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Sample records for chiral eft interactions

  1. Symbolic computation of the Hartree-Fock energy from a chiral EFT three-nucleon interaction at N 2LO

    NASA Astrophysics Data System (ADS)

    Gebremariam, B.; Bogner, S. K.; Duguet, T.

    2010-06-01

    We present the first of a two-part Mathematica notebook collection that implements a symbolic approach for the application of the density matrix expansion (DME) to the Hartree-Fock (HF) energy from a chiral effective field theory (EFT) three-nucleon interaction at N 2LO. The final output from the notebooks is a Skyrme-like energy density functional that provides a quasi-local approximation to the non-local HF energy. In this paper, we discuss the derivation of the HF energy and its simplification in terms of the scalar/vector-isoscalar/isovector parts of the one-body density matrix. Furthermore, a set of steps is described and illustrated on how to extend the approach to other three-nucleon interactions. Program summaryProgram title: SymbHFNNN Catalogue identifier: AEGC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 96 666 No. of bytes in distributed program, including test data, etc.: 378 083 Distribution format: tar.gz Programming language: Mathematica 7.1 Computer: Any computer running Mathematica 6.0 and later versions Operating system: Windows Xp, Linux/Unix RAM: 256 Mb Classification: 5, 17.16, 17.22 Nature of problem: The calculation of the HF energy from the chiral EFT three-nucleon interaction at N 2LO involves tremendous spin-isospin algebra. The problem is compounded by the need to eventually obtain a quasi-local approximation to the HF energy, which requires the HF energy to be expressed in terms of scalar/vector-isoscalar/isovector parts of the one-body density matrix. The Mathematica notebooks discussed in this paper solve the latter issue. Solution method: The HF energy from the chiral EFT three-nucleon interaction at N 2LO is cast into a form suitable for an automatic simplification of

  2. Chiral EFT based nuclear forces: achievements and challenges

    NASA Astrophysics Data System (ADS)

    Machleidt, R.; Sammarruca, F.

    2016-08-01

    During the past two decades, chiral effective field theory has become a popular tool to derive nuclear forces from first principles. Two-nucleon interactions have been worked out up to sixth order of chiral perturbation theory and three-nucleon forces up to fifth order. Applications of some of these forces have been conducted in nuclear few- and many-body systems—with a certain degree of success. But in spite of these achievements, we are still faced with great challenges. Among them is the issue of a proper uncertainty quantification of predictions obtained when applying these forces in ab initio calculations of nuclear structure and reactions. A related problem is the order by order convergence of the chiral expansion. We start this review with a pedagogical introduction and then present the current status of the field of chiral nuclear forces. This is followed by a discussion of representative examples for the application of chiral two- and three-body forces in the nuclear many-body system including convergence issues.

  3. Nuclear electromagnetic charge and current operators in Chiral EFT

    SciTech Connect

    Girlanda, Luca; Marcucci, Laura Elisa; Pastore, Saori; Piarulli, Maria; Schiavilla, Rocco; Viviani, Michele

    2013-08-01

    We describe our method for deriving the nuclear electromagnetic charge and current operators in chiral perturbation theory, based on time-ordered perturbation theory. We then discuss possible strategies for fixing the relevant low-energy constants, from the magnetic moments of the deuteron and of the trinucleons, and from the radiative np capture cross sections, and identify a scheme which, partly relying on {Delta} resonance saturation, leads to a reasonable pattern of convergence of the chiral expansion.

  4. Quantum Monte Carlo calculations with chiral effective field theory interactions.

    PubMed

    Gezerlis, A; Tews, I; Epelbaum, E; Gandolfi, S; Hebeler, K; Nogga, A; Schwenk, A

    2013-07-19

    We present the first quantum Monte Carlo (QMC) calculations with chiral effective field theory (EFT) interactions. To achieve this, we remove all sources of nonlocality, which hamper the inclusion in QMC calculations, in nuclear forces to next-to-next-to-leading order. We perform auxiliary-field diffusion Monte Carlo (AFDMC) calculations for the neutron matter energy up to saturation density based on local leading-order, next-to-leading order, and next-to-next-to-leading order nucleon-nucleon interactions. Our results exhibit a systematic order-by-order convergence in chiral EFT and provide nonperturbative benchmarks with theoretical uncertainties. For the softer interactions, perturbative calculations are in excellent agreement with the AFDMC results. This work paves the way for QMC calculations with systematic chiral EFT interactions for nuclei and nuclear matter, for testing the perturbativeness of different orders, and allows for matching to lattice QCD results by varying the pion mass.

  5. Chiral 2N and 3N interactions and quantum Monte Carlo applications

    NASA Astrophysics Data System (ADS)

    Gezerlis, Alexandros

    2016-07-01

    Chiral Effective Field Theory (EFT) two- and three-nucleon forces are now widely employed. Since they were originally formulated in momentum space, these interactions were non-local, making them inaccessible to Quantum Monte Carlo (QMC) methods. We have recently derived a local version of chiral EFT nucleon-nucleon and three-nucleon interactions, which we also used in QMC calculations for neutron matter and light nuclei. In this contribution I go over the basics of local chiral EFT and then summarize recent results.

  6. Chiral symmetry and the nucleon-nucleon interaction

    DOE PAGES

    Machleidt, Ruprecht

    2016-04-20

    We review how nuclear forces emerge from low-energy quantum chromodynamics (QCD) via chiral effective field theory (EFT). During the past two decades, this approach has evolved into a powerful tool to derive nuclear two- and many-body forces in a systematic and model-independent way. We then focus on the nucleon-nucleon (NN) interaction and show in detail how, governed by chiral symmetry, the long- and intermediate-range of the NN potential builds up order by order. We proceed up to sixth order in small momenta, where convergence is achieved. Lastly, the final result allows for a full assessment of the validity of themore » chiral EFT approach to the NN interaction.« less

  7. The two-nucleon electromagnetic charge operator in chiral effective field theory ($\\chi$EFT) up to one loop

    SciTech Connect

    S. Pastore,L. Girlanda,R. Schiavilla,M. Viviani,S. Pastore,L. Girlanda,R. Schiavilla,M. Viviani

    2011-08-01

    The electromagnetic charge operator in a two-nucleon system is derived in chiral effective field theory ($\\chi$EFT) up to order $e\\, Q$ (or N4LO), where $Q$ denotes the low-momentum scale and $e$ is the electric charge. The specific form of the N3LO and N4LO corrections from, respectively, one-pion-exchange and two-pion-exchange depends on the off-the-energy-shell prescriptions adopted for the non-static terms in the corresponding potentials. We show that different prescriptions lead to unitarily equivalent potentials and accompanying charge operators. Thus, provided a consistent set is adopted, predictions for physical observables will remain unaffected by the non-uniqueness associated with these off-the-energy-shell effects.

  8. Threshold pion production in proton-proton collisions at NNLO in chiral EFT

    NASA Astrophysics Data System (ADS)

    Baru, V.; Epelbaum, E.; Filin, A. A.; Hanhart, C.; Krebs, H.; Myhrer, F.

    2016-05-01

    The reaction NN → NN π offers a good testing ground for chiral effective field theory at intermediate energies. It challenges our understanding of the first inelastic channel in nucleon-nucleon scattering and of the charge symmetry breaking pattern in hadronic reactions. In our previous studies, we presented a complete calculation of the pion production operator for s -wave pions up-to-and-including next-to-next-to-leading order (NNLO) in the formulation of chiral effective field theory, which includes pions, nucleons and Δ(1232) degrees of freedom. In this paper we calculate the near-threshold cross section for the pp → d π+ reaction by performing the convolution of the obtained operators with nuclear wave functions based on modern phenomenological and chiral potentials. The available chiral NN wave functions are constructed with a cutoff comparable with the momentum transfer scale inherent in pion production reactions. Hence, a significant portion of the dynamical intermediate-range physics is thereby cut off by them. On the other hand, the NNLO amplitudes evaluated with phenomenological wave functions appear to be largely independent of the NN model used and give corrections to the dominant leading-order contributions as expected from dimensional analysis. The result gives support to the counting scheme used to classify the pion production operators, which is a precondition for a reliable investigation of the chirally suppressed neutral pion production. The explicit inclusion of the Δ(1232) is found to be important but smaller than expected due to cancellations.

  9. Probing Chiral Interactions in Light Nuclei

    SciTech Connect

    Nogga, A; Barrett, B R; Meissner, U; Witala, H; Epelbaum, E; Kamada, H; Navratil, P; Glockle, W; Vary, J P

    2004-01-08

    Chiral two- and three-nucleon interactions are studied in a few-nucleon systems. We investigate the cut-off dependence and convergence with respect to the chiral expansion. It is pointed out that the spectra of light nuclei are sensitive to the three-nucleon force structure. As an example, we present calculations of the 1{sup +} and 3{sup +} states of {sup 6}Li using the no-core shell model approach. The results show contributions of the next-to-next-to-leading order terms to the spectra, which are not correlated to the three-nucleon binding energy prediction.

  10. Long-range interactions between chiral molecules

    SciTech Connect

    Salam, A.

    2015-01-22

    Results of molecular quantum electrodynamics calculations of discriminatory interactions between two chiral molecules undergoing resonance energy transfer, van der Waals dispersion, and optical binding are presented. A characteristic feature of the theory is that the radiation field is quantized with signals consequently propagating between centres at the speed of light. In order to correctly describe optically active chromophores, it is necessary to include magnetic as well as electric dipole coupling terms in the time-dependent perturbation theory computations. Recent work investigating the effect of an absorptive and dispersive chiral medium on the rate of migration of energy will also be discussed.

  11. The 4He Total Photo-Absorption Cross Section With Two- Plus Three-Nucleon Interactions From Chiral Effective Field Theory

    SciTech Connect

    Quaglioni, S; Navratil, P

    2007-03-09

    The total photo-absorption cross section of {sup 4}He is evaluated microscopically using two- (NN) and three-nucleon (NNN) interactions based upon chiral effective field theory ({chi}EFT). The calculation is performed using the Lorentz integral transform method along with the ab initio no-core shell model approach. An important feature of the present study is the consistency of the NN and NNN interactions and also, through the Siegert theorem, of the two- and three-body current operators. This is due to the application of the {chi}EFT framework. The inclusion of the NNN interaction produces a suppression of the peak height and enhancement of the tail of the cross section. We compare to calculations obtained using other interactions and to representative experiments. The rather confused experimental situation in the giant resonance region prevents discrimination among different interaction models.

  12. Chiral Sensitivity in Electron-Molecule Interactions

    NASA Astrophysics Data System (ADS)

    Dreiling, Joan

    2015-09-01

    All molecular forms of life possess a chiral asymmetry, with amino acids and sugars found respectively in L- and D-enantiomers only. The primordial origin of this enantiomeric excess is unknown. One possible explanation is given by the Vester- Ulbricht hypothesis, which suggests that left-handed electrons present in beta-radiation, produced by parity-violating weak decays, interacted with biological precursors and preferentially destroyed one of the two enantiomers. Experimental tests of this idea have thus far yielded inconclusive results. We show direct evidence for chirally-dependent bond breaking through a dissociative electron attachment (DEA) reaction when spin-polarized electrons are incident on gas-phase chiral molecules. This provides unambiguous evidence for a well-defined, chirally-sensitive destructive molecular process and, as such, circumstantial evidence for the Vester-Ulbricht hypothesis. I will also present the results of our systematic study of the DEA asymmetry for different chiral halocamphor molecules. Three halocamphor molecules were investigated: 3-bromocamphor (C10H15BrO), 3-iodocamphor(C10H15IO), and 10-iodocamphor. The DEA asymmetries collected for bromocamphor and iodocamphor are qualitatively different, suggesting that the atomic number of the heaviest atom in the molecule plays a crucial role in the asymmetric interactions. The DEA asymmetry data for 3- and 10-iodocamphor have the same qualitative behavior, but the 10-iodocamphor asymmetry is about twice as large at the lowest energies investigated, so the location of the heavy atom in the camphor molecule also affects the asymmetries. This work was performed at the University of Nebraska-Lincoln. This project is funded by NSF Grant PHY-1206067.

  13. Chiral Light-Matter Interaction in Optical Resonators.

    PubMed

    Yoo, SeokJae; Park, Q-Han

    2015-05-22

    The Purcell effect explains the modification of the spontaneous decay rate of quantum emitters in a resonant cavity. For quantum emitters such as chiral molecules, however, the cavity modification of the spontaneous decay rate has been little known. Here we extend Purcell's work to the chiral light-matter interaction in optical resonators and find the differential spontaneous decay rate of chiral molecules coupled to left and right circularly polarized resonator modes. We determine the chiral Purcell factor, which characterizes the ability of optical resonators to enhance chiroptical signals, by the quality factor and the chiral mode volume of a resonator, representing, respectively, the temporal confinement of light and the spatial confinement of the helicity of light. We show that the chiral Purcell effect can be applied to chiroptical spectroscopy. Specifically, we propose a realistic scheme to achieve resonator enhanced chiroptical spectroscopy that uses the double fishnet structure as a nanoscale cuvette supporting the chiral Purcell effect.

  14. Emergence of Chirality from Isotropic Interactions of Three Length Scales

    NASA Astrophysics Data System (ADS)

    Mkhonta, S. K.; Elder, K. R.; Huang, Zhi-Feng

    2016-05-01

    Chirality is known to play a pivotal role in determining material properties and functionalities. However, it remains a great challenge to understand and control the emergence of chirality and the related enantioselective process particularly when the building components of the system are achiral. Here we explore the generic mechanisms driving the formation of two-dimensional chiral structures in systems characterized by isotropic interactions and three competing length scales. We demonstrate that starting from isotropic and rotationally invariant interactions, a variety of chiral ordered patterns and superlattices with anisotropic but achiral units can self-assemble. The mechanisms for selecting specific states are related to the length-scale coupling and the selection of resonant density wave vectors. Sample phase diagrams and chiral elastic properties are identified. These findings provide a viable route for predicting chiral phases and selecting the desired handedness.

  15. Renormalization of NN Interaction with Relativistic Chiral Two Pion Exchange

    SciTech Connect

    Higa, R; Valderrama, M Pavon; Arriola, E Ruiz

    2007-06-14

    The renormalization of the NN interaction with the Chiral Two Pion Exchange Potential computed using relativistic baryon chiral perturbation theory is considered. The short distance singularity reduces the number of counter-terms to about a half as those in the heavy-baryon expansion. Phase shifts and deuteron properties are evaluated and a general overall agreement is observed.

  16. Plasmonic enhancement of chiral light-matter interactions

    NASA Astrophysics Data System (ADS)

    Alizadeh, Mohammadhossein

    Plasmonic nanostructures provide unique opportunities to improve the detection limits of chiroptical spectroscopies by enhancing chiral light-matter interactions. The most significant of such interaction occur in ultraviolet (UV) range of the electromagnetic spectrum that remains challenging to access by conventional localized plasmon resonance based sensors. Although Surface Plasmon Polaritons (SPPs) on noble metal films can sustain resonances in the desired spectral range, their transverse magnetic nature has been an obstacle for enhancing chiroptical effects. We demonstrate, both analytically and numerically, that SPPs excited by near-field sources can exhibit rich and non-trivial chiral characteristics. In particular, we show that the excitation of SPPs by a chiral source not only results in a locally enhanced optical chirality but also achieves manifold enhancement of net optical chirality. Our finding that SPPs facilitate a plasmonic enhancement of optical chirality in the UV part of the spectrum is of great interest in chiral bio-sensing. Next we focus on the new concepts of transverse spin angular momentum and Belinfante spin momentum of evanescent waves, which have recently drawn considerable attention. We investigate these novel physical properties of electromagnetic fields in the context of chiral surface plasmon polaritons. We demonstrate, both analytically and numerically, that locally excited surface plasmon polaritons possess transverse Spin angular momentum and Belinfante momentum with rich and non-trivial characteristics. We also show that the transverse spin angular momentum of locally excited surface plasmon polaritons leads to the emergence of transverse chiral forces in opposite directions for chiral objects of different handedness. The magnitude of such a transverse force is comparable to the optical gradient force and scattering forces. This finding may pave the way for realization of optical separation of chiral biomolecules.

  17. Tailoring the chiral magnetic interaction between two individual atoms

    PubMed Central

    Khajetoorians, A. A.; Steinbrecher, M.; Ternes, M.; Bouhassoune, M.; dos Santos Dias, M.; Lounis, S.; Wiebe, J.; Wiesendanger, R.

    2016-01-01

    Chiral magnets are a promising route towards dense magnetic storage technology due to their inherent nano-scale dimensions and energy efficient properties. Engineering chiral magnets requires atomic-level control of the magnetic exchange interactions, including the Dzyaloshinskii–Moriya interaction, which defines a rotational sense for the magnetization of two coupled magnetic moments. Here we show that the indirect conduction electron-mediated Dzyaloshinskii–Moriya interaction between two individual magnetic atoms on a metallic surface can be manipulated by changing the interatomic distance with the tip of a scanning tunnelling microscope. We quantify this interaction by comparing our measurements to a quantum magnetic model and ab-initio calculations yielding a map of the chiral ground states of pairs of atoms depending on the interatomic separation. The map enables tailoring the chirality of the magnetization in dilute atomic-scale magnets. PMID:26902332

  18. Chiral susceptibility in an effective interaction model

    SciTech Connect

    Min He; Yu Jiang; Sun Weimin; Zong Hongshi

    2008-04-01

    A closed integral expression for the chiral susceptibility at finite temperature is derived. The corresponding disconnected part, which proves to be of major physical relevance and free from the additive quadratic ultraviolet divergence, is identified. Then a calculation based on an effective model gluon propagator is conducted within the framework of the Dyson-Schwinger equations for two flavors in the chiral limit. A narrow, divergent peak is observed as temperature varies, and its implications are discussed.

  19. Running of the contact interactions in chiral N3LO potentials from subtractive renormalization

    NASA Astrophysics Data System (ADS)

    Batista, E. F.; Szpigel, S.; Timóteo, V. S.

    2015-07-01

    In this work a subtracted kernel renormalization procedure (SKM) is applied to the chiral NN potential up to next-to-next-to-next-to-leading-order (N3 LO) to obtain the running of the renormalized contact strengths with the subtraction scale μ and the phase shifts for all uncoupled waves with contact interaction (S,P,D). We use two potentials constructed within the framework of Weinberg's approach to ChEFT, which provide a very accurate description of NN scattering data below laboratory energies E ∼ 350 MeV, namely Epelbaum, Glöckle and Meissner (N3LO-EGM) and Entem and Machleidt (N3LO-EM). For both potentials, we consider a large cutoff (30 fm-1) and analyze the phases and the running of the contact strengths with the subtraction point μ by making a fit of the K-matrix with five subtractions to the K-matrix from the Nijmegen II potential at low energies (E ≤ 20 MeV).

  20. Self-consistent Models of Strong Interaction with Chiral Symmetry

    DOE R&D Accomplishments Database

    Nambu, Y.; Pascual, P.

    1963-04-01

    Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)

  1. Effective KN interaction based on chiral SU(3) dynamics

    SciTech Connect

    Hyodo, Tetsuo; Weise, Wolfram

    2008-03-15

    The effective KN interaction based on chiral SU(3) coupled-channel dynamics is derived and its extrapolation below the KN threshold is studied in detail. Starting from the coupled-channel scattering equations, we eliminate the channels other than KN and obtain an effective interaction in the single KN channel. An equivalent local potential in coordinate space is constructed such as to reproduce the full scattering amplitude of the chiral SU(3) coupled-channel framework. We discuss several realistic chiral SU(3)-based models in comparison to reach conclusions about the uncertainties involved. It turns out that, in the region relevant to the discussion of deeply bound K-nuclear few-body systems, the resulting energy-dependent, equivalent local potential is substantially less attractive than the one suggested in previous purely phenomenological treatments.

  2. EFT for DFT

    NASA Astrophysics Data System (ADS)

    Furnstahl, R. J.

    These lectures give an overview of the ongoing application of effective field theory (EFT) and renormalization group (RG) concepts and methods to density functional theory (DFT), with special emphasis on the nuclear many-body problem. Many of the topics covered are still in their infancy, so rather than a complete review these lectures aim to provide an introduction to the developing literature.

  3. Tailoring the chiral magnetic interaction between two individual atoms

    NASA Astrophysics Data System (ADS)

    Wiebe, J.; Khajetoorians, A. A.; Steinbrecher, M.; Ternes, M.; Bouhassoune, M.; Dos Santos Dias, M.; Lounis, S.; Wiesendanger, R.

    Chiral magnets are a promising route toward dense magnetic storage technology due to their inherent nano-scale dimensions and energy efficient properties. Engineering chiral magnets requires atomic-level control of the magnetic exchange interactions, including the Dzyaloshinskii-Moriya interaction, which defines a rotational sense for the magnetization of two coupled magnetic moments. Here we show that the indirect conduction electron mediated Dzyaloshinskii-Moriya interaction between two individual magnetic atoms on a metallic surface can be manipulated by changing the interatomic distance with the tip of a scanning tunneling microscope. We quantify this interaction by comparing our measurements to a quantum magnetic model and ab-initio calculations yielding a map of the chiral ground states of pairs of atoms depending on the interatomic separation. The map enables tailoring the chirality of the magnetization in dilute atomic-scale magnets. Acknowledgements: SFB668, GrK1286, SFB767, LO 1659 5-1, Emmy Noether Program of the DFG, FOM of NWO, VH-NG-717.

  4. Interaction of chiral rafts in self-assembled colloidal membranes

    NASA Astrophysics Data System (ADS)

    Xie, Sheng; Hagan, Michael F.; Pelcovits, Robert A.

    2016-03-01

    Colloidal membranes are monolayer assemblies of rodlike particles that capture the long-wavelength properties of lipid bilayer membranes on the colloidal scale. Recent experiments on colloidal membranes formed by chiral rodlike viruses showed that introducing a second species of virus with different length and opposite chirality leads to the formation of rafts—micron-sized domains of one virus species floating in a background of the other viruses [Sharma et al., Nature (London) 513, 77 (2014), 10.1038/nature13694]. In this article we study the interaction of such rafts using liquid crystal elasticity theory. By numerically minimizing the director elastic free energy, we predict the tilt angle profile for both a single raft and two rafts in a background membrane, and the interaction between two rafts as a function of their separation. We find that the chiral penetration depth in the background membrane sets the scale for the range of the interaction. We compare our results with the experimental data and find good agreement for the strength and range of the interaction. Unlike the experiments, however, we do not observe a complete collapse of the data when rescaled by the tilt angle at the raft edge.

  5. Reducible chiral four-body interactions in nuclear matter

    NASA Astrophysics Data System (ADS)

    Kaiser, N.; Milkus, R.

    2016-01-01

    The method of unitary transformations generates five classes of leading-order reducible chiral four-nucleon interactions which involve pion exchanges and a spin-spin contact term. Their first-order contributions to the energy per particle of isospin-symmetric nuclear matter and pure neutron matter are evaluated in detail. For most of the closed four-loop diagrams the occurring integrals over four Fermi spheres can be reduced to easily manageable one- or two-parameter integrals. One finds substantial compensations among the different contributions arising from 2-ring and 1-ring diagrams. Altogether, the net attraction generated by the chiral four-nucleon interaction does not exceed values of -1.3 MeV for densities ρ < 2ρ0.

  6. Electromagnetic interactions in a chiral effective lagrangian for nuclei

    SciTech Connect

    Serot, Brian D.

    2007-12-15

    Electromagnetic (EM) interactions are incorporated in a recently proposed effective field theory of the nuclear many-body problem. Earlier work with this effective theory exhibited EM couplings that are correct only to lowest order in both the pion fields and the electric charge. The Lorentz-invariant effective field theory contains nucleons, pions, isoscalar scalar ({sigma}) and vector ({omega}) fields, and isovector vector ({rho}) fields. The theory exhibits a nonlinear realization of SU(2){sub L} x SU(2){sub R} chiral symmetry and has three desirable features: it uses the same degrees of freedom to describe the currents and the strong-interaction dynamics, it satisfies the symmetries of the underlying QCD, and its parameters can be calibrated using strong-interaction phenomena, like hadron scattering or the empirical properties of finite nuclei. It has been verified that for normal nuclear systems, the effective lagrangian can be expanded systematically in powers of the meson fields (and their derivatives) and can be truncated reliably after the first few orders. The complete EM lagrangian arising from minimal substitution is derived and shown to possess the residual chiral symmetry of massless, two-flavor QCD with EM interactions. The uniqueness of the minimal EM current is proved, and the properties of the isovector vector and axial-vector currents are discussed, generalizing earlier work. The residual chiral symmetry is maintained in additional (non-minimal) EM couplings expressed as a derivative expansion and in implementing vector meson dominance. The role of chiral anomalies in the EM lagrangian is briefly discussed.

  7. Interaction of Two Filament Channels of Different Chiralities

    NASA Astrophysics Data System (ADS)

    Joshi, Navin Chandra; Filippov, Boris; Schmieder, Brigitte; Magara, Tetsuya; moon, Young-Jae; Uddin, Wahab

    2016-07-01

    We present observations of the interactions between the two filament channels of different chiralities and associated dynamics that occurred during 2014 April 18-20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at first glance show that the heated plasma is moving from one filament channel to the other. The SDO/AIA 171 Å observations and the potential-field source-surface magnetic field extrapolation reveal the presence of a fan-spine magnetic configuration over the filament channels with a null point located above them. Three different events of filament activations, partial eruptions, and associated filament channel interactions have been observed. The activation initiated in one filament channel seems to propagate along the neighboring filament channel. We believe that the activation and partial eruption of the filaments brings the field lines of flux ropes containing them closer to the null point and triggers the magnetic reconnection between them and the fan-spine magnetic configuration. As a result, the hot plasma moves along the outer spine line toward the remote point. Utilizing the present observations, for the first time we have discussed how two different-chirality filament channels can interact and show interrelation.

  8. Peripheral NN scattering from subtractive renormalization of chiral interactions

    SciTech Connect

    Batista, E. F.; Szpigel, S.; Timóteo, V. S.

    2014-11-11

    We apply five subtractions in the Lippman-Schwinger (LS) equation in order to perform a non-perturbative renormalization of chiral N3LO nucleon-nucleon interactions. Here we compute the phase shifts for the uncoupled peripheral waves at renormalization scales between 0.1 fm{sup −1} and 1 fm{sup −1}. In this range, the results are scale invariant and provide an overall good agreement with the Nijmegen partial wave analysis up to at least E{sub lab} = 150 MeV, with a cutoff at Λ = 30 fm{sup −1}.

  9. Distinguishability and chiral stability in solution: Effects of decoherence and intermolecular interactions

    SciTech Connect

    Han, Heekyung; Wardlaw, David M.; Frolov, Alexei M.

    2014-05-28

    We examine the effect of decoherence and intermolecular interactions (chiral discrimination energies) on the chiral stability and the distinguishability of initially pure versus mixed states in an open chiral system. Under a two-level approximation for a system, intermolecular interactions are introduced by a mean-field theory, and interaction between a system and an environment is modeled by a continuous measurement of a population difference between the two chiral states. The resultant equations are explored for various parameters, with emphasis on the combined effects of the initial condition of the system, the chiral discrimination energies, and the decoherence in determining: the distinguishability as measured by a population difference between the initially pure and mixed states, and the decoherence process; the chiral stability as measured by the purity decay; and the stationary state of the system at times long relative to the time scales of the system dynamics and of the environmental effects.

  10. On the deracemization of a chiral molecular beam by interaction with circularly polarized light

    NASA Astrophysics Data System (ADS)

    Kucirka, Jerry; Shekhtman, Alexander G.

    1996-02-01

    A strong electromagnetic field exerts a force on neutral atoms or molecules and this effect has been utilized in atomic beam optics to create the analogs to optical elements such as lenses and mirrors. We extend this concept to the specific interaction of a chiral molecule with a circularly polarized laser wave. Because of the optical activity of chiral molecules this interaction is selective with respect to handedness and this selectivity forms the basis for a “chiral mirror” scheme, here introduced, to produce chirally pure matter.

  11. Accurate nuclear radii and binding energies from a chiral interaction

    SciTech Connect

    Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold

    2015-05-01

    With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shell nuclei are in reasonable agreement with experiment.

  12. Accurate nuclear radii and binding energies from a chiral interaction

    DOE PAGES

    Ekstrom, Jan A.; Jansen, G. R.; Wendt, Kyle A.; Hagen, Gaute; Papenbrock, Thomas F.; Carlsson, Boris; Forssen, Christian; Hjorth-Jensen, M.; Navratil, Petr; Nazarewicz, Witold

    2015-05-01

    With the goal of developing predictive ab initio capability for light and medium-mass nuclei, two-nucleon and three-nucleon forces from chiral effective field theory are optimized simultaneously to low-energy nucleon-nucleon scattering data, as well as binding energies and radii of few-nucleon systems and selected isotopes of carbon and oxygen. Coupled-cluster calculations based on this interaction, named NNLOsat, yield accurate binding energies and radii of nuclei up to 40Ca, and are consistent with the empirical saturation point of symmetric nuclear matter. In addition, the low-lying collective Jπ=3- states in 16O and 40Ca are described accurately, while spectra for selected p- and sd-shellmore » nuclei are in reasonable agreement with experiment.« less

  13. Properties of interacting 2D chiral tensor network states

    NASA Astrophysics Data System (ADS)

    Bradlyn, Barry; Dubail, Jerome; Read, Nicholas

    2015-03-01

    In a recent paper, Dubail and Read gave a construction for free fermion tensor network states(TNSs) in the chiral p + ip and ν = 1 Chern insulator topological phases in two dimensions, and gave a generalization to Laughlin-like states. However, on general principles these free fermion states must be ground states of gapless local Hamiltonians. In this talk, we address the issue of the energy gap in the interacting states, with a particular focus on the ν = 1 / 2 bosonic Laughlin-like TNS. Through a combination of analytic and numerical arguments, we will show that these states too have gapless local parent Hamiltonians. Nevertheless, we will explore to what degree they can be used as numerical approximations to gapped phases.

  14. Regulator artifacts in uniform matter for chiral interactions

    NASA Astrophysics Data System (ADS)

    Dyhdalo, A.; Furnstahl, R. J.; Hebeler, K.; Tews, I.

    2016-09-01

    Regulator functions applied to two- and three-nucleon forces are a necessary ingredient in many-body calculations based on chiral effective field theory interactions. These interactions have been developed recently with a variety of different cutoff forms, including regulating both the momentum transfer (local) and the relative momentum (nonlocal). While in principle any regulator that suppresses high-momentum modes can be employed, in practice artifacts are inevitable in current power counting schemes. Artifacts from particular regulators may cause significant distortions of the physics or may affect many-body convergence rates, so understanding their nature is important. Here we characterize the differences between cutoff effects using uniform matter at Hartree-Fock and second order in the interaction as a test-bed. This provides a clean laboratory to isolate phase-space effects of various regulators on both two- and three-nucleon interactions. We test the normal-ordering approximation for three-nucleon forces in nuclear matter and find that the relative size of the residual 3 N contributions is sensitive to the employed regularization scheme.

  15. Plasmon-induced strong interaction between chiral molecules and orbital angular momentum of light

    PubMed Central

    Wu, Tong; Wang, Rongyao; Zhang, Xiangdong

    2015-01-01

    Whether or not chiral interaction exists between the optical orbital angular momentum (OAM) and a chiral molecule remains unanswered. So far, such an interaction has not been observed experimentally. Here we present a T-matrix method to study the interaction between optical OAM and the chiral molecule in a cluster of nanoparticles. We find that strong interaction between the chiral molecule and OAM can be induced by the excitation of plasmon resonances. An experimental scheme to observe such an interaction has been proposed. Furthermore, we have found that the signal of the OAM dichroism can be either positive or negative, depending on the spatial positions of nanocomposites in the cross-sections of OAM beams. The cancellation between positive and negative signals in the spatial average can explain why the interaction has not been observed in former experiments. PMID:26656892

  16. Chiral magnetic conductivity in an interacting lattice model of parity-breaking Weyl semimetal

    NASA Astrophysics Data System (ADS)

    Buividovich, P. V.; Puhr, M.; Valgushev, S. N.

    2015-11-01

    We report on the mean-field study of the chiral magnetic effect (CME) in static magnetic fields within a simple model of parity-breaking Weyl semimetal given by the lattice Wilson-Dirac Hamiltonian with constant chiral chemical potential. We consider both the mean-field renormalization of the model parameters and nontrivial corrections to the CME originating from resummed ladder diagrams with arbitrary number of loops. We find that onsite repulsive interactions affect the chiral magnetic conductivity almost exclusively through the enhancement of the renormalized chiral chemical potential. Our results suggest that nontrivial corrections to the chiral magnetic conductivity due to interfermion interactions are not relevant in practice since they only become important when the CME response is strongly suppressed by the large gap in the energy spectrum.

  17. Spontaneous chiral resolution directed by symmetry restriction and π-π interaction

    NASA Astrophysics Data System (ADS)

    Yu, Jin-Tao; Shi, Yan-Yan; Sun, Junliang; Lin, Jianhua; Huang, Zhi-Tang; Zheng, Qi-Yu

    2013-10-01

    In order to understand and rationally construct homochiral self-assembled structures from racemic molecules, two novel crystalline metal-organic frameworks with chiral cavities were developed. The homochirality of the layers in both MOFs was achieved by forming strong coordinate bonds between the C3-symmetric cyclotriveratrylene and Zn4O(CO2)6 cluster. By changing weak π-π interactions between organic building blocks, the achiral assembly of ZnCTV-1 was successfully transformed into a chiral assembly in ZnCTV-2. This study demonstrated a possible route for designing the synthesis of chiral MOF through weak interactions.

  18. Molecular chirality and chiral capsule-type dimer formation of cyclic triamides via hydrogen-bonding interactions.

    PubMed

    Fujimoto, Noriko; Matsumura, Mio; Azumaya, Isao; Nishiyama, Shizuka; Masu, Hyuma; Kagechika, Hiroyuki; Tanatani, Aya

    2012-05-18

    Chiral properties of bowl-shaped cyclic triamides bearing functional groups with hydrogen-bonding ability were examined. Chiral induction of cyclic triamide 3a was observed by addition of chiral amine in solution, and chiral separation was achieved by simple crystallization to afford chiral capsule-type dimer structure of 4a.

  19. Friction-induced enhancement in the optical activity of interacting chiral molecules

    NASA Astrophysics Data System (ADS)

    Bargueño, Pedro; Peñate-Rodríguez, Helen C.; Gonzalo, Isabel; Sols, Fernando; Miret-Artés, Salvador

    2011-11-01

    The stability of chiral molecules described by a non-linear two-state system which accounts for mean-field interactions between different isomers, including any external chiral influence (in particular, the parity violating energy difference) is investigated. By introducing the population and phase difference of the chiral states as a pair of canonical variables, driving an analogy to a bosonic Josephson junction, our study to include dissipative effects in condensed phase described by a Caldeira-Leggett like Hamiltonian is extended using the Langevin formalism. Dissipative effects produce an enhancement in the population difference, not leading to racemization.

  20. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    DOE PAGES

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  1. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    SciTech Connect

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  2. Nematicons deflection through interaction with disclination lines in chiral nematic liquid crystals

    SciTech Connect

    Laudyn, Urszula A.; Karpierz, Miroslaw A.

    2013-11-25

    In this work, we study experimentally the interaction of spatial optical soliton in chiral nematic liquid crystals with disclination line created in a wedge shaped cell. We show that in most cases the self-confined beam preserves this interaction. We demonstrate that this interaction can be employed for efficient bending of the soliton trajectory, as a result of reflection and refraction.

  3. Quantum Monte Carlo calculations of neutron matter with chiral three-body forces

    DOE PAGES

    Tews, I.; Gandolfi, Stefano; Gezerlis, A.; Schwenk, A.

    2016-02-02

    Chiral effective field theory (EFT) enables a systematic description of low-energy hadronic interactions with controlled theoretical uncertainties. For strongly interacting systems, quantum Monte Carlo (QMC) methods provide some of the most accurate solutions, but they require as input local potentials. We have recently constructed local chiral nucleon-nucleon (NN) interactions up to next-to-next-to-leading order (N2LO). Chiral EFT naturally predicts consistent many-body forces. In this paper, we consider the leading chiral three-nucleon (3N) interactions in local form. These are included in auxiliary field diffusion Monte Carlo (AFDMC) simulations. We present results for the equation of state of neutron matter and for themore » energies and radii of neutron drops. Specifically, we study the regulator dependence at the Hartree-Fock level and in AFDMC and find that present local regulators lead to less repulsion from 3N forces compared to the usual nonlocal regulators.« less

  4. Surface mediated chiral interactions between cyclodextrins and propranolol enantiomers: a SERS and DFT study.

    PubMed

    Stiufiuc, Rares; Iacovita, Cristian; Stiufiuc, Gabriela; Bodoki, Ede; Chis, Vasile; Lucaciu, Constantin M

    2015-01-14

    The nanoparticles mediated enantioselective recognition of propranolol enantiomers through native cyclodextrin complexation has been investigated by using surface-enhanced Raman spectroscopy (SERS). The highly efficient chiral recognition mechanism is based on a synergistic interaction between spherical noble metal nanoparticles, propranolol enantiomers and native cyclodextrins (CDs). Amongst the native cyclodextrins, β-CD has the highest chiral recognition ability for propranolol enantiomers, due to its specific shape and cavity size, thus producing the largest difference between the recorded SERS spectra of the two hosted enantiomers. The molecular interaction mechanism responsible for enantioselectivity was furthermore proven by quantum chemical calculations based on density functional theory (DFT). The theoretical calculations and experimental SER spectra allowed the assignment of functional moieties involved in the chiral recognition mechanism. The most important factors governing the highly efficient chiral probing by SERS are the fundamentally different mechanism of interaction between the R- and S-enantiomers and β-CD and the strength of interaction between the nanoparticle surface and the two propranolol-CD complexes. The role of metallic nanoparticles in the enantioselective recognition process has been experimentally evaluated by using silver and gold nanoparticles as SERS substrates, given their ability to interact differently with the complexes. The viability of this new method for chiral discrimination has been demonstrated for both substrates and could open new avenues for these kinds of applications.

  5. Sensitivities and correlations of nuclear structure observables emerging from chiral interactions

    NASA Astrophysics Data System (ADS)

    Calci, Angelo; Roth, Robert

    2016-07-01

    Starting from a set of different two- and three-nucleon interactions from chiral effective field theory, we use the importance-truncated no-core shell model for ab initio calculations of excitation energies as well as electric quadrupole (E 2 ) and magnetic dipole (M 1 ) moments and transition strengths for selected p -shell nuclei. We explore the sensitivity of the excitation energies to the chiral interactions as a first step towards and systematic uncertainty propagation from chiral inputs to nuclear structure observables. The uncertainty band spanned by the different chiral interactions is typically in agreement with experimental excitation energies, but we also identify observables with notable discrepancies beyond the theoretical uncertainty that reveal insufficiencies in the chiral interactions. For electromagnetic observables we identify correlations among pairs of E 2 or M 1 observables based on the ab initio calculations for the different interactions. We find extremely robust correlations for E 2 observables and illustrate how these correlations can be used to predict one observable based on an experimental datum for the second observable. In this way we circumvent convergence issues and arrive at far more accurate results than any direct ab initio calculation. A prime example for this approach is the quadrupole moment of the first 2+ state in 12C, which is predicted with an drastically improved accuracy.

  6. Three-dimensional chiral skyrmions with attractive interparticle interactions

    NASA Astrophysics Data System (ADS)

    Leonov, A. O.; Monchesky, T. L.; Loudon, J. C.; Bogdanov, A. N.

    2016-09-01

    We introduce a new class of isolated three-dimensional skyrmion that can occur within the cone phase of chiral magnetic materials. These novel solitonic states consist of an axisymmetric core separated from the host phase by an asymmetric shell. These skyrmions attract one another. We derive regular solutions for isolated skyrmions arising in the cone phase of cubic helimagnets and investigate their bound states.

  7. 48 CFR 832.1106 - EFT mechanisms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false EFT mechanisms. 832.1106 Section 832.1106 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING Electronic Funds Transfer 832.1106 EFT mechanisms. (a) The Assistant...

  8. Chiral two-body currents in nuclei: Gamow-Teller transitions and neutrinoless double-beta decay.

    PubMed

    Menéndez, J; Gazit, D; Schwenk, A

    2011-08-01

    We show that chiral effective field theory (EFT) two-body currents provide important contributions to the quenching of low-momentum-transfer Gamow-Teller transitions, and use chiral EFT to predict the momentum-transfer dependence that is probed in neutrinoless double-beta (0νββ) decay. We then calculate for the first time the 0νββ decay operator based on chiral EFT currents and study the nuclear matrix elements at successive orders. The contributions from chiral two-body currents are significant and should be included in all calculations. PMID:21902315

  9. Exploring the chiral regime of QCD in the interacting instanton liquid model

    SciTech Connect

    Cristoforetti, M.; Faccioli, P.; Traini, M. C.; Negele, J. W.

    2007-02-01

    The interacting instanton liquid model (IILM) is used to explore the role of instanton-induced dynamics in hadron structure. To support the validity of this model in the chiral regime, the quark mass dependencies of several properties are shown to agree with chiral perturbation theory, including the density of eigenmodes of the Dirac operator and the mass of the pion. A quark mass m*=80 MeV emerging naturally from the model is shown to specify the mass scale above which the fermion determinant is suppressed, the zero modes become subdominant, and the density of quasizero modes become independent of the quark mass.

  10. Manifestations of electron interactions in photogalvanic effect in chiral nanotubes

    NASA Astrophysics Data System (ADS)

    Matthews, Raphael; Agam, Oded; Andreev, Anton; Spivak, Boris

    2012-05-01

    Carbon nanotubes provide one of the most accessible experimental realizations of one-dimensional electron systems. In the experimentally relevant regime of low doping, the Luttinger liquid formed by electrons may be approximated by a Wigner crystal. The crystal-like electronic order suggests that nanotubes exhibit effects similar to the Mössbauer effect where the momentum of an emitted photon is absorbed by the whole crystal. We show that the circular photovoltaic effect in chiral nanotubes is of the same nature. We obtain the frequency dependence of the photovoltage and characterize its singularities in a broad frequency range where the electron correlations are essential. Our predictions provide a basis for using the photogalvanic effect as a new experimental probe of electron correlations in nanotubes.

  11. Distinct Clinical Phenotypes Associated with a Mutation in the Mitochondrial Translation Elongation Factor EFTs

    PubMed Central

    Smeitink, Jan A. M.; Elpeleg, Orly; Antonicka, Hana; Diepstra, Heleen; Saada, Ann; Smits, Paulien; Sasarman, Florin; Vriend, Gert; Jacob-Hirsch, Jasmine; Shaag, Avraham; Rechavi, Gideon; Welling, Brigitte; Horst, Jürgen; Rodenburg, Richard J.; van den Heuvel, Bert; Shoubridge, Eric A.

    2006-01-01

    The 13 polypeptides encoded in mitochondrial DNA (mtDNA) are synthesized in the mitochondrial matrix on a dedicated protein-translation apparatus that resembles that found in prokaryotes. Here, we have investigated the genetic basis for a mitochondrial protein-synthesis defect associated with a combined oxidative phosphorylation enzyme deficiency in two patients, one of whom presented with encephalomyopathy and the other with hypertrophic cardiomyopathy. Sequencing of candidate genes revealed the same homozygous mutation (C997T) in both patients in TSFM, a gene coding for the mitochondrial translation elongation factor EFTs. EFTs functions as a guanine nucleotide exchange factor for EFTu, another translation elongation factor that brings aminoacylated transfer RNAs to the ribosomal A site as a ternary complex with guanosine triphosphate. The mutation predicts an Arg333Trp substitution at an evolutionarily conserved site in a subdomain of EFTs that interacts with EFTu. Molecular modeling showed that the substitution disrupts local subdomain structure and the dimerization interface. The steady-state levels of EFTs and EFTu in patient fibroblasts were reduced by 75% and 60%, respectively, and the amounts of assembled complexes I, IV, and V were reduced by 35%–91% compared with the amounts in controls. These phenotypes and the translation defect were rescued by retroviral expression of either EFTs or EFTu. These data clearly establish mutant EFTs as the cause of disease in these patients. The fact that the same mutation is associated with distinct clinical phenotypes suggests the presence of genetic modifiers of the mitochondrial translation apparatus. PMID:17033963

  12. Testing semilocal chiral two-nucleon interaction in selected electroweak processes

    NASA Astrophysics Data System (ADS)

    Skibiński, R.; Golak, J.; Topolnicki, K.; Witała, H.; Epelbaum, E.; Krebs, H.; Kamada, H.; Meißner, Ulf-G.; Nogga, A.

    2016-06-01

    The recently developed semilocal improved chiral nucleon-nucleon interaction is used for the first time to study several electromagnetic and weak processes at energies below the pion production threshold. Cross sections and selected polarization observables for deuteron photodisintegration, nucleon-deuteron radiative capture, three-body 3He photodisintegration, as well as capture rates for decays of the muonic 2H and 3He atoms are calculated. The Lippmann-Schwinger and Faddeev equations in momentum space are solved to obtain nuclear states. The electromagnetic current operator is taken as a single nucleon current supplemented by many-body contributions induced via the Siegert theorem. For muon capture processes the nonrelativistic weak current together with the dominant relativistic corrections is used. Our results compare well with experimental data, demonstrating the same quality as is observed for the semiphenomenological Argonne V18 potential. Compared to the older version of the chiral potential with a nonlocal regularization, a much smaller cut-off dependence is found for the state-of-art chiral local interaction employed in this paper. Finally, estimates of errors due to the truncation of the chiral expansion are given.

  13. Chiral Three-Nucleon Interactions in Light Nuclei, Neutron-α Scattering, and Neutron Matter.

    PubMed

    Lynn, J E; Tews, I; Carlson, J; Gandolfi, S; Gezerlis, A; Schmidt, K E; Schwenk, A

    2016-02-12

    We present quantum Monte Carlo calculations of light nuclei, neutron-α scattering, and neutron matter using local two- and three-nucleon (3N) interactions derived from chiral effective field theory up to next-to-next-to-leading order (N(2)LO). The two undetermined 3N low-energy couplings are fit to the (4)He binding energy and, for the first time, to the spin-orbit splitting in the neutron-α P-wave phase shifts. Furthermore, we investigate different choices of local 3N-operator structures and find that chiral interactions at N(2)LO are able to simultaneously reproduce the properties of A=3,4,5 systems and of neutron matter, in contrast to commonly used phenomenological 3N interactions.

  14. Self-Assembly of Hierarchical Chiral Nanostructures Based on Metal-Benzimidazole Interactions: Chiral Nanofibers, Nanotubes, and Microtubular Flowers.

    PubMed

    Zhou, Xiaoqin; Jin, Qingxian; Zhang, Li; Shen, Zhaocun; Jiang, Long; Liu, Minghua

    2016-09-01

    Controlled hierarchical self-assembly of synthetic molecules into chiral nanoarchitectures to mimic those biological chiral structures is of great importance. Here, a low-molecular-weight organogelator containing a benzimidazole moiety conjugated with an amphiphilic l-glutamic amide has been designed and its self-assembly into various hierarchical chiral nanostructures is investigated. Upon gel formation in organic solvents, 1D chiral nanostructure such as nanofiber and nanotube are obtained depending on the solvents. In the presence of transition and rare earth metal ions, hierarchical chiral nanostructures are formed. Specifically, the addition of TbCl3 , EuCl3 , and AgNO3 leads to nanofiber structures, while the addition of Cu(NO3 )2 , Tb(NO3 )3 , or Eu(NO3 )3 provides the microflower structures and microtubular flower structures, respectively. While Eu(III) and Tb(III)-containing microtubular flowers keep the chirality, the Cu(II)-coordinated microflowers lose chirality. More interestingly, the nanofibers formed by the gelator coordinated with Eu(III) or Tb(III) ions show not only the supramolecular chirality but also the circularly polarized luminescence. PMID:27248367

  15. Statistical uncertainties of a chiral interaction at next-to-next-to leading order

    SciTech Connect

    Ekström, A.; Carlsson, B. D.; Wendt, K. A.; Forssén, Christian; Jensen, M. Hjorth; Machleidt, R.; Wild, S. M.

    2015-02-05

    In this paper, we have quantified the statistical uncertainties of the low-energy coupling-constants (LECs) of an optimized nucleon–nucleon interaction from chiral effective field theory at next-to-next-to-leading order. Finally, in addition, we have propagated the impact of the uncertainties of the LECs to two-nucleon scattering phase shifts, effective range parameters, and deuteron observables.

  16. Interaction between ketopantolactone and chirally modified Pt investigated by attenuated total reflection IR concentration modulation spectroscopy.

    PubMed

    Bonalumi, Norberto; Bürgi, Thomas; Baiker, Alfons

    2003-11-01

    The combination of ATR-IR and modulation spectroscopy allowed for the study of the interaction of ketopantolactone with Pt/Al2O3 films chirally modified by cinchonidine under hydrogenation conditions. The spectra reveal a significant influence of ketopantolactone on the adsorption of the modifier and indicate a N-H-O hydrogen bond between modifier and reactant. The latter was corroborated by a comparative study with N-methyl cinchonidine chloride modified Pt/Al2O3.

  17. The chiral S = -1 meson-baryon interaction with new constraints on the NLO contributions

    NASA Astrophysics Data System (ADS)

    Ramos, A.; Feijoo, A.; Magas, V. K.

    2016-10-01

    We present a study of the S = - 1 meson-baryon interaction, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the model have been fitted to a large set of experimental scattering data in different two-body channels, to threshold branching ratios, and to the precise SIDDHARTA value of the energy shift and width of kaonic hidrogen. In contrast to other groups, we have taken into consideration the K- p →K+Ξ- ,K0Ξ0 reaction data, since we found in a previous work to be especially sensitive to the NLO parameters of the chiral Lagrangian. In the present work we also include the Born terms, which usually have very little effect, and find them to be non-negligible in the K- p → KΞ channels, correspondingly causing significant modifications to the NLO parameters. We furthermore show that the importance of the Born terms becomes more visible in the isospin projected amplitudes of the K- p → KΞ reactions. The measurement of processes that filter single isospin components, like the KL0 p →K+Ξ0 reaction that could be measured at the proposed secondary KL0 beam at Jlab, would put valuable constraints on the chiral models describing the meson-baryon interaction in the S = - 1 sector.

  18. Chiral magnetism and spontaneous spin Hall effect of interacting Bose superfluids.

    PubMed

    Li, Xiaopeng; Natu, Stefan S; Paramekanti, Arun; Das Sarma, S

    2014-01-01

    Recent experiments on ultracold atoms in optical lattices have synthesized a variety of tunable bands with degenerate double-well structures in momentum space. Such degeneracies in the single-particle spectrum strongly enhance quantum fluctuations, and often lead to exotic many-body ground states. Here we consider weakly interacting spinor Bose gases in such bands, and discover a universal quantum 'order by disorder' phenomenon which selects a novel superfluid with chiral spin order displaying remarkable properties such as spontaneous spin Hall effect and momentum space antiferromagnetism. For bosons in the excited Dirac band of a hexagonal lattice, such a state supports staggered spin loop currents in real space. We show that Bloch oscillations provide a powerful dynamical route to quantum state preparation of such a chiral spin superfluid. Our predictions can be readily tested in spin-resolved time-of-flight experiments.

  19. Capacitance-modulated transistor detects odorant binding protein chiral interactions

    PubMed Central

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand–protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein–ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters. PMID:25591754

  20. Capacitance-modulated transistor detects odorant binding protein chiral interactions.

    PubMed

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters. PMID:25591754

  1. Chirally selective, intramolecular interaction observed in an aminoacyl adenylate anhydride

    NASA Technical Reports Server (NTRS)

    Lacey, J. C., Jr.; Hall, L. M.; Mullins, D. W., Jr.; Watkins, C. L.

    1985-01-01

    The interaction between amino acids and nucleotide bases is studied. The proton NMR spectrum of N-acetylphenylalanyl-AMP-anhydride is analyzed H8 and H2 signals, two upfield signals of equal size, and five phenylalanine ring proton signals are observed in the spectrum; the upfield movement of the proton and the racemization of the N-acetyl L-phenylalanine material are examined. The differences in the position of the signals due to the diastereoisomers are investigated. The separation of the D and L amino acyl adenylates using HPLC is described. H-1 NMR spectra of the isomers are examined in order to determine which isomer displays the strongest interaction between the phenyl ring and the adenine ring. The spectra reveal that the L isomer shows the highest upfield change of both H8 and H2 signals. It is noted that the phenyl ring lies over C2 of the adenine ring with the phenyl meta and para protons extended past the adenine ring and the phenyl ortho protons.

  2. Capacitance-modulated transistor detects odorant binding protein chiral interactions

    NASA Astrophysics Data System (ADS)

    Mulla, Mohammad Yusuf; Tuccori, Elena; Magliulo, Maria; Lattanzi, Gianluca; Palazzo, Gerardo; Persaud, Krishna; Torsi, Luisa

    2015-01-01

    Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters.

  3. Stereoselectivity of chiral drug transport: a focus on enantiomer-transporter interaction.

    PubMed

    Zhou, Quan; Yu, Lu-Shan; Zeng, Su

    2014-08-01

    Drug transporters and drug metabolism enzymes govern drug absorption, distribution, metabolism and elimination. Many literature works presenting important aspects related to stereochemistry of drug metabolism are available. However, there is very little literature on stereoselectivity of chiral drug transport and enantiomer-transporter interaction. In recent years, the experimental research within this field showed good momentum. Herein, an up-to-date review on this topic was presented. Breast Cancer Resistance Protein (BCRP), Multidrug Resistance Proteins (MRP), P-glycoprotein (P-gp), Organic Anion Transporters (OATs), Organic Anion Transporting Polypeptides (OATPs), Organic Cation Transporters (OCTs), Peptide Transport Proteins (PepTs), Human Proton-Coupled Folate Transporter (PCFT) and Multidrug and Toxic Extrusion Proteins (MATEs), have been reported to exhibit either positive or negative enantio-selective substrate recognition. The approaches utilized to study chirality in enantiomer-transporter interaction include inhibition experiments of specific transporters in cell models (e.g. Caco-2 cells), transport study using drug resistance cell lines or transgenic cell lines expressing transporters in wild type or variant, the use of transporter knockout mice, pharmacokinetics association of single nucleotide polymorphism in transporters, pharmacokinetic interaction study of racemate in the presence of specific transporter inhibitor or inducer, molecule cellular membrane affinity chromatography and pharmacophore modeling. Enantiomer-enantiomer interactions exist in chiral transport. The strength and/or enantiomeric preference of stereoselectivity may be species or tissue-specific, concentration-dependent and transporter family member-dependent. Modulation of specific drug transporter by pure enantiomers might exhibit opposite stereoselectivity. Further studies with integrated approaches will open up new horizons in stereochemistry of pharmacokinetics. PMID:24796860

  4. Exploring Enantiospecific Ligand-Protein Interactions Using Cellular Membrane Affinity Chromatography: Chiral Recognition as a Dynamic Process

    PubMed Central

    Jozwiak, Krzysztof; Moaddel, Ruin; Ravichandran, Sarangan; Plazinska, Anita; Kozak, Joanna; Patel, Sharvil; Yamaguchi, Rika; Wainer, Irving

    2008-01-01

    The chiral recognition mechanisms responsible for the enantioselective binding on the α3β4 nicotinic acetyl choline receptor (α3β4 nAChR) and human organic cation transporter 1 (hOCT1) have been reviewed. The results indicate that chiral recognition on the α3β4 nAChR is a process involving initial tethering of dextromethorphan and levomethorphan at hydrophobic pockets within the central lumen followed by hydrogen bonding interactions favoring dextromethorphan. The second step is the defining enantioselective step. Studies with the hOCT1 indentified four binding sites within the transporter that participated in chiral recognition. Each of the enantiomers of the compounds used in the study interacted with three of these sites, while (R)-verapamil interacted with all four. Chiral recognition arose from the conformational adjustments required to produce optimum interactions. With respect to the prevailing interaction-based models, the data suggest that chiral recognition is a dynamic process and that the static point-based models should be amended to reflect this. PMID:18723411

  5. Uncertainty quantification for proton-proton fusion in chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Acharya, B.; Carlsson, B. D.; Ekström, A.; Forssén, C.; Platter, L.

    2016-09-01

    We compute the S-factor of the proton-proton (pp) fusion reaction using chiral effective field theory (χEFT) up to next-to-next-to-leading order (NNLO) and perform a rigorous uncertainty analysis of the results. We quantify the uncertainties due to (i) the computational method used to compute the pp cross section in momentum space, (ii) the statistical uncertainties in the low-energy coupling constants of χEFT, (iii) the systematic uncertainty due to the χEFT cutoff, and (iv) systematic variations in the database used to calibrate the nucleon-nucleon interaction. We also examine the robustness of the polynomial extrapolation procedure, which is commonly used to extract the threshold S-factor and its energy-derivatives. By performing a statistical analysis of the polynomial fit of the energy-dependent S-factor at several different energy intervals, we eliminate a systematic uncertainty that can arise from the choice of the fit interval in our calculations. In addition, we explore the statistical correlations between the S-factor and few-nucleon observables such as the binding energies and point-proton radii of 2,3H and 3He as well as the D-state probability and quadrupole moment of 2H, and the β-decay of 3H. We find that, with the state-of-the-art optimization of the nuclear Hamiltonian, the statistical uncertainty in the threshold S-factor cannot be reduced beyond 0.7%.

  6. Constraints on Neutron Star Radii Based on Chiral Effective Field Theory Interactions

    SciTech Connect

    Hebeler, K.; Lattimer, J. M.; Pethick, C. J.; Schwenk, A.

    2010-10-15

    We show that microscopic calculations based on chiral effective field theory interactions constrain the properties of neutron-rich matter below nuclear densities to a much higher degree than is reflected in commonly used equations of state. Combined with observed neutron star masses, our results lead to a radius R=9.7-13.9 km for a 1.4M{sub {center_dot}} star, where the theoretical range is due, in about equal amounts, to uncertainties in many-body forces and to the extrapolation to high densities.

  7. Nuclear pairing from bare interaction: Two and three-body chiral forces

    SciTech Connect

    Finelli, Paolo

    2012-10-20

    In a recent paper the {sup 1}S{sub 0} pairing gap in isospin-symmetric nuclear matter and finite nuclei has been investigated starting from the chiral nucleon-nucleon potential at the N{sup 3}LO order in the two-body sector and the N{sup 2}LO order in the three-body sector. To include realistic nuclear forces in RHB (Relativistic Hartree Bolgoliubov) calculations we relied on a separable representation of the pairing interaction. In this paper we would like to show recent results concerning isotonic chains with N= 28,50,82.

  8. Variational Calculation of K-pp with Chiral SU(3)-BASED bar KN Interaction

    NASA Astrophysics Data System (ADS)

    Doté, A.; Hyodo, T.; Weise, W.

    The prototype of a bar K nuclear cluster, K-pp, has been investigated using effective bar KN potentials based on chiral SU(3) dynamics. Variational calculation shows a bound state solution with shallow binding energy B(K-pp) = 20 ± 3 MeV and broad mesonic decay width Γ (bar KNN -> π YN) = 40 - 70 {MeV}. The bar KN(I = 0) pair in the K-pp system exhibits a similar structure as the Λ(1405). We have also estimated the dispersive correction, p-wave bar KN interaction, and two-nucleon absorption width.

  9. Variational Calculation of K-pp with Chiral SU(3)-BASED bar KN Interaction

    NASA Astrophysics Data System (ADS)

    Doté, A.; Hyodo, T.; Weise, W.

    2010-10-01

    The prototype of a bar K nuclear cluster, K-pp, has been investigated using effective bar KN potentials based on chiral SU(3) dynamics. Variational calculation shows a bound state solution with shallow binding energy B(K-pp) = 20 ± 3 MeV and broad mesonic decay width Γ (bar KNN -> π YN) = 40 - 70 {MeV}. The bar KN(I = 0) pair in the K-pp system exhibits a similar structure as the Λ(1405). We have also estimated the dispersive correction, p-wave bar KN interaction, and two-nucleon absorption width.

  10. Chiral phase from three-spin interactions in an optical lattice

    SciTech Connect

    D'Cruz, Christian; Pachos, Jiannis K.

    2005-10-15

    A spin-1/2 chain model that includes three-spin interactions can effectively describe the dynamics of two species of bosons trapped in an optical lattice with a triangular-ladder configuration. A perturbative theoretical approach and numerical study of its ground state is performed that reveals a rich variety of phases and criticalities. We identify phases with periodicity one, two, or three, as well as critical points that belong in the same universality class as the Ising or the three-state Potts model. We establish a range of parameters, corresponding to a large degeneracy present between phases with period 2 and 3, that nests a gapless incommensurate chiral phase.

  11. Nuclear matter saturation with chiral three-nucleon interactions fitted to light nuclei properties

    NASA Astrophysics Data System (ADS)

    Logoteta, Domenico; Bombaci, Ignazio; Kievsky, Alejandro

    2016-07-01

    The energy per particle of symmetric nuclear matter and pure neutron matter is calculated using the many-body Brueckner-Hartree-Fock approach and employing the Chiral Next-to-next-to-next-to leading order (N3LO) nucleon-nucleon (NN) potential, supplemented with various parametrizations of the Chiral Next-to-next-to leading order (N2LO) three-nucleon interaction. Such combination is able to reproduce several observables of the physics of light nuclei for suitable choices of the parameters entering in the three-nucleon interaction. We find that some of these parametrizations provide a satisfactory saturation point of symmetric nuclear matter and values of the symmetry energy and its slope parameter L in very good agreement with those extracted from various nuclear experimental data. Thus, our results represent a significant step toward a unified description of few- and many-body nuclear systems starting from two- and three-nucleon interactions based on the symmetries of QCD.

  12. Enhanced Flight Termination System (EFTS): Flight Demonstration and Results

    NASA Technical Reports Server (NTRS)

    Tow, David; Arce, Dennis

    2008-01-01

    The Enhanced Flight Termination System (EFTS) program was initiated and propelled due to the inadvertent terminations of Global Hawk and the Strategic Target System and the NASA Inspector General's assessment letter and recommendations regarding the exploration of low-cost, lightweight space COMSEC for FTS. Additionally, the standard analog and high alphabet systems most commonly used in FTS are secure, but not encrypted. A study group was initiated to select and document a robust, affordable, reliable technology that provides encrypted FTS capability. A flight demonstration was conducted to gain experience using EFTS in an operational environment, provide confidence in the use of the EFTS components, integrate EFTS into an existing range infrastructure to demonstrate the scalability of system components, to provide a command controller that generated the EFTS waveform using an existing range infrastructure, and to provide a report documenting the results of the demonstration. The primary goal of the demonstration was to obtain operational experience with EFTS. Areas of operational experience include: mission planning, pre-flight configuration and testing, mission monitoring and recording, vehicle termination, developing mission procedures. and post mission data reduction and other post mission activities. An Advanced Medium-Range Air-to-Air Missile (AMRAAM) was selected to support the EFTS demonstration due to interest in future use of EFTS by the AMRAAM program, familiarity of EFTS by range personnel, and the availability of existing operational environment to support EFTS testing with available program funding. For demonstration purposes, the AMRAAM was successfully terminated using an EFTS receiver and successfully demonstrating EFTS. The EFTS monitoring software with spectrum analyzer and digital graphical display of aircraft, missile, and target were also demonstrated.

  13. Synthesis, characterization, DNA/BSA interactions and anticancer activity of achiral and chiral copper complexes.

    PubMed

    Zhou, Xue-Quan; Sun, Qian; Jiang, Lin; Li, Si-Tong; Gu, Wen; Tian, Jin-Lei; Liu, Xin; Yan, Shi-Ping

    2015-05-28

    Six novel copper(ii) complexes of [CuCl]ClO4 (), [Cu(acac)]PF6 (), [CuCl]2(PF6)2 (), [CuCl]2(PF6)2 (), [Cu(acac)]PF6 () and [Cu(acac)]PF6 (), ( = 1-naphthyl-N,N-[bis(2-pyridyl)methyl]amine, = R/S-1-naphthyl-N,N-[bis(2-pyridyl)methyl]ethanamine, acac = diacetone) were synthesized to serve as artificial nucleases. All complexes were structurally characterized using X-ray crystallography. The crystal structures showed the presence of distorted square-planar CuLCl (, and ) and distorted tetragonal-pyramidal CuL(acac) (, and ) geometry. The interaction of these complexes with calf thymus DNA (CT-DNA) was researched by means of several spectroscopy methods, which indicated that the complexes were bound to CT-DNA by an intercalation binding mode. DNA cleavage experiments revealed that the complexes exhibited remarkable DNA cleavage activities in the presence of H2O2, and single oxygen ((1)O2) or hydroxyl radicals may serve as the major cleavage active species. In particular, the in vitro cytotoxicity of the complexes on four human cancer cell lines (HeLa, MCF-7, Bel-7404 and HepG-2) demonstrated that the six compounds had broad-spectrum anti-cancer activity with low IC50 values. The stronger cytotoxicity and DNA cleavage activity of the chiral enantiomers compared with chiral analogues verified the influence of chirality on the antitumor activity of complexes. Meanwhile, the protein binding ability was revealed by quenching of tryptophan emission with the addition of complexes using BSA as a model protein. The results indicated that the quenching mechanism of BSA by the complexes was a static process.

  14. Three-Nucleon Low-Energy Constants From The Consistency Of Interactions And Currents In Chiral Effective Field Theory

    SciTech Connect

    Gazit, D; Quaglioni, S; Navratil, P

    2008-12-18

    The chiral low-energy constants cD and cE are constrained by means of accurate ab initio calculations of the A = 3 binding energies and, for the first time, of the triton {beta} decay. We demonstrate that these low-energy observables allow a robust determination of the two undetermined constants. The consistency of the interactions and currents in chiral effective field theory is key to this remarkable result. The two- plus three-nucleon interactions from chiral effective field theory defined by properties of the A = 2 system and the present determination of c{sub D} and c{sub E} are successful in predicting properties of the A = 3, and 4 systems.

  15. EFT-1 Heatshield Aerothermal Environment Reconstruction

    NASA Technical Reports Server (NTRS)

    Oliver, A. Brandon; Amar, Adam J.; Droba, Justin; Lessard, Victor; Mahzari, Milad

    2016-01-01

    The EFT-1 Avcoat heatshield was instrumented with 34 plugs containing multiple thermocouples in-depth with an objective being to measure the flight aerothermal environment. This paper presents a discussion of the instrumentation and the techniques used to reconstruct the heating environment from the measured in-depth temperatures. The inverse heat transfer problem algorithms, models and assumptions will be outlined, and available results will be presented.

  16. Nuclear-matter equation of state with consistent two- and three-body perturbative chiral interactions

    NASA Astrophysics Data System (ADS)

    Coraggio, L.; Holt, J. W.; Itaco, N.; Machleidt, R.; Marcucci, L. E.; Sammarruca, F.

    2014-04-01

    We compute the energy per particle of infinite symmetric nuclear matter from chiral NLO3 (next-to-next-to-next-to-leading order) two-body potentials plus NLO2 three-body forces. The low-energy constants of the chiral three-nucleon force that cannot be constrained by two-body observables are fitted to reproduce the triton binding energy and the H3-He3 Gamow-Teller transition matrix element. In this way, the saturation properties of nuclear matter are reproduced in a parameter-free approach. The equation of state is computed up to third order in many-body perturbation theory, with special emphasis on the role of the third-order particle-hole diagram. The dependence of these results on the cutoff scale and regulator function is studied. We find that the inclusion of three-nucleon forces consistent with the applied two-nucleon interaction leads to a reduced dependence on the choice of the regulator only for lower values of the cutoff.

  17. Electromagnetic Currents and Magnetic Moments in $\\chi$EFT

    SciTech Connect

    Saori Pastore, Luca Girlanda, Rocco Schiavilla, Michele Viviani, Robert Wiringa

    2009-09-01

    A two-nucleon potential and consistent electromagnetic currents are derived in chiral effective field theory ($\\chi$EFT) at, respectively, $Q^{\\, 2}$ (or N$^2$LO) and $e\\, Q$ (or N$^3$LO), where $Q$ generically denotes the low-momentum scale and $e$ is the electric charge. Dimensional regularization is used to renormalize the pion-loop corrections. A simple expression is derived for the magnetic dipole ($M1$) operator associated with pion loops, consisting of two terms, one of which is determined, uniquely, by the isospin-dependent part of the two-pion-exchange potential. This decomposition is also carried out for the $M1$ operator arising from contact currents, in which the unique term is determined by the contact potential. Finally, the low-energy constants (LEC's) entering the N$^2$LO potential are fixed by fits to the $np$ S- and P-wave phase shifts up to 100 MeV lab energies. Three additional LEC's are needed to completely specify the $M1$ operator at N$^3$L

  18. Intershell Interaction in a Double Wall Carbon Nanotube with Determined Chiral Indices under a Torsional Strain

    NASA Astrophysics Data System (ADS)

    Lin, Letian; Cui, Taoran; Washburn, Sean; Qin, Lu-Chang

    2011-03-01

    We have used a double wall carbon nanotube to build a torsional pendulum. The nanotube worked as a torsional bearing for a metal block. An external electric field was used to rotate the metal block to cause a fully elastic torsional deformation on the nanotube. Nano-beam electron diffraction patterns were taken before and while the nanotube was twisted. By analysis of the shift of the diffraction patterns, we were able to determine the nanotube chiral indices and measure the inner-shell torisonal responses to the torsional stress applied on the outer-shell. The inter-shell interactions and nanotube shear modulus were also calculated and discussed in connection to the theoretical estimations.

  19. Toroidal Interaction and Propeller Chirality of Hexaarylbenzenes. Dynamic Domino Inversion Revealed by Combined Experimental and Theoretical Circular Dichroism Studies.

    PubMed

    Kosaka, Tomoyo; Inoue, Yoshihisa; Mori, Tadashi

    2016-03-01

    Hexaarylbenzenes (HABs) have greatly attracted much attention due to their unique propeller-shaped structure and potential application in materials science, such as liquid crystals, molecular capsules/rotors, redox materials, nonlinear optical materials, as well as molecular wires. Less attention has however been paid to their propeller chirality. By introducing small point-chiral group(s) at the periphery of HABs, propeller chirality was effectively induced, provoking strong Cotton effects in the circular dichroism (CD) spectrum. Temperature and solvent polarity manipulate the dynamics of propeller inversion in solution. As such, whizzing toroids become more substantial in polar solvents and at an elevated temperature, where radial aromatic rings (propeller blades) prefer orthogonal alignment against the central benzene ring (C6 core), maximizing toroidal interactions.

  20. Chiral-glass transition in a diluted dipolar-interaction Heisenberg system

    NASA Astrophysics Data System (ADS)

    Zhang, Kai-Cheng; Liu, Gui-Bin; Zhu, Yan

    2011-05-01

    Recently, numerical simulations reveal that a spin-glass transition can occur in the three-dimensional diluted dipolar system. By defining the chirality of triple spins in a diluted dipolar Heisenberg spin glass, we study the chiral ordering in the system using parallel tempering algorithm and heat bath method. The finite-size scaling analysis reveals that the system undergoes a chiral-glass transition at finite temperature.

  1. Antikaon-nucleon interaction and Λ(1405) in chiral SU(3) dynamics

    NASA Astrophysics Data System (ADS)

    Kamiya, Yuki; Miyahara, Kenta; Ohnishi, Shota; Ikeda, Yoichi; Hyodo, Tetsuo; Oset, Eulogio; Weise, Wolfram

    2016-10-01

    The properties of the Λ (1405) resonance are key ingredients for determining the antikaon-nucleon interaction in strangeness nuclear physics, and the novel internal structure of the Λ (1405) is of great interest in hadron physics, as a prototype case of a baryon that does not fit into the simple three-quark picture. We show that a quantitative description of the antikaon-nucleon interaction with the Λ (1405) is achieved in the framework of chiral SU(3) dynamics, with the help of recent experimental progress. Further constraints on the K bar N subthreshold interaction are provided by analyzing πΣ spectra in various processes, such as the K- d → πΣn reaction and the Λc → ππΣ decay. The structure of the Λ (1405) is found to be dominated by an antikaon-nucleon molecular configuration, based on its wavefunction derived from a realistic K bar N potential and the compositeness criteria from a model-independent weak-binding relation.

  2. On the effect of a radiation field in modifying the intermolecular interaction between two chiral molecules

    SciTech Connect

    Salam, A.

    2006-01-07

    The change in the mutual energy of interaction between a pair of chiral molecules coupled via the exchange of a single virtual photon and in the presence of an electromagnetic field is calculated using nonrelativistic quantum electrodynamics. The particular viewpoint adopted is one that has an intuitive physical appeal and resembles a classical treatment. It involves the coupling of electric and magnetic dipole moments induced at each center by the incident radiation field to the resonant dipole-dipole interaction tensor. The energy shift is evaluated for fixed as well as random orientations of the molecular pair with respect to the direction of propagation of the field. A complete polarization analysis is carried out for the former situation by examining the effect of incident radiation that is linearly or circularly polarized and traveling in a direction that is parallel or perpendicular to the intermolecular distance vector. After tumble averaging, all polarization dependence of the energy shift vanishes. In both cases the interaction energy is directly proportional to the irradiance of the applied field, and is discriminatory, changing sign when one optically active species is replaced by its enantiomer. The asymptotic behavior of the energy shift at the limits of large and small separations is also studied.

  3. 48 CFR 32.1109 - EFT information submitted by offerors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false EFT information submitted by offerors. 32.1109 Section 32.1109 Federal Acquisition Regulations System FEDERAL ACQUISITION... information submitted by offerors. If offerors are required to submit EFT information prior to award,...

  4. 48 CFR 32.1109 - EFT information submitted by offerors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false EFT information submitted by offerors. 32.1109 Section 32.1109 Federal Acquisition Regulations System FEDERAL ACQUISITION... information submitted by offerors. If offerors are required to submit EFT information prior to award,...

  5. 48 CFR 32.1109 - EFT information submitted by offerors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false EFT information submitted by offerors. 32.1109 Section 32.1109 Federal Acquisition Regulations System FEDERAL ACQUISITION... information submitted by offerors. If offerors are required to submit EFT information prior to award,...

  6. 48 CFR 32.1109 - EFT information submitted by offerors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false EFT information submitted by offerors. 32.1109 Section 32.1109 Federal Acquisition Regulations System FEDERAL ACQUISITION... information submitted by offerors. If offerors are required to submit EFT information prior to award,...

  7. Spectroscopic investigations of the chiral interactions of metolachlor and its (S)-isomer with lipase and phosphatase.

    PubMed

    Wen, Yue Z; Yuan, Yu L; Chen, Hui; Wang, He L; Liu, Hui J; Kang, Xiao D; Fu, Liu S

    2010-04-01

    Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] is a chiral acetanilide herbicide. We investigated its enantioselective interactions, and that of its (S)-isomer, with Penicillium expansum alkaline lipase and phosphatase. UV differential spectroscopy and fluorescence spectrophotometry studies were conducted in phosphate buffered solution at pH 7. Chiral differences in the UV absorption and fluorescence spectra of lipase and phosphatase with metolachlor and its (S)-isomer were detected. The results showed that the interactions of metolachlor and its (S)-isomer with lipase and phosphatase occur statically through complex formation, and enantioselectivity was clearly observed. In addition, both UV absorption and fluorescence spectrophotometry showed that the (S)-isomer interacted more strongly with lipase and phosphatase than metolachlor. PMID:20390958

  8. Spectroscopic investigations of the chiral interactions of metolachlor and its (S)-isomer with lipase and phosphatase.

    PubMed

    Wen, Yue Z; Yuan, Yu L; Chen, Hui; Wang, He L; Liu, Hui J; Kang, Xiao D; Fu, Liu S

    2010-04-01

    Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] is a chiral acetanilide herbicide. We investigated its enantioselective interactions, and that of its (S)-isomer, with Penicillium expansum alkaline lipase and phosphatase. UV differential spectroscopy and fluorescence spectrophotometry studies were conducted in phosphate buffered solution at pH 7. Chiral differences in the UV absorption and fluorescence spectra of lipase and phosphatase with metolachlor and its (S)-isomer were detected. The results showed that the interactions of metolachlor and its (S)-isomer with lipase and phosphatase occur statically through complex formation, and enantioselectivity was clearly observed. In addition, both UV absorption and fluorescence spectrophotometry showed that the (S)-isomer interacted more strongly with lipase and phosphatase than metolachlor.

  9. ENANTIOMER-SPECIFIC EFFECTS OF CHIRAL POLLUTANTS

    EPA Science Inventory

    Enantiomers, the mirror image isomers of chiral pollutants, are known to be selective in their interaction with other chiral molecules, including enzymes and other biochemicals. Considerable research has shown, for example, that chiral pesticides are degraded selectively by micr...

  10. Chiral effective field theory analysis of hadronic parity violation in few-nucleon systems

    NASA Astrophysics Data System (ADS)

    Viviani, M.; Baroni, A.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Schiavilla, R.

    2014-06-01

    Background: Weak interactions between quarks induce a parity-violating (PV) component in the nucleon-nucleon potential, whose effects are currently being studied in a number of experiments involving few-nucleon systems. In the present work, we reconsider the derivation of this PV component within a chiral effective field theory (χEFT) framework. Purpose: The objectives of the present work are twofold. The first is to perform a detailed analysis of the PV nucleon-nucleon potential up to next-to-next-to-leading (N2LO) order in the chiral expansion, in particular, by determining the number of independent low-energy constants (LECs) at N2LO. The second objective is to investigate PV effects in a number of few-nucleon observables, including the p⃗-p longitudinal asymmetry, the neutron spin rotation in n⃗-p and n⃗-d scattering, and the longitudinal asymmetry in the 3He(n⃗,p)3H charge-exchange reaction. Methods: The χEFT PV potential includes one-pion-exchange, two-pion-exchange, and contact terms as well as 1/M (M being the nucleon mass) nonstatic corrections. Dimensional regularization is used to renormalize pion loops. The wave functions for the A =2-4 nuclei are obtained by using strong two- and three-body potentials also derived, for consistency, from χEFT. In the case of the A =3-4 systems, the wave functions are computed by expanding on a hyperspherical harmonics functions basis. Results: We find that the PV potential at N2LO depends on six LECs: the pion-nucleon PV coupling constant hπ1 and five parameters multiplying contact interactions. An estimate for the range of values of the various LECs is provided by using available experimental data, and these values are used to obtain predictions for the other PV observables. Conclusions: The χEFT approach provides a very satisfactory framework to analyze PV effects in few-nucleon systems.

  11. Chiral effective field theory analysis of hadronic parity violation in few-nucleon systems

    SciTech Connect

    Viviani, M.; Baroni, A.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Schiavilla, R.

    2014-06-18

    Weak interactions between quarks induce a parity-violating (PV) component in the nucleon-nucleon potential, whose effects are currently being studied in a number of experiments involving few-nucleon systems. In the present work, we reconsider the derivation of this PV component within a chiral effective field theory (${\\chi }$EFT) framework. Purpose: The objectives of the present work are twofold. The first is to perform a detailed analysis of the PV nucleon-nucleon potential up to next-to-next-to-leading (N2LO) order in the chiral expansion, in particular, by determining the number of independent low-energy constants (LECs) at N2LO. The second objective is to investigate PV effects in a number of few-nucleon observables, including the $\\vec{p}$-p longitudinal asymmetry, the neutron spin rotation in n-p and n-d scattering, and the longitudinal asymmetry in the 3He( $\\vec{n}$,p)3H charge-exchange reaction. Methods: The ${\\chi }$EFT PV potential includes one-pion-exchange, two-pion-exchange, and contact terms as well as 1/M (M being the nucleon mass) nonstatic corrections. Dimensional regularization is used to renormalize pion loops. The wave functions for the A=2-4 nuclei are obtained by using strong two- and three-body potentials also derived, for consistency, from ${\\chi }$EFT. In the case of the A=3-4 systems, systems, the wave functions are computed by expanding on a hyperspherical harmonics functions basis. Results: We find that the PV potential at N2LO depends on six LECs: the pion-nucleon PV coupling constant h$1\\atop{π}$ and five parameters multiplying contact interactions. An estimate for the range of values of the various LECs is provided by using available experimental data, and these values are used to obtain predictions for the other PV observables. Conclusions: The ${\\chi }$EFT approach provides a very satisfactory framework to analyze PV effects in few-nucleon systems.

  12. Molecular model for chirality phenomena

    NASA Astrophysics Data System (ADS)

    Latinwo, Folarin; Stillinger, Frank H.; Debenedetti, Pablo G.

    2016-10-01

    Chirality is a hallmark feature for molecular recognition in biology and chemical physics. We present a three-dimensional continuum model for studying chirality phenomena in condensed phases using molecular simulations. Our model system is based upon a simple four-site molecule and incorporates non-trivial kinetic behavior, including the ability to switch chirality or racemize, as well as thermodynamics arising from an energetic preference for specific chiral interactions. In particular, we introduce a chiral renormalization parameter that can locally favor either homochiral or heterochiral configurations. Using this model, we explore a range of chirality-specific phenomena, including the kinetics of chiral inversion, the mechanism of spontaneous chiral symmetry breaking in the liquid, chirally driven liquid-liquid phase separation, and chiral crystal structures.

  13. Catalysis of dynamical chiral symmetry breaking by chiral chemical potential

    NASA Astrophysics Data System (ADS)

    Braguta, V. V.; Kotov, A. Yu.

    2016-05-01

    In this paper, we study the properties of media with chiral imbalance parametrized by chiral chemical potential. It is shown that depending on the strength of interaction between constituents in the media the chiral chemical potential either creates or enhances dynamical chiral symmetry breaking. Thus, the chiral chemical potential plays the role of the catalyst of dynamical chiral symmetry breaking. Physically, this effect results from the appearance of the Fermi surface and additional fermion states on this surface, which take part in dynamical chiral symmetry breaking. An interesting conclusion which can be drawn is that at sufficiently small temperature chiral plasma is unstable with respect to condensation of Cooper pairs and dynamical chiral symmetry breaking even for vanishingly small interactions between constituents.

  14. Three-Nucleon Low-Energy Constants from the Consistency of Interactions and Currents in Chiral Effective Field Theory

    SciTech Connect

    Gazit, Doron; Quaglioni, Sofia; Navratil, Petr

    2009-09-04

    The chiral low-energy constants c{sub D} and c{sub E} are constrained by means of accurate ab initio calculations of the A=3 binding energies and, for the first time, of the triton {beta} decay. We demonstrate that these low-energy observables allow a robust determination of the two undetermined constants, a result of the surprising fact that the determination of c{sub D} depends weakly on the short-range correlations in the wave functions. These two- plus three-nucleon interactions, originating in chiral effective field theory and constrained by properties of the A=2 system and the present determination of c{sub D} and c{sub E}, are successful in predicting properties of the A=3 and 4 systems.

  15. Three-nucleon low-energy constants from the consistency of interactions and currents in chiral effective field theory.

    PubMed

    Gazit, Doron; Quaglioni, Sofia; Navrátil, Petr

    2009-09-01

    The chiral low-energy constants c(D) and c(E) are constrained by means of accurate ab initio calculations of the A = 3 binding energies and, for the first time, of the triton beta decay. We demonstrate that these low-energy observables allow a robust determination of the two undetermined constants, a result of the surprising fact that the determination of c(D) depends weakly on the short-range correlations in the wave functions. These two- plus three-nucleon interactions, originating in chiral effective field theory and constrained by properties of the A = 2 system and the present determination of c(D) and c(E), are successful in predicting properties of the A = 3 and 4 systems.

  16. Advanced Command Destruct System (ACDS) Enhanced Flight Termination System (EFTS)

    NASA Technical Reports Server (NTRS)

    Tow, David K.

    2011-01-01

    This presentation provides information on the development, integration, and operational usage of the Enhanced Flight Termination System (EFTS) at NASA Dryden Flight Research Center and Air Force Flight Test Center. The presentation will describe the efforts completed to certify the system and acquire approval for operational usage, the efforts to integrate the system into the NASA Dryden existing flight termination infrastructure, and the operational support of aircraft with EFTS at Edwards AFB.

  17. Description and Evaluation of Chiral Interactive Sites on Bonded Cyclodextrin Stationary Phases for Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Beesley, Thomas E.

    Development of chiral separations has been essential to the drug discovery and development process. The solubility requirements for a number of methods and/or the mobile phase requirements for application of certain detection systems have opened up many opportunities for cyclodextrin-based CSPs for liquid chromatography. Even though a few chiral stationary phases cover a wide area of enantioselectivity, they do not meet the entire needs of the industry. Cyclodextrin phases offer some unique mechanisms and opportunities to resolve chiral separation problems especially in the aqueous reversed-phase and non-aqueous polar organic modes. This chapter addresses the need to understand the chiral stationary phase structure, the mechanisms at work, and the role mobile phase composition plays in driving those mechanisms to produce enantioselectivity. In addition, the development of certain derivatives has played an essential part in expanding that basic role for certain chiral separations. What these derivatives contribute in concert with the basic structure is a critical part of the understanding to the effective use of these phases. During this study it was determined that the role of steric hindrance has been vastly underestimated, both to the extent that it has occurred and to its effectiveness for obtaining enantioselectivity. References to the entire 20-year history of the cyclodextrin phase development and application literature up to this current date have been reviewed and incorporated.

  18. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    PubMed

    Werber, Liora; Preiss, Laura C; Landfester, Katharina; Muñoz-Espí, Rafael; Mastai, Yitzhak

    2015-09-01

    Chiral polymeric nanoparticles are of prime importance, mainly due to their enantioselective potential, for many applications such as catalysis and chiral separation in chromatography. In this article we report on the preparation of chiral polymeric nanoparticles by miniemulsion polymerization. In addition, we describe the use of isothermal titration calorimetry (ITC) to measure the chiral interactions and the energetics of the adsorption of enantiomers from aqueous solutions onto chiral polymeric nanoparticles. The characterization of chirality in nano-systems is a very challenging task; here, we demonstrate that ITC can be used to accurately determine the thermodynamic parameters associated with the chiral interactions of nanoparticles. The use of ITC to measure the energetics of chiral interactions and recognition at the surfaces of chiral nanoparticles can be applied to other nanoscale chiral systems and can provide further insight into the chiral discrimination processes of nanomaterials.

  19. Combined analysis of ferromagnetic materials using the Heisenberg Green functions and Ising EFT methods

    NASA Astrophysics Data System (ADS)

    Moujaes, Elie A.; Khater, A.; Abou Ghantous, M.

    2015-10-01

    Ferromagnetic phase diagrams were, for a long time, unsuccessfully determined theoretically, despite the important Callen's 1963 [21] theoretical model. A great variety of experimental data for the magnetization over the entire range of temperature defining the ordered phase compared well with an empirical formula recently determined by Kuz'min (2005) [22]. Nonetheless, the Ising effective field theory (EFT), which can be of enormous support to both methods, was never given attention. The present work intends to show how the Ising EFT technique, when combined with the Green functions in Callen's work, is able to reconcile theoretical work with experimental data. The ratio kTc / JZS(S + 1) plays an important role in finding values for the exchange parameter J, whose first-principles calculation, often depending on the package used, is not properly done. J can be determined for a variety of ferromagnetic materials represented by general spin systems S with a number of nearest neighbours Z and critical temperature Tc, even for models including a percolative feature, characteristic of diluted interactive systems. We demonstrate that EFT is capable of estimating a value of J, which can substitute the use of more complex theoretical models or the performance of ab initio/DFT calculations.

  20. Chiral Nanostructures from Helical Copolymer-Metal Complexes: Tunable Cation-π Interactions and Sergeants and Soldiers Effect.

    PubMed

    Arias, Sandra; Bergueiro, Julián; Freire, Félix; Quiñoá, Emilio; Riguera, Ricardo

    2016-01-13

    Poly(phenylacetylene) (PPA) copolymers containing (R)- or (S)-MPA as minor chiral pendant can be forced to selectively adopt the right- o left-handed helix, in the presence of small amounts of Na(+) or Ag(+) ("Sergeants and Soldiers Effect") by addition of a donor cosolvent. The helical sense depends exclusively on the chiral monomer/donor cosolvent ratio, and this allows a perfect on/off tuning of the helicity of the copolymer. When the amount of the donor cosolvent is low, the metal ion complex is stabilized by a cation-π interaction, which is selectively cleaved when the amount of cosolvent is higher. Macroscopically chiral nanospheres and nanotubes composed by helical copolymers with P or M helical sense are also described. Our results demonstrate that it is possible to obtain the two enantiomeric helical structures (P and M helicities) and the corresponding nanospheres and nanotubes from a single helical copolymer, by controlled activation/deactivation of the Sergeant and Soldiers Effect with a donor cosolvent. PMID:26578292

  1. Asymmetric hydrogenation on chirally modified Pt: origin of hydrogen in the N-H-O interaction between cinchonidine and ketone.

    PubMed

    Maeda, Nobutaka; Hungerbühler, Konrad; Baiker, Alfons

    2011-12-14

    An understanding of the chiral site-substrate interaction is a necessary prerequisite for the rational design and development of efficient heterogeneous asymmetric catalysts. For the enantioselective hydrogenation of α-ketoesters on cinchona-modified platinum, it has earlier been proposed that the crucial interaction is an N-H-O type hydrogen bonding between the quinuclidine N atom of cinchonidine and the α-carbonyl O atom of the substrate. The involved hydrogen atom has been proposed to originate either from protonation (in protic solvent) or from dissociatively adsorbed hydrogen (in aprotic solvent), but experimental evidence for the latter was lacking so far. In this study, in situ attenuated total reflection infrared spectroscopy combined with modulation excitation spectroscopy and phase sensitive detection provides clear evidence that in aprotic media, hydrogen dissociated on Pt is involved in the N-H-O interaction between the chiral modifier, cinchonidine, and the ketone. In the absence of Pt (pure alumina support), no such interaction occurs, indicating the crucial role of dissociated hydrogen in the formation of the diastereomeric transition complex.

  2. Incoherent neutrinoproduction of photons and pions in a chiral effective field theory for nuclei

    NASA Astrophysics Data System (ADS)

    Zhang, Xilin; Serot, Brian D.

    2012-09-01

    We study the incoherent neutrinoproduction of photons and pions with neutrino energy Eν⩽0.5GeV. These processes are relevant to the background analysis in neutrino-oscillation experiments [for example, MiniBooNE; A. A. Aquilar-Arevalo (MiniBooNE Collaboration), Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.100.032301 100, 032301 (2008)]. The calculations are carried out using a Lorentz-covariant effective field theory (EFT), which contains nucleons, pions, the Delta (1232) (Δ), isoscalar scalar (σ) and vector (ω) fields, and isovector vector (ρ) fields, and has SU(2)L⊗SU(2)R chiral symmetry realized nonlinearly. The contributions of one-body currents are studied in the local Fermi gas approximation. The current form factors are generated by meson dominance in the EFT Lagrangian. The conservation of the vector current and the partial conservation of the axial current are satisfied automatically, which is crucial for photon production. The Δ dynamics in nuclei, as a key component in the study, is explored. Introduced Δ-meson couplings explain the Δ spin-orbit coupling in nuclei, and this leads to interesting constraints on the theory. Meanwhile, a phenomenological approach is applied to parametrize the Δ width. To benchmark our approximations, we calculate the differential cross sections for quasielastic scattering and incoherent electroproduction of pions without a final-state interaction (FSI). The FSI can be ignored for photon production.

  3. Chiral symmetry and chiral-symmetry breaking

    SciTech Connect

    Peskin, M.E.

    1982-12-01

    These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)

  4. Chiral streamers

    SciTech Connect

    Zou, Dandan; Cao, Xin; Lu, Xinpei; Ostrikov, Kostya

    2015-10-15

    The interaction of time-varying electromagnetic fields and solid, liquid, and gaseous matter may lead to electrical breakdown phenomena through the excitation of ionization waves or streamers that control the dynamics of localized plasma propagation through the media. The streamers usually propagate along straight lines, either between random points in space or along a certain direction in a guided mode. Here, we report on a new type of plasma discharges with the regular helical propagation pattern driven by a pulsed dc voltage in nitrogen at sub-atmospheric-pressure conditions. The helical guided streamers, named chiral streamers or chi-streamers, are excited without any external magnetic fields, which commonly cause helical plasma motions. We also demonstrate a hybrid propagation mode involving the interchangeable chiral streamers and the straight-line propagating plasmas. High-speed, time-resolved optical imaging reveals that the chiral streamers and the hybrid patterns are made of spatially localized discrete plasma bullets, similar to the straight-line guided streamers. These results may enable effective control of propagation of confined plasmas and electromagnetic energy along pre-determined, potentially deterministic paths, which have important implications for the development of next-generation plasma-based radiation sources, communication devices, and medical treatments.

  5. Chiral manganese (IV) complexes derived from Schiff base ligands: Synthesis, characterization, in vitro cytotoxicity and DNA/BSA interaction.

    PubMed

    Li, Zhen; Niu, Meiju; Chang, Guoliang; Zhao, Changqiu

    2015-12-01

    Two new couples of chiral manganese (IV) complexes with Schiff-base ligands, Λ-[Mn(R-L(1))2]·2(CH3OH) (Λ-1) and Δ-[Mn(S-L(1))2]·2(CH3OH) (Δ-1), Λ-[Mn(R-L(2))2]·(H2O)2 (Λ-2) and Δ-[Mn(S-L(2))2]·(H2O)2 (Δ-2), {H2L(1)=(R/S)-(±)-1-[(1-hydroxymethyl-propylimino)-methyl]-naphthalen-2-ol, H2L(2)=(R/S)-(±)-1-[(1-Hydroxymethyl-2-phenyl-ethylimino)-methyl]-naphthalen-2-ol} have been synthesized, and fully characterized by elemental analyses, UV-Vis spectrum, circular dichroism spectrum, FT-IR spectrum, mass spectrum, and single crystal X-ray diffraction (SXRD). The interaction of the four chiral Mn (IV) complexes with CT-DNA and BSA were also investigated by various spectroscopic techniques (UV-visible, fluorescence spectroscopic). The results show that the Δ-complexes exhibit more efficient CT-DNA interaction with respect to the Λ-complexes. All the complexes could quench the intrinsic fluorescence of BSA by a static quenching process. In addition, the vitro cytotoxicity of these complexes toward four kinds of cancerous cell lines (A549, HeLa, HL-60, and Caco-2) was assayed by the MTT method, which exhibited to be selectively active against certain cell lines.

  6. Process research on Emotionally Focused Therapy (EFT) for couples: linking theory to practice.

    PubMed

    Greenman, Paul S; Johnson, Susan M

    2013-03-01

    The focus of this article is on the link among theory, process, and outcome in the practice of Emotionally Focused Therapy (EFT) for couples. We describe the EFT model of change and the EFT perspective on adult love as the reflection of underlying attachment processes. We outline the manner in which theory and research inform EFT interventions. This leads into a detailed review of the literature on the processes of change in EFT. We highlight the client responses and therapist operations that have emerged from process research and their relation to treatment outcomes. We discuss the implications of this body of research for clinical practice and training.

  7. Chirality-related interactions and a mirror symmetry violation in handed nano structures

    SciTech Connect

    Gabuda, S. P.; Kozlova, S. G.

    2014-07-28

    Hindering of inversion transitions and a violation of mirror symmetry of the right- and left-handed configurations of diazabizyclooctane (dabco, N{sub 2}C{sub 6}H{sub 12}) enantiomers has been studied with low-temperature adiabatic calorimetry. The dabco molecules were sandwiched in a high-porous layered structure of a metal organic framework (MOF) compound. We show from the data of low-temperature adiabatic calorimetry and {sup 1}H NMR spin relaxation method that hindering of inversion transitions of dabco molecules cannot be associated with the influence of the intracrystalline self-consistent molecular field as a continuously monitoring environment within the quantum Zeno effect. In addition, lack of another manifestation of this effect associated with the collisional suppression of the inversion transitions in MOF samples impregnated by helium has been shown. These results lead to the conclusion that chiral polarization is related to the fundamental effect of parity nonconservation.

  8. Strangeness S = -2 baryon-baryon interaction at next-to-leading order in chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Haidenbauer, J.; Meißner, Ulf-G.; Petschauer, S.

    2016-10-01

    The strangeness S = - 2 baryon-baryon interaction is studied in chiral effective field theory up to next-to-leading order. The potential at this order consists of contributions from one- and two-pseudoscalar-meson exchange diagrams and from four-baryon contact terms without and with two derivatives. SU(3) flavor symmetry is imposed for constructing the interaction in the S = - 2 sector. Specifically, the couplings of the pseudoscalar mesons to the baryons are fixed by SU(3) symmetry and, in general, also the contact terms are related via SU(3) symmetry to those determined in a previous study of the S = - 1 hyperon-nucleon interaction. The explicit SU(3) symmetry breaking due to the physical masses of the pseudoscalar mesons (π, K, η) is taken into account. It is argued that the ΞN interaction has to be relatively weak to be in accordance with available experimental constraints. In particular, the published values and upper bounds for the Ξ- p elastic and inelastic cross sections apparently rule out a somewhat stronger attractive ΞN force and, specifically, disfavor any near-threshold deuteron-like bound states in that system.

  9. Investigation of the interaction between a novel unnatural chiral ligand and reactant on palladium for asymmetric hydrogenation.

    PubMed

    Jeon, Eun Hee; Yang, Sena; Kang, Sung Ho; Kim, Sehun; Lee, Hangil

    2015-07-21

    We report about the mechanistic studies of the reaction between a newly synthesized (S)-2-((R)-3H-dinaphtho[2,1-c:1',2'-e]azepin-4(5H)-yl)-2-phenylethanol based on the binaphthyl skeleton and (E)-2-methyl-5-phenylpent-2-enoic acid for the asymmetric hydrogenation of α,β-unsaturated acids with heterogeneous palladium catalysts. The specific interactions between the chiral ligand and reactant were investigated in solution with palladium nanoparticles, as well as under ultrahigh vacuum (UHV) conditions on the palladium metal surface in the absence of hydrogen. The reactions were explored using nuclear magnetic resonance (NMR) spectroscopy, scanning tunneling microscopy (STM), and high-resolution photoemission spectroscopy (HRPES) combined with density functional theory (DFT) calculations. A NMR study identified the interaction between both molecules with palladium nanoparticles in solution. In addition, STM and HRPES studies revealed the spatial distribution and configuration of both compounds on the palladium metal surface under UHV conditions. The theoretical results support the experimental results with respect to the interaction energy value. It was found that the reaction between the ligand and reactant occurs with hydrogen bonding on palladium surface, simultaneously. The present study provides mechanistic details of the asymmetric hydrogenation reaction, which bears a correlation between the ligand, reactant, and catalyst during the reaction.

  10. DNA-protein interactions as the source of large-length-scale chirality evident in the liquid crystal behavior of filamentous bacteriophages.

    PubMed

    Tomar, Sonit; Green, Mark M; Day, Loren A

    2007-03-21

    Although all filamentous phages are constructed of chiral components, this study of eight of these phages (fd, IKe, I(2)2, X-2, Pf1, Pf3, tf-1, and X) shows that some form nematic liquid crystals, which are apparently oblivious to the chirality of the components, while others form cholesteric liquid crystals revealing a type of structural chirality not normally encountered. Additions of dopants that interact with the DNA or protein components of the viruses change the liquid crystal properties of seven of the phages. In these seven, DNA-capsid symmetry differences do not allow strict structural equivalency among the protein subunits. The polymorphism arising from this nonequivalency is proposed here to give rise to coiling of the filaments, a large-length-scale chirality that is responsible for forming cholesteric liquid crystal phases. Only one phage of those studied here, Pf1, which is distinguished from the others in its DNA-capsid interactions, forms nematic phases under all conditions tried. The formation of liquid crystals has been developed as a method to detect subtle overall shape effects arising from DNA-subunit-derived polymorphism, an unusual role for the mesogenic state and a new tool for the study of filamentous phage structure.

  11. CHARACTERIZATION OF INTERACTION KINETICS BETWEEN CHIRAL SOLUTES AND HUMAN SERUM ALBUMIN BY USING HIGH-PERFORMANCE AFFINITY CHROMATOGRAPHY AND PEAK PROFILING

    PubMed Central

    Tong, Zenghan; Hage, David S.

    2011-01-01

    Peak profiling and high-performance columns containing immobilized human serum albumin (HSA) were used to study the interaction kinetics of chiral solutes with this protein. This approach was tested using the phenytoin metabolites 5-(3-hydroxyphenyl)-5-phenylhydantoin (m-HPPH) and 5-(4-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) as model analytes. HSA columns provided some resolution of the enantiomers for each phenytoin metabolite, which made it possible to simultaneously conduct kinetic studies on each chiral form. The dissociation rate constants for these interactions were determined by using both the single flow rate and multiple flow rate peak profiling methods. Corrections for non-specific interactions with the support were also considered. The final estimates obtained at pH 7.4 and 37°C for the dissociation rate constants of these interactions were 8.2–9.6 s−1 for the two enantiomers of m-HPPH and 3.2–4.1 s−1 for the enantiomers of p-HPPH. These rate constants agreed with previous values that have been reported for other drugs and solutes that have similar affinities and binding regions on HSA. The approach used in this report was not limited to phenytoin metabolites or HSA but could be applied to a variety of other chiral solutes and proteins. This method could also be adopted for use in the rapid screening of drug-protein interactions. PMID:21872871

  12. Site and chirality selective chemical modifications of boron nitride nanotubes (BNNTs) via Lewis acid-base interactions.

    PubMed

    Sundaram, Rajashabala; Scheiner, Steve; Roy, Ajit K; Kar, Tapas

    2015-02-01

    The pristine BNNTs contain both Lewis acid (boron) and Lewis base (nitrogen) centers at their surface. Interactions of ammonia and borane molecules, representatives of Lewis base and acid as adsorbates respectively, with matching sites at the surface of BNNTs, have been explored in the present DFT study. Adsorption energies suggest stronger chemisorption (about 15-20 kcal mol(-1)) of borane than ammonia (about 5-10 kcal mol(-1)) in both armchair (4,4) and zigzag (8,0) variants of the tube. NH3 favors (8,0) over the (4,4) tube, whereas BH3 exhibits the opposite preference, indicating some chirality dependence on acid-base interactions. A new feature of bonding is found in BH3/AlH3-BNNTs (at the edge site) complexes, where one hydrogen of the guest molecule is involved in three-center two-electron bonding, in addition to dative covalent bond (N: → B). This interaction causes a reversal of electron flow from borane/alane to BNNT, making the tube an electron acceptor, suggesting tailoring of electronic properties could be possible by varying strength of incoming Lewis acids. On the contrary, BNNTs always behave as electron acceptor in ammonia complexes. IR, XPS and NMR spectra show some characteristic features of complexes and can help experimentalists to identify not only structures of such complexes but also the location of the guest molecules and design second functionalizations. Interaction with several other neutral BF3, BCl3, BH2CH3 and ionic CH3(+) acids as well as amino group (CH3NH2 and NH2COOH) were also studied. The strongest interaction (>100 kcal mol(-1)) is found in BNNT-CH3(+) complexes and H-bonds are the only source of stability of NH2COOH-BNNT complexes. PMID:25559141

  13. Orion Exploration Flight Test-1 (EFT-1) Absolute Navigation Performance

    NASA Technical Reports Server (NTRS)

    Zanetti, Renato

    2015-01-01

    The Orion vehicle, being design to take men back to the Moon and beyond, successfully completed its first flight test, EFT-1 (Exploration Flight Test-1), on December 5th, 2014. The main objective of the test was to demonstrate the capability of re-enter into the Earth's atmosphere and safely splash-down into the pacific ocean. This un-crewed mission completes two orbits around Earth, the second of which is highly elliptical with an apogee of approximately 5908 km, higher than any vehicle designed for humans has been since the Apollo program. The trajectory was designed in order to test a high-energy re-entry similar to those crews will undergo during lunar missions. The mission overview is shown in Figure 1. The objective of this paper is to document the performance of the absolute navigation system during EFT-1 and to present its design.

  14. Consistency of the {pi}{delta} interaction in chiral perturbation theory

    SciTech Connect

    Wies, N.; Scherer, S.; Gegelia, J.

    2006-05-01

    We analyze the constraint structure of a spin-3/2 particle interacting with a pseudoscalar. Requiring the self consistency of the considered effective field theory imposes restrictions on the possible interaction terms. In the present case we derive two constraints among the three lowest-order {pi}{delta} interaction terms. From these constraints we find that the total Lagrangian is invariant under the so-called point transformation. On the other hand, demanding the invariance under the point transformation alone is less stringent and produces only classes of relations among the coupling constants.

  15. Light-front representation of chiral dynamics with Δ isobar and large- N c relations

    NASA Astrophysics Data System (ADS)

    Granados, C.; Weiss, C.

    2016-06-01

    Transverse densities describe the spatial distribution of electromagnetic current in the nucleon at fixed light-front time. At peripheral distances b = O( M π - 1 ) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). Recent work has shown that the EFT results can be represented in first-quantized form, as overlap integrals of chiral light-front wave functions describing the transition of the nucleon to soft-pion-nucleon intermediate states, resulting in a quantum-mechanical picture of the peripheral transverse densities. We now extend this representation to include intermediate states with Δ isobars and implement relations based on the large- N c limit of QCD. We derive the wave function overlap formulas for the Δ contributions to the peripheral transverse densities by way of a three-dimensional reduction of relativistic chiral EFT expressions. Our procedure effectively maintains rotational invariance and avoids the ambiguities with higher-spin particles in the light-front time-ordered approach. We study the interplay of π N and πΔ intermediate states in the quantum-mechanical picture of the densities in a transversely polarized nucleon. We show that the correct N c -scaling of the charge and magnetization densities emerges as the result of the particular combination of currents generated by intermediate states with degenerate N and Δ. The off-shell behavior of the chiral EFT is summarized in contact terms and can be studied easily. The methods developed here can be applied to other peripheral densities and to moments of the nucleon's generalized parton distributions.

  16. Light-front representation of chiral dynamics with Δ isobar and large-Nc relations

    DOE PAGES

    Granados, C.; Weiss, C.

    2016-06-13

    Transverse densities describe the spatial distribution of electromagnetic current in the nucleon at fixed light-front time. At peripheral distances b = O(Mπ–1) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). Recent work has shown that the EFT results can be represented in first-quantized form, as overlap integrals of chiral light-front wave functions describing the transition of the nucleon to soft-pion-nucleon intermediate states, resulting in a quantum-mechanical picture of the peripheral transverse densities. We now extend this representation to include intermediate states with Δ isobars and implement relations based on themore » large-Nc limit of QCD. We derive the wave function overlap formulas for the Δ contributions to the peripheral transverse densities by way of a three-dimensional reduction of relativistic chiral EFT expressions. Our procedure effectively maintains rotational invariance and avoids the ambiguities with higher-spin particles in the light-front time-ordered approach. We study the interplay of πN and πΔ intermediate states in the quantum-mechanical picture of the densities in a transversely polarized nucleon. We show that the correct Nc-scaling of the charge and magnetization densities emerges as the result of the particular combination of currents generated by intermediate states with degenerate N and Δ. The off-shell behavior of the chiral EFT is summarized in contact terms and can be studied easily. As a result, the methods developed here can be applied to other peripheral densities and to moments of the nucleon's generalized parton distributions.« less

  17. Chirality of weakly bound complexes: The potential energy surfaces for the hydrogen-peroxide−noble-gas interactions

    SciTech Connect

    Roncaratti, L. F. Leal, L. A.; Silva, G. M. de; Pirani, F.; Aquilanti, V.; Gargano, R.

    2014-10-07

    We consider the analytical representation of the potential energy surfaces of relevance for the intermolecular dynamics of weakly bound complexes of chiral molecules. In this paper we study the H{sub 2}O{sub 2}−Ng (Ng=He, Ne, Ar, Kr, and Xe) systems providing the radial and the angular dependence of the potential energy surface on the relative position of the Ng atom. We accomplish this by introducing an analytical representation which is able to fit the ab initio energies of these complexes in a wide range of geometries. Our analysis sheds light on the role that the enantiomeric forms and the symmetry of the H{sub 2}O{sub 2} molecule play on the resulting barriers and equilibrium geometries. The proposed theoretical framework is useful to study the dynamics of the H{sub 2}O{sub 2} molecule, or other systems involving O–O and S–S bonds, interacting by non-covalent forces with atoms or molecules and to understand how the relative orientation of the O–H bonds changes along collisional events that may lead to a hydrogen bond formation or even to selectivity in chemical reactions.

  18. Stability of the k = 3 Read-Rezayi state in chiral two-dimensional systems with tunable interactions

    NASA Astrophysics Data System (ADS)

    Abanin, D. A.; Papić, Z.; Barlas, Y.; Bhatt, R. N.

    2012-02-01

    The k = 3 Read-Rezayi (RR) parafermion quantum Hall state hosts non-Abelian excitations which provide a platform for universal topological quantum computation. Although the RR state may be realized at the filling factor ν = 12/5 in GaAs-based two-dimensional electron systems, the corresponding quantum Hall state is weak and at present nearly impossible to study experimentally. Here we argue that the RR state can alternatively be realized in a class of chiral materials with massless and massive Dirac-like band structure. This family of materials encompasses monolayer and bilayer graphene, as well as topological insulators. We show that, compared to GaAs, these systems provide several important advantages in realizing and studying the RR state. Most importantly, the effective interactions can be tuned in situ by varying the external magnetic field, and by designing the dielectric environment of the sample. This tunability enables the realization of RR state with controllable energy gaps in different Landau levels. It also allows one to probe the quantum phase transitions to other compressible and incompressible phases.

  19. Chiral squaring

    NASA Astrophysics Data System (ADS)

    Nagy, S.

    2016-07-01

    We construct the states and symmetries of N = 4 super-Yang-Mills by tensoring two N = 1 chiral multiplets and introducing two extra SUSY generators. This allows us to write the maximal N = 8 supergravity as four copies of the chiral multiplet. We extend this to higher dimensions and discuss applications to scattering amplitudes.

  20. Self-assembled cyclodextrin-modified gold nanoparticles on silica beads as stationary phase for chiral liquid chromatography and hydrophilic interaction chromatography.

    PubMed

    Li, Yuanyuan; Wei, Manman; Chen, Tong; Zhu, Nan; Ma, Yulong

    2016-11-01

    A facile strategy based on self-assembly of Au nanoparticles (AuNPs) (60±10nm in size) on the surfaces of amino-functionalized porous silica spheres under mild conditions was proposed. The resulting material possessed a core-shell structure in which AuNPs were the shell and silica spheres were the core. Then, thiolated-β-cyclodextrin (SH-β-CD) was covalently attached onto the AuNPs as chiral selector for the enantioseparation. The resultant packing material was evaluated by high-performance liquid chromatography (HPLC). The separations of nine pairs of enantiomers were achieved by using the new chiral stationary phase (CSP) in the reversed-phase liquid chromatography (RPLC) mode, respectively. The results showed the new CSP have more sufficient interaction with the analytes due to the existence of AuNPs on silica surfaces, resulting in faster mass transfer rate, compared with β-CD modified silica column. The result shed light on potential usage of chemical modified NPs as chiral selector for enantioseparation based on HPLC. In addition, the new phase was also used in hydrophilic interaction liquid chromatography (HILIC) to separate polar compounds and highly hydrophilic compounds. PMID:27591589

  1. 45 CFR 162.1601 - Health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Health care electronic funds transfers (EFT) and... SERVICES ADMINISTRATIVE DATA STANDARDS AND RELATED REQUIREMENTS ADMINISTRATIVE REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1601 Health care electronic funds transfers...

  2. 45 CFR 162.1601 - Health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Health care electronic funds transfers (EFT) and... SERVICES ADMINISTRATIVE DATA STANDARDS AND RELATED REQUIREMENTS ADMINISTRATIVE REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1601 Health care electronic funds transfers...

  3. 45 CFR 162.1601 - Health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Health care electronic funds transfers (EFT) and... Services ADMINISTRATIVE DATA STANDARDS AND RELATED REQUIREMENTS ADMINISTRATIVE REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1601 Health care electronic funds transfers...

  4. Light-front representation of chiral dynamics in peripheral transverse densities

    SciTech Connect

    Granados, Carlos G.; Weiss, Christian

    2015-07-31

    The nucleon's electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances b = O(M_pi^{-1}) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independent and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantized, quantum-mechanical view of chiral dynamics that is fully relativistic and exactly equivalent to the second-quantized, field-theoretical formulation. It relates the charge and magnetization densities measured in low-energy elastic scattering to the generalized parton distributions probed in peripheral high-energy scattering processes. The method can be applied to nucleon form factors of other operators, e.g. the energy-momentum tensor.

  5. Light-front representation of chiral dynamics in peripheral transverse densities

    DOE PAGES

    Granados, Carlos G.; Weiss, Christian

    2015-07-31

    The nucleon's electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances b = O(M_pi^{-1}) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independentmore » and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantized, quantum-mechanical view of chiral dynamics that is fully relativistic and exactly equivalent to the second-quantized, field-theoretical formulation. It relates the charge and magnetization densities measured in low-energy elastic scattering to the generalized parton distributions probed in peripheral high-energy scattering processes. The method can be applied to nucleon form factors of other operators, e.g. the energy-momentum tensor.« less

  6. Chiral magnetization textures stabilized by the Dzyaloshinskii-Moriya interaction during spin-orbit torque switching

    SciTech Connect

    Perez, N. Martinez, E.; Torres, L.

    2014-03-03

    We study the effect of the Dzyaloshinskii-Moriya interaction (DMI) on current-induced magnetic switching of a perpendicularly magnetized heavy-metal/ferromagnet/oxide trilayer both experimentally and through micromagnetic simulations. We report the generation of stable helical magnetization stripes for a sufficiently large DMI strength in the switching region, giving rise to intermediate states in the magnetization and confirming the essential role of the DMI on switching processes. We compare the simulation and experimental results to a macrospin model, showing the need for a micromagnetic approach. The influence of the temperature on the switching is also discussed.

  7. Breit interaction contribution to parity violating potentials in chiral molecules containing light nuclei.

    PubMed

    Berger, Robert

    2008-10-21

    The importance of the Breit interaction for an accurate prediction of parity violating energy differences between enantiomers is studied within electroweak quantum chemical frameworks. Besides two-electron orbit-orbit and spin-spin coupling contributions, the Breit interaction gives rise to the spin-other-orbit coupling term of the Breit-Pauli Hamiltonian. The present numerical study demonstrates that neglect of this latter term leads in hydrogen peroxide (H(2)O(2)) to relative deviations in the parity violating potential (V(pv)) by about 10%, whereas further relativistic corrections accounted for within a four-component Dirac-Hartree-Fock-Coulomb (DHFC) framework remain smaller, below 5%. Thus, the main source of discrepancy between previous one-component based (coupled perturbed) Hartree-Fock (HF) and four-component Dirac-Hartree-Fock results for parity violating potentials in H(2)O(2) is the neglect of the Breit contribution in DHFC. In heavier homologs of hydrogen peroxide the relative contribution of the spin-other-orbit coupling term to V(pv) decreases with increasing nuclear charge, whereas other relativistic effects become increasingly important. As shown for the H(2)X(2) (X = O,S,Se,Te,Po) series of molecules and for CHBrClF, to a good approximation these other relativistic influences on V(pv) can be accounted for in one-component based HF calculations with the help of relativistic enhancement factors proposed earlier in the theory of atomic parity violation.

  8. Exact thermodynamics and phase diagram of integrable t-J model with chiral interaction

    NASA Astrophysics Data System (ADS)

    Tavares, T. S.; Ribeiro, G. A. P.

    2016-09-01

    We study the phase diagram and finite temperature properties of an integrable generalization of the one-dimensional super-symmetric t-J model containing interactions explicitly breaking parity-time reversal (PT) symmetries. To this purpose, we apply the quantum transfer matrix method which results in a finite set of non-linear integral equations. We obtain numerical solutions to these equations leading to results for thermodynamic quantities as a function of temperature, magnetic field, particle density and staggering parameter. Studying the maxima lines of entropy at low but non zero temperature reveals the phase diagram of the model. There are ten different phases which we may classify in terms of the qualitative behaviour of auxiliary functions, closely related to the dressed energy functions.

  9. Nuclear Chirality

    SciTech Connect

    Starosta, Krzysztof

    2005-04-05

    Nuclear chirality is a novel manifestation of spontaneous symmetry breaking resulting from an orthogonal coupling of angular momentum vectors in triaxial nuclei. Three perpendicular angular momenta can form two systems of opposite handedness; the time reversal operator, which reverses orientation of each of the angular momentum components, relates these two systems. The status of current experimental searches for chiral doubling of states, as well as recent progress on the theoretical side is reviewed.

  10. Isotopic chirality

    SciTech Connect

    Floss, H.G.

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  11. Power counting regime of chiral effective field theory and beyond.

    SciTech Connect

    Hall, J. M.M.; Leinweber, D. B.; Young, R. D.; Physics; Univ. of Adelaide

    2010-08-10

    Chiral effective field theory ({chi}EFT) complements numerical simulations of quantum chromodynamics (QCD) on a space-time lattice. It provides a model-independent formalism for connecting lattice simulation results at finite volume and a variety of quark masses to the physical world. The asymptotic nature of the chiral expansion places the focus on the first few terms of the expansion. Thus, knowledge of the power-counting regime (PCR) of {chi}EFT, where higher-order terms of the expansion may be regarded as negligible, is as important as knowledge of the expansion itself. Through the consideration of a variety of renormalization schemes and associated parameters, techniques to identify the PCR where results are independent of the renormalization scheme are established. The nucleon mass is considered as a benchmark for illustrating this general approach. Because the PCR is small, the numerical simulation results are also examined to search for the possible presence of an intrinsic scale which may be used in a nonperturbative manner to describe lattice simulation results outside of the PCR. Positive results that improve on the current optimistic application of chiral perturbation theory ({chi}PT) beyond the PCR are reported.

  12. Power counting regime of chiral effective field theory and beyond

    SciTech Connect

    Hall, J. M. M.; Leinweber, D. B.; Young, R. D.

    2010-08-01

    Chiral effective field theory ({chi}EFT) complements numerical simulations of quantum chromodynamics (QCD) on a space-time lattice. It provides a model-independent formalism for connecting lattice simulation results at finite volume and a variety of quark masses to the physical world. The asymptotic nature of the chiral expansion places the focus on the first few terms of the expansion. Thus, knowledge of the power-counting regime (PCR) of {chi}EFT, where higher-order terms of the expansion may be regarded as negligible, is as important as knowledge of the expansion itself. Through the consideration of a variety of renormalization schemes and associated parameters, techniques to identify the PCR where results are independent of the renormalization scheme are established. The nucleon mass is considered as a benchmark for illustrating this general approach. Because the PCR is small, the numerical simulation results are also examined to search for the possible presence of an intrinsic scale which may be used in a nonperturbative manner to describe lattice simulation results outside of the PCR. Positive results that improve on the current optimistic application of chiral perturbation theory ({chi}PT) beyond the PCR are reported.

  13. Orion EFT-1 Cavity Heating Tile Experiments and Environment Reconstruction

    NASA Technical Reports Server (NTRS)

    Salazar, Giovanni; Amar, Adam; Oliver, Brandon; Hyatt, Andrew; Rezin, Marc

    2016-01-01

    Developing aerothermodynamic environments for deep cavities, such as those produced by micrometeoroids and orbital debris impacts, poses a great challenge for engineers. In order to assess existing cavity heating models, two one-inch diameter cavities were flown on the Orion Multi-Purpose Crew Vehicle during Exploration Flight Test 1 (EFT1). These cavities were manufactured with depths of 1.0 in and 1.4 in, and they were both instrumented. Instrumentation included surface thermocouples upstream, downstream and within the cavities, and additional thermocouples at the TPS-structure interface. This paper will present the data obtained, and comparisons with computational predictions will be shown. Additionally, the development of a 3D material thermal model will be described, which will be used to account for the three-dimensionality of the problem when interpreting the data. Furthermore, using a multi-dimensional inverse heat conduction approach, a reconstruction of a time- and space-dependent flight heating distribution during EFT1 will be presented. Additional discussions will focus on instrumentation challenges and calibration techniques specific to these experiments. The analysis shown will highlight the accuracies and/or deficiencies of current computational techniques to model cavity flows during hypersonic re-entry.

  14. Orion EFT-1 Catalytic Tile Experiment Overview and Flight Measurements

    NASA Technical Reports Server (NTRS)

    Salazar, Giovanni; Amar, Adam; Hyatt, Andrew; Rezin, Marc D.

    2016-01-01

    This paper describes the design and results of a surface catalysis flight experiment flown on the Orion Multipurpose Crew Vehicle during Exploration Flight Test 1 (EFT1). Similar to previous Space Shuttle catalytic tile experiments, the present test consisted of a highly catalytic coating applied to an instrumented TPS tile. However, the present catalytic tile experiment contained significantly more instrumentation in order to better resolve the heating overshoot caused by the change in surface catalytic efficiency at the interface between two distinct materials. In addition to collecting data with unprecedented spatial resolution of the "overshoot" phenomenon, the experiment was also designed to prove if such a catalytic overshoot would be seen in turbulent flow in high enthalpy regimes. A detailed discussion of the results obtained during EFT1 is presented, as well as the challenges associated with data interpretation of this experiment. Results of material testing carried out in support of this flight experiment are also shown. Finally, an inverse heat conduction technique is employed to reconstruct the flight environments at locations upstream and along the catalytic coating. The data and analysis presented in this work will greatly contribute to our understanding of the catalytic "overshoot" phenomenon, and have a significant impact on the design of future spacecraft.

  15. Compton scattering and nucleon polarisabilities in chiral EFT: Status and future

    NASA Astrophysics Data System (ADS)

    Grießhammer, Harald W.; McGovern, Judith A.; Phillips, Daniel R.

    2016-05-01

    We review theoretical progress and prospects for determining the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography.

  16. Enantiomeric pair of copper(II) polypyridyl-alanine complexes: Effect of chirality on their interaction with biomolecules.

    PubMed

    Ng, Chew Hee; Chan, Cheang Wei; Lai, Jing Wei; Ooi, Ing Hong; Chong, Kok Vei; Maah, Mohd Jamil; Seng, Hoi Ling

    2016-07-01

    Like chiral organic drugs, the chemical and biological properties of metal complexes can be dependent on chirality. Two pairs of [Cu(phen)(ala)(H2O)]X·xH2O (phen=1.10-phenanthroline: X=NO3(-); ala: l-alanine (l-ala), 1 and d-alanine (d-ala) 2; and (X=Cl(-); ala: l-ala, 3 and d-ala, 4) complex salts (x=number of lattice water molecules) have been synthesized and characterized. The crystal structure of 3 has been determined. The same pair of enantiomeric species, viz. [Cu(phen)(l-ala)(H2O)](+) and [Cu(phen)(d-ala)(H2O)](+), have been identified to be present in the aqueous solutions of both 1 and 3, and in those of both 2 and 4 respectively. Both 3 and 4 bind more strongly to ds(AT)6 than ds(CG)6. There is no or insignificant effect of the chirality of 3 and 4 on the production of hydroxyl radicals, binding to deoxyribonucleic acid from calf thymus (CT-DNA), ds(CG)6, G-quadruplex and 17-base pair duplex, and inhibition of both topoisomerase I and proteasome. Among the three proteasome proteolytic sites, the trypsin-like site is inhibited most strongly by these complexes. However, the chirality of 3 and 4 does affect the number of restriction enzymes inhibited, and their binding constants towards ds(AT)6 and serum albumin. PMID:27105312

  17. Enantiomeric pair of copper(II) polypyridyl-alanine complexes: Effect of chirality on their interaction with biomolecules.

    PubMed

    Ng, Chew Hee; Chan, Cheang Wei; Lai, Jing Wei; Ooi, Ing Hong; Chong, Kok Vei; Maah, Mohd Jamil; Seng, Hoi Ling

    2016-07-01

    Like chiral organic drugs, the chemical and biological properties of metal complexes can be dependent on chirality. Two pairs of [Cu(phen)(ala)(H2O)]X·xH2O (phen=1.10-phenanthroline: X=NO3(-); ala: l-alanine (l-ala), 1 and d-alanine (d-ala) 2; and (X=Cl(-); ala: l-ala, 3 and d-ala, 4) complex salts (x=number of lattice water molecules) have been synthesized and characterized. The crystal structure of 3 has been determined. The same pair of enantiomeric species, viz. [Cu(phen)(l-ala)(H2O)](+) and [Cu(phen)(d-ala)(H2O)](+), have been identified to be present in the aqueous solutions of both 1 and 3, and in those of both 2 and 4 respectively. Both 3 and 4 bind more strongly to ds(AT)6 than ds(CG)6. There is no or insignificant effect of the chirality of 3 and 4 on the production of hydroxyl radicals, binding to deoxyribonucleic acid from calf thymus (CT-DNA), ds(CG)6, G-quadruplex and 17-base pair duplex, and inhibition of both topoisomerase I and proteasome. Among the three proteasome proteolytic sites, the trypsin-like site is inhibited most strongly by these complexes. However, the chirality of 3 and 4 does affect the number of restriction enzymes inhibited, and their binding constants towards ds(AT)6 and serum albumin.

  18. Chiral Potts spin glass in d =2 and 3 dimensions

    NASA Astrophysics Data System (ADS)

    Ćaǧlar, Tolga; Berker, A. Nihat

    2016-09-01

    The chiral spin-glass Potts system with q =3 states is studied in d =2 and 3 spatial dimensions by renormalization-group theory and the global phase diagrams are calculated in temperature, chirality concentration p , and chirality-breaking concentration c , with determination of phase chaos and phase-boundary chaos. In d =3 , the system has ferromagnetic, left-chiral, right-chiral, chiral spin-glass, and disordered phases. The phase boundaries to the ferromagnetic, left- and right-chiral phases show, differently, an unusual, fibrous patchwork (microreentrances) of all four (ferromagnetic, left-chiral, right-chiral, chiral spin-glass) ordered phases, especially in the multicritical region. The chaotic behavior of the interactions, under scale change, are determined in the chiral spin-glass phase and on the boundary between the chiral spin-glass and disordered phases, showing Lyapunov exponents in magnitudes reversed from the usual ferromagnetic-antiferromagnetic spin-glass systems. At low temperatures, the boundaries of the left- and right-chiral phases become thresholded in p and c . In d =2 , the chiral spin-glass Potts system does not have a spin-glass phase, consistently with the lower-critical dimension of ferromagnetic-antiferromagnetic spin glasses. The left- and right-chirally ordered phases show reentrance in chirality concentration p .

  19. Prebiotic chirality

    NASA Astrophysics Data System (ADS)

    Mekki-Berrada, Ali

    Bringing closer phospholipids each other on a bilayer of liposome, causes their rotation around their fatty acids axis, generating a force which brings closer the two sheets of the bilayer. In this theoretical study I show that for getting the greater cohesion of the liposome, by these forces, the serine in the hydrophilic head must have a L chirality. In the case where the hydrophilic head is absent amino acids with L chirality could contribute to this cohesion by taking the place of L-serine. Some coenzymes having a configuration similar to ethanolamine may also contribute. This is the case of pyridoxamine, thiamine and tetrahydrofolic acid. The grouping of amino acids of L chirality and pyridoxamine on the wall could initialize the prebiotic metabolism of these L amino acids only. This would explain the origin of the homo-chirality of amino acids in living world. Furthermore I show that in the hydrophilic head, the esterification of glycerol-phosphate by two fatty acids go through the positioning of dihydroxyacetone-phosphate and L-glyceraldehyde-3-phosphate, but not of D-glyceraldehyde-3-phosphate, prior their hydrogenation to glycerol-3- phosphate. The accumulation of D-glyceraldehyde-3-phosphate in the cytoplasm displace the thermodynamic equilibria towards the synthesis of D-dATP from D-glyceraldehyde-3-phosphate, acetaldehyde and prebiotic adenine, a reaction which does not require a coenzyme in the biotic metabolism. D-dATP and thiamine, more prebiotic metabolism of L-amino acids on the wall, would initialize D-pentoses phosphate and D-nucleotides pathways from the reaction of D-glyceraldehyde-3-phosphate + dihydroxyacetone-phosphate + prebiotic nucleic bases. The exhaustion of the prebiotic glyceraldehyde (racemic) and the nascent biotic metabolism dominated by D-glyceraldehyde-3-phosphate, would explain the origin of homo-chirality of sugars in living world. References: http://en.wikiversity.org/wiki/Prebiotic_chirality

  20. ISO(4,1) symmetry in the EFT of inflation

    SciTech Connect

    Creminelli, Paolo; Emami, Razieh; Simonović, Marko; Trevisan, Gabriele E-mail: emami@mail.ipm.ir E-mail: gtrevi@sissa.it

    2013-07-01

    In DBI inflation the cubic action is a particular linear combination of the two, otherwise independent, cubic operators π-dot {sup 3} and π-dot (∂{sub i}π){sup 2}. We show that in the Effective Field Theory (EFT) of inflation this is a consequence of an approximate 5D Poincar and apos;e symmetry, ISO(4,1), non-linearly realized by the Goldstone π. This symmetry uniquely fixes, at lowest order in derivatives, all correlation functions in terms of the speed of sound c{sub s}. In the limit c{sub s} → 1, the ISO(4,1) symmetry reduces to the Galilean symmetry acting on π. On the other hand, we point out that the non-linear realization of SO(4,2), the isometry group of 5D AdS space, does not fix the cubic action in terms of c{sub s}.

  1. METHODS DEVELOPMENT FOR THE ANALYSIS OF CHIRAL PESTICIDES

    EPA Science Inventory

    Chiral compounds exist as a pair of nonsuperimposable mirror images called enantiomers. Enantiomers have identical physical-chemical properties, but their interactions with other chiral molecules, toxicity, biodegradation, and fate are often different. Many pharmaceutical com...

  2. Chiral heteropoly blues and controllable switching of achiral polyoxometalate clusters.

    PubMed

    Wang, Yizhan; Li, Haolong; Wu, Che; Yang, Yang; Shi, Lei; Wu, Lixin

    2013-04-22

    Managing the blues: Chiral heteropoly blues of achiral polyoxometalate clusters were created through an intermolecular interaction with a chiral organic compound. Controllable chiroptical switching of the cluster complexes was possible through reversible photochromism of the polyoxometalates (see picture).

  3. 1H and 13C NMR studies of glycine in anisotropic media: Double-quantum transitions and the effects of chiral interactions

    NASA Astrophysics Data System (ADS)

    Naumann, Christoph; Kuchel, Philip W.

    2011-07-01

    The 1H NMR spectrum of glycine in stretched gelatin gel and in cromolyn liquid crystal displays a well-resolved doublet due to 1H- 1H dipolar interaction. Multiple spectra were obtained within a wide range of offset frequencies of partially saturating radio-frequency (RF) radiation to generate steady-state irradiation envelopes or z-spectra of glycine. Maximal suppression of the doublet occurred when the irradiation was applied exactly at the centre frequency, between the two glycine peaks. This phenomenon is due to double-quantum transitions and is similar to our previous work on quadrupolar nuclei 2H (HDO) and 23Na +. When the 13C isotopomer glycine-2- 13C was used, the same effect was found in twice, split by 1JCH + 2 DCH. Additional signals in 1H and 13C NMR due to prochiral-chiral interactions were found when glycine-2- 13C was dissolved in chiral anisotropic gelatin and κ-carrageenan gels. The NMR spectra were successfully simulated assuming a 2JHH coupling constant of -16.5 Hz and two distinct dipolar coupling constants for the - 13CH 2- group ( DC,HA, and DC,HB).

  4. Chiral perturbation theory with nucleons

    SciTech Connect

    Meissner, U.G.

    1991-09-01

    I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, {pi}N scattering and the {sigma}-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.

  5. 77 FR 71035 - Financial Management Service; Proposed Collection of Information: Electronic Funds Transfer (EFT...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-28

    ... Fiscal Service Financial Management Service; Proposed Collection of Information: Electronic Funds Transfer (EFT) Market Research Study AGENCY: Financial Management Service, Fiscal Service, Treasury. ACTION...: Direct all written comments to Financial Management Service, Records and Information Management...

  6. Chirality Effect on Flory-Huggins Interaction Parameters in Polylactide-b-Poly(ethylene-co-1-butene)-b-Polylactide Triblock Copolymers

    NASA Astrophysics Data System (ADS)

    Cao, Weiqiang; Zhu, Lei; Rong, Lixia; Hsiao, Benjamin S.

    2009-03-01

    In this work, a set of well-defined polylactide-b-poly(ethylene-co-1-butene)-b-polylactide (PLA-PEB-PLA) triblock copolymers were synthesized by controlled ring-opening polymerization of corresponding lactide monomers (L-lactide and racemic mixture of D- and L-lactides) using Sn(Oct)2 as the catalyst. The volume fractions of PLA in the triblock copolymers were adjusted by tuning its molecular weight. The mesophase morphology and phase transitions in these triblock copolymers were studied by temperature-dependent small-angle X-ray scattering (SAXS). The Flory-Huggins interaction parameter χ between EB and lactide as a function of temperature were estimated from the order-disorder transition temperature (TODT) using the mean-field critical (χN)c values. The effects of PLA chirality on both Flory-Huggins interaction parameter and segmental lengths were investigated.

  7. Chiral recognition of zinc phthalocyanine on Cu(100) surface

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Chen, Xiu; Liu, Lacheng; Song, Xin; Liu, Shuyi; Liu, Juan; Ouyang, Hongping; Cai, Yingxiang; Liu, Xiaoqing; Pan, Haibing; Zhu, Junfa; Wang, Li

    2012-02-01

    The windmill-like chiral nature of individual ZnPc molecules adsorbed on Cu(100) surface at room temperature has been revealed by scanning tunneling microscopy (STM) and the origin of such chirality is attributed to asymmetrical charge transfer between the molecules and the copper surface. Such chiral enantiomers do recognize each other in molecular level and spontaneously form second-level chiral supramolecular structures with the same chirality during thermally driven movements. The interactions between the ZnPc molecules during such chiral recognition process have been discussed based on the analysis of the sub-molecule-resolution STM images.

  8. Electric dipole moments of light nuclei from {chi}EFT

    SciTech Connect

    Higa, Renato

    2013-03-25

    I present recent calculations of EDMs of light nuclei using chiral effective field theory techniques. At leading-order, we argue that they can be expressed in terms of six CP-violating low-energy constants. With our expressions, eventual non-zero measurements of EDMs of deuteron, helion, and triton can be combined to disentangle the different sources of CP-violation.

  9. Chiral selection on inorganic crystalline surfaces

    NASA Technical Reports Server (NTRS)

    Hazen, Robert M.; Sholl, David S.

    2003-01-01

    From synthetic drugs to biodegradable plastics to the origin of life, the chiral selection of molecules presents both daunting challenges and significant opportunities in materials science. Among the most promising, yet little explored, avenues for chiral molecular discrimination is adsorption on chiral crystalline surfaces - periodic environments that can select, concentrate and possibly even organize molecules into polymers and other macromolecular structures. Here we review experimental and theoretical approaches to chiral selection on inorganic crystalline surfaces - research that is poised to open this new frontier in understanding and exploiting surface-molecule interactions.

  10. Electromagnetic structure of A=2 and 3 nuclei in chiral effective field theory

    SciTech Connect

    M. Piarulli, L. Girlanda, L.E. Marcucci, S. Pastore, R. Schiavilla, M. Viviani

    2013-01-01

    The objectives of the present work are twofold. The first is to address and resolve some of the differences present in independent, chiral-effective-field-theory ({chi}EFT) derivations up to one loop, recently appeared in the literature, of the nuclear charge and current operators. The second objective is to provide a complete set of {chi}EFT predictions for the structure functions and tensor polarization of the deuteron, for the charge and magnetic form factors of {sup 3}He and {sup 3}H, and for the charge and magnetic radii of these few-nucleon systems. The calculations use wave functions derived from high-order chiral two- and three-nucleon potentials and Monte Carlo methods to evaluate the relevant matrix elements. Predictions based on conventional potentials in combination with {chi}EFT charge and current operators are also presented. There is excellent agreement between theory and experiment for all these observables for momentum transfers up to q {<=} 2.0--2.5 fm{sup -1}; for a subset of them, this agreement extends to momentum transfers as high as q ~ 5--6 fm{sup -1}. A complete analysis of the results is provided.

  11. Chiral analysis by capillary electrophoresis using antibiotics as chiral selector.

    PubMed

    Desiderio, C; Fanali, S

    1998-05-20

    The separation of chiral compounds by capillary electrophoresis (CE) is a very interesting field of research in different areas such as pharmaceutical, environmental, agricultural analysis etc. The separation of two enantiomers can be achieved in CE using a chiral environment interacting with the two analytes on forming diastereoisomers with different stability constants and thus different mobilities. A wide number of chiral selectors have been employed in CE and among them glycopeptide antibiotics exhibited excellent enantioselective properties towards a wide number of racemic compounds. Vancomycin, ristocetin A, rifamycins, teicoplanin, kanamycin, streptomycin, fradiomycin, and two vancomycin analogues, added to the background electrolyte (BGE), are the antibiotics studied by CE running the separation in untreated and/or coated fused-silica capillary. Due to adsorption and absorption phenomena, some drawbacks can be expected when using bare fused-silica capillary, e.g., changes of electroosmotic flow (EOF), broaden peaks, reduced efficiency and low sensitivity. Coated capillary and counter current mode can be the solution to overcome the above mentioned problems. This review surveys the separation of enantiomers by CE when macrocyclic antibiotics are used as chiral selector. The enantioselectivity can be easily controlled modifying several parameters such as antibiotic type and concentration, pH, ionic strength and concentration of the background electrolyte, organic modifier etc. The paper also presents a list of the latest chiral separations achieved by CE where antibiotics were used as chiral selector.

  12. Field induced spin chirality and chirality switching in magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Tartakovskaya, Elena V.

    2015-05-01

    The physical origin of the field-induced spin chirality experimentally observed in rare earth multilayers is determined. It is shown that the effect is possible due to the interplay between solid-state exchange interactions (the Ruderman-Kittel-Kasuya-Yosida and the Dsyaloshinsky-Moriya interactions), the external magnetic field and a special confinement of magnetic constituents. The presented model describes a certain temperature dependence of the chirality factor in agreement with experimental data and opens a new way to design nanostructured objects with predicted handedness.

  13. Chiral Magnetic Effect in Hydrodynamic Approximation

    NASA Astrophysics Data System (ADS)

    Zakharov, Valentin I.

    We review derivations of the chiral magnetic effect (ChME) in hydrodynamic approximation. The reader is assumed to be familiar with the basics of the effect. The main challenge now is to account for the strong interactions between the constituents of the fluid. The main result is that the ChME is not renormalized: in the hydrodynamic approximation it remains the same as for non-interacting chiral fermions moving in an external magnetic field. The key ingredients in the proof are general laws of thermodynamics and the Adler-Bardeen theorem for the chiral anomaly in external electromagnetic fields. The chiral magnetic effect in hydrodynamics represents a macroscopic manifestation of a quantum phenomenon (chiral anomaly). Moreover, one can argue that the current induced by the magnetic field is dissipation free and talk about a kind of "chiral superconductivity". More precise description is a quantum ballistic transport along magnetic field taking place in equilibrium and in absence of a driving force. The basic limitation is the exact chiral limit while temperature—excitingly enough—does not seemingly matter. What is still lacking, is a detailed quantum microscopic picture for the ChME in hydrodynamics. Probably, the chiral currents propagate through lower-dimensional defects, like vortices in superfluid. In case of superfluid, the prediction for the chiral magnetic effect remains unmodified although the emerging dynamical picture differs from the standard one.

  14. A construction of lattice chiral gauge theories

    NASA Astrophysics Data System (ADS)

    Narayanan, Rajamani; Neuberger, Herbert

    1995-02-01

    Path integration over Euclidean chiral fermions is replaced by the quantum mechanics of an auxiliary system of non-interacting fermions. Our construction avoids the no-go theorem and faithfully maintains all the known important features of chiral fermions, including the violation of some perturbative conservation laws by gauge field configurations of non-trivial topology.

  15. Chemical physics behind formation of effective and selective non-covalent interaction between fullerenes (C60 and C70) and a designed chiral monoporphyrin in solution

    NASA Astrophysics Data System (ADS)

    Ray, Anamika; Banerjee, Shrabanti; Bauri, Ajoy K.; Bhattacharya, Sumanta

    2016-02-01

    The present letter extricates the chemical physics behind non-covalent interaction between fullerenes (C60 and C70) and a designed chiral monoporphyrin molecule (1) in toluene. Steady state fluorescence studies on complex formation reveal higher binding constant (K) for C70/1 complex, i.e., K = 16,020 dm3 mol-1, and very good selectivity of binding, viz., KC70/1/KC60/1 ∼ 10.0. Time-resolved fluorescence study elicits role of static quenching mechanism behind photoexcited decay of 1* in presence of fullerene. Density functional theoretical calculations in vacuo validates the strong complexation between C70 and 1 and establishes the side-on binding motif of C70 towards 1 during complexation.

  16. Chiral edge states and fractional charge separation in a system of interacting bosons on a kagome lattice.

    PubMed

    Zhang, Xue-Feng; Eggert, Sebastian

    2013-10-01

    We consider the extended hard-core Bose-Hubbard model on a kagome lattice with boundary conditions on two edges. We find that the sharp edges lift the degeneracy and freeze the system into a striped order at 1/3 and 2/3 filling for zero hopping. At small hopping strengths, holes spontaneously appear and separate into fractional charges which move to the edges of the system. This leads to a novel edge liquid phase, which is characterized by fractional charges near the edges and a finite edge compressibility but no superfluid density. The compressibility is due to excitations on the edge which display a chiral symmetry breaking that is reminiscent of the quantum Hall effect and topological insulators. Large scale Monte Carlo simulations confirm the analytical considerations.

  17. Chiral Edge States and Fractional Charge Separation in a System of Interacting Bosons on a Kagome Lattice

    NASA Astrophysics Data System (ADS)

    Zhang, Xue-Feng; Eggert, Sebastian

    2013-10-01

    We consider the extended hard-core Bose-Hubbard model on a kagome lattice with boundary conditions on two edges. We find that the sharp edges lift the degeneracy and freeze the system into a striped order at 1/3 and 2/3 filling for zero hopping. At small hopping strengths, holes spontaneously appear and separate into fractional charges which move to the edges of the system. This leads to a novel edge liquid phase, which is characterized by fractional charges near the edges and a finite edge compressibility but no superfluid density. The compressibility is due to excitations on the edge which display a chiral symmetry breaking that is reminiscent of the quantum Hall effect and topological insulators. Large scale Monte Carlo simulations confirm the analytical considerations.

  18. Percolation features of cooperative Jahn-Teller systems: Ising EFT framework

    NASA Astrophysics Data System (ADS)

    Moujaes, Elie A.; Abou Ghantous, Michel

    2014-08-01

    Elastic exchange between two nearest Jahn-Teller (JT) centers in two or three dimensional dense crystals, can give an ordered macroscopic distortion known as cooperative JT effect (CJTE). A very diluted JT crystal does not show this effect. In the dynamic JT effect (DJTE), tunneling between different equivalent distorted wells has a pronounced influence on the CJTE. We investigate this phenomenon using a progressive increase in the concentration of these centers in the JT crystals, based on a bond percolation vector spin analogy technique within the framework of effective field theory (EFT). Mean field theory (MFT) was extensively used in previous studies of CJTE; however it neither includes correlation between JT centers in the lattice due to the complexity of the distortion field in the crystal nor the effect of tunneling between wells. We resort to an alternative procedure, by describing a JT center as a pseudo-spin vector , induced to represent the degenerate JT-distorted states, where two nearest JT centers interact via an elastic exchange described by an Ising type spin interaction. The DJTE is considered to be similar to an elastic transverse field term in the Hamiltonian portraying the effect of tunneling between equivalent wells in the adiabatic potential energy surface (APES). We will be particularly discussing S = 1, S = 3/2 and S = 5/2 spin cases, where 2 S + 1 wells in the APES are present and what JT systems they actually represent, with a percolative mechanism applied to the interactions between different JT centers. The different lattices are distinguished by their coordination numbers. Strong tunneling effects can suppress the CJTE and lead to a new state of criticality. Generalizations to higher spin systems will be obtained using a scaling technique. For the relevant distortions, we determine single site correlations, the macroscopic average distortion describing a structural phase transition and the elastic isothermal susceptibility as a

  19. Chiral Dynamics 2006

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammad W.; Gao, Haiyan; Weller, Henry R.; Holstein, Barry

    2007-10-01

    of singular potentials and power counting / M.P. Valderrrama. The challenge of calculating Baryon-Baryon scattering from lattice QCD / S.R. Beane. Precise absolute np scattering cross section and the charged [Pie symbol] NN coupling constant / S. E. Vigdor. Probing hadronic parity violation using few nucleon systems / S.A. Page. Extracting the neutron-neutron scattering length from neutron-deuteron breakup / C.R. Howell. Extraction of [equationl] from [Pie symbol]-d --> [equation] / A. Grudestig. The three- and four-body system with large scattering length / L. Platter. 3N and 4N systems and the Ay puzzle / T. Clegg. Recent progress in nuclear lattice simulations with effective field theory / D. Lee. Few-body studies at KVI / J.G. Messchendorp. Results of three nucleon experiments from RIKEN / K. Sekiguchi. A new opportunity to measure the total photoabsorption cross section of helium / P. T. Debevec. Three-body photodisintegration of 3He with double polarizations / X. Zong. Large two-pion exchange contributions to the pp --> pp[Pie symbol]0 reaction / F. Myhrer. Towards a systematic theory of nuclear forces / E. Epelbaum. Ab initio calculations of eletromagnetic reactions in light nuclei / W. Leidemann. Electron scattering from a polarized deuterium target at BLAST / R. Fatemi. Neutron-neutron scattering length from the reaction [equation] / V. Lensky. Renormalization group analysis of nuclear current operators / S.X. Nakamura. Recent results and future plans at MAX-LAB / K.G. Fissum. Nucleon polarizabilities from deutron compton scattering, and its lessons for chiral power counting / H. W. Grie hammer. Compton scattering on HE-3 / D. Choudhury -- pt. D. Hadron structure and Meson-Baryon interactions. Summary of the working group on Hadron structure and Meson-Baryon interactions / G. Feldman and T.R. Hemmert. Finite volume effects: lattice meets CHPT / G. Schierholz. Lattice discretization errors in chiral effective field theories / B.C. Tiburzi. SU(3)-breaking

  20. 45 CFR 162.1603 - Operating rules for health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Operating rules for health care electronic funds... REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1603 Operating rules for health care electronic funds transfers (EFT) and remittance advice transaction. On and after January...

  1. 45 CFR 162.1603 - Operating rules for health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Operating rules for health care electronic funds... REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1603 Operating rules for health care electronic funds transfers (EFT) and remittance advice transaction. On and after January...

  2. 45 CFR 162.1603 - Operating rules for health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Operating rules for health care electronic funds... REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1603 Operating rules for health care electronic funds transfers (EFT) and remittance advice transaction. On and after January...

  3. Generation of chiral spin state by quantum simulation

    NASA Astrophysics Data System (ADS)

    Tanamoto, Tetsufumi

    2016-06-01

    Chirality of materials in nature appears when there are asymmetries in their lattice structures or interactions in a certain environment. Recent development of quantum simulation technology has enabled the manipulation of qubits. Accordingly, chirality can be realized intentionally rather than passively observed. Here we theoretically provide simple methods to create a chiral spin state in a spin-1/2 qubit system on a square lattice. First, we show that switching on and off the Heisenberg and X Y interactions produces the chiral interaction directly in the effective Hamiltonian without controlling local fields. Moreover, when initial states of spin qubits are appropriately prepared, we prove that the chirality with desirable phase is dynamically obtained. Finally, even for the case where switching on and off the interactions is infeasible and the interactions are always on, we show that, by preparing an asymmetric initial qubit state, the chirality whose phase is π /2 is dynamically generated.

  4. Enhanced Chiral Recognition by Cyclodextrin Dimers

    PubMed Central

    Voskuhl, Jens; Schaepe, Kira; Ravoo, Bart Jan

    2011-01-01

    In this article we investigate the effect of multivalency in chiral recognition. To this end, we measured the host-guest interaction of a β-cyclodextrin dimer with divalent chiral guests. We report the synthesis of carbohydrate-based water soluble chiral guests functionalized with two borneol, menthol, or isopinocampheol units in either (+) or (−) configuration. We determined the interaction of these divalent guests with a β-cyclodextrin dimer using isothermal titration calorimetry. It was found that—in spite of a highly unfavorable conformation—the cyclodextrin dimer binds to guest dimers with an increased enantioselectivity, which clearly reflects the effect of multivalency. PMID:21845101

  5. Chiral mirrors

    NASA Astrophysics Data System (ADS)

    Plum, Eric; Zheludev, Nikolay I.

    2015-06-01

    Mirrors are used in telescopes, microscopes, photo cameras, lasers, satellite dishes, and everywhere else, where redirection of electromagnetic radiation is required making them arguably the most important optical component. While conventional isotropic mirrors will reflect linear polarizations without change, the handedness of circularly polarized waves is reversed upon reflection. Here, we demonstrate a type of mirror reflecting one circular polarization without changing its handedness, while absorbing the other. The polarization-preserving mirror consists of a planar metasurface with a subwavelength pattern that cannot be superimposed with its mirror image without being lifted out of its plane, and a conventional mirror spaced by a fraction of the wavelength from the metasurface. Such mirrors enable circularly polarized lasers and Fabry-Pérot cavities with enhanced tunability, gyroscopic applications, polarization-sensitive detectors of electromagnetic waves, and can be used to enhance spectroscopies of chiral media.

  6. Chiral shielding

    SciTech Connect

    Babukhadia, L.; Berdnikov, Ya. A.; Ivanov, A. N.; Scadron, M. D.

    2000-08-01

    We demonstrate how a chiral soft pion theorem (SPT) shields the scalar meson ground-state isoscalar {sigma}(600-700) and isospinor {kappa}(800-900) from detection in a{sub 1}{yields}{pi}({pi}{pi}){sub swave}, {gamma}{gamma}{yields}2{pi}{sup 0}, {pi}{sup -}p{yields}{pi}{sup -}{pi}{sup +}n and K{sup -}p{yields}K{sup -}{pi}{sup +}n processes. While pseudoscalar meson PVV transitions are known to be determined by (only) quark loop diagrams, the above SPT also constrains scalar meson SVV transitions to be governed (only) by meson loop diagrams. We apply this latter SVV theorem to a{sub 0}{yields}{gamma}{gamma} and f{sub 0}{yields}{gamma}{gamma} decays. (c) 2000 The American Physical Society.

  7. Chiral drag force

    NASA Astrophysics Data System (ADS)

    Rajagopal, Krishna; Sadofyev, Andrey V.

    2015-10-01

    We provide a holographic evaluation of novel contributions to the drag force acting on a heavy quark moving through strongly interacting plasma. The new contributions are chiral in the sense that they act in opposite directions in plasmas containing an excess of left- or right-handed quarks. The new contributions are proportional to the coefficient of the axial anomaly, and in this sense also are chiral. These new contributions to the drag force act either parallel to or antiparallel to an external magnetic field or to the vorticity of the fluid plasma. In all these respects, these contributions to the drag force felt by a heavy quark are analogous to the chiral magnetic effect (CME) on light quarks. However, the new contribution to the drag force is independent of the electric charge of the heavy quark and is the same for heavy quarks and antiquarks, meaning that these novel effects do not in fact contribute to the CME current. We show that although the chiral drag force can be non-vanishing for heavy quarks that are at rest in the local fluid rest frame, it does vanish for heavy quarks that are at rest in a suitably chosen frame. In this frame, the heavy quark at rest sees counterpropagating momentum and charge currents, both proportional to the axial anomaly coefficient, but feels no drag force. This provides strong concrete evidence for the absence of dissipation in chiral transport, something that has been predicted previously via consideration of symmetries. Along the way to our principal results, we provide a general calculation of the corrections to the drag force due to the presence of gradients in the flowing fluid in the presence of a nonzero chemical potential. We close with a consequence of our result that is at least in principle observable in heavy ion collisions, namely an anticorrelation between the direction of the CME current for light quarks in a given event and the direction of the kick given to the momentum of all the heavy quarks and

  8. Understanding complex chiral plasmonics.

    PubMed

    Duan, Xiaoyang; Yue, Song; Liu, Na

    2015-11-01

    Chiral nanoplasmonics exhibits great potential for novel nanooptical devices due to the generation of a strong chiroptical response within nanoscale metallic structures. Recently, a number of different approaches have been utilized to create chiral nanoplasmonic structures. However, particularly for tailoring nanooptical chiral sensing devices, the understanding of the resulting chiroptical response when coupling chiral and achiral structures together is crucial and has not been completely understood to date. Here, we present a thorough and step-by-step experimental study to understand the intriguing chiral-achiral coupling scheme. We set up a hybrid plasmonic system, which bears resemblance to the 'host-guest' system in supramolecular chemistry to analyze and explain the complex chiral response both at the chiral and achiral plasmonic resonances. We also provide an elegant and simple analytical model, which can describe, predict, and comprehend the chiroptical spectra in detail. Our study will shed light on designing well-controlled chiral-achiral coupling platforms for reliable chiral sensing.

  9. Chiral Thirring–Wess model

    SciTech Connect

    Rahaman, Anisur

    2015-10-15

    The vector type of interaction of the Thirring–Wess model was replaced by the chiral type and a new model was presented which was termed as chiral Thirring–Wess model in Rahaman (2015). The model was studied there with a Faddeevian class of regularization. Few ambiguity parameters were allowed there with the apprehension that unitarity might be threatened like the chiral generation of the Schwinger model. In the present work it has been shown that no counter term containing the regularization ambiguity is needed for this model to be physically sensible. So the chiral Thirring–Wess model is studied here without the presence of any ambiguity parameter and it has been found that the model not only remains exactly solvable but also does not lose the unitarity like the chiral generation of the Schwinger model. The phase space structure and the theoretical spectrum of this new model have been determined in the present scenario. The theoretical spectrum is found to contain a massive boson with ambiguity free mass and a massless boson.

  10. Chirality and gravitational parity violation.

    PubMed

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented. PMID:25919812

  11. Chirality and gravitational parity violation.

    PubMed

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented.

  12. Three-dimensional Chiral Plasmonic Oligomers

    NASA Astrophysics Data System (ADS)

    Hentschel, Mario

    2013-03-01

    We demonstrate chiral optical response in stacked arrangements of plasmonic nanostructures. We show that three-dimensional arrangements of plasmonic ``meta-atoms'' only exhibit a chiral optical response if similar plasmonic ``atoms'' are arranged in a handed fashion as we require resonant plasmonic coupling. Moreover, we demonstrate that such particle groupings, similarly to molecular systems, possess the capability to encode their three-dimensional arrangement in unique and well-modulated spectra, making them ideal candidates for a three-dimensional chiral plasmon ruler. Furthermore, we discuss the onset of a broadband chiral optical response in the wavelength regime between 700 nm and 3500 nm upon charge transfer between the nanoparticles. We show in experiment and simulation that this response is due to the ohmic contact between adjacent particles which causes a strong red-shift of the fundamental mode. The geometrical shape of the resulting fused particles allows for efficient excitation of higher order modes. Calculated spectra and field distributions confirm our interpretation and show a number of interacting plasmonic modes. Finally, we will discuss plasmonic diastereomers which consist of multiple chiral centers. We find that the chiral optical response of the composite molecules can be traced back to the properties of the constituting building blocks. We demonstrate that the optical response of complex chiral plasmonic systems can be decomposed and understood in terms of fundamental building blocks, offering simple and straightforward design rules for future applications such as chiral optical elements and enantiomer sensors.

  13. Instantons, chiral dynamics, and hadronic resonances

    SciTech Connect

    Cristoforetti, M.; Faccioli, P.; Traini, M.

    2007-03-01

    We use the interacting instanton liquid model (IILM) as a tool to study the role played by the chiral interactions in the lowest-lying vector and axial-vector meson resonances. We find that narrow a{sub 1} and {rho} meson resonances can be generated by instanton-induced chiral forces, even in the absence of confinement. In the IILM, these hadrons are found to have masses only about 30% larger than the experimental value and small width < or approx. 10-50 MeV. This result suggests that chiral interactions are very important in these systems and provide most of their mass. We explore the decaying patterns of the {rho} meson, in the absence of confinement. We argue that, in our model where only chiral forces are switched on, this meson decays dissociating into its quark-antiquark constituents.

  14. Nuclear chiral dynamics and thermodynamics

    NASA Astrophysics Data System (ADS)

    Holt, Jeremy W.; Kaiser, Norbert; Weise, Wolfram

    2013-11-01

    This presentation reviews an approach to nuclear many-body systems based on the spontaneously broken chiral symmetry of low-energy QCD. In the low-energy limit, for energies and momenta small compared to a characteristic symmetry breaking scale of order 1 GeV, QCD is realized as an effective field theory of Goldstone bosons (pions) coupled to heavy fermionic sources (nucleons). Nuclear forces at long and intermediate distance scales result from a systematic hierarchy of one- and two-pion exchange processes in combination with Pauli blocking effects in the nuclear medium. Short distance dynamics, not resolved at the wavelengths corresponding to typical nuclear Fermi momenta, are introduced as contact interactions between nucleons. Apart from a set of low-energy constants associated with these contact terms, the parameters of this theory are entirely determined by pion properties and low-energy pion-nucleon scattering observables. This framework (in-medium chiral perturbation theory) can provide a realistic description of both isospin-symmetric nuclear matter and neutron matter, with emphasis on the isospin-dependence determined by the underlying chiral NN interaction. The importance of three-body forces is emphasized, and the role of explicit Δ(1232)-isobar degrees of freedom is investigated in detail. Nuclear chiral thermodynamics is developed and a calculation of the nuclear phase diagram is performed. This includes a successful description of the first-order phase transition from a nuclear Fermi liquid to an interacting Fermi gas and the coexistence of these phases below a critical temperature Tc. Density functional methods for finite nuclei based on this approach are also discussed. Effective interactions, their density dependence and connections to Landau Fermi liquid theory are outlined. Finally, the density and temperature dependences of the chiral (quark) condensate are investigated.

  15. Electromagnetic processes in a chiEFT framework

    SciTech Connect

    L. Girlanda, S. Pastore, R. Schiavilla, M. Viviani

    2010-09-01

    Recently, we have derived a two--nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom. The calculation of the currents has been carried out to include N$^3$LO corrections, consisting of two--pion exchange and contact contributions. The latter involve unknown low-energy constants (LECs), some of which have been fixed by fitting the $np$ S- and P-wave phase shifts up to 100 MeV lab energies. The remaining LECs entering the current operator are determined so as to reproduce the experimental deuteron and trinucleon magnetic moments, as well as the $np$ cross section. This electromagnetic current operator is utilized to study the $nd$ and $n^3$He radiative captures at thermal neutron energies. Here we discuss our results stressing on the important role played by the LECs in reproducing the experimental data.

  16. Direct separation of the enantiomers of oxaliplatin on a cellulose-based chiral stationary phase in hydrophilic interaction liquid chromatography mode.

    PubMed

    Gallinella, Bruno; Bucciarelli, Lucia; Zanitti, Leo; Ferretti, Rosella; Cirilli, Roberto

    2014-04-25

    (R,R)-oxaliplatin is an anticancer enantiopure active pharmaceutical ingredient. Little attention has been devoted to the analysis of its enantiomeric composition. The enantioselective HPLC method reported in the current Pharmacopoeias shows clear disadvantages with regard to the low resolution and long elution times. In this work, it has been proven the applicability of a last generation polysaccharide-based chiral stationary phase (CSP), i.e. the Chiralpak IC-3, in the enantioseparation of oxaliplatin. Experimental results demonstrated the benefits arising from the development of enantioselective hydrophilic interaction liquid chromatography (HILIC) based strategies. A baseline separation with resolution factor of 5.8 was achieved using a 100mm×4.6mm I.D. IC-3 column set at the temperature of 40°C and a mobile phase consisting of acetonitrile-water 100:5 mixture. At a flow rate of 1mLmin(-1) the separation was completed within 8min. The optimized method was proven to be sensitive with LOD and LOQ of the enantiomeric impurity of 0.07 and 0.21μgmL(-1), respectively.

  17. Tritium β decay in chiral effective field theory

    DOE PAGES

    Baroni, A.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Schiavilla, R.; Viviani, M.

    2016-08-18

    We evaluate the Fermi and Gamow-Teller (GT) matrix elements in tritiummore » $$\\beta$$-decay by including in the charge-changing weak current the corrections up to one loop recently derived in nuclear chiral effective field theory ($$\\chi$$ EFT). The trinucleon wave functions are obtained from hyperspherical-harmonics solutions of the Schroedinger equation with two- and three-nucleon potentials corresponding to either $$\\chi$$ EFT (the N3LO/N2LO combination) or meson-exchange phenomenology (the AV18/UIX combination). We find that contributions due to loop corrections in the axial current are, in relative terms, as large as (and in some cases, dominate) those from one-pion exchange, which nominally occur at lower order in the power counting. Furthermore, we also provide values for the low-energy constants multiplying the contact axial current and three-nucleon potential, required to reproduce the experimental GT matrix element and trinucleon binding energies in the N3LO/N2LO and AV18/UIX calculations.« less

  18. Tritium β decay in chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Baroni, A.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Schiavilla, R.; Viviani, M.

    2016-08-01

    We evaluate the Fermi and Gamow-Teller (GT) matrix elements in tritium β decay by including in the charge-changing weak current the corrections up to one loop recently derived in nuclear chiral effective field theory (χ EFT ). The trinucleon wave functions are obtained from hyperspherical-harmonics solutions of the Schrödinger equation with two- and three-nucleon potentials corresponding to either χ EFT (the N3LO/N2LO combination) or meson-exchange phenomenology (the AV18/UIX combination). We find that contributions due to loop corrections in the axial current are, in relative terms, as large as (and in some cases, dominate) those from one-pion exchange, which nominally occur at lower order in the power counting. We also provide values for the low-energy constants multiplying the contact axial current and three-nucleon potential, required to reproduce the experimental GT matrix element and trinucleon binding energies in the N3LO/N2LO and AV18/UIX calculations.

  19. Introduction to chiral symmetry

    SciTech Connect

    Koch, V.

    1996-01-08

    These lectures are an attempt to a pedagogical introduction into the elementary concepts of chiral symmetry in nuclear physics. Effective chiral models such as the linear and nonlinear sigma model will be discussed as well as the essential ideas of chiral perturbation theory. Some applications to the physics of ultrarelativistic heavy ion collisions will be presented.

  20. Magnetic Chirality Induced from Ruderman-Kittel-Kasuya-Yosida Interaction at an Interface of a Ferromagnet/Heavy Metal Heterostructure

    NASA Astrophysics Data System (ADS)

    Shibuya, Taira; Matsuura, Hiroyasu; Ogata, Masao

    2016-11-01

    We study a microscopic derivation and the properties of the Dzyaloshinskii-Moriya interaction (DMI) between local magnetic moments in ferromagnet/heavy metal heterostructures. First, we derive DMI by Ruderman-Kittel-Kasuya-Yosida interaction through electrons in a heavy metal with Rashba spin orbit interaction (SOI). Next, we study the dependences of the DMI on the Rashba SOI, lattice constant, and chemical potential. We find that the DMI amplitude increases linearly when the Rashba SOI is small, has a maximum when the Rashba SOI is comparable to the hopping integral, and decreases when the Rashba SOI is large. The sign of the DMI not only changes depending on the sign of the Rashba SOI but also the lattice constants and the chemical potential of the heavy metal. The implications of the obtained results for experiments are discussed.

  1. Control of normal chirality at hexagonal interfaces

    SciTech Connect

    Haraldsen, Jason T; Fishman, Randy Scott

    2010-01-01

    We study the net chirality created by the Dzyaloshinkii-Moriya interaction (DMI) at the boundary between hexagonal layers of magnetic and non-magnetic materials. It is shown that another mechanism besides elastic torsion is required to understand the change in chirality observed in Dy/Y multilayers during field-cooling. The paper shows that due to the overlap between magnetic and non-magnetic atoms, interfacial steps may produce a DMI normal to the interface in magnetic heterostructures.

  2. Intelligent chiral sensing based on supramolecular and interfacial concepts.

    PubMed

    Ariga, Katsuhiko; Richards, Gary J; Ishihara, Shinsuke; Izawa, Hironori; Hill, Jonathan P

    2010-01-01

    Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized.

  3. Intelligent Chiral Sensing Based on Supramolecular and Interfacial Concepts

    PubMed Central

    Ariga, Katsuhiko; Richards, Gary J.; Ishihara, Shinsuke; Izawa, Hironori; Hill, Jonathan P.

    2010-01-01

    Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized. PMID:22163577

  4. CAPILLARY ELECTROPHORESIS FOR ENANTIOMER SEPARATION AND MEASUREMENT OF ENANTIOSELECTIVITY OF CHIRAL POLLUTANTS IN THE ENVIRONMENT

    EPA Science Inventory

    Chiral pollutants exist as 2 species, -- enantiomers - that have identical physical and chemical properties except when they interact with enzymes or other chiral molecules; then they usually react selectively. This enantioselectivity results in different rates of microbial trans...

  5. Chirally symmetric but confining dense, cold matter

    NASA Astrophysics Data System (ADS)

    Glozman, L. Ya.; Wagenbrunn, R. F.

    2008-03-01

    The folklore tradition about the QCD phase diagram is that at the chiral restoration phase transition at finite density hadrons are deconfined and there appears the quark matter. We address this question within the only known exactly solvable confining and chirally symmetric model. It is postulated within this model that there exists linear Coulomb-like confining interaction. The chiral symmetry breaking and the quark Green function are obtained from the Schwinger-Dyson (gap) equation while the color-singlet meson spectrum results from the Bethe-Salpeter equation. We solve this model at T=0 and finite chemical potential μ and obtain a clear chiral restoration phase transition at the critical value μcr. Below this value the spectrum is similar to the previously obtained one at μ=0. At μ>μcr the quarks are still confined and the physical spectrum consists of bound states which are arranged into a complete set of exact chiral multiplets. This explicitly demonstrates that a chirally symmetric matter consisting of confined but chirally symmetric hadrons at finite chemical potential is also possible in QCD. If so, there must be nontrivial implications for astrophysics.

  6. Chirally symmetric but confining dense, cold matter

    SciTech Connect

    Glozman, L. Ya.; Wagenbrunn, R. F.

    2008-03-01

    The folklore tradition about the QCD phase diagram is that at the chiral restoration phase transition at finite density hadrons are deconfined and there appears the quark matter. We address this question within the only known exactly solvable confining and chirally symmetric model. It is postulated within this model that there exists linear Coulomb-like confining interaction. The chiral symmetry breaking and the quark Green function are obtained from the Schwinger-Dyson (gap) equation while the color-singlet meson spectrum results from the Bethe-Salpeter equation. We solve this model at T=0 and finite chemical potential {mu} and obtain a clear chiral restoration phase transition at the critical value {mu}{sub cr}. Below this value the spectrum is similar to the previously obtained one at {mu}=0. At {mu}>{mu}{sub cr} the quarks are still confined and the physical spectrum consists of bound states which are arranged into a complete set of exact chiral multiplets. This explicitly demonstrates that a chirally symmetric matter consisting of confined but chirally symmetric hadrons at finite chemical potential is also possible in QCD. If so, there must be nontrivial implications for astrophysics.

  7. Optical properties and circular dichroism of chiral metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Fan, Zhiyuan; Govorov, Alexander; OU Team

    2013-03-01

    In nature, biological systems are built up by homochiral building blocks, such as a sugar and protein. Circular dichroism (CD) is an effective tool of resolving molecular conformations. It utilizes circularly polarized light to detect differential absorption of chiral materials. In medicine, it will help us to develop new drugs and therapies, if we understand the connection between the physical or chemical properties of drug molecules and their conformations. With the rapid development of nanotechnologies, chiral nanomaterials attract lots of attention nowadays. CD signals of chiral molecules can be enhanced or shifted to the visible band in the presence of plasmonic nanocrystals. Here we present a plasmonic CD mechanism from a single chiral metal nanocrystal. The mechanism is essentially different from the dipolar plasmon-plasmon interaction in a chiral NP assembly, which mimics the CD mechanism of chiral molecules. Chiral metal nanocrystals are expected to have promising applications in biosensing. Recently a few experimental papers reported successful realizations of chiral nanocrystals in a macroscopic ensemble in solution. Particularly the paper described silver nanoparticles grown on chiral template molecules and demonstrating characteristic CD signals at a plasmonic wavelength. The plasmonic CD signals in Ref. can come from a dipolar plasmon-molecule interaction or from a chiral shape of nanocrystals. This work was supported by the NSF (project: CBET- 0933782) and by the Volkswagen Foundation.

  8. Chirality in photonic systems

    NASA Astrophysics Data System (ADS)

    Solnyshkov, Dmitry; Malpuech, Guillaume

    2016-10-01

    The optical modes of photonic structures are the so-called TE and TM modes that bring intrinsic spin-orbit coupling and chirality to these systems. This, combined with the unique flexibility of design of the photonic potential, and the possibility to mix photon states with excitonic resonances, sensitive to magnetic field and interactions, allows us to achieve many phenomena, often analogous to other solid-state systems. In this contribution, we review in a qualitative and comprehensive way several of these realizations, namely the optical spin Hall effect, the creation of spin currents protected by a non-trivial geometry, the Berry curvature for photons, and the photonic/polaritonic topological insulator.

  9. μ → e γ in the 2HDM: an exercise in EFT

    NASA Astrophysics Data System (ADS)

    Davidson, Sacha

    2016-05-01

    The 2 Higgs Doublet Model of type III has renormalisable Lepton Flavour-Violating couplings, and its one- and two-loop ("Barr-Zee") contributions to μ → e γ are known. In the decoupling limit, where the mass scale M of the second doublet is much greater than the electroweak scale, the model can be parametrised with an Effective Field Theory (EFT) containing dimension-six operators. The 1/M^2 terms of the exact calculation are reproduced in the EFT, provided that the four-fermion operator basis below the weak scale is enlarged with respect to the SU(2)-invariant Buchmuller-Wyler list. It is found that the dominant two-loop "Barr-Zee" contributions arise mostly in two-loop matching and running, and that dimension-eight operators might be numerically relevant.

  10. Estimating Orion Heat Shield Failure Due To Ablator Cracking During The EFT-1 Mission

    NASA Technical Reports Server (NTRS)

    Vander Kam, Jeremy C.; Gage, Peter

    2016-01-01

    The Orion EFT-1 heatshield suffered from two major certification challenges: First, the mechanical properties used in design were not evident in the flight hardware and second, the flight article itself cracked during fabrication. The combination of these events motivated the Orion Program to pursue an engineering-level Probabilistic Risk Assessment (PRA) as part of heatshield certification rationale. The PRA provided loss of Mission (LOM) likelihoods considering the probability of a crack occurring during the mission and the likelihood of subsequent structure over-temperature. The methods and input data for the PRA are presented along with a discussion of the test data used to anchor the results. The Orion program accepted an EFT-1 Loss of Vehicle (LOV) risk of 1-in-160,000 due to in-mission Avcoat cracking based on the results of this analysis. Conservatisms in the result, along with future considerations for Exploration Missions (EM) are also addressed.

  11. Orion Exploration Flight Test-l (EFT -1) Absolute Navigation Design

    NASA Technical Reports Server (NTRS)

    Sud, Jastesh; Gay, Robert; Holt, Greg; Zanetti, Renato

    2014-01-01

    Scheduled to launch in September 2014 atop a Delta IV Heavy from the Kennedy Space Center, the Orion Multi-Purpose-Crew-Vehicle (MPCV's) maiden flight dubbed "Exploration Flight Test -1" (EFT-1) intends to stress the system by placing the uncrewed vehicle on a high-energy parabolic trajectory replicating conditions similar to those that would be experienced when returning from an asteroid or a lunar mission. Unique challenges associated with designing the navigation system for EFT-1 are presented in the narrative with an emphasis on how redundancy and robustness influenced the architecture. Two Inertial Measurement Units (IMUs), one GPS receiver and three barometric altimeters (BALTs) comprise the navigation sensor suite. The sensor data is multiplexed using conventional integration techniques and the state estimate is refined by the GPS pseudorange and deltarange measurements in an Extended Kalman Filter (EKF) that employs the UDUT decomposition approach. The design is substantiated by simulation results to show the expected performance.

  12. EFT (Emotional Freedom Techniques) and Resiliency in Veterans at Risk for PTSD: A Randomized Controlled Trial.

    PubMed

    Church, Dawson; Sparks, Terry; Clond, Morgan

    2016-01-01

    Prior research indicates elevated but subclinical posttraumatic stress disorder (PTSD) symptoms as a risk factor for a later diagnosis of PTSD. This study examined the progression of symptoms in 21 subclinical veterans. Participants were randomized into a treatment as usual (TAU) wait-list group and an experimental group, which received TAU plus six sessions of clinical emotional freedom techniques (EFT). Symptoms were assessed using the PCL-M (Posttraumatic Checklist-Military) on which a score of 35 or higher indicates increased risk for PTSD. The mean pretreatment score of participants was 39 ± 8.7, with no significant difference between groups. No change was found in the TAU group during the wait period. Afterward, the TAU group received an identical clinical EFT protocol. Posttreatment groups were combined for analysis. Scores declined to a mean of 25 (-64%, P < .0001). Participants maintained their gains, with mean three-month and six-month follow-up PCL-M scores of 27 (P < .0001). Similar reductions were noted in the depth and breadth of psychological conditions such as anxiety. A Cohen's d = 1.99 indicates a large treatment effect. Reductions in traumatic brain injury symptoms (P = .045) and insomnia (P = .004) were also noted. Symptom improvements were similar to those assessed in studies of PTSD-positive veterans. EFT may thus be protective against an increase in symptoms and a later PTSD diagnosis. As a simple and quickly learned self-help method, EFT may be a clinically useful element of a resiliency program for veterans and active-duty warriors. PMID:27543343

  13. Chiral sensing by nonchiral tetrapyrroles.

    PubMed

    Labuta, Jan; Hill, Jonathan P; Ishihara, Shinsuke; Hanyková, Lenka; Ariga, Katsuhiko

    2015-03-17

    host Bz2OxP that undergoes 1:1 host-guest interactions, cannot be protonated (and so does not suffer drawbacks due to tautomeric processes), and can interact solely through hydrogen bonding with a much wider range of analyte types, including acids, esters, amines (including amino acid derivatives), and ketones, for the determination of their ee at room temperature. Chiral sensing, in this case, can be understood by considering the breakdown of the host's symmetry when it interacts with a chiral guest under fast exchange. Furthermore, chirality discrimination (i.e., which is the major enantiomer in a sample) can be performed by addition of a small amount of one of the known enantiomers. Adaptation of a symmetrical molecule for ee sensing presents certain intrinsic advantages, including identical binding constants of each enantiomer. Our results indicate that other symmetrical molecules might also be useful as NMR probes of enantiopurity. These systems could provide insights into important chirality principles such as majority rule, intermolecular chirality transfer, and asymmetric reactions. The Bz2OxP system is also of note from the point of view that it does not rely on the formation of diastereomers. PMID:25734700

  14. Chiral rotational spectroscopy

    NASA Astrophysics Data System (ADS)

    Cameron, Robert P.; Götte, Jörg B.; Barnett, Stephen M.

    2016-09-01

    We introduce chiral rotational spectroscopy, a technique that enables the determination of the orientated optical activity pseudotensor components BX X, BY Y, and BZ Z of chiral molecules, in a manner that reveals the enantiomeric constitution of a sample and provides an incisive signal even for a racemate. Chiral rotational spectroscopy could find particular use in the analysis of molecules that are chiral solely by virtue of their isotopic constitution and molecules with multiple chiral centers. A basic design for a chiral rotational spectrometer together with a model of its functionality is given. Our proposed technique offers the more familiar polarizability components αX X, αY Y, and αZ Z as by-products, which could see it find use even for achiral molecules.

  15. Subtractive renormalization of the NN interaction in chiral effective theory up to next-to-next-to-leading order: S waves

    SciTech Connect

    Yang, C.-J.; Elster, Ch.; Phillips, D. R.

    2009-10-15

    We extend our subtractive-renormalization method to evaluate the {sup 1}S{sub 0} and {sup 3}S{sub 1}-{sup 3}D{sub 1} NN-scattering phase shifts up to next-to-next-to-leading order (NNLO) in chiral effective theory. We show that, if energy-dependent contact terms are employed in the NN potential, the {sup 1}S{sub 0} phase shift can be obtained by carrying out two subtractions on the Lippmann-Schwinger equation. These subtractions use knowledge of the the scattering length and the {sup 1}S{sub 0} phase shift at a specific energy to eliminate the low-energy constants in the contact interaction from the scattering equation. For the J=1 coupled channel, a similar renormalization can be achieved by three subtractions that employ knowledge of the {sup 3}S{sub 1}scattering length, the {sup 3}S{sub 1} phase shift at a specific energy, and the {sup 3}S{sub 1}-{sup 3}D{sub 1} generalized scattering length. In both channels a similar method can be applied to a potential with momentum-dependent contact terms, except that in that case one of the subtractions must be replaced by a fit to one piece of experimental data. This method allows the use of arbitrarily high cutoffs in the Lippmann-Schwinger equation. We examine the NNLO S-wave phase shifts for cutoffs as large as 19 GeV and show that the presence of linear energy dependence in the NN potential creates spurious poles in the scattering amplitude. In consequence the results are in conflict with empirical data over appreciable portions of the considered cutoff range. We also identify problems with the use of cutoffs greater than 1 GeV when momentum-dependent contact interactions are employed. These problems are ameliorated, but not eliminated, by the use of spectral-function regularization for the two-pion exchange part of the NN potential.

  16. Evaluation of sulfated maltodextrin as a novel anionic chiral selector for the enantioseparation of basic chiral drugs by capillary electrophoresis.

    PubMed

    Tabani, Hadi; Mahyari, Mojtaba; Sahragard, Ali; Fakhari, Ali Reza; Shaabani, Ahmad

    2015-01-01

    Introducing a new class of chiral selectors is an interesting work and this issue is still one of the hot topics in separation science and chirality. In this study, for the first time, sulfated maltodextrin (MD) was synthesized as a new anionic chiral selector and then it was successfully applied for the enantioseparation of five basic drugs (amlodipine, hydroxyzine, fluoxetine, tolterodine, and tramadol) as model chiral compounds using CE. This chiral selector has two recognition sites: a helical structure and a sulfated group which contribute to three corresponding driving forces; inclusion complexation, electrostatic interaction, and hydrogen binding. Under the optimized condition (buffer solution: 50 mM phosphate (pH 3.0) and 2% w/v sulfated MD; applied voltage: 18 kV; temperature: 20°C), baseline enantioseparation was observed for all mentioned chiral drugs. When instead of sulfated MD neutral MD was used under the same condition, no enantioseparation was observed which means the resolution power of sulfated MD is higher than neutral MD due to the electrostatic interaction between sulfated groups and protonated chiral drugs. Also, the countercurrent mobility of negatively charged MD (sulfated MD) allows more interactions between the chiral selector and chiral drugs and this in turn results in a successful resolution for the enantiomers. Furthermore, a higher concentration of neutral MD (approximately five times) is necessary to achieve the equivalent resolution compared with the negatively charged MD.

  17. Chiral atomically thin films

    NASA Astrophysics Data System (ADS)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm–1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  18. Characterizing optical chirality

    SciTech Connect

    Bliokh, Konstantin Y.; Nori, Franco

    2011-02-15

    We examine the recently introduced measure of chirality of a monochromatic optical field [Y. Tang and A. E. Cohen, Phys. Rev. Lett. 104, 163901 (2010)] using the momentum (plane-wave) representation and helicity basis. Our analysis clarifies the physical meaning of the measure of chirality and unveils its close relation to the polarization helicity, spin angular momentum, energy density, and Poynting energy flow. We derive the operators of the optical chirality and of the corresponding chiral momentum, which acquire remarkably simple forms in the helicity representation.

  19. Chiral atomically thin films

    NASA Astrophysics Data System (ADS)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm-1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  20. Achiral flexible liquid crystal trimers exhibiting chiral conglomerates.

    PubMed

    Sasaki, Haruna; Takanishi, Yoichi; Yamamoto, Jun; Yoshizawa, Atsushi

    2016-04-14

    Chiral conglomerates of domains with opposite handedness have attracted much attention from researchers. We prepared a homologous series of achiral liquid crystal trimers in which two phenylpyrimidine units and one biphenyl unit were connected via flexible methylene spacers. We investigated their phase transition behaviour. Some trimers possessing odd-numbered spacers were found to exhibit a nematic phase and a dark chiral conglomerate phase possessing a layered structure. The chiral characteristics were confirmed by uncrossing the polarizers in opposite directions. The layer spacing detected using X-ray diffraction was about 80% of the molecular length. The structure-property relations indicate that intermolecular interactions cause a conformational change in the trimers possessing flexible odd-numbered methylene spacers to form helical conformers with axial chirality, which might induce chiral segregation and layer deformation to drive the chiral conglomerates.

  1. Supramolecular chirality in self-assembled peptide amphiphile nanostructures.

    PubMed

    Garifullin, Ruslan; Guler, Mustafa O

    2015-08-11

    Induced supramolecular chirality was investigated in the self-assembled peptide amphiphile (PA) nanosystems. Having shown that peptide chirality can be transferred to the covalently-attached achiral pyrene moiety upon PA self-assembly, the chiral information is transferred to molecular pyrene via weak noncovalent interactions. In the first design of a supramolecular chiral system, the chromophore was covalently attached to a peptide sequence (VVAGH) via an ε-aminohexanoic acid spacer. Covalent attachment yielded a PA molecule self-assembling into nanofibers. In the second design, the chromophore was encapsulated within the hydrophobic core of self-assembled nanofibers of another PA consisting of the same peptide sequence attached to lauric acid. We observed that supramolecular chirality was induced in the chromophore by PA assembly into chiral nanostructures, whether it was covalently attached, or noncovalently bound. PMID:26146021

  2. Chiral plasmons without magnetic field

    PubMed Central

    Song, Justin C. W.; Rudner, Mark S.

    2016-01-01

    Plasmons, the collective oscillations of interacting electrons, possess emergent properties that dramatically alter the optical response of metals. We predict the existence of a new class of plasmons—chiral Berry plasmons (CBPs)—for a wide range of 2D metallic systems including gapped Dirac materials. As we show, in these materials the interplay between Berry curvature and electron–electron interactions yields chiral plasmonic modes at zero magnetic field. The CBP modes are confined to system boundaries, even in the absence of topological edge states, with chirality manifested in split energy dispersions for oppositely directed plasmon waves. We unveil a rich CBP phenomenology and propose setups for realizing them, including in anomalous Hall metals and optically pumped 2D Dirac materials. Realization of CBPs will offer a powerful paradigm for magnetic field-free, subwavelength optical nonreciprocity, in the mid-IR to terahertz range, with tunable splittings as large as tens of THz, as well as sensitive all-optical diagnostics of topological bands. PMID:27071090

  3. Chiral plasmons without magnetic field.

    PubMed

    Song, Justin C W; Rudner, Mark S

    2016-04-26

    Plasmons, the collective oscillations of interacting electrons, possess emergent properties that dramatically alter the optical response of metals. We predict the existence of a new class of plasmons-chiral Berry plasmons (CBPs)-for a wide range of 2D metallic systems including gapped Dirac materials. As we show, in these materials the interplay between Berry curvature and electron-electron interactions yields chiral plasmonic modes at zero magnetic field. The CBP modes are confined to system boundaries, even in the absence of topological edge states, with chirality manifested in split energy dispersions for oppositely directed plasmon waves. We unveil a rich CBP phenomenology and propose setups for realizing them, including in anomalous Hall metals and optically pumped 2D Dirac materials. Realization of CBPs will offer a powerful paradigm for magnetic field-free, subwavelength optical nonreciprocity, in the mid-IR to terahertz range, with tunable splittings as large as tens of THz, as well as sensitive all-optical diagnostics of topological bands. PMID:27071090

  4. Spontaneous chiral symmetry breaking in collective active motion

    NASA Astrophysics Data System (ADS)

    Breier, Rebekka E.; Selinger, Robin L. B.; Ciccotti, Giovanni; Herminghaus, Stephan; Mazza, Marco G.

    2016-02-01

    Chiral symmetry breaking is ubiquitous in biological systems, from DNA to bacterial suspensions. A key unresolved problem is how chiral structures may spontaneously emerge from achiral interactions. We study a simple model of active swimmers in three dimensions that effectively incorporates hydrodynamic interactions. We perform large-scale molecular dynamics simulations (up to 106 particles) and find long-lived metastable collective states that exhibit chiral organization although the interactions are achiral. We elucidate under which conditions these chiral states will emerge and grow to large scales. To explore the complex phase space available to the system, we perform nonequilibrium quenches on a one-dimensional Lebwohl-Lasher model with periodic boundary conditions to study the likelihood of formation of chiral structures.

  5. Multistep hierarchical self-assembly of chiral nanopore arrays

    PubMed Central

    Kim, Hanim; Lee, Sunhee; Shin, Tae Joo; Korblova, Eva; Walba, David M.; Clark, Noel A.; Lee, Sang Bok; Yoon, Dong Ki

    2014-01-01

    A series of simple hierarchical self-assembly steps achieve self-organization from the centimeter to the subnanometer-length scales in the form of square-centimeter arrays of linear nanopores, each one having a single chiral helical nanofilament of large internal surface area and interfacial interactions based on chiral crystalline molecular arrangements. PMID:25246585

  6. Elucidation of the mechanism of chiral selectivity in diastereomeric salt formation using organic solvent nanofiltration.

    PubMed

    Ghazali, Nazlee F; Patterson, Darrell A; Livingston, Andrew G

    2004-04-21

    Organic solvent nanofiltration (OSN) was used to investigate the mechanism of chiral selectivity in diastereomeric salt formation of alpha-phenylethylamine with D-tartaric acid and di-p-toluoyl-D-tartaric acid as resolving agents; results indicate that for these systems chiral selectivity occurs only upon crystallisation and chiral interactions in solution were negligible. PMID:15069495

  7. Neutral and ionic platinum compounds containing a cyclometallated chiral primary amine: synthesis, antitumor activity, DNA interaction and topoisomerase I-cathepsin B inhibition.

    PubMed

    Albert, Joan; Bosque, Ramon; Crespo, Margarita; Granell, Jaume; López, Concepción; Martín, Raquel; González, Asensio; Jayaraman, Anusha; Quirante, Josefina; Calvis, Carme; Badía, Josefa; Baldomà, Laura; Font-Bardia, Mercè; Cascante, Marta; Messeguer, Ramon

    2015-08-14

    The synthesis and preliminary biological evaluation of neutral and cationic platinum derivatives of chiral 1-(1-naphthyl)ethylamine are reported, namely cycloplatinated neutral complexes [PtCl{(R or S)-NH(2)CH(CH(3))C(10)H(6)}(L)] [L = SOMe(2) ( 1-R or 1-S ), L = PPh(3) (2-R or 2-S), L = P(4-FC(6)H(4))(3) (3-R), L = P(CH(2))(3)N(3)(CH(2))(3) (4-R)], cycloplatinated cationic complexes [Pt{(R)-NH(2)CH(CH(3))C(10)H(6)}{L}]Cl [L = Ph(2)PCH(2)CH(2)PPh(2) (5-R), L = (C(6)F(5))(2)PCH(2)CH(2)P(C(6)F(5))(2) (6-R)] and the Pt(ii) coordination compound trans-[PtCl(2){(R)-NH(2)CH(CH(3))C(10)H(6)}(2)] (7-R). The X-ray molecular structure of 7-R is reported. The cytotoxic activity against a panel of human adenocarcinoma cell lines (A-549 lung, MDA-MB-231 and MCF-7 breast, and HCT-116 colon), cell cycle arrest and apoptosis, DNA interaction, topoisomerase I and cathepsin B inhibition, and Pt cell uptake of the studied compounds are presented. Remarkable cytotoxicity was observed for most of the synthesized Pt(ii) compounds regardless of (i) the absolute configuration R or S, and (ii) the coordinated/cyclometallated (neutral or cationic) nature of the complexes. The most potent compound 2-R (IC(50) = 270 nM) showed a 148-fold increase in potency with regard to cisplatin in HCT-116 colon cancer cells. Preliminary biological results point out to different biomolecular targets for the investigated compounds. Neutral cyclometallated complexes 1-R and 2-R, modify the DNA migration as cisplatin, cationic platinacycle 5-R was able to inhibit topoisomerase I-promoted DNA supercoiling, and Pt(ii) coordination compound 7-R turned out to be the most potent inhibitor of cathepsin B. Induction of G-1 phase ( 2-R and 5-R ), and S and G-2 phases (6-R) arrests are related to the antiproliferative activity of some representative compounds upon A-549 cells. Induction of apoptosis is also observed for 2-R and 6-R.

  8. Chiral geometry in multiple chiral doublet bands

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Chen, Qibo

    2016-02-01

    The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with . The energy spectra, electromagnetic transition probabilities B(M1) and B(E2), angular momenta, and K-distributions are studied. It is demonstrated that the chirality still remains not only in the yrast and yrare bands, but also in the two higher excited bands when γ deviates from 30°. The chiral geometry relies significantly on γ, and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands. Supported by Plan Project of Beijing College Students’ Scientific Research and Entrepreneurial Action, Major State 973 Program of China (2013CB834400), National Natural Science Foundation of China (11175002, 11335002, 11375015, 11461141002), National Fund for Fostering Talents of Basic Science (NFFTBS) (J1103206), Research Fund for Doctoral Program of Higher Education (20110001110087) and China Postdoctoral Science Foundation (2015M580007)

  9. Molecular-level Design of Heterogeneous Chiral Catalysts

    SciTech Connect

    Gellman, Andrew John; Sholl, David S.; Tysoe, Wilfred T.; Zaera, Francisco

    2013-04-28

    Understanding and controlling selectivity is one of the key challenges in heterogeneous catalysis. Among problems in catalytic selectivity enantioselectivity is perhaps the most the most challenging. The primary goal of the project on “Molecular-level Design of Heterogeneous Chiral Catalysts” is to understand the origins of enantioselectivity on chiral heterogeneous surfaces and catalysts. The efforts of the project team include preparation of chiral surfaces, characterization of chiral surfaces, experimental detection of enantioselectivity on such surfaces and computational modeling of the interactions of chiral probe molecules with chiral surfaces. Over the course of the project period the team of PI’s has made some of the most detailed and insightful studies of enantioselective chemistry on chiral surfaces. This includes the measurement of fundamental interactions and reaction mechanisms of chiral molecules on chiral surfaces and leads all the way to rationale design and synthesis of chiral surfaces and materials for enantioselective surface chemistry. The PI’s have designed and prepared new materials for enantioselective adsorption and catalysis. Naturally Chiral Surfaces • Completion of a systematic study of the enantiospecific desorption kinetics of R-3-methylcyclohexanone (R-3-MCHO) on 9 achiral and 7 enantiomeric pairs of chiral Cu surfaces with orientations that span the stereographic triangle. • Discovery of super-enantioselective tartaric acid (TA) and aspartic acid (Asp) decomposition as a result of a surface explosion mechanism on Cu(643)R&S. Systematic study of super-enantiospecific TA and Asp decomposition on five enantiomeric pairs of chiral Cu surfaces. • Initial observation of the enantiospecific desorption of R- and S-propylene oxide (PO) from Cu(100) imprinted with {3,1,17} facets by L-lysine adsorption. Templated Chiral Surfaces • Initial observation of the enantiospecific desorption of R- and S-PO from Pt(111) and Pd(111

  10. Subtractive Renormalization Group Invariance: Pionless EFT at NLO

    SciTech Connect

    Timoteo, Varese S.; Szpigel, Sergio; Duraes, Francisco O.

    2010-11-12

    We show some results concerning the renormalization group (RG) invariance of the nucleon-nucleon (NN) interaction in pionless effective field theory at next-to-leading order (NLO), using a non-relativistic Callan-Symanzik equation (NRCS) for the driving term of the Lippmann-Schwinger (LS) equation with three recursive subtractions. The phase-shifts obtained for the RG evolved potential are same as those for the original potential, apart from relative differences of order 10{sup -15}.

  11. Objects of Maximum Electromagnetic Chirality

    NASA Astrophysics Data System (ADS)

    Fernandez-Corbaton, Ivan; Fruhnert, Martin; Rockstuhl, Carsten

    2016-07-01

    We introduce a definition of the electromagnetic chirality of an object and show that it has an upper bound. Reciprocal objects attain the upper bound if and only if they are transparent for all the fields of one polarization handedness (helicity). Additionally, electromagnetic duality symmetry, i.e., helicity preservation upon interaction, turns out to be a necessary condition for reciprocal objects to attain the upper bound. We use these results to provide requirements for the design of such extremal objects. The requirements can be formulated as constraints on the polarizability tensors for dipolar objects or on the material constitutive relations for continuous media. We also outline two applications for objects of maximum electromagnetic chirality: a twofold resonantly enhanced and background-free circular dichroism measurement setup, and angle-independent helicity filtering glasses. Finally, we use the theoretically obtained requirements to guide the design of a specific structure, which we then analyze numerically and discuss its performance with respect to maximal electromagnetic chirality.

  12. Magnetic fields and chiral asymmetry in the early hot universe

    NASA Astrophysics Data System (ADS)

    Sydorenko, Maksym; Tomalak, Oleksandr; Shtanov, Yuri

    2016-10-01

    In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of `inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.

  13. Mitochondrial EFTs defects in juvenile-onset Leigh disease, ataxia, neuropathy, and optic atrophy

    PubMed Central

    Ahola, Sofia; Isohanni, Pirjo; Euro, Liliya; Brilhante, Virginia; Palotie, Aarno; Pihko, Helena; Lönnqvist, Tuula; Lehtonen, Tanita; Laine, Jukka; Tyynismaa, Henna

    2014-01-01

    Objective: We report novel defects of mitochondrial translation elongation factor Ts (EFTs), with high carrier frequency in Finland and expand the manifestations of this disease group from infantile cardiomyopathy to juvenile neuropathy/encephalopathy disorders. Methods: DNA analysis, whole-exome analysis, protein biochemistry, and protein modeling. Results: We used whole-exome sequencing to find the genetic cause of infantile-onset mitochondrial cardiomyopathy, progressing to juvenile-onset Leigh syndrome, neuropathy, and optic atrophy in 2 siblings. We found novel compound heterozygous mutations, c.944G>A [p.C315Y] and c.856C>T [p.Q286X], in the TSFM gene encoding mitochondrial EFTs. The same p.Q286X variant was found as compound heterozygous with a splice site change in a patient from a second family, with juvenile-onset optic atrophy, peripheral neuropathy, and ataxia. Our molecular modeling predicted the coding-region mutations to cause protein instability, which was experimentally confirmed in cultured patient cells, with mitochondrial translation defect and lacking EFTs. Only a single TSFM mutation has been previously described in different populations, leading to an infantile fatal multisystem disorder with cardiomyopathy. Sequence data from 35,000 Finnish population controls indicated that the heterozygous carrier frequency of p.Q286X change was exceptionally high in Finland, 1:80, but no homozygotes were found in the population, in our mitochondrial disease patient collection, or in an intrauterine fetal death material, suggesting early developmental lethality of the homozygotes. Conclusions: We show that in addition to early-onset cardiomyopathy, TSFM mutations should be considered in childhood and juvenile encephalopathies with optic and/or peripheral neuropathy, ataxia, or Leigh disease. PMID:25037205

  14. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    NASA Astrophysics Data System (ADS)

    Pelayo, José de Jesús; Valencia, Israel; Díaz, Gabriela; López-Lozano, Xóchitl; Garzón, Ignacio L.

    2015-12-01

    The interaction of biological molecules like chiral amino acids with chiral metal clusters is becoming an interesting and active field of research because of its potential impact in, for example, chiral molecular recognition phenomena. In particular, the enantiospecific adsorption (EA) of cysteine (Cys) on a chiral Au55 cluster was theoretically predicted a few years ago. In this work, we present theoretical results, based on density functional theory, of the EA of non-zwitterionic cysteine interacting with the C3-Au34 chiral cluster, which has been experimentally detected in gas phase, using trapped ion electron diffraction. Our results show that, indeed, the adsorption energy of the amino acid depends on which enantiomers participate in the formation Cys-Au34 chiral complex. EA was obtained in the adsorption modes where both the thiol, and the thiol-amino functional groups of Cys are adsorbed on low-coordinated sites of the metal cluster surface. Similarly to what was obtained for the Cys-Au55 chiral complex, in the present work, it is found that the EA is originated from the different strength and location of the bond between the COOH functional group and surface Au atoms of the Au34 chiral cluster. Calculations of the vibrational spectrum for the different Cys-Au34 diastereomeric complexes predict the existence of a vibro-enantiospecific effect, indicating that the vibrational frequencies of the adsorbed amino acid depend on its handedness.

  15. The covariant chiral ring

    NASA Astrophysics Data System (ADS)

    Bourget, Antoine; Troost, Jan

    2016-03-01

    We construct a covariant generating function for the spectrum of chiral primaries of symmetric orbifold conformal field theories with N = (4 , 4) supersymmetry in two dimensions. For seed target spaces K3 and T 4, the generating functions capture the SO(21) and SO(5) representation theoretic content of the chiral ring respectively. Via string dualities, we relate the transformation properties of the chiral ring under these isometries of the moduli space to the Lorentz covariance of perturbative string partition functions in flat space.

  16. Synthesis of Chiral Cyclopentenones.

    PubMed

    Simeonov, Svilen P; Nunes, João P M; Guerra, Krassimira; Kurteva, Vanya B; Afonso, Carlos A M

    2016-05-25

    The cyclopentenone unit is a very powerful synthon for the synthesis of a variety of bioactive target molecules. This is due to the broad diversity of chemical modifications available for the enone structural motif. In particular, chiral cyclopentenones are important precursors in the asymmetric synthesis of target chiral molecules. This Review provides an overview of reported methods for enantioselective and asymmetric syntheses of cyclopentenones, including chemical and enzymatic resolution, asymmetric synthesis via Pauson-Khand reaction, Nazarov cyclization and organocatalyzed reactions, asymmetric functionalization of the existing cyclopentenone unit, and functionalization of chiral building blocks. PMID:27101336

  17. Polar Superhelices in Ferroelectric Chiral Nanosprings

    NASA Astrophysics Data System (ADS)

    Shimada, Takahiro; Lich, Le Van; Nagano, Koyo; Wang, Jian-Shan; Wang, Jie; Kitamura, Takayuki

    2016-10-01

    Topological objects of nontrivial spin or dipolar field textures, such as skyrmions, merons, and vortices, interacting with applied external fields in ferroic materials are of great scientific interest as an intriguing playground of unique physical phenomena and novel technological paradigms. The quest for new topological configurations of such swirling field textures has primarily been done for magnets with Dzyaloshinskii-Moriya interactions, while the absence of such intrinsic chiral interactions among electric dipoles left ferroelectrics aside in this quest. Here, we demonstrate that a helical polarization coiled into another helix, namely a polar superhelix, can be extrinsically stabilized in ferroelectric nanosprings. The interplay between dipolar interactions confined in the chiral geometry and the complex strain field of mixed bending and twisting induces the superhelical configuration of electric polarization. The geometrical structure of the polar superhelix gives rise to electric chiralities at two different length scales and the coexistence of three order parameters, i.e., polarization, toroidization, and hypertoroidization, both of which can be manipulated by homogeneous electric and/or mechanical fields. Our work therefore provides a new geometrical configuration of swirling dipolar fields, which offers the possibility of multiple order-parameters, and electromechanically controllable dipolar chiralities and associated electro-optical responses.

  18. Polar Superhelices in Ferroelectric Chiral Nanosprings

    PubMed Central

    Shimada, Takahiro; Lich, Le Van; Nagano, Koyo; Wang, Jian-Shan; Wang, Jie; Kitamura, Takayuki

    2016-01-01

    Topological objects of nontrivial spin or dipolar field textures, such as skyrmions, merons, and vortices, interacting with applied external fields in ferroic materials are of great scientific interest as an intriguing playground of unique physical phenomena and novel technological paradigms. The quest for new topological configurations of such swirling field textures has primarily been done for magnets with Dzyaloshinskii-Moriya interactions, while the absence of such intrinsic chiral interactions among electric dipoles left ferroelectrics aside in this quest. Here, we demonstrate that a helical polarization coiled into another helix, namely a polar superhelix, can be extrinsically stabilized in ferroelectric nanosprings. The interplay between dipolar interactions confined in the chiral geometry and the complex strain field of mixed bending and twisting induces the superhelical configuration of electric polarization. The geometrical structure of the polar superhelix gives rise to electric chiralities at two different length scales and the coexistence of three order parameters, i.e., polarization, toroidization, and hypertoroidization, both of which can be manipulated by homogeneous electric and/or mechanical fields. Our work therefore provides a new geometrical configuration of swirling dipolar fields, which offers the possibility of multiple order-parameters, and electromechanically controllable dipolar chiralities and associated electro-optical responses. PMID:27713540

  19. Spintronics: Chiral damping

    PubMed Central

    Kim, Kyoung-Whan; Lee, Hyun-Woo

    2016-01-01

    The analysis of the magnetic domain wall motion in a nanostructured magnetic system with strong spin-orbit coupling shows that the energy dissipation can be chiral when the inversion symmetry is broken. PMID:26906956

  20. Nonlinear chiral transport phenomena

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei; Ishii, Takeaki; Pu, Shi; Yamamoto, Naoki

    2016-06-01

    We study the nonlinear responses of relativistic chiral matter to the external fields such as the electric field E , gradients of temperature and chemical potential, ∇T and ∇μ . Using the kinetic theory with Berry curvature corrections under the relaxation time approximation, we compute the transport coefficients of possible new electric currents that are forbidden in usual chirally symmetric matter but are allowed in chirally asymmetric matter by parity. In particular, we find a new type of electric current proportional to ∇μ ×E due to the interplay between the effects of the Berry curvature and collisions. We also derive an analog of the "Wiedemann-Franz" law specific for anomalous nonlinear transport in relativistic chiral matter.

  1. Four-nucleon force in chiral effective field theory

    SciTech Connect

    Evgeny Epelbaum

    2005-10-25

    We derive the leading contribution to the four--nucleon force within the framework of chiral effective field theory. It is governed by the exchange of pions and the lowest--order nucleon--nucleon contact interaction and includes effects due to the nonlinear pion--nucleon couplings and the pion self interactions constrained by the chiral symmetry of QCD. The resulting 4NF does not contain any unknown parameters and can be tested in future few--and many--nucleon studies.

  2. The quest for chirality

    SciTech Connect

    Bonner, W.A.

    1996-07-01

    The indispensable role played by homochirality and chiral homogeneity in the self-replication of crucial biomolecules is stressed, with the conclusion that life could neither exist nor originate without these chiral molecular attributes. Hypotheses historically proposed for the origin of chiral molecules on Earth are reviewed, including biogenic theories as well as abiotic theories embracing both indeterminate and determinate mechanisms. Indeterminate mechanisms, including autocatalytic symmetry breaking, asymmetric adsorption on quartz and clay minerals, and asymmetric syntheses in chiral crystals, are discussed and evaluated in the context of the prebiotic environment. Abiotic determinate mechanisms based on electric, magnetic and gravitational fields, on circularly polarized light (CPL), and on parity violation effects are summarized, with the emphasis that only CPL has proved practicable experimentally, but that it would be implausible on the primitive Earth. Mechanisms for the amplification of small, indigenous enantiomeric excesses are discussed, with one involving the partial polymerization of amino acids and the partial hydrolysis of polypeptides suggested as potentially viable prebiotically. Aspects of the turbulent, chirality-destructive primeval environment are described, with the conclusion that all of the above mechanisms for the {ital terrestrial} prebiotic origin of chirality would be non-viable, and that an alternative extraterrestrial source for the accumulation of chiral molecules on primitive Earth must have been operative. A scenario for this is outlined, in which we postulate that asymmetric photolysis of the organic mantles on interstellar grains in molecular clouds by circularly polarized ultraviolet synchrotron radiation from the neutron star remnants of supernovae produces chiral molecules in the grain mantles. (Abstract Truncated)

  3. Orion Exploration Flight Test 1 (EFT-1) Best Estimated Trajectory Development

    NASA Technical Reports Server (NTRS)

    Holt, Greg N.; Brown, Aaron

    2016-01-01

    The Orion Exploration Flight Test 1 (EFT-1) mission successfully flew on Dec 5, 2014 atop a Delta IV Heavy launch vehicle. The goal of Orions maiden flight was to stress the system by placing an uncrewed vehicle on a high-energy trajectory replicating conditions similar to those that would be experienced when returning from an asteroid or a lunar mission. The Orion navigation team combined all trajectory data from the mission into a Best Estimated Trajectory (BET) product. There were significant challenges in data reconstruction and many lessons were learned for future missions. The team used an estimation filter incorporating radar tracking, onboard sensors (Global Positioning System and Inertial Measurement Unit), and day-of-flight weather balloons to evaluate the true trajectory flown by Orion. Data was published for the entire Orion EFT-1 flight, plus objects jettisoned during entry such as the Forward Bay Cover. The BET customers include approximately 20 disciplines within Orion who will use the information for evaluating vehicle performance and influencing future design decisions.

  4. The significance of chirality in drug design and development.

    PubMed

    Brooks, W H; Guida, W C; Daniel, K G

    2011-01-01

    Proteins are often enantioselective towards their binding partners. When designing small molecules to interact with these targets, one should consider stereoselectivity. As considerations for exploring structure space evolve, chirality is increasingly important. Binding affinity for a chiral drug can differ for diastereomers and between enantiomers. For the virtual screening and computational design stage of drug development, this problem can be compounded by incomplete stereochemical information in structure libraries leading to a "coin toss" as to whether or not the "ideal" chiral structure is present. Creating every stereoisomer for each chiral compound in a structure library leads to an exponential increase in the number of structures resulting in potentially unmanageable file sizes and screening times. Therefore, only key chiral structures, enantiomeric pairs based on relative stereochemistry need be included, and lead to a compromise between exploration of chemical space and maintaining manageable libraries. In clinical environments, enantiomers of chiral drugs can have reduced, no, or even deleterious effects. This underscores the need to avoid mixtures of compounds and focus on chiral synthesis. Governmental regulations emphasizing the need to monitor chirality in drug development have increased. The United States Food and Drug Administration issued guidelines and policies in 1992 concerning the development of chiral compounds. These guidelines require that absolute stereochemistry be known for compounds with chiral centers and that this information should be established early in drug development in order that the analysis can be considered valid. From exploration of structure space to governmental regulations it is clear that the question of chirality in drug design is of vital importance. PMID:21291399

  5. The significance of chirality in drug design and development.

    PubMed

    Brooks, W H; Guida, W C; Daniel, K G

    2011-01-01

    Proteins are often enantioselective towards their binding partners. When designing small molecules to interact with these targets, one should consider stereoselectivity. As considerations for exploring structure space evolve, chirality is increasingly important. Binding affinity for a chiral drug can differ for diastereomers and between enantiomers. For the virtual screening and computational design stage of drug development, this problem can be compounded by incomplete stereochemical information in structure libraries leading to a "coin toss" as to whether or not the "ideal" chiral structure is present. Creating every stereoisomer for each chiral compound in a structure library leads to an exponential increase in the number of structures resulting in potentially unmanageable file sizes and screening times. Therefore, only key chiral structures, enantiomeric pairs based on relative stereochemistry need be included, and lead to a compromise between exploration of chemical space and maintaining manageable libraries. In clinical environments, enantiomers of chiral drugs can have reduced, no, or even deleterious effects. This underscores the need to avoid mixtures of compounds and focus on chiral synthesis. Governmental regulations emphasizing the need to monitor chirality in drug development have increased. The United States Food and Drug Administration issued guidelines and policies in 1992 concerning the development of chiral compounds. These guidelines require that absolute stereochemistry be known for compounds with chiral centers and that this information should be established early in drug development in order that the analysis can be considered valid. From exploration of structure space to governmental regulations it is clear that the question of chirality in drug design is of vital importance.

  6. Chiral charge erasure via thermal fluctuations of magnetic helicity

    NASA Astrophysics Data System (ADS)

    Long, Andrew J.; Sabancilar, Eray

    2016-05-01

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ gtrsim 1/(αμ5), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ5 parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δScript H ~ λT and τ ~ αλ3T2 for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t ~ T3/(α5μ54) until it reaches an equilibrium value Script H ~ μ5T2/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ5 < T/α, this avenue for chiral charge erasure is found to be slower than the chiral magnetic effect for which t ~ T/(α3μ52). This mechanism for chiral charge erasure can be important for the hypercharge sector of the Standard Model as well as extensions including U(1) gauge interactions, such as asymmetric dark matter models.

  7. Chiral Recognition Mechanisms in Enantiomers Separations: A General View

    NASA Astrophysics Data System (ADS)

    Berthod, Alain

    In 1858, Louis Pasteur, the first to accomplish the separation of two enantiomers wrote: “Most natural organic products, the essential products of life, are asymmetric and possess such asymmetry that they are not superimposable on their image. This establishes perhaps the only well-marked line of demarcation that can at present be drawn between the chemistry of dead matter and the chemistry of living matter.” Enantiomers have exactly the same properties in isotropic conditions. They behave differently only in anisotropic conditions. Chiral-chiral interactions are needed for enantiomeric separations. The fundamental mechanisms for chiral separations are listed along with the commercially available chiral selectors. Two chemometric examples are commented: one on quantitative structure enantioselectivity relationship and the second one on linear solvation energy relationships. It is shown that the solvents used in the mobile phase may play the most critical role in the chiral mechanism.

  8. Chirality: a blueprint for the future.

    PubMed

    Burke, D; Henderson, D J

    2002-04-01

    The chirality that is inherent in the enzyme systems of living organisms results in an abundance of enantiopure organic molecules in the living world. In addition to the optical properties first noticed by Pasteur, stereospecific interactions at recognition sites result in differences in both biological and toxicological effects. This fact underlies the continuing growth in chiral chemistry, rooted as it is in fundamental biochemistry. The pharmaceutical industry has undergone a strategic shift and embraced the wide spectrum of asymmetrical synthetic methods now available. The use of these processes in developmental synthesis and large-scale manufacturing has provided new challenges in drug discovery, motivated by a desire to improve industrial efficacy and decrease the time from the conception of a new drug to the market. The economic impact of the industrial production of chiral drugs is now huge--more than 50% of the 500 top-selling drugs were single-enantiomers in 1997. Sales have continued to increase by more than 20% for the past 6 yr and worldwide annual sales of enantiomeric drugs exceeded US$100 billion for the first time in the year 2000, chiral drugs representing close to one-third of all sales worldwide. While some 'chiral switches' may be of less apparent benefit, or indeed detrimental in some cases, encouragement by the regulatory agencies and the ability to extend the life cycle of a drug coming off patent promotes the trend. However, it may turn out to be the ability to provide chiral templates, and thereby attack the key targets of selectivity and specificity, that will lead to the greatest benefits. Research into new chemical entities that can interact specifically with enzyme families may potentially lead to new therapies for complex disease processes. As Richards has stated, the approach is designed to create a made to measure product, rather than one off the peg.

  9. An AFM investigation of the interaction of chiral amino acids with the {l_brace}104{r_brace} face of calcite

    SciTech Connect

    Orme, C A; Noy, A; McBride, M T; DeYoreo, J J

    2000-10-01

    In biomineralized tissue, Nature often uses a single crystal system to form tools with widely varied form and functionality. To accomplish this, organisms have developed methods to deterministically modify and control crystal habit, commonly creating shapes with lower symmetry than is possessed by the pure crystal. In this paper we use atomic force microscopy to investigate the effect of chiral amino acids on calcite growth. We show that the atomic steps and resultant macroscopic shape exhibit a lower symmetry that reflects the chirality of the amino acid. We use this result to constrain the possible stereospecific binding sites. We argue that the change in morphology is not due to the incorporation of the amino acid, but rather that it acts like a surfactant changing the energetics of the interface. These results suggest that the conventional paradigm for understanding the geometrical and chemical aspects of biomineralization in terms of stereochemical recognition should be expanded to capture the energetic controls that determine the mechanisms of mineral modification by biomolecules.

  10. Chiral Polychlorinated Biphenyl Transport, Metabolism and Distribution - A Review

    PubMed Central

    Lehmler, Hans-Joachim; Harrad, Stuart J.; Hühnerfuss, Heinrich; Kania-Korwel, Izabela; Lee, Cindy M.; Lu, Zhe; Wong, Charles S.

    2009-01-01

    Chirality can be exploited to gain insight into enantioselective fate processes that may otherwise remain undetected because only biological, but not physical and chemical transport and transformation processes in an achiral environment will change enantiomer compositions. This review provides an in-depth overview of the application of chirality to the study of chiral polychlorinated biphenyls (PCBs), an important group of legacy pollutants. Like other chiral compounds, individual PCB enantiomers may interact enantioselectively (or enantiospecifically) with chiral macromolecules, such as cytochrome P-450 enzymes or ryanodine receptors, leading to differences in their toxicological effects and the enantioselective formation of chiral biotransformation products. Species and congener-specific enantiomer enrichment has been demonstrated in environmental compartments, wildlife and mammals, including humans, typically due to a complex combination of biotransformation processes and uptake via the diet by passive diffusion. Changes in the enantiomer composition of chiral PCBs in the environment have been used to understand complex aerobic and anaerobic microbial transformation pathways, to delineate and quantify PCB sources and transport in the environment, to gain insight into the biotransformation of PCBs in aquatic food webs, and to investigate the enantioselective disposition of PCBs and their methylsulfonyl PCBs metabolites in rodents. Overall, changes in chiral signatures are powerful, but currently underutilized tools for studies of environmental and biological processes of PCBs. PMID:20384371

  11. Chiral magnetism at oxide interfaces

    NASA Astrophysics Data System (ADS)

    Randeria, Mohit

    2014-03-01

    There are tantalizing hints of magnetism at the n-type LaAlO3/SrTiO3 interface, but the experimental evidence remains controversial in view of some of the differences between different samples and probes. I will argue that if magnetism exists at interfaces, symmetry arguments imply chiral interactions that lead to a spiral ground state in zero external field and skyrmion crystals for H ≠ 0 . I will next present a microscopic model that provides a possible mechanism for the formation of local moments. I will show that the coupling of these moments to itinerant electrons leads to ferromagnetic double exchange together with Dzyaloshinskii-Moriya (DM) interactions and an easy-plane ``compass'' anisotropy, which arise from Rashba spin-orbit coupling (SOC) due to the lack of inversion symmetry at the interface. The compass term, often ignored in the literature on chiral magnetism, is shown to play a crucial role in determining the magnetic ground state. I will compare our results with existing torque magnetometry data on LAO/STO and try to reconcile it with scanning SQUID magnetometry. Finally, I will present the phase diagram in a field and show that easy-plane anisotropy stabilizes an unexpectedly large skyrmion crystal phase and describe its properties. (Work done in collaboration with Sumilan Banerjee, Onur Erten, Daniel Kestner and James Rowland). Supported by DOE-BES DE-SC0005035, NSF-DMR-1006532 and NSF MRSEC DMR-0820414.

  12. 45 CFR 162.1602 - Standards for health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Standards for health care electronic funds... REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1602 Standards for health... following standards: (a) For the period from October 16, 2003 through March 16, 2009: Health care claims...

  13. 45 CFR 162.1602 - Standards for health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Standards for health care electronic funds... REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1602 Standards for health... following standards: (a) For the period from October 16, 2003 through March 16, 2009: Health care claims...

  14. 45 CFR 162.1602 - Standards for health care electronic funds transfers (EFT) and remittance advice transaction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Standards for health care electronic funds... REQUIREMENTS Health Care Electronic Funds Transfers (EFT) and Remittance Advice § 162.1602 Standards for health... following standards: (a) For the period from October 16, 2003 through March 16, 2009: Health care claims...

  15. Chiral light intrinsically couples to extrinsic/pseudo-chiral metasurfaces made of tilted gold nanowires

    NASA Astrophysics Data System (ADS)

    Belardini, Alessandro; Centini, Marco; Leahu, Grigore; Hooper, David C.; Li Voti, Roberto; Fazio, Eugenio; Haus, Joseph W.; Sarangan, Andrew; Valev, Ventsislav K.; Sibilia, Concita

    2016-08-01

    Extrinsic or pseudo-chiral (meta)surfaces have an achiral structure, yet they can give rise to circular dichroism when the experiment itself becomes chiral. Although these surfaces are known to yield differences in reflected and transmitted circularly polarized light, the exact mechanism of the interaction has never been directly demonstrated. Here we present a comprehensive linear and nonlinear optical investigation of a metasurface composed of tilted gold nanowires. In the linear regime, we directly demonstrate the selective absorption of circularly polarised light depending on the orientation of the metasurface. In the nonlinear regime, we demonstrate for the first time how second harmonic generation circular dichroism in such extrinsic/pseudo-chiral materials can be understood in terms of effective nonlinear susceptibility tensor elements that switch sign depending on the orientation of the metasurface. By providing fundamental understanding of the chiroptical interactions in achiral metasurfaces, our work opens up new perspectives for the optimisation of their properties.

  16. Chiral light intrinsically couples to extrinsic/pseudo-chiral metasurfaces made of tilted gold nanowires.

    PubMed

    Belardini, Alessandro; Centini, Marco; Leahu, Grigore; Hooper, David C; Li Voti, Roberto; Fazio, Eugenio; Haus, Joseph W; Sarangan, Andrew; Valev, Ventsislav K; Sibilia, Concita

    2016-01-01

    Extrinsic or pseudo-chiral (meta)surfaces have an achiral structure, yet they can give rise to circular dichroism when the experiment itself becomes chiral. Although these surfaces are known to yield differences in reflected and transmitted circularly polarized light, the exact mechanism of the interaction has never been directly demonstrated. Here we present a comprehensive linear and nonlinear optical investigation of a metasurface composed of tilted gold nanowires. In the linear regime, we directly demonstrate the selective absorption of circularly polarised light depending on the orientation of the metasurface. In the nonlinear regime, we demonstrate for the first time how second harmonic generation circular dichroism in such extrinsic/pseudo-chiral materials can be understood in terms of effective nonlinear susceptibility tensor elements that switch sign depending on the orientation of the metasurface. By providing fundamental understanding of the chiroptical interactions in achiral metasurfaces, our work opens up new perspectives for the optimisation of their properties. PMID:27553888

  17. Chiral light intrinsically couples to extrinsic/pseudo-chiral metasurfaces made of tilted gold nanowires

    PubMed Central

    Belardini, Alessandro; Centini, Marco; Leahu, Grigore; Hooper, David C.; Li Voti, Roberto; Fazio, Eugenio; Haus, Joseph W.; Sarangan, Andrew; Valev, Ventsislav K.; Sibilia, Concita

    2016-01-01

    Extrinsic or pseudo-chiral (meta)surfaces have an achiral structure, yet they can give rise to circular dichroism when the experiment itself becomes chiral. Although these surfaces are known to yield differences in reflected and transmitted circularly polarized light, the exact mechanism of the interaction has never been directly demonstrated. Here we present a comprehensive linear and nonlinear optical investigation of a metasurface composed of tilted gold nanowires. In the linear regime, we directly demonstrate the selective absorption of circularly polarised light depending on the orientation of the metasurface. In the nonlinear regime, we demonstrate for the first time how second harmonic generation circular dichroism in such extrinsic/pseudo-chiral materials can be understood in terms of effective nonlinear susceptibility tensor elements that switch sign depending on the orientation of the metasurface. By providing fundamental understanding of the chiroptical interactions in achiral metasurfaces, our work opens up new perspectives for the optimisation of their properties. PMID:27553888

  18. A density functional theory of chiral block copolymer melts.

    PubMed

    Wang, Shih-Hao; Kawakatsu, Toshihiro; Chen, Peilong; Lu, Chun-Yi David

    2013-05-21

    A density functional theory is developed for the diblock copolymer melt, where one block contains the segment orientation dependent chiral interaction. In addition to the standard (scalar) pair interaction between the two types of monomers, the chiral block has the additional pairwise interaction, which is linear in the tangent vectors of the segments. We construct a density functional, which contains both the scalar density field and the vector chain alignment field. The quadratic part of the density functional comes from the mean field theory of the microscopic model, whereas the fourth order terms are introduced phenomenologically in the spatially local form. From the stability analysis of this model, we find that the additional chiral interaction shifts the order-disorder transition, which is consistent with the behavior of experimental system. Further numerical calculation reveals a new metastable chiral helical cylinder structure, which is similar to the one found experimentally. Another similar metastable structure but with zigzag modulation is also observed. As the helical and zigzag structures disappear when the chiral interaction is switched off, we understand that the chiral effect is the driving force for the formation of these exotic metastable structures.

  19. Two-pion exchange NN potential from Lorentz-invariant $\\chi$EFT

    SciTech Connect

    Higa, Renato; Robilotta, Manoel; da Rocha, Carlos A

    2006-10-12

    We outline the progress made in the past five years by the Sao Paulo group in the development of a two-pion exchange nucleon-nucleon potential within a Lorentz-invariant framework of (baryon) chiral perturbation theory.

  20. Coherent neutrinoproduction of photons and pions in a chiral effective field theory for nuclei

    NASA Astrophysics Data System (ADS)

    Zhang, Xilin; Serot, Brian D.

    2012-09-01

    Background: The neutrinoproduction of photons and pions from nucleons and nuclei is relevant to the background analysis in neutrino-oscillation experiments [for example, the MiniBooNE; MiniBooNE Collaboration, A. A. Aquilar-Arevalo , Phys. Rev. Lett.0031-900710.1103/PhysRevLett.100.032301 100, 032301 (2008)]. The production from nucleons and incoherent production with Eν⩽0.5GeV have been studied in B. D. Serot and X. Zhang, Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.86.015501 86, 015501 (2012); and X. Zhang and B. D. Serot, Phys. Rev. C1110-865710.1103/PhysRevC.86.035502 86, 035502 (2012).Purpose: Study coherent productions with Eν⩽0.5GeV. Also address the contributions of two contact terms in neutral current (NC) photon production that are partially related to the proposed anomalous ω(ρ), Z boson, and photon interactions.Methods: We work in the framework of a Lorentz-covariant effective field theory (EFT), which contains nucleons, pions, the Δ (1232) (Δs), isoscalar scalar (σ) and vector (ω) fields, and isovector vector (ρ) fields, and incorporates a nonlinear realization of (approximate) SU(2)L⊗SU(2)R chiral symmetry. A revised version of the so-called “optimal approximation” is applied, where one-nucleon interaction amplitude is factorized out and the medium-modifications and pion wave function distortion are included. The calculation is tested against the coherent pion photoproduction data.Results: The computation shows an agreement with the pion photoproduction data, although precisely determining the Δ modification is entangled with one mentioned contact term. The uncertainty in the Δ modification leads to uncertainties in both pion and photon neutrinoproductions. In addition, the contact term plays a significant role in NC photon production.Conclusions: First, the contact term increases NC photon production by ˜10% assuming a reasonable range of the contact coupling, which however seems not significant enough to explain the Mini

  1. Chiral anomalies and differential geometry

    SciTech Connect

    Zumino, B.

    1983-10-01

    Some properties of chiral anomalies are described from a geometric point of view. Topics include chiral anomalies and differential forms, transformation properties of the anomalies, identification and use of the anomalies, and normalization of the anomalies. 22 references. (WHK)

  2. Active Chiral Plasmonics.

    PubMed

    Yin, Xinghui; Schäferling, Martin; Michel, Ann-Katrin U; Tittl, Andreas; Wuttig, Matthias; Taubner, Thomas; Giessen, Harald

    2015-07-01

    Active control over the handedness of a chiral metamaterial has the potential to serve as key element for highly integrated polarization engineering approaches, polarization sensitive imaging devices, and stereo display technologies. However, this is hard to achieve as it seemingly involves the reconfiguration of the metamolecule from a left-handed into a right-handed enantiomer and vice versa. This type of mechanical actuation is intricate and usually neither monolithically realizable nor viable for high-speed applications. Here, enabled by the phase change material Ge3Sb2Te6 (GST-326), we demonstrate a tunable and switchable mid-infrared plasmonic chiral metamaterial in a proof-of-concept experiment. A large tunability range of the circular dichroism response from λ = 4.15 to 4.90 μm is achieved, and we experimentally demonstrate that the combination of a passive bias-type chiral layer with the active chiral metamaterial allows for switchable chirality, that is, the reversal of the circular dichroism sign, in a fully planar, layered design without the need for geometrical reconfiguration. Because phase change materials can be electrically and optically switched, our designs may open up a path for highly integrated mid-IR polarization engineering devices that can be modulated on ultrafast time scales.

  3. Chirality dependent elastic properties of single-walled boron nitride nanotubes under uniaxial and torsional loading

    SciTech Connect

    Anoop Krishnan, N. M. Ghosh, Debraj

    2014-02-14

    The elastic behavior of single-walled boron nitride nanotubes is studied under axial and torsional loading. Molecular dynamics simulation is carried out with a tersoff potential for modeling the interatomic interactions. Different chiral configurations with similar diameter are considered to study the effect of chirality on the elastic and shear moduli. Furthermore, the effects of tube length on elastic modulus are also studied by considering different aspects ratios. It is observed that both elastic and shear moduli depend upon the chirality of a nanotube. For aspect ratios less than 15, the elastic modulus reduces monotonically with an increase in the chiral angle. For chiral nanotubes, the torsional response shows a dependence on the direction of loading. The difference between the shear moduli against and along the chiral twist directions is maximum for chiral angle of 15°, and zero for zigzag (0°) and armchair (30°) configurations.

  4. Chirality transfer from gold nanocluster to adsorbate evidenced by vibrational circular dichroism

    PubMed Central

    Dolamic, Igor; Varnholt, Birte; Bürgi, Thomas

    2015-01-01

    The transfer of chirality from one set of molecules to another is fundamental for applications in chiral technology and has likely played a crucial role for establishing homochirality on earth. Here we show that an intrinsically chiral gold cluster can transfer its handedness to an achiral molecule adsorbed on its surface. Solutions of chiral Au38(2-PET)24 (2-PET=2-phenylethylthiolate) cluster enantiomers show strong vibrational circular dichroism (VCD) signals in vibrations of the achiral adsorbate. Density functional theory (DFT) calculations reveal that 2-PET molecules adopt a chiral conformation. Chirality transfer from the cluster to the achiral adsorbate is responsible for the preference of one of the two mirror images. Intermolecular interactions between the adsorbed molecules on the crowded cluster surface seem to play a dominant role for the phenomena. Such chirality transfer from metals to adsorbates likely plays an important role in heterogeneous enantioselective catalysis. PMID:25960309

  5. Chiral recognition and selection during the self-assembly process of protein-mimic macroanions

    SciTech Connect

    Yin, Panchao; Zhang, Zhi-Ming; Lv, Hongjin; Li, Tao; Haso, Fadi; Hu, Lang; Zhang, Baofang; Basca, John; Wei, Yongge; Gao, Yanqing; Hou, Yu; Li, Yang-Guang; Hill, Craig L.; Wang, En-Bo; Liu, Tianbo

    2015-03-01

    The research on chiral recognition and chiral selection is not only fundamental in resolving the puzzle of homochirality, but also instructive in chiral separation and stereoselective catalysis. Here we report the chiral recognition and chiral selection during the self-assembly process of two enantiomeric wheel-shaped macroanions, [Fe28(μ3-O)8(Tart)16(HCOO)24]20- (Tart=D- or L-tartaric acid tetra-anion). The enantiomers are observed to remain self-sorted and self-assemble into their individual assemblies in their racemic mixture solution. The addition of chiral co-anions can selectively suppress the self-assembly process of the enantiomeric macroanions, which is further used to separate the two enantiomers from their mixtures on the basis of the size difference between the monomers and the assemblies. We believe that delicate long-range electrostatic interactions could be responsible for such high-level chiral recognition and selection.

  6. Chiral recognition and selection during the self-assembly process of protein-mimic macroanions.

    PubMed

    Yin, Panchao; Zhang, Zhi-Ming; Lv, Hongjin; Li, Tao; Haso, Fadi; Hu, Lang; Zhang, Baofang; Bacsa, John; Wei, Yongge; Gao, Yanqing; Hou, Yu; Li, Yang-Guang; Hill, Craig L; Wang, En-Bo; Liu, Tianbo

    2015-01-01

    The research on chiral recognition and chiral selection is not only fundamental in resolving the puzzle of homochirality, but also instructive in chiral separation and stereoselective catalysis. Here we report the chiral recognition and chiral selection during the self-assembly process of two enantiomeric wheel-shaped macroanions, [Fe28(μ3-O)8(Tart)16(HCOO)24](20-) (Tart=D- or L-tartaric acid tetra-anion). The enantiomers are observed to remain self-sorted and self-assemble into their individual assemblies in their racemic mixture solution. The addition of chiral co-anions can selectively suppress the self-assembly process of the enantiomeric macroanions, which is further used to separate the two enantiomers from their mixtures on the basis of the size difference between the monomers and the assemblies. We believe that delicate long-range electrostatic interactions could be responsible for such high-level chiral recognition and selection. PMID:25756393

  7. Chiral recognition and selection during the self-assembly process of protein-mimic macroanions.

    PubMed

    Yin, Panchao; Zhang, Zhi-Ming; Lv, Hongjin; Li, Tao; Haso, Fadi; Hu, Lang; Zhang, Baofang; Bacsa, John; Wei, Yongge; Gao, Yanqing; Hou, Yu; Li, Yang-Guang; Hill, Craig L; Wang, En-Bo; Liu, Tianbo

    2015-03-10

    The research on chiral recognition and chiral selection is not only fundamental in resolving the puzzle of homochirality, but also instructive in chiral separation and stereoselective catalysis. Here we report the chiral recognition and chiral selection during the self-assembly process of two enantiomeric wheel-shaped macroanions, [Fe28(μ3-O)8(Tart)16(HCOO)24](20-) (Tart=D- or L-tartaric acid tetra-anion). The enantiomers are observed to remain self-sorted and self-assemble into their individual assemblies in their racemic mixture solution. The addition of chiral co-anions can selectively suppress the self-assembly process of the enantiomeric macroanions, which is further used to separate the two enantiomers from their mixtures on the basis of the size difference between the monomers and the assemblies. We believe that delicate long-range electrostatic interactions could be responsible for such high-level chiral recognition and selection.

  8. Chirality-induced spin current through spiral magnets

    NASA Astrophysics Data System (ADS)

    Watanabe, Hiroki; Hoshi, Koujiro; Ohe, Jun-ichiro

    2016-09-01

    Spin-polarized current through helimagnets and the conductance modulation due to the chirality mismatch are studied numerically. The one-dimensional spiral magnet structure is obtained by taking into account the Dzyaloshinskii-Moriya interaction and the ferromagnetic interaction. Although the spiral magnetic structure consists of the y -z components of the magnetization, the conduction electron through the spiral magnet is polarized in the x direction, and its sign depends on the chirality of the spiral structure. We also investigate charge transport through the junction system consisting of two helimagnets. Similar to the giant magnetoresistance in the uniform ferromagnet, the conductance is reduced significantly by attaching the helimagnets with different chiralities. It is possible that our proposed mechanism can make use of the chirality measuring method by using electron transport and an alternative type of magnetoresistance using a topological property.

  9. Chirality and Life

    NASA Astrophysics Data System (ADS)

    Barron, Laurence D.

    Chirality, meaning handedness, pervades much of modern science, from the physics of elementary particles to the chemistry of life. The amino acids and sugars from which the central molecules of life—proteins and nucleic acids—are constructed exhibit homochirality, which is expected to be a key biosignature in astrobiology. This article provides a brief review of molecular chirality and its significance for the detection of extant or extinct life on other worlds. Fundamental symmetry aspects are emphasized since these bring intrinsic physical properties of the universe to bear on the problem of the origin and role of homochirality in the living world.

  10. Chirality and Life

    NASA Astrophysics Data System (ADS)

    Barron, Laurence D.

    2008-03-01

    Chirality, meaning handedness, pervades much of modern science, from the physics of elementary particles to the chemistry of life. The amino acids and sugars from which the central molecules of life—proteins and nucleic acids—are constructed exhibit homochirality, which is expected to be a key biosignature in astrobiology. This article provides a brief review of molecular chirality and its significance for the detection of extant or extinct life on other worlds. Fundamental symmetry aspects are emphasized since these bring intrinsic physical properties of the universe to bear on the problem of the origin and role of homochirality in the living world.

  11. An investigation of ab initio shell-model interactions derived by no-core shell model

    NASA Astrophysics Data System (ADS)

    Wang, XiaoBao; Dong, GuoXiang; Li, QingFeng; Shen, CaiWan; Yu, ShaoYing

    2016-09-01

    The microscopic shell-model effective interactions are mainly based on the many-body perturbation theory (MBPT), the first work of which can be traced to Brown and Kuo's first attempt in 1966, derived from the Hamada-Johnston nucleon-nucleon potential. However, the convergence of the MBPT is still unclear. On the other hand, ab initio theories, such as Green's function Monte Carlo (GFMC), no-core shell model (NCSM), and coupled-cluster theory with single and double excitations (CCSD), have made many progress in recent years. However, due to the increasing demanding of computing resources, these ab initio applications are usually limited to nuclei with mass up to A = 16. Recently, people have realized the ab initio construction of valence-space effective interactions, which is obtained through a second-time renormalization, or to be more exactly, projecting the full-manybody Hamiltonian into core, one-body, and two-body cluster parts. In this paper, we present the investigation of such ab initio shell-model interactions, by the recent derived sd-shell effective interactions based on effective J-matrix Inverse Scattering Potential (JISP) and chiral effective-field theory (EFT) through NCSM. In this work, we have seen the similarity between the ab initio shellmodel interactions and the interactions obtained by MBPT or by empirical fitting. Without the inclusion of three-body (3-bd) force, the ab initio shell-model interactions still share similar defects with the microscopic interactions by MBPT, i.e., T = 1 channel is more attractive while T = 0 channel is more repulsive than empirical interactions. The progress to include more many-body correlations and 3-bd force is still badly needed, to see whether such efforts of ab initio shell-model interactions can reach similar precision as the interactions fitted to experimental data.

  12. Chirality, quantum mechanics, and biological determinism

    NASA Astrophysics Data System (ADS)

    Davies, P. C. W.

    2006-08-01

    The holy grail of astrobiology is the discovery of a second sample of life that has emerged de novo, independently of life on Earth (as opposed to extraterrestrial life that shares a common origin with terrestrial life via a panspermia process). It would then be possible to separate aspects of biology that are lawlike and expected from those that are accidental and contingent, and thus to address the question of whether the laws of nature are intrinsically bio-friendly. The popular assumption that life is an almost inevitable product of physics and chemistry, and therefore widespread in the universe, is known as biological determinism. It remains an open question whether biological determinism is correct, as there is little direct evidence in its favour from fundamental physics. Homochirality is a deep property of known life, and provides an important test case for the competing ideas of contingency versus lawfulness - or chance versus necessity. Conceivably, a chiral signature is imprinted on life by fundamental physics via parity-violating mixing of the weak and electromagnetic interactions. If so, homochirality would be universal and lawlike. On the other hand, it may be the result of chance: a random molecular accident during the pre-biotic phase. If the latter explanation is correct, one could expect that a second sample of life may have opposite chiral signature even if it resembled known life in its basic biochemistry. There is thus a curious obverse relationship between chirality and biogenesis in relation to biological determinism. If the chiral signature of life is the product of chance, we may hope to discover "mirror life" (i.e. organisms with opposite chiral signature) as evidence of a second genesis, and the latter would establish that life's emergence from non-life is quasi-deterministic. On the other hand, if the chiral signature is determined by fundamental physics, then it may be much harder to establish an independent origin for extraterrestrial

  13. Strong WW scattering chiral lagrangians, unitarity and resonances

    SciTech Connect

    Pelaez, J.R.

    1996-08-01

    Chiral lagrangians provide a model independent description of the strongly interacting symmetry breaking sector. In this work, first we review the LHC sensitivity to the chiral parameters (in the hardest case of non-resonant low-energy WW scattering). Later we show how to reproduce or predict the resonance spectrum by means of dispersion theory and the inverse amplitude method. We present a parameter space scan that covers many different strong WW scattering scenarios.

  14. Chiral assembly of weakly curled hard rods: Effect of steric chirality and polarity

    SciTech Connect

    Wensink, H. H. Morales-Anda, L.

    2015-10-14

    We theoretically investigate the pitch of lyotropic cholesteric phases composed of slender rods with steric chirality transmitted via a weak helical deformation of the backbone. In this limit, the model is amenable to analytical treatment within Onsager theory and a closed expression for the pitch versus concentration and helical shape can be derived. Within the same framework, we also briefly review the possibility of alternative types of chiral order, such as twist-bend or screw-like nematic phases, finding that cholesteric order dominates for weakly helical distortions. While long-ranged or “soft” chiral forces usually lead to a pitch decreasing linearly with concentration, steric chirality leads to a much steeper decrease of quadratic nature. This reveals a subtle link between the range of chiral intermolecular interaction and the pitch sensitivity with concentration. A much richer dependence on the thermodynamic state is revealed for polar helices where parallel and anti-parallel pair alignments along the local director are no longer equivalent. It is found that weak temperature variations may lead to dramatic changes in the pitch, despite the lyotropic nature of the assembly.

  15. Administrative simplification: adoption of operating rules for health care electronic funds transfers (EFT) and remittance advice transactions. Interim final rule with comment period.

    PubMed

    2012-08-10

    This interim final rule with comment period implements parts of section 1104 of the Affordable Care Act which requires the adoption of operating rules for the health care electronic funds transfers (EFT) and remittance advice transaction. PMID:22888504

  16. Inversion of Supramolecular Chirality by Sonication-Induced Organogelation

    PubMed Central

    Maity, Sibaprasad; Das, Priyadip; Reches, Meital

    2015-01-01

    Natural helical structures have inspired the formation of well-ordered peptide-based chiral nanostructures in vitro. These structures have drawn much attention owing to their diverse applications in the area of asymmetric catalysts, chiral photonic materials, and nanoplasmonics. The self-assembly of two enantiomeric fluorinated aromatic dipeptides into ordered chiral fibrillar nanostructures upon sonication is described. These fibrils form organogels. Our results clearly indicate that fluorine-fluorine interactions play an important role in self-assembly. Circular dichroism analysis revealed that both peptides (peptides 1 and 2), containing two fluorines, depicted opposite cotton effects in their monomeric form compared with their aggregated form. This shows that supramolecular chirality inversion took place during the stimuli-responsive self-aggregation process. Conversely, peptide 3, containing one fluorine, did not exhibit chirality inversion in sonication-induced organogelation. Therefore, our results clearly indicate that fluorination plays an important role in the organogelation process of these aromatic dipeptides. Our findings may have broad implications regarding the design of chiral nanostructures for possible applications such as chiroptical switches, asymmetric catalysis, and chiral recognitions. PMID:26553508

  17. Inversion of Supramolecular Chirality by Sonication-Induced Organogelation

    NASA Astrophysics Data System (ADS)

    Maity, Sibaprasad; Das, Priyadip; Reches, Meital

    2015-11-01

    Natural helical structures have inspired the formation of well-ordered peptide-based chiral nanostructures in vitro. These structures have drawn much attention owing to their diverse applications in the area of asymmetric catalysts, chiral photonic materials, and nanoplasmonics. The self-assembly of two enantiomeric fluorinated aromatic dipeptides into ordered chiral fibrillar nanostructures upon sonication is described. These fibrils form organogels. Our results clearly indicate that fluorine-fluorine interactions play an important role in self-assembly. Circular dichroism analysis revealed that both peptides (peptides 1 and 2), containing two fluorines, depicted opposite cotton effects in their monomeric form compared with their aggregated form. This shows that supramolecular chirality inversion took place during the stimuli-responsive self-aggregation process. Conversely, peptide 3, containing one fluorine, did not exhibit chirality inversion in sonication-induced organogelation. Therefore, our results clearly indicate that fluorination plays an important role in the organogelation process of these aromatic dipeptides. Our findings may have broad implications regarding the design of chiral nanostructures for possible applications such as chiroptical switches, asymmetric catalysis, and chiral recognitions.

  18. Chiral separation and twin-beam photonics

    NASA Astrophysics Data System (ADS)

    Bradshaw, David S.; Andrews, David L.

    2016-03-01

    It is well-known that, in a homogeneous fluid medium, most optical means that afford discrimination between molecules of opposite handedness are intrinsically weak effects. The reason is simple: the wide variety of origins for differential response commonly feature real or virtual electronic transitions that break a parity condition. Despite being electric dipole allowed, they manifest the chirality of the material in which they occur by breaking a selection rule that would otherwise preclude the simultaneous involvement of magnetic dipole or electric quadrupole forms of coupling. Although the latter are typically weaker than electric dipole effects by several orders of magnitude, it is the involvement of these weak forms of interaction that are responsible for chiral sensitivity. There have been a number of attempts to cleverly exploit novel optical configurations to enhance the relative magnitude - and hence potentially the efficiency - of chiral discrimination. The prospect of success in any such venture is enticing, because of the huge impact that such an advance might be expected to have in the health, food and medical sectors. Some of these proposals have utilized mirror reflection, and others surface plasmon coupling, or optical binding methods. Several recent works in the literature have drawn attention to a further possibility: the deployment of optical beam interference as a means to achieve chiral separations of sizeable extent. In this paper the underlying theory is fully developed to identify the true scope and limitations of such an approach.

  19. Chiral damping in magnetic domain walls dynamics

    NASA Astrophysics Data System (ADS)

    Jué, Emilie

    Domain wall (DW) motion in materials with structural inversion asymmetry (SIA) and high spin-orbit coupling has attracted much interest in the recent years due to the discovery of unexpected physical mechanisms. Especially, it has been shown that the DW dynamics in such materials can be explained by chiral DWs with (partly or fully) Néel structure, whose stability derives from an interfacial Dzyaloshinskii-Moriya interaction (DMI). In this work, we show that DMI is not the only effect inducing chiral dynamics and demonstrate the existence of a chiral damping. This result is supported by the study of the asymmetry induced by an in-plane magnetic field on field induced domain wall motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. Using time reversal properties, we show that this asymmetry cannot be attributed to an effective field but originates from a purely dissipative mechanism. The observation of chiral damping, not only enriches the spectrum of physical phenomena engendered by the SIA, but since it can coexist with DMI it is essential for conceiving DW and skyrmion devices

  20. Chiral damping of magnetic domain walls

    NASA Astrophysics Data System (ADS)

    Jué, Emilie; Safeer, C. K.; Drouard, Marc; Lopez, Alexandre; Balint, Paul; Buda-Prejbeanu, Liliana; Boulle, Olivier; Auffret, Stephane; Schuhl, Alain; Manchon, Aurelien; Miron, Ioan Mihai; Gaudin, Gilles

    2016-03-01

    Structural symmetry breaking in magnetic materials is responsible for the existence of multiferroics, current-induced spin-orbit torques and some topological magnetic structures. In this Letter we report that the structural inversion asymmetry (SIA) gives rise to a chiral damping mechanism, which is evidenced by measuring the field-driven domain-wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The DW dynamics associated with the chiral damping and those with Dzyaloshinskii-Moriya interaction (DMI) exhibit identical spatial symmetry. However, both scenarios are differentiated by their time reversal properties: whereas DMI is a conservative effect that can be modelled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing one to distinguish the physical mechanism. The chiral damping enriches the spectrum of physical phenomena engendered by the SIA, and is essential for conceiving DW and skyrmion devices owing to its coexistence with DMI (ref. ).

  1. Monopoles and fractional vortices in chiral superconductors

    PubMed Central

    Volovik, G. E.

    2000-01-01

    I discuss two exotic objects that must be experimentally identified in chiral superfluids and superconductors. These are (i) the vortex with a fractional quantum number (N = 1/2 in chiral superfluids, and N = 1/2 and N = 1/4 in chiral superconductors), which plays the part of the Alice string in relativistic theories and (ii) the hedgehog in the ^l field, which is the counterpart of the Dirac magnetic monopole. These objects of different dimensions are topologically connected. They form the combined object that is called a nexus in relativistic theories. In chiral superconductors, the nexus has magnetic charge emanating radially from the hedgehog, whereas the half-quantum vortices play the part of the Dirac string. Each half-quantum vortex supplies the fractional magnetic flux to the hedgehog, representing 1/4 of the “conventional” Dirac string. I discuss the topological interaction of the superconductor's nexus with the ‘t Hooft–Polyakov magnetic monopole, which can exist in Grand Unified Theories. The monopole and the hedgehog with the same magnetic charge are topologically confined by a piece of the Abrikosov vortex. Such confinement makes the nexus a natural trap for the magnetic monopole. Other properties of half-quantum vortices and monopoles are discussed as well, including fermion zero modes. PMID:10716980

  2. Interparticle Chiral Recognition of Enantiomers: A Nanoparticle-Based Regulation Strategy

    SciTech Connect

    Lim, I-Im S.; Mott, Derrick; Engelhard, Mark H.; Pan, Yi; Kamodia, Shalini; Luo, Jin; Njoki, Peter; Zhou, Shuiqin; Wang, Lichang; Zhong, Chuan-Jian

    2009-01-15

    The ability to regulate how molecular chirality of enantiomeric amino acids operates in biological systems constitutes the basis of drug design for specific targeting of diseases. We report herein nanoparticle-administered chiral recognition of enantiomeric cysteines as a general molecular tuning strategy to regulate the interactions of chiral amino acids. This strategy exploits the pairwise zwitterion interaction of enantiomeric cysteines adsorbed on gold nanoparticles to create a chiral footprint for interparticle enantiomeric recognition. The chiral recognition is evidenced by the sharp kinetic contrast between interparticle homochiral and heterochiral reactivities. The experimental-theoretical correlation of the interparticle reactivity with the enantiomeric ratio reveals that the chiral recognition is tunable both molecularly and by nanoparticles, which has potential applications in drug design for targeting or delivery.

  3. Role of surface interactions in the dynamics of chiral isopentylcyanobiphenyl mixed with Al2O3 powder as studied by dielectric spectroscopy: numerical analysis.

    PubMed

    Bąk, A; Chłędowska, K

    2011-06-01

    The results of dielectric measurements for a mixture of chiral liquid crystal 5*CB with Al(2)O(3) powder are given. A detailed analysis of the dielectric spectra enabled us to obtain information about the influence of the Al(2)O(3) grains on the dynamics of the liquid-crystal molecules. Numerical analysis of the results confirmed that the dielectric spectra obtained are complex. In the low-frequency range they are dominated by ionic conductivity while in the whole frequency range two maxima appear. One of them is related to rotations of the molecules around their short axes. In the isotropic phase the corresponding values of the relaxation times are very close to those for bulk 5*CB. Relaxation and conduction processes can be described by a Vogel-Fulcher-Tammann function. In the cholesteric phase, rotation of 5*CB molecules trapped in the pores of Al(2)O(3) occurs. Another relaxation process results from dynamics of 5*CB molecules anchoring to Al(2)O(3) grains. The temperature dependence of relaxation times related to this process is nonmonotonic.

  4. Quark matter in a parallel electric and magnetic field background: Chiral phase transition and equilibration of chiral density

    NASA Astrophysics Data System (ADS)

    Ruggieri, M.; Peng, G. X.

    2016-05-01

    In this article, we study spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field E and magnetic field B . We use a Nambu-Jona-Lasinio model with a local kernel interaction to compute the relevant quantities to describe chiral symmetry breaking at a finite temperature for a wide range of E and B . We study the effect of this background on the inverse catalysis of chiral symmetry breaking for E and B of the same order of magnitude. We then focus on the effect of the equilibration of chiral density n5 , produced dynamically by an axial anomaly on the critical temperature. The equilibration of n5 , a consequence of chirality-flipping processes in the thermal bath, allows for the introduction of the chiral chemical potential μ5, which is computed self-consistently as a function of the temperature and field strength by coupling the number equation to the gap equation and solving the two within an expansion in E /T2 , B /T2 , and μ52/T2 . We find that even if chirality is produced and equilibrates within a relaxation time τM , it does not change drastically the thermodynamics, with particular reference to the inverse catalysis induced by the external fields, as long as the average μ5 at equilibrium is not too large.

  5. Optical chirality sensing using macrocycles, synthetic and supramolecular oligomers/polymers, and nanoparticle based sensors.

    PubMed

    Chen, Zhan; Wang, Qian; Wu, Xin; Li, Zhao; Jiang, Yun-Bao

    2015-07-01

    Optical sensors that respond to enantiomeric excess of chiral analytes are highly demanded in chirality related research fields and demonstrate their potential in many applications, for example, screening of asymmetric reaction products. Most sensors developed so far are small molecules. This Tutorial Review covers recent advances in chirality sensing systems that are different from the traditional small molecule-based sensors, by using macrocycles, synthetic oligomers/polymers, supramolecular polymers and nanoparticles as the sensors, in which supramolecular interactions operate. PMID:25714523

  6. Condensations of single DNA molecules induced by heptaplatin and its chiral isomer

    SciTech Connect

    Zhang, Hong-Yan; Liu, Yu-Ru; Li, Wei; Li, Hui; Dou, Shuo-Xing; Xie, Ping; Wang, Wei-Chi; Wang, Peng-Ye

    2014-08-15

    Heptaplatin is a third-generation platinum antitumor drug. It has a chiral isomer. We studied the interactions between the two isomers and DNA by using magnetic tweezers and atomic force microscopy (AFM) to investigate the effect of chiralities of the isomers on the interactions. We found that the extension curves and average condensation rates of DNA molecules incubated with heptaplatin were nearly the same as those incubated with its chiral isomer. In addition, the structures of DNA molecules incubated with heptaplatin were also similar to those incubated with its chiral isomer. These results indicate the difference in chirality of the two isomers does not induce different interactions of the isomers with DNA. Our study may facilitate the understanding of interactions of platinum complexes with DNA and the design of new antitumor platinum complexes.

  7. Novel chiral recognition elements for molecularly imprinted polymer preparation.

    PubMed

    Knutsson, M; Andersson, H S; Nicholls, I A

    1998-01-01

    The use of a novel chiral functional monomer system in molecular imprinting protocols is described. The monomer, dibenzyl (2R,3R)-O-monoacryloyl tartrate, possesses a hydroxyl moiety which can be used to direct template-functional monomer interactions during molecular imprinting polymerization. This system simultaneously positions benzyl ester-protected carboxyl groups in close proximity to the template, which upon deprotection yield recognition sites with stronger ligand-binding capacities. Furthermore, the inherent chirality of the monomer engenders the polymer with an inbuilt preference for a given stereoisomer. Application of the system to the molecular imprinting of the cinchonidine alkaloids (+)-cinchonine and (-)-cinchonidine yielded stereoselective polymers. The effect of imprinting (+)-cinchonine produced a polymer which more than reversed the inherent chiral selectivity of the chiral monomer residues present in the matrix.

  8. Molecular modeling study of chiral drug crystals: lattice energy calculations.

    PubMed

    Li, Z J; Ojala, W H; Grant, D J

    2001-10-01

    The lattice energies of a number of chiral drugs with known crystal structures were calculated using Dreiding II force field. The lattice energies, including van der Waals, Coulombic, and hydrogen-bonding energies, of homochiral and racemic crystals of some ephedrine derivatives and of several other chiral drugs, are compared. The calculated energies are correlated with experimental data to probe the underlying intermolecular forces responsible for the formation of racemic species, racemic conglomerates, or racemic compounds, termed chiral discrimination. Comparison of the calculated energies among ephedrine derivatives reveals that a greater Coulombic energy corresponds to a higher melting temperature, while a greater van der Waals energy corresponds to a larger enthalpy of fusion. For seven pairs of homochiral and racemic compounds, correlation of the differences between the two forms in the calculated energies and experimental enthalpy of fusion suggests that the van der Waals interactions play a key role in the chiral discrimination in the crystalline state. For salts of the chiral drugs, the counter ions diminish chiral discrimination by increasing the Coulombic interactions. This result may explain why salt forms favor the formation of racemic conglomerates, thereby facilitating the resolution of racemates.

  9. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    NASA Astrophysics Data System (ADS)

    de Jesús Pelayo, José; Valencia, Israel; Díaz, Gabriela; López-Lozano, Xóchitl; Garzón, Ignacio L.

    2015-12-01

    The interaction of biological molecules like chiral amino acids with chiral metal clusters is becoming an interesting and active field of research because of its potential impact in, for example, chiral molecular recognition phenomena. In particular, the enantiospecific adsorption (EA) of cysteine (Cys) on a chiral Au55 cluster was theoretically predicted a few years ago. In this work, we present theoretical results, based on density functional theory, of the EA of non-zwitterionic cysteine interacting with the C3-Au34 chiral cluster, which has been experimentally detected in gas phase, using trapped ion electron diffraction. Our results show that, indeed, the adsorption energy of the amino acid depends on which enantiomers participate in the formation Cys-Au34 chiral complex. EA was obtained in the adsorption modes where both the thiol, and the thiol-amino functional groups of Cys are adsorbed on low-coordinated sites of the metal cluster surface. Similarly to what was obtained for the Cys-Au55 chiral complex, in the present work, it is found that the EA is originated from the different strength and location of the bond between the COOH functional group and surface Au atoms of the Au34 chiral cluster. Calculations of the vibrational spectrum for the different Cys-Au34 diastereomeric complexes predict the existence of a vibro-enantiospecific effect, indicating that the vibrational frequencies of the adsorbed amino acid depend on its handedness. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by G. Delgado Barrio, A. Solov'Yov, P. Villarreal, R. Prosmiti.

  10. Chiral discrimination in the confined environment of biological nanospace

    NASA Astrophysics Data System (ADS)

    Nandi, Nilashis

    Although chiral discrimination in biological systems is overwhelmingly present, its molecular mechanism remained a puzzle. Why the basic blocks of life like L-amino acid and D-sugar are not being scrambled and retain enantiomeric purity since evolution is an unresolved question. In the present review we focus on the recent experimental and computational studies on the chiral discrimination in reactions such as peptide synthesis and aminoacylation. Experimental studies have shown that a clear homochiral preference exists favouring L-amino acid. Recent combined quantum mechanical/molecular mechanical studies explain the high level of stereospecificity of the processes and revealed multiple factors responsible for the discrimination and concomitant retention of the biological homochirality. Chirality of the relevant molecular segments and the intricate interaction between them as well as with the surrounding residues are important. The confinement of the chiral reactants within the biological nanospaces like the peptidyl transferase centre in tRNA and active site of the aminoacyl transferase as well as the nanoscale proximity are important for the manifestation of the discrimination. Multiple favourable influences of the stereochemistry of the natural chirality (D-form) of the sugar ring are noted. This explains the heterochiral relationship of the D-sugar and L-amino acid in biology. In addition to factors such as chirality, confinement and nanoscale proximity of the molecular segments, the network of electrostatic interaction present in the active site plays a significant role in the chiral discrimination in aminoacylation. Chiral discriminations in the biological cavities of nucleic acid and cyclodextrin are also briefly reviewed.

  11. Optical properties of chiral nanotubes

    NASA Astrophysics Data System (ADS)

    Cecilia, Noguez; Román-Velázquez Carlos, E.; Ariadna, Sánchez; Montes Lilia, Meza

    2004-03-01

    A recent theoretical model [1] is applied to study the optical properties chiral nanostructures like carbon nanotubes. We calculate the Circular Dichroism (CD) spectra for carbon nanotubes with different chirality. The calculated CD spectra show features that allow us to distinguish between nanotubes with different indexes of chirality. Other nanostructures, like chiral fullerenes are also investigated.These results provide theoretical support for the quantification of chirality and its measurement, using the CD lineshapes of chiral. This work has been partly financed by CONACyT grant No. 36651-E and by DGAPA-UNAM grants No. IN104201. [1] C. E. Roman-Velazquez, et al., J. of Phys. Chem. B (Letter) 107, 12035 (2003)

  12. Tailoring the chirality of light emission with spherical Si-based antennas.

    PubMed

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-21

    Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission.

  13. Tailoring the chirality of light emission with spherical Si-based antennas.

    PubMed

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-21

    Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission. PMID:27141982

  14. Chiral symmetry and pentaquarks

    SciTech Connect

    Dmitri Diakonov

    2004-07-01

    Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate pentaquark masses by some 500 MeV and why in the fully relativistic approach to baryons pentaquarks turn out to be light. I discuss briefly why it can be easier to produce pentaquarks at low than at high energies.

  15. Chiral Biomarkers in Meteorites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    2010-01-01

    The chirality of organic molecules with the asymmetric location of group radicals was discovered in 1848 by Louis Pasteur during his investigations of the rotation of the plane of polarization of light by crystals of sodium ammonium paratartrate. It is well established that the amino acids in proteins are exclusively Levorotary (L-aminos) and the sugars in DNA and RNA are Dextrorotary (D-sugars). This phenomenon of homochirality of biological polymers is a fundamental property of all life known on Earth. Furthermore, abiotic production mechanisms typically yield recemic mixtures (i.e. equal amounts of the two enantiomers). When amino acids were first detected in carbonaceous meteorites, it was concluded that they were racemates. This conclusion was taken as evidence that they were extraterrestrial and produced by abiologically. Subsequent studies by numerous researchers have revealed that many of the amino acids in carbonaceous meteorites exhibit a significant L-excess. The observed chirality is much greater than that produced by any currently known abiotic processes (e.g. Linearly polarized light from neutron stars; Circularly polarized ultraviolet light from faint stars; optically active quartz powders; inclusion polymerization in clay minerals; Vester-Ulbricht hypothesis of parity violations, etc.). This paper compares the measured chirality detected in the amino acids of carbonaceous meteorites with the effect of these diverse abiotic processes. IT is concluded that the levels observed are inconsistent with post-arrival biological contamination or with any of the currently known abiotic production mechanisms. However, they are consistent with ancient biological processes on the meteorite parent body. This paper will consider these chiral biomarkers in view of the detection of possible microfossils found in the Orgueil and Murchison carbonaceous meteorites. Energy dispersive x-ray spectroscopy (EDS) data obtained on these morphological biomarkers will be

  16. Generalized simplicial chiral models

    NASA Astrophysics Data System (ADS)

    Alimohammadi, Masoud

    2000-02-01

    Using the auxiliary field representation of the simplicial chiral models on a ( d-1)-dimensional simplex, the simplicial chiral models are generalized through replacing the term Tr (AA †) in the Lagrangian of these models by an arbitrary class function of AA †; V(AA †) . This is the same method used in defining the generalized two-dimensional Yang-Mills theories (gYM 2) from ordinary YM 2. We call these models the "generalized simplicial chiral models". Using the results of the one-link integral over a U( N) matrix, the large- N saddle-point equations for eigenvalue density function ρ( z) in the weak ( β> βc) and strong ( β< βc) regions are computed. In d=2, where the model is in some sense related to the gYM 2 theory, the saddle-point equations are solved for ρ( z) in the two regions, and the explicit value of critical point βc is calculated for V(B)= Tr B n(B=AA †) . For V(B)= Tr B 2, Tr B 3, and Tr B4, the critical behaviour of the model at d=2 is studied, and by calculating the internal energy, it is shown that these models have a third order phase transition.

  17. Chiral microemulsion electrokinetic chromatography with two chiral components: Improved separations via synergies between a chiral surfactant and a chiral cosurfactant.

    PubMed

    Kahle, Kimberly A; Foley, Joe P

    2006-02-01

    In this study, the combination of two chiral components in a microemulsion formulation for the separation of enantiomers via microemulsion EKC (MEEKC) was successfully accomplished. Previous publications of chiral microemulsions have utilized only one chiral entity; the surfactant, cosurfactant, or oil was chiral. This is the first study, to date, of the effects of using two chiral species in a single pseudostationary phase (PSP). The chiral surfactant dodecoxycarbonylvaline (DDCV) was used in conjunction with the chiral cosurfactant S-2-hexanol. Ethyl acetate was incorporated as the oil core of the microemulsion and the buffer was 50 mM phosphate at a pH of 7. Additionally, a microemulsion prepared with racemic 2-hexanol was used for comparison to a previous DDCV microemulsion and as a baseline for the newly formulated dual chiral microemulsion. The efficiencies, resolutions, and enantioselectivities for the S-2-hexanol, racemic 2-hexanol, and original 1-butanol DDCV microemulsions are compared. The hexanol-based PSPs provide improved efficiencies and resolutions. To evaluate the combination of each DDCV enantiomer (R and S) with S-2-hexanol, changes in Gibb's free energy were calculated. A synergistic effect was found when two chiral components were combined to form a microemulsion.

  18. Chiral d -Wave Superfluid in Periodically Driven Lattices

    NASA Astrophysics Data System (ADS)

    Zhang, Shao-Liang; Lang, Li-Jun; Zhou, Qi

    2015-11-01

    A chiral d -wave superfluid is a preliminary example of interacting topological matter. However, unlike s -wave superfluids prevalent in nature, its existence requires a strong d -wave interaction, a criterion that is difficult to access in ordinary systems. There is no experimental observation of such unconventional superfluid at the moment. Here, we present a new principle for creating a two-dimensional (2D) chiral d -wave superfluid using periodically driven lattices. Because of an imprinted 2D pseudospin-orbit coupling, where the sublattice index serves as the pseudospin, the s -wave interaction between two hyperfine spin states naturally creates a chiral d -wave superfluid. This scheme can be directly implemented in current experiments.

  19. Phases of N=1 Supersymmetric Chiral Gauge Theories

    SciTech Connect

    Craig, Nathaniel; Essig, Rouven; Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.

    2012-02-17

    We analyze the phases of supersymmetric chiral gauge theories with an antisymmetric tensor and (anti)fundamental flavors, in the presence of a classically marginal superpotential deformation. Varying the number of flavors that appear in the superpotential reveals rich infrared chiral dynamics and novel dualities. The dualities are characterized by an infinite family of magnetic duals with arbitrarily large gauge groups describing the same fixed point, correlated with arbitrarily large classical global symmetries that are truncated nonperturbatively. At the origin of moduli space, these theories exhibit a phase with confinement and chiral symmetry breaking, an interacting nonabelian Coulomb phase, and phases where an interacting sector coexists with a sector that either s-confines or is in a free magnetic phase. Properties of these intriguing 'mixed phases' are studied in detail using duality and a-maximization, and the presence of superpotential interactions provides further insights into their formation.

  20. Energetic molding of chiral magnetic bubbles

    NASA Astrophysics Data System (ADS)

    Lau, Derek; Sundar, Vignesh; Zhu, Jian-Gang; Sokalski, Vincent

    2016-08-01

    Topologically protected magnetic structures such as skyrmions and domain walls (DWs) have drawn a great deal of attention recently due to their thermal stability and potential for manipulation by spin current, which is the result of chiral magnetic configurations induced by the interfacial Dzyaloshinskii-Moriya interaction (DMI). Designing devices that incorporate DMI necessitates a thorough understanding of how the interaction presents and can be measured. One approach is to measure growth asymmetry of chiral bubble domains in perpendicularly magnetized thin films, which has been described elsewhere by thermally activated DW motion. Here, we demonstrate that the anisotropic angular dependence of DW energy originating from the DMI is critical to understanding this behavior. Domains in Co/Ni multilayers are observed to preferentially grow into nonelliptical teardrop shapes, which vary with the magnitude of an applied in-plane field. We model the domain profile using energetic calculations of equilibrium shape via the Wulff construction, which serves as a new paradigm for describing chiral domains that explains both the teardrop shape and the reversal of growth symmetry at large fields.

  1. Chiral discrimination in optical trapping and manipulation

    NASA Astrophysics Data System (ADS)

    Bradshaw, David S.; Andrews, David L.

    2014-10-01

    When circularly polarized light interacts with chiral molecules or nanoscale particles powerful symmetry principles determine the possibility of achieving chiral discrimination, and the detailed form of electrodynamic mechanisms dictate the types of interaction that can be involved. The optical trapping of molecules and nanoscale particles can be described in terms of a forward-Rayleigh scattering mechanism, with trapping forces being dependent on the positioning within the commonly non-uniform intensity beam profile. In such a scheme, nanoparticles are commonly attracted to local potential energy minima, ordinarily towards the centre of the beam. For achiral particles the pertinent material response property usually entails an electronic polarizability involving transition electric dipole moments. However, in the case of chiral molecules, additional effects arise through the engagement of magnetic counterpart transition dipoles. It emerges that, when circularly polarized light is used for the trapping, a discriminatory response can be identified between left- and right-handed polarizations. Developing a quantum framework to accurately describe this phenomenon, with a tensor formulation to correctly represent the relevant molecular properties, the theory leads to exact analytical expressions for the associated energy landscape contributions. Specific results are identified for liquids and solutions, both for isotropic media and also where partial alignment arises due to a static electric field. The paper concludes with a pragmatic analysis of the scope for achieving enantiomer separation by such methods.

  2. Remote Imaging of Exploration Flight Test-1 (EFT-1) Entry Heating Risk Reduction

    NASA Technical Reports Server (NTRS)

    Schuster, David M.; Horvath, Thomas J.; Schwartz, Richard J.

    2016-01-01

    A Measure of Performance (MOP) identified with an Exploration Flight Test-1 (EFT-1) Multi- Purpose Crew Vehicle (MPCV) Program Flight Test Objective (FTO) (OFT1.091) specified an observation during reentry though external ground-based or airborne assets with thermal detection capabilities. The objective of this FTO was to be met with onboard Developmental Flight Instrumentation (DFI), but the MOP for external observation was intended to provide complementary quantitative data and serve as a risk reduction in the event of anomalous DFI behavior (or failure). Mr. Gavin Mendeck, the Entry, Descent, and Landing (EDL) Phase Engineer for the MPCV Program (Vehicle Integration Office/Systems & Mission Integration) requested a risk-reduction assessment from the NASA Engineering and Safety Center (NESC) to determine whether quantitative imagery could be obtained from remote aerial assets to support the external observation MOP. If so, then a viable path forward was to be determined, risks identified, and an observation pursued. If not, then the MOP for external observation was to be eliminated.

  3. Toward electroweak scale cold dark matter with local dark gauge symmetry and beyond the DM EFT

    NASA Astrophysics Data System (ADS)

    Ko, Pyungwon

    2016-06-01

    In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singlet portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for DM.

  4. Open EFTs, IR effects & late-time resummations: systematic corrections in stochastic inflation

    NASA Astrophysics Data System (ADS)

    Burgess, C. P.; Holman, R.; Tasinato, G.

    2016-01-01

    Though simple inflationary models describe the CMB well, their corrections are often plagued by infrared effects that obstruct a reliable calculation of late-time behaviour. We adapt to cosmology tools designed to address similar issues in other physical systems with the goal of making reliable late-time inflationary predictions. The main such tool is Open EFTs which reduce in the inflationary case to Stochastic Inflation plus calculable corrections. We apply this to a simple inflationary model that is complicated enough to have dangerous IR behaviour yet simple enough to allow the inference of late-time behaviour. We find corrections to standard Stochastic Inflationary predictions for the noise and drift, and we find these corrections ensure the IR finiteness of both these quantities. The late-time probability distribution, {P}(φ ) , for super-Hubble field fluctuations are obtained as functions of the noise and drift and so these too are IR finite. We compare our results to other methods (such as large- N models) and find they agree when these models are reliable. In all cases we can explore in detail we find IR secular effects describe the slow accumulation of small perturbations to give a big effect: a significant distortion of the late-time probability distribution for the field. But the energy density associated with this is only of order H 4 at late times and so does not generate a dramatic gravitational back-reaction.

  5. Comparisons Between Pretest Prediction and Flight Test Data of Aerodynamic Loading for EFT-1

    NASA Technical Reports Server (NTRS)

    Schwing, Alan M.

    2016-01-01

    Exploration Flight Test One (EFT-1) was an incredible milestone in the development NASA's Orion spacecraft. It incorporated hundreds of articles of flight test instrumentation and returned with a wealth of data. Aerodynamic surface pressures were collected during launch vehicle ascent and capsule reentry and descent. These discrete surface pressure measurements enable comparisons to computational results and ground test data. This paper details the comparisons between pre-test predictions and flight test data for the Orion MPCV Crew Module (CM) and Launch Abort Tower (LAT) during all phases of flight. Regions with strong comparisons, poor predictions, and lessons learned are discussed. 38 pressure measurements were made on the LAT during ascent. Nine of the gauges were Honeywell PPTs and the remainder were Kulite pressure transducers. In order to address bias in the Kulites, a two-point linear calibration was used and the details are discussed. Results from the flight are compared to existing database products. 44 pressure measurements were made on the CM during reentry and descent. Nine of the gauges were Honeywell PPTs and the remainder were Kulite pressure transducers. In order to address bias in the Kulites, a tare was made against the vacuum measurements as described below. Once the bias was removed from the gauges, comparisons between predicted loading and the measured results are compared.

  6. Nonperturbative Regulator for Chiral Gauge Theories?

    PubMed

    Grabowska, Dorota M; Kaplan, David B

    2016-05-27

    We propose a nonperturbative gauge-invariant regulator for d-dimensional chiral gauge theories on the lattice. The method involves simulating domain wall fermions in d+1 dimensions with quantum gauge fields that reside on one d-dimensional surface and are extended into the bulk via gradient flow. The result is a theory of gauged fermions plus mirror fermions, where the mirror fermions couple to the gauge fields via a form factor that becomes exponentially soft with the separation between domain walls. The resultant theory has a local d-dimensional interpretation only if the chiral fermion representation is anomaly free. A physical realization of this construction would imply the existence of mirror fermions in the standard model that are invisible except for interactions induced by vacuum topology, and which could gravitate differently than conventional matter. PMID:27284646

  7. Chiral patterning in Paenibacillus colonies under stress

    NASA Astrophysics Data System (ADS)

    Levine, Herbert

    2012-02-01

    One of the most striking examples of bacterial colony patterning occurs in the C-morphotype of Paenibacillus strains. Here, macroscopic chirality results from the interaction of local liquid-crystal ordering of the long bacterial cells with the self-propelled motility driven by the non-reflection-symmetric flagella. This talk will review some of the original experimental data from the Ben-Jacob lab as well as recent insight obtained via genomics. I will then discuss attempts to model and simulate the chiral patterns via solving reaction-diffusion equations on random lattices. At the end, I will introduce the challenges still to be faced in understanding transitions between these patterns and more common branching structures

  8. Analysis of general power counting rules in effective field theory

    NASA Astrophysics Data System (ADS)

    Gavela, Belen; Jenkins, Elizabeth E.; Manohar, Aneesh V.; Merlo, Luca

    2016-09-01

    We derive the general counting rules for a quantum effective field theory (EFT) in {d} dimensions. The rules are valid for strongly and weakly coupled theories, and they predict that all kinetic energy terms are canonically normalized. They determine the energy dependence of scattering cross sections in the range of validity of the EFT expansion. We show that the size of the cross sections is controlled by the Λ power counting of EFT, not by chiral counting, even for chiral perturbation theory (χ PT). The relation between Λ and f is generalized to {d} dimensions. We show that the naive dimensional analysis 4π counting is related to hbar counting. The EFT counting rules are applied to χ PT, low-energy weak interactions, Standard Model EFT and the non-trivial case of Higgs EFT.

  9. Nanoconfinement-Induced Structures in Chiral Liquid Crystals

    PubMed Central

    Melle, Michael; Theile, Madlona; Hall, Carol K.; Schoen, Martin

    2013-01-01

    We employ Monte Carlo simulations in a specialized isothermal-isobaric and in the grand canonical ensemble to study structure formation in chiral liquid crystals as a function of molecular chirality. Our model potential consists of a simple Lennard-Jones potential, where the attractive contribution has been modified to represent the orientation dependence of the interaction between a pair of chiral liquid-crystal molecules. The liquid crystal is confined between a pair of planar and atomically smooth substrates onto which molecules are anchored in a hybrid fashion. Hybrid anchoring allows for the formation of helical structures in the direction perpendicular to the substrate plane without exposing the helix to spurious strains. At low chirality, we observe a cholesteric phase, which is transformed into a blue phase at higher chirality. More specifically, by studying the unit cell and the spatial arrangement of disclination lines, this blue phase can be established as blue phase II. If the distance between the confining substrates and molecular chirality are chosen properly, we see a third structure, which may be thought of as a hybrid, exhibiting mixed features of a cholesteric and a blue phase. PMID:23989605

  10. Chirally modified platinum generated by adsorption of cinchonidine ether derivatives: towards uncovering the chiral sites.

    PubMed

    Bonalumi, Norberto; Vargas, Angelo; Ferri, Davide; Baiker, Alfons

    2007-01-01

    The adsorption behavior of O-methyl and O-trimethylsilyl derivatives of cinchonidine (CD), employed as chiral modifiers for heterogeneous enantioselective hydrogenations on supported Pt catalysts, has been investigated by using attenuated total reflection infrared spectroscopy (ATR-IR) and density functional theory (DFT) electronic structure calculations. The ATR-IR spectroscopic investigation provided detailed insight of the adsorbed modifiers under conditions close to those employed during catalytic processes, and electronic structure calculations were used as a complement to the experiments to uncover the implications of conformational changes in generating the topology of the surface chiral site. The structural investigation of the adsorbed modifiers revealed a relationship between the spatial positions of the ether substituents and the enantiodifferentiation induced by the modified catalyst observed in the hydrogenation of alpha-activated ketones. Experiments and calculations corroborate a model, according to which the addition of a bulky ether group to CD reshapes the chiral sites, thus generating catalytic chiral surfaces with different and, in some cases (e.g. hydrogenation of ketopantolactone), even opposite enantioselective properties to those obtained with CD without altering the absolute configuration of the modifier. The study also confirms that active surface conformations of cinchona modifiers are markedly different from those existing in vacuum and in solution, thus underlying the necessity of investigating the surface-modifier interaction in order to understand enantioselectivity.

  11. Chiral Crystallization of Ethylenediamine Sulfate

    ERIC Educational Resources Information Center

    Koby, Lawrence; Ningappa, Jyothi B.; Dakesssian, Maria; Cuccia, Louis A.

    2005-01-01

    The optimal conditions for the crystallization of achiral ethylenediamine sulfate into large chiral crystals that are ideal for polarimetry studies and observation using Polaroid sheets are presented. This experiment is an ideal undergraduate experiment, which clearly demonstrates the chiral crystallization of an achiral molecule.

  12. CHIRAL PESTICIDES: OCCURRENCE AND SIGNIFICANCE

    EPA Science Inventory

    Like amino acids, certain pesticides exist in "left-handed" and "right-handed" (chiral) forms. Commercially available chiral pesticides are produced as racemic mixtures in which the ratio of the two forms (or enantiomers) is 1:1. Enantiomers have the same ...

  13. Determining Chiral Configuration of Diamines via Contact Angle Measurements on Enantioselective Alanine-Appended Benzene-Tricarboxamide Gelators.

    PubMed

    Jung, Sung Ho; Kim, Ka Young; Ahn, Ahreum; Choi, Myong Yong; Jaworski, Justyn; Jung, Jong Hwa

    2016-06-01

    Spectroscopic techniques exist that may discern between enantiomers and assess chiral purity. A nonspectroscopic approach that may be directly observed could provide numerous benefits. Using chiral alanine-appended benzene-tricarboxamide gelators, we reveal a methanol gel system that is capable of providing visual discrimination between enantiomers of various diamines. Specifically, gelation is induced by supramolecular nanofiber assembly resulting from interaction between a chiral gelator and a diamine of opposing chirality (i.e., a heterochiral system). Upon further implementing the chiral gelator in electrospun fibers as solid state films, we revealed enantioselective surface wetting properties that allowed for determining chirality through contact angle measurements. While these two approaches of observable gelation and surface wetting offer nonspectroscopic approaches, we also find that the supramolecular nanofiber assembly was able to enhance the induced circular dichroism signal resulting from addition of chiral diamines, allowing precise quantification of their enantiomeric purity.

  14. Controlling Chirality of Entropic Crystals

    NASA Astrophysics Data System (ADS)

    Damasceno, Pablo F.; Karas, Andrew S.; Schultz, Benjamin A.; Engel, Michael; Glotzer, Sharon C.

    2015-10-01

    Colloidal crystal structures with complexity and diversity rivaling atomic and molecular crystals have been predicted and obtained for hard particles by entropy maximization. However, thus far homochiral colloidal crystals, which are candidates for photonic metamaterials, are absent. Using Monte Carlo simulations we show that chiral polyhedra exhibiting weak directional entropic forces self-assemble either an achiral crystal or a chiral crystal with limited control over the crystal handedness. Building blocks with stronger faceting exhibit higher selectivity and assemble a chiral crystal with handedness uniquely determined by the particle chirality. Tuning the strength of directional entropic forces by means of particle rounding or the use of depletants allows for reconfiguration between achiral and homochiral crystals. We rationalize our findings by quantifying the chirality strength of each particle, both from particle geometry and potential of mean force and torque diagrams.

  15. Controlling Chirality of Entropic Crystals.

    PubMed

    Damasceno, Pablo F; Karas, Andrew S; Schultz, Benjamin A; Engel, Michael; Glotzer, Sharon C

    2015-10-01

    Colloidal crystal structures with complexity and diversity rivaling atomic and molecular crystals have been predicted and obtained for hard particles by entropy maximization. However, thus far homochiral colloidal crystals, which are candidates for photonic metamaterials, are absent. Using Monte Carlo simulations we show that chiral polyhedra exhibiting weak directional entropic forces self-assemble either an achiral crystal or a chiral crystal with limited control over the crystal handedness. Building blocks with stronger faceting exhibit higher selectivity and assemble a chiral crystal with handedness uniquely determined by the particle chirality. Tuning the strength of directional entropic forces by means of particle rounding or the use of depletants allows for reconfiguration between achiral and homochiral crystals. We rationalize our findings by quantifying the chirality strength of each particle, both from particle geometry and potential of mean force and torque diagrams. PMID:26550757

  16. Fluorescence Turn-on Enantioselective Recognition of both Chiral Acidic Compounds and α-Amino Acids by a Chiral Tetraphenylethylene Macrocycle Amine.

    PubMed

    Feng, Hai-Tao; Zhang, Xing; Zheng, Yan-Song

    2015-08-21

    New chiral tetraphenylethylene (TPE) macrocycles bearing optically pure amine groups were synthesized and found to have a discriminating ability between the two enantiomers of not only chiral acidic compounds but also α-amino acids by enantioselective aggregation and aggregation-induced emission (AIE) effects. NMR spectra, including 2D-NOESY, disclosed that the host-guest interaction of the macrocycle receptor played a key role in addition to the acid-base interactions.

  17. Plasmonic Circular Dichroism of Chiral Nanoparticle Assemblies

    NASA Astrophysics Data System (ADS)

    Fan, Zhiyuan; Zhang, Hui; Govorov, Alexander; Ohio University Team

    2014-03-01

    Plasmonic circular dichroism(CD) of chiral metal nanoparticle(MNP) assemblies in the visible band results from dipolar and multipolar interaction between plasmons on MNPs. Both isotropic and anisotropic CD signals are extremely dimension-sensitive and strongly configuration-dependent. In this presentation, such geometry-dependence of plasmonic CD response will be analytically studied using an expansion of many-dipole interaction of the systems. In the multipole regime, numerical simulations show new features of multipole plasmon interactions. One interesting observation is that a chiral equilateral tetramer made of 4 different NPs shows nearly zero CD response in the point dipole interaction regime but moderately strong CD response from multipole interaction of closely packed NP assemblies. Generally, CD signals of closely packed MNP assemblies are significantly enhanced and more sensitive to the geometric parameters. They can be used in many novel sensing applications as either solid-state or colloidal systems. A.O.G. acknowledges the Science Foundation Ireland. This work was supported by the U.S. Army Research Laboratory and the U.S. Army Research Office under contract/grant number W911NF-12-1-0407 and by the Volkswagen Foundation (Germany).

  18. Chiral Shielding Revisited

    SciTech Connect

    Scadron, M. D.

    2008-08-31

    A model-independent chiral soft-pion theorem (SPT) shields the now observed scalar-meson ground-state isoscalar {sigma}(600) and isospinor {kappa}(800) resonances from detection in a{sub 1}{yields}{pi}({pi}{pi}){sub S-wave}, {gamma}{gamma}{yields}2{pi}{sup 0}, {pi}{sup -}P{yields}{pi}{sup -}{pi}{sup +}n, and K{sup -}P{yields}K{sup -}{pi}{sup +}n processes. Moreover, for pseudoscalar-to-vector-vector (PVV) decays, quark loops only are required.

  19. Sum rules for magnetic moments and polarizabilities in QED and chiral effective-field theory

    SciTech Connect

    Barry Holstein; Vladimir Pascalutsa; Marc Vanderhaeghen

    2005-08-01

    We elaborate on a recently proposed extension of the Gerasimov-Drell-Hearn (GDH) sum rule which is achieved by taking derivatives with respect to the anomalous magnetic moment. The new sum rule features a linear relation between the anomalous magnetic moment and the dispersion integral over a cross-section quantity. We find some analogy of the linearized form of the GDH sum rule with the ''sideways dispersion relations''. As an example, we apply the linear sum rule to reproduce the famous Schwinger's correction to the magnetic moment in QED from a tree-level cross-section calculation and outline the procedure for computing the two-loop correction from a one-loop cross-section calculation. The polarizabilities of the electron in QED are considered as well by using the other forward-Compton-scattering sum rules. We also employ the sum rules to study the magnetic moment and polarizabilities of the nucleon in a relativistic chiral EFT framework. In particular we investigate the chiral extrapolation of these quantities.

  20. Supernovae, neutrinos and the chirality of amino acids.

    PubMed

    Boyd, Richard N; Kajino, Toshitaka; Onaka, Takashi

    2011-01-01

    A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is defined. The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the (14)N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth's proteinaceous amino acids.

  1. Supernovae, Neutrinos and the Chirality of Amino Acids

    PubMed Central

    Boyd, Richard N.; Kajino, Toshitaka; Onaka, Takashi

    2011-01-01

    A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is defined. The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth’s proteinaceous amino acids. PMID:21747686

  2. Stardust, Supernovae and the Chirality of the Amino Acids

    SciTech Connect

    Boyd, R N; Kajino, T; Onaka, T

    2011-03-09

    A mechanism for creating enantiomerism in the amino acids, the building blocks of the proteins, that involves global selection of one chirality by interactions between the amino acids and neutrinos from core-collapse supernovae is described. The selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth's amino acids.

  3. Lagrangians for massive Dirac chiral superfields

    NASA Astrophysics Data System (ADS)

    Jiménez, Enrique; Vaquera-Araujo, C. A.

    2016-06-01

    A variant for the superspin one-half massive superparticle in 4D, N = 1, based on Dirac superfields, is offered. As opposed to the current known models that use spinor chiral superfields, the propagating fields of the supermultiplet are those of the lowest mass dimensions possible: scalar, Dirac and vector fields. Besides the supersymmetric chiral condition, the Dirac superfields are not further constrained, allowing a very straightforward implementation of the path-integral method. The corresponding superpropagators are presented. In addition, an interaction super Yukawa potential, formed by Dirac and scalar chiral superfields, is given in terms of their component fields. The model is first presented for the case of two superspin one-half superparticles related by the charged conjugation operator, but in order to treat the case of neutral superparticles, the Majorana condition on the Dirac superfields is also studied. We compare our proposal with the known models of spinor superfields for the one-half superparticle and show that it is equivalent to them.

  4. Preparation and evaluation of novel chiral stationary phases based on quinine derivatives comprising crown ether moieties.

    PubMed

    Wang, Dongqiang; Zhao, Jianchao; Wu, Haixia; Wu, Haibo; Cai, Jianfeng; Ke, Yanxiong; Liang, Xinmiao

    2015-01-01

    The C9-position of quinine was modified by meta- or para-substituted benzo-18-crown-6, and immobilized on 3-mercaptopropyl-modified silica gel through the radical thiol-ene addition reaction. These two chiral stationary phases were evaluated by chiral acids, amino acids, and chiral primary amines. The crown ether moiety on the quinine anion exchanger provided a ligand-exchange site for primary amino groups, which played an important role in the retention and enantioselectivity for chiral compounds containing primary amine groups. These two stationary phases showed good selectivity for some amino acids. The complex interaction between crown ether and protonated primary amino group was investigated by the addition of inorganic salts such as LiCl, NH4Cl, NaCl, and KCl to the mobile phase. The resolution results showed that the simultaneous interactions between two function moieties (quinine and crown ether) and amino acids were important for the chiral separation.

  5. Entropy-driven formation of chiral nematic phases by computer simulations

    NASA Astrophysics Data System (ADS)

    Dussi, Simone; Dijkstra, Marjolein

    2016-04-01

    Predicting the macroscopic chiral behaviour of liquid crystals from the microscopic chirality of the particles is highly non-trivial, even when the chiral interactions are purely entropic in nature. Here we introduce a novel chiral hard-particle model, namely particles with a twisted polyhedral shape and obtain a stable fully entropy-driven cholesteric phase by computer simulations. By slightly modifying the triangular base of the particle, we are able to switch from a left-handed prolate (calamitic) to a right-handed oblate (discotic) cholesteric phase using the same right-handed twisted particle model. Furthermore, we show that not only prolate and oblate chiral nematic phases, but also other novel entropy-driven phases, namely chiral blue phases, chiral nematic phases featuring both twist and splay deformations, chiral biaxial nematic phases with one of the axes twisted, can be obtained by varying particle biaxiality and chirality. Our results allow to identify general guidelines for the stabilization of these phases.

  6. Entropy-driven formation of chiral nematic phases by computer simulations

    PubMed Central

    Dussi, Simone; Dijkstra, Marjolein

    2016-01-01

    Predicting the macroscopic chiral behaviour of liquid crystals from the microscopic chirality of the particles is highly non-trivial, even when the chiral interactions are purely entropic in nature. Here we introduce a novel chiral hard-particle model, namely particles with a twisted polyhedral shape and obtain a stable fully entropy-driven cholesteric phase by computer simulations. By slightly modifying the triangular base of the particle, we are able to switch from a left-handed prolate (calamitic) to a right-handed oblate (discotic) cholesteric phase using the same right-handed twisted particle model. Furthermore, we show that not only prolate and oblate chiral nematic phases, but also other novel entropy-driven phases, namely chiral blue phases, chiral nematic phases featuring both twist and splay deformations, chiral biaxial nematic phases with one of the axes twisted, can be obtained by varying particle biaxiality and chirality. Our results allow to identify general guidelines for the stabilization of these phases. PMID:27067806

  7. Bilayer four-fold rotationally symmetric subwavelength nanostructures for chirality switching

    NASA Astrophysics Data System (ADS)

    Hor, Yew Li; Khoo, Eng Huat

    2014-09-01

    Chirality effect has been reported from the interaction of light with chiral plasmonic nanostructures. Such nanostructure enhances the chirality response of the chiral molecules and provides a good platform for biochemical sensing. The ability to detect chiral molecules has been a long term goal of biologists and chemist because chirality is inherent in macromolecules such as proteins and DNA in human body. One of the challenging problems is manipulation of the CD spectrum. Here, we investigate the switchable chiral effects of subwavelength nanostructures array with the unit cell makes up of double-layered nanostrips in four-fold rotationally symmetric arrangement. The switchable chirality effect has observed in both plasmonic and Bloch modes when the mutual angle between the first layer and second layer rotates with respect to each other. The magnitude of chirality changes from positive to negative when the mutual angle rotates from 0o to 90o. In the order hand, the nanostructures change from right-handed to left-handed structures without altering the polarization of incident light, or vice versa, upon the mutual rotation angles. Thus, by manipulating the mutual rotation angle, the handedness of the nanostructure will switch and cause the reversal of the outgoing light.

  8. Hyperfine meson splittings: chiral symmetry versus transverse gluon exchange

    SciTech Connect

    Felipe J. Llanes-Estrada; Stephen R. Cotanch; Adam P. Szczepaniak; Eric S. Swanson

    2004-02-01

    Meson spin splittings are examined within an effective Coulomb gauge QCD Hamiltonian incorporating chiral symmetry and a transverse hyperfine interaction necessary for heavy quarks. For light and heavy quarkonium systems the pseudoscalar-vector meson spectrum is generated by approximate BCS-RPA diagonalizations. This relativistic formulation includes both S and D waves for the vector mesons which generates a set of coupled integral equations. A smooth transition from the heavy to the light quark regime is found with chiral symmetry dominating the /pi-/rho mass difference. A good, consistent description of the observed meson spin splittings and chiral quantities, such as the quark condensate and the /pi mass, is obtained. Similar comparisons with TDA diagonalizations, which violate chiral symmetry, are deficient for light pseudoscalar mesons indicating the need to simultaneously include both chiral symmetry and a hyperfine interaction. The /eta{sub b} mass is predicted to be around 9400 MeV consistent with other theoretical expectations and above the unconfirmed 9300 MeV candidate. Finally, for comparison with lattice results, the J reliability parameter is also evaluated.

  9. Chiral Perylene Materials by Ionic Self-Assembly.

    PubMed

    Echue, Geraldine; Hamley, Ian; Lloyd Jones, Guy C; Faul, Charl F J

    2016-09-01

    Two chiral complexes (1-SDS and 1-SDBS) were prepared via the ionic self-assembly of a chiral perylene diimide tecton with oppositely charged surfactants. The effect of surfactant tail architecture on the self-assembly properties and supramolecular structure was investigated in detail using UV-vis, IR, circular dichroism, light microscopy, X-ray diffraction studies, and electron microscopy. The results obtained revealed the molecular chirality of the parent perylene tecton could be translated into supramolecular helical chirality of the resulting complexes via primary ionic interactions through careful choice of solvent and concentration. Differing solvent-dependent aggregation behavior was observed for these complexes as a result of the different possible noncovalent interactions via the surfactant alkyl tails. The results presented in this study demonstrate that ionic self-assembly (ISA) is a facile strategy for the production of chiral supramolecular materials based on perylene diimides. The structure-function relationship is easily explored here due to the wide selection and easy availability of common surfactants. PMID:27486788

  10. Chiral limit of QCD

    SciTech Connect

    Gupta, R.

    1994-12-31

    This talk contains an analysis of quenched chiral perturbation theory and its consequences. The chiral behavior of a number of quantities such as the pion mass m{sub pi}{sup 2}, the Bernard-Golterman ratios R and {sub X}, the masses of nucleons, and the kaon B-parameter are examined to see if the singular terms induced by the additional Goldstone boson, {eta}{prime}, are visible in present data. The overall conclusion (different from that presented at the lattice meeting) of this analysis is that even though there are some caveats attached to the indications of the extra terms induced by {eta}{prime} loops, the standard expressions break down when extrapolating the quenched data with m{sub q} < m{sub s}/2 to physical light quarks. I then show that due to the single and double poles in the quenched {eta}{prime}, the axial charge of the proton cannot be calculated using the Adler-Bell-Jackiw anomaly condition. I conclude with a review of the status of the calculation of light quark masses from lattice QCD.

  11. Interlayer interactions and the dependence of biaxiality of the chiral smectic-C* phase on electric field in the helical unwinding process.

    PubMed

    Song, Jang-Kun; Vij, J K; Kobayashi, Ichiro

    2007-05-01

    We investigate the unwinding process of pure and racemized mixtures of (1-methylheptyloxycarbonyl)phenyl- 4'-carboctyloxy-biphenyl-4-carboxylate (MHPOOCBC) in homeotropic cells by studying (i) the optical texture under crossed polarizers and (ii) the tilted conoscopy as a function of the electric field for different temperatures. The tilted conoscopy yields biaxiality and the tilt angle for values of the latter up to 45 degrees . We find that the unwinding process depends on the optical purity of the sample and the temperature. A cell with pure MHPOOCBC surprisingly exhibits a large positive biaxiality in the initial stages of the unwinding process. The magnitude of the positive biaxiality decreases with a decrease in the enantiomeric excess (EE) of the compound and eventually it becomes negative for a material having a low EE value. The negative biaxiality observed in a mixture with a low EE value is normal and can be explained by a double sine-Gordon equation proposed by Meyer. Microscopic observations show that the special unwinding behavior (positive biaxiality) is related to the helical fractures, that is, to the existence of discretely coiled helical structures. We show that these helical fractures arise from the existence of a narrow energy well in the synclinic position. This implies that the elastic constant near the synclinic position is significantly larger than in other positions. By adopting a semiempirical equation for the interlayer interactions which replaces the conventional equation, we successfully simulate the various unwinding behaviors. We reasonably conclude that the special interlayer interaction is due to the steric interactions between the two adjacent surfaces formed by somewhat tilted terminal parts of the molecules.

  12. Chiral quantum dot based materials

    NASA Astrophysics Data System (ADS)

    Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii

    2014-05-01

    Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.

  13. Nonperturbative NN scattering in {sup 3}S{sub 1}–{sup 3}D{sub 1} channels of EFT(⁄π)

    SciTech Connect

    Yang, Ji-Feng

    2013-12-15

    The closed-form T matrices in the {sup 3}S{sub 1}–{sup 3}D{sub 1} channels of EFT(⁄π) for NN scattering with the potentials truncated at order O(Q{sup 4}) are presented with the nonperturbative divergences parametrized in a general manner. The stringent constraints imposed by the closed form of the T matrices are exploited in the underlying theory perspective and turned into virtues in the implementation of subtractions and the manifestation of power counting rules in nonperturbative regimes, leading us to the concept of EFT scenario. A number of scenarios of the EFT description of NN scattering are compared with PSA data in terms of effective range expansion and {sup 3}S{sub 1} phase shifts, showing that it is favorable to proceed in a scenario with conventional EFT couplings and sophisticated renormalization in order to have large NN scattering lengths. The informative utilities of fine tuning are demonstrated in several examples and naturally interpreted in the underlying theory perspective. In addition, some of the approaches adopted in the recent literature are also addressed in the light of EFT scenario. -- Highlights: •Closed-form unitary T matrices for NN scattering are obtained in EFT(⁄π). •Nonperturbative properties inherent in such closed-form T matrices are explored. •Nonperturbative renormalization is implemented through exploiting these properties. •Unconventional power counting of couplings is shown to be less favored by PSA data. •The ideas about nonperturbative renormalization here might have wider applications.

  14. Higgs physics beyond the SM: The non-linear EFT approach

    NASA Astrophysics Data System (ADS)

    Brivio, I.

    2016-07-01

    Depending on whether electroweak physics beyond the Standard Model is based on a linear or on a non-linear implementation of the electroweak symmetry breaking, a linear or a chiral Effective Lagrangian is more appropriate. In this talk, the main low-energy signals that allow to recognize whether the observed Higgs scalar is a dynamical (composite) particle or rather an elementary one are presented, in a model-independent way. The patterns of effective couplings produced upon the assumption of specific composite Higgs models are also discussed.=1

  15. Consistent quantization of massive chiral electrodynamics in four dimensions

    SciTech Connect

    Andrianov, A. ); Bassetto, A.; Soldati, R.

    1989-10-09

    We discuss the quantization of a four-dimensional model in which a massive Abelian vector field interacts with chiral massless fermions. We show that, by introducing extra scalar fields, a renormalizable unitary {ital S} matrix can be obtained in a suitably defined Hilbert space of physical states.

  16. Amino Acids and Chirality

    NASA Technical Reports Server (NTRS)

    Cook, Jamie E.

    2012-01-01

    Amino acids are among the most heavily studied organic compound class in carbonaceous chondrites. The abundance, distributions, enantiomeric compositions, and stable isotopic ratios of amino acids have been determined in carbonaceous chondrites fi'om a range of classes and petrographic types, with interesting correlations observed between these properties and the class and typc of the chondritcs. In particular, isomeric distributions appear to correlate with parent bodies (chondrite class). In addition, certain chiral amino acids are found in enantiomeric excess in some chondrites. The delivery of these enantiomeric excesses to the early Earth may have contributed to the origin of the homochirality that is central to life on Earth today. This talk will explore the amino acids in carbonaceous chondritcs and their relevance to the origin of life.

  17. Electroproduction of pions at threshold in chiral perturbation theory

    SciTech Connect

    Lee, T.S.H.; Bernard, V.; Kaiser, N.; Meissner, U.G.

    1995-08-01

    The electroproduction of pions off protons close to threshold is studied within the framework of baryon chiral perturbation theory. The approach is based on the fundamental QCD property that at low energies the strong interactions are dictated by the spontaneously broken chiral symmetry. The calculation was done up to the 1-loop level by carrying out order-by-order renormalization procedures. A thorough study of the low-energy theorems related to electroproduction of pions was carried out. Our study showed how the axial radius of the nucleon can be related to the S-wave multipoles E{sub 0+}{sup (-)} and L{sub 0+}{sup (-)}.

  18. Confined chiral polymer nematics: Ordering and spontaneous condensation

    NASA Astrophysics Data System (ADS)

    Svenšek, Daniel; Podgornik, Rudolf

    2012-12-01

    We investigate condensation of a long confined chiral nematic polymer inside a spherical enclosure, mimicking condensation of DNA inside a viral capsid. The Landau-de Gennes nematic free-energy Ansatz appropriate for nematic polymers allows us to study the condensation process in detail with different boundary conditions at the enclosing wall that simulate repulsive and attractive polymer-surface interactions. By increasing the chirality, we observe a transformation of the toroidal condensate into a closed surface with an increasing genus, in some respects akin to the ordered domain formation observed in cryo-microscopy of bacteriophages.

  19. Chiral Bosonization of Superconformal Ghosts

    NASA Technical Reports Server (NTRS)

    Shi, Deheng; Shen, Yang; Liu, Jinling; Xiong, Yongjian

    1996-01-01

    We explain the difference of the Hilbert space of the superconformal ghosts (beta,gamma) system from that of its bosonized fields phi and chi. We calculate the chiral correlation functions of phi, chi fields by inserting appropriate projectors.

  20. Life's chirality from prebiotic environments

    NASA Astrophysics Data System (ADS)

    Gleiser, Marcelo; Walker, Sara Imari

    2012-10-01

    A key open question in the study of life is the origin of biomolecular homochirality: almost every life-form on Earth has exclusively levorotary amino acids and dextrorotary sugars. Will the same handedness be preferred if life is found elsewhere? We review some of the pertinent literature and discuss recent results suggesting that life's homochirality resulted from sequential chiral symmetry breaking triggered by environmental events. In one scenario, autocatalytic prebiotic reactions undergo stochastic fluctuations due to environmental disturbances, in a mechanism reminiscent of evolutionary punctuated equilibrium: short-lived destructive events may lead to long-term enantiomeric excess. In another, chiral-selective polymerization reaction rates influenced by environmental effects lead to substantial chiral excess even in the absence of autocatalysis. Applying these arguments to other potentially life-bearing platforms has implications to the search for extraterrestrial life: we predict that a statistically representative sampling of extraterrestrial stereochemistry will be racemic (chirally neutral) on average.

  1. Processing Near-Infrared Imagery of the Orion Heatshield During EFT-1 Hypersonic Reentry

    NASA Technical Reports Server (NTRS)

    Spisz, Thomas S.; Taylor, Jeff C.; Gibson, David M.; Kennerly, Steve; Osei-Wusu, Kwame; Horvath, Thomas J.; Schwartz, Richard J.; Tack, Steven; Bush, Brett C.; Oliver, A. Brandon

    2016-01-01

    The Scientifically Calibrated In-Flight Imagery (SCIFLI) team captured high-resolution, calibrated, near-infrared imagery of the Orion capsule during atmospheric reentry of the EFT-1 mission. A US Navy NP-3D aircraft equipped with a multi-band optical sensor package, referred to as Cast Glance, acquired imagery of the Orion capsule's heatshield during a period when Orion was slowing from approximately Mach 10 to Mach 7. The line-of-sight distance ranged from approximately 65 to 40 nmi. Global surface temperatures of the capsule's thermal heatshield derived from the near-infrared intensity measurements complemented the in-depth (embedded) thermocouple measurements. Moreover, these derived surface temperatures are essential to the assessment of the thermocouples' reliance on inverse heat transfer methods and material response codes to infer the surface temperature from the in-depth measurements. The paper describes the image processing challenges associated with a manually-tracked, high-angular rate air-to-air observation. Issues included management of significant frame-to-frame motions due to both tracking jerk and jitter as well as distortions due to atmospheric effects. Corrections for changing sky backgrounds (including some cirrus clouds), atmospheric attenuation, and target orientations and ranges also had to be made. The image processing goal is to reduce the detrimental effects due to motion (both sensor and capsule), vibration (jitter), and atmospherics for image quality improvement, without compromising the quantitative integrity of the data, especially local intensity (temperature) variations. The paper will detail the approach of selecting and utilizing only the highest quality images, registering several co-temporal image frames to a single image frame to the extent frame-to-frame distortions would allow, and then co-adding the registered frames to improve image quality and reduce noise. Using preflight calibration data, the registered and averaged

  2. QCD chiral transition temperature in a Dyson-Schwinger-equation context

    SciTech Connect

    Blank, M.; Krassnigg, A.

    2010-08-01

    We analyze the chiral phase transition with the help of the QCD gap equation. Various models for the effective interaction in rainbow truncation are contrasted with regard to the resulting chiral transition temperatures. In particular, we investigate possible systematic relations of the details of the effective interaction and the value of T{sub c}. In addition, we quantify changes to the transition temperature beyond the rainbow truncation.

  3. Rotation of the chiral bag

    NASA Astrophysics Data System (ADS)

    Kahana, David E.; Jackson, A. D.; Ripka, G.

    1986-11-01

    Cranking of the chiral bag model is carried out in order to generate the correct quantum numbers for SU(2) baryons. The moment of inertia of the system is found to be divided between the meson and quark sectors. A numerical evaluation of the contributions to the moment of inertia from valence quarks and from mesons is presented. Finally, a discussion is given of the nucleon-delta mass splitting predicted in the chiral bag model.

  4. Gluons in the chiral bag

    NASA Astrophysics Data System (ADS)

    Kahana, D. E.; Milana, J.

    1987-07-01

    A perturbative QCD calculation of gluon exchange corrections to the cranking moment of inertia of the chiral bag model is done using the full time-dependent cavity propagators. Cranking is used to construct the nucleon and delta states and a value of the effective strong coupling constant is extracted by fitting the empirical Δ N mass splitting. The MIT bag limit (large bag radius) of the chiral bag model is also examined.

  5. Inhomogeneous chiral symmetry breaking in dense neutron-star matter

    NASA Astrophysics Data System (ADS)

    Buballa, Michael; Carignano, Stefano

    2016-03-01

    An increasing number of model results suggests that chiral symmetry is broken inhomogeneously in a certain window at intermediate densities in the QCD phase diagram. This could have significant effects on the properties of compact stars, possibly leading to new astrophysical signatures. In this contribution we discuss this idea by reviewing recent results on inhomogeneous chiral symmetry breaking under an astrophysics-oriented perspective. After introducing two commonly studied spatial modulations of the chiral condensate, the chiral density wave and the real kink crystal, we focus on their properties and their effect on the equation of state of quark matter. We also describe how these crystalline phases are affected by different elements which are required for a realistic description of a compact star, such as charge neutrality, the presence of magnetic fields, vector interactions and the interplay with color superconductivity. Finally, we discuss possible signatures of inhomogeneous chiral symmetry breaking in the core of compact stars, considering the cases of mass-radius relations and neutrino emissivity explicitly.

  6. Chiral spin liquids in arrays of spin chains

    NASA Astrophysics Data System (ADS)

    Gorohovsky, Gregory; Pereira, Rodrigo G.; Sela, Eran

    2015-06-01

    We describe a coupled-chain construction for chiral spin liquids in two-dimensional spin systems. Starting from a one-dimensional zigzag spin chain and imposing SU(2) symmetry in the framework of non-Abelian bosonization, we first show that our approach faithfully describes the low-energy physics of an exactly solvable model with a three-spin interaction. Generalizing the construction to the two-dimensional case, we obtain a theory that incorporates the universal properties of the chiral spin liquid predicted by Kalmeyer and Laughlin: charge-neutral edge states, gapped spin-1/2 bulk excitations, and ground-state degeneracy on the torus signaling the topological order of this quantum state. In addition, we show that the chiral spin liquid phase is more easily stabilized in frustrated lattices containing corner-sharing triangles, such as the extended kagome lattice, than in the triangular lattice. Our field-theoretical approach invites generalizations to more exotic chiral spin liquids and may be used to assess the existence of the chiral spin liquid as the ground state of specific lattice systems.

  7. Ternary superlattice boosting interface-stabilized magnetic chirality

    SciTech Connect

    Chen, Gong; Schmid, Andreas K.; N'Diaye, Alpha T.; Wu, Yizheng

    2015-02-09

    In cobalt-nickel multilayers grown on iridium surfaces, magnetic homo-chirality can be stabilized by Dzyaloshinskii-Moriya interactions (DMI) at the interface with the substrate. When thickness of the multilayers is increased beyond threshold values, then non-chiral bulk properties exceed interface contributions and this type of chirality vanishes. Here, we use spin-polarized low energy electron microscopy to measure these thickness thresholds, and we determine estimates of the strength of the DMI from the measurements. Even though the same 5d heavy metal is used as a substrate, a remarkably large variation is found between the two 3d magnets: our results indicate that the strength of the DMI at Co/Ir interfaces is three times larger than at Ni/Ir interfaces. We show how this finding provides ways to extend interfacial-DMI stabilization of domain wall chirality to 3d/5d/3d ternary multilayers such as [Ni/Ir/Co]{sub n}. Such strategies may extend chirality-control to larger film thickness and a wider range of substrates, which may be useful for designing new spintronics devices.

  8. Invariant regularization of anomaly-free chiral theories

    NASA Astrophysics Data System (ADS)

    Chang, Lay Nam; Soo, Chopin

    1997-02-01

    We present a generalization of the Frolov-Slavnov invariant regularization scheme for chiral fermion theories in curved spacetimes. The Lagrangian level regularization is explicitly invariant under all the local gauge symmetries of the theory, including local Lorentz invariance. The perturbative scheme works for arbitrary representations which satisfy the chiral gauge anomaly and the mixed Lorentz-gauge anomaly cancellation conditions. Anomalous theories on the other hand manifest themselves by having divergent fermion loops which remain unregularized by the scheme. Since the invariant scheme is promoted to include also local Lorentz invariance, spectator fields which do not couple to gravity cannot be, and are not, introduced. Furthermore, the scheme is truly chiral (Weyl) in that all fields, including the regulators, are left handed; and only the left-handed spin connection is needed. The scheme is, therefore, well suited for the study of the interaction of matter with all four known forces in a completely chiral fashion. In contrast with the vectorlike formulation, the degeneracy between the Adler-Bell-Jackiw current and the fermion number current in the bare action is preserved by the chiral regularization scheme.

  9. Electrolyte effects on the chiral induction and on its temperature dependence in a chiral nematic lyotropic liquid crystal.

    PubMed

    Dawin, Ute C; Osipov, Mikhail A; Giesselmann, Frank

    2010-08-19

    We present a study on the effect of added CsCl and of temperature variation on the chiral induction in a chiral nematic lyotropic liquid crystal (LC) composed of the surfactant cesium perfluorooctanoate (CsPFO), water, and the chiral dopant d-Leucine (d-Leu). The chiral induction was measured as the helical pitch P. The role of the additives CsCl and d-Leu on the phase behavior is investigated and discussed. The thermal stabilization effect of CsCl is shown to lead to an apparent salt effect on the pitch when the pitch is compared at a constant temperature. This apparent effect is removed by comparing the pitch measured for different salt concentrations at a temperature relative to the phase-transition temperatures; thus, the real salt effect on the pitch is described. High salt concentrations are shown to increase the pitch, that is, hinder the chiral induction. The effect is discussed in terms of a decreased solubilization of the amphiphilic chiral solute d-Leu in the micelles due to the salt-induced screening of the surfactant head groups and the consequential denser packing of the surfactants. The temperature variation of the pitch is investigated for all CsCl concentrations and is found to be essentially independent of the salt concentration. The temperature variation is analyzed and discussed in the context of a theoretical model taking into account specific properties of lyotropic liquid crystals. A hyperbolic decrease of the pitch is found with increasing temperature, which is known, from thermotropic liquid crystals, to stem from pretransitional critical fluctuations close to the lamellar phase. However, the experimental data confirmed the theoretical prediction that, at high temperature, that is, far away from the transition into the lamellar phase, the pitch is characterized by a linear temperature dependence which is determined by a combination of steric and dispersion chiral interactions. The parameters of the theoretical expression for the pitch have

  10. Chirality-selected phase behaviour in ionic polypeptide complexes

    PubMed Central

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, Charles F.; Margossian, Khatcher O.; Whitmer, Jonathan K.; Qin, Jian; de Pablo, Juan J.; Tirrell, Matthew

    2015-01-01

    Polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with a β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation. PMID:25586861

  11. Ballistic rectification of vortex domain wall chirality at nanowire corners

    SciTech Connect

    Omari, K.; Bradley, R. C.; Broomhall, T. J.; Hodges, M. P. P.; Hayward, T. J.; Rosamond, M. C.; Linfield, E. H.; Im, M.-Y.; Fischer, P.

    2015-11-30

    The interactions of vortex domain walls with corners in planar magnetic nanowires are probed using magnetic soft X-ray transmission microscopy. We show that when the domain walls are propagated into sharp corners using applied magnetic fields above a critical value, their chiralities are rectified to either clockwise or anticlockwise circulation depending on whether the corners turn left or right. Single-shot focused magneto-optic Kerr effect measurements are then used to demonstrate how, when combined with modes of domain propagation that conserve vortex chirality, this allows us to dramatically reduce the stochasticity of domain pinning at artificial defect sites. Our results provide a tool for controlling domain wall chirality and pinning behavior both in further experimental studies and in future domain wall-based memory, logic and sensor technologies.

  12. Nondipole Effects in Chiral Systems Measured with Linearly Polarized Light

    NASA Astrophysics Data System (ADS)

    Bowen, K. P.; Hemmers, O.; Guillemin, R.; Stolte, W. C.; Piancastelli, M. N.; Lindle, D. W.

    2015-06-01

    With the advent of third-generation synchrotron light sources, it has been demonstrated that higher-order corrections to the dipole approximation are necessary for the description of light-matter interactions in the soft x-ray range. These effects, known as 'nondipole effects', present themselves as asymmetries in the angular distributions of photoelectrons. Chiral molecules, known to have asymmetries in photoelectron angular distributions when exposed to circularly polarized light, have been proposed to demonstrate a chiral-specific nondipole effect when exposed to linearly polarized light. We present the first-ever measurement of nondipole chiral angular distributions for the case of each enantiomer of camphor in the photon energy range 296-343eV.

  13. Chirality Quantum Phase Transition in Noncommutative Dirac Oscillator

    NASA Astrophysics Data System (ADS)

    Wang, Shao-Hua; Hou, Yu-Long; Wang, Qing; Long, Zheng-Wen; Jing, Jian

    2014-12-01

    The charged Dirac oscillator on a noncommutative plane coupling to a uniform perpendicular magnetic held is studied in this paper. We map the noncommutative plane to a commutative one by means of Bopp shift and study this problem on the commutative plane. We find that this model can be mapped onto a quantum optics model which contains Anti—Jaynes—Cummings (AJC) or Jaynes—Cummings (JC) interactions when a dimensionless parameter ζ (which is the function of the intensity of the magnetic held) takes values in different regimes. Furthermore, this model behaves as experiencing a chirality quantum phase transition when the dimensionless parameter ζ approaches the critical point. Several evidences of the chirality quantum phase transition are presented. We also study the non-relativistic limit of this model and find that a similar chirality quantum phase transition takes place in its non-relativistic limit.

  14. Stereoselective binding of chiral drugs to plasma proteins

    PubMed Central

    Shen, Qi; Wang, Lu; Zhou, Hui; Jiang, Hui-di; Yu, Lu-shan; Zeng, Su

    2013-01-01

    Chiral drugs show distinct biochemical and pharmacological behaviors in the human body. The binding of chiral drugs to plasma proteins usually exhibits stereoselectivity, which has a far-reaching influence on their pharmacological activities and pharmacokinetic profiles. In this review, the stereoselective binding of chiral drugs to human serum albumin (HSA), α1-acid glycoprotein (AGP) and lipoprotein, three most important proteins in human plasma, are detailed. Furthermore, the application of AGP variants and recombinant fragments of HSA for studying enantiomer binding properties is also discussed. Apart from the stereoselectivity of enantiomer-protein binding, enantiomer-enantiomer interactions that may induce allosteric effects are also described. Additionally, the techniques and methods used to determine drug-protein binding parameters are briefly reviewed. PMID:23852086

  15. Dissipative vibrational model for chiral recognition in olfaction

    NASA Astrophysics Data System (ADS)

    Tirandaz, Arash; Taher Ghahramani, Farhad; Shafiee, Afshin

    2015-09-01

    We examine the olfactory discrimination of left- and right-handed enantiomers of chiral odorants based on the odorant-mediated electron transport from a donor to an acceptor of the olfactory receptors embodied in a biological environment. The chiral odorant is effectively described by an asymmetric double-well potential whose minima are associated to the left- and right-handed enantiomers. The introduced asymmetry is considered an overall measure of chiral interactions. The biological environment is conveniently modeled as a bath of harmonic oscillators. The resulting spin-boson model is adapted by a polaron transformation to derive the corresponding Born-Markov master equation with which we obtain the elastic and inelastic electron tunneling rates. We show that the inelastic tunneling through left- and right-handed enantiomers occurs with different rates. The discrimination mechanism depends on the ratio of tunneling frequency to localization frequency.

  16. Chirality-selected phase behaviour in ionic polypeptide complexes

    SciTech Connect

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, III, Charles F.; Margossian, Khatcher O.; Whitmer, Jonathan K.; Qin, Jian; de Pablo, Juan J.; Tirrell, Matthew

    2015-01-14

    In this study, polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with a β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.

  17. Chirality-selected phase behaviour in ionic polypeptide complexes

    DOE PAGES

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; Kade, Matthew J.; Priftis, Dimitrios; Black, Katie A.; Wong, Derek; Klein, Ryan A.; Pierce, III, Charles F.; Margossian, Khatcher O.; et al

    2015-01-14

    In this study, polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with amore » β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.« less

  18. DNA induced chirality and helical twist in achiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Garvey, Alfred; Basu, Rajratan; Kinnamon, Daniel

    A small quantity of DNA sample (Deoxyribonucleic acid -cellulose double-stranded from calf thymus DNA in lyophilized powder form) was doped in an achiral liquid crystal (LC), and the mixture was found to exhibit a weak degree of chirality. The induced chirality in the LC was probed by means of the electroclinic effect in the LC's smectic-A phase, which showed significant pretransitional behavior on approaching the smectic- A-smectic- C transition temperature from above. The same DNA was doped in an achiral nematic LC and the mixture was found to exhibit an average mechanical twist over macroscopic dimensions. The double-stranded DNA-induced chiral pitch length P was determined by measuring the radius of curvature of reverse twist disclination lines in 90o nematic twist cells. In the LC +DNA mixture, the LC's benzene rings interact with the nucleobases of the DNA through π - π stacking, which induces a molecular conformational deracemization in the LC.

  19. Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Boulle, Olivier; Vogel, Jan; Yang, Hongxin; Pizzini, Stefania; de Souza Chaves, Dayane; Locatelli, Andrea; Menteş, Tevfik Onur; Sala, Alessandro; Buda-Prejbeanu, Liliana D.; Klein, Olivier; Belmeguenai, Mohamed; Roussigné, Yves; Stashkevich, Andrey; Chérif, Salim Mourad; Aballe, Lucia; Foerster, Michael; Chshiev, Mairbek; Auffret, Stéphane; Miron, Ioan Mihai; Gaudin, Gilles

    2016-05-01

    Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometre size and the fact that they can be moved by small current densities have opened a new paradigm for the manipulation of magnetization at the nanoscale. Chiral skyrmion structures have so far been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films, and under an external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral Néel internal structure, which we explain as due to the large strength of the Dzyaloshinskii–Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions.

  20. Optical properties of chiral nanostructures

    NASA Astrophysics Data System (ADS)

    Cecilia, Noguez; Román-Velázquez, Carlos E.; Garzón, Ignacio L.

    2004-03-01

    We present a computational model to study the optical properties chiral nanostructures[1] . In this work the nanostructures of interest are composed by N atoms, where each one is represented by a polarizable point dipole located at theposition of the atom. We assume that the dipole located is characterized by a polarizability. The nanostructure is excited by a circularly polarized incident wave, such that, each dipole is subject to a total electric field due to: (i) the incident radiation field, plus (ii) the radiation field resulting from all of the other induced dipoles. Once we solve the complex-linear equations, the dipole moment on each atom in the cluster can be determined and we can find the extinction cross section of the whole nanoparticle. Circular dichroism (CD) spectra of chiral bare and thiol-passivated gold nanoclusters have been calculated within the dipole approximation. The calculated CD spectra show features that allow us to distinguish between clusters with different indexes of chirality. The main factor responsible of the differences in the CD lineshapes is the distribution of interatomic distances that characterize the chiral cluster geometry. These results provide theoretical support for the quantification of chirality and its measurement, using the CD lineshapes of chiral metal nanoclusters. [1] C. E. Roman-Velazquez, et al., J. of Phys. Chem. B (Letter) 107, 12035 (2003) This work has been partly supported by DGAPA-UNAM grants No. IN104201 and IN104402, and by CONACyT grant 36651-E.

  1. Chirality of 4,4'-Biphenylene Bridged Polybissilsesquioxane Nanotubes Using the Dipeptides Derived from Valine.

    PubMed

    Sang, Yunsen; Guo, Yongmin; Wang, Hairui; Li, Yi; Li, Baozong; Yang, Yonggang

    2015-03-01

    Four dipeptides with alkyl chains derived from L- and D-valines were synthesized, the handedness of their self-assemblies were controlled by the valine chirality at the terminals. The stacking of the carbonyl groups plays an important in the formation of chiral organic self-assemblies. Chiral 4,4'-biphenylene bridged polybissilsesquioxane nanotubes were prepared using the self-assemblies of these dipeptides as the templates. The chirality of the polysilsesquioxane nanotubes was mainly controlled by the valines at the terminals of the dipeptides, which was transferred from the valines at the terminals through electrostatic interaction. The valines near the alkyl chains could also affect the polysilsesquioxane chirality through hydrogen bonding.

  2. Chiral resolution of spin angular momentum in linearly polarized and unpolarized light.

    PubMed

    Hernández, R J; Mazzulla, A; Provenzano, C; Pagliusi, P; Cipparrone, G

    2015-11-20

    Linearly polarized (LP) and unpolarized (UP) light are racemic entities since they can be described as superposition of opposite circularly polarized (CP) components of equal amplitude. As a consequence they do not carry spin angular momentum. Chiral resolution of a racemate, i.e. separation of their chiral components, is usually performed via asymmetric interaction with a chiral entity. In this paper we provide an experimental evidence of the chiral resolution of linearly polarized and unpolarized Gaussian beams through the transfer of spin angular momentum to chiral microparticles. Due to the interplay between linear and angular momentum exchange, basic manipulation tasks, as trapping, spinning or orbiting of micro-objects, can be performed by light with zero helicity. The results might broaden the perspectives for development of miniaturized and cost-effective devices.

  3. Chiral resolution of spin angular momentum in linearly polarized and unpolarized light.

    PubMed

    Hernández, R J; Mazzulla, A; Provenzano, C; Pagliusi, P; Cipparrone, G

    2015-01-01

    Linearly polarized (LP) and unpolarized (UP) light are racemic entities since they can be described as superposition of opposite circularly polarized (CP) components of equal amplitude. As a consequence they do not carry spin angular momentum. Chiral resolution of a racemate, i.e. separation of their chiral components, is usually performed via asymmetric interaction with a chiral entity. In this paper we provide an experimental evidence of the chiral resolution of linearly polarized and unpolarized Gaussian beams through the transfer of spin angular momentum to chiral microparticles. Due to the interplay between linear and angular momentum exchange, basic manipulation tasks, as trapping, spinning or orbiting of micro-objects, can be performed by light with zero helicity. The results might broaden the perspectives for development of miniaturized and cost-effective devices. PMID:26585284

  4. Chiral optical response of planar and symmetric nanotrimers enabled by heteromaterial selection

    NASA Astrophysics Data System (ADS)

    Banzer, Peter; Woźniak, Paweł; Mick, Uwe; de Leon, Israel; Boyd, Robert W.

    2016-10-01

    Chirality is an intriguing property of certain molecules, materials or artificial nanostructures, which allows them to interact with the spin angular momentum of the impinging light field. Due to their chiral geometry, they can distinguish between left- and right-hand circular polarization states or convert them into each other. Here we introduce an approach towards optical chirality, which is observed in individual two-dimensional and geometrically mirror-symmetric nanostructures. In this scheme, the chiral optical response is induced by the chosen heterogeneous material composition of a particle assembly and the corresponding resonance behaviour of the constituents it is built from, which breaks the symmetry of the system. As a proof of principle, we investigate such a structure composed of individual silicon and gold nanoparticles both experimentally, as well as numerically. Our proposed concept constitutes an approach for designing two-dimensional chiral media tailored at the nanoscale, allowing for high tunability of their optical response.

  5. Chiral optical response of planar and symmetric nanotrimers enabled by heteromaterial selection

    PubMed Central

    Banzer, Peter; Woźniak, Paweł; Mick, Uwe; De Leon, Israel; Boyd, Robert W.

    2016-01-01

    Chirality is an intriguing property of certain molecules, materials or artificial nanostructures, which allows them to interact with the spin angular momentum of the impinging light field. Due to their chiral geometry, they can distinguish between left- and right-hand circular polarization states or convert them into each other. Here we introduce an approach towards optical chirality, which is observed in individual two-dimensional and geometrically mirror-symmetric nanostructures. In this scheme, the chiral optical response is induced by the chosen heterogeneous material composition of a particle assembly and the corresponding resonance behaviour of the constituents it is built from, which breaks the symmetry of the system. As a proof of principle, we investigate such a structure composed of individual silicon and gold nanoparticles both experimentally, as well as numerically. Our proposed concept constitutes an approach for designing two-dimensional chiral media tailored at the nanoscale, allowing for high tunability of their optical response. PMID:27734960

  6. Chiral resolution of spin angular momentum in linearly polarized and unpolarized light

    PubMed Central

    Hernández, R. J.; Mazzulla, A.; Provenzano, C.; Pagliusi, P.; Cipparrone, G.

    2015-01-01

    Linearly polarized (LP) and unpolarized (UP) light are racemic entities since they can be described as superposition of opposite circularly polarized (CP) components of equal amplitude. As a consequence they do not carry spin angular momentum. Chiral resolution of a racemate, i.e. separation of their chiral components, is usually performed via asymmetric interaction with a chiral entity. In this paper we provide an experimental evidence of the chiral resolution of linearly polarized and unpolarized Gaussian beams through the transfer of spin angular momentum to chiral microparticles. Due to the interplay between linear and angular momentum exchange, basic manipulation tasks, as trapping, spinning or orbiting of micro-objects, can be performed by light with zero helicity. The results might broaden the perspectives for development of miniaturized and cost-effective devices. PMID:26585284

  7. Spontaneous chiral resolution in two-dimensional systems of patchy particles.

    PubMed

    Martínez-González, J A; Chapela, G A; Quintana-H, J

    2014-05-21

    Short ranged potentials and their anisotropy produce spontaneous chiral resolution in a two dimensional model of patchy particles introduced in this paper. This model could represent an equimolar binary mixture (racemic mixture) of two kinds of chiral molecules (enantiomers) adsorbed to a bi-dimensional domain where only lateral short ranged interactions are present. Most racemic mixtures undergo chiral resolution due to their spatial anisotropy, the combined effect of long range forces and the thermodynamic conditions. The patchy particles are modeled as a hard disk and four different bonding sites located to produce chirality. Phase behavior and structural properties are analysed using Discontinuous Molecular Dynamics in the canonical ensemble. When the four patchy particles are separated by the angles {60°, 120°, 60°, 120°}, spontaneous chiral resolution is produced, given by the formation of homochiral clusters, if started from the corresponding racemic mixture. Gel behavior is also obtained in all the systems for low temperatures and low densities. PMID:24852548

  8. Spontaneous chiral resolution in two-dimensional systems of patchy particles

    SciTech Connect

    Martínez-González, J. A.; Chapela, G. A.; Quintana-H, J.

    2014-05-21

    Short ranged potentials and their anisotropy produce spontaneous chiral resolution in a two dimensional model of patchy particles introduced in this paper. This model could represent an equimolar binary mixture (racemic mixture) of two kinds of chiral molecules (enantiomers) adsorbed to a bi-dimensional domain where only lateral short ranged interactions are present. Most racemic mixtures undergo chiral resolution due to their spatial anisotropy, the combined effect of long range forces and the thermodynamic conditions. The patchy particles are modeled as a hard disk and four different bonding sites located to produce chirality. Phase behavior and structural properties are analysed using Discontinuous Molecular Dynamics in the canonical ensemble. When the four patchy particles are separated by the angles (60°, 120°, 60°, 120°), spontaneous chiral resolution is produced, given by the formation of homochiral clusters, if started from the corresponding racemic mixture. Gel behavior is also obtained in all the systems for low temperatures and low densities.

  9. Bottom-up synthesis of chiral covalent organic frameworks and their bound capillaries for chiral separation

    PubMed Central

    Qian, Hai-Long; Yang, Cheng-Xiong; Yan, Xiu-Ping

    2016-01-01

    Covalent organic frameworks (COFs) are a novel class of porous materials, and offer great potential for various applications. However, the applications of COFs in chiral separation and chiral catalysis are largely underexplored due to the very limited chiral COFs available and their challenging synthesis. Here we show a bottom-up strategy to construct chiral COFs and an in situ growth approach to fabricate chiral COF-bound capillary columns for chiral gas chromatography. We incorporate the chiral centres into one of the organic ligands for the synthesis of the chiral COFs. We subsequently in situ prepare the COF-bound capillary columns. The prepared chiral COFs and their bound capillary columns give high resolution for the separation of enantiomers with excellent repeatability and reproducibility. The proposed strategy provides a promising platform for the synthesis of chiral COFs and their chiral separation application. PMID:27401541

  10. Bottom-up synthesis of chiral covalent organic frameworks and their bound capillaries for chiral separation

    NASA Astrophysics Data System (ADS)

    Qian, Hai-Long; Yang, Cheng-Xiong; Yan, Xiu-Ping

    2016-07-01

    Covalent organic frameworks (COFs) are a novel class of porous materials, and offer great potential for various applications. However, the applications of COFs in chiral separation and chiral catalysis are largely underexplored due to the very limited chiral COFs available and their challenging synthesis. Here we show a bottom-up strategy to construct chiral COFs and an in situ growth approach to fabricate chiral COF-bound capillary columns for chiral gas chromatography. We incorporate the chiral centres into one of the organic ligands for the synthesis of the chiral COFs. We subsequently in situ prepare the COF-bound capillary columns. The prepared chiral COFs and their bound capillary columns give high resolution for the separation of enantiomers with excellent repeatability and reproducibility. The proposed strategy provides a promising platform for the synthesis of chiral COFs and their chiral separation application.

  11. Bottom-up synthesis of chiral covalent organic frameworks and their bound capillaries for chiral separation.

    PubMed

    Qian, Hai-Long; Yang, Cheng-Xiong; Yan, Xiu-Ping

    2016-07-12

    Covalent organic frameworks (COFs) are a novel class of porous materials, and offer great potential for various applications. However, the applications of COFs in chiral separation and chiral catalysis are largely underexplored due to the very limited chiral COFs available and their challenging synthesis. Here we show a bottom-up strategy to construct chiral COFs and an in situ growth approach to fabricate chiral COF-bound capillary columns for chiral gas chromatography. We incorporate the chiral centres into one of the organic ligands for the synthesis of the chiral COFs. We subsequently in situ prepare the COF-bound capillary columns. The prepared chiral COFs and their bound capillary columns give high resolution for the separation of enantiomers with excellent repeatability and reproducibility. The proposed strategy provides a promising platform for the synthesis of chiral COFs and their chiral separation application.

  12. Correlation between structures of chiral polymers and their efficiency for chiral resolution by crystallization.

    PubMed

    Menahem, Tali; Pravda, Martin; Mastai, Yitzhak

    2009-10-01

    In this work, we describe the correlation between chiral polymer structures, particularly alpha-helical and random coil conformations, and their efficiency as chiral resolving agents in crystallization processes. A set of chiral block copolymers based on polyethylene oxide with chiral glutamic acid oligopeptide segments (PEG(113)-b-(+)-(S)-Glu(20)) were synthesized and employed as additives in the crystallization of rac-threonine. CD spectroscopy demonstrates that structures of chiral polymers could be switched between a helical and a disordered random coil by pH. The effect of these polymers at different conformations on the crystallization kinetics, crystal morphology, and chiral resolution of rac-threonine is reported. Our study demonstrates that only chiral polymers with alpha-helical conformations of the chiral segment are effective as additives for chiral resolution throughout crystallization. Overall, our results provide useful guidelines for the selection and design of chiral polymer additives that will act efficiently for chiral resolution by crystallization. PMID:19455618

  13. Development of a chiral stationary phase based on cinchonidine. Comparison with a quinine-based chiral column.

    PubMed

    Keunchkarian, Sonia; Grisales, Jaiver Osorio; Padró, Juan M; Boeris, Susana; Castells, Cecilia B

    2012-07-01

    A chiral anion-exchanger stationary phase based on cinchonidine (CD) was developed. Two columns were packed with and without endcapping (EC) treatment (CD-chiral stationary phase[CD-CSP(EC)] and [CD-CSP], respectively) and studied for their ability to separate N-2,4-dinitrophenyl α-amino acids (DNP-amino acids) enantiomers over a temperature range of 10-40 °C with a hydro-organic buffer mobile phase. The more hydrophobic, endcapped stationary phase showed significantly larger retentive capacity than the non-endcapped one. The apparent thermodynamic transfer parameters of the enantiomers from the mobile to both CSPs were estimated from van't Hoff plots within the cited temperature range. Similar studies with two natural quinine-based columns (QN-CSP and QN-CSP(EC)) were previously reported. In this work, a critical comparison in the chiral recognition ability to DNP-amino acids of these cinchonidine and QN-based chiral columns was drawn. It has been found that QN-based CSPs show greater chiral recognition capability towards these derivatives than CD-CSPs. The influence of the QN methoxy group on the equilibrium constants of the enantioselective interaction between these DNP-amino acids with these two cinchona CSPs could be assessed.

  14. Imaging chiral symmetry breaking from Kekulé bond order in graphene

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Christopher; Kim, Cheol-Joo; Brown, Lola; Schiros, Theanne; Nordlund, Dennis; Lochocki, Edward B.; Shen, Kyle M.; Park, Jiwoong; Pasupathy, Abhay N.

    2016-10-01

    Chirality--or `handedness’--is a symmetry property crucial to fields as diverse as biology, chemistry and high-energy physics. In graphene, chiral symmetry emerges naturally as a consequence of the carbon honeycomb lattice. This symmetry can be broken by interactions that couple electrons with opposite momenta in graphene. Here we directly visualize the formation of Kekulé bond order, one such phase of broken chiral symmetry, in an ultraflat graphene sheet grown epitaxially on a copper substrate. We show that its origin lies in the interactions between individual vacancies in the copper substrate that are mediated electronically by the graphene. We show that this interaction causes the bonds in graphene to distort, creating a phase with broken chiral symmetry. The Kekulé ordering is robust at ambient temperature and atmospheric conditions, indicating that intercalated atoms may be harnessed to drive graphene and other two-dimensional materials towards electronically desirable and exotic collective phases.

  15. Synthesis of novel glucose-based polymers and their applications as chiral stationary phases for high performance liquid chromatography.

    PubMed

    Ikai, Tomoyuki; Yamada, Takayuki

    2016-01-01

    Two novel polymers containing glucose units as the main-chain that only differ in terms of their regioregularity were synthesized to evaluate their chiral recognition abilities as chiral stationary phases (CSPs) for high performance liquid chromatography (HPLC). The regioregular polymer (poly-5) shows clear resolution ability for the racemate of cobalt (III) acetylacetonate (Co(acac)3), whereas the corresponding regioirregular polymer (poly-3) does not show any chiral recognition for Co (acac)3. The regioregular polymer main-chain seems to play an important role not only in providing an efficient interaction with the racemate but also in expressing the chiral recognition ability as a CSP for HPLC. PMID:27319157

  16. Optical properties of chiral three-dimensional plasmonic oligomers at the onset of charge-transfer plasmons.

    PubMed

    Hentschel, Mario; Wu, Lin; Schäferling, Martin; Bai, Ping; Li, Er Ping; Giessen, Harald

    2012-11-27

    We demonstrate strong chiral optical response in three-dimensional chiral nanoparticle oligomers in the wavelength regime between 700 and 3500 nm. We show in experiment and simulation that this broad-band response occurs at the onset of charge transfer between the individual nanoparticles. The ohmic contact causes a strong red shift of the fundamental mode, while the geometrical shape of the resulting fused particles still allows for an efficient excitation of higher order modes. Calculated spectra and field distributions confirm our interpretation and show a number of interacting plasmonic modes. Our results deepen the understanding of the chiral optical response in complex chiral plasmonic nanostructures and pave the road toward broad-band chiral optical devices with strong responses, for example, for chiral plasmon rulers or sensing applications. PMID:23078518

  17. Quantum phase transitions of spin chiral nanotubes

    NASA Astrophysics Data System (ADS)

    Matsumoto, Munehisa; Sakai, Toru; Sato, Masahiro; Takayama, Hajime; Todo, Synge

    2005-11-01

    Recently many interesting magnetic nanostructures have been fabricated and much attention is arising on the rich magnetic properties that originate in the quantum effects eminent in the nanoscale world. One of the peculiar aspects of the quantum effects is the spin excitation gap. In the spin- 1/2 low-dimensional systems, the spin gap often appears when the lattice dimerization or the frustration in the spin-spin interaction are introduced. In the present study, we investigate the ground-state property of the spin- 1/2 antiferromagnetic spin chiral nanotubes with the spatial modulation in the spin-spin interaction. The ground-state phase diagrams of them are determined by observing the behavior of the expectation value of the Lieb-Schultz-Mattis slow-twist operator calculated by the quantum Monte Carlo method with the continuous-time loop algorithm. We discuss the relation between the characteristic of the topology of the phase diagram and the chiral vector of the nanotubes.

  18. Chiral magnetic order at surfaces driven by inversion asymmetry.

    PubMed

    Bode, M; Heide, M; von Bergmann, K; Ferriani, P; Heinze, S; Bihlmayer, G; Kubetzka, A; Pietzsch, O; Blügel, S; Wiesendanger, R

    2007-05-10

    Chirality is a fascinating phenomenon that can manifest itself in subtle ways, for example in biochemistry (in the observed single-handedness of biomolecules) and in particle physics (in the charge-parity violation of electroweak interactions). In condensed matter, magnetic materials can also display single-handed, or homochiral, spin structures. This may be caused by the Dzyaloshinskii-Moriya interaction, which arises from spin-orbit scattering of electrons in an inversion-asymmetric crystal field. This effect is typically irrelevant in bulk metals as their crystals are inversion symmetric. However, low-dimensional systems lack structural inversion symmetry, so that homochiral spin structures may occur. Here we report the observation of magnetic order of a specific chirality in a single atomic layer of manganese on a tungsten (110) substrate. Spin-polarized scanning tunnelling microscopy reveals that adjacent spins are not perfectly antiferromagnetic but slightly canted, resulting in a spin spiral structure with a period of about 12 nm. We show by quantitative theory that this chiral order is caused by the Dzyaloshinskii-Moriya interaction and leads to a left-rotating spin cycloid. Our findings confirm the significance of this interaction for magnets in reduced dimensions. Chirality in nanoscale magnets may play a crucial role in spintronic devices, where the spin rather than the charge of an electron is used for data transmission and manipulation. For instance, a spin-polarized current flowing through chiral magnetic structures will exert a spin-torque on the magnetic structure, causing a variety of excitations or manipulations of the magnetization and giving rise to microwave emission, magnetization switching, or magnetic motors.

  19. In situ synthesis of di-n-butyl l-tartrate-boric acid complex chiral selector and its application in chiral microemulsion electrokinetic chromatography.

    PubMed

    Hu, Shaoqiang; Chen, Yonglei; Zhu, Huadong; Zhu, Jinhua; Yan, Na; Chen, Xingguo

    2009-11-01

    A novel procedure for in situ assembling a complex chiral selector, di-n-butyl l-tartrate-boric acid complex, by the reaction of di-n-butyl l-tartrate with boric acid in a running buffer was reported and its application in the enantioseparation of beta-blockers and structural related compounds by chiral microemulsion electrokinetic chromatography (MEEKC) has been demonstrated. In order to achieve a good enantioseparation, the effect of dibutyl l-tartrate and sodium tetraborate concentration, surfactant identity and concentration, cosurfactant, buffer pH and composition, organic modifiers, as well as applied voltage and capillary length were investigated. Ten pairs of enantiomers that could not be separated with only dibutyl l-tartrate, obtained good chiral separation using the complex chiral selector; among them, seven pairs could be baseline resolved under optimized experimental conditions. The fixation of chiral centers by the formation of five-membered rings, and being oppositely charged with basic analytes were thought to be the key factors giving the complex chiral selector a superior chiral recognition capability. The effect of the molecular structure of analytes on enantioseparation was discussed in terms of molecular interaction.

  20. The effective chiral Lagrangian from the theta term

    SciTech Connect

    Mereghetti, E.; Hockings, W.H.; Kolck, U. van

    2010-11-15

    We construct the effective chiral Lagrangian involving hadronic and electromagnetic interactions originating from the QCD {theta}-bar term. We impose vacuum alignment at both quark and hadronic levels, including field redefinitions to eliminate pion tadpoles. We show that leading time-reversal-violating (TV) hadronic interactions are related to isospin-violating interactions that can in principle be determined from charge-symmetry-breaking experiments. We discuss the complications that arise from TV electromagnetic interactions. Some implications of the expected sizes of various pion-nucleon TV interactions are presented, and the pion-nucleon form factor is used as an example.

  1. Can a Non-Chiral Object Be Made of Two Identical Chiral Moieties?

    ERIC Educational Resources Information Center

    LeMarechal, Jean Francois

    2008-01-01

    Several pedagogical objects can be used to discuss chirality. Here, we use the cut of an apple to show that the association of identical chiral moieties can form a non-chiral object. Octahedral chirality is used to find situations equivalent to the cut of the apple. (Contains 5 figures.)

  2. Strange Disoriented Chiral Condensates

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Mohamed; Gavin, Sean

    2002-10-01

    Enhancement of omega and anti-omega baryon production in Pb+Pb collisions at the CERN SPS can be explained by the formation of many small regions of disordered chiral condensate. This explanation implies that neutral and charged kaons as well as pions must exhibit novel isospin fluctuations. Fluctuations due to transient behavior of the Polyakov Loop condensate can produce similar phenomena. Kapusta and Gavin have computed the distribution of the fraction of neutral pions and kaons from such regions. We proposed robust statistical observables that can be used to extract the novel isospin fluctuations from background contributions in neutral/charged pion and K-short/K-charged correlation measurements at RHIC and LHC. The STAR experiment is currently examining K-short/K-charged correlations. Note that Pruneau, Voloshin and Gavin have proposed similar observables to study net-charge fluctuations. To obtain a baseline for comparison to RHIC and SPS experiments, Abdel-Aziz and Gavin compute these observables using numerical simulations using HIJING and URQMD event generators. We also obtain limits on the size and number of disordered regions by comparing to photon and charged-pion searches from WA98 and other SPS experiments. We will compare to the first results from STAR K-short/K-charged analysis.

  3. Phase diagram of chirally imbalanced QCD matter

    SciTech Connect

    Chernodub, M. N.; Nedelin, A. S.

    2011-05-15

    We compute the QCD phase diagram in the plane of the chiral chemical potential and temperature using the linear sigma model coupled to quarks and to the Polyakov loop. The chiral chemical potential accounts for effects of imbalanced chirality due to QCD sphaleron transitions which may emerge in heavy-ion collisions. We found three effects caused by the chiral chemical potential: the imbalanced chirality (i) tightens the link between deconfinement and chiral phase transitions; (ii) lowers the common critical temperature; (iii) strengthens the order of the phase transition by converting the crossover into the strong first order phase transition passing via the second order end point. Since the fermionic determinant with the chiral chemical potential has no sign problem, the chirally imbalanced QCD matter can be studied in numerical lattice simulations.

  4. Chiral Chlordane Components in Environmental Matrices

    EPA Science Inventory

    Chlordane, a persistent, bioaccumulative and toxic organochlorine pesticide, has been studied for many years. Since the advent of chiral analysis for environmental samples, over 2,400 measurements have been made of various chiral chlordane components. Chlordane enantiomer fractio...

  5. Tactoids of chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Palacio-Betancur, Viviana; Villada-Gil, Stiven; Zhou, Ye; Armas-Pérez, Julio C.; de Pablo, Juan José; Hernández-Ortiz, Juan Pablo

    The phase diagram of chiral liquid crystals confined in ellipsoids is obtained, by following a theoretically informed Monte Carlo relaxation of the tensor alignment field Q. The free energy of the system is described by a functional in the framework of the Landau-de Gennes formalism. This study also includes the effect of anchoring strength, curvature, and chirality of the system. In the low chirality region of the phase diagram we found the twist bipolar (BS) phase and some cholesteric phases such as the radial spherical structure (RSS), twist cylinder (TC) and double twist cylinder (DTC) whose axis of rotation is not necessarily aligned with the major axis of the geometry. For high chirality scenarios, the disclination lines are twisted or bent near the surface preventing the formation of symmetric networks of defects, although an hexagonal pattern is formed on the surface which might serve as open sites for collocation of colloids. By analyzing the free energies of isochoric systems, prolate geometries tend to be more favorable for high chirality and low anchoring conditions. Universidad Nacional de Colombia Ph.D. grant and COLCIENCIAS under the Contract No. 110-165-843-748. CONACYT for Postdoctoral Fellowships Nos. 186166 and 203840.

  6. Controlling Chirality of Entropic Crystals

    NASA Astrophysics Data System (ADS)

    Damasceno, Pablo; Karas, Andrew; Schultz, Benjamin; Engel, Michael; Glotzer, Sharon

    Colloidal crystal structures with complexity and diversity rivaling atomic and molecular crystals have been predicted and obtained for hard particles by entropy maximization. However, thus far homochiral colloidal crystals, which are candidates for photonic metamaterials, are absent. Using Monte Carlo simulations we show that chiral polyhedra exhibiting weak directional entropic forces self-assemble either an achiral crystal or a chiral crystal with limited control over the crystal handedness. Building blocks with stronger faceting exhibit higher selectivity and assemble a chiral crystal with handedness uniquely determined by the particle chirality. Tuning the strength of directional entropic forces by means of particle rounding or the use of depletants allows for reconfiguration between achiral and homochiral crystals. We rationalize our findings by quantifying the chirality strength of each particle, both from particle geometry and potential of mean force and torque diagrams. Work supported by the National Science Foundation, Division of Materials Research Award No. DMR 1120923, U.S. Army Research Office under Grant Award No. W911NF-10-1-0518, and also by the DOD/ASD (R&E) under Award No. N00244-09-1-0062.

  7. Nanospheres, nanotubes, toroids, and gels with controlled macroscopic chirality.

    PubMed

    Arias, Sandra; Freire, Félix; Quiñoá, Emilio; Riguera, Ricardo

    2014-12-01

    The interaction of a highly dynamic poly(aryl acetylene) (poly-1) with Li(+), Na(+), and Ag(+) leads to macroscopically chiral supramolecular nanospheres, nanotubes, toroids, and gels. With Ag(+), nanospheres with M helicity and tunable sizes are generated, which complement those obtained from the same polymer with divalent cations. With Li(+) or Na(+), poly-1 yields chiral nanotubes, gels, or toroids with encapsulating properties and M helicity. Right-handed supramolecular structures can be obtained by using the enantiomeric polymer. The interaction of poly-1 with Na(+) produces nanostructures whose helicity is highly dependent on the solvation state of the cation. Therefore, structures with either of the two helicities can be prepared from the same polymer by manipulation of the cosolvent. Such chiral nanotubes, toroids, and gels have previously not been obtained from helical polymer-metal complexes. Chiral nanospheres made of poly(aryl acetylene) that were previously assembled with metal(II) species can now be obtained with metal(I) species. PMID:25209219

  8. Chirality: a relational geometric-physical property.

    PubMed

    Gerlach, Hans

    2013-11-01

    The definition of the term chirality by Lord Kelvin in 1893 and 1904 is analyzed by taking crystallography at that time into account. This shows clearly that chirality is a relational geometric-physical property, i.e., two relations between isometric objects are possible: homochiral or heterochiral. In scientific articles the relational term chirality is often mistaken for the two valued measure for the individual (absolute) sense of chirality, an arbitrary attributive term.

  9. Chiral lattice fermions with correct vacuum polarization and chiral anomaly

    SciTech Connect

    Pryor, C. )

    1991-04-15

    An action for chiral lattice fermions is proposed, which avoids the Nielsen-Ninomiya theorem by virtue of its nonlocality and nonbilinearity. The action is constructed by eliminating the extra fermion modes with a gauge-violating Majorana-type Wilson mass, which is then rendered invariant by an integration over gauge transformations. The free propagator is calculated, and the one-loop vacuum polarization is shown to be identical to that for Wilson fermions, even at nonzero lattice spacing. Also the chiral anomaly is shown to be the same as for Wilson fermions in the continuum limit.

  10. Electrical Property Analytical Prediction on Archimedes Chiral Carbon Nanoscrolls

    NASA Astrophysics Data System (ADS)

    Hassanzadazar, M.; Ahmadi, M. T.; Ismail, Razali; Goudarzi, Hadi

    2016-10-01

    Carbon nanoscrolls (CNS) with flexible exterior areas and interesting electrical and mechanical properties have gained interest in recent years, both experimentally and theoretically. These structures have been employed as ion channels, tunable water channels, molecular sensors, and gene and drug distribution systems. In this study, electrical behaviour of all types of CNS containing armchair, zigzag, and chiral CNSs band structure is investigated. In armchair CNSs, the small band gap among valence and the conduction band as a pseudo-gap are reported, which reveals a semimetallic property for some of these CNSs. This small band gap, as a result of layer interaction, has been confirmed. Also, in many other types of armchair CNSs at the Fermi level, related levels cross each other, illustrating metallic characteristics. On the other hand, our numerical results show small band gaps for zigzag types of CNSs, which means that they are semiconductors. However, it cannot be considered as a general occurrence because only in rare circumstances is a very small band gap observed that gives rise to semimetallic CNSs. In addition, the electrical properties of chiral CNSs are explored. Small band gaps between the associated valence and the conduction band reveals that chiral CNSs mainly exhibit semiconducting behaviour. Finally, all the numerical results are tabulated in the form of a CNS periodic table and a symmetric arrangement with respect to the armchair nanoscrolls and as a table diagonal data for the chiral CNSs is noticed. In addition, this investigation highlights the variations of the energy structure of chiral CNSs with respect to their length. Presented results offer significant potential for chiral CNSs as an alternative to silicon-based sensors in nanotechnology. Therefore, the band gap variations in the presence of attached materials as a sensor platform need to be explored.

  11. Electrical Property Analytical Prediction on Archimedes Chiral Carbon Nanoscrolls

    NASA Astrophysics Data System (ADS)

    Hassanzadazar, M.; Ahmadi, M. T.; Ismail, Razali; Goudarzi, Hadi

    2016-06-01

    Carbon nanoscrolls (CNS) with flexible exterior areas and interesting electrical and mechanical properties have gained interest in recent years, both experimentally and theoretically. These structures have been employed as ion channels, tunable water channels, molecular sensors, and gene and drug distribution systems. In this study, electrical behaviour of all types of CNS containing armchair, zigzag, and chiral CNSs band structure is investigated. In armchair CNSs, the small band gap among valence and the conduction band as a pseudo-gap are reported, which reveals a semimetallic property for some of these CNSs. This small band gap, as a result of layer interaction, has been confirmed. Also, in many other types of armchair CNSs at the Fermi level, related levels cross each other, illustrating metallic characteristics. On the other hand, our numerical results show small band gaps for zigzag types of CNSs, which means that they are semiconductors. However, it cannot be considered as a general occurrence because only in rare circumstances is a very small band gap observed that gives rise to semimetallic CNSs. In addition, the electrical properties of chiral CNSs are explored. Small band gaps between the associated valence and the conduction band reveals that chiral CNSs mainly exhibit semiconducting behaviour. Finally, all the numerical results are tabulated in the form of a CNS periodic table and a symmetric arrangement with respect to the armchair nanoscrolls and as a table diagonal data for the chiral CNSs is noticed. In addition, this investigation highlights the variations of the energy structure of chiral CNSs with respect to their length. Presented results offer significant potential for chiral CNSs as an alternative to silicon-based sensors in nanotechnology. Therefore, the band gap variations in the presence of attached materials as a sensor platform need to be explored.

  12. Density-Dependent Properties of Hadronic Matter in the self-consistent Chiral ({sigma},{pi},{omega}) Mean-Field Model

    SciTech Connect

    Uechi, Schun T.; Uechi, Hiroshi

    2011-05-06

    Density-dependent relations among saturation properties of symmetric nuclear matter and properties of hadronic stars are discussed by applying the conserving chiral nonlinear ({sigma},{pi},{omega}) hadronic mean-field theory. The chiral nonlinear ({sigma},{pi},{omega}) mean-field theory is an extension of the conserving nonlinear (nonchiral) {sigma}-{omega} hadronic mean-field theory which is thermodynamically consistent, relativistic and is a Lorentz-covariant mean-field theory of hadrons. In the extended chiral ({sigma},{pi},{omega}) mean-field model, all the masses of hadrons are produced by the breaking of chiral symmetry, which is different from other conventional chiral partner models. By comparing both nonchiral and chiral mean-field approximations, the effects of the chiral symmetry breaking mechanism on the mass of {sigma}-meson, coefficients of nonlinear interactions and Fermi-liquid properties are investigated in nuclear matter and neutron stars.

  13. Magnetic vortex chirality determination via local hysteresis loops measurements with magnetic force microscopy

    PubMed Central

    Coïsson, Marco; Barrera, Gabriele; Celegato, Federica; Manzin, Alessandra; Vinai, Franco; Tiberto, Paola

    2016-01-01

    Magnetic vortex chirality in patterned square dots has been investigated by means of a field-dependent magnetic force microscopy technique that allows to measure local hysteresis loops. The chirality affects the two loop branches independently, giving rise to curves that have different shapes and symmetries as a function of the details of the magnetisation reversal process in the square dot, that is studied both experimentally and through micromagnetic simulations. The tip-sample interaction is taken into account numerically, and exploited experimentally, to influence the side of the square where nucleation of the vortex preferably occurs, therefore providing a way to both measure and drive chirality with the present technique. PMID:27426442

  14. Spherical β-cyclodextrin-silica hybrid materials for multifunctional chiral stationary phases.

    PubMed

    Wang, Litao; Dong, Shuqing; Han, Feng; Zhao, Yingwei; Zhang, Xia; Zhang, Xiaoli; Qiu, Hongdeng; Zhao, Liang

    2015-02-27

    Spherical β-CD-silica hybrid materials have been prepared successfully by simple one-pot polymerization, which provide a new strategy to construct new type of HPLC chiral stationary phases. Various β-CD, ethane, triazinyl and 3,5-dimethylphenyl functional groups that can provide multiple interactions were introduced into the pore channels and pore wall framework of mesoporous materials, respectively. The materials towards some chiral, acidic, anilines and phenols compounds showed multiple chromatographic separation functions including racemic resolution, anion exchange and achiral separations with a typical feature of normal/reversed phase chromatography. Multi-tasking including racemic resolution and achiral separations for selected compounds were performed simultaneously on a chiral chromatographic column. The multifunctional character of materials arises from the multiple interactions including hydrophobic interaction, π-π interaction, anion exchange, inclusion interaction and hydrogen bonding interaction. PMID:25637012

  15. Chiral cardiovascular drugs: an overview.

    PubMed

    Ranade, Vasant V; Somberg, John C

    2005-01-01

    Stereochemistry in drug molecules is rapidly becoming an important aspect in drug research, design, and development. Recently, individual stereoisomers of drug molecules with asymmetric centers such as fexofenadine, cetirizine, verapamil, fluoxetine, levalbutarol, and amphetamine, for example, have been separated and developed as individual drugs. These stereoisomers have different therapeutic activity, and each isomer has contributed differently with respect to its formulation's pharmacologic activity, side effects, and toxicity. The present overview discusses chirality among a select group of cardiovascular drugs, their stereochemical synthesis/preparation, isolation techniques using chiral chromatography, methods for confirmation of their enantiomeric purity, pharmacodynamics, and pharmacokinetics. Chirality has been visualized as an important factor in cardiovascular research. It is also becoming evident in other areas of therapeutics.

  16. Polymorphism in supramolecular chiral structures of R- and S-alanine on Cu(1 1 0)

    NASA Astrophysics Data System (ADS)

    Barlow, S. M.; Louafi, S.; Le Roux, D.; Williams, J.; Muryn, C.; Haq, S.; Raval, R.

    2005-10-01

    A comprehensive study of the local and supramolecular adsorption structures created by the chiral R- and S-enantiomers of alanine on the Cu(1 1 0) surface has been conducted using a multi-technique approach, including reflection absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM). Over the entire 300-470 K temperature range studied, the amino acid is found to adsorb as an alaninate species with a local chiral adsorption motif. However, this singular preference of local chemical form contrasts sharply with the supramolecular organisation at the surface where polymorphism is exhibited. This polymorphic behaviour arises from subtle and dynamic changes in the bonding, orientation and adsorption footprints of individual molecules, leading to alterations in the molecule-metal, intermolecular and metal-metal interactions that dictate self-assembly. Thus, at low coverage, a single disordered phase is observed but at higher coverage, three other temperature dependent phases occur. At room temperature, a two-dimensional equivalent of a 'nematic' phase is constructed from short single- and double-chain chiral assemblies that possess a preferred chiral orientation but no long range periodicity. This 'nematic' phase acts as a precursor to a highly ordered chiral supramolecular assembly, created at 430 K, that consists of regular arrays of size- and shape-defined chiral clusters. This phase possesses global organisational chirality with only one chiral domain observed for each enantiomer. For both the 'nematic' and the highly ordered chiral phase, the organisation for the R-enantiomer is the mirror image of that seen for the S-enantiomer, i.e., there is chirality transfer from the nanoscale to the macroscale. By 470 K, both R- and S-alanine form an achirally organised (3 × 2) structure that appears to be the thermodynamically favoured phase for the alanine/Cu(1 1 0

  17. Zwitterionic chiral stationary phases based on cinchona and chiral sulfonic acids for the direct stereoselective separation of amino acids and other amphoteric compounds.

    PubMed

    Zhang, Tong; Holder, Emilie; Franco, Pilar; Lindner, Wolfgang

    2014-06-01

    An extensive series of free amino acids and analogs were directly resolved into enantiomers (and stereoisomers where appropriate) by HPLC on zwitterionic chiral stationary phases (Chiralpak ZWIX(+) and Chiralpak ZWIX(-)). The interaction and chiral recognition mechanisms were based on the synergistic double ion-paring process between the analyte and the chiral selectors. The chiral separation and elution order were found to be predictable for primary α-amino acids with apolar aliphatic side chains. A systematic investigation was undertaken to gain an insight into the influence of the structural features on the enantiorecognition. The presence of polar and/or aromatic groups in the analyte structure is believed to tune the double ion-paring equilibrium by the involvement of the secondary interaction forces such as hydrogen bonding, Van der Waals forces and π-π stacking in concert with steric parameters. The ZWIX chiral columns were able to separate enantiomers and stereoisomers of various amphoteric compounds with no need for precolumn derivatization. Column switching between ZWIX(+) and ZWIX(-) is believed to be an instrumental tool to reverse or control the enantiomers elution order, due to the complementarity of the applied chiral selectors.

  18. Chiral selectivity of amino acid adsorption on chiral surfaces—The case of alanine on Pt

    SciTech Connect

    Franke, J.-H.; Kosov, D. S.

    2015-02-07

    We study the binding pattern of the amino acid alanine on the naturally chiral Pt surfaces Pt(531), Pt(321), and Pt(643). These surfaces are all vicinal to the (111) direction but have different local environments of their kink sites and are thus a model for realistic roughened Pt surfaces. Alanine has only a single methyl group attached to its chiral center, which makes the number of possible binding conformations computationally tractable. Additionally, only the amine and carboxyl group are expected to interact strongly with the Pt substrate. On Pt(531), we study the molecule in its pristine as well as its deprotonated form and find that the deprotonated one is more stable by 0.47 eV. Therefore, we study the molecule in its deprotonated form on Pt(321) and Pt(643). As expected, the oxygen and nitrogen atoms of the deprotonated molecule provide a local binding “tripod” and the most stable adsorption configurations optimize the interaction of this “tripod” with undercoordinated surface atoms. However, the interaction of the methyl group plays an important role: it induces significant chiral selectivity of about 60 meV on all surfaces. Hereby, the L-enantiomer adsorbs preferentially to the Pt(321){sup S} and Pt(643){sup S} surfaces, while the D-enantiomer is more stable on Pt(531){sup S}. The binding energies increase with increasing surface density of kink sites, i.e., they are largest for Pt(531){sup S} and smallest for Pt(643){sup S}.

  19. Surfaces and chirality in liquid crystals

    NASA Astrophysics Data System (ADS)

    Kang, Daeseung

    1999-10-01

    The effects of surfaces and chirality in liquid crystals were studied in this thesis. Four different experiments were presented to investigate the different aspects of their role in liquid crystal physics. A liquid crystal cell treated for homeotropic alignment with different surfactants at the two surfaces was subjected to an electric field E in the plane of the cell. The longitudinal polarization at the surface couples with the external field, and in consequence exerts a torque on molecules. The differential optical retardation deltaalpha due to a slight deformation was found to be linear in field over a frequency range 10 < o < 105 Hz, where d(deltaalpha)/dE is proportional to o -1. As a different aspect of the surface, the phenomenon of a chiral liquid crystal in highly restricted geometry was also investigated, where the random surface dominates the bulk. The optical rotatory power of the chiral liquid crystal in the porous medium was drastically altered from that of the bulk liquid crystal. The observed behavior may be attributed to a combination of surface interactions and finite size effects, which are discussed in terms of an infrared cutoff in the orientational pair correlation function. Chirality manifests itself not only as an optical activity in nematics, but more strikingly in forms of ferroelectric and antiferroelectric phases in smectics. The anticlinic interlayer coupling coefficient U between smectic layers was evaluated for a pitch-compensated antiferroelectric liquid crystal by optical observation of the optic mode response to an in-plane electric field. The result is in good agreement with Us estimated from the threshold field for the onset of solitary waves, and provides a strong support for the switching model based on the free energy. Finally, a new trimer liquid crystal based on a terminal-lateral-lateral-terminal connection was investigated. Magnetically induced Freedericksz measurements were performed to extract the elastic constants of

  20. Collisions in Chiral Kinetic Theory.

    PubMed

    Chen, Jing-Yuan; Son, Dam T; Stephanov, Mikhail A

    2015-07-10

    Using a covariant formalism, we construct a chiral kinetic theory Lorentz invariant to order O(ℏ), which includes collisions. We find a new contribution to the particle number current due to the side jumps required by the conservation of angular momentum during collisions. We also find a conserved symmetric stress-energy tensor as well as the H function obeying Boltzmann's H theorem. We demonstrate their use by finding a general equilibrium solution and the values of the anomalous transport coefficients characterizing the chiral vortical effect.

  1. Chiral symmetry on the lattice

    SciTech Connect

    Creutz, M.

    1994-11-01

    The author reviews some of the difficulties associated with chiral symmetry in the context of a lattice regulator. The author discusses the structure of Wilson Fermions when the hopping parameter is in the vicinity of its critical value. Here one flavor contrasts sharply with the case of more, where a residual chiral symmetry survives anomalies. The author briefly discusses the surface mode approach, the use of mirror Fermions to cancel anomalies, and finally speculates on the problems with lattice versions of the standard model.

  2. Optical activity of chirally distorted nanocrystals

    NASA Astrophysics Data System (ADS)

    Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-05-01

    We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

  3. Quark matter and meson properties in a Nonlocal SU(3) chiral quark model at finite temperature

    SciTech Connect

    Gomez Dumm, D.; Contrera, G. A.

    2012-06-15

    We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with a background color field. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles, and decay constants.

  4. Coriolis effect and spin Hall effect of light in an inhomogeneous chiral medium.

    PubMed

    Zhang, Yongliang; Shi, Lina; Xie, Changqing

    2016-07-01

    We theoretically investigate the spin Hall effect of spinning light in an inhomogeneous chiral medium. The Hamiltonian equations of the photon are analytically obtained within eikonal approximation in the noninertial orthogonal frame. Besides the usual spin curvature coupling, the chiral parameter enters the Hamiltonian as a spin-torsion-like interaction. We reveal that both terms have parallel geometric origins as the Coriolis terms of Maxwell's equations in nontrivial frames.

  5. Chiral xenobiotics bioaccumulations and environmental health prospectives.

    PubMed

    Hussain, Iqbal; ALOthman, Zeid A; Alwarthan, Abdulrahman A; Sanagi, Mohd Marsin; Ali, Imran

    2015-08-01

    The chiral xenobiotics are very dangerous for all of us due to the different enantioselective toxicities of the enantiomers. Besides, these have different enantioselective bioaccumulations and behaviors in our body and other organisms. It is of urgent need to understand the enantioselective bioaccumulations, toxicities, and the health hazards of the chiral xenobiotics. The present article describes the classification, sources of contamination, distribution, enantioselective bioaccumulation, and the toxicities of the chiral xenobiotics. Besides, the efforts are also made to discuss the prevention and remedial measures of the havoc of the chiral xenobiotics. The challenges of the chiral xenobiotics have also been highlighted. Finally, future prospectives are also discussed.

  6. Chirality effect in disordered graphene ribbon junctions

    NASA Astrophysics Data System (ADS)

    Long, Wen

    2012-05-01

    We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon.

  7. Micropatterning of cells reveals chiral morphogenesis

    PubMed Central

    2013-01-01

    Invariant left-right (LR) patterning or chirality is critical for embryonic development. The loss or reversal of LR asymmetry is often associated with malformations and disease. Although several theories have been proposed, the exact mechanism of the initiation of the LR symmetry has not yet been fully elucidated. Recently, chirality has been detected within single cells as well as multicellular structures using several in vitro approaches. These studies demonstrated the universality of cell chirality, its dependence on cell phenotype, and the role of physical boundaries. In this review, we discuss the theories for developmental LR asymmetry, compare various in vitro cell chirality model systems, and highlight possible roles of cell chirality in stem cell differentiation. We emphasize that the in vitro cell chirality systems have great promise for helping unveil the nature of chiral morphogenesis in development. PMID:23672821

  8. Basics of Resonance Chiral Theory

    SciTech Connect

    Portoles, J.

    2010-12-28

    We review the main components that have to be considered, within Resonance Chiral Theory, in the study of processes whose dynamics is dominated by hadron resonances. We show its application in the study of the {tau}{yields}{pi}{pi}{pi}{nu}{sub {tau}} decay.

  9. Chiral asymmetry in spiral galaxies?

    PubMed

    Kondepudi, D K; Durand, D J

    2001-07-01

    Spiral galaxies are chiral entities when coupled with the direction of their recession velocity. As viewed from the Earth, the S-shaped and Z-shaped spiral galaxies are two chiral forms. What is the nature of chiral symmetry in spiral galaxies? In the Carnegie Atlas of Galaxies that lists photographs of a total of 1,168 galaxies, we found 540 galaxies, classified as normal or barred spirals, that are clearly identifiable as S- or Z- type. The recession velocities for 538 of these galaxies could be obtained from this atlas and other sources. A statistical analysis of this sample reveals no overall asymmetry but there is a significant asymmetry in certain subclasses: dominance of S-type galaxies in the Sb class of normal spiral galaxies and a dominance of Z-type in the SBb class of barred spiral galaxies. Both S- and Z-type galaxies seem to have similar velocity distribution, indicating no spatial segregation of the two chiral forms.

  10. Baryon and chiral symmetry breaking

    SciTech Connect

    Gorsky, A.; Krikun, A.

    2014-07-23

    We briefly review the generalized Skyrmion model for the baryon recently suggested by us. It takes into account the tower of vector and axial mesons as well as the chiral symmetry breaking. The generalized Skyrmion model provides the qualitative explanation of the Ioffe’s formula for the baryon mass.

  11. Intrinsic transverse momentum and dynamical chiral symmetry breaking

    SciTech Connect

    Christian Weiss, Peter Schweitzer, Mark Strikman

    2013-01-01

    We study the effect of QCD vacuum structure on the intrinsic transverse momentum distribution of partons in the nucleon at a low scale. The dynamical breaking of chiral symmetry is caused by non-perturbative interactions at distances of the order rho ~ 0.2 - 0.3 fm, much smaller than the typical nucleon size R ~ 1 fm, resulting in a two-scale picture of nucleon structure. Using an effective dynamical model based on chiral constituent quark degrees of freedom and the 1/N_c expansion (chiral quark-soliton model), we calculate the transverse momentum distribution of quarks and antiquarks at a low scale. The distribution of valence quarks is localized at p_T ~ 1/R. The distribution of flavor-singlet unpolarized sea quarks exhibits a power-like tail extending up to the chiral-symmetry-breaking scale 1/{rho}. A similar tail is present in the flavor-nonsinglet polarized sea. These features are model-independent and represent the imprint of the QCD vacuum on the nucleon's partonic structure. At the level of the nucleon's light-cone wave function, we show that sea quarks partly exist in correlated pairs of transverse size {rho} << R, analogous to short-range NN correlations in nuclei. We discuss the implications of our findings for the transverse momentum distributions in hard scattering processes (semi-inclusive DIS, Drell-Yan pair production) and possible experimental tests of the non-perturbative parton correlations induced by QCD vacuum structure.

  12. Construction of Electrochemical Chiral Interfaces with Integrated Polysaccharides via Amidation.

    PubMed

    Bao, Liping; Chen, Xiaohui; Yang, Baozhu; Tao, Yongxin; Kong, Yong

    2016-08-24

    Polysaccharides of sodium carboxymethyl cellulose (CMC) and chitosan (CS) were integrated together via amidation reactions between the carboxyl groups on sodium CMC and the amino groups on CS. Compared with individual sodium CMC and CS, the integrated polysaccharides with a mass ratio of 1:1, CMC-CS (1:1), exhibited a three-dimensional (3D) porous network structure, resulting in a significantly enhanced hydrophility due to the exposed polar functional groups in the CMC-CS (1:1). Chiral interfaces were constructed with the integrated polysaccharides and used for electrochemical enantiorecognition of tryptophan (Trp) isomers. The CMC-CS (1:1) chiral interfaces exhibited excellent selectivity toward the Trp isomers owing to the highly hydrophilic feature of CMC-CS (1:1) and the different steric hindrance during the formation of H bonds between Trp isomers and CMC-CS (1:1). Also, the optimization in the preparation of integrated polysaccharides such as mass ratio and combination mode (amidation or electrostatic interactions) was investigated. The CMC-CS (1:1) presented the ability of determining the percentage of d-Trp in racemic mixtures, and thus, the proposed electrochemical chiral interfaces could be regarded as a potential biosensing platform for enantiorecognition of chiral compounds. PMID:27487166

  13. Chiral quantum supercrystals with total dissymmetry of optical response

    NASA Astrophysics Data System (ADS)

    Baimuratov, Anvar S.; Gun’Ko, Yurii K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-03-01

    Since chiral nanoparticles are much smaller than the optical wavelength, their enantiomers show little difference in the interaction with circularly polarized light. This scale mismatch makes the enhancement of enantioselectivity in optical excitation of nanoobjects a fundamental challenge in modern nanophotonics. Here we demonstrate that a strong dissymmetry of optical response from achiral nanoobjects can be achieved through their arrangement into chiral superstructures with the length scale comparable to the optical wavelength. This concept is illustrated by the example of the simple helix supercrystal made of semiconductor quantum dots. We show that this supercrystal almost fully absorbs light with one circular polarization and does not absorb the other. The giant circular dichroism of the supercrystal comes from the formation of chiral bright excitons, which are the optically active collective excitations of the entire supercrystal. Owing to the recent advances in assembly and self-organization of nanocrystals in large superparticle structures, the proposed principle of enantioselectivity enhancement has great potential of benefiting various chiral and analytical methods, which are used in biophysics, chemistry, and pharmaceutical science.

  14. Handedness Dependent Electromagnetically Induced Transparency in Hybrid Chiral Metamaterials

    PubMed Central

    Kang, Lei; Hao Jiang, Zhi; Yue, Taiwei; Werner, Douglas H.

    2015-01-01

    We provide the first experimental demonstration of the handedness dependent electromagnetically induced transparency (EIT) in chiral metamaterials during the interaction with circularly polarized waves. The observed chiral-sensitive EIT phenomena arise from the coherent excitation of a non-radiative mode in the component split ring resonators (SRRs) produced by the corresponding Born−Kuhn type (radiative) resonators that are responsible for the pronounced chirality. The coherent coupling, which is dominated by the bonding and antibonding resonances of the Born−Kuhn type resonators, leads to an extremely steep dispersion for a circularly polarized wave of predefined handedness. Accordingly, retrieved effective medium parameters from simulated results further reveal a difference of 80 in the group indices for left- and right-handed circularly polarized waves at frequencies within the EIT window, which can potentially result in handedness-sensitive pulse delays. These chiral metamaterials which enable a handedness dependent EIT effect may provide more degrees of freedom for designing circular polarization based communication devices. PMID:26183735

  15. Entanglement between deconfinement transition and chiral symmetry restoration

    SciTech Connect

    Sakai, Yuji; Sasaki, Takahiro; Yahiro, Masanobu; Kouno, Hiroaki

    2010-10-01

    We extend the Polyakov-loop extended Nambu-Jona-Lasinio model by introducing an effective four-quark vertex depending on the Polyakov loop. The effective vertex generates entanglement interactions between the Polyakov loop and the chiral condensate. The new model is consistent with lattice QCD data at imaginary quark-number chemical potential and real and imaginary isospin chemical potentials, particularly on the strong correlation between the chiral and deconfinement transitions and also on the quark-mass dependence of the order of the Roberge-Weiss endpoint. We investigate the influence of the entanglement interactions on the location of the tricritical point at real isospin chemical potential and on the location of the critical endpoint at real quark-number chemical potential.

  16. Weak Pion and Photon Production from Nuclei in a Chiral Effective Field Theory (Update)

    NASA Astrophysics Data System (ADS)

    Zhang, Xilin; Serot, Brian D.

    2011-04-01

    Neutrino-induced pion and photon production from nucleons and nuclei are important for the interpretation of neutrino-oscillation experiments. [A. A. Aquilar-Arevalo et al. (MiniBooNE Collaboration), Phys. Rev. Lett. 100, 032301 (2008)]. We have been working on these problems in a Lorentz-covariant effective field theory (known as QHD EFT), which contains nucleons, pions, Deltas (Δ), isoscalar scalar (σ) and vector (ω) fields, and isovector vector (ρ) fields and has nonlinear chiral symmetry built in. Here we update our results on weak pion and photon production from nuclei, including both incoherent and coherent scattering. Connections between our results and the background analysis from MiniBooNE will be presented. In particular, coherent production of photons will be emphasized, and the possible relevance to the low-energy excess events at MiniBooNE will be explored. To justify our approximation scheme, we compare our results with data for inclusive electron scattering off nuclei up to the Δ peak and with coherent photoproduction of pions. Finally, we focus on the approximation scheme used and discuss the important Δ dynamics in the medium. An interesting mechanism to generate the Δ's spin-orbit coupling in the nucleus will be introduced, together with its possible consequences. Supported in part by the Department of Energy under Contract No. DE-FG02-87ER40365.

  17. Local and global chirality at surfaces: succinic acid versus tartaric acid on Cu110.

    PubMed

    Humblot, Vincent; Lorenzo, Maria Ortega; Baddeley, Christopher J; Haq, Sam; Raval, Rasmita

    2004-05-26

    A detailed comparison of tartaric acid (HOOC-CHOH-CHOH-COOH) and succinic acid (HOOC-CH(2)-CH(2)-COOH) molecules on a Cu(110) surface is presented with a view to elucidate how the two-dimensional chirality exhibited by such robust, chemisorbed systems is affected when both OH groups of the former molecule are replaced with H groups, a stereochemical change that leaves the metal-bonding functionalities of the molecule untouched but destroys both chiral centers. It is found that this change does not significantly affect the thermodynamically preferred chemical forms that are adopted, namely the doubly deprotonated bicarboxylate at low coverages (theta chiral phases alter substantially. For both molecules, two-dimensional assembly is found to depend strongly on the nature of the local adsorption motif created, with each motif essentially acting as a "synthon" for the supramolecular assembly. In this respect, it seems that molecule-metal bonding interactions define the general self-assembly structure. The presence/absence of the OH groups, instead, cause a subtler, second-order effect on the finer details of the self-assembled structure. Finally, the creation of chirality in the achiral succinate system is shown to arise from adsorption-induced asymmetrization, inducing point chirality via molecular distortion and/or metal reconstruction of the local adsorption unit. This chiral adsorption unit is then responsible for creating chiral supramolecular through-space and through-metal interactions that propagate a chiral organization. However, the achirality of the succinate ensures that nucleation points of either chirality are equally created, producing a racemic conglomerate of coexisting mirror domains. It is in this aspect that the uniquely

  18. Lectures on Chiral Symmetries and Soft Pion Processes

    DOE R&D Accomplishments Database

    Nambu, Y.

    1966-08-01

    At the Istanbul Summer School in 1962 I gave lectures on "Chiral Symmetries in Weak and Strong Interactions." It is only recently, however, that the basic ideas that were started several years ago have begun to bear fruit. We will cover in the present lectures more or less the same general field, but certainly there will be a lot more results to be discussed now than four years ago.

  19. REVIEW ARTICLE: Chiral metamaterials: simulations and experiments

    NASA Astrophysics Data System (ADS)

    Wang, Bingnan; Zhou, Jiangfeng; Koschny, Thomas; Kafesaki, Maria; Soukoulis, Costas M.

    2009-11-01

    Electromagnetic metamaterials are composed of periodically arranged artificial structures. They show peculiar properties, such as negative refraction and super-lensing, which are not seen in natural materials. The conventional metamaterials require both negative epsilon and negative μ to achieve negative refraction. Chiral metamaterial is a new class of metamaterials offering a simpler route to negative refraction. In this paper, we briefly review the history of metamaterials and the developments on chiral metamaterials. We study the wave propagation properties in chiral metamaterials and show that negative refraction can be realized in chiral metamaterials with a strong chirality, with neither epsilon nor μ negative required. We have developed a retrieval procedure, adopting a uniaxial bi-isotropic model to calculate the effective parameters such as n ± , κ, epsilon and μ of the chiral metamaterials. Our work on the design, numerical calculations and experimental measurements of chiral metamaterials is introduced. Strong chiral behaviors such as optical activity and circular dichroism are observed and negative refraction is obtained for circularly polarized waves in these chiral metamaterials. We show that 3D isotropic chiral metamaterials can eventually be realized.

  20. Surface Stiffness--a Parameter for Sensing the Chirality of Saccharides.

    PubMed

    Lv, Ziyu; Li, Xiuling; Chen, Zhonghui; Chen, Ji; Chen, Cheng; Xiong, Peng; Sun, Taolei; Qing, Guangyan

    2015-12-16

    Surface stiffness is considered a key parameter for designing high-performance implantable materials and artificial extracellular matrices because of its substantial effects on cell behavior. How to transform biomolecule recognition events, particularly chiral recognition, into stiffness change on material surfaces is biologically essential but very challenging for chemists. Here, we report a chirality-triggered stiffness transition on a smart polymer film, which consists of flexible polyethylenimine (PEI) main chains grafted with dipeptide units capable of discriminating chiral monosaccharides. The polymer film became substantially softer after interacting with L-ribose and became more rigid after interacting with D-ribose (the basic building block of DNA and RNA). This chiral effect provides a new method for determining the enantiomeric purity of an L/D-ribose mixture and facilitates the chiral separation of deoxyribose racemates as well as the separation of diverse mono-, di-, and oligosaccharides. These are three puzzle problems in carbohydrate chemistry. Furthermore, taking advantage of the significant differences in the surface stiffness, the proliferation of fibroblast cells on the polymeric surfaces can also be regulated by chiral biomolecules. PMID:26595648

  1. Chiral logarithms in quenched QCD

    SciTech Connect

    Y. Chen; S. J. Dong; T. Draper; I. Horvath; F. X. Lee; K. F. Liu; N. Mathur; and J. B. Zhang

    2004-08-01

    The quenched chiral logarithms are examined on a 163x28 lattice with Iwasaki gauge action and overlap fermions. The pion decay constant fpi is used to set the lattice spacing, a = 0.200(3) fm. With pion mass as low as {approx}180 MeV, we see the quenched chiral logarithms clearly in mpi2/m and fP, the pseudoscalar decay constant. The authors analyze the data to determine how low the pion mass needs to be in order for the quenched one-loop chiral perturbation theory (chiPT) to apply. With the constrained curve-fitting method, they are able to extract the quenched chiral logarithmic parameter delta together with other low-energy parameters. Only for mpi<=300 MeV do we obtain a consistent and stable fit with a constant delta which they determine to be 0.24(3)(4) (at the chiral scale Lambdachi = 0.8 GeV). By comparing to the 123x28 lattice, they estimate the finite volume effect to be about 2.7% for the smallest pion mass. They also fitted the pion mass to the form for the re-summed cactus diagrams and found that its applicable region is extended farther than the range for the one-loop formula, perhaps up to mpi {approx}500-600 MeV. The scale independent delta is determined to be 0.20(3) in this case. The authors study the quenched non-analytic terms in the nucleon mass and find that the coefficient C1/2 in the nucleon mass is consistent with the prediction of one-loop chiPT. They also obtain the low energy constant L5 from fpi. They conclude from this study that it is imperative to cover only the range of data with the pion mass less than {approx}300 MeV in order to examine the chiral behavior of the hadron masses and decay constants in quenched QCD and match them with quenched one-loop chiPT.

  2. Mechanism of chirality conversion by periodic change of temperature: Role of chiral clusters

    NASA Astrophysics Data System (ADS)

    Katsuno, Hiroyasu; Uwaha, Makio

    2016-01-01

    By grinding crystals in a solution, the chirality of crystal structure (and the molecular chirality for the case of chiral molecules as well) can be converted, and the cause of the phenomenon is attributed to crystal growth with chiral clusters. We show that the recently found chirality conversion with a periodic change of temperature can also be explained by crystal growth with chiral clusters. With the use of a generalized Becker-Döring model, which includes enantio-selective incorporation of small chiral clusters to large solid clusters, the change of cluster distribution and the mass flow between clusters are studied. The chiral clusters act as a reservoir to pump out the minority species to the majority, and the exponential amplification of the enantiomeric excess found in the experiment is reproduced in the numerical calculation.

  3. The interplay of covalency, hydrogen bonding, and dispersion leads to a long range chiral network: The example of 2-butanol

    NASA Astrophysics Data System (ADS)

    Liriano, Melissa L.; Carrasco, Javier; Lewis, Emily A.; Murphy, Colin J.; Lawton, Timothy J.; Marcinkowski, Matthew D.; Therrien, Andrew J.; Michaelides, Angelos; Sykes, E. Charles H.

    2016-03-01

    The assembly of complex structures in nature is driven by an interplay between several intermolecular interactions, from strong covalent bonds to weaker dispersion forces. Understanding and ultimately controlling the self-assembly of materials requires extensive study of how these forces drive local nanoscale interactions and how larger structures evolve. Surface-based self-assembly is particularly amenable to modeling and measuring these interactions in well-defined systems. This study focuses on 2-butanol, the simplest aliphatic chiral alcohol. 2-butanol has recently been shown to have interesting properties as a chiral modifier of surface chemistry; however, its mode of action is not fully understood and a microscopic understanding of the role non-covalent interactions play in its adsorption and assembly on surfaces is lacking. In order to probe its surface properties, we employed high-resolution scanning tunneling microscopy and density functional theory (DFT) simulations. We found a surprisingly rich degree of enantiospecific adsorption, association, chiral cluster growth and ultimately long range, highly ordered chiral templating. Firstly, the chiral molecules acquire a second chiral center when adsorbed to the surface via dative bonding of one of the oxygen atom lone pairs. This interaction is controlled via the molecule's intrinsic chiral center leading to monomers of like chirality, at both chiral centers, adsorbed on the surface. The monomers then associate into tetramers via a cyclical network of hydrogen bonds with an opposite chirality at the oxygen atom. The evolution of these square units is surprising given that the underlying surface has a hexagonal symmetry. Our DFT calculations, however, reveal that the tetramers are stable entities that are able to associate with each other by weaker van der Waals interactions and tessellate in an extended square network. This network of homochiral square pores grows to cover the whole Au(111) surface. Our data

  4. The interplay of covalency, hydrogen bonding, and dispersion leads to a long range chiral network: The example of 2-butanol.

    PubMed

    Liriano, Melissa L; Carrasco, Javier; Lewis, Emily A; Murphy, Colin J; Lawton, Timothy J; Marcinkowski, Matthew D; Therrien, Andrew J; Michaelides, Angelos; Sykes, E Charles H

    2016-03-01

    The assembly of complex structures in nature is driven by an interplay between several intermolecular interactions, from strong covalent bonds to weaker dispersion forces. Understanding and ultimately controlling the self-assembly of materials requires extensive study of how these forces drive local nanoscale interactions and how larger structures evolve. Surface-based self-assembly is particularly amenable to modeling and measuring these interactions in well-defined systems. This study focuses on 2-butanol, the simplest aliphatic chiral alcohol. 2-butanol has recently been shown to have interesting properties as a chiral modifier of surface chemistry; however, its mode of action is not fully understood and a microscopic understanding of the role non-covalent interactions play in its adsorption and assembly on surfaces is lacking. In order to probe its surface properties, we employed high-resolution scanning tunneling microscopy and density functional theory (DFT) simulations. We found a surprisingly rich degree of enantiospecific adsorption, association, chiral cluster growth and ultimately long range, highly ordered chiral templating. Firstly, the chiral molecules acquire a second chiral center when adsorbed to the surface via dative bonding of one of the oxygen atom lone pairs. This interaction is controlled via the molecule's intrinsic chiral center leading to monomers of like chirality, at both chiral centers, adsorbed on the surface. The monomers then associate into tetramers via a cyclical network of hydrogen bonds with an opposite chirality at the oxygen atom. The evolution of these square units is surprising given that the underlying surface has a hexagonal symmetry. Our DFT calculations, however, reveal that the tetramers are stable entities that are able to associate with each other by weaker van der Waals interactions and tessellate in an extended square network. This network of homochiral square pores grows to cover the whole Au(111) surface. Our data

  5. The interplay of covalency, hydrogen bonding, and dispersion leads to a long range chiral network: The example of 2-butanol.

    PubMed

    Liriano, Melissa L; Carrasco, Javier; Lewis, Emily A; Murphy, Colin J; Lawton, Timothy J; Marcinkowski, Matthew D; Therrien, Andrew J; Michaelides, Angelos; Sykes, E Charles H

    2016-03-01

    The assembly of complex structures in nature is driven by an interplay between several intermolecular interactions, from strong covalent bonds to weaker dispersion forces. Understanding and ultimately controlling the self-assembly of materials requires extensive study of how these forces drive local nanoscale interactions and how larger structures evolve. Surface-based self-assembly is particularly amenable to modeling and measuring these interactions in well-defined systems. This study focuses on 2-butanol, the simplest aliphatic chiral alcohol. 2-butanol has recently been shown to have interesting properties as a chiral modifier of surface chemistry; however, its mode of action is not fully understood and a microscopic understanding of the role non-covalent interactions play in its adsorption and assembly on surfaces is lacking. In order to probe its surface properties, we employed high-resolution scanning tunneling microscopy and density functional theory (DFT) simulations. We found a surprisingly rich degree of enantiospecific adsorption, association, chiral cluster growth and ultimately long range, highly ordered chiral templating. Firstly, the chiral molecules acquire a second chiral center when adsorbed to the surface via dative bonding of one of the oxygen atom lone pairs. This interaction is controlled via the molecule's intrinsic chiral center leading to monomers of like chirality, at both chiral centers, adsorbed on the surface. The monomers then associate into tetramers via a cyclical network of hydrogen bonds with an opposite chirality at the oxygen atom. The evolution of these square units is surprising given that the underlying surface has a hexagonal symmetry. Our DFT calculations, however, reveal that the tetramers are stable entities that are able to associate with each other by weaker van der Waals interactions and tessellate in an extended square network. This network of homochiral square pores grows to cover the whole Au(111) surface. Our data

  6. Nanocatalyst structure as a template to define chirality of nascent single-walled carbon nanotubes.

    PubMed

    Gómez-Gualdrón, Diego A; Zhao, Jin; Balbuena, Perla B

    2011-01-01

    Chirality is a crucial factor in a single-walled carbon nanotube (SWCNT) because it determines its optical and electronic properties. A chiral angle spanning from 0° to 30° results from twisting of the graphene sheet conforming the nanotube wall and is equivalently expressed by chiral indexes (n,m). However, lack of chirality control during SWCNT synthesis is an obstacle for a widespread use of these materials. Here we use first-principles density functional theory (DFT) and classical molecular dynamics (MD) simulations to propose and illustrate basic concepts supporting that the nanocatalyst structure may act as a template to control the chirality during nanotube synthesis. DFT optimizations of metal cluster (Co and Cu)∕cap systems for caps of various chiralities are used to show that an inverse template effect from the nascent carbon nanostructure over the catalyst may exist in floating catalysts; such effect determines a negligible chirality control. Classical MD simulations are used to investigate the influence of a strongly interacting substrate on the structure of a metal nanocatalyst and illustrate how such interaction may help preserve catalyst crystallinity. Finally, DFT optimizations of carbon structures on stepped (211) and (321) cobalt surfaces are used to demonstrate the template effect imparted by the nanocatalyst surface on the growing carbon structure at early stages of nucleation. It is found that depending on the step structure and type of building block (short chains, single atoms, or hexagonal rings), thermodynamics favor armchair or zigzag termination, which provides guidelines for a chirality controlled process based on tuning the catalyst structure and the type of precursor gas. PMID:21219018

  7. Nanocatalyst structure as a template to define chirality of nascent single-walled carbon nanotubes.

    PubMed

    Gómez-Gualdrón, Diego A; Zhao, Jin; Balbuena, Perla B

    2011-01-01

    Chirality is a crucial factor in a single-walled carbon nanotube (SWCNT) because it determines its optical and electronic properties. A chiral angle spanning from 0° to 30° results from twisting of the graphene sheet conforming the nanotube wall and is equivalently expressed by chiral indexes (n,m). However, lack of chirality control during SWCNT synthesis is an obstacle for a widespread use of these materials. Here we use first-principles density functional theory (DFT) and classical molecular dynamics (MD) simulations to propose and illustrate basic concepts supporting that the nanocatalyst structure may act as a template to control the chirality during nanotube synthesis. DFT optimizations of metal cluster (Co and Cu)∕cap systems for caps of various chiralities are used to show that an inverse template effect from the nascent carbon nanostructure over the catalyst may exist in floating catalysts; such effect determines a negligible chirality control. Classical MD simulations are used to investigate the influence of a strongly interacting substrate on the structure of a metal nanocatalyst and illustrate how such interaction may help preserve catalyst crystallinity. Finally, DFT optimizations of carbon structures on stepped (211) and (321) cobalt surfaces are used to demonstrate the template effect imparted by the nanocatalyst surface on the growing carbon structure at early stages of nucleation. It is found that depending on the step structure and type of building block (short chains, single atoms, or hexagonal rings), thermodynamics favor armchair or zigzag termination, which provides guidelines for a chirality controlled process based on tuning the catalyst structure and the type of precursor gas.

  8. Recent Theoretical and Experimental Advances in the Electronic Circular Dichroisms of Planar Chiral Cyclophanes

    NASA Astrophysics Data System (ADS)

    Mori, Tadashi; Inoue, Yoshihisa

    The chiroptical properties, such as electronic and vibrational circular dichroism and optical rotation, of planar chiral cyclophanes have attracted much attention in recent years. Although the chemistry of cyclophanes has been extensively explored for more than 60 years, the studies on chiral cyclophanes are rather limited. Experimentally, the use of chiral stationary phases in HPLC becomes more popular and facilitates the enantiomer separation of chiral cyclophanes of interest. Almost all chiral cyclophanes can be readily separated, in analytical and preparative scales, most typically on a Daicel OD type column, which is based on cellulose tris(3,5-dimethylphenylcarbamate). The CD spectra of chiral cyclophanes are unique in their fairly large, significantly coupled Cotton effects observed in all the 1 B b, 1 L a, and 1 L b band regions. Theoretically, the time-dependent density functional theory, or TD-DFT, method becomes a cost-efficient, yet accurate, theoretical method to reproduce the electronic circular dichroisms and the absorption spectra of a variety of cyclophanes. The direct comparison of the experimental CD spectra with the theoretical ones readily leads to the unambiguous assignment of the absolute configuration of cyclophanes. In addition, the analysis of configuration interaction and molecular orbitals allows detailed interpretation of the electronic transitions and Cotton effects in the UV and CD spectra. Through the study of the CD spectra of chiral cyclophanes as model systems, the effects of intra- and intermolecular interactions on the chiroptical properties of molecules can be explored, and the results thus obtained are valuable in comprehensively elucidating the structure-chiroptical property relationship. In this review the recent progress in experimental and theoretical investigations of the electronic CD spectra of chiral cyclophanes is discussed.

  9. Electric-field-induced assembly and propulsion of chiral colloidal clusters.

    PubMed

    Ma, Fuduo; Wang, Sijia; Wu, David T; Wu, Ning

    2015-05-19

    Chiral molecules with opposite handedness exhibit distinct physical, chemical, or biological properties. They pose challenges as well as opportunities in understanding the phase behavior of soft matter, designing enantioselective catalysts, and manufacturing single-handed pharmaceuticals. Microscopic particles, arranged in a chiral configuration, could also exhibit unusual optical, electric, or magnetic responses. Here we report a simple method to assemble achiral building blocks, i.e., the asymmetric colloidal dimers, into a family of chiral clusters. Under alternating current electric fields, two to four lying dimers associate closely with a central standing dimer and form both right- and left-handed clusters on a conducting substrate. The cluster configuration is primarily determined by the induced dipolar interactions between constituent dimers. Our theoretical model reveals that in-plane dipolar repulsion between petals in the cluster favors the achiral configuration, whereas out-of-plane attraction between the central dimer and surrounding petals favors a chiral arrangement. It is the competition between these two interactions that dictates the final configuration. The theoretical chirality phase diagram is found to be in excellent agreement with experimental observations. We further demonstrate that the broken symmetry in chiral clusters induces an unbalanced electrohydrodynamic flow surrounding them. As a result, they rotate in opposite directions according to their handedness. Both the assembly and propulsion mechanisms revealed here can be potentially applied to other types of asymmetric particles. Such kinds of chiral colloids will be useful for fabricating metamaterials, making model systems for both chiral molecules and active matter, or building propellers for microscale transport.

  10. Electric-field–induced assembly and propulsion of chiral colloidal clusters

    PubMed Central

    Ma, Fuduo; Wang, Sijia; Wu, David T.; Wu, Ning

    2015-01-01

    Chiral molecules with opposite handedness exhibit distinct physical, chemical, or biological properties. They pose challenges as well as opportunities in understanding the phase behavior of soft matter, designing enantioselective catalysts, and manufacturing single-handed pharmaceuticals. Microscopic particles, arranged in a chiral configuration, could also exhibit unusual optical, electric, or magnetic responses. Here we report a simple method to assemble achiral building blocks, i.e., the asymmetric colloidal dimers, into a family of chiral clusters. Under alternating current electric fields, two to four lying dimers associate closely with a central standing dimer and form both right- and left-handed clusters on a conducting substrate. The cluster configuration is primarily determined by the induced dipolar interactions between constituent dimers. Our theoretical model reveals that in-plane dipolar repulsion between petals in the cluster favors the achiral configuration, whereas out-of-plane attraction between the central dimer and surrounding petals favors a chiral arrangement. It is the competition between these two interactions that dictates the final configuration. The theoretical chirality phase diagram is found to be in excellent agreement with experimental observations. We further demonstrate that the broken symmetry in chiral clusters induces an unbalanced electrohydrodynamic flow surrounding them. As a result, they rotate in opposite directions according to their handedness. Both the assembly and propulsion mechanisms revealed here can be potentially applied to other types of asymmetric particles. Such kinds of chiral colloids will be useful for fabricating metamaterials, making model systems for both chiral molecules and active matter, or building propellers for microscale transport. PMID:25941383

  11. Electric-field-induced assembly and propulsion of chiral colloidal clusters.

    PubMed

    Ma, Fuduo; Wang, Sijia; Wu, David T; Wu, Ning

    2015-05-19

    Chiral molecules with opposite handedness exhibit distinct physical, chemical, or biological properties. They pose challenges as well as opportunities in understanding the phase behavior of soft matter, designing enantioselective catalysts, and manufacturing single-handed pharmaceuticals. Microscopic particles, arranged in a chiral configuration, could also exhibit unusual optical, electric, or magnetic responses. Here we report a simple method to assemble achiral building blocks, i.e., the asymmetric colloidal dimers, into a family of chiral clusters. Under alternating current electric fields, two to four lying dimers associate closely with a central standing dimer and form both right- and left-handed clusters on a conducting substrate. The cluster configuration is primarily determined by the induced dipolar interactions between constituent dimers. Our theoretical model reveals that in-plane dipolar repulsion between petals in the cluster favors the achiral configuration, whereas out-of-plane attraction between the central dimer and surrounding petals favors a chiral arrangement. It is the competition between these two interactions that dictates the final configuration. The theoretical chirality phase diagram is found to be in excellent agreement with experimental observations. We further demonstrate that the broken symmetry in chiral clusters induces an unbalanced electrohydrodynamic flow surrounding them. As a result, they rotate in opposite directions according to their handedness. Both the assembly and propulsion mechanisms revealed here can be potentially applied to other types of asymmetric particles. Such kinds of chiral colloids will be useful for fabricating metamaterials, making model systems for both chiral molecules and active matter, or building propellers for microscale transport. PMID:25941383

  12. Stable Pentaquarks from Strange Chiral Multiplets

    SciTech Connect

    Silas Beane

    2004-12-01

    The assumption of strong diquark correlations in the QCD spectrum suggests flavor multiplets of hadrons that are degenerate in the chiral limit. Generally it would be unnatural for there to be degeneracy in the hadron spectrum that is not protected by a QCD symmetry. Here we show--for pentaquarks constructed from diquarks--that these degeneracies can be naturally protected by the full chiral symmetry of QCD. The resulting chiral multiplet structure recovers the ideally-mixed pentaquark mass spectrum of the diquark model, and interestingly, requires that the axial couplings of the pentaquarks to states outside the degenerate multiplets vanish in the chiral limit. This result suggests that if these hadrons exist, they are stable in the chiral limit and therefore have widths that scale as the fourth power of the kaon mass over the chiral symmetry breaking scale. Natural-size widths are of order a few MeV.

  13. Asymmetric synthesis using chiral-encoded metal.

    PubMed

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-08-26

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity.

  14. Asymmetric synthesis using chiral-encoded metal.

    PubMed

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-01-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity. PMID:27562028

  15. Anomalous Maxwell equations for inhomogeneous chiral plasma

    NASA Astrophysics Data System (ADS)

    Gorbar, E. V.; Shovkovy, I. A.; Vilchinskii, S.; Rudenok, I.; Boyarsky, A.; Ruchayskiy, O.

    2016-05-01

    Using the chiral kinetic theory we derive the electric and chiral current densities in inhomogeneous relativistic plasma. We also derive equations for the electric and chiral chemical potentials that close the Maxwell equations in such a plasma. The analysis is done in the regimes with and without a drift of the plasma as a whole. In addition to the currents present in the homogeneous plasma (Hall current, chiral magnetic, chiral separation, and chiral electric separation effects, as well as Ohm's current) we derive several new terms associated with inhomogeneities of the plasma. Apart from various diffusionlike terms, we find also new dissipationless terms that are independent of relaxation time. Their origin can be traced to the Berry curvature modifications of the kinetic theory.

  16. Asymmetric synthesis using chiral-encoded metal

    PubMed Central

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-01-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity. PMID:27562028

  17. Asymmetric synthesis using chiral-encoded metal

    NASA Astrophysics Data System (ADS)

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-08-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity.

  18. Enantioselective recognition at mesoporous chiral metal surfaces

    PubMed Central

    Wattanakit, Chularat; Côme, Yémima Bon Saint; Lapeyre, Veronique; Bopp, Philippe A.; Heim, Matthias; Yadnum, Sudarat; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2014-01-01

    Chirality is widespread in natural systems, and artificial reproduction of chiral recognition is a major scientific challenge, especially owing to various potential applications ranging from catalysis to sensing and separation science. In this context, molecular imprinting is a well-known approach for generating materials with enantioselective properties, and it has been successfully employed using polymers. However, it is particularly difficult to synthesize chiral metal matrices by this method. Here we report the fabrication of a chirally imprinted mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and chiral template molecules. The porous platinum retains a chiral character after removal of the template molecules. A matrix obtained in this way exhibits a large active surface area due to its mesoporosity, and also shows a significant discrimination between two enantiomers, when they are probed using such materials as electrodes. PMID:24548992

  19. Effective field theory of thermal Casimir interactions between anisotropic particles.

    PubMed

    Haussman, Robert C; Deserno, Markus

    2014-06-01

    We employ an effective field theory (EFT) approach to study thermal Casimir interactions between objects bound to a fluctuating fluid surface or interface dominated by surface tension, with a focus on the effects of particle anisotropy. The EFT prescription disentangles the constraints imposed by the particles' boundaries from the calculation of the interaction free energy by constructing an equivalent point particle description. The finite-size information is captured in a derivative expansion that encodes the particles' response to external fields. The coefficients of the expansion terms correspond to generalized tensorial polarizabilities and are found by matching the results of a linear response boundary value problem computed in both the full and effective theories. We demonstrate the versatility of the EFT approach by constructing the general effective Hamiltonian for a collection of particles of arbitrary shapes. Taking advantage of the conformal symmetry of the Hamiltonian, we discuss a straightforward conformal mapping procedure to systematically determine the polarizabilities and derive a complete description for elliptical particles. We compute the pairwise interaction energies to several orders for nonidentical ellipses as well as their leading-order triplet interactions and discuss the resulting preferred pair and multibody configurations. Furthermore, we elaborate on the complications that arise with pinned particle boundary conditions and show that the powerlike corrections expected from dimensional analysis are exponentially suppressed by the leading-order interaction energies. PMID:25019720

  20. On chirality of slime mould.

    PubMed

    Dimonte, Alice; Adamatzky, Andrew; Erokhin, Victor; Levin, Michael

    2016-02-01

    Left-right patterning and lateralised behaviour is an ubiquitous aspect of plants and animals. The mechanisms linking cellular chirality to the large-scale asymmetry of multicellular structures are incompletely understood, and it has been suggested that the chirality of living cells is hardwired in their cytoskeleton. We examined the question of biased asymmetry in a unique organism: the slime mould Physarum polycephalum, which is unicellular yet possesses macroscopic, complex structure and behaviour. In laboratory experiment using a T-shape, we found that Physarum turns right in more than 74% of trials. The results are in agreement with previously published studies on asymmetric movement of muscle cells, neutrophils, liver cells and growing neural filaments, and for the first time reveal the presence of consistently-biased laterality in the fungi kingdom. Exact mechanisms of the slime mould's direction preference remain unknown.

  1. On chirality of slime mould.

    PubMed

    Dimonte, Alice; Adamatzky, Andrew; Erokhin, Victor; Levin, Michael

    2016-02-01

    Left-right patterning and lateralised behaviour is an ubiquitous aspect of plants and animals. The mechanisms linking cellular chirality to the large-scale asymmetry of multicellular structures are incompletely understood, and it has been suggested that the chirality of living cells is hardwired in their cytoskeleton. We examined the question of biased asymmetry in a unique organism: the slime mould Physarum polycephalum, which is unicellular yet possesses macroscopic, complex structure and behaviour. In laboratory experiment using a T-shape, we found that Physarum turns right in more than 74% of trials. The results are in agreement with previously published studies on asymmetric movement of muscle cells, neutrophils, liver cells and growing neural filaments, and for the first time reveal the presence of consistently-biased laterality in the fungi kingdom. Exact mechanisms of the slime mould's direction preference remain unknown. PMID:26747637

  2. On lattice chiral gauge theories

    NASA Technical Reports Server (NTRS)

    Maiani, L.; Rossi, G. C.; Testa, M.

    1991-01-01

    The Smit-Swift-Aoki formulation of a lattice chiral gauge theory is presented. In this formulation the Wilson and other non invariant terms in the action are made gauge invariant by the coupling with a nonlinear auxilary scalar field, omega. It is shown that omega decouples from the physical states only if appropriate parameters are tuned so as to satisfy a set of BRST identities. In addition, explicit ghost fields are necessary to ensure decoupling. These theories can give rise to the correct continuum limit. Similar considerations apply to schemes with mirror fermions. Simpler cases with a global chiral symmetry are discussed and it is shown that the theory becomes free at decoupling. Recent numerical simulations agree with those considerations.

  3. Optically controllable THz chiral metamaterials.

    PubMed

    Kenanakis, G; Zhao, R; Katsarakis, N; Kafesaki, M; Soukoulis, C M; Economou, E N

    2014-05-19

    Switchable and tunable chiral metamaterial response is numerically demonstrated here in different uniaxial chiral metamaterial structures operating in the THz regime. The structures are based on the bi-layer conductor design and the tunable/switchable response is achieved by replacing parts of the metallic components of the structures by photoconducting Si, which can be transformed from an insulating to an almost conducting state through photoexcitation, achievable under external optical pumping. All the structures proposed and discussed here exhibit frequency regions with giant tunable circular dichroism, as well as regions with giant tunable optical activity, showing unique potential in the achievement of active THz polarization components, like tunable polarizers and polarization filters. PMID:24921336

  4. Bootstrapping N=2 chiral correlators

    NASA Astrophysics Data System (ADS)

    Lemos, Madalena; Liendo, Pedro

    2016-01-01

    We apply the numerical bootstrap program to chiral operators in four-dimensional N=2 SCFTs. In the first part of this work we study four-point functions in which all fields have the same conformal dimension. We give special emphasis to bootstrapping a specific theory: the simplest Argyres-Douglas fixed point with no flavor symmetry. In the second part we generalize our setup and consider correlators of fields with unequal dimension. This is an example of a mixed correlator and allows us to probe new regions in the parameter space of N=2 SCFTs. In particular, our results put constraints on relations in the Coulomb branch chiral ring and on the curvature of the Zamolodchikov metric.

  5. Chiral anomaly, bosonization, and fractional charge

    SciTech Connect

    Mignaco, J.A.; Monteiro, M.A.R.

    1985-06-15

    We present a method to evaluate the Jacobian of chiral rotations, regulating determinants through the proper-time method and using Seeley's asymptotic expansion. With this method we compute easily the chiral anomaly for ..nu.. = 4,6 dimensions, discuss bosonization of some massless two-dimensional models, and handle the problem of charge fractionization. In addition, we comment on the general validity of Fujikawa's approach to regulate the Jacobian of chiral rotations with non-Hermitian operators.

  6. Thin-wire scatterers in chiral media.

    PubMed

    Jaggard, D L; Liu, J C; Grot, A; Pelet, P

    1991-06-01

    The effect of the handedness of chiral materials on the differential scattering cross section of embedded conducting wires is examined. The bow-tie-shaped induced current distributions and the resulting forbidden zone of radiation are explained through fundamental physical principles. We find that thin-wire scatterers can be divided into subchiral, chiral, and superchiral classes according to the degree of chirality of the host material and the electromagnetic length of the wire.

  7. Chirality operators for Heisenberg spin systems

    SciTech Connect

    Subrahmanyam, V. )

    1994-09-01

    The ground state of closed Heisenberg spin chains with an odd number of sites has a chiral degeneracy, in addition to a twofold Kramers degeneracy. A nonzero chirality implies that the spins are not coplanar, and is a measure of handedness. The chirality operator, which can be treated as a spin-1/2 operator, is explicitly constructed in terms of the spin operators, and is given as commutator of permutation operators.

  8. Flat-space chiral gravity.

    PubMed

    Bagchi, Arjun; Detournay, Stéphane; Grumiller, Daniel

    2012-10-12

    We provide the first evidence for a holographic correspondence between a gravitational theory in flat space and a specific unitary field theory in one dimension lower. The gravitational theory is a flat-space limit of topologically massive gravity in three dimensions at a Chern-Simons level of k=1. The field theory is a chiral two-dimensional conformal field theory with a central charge of c=24. PMID:23102291

  9. Anomalies and Discrete Chiral Symmetries

    SciTech Connect

    Creutz, M.

    2009-09-07

    The quantum anomaly that breaks the U(1) axial symmetry of massless multi-flavored QCD leaves behind a discrete flavor-singlet chiral invariance. With massive quarks, this residual symmetry has a close connection with the strong CP-violating parameter theta. One result is that if the lightest quarks are degenerate, then a first order transition will occur when theta passes through pi. The resulting framework helps clarify when the rooting prescription for extrapolating in the number of flavors is valid.

  10. Staggered chiral random matrix theory

    SciTech Connect

    Osborn, James C.

    2011-02-01

    We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.

  11. Chiral symmetry and nucleon structure

    SciTech Connect

    Holstein, B.R. . Dept. of Physics and Astromony Washington Univ., Seattle, WA . Inst. for Nuclear Theory)

    1992-01-01

    Recently it has been realized that significant tests of the validity of QCD are available in low energy experiments (E < 500 MeV) by exploiting the property of (broken) chiral symmetry. This technique has been highly developed in The Goldstone boson sector by the work of Gasser and Leutwyler. Application to the nucleon system is much more difficult and is now being carefully developed.

  12. Chiral methyl-branched pheromones.

    PubMed

    Ando, Tetsu; Yamakawa, Rei

    2015-07-01

    Insect pheromones are some of the most interesting natural products because they are utilized for interspecific communication between various insects, such as beetles, moths, ants, and cockroaches. A large number of compounds of many kinds have been identified as pheromone components, reflecting the diversity of insect species. While this review deals only with chiral methyl-branched pheromones, the chemical structures of more than one hundred non-terpene compounds have been determined by applying excellent analytical techniques. Furthermore, their stereoselective syntheses have been achieved by employing trustworthy chiral sources and ingenious enantioselective reactions. The information has been reviewed here not only to make them available for new research but also to understand the characteristic chemical structures of the chiral pheromones. Since biosynthetic studies are still limited, it might be meaningful to examine whether the structures, particularly the positions and configurations of the branched methyl groups, are correlated with the taxonomy of the pheromone producers and also with the function of the pheromones in communication systems. PMID:25849023

  13. Lateral chirality-sorting optical forces.

    PubMed

    Hayat, Amaury; Mueller, J P Balthasar; Capasso, Federico

    2015-10-27

    The transverse component of the spin angular momentum of evanescent waves gives rise to lateral optical forces on chiral particles, which have the unusual property of acting in a direction in which there is neither a field gradient nor wave propagation. Because their direction and strength depends on the chiral polarizability of the particle, they act as chirality-sorting and may offer a mechanism for passive chirality spectroscopy. The absolute strength of the forces also substantially exceeds that of other recently predicted sideways optical forces. PMID:26453555

  14. Generation of a Chiral Giant Micelle.

    PubMed

    Ito, Thiago H; Salles, Airton G; Priebe, Jacks P; Miranda, Paulo C M L; Morgon, Nelson H; Danino, Dganit; Mancini, Giovanna; Sabadini, Edvaldo

    2016-08-23

    Over the past few years, chiral supramolecular assemblies have been successfully used for recognition, sensing and enantioselective transformations. Several approaches are available to control chirality of discrete assemblies (e.g., cages and capsules), but few are efficient in assuring chirality for micellar aggregates. Optically active amino acid-derived surfactants are commonly used to generate chiral spherical micelles. To circumvent this limitation, we benefited from the uniaxial growth of spherical micelles into long cylindrical micelles usually called wormlike or giant micelles, upon the addition of cosolutes. This paper describes the unprecedented formation of chiral giant micelles in aqueous solutions of cetyltrimethylammonium bromide (CTAB) upon increasing addition of enantiopure sodium salt of 1,1'-bi-2-naphthol (Na-binaphtholate) as a cosolute. Depending on the concentrations of CTAB and Na-binaphtholate, chiral gel-like systems are obtained. The transition from spherical to giant micellar structures was probed using rheology, cryo-transmission electron microscopy, polarimetry, and electronic circular dichroism (CD). CD can be effectively used to monitor the incorporation of Na-binaphtholate into the micelle palisade as well as to determine its transition to giant micellar structures. Our approach expands the scope for chirality induction in micellar aggregates bringing the possibility to generate "smart" chiral systems and an alternative asymmetric chiral environment to perform enantioselective transformations. PMID:27499127

  15. Highly Phosphorescent Crystals of Square-Planar Platinum Complexes with Chiral Organometallic Linkers: Homochiral versus Heterochiral Arrangements, Induced Circular Dichroism, and TD-DFT Calculations.

    PubMed

    Sesolis, Hugo; Dubarle-Offner, Julien; Chan, Carmen K M; Puig, Emmanuel; Gontard, Geoffrey; Winter, Pierre; Cooksy, Andrew L; Yam, Vivian W W; Amouri, Hani

    2016-06-01

    A novel class of chiral luminescent square-planar platinum complexes with a π-bonded chiral thioquinonoid ligand is described. Remarkably the presence of this chiral organometallic ligand controls the aggregation of this square planar luminophor and imposes a homo- or hetero-chiral arrangement at the supramolecular level, displaying non-covalent Pt-Pt and π-π interactions. Interestingly these complexes are highly luminescent in the crystalline state and their photophysical properties can be traced to their aggregation in the solid state. A TD-DFT calculation is obtained to rationalize this unique behavior. PMID:27142245

  16. Chiral Bosonic Phases on the Haldane Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Vasic, Ivana; Petrescu, Alexandru; Le Hur, Karyn; Hofstetter, Walter; Collaboration Collaboration

    2015-03-01

    Motivated by its recent realization in an ultracold atom experiment, we investigate the honeycomb lattice tight-binding model introduced by Haldane, for bosons with local interactions at the average filling of one boson per site. We uncover in the ground state phase diagram three phases: a uniform superfluid (SF), a chiral superfluid (CSF) and a plaquette Mott insulator with local current loops (PMI). Nearest-neighbor and next-nearest neighbor currents distinguish CSF from SF, and the phase transition between them is first order. We apply bosonic dynamical mean field theory and exact diagonalization to obtain the zero temperature phase diagram, complementing numerics with calculations of excitation spectra in strong and weak coupling perturbation theory. Furthermore, we explore the possibility of chiral Mott insulating phases at the average filling of one boson every two sites. The characteristic density fluctuations, current correlation functions, and excitation spectra are measurable in ultracold atom experiments.

  17. Shear-Induced Chiral Migration of Particles with Anisotropic Rigidity

    NASA Astrophysics Data System (ADS)

    Watari, Nobuhiko; Larson, Ronald G.

    2009-06-01

    We report that an achiral particle with anisotropic rigidity can migrate in the vorticity direction in shear flow. A minimal “tetrumbbell” model of such a particle is constructed from four beads and six springs to make a tetrahedral structure. A combination of two different spring constants corresponding to “hard” and “soft” springs yields ten distinguishable tetrumbbells, which when simulated in shear flow with hydrodynamic interactions between beads but no Brownian motion at zero Reynolds number, produces five different types of behavior in which seven out of ten tetrumbbell structures migrate in the vorticity direction due to shear-induced chirality. Some of the structures migrate in the same direction along the vorticity direction even when the shear flow is reversed, which is impossible for permanently chiral objects.

  18. Self-organization of atoms coupled to a chiral reservoir

    NASA Astrophysics Data System (ADS)

    Eldredge, Zachary; Jarzynski, Christopher; Chang, Darrick; Gorshkov, Alexey

    2016-05-01

    Tightly confined modes of light, as in optical nanofibers or photonics crystal waveguides, can lead to large optical coupling in atomic systems, which mediates long-range interactions between atoms. These one-dimensional systems can naturally possess couplings which are asymmetric between modes in different directions. In this poster, we examine the self-organizing behavior of atoms in one dimension coupled to a chiral reservoir. We determine the behavior of the self-organized solution to the equations of motion in different parameter regimes, relative to both the detuning of the pump laser and the degree of reservoir chirality. In addition to the spatial configuration of self-organized atoms, we calculate possible experimental signatures.

  19. Spontaneous curvature in chiral polar filaments near interfaces

    NASA Astrophysics Data System (ADS)

    Olmsted, Peter D.; Riley, Emily E.; Jordens, Sophia; Usov, Ivan; Isa, Lucio; Mezzenga, Raffaele

    2015-03-01

    Chiral filaments (actin, DNA, alpha helical strands, ...) are ubiquitous in biology, and they frequently come into contact with interfaces or inhomogeneous environments, either in biology (e.g. actin on membranes) or use and processing of biomaterials (fibrils at solvent boundaries or nanoparticle surfaces). Recent experiments have shown that amyloid fibrils can develop unusual curvatures at the air-water interface. Here we show that spontaneous curvature follows, on symmetry grounds, for chiral polar filaments placed in inhomgeneous environments such as near surfaces. We demonstrate this for simple model surface-fibril interactions, and discuss some of the implications. Financial support is acknowledged from: ETH Zurich (ETHIIRA TH 32-1), SNF (2-77002-11), and SNSF (IZK072_141955, PP00P2_144646/1, PZ00P2_142532/1).

  20. Footprint organization of chiral molecules on metallic surfaces

    NASA Astrophysics Data System (ADS)

    Uñac, R. O.; Rabaza, A. V. Gil; Vidales, A. M.; Zgrablich, G.

    2007-10-01

    We study the behavior of chiral molecules adsorbed on clean metallic surfaces using a lattice-gas model and Monte Carlo simulation. The aim is to model and simulate the structure (footprints and organization) formed by molecules on the surface as they adsorb. The model, which is applicable to chiral species like S- and R-alanine, or similar, discloses the conditions to generate different ordered phases that have been observed in experiments by other authors. In our model, each enantiomer may adsorb in two different configurations (species) and several effects are taken into account: inhibition, blockage of neighboring adsorptive sites (steric effects) and promotion of sites representing, in some sense, modifications in the surface properties due to molecule-surface interactions. These adsorption rules are inspired by the enantiomeric character of adsorbed species. We perform a systematic study of the different phases formed in order to qualitatively understand the mechanism for the formation of adsorbate structures experimentally found by other authors.

  1. Chirality-Dependent Transmission of Spin Waves through Domain Walls

    NASA Astrophysics Data System (ADS)

    Buijnsters, F. J.; Ferreiros, Y.; Fasolino, A.; Katsnelson, M. I.

    2016-04-01

    Spin-wave technology (magnonics) has the potential to further reduce the size and energy consumption of information-processing devices. In the submicrometer regime (exchange spin waves), topological defects such as domain walls may constitute active elements to manipulate spin waves and perform logic operations. We predict that spin waves that pass through a domain wall in an ultrathin perpendicular-anisotropy film experience a phase shift that depends on the orientation of the domain wall (chirality). The effect, which is absent in bulk materials, originates from the interfacial Dzyaloshinskii-Moriya interaction and can be interpreted as a geometric phase. We demonstrate analytically and by means of micromagnetic simulations that the phase shift is strong enough to switch between constructive and destructive interference. The two chirality states of the domain wall may serve as a memory bit or spin-wave switch in magnonic devices.

  2. Chiral Thirring–Wess model with Faddeevian regularization

    SciTech Connect

    Rahaman, Anisur

    2015-03-15

    Replacing vector type of interaction of the Thirring–Wess model by the chiral type a new model is presented which is termed here as chiral Thirring–Wess model. Ambiguity parameters of regularization are so chosen that the model falls into the Faddeevian class. The resulting Faddeevian class of model in general does not possess Lorentz invariance. However we can exploit the arbitrariness admissible in the ambiguity parameters to relate the quantum mechanically generated ambiguity parameters with the classical parameter involved in the masslike term of the gauge field which helps to maintain physical Lorentz invariance instead of the absence of manifestly Lorentz covariance of the model. The phase space structure and the theoretical spectrum of this class of model have been determined through Dirac’s method of quantization of constraint system.

  3. The formation of right-handed and left-handed chiral nanopores within a single domain during amino acid self-assembly on Au(111).

    PubMed

    Yang, Sena; Jeon, Aram; Driver, Russell W; Kim, Yeonwoo; Jeon, Eun Hee; Kim, Sehun; Lee, Hee-Seung; Lee, Hangil

    2016-05-25

    We report the formation of both right- and left-handed chiral nanopores within a single domain during the self-assembly of an amino acid derivative on an inert Au(111) surface using STM. DFT calculations employed to rationalize this unusual result identified that intermolecular interactions between chiral, windmill-shaped tetramers are crucial for self-assembly.

  4. Origin of Stereodivergence in Cooperative Asymmetric Catalysis with Simultaneous Involvement of Two Chiral Catalysts.

    PubMed

    Bhaskararao, Bangaru; Sunoj, Raghavan B

    2015-12-23

    Accomplishing high diastereo- and enantioselectivities simultaneously is a persistent challenge in asymmetric catalysis. The use of two chiral catalysts in one-pot conditions might offer new avenues to this end. Chirality transfer from a catalyst to product gets increasingly complex due to potential chiral match-mismatch issues. The origin of high enantio- and diastereoselectivities in the reaction between a racemic aldehyde and an allyl alcohol, catalyzed by using axially chiral iridium phosphoramidites PR/S-Ir and cinchona amine is established through transition-state modeling. The multipoint contact analysis of the stereocontrolling transition state revealed how the stereodivergence could be achieved by inverting the configuration of the chiral catalysts that are involved in the activation of the reacting partners. While the enantiocontrol is identified as being decided in the generation of PR/S-Ir-π-allyl intermediate from the allyl alcohol, the diastereocontrol arises due to the differential stabilizations in the C-C bond formation transition states. The analysis of the weak interactions in the transition states responsible for chiral induction revealed that the geometric disposition of the quinoline ring at the C8 chiral carbon of cinchona-enamine plays an anchoring role. The quinolone ring is noted as participating in a π-stacking interaction with the phenyl ring of the Ir-π-allyl moiety in the case of PR with the (8R,9R)-cinchona catalyst combination, whereas a series of C-H···π interactions is identified as vital to the relative stabilization of the stereocontrolling transition states when PR is used with (8S,9S)-cinchona.

  5. Parity-Violating Neutron Spin Rotation in Hydrogen and Deuterium and the Predictive Power of EFT

    NASA Astrophysics Data System (ADS)

    Griesshammer, Harald W.

    2013-10-01

    One of the least-explored sectors of the Standard Model is the weak part of the nuclear force. Experiments on hadronic parity-violation (PV) at low energies require one comprehensive theoretical framework with reliable error-estimates to: check data consistency; subtract binding effects; and extract the PV interaction strengths. ``Pion-less'' Effective Field Theory is such a method with minimal theoretical bias. Different PV parameters are probed in np and nd spin rotation. Using naïve dimensional analysis, the signal for standard target densities is. An estimate of the numerical and systematic uncertainties of our calculations indicates excellent convergence. We also show that PV 3-nucleon interactions are suppressed in the nd -system, despite the non-perturbative renormalisation of parity-conserving 3-nucleon interactions. Therefore, few-nucleon experiments can dis-entangle PV 2-nucleon interactions at the 10%-level without introducing new unknowns. Supported in part by the US National Science Foundation under CAREER award PHY- 0645498, by the US Department of Energy under contract DE-FG02-95ER-40907, and by University Facilitating Funds of the George Washington University.

  6. Dynamic Localization of Electronic Excitation in Photosynthetic Complexes Revealed with Chiral Two-Dimensional Spectroscopy

    PubMed Central

    Fidler, Andrew F.; Singh, Ved P.; Long, Phillip D.; Dahlberg, Peter D.; Engel, Gregory S.

    2014-01-01

    Time-resolved ultrafast optical probes of chiral dynamics provide a new window allowing us to explore how interactions with such structured environments drive electronic dynamics. Incorporating optical activity into time-resolved spectroscopies has proven challenging due to the small signal and large achiral background. Here, we demonstrate that two-dimensional electronic spectroscopy can be adapted to detect chiral signals and that these signals reveal how excitations delocalize and contract following excitation. We dynamically probe the evolution of chiral electronic structure in the light harvesting complex 2 of purple bacteria following photoexcitation by creating a chiral two-dimensional mapping. The dynamics of the chiral two-dimensional signal directly reports on changes in the degree of delocalization of the excitonic state following photoexcitation. The mechanism of energy transfer in this system may enhance transfer probability due to the coherent coupling among chromophores while suppressing fluorescence that arises from populating delocalized states. This generally applicable spectroscopy will provide an incisive tool to probe ultrafast transient molecular fluctuations that are obscured in non-chiral experiments. PMID:24504144

  7. Advances in enantioselective analysis of chiral brominated flame retardants. Current status, limitations and future perspectives.

    PubMed

    Badea, Silviu-Laurentiu; Niculescu, Violeta Carolina; Ionete, Roxana-Elena; Eljarrat, Ethel

    2016-10-01

    Enantioselective analysis is a powerful tool for the discrimination of biotic and abiotic transformation processes of chiral environmental contaminants because their environmental biodegradation is mostly stereospecific. However, it is challenging when applied to new contaminants since enantioselective analysis methods are currently available only for a limited number of compounds. The enantioselective analysis of chiral novel brominated flame retardants (NBFRs) either using gas chromatography (GC) or liquid chromatography (LC) with various chiral stationary phases (CSP) coupled with various mass spectrometric techniques was extensively discussed. The elution order of hexabromocyclododecane (HBCD) enantiomers in chiral LC was reviewed using the experimental LC data combined also with predictions from a multi-mode Hamiltonian dynamics simulation model based on interaction energies of HBCD enantiomers with β-permethylated cyclodextrin. The further development of analytical methodologies for new chiral BFRs using advanced hyphenated analytical techniques, but also the next generation mass spectrometer analyzers (i.e. GC-Qrbitrap MS-MS, LC-Qrbitrap MS-MS), will contribute to a better characterization of the transformation pathways of chiral BFRs.

  8. Dynamic localization of electronic excitation in photosynthetic complexes revealed with chiral two-dimensional spectroscopy.

    PubMed

    Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

    2014-01-01

    Time-resolved ultrafast optical probes of chiral dynamics provide a new window allowing us to explore how interactions with such structured environments drive electronic dynamics. Incorporating optical activity into time-resolved spectroscopies has proven challenging because of the small signal and large achiral background. Here we demonstrate that two-dimensional electronic spectroscopy can be adapted to detect chiral signals and that these signals reveal how excitations delocalize and contract following excitation. We dynamically probe the evolution of chiral electronic structure in the light-harvesting complex 2 of purple bacteria following photoexcitation by creating a chiral two-dimensional mapping. The dynamics of the chiral two-dimensional signal directly reports on changes in the degree of delocalization of the excitonic states following photoexcitation. The mechanism of energy transfer in this system may enhance transfer probability because of the coherent coupling among chromophores while suppressing fluorescence that arises from populating delocalized states. This generally applicable spectroscopy will provide an incisive tool to probe ultrafast transient molecular fluctuations that are obscured in non-chiral experiments. PMID:24504144

  9. Advances in enantioselective analysis of chiral brominated flame retardants. Current status, limitations and future perspectives.

    PubMed

    Badea, Silviu-Laurentiu; Niculescu, Violeta Carolina; Ionete, Roxana-Elena; Eljarrat, Ethel

    2016-10-01

    Enantioselective analysis is a powerful tool for the discrimination of biotic and abiotic transformation processes of chiral environmental contaminants because their environmental biodegradation is mostly stereospecific. However, it is challenging when applied to new contaminants since enantioselective analysis methods are currently available only for a limited number of compounds. The enantioselective analysis of chiral novel brominated flame retardants (NBFRs) either using gas chromatography (GC) or liquid chromatography (LC) with various chiral stationary phases (CSP) coupled with various mass spectrometric techniques was extensively discussed. The elution order of hexabromocyclododecane (HBCD) enantiomers in chiral LC was reviewed using the experimental LC data combined also with predictions from a multi-mode Hamiltonian dynamics simulation model based on interaction energies of HBCD enantiomers with β-permethylated cyclodextrin. The further development of analytical methodologies for new chiral BFRs using advanced hyphenated analytical techniques, but also the next generation mass spectrometer analyzers (i.e. GC-Qrbitrap MS-MS, LC-Qrbitrap MS-MS), will contribute to a better characterization of the transformation pathways of chiral BFRs. PMID:27265736

  10. Alpha-clustered hypernuclei and chiral SU(3) dynamics

    NASA Astrophysics Data System (ADS)

    Hiyama, Emiko; Funaki, Yasuro; Kaiser, Norbert; Weise, Wolfram

    2014-01-01

    Selected light hypernuclei are studied using an α cluster model approach (the Hyper-THSR wave function) in combination with a density-dependent Λ hyperon-nuclear interaction derived from chiral SU(3) effective field theory. This interaction includes important two-pion exchange processes involving Σ N intermediate states and associated three-body mechanisms as well as effective mass and surface terms arising in a derivative expansion of the in-medium Λ self-energy. Applications and calculated results are presented and discussed for ^{13}_{Λ }C and _{Λ }^9Be. The lightest α clustered hypernucleus, ^5_{Λ }He, is also discussed in this context.

  11. Entanglement between the Deconfinement and the Chiral Symmetry Restoration

    SciTech Connect

    Sakai, Yuji; Sasaki, Takahiro; Yahiro, Masanobu; Kouno, Hiroaki

    2011-10-21

    We extend the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model by introducing an effective four-quark vertex depending on the Polyakov loop. The effective vertex generates entanglement interactions between the Polyakov loop and the chiral condensate. The new model is consistent with lattice QCD data at imaginary quark-number chemical potential and real and imaginary isospin chemical potentials. We investigate the influence of the entanglement interactions on the location of the critical endpoint at real quark-number chemical potential.

  12. Evaluation of Dalbavancin as chiral selector for HPLC and comparison with Teicoplanin based chiral stationary phases

    PubMed Central

    ZHANG, XIAOTONG; BAO, YE; HUANG, KE; BARNETT-RUNDLETT, KIMBER L.; ARMSTRONG, DANIEL W.

    2015-01-01

    Dalbavancin is a new compound of the macrocyclic glycopeptide family. It was covalently linked to 5μm silica particles by using two different binding chemsitries. Approximately two hundred and fifty racemates including (A) heterocyclic compounds; (B) chiral acids; (C) chiral amines; (D) chiral alcohols; (E) chiral sulfoxides and sulfilimines; (F) amino acids and amino acid derivatives; and (G) other chiral compounds were tested on the two new chiral stationary phases (CSP) using three different mobile phases. As dalbavancin is structurally related to teicoplanin, the same set of chiral compounds was screened on two commercially available teicoplanin CSPs for comparison. The dalbavancin CSPs were able to separate some enantiomers that were not separated by the teicoplanin CSPs and also showed improved separations for many racemates. However, there were other compounds only separated or better separated on teicoplanin CSPS. Therefore, the dalbavancin CSPs are complementary to the teicoplanin CSPs. PMID:19676111

  13. Unified Dark Matter and Dark Energy Description in a Chiral Cosmological Model

    NASA Astrophysics Data System (ADS)

    Abbyazov, Renat R.; Chervon, Sergey V.

    2013-03-01

    We show the way of dark matter and dark energy presentation via ansatzs on the kinetic energies of the fields in the two-component chiral cosmological model (CCM). To connect a kinetic interaction of dark matter and dark energy with observational data the reconstruction procedure for the chiral metric component h22 and the potential of (self-)interaction V has been developed. The reconstruction of h22 and V for the early and later inflation have been performed. The proposed model is confronted to ΛCDM model as well.

  14. Neutron matter with Quantum Monte Carlo: chiral 3N forces and static response

    DOE PAGES

    Buraczynski, M.; Gandolfi, S.; Gezerlis, A.; Schwenk, A.; Tews, I.

    2016-03-01

    Neutron matter is related to the physics of neutron stars and that of neutron-rich nuclei. Moreover, Quantum Monte Carlo (QMC) methods offer a unique way of solving the many-body problem non-perturbatively, providing feedback on features of nuclear interactions and addressing scenarios that are inaccessible to other approaches. Our contribution goes over two recent accomplishments in the theory of neutron matter: a) the fusing of QMC with chiral effective field theory interactions, focusing on local chiral 3N forces, and b) the first attempt to find an ab initio solution to the problem of static response.

  15. Chiral hypervalent iodine reagents: synthesis and reactivity.

    PubMed

    Parra, Alejandro; Reboredo, Silvia

    2013-12-16

    Chiral hypervalent iodine chemistry has been steadily increasing in importance in recent years. This review catalogues enantioselective transformations triggered by chiral hypervalent iodine(III/V) reagents, in stoichiometric or catalytic quantities, highlighting the different reactivities in terms of yield and enantioselectivity. Moreover, the synthesis of the most remarkable and successful catalysts has been illustrated in detail.

  16. Color Confinement and Dynamical Chiral Symmetry Breaking

    NASA Astrophysics Data System (ADS)

    Nakamura, Naoki; Suzuki, Tsuneo

    We study the relation between the quark confinement and the dynamical chiral symmetry breaking in SU(2) QCD by deriving an effective Lagrangian of a monopole field and the chiral fields from the dual Ginzburg-Landau type Lagrangian(DGL Lagrangian)…

  17. Quantization of the chiral soliton in medium

    NASA Astrophysics Data System (ADS)

    Nagai, S.; Sawado, N.; Shiiki, N.

    2006-01-01

    Chiral solitons coupled with quarks in medium are studied based on the Wigner-Seitz approximation. The chiral quark soliton model is used to obtain the classical soliton solutions. To investigate nucleon and Δ in matter, the semi-classical quantization is performed by the cranking method. The saturation for nucleon matter and Δ matter are observed.

  18. Generalized electromagnetic fields in a chiral medium

    NASA Astrophysics Data System (ADS)

    Bisht, P. S.; Singh, Jivan; Negi, O. P. S.

    2007-09-01

    The time-dependent Dirac-Maxwell's equations in the presence of electric and magnetic sources are reformulated in a chiral medium, and the solutions for the classical problem are obtained in a unique, simple and consistent manner. The quaternion reformulation of generalized electromagnetic fields in the chiral medium has also been discussed in a compact, simple and consistent manner.

  19. Chiral gravity, log gravity, and extremal CFT

    SciTech Connect

    Maloney, Alexander; Song Wei; Strominger, Andrew

    2010-03-15

    We show that the linearization of all exact solutions of classical chiral gravity around the AdS{sub 3} vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

  20. A lattice formulation of chiral gauge theories

    SciTech Connect

    Bodwin, G.T.

    1996-08-01

    We present a method for implementing gauge theories of chiral fermions on the lattice. Discussed topics include: the lattice as a UV regulator, a chiral QED model, modification of the fermion determinant, large gauge-field momenta, and a non-perturbative problem.

  1. Orientation-Dependent Handedness and Chiral Design

    NASA Astrophysics Data System (ADS)

    Efrati, Efi; Irvine, William T. M.

    2014-01-01

    Chirality occupies a central role in fields ranging from biological self-assembly to the design of optical metamaterials. The definition of chirality, as given by Lord Kelvin, associates chirality with the lack of mirror symmetry: the inability to superpose an object on its mirror image. While this definition has guided the classification of chiral objects for over a century, the quantification of handed phenomena based on this definition has proven elusive, if not impossible, as manifest in the paradox of chiral connectedness. In this work, we put forward a quantification scheme in which the handedness of an object depends on the direction in which it is viewed. While consistent with familiar chiral notions, such as the right-hand rule, this framework allows objects to be simultaneously right and left handed. We demonstrate this orientation dependence in three different systems—a biomimetic elastic bilayer, a chiral propeller, and optical metamaterial—and find quantitative agreement with chirality pseudotensors whose form we explicitly compute. The use of this approach resolves the existing paradoxes and naturally enables the design of handed metamaterials from symmetry principles.

  2. The phi-meson and Chiral-mass-meson production in heavy-ion collisions as potential probes of quark-gluon-plasma and Chiral symmetry transitions

    NASA Technical Reports Server (NTRS)

    Takahashi, Y.; Eby, P. B.

    1985-01-01

    Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.

  3. Chiral THz metamaterial with tunable optical activity

    SciTech Connect

    Zhou, Jiangfeng; Taylor, Antoinette; O' Hara, John; Chowdhury, Roy; Zhao, Rongkuo; Soukoullis, Costas M

    2010-01-01

    Optical activity in chiral metamaterials is demonstrated in simulation and shows actively tunable giant polarization rotation at THz frequencies. Electric current distributions show that pure chirality is achieved by our bi-Iayer chiral metamaterial design. The chirality can be optically controlled by illumination with near-infrared light. Optical activity, occurring in chiral materials such as DNA, sugar and many other bio-molecules, is a phenomenon of great importance to many areas of science including molecular biology, analytical chemistry, optoelectronics and display applications. This phenomenon is well understood at an effective medium level as a magnetic/electric moment excited by the electric/magnetic field of the incident electromagnetic (EM) wave. Usually, natural chiral materials exhibit very weak optical activity e.g. a gyrotropic quartz crystal. The optical activity of chiral metamaterials, however, can be five orders of magnitude stronger. Chiral metamaterials are made of sub-wavelength resonators lacking symmetry planes. The asymmetry allows magnetic moments to be excited by the electric field of the incident EM wave and vice versa. Recently, chiral metamaterials have been demonstrated and lead to prospects in giant optical activity, circular dichroism, negative refraction and reversing the Casmir force. These fascinating optical properties require strong chirality, which may be designed through the microscopic structure of chiral metamaterials. However, these metamaterials have a fixed response function, defined by the geometric structuring, which limits their ability to manipulate EM waves. Active metamaterials realize dynamic control of response functions and have produced many influential applications such as ultra-fast switching devices, frequency and phase modulation and memory devices. Introducing active designs to chiral metamaterials will give additional freedom in controlling the optical activity, and therefore enable dynamic manipulation

  4. Effective field theory in the harmonic oscillator basis

    DOE PAGES

    Binder, S.; Ekström, Jan A.; Hagen, Gaute; Papenbrock, Thomas F.; Wendt, Kyle A.

    2016-04-25

    In this paper, we develop interactions from chiral effective field theory (EFT) that are tailored to the harmonic oscillator basis. As a consequence, ultraviolet convergence with respect to the model space is implemented by construction and infrared convergence can be achieved by enlarging the model space for the kinetic energy. In oscillator EFT, matrix elements of EFTs formulated for continuous momenta are evaluated at the discrete momenta that stem from the diagonalization of the kinetic energy in the finite oscillator space. By fitting to realistic phase shifts and deuteron data we construct an effective interaction from chiral EFT at next-to-leadingmore » order. Finally, many-body coupled-cluster calculations of nuclei up to 132Sn converge fast for the ground-state energies and radii in feasible model spaces.« less

  5. Light chiral dark sector

    NASA Astrophysics Data System (ADS)

    Harigaya, Keisuke; Nomura, Yasunori

    2016-08-01

    An interesting possibility for dark matter is a scalar particle of mass of order 10 MeV-1 GeV, interacting with a U (1 ) gauge boson (dark photon) which mixes with the photon. We present a simple and natural model realizing this possibility. The dark matter arises as a composite pseudo-Nambu-Goldstone boson (dark pion) in a non-Abelian gauge sector, which also gives a mass to the dark photon. For a fixed non-Abelian gauge group, S U (N ) , and a U (1 ) charge of the constituent dark quarks, the model has only three free parameters: the dynamical scale of the non-Abelian gauge theory, the gauge coupling of the dark photon, and the mixing parameter between the dark and standard model photons. In particular, the gauge symmetry of the model does not allow any mass term for the dark quarks, and the stability of the dark pion is understood as a result of an accidental global symmetry. The model has a significant parameter space in which thermal relic dark pions comprise all of the dark matter, consistently with all experimental and cosmological constraints. In a corner of the parameter space, the discrepancy of the muon g -2 between experiments and the standard model prediction can also be ameliorated due to a loop contribution of the dark photon. Smoking-gun signatures of the model include a monophoton signal from the e+e- collision into a photon and a "dark rho meson." Observation of two processes in e+e- collision—the mode into the dark photon and that into the dark rho meson—would provide strong evidence for the model.

  6. Tunable lithography masks using chiral nematic fluids

    NASA Astrophysics Data System (ADS)

    Jeong, Hyeon Su; Srinivasarao, Mohan; Jung, Hee-Tae

    2013-03-01

    We present a facile route for pattern formation using chiral nematic fluids as tunable masks in lithography process. The chiral nematic phase prepared by adding a chiral dopant (CB15) to 5CB acted as a set of parallel cylindrical lenses and as a polarization selective photomask for the preparation of periodic line patterns. The pitch of the helical twist was easily controlled by the concentration of chiral agent and the feature size of the resulting pattern was easily tuned. Because of the high mobility of the small liquid crystalline compound, the preparation of chiral nematic fluids based lithography masks requires only a few seconds. This approach has significant advantages including facility, range of surface ordering, and rate of forming periodic arrays. Current affiliation: SK Innovation, Daejeon, Korea

  7. Enantioselective environmental toxicology of chiral pesticides.

    PubMed

    Ye, Jing; Zhao, Meirong; Niu, Lili; Liu, Weiping

    2015-03-16

    The enantioselective environmental toxic effect of chiral pesticides is becoming more important. As the industry develops, increasing numbers of chiral insecticides and herbicides will be introduced into use, potentially posing toxic effects on nontarget living beings. Chiral pesticides, including herbicides such as acylanilides, phenoxypropanoic acids, and imidazolinones, and insecticides such as synthetic pyrethroids, organophosphates, and DDT often behave enantioselectively during agricultural use. These compounds also pose unpredictable enantioselective ecological threats to nontarget living beings and/or humans, affecting the food chain and entire ecosystems. Thus, to investigate the enantioselective toxic effects of chiral insecticides and herbicides is necessary during environmental protection. The environmental toxicology of chiral pesticides, especially the findings obtained from studies conducted in our laboratory during the past 10 years, is reviewed. PMID:25643169

  8. Chiral magnetic effect in condensed matter systems

    DOE PAGES

    Li, Qiang; Kharzeev, Dmitri E.

    2016-12-01

    The chiral magnetic effect is the generation of electrical current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum anomaly in relativistic field theory of chiral fermions. In the quark-gluon plasma, the axial anomaly induces topological charge changing transition that results in the generation of electrical current along the magnetic field. In condensed matter systems, the chiral magnetic effect was first predicted in the gapless semiconductors with tow energy bands having pointlike degeneracies. In addition, thirty years later after this prediction, the chiral magnetic effect was finally observed in the 3Dmore » Dirac/Weyl semimetals.« less

  9. A liquid crystalline chirality balance for vapours

    NASA Astrophysics Data System (ADS)

    Ohzono, Takuya; Yamamoto, Takahiro; Fukuda, Jun-Ichi

    2014-04-01

    Chiral discrimination of vapours plays an important role in olfactory perception of biological systems and its realization by artificial sensors has been an intriguing challenge. Here, we report a simple method that tangibly visualizes the chirality of a diverse variety of molecules dissolved from vapours with high sensitivity, by making use of a structural change in a periodic microstructure of a nematic liquid crystal confined in open microchannels. This microstructure is accompanied by a topological line defect of a zigzag form with equal lengths of ‘zig’ and ‘zag.’ We find that a tiny amount of vapour of chiral molecules injected onto the liquid crystal induces the imbalance of ‘zig’ and ‘zag’ depending on its enantiomeric excess within a few seconds. Our liquid-crystal-based ‘chirality balance’ offers a simple, quick and versatile chirality-sensing/-screening method for gas-phase analysis (for example, for odours, environmental chemicals or drugs).

  10. Axially chiral allenyl gold complexes.

    PubMed

    Johnson, Alice; Laguna, Antonio; Gimeno, M Concepción

    2014-09-17

    Unprecedented allenyl gold complexes have been achieved starting from triphenylpropargylphosphonium bromide. Two different coordination modes of the allene isomer of triphenylphosphoniumpropargylide to gold have been found depending on the gold oxidation state. Bromo-, pentafluorophenyl-, and triphenylphosphine-gold(I) allenyl complexes were prepared in which the α carbon coordinates to the gold(I) center. A chiral pentafluorophenyl-gold(III) allenyl complex with the gold atoms coordinated to the γ carbon was also prepared. All the complexes have been structurally characterized by X-ray diffraction showing the characteristic distances for a C═C═C unit.

  11. Nuclear forces and chiral theories

    SciTech Connect

    Friar, J.L. |

    1995-09-01

    Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force will also be discussed in this context.

  12. Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor

    PubMed Central

    Martín-Rodríguez, María; de Cózar, Abel

    2011-01-01

    Summary The synthesis of a GSK 2nd generation inhibitor of the hepatitis C virus, by enantioselective 1,3-dipolar cycloaddition between a leucine derived iminoester and tert-butyl acrylate, was studied. The comparison between silver(I) and gold(I) catalysts in this reaction was established by working with chiral phosphoramidites or with chiral BINAP. The best reaction conditions were used for the total synthesis of the hepatitis C virus inhibitor by a four step procedure affording this product in 99% ee and in 63% overall yield. The origin of the enantioselectivity of the chiral gold(I) catalyst was justified according to DFT calculations, the stabilizing coulombic interaction between the nitrogen atom of the thiazole moiety and one of the gold atoms being crucial. PMID:21915198

  13. 3D chiral nanoplasmonics: fabrication, chiroptic engineering, mechanism, and application in enantioselection (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Huang, Zhifeng

    2015-09-01

    Chirality does naturally exist, and the building blocks of life (e.g. DNA, proteins, peptides and sugars) are usually chiral. Chirality inherently imposes chemical/biological selectivity on functional molecules; hence the discrimination in molecular chirality from an enantiomer to the other mirror image (i.e. enantioselection) has fundamental and application significance. Enantiomers interact with left and right handed circularly polarized light in a different manner with respect to optical extinction; hence, electronic circular dichroism (ECD) has been widely used for enantioselection. However, enantiomers usually have remarkably low ECD intensity, mainly owing to the small electric transition dipole moment induced by molecular sizes compared to the ECD-active wavelength in the UV-visible-near IR region. To enhance ECD magnitude, recently it has being developed 3D chiral nanoplasmonic structures having a helical path, and the dimensions are comparable to the ECD wavelength. However, it is still ambiguous the origin of 3D chiroplasmonics, and there is a lack of studying the interaction of 3D chiroplasmoncs with enantiomers for the application of enantioselection. Herein, we will present a one-step fabrication of 3D silver nanospirals (AgNSs) via low-substrate-temperature glancing angle deposition. AgNSs can be deposited on a wide range of substrates (including transparent and flexible substrates), in an area on the order of cm2. A set of spiral dimensions (such as spiral pitches, number of turns and handedness) have been easily engineered to tune the chiroptic properties, leading to studying the chiroplasmonic principles together with finite element simulation and the LC model. At the end, it will be demonstrated that 3D chiroplasmonics can differentiate molecular chirality of enantiomers with dramatic enhancement in the anisotropy g factor. This study opens a door to sensitively discriminate enantiomer chirality.

  14. Solvent-induced helical assembly and reversible chiroptical switching of chiral cyclic-dipeptide-functionalized naphthalenediimides.

    PubMed

    Manchineella, Shivaprasad; Prathyusha, V; Priyakumar, U Deva; Govindaraju, T

    2013-12-01

    Understanding the roles of various parameters in orchestrating the preferential chiral molecular organization in supramolecular self-assembly processes is of great significance in designing novel molecular functional systems. Cyclic dipeptide (CDP) chiral auxiliary-functionalized naphthalenediimides (NCDPs 1-6) have been prepared and their chiral self-assembly properties have been investigated. Detailed photophysical and circular dichroism (CD) studies have unveiled the crucial role of the solvent in the chiral aggregation of these NCDPs. NCDPs 1-3 form supramolecular helical assemblies and exhibit remarkable chiroptical switching behaviour (M- to P-type) depending on the solvent composition of HFIP and DMSO. The strong influence of solvent composition on the supramolecular chirality of NCDPs has been further corroborated by concentration and solid-state thin-film CD studies. The chiroptical switching between supramolecular aggregates of opposite helicity (M and P) has been found to be reversible, and can be achieved through cycles of solvent removal and redissolution in solvent mixtures of specific composition. The control molecular systems (NCDPs 4-6), with an achiral or D-isomer second amino acid in the CDP auxiliary, did not show chiral aggregation properties. The substantial roles of hydrogen bonding and π-π interactions in the assembly of the NCDPs have been validated through nuclear magnetic resonance (NMR), photophysical, and computational studies. Quantum chemical calculations at the ab initio, semiempirical, and density functional theory levels have been performed on model systems to understand the stabilities of the right (P-) and left (M-) handed helical supramolecular assemblies and the nature of the intermolecular interactions. This study emphasizes the role of CDP chiral auxiliaries on the solvent-induced helical assembly and reversible chiroptical switching of naphthalenediimides. PMID:24281809

  15. Synthesis, π-face-selective aggregation, and π-face chiral recognition of configurationally stable C(3)-symmetric propeller-chiral molecules with a π-core.

    PubMed

    Saito, Nozomi; Terakawa, Ryo; Yamaguchi, Masahiko

    2014-05-01

    The C3 -symmetric propeller-chiral compounds (P,P,P)-1 and (M,M,M)-1 with planar π-cores perpendicular to the C3 -axis were synthesized in optically pure states. (P,P,P)-1 possesses two distinguishable propeller-chiral π-faces with rims of different heights named the (P/L)-face and (P/H)-face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π-core. (P,P,P)-1 formed dimeric aggregates in organic solutions as indicated by the results of (1) H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The (P/L)/(P/L) interactions were observed in the solid state by single-crystal X-ray analysis, and they were also predominant over the (P/H)/(P/H) and (P/L)/(P/H) interactions in solution, as indicated by the results of (1) H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral (P,P,P)-1/(M,M,M)-1 interactions were much weaker than the homochiral (P,P,P)-1/(P,P,P)-1 interactions. The results indicated that the propeller-chiral (P/L)-face interacts with the (P/L)-face more strongly than with the (P/H)-face, (M/L)-face, and (M/H)-face. The study showed the π-face-selective aggregation and π-face chiral recognition of the configurationally stable propeller-chiral molecules.

  16. Biomimetic Hierarchical Assembly of Helical Supraparticles from Chiral Nanoparticles.

    PubMed

    Zhou, Yunlong; Marson, Ryan L; van Anders, Greg; Zhu, Jian; Ma, Guanxiang; Ercius, Peter; Sun, Kai; Yeom, Bongjun; Glotzer, Sharon C; Kotov, Nicholas A

    2016-03-22

    Chiroptical materials found in butterflies, beetles, stomatopod crustaceans, and other creatures are attributed to biocomposites with helical motifs and multiscale hierarchical organization. These structurally sophisticated materials self-assemble from primitive nanoscale building blocks, a process that is simpler and more energy efficient than many top-down methods currently used to produce similarly sized three-dimensional materials. Here, we report that molecular-scale chirality of a CdTe nanoparticle surface can be translated to nanoscale helical assemblies, leading to chiroptical activity in the visible electromagnetic range. Chiral CdTe nanoparticles coated with cysteine self-organize around Te cores to produce helical supraparticles. D-/L-Form of the amino acid determines the dominant left/right helicity of the supraparticles. Coarse-grained molecular dynamics simulations with a helical pair-potential confirm the assembly mechanism and the origin of its enantioselectivity, providing a framework for engineering three-dimensional chiral materials by self-assembly. The helical supraparticles further self-organize into lamellar crystals with liquid crystalline order, demonstrating the possibility of hierarchical organization and with multiple structural motifs and length scales determined by molecular-scale asymmetry of nanoparticle interactions.

  17. Chiral Bosonic Mott Insulator on the Frustrated Triangular Lattice

    NASA Astrophysics Data System (ADS)

    Parameswaran, Siddharth; Zaletel, Michael; Rüegg, Andreas; Altman, Ehud

    2014-03-01

    We study the superfluid and insulating phases of interacting bosons on the triangular lattice with an inverted dispersion, corresponding to frustrated hopping between sites. The resulting single-particle dispersion has multiple minima at nonzero wavevectors in momentum space, in contrast to the unique zero-wavevector minimum of the unfrustrated problem. As a consequence, the superfluid phase is unstable against developing additional chiral order that breaks time reversal (T) and parity (P) symmetries by forming a condensate at nonzero wavevector. We demonstrate that the loss of superfluidity can lead to an even more exotic phase, the chiral Mott insulator, with nontrivial current order that breaks T, P. These results are obtained via variational estimates, as well as a combination of bosonization and DMRG of triangular ladders, which taken together permit a fairly complete characterization of the phase diagram. We discuss the relevance of these phases to optical lattice experiments, as well as signatures of chiral symmetry breaking in time-of-flight images. We acknowledge support from NSF Grants 1066293 (SP, EA) and DGE-1106400 (MPZ), the Simons Foundation (SP), the Swiss National Science Foundation (AR), the ISF, BSF, ERC Synergy UQUAM program and the Miller Institute at UC Berkeley (EA).

  18. Chiral bosonic Mott insulator on the frustrated triangular lattice

    NASA Astrophysics Data System (ADS)

    Zaletel, Michael P.; Parameswaran, S. A.; Rüegg, Andreas; Altman, Ehud

    2014-04-01

    We study the superfluid and insulating phases of interacting bosons on the triangular lattice with an inverted dispersion, corresponding to frustrated hopping between sites. The resulting single-particle dispersion has multiple minima at nonzero wave vectors in momentum space, in contrast to the unique zero-wave-vector minimum of the unfrustrated problem. As a consequence, the superfluid phase is unstable against developing additional chiral order that breaks time-reversal (T) and parity (P) symmetries by forming a condensate at nonzero wave vector. We demonstrate that the loss of superfluidity can lead to an even more exotic phase, the chiral Mott insulator, with nontrivial current order that breaks T ,P. These results are obtained via variational estimates, as well as a combination of bosonization and density-matrix renormalization group of triangular ladders, which, taken together, permit a fairly complete characterization of the phase diagram. We discuss the relevance of these phases to optical lattice experiments, as well as signatures of chiral symmetry breaking in time-of-flight images.

  19. Molecular dynamics simulation and NMR investigation of the association of the β-blockers atenolol and propranolol with a chiral molecular micelle

    NASA Astrophysics Data System (ADS)

    Morris, Kevin F.; Billiot, Eugene J.; Billiot, Fereshteh H.; Hoffman, Charlene B.; Gladis, Ashley A.; Lipkowitz, Kenny B.; Southerland, William M.; Fang, Yayin

    2015-08-01

    Molecular dynamics simulations and NMR spectroscopy were used to compare the binding of two β-blocker drugs to the chiral molecular micelle poly-(sodium undecyl-(L)-leucine-valine). The molecular micelle is used as a chiral selector in capillary electrophoresis. This study is part of a larger effort to understand the mechanism of chiral recognition in capillary electrophoresis by characterizing the molecular micelle binding of chiral compounds with different geometries and charges. Propranolol and atenolol were chosen because their structures are similar, but their chiral interactions with the molecular micelle are different. Molecular dynamics simulations showed both propranolol enantiomers inserted their aromatic rings into the molecular micelle core and that (S)-propranolol associated more strongly with the molecular micelle than (R)-propranolol. This difference was attributed to stronger molecular micelle hydrogen bonding interactions experienced by (S)-propranolol. Atenolol enantiomers were found to bind near the molecular micelle surface and to have similar molecular micelle binding free energies.

  20. Static and dynamic effects of chirality in dielectric media

    NASA Astrophysics Data System (ADS)

    Lakes, R. S.

    2016-09-01

    Chiral dielectrics are considered from the perspective of continuum representations of spatial heterogeneity. Static effects in isotropic chiral dielectrics are predicted, provided the electric field has nonzero third spatial derivatives. The effects are compared with static chiral phenomena in Cosserat elastic materials which obey generalized continuum constitutive equations. Dynamic monopole-like magnetic induction is predicted in chiral dielectric media.

  1. Big, strong, neutral, twisted, and chiral π acids.

    PubMed

    Zhao, Yingjie; Huang, Guangxi; Besnard, Celine; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2015-04-13

    General synthetic access to expanded π-acidic surfaces of variable size, topology, chirality, and π acidity is reported. The availability of π surfaces with these characteristics is essential to develop the functional relevance of anion-π interactions with regard to molecular recognition, translocation, and transformation. The problem is that, with expanded π surfaces, the impact of electron-withdrawing substituents decreases and the high π acidity needed for strong anion-π interactions can be more difficult to obtain. To overcome this problem, it is herein proposed to build large surfaces from smaller fragments and connect these fragments with bridges that are composed only of single atoms. Two central surfaces for powerful anion-π interactions, namely, perfluoroarenes and naphthalenediimides (NDIs), were selected as fragments and coupled with through sulfide bridges. Their oxidation to sulfoxides and sulfones, as well as fluorine substitution in the peripheral rings, provides access to the full chemical space of relevant π acidities. According to cyclic voltammetry, LUMO levels range from -3.96 to -4.72 eV. With sulfoxide bridges, stereogenic centers are introduced to further enrich the intrinsic planar chirality of the expanded surfaces. The stereoisomers were separated by chiral HPLC and characterized by X-ray crystallography. Their topologies range from chairs to π boats, and the latter are reminiscent of the cation-π boxes in operational neuronal receptors. With pentafluorophenyl acceptors, the π acidity of NDIs with two sulfoxide groups in the core reaches -4.45 eV, whereas two sulfone moieties give a value of -4.72 eV, which is as low as with four ethyl sulfone groups, that is, a π superacid near the limit of existence. Beyond anion-π interactions, these conceptually innovative π-acidic surfaces are also of interest as electron transporters in conductive materials.

  2. A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER).

    PubMed

    Garbacz, Piotr; Fischer, Peer; Krämer, Steffen

    2016-09-14

    Direct detection of molecular chirality is practically impossible by methods of standard nuclear magnetic resonance (NMR) that is based on interactions involving magnetic-dipole and magnetic-field operators. However, theoretical studies provide a possible direct probe of chirality by exploiting an enantiomer selective additional coupling involving magnetic-dipole, magnetic-field, and electric field operators. This offers a way for direct experimental detection of chirality by nuclear magneto-electric resonance (NMER). This method uses both resonant magnetic and electric radiofrequency (RF) fields. The weakness of the chiral interaction though requires a large electric RF field and a small transverse RF magnetic field over the sample volume, which is a non-trivial constraint. In this study, we present a detailed study of the NMER concept and a possible experimental realization based on a loop-gap resonator. For this original device, the basic principle and numerical studies as well as fabrication and measurements of the frequency dependence of the scattering parameter are reported. By simulating the NMER spin dynamics for our device and taking the (19)F NMER signal of enantiomer-pure 1,1,1-trifluoropropan-2-ol, we predict a chirality induced NMER signal that accounts for 1%-5% of the standard achiral NMR signal. PMID:27634253

  3. Magnetochiral nonreciprocity of volume spin wave propagation in chiral-lattice ferromagnets

    NASA Astrophysics Data System (ADS)

    Seki, S.; Okamura, Y.; Kondou, K.; Shibata, K.; Kubota, M.; Takagi, R.; Kagawa, F.; Kawasaki, M.; Tatara, G.; Otani, Y.; Tokura, Y.

    2016-06-01

    In magnetic materials with chiral crystal structure, it has been predicted that quasiparticle flows propagating parallel and antiparallel to the external magnetic field can show different propagating character, with its sign of nonreciprocity dependent on the chirality of the underlying bulk crystal lattice. This unique phenomenon, termed magnetochiral nonreciprocity, has previously been demonstrated for the propagating light and conduction electrons but seldom for other quasiparticles. In this study, we report the experimental observation of magnetochiral nonreciprocity of propagating magnons for a chiral-lattice ferromagnet Cu2OSeO3 by employing the spin wave spectroscopy. We found that the sign of nonreciprocity is reversed for the opposite chirality of crystal, and also directly identified the wave-number-linear term in the spin wave dispersion associated with the Dzyaloshinskii-Moriya (DM) interaction as the origin of observed nonreciprocity. Our present results pave a route for the design of efficient spin wave diode based on the bulk crystallographic symmetry breaking and also offer a unique method to evaluate the magnitude of DM interaction in chiral-lattice bulk compounds.

  4. A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER)

    NASA Astrophysics Data System (ADS)

    Garbacz, Piotr; Fischer, Peer; Krämer, Steffen

    2016-09-01

    Direct detection of molecular chirality is practically impossible by methods of standard nuclear magnetic resonance (NMR) that is based on interactions involving magnetic-dipole and magnetic-field operators. However, theoretical studies provide a possible direct probe of chirality by exploiting an enantiomer selective additional coupling involving magnetic-dipole, magnetic-field, and electric field operators. This offers a way for direct experimental detection of chirality by nuclear magneto-electric resonance (NMER). This method uses both resonant magnetic and electric radiofrequency (RF) fields. The weakness of the chiral interaction though requires a large electric RF field and a small transverse RF magnetic field over the sample volume, which is a non-trivial constraint. In this study, we present a detailed study of the NMER concept and a possible experimental realization based on a loop-gap resonator. For this original device, the basic principle and numerical studies as well as fabrication and measurements of the frequency dependence of the scattering parameter are reported. By simulating the NMER spin dynamics for our device and taking the 19F NMER signal of enantiomer-pure 1,1,1-trifluoropropan-2-ol, we predict a chirality induced NMER signal that accounts for 1%-5% of the standard achiral NMR signal.

  5. Multipolar Effects in the Optical Active Second Harmonic Generation from Sawtooth Chiral Metamaterials

    PubMed Central

    Su, Huimin; Guo, Yuxiang; Gao, Wensheng; Ma, Jie; Zhong, Yongchun; Tam, Wing Yim; Chan, C. T.; Wong, Kam Sing

    2016-01-01

    Based on the facts that chiral molecules response differently to left- and right-handed circular polarized light, chiroptical effects are widely employed for determining structure chirality, detecting enantiomeric excess, or controlling chemical reactions of molecules. Compared to those in natural materials, chiroptical behaviors can be significantly amplified in chiral plasmonic metamaterials due to the concentrated local fields in the structure. The on-going research towards giant chiroptical effects in metamaterial generally focus on optimizing the field-enhancement effects. However, the observed chiroptical effects in metamaterials rely on more complicated factors and various possibilities towards giant chiroptical effects remains unexplored. Here we study the optical-active second harmonic generation (SHG) behaviors in a pair of planar sawtooth gratings with mirror-imaged patterns. Significant multipolar effects were observed in the polarization-dependent SHG curves. We show that the chirality of the nanostructure not only give rise to nonzero chiral susceptibility tensor components within the electric-dipole approximation, but also lead to different levels of multipolar interactions for the two orthogonal circular polarizations that further enhance the nonlinear optical activity of the material. Our results thus indicate novel ways to optimize nonlinear plasmonic structures and achieve giant chiroptical response via multipolar interactions. PMID:26911449

  6. Multipolar Effects in the Optical Active Second Harmonic Generation from Sawtooth Chiral Metamaterials.

    PubMed

    Su, Huimin; Guo, Yuxiang; Gao, Wensheng; Ma, Jie; Zhong, Yongchun; Tam, Wing Yim; Chan, C T; Wong, Kam Sing

    2016-02-25

    Based on the facts that chiral molecules response differently to left- and right-handed circular polarized light, chiroptical effects are widely employed for determining structure chirality, detecting enantiomeric excess, or controlling chemical reactions of molecules. Compared to those in natural materials, chiroptical behaviors can be significantly amplified in chiral plasmonic metamaterials due to the concentrated local fields in the structure. The on-going research towards giant chiroptical effects in metamaterial generally focus on optimizing the field-enhancement effects. However, the observed chiroptical effects in metamaterials rely on more complicated factors and various possibilities towards giant chiroptical effects remains unexplored. Here we study the optical-active second harmonic generation (SHG) behaviors in a pair of planar sawtooth gratings with mirror-imaged patterns. Significant multipolar effects were observed in the polarization-dependent SHG curves. We show that the chirality of the nanostructure not only give rise to nonzero chiral susceptibility tensor components within the electric-dipole approximation, but also lead to different levels of multipolar interactions for the two orthogonal circular polarizations that further enhance the nonlinear optical activity of the material. Our results thus indicate novel ways to optimize nonlinear plasmonic structures and achieve giant chiroptical response via multipolar interactions.

  7. Nucleic acids, proteins, and chirality

    NASA Technical Reports Server (NTRS)

    Usher, D. A.; Profy, A. T.; Walstrum, S. A.; Needels, M. C.; Bulack, S. C.; Lo, K. M.

    1984-01-01

    The present investigation is concerned with experimental results related, in one case, to the chirality of nucleotides, and, in another case, to the possibility of a link between the chirality of nucleic acids, and that of peptides. It has been found that aminoacylation of the 'internal' hydroxyl group of a dinucleoside monophosphate can occur stereoselectively. However, this reaction has not yet been made a part of a working peptide synthesis scheme. The formation and cleavage of oligonucleotides is considered. In the event of the formation of a helical complex between the oligonucleotide and the polymer, 1-prime,5-prime-bonds in the oligomer are found to become more resistant towards cleavage. The conditions required for peptide bond formation are examined, taking into account the known structures of RNA and possible mechanisms for prebiotic peptide bond formation. The possibility is considered that the 2-prime,5-prime-internucleotide linkage could have played an important part in the early days of biological peptide synthesis.

  8. Hierarchical chirality transfer in the growth of Towel Gourd tendrils

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

    2013-10-01

    Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties.

  9. Hierarchical chirality transfer in the growth of Towel Gourd tendrils.

    PubMed

    Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

    2013-01-01

    Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties. PMID:24173107

  10. Hierarchical chirality transfer in the growth of Towel Gourd tendrils

    PubMed Central

    Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

    2013-01-01

    Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties. PMID:24173107

  11. Spontaneous Planar Chiral Symmetry Breaking in Cells

    NASA Astrophysics Data System (ADS)

    Hadidjojo, Jeremy; Lubensky, David

    Recent progress in animal development has highlighted the central role played by planar cell polarity (PCP) in epithelial tissue morphogenesis. Through PCP, cells have the ability to collectively polarize in the plane of the epithelium by localizing morphogenetic proteins along a certain axis. This allows direction-dependent modulation of tissue mechanical properties that can translate into the formation of complex, non-rotationally invariant shapes. Recent experimental observations[1] show that cells, in addition to being planar-polarized, can also spontaneously develop planar chirality, perhaps in the effort of making yet more complex shapes that are reflection non-invariant. In this talk we will present our work in characterizing general mechanisms that can lead to spontaneous chiral symmetry breaking in cells. We decompose interfacial concentration of polarity proteins in a hexagonal cell packing into irreducible representations. We find that in the case of polar concentration distributions, a chiral state can only be reached from a secondary instability after the cells are polarized. However in the case of nematic distributions, we show that a finite-amplitude (subcritical, or ``first-order'') nematic transition can send the system from disorder directly to a chiral state. In addition, we find that perturbing the system by stretching the hexagonal packing enables direct (supercritical, or ``second-order'') chiral transition in the nematic case. Finally, we do a Landau expansion to study competition between stretch-induced chirality and the tendency towards a non-chiral state in packings that have retained the full 6-fold symmetry.

  12. Broken chiral symmetry on a null plane

    SciTech Connect

    Beane, Silas R.

    2013-10-15

    On a null-plane (light-front), all effects of spontaneous chiral symmetry breaking are contained in the three Hamiltonians (dynamical Poincaré generators), while the vacuum state is a chiral invariant. This property is used to give a general proof of Goldstone’s theorem on a null-plane. Focusing on null-plane QCD with N degenerate flavors of light quarks, the chiral-symmetry breaking Hamiltonians are obtained, and the role of vacuum condensates is clarified. In particular, the null-plane Gell-Mann–Oakes–Renner formula is derived, and a general prescription is given for mapping all chiral-symmetry breaking QCD condensates to chiral-symmetry conserving null-plane QCD condensates. The utility of the null-plane description lies in the operator algebra that mixes the null-plane Hamiltonians and the chiral symmetry charges. It is demonstrated that in a certain non-trivial limit, the null-plane operator algebra reduces to the symmetry group SU(2N) of the constituent quark model. -- Highlights: •A proof (the first) of Goldstone’s theorem on a null-plane is given. •The puzzle of chiral-symmetry breaking condensates on a null-plane is solved. •The emergence of spin-flavor symmetries in null-plane QCD is demonstrated.

  13. Chiral Alfvén Wave in Anomalous Hydrodynamics.

    PubMed

    Yamamoto, Naoki

    2015-10-01

    We study the hydrodynamic regime of chiral plasmas at high temperature. We find a new type of gapless collective excitation induced by chiral effects in an external magnetic field. This is a transverse wave, and it is present even in incompressible fluids, unlike the chiral magnetic and chiral vortical waves. The velocity is proportional to the coefficient of the gravitational anomaly. We briefly discuss the possible relevance of this "chiral Alfvén wave" in physical systems. PMID:26551804

  14. Elastic waves in structurally chiral composites

    SciTech Connect

    Yang, Shiuhkuang.

    1990-01-01

    Elastic wave propagation through structurally chiral (handed) media was studied. The primary objectives are to construct structurally chiral composites and to characterize their properties. Structurally chiral composites are constructed by stacking identical uniaxial plates, whose consecutive symmetric axes describe either a right- or a left-handed spiral. A matrix representation method is used to solve the elastic wave propagation in such layered composites. Numerical computation of the plane wave reflection and transmission characteristics for chiral arrangements are compared with those for the non-chiral one. It is concluded that the co-polarized characteristics are unaffected by the structural chirality, while the cross-polarized reflected and transmitted fields are greatly influenced by it. Numerical modeling is also applied for the real samples. The polarization ellipse of the transmitted field of each sample is calculated. To verify the form chirality, four glass-reinforced chiral and non-chiral composite samples are made from helix tape, molded, debulked, and cured individually under identical temperature and pressure histories. The spiral composites are characterized using shear and longitudinal wave transducers in ultrasonic experiments. Both the material properties and the polarization ellipse of the transmitted field of each sample are measured. It is proved conclusively that left and right handedness in the microstructures of a material rotates the plane of polarization of a propagating shear wave in the opposite directions. Thus it is now possible to say that by reducing the length scale of the handed microstructures tone more appropriate to its propagating wavelength, a medium is obtained that gives rise to effects similar to optical radar and optical dichroism.

  15. Extreme optical chirality of plasmonic nanohole arrays due to chiral Fano resonance

    NASA Astrophysics Data System (ADS)

    Kondratov, A. V.; Gorkunov, M. V.; Darinskii, A. N.; Gainutdinov, R. V.; Rogov, O. Y.; Ezhov, A. A.; Artemov, V. V.

    2016-05-01

    We study the physical origin of extreme optical chirality of subwavelength arrays of chiral holes in metal. We reconstruct the nanoscale relief of the hole arrays by the atomic-force microscopy and post-process the data to acquire an average unit-cell shape clear of noise and defects. For this shape, we perform the electromagnetic finite difference time domain simulations that reproduce all important features observed by the light-transmission experiments, including the notably strong circular dichroism and optical activity covering the whole range of possible values. To interpret the simulation results, we develop a chiral coupled-mode model which yields analytical expressions that fit accurately the numerical data in a broad wavelength range. Our conclusions undoubtedly link the extreme optical chirality to the plasmon resonances of chiral holes and the associated chiral Fano-type transmission resonance.

  16. Induced chirality through electromagnetic coupling between chiral molecular layers and plasmonic nanostructures.

    PubMed

    Abdulrahman, Nadia A; Fan, Z; Tonooka, Taishi; Kelly, Sharon M; Gadegaard, Nikolaj; Hendry, Euan; Govorov, Alexander O; Kadodwala, Malcolm

    2012-02-01

    We report a new approach for creating chiral plasmonic nanomaterials. A previously unconsidered, far-field mechanism is utilized which enables chirality to be conveyed from a surrounding chiral molecular material to a plasmonic resonance of an achiral metallic nanostructure. Our observations break a currently held preconception that optical properties of plasmonic particles can most effectively be manipulated by molecular materials through near-field effects. We show that far-field electromagnetic coupling between a localized plasmon of a nonchiral nanostructure and a surrounding chiral molecular layer can induce plasmonic chirality much more effectively (by a factor of 10(3)) than previously reported near-field phenomena. We gain insight into the mechanism by comparing our experimental results to a simple electromagnetic model which incorporates a plasmonic object coupled with a chiral molecular medium. Our work offers a new direction for the creation of hybrid molecular plasmonic nanomaterials that display significant chiroptical properties in the visible spectral region.

  17. Towards chirality-pure carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Yani; Zheng, Lianxi

    2010-10-01

    Current as-grown single-walled carbon nanotubes vary in diameter and chirality, which results in variations in their electronic and optical properties. Two approaches have been intensively studied to obtain chirality-pure nanotube structures and thus uniform properties for advanced applications. The first approach involves the post-synthesis separation according to the nanotubes' chiral vectors (n, m), and the second one involves direct synthes of carbon nanotubes with the same (n, m). This paper reviews the efforts along these two directions, with emphasis on the most recent progress of post-synthesis separation and the perspectives of controllable synthesis.

  18. Chiral Isotropic Liquids from Achiral Molecules

    SciTech Connect

    L Hough; M Spannuth; M Nakata; D Coleman; C Jones; G Dantlgraber; C Tschierske; J Watanabe; N Clark; et al.

    2011-12-31

    A variety of simple bent-core molecules exhibit smectic liquid crystal phases of planar fluid layers that are spontaneously both polar and chiral in the absence of crystalline order. We found that because of intralayer structural mismatch, such layers are also only marginally stable against spontaneous saddle splay deformation, which is incompatible with long-range order. This results in macroscopically isotropic fluids that possess only short-range orientational and positional order, in which the only macroscopically broken symmetry is chirality - even though the phases are formed from achiral molecules. Their conglomerate domains exhibit optical rotatory powers comparable to the highest ever found for isotropic fluids of chiral molecules.

  19. Synthesis of chiral dopants based on carbohydrates.

    PubMed

    Tsuruta, Toru; Koyama, Tetsuo; Yasutake, Mikio; Hatano, Ken; Matsuoka, Koji

    2014-07-01

    Chiral dopants based on carbohydrates for nematic liquid crystals were synthesized from D-glucose, and their helical twisting power (HTP) values were evaluated. The chiral dopants induced helices in the host nematic liquid crystals. An acetyl derivative having an ether-type glycosidic linkage between carbohydrate and a mesogenic moiety showed the highest HTP value of 10.4 μm(-1), while an acetyl derivative having an anomeric ester-type linkage did not show any HTP. It was surprising that this molecule had no HTP despite the presence of chirality in the molecule. A relationship between HTP and specific rotation was not observed in this study.

  20. A lattice chiral theory with multifermion couplings

    NASA Astrophysics Data System (ADS)

    Xue, She-Sheng

    1996-02-01

    Analyzing an SUL(2) ⊗ UR(1) chiral theory with multifermion couplings on a lattice, we find a possible region in the phase space of multifermion couplings, where no spontaneous symmetry breaking occurs, doublers are decoupled as massive Dirac fermions consistently with the SUL(2) ⊗ UR(1) chiral symmetry, the “spectator” fermion ψR( x) is free mode, whereas the normal mode of ψLi( x) is plausibly speculated to be chiral in the continuum limit. This is not in agreement with the general belief of the definite failure of theories so constructed.