charge carriers between localized states on a microscopic level. Pulsed photoconductivity measurements indicate that also in photoconductivity a hopping mechanism is dominant and solitary wave motion of conjugational defects escapes observation. (orig.)

  13. Charge independence and charge symmetry

    CERN Document Server

    Miller, G A; Miller, Gerald A; van Oers, Willem T H

    1994-01-01

    Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed.

  14. Charge independence and charge symmetry

    International Nuclear Information System (INIS)

    Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed. (author). 145 refs., 3 tabs., 11 figs

  15. Synthesis and study of conjugated polymers containing Di- or Triphenylamine

    Energy Technology Data Exchange (ETDEWEB)

    Sukwattanasinitt, M.

    1996-06-21

    This thesis consists of two separate parts. The first part addresses the synthesis and study of conjugated polymers containing di- or triphenylamine. Two types of polymers: linear polymers and dendrimers, were synthesized. The polymers were characterized by NMR, IR, UV, GPC, TGA and DSC. Electronic and optical properties of the polymers were studied through the conductivity measurements and excitation- emission spectra. the second part of this thesis deals with a reaction of electron-rich acetylenes with TCNE. The discovery of the reaction from charge transfer complex studies and the investigation of this reaction on various electron-rich acetylenes are presented.

  16. Organometallic B12-DNA conjugate

    DEFF Research Database (Denmark)

    Hunger, Miriam; Mutti, Elena; Rieder, Alexander;

    2014-01-01

    humans and animals, through the endogenous B12 transport systems. Binding of the organometallic B12 octadecanucleotide to the three important human proteins of B12 transport was studied, to examine its structural suitability for the task of eventual in vivo oligonucleotide delivery. Binding was efficient......Design, synthesis, and structural characterization of a B12-octadecanucleotide are presented herein, a new organometallic B12-DNA conjugate. In such covalent conjugates, the natural B12 moiety may be a versatile vector for controlled in vivo delivery of oligonucleotides to cellular targets in...... with transcobalamin (TC), but not so efficient with the homologous glycoproteins intrinsic factor and haptocorrin. Binding of the B12 octadecanucleotide to TC suggests the capacity of the B12 moiety to serve as a natural vector for specific transport of single stranded, organometallic oligonucleotide...

  17. The ISG15 conjugation system.

    Science.gov (United States)

    Durfee, Larissa A; Huibregtse, Jon M

    2012-01-01

    ISG15 is a ubiquitin-like modifier that is expressed in response to type 1 interferon signaling (IFN-α/β) and plays a role in antiviral responses. The core E1, E2, and E3 enzymes for ISG15 are Ube1L, UbcH8, and Herc5, respectively, and these are all also induced at the transcriptional level by IFN-α/β. We recently showed that Herc5 associates with polysomes and modifies target proteins in a cotranslational manner. Here, we describe the expression of the core conjugating enzymes in human cells, the detection of ISG15 conjugates, and the methods for fractionation of Herc5 with polysomes. PMID:22350882

  18. Conjugated Polymers for Energy Production

    DEFF Research Database (Denmark)

    Livi, Francesco

    This dissertation is aimed at developing materials for flexible, large area, ITO-free polymer solar cells (PSCs) fully printed under ambient conditions. A large screening of conjugated polymers, both novel and well-known materials, has been carried out in order to find suitable candidates...... for scalable PSCs fully printed under ambient conditions [Adv. Energy Mater. 2015, 5, 1402186]. PPDTBT resulted to be the conjugated polymer with the best photovoltaic performance within the 104 synthesized macromolecules. Therefore, further studies have been done on such material. The impact of side chain...... arylation (DAr) and direct arylation polymerization (DArP) have been applied to the preparation of PPDTBT, making this polymer readily available in only 4 synthetic steps and thus easily transferable to a large scale-production setup. DArP avoids organometallic species and therefore is an appealing...

  19. Fiber bundle phase conjugate mirror

    Science.gov (United States)

    Ward, Benjamin G.

    2012-05-01

    An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

  20. Conjugated polyelectrolytes fundamentals and applications

    CERN Document Server

    Liu, Bin

    2013-01-01

    This is the first monograph to specifically focus on fundamentals and applications of polyelectrolytes, a class of molecules that gained substantial interest due to their unique combination of properties. Combining both features of organic semiconductors and polyelectrolytes, they offer a broad field for fundamental research as well as applications to analytical chemistry, optical imaging, and opto-electronic devices. The initial chapters introduce readers to the synthesis, optical and electrical properties of various conjugated polyelectrolytes. This is followed by chapters on the applica

  1. Variable metric conjugate gradient methods

    Energy Technology Data Exchange (ETDEWEB)

    Barth, T.; Manteuffel, T.

    1994-07-01

    1.1 Motivation. In this paper we present a framework that includes many well known iterative methods for the solution of nonsymmetric linear systems of equations, Ax = b. Section 2 begins with a brief review of the conjugate gradient method. Next, we describe a broader class of methods, known as projection methods, to which the conjugate gradient (CG) method and most conjugate gradient-like methods belong. The concept of a method having either a fixed or a variable metric is introduced. Methods that have a metric are referred to as either fixed or variable metric methods. Some relationships between projection methods and fixed (variable) metric methods are discussed. The main emphasis of the remainder of this paper is on variable metric methods. In Section 3 we show how the biconjugate gradient (BCG), and the quasi-minimal residual (QMR) methods fit into this framework as variable metric methods. By modifying the underlying Lanczos biorthogonalization process used in the implementation of BCG and QMR, we obtain other variable metric methods. These, we refer to as generalizations of BCG and QMR.

  2. Charged Leptons

    CERN Document Server

    Albrecht, J; Babu, K; Bernstein, R H; Blum, T; Brown, D N; Casey, B C K; Cheng, C -h; Cirigliano, V; Cohen, A; Deshpande, A; Dukes, E C; Echenard, B; Gaponenko, A; Glenzinski, D; Gonzalez-Alonso, M; Grancagnolo, F; Grossman, Y; Harnik, R; Hitlin, D G; Kiburg, B; Knoepfe, K; Kumar, K; Lim, G; Lu, Z -T; McKeen, D; Miller, J P; Ramsey-Musolf, M; Ray, R; Roberts, B L; Rominsky, M; Semertzidis, Y; Stoeckinger, D; Talman, R; Van De Water, R; Winter, P

    2013-01-01

    This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

  3. ON CONJUGATES AND MODULII OF BICOMPLEX NUMBERS

    Directory of Open Access Journals (Sweden)

    JAISHREE

    2012-06-01

    Full Text Available The paper presents extensive use of complex pairs to develop the algebraic properties of bicomplex numbers and contains various aspects of finding the conjugates and modulii of bicomplex numbers.We discuss three types of conjugations and some specific modulii with complex and hyperbolic ranges. We also examine the impact of different conjugations on the principal ideals I1 and I2.

  4. Phase Conjugation of Continuous Quantum Variables

    OpenAIRE

    Cerf, N. J.; Iblisdir, S.

    2000-01-01

    The phase conjugation of an unknown Gaussian state cannot be realized perfectly by any physical process. A semi-classical argument is used to derive a tight lower bound on the noise that must be introduced by an approximate phase conjugation operation. A universal transformation achieving the optimal imperfect phase conjugation is then presented, which is the continuous counterpart of the universal-NOT transformation for quantum bits. As a consequence, it is also shown that more information c...

  5. Haptens, conjugates and antibodies for pyrimethanil fungicide

    OpenAIRE

    Mercader Badia, Josep Vicent; Abad Fuentes, Antonio; Abad Somovilla, Antonio; Agulló, Consuelo

    2012-01-01

    [EN] The invention relates to haptens, conjugates and antibodies for pyrimethanil fungicide. In addition, the invention relates to the use of pyrimethanil conjugates as assay antigens or immunogens in order to obtain antibodies of the aforementioned fungicide, and to the use of the labelled derivatives of pyrimethanil as assay antigens. The invention also relates to a pyrimethanil analysis method using the antibodies obtained, at times together with assay antigens which are conjugates or labe...

  6. Modelling conjugation with stochastic differential equations

    DEFF Research Database (Denmark)

    Philipsen, Kirsten Riber; Christiansen, Lasse Engbo; Hasman, Henrik;

    2010-01-01

    Conjugation is an important mechanism involved in the transfer of resistance between bacteria. In this article a stochastic differential equation based model consisting of a continuous time state equation and a discrete time measurement equation is introduced to model growth and conjugation of two...... using a likelihood-ratio test and Akaike's information criterion. Experiments indicating conjugation on the agar plates selecting for transconjugants motivates the introduction of an extended model, for which conjugation on the agar plate is described in the measurement equation. This model is compared...

  7. Nanoparticles of Fluorescent Conjugated Polymers: Novel Ion-Selective Optodes.

    Science.gov (United States)

    Kłucińska, Katarzyna; Stelmach, Emilia; Kisiel, Anna; Maksymiuk, Krzysztof; Michalska, Agata

    2016-06-01

    A novel type of ion-selective nano-optode is proposed, in which a conjugated polymer is used as optical transducer and nanoprobe material. Thus, contrary to most of the proposed optodes, the response does not require presence of pH-sensitive dye in the sensor. The conjugated polymer nanosensor material is in partially oxidized form-it is bearing positive charges and its emission is quenched. The receptor is an optically silent uncharged ionophore selective for the analyte cation. When a binding event occurs, positive charges are formed in the nanosphere, leading to a decrease in the oxidation state of the polymer, in the absence of redox potential change, resulting in increased emission. This general approach herein proposed results in a simple sensor, benefitting from a novel optical transduction mechanism and high lipophilicity of the polymer matrix that results in linear responses over a broad concentration range of analyte. For the model system studied, the linear dependence of emission intensity on the logarithm of analyte (K(+)) concentration was obtained for a broad range from 10(-5) M to 0.1 M. PMID:27136386

  8. Separation efficiency of free-solution conjugated electrophoresis with drag-tags incorporating a synthetic amino acid.

    Science.gov (United States)

    Seo, Kyung-Ho; Chu, Hun-Su; Yoo, Tae Hyeon; Lee, Sun-Gu; Won, Jong-In

    2016-03-01

    DNA sequencing or separation by conventional capillary electrophoresis with a polymer matrix has some inherent drawbacks, such as the expense of polymer matrix and limitations in sequencing read length. As DNA fragments have a linear charge-to-friction ratio in free solution, DNA fragments cannot be separated by size. However, size-based separation of DNA is possible in free-solution conjugate electrophoresis (FSCE) if a "drag-tag" is attached to DNA fragments because the tag breaks the linear charge-to-friction scaling. Although several previous studies have demonstrated the feasibility of DNA separation by free-solution conjugated electrophoresis, generation of a monodisperse drag-tag and identification of a strong, site-specific conjugation method between a DNA fragment and a drag-tag are challenges that still remain. In this study, we demonstrate an efficient FSCE method by conjugating a biologically synthesized elastin-like polypeptide (ELP) and green fluorescent protein (GFP) to DNA fragments. In addition, to produce strong and site-specific conjugation, a methionine residue in drag-tags is replaced with homopropargylglycine (Hpg), which can be conjugated specifically to a DNA fragment with an azide site. PMID:26757485

  9. DENDRIMER CONJUGATES FOR SELECTIVE OF PROTEIN AGGREGATES

    DEFF Research Database (Denmark)

    2004-01-01

    Dendrimer conjugates are presented, which are formed between a dendrimer and a protein solubilising substance. Such dendrimer conjugates are effective in the treatment of protein aggregate-related diseases (e.g. prion-related diseases). The protein solubilising substance and the dendrimer together...

  10. CONJUGATE-SYMPLECTICITY OF LINEAR MULTISTEP METHODS

    Institute of Scientific and Technical Information of China (English)

    Ernst Hairer

    2008-01-01

    For the numerical treatment of Hamiltonian differential equations, symplectic integra-tors are the most suitable choice, and methods that are conjugate to a symplectic integrator share the same good long-time behavior. This note characterizes linear multistep methods whose underlying one-step method is conjugate to a symplectic integrator. The bounded-hess of parasitic solution components is not addressed.

  11. Multicolor passive (self-pumped) phase conjugation

    OpenAIRE

    Cronin-Golomb, Mark; Kwong, Sze-Keung; Yariv, Amnon

    1984-01-01

    Passive phase conjugation of up to six lines (457, 476, 488, 496, 501, and 514 nm) of the all lines output of an argon ion laser is reported. Imaging characteristics and reflectivity measurements are given. In general, multiline operation results in some loss in both reflectivity and image resolution. This work opens the possibility for passive phase conjugation of full color images.

  12. Studies on conjugation of Spirogyra using monoclonal culture

    OpenAIRE

    Ikegaya, Hisato; Nakase, Takuto; Iwata, Kazuyoshi; Tsuchida, Hideaki; Sonobe, Seiji; Shimmen, Teruo

    2011-01-01

    We succeeded in inducing conjugation of Spirogyra castanacea by incubating algal filaments on agar plate. Conjugation could be induced using clone culture. The scalariform conjugation was generally observed, while lateral conjugation was rarely. When two filaments formed scalariform conjugation, all cells of one filament behaved as male and those of other filament did as female. Very rarely, however, zygospores were formed in both of pair filaments. The surface of conjugation tube was stained...

  13. Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

    Institute of Scientific and Technical Information of China (English)

    Xueke Ding; Jian Rong; Hong Bai; Xiu Wang; Jine Shen; Fang Li

    2008-01-01

    A multi-conjugate adaptive optics (MCAO) can offer a possibility of widening field of view (FOV) characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO,which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle's expressions of two deformable mirrors (DMs) MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.

  14. Approximate error conjugation gradient minimization methods

    Science.gov (United States)

    Kallman, Jeffrey S

    2013-05-21

    In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.

  15. Enzyme- and pH-Sensitive Branched Polymer-Doxorubicin Conjugate-Based Nanoscale Drug Delivery System for Cancer Therapy.

    Science.gov (United States)

    Wei, Xiaoli; Luo, Qiang; Sun, Ling; Li, Xue; Zhu, Hongyan; Guan, Pujun; Wu, Min; Luo, Kui; Gong, Qiyong

    2016-05-11

    Owing to their dendritic architectural features, branched copolymers have been investigated as drug delivery systems. In this paper, an enzyme- and pH-sensitive branched poly[N-(2-hydroxypropyl)methacrylamide] (polyHPMA) copolymer-doxorubicin (DOX) conjugate possessing a molecular weight (MW) of 165 kDa was designed and prepared via a one-pot reaction and drug conjugation. This conjugate's potential as a smart, nanoscale drug delivery system (NDDS) is also investigated. The branched conjugate was capable of forming nanoparticles with a negative surface charge. The self-assembled nanoparticles were 102 nm in diameter as measured by dynamic light scattering (DLS) and 95 nm in diameter via scanning electron microscopy, respectively. The nanoparticles were degraded to low-MW products (23∼25 kDa) in the presence of papain or cathepsin B, and the degradation was monitored via DLS and size-exclusion chromatography. The nanoparticles demonstrated pH-sensitive drug release, as the DOX was attached to the branched copolymer via a hydrazone bond. In comparison to free DOX, the conjugate-based nanoparticles exhibited greater accumulation in breast tumors, resulting in enhanced antitumor therapeutic indexes. Furthermore, widespread dissemination of the conjugate among breast tumor cells was confirmed by immunohistochemical assay. Finally, no obvious systemic toxicities were observed in vivo in normal mice. Thus, the branched HPMA copolymer-DOX conjugate may be employed as a safe and efficient pH- and enzyme-responsive NDDS for cancer therapy. PMID:27102364

  16. Conjugated Polymer Surfaces and Interfaces

    Science.gov (United States)

    Salaneck, W. R.; Stafstrom, S.; Brédas, J. L.

    2003-10-01

    The authors illustrate the basic physics and materials science of conjugated polymers and their interfaces, particularly, but not exclusively, as they are applied to polymer-based light emitting diodes. The approach is to describe the basic physical and associated chemical principles that apply to these materials, which in many instances are different from those that apply to their inorganic counterparts. The main aim of the authors is to highlight specific issues and properties of polymer surfaces and interfaces that are relevant in the context of the emerging field of polymer-based electronics in general, and polymer-based light emitting diodes in particular. Both theoretical and experimental methods used in the study of these systems are discussed. This book will be of interest to graduate students and research workers in departments of physics, chemistry, electrical engineering and materials sciences studying polymer surfaces and interfaces and their application in polymer-based electronics.

  17. Novel conjugates of peptides and conjugated polymers for optoelectronics and neural interfaces

    Science.gov (United States)

    Bhagwat, Nandita

    Peptide-polymer conjugates are a novel class of hybrid materials that take advantage of each individual component giving the opportunity to generate materials with unique physical, chemical, mechanical, optical, and electronic properties. In this dissertation peptide-polymer conjugates for two different applications are discussed. The first set of peptide-polymer conjugates were developed as templates to study the intermolecular interactions between electroactive molecules by manipulating the intermolecular distances at nano-scale level. A PEGylated, alpha-helical peptide template was employed to effectively display an array of organic chromophores (oxadiazole containing phenylenevinylene oligomers, Oxa-PPV). Three Oxa-PPV chromophores were strategically positioned on each template, at distances ranging from 6 to 17 A from each other, as dictated by the chemical and structural properties of the peptide. The Oxa-PPV modified PEGylated helical peptides (produced via Heck coupling strategies) were characterized by a variety of spectroscopic methods. Electronic contributions from multiple pairs of chromophores on a scaffold were detectable; the number and relative positioning of the chromophores dictated the absorbance and emission maxima, thus confirming the utility of these polymer--peptide templates for complex presentation of organic chromophores. The rest of the thesis is focused on using poly(3,4-alkylenedioxythiophene) based conjugated polymers as coatings for neural electrodes. This thiophene derivative is of considerable current interest for functionalizing the surfaces of a wide variety of devices including implantable biomedical electronics, specifically neural bio-electrodes. Toward these ends, copolymer films of 3,4-ethylenedioxythiophene (EDOT) with a carboxylic acid functional EDOT (EDOTacid) were electrochemically deposited and characterized as a systematic function of the EDOTacid content (0, 25, 50, 75, and 100%). The chemical surface characterization

  18. Physicochemical Characterization and Cytotoxicity Screening of a Novel Colloidal Nanogold-Based Phenytoin Conjugate

    Science.gov (United States)

    Suneetha, Susan Cleave A; Raghupathy, Bala Praveen Chakkravarthy; Suresh, P. K.

    2014-01-01

    Abstract A novel, colloidal nanogold-based drug delivery system for phenytoin, a well-known anti-epileptic drug with an enhanced efflux via P-glycoprotein, has been proposed in this study. The vital physical properties that would aid in predicting the biological interaction of this system were profiled using various techniques such as UV-Vis, DLS, and TEM in corroboration with theoretical calculations. It was significant to note that the binding of phenytoin to colloidal nanogold was strongly pH-dependent with the optimum at pH 5.5 and a consistently reproducible spectral shift. Analysis of the conjugate by FTIR revealed that the imide functional group of phenytoin mediated a dative coordinate bond to colloidal nanogold at the optimum pH. The amount of the drug bound to the gold was quantified to be 85.8±2.5% (w/v) by HPLC. Hypothetically, the surface charge of the conjugate could possibly imply charge-mediated uptake across the cell membrane. Further, the novel conjugate was screened for its cytotoxicity in two cell lines and the dosage range was identified. Subsequent development, thorough evaluations in suitable model systems, and the potential for bioimaging to track the payload would validate our hypothesis on the conjugate for better intracellular retention at the site of action, and thereby achieve the targeted delivery. PMID:26171330

  19. Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes.

    Science.gov (United States)

    Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

    2016-01-01

    Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application. PMID:26931282

  20. π-Conjugated Donor-Acceptor Systems as Metal-Free Sensitizers for Dye-Sensitized Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Zakeeruddin S. M.

    2013-03-01

    Full Text Available High extinction coefficients and easily tunable spectral properties of π- conjugated donor-acceptor dyes are of superior advantage for the design of new metalfree organic sensitizers for applications in dye-sensitized solar cells. Ultrafast transient absorption spectroscopy on the femtosecond and nanosecond time scales provided deep insights into the dependence of charge carrier dynamics in fully organic dye/TiO2 systems on i the donor-acceptor distance, ii the π-conjugation length, and iii the coupling to TiO2 by different anchoring groups. Importantly, the observed differences in charge transfer dynamics justify the variations of photovoltaic performances of the dyes as applied in solar cell devices. This leads to the conclusion that the photoconversion efficiencies strongly depend on a delicate interplay between the dyes’ building blocks, i.e. the donor, the π-conjugated spacer and the anchor/acceptor moieties, and may easily be tuned by molecular design.

  1. Nanostructured Conjugated Polymers for Energy-Related Applications beyond Solar Cells.

    Science.gov (United States)

    Xie, Jian; Zhao, Cui-E; Lin, Zong-Qiong; Gu, Pei-Yang; Zhang, Qichun

    2016-05-20

    To meet the ever-increasing requirements for the next generation of sustainable and versatile energy-related devices, conjugated polymers, which have potential advantages over small molecules and inorganic materials, are among the most promising types of green candidates. The properties of conjugated polymers can be tuned through modification of the structure and incorporation of different functional moieties. In addition, superior performances can be achieved as a result of the advantages of nanostructures, such as their large surface areas and the shortened pathways for charge transfer. Therefore, nanostructured conjugated polymers with different properties can be obtained to be applied in different energy-related organic devices. This review focuses on the application and performance of the recently reported nanostructured conjugated polymers for high-performance devices, including rechargeable lithium batteries, microbial fuel cells (MFCs), thermoelectric generators, and photocatalytic systems. The design strategies, reaction mechanisms, advantages, and limitations of nanostructured conjugated polymers are further discussed in each section. Finally, possible routes to improve the performances of the current systems are also included in the conclusion. PMID:26971875

  2. Cationic conjugated polymers for homogeneous and sensitive fluorescence detection of hyaluronidase

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The cationic charged water-soluble polyfluorenes containing 2,1,3-benzothiadiazole (BT) units (P1-3) have been synthesized and characterized. These polymers demonstrate intramolecular energy transfer from the fluorene units to the BT sites when oppositely charged hyaluronan is added due to the formation of electrostatic complexes, followed by a shift in emission color from blue to green or brown. Upon adding hyaluronidase, the hyaluronan is cleaved into fragments. The relatively weak electrostatic interactions of hyaluronan fragments with polyfluorenes keep their main chains separated and energy transfer from the fluorene units to the BT sites is inefficient, and the polyfluorenes recover their blue emissions. The complexes of conjugated polymers/hyaluronan can be utilized as probes for sensitive and facile fluorescence assays for hyaluronidase. The new assay method interfaces with the aggregation and light harvesting properties of conjugated polymers.

  3. Cationic conjugated polymers for homogeneous and sensitive fluorescence detection of hyaluronidase

    Institute of Scientific and Technical Information of China (English)

    AN LingLing; LIU LiBing; WANG Shu

    2009-01-01

    The cationic charged water-soluble polyfluorenee containing 2,1,3-benzothiadiazole (BT) units (P1--3) have been synthesized and characterized. These polymers demonstrate intramolecular energy transfer from the fluorene units to the BT sites when oppositely charged hyaluronan is added due to the forma-tion of electrostatic complexes, followed by a shift in emission color from blue to green or brown. Upon adding hyaluronidaee, the hyaluronan is cleaved into fragments. The relatively weak electrostatic in-teractions of hyaluronan fragments with polyfluorenes keep their main chains separated and energy transfer from the fluorene units to the BT sites is inefficient, and the polyfluorenes recover their blue emissions. The complexes of conjugated polymers/hyaluronan can be utilized as probes for sensitive and facile fluorescence assays for hyaluronidase. The new assay method interfaces with the aggrega-tion and light harvesting properties of conjugated polymers.

  4. Photoinduced electron transfer in a Watson-Crick base-paired, 2-aminopurine:uracil-C60 hydrogen bonding conjugate.

    Science.gov (United States)

    D'Souza, Francis; Gadde, Suresh; Islam, D-M Shafiqul; Pang, Siew-Cheng; Schumacher, Amy Lea; Zandler, Melvin E; Horie, Rumiko; Araki, Yasuyaki; Ito, Osamu

    2007-02-01

    A fluorescent reporter molecule, 2-aminopurine was self-assembled via Watson-Crick base-pairing to a uracil appended fullerene to form a donor-acceptor conjugate; efficient photoinduced charge separation was confirmed by time-resolved emission and transient absorption spectral studies. PMID:17252101

  5. Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

    DEFF Research Database (Denmark)

    Chang, J.F.; Clark, J.; Zhao, N.;

    2006-01-01

    Interchain interactions have a profound effect on the optical as well as charge transport properties of conjugated polymer thin films. In contrast to oligomeric model systems in solution-deposited polymer thin films the study of such effects is complicated by the complex microstructure. We presen...

  6. Xenobiotic conjugation with phosphate - a metabolic rarity.

    Science.gov (United States)

    Mitchell, Stephen C

    2016-08-01

    1. Although not unknown, the conjugation of a xenobiotic with phosphate appears a rarity amongst the routes available for foreign compound metabolism. This is especially true in mammals and may be somewhat surprising as conjugation with sulphate, a seemingly similar moiety, is commonplace. 2. Information from the literature, where xenobiotic phosphate conjugates have been described or suggested, has been collated and presented in this article. By bringing together this diverse material, hopefully interest will be generated in this unusual xenobiotic reaction, and perhaps further research undertaken to better understand and delineate the reasons for its relative absence from the xenobiotic scene. PMID:26611118

  7. Mitigation of nonlinearities using conjugate data repetition.

    Science.gov (United States)

    Eliasson, Henrik; Johannisson, Pontus; Karlsson, Magnus; Andrekson, Peter A

    2015-02-01

    We investigate a time-domain implementation of generalized phase-conjugated twin waves which we call conjugate data repetition. A theory based on time-domain perturbation analysis explaining the mitigation of nonlinear effects is provided, and the concept is evaluated using numerical simulations. Compared to PM-QPSK at the same channel bit rate, the single-channel transmission reach in a conventional system with standard single-mode fiber of conjugate data repetition-QPSK is increased by approximately a factor of 2. PMID:25836107

  8. Modelling the size-dependence effects on the electronic properties of conjugated oligomers

    OpenAIRE

    Correia, Helena M. G.; Ramos, Marta M. D.

    2011-01-01

    Comunicação oral. Conjugated oligomers are materials that have the potential to be used in organic and hybrid electronic and optoelectronic devices as an active component. However, the electronic properties responsible for their electrical and optical behaviour are size-dependent. Here we use a self-consistent quantum molecular dynamics method to study the effect of the oligomers length at nanosize regime on the ionization potential, electron affinity, charge (electrons and holes) mobility...

  9. Marriage of heavy main group elements with π-conjugated materials for optoelectronic applications.

    Science.gov (United States)

    Parke, Sarah M; Boone, Michael P; Rivard, Eric

    2016-08-01

    This review article summarizes recent progress in the synthesis and optoelectronic properties of conjugated materials containing heavy main group elements from Group 13-16 as integral components. As will be discussed, the introduction of these elements can promote novel phosphorescent behavior and support desirable molecular and polymeric properties such as low optical band gaps and high charge mobilities for photovoltaic and thin film transistor applications. PMID:27344980

  10. Electrical properties of doped conjugated polyelectrolytes with modulated density of the ionic functionalities.

    Science.gov (United States)

    Mai, Cheng-Kang; Arai, Tomoya; Liu, Xiaofeng; Fronk, Stephanie L; Su, Gregory M; Segalman, Rachel A; Chabinyc, Michael L; Bazan, Guillermo C

    2015-12-25

    We report the synthesis of a series of water-soluble anionic narrow band-gap conjugated polyelectrolytes with a varied density of the ionic functional groups. The charge density is modulated by incorporating the structural units with tetraethylene glycol (TEG) monomethyl ether side chains. These polymers are readily p-doped during dialysis in water. CPEs with TEG side chains exhibit tighter intermolecular packing in the solid state and higher electrical conductivity. PMID:26483359

  11. Energetics of Excited States in the Conjugated Polymer Poly(3-hexylthiophene)

    OpenAIRE

    Deibel, Carsten; Mack, Daniel; Gorenflot, Julien; Schoell, Achim; Krause, Stefan; Reinert, Friedrich; Rauh, Daniel; Dyakonov, Vladimir

    2010-01-01

    There is an enormous potential in applying conjugated polymers in novel organic opto-electronic devices such as light emitting diodes and solar cells. Although prototypes and first products exist, a comprehensive understanding of the fundamental processes and energetics involved during photoexcitation is still lacking and limits further device optimisations. Here we report on a unique analysis of the excited states involved in charge generation by photoexcitation. On the model system poly(3-h...

  12. Effect of Spacer Connecting the Secondary Electron Donor Phenothiazine in Subphthalocyanine-Fullerene Conjugates in Promoting Electron Transfer Followed by Hole Shift Process.

    Science.gov (United States)

    Kc, Chandra B; Lim, Gary N; D'Souza, Francis

    2016-04-20

    Sequential electron/hole transfer between energetically well-positioned entities of photosynthetic reaction center models is one of the commonly employed mechanisms to generate long-lived charge-separated states. A wealth of information, applicable towards light energy harvesting and building optoelectronic devices, has been acquired from such studies. In the present study, we report on the effect of spacer (direct or via phenoxy linkage) connecting the hole shifting agent, phenothiazine (PTZ), on photoinduced charge stabilization in subphthalocyanine-fullerene donor-acceptor conjugates. In these conjugates, the subphthalocyanine (SubPc) and fullerene (C60 ) served as primary electron donor and acceptor, respectively, while the phenothiazine entities act as hole shifting agents. The newly synthesized compounds were characterized by optical absorption and emission, computational, and electrochemical methods. The redox potentials measured using differential pulse voltammetry were used to estimate free-energy changes for charge separation, hole migration, and charge recombination processes. Using femto- and nanosecond transient absorption techniques, evidence for charge separation, and kinetics of charge separation and recombination were obtained in polar benzonitrile and nonpolar toluene solvents. In the conjugate where the phenothiazine entities are directly linked to SubPc, evidence for sequential electron transfer followed by hole shift leading to long-lived charge separated state was weak, primarily due to the delocalization of HOMO on both SubPc and PTZ entities. However, in case of the conjugate where the PTZ and SubPc are linked via phenoxy spacers, sequential electron transfer/hole shift was observed leading to the formation of long-lived charge-separated states. The present study brings out the importance of the spacer group connecting the hole shifting agent in model donor-acceptor conjugates to generate long-lived charge-separated states. PMID:27037628

  13. DFT methods for conjugated materials: From benchmarks to functionals

    Science.gov (United States)

    Sears, John; Bredas, Jean-Luc

    2012-02-01

    From a theoretical standpoint, many of the problems of interest in the study of pi-conjugated materials for organic electronics applications pose a particular challenge for many modern density functional theory methods. Systematic errors have been observed, for instance, in the description of charge-transfer excitations at donor/acceptor interfaces, in linear and non-linear polarizabilites, as well as in the geometric and electronic properties of conjugated polymers [1,2]. We will discuss recent results in our lab aimed at: (i) understanding the sources of error for some of these problems; (ii) addressing these errors using tuned long-range corrected functionals; and (iii) using these results to guide the development of state-of-the-art methodologies in a new open-source DFT code. [4pt] [1] J. S. Sears, T. Korzdorfer, C. R. Zhang, and J. L. Bredas, J. Chem. Phys. 135 151103 (2011)[0pt] [2] T. Korzdorfer, J. S. Sears, C. Sutton, and J. L. Bredas, J. Chem. Phys., accepted.

  14. Swift Electrofluorochromism of Donor-Acceptor Conjugated Polytriphenylamines.

    Science.gov (United States)

    Sun, Jingwei; Liang, Ziqi

    2016-07-20

    Electrofluorochromic (EFC) materials, which exhibit electrochemically controllable fluorescence, hold great promise in optoelectronic devices and biological analysis. Here we design such donor-acceptor (D-A) conjugated polymers-P(TPACO) and P(TCEC)-that contain the same electron-rich and oxidizable polytriphenylamine (PTPA) as π-backbone, yet with different electron-deficient ketone and cyano units as pendant groups, respectively. They both exhibit solvatochromic effects due to intrinsic characteristics of intramolecular charge transfer (ICT). Compared to P(TPACO), P(TCEC) shows stronger ICT, which leads to higher electrochemical oxidation potential and lower ion diffusion coefficient. Moreover, both polymers present simultaneous electrochromic (EC) and EFC behaviors with multistate display and remarkably rapid fluorescence response. The response time of P(TPACO) is as short as 0.19 s, nearly 4-fold faster than that of P(TCEC) (0.92 s). Such rapid response is found to be determined by the ion diffusion coefficient which is associated with the ICT nature. Finally, the EFC display device based on P(TPACO) is successfully demonstrated, which shows green fluorescence ON/OFF switching upon applied potentials. This work has successfully demonstrated that swift EFCs can be achieved by rational modulation of the ICT effect in such D-A conjugated polymers. PMID:27347724

  15. Design and Application of Antimicrobial Peptide Conjugates.

    Science.gov (United States)

    Reinhardt, Andre; Neundorf, Ines

    2016-01-01

    Antimicrobial peptides (AMPs) are an interesting class of antibiotics characterized by their unique antibiotic activity and lower propensity for developing resistance compared to common antibiotics. They belong to the class of membrane-active peptides and usually act selectively against bacteria, fungi and protozoans. AMPs, but also peptide conjugates containing AMPs, have come more and more into the focus of research during the last few years. Within this article, recent work on AMP conjugates is reviewed. Different aspects will be highlighted as a combination of AMPs with antibiotics or organometallic compounds aiming to increase antibacterial activity or target selectivity, conjugation with photosensitizers for improving photodynamic therapy (PDT) or the attachment to particles, to name only a few. Owing to the enormous resonance of antimicrobial conjugates in the literature so far, this research topic seems to be very attractive to different scientific fields, like medicine, biology, biochemistry or chemistry. PMID:27187357

  16. Design and Application of Antimicrobial Peptide Conjugates

    Directory of Open Access Journals (Sweden)

    Andre Reinhardt

    2016-05-01

    Full Text Available Antimicrobial peptides (AMPs are an interesting class of antibiotics characterized by their unique antibiotic activity and lower propensity for developing resistance compared to common antibiotics. They belong to the class of membrane-active peptides and usually act selectively against bacteria, fungi and protozoans. AMPs, but also peptide conjugates containing AMPs, have come more and more into the focus of research during the last few years. Within this article, recent work on AMP conjugates is reviewed. Different aspects will be highlighted as a combination of AMPs with antibiotics or organometallic compounds aiming to increase antibacterial activity or target selectivity, conjugation with photosensitizers for improving photodynamic therapy (PDT or the attachment to particles, to name only a few. Owing to the enormous resonance of antimicrobial conjugates in the literature so far, this research topic seems to be very attractive to different scientific fields, like medicine, biology, biochemistry or chemistry.

  17. A FIDAP and an empirical estimate of conjugate heat transfer of a graphite crucible

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, K.J.; Clarksean, R.L.

    1995-05-01

    A set of thermal analyses has been conducted to conservatively predict the heat transfer of a graphite crucible. The study used conjugate heat transfer to determine the cooling characteristics of a graphite crucible. Natural convection and conduction through the casting charge and the graphite crucible are examined. All of the analyses were conducted in non-dimensional form up to a Rayleigh number of 1 x 10{sup 8}. The parametric study examined the effect of increasing the internal heat generation of the casting charge. Data derived from an empirical estimate are compared to the FIDAP simulations. The two models are found to have good correlation.

  18. OFDM systems using passive phase conjugation

    OpenAIRE

    Fusco, V.; Xiao, P

    2012-01-01

    The present disclosure is related to a transmitter, a receiver, a method for transmitting information, and a method of receiving information in a system which simplifies receiver structure and improves the performance in an orthogonal frequency-division multiplexing (OFDM) system. The transmitter comprises a module for generating a passive phase conjugation probe signal for transmission. The receiver comprises a passive phase conjugation module. The method for transmitting information compris...

  19. Conjugation spaces and equivariant Chern classes

    OpenAIRE

    Pitsch, W.; Scherer, J

    2011-01-01

    Let $\\eta$ be a Real bundle, in the sense of Atiyah, over a space $X$. This is a complex vector bundle together with an involution which is compatible with complex conjugation. We use the fact that $BU$ has a canonical structure of a conjugation space, as defined by Hausmann, Holm, and Puppe, to construct equivariant Chern classes in certain equivariant cohomology groups of $X$ with twisted integer coefficients. We show that these classes determine the (non-equivariant) C...

  20. The Retentivity of Chaos under Topological Conjugation

    OpenAIRE

    Tianxiu Lu; Peiyong Zhu; Xinxing Wu

    2013-01-01

    The definitions of Devaney chaos (DevC), exact Devaney chaos (EDevC), mixing Devaney chaos (MDevC), and weak mixing Devaney chaos (WMDevC) are extended to topological spaces. This paper proves that these chaotic properties are all preserved under topological conjugation. Besides, an example is given to show that the Li-Yorke chaos is not preserved under topological conjugation if the domain is extended to a general metric space.

  1. Syntheses of conjugated polymers for photonics

    Czech Academy of Sciences Publication Activity Database

    Výprachtický, Drahomír; Cimrová, Věra; Kmínek, Ivan; Pavlačková, Petra

    2010-01-01

    Roč. 295, č. 1 (2010), s. 94-99. ISSN 1022-1360. [Prague Meetings on Macromolecules /73./ New Frontiers in Macromolecular Science: From Macromolecular Concepts of Living Matter to Polymers for Better Quality of Life. Prague, 05.07.2009-09.07.2009] R&D Projects: GA MŠk(CZ) 1M06031 Institutional research plan: CEZ:AV0Z40500505 Keywords : cis and trans isomers * conjugated polymer * conjugated polyelectrolyte Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Digital optical phase conjugation of fluorescence in turbid tissue

    OpenAIRE

    Vellekoop, I. M.; Cui, Meng; Yang, Changhuei

    2012-01-01

    We demonstrate a method for phase conjugating fluorescence. Our method, called reference free digital optical phase conjugation, can conjugate extremely weak, incoherent optical signals. It was used to phase conjugate fluorescent light originating from a bead covered with 0.5 mm of light-scattering tissue. The phase conjugated beam refocuses onto the bead and causes a local increase of over two orders of magnitude in the light intensity. Potential applications are in imaging, optical trapping...

  3. CHARGE Association

    Directory of Open Access Journals (Sweden)

    Semanti Chakraborty

    2012-01-01

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

  4. Disulfide-based multifunctional conjugates for targeted theranostic drug delivery.

    Science.gov (United States)

    Lee, Min Hee; Sessler, Jonathan L; Kim, Jong Seung

    2015-11-17

    Theranostics, chemical entities designed to combine therapeutic effects and imaging capability within one molecular system, have received considerable attention in recent years. Much of this interest reflects the promise inherent in personalized medicine, including disease-targeted treatments for cancer patients. One important approach to realizing this latter promise involves the development of so-called theranostic conjugates, multicomponent constructs that selectively target cancer cells and deliver cytotoxic agents while producing a readily detectable signal that can be monitored both in vitro and in vivo. This requires the synthesis of relatively complex systems comprising imaging reporters, masked chemotherapeutic drugs, cleavable linkers, and cancer targeting ligands. Ideally, the cleavage process should take place within or near cancer cells and be activated by cellular components that are associated with cancer states or specifically expressed at a higher level in cancer cells. Among the cleavable linkers currently being explored for the construction of such localizing conjugates, disulfide bonds are particularly attractive. This is because disulfide bonds are stable in most blood pools but are efficiently cleaved by cellular thiols, including glutathione (GSH) and thioredoxin (Trx), which are generally found at elevated levels in tumors. When disulfide bonds are linked to fluorophores, changes in emission intensity or shifts in the emission maxima are typically seen upon cleavage as the result of perturbations to internal charge transfer (ICT) processes. In well-designed systems, this allows for facile imaging. In this Account, we summarize our recent studies involving disulfide-based fluorescent drug delivery conjugates, including preliminary tests of their biological utility in vitro and in vivo. To date, a variety of chemotherapeutic agents, such as doxorubicin, gemcitabine, and camptothecin, have been used to create disulfide-based conjugates, as have

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

    Directory of Open Access Journals (Sweden)

    Tilley T.D.

    2013-03-01

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

  6. D-A conjugated polymers containing substituted thiophene, 1,3,4-oxadiazole and non-conjugation linkers: Synthesis and study of optical and electrochemical properties

    Indian Academy of Sciences (India)

    PRASHANTH KUMAR K R; UDAYAKUMAR D; SIJI NARENDRAN N K; CHANDRASEKHARAN K; RITU SRIVASTAVA

    2016-09-01

    In this communication, we report synthesis and characterization of new D-A conjugated polymers (P1-P3) consisting of electron-donating (D) 3,4-didodecyloxythiophene, electron-accepting (A) 1,3,4- oxadiazole unit and non-conjugation linkers. The conjugated segment in P1-P3 contains only five aromatic rings resulting in short conjugation length, but has an alternate D-A arrangement which significantly enhances the intramolecular charge transfer (ICT) interaction within the segment. As a result, these polymers exhibited lowoptical band gap in the range 2.51–2.76 eV. Fluorescence emission studies revealed that the polymer thin films emit intense blue light with emission maxima in the wavelength rage 430–480 nm. All three polymers undergo both oxidation and reduction processes under electrochemical conditions. Further, these polymers (P1–P3) exhibit low-lying HOMO and LUMO levels as a result of D-A structure of the conjugated segment. Polymer light-emitting devices were fabricated using these polymers as emissive layer with a device configuration of ITO/MoO₃/polymer/LiF/Al. The test device based on P2 emitted blue light with a low threshold voltage of 5 V. Z-scan studies reveal that the polymers exhibit a strong optical limiting behavior. The value of the nonlinear absorption coefficient (β) of polymers is of the order 10⁻¹¹m/W which indicates that these materials may be accomplished for fabricating optical limiters.

  7. Dye linked conjugated homopolymers: using conjugated polymer electroluminescence to optically pump porphyrin-dye emission

    DEFF Research Database (Denmark)

    Nielsen, K.T.; Spanggaard, H.; Krebs, Frederik C

    2004-01-01

    Zinc-porphyrin dye molecules were incorporated into the backbone of a conjugated polymer material by a method, which allowed for the incorporation of only one zinc-porphyrin dye molecule into the backbone of each conjugated polymer molecule. The electronic properties of the homopolymer were...

  8. Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer – a promising material for high-performance solar cells

    International Nuclear Information System (INIS)

    Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDTTHD − DTBTff) was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT). We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV) measurements and diffusion length determinaton using surface photovoltage measurements

  9. Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer – a promising material for high-performance solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Toušek, J., E-mail: jiri.tousek@mff.cuni.cz; Toušková, J.; Chomutová, R. [Charles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, 182 00 Prague 8 (Czech Republic); Remeš, Z.; Čermák, J. [Institute of Physics of the Academy of Sciences, Cukrovarnická 10, 162 53 Prague 6 (Czech Republic); Helgesen, M.; Carlé, J. E.; Krebs, F. C. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark)

    2015-12-15

    Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDT{sub THD} − DTBTff) was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT). We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV) measurements and diffusion length determinaton using surface photovoltage measurements.

  10. Electrical characterization of fluorinated benzothiadiazole based conjugated copolymer – a promising material for high-performance solar cells

    Directory of Open Access Journals (Sweden)

    J. Toušek

    2015-12-01

    Full Text Available Measurements of electrical conductivity, electron work function, carrier mobility of holes and the diffusion length of excitons were performed on samples of conjugated polymers relevant to polymer solar cells. A state of the art fluorinated benzothiadiazole based conjugated copolymer (PBDTTHD − DTBTff was studied and benchmarked against the reference polymer poly-3-hexylthiophene (P3HT. We employed, respectively, four electrode conductivity measurements, Kelvin probe work function measurements, carrier mobility using charge extraction by linearly increasing voltage (CELIV measurements and diffusion length determinaton using surface photovoltage measurements.

  11. Workplace Charging. Charging Up University Campuses

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-01

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

  12. Conjugate gradient algorithms using multiple recursions

    Energy Technology Data Exchange (ETDEWEB)

    Barth, T.; Manteuffel, T.

    1996-12-31

    Much is already known about when a conjugate gradient method can be implemented with short recursions for the direction vectors. The work done in 1984 by Faber and Manteuffel gave necessary and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented with a single recursion of a certain form. However, this form does not take into account all possible recursions. This became evident when Jagels and Reichel used an algorithm of Gragg for unitary matrices to demonstrate that the class of matrices for which a practical conjugate gradient algorithm exists can be extended to include unitary and shifted unitary matrices. The implementation uses short double recursions for the direction vectors. This motivates the study of multiple recursion algorithms.

  13. Complex conjugate pairs in stationary Sturmians

    International Nuclear Information System (INIS)

    Sturmian expansions enable a simply accurate separable specification of two nucleon t matrices based upon realistic two nucleon interactions. Sturmian eigenstates specified by stationary scattering boundary conditions are particularly useful in that context, and they can be calculated by solving a generalised eigenvalue equation using real and symmetric matrices. In general, the spectrum of such an equation may contain complex eigenvalues. But to each complex eigenvalues there is a corresponding conjugate partner. In studies using realistic two nucleon potentials, and in certain positive energy intervals, these complex conjugated pairs indeed appear in the Sturmian spectrum. However, it is demonstrated that it is possible to recombine the complex conjugate pairs and corresponding states into a new, (and useful) pair of real eigenvalues and eigenstates with which of effect separable expansions of the (real) two nucleon reactance matrices. 8 refs

  14. Complex conjugate pairs in stationary Sturmian eigenstates

    International Nuclear Information System (INIS)

    Sturmian eigenstates specified by stationary scattering boundary conditions are particularly useful in contexts such as forming simple separable two nucleon t matrices, and are determined via solution of generalized eigenvalue equation using real and symmetric matrices. In general, the spectrum of such an equation may contain complex eigenvalues. But to each complex eigenvalue there is a corresponding conjugate partner. In studies using realistic nucleon-nucleon potentials, and in certain positive energy intervals, these complex conjugated pairs indeed appear in the Sturmian spectrum. However, as we demonstrate herein, it is possible to recombine the complex conjugate pairs and corresponding states into a new, sign-definite pair of real quantities with which to effect separable expansions of the (real) nucleon-nucleon reactance matrices

  15. Conjugate Meningococcal Vaccines Development: GSK Biologicals Experience

    Directory of Open Access Journals (Sweden)

    Jacqueline M. Miller

    2011-01-01

    Full Text Available Meningococcal diseases are serious threats to global health, and new vaccines specifically tailored to meet the age-related needs of various geographical areas are required. This paper focuses on the meningococcal conjugate vaccines developed by GSK Biologicals. Two combined conjugate vaccines were developed to help protect infants and young children in countries where the incidence of meningococcal serogroup C or serogroup C and Y disease is important: Hib-MenC-TT vaccine, which offers protection against Haemophilus influenzae type b and Neisseria meningitidis serogroup C diseases, is approved in several countries; and Hib-MenCY-TT vaccine, which adds N. meningitidis serogroup Y antigen, is currently in the final stages of development. Additionally, a tetravalent conjugate vaccine (MenACWY-TT designed to help protect against four meningococcal serogroups is presently being evaluated for global use in all age groups. All of these vaccines were shown to be highly immunogenic and to have clinically acceptable safety profiles.

  16. Complex Conjugate Pairs in Stationary Sturmians

    CERN Document Server

    Dortmans, P J; Pisent, G; Amos, K A

    1993-01-01

    Sturmian eigenstates specified by stationary scattering boundary conditions are particularly useful in contexts such as forming simple separable two nucleon t matrices, and are determined via solution of generalised eigenvalue equation using real and symmetric matrices. In general, the spectrum of such an equation may contain complex eigenvalues. But to each complex eigenvalue there is a corresponding conjugate partner. In studies using realistic nucleon--nucleon potentials, and in certain positive energy intervals, these complex conjugated pairs indeed appear in the Sturmian spectrum. However, as we demonstrate herein, it is possible to recombine the complex conjugate pairs and corresponding states into a new, sign--definite pair of real quantities with which to effect separable expansions of the (real) nucleon--nucleon reactance matrices.

  17. Triplex glue by synthesizing conjugated flexible intercalators.

    Science.gov (United States)

    Pedersen, Erik B; Osman, Amany M A; Globisch, Daniel; Paramasivam, Manikandan; Cogoi, Susanna; Bomholt, Niels; Jørgensen, Per T; Xodo, Luigi E; Filichev, Vyacheslav V

    2008-01-01

    Bulge insertions of conjugated intercalators into the DNA triplex structure are found to give a dramatic contribution to the triplex stability. On the other hand insertions of conjugated intercalators are found to diminish quadruplex structures and in this way breaking down the self association of G-rich oligonucleotides under physiologically potassium ion conditions. A large number of intercalators are described here and they all result in dramatic increases of thermal stability of the corresponding triplexes. Another interesting aspect of conjugated intercalators is their use for assembling alternate strand triplexes. Targeting of neighbouring purine sequences on each their strand in the duplex DNA is a challenge for the 5'- 5' connectivity of the TFOs because of a large distance between the 5'-ends. The intercalator approach offers a linkage with the proper combination of flexibility and rigidity to produce alternate strand triplexes with higher stability than a similar wild type triplex of the same total length. PMID:18776241

  18. Tight-binding treatment of conjugated polymers

    DEFF Research Database (Denmark)

    Lynge, Thomas Bastholm

    This PhD thesis concerns conjugated polymers which constitute a constantly growing research area. Today, among other things, conjugated polymers play a role in plastic based solar cells, photodetectors and light emitting diodes, and even today such plastic-based components constitute an alternative...... of tomorrow. This thesis specifically treats the three conjugated polymers trans-polyacetylene (tPA), poly(para-phenylene) (PPP) and poly(para-phe\\-nylene vinylene) (PPV). The present results, which are derived within the tight-binding model, are divided into two parts. In one part, analytic results...... are derived for the optical properties of the polymers expressed in terms of the optical susceptibility both in the presence and in the absence of a static electric field. In the other part, the cumputationally efficient Density Functional-based Tight-Binding (DFTB) model is applied to the description...

  19. Conjugation in hydrogen-bonded systems

    CERN Document Server

    Novakovskaya, Yulia V

    2012-01-01

    Analysis of the electron density distribution in clusters composed of hydrogen fluoride, water, and ammonia molecules, especially within the hydrogen-bond domains, reveals the existence of both \\sigma- and \\pi-binding between molecules. The \\sigma-kind density distribution determines the mutual orientation of molecules. A \\pi-system may be delocalized conjugated, which provides additional stabilization of molecular clusters. In those clusters where the sequence of hydrogen bonds is not planar, a peculiar kind of \\pi-conjugation exists. HF anion and H5O2 cation are characterized by quasi-triple bonds between the electronegative atoms. The most long-lived species stabilized by delocalized \\pi-binding are rings and open or closed hoops composed of fused rings. It is conjugated \\pi-system that determines cooperativity phenomenon.

  20. Phase conjugation of high energy lasers.

    Energy Technology Data Exchange (ETDEWEB)

    Bliss, David Emery; Valley, Michael T.; Atherton, Briggs W.; Bigman, Verle; Boye, Lydia Ann; Broyles, Robin Scott; Kimmel, Mark W.; Law, Ryan J.; Yoder, James R.

    2013-01-01

    In this report we explore claims that phase conjugation of high energy lasers by stimulated Brillouin scattering (SBS) can compensate optical aberrations associated with severely distorted laser amplifier media and aberrations induced by the atmosphere. The SBS media tested was a gas cell pressurized up to 300 psi with SF6 or Xe or both. The laser was a 10 Hz, 3J, Q-switched Nd:YAG with 25 ns wide pulses. Atmospheric aberrations were created with space heaters, helium jets and phase plates designed with a Kolmogorov turbulence spectrum characterized by a Fried parameter, ro , ranging from 0.6 - 6.0 mm. Phase conjugate tests in the laboratory were conducted without amplification. For the strongest aberrations, D/ro ~ 20, created by combining the space heaters with the phase plate, the Strehl ratio was degraded by a factor of ~50. Phase conjugation in SF6 restored the peak focusable intensity to about 30% of the original laser. Phase conjugate tests at the outdoor laser range were conducted with laser amplifiers providing gain in combination with the SBS cell. A large 600,000 BTU kerosene space heater was used to create turbulence along the beam path. An atmospheric structure factor of Cn2 = 5x10-13 m2/3 caused the illumination beam to expand to a diameter 250mm and overfill the receiver. The phase conjugate amplified return could successfully be targeted back onto glints 5mm in diameter. Use of a lenslet arrays to lower the peak focusable intensity in the SBS cell failed to produce a useful phase conjugate beam; The Strehl ratio was degraded with multiple random lobes instead of a single focus. I will review literature results which show how multiple beams can be coherently combined by SBS when a confocal reflecting geometry is used to focus the laser in the SBS cell.

  1. Effects of solution conditions on characteristics and size exclusion chromatography of pneumococcal polysaccharides and conjugate vaccines.

    Science.gov (United States)

    Hadidi, Mahsa; Buckley, John J; Zydney, Andrew L

    2016-11-01

    Molecular properties of bacterial polysaccharides and protein-polysaccharide conjugates play an important role in the efficiency and immunogenicity of the final vaccine product. Size exclusion chromatography (SEC) is commonly used to analyze and characterize biopolymers, including capsular polysaccharides. The objective of this work was to determine the effects of solution ionic strength and pH on the SEC retention of several capsular polysaccharides from S. pneumoniae bacteria in their native and conjugated forms. The retention time of the charged polysaccharides increased with increasing ionic strength and decreasing pH due to compaction of the polysaccharides associated with a reduction in the intramolecular electrostatic interactions. The calculated radius of gyration was in good agreement with model calculations based on the worm-like chain model accounting for the increase in chain stiffness and excluded volume of the charged polysaccharide at low ionic strength. These results provide important insights into the effects of solution ionic strength on physical properties and SEC behavior of capsular polysaccharides and their corresponding conjugates. PMID:27516244

  2. Conjugate metamaterials and the perfect lens

    CERN Document Server

    Xu, Yadong; Xu, Lin; Chen, Huanyang

    2015-01-01

    In this letter, we show how transformation optics makes it possible to design what we call conjugate metamaterials. We show that these materials can also serve as substrates for making a subwavelength-resolution lens. The so-called "perfect lens", which is a lens that could focus all components of light (including propagating and evanescent waves), can be regarded as a limiting case, in which the respective conjugate metamaterials approach the characteristics of left-handed metamaterials, which have a negative refractive index.

  3. Theoretical study of conjugated porphyrin polymers

    DEFF Research Database (Denmark)

    Pedersen, T.G.; Lynge, T.B.; Kristensen, P.K.; Johansen, P.M.

    The optical gap of conjugated triply linked porphyrin chains is exceptionally low (similar to 0.5 eV). Hence, such chains are candidates for organic infrared detectors and solar cells harvesting the infrared part of the solar spectrum. However, a low exciton binding energy is required for these...... applications. From a theoretical analysis of excitons in long metalloporphyrin chains, we demonstrate that the binding energy is much lower than in usual conjugated polymers. Our calculated absorption spectra are in good agreement with measurements. (c) 2004 Elsevier B.V. All rights reserved....

  4. Conjugated polymers as actuators: modes of actuation

    DEFF Research Database (Denmark)

    Skaarup, Steen

    The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

  5. Conjugated Polymers as Actuators: Modes of Actuation

    DEFF Research Database (Denmark)

    Skaarup, Steen

    The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

  6. A DNA-Fullerene Conjugate as a Template for Supramolecular Chromophore Assemblies: Towards DNA-Based Solar Cells.

    Science.gov (United States)

    Ensslen, Philipp; Gärtner, Stefan; Glaser, Konstantin; Colsmann, Alexander; Wagenknecht, Hans-Achim

    2016-01-01

    A fullerene was covalently attached to a (dA)20 template that serves as structural scaffold to self-assemble an ordered and mixed array of ethynyl-pyrene- and ethynyl-Nile-red-nucleoside conjugates. Fluorescence spectroscopy revealed evidence for energy transfer between the two different chromophores. Moreover, fluorescence quenching is significantly enhanced by the attached fullerene in mixed assemblies of different chromophore ratios. This indicates exciton dissociation by electron transfer from the photo-generated exciton on the chromophore stack to the fullerene. The fullerene-DNA-conjugate was integrated as a photo-active layer in solar cells that showed charge-carrier generation in the spectral regime of all three components of the conjugate. This work clearly demonstrates that DNA is suitable as structural element for chromophore assemblies in future organic optoelectronic devices, such as solar cells. PMID:26689149

  7. Conjugate Gradient Methods with Armijo-type Line Searches

    Institute of Scientific and Technical Information of China (English)

    Yu-Hong DAI

    2002-01-01

    Two Armijo-type line searches are proposed in this paper for nonlinear conjugate gradient methods.Under these line searches, global convergence results are established for several famous conjugate gradient method.

  8. An efficient conjugate directions method without linear minimization

    International Nuclear Information System (INIS)

    An algorithm of conjugate directions for unconstrained minimization is presented, called Single-Step Conjugate Directions Method (SSCDM) that differs from the known algorithms in the following points: (1) only one step is made on each iteration, without the linear searches of a minimum; (2) each step includes simultaneous displacements along all conjugate directions found on previous steps (instead of consequent steps along each conjugate vector); (3) each new conjugate direction is determined by the general procedure of construction of conjugate vectors, without assumption that minima along the conjugate directions were reached on previous steps. These features of the algorithm eliminate high sensitivity to computation errors pertinent to usual methods of conjugate directions and simultaneously significantly reduce the running time. Performance of the algorithm is demonstrated by applying it to a set of standard test-functions and solving a problem of high-energy physics with a Monte-Carlo-type objective function

  9. Two Means of Compensating Fiber Nonlinearity Using Optical Phase Conjugation

    OpenAIRE

    Wei, Haiqing; Plant, David V.

    2003-01-01

    Two fiber lines may compensate each other for nonlinearity with the help of optical phase conjugation. The pair of fiber lines and the optical signals in them may be either mirror-symmetric or translationally symmetric about the conjugator.

  10. Reversible CO2 Capture by Conjugated Ionic Liquids through Dynamic Covalent Carbon-Oxygen Bonds.

    Science.gov (United States)

    Pan, Mingguang; Cao, Ningning; Lin, Wenjun; Luo, Xiaoyan; Chen, Kaihong; Che, Siying; Li, Haoran; Wang, Congmin

    2016-09-01

    The strong chemisorption of CO2 is always accompanied by a high absorption enthalpy, and traditional methods to reduce the absorption enthalpy lead to decreased CO2 capacities. Through the introduction of a large π-conjugated structure into the anion, a dual-tuning approach for the improvement of CO2 capture by anion-functionalized ionic liquids (ILs) resulted in a high capacity of up to 0.96 molCO2  mol-1IL and excellent reversibility. The increased capacity and improved desorption were supported by quantum chemical calculations, spectroscopic investigations, and thermogravimetric analysis. The increased capacity may be a result of the strengthened dynamic covalent bonds in these π-electron-conjugated structures through anion aggregation upon the uptake of CO2 , and the improved desorption originates from the charge dispersion of interaction sites through the large π-electron delocalization. These results provide important insights into effective strategies for CO2 capture. PMID:27458723

  11. Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

    Directory of Open Access Journals (Sweden)

    Ioan Botiz

    2014-03-01

    Full Text Available It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties.

  12. Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

    KAUST Repository

    Botiz, Ioan

    2014-03-19

    It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. © 2014 by the authors.

  13. Constructive Conjugate Codes for Quantum Error Correction and Cryptography

    OpenAIRE

    Hamada, Mitsuru

    2007-01-01

    A conjugate code pair is defined as a pair of linear codes either of which contains the dual of the other. A conjugate code pair represents the essential structure of the corresponding Calderbank-Shor-Steane (CSS) quantum error-correcting code. It is known that conjugate code pairs are applicable to quantum cryptography. In this work, a polynomial construction of conjugate code pairs is presented. The constructed pairs achieve the highest known achievable rate on additive channels, and are de...

  14. Unsaturated fatty acids are inhibitors of bacterial conjugation

    OpenAIRE

    Fernandez-Lopez, R.; Machón, C.; Longshaw, C.; Martin, S.; Molin, S; E. Zechner; Espinosa, M; Lanka, E; de la Cruz, F

    2005-01-01

    This report describes a high-throughput assay to identify substances that reduce the frequency of conjugation in Gram-negative bacteria. Bacterial conjugation is largely responsible for the spread of multiple antibiotic resistances in human pathogens. Conjugation inhibitors may provide a means to control the spread of antibiotic resistance. An automated conjugation assay was developed that used plasmid R388 and a laboratory strain of Escherichia coli as a model system, and bioluminescence as ...

  15. Interaction of antithrombin III with preadsorbed albumin-heparin conjugates

    OpenAIRE

    Hennink, W.E.; Ebert, C.D.; Kim, S. W.; Breemhaar, W.; Bantjes, A.; Feijen, J.

    1984-01-01

    The adsorption of antithrombin III (AT III) onto polystyrene surfaces preadsorbed with albumin or albuminheparin conjugates was studied using a two step enzyme immuno assay. When AT III-buffer solutions were used, the highest adsorption values were measured on high affinity albumin-heparin conjugate pretreated surfaces. Less AT III adsorption was found on nonfractionated albumin-heparin conjugate preadsorbed surfaces. AT III adsorption could also be detected on low affinity conjugate and albu...

  16. Tumor Selective Silencing Using an RNAi-Conjugated Polymeric Nanopharmaceutical.

    Science.gov (United States)

    Svenson, Sonke; Case, Roy I; Cole, Roderick O; Hwang, Jungyeon; Kabir, Sujan R; Lazarus, Douglas; Lim Soo, Patrick; Ng, Pei-Sze; Peters, Christian; Shum, Pochi; Sweryda-Krawiec, Beata; Tripathi, Snehlata; van der Poll, Derek; Eliasof, Scott

    2016-03-01

    Small interfering RNA (siRNA) therapeutics have potential advantages over traditional small molecule drugs such as high specificity and the ability to inhibit otherwise "undruggable" targets. However, siRNAs have short plasma half-lives in vivo, can induce a cytokine response, and show poor cellular uptake. Formulating siRNA into nanoparticles offers two advantages: enhanced siRNA stability against nuclease degradation beyond what chemical modification alone can provide; and improved site-specific delivery that takes advantage of the enhanced permeability and retention (EPR) effect. Existing delivery systems generally suffer from poor delivery to tumors. Here we describe the formation and biological activity of polymeric nanopharmaceuticals (PNPs) based on biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) conjugated to siRNA via an intracellular cleavable disulfide linker (PLGA-siRNA). Additionally, these PNPs contain (1) PLGA conjugated to polyethylene glycol (PEG) for enhanced pharmacokinetics of the nanocarrier; (2) a cation for complexation of siRNA and charge compensation to avoid high negative zeta potential; and (3) neutral poly(vinyl alcohol) (PVA) to stabilize the PNPs and support the PEG shell to prevent particle aggregation and protein adsorption. The biological data demonstrate that these PNPs achieve prolonged circulation, tumor accumulation that is uniform throughout the tumor, and prolonged tumor-specific knockdown. PNPs employed in this study had no effect on body weight, blood cell count, serum chemistry, or cytokine response at doses >10 times the effective dose. PNPs, therefore, constitute a promising solution for achieving durable siRNA delivery and gene silencing in tumors. PMID:26835715

  17. Tuning The Optical, Charge Injection, and Charge Transport Properties of Organic Electronic Devices

    Science.gov (United States)

    Zalar, Peter

    Since the early 1900's, synthetic insulating polymers (plastics) have slowly taken over the role that traditional materials like wood or metal have had as basic components for construction, manufactured goods, and parts. Plastics allow for high throughput, low temperature processing, and control of bulk properties through molecular modifications. In the same way, pi-conjugated organic molecules are emerging as a possible substitute for inorganic materials due to their electronic properties. The semiconductive nature of pi-conjugated materials make them an attractive candidate to replace inorganic materials, primarily due to their promise for low cost and large-scale production of basic semiconducting devices such as light-emitting diodes, solar cells, and field-effect transistors. Before organic semiconductors can be realized as a commercial product, several hurdles must be cleared. The purpose of this dissertation is to address three distinct properties that dominate the functionality of devices harnessing these materials: (1) optical properties, (2) charge injection, and (3) charge transport. First, it is shown that the electron injection barrier in the emissive layer of polymer light-emitting diodes can be significantly reduced by processing of novel conjugated oligoelectrolytes or deoxyribonucleic acid atop the emissive layer. Next, the charge transport properties of several polymers could be modified by processing them from solvents containing small amounts of additives or by using regioregular and enantiopure chemical structures. It is then demonstrated that the optical and electronic properties of Lewis basic polymer structures can be readily modified by interactions with strongly electron-withdrawing Lewis acids. Through red-shifted absorption, photoluminescence, and electroluminescence, a single pi-conjugated backbone can be polychromatic. In addition, interaction with Lewis acids can remarkably p-dope the hole transport of the parent polymer, leading to a

  18. Conjugate problems in convective heat transfer

    CERN Document Server

    Dorfman, Abram S

    2009-01-01

    The conjugate heat transfer (CHT) problem takes into account the thermal interaction between a body and fluid flowing over or through it, a key consideration in both mechanical and aerospace engineering. Presenting more than 100 solutions of non-isothermal and CHT problems, this title considers the approximate solutions of CHT problems.

  19. Conjugate Addition-Initiated Nazarov Cyclization

    OpenAIRE

    Brooks, Joshua L.; Caruana, Patrick A.; Frontier, Alison J.

    2011-01-01

    A reaction sequence involving the 1,6-conjugate addition of a nucleophile to a dienyl diketone followed by Nazarov cyclization is described. Several nucleophiles are identified as competent initiators for the sequence. A different reaction outcome is is observed when catalytic amounts of nucleophile are employed, involving elimination of the nucleophile after the electrocyclization.

  20. Conjugate Function Method for Numerical Conformal Mappings

    CERN Document Server

    Hakula, Harri; Rasila, Antti

    2011-01-01

    We present a method for numerical computation of conformal mappings from simply or doubly connected domains onto so-called canonical domains, which in our case are rectangles or annuli. The method is based on conjugate harmonic functions and properties of quadrilaterals. Several numerical examples are given.

  1. The conjugation method in symplectic dynamics

    OpenAIRE

    Hernández-Corbato, Luis; Presas, Francisco

    2016-01-01

    We prove the existence of minimal symplectomorphisms and strictly ergodic contactomorphisms on manifolds which admit a locally free $\\mathbb{S}^1$--action by symplectomorphisms and contactomorphisms, respectively. The proof adapts the conjugation method, introduced by Anosov and Katok, to the contact and symplectic setting.

  2. Stress on Second Conjugation Infinitives in Italian.

    Science.gov (United States)

    Davis, Stuart; And Others

    1987-01-01

    Reviews the limited amount of research regarding ways in which primary stress is assigned to second conjugation infinitives in Italian and then proposes a new perspective taking into consideration root vowels, root-final consonants, syllable onset, monosyllabic vs. polysyllabic roots, and canonical form. (CB)

  3. Conjugated Polymer Actuators: Prospects and Limitations

    DEFF Research Database (Denmark)

    Skaarup, Steen

    Actuators constructed with a conjugated polymer as the active part have been predicted to have a number of highly desirable properties: Large mechanical strength, high power density, i.e. high actuation speeds possible, sufficient maximum strain values, high reversibility and safe, low voltages (1...

  4. Stochastic differential equations used to model conjugation

    DEFF Research Database (Denmark)

    Philipsen, Kirsten Riber; Christiansen, Lasse Engbo

    Stochastic differential equations (SDEs) are used to model horizontal transfer of antibiotic resis- tance by conjugation. The model describes the concentration of donor, recipient, transconjugants and substrate. The strength of the SDE model over the traditional ODE models is that the noise can be...

  5. Women experiencing the intergenerationality of conjugal violence

    Directory of Open Access Journals (Sweden)

    Gilvânia Patrícia do Nascimento Paixão

    2015-10-01

    Full Text Available Objective: to analyze the family relationship, in childhood and adolescence, of women who experience conjugal violence.Method: qualitative study. Interviews were held with 19 women, who were experiencing conjugal violence, and who were resident in a community in Salvador, Bahia, Brazil. The project was approved by the Research Ethics Committee (N. 42/2011.Results: the data was organized using the Discourse of the Collective Subject, identifying the summary central ideas: they witnessed violence between their parents; they suffered repercussions from the violence between their parents: they were angry about the mother's submission to her partner; and they reproduced the conjugal violence. The discourse showed that the women witnessed, in childhood and adolescence, violence between their parents, and were injured both physically and psychologically. As a result of the mother's submission, feelings of anger arose in the children. However, in the adult phase of their own lives, they noticed that their conjugal life resembled that of their parents, reproducing the violence.Conclusion: investment is necessary in strategies designed to break inter-generational violence, and the health professionals are important in this process, as it is a phenomenon with repercussions in health. Because they work in the Family Health Strategy, which focuses on the prevention of harm and illness, health promotion and interdepartmentality, the nurses are essential in the process of preventing and confronting this phenomenon.

  6. Bacillus thuringiensis Conjugation in Simulated Microgravity

    Science.gov (United States)

    Beuls, Elise; van Houdt, Rob; Leys, Natalie; Dijkstra, Camelia; Larkin, Oliver; Mahillon, Jacques

    2009-10-01

    Spaceflight experiments have suggested a possible effect of microgravity on the plasmid transfer among strains of the Gram-positive Bacillus thuringiensis, as opposed to no effect recorded for Gram-negative conjugation. To investigate these potential effects in a more affordable experimental setup, three ground-based microgravity simulators were tested: the Rotating Wall Vessel (RWV), the Random Positioning Machine (RPM), and a superconducting magnet. The bacterial conjugative system consisted in biparental matings between two B. thuringiensis strains, where the transfer frequencies of the conjugative plasmid pAW63 and its ability to mobilize the nonconjugative plasmid pUB110 were assessed. Specifically, potential plasmid transfers in a 0-g position (simulated microgravity) were compared to those obtained under 1-g (normal gravity) condition in each device. Statistical analyses revealed no significant difference in the conjugative and mobilizable transfer frequencies between the three different simulated microgravitational conditions and our standard laboratory condition. These important ground-based observations emphasize the fact that, though no stimulation of plasmid transfer was observed, no inhibition was observed either. In the case of Gram-positive bacteria, this ability to exchange plasmids in weightlessness, as occurs under Earth's conditions, should be seen as particularly relevant in the scope of spread of antibiotic resistances and bacterial virulence.

  7. Compositions for directed alignment of conjugated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

    2016-04-19

    Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

  8. New Antibody Conjugates in Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Serengulam V. Govindan

    2010-01-01

    Full Text Available Targeting of radiation, drugs, and protein toxins to cancers selectively with monoclonal antibodies (MAbs has been a topic of considerable interest and an area of continued development. Radioimmunotherapy (RAIT of lymphoma using directly labeled MAbs is of current interest after approval of two radiolabeled anti-CD20 MAbs, as illustrated with the near 100% overall response rate obtained in a recent clinical trial using an investigational radiolabeled anti-CD22 MAb, 90Y-epratuzumab. The advantage of pretargeted RAIT over directly labeled MAbs is continuing to be validated in preclinical models of lymphoma and solid tumors. Importantly, the advantages of combining RAIT with radiation sensitizers, with immunotherapy, or a drug conjugate targeting a different antigen are being studied clinically and preclinically. The area of drug-conjugated antibodies is progressing with encouraging data published for the trastuzumab-DM1 conjugate in a phase I clinical trial in HER2-positive breast cancer. The Dock-and-Lock platform technology has contributed to the design and the evaluation of complex antibody-cytokine and antibody-toxin conjugates. This review describes the advances made in these areas, with illustrations taken from advances made in the authors' institutions.

  9. Conjugated Educational System: Notion, Structure, Educational Potential 

    OpenAIRE

    Andrei A. Ostapenko; Dar'ya S. Tkach

    2012-01-01

    The article indicates the ways to decrease risk from teenagers and youth’s growing-up in today’s Russia by development of fundamental models of conjugated educational systems and their mass implementation in educational practice, introduces the notion of “conjugated educational system” for scientific use, describes types of conjugation and educational results of submitted models use.

  10. Synthesis of Indomethacin Conjugates with D-Glucosamine

    Institute of Scientific and Technical Information of China (English)

    Yi Chun ZHANG; Ying Xia LI; Hua Shi GUAN

    2005-01-01

    Two series of indomethacin conjugates with D-glucosamine were prepared with the objectives of reducing ulcerogenic potency, increasing the bioavailability of indomethacin and exerting the coordinative effects on osteoarthritis. The structures of the conjugates were identified by 1H NMR and 13C NMR. The ester conjugates inhibited edema as potent as indomethacin.

  11. JIMWLK evolution: From color charges to rapidity correlations

    International Nuclear Information System (INIS)

    We study multi-particle production with rapidity correlations in high-energy p+A collisions. In the context of the Color Glass Condensate, the evolution for such correlations is governed by a generalization of the JIMWLK equation which evolves the strong nuclear fields both in the amplitude and in the complex conjugate one. We give the equivalent Langevin formulation, whose main ingredient is the color charge density linked to a projectile parton (a Wilson line)

  12. Design, syntheses, and studies of supramolecular porphyrin-fullerene conjugates, using bis-18-crown-6 appended porphyrins and pyridine or alkyl ammonium functionalized fullerenes.

    Science.gov (United States)

    D'Souza, Francis; Chitta, Raghu; Gadde, Suresh; McCarty, Amy L; Karr, Paul A; Zandler, Melvin E; Sandanayaka, Atula S D; Araki, Yasuyaki; Ito, Osamu

    2006-03-30

    Photoinduced electron-transfer processes in cis and trans functionalized bis-18-crown-6 porphyrin self-assembled with fullerene functionalized with pyridine or alkylammonium cation entities are reported. The structural integrity of the newly formed supramolecular conjugates was accomplished by optical absorption and emission, electron spray ionization mass, electrochemistry, and semiempirical PM3 calculations. A 1:2 stoichiometry of the supramolecular porphyrin:fullerene conjugates was deduced from these studies. The conjugates revealed stable "two-point"' binding involving metal-ligand coordination and alkylammonium cation-crown ether binding or only the latter type of binding depending upon the functionality of the fullerene and metal ion in the porphyrin cavity. The effect of the variation on free energy changes of charge separation and the charge recombination was achieved by varying the metal ion in the porphyrin cavity. The charge-separation rates (k(CS)) determined from the picosecond time-resolved emission studies were generally higher for the cis bis-crown functionalized porphyrins than those of the corresponding trans ones. A comparison of the k(CS) values reported earlier for 1:1 porphyrin-fullerene conjugates with a similar self-assembly mechanism suggested that employing a higher number of acceptor entities improves the electron-transfer rates. The calculated charge-recombination rates (k(CR)) were 2-3 orders of magnitude smaller than the k(CS) values, suggesting the occurrence of the charge recombination process in the Marcus inverted region. The lifetimes of the radical ion pair (tau(RIP)) ranged between 46 and 233 ns indicating charge stabilization in the studied conjugates. PMID:16553397

  13. Through-bond photoinduced electron transfer in a porphyrin-fullerene conjugate held by a Hamilton type hydrogen bonding motif.

    Science.gov (United States)

    D'Souza, Francis; Venukadasula, Ganesh M; Yamanaka, Ken-ichi; Subbaiyan, Navaneetha K; Zandler, Melvin E; Ito, Osamu

    2009-03-21

    Control over the occurrence of through-bond electron transfer in self-assembled donor-acceptor conjugates is often difficult, since through-space electron transfer also competes due to the flexible nature of the spacer used to link the entities. In the present study, we have constructed a self-assembled donor-acceptor conjugate held solely by complementary hydrogen bonding and established through-bond electron transfer. The protocol used here is a Hamilton type hydrogen bonding motif involving self-assembly of a carboxylic acid functionalized porphyrin and 2-aminopyridine functionalized fullerene. Owing to the presence of two-point hydrogen bonds, the structure of the dyad is free from rotation with a donor-acceptor distance positioned appropriately to justify the through-bond electron transfer. Detailed spectral, computational and photochemical studies reveal efficient photoinduced charge separation and slow charge recombination in the studied conjugate, thus, bringing out the fundamental advantages of the directional hydrogen-bonding in the construction of donor-acceptor conjugates based on biomimetic principles and their functional role in governing electron transfer events. PMID:19262925

  14. Pulmonary toxicity and kinetic study of Cy5.5-conjugated superparamagnetic iron oxide nanoparticles by optical imaging

    International Nuclear Information System (INIS)

    Recent advances in the development of nanotechnology and devices now make it possible to accurately deliver drugs or genes to the lung. Magnetic nanoparticles can be used as contrast agents, thermal therapy for cancer, and be made to concentrate to target sites through an external magnetic field. However, these advantages may also become problematic when taking into account safety and toxicological factors. This study demonstrated the pulmonary toxicity and kinetic profile of anti-biofouling polymer coated, Cy5.5-conjugated thermally cross-linked superparamagnetic iron oxide nanoparticles (TCL-SPION) by optical imaging. Negatively charged, 36 nm-sized, Cy5.5-conjugated TCL-SPION was prepared for optical imaging probe. Cy5.5-conjugated TCL-SPION was intratracheally instilled into the lung by a non-surgical method. Cy5.5-conjugated TCL-SPION slightly induced pulmonary inflammation. The instilled nanoparticles were distributed mainly in the lung and excreted in the urine via glomerular filtration. Urinary excretion was peaked at 3 h after instillation. No toxicity was found under the concentration of 1.8 mg/kg and the half-lives of nanoparticles in the lung and urine were estimated to be about 14.4 ± 0.54 h and 24.7 ± 1.02 h, respectively. Although further studies are required, our results showed that Cy5.5-conjugated TCL-SPION can be a good candidate for use in pulmonary delivery vehicles and diagnostic probes.

  15. Controlled release of B-carotene in B-lactoglobulin-dextran conjugates nanoparticles in vitro digestion and the transport with Caco-2 monolayers

    Science.gov (United States)

    Undesirable aggregation of nanoparticles stabilized by proteins may may occur at the protein’s isoelectric point when the particle has zero net charge. Aggregation may be reduced bychanging the isoelectric point by conjugation of free amino groups with reducing sugars (Maillard reaction). Alternativ...

  16. Highly sensitive biosensors based on water-soluble conjugated polymers

    Institute of Scientific and Technical Information of China (English)

    XU Hui; WU Haiping; FAN Chunhai; LI Wenxin; ZHANG Zhizhou; HE Lin

    2004-01-01

    Conjugated, conductive polymers are a kind of important organic macromolecules, which has found applications in a variety of areas. The application of conjugated polymers in developing fluorescent biosensors represents the merge of polymer sciences and biological sciences. Conjugated polymers are very good light harvesters as well as fluorescent polymers, and they are also "molecular wires". Through elaborate designs, these important features, i.e. efficient light harvesting and electron/energy transfer, can be used as signal amplification in fluorescent biosensors. This might significantly improve the sensitivity of conjugated polymer-based biosensors. In this article, we reviewed the application of conjugated polymers, via either electron transfer or energy transfer, to detections of gene targets, antibodies or enzymes. We also reviewed recent efforts in conjugated polymer-based solid-state sensor designs as well as chip-based multiple target detection. Possible directions in this conjugated polymer-based biosensor area are also discussed.

  17. Application of optical phase conjugation to plasma diagnostics (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Jahoda, F.C.; Anderson, B.T.; Forman, P.R.; Weber, P.G.

    1985-05-01

    Several possibilities for plasma diagnostics provided by optical phase conjugation and, in particular, self-pumped phase conjugation in barium titanate (BaTiO/sub 3/) are discussed. These include placing a plasma within a dye laser cavity equipped with a phase conjugate mirror for intracavity absorption measurements, time differential refractometry with high spatial resolution, and simplified real-time holographic interferometry. The principles of phase conjugation with particular reference to photorefractive media and the special advantages of self-pumped phase conjugation are reviewed prior to the discussion of the applications. Distinctions are made in the applications between those for which photorefractive conjugators are essential and those for which they only offer experimental simplification relative to other types of phase conjugators.

  18. Sequential detection of multiple phase transitions in model biological membranes using a red-emitting conjugated polyelectrolyte.

    Science.gov (United States)

    Houston, Judith E; Kraft, Mario; Scherf, Ullrich; Evans, Rachel C

    2016-05-14

    The anionic conjugated polyelectrolyte, poly[3-(6-sulfothioatehexyl)thiophene] (P3Anionic), functions as a highly sensitive probe of membrane order, uniquely capable of sequentially detecting the three key phase transitions occurring within model phospholipid bilayers. The observed sensitivity is the result of charge-mediated, selective localisation of P3Anionic within the head-groups of the phospholipid bilayer. PMID:27098999

  19. Multistep Charge Method by Charge Arrays

    Science.gov (United States)

    Segami, Go; Kusawake, Hiroaki; Shimizu, Yasuhiro; Iwasa, Minoru; Kibe, Koichi

    2008-09-01

    We studied reduction of the size and weight of the Power Control Unit (PCU). In this study, we specifically examined the weight of the Battery Charge Regulator (BCR), which accounts for half of the PCU weight for a low earth orbit (LEO) satellite. We found a multistep charge method by charge arrays and adopted a similar method for GEO satellites, thereby enabling the BCR reduction. We found the possibility of reducing the size and weight of PCU through more detailed design than that for a conventional PCU.BCRC1R1batterySAPower Control UnitBCRC1R1batterySAPower UnitHowever, this method decreases the state of charge (SOC) of the battery. Battery tests, a battery simulator test, and numerical analysis were used to evaluate the SOC decrease. We also studied effects of this method on the battery lifetime. The multistep charge method by charge arrays enabled charging to the same level of SOC as the conventional constant current/ constant voltage (CC/CV) charge method for a LEO satellite.

  20. Fluctuations of general charge in soliton anti-soliton systems

    International Nuclear Information System (INIS)

    Full text: The interest in the investigation of non-integer charge has become stronger in quantum field theory since the original work of R.Jackiw and C.Rebbi [ R.Jackiw and C.Rebbi, Phys.Rev.D13,3398(1976)]. This charge conjugation symmetric (1+1)D model, with a soliton anti-soliton background, predicts e/2 as an eigenvalue of the charge operator and has been used to describe properties of polyacetylene. This interesting description was achieved by noting that the material consists in linear chains of carbon atoms, whose positions can be mapped in the background field. This fields suffer a breaking of symmetry in such a way that the new bound state is not symmetric but localized at the new soliton position, i.e., about 0,04 Ansgrongs from the original position. The concept of fractionary charge has been reinforced by showing that there are no charge fluctuations, which means that this is a good quantum number. These ideas opened a door for investigations in condensed matter using,as a tool,quantum field theory. Further experimental evidences for this effect have appeared recently and the discussion of fractionalization in (1+1) has been done also on the phenomenological sense by the authors of [E.Berg, Y.Oreg, E.-A.Kim, and F.von Oppen, Phys.Rev.Lett. 102,236402(2009)], who proposed a way to measure this kind of effect. It is very natural that variations of the original models predict a much richer spectrum of possibilities. The simplest generalization is to include breaking of charge conjugation in Jackiws first proposal, as was done by R.Jackiw and G.Semenoff [Phys.Rev.Lett. 50,439(1983)], in which general non-integer charges were obtained. J.Goldstone and F.Wilczek [Phys.Rev.Lett. 47,986(1981)] showed a general method for computing the charge and used to study the same problem in two and four dimensions. Until now, however, it is still missing an investigation on charge fluctuations within models without charge conjugations symmetry. To perform this

  1. Synthesis and properties of differently charged chemiluminescent acridinium ester labels.

    Science.gov (United States)

    Natrajan, Anand; Sharpe, David

    2013-02-14

    Chemiluminescent acridinium dimethylphenyl esters containing N-sulfopropyl groups in the acridinium ring are highly sensitive, hydrophilic labels that are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of a cationic surfactant. At physiological pH, N-sulfopropyl acridinium esters exist as water adducts that are commonly referred to as pseudobases. Pseudobase formation, which results from addition of water to the zwitterionic N-sulfopropyl acridinium ring, neutralizes the positive charge on the acridinium nitrogen and imparts a net negative charge to the label due to the sulfonate moiety. As a consequence, N-sulfopropyl acridinium ester conjugates of small molecule haptens as well as large molecules such as proteins gain negative charges at neutral pH. In the current study, we describe the synthesis and properties of two new hydrophilic acridinium dimethylphenyl ester labels where the net charge in the labels was altered. In one label, the structure of the hydrophilic N-alkyl group attached to the acridinium ring was changed so that the pseudobase of the label contains no net charge. In the second acridinium ester, two additional negative charges in the form of sulfopropyl groups were added to the acridinium ring to make this label's pseudobase strongly anionic. Chemiluminescence measurements of these labels, as well as their conjugates of an antibody with a neutral pI, indicate that acridinium ester charge while having a modest effect on emission kinetics has little influence on light output. However, our results demonstrate that acridinium ester charge can affect protein pI, apparent chemiluminescence stability and non-specific binding of protein conjugates to microparticles. These results emphasize the need for careful consideration of acridinium ester charge in order to optimize reagent stability and performance in immunoassays. In the current study, we observed that

  2. Time-resolved FRET and PCT in cationic conjugated polymer/dye-labeled DNA complex

    Science.gov (United States)

    Kim, Inhong; Kim, Jihoon; Kim, Bumjin; Kang, Mijeong; Woo, Han Young; Kyhm, Kwangseuk

    2011-12-01

    The energy transfer mechanism between cationic conjugated polyelectrolytes and a single stranded DNA labeled with fluorescein was investigated in terms of Förster resonance energy transfer (FRET) and photo-induced charge transfer (PCT) by time-resolved fluorescence. Both FRET and PCT rate efficiencies were obtained by phenomenological coupled rate equations, which are in excellent agreement with experiments. We found the total energy transfer in the complex is maximized as a consequence of FRET and PCT at an optimum distance 32.7Å.

  3. High-Permittivity Conjugated Polyelectrolyte Interlayers for High-Performance Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Kesters, Jurgen; Govaerts, Sanne; Pirotte, Geert; Drijkoningen, Jeroen; Chevrier, Michèle; Van den Brande, Niko; Liu, Xianjie; Fahlman, Mats; Van Mele, Bruno; Lutsen, Laurence; Vanderzande, Dirk; Manca, Jean; Clément, Sébastien; Von Hauff, Elizabeth; Maes, Wouter

    2016-03-16

    Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V characteristics of organic photovoltaics. Nevertheless, clear guidelines with respect to the structure of high-performance interlayers are still lacking. In this work, impedance spectroscopy is applied to probe the dielectric permittivity of a series of polythiophene-based CPEs. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is the diminishing affinity with the underlying photoactive layer. To balance these two effects, we found copolymer structures containing nonionic side chains to be beneficial. PMID:26927416

  4. Liquid Crystalline π-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group

    Directory of Open Access Journals (Sweden)

    Kohsuke Kawabata

    2009-01-01

    Full Text Available Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation of the main chain and side chain in the formation of a nematic main-chain/side-chain liquid crystal phase. The generation of polarons in the main chain as charge carriers during in-situ vapor doping of iodine is confirmed to increase with a doping progresses, exhibiting Dysonian paramagnetic behavior typical of conductive polymers.

  5. Electroluminescence from multilayer conjugated polymer devices: Spatial control of exciton formation and emission

    Science.gov (United States)

    Brown, A. R.; Greenham, N. C.; Burroughes, J. H.; Bradley, D. D. C.; Friend, R. H.; Burn, P. L.; Kraft, A.; Holmes, A. B.

    1992-11-01

    We have constructed electroluminescent diodes using several layers of conjugated polymers with differing band gaps; these provide a range of different colour light-emitting layers and can be used to control charge injection and transport. Poly(1,4-phenylenevinylene, PPV, and derivatives have been used, with indium/tin oxide as hole-injecting layer and calcium as electron-injecting contact layer. For this selection of materials, we show that the ordering of the polymer layers allows control of the colour of device emission. Emission can be produced in more than one layer.

  6. Effects of alkyl chain positioning on conjugated polymer microstructure and field-effect mobilities

    KAUST Repository

    Schroeder, Bob C.

    2015-07-02

    Solubilizing alkyl chains play a crucial role in the design of semiconducting polymers because they define the materials solubility and processability as well as both the crystallinity and solid-state microstructure. In this paper, we present a scarcely explored design approach by attaching the alkyl side chains on one side (cis-) or on both sides (trans-) of the conjugated backbone. We further investigate the effects of this structural modification on the solid-state properties of the polymers and on the charge-carrier mobilities in organic thin-film transistors. Copyright © Materials Research Society 2015

  7. Discrete modelling of bacterial conjugation dynamics

    CERN Document Server

    Goni-Moreno, Angel

    2012-01-01

    In bacterial populations, cells are able to cooperate in order to yield complex collective functionalities. Interest in population-level cellular behaviour is increasing, due to both our expanding knowledge of the underlying biological principles, and the growing range of possible applications for engineered microbial consortia. Researchers in the field of synthetic biology - the application of engineering principles to living systems - have, for example, recently shown how useful decision-making circuits may be distributed across a bacterial population. The ability of cells to interact through small signalling molecules (a mechanism known as it quorum sensing) is the basis for the majority of existing engineered systems. However, horizontal gene transfer (or conjugation) offers the possibility of cells exchanging messages (using DNA) that are much more information-rich. The potential of engineering this conjugation mechanism to suit specific goals will guide future developments in this area. Motivated by a l...

  8. Conjugate lateral eye movements: A second look

    OpenAIRE

    Charlton, S; Bakan, P.; Moretti, M. M.

    1989-01-01

    It has been suggested that conjugate lateral eye movements (CLEM) are related to cerebral lateralization. Two types of research have developed: studies examining individual differences (hemisphericity) and studies examining the type of questions used to elicit eye movements (hemispheric specialization). in a 1978 review, Ehrlichman and Weinberger questioned the notion that CLEM is related to cerebral lateralization, particularly with regard to individual differences. However, since their revi...

  9. Conjugated Linoleic Acid: good or bad nutrient

    Directory of Open Access Journals (Sweden)

    Gonçalves Daniela C

    2010-10-01

    Full Text Available Abstract Conjugated linoleic acid (CLA is a class of 28 positional and geometric isomers of linoleic acid octadecadienoic.Currently, it has been described many benefits related to the supplementation of CLA in animals and humans, as in the treatment of cancer, oxidative stress, in atherosclerosis, in bone formation and composition in obesity, in diabetes and the immune system. However, our results show that, CLA appears to be not a good supplement in patients with cachexia.

  10. Development of a conjugate heat transfer solver

    OpenAIRE

    Al-Qubeissi, Mansour

    2013-01-01

    The current research study presents a numerical approach in modelling the conjugate heat transfer system of the gas-turbine rotating discs-cavities. The work was undertaken to understand such phenomena and, more specifically, to numerically investigate the thermal interactions in rotating discs-cavities. The developed solver is capable of dealing with complex heat transfer problems, such as unsteady three-dimensional compressible rotating-flows. The development was based on integrating...

  11. Spectral phase conjugation via extended phase matching

    OpenAIRE

    Tsang, Mankei

    2005-01-01

    It is shown that the copropagating three-wave-mixing parametric process, with appropriate type-II extended phase matching and pumped with a short second-harmonic pulse, can perform spectral phase conjugation and parametric amplification, which shows a threshold behavior analogous to backward wave oscillation. The process is also analyzed in the Heisenberg picture, which predicts a spontaneous parametric down conversion rate in agreement with the experimental result reported by Kuzucu et al. [...

  12. Functionalized conjugated polyelectrolytes design and biomedical applications

    CERN Document Server

    Wang, Shu

    2013-01-01

    Functionalized Conjugated Polyelectrolytes presents a comprehensive review of these polyelectrolytes and their biomedical applications. Basic aspects like molecular design and optoelectronic properties are covered in the first chapter. Emphasis is placed on the various applications including sensing (chemical and biological), disease diagnosis, cell imaging, drug/gene delivery and disease treatment. This book explores a multi-disciplinary topic of interest to researchers working in the fields of chemistry, materials, biology and medicine. It also offers an integrated perspective on both basic

  13. Solventless processing of conjugated polymers - a review

    OpenAIRE

    Brandão, Lúcia; Viana, Júlio; David G. Bucknall; Bernardo, Gabriel

    2014-01-01

    The molecular mobility of polymers in their solid or molten states allows their processing without the need for toxic, “non-friendly” solvents. In this work, the main features of solvent-free processing methods applied to conjugated polymers are reviewed taking into consideration that these materials are largely used in a broad range of (opto-)electronic applications, including organic field-effect transistors, polymer light-emitting diodes and polymer photovoltaic devices. This review addres...

  14. Synthesis of Nanogel-Protein Conjugates

    OpenAIRE

    Matsumoto, Nicholas M.; González-Toro, Daniella C.; Chacko, Reuben T.; Maynard, Heather D.; Thayumanavan, S.

    2013-01-01

    The covalent conjugation of bovine serum albumin (BSA) to disulfide cross-linked polymeric nanogels is reported. Polymeric nanogel precursors were synthesized via a reversible addition-fragmentation chain transfer (RAFT) random copolymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and pyridyl disulfide methacrylate (PDSMA). Reaction of the p(PEGMA-co-PDSMA) with dithiothreitol resulted in the formation of nanogels. PDSMA serves as both a crosslinking agent and a reactive...

  15. Metal-organic charge transfer can produce biradical states and is mediated by conical intersections

    OpenAIRE

    Tishchenko, Oksana; Li, Ruifang; Truhlar, Donald G.

    2010-01-01

    The present paper illustrates key features of charge transfer between calcium atoms and prototype conjugated hydrocarbons (ethylene, benzene, and coronene) as elucidated by electronic structure calculations. One- and two-electron charge transfer is controlled by two sequential conical intersections. The two lowest electronic states that undergo a conical intersection have closed-shell and open-shell dominant configurations correlating with the 4s2 and 4s13d1 states of Ca, respectively. Unlike...

  16. Charged sectors, spin and statistics in quantum field theory on curved spacetimes

    OpenAIRE

    D. Guido; R. Longo; Roberts, J. E.; Verch, R.

    1999-01-01

    The first part of this paper extends the Doplicher-Haag-Roberts theory of superselection sectors to quantum field theory on arbitrary globally hyperbolic spacetimes. The statistics of a superselection sector may be defined as in flat spacetime and each charge has a conjugate charge when the spacetime possesses non-compact Cauchy surfaces. In this case, the field net and the gauge group can be constructed as in Minkowski spacetime. The second part of this paper derives spin-statistics theorems...

  17. Cancer Chemopreventive Ability of Conjugated Linolenic Acids

    Directory of Open Access Journals (Sweden)

    Kazuo Miyashita

    2011-11-01

    Full Text Available Conjugated fatty acids (CFA have received increased interest because of their beneficial effects on human health, including preventing cancer development. Conjugated linoleic acids (CLA are such CFA, and have been reviewed extensively for their multiple biological activities. In contrast to other types of CFAs including CLA that are found at low concentrations (less than 1% in natural products, conjugated linolenic acids (CLN are the only CFAs that occur in higher quantities in natural products. Some plant seeds contain a considerably high concentration of CLN (30 to 70 wt% lipid. Our research group has screened CLN from different plant seed oils to determine their cancer chemopreventive ability. This review describes the physiological functions of CLN isomers that occur in certain plant seeds. CLN are able to induce apoptosis through decrease of Bcl-2 protein in certain human cancer cell lines, increase expression of peroxisome proliferator-activated receptor (PPAR-γ, and up-regulate gene expression of p53. Findings in our preclinical animal studies have indicated that feeding with CLN resulted in inhibition of colorectal tumorigenesis through modulation of apoptosis and expression of PPARγ and p53. In this review, we summarize chemopreventive efficacy of CLN against cancer development, especially colorectal cancer.

  18. Oligonucleotide conjugates - Candidates for gene silencing therapeutics.

    Science.gov (United States)

    Gooding, Matt; Malhotra, Meenakshi; Evans, James C; Darcy, Raphael; O'Driscoll, Caitriona M

    2016-10-01

    The potential therapeutic and diagnostic applications of oligonucleotides (ONs) have attracted great attention in recent years. The capability of ONs to selectively inhibit target genes through antisense and RNA interference mechanisms, without causing un-intended sideeffects has led them to be investigated for various biomedical applications, especially for the treatment of viral diseases and cancer. In recent years, many researchers have focused on enhancing the stability and target specificity of ONs by encapsulating/complexing them with polymers or lipid chains to formulate nanoparticles/nanocomplexes/micelles. Also, chemical modification of nucleic acids has emerged as an alternative to impart stability to ONs against nucleases and other degrading enzymes and proteins found in blood. In addition to chemically modifying the nucleic acids directly, another strategy that has emerged, involves conjugating polymers/peptide/aptamers/antibodies/proteins, preferably to the sense strand (3'end) of siRNAs. Conjugation to the siRNA not only enhances the stability and targeting specificity of the siRNA, but also allows for the development of self-administering siRNA formulations, with a much smaller size than what is usually observed for nanoparticle (∼200nm). This review concentrates mainly on approaches and studies involving ON-conjugates for biomedical applications. PMID:27521696

  19. Structural investigation of PEG-fibrinogen conjugates.

    Science.gov (United States)

    Frisman, Ilya; Orbach, Ron; Seliktar, Dror; Bianco-Peled, Havazelet

    2010-01-01

    Controllable bio-synthetic polymeric hydrogels made from fibrinogen-poly(ethylene glycol) adducts have been successfully employed in tissue engineering. The structural consequences of PEG conjugation to fibrinogen (i.e., PEGylation) in such a hydrogel network are not fully understood. The current investigation details the structural alterations caused to the reduced fibrinogen polypeptides by the covalent attachment of linear or branched PEG chains. The structure of PEGylated fibrinogen polypeptides were comprehensively characterized using small angle X-ray scattering, light scattering, and cryo-transmission electron microscopy. These characterizations concur that the bio-synthetic hybrids self-assemble into elongated objects, having a protein core of about 50 A in diameter decorated with multiple PEG chains. Conjugates with branched PEG chains were shorter, and have lower average molecular weight compared to conjugates with linear chains. The diameter of the protein core of both samples was similar, suggesting a tail-to-head aggregation of the PEGylated fibrinogen polypeptide. A more complete understanding of this unique structural arrangement can provide further insight into the full extent of biofunctional accessibility in a biomaterial that combines the advantages of synthetic polymers with bioactive proteins. PMID:19693654

  20. Synthesis of Nanogel-Protein Conjugates.

    Science.gov (United States)

    Matsumoto, Nicholas M; González-Toro, Daniella C; Chacko, Reuben T; Maynard, Heather D; Thayumanavan, S

    2013-04-21

    The covalent conjugation of bovine serum albumin (BSA) to disulfide cross-linked polymeric nanogels is reported. Polymeric nanogel precursors were synthesized via a reversible addition-fragmentation chain transfer (RAFT) random copolymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and pyridyl disulfide methacrylate (PDSMA). Reaction of the p(PEGMA-co-PDSMA) with dithiothreitol resulted in the formation of nanogels. PDSMA serves as both a crosslinking agent and a reactive handle for the surface modification of the nanogels. Lipophilic dye, DiI, was sequestered within the nanogels by performing the crosslinking reaction in the presence of the hydrophobic molecule. Thiol-enriched BSA was conjugated to nanogels loaded with DiI via a disulfide reaction between the BSA and the surface exposed nanogel pyridyl disulfides. Conjugation was confirmed by fast protein liquid chromatography, dynamic light scattering, and agarose and polyacrylamide gel electrophoresis. We expect that this methodology is generally applicable to the preparation of nanogel-protein therapeutics. PMID:24761162

  1. Conjugation, characterization and toxicity of lipophosphoglycan-polyacrylic acid conjugate for vaccination against leishmaniasis.

    Science.gov (United States)

    Topuzogullari, Murat; Cakir Koc, Rabia; Dincer Isoglu, Sevil; Bagirova, Melahat; Akdeste, Zeynep; Elcicek, Serhat; Oztel, Olga N; Yesilkir Baydar, Serap; Canim Ates, Sezen; Allahverdiyev, Adil M

    2013-01-01

    Research on the conjugates of synthetic polyelectrolytes with antigenic molecules, such as proteins, peptides, or carbohydrates, is an attractive area due to their highly immunogenic character in comparison to classical adjuvants. For example, polyacrylic acid (PAA) is a weak polyelectrolyte and has been used in several biomedical applications such as immunological studies, drug delivery, and enzyme immobilization. However, to our knowledge, there are no studies that document immune-stimulant properties of PAA in Leishmania infection. Therefore, we aimed to develop a potential vaccine candidate against leishmaniasis by covalently conjugating PAA with an immunologically vital molecule of lipophosphoglycan (LPG) found in Leishmania parasites. In the study, LPG and PAA were conjugated by a multi-step procedure, and final products were analyzed with GPC and MALDI-TOF MS techniques. In cytotoxicity experiments, LPG-PAA conjugates did not indicate toxic effects on L929 and J774 murine macrophage cells. We assume that LPG-PAA conjugate can be a potential vaccine candidate, and will be immunologically characterized in further studies to prove its potential. PMID:23731716

  2. Hybrid solar cells based on colloidal nanocrystals and conjugated polymers

    International Nuclear Information System (INIS)

    In this study, monodispersed colloidal titanium dioxide (TiO2) was synthesized and applied with poly(3-octylthiophene-2,5-diyl) (P3OT), phenyl-C61-butyric acid methyl ester (PCBM), poly(3,4-ethylene dioxythiophene) (PEDOT), and poly(styrenesulfonate (PSS) to fabricate an aluminum/calcium/P3OT:PCBM:TiO2/PEDOT:PSS/indium tin oxide hybrid solar cell using spin coating and evaporation deposition. The effects of the TiO2 content and annealing temperature on cell performances were investigated. The results showed that optimization of the TiO2 content (15 wt.%) and annealing temperature (150 °C) effectively enhanced the performance of the hybrid solar cells. The PCBM and TiO2 absorbed more light photons in the P3OT:PCBM:TiO2 active layer. The charge transfer in the P3OT:PCBM:TiO2 active layer was more efficient, increasing the amount of photoluminescence quenching. The increased active layer surface roughness reduced the charge-transport distance and enhanced the internal light scattering and light absorption. The best values for the open circuit voltage, short-circuit current density, fill factor, and efficiency for the prepared hybrid solar cell were 0.61 V, 9.50 mA/cm2, 34.46%, and 2.09%, respectively. - Highlights: • Solar cell based on titania and conjugated polymer was fabricated. • Optimal titania content and annealing temperature were investigated. • Solar cell with 2.09% efficiency was obtained

  3. On Dust Charging Equation

    OpenAIRE

    Tsintsadze, Nodar L.; Tsintsadze, Levan N.

    2008-01-01

    A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. A problem of linear fluctuations of charges on the surface of the dust grain is discussed.

  4. Dual E1 activation systems for ubiquitin differentially regulate E2 enzyme charging.

    Science.gov (United States)

    Jin, Jianping; Li, Xue; Gygi, Steven P; Harper, J Wade

    2007-06-28

    Modification of proteins with ubiquitin or ubiquitin-like proteins (UBLs) by means of an E1-E2-E3 cascade controls many signalling networks. Ubiquitin conjugation involves adenylation and thioesterification of the carboxy-terminal carboxylate of ubiquitin by the E1-activating enzyme Ube1 (Uba1 in yeast), followed by ubiquitin transfer to an E2-conjugating enzyme through a transthiolation reaction. Charged E2s function with E3s to ubiquitinate substrates. It is currently thought that Ube1/Uba1 is the sole E1 for charging of E2s with ubiquitin in animals and fungi. Here we identify a divergent E1 in vertebrates and sea urchin, Uba6, which specifically activates ubiquitin but not other UBLs in vitro and in vivo. Human Uba6 and Ube1 have distinct preferences for E2 charging in vitro, and their specificity depends in part on their C-terminal ubiquitin-fold domains, which recruit E2s. In tissue culture cells, Uba6 is required for charging a previously uncharacterized Uba6-specific E2 (Use1), whereas Ube1 is required for charging the cell-cycle E2s Cdc34A and Cdc34B. Our data reveal unexpected complexity in the pathways that control the conjugation of ubiquitin, in which dual E1s orchestrate the charging of distinct cohorts of E2s. PMID:17597759

  5. Solution-processed organic trilayer solar cells incorporating conjugated polyelectrolytes

    Science.gov (United States)

    Cha, Myoung Joo; Seo, Jung Hwa

    2016-01-01

    We report solution-processed organic trilayer solar cells consisting of a bottom poly(3-hexylthiophene) (P3HT) layer, a conjugated polyelectrolyte (CPE) interlayer and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) top layer, wherein the CPE exists as an interlayer within the donor-acceptor junction. The influence of interlayer thickness on device properties was investigated, as well as the behavior of molecular dipoles in the trilayer solar cells when influenced by external electrical stimuli. We found that incorporation of an interlayer which is too thick results in decreased performance due to reduced short-circuit current (JSC), open-circuit voltage (VOC), and fill factor (FF). However the VOC is found to increase significantly when a thin CPE layer is used in conjunction with an external electric field. These results provide an experimental approach to probe the influence of interfacial dipoles on the solar cell parameters and behavior of charge separating organic donor/acceptor junctions, yielding fundamental information about the influence of electrical dipoles on the donor/acceptor interface in organic solar cells.

  6. Induced Charge Capacitive Deionization

    OpenAIRE

    Rubin, S.; Suss, M. E.; Biesheuvel, P. M.; Bercovici, M.

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, ...

  7. Primitive Virtual Negative Charge

    OpenAIRE

    Kim, Kiyoung

    2008-01-01

    Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction...

  8. Picosecond phase conjugation in two-photon absorption in poly-di-acetylenes

    International Nuclear Information System (INIS)

    Poly-di-acetylenes exhibit a large two-photon absorption at 1064 nm wavelength. Its different effects on phase-conjugate nonlinearity are described in the framework of picosecond experiments. In solutions, gels, and films (optically thin media), third-order susceptibility appears as an increasing intensity dependent function. Phase measurements by nonlinear interferometry with the substrate or with the solvent are compared with predictions of a resonantly driven three level system. Phase-conjugate response exhibits a multi-exponential decay. Polarization symmetries analysis shows a one-dimensional effect. Study under strong static electric field action reveals that we face charged species bound to photoconductive polymer chains. In PTS single crystals (optically thick media), response saturates and cancels at high light intensity. This is well accounted for by propagation equations solved in large two-photon absorption conditions. The effect is exploited in a phase conjugation experiment under external optical pump excitation. We thus demonstrate that enhanced nonlinearity is a two-photon absorption relayed and amplified by mid-gap absorbing species which have been created by this two-photon absorption. We formally face a four-photon absorption described by a positive imaginary seventh-order non-linearity. (author)

  9. Rational Design of Porous Conjugated Polymers and Roles of Residual Palladium for Photocatalytic Hydrogen Production.

    Science.gov (United States)

    Li, Lianwei; Cai, Zhengxu; Wu, Qinghe; Lo, Wai-Yip; Zhang, Na; Chen, Lin X; Yu, Luping

    2016-06-22

    Developing highly efficient photocatalyts for water splitting is one of the grand challenges in solar energy conversion. Here, we report the rational design and synthesis of porous conjugated polymer (PCP) that photocatalytically generates hydrogen from water splitting. The design mimics natural photosynthetics systems with conjugated polymer component to harvest photons and the transition metal part to facilitate catalytic activities. A series of PCPs have been synthesized with different light harvesting chromophores and transition metal binding bipyridyl (bpy) sites. The photocatalytic activity of these bpy-containing PCPs can be greatly enhanced due to the improved light absorption, better wettability, local ordering structure, and the improved charge separation process. The PCP made of strong and fully conjugated donor chromophore DBD (M4) shows the highest hydrogen production rate at ∼33 μmol/h. The results indicate that copolymerization between a strong electron donor and weak electron acceptor into the same polymer chain is a useful strategy for developing efficient photocatalysts. This study also reveals that the residual palladium in the PCP networks plays a key role for the catalytic performance. The hydrogen generation activity of PCP photocatalyst can be further enhanced to 164 μmol/h with an apparent quantum yield of 1.8% at 350 nm by loading 2 wt % of extra platinum cocatalyst. PMID:27254306

  10. Random Conjugated Copolymers with Panchromatic Absorption for High-Efficiency Polymer Solar Cells

    Science.gov (United States)

    Jung, Jae Woong; Jo, Won Ho

    2013-03-01

    One of the most important issues for polymer solar cells (PSCs) is to develop conjugated polymers with broad light absorption, high mobility and appropriate orientation to provide effective pathways to electrode. Particularly, the broad light absorption of the polymer is important to enhance the power conversion efficiency because the limited absorption leads to low current in comparison with other inorganic-based solar cells. A fascinating approach to extend light absorption is the synthesis of copolymers composed of several chromophores. Among various building blocks, diketopyrrolo[3,4-c]pyrrole (DPP) and 6,6'-[3,3']biindolylidene-2,2'-dione (isoindigo) have attracted much interest since they are easily accessible and exhibit promising optoelectronic properties. Here, we report random conjugated copolymers consisting of DPP and isoindigo as co-electron acceptor of donor-acceptor conjugated polymer. The random copolymers exhibited not only broad light absorption but also low-lying HOMO levels. Also, the predominant face-on orientation of the copolymers is beneficial for vertical charge transport in PSCs. The combination of excellent optoelectrical properties and favorable molecular conformation makes copolymers promising candidate for active material in high performance PSCs.

  11. Charge exchange system

    Science.gov (United States)

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  12. Ultrafast photophysics of pi-conjugated polymers and polythiophene/fullerene blends for organic photovoltaic applications

    Science.gov (United States)

    Singh, Sanjeev

    The present work reports studies of the ultrafast photoexcitations in various pristine n-conjugated polymers as well as compounds of polythiophene/fullerene blends, which act as the active layer of donor/acceptor in organic photovoltaic applications. The main technique used is the ultrafast (˜150 fs) transient photomodulation (PM) spectroscopy in the range of 0.25 to 2.5 eV using two different laser systems. In addition, two-photon-absorption and electroabsorption have also been complementary used. In organic photovoltaic studies, two different donor polymers namely, Regio-Regular-poly(3-hexylthiophene) (RR-P3HT) that forms lamellae, and Regio-Random-poly(3-hexylthiophene) (RRa-P3HT) that forms lamellae with lesser extent have been compared. The transient PM measurement of the most efficient RR-P3HT/fullerene blend shows that the decay of exciton does not result in the generation of polarons in the donor and acceptor materials, as assumed by the present model of charge dissociation in photovoltaic devices. On the contrary, the decay of exciton fits very well to the build-up of charge-transfer (CT) state in the fullerene phase, which indicates the migration of the photoexcited exciton in the polymer phase to the fullerene nano-domains. The transient PM measurement of RRa-P3HT/fullerene blend, which does not form phase-separated nano-domains, shows the formation of a CT state at the interface following by ultrafast geminate recombination. The transient PM measurement of poly(phenylene-vinylene) (PPV) derivatives show that in 2-methoxy-5-(2'-ethylhexyloxy) PPV (MEH-PPV) film there are two kinds of primary photoexcitations, namely, intrachain exciton and excimer, but only intra-chain exciton in other PPV derivative polymers. Furthermore the high-pressure study of MEHPPV film shows two kinds of polymer chain orders: isolated-chains and closely packed-chains. The high pressure mainly affects photoexcited excimers in the closely packed-chains. In contrast there is no

  13. Space Charge Effects

    CERN Document Server

    Ferrario, M; Palumbo, L

    2014-01-01

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

  14. Electroluminescence from multilayer conjugated polymer devices--spatial control of exciton formation and emission

    Science.gov (United States)

    Greenham, Neil C.; Brown, Adam R.; Burroughes, Jeremy H.; Bradley, Donal D. C.; Friend, Richard H.; Burn, Paul L.; Kraft, Arno; Holmes, Andrew B.

    1993-08-01

    We have constructed electroluminescent diodes using several layers of conjugated polymers with differing energy gaps; these provide a range of different color light-emitting layers and can be used to control charge injection and transport. Poly(1,4-phenylenevinylene), PPV, and derivatives have been used, with indium tin oxide as hole-injecting electrode and calcium as electron-injecting electrode. For this selection of materials, we show that the sequence of the polymer layers allows control of the color of device emission. Emission from more than one layer can be produced simultaneously. The position and breadth of the light-emitting region of the device provides information about the mechanisms of charge transport and of exciton motion. Various models for multilayer emission are discussed in the paper.

  15. Glutaraldehyde mediated conjugation of amino-coated magnetic nanoparticles with albumin protein for nanothermotherapy.

    Science.gov (United States)

    Zhao, Lingyun; Yang, Bing; Dai, Xiaochen; Wang, Xiaowen; Gao, Fuping; Zhang, Xiaodong; Tang, Jintian

    2010-11-01

    A novel bioconjugation of amino saline capped Fe3O4 magnetic nanoparticles (MNPs) with bovine serum albumin (BSA) was developed by applying glutaraldehyde as activator. Briefly, Fe3O4 MNs were synthesized by the chemical co-precipitation method. Surface modification of the prepared MNPs was performed by employing amino saline as the coating agent. Glutaraldehyde was further applied as an activation agent through which BSA was conjugated to the amino-coated MNPs. The structure of the BSA-MNs was confirmed by FTIR analysis. Physico-chemical characterizations of the BSA-MNPs, such as surface morphology, surface charge and magnetic properties were investigated by Transmission Electron Microscopy (TEM), zeta-Potential and Vibrating Sample Magnetometer (VSM), etc. Magnetic inductive heating characteristics of the BSA-MNPs were analyzed by exposing the MNPs suspension (magnetic fluid) under alternative magnetic field (AMF). The results demonstrate that BSA was successfully conjugated with amino-coated MNs mediated through glutaraldehyde activation. The nanoparticles were spherical shaped with approximately 10 nm diameter. Possessing ideal magnetic inductive heating characteristics, which can generate very rapid and efficient heating while upon AMF exposure, BSA-MNPs can be applied as a novel candidature for magnetic nanothermotherapy for cancer treatment. In vitro cytotoxicity study on the human hepatocellular liver carcinoma cells (HepG-2) indicates that BSA-MNP is an efficient agent for cancer nanothermotherapy with satisfied biocompatibility, as rare cytotoxicity was observed in the absence of AMF. Moreover, our investigation provides a methodology for fabrication protein conjugated MNPs, for instance monoclonal antibody conjugated MNPs for targeting cancer nanothermotherapy. PMID:21137877

  16. Cellular delivery of shRNA using aptamer-conjugated PLL-alkyl-PEI nanoparticles.

    Science.gov (United States)

    Askarian, Saeedeh; Abnous, Khalil; Taghavi, Sahar; Oskuee, Reza Kazemi; Ramezani, Mohammad

    2015-12-01

    Introduction of an efficient gene delivery vector is still the main challenge of gene therapy. Both polyethylenimine (PEI) and poly(l-lysine) (PLL) comprise disadvantages which limited their application. To explore whether their deficiencies could be compensated by preparing copolymers consisting of both PLL and PEI, we generated several combinations of PLL-alkyl-PEI copolymers conjugated to aptamer and evaluated their both gene delivery efficiency and down-regulation of Bcl-XL, an anti-apoptotic gene, in lung cancer cell line. PLL was conjugated to either 10% or 50% of PEI by grafting different percentages of PEI to alkylated-PLL as core. The properties of modified polymers including size, surface charge density, DNA condensation ability, buffering capacity and cytotoxicity were evaluated. According to transfection results, aptamer conjugated PLL-alkyl-10%-PEI (PLPE8%) was selected for further gene silencing study by plasmid shRNA. Decrease in Bcl-XL gene expression was estimated by both RT-PCR and western-blot experiments. The obtained results revealed that the new copolymers had appropriate nano-scale size (117-128 nm) even after aptamer conjugation (168-183 nm). Moreover, they exhibited increased transfection efficiencies by up to 1.8-5 folds and acceptable cytotoxicity. The apoptosis was induced in transfected cells by shRNA-aptamer-copolymer due to the down-regulation of mRNA and protein levels. This study suggested a new vector for targeted non-viral gene delivery with high transfection efficiency in lung cancer or pulmonary systems. PMID:26433348

  17. Design, synthesis, characterization and study of novel conjugated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.

    1997-06-24

    After introducing the subject of conjugated polymers, the thesis has three sections each containing a literature survey, results and discussion, conclusions, and experimental methods on the following: synthesis, characterization of electroluminescent polymers containing conjugated aryl, olefinic, thiophene and acetylenic units and their studies for use in light-emitting diodes; synthesis, characterization and study of conjugated polymers containing silole unit in the main chain; and synthesis, characterization and study of silicon-bridged and butadiene-linked polythiophenes.

  18. Extended affine Weyl groups: Presentation by conjugation via integral collection

    OpenAIRE

    Azam, Saeid; Shahsanaei, Valiollah

    2009-01-01

    We give several necessary and sufficient conditions for the existence of {\\it the presentation by conjugation} for a non-simply laced extended affine Weyl group. We invent a computational tool by which one can determine simply the existence of the presentation by conjugation for an extended affine Weyl group. As an application, we determine the existence of the presentation by conjugation for a large class of extended affine Weyl groups.

  19. Genetic drift suppresses bacterial conjugation in spatially structured populations

    OpenAIRE

    Freese, Peter D.; Korolev, Kirill S.; Jiménez, José I.; Chen, Irene A.

    2014-01-01

    Conjugation is the primary mechanism of horizontal gene transfer that spreads antibiotic resistance among bacteria. Although conjugation normally occurs in surface-associated growth (e.g., biofilms), it has been traditionally studied in well-mixed liquid cultures lacking spatial structure, which is known to affect many evolutionary and ecological processes. Here we visualize spatial patterns of gene transfer mediated by F plasmid conjugation in a colony of Escherichia coli growing on solid ag...

  20. Spectral phase conjugation with cross-phase modulation compensation

    OpenAIRE

    Tsang, Mankei; Psaltis, Demetri

    2004-01-01

    Spectral phase conjugation with short pump pulses in a third-order nonlinear material is analyzed in depth. It is shown that if signal amplification is considered, the conversion efficiency can be significantly higher than previously considered, while the spectral phase conjugation operation remains accurate. A novel method of compensating for cross-phase modulation, the main parasitic effect, is also proposed. The validity of our theory and the performance of the spectral phase conjugation s...

  1. Dispersion and nonlinearity compensation by spectral phase conjugation

    OpenAIRE

    Tsang, Mankei; Psaltis, Demetri

    2003-01-01

    We propose the use of spectral phase conjugation to compensate for dispersion of all orders, self-phase modulation, and self-steepening of an optical pulse in a fiber. Although this method cannot compensate for loss and intrapulse Raman scattering, it is superior to the previously suggested midway temporal phase conjugation method if high-order dispersion is a main source of distortion. The reshaping performance of our proposed scheme and a combined temporal and spectral phase conjugation sch...

  2. Evolution of Conjugation and Type IV Secretion Systems

    OpenAIRE

    Guglielmini J.; De La Cruz F.; Rocha E.P.C.

    2013-01-01

    Genetic exchange by conjugation is responsible for the spread of resistance, virulence, and social traits among prokaryotes. Recent works unraveled the functioning of the underlying type IV secretion systems (T4SS) and its distribution and recruitment for other biological processes (exaptation), notably pathogenesis. We analyzed the phylogeny of key conjugation proteins to infer the evolutionary history of conjugation and T4SS. We show that single-stranded DNA (ssDNA) and double-stranded DNA ...

  3. Social behavior and decision making in bacterial conjugation

    OpenAIRE

    Koraimann, Günther; Wagner, Maria A.

    2014-01-01

    Bacteria frequently acquire novel genes by horizontal gene transfer (HGT). HGT through the process of bacterial conjugation is highly efficient and depends on the presence of conjugative plasmids (CPs) or integrated conjugative elements (ICEs) that provide the necessary genes for DNA transmission. This review focuses on recent advancements in our understanding of ssDNA transfer systems and regulatory networks ensuring timely and spatially controlled DNA transfer (tra) gene expression. As will...

  4. Conjugative type IV secretion systems in Gram-positive bacteria

    OpenAIRE

    Goessweiner-Mohr, Nikolaus; Arends, Karsten; Keller, Walter; Grohmann, Elisabeth

    2013-01-01

    Bacterial conjugation presents the most important means to spread antibiotic resistance and virulence factors among closely and distantly related bacteria. Conjugative plasmids are the mobile genetic elements mainly responsible for this task. All the genetic information required for the horizontal transmission is encoded on the conjugative plasmids themselves. Two distinct concepts for horizontal plasmid transfer in Gram-positive bacteria exist, the most prominent one transports single strand...

  5. Conjugative Plasmid Transfer in Gram-Positive Bacteria

    OpenAIRE

    Grohmann, Elisabeth; Muth, Günther; Espinosa, Manuel

    2003-01-01

    Conjugative transfer of bacterial plasmids is the most efficient way of horizontal gene spread, and it is therefore considered one of the major reasons for the increase in the number of bacteria exhibiting multiple-antibiotic resistance. Thus, conjugation and spread of antibiotic resistance represents a severe problem in antibiotic treatment, especially of immunosuppressed patients and in intensive care units. While conjugation in gram-negative bacteria has been studied in great detail over t...

  6. Enterobacterial common antigen-tetanus toxoid conjugate as immunogen.

    OpenAIRE

    Lugowski, C; Kułakowska, M; Romanowska, E

    1983-01-01

    The methods of limited periodate oxidation and reductive amination were used to obtain covalently linked enterobacterial common antigen (ECA) with tetanus toxoid. This procedure is simple and gives a good yield of the conjugate with high ECA content (molecular ratio of ECA to tetanus toxoid, 6:1). The ECA-tetanus toxoid conjugate is immunogenic in rabbits, in contrast to free ECA or a mixture of ECA with proteins. This conjugate produces high levels of ECA-specific immunoglobulin G antibodies...

  7. Polylactide Conjugates of Camptothecin with Different Drug Release Abilities

    OpenAIRE

    Ewa Oledzka; Paweł Horeglad; Zuzanna Gruszczyńska; Andrzej Plichta; Grzegorz Nałęcz-Jawecki; Marcin Sobczak

    2014-01-01

    Camptothecin-polylactide conjugates (CMPT-PLA) were synthesized by covalent incorporation of CMPT into PLA of different microstructure, i.e., atactic PLA and atactic-block-isotactically enriched PLA (Pm = 0.79) via urethane bonds. The kinetic release of CPMT from CMPT-PLA conjugates, tested in vitro under different conditions, is possible in both cases and notably, strongly dependent on PLA microstructure. It shows that release properties of drug-PLA conjugates can be tailored by controlled ...

  8. Preparation and characterization of microspheres of albumin-heparin conjugates

    OpenAIRE

    Kwon, Glen S.; Bae, You Han; Kim, Sung Wan; Cremers, Harry; Feijen, Jan

    1991-01-01

    Albumin-heparin microspheres have been prepared as a new drug carrier. A soluble albumin-heparin conjugate was synthesized by forming amide bonds between human serum albumin and heparin. After purification the albumin-heparin conjugate was crosslinked in a water-in-oil emulsion to form albumin-heparin microspheres. The composition of the conjugate was determined by amino acid analysis. The swelling properties of albumin-heparin microspheres were investigated as a function of pH and ionic stre...

  9. Goat serums for fluorescent antibody conjugates to chlamydial antigens.

    OpenAIRE

    Tessler, J.

    1984-01-01

    Serums from goats hyperimmunized with Chlamydia psittaci consistently produce antichlamydial fluorescent antibody conjugate of high titer. The titer of the fluorescent antibody conjugate prepared from a given serum correlated well with the titer obtained by agar gel precipitin, but not with the complement fixation. The agar gel precipitin test can be used to predict whether a given serum is satisfactory for use in production of a conjugate for direct fluorescent antibody tests. Serums with an...

  10. Mobile Charge Generation Dynamics in P3HT:PCBM Observed by Time-Resolved Terahertz Spectroscopy

    DEFF Research Database (Denmark)

    Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

    2012-01-01

    Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

  11. Sources and Bioactive Properties of Conjugated Dietary Fatty Acids.

    Science.gov (United States)

    Hennessy, Alan A; Ross, Paul R; Fitzgerald, Gerald F; Stanton, Catherine

    2016-04-01

    The group of conjugated fatty acids known as conjugated linoleic acid (CLA) isomers have been extensively studied with regard to their bioactive potential in treating some of the most prominent human health malignancies. However, CLA isomers are not the only group of potentially bioactive conjugated fatty acids currently undergoing study. In this regard, isomers of conjugated α-linolenic acid, conjugated nonadecadienoic acid and conjugated eicosapentaenoic acid, to name but a few, have undergone experimental assessment. These studies have indicated many of these conjugated fatty acid isomers commonly possess anti-carcinogenic, anti-adipogenic, anti-inflammatory and immune modulating properties, a number of which will be discussed in this review. The mechanisms through which these bioactivities are mediated have not yet been fully elucidated. However, existing evidence indicates that these fatty acids may play a role in modulating the expression of several oncogenes, cell cycle regulators, and genes associated with energy metabolism. Despite such bioactive potential, interest in these conjugated fatty acids has remained low relative to the CLA isomers. This may be partly attributed to the relatively recent emergence of these fatty acids as bioactives, but also due to a lack of awareness regarding sources from which they can be produced. In this review, we will also highlight the common sources of these conjugated fatty acids, including plants, algae, microbes and chemosynthesis. PMID:26968402

  12. A class of globally convergent conjugate gradient methods

    Institute of Scientific and Technical Information of China (English)

    DAI; Yuhong(戴彧虹); YUAN; Yaxiang(袁亚湘)

    2003-01-01

    Conjugate gradient methods are very important ones for solving nonlinear optimization problems,especially for large scale problems. However, unlike quasi-Newton methods, conjugate gradient methods wereusually analyzed individually. In this paper, we propose a class of conjugate gradient methods, which can beregarded as some kind of convex combination of the Fletcher-Reeves method and the method proposed byDai et al. To analyze this class of methods, we introduce some unified tools that concern a general methodwith the scalarβk having the form of φk/φk-1. Consequently, the class of conjugate gradient methods canuniformly be analyzed.

  13. Helically assembled π-conjugated polymers with circularly polarized luminescence

    International Nuclear Information System (INIS)

    We review the recent progress in the field of helically assembled π-conjugated polymers, focusing on aromatic conjugated polymers with interchain helical π-stacking that exhibit circularly polarized luminescence (CPL). In Part 1, we discuss optically active polymers with white-colored CPL and the amplification of the circular polarization through liquid crystallinity. In Part 2, we focus on the stimuli-responsive CPL that results from changes in the conformation and aggregation state of π-conjugated molecules and polymers. In Part 3, we discuss the self-assembly of achiral cationic π-conjugated polymers into circularly polarized luminescent supramolecular nanostructures with the aid of other chiral molecules. (review)

  14. Conjugation by Mosquito Pathogenic Strains of Bacillus sphaericus

    OpenAIRE

    Correa Margarita; Yousten Allan A

    1997-01-01

    A mosquito pathogenic strain of Bacillus sphaericus carried out the conjugal transfer of plasmid pAMß1 to other strains of its own and two other serotypes. However, it was unable to conjugate with mosquito pathogens from three other serotypes, with B. sphaericus of other DNA homology groups or with three other species of Bacillus. Conjugation frequency was highest with a strain having an altered surface layer (S layer). Conjugal transfer of pAMß1 was not detected in mosquito larval cadavers. ...

  15. Quantitative clinical uptake measurements using conjugate counting

    International Nuclear Information System (INIS)

    While the use of conjugate counting for determination of organ uptake in human subjects has been extensively described, in the present study the determination of the organ uptake of ortho-iodohippurate presented several opportunities for validation of the in vivo counting data. Ortho-iodohippurate is distributed in the extracellular space, is largely extracted on each pass through the kidneys, and is not significantly deiodinated in vivo. Thus, the kidney uptake rate should be proportional to the blood level, the appearance rate of activity in the bladder is equal to the disappearance rate from the kidneys, and direct measurement of activity in the urine after voiding provides an internal standard for imaging measurements of bladder activity. Since the activity levels in the kidneys, bladder, and remainder of the body changed fairly rapidly, especially in the first 20 to 30 minutes following injection, posterior images of the trunk including kidneys and bladder were obtained continuously using a gamma camera fitted with a diverging collimator for 30 minutes and then at intervals for several hours. Simultaneous conjugate counting determinations were made using a whole body scanning system previously described at these meetings. Imaging data corrected for decay and adjacent background were fitted by least squares methods to curves representing a sum of exponentials, and the curves were normalized to the conjugate uptake measurements. The uptake curves of the kidneys and bladder matched well with the direct measurements of the urinary excretion. Data were collected in 16 normal subjects, and the estimated absorbed dose was calculated for the kidneys, the bladder and the remainder of the body for seven radioisotopes of iodine. 4 references, 6 figures, 2 tables

  16. Multicellular computing using conjugation for wiring.

    Directory of Open Access Journals (Sweden)

    Angel Goñi-Moreno

    Full Text Available Recent efforts in synthetic biology have focussed on the implementation of logical functions within living cells. One aim is to facilitate both internal "re-programming" and external control of cells, with potential applications in a wide range of domains. However, fundamental limitations on the degree to which single cells may be re-engineered have led to a growth of interest in multicellular systems, in which a "computation" is distributed over a number of different cell types, in a manner analogous to modern computer networks. Within this model, individual cell type perform specific sub-tasks, the results of which are then communicated to other cell types for further processing. The manner in which outputs are communicated is therefore of great significance to the overall success of such a scheme. Previous experiments in distributed cellular computation have used global communication schemes, such as quorum sensing (QS, to implement the "wiring" between cell types. While useful, this method lacks specificity, and limits the amount of information that may be transferred at any one time. We propose an alternative scheme, based on specific cell-cell conjugation. This mechanism allows for the direct transfer of genetic information between bacteria, via circular DNA strands known as plasmids. We design a multi-cellular population that is able to compute, in a distributed fashion, a Boolean XOR function. Through this, we describe a general scheme for distributed logic that works by mixing different strains in a single population; this constitutes an important advantage of our novel approach. Importantly, the amount of genetic information exchanged through conjugation is significantly higher than the amount possible through QS-based communication. We provide full computational modelling and simulation results, using deterministic, stochastic and spatially-explicit methods. These simulations explore the behaviour of one possible conjugation

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

    KAUST Repository

    Lima, Igo T.

    2014-01-01

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

  18. A pH-sensitive binary drug delivery system based on poly(caprolactone)-heparin conjugates.

    Science.gov (United States)

    Ye, Lin; Gao, Zemin; Zhou, Yu; Yin, Xuan; Zhang, Xinpeng; Zhang, Aiying; Feng, Zengguo

    2014-03-01

    PCL-heparin conjugates were synthesized by coupling mono-hydroxyl terminated PCL (Mn = 2000-10000 g/mol) with heparin via EDC/NHS chemistry. The conjugates enabled to self-assemble into the core-shell nanoparticles in around 100 nm diameter to load binary anti-cancer drugs. Lipophilic and neutral paclitaxel (PTX) was first encapsulated in the core, and then hydrophilic and positive charged doxorubicin (DOX) was incorporated into the negative charged shell of PTX loaded nanoparticles via the electrostatic interaction. The in vitro release profiles of the binary-drug loaded nanoparticles revealed that both PTX and DOX were sustainably released from the particles but behaved differently. The release of DOX was pH dependent, ensuring more drug to be released in the tumor cells than in the normal ones. Hence these particles were featured by a sequential controlled drug delivery behavior with a significant cytotoxicity to cervical cancer (Hela cell) and breast cancer (MDA-MB-321) cells. The CLSM observations clearly indicated that both loaded PTX and DOX aggregated in the nucleus of tumor cells to exert their anti-tumor pharmacodynamic effect on the cells. PMID:23554308

  19. General Force-Field Parametrization Scheme for Molecular Dynamics Simulations of Conjugated Materials in Solution.

    Science.gov (United States)

    Wildman, Jack; Repiščák, Peter; Paterson, Martin J; Galbraith, Ian

    2016-08-01

    We describe a general scheme to obtain force-field parameters for classical molecular dynamics simulations of conjugated polymers. We identify a computationally inexpensive methodology for calculation of accurate intermonomer dihedral potentials and partial charges. Our findings indicate that the use of a two-step methodology of geometry optimization and single-point energy calculations using DFT methods produces potentials which compare favorably to high level theory calculation. We also report the effects of varying the conjugated backbone length and alkyl side-chain lengths on the dihedral profiles and partial charge distributions and determine the existence of converged lengths above which convergence is achieved in the force-field parameter sets. We thus determine which calculations are required for accurate parametrization and the scope of a given parameter set for variations to a given molecule. We perform simulations of long oligomers of dioctylfluorene and hexylthiophene in explicit solvent and find peristence lengths and end-length distributions consistent with experimental values. PMID:27397762

  20. Electrochemical synthesis and spectroelectrochemical characterization of triazole/thiophene conjugated polymers

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: Novel electropolymerizable monomers based on triazole–thiophene units were characterized by both spectroscopic and electrochemical methods. It was found that those monomers which were enriched with additional thiophene units in their chemical structure showed red-shifted electronic transitions and lower oxidation potentials when compared with the short-chain disubstituted triazole monomer. The monomers studied were electropolymerized in organic medium giving rise to their corresponding electroactive polymers. These materials can be p-doped at potentials values which can be properly correlated with the thiophene conjugation length of the parent precursor. As a general rule, it was observed that the longer the conjugation length, the lower the HOMO level. Only the alternating bisthiophene–triazole polymer, poly-TTT, can be both p- and n-doped within the electrochemical window of the solvent employed. The doping processes are characterized by the formation of charge traps that avoid the reversible recovery of the injected charge. In addition, polaronic species formed upon electrochemical doping seem to be at the origin of the electronic transition bands observed for all the materials in the visible low-frequency to near-infrared optical range.

  1. Triterpene sapogenin-polyarginine conjugates exhibit promising antibacterial activity against Gram-positive strains.

    Science.gov (United States)

    Na, Heiya; Li, Xiangpeng; Zou, Cunbin; Wang, Chenhong; Wang, Chao; Liu, Keliang

    2016-07-01

    Triterpene sapogenins are a group of biologically active compounds with antibacterial activity. However, the limited solubility and poor bioavailability of triterpene sapogenins restrict their therapeutic application. Polyarginine peptides are small cationic peptides with high affinities for multiple negatively charged cell membranes and possess moderate antibacterial activities. In this study, we designed and synthesized a series of sapogenin-polyarginine conjugates in which the triterpene sapogenin moiety was covalently appended to the positively charged polyarginine via click chemistry. A clear synergistic effect was found, and the conjugates exhibited potent and selective antibacterial activity against Gram-positive strains. Among them, BAc-R3 was the most promising compound, which was also proven to be nontoxic toward mammalian cells as well as stable in plasma. The mechanism of BAc-R3 primarily involves an interaction with the bacterial membrane, similar to that of antimicrobial peptides (AMPs). This scaffold design opens an avenue for the further development of novel antibiotics comprised of the combination of a peptide and a natural product. PMID:27209170

  2. Vast Hole- and Electron-Polaron Spatial Extent in Oligomeric π-Conjugated Porphyrin Arrays

    Science.gov (United States)

    Angiolillo, Paul; Rawson, Jeff; Therien, Michael

    meso-Ethyne bridged π-conjugated zinc porphyrin oligomers (PZnn compounds) have been demonstrated to evince lowest excited singlet states that are globally delocalized. It has also previously been shown that hole-polaron states of these oligomers exhibit delocalization lengths that mirror the molecular spatial dimension, 7.5 nm in the case of the heptamer. Here we demonstrate that the electron-polaron states in PZnn compounds also feature vast areal delocalization. This finding is evidenced by concurrent optical and electron spin resonance measurements, coupled with electronic structure calculations that suggest atypically small reorganization energies for one-electron reduction of these materials. These results are buttressed by electron spin relaxation measurements of PZnn electron polarons that show that both T1 and T2 relaxation times are unusually large, on the order of 103 ns and 102 ns, respectively. Since rapid charge delocalization defines an important mechanism that mitigates Coulombic stabilization of photogenerated electron-hole pairs to create separated free charge carriers, and spin polarization lifetimes feature prominently in spin currents, these findings identify conjugated materials with exceptional optical, electronic, and spintronic properties.

  3. Peptide Conjugates as Useful Molecular Tools

    OpenAIRE

    Ślósarczyk, Adam T.

    2011-01-01

    The conjugation of a small organic molecule to synthetic polypeptides from a designed set has been shown to give rise to binders with high affinity and selectivity for the phosphorylated model proteins α-casein and β-casein but not for ovoalbumin. The small organic molecule that was used for this purpose is comprised of two di-(2-picolyl)amine groups assembled on a dimethylphenyl scaffold, and is capable of complexing two Zn2+ ions to form chelates that bind the phosphate ion. The designed po...

  4. Inorganic Nanoparticles Conjugated with Biofunctional Molecules

    Institute of Scientific and Technical Information of China (English)

    J.H.Choy

    2007-01-01

    1 Results We have attempted to conjugate inorganic nanoparticles with biofunctional molecules.Recently we were quite successful in demonstrating that a two-dimensional inorganic compound like layered double hydroxide (LDH),and natural and synthetic clays can be used as gene or drug delivery carriers1-4.To the best of our knowledge,such inorganic vectors are completely new and different from conventionally developed ones such as viruses and cationic liposomes,those which are limited in certain cases of ap...

  5. Rhenium 188 labelling of peptide conjugates

    Energy Technology Data Exchange (ETDEWEB)

    Melendez-Alafort, Laura

    2001-07-01

    Many human tumours express high levels, of somatostatin receptors. In order to make possible a radiotherapeutic treatment of this kind for tumour a series of somatostatin analogues that can tightly chelate beta emitting isotopes have been developed in recent years. The work carried out for this thesis has been aimed towards development of a new therapeutic radiopharmaceutical for treatment of somatostatin receptor positive tumours. The first chapters describe work with technetium-99m to establish the labelling and analytical conditions for a somatostatin analogue, [Tyr{sup 3}]-octreotide (TOC), as a precursor to undertaking labelling studies with the beta emitter rhenium-188. 6-Hydrazinopyridine-3-carboxylic acid (HYNIC) was conjugated to TOC and labelled with {sup 99m} using different coligands. Then the stability, receptor binding and biodistribution of each complex were assessed. {sup 99m}Tc-HYNIC-TOC using EDDA as coligand showed the best characteristics, and was superior for tumour imaging in humans than the commercially available {sup 111}In-DTPA-octreotide. The conditions for labelling the HYNIC-TOC conjugate with {sup 188}Re were then optimised using tricine as a co-ligand. A labelling yield of {approx}80% was achieved. After purification however, the stability of the complex was low. The use of other coligand systems which had proved useful for {sup 99m}Tc labelling was explored, but yields were very poor. Other chelators such as diethylenetriamine pentaacetic acid (DTPA), dimercaptosuccinic acid (DMSA) and mercaptoacetyltriglycine (MAG{sub 3}) were studied as potential co-ligand agents to label the HYNIC-TOC conjugate with {sup 188}Re but, again low yields of the labelled peptide complexes were achieved. A novel {sup 188}Re-HYNIC complex was prepared in high yields using N-N-disubstituted dithiocarbamates as coligands. However to date, the specific activities achieved with this system are relatively low. The use of the [{sup 99m}Tc(CO){sub 3}(H{sub 2}O

  6. HPMA copolymer conjugates for dual therapy

    Czech Academy of Sciences Publication Activity Database

    Etrych, Tomáš; Krakovičová, Hana; Šírová, Milada; Říhová, Blanka; Ulbrich, Karel

    2008-01-01

    Roč. 132, č. 3 (2008), s. 63-65. ISSN 0168-3659. [European Symposium on Controlled Drug Delivery /10./. Noordwijk an Zee, 02.04.2008-04.04.2008] R&D Projects: GA MŠk 1M0505; GA AV ČR IAA400500806 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50200510 Keywords : dual therapy * polymer conjugates * controlled release Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.690, year: 2008

  7. Conjugation properties of tensor product multiplicities

    CERN Document Server

    Coquereaux, Robert

    2014-01-01

    It was recently proven that the total multiplicity in the decomposition into irreducibles of the tensor product lambda x mu of two irreducible representations of a simple Lie algebra is invariant under conjugation of one of them; at a given level, this also applies to the fusion multiplicities of affine algebras. Here, we show that, in the case of SU(3), the lists of multiplicities, in the tensor products lambda x mu and lambda x bar{mu}, are identical up to permutations. This latter property does not hold in general for other Lie algebras.

  8. Synthesis of gold and silver nanoparticle S-ovalbumin protein conjugates by in situ conjugation process

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Deepti, E-mail: deeptimishrajoshi@gmail.com; Soni, R. K. [Indian Institute of Technology Delhi, Physics Department (India)

    2015-05-15

    Pure gold and silver nanoparticle (NP) generation and their conjugation with protein S-ovalbumin using in situ conjugation process have been reported. The in situ conjugation involves nanosecond pulse laser ablation of pure metal target in the protein S-ovalbumin solution. Transmission electron microscopy (TEM) and UV–Visible absorption results show decrease in mean NP size along with narrow particle size distribution on ablation in S-ovalbumin solution as compared to ablation in water for both Au and Ag NPs. Also, the NP size reduction was found to be dependent on the concentration of S-ovalbumin. For AuNPs, spherical NPs of mean size 4 nm with particle size distribution 2–6 nm were obtained at 300 nM S-ovalbumin concentration. Further, it has been observed that the resultant in situ-conjugated colloid gold and silver NP solutions were quite stable even in the presence of NaCl at physiological salt concentration (0.15 M). On post-laser irradiation (532 nm, 15 mJ) for 20 min, 9 nm red shift in surface plasmon resonance peak (SPR), along with increased broadening towards longer wavelength, was observed in the AuNPs–S-ovalbumin sample. Further increase in the time of irradiation showed shift in AuNPs–S-ovalbumin SPR towards lower wavelength. On laser irradiation (532 nm, 15 mJ) for 20 min, no significant change was observed in the line shape of the plasmon absorption band of the AgNPs–S-ovalbumin conjugate. FTIR spectra revealed that S-ovalbumin peptide backbone and secondary structure remain unchanged on laser irradiation during in situ conjugation process. Thus, integrity of S-ovalbumin does not get affected, and no degradation of S-ovalbumin takes place on laser-induced in situ conjugation. Raman results confirm that both Au and Ag NPs interact with S-ovalbumin via thiol-bearing cysteine residues of the disulfide bond.

  9. Synthesis of gold and silver nanoparticle S-ovalbumin protein conjugates by in situ conjugation process

    International Nuclear Information System (INIS)

    Pure gold and silver nanoparticle (NP) generation and their conjugation with protein S-ovalbumin using in situ conjugation process have been reported. The in situ conjugation involves nanosecond pulse laser ablation of pure metal target in the protein S-ovalbumin solution. Transmission electron microscopy (TEM) and UV–Visible absorption results show decrease in mean NP size along with narrow particle size distribution on ablation in S-ovalbumin solution as compared to ablation in water for both Au and Ag NPs. Also, the NP size reduction was found to be dependent on the concentration of S-ovalbumin. For AuNPs, spherical NPs of mean size 4 nm with particle size distribution 2–6 nm were obtained at 300 nM S-ovalbumin concentration. Further, it has been observed that the resultant in situ-conjugated colloid gold and silver NP solutions were quite stable even in the presence of NaCl at physiological salt concentration (0.15 M). On post-laser irradiation (532 nm, 15 mJ) for 20 min, 9 nm red shift in surface plasmon resonance peak (SPR), along with increased broadening towards longer wavelength, was observed in the AuNPs–S-ovalbumin sample. Further increase in the time of irradiation showed shift in AuNPs–S-ovalbumin SPR towards lower wavelength. On laser irradiation (532 nm, 15 mJ) for 20 min, no significant change was observed in the line shape of the plasmon absorption band of the AgNPs–S-ovalbumin conjugate. FTIR spectra revealed that S-ovalbumin peptide backbone and secondary structure remain unchanged on laser irradiation during in situ conjugation process. Thus, integrity of S-ovalbumin does not get affected, and no degradation of S-ovalbumin takes place on laser-induced in situ conjugation. Raman results confirm that both Au and Ag NPs interact with S-ovalbumin via thiol-bearing cysteine residues of the disulfide bond

  10. Activation of the σE-Dependent Stress Pathway by Conjugative TraR May Anticipate Conjugational Stress

    OpenAIRE

    Grace, Elicia D; Gopalkrishnan, Saumya; Girard, Mary E.; Blankschien, Matthew D.; Ross, Wilma; Gourse, Richard L.; Herman, Christophe

    2014-01-01

    Horizontal gene transfer by conjugation plays a major role in bacterial evolution, allowing the acquisition of new traits, such as virulence and resistance to antibacterial agents. With the increased antibiotic resistance in bacterial pathogens, a better understanding of how bacteria modulate conjugation under changing environments and the genetic factors involved is needed. Despite the evolutionary advantages conjugation may confer, the process can be quite stressful for the donor cell. Here...

  11. Structure-Property Relationship for Two-Photon Absorbing Multiporphyrins: Supramolecular Assembly of Highly-Conjugated Multiporphyrinic Ladders and Prisms

    Energy Technology Data Exchange (ETDEWEB)

    Easwaramoorthi, Shanmugam; Jang, So Young; Yoon, Zin Seok; Lim, Jong Min; Lee, Cheng-Wei; Mai, Chi-Lun; Liu, Yen-Chun; Yeh, Chen-Yu; Vura-Weis, Josh; Wasielewski, Michael R.; Kim, Dongho (NWU); (Yonsei); (NSHU)

    2008-10-03

    Two-photon absorption (TPA) phenomena of a series of single-strand as well as supramolecular self-assembled ladders and prisms of highly conjugated ethyne bridged multiporphyrin dimer, trimer, and star shaped pentamer have been investigated. The ligand mediated self-assembled supramolecular structures were characterized by UV-visible spectroscopy and small- and wide-angle X-ray scattering (SAXS/WAXS) analysis. The TPA cross section values of multiporphyrins increase nonlinearly from {approx}100 to {approx}18000 GM with an increased number of porphyrin units and elongated ?-conjugation length by virtue of charge transfer and excited-state cumulenic configurations. The observed opposite TPA behavior between their supramolecular ladder and prism configurations necessitates the importance of interstrand interactions between the multiporphyrinic units and the overall shape of the assembly. Furthermore, the diminished TPA cross section of the pentamer, despite the increased ?-conjugation resulting from duplex formation suggests that destabilizing the essential functional configurations at the cost of elongation of ?-delocalization pathway must cause unfavorable effects. We have also shown that one- and two-photon allowed energy-levels of linear multiporphyrins are nearly isoenergetic and the latter transition originates exclusively from the extent of ?-delocalization within the molecule. The identical TPA maximum position of the trimer and pentamer indicates that the TPA of the pentamer arises only from its basic trimer unit in spite of its extended two-dimensional {pi}-conjugation pathway involving five porphyrinic units.

  12. Cellulose nanocrystals with tunable surface charge for nanomedicine

    Science.gov (United States)

    Hosseinidoust, Zeinab; Alam, Md Nur; Sim, Goeun; Tufenkji, Nathalie; van de Ven, Theo G. M.

    2015-10-01

    Crystalline nanoparticles of cellulose exhibit attractive properties as nanoscale carriers for bioactive molecules in nanobiotechnology and nanomedicine. For applications in imaging and drug delivery, surface charge is one of the most important factors affecting the performance of nanocarriers. However, current methods of preparation offer little flexibility for controlling the surface charge of cellulose nanocrystals, leading to compromised colloidal stability under physiological conditions. We report a synthesis method that results in nanocrystals with remarkably high carboxyl content (6.6 mmol g-1) and offers continuous control over surface charge without any adjustment to the reaction conditions. Six fractions of nanocrystals with various surface carboxyl contents were synthesized from a single sample of softwood pulp with carboxyl contents varying from 6.6 to 1.7 mmol g-1 and were fully characterized. The proposed method resulted in highly stable colloidal nanocrystals that did not aggregate when exposed to high salt concentrations or serum-containing media. Interactions of these fractions with four different tissue cell lines were investigated over a wide range of concentrations (50-300 μg mL-1). Darkfield hyperspectral imaging and confocal microscopy confirmed the uptake of nanocrystals by selected cell lines without any evidence of membrane damage or change in cell density; however a charge-dependent decrease in mitochondrial activity was observed for charge contents higher than 3.9 mmol g-1. A high surface carboxyl content allowed for facile conjugation of fluorophores to the nanocrystals without compromising colloidal stability. The cellular uptake of fluoresceinamine-conjugated nanocrystals exhibited a time-dose dependent relationship and increased significantly with doubling of the surface charge.Crystalline nanoparticles of cellulose exhibit attractive properties as nanoscale carriers for bioactive molecules in nanobiotechnology and nanomedicine. For

  13. Antibody-Conjugated Nanoparticles for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Manuel Arruebo

    2009-01-01

    Full Text Available Nanoscience and Nanotechnology have found their way into the fields of Biotechnology and Medicine. Nanoparticles by themselves offer specific physicochemical properties that they do not exhibit in bulk form, where materials show constant physical properties regardless of size. Antibodies are nanosize biological products that are part of the specific immune system. In addition to their own properties as pathogens or toxin neutralizers, as well as in the recruitment of immune elements (complement, improving phagocytosis, cytotoxicity antibody dependent by natural killer cells, etc., they could carry several elements (toxins, drugs, fluorochroms, or even nanoparticles, etc. and be used in several diagnostic procedures, or even in therapy to destroy a specific target. The conjugation of antibodies to nanoparticles can generate a product that combines the properties of both. For example, they can combine the small size of nanoparticles and their special thermal, imaging, drug carrier, or magnetic characteristics with the abilities of antibodies, such as specific and selective recognition. The hybrid product will show versatility and specificity. In this review, we analyse both antibodies and nanoparticles, focusing especially on the recent developments for antibody-conjugated nanoparticles, offering the researcher an overview of the different applications and possibilities of these hybrid carriers.

  14. The coordination dynamics of mobile conjugate reinforcement.

    Science.gov (United States)

    Kelso, J A Scott; Fuchs, Armin

    2016-02-01

    What we know about infant learning and memory is founded largely on systematic studies by the late Carolyn Rovee-Collier (1942-2014) and her associates of a phenomenon called mobile conjugate reinforcement. Experiments show that when a ribbon is attached from a 3-month-old infant's foot to a mobile suspended overhead the baby quickly realizes it can make the mobile move. The mobile, which offers interesting sights and sounds, responds conjugately to the baby's vigorous kicks which increase in rate by a factor of 3-4. In this paper, using the concepts, methods and tools of coordination dynamics, we present a theoretical model which reproduces the experimental observations of Rovee-Collier and others and predicts a number of additional features that can be experimentally tested. The model is a dynamical system consisting of three equations, one for the baby's leg movements, one for the jiggling motion of the mobile and one for the functional coupling between the two. A key mechanism in the model is positive feedback which is shown to depend sensitively on bifurcation parameters related to the infant's level of attention and inertial properties of the mobile. The implications of our model for the dynamical (and developmental) origins of agency are discussed. PMID:26759265

  15. π-Clamp-mediated cysteine conjugation

    Science.gov (United States)

    Zhang, Chi; Welborn, Matthew; Zhu, Tianyu; Yang, Nicole J.; Santos, Michael S.; van Voorhis, Troy; Pentelute, Bradley L.

    2016-02-01

    Site-selective functionalization of complex molecules is one of the most significant challenges in chemistry. Typically, protecting groups or catalysts must be used to enable the selective modification of one site among many that are similarly reactive, and general strategies that selectively tune the local chemical environment around a target site are rare. Here, we show a four-amino-acid sequence (Phe-Cys-Pro-Phe), which we call the ‘π-clamp’, that tunes the reactivity of its cysteine thiol for site-selective conjugation with perfluoroaromatic reagents. We use the π-clamp to selectively modify one cysteine site in proteins containing multiple endogenous cysteine residues. These examples include antibodies and cysteine-based enzymes that would be difficult to modify selectively using standard cysteine-based methods. Antibodies modified using the π-clamp retained binding affinity to their targets, enabling the synthesis of site-specific antibody-drug conjugates for selective killing of HER2-positive breast cancer cells. The π-clamp is an unexpected approach to mediate site-selective chemistry and provides new avenues to modify biomolecules for research and therapeutics.

  16. The multigrid preconditioned conjugate gradient method

    Science.gov (United States)

    Tatebe, Osamu

    1993-01-01

    A multigrid preconditioned conjugate gradient method (MGCG method), which uses the multigrid method as a preconditioner of the PCG method, is proposed. The multigrid method has inherent high parallelism and improves convergence of long wavelength components, which is important in iterative methods. By using this method as a preconditioner of the PCG method, an efficient method with high parallelism and fast convergence is obtained. First, it is considered a necessary condition of the multigrid preconditioner in order to satisfy requirements of a preconditioner of the PCG method. Next numerical experiments show a behavior of the MGCG method and that the MGCG method is superior to both the ICCG method and the multigrid method in point of fast convergence and high parallelism. This fast convergence is understood in terms of the eigenvalue analysis of the preconditioned matrix. From this observation of the multigrid preconditioner, it is realized that the MGCG method converges in very few iterations and the multigrid preconditioner is a desirable preconditioner of the conjugate gradient method.

  17. Modelling airport congestion charges

    OpenAIRE

    Janić, Milan

    2012-01-01

    This article deals with modelling congestion charges at an airport. In this context, congestion charging represents internalizing the cost of marginal delays that a flight imposes on other flights due to congestion. The modelling includes estimating congestion and flight delays, the cost of these delays and the efficiency of particular flights following the introduction ofa congestion charge. The models are applied to an airport / New York LaGuardia / to illustrate their ability to handle mor...

  18. The Role of the Conjugate Bridge in Electronic Structures and Related Properties of Tetrahydroquinoline for Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    You-Zhi Wu

    2013-03-01

    Full Text Available To understand the role of the conjugate bridge in modifying the properties of organic dye sensitizers in solar cells, the computations of the geometries and electronic structures for 10 kinds of tetrahydroquinoline dyes were performed using density functional theory (DFT, and the electronic absorption and fluorescence properties were investigated via time dependent DFT. The population analysis, molecular orbital energies, radiative lifetimes, exciton binding energies (EBE, and light harvesting efficiencies (LHE, as well as the free energy changes of electron injection ( and dye regeneration ( were also addressed. The correlation of charge populations and experimental open-circuit voltage (Voc indicates that more charges populated in acceptor groups correspond to larger Voc. The elongating of conjugate bridge by thiophene units generates the larger oscillator strength, higher LHE, larger absolute value of , and longer relative radiative lifetime, but it induces the decreasing of EBE and . So the extending of conjugate bridge with thiopene units in organic dye is an effective way to increase the harvest of solar light, and it is also favorable for electron injection due to their larger . While the inversely correlated relationship between EBE and LHE implies that the dyes with lower EBE produce more efficient light harvesting.

  19. Conjugated assembly of colloidal zinc oxide quantum dots and multiwalled carbon nanotubes for an excellent photosensitive ultraviolet photodetector.

    Science.gov (United States)

    Boruah, Buddha Deka; Misra, Abha

    2016-09-01

    Conjugation of highly dense colloidal zinc oxide quantum dots (ZnO QDs) on multiwalled carbon nanotubes (ZnO QDs@MWCNTs) is achieved for high performance ultraviolet (UV) photodetection. Significant improvement in the photoresponse of the ZnO QDs@MWCNTs photodetector (PD) is established as compared to a pristine ZnO QDs PD. The conjugation of two constituents allows the direct transfer of photoinduced charge carriers in ZnO QDs to MWCNTs for an efficient electrical path that considerably reduces charge recombination during UV exposure. Linearity in the response current with both the UV illumination intensity as well as external bias voltage reveals the photoelastic behavior of the ZnO QDs@MWCNTs PD. Moreover, the PD displays faster response and recovery times of 1.6 s and 1.9 s, respectively, than the most conventional PDs. In addition, spectral photoresponse analysis of the PD presents visible-blind behavior. Overall, conjugation of the hybrid heterostructure presented excellent photoelastic, high performance and visible-blind UV photodetection. PMID:27454746

  20. Solvent-dependent self-assembly and ordering in slow-drying semi-crystalline conjugated polymer solutions

    KAUST Repository

    Zhao, Kui

    2015-09-07

    The mechanistic understanding of the intrinsic molecular self-assembly of conjugated polymers is of immense importance to controlling the microstructure development in organic semiconducting thin films, with meaningful impact on charge transport and optoelectronic properties. Yet, to date the vast majority of studies have focused on the fast solution process itself, with studies of slower intrinsic molecular self-assembly in formulations lagging behind. Here we have investigated molecular self-assembly during spontaneous organization and uncovered how changes in formulation influence the microstructure, morphology and transport properties of conjugated polymer thin films. Our results suggest that the polymer-solvent interaction is the key factor for the molecular self-assembly and changes in macroscopic charge transport, which is in contrast with most solution processes, such as spin-coating and blade coating, where solvent drying kinetics dominates the aggregation and crystallization processes. Energetically favourable interactions between the polymer and its solvent are shown to cause chain expansion, resulting in a large hydrodynamic volume and few chain entanglements in solution. This provides molecular freedom for self-assembly and is shown to greatly enhance the local and long range order of the polymer, intra-chain backbone planarity and crystallite size. These improvements, in turn, are shown to endow the conjugated polymer with high carrier transport, as demonstrated by organic thin film transistors.

  1. `Majorana Mass' Fermions as Untrue Majorana Particles, Rather Endowed with Pseudoscalar-Type Charges than Genuinely Neutral

    Science.gov (United States)

    Ziino, G.

    2016-03-01

    The idea of a `Majorana mass' to make a chiral neutrino really neutral is here reconsidered. It is pointed out that such an approach, unlike Majorana's (non-chiral) old one, does not strictly lead, in general, to a true self-conjugate particle. This can be seen on directly using the basic definition (or fundamental representation) of charge conjugation C in Quantum Field Theory, as an operation just acting on annihilation and creation operators and just expressing particle-antiparticle interchange. It is found, indeed, that the `active' and `sterile' whole fields which can be obtained from mixing the chiral components of two mutually charge-conjugate Dirac fields are themselves `charge conjugate' to each other (rather than individually self-conjugate). These fields, taken as mass eigenfields (as in the `Majorana mass' case), are shown to describe particles carrying pseudoscalar-type charges and being neutral relative to scalar-type charges only. For them, ` CP symmetry' would be nothing but pure mirror symmetry, and C violation (already implied in their respective `active' and `sterile' behaviors) should then involve time-reversal violation as well. The new (no longer strictly chargeless) `Majorana mass' neutrino model still proves, however, neither to affect the usual expectation for a neutrinoless double β-decay, nor to prevent `active' and `sterile' neutrino varieties from generally taking different mass values. One has, on the other hand, that any fermion being just a genuine (i.e. really self-conjugate) Majorana particle cannot truly exist in two distinct—`active' and `sterile'—versions, and it can further bear only a unified mass kind which may at once be said to be either a `Majorana-like' or a `Dirac-like' mass kind.

  2. Charge Injection and Transport in Metal/Polymer Chains/Metal Sandwich Structure

    Institute of Scientific and Technical Information of China (English)

    LI Hai-Hong; LI Dong-Mei; LI Yuan; GAO Kun; LIU De-Sheng; XIE Shi-Jie

    2008-01-01

    @@ Using the tight-binding Su-Schrieffer-Heeger model and a nonadiabatic dynamic evolution method, we study the dynamic processes of the charge injection and transport in a metal/two coupled conjugated polymer chains/metal structure. It is found that the charge interchain transport is determined by the strength of the electric field and the magnitude of the voltage bias applied on the metal electrode. The stronger electric field and the larger voltage bias are both in favour of the charge interchain transport.

  3. Charge extraction from nanostructured hybrid organic-inorganic photovoltaic cells

    Science.gov (United States)

    Goh, Chiatzun

    Conjugated polymers are attractive for use in photovoltaic (PV) cells because they are highly absorptive, their absorption spectrum can be tuned to match various regions of the solar spectrum and their solubility in common solvents enables the use of low-cost printing technique to mass produce PV panels. Photoexcitation of conjugated polymers forms excitons, which are bound electron-hole pairs. In order to convert these excitons into free carriers, the polymers have to be blended with an electron acceptor in close promixity of ˜10 nm. The charge transfer process at the donor-acceptor interface provides the necessary driving force to split excitons, while the close proximity guarantees excitons reaching an interface before decaying. Once the carriers are split, they have to be transported to their respective electrodes before recombining. Ordered nanostructured titania (TiO2) matrix infiltrated with conjugated polymers is a promising acceptor-donor system, which can potentially meet these requirements. In this work, several optimizations are shown to be essential for increasing the performance of TiO2/polymer cells. First, we measure the hole mobility of poly(3-hexylthiophene) (P3HT) in a thin film diode in the space-charge limited regime. We show that the mobility increases with the polymer molecular weight and can be correlated to the film morphology. The anisotropy in P3HT chain packing suggests that its diode mobility of 10-4 cm 2/Vs can be further enhanced upon chain alignment in straight nanopores. Second, we investigate the use of molecular surface modification to control the interfacial energetics and charge transfer dynamics. By introducing dipoles at the TiO2/P3HT interface, the interfacial energy offset can be changed resulting in a concomitant change in the open circuit voltage. In addition, certain modifiers improve exciton harvesting by mediating charge transfer from the polymer to TiO2. We further show that the use of an amphiphilic molecule

  4. Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers

    International Nuclear Information System (INIS)

    According to the one-dimensional tight-binding Su—Schrieffer—Heeger model, we have investigated the effects of charged polarons on the static polarizability, αxx, and the second order hyperpolarizabilities, γxxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su-Schrieffer-Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron-electron interactions on αxx and γxxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of αxx and γxxxx increase as the on-site Coulomb interaction U increases for U c and decrease with U for U > Uc, where Uc is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of αmax or γmax. It is found that the effect of the e-e interaction on the value of αxx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γxxxx is sensitive both to the ratio of U to V and to the size of the molecule. (rapid communication)

  5. Enhanced Antioxidant Activities of Metal Conjugates of Curcumin Derivatives

    OpenAIRE

    Dutta, Sabari; Murugkar, Anupa; Gandhe, Nitasha; Padhye, Subhash

    2001-01-01

    Antioxidant properties of three Curcumin derivatives in which the 1,3-diketone system is appended with nitrogen and sulfur donors and their copper conjugates are examined for the first time. Metal conjugation seems to offer distinct advantages in radical scavenging activities of curcumin compounds.

  6. An updated view of plasmid conjugation and mobilization in Staphylococcus.

    Science.gov (United States)

    Ramsay, Joshua P; Kwong, Stephen M; Murphy, Riley J T; Yui Eto, Karina; Price, Karina J; Nguyen, Quang T; O'Brien, Frances G; Grubb, Warren B; Coombs, Geoffrey W; Firth, Neville

    2016-01-01

    The horizontal gene transfer facilitated by mobile genetic elements impacts almost all areas of bacterial evolution, including the accretion and dissemination of antimicrobial-resistance genes in the human and animal pathogen Staphylococcus aureus. Genome surveys of staphylococcal plasmids have revealed an unexpected paucity of conjugation and mobilization loci, perhaps suggesting that conjugation plays only a minor role in the evolution of this genus. In this letter we present the DNA sequences of historically documented staphylococcal conjugative plasmids and highlight that at least 3 distinct and widely distributed families of conjugative plasmids currently contribute to the dissemination of antimicrobial resistance in Staphylococcus. We also review the recently documented "relaxase-in trans" mechanism of conjugative mobilization facilitated by conjugative plasmids pWBG749 and pSK41, and discuss how this may facilitate the horizontal transmission of around 90% of plasmids that were previously considered non-mobilizable. Finally, we enumerate unique sequenced S. aureus plasmids with a potential mechanism of mobilization and predict that at least 80% of all non-conjugative S. aureus plasmids are mobilizable by at least one mechanism. We suggest that a greater research focus on the molecular biology of conjugation is essential if we are to recognize gene-transfer mechanisms from our increasingly in silico analyses. PMID:27583185

  7. A NONMONOTONE CONJUGATE GRADIENT ALGORITHM FOR UNCONSTRAINED OPTIMIZATION

    Institute of Scientific and Technical Information of China (English)

    DAI Yuhong

    2002-01-01

    Conjugate gradient methods are very important methods for unconstrained optimization, especially for large scale problems. In this paper, we propose a new conjugate gradient method, in which the technique of nonmonotone line search is used. Under mild assumptions, we prove the global convergence of the method. Some numerical results are also presented.

  8. Enzyme linked immunoassay with stabilized polymer saccharide enzyme conjugates

    Science.gov (United States)

    Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

    1997-11-25

    An improvement in enzyme linked immunoassays is disclosed wherein the enzyme is in the form of a water soluble polymer saccharide conjugate which is stable in hostile environments. The conjugate comprises the enzyme which is linked to the polymer at multiple points through saccharide linker groups. 19 figs.

  9. Method for synthesizing peptides with saccharide linked enzyme polymer conjugates

    Science.gov (United States)

    Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

    1997-06-17

    A method is disclosed for synthesizing peptides using water soluble enzyme polymer conjugates. The method comprises catalyzing the peptide synthesis with enzyme which has been covalently bonded to a polymer through at least three linkers which linkers have three or more hydroxyl groups. The enzyme is conjugated at lysines or arginines. 19 figs.

  10. An Improved Synthesis of Arsenic-Biotin Conjugates

    OpenAIRE

    Heredia-Moya, Jorge; KIRK, KENNETH L.

    2008-01-01

    An amide linked conjugate of p-aminophenylarsine oxide and biotin is conveniently prepared in a one-pot procedure by reaction of biotinyl chloride, formed in situ, with p-aminophenyldichloroarsine. Reaction of the arsine oxide-biotin conjugate with 1,2-ethanedithiol produces the stabilized dithiarsolane. These reagents are now readily available for a variety of applications.

  11. Overview on the Phase Conjugation Techniques of the Retrodirective Array

    OpenAIRE

    Tian Ling Zhang; Xiao Wei Shi; Yu Chun Guo; Lei Chen

    2010-01-01

    This paper presents an overview on the phase conjugation techniques of the retrodirective antenna array. The concepts, advantages, and disadvantages of phase conjugation techniques are introduced. The self-phasing characteristic and technical difficulties of the array are presented as well as their structures and applications. Further researches in this area are presented finally.

  12. Bone marrow purging by a xanthine oxidase-antibody conjugate.

    Science.gov (United States)

    Dinota, A; Tazzari, P L; Abbondanza, A; Battelli, M G; Gobbi, M; Stirpe, F

    1990-07-01

    The selective cytotoxicity of the xanthine oxidase conjugated to an 8A monoclonal antibody recognizing a human plasma cell-associated antigen has been described. The selectivity and the toxicity of the hypoxanthine/conjugated xanthine oxidase system was increased by removing the excess of conjugate and by adding chelated iron. Under these experimental conditions the cytotoxicity of the conjugate exceeded that of free xanthine oxidase by one order of magnitude. The conjugate effectively purged bone marrow from infiltrating neoplastic plasma cells and added target Raji cells, provided blood was removed and bone marrow peroxidases were exhausted. In conditions of purging effectiveness the conjugate had no toxicity to CFU-GM. No toxicity to mice was observed after i.v. injection of xanthine oxidase-antibody conjugate up to 2.9 U/kg body weight. Thus the hypoxanthine/conjugated xanthine oxidase system could be an effective and nontoxic tool for the ex vivo bone marrow purging in multiple myeloma patients for autologous transplantation. PMID:2390631

  13. Link optimization for DWDM transmission with an optical phase conjugation.

    Science.gov (United States)

    Rosa, Paweł; Rizzelli, Giuseppe; Ania-Castañón, Juan Diego

    2016-07-25

    We characterize in-span signal power asymmetry in random distributed feedback ultralong Raman laser-amplified WDM transmission and numerically optimize fiber span length and operating band to achieve the lowest inter-span signal power asymmetry between transmitted and optically conjugated channels in systems relying upon mid-link optical conjugation to combat fiber nonlinear impairments. PMID:27464097

  14. Prostaglandin phospholipid conjugates with unusual biophysical and cytotoxic properties

    DEFF Research Database (Denmark)

    Pedersen, Palle Jacob; Adolph, Sidsel K.; Andresen, Thomas Lars;

    2010-01-01

    The synthesis of two secretory phospholipase A(2) IIA sensitive 15-deoxy-Delta(12,14)-prostaglandin J(2) phospholipid conjugates is described and their biophysical and biological properties are reported. The conjugates spontaneously form particles in the liposome size region upon dispersion in an...

  15. Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers.

    Science.gov (United States)

    Xu, Lai; Li, Youyong

    2016-01-01

    The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers. PMID:27356483

  16. Genetic Drift Suppresses Bacterial Conjugation in Spatially Structured Populations

    Science.gov (United States)

    Freese, Peter D.; Korolev, Kirill S.; Jiménez, José I.; Chen, Irene A.

    2014-02-01

    Conjugation is the primary mechanism of horizontal gene transfer that spreads antibiotic resistance among bacteria. Although conjugation normally occurs in surface-associated growth (e.g., biofilms), it has been traditionally studied in well-mixed liquid cultures lacking spatial structure, which is known to affect many evolutionary and ecological processes. Here we visualize spatial patterns of gene transfer mediated by F plasmid conjugation in a colony of Escherichia coli growing on solid agar, and we develop a quantitative understanding by spatial extension of traditional mass-action models. We found that spatial structure suppresses conjugation in surface-associated growth because strong genetic drift leads to spatial isolation of donor and recipient cells, restricting conjugation to rare boundaries between donor and recipient strains. These results suggest that ecological strategies, such as enforcement of spatial structure and enhancement of genetic drift, could complement molecular strategies in slowing the spread of antibiotic resistance genes.

  17. Tanzawaic Acids, a Chemically Novel Set of Bacterial Conjugation Inhibitors

    Science.gov (United States)

    Getino, María; Fernández-López, Raúl; Palencia-Gándara, Carolina; Campos-Gómez, Javier; Sánchez-López, Jose M.; Martínez, Marta; Fernández, Antonio; de la Cruz, Fernando

    2016-01-01

    Bacterial conjugation is the main mechanism for the dissemination of multiple antibiotic resistance in human pathogens. This dissemination could be controlled by molecules that interfere with the conjugation process. A search for conjugation inhibitors among a collection of 1,632 natural compounds, identified tanzawaic acids A and B as best hits. They specially inhibited IncW and IncFII conjugative systems, including plasmids mobilized by them. Plasmids belonging to IncFI, IncI, IncL/M, IncX and IncH incompatibility groups were targeted to a lesser extent, whereas IncN and IncP plasmids were unaffected. Tanzawaic acids showed reduced toxicity in bacterial, fungal or human cells, when compared to synthetic conjugation inhibitors, opening the possibility of their deployment in complex environments, including natural settings relevant for antibiotic resistance dissemination. PMID:26812051

  18. Charge transfer states appear in the π-conjugated pure hydrocarbon molecule on Cu(111)

    Science.gov (United States)

    Yonezawa, Keiichirou; Suda, Yosuke; Yanagisawa, Susumu; Hosokai, Takuya; Kato, Kengo; Yamaguchi, Takuma; Yoshida, Hiroyuki; Ueno, Nobuo; Kera, Satoshi

    2016-04-01

    We report on the results of experimental and theoretical studies on the electronic structure of gas-phase diindenoperylene (DIP) and DIP-monolayer (ML) on Cu(111). Vapor-phase ultraviolet photoelectron spectroscopy (UPS) was realized for 11.3 mg of DIP, giving reference orbital energies of isolated DIP, and UPS and inverse photoemission spectroscopy of DIP-ML/graphite were performed to obtain DIP-ML electronic states at a weak interfacial interaction. Furthermore, first-principles calculation clearly demonstrates the interfacial rearrangement. These results provide evidence that the rearrangement of orbital energies, which is realized in HOMO-LUMO and HOMO-HOMO-1 gaps, brings partially occupied LUMO through the surface-induced aromatic stabilization of DIP, a pure hydrocarbon molecule, on Cu(111).

  19. On the non-relativistic limit of charge conjugation in QED

    OpenAIRE

    Perez, B. Carballo; Socolovsky, M.

    2010-01-01

    Even if at the level of the non-relativistic limit of full QED, C is not a symmetry, the limit of this operation does exist for the particular case when the electromagnetic field is considered a classical external object coupled to the Dirac field. This result extends the one obtained when fermions are described by the Schroedinger-Pauli equation. We give the expressions for both the C matrix and the $\\hat{C}$ operator for galilean electrons and positrons interacting with the external electro...

  20. On the non-relativistic limit of charge conjugation in QED

    Science.gov (United States)

    Carballo Pérez, B.; Socolovsky, M.

    2011-01-01

    Even if at the level of the non-relativistic limit of full QED, C is not a symmetry, the limit of this operation does exist for the particular case when the electromagnetic field is considered a classical external object coupled to the Dirac field. This result extends the one obtained when fermions are described by the Schrödinger-Pauli equation. We give the expressions for both the C matrix and the hat{{C}} operator for Galilean electrons and positrons interacting with the external electromagnetic field. The result is relevant in relation to recent experiments with antihydrogen.

  1. Charge Conjugation Violation in Supernovae and The Neutron Shortage for R-Process Nucelosynthesis

    CERN Document Server

    Horowitz, C J; Li, Gang

    2000-01-01

    Core collapse supernovae are dominated by energy transport from neutrinos. Therefore, some supernova properties could depend on symetries and features of the standard model weak interactions. The cross section for neutrino capture is larger than that for antineutrino capture by one term of order the neutrino energy over the nucleon mass. This reduces the ratio of neutrons to protons in the $\

  2. ä-conjugated polymers. Photoinduced electron transfer, ion switching, and charge carrier generation and transport

    Czech Academy of Sciences Publication Activity Database

    Nešpůrek, Stanislav

    Goa: Chemical Physics Group, Tata Institute of Fundamental Research , Homi Bhabha Road, Bombay, 1994. s. 58. [International Conference on Molecular Electronics and Biocomputing. 25.09.1994-30.09.1994, Goa] R&D Projects: GA AV ČR IAA450105

  3. Higher charge periodic monopoles

    OpenAIRE

    Maldonado, Rafael

    2013-01-01

    We consider singly periodic solutions to the SU(2) Bogomolny equations and use the Nahm transform to generate a class of monopoles of charge k>2, thereby extending known results for lower charge chains. Some simple scattering processes are presented and a comparison made with geodesic motion of monopoles in $\\mathbb{R}^3$.

  4. Charged weak currents

    International Nuclear Information System (INIS)

    In this review of charged weak currents we shall concentrate on inclusive high energy neutrino physics. The plan of this review is the following: general structure of charged current; new results on total cross-section; Callan-Gross relation; antiquark distribution; scaling violations and tests of QCD. At the end we will give a very short summary on multilepton physics

  5. Electric Charge as a Form of Imaginary Energy

    Directory of Open Access Journals (Sweden)

    Tianxi Zhang

    2008-04-01

    Full Text Available Electric charge is considered as a form of imaginary energy. With this consideration, the energy of an electrically charged particle is a complex number. The real part is proportional to the mass, while the imaginary part is proportional to the electric charge. The energy of an antiparticle is given by conjugating the energy of its corresponding particle. Newton's law of gravity and Coulomb's law of electric force are classically unified into a single expression of the interaction between the complex energies of two electrically charged particles. Interaction between real energies (or masses is the gravitational force. Interaction between imaginary energies (or electric charges is the electromagnetic force. Since radiation is also a form of real energy, there are another two types of interactions between real energies: the mass-radiation interaction and the radiation-radiation interaction. Calculating the work done by the mass-radiation interaction on a photon, we can derive the Einsteinian gravitational redshift. Calculating the work done by the radiation-radiation interaction on a photon, we can obtain a radiation redshift. This study suggests the electric charge as a form of imaginary energy, so that classically unifies the gravitational and electric forces and derives the Einsteinian gravitational redshift.

  6. DNA hybridization activity of single-stranded DNA-conjugated gold nanoparticles used as probes for DNA detection

    Science.gov (United States)

    Kira, Atsushi; Matsuo, Kosuke; Nakajima, Shin-ichiro

    2016-02-01

    Colloidal nanoparticles (NPs) have potential applications in bio-sensing technologies as labels or signal enhancers. In order to meet demands for a development of biomolecular assays by a quantitative understanding of single-molecule, it is necessary to regulate accuracy of the NPs probes modified with biomolecules to optimize the characteristics of NPs. However, to our knowledge, there is little information about the structural effect of conjugated biomolecules to the NPs. In this study, we investigated the contribution of a density of single-stranded DNA (ssDNA) conjugating gold NP to hybridization activity. Hybridization activity decreased in accordance with increases in the density of attached ssDNAs, likely due to electrostatic repulsion generated by negatively charged phosphate groups in the ssDNA backbone. These results highlight the importance of controlling the density of ssDNAs attached to the surface of NPs used as DNA detection probes.

  7. Human glutathione S-transferase-mediated glutathione conjugation of curcumin and efflux of these conjugates in caco-2 cells

    NARCIS (Netherlands)

    Usta, M.; Wortelboer, H.M.; Vervoort, J.; Boersma, M.G.; Rietjens, I.M.C.M.; Bladeren, P.J. van; Cnubben, N.H.P.

    2007-01-01

    Curcumin, an α,β-unsaturated carbonyl compound, reacts with glutathione, leading to the formation of two monoglutathionyl curcumin conjugates. In the present study, the structures of both glutathione conjugates of curcumin were identified by LC-MS and one- and two-dimensional 1H NMR analysis, and th

  8. Human glutathione S-transferase-mediated glutathione conjugation of curcumin and efflux of these conjugates in Caco-2 cells

    NARCIS (Netherlands)

    Usta, M.; Wortelboer, H.M.; Vervoort, J.J.M.; Boersma, M.G.; Rietjens, I.M.C.M.; Bladeren, van P.J.; Cnubben, N.H.P.

    2007-01-01

    Curcumin, an alpha,beta-unsaturated carbonyl compound, reacts with glutathione, leading to the formation of two monoglutathionyl curcumin conjugates. In the present study, the structures of both glutathione conjugates of curcumin were identified by LC-MS and one- and two-dimensional H-1 NMR analysis

  9. Induced Charge Capacitive Deionization

    CERN Document Server

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

    2016-01-01

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

  10. Alendronate conjugated nanoparticles for calcification targeting.

    Science.gov (United States)

    Li, Nanying; Song, Juqing; Zhu, Guanglin; Shi, Xuetao; Wang, Yingjun

    2016-06-01

    In this article, the synthesis of a novel calcification-targeting nanoparticle (NP) is reported, which is realized through dopamine self-polymerization on the poly(lactic-co-glycolic acid) (PLGA) particle surface and subsequent alendronate conjugation. Cell viability and proliferation tests confirmed that such particle has low cytotoxicity and good biocompatibility. Experiments were designed to observe whether the synthesized NPs can pass through an obstructive hydrogel and directly bind themselves to hydroxyapatite (HA) NPs (mimicking calcified spots) and HA porous scaffolds (mimicking calcified tissues); and the result was positive, indicating ingenious targeting of NPs on calcifications. The calcification-targeting NPs are expected to be with promising applications on calcification-related disease diagnoses and therapies. PMID:26970822

  11. Identification of excited states in conjugated polymers

    CERN Document Server

    Hartwell, L J

    2003-01-01

    This thesis reports quasi steady state photoinduced absorption measurements from three conjugated polymers: polypyridine (PPy), polyfluorene (PFO) and the emeraldine base (EB) form of polyaniline. The aim of these experiments was to determine the nature of the photoexcited states existing in these materials in the millisecond time domain, as this has important consequences for the operation of real devices manufactured using these materials. The results from the photoinduced absorption experiments are closely compared with published results from pulse radiolysis experiments. In all cases there is very good correspondence between the two data sets, which has enabled the photoexcited states to be assigned with a high degree of confidence. Quasi steady-state photoinduced absorption involves the measurement of the change in absorption of a material in response to optical excitation with a laser beam. The changes in absorption are small, so a instrument was developed and optimised for each different sample. Lock-i...

  12. Conjugation properties of tensor product multiplicities

    International Nuclear Information System (INIS)

    It was recently proven that the total multiplicity in the decomposition into irreducibles of the tensor product λ⊗μ of two irreducible representations of a simple Lie algebra is invariant under conjugation of one of them; at a given level, this also applies to the fusion multiplicities of affine algebras. Here, we show that, in the case of SU(3), the lists of multiplicities, in the tensor products λ⊗μ and λ⊗ μ-bar , are identical up to permutations. This latter property does not hold in general for other Lie algebras. We conjecture that the same property should hold for the fusion product of the affine algebra of SU(3) at finite levels, but this is not investigated in the present paper. (paper)

  13. Conjugated Linoleic Acid (CLA-An Overview

    Directory of Open Access Journals (Sweden)

    D J Crumb

    2011-09-01

    Full Text Available Summary: Conjugated linoleic acid (CLA is a group of octadecadienoic acids that are naturally present in the highest concentrations in foods originating in ruminant animals, and dairy products such as milk. Especially large numbers of CLA polymers have been detected in beef, lamb and milk fat. Results from many in vitro and animal studies, though conflicting, have suggested that CLA supplementation may have beneficial effect on obesity, weight management, cancer, diabetes and atherosclerosis. This article provides a brief overview on the functionality, safety and toxicity of CLA as described in literature. .   Industrial Relevance: CLA is a functional food and dietary supplement ingredient with potential benefits against a number of metabolic chronic diseases. However, the mechanism of action and its toxicological effects are not very well understood. These factors may play an important role in the effectiveness as CLA as a viable functional dietary bioactive compound.

  14. A fast, preconditioned conjugate gradient Toeplitz solver

    Science.gov (United States)

    Pan, Victor; Schrieber, Robert

    1989-01-01

    A simple factorization is given of an arbitrary hermitian, positive definite matrix in which the factors are well-conditioned, hermitian, and positive definite. In fact, given knowledge of the extreme eigenvalues of the original matrix A, an optimal improvement can be achieved, making the condition numbers of each of the two factors equal to the square root of the condition number of A. This technique is to applied to the solution of hermitian, positive definite Toeplitz systems. Large linear systems with hermitian, positive definite Toeplitz matrices arise in some signal processing applications. A stable fast algorithm is given for solving these systems that is based on the preconditioned conjugate gradient method. The algorithm exploits Toeplitz structure to reduce the cost of an iteration to O(n log n) by applying the fast Fourier Transform to compute matrix-vector products. Matrix factorization is used as a preconditioner.

  15. Conjugate natural convection between horizontal eccentric cylinders

    Science.gov (United States)

    Nasiri, Davood; Dehghan, Ali Akbar; Hadian, Mohammad Reza

    2016-06-01

    This study involved the numerical investigation of conjugate natural convection between two horizontal eccentric cylinders. Both cylinders were considered to be isothermal with only the inner cylinder having a finite wall thickness. The momentum and energy equations were discretized using finite volume method and solved by employing SIMPLER algorithm. Numerical results were presented for various solid-fluid conductivity ratios (KR) and various values of eccentricities in different thickness of inner cylinder wall and also for different angular positions of inner cylinder. From the results, it was observed that in an eccentric case, and for KR 10 value caused an increase in overline{{K_{eq} }} . It was also concluded that in any angular position of inner cylinder, the value of overline{{K_{eq} }} increased with increase in the eccentricity.

  16. Conjugation, characterization and toxicity of lipophosphoglycan-polyacrylic acid conjugate for vaccination against leishmaniasis

    OpenAIRE

    Topuzogullari, Murat; Cakir Koc, Rabia; Dincer Isoglu, Sevil; Bagirova, Melahat; Akdeste, Zeynep; Elcicek, Serhat; Oztel, Olga N.; Yesilkir Baydar, Serap; Canim Ates, Sezen; Allahverdiyev, Adil M

    2013-01-01

    Research on the conjugates of synthetic polyelectrolytes with antigenic molecules, such as proteins, peptides, or carbohydrates, is an attractive area due to their highly immunogenic character in comparison to classical adjuvants. For example, polyacrylic acid (PAA) is a weak polyelectrolyte and has been used in several biomedical applications such as immunological studies, drug delivery, and enzyme immobilization. However, to our knowledge, there are no studies that document immune-stimulant...

  17. Coexistence of Self-pumped Phase Conjugation and Mutual-pumped Phase Conjugation in Ce∶BaTiO3

    Institute of Scientific and Technical Information of China (English)

    SHE Weilong; Lee Wing-Kee

    2000-01-01

    Self-pumped phase conjugation(SPPC) and mutual-pumped phase conjugation (MPPC) have been found to coexist in Ce∶BaTiO3 by using two coherent beams of 514.5nm wavelength from an argon ion laser. Both phase conjugations are of the stimulated backscattering and four-wave mixing type. For 7/6 incident power ratio and 26 mW total incident power,he shortest phase conjugate mirror formation time is 10s . Phase conjugate reflectivity of one the beams can reach 70%,hich is ~20% higher than the SPPC reflectivity using only one beam. When the total incident power is increased to 40 mW and the incident power ratio remains constant,a maximum phase conjugatate reflectivity of as much as 88% is obtained.

  18. Combretastatin A-4 Conjugated Antiangiogenic Micellar Drug Delivery Systems Using Dendron-Polymer Conjugates.

    Science.gov (United States)

    Sumer Bolu, Burcu; Manavoglu Gecici, Ece; Sanyal, Rana

    2016-05-01

    Employment of polymeric nanomaterials in cancer therapeutics is actively pursued since they often enable drug administration with increased efficacy along with reduced toxic side effects. In this study, drug conjugated micellar constructs are fabricated using triblock dendron-linear polymer conjugates where a hydrophilic linear polyethylene glycol (PEG) chain is flanked by well-defined hydrophobic biodegradable polyester dendrons bearing an antiangiogenic drug, combretastatin-A4 (CA4). Variation in dendron generation is utilized to obtain a library of micellar constructs with varying sizes and drug loadings. In particular, a family of drug appended dendron-polymer conjugates based on polyester dendrons of generations ranging from G1 to G3 and 10 kDa linear PEG were obtained using [3 + 2] Huisgen type "click" chemistry. The final constructs benefit from PEG's hydrophilicity and antibiofouling character, as well as biodegradable nature of the hydrophobic polyester dendrons. The hydrophobic-hydrophilic-hydrophobic character of these constructs leads to the formation of flower-like micelles in aqueous media. In addition to generation-dependent subnanomolar range critical micelle concentrations, the resulting micelles possess hydrodynamic diameters suitable for passive tumor targeting through enhanced permeability and retention (EPR) effect; thereby they are suitable candidates as controlled drug delivery agents. For all constructs, in vitro cytotoxicities were investigated and inhibitory effect of Comb-G3-PEG on tube formation was shown on human umbilical vein endothelial cells (HUVECs). PMID:27019335

  19. Doxorubicin-loaded phosphatidylethanolamine-conjugated nanoliposomes: in vitro characterization and their accumulation in liver, kidneys, and lungs in rats

    Directory of Open Access Journals (Sweden)

    Anandamoy Rudra

    2010-10-01

    Full Text Available Anandamoy Rudra, R Manasa Deepa, Miltu Kumar Ghosh, Subhajit Ghosh, Biswajit MukherjeeDepartment of Pharmaceutical Technology, Jadavpur University, Kolkata (Calcutta, IndiaIntroduction: Phosphatidylethanolamine (PE-conjugated nanoliposomes were developed, characterized, and investigated for their accumulation in liver, kidneys, and lungs in rats.Methods: Drug-excipient interaction was studied using Fourier transform infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, surface morphology by field emission scanning electron microscopy, elemental analysis by energy dispersive X-ray (EDX analysis, zeta potential and size distribution using a Zetasizer and particle size analyzer, and in vitro drug release by dialysis membrane. In vivo accumulation of liposomes in tissues was also studied.Results: No chemical reaction was observed between drug and excipients. EDX study confirmed PE-conjugation in liposomes. Doxorubicin-loaded liposomes (DOX-L and PE-conjugated doxorubicin-loaded liposomes (DOX-PEL were of smooth surface and homogenously distributed in nanosize range (32–37 nm with a negative surface charge. Loading efficiencies were 49.25% ± 1.05% and 52.98% ± 3.22% respectively, for DOX-L and DOX-PEL. In vitro drug release study showed 69.91% ± 1.05% and 77.07% ± 1.02% doxorubicin released, from DOX-L and DOX-PEL, respectively, in nine hours. Fluorescence microscopic study showed that liposomes were well distributed in liver, lungs, and kidneys.Conclusion: Data suggests that PE-conjugated nanoliposomes released the drug in a sustained manner and were capable of distributing them in various organs. This may be used for cell/ tissue targeting, attaching specific antibodies to PE.Keywords: doxorubicin, phosphatidylethanolamine-conjugated nanoliposomes, tissue accumulation

  20. Observation of quantum interference in molecular charge transport

    DEFF Research Database (Denmark)

    Guedon, Constant M.; Valkenier, Hennie; Markussen, Troels;

    2012-01-01

    , phenomena such as giant magnetoresistance(5), Kondo effects(6) and conductance switching(7-11) have been observed in single molecules, and theorists have predicted that it should also be possible to observe quantum interference in molecular conductors(12-18), but until now all the evidence for such...... behaviour has been indirect. Here, we report the observation of destructive quantum interference in charge transport through two-terminal molecular junctions at room temperature. We studied five different rigid p-conjugated molecular wires, all of which form self-assembled monolayers on a gold surface, and...

  1. Price Based Electric Vehicle Charging

    DEFF Research Database (Denmark)

    Mahat, Pukar; Handl, Martin; Kanstrup, Kenneth;

    2012-01-01

    paper investigates the impact on a Danish distribution system when the EV charging aims to reduce the charging cost by charging at the cheapest hours. Results show that the charging based on the price signal only will have adverse effect on the grid. The paper also proposes an alternate EV charging...

  2. Dual Drug Conjugate Loaded Nanoparticles for the Treatment of Cancer.

    Science.gov (United States)

    Matlapudi, Megha Shyam; Moin, Afrasim; Medishetti, Raghavender; Rajendra, K; Raichur, Ashok M; Kumar, B R Prashantha

    2015-01-01

    Two antineoplastic agents, Imatinib (IM) and 5-Fluorouracil (FU) were conjugated by hydrolysable linkers through an amide bond and entrapped in polymeric Human Serum Albumin (HSA) nanoparticles. The presence of dual drugs in a common carrier has the advantage of reaching the site of action simultaneously and acting at different phases of the cell cycle to arrest the growth of cancer cells before they develop chemoresistance. The study has demonstrated an enhanced anticancer activity of the conjugate, and conjugate loaded stealth HSA nanoparticles (NPs) in comparison to the free drug in A-549 human lung carcinoma cell line and Zebra fish embryos (Danio rerio). Hydrolysability of the conjugate has also been demonstrated with complete hydrolysis being observed after 12 h. In vivo pharmacodynamics study in terms of tumor volume and pharmacokinetics in mice for conjugate (IM-SC-FU) and conjugate loaded nanoparticles showed significant anti-cancer activity. The other parameters evaluated were particle size (86nm), Poly Dispersive Index (PDI) (0.209), zeta potential (-49mV), drug entrapment efficiency (96.73%) and drug loading efficiency (89%). Being in stealth mode gives the potential for the NPs to evade Reticulo-Endothelial system (RES), achieve passive targeting by Enhanced Permeation Retention (EPR) effect with controlled release of the therapeutic agent. As the conjugate cleaves into individual drugs in the tumor environment, this promises better suppression of cancer chemoresistance by delivering dual drugs with different modes of action at the same site, thereby synergistically inhibiting the growth of cancerous tissue. PMID:25961796

  3. Synthesis and antimicrobial activity of gold nanoparticle conjugates with cefotaxime

    Science.gov (United States)

    Titanova, Elena O.; Burygin, Gennady L.

    2016-04-01

    Gold nanoparticles (GNPs) have attracted significant interest as a novel platform for various applications to nanobiotechnology and biomedicine. The conjugates of GNPs with antibiotics and antibodies were also used for selective photothermal killing of protozoa and bacteria. Also the conjugates of some antibiotics with GNPs decreased the number of bacterial growing cells. In this work was made the procedure optimization for conjugation of cefotaxime (a third-generation cephalosporin antibiotic) with GNPs (15 nm) and we examined the antimicrobial properties of this conjugate to bacteria culture of E. coli K-12. Addition of cefotaxime solution to colloidal gold does not change their color and extinction spectrum. For physiologically active concentration of cefotaxime (3 μg/mL), it was shown that the optimum pH for the conjugation was more than 9.5. A partial aggregation of the GNPs in saline medium was observed at pH 6.5-7.5. The optimum concentration of K2CO3 for conjugation cefotaxime with GNPs-15 was 5 mM. The optimum concentration of cefotaxime was at 0.36 μg/mL. We found the inhibition of the growth of E. coli K12 upon application cefotaxime-GNP conjugates.

  4. Decay of electric charge on corona charged polyethylene

    International Nuclear Information System (INIS)

    This paper describes a study on the surface potential decay of corona charged low density polyethylene (LDPE) films. A conventional corona charging process is used to deposit charge on the surface of film and surface potential is measured by a compact JCI 140 static monitor. The results from corona charged multilayer sample reveal that the bulk process dominates charge decay. In addition, the pulsed-electro-acoustic (PEA) technique has been employed to monitor charge profiles in corona charged LDPE films. By using the PEA technique, we are able to monitor charge migration through the bulk. Charge profiles in corona charged multilayer sample are consistent with surface potential results. Of further significance, the charge profiles clearly demonstrate that double injection has taken place in corona charged LDPE films

  5. Imidazole as a Donor/Acceptor Unit in Charge-Transfer Chromophores with Extended pi-Linkers

    Czech Academy of Sciences Publication Activity Database

    Kulhánek, J.; Bureš, F.; Pytela, O.; Mikysek, T.; Ludvík, Jiří

    2011-01-01

    Roč. 6, č. 6 (2011), s. 1604-1612. ISSN 1861-4728 Institutional research plan: CEZ:AV0Z40400503 Keywords : charge transfer * conjugation * donor-acceptor systems Subject RIV: CG - Electrochemistry Impact factor: 4.500, year: 2011

  6. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion

    Science.gov (United States)

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

    2016-08-01

    Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.

  7. Molecular and structural insight into lysine selection on substrate and ubiquitin lysine 48 by the ubiquitin-conjugating enzyme Cdc34

    DEFF Research Database (Denmark)

    Suryadinata, Randy; Holien, Jessica K; Yang, George; Parker, Michael W.; Papaleo, Elena; Šarčević, Boris

    2013-01-01

    The attachment of ubiquitin (Ub) to lysines on substrates or itself by ubiquitin-conjugating (E2) and ubiquitin ligase (E3) enzymes results in protein ubiquitination. Lysine selection is important for generating diverse substrate-Ub structures and targeting proteins to different fates; however, the...... mechanisms of lysine selection are not clearly understood. The positioning of lysine(s) toward the E2/E3 active site and residues proximal to lysines are critical in their selection. We investigated determinants of lysine specificity of the ubiquitin-conjugating enzyme Cdc34, toward substrate and Ub lysines....... Evaluation of the relative importance of different residues positioned -2, -1, +1 and +2 toward ubiquitination of its substrate, Sic1, on lysine 50 showed that charged residues in the -1 and -2 positions negatively impact on ubiquitination. Modeling suggests that charged residues at these positions alter the...

  8. Current Status: Site-Specific Antibody Drug Conjugates.

    Science.gov (United States)

    Schumacher, Dominik; Hackenberger, Christian P R; Leonhardt, Heinrich; Helma, Jonas

    2016-05-01

    Antibody drug conjugates (ADCs), a promising class of cancer biopharmaceuticals, combine the specificity of therapeutic antibodies with the pharmacological potency of chemical, cytotoxic drugs. Ever since the first ADCs on the market, a plethora of novel ADC technologies has emerged, covering as diverse aspects as antibody engineering, chemical linker optimization and novel conjugation strategies, together aiming at constantly widening the therapeutic window for ADCs. This review primarily focuses on novel chemical and biotechnological strategies for the site-directed attachment of drugs that are currently validated for 2nd generation ADCs to promote conjugate homogeneity and overall stability. PMID:27003914

  9. Conjugation vs hyperconjugation in molecular structure of acrolein

    Science.gov (United States)

    Shishkina, Svitlana V.; Slabko, Anzhelika I.; Shishkin, Oleg V.

    2013-01-01

    Analysis of geometric parameters of butadiene and acrolein reveals the contradiction between the Csp2-Csp2 bond length in acrolein and classical concept of conjugation degree in the polarized molecules. In this Letter the reasons of this contradiction have been investigated. It is concluded that the Csp2-Csp2 bond length in acrolein is determined by influence of the bonding for it π-π conjugation and antibonding n → σ∗ hyperconjugation between the oxygen lone pair and the antibonding orbital of the single bond. It was shown also this bond length depends on the difference in energy of conjugative and hyperconjugative interactions.

  10. Detoxications in peripatus. Sulphate, phosphate and histidine conjugations.

    Science.gov (United States)

    Jordan, T W; McNaught, R W; Smith, J N

    1970-06-01

    Phenols were detoxified in the Onycophoran Peripatoides novaezealandiae by conjugation with sulphuric acid and phosphoric acid, but no evidence for a glycoside detoxication could be found. [(14)C]Benzoic acid was metabolized in 24h to N(2)-benzoyl-l-histidine, which was identified by electrophoresis, chromatography and dilution analysis. Similar conjugates were formed with p-aminobenzoic acid and p-nitrobenzoic acid. In longer-duration experiments further unidentified metabolites were formed, two of which appeared to result from the further metabolism of the histidine conjugate. PMID:5472152

  11. Phase conjugation metamaterials: particle design and imaging experiments

    International Nuclear Information System (INIS)

    We present simulation and experimental results demonstrating the effectiveness of phase conjugation or, equivalently, time reversal metamaterials for imaging applications. Split-ring resonators are loaded with varactor diodes to enable straightforward, easy-to-fabricate phase conjugation metamaterial unit cells. These cells are improved upon to allow either completely wireless operation or more efficient phase conjugate signal generation through the use of active loading elements. The metamaterials are demonstrated experimentally to produce time reversed signals with useful properties. An array of metamaterial cells is then constructed and shown to act as a negatively refracting imaging system. (paper)

  12. Electric charge quantization

    International Nuclear Information System (INIS)

    Experimentally it has been known for a long time that the electric charges of the observed particles appear to be quantized. An approach to understanding electric charge quantization that can be used for gauge theories with explicit U(1) factors - such as the standard model and its variants - is pedagogically reviewed and discussed in this article. This approach used the allowed invariances of the Lagrangian and their associated anomaly cancellation equations. It is demonstrated that charge may be de-quantized in the three-generation standard model with massless neutrinos, because differences in family-lepton-numbers are anomaly-free. The relevant experimental limits are also reviewed. This approach to charge quantization suggests that the minimal standard model should be extended so that family-lepton-number differences are explicitly broken. Some candidate extensions such as the minimal standard model augmented by Majorana right-handed neutrinos are also briefly discussed. 30 refs

  13. Primitive Virtual Negative Charge

    CERN Document Server

    Kim, Kiyoung

    2008-01-01

    Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction electric equilibrium of the earth is discussed, especially about the electric field and magnetic field of the earth. For unsettled phenomena related with the earth's gravity, such as antigravity phenomenon, gravity anomalies during the solar eclipses, the connection between geomagnetic storms and earthquakes, etc., possible explanations are discussed.

  14. Space-Charge Effect

    CERN Document Server

    Chauvin, N

    2013-01-01

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

  15. Conjugated organometallic materials containing tungsten centers

    Science.gov (United States)

    Jones, Marya

    Our group is interested in the optical and electronic properties of organometallic analogues of conjugated organic compounds. Specifically, in this thesis we will discuss the properties of complexes in which W≡C moieties replace C≡C fragments within the framework of oligo(phenyleneethynylenes) and a C4-polyyne. A family of derivatives of the type Ph(C≡CC6H4 )m(L)4W≡C(C6H 4C≡C)nPh (m = 0, 1; n = 0, 1, 2) have been prepared and characterized by X-ray crystallography, electronic-absorption spectroscopy, and electrochemistry. This substitution has allowed us to directly compare the electronic and optical properties of these organometallic complexes with those of their organic analogues. We found that while these systems exhibit redox and spectroscopic properties similar to those of their organic counterparts they also exhibit new characteristics that are due to the incorporation of the metal center. The design of these compounds has also allowed us to address how the position of the metal within the backbone affects the electronic and optical properties of these compounds. We found that the position of the metal is important in controlling the electronic structure of the material, thus suggesting that the properties of these compounds can be further tuned by changing the position of the metal within the conjugated carbon chain. In addition, we have appended sulfur and isocyanide functionalities to oligo(phenyleneethynylene) analogues. A family of compounds of the type Cl(dppe) 2W(≡CC6H4-4-(C≡CC6H 4)m-4'-R) (m = l, 2; R = N≡C, SCH2CH 2Si(CH3)3) have been prepared and characterized by electronic-absorption spectroscopy and electrochemistry. Differences between the sulfur and isocyanide functionalities are examined, along with the effects of extending conjugation along the arylidyne chain. Evidence that the sulfur-containing arylidyne complexes form self-assembled monolayers on Au and Pt electrodes is presented. In addition, the electron-transfer rates for

  16. The Gas-Phase Photophysics of Eosin Y and its Maleimide Conjugate.

    Science.gov (United States)

    Daly, Steven; Kulesza, Alexander; Knight, Geoffrey; MacAleese, Luke; Antoine, Rodolphe; Dugourd, Philippe

    2016-05-26

    The use of the xanthene family of dyes as fluorescent probes in a wide range of applications has provided impetus for the studying of their photophysical properties. In particular, recent advances in gas-phase techniques such as FRET that utilize such chromophores have placed a greater importance on the characterization of these properties in the gas phase. Additionally, the use of synthetic linker chains to graft the chromophores in a site-specific manner to their target system is ubiquitous. There is, however, often limited information on how the addition of such a linker chain may affect the photophysical properties of the chromophores, which is of fundamental importance for interpretation of experimental data reliant on grafted chromophores. Here, we present data on the optical spectroscopy of different protonation states of Eosin Y, a fluorescein derivative. We compare the photophysics of Eosin Y to its maleimide conjugate, and to the thioether product of the reaction of this conjugate with cysteamine. Comparison of the mass spectra following laser irradiation shows that very different relaxation takes place upon addition of the maleimide moiety but that the photophysics of the bare chromophore are restored upon addition of cysteamine. This radical change in the photophysics is interpreted in terms of charge-transfer states, whose energy relative to the S1 ← S0 transition of the chromophore is dependent on the conjugation of the maleimide moiety. We also show that the shape of the absorption band is unchanged in the gas-phase as compared to the solution-phase, showing a maximum with a shoulder toward the blue, and examination of isotope distributions of the isolated ions show that this shoulder cannot be due to the presence of dimers. Consideration of the fluorescence emission spectrum allows a tentative assignment of the shoulder to be due to a vibrational progression with a high Franck-Condon factor. PMID:27118657

  17. Charge-sensitive amplifier

    OpenAIRE

    Startsev V. I.; Yampolsky Ju. S.

    2008-01-01

    The authors consider design and circuit design techniques of reduction of the influence of the pyroelectric effect on operation of the charge sensitive amplifiers. The presented experimental results confirm the validity of the measures taken to reduce the impact of pyroelectric currents. Pyroelectric currents are caused by the influence of the temperature gradient on the piezoelectric sensor and on the output voltage of charge sensitive amplifiers.

  18. MOSFET Electric-Charge Sensor

    Science.gov (United States)

    Robinson, Paul A., Jr.

    1988-01-01

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

  19. Gaseous charge transfer reactions of multiply charged ions

    International Nuclear Information System (INIS)

    Doubly charged ions produced in electron impact ionization have received relatively little study due to their low abundance and masking from singly charged ions which are detected at the same mass-to-charge ratio by a mass spectrometer. This interference problem was avoided by exploiting a technique in which doubly charged molecular and fragment ions are monitored using a collisional charge-exchange process where only fast singly charged product ions are allowed to reach the detector. Primary research efforts were to determine structures and energetics of multiply charged ions formed in high energy electron impact ionization processes and their reactivities in ion-molecule charge exchange interactions. Doubly charged ion mass distributions for various chemical classes (including acetylenes, alkenes, terpenes and organophosphorus compounds) were recorded and appearance energies of prominent doubly charged ions were measured. Computer molecular orbital calculations (at the MINDO/3 level) of ionic structures, energies and charge distributions were utilized to augment the analysis of experimental results

  20. Stabilization of Charge Carriers in Picket-Fence Polythiophenes Using Dielectric Side Chains.

    Science.gov (United States)

    Zhao, Chunhui; Sakurai, Tsuneaki; Yoneda, Satoru; Seki, Shu; Sugimoto, Manabu; Oki, Choji; Takeuchi, Masayuki; Sugiyasu, Kazunori

    2016-08-19

    Insulated molecular wires (IMWs) are π-conjugated polymers that are molecularly sheathed with an insulating layer and are structurally analogous to electric power cords at the nanoscale. Such unique architectures are expected in molecular electronics and organic devices. Herein, we propose a new molecular design concept of IMWs, in which the sheaths can be customized, thereby enabling the modulation of the electronic properties of the interior π-conjugated systems. To this end, we focused our attention on the dielectric constant of the sheaths, as it governs the electrostatic interaction between charges. Upon doping, charge carriers, such as polaron and bipolaron, were generated regardless of the dielectric properties of the sheaths. Flash-photolysis time-resolved microwave conductivity measurements revealed that intrawire charge carrier mobility was independent of the sheaths. However, we found that the charge carriers could be stabilized by the sheaths with a high dielectric constant owing to the charge screening effect. We expect that IMWs designed in this way will be useful in a variety of applications, where the nature of charge carriers plays an important role, and particularly when redox switching is required (e.g., electrochromic, magnetic, and memory applications). PMID:27503254

  1. Effect of introduction of chondroitin sulfate into polymer-peptide conjugate responding to intracellular signals

    Science.gov (United States)

    Tomiyama, Tetsuro; Toita, Riki; Kang, Jeong-Hun; Koga, Haruka; Shiosaki, Shujiro; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

    2011-09-01

    We recently developed a novel tumor-targeted gene delivery system responding to hyperactivated intracellular signals. Polymeric carrier for gene delivery consists of hydrophilic neutral polymer as main chains and cationic peptide substrate for target enzyme as side chains, and was named polymer-peptide conjugate (PPC). Introduction of chondroitin sulfate (CS), which induces receptor-medicated endocytosis, into polymers mainly with a high cationic charge density such as polyethylenimine can increase tumor-targeted gene delivery. In the present study, we examined whether introduction of CS into PPC containing five cationic amino acids can increase gene expression in tumor cells. Size and zeta potential of plasmid DNA (pDNA)/PPC/CS complex were stability and gene regulation, compared with that of pDNA/PPC. Moreover, no difference in gene expression was identified between positive and negative polymer. These results were caused by fast disintegration of pDNA/PPC/CS complexes in the presence of serum. Thus, we suggest that introduction of negatively charged CS into polymers with a low charge density may lead to low stability and gene regulation of complexes.

  2. A conserved helicase processivity factor is needed for conjugation and replication of an integrative and conjugative element

    OpenAIRE

    Thomas, Jacob; Lee, Catherine A.; Grossman, Alan D.

    2012-01-01

    Integrative and conjugative elements (ICEs) are agents of horizontal gene transfer and have major roles in evolution and acquisition of new traits, including antibiotic resistances. ICEs are found integrated in a host chromosome and can excise and transfer to recipient bacteria via conjugation. Conjugation involves nicking of the ICE origin of transfer (oriT) by the ICE–encoded relaxase and transfer of the nicked single strand of ICE DNA. For ICEBs1 of Bacillus subtilis, nicking of oriT by th...

  3. Spontaneous Charge Carrier Localization in Extended One-Dimensional Systems

    Science.gov (United States)

    Vlček, Vojtěch; Eisenberg, Helen R.; Steinle-Neumann, Gerd; Neuhauser, Daniel; Rabani, Eran; Baer, Roi

    2016-05-01

    Charge carrier localization in extended atomic systems has been described previously as being driven by disorder, point defects, or distortions of the ionic lattice. Here we show for the first time by means of first-principles computations that charge carriers can spontaneously localize due to a purely electronic effect in otherwise perfectly ordered structures. Optimally tuned range-separated density functional theory and many-body perturbation calculations within the G W approximation reveal that in trans-polyacetylene and polythiophene the hole density localizes on a length scale of several nanometers. This is due to exchange-induced translational symmetry breaking of the charge density. Ionization potentials, optical absorption peaks, excitonic binding energies, and the optimally tuned range parameter itself all become independent of polymer length as it exceeds the critical localization length. Moreover, we find that lattice disorder and the formation of a polaron result from the charge localization in contrast to the traditional view that lattice distortions precede charge localization. Our results can explain experimental findings that polarons in conjugated polymers form instantaneously after exposure to ultrafast light pulses.

  4. Valence Topological Charge-Transfer Indices for Dipole Moments

    Directory of Open Access Journals (Sweden)

    Francisco Torrens

    2003-01-01

    Full Text Available New valence topological charge-transfer indices are applied to the calculation of dipole moments. The algebraic and vector semisum charge-transfer indices are defined. The combination of the charge-transfer indices allows the estimation of the dipole moments. The model is generalized for molecules with heteroatoms. The ability of the indices for the description of the molecular charge distribution is established by comparing them with the dipole moments of a homologous series of phenyl alcohols. Linear and non-linear correlation models are obtained. The new charge-transfer indices improve the multivariable non-linear regression equations for the dipole moment. When comparing with previous results, the variance decreases 92%. No superposition of the corresponding Gk–Jk and GkV – JkV pairs is observed. This diminishes the risk of co-linearity. Inclusion of the oxygen atom in the p-electron system is beneficial for the description of the dipole moment, owing to either the role of the additional p orbitals provided by the heteroatom or the role of steric factors in the p-electron conjugation. Linear and non-linear correlations between the fractal dimension and various descriptors point not only to a homogeneous molecular structure but also to the ability to predict and tailor drug properties.

  5. Water/alcohol soluble conjugated polymers as highly efficient electron transporting/injection layer in optoelectronic devices.

    Science.gov (United States)

    Huang, Fei; Wu, Hongbin; Cao, Yong

    2010-07-01

    Water/alcohol soluble conjugated polymers (WSCPs) can be processed from water or other polar solvents, which offer good opportunities to avoid interfacial mixing upon fabrication of multilayer polymer optoelectronic devices by solution processing, and can dramatically improve charge injection from high work-function metal cathode resulting in greatly enhancement of the device performance. In this critical review, the authors provide a brief review of recent developments in this field, including the materials design, functional principles, and their unique applications as interface modification layer in solution-processable multilayer optoelectronic devices (135 references). PMID:20571672

  6. Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

    Directory of Open Access Journals (Sweden)

    Florian Massuyeau

    2015-05-01

    Full Text Available The mechanisms that control the photophysics of composite films made of a semiconducting conjugated polymer (poly(paraphenylene vinylene, PPV mixed with single-walled carbon nanotubes (SWNT up to a concentration of 64 wt % are determined by using photoexcitation techniques and density functional theory. Charge separation is confirmed experimentally by rapid quenching of PPV photoluminescence and changes in photocurrent starting at relatively low concentrations of SWNT. Calculations predict strong electronic interaction between the polymer and the SWNT network when nanotubes are semiconducting.

  7. Effect of the Pauli exclusion principle on the singlet exciton yield in conjugated polymers

    Science.gov (United States)

    Thilagam, A.

    2016-03-01

    Optical devices fabricated using conjugated polymer systems give rise to singlet exciton yields which are high compared to the statistically predicted estimate of 25 % obtained using simple recombination schemes. In this study, we evaluate the singlet exciton yield in conjugated polymers systems by fitting to a model that incorporates the Pauli exclusion principle. The rate equations which describe the exciton dynamics include quantum dynamical components (both density and spin-dependent) which arise during the spin-allowed conversion of composite intra-molecular excitons into loosely bound charge-transfer (CT) electron-hole pairs. Accordingly, a crucial mechanism by which singlet excitons are increased at the expense of triplet excitons is incorporated in this work. Non-ideal triplet excitons which form at high densities, are rerouted via the Pauli exclusion mechanism to form loosely bound CT states which subsequently convert to singlet excitons. Our derived expression for the yield in singlet exciton incorporates the purity measure and provides a realistic description of the carrier dynamics at high exciton densities.

  8. Phase conjugation of gap solitons: A numerical study

    Indian Academy of Sciences (India)

    V S C Manga Rao; S Dutta Gupta

    2003-09-01

    We study the effect of a nearby phase-conjugate mirror (PCM) on the gap soliton of a Kerr non-linear periodic structure. We show that phase conjugation of the gap soliton (in the sense of replication of the amplitude profile in the reverse direction) is possible under the condition of PCM reflectivity approaching unity. This is in contrast with the results for linear structures, where the wave profiles can be conjugated for arbitrary values of the PCM reflectivity. The sensitivity of the conjugation of the gap solitons to PCM reflectivity is ascribed to the fine balance of non-linearity with dispersion, necessary for their existence.

  9. Preparation of Conjugated Linoleic Acid and Identification of Its Isomers

    Institute of Scientific and Technical Information of China (English)

    郭诤; 张根旺; 孙彦

    2003-01-01

    Conjugated linoleic acid(CLA)is a kind of fatty acid with physiological activities and potential appli-cation prospect ,A synthesis method of conjugated linoleic acid and a purification technology were studied .CLA was prepared and purified by urea-complexation and conjugation using safflower oil as raw material,The purity of CLA and total recovery of the product was more than 95% and 48%,respectively,The main isomers produced in alkali-catalyzed conjugation were identified by gas chromatography (GC)linked to mass spectrometry(MS) and Fourier transform infrared spectroscopy(FTIR),The total amount of the two main isomers (9cis,11trans-and 10trans,12cis-CLA) determined by GC was more than 90% of the product.

  10. QM/MM-MD simulations of conjugated polyelectrolytes

    DEFF Research Database (Denmark)

    Sjöqvist, Jonas; Linares, Mathieu; Mikkelsen, Kurt Valentin;

    2014-01-01

    A methodological development is reported for the study of luminescence properties of conjugated polyelectrolytes, encompassing systems in which dihedral rotational barriers are easily overcome at room temperature. The components of the model include (i) a molecular mechanics (MM) force field...

  11. Fluorescence array-based sensing of nitroaromatics using conjugated polyelectrolytes.

    Science.gov (United States)

    Wu, Jiatao; Tan, Chunyan; Chen, Zhifang; Chen, Yu Zong; Tan, Ying; Jiang, Yuyang

    2016-05-23

    A sensor array consisting of six cationic fluorescent conjugated polyelectrolytes (CPEs) is reported, which could readily differentiate between nine closely related hydrophilic nitroaromatics (NACs) in separate aqueous solutions by fluorescence pattern recognition and linear discrimination analysis (LDA). PMID:27169808

  12. Partial Hermitian Conjugate Separability Criteria for Pure Quantum States

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin; WU Hua; LI Yan-Song; LONG Gui-Lu

    2009-01-01

    We propose a criterion for the separability of quantum pure states using the concept of a partial Hermitian conjugate.It is equivalent to the usual positive partial transposition criteria,with a simple physical interpretation.

  13. Biomedical Applications of DNA-Conjugated Gold Nanoparticles.

    Science.gov (United States)

    Wang, Chun-Chi; Wu, Shou-Mei; Li, Hung-Wen; Chang, Huan-Tsung

    2016-06-16

    Gold nanoparticles (AuNPs) are useful for diagnostic and biomedical applications, mainly because of their ease in preparation and conjugation, biocompatibility, and size-dependent optical properties. However, bare AuNPs do not possess specificity for targets. AuNPs conjugated with DNA aptamers offer specificity for various analytes, such as proteins and small molecules/ions. Although DNA aptamers themselves have therapeutic and target-recognizing properties, they are susceptible to degradation in vivo. When DNA aptamers are conjugated to AuNPs, their stability and cell uptake efficiency both increase, making aptamer-AuNPs suitable for biomedical applications. Additionally, drugs can be efficiently conjugated with DNA aptamer-AuNPs to further enhance their therapeutic efficiency. This review focuses on the applications of DNA aptamer-based AuNPs in several biomedical areas, including anticoagulation, anticancer, antibacterial, and antiviral applications. PMID:26864481

  14. Partial Hermitian Conjugate Separability Criteria for Pure Quantum States

    International Nuclear Information System (INIS)

    We propose a criterion for the separability of quantum pure states using the concept of a partial Hermitian conjugate. It is equivalent to the usual positive partial transposition criteria, with a simple physical interpretation. (general)

  15. Conjugation by Mosquito Pathogenic Strains of Bacillus sphaericus

    Directory of Open Access Journals (Sweden)

    Correa Margarita

    1997-01-01

    Full Text Available A mosquito pathogenic strain of Bacillus sphaericus carried out the conjugal transfer of plasmid pAMß1 to other strains of its own and two other serotypes. However, it was unable to conjugate with mosquito pathogens from three other serotypes, with B. sphaericus of other DNA homology groups or with three other species of Bacillus. Conjugation frequency was highest with a strain having an altered surface layer (S layer. Conjugal transfer of pAMß1 was not detected in mosquito larval cadavers. B. sphaericus 2362 was unable to mobilize pUB110 for transfer to strains that had served as recipients of pAMß1. These observations suggest that it is unlikely that genetically engineered B. sphaericus carrying a recombinant plasmid could pass that plasmid to other bacteria

  16. Polylactide Conjugates of Camptothecin with Different Drug Release Abilities

    Directory of Open Access Journals (Sweden)

    Ewa Oledzka

    2014-11-01

    Full Text Available Camptothecin-polylactide conjugates (CMPT-PLA were synthesized by covalent incorporation of CMPT into PLA of different microstructure, i.e., atactic PLA and atactic-block-isotactically enriched PLA (Pm = 0.79 via urethane bonds. The kinetic release of CPMT from CMPT-PLA conjugates, tested in vitro under different conditions, is possible in both cases and notably, strongly dependent on PLA microstructure. It shows that release properties of drug-PLA conjugates can be tailored by controlled design of the PLA microstructure, and allow in the case of CMPT-PLA conjugates for the development of highly controlled biodegradable CMPT systems—important delivery systems for anti-cancer agents.

  17. Theory of Periodic Conjugate Heat Transfer

    CERN Document Server

    Zudin, Yuri B

    2012-01-01

    This book presents the theory of periodic conjugate heat transfer in a detailed way. The effects of thermophysical properties and geometry of a solid body on the commonly used and experimentally determined heat transfer coefficient are analytically presented from a general point of view. The main objective of the book is a simplified description of the interaction between a solid body and a fluid as a boundary value problem of the heat conduction equation for the solid body. At the body surface, the true heat transfer coefficient is composed of two parts: the true mean value resulting from the solution of the steady state heat transfer problem and a periodically variable part, the periodic time and length to describe the oscillatory hydrodynamic effects. The second edition is extended by (i) the analysis of stability boundaries in helium flow at supercritical conditions in a heated channel with respect to the interaction between a solid body and a fluid; (ii) a periodic model and a method of heat transfer sim...

  18. Stellar photometry with Multi Conjugate Adaptive Optics

    CERN Document Server

    Fiorentino, Giuliana; McConnachie, Alan; Stetson, Peter B; Bono, Giuseppe; Turri, Paolo; Andersen, David; Veran, Jean-Pierre; Diolaiti, Emiliano; Schreiber, Laura; Ciliegi, Paolo; Bellazzini, Michele; Tolstoy, Eline; Monelli, Matteo; Iannicola, Giacinto; Ferraro, Ivan; Testa, Vincenzo

    2016-01-01

    We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stellar population studies. Stars in crowded stellar systems, such as globular clusters or in nearby galaxies, are ideal test particles to test AO performance. We will focus the discussion on photometric precision and accuracy reached nowadays. We briefly describe our project on stellar photometry and astrometry of Galactic globular clusters using images taken with GeMS at the Gemini South telescope. We also present the photometry performed with DAOPHOT suite of programs into the crowded regions of these globulars reaching very faint limiting magnitudes Ks ~21.5 mag on moderately large fields of view (~1.5 arcmin squared). We highlight the need for new algorithms to improve the modeling of the complex variation of the Point Spread Function across the ?eld of view. Finally, we outl...

  19. Microfluidic Fabrication of Conjugated Polymer Sensor Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Imsung; Song, Simon [Hanyang University, Seoul (Korea, Republic of)

    2014-10-15

    We propose a fabrication method for polydiacetylene (PDA)-embedded hydrogel microfibers on a microfluidic chip. These fibers can be applied to the detection of cyclodextrines (CDs), which are a family of sugar and aluminum ions. PDA, a family of conjugated polymers, has unique characteristics when used for a sensor, because it undergoes a blue-to-red color transition and nonfluorescence-to-fluorescence transition in response to environmental stimulation. PDAs have different sensing characteristics depending on the head group of PCDA. By taking advantage of ionic crosslinking-induced hydrogel formation and the 3D hydrodynamic focusing effect on a microfluidic chip, PCDA-EDEA-derived diacetylene (DA) monomer-embedded microfibers were successfully fabricated. UV irradiation of the fibers afforded blue-colored PDA, and the resulting blue PDA fibers underwent a phase transition to red and emitted red fluorescence upon exposure to CDs and aluminum ions. Their fluorescence intensity varied depending on the CDs and aluminum ion concentrations. This phase transition was also observed when the fibers were dried.

  20. Optimization of PAMAM-gold nanoparticle conjugation for gene therapy

    OpenAIRE

    Figueroa, Elizabeth R.; Lin, Adam Y.; Yan, Jiaxi; Luo, Laureen; Foster, Aaron E.; Drezek, Rebekah A.

    2013-01-01

    The development of efficient and biocompatible non-viral vectors for gene therapy remains a great challenge, and exploiting the properties of both nanoparticle carriers and cationic polymers is an attractive approach. In this work, we have developed gold nanoparticle (AuNP) polyamidoamine (PAMAM) conjugates for use as non-viral transfection agents. AuPAMAM conjugates were prepared by crosslinking PAMAM dendrimers to carboxylic-terminated AuNPs via EDC and sulfo-NHS chemistry. EDC and sulfo-NH...

  1. Antibody–drug conjugates: targeted weapons against cancer

    OpenAIRE

    Scotti, Claudia

    2015-01-01

    Luisa Iamele, Luca Vecchia, Claudia ScottiDepartment of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Pavia, PV, Italy  All authors contributed equally to this work Abstract: Antibody–drug conjugates (ADCs) are formed by a targeting antibody conjugated to a chemotherapeutic molecule through a linker. Recent data demonstrate that ADCs represent a valuable advancement for the clinics and, despite their recent appearance in medicine, they ...

  2. Places and Belongings: Conjugality between Angola and Portugal

    OpenAIRE

    Grassi, Marzia

    2015-01-01

    In the context of contemporary studies of families and transnational lives, this paper sets out the emergence of new forms of conjugality among heterosexual couples living apart (one in Portugal, the other in Angola). Considering the importance of gender stratification we seek to understand how the construction of masculinity is reformulated in the couple when the man migrates to the other country to find work. When a conjugal pair separates as a result of the migration of one ...

  3. Fluorescent non-conjugated polymer dots for targeted cell imaging

    Science.gov (United States)

    Sun, Bin; Zhao, Bin; Wang, Dandan; Wang, Yibo; Tang, Qi; Zhu, Shoujun; Yang, Bai; Sun, Hongchen

    2016-05-01

    Through the chemical crosslinking of the sub-fluorophore, linear non-conjugated polymers can possess strong photoluminescence (PL), which is a very important fluorescence behavior and the non-conjugated polymer dots (PDs) are efficient bio-fluorophores for bio-based applications. Herein, the new type of non-conjugated polyethyleneimine (PEI) PDs was further modified by targeting molecules (folic acid) for a new generation of bio-fluorophores. The free folic acid can quench the PL of PDs by energy transfer, while the conjugated folic acid@PDs (FA@PDs) can still maintain their PL properties to a certain degree. The FA@PDs also possess lower toxicity compared with free PDs, which is possibly due to blocking of the amino groups. Moreover, we investigated the targeted bioimaging applications of the FA@PDs, which gave a very important direction for application of these types of materials.Through the chemical crosslinking of the sub-fluorophore, linear non-conjugated polymers can possess strong photoluminescence (PL), which is a very important fluorescence behavior and the non-conjugated polymer dots (PDs) are efficient bio-fluorophores for bio-based applications. Herein, the new type of non-conjugated polyethyleneimine (PEI) PDs was further modified by targeting molecules (folic acid) for a new generation of bio-fluorophores. The free folic acid can quench the PL of PDs by energy transfer, while the conjugated folic acid@PDs (FA@PDs) can still maintain their PL properties to a certain degree. The FA@PDs also possess lower toxicity compared with free PDs, which is possibly due to blocking of the amino groups. Moreover, we investigated the targeted bioimaging applications of the FA@PDs, which gave a very important direction for application of these types of materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01909a

  4. Impacts of the 13-valent pneumococcal conjugate vaccine in children

    OpenAIRE

    Susanna Esposito; Nicola Principi

    2015-01-01

    Applications of the heptavalent pneumococcal conjugate vaccine (PCV7) in the pediatric immunization schedule have dramatically reduced the incidence of pneumococcal diseases in both vaccinated children and unvaccinated individuals of all ages. However, increased infections caused by non-PCV7 serotypes have been reported by several groups. To overcome this problem, new vaccines covering more serotypes including the emerging serotypes have been developed. The 13-valent pneumococcal conjugate va...

  5. Pneumococcal Conjugate Vaccine for Adults: A New Paradigm

    OpenAIRE

    Paradiso, Peter R

    2012-01-01

    A 13-valent pneumococcal conjugate vaccine has been studied in adults aged ≥50 years to compare the immune response to that induced by the 23-valent pneumococcal polysaccharide vaccine, which has been the standard of care over the past 30 years. The results demonstrate that adults, regardless of whether they are naive or previously vaccinated with the polysaccharide vaccine, have an overall superior antibody response when vaccinated with the conjugate vaccine compared with the pneumococcal po...

  6. Pneumococcal conjugate vaccine in adults: Let's see what happens.

    Science.gov (United States)

    Paradiso, Peter R

    2016-07-01

    The recent recommendation for the use of the 13-valent pneumococcal conjugate vaccine (PCV13) in adults 65 y of age and older, provides a new tool for preventing disease in this at-risk population. The conjugate vaccine induces a T-cell dependent response, which distinguishes it from the polysaccharide vaccine and could provide the longer-term protection necessary to have a significant impact in this population. PMID:26901618

  7. Pneumococcal vaccination of older adults: Conjugate or polysaccharide?

    OpenAIRE

    Fedson, David S; Guppy, Martin J.

    2013-01-01

    Invasive pneumococcal disease continues to be important problem for older adults. Pneumococcal polysaccharide vaccine (PPV23) has a clinical effectiveness of 43–81%, and following primary vaccination and revaccination, antibody responses last 5–10 y. Hyporesponsiveness to a second dose of vaccine has not been shown to be a significant problem. The use of pneumococcal conjugate vaccines (initially PCV7; more recently PCV13) has led to a dramatic fall in the incidence of conjugate vaccine-type ...

  8. Conjugate boundary condition, hidden matters, and gauge-Higgs inflation

    CERN Document Server

    Abe, Yugo; Kawamura, Yoshiharu; Nishikawa, Yasunari

    2016-01-01

    We propose an idea that hidden matters can be separated according to gauge quantum numbers from the visible ones by the difference of boundary conditions on extra dimensions. We formulate 5-dimensional gauge theories yielding conjugate boundary conditions besides ordinary ones on $S^1/Z_2$, and examine physical implications concerning hidden matters on an extension of the standard model coexisting different types of boundary conditions. A model with conjugate boundary conditions is applied on a gauge-Higgs inflation scenario.

  9. A NOTE ON THE NONLINEAR CONJUGATE GRADIENT METHOD

    Institute of Scientific and Technical Information of China (English)

    Yu-hong Dai; Ya-xiang Yuan

    2002-01-01

    The conjugate gradient method for unconstrained optimization problems varies with a scalar. In this note, a general condition concerning the scalar is given, which ensures the global convergence of the method in the case of strong Wolfe line searches. It is also discussed how to use the result to obtain the convergence of the famous Fletcher-Reeves, and Polak-Ribiere-Polyak conjugate gradient methods. That the condition cannot be relaxed in some sense is mentioned.

  10. Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

    Science.gov (United States)

    Wakamatsu, Takamichi; Nagao, Kazunori

    2015-01-01

    Summary A copper-catalyzed conjugate addition of alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) to alkynoates to form β-disubstituted acrylates is reported. The addition occurred in a formal syn-hydroalkylation mode. The syn stereoselectivity was excellent regardless of the substrate structure. A variety of functional groups were compatible with the conjugate addition. PMID:26734092

  11. Precomplete clones on infinite sets which are closed under conjugation

    OpenAIRE

    Pinsker, Michael

    2004-01-01

    We show that on an infinite set, there exist no other precomplete clones closed under conjugation except those which contain all permutations. Since on base sets of some infinite cardinalities, in particular on countably infinite ones, the precomplete clones containing the permutations have been determined, this yields a complete list of the precomplete conjugation-closed clones in those cases. In addition, we show that there exist no precomplete submonoids of the full transformation monoid w...

  12. Biofilm growth alters regulation of conjugation by a bacterial pheromone

    OpenAIRE

    Cook, Laura; Barnes, Aaron; Dunny, Gary; Chatterjee, Anushree; Hu, Wei-Shou; Yarwood, Jeremy

    2011-01-01

    Conjugation is an important mode of horizontal gene transfer in bacteria, enhancing the spread of antibiotic resistance. In clinical settings, biofilms are likely locations for antibiotic resistance transfer events involving nosocomial pathogens such as Enterococcus faecalis. Here we demonstrate that growth in biofilms alters the induction of conjugation by a sex pheromone in E. faecalis. Mathematical modeling suggested that a higher plasmid copy number in biofilm cells would enhance a switch...

  13. Conjugative plasmid transfer from Enterococcus faecalis to Escherichia coli.

    OpenAIRE

    Trieu-Cuot, P; Carlier, C; Courvalin, P

    1988-01-01

    The possibility of transfer of genetic information by conjugation from gram-positive to gram-negative bacteria was investigated with a pBR322-pAM beta 1 chimeric plasmid, designated pAT191. This shuttle vector, which possesses the tra functions of the streptococcal plasmid pAM beta 1, was conjugatively transferred from Enterococcus faecalis to Escherichia coli with an average frequency of 5 x 10(-9) per donor colony formed after mating.

  14. A search for new mechanisms to inhibit plasmid conjugation

    OpenAIRE

    Getino Redondo, María

    2011-01-01

    Infections due to antibiotic-resistant (AbR) bacteria are a major cause of morbidity and mortality throughout the world. In addition, the number of new antibiotics being developed has plummeted. Although resistance genes can disseminate by any horizontal gene transfer mechanism, the vast majority of reports of bacterial gene transfer in the environment involve conjugation. Our group developed a method for high-throughput analysis of conjugation. This method was used to check for host genes in...

  15. Bacterial Conjugation in the Cytoplasm of Mouse Cells▿

    OpenAIRE

    Lim, Yin Mei; de Groof, Ad J. C.; Bhattacharjee, Mrinal K.; Figurski, David H.; Eric A Schon

    2008-01-01

    Intracellular pathogenic organisms such as salmonellae and shigellae are able to evade the effects of many antibiotics because the drugs are not able to penetrate the plasma membrane. In addition, these bacteria may be able to transfer genes within cells while protected from the action of drugs. The primary mode by which virulence and antibiotic resistance genes are spread is bacterial conjugation. Salmonellae have been shown to be competent for conjugation in the vacuoles of cultured mammali...

  16. Haptens, conjugates and antibodies for the fungicide cyprodinil

    OpenAIRE

    Mercader Badia, Josep Vicent; Abad Fuentes, Antonio; Abad Somovilla, Antonio; Agulló, Consuelo

    2011-01-01

    [EN] The invention relates to haptens, conjugates, labelled derivatives and antibodies for cyprodinil. Likewise, the present invention also relates to the use of cyprodinil conjugates as test antigens or immunogens for obtaining antibodies of said fungicide, and to the use of the labelled derivatives of cyprodinil as test antigens. Furthermore, the present invention also relates to a method for analysing cyprodinil using the thus obtained antibodies, at times together with the test antigens, ...

  17. Measurement of the charge asymmetry in semileptonic Bs decays

    CERN Document Server

    Abazov, V M; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguiló, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Askew, A; Assis-Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Bargassa, P; Baringer, P; Barnes, C; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benítez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Binder, M; Biscarat, C; Blackler, I; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boline, D; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Burdin, S; Burke, S; Burnett, T H; Busato, E; Buszello, C P; Butler, J M; Böhnlein, A; Bühler, M; Büscher, V; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Claes, D; Clement, B; Clément, C; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M C; Cox, B; Crepe-Renaudin, S; Cutts, D; Cwiok, M; Da Motta, H; Das, A; Das, M; Davies, B; Davies, G; De Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; De, K; Degenhardt, J D; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Doidge, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Déliot, F; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Feligioni, L; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; García, C; García-Bellido, A; Gavrilov, V; Gay, A; Gay, P; Geist, W; Gelhaus, R; Gelé, D; Gerber, C E; Gershtein, Yu; Gillberg, D; Ginther, G; Gollub, N; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, P; Grivaz, J F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutíerrez, G; Gutíerrez, P; Gómez, B; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Holubyev, K; Hong, S J; Hooper, R; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jenkins, A; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J M; Kalk, J R; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A I; Kharzheev, Yu M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Klima, B; Kohli, J M; Konrath, J P; Kopal, M; Korablev, V M; Kotcher, J; Kothari, B; Koubarovsky, A; Kozelov, A V; Krop, D; Kryemadhi, A; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Käfer, D; Kühl, T; Lam, D; Lammers, S; Landsberg, G L; Lazoflores, J; Le Bihan, A C; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lesne, V; Lewis, P; Li, J; Li, L; Li, Q Z; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Z; Lobo, L; Lobodenko, A; Lokajícek, M; Lounis, A; Love, P; Lubatti, H J; Lynker, M; Lyon, A L; Lévêque, J; Maciel, A K A; Madaras, R J; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Michaut, M; Miettinen, H; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Monk, J; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Mättig, P; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nomerotski, A; Novaes, S F; Nunnemann, T; Nöding, C; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Oguri, V; Oliveira, N; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Oteroy-Garzon, G J; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Perea, P M; Peters, K; Peters, Y; Petroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M E; Pompos, A; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S D; Qian, J; Quadt, A; Quinn, B; Rangel, M S; Rani, K J; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F K; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Wang, M H L; Sajot, G; Sanders, M P; Santoro, A F S; Savage, G; Sawyer, L; Scanlon, T; Schaile, A D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sen-Gupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Shpakov, D; Siccardi, V; Sidwell, R A; Simák, V; Sirotenko, V I; Skubic, P L; Slattery, P F; Smith, R P; Snow, G R; Snow, J; Snyder, S; Song, X; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Strom, D; Strovink, M; Ströhmer, R; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Sánchez-Hernández, A; Söldner-Rembold, S; Talby, M; Tamburello, P; Taylor, W; Telford, P; Temple, J; Tiller, B; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Trefzger, T; Trincaz-Duvoid, S; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; Van Kooten, R; Van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A H; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Séguier, F; Vint, P; Vlimant, J R; Von Törne, E; Voutilainen, M; Vreeswijk, M; Wahl, H D; Wang, L; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Weerts, H; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Womersley, J; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, C; Yu, J; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G; de Jong, P; van Eijk, B; vanden Berg, P J; Åsman, B; al, et

    2007-01-01

    We have performed the first direct measurement of the time integrated flavor untagged charge asymmetry in semileptonic Bs decays, Asl(unt), by comparing the decay rate of Bs --> mu+ Ds- nu X, where Ds- --> phi pi- and phi --> K+K-, with the charge-conjugate Bs-bar decay rate. This sample was selected from 1.3/fb of data collected by the D0 experiment in RunII of the Fermilab Tevatron collider. We obtain Asl(unt) = [1.23 +- 0.97(stat) +- 0.17(syst)]*10^-2. Assuming that Delta(M_s)/Gamma_s >> 1 and Delta(Gamma_s)/(2 Gamma_s) < 1, this result can be translated into a measurement on the CP-violating phase in Bs mixing: Delta(Gamma_s)/Delta(M_s)*tan(phi_s) = [2.45 +- 1.93(stat) +- 0.35(syst)]*10^-2.

  18. Efficient polymer solar cells employing a non-conjugated small-molecule electrolyte

    Science.gov (United States)

    Ouyang, Xinhua; Peng, Ruixiang; Ai, Ling; Zhang, Xingye; Ge, Ziyi

    2015-08-01

    Polymer solar cells have drawn a great deal of attention due to the attractiveness of their use in renewable energy sources that are potentially lightweight and low in cost. Recently, numerous significant research efforts have resulted in polymer solar cells with power conversion efficiencies in excess of 9% (ref. 1). Nevertheless, further improvements in performance are sought for commercial applications. Here, we report polymer solar cells with a power conversion efficiency of 10.02% that employ a non-conjugated small-molecule electrolyte as an interlayer. The material offers good contact for photogenerated charge carrier collection and allows optimum photon harvesting in the device. Furthermore, the enhanced performance is attributed to improved electron mobility, enhanced active-layer absorption and properly active-layer microstructures with optimal horizontal phase separation and vertical phase gradation. Our discovery opens a new avenue for single-junction devices by fully exploiting the potential of various material systems with efficiency over 10%.

  19. Multichannel conductance of folded single-molecule wires aided by through-space conjugation.

    Science.gov (United States)

    Chen, Long; Wang, Ya-Hao; He, Bairong; Nie, Han; Hu, Rongrong; Huang, Fei; Qin, Anjun; Zhou, Xiao-Shun; Zhao, Zujin; Tang, Ben Zhong

    2015-03-27

    Deciphering charge transport through multichannel pathways in single-molecule junctions is of high importance to construct nanoscale electronic devices and deepen insight into biological redox processes. Herein, we report two tailor-made folded single-molecule wires featuring intramolecular π-π stacking interactions. The scanning tunneling microscope (STM) based break-junction technique and theoretical calculations show that through-bond and through-space conjugations are integrated into one single-molecule wire, allowing for two simultaneous conducting channels in a single-molecule junction. These folded molecules with stable π-π stacking interaction offer conceptual advances in single-molecule multichannel conductance, and are perfect models for conductance studies in biological systems, organic thin films, and π-stacked columnar aggregates. PMID:25694026

  20. Photoisomerization selectivity in conjugated π-bond systems through local microenvironment

    Science.gov (United States)

    Virshup, Aaron; Martinez, Todd

    2007-03-01

    Photoisomerization represents one of the simplest means to convert light energy into mechanical motion on the molecular scale. Theoretical models of photobiology often require description of not only a small photochemically active chromophore, but also the effects of the much larger solvent or protein environment containing the chromophore. We have recently developed a program for carrying out excited state QM/MM studies of photodynamics using ab initio quantum chemistry techniques for the QM region, and modeling the time evolution of the system with the Full Multiple Spawning method for molecular dynamics. With this method, we show how local charge environments can be used to manipulate and enhance the photoisomer selectivity of small conjugated molecules.

  1. Poly(amidoamine-Cholesterol Conjugate Nanoparticles Obtained by Electrospraying as Novel Tamoxifen Delivery System

    Directory of Open Access Journals (Sweden)

    R. Cavalli

    2011-01-01

    Full Text Available A new poly(amidoamine-cholesterol (PAA-cholesterol conjugate was synthesized, characterized and used to produce nanoparticles by the electrospraying technique. The electrospraying is a method of liquid atomization that consists in the dispersion of a solution into small charged droplets by an electric field. Tuning the electrospraying process parameters spherical PAA-chol nanoparticles formed. The PAA-cholesterol nanoparticles showed sizes lower than 500 nm and spherical shape. The drug incorporation capacity was investigated using tamoxifen, a lipophilic anticancer drug, as model drug. The incorporation of the tamoxifen did not affect the shape and sizes of nanoparticles showing a drug loading of 40%. Tamoxifen-loaded nanoparticles exhibited a higher dose-dependent cytotoxicity than free tamoxifen, while blank nanoparticles did not show any cytotoxic effect at the same concentrations. The electrospray technique might be proposed to produce tamoxifen-loaded PAA-chol nanoparticle in powder form without any excipient in a single step.

  2. Protein carriers of conjugate vaccines: characteristics, development, and clinical trials.

    Science.gov (United States)

    Pichichero, Michael E

    2013-12-01

    The immunogenicity of polysaccharides as human vaccines was enhanced by coupling to protein carriers. Conjugation transformed the T cell-independent polysaccharide vaccines of the past to T cell-dependent antigenic vaccines that were much more immunogenic and launched a renaissance in vaccinology. This review discusses the conjugate vaccines for prevention of infections caused by Hemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis. Specifically, the characteristics of the proteins used in the construction of the vaccines including CRM, tetanus toxoid, diphtheria toxoid, Neisseria meningitidis outer membrane complex, and Hemophilus influenzae protein D are discussed. The studies that established differences among and key features of conjugate vaccines including immunologic memory induction, reduction of nasopharyngeal colonization and herd immunity, and antibody avidity and avidity maturation are presented. Studies of dose, schedule, response to boosters, of single protein carriers with single and multiple polysaccharides, of multiple protein carriers with multiple polysaccharides and conjugate vaccines administered concurrently with other vaccines are discussed along with undesirable consequences of conjugate vaccines. The clear benefits of conjugate vaccines in improving the protective responses of the immature immune systems of young infants and the senescent immune systems of the elderly have been made clear and opened the way to development of additional vaccines using this technology for future vaccine products. PMID:23955057

  3. Identification of host genes that affect acquisition of an integrative and conjugative element in Bacillus subtilis

    OpenAIRE

    Johnson, Christopher M; Grossman, Alan D.

    2014-01-01

    Conjugation, a major type of horizontal gene transfer in bacteria, involves transfer of DNA from a donor to a recipient using donor-encoded conjugation machinery. Using a high throughput screen (Tn-seq), we identified genes in recipients that contribute to acquisition of the integrative and conjugative element ICEBs1 by Bacillus subtilis. We found that null mutations in some genes caused an increase, and others a decrease in conjugation efficiency. Some mutations affected conjugation only whe...

  4. The Bacillus subtilis conjugative transposon ICEBs1 mobilizes plasmids lacking dedicated mobilization functions

    OpenAIRE

    Lee, Catherine A.; Thomas, Jacob; Grossman, Alan D.

    2012-01-01

    Integrative and conjugative elements (ICEs, also known as conjugative transposons) are mobile elements that are found integrated in a host genome and can excise and transfer to recipient cells via conjugation. ICEs and conjugative plasmids are found in many bacteria and are important agents of horizontal gene transfer and microbial evolution. Conjugative elements are capable of self-transfer and also capable of mobilizing other DNA elements that are not able to self-transfer. Plasmids that ca...

  5. Highly Charged Ion Sources

    International Nuclear Information System (INIS)

    In this work a study is made for the factors affecting the production and extraction of highly charged ion beams. Discussion is made for the production of highly charged ions from: the conventional vacuum are ion sources (Pinning PIG and Duoplasmatron DP) and the recent trends type which are (Electron Beam Ion Sources EBIS, Electron Cyclotron Resonance Ion Sources ECRIS and Laser Ion source LIS). The highly charged ions with charge state +7 , O+8 ,Ne+10 , Ar+18 have been extracted from the ECRIS while fully stripped Xe+54 has been extracted from EBIS. Improving the capabilities of the conventional RF ion source to produce multiply charged ions is achieved through the use of electron injection into the plasma or with the use of RF driven ion source. The later is based on coupling the RF power to the discharge through an internal antenna in vacuum are ion source. The argon ion species extracted from these upgraded RF ion sources could reach Ar+5

  6. Selective esterification of non-conjugated carboxylic acids in the presence of conjugated or aromatic carboxylic acids over active carbon supported methanesulfonic acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Non-conjugated carboxylic acids are selectively esterified in good yields in the presence of conjugated or aromatic carboxylic acids by stirring over active carbon supported methanesulfonic acid in di-chloromethane at room temperature.

  7. Self-assembled ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates for targeted gene delivery.

    Science.gov (United States)

    Liang, Kun; Bae, Ki Hyun; Lee, Fan; Xu, Keming; Chung, Joo Eun; Gao, Shu Jun; Kurisawa, Motoichi

    2016-03-28

    Nanosized polyelectrolyte complexes are attractive delivery vehicles for the transfer of therapeutic genes to diseased cells. Here we report the application of self-assembled ternary complexes constructed with plasmid DNA, branched polyethylenimine and hyaluronic acid-green tea catechin conjugates for targeted gene delivery. These conjugates not only stabilize plasmid DNA/polyethylenimine complexes via the strong DNA-binding affinity of green tea catechin, but also facilitate their transport into CD44-overexpressing cells via receptor-mediated endocytosis. The hydrodynamic size, surface charge and physical stability of the complexes are characterized. We demonstrate that the stabilized ternary complexes display enhanced resistance to nuclease attack and polyanion-induced dissociation. Moreover, the ternary complexes can efficiently transfect the difficult-to-transfect HCT-116 colon cancer cell line even in serum-supplemented media due to their enhanced stability and CD44-targeting ability. Confocal microscopic analysis demonstrates that the stabilized ternary complexes are able to promote the nuclear transport of plasmid DNA more effectively than binary complexes and hyaluronic acid-coated ternary complexes. The present study suggests that the ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates can be widely utilized for CD44-targeted delivery of nucleic acid-based therapeutics. PMID:26855049

  8. P-V criticality of charged AdS black holes

    OpenAIRE

    Kubiznak, David; Robert B. Mann

    2012-01-01

    Treating the cosmological constant as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume, we reconsider the critical behaviour of charged AdS black holes. We complete the analogy of this system with the liquid-gas system and study its critical point, which occurs at the point of divergence of specific heat at constant pressure. We calculate the critical exponents and show that they coincide with those of the Van der Waals system.

  9. Space charge dominated beams

    International Nuclear Information System (INIS)

    After an introductory section on the relationship between emittance and beam Coulomb energy we discuss the properties of space charge dominated beams in progressive steps: from uniformly charged bunched beams to non-uniformly charged beams to correlation effects between particles (simulation beams or 'crystalline' beams). A practical application can be found in the beam dynamics of a high-current injector. The concept of correlation energy is of practical interest in computer simulation of high-brilliance beams, where one deals with an artificially enhanced two-particle Coulomb energy, if many real particles are combined into one simulation super-particle. This can be a source of non-physical emittance growth. (orig./HSI)

  10. Controlling molecular ordering in solution-state conjugated polymers

    Science.gov (United States)

    Zhu, J.; Han, Y.; Kumar, R.; He, Y.; Hong, K.; Bonnesen, P. V.; Sumpter, B. G.; Smith, S. C.; Smith, G. S.; Ivanov, I. N.; Do, C.

    2015-09-01

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering

  11. Sources for charged particles

    International Nuclear Information System (INIS)

    This document is a basic course on charged particle sources for post-graduate students and thematic schools on large facilities and accelerator physics. A simple but precise description of the creation and the emission of charged particles is presented. This course relies on every year upgraded reference documents. Following relevant topics are considered: electronic emission processes, technological and practical considerations on electron guns, positron sources, production of neutral atoms, ionization, plasma and discharge, different types of positive and negative ion sources, polarized particle sources, materials for the construction of ion sources, low energy beam production and transport. (N.T.)

  12. Charged conformal Killing spinors

    International Nuclear Information System (INIS)

    We study the twistor equation on pseudo-Riemannian Spinc-manifolds whose solutions we call charged conformal Killing spinors (CCKSs). We derive several integrability conditions for the existence of CCKS and study their relations to spinor bilinears. A construction principle for Lorentzian manifolds admitting CCKS with nontrivial charge starting from CR-geometry is presented. We obtain a partial classification result in the Lorentzian case under the additional assumption that the associated Dirac current is normal conformal and complete the classification of manifolds admitting CCKS in all dimensions and signatures ≤5 which has recently been initiated in the study of supersymmetric field theories on curved space

  13. Preparation of self-assembled core-shell nano structure of conjugated generation 4.5 poly (amidoamine) dendrimer and monoclonal Anti-IL-6 antibody as bioimaging probe.

    Science.gov (United States)

    Mekuria, Shewaye Lakew; Tsai, Hsieh-Chih

    2015-11-01

    In this article, interleukin-6 (IL-6)-conjugated anionic generation 4.5 (G4.5) poly(amidoamine) (PAMAM) was synthesized through EDC/NHS coupling chemistry and evaluated for its optical properties in vitro. Conjugation was confirmed using Fourier-transformed infrared spectroscopy (FT-IR) and 2-dimensional nuclear magnetic resonance (2D NMR). After IL-6 conjugation, nanoparticle size increased to approximately 70 nm and zeta potential increased from -56.5 ± 0.2 to -19.1 ± 2.4 mV due to neutralization of negatively charged G4.5. Wide-angle X-ray scattering (WAXS) suggested that a layered nanoparticle structure was formed by the G4.5/IL-6 conjugate. Most interestingly, the intrinsic fluorescence of G4.5 significantly increased after IL-6 conjugation and underwent a blue shift as a result of H-aggregation. Furthermore, the cellular uptake of the conjugates by HeLa cells was significantly enhanced in comparison to free G4.5, as demonstrated by confocal microscopy and flow cytometry. These results indicated that the described system may be a potential bioimaging probe in vitro. PMID:26263213

  14. Charge configurations in viral proteins.

    OpenAIRE

    Karlin, S; Brendel, V

    1988-01-01

    The spatial distribution of the charged residues of a protein is of interest with respect to potential electrostatic interactions. We have examined the proteins of a large number of representative eukaryotic and prokaryotic viruses for the occurrence of significant clusters, runs, and periodic patterns of charge. Clusters and runs of positive charge are prominent in many capsid and core proteins, whereas surface (glyco)proteins frequently contain a negative charge cluster. Significant charge ...

  15. Recent Advances in Conjugated Polymers for Light Emitting Devices

    Directory of Open Access Journals (Sweden)

    Mohan Raja

    2011-03-01

    Full Text Available A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review.

  16. Recent advances in conjugated polymers for light emitting devices.

    Science.gov (United States)

    Alsalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

    2011-01-01

    A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. PMID:21673938

  17. Charged particle beams

    CERN Document Server

    Humphries, Stanley

    2013-01-01

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

  18. Charged Particle Optics Theory

    Czech Academy of Sciences Publication Activity Database

    Hawkes, P. W.; Lencová, Bohumila

    -, č. 6 (2006), s. 6-8 Grant ostatní: EC 5RP(XE) G5RD-CT-2000-00344 Institutional research plan: CEZ:AV0Z20650511 Keywords : optics of charged particles * design of ion lithography system * spot profile * the finite element method Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering www.phantomsnet.net

  19. Stability of charged membranes

    OpenAIRE

    Bensimon, D; David, F.; Leibler, S.; Pumir, A.

    1990-01-01

    The electrostatic contribution to the bending elastic modulus of charged phospholipid bilayers in an ionic solution is computed. It is found to be the same for conducting and non-conducting membranes and is always stabilizing. This stability for free membranes is shown to be a simple consequence of the vanishing of the physical surface tension.

  20. New heparin–indomethacin conjugate with an ester linkage: Synthesis, self aggregation and drug delivery behavior

    International Nuclear Information System (INIS)

    New heparin–indomethacin conjugate with an ester linkage was prepared by the carbodiimide-mediated condensation reaction, and then characterized by FTIR and 1HNMR analyses. Due to its amphiphilic character, such a conjugate could self-aggregate into spherical nanoparticles in aqueous system, as confirmed by fluorescence spectroscopy, dynamic light scattering and transmission electron microscopy. By the in vitro drug release tests, the resultant conjugate nanoparticles were found to have a sustained and esterase-sensitive release behavior for conjugated indomethacin. In addition, the uptake of these conjugate nanoparticles into human nasopharyngeal carcinoma CNE1 cells was confirmed by fluorescence microscopy. - Highlights: • New heparin–indomethacin conjugate with an ester linkage was prepared. • Such a conjugate could self-aggregate into spherical nanoparticles in aqueous system. • The resultant conjugate nanoparticles exhibited an esterase-sensitive drug release behavior. • The resultant conjugate nanoparticles showed the cellular uptake ability in CNE1 cells

  1. Spontaneous Emission of Charged Bosons from Supercritical Point Charges

    CERN Document Server

    Kim, Sang Pyo

    2013-01-01

    We study the spontaneous emission of charged bosons from supercritical Coulomb potentials and charged black holes. We find the exact emission rate from the Bogoliubov transformation by applying the tunneling boundary condition on the Jost functions at the asymptotic boundaries. The emission rate for charged bosons in the supercritical Coulomb potential increases as the charge $Z\\alpha > 1/2$ of the superatom and the energy of the bosons increase but is suppressed for large angular momenta. We discuss physical implications of the emission of charged bosons from superatoms and charged black holes.

  2. Decay of electric charge on corona charged polyethylene

    International Nuclear Information System (INIS)

    In this paper, the surface potential decay of corona-charged low density polyethylene (LDPE) films has been investigated. It has been found that for the same sample thickness the faster decay occurs in the sample with a higher charging voltage. For the same charging voltage, the surface potential in the thinner sample shows rapid decay. Our new evidence from both the surface potential measurement on multilayer samples and space charge measurement suggests the surface potential decay is a bulk limited process. More importantly, space charge measurement indicates double injection has taken place during corona charging process.

  3. Charge injection and transport in fluorene-based copolymers.

    Science.gov (United States)

    Fong, Hon Hang; Malliaras, George G.; Lu, Tianjian; Dunlap, David

    2007-03-01

    Fluorene-based copolymer is considered to be one of the most promising hole transporting and blue light-emitting conjugated polymers used in polymeric light-emitting diodes (PLEDs). Time-of-flight (TOF) technique has been employed to evaluate the charge drift mobility under a temperature range between 200 - 400 K at the thick film regime (1-10 micron). Meanwhile, contact ohmicity is studied by Dark Current Space Charge Limited Conduction (DISCLC) technique. Charge injection efficiencies from different electrical contacts are also studied and the corresponding injection barriers are independently investigated by photoemission and electroabsorption spectroscopies. Results show that the copolymers exhibit non-dispersive charge transport behavior and possess superior mobilities of up to 0.01cm^2V-1s-1 while single-carrier devices from various electrical contacts such as PEDOT:PSS are varied, depending on the chemical structure of amine component in the fluorene-triarylamine copolymers. Results will shed light on the enhancement of device efficiency and stability in the future polymer electronic devices.

  4. Synthesis and characterization of new low-molecular-weight lysine-conjugated Gd-DTPA contrast agents.

    Science.gov (United States)

    Laurent, Sophie; Burtea, Carmen; Vander Elst, Luce; Muller, Robert N

    2011-01-01

    Various blood pool contrast agents (CAs), characterized by intravascular distribution, have been developed to assist contrast enhanced magnetic resonance angiography (MRA). Among these CAs, the DTPA derivatives conjugated to synthetic polypeptides, such as polylysine, represent attractive candidates for blood pool imaging. However, due to the presence of charged residues located on their backbone, these agents are retained in the kidneys and this compromises their long blood half-life. In order to overcome this major drawback of the polylysine compounds, two new low-molecular-weight CAs were synthesized in the present work by conjugating four or six 1-p-isothiocyanatobenzyl-DTPA moieties to tri- or penta-Lys peptides [(Gd-DTPA)(4) Lys(3) and (Gd-DTPA)(6) Lys(5)], respectively. All the -NH(2) groups of Lys were thus blocked by covalent conjugation to DTPA. The stability and relaxometric properties of these compounds, as well as their pharmacokinetic and biodistribution characteristics, were then evaluated. The half-life in blood of these new polylysine derivatives, as determined in rats, is twofold longer than that of Gd-DTPA. The compounds could thus be optimal blood pool markers for MRA, which typically uses fast acquisition times. The absence of positive molecular charge did not limit their retention in kidneys 2 h after administration. On the other hand, (Gd-DTPA)(4) Lys(3) is retained in kidneys to a lesser extent than (Gd-DTPA)(6) Lys(5) . Their moderate retention in blood and their higher stability and relaxivity in comparison with Gd-DTPA highlight these polylysine derivatives as optimal compared with previously developed polylysine compounds. PMID:21861283

  5. The Preparation and Characterization of Conjugated Linolenic Acid

    Institute of Scientific and Technical Information of China (English)

    Cao Ying; Yang Lin; Chen Zhen-Yu

    2004-01-01

    Conjugated Linolenic Acid (CLN) has recently been shown to have a more strong cytotoxic effect on various human tumor cell lines than CLA. In CLN, all the three double bonds are conjugated, whereas they are methylene-interrupted in LN. Some seed oil, such as tung oil and pomegranate seed oil, principally consist of CLN, accounting for 76.5% and 75.5%, respectively.CLN can be characterized using the combination of gas chromatography (GC), highperformance liquid chromatography (HPLC) and UV /VIS spectrophotomea-ic analysis. GC can separate the CLN from other fatty acids and HPLC can separate the individual CLN isomers.The conjugated triene formation has a maximum absorbency at 268 nm and the conjugated diene formation has an absorbency at 235 nm in UV spectrum.CLN was prepared from linseed oil by isomerization reaction in our present study. By treating at was isomerized and the product was purified by recrystallizing in the methanol. The GC and UV /VIS spectrophotometric analysis were used to characterize the obtained products. It was found that the a-LN in the linseed oil was converted to the corresponding conjugated diene acids and CLN. The GC analysis also showed that there formed about 20% CLN when reacting for 10h with 40% KOH/ethylene glycol.

  6. Antibody-radioisotope conjugates for tumor localization and treatment

    International Nuclear Information System (INIS)

    In principle, anti-tumor antibodies can be used to carry radioactivity to tumors for in-vivo diagnosis and treatment of cancer. First, for diagnostic purposes, an antibody that targets a specific antigen (for example, the p97 antigen of human melanoma tumor), is labeled with a tracer amount of radioactivity. When this antibody-radioisotope conjugate is injected into the blood stream, the antibody carries the radioactivity throughout the body and in time, percolates through all the tissues of the body. Because the tumor has specific antigens to which the antibody can bind, the antibody conjugate progressively accumulates in the tumor. Using conventional nuclear medicine imaging equipment, the body of the patient is scanned for radioactivity content, and a map of the distribution of the radioactivity is displayed on photographic film. The tumor shows up as a dense area of radio-activity. These same antibody-radioisotope conjugates may be used for therapy of tumors, except that in this case large amounts of radioactivity are loaded on the antibody. After localization of the conjugate there is sufficient radiation deposited in the tumor of radiotherapy. The success of this approach in the clinic is determined in large measure by the concentration gradient that can be achieved between tissue antibody conjugate in tumor versus normal tissue

  7. A novel chemistry for conjugating pneumococcal polysaccharides to Luminex microspheres.

    Science.gov (United States)

    Schlottmann, Sonela A; Jain, Neil; Chirmule, Narendra; Esser, Mark T

    2006-02-20

    Here we describe a novel method to conjugate pneumococcal polysaccharides (PnPS) to Luminex microspheres for use in serological assays. 4-(4,6-dimethoxy[1,3,5]triazin-2-yl)-4-methyl-morpholinium (DMTMM) modification of PnPS and conjugation to carboxyl functional groups on Luminex microspheres (COOH-DMTMM method) was shown to be a reproducible chemistry that efficiently conjugated PnPS to Luminex microspheres without affecting the antigenicity of a broad set of PnPS. The COOH-DMTMM method was compared to three other methods for robustness, reproducibility and effect on PnPS antigenicity in a multiplexed assay format. The other methods examined included adsorption of the unmodified PnPS to Luminex microspheres, oxidation of the PnPS to conjugate them to amino-modified microspheres using carbodiimide chemistry and poly-l-lysine modification of the PnPS before conjugating to carboxy Luminex microspheres using carbodiimide chemistry. Of the four methods, the COOH-DMTMM chemistry was shown to be a robust methodology, producing stable PnPS coupled microspheres with a 4-log dynamic range and low cross-reactivity when used in a PnPS-specific IgG serology assay. This novel chemistry should be useful for developing serological assays to measure antibodies to polysaccharides for use in vaccine and epidemiology studies. PMID:16448665

  8. Optimization of BEV Charging Strategy

    Science.gov (United States)

    Ji, Wei

    This paper presents different approaches to optimize fast charging and workplace charging strategy of battery electric vehicle (BEV) drivers. For the fast charging analysis, a rule-based model was built to simulate BEV charging behavior. Monte Carlo analysis was performed to explore to the potential range of congestion at fast charging stations which could be more than four hours at the most crowded stations. Genetic algorithm was performed to explore the theoretical minimum waiting time at fast charging stations, and it can decrease the waiting time at the most crowded stations to be shorter than one hour. A deterministic approach was proposed as a feasible suggestion that people should consider to take fast charging when the state of charge is approaching 40 miles. This suggestion is hoped to help to minimize potential congestion at fast charging stations. For the workplace charging analysis, scenario analysis was performed to simulate temporal distribution of charging demand under different workplace charging strategies. It was found that if BEV drivers charge as much as possible and as late as possible at workplace, it could increase the utility of solar-generated electricity while relieve grid stress of extra intensive electricity demand at night caused by charging electric vehicles at home.

  9. Conjugated Linoleic Triacylglycerols Exhibit Superior Lymphatic Absorption Than Free Conjugate Linoleic Acids and Have Antiobesity Properties.

    Science.gov (United States)

    Woo, Hyunjoon; Chung, Min-Yu; Kim, Juyeon; Kong, Daecheol; Min, Jinyoung; Choi, Hee-Don; Choi, In-Wook; Kim, In-Hwan; Noh, Sang K; Kim, Byung Hee

    2016-05-01

    This study aimed to compare lymphatic absorption of conjugated linoleic acids (CLAs) in the triacylglycerol (TAG) or free fatty acid (FFA) form and to examine the antiobesity effects of different doses of CLAs in the TAG form in animals. Conjugated linoleic TAGs (containing 70.3 wt% CLAs; CLA-TAG) were prepared through lipase-catalyzed esterification of glycerol with commercial CLA mixtures (CLA-FFA). Lymphatic absorption of CLA-TAG and CLA-FFA was compared in a rat model of lymphatic cannulation. Greater amounts of cis-9,trans-11 and trans-10,cis-12 CLAs were detected in the collected lymph from a lipid emulsion containing CLA-TAG. This result suggests that CLA-TAG has greater capacity for lymphatic absorption than does CLA-FFA. The antiobesity efficacy of CLA-TAG at different doses was examined in mice with diet-induced obesity. A high-fat diet (HFD) for 12 weeks caused a significant increase in body weight and epididymal and retroperitoneal fat weights, which were significantly decreased by 2% dietary supplementation (w/w) with CLA-TAG. CLA-TAG at 2% significantly attenuated the HFD-induced upregulation of serum TAG, but led to hepatomegaly and exacerbated HFD-induced hypercholesterolemia. CLA-TAG at 1% significantly attenuated upregulation of retroperitoneal fat weight and significantly increased liver weight, which was decreased by the HFD. Nonetheless, the liver weight in group "HFD +1% CLA-TAG" was not significantly different from that of normal diet controls. CLA-TAG at 1% significantly reduced serum TAG levels and did not exacerbate HFD-induced hypercholesterolemia. Thus, 1% dietary supplementation with CLA-TAG reduces retroperitoneal fat weight without apparent hepatomegaly, a known side-effect of CLAs in mouse models of obesity. PMID:27081749

  10. Charge Breeding of Radioactive Ions

    OpenAIRE

    Wenander, F. J. C.

    2014-01-01

    Charge breeding is a technique to increase the charge state of ions, in many cases radioactive ions. The singly charged radioactive ions, produced in an isotope separator on-line facility, and extracted with a low kinetic energy of some tens of keV, are injected into a charge breeder, where the charge state is increased to Q. The transformed ions are either directed towards a dedicated experiment requiring highly charged ions, or post-accelerated to higher beam energies. In this paper the phy...

  11. Recent advances in the construction of antibody-drug conjugates

    Science.gov (United States)

    Chudasama, Vijay; Maruani, Antoine; Caddick, Stephen

    2016-02-01

    Antibody-drug conjugates (ADCs) comprise antibodies covalently attached to highly potent drugs using a variety of conjugation technologies. As therapeutics, they combine the exquisite specificity of antibodies, enabling discrimination between healthy and diseased tissue, with the cell-killing ability of cytotoxic drugs. This powerful and exciting class of targeted therapy has shown considerable promise in the treatment of various cancers with two US Food and Drug Administration approved ADCs currently on the market (Adcetris and Kadcyla) and approximately 40 currently undergoing clinical evaluation. However, most of these ADCs exist as heterogeneous mixtures, which can result in a narrow therapeutic window and have major pharmacokinetic implications. In order for ADCs to deliver their full potential, sophisticated site-specific conjugation technologies to connect the drug to the antibody are vital. This Perspective discusses the strategies currently used for the site-specific construction of ADCs and appraises their merits and disadvantages.

  12. Synthesis and Spectral Studies of CdTe–Dendrimer Conjugates

    Directory of Open Access Journals (Sweden)

    Ghosh Srabanti

    2009-01-01

    Full Text Available Abstract In order to couple high cellular uptake and target specificity of dendrimer molecule with excellent optical properties of semiconductor nanoparticles, the interaction of cysteine-capped CdTe quantum dots with dendrimer was investigated through spectroscopic techniques. NH2-terminated dendrimer molecule quenched the photoluminescence of CdTe quantum dots. The binding constants and binding capacity were calculated, and the nature of binding was found to be noncovalent. Significant decrease in luminescence intensity of CdTe quantum dots owing to noncovalent binding with dendrimer limits further utilization of these nanoassemblies. Hence, an attempt is made, for the first time, to synthesize stable, highly luminescent, covalently linked CdTe–Dendrimer conjugate in aqueous medium using glutaric dialdehyde (G linker. Conjugate has been characterized through Fourier transform infrared spectroscopy and transmission electron microscopy. In this strategy, photoluminescence quantum efficiency of CdTe quantum dots with narrow emission bandwidths remained unaffected after formation of the conjugate.

  13. Click Functionalization of a Dibenzocyclooctyne-Containing Conjugated Polyimine.

    Science.gov (United States)

    Kardelis, Vladimir; Chadwick, Ryan C; Adronov, Alex

    2016-01-18

    A conjugated poly(phenyl-co-dibenzocyclooctyne) Schiff-base polymer, prepared through polycondensation of dibenzocyclooctyne bisamine (DIBO-(NH2)2) with bis(hexadecyloxy)phenyldialdehyde, is reported. The resulting polymer, which has a high molecular weight (M(n)>30 kDa, M(w)>60 kDa), undergoes efficient strain-promoted alkyne-azide cycloaddition reactions with a series of azides. This enables quantitative modification of each repeat unit within the polymer backbone and the rapid synthesis of a conjugated polymer library with widely different substituents but a consistent degree of polymerization (DP). Kinetic studies show a second-order reaction rate constant that is consistent with monomeric dibenzocyclooctynes. Grafting with azide-terminated polystyrene and polyethylene glycol monomethyl ether chains of varying molecular weight resulted in the efficient syntheses of a series of graft copolymers with a conjugated backbone and maximal graft density. PMID:26643988

  14. Small angle scattering from protein/sugar conjugates

    Science.gov (United States)

    Jackson, Andrew; White, John

    2006-11-01

    The Maillard reaction between free amine groups on proteins and sugars is well known. We have examined the effect of the reaction of the casein group of milk proteins with sugars on their nanoscale structure and aggregation. The small angle neutron scattering from beta casein and sodium caseinate and their sugar conjugates have been studied as a function of solution concentration. At high conjugate concentration (greater than ca. 5 mg/ml) the addition of sugar reduces supra-micellar aggregation of the protein whilst at lower concentration, where the protein is expected to be deaggregated already, little effect is seen. Guinier analysis of the scattering data show a radius of gyration of around 75 A˚ for beta casein in solution and around 80 A˚ for the sucrose conjugate.

  15. Small angle scattering from protein/sugar conjugates

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Andrew [Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia)]. E-mail: ajj@nist.gov; White, John [Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia)

    2006-11-15

    The Maillard reaction between free amine groups on proteins and sugars is well known. We have examined the effect of the reaction of the casein group of milk proteins with sugars on their nanoscale structure and aggregation. The small angle neutron scattering from beta casein and sodium caseinate and their sugar conjugates have been studied as a function of solution concentration. At high conjugate concentration (greater than ca. 5mg/ml) the addition of sugar reduces supra-micellar aggregation of the protein whilst at lower concentration, where the protein is expected to be deaggregated already, little effect is seen. Guinier analysis of the scattering data show a radius of gyration of around 75A-bar for beta casein in solution and around 80A-bar for the sucrose conjugate.

  16. Streamline upwind finite element method for conjugate heat transfer problems

    Institute of Scientific and Technical Information of China (English)

    Niphon Wansophark; Atipong Malatip; Pramote Dechaumphai; Yunming Chen

    2005-01-01

    This paper presents a combined finite element method for solving conjugate heat transfer problems where heat conduction in a solid is coupled with heat convection in viscous fluid flow. The streamline upwind finite element method is used for the analysis of thermal viscous flow in the fluid region, whereas the analysis of heat conduction in solid region is performed by the Galerkin method. The method uses the three-node triangular element with equal-order interpolation functions for all the variables of the velocity components,the pressure and the temperature. The main advantage of the proposed method is to consistently couple heat transfer along the fluid-solid interface. Three test cases, i.e. conjugate Couette flow problem in parallel plate channel, counter-flow in heat exchanger, and conjugate natural convection in a square cavity with a conducting wall, are selected to evaluate the efficiency of the present method.

  17. Chitosan nanoparticles conjugate with trypsin and trypsin inhibitor.

    Science.gov (United States)

    Chanphai, P; Tajmir-Riahi, H A

    2016-06-25

    Chitosan-protein conjugates are widely used in therapeutic drug delivery. We report the bindings of chitosan nanoparticles with trypsin (try) and trypsin inhibitor (tryi), using thermodynamic analysis and multiple spectroscopic methods. Thermodynamic parameters ΔS, ΔH and ΔG showed chitosan-protein bindings occur mainly via H-bonding and van der Waals contacts with trypsin inhibitor forming more stable conjugate than trypsin. As chitosan size increased more stable polymer-protein conjugate was formed. Chitosan complexation induces more perturbations of trypsin inhibitor structure than trypsin with reduction of protein alpha-helix and major increase of random structure. The negative value of ΔG indicates spontaneous protein-chitosan complexation at room temperature. Chitosan nanoparticles can be used to transport trypsin and trypsin inhibitor. PMID:27083826

  18. Progress towards meningitis prevention in the conjugate vaccines era

    Directory of Open Access Journals (Sweden)

    Cristina Aparecida Borges Laval

    2003-10-01

    Full Text Available Acute bacterial meningitis is an important cause of morbidity and mortality among children less than five years old. Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis are the most important agents of bacterial meningitis in developing countries. The development of the conjugate vaccines in the beginning of the 90's, especially type b H. influenzae (Hib, and more recently the heptavalent pneumococcal and the serogroup C meningococcal vaccines, have contributed directly to changes in the epidemiological profile of these invasive diseases (direct effect and of their carriage status (indirect effect. We review the impact of the Hib conjugate vaccine in Latin American countries, where this vaccine has been implemented, and the potential of pneumococcal and meningococcal conjugate vaccines for the reduction of meningitis worldwide. We also address constraints for the development and delivery of these vaccines and review new candidate state-of-the-art vaccines. The greatest challenge, undoubtedly, is to implement these vaccines worldwide, especially in the developing regions.

  19. Full Eulerian lattice Boltzmann model for conjugate heat transfer.

    Science.gov (United States)

    Hu, Yang; Li, Decai; Shu, Shi; Niu, Xiaodong

    2015-12-01

    In this paper a full Eulerian lattice Boltzmann model is proposed for conjugate heat transfer. A unified governing equation with a source term for the temperature field is derived. By introducing the source term, we prove that the continuity of temperature and its normal flux at the interface is satisfied automatically. The curved interface is assumed to be zigzag lines. All physical quantities are recorded and updated on a Cartesian grid. As a result, any complicated treatment near the interface is avoided, which makes the proposed model suitable to simulate the conjugate heat transfer with complex interfaces efficiently. The present conjugate interface treatment is validated by several steady and unsteady numerical tests, including pure heat conduction, forced convection, and natural convection problems. Both flat and curved interfaces are also involved. The obtained results show good agreement with the analytical and/or finite volume results. PMID:26764851

  20. Small angle scattering from protein/sugar conjugates

    International Nuclear Information System (INIS)

    The Maillard reaction between free amine groups on proteins and sugars is well known. We have examined the effect of the reaction of the casein group of milk proteins with sugars on their nanoscale structure and aggregation. The small angle neutron scattering from beta casein and sodium caseinate and their sugar conjugates have been studied as a function of solution concentration. At high conjugate concentration (greater than ca. 5mg/ml) the addition of sugar reduces supra-micellar aggregation of the protein whilst at lower concentration, where the protein is expected to be deaggregated already, little effect is seen. Guinier analysis of the scattering data show a radius of gyration of around 75A-bar for beta casein in solution and around 80A-bar for the sucrose conjugate

  1. FAST NAS-RIF ALGORITHM USING ITERATIVE CONJUGATE GRADIENT METHOD

    Directory of Open Access Journals (Sweden)

    A.M.Raid

    2014-04-01

    Full Text Available Many improvements on image enhancemen have been achieved by The Non-negativity And Support constraints Recursive Inverse Filtering (NAS-RIF algorithm. The Deterministic constraints such as non negativity, known finite support, and existence of blur invariant edges are given for the true image. NASRIF algorithms iterative and simultaneously estimate the pixels of the true image and the Point Spread Function (PSF based on conjugate gradients method. NAS-RIF algorithm doesn’t assume parametric models for either the image or the blur, so we update the parameters of conjugate gradient method and the objective function for improving the minimization of the cost function and the time for execution. We propose a different version of linear and nonlinear conjugate gradient methods to obtain the better results of image restoration with high PSNR.

  2. Ultrafast photoinduced energy and electron transfer in multi-modular donor-acceptor conjugates.

    Science.gov (United States)

    El-Khouly, Mohamed E; Wijesinghe, Channa A; Nesterov, Vladimir N; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis

    2012-10-22

    New multi-modular donor-acceptor conjugates featuring zinc porphyrin (ZnP), catechol-chelated boron dipyrrin (BDP), triphenylamine (TPA) and fullerene (C(60)), or naphthalenediimide (NDI) have been newly designed and synthesized as photosynthetic antenna and reaction-center mimics. The X-ray structure of triphenylamine-BDP is also reported. The wide-band capturing polyad revealed ultrafast energy-transfer (k(ENT) =1.0 × 10(12) s(-1)) from the singlet excited BDP to the covalently linked ZnP owing to close proximity and favorable orientation of the entities. Introducing either fullerene or naphthalenediimide electron acceptors to the TPA-BDP-ZnP triad through metal-ligand axial coordination resulted in electron donor-acceptor polyads whose structures were revealed by spectroscopic, electrochemical and computational studies. Excitation of the electron donor, zinc porphyrin resulted in rapid electron-transfer to coordinated fullerene or naphthalenediimide yielding charge separated ion-pair species. The measured electron transfer rate constants from femtosecond transient spectral technique in non-polar toluene were in the range of 5.0 × 10(9)-3.5 × 10(10) s(-1). Stabilization of the charge-separated state in these multi-modular donor-acceptor polyads is also observed to certain level. PMID:22996909

  3. Understanding supercapacitors based on nano-hybrid materials with interfacial conjugation

    Institute of Scientific and Technical Information of China (English)

    George Z. Chen

    2013-01-01

    The recent fast development of supercapacitors, also known scientifically as electrochemical capacitors, has benefited significantly from synthesis, characterisations and electrochemistry of nanoma-terials. Herein, the principle of supercapacitors is explained in terms of performance characteristics and charge storage mechanisms, i.e. double layer (or interfacial) capacitance and pseudo-capacitance. The semiconductor band model is applied to qualitatively account for the pseudo-capacitance in association with rectangular cyclic voltammograms (CVs) and linear galvanostatic charging and discharging plots (GCDs), aiming to differentiate supercapacitors from rechargeable batteries. The invalidity of using peak shaped CVs and non-linear GCDs for capacitance measurement is highlighted. A selective review is given to the nano-hybrid materials between carbon nanotubes and redox active materials such as electronically conducting polymers and transition metal oxides. A new concept,“interfacial conjugation”, is introduced to reflect the capacitance enhancement resulting from π-π stacking interactions at the interface between two materials with highly conjugated chemical bonds. The prospects of carbon nanotubes and graphenes for supercapacitor applications are briefly compared and discussed. Hopefully, this article can help readers to understand supercapacitors and nano-hybrid materials so that further developments in materials design and synthesis, and device engineering can be more efficient and objective.

  4. Fourth-rank hypermagnetizability of medium-size planar conjugated molecules and fullerene

    Science.gov (United States)

    Pagola, G. I.; Pelloni, S.; Caputo, M. C.; Ferraro, M. B.; Lazzeretti, P.

    2005-09-01

    The fourth-rank hypermagnetizability tensor of a series of planar conjugated molecules—i.e., aromatic naphthalene, nonaromatic borazine, antiaromatic flattened cyclo-octatetraene, pentalene, indacene, and the 60-carbon fullerene,—has been evaluated at the coupled Hartree-Fock level of accuracy, within the conventional common-origin approach, via extended Gaussian basis sets. The theoretical predictions indicate that antiaromatic molecules are characterized by out-of-plane hypermagnetizability components much bigger than benzene’s. The fullerene cage has a hypermagnetizability exceeding that of planar aromatics by three orders of magnitude. However, the experimental determination of the hypermagnetizabilities constitutes a big challenge. Chemically substituted carbon clusters seem good candidates for detection of cubic magnetic response. Understanding of the calculated hypermagnetizabilities is eased by plots of the differential electron density induced by the applied field. It is found that a strong magnetic field perpendicular to the plane of antiaromatic molecules causes a distortion of the electron charge density, which tends to break C-C double bonds. This charge stretching has a dynamical origin and may be qualitatively explained as a feedback effect due to the Lorentz force acting on the electron current density.

  5. Fourth-rank hypermagnetizability of medium-size planar conjugated molecules and fullerene

    International Nuclear Information System (INIS)

    The fourth-rank hypermagnetizability tensor of a series of planar conjugated molecules--i.e., aromatic naphthalene, nonaromatic borazine, antiaromatic flattened cyclo-octatetraene, pentalene, indacene, and the 60-carbon fullerene,--has been evaluated at the coupled Hartree-Fock level of accuracy, within the conventional common-origin approach, via extended Gaussian basis sets. The theoretical predictions indicate that antiaromatic molecules are characterized by out-of-plane hypermagnetizability components much bigger than benzene's. The fullerene cage has a hypermagnetizability exceeding that of planar aromatics by three orders of magnitude. However, the experimental determination of the hypermagnetizabilities constitutes a big challenge. Chemically substituted carbon clusters seem good candidates for detection of cubic magnetic response. Understanding of the calculated hypermagnetizabilities is eased by plots of the differential electron density induced by the applied field. It is found that a strong magnetic field perpendicular to the plane of antiaromatic molecules causes a distortion of the electron charge density, which tends to break C-C double bonds. This charge stretching has a dynamical origin and may be qualitatively explained as a feedback effect due to the Lorentz force acting on the electron current density

  6. Functionalization of emissive conjugated polymer nanoparticles by coprecipitation: consequences for particle photophysics and colloidal properties

    Science.gov (United States)

    Singh, Amita; Bezuidenhout, Michael; Walsh, Nichola; Beirne, Jason; Felletti, Riccardo; Wang, Suxiao; Fitzgerald, Kathleen T.; Gallagher, William M.; Kiely, Patrick; Redmond, Gareth

    2016-07-01

    The functionalization of polyfluorene (PFO) nanoparticles by coprecipitation of the conjugated polymer with an amphiphilic comb polymer, consisting of a hydrophobic polystyrene backbone with hydrophilic, carboxylic acid-terminated polyethylene oxide side-chains (PS-PEG-COOH), is investigated. The comb polymer affects the properties of the formed hybrid nanoparticles. Non-functionalized particles are typically larger (28 nm) than functionalized ones (20 nm); peak molar extinction coefficients are found to differ in a similar trend. Zeta potentials are negative, consistent with negative surface charge on PFO particles due to chemical defect formation, with additional charge on functionalized particles due to the pendant carboxylic acid groups. Emission quantum yields of functionalized particles are typically larger, consistent with lower efficiency of energy transfer to quenchers in smaller particles and weaker PFO interchain interactions due to chain dilution. The trend in per-particle fluorescence brightness values, as confirmed by single particle fluorescence imaging, reflects the nanoparticle extinction coefficients. Photostability studies on aqueous dispersions of hybrid particles indicate mild photobrightening under continuous illumination while PFO particles exhibit slow exponential emission decay. Functionalized particles are also resistant to aggregation during exposure to adenocarcinoma cells. Generally, the hybrid particles exhibit more favorable time-, pH- and medium-dependent stabilities, likely due to steric and electrostatic stabilization by PEG-carboxylic acid functionalities. Overall, the functionalized particles exhibit attractive properties: Reasonably small size, tight size distribution, high absorption cross section, radiative rate and emission quantum yield, excellent brightness and photostability, and good colloidal stability.

  7. Intelligent battery charging system

    Science.gov (United States)

    Everett, Hobert R., Jr.

    1991-09-01

    The present invention is a battery charging system that provides automatic voltage selection, short circuit protection, and delayed output to prevent arcing or pitting. A second embodiment of the invention provides a homing beacon which transmits a signal so that a battery powered mobile robot may home in on and contact the invention to charge its battery. The invention includes electric terminals isolated from one another. One terminal is grounded and the other has a voltage applied to it through a resistor connected to the output of a DC power supply. A voltage scaler is connected between the resistor and the hot terminal. An On/Off controller and a voltage mode selector sense the voltage provided at the output of the voltage scaler.

  8. High Voltage Charge Pump

    KAUST Repository

    Emira, Ahmed A.

    2014-10-09

    Various embodiments of a high voltage charge pump are described. One embodiment is a charge pump circuit that comprises a plurality of switching stages each including a clock input, a clock input inverse, a clock output, and a clock output inverse. The circuit further comprises a plurality of pumping capacitors, wherein one or more pumping capacitors are coupled to a corresponding switching stage. The circuit also comprises a maximum selection circuit coupled to a last switching stage among the plurality of switching stages, the maximum selection circuit configured to filter noise on the output clock and the output clock inverse of the last switching stage, the maximum selection circuit further configured to generate a DC output voltage based on the output clock and the output clock inverse of the last switching stage.

  9. Hidden Charged Dark Matter

    CERN Document Server

    Feng, Jonathan L; Tu, Huitzu; Yu, Hai-Bo

    2009-01-01

    We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact U(1) gauge symmetry of the hidden sector. Such candidates are predicted in simple WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many potentially disastrous implications for astrophysics: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may destroy its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ~ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially violating constraints from the Bullet Cluster and the observed morphology of galactic halos. We show that all of these constraints are satisfied and are ...

  10. Controlling charge on levitating drops.

    Science.gov (United States)

    Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M

    2007-08-01

    Levitation technologies are used in containerless processing of materials, as microscale manipulators and reactors, and in the study of single drops and particles. Presented here is a method for controlling the amount and polarity of charge on a levitating drop. The method uses single-axis acoustic levitation to trap and levitate a single, initially neutral drop with a diameter between 400 microm and 2 mm. This drop is then charged in a controllable manner using discrete packets of charge in the form of charged drops produced by a piezoelectric drop-on-demand dispenser equipped with a charging electrode. The magnitude of the charge on the dispensed drops can be adjusted by varying the voltage applied to the charging electrode. The polarity of the charge on the added drops can be changed allowing removal of charge from the trapped drop (by neutralization) and polarity reversal. The maximum amount of added charge is limited by repulsion of like charges between the drops in the trap. This charging scheme can aid in micromanipulation and the study of charged drops and particles using levitation. PMID:17580951

  11. Self-Assembled Conjugated Polymer Nanometer Scale Devices

    Institute of Scientific and Technical Information of China (English)

    Wenping Hu; Hiroshi Nakashima; Keiichi Torimitsu; Yunqi Liu; Daoben Zhu

    2005-01-01

    @@ 1Introduction Nanometer scale devices, as the next generation devices of electronics, have got a worldwide attention and rapid development recently. Simultaneously, conjugated polymers have been applied in organic electronics successfully because of their outstanding electronic-photonic properties. However, as far as we know few reports have dealt with the fabrication of nanometer scale devices by using conjugated polymers, although the combination of nanometer scale devices and polymers will not only extend conjugated polymers to Nanoelectronics, but also excavate the behaviors of polymer molecules at nano-molecular level, such as the electron transport through polymer molecules. One reason for this case is due to the lack of rigidity for most polymers.It results in the failure to bridge them between electrodes or to stand on substrates, therefore, fails to be characterized by scanning probe microscopy. Another reason is that the non-functionalized end-group of most polymers is impossible to graft on substrates through chemical bonds. Here, we introduce a self-assembled conjugated polymer can be used to fabricate nanodevices by self-assembly. The conjugated polymer is a derivative of poly(p-phenyleneethynylene)s (PPE) with thioacetyl end groups (Fig. 1). In general, it is known that for self-assembling ideal nanojunctions the materials should possess: a) conductivity, b) rigidity (for wiring and bridging between electrodes), and c) connectivity (for covalent attachment to metallic or semiconductor solid surfaces). PPE provides good conductivity owing to its special π-conjugated configuration. It is also believed that in principle PPE molecules possess rigidity because of the presence of the triple bond in their molecules,which prevents the rotation of adjacent phenyl rings with respect to each other.

  12. High-conjugation-efficiency aqueous CdSe quantum dots.

    Science.gov (United States)

    Au, Giang H T; Shih, Wan Y; Shih, Wei-Heng

    2013-11-12

    Quantum dots (QDs) are photoluminescent nanoparticles that can be directly or indirectly coupled with a receptor such as an antibody to specifically image a target biomolecule such as an antigen. Recent studies have shown that QDs can be directly made at room temperature and in an aqueous environment (AQDs) with 3-mercaptopropionic acid (MPA) as the capping ligand without solvent and ligand exchange typically required by QDs made by the organic solvent routes (OQDs). In this study, we have synthesized CdSe AQDs and compared their conjugation efficiency and imaging efficacy with commercial carboxylated OQDs in HT29 colon cancer cells using a primary antibody-biotinylated secondary antibody-streptavidin (SA) sandwich. We showed that the best imaging condition for AQDs occurred when one AQD was bound with 3 ± 0.3 SA with a nominal SA/AQD ratio of 4 corresponding to an SA conjugation efficiency of 75 ± 7.5%. In comparison, for commercial CdSe-ZnS OQDs to achieve 2.7 ± 0.4 bound SAs per OQD for comparable imaging efficacy a nominal SA/OQD ratio of 80 was needed corresponding to an SA conjugation efficiency of 3.4 ± 0.5% for CdSe-ZnS OQDs. The more than 10 times better SA conjugation efficiency of the CdSe AQDs as compared to that of the CdSe-ZnS OQDs was attributed to more capping molecules on the AQD surface as a result of the direct aqueous synthesis. More capping molecules on the AQD surface also allowed the SA-AQD conjugate to be stable in cell culture medium for more than three days without losing their staining capability in a flowing cell culture medium. In contrast, SA-OQD conjugates aggregated in cell culture medium and in phosphate buffer saline solution over time. PMID:24151632

  13. Novel synthetic (poly)glycerolphosphate-based antistaphylococcal conjugate vaccine.

    Science.gov (United States)

    Chen, Quanyi; Dintaman, Jay; Lees, Andrew; Sen, Goutam; Schwartz, David; Shirtliff, Mark E; Park, Saeyoung; Lee, Jean C; Mond, James J; Snapper, Clifford M

    2013-07-01

    Staphylococcal infections are a major source of global morbidity and mortality. Currently there exists no antistaphylococcal vaccine in clinical use. Previous animal studies suggested a possible role for purified lipoteichoic acid as a vaccine target for eliciting protective IgG to several Gram-positive pathogens. Since the highly conserved (poly)glycerolphosphate backbone of lipoteichoic acid is a major antigenic target of the humoral immune system during staphylococcal infections, we developed a synthetic method for producing glycerol phosphoramidites to create a covalent 10-mer of (poly)glycerolphosphate for potential use in a conjugate vaccine. We initially demonstrated that intact Staphylococcus aureus elicits murine CD4(+) T cell-dependent (poly)glycerolphosphate-specific IgM and IgG responses in vivo. Naive mice immunized with a covalent conjugate of (poly)glycerolphosphate and tetanus toxoid in alum plus CpG-oligodeoxynucleotides produced high secondary titers of serum (poly)glycerolphosphate-specific IgG. Sera from immunized mice enhanced opsonophagocytic killing of live Staphylococcus aureus in vitro. Mice actively immunized with the (poly)glycerolphosphate conjugate vaccine showed rapid clearance of staphylococcal bacteremia in vivo relative to mice similarly immunized with an irrelevant conjugate vaccine. In contrast to purified, natural lipoteichoic acid, the (poly)glycerolphosphate conjugate vaccine itself exhibited no detectable inflammatory activity. These data suggest that a synthetic (poly)glycerolphosphate-based conjugate vaccine will contribute to active protection against extracellular Gram-positive pathogens expressing this highly conserved backbone structure in their membrane-associated lipoteichoic acid. PMID:23649092

  14. Charge states of ions, and mechanisms of charge ordering transitions

    International Nuclear Information System (INIS)

    To gain insight into the mechanism of charge ordering transitions, which conventionally are pictured as a disproportionation of an ion M as 2Mn+→M(n+1)+ + M(n−1)+, we (1) review and reconsider the charge state (or oxidation number) picture itself, (2) introduce new results for the putative charge ordering compound AgNiO2 and the dual charge state insulator AgO, and (3) analyze the cationic occupations of the actual (not formal) charge, and work to reconcile the conundrums that arise. We establish that several of the clearest cases of charge ordering transitions involve no disproportion (no charge transfer between the cations, and hence no charge ordering), and that the experimental data used to support charge ordering can be accounted for within density functional-based calculations that contain no charge transfer between cations. We propose that the charge state picture retains meaning and importance, at least in many cases, if one focuses on Wannier functions rather than atomic orbitals. The challenge of modeling charge ordering transitions with model Hamiltonians isdiscussed. (paper)

  15. Mesoscopic charge quantization

    OpenAIRE

    Aleiner, I.L.; Glazman, L. I.

    1997-01-01

    We study the Coulomb blockade in a chaotic quantum dot connected to a lead by a single channel at nearly perfect transmission. We take into account quantum fluctuations of the dot charge and a finite level spacing for electron states within the dot. Mesoscopic fluctuations of thermodynamic and transport properties in the Coulomb blockade regime exist at any transmission coefficient. In contrast to the previous theories, we show that by virtue of these mesoscopic fluctuations, the Coulomb bloc...

  16. Charged current review

    International Nuclear Information System (INIS)

    Experimental measurements of the τ lifetime and leptonic branching ratios are combined to give updated world averages for these quantities. The results are then used to test the universality of the electroweak charged current couplings to the three lepton species and are found to be consistent with Standard Model predictions at the level of 0.2%, permitting limits to be derived on non-Standard Model physics such as the mass of the τ neutrino

  17. General 2 charge geometries

    CERN Document Server

    Taylor, M

    2006-01-01

    Two charge BPS horizon free supergravity geometries are important in proposals for understanding black hole microstates. In this paper we construct a new class of geometries in the NS1-P system, corresponding to solitonic strings carrying fermionic as well as bosonic condensates. Such geometries are required to account for the full microscopic entropy of the NS1-P system. We then briefly discuss the properties of the corresponding geometries in the dual D1-D5 system.

  18. Relacionamento conjugal e depressão materna

    OpenAIRE

    MayorSotto, Iara Maria Backes de; Piccinini, Cesar Augusto

    2005-01-01

    O presente artigo aborda alguns aspectos teóricos e estudos empíricos sobre a relação entre a qualidade do relacionamento conjugal e a depressão materna. São examinadas as características da depressão materna, sua etiologia multifacetada e possíveis repercussões para o desenvolvimento infantil. Analisa-se especificamente a importância do relacionamento conjugal para uma transição adequada à parentalidade. Os estudos revisados sugerem que há uma combinação de fatores biológicos, obstétricos, s...

  19. Phase conjugate reflection of electromagnetic waves from plasma

    International Nuclear Information System (INIS)

    The interaction of an incoming electromagnetic (EM) wave with two or more EM waves inside a plasma can give rise to a fourth EM wave which is a phase conjugate reflection of the incoming wave. This occurs resonantly if ωa -ωb, the difference frequency of two of the EM waves, along with Ka - kb, the difference wave vector, conforms to one of the plasma dispersion relations, such as that for ion acoustic or Langmuir oscillations. In this case an internal eigenstate of the plasma is excited, and the phase conjugate wave is produced by scattering of the third wave by the density perturbation. (author)

  20. Convexity of Spheres in a Manifold without Conjugate Points

    Indian Academy of Sciences (India)

    Akhil Ranjan; Hemangi Shah

    2002-11-01

    For a non-compact, complete and simply connected manifold without conjugate points, we prove that if the determinant of the second fundamental form of the geodesic spheres in is a radial function, then the geodesic spheres are convex. We also show that if is two or three dimensional and without conjugate points, then, at every point there exists a ray with no focal points on it relative to the initial point of the ray. The proofs use a result from the theory of vector bundles combined with the index lemma.