WorldWideScience

Sample records for chiral molecular ferrimagnets

  1. Chiral forces and molecular dissymmetry

    International Nuclear Information System (INIS)

    Chiral molecules leading to helical macromolecules seem to preserve information and extend it better. In the biological world RNA is the very paradigm for self-replication, elongation and autocatalytic editing. The nucleic acid itself is not chiral. It acquires its chirality by association with D-sugars. Although the chiral information or selectivity put in by the unit monomer is no longer of much interest to the biologists - they tend to leave it to the Darwinian selection principle to take care of it as illustrated by Frank's model - it is vital to understand the origin of chirality. There are three different approaches for the chiral origin of life: (1) Phenomenological, (2) Electromagnetic molecular and Coriolis forces and (3) Atomic or nuclear force, the neutral weak current. The phenomenological approach involves spontaneous symmetry breaking fluctuations in far for equilibrium systems or nucleation and crystallization. Chance plays a major role in the chiral molecule selected

  2. A molecular propeller effect for chiral separation and analysis

    OpenAIRE

    Clemens, Jonathon B.; Kibar, Osman; Chachisvilis, Mirianas

    2015-01-01

    Enantiomers share nearly identical physical properties but have different chiral geometries, making their identification and separation difficult. Here we show that when exposed to a rotating electric field, the left- and right-handed chiral molecules rotate with the field and act as microscopic propellers; moreover, owing to their opposite handedness, they propel along the axis of field rotation in opposite directions. We introduce a new molecular parameter called hydrodynamic chirality to c...

  3. Molecular-Level Design of Heterogeneous Chiral Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Francisco Zaera

    2012-03-21

    , and the development of ways to imprint chiral centers on achiral solid surfaces. Chiral catalysis is not only a problem of great importance in its own right, but also the ultimate test of how to control selectivity in catalysis. The time is ripe for fundamental work in heterogeneous chiral catalysis to provide the U.S. with a leadership role in developing the next generation of catalytic processes for medicinal and agrochemical manufacturing. Our team provides the required expertise for a synergistic and comprehensive integration of physical and chemical experimentation with solid state and molecular reactivity theories to solve this problem.

  4. Molecular-level Design of Heterogeneous Chiral Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gellman, Andrew John [Carnegie Mellon University; Sholl, David S. [Georgia Institute of Technology; Tysoe, Wilfred T. [University of Wisconsin - Milwaukee; Zaera, Francisco [University of California at Riverside

    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

  5. Preparation of Chiral 1,4-Phenylene-silicas via Chiral Low-molecular-weight Amphiphiles

    Institute of Scientific and Technical Information of China (English)

    XIAO Min; LIU Xiao-juan; HU Kai; WU Li-min; LI Yi; LI Bao-zong; YANG Yong-gang

    2012-01-01

    Chiral organic-inorganic hybrid silicas can be prepared via the self-assemblies of chiral surfactants and gelators as templates.However,the relationship between the chirality of the hybrid silica and the structure of the surfactant/gelator has not been systemically studied.Herein,a series of chiral low-molecular-weight amphiphiles(LMWAs) derived from L-valine was synthesized.Their alkyl chains were n-butadecyl,n-hexadecyl and n-octadecyl,respectively.They can form viscous liquids in pure water,and physical gels in tetrahydrofuran,cyclohexanone,acetonitrile,acetone,chlorobenzene and nitrobenzenc.Chiral 1,4-phenylene-silicas were prepared via the self-assemblies of these LMWAs as templates.With increasing the alkyl chain length,the 1,4-phenylene-silicas changed from short mesoporous nanorods to long nanotubcs. The circular dichroism spectra of the 1,4-phenylene-silicas indicated that the long nanotubes exhibit the strongest chirality.

  6. Supramolecular Chirality: Solvent Chirality Transfer in Molecular Chemistry and Polymer Chemistry

    Directory of Open Access Journals (Sweden)

    Michiya Fujiki

    2014-08-01

    Full Text Available Controlled mirror symmetry breaking arising from chemical and physical origin is currently one of the hottest issues in the field of supramolecular chirality. The dynamic twisting abilities of solvent molecules are often ignored and unknown, although the targeted molecules and polymers in a fluid solution are surrounded by solvent molecules. We should pay more attention to the facts that mostly all of the chemical and physical properties of these molecules and polymers in the ground and photoexcited states are significantly influenced by the surrounding solvent molecules with much conformational freedom through non-covalent supramolecular interactions between these substances and solvent molecules. This review highlights a series of studies that include: (i historical background, covering chiral NaClO3 crystallization in the presence of d-sugars in the late 19th century; (ii early solvent chirality effects for optically inactive chromophores/fluorophores in the 1960s–1980s; and (iii the recent development of mirror symmetry breaking from the corresponding achiral or optically inactive molecules and polymers with the help of molecular chirality as the solvent use quantity.

  7. Design and synthesis of novel chiral molecular tweezers based on deoxycholic acid

    Institute of Scientific and Technical Information of China (English)

    Zhi Gang Zhao; Xing Li Liu; Yi Zhong

    2008-01-01

    A novel type of chiral molecular tweezers has been designed and synthesized by using deoxycholic acid as backbone and ethanoyl and the chiral unsymmetrical urea unit as arms. Their structures were characterized by 1H NMR, IR, MS spectra and elemental analysis. These molecular tweezers showed good binding ability for neutral molecules and chiral molecules.

  8. Molecular spinning by a chiral train of short laser pulses

    CERN Document Server

    Floß, Johannes

    2012-01-01

    We provide a detailed theoretical analysis of molecular rotational excitation by a chiral pulse train -- a sequence of linearly polarised pulses with the polarisation direction rotating from pulse to pulse by a controllable angle. Molecular rotation with a preferential rotational sense (clockwise or counter-clockwise) can be excited by this scheme. We show that the directionality of the rotation is caused by quantum interference of different excitation pathways. The chiral pulse train is capable of selective excitation of molecular isotopologues and nuclear spin isomers in a mixture. We demonstrate this using 14N2 and 15N2 as examples for isotopologues, and para- and ortho-nitrogen as examples for nuclear spin isomers.

  9. Louis Pasteur, language, and molecular chirality. I. Background and dissymmetry.

    Science.gov (United States)

    Gal, Joseph

    2011-01-01

    Louis Pasteur resolved sodium ammonium (±)-tartrate in 1848, thereby discovering molecular chirality. Although hindered by the primitive state of organic chemistry, he introduced new terminology and nomenclature for his new science of molecular and crystal chirality. He was well prepared for this task by his rigorous education and innate abilities, and his linguistic achievements eventually earned him membership in the supreme institution for the French language, the Académie française. Dissymmetry had been in use in French from the early 1820s for disruption or absence of symmetry or for dissimilarity or difference in appearance between two objects, and Pasteur initially used it in the latter connotation, without any reference to handedness or enantiomorphism. Soon, however, he adopted it in the meaning of chirality. Asymmetry had been in use in French since 1691 but Pasteur ignored it in favor of dissymmetry. The two terms are not synonymous but it is not clear whether Pasteur recognized this difference in choosing the former over the latter. However, much of the literature mistranslates his dissymmetry as asymmetry. Twenty years before Pasteur the British polymath John Herschel proposed that optical rotation in the noncrystalline state is due to the "unsymmetrical" [his term] nature of the molecules and later used dissymmetrical for handed. Chirality, coined by Lord Kelvin in 1894 and introduced into chemistry by Mislow in 1962, has nearly completely replaced dissymmetry in the meaning of handedness, but the use of dissymmetry continues today in other contexts for lack of symmetry, reduction of symmetry, or dissimilarity.

  10. Design and Synthesis of Chiral Molecular Tweezers Based on Deoxycholic Acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A series of new chiral molecular tweezers have been designed and synthesized by using deoxycholic acid as spacer and aromatic amines as arms.Instead of using toxic phosgene,the triphosgene was employed in synthesis of the molecular tweezers receptors.These chiral molecular tweezers showed good enantioselectivity for D-amino acid methyl esters.

  11. Chiral Analysis of Isopulegol by Fourier Transform Molecular Rotational Spectroscopy

    Science.gov (United States)

    Evangelisti, Luca; Seifert, Nathan A.; Spada, Lorenzo; Pate, Brooks

    2016-06-01

    Chiral analysis on molecules with multiple chiral centers can be performed using pulsed-jet Fourier transform rotational spectroscopy. This analysis includes quantitative measurement of diastereomer products and, with the three wave mixing methods developed by Patterson, Schnell, and Doyle (Nature 497, 475-477 (2013)), quantitative determination of the enantiomeric excess of each diastereomer. The high resolution features enable to perform the analysis directly on complex samples without the need for chromatographic separation. Isopulegol has been chosen to show the capabilities of Fourier transform rotational spectroscopy for chiral analysis. Broadband rotational spectroscopy produces spectra with signal-to-noise ratio exceeding 1000:1. The ability to identify low-abundance (0.1-1%) diastereomers in the sample will be described. Methods to rapidly identify rotational spectra from isotopologues at natural abundance will be shown and the molecular structures obtained from this analysis will be compared to theory. The role that quantum chemistry calculations play in identifying structural minima and estimating their spectroscopic properties to aid spectral analysis will be described. Finally, the implementation of three wave mixing techniques to measure the enantiomeric excess of each diastereomer and determine the absolute configuration of the enantiomer in excess will be described.

  12. Performance of chiral zeolites for enantiomeric separation revealed by molecular simulation

    NARCIS (Netherlands)

    J.M. Castillo; T.J.H. Vlugt; D. Dubbeldam; S. Hamad; S. Calero

    2010-01-01

    We used molecular simulations to test the adsorption selectivity for enantiomers in the chiral zeolites SOF, STW, and ITQ-37. This work is the first simulation study which demonstrates the chirality of SOF, STW, and ITQ-37. We obtain information at the molecular level that explains the nature of the

  13. Breathers in ferrimagnetic systems

    Indian Academy of Sciences (India)

    Tarashankar Nag; Swapan Kumar Das; Ajoy Chowdhury

    2006-09-01

    Breathers in discrete nonlinear ferrimagnetic spin lattices are investigated for both easy-axis and easy-plane configurations. The region in frequency space of the formation of breathers is determined and the anticontinuum limit discussed. The mono-chromatic and the coloured breathers are found out numerically for different parameters and different conditions of excitations.

  14. Chiral separation of racemic drugs using molecular imprinting

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Molecularly imprinted polymers (MIPs) of (S)-ketoprofen and (S)-naproxen are prepared using non-covalent imprinting in the presence of template molecules. The prepared MIPs are used as the chiral stationary phase to separate ramemic naproxen and ketoprofen. The results show that racemic naproxen and ketoprofen are efficiently resolved on MIPs. The effect of concentration of acetic acid in the mobile phase is studied, and the data are analyzed using the affinity chromatography model, and the close agreement is achieved between the simulated and experimental curves. The results suggest that the affinity chromatography mechanism controls the retention in this system. Moreover, the affinity chromatography equilibrium constants on (S)-naproxen and (S)-ketoprofen are estimated.

  15. Volume anomaly in ferrimagnetism

    OpenAIRE

    Pascard, H.; Globus, A.

    1981-01-01

    The volume anomaly ΔV/V due to the magnetic energy corresponding to the exchange interactions is experimentally determined for YIG. The experimental values (from 77 K to Tc) agree with the values deduced from the theoretical expression based on the Néel's theories of volume anomaly and of ferrimagnetism. These results are compared with those obtained by other authors on ferromagnetic and antiferromagnetic materials with localized magnetic moments : a reduced curve is obtained.

  16. Measuring the optical chirality of molecular aggregates at liquid-liquid interfaces.

    Science.gov (United States)

    Watarai, Hitoshi; Adachi, Kenta

    2009-10-01

    Some new experimental methods for measuring the optical chirality of molecular aggregates formed at liquid-liquid interfaces have been reviewed. Chirality measurements of interfacial aggregates are highly important not only in analytical spectroscopy but also in biochemistry and surface nanochemistry. Among these methods, a centrifugal liquid membrane method was shown to be a highly versatile method for measuring the optical chirality of the liquid-liquid interface when used in combination with a commercially available circular dichroism (CD) spectropolarimeter, provided that the interfacial aggregate exhibited a large molar absorptivity. Therefore, porphyrin and phthalocyanine were used as chromophoric probes of the chirality of itself or guest molecules at the interface. A microscopic CD method was also demonstrated for the measurement of a small region of a film or a sheet sample. In addition, second-harmonic generation and Raman scattering methods were reviewed as promising methods for detecting interfacial optical molecules and measuring bond distortions of chiral molecules, respectively.

  17. Chiral Nanoscience and Nanotechnology

    OpenAIRE

    Dibyendu S. Bag; T.C. Shami; K.U. Bhasker Rao

    2008-01-01

    The paper reviews nanoscale science and technology of chiral molecules/macromolecules-under twosubtopics-chiral nanotechnology and nano-chiral technology. Chiral nanotechnology discusses thenanotechnology, where molecular chirality plays a role in the properties of materials, including molecularswitches, molecular motors, and other molecular devices; chiral supramolecules and self-assembled nanotubesand their functions are also highlighted. Nano-chiral technology  describes the nanoscale appr...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. Resonant second-harmonic-generation circular-dichroism microscopy reveals molecular chirality in native biological tissues

    CERN Document Server

    Chen, Mei-Yu; Kan, Che-Wei; Lin, Yen-Yin; Ye, Cin-Wei; Wu, Meng-Jer; Liu, Hsiang-Lin; Chu, Shi-Wei

    2016-01-01

    Conventional linear optical activity effects are widely used for studying chiral materials. However, poor contrast and artifacts due to sample anisotropy limit the applicability of these methods. Here we demonstrate that nonlinear second-harmonic-generation circular dichroism spectral microscopy can overcome these limits. In intact collagenous tissues, clear spectral resonance is observed with sub-micrometer spatial resolution. By performing gradual protein denaturation studies, we show that the resonant responses are dominantly due to the molecular chirality.

  1. Enantiopure Functional Molecular Motors Obtained by a Switchable Chiral-Resolution Process.

    Science.gov (United States)

    van Leeuwen, Thomas; Gan, Jefri; Kistemaker, Jos C M; Pizzolato, Stefano F; Chang, Mu-Chieh; Feringa, Ben L

    2016-05-17

    Molecular switches, rotors, and motors play an important role in the development of nano-machines and devices, as well as responsive and adaptive functional materials. For unidirectional rotors based on chiral overcrowded alkenes, their stereochemical homogeneity is of crucial importance. Herein, a method to obtain new and functionalizable overcrowded alkenes in enantiopure form is presented. The procedure involves a short synthesis of three steps and a solvent-switchable chiral resolution by using a readily available resolving agent. X-ray crystallography revealed the mode of binding of the motor with the resolving agent, as well as the absolute configuration of the motor. (1) H NMR and UV/Vis spectroscopy techniques were used to determine the dynamic behavior of this molecular motor. This method provides rapid access to ample amounts of enantiopure molecular motors, which will greatly facilitate the further development of responsive molecular systems based on chiral overcrowded alkenes. PMID:27072290

  2. Liquid Crystal Phases of Molecular Bananas: Polarity and Chirality as Broken Symmetries

    Science.gov (United States)

    Clark, Noel

    2006-03-01

    The study of the interplay of chirality and polarity has been a particularly rich theme of soft matter science since Meyer's seminal discovery that tilted smectics of chiral molecules are macroscopically polar. This event, and the subsequent realization of polar domains and high-speed electro-optic switching in chiral smectics, engaged the liquid crystal community in a worldwide pursuit of novel smectics for applications, featured by the synthesis of more than 50,000 new liquid crystal compounds, and by a consequent broad diversification of the palette of liquid crystal phases and possibilities for supermolecular ordering. A current important activity in this scenario is the study of polar order in synthetically achiral molecules, for example, in molecular bananas, which, as their shape suggests, might be expected to organize in a polar way. Indeed they do, but beyond this, almost everything learned about them has been surprising, including their persistent tendency to exhibit chirality as a spontaneously broken symmetry. I will discuss some of these new phases and phenomena, including the discovery of fluid conglomerates (Pasteur's experiment in a fluid), triclinic fluid order, chiral twist grain boundary phases of achiral molecules, chirality flipping and field-induced deracemization, ferroelectric and antiferroelectric phases with supermolecular- scale polarization modulation, and chiral thermotropic sponge phases.

  3. Dynamic phase diagrams and compensation behaviors in molecular-based ferrimagnet A F eΙΙ F eΙΙΙ(C2O4)3 under an oscillating magnetic field

    Science.gov (United States)

    Shi, Xiaoling; Wang, Li; Zhao, Jie; Xu, Xingguang

    2016-07-01

    Within the effective-field theory (EFT), the compensation behaviors in molecular-based ferrimagnet A F eΙΙ F e Ι Ι Ι(C2O4)3 which is described by a mixed spin-2 (FeΙΙ) and spin-5/2 (FeΙΙΙ) ferrimagnetic Ising model on a honeycomb lattice are studied. The Glauber-type stochastic dynamic is used to describe the time evolution of the system under an oscillating magnetic field. A magnetic field dependence of the compensation temperature and a temperature dependence of compensating magnetic field are calculated and both curves agree qualitatively with experimental data. In particular, a two-compensation-points phenomenon which has been reported in the experimental work is also observed in this compound. Dynamic phase boundaries containing the compensation points are calculated. The dynamic tricritical point and critical end point exist on the phase transition lines. Comparing with previous theoretical results obtained by the mean-field theory (MFT), the effective-field theory results show a reasonable improvement over the MFT results.

  4. Molecular Dynamic Study for Chiral Discrimination of a -Phenylethylamine by Modified Cyclodextrin in Gas Chromatography

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A molecular dynamic method in conjunction with a statistic test has been utilized to model chiral recognition of a -phenylethylamine on heptakis (2,6-di-O-butyl-3-O-butyryl)-b -cyclodextrin in gas chromatography. The modelling data correlated with the chromatographic elution order, and indicated that the preferred site of a -phenylethylamine is the interior of cavity.

  5. Molecular chirality and the orbital angular momentum of light

    CERN Document Server

    Andrews, D L; Babiker, M; Andrews, David L.; Romero, Luciana C. Davila; Babiker, Mohamed

    2003-01-01

    Optical beams with a new and distinctive type of helicity have become the subject of much recent interest. While circularly polarised light comprises photons with spin angular momentum, these optically engineered 'twisted beams' (optical vortices) are endowed with orbital angular momentum. Here, the wave- front surface of the electromagnetic fields assumes helical form. To date, optical vortices have generally been studied only in their interactions with achiral matter. This study assesses what new features, if any, can be expected when such beams are used to interrogate a chiral system.

  6. Molecular Recognition of Biomolecules by Chiral CdSe Quantum Dots

    Science.gov (United States)

    Mukhina, Maria V.; Korsakov, Ivan V.; Maslov, Vladimir G.; Purcell-Milton, Finn; Govan, Joseph; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun’Ko, Yurii K.

    2016-04-01

    Molecular recognition is one of the most important phenomena in Chemistry and Biology. Here we present a new way of enantiomeric molecular recognition using intrinsically chiral semiconductor nanocrystals as assays. Real-time confocal microscopy studies supported by circular dichroism spectroscopy data and theoretical modelling indicate an ability of left-handed molecules of cysteine and, to a smaller extent, histidine and arginine to discriminate between surfaces of left- and right-handed nanocrystals.

  7. Molecular chirality in meteorites and interstellar ices, and the chirality experiment on board the ESA cometary Rosetta mission.

    Science.gov (United States)

    Myrgorodska, Iuliia; Meinert, Cornelia; Martins, Zita; Le Sergeant d'Hendecourt, Louis; Meierhenrich, Uwe J

    2015-01-26

    Life, as it is known to us, uses exclusively L-amino acid and D-sugar enantiomers for the molecular architecture of proteins and nucleic acids. This Minireview explores current models of the original symmetry-breaking influence that led to the exogenic delivery to Earth of prebiotic molecules with a slight enantiomeric excess. We provide a short overview of enantiomeric enhancements detected in bodies of extraterrestrial origin, such as meteorites, and interstellar ices simulated in the laboratory. Data are interpreted from different points of view, namely, photochirogenesis, parity violation in the weak nuclear interaction, and enantioenrichment through phase transitions. Photochemically induced enantiomeric imbalances are discussed more specifically in the topical context of the "chirality module" on board the cometary Rosetta spacecraft of the ESA. This device will perform the first enantioselective in situ analyses of samples taken from a cometary nucleus. PMID:25431250

  8. Magnetic Properties of Quantum Ferrimagnetic Spin Chains

    OpenAIRE

    Yamamoto, Shoji

    1998-01-01

    Magnetic susceptibilities of spin-$(S,s)$ ferrimagnetic Heisenberg chains are numerically investigated. It is argued how the ferromagnetic and antiferromagnetic features of quantum ferrimagnets are exhibited as functions of $(S,s)$. Spin-$(S,s)$ ferrimagnetic chains behave like combinations of spin-$(S-s)$ ferromagnetic and spin-$(2s)$ antiferromagnetic chains provided $S=2s$.

  9. True and false chirality, CP violation, and the breakdown of microscopic reversibility in chiral molecular and elementary particle processes

    International Nuclear Information System (INIS)

    The concept of chirality is extended to cover systems that exhibit enantiomorphism on account of motion. This is achieved by applying time reversal in addition to space inversion and leads to a more precise definition of a chiral system. Although spatial enantiomorphism is sufficient to guarantee chirality in a stationary system such as a finite helix, enantiomorphous systems are not necessarily chiral when motion is involved, which leads to the concept of true and false chirality associated with time-invariant and time-noninvariant enantiomorphism, respectively. Only a truly chiral influence can induce an enantiomeric excess in a reaction that has reached true thermodynamic equilibrium (i.e., when all possible interconversion pathways have equilibrated); however, false chirality can suffice in a reaction under kinetic control due to a breakdown of microscopic reversibility analogous to that observed in particle-antiparticle processes involving the neutral K-meason as a result of CP violation, with the apparently contradictory kinetic and thermodynamic aspects being reconciled by an appeal to unitarity. This reveals that CP violation is analogous to chemical catalysis since it affects the rates of certain particle-antiparticle interconversion pathways without affecting the initial and final particle energies and hence the equilibrium thermodynamics. Consideration of falsely chiral influences, including the open-quote ratchet effect close-quote arising from the associated breakdown in microscopic reversibility, greatly enlarges the range of possible chiral advantage factors in prebiotic chemical processes if far from equilibrium. copyright 1996 American Institute of Physics

  10. CD Spectroscopic Study on the Molecular Recognition of Chiral Salen-Metal Complexes

    Institute of Scientific and Technical Information of China (English)

    刘涛; 阮文娟; 南晶; 朱志昂

    2003-01-01

    The molecular recognition behavior of the chiral salen-metal complexes towards guest molecules, such as imidazole derivatives and amino-acid ester, was systematically investigated by means of circular dichroism (CD) spectra. The coordination numbers of the host-guest complexes as well as the recognition capability of the salen-metal complexes were explained by character and intensity analyses of the CD spectra.

  11. Induction of molecular chirality by circularly polarized light in cyclic azobenzene with a photoswitchable benzene rotor.

    Science.gov (United States)

    Hashim, P K; Thomas, Reji; Tamaoki, Nobuyuki

    2011-06-20

    New phototriggered molecular machines based on cyclic azobenzene were synthesized in which a 2,5-dimethoxy, 2,5-dimethyl, 2,5-difluorine or unsubstituted-1,4-dioxybenzene rotating unit and a photoisomerizable 3,3'-dioxyazobenzene moiety are bridged together by fixed bismethylene spacers. Depending upon substitution on the benzene moiety and on the E/Z conformation of the azobenzene unit, these molecules suffer various degrees of restriction on the free rotation of the benzene rotor. The rotation of the substituted benzene rotor within the cyclic azobenzene cavity imparts planar chirality to the molecules. Cyclic azobenzene 1, with methoxy groups at both the 2- and 5-positions of the benzene rotor, was so conformationally restricted that free rotation of the rotor was prevented in both the E and Z isomers and the respective planar chiral enantiomers were resolved. In contrast, compound 2, with 2,5-dimethylbenzene as the rotor, demonstrated the property of a light-controlled molecular brake, whereby rotation of the 2,5-dimethylbenzene moiety is completely stopped in the E isomer (brake ON, rotation OFF), while the rotation is allowed in the Z isomer (brake OFF, rotation ON). The cyclic azobenzene 3, with fluorine substitution on the benzene rotor, was in the brake OFF state regardless of E/Z photoisomerization of the azobenzene moiety. More interestingly, for the first time, we demonstrated the induction of molecular chirality in a simple monocyclic azobenzene by circular-polarized light. The key characteristics of cyclic azobenzene 2, that is, stability of the chiral structure in the E isomer, fast racemization in the Z isomer, and the circular dichroism of enantiomers of both E and Z isomers, resulted in a simple reversible enantio-differentiating photoisomerization directly between the E enantiomers. Upon exposure to r- or l-circularly polarized light at 488 nm, partial enrichment of the (S)- or (R)-enantiomers of 2 was observed. PMID:21567494

  12. Design Molecular Recognition Materials for Chiral Sensors, Separtations and Catalytic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jia, S.; Nenoff, T.M.; Provencio, P.; Qiu, Y.; Shelnutt, J.A.; Thoma, S.G.; Zhang, J.

    1998-11-01

    The goal is the development of materials that are highly sensitive and selective for chid chemicals and biochemical (such as insecticides, herbicides, proteins, and nerve agents) to be used as sensors, catalysts and separations membranes. Molecular modeling methods are being used to tailor chiral molecular recognition sites with high affinity and selectivity for specified agents. The work focuses on both silicate and non-silicate materials modified with chirally-pure fictional groups for the catalysis or separations of enantiomerically-pure molecules. Surfactant and quaternary amine templating is being used to synthesize porous frameworks, containing mesopores of 30 to 100 angstroms. Computer molecukw modeling methods are being used in the design of these materials, especially in the chid surface- modi~ing agents. Molecular modeling is also being used to predict the catalytic and separations selectivities of the modified mesoporous materials. The ability to design and synthesize tailored asymmetric molecular recognition sites for sensor coatings allows a broader range of chemicals to be sensed with the desired high sensitivity and selectivity. Initial experiments target the selective sensing of small molecule gases and non-toxic model neural compounds. Further efforts will address designing sensors that greatly extend the variety of resolvable chemical species and forming a predictive, model-based method for developing advanced sensors.

  13. From the double-stranded helix to the chiral nematic phase of B-DNA: a molecular model

    CERN Document Server

    Tombolato, F

    2004-01-01

    B-DNA solutions of suitable concentration form left-handed chiral nematic phases (cholesterics). Such phases have also been observed in solutions of other stiff or semiflexible chiral polymers; magnitude and handedness of the cholesteric pitch are uniquely related to the molecular features. In this work we present a theoretical method and a numerical procedure which, starting from the structure of polyelectrolytes, lead to the prediction of the cholesteric pitch. Molecular expressions for the free energy of the system are obtained on the basis of steric and electrostatic interactions between polymers; the former are described in terms of excluded volume, while a mean field approximation is used for the latter. Calculations have been performed for 130 bp fragments of B-DNA. The theoretical predictions provide an explanation for the experimental behavior, by showing the counteracting role played by shape and charge chirality of the molecule.

  14. Molecularly Imprinted Polymers for the Identification and Separation of Chiral Drugs and Biomolecules

    Directory of Open Access Journals (Sweden)

    Sha Yang

    2016-06-01

    Full Text Available Molecularly imprinting polymers (MIPs have been extensively applied in chromatography for the separation of chiral drugs. In this review, we mainly summarize recent developments of various MIPs used as chiral stationary phases (CSPs in high performance liquid chromatography (HPLC, capillary electrochromatography (CEC, and supercritical fluid chromatography (SFC. Among them, HPLC has the advantages of straightforward operation and high selectivity. However, the low separation efficiency, due to slow interaction kinetics and heavy peak broadening, is the main challenge for the application of MIPs in HPLC. On the other hand, CEC possesses both the high selectivity of HPLC and the high efficiency of capillary electrophoresis. In CEC, electroosmotic flow is formed across the entire column and reduces the heavy peak broadening observed in HPLC mode. SFC can modify the low interaction kinetics in HPLC when supercritical fluids are utilized as mobile phases. If SFC and MIP-based CSPs can be well combined, better separation performance can be achieved. Particles, monoliths and membrane are typical formats of MIPs. Traditional MIP particles produced by bulk polymerization have been replaced by MIP particles by surface imprinting technology, which are highly consistent in size and shape. Monolithic MIPs are prepared by in situ method in a column, greatly shortening the pre-preparation time. Some novel materials, such as magnetic nanoparticles, are integrated into the MIPs to enhance the controllability and efficiency of the polymerization. This review will be helpful to guide the preparation, development, and application of MIPs in chromatographic and electrophoretic enantioseparation.

  15. Molecular Modeling Study of Chiral Separation and Recognition Mechanism of β-Adrenergic Antagonists by Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Yifeng Chai

    2012-01-01

    Full Text Available Chiral separations of five β-adrenergic antagonists (propranolol, esmolol, atenolol, metoprolol, and bisoprolol were studied by capillary electrophoresis using six cyclodextrins (CDs as the chiral selectors. Carboxymethylated-β-cyclodextrin (CM-β-CD exhibited a higher enantioselectivity power compared to the other tested CDs. The influences of the concentration of CM-β-CD, buffer pH, buffer concentration, temperature, and applied voltage were investigated. The good chiral separation of five β-adrenergic antagonists was achieved using 50 mM Tris buffer at pH 4.0 containing 8 mM CM-β-CD with an applied voltage of 24 kV at 20 °C. In order to understand possible chiral recognition mechanisms of these racemates with CM-β-CD, host-guest binding procedures of CM-β-CD and these racemates were studied using the molecular docking software Autodock. The binding free energy was calculated using the Autodock semi-empirical binding free energy function. The results showed that the phenyl or naphthyl ring inserted in the hydrophobic cavity of CM-β-CD and the side chain was found to point out of the cyclodextrin rim. Hydrogen bonding between CM-β-CD and these racemates played an important role in the process of enantionseparation and a model of the hydrogen bonding interaction positions was constructed. The difference in hydrogen bonding formed with the –OH next to the chiral center of the analytes may help to increase chiral discrimination and gave rise to a bigger separation factor. In addition, the longer side chain in the hydrophobic phenyl ring of the enantiomer was not beneficial for enantioseparation and the chiral selectivity factor was found to correspond to the difference in binding free energy.

  16. Enantiodifferentiation of chiral baclofen by β-cyclodextrin using capillary electrophoresis: A molecular modeling approach

    Science.gov (United States)

    Suliman, FakhrEldin O.; Elbashir, Abdalla A.

    2012-07-01

    Using capillary electrophoresis baclofen (BF) enantiomers were separated only in the presence of β-cyclodextrin (βCD) as a chiral selector when added to the background electrolyte. Proton nuclear magnetic resonance and electrospray ionization mass spectrometry (ESI-MS) techniques were used to determine the structure of the BF-βCD inclusion complexes. From the MS data BF was found to form a 1:1 complex with α- and βCD, while the NMR data suggest location of the aromatic ring of BF into the cyclodextrin cavity. A molecular modeling study, using the semiempirical PM6 calculations was used to investigate the mechanism of enantiodifferentiation of BF with cyclodextrins. Optimization of the structures of the complexes by PM6 method indicated that separation is obtained in the presence of β-CD due to a large binding energy difference (ΔΔE) of 46.8 kJ mol-1 between S-BF-βCD and R-BF-βCD complexes. In the case of αCD complexes ΔΔE was 1.3 kJ mol-1 indicating poor resolution between the two enantiomers. Furthermore, molecular dynamic simulations show that the formation of more stable S-BF-βCD complex compared to R-BF-β-CD complex is primarily due to differences in intermolecular hydrogen bonding.

  17. The Question of Absolute Space and Time Directions in Relation to Molecular Chirality, Parity Violation, and Biomolecular Homochirality

    Energy Technology Data Exchange (ETDEWEB)

    Quack, Martin (ETH - Zurich)

    2001-03-21

    The questions of the absolute directions of space and time or the “observability” of absolute time direction as well as absolute handedness-left or right- are related to the fundamental symmetries of physics C, P, T as well as their combinations, in particular CPT, and their violations, such as parity violation. At the same time there is a relation to certain still open questions in chemistry concerning the fundamental physical- chemical principles of molecular chirality and in biochemistry concerning the selection of homochirality in evolution. In the lecture we shall introduce the concepts and then report new theoretical results from our work on parity violation in chiral molecules, showing order of magnitude increases with respect to previously accepted values. We discus as well our current experimental efforts. We shall briefly mention the construction of an absolute molecular clock.

  18. The Question of Absolute Space and Time Directions in Relation to Molecular Chirality, Parity Violation, and Biomolecular Homochirality

    Energy Technology Data Exchange (ETDEWEB)

    Quack, Martin (ETH - Zurich)

    2001-03-21

    The questions of the absolute directions of space and time or the 'observability' of absolute time direction as well as absolute handedness - left or right - are related to the fundamental symmetries of physics C, P, T as well as their combinations, in particular CPT, and their violations, such as parity violation. At the same time there is a relation to certain still open questions in chemistry concerning the fundamental physical-chemical principles of molecular chirality and in biochemistry concerning the selection of homochirality in evolution. In the lecture we shall introduce the concepts and then report new theoretical results from our work on parity violation in chiral molecules, showing order of magnitude increases with respect to previously accepted values. We discuss as well our current experimental efforts. We shall briefly mention the construction of an absolute molecular clock.

  19. Molecular and Merrifield supported chiral diamines for enantioselective addition of ZnR2 (R = Me, Et) to ketones.

    Science.gov (United States)

    Calvillo-Barahona, Mercedes; Cordovilla, Carlos; Genov, Miroslav N; Martínez-Ilarduya, Jesús M; Espinet, Pablo

    2013-10-28

    Chiral 1,2-ethylenediamines have been previously reported as active catalysts in the enantioselective addition reactions of ZnR2 to either methyl- or trifluoromethyl-ketones. Subtle changes in the molecular structure of different catalysts are described herein and lead to a dramatic effect in their catalytic activity. From these findings, we demonstrate the selective reactivity of the ligands used in the addition of ZnR2 (R = Me, Et) to methyl- and trifluoromethyl-ketones offering an enantioselective access either to chiral non-fluorinated alcohols or to chiral fluorinated tertiary alcohols. Considering the importance of the chiral trifluoromethyl carbinol fragment in several biologically active compounds, we have extended the scope of the addition reaction of ZnEt2 to several trifluoromethylketones catalyzed by (R,R)-1,2-diphenylethylenediamine derivatives. This work explores a homogeneous approach that provides excellent yields and very high ee and the use of a heterogenized tail-tied ligand affording moderate ee, high yields and allowing an easier handling and recycling.

  20. Chirality in Nonlinear Optics

    Science.gov (United States)

    Haupert, Levi M.; Simpson, Garth J.

    2009-05-01

    The past decade has witnessed the emergence of new measurement approaches and applications for chiral thin films and materials enabled by the observations of the high sensitivity of second-order nonlinear optical measurements to chirality. In thin films, the chiral response to second harmonic generation and sum frequency generation (SFG) from a single molecular monolayer is often comparable with the achiral response. The chiral specificity also allows for symmetry-allowed SFG in isotropic chiral media, confirming predictions made ˜50 years ago. With these experimental demonstrations in hand, an important challenge is the construction of intuitive predictive models that allow the measured chiral response to be meaningfully related back to molecular and macromolecular structure. This review defines and considers three distinct mechanisms for chiral effects in uniaxially oriented assemblies: orientational chirality, intrinsic chirality, and isotropic chirality. The role of each is discussed in experimental and computational studies of bacteriorhodopsin films, binaphthol, and collagen. Collectively, these three model systems support a remarkably simple framework for quantitatively recovering the measured chiral-specific activity.

  1. Chiral Rotational Spectroscopy

    CERN Document Server

    Cameron, Robert P; Barnett, Stephen M

    2015-01-01

    We introduce chiral rotational spectroscopy: a new technique that enables the determination of the individual optical activity polarisability components $G_{XX}'$, $G_{YY}'$, $G_{ZZ}'$, $A_{X,YZ}$, $A_{Y,ZX}$ and $A_{Z,XY}$ of chiral molecules, in a manner that reveals the enantiomeric constitution of a sample whilst yielding an incisive signal even for a racemate. Chiral rotational spectroscopy could find particular use in the analysis of molecules that are chiral by virtue of their isotopic constitution and molecules with multiple chiral centres. The principles that underpin chiral rotational spectroscopy can also be exploited in the search for molecular chirality in space, which, if found, may add weight to hypotheses that biological homochirality and indeed life itself are of cosmic origin.

  2. Control of molecular rotation with a chiral train of ultrashort pulses

    CERN Document Server

    Zhdanovich, S; Bloomquist, C; Floß, J; Averbukh, I Sh; Hepburn, J W; Milner, V

    2011-01-01

    Trains of ultrashort laser pulses separated by the time of rotational revival (typically, tens of picoseconds) have been exploited for creating ensembles of aligned molecules. In this work we introduce a chiral pulse train - a sequence of linearly polarized pulses with the polarization direction rotating from pulse to pulse by a controllable angle. The chirality of such a train, expressed through the period and direction of its polarization rotation, is used as a new control parameter for achieving selectivity and directionality of laser-induced rotational excitation. The method employs chiral trains with a large number of pulses separated on the time scale much shorter than the rotational revival (a few hundred femtosecond), enabling the use of conventional pulse shapers.

  3. Ferrimagnetic behaviors in a transverse Ising nanoisland

    Science.gov (United States)

    Kaneyoshi, T.

    2016-05-01

    In this paper, the phase diagrams and magnetizations of a magnetic nanoisland described by the transverse Ising model (TIM) are investigated by the use of the effective-field theory (EFT) with correlations. A lot of characteristic behaviors observed in standard ferrimagnetic materials as well as novel phenomena have been obtained, although the system consists of two finite spin-1/2 layers coupled antiferromagnetically with a negative interlayer coupling.

  4. Synthesis, molecular modeling, and biological evaluation of novel chiral thiosemicarbazone derivatives as potent anticancer agents.

    Science.gov (United States)

    Taşdemir, Demet; Karaküçük-İyidoğan, Ayşegül; Ulaşli, Mustafa; Taşkin-Tok, Tuğba; Oruç-Emre, Emİne Elçİn; Bayram, Hasan

    2015-02-01

    A series of new chiral thiosemicarbazones derived from homochiral amines in both enantiomeric forms were synthesized and evaluated for their in vitro antiproliferative activity against A549 (human alveolar adenocarcinoma), MCF-7 (human breast adenocarcinoma), HeLa (human cervical adenocarcinoma), and HGC-27 (human stomach carcinoma) cell lines. Some of compounds showed inhibitory activities on the growth of cancer cell lines. Especially, compound exhibited the most potent activity (IC50 4.6 μM) against HGC-27 as compared with the reference compound, sindaxel (IC50 10.3 μM), and could be used as a lead compound to search new chiral thiosemicarbazone derivatives as antiproliferative agents. PMID:25399965

  5. Effect of template on chiral separation of phenylalanine using molecularly imprinted membrane in aqueous medium

    International Nuclear Information System (INIS)

    Wet phase inversion method was used to prepare L-Phenylalanine (L-Phe) and D-Phenylalanine (D-Phe) imprinted poly ((acrylonitrile)-co-(acrylic acid)) membranes for chiral separation. Ultrafiltration experiments were conducted to evaluate the chiral separation ability of the prepared membrane towards racemate aqueous solution of Phenylalanine. The continuous permselectivity was observed by novel membrane. The chiral resolution ability of L-Phe imprinted membrane was much better than that of D-Phe. It was observed that both membranes simultaneously, selectively reject, selectively adsorbed and selectively permeate solute. The achieved adsorption selectivities of L-Phe imprinted membrane (AlphaAds)L and D-Phe imprinted membrane (AlphaAds)D were 2.6 and 2.40 respectively. Permselectivity of L-Phe imprinted membrane (AlphaPerm)L was 2.56 while D-Phe imprinted membrane permselectivity (AlphaPerm)D was 2.03. The rejection selectivities of L-Phe and D-Phe imprinted membranes were (AlphaRej)L=0.32 and (AlphaRej)D =0.28 respectively. (author)

  6. Ultrafast angular momentum transfer in multisublattice ferrimagnets.

    Science.gov (United States)

    Bergeard, N; López-Flores, V; Halté, V; Hehn, M; Stamm, C; Pontius, N; Beaurepaire, E; Boeglin, C

    2014-03-11

    Femtosecond laser pulses can be used to induce ultrafast changes of the magnetization in magnetic materials. However, one of the unsolved questions is that of conservation of the total angular momentum during the ultrafast demagnetization. Here we report the ultrafast transfer of angular momentum during the first hundred femtoseconds in ferrimagnetic Co0.8Gd0.2 and Co0.74Tb0.26 films. Using time-resolved X-ray magnetic circular dichroism allowed for time-resolved determination of spin and orbital momenta for each element. We report an ultrafast quenching of the magnetocrystalline anisotropy and show that at early times the demagnetization in ferrimagnetic alloys is driven by the local transfer of angular momenta between the two exchange-coupled sublattices while the total angular momentum stays constant. In Co0.74Tb0.26 we have observed a transfer of the total angular momentum to an external bath, which is delayed by ~150 fs.

  7. Molecular dynamics simulation of the effect of carbon nanotube chirality on nano-joining with gold particle

    International Nuclear Information System (INIS)

    The behavior of gold atoms depending on the CNT chirality in a nanojoining process is studied by molecular dynamics simulation. The deformation regularity and the diffusing characteristic of the gold particle during the joining process, as well as the C-Au bonds distribution in the final joint are studied. Our results show that when joining with higher spirality CNT, gold particle tends to deform more. With the CNT more similar to armchair type, the gold particle as a whole displaces more. In the final joint, the total bonds number decreases from typical armchair CNT to typical zig-zag CNT. However, the bonds distribution in detail is irregular from joint to joint, which is the consequence of lattice structure of both materials. (author)

  8. Magnetodielectric effect in relaxor/ferrimagnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Naveed Ul-Haq, M., E-mail: naveedulhaq07@gmail.com [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Institute for Materials Sciences and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Essen 45141 (Germany); Yunus, Tayyaba; Mumtaz, Arif [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Shvartsman, V.V.; Lupascu, Doru C. [Institute for Materials Sciences and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Essen 45141 (Germany)

    2015-08-15

    Highlights: • Single phase ferroelectric (relaxor)/ferrimagnetic composites are synthesized. • The composite shows magnetodielectric effect. • Effect of interface strain is discussed. • MD is explained via defining a local order parameter q(T). - Abstract: We report on the effect of an applied static magnetic field on the dielectric properties of ferroelectric relaxor/ferrimagnetic composites consisting of [Ba(Sn{sub 0.3}Ti{sub 0.7})O{sub 3}]{sub 0.8}–[CoFe{sub 2}O{sub 4}]{sub 0.2} (BST{sub 0.8}–CFO{sub 0.2}). The pure Ba(Sn{sub 0.3}Ti{sub 0.7})O{sub 3} (BST30) as well as the composites, were synthesized by solid state reaction method. The X-ray diffraction analysis confirmed that BST30 and CFO coexist in the composite without any secondary phase. The real and the imaginary part of the dielectric permittivity were studied as a function of temperature, with and without static magnetic field, respectively. Relaxor characteristics such as dielectric permittivity and its peak temperature are observed to vary with the magnetic field. This is explained in the context that the applied magnetic field creates magnetostriction in the ferrite phase which is transferred to the relaxor phase via the interface coupling. The strain in the relaxor phase results in the reorientation of local polarization entities, polar nano regions (PNRs), which alters the dielectric characteristics of the sample. This effect is explained in relation to local order parameter q(T) which is found to increase in a certain temperature range above the typical ferroelectric temperature regime with the application of magnetic field.

  9. On the Biological Advantage of Chirality

    CERN Document Server

    Gilat, G

    1999-01-01

    The presence of chirality in the main molecules of life may well be not just a structural artifact, but of pure biological advantage. The possibility of the existence of a phenomenon of a special mode of interaction, labeled as "chiral interaction" (CI), for which structural chirality is a necessary condition, is the main reason for such an advantage. In order to demonstrate such a possibility, macroscopic chiral devices are introduced and presented as analogies for such an interaction. For this purpose it is important to make a clear distinction between geometric and physical chiralities, where the latter are capable to perform chiral interactions with various media. Apart from chirality, a few other structural elements are required. In particular, the presence of an interface that separates between the chiral device and the medium with which it is interacting. The physical chirality is build into this very interface where chiral interaction is taking place. On a molecular level, soluble proteins in particul...

  10. Chiral separation in microflows

    OpenAIRE

    Kostur, Marcin; Schindler, Michael; Talkner, Peter; Hänggi, Peter

    2005-01-01

    Molecules that only differ by their chirality, so called enantiomers, often possess different properties with respect to their biological function. Therefore, the separation of enantiomers presents a prominent challenge in molecular biology and belongs to the ``Holy Grail'' of organic chemistry. We suggest a new separation technique for chiral molecules that is based on the transport properties in a microfluidic flow with spatially variable vorticity. Because of their size the thermal fluctua...

  11. Spontaneous chiral symmetry breaking in metamaterials

    Science.gov (United States)

    Liu, Mingkai; Powell, David A.; Shadrivov, Ilya V.; Lapine, Mikhail; Kivshar, Yuri S.

    2014-07-01

    Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.

  12. Thermo-sensitive spin valve based on layered artificial ferrimagnet

    Science.gov (United States)

    Svalov, A. V.; Kurlyandskaya, G. V.; Vas'kovskiy, V. O.

    2016-02-01

    In this work, the temperature and magnetic field dependences of magnetic and magnetoresistive properties of Gd-Co/Co/Cu/Co spin valves were comparatively analyzed. It was observed that the Gd-Co/Co bilayer structure exhibited macroscopic ferrimagnetic behavior. It was shown that the temperature dependence of magnetization of Gd-Co/Co layered artificial ferrimagnet could be the basis for the creation of a thermo-sensitive spin valve.

  13. A Dual Modulated Homochiral Helical Nanofilament Phase with Local Columnar Ordering Formed by Bent Core Liquid Crystals: Effects of Molecular Chirality.

    Science.gov (United States)

    Li, Lin; Salamonczyk, Miroslaw; Jákli, Antal; Hegmann, Torsten

    2016-08-01

    Helical nanofilament (HNF) phases form as a result of an intralayer mismatch between top and bottom molecular halves in bent-core liquid crystals (BC-LCs) that is relieved by local saddle-splay geometry. HNFs are immensely attractive for photovoltaic and chiral separation applications and as templates for the chiral spatial assembly of guest molecules. Here, the synthesis and characterization of two unichiral BC-LCs and one racemic mixture with tris-biphenyl-diester cores featuring chiral (R,R) and (S,S) or racemic 2-octyloxy aliphatic side chains are presented. In comparison to the achiral compound with linear side chains forming an intralayer modulated HNF phase (HNFmod ), synchrotron small angle X-ray diffraction indicates that the unichiral derivatives form a dual modulated HNF phase with intra- as well as interlayer modulations (HNFmod2 ) suggesting a columnar local structure of the nanofilaments. Transmission electron microscopy and circular dichroism spectropolarimetry confirm that the unichiral materials exclusively form homochiral HNFs with a twist sense-matching secondary twist. A contact preparation provides the first example of two identical chiral liquid crystal phases only differing in their handedness that do not mix and form an achiral liquid crystal phase with an entirely different structure in the contact zone. PMID:27334846

  14. Chiral separation of asenapine enantiomers by capillary electrophoresis and characterization of cyclodextrin complexes by NMR spectroscopy, mass spectrometry and molecular modeling.

    Science.gov (United States)

    Szabó, Zoltán-István; Tóth, Gergő; Völgyi, Gergely; Komjáti, Balázs; Hancu, Gabriel; Szente, Lajos; Sohajda, Tamás; Béni, Szabolcs; Muntean, Daniela-Lucia; Noszál, Béla

    2016-01-01

    The enantiomers of asenapine maleate (ASN), a novel antipsychotic against schizophrenia and mania with bipolar I disorder have been separated by cyclodextrin (CD) modified capillary zone electrophoresis for the first time. 15 different CDs were screened as complexing agents and chiral selectors, investigating the stability of the inclusion complexes and their enantiodiscriminating capacities. Although initially, none of the applied chiral selectors gave baseline separation, β-CD proved to be the most effective chiral selector. In order to improve resolution, an orthogonal experimental design was employed, altering the concentration of background electrolyte, organic modifier, pH, capillary temperature and applied voltage in a multivariate manner. The developed method (160 mM TRIS-acetate buffer pH 3.5, 7 mM β-CD, at 20 °C, applying 15 kV) was successful for baseline separation of ASN enantiomers (R(s)=2.40±0.04). Our method was validated according to ICH guidelines and proved to be sensitive, linear, accurate and precise for the chiral separation of ASN. Properties of the inclusion complexes, such as stoichiometry, atomic level intermolecular host-guest connections are proposed on the basis of ROESY NMR measurement, ESI-MS spectrometry and molecular modeling studies. It was found that the ASN-β-CD complex is of 1:1 composition, and either of the aromatic rings can be accommodated in the β-CD cavity. PMID:26440287

  15. The quest for chirality

    Energy Technology Data Exchange (ETDEWEB)

    Bonner, W.A. [Department of Chemistry Stanford University, Stanford, California 94305 (United States)

    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)

  16. Chiral Electronics

    OpenAIRE

    Kharzeev, Dmitri E.; Yee, Ho-Ung

    2012-01-01

    We consider the properties of electric circuits involving Weyl semimetals. The existence of the anomaly-induced chiral magnetic current in a Weyl semimetal subjected to magnetic field causes an interesting and unusual behavior of such circuits. We consider two explicit examples: i) a circuit involving the "chiral battery" and ii) a circuit that can be used as a "quantum amplifier" of magnetic field. The unique properties of these circuits stem from the chiral anomaly and may be utilized for c...

  17. Chiral photochemistry

    CERN Document Server

    Inoue, Yoshihisa

    2004-01-01

    Direct Asymmetric Photochemistry with Circularly Polarized Light, H. RauCoherent Laser Control of the Handedness of Chiral Molecules, P. Brumer and M. ShapiroMagnetochiral Anisotropy in Asymmetric Photochemistry, G.L.J.A.RikkenEnantiodifferentiating Photosensitized Reactions, Y. InoueDiastereodifferentiating Photoreactions, N. Hoffmann and J.-P. PeteChirality in Photochromism, Y. Yokoyama and M. SaitoChiral Photochemistry with Transition Metal Complexes, S. Sakaki and T. HamadaTemplate-Induced Enantioselective Photochemical Reactions in S

  18. Liquid chromatography with mass spectrometry enantioseparation of pomalidomide on cyclodextrin-bonded chiral stationary phases and the elucidation of the chiral recognition mechanisms by NMR spectroscopy and molecular modeling.

    Science.gov (United States)

    Szabó, Zoltán-István; Szőcs, Levente; Horváth, Péter; Komjáti, Balázs; Nagy, József; Jánoska, Ádám; Muntean, Daniela-Lucia; Noszál, Béla; Tóth, Gergő

    2016-08-01

    A sensitive and validated liquid chromatography with mass spectrometry method was developed for the enantioseparation of the racemic mixture of pomalidomide, a novel, second-generation immunomodulatory drug, using β-cyclodextrin-bonded stationary phases. Four cyclodextrin columns (β-, hydroxypropyl-β-, carboxymethyl-β-, and sulfobutyl-β-cyclodextrin) were screened and the effects of eluent composition, flow rate, temperature, and organic modifier on enantioseparation were studied. Optimized parameters, offering baseline separation (resolution = 2.70 ± 0.02) were the following: β-cyclodextrin stationary phase, thermostatted at 15°C, and mobile phase consisting of methanol/0.1% acetic acid 10:90 v/v, delivered with 0.8 mL/min flow rate. For the optimized parameter at multiple reaction monitoring mode 274.1-201.0 transition with 20 eV collision energy and 100 V fragmentor voltage the limit of detection and limit of quantitation were 0.75 and 2.00 ng/mL, respectively. Since enantiopure standards were not available, elution order was determined upon comparison of the circular dichroism signals of the separated pomalidomide enantiomers with that of enantiopure thalidomide. The mechanisms underlying the chiral discrimination between the enantiomers were also investigated. Pomalidomide-β-cyclodextrin inclusion complex was characterized using nuclear magnetic resonance spectroscopy and molecular modeling. The thermodynamic aspects of chiral separation were also studied. PMID:27279456

  19. Liquid chromatography with mass spectrometry enantioseparation of pomalidomide on cyclodextrin-bonded chiral stationary phases and the elucidation of the chiral recognition mechanisms by NMR spectroscopy and molecular modeling.

    Science.gov (United States)

    Szabó, Zoltán-István; Szőcs, Levente; Horváth, Péter; Komjáti, Balázs; Nagy, József; Jánoska, Ádám; Muntean, Daniela-Lucia; Noszál, Béla; Tóth, Gergő

    2016-08-01

    A sensitive and validated liquid chromatography with mass spectrometry method was developed for the enantioseparation of the racemic mixture of pomalidomide, a novel, second-generation immunomodulatory drug, using β-cyclodextrin-bonded stationary phases. Four cyclodextrin columns (β-, hydroxypropyl-β-, carboxymethyl-β-, and sulfobutyl-β-cyclodextrin) were screened and the effects of eluent composition, flow rate, temperature, and organic modifier on enantioseparation were studied. Optimized parameters, offering baseline separation (resolution = 2.70 ± 0.02) were the following: β-cyclodextrin stationary phase, thermostatted at 15°C, and mobile phase consisting of methanol/0.1% acetic acid 10:90 v/v, delivered with 0.8 mL/min flow rate. For the optimized parameter at multiple reaction monitoring mode 274.1-201.0 transition with 20 eV collision energy and 100 V fragmentor voltage the limit of detection and limit of quantitation were 0.75 and 2.00 ng/mL, respectively. Since enantiopure standards were not available, elution order was determined upon comparison of the circular dichroism signals of the separated pomalidomide enantiomers with that of enantiopure thalidomide. The mechanisms underlying the chiral discrimination between the enantiomers were also investigated. Pomalidomide-β-cyclodextrin inclusion complex was characterized using nuclear magnetic resonance spectroscopy and molecular modeling. The thermodynamic aspects of chiral separation were also studied.

  20. Molecular orientation behavior of chiral nematic liquid crystals based on the presence of blue phases using polarized microscopic FT-IR spectroscopy

    Science.gov (United States)

    Matsumura, Masanori; Katayama, Norihisa

    2016-07-01

    Study on molecular orientation behavior of highly twisted chiral nematic liquid crystals (N∗LCs) expressing blue phases (BPs) is important for developing new devices. This study examines the change of molecular orientation of N∗LCs due to the presence of BPs. Polarized microscopic FT-IR spectroscopy was used to study the in- and out-of-plane molecular orientations of N∗LCs that undergo a phase transition involving BPs. The band intensity ratio of CN to CH2 stretching modes (CN/CH2) in the IR spectra was used to determine the orientation of N∗LC molecules. The measured spectra indicated that the helical axis of N∗LC molecules was perpendicular to the substrate before heating and inclined on the substrate after cooling the sample which has phase transition from BP I to chiral nematic (N∗). The N∗LC molecule in the cell of rubbed orientation film exhibited the in-plane anisotropy after a heating-cooling ramp only in samples that passed through BP I. These results indicate that the changes of molecular orientation of N∗LC by phase transition are affected by BP I.

  1. Existence of solutions for the dynamic equation of ferrimagnets

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ferrimagnet is a kind of basic and important multi-sublattice magnet material. It has attracted more and more attention of physicists and mathematicians. Many results of solitons and numerical computations on this topic have appeared. In this article, the dynamic equation for an isotropic ferrimagnet with two non-equivalent sublattices is studied, existence of weak solutions in multi dimension case is proved through the penalized method, the uniqueness and smoothness of the solution in one dimension case are also obtained by the relation between this equation and hyperbolic equation.

  2. On superconductivity of matter at hight density and the effects of inducing nuclear chirality in molecular structures

    DEFF Research Database (Denmark)

    da Providëncia, J.; Jalkanen, Karl J.; Bohr, Henrik

    2013-01-01

    as they possibly relate to chirality of nuclei (atoms) in molecules as a source of chirality in amino acids and hence in life. Previous works have not investigated the nuclear forces as a possible bias which initiated the bias towards L-amino acids as the building blocks on proteins, and later life.......Superconductivity is described by the well-known Bardeen-Cooper-Schrieffer (BCS) theory, which is a symmetry breaking approximation. Color superconductivity shows up in extremely high density matter and temperature, which is here investigated and compared to the other end of the scale of low energy...

  3. Chirality and Life

    Science.gov (United States)

    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.

  4. Giant orthorhombic distortions by Cu+ in ferrimagnetic spinel Mn334

    Science.gov (United States)

    Chung, Jae-Ho; Lee, Kee Hwan; Chang, Hun; Hwang, In Yong; Kang, Hyun Wook; Kim, Su Jae; Lee, Seongsu

    2015-03-01

    Mn3O4 is a tetragonal (c > a) spinel that exhibits noncollinear Yafet-Kittel ferrimagnetic ordering at low temperatures. We report large orthorhombic distortions in its ferrimagnetic phase stabilized by a few percent of Cu doping. The orthorhombic strains of the ferrimagnetic phases increased linearly to the doping and reached up to ɛ ~ 8 . 2 ×10-3 for x = 0.19, which is three times larger than the saturated value under external magnetic fields. For high doping (xagt 0 . 17), the distortions first appeared in the paramagnetic phases and underwent further enhancement simultaneously with the onset of the noncollinear ferrimagnetic ordering. We present the rich magnetostructural phase diagram of CuxMn3-xO4, and argue that the diluted t2 orbital degeneracy of Cu2+ under tetrahedral crystal field breaks the global symmetry and triggers the orthorhombic instability inherent in Mn3O4. This work was supported by the National Research Foundation of Korea through the ARCNEX (NRF-2011-0031933).

  5. Stereodirection of an α-ketoester at sub-molecular sites on chirally modified Pt(111): Heterogeneous asymmetric catalysis

    DEFF Research Database (Denmark)

    Demers-Carpentier, V.; Rasmussen, A.M.H.; Goubert, G.;

    2013-01-01

    Chirally modified Pt catalysts are used in the heterogeneous asymmetric hydrogenation of α-ketoesters. Stereoinduction is believed to occur through the formation of chemisorbed modifier–substrate complexes. In this study, the formation of diastereomeric complexes by coadsorbed methyl 3,3,3-triflu...

  6. When did Louis Pasteur present his memoir on the discovery of molecular chirality to the Académie des sciences? Analysis of a discrepancy.

    Science.gov (United States)

    Gal, Joseph

    2008-11-01

    Louis Pasteur presented his historic memoir on the discovery of molecular chirality to the Académie des sciences in Paris on May 22nd, 1848. The literature, however, nearly completely ignores this date, widely claiming instead May 15th, 1848, which first surfaced in 1922 in Pasteur's collected works edited by his grandson Louis Pasteur Vallery-Radot. On May 21st, 1848, i.e., one day before Pasteur's presentation in Paris, his mother died in Arbois, eastern France. Informed at an unknown point in time that she was "very ill," Pasteur left for Arbois only after his presentation. Biographies of Pasteur by his son-in-law René Vallery-Radot or the grandson, and Pasteur's collected correspondence edited by the grandson are incomprehensibly laconic or silent about the historic presentation. While no definite conclusions are possible, the evidence strongly suggests a deliberate alteration of the record by the biographer relatives, presumably for fear of adverse public judgment of Pasteur for a real or perceived insensitivity to a grave family medical emergency. Such fear would have been in accord with their hagiographic portrayal of Pasteur, and the findings raise questions concerning the extent of their zeal in protecting his "demigod" image. Universal recognition of the true date of Pasteur's announcement of molecular chirality is long overdue.

  7. Isotopic chirality

    Energy Technology Data Exchange (ETDEWEB)

    Floss, H.G. [Univ. of Washington, Seattle, WA (United States)

    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.

  8. Chiral Superconductors

    OpenAIRE

    Kallin, Catherine; Berlinsky, John

    2015-01-01

    Chiral superconductivity is a striking quantum phenomenon in which an unconventional superconductor spontaneously develops an angular momentum and lowers its free energy by eliminating nodes in the gap. It is a topologically non-trivial state and, as such, exhibits distinctive topological modes at surfaces and defects. In this paper we discuss the current theory and experimental results on chiral superconductors, focusing on two of the best-studied systems, Sr2RuO4, which is thought to be a c...

  9. Mechanism of chirality conversion by periodic change of temperature: Role of chiral clusters

    Science.gov (United States)

    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.

  10. Possible $D\\bar{D}$ and $B\\bar{B}$ Molecular states in a chiral quark model

    CERN Document Server

    Li, M T; Dong, Y B; Zhang, Z Y

    2012-01-01

    We perform a systematic study of the bound state problem of $D\\bar{D}$ and $B\\bar{B}$ systems by using effective interaction in our chiral quark model. Our results show that both the interactions of $D\\bar{D}$ and $B\\bar{B}$ states are attractive, which consequently result in $I^G(J^{PC})=0^+(0^{++})$ $D\\bar{D}$ and $B\\bar{B}$ bound states.

  11. Origin of the spin Seebeck effect in compensated ferrimagnets

    Science.gov (United States)

    Geprägs, Stephan; Kehlberger, Andreas; Coletta, Francesco Della; Qiu, Zhiyong; Guo, Er-Jia; Schulz, Tomek; Mix, Christian; Meyer, Sibylle; Kamra, Akashdeep; Althammer, Matthias; Huebl, Hans; Jakob, Gerhard; Ohnuma, Yuichi; Adachi, Hiroto; Barker, Joseph; Maekawa, Sadamichi; Bauer, Gerrit E. W.; Saitoh, Eiji; Gross, Rudolf; Goennenwein, Sebastian T. B.; Kläui, Mathias

    2016-02-01

    Magnons are the elementary excitations of a magnetically ordered system. In ferromagnets, only a single band of low-energy magnons needs to be considered, but in ferrimagnets the situation is more complex owing to different magnetic sublattices involved. In this case, low lying optical modes exist that can affect the dynamical response. Here we show that the spin Seebeck effect (SSE) is sensitive to the complexities of the magnon spectrum. The SSE is caused by thermally excited spin dynamics that are converted to a voltage by the inverse spin Hall effect at the interface to a heavy metal contact. By investigating the temperature dependence of the SSE in the ferrimagnet gadolinium iron garnet, with a magnetic compensation point near room temperature, we demonstrate that higher-energy exchange magnons play a key role in the SSE.

  12. Influence of Chirality of Crizotinib on Its MTH1 Protein Inhibitory Activity: Insight from Molecular Dynamics Simulations and Binding Free Energy Calculations.

    Directory of Open Access Journals (Sweden)

    Yuzhen Niu

    Full Text Available As a promising target for the treatment of lung cancer, the MutT Homolog 1 (MTH1 protein can be inhibited by crizotinib. A recent work shows that the inhibitory potency of (S-crizotinib against MTH1 is about 20 times over that of (R-crizotinib. But the detailed molecular mechanism remains unclear. In this study, molecular dynamics (MD simulations and free energy calculations were used to elucidate the mechanism about the effect of chirality of crizotinib on the inhibitory activity against MTH1. The binding free energy of (S-crizotinib predicted by the Molecular Mechanics/Generalized Born Surface Area (MM/GBSA and Adaptive biasing force (ABF methodologies is much lower than that of (R-crizotinib, which is consistent with the experimental data. The analysis of the individual energy terms suggests that the van der Waals interactions are important for distinguishing the binding of (S-crizotinib and (R-crizotinib. The binding free energy decomposition analysis illustrated that residues Tyr7, Phe27, Phe72 and Trp117 were important for the selective binding of (S-crizotinib to MTH1. The adaptive biasing force (ABF method was further employed to elucidate the unbinding process of (S-crizotinib and (R-crizotinib from the binding pocket of MTH1. ABF simulation results suggest that the reaction coordinates of the (S-crizotinib from the binding pocket is different from (R-crizotinib. The results from our study can reveal the details about the effect of chirality on the inhibition activity of crizotinib to MTH1 and provide valuable information for the design of more potent inhibitors.

  13. Artificially engineered Heusler ferrimagnetic superlattice exhibiting perpendicular magnetic anisotropy

    OpenAIRE

    Q. L. Ma; Zhang, X. M.; Miyazaki, T.; Mizukami, S.

    2015-01-01

    To extend density limits in magnetic recording industry, two separate strategies were developed to build the storage bit in last decade, introduction of perpendicular magnetic anisotropy (PMA) and adoption of ferrimagnetism/antiferromagnetism. Meanwhile, these properties significantly improve device performance, such as reducing spin-transfer torque energy consumption and decreasing signal-amplitude-loss. However, materials combining PMA and antiferromagnetism rather than transition-metal/rar...

  14. Magnetostatic interactions in artificial ferrimagnet based magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Tiusan, C.; Dimopoulos, T.; Buda, L.; Da Costa, V.; Ounadjela, K.; Hehn, M.; van den Berg, H.

    2001-06-01

    Magnetostatic interactions between the soft and the hard magnetic electrodes in magnetic tunnel junctions (MTJs) using artificial ferrimagnets (AFis) are analyzed. We attribute these interactions to the dispersion fields associated to magnetic inhomogeneities arising from domain walls due to local anisotropic ordering. These magnetostatic interactions can be controlled by adjusting the net magnetic moment of the AFi to optimize the magnetotransport response of the MTJ devices.{copyright} 2001 American Institute of Physics.

  15. Chiral symmetry

    CERN Document Server

    Ecker, G

    1999-01-01

    Broken chiral symmetry has become the basis for a unified treatment of hadronic interactions at low energies. After reviewing mechanisms for spontaneous chiral symmetry breaking, I outline the construction of the low--energy effective field theory of the Standard Model called chiral perturbation theory. The loop expansion and the renormalization procedure for this nonrenormalizable quantum field theory are developed. Evidence for the standard scenario with a large quark condensate is presented, in particular from high--statistics lattice calculations of the meson mass spectrum. Elastic pion--pion scattering is discussed as an example of a complete calculation to O(p^6) in the low--energy expansion. The meson--baryon system is the subject of the last lecture. After a short summary of heavy baryon chiral perturbation theory, a recent analysis of pion--nucleon scattering to O(p^3) is reviewed. Finally, I describe some very recent progress in the chiral approach to the nucleon--nucleon interaction.

  16. Punctuated Chirality

    Science.gov (United States)

    Gleiser, Marcelo; Thorarinson, Joel; Walker, Sara Imari

    2008-12-01

    Most biomolecules occur in mirror, or chiral, images of each other. However, life is homochiral: proteins contain almost exclusively L-amino acids, while only D-sugars appear in RNA and DNA. The mechanism behind this fundamental asymmetry of life remains an open problem. Coupling the spatiotemporal evolution of a general autocatalytic polymerization reaction network to external environmental effects, we show through a detailed statistical analysis that high intensity and long duration events may drive achiral initial conditions towards chirality. We argue that life’s homochirality resulted from sequential chiral symmetry breaking triggered by environmental events, thus extending the theory of punctuated equilibrium to the prebiotic realm. Applying our arguments to other potentially life-bearing planetary platforms, we predict that a statistically representative sampling will be racemic on average.

  17. Punctuated Chirality

    CERN Document Server

    Gleiser, Marcelo; Walker, Sara Imari

    2008-01-01

    Most biomolecules occur in mirror, or chiral, images of each other. However, life is homochiral: proteins contain almost exclusively levorotatory (L) amino acids, while only dextrorotatory (R) sugars appear in RNA and DNA. The mechanism behind this fundamental asymmetry of life remains an open problem. Coupling the spatiotemporal evolution of a general autocatalytic polymerization reaction network to external environmental effects, we show through a detailed statistical analysis that high intensity and long duration events may drive achiral initial conditions towards chirality. We argue that life's homochirality resulted from sequential chiral symmetry breaking triggered by environmental events, thus extending the theory of punctuated equilibrium to the prebiotic realm. Applying our arguments to other potentially life-bearing planetary platforms, we predict that a statistically representative sampling will be racemic on average.

  18. Laser Writing of Multiscale Chiral Polymer Metamaterials

    Directory of Open Access Journals (Sweden)

    E. P. Furlani

    2012-01-01

    Full Text Available A new approach to metamaterials is presented that involves laser-based patterning of novel chiral polymer media, wherein chirality is realized at two distinct length scales, intrinsically at the molecular level and geometrically at a length scale on the order of the wavelength of the incident field. In this approach, femtosecond-pulsed laser-induced two-photon lithography (TPL is used to pattern a photoresist-chiral polymer mixture into planar chiral shapes. Enhanced bulk chirality can be realized by tuning the wavelength-dependent chiral response at both the molecular and geometric level to ensure an overlap of their respective spectra. The approach is demonstrated via the fabrication of a metamaterial consisting of a two-dimensional array of chiral polymer-based L-structures. The fabrication process is described and modeling is performed to demonstrate the distinction between molecular and planar geometric-based chirality and the effects of the enhanced multiscale chirality on the optical response of such media. This new approach to metamaterials holds promise for the development of tunable, polymer-based optical metamaterials with low loss.

  19. Molecular modeling of the binding mode of chiral metal complexes A- and A-[Co(phen)2dppz]3+ with B-DNA

    Institute of Scientific and Technical Information of China (English)

    杨频; 韩大雄

    2000-01-01

    Molecular modeling methods have been applied to the structural characterization of the interaction between chiral metal complexes [Co(phen)2dppz]3+ (where phen = 1, 10-phenanthroline, dppz = dipyrido[3,2-a: 2’, 3’-c]phenazine) and the oligonucleotide (B-DNA fragment). The natures of two kinds of the binding modes, which are currently intense controversy, have been explored. Barton proposed that there is enantio-selective DMA binding by the octahedral complexes and intercalative access by these complexes from the major groove; but Norden suggested that both enantiomers bind extremely strongly to DNA from the minor groove without any noticeable enantio-selectivity. Our results support and extend structural models based upon Norden’s studies, and conflict with Barton’s model.

  20. Molecular modeling of the binding mode of chiral metal complexes △- and (A)-[Co(phen)2dppz]3+ with B-DNA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Molecular modeling methods have been applied to the structural characterization of the interaction between chiral metal complexes [Co(phen)2dppz]3+ (where phen = 1, 10-phenanthroline, dppz = dipyrido[3,2-a: 2′, 3′-c]phenazine) and the oligonucleotide (B-DNA fragment). The natures of two kinds of the binding modes, which are currently intense controversy, have been explored. Barton proposed that there is enantio-selective DNA binding by the octahedral complexes and intercalative access by these complexes from the major groove; but Norden suggested that both enantiomers bind extremely strongly to DNA from the minor groove without any noticeable enantio-selectivity. Our results support and extend structural models based upon Norden's studies, and conflict with Barton's model.

  1. Anomalous Hall effect in epitaxial ferrimagnetic anti-perovskite Mn4-xDyxN films

    Science.gov (United States)

    Meng, M.; Wu, S. X.; Zhou, W. Q.; Ren, L. Z.; Wang, Y. J.; Wang, G. L.; Li, S. W.

    2015-08-01

    Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn4-xDyxN films grown by molecular-beam epitaxy. The introduction of Dy changes the AHE dramatically, even changes its sign, while the variations in magnetization are negligible. Two sign reversals of the AHE (negative-positive-negative) are ascribed to the variation of charge carriers as a result of Fermi surface reconstruction. We further demonstrate that the AHE current JAH is dissipationless (independent of the scattering rate), by confirming that anomalous Hall conductivity, σAH, is proportional to the carrier density n at 5 K. Our study may provide a route to further utilize antiperovskite manganese nitrides in spintronics.

  2. Large Enhancement of Circular Dichroism Using an Embossed Chiral Metamaterial

    CERN Document Server

    Mousavi, S Hamed Shams; El-Sayed, Mostafa A; Eftekhar, Ali A; Adibi, Ali

    2016-01-01

    In the close vicinity of a chiral nanostructure, the circular dichroism of a biomolecule could be greatly enhanced, due to the interaction with the local superchiral fields. Modest enhancement of optical activity using a planar metamaterial, with some chiral properties, and achiral nanoparticles has been previously reported. A more substantial chirality enhancement can be achieved in the local filed of a chiral nanostructure with a three-dimensional arrangement. Using an embossed chiral nanostructure designed for chiroptical sensing, we measure the circular dichroism spectra of two biomolecules, Chlorophylls A and B, at the molecular level, using a simple polarization resolved reflection measurement. This experiment is the first realization of the on-resonance surface-enhanced circular dichroism, achieved by matching the chiral resonances of a strongly chiral metamaterial with that of a chiral molecule, resulting in an unprecedentedly large differential CD spectrum from a monolayer of a chiral material.

  3. On Chiral Space Groups and Chiral Molecules

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This note explains the relationship (as well as the absence of a relationship) between chiral space groups and chiral molecules (which have absolute configurations). For a chiral molecule, which must crystallize in a chiral space group, the outcome of the absolute configuration determination must be linked to some other properties of the chiral crystal such as its optical activity for the observation to the relevant.

  4. In vitro DNA binding, pBR322 plasmid cleavage and molecular modeling study of chiral benzothiazole Schiff-base-valine Cu(II) and Zn(II) complexes to evaluate their enantiomeric biological disposition for molecular target DNA.

    Science.gov (United States)

    Alizadeh, Rahman; Afzal, Mohd; Arjmand, Farukh

    2014-10-15

    Bicyclic heterocyclic compounds viz. benzothiazoles are key components of deoxyribonucleic acid (DNA) molecules and participate directly in the encoding of genetic information. Benzothiazoles, therefore, represent a potent and selective class of antitumor compounds. The design and synthesis of chiral antitumor chemotherapeutic agents of Cu(II) and Zn(II), L- and -D benzothiazole Schiff base-valine complexes 1a &b and 2a &b, respectively were carried out and thoroughly characterized by spectroscopic and analytical techniques. Interaction of 1a and b and 2a and b with CT DNA by employing UV-vis, florescence, circular dichroic methods and cleavage studies of 1a with pBR322 plasmid, molecular docking were done in order to demonstrate their enantiomeric disposition toward the molecular drug target DNA. Interestingly, these studies unambiguously demonstrated the greater potency of L-enantiomer in comparison to D-enantiomer.

  5. In vitro DNA binding, pBR322 plasmid cleavage and molecular modeling study of chiral benzothiazole Schiff-base-valine Cu(II) and Zn(II) complexes to evaluate their enantiomeric biological disposition for molecular target DNA

    Science.gov (United States)

    Alizadeh, Rahman; Afzal, Mohd; Arjmand, Farukh

    2014-10-01

    Bicyclic heterocyclic compounds viz. benzothiazoles are key components of deoxyribonucleic acid (DNA) molecules and participate directly in the encoding of genetic information. Benzothiazoles, therefore, represent a potent and selective class of antitumor compounds. The design and synthesis of chiral antitumor chemotherapeutic agents of Cu(II) and Zn(II), L- and -D benzothiazole Schiff base-valine complexes 1a &b and 2a &b, respectively were carried out and thoroughly characterized by spectroscopic and analytical techniques. Interaction of 1a and b and 2a and b with CT DNA by employing UV-vis, florescence, circular dichroic methods and cleavage studies of 1a with pBR322 plasmid, molecular docking were done in order to demonstrate their enantiomeric disposition toward the molecular drug target DNA. Interestingly, these studies unambiguously demonstrated the greater potency of L-enantiomer in comparison to D-enantiomer.

  6. Spin-Orbital Superstructure in Strained Ferrimagnetic Perovskite Cobalt Oxide

    Science.gov (United States)

    Fujioka, J.; Yamasaki, Y.; Nakao, H.; Kumai, R.; Murakami, Y.; Nakamura, M.; Kawasaki, M.; Tokura, Y.

    2013-07-01

    We have investigated the Co-3d spin-orbital state in a thin film of perovskite LaCoO3 to clarify the origin of strain induced spontaneous magnetization (TC=94K) by means of x-ray diffraction, optical spectroscopy, and magnetization measurements. A lattice distortion with the propagation vector (1/4 -​​1/4 1/4) and an anomalous activation of optical phonons coupled to Co-3d orbital are observed below 126 K. Combined with the azimuthal angle analysis of superlattice reflection, we propose that the ordering of Co-3d orbital promoted by an epitaxial strain produces a unique ferrimagnetic structure.

  7. Punctuated Chirality

    OpenAIRE

    Gleiser, Marcelo; Thorarinson, Joel; Walker, Sara Imari

    2008-01-01

    Most biomolecules occur in mirror, or chiral, images of each other. However, life is homochiral: proteins contain almost exclusively levorotatory (L) amino acids, while only dextrorotatory (R) sugars appear in RNA and DNA. The mechanism behind this fundamental asymmetry of life remains an open problem. Coupling the spatiotemporal evolution of a general autocatalytic polymerization reaction network to external environmental effects, we show through a detailed statistical analysis that high int...

  8. Chiral streamers

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Dandan; Cao, Xin [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Lu, Xinpei, E-mail: luxinpei@hotmail.com [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Ostrikov, Kostya [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4000 (Australia); Comonwealth Scientific and Industrial Research Organization, P.O. Box 218, Sydney, New South Wales 2070 (Australia)

    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.

  9. Chiral streamers

    Science.gov (United States)

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

    2015-10-01

    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.

  10. Artificially engineered Heusler ferrimagnetic superlattice exhibiting perpendicular magnetic anisotropy

    Science.gov (United States)

    Ma, Q. L.; Zhang, X. M.; Miyazaki, T.; Mizukami, S.

    2015-01-01

    To extend density limits in magnetic recording industry, two separate strategies were developed to build the storage bit in last decade, introduction of perpendicular magnetic anisotropy (PMA) and adoption of ferrimagnetism/antiferromagnetism. Meanwhile, these properties significantly improve device performance, such as reducing spin-transfer torque energy consumption and decreasing signal-amplitude-loss. However, materials combining PMA and antiferromagnetism rather than transition-metal/rare-earth system were rarely developed. Here, we develop a new type of ferrimagnetic superlattice exhibiting PMA based on abundant Heusler alloy families. The superlattice is formed by [MnGa/Co2FeAl] unit with their magnetizations antiparallel aligned. The effective anisotropy (Kueff) over 6 Merg/cm3 is obtained, and the SL can be easily built on various substrates with flexible lattice constants. The coercive force, saturation magnetization and Kueff of SLs are highly controllable by varying the thickness of MnGa and Co2FeAl layers. The SLs will supply a new choice for magnetic recording and spintronics memory application such as magnetic random access memory.

  11. Atomic layer deposition of superparamagnetic and ferrimagnetic magnetite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yijun; Liu, Ming, E-mail: mingliu@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn, E-mail: zye@sfu.ca; Ren, Wei, E-mail: mingliu@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn, E-mail: zye@sfu.ca [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Yuepeng; Chen, Xing [Energy Systems Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States); Ye, Zuo-Guang, E-mail: mingliu@mail.xjtu.edu.cn, E-mail: wren@mail.xjtu.edu.cn, E-mail: zye@sfu.ca [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi' an Jiaotong University, Xi' an 710049 (China); Department of Chemistry and 4D LABS, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada)

    2015-05-07

    One of the key challenges in realizing superparamagnetism in magnetic thin films lies in finding a low-energy growth way to create sufficiently small grains and magnetic domains which allow the magnetization to randomly and rapidly reverse. In this work, well-defined superparamagnetic and ferrimagnetic Fe{sub 3}O{sub 4} thin films are successfully prepared using atomic layer deposition technique by finely controlling the growth condition and post-annealing process. As-grown Fe{sub 3}O{sub 4} thin films exhibit a conformal surface and poly-crystalline nature with an average grain size of 7 nm, resulting in a superparamagnetic behavior with a blocking temperature of 210 K. After post-annealing in H{sub 2}/Ar at 400 °C, the as-grown α−Fe{sub 2}O{sub 3} sample is reduced to Fe{sub 3}O{sub 4} phase, exhibiting a ferrimagnetic ordering and distinct magnetic shape anisotropy. Atomic layer deposition of magnetite thin films with well-controlled morphology and magnetic properties provides great opportunities for integrating with other order parameters to realize magnetic nano-devices with potential applications in spintronics, electronics, and bio-applications.

  12. Microwave assisted one-pot synthesis of novel molecular clefts with only one chiral arm based on deoxycholic acid

    Institute of Scientific and Technical Information of China (English)

    Bi Tao Zeng; Zhi Gang Zhao; Xing Li Liu; Yun Shi

    2008-01-01

    A rapid, safe, and efficient method for the synthesis of novel molecular clefts based" on deoxycholic acid was reported. Sevennew molecular clefts have been synthesized in good yields (89-98%). This method proved to be extremely simple and highlyefficient. The structures of these receptors were confirmed by 1H NMR, IR, MS spectra and elemental analysis.

  13. Direct chromatographic enantioresolution of fully constrained β-amino acids: exploring the use of high-molecular weight chiral selectors.

    Science.gov (United States)

    Sardella, Roccaldo; Ianni, Federica; Lisanti, Antonella; Scorzoni, Stefania; Marini, Francesca; Sternativo, Silvia; Natalini, Benedetto

    2014-05-01

    To the best of our knowledge enantioselective chromatographic protocols on β-amino acids with polysaccharide-based chiral stationary phases (CSPs) have not yet appeared in the literature. Therefore, the primary objective of this work was the development of chromatographic methods based on the use of an amylose derivative CSP (Lux Amylose-2), enabling the direct normal-phase (NP) enantioresolution of four fully constrained β-amino acids. Also, the results obtained with the glycopeptide-type Chirobiotic T column employed in the usual polar-ionic (PI) mode of elution are compared with those achieved with the polysaccharide-based phase. The Lux Amylose-2 column, in combination with alkyl sulfonic acid containing NP eluent systems, prevailed over the Chirobiotic T one, when used under the PI mode of elution, and hence can be considered as the elective choice for the enantioseparation of this class of rigid β-amino acids. Moreover, the extraordinarily high α (up to 4.60) and R S (up to 10.60) values provided by the polysaccharidic polymer, especially when used with camphor sulfonic acid containing eluent systems, make it also suitable for preparative-scale enantioisolations.

  14. Chiral geometry in multiple chiral doublet bands

    CERN Document Server

    Zhang, Hao

    2015-01-01

    The chiral geometry of the multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters $\\gamma$ in the particle rotor model with $\\pi h_{11/2}\\otimes \

  15. Evaluation of the effect of the chiral centers of Taxol on binding to β-tubulin: A docking and molecular dynamics simulation study.

    Science.gov (United States)

    Ghadari, Rahim; Alavi, Fatemeh S; Zahedi, Mansour

    2015-06-01

    Taxol is one of the most important anti-cancer drugs. The interaction between different variants of Taxol, by altering one of its chiral centers at a time, with β-tubulin protein has been investigated. To achieve such goal, docking and molecular dynamics (MD) simulation studies have been performed. In docking studies, the preferred conformers have been selected to further study by MD method based on the binding energies reported by the AutoDock program. The best result of docking study which shows the highest affinity between ligand and protein has been used as the starting point of the MD simulations. All of the complexes have shown acceptable stability during the simulation process, based on the RMSDs of the backbone of the protein structure. Finally, MM-GBSA calculations have been carried out to select the best ligand, considering the binding energy criteria. The results predict that two of the structures have better affinity toward the mentioned protein, in comparison with Taxol. Three of the structures have affinity similar to that of the Taxol toward the β-tubulin.

  16. Molecular modeling on the recognition of DNA sequence and conformational repair of sheared DNA by novel chiral metal complex D, L-[Co(phen)2hpip]3+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A study on the recognition of DNA sequence and conformational repair of sheared DNA by Novel Chiral Metal complex D,L-[Co(phen)2hpip]3+ (phen=1,10 phenanthroline, hpip=2-[2-hydroxyphenyl] imidazole [4,5-f][1,10] phenanthroline) is carried out with molecular simulations. The results reveal that two isomers of the complex could both recognize the normal DNA in the minor groove orientation, while recognize the sheared DNA in the major groove orientation and both isomers could convert the conformation of mismatched bases from sheared form to parallel form. Further analysis shows that the steric details of complex's intercalation to base stack determine the results of recognition, which is induced by the steric collision among ancillary ligand phen, bases and DNA backbone, and by the steric crowding occurring in the process of structural expansion of bases and DNA backbone. Detailed analysis reveals that the conformational repair of mismatched bases relates not only to the steric interactions, but also to the π-π stack among normal bases, mismatched bases and hpip ligand.

  17. Ferrimagnetism in MnxV1-x alloys

    International Nuclear Information System (INIS)

    Full text: The magnetic properties of MnV alloys near the equiatomic concentration have been investigated using magnetic susceptibility and neutron powder diffraction. Rapidly cooled body centred cubic alloys near the equiatomic concentration are confirmed as very weakly ferrimagnetic with average local moment of the order of 0.05 μB per atom and average ordered moments of order 0.02 μB per atom. The degree of atomic and magnetic order can be greatly enhanced by annealing these alloys supporting the view that the ordered moments are associated with CsCl type atomic short range order. Evidence is presented that the moment is not associated with impurities or any of the multitude of magnetically ordered mixed manganese vanadium oxides

  18. Detecting Chirality in Molecules by Linearly Polarized Laser Fields

    Science.gov (United States)

    Yachmenev, Andrey; Yurchenko, Sergei N.

    2016-07-01

    A new scheme for enantiomer differentiation of chiral molecules using a pair of linearly polarized intense ultrashort laser pulses with skewed mutual polarization is presented. The technique relies on the fact that the off-diagonal anisotropic contributions to the electric polarizability tensor for two enantiomers have different signs. Exploiting this property, we are able to excite a coherent unidirectional rotation of two enantiomers with a π phase difference in the molecular electric dipole moment. The approach is robust and suitable for relatively high temperatures of molecular samples, making it applicable for selective chiral analysis of mixtures, and to chiral molecules with low barriers between enantiomers. As an illustration, we present nanosecond laser-driven dynamics of a tetratomic nonrigid chiral molecule with short-lived chirality. The ultrafast time scale of the proposed technique is well suited to study parity violation in molecular systems in short-lived chiral states.

  19. Detecting chirality in molecules by linearly polarized laser fields

    CERN Document Server

    Yachmenev, Andrey

    2016-01-01

    A new scheme for enantiomer differentiation of chiral molecules using a pair of linearly polarized intense ultrashort laser pulses with skewed mutual polarization is presented. The technique relies on the fact that the off-diagonal anisotropic contributions to the electric polarizability tensor for two enantiomers have different signs. Exploiting this property, we are able to excite a coherent unidirectional rotation of two enantiomers with a {\\pi} phase difference in the molecular electric dipole moment. The approach is robust and suitable for relatively high temperatures of molecular samples, making it applicable for selective chiral analysis of mixtures, and to chiral molecules with low barriers between enantiomers. As an illustration, we present nanosecond laser-driven dynamics of a tetratomic non-rigid chiral molecule with short-lived chirality. The ultrafast time scale of the proposed technique is well suited to study parity violation in molecular systems in short-lived chiral states.

  20. Chiral recognition of Propranolol enantiomers by β-Cyclodextrin: Quantum chemical calculation and molecular dynamics simulation studies

    Energy Technology Data Exchange (ETDEWEB)

    Ghatee, Mohammad Hadi, E-mail: ghatee@susc.ac.ir; Sedghamiz, Tahereh

    2014-12-05

    Highlights: • Enantiomeric recognition of Propranolol studied by β-Cyclodextrin complexations. • Complexes characterized by PM3 and molecular dynamics (MD) simulation methods. • Results support more stability of R-enantiomer complex in gas and in aqueous solution phases. • Gas phase complexes are unlikely free-energy-wise, though solution phase’s are more likely. • Higher molecular diffusion in aqueous solution phase is inherent to S-enantiomer. - Abstract: Enantiomeric recognition of Propranolol by complexation with β-Cyclodextrin was studied by PM3 method and molecular dynamics (MD) simulation. Gas phase results show that the R-enantiomer complex is more stable than the S-enantiomer complex by 8.54 kJ/mol (Hartree–Fock energy). Using polarized continuum model, solution phase of R-enantiomer complex was found to be more stable than S-enantiomer complex by 25.95 kJ/mol. Both complexes hardly occur at room temperature free-energy-wise, though, complexation with R-enantiomer is more favorable than with S-enantiomer enthalpy-wise. Also, complexes were studied by molecular dynamics simulation in gas and solution phases. More stability of R-enantiomer complex in gas phase is confirmed by MD van der Waals energy (5.04 kJ/mol) and closely by the counterpart PM3 binding energy (8.54 kJ/mol). Simulation in solution phase indicates more stability of R-enantiomer complex. Finally, simulated transport property provides insight into the high anisotropic atoms motion according to which S-Propranolol found possessing significantly higher dynamics.

  1. Chiral mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Plum, Eric, E-mail: erp@orc.soton.ac.uk [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Zheludev, Nikolay I., E-mail: niz@orc.soton.ac.uk [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637378 (Singapore)

    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.

  2. Intelligent Chiral Sensing Based on Supramolecular and Interfacial Concepts

    Directory of Open Access Journals (Sweden)

    Hironori Izawa

    2010-07-01

    Full Text Available 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. Application of cyclodextrins in chiral capillary electrophoresis.

    Science.gov (United States)

    Rezanka, Pavel; Navrátilová, Klára; Rezanka, Michal; Král, Vladimír; Sýkora, David

    2014-10-01

    CE represents a very powerful separation tool in the area of chiral separations. CD-mediated chiral CE is a continuously flourishing technique within the frame of the electromigration methods. In this review, a brief overview of the synthetic procedures leading to modified CDs is provided first. Next, selected aspects related to the utilization of CDs in chiral CE are discussed specifically in the view of recently published data. Advantages of CDs and basic principles of chiral CE are remained. The topic of the determination of binding constants is touched. Particular attention is paid to the effort aiming at better understanding of the molecular level of the enantiorecognition between CDs and the analyte in the solution. Powerful approaches extensively utilized in this field are NMR, molecular modeling, and computer simulations. Then, a summary of applications of CDs in the CE enantioseparations is given, covering years 2008-2013. Finally, the general trend of modified CDs use in separation science is statistically evaluated.

  4. Ultrafast dynamical path for the switching of a ferrimagnet after femtosecond heating

    OpenAIRE

    Atxitia, U.; Ostler, T. A.; Barker, J; Evans, R F L; Chantrell, R W; Chubykalo-Fesenko, O.

    2013-01-01

    Ultrafast laser-induced magnetic switching in rare earth-transition metal ferrimagnetic alloys has recently been reported to occur by ultrafast heating alone. Using atomistic simulations and a ferrimagnetic Landau-Lifshitz-Bloch formalism, we demonstrate that for switching to occur it is necessary that angular momentum is transferred from the longitudinal to transverse magnetization components in the transition metal. This dynamical path leads to the transfer of the angular momentum to the ra...

  5. Chiral Gravitational Waves from Chiral Fermions

    CERN Document Server

    Anber, Mohamed M

    2016-01-01

    We report on a new mechanism that leads to the generation of primordial chiral gravitational waves, and hence, the violation of the parity symmetry in the Universe. We show that nonperturbative production of fermions with a definite helicity is accompanied by the generation of chiral gravitational waves. This is a generic and model-independent phenomenon that can occur during inflation, reheating and radiation eras, and can leave imprints in the cosmic microwave background polarization and may be observed in future ground- and space-based interferometers. We also discuss a specific model where chiral gravitational waves are generated via the production of light chiral fermions during pseudoscalar inflation.

  6. Transfer of chirality from adsorbed chiral molecules to the substrates highlighted by circular dichroism in angle-resolved valence photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Contini, G.; Turchini, S.; Sanna, Simone;

    2012-01-01

    state, that the presence of molecular chiral domains induces asymmetry in the interaction with the substrate and locally transfers the chiral character to the underlying metal atoms participating in the adsorption process; combined information related to the asymmetry of the initial electronic state......Studies of self-assembled chiral molecules on achiral metallic surfaces have mostly focused on the determination of the geometry of adsorbates and their electronic structure. The aim of this paper is to provide direct information on the chirality character of the system and on the chirality......, which is expected to be chiral, and the final electronic state, which locally probes the asymmetry of the potential, has been obtained. Identification of chirality in the adsorption footprint sheds new light on the transfer of chirality from a chiral modifier to a symmetric metal surface and represents...

  7. Large anomalous Hall effect in Pt interfaced with perpendicular anisotropy ferrimagnetic insulator

    Science.gov (United States)

    Tang, Chi; Sellappan, Pathikumar; Liu, Yawen; Garay, Javier; Shi, Jing; Shines Team

    We demonstrate the strain induced perpendicular magnetic anisotropy (PMA) in a ferrimagnetic insulator (FMI), Tm3Fe5O12 (TIG) and the first observation of large anomalous Hall effect (AHE) in TIG/Pt bilayers. Atomically flat TIG films were deposited by a laser molecular beam epitaxy system on (111)-orientated substituted gadolinium gallium garnet substrates. The strength of PMA could be effectively tuned by controlling the oxygen pressure during deposition. Sharp squared anomalous Hall hysteresis loops were observed in bilayers of TIG/Pt over a range of thicknesses of Pt, with the maximum AHE conductivity reaching 1 S/cm at room temperature. The AHE vanishes when a 5 nm Cu layer was inserted between Pt and TIG, strongly indicating the proximity-induced ferromagnetism in Pt. The large AHE in the bilayer structures demonstrates a potential use of PMA-FMI related heterostructures in spintronics. This work was supported as part of the SHINES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # SC0012670.

  8. In Vitro Evaluation of Some Types of Ferrimagnetic Glass Ceramics

    Directory of Open Access Journals (Sweden)

    S. A. M. Abdel-Hameed

    2014-01-01

    Full Text Available The present study aimed at studying the acceleration of the bioactive layer on the surface of ferrimagnetic glass ceramic with a basic composition 40Fe2O3–15P2O5–20SiO2–5TiO2 through the addition of 20% of different types of metal oxides like MgO or CaO or MnO or CuO or ZnO or CeO2. SEM, EDAX, and ICP were applied to present the results of the study. SEM and EDAX measurements indicated the presence of apatite layer formed on the surface of the prepared glass ceramics after immersion in SBF within 7 to 30 days. The investigation of the results clarified that the addition of CaO or ZnO accelerated the formation of apatite on the surfaces of the samples in the simulated body fluid faster than other metal oxides. Inductive coupled plasma (ICP analysis shows the evolution of ion extraction by the simulated body fluid solution (SBF with time in relation to the elemental composition.

  9. Engineered Heusler Ferrimagnets with a Large Perpendicular Magnetic Anisotropy

    Directory of Open Access Journals (Sweden)

    Reza Ranjbar

    2015-09-01

    Full Text Available Synthetic perpendicular magnetic anisotropy (PMA ferrimagnets consisting of 30-nm-thick D022-MnGa and Co2MnSi (CMS cubic Heusler alloys with different thicknesses of 1, 3, 5, 10 and 20 nm, buffered and capped with a Cr film, are successfully grown epitaxially on MgO substrate. Two series samples with and without post annealing at 400 °C are fabricated. The (002 peak of the cubic L21 structure of CMS films on the MnGa layer is observed, even for the 3-nm-thick CMS film for both un-annealed and annealed samples. The smaller remnant magnetization and larger switching field values of CMS (1–20 nm/MnGa (30 nm bilayers compared with 30-nm-thick MnGa indicates antiferromagnetic (AFM interfacial exchange coupling (Jex between MnGa and CMS films for both un-annealed and annealed samples. The critical thickness of the CMS film for observing PMA with AFM coupling in the CMS/MnGa bilayer is less than 10 nm, which is relatively large compared to previous studies.

  10. Anomalous Chiral Superfluidity

    OpenAIRE

    Lublinsky, Michael(Physics Department, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel); Zahed, Ismail

    2009-01-01

    We discuss both the anomalous Cartan currents and the energy-momentum tensor in a left chiral theory with flavour anomalies as an effective theory for flavored chiral phonons in a chiral superfluid with the gauged Wess-Zumino-Witten term. In the mean-field (leading tadpole) approximation the anomalous Cartan currents and the energy momentum tensor take the form of constitutive currents in the chiral superfluid state. The pertinence of higher order corrections and the Adler-Bardeen theorem is ...

  11. Baryons and Chiral Symmetry

    CERN Document Server

    Liu, Keh-Fei

    2016-01-01

    The relevance of chiral symmetry in baryons is highlighted in three examples in the nucleon spectroscopy and structure. The first one is the importance of chiral dynamics in understanding the Roper resonance. The second one is the role of chiral symmetry in the lattice calculation of $\\pi N \\sigma$ term and strangeness. The third one is the role of chiral $U(1)$ anomaly in the anomalous Ward identity in evaluating the quark spin and the quark orbital angular momentum. Finally, the chiral effective theory for baryons is discussed.

  12. On chiral and non chiral 1D supermultiplets

    Energy Technology Data Exchange (ETDEWEB)

    Toppan, Francesco, E-mail: toppan@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (TEO/CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Fisica Teorica

    2011-07-01

    In this talk I discuss and clarify some issues concerning chiral and non chiral properties of the one-dimensional supermultiplets of the N-extended supersymmetry. Quaternionic chirality can be defined for N = 4, 5, 6, 7, 8. Octonionic chirality for N = 8 and beyond. Inequivalent chiralities only arise when considering several copies of N = 4 or N = 8 supermultiplets. (author)

  13. Chiral symmetry and chiral-symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    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)

  14. Understanding complex chiral plasmonics

    Science.gov (United States)

    Duan, Xiaoyang; Yue, Song; Liu, Na

    2015-10-01

    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.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

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

    Science.gov (United States)

    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

  16. Chiral Superfluidity for QCD

    CERN Document Server

    Kalaydzhyan, Tigran

    2014-01-01

    We argue that the strongly coupled quark-gluon plasma formed at LHC and RHIC can be considered as a chiral superfluid. The "normal" component of the fluid is the thermalized matter in common sense, while the "superfluid" part consists of long wavelength (chiral) fermionic states moving independently. We use the bosonization procedure with a finite cut-off and obtain a dynamical axion-like field out of the chiral fermionic modes. Then we use relativistic hydrodynamics for macroscopic description of the effective theory obtained after the bosonization. Finally, solving the hydrodynamic equations in gradient expansion, we find that in the presence of external electromagnetic fields or rotation the motion of the "superfluid" component gives rise to the chiral magnetic, chiral vortical, chiral electric and dipole wave effects. Latter two effects are specific for a two-component fluid, which provides us with crucial experimental tests of the model.

  17. Mechanical separation of chiral dipoles by chiral light

    CERN Document Server

    Canaguier-Durand, Antoine; Genet, Cyriaque; Ebbesen, Thomas W

    2013-01-01

    Optical forces take on a specific form when involving chiral light fields interacting with chiral objects. We show that optical chirality density and flow can have mechanical effects through reactive and dissipative components of chiral forces exerted on chiral dipoles. Remarkably, these force components are directly related to standard observables: optical rotation and circular dichroism, respectively. As a consequence, resulting forces and torques are dependent on the enantiomeric form of the chiral dipole. This leads to promising strategies for the mechanical separation of chiral objects using chiral light forces.

  18. Fabrication of a Complex Two-Dimensional Adenine-Perylene-3,4,9, 10-tetracarboxylic Dianhydride Chiral Nanoarchitecture through Molecular Self-Assembly

    OpenAIRE

    Sun, Xiaonan; Mura, Manuela; Jonkman, Harry T.; Kantorovich, Lev N.; Silly, Fabien

    2012-01-01

    The two-dimensional self-assembly of a nonsyrnmetric adenine DNA base mixed with symmetric perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules is investigated using scanning tunneling microscopy (STM). We experimentally observe that these two building blocks form a complex close-packed chiral supramolecular network on Au(111). The unit cell of the adenine PTCDA nanoarchitecture is composed of 14 molecules. The high stability of this structure relies on PTCDA-PTCDA and PTCDA-adenin...

  19. Chiral atomically thin films

    Science.gov (United States)

    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. Anomalous chiral superfluidity

    Energy Technology Data Exchange (ETDEWEB)

    Lublinsky, Michael, E-mail: lublinsky@phys.uconn.ed [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States); Physics Department, Ben-Gurion University, Beer Sheva 84105 (Israel); Zahed, Ismail [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2010-02-08

    We discuss both the anomalous Cartan currents and the energy-momentum tensor in a left chiral theory with flavor anomalies as an effective theory for flavored chiral phonons in a chiral superfluid with the gauged Wess-Zumino-Witten term. In the mean-field (leading tadpole) approximation the anomalous Cartan currents and the energy-momentum tensor take the form of constitutive currents in the chiral superfluid state. The pertinence of higher order corrections and the Adler-Bardeen theorem is briefly noted.

  1. Chiral Shock Waves

    CERN Document Server

    Sen, Srimoyee

    2016-01-01

    We study shock waves in relativistic chiral matter. We argue that the conventional Rankine- Hugoinot relations are modified due to the presence of chiral transport phenomena. We show that the entropy discontinuity in a weak shock wave is linearly proportional to the pressure discontinuity when the effect of chiral transport becomes sufficiently large. We also show that rarefaction shock waves, which do not exist in usual nonchiral fluids, can appear in chiral matter. These features are exemplified by shock propagation in dense neutrino matter in the hydrodynamic regime.

  2. Doped Chiral Polymer Metamaterials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Doped Chiral Polymer Metamaterials (DCPM) with tunable resonance frequencies have been developed by adding plasmonic inclusions into chiral polymers with variable...

  3. Can circular dichroism in core-level photoemission provide a spectral fingerprint of adsorbed chiral molecules?

    Energy Technology Data Exchange (ETDEWEB)

    Allegretti, F [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom); Polcik, M [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D 14195 Berlin (Germany); Sayago, D I [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D 14195 Berlin (Germany); Demirors, F [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D 14195 Berlin (Germany); O' Brien, S [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom); Nisbet, G [Centre for Applied Catalysis, Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom); Lamont, C L A [Centre for Applied Catalysis, Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom); Woodruff, D P [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2005-04-01

    The results of experimental measurements and theoretical simulations of circular dichroism in the angular distribution (CDAD) of photoemission from atomic core levels of each of the enantiomers of a chiral molecule, alanine, adsorbed on Cu(1 1 0) are presented. Measurements in, and out of, substrate mirror planes allow one to distinguish the CDAD due to the chirality of the sample from that due to a chiral experimental geometry. For these studies of oriented chiral molecules, the CDAD is seen not only in photoemission from the molecular chiral centre, but also from other atoms which have chiral geometries as a result of the adsorption. The magnitude of the CDAD due to the sample chirality differs for different adsorption phases of alanine, and for different emission angles and energies, but is generally small compared with CDAD out of the substrate mirror planes which is largely unrelated to the molecular chirality. While similar measurements of other molecules may reveal larger CDAD due to molecular chirality, the fact that the results for one chiral molecule show weak effects means that such CDAD is unlikely to provide a simple and routine general spectral fingerprint of adsorbed molecular chirality.

  4. Origin of metallic behavior in NiCo2O4 ferrimagnet

    Science.gov (United States)

    Bitla, Yugandhar; Chin, Yi-Ying; Lin, Jheng-Cyuan; van, Chien Nguyen; Liu, Ruirui; Zhu, Yuanmin; Liu, Heng-Jui; Zhan, Qian; Lin, Hong-Ji; Chen, Chien-Te; Chu, Ying-Hao; He, Qing

    2015-10-01

    Predicting and understanding the cation distribution in spinels has been one of the most interesting problems in materials science. The present work investigates the effect of cation redistribution on the structural, electrical, optical and magnetic properties of mixed-valent inverse spinel NiCo2O4(NCO) thin films. It is observed that the films grown at low temperatures (T  400 °C) are insulators with lower ferrimagnetic-paramagnetic phase transition temperature. So far, n-type Fe3O4 has been used as a conducting layer for the spinel thin films based devices and the search for a p-type counterpart still remains elusive. The inherent coexistence and coupling of ferrimagnetic order and the metallic nature in p-type NCO makes it a promising candidate for spintronic devices. Detailed X-ray Absorption and X-ray Magnetic Circular Dichroism studies revealed a strong correlation between the mixed-valent cation distribution and the resulting ferrimagnetic-metallic/insulating behavior. Our study clearly demonstrates that it is the concentration of Ni3+ions and the Ni3+-O2-Ni2+ double exchange interaction that is crucial in dictating the metallic behavior in NCO ferrimagnet. The metal-insulator and the associated magnetic order-disorder transitions can be tuned by the degree of cation site disorder via growth conditions.

  5. Spin Canting and Transverse Relaxation at Surfaces and in the Interior of Ferrimagnetic Particles

    DEFF Research Database (Denmark)

    Mørup, Steen

    2003-01-01

    Analytical expressions for the magnetic energy and the spin-canting angles in some simple ferrimagnetic bulk and surface structures are presented. It is shown that the energy barriers separating different spin-canted states often will be very small. Therefore, the spin canting may be static only ...

  6. Direct observation of ferrimagnetic/ferroelastic domain interactions in magnetite below the Verwey transition

    DEFF Research Database (Denmark)

    Kasama, Takeshi; Church, Nathan S.; Feinberg, Joshua M.;

    2010-01-01

    The magnetic behaviour of magnetite at low temperatures is dominated by its transformation to a monoclinic crystal structure that is simultaneously ferrimagnetic, ferroelastic and ferroelectric below similar to 125 K (the Verwey transition). Here we use electron microscopy to reveal the relations...

  7. Ordered ferrimagnetic form of ferrihydrite reveals links among structure, composition, and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Michel, F. Marc; Barrón, Vidal; Torrent, José; Morales, María P.; Serna, Carlos J.; Boily, Jean-François; Liu, Qingsong; Ambrosini, Andrea; Cismasu, A. Cristina; Brown, Jr., Gordon E. (CSIC-Spain); (Stanford); (Sandia); (Cordoba); (Umea); (Chinese Aca. Sci.)

    2010-11-19

    The natural nanomineral ferrihydrite is an important component of many environmental and soil systems and has been implicated as the inorganic core of ferritin in biological systems. Knowledge of its basic structure, composition, and extent of structural disorder is essential for understanding its reactivity, stability, and magnetic behavior, as well as changes in these properties during aging. Here we investigate compositional, structural, and magnetic changes that occur upon aging of '2-line' ferrihydrite in the presence of adsorbed citrate at elevated temperature. Whereas aging under these conditions ultimately results in the formation of hematite, analysis of the atomic pair distribution function and complementary physicochemical and magnetic data indicate formation of an intermediate ferrihydrite phase of larger particle size with few defects, more structural relaxation and electron spin ordering, and pronounced ferrimagnetism relative to its disordered ferrihydrite precursor. Our results represent an important conceptual advance in understanding the nature of structural disorder in ferrihydrite and its relation to the magnetic structure and also serve to validate a controversial, recently proposed structural model for this phase. In addition, the pathway we identify for forming ferrimagnetic ferrihydrite potentially explains the magnetic enhancement that typically precedes formation of hematite in aerobic soil and weathering environments. Such magnetic enhancement has been attributed to the formation of poorly understood, nano-sized ferrimagnets from a ferrihydrite precursor. Whereas elevated temperatures drive the transformation on timescales feasible for laboratory studies, our results also suggest that ferrimagnetic ferrihydrite could form naturally at ambient temperature given sufficient time.

  8. Chiral geometry in multiple chiral doublet bands

    Science.gov (United States)

    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. Imprinting Chirality in Silica Nanotubes by N-Stearoyl-serine Template.

    Science.gov (United States)

    Levi, Gila; Scolnik, Yosef; Mastai, Yitzhak

    2016-09-01

    In this article, we describe the synthesis of imprinted chiral silica nanotubes based on the use of a chiral N-stearoyl l-serine (C18Ser) anionic surfactant as the chiral template. The resulting chiral silica nanotube structures were characterized by electronic microscopy (transmission electron microscopy (TEM) and scanning electron microscopy (SEM)) and nitrogen isotherms that proved the formation of well-ordered silica nanotubes. A C18Ser surfactant template was used for the preparation of the silica nanotubes, due to its effective molecular organization within the silica network. After chemical extraction of the chiral template, the enantioselectivity feature of the silica nanotubes was confirmed by selective adsorption of the enantiomers using circular dichroism (CD) and isothermal titration calorimetry (ITC) measurements. Although these measurements show a relatively low chiral selectivity of the silica nanotubes (ca. 6% enantiomeric excess), the system described here offers new approaches for the application of chiral porous materials in chirality. PMID:27533529

  10. Wormholes from Chiral Fields

    International Nuclear Information System (INIS)

    In this paper, Lorentzian wormholes with a phantom field and chiral matter fields have been obtained. In addition, it is shown that for different values of the gravitational coupling of the chiral fields, the wormhole geometry changes. Finally, the stability of the corresponding wormholes is studied and it is shown that are unstable (eg. Ellis's wormhole instability)

  11. Spectral signatures of chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

    We present a new way of measuring chirality, via the spectral shift of photonic band gaps in one-dimensional structures. We derive an explicit mapping of the problem of oblique incidence of circularly polarized light on a chiral one-dimensional photonic crystal with negligible index contrast to t...

  12. Long Range Chiral Imprinting of Cu(110) by Tartaric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, T J; Pushkarev, V; Wei, D; Lucci, F R; Sholl, D S; Gellman, A J; Sykes, E C. H.

    2013-10-31

    Restructuring of metals by chiral molecules represents an important route to inducing and controlling enantioselective surface chemistry. Tartaric acid adsorption on Cu(110) has served as a useful system for understanding many aspects of chiral molecule adsorption and ordering on a metal surface, and a number of chiral and achiral unit cells have been reported. Herein, we show that given the appropriate annealing treatment, singly deprotonated tartaric acid monolayers can restructure the Cu metal itself, and that the resulting structure is both highly ordered and chiral. Molecular resolution scanning tunneling microscopy reveals that singly deprotonated tartaric acid extracts Cu atoms from the Cu(110) surface layer and incorporates them into highly ordered, chiral adatom arrays capped by a continuous molecular layer. Further evidence for surface restructuring comes from images of atom-deep trenches formed in the Cu(110) surface during the process. These trenches also run in low symmetry directions and are themselves chiral. Simulated scanning tunneling microscopy images are consistent with the appearance of the added atom rows and etched trenches. The chiral imprinting results in a long-range, highly ordered unit cell covering the whole surface as confirmed by low energy electron diffraction. Details of the restructuring mechanism were further investigated via time-lapse imaging at elevated temperature. This work reveals the stages of nanoscale surface restructuring and offers an interesting method for chiral modification of an achiral metal surface.

  13. Chiral Magnetic "Superfluidity"

    CERN Document Server

    Sadofyev, Andrey V

    2015-01-01

    We study a heavy impurity moving longitudinal with the direction of an external magnetic field in an anomalous chiral medium. Such system would carry a non-dissipative current of chiral magnetic effect associated with the anomaly. We show, by generalizing Landau's criterion for superfluidity, that the "anomalous component" which gives rise to the anomalous transport will {\\it not} contribute to the drag experienced by an impurity. We argue on very general basis that those systems with a strong magnetic field would exhibit the behavior of 'superfluidity" -- the motion of the heavy impurity is frictionless, in analog to the case of a superfluid. However, this "superfluidity" exists even for chiral media at finite temperature and only in the directional longitudinal with the magnetic field, in contrast to the ordinary superfluid. We will call this novel phenomenon as the Chiral Magnetic "Superfluidity". We demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion ...

  14. Chiral pesticides: Identification, description, and environmental implications

    Science.gov (United States)

    Ulrich, Elin M.; Morrison, Candice N.; Goldsmith, Michael R.; Foreman, William T.

    2012-01-01

    Anthropogenic chemicals, including pesticides, are a major source of contamination and pollution in the environment. Pesticides have many positive uses: increased food production, decreased damage to crops and structures, reduced disease vector populations, and more. Nevertheless, pesticide exposure can pose risks to humans and the environment, so various mitigation strategies are exercised to make them safer, minimize their use, and reduce their unintended environment effects. One strategy that may help achieve these goals relies on the unique properties of chirality or molecular asymmetry. Some common terms related to chirality are defined in Table 1.

  15. 现代有机分析在中药检测食物分析和手性识别的应用%Application of Modern Organic Analysis in Traditional Chinese Medicine Test, Food Analysis and Chiral Molecular Recognition

    Institute of Scientific and Technical Information of China (English)

    张来新; 赵卫星

    2011-01-01

    Conception, application and prospect of organic analytical chemistry were briefly introduced. Application of new modern organic analysis technologies in traditional Chinese medicine test, food analysis and chiral molecular recognition was mainly discussed. At last, future development of the organic analysis was prospected.%简要介绍了有机分析化学的概念、应用与发展前景,重点综述了利用现代有机分析的新技术新方法测定中药材中药用成分研究;现代有机分析新方法新技术对食物中有关成分测定;现代有机分析在手性识别方面的应用.并对有机分析的发展进行了展望.

  16. Molecular Modeling on the Recognition of Wobble DNA Including G:T Mismatched Pairs by Two Structures of Chiral Metal Complex △,∧-[Ru(phen)2hpip]2+

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cui-Ping; WU Yan-Bo; YANG Pin

    2006-01-01

    In this work, the recognition of DNA including G:T mismatched pairs by the two different structures of[Ru(phen)2hpip]2+ was firstly studied with molecular modeling respectively. The results revealed that all of the four chiral isomers of the two structures could recognize the mismatched DNA from the minor groove orientation especially and the interaction was enantioselective and sitespecific. The two left isomers were more preferential than the right ones. Especially, the structure Ⅱ which had much lower energy after interacting with DNA was the advantaged structure. Detailed energy analysis indicated that the steric interaction in the process of the complex inserting base stack determined the recognition results and the electrostatic interaction made an effect to some extent.

  17. Chiral Magnetic Effect and Chiral Phase Transition

    Institute of Scientific and Technical Information of China (English)

    FU Wei-Jie; LIU Yu-Xin; WU Yue-Liang

    2011-01-01

    We study the influence of the chiral phase transition on the chiral magnetic effect.The azimuthal chargeparticle correlations as functions of the temperature are calculated.It is found that there is a pronounced cusp in the correlations as the temperature reaches its critical value for the QCD phase transition.It is predicted that there will be a drastic suppression of the charge-particle correlations as the collision energy in RHIC decreases to below a critical value.We show then the azimuthal charge-particle correlations can be the signal to identify the occurrence of the QCD phase transitions in RHIC energy scan experiments.

  18. Chiral dynamics and peripheral transverse densities

    Energy Technology Data Exchange (ETDEWEB)

    Granados, Carlos G. [Uppsala University (Sweden); Weiss, Christian [JLAB, Newport News, VA (United States)

    2014-01-01

    In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as the peripheral densities at transverse distances b = O(M{sub {pi}}{sup -1}) and compute them in a parametrically controlled manner. A dispersion relation connects the large-distance behavior of the transverse charge and magnetization densities to the spectral functions of the Dirac and Pauli form factors near the two--pion threshold at timelike t = 4 M{ sub {pi}}{sup 2}, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior (Yukawa tail) of the isovector transverse densities in the "chiral" region b = O(M{sub {pi}}{sup -1}) and the "molecular" region b = O(M{sub N}{sup 2}/M{sub {pi}}{sup 3}); (b) perform the heavy-baryon expansion of the transverse densities; (c) explain the relative magnitude of the peripheral charge and magnetization densities in a simple mechanical picture; (d) include Delta isobar intermediate states and study the peripheral transverse densities in the large-N{ sub c} limit of QCD; (e) quantify the region of transverse distances where the chiral components of the densities are numerically dominant; (f) calculate the chiral divergences of the b{sup 2}-weighted moments of the isovector transverse densities (charge and anomalous magnetic radii) in the limit M{sub {pi}} -> 0 and determine their spatial support. Our approach provides a concise formulation of the spatial structure of the nucleon's chiral component and offers new insights into basic properties of the chiral expansion. It relates the information extracted from low-t elastic form factors to the generalized parton distributions probed in peripheral high-energy scattering processes.

  19. Applications of chiral symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, R.D.

    1995-03-01

    The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T{sub {chi}} implies that the {rho} and a{sub 1} vector mesons are degenerate in mass. In a gauged linear sigma model the {rho} mass increases with temperature, m{sub {rho}}(T{sub {chi}}) > m{sub {rho}}(0). The author conjectures that at T{sub {chi}} the thermal {rho} - a{sub 1}, peak is relatively high, at about {approximately}1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The {omega} meson also increases in mass, nearly degenerate with the {rho}, but its width grows dramatically with temperature, increasing to at least {approximately}100 MeV by T{sub {chi}}. The author also stresses how utterly remarkable the principle of vector meson dominance is, when viewed from the modern perspective of the renormalization group. Secondly, he discusses the possible appearance of disoriented chiral condensates from {open_quotes}quenched{close_quotes} heavy ion collisions. It appears difficult to obtain large domains of disoriented chiral condensates in the standard two flavor model. This leads to the last topic, which is the phase diagram for QCD with three flavors, and its proximity to the chiral critical point. QCD may be very near this chiral critical point, and one might thereby generated large domains of disoriented chiral condensates.

  20. Structural and magnetic properties of ferrimagnetic ε-phase Mn4N and antiferromagnetic ζ-phase Mn10N thin films on MgO(001)

    Science.gov (United States)

    Foley, Andrew; Corbett, Joseph; Richard, Andrea L.; Alam, Khan; Ingram, David C.; Smith, Arthur R.

    2016-07-01

    Single phase ε-Mn4N and ζ-Mn10N thin films are grown on MgO(001) using molecular beam epitaxy. The films are identified and characterized using reflection high-energy electron diffraction, x-ray diffraction, back scattered electron scanning electron microscopy, atomic/magnetic force microscopy and Rutherford backscattering spectrometry. These films are found to be highly smooth with root-mean-squared roughnesses 3.39 nm and below. The quality of ε-Mn4N grown is strongly dependent on substrate temperature during growth. Epitaxial growth of substantial grains composed of the antiferromagnetic η-phase Mn3N2 side by side with ferrimagnetic ε-phase grains is observed when growth temperature is below 480 °C. Ising domains isolated within areas roughly 0.5 μm across are observed in the ferrimagnetic ε-phase grains of samples consisting of a mix of η- and ε-phase grains. Magnetic domains following semi-continuous paths, which are 0.7-7.2 μm across, are observed in single phase ε-Mn4N. Measurements of the ζ-phase detail the structure and magnetism of the material as high Mn content γ-type ζ-phase with a regular surface corrugation along the [100]-direction and antiferromagnetic.

  1. The covariant chiral ring

    Science.gov (United States)

    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.

  2. The Covariant Chiral Ring

    CERN Document Server

    Bourget, Antoine

    2015-01-01

    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 T4, 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.

  3. Catalysis of Dynamical Chiral Symmetry Breaking by Chiral Chemical Potential

    CERN Document Server

    Braguta, V V

    2016-01-01

    In this paper we study the properties of media with chiral imbalance parameterized 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 a 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.

  4. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    Science.gov (United States)

    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.

  5. Color chiral solitons

    CERN Document Server

    Novozhilov, V Yu; Novozhilov, Victor; Novozhilov, Yuri

    2002-01-01

    We discuss specific features of color chiral solitons (asymptotics, possibility of confainment, quantization) at example of isolated SU(2) color skyrmions, i.e. skyrmions in a background field which is the vacuum field forming the gluon condensate.

  6. Chiral Odd GPDs

    Directory of Open Access Journals (Sweden)

    Goldstein Gary R.

    2015-01-01

    Full Text Available Nucleon spin structure, transversity and the tensor charge are of central importance to understanding the role of QCD in hadronic physics. A new approach to measuring orbital angular momenta of quarks in the proton via twist 3 GPDs is shown. The “flexible parametrization” of chiral even GPDs is reviewed and its transformation into the chiral odd sector is discussed. The resulting parametrization is applied to recent data on π0 and η electroproduction.

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

    Science.gov (United States)

    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

  8. Epitaxial Growth of Hard Ferrimagnetic Mn3Ge Film on Rhodium Buffer Layer

    Directory of Open Access Journals (Sweden)

    Atsushi Sugihara

    2015-06-01

    Full Text Available Mn\\(_3\\Ge has a tetragonal Heusler-like D0\\(_{22}\\ crystal structure, exhibiting a large uniaxial magnetic anisotropy and small saturation magnetization due to its ferrimagnetic spin structure; thus, it is a hard ferrimagnet. In this report, epitaxial growth of a Mn\\(_3\\Ge film on a Rh buffer layer was investigated for comparison with that of a film on a Cr buffer layer in terms of the lattice mismatch between Mn\\(_3\\Ge and the buffer layer. The film grown on Rh had much better crystalline quality than that grown on Cr, which can be attributed to the small lattice mismatch. Epitaxial films of Mn\\(_3\\Ge on Rh show somewhat small coercivity (\\(H_{\\rm c}\\ = 12.6 kOe and a large perpendicular magnetic anisotropy (\\(K_{\\rm u}\\ = 11.6 Merg/cm\\(^3\\, comparable to that of the film grown on Cr.

  9. Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet

    Science.gov (United States)

    Mizukami, S.; Sugihara, A.; Iihama, S.; Sasaki, Y.; Suzuki, K. Z.; Miyazaki, T.

    2016-01-01

    Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn3Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant is approximately 60 Mrad/s and is comparable with those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.

  10. Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet

    Energy Technology Data Exchange (ETDEWEB)

    Mizukami, S., E-mail: mizukami@wpi-aimr.tohoku.ac.jp; Sugihara, A.; Suzuki, K. Z.; Miyazaki, T. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Iihama, S.; Sasaki, Y. [Department of Applied Physics, Tohoku University, Sendai 980-8579 (Japan)

    2016-01-04

    Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn{sub 3}Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant is approximately 60 Mrad/s and is comparable with those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.

  11. Interlayer Coupling in Co/Ti/(Gd-Co)/Ti Artificial Layered Ferrimagnet

    Institute of Scientific and Technical Information of China (English)

    A.V.Svalov; A.Fernández; V.O.Vas'kovskiy; M.Tejedor; R.Lopez Anton; J.M.Barandiarán; G.V.Kurlyandskaya

    2005-01-01

    @@ The magnetic properties and the structure of [Co/Ti/Gd0.36Co0.64/Ti]4/Co multilayers are investigated by means of torque magnetometer, vibrating sample magnetometer and transverse magneto-optic Kerr effect (TMOKE)measurements and the atomic force microscopy. Due to interlayer exchange interaction, Co and Gd-Co layers form a macroscopic ferrimagnetic system. The change in the sign of the TMOKE hysteresis loops near the compensation temperature and field induced magnetic phase transitions are found. The latter can be characterized by a critical field which shows a linear variation with the temperature. The magnetic properties of these multilayers from many points of view are similar to those of bulk ferrimagnets.

  12. Schwinger-boson approach to anisotropy ferrimagnetic chain with bond alternation

    Institute of Scientific and Technical Information of China (English)

    李殷翔; 陈斌

    2015-01-01

    We use the Schwinger-boson approach to study the anisotropy ferrimagnetic spin-(1/2,1) chain with bond alternation. Based on the effect of bond alternationδ, we obtain energy gap, free energy, and specific heat, respectively. The specific heat with larger bond alternation (δ >0.7) displays a peak at low temperature. Based on the effect of X X Z anisotropy parameter∆, we present excited spectrums, free energy, and specific heat, respectively.

  13. Chirality as a physical aspect of structure formation in biological macromolecular systems

    Science.gov (United States)

    Malyshko, E. V.; Tverdislov, V. A.

    2016-08-01

    A novel regularity of hierarchical structures is found in the formation of chiral biological macromolecular systems. The formation of structures with alternating chirality (helical structures) serves as an instrument of stratification. The ability of a carbon atom to form chiral compounds is an important factor that determined the carbon basis of living systems on the Earth as well as their development through a series of chiral bifurcations. In the course of biological evolution, the helical structures became basic elements of the molecular machines in the cell. The discreteness of structural levels allowed the mechanical degrees of freedom formation in the molecular machines in the cell.

  14. Ferrimagnetic Minerals in Red Palesols of pleistocene Epoch,Eastern China

    Institute of Scientific and Technical Information of China (English)

    卢升高

    2000-01-01

    The type,grain size and origin of ferimagnetic minerals separated from red paleosols of pleistocene Epoch(Q2)in eastern China ,were studied by using mineral magnetic measurement,X-ray powder diffraction and electron microscopy.Results showed that the iron oxider in red paleosols were composed of hematite(α-Fe2O3),maghemite(γ-Fe2O3) and goethite(α-FeOOH),Mineral magnetic parameters and X-ray diffraction patterns indicated that maghemite was the dominant remanence carrier in red paleosols,which is characterized by superparamagnetic(SP) and stable single domain(SSD) grains,The variations of magnetic susceptibility(χ) ,anhysteretic magnetic susceptibility(χRAM)and saturation isothermal remanent magnetization(SIRM) for red paleosols following heating to various temperatures showed two peak values at 700℃ and 900℃.The spherulitic magnetic particles measuring 250-1000μm in diameter in red paleosols were separated by the magnetic separation method,indicating that these magnetic particles were an assemblage of superparamagnetic and stable single domain ferrimagnetic grains,It is suggested that the ferrimagnetic minerals of red paleosols be a pedogenic ferrimagnetic component under high temperature and high humid conditions in the Pleistocene Fpoch(Q2).It is concluded that the magnetism characteristics of red paleosols can be used to evaluate the environmental changes of Quaternary in eastern China.

  15. Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA

    Directory of Open Access Journals (Sweden)

    Fumitoshi Yagishita

    2013-11-01

    Full Text Available Dynamic atroposelective resolution of chiral salts derived from oily racemic nicotinamides and enantiopure dibenzoyltartaric acid (DBTA was achieved by crystallization. The absolute structures of the axial chiral nicotinamides were determined by X-ray structural analysis. The chirality could be controlled by the selection of enantiopure DBTA as a chiral auxiliary. The axial chirality generated by dynamic salt formation was retained for a long period after dissolving the chiral salt in solution even after removal of the chiral acid. The rate of racemization of nicotinamides could be controlled based on the temperature and solvent properties, and that of the salts was prolonged compared to free nicotinamides, as the molecular structure of the pyridinium ion in the salts was different from that of acid-free nicotinamides.

  16. Synthesis of Stable and Soluble One-Handed Helical Homopoly(substituted acetylenes without the Coexistence of Any Other Chiral Moieties via Two-Step Polymer Reactions in Membrane State: Molecular Design of the Starting Monomer

    Directory of Open Access Journals (Sweden)

    Takashi Kaneko

    2012-01-01

    Full Text Available A soluble and stable one-handed helical poly(substituted phenylacetylene without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1 removing the chiral groups (desubstitution; and (2 introduction of achiral long alkyl groups at the same position as the desubstitution to enhance the solubility of the resulting one-handed helical polymer (resubstitution. The starting chiral monomer should have four characteristic substituents: (i a chiral group bonded to an easily hydrolyzed spacer group; (ii two hydroxyl groups; (iii a long rigid hydrophobic spacer between the chiral group and the polymerizing group; (iv a long achiral group near the chiral group. As spacer group a carbonate ester was selected. The two hydroxyl groups formed intramolecular hydrogen bonds stabilizing a one-handed helical structure in solution before and after the two-step polymer reactions in membrane state. The rigid long hydrophobic spacer, a phenylethynylphenyl group, enhanced the solubility of the starting polymer, and realized effective chiral induction from the chiral side groups to the main chain in the asymmetric-induced polymerization. The long alkyl group near the chiral group avoided shrinkage of the membrane and kept the reactivity of resubstitution in membrane state after removing the chiral groups. The g value (g = ([θ]/3,300/ε for the CD signal assigned to the main chain in the obtained final polymer was almost the same as that of the starting polymer in spite of the absence of any other chiral moieties. Moreover, since the one-handed helical structure was maintained by the intramolecular hydrogen bonds in a solution, direct observation of the one-handed helicity of the final homopolymer has been realized in CD for the solution for the first time.

  17. Dynamic Chirality in Nuclei

    International Nuclear Information System (INIS)

    Chirality has recently been proposed as a novel feature of rotating nuclei [1]. Because the chiral symmetry is dichotomic, its spontaneous breaking by the axial angular momentum vector leads to doublets of closely lying rotational bands of the same parity. To investigate nuclear chirality, next to establish the existence of almost degenerate rotational bands, it is necessary to measure also other observables and compare them to the model predictions. The crucial test for the suggested nuclei as candidates to express chirality is based on precise lifetime measurements. Two lifetime experiments and theoretical approaches for the description of the experimental results will be presented. Lifetimes of exited states in 134Pr were measured [2,3] by means of the recoil distance Doppler-shift and Doppler-shift attenuation techniques. The branching ratios and the electric or magnetic character of the transitions were also investigated [3]. The experiments were performed at IReS, Strasbourg, using the EUROBALL IV spectrometer, in conjunction with the inner bismuth germanate ball and the Cologne coincidence plunger apparatus. Exited states in 134Pr were populated in the fusion-evaporation reaction 119Sn(19F, 4n)134Pr. The possible chiral interpretation of twin bands was investigated in the two-quasiparticle triaxial rotor [1] and interacting boson-fermion-fermion models [4]. Both theoretical approaches can describe the level-scheme of 134Pr. The analysis of the wave functions has shown that the possibility for the angular momenta of the proton, neutron, and core to find themselves in the favorable, almost orthogonal geometry, is present but is far from being dominant [3,5]. The structure is characterized by large β and γ fluctuations. The existence of doublets of bands in 134Pr can be attributed to weak chirality dominated by shape fluctuations. In a second experiment branching ratios and lifetimes in 136Pm were measured by means of the recoil distance Doppler-shift and

  18. Molecular recognition on supramolecular systems (XXXV)——Synthesis of novel β-cyclodextrin derivative bearing pyridinio group and its chiral discrimination of amino acids

    Institute of Scientific and Technical Information of China (English)

    刘育; 康诗钊

    2001-01-01

    A novel p-cyclodextrin derivative 4 bearing a pyridinio group on the primary side was synthesized by the reaction of 2-aminopyridine with 6-p-cyclodextrin monoaldehyde 3, and its complexation stability constants with several aliphatic amino acids have been determined in phosphate buffer solution ( pH = 7.2, 0.1 mol ?L-1) at 25℃by using spectrofluorometric titrations. The stoichiometry is 1 : 1 for the inclusion complexation of amino acids with compound 4. Circular dichroism study indicates that the aromatic moiety was embedded shallowly into the cyclodextrin cavity. As a spectral probe, the pyridinio group in the modified cyclodextrin can recognize not only differences of the size and shape of amino acid molecules, but also the L/D-amino acid chiral iso-mer. As compared with mono-[6-(1-pyridinio)-6-deoxy]-p-cyclodextrin 5, compound 4 switched the enantiomer preference for L- to D-isomer, and showed the highest enantioselectivity of 5.4 for D/L-serine. These results are discussed from the viewpoints of ge

  19. Molecular recognition on supramolecular systems (XXXV)-- Synthesis of novel b-cyclodextrin derivative bearing pyridinio group and its chiral discrimination of amino acids

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel b-cyclodextrin derivative 4 bearing a pyridinio group on the primary side was synthesized by the reaction of 2-aminopyridine with 6-b-cyclodextrin monoaldehyde 3, and its complexation stability constants with several aliphatic amino acids have been determined in phosphate buffer solution ( pH = 7.2, 0.1 mol·L-1) at 25 ℃ by using spectrofluormetric titrations. The stoichiometry is 1︰1 for the inclusion complexation of amino acids with compound 4. Circular dichroism study indicates that the aromatic moiety was embedded shallowly into the cyclodextrin cavity. As a spectral probe, the pyridinio group in the modified cyclodextrin can recognize not only differences of the size and shape of amino acid molecules, but also the L/D-amino acid chiral isomer. As com-pared with mono-[6-(1-pyridinio)-6-deoxy]-b-cyclodextrin 5, compound 4 switched the enantiomer preference for L- to D-isomer, and showed the highest enantioselectivity of 5.4 for D/L-serine. The-se results are discussed from the viewpoints of geometric compensation, induced-fit concept and cooperation of several weak interactions.

  20. Chiral anomalies and differential geometry

    Energy Technology Data Exchange (ETDEWEB)

    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)

  1. Anomalous Hall effect in epitaxial ferrimagnetic anti-perovskite Mn{sub 4−x}Dy{sub x}N films

    Energy Technology Data Exchange (ETDEWEB)

    Meng, M.; Wu, S. X., E-mail: wushx3@mail.sysu.edu.cn; Zhou, W. Q.; Ren, L. Z.; Wang, Y. J.; Wang, G. L.; Li, S. W., E-mail: stslsw@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2015-08-07

    Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn{sub 4−x}Dy{sub x}N films grown by molecular-beam epitaxy. The introduction of Dy changes the AHE dramatically, even changes its sign, while the variations in magnetization are negligible. Two sign reversals of the AHE (negative-positive-negative) are ascribed to the variation of charge carriers as a result of Fermi surface reconstruction. We further demonstrate that the AHE current J{sub AH} is dissipationless (independent of the scattering rate), by confirming that anomalous Hall conductivity, σ{sub AH}, is proportional to the carrier density n at 5 K. Our study may provide a route to further utilize antiperovskite manganese nitrides in spintronics.

  2. Compensation temperatures of mixed ferro-ferrimagnetic ternary alloys

    International Nuclear Information System (INIS)

    We present a Monte Carlo study of a mixed Ising model of the type ABPC1-P, in a square lattice, were spins SA=+/-3/2,+/-1/2 of one sublattice are in alternating sites with spins SB=+/-52,+/-32,+/-12 or spins SC=+/-1,0, located on the other sublattice with concentrations P and 1-P, respectively. The SA interact ferromagnetically with the SB and antiferromagnetically with the SC. The results indicate that this simple model can reproduce several aspects of the behavior of a class of molecular compounds called Prussian blue analogs such as a critical temperature that it is independent on the concentration of different types of spins, and the appearance of compensation temperatures in a certain range of values of the concentration of the different species

  3. Chiral Electroweak Currents in Nuclei

    CERN Document Server

    Riska, D O

    2016-01-01

    The development of the chiral dynamics based description of nuclear electroweak currents is reviewed. Gerald E. (Gerry) Brown's role in basing theoretical nuclear physics on chiral Lagrangians is emphasized. Illustrative examples of the successful description of electroweak observables of light nuclei obtained from chiral effective field theory are presented.

  4. Chiral Synthons in Pesticide Syntheses

    NARCIS (Netherlands)

    Feringa, Bernard

    1988-01-01

    The use of chiral synthons in the preparation of enantiomerically pure pesticides is described in this chapter. Several routes to chiral synthons based on asymmetric synthesis or on natural products are illustrated. Important sources of chiral building blocks are reviewed. Furthermore the implicatio

  5. Chiral Sensitivity in the Dissociative Electron Attachment of Halocamphor Molecules

    Science.gov (United States)

    Dreiling, Joan

    2016-05-01

    We have demonstrated chirally-dependent molecular destruction when incident longitudinally-spin-polarized (chiral) electrons break bonds in chiral molecules. This chiral sensitivity was observed through an asymmetry in the dissociative electron attachment (DEA) reaction rate with chiral 3-bromocamphor (C10 H15 BrO). Such an observation provides an unambiguous demonstration of the idea underlying the Vester-Ulbricht hypothesis, which attempts to explain the origins of the homochirality that is observed in many biological systems. While the lack of inversion symmetry in these reactions allows the effects we observe to occur, their dynamic causes are poorly understood. We have further studied the asymmetries in the DEA rates for two additional halocamphor molecules, 3-iodocamphor (C10 H15 IO) and 10-iodocamphor, in a systematic effort to illuminate the mechanisms responsible for the chiral sensitivity. The DEA signal depends on the sign of the incident electron helicity for a given target handedness in all molecules, and it varies with both the atomic number and the location of the heaviest atom in the molecule. Surprisingly, the DEA asymmetries for 10-iodocamphor, in which the heaviest atom is farther from a chiral center than for the other molecules, produced the largest asymmetries. This work was performed at the University of Nebraska-Lincoln. This project was funded by NSF Grant PHY-1206067.

  6. Sum-Frequency Generation from Chiral Media and Interfaces

    International Nuclear Information System (INIS)

    Sum frequency generation (SFG), a second-order nonlinear optical process, is electric-dipole forbidden in systems with inversion symmetry. As a result, it has been used to study chiral media and interfaces, systems intrinsically lacking inversion symmetry. This thesis describes recent progresses in the applications of and new insights into SFG from chiral media and interfaces. SFG from solutions of chiral amino acids is investigated, and a theoretical model explaining the origin and the strength of the chiral signal in electronic-resonance SFG spectroscopy is discussed. An interference scheme that allows us to distinguish enantiomers by measuring both the magnitude and the phase of the chiral SFG response is described, as well as a chiral SFG microscope producing chirality-sensitive images with sub-micron resolution. Exploiting atomic and molecular parity nonconservation, the SFG process is also used to solve the Ozma problems. Sum frequency vibrational spectroscopy is used to obtain the adsorption behavior of leucine molecules at air-water interfaces. With poly(tetrafluoroethylene) as a model system, we extend the application of this surface-sensitive vibrational spectroscopy to fluorine-containing polymers

  7. Sum-Frequency Generation from Chiral Media and Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Na

    2006-02-13

    Sum frequency generation (SFG), a second-order nonlinear optical process, is electric-dipole forbidden in systems with inversion symmetry. As a result, it has been used to study chiral media and interfaces, systems intrinsically lacking inversion symmetry. This thesis describes recent progresses in the applications of and new insights into SFG from chiral media and interfaces. SFG from solutions of chiral amino acids is investigated, and a theoretical model explaining the origin and the strength of the chiral signal in electronic-resonance SFG spectroscopy is discussed. An interference scheme that allows us to distinguish enantiomers by measuring both the magnitude and the phase of the chiral SFG response is described, as well as a chiral SFG microscope producing chirality-sensitive images with sub-micron resolution. Exploiting atomic and molecular parity nonconservation, the SFG process is also used to solve the Ozma problems. Sum frequency vibrational spectroscopy is used to obtain the adsorption behavior of leucine molecules at air-water interfaces. With poly(tetrafluoroethylene) as a model system, we extend the application of this surface-sensitive vibrational spectroscopy to fluorine-containing polymers.

  8. Chiral Quantum Optics

    CERN Document Server

    Lodahl, Peter; Stobbe, Søren; Schneeweiss, Philipp; Volz, Jürgen; Rauschenbeutel, Arno; Pichler, Hannes; Zoller, Peter

    2016-01-01

    At the most fundamental level, the interaction between light and matter is manifested by the emission and absorption of single photons by single quantum emitters. Controlling light--matter interaction is the basis for diverse applications ranging from light technology to quantum--information processing. Many of these applications are nowadays based on photonic nanostructures strongly benefitting from their scalability and integrability. The confinement of light in such nanostructures imposes an inherent link between the local polarization and propagation direction of light. This leads to {\\em chiral light--matter interaction}, i.e., the emission and absorption of photons depend on the propagation direction and local polarization of light as well as the polarization of the emitter transition. The burgeoning research field of {\\em chiral quantum optics} offers fundamentally new functionalities and applications both for single emitters and ensembles thereof. For instance, a chiral light--matter interface enables...

  9. Holographic Chiral Magnetic Spiral

    International Nuclear Information System (INIS)

    We study the ground state of baryonic/axial matter at zero temperature chiral-symmetry broken phase under a large magnetic field, in the framework of holographic QCD by Sakai-Sugimoto. Our study is motivated by a recent proposal of chiral magnetic spiral phase that has been argued to be favored against previously studied phase of homogeneous distribution of axial/baryonic currents in terms of meson super-currents dictated by triangle anomalies in QCD. Our results provide an existence proof of chiral magnetic spiral in strong coupling regime via holography, at least for large axial chemical potentials, whereas we don't find the phenomenon in the case of purely baryonic chemical potential. (author)

  10. Chiral quark model

    Indian Academy of Sciences (India)

    H Weigel

    2003-11-01

    In this talk I review studies of hadron properties in bosonized chiral quark models for the quark flavor dynamics. Mesons are constructed from Bethe–Salpeter equations and baryons emerge as chiral solitons. Such models require regularization and I show that the two-fold Pauli–Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions.

  11. Chiral Heat Wave and wave mixing in chiral media

    CERN Document Server

    Chernodub, M N

    2016-01-01

    We show that a hot rotating fluid of relativistic chiral fermions possesses a new gapless collective excitation associated with coherent propagation of energy density and chiral density waves along the axis of rotation. This excitation, which we call the Chiral Heat Wave, emerges due to a mixed gauge-gravitational anomaly. At finite density the Chiral Heat Wave couples to the Chiral Vortical Wave while in the presence of an external magnetic field it mixes with the Chiral Magnetic Wave. We find that the coupled waves - which are coherent fluctuations of the vector, axial and energy currents - have generally different velocities compared to the velocities of the individual waves. We also demonstrate that rotating chiral systems subjected to external magnetic field possess non-propagating metastable thermal excitations, the Dense Hot Spots.

  12. Binary mixtures of chiral gases

    CERN Document Server

    Presilla, Carlo

    2015-01-01

    A possible solution of the well known paradox of chiral molecules is based on the idea of spontaneous symmetry breaking. At low pressure the molecules are delocalized between the two minima of a given molecular potential while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a phase transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. In particular, at pressure greater than a critical value no inversion line is observed. These data are well accounted for by a model previously developed and recently extended to mixtures. In the present paper, we discuss the variation of the critical pressure in binary mixtures as a function of the fractions of the constituents.

  13. Vibrational evidence for chiral recognition phenomena in vacuo

    Science.gov (United States)

    Suhm, Martin A.

    2007-06-01

    Molecules and molecular conformations which cannot be superimposed on their mirror image are chiral. Chirality or handedness plays an important role throughout the life sciences. When two molecules interact, they can sense their relative handedness, giving rise to spectroscopic signatures of chiral recognition. This is often mediated by hydrogen bonds, most versatile and directional intermolecular interactions. If the distinction between the homo- and heteroconfigurational pairs of molecules is large enough, chiral discrimination, i.e. differences in abundance may occur. The contact between two flexible, transiently chiral molecules may induce a matching of their handedness, i.e. chirality synchronization. Such phenomena are best studied at low temperatures in vacuum isolation, without perturbing interactions [1]. Structural information on the isolated molecular complexes can be obtained by rotational spectroscopy [2], if there is a sufficient dipole moment. Vibrational spectroscopy [3] provides a more universal, but also more coarse-grained access to these phenomena. Our group has reported the first spectroscopic example of chiral recognition between constitutionally identical molecules in the gas phase [4]. We have found a case of chiral discrimination in tetrameric aggregates of methyl lactate, where the relative configuration controls the hydrogen bond topology [5]. In the case of alcohols, we have observed different degrees of chirality synchronization up to a quantitative chirality matching in dimers of trifluoroethanol [6]. These discoveries became possible through the use of a powerful combination of FTIR spectroscopy and high-throughput, pulsed supersonic nozzle expansions into large vacuum chambers [7]. The isolated and elementary character of the investigated molecular assemblies is favourable for quantum chemical treatments [8]. Valuable benchmarks for the modeling of more complex chiral recognition phenomena are thus established. [1] A. Al-Rabaa, E. Br

  14. Synthesis and Catalytic Asymmetric Reaction of Chiral Pyridine Prolinol Derivatives

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao; ZHANG Yong-Xin; DU Da-Ming; HUA Wen-Ting

    2003-01-01

    @@ The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction.

  15. Interweaving Chiral Spirals

    CERN Document Server

    Kojo, Toru; Fukushima, Kenji; McLerran, Larry; Pisarski, Robert D

    2011-01-01

    We elaborate how to construct the interweaving chiral spirals in (2+1) dimensions, that is defined as a superposition of differently oriented chiral spirals. We divide the two-dimensional Fermi sea into distinct wedges characterized by the opening angle 2 Theta and the depth Q \\simeq pF, where pF is the Fermi momentum. Each wedge earns an energy gain by forming a single chiral spiral. The optimal values for Theta and Q are chosen by the balance between this energy gain and the energy costs from the deformed Fermi surface (dominant at large Theta) and patch-patch interactions (dominant at small Theta). We estimate these energy gains and costs by means of the expansions in terms of 1/Nc, Lambda_QCD/Q, and Theta using a non-local four-Fermi interaction model: At small 1/Nc the mass gap (chiral condensate) is large enough and the interaction among quarks and the condensate is local in momentum space thanks to the form factor in our non-local model. The fact that patch-patch interactions lie only near the patch bo...

  16. S-布洛芬分子印迹膜的制备与手性拆分性能%Preparation and Chiral Resolution Performance of S-Ibuprofen Molecularly Imprinted Membranes

    Institute of Scientific and Technical Information of China (English)

    刘丽娟; 许振良; 张颖

    2012-01-01

    S-ibuprofen molecularly imprinted membrane was prepared using PVDF hollow fiber membrane as the support. The selective binding properties and chiral resolution performance of the membranes were investigated. The results show that the S-ibuprofen molecularly imprinted membrane has the high binding capacity for S-ibuprofen, the binding amount for S-ibuprofen is up to 22.8 μmol/g. Permeation experiments of S-ibuprofen and R-ibuprofen across the membrane imprinted with S-ibuprofen show that the membrane is enantioselective, diffusion of the template enantiomer faster than that of its optical antipode. The separation factor is up to 1.17. The permeation mechanism coincides with "facilitated transport" or "facilitated diffusion" model. The SEM results also indicate that a thin imprinted membrane is coated on the surface of the PVDF hollow fiber membrane.%采用聚偏氟乙烯(PVDF)中空纤维膜为支撑体,制备了S布洛芬分子印迹膜,并对膜的选择结合性及手性拆分性能进行了研究。研究结果表明,S布洛芬分子印迹复合膜对S布洛芬具有较好的选择结合性,在膜上的结合量达到22.8μmol/g。膜的错流过滤实验表明,S-布洛芬透过膜的速率大于R-布洛芬,分离因子为1.17,这将有利于外消旋布洛芬的分离。扫描电镜(SME)也同样表明,在膜的表面涂上了一薄层印记膜。

  17. Influence of high energetic irradiations with heavy ions on the magnetic properties of ferrimagnetic iron granates

    International Nuclear Information System (INIS)

    With the aim of magnetic, magnetooptical and optical measurement techniques ion tracks produced by energetic heavy ion irradiations in ferrimagnetic granates have been investigated. In detail, the irradiations done in the temperature range 4.2 K <= T <= 550 K affect the saturation magnetization, the uniaxial anisotropy field, the Faraday rotation, the optical absorption and the value of the Curie-temperature. An interpretation of the observed radiation effects has been tried on the basis of the induced defect structures in the granates. (RK)

  18. Neutron-Scattering Study of Spin Waves in the Ferrimagnet RbNiF3

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.

    1972-01-01

    RbNiF3 is a transparent hexagonal ferrimagnet with Tc=133°K. Below Tc the Ni++ magnetic moments are aligned collinearly in ferromagnetic hexagonal sheets with a stacking sequence of these planes BBABBA such that the A spins are antiparallel to the B spins. This magnetic structure is determined...... by a 180° antiferromagnetic exchange between nearest-neighbor A, B spins and a 90° ferromagnetic exchange between nearest-neighbor B spins. In this paper we report a detailed inelastic-neutron-scattering study of the spin waves in RbNiF3 both at low temperatures and through Tc. The magnetic unit cell...

  19. Dielectric behaviour of hexagonal ferrimagnetic MFe12O19 (M=Ca, Sr and Ba) compounds

    International Nuclear Information System (INIS)

    Ferrimagnetic compounds CaM, SrM and BaM with hexagonal structure related to magnetoplumbite type have been synthesized by ceramic route. The phase purity and unit cell parameters have been confirmed by x-ray powder diffractometric data. The dielectric constant (is an element of) and loss tangent (tanδ) of these pure hexaferrites are measured at 300 K in the frequency range 100 Hz to 1 MHz using a impedance analyser. The plots of dielectric constant (is an element of) versus frequency show normal behaviour which is usually observed for ferrites. Frequency dependence of dielectric loss tangent (tanδ) is also investigated. (author)

  20. Chiral magnetic effect without chirality source in asymmetric Weyl semimetals

    CERN Document Server

    Kharzeev, Dmitri; Meyer, Rene

    2016-01-01

    We describe a new type of the Chiral Magnetic Effect (CME) that should occur in Weyl semimetals with an asymmetry in the dispersion relations of the left- and right-handed chiral Weyl fermions. In such materials, time-dependent pumping of electrons from a non-chiral external source generates a non-vanishing chiral chemical potential. This is due to the different capacities of the left- and right-handed (LH and RH) chiral Weyl cones arising from the difference in the density of states in the LH and RH cones. The chiral chemical potential then generates, via the chiral anomaly, a current along the direction of an applied magnetic field even in the absence of an external electric field. The source of chirality imbalance in this new setup is thus due to the band structure of the system and the presence of (non-chiral) electron source, and not due to the parallel electric and magnetic fields. We illustrate the effect by an argument based on the effective field theory, and by the chiral kinetic theory calculation f...

  1. Influence of ion bombardment induced patterning of exchange bias in pinned artificial ferrimagnets on the interlayer exchange coupling

    Energy Technology Data Exchange (ETDEWEB)

    Schmalhorst, Jan; Reiss, Guenter; Hoenik, V. [Thin Films and Nanostructures, Department of Physics, Univ. Bielefeld (Germany); Weis, Tanja; Engel, Dieter; Ehresmann, Arno [Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology, Kassel Univ. (Germany)

    2007-07-01

    Artificial ferrimagnets (AFi) have many applications as, e.g., pinned reference electrodes in magnetic tunnel junctions. It is known that the application of ion bombardment induced magnetic patterning with He ions on a single layer reference electrode of magnetic tunnel junctions is possible. For some applications a combination of ion bombardment induced magnetic patterning and artificial ferrimagnets as a reference electrode is desirable. The effect of ion bombardment induced magnetic patterning on pinned artificial ferrimagnets with a Ru interlayer which is frequently used in magnetic tunnel junctions as well as pinned AFis with a Cu interlayer has been tested. Special attention has been given to the question whether the antiferromagnetic interlayer exchange coupling can withstand the ion dose necessary to turn the exchange bias.

  2. Diluted orbital degeneracy and large orthorhombic distortions in ferrimagnetic spinel CuxMn3 -xO4

    Science.gov (United States)

    Lee, Kee Hwan; Chang, Hun; Hwang, In Yong; Chung, Jae-Ho; Kang, Hyun Wook; Kim, Su Jae; Lee, Seongsu

    2015-02-01

    We report large orthorhombic distortions in the ferrimagnetic tetragonal (c >a ) spinel CuxMn3 -xO4 stabilized by a few percent of Cu doping. The orthorhombic strains of the ferrimagnetic phases increased linearly to the doping and reached up to ɛ ≈8.2 ×10-3 for x =0.19 , which is three times larger than the saturated value under external magnetic fields. For high doping (x ≳0.17 ), the distortions first appeared in the paramagnetic phases and underwent further enhancement simultaneously with the onset of the noncollinear ferrimagnetic ordering. We present the rich magnetostructural phase diagram of CuxMn3 -xO4 , and argue that the diluted t2 orbital degeneracy of Cu2 + under tetrahedral crystal field breaks the global symmetry and triggers the orthorhombic instability inherent in Mn3O4 .

  3. Detecting the chirality for coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Cao Huijuan [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China); Hu Lian [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: huliancaohj@yahoo.com

    2008-04-21

    We propose a scheme to detect the chirality for a system consisting of three coupled quantum dots. The chirality is found to be determined by the frequency of the transition between chiral states under the chiral symmetry broken perturbation. The results are important to construct quantum gates and to demonstrate chiral entangle states in the triangle spin dots.

  4. Magnetization pole reversal of ferrimagnetic ludwigites Mn{sub 3−x}Ni{sub x}BO{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Bezmaternykh, L.N.; Kolesnikova, E.M., E-mail: ekoles@iph.krasn.ru; Eremin, E.V.; Sofronova, S.N.; Volkov, N.V.; Molokeev, M.S.

    2014-09-01

    The conditions for the flux growth of new Mn–Ni oxyborates with the ludwigite structure are reported. Magnetic measurement data for the samples with nickel and manganese predominance are presented. Magnetization pole reversal of the ferrimagnetic phases is established and analyzed in the framework of a model comprising two antiferromagnetically interacting subsystems, each being ferrimagnetically ordered. - Highlights: • Single crystals of new Mn–Ni oxyborates with ludwigite structure were synthesized. • X-ray study of synthesized single crystals was carried out. • We present magnetic measurement data for the samples with nickel and manganese predominance. • We report two different scenarios of alternative-sign behavior of magnetic susceptibility.

  5. Study of Properties of Mixed Ferro-Ferrimagnetic Ising Compounds with (AxB1-x)yC

    Institute of Scientific and Technical Information of China (English)

    XIN Zi-Hua; WEI Guo-Zhu; LIANG Ya-Qiu; ZHANG Qi

    2004-01-01

    The magnetic properties of the mixed ferro-ferrimagnetic compounds with (AxB1-x)yC, where A, B, and C are three different magnetic ions and form three different sublattices, are studied by using the standard mean-field theory. The phase diagram which is related to experimental work of molecule-based ferro-ferrimagnet (NiⅡxMn1Ⅱ-x)1.5[CrⅢ(CN)6]· zH2O is obtained. The magnetization curves, internal energy, and specific heat of the same mixed (Ax B1- x) y C system are also investigated.

  6. Study of Properties of Mixed Ferro-Ferrimagnetic Ising Compounds with (AxB1-x)yC

    Institute of Scientific and Technical Information of China (English)

    XINZi-Hua; WEIGuo-Zhu; LIANGYa-Qiu; ZHANGQi

    2004-01-01

    The magnetic properties of the mixed ferro-ferrimagnetic compounds with (AxB1-x)yC, where A, B,and C are three different magnetic ions and form three different sublattices, are studied by using the standardmean-field theory. The phase diagram which is related to experimental work of molecule-based ferro-ferrimagnet(NiⅡxMnⅡ1-x)1.5[CrⅢ(CN)6] · zH2O is obtained. The magnetization curves, internal energy, and specific heat of thesame mixed (AxB1-x)y C system are also investigated.

  7. Practical chiral alcohol manufacture using ketoreductases.

    Science.gov (United States)

    Huisman, Gjalt W; Liang, Jack; Krebber, Anke

    2010-04-01

    Over the past two years the application of ketoreductases in the commercial synthesis of chiral alcohols has undergone a revolution. Biocatalysts are now often the preferred catalyst for the synthesis of chiral alcohols via ketone reduction and are displacing reagents and chemocatalysts that only recently were considered break-through process solutions themselves. Tailor-made enzymes can now be generated from advanced, non-natural variants using HTP screening and modern molecular biology techniques. At the same time, global economic and environmental pressures direct industrial process development toward versatile platforms that can be applied to the different stages of product development. We will discuss the technologies that have emerged over the past years that have guided biocatalysis from the bottom of the toolbox, to the power tool of choice. PMID:20071211

  8. Mechanically generated surface chirality at the nanoscale.

    Science.gov (United States)

    Ferjani, Sameh; Choi, Yoonseuk; Pendery, Joel; Petschek, Rolfe G; Rosenblatt, Charles

    2010-06-25

    A substrate coated with an achiral polyimide alignment layer was scribed bidirectionally with the stylus of an atomic force microscope to create an easy axis for liquid crystal orientation. The resulting noncentrosymmetric topography resulted in a chiral surface that manifests itself at the molecular level. To show this unambiguously, a planar-aligned negative dielectric aniostropy achiral nematic liquid crystal was placed in contact with the surface and subjected to an electric field E. The nematic director was found to undergo an azimuthal rotation approximately linear in E. This so-called "surface electroclinic effect" is a signature of surface chirality and was not observed when the polyimide was treated for a centrosymmetric topography, and therefore was nonchiral. PMID:20867414

  9. Canted-to-canted singular points in ferrimagnetic polycrystalline magnetization curves

    International Nuclear Information System (INIS)

    The study of singularities in the magnetization curve of magnetic materials is since a long time a well known tool to gain insight into the material properties. Such singularities are usually due to discontinuous magnetization processes related to magnetic anisotropy, therefore an ideal investigation scheme would comprise magnetization measurements along the symmetry axis of a single crystal. As a matter of fact, one has to often deal with polycrystalline samples: in that case, however, the singularities can still be detected at the same positions as for the single crystal case. In this paper we focus on ferrimagnetic materials with uniaxial magnetic anisotropy. After recalling how theory allows us to calculate the critical fields at which singularities occur when the magnetic field is applied along a symmetry direction, we show that a new type of singular point not yet reported in the literature can exist. Such new singularity appears only in polycrystalline samples. We derive its analytical expression and we also show that, in spite of the need to overcome the exchange interaction, combinations of the material parameters can occur for which it falls inside experimentally accessible region. - Highlights: • We consider singularities in single crystal ferrimagnetic magnetization curves. • In polycrystalline samples a new singularity not yet reported in the literature occurs. • We derive analytical expressions describing such new singular point. • Computer simulations are shown to gain more insight into the singularity behavior. • The obtained results affect the interpretation of experimental magnetization curves

  10. Ferrimagnetic DyCo5 Nanostructures for Bits in Heat-Assisted Magnetic Recording

    Science.gov (United States)

    Ünal, A. A.; Valencia, S.; Radu, F.; Marchenko, D.; Merazzo, K. J.; Vázquez, M.; Sánchez-Barriga, J.

    2016-06-01

    Increasing the magnetic data recording density requires reducing the size of the individual memory elements of a recording layer as well as employing magnetic materials with temperature-dependent functionalities. Therefore, we predict that the near future of magnetic data storage technology involves a combination of energy-assisted recording on nanometer-scale magnetic media. We present the potential of heat-assisted magnetic recording on a patterned sample; a ferrimagnetic alloy composed of a rare-earth and a transition metal DyCo5, which is grown on a hexagonal-ordered nanohole array membrane. The magnetization of the antidot array sample is out-of-plane oriented at room temperature and rotates towards in plane upon heating above its magnetic anisotropy reorientation temperature (TR) of 350 K, just above room temperature. Upon cooling back to room temperature (below TR), we observe a well-defined and unexpected in-plane magnetic domain configuration modulating with 45 nm. We discuss the underlying mechanisms giving rise to this behavior by comparing the magnetic properties of the patterned sample with the ones of its extended thin-film counterpart. Our results pave the way for future applications of ferrimagnetic antidot arrays of superior functionality in magnetic nanodevices near room temperature.

  11. Silica Encapsulation of Ferrimagnetic Zinc Ferrite Nanocubes Enabled by Layer-by-layer Polyelectrolyte Deposition

    Science.gov (United States)

    Park, Jooneon; Porter, Marc D.; Granger, Michael C.

    2016-01-01

    Stable suspensions of magnetic nanoparticles (MNPs) with large magnetic moment, m, per particle have tremendous utility in a wide range of biological applications. However, due to the strong magnetic coupling interactions often present in these systems, it is challenging to stabilize individual, high moment, ferro- and ferrimagnetic nanoparticles. A novel approach to encapsulate large, i.e., >100 nm, ferrimagnetic zinc ferrite nanocubes (ZFNCs) with silica after an intermediary layer-by-layer polyelectrolyte deposition step is described in this paper. The seed ZFNCs are uniform in shape and size and have high saturation mass magnetic moment (σs ~100 emu/g, m~4×10−13 emu/particle at 150 Oe). For the MNP system described within, successful silica encapsulation and creation of discrete ZFNCs were realized only after depositing polyelectrolyte multilayers composed of alternating polyallylamine and polystyrene sulfonate. Without the intermediary polyelectrolyte layers, magnetic dipole-dipole interactions led to the formation of linearly chained ZFNCs embedded in a silica matrix. Characterization of particle samples was performed by electron microscopy, energy-dispersive X-ray spectroscopy, infrared spectroscopy, powder X-ray diffraction, dynamic light scattering (hydrodynamic size and ζ-potential), and vibrating sample magnetometry. The results of these characterizations, which were performed after each of the synthetic steps, and synthetic details are presented. PMID:25756216

  12. Possible martensitic transformation and ferrimagnetic properties in Heusler alloy Mn{sub 2}NiSn

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Ying-Ni, E-mail: duanyingni@163.com [Department of Medical Engineering and Technology, Xinjiang Medical University, Urumqi 830011, Xinjiang (China); Fan, Xiao-Xi; Kutluk, Abdugheni [Department of Medical Engineering and Technology, Xinjiang Medical University, Urumqi 830011, Xinjiang (China); Du, Xiu-Juan [School of Applied Science, Taiyuan University of Science and Technology, Taiyuan 030024, Shanxi (China); Zhang, Zheng-Wei [Chemistry and Chemical Engineering Laboratory, The Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011, Xinjiang (China); Song, Yu-Ling [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, Henan (China)

    2015-07-15

    The electronic structure and magnetic properties of Hg{sub 2}CuTi-type Mn{sub 2}NiSn have been studied by performing the first-principle calculations. It is found that the phase transformation from the cubic to the tetragonal structure reduces the total energy, indicating that the martensitic phase is more stable and the phase transition from austenite to martensite may happen at low temperature for Hg{sub 2}CuTi-type Mn{sub 2}NiSn. Concerning the magnetism of Hg{sub 2}CuTi-type Mn{sub 2}NiSn, both austenitic and martensitic phases are suggested to be ferrimagnets. Furthermore, martensitic transformation decreases the magnetic moment per formula unit compared with austenitic phase. The results are helpful to accelerate the use of Mn{sub 2}NiSn alloys in the series for magnetic shape memory applications. - Highlights: • It is found that the phase transition from austenite to martensite may happen at low temperature for Mn{sub 2}NiSn with the Hg{sub 2}CuTi-type structure. • Both austenitic and martensitic Mn{sub 2}NiSn are ferrimagnets. • Martensitic transformation decreases the magnetization.

  13. Detection limits for ferrimagnetic particle concentrations using magnetic resonance imaging based proton transverse relaxation rate measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pardoe, H [School of Physics, University of Western Australia, Crawley, Perth, WA 6009 (Australia); Chua-anusorn, W [School of Physics, University of Western Australia, Crawley, Perth, WA 6009 (Australia); Pierre, T G St [School of Physics, University of Western Australia, Crawley, Perth, WA 6009 (Australia); Dobson, J [Department of Biomedical Engineering and Medical Physics, Centre for Science and Technology in Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent, ST4 7QB (United Kingdom)

    2003-03-21

    A clinical magnetic resonance imaging (MRI) system was used to measure proton transverse relaxation rates (R{sub 2}) in agar gels with varying concentrations of ferrimagnetic iron oxide nanoparticles in a field strength of 1.5 T. The nanoparticles were prepared by coprecipitation of ferric and ferrous ions in the presence of either dextran or polyvinyl alcohol. The method of preparation resulted in loosely packed clusters (dextran) or branched chains (polyvinyl alcohol) of particles containing of the order of 600 and 400 particles, respectively. For both methods of particle preparation, concentrations of ferrimagnetic iron in agar gel less than 0.01 mg ml{sup -1} had no measurable effect on the value of R{sub 2} for the gel. The results indicate that MRI-based R{sub 2} measurements using 1.5 T clinical scanners are not quite sensitive enough to detect the very low concentrations of nanoparticulate biogenic magnetite reported in human brain tissue. (note)

  14. Spin time-relaxation within strongly coupled paramagnetic systems exhibiting paramagnetic-ferrimagnetic transitions

    CERN Document Server

    Chahid, M

    2000-01-01

    The purpose of the present work is a quantitative study of the spin time relaxation within superweak ferrimagnetic materials exhibiting a paramagnetic-ferrimagnetic transition, when the temperature is changed from an initial value T sub i to a final one T sub f very close to the critical temperature T sub c. From a magnetic point of view, the material under investigation is considered to be made of two strongly coupled paramagnetic sublattices of respective moments phi (cursive,open) Greek and psi. Calculations are made within a Landau mean-field theory, whose free energy involves, in addition to quadratic and quartic terms in both moments phi (cursive,open) Greek and psi, a lowest-order coupling - Cphi (cursive,open) Greek psi, where C<0 stands for the coupling constant measuring the interaction between the two sublattices. We first determine the time dependence of the shifts of the order parameters delta phi (cursive,open) Greek and delta psi from the equilibrium state. We find that this time dependence ...

  15. The phase structure of a chirally invariant lattice Higgs-Yukawa model. Numerical simulations

    International Nuclear Information System (INIS)

    The phase diagram of a chirally invariant lattice Higgs-Yukawa model is explored by means of numerical simulations. The results revealing a rich phase structure are compared to analytical large Nf calculations which we performed earlier. The analytical and numerical results are in excellent agreement at large values of Nf. In the opposite case the large Nf computation still gives a good qualitative description of the phase diagram. In particular we find numerical evidence for the predicted ferrimagnetic phase at intermediate values of the Yukawa coupling constant and for the symmetric phase at strong Yukawa couplings. Emphasis is put on the finite size effects which can hide the existence of the latter symmetric phase. (orig.)

  16. Chiral Crystal Growth under Grinding

    OpenAIRE

    Saito, Yukio; Hyuga, Hiroyuki

    2008-01-01

    To study the establishment of homochirality observed in the crystal growth experiment of chiral molecules from a solution under grinding, we extend the lattice gas model of crystal growth as follows. A lattice site can be occupied by a chiral molecule in R or S form, or can be empty. Molecules form homoclusters by nearest neighbor bonds. They change their chirality if they are isolated monomers in the solution. Grinding is incorporated by cutting and shafling the system randomly. It is shown ...

  17. Spiral Galaxies as Chiral Objects?

    CERN Document Server

    Capozziello, S; Capozziello, Salvatore; Lattanzi, Alessandra

    2005-01-01

    Spiral galaxies show axial symmetry and an intrinsic 2D-chirality. Environmental effects can influence the chirality of originally isolated stellar systems and a progressive loss of chirality can be recognised in the Hubble sequence. We point out a preferential modality for genetic galaxies as in microscopic systems like aminoacids, sugars or neutrinos. This feature could be the remnant of a primordial symmetry breaking characterizing systems at all scales.

  18. Chiral dynamics and baryon resonances

    OpenAIRE

    Hyodo, Tetsuo

    2010-01-01

    The structure of baryon resonance in coupled-channel meson-baryon scattering is studied from the viewpoint of chiral dynamics. The meson-baryon scattering amplitude can be successfully described together with the properties of the resonance in the scattering, by implementing the unitarity condition for the amplitude whose low energy structure is constrained by chiral theorem. Recently, there have been a major progress in the study of the structure of the resonance in chiral dynamics. We revie...

  19. A Chiral Granular Gas

    Science.gov (United States)

    Tsai, J.-C.; Ye, Fangfu; Rodriguez, Juan; Gollub, J. P.; Lubensky, T. C.

    2005-05-01

    Inspired by rattleback toys, we created small chiral wires that rotate in a preferred direction on a vertically oscillating platform and quantified their motion with experiment and simulation. We demonstrate experimentally that angular momentum of rotation about particle centers of mass is converted to collective angular momentum of center-of-mass motion in a granular gas of these wires, and we introduce a continuum model that explains our observations.

  20. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    Science.gov (United States)

    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.

  1. Generalized simplicial chiral models

    CERN Document Server

    Alimohammadi, M

    2000-01-01

    Using the auxiliary field representation of the simplicial chiral models on a (d-1)-dimensional simplex, we generalize the simplicial chiral models by replacing the term Tr$(AA^{\\d})$ in the Lagrangian of these models, by an arbitrary class function of $AA^{\\d}; V(AA^{\\d})$. This is the same method that has been 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 ". With the help of the results of one-link integral over a U(N) matrix, we compute the large-N saddle-point equations for eigenvalue density function $\\ro (z)$ in the weak ($\\b >\\b_c$) and strong ($\\b <\\b_c$) regions. In d=2, where the model somehow relates to gYM_2 theory, we solve the saddle-point equations and find $\\ro (z)$ in two region, and calculate the explicit value of critical point $\\b_c$ for $V(B)=TrB^n (B=AA^{\\d})$. For $V(B)=Tr B^2,Tr B^3$ and Tr$B^4$, we study the critical behaviour of the model at d=2, and by calculating t...

  2. Chiral nuclear thermodynamics

    CERN Document Server

    Fiorilla, Salvatore; Weise, Wolfram

    2011-01-01

    We calculate the equation of state of nuclear matter for arbitrary isospin-asymmetry up to three loop order in the free energy density in the framework of in-medium chiral perturbation theory. In our approach 1\\pi- and 2\\pi-exchange dynamics with the inclusion of the \\Delta-isobar excitation as an explicit degree of freedom, corresponding to the long- and intermediate-range correlations, are treated explicitly. Few contact terms fixed to reproduce selected known properties of nuclear matter encode the short-distance physics. Two-body as well as three-body forces are systematically included. We find a critical temperature of about 15 MeV for symmetric nuclear matter. We investigate the dependence of the liquid-gas first-order phase transition on isospin-asymmetry. In the same chiral framework we calculate the chiral condensate of isospin-symmetric nuclear matter at finite temperatures. The contribution of the \\Delta-isobar excitation is essential for stabilizing the condensate. As a result, we find no indicati...

  3. The chiral magnetic effect in hydrodynamical approach

    OpenAIRE

    Sadofyev, A. V.; Isachenkov, M. V.

    2010-01-01

    In quark-gluon plasma nonzero chirality can be induced by the chiral anomaly. When a magnetic field is applied to a system with nonzero chirality an electromagnetic current is induced along the magnetic field. This phenomenon is called the chiral magnetic effect. In this paper appearance of the chiral magnetic effect in hydrodynamical approximation is shown. We consider a hydrodynamical model for chiral liquid with two independent currents of left and right handed particles in the presence of...

  4. Chiral discrimination in optical trapping and manipulation

    Science.gov (United States)

    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.

  5. Discovery of the interstellar chiral molecule propylene oxide (CH_3CHCH_2O)

    OpenAIRE

    McGuire, Brett A.; Carroll, P. Brandon; Loomis, Ryan A.; Finneran, Ian A.; Jewell, Philip R.; Remijan, Anthony J.; Blake, Geoffrey A.

    2016-01-01

    Life on Earth relies on chiral molecules—that is, species not superimposable on their mirror images. This manifests itself in the selection of a single molecular handedness, or homochirality, across the biosphere. We present the astronomical detection of a chiral molecule, propylene oxide (CH_3CHCH_2O), in absorption toward the Galactic center. Propylene oxide is detected in the gas phase in a cold, extended molecular shell around the embedded, massive protostellar clusters in the Sagittarius...

  6. Discovery of the Interstellar Chiral Molecule Propylene Oxide (CH$_3$CHCH$_2$O)

    CERN Document Server

    McGuire, Brett A; Loomis, Ryan A; Finneran, Ian A; Jewell, Philip R; Remijan, Anthony J; Blake, Geoffrey A

    2016-01-01

    Life on Earth relies on chiral molecules, that is, species not superimposable on their mirror images. This manifests itself in the selection of a single molecular handedness, or homochirality, across the biosphere. We present the astronomical detection of a chiral molecule, propylene oxide (CH$_3$CHCH$_2$O), in absorption toward the Galactic Center. Propylene oxide is detected in the gas phase in a cold, extended molecular shell around the embedded, massive protostellar clusters in the Sagittarius B2 star-forming region. This material is representative of the earliest stage of solar system evolution in which a chiral molecule has been found.

  7. Discovery of the interstellar chiral molecule propylene oxide (CH3CHCH2O)

    Science.gov (United States)

    McGuire, Brett A.; Carroll, P. Brandon; Loomis, Ryan A.; Finneran, Ian A.; Jewell, Philip R.; Remijan, Anthony J.; Blake, Geoffrey A.

    2016-06-01

    Life on Earth relies on chiral molecules—that is, species not superimposable on their mirror images. This manifests itself in the selection of a single molecular handedness, or homochirality, across the biosphere. We present the astronomical detection of a chiral molecule, propylene oxide (CH3CHCH2O), in absorption toward the Galactic center. Propylene oxide is detected in the gas phase in a cold, extended molecular shell around the embedded, massive protostellar clusters in the Sagittarius B2 star-forming region. This material is representative of the earliest stage of solar system evolution in which a chiral molecule has been found.

  8. Discovery of the interstellar chiral molecule propylene oxide (CH₃CHCH₂O).

    Science.gov (United States)

    McGuire, Brett A; Carroll, P Brandon; Loomis, Ryan A; Finneran, Ian A; Jewell, Philip R; Remijan, Anthony J; Blake, Geoffrey A

    2016-06-17

    Life on Earth relies on chiral molecules-that is, species not superimposable on their mirror images. This manifests itself in the selection of a single molecular handedness, or homochirality, across the biosphere. We present the astronomical detection of a chiral molecule, propylene oxide (CH3CHCH2O), in absorption toward the Galactic center. Propylene oxide is detected in the gas phase in a cold, extended molecular shell around the embedded, massive protostellar clusters in the Sagittarius B2 star-forming region. This material is representative of the earliest stage of solar system evolution in which a chiral molecule has been found. PMID:27303055

  9. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    Science.gov (United States)

    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.

  10. Chiral Dynamics 2006

    Science.gov (United States)

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

    2007-10-01

    pt. A. Plenary session. Opening remarks: experimental tests of chiral symmetry breaking / A. M. Bernstein. [Double pie symbols] scattering / H. Leutwyler. Chiral effective field theory in a [Triangle]-resonance region / V. Pascalutsa. Some recent developments in chiral perturbation theory / Ulf-G. Mei ner. Chiral extrapolation and nucleon structure from the lattice / R.D. Young. Recent results from HAPPEX / R. Michaels. Chiral symmetries and low energy searches for new physics / M.J. Ramsey-Musolf. Kaon physics: recent experimental progress / M. Moulson. Status of the Cabibbo angle / V. Cirigliano. Lattice QCD and nucleon spin structure / J.W. Negele. Spin sum rules and polarizabilities: results from Jefferson lab / J-P Chen. Compton scattering and nucleon polarisabilities / Judith A. McGovern. Virtual compton scattering at MIT-bates / R. Miskimen. Physics results from the BLAST detector at the BATES accelerator / R.P. Redwine. The [Pie sympbol]NN system, recent progress / C. Hanhart. Application of chiral nuclear forces to light nuclei / A. Nogga. New results on few-body experiments at low energy / Y. Nagai. Few-body lattice calculations / M.J. Savage. Research opportunities at the upgraded HI?S facility / H.R. Weller -- pt. B. Goldstone boson dynamics. Working group summary: Goldstone Boson dynamics / G. Colangelo and S. Giovannella. Recent results on radiative Kaon decays from NA48 and NA48/2 / S.G. López. Cusps in K-->3 [Pie symbol] decays / B. Kubis. Recent KTeV results on radiative Kaon decays / M.C. Ronquest. The [Double pie symbols] scattering amplitude / J.R. Peláez. Determination of the Regge parameters in the [Double pie symbols] scattering amplitude / I. Caprini. e+e- Hadronic cross section measurement at DA[symbol]NE with the KLOE detector / P. Beltrame. Measurement of the form factors of e+e- -->2([Pie symbol]+[Pie symbol]-), pp and the resonant parameters of the heavy charmonia at BES / H. Hu. Measurement of e+e- multihadronic cross section below 4

  11. Chiromers: conformation-driven mirror-image supramolecular chirality isomerism identified in a new class of helical rosette nanotubes

    Science.gov (United States)

    Hemraz, Usha D.; El-Bakkari, Mounir; Yamazaki, Takeshi; Cho, Jae-Young; Beingessner, Rachel L.; Fenniri, Hicham

    2014-07-01

    Rosette nanotubes are biologically inspired nanostructures, formed through the hierarchical organization of a hybrid DNA base analogue (G∧C), which features hydrogen-bonding arrays of guanine and cytosine. Several twin-G∧C motifs functionalized with chiral moieties, which undergo a self-assembly process under methanolic and aqueous conditions to produce helical rosette nanotubes (RNTs), were synthesized and characterized. The built-in molecular chirality in the twin-G∧C building blocks led to the supramolecular chirality exhibited by the RNTs, as evidenced by the CD activity. Depending on the motifs and environmental conditions, mirror-image supramolecular chirality due to absolute molecular chirality, solvent-induced and structure-dependent supramolecular chirality inversion, and pH-controlled chiroptical switching were observed.Rosette nanotubes are biologically inspired nanostructures, formed through the hierarchical organization of a hybrid DNA base analogue (G∧C), which features hydrogen-bonding arrays of guanine and cytosine. Several twin-G∧C motifs functionalized with chiral moieties, which undergo a self-assembly process under methanolic and aqueous conditions to produce helical rosette nanotubes (RNTs), were synthesized and characterized. The built-in molecular chirality in the twin-G∧C building blocks led to the supramolecular chirality exhibited by the RNTs, as evidenced by the CD activity. Depending on the motifs and environmental conditions, mirror-image supramolecular chirality due to absolute molecular chirality, solvent-induced and structure-dependent supramolecular chirality inversion, and pH-controlled chiroptical switching were observed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00340c

  12. Observation of an anisotropic Dirac cone reshaping and ferrimagnetic spin polarization in an organic conductor

    Science.gov (United States)

    Hirata, Michihiro; Ishikawa, Kyohei; Miyagawa, Kazuya; Tamura, Masafumi; Berthier, Claude; Basko, Denis; Kobayashi, Akito; Matsuno, Genki; Kanoda, Kazushi

    2016-08-01

    The Coulomb interaction among massless Dirac fermions in graphene is unscreened around the isotropic Dirac points, causing a logarithmic velocity renormalization and a cone reshaping. In less symmetric Dirac materials possessing anisotropic cones with tilted axes, the Coulomb interaction can provide still more exotic phenomena, which have not been experimentally unveiled yet. Here, using site-selective nuclear magnetic resonance, we find a non-uniform cone reshaping accompanied by a bandwidth reduction and an emergent ferrimagnetism in tilted Dirac cones that appear on the verge of charge ordering in an organic compound. Our theoretical analyses based on the renormalization-group approach and the Hubbard model show that these observations are the direct consequences of the long-range and short-range parts of the Coulomb interaction, respectively. The cone reshaping and the bandwidth renormalization, as well as the magnetic behaviour revealed here, can be ubiquitous and vital for many Dirac materials.

  13. Metrological Performance of a Ferrimagnetic Resonance Marker for the Field Control of the CERN Proton Synchrotron

    CERN Document Server

    Arpaia, P; Caspers, F; Golluccio, G; Oberson, D

    2012-01-01

    In particle accelerators, “field markers” provide a digital trigger when the magnetic field crosses a given threshold. In this paper, the metrological characterization of a magnetic field marker, based on a ferrimagnetic resonance transducer referencing the flux sensed by a coil, is reported. The experimental results of a validation test campaign at the European Organization for Nuclear Research (CERN) to test the marker in static as well as fast ramping fields (up to 2.5 T/s) are illustrated. The repeatability of ±4 μT attained in the range (60 to 100) mT is very promising to increase the performance of the Proton Synchrotron accelerator at CERN.

  14. Low loss spin wave resonances in organic-based ferrimagnet vanadium tetracyanoethylene thin films

    Science.gov (United States)

    Zhu, Na; Zhang, Xufeng; Froning, I. H.; Flatté, Michael E.; Johnston-Halperin, E.; Tang, Hong X.

    2016-08-01

    We experimentally demonstrate high quality factor spin wave resonances in an encapsulated thin film of the organic-based ferrimagnet vanadium tetracyanoethylene ( V [TC N E ] x ˜2 ) coated on an a-plane sapphire substrate by low temperature chemical vapor deposition. The thickness standing wave modes are observed in a broad frequency range (1 GHz-5 GHz) with high quality factor exceeding 3200 in ambient air at room temperature, rivaling those of inorganic magnetic materials. The exchange constant of V [TC N E ] x ˜2 , a crucial material parameter for future study and device design of the V [TC N E ] x ˜2 , is extracted from the measurement with a value of (4.61 ±0.35 ) ×10-16 m2 . Our result establishes the feasibility of using organic-based materials for building hybrid magnonic devices and circuits.

  15. Temperature effect on the magnetic properties of the coprecipitation derived ferrimagnetic glass-ceramics

    International Nuclear Information System (INIS)

    Ferrimagnetic glass-ceramic materials are promising candidates for destruction of cancerous cells by hysteresis loss, as a consequence of the increase of the local temperature when an alternating magnetic field is applied. The glass-ceramics prepared in this work contain magnetite and hematite crystals in a glassy matrix. They can be prepared by melting the coprecipitation-derived precursors at temperatures higher than 1400 deg. C. The influence of the melting temperature on the magnetic properties of these glass-ceramics has been analysed. Room temperature hysteresis cycles in quasi-static conditions were performed using two different magnetic field, one of 12 kOe, and the other one of 500 Oe. The heat generation was estimated from calorimetric measurements, using a magnetic induction furnace. The magnetic hysteresis parameters are strongly affected by the glass-ceramics microstructure, which is influenced by the melting temperature

  16. First-principles study on the ferrimagnetic half-metallic Mn2FeAs alloy

    Science.gov (United States)

    Qi, Santao; Zhang, Chuan-Hui; Chen, Bao; Shen, Jiang; Chen, Nanxian

    2015-05-01

    Mn-based full-Heusler alloys are kinds of promising candidates for new half-metallic materials. Basing on first principles, the electronic structures and magnetic properties of the Mn2FeAs full-Heusler alloy have been investigated in detail. The Hg2CuTi-type Mn2FeAs compound obeys the Slater-Pauling rule, while the anti-parallel alignment atomic magnetic moments of Mn locating at different sites indicate it a ferrimagnetic alloy. The calculated spin-down bands behave half-metallic character, exhibiting a direct gap of 0.46 eV with a 100% spin polarization at the Fermi level. More studies show the compound would maintain half-metallic nature in a large range of variational lattice constants. We expect that our calculated results may trigger Mn2FeAs applying in the future spintronics field.

  17. Magnetization reversal and ferrimagnetism in Pr,1–NdMnO3

    Indian Academy of Sciences (India)

    Sanjay Biswas; Momin Hossain Khan; Sudipta Pal

    2014-06-01

    Detailed magnetic properties of Pr1–NdMnO3 ( = 0.3, 0.5 and 0.7) have been reported. All the samples crystallize in orthorhombic perovskite structure with Pnma space group. Magnetization measurements under field cooled (FC) protocal reveal magnetization reversal at low temperatures and low magnetic field. This indicates clear evidence of two magnetic sublattices aligned opposite to each other. There is a well-defined maximum around 48 K in the = 0.7 sample (i.e. Pr0.3Nd0.7MnO3) in the ' value which is identified as paramagnetic to ferrimagnetic transition. The peak value shifts to higher temperature with decrease of and width of the maximum broadened. It is also observable that with decrease of Nd, both the value of ' and " decrease. An attempt is made to explain the magnetization reversal within the framework of available models

  18. Ferrimagnetism in Mn{sub x}V{sub 1-x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. [Victoria University of Technology, VIC (Australia). School of Communications and Informatics; Hicks, T.J. [Monash University, Clayton, VIC (Australia). Department of Physics; Studer, A.J.; Kennedy, S.J. [Australian Nuclear Science and technology Organisation, Lucas heights , NSW (Australia)

    1998-12-31

    Full text: The magnetic properties of MnV alloys near the equiatomic concentration have been investigated using magnetic susceptibility and neutron powder diffraction. Rapidly cooled body centred cubic alloys near the equiatomic concentration are confirmed as very weakly ferrimagnetic with average local moment of the order of 0.05 {mu}{sub B} per atom and average ordered moments of order 0.02 {mu}{sub B} per atom. The degree of atomic and magnetic order can be greatly enhanced by annealing these alloys supporting the view that the ordered moments are associated with CsCl type atomic short range order. Evidence is presented that the moment is not associated with impurities or any of the multitude of magnetically ordered mixed manganese vanadium oxides

  19. Ferrimagnetic order in the insulating Sr3Fe2ReO9 double perovskite

    International Nuclear Information System (INIS)

    A new iron(III)/rhenium(VI) double perovskite oxide, Sr3Fe2ReO9, has been synthesized in polycrystalline form at 1200 C by solid-state reaction from citrate precursors. The Rietveld analysis of the synchrotron X-ray powder diffraction pattern shows that this compound, at 300 K, has orthorhombic symmetry (S.G.: Immm), with a=5.56733(1) A, b=5.56796(1) A and c=7.90224(2) A. The refinement of the relative Fe/Re occupancies of each B site reveals the presence of a partial cationic order. At high temperatures, the magnetic susceptibility of the Sr3Fe2ReO9 is well described as a paramagnet with ferrimagnetic correlations. Below 450 K, the system displays a spontaneous magnetization, and hysteresis loops are observed

  20. Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy

    Science.gov (United States)

    Jeong, Jaewoo; Ferrante, Yari; Faleev, Sergey V.; Samant, Mahesh G.; Felser, Claudia; Parkin, Stuart S. P.

    2016-01-01

    Although high-tunnelling spin polarization has been observed in soft, ferromagnetic, and predicted for hard, ferrimagnetic Heusler materials, there has been no experimental observation to date of high-tunnelling magnetoresistance in the latter. Here we report the preparation of highly textured, polycrystalline Mn3Ge films on amorphous substrates, with very high magnetic anisotropy fields exceeding 7 T, making them technologically relevant. However, the small and negative tunnelling magnetoresistance that we find is attributed to predominant tunnelling from the lower moment Mn-Ge termination layers that are oppositely magnetized to the higher moment Mn-Mn layers. The net spin polarization of the current reflects the different proportions of the two distinct termination layers and their associated tunnelling matrix elements that result from inevitable atomic scale roughness. We show that by engineering the spin polarization of the two termination layers to be of the same sign, even though these layers are oppositely magnetized, high-tunnelling magnetoresistance is possible.

  1. Large spin-wave bullet in a ferrimagnetic insulator driven by spin Hall effect.

    Energy Technology Data Exchange (ETDEWEB)

    Jungfleisch, M. B.; Zhang, W.; Sklenar, J.; Ding, J.; Jiang, W.; Chang, Houchen; Fradin, F. Y.; Pearson, J. E.; Ketterson, J. B.; Novosad, V.; Wu, Mingzhong; Hoffmann, A.

    2016-02-01

    Due to its transverse nature, spin Hall effects (SHE) provide the possibility to excite and detect spin currents and magnetization dynamics even in magnetic insulators. Magnetic insulators are outstanding materials for the investigation of nonlinear phenomena and for novel low power spintronics applications because of their extremely low Gilbert damping. Here, we report on the direct imaging of electrically driven spin-torque ferromagnetic resonance (ST-FMR) in the ferrimagnetic insulator Y3Fe5O12 based on the excitation and detection by SHEs. The driven spin dynamics in Y3Fe5O12 is directly imaged by spatially-resolved microfocused Brillouin light scattering (BLS) spectroscopy. Previously, ST-FMR experiments assumed a uniform precession across the sample, which is not valid in our measurements. A strong spin-wave localization in the center of the sample is observed indicating the formation of a nonlinear, self-localized spin-wave `bullet'.

  2. Large Spin-Wave Bullet in a Ferrimagnetic Insulator Driven by the Spin Hall Effect.

    Science.gov (United States)

    Jungfleisch, M B; Zhang, W; Sklenar, J; Ding, J; Jiang, W; Chang, H; Fradin, F Y; Pearson, J E; Ketterson, J B; Novosad, V; Wu, M; Hoffmann, A

    2016-02-01

    Because of its transverse nature, spin Hall effects (SHE) provide the possibility to excite and detect spin currents and magnetization dynamics even in magnetic insulators. Magnetic insulators are outstanding materials for the investigation of nonlinear phenomena and for novel low power spintronics applications because of their extremely low Gilbert damping. Here, we report on the direct imaging of electrically driven spin-torque ferromagnetic resonance (ST-FMR) in the ferrimagnetic insulator Y_{3}Fe_{5}O_{12} based on the excitation and detection by SHEs. The driven spin dynamics in Y_{3}Fe_{5}O_{12} is directly imaged by spatially resolved microfocused Brillouin light scattering spectroscopy. Previously, ST-FMR experiments assumed a uniform precession across the sample, which is not valid in our measurements. A strong spin-wave localization in the center of the sample is observed indicating the formation of a nonlinear, self-localized spin-wave "bullet". PMID:26894733

  3. Longitudinal spin dynamics in ferrimagnets: Multiple spin wave nature of longitudinal spin excitations

    Science.gov (United States)

    Krivoruchko, V. N.

    2016-08-01

    Motivated by the existing controversy about the physical mechanisms that govern longitudinal magnetization dynamics under the effect of ultrafast laser pulses, in this paper we study the microscopic model of longitudinal spin excitations in a two-sublattice ferrimagnet using the diagrammatic technique for spin operators. The diagrammatic approach provides us with an efficient procedure to derive graphical representations for perturbation expansion series for different spin Green's functions and thus to overcome limitations typical for phenomenological approaches. The infinite series involving all distinct loops built from spin wave propagators are summed up. These result in an expression for the longitudinal spin susceptibility χz z(q ,ω ) applicable in all regions of frequency ω and wave vector q space beyond the hydrodynamical and critical regimes. A strong renormalization of the longitudinal spin oscillations due to processes of virtual creation and annihilation of transverse spin waves has been found. We have shown that the spectrum of longitudinal excitations consists of a quasirelaxation mode forming a central peak in χz z(q ,ω ) and two (acoustic and exchange) precessionlike modes. As the main result, it is predicted that both acoustic and exchange longitudinal excitations are energetically above similar modes of transverse spin waves at the same temperature and wave vector. The existence of the exchange longitudinal mode at such frequencies can result in a new form of excitation behavior in ferrimagnetic system, which could be important for understanding the physics of nonequilibrium magnetic dynamics under the effect of ultrafast laser pulses in multisublattice magnetic materials.

  4. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility.

    Science.gov (United States)

    Verné, Enrica; Bruno, Matteo; Miola, Marta; Maina, Giovanni; Bianco, Carlotta; Cochis, Andrea; Rimondini, Lia

    2015-08-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO2-Na2O-CaO-P2O5-FeO-Fe2O3 and contains magnetite (Fe3O4) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite - HAp - layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. PMID:26042695

  5. Quark structure of chiral solitons

    CERN Document Server

    Diakonov, D

    2004-01-01

    There is a prejudice that the chiral soliton model of baryons is something orthogonal to the good old constituent quark models. In fact, it is the opposite: the spontaneous chiral symmetry breaking in strong interactions explains the appearance of massive constituent quarks of small size thus justifying the constituent quark models, in the first place. Chiral symmetry ensures that constituent quarks interact very strongly with the pseudoscalar fields. The ``chiral soliton'' is another word for the chiral field binding constituent quarks. We show how the old SU(6) quark wave functions follow from the ``soliton'', however, with computable relativistic corrections and additional quark-antiquark pairs. We also find the 5-quark wave function of the exotic baryon Theta+.

  6. Mass-Selective Chiral Analysis.

    Science.gov (United States)

    Boesl, Ulrich; Kartouzian, Aras

    2016-06-12

    Three ways of realizing mass-selective chiral analysis are reviewed. The first is based on the formation of diastereomers that are of homo- and hetero- type with respect to the enantiomers of involved chiral molecules. This way is quite well-established with numerous applications. The other two ways are more recent developments, both based on circular dichroism (CD). In one, conventional or nonlinear electronic CD is linked to mass spectrometry (MS) by resonance-enhanced multiphoton ionization. The other is based on CD in the angular distribution of photoelectrons, which is measured in combination with MS via photoion photoelectron coincidence. Among the many important applications of mass-selective chiral analysis, this review focuses on its use as an analytical tool for the development of heterogeneous enantioselective chemical catalysis. There exist other approaches to combine chiral analysis and mass-selective detection, such as chiral chromatography MS, which are not discussed here. PMID:27070181

  7. Dileptons and Chiral Symmetry Restoration

    CERN Document Server

    Hohler, P M

    2015-01-01

    We report on recent work relating the medium effects observed in dilepton spectra in heavy-ion collisions to potential signals of chiral symmetry restoration. The key connection remains the approach to spectral function degeneracy between the vector-isovector channel with its chiral partner, the axialvector-isovector channel. Several approaches are discussed to elaborate this connection, namely QCD and Weinberg sum rules with input for chiral order parameters from lattice QCD, and chiral hadronic theory to directly evaluate the medium effects of the axialvector channel and the pertinent pion decay constant as function of temperature. A pattern emerges where the chiral mass splitting between rho and a_1 burns off and is accompanied by a strong broadening of the spectral distributions.

  8. Mass-Selective Chiral Analysis

    Science.gov (United States)

    Boesl, Ulrich; Kartouzian, Aras

    2016-06-01

    Three ways of realizing mass-selective chiral analysis are reviewed. The first is based on the formation of diastereomers that are of homo- and hetero- type with respect to the enantiomers of involved chiral molecules. This way is quite well-established with numerous applications. The other two ways are more recent developments, both based on circular dichroism (CD). In one, conventional or nonlinear electronic CD is linked to mass spectrometry (MS) by resonance-enhanced multiphoton ionization. The other is based on CD in the angular distribution of photoelectrons, which is measured in combination with MS via photoion photoelectron coincidence. Among the many important applications of mass-selective chiral analysis, this review focuses on its use as an analytical tool for the development of heterogeneous enantioselective chemical catalysis. There exist other approaches to combine chiral analysis and mass-selective detection, such as chiral chromatography MS, which are not discussed here.

  9. Room temperature chiral discrimination in paramagnetic NMR spectroscopy

    CERN Document Server

    Soncini, Alessandro

    2016-01-01

    A recently proposed theory of chiral discrimination in NMR spectroscopy based on the detection of a molecular electric polarization $\\mathbf{P}$ rotating in a plane perpendicular to the NMR magnetic field [A. D. Buckingham, J. Chem. Phys. $\\mathbf{140}$, 011103 (2014)], is here generalized to paramagnetic systems. Our theory predicts new contributions to $\\mathbf{P}$, varying as the square of the inverse temperature. Ab initio calculations for ten Dy$^{3+}$ complexes, at 293K, show that in strongly anisotropic paramagnetic molecules $\\mathbf{P}$ can be more than 1000 times larger than in diamagnetic molecules, making paramagnetic NMR chiral discrimination amenable to room temperature detection.

  10. Constructing Self-Dual Chiral Polytopes

    OpenAIRE

    Cunningham, Gabe

    2011-01-01

    An abstract polytope is chiral if its automorphism group has two orbits on the flags, such that adjacent flags belong to distinct orbits. There are still few examples of chiral polytopes, and few constructions that can create chiral polytopes with specified properties. In this paper, we show how to build self-dual chiral polytopes using the mixing construction for polytopes.

  11. Chiral fiber optical isolator

    Science.gov (United States)

    Kopp, Victor I.; Zhang, Guoyin; Zhang, Sheng; Genack, Azriel Z.; Neugroschl, Dan

    2009-02-01

    We propose an in-fiber chiral optical isolator based on chiral fiber polarizer technology and calculate its performance by incorporating the magnetic field into the scattering matrix. The design will be implemented in a special preform, which is passed through a miniature heat zone as it is drawn and twisted. The birefringence of the fiber is controlled by adjusted the diameter of a dual-core optical fiber. By adjusting the twist, the fiber can convert linear to circular polarization and reject one component of circular polarization. In the novel central portion of the isolator, the fiber diameter is large. The effective birefringence of the circular central core with high Verdet constant embedded in an outer core of slightly smaller index of refraction is small. The central potion is a non-reciprocal polarization converter which passes forward traveling left circularly polarized (LCP) light as LCP, while converting backward propagating LCP to right circularly polarized (RCP) light. Both polarizations of light traveling backwards are scattered out of the isolator. Since it is an all-glass structure, we anticipate that the isolator will be able to handle several watts of power and will be environmentally robust.

  12. Chiral symmetry and scalars

    International Nuclear Information System (INIS)

    The suggestion by Jaffe that if σ is a light q2q-bar2 state 0++ then even the fundamental chiral transformation properties of the σ becomes unclear, has stimulated much interest. Adler pointed out that in fact the seminal work on chiral symmetry via PCAC consistency, is really quite consistent with the σ being predominantly q2q-bar2. This interpretation was actually backed by subsequent work on effective Lagrangian methods for linear and non linear realizations. More recent work of Achasov suggests that intermediate four-quark states determine amplitudes involving other scalars a0(980) and f0(980) below 1 GeV, and the report by Ning Wu that study on σ meson in J/ψ → ωπ+π- continue to support a non qq-bar σ with mass as low as 390 MeV. It is also noted that more recent re-analysis of πK scattering by S. Ishida et al. together with the work of the E791 Collaboration, support the existence of the scalar κ particle with comparatively light mass as well

  13. Nonequilibrium chiral perturbation theory and disoriented chiral condensates

    CERN Document Server

    Nicola, A G

    1999-01-01

    We analyse the extension of Chiral Perturbation Theory to describe a meson gas out of thermal equilibrium. For that purpose, we let the pion decay constant be a time-dependent function and work within the Schwinger-Keldysh contour technique. A useful connection with curved space-time QFT allows to consistently renormalise the model, introducing two new low-energy constants in the chiral limit. We discuss the applicability of our approach within a Relativistic Heavy-Ion Collision environment. In particular, we investigate the formation of Disoriented Chiral Condensate domains in this model, via the parametric resonance mechanism.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Supernovae, Neutrinos and the Chirality of Amino Acids

    Directory of Open Access Journals (Sweden)

    Toshitaka Kajino

    2011-05-01

    Full Text Available 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.

  16. Supernovae, Neutrinos, and the Chirality of the Amino Acids

    CERN Document Server

    Boyd, R N; Onaka, T

    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 described. 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.

  17. Stimuli-Directed Helical Chirality Inversion and Bio-Applications

    Directory of Open Access Journals (Sweden)

    Ziyu Lv

    2016-08-01

    Full Text Available Helical structure is a sophisticated ubiquitous motif found in nature, in artificial polymers, and in supramolecular assemblies from microscopic to macroscopic points of view. Significant progress has been made in the synthesis and structural elucidation of helical polymers, nevertheless, a new direction for helical polymeric materials, is how to design smart systems with controllable helical chirality, and further use them to develop chiral functional materials and promote their applications in biology, biochemistry, medicine, and nanotechnology fields. This review summarizes the recent progress in the development of high-performance systems with tunable helical chirality on receiving external stimuli and discusses advances in their applications as drug delivery vesicles, sensors, molecular switches, and liquid crystals. Challenges and opportunities in this emerging area are also presented in the conclusion.

  18. The Development of Chiral Catalysis in Asymmetric Synthesis%手性催化在不对称合成中的发展

    Institute of Scientific and Technical Information of China (English)

    杨晓刚; 黄蓓

    2012-01-01

    介绍了手性化合物的重要性及其发展情况,从手性分子的制备、手性有机小分子催化的应用等方面总结了手性分子的研究进展,指出了手性分子的发展方向。%The importance and devopment of chiral compounds are introduced, from the preparation of chiral molecule, the application of chiral organic small molecular catalyst, the research progress of chiral molealle are summarized, the development direction of chiral molecule are pointed out.

  19. Symmetry Breaking in Chiral Ionic Liquids Evidenced by Vibrational Optical Activity.

    Science.gov (United States)

    Oulevey, Patric; Luber, Sandra; Varnholt, Birte; Bürgi, Thomas

    2016-09-19

    Ionic liquids (ILs) are receiving increasing interest for their use in synthetic laboratories and industry. Being composed of charged entities, they show a complex and widely unexplored dynamic behavior. Chiral ionic liquids (CILs) have a high potential as solvents for use in asymmetric synthesis. Chiroptical methods, owing to their sensitivity towards molecular conformation, offer unique possibilities to study the structure of these chiral ionic liquids. Raman optical activity proved particularly useful to study ionic liquids composed of amino acids and the achiral 1-ethyl-3-methylimidazolium counterion. We could substantiate, supported by selected theoretical methods, that the achiral counterion adopts an overall chiral conformation in the presence of chiral amino acid ions. These findings suggest that in the design of chiral ionic liquids for asymmetric synthesis, the structure of the achiral counter ion also has to be carefully considered.

  20. Chiral expression at the solid-liquid interface: a joint experimental and theoretical study of the self-assembly of chiral porphyrins on graphite.

    Science.gov (United States)

    Linares, Mathieu; Iavicoli, Patrizia; Psychogyiopoulou, Krystallia; Beljonne, David; De Feyter, Steven; Amabilino, David B; Lazzaroni, Roberto

    2008-09-01

    The chiral organization of an enantiopure functional molecule on an achiral surface has been studied with the aim of understanding the influence of stereogenic centers on the self-assembly in two dimensions. A chiral tetra meso-amidophenyl-substituted porphyrin containing long hydrophobic tails at the periphery of the conjugated pi-electron system was prepared for this purpose. Scanning tunneling microscopy (STM) images of the compound at the graphite-heptanol interface reveal a chiral arrangement of the molecules, with the porphyrin rows tilted by 13 degrees with respect to the normal to the graphite axes. In terms of molecular modeling, a combination of molecular dynamics simulations on systems constrained by periodic boundary conditions and on unconstrained large molecular aggregates has been applied to reach a quantitative interpretation on both the density of the layer and its orientation with respect to the graphite surface. The results show clearly that (i) the methyl groups of the stereogenic point toward the graphite surface and (ii) the porphyrin molecules self-assemble into an interdigitated structure where the alkyl chains align along one of the graphite axes and the porphyrin cores are slightly shifted with respect to one another. The direction of this shift, which defines the chirality of the monolayer, is set by the chirality of the stereogenic centers. Such an arrangement results in the formation of a dense chiral monolayer that is further stabilized by hydrogen bonding with protic solvents.

  1. Front-Form Chiral Multiplets

    CERN Document Server

    Gómez-Rocha, María

    2012-01-01

    In this article we point out that the unitary transformation that relates the chiral basis $\\{R; I J^{PC}\\}$ and the $\\{I; ^{2S+1}L_J \\}$ basis, which was already derived for canonical spin in instant form, is also applicable in light-cone representations. From the most general expression for the Clebsch-Gordan coefficients of the Poincar\\'e group one can see that the chiral limit brings the angular momentum coupling into a simple form that permits a clear relation in terms of SU(2) Clebsch-Gordan coefficients. It provides a tool of measurement of chiral symmetry in relativistic composite systems.

  2. Quarks, baryons and chiral symmetry

    CERN Document Server

    Hosaka, Atsushi

    2001-01-01

    This book describes baryon models constructed from quarks, mesons and chiral symmetry. The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction. Emphasis is placed on symmetry aspects of the theories. As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated. The text is more practical than formal; tools and ideas are explained in detail w

  3. Chiral Relaxation Time at the Chiral Crossover of Quantum Chromodynamics

    CERN Document Server

    Ruggieri, M; Chernodub, M

    2016-01-01

    We study microscopic processes responsible for chirality flips in the thermal bath of Quantum Chromodynamics at finite temperature and zero baryon chemical potential. We focus on the temperature range where the crossover from chirally broken phase to quark-gluon plasma takes place, namely $T \\simeq (150, 200)$ MeV. The processes we consider are quark-quark scatterings mediated by collective excitations with the quantum number of pions and $\\sigma$-meson, hence we refer to these processes simply as \\sugg{to} one-pion (one-$\\sigma$) exchange\\sugg{s}. We use a Nambu-Jona-Lasinio model to compute equilibrium properties of the thermal bath, as well as the relevant scattering kernel to be used in the collision integral to estimate the chiral relaxation time $\\tau$. We find $\\tau\\simeq 0.1 \\div 1$ fm/c around the chiral crossover.

  4. Consistent chiral kinetic theory in Weyl materials: chiral magnetic plasmons

    CERN Document Server

    Gorbar, E V; Shovkovy, I A; Sukhachov, P O

    2016-01-01

    We argue that the correct definition of the electric current in the chiral kinetic theory for Weyl materials should include the Chern--Simons contribution that makes the theory consistent with the local conservation of the electric charge in electromagnetic and strain-induced pseudoelectromagnetic fields. By making use of such a kinetic theory, we study the plasma frequencies of collective modes in Weyl materials in constant magnetic and pseudomagnetic fields taking into account the effects of dynamical electromagnetism. We show that the collective modes are chiral plasmons. While the plasma frequency of the longitudinal collective mode coincides with the Langmuir one, this mode is unusual because it is characterized not only by oscillations of the electric current density, but also oscillations of the chiral current density. The latter are triggered by a dynamical version of the chiral electric separation effect. We also find that the plasma frequencies of the transverse modes split up in a magnetic field. T...

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

    Energy Technology Data Exchange (ETDEWEB)

    Tartakovskaya, Elena V., E-mail: elena_tartakovskaya@yahoo.com [Institute of Magnetism NAS of Ukraine, Vernadsky blvd 36b, 03142 Kiev (Ukraine); Institute of High Technologies, Taras Shevchenko National University of Kiev, 03022 Kiev (Ukraine)

    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. - Highlights: • Field-induced spin chirality in magnetic multilayers is explained. • The roles of the RKKY, the DM and the Zeeman interactions are clarified. • Theoretical analysis of the chirality factor is in agreement with experimental data.

  6. Three chiral ionic liquids as additives for enantioseparation in capillary electrophoresis and their comparison with conventional modifiers.

    Science.gov (United States)

    Zhang, Qi; Qi, Xueyong; Feng, Chunlai; Tong, Shanshan; Rui, Mengjie

    2016-09-01

    The combined use of chiral ionic liquids (ILs) and conventional chiral selectors in CE to establish synergistic system has proven to be a convenient and effective approach for enantioseparation. In this work, three amino acid chiral ILs, tetramethylammonium-l-arginine (TMA-l-Arg), tetramethylammonium-l-hydroxyproline (TMA-l-Hyp) and tetramethylammonium-l-isoleucine (TMA-l-Ile), were first applied in CE enantioseparation to investigate their potential synergistic effect with hydroxypropyl-β-cyclodextrin (HP-β-CD). Markedly improved separations were obtained in the chiral ILs/HP-β-CD synergistic systems compared with single HP-β-CD system. Parameters, such as the chiral ILs concentration, HP-β-CD concentration, buffer pH, applied voltage and capillary temperature, were optimized. A systematic comparison of chiral ILs with conventional (commonly used) modifiers was also performed, including the use of achiral ILs, conventional salts and molecular organic solvents. In addition, the chiral configuration of ILs was investigated to demonstrate the existence of synergistic effect between chiral ILs and HP-β-CD. All these results indicate that chiral ILs, as additives for CE chiral separation, has significant superiority over conventional modifiers in certain cases. PMID:27515552

  7. Interlocked chiral/polar domain walls and large optical rotation in Ni3TeO6

    Directory of Open Access Journals (Sweden)

    Xueyun Wang

    2015-07-01

    Full Text Available Chirality, i.e., handedness, pervades much of modern science from elementary particles, DNA-based biology to molecular chemistry; however, most of the chirality-relevant materials have been based on complex molecules. Here, we report inorganic single-crystalline Ni3TeO6, forming in a corundum-related R3 structure with both chirality and polarity. These chiral Ni3TeO6 single crystals exhibit a large optical specific rotation (α—1355° dm−1 cm3 g−1. We demonstrate, for the first time, that in Ni3TeO6, chiral and polar domains form an intriguing domain pattern, resembling a radiation warning sign, which stems from interlocked chiral and polar domain walls through lowering of the wall energy.

  8. Interlocked chiral/polar domain walls and large optical rotation in Ni{sub 3}TeO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xueyun; Huang, Fei-Ting [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Yang, Junjie [Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Oh, Yoon Seok [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Cheong, Sang-Wook, E-mail: sangc@physics.rutgers.edu [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2015-07-01

    Chirality, i.e., handedness, pervades much of modern science from elementary particles, DNA-based biology to molecular chemistry; however, most of the chirality-relevant materials have been based on complex molecules. Here, we report inorganic single-crystalline Ni{sub 3}TeO{sub 6}, forming in a corundum-related R3 structure with both chirality and polarity. These chiral Ni{sub 3}TeO{sub 6} single crystals exhibit a large optical specific rotation (α)—1355° dm{sup −1} cm{sup 3} g{sup −1}. We demonstrate, for the first time, that in Ni{sub 3}TeO{sub 6}, chiral and polar domains form an intriguing domain pattern, resembling a radiation warning sign, which stems from interlocked chiral and polar domain walls through lowering of the wall energy.

  9. Chirality in photonic systems

    Science.gov (United States)

    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. xml:lang="fr"

  10. Reducible chiral metamaterials

    CERN Document Server

    Ciattoni, Alessandro; Rizza, Carlo

    2016-01-01

    We introduce the concept of 3D reducible metamaterials whose constituent permittivity can be modelled by a factorized profile. The separated cartesian coordinates dependence, easily achieved in all-optical reconfigurable materials, allows to physically regard a reducible metamaterial as a superposition of three fictitious 1D generating media. We prove that, in the long-wavelength limit, the electromagnetic response of reducible metamaterials can be reconstructed from the properties of the 1D generating media whose interplay provides large freedom to control the electromagnetic chirality. Our approach introduces an unprecedented decomposition strategy in metamaterial science which allows the full ab-initio and flexible design of a complex 3D bianisotropic response by using 1D metamaterials as basic building blocks.

  11. Chiral Dynamics With Wilson Fermions

    CERN Document Server

    Splittorff, K

    2012-01-01

    Close to the continuum the lattice spacing affects the smallest eigenvalues of the Wilson Dirac operator in a very specific manner determined by the way in which the discretization breaks chiral symmetry. These effects can be computed analytically by means of Wilson chiral perturbation theory and Wilson random matrix theory. A number of insights on chiral Dynamics with Wilson fermions can be obtained from the computation of the microscopic spectrum of the Wilson Dirac operator. For example, the unusual volume scaling of the smallest eigenvalues observed in lattice simulations has a natural explanation. The dynamics of the eigenvalues of the Wilson Dirac operator also allow us to determine the additional low energy constants of Wilson chiral perturbation theory and to understand why the Sharpe-Singleton scenario is only realized in unquenched simulations.

  12. Review of chiral perturbation theory

    Indian Academy of Sciences (India)

    B Ananthanarayan

    2003-11-01

    A review of chiral perturbation theory and recent developments on the comparison of its predictions with experiment is presented. Some interesting topics with scope for further elaboration are touched upon.

  13. Chiral Quark Model of Mesons

    CERN Document Server

    Wang, X J; Wang, Xiao-Jun; Yan, Mu-Lin

    1999-01-01

    We study SU(3)$_L\\timesSU(3)_R$ chiral quark model of mesons up to next leading order of $1/N_c$ expansion. Composite vector and axial-vector mesons resonances are introduced via non-linear realization of chiral SU(3) and vector meson dominant. Effects of one-loop graphs of pseudoscalar, vector and axial-vector mesons is calculated systematically and the significant results are obtained. Correction of effective gluon interaction is studied too. The light quark masses are introduced via new mechanism which agree with phenomenology and the requirement of chiral symmetry. Up to powers four of derivatives, chiral effective lagrangian of mesons is derived and evaluated to next leading order of $1/N_c$. Low energy limit of the model is examined. Ten low energy coupling constants $L_i(i=1,2,...,10)$ in ChPT are obtained and agree with ChPT well.

  14. Life's chirality from prebiotic environments

    Science.gov (United States)

    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.

  15. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Verné, Enrica, E-mail: enrica.verne@polito.it [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Bruno, Matteo [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Miola, Marta [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Maina, Giovanni; Bianco, Carlotta [Traumatology Orthopedics and Occupational Medicine Dept., Università di Torino, Via G. Zuretti 29, 10126 Torino (Italy); Cochis, Andrea [Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Rimondini, Lia [Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy)

    2015-08-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO{sub 2}–Na{sub 2}O–CaO–P{sub 2}O{sub 5}–FeO–Fe{sub 2}O{sub 3} and contains magnetite (Fe{sub 3}O{sub 4}) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite – HAp – layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. - Highlights: • An in vitro biological characterization was carried out on ferromagnetic and bioactive composite cements. • No release of iron was revealed in the physiological solution. • Bioactivity tests

  16. Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals.

    Science.gov (United States)

    Tortora, Luana; Lavrentovich, Oleg D

    2011-03-29

    In many colloidal systems, an orientationally ordered nematic (N) phase emerges from the isotropic (I) melt in the form of spindle-like birefringent tactoids. In cases studied so far, the tactoids always reveal a mirror-symmetric nonchiral structure, sometimes even when the building units are chiral. We report on chiral symmetry breaking in the nematic tactoids formed in molecularly nonchiral polymer-crowded aqueous solutions of low-molecular weight disodium cromoglycate. The parity is broken by twisted packing of self-assembled molecular aggregates within the tactoids as manifested by the observed optical activity. Fluorescent confocal microscopy reveals that the chiral N tactoids are located at the boundaries of cells. We explain the chirality induction as a replacement of energetically costly splay packing of the aggregates within the curved bipolar tactoidal shape with twisted packing. The effect represents a simple pathway of macroscopic chirality induction in an organic system with no molecular chirality, as the only requirements are orientational order and curved shape of confinement.

  17. Homogenization of resonant chiral metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Menzel, C.; Rockstuhl, Carsten;

    2010-01-01

    Homogenization of metamaterials is a crucial issue as it allows to describe their optical response in terms of effective wave parameters as, e.g., propagation constants. In this paper we consider the possible homogenization of chiral metamaterials. We show that for meta-atoms of a certain size...... an analytical criterion for performing the homogenization and a tool to predict the homogenization limit. We show that strong coupling between meta-atoms of chiral metamaterials may prevent their homogenization at all....

  18. Chiral thermodynamics of nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Fiorilla, Salvatore

    2012-10-23

    The equation of state of nuclear matter is calculated at finite temperature in the framework of in-medium chiral perturbation theory up to three-loop order. The dependence of its thermodynamic properties on the isospin-asymmetry is investigated. The chiral quark condensate is evaluated for symmetric nuclear matter. Its behaviour as a function of density and temperature sets important nuclear physics constraints for the QCD phase diagram.

  19. Chiral symmetry and lattice fermions

    CERN Document Server

    Creutz, Michael

    2013-01-01

    Lattice gauge theory and chiral perturbation theory are among the primary tools for understanding non-perturbative aspects of QCD. I review several subtle and sometimes controversial issues that arise when combining these techniques. Among these are one failure of partially quenched chiral perturbation theory when the valence quarks become lighter than the average sea quark mass and a potential ambiguity in comparisons of perturbative and lattice properties of non-degenerate quarks.

  20. Modulated nematic structures induced by chirality and steric polarization

    Science.gov (United States)

    Longa, Lech; PajÄ k, Grzegorz

    2016-04-01

    What kind of one-dimensional modulated nematic structures (ODMNS) can form nonchiral and chiral bent-core and dimeric materials? Here, using the Landau-de Gennes theory of nematics, extended to account for molecular steric polarization, we study a possibility of formation of ODMNS, both in nonchiral and intrinsically chiral liquid crystalline materials. Besides nematic and cholesteric phases, we find four bulk ODMNS for nonchiral materials, two of which, to the best of our knowledge, have not been reported so far. These two structures are longitudinal (NLP) and transverse (NTP) periodic waves where the polarization field being periodic in one dimension stays parallel and perpendicular, respectively, to the wave vector. The other two phases are the twist-bend nematic phase (NTB) and the splay-bend nematic phase (NSB), but their fine structure appears more complex than that considered so far. The presence of molecular chirality converts nonchiral NTP and NSB into new NTB phases. Surprisingly, the nonchiral NLP phase can stay stable even in the presence of intrinsic chirality.

  1. Analytical solutions for elastic binary nanotubes of arbitrary chirality

    Science.gov (United States)

    Jiang, Lai; Guo, Wanlin

    2016-09-01

    Analytical solutions for the elastic properties of a variety of binary nanotubes with arbitrary chirality are obtained through the study of systematic molecular mechanics. This molecular mechanics model is first extended to chiral binary nanotubes by introducing an additional out-of-plane inversion term into the so-called stick-spiral model, which results from the polar bonds and the buckling of binary graphitic crystals. The closed-form expressions for the longitudinal and circumferential Young's modulus and Poisson's ratio of chiral binary nanotubes are derived as functions of the tube diameter. The obtained inversion force constants are negative for all types of binary nanotubes, and the predicted tube stiffness is lower than that by the former stick-spiral model without consideration of the inversion term, reflecting the softening effect of the buckling on the elastic properties of binary nanotubes. The obtained properties are shown to be comparable to available density functional theory calculated results and to be chirality and size sensitive. The developed model and explicit solutions provide a systematic understanding of the mechanical performance of binary nanotubes consisting of III-V and II-VI group elements.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  4. Chirality in Bare and Passivated Gold Nanoclusters

    CERN Document Server

    Garzon, I L; Rodrigues-Hernandez, J I; Sigal, I; Beltran, M R; Michaelian, K

    2002-01-01

    Chiral structures have been found as the lowest-energy isomers of bare (Au$_{28}$ and Au$_{55}) and thiol-passivated (Au$_{28}(SCH$_{3})$_{16}$ and Au$_{38}$(SCH$_{3}$)$_{24}) gold nanoclusters. The degree of chirality existing in the chiral clusters was calculated using the Hausdorff chirality measure. We found that the index of chirality is higher in the passivated clusters and decreases with the cluster size. These results are consistent with the observed chiroptical activity recently reported for glutahione-passivated gold nanoclusters, and provide theoretical support for the existence of chirality in these novel compounds.

  5. Ferrimagnetic ceramic adsorbents for cleanup of H2S from exhaust gases

    Institute of Scientific and Technical Information of China (English)

    Bernd; Halbedel; Apostolos; Kontogeorgakos

    2007-01-01

    Adsorbents that exhibit magnetic properties in addition to other required process-relevant characteristics open up new perspectives for the dry reduction and/or elimination of H2S and other sulfur compounds from exhaust gases. These adsorbents eliminate the sulfur compounds from exhaust gases by virtue of their coatings and their magnetic property which makes it possible the use of magnetically assisted and stabilized fluidization in an externally applied magnetic field.In the present paper, the feasibility of the sorptive function of porous ceramic ferrimagnetic beads is ensured by sol-gel coating of zinc oxide without the formation of Zn-Fe-oxides and without considerable decrease of available pore volume. The results of material characterization by SEM, Auger electron spectroscopy, X-ray and mercury-porosity measurements and the loading capacity of a H2S/N2 model gas are presented and discussed. The resulting H2S loading of the functionalized adsorbent beads is more than 10 times larger than that of the starting material.

  6. Evidence for ferromagnetic coupling at the doped topological insulator/ferrimagnetic insulator interface

    Science.gov (United States)

    Liu, Wenqing; He, Liang; Zhou, Yan; Murata, Koichi; Onbasli, Mehmet C.; Ross, Caroline A.; Jiang, Ying; Wang, Yong; Xu, Yongbing; Zhang, Rong; Wang, Kang. L.

    2016-05-01

    One of the major obstacles of the magnetic topological insulators (TIs) impeding their practical use is the low Curie temperature (Tc). Very recently, we have demonstrated the enhancement of the magnetic ordering in Cr-doped Bi2Se3 by means of proximity to the high-Tc ferrimagnetic insulator (FMI) Y3Fe5O12 and found a large and rapidly decreasing penetration depth of the proximity effect, suggestive of a different carrier propagation process near the TI surface. Here we further present a study of the interfacial magnetic interaction of this TI/FMI heterostrucutre. The synchrotron-based X-ray magnetic circular dichroism (XMCD) technique was used to probe the nature of the exchange coupling of the Bi2-xCrxSe3/Y3Fe5O12 interface. We found that the Bi2-xCrxSe3 grown on Y3Fe5O12(111) predominately contains Cr3+ cations, and the spin direction of the Cr3+ is aligned parallel to that of tetrahedral Fe3+ of the YIG, revealing a ferromagnetic exchange coupling between the Bi2-xCrxSe3 and the Y3Fe5O12.

  7. Evidence of ferrimagnetic ordering in FeMnO{sub 3} produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Seifu, D. E-mail: dseifu@morgan.edu; Kebede, A.; Oliver, F.W.; Hoffman, E.; Hammond, E.; Wynter, C.; Aning, A.; Takacs, L.; Siu, I.-L.; Walker, J.C.; Tessema, G.; Seehra, M.S

    2000-03-01

    Mechanical alloying of {alpha}-Fe{sub 2}O{sub 3} with Mn{sub 2}O{sub 3} is shown to produce FeMnO{sub 3}, whose X-ray diffraction pattern fits the cubic structure (space group Ia3, lattice constant {approx}9.40 A) identical to that of Mn{sub 2}O{sub 3}. Temperature variation of its magnetic susceptibility {chi} shows a phase transition near T{sub c}{approx}40 K and the {chi}{sup -1} versus T data for T>T{sub c} fit the variation expected for a ferrimagnet with a magnetic moment of 2.8 {mu}{sub B} per formula unit. The Moessbauer spectrum for T>T{sub c} is a doublet with quadrupole splitting {approx}1 mm/s and isomer shift {approx}0.4 mm/s, changing to a sextet for T

  8. A New Method For The Separation Of Weak Antiferromagnetic Signal From A Strong Ferrimagnetic Background

    Science.gov (United States)

    Liu, Q.; Subir, B. K.; Jackson, M.; Zhu, R.; Pan, Y.

    2001-12-01

    A new parameter Mfr (the final remanence after a slow hysteretic demagnetization process) for the detection of the concentration of weak antiferromagnetic (AFM) minerals against a strong ferrimagnetic (FM) background is put forward by taking advantage of their sharply different H0 (the critical maximum field that can decrease Mfr to zero) values. For strong FM minerals (magnetite, maghemite), H0 values are less than 0.3 T, while for antiferromagnetic materials (such as hematite) with weak magnetic remanence, H0 is larger than 1 T. With synthetic samples, experiments showed that Mfr has a higher sensitivity to detect AFM minerals than the HIRM method because it has a higher random error caused by the required subtraction of two numbers. The latter requires measurements in the presence of high applied-fields (generally 0.3 to 1T). Mfr, on the other hand, being a remanence, is measured at zero applied fields. Detailed Mfr data for YiChuan (Gansu province, China) loess samples indicate that paleosol unit S1contains a higher concentration of FM but lower concentration of AFM minerals compared to that of the loess units above and below. This suggests the formation of Fe2+ bearing minerals at the cost of Fe3+ bearing AFM minerals during pedogenesis.

  9. Strain controlled ferromagnetic-ferrimagnetic transition and vacancy formation energy of defective graphene

    Science.gov (United States)

    Zhang, Yajun; Sahoo, MPK; Wang, Jie

    2016-10-01

    Single vacancy (SV)-induced magnetism in graphene has attracted much attention motivated by its potential in achieving new functionalities. However, a much higher vacancy formation energy limits its direct application in electronic devices and the dependency of spin interaction on the strain is unclear. Here, through first-principles density-functional theory calculations, we investigate the possibility of strain engineering towards lowering vacancy formation energy and inducing new magnetic states in defective graphene. It is found that the SV-graphene undergoes a phase transition from an initial ferromagnetic state to a ferrimagnetic state under a biaxial tensile strain. At the same time, the biaxial tensile strain significantly lowers the vacancy formation energy. The charge density, density of states and band theory successfully identify the origin and underlying physics of the transition. The predicted magnetic phase transition is attributed to the strain driven spin flipping at the C-atoms nearest to the SV-site. The magnetic semiconducting graphene induced by defect and strain engineering suggests an effective way to modulate both spin and electronic degrees of freedom in future spintronic devices.

  10. Current driven magnetization dynamics of a self-polarised synthetic ferrimagnet

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, A. S.; Lacoste, B.; Geranton, G.; Gusakova, D.; Dieny, B.; Ebels, U.; Buda-Prejbeanu, L. D. [SPINTEC, UMR-8191, CNRS/CEA-INAC/UJF-Grenoble, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)

    2014-02-28

    Spin torque driven excitations in spin valves and tunnel junctions are often investigated for a two magnetic layer system for which a polarizer (fixed magnetization) and a free layer can be distinguished. In the search for improved microwave properties and to understand the role of different coupling mechanisms between the magnetic layers, here, the excitation spectrum of an exchange coupled two layer synthetic ferrimagnet (SyF) system is investigated numerically with spin momentum transfer acting on both layers simultaneously. This self-polarised two layer system does not contain an external polarizer, and excitation of coupled modes arises due to the mutual spin transfer torque and the Ruderman-Kittel-Kasuya-Yosida interlayer exchange coupling. The current-field state diagrams of static and dynamic states are reported as a function of the interlayer exchange coupling strength. The numerically determined critical boundaries are well reproduced by an analytical stability analysis. The dynamic steady states reveal an optic-like mode at low magnetic fields, which becomes progressively acoustic-like for increased magnetic fields and currents. The frequency of these modes can be tuned by the film thickness and the strength of the interlayer exchange interaction. The results presented here will provide an important guide for designing spin torque oscillators that exploit the dynamic coupling between layers and, furthermore, they will provide a basis to test analytical models of spin torque driven coupled excitations.

  11. New ferrimagnetic biocomposite film based in collagen and yttrium iron garnet

    Directory of Open Access Journals (Sweden)

    2010-12-01

    Full Text Available In recent years a great interest in the study of the association of magnetic with biological material for bioapplications has been observed in the literature. This work analyses the development of new magnetic biocomposite films from a magnetic ferrite and a biopolymer. Magnetic and dielectric properties of Y3Fe5O12 (YIG/collagen composite films were studied as a function of the YIG concentration. This biocomposite was also characterized by Infrared Spectroscopy (IR, Thermal Analysis (DSC and TG and scanning electron microspcopic (SEM methods. The magnetization and dielectric measurements were performed at room temperature. The results demonstrated that ferrimagnetic garnet (YIG and collagen (Col can be used to obtain a homogeneous composite. All the composite films showed a ferromagnetic behavior and they were characterized as a soft magnet material. These results show that Col-YIG biocomposites are biological films with magnetic properties that can be employed as a versatile performance materials, due to their flexible dielectric and magnetic features. They could be used as electronic devices in biological applications.

  12. Comparison of the irreversible thermomagnetic behaviour of some ferro- and ferrimagnetic systems

    Indian Academy of Sciences (India)

    P S Anil Kumar; P A Joy; S K Date

    2000-04-01

    The magnetic behaviour of two ferromagnetic oxides and two ferrimagnetic oxides (ferrites) are compared to study the effect of magnetocrystalline anisotropy on thermal-history-dependence of magnetization of these ordered magnetic systems. All four compounds show thermomagnetic irreversibility (FC > ZFC) below a certain temperature, irr. The highly anisotropic ferromagnetic oxide, SrRuO3 and the hard ferrite, SrFe12O19 show sharp peaks below in their ZFC() curves, whereas for the soft ferrite Ni0.8Zn0.2Fe2O4 and the low anisotropic ferromagnetic oxide La0.7Ca0.3MnO3 only a broad maximum is observed in ZFC, when measured in small magnetic fields. The shapes of the ZFC() curves are inversely-related to the magnitude of the coercivities (c) of the compounds in relation to the applied field, and the temperature dependence of (c). FCand ZFC are related through the coercivity for all four magnetic systems.

  13. Using the Chiral Organophosphorus Derivatizing Agents for Determination of the Enantiomeric Composition of Chiral Carboxylic Acids by 31PNMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Chao CHE; Zhong Ning ZHANG; Gui Lan HUANG; Xin Xing WANG; Zhao Hai QIN

    2004-01-01

    The use of chiral organophosphorus derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.

  14. Bottom-up graphene-nanoribbon fabrication reveals chiral edges and enantioselectivity.

    Science.gov (United States)

    Han, Patrick; Akagi, Kazuto; Federici Canova, Filippo; Mutoh, Hirotaka; Shiraki, Susumu; Iwaya, Katsuya; Weiss, Paul S; Asao, Naoki; Hitosugi, Taro

    2014-09-23

    We produce precise chiral-edge graphene nanoribbons on Cu{111} using self-assembly and surface-directed chemical reactions. We show that, using specific properties of the substrate, we can change the edge conformation of the nanoribbons, segregate their adsorption chiralities, and restrict their growth directions at low surface coverage. By elucidating the molecular-assembly mechanism, we demonstrate that our method constitutes an alternative bottom-up strategy toward synthesizing defect-free zigzag-edge graphene nanoribbons.

  15. Electrical Property Analytical Prediction on Archimedes Chiral Carbon Nanoscrolls

    Science.gov (United States)

    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.

  16. Electrical Property Analytical Prediction on Archimedes Chiral Carbon Nanoscrolls

    Science.gov (United States)

    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.

  17. Chiral symmetry in rotating systems

    Science.gov (United States)

    Malik, Sham S.

    2015-08-01

    The triaxial rotating system at critical angular momentum I ≥Iband exhibits two enatiomeric (the left- and right-handed) forms. These enatiomers are related to each other through dynamical chiral symmetry. The chiral symmetry in rotating system is defined by an operator χ ˆ =Rˆy (π) T ˆ, which involves the product of two distinct symmetries, namely, continuous and discrete. Therefore, new guidelines are required for testing its commutation with the system Hamiltonian. One of the primary objectives of this study is to lay down these guidelines. Further, the possible impact of chiral symmetry on the geometrical arrangement of angular momentum vectors and investigation of observables unique to nuclear chiral-twins is carried out. In our model, the angular momentum components (J1, J2, J3) occupy three mutually perpendicular axes of triaxial shape and represent a non-planar configuration. At certain threshold energy, the equation of motion in angular momentum develops a second order phase transition and as a result two distinct frames (i.e., the left- and right-handed) are formed. These left- and right-handed states correspond to a double well system and are related to each other through chiral operator. At this critical angular momentum, the centrifugal and Coriolis interactions lower the barrier in the double well system. The tunneling through the double well starts, which subsequently lifts the degeneracy among the rotational states. A detailed analysis of the behavior of rotational energies, spin-staggering, and the electromagnetic transition probabilities of the resulting twin-rotational bands is presented. The ensuing model results exhibit similarities with many observed features of the chiral-twins. An advantage of our formalism is that it is quite simple and it allows us to pinpoint the understanding of physical phenomenon which lead to chiral-twins in rotating systems.

  18. Surface second harmonic generation of chiral molecules using three-coupled-oscillator model

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Ou; Li Chun-Fei; Li Jun-Qing

    2006-01-01

    Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic parameters on the second-order susceptibilities is simulated numerically and the difference between the efficiencies of s-polarized second-harmonic fields induced by the left- and the right-handed circularly-polarized fundamental beams is discussed. The theoretical basis for studying second-order nonlinear optical properties of the chiral molecular media with a tripod-like structure is provided in this paper.

  19. Chiral Thirring–Wess model

    Energy Technology Data Exchange (ETDEWEB)

    Rahaman, Anisur, E-mail: anisur.rahman@saha.ac.in

    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.

  20. Tactoids of chiral liquid crystals

    Science.gov (United States)

    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.

  1. Chiral gap effect in curved space

    CERN Document Server

    Flachi, Antonino

    2014-01-01

    We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum a mass gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.

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

    Science.gov (United States)

    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.

  3. Chiral dynamics of baryons in the perturbative chiral quark model

    Energy Technology Data Exchange (ETDEWEB)

    Pumsa-ard, K.

    2006-07-01

    In this work we develop and apply variants of a perturbative chiral quark model (PCQM) to the study of baryonic properties dominantly in the low-energy region. In a first step we consider a noncovariant form of the PCQM, where confinement is modelled by a static, effective potential and chiral corrections are treated to second order, in line with similar chiral quark models. We apply the PCQM to the study of the electromagnetic form factors of the baryon octet. We focus in particular on the low-energy observables such as the magnetic moments, the charge and magnetic radii. In addition, the electromagnetic N-delta transition is also studied in the framework of the PCQM. In the chiral loop calculations we consider a quark propagator, which is restricted to the quark ground state, or in hadronic language to nucleon and delta intermediate states, for simplicity. We furthermore include the low-lying excited states to the quark propagator. In particular, the charge radius of the neutron and the transverse helicity amplitudes of the N-delta transition are considerably improved by this additional effect. In a next step we develop a manifestly Lorentz covariant version of the PCQM, where in addition higher order chiral corrections are included. The full chiral quark Lagrangian is motivated by and in analogy to the one of Chiral Perturbation Theory (ChPT). This Lagrangian contains a set of low energy constants (LECs), which are parameters encoding short distance effects and heavy degrees of freedom. We evaluate the chiral Lagrangian to order O(p{sup 4}) and to one loop to generate the dressing of the bare quark operators by pseudoscalar mesons. In addition we include the vector meson degrees of freedom in our study. Projection of the dressed quark operators on the baryonic level serves to calculate the relevant matrix elements. In a first application of this scheme, we resort to a parameterization of the valence quark form factors in the electromagnetic sector. Constraints

  4. Absolute Asymmetric Synthesis: The Origin, Control, and Amplification of Chirality

    OpenAIRE

    Delden, Richard A. van; Feringa, Bernard

    1999-01-01

    One of the fundamental and intriguing aspects of life is the homochirality of the essential molecules. From the early days of stereochemistry, the origin of chirality in biological systems has been a challenge to the chemical sciences and numerous theories and experiments have been reported. Despite the great progress in asymmetric synthesis, there are only a few genuine absolute asymmetric syntheses known today. Novel approaches based on the interplay of molecular biology, organic chemistry,...

  5. Quenched Chiral Perturbation Theory to one loop

    NARCIS (Netherlands)

    Colangelo, G.; Pallante, E.

    1998-01-01

    The divergences of the generating functional of quenched Chiral Perturbation theory (qCHPT) to one loop are computed in closed form. We show how the quenched chiral logarithms can be reabsorbed in the renormalization of the B0 parameter of the leading order Lagrangian. Finally, we do the chiral powe

  6. Neutrino Oscillation Induced by Chiral Phase Transition

    Institute of Scientific and Technical Information of China (English)

    MU Cheng-Fu; SUN Gao-Feng; ZHUANG Peng-Fei

    2009-01-01

    Electric charge neutrality provides a relationship between chiral dynamics and neutrino propagation in compact stars.Due to the sudden drop of the electron density at the first-order chiral phase transition,the oscillation for low energy neutrinos is significant and can be regarded as a signature of chiral symmetry restoration in the core of compact stars.

  7. Shear Viscosity of Turbulent Chiral Plasma

    CERN Document Server

    Kumar, Avdhesh; Das, Amita; Kaw, P K

    2016-01-01

    It is well known that the difference between the chemical potentials of left-handed and right-handed particles in a parity violating (chiral) plasma can lead to an instability. We show that the chiral instability may drive turbulent transport. Further we estimate the anomalous viscosity of chiral plasma arising from the enhanced collisionality due to turbulence.

  8. Solutions of ward's modified chiral model

    International Nuclear Information System (INIS)

    We discuss the adaptation of Uhlenbeck's method of solving the chiral model in 2 Euclidean dimensions to Ward's modified chiral model in (2+1) dimensions. We show that the method reduces the problem of solving the second-order partial differential equations for the chiral field to solving a sequence of first-order partial differential equations for time dependent projector valued fields

  9. Chiral cardiovascular drugs: an overview.

    Science.gov (United States)

    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.

  10. Synthetic Applications of Chiral Furanboronate

    Institute of Scientific and Technical Information of China (English)

    CHAN; KinFai

    2001-01-01

    We recently uncovered that consecutive reactions of chiral furfural-boronate 1 with a lithium alkoxide and a nucleophile led to the formation of alcohols 2 with good diastereoselection in favor of S-configuration at the newly generated chiral carbon. In addition, it was also found that 2a and 2b were chromatographically separable on a silica gel column. This reaction is believed to involve a tetrahedral borate intermediate, as can be substantiated by 11BNMR spectroscopic studies. Chiral furanmethanolboronates 2a(or 2b) underwent a palladium-catalyzed Suzuki coupling to form enantiomerically pure furans 3, which can be further converted to the synthetically useful hydroxypyranones 4.1,2,3 In addition, Mukaiyama reaction of 1 also led to chromatographically separable diastereomeric aldol-products. The scope and limitation of these conversions will be discussed.  ……

  11. Chiral interaction and biomolecular evolution

    International Nuclear Information System (INIS)

    Recent developments in the concept of chiral interaction open now new options and dynamical possibilities for biomolecules which have so far been overlooked. A few of these possibilities are mentioned, such as the control mechanism of enzymatic activity and the role played by non-ergodicity in evolutionary processes. It is shown that chiral interaction, being a surface phenomenon, does not obey Barron's symmetry constraints, which are suitable for force fields present in bulk interactions. In particular, the situation at the ocean-air surface in the prebiotic era is described, as well as the possible role played by chiral interaction in conjunction with the terrestrial magnetic field normal to the ocean surface, which could have lead to a process of deracernization at the ocean-air interface. (author)

  12. Competition of the Peierls relief and structural defects in damping the domain walls in [Mn left brace (R/S)-pn right brace]2[Mn left brace(R/S)-pn right brace2(H2O)][Cr(CN)6]2 ferrimagnet

    International Nuclear Information System (INIS)

    The [ [Mn left brace (R/S)-pn right brace]2[Mn left brace(R/S)-pn right brace2(H2O)][Cr(CN)6]2 molecular ferrimagnet exhibits an inverse sequence of changes in the domain wall motion regimes with increasing temperature in alternative magnetic field of 0.04-1400 Hz frequency. Initiation of the relaxation regime on the background of creep indicates that there are two different systems of the domain walls damping. The threshold amplitude of the alternative magnetic field corresponds to the Peierls relief contribution to the domain wall dynamics as well as the defect contribution usually considered.

  13. SYNTHESIS OF CHIRAL CONJUGATED POLYBINAPHTHYLS BY SONOGASHIRA REACTION

    Institute of Scientific and Technical Information of China (English)

    Yi-xiang Cheng; Ling-wu Chen; Xiao-wei Zou; Jin-feng Song

    2006-01-01

    Chiral polymers P-1 and P-2 were synthesized by the polymerization of (R)-3,3'-diiodo-2,2'-bisbutoxy-1,l'-binaphthyl (M-1) with 2,5-di(4-ethynylphenyl)-1,3,4-oxadiazole (M-3) and (R)-3,3'-diethylnyl-2,2'-bisbutoxy-1,1'-binaphthyl (M-2) with 1,2-di(4-bromophenyl)acetylene (M-4) under Sonogashira reaction, respectively. Both monomers and polymers were analyzed by NMR, MS, FT-IR, UV-Vis spectroscopy, DSC-TGA, fluorescence spectroscopy, GPC and CD spectroscopy. CD spectra of P-1 and P-2 are similar due to the same chiral center units and main chain structure. The long wavelengths CD effect of P-1 and P-2 can be regarded as the more extended conjugated structure and a highly rigid backbone in the polymer chain. Polymers have strong blue fluorescence due to the efficient energy migration from the extended π-electronic structure of the polymers to the chiral binaphthyl core and are expected to provide understanding of the relationship between molecular structure and fluorescent property of the chiral polymers.

  14. Chiral Colloidal Molecules And Observation of The Propeller Effect

    Science.gov (United States)

    2013-01-01

    Chiral molecules play an important role in biological and chemical processes, but physical effects due to their symmetry-breaking are generally weak. Several physical chiral separation schemes which could potentially be useful, including the propeller effect, have therefore not yet been demonstrated at the molecular scale. However, it has been proposed that complex nonspherical colloidal particles could act as “colloidal molecules” in mesoscopic model systems to permit the visualization of molecular phenomena that are otherwise difficult to observe. Unfortunately, it is difficult to synthesize such colloids because surface minimization generally favors the growth of symmetric particles. Here we demonstrate the production of large numbers of complex colloids with glancing angle physical vapor deposition. We use chiral colloids to demonstrate the Baranova and Zel’dovich (BaranovaN. B.Zel’dovichB. Y.Chem. Phys. Lett.1978, 57, 435) propeller effect: the separation of a racemic mixture by application of a rotating field that couples to the dipole moment of the enantiomers and screw propels them in opposite directions. The handedness of the colloidal suspensions is monitored with circular differential light scattering. An exact solution for the colloid’s propulsion is derived, and comparisons between the colloidal system and the corresponding effect at the molecular scale are made. PMID:23883328

  15. Chiral symmetry on the lattice

    International Nuclear Information System (INIS)

    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

  16. Asymmetric Synthesis via Chiral Aziridines

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Harden, Adrian; Wyatt, Paul;

    1996-01-01

    A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines)]. In the b......A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines...

  17. Novel Chiral Auxiliaries of BIAZOLs

    Institute of Scientific and Technical Information of China (English)

    CHEN; Arh-Hwang

    2001-01-01

    Asymmetric catalysis is one of the most challenging and formidable endeavor in organic synthesis. The development of chiral auxiliaries is a key in the asymmetric catalysis. Azulenoids, a parent structure of bicyclo[5.3.0]decapentaene with 10 πelectrons, are useful as dye materials, medical treatment of inflammation and hypertension, and the development of liquid crystals. In continuing to investigate synthetic application of azulenoids, we have studied to develop novel chiral auxiliaries of BIAZOLs. The BIAZOLs were synthesized from dicyclopentadiene and characterized using spectroscopies.  ……

  18. Novel Chiral Auxiliaries of BIAZOLs

    Institute of Scientific and Technical Information of China (English)

    CHEN Arh-Hwang; YUAN Shou-Bin; CHIU Shu-Ching

    2001-01-01

    @@ Asymmetric catalysis is one of the most challenging and formidable endeavor in organic synthesis. The development of chiral auxiliaries is a key in the asymmetric catalysis. Azulenoids, a parent structure of bicyclo[5.3.0]decapentaene with 10 πelectrons, are useful as dye materials, medical treatment of inflammation and hypertension, and the development of liquid crystals. In continuing to investigate synthetic application of azulenoids, we have studied to develop novel chiral auxiliaries of BIAZOLs. The BIAZOLs were synthesized from dicyclopentadiene and characterized using spectroscopies.

  19. Chiral Baryon with Quantized Pions

    CERN Document Server

    McNeil, J A

    1993-01-01

    We study a hybrid chiral model for the nucleon based on the linear sigma model with explicit quarks. We solve the model using a Fock-space configuration consisting of three quarks plus three quarks and a pion as the ground state ansatz in place of the ``hedgehog'' ansatz. We minimize the expectation value of the chiral hamiltonian in this ground state configuration and solve the resulting equations for nucleon quantum numbers. We calculate the canonical set of nucleon observables and compare with previous work.

  20. Strange chiral nucleon form factors

    CERN Document Server

    Hemmert, T R; Meißner, Ulf G; Hemmert, Thomas R.; Kubis, Bastian; Meissner, Ulf-G.

    1999-01-01

    We investigate the strange electric and magnetic form factors of the nucleon in the framework of heavy baryon chiral perturbation theory to third order in the chiral expansion. All counterterms can be fixed from data. In particular, the two unknown singlet couplings can be deduced from the parity-violating electron scattering experiments performed by the SAMPLE and the HAPPEX collaborations. Within the given uncertainties, our analysis leads to a small and positive electric strangeness radius, $ = (0.05 \\pm 0.16) fm^2$. We also deduce the consequences for the upcoming MAMI A4 experiment.

  1. Asymmetric Synthesis of Fluoroamines from Chiral Aziridines

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyeonjeong; Yoon, Dooha; Ha, Hyunjoon [Hankuk Univ. of Foreign Studies, Yongin (Korea, Republic of); Son, Se In; Lee, Won Koo [Sogang Univ., Seoul (Korea, Republic of)

    2014-03-15

    We described an efficient preparation of fluoroamines by the ring-opening reactions of chiral aziridines with Et{sub 3}N·3HF. At most cases both regioisomers were obtained from the ring openings at C2 and C3 positions depending on the substituents at C2 of the starting substrates.The fluorinated organic molecules have attracted great attentions from synthetic and medicinal chemists with wide use of various agrochemicals and pharmaceuticals. Their uniqueness is originated from its electronic characteristics and the small size without altering the molecular conformations of non-fluorinated compounds. The fluorine is the second most widely used atom in the commercial drugs following the amine. Thereby, the elaboration of fluoro-amines bearing two most widely used atoms in drugs is one of the most challenging problems in drug synthesis and its development.

  2. Multicomponent, peptide-targeted glycol chitosan nanoparticles containing ferrimagnetic iron oxide nanocubes for bladder cancer multimodal imaging.

    Science.gov (United States)

    Key, Jaehong; Dhawan, Deepika; Cooper, Christy L; Knapp, Deborah W; Kim, Kwangmeyung; Kwon, Ick Chan; Choi, Kuiwon; Park, Kinam; Decuzzi, Paolo; Leary, James F

    2016-01-01

    While current imaging modalities, such as magnetic resonance imaging (MRI), computed tomography, and positron emission tomography, play an important role in detecting tumors in the body, no single-modality imaging possesses all the functions needed for a complete diagnostic imaging, such as spatial resolution, signal sensitivity, and tissue penetration depth. For this reason, multimodal imaging strategies have become promising tools for advanced biomedical research and cancer diagnostics and therapeutics. In designing multimodal nanoparticles, the physicochemical properties of the nanoparticles should be engineered so that they successfully accumulate at the tumor site and minimize nonspecific uptake by other organs. Finely altering the nano-scale properties can dramatically change the biodistribution and tumor accumulation of nanoparticles in the body. In this study, we engineered multimodal nanoparticles for both MRI, by using ferrimagnetic nanocubes (NCs), and near infrared fluorescence imaging, by using cyanine 5.5 fluorescence molecules. We changed the physicochemical properties of glycol chitosan nanoparticles by conjugating bladder cancer-targeting peptides and loading many ferrimagnetic iron oxide NCs per glycol chitosan nanoparticle to improve MRI contrast. The 22 nm ferrimagnetic NCs were stabilized in physiological conditions by encapsulating them within modified chitosan nanoparticles. The multimodal nanoparticles were compared with in vivo MRI and near infrared fluorescent systems. We demonstrated significant and important changes in the biodistribution and tumor accumulation of nanoparticles with different physicochemical properties. Finally, we demonstrated that multimodal nanoparticles specifically visualize small tumors and show minimal accumulation in other organs. This work reveals the importance of finely modulating physicochemical properties in designing multimodal nanoparticles for bladder cancer imaging. PMID:27621615

  3. Multicomponent, peptide-targeted glycol chitosan nanoparticles containing ferrimagnetic iron oxide nanocubes for bladder cancer multimodal imaging

    Science.gov (United States)

    Key, Jaehong; Dhawan, Deepika; Cooper, Christy L; Knapp, Deborah W; Kim, Kwangmeyung; Kwon, Ick Chan; Choi, Kuiwon; Park, Kinam; Decuzzi, Paolo; Leary, James F

    2016-01-01

    While current imaging modalities, such as magnetic resonance imaging (MRI), computed tomography, and positron emission tomography, play an important role in detecting tumors in the body, no single-modality imaging possesses all the functions needed for a complete diagnostic imaging, such as spatial resolution, signal sensitivity, and tissue penetration depth. For this reason, multimodal imaging strategies have become promising tools for advanced biomedical research and cancer diagnostics and therapeutics. In designing multimodal nanoparticles, the physicochemical properties of the nanoparticles should be engineered so that they successfully accumulate at the tumor site and minimize nonspecific uptake by other organs. Finely altering the nano-scale properties can dramatically change the biodistribution and tumor accumulation of nanoparticles in the body. In this study, we engineered multimodal nanoparticles for both MRI, by using ferrimagnetic nanocubes (NCs), and near infrared fluorescence imaging, by using cyanine 5.5 fluorescence molecules. We changed the physicochemical properties of glycol chitosan nanoparticles by conjugating bladder cancer-targeting peptides and loading many ferrimagnetic iron oxide NCs per glycol chitosan nanoparticle to improve MRI contrast. The 22 nm ferrimagnetic NCs were stabilized in physiological conditions by encapsulating them within modified chitosan nanoparticles. The multimodal nanoparticles were compared with in vivo MRI and near infrared fluorescent systems. We demonstrated significant and important changes in the biodistribution and tumor accumulation of nanoparticles with different physicochemical properties. Finally, we demonstrated that multimodal nanoparticles specifically visualize small tumors and show minimal accumulation in other organs. This work reveals the importance of finely modulating physicochemical properties in designing multimodal nanoparticles for bladder cancer imaging. PMID:27621615

  4. Scaling laws in chiral hydrodynamic turbulence

    CERN Document Server

    Yamamoto, Naoki

    2016-01-01

    We study the turbulent regime of chiral (magneto)hydrodynamics for charged and neutral matter with chirality imbalance. We find that the chiral magnetohydrodynamics for charged plasmas possesses a unique scaling symmetry only without fluid helicity under the local charge neutrality. We also find a different type of unique scaling symmetry in the chiral hydrodynamics for neutral matter with fluid helicity in the inertial range. We show that these symmetries dictate the self-similar inverse cascade of the magnetic and kinetic energies. Our results imply the possible inverse energy cascade in core-collapse supernovae due to the chiral transport of neutrinos.

  5. Chiral magnetic effect in the PNJL model

    CERN Document Server

    Fukushima, Kenji; Gatto, Raoul

    2010-01-01

    We study the two-flavor Nambu--Jona-Lasinio model with the Polyakov loop (PNJL model) in the presence of a strong magnetic field and a chiral chemical potential $\\mu_5$ which mimics the effect of imbalanced chirality due to QCD instanton and/or sphaleron transitions. Firstly we focus on the properties of chiral symmetry breaking and deconfinement crossover under the strong magnetic field. Then we discuss the role of $\\mu_5$ on the phase structure. Finally the chirality charge, electric current, and their susceptibility, which are relevant to the Chiral Magnetic Effect, are computed in the model.

  6. K stability and stability of chiral ring

    CERN Document Server

    Collins, Tristan C; Yau, Shing-Tung

    2016-01-01

    We define a notion of stability for chiral ring of four dimensional N=1 theory by introducing test chiral rings and generalized a maximization. We conjecture that a chiral ring is the chiral ring of a superconformal field theory if and only if it is stable. We then study N=1 field theory derived from D3 branes probing a three-fold singularity X, and show that the K stability which implies the existence of Ricci-flat conic metric on X is equivalent to the stability of chiral ring of the corresponding field theory.

  7. Scaling laws in chiral hydrodynamic turbulence

    Science.gov (United States)

    Yamamoto, Naoki

    2016-06-01

    We study the turbulent regime of chiral (magneto)hydrodynamics for charged and neutral matter with chirality imbalance. We find that the chiral magnetohydrodynamics for charged plasmas possesses a unique scaling symmetry, only without fluid helicity under the local charge neutrality. We also find a different type of unique scaling symmetry in the chiral hydrodynamics for neutral matter with fluid helicity in the inertial range. We show that these symmetries dictate the self-similar inverse cascade of the magnetic and kinetic energies. Our results imply the possible inverse energy cascade in core-collapse supernovae due to the chiral transport of neutrinos.

  8. Ferrimagnetic/ferroelastic domain interactions in magnetite below the Verwey transition: Part II. Micromagnetic and image simulations

    DEFF Research Database (Denmark)

    Bryson, James F.J.; Kasama, Takeshi; Dunin-Borkowski, Rafal E.;

    2013-01-01

    Micromagnetic simulations have been used to explore the interaction between ferrimagnetic domain walls (DWs) and ferroelastic twin walls (TWs) below the Verwey transition in magnetite (Fe3O4). Simulations were performed using a thin-foil geometry in order to replicate the domain patterns observed...... experimentally using transmission electron microscopy. The magnetic microstructure is shown to be highly sensitive to the physical dimensions and crystallographic orientation of the foil, the spatial distribution and crystallographic classification of the TWs and the temperature/field history of the sample...

  9. Perpendicularly magnetized ferrimagnetic [Mn50Ga50/Co2FeAl] superlattice and the utilization in magnetic tunnel junctions

    Directory of Open Access Journals (Sweden)

    Q. L. Ma

    2015-08-01

    Full Text Available The ferrimagnetic superlattice (SL [MnGa/Co2FeAl]n exhibiting perpendicular magnetic anisotropy opened a new method for spintronics materials used in magnetic random access memory, because of the high anisotropy, small damping constant and tunable magnetization. In this work, we fabricated SLs with different MnGa composition and studied the MnGa composition dependence of the structure and magnetic properties of the SLs. Furthermore, we fabricated fully perpendicular magnetic tunnel junctions with SLs as both top and bottom electrodes. A clear tunnel magnetoresistance (TMR effect with TMR ratio of 1.3% at room temperature was observed.

  10. Perpendicularly magnetized ferrimagnetic [Mn50Ga50/Co2FeAl] superlattice and the utilization in magnetic tunnel junctions

    Science.gov (United States)

    Ma, Q. L.; Zhang, X. M.; Miyazaki, T.; Mizukami, S.

    2015-08-01

    The ferrimagnetic superlattice (SL) [MnGa/Co2FeAl]n exhibiting perpendicular magnetic anisotropy opened a new method for spintronics materials used in magnetic random access memory, because of the high anisotropy, small damping constant and tunable magnetization. In this work, we fabricated SLs with different MnGa composition and studied the MnGa composition dependence of the structure and magnetic properties of the SLs. Furthermore, we fabricated fully perpendicular magnetic tunnel junctions with SLs as both top and bottom electrodes. A clear tunnel magnetoresistance (TMR) effect with TMR ratio of 1.3% at room temperature was observed.

  11. First-principles study of ferroelectricity induced by p-d hybridization in ferrimagnetic NiFe2O4

    Science.gov (United States)

    Jong, Un-Gi; Yu, Chol-Jun; Park, Yong-Su; Ri, Chong-Suk

    2016-09-01

    We investigate the ferrimagnetism and ferroelectricity of bulk NiFe2O4 with tetragonal P41 22 symmetry by means of density functional theory calculations using generalized gradient approximation + Hubbard U approach. Special attention is paid to finding the most energetically favorable configuration on magnetic ordering and further calculating the reliable spontaneous electric polarization. With the fully optimized crystalline structure of the most stable configuration, the spontaneous polarization is obtained to be 23 μC/cm2 along the z direction, which originates from the hybridization between the 3d states of the Fe3+ cation and the 2p states of oxygen induced by Jahn-Teller effect.

  12. Interlayer exchange coupling in perpendicularly magnetized synthetic ferrimagnet structure using CoCrPt and CoFeB

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, D; Mizukami, S; Wu, F; Miyazaki, T [WPI-AIMR, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Oogane, M; Naganuma, H; Ando, Y, E-mail: watanabe@wpi-aimr.tohoku.ac.j [Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-05, Sendai 980-8579 (Japan)

    2010-01-01

    Interlayer exchange coupling in synthetic ferrimagnet structures consisting of perpendicularly magnetized CoCrPt and in-plane magnetized CoFeB layers, which are coupled by a Ru thin spacer, were investigated. The magnetization of the CoFeB layer turned perpendicular to the film plane after annealing at 300{sup 0}C because of the appearance of interlayer coupling from the CoCrPt layer. The coupling varied between antiferromagnetic and ferromagnetic depending on the Ru spacer thickness. The sign and strength of the coupling were also observed through analyses of magnetization curves and ferromagnetic resonance spectra.

  13. Preparation of optical active polydiacetylene through gelating and the control of supramolecular chirality

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the corresponding xerogel under UV-irradiation. Optically active polydiacetylene (PDA) were subsequently obtained. Supramolecular chirality of PDA could be controlled by the chirality of gelators. Left-handed and right-handed helical fibers were obtained by using Land D-gelators in xerogels respectively, and CD spectra exhibited mirror-image circular dichroism. The PDA in xerogel exhibited typical blue-to-red transition responsive to the temperature and pH, while the supramolecular chirality of PDA showed a corresponding change.

  14. Communication: Probing the absolute configuration of chiral molecules at aqueous interfaces

    International Nuclear Information System (INIS)

    We demonstrate that the enantiomers of chiral macromolecules at an aqueous interface can be distinguished with monolayer sensitivity using heterodyne-detected vibrational sum-frequency generation (VSFG). We perform VSFG spectroscopy with a polarization combination that selectively probes chiral molecular structures. By using frequencies far detuned from electronic resonances, we probe the chiral macromolecular structures with high surface specificity. The phase of the sum-frequency light generated by the chiral molecules is determined using heterodyne detection. With this approach, we can distinguish right-handed and left-handed helical peptides at a water-air interface. We thus show that heterodyne-detected VSFG is sensitive to the absolute configuration of complex, interfacial macromolecules and has the potential to determine the absolute configuration of enantiomers at interfaces

  15. Chiral liquid chromatography contribution to the determination of the absolute configuration of enantiomers.

    Science.gov (United States)

    Roussel, Christian; Del Rio, Alberto; Pierrot-Sanders, Johanna; Piras, Patrick; Vanthuyne, Nicolas

    2004-05-28

    The review covers examples in which chiral HPLC, as a source of pure enantiomers, has been combined with classical methods (X-ray, vibrational circular dichroism (VCD), enzymatic resolutions, nuclear magnetic resonance (NMR) techniques, optical rotation, circular dichroism (CD)) for the on- or off-line determination of absolute configuration of enantiomers. Furthermore, it is outlined that chiral HPLC, which associates enantioseparation process and classical purification process, opens new perspectives in the classical determination of absolute configuration by chemical correlation or chemical interconversion methods. The review also contains a discussion about the various approaches to predict the absolute configuration from the retention behavior of the enantiomers on chiral stationary phases (CSPs). Some examples illustrate the advantages and limitations of molecular modeling methods and the use of chiral recognition models. The assumptions underlying some of these methods are critically analyzed and some possible emerging new strategies are outlined. PMID:15214673

  16. Formulation of 2D Graphene Deformation Based on Chiral-Tube Base Vectors

    Directory of Open Access Journals (Sweden)

    Bohua Sun

    2010-01-01

    Full Text Available The intrinsic feature of graphene honeycomb lattice is defined by its chiral index (n,m, which can be taken into account when using molecular dynamics. However, how to introduce the index into the continuum model of graphene is still an open problem. The present manuscript adopts the continuum shell model with single director to describe the mechanical behaviors of graphene. In order to consider the intrinsic features of the graphene honeycomb lattice—chiral index (n,m, the chiral-tube vectors of graphene in real space have been used for construction of reference unit base vectors of the shell model; therefore, the formulations will contain the chiral index automatically, or in an explicit form in physical components. The results are quite useful for future studies of graphene mechanics.

  17. Communication: Probing the absolute configuration of chiral molecules at aqueous interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lotze, Stephan, E-mail: lotze@amolf.nl; Versluis, Jan [FOM Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam (Netherlands); Olijve, Luuk L. C.; Schijndel, Luuk van; Milroy, Lech G.; Voets, Ilja K. [Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Bakker, Huib J., E-mail: bakker@amolf.nl [FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands)

    2015-11-28

    We demonstrate that the enantiomers of chiral macromolecules at an aqueous interface can be distinguished with monolayer sensitivity using heterodyne-detected vibrational sum-frequency generation (VSFG). We perform VSFG spectroscopy with a polarization combination that selectively probes chiral molecular structures. By using frequencies far detuned from electronic resonances, we probe the chiral macromolecular structures with high surface specificity. The phase of the sum-frequency light generated by the chiral molecules is determined using heterodyne detection. With this approach, we can distinguish right-handed and left-handed helical peptides at a water-air interface. We thus show that heterodyne-detected VSFG is sensitive to the absolute configuration of complex, interfacial macromolecules and has the potential to determine the absolute configuration of enantiomers at interfaces.

  18. A chiral molecular conductor: synthesis, structure, and physical properties of [ET]3[Sb2(L-tart)2].CH3CN (ET = bis(ethylendithio)tetrathiafulvalene; L-tart = (2R,3R)-(+)-tartrate).

    Science.gov (United States)

    Coronado, Eugenio; Galán-Mascarós, José R; Gómez-García, Carlos J; Murcia-Martínez, Ana; Canadell, Enric

    2004-12-13

    The salt [ET](3)[Sb(2)(L-tart)(2)].CH(3)CN (1) has been obtained by electrocrystallization of the organic donor bis(ethylendithio)tetrathiafulvalene (ET or BEDT-TTF) in the presence of the chiral anionic complex [Sb(2)(L-tart)(2)](2-) (L-tart = (2R,3R)-(+)-tartrate). This salt crystallizes in the chiral space group P2(1)2(1)2(1) (a = 11.145(2) angstroms, b = 12.848(2) angstroms, c = 40.159(14) angstroms, V = 5750.4(14) angstroms(3), Z = 4) and is formed by alternating layers of the anions and of the organic radicals in a noncentrosymmetric alpha-type packing. This compound shows a room temperature electrical conductivity of approximately 1 S.cm(-1) and semiconducting behavior with an activation energy of approximately 85 meV. Analysis of the magnetic susceptibility and band structure, however, suggests that this compound should be a narrow band gap semiconductor.

  19. Thermal chiral vortical and magnetic waves: new excitation modes in chiral fluids

    CERN Document Server

    Kalaydzhyan, Tigran

    2016-01-01

    In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark-gluon plasma, liquid helium 3He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in a external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density, the chiral vortical and chiral magnetic waves. We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the excitation reduces to a charge diffusion mode or is completely absent. We also correct the dispersion relation for the chiral magnetic wave.

  20. Chiral Cosmological Models: Dark Sector Fields Description

    CERN Document Server

    Chervon, S V

    2014-01-01

    The present review is devoted to a Chiral Cosmological Model as the self-gravitating nonlinear sigma model with the potential of (self)interactions employed in cosmology. The chiral cosmological model has successive applications in descriptions of the inflationary epoch of the Universe evolution; the present accelerated expansion of the Universe also can be described by the chiral fields multiplet as the dark energy in wide sense. To be more illustrative we are often addressed to the two-component chiral cosmological model. Namely, the two-component chiral cosmological model describing the phantom field with interaction to a canonical scalar field is analyzed in details. New generalized model of quintom character is proposed and exact solutions are founded out. In the review we represented the perturbation theory for chiral cosmological model with the aim to describe the structure formation using the progress achieved in the inflation theory. It was shown that cosmological perturbations from chiral fields can...

  1. The chiral symplectic universality class

    OpenAIRE

    Asada, Yoichi; Slevin, Keith; Ohtsuki, Tomi

    2003-01-01

    We report a numerical investigation of localization in the SU(2) model without diagonal disorder. At the band center, chiral symmetry plays an important role. Our results indicate that states at the band center are critical. States away from the band center but not too close to the edge of the spectrum are metallic as expected for Hamiltonians with symplectic symmetry.

  2. Algebraic study of chiral anomalies

    Indian Academy of Sciences (India)

    Juan Mañes; Raymond Stora; Bruno Zumino

    2012-06-01

    The algebraic structure of chiral anomalies is made globally valid on non-trivial bundles by the introduction of a fixed background connection. Some of the techniques used in the study of the anomaly are improved or generalized, including a systematic way of generating towers of ‘descent equations’.

  3. Resolution of D- and L-glucoses by chiral N-octyl-beta-D-glycoside-Cu(II) complex adsorbed at the gas/liquid interface of small bubbles

    NARCIS (Netherlands)

    Sakai, M.; Miyazawa, K.; Jitsumatsu, H.; Kamio, K.; Mitsuiki, S.; Toh, N.; Sugihara, G.; Norde, W.

    2010-01-01

    A new technique of the jet drop method (JDM) was applied to a chiral molecular discrimination of optically active D- or L-glucose (guest) by chiral N-octyl-beta-D-glycoside (O beta DG)-Cu(II) complex (host) at the gas/liquid interface of small bubbles. The discrimination of glucoses as the guests is

  4. Hierarchical Assembly of a {Mn(II)15Mn(III)4} Brucite Disc: Step-by-Step Formation and Ferrimagnetism.

    Science.gov (United States)

    Deng, Yong-Kai; Su, Hai-Feng; Xu, Jia-Heng; Wang, Wen-Guang; Kurmoo, Mohamedally; Lin, Shui-Chao; Tan, Yuan-Zhi; Jia, Jiong; Sun, Di; Zheng, Lan-Sun

    2016-02-01

    In search of functional molecular materials and the study of their formation mechanism, we report the elucidation of a hierarchical step-by-step formation from monomer (Mn) to heptamer (Mn7) to nonadecamer (Mn19) satisfying the relation 1 + Σn6n, where n is the ring number of the Brucite structure using high-resolution electrospray ionization mass spectrometry (HRESI-MS). Three intermediate clusters, Mn10, Mn12, and Mn14, were identified. Furthermore, the Mn19 disc remains intact when dissolved in acetonitrile with a well-resolved general formula of [Mn19(L)x(OH)y(N3)36-x-y](2+) (x = 18, 17, 16; y = 8, 7, 6; HL = 1-(hydroxymethyl)-3,5-dimethylpyrazole) indicating progressive exchange of N3(-) for OH(-). The high symmetry (R-3) Mn19 crystal structure consists of a well-ordered discotic motif where the peripheral organic ligands form a double calix housing the anions and solvent molecules. From the formula and valence bond sums, the charge state is mixed-valent, [Mn(II)15Mn(III)4]. Its magnetic properties and electrochemistry have been studied. It behaves as a ferrimagnet below 40 K and has a coercive field of 2.7 kOe at 1.8 K, which can be possible by either weak exchange between clusters through the anions and solvents or through dipolar interaction through space as confirmed by the lack of ordering in frozen CH3CN. The moment of nearly 50 NμB suggests Mn(II)-Mn(II) and Mn(III)-Mn(III) are ferromagnetically coupled while Mn(II)-Mn(III) is antiferromagnetic which is likely if the Mn(III) are centrally placed in the cluster. This compound displays the rare occurrence of magnetic ordering from nonconnected high-spin molecules. PMID:26780000

  5. Exchange scattering as the driving force for ultrafast all-optical and bias-controlled reversal in ferrimagnetic metallic structures

    Science.gov (United States)

    Kalashnikova, A. M.; Kozub, V. I.

    2016-02-01

    Experimentally observed ultrafast all-optical magnetization reversal in ferrimagnetic metals and heterostructures based on antiferromagnetically coupled ferromagnetic d - and f -metallic layers relies on intricate energy and angular momentum flow between electrons, phonons, and spins. Here we treat the problem of angular momentum transfer in the course of ultrafast laser-induced dynamics in a ferrimagnetic metallic system using microscopical approach based on the system of rate equations. We show that the magnetization reversal is supported by a coupling of d and f subsystems to delocalized s or p electrons. The latter can transfer spin between the two subsystems in an incoherent way owing to the (s ;p )-(d ;f ) exchange scattering. Since the effect of the external excitation in this process is reduced to the transient heating of the mobile electron subsystem, we also discuss the possibility to trigger the magnetization reversal by applying a voltage bias pulse to antiferromagnetically coupled metallic ferromagnetic layers embedded in point contact or tunneling structures. We argue that such devices allow controlling reversal with high accuracy. We also suggest using the anomalous Hall effect to register the reversal, thus playing a role of reading probes.

  6. Solvent-induced helical assembly and reversible chiroptical switching of chiral cyclic-dipeptide-functionalized naphthalenediimides.

    Science.gov (United States)

    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

  7. 粒度均匀的分子印迹聚合物在手性拆分和生物分析中的应用%Uniformly Sized Molecularly Imprinted Polymers:Their Applications to Chiral Separation and Bioanalysis

    Institute of Scientific and Technical Information of China (English)

    HAGINAKA Jun; SANBE Haruyo

    2004-01-01

    Molecular recognition plays an important role in biological and chemical processes. Since molecular imprinting techniques can afford complementary binding sites for a target molecule, the molecularly imprinted polymer (MIP) for the target molecule has been used for its specific recognition as chromatographic media, solid-phase ex-

  8. Chiral extraction of ketoprofen enantiomers with chiral selector tartaric esters

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dan; LIU Jia-jia; TANG Ke-wen; HUANG Ke-long

    2007-01-01

    Distribution behavior of ketoprofen enantiomers was examined in methanol aqueous and organic solvent mixture containing tartaric esters. The influence of length of alkyl chain of tartaric esters, concentration of L-tartaric esters and methanol aqueous, kind of organic solvent on partition ratio and separation factors was investigated. The results show that L-tartaric and D-tartaric esters have different chiral recognition abilities. S-ketoprofen is easily extracted by L-tartaric esters, and R-ketoprofen is easily extracted by D-tartaric esters. L-tartaric esters form more stable diastereomeric complexes with S-enantiomer than that with R-enantiomer. This distribution behavior is consistent with chiral recognition mechanism. With the increase of the concentration of tartaric ester from 0 to 0.3 mol/L, partition coefficient K and separation factor α increase. Also, the kind of organic solvent and the concentration of the methanol aqueous have significant influence on K and α.

  9. Focusing, Power Tunneling and Rejection from Chiral and/or Chiral Nihility/Nihility Metamaterials Layers

    CERN Document Server

    Shah, Syed Touseef Hussain; Syed, Aqeel A; Naqvi, Qaisar Abbas

    2013-01-01

    Focusing of electromagnetic plane wave from a large size paraboloidal reflector, composed of layers of chiral and/or chiral nihility metamaterials, has been studied us- ing Maslov's method. First, the transmission and reflection of electromagnetic plane wave from two parallel layers of chiral and/or chiral nihility metamaterials are cal- culated using transfer matrix method. The effects of change of angle of incidence, chirality parameters and impedances of layers are noted and discussed. Special cases by taking very large and small values of permittivity of second layer, while assuming value of corresponding chirality equal to zero, are also treated. These special cases are equivalent to reflection from a perfect electric conductor backed chiral layer and nihility backed chiral layer, respectively. Results of reflection from parallel layers have been utilized to study focusing from a large size paraboloidal reflector. The present study, on focusing from a paraboloidal re{\\deg}ector, not only unifies several ...

  10. Chiral Fluorescent Receptors Based on (R)-1,1'-Binaphthylene-2,2'-bisthiourea: Synthesis and Chiral Recognition

    Institute of Scientific and Technical Information of China (English)

    隗兰华; 何永炳; 徐括喜; 刘顺英; 孟令芝

    2005-01-01

    Two chiral fluorescent receptors 1 and 2 based on (R)-1,1'-binaphthylene-2,2'-bisthiourea were synthesized, and their chiral recognition properties for enantiomeric mandelate anions were studied by fluorescence spectra and molecular modeling. Addition of the L- and D-mandelate anions caused considerable fluorescent increases in the fluorescent intensity of the host solution. The L-enantiomer can enhance the fluorescence intensity of 1 much more than the D-enantiomer can do, and 1 shows a better enantioselective recognition ability than 2.

  11. Asymmetric synthesis using chiral-encoded metal

    Science.gov (United States)

    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.

  12. Asymmetric synthesis using chiral-encoded metal.

    Science.gov (United States)

    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

  13. Anomalous Maxwell equations for inhomogeneous chiral plasma

    CERN Document Server

    Gorbar, E V; Vilchinskii, S; Rudenok, I; Boyarsky, A; Ruchayskiy, O

    2016-01-01

    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 charge 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 diffusion-like terms, we find also new dissipation-less terms that are independent of relaxation time. Their origin can be traced to the Berry curvature modifications of the kinetic theory.

  14. Anomalous Maxwell equations for inhomogeneous chiral plasma

    Science.gov (United States)

    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.

  15. Dynamic localization of electronic excitation in photosynthetic complexes revealed with chiral two-dimensional spectroscopy

    Science.gov (United States)

    Fidler, Andrew F.; Singh, Ved P.; Long, Phillip D.; Dahlberg, Peter D.; Engel, Gregory S.

    2014-02-01

    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.

  16. On chirality of slime mould.

    Science.gov (United States)

    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

  17. Bootstrapping N=2 chiral correlators

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Madalena [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Liendo, Pedro [Humboldt-Univ. Berlin (Germany). IMIP

    2015-12-15

    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.

  18. Chiral Particle Separation by a Nonchiral Microlattice

    Science.gov (United States)

    Bogunovic, Lukas; Fliedner, Marc; Eichhorn, Ralf; Wegener, Sonja; Regtmeier, Jan; Anselmetti, Dario; Reimann, Peter

    2012-09-01

    We conceived a model experiment for a continuous separation strategy of chiral molecules (enantiomers) without the need of any chiral selector structure or derivatization agents: Microparticles that only differ by their chirality are shown to migrate along different directions when driven by a steady fluid flow through a square lattice of cylindrical posts. In accordance with our numerical predictions, the transport directions of the enantiomers depend very sensitively on the orientation of the lattice relative to the fluid flow.

  19. Chiral phases of fundamental and adjoint quarks

    Energy Technology Data Exchange (ETDEWEB)

    Natale, A. A. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC 09210-170, Santo André, SP (Brazil); Instituto de Física Teórica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, São Paulo, SP (Brazil)

    2016-01-22

    We consider a QCD chiral symmetry breaking model where the gap equation contains an effective confining propagator and a dressed gluon propagator with a dynamically generated mass. This model is able to explain the ratios between the chiral transition and deconfinement temperatures in the case of fundamental and adjoint quarks. It also predicts the recovery of the chiral symmetry for a large number of quarks (n{sub f} ≈ 11 – 13) in agreement with lattice data.

  20. Infinite Chiral Symmetry in Four Dimensions

    CERN Document Server

    Beem, Christopher; Liendo, Pedro; Peelaers, Wolfger; Rastelli, Leonardo; van Rees, Balt C

    2015-01-01

    We describe a new correspondence between four-dimensional conformal field theories with extended supersymmetry and two-dimensional chiral algebras. The meromorphic correlators of the chiral algebra compute correlators in a protected sector of the four-dimensional theory. Infinite chiral symmetry has far-reaching consequences for the spectral data, correlation functions, and central charges of any four-dimensional theory with ${\\mathcal N}=2$ superconformal symmetry.

  1. Random Matrix Theory and Chiral Logarithms

    OpenAIRE

    Berbenni-Bitsch, M. E.; Göckeler, M.; Hehl, H.; Meyer, S.; Rakow, P. E. L.; Schäfer, A.; Wettig, T.

    1999-01-01

    Abstract: Recently, the contributions of chiral logarithms predicted by quenched chiral perturbation theory have been extracted from lattice calculations of hadron masses. We argue that a detailed comparison of random matrix theory and lattice calculations allows for a precise determination of such corrections. We estimate the relative size of the m log(m), m, and m^2 corrections to the chiral condensate for quenched SU(2).

  2. A spectral route to determining chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

    We show how one-dimensional structured media can be used to measure chirality, via the spectral shift of the photonic band gap edges. Analytically, we show that a chiral contrast can, in some cases, be mapped unto an index contrast, thereby greatly simplifying the analysis of such structures. Using...... this mapping, we derive a first-order shift of the band gap edges with chirality. Potentially, this effect could be used for measuring enantiomeric excess....

  3. Chiral magnetic effect by synthetic gauge fields

    CERN Document Server

    Hayata, Tomoya

    2016-01-01

    We study the dynamical generation of the chiral chemical potential in a Weyl metal constructed from a three-dimensional optical lattice and subject to synthetic gauge fields. By numerically solving the Boltzmann equation with the Berry curvature in the presence of parallel synthetic electric and magnetic fields, we find that the spectral flow and the ensuing chiral magnetic current emerge. We show that the spectral flow and the chiral chemical potential can be probed by time-of-flight imaging.

  4. Majorana Neutrino: Chirality and Helicity

    CERN Document Server

    Dvoeglazov, Valeriy V

    2012-01-01

    We introduce the Majorana spinors in the momentum representation. They obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). Particular attention has been paid to the questions of chirality and helicity (two concepts which frequently are confused in the literature) for Dirac and Majorana states.

  5. An epistemological note on chirality

    International Nuclear Information System (INIS)

    The terms ''chiral'' and ''achiral'' are sharply defined when applied to geometric figures or models. The same terms are also commonly used to refer to the real systems to which these models have been adjoined. e.g., molecules, solvents, or reagents. Here, the terms are not sharply defined but depend upon conditions or measurement. The contrast between the geometric and operational usages is discussed in detail

  6. Staggered chiral random matrix theory

    International Nuclear Information System (INIS)

    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.

  7. Chiral Separation of Erythromycin as a New Chiral Selector on CE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Erythromycin as a new chiral selector was first used for chrial separation of four derivatives of biphenyldimethylester enantiomers on CE. The influence of pH, the chiral selector concentration and organic modifiers were preliminarily studied. Experiments show that the erythromycin as chiral selector is useful to CE.

  8. Chiral Induction with Chiral Conformational Switches in the Limit of Low "Sergeants to Soldiers" Ratio

    DEFF Research Database (Denmark)

    Nuermaimaiti, Ajiguli; Bombis, Christian; Knudsen, Martin Markvard;

    2014-01-01

    " mechanism for an oligo(phenylene ethynylene) based chiral conformational switch by coadsorbing it with an intrinsically chiral seed on Au(111). Through statistical analysis of scanning tunneling microscopy (STM) data we demonstrate successful chiral induction with a very low concentration of seeding...

  9. X-ray structure of [ReCl4(mu-ox)Cu(pyim)2]: a new heterobimetallic Re(IV)Cu(II) ferrimagnetic chain.

    Science.gov (United States)

    Martínez-Lillo, José; Armentano, Donatella; De Munno, Giovanni; Lloret, Francesc; Julve, Miguel; Faus, Juan

    2008-01-01

    A new heterobimetallic Re(IV)Cu(II) compound has been prepared and its crystal structure determined by single-crystal X-ray diffraction; magnetic susceptibility measurements show that this compound behaves as a ferrimagnetic chain with significant antiferromagnetic interactions between Re(IV) and Cu(II) metal ions.

  10. Recent Theoretical and Experimental Advances in the Electronic Circular Dichroisms of Planar Chiral Cyclophanes

    Science.gov (United States)

    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.

  11. Nanocatalyst structure as a template to define chirality of nascent single-walled carbon nanotubes.

    Science.gov (United States)

    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.

  12. Nanocatalyst structure as a template to define chirality of nascent single-walled carbon nanotubes.

    Science.gov (United States)

    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

  13. Chiral symmetry and functional integral

    Energy Technology Data Exchange (ETDEWEB)

    Gamboa Saravi, R.E.; Muschietti, M.A.; Schaposnik, F.A.; Solomin, J.E.

    1984-10-15

    The change in the fermionic functional integral measure under chiral rotations is analyzed. Using the zeta-function method, the evaluation of chiral Jacobians to theories including non-hermitian Dirac operators D, can be extended in a natural way. (This being of interest, for example, in connection with the Weinberg-Salam model or with the relativistic string theory). Results are compared with those obtained following other approaches, the possible discrepancies are analyzed and the equivalence of the different methods under certain conditions on D is proved. Also shown is how to compute the Jacobian for the case of a finite chiral transformation and this result is used to develop a sort of path-integral version of bosonization in d = 2 space-time dimensions. This result is used to solve in a very simple and economical way relevant d = 2 fermionic models. Furthermore, some interesting features in connection with the theta-vacuum in d = 2,4 gauge theories are discussed.

  14. Chiral primaries in strange metals

    Energy Technology Data Exchange (ETDEWEB)

    Isachenkov, Mikhail, E-mail: mikhail.isachenkov@desy.de; Kirsch, Ingo, E-mail: ingo.kirsch@desy.de; Schomerus, Volker, E-mail: volker.schomerus@desy.de

    2014-08-15

    It was suggested recently that the study of 1-dimensional QCD with fermions in the adjoint representation could lead to an interesting toy model for strange metals and their holographic formulation. In the high density regime, the infrared physics of this theory is described by a constrained free fermion theory with an emergent N=(2,2) superconformal symmetry. In order to narrow the choice of potential holographic duals, we initiate a systematic search for chiral primaries in this model. We argue that the bosonic part of the superconformal algebra can be extended to a coset chiral algebra of the form W{sub N}=SO(2N{sup 2}−2){sub 1}/SU(N){sub 2N}. In terms of this algebra the spectrum of the low energy theory decomposes into a finite number of sectors which are parametrized by special necklaces. We compute the corresponding characters and partition functions and determine the set of chiral primaries for N≤5.

  15. Chiral primaries in strange metals

    Energy Technology Data Exchange (ETDEWEB)

    Isachenkov, Mikhail; Kirsch, Ingo; Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group

    2014-03-15

    It was suggested recently that the study of 1-dimensional QCD with fermions in the adjoint representation could lead to an interesting toy model for strange metals and their holographic formulation. In the high density regime, the infrared physics of this theory is described by a constrained free fermion theory with an emergent N=(2,2) superconformal symmetry. In order to narrow the choice of potential holographic duals, we initiate a systematic search for chiral primaries in this model. We argue that the bosonic part of the superconformal algebra can be extended to a coset chiral algebra of the form W{sub N}=SO(2N{sup 2}-2){sub 1}/SU(N){sub 2N}. In terms of this algebra the spectrum of the low energy theory decomposes into a finite number of sectors which are parametrized by special necklaces. We compute the corresponding characters and partition functions and determine the set of chiral primaries for N≤5.

  16. Chiral symmetry breaking and monopoles

    CERN Document Server

    Di Giacomo, Adriano; Pucci, Fabrizio

    2015-01-01

    To understand the relation between the chiral symmetry breaking and monopoles, the chiral condensate which is the order parameter of the chiral symmetry breaking is calculated in the $\\overline{\\mbox{MS}}$ scheme at 2 [GeV]. First, we add one pair of monopoles, varying the monopole charges $m_{c}$ from zero to four, to SU(3) quenched configurations by a monopole creation operator. The low-lying eigenvalues of the Overlap Dirac operator are computed from the gauge links of the normal configurations and the configurations with additional monopoles. Next, we compare the distributions of the nearest-neighbor spacing of the low-lying eigenvalues with the prediction of the random matrix theory. The low-lying eigenvalues not depending on the scale parameter $\\Sigma$ are compared to the prediction of the random matrix theory. The results show the consistency with the random matrix theory. Thus, the additional monopoles do not affect the low-lying eigenvalues. Moreover, we discover that the additional monopoles increa...

  17. Lateral chirality-sorting optical forces

    Science.gov (United States)

    Hayat, Amaury; Mueller, J. P. Balthasar; Capasso, Federico

    2015-01-01

    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

  18. Implications of Local Chiral Symmetry Breaking

    CERN Document Server

    La, H S

    2003-01-01

    The spontaneous symmetry breaking of a local chiral symmetry to its diagonal vector symmetry naturally realizes a complete geometrical structure more general than that of Yang-Mills (YM) theory, rather similar to that of gravity. A good example is the Quantum Chromodynamics (QCD) with respect to the Chiral Color model. Also, a new anomaly-free particle content for a Chiral Color model is introduced: the Chiral Color can be realized without introducing whole new generations of quarks and leptons, but by simply enlarging each generation with new exotic fermions.

  19. Multicomponent, peptide-targeted glycol chitosan nanoparticles containing ferrimagnetic iron oxide nanocubes for bladder cancer multimodal imaging

    Directory of Open Access Journals (Sweden)

    Key J

    2016-08-01

    Full Text Available Jaehong Key,1,2 Deepika Dhawan,3 Christy L Cooper,3,4 Deborah W Knapp,3 Kwangmeyung Kim,5 Ick Chan Kwon,5 Kuiwon Choi,5 Kinam Park,1,6 Paolo Decuzzi,7–9 James F Leary1,3,41Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA; 2Department of Biomedical Engineering, Yonsei University, Wonju, Republic of Korea; 3School of Veterinary Medicine-Department of Basic Medical Sciences, Purdue University, West Lafayette, 4Birck Nanotechnology Center at Discovery Park, Purdue University, West Lafayette, IN, USA; 5Biomedical Research Center, Korea Institute of Science and Technology, Sungbook-Gu, Seoul, Republic of Korea; 6Department of Pharmaceutics, Purdue University, West Lafayette, IN, 7Department of Translational Imaging, 8Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX USA; 9Laboratory of Nanotechnology for Precision Medicine, Fondazione Istituto Italiano di Tecnologia (IIT, Genova, Italy Abstract: While current imaging modalities, such as magnetic resonance imaging (MRI, computed tomography, and positron emission tomography, play an important role in detecting tumors in the body, no single-modality imaging possesses all the functions needed for a complete diagnostic imaging, such as spatial resolution, signal sensitivity, and tissue penetration depth. For this reason, multimodal imaging strategies have become promising tools for advanced biomedical research and cancer diagnostics and therapeutics. In designing multimodal nanoparticles, the physicochemical properties of the nanoparticles should be engineered so that they successfully accumulate at the tumor site and minimize nonspecific uptake by other organs. Finely altering the nano-scale properties can dramatically change the biodistribution and tumor accumulation of nanoparticles in the body. In this study, we engineered multimodal nanoparticles for both MRI, by using ferrimagnetic nanocubes (NCs, and near infrared fluorescence imaging

  20. Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

    Directory of Open Access Journals (Sweden)

    Sara J. Krivickas

    2015-09-01

    Full Text Available Chiral molecular crystals built up by chiral molecules without inversion centers have attracted much interest owing to their versatile functionalities related to optical, magnetic, and electrical properties. However, there is a difficulty in chiral crystal growth due to the lack of symmetry. Therefore, we made the molecular design to introduce intermolecular hydrogen bonds in chiral crystals. Racemic and enantiopure bis(ethylenedithiotetrathiafulvalene (BEDT-TTF derivatives possessing hydroxymethyl groups as the source of hydrogen bonds were designed. The novel racemic trans-vic-(hydroxymethyl(methyl-BEDT-TTF 1, and racemic and enantiopure trans-vic-bis(hydroxymethyl-BEDT-TTF 2 were synthesized. Moreover, the preparations, crystal structure analyses, and electrical resistivity measurements of the novel achiral charge transfer salt θ21-[(S,S-2]3[(R,R-2]3(ClO42 and the chiral salt α’-[(R,R-2]ClO4(H2O were carried out. In the former θ21-[(S,S-2]3[(R,R-2]3(ClO42, there are two sets of three crystallographically independent donor molecules [(S,S-2]2[(R,R-2] in a unit cell, where the two sets are related by an inversion center. The latter α’-[(R,R-2]ClO4(H2O is the chiral salt with included solvent H2O, which is not isostructural with the reported chiral salt α’-[(S,S-2]ClO4 without H2O, but has a similar donor arrangement. According to the molecular design by introduction of hydroxy groups and a ClO4− anion, many intermediate-strength intermolecular hydrogen bonds (2.6–3.0 Å were observed in these crystals between electron donor molecules, anions, and included H2O solvent, which improve the crystallinity and facilitate the extraction of physical properties. Both salts are semiconductors with relatively low resistivities at room temperature and activation energies of 1.2 ohm cm with Ea = 86 meV for θ21-[(S,S-2]3[(R,R-2]3(ClO42 and 0.6 ohm cm with Ea = 140 meV for α'-[(R,R-2]2ClO4(H2O, respectively. The variety of donor arrangements

  1. Coexistence of both gyroid chiralities in individual butterfly wing scales of Callophrys rubi.

    Science.gov (United States)

    Winter, Benjamin; Butz, Benjamin; Dieker, Christel; Schröder-Turk, Gerd E; Mecke, Klaus; Spiecker, Erdmann

    2015-10-20

    The wing scales of the Green Hairstreak butterfly Callophrys rubi consist of crystalline domains with sizes of a few micrometers, which exhibit a congenitally handed porous chitin microstructure identified as the chiral triply periodic single-gyroid structure. Here, the chirality and crystallographic texture of these domains are investigated by means of electron tomography. The tomograms unambiguously reveal the coexistence of the two enantiomeric forms of opposite handedness: the left- and right-handed gyroids. These two enantiomers appear with nonequal probabilities, implying that molecularly chiral constituents of the biological formation process presumably invoke a chiral symmetry break, resulting in a preferred enantiomeric form of the gyroid structure. Assuming validity of the formation model proposed by Ghiradella H (1989) J Morphol 202(1):69-88 and Saranathan V, et al. (2010) Proc Natl Acad Sci USA 107(26):11676-11681, where the two enantiomeric labyrinthine domains of the gyroid are connected to the extracellular and intra-SER spaces, our findings imply that the structural chirality of the single gyroid is, however, not caused by the molecular chirality of chitin. Furthermore, the wing scales are found to be highly textured, with a substantial fraction of domains exhibiting the directions of the gyroid crystal aligned parallel to the scale surface normal. Both findings are needed to completely understand the photonic purpose of the single gyroid in gyroid-forming butterflies. More importantly, they show the level of control that morphogenesis exerts over secondary features of biological nanostructures, such as chirality or crystallographic texture, providing inspiration for biomimetic replication strategies for synthetic self-assembly mechanisms.

  2. The Optical Chirality Flux as a Useful Far-Field Probe of Chiral Near Fields

    CERN Document Server

    Poulikakos, Lisa V; McPeak, Kevin M; Burger, Sven; Niegemann, Jens; Hafner, Christian; Norris, David J

    2016-01-01

    To optimize the interaction between chiral matter and highly twisted light, quantities that can help characterize chiral electromagnetic fields near nanostructures are needed. Here, by analogy with Poynting's theorem, we formulate the time-averaged conservation law of optical chirality in lossy dispersive media and identify the optical chirality flux as an ideal far-field observable for characterizing chiral optical near fields. Bounded by the conservation law, we show that it provides precise information, unavailable from circular dichroism spectroscopy, on the magnitude and handedness of highly twisted fields near nanostructures.

  3. Synthesis and Chiral Recognition of a New Type of Chiral Calix[4]arene Derivatives

    Institute of Scientific and Technical Information of China (English)

    HE,Yong-Bing; LI,Jian-Feng; XIAO,Yuan-Jing; WEI,Lan-Hua; WU,Xiao-Jun; MENG,Ling-Zhi

    2003-01-01

    Two new chiral calix[4] arenes bearing chiral pendants, which were from by-product of the antibiotic industry, were synthesized and characterized by 1H NMR, MS-FAB and elemental analysis. Studies of 1H NMR of the two calix [4] arene derivatives indicate that they exist in cone conformation in solution. Results of chiral recognition of the two chiral ligands 2a and 2b towards the tartaric acid derivative 3 show that ligand 2a exhibited good chiral recognition abilities compared to ligand 2b.

  4. Laser-induced precession of magnetization in ferrimagnetic GdFe thin films with low power excitation

    Directory of Open Access Journals (Sweden)

    K. Nishibayashi

    2013-03-01

    Full Text Available We have investigated thermal effects on the dynamics of laser-induced precession of magnetization in ferrimagnetic GdFe thin films under low-excitation conditions (6-60 μJ/cm2. An increase in quasi-equilibrium temperature by laser heating causes a shift in precession frequency, which is explained analytically by the alteration of the magnetic anisotropy field by 2.2 [Oe] at a pulse fluence of 1 μJ/cm2. We have also demonstrated coherent control of the precession amplitude using a sequence of two laser pulses, each with a fluence of 18 μJ/cm2, and point out the importance of low-power excitation for precise control of the dynamic states.

  5. First-principles study on the ferrimagnetic half-metallic Mn{sub 2}FeAs alloy

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Santao [Institute for Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Chuan-Hui, E-mail: zhangch@ustb.edu.cn [National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083 (China); Chen, Bao; Shen, Jiang [Institute for Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Chen, Nanxian [Institute for Applied Physics, University of Science and Technology Beijing, Beijing 100083 (China); Department of Physics, Tsinghua University, Beijing 100084 (China)

    2015-05-15

    Mn-based full-Heusler alloys are kinds of promising candidates for new half-metallic materials. Basing on first principles, the electronic structures and magnetic properties of the Mn{sub 2}FeAs full-Heusler alloy have been investigated in detail. The Hg{sub 2}CuTi-type Mn{sub 2}FeAs compound obeys the Slater-Pauling rule, while the anti-parallel alignment atomic magnetic moments of Mn locating at different sites indicate it a ferrimagnetic alloy. The calculated spin-down bands behave half-metallic character, exhibiting a direct gap of 0.46 eV with a 100% spin polarization at the Fermi level. More studies show the compound would maintain half-metallic nature in a large range of variational lattice constants. We expect that our calculated results may trigger Mn{sub 2}FeAs applying in the future spintronics field. - Graphical abstract: The d orbitals of Mn and Fe atoms split into multi-degenerated levels which create new bonding and nonbonding states. These exchange splitting shift the Fermi level to origin band gap.▪ - Highlights: • The electronic structure and magnetic properties of Mn{sub 2}FeAs full-Heusler alloy were studied. • A total magnetic moment of 3μ{sub B} was obtained for Mn{sub 2}FeAs alloy, following the SP rule M{sub t}=Z{sub t}−24. • The origin of ferrimagnetism and half-metallic character in Mn{sub 2}FeAs were discussed.

  6. Significance of the direct relaxation process in the low-energy spin dynamics of a one-dimensional ferrimagnet NiCu(C 7H 6N 2O 6)(H 2O) 3·2H 2O

    Science.gov (United States)

    Yamamoto, S.

    2000-11-01

    In response to recent nuclear magnetic resonance measurements on a ferrimagnetic chain compound NiCu(C 7H 6N 2O 6)(H 2O) 3·2H 2O [Solid State Commun. 113 (2000) 433], we calculate the nuclear spin-lattice relaxation rate 1/ T1 in terms of a modified spin-wave theory. Emphasizing that the dominant relaxation mechanism arises from the direct (single-magnon) process rather than the Raman (two-magnon) one, we explain the observed temperature and applied-field dependences of 1/ T1. Ferrimagnetic relaxation phenomena are generally discussed and novel ferrimagnets with extremely slow dynamics are predicted.

  7. Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures

    CERN Document Server

    Tian, Xiaorui; Sun, Mengtao

    2015-01-01

    Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of...

  8. Complete chiral symmetry breaking of an amino acid derivative directed by circularly polarized light

    NARCIS (Netherlands)

    Noorduin, Wim L.; Bode, Arno A.C.; Meijden, Maarten van der; Meekes, Hugo; Etteger, Albert F. van; Enckevort, Willem J.P. van; Christianen, Peter C.M.; Kaptein, Bernard; Kellogg, Richard M.; Rasing, Theo; Vlieg, Elias

    2009-01-01

    Circularly polarized light (CPL) emitted from star-forming regions is an attractive candidate as a cause of single chirality in nature. It has remained difficult, however, to translate the relatively small chemical effects observed on irradiation of molecular systems with CPL into high enantiomeric

  9. DEVELOPMENT AND REGISTRATION OF CHIRAL DRUGS

    NARCIS (Netherlands)

    WITTE, DT; ENSING, K; FRANKE, JP; DEZEEUW, RA

    1993-01-01

    In this review we describe the impact of chirality on drug development and registration in the United States, Japan and the European Community. Enantiomers may have differences in their pharmacological profiles, and, therefore, chiral drugs ask for special analytical and pharmacological attention du

  10. Orientation-Dependent Handedness and Chiral Design

    Science.gov (United States)

    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.

  11. Chiral Anomaly in Toroidal Carbon Nanotubes

    OpenAIRE

    Sasaki, K.

    2001-01-01

    It is pointed out that the chiral anomaly in 1+1 dimensions should be observed in toroidal carbon nanotubes on a planar geometry with varying magnetic field. We show that the chiral anomaly is closely connected with the persistent current in a one-dimensional metallic ring.

  12. An Extended Chiral SU(3) Quark Model

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zong-Ye; YU You-Wen; WANG Ping; DAI Lian-Rong

    2003-01-01

    The chiral SU(3) quark model is extended by including the vector meson exchanges to describe the short range interactions. The phase shifts of NN scattering are studied in this model. Compared with the results of the chiral SU(3) quark model in which only the pseudo-scalar and scalar chiralfields are considered, the phase shifts of 1 So wave are obviously improved.

  13. Generalized electromagnetic fields in a chiral medium

    Science.gov (United States)

    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.

  14. Generalized Electromagnetic fields in Chiral Medium

    OpenAIRE

    Bisht, P. S.; Singh, Jivan; Negi, O. P. S.

    2007-01-01

    The time dependent Dirac-Maxwell's Equations in presence of electric and magnetic sources are written in chiral media and the solutions for the classical problem are obtained in unique simple and consistent manner. The quaternion reformulation of generalized electromagnetic fields in chiral media has also been developed in compact, simple and consistent manner.

  15. Generalized electromagnetic fields in a chiral medium

    Energy Technology Data Exchange (ETDEWEB)

    Bisht, P S [Department of Physics, Kumaun University, Soban Singh Jeena Campus, Almora-263601 (Uttarakhand) (India); Singh, Jivan [Department of Physics, Govt. Post Graduate College, Pithoragarh (Uttarakhand) (India); Negi, O P S [Department of Physics, Kumaun University, Soban Singh Jeena Campus, Almora-263601 (Uttarakhand) (India)

    2007-09-14

    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.

  16. Partial quenching and chiral symmetry breaking

    OpenAIRE

    Creutz, Michael

    2014-01-01

    Partially quenched chiral perturbation theory assumes that valence quarks propagating on gauge configurations prepared with sea quarks of different masses will form a chiral condensate as the valence quark mass goes to zero. I present a counterexample involving non-degenerate sea quarks where the valence condensate does not form.

  17. LINEARLY POLARIZED PROBES OF SURFACE CHIRALITY

    NARCIS (Netherlands)

    VERBIEST, T; KAURANEN, M; MAKI, JJ; TEERENSTRA, MN; SCHOUTEN, AJ; NOLTE, RJM; PERSOONS, A

    1995-01-01

    We present a new nonlinear optical technique to study surface chirality. We demonstrate experimentally that the efficiency of second-harmonic generation from isotropic chiral surfaces is different for excitation with fundamental light that is +45 degrees and -45 degrees linearly polarized with respe

  18. A review of recent advances in mass spectrometric methods for gas-phase chiral analysis of pharmaceutical and biological compounds.

    Science.gov (United States)

    Wu, Lianming; Vogt, Frederick G

    2012-10-01

    Chirality has been of great interest in pharmaceutical and biological sciences. The capabilities of mass spectrometry (MS) for rapid analysis of complex mixtures have encouraged its exploration for gas-phase chiral differentiation. Although particular instances of successful discrimination between enantiomers have been reported over the past three decades, a general method of quantitative chiral analysis by MS has only been demonstrated recently. This review describes the current state of the chiral MS methods without chiral chromatographic separation, which fall into five main categories: (1) the kinetic method, (2) host-guest (H-G) diastereomeric adduct formation, (3) ion/molecule (equilibrium) reactions, (4) collision-induced dissociation (CID) of diastereomeric adducts, and (5) the emerging technique for gas-phase separation using ion mobility spectrometry (IMS). It emphasizes tandem mass spectrometry (MS/MS), which provides several unique analytical advantages for quantitative chiral analysis. These include intrinsically high sensitivity, molecular specificity, and tolerance to impurities as well as the simplicity and speed of the mass spectrometric measurements. Practical prospects and current challenges in quantitative chiral MS techniques for QbD (quality-by-design)-based pharmaceutical applications are also discussed. PMID:22579598

  19. Lambda Hypernuclei in a Chiral Hadronic Model

    Institute of Scientific and Technical Information of China (English)

    LIANG Yin-Hua; GUO Hua

    2005-01-01

    @@ Nuclear matter calculations in a chiral hadronic model have been performed. It has been found that the scalar and the vector potentials and binding energies per nucleon in the chiral hadronic model are very close to those of the microscopic relativistic Brueckner-Hartree-Fock calculations. The good results for finite nuclei can be obtained in the mean field approximation only if scalar mass ms and coupling constant gs have been improved with the fixed values of cs2 ≡ g2s(M/ms)2 as those given by the original parameter sets of the chiral hadronic model. Then the chiral hadronic model is extended to lambda hypernuclei. Our results predicted by the chiral hadronic model are compared with those by the nonlinear Walecka model. It has been shown that the hadronic model can also be used to describe lambda hypernuclei successfully.

  20. Chiral Superfluidity for the Heavy Ion Collisions

    CERN Document Server

    Kalaydzhyan, T

    2013-01-01

    We argue that the strongly coupled quark-gluon plasma formed at LHC and RHIC can be considered as a chiral superfluid. The "normal" component of the fluid is the thermalized matter in common sense, while the "superfluid" part consists of long wavelength (chiral) fermionic states moving independently. We use the bosonization procedure with a finite cut-off and obtain a dynamical axion-like field out of the chiral fermionic modes. Then we use relativistic hydrodynamics for macroscopic description of the effective theory obtained after the bosonization. Finally, solving the hydrodynamic equations in gradient expansion, we find that in the presence of external electromagnetic fields the motion of the "superfluid" component gives rise to the chiral magnetic, chiral electric and dipole wave effects. Latter two effects are specific for a two-component fluid, which provides us with crucial experimental tests of the model. By considering probe quarks one can show that the fermionic spectrum at the intermediate tempera...

  1. Stereochemical configuration and selective excitation of the chiral molecule halothane

    CERN Document Server

    Pitzer, Martin; Burzynski, Phillip; Weller, Miriam; Metz, Daniel; Neff, Jonathan; Waitz, Markus; Trinter, Florian; Schmidt, Lothar Ph H; Williams, Joshua B; Jahnke, Till; Schmidt-Böcking, Horst; Berger, Robert; Dörner, Reinhard; Schöffler, Markus

    2016-01-01

    X-ray single-photon ionization and fragmentation of the chiral molecule halothane (CHBrClCF${}_{3}$) from a racemic mixture have been investigated using the COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) technique. Two important facets related to the core ionization of this species are examined: Firstly, the distinction of enantiomers (mirror isomers) and the determination of absolute configuration on a single-molecule level by four-body Coulomb explosion; secondly, the interplay of site-selective excitation and fragmentation patterns. These results are easily transferrable to other molecular species and show the wealth of features

  2. Status of chiral meson physics

    Energy Technology Data Exchange (ETDEWEB)

    Bijnens, Johan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE 22362 Lund (Sweden)

    2016-01-22

    This talk includes a short introduction to Chiral Perturbation Theory in the meson sector concentrating on a number of recent developments. I discuss the latest fit of the low-energy constants. Finite volume corrections are discussed for the case with twisted boundary conditions for form-factors and first results at two-loops for three flavours for masses. The last part discusses the extension to other symmetry breaking patterns relevant for technicolour and related theories as well as the calculation of leading logarithms to high loop orders.

  3. Teleporting Superpositions of Chiral Amplitudes

    CERN Document Server

    Maierle, C S; Harris, R A; Maierle, Christopher S.; Lidar, Daniel A.; Harris, Robert A.

    1998-01-01

    Chiral molecules may exist in superpositions of left- and right-handed states. We show how the amplitudes of such superpositions may be teleported to the polarization degrees of freedom of a photon. Two experimental schemes are proposed, one leading to perfect, the other to state-dependent teleportation. Both methods yield complete information about the amplitudes. This is the first explicit example of "inter-species" teleportation, where the amplitudes of the quantum superposition of one species are transferred at the end of the process to a different species. The latter is then easily accessible for measurement.

  4. Observation of enhanced chiral asymmetries in the inner-shell photoionization of uniaxially oriented methyloxirane enantiomers

    CERN Document Server

    Tia, Maurice; Kastirke, Gregor; Gatzke, Janine; Kim, Hong-Keun; Trinter, Florian; Rist, Jonas; Hartung, Alexander; Trabert, Daniel; Siebert, Juliane; Henrichs, Kevin; Becht, Jasper; Zeller, Stefan; Gassert, Helena; Wiegandt, Florian; Wallauer, Robert; Kuhlins, Andreas; Schober, Carl; Bauer, Tobias; Wechselberger, Natascha; Burzynski, Phillip; Neff, Jonathan; Weller, Miriam; Metz, Daniel; Kircher, Max; Waitz, Markus; Williams, Joshua B; Schmidt, Lothar; Mueller, Anne D; Knie, Andre; Hans, Andreas; Ltaief, Ltaief Ben; Ehresmann, Arno; Berger, Robert; Fukuzawa, Hironobu; Ueda, Kiyoshi; Schmidt-Boecking, Horst; Doerner, Reinhard; Jahnke, Till; Demekhin, Philipp V; Schoeffler, Markus

    2016-01-01

    Most large molecules are chiral in their structure: they exist as two enantiomers, which are mirror images of each other. Whereas the rovibronic sublevels of two enantiomers are almost identical, it turns out that the photoelectric effect is sensitive to the absolute configuration of the ionized enantiomer - an effect termed Photoelectron Circular Dichroism (PECD). Our comprehensive study demonstrates that the origin of PECD can be found in the molecular frame electron emission pattern connecting PECD to other fundamental photophysical effects as the circular dichroism in angular distributions (CDAD). Accordingly, orienting a chiral molecule in space enhances the PECD by a factor of about 10.

  5. Atomic Structure and Energy Distribution of Collapsed Carbon Nanotubes of Different Chiralities

    Directory of Open Access Journals (Sweden)

    Julia A. Baimova

    2015-01-01

    Full Text Available For carbon nanotubes of sufficiently large diameter at sufficiently low temperature, due to the action of the van der Waals forces, the ground state is a bilayer graphene with closed edges, the so-called collapsed configuration. Molecular dynamics simulation of collapsed carbon nanotubes is performed. The effect of length, diameter, and chirality of the nanotubes on their properties is investigated. It is shown that collapsed nanotubes after relaxation have rippled structure which is strongly dependent on the nanotube chirality. The structural properties are studied by calculating the radial distribution function and energy distribution along various regions in the collapsed carbon nanotubes.

  6. Synthesis and characterization of mixed ligand chiral nanoclusters

    OpenAIRE

    Güven, Zekiye Pelin; Guven, Zekiye Pelin; Üstbaş, Burçin; Ustbas, Burcin; Harkness, Kellen M.; Coşkun, Hikmet; Coskun, Hikmet; Joshi, Chakra P.; Besong, Tabot M. D.; Stellacci, Francesco; Bakr, Osman M.; Akbulut, Özge; Akbulut, Ozge

    2015-01-01

    Chiral mixed ligand silver nanoclusters were synthesized in the presence of a chiral and an achiral ligand. The ratio of the ligands was changed to track the formation of these clusters. While the chiral ligand lead to nanoparticles, Presence of the achiral ligand induced the formation of nanoclusters with chiral properties.

  7. Synthesis and characterization of mixed ligand chiral nanoclusters

    KAUST Repository

    Guven, Zekiye P.

    2016-06-22

    Chiral mixed ligand silver nanoclusters were synthesized in the presence of a chiral and an achiral ligand. While the chiral ligand led mostly to the formation of nanoparticles, the presence of the achiral ligand drastically increased the yield of nanoclusters with enhanced chiral properties. © 2016 The Royal Society of Chemistry.

  8. Chiral sine-Gordon model

    CERN Document Server

    Yanagisawa, Takashi

    2016-01-01

    We investigate the chiral sine-Gordon model using the renormalization group method. The chiral sine-Gordon model is a model for $G$-valued fields and describes a new class of phase transitions, where $G$ is a compact Lie group. We show that the model is renormalizable by means of a perturbation expansion and we derive beta functions of the renormalization group theory. The coefficients of beta functions are represented by the Casimir invariants. The model contains both asymptotically free and ultraviolet strong coupling regions. The beta functions have a zero which is a bifurcation point that divides the parameter space into two regions; they are the weak coupling region and the strong coupling region. A large-$N$ model is also considered. This model is reduced to the conventional sine-Gordon model that describes the Kosterlitz-Thouless transition near the fixed point. In the strong-coupling limit, the model is reduced to a $U(N)$ matrix model.

  9. Chlorophylls, Symmetry, Chirality, and Photosynthesis

    Directory of Open Access Journals (Sweden)

    Mathias O. Senge

    2014-09-01

    Full Text Available Chlorophylls are a fundamental class of tetrapyrroles and function as the central reaction center, accessory and photoprotective pigments in photosynthesis. Their unique individual photochemical properties are a consequence of the tetrapyrrole macrocycle, the structural chemistry and coordination behavior of the phytochlorin system, and specific substituent pattern. They achieve their full potential in solar energy conversion by working in concert in highly complex, supramolecular structures such as the reaction centers and light-harvesting complexes of photobiology. The biochemical function of these structures depends on the controlled interplay of structural and functional principles of the apoprotein and pigment cofactors. Chlorophylls and bacteriochlorophylls are optically active molecules with several chiral centers, which are necessary for their natural biological function and the assembly of their supramolecular complexes. However, in many cases the exact role of chromophore stereochemistry in the biological context is unknown. This review gives an overview of chlorophyll research in terms of basic function, biosynthesis and their functional and structural role in photosynthesis. It highlights aspects of chirality and symmetry of chlorophylls to elicit further interest in their role in nature.

  10. Chiral differential operators and topology

    CERN Document Server

    Cheung, Pokman

    2010-01-01

    The first part of this paper provides a new formulation of chiral differential operators (CDOs) in terms of global geometric quantities. The main result is a recipe to define essentially all sheaves of smooth CDOs on a cs-manifold; its ingredients consist of an affine connection and an even 3-form that trivializes the first Pontrjagin form. With the connection fixed, two suitable 3-forms define isomorphic sheaves of CDOs if and only if their difference is exact. Moreover, conformal structures are in one-to-one correspondence with even 1-forms that trivialize the first Chern form. The second part of this paper concerns the construction of what may be called "chiral Dolbeault complexes". The classical Dolbeault complex of a complex manifold M may be viewed as the functions on an associated cs-manifold with the action of an odd vector field Q that satisfies Q^2=0. Motivated by this, we study the condition under which a conformal sheaf of CDOs on that cs-manifold admits an odd derivation Q' that extends Q and sat...

  11. Chiral transition with magnetic fields

    CERN Document Server

    Ayala, Alejandro; Mizher, Ana Julia; Rojas, Juan Cristobal; Villavicencio, Cristian

    2014-01-01

    We study the nature of the chiral transition for an effective theory with spontaneous breaking of symmetry, where charged bosons and fermions are subject to the effects of a constant external magnetic field. The problem is studied in terms of the relative intensity of the magnetic field with respect to the mass and the temperature. When the former is the smallest of the scales, we present a suitable method to obtain magnetic and thermal corrections up to ring order at high temperature. By these means, we solve the problem of the instability in the boson sector for these theories, where the squared masses, taken as functions of the order parameter, can vanish and even become negative. The solution is found by considering the screening properties of the plasma, encoded in the resummation of the ring diagrams at high temperature. We also study the case where the magnetic field is the intermediate of the three scales and explore the nature of the chiral transition as we vary the field strength, the coupling const...

  12. Retention and chiral recognition mechanism of organo-phosphorus compounds in high-performance liquid chroma-tography

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In normal phase condition, a series of chiral phosphorus organic compounds have been separated by high-performance liquid chromatography. In order to study the retention and chiral recognition mechanism, the method of quantitative structure-enantioselectivity retention relationships (QSERRs) has been investigated from the quantitative equations established between the chromatographic retention of enantiomers and their molecular descriptors of physicochemical properties. The results show that on the Pirkle-type chiral stationary phase (CSP) of Sumichiral OA4700, it is the parameter of LUMO that gives the most contribution to the chromatographic re-tention of O-ethyl O-(substituted) phenyl N-isopropyl phosphoroamidothioates resulting from the interaction of hydrogen bond and (or) p-p interaction. Meanwhile, the chiral recognition is formed from the contribution of logP and LUMO.

  13. SYNTHESIS AND CHARACTERIZATION OF NOVEL CHIRAL SMECTIC C(Sc*) PHASE SHISH-KEBAB TYPE LIQUID CRYSTALLINE BLOCK COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    Shi-jun Zheng; Zi-fa Li; Shu-yuan Zhang; Shao-kui Cao; Ming-sheng Tang; Qiu-jun Fen; Qi-feng Zhou

    1999-01-01

    A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC,DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase when they were heated to their melting temperatures (Tm) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperaturevariable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.

  14. Chiral assembly of achiral pseudoisocyanine with D-and L-phenylalanine

    Institute of Scientific and Technical Information of China (English)

    ZENG LiXi; HE Yujian; DAI ZhiFeng; WANG Jian; WANG CaiQi; YANG YongGang

    2009-01-01

    Supramolecular chirality and molecular self-assembly are important and interesting phenomena in living and non-living systems.In this work,supramolecular chirality of achiral pseudoisocyanine (PIC) J-aggregates was successfully induced by D-,L-phenylalanine (Phe) and other amino acids in NaCI solution.The chiral J-aggregates showed a characteristic,induced circular dichroism (ICD) in the visible region of J-band chromophore which depends on the absolute configuration,concentration and side groups of a-amino acids,as well as temperature.The atomic force microscopy images indicated that the J-aggregates exist in large bundles of entangled nanof ibers,and the observed ICD might result from the macroscopic helical arrangement of the assemblies.

  15. Chiral assembly of achiral pseudoisocyanine with D-and L-phenylalanine

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Supramolecular chirality and molecular self-assembly are important and interesting phenomena in living and non-living systems.In this work,supramolecular chirality of achiral pseudoisocyanine(PIC) J-aggregates was successfully induced by D-,L-phenylalanine(Phe) and other amino acids in NaCl solution.The chiral J-aggregates showed a characteristic,induced circular dichroism(ICD) in the visible region of J-band chromophore which depends on the absolute configuration,concentration and side groups of α-amino acids,as well as temperature.The atomic force microscopy images indicated that the J-aggregates exist in large bundles of entangled nanofibers,and the observed ICD might result from the macroscopic helical arrangement of the assemblies.

  16. Tuning and enhancing enantioselective quenching of calixarene hosts by chiral guest amines.

    Science.gov (United States)

    Lynam, Carol; Jennings, Karen; Nolan, Kieran; Kane, Paddy; McKervey, M Anthony; Diamond, Dermot

    2002-01-01

    The synthesis of a propranolol amide derivative of p-allylcalix[4]arene is described, which has been designed to behave as a molecular sensor capable of distinguishing chiral amines on the basis of their shape and chirality. This molecule can discriminate between the enantiomers of phenylalaninol through the quenching of the fluorescence emission in methanol in contrast to an (S)-dinaphthylprolinol calix[4]arene derivative, which can discriminate between the enantiomers of phenylglycinol, but not phenylalaninol. The separation between the naphthyl fluorophores and the hydrogen-bonding sites within the chiral cavity can be tuned to recognize guest amines with similar separation between aryl groups and hydrogen-bonding sites. The formation of metal ion complexes of the p-allylcalix[4]arene propranolol amide derivative is shown to induce a more regular and rigid cone conformation in the calix[4]arene macrocycle, which generates a significant enhancement in the observed enantiomeric discrimination. PMID:11795818

  17. Separation of rare gases and chiral molecules by selective binding in porous organic cages

    Science.gov (United States)

    Chen, Linjiang; Reiss, Paul S.; Chong, Samantha Y.; Holden, Daniel; Jelfs, Kim E.; Hasell, Tom; Little, Marc A.; Kewley, Adam; Briggs, Michael E.; Stephenson, Andrew; Thomas, K. Mark; Armstrong, Jayne A.; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.; Cooper, Andrew I.

    2014-10-01

    The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation.

  18. Interaction-Induced Chiral Quantum States of the Ultracold Polar Molecules

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-Hao; LIANG Jiu-Qing; MA Jie; CHEN Gang; JIA Suo-Tang

    2012-01-01

    The ultracold polar molecules with the tunable dipole-dipole interaction, not only would enable explorations of a large class of exotic many-body physics phenomena, but also could be used for quantum information processing. In the present paper we demonstrate that this dipole-dipole interaction can generate the degenerate chiral quantum states acting as a qubit robust against noise when the ultracold polar molecules are confined by a triangular lattice. Moreover, we also find two first-order quantum phase transitions by controlling an external driving t~eld. One is the transition with the change of the different degenerate chiral quantum states. The other is the transition with the breaking of the degenerate quantum chirAL states to the nondegenerate state. In experiment, these first-order quantum phase transitions can be detected by measuring the collective molecular population.

  19. Enabling Light Work in Helical Self-Assembly for Dynamic Amplification of Chirality with Photoreversibility.

    Science.gov (United States)

    Cai, Yunsong; Guo, Zhiqian; Chen, Jianmei; Li, Wenlong; Zhong, Liubiao; Gao, Ya; Jiang, Lin; Chi, Lifeng; Tian, He; Zhu, Wei-Hong

    2016-02-24

    Light-driven transcription and replication are always subordinate to a delicate chirality transfer. Enabling light work in construction of the helical self-assembly with reversible chiral transformation becomes attractive. Herein we demonstrate that a helical hydrogen-bonded self-assembly is reversibly photoswitched between photochromic open and closed forms upon irradiation with alternative UV and visible light, in which molecular chirality is amplified with the formation of helixes at supramolecular level. The characteristics in these superhelixes such as left-handed or right-handed twist and helical length, height, and pitch are revealed by SEM and AFM. The helical photoswitchable nanostructure provides an easily accessible route to an unprecedented photoreversible modulation in morphology, fluorescence, and helicity, with precise assembly/disassembly architectures similar to biological systems such as protein and DNA. PMID:26709946

  20. Atroposelective Synthesis of Axially Chiral Thiohydantoin Derivatives.

    Science.gov (United States)

    Sarigul, Sevgi; Dogan, Ilknur

    2016-07-15

    Nonracemic axially chiral thiohydantoins were synthesized atroposelectively by the reaction of o-aryl isothiocyanates with amino acid ester salts in the presence of triethylamine (TEA). The synthesis of the nonaxially chiral derivatives, however, gave thiohydantoins racemized at C-5 of the heterocyclic ring. The micropreparatively resolved enantiomers of the nonaxially chiral derivatives from the racemic products were found to be optically stable under neutral conditions. On formation of the 5-methyl-3-arylthiohydantoin ring, bulky o-aryl substituents at N3 were found to suppress the C-5 racemization and in this way enabled the transfer of chirality from the α-amino acid to the products. The corresponding 5-isopropylthiohydantoins turned out to be more prone to racemization at C-5 during the ring formation. The isomer compositions of the synthesized axially chiral thiohydantoins have been determined through HPLC analyses with chiral stationary phases. In most cases a high prevalence of the P isomers over the M isomers has been obtained. The barriers to rotation determined around the Nsp(2)-Caryl chiral axis were found to be dependent upon the size of the o-halo aryl substituents. PMID:27322739

  1. Spontaneous Planar Chiral Symmetry Breaking in Cells

    Science.gov (United States)

    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.

  2. Chiral Structure of Baryon and Scalar Tetraquark Currents

    Directory of Open Access Journals (Sweden)

    Chen Hua-Xing

    2014-03-01

    Full Text Available We investigate chiral properties of local fields of baryons consisting of three quarks with flavor SU(3 symmetry. We construct explicitly independent local threequark fields belonging to definite Lorentz and flavor representations. We discuss some implications of the allowed chiral symmetry representations on physical quantities such as axial coupling constants and chiral invariant Lagrangians. We also systematically investigate chiral properties of local scalar tetraquark currents, and study their chiral transformation properties.

  3. Cold prebiotic evolution, tunneling, chirality and exobiology

    Energy Technology Data Exchange (ETDEWEB)

    Goldanskii, V.I. [N.N. Semenov Institute of Chemical Physics Russian Academy of Sciences UL.Kosygina 4, 117334 Moscow (Russia)

    1996-07-01

    The extra-terrestrial scenario of the origin of life suggested by Svante Arrhenius (1) as the {open_quote}panspermia{close_quote} hypothesis was revived by the discovery of a low-temperature quantum limit of a chemical reaction rate caused by the molecular tunneling (2). Entropy factors play no role near absolute zero, and slow molecular tunneling can lead to the exothermic formation of quite complex molecules. Interstellar grains or particles of cometary tails could serve as possible cold seeds of life, with acetic acid, urea and products of their polycondensation as quasi-equilibrium intermediates. Very cold solid environment hinders racemization and stabilizes optical activity under conditions typical for outer space. Neither {open_quote}advantage{close_quote} factors can secure the evolutionary formation of chiral purity of initial prebiotic monomeric medium{emdash}even being temporary achieved it cannot be maintained at subsequent stages of prebiotic evolution because of counteraction of {open_quote}enantioselective pressure{close_quote}. Only bifurcational mechanism of the formation of prebiotic homochiral{emdash}monomeric and afterwards polymeric{emdash}medium and its subsequent transformation in {open_quote}homochiral chemical automata{close_quote} ({open_quote}biological big bang{close_quote}{emdash}passage from {open_quote}stochastic{close_quote} to {open_quote}algorithmic{close_quote} chemistry) is possible and can be realized. Extra-terrestrial (cold, solid phase) scenarios of the origin of life seem to be more promising from that point of view than terrestrial (warm) scenarios. Within a scheme of five main stages of prebiological evolution some problems important for further investigation are briefly discussed. {copyright} {ital 1996 American Institute of Physics.}

  4. Synthesis of homochiral tris-indanyl molecular rods

    DEFF Research Database (Denmark)

    Kjeldsen, Niels Due; Funder, Erik Daa; Gothelf, Kurt Vesterager

    2014-01-01

    Homochiral tris-indanyl molecular rods designed for supramolecular surface self-assembly were synthesized. The chiral indanol moiety was constructed via a Ti-mediated alkyne trimerization. Further manipulations resulted in a homochiral indanol monomer. This was employed as the precursor...... for successive Sonogashira and Ohira-Bestman reactions towards the homochiral tris-indanyl molecular rods. The molecular rods will be applied for scanning tunnelling microscopy studies of their surface self-assembly and chirality....

  5. Enantiomeric excesses of chiral amines in ammonia-rich carbonaceous meteorites

    Science.gov (United States)

    Pizzarello, Sandra; Yarnes, Christopher T.

    2016-06-01

    Chiral homogeneity is essential to the structure and function of terrestrial biopolymers but the origin of this "homochirality" is poorly understood and remains one of the many unknowns surrounding the origins of life. Several amino acids extracted from Carbonaceous Chondrite meteorites display L-enantiomeric excesses (ee) and their findings have encouraged suggestions that an input of non-racemic meteoritic compounds to early Earth might have led to terrestrial homochirality. Motivated by occasional indications of possible ee in other classes of soluble meteoritic compounds, we have undertaken a systematic study of the chiral distribution of amines in Renazzo-type (CR) meteorites, where they are the second most abundant organic molecular species and ammonia is by far the most abundant single molecule. We report here the first time finding of L-ee for two chiral amines in several pristine CR meteorites from Antarctica and outline a proposal by which the compounds possibly formed from the same ketone precursors as some of the chiral amino acids. This would occur during a warm hydrous stage of the asteroidal parent body, via a reductive amination process in the presence of a large abundance of ammonia, where the precursors' adsorption upon mineral phases possessing asymmetry offered the opportunity for chiral induction. Because the precursor ketones are achiral, the proposal underscores the likelihood of diverse asymmetric influences and processes in cosmochemistry.

  6. A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER)

    Science.gov (United States)

    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.

  7. Ferrimagnetism and abnormal spin-lattice coupling in dilute magnetic ferroelectric (Bi0.46Na0.46Ba0.08)TiO3:Co

    Institute of Scientific and Technical Information of China (English)

    Fan Jing; Dong Xin-Wei; Song You; Wang Ke-Feng; Liu Jun-Ming; Jiang Xiang-Ping

    2011-01-01

    We have investigated the low-temperature magnetism and spin-lattice coupling in (Bi0.46Na0.46Ba0.08)TiO3:Co in order to understand the magnetoelectric effect in such artificially synthesized dilute magnetic ferroelectrics. It is revealed that the as-prepared (Bi0.46Na0.46Ba0.08)TiO3:Co at Co content of 20%~30% exhibits fascinating ferrimagnetism which is robust against magnetic field, the abnormal spin-lattice coupling characterized by a negative magnetostriction effect; and the suppressed magnetic moment within the temperature range of 30 K~50 K is identified. These magnetic behaviours at low temperatures can be explained by the competition between the ferrimagnetic response and the magnetic moment suppression induced by the abnormal spin-lattice coupling effect. Finally, the ferroelectric and magnetodielectric properties are also discussed.

  8. Preface to the Surface Science Topical Issue on Chirality at Surfaces

    Science.gov (United States)

    2014-11-01

    This Topical Issue of Surface Science focuses on the rapidly growing interest in the structure and enantioselective properties of chiral surfaces and chiral organic layers on surfaces. Chirality has intrigued scientists since the time of Pasteur and his 1848 [1] demonstration of the relationship between the optical rotation of light and the atomic structure of the compounds through which it propagates. The origin of optical rotation in the structure of organic molecules and the tetrahedral nature of the carbon atom was first appreciated and articulated by van't Hoff in 1874 [2]. In biochemistry, the importance of molecular chirality arises from the fact that most naturally occurring chiral biomolecules exist in homochiral form. For example, the fundamental building blocks of proteins are the amino acids which all appear in the L-enantiomeric form in nature. The implications of biomolecular homochirality were not truly appreciated until the late 1950s [3] when the stereochemistry of the artificially produced drug thalidomide was implicated in the physical defects observed in thousands of children born to mothers who had used the drug during pregnancy. This then sparked an explosion in asymmetric synthesis and enantioselective chemical processing in general, as regulations required that chiral pharmaceuticals be manufactured in enantiomerically pure form. The development of heterogenous catalysts for industrial-scale production of enantiomerically pure molecules is still a huge challenge. Many of the studies in this Topical Issue are aimed at developing a molecular level understanding of the surface processes which direct enantioselective reactions at gas-solid and liquid-solid interfaces.

  9. Interplay between Deconfinement and Chiral Properties

    CERN Document Server

    Suganuma, Hideo; Redlich, Krzysztof; Sasaki, Chihiro

    2016-01-01

    We study interplay between confinement/deconfinement and chiral properties. We derive some analytical relations of the Dirac modes with the confinement quantities, such as the Polyakov loop, its susceptibility and the string tension. For the confinement quantities, the low-lying Dirac eigenmodes are found to give negligible contribution, while they are essential for chiral symmetry breaking. This indicates no direct, one-to-one correspondence between confinement/deconfinement and chiral properties in QCD. We also investigate the Polyakov loop in terms of the eigenmodes of the Wilson, the clover and the domain-wall fermion kernels, respectively.

  10. Enhanced Chiral Recognition by Cyclodextrin Dimers

    Directory of Open Access Journals (Sweden)

    Bart Jan Ravoo

    2011-07-01

    Full Text Available 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.

  11. Effective action in general chiral superfield model

    OpenAIRE

    Petrov, A. Yu.

    2000-01-01

    The effective action in general chiral superfield model with arbitrary k\\"{a}hlerian potential $K(\\bar{\\Phi},\\Phi)$ and chiral (holomorphic) potential $W(\\Phi)$ is considered. The one-loop and two-loop contributions to k\\"{a}hlerian effective potential and two-loop (first non-zero) contribution to chiral effective potential are found for arbitrary form of functions $K(\\bar{\\Phi},\\Phi)$ and $W(\\Phi)$. It is found that despite the theory is non-renormalizable in general case two-loop contributi...

  12. The convoluted evolution of snail chirality

    Science.gov (United States)

    Schilthuizen, M.; Davison, A.

    2005-11-01

    The direction that a snail (Mollusca: Gastropoda) coils, whether dextral (right-handed) or sinistral (left-handed), originates in early development but is most easily observed in the shell form of the adult. Here, we review recent progress in understanding snail chirality from genetic, developmental and ecological perspectives. In the few species that have been characterized, chirality is determined by a single genetic locus with delayed inheritance, which means that the genotype is expressed in the mother's offspring. Although research lags behind the studies of asymmetry in the mouse and nematode, attempts to isolate the loci involved in snail chirality have begun, with the final aim of understanding how the axis of left-right asymmetry is established. In nature, most snail taxa (>90%) are dextral, but sinistrality is known from mutant individuals, populations within dextral species, entirely sinistral species, genera and even families. Ordinarily, it is expected that strong frequency-dependent selection should act against the establishment of new chiral types because the chiral minority have difficulty finding a suitable mating partner (their genitalia are on the ‘wrong’ side). Mixed populations should therefore not persist. Intriguingly, however, a very few land snail species, notably the subgenus Amphidromus sensu stricto, not only appear to mate randomly between different chiral types, but also have a stable, within-population chiral dimorphism, which suggests the involvement of a balancing factor. At the other end of the spectrum, in many species, different chiral types are unable to mate and so could be reproductively isolated from one another. However, while empirical data, models and simulations have indicated that chiral reversal must sometimes occur, it is rarely likely to lead to so-called ‘single-gene’ speciation. Nevertheless, chiral reversal could still be a contributing factor to speciation (or to divergence after speciation) when

  13. The Macromolecular Route to Chiral Amplification.

    Science.gov (United States)

    Green; Park; Sato; Teramoto; Lifson; Selinger; Selinger

    1999-11-01

    Cooperative phenomena, described by one-dimensional statistical physical methods, are observed between the enantiomeric characteristics of monomeric materials and the polymers they produce. The effect of minute energies associated with this amplified chirality, although currently not interpretable, can be easily measured. Nonlinear relationships between enantiomeric excess or enantiomeric content and polymer properties may offer the possibility of developing chiral catalysts and chiral chromatographic materials in which the burden of large enantiomeric excess or content may be considerably alleviated. New approaches to information and sensor technology may become possible. PMID:10556885

  14. Synthesis of chiral dopants based on carbohydrates.

    Science.gov (United States)

    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.

  15. Chiral particle separation by a non-chiral micro-lattice

    OpenAIRE

    Bogunovic, Lukas; Fliedner, Marc; Eichhorn, Ralf; Wegener, Sonja; Regtmeier, Jan; Anselmetti, Dario; Reimann, Peter

    2012-01-01

    We conceived a model experiment for a continuous separation strategy of chiral molecules (enantiomers) without the need of any chiral selector structure or derivatization agents: Micro-particles that only differ by their chirality are shown to migrate along different directions when driven by a steady fluid flow through a square lattice of cylindrical posts. In accordance with our numerical predictions, the transport directions of the enantiomers depend very sensitively on the orientation of ...

  16. Enhanced sensing of molecular optical activity with plasmonic nanohole arrays

    CERN Document Server

    Gorkunov, Maxim V; Kondratov, Alexey V

    2016-01-01

    Prospects of using metal hole arrays for the enhanced optical detection of molecular chirality in nanosize volumes are investigated. Light transmission through the holes filled with an optically active material is modeled and the activity enhancement by more than an order of magnitude is demonstrated. The spatial resolution of the chirality detection is shown to be of a few tens of nanometers. From comparing the effect in arrays of cylindrical holes and holes of complex chiral shape, it is concluded that the detection sensitivity is determined by the plasmonic near field enhancement. The intrinsic chirality of the arrays due to their shape appears to be less important.

  17. Enhanced magnetic resonance imaging and staining of cancer cells using ferrimagnetic H-ferritin nanoparticles with increasing core size

    Directory of Open Access Journals (Sweden)

    Cai Y

    2015-04-01

    Full Text Available Yao Cai,1–3 Changqian Cao,1,2 Xiaoqing He,1 Caiyun Yang,1–3 Lanxiang Tian,1,2 Rixiang Zhu,2 Yongxin Pan1,21France–China Bio-Mineralization and Nano-Structures Laboratory, 2Paleomagnetism and Geochronology Laboratory, Key Laboratory of the Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, 3University of Chinese Academy of Sciences, Beijing, People’s Republic of ChinaPurpose: This study is to demonstrate the nanoscale size effect of ferrimagnetic H-ferritin (M-HFn nanoparticles on magnetic properties, relaxivity, enzyme mimetic activities, and application in magnetic resonance imaging (MRI and immunohistochemical staining of cancer cells.Materials and methods: M-HFn nanoparticles with different sizes of magnetite cores in the range of 2.7–5.3 nm were synthesized through loading different amounts of iron into recombinant human H chain ferritin (HFn shells. Core size, crystallinity, and magnetic properties of those M-HFn nanoparticles were analyzed by transmission electron microscope and low-temperature magnetic measurements. The MDA-MB-231 cancer cells were incubated with synthesized M-HFn nanoparticles for 24 hours in Dulbecco’s Modified Eagle’s Medium. In vitro MRI of cell pellets after M-HFn labeling was performed at 7 T. Iron uptake of cells was analyzed by Prussian blue staining and inductively coupled plasma mass spectrometry. Immunohistochemical staining by using the peroxidase-like activity of M-HFn nanoparticles was carried out on MDA-MB-231 tumor tissue paraffin sections.Results: The saturation magnetization (Ms, relaxivity, and peroxidase-like activity of synthesized M-HFn nanoparticles were monotonously increased with the size of ferrimagnetic cores. The M-HFn nanoparticles with the largest core size of 5.3 nm exhibit the strongest saturation magnetization, the highest peroxidase activity in immunohistochemical staining, and the highest r2 of 321 mM-1 s-1, allowing to

  18. New Chiral Metal Cluster Systems for Catalytic Asymmetric Syntheses of Chiral Alcohols

    Institute of Scientific and Technical Information of China (English)

    LI Yan-yun; CHEN Jian-shan; YANG Chuan-bo; DONG Zhen-rong; LI Bao-zhu; ZHANG Hui; GAO Jing-xing; TAKAO Ikariya

    2004-01-01

    The efficient chiral Ru3(CO)12 systems were prepared in situ from Ru3(CO)12 and various chiral diiminoor diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu3(CO)11]- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru3 framework.

  19. Double chiral logarithms of Generalized Chiral Perturbation Theory for low-energy pi-pi scattering

    OpenAIRE

    L. GirlandaPadua U. & INFN

    2015-01-01

    We express the two-massless-flavor Gell-Mann--Oakes--Renner ratio in terms of low-energy pi-pi observables, including the O(p^6) double chiral logarithms of generalized chiral perturbation theory. Their contribution is sizeable and tends to compensate the one from the single chiral logarithms. However it is not large enough to spoil the convergence of the chiral expansion. As a signal of reduced theoretical uncertainty, we find that the scale dependence from the one-loop single logarithms is ...

  20. Design and Synthesis of Novel Molecular Tweezers Derived from Chenodeoxycholic Acid

    Institute of Scientific and Technical Information of China (English)

    Zhi Gang ZHAO; Qi Ming MU; Shu Hua CHEN

    2004-01-01

    A novel type of chiral molecular tweezers has been designed and synthesized by using chenodeoxy cholic acid as spacer and the aromatic compounds as arm. Their structures were characterized by 1HNMR, IR, MS spectra and elemental analysis. These chiral molecular tweezers showed good enantioselectivity for D-amino acid methyl esters.

  1. Ferrimagnetism and magnetic phase separation in Nd1−xYxMnO3 studied by magnetization and high frequency electron paramagnetic resonance

    International Nuclear Information System (INIS)

    Ferrimagnetism and metamagnetic features tunable by composition are observed in the magnetic response of Nd1−xYxMnO3, for x=0.1–0.5. For all values of x in the series, the compound crystallizes in orthorhombic Pbnm space group similar to NdMnO3. Magnetization studies reveal a phase transition of the Mn-sublattice below TNMn≈80K for all compositions, which, decreases up on diluting the Nd-site with Yttrium. For x=0.35, ferrimagnetism is observed. At 5 K, metamagnetic transition is observed for all compositions x<0.4. The evolution of magnetic ground states and appearance of ferrimagnetism in Nd1−xYxMnO3 can be accounted for by invoking the scenario of magnetic phase separation. The high frequency electron paramagnetic resonance measurements on x=0.4 sample, which is close to the critical composition for phase separation, revealed complex temperature dependent lineshapes clearly supporting the assumption of magnetic phase separation

  2. The preparation and high-frequency electromagnetic properties of ferrimagnetic bisphthalonitrile–Fe3O4 core–shell hollow microspheres

    International Nuclear Information System (INIS)

    A novel kind of ferrimagnetic core–shell hollow microsphere was prepared by a two-step solvothermal method with bisphthalonitrile and FeCl3. Scanning electron microscope and transmission electron microscope images show that the diameter of hollow microsphere is about 320 nm and the hollow microspheres are made of small Fe3O4 nanoparticles. Compared with traditional pure Fe3O4 nanoparticles, the hollow microspheres exhibited very strong magnetism due to their special structures. The saturation magnetization and coercivity of the ferrimagnetic hollow microspheres were 103.9 emu g−1 and 161.6 Oe, respectively. The electromagnetic properties of hybrids showed cooperative nonlinear magnetic and dielectric resonance in Ku-band. Moreover, the hybrid hollow microspheres also showed electromagnetic shielding characteristics in Ku-band. Three nesting reflection loss peaks can be seen around 13.0, 16.0 and 17.3 GHz. A minimum reflection loss of −38.5 dB was reached at 17.3 GHz with an absorber thickness of 4.2 mm. - Highlights: • A novel kind of ferrimagnetic core–shell hollow microspheres was prepared. • The core–shell microspheres showed strong magnetism. • The sample showed cooperative nonlinear magnetic resonance in Ku-band. • The microspheres showed absorption properties only in Ku-band

  3. Chiral exceptional points in metasurfaces

    Science.gov (United States)

    Kang, Ming; Chen, Jing; Chong, Y. D.

    2016-09-01

    An exceptional point (EP) is a degeneracy occurring in a non-energy-conserving system, in which two eigenvectors of a non-Hermitian Hamiltonian coalesce. We explore how EPs can be realized in a metamaterial surface, or metasurface, consisting of a pair of lossy coupled linear antennas in each unit cell. EPs appear in the eigenvectors of the transmission matrix by tuning the frequency and the coupling and loss rates of the metasurface. Each EP is associated with the appearance of a circularly polarized transmission eigenstate; hence, within the parameter space of the system, the EPs lie along pairs of curves with distinct chirality. Our results are obtained using finite-difference time-domain simulations, as well as a fitted coupled-mode theory. The coupled-mode theory agrees well with the numerical results and is capable of accurately predicting the EP f curves.

  4. Resolution of the Chiral Drugs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral drugs are generally not permitted to be used in racemic form so that unintended side effects and unnecessary environmental hazards are avoided. Moreover, homochiral molecules are required immediately to progress key toxicological and clinical studies in the drug discovery. One series of technologies which can rapidly supply homochiral compounds is the separation of racemates, and of those the technique of crystallization of diastereomers is extremely effective-principally because it is simple to operate and it affords both enantiomers. In classical resolution via diastereoisomeric salt formation, the resolved compounds are limited to a given racemic acid or base and the choice of a suitable resolving agent for a racemic target compound is achieved by time-consuming trial-and-error procedure.

  5. Resolution of the Chiral Drugs

    Institute of Scientific and Technical Information of China (English)

    DENG; JinGen

    2001-01-01

    Chiral drugs are generally not permitted to be used in racemic form so that unintended side effects and unnecessary environmental hazards are avoided. Moreover, homochiral molecules are required immediately to progress key toxicological and clinical studies in the drug discovery. One series of technologies which can rapidly supply homochiral compounds is the separation of racemates, and of those the technique of crystallization of diastereomers is extremely effective-principally because it is simple to operate and it affords both enantiomers. In classical resolution via diastereoisomeric salt formation, the resolved compounds are limited to a given racemic acid or base and the choice of a suitable resolving agent for a racemic target compound is achieved by time-consuming trial-and-error procedure.  ……

  6. Chiral magnetic effect and holography

    Energy Technology Data Exchange (ETDEWEB)

    Kirsch, Ingo; Kalaydzhyan, Tigran

    2013-01-15

    The chiral magnetic effect (CME) is a highly discussed effect in heavy-ion collisions stating that, in the presence of a magnetic field B, an electric current is generated in the background of topologically nontrivial gluon fields. We present a holographic (AdS/CFT) description of the CME in terms of a fluid-gravity model which is dual to a strongly-coupled plasma with multiple anomalous U(1) currents. In the case of two U(1) charges, one axial and one vector, the CME formally appears as a first-order transport coefficient in the vector current. We will holographically compute this coefficient at strong coupling and compare it with the hydrodynamic result. Finally, we will discuss an anisotropic variant of the model and study a possible dependence of the CME on the elliptic flow coefficient {nu}{sub 2}.

  7. Chiral Lagrangians and proton decay

    International Nuclear Information System (INIS)

    The phenomenological Lagrangian method is employed to obtain nucleon decay branching ratio sin conventional and supersymmetric Grand Unified Theories. After a brief survey of the theory of nucleon decay, the dominant effective baryon-number violating operators in supergravity models are derived where the observed sector is described by an SU(5) SUSY GUT. It is shown how the phenomenological Lagrangian technique may be understood from a mathematical viewpoint. This technique is then applied to calculate two- and three-body nucleon decay branching ratios in SUGRA models. Finally, the author answers criticism of the usual phenomenological Lagrangian approach when used for nucleon decay calculations by developing a hybrid chiral quark model. With this model, branching ratios for conventional and SUSY GUTs are calculated. (author)

  8. Chiral supergravity actions and superforms

    CERN Document Server

    Gates, S J; Tartaglino-Mazzucchelli, G

    2009-01-01

    The superform construction of supergravity actions, christened the "ectoplasm method," is based on the use of a closed super d-form in the case of d space-time dimensions. In known examples, such superforms are obtained by iteratively solving nontrivial cohomological problems. The latter usually makes this scheme no less laborious than the normal coordinate method for deriving component actions for matter-coupled supergravity. In this note we present an alternative procedure to generate required superforms in four space-time dimensions, which makes use of self-dual vector multiplets. It provides the shortest derivation of chiral actions in two different theories: (i) N = 1 old minimal supergravity; and (ii) N = 2 conformal supergravity. The N = 2 superform construction is developed here for the first time. Although our consideration is restricted to the case of four dimensions, a generalization to higher dimensions is plausible.

  9. Antisymmetric Couplings Enable Direct Observation of Chirality in Nuclear Magnetic Resonance Spectroscopy

    CERN Document Server

    King, Jonathan P; Blanchard, John W

    2016-01-01

    Here we demonstrate that a term in the nuclear spin Hamiltonian, the antisymmetric \\textit{J}-coupling, is fundamentally connected to molecular chirality. We propose and simulate a nuclear magnetic resonance (NMR) experiment to observe this interaction and differentiate between enantiomers without adding any additional chiral agent to the sample. The antisymmetric \\textit{J}-coupling may be observed in the presence of molecular orientation by an external electric field. The opposite parity of the antisymmetric coupling tensor and the molecular electric dipole moment yields a sign change of the observed coupling between enantiomers. We show how this sign change influences the phase of the NMR spectrum and may be used to discriminate between enantiomers.

  10. Chiral Asymmetric Structures in Aspartic Acid and Valine Crystals Assessed by Atomic Force Microscopy.

    Science.gov (United States)

    Teschke, Omar; Soares, David Mendez

    2016-03-29

    Structures of crystallized deposits formed by the molecular self-assembly of aspartic acid and valine on silicon substrates were imaged by atomic force microscopy. Images of d- and l-aspartic acid crystal surfaces showing extended molecularly flat sheets or regions separated by single molecule thick steps are presented. Distinct orientation surfaces were imaged, which, combined with the single molecule step size, defines the geometry of the crystal. However, single molecule step growth also reveals the crystal chirality, i.e., growth orientations. The imaged ordered lattice of aspartic acid (asp) and valine (val) mostly revealed periodicities corresponding to bulk terminations, but a previously unreported molecular hexagonal lattice configuration was observed for both l-asp and l-val but not for d-asp or d-val. Atomic force microscopy can then be used to identify the different chiral forms of aspartic acid and valine crystals.

  11. Design, synthesis, and self-assembly of optically active perylenetetracarboxylic diimide bearing two peripheral chiral binaphthyl moieties

    International Nuclear Information System (INIS)

    An optically active perylenetetracarboxylic diimide (PTCDI) bearing two optically active binaphthyl moieties has been designed and synthesized. The self-assembly properties of these novel PTCDI derivatives in DMF/H2O were systematically investigated by electronic absorption, circular dichroism (CD) spectra, IR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) technique. Observation of CD signal in the whole absorption region of PTCDI chromophore, indicates effective chiral information transfer from the chiral binaphthyl units to the central PTCDI chromophore at molecular level. The intermolecular π–π interaction between PTCDI rings together with the additionally formed hydrogen bonds between the crown ether moieties of (S)-1 and additional water molecules and the chiral discrimination of periphery chiral side chains induces further intensified asymmetrical perturbation of the chiral binaphthyl units to the central PTCDI chromophore during the self-assembly process, resulting in the formation of right-handed helical arrangement of corresponding molecules in a stack of PTCDI chromophores in aggregates. In addition, the formed nanostructures were revealed to show good semiconducting properties. - Graphical abstract: An optically active perylenetetracarboxylic diimide bearing two optically active binaphthyl moieties has been prepared. Self-assembly properties of this novel PTCDI derivative in DMF/H2O were systematically investigated. Experimental results indicate the effective chiral information transfer and expression at molecular and intermolecular level. Highlights: ► An optically active perylenetetracarboxylic diimide bearing two optically active binaphthyl moieties has been prepared. ► Self-assembly properties of this novel PTCDI derivative in DMF/H2O were systematically investigated. ► Experimental results indicate the effective chiral information transfer and expression at molecular

  12. New Advances in Chiral Catalyst Immobilization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Asymmetric catalysis of organic reactions is one of the most efficient ways to obtain optically pure chiral compounds, which are crucially important to the development of modern pharmaceutical and fine chemical industries, as well as material science.

  13. Personal recollections on chiral symmetry breaking

    Science.gov (United States)

    Kobayashi, Makoto

    2016-07-01

    The author's work on the mass of pseudoscalar mesons is briefly reviewed. The emergence of the study of CP violation in the renormalizable gauge theory from consideration of chiral symmetry in the quark model is discussed.

  14. Chirality and angular momentum in optical radiation

    CERN Document Server

    Coles, Matt M

    2012-01-01

    This paper develops, in precise quantum electrodynamic terms, photonic attributes of the "optical chirality density", one of several measures long known to be conserved quantities for a vacuum electromagnetic field. The analysis lends insights into some recent interpretations of chiroptical experiments, in which this measure, and an associated chirality flux, have been treated as representing physically distinctive "superchiral" phenomena. In the fully quantized formalism the chirality density is promoted to operator status, whose exploration with reference to an arbitrary polarization basis reveals relationships to optical angular momentum and helicity operators. Analyzing multi-mode beams with complex wave-front structures, notably Laguerre-Gaussian modes, affords a deeper understanding of the interplay between optical chirality and optical angular momentum. By developing theory with due cognizance of the photonic character of light, it emerges that only the spin angular momentum of light is engaged in such...

  15. Staggered Heavy Baryon Chiral Perturbation Theory

    CERN Document Server

    Bailey, Jon A

    2007-01-01

    Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms the order of the cubed pion mass, which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms the order of the squared lattice spacing. The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in d...

  16. NN Interaction in Chiral Constituent Quark Models

    CERN Document Server

    Valcarce, A; González, P

    2003-01-01

    We review the actual state in the description of the NN interaction by means of chiral constituent quark models. We present a series of relevant features that are nicely explained within the quark model framework.

  17. Chiral Magnetic Effect in Heavy Ion Collisions

    CERN Document Server

    Liao, Jinfeng

    2016-01-01

    The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. It is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields $|\\vec{\\bf B}|\\sim m_\\pi^2$ are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. In this contribution we give a brief overview on the status of such efforts.

  18. Chiral Schwinger model at finite temperature

    International Nuclear Information System (INIS)

    We discuss the chiral Schwinger model at finite temperature using Fujikawa's method. We solve this model exactly and show that the axial anomaly and the dynamically generated mass for the gauge field are temperature independent. (author). 20 refs

  19. Nuclear Chiral EFT in the Precision Era

    CERN Document Server

    Epelbaum, Evgeny

    2015-01-01

    Chiral effective field theory has established itself as the method of choice to study nuclear forces and low-energy nuclear dynamics. I review the status and prospects of this approach and discuss ongoing efforts to advance the precision frontier for ab initio description of few-nucleon systems. Special emphasis is put on the precise determination of the two-nucleon force at fifth order in the chiral expansion, role of the chiral symmetry, the convergence pattern of the chiral expansion and the quantification of the theoretical uncertainties. The discussed topics are essential for ongoing studies towards elucidating the structure of the three-nucleon force which will be briefly addressed as well.

  20. Chiral susceptibility and the scalar Ward identity.

    Energy Technology Data Exchange (ETDEWEB)

    Chang, L.; Liu, Y.-X.; Roberts, C. D.; Shi, Y.-M.; Sun, W.-M.; Zong, H.-S.; Physics; Inst. of Applied Physics and Computational Mathematics; Peking Univ.; National Lab. of Heavy Ion Accelerator; Univ. of New South Wales; Nanjing Univ.; Joint Center for Particle, Nuclear Physics and Cosmology

    2009-03-01

    The chiral susceptibility is given by the scalar vacuum polarization at zero total momentum. This follows directly from the expression for the vacuum quark condensate so long as a nonperturbative symmetry preserving truncation scheme is employed. For QCD in-vacuum the susceptibility can rigorously be defined via a Pauli-Villars regularization procedure. Owing to the scalar Ward identity, irrespective of the form or Ansatz for the kernel of the gap equation, the consistent scalar vertex at zero total momentum can automatically be obtained and hence the consistent susceptibility. This enables calculation of the chiral susceptibility for markedly different vertex Ansaetze. For the two cases considered, the results were consistent and the minor quantitative differences easily understood. The susceptibility can be used to demarcate the domain of coupling strength within a theory upon which chiral symmetry is dynamically broken. Degenerate massless scalar and pseudoscalar bound-states appear at the critical coupling for dynamical chiral symmetry breaking.

  1. Insights on some chiral smectic phases

    Indian Academy of Sciences (India)

    B Pansu

    2003-08-01

    Combining layered positional order as smectic order and chirality can generate complex architectures since twist parallel to the layers is not allowed. This paper will review some new experimental results on different phases resulting from the competition between smectic positional order and twist orientational order. It concerns the TGBA and the NL*, that is the liquid line phase as well as the SmQ phase. Chiral effects in the isotropic phase will also be discussed.

  2. Lattice quantum chromodynamics with approximately chiral fermions

    Energy Technology Data Exchange (ETDEWEB)

    Hierl, Dieter

    2008-05-15

    In this work we present Lattice QCD results obtained by approximately chiral fermions. We use the CI fermions in the quenched approximation to investigate the excited baryon spectrum and to search for the {theta}{sup +} pentaquark on the lattice. Furthermore we developed an algorithm for dynamical simulations using the FP action. Using FP fermions we calculate some LECs of chiral perturbation theory applying the epsilon expansion. (orig.)

  3. Is the chiral U(1) theory trivial?

    International Nuclear Information System (INIS)

    The chiral U(1) theory differs from the corresponding vector theory by an imaginary contribution to the effective action which amounts to a phase factor in the partition function. The vector theory, i.e. QED, is known to be trivial in the continuum limit. It is argued that the presence of the phase factor will not alter this result and the chiral theory is non-interacting as well. (orig.)

  4. Attomolar DNA detection with chiral nanorod assemblies

    OpenAIRE

    Ma, Wei; Kuang, Hua; Xu, Liguang; Ding, Li; Xu, Chuanlai; Wang, Libing; Kotov, Nicholas A.

    2013-01-01

    Nanoscale plasmonic assemblies display exceptionally strong chiral optical activity. So far, their structural design was primarily driven by challenges related to metamaterials whose practical applications are remote. Here we demonstrate that gold nanorods assembled by the polymerase chain reaction into DNA-bridged chiral systems have promising analytical applications. The chiroplasmonic activity of side-by-side assembled patterns is attributed to a 7–9 degree twist between the nanorod axes. ...

  5. Chiral Symmetry in algebraic and analytic approaches

    OpenAIRE

    Vereshagin, V.; Dillig, M.; Vereshagin, A.

    1996-01-01

    We compare among themselves two different methods for the derivation of results following from the requirement of polynomial boundedness of tree-level chiral amplitudes. It is shown that the results of the algebraic approach are valid also in the framework of the analytical one. This means that the system of Sum Rules and Bootstrap equations previously obtained with the help of the latter approach can be analyzed in terms of reducible representations of the unbroken Chiral group with the know...

  6. Super Virasoro Algebras From Chiral Supergravity

    CERN Document Server

    Hyakutake, Yoshifumi

    2015-01-01

    In this note, we construct Noether charges for the chiral supergravity, which contains the Lorentz Chern-Simons term, by applying Wald's prescription to the vielbein formalism. We investigate the AdS3/CFT2 correspondence by using the vielbein formalism. The asymptotic symmetry group is carefully examined by taking into account the local Lorentz transformation, and we construct super Virasoro algebras with central extensions from the chiral supergravity.

  7. Proton Spin Based On Chiral Dynamics

    OpenAIRE

    Weber, H. J.

    1999-01-01

    Chiral spin fraction models agree with the proton spin data only when the chiral quark-Goldstone boson couplings are pure spinflip. For axial-vector coupling from soft-pion physics this is true for massless quarks but not for constituent quarks. Axial-vector quark-Goldstone boson couplings with {\\bf constituent} quarks are found to be inconsistent with the proton spin data.

  8. Chiral effective model with the Polyakov loop

    OpenAIRE

    Fukushima, Kenji

    2003-01-01

    We discuss how the simultaneous crossovers of deconfinement and chiral restoration can be realized. We propose a dynamical mechanism assuming that the effective potential gives a finite value of the chiral condensate if the Polyakov loop vanishes. Using a simple model, we demonstrate that our idea works well for small quark mass, though there should be further constraints to reach the perfect locking of two phenomena.

  9. Lattice quantum chromodynamics with approximately chiral fermions

    International Nuclear Information System (INIS)

    In this work we present Lattice QCD results obtained by approximately chiral fermions. We use the CI fermions in the quenched approximation to investigate the excited baryon spectrum and to search for the Θ+ pentaquark on the lattice. Furthermore we developed an algorithm for dynamical simulations using the FP action. Using FP fermions we calculate some LECs of chiral perturbation theory applying the epsilon expansion. (orig.)

  10. Nondipole Photoemission from Chiral Enantiomers of Camphor

    Science.gov (United States)

    Bowen, K. P.; Stolte, W. C.; Young, J. A.; Demchenko, I. N.; Guillemin, R.; Hemmers, O.; Piancastelli, M. N.; Lindle, D. W.

    2010-03-01

    K-shell photoemission from the carbonyl carbon in the chiral molecule camphor has been studied in the region just above the core-shell ionization threshold. Differences between angular distributions of emitted photoelectrons from the two enantiomers are attributed to the influence of chirality combined with nondipole effects in the photoemission process, despite the fact the measurements were taken using linearly polarized x-rays. The results suggest the possibility of a new form of linear dichroism.

  11. Tests of Chiral Perturbation Theory with COMPASS

    CERN Document Server

    Friedrich, Jan

    2010-01-01

    The COMPASS experiment at the CERN SPS studies with high precision pion-photon induced reactions via the Primakoff effect on nuclear targets. This offers the test of chiral perturbation theory (ChPT) in various channels: Pion Compton scattering allows to clarify the long-standing question of the pion polarisabilities, single neutral pion production is related to the chiral anomaly, and for the two-pion production cross sections exist as yet untested ChPT predictions.

  12. Tests of Chiral Perturbation Theory with COMPASS

    International Nuclear Information System (INIS)

    The COMPASS experiment at CERN studies with high precision pion-photon induced reactions on nuclear targets via the Primakoff effect. This offers the possibility to test chiral perturbation theory (ChPT) in various channels: Pion Compton scattering allows to clarify the longstanding question of the pion polarisabilities, single neutral pion production is related to the chiral anomaly, and for the two-pion production cross sections exist as yet untested ChPT predictions.

  13. Bringing chiral optical forces to dominance with optical nanofibers

    CERN Document Server

    Alizadeh, M H

    2016-01-01

    Transverse spin angular momentum (SAM) of light and associated transverse chiral optical forces have received tremendous attention recently as the latter may lead to an optical separation of chiral biomolecules. Previous schemes to generate chiral forces are plagued by the fact that the chiral optical forces are orders of magnitude smaller than conventional gradient and scattering forces. The relative magnitude of chiral and non-chiral forces represents a fundamental challenge for the implementation of chiral separation schemes. In this work we demonstrate that, by spatially separating the maxima of transverse spin density from the gradient of field intensity, in the vicinity of optical nanofibers and nanowires, chiral optical forces can emerge that are stronger than gradient and scattering forces. This finding has important implications for the design of improved optical separation schemes for chiral biomolecules.

  14. Ferrimagnetic Tb-Fe Alloy Thin Films: Composition and Thickness Dependence of Magnetic Properties and All-Optical Switching

    Directory of Open Access Journals (Sweden)

    Birgit eHebler

    2016-02-01

    Full Text Available Ferrimagnetic rare earth - transition metal Tb-Fe alloy thin films exhibit a variety of different magnetic properties, which depends strongly on composition and temperature. In this study, first the influence of the film thickness (5 - 85 nm on the sample magnetic properties was investigated in a wide composition range between 15 at.% and 38 at.% of Tb. From our results, we find that the compensation point, remanent magnetization, and magnetic anisotropy of the Tb-Fe films depend not only on the composition but also on the thickness of the magnetic film up to a critical thickness of about 20-30 nm. Beyond this critical thickness, only slight changes in magnetic properties are observed. This behavior can be attributed to a growth-induced modification of the microstructure of the amorphous films, which affects the short range order. As a result, a more collinear alignment of the distributed magnetic moments of Tb along the out-of-plane direction with film thickness is obtained. This increasing contribution of the Tb sublattice magnetization to the total sample magnetization is equivalent to a sample becoming richer in Tb and can be referred to as an effective composition. Furthermore, the possibility of all-optical switching, where the magnetization orientation of Tb-Fe can be reversed solely by circularly polarized laser pulses, was analyzed for a broad range of compositions and film thicknesses and correlated to the underlying magnetic properties.

  15. Ferrimagnetism and spin excitation in a Ni–Mn partially inverted spinel prepared using a modified polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Rafael A. [Programa de Pos-Graduação em Ciência e Tecnologia de Materiais (POSMAT), Universidade Estadual Paulista, Faculdade de Ciências, Caixa Postal 473, 17033-360 Bauru, São Paulo (Brazil); Institut des Sciences Chimiques de Rennes – UMR 6226, Université de Rennes 1, F-35042 Rennes (France); Tedesco, Julio C.G.; Birk, Jonas O. [The Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Kalceff, Walter, E-mail: wkalceff@uts.edu.au [School of Physics and Advanced Materials, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007 (Australia); Yokaichiya, Fabiano [Laboratório Nacional de Luz Síncrotron (LNLS), Caixa Postal 6192, CEP 13083-970 Campinas, São Paulo (Brazil); Comissao Nacional de Energia Nuclear (CNEN), Instituto de Pesquisas Energeticas e Nucleares (IPEN), Reactor Multiproposito Brasileiro - RMB, Avenida Lineo Prestes 2242, Bloco A, Cidade Universitaria Armando Salles de Oliveira, Sao Paulo (Brazil); Rasmussen, Nina [The Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Peña, Octavio [Institut des Sciences Chimiques de Rennes – UMR 6226, Université de Rennes 1, F-35042 Rennes (France); Henry, Paul F. [European Spallation Source ESS AB, Box 176, 22100 Lund (Sweden); Simeoni, Giovanna G. [Heinz Maier-Leibnitz Zentrum (MLZ) and Physics Department, Technische Universität München, Lichtenbergstr. 1, 85748 Garching (Germany); Bordallo, Heloisa N. [The Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); European Spallation Source ESS AB, Box 176, 22100 Lund (Sweden); and others

    2014-07-01

    We demonstrate that a Ni–Mn oxide partially inverted spinel (Ni{sub 1−ν}Mn{sub ν})[Ni{sub ν}Mn{sub 2−ν}]O{sub 4} having inversion degree ν ≈ 0.8 and produced by a modified polymeric precursor method exhibits behaviour previously reported only in monophased samples. The structure of the specimen was determined using Rietveld analysis of X-ray and neutron powder diffraction data, showing that at room temperature the material crystallizes in the Fd3{sup ¯}m space group with a lattice constant a = 8.392 Å. Combining magnetization measurements with neutron powder diffraction, we show that the magnetic structure of this spinel is associated with the interplay between the ferromagnetic and antiferromagnetic lattices which coexist due to the cations' presence on both tetrahedral and octahedral sites. Our analysis of the neutron diffraction data confirms the postulated magnetic structure involving a star-like moment arrangement, arising from competition for the B (octahedral) spinel sites by the Ni and Mn cations. Finally, we show that strong magnetic fluctuations are observed in the inelastic neutron scattering data. - Highlights: • Ni–Mn oxide partially-inverted spinel made by modified polymeric precursor method. • Magnetic measurements showed a ferrimagnetic and a parasitic magnetic transition. • NPD revealed a magnetic structure consistent with a star-like moment arrangement. • INS measurements indicated four distinct temperature-dependent magnetic regimes.

  16. Ferrimagnetic ordering and spin entropy of field-dependent intermediate spins in Na0.82CoO2

    Science.gov (United States)

    Shu, G. J.; Chou, F. C.

    2016-04-01

    The peculiar field-dependent magnetism of Na0.82CoO2 has been investigated through an analysis of its dc and ac spin susceptibilities. To account for the easily activated narrow b2 g-a1 g gap of the crystal field for Co in the cobalt oxide layer, the spin-state transition of Co3 + (3 d6 ) between the low-spin (LS) state b2g 2a1g 0 of S =0 and the intermediate-spin (IS) state b2g 1a1g 1 of S =1 is thus seen as thermally activated and exhibits a Boltzmann distribution. The IS state of Co3 + within each √{13 }a hexagonal superlattice formed by the S =1 /2 state of the Co4 + ions appears randomly within each supercell and shows significant temperature and field dependence. The magnetic field is found to assist in pinning down the thermally activated state of Co3 + and swings the Boltzmann distribution weight toward a higher fraction of the IS state. The field dependence of the in-plane magnetic moment from the added number of S =1 spins is used to explain the origin of A -type antiferromagnetic (AF) ordering, particularly that the ferromagnetic (FM)-like behavior below TN at low field is actually a ferrimagnetic IS spin ordering of Co3 +.

  17. Staggered heavy baryon chiral perturbation theory

    Science.gov (United States)

    Bailey, Jon A.

    2008-03-01

    Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms of O(mπ3), which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms of O(a2). The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in detail. The resulting chiral forms are appropriate to lattice results obtained with operators already in use and could be used to study the restoration of taste symmetry in the continuum limit. I assume that the fourth root of the fermion determinant can be incorporated in staggered chiral perturbation theory using the replica method.

  18. Interplay between chiral and deconfinement phase transitions

    Directory of Open Access Journals (Sweden)

    Mukherjee T.K.

    2011-04-01

    Full Text Available By using the dressed Polyakov loop or dual chiral condensate as an equivalent order parameter of the deconfinement phase transition, we investigate the relation between the chiral and deconfinement phase transitions at finite temperature and density in the framework of three-flavor Nambu-Jona-Lasinio (NJL model. It is found that in the chiral limit, the critical temperature for chiral phase transition coincides with that of the dressed Polyakov loop in the whole (T,µ plane. In the case of explicit chiral symmetry breaking, it is found that the phase transitions are flavor dependent. For each flavor, the transition temperature for chiral restoration $T^{mathcal{X}}_c$ is smaller than that of the dressed Polyakov loop $T^{mathcal{D}}_c$ in the low baryon density region where the transition is a crossover, and, the two critical temperatures coincide in the high baryon density region where the phase transition is of first order. Therefore, there are two critical end points, i.e, $T^{u,d}_{CEP}$ and $T^{s}_{CEP}$ at finite density. We also explain the feature of $T^{mathcal{X}}_c$ = $T^{mathcal{D}}_c$ in the case of 1st and 2nd order phase transitions, and $T^{mathcal{X}}_c$ < $T^{mathcal{D}}_c$ in the case of crossover, and expect this feature is general and can be extended to full QCD theory.

  19. Chiral Magnetic Effect in Hydrodynamic Approximation

    CERN Document Server

    Zakharov, Valentin I

    2012-01-01

    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 ballistic transport along magnetic field taking place in equilibrium and in absence of a driving force. The basic limitat...

  20. Interplay between chiral and deconfinement phase transitions

    CERN Document Server

    Xu, Fukun; Chen, Huan; Huang, Mei

    2011-01-01

    By using the dressed Polyakov loop or dual chiral condensate as an equivalent order parameter of the deconfinement phase transition, we investigate the relation between the chiral and deconfinement phase transitions at finite temperature and density in the framework of three-flavor Nambu--Jona-Lasinio (NJL) model. It is found that in the chiral limit, the critical temperature for chiral phase transition coincides with that of the dressed Polyakov loop in the whole $(T,\\mu)$ plane. In the case of explicit chiral symmetry breaking, it is found that the phase transitions are flavor dependent. For each flavor, the transition temperature for chiral restoration $T_c^{\\chi}$ is smaller than that of the dressed Polyakov loop $T_c^{{\\cal D}}$ in the low baryon density region where the transition is a crossover, and, the two critical temperatures coincide in the high baryon density region where the phase transition is of first order. Therefore, there are two critical end points, i.e, $T_{CEP}^{u,d}$ and $T_{CEP}^{s}$ a...

  1. Life's First Handshake - Discovery of the Interstellar Chiral Molecule Propylene Oxide

    Science.gov (United States)

    McGuire, Brett A.; Carroll, P. Brandon; Loomis, Ryan A.; Finneran, Ian A.; Jewell, Philip R.; Remijan, Anthony J.; Blake, Geoffrey A.

    2016-06-01

    Life on Earth relies on chiral molecules, that is, species not superimposable on their mirror images. This manifests itself in the selection of a single molecular handedness, or homochirality, across the biosphere, and is perhaps most readily apparent in the large enhancement in biological activity of particular amino acid and sugar enantiomers. Yet, the ancestral origin of biological homochirality remains a mystery. The non-racemic ratios in some organics isolated from primitive meteorites hint at a primordial chiral seed, but even these samples have experienced substantial processing during planetary assembly, obscuring their complete histories. To determine the underlying origin of any enantiomeric excess, it is critical to understand the molecular gas from which these molecules originated. Here, we present the first extra-solar, astronomical detection of a chiral molecule, propylene oxide (CH3CHCH2O), in absorption toward the Galactic Center. We discuss the implications of the detection on observational searches to determine a primordial chiral excess, as well as the state of laboratory efforts in these areas.

  2. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG; XuMu

    2001-01-01

    Chiral Quest's Toolbox Approach: During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. However, there is no universal chiral ligand or catalyst for solving problems in enantioselective transformations. The focus of Chiral Quest's research is to develop a useful chiral toolbox for strategically important asymmetric catalytic reactions by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts. The toolbox approach addresses significant problems in organic stereochemistry and has resulted in practical methods for the synthesis of chiral pharmaceuticals and agrochemicals  ……

  3. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral Quest's Toolbox Approach: During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. However, there is no universal chiral ligand or catalyst for solving problems in enantioselective transformations. The focus of Chiral Quest's research is to develop a useful chiral toolbox for strategically important asymmetric catalytic reactions by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts. The toolbox approach addresses significant problems in organic stereochemistry and has resulted in practical methods for the synthesis of chiral pharmaceuticals and agrochemicals

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

    Science.gov (United States)

    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.

  5. A chiral rhenium complex with predicted high parity violation effects: synthesis, stereochemical characterization by VCD spectroscopy and quantum chemical calculations

    CERN Document Server

    Saleh, Nidal; Roisnel, Thierry; Guy, Laure; Bast, Radovan; Saue, Trond; Darquié, Benoît; Crassous, Jeanne

    2015-01-01

    With their rich electronic, vibrational, rotational and hyperfine structure, molecular systems have the potential to play a decisive role in precision tests of fundamental physics. For example, electroweak nuclear interactions should cause small energy differences between the two enantiomers of chiral molecules, a signature of parity symmetry breaking. Enantioenriched oxorhenium(VII) complexes S-(-)- and R-(+)-3 bearing a chiral 2-methyl-1-thio-propanol ligand have been prepared as potential candidates for probing molecular parity violation effects via high resolution laser spectroscopy of the Re=O stretching. Although the rhenium atom is not a stereogenic centre in itself, experimental vibrational circular dichroism (VCD) spectra revealed a surrounding chiral environment, evidenced by the Re=O bond stretching mode signal. The calculated VCD spectrum of the R enantiomer confirmed the position of the sulfur atom cis to the methyl, as observed in the solid-state X-ray crystallographic structure, and showed the ...

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

    Science.gov (United States)

    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. PMID:26882341

  7. Salan ligands assembled around chiral bipyrrolidine: predetermination of chirality around octahedral Ti and Zr centres.

    Science.gov (United States)

    Sergeeva, Ekaterina; Kopilov, Jacob; Goldberg, Israel; Kol, Moshe

    2009-06-01

    The first synthesis of Salan ligands assembled around the chiral 2,2'-bipyrrolidine backbone is described; as chelation to a metal can only occur via specific faces of the two pyrrolidine nitrogens, these ligands lead to predetermined chirality at metal centres of octahedral titanium and zirconium complexes. PMID:19462084

  8. The asymmetric alkylation of dimethylhydrazones; intermolecular chirality transfer using sparteine as chiral ligand.

    Science.gov (United States)

    McSweeney, Christina M; Foley, Vera M; McGlacken, Gerard P

    2014-12-01

    The asymmetric alkylation of ketones represents a fundamental transformation in organic chemistry. Chiral auxiliaries have been used almost exclusively for this transformation. Herein we describe a strategy for the generation of enantiomerically enriched α-alkylated ketones up to an er of 83 : 17, using a chiral ligand protocol.

  9. Ferrimagnetic ordering of single crystal Fe1-xGax thin films

    Energy Technology Data Exchange (ETDEWEB)

    McClure, A.; Arenholz, E.; Idzerda, Y. U.

    2009-10-19

    Molecular beam epitaxy was used to deposit body centered cubic single crystal Fe{sub 1-x}Ga{sub x} thin films on MgO(001) and ZnSe/GaAs(001) substrates well beyond the bulk stability concentration of about 28%. The crystal quality of the substrate surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetization of the samples as a function of Ga is found to decrease more rapidly than a simple dilution effect, and element-specific x-ray magnetic circular dichroism ascribes this trend to a decrease in the Fe moment and an induced moment in the Ga that is antialigned to the Fe moment.

  10. The Design of Molecular Hosts, Guests, and Their Complexes.

    Science.gov (United States)

    Cram, Donald J.

    1988-01-01

    Describes the origins, definitions, tools, and principles of host-guest chemistry. Gives examples of chiral recognition in complexation, of partial transacylase mimics, of caviplexes, and of a synthetic molecular cell. (Author/RT)

  11. Magnetohydrodynamics of Chiral Relativistic Fluids

    CERN Document Server

    Boyarsky, Alexey; Ruchayskiy, Oleg

    2015-01-01

    We study the dynamics of a plasma of charged relativistic fermions at very high temperature $T\\gg m$, where $m$ is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magneto-hydrodynamical description of the evolution of such a plasma. We show that, as compared to conventional MHD for a plasma of non-relativistic particles, the hydrodynamical description of the relativistic plasma involves new degrees of freedom described by a pseudo-scalar field originating in a local asymmetry in the densities of left-handed and right-handed fermions. This field can be interpreted as an effective axion field. Taking into account the chiral anomaly we present dynamical equations for the evolution of this field, as well as of other fields appearing in the MHD description of the plasma. Due to its non-linear coupling to helical magnetic fields, the axion field significantly affects the dynamics of a magnetized plasma and can give rise to a novel type of inverse cascade.

  12. Separation and Structure of Chiral S—Malic Acid Hydrate

    Institute of Scientific and Technical Information of China (English)

    NIE,Jing-Jing; WU,Jing-Yun; 等

    2002-01-01

    Crystals of the chiral malic acid hydrate (C4H6O5·H2O) were unexpectedly obtained from an ethanol/water solution containing racemic D,L-malic acid and L-asparagine.The crystal belongs to orthorhombic space group P212121 with cell dimensions of a=0.5576(1),b=0.9818(2),c=1.1793(2)nm,V=0.6455(2)nm3,Z=4,μ(Mo Kα)=0.152mm-1,F(000)=320,Dc=1.565g·cm-3,R=0.051,wR=0.136 for 657 observed reflections [I>2σ(I)].The significant difference in bond distances for carboxyl groups suggests that the crystal consist of malate anion and protonized crystalline water.This is a report for direct separation of racemic mixture,i.e.,whthout the formation of a molecular complex of raceme with a chiral separating reagent.

  13. Separation and Structure of Chiral S-Malic Acid Hydrate

    Institute of Scientific and Technical Information of China (English)

    NIE,Jing-Jing(聂晶晶); XU,Duan-Jun(徐端钧); WU,Jing-Yun(吴景云); CHIANG,Michael Y.(蒋燕南)

    2002-01-01

    Crystals of the chiral malic acid hydrate ( C4H6O5@H2O ) were unexpectedly obtained from an ethanol ethanol/water solution containing racemic D,L-malic acid and L-asparagine. The crystal belongs to orthorhombic space group P21 21 21 with cell dimensions of a=0.5576(1), b=0.9818(2), c=1.1793(2) nm, V=0.9455(2) nm3, Z=4, μ(Mo Kα) =0.152 mm-1, F(000) =320, Dc= 1.565 g@cm-3, R =0.051, wR =0.136 for 657 observed reflections [I>2σ(I)]. The significant difference in bond distances for carboxyl groups suggests that the crystal consist of malate anion and protonized crystalline water. This is a report for direct separation of racemic mixture, i.e., without the formation of a molecular complex of raceme with a chiral separating reagent.

  14. Influence of kaolinite on chiral hydrolysis of methyl dichlorprop enantiomers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The effect of kaolinite on the enzymatic chiral hydrolysis of methyl dichlorprop enantiomers ((R,S)-methyl-2-(2,4-dichlorophenoxy) propanoic acid, 2,4-DPM) was investigated using chiral gas chromatography. Compared with the control without kaolinite, the enantiomeric ratio (ER) increased from 1.35 to 8.33 and the residual ratio of 2,4-DPM decreased from 60.89% to 41.55% in the presence of kaolinite. Kaolinite likely had emotion influence on lipase activity and its enantioselectivity.Moreover, the amount of kaolinite added was also found to be a sensitive factor affecting the enantioselective hydrolysis of 2,4-DPM. Fourier transform infrared (FTIR) spectroscopy studies of the interaction of lipase with kaolinite provided insight into the molecular structure of the complex and offered explanation of the effects of kaolinite on enzymatic hydrolysis of 2,4-DPM.Spectra showed that the effect of kaolinite on the hydrolysis of 2,4-DPM was affected by adsorption of lipase on kaolinite and changes of adsorbed lipase conformation, which led to the modified enantioselectivity.

  15. Enantioselective catalytic syntheses of alpha-branched chiral amines

    DEFF Research Database (Denmark)

    Brase, S.; Baumann, T.; Dahmen, S.;

    2007-01-01

    Chiral amines play a pivotal role in fine chemical and natural product syntheses and the design of novel materials.......Chiral amines play a pivotal role in fine chemical and natural product syntheses and the design of novel materials....

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

    Science.gov (United States)

    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).

  17. METHODS DEVELOPMENT FOR THE ANALYSIS OF CHIRAL PESTICIDES

    Science.gov (United States)

    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...

  18. Preparation and studies on surface modifications of calcium-silico-phosphate ferrimagnetic glass-ceramics in simulated body fluid

    International Nuclear Information System (INIS)

    The structure and magnetic behaviour of 34SiO2-(45 - x) CaO-16P2O5-4.5 MgO-0.5 CaF2 - x Fe2O3 (where x = 5, 10, 15, 20 wt.%) glasses have been investigated. Ferrimagnetic glass-ceramics are prepared by melt quench followed by controlled crystallization. The surface modification and dissolution behaviour of these glass-ceramics in simulated body fluid (SBF) have also been studied. Phase formation and magnetic behaviour have been studied using XRD and SQUID magnetometer. The room temperature Moessbauer study has been done to monitor the local environment around Fe cations and valence state of Fe ions. X-ray photoelectron spectroscopy (XPS) was used to study the surface modification in glass-ceramics when immersed in simulated body fluid. Formation of bioactive layer in SBF has been ascertained using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The SBF solutions were analyzed using an absorption spectrophotometer. The magnetic measurements indicated that all these glasses possess paramagnetic character and the [Fe2+/Fe3+] ions ratio depends on the composition of glass and varied with Fe2O3 concentration in glass matrix. In glass-ceramics saturation magnetization increases with increase in amount of Fe2O3. The nanostructure of hematite and magnetite is formed in the glass-ceramics with 15 and 20 wt.% Fe2O3, which is responsible for the magnetic property of these glass-ceramics. Introduction of Fe2O3 induces several modifications at the glass-ceramics surface when immersed in SBF solution and thereby affecting the surface dissolution and the formation of the bioactive layer.

  19. The Practical Asymmetric Syntheses of Key Chiral Intermediates of Chiral Drug from Four-Carbon Chiral Pool

    Institute of Scientific and Technical Information of China (English)

    MI; AiQiao

    2001-01-01

    (S)-or (R)-2-Amino-4-phenylbutyric acid and (S)-or (R)-2-hydroxy-4-phenylbutyric acid and their ethyl esters are key chiral intermediates for the preparation of angiotensin converting enzyme inhibitors (ACEI) and other chiral drugs. Their practically asymmetric synthetic methods in large scale from four-carbon chiral pool, commercially available L-aspartic acid and L-malic acid, will be presented (as scheme).  (S)-2-Amino-4-phenylbutyric acid and its ethyl ester hydrochloride were prepared from the easily available L-aspartic acid via activation by forming anhydride hydrochloride, Friedel-Crafts reaction with benzene, hydrogenolysis and esterification with ethanol in the presence of thionyl chloride in overall yield of 80% and 73.6% respectively with 99% ee. We first used amino acid anhydride hydrochloride as the acylating agent in Friedel-Crafts reaction without racemization. [1]……

  20. The Practical Asymmetric Syntheses of Key Chiral Intermediates of Chiral Drug from Four-Carbon Chiral Pool

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ (S)-or (R)-2-Amino-4-phenylbutyric acid and (S)-or (R)-2-hydroxy-4-phenylbutyric acid and their ethyl esters are key chiral intermediates for the preparation of angiotensin converting enzyme inhibitors (ACEI) and other chiral drugs. Their practically asymmetric synthetic methods in large scale from four-carbon chiral pool, commercially available L-aspartic acid and L-malic acid, will be presented (as scheme). (S)-2-Amino-4-phenylbutyric acid and its ethyl ester hydrochloride were prepared from the easily available L-aspartic acid via activation by forming anhydride hydrochloride, Friedel-Crafts reaction with benzene, hydrogenolysis and esterification with ethanol in the presence of thionyl chloride in overall yield of 80% and 73.6% respectively with 99% ee. We first used amino acid anhydride hydrochloride as the acylating agent in Friedel-Crafts reaction without racemization. [1

  1. Chiral density wave in nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Heinz, Achim [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Giacosa, Francesco [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Rischke, Dirk H. [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany)

    2015-01-15

    Inspired by recent work on inhomogeneous chiral condensation in cold, dense quark matter within models featuring quark degrees of freedom, we investigate the chiral density-wave solution in nuclear matter at zero temperature and nonvanishing baryon number density in the framework of the so-called extended linear sigma model (eLSM). The eLSM is an effective model for the strong interaction based on the global chiral symmetry of quantum chromodynamics (QCD). It contains scalar, pseudoscalar, vector, and axial-vector mesons as well as baryons. In the latter sector, the nucleon and its chiral partner are introduced as parity doublets in the mirror assignment. The eLSM simultaneously provides a good description of hadrons in vacuum as well as nuclear matter ground-state properties. We find that an inhomogeneous phase in the form of a chiral density wave is realized, but only for densities larger than 2.4ρ{sub 0}, where ρ{sub 0} is the nuclear matter ground-state density.

  2. Chiral superfluidity for the heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kalaydzhyan, T. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)

    2013-02-15

    We argue that the strongly coupled quark-gluon plasma formed at LHC and RHIC can be considered as a chiral superfluid. The ''normal'' component of the fluid is the thermalized matter in common sense, while the ''superfluid'' part consists of long wavelength (chiral) fermionic states moving independently. We use the bosonization procedure with a finite cut-off and obtain a dynamical axion-like field out of the chiral fermionic modes. Then we use relativistic hydrodynamics for macroscopic description of the effective theory obtained after the bosonization. Finally, solving the hydrodynamic equations in gradient expansion, we find that in the presence of external electromagnetic fields the motion of the ''superfluid'' component gives rise to the chiral magnetic, chiral electric and dipole wave effects. Latter two effects are specific for a two-component fluid, which provides us with crucial experimental tests of the model. By considering probe quarks one can show that the fermionic spectrum at the intermediate temperatures (T{sub c}

  3. Enantioselective binding of amino acids and amino alcohols by self-assembled chiral basket-shaped receptors

    NARCIS (Netherlands)

    Escuder, B.; Rowan, A.E.; Feiters, M.C.; Nolte, R.J.M.

    2004-01-01

    Amino acid appended diphenylglycoluril-based chiral molecular receptors 2 and 3 have been prepared and their aggregation has been studied in water at various pH's and in chloroform. The binding of several biologically relevant guests with aromatic moieties to these aggregates has been studied with U

  4. Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

    Directory of Open Access Journals (Sweden)

    Tomoya Hayata

    2015-05-01

    Full Text Available We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement of heavy quarks.

  5. Chiral heat wave and mixed waves in kinetic theory

    CERN Document Server

    Frenklakh, D

    2016-01-01

    We study collective excitations in hot rotating chiral media in presence of magnetic field in kinetic theory, namely Chiral Heat Wave and its' mixings with Chiral Vortical Wave and Chiral Magnetic Wave. Our results for velocities of these waves have slight alterations from those obtained earlier. We explain the origin of these alterations and also give the most general expressions for the velocities of all these waves in hydrodynamic approach.

  6. Chirality - The forthcoming 160th Anniversary of Pasteur's Discovery

    OpenAIRE

    Molčanov, Krešimir; Kojić-Prodić, Biserka

    2007-01-01

    The presented review on chirality is dedicated to the centennial birth anniversary of Nobel laureate Vladimir Prelog and 160 years of Pasteur's discovery of chirality on tartrates. Chirality has been recognized in nature by artists and architects, who have used it for decorations and basic constructions, as shown in the Introduction. The progress of science through history has enabled the gathering of knowledge on chirality and its many ways of application. The key historical discoveries abou...

  7. Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

    Energy Technology Data Exchange (ETDEWEB)

    Hayata, Tomoya, E-mail: hayata@riken.jp [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Theoretical Research Division, Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Yamamoto, Arata [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Theoretical Research Division, Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan)

    2015-05-11

    We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement of heavy quarks.

  8. Two-color QCD with chiral chemical potential

    Science.gov (United States)

    Braguta, V. V.; Goy, V. A.; Ilgenfritz, E.-M.; Kotov, A. Yu.; Molochkov, A. V.; Müller-Preussker, M.; Petersson, B.; Schreiber, A.

    2016-01-01

    The phase diagram of two-color QCD with a chiral chemical potential is studied on the lattice. The focus is on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulations are carried out with dynamical staggered fermions without rooting. The dependence of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented.

  9. Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

    Science.gov (United States)

    Hayata, Tomoya; Yamamoto, Arata

    2015-05-01

    We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement of heavy quarks.

  10. Inhomogeneous Polyakov loop induced by inhomogeneous chiral condensates

    OpenAIRE

    Tomoya Hayata; Arata Yamamoto

    2015-01-01

    We study the spatial inhomogeneity of the Polyakov loop induced by inhomogeneous chiral condensates. We formulate an effective model of gluons on the background fields of chiral condensates, and perform its lattice simulation. On the background of inhomogeneous chiral condensates, the Polyakov loop exhibits an in-phase spatial oscillation with the chiral condensates. We also analyze the heavy quark potential and show that the inhomogeneous Polyakov loop indicates the inhomogeneous confinement...

  11. Novel Lifshitz point for chiral transition in the magnetic field

    Directory of Open Access Journals (Sweden)

    Toshitaka Tatsumi

    2015-04-01

    Full Text Available Based on the generalized Ginzburg–Landau theory, chiral phase transition is discussed in the presence of magnetic field. Considering the chiral density wave we show that chiral anomaly gives rise to an inhomogeneous chiral phase for nonzero quark-number chemical potential. Novel Lifshitz point appears on the vanishing chemical potential line, which may be directly explored by the lattice QCD simulation.

  12. Elastic properties of chiral, anti-chiral, and hierarchical honeycombs: A simple energy-based approach

    Directory of Open Access Journals (Sweden)

    Davood Mousanezhad

    2016-03-01

    Full Text Available The effects of two geometric refinement strategies widespread in natural structures, chirality and self-similar hierarchy, on the in-plane elastic response of two-dimensional honeycombs were studied systematically. Simple closed-form expressions were derived for the elastic moduli of several chiral, anti-chiral, and hierarchical honeycombs with hexagon and square based networks. Finite element analysis was employed to validate the analytical estimates of the elastic moduli. The results were also compared with the numerical and experimental data available in the literature. We found that introducing a hierarchical refinement increases the Young’s modulus of hexagon based honeycombs while decreases their shear modulus. For square based honeycombs, hierarchy increases the shear modulus while decreasing their Young’s modulus. Introducing chirality was shown to always decrease the Young’s modulus and Poisson’s ratio of the structure. However, chirality remains the only route to auxeticity. In particular, we found that anti-tetra-chiral structures were capable of simultaneously exhibiting anisotropy, auxeticity, and remarkably low shear modulus as the magnitude of the chirality of the unit cell increases.

  13. Chiral symmetry in hadron physics methods and ideas of chiral symmetry

    International Nuclear Information System (INIS)

    Methods and ideas of chiral symmetry is presented based on a lecture note to help the future researches in hadron dynamics along with the chiral symmetry. The chiral symmetry was originally developed as the symmetry between currents before the discovery of QCD. It has come to be understood in principle by now that the symmetry is spontaneously broken and only the part of flavor symmetry remains explicitly. In QCD, however, the chiral symmetry has come to be regarded as the base of the symmetry of the global flavor space of quarks. One of the recent topics of the lattice gauge theory is how the hadron properties will change when the broken symmetry is going to be restored. Since the chiral symmetry is global, it is different from gauge symmetry which is local. It explains the degeneracy of hadron masses and relations between the elements of S-matrix in which same number of particles are included. In practice, however, the symmetry of the axial part is spontaneously broken and pions which behave like gauge particles come to play. Chiral symmetry is defined as the (internal) flavor symmetry for the two independent chirality states of quarks. It discriminates two different fundamental quarks defined for the Lorentz groups O(4) - SL(2, C). The symmetry transformation itself is, however, different from the chirality. They should not be confused. In this lecture note, fundamental properties of pions are described on the basis of the interaction with nucleons at first. General properties of the chiral symmetry and some of the low energy theorems on current algebra are introduced. Then, linear sigma model and nonlinear sigma model are introduced. Then the Skyrme-model, which provides an idea as important as quarks, is explained. One of the interesting topics at present is to restore the broken axial symmetry experimentally to investigate the mechanism of symmetry breaking. (S. Funahashi)

  14. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.

  15. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG; XiaoMing

    2001-01-01

    Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.  ……

  16. Chiral doublet bands and energy-level crossing

    Institute of Scientific and Technical Information of China (English)

    QI Bin; MENG Jie; ZHANG Shuang-Quan; WANG Shou-Yu; PENG Jing

    2009-01-01

    Different definitions for chiral doublet bands based on excitation energies, B(E2) and B(M1) respectively are discussed in the triaxial particle rotor model. For the ideal chiral geometry, the selection rules of the electromagnetic transitions in different band definitions are illustrated. It is also shown that the energy-level crossings between chiral doublet bands may occur.

  17. How is chiral symmetry restored at finite density?

    OpenAIRE

    Tatsumi, T.; Nakano, E.

    2005-01-01

    Taking into account pseudoscalar as well as scalar condensates, we reexamine the chiral restoration path on the chiral manifold. We shall see both condensates coherently produce a density wave at a certain density, which delays chiral restoration as density or temperature is increased.

  18. A strict QCD inequality and mechanisms for chiral symmetry breaking

    International Nuclear Information System (INIS)

    A strict QCD inequality allows one to discuss mechanisms proposed for breaking the chiral symmetry in QCD. ''Order parameters'' are identified such that if sufficiently many gauge field configurations contribute to them, spontaneous chiral symmetry breaking follows. As an application the role of instantons is discussed in chiral symmetry breaking in QCD. (orig.)

  19. Chiral Ordering in the Four-Dimensional XY Spin Glass

    OpenAIRE

    Jain, S.

    1997-01-01

    The chiral glass behaviour of the nearest-neighbour random-bond XY spin glass in four dimensions is studied by Monte Carlo simulations. A chiral glass transition at $T_{cg}=0.90\\pm 0.05$ is found by a finite-size scaling analysis of the results. The associated chiral correlation-length exponent is estimated to be $\

  20. 布洛芬手性拆分分子印迹复合膜的制备与表征%Preparation and evaluation of molecular imprinted composite membranes for chiral resolution of ibuprofen

    Institute of Scientific and Technical Information of China (English)

    赵潇; 秦培勇

    2013-01-01

    以接枝环糊精的醋酸纤维素复合物为铸膜材料,S-布洛芬为印迹分子,采用相转化法制备了用于手性分离的分子印迹膜;用FT-IR和SEM测试手段对膜的化学组成和结构形态进行了表征;通过渗透实验考察了该分子印迹膜对外消旋布洛芬的手性拆分性能.结果表明在β-环糊精接枝率为29.01%(质量分数),模板分子浓度比为1∶10,铸膜液质量分数为12.5%的条件下,分子印迹膜对右旋布洛芬的分离因子可达2.09.%Molecular imprinted membranes of S-ibuprofen were prepared by the phase inversion technique with cel lulose acetate-β-cyclodextrin copolymer ( P ( CA-co-β-CD ) ). To characterize P( CA-co-β-CD) , a biosensor was used to measure its grafting ratio, and P( CA-co-β-CD) polymers with different grafting ratios were used to prepare membranes. A copolymer -DMF solution with a S-ibuprofen template was coagulated in water at 20 ℃. Increasing P(CA-co-β-CD) grafting ratio resulted in an increase in S-ibuprofen recognition properties of the resulting membrane. The S-ibuprofen imprinted membrane prepared with P( CA-co-β-CD) showed good selectivity to S-ibuprofen. Surface and cross-section morphologies of the membranes were analyzed by scanning electron microscopy. High-performance liquid chromatography was used for the quantification of ibuprofen in the isolated fraction. Under the optimum conditions of β-CD grafting yield of 29. 01% (mass fraction) , polymer mass fraction of 12. 5% , and a concentration ratio of CA to S-Ibu of 1:10, the separation factor reached a maximum value of 2. 09.