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Sample records for high chiral recognition

  1. Chiral separation of α-cyclohexylmandelic acid enantiomers by high-speed counter-current chromatography with biphasic recognition

    Science.gov (United States)

    Tong, Shengqiang

    2010-01-01

    This work concentrates on a novel chiral separation technology named biphasic recognition applied to resolution of α-cyclohexylmandelic acid enantiomers by high-speed counter-current chromatography (HSCCC). The biphasic chiral recognition HSCCC was performed by adding lipophilic (−)-2-ethylhexyl tartrate in the organic stationary phase and hydrophilic hydroxypropyl-β-cyclodextrin in the aqueous mobile phase, which preferentially recognized the (−)-enantiomer and (+)-enantiomer, respectively. The two-phase solvent system composed of n-hexane-methyl tert-butyl ether-water (9:1:10, v/v/v) with the above chiral selectors was selected according to the partition coefficient and separation factor of the target enantiomers. Various parameters involved in the chiral separation were investigated, namely the types of the chiral selector (CS); the concentration of each chiral selector; pH of the mobile phase; and the separation temperature. The mechanism involved in this biphasic recognition chiral separation by HSCCC was discussed. Langmuirian isotherm was employed to estimate the loading limits for each chiral selector. The overall experimental results show that the HSCCC separation of enantiomer based on biphasic recognition is much more efficient than the traditional monophasic recognition chiral separation, since it utilizes the cooperation of both lipophilic and hydrophilic chiral selectors. PMID:20303497

  2. Chiral recognition in separation science: an overview.

    Science.gov (United States)

    Scriba, Gerhard K E

    2013-01-01

    Chiral recognition phenomena play an important role in nature as well as analytical separation sciences. In separation sciences such as chromatography and capillary electrophoresis, enantiospecific interactions between the enantiomers of an analyte and the chiral selector are required in order to observe enantioseparations. Due to the large structural variety of chiral selectors applied, different mechanisms and structural features contribute to the chiral recognition process. This chapter briefly illustrates the current models of the enantiospecific recognition on the structural basics of various chiral selectors.

  3. Chiral recognition in amyloid fiber growth.

    Science.gov (United States)

    Torbeev, Vladimir; Grogg, Marcel; Ruiz, Jérémy; Boehringer, Régis; Schirer, Alicia; Hellwig, Petra; Jeschke, Gunnar; Hilvert, Donald

    2016-05-01

    Insoluble amyloid fibers represent a pathological signature of many human diseases. To treat such diseases, inhibition of amyloid formation has been proposed as a possible therapeutic strategy. d-Peptides, which possess high proteolytic stability and lessened immunogenicity, are attractive candidates in this context. However, a molecular understanding of chiral recognition phenomena for d-peptides and l-amyloids is currently incomplete. Here we report experiments on amyloid growth of individual enantiomers and their mixtures for two distinct polypeptide systems of different length and structural organization: a 44-residue covalently-linked dimer derived from a peptide corresponding to the [20-41]-fragment of human β2-microglobulin (β2m) and the 99-residue full-length protein. For the dimeric [20-41]β2m construct, a combination of electron paramagnetic resonance of nitroxide-labeled constructs and (13) C-isotope edited FT-IR spectroscopy of (13) C-labeled preparations was used to show that racemic mixtures precipitate as intact homochiral fibers, i.e. undergo spontaneous Pasteur-like resolution into a mixture of left- and right-handed amyloids. In the case of full-length β2m, the presence of the mirror-image d-protein affords morphologically distinct amyloids that are composed largely of enantiopure domains. Removal of the l-component from hybrid amyloids by proteolytic digestion results in their rapid transformation into characteristic long straight d-β2m amyloids. Furthermore, the full-length d-enantiomer of β2m was found to be an efficient inhibitor of l-β2m amyloid growth. This observation highlights the potential of longer d-polypeptides for future development into inhibitors of amyloid propagation. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  4. Chiral Recognition and Separation by Chirality-Enriched Metal-Organic Frameworks.

    Science.gov (United States)

    Das, Saikat; Xu, Shixian; Ben, Teng; Qiu, Shilun

    2018-05-16

    Endowed with chiral channels and pores, chiral metal-organic frameworks (MOFs) are highly useful; however, their synthesis remains a challenge given that most chiral building blocks are expensive. Although MOFs with induced chirality have been reported to avoid this shortcoming, no study providing evidence for the ee value of such MOFs has yet been reported. We herein describe the first study on the efficiency of chiral induction in MOFs using inexpensive achiral building blocks and fully recoverable chiral dopants to control the handedness of racemic MOFs. This method yielded chirality-enriched MOFs with accessible pores. The ability of the materials to form host-guest complexes was probed with enantiomers of varying size and coordination and in solvents with varying polarity. Furthermore, mixed-matrix membranes (MMMs) composed of chirality-enriched MOF particles dispersed in a polymer matrix demonstrated a new route for chiral separation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Chiral Recognition by Fluorescence: One Measurement for Two Parameters

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    Shanshan Yu

    2014-01-01

    Full Text Available This outlook describes two strategies to simultaneously determine the enantiomeric composition and concentration of a chiral substrate by a single fluorescent measurement. One strategy utilizes a pseudoenantiomeric sensor pair that is composed of a 1,1′-bi-2-naphthol-based amino alcohol and a partially hydrogenated 1,1′-bi-2-naphthol-based amino alcohol. These two molecules have the opposite chiral configuration with fluorescent enhancement at two different emitting wavelengths when treated with the enantiomers of mandelic acid. Using the sum and difference of the fluorescent intensity at the two wavelengths allows simultaneous determination of both concentration and enantiomeric composition of the chiral acid. The other strategy employs a 1,1′-bi-2-naphthol-based trifluoromethyl ketone that exhibits fluorescent enhancement at two emission wavelengths upon interaction with a chiral diamine. One emission responds mostly to the concentration of the chiral diamine and the ratio of the two emissions depends on the chiral configuration of the enantiomer but independent of the concentration, allowing both the concentration and enantiomeric composition of the chiral diamine to be simultaneously determined. These strategies would significantly simplify the practical application of the enantioselective fluorescent sensors in high-throughput chiral assay.

  6. Enantioseparation and chiral recognition mechanism of new chiral derivatives of xanthones on macrocyclic antibiotic stationary phases.

    Science.gov (United States)

    Fernandes, Carla; Tiritan, Maria Elizabeth; Cass, Quezia; Kairys, Visvaldas; Fernandes, Miguel Xavier; Pinto, Madalena

    2012-06-08

    A chiral HPLC method using four macrocyclic antibiotic chiral stationary phases (CSPs) has been investigated for determination of the enantiomeric purity of fourteen new chiral derivatives of xanthones (CDXs). The separations were performed with the CSPs Chirobiotic T, Chirobiotic TAG, Chirobiotic V and Chirobiotic R under multimodal elution conditions (normal-phase, reversed-phase and polar ionic mode). The analyses were performed at room temperature in isocratic mode and UV and CD detection at a wavelength of 254 nm. The best enantioselectivity and resolution were achieved on Chirobiotic R and Chirobiotic T CSPs, under normal elution conditions, with R(S) ranging from 1.25 to 2.50 and from 0.78 to 2.06, respectively. The optimized chromatographic conditions allowed the determination of the enantiomeric ratio of eight CDXs, always higher than 99%. In order to better understand the chromatographic behavior at a molecular level, and the structural features associated with the chiral recognition mechanism, computational studies by molecular docking were carried out using VDock. These studies shed light on the mechanisms involved in the enantioseparation for this important class of chiral compounds. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Chiral recognition with enantioselective ion exchangers based on carbamoylated cinchonan derivatives as chiral selectors for the HPLC enantioseparation

    International Nuclear Information System (INIS)

    Laemmerhofer, M.

    1996-11-01

    The high-performance liquid chromatographic (HPLC) separation of enantiomers is preferentially performed using chiral stationary phases (CSPs). If the chiral auxiliary (selector, SO) contains charged or ionizable groups one gets ion exchanger type CSPs which may bind and retain oppositely charged analytes (selectands, SAs). We prepared anion exchanger type CSPs with various quinine and quinidine carbarnates as chiral SOs immobilized either on porous or non-porous silica. These CSPs are able to resolve the enantiomers of a wide spectrum of chiral carboxylic, sulfonic, phosphonic, phosphoric acids and of many other chiral acidic solutes (e.g. N-derivatized alpha-, beta- , gamma-amino acids as 2,4-dinitrophenyl, 3,5-dinitrobenzoyl, benzoyl, acetyl, formyl, t.-butoxycarbonyl, benzyloxycarbonyl, 9-fluorenylmethoxycarbonyl, dansyl amino acids and peptides, alpha-arylalkylcarboxylic acids as profens, alpha-aryloxyalkylcarboxylic acids, alpha-arylthioalkylcarboxylic acids and acidic drugs like etodolac, proglumide, acenocournarol, leucovorin, omeprazole, pantoprazole) employing buffered aqueous mobile phases or non-aqueous mobile phases with buffer dissolved in the organic solvent. The influence of mobile phase parameters and other experimental conditions on retention and enantioselectivity has been evaluated for isocratic and gradient elution techniques, aided by the commercial method development computer software DryLab. Several 'Quantitative Structure-Retention Relationships' (QSRR) have been derived, which allowed prediction of enantioselectivity of new analytes and moreover the optimization of the SO-structure. Spectroscopic investigations as H-NMR, FTIR of certain SO-SA-complexes have been exerted to unveil the mechanism of chiral recognition. (author)

  8. Evaluation of the chiral recognition properties and the column performances of three chiral stationary phases based on cellulose for the enantioseparation of six dihydropyridines by high-performance liquid chromatography.

    Science.gov (United States)

    Yu, Jia; Tang, Jing; Yuan, Xiaowei; Guo, Xingjie; Zhao, Longshan

    2017-03-01

    Separations of six dihydropyridine enantiomers on three commercially available cellulose-based chiral stationary phases (Chiralcel OD-RH, Chiralpak IB, and Chiralpak IC) were evaluated with high-performance liquid chromatography (HPLC). The best enantioseparation of the six chiral drugs was obtained with a Chiralpak IC (250 × 4.6 mm i.d., 5 μm) column. Then the influence of the mobile phase including an alcohol-modifying agent and alkaline additive on the enantioseparation were investigated and optimized. The optimal mobile phase conditions and maximum resolution for every analyte were as follows respectively: n-hexane/isopropanol (85:15, v/v) for nimodipine (R = 5.80) and cinildilpine (R = 5.65); n-hexane/isopropanol (92:8, v/v) for nicardipine (R = 1.76) and nisoldipine (R = 1.92); and n-hexane/isopropanol/ethanol (97:2:1, v/v/v) for felodipine (R = 1.84) and lercanidipine (R = 1.47). Relative separation mechanisms are discussed based on the separation results, and indicate that the achiral parts in the analytes' structure showed an important influence on the separation of the chiral column. © 2017 Wiley Periodicals, Inc.

  9. Alternative method for determination of contaminated heparin using chiral recognition.

    Science.gov (United States)

    Szekely, J; Collins, M; Currie, C A

    2014-05-15

    Since 2008 a significant amount of work has focused on the development of methods to analyze contaminated heparin. This work focuses on utilizing heparin's ability to serve as a chiral selector as a means for determining contamination. Specifically, the effect of contamination on the separation of pheniramine and chloroquine enantiomers was explored. Separations were conducted using heparin contaminated with chondroitin sulfate at varying levels. For each pair of enantiomers, electrophoretic mobility and resolution were calculated. For pheniramine enantiomers, an increase in contamination leads to a decrease in the electrophoretic mobility and resolution. A linear relationship between contamination level and electrophoretic mobility of the pheniramine enantiomers was observed for the entire contamination range. A linear relationship was also found between contamination level and resolution of the enantiomers between 0 and 70 percent contamination. For the separation of chloroquine enantiomers, it was found that at low levels of contamination, the resolution of enantiomers was increased due to the secondary interaction between the chloroquine enantiomers and the chondroitin sulfate. Results of this study illustrate the potential of using chiral recognition as a means to determine heparin contamination as well as the improvement of the chiral resolution of chloroquine with the additional of low levels of chondroitin sulfate A. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Chiral recognition and determination of enantiomeric excess by mass spectrometry: A review

    International Nuclear Information System (INIS)

    Yu, Xiangying; Yao, Zhong-Ping

    2017-01-01

    Chiral analysis is of great importance to fundamental and applied research in chemical, biological and pharmaceutical sciences. Due to the superiority of mass spectrometry (MS) over other analytical methods in terms of speed, specificity and sensitivity, chiral analysis by MS has attracted much interest in recent years. Chiral analysis by MS typically involves introduction of a chiral selector to form diastereomers with analyte enantiomers, and comparison of the behaviors of diastereomers in MS. Chiral differentiation can be achieved by comparing the relative abundances of diastereomers, the thermodynamic or kinetic constants of ion-molecule reactions of diastereomers in the gas phase, the dissociation of diastereomers in MS/MS, or the mobility of diastereomers in ion mobility mass spectrometry. In this review, chiral recognition and determination of enantiomeric excess by these chiral MS methods were summarized, and the prospects of chiral analysis by MS were discussed. - Highlights: • Both chiral recognition and determination of enantiomeric excess by mass spectrometry are systematically reviewed. • Classification is based on the behavioral differences of diastereomers formed between chiral analytes and chiral selectors. • Development of ion mobility mass spectrometry for chiral differentiation is covered. • Various methods are highlighted and compared.

  11. Chiral recognition and determination of enantiomeric excess by mass spectrometry: A review

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiangying [College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong (China); State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation) and Shenzhen Key Laboratory of Food Biological Safety Control, Shenzhen Research Institute of Hong Kong Polytechnic University, Shenzhen 518057 (China); Yao, Zhong-Ping, E-mail: zhongping.yao@polyu.edu.hk [State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation) and Shenzhen Key Laboratory of Food Biological Safety Control, Shenzhen Research Institute of Hong Kong Polytechnic University, Shenzhen 518057 (China); Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules (Yanbian University), Ministry of Education, Yanji 133002, Jilin (China); State Key Laboratory of Chirosciences, Food Safety and Technology Research Centre and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region (China)

    2017-05-22

    Chiral analysis is of great importance to fundamental and applied research in chemical, biological and pharmaceutical sciences. Due to the superiority of mass spectrometry (MS) over other analytical methods in terms of speed, specificity and sensitivity, chiral analysis by MS has attracted much interest in recent years. Chiral analysis by MS typically involves introduction of a chiral selector to form diastereomers with analyte enantiomers, and comparison of the behaviors of diastereomers in MS. Chiral differentiation can be achieved by comparing the relative abundances of diastereomers, the thermodynamic or kinetic constants of ion-molecule reactions of diastereomers in the gas phase, the dissociation of diastereomers in MS/MS, or the mobility of diastereomers in ion mobility mass spectrometry. In this review, chiral recognition and determination of enantiomeric excess by these chiral MS methods were summarized, and the prospects of chiral analysis by MS were discussed. - Highlights: • Both chiral recognition and determination of enantiomeric excess by mass spectrometry are systematically reviewed. • Classification is based on the behavioral differences of diastereomers formed between chiral analytes and chiral selectors. • Development of ion mobility mass spectrometry for chiral differentiation is covered. • Various methods are highlighted and compared.

  12. Recent Advances in Multinuclear NMR Spectroscopy for Chiral Recognition of Organic Compounds

    Directory of Open Access Journals (Sweden)

    Márcio S. Silva

    2017-02-01

    Full Text Available Nuclear magnetic resonance (NMR is a powerful tool for the elucidation of chemical structure and chiral recognition. In the last decade, the number of probes, media, and experiments to analyze chiral environments has rapidly increased. The evaluation of chiral molecules and systems has become a routine task in almost all NMR laboratories, allowing for the determination of molecular connectivities and the construction of spatial relationships. Among the features that improve the chiral recognition abilities by NMR is the application of different nuclei. The simplicity of the multinuclear NMR spectra relative to 1H, the minimal influence of the experimental conditions, and the larger shift dispersion make these nuclei especially suitable for NMR analysis. Herein, the recent advances in multinuclear (19F, 31P, 13C, and 77Se NMR spectroscopy for chiral recognition of organic compounds are presented. The review describes new chiral derivatizing agents and chiral solvating agents used for stereodiscrimination and the assignment of the absolute configuration of small organic compounds.

  13. Molecularly imprinted polymer based on chemiluminescence imaging for the chiral recognition of dansyl-phenylalanine.

    Science.gov (United States)

    Wang, Li; Zhang, Zhujun; Huang, Lianggao

    2008-03-01

    A new molecularly imprinted polymer (MIP)-chemiluminescence (CL) imaging detection approach towards chiral recognition of dansyl-phenylalanine (Phe) is presented. The polymer microspheres were synthesized using precipitation polymerization with dansyl-L-Phe as template. Polymer microspheres were immobilized in microtiter plates (96 wells) using poly(vinyl alcohol) (PVA) as glue. The analyte was selectively adsorbed on the MIP microspheres. After washing, the bound fraction was quantified based on peroxyoxalate chemiluminescence (PO-CL) analysis. In the presence of dansyl-Phe, bis(2,4,6-trichlorophenyl)oxalate (TCPO) reacted with hydrogen peroxide (H2O2) to emit chemiluminescence. The signal was detected and quantified with a highly sensitive cooled charge-coupled device (CCD). Influencing factors were investigated and optimized in detail. Control experiments using capillary electrophoresis showed that there was no significant difference between the proposed method and the control method at a confidence level of 95%. The method can perform 96 independent measurements simultaneously in 30 min and the limits of detection (LODs) for dansyl-L-Phe and dansyl-D-Phe were 0.025 micromol L(-1) and 0.075 micromol L(-1) (3sigma), respectively. The relative standard deviation (RSD) for 11 parallel measurements of dansyl-L-Phe (0.78 micromol L(-1)) was 8%. The results show that MIP-based CL imaging can become a useful analytical technology for quick chiral recognition.

  14. Attachment of trianglamines to silicon wafers, chiral recognition by chemical force microscopy

    Czech Academy of Sciences Publication Activity Database

    Hlinka, J.; Hodačová, Jana; Raehm, L.; Granier, M.; Ramonda, M.; Durand, J. O.

    2010-01-01

    Roč. 13, č. 4 (2010), s. 481-485 ISSN 1631-0748 R&D Projects: GA MŠk MEB020748 Institutional research plan: CEZ:AV0Z40550506 Keywords : trianglamines * chemical force microscopy * chiral recognition Subject RIV: CC - Organic Chemistry Impact factor: 1.600, year: 2010

  15. Chirality as a tool in nucleic acid recognition: principles and relevance in biotechnology and in medicinal chemistry.

    Science.gov (United States)

    Corradini, Roberto; Sforza, Stefano; Tedeschi, Tullia; Marchelli, Rosangela

    2007-05-05

    The understanding of the interaction of chiral species with DNA or RNA is very important for the development of new tools in biology and of new drugs. Several cases in which chirality is a crucial point in determining the DNA binding mode are reviewed and discussed, with the aim of illustrating how chirality can be considered as a tool for improving the understanding of mechanisms and the effectiveness of nucleic acid recognition. The review is divided into two parts: the former describes examples of chiral species interacting with DNA: intercalators, metal complexes, and groove binders; the latter part is dedicated to chirality in DNA analogs, with discussion of phosphate stereochemistry and chirality of ribose substitutes, in particular of peptide nucleic acids (PNAs) for which a number of works have been published recently dealing with the effect of chirality in DNA recognition. The discussion is intended to show how enantiomeric recognition originates at the molecular level, by exploiting the enormous progresses recently achieved in the field of structural characterization of complexes formed by nucleic acid with their ligands by crystallographic and spectroscopic methods. Examples of application of the DNA binding molecules described and the role of chirality in DNA recognition relevant for biotechnology or medicinal chemistry are reported. (c) 2007 Wiley-Liss, Inc.

  16. Study on the mechanism of chiral recognition with molecularly imprinted polymers

    International Nuclear Information System (INIS)

    Lu Yan; Li Chenxi; Zhang Hesheng; Liu Xiaohang

    2003-01-01

    This study aimed at elucidating the chiral recognition mechanism with molecularly imprinted polymers (MIPs) in aqueous environment. The system used ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA), and 4-L-phenylalanylamino-pyridine (4-L-PheNHPy) as the cross-linking monomer, functional monomer and template, respectively, to assemble the imprinted polymer. A self-assembly mechanism, which includes the pre-organizing functional monomers around template before polymerization process, was proposed. This mechanism was supported by 1 H NMR titration test. Interactions between functional monomer and template were observed using UV-Vis spectroscopy of solutions of these components as well. These studies indicated a 1:2 molecular complex dominantly formed between 4-L-PheNHPy and MAA. Association constant was estimated to be 97,000 M -2 . Based on these results, a model mainly involving two-spot interaction was proposed evolving from our reported concept of exact placement of functional group. Ionic interaction between the primary amino group of 4-L-PheNHPy and carboxylic acid group inside the microcavity on MIPs was believed to play a predominate role in the enantioselectivity as supported by the observation of the relationship between the retention factor of 4-L-PheNHPy and the pH of mobile phase. While thermodynamic study at different pH revealed that, the interaction between the pyridyl group of 4-L-PheNHPy and the carboxylic acid group on the MIPs is also strong, implying that it also plays a profound role in determining the highly chiral selectivity of MIPs

  17. СHIRAL RECOGNITION OF CYSTEINE MOLECULES BY CHIRAL CdSe AND CdS QUANTUM DOTS

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    M. V. Mukhina

    2015-11-01

    Full Text Available Here, we report the investigation of mechanism of chiral molecular recognition of cysteine biomolecules by chiral CdSe and CdS semiconductor nanocrystals. To observe chiral recognition process, we prepared enantioenriched ensembles of the nanocrystals capped with achiral ligand. The enantioenriched samples of intrinsically chiral CdSe quantum dots were prepared by separation of initial racemic mixture of the nanocrystals using chiral phase transfer from chloroform to water driven by L- and D-cysteine. Chiral molecules of cysteine and penicillamine were substituted for achiral molecules of dodecanethiol on the surfaces of CdSe and CdS samples, respectively, via reverse phase transfer from water to chloroform. We estimated an efficiency of the hetero- (d-L or l-D and homocomplexes (l-L formation by comparing the extents of corresponding complexing reactions. Using circular dichroism spectroscopy data we show an ability of nanocrystals enantiomers to discriminate between left-handed and right-handed enantiomers of biomolecules via preferential formation of heterocomplexes. Development of approaches for obtaining chiral nanocrystals via chiral phase transfer offers opportunities for investigation of molecular recognition at the nano/bio interfaces.

  18. Highly efficient induction of chirality in intramolecular

    Science.gov (United States)

    Cossio; Arrieta; Lecea; Alajarin; Vidal; Tovar

    2000-06-16

    Highly stereocontrolled, intramolecular [2 + 2] cycloadditions between ketenimines and imines leading to 1,2-dihydroazeto[2, 1-b]quinazolines have been achieved. The source of stereocontrol is a chiral carbon atom adjacent either to the iminic carbon or nitrogen atom. In the first case, the stereocontrol stems from the preference for the axial conformer in the first transition structure. In the second case, the origin of the stereocontrol lies on the two-electron stabilizing interaction between the C-C bond being formed and the sigma orbital corresponding to the polar C-X bond, X being an electronegative atom. These models can be extended to other related systems for predicting the stereochemical outcome in this intramolecular reaction.

  19. Synthesis and anion recognition properties of shape-persistent binaphthyl-containing chiral macrocyclic amides

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    Marco Caricato

    2012-06-01

    Full Text Available We report on the synthesis and characterization of novel shape-persistent, optically active arylamide macrocycles, which can be obtained using a one-pot methodology. Resolved, axially chiral binol scaffolds, which incorporate either methoxy or acetoxy functionalities in the 2,2' positions and carboxylic functionalities in the external 3,3' positions, were used as the source of chirality. Two of these binaphthyls are joined through amidation reactions using rigid diaryl amines of differing shapes, to give homochiral tetraamidic macrocycles. The recognition properties of these supramolecular receptors have been analyzed, and the results indicate a modulation of binding affinities towards dicarboxylate anions, with a drastic change of binding mode depending on the steric and electronic features of the functional groups in the 2,2' positions.

  20. Fluorescence recognition of chiral amino alcohols by using a novel ionic liquid sensor.

    Science.gov (United States)

    Cai, Pengfei; Wu, Datong; Zhao, Xiaoyong; Pan, Yuanjiang

    2017-08-07

    A novel task-specific ionic liquid derived from l-phenylalaninol was prepared as an enantioselective fluorescent sensor for the first time. Fluorescent chiral ionic liquid 1 (FCIL1) is found to exhibit highly enantioselective fluorescence enhancements toward both aromatic and non-aromatic chiral amino alcohols. When (S)-FCIL1 was treated with the enantiomers of phenylalaninol, a great fluorescence enhancement at 349 nm could be observed and the value of the enantiomeric fluorescence difference (ef) is 5.92. This demonstrated that the chiral sensor (S)-FCIL1 exhibited an excellent enantioselective response behaviour to d-phenylalaninol. Besides that, both the fluorescence intensity at 349 nm (I 349 ) and the ratio of I 349 to I 282 depend linearly on the concentration of amino alcohols. Both the concentration and the enantiomeric composition could be determined by using the chiral ionic liquid. Differently, the sensor treated with the enantiomers of 2-amino-1-butanol showed an opposite result: the fluorescence intensity of the S-enantiomer is higher than that of the R-enantiomer. Furthermore, the size of the substituents on the chiral carbon might be important for the enantioselective fluorescent response.

  1. A colorimetric chiral sensor based on chiral crown ether for the recognition of the two enantiomers of primary amino alcohols and amines.

    Science.gov (United States)

    Cho, Eun Na Rae; Li, Yinan; Kim, Hee Jin; Hyun, Myung Ho

    2011-04-01

    A new colorimetric chiral sensor material consisting of three different functional sites such as chromophore (2,4-dinitrophenylazophenol dye), binding site (crown ether), and chiral barrier (3,3'-diphenyl-1,1'-binaphthyl group) was prepared and applied to the recognition of the two enantiomers of primary amino alcohols and amines. Among five primary amino alcohols and two primary amines tested, the two enantiomers of phenylalaninol show the highest difference in the absorption maximum wavelength (Δλ(max)=43.5 nm) and in the association constants (K(S)/K(R)=2.51) upon complexation with the colorimetric chiral sensor material and, consequently, the two enantiomers of phenylalaninol were clearly distinguished from each other by the color difference. Copyright © 2010 Wiley-Liss, Inc.

  2. An aptamer-based fluorescence bio-sensor for chiral recognition of arginine enantiomers.

    Science.gov (United States)

    Yuan, Haiyan; Huang, Yunmei; Yang, Jidong; Guo, Yuan; Zeng, Xiaoqing; Zhou, Shang; Cheng, Jiawei; Zhang, Yuhui

    2018-07-05

    In this study, a novel aptamer - based fluorescence bio-sensor (aptamer-AuNps) was developed for chiral recognition of arginine (Arg) enantiomers based on aptamer and gold nanoparticles (AuNps). Carboxyfluorescein (FAM) labeled aptamers (Apt) were absorbed on AuNps and their fluorescence intensity could be significantly quenched by AuNps based on fluorescence resonance energy transfer (FRET). Once d-Arg or l-Arg were added into the above solution, the aptamer specifically bind to Arg enantiomers and released from AuNps, so the fluorescence intensity of d-Arg system and l-Arg system were all enhanced. The affinity of Apt to l-Arg is tighter to d-Arg, so the enhanced fluorescence signals of l-Arg system was stronger than d-Arg system. What's more, the enhanced fluorescence were directly proportional to the concentration of d-Arg and l-Arg ranging from 0-300 nM and 0-400 nM with related coefficients of 0.9939 and 0.9952, respectively. Furthermore, the method was successfully applied to detection l-Arg in human urine samples with satisfactory results. Eventually, a simple "OR" logic gate with d-Arg &l-Arg as inputs and AuNps aggregation state as outputs was fabricated, which can help us understand the chiral recognition process deeply. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Self-Assembled Core-Satellite Gold Nanoparticle Networks for Ultrasensitive Detection of Chiral Molecules by Recognition Tunneling Current.

    Science.gov (United States)

    Zhang, Yuanchao; Liu, Jingquan; Li, Da; Dai, Xing; Yan, Fuhua; Conlan, Xavier A; Zhou, Ruhong; Barrow, Colin J; He, Jin; Wang, Xin; Yang, Wenrong

    2016-05-24

    Chirality sensing is a very challenging task. Here, we report a method for ultrasensitive detection of chiral molecule l/d-carnitine based on changes in the recognition tunneling current across self-assembled core-satellite gold nanoparticle (GNP) networks. The recognition tunneling technique has been demonstrated to work at the single molecule level where the binding between the reader molecules and the analytes in a nanojunction. This process was observed to generate a unique and sensitive change in tunneling current, which can be used to identify the analytes of interest. The molecular recognition mechanism between amino acid l-cysteine and l/d-carnitine has been studied with the aid of SERS. The different binding strength between homo- or heterochiral pairs can be effectively probed by the copper ion replacement fracture. The device resistance was measured before and after the sequential exposures to l/d-carnitine and copper ions. The normalized resistance change was found to be extremely sensitive to the chirality of carnitine molecule. The results suggested that a GNP networks device optimized for recognition tunneling was successfully built and that such a device can be used for ultrasensitive detection of chiral molecules.

  4. Optical Chirality in Nonlinear Optics: Application to High Harmonic Generation.

    Science.gov (United States)

    Neufeld, Ofer; Cohen, Oren

    2018-03-30

    Optical chirality (OC)-one of the fundamental quantities of electromagnetic fields-corresponds to the instantaneous chirality of light. It has been utilized for exploring chiral light-matter interactions in linear optics, but has not yet been applied to nonlinear processes. Motivated to explore the role of OC in the generation of helically polarized high-order harmonics and attosecond pulses, we first separate the OC of transversal and paraxial beams to polarization and orbital terms. We find that the polarization-associated OC of attosecond pulses corresponds approximately to that of the pump in the quasimonochromatic case, but not in the multichromatic pump cases. We associate this discrepancy with the fact that the polarization OC of multichromatic pumps vary rapidly in time along the optical cycle. Thus, we propose new quantities, noninstantaneous polarization-associated OC, and time-scale-weighted polarization-associated OC, and show that these quantities link the chirality of multichromatic pumps and their generated attosecond pulses. The presented extension to OC theory should be useful for exploring various nonlinear chiral light-matter interactions. For example, it stimulates us to propose a tricircular pump for generation of highly elliptical attosecond pulses with a tunable ellipticity.

  5. Optical Chirality in Nonlinear Optics: Application to High Harmonic Generation

    Science.gov (United States)

    Neufeld, Ofer; Cohen, Oren

    2018-03-01

    Optical chirality (OC)—one of the fundamental quantities of electromagnetic fields—corresponds to the instantaneous chirality of light. It has been utilized for exploring chiral light-matter interactions in linear optics, but has not yet been applied to nonlinear processes. Motivated to explore the role of OC in the generation of helically polarized high-order harmonics and attosecond pulses, we first separate the OC of transversal and paraxial beams to polarization and orbital terms. We find that the polarization-associated OC of attosecond pulses corresponds approximately to that of the pump in the quasimonochromatic case, but not in the multichromatic pump cases. We associate this discrepancy with the fact that the polarization OC of multichromatic pumps vary rapidly in time along the optical cycle. Thus, we propose new quantities, noninstantaneous polarization-associated OC, and time-scale-weighted polarization-associated OC, and show that these quantities link the chirality of multichromatic pumps and their generated attosecond pulses. The presented extension to OC theory should be useful for exploring various nonlinear chiral light-matter interactions. For example, it stimulates us to propose a tricircular pump for generation of highly elliptical attosecond pulses with a tunable ellipticity.

  6. Disoriented Chiral Condensates in High-Energy Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Randrup, Jorgen

    2000-10-18

    This brief lecture series discusses how our current understanding of chiral symmetry may be tested more globally in high-energy nuclear collisions by suitable extraction of pionic observables. After briefly recalling the general features of chiral symmetry, we focus on the SU(2) linear sigma model and show how a semi-classical mean-field treatment makes it possible to calculate its statistical properties, including the chiral phase diagram. Subsequently, we consider scenarios of relevance to high-energy collisions and discuss the features of the ensuing non-equilibrium dynamics and the associated characteristic signals. Finally, we illustrate how the presence of vacuum fluctuations or the inclusion of strangeness may affect the results quantitatively.

  7. Increments to chiral recognition facilitating enantiomer separations of chiral acids, bases, and ampholytes using Cinchona-based zwitterion exchanger chiral stationary phases.

    Science.gov (United States)

    Wernisch, Stefanie; Pell, Reinhard; Lindner, Wolfgang

    2012-07-01

    The intramolecular distances of anion and cation exchanger sites of zwitterionic chiral stationary phases represent potential tuning sites for enantiomer selectivity. In this contribution, we investigate the influence of alkanesulfonic acid chain length and flexibility on enantiomer separations of chiral acids, bases, and amphoteric molecules for six Cinchona alkaloid-based chiral stationary phases in comparison with structurally related anion and cation exchangers. Employing polar-organic elution conditions, we observed an intramolecular counterion effect for acidic analytes which led to reduced retention times but did not impair enantiomer selectivities. Retention of amphoteric analytes is based on simultaneous double ion pairing of their charged functional groups with the acidic and basic sites of the zwitterionic selectors. A chiral center in the vicinity of the strong cation exchanger site is vital for chiral separations of bases. Sterically demanding side chains are beneficial for separations of free amino acids. Enantioseparations of free (un-derivatized) peptides were particularly successful in stationary phases with straight-chain alkanesulfonic acid sites, pointing to a beneficial influence of more flexible moieties. In addition, we observed pseudo-enantiomeric behavior of quinine and quinidine-derived chiral stationary phases facilitating reversal of elution orders for all analytes. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 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.

  9. High electron thermal conductivity of chiral carbon nanotubes

    International Nuclear Information System (INIS)

    Mensah, S.Y.; Allotey, F.K.A.; Nkrumah, George; Mensah, N.G.

    2003-11-01

    Solving the Boltzmann kinetic equation with energy dispersion relation obtained in the tight binding approximation, the carrier thermal conductivity κ e of a chiral carbon nanotube (CCNT) was determined. The dependence of κ e on temperature T, chiral geometric angle φ h and overlap integrals Δ z and Δ s were obtained. The results were numerically analysed. Unusually high values of κ e were observed suggesting that ne is nontrivial in the calculation of the thermal conductivity κ of CCNT. More interestingly we noted also that at 104 K and for Δ z and Δ s values of 0.020 eV and 0.0150 eV respectively the κ e value is about 41000 W/mK as reported for a 99.9% pure 12 C crystal. We predict that the electron thermal conductivity of CCNT should exceed 200,000 W/mK at ∼ 80 K. (author)

  10. Enantioselective Collision-Activated Dissociation of Gas-Phase Tryptophan Induced by Chiral Recognition of Protonated l-Alanine Peptides

    Science.gov (United States)

    Fujihara, Akimasa; Matsuyama, Hiroki; Tajiri, Michiko; Wada, Yoshinao; Hayakawa, Shigeo

    2017-06-01

    Enantioselective dissociation in the gas phase is important for enantiomeric enrichment and chiral transmission processes in molecular clouds regarding the origin of homochirality in biomolecules. Enantioselective collision-activated dissociation (CAD) of tryptophan (Trp) and the chiral recognition ability of l-alanine peptides ( l-Ala n ; n = 2-4) were examined using a linear ion trap mass spectrometer. CAD spectra of gas-phase heterochiral H+( d-Trp)( l-Ala n ) and homochiral H+( l-Trp)( l-Ala n ) noncovalent complexes were obtained as a function of the peptide size n. The H2O-elimination product was observed in CAD spectra of both heterochiral and homochiral complexes for n = 2 and 4, and in homochiral H+( l-Trp)( l-Ala3), indicating that the proton is attached to the l-alanine peptide, and H2O loss occurs from H+( l-Ala n ) in the noncovalent complexes. H2O loss did not occur in heterochiral H+( d-Trp)( l-Ala3), where NH3 loss and (H2O + CO) loss were the primary dissociation pathways. In heterochiral H+( d-Trp)( l-Ala3), the protonation site is the amino group of d-Trp, and NH3 loss and (H2O + CO) loss occur from H+( d-Trp). l-Ala peptides recognize d-Trp through protonation of the amino group for peptide size n = 3. NH3 loss and (H2O + CO) loss from H+( d-Trp) proceeds via enantioselective CAD in gas-phase heterochiral H+( d-Trp)( l-Ala3) at room temperature, whereas l-Trp dissociation was not observed in homochiral H+( l-Trp)( l-Ala3). These results suggest that enantioselective dissociation induced by chiral recognition of l-Ala peptides through protonation could play an important role in enantiomeric enrichment and chiral transmission processes of amino acids.

  11. Chiral recognition of naproxen enantiomers based on fluorescence quenching of bovine serum albumin-stabilized gold nanoclusters

    Science.gov (United States)

    Jafari, Marzieh; Tashkhourian, Javad; Absalan, Ghodratollah

    2017-10-01

    A simple, fast and green method for chiral recognition of S- and R-naproxen has been introduced. The method was based on quenching of the fluorescence intensity of bovine serum albumin-stabilized gold nanoclusters in the presence of naproxen enantiomers. The quenching intensity in the presence of S-naproxen was higher than R-naproxen when phosphate buffer solution at pH 7.0 was used. The chiral recognition occurred due to steric effect between bovine serum albumin conformation and naproxen enantiomers. Two linear determination range were established as 7.4 × 10-7-9.1 × 10-6 and 9.1 × 10-6-3.1 × 10-5 mol L-1 for both enantiomers and detection limits of 7.4 × 10-8 mol L- 1 and 9.5 × 10-8 mol L-1 were obtained for S- and R-naproxen, respectively. The developed method showed good repeatability and reproducibility for the analysis of a synthetic sample. To make the procedure applicable to biological samples, the removal of heavy metals from the sample is suggested before any analytical attempt.

  12. High-performance liquid chromatographic separations of stereoisomers of chiral basic agrochemicals with polysaccharide-based chiral columns and polar organic mobile phases.

    Science.gov (United States)

    Matarashvili, Iza; Shvangiradze, Iamze; Chankvetadze, Lali; Sidamonidze, Shota; Takaishvili, Nino; Farkas, Tivadar; Chankvetadze, Bezhan

    2015-12-01

    The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The combination of high Q factor and chirality in twin cavities and microcavity chain

    Science.gov (United States)

    Song, Qinghai; Zhang, Nan; Zhai, Huilin; Liu, Shuai; Gu, Zhiyuan; Wang, Kaiyang; Sun, Shang; Chen, Zhiwei; Li, Meng; Xiao, Shumin

    2014-01-01

    Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities. PMID:25262881

  14. High-Throughput Genetic Analysis and Combinatorial Chiral Separations Based on Capillary Electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Wenwan [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Capillary electrophoresis (CE) offers many advantages over conventional analytical methods, such as speed, simplicity, high resolution, low cost, and small sample consumption, especially for the separation of enantiomers. However, chiral method developments still can be time consuming and tedious. They designed a comprehensive enantioseparation protocol employing neutral and sulfated cyclodextrins as chiral selectors for common basic, neutral, and acidic compounds with a 96-capillary array system. By using only four judiciously chosen separation buffers, successful enantioseparations were achieved for 49 out of 54 test compounds spanning a large variety of pKs and structures. Therefore, unknown compounds can be screened in this manner to identify optimal enantioselective conditions in just one rn. In addition to superior separation efficiency for small molecules, CE is also the most powerful technique for DNA separations. Using the same multiplexed capillary system with UV absorption detection, the sequence of a short DNA template can be acquired without any dye-labels. Two internal standards were utilized to adjust the migration time variations among capillaries, so that the four electropherograms for the A, T, C, G Sanger reactions can be aligned and base calling can be completed with a high level of confidence. the CE separation of DNA can be applied to study differential gene expression as well. Combined with pattern recognition techniques, small variations among electropherograms obtained by the separation of cDNA fragments produced from the total RNA samples of different human tissues can be revealed. These variations reflect the differences in total RNA expression among tissues. Thus, this Ce-based approach can serve as an alternative to the DNA array techniques in gene expression analysis.

  15. Computer-Assisted Design and Synthetic Applications of Chiral Enol Borinates: Novel, Highly Enantioselective Aldol Reagents

    Directory of Open Access Journals (Sweden)

    Gennari Cesare

    1998-01-01

    Full Text Available We have recently described the development of a quantitative transition state model for the prediction of stereoselectivity in the boron-mediated aldol reaction. This model provides qualitative insights into the factors contributing to the stereochemical outcome of a variety of reactions of synthetic importance. The force field model was used to assist the design and preparation of new chiral boron ligands derived from menthone. The chiral boron enolates were employed in various stereoselective processes, including the addition to chiral aldehydes and the reagent-controlled total synthesis of (3S,4S-statine. The chiral enolates derived from alpha-halo and alpha-oxysubstituted thioacetates were added to aldehydes and imines. Addition to imines leads to the enantioselective synthesis of chiral aziridines, a formal total synthesis of (+-thiamphenicol, and a new highly efficient synthesis of the paclitaxel (taxol® C-13 side-chain and taxol semisynthesis from baccatin III. The stereochemical outcome of the addition to imines was rationalised with the aid of computational studies. Enantioselective addition reactions of the chiral boron enolate derived from thioacetate have successfully been applied to solid phase bound aldehydes to give aldol products in comparable yields and enantioselectivities to the usual solution conditions.

  16. Chiral recognition of phenylglycinol enantiomers based on N-acetyl-L-cysteine capped CdTe quantum dots in the presence of Ag+

    Science.gov (United States)

    Guo, Yuan; Zeng, Xiaoqing; Yuan, Haiyan; Huang, Yunmei; Zhao, Yanmei; Wu, Huan; Yang, Jidong

    2017-08-01

    In this study, a novel method for chiral recognition of phenylglycinol (PG) enantiomers was proposed. Firstly, water-soluble N-acetyl-L-cysteine (NALC)-capped CdTe quantum dots (QDs) were synthesized and experiment showed that the fluorescence intensity of the reaction system slightly enhancement when added PG enantiomers to NALC-capped CdTe quantum dots (QDs), but the R-PG and S-PG could not be distinguished. Secondly, when there was Ag+ presence in the reaction system, the experiment result was extremely interesting, the PG enantiomers cloud make NALC-capped CdTe QDs produce different fluorescence signal, in which the fluorescence of S-PG + Ag+ + NALC-CdTe system was significantly enhanced, and the fluorescence of R-PG + Ag+ + NALC-CdTe system was markedly decreased. Thirdly, all the enhanced and decreased of the fluorescence intensity were directly proportional to the concentration of R-PG and S-PG in the linearly range 10- 5-10- 7 mol·L- 1, respectively. So, the new method for simultaneous determination of the PG enantiomers was built too. The experiment result of the method was satisfactory with the detection limit of PG can reached 10- 7 mol·L- 1 and the related coefficient of S-PG and R-PG are 0.995 and 0.980, respectively. The method was highly sensitive, selective and had wider detection range compared with other methods.

  17. Pattern recognition in high energy physics

    International Nuclear Information System (INIS)

    Tenner, A.G.

    1980-01-01

    In high energy physics experiments tracks of elementary particles are recorded by different types of equipment. Coordinates of points of these tracks have to be measured for the geometrical reconstruction and the further analysis of the observed events. Pattern recognition methods may facilitate the detection of tracks or whole events and the separation of relevant from non-relevant information. They may also serve for the automation of measurement. Generally, all work is done by digital computation. In a bubble chamber tracks appear as strings of vapour bubbles that can be recorded photographically. Two methods of pattern recognition are discussed. The flying spot digitizer encodes the pattern on the photograph into point coordinates in the memory of a computer. The computer carries out the pattern recognition procedure entirely on the basis of the stored information. Cathode ray instruments scan the photograph by means of a computer steered optical device. Data acquisition from the film is performed in a feedback loop of the computation. In electronic experimental equipment tracks are defined by the spacial distribution of hits of counters (wire counters, scintillation counters, spark chambers). Pattern recognition is generally performed in various stages both by on-line and off-line equipment. Problems in the data handling arise both from the great abundance of data and from the time limits imposed on the on-line computation by high measuring rates. The on-line computation is carried out by hardwired logic, small computers, and to an increasing extent by microprocessors. (Auth.)

  18. The chiral anomaly of quantum chromodynamics at high temperatures. Lattice investigation of the overlap Dirac spectrum

    International Nuclear Information System (INIS)

    Dick, Viktor

    2016-04-01

    In this work, the spectrum of the overlap Dirac operator has been computed and analyzed on configurations that had been created using highly improved staggered quarks. Although the overlap operator is expensive to compute, it has the advantage that it fully implements chiral symmetry in the same way as the continuum QCD Dirac operator even at finite lattice spacings. This opened the possibility to investigate chiral aspects of QCD and, in particular, the question if the axial anomaly is suppressed at the chiral transition temperature T c . The obtained results indicate that the axial anomaly is still present at T c and even at 1.5 T c as evidenced by a splitting in the integrated pion and delta susceptibilities. The spectrum shows a peak in the near-zero region consisting of zero modes and pairs of near-zero modes. The breaking of the axial symmetry was identified as being caused by these infrared modes. It was discussed how this infrared contribution might change in the thermodynamic, continuum, and chiral limits. The obtained data supports the expectation that the peak becomes narrower with decreasing quark masses, resulting in a Dirac-delta peak in the chiral limit. The area under the peak was found to decrease with decreasing lattice spacing, so in order to resolve how much of it survives the continuum limit further investigations are needed, in particular ones where already for the generation of gauge configurations chiral fermions are used. The infrared modes were investigated and found to be highly localized, supporting the picture of QCD at high temperatures as a dilute instanton gas. The instantons were found to have an average size of 0.239(4) fm and a density of 0.154(5) fm -4 at 1.5 T c . Near-zero modes were found to be induced by instanton-anti-instanton molecules, which are weakly bound. At temperatures closer to T c , this picture becomes more complicated but these features sometimes still can be recognized. In conclusion, in QCD at temperatures

  19. Chiral Recognition in Molecular and Macromolecular Pairs of(S)- and (R)- 1-Cyano-2-Methylpropyl 4’((4-(8-Vinyloxyoctyloxy)Benzoyl) Biphenyl-4-Carboxylate Enantiomers

    Science.gov (United States)

    1994-06-30

    above please provide a graphical abstract of the paper ar, return it to the Editorial Office as soon as possible. 4oeg0 o F-99S or TS A& I DTI•’ I J. u1...TCLSICAON 2.LIMITATION OF ABSTRAC •F oFPORT OF THIS PAGE OF ABSTRACT . unclass ified Graphical Abstracts for Perkin Txans. 1 Example TITLE GRAPHICAL ... ABSTRACT AUTHORS’ N AMES Template (S)-II Chiral recognition in molecular and . -- macromolecular pairs of (S)- and -- (R)-i-cyano-2-methyipropyl 4’-{[4

  20. Molecular self assembly and chiral recognition of copper octacyanophthalocyanine on Au(111): Interplay of intermolecular and molecule-substrate interactions.

    Science.gov (United States)

    Sk, Rejaul; Dhara, Barun; Miller, Joel; Deshpande, Aparna

    Submolecular resolution scanning tunneling microscopy (STM) of copper octacyanophthalocyanine, CuPc(CN)8, at 77 K demonstrates that these achiral molecules form a two dimensional (2D) tetramer-based self-assembly upon evaporation onto an atomically flat Au(111) substrate. They assemble in two different structurally chiral configurations upon adsorption on Au(111). Scanning tunneling spectroscopy (STS),acquired at 77 K, unveils the HOMO and LUMO energy levels of this self-assembly. Voltage dependent STM images show that each molecule in both the structurally chiral configurations individually becomes chiral by breaking the mirror symmetry due to the enhanced intermolecular dipolar coupling interaction at the LUMO energy while the individual molecules remain achiral at the HOMO energy and within the HOMO-LUMO gap. At the LUMO energy, the handedness of the each chiral molecule is decided by the direction of the dipolar coupling interaction in the tetramer unit cell. This preference for LUMO energy indicates that this chirality is purely electronic in nature and it manifests on top of the organizational chirality that is present in the self-assembly independent of the orbital energy. Supported by IISER Pune and DAE-BRNS, India (Project No. 2011/20/37C/17/BRNS).

  1. Capillary electrophoretic enantioseparation of basic drugs using a new single-isomer cyclodextrin derivative and theoretical study of the chiral recognition mechanism.

    Science.gov (United States)

    Liu, Yongjing; Deng, Miaoduo; Yu, Jia; Jiang, Zhen; Guo, Xingjie

    2016-05-01

    A novel single-isomer cyclodextrin derivative, heptakis {2,6-di-O-[3-(1,3-dicarboxyl propylamino)-2-hydroxypropyl]}-β-cyclodextrin (glutamic acid-β-cyclodextrin) was synthesized and used as a chiral selector in capillary electrophoresis for the enantioseparation of 12 basic drugs, including terbutaline, clorprenaline, tulobuterol, clenbuterol, procaterol, carvedilol, econazole, miconazole, homatropine methyl bromide, brompheniramine, chlorpheniramine and pheniramine. The primary factors affecting separation efficiency, which include the background electrolyte pH, the concentration of glutamic acid-β-cyclodextrin and phosphate buffer concentration, were investigated. Satisfactory enantioseparations were obtained using an uncoated fused-silica capillary of 50 cm (effective length 40 cm) × 50 μm id with 120 mM phosphate buffer (pH 2.5-4.0) containing 0.5-4.5 mM glutamic acid-β-cyclodextrin as background electrolyte. A voltage of 20 kV was applied and the capillary temperature was kept at 20°C. The results proved that glutamic acid-β-cyclodextrin was an effective chiral selector for studied 12 basic drugs. Moreover, the possible chiral recognition mechanism of brompheniramine, chlorpheniramine and pheniramine on glutamic acid-β-cyclodextrin was investigated using the semi-empirical Parametric Method 3. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Chiral pyrrolidinium salts derived from menthol as precursor – synthesis and properties

    Directory of Open Access Journals (Sweden)

    Janus Ewa

    2017-09-01

    Full Text Available Six new chiral pyrolidinium salts with chiral substituent at quaternary nitrogen atom were synthesized with high overall yields from (--menthol as cheap chiral precursor and were identified by NMR and HRMS spectroscopy. It was shown that anion type had the effect on chemical shift of protons adjacent to quaternary nitrogen atom and physical properties of these salts. Salts with NTf2 or NPf2 were in a liquid state at room temperature and characterized with the highest thermal stability among others. Furthermore, chiral ionic liquid with NTf2 anion was used as solvent in Diels-Alder reaction and gave higher yield and stereoselectivity than in ionic liquids with achiral cations. Synthesized chiral salts have the potential as chiral solvents in synthesis and auxiliaries in analytical methods to improve chiral recognition.

  3. Enantioselective recognition of mandelic acid by a 3,6-dithiophen-2-yl-9H-carbazole-based chiral fluorescent bisboronic acid sensor.

    Science.gov (United States)

    Wu, Yubo; Guo, Huimin; James, Tony D; Zhao, Jianzhang

    2011-07-15

    We have prepared chiral fluorescent bisboronic acid sensors with 3,6-dithiophen-2-yl-9H-carbazole as the fluorophore. The thiophene moiety was used to extend the π-conjugation framework of the fluorophore in order to red-shift the fluorescence emission and, at the same time, to enhance the novel process where the fluorophore serves as the electron donor of the photoinduced electron transfer process (d-PET) of the boronic acid sensors; i.e., the background fluorescence of the sensor 1 at acidic pH is weaker compared to that at neutral or basic pH, in stark contrast to the typical a-PET boronic acid sensors (where the fluorophore serves as the electron acceptor of the photoinduced electron transfer process). The benefit of the d-PET boronic acid sensors is that the recognition of the hydroxylic acids can be achieved at acidic pH. We found that the thiophene moiety is an efficient π-conjugation linker and electron donor; as a result, the d-PET contrast ratio of the sensors upon variation of the pH is improved 10-fold when compared to the previously reported d-PET sensors without the thiophene moiety. Enantioselective recognition of tartaric acid was achieved at acid pH, and the enantioselectivity (total response K(D)I(F)(D)/K(L)I(F)(L)) is 3.3. The fluorescence enhancement (I(F)(Sample)/I(F)(Blank)) of sensor 1 upon binding with tartaric acid is 3.5-fold at pH 3.0. With the fluorescent bisboronic acid sensor 1, enantioselective recognition of mandelic acid was achieved for the first time. To the best of our knowledge, this is the first time that the mandelic acid has been enantioselectively recognized using a chiral fluorescent boronic acid sensor. Chiral monoboronic acid sensor 2 and bisboronic acid sensor 3 without the thiophene moiety failed to enantioselectively recognize mandelic acid. Our findings with the thiophene-incorporated boronic acid sensors will be important for the design of d-PET fluorescent sensors for the enantioselective recognition of

  4. Evaluation of the chiral recognition properties as well as the column performance of four chiral stationary phases based on cellulose (3,5-dimethylphenylcarbamate) by parallel HPLC and SFC.

    Science.gov (United States)

    Nelander, Hanna; Andersson, Shalini; Ohlén, Kristina

    2011-12-30

    The performance of four commercially available cellulose tris(3,5-dimethylphenylcarbamate) based chiral stationary phases (CSPs) was evaluated with parallel high performance liquid chromatography (HPLC) and super critical fluid chromatography (SFC). Retention, enantioselectivity, resolution and efficiency were compared for a set of neutral, basic and acidic compounds having different physico-chemical properties by using different mobile phase conditions. Although the chiral selector is the same in all the four CSPs, a large difference in the ability to retain and resolve enantiomers was observed under the same chromatographic conditions. We believe that this is mainly due to differences in the silica matrix and immobilization techniques used by the different vendors. An extended study of metoprolol and structure analogues gave a deeper understanding of the accessibility of the chiral discriminating interactions and its impact on the resolution of the racemic compounds on the four CSPs studied. Also, a clear difference in enantioselectivity is observed between SFC and LC mode, hydrogen bonding was found to play an important role in the differential binding of the enantiomers to the CSPs. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Industrial-scale separation of high-purity single-chirality single-wall carbon nanotubes for biological imaging

    Science.gov (United States)

    Yomogida, Yohei; Tanaka, Takeshi; Zhang, Minfang; Yudasaka, Masako; Wei, Xiaojun; Kataura, Hiromichi

    2016-01-01

    Single-chirality, single-wall carbon nanotubes are desired due to their inherent physical properties and performance characteristics. Here, we demonstrate a chromatographic separation method based on a newly discovered chirality-selective affinity between carbon nanotubes and a gel containing a mixture of the surfactants. In this system, two different selectivities are found: chiral-angle selectivity and diameter selectivity. Since the chirality of nanotubes is determined by the chiral angle and diameter, combining these independent selectivities leads to high-resolution single-chirality separation with milligram-scale throughput and high purity. Furthermore, we present efficient vascular imaging of mice using separated single-chirality (9,4) nanotubes. Due to efficient absorption and emission, blood vessels can be recognized even with the use of ∼100-fold lower injected dose than the reported value for pristine nanotubes. Thus, 1 day of separation provides material for up to 15,000 imaging experiments, which is acceptable for industrial use. PMID:27350127

  6. Lipase-catalyzed highly enantioselective kinetic resolution of boron-containing chiral alcohols.

    Science.gov (United States)

    Andrade, Leandro H; Barcellos, Thiago

    2009-07-16

    The first application of enzymes as catalysts to obtain optically pure boron compounds is described. The kinetic resolution of boron-containing chiral alcohols via enantioselective transesterification catalyzed by lipases was studied. Aromatic, allylic, and aliphatic secondary alcohols containing a boronate ester or boronic acid group were resolved by lipase from Candida antartica (CALB), and excellent E values (E > 200) and high enantiomeric excesses (up to >99%) of both remaining substrates and acetylated product were obtained.

  7. Human face recognition ability is specific and highly heritable.

    Science.gov (United States)

    Wilmer, Jeremy B; Germine, Laura; Chabris, Christopher F; Chatterjee, Garga; Williams, Mark; Loken, Eric; Nakayama, Ken; Duchaine, Bradley

    2010-03-16

    Compared with notable successes in the genetics of basic sensory transduction, progress on the genetics of higher level perception and cognition has been limited. We propose that investigating specific cognitive abilities with well-defined neural substrates, such as face recognition, may yield additional insights. In a twin study of face recognition, we found that the correlation of scores between monozygotic twins (0.70) was more than double the dizygotic twin correlation (0.29), evidence for a high genetic contribution to face recognition ability. Low correlations between face recognition scores and visual and verbal recognition scores indicate that both face recognition ability itself and its genetic basis are largely attributable to face-specific mechanisms. The present results therefore identify an unusual phenomenon: a highly specific cognitive ability that is highly heritable. Our results establish a clear genetic basis for face recognition, opening this intensively studied and socially advantageous cognitive trait to genetic investigation.

  8. A highly sensitive multiplasmonic sensor using hyperbolic chiral sculptured thin films

    Science.gov (United States)

    Abbas, Farhat; Faryad, Muhammad

    2017-11-01

    Surface plasmon-polariton (SPP) waves guided by an interface of a metal and a hyperbolic chiral sculptured thin film (STF) were theoretically investigated for optical sensing of an analyte. The chiral STF was infiltrated with the analyte to be sensed, and the resulting change in the incidence angle of excitation of the SPP waves in the prism-coupled configuration was computed. The results indicated the potential of this configuration for a plasmonic sensor with sensitivity up to 6000 degrees per refractive index units of the infiltrating fluid in the angular investigation scheme, with multiple SPP waves of the same frequency but different phase speeds, spatial profiles, and sensitivities. The enhancement in the sensitivity is attributed to the high field strength of the SPP waves near the interface. A multiplasmonic sensor is advantageous because of its potential for higher confidence in the measurement of the same analyte.

  9. Chirality in molecular collision dynamics

    Science.gov (United States)

    Lombardi, Andrea; Palazzetti, Federico

    2018-02-01

    Chirality is a phenomenon that permeates the natural world, with implications for atomic and molecular physics, for fundamental forces and for the mechanisms at the origin of the early evolution of life and biomolecular homochirality. The manifestations of chirality in chemistry and biochemistry are numerous, the striking ones being chiral recognition and asymmetric synthesis with important applications in molecular sciences and in industrial and pharmaceutical chemistry. Chiral discrimination phenomena, due to the existence of two enantiomeric forms, very well known in the case of interaction with light, but still nearly disregarded in molecular collision studies. Here we review some ideas and recent advances about the role of chirality in molecular collisions, designing and illustrating molecular beam experiments for the demonstration of chiral effects and suggesting a scenario for a stereo-directional origin of chiral selection.

  10. Rhodium/chiral diene-catalyzed asymmetric 1,4-addition of arylboronic acids to chromones: a highly enantioselective pathway for accessing chiral flavanones.

    Science.gov (United States)

    He, Qijie; So, Chau Ming; Bian, Zhaoxiang; Hayashi, Tamio; Wang, Jun

    2015-03-01

    Chromone has been noted to be one of the most challenging substrates in the asymmetric 1,4-addition of α,β-unsaturated carbonyl compounds. By employing the rhodium complex associated with a chiral diene ligand, (R,R)-Ph-bod*, the 1,4-addition of a variety of arylboronic acids was realized to give high yields of the corresponding flavanones with excellent enantioselectivities (≥97% ee, 99% ee for most substrates). Ring-opening side products, which would lead to erosion of product enantioselectivity, were not observed under the stated reaction conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Application of cyanuric chloride-based six new chiral derivatizing reagents having amino acids and amino acid amides as chiral auxiliaries for enantioresolution of proteinogenic amino acids by reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Bhushan, Ravi; Dixit, Shuchi

    2012-04-01

    Six dichloro-s-triazine (DCT) reagents having L-Leu, D-Phg, L-Val, L-Met, L-Ala and L-Met-NH(2) as chiral auxiliaries in cyanuric chloride were introduced for enantioseparation of 13 proteinogenic amino acids. Four other DCTs and six monochloro-s-triazine (MCT) reagents having amino acid amides as chiral auxiliaries were also synthesized. These 16 chiral derivatizing reagents (CDRs) were used for synthesis of diastereomers of all the 13 analytes using microwave irradiation, which were resolved by reversed-phase high-performance liquid chromatography (RP-HPLC) using C18 column and gradient eluting mixture of aqueous TFA and acetonitrile with UV detection at 230 nm. It required only 60-90 s for derivatization using microwave irradiation. Better resolution and lower retention times were observed for the diastereomers prepared with CDRs having amino acids as chiral auxiliaries as compared to counterparts prepared with reagents having amino acid amides as chiral auxiliaries. As the best resolution of all the 13 analytes was observed for their diastereomers prepared using the DCT reagent having L-Leu as chiral auxiliary, this CDR was further employed for derivatization of Lys, Tyr, His and Arg followed by RP-HPLC analysis of resulting diastereomers. The results are discussed in light of acid and amide groups of chiral auxiliaries constituting CDRs, electronegativities of the atoms of achiral moieties constituting CDRs and hydrophobicities of side chains of amino acids constituting CDRs and analytes.

  12. Host-Guest Inclusion Complexes between Amlodipine Enantiomers in Biphasic Recognition Chiral Extraction System using Tartaric Acid and β-Cyclodextrin Derivatives as Positive Confirmation Using of their Enantioselective Extraction

    OpenAIRE

    AZZAM, Khaldun; ABDALLAH, Hassan; HALIM, Hairul; AHMAD, Maizatul; SHAIBAH, Hassan

    2015-01-01

    The current work reports an extended theoretical study from our previous experimental work for the enantioselective extraction of amlodipine enantiomers in a biphasic recognition chiral extraction system (BRCES) consisting of hydrophobic D-diisopropyl tartrate dissolved in organic phase (n-decanol) and hydrophilic hydroxypropyl-?-cyclodextrin (HP-?-CD) in aqueous phase (acetate buffer) which preferentially recognize the R-enantiomer and S-enantiomer, respectively. The calculations were simula...

  13. Experimental comparison of chiral metal-organic framework used as stationary phase in chromatography.

    Science.gov (United States)

    Xie, Sheng-Ming; Zhang, Mei; Fei, Zhi-Xin; Yuan, Li-Ming

    2014-10-10

    Chiral metal-organic frameworks (MOFs) are a new class of multifunctional material, which possess diverse structures and unusual properties such as high surface area, uniform and permanent cavities, as well as good chemical and thermal stability. Their chiral functionality makes them attractive as novel enantioselective adsorbents and stationary phases in separation science. In this paper, the experimental comparison of a chiral MOF [In₃O(obb)₃(HCO₂)(H₂O)] solvent used as a stationary phase was investigated in gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). The potential relationship between the structure and components of chiral MOFs with their chiral recognition ability and selectivity are presented. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Spin and chirality effects in antler-topology processes at high energy e{sup +}e{sup -} colliders

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S. Y. [Department of Physics, Chonbuk National University, 561-756, Jeonbuk (Korea, Republic of); Department of Physics and Astronomy, Pittsburgh Particle physics, Astrophysics, and Cosmology Center, University of Pittsburgh, 15260, Pittsburgh, PA (United States); Christensen, N. D. [Department of Physics, Illinois State University, 61790, Normal, IL (United States); Salmon, D.; Wang, X., E-mail: xiw77@pitt.edu [Department of Physics and Astronomy, Pittsburgh Particle physics, Astrophysics, and Cosmology Center, University of Pittsburgh, 15260, Pittsburgh, PA (United States)

    2015-10-06

    We perform a model-independent investigation of spin and chirality correlation effects in the antler-topology processes e{sup +}e{sup -}→P{sup +}P{sup -}→(ℓ{sup +}D{sup 0})(ℓ{sup -}D{sup -bar0}) at high-energy e{sup +}e{sup -} colliders with polarized beams. Generally the production process e{sup +}e{sup -}→P{sup +}P{sup -} can occur not only through the s-channel exchange of vector bosons, V{sup 0}, including the neutral Standard Model (SM) gauge bosons, γ and Z, but also through the s- and t-channel exchanges of new neutral states, S{sup 0} and T{sup 0}, and the u-channel exchange of new doubly charged states, U{sup --}. The general set of (non-chiral) three-point couplings of the new particles and leptons allowed in a renormalizable quantum field theory is considered. The general spin and chirality analysis is based on the threshold behavior of the excitation curves for P{sup +}P{sup -} pair production in e{sup +}e{sup -} collisions with longitudinal- and transverse-polarized beams, the angular distributions in the production process and also the production-decay angular correlations. In the first step, we present the observables in the helicity formalism. Subsequently, we show how a set of observables can be designed for determining the spins and chiral structures of the new particles without any model assumptions. Finally, taking into account a typical set of approximately chiral invariant scenarios, we demonstrate how the spin and chirality effects can be probed experimentally at a high-energy e{sup +}e{sup -} collider.

  15. Separation of piracetam derivatives on polysaccharide-based chiral stationary phases.

    Science.gov (United States)

    Kažoka, H; Koliškina, O; Veinberg, G; Vorona, M

    2013-03-15

    High-performance liquid chromatography was used for the enantiomeric separation of two chiral piracetam derivatives. The suitability of six commercially available polysaccharide-based chiral stationary phases (CSPs) under normal phase mode for direct enantioseparation has been investigated. The influence of the CSPs as well the nature and content of an alcoholic modifier in the mobile phase on separation and elution order was studied. It was established that CSP Lux Amylose-2 shows high chiral recognition ability towards 4-phenylsubstituted piracetam derivatives. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Chiral Selectivity in Inter-reactant Recognition and Electron Transfer of the Oxidation of Horse Heart Cytochrome c by Trioxalatocobaltate(III)

    DEFF Research Database (Denmark)

    Nazmutdinov, Renat R.; Bronshtein, Michael D.; Zinkicheva, Tamara T.

    2016-01-01

    We have studied electron transfer between cytochrome c and the chiral transition-metal complex pair Λ- and Δ-[Co(Ox)3]3− (Ox2− = oxalate) via strong ion-pair formation. Chirality was found in both ion-pair formation and electron transfer, with the Λ enantiomer the more strongly bound and faster r...... reacting. Investigations of the chirality using electron-transfer theory combined with quantum-chemical and statistical-mechanical calculations showed that chirality is solely in inter-reactant interaction and electronic overlap.......We have studied electron transfer between cytochrome c and the chiral transition-metal complex pair Λ- and Δ-[Co(Ox)3]3− (Ox2− = oxalate) via strong ion-pair formation. Chirality was found in both ion-pair formation and electron transfer, with the Λ enantiomer the more strongly bound and faster...

  17. Born term for high-energy meson-hadron collisions from QCD and chiral quark model

    International Nuclear Information System (INIS)

    Ochs, W.; Shimada, T.

    1988-01-01

    Various experimental observations reveal a sizeable hard component in the high-energy 'soft' hadronic collisions. For primary meson beams we propose a QCD Born term which describes the dissociation of the primary meson into a quark-antiquark pair in the gluon field of the target. A pointlike effective pion-quark coupling is assumed as in the chiral quark model by Manohar and Georgi. We derive the total cross sections which for pion beams, for example, are given in terms of f π -2 and some properties of the hadronic final states. In particular, we stress the importance of studying three-jet events in meson-nucleon scattering and discuss the seagull effect. (orig.)

  18. Chiral Cliffs: Investigating the Influence of Chirality on Binding Affinity.

    Science.gov (United States)

    Schneider, Nadine; Lewis, Richard A; Fechner, Nikolas; Ertl, Peter

    2018-05-11

    Chirality is understood by many as a binary concept: a molecule is either chiral or it is not. In terms of the action of a structure on polarized light, this is indeed true. When examined through the prism of molecular recognition, the answer becomes more nuanced. In this work, we investigated chiral behavior on protein-ligand binding: when does chirality make a difference in binding activity? Chirality is a property of the 3D structure, so recognition also requires an appreciation of the conformation. In many situations, the bioactive conformation is undefined. We set out to address this by defining and using several novel 2D descriptors to capture general characteristic features of the chiral center. Using machine-learning methods, we built different predictive models to estimate if a chiral pair (a set of two enantiomers) might exhibit a chiral cliff in a binding assay. A set of about 3800 chiral pairs extracted from the ChEMBL23 database was used to train and test our models. By achieving an accuracy of up to 75 %, our models provide good performance in discriminating chiral cliffs from non-cliffs. More importantly, we were able to derive some simple guidelines for when one can reasonably use a racemate and when an enantiopure compound is needed in an assay. We critically discuss our results and show detailed examples of using our guidelines. Along with this publication we provide our dataset, our novel descriptors, and the Python code to rebuild the predictive models. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synergy of Two Highly Specific Biomolecular Recognition Events

    DEFF Research Database (Denmark)

    Ejlersen, Maria; Christensen, Niels Johan; Sørensen, Kasper K

    2018-01-01

    Two highly specific biomolecular recognition events, nucleic acid duplex hybridization and DNA-peptide recognition in the minor groove, were coalesced in a miniature ensemble for the first time by covalently attaching a natural AT-hook peptide motif to nucleic acid duplexes via a 2'-amino......-LNA scaffold. A combination of molecular dynamics simulations and ultraviolet thermal denaturation studies revealed high sequence-specific affinity of the peptide-oligonucleotide conjugates (POCs) when binding to complementary DNA strands, leveraging the bioinformation encrypted in the minor groove of DNA...

  20. Optic and electro-optic investigations on SmQ, SmCA* and L phases in highly chiral compounds

    International Nuclear Information System (INIS)

    Manai, M.; Gharbi, A.; Marcerou, J.P.; Nguyen, H.T.; Rouillon, J.C.

    2005-01-01

    Chiral molecules give rise to a large variety of mesophases. Well-known examples are cholesteric or ferroelectric smectic phases where the chirality tends to favor a macroscopic twist. Furthermore, the molecular core length (l) plays an important role on the range of the mesophases and on the temperature (T NI ) for the onset of orientational order. The tendency for T NI is to increase (going over 200 - bar C for some compounds) with increasing l. We report in this paper on a selection of compounds which have been designed in order to favor an anticlinic smectic ordering together with high chirality. As a common feature, they have a long rigid core with four benzene rings and a chiral chain (usually the same) at each end. They display a locally anisotropic liquid phase referred to as ''L phase'' in a large temperature range between T NI and the low temperature SmQ or SmC A * phase. Optical rotatory power (ORP), birefringence and electro-optic studies have been performed with these compounds

  1. Spin and chirality effects in antler-topology processes at high energy e{sup +}e{sup -} colliders

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S.Y. [Chonbuk National University, Department of Physics, Jeonbuk (Korea, Republic of); University of Pittsburgh, Department of Physics and Astronomy, Pittsburgh Particle physics, Astrophysics, and Cosmology Center, Pittsburgh, PA (United States); Christensen, N.D. [Illinois State University, Department of Physics, Normal, IL (United States); Salmon, D.; Wang, X. [University of Pittsburgh, Department of Physics and Astronomy, Pittsburgh Particle physics, Astrophysics, and Cosmology Center, Pittsburgh, PA (United States)

    2015-10-15

    We perform a model-independent investigation of spin and chirality correlation effects in the antler-topology processes e{sup +}e{sup -} → P{sup +}P{sup -} → (l{sup +}D{sup 0})(l{sup +} anti D{sup 0}) at highenergy e{sup +}e{sup -} colliders with polarized beams. Generally the production process e{sup +}e{sup -} → P{sup +}P{sup -} can occur not only through the s-channel exchange of vector bosons, V{sup 0}, including the neutral Standard Model (SM) gauge bosons, γ and Z, but also through the s- and t-channel exchanges of new neutral states, S{sup 0} and T{sup 0}, and the u-channel exchange of new doubly charged states, U{sup --}. The general set of (nonchiral) three-point couplings of the new particles and leptons allowed in a renormalizable quantum field theory is considered. The general spin and chirality analysis is based on the threshold behavior of the excitation curves for P{sup +}P{sup -} pair production in e{sup +}e{sup -} collisions with longitudinal- and transverse-polarized beams, the angular distributions in the production process and also the production-decay angular correlations. In the first step, we present the observables in the helicity formalism. Subsequently, we show how a set of observables can be designed for determining the spins and chiral structures of the new particles without any model assumptions. Finally, taking into account a typical set of approximately chiral invariant scenarios, we demonstrate how the spin and chirality effects can be probed experimentally at a high-energy e{sup +}e{sup -} collider. (orig.)

  2. Applications of chiral symmetry

    International Nuclear Information System (INIS)

    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 χ implies that the ρ and a 1 vector mesons are degenerate in mass. In a gauged linear sigma model the ρ mass increases with temperature, m ρ (T χ ) > m ρ (0). The author conjectures that at T χ the thermal ρ - a 1 , peak is relatively high, at about ∼1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The ω meson also increases in mass, nearly degenerate with the ρ, but its width grows dramatically with temperature, increasing to at least ∼100 MeV by T χ . 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 quenchedclose 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

  3. Recognition

    DEFF Research Database (Denmark)

    Gimmler, Antje

    2017-01-01

    In this article, I shall examine the cognitive, heuristic and theoretical functions of the concept of recognition. To evaluate both the explanatory power and the limitations of a sociological concept, the theory construction must be analysed and its actual productivity for sociological theory mus...

  4. High-performance liquid chromatographic enantioseparation of unusual isoxazoline-fused 2-aminocyclopentanecarboxylic acids on macrocyclic glycopeptide-based chiral stationary phases.

    Science.gov (United States)

    Sipos, László; Ilisz, István; Nonn, Melinda; Fülöp, Ferenc; Pataj, Zoltán; Armstrong, Daniel W; Péter, Antal

    2012-04-06

    The enantiomers of four unusual isoxazoline-fused 2-aminocyclopentanecarboxylic acids were directly separated on chiral stationary phases containing macrocyclic glycopeptide antibiotics teicoplanin (Astec Chirobiotic T and T2), teicoplanin aglycone (Chirobiotic TAG), vancomycin (Chirobiotic V) and vancomycin aglycone (Chirobiotic VAG) as chiral selectors. The effects of the mobile phase composition, the structure of the analytes and temperature on the separations were investigated. Experiments were performed at constant mobile phase compositions in the temperature range 5-45 °C to study the effects of temperature, and thermodynamic parameters were calculated from plots of lnk or lnα versus 1/T. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes. It was found that the enantiomeric separations were in most cases enthalpy-driven. The sequence of elution of the enantiomers was determined in all cases. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Enantioseparation of pheniramine enantiomers by high-speed countercurrent chromatography using β-cyclodextrin derivatives as a chiral selector.

    Science.gov (United States)

    Xu, Weifeng; Wang, Shichuan; Xie, Xiaojuan; Zhang, Panliang; Tang, Kewen

    2017-10-01

    The enantioselective separation of pheniramine was studied by a high-speed countercurrent chromatography method using β-cyclodextrin derivatives as a chiral selector. Several key variables, for instance, type of organic solvent and chiral selector, concentration of chiral selector, pH value of aqueous phase, and temperature on the enantioselectivity, were investigated systematically by liquid-liquid extraction experiments. Combining the results of extraction experiments and high-speed countercurrent chromatography, the most suitable conditions for separation of pheniramine enantiomers were obtained with the two-phase system that consisted of isobutyl acetate/aqueous phase, containing 0.02 mol/L carboxymethyl-β-cyclodextrin, pH 8.50 at 278.15 K. Under the optimal conditions, pheniramine enantiomer was successfully resolved after four cycles of high-speed countercurrent chromatography. By using high-performance liquid chromatography to analyze the fractions, the purities of both (+)-pheniramine and (-)-pheniramine were over 99% and the recovery of this method was up to 85-90%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Chiral superconductors.

    Science.gov (United States)

    Kallin, Catherine; Berlinsky, John

    2016-05-01

    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 chiral triplet p-wave superconductor, and UPt3, which has two low-temperature superconducting phases (in zero magnetic field), the lower of which is believed to be chiral triplet f-wave. Other systems that may exhibit chiral superconductivity are also discussed. Key signatures of chiral superconductivity are surface currents and chiral Majorana modes, Majorana states in vortex cores, and the possibility of half-flux quantum vortices in the case of triplet pairing. Experimental evidence for chiral superconductivity from μSR, NMR, strain, polar Kerr effect and Josephson tunneling experiments are discussed.

  7. Chiral Responsive Liquid Quantum Dots.

    Science.gov (United States)

    Zhang, Jin; Ma, Junkai; Shi, Fangdan; Tian, Demei; Li, Haibing

    2017-08-01

    How to convert the weak chiral-interaction into the macroscopic properties of materials remains a huge challenge. Here, this study develops highly fluorescent, selectively chiral-responsive liquid quantum dots (liquid QDs) based on the hydrophobic interaction between the chiral chains and the oleic acid-stabilized QDs, which have been designated as (S)-1810-QDs. The fluorescence spectrum and liquidity of thermal control demonstrate the fluorescence properties and the fluidic behavior of (S)-1810-QDs in the solvent-free state. Especially, (S)-1810-QDs exhibit a highly chiral-selective response toward (1R, 2S)-2-amino-1,2-diphenyl ethanol. It is anticipated that this study will facilitate the construction of smart chiral fluidic sensors. More importantly, (S)-1810-QDs can become an attractive material for chiral separation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Theoretical study of high-Q Fano resonance and extrinsic chirality in an ultrathin Babinet-inverted metasurface

    Science.gov (United States)

    Wang, Feng; Wang, Zhengping; Shi, Jinhui

    2014-10-01

    A high-Q Fano resonance and giant extrinsic chirality have been demonstrated in an ultrathin Babinet-inverted metasurface composed of asymmetrical split ring apertures (ASRAs) perforated through a metal plate based on the full-wave simulations. The performance of the Fano resonance at normal incidence strongly depends on the asymmetry of the ASRA. The quality factor is larger than 1000 and the local field enhancement is an order of 104. For oblique incidence, giant extrinsic chirality can be achieved in the Babinet-inverted metasurface. It reveals a cross-polarization transmission band with a ripple-free peak and also a spectrum split for large angles of incidence. The electromagnetic response of the metasurface can be easily tuned via angles of incidence and asymmetry. The proposed ASRA metasurface is of importance to develop many metamaterial-based devices, such as filters and circular polarizers.

  9. Searching for Models Exhibiting High Circularly Polarized Luminescence: the Electroactive Inherently Chiral Oligothiophenes.

    Science.gov (United States)

    Benincori, Tiziana; Appoloni, Giulio; Mussini, Patrizia Romana; Arnaboldi, Serena; Cirilli, Roberto; Quartapelle Procopio, Elsa; Panigati, Monica; Abbate, Sergio; Mazzeo, Giuseppe; Longhi, Giovanna

    2018-05-02

    Two new inherently chiral oligothiophenes characterized by the atropisomeric 3,3'-bithianaphtene scaffold functionalized with fused ring bithiophene derivatives, namely 4H-cyclopenta [2,1-b3:4b']dithiophene (CPDT) and dithieno[3,3-b:2',3'-d]pyrrole (DTP), were synthesized. The racemates were fully characterized and resolved into antipodes by enantioselective HPLC. The enantiomers were analyzed through different chiroptical techniques: electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were employed to attribute the absolute configuration (AC). Comparison of experimental and calculated VCD spectra confirmed the DFT calculated conformational characteristics. The compound functionalized with two CPDT units was oxidized with FeCl3 and ECD and CPL of the resulting material were measured. Circularly Polarized Luminescence (CPL) was measured in order to verify if inherently chiral oligothiophenes could be promising systems for chiral photonics applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Functional chiral hydrogen-bonded assemblies

    NARCIS (Netherlands)

    Mateos timoneda, Miguel

    2005-01-01

    In this thesis different aspects of functional hydrogen-bonded (double and tetrarosette) assemblies are described. The functions were inspired by naturally occurring mechanisms such as molecular recognition, supramolecular chirality and its origin, and biostrategies for the correct folding of

  11. Intrinsic Chirality and Prochirality at Air/R-(+)- and S-(-)-Limonene Interfaces: Spectral Signatures with Interference Chiral Sum-Frequency Generation Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Li; Zhang, Yun; Wei, Zhehao; Wang, Hongfei

    2014-06-04

    We report in this work detailed measurements on the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050cm-1) of the air/liquid interfaces of R-limonene and S-limonene, using the recently developed high-resolution broadband sum-frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The achiral SFG spectra of R-limonene and S-limonene, as well as the equal amount (50/50) racemic mixture show that the enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit spectral signature from chiral response of the Cα-H stretching mode, and spectral signature from prochiral response of the CH2 asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-limonene to S-limonene, and disappears for the 50/50 racemic mixture. While the prochiral spectral feature of the CH2 asymmetric stretching mode is the same for R-limonene and S-limonene, and also surprisingly remains the same for the 50/50 racemic mixture. These results provided detail information in understanding the structure and chirality of molecular interfaces, and demonstrated the sensitivity and potential of SFG-VS as unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface.

  12. New chiral and restricted-access materials containing glycopeptides as selectors for the high-performance liquid chromatographic determination of chiral drugs in biological matrices.

    Science.gov (United States)

    Gasparrini, Francesco; Cancelliere, Giovanna; Ciogli, Alessia; D'Acquarica, Ilaria; Misiti, Domenico; Villani, Claudio

    2008-05-16

    Two new chiral and restricted-access materials containing glycopeptide antibiotics as chiral selectors (chiro-Glyco-RAM) were designed, suitable for the direct HPLC injection of biological fluids containing chiral drugs without any sample pre-treatment or pre-columns coupling. The external surface of the porous silica support was covered with a bio-compatible hydrophilic polymeric network (polyvinyl alcohol, PVA) while the chiral phase based on either teicoplanin (TE) or teicoplanin aglycone (TAG) was exclusively confined to the internal region. The chiro-Glyco-RAM supports were synthesized by the following steps: (a) introduction of 3-aminopropyl groups on 100 A pore size silica gel; (b) activation of the aminopropylated silica with 1,6-diisocyanatohexane; (c) functionalization of the external region of the porous silica with PVA; (d) covalent linking of TE/TAG to the internal surface. The average pore diameter of the chiro-Glyco-RAM supports, calculated by inverse size-exclusion chromatography (ISEC), was about 80 A and able to exclude macromolecules heavier than about 20,000 Da (such as the most abundant serum proteins) from the pores. The recovery of bovine serum albumin (BSA) was almost quantitative. HPLC analyses of model chiral drugs were performed using hydro-organic mobile phases consisting of an organic solvent (acetonitrile or methanol) and aqueous solutions of ammonium acetate (0.020 M) or ammonium formate (0.0025-0.0050 M).

  13. Fases estacionárias quirais para cromatografia líquida de alta eficiência Chiral stationary phases for high-performance liquid chromatography

    OpenAIRE

    Tiago de Campos Lourenço; Neila Maria Cassiano; Quezia B. Cass

    2010-01-01

    The development of Chiral Stationary Phases (CSPs) for high performance liquid chromatography has been studied by various researches around the world, especially, since 1980. This simple interest has been transformed into a tool of great technological value for the industrial community and scholars in general providing the existence of several CSPs, which act through different mechanisms of chiral discrimination. This paper describes the main types of CSPs that are used for the resolution of ...

  14. Analytical and semipreparative chiral separation of cis-itraconazole on cellulose stationary phases by high-performance liquid chromatography.

    Science.gov (United States)

    Kurka, Ondřej; Kučera, Lukáš; Bednář, Petr

    2016-07-01

    cis-Itraconazole is a chiral antifungal drug administered as a racemate. The knowledge of properties of individual cis-itraconazole stereoisomers is vital information for medicine and biosciences as different stereoisomers of cis-itraconazole may possess different affinity to certain biological pathways in the human body. For this purpose, either chiral synthesis of enantiomers or chiral separation of racemate can be used. This paper presents a two-step high-performance liquid chromatography approach for the semipreparative isolation of four stereoisomers (two enantiomeric pairs) of itraconazole using polysaccharide stationary phases and volatile organic mobile phases without additives in isocratic mode. The approach used involves the separation of the racemate into three fractions (i.e. two pure stereoisomers and one mixed fraction containing the remaining two stereoisomers) in the first run and consequent separation of the collected mixed fraction in the second one. For this purpose, combination of cellulose tris-(4-methylbenzoate) and cellulose tris-(3,5-dimehylphenylcarbamate) columns with complementary selectivity for cis-itraconazole provided full separation of all four stereoisomers (with purity of each isomer > 97%). The stereoisomers were collected, their optical rotation determined and their identity confirmed based on the results of a previously published study. Pure separated stereoisomers are subjected to further biological studies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A High-Resolution Magic Angle Spinning NMR Study of the Enantiodiscrimination of 3,4-Methylenedioxymethamphetamine (MDMA by an Immobilized Polysaccharide-Based Chiral Phase.

    Directory of Open Access Journals (Sweden)

    Juliana C Barreiro

    Full Text Available This paper reports the investigation of the chiral interaction between 3,4-methylenedioxy-methamphetamine (MDMA enantiomers and an immobilized polysaccharide-based chiral phase. For that, suspended-state high-resolution magic angle spinning nuclear magnetic resonance spectroscopy (1H HR-MAS NMR was used. 1H HR-MAS longitudinal relaxation time and Saturation Transfer Difference (STD NMR titration experiments were carried out yielding information at the molecular level of the transient diastereoisomeric complexes of MDMA enantiomers and the chiral stationary phase. The interaction of the enantiomers takes place through the aromatic moiety of MDMA and the aromatic group of the chiral selector by π-π stacking for both enantiomers; however, a stronger interaction was observed for the (R-enantiomer, which is the second one to elute at the chromatographic conditions.

  16. 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.

  17. Synthesis of a series of soluble main-chain chiral nonracemic poly(alkyl-aryl ketone

    Directory of Open Access Journals (Sweden)

    2008-06-01

    Full Text Available A series of main-chain chiral polyketones have been synthesized through condensation polymerization of a dihalide and a diketone with optically pure binaphthyl moiety as linkage in the polymer backbone. The solubility of the polymers can be easily enhanced by substituents at the alpha position next to the carbonyl groups. Reducing the steric hindrance of the substituents in the monomers increases the reactivity of the polymerization. The chiral polymers exhibit large optical rotations. Circular Dichroism (CD spectra of the polymers are similar to those of the corresponding monomers. The novel synthetic strategy may have great impact on future development of palladium catalyzed condensation polymerizations. The highly soluble chiral polymers synthesized allow for preparation of materials in the form of thin films and have potentials applications in various areas such as chiral separation and recognition.

  18. The Optical Resolution of Chiral Tetrahedrone-type Clusters Contai- ning SCoFeM (M=Mo or W) Using High Performance Liquid Chromatography Chiral Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amylose tris (phenylcarbamate) chiral stationary phase (ATPC-CSP) was prepared and used for optical resolution of clusters 1 and 2. n-Hexane/2-propanol ( 99/1; v/v) were found to be the most suitable mobile phase on ATPC-CSP.

  19. Chirality in adsorption on solid surfaces.

    Science.gov (United States)

    Zaera, Francisco

    2017-12-07

    In the present review we survey the main advances made in recent years on the understanding of chemical chirality at solid surfaces. Chirality is an important topic, made particularly relevant by the homochiral nature of the biochemistry of life on Earth, and many chiral chemical reactions involve solid surfaces. Here we start our discussion with a description of surface chirality and of the different ways that chirality can be bestowed on solid surfaces. We then expand on the studies carried out to date to understand the adsorption of chiral compounds at a molecular level. We summarize the work published on the adsorption of pure enantiomers, of enantiomeric mixtures, and of prochiral molecules on chiral and achiral model surfaces, especially on well-defined metal single crystals but also on other flat substrates such as highly ordered pyrolytic graphite. Several phenomena are identified, including surface reconstruction and chiral imprinting upon adsorption of chiral agents, and the enhancement or suppression of enantioselectivity seen in some cases upon adsorption of enantiomixtures of chiral compounds. The possibility of enhancing the enantiopurity of adsorbed layers upon the addition of chiral seeds and the so-called "sergeants and soldiers" phenomenon are presented. Examples are provided where the chiral behavior has been associated with either thermodynamic or kinetic driving forces. Two main approaches to the creation of enantioselective surface sites are discussed, namely, via the formation of supramolecular chiral ensembles made out of small chiral adsorbates, and by adsorption of more complex chiral molecules capable of providing suitable chiral environments for reactants by themselves, via the formation of individual adsorbate:modifier adducts on the surface. Finally, a discussion is offered on the additional effects generated by the presence of the liquid phase often required in practical applications such as enantioselective crystallization, chiral

  20. 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

    Molecular-level insights into chiral adsorption phenomena are highly relevant within the fields of asymmetric heterogeneous catalysis or chiral separation and may contribute to understand the origins of homochirality in nature. Here, we investigate chiral induction by the "sergeants and soldiers......" 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...... molecules down to 3%. The microscopic mechanism for the observed chiral induction is suggested to involve nucleation of the intrinsically chiral seeds, allowing for effective transfer and amplification of chirality to large numbers of soldier target molecules....

  1. Localised polymer networks in chiral nematic liquid crystals for high speed photonic switching

    International Nuclear Information System (INIS)

    Tartan, Chloe C.; Salter, Patrick S.; Booth, Martin J.; Morris, Stephen M.; Elston, Steve J.

    2016-01-01

    Self-assembled periodic structures based upon chiral liquid crystalline materials have significant potential in the field of photonics ranging from fast-switching optoelectronic devices to low-threshold lasers. The flexoelectro-optic effect, which is observed in chiral nematic liquid crystals (LCs) when an electric field is applied perpendicular to the helical axis, has significant potential as it exhibits analogue switching in 10–100 μs. However, the major technological barrier that prohibits the commercial realisation of this electro-optic effect is the requirement of a uniform, in-plane alignment of the helix axis between glass substrates. Here, it is shown that periodic polymer structures engineered in the nematic phase of a chiral nematic LC device using direct laser writing can result in the spontaneous formation of the necessary uniform lying helix (ULH) state. Specifically, two-photon polymerization is used in conjunction with a spatial light modulator so as to correct for aberrations introduced by the bounding glass substrates enabling the polymer structures to be fabricated directly into the device. The ULH state appears to be stable in the absence of an externally applied electric field, and the optimum contrast between the bright and dark states is obtained using polymer structures that have periodicities of the order of the device thickness.

  2. Localised polymer networks in chiral nematic liquid crystals for high speed photonic switching

    Energy Technology Data Exchange (ETDEWEB)

    Tartan, Chloe C., E-mail: chloe.tartan@eng.ox.ac.uk, E-mail: steve.elston@eng.ox.ac.uk; Salter, Patrick S.; Booth, Martin J.; Morris, Stephen M.; Elston, Steve J., E-mail: chloe.tartan@eng.ox.ac.uk, E-mail: steve.elston@eng.ox.ac.uk [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom)

    2016-05-14

    Self-assembled periodic structures based upon chiral liquid crystalline materials have significant potential in the field of photonics ranging from fast-switching optoelectronic devices to low-threshold lasers. The flexoelectro-optic effect, which is observed in chiral nematic liquid crystals (LCs) when an electric field is applied perpendicular to the helical axis, has significant potential as it exhibits analogue switching in 10–100 μs. However, the major technological barrier that prohibits the commercial realisation of this electro-optic effect is the requirement of a uniform, in-plane alignment of the helix axis between glass substrates. Here, it is shown that periodic polymer structures engineered in the nematic phase of a chiral nematic LC device using direct laser writing can result in the spontaneous formation of the necessary uniform lying helix (ULH) state. Specifically, two-photon polymerization is used in conjunction with a spatial light modulator so as to correct for aberrations introduced by the bounding glass substrates enabling the polymer structures to be fabricated directly into the device. The ULH state appears to be stable in the absence of an externally applied electric field, and the optimum contrast between the bright and dark states is obtained using polymer structures that have periodicities of the order of the device thickness.

  3. Localised polymer networks in chiral nematic liquid crystals for high speed photonic switching

    Science.gov (United States)

    Tartan, Chloe C.; Salter, Patrick S.; Booth, Martin J.; Morris, Stephen M.; Elston, Steve J.

    2016-05-01

    Self-assembled periodic structures based upon chiral liquid crystalline materials have significant potential in the field of photonics ranging from fast-switching optoelectronic devices to low-threshold lasers. The flexoelectro-optic effect, which is observed in chiral nematic liquid crystals (LCs) when an electric field is applied perpendicular to the helical axis, has significant potential as it exhibits analogue switching in 10-100 μs. However, the major technological barrier that prohibits the commercial realisation of this electro-optic effect is the requirement of a uniform, in-plane alignment of the helix axis between glass substrates. Here, it is shown that periodic polymer structures engineered in the nematic phase of a chiral nematic LC device using direct laser writing can result in the spontaneous formation of the necessary uniform lying helix (ULH) state. Specifically, two-photon polymerization is used in conjunction with a spatial light modulator so as to correct for aberrations introduced by the bounding glass substrates enabling the polymer structures to be fabricated directly into the device. The ULH state appears to be stable in the absence of an externally applied electric field, and the optimum contrast between the bright and dark states is obtained using polymer structures that have periodicities of the order of the device thickness.

  4. Vectorial control of nonlinear emission via chiral butterfly nanoantennas: generation of pure high order nonlinear vortex beams.

    Science.gov (United States)

    Lesina, Antonino Cala'; Berini, Pierre; Ramunno, Lora

    2017-02-06

    We report on a chiral gap-nanostructure, which we term a "butterfly nanoantenna," that offers full vectorial control over nonlinear emission. The field enhancement in its gap occurs for only one circular polarization but for every incident linear polarization. As the polarization, phase and amplitude of the linear field in the gap are highly controlled, the linear field can drive nonlinear emitters within the gap, which behave as an idealized Huygens source. A general framework is thereby proposed wherein the butterfly nanoantennas can be arranged in a metasurface, and the nonlinear Huygens sources exploited to produce a highly structured far-field optical beam. Nonlinearity allows us to shape the light at shorter wavelengths, not accessible by linear plasmonics, and resulting in high purity beams. The chirality of the butterfly allows us to create orbital angular momentum states using a linearly polarized excitation. A third harmonic Laguerre-Gauss beam carrying an optical orbital angular momentum of 41 is demonstrated as an example, through large-scale simulations on a high-performance computing platform of the full plasmonic metasurface with an area large enough to contain up to 3600 nanoantennas.

  5. Nitrile ylides: diastereoselective cycloadditions using chiral oxazolidinones without Lewis acid.

    Science.gov (United States)

    Sibi, Mukund P; Soeta, Takahiro; Jasperse, Craig P

    2009-12-03

    Lewis acid complexation is generally required for chiral-auxiliary-controlled stereoselectivity, and chiral Lewis acid catalysis is frequently optimal for introducing asymmetry. In this work, we show that nitrile ylide cycloadditions to electron-poor acceptors attached to chiral auxiliaries proceed in high yield and stereoselectivity in the absence of Lewis acids. In contrast, chiral Lewis acids are inferior in these cycloadditions.

  6. Chiral ionic liquids in chromatographic and electrophoretic separations.

    Science.gov (United States)

    Kapnissi-Christodoulou, Constantina P; Stavrou, Ioannis J; Mavroudi, Maria C

    2014-10-10

    This report provides an overview of the application of chiral ionic liquids (CILs) in separation technology, and particularly in capillary electrophoresis and both gas and liquid chromatography. There is a large number of CILs that have been synthesized and designed as chiral agents. However, only a few have successfully been applied in separation technology. Even though this application of CILs is still in its early stages, the scientific interest is increasing dramatically. This article is focused on the use of CILs as chiral selectors, background electrolyte additives, chiral ligands and chiral stationary phases in electrophoretic and chromatographic techniques. Different examples of CILs, which contain either a chiral cation, a chiral anion or both, are presented in this review article, and their major advantages along with their potential applications in chiral electrophoretic and chromatographic recognition are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Asymmetric chiral colour

    International Nuclear Information System (INIS)

    Cuypers, F.

    1990-01-01

    Chiral colour is considered in a general framework where the coupling constants associated with each SU(3) component are allowed to be different. To reproduce QCD at low energy, gluons and axigluons cannot then be maximally mixed. Present data form e + e - colliders contrains the axigluon mass to values between 50 GeV and 375 GeV whilst the mixing angle is bounded by 13deg and 45deg. The lower limit of the axigluon mass is a definite bound at 90% C.L., whereas the upper limit only applies if chiral colour is to explain the anomalously high rates of hadron production at TRISTAN. (orig.)

  8. Chirality invariance and 'chiral' fields

    International Nuclear Information System (INIS)

    Ziino, G.

    1978-01-01

    The new field model derived in the present paper actually gives a definite answer to three fundamental questions concerning elementary-particle physics: 1) The phenomenological dualism between parity and chirality invariance: it would be only an apparent display of a general 'duality' principle underlying the intrinsic nature itself of (spin 1/2) fermions and expressed by the anticommutativity property between scalar and pseudoscalar charges. 2) The real physical meaning of V - A current structure: it would exclusively be connected to the one (just pointed out) of chiral fields themselves. 3) The unjustified apparent oddness shown by Nature in weak interactions, for the fact of picking out only one of the two (left- and right-handed) fermion 'chiral' projections: the key to such a 'mystery' would just be provided by the consequences of the dual and partial character of the two fermion-antifermion field bases. (Auth.)

  9. Stereoelectronic model to explain the resolution of enantiomeric ibuprofen amides on the Pirkle chiral stationary phase.

    Science.gov (United States)

    Nicoll-Griffith, D A

    1987-07-31

    A chiral recognition model is proposed which incorporates the electronic and steric interactions between amide derivatives of ibuprofen and the (R)-N-(3,5-dinitrobenzoyl)phenylglycine-derived Pirkle chiral stationary phase during high-performance liquid chromatography. Based on this rationale, amide derivatives of ibuprofen were prepared using 4-chloroaniline, 4-bromoaniline, aniline, 4-methoxyaniline and 1-aminonaphthylene to improve the enantiomer separation over previously reported results with this column. The amides prepared gave separation values of 1.16, 1.16, 1.19, 1.21 and 1.23, respectively. These high separation values are consistent with the proposed model.

  10. Direct enantioseparation of nitrogen-heterocyclic pesticides on cellulose-based chiral column by high-performance liquid chromatography.

    Science.gov (United States)

    Chai, Tingting; Yang, Wenwen; Qiu, Jing; Hou, Shicong

    2015-01-01

    The enantiomeric separation of eight pesticides including bitertanol (), diclobutrazol (), fenbuconazole (), triticonazole (), imazalil (), triapenthenol (), ancymidol (), and carfentrazone-ethyl () was achieved, using normal-phase high-performance liquid chromatography on two cellulosed-based chiral columns. The effects of isopropanol composition from 2% to 30% in the mobile phase and column temperature from 5 to 40 °C were investigated. Satisfactory resolutions were obtained for bitertanol (), triticonazole (), imazalil () with the (+)-enantiomer eluted first and fenbuconazole () with the (-)-enantiomer eluted first on Lux Cellulose-2 and Lux Cellulose-3. (+)-Enantiomers of diclobutrazol () and triapenthenol () were first eluted on Lux Cellulose-2. (-)-Carfentrazone-ethyl () were eluted first on Lux Cellulose-2 and Lux Cellulose-3 with incomplete separation. Reversed elution orders were obtained for ancymidol (7). (+)-Ancymidol was first eluted on Lux Cellulose-2 while on Lux Cellulose-3 (-)-ancymidol was first eluted. The results of the elution order at different column temperatures suggested that column temperature did not affect the optical signals of the enantiomers. These results will be helpful to prepare and analyze individual enantiomers of chiral pesticides. © 2014 Wiley Periodicals, Inc.

  11. High Pressure Diels Alder Reactions of 1-Vinyl-2,2,6-trimethylcyclohexene Catalyzed by Chiral Lewis Acids; An Enantioselective Route to a Drimane Sesquiterpene Precursor.

    NARCIS (Netherlands)

    Knol, Joop; Meetsma, Auke; Feringa, Bernard

    1995-01-01

    The Diels Alder reaction of 1-vinyl-2,2,6-trimethylcyclohexene and 3-((E)-3-(methoxycarbonyl)propenoyl)-1,3-oxazolidin-2-one under high pressure, catalyzed by a chiral bis-imine copper(II) complex, yields a drimane sesquiterpene precursor in a highly regio- and diastereoselective manner with

  12. Recent Progress in Asymmetric Catalysis and Chromatographic Separation by Chiral Metal–Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Suchandra Bhattacharjee

    2018-03-01

    Full Text Available Metal–organic frameworks (MOFs, as a new class of porous solid materials, have emerged and their study has established itself very quickly into a productive research field. This short review recaps the recent advancement of chiral MOFs. Here, we present simple, well-ordered instances to classify the mode of synthesis of chiral MOFs, and later demonstrate the potential applications of chiral MOFs in heterogeneous asymmetric catalysis and enantioselective separation. The asymmetric catalysis sections are subdivided based on the types of reactions that have been successfully carried out recently by chiral MOFs. In the part on enantioselective separation, we present the potentiality of chiral MOFs as a stationary phase for high-performance liquid chromatography (HPLC and high-resolution gas chromatography (GC by considering fruitful examples from current research work. We anticipate that this review will provide interest to researchers to design new homochiral MOFs with even greater complexity and effort to execute their potential functions in several fields, such as asymmetric catalysis, enantiomer separation, and chiral recognition.

  13. Chiral supramolecular organization from a sheet-like achiral gel: a study of chiral photoinduction.

    Science.gov (United States)

    Royes, Jorge; Polo, Víctor; Uriel, Santiago; Oriol, Luis; Piñol, Milagros; Tejedor, Rosa M

    2017-05-31

    Chiral photoinduction in a photoresponsive gel based on an achiral 2D architecture with high geometric anisotropy and low roughness has been investigated. Circularly polarized light (CPL) was used as a chiral source and an azobenzene chromophore was employed as a chiral trigger. The chiral photoinduction was studied by evaluating the preferential excitation of enantiomeric conformers of the azobenzene units. Crystallographic data and density functional theory (DFT) calculations show how chirality is transferred to the achiral azomaterials as a result of the combination of chiral photochemistry and supramolecular interactions. This procedure could be applied to predict and estimate chirality transfer from a chiral physical source to a supramolecular organization using different light-responsive units.

  14. Chirality effect in disordered graphene ribbon junctions

    International Nuclear Information System (INIS)

    Long Wen

    2012-01-01

    We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon. (paper)

  15. Chiral Amine Synthesis Using ω-Transaminases: An Amine Donor that Displaces Equilibria and Enables High-Throughput Screening**

    Science.gov (United States)

    Green, Anthony P; Turner, Nicholas J; O'Reilly, Elaine

    2014-01-01

    The widespread application of ω-transaminases as biocatalysts for chiral amine synthesis has been hampered by fundamental challenges, including unfavorable equilibrium positions and product inhibition. Herein, an efficient process that allows reactions to proceed in high conversion in the absence of by-product removal using only one equivalent of a diamine donor (ortho-xylylenediamine) is reported. This operationally simple method is compatible with the most widely used (R)- and (S)-selective ω-TAs and is particularly suitable for the conversion of substrates with unfavorable equilibrium positions (e.g., 1-indanone). Significantly, spontaneous polymerization of the isoindole by-product generates colored derivatives, providing a high-throughput screening platform to identify desired ω-TA activity. PMID:25138082

  16. Structure recognition from high resolution images of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Perciano, Talita; Krishnan, Harinarayan; Loring, Burlen; Bale, Hrishikesh; Parkinson, Dilworth; Sethian, James

    2015-01-05

    Fibers provide exceptional strength-to-weight ratio capabilities when woven into ceramic composites, transforming them into materials with exceptional resistance to high temperature, and high strength combined with improved fracture toughness. Microcracks are inevitable when the material is under strain, which can be imaged using synchrotron X-ray computed micro-tomography (mu-CT) for assessment of material mechanical toughness variation. An important part of this analysis is to recognize fibrillar features. This paper presents algorithms for detecting and quantifying composite cracks and fiber breaks from high-resolution image stacks. First, we propose recognition algorithms to identify the different structures of the composite, including matrix cracks and fibers breaks. Second, we introduce our package F3D for fast filtering of large 3D imagery, implemented in OpenCL to take advantage of graphic cards. Results show that our algorithms automatically identify micro-damage and that the GPU-based implementation introduced here takes minutes, being 17x faster than similar tools on a typical image file.

  17. High-quality two-nucleon potentials up to fifth order of the chiral expansion

    Science.gov (United States)

    Entem, D. R.; Machleidt, R.; Nosyk, Y.

    2017-08-01

    We present NN potentials through five orders of chiral effective field theory ranging from leading order (LO) to next-to-next-to-next-to-next-to-leading order (N4LO ). The construction may be perceived as consistent in the sense that the same power counting scheme as well as the same cutoff procedures are applied in all orders. Moreover, the long-range parts of these potentials are fixed by the very accurate π N low-energy constants (LECs) as determined in the Roy-Steiner equations analysis by Hoferichter, Ruiz de Elvira, and coworkers. In fact, the uncertainties of these LECs are so small that a variation within the errors leads to effects that are essentially negligible, reducing the error budget of predictions considerably. The NN potentials are fit to the world NN data below the pion-production threshold of the year 2016. The potential of the highest order (N4LO ) reproduces the world NN data with the outstanding χ2/datum of 1.15, which is the highest precision ever accomplished for any chiral NN potential to date. The NN potentials presented may serve as a solid basis for systematic ab initio calculations of nuclear structure and reactions that allow for a comprehensive error analysis. In particular, the consistent order by order development of the potentials will make possible a reliable determination of the truncation error at each order. Our family of potentials is nonlocal and, generally, of soft character. This feature is reflected in the fact that the predictions for the triton binding energy (from two-body forces only) converges to about 8.1 MeV at the highest orders. This leaves room for three-nucleon-force contributions of moderate size.

  18. Consistent, high-quality two-nucleon potentials up to fifth order of the chiral expansion

    Science.gov (United States)

    Machleidt, R.

    2018-02-01

    We present N N potentials through five orders of chiral effective field theory ranging from leading order (LO) to next-to-next-to-next-to-next-to-leading order (N4LO). The construction may be perceived as consistent in the sense that the same power counting scheme as well as the same cutoff procedures are applied in all orders. Moreover, the long-range parts of these potentials are fixed by the very accurate πN low-energy constants (LECs) as determined in the Roy-Steiner equations analysis by Hoferichter, Ruiz de Elvira and coworkers. In fact, the uncertainties of these LECs are so small that a variation within the errors leads to effects that are essentially negligible, reducing the error budget of predictions considerably. The N N potentials are fit to the world N N data below pion-production threshold of the year of 2016. The potential of the highest order (N4LO) reproduces the world N N data with the outstanding χ 2/datum of 1.15, which is the highest precision ever accomplished for any chiral N N potential to date. The N N potentials presented may serve as a solid basis for systematic ab initio calculations of nuclear structure and reactions that allow for a comprehensive error analysis. In particular, the consistent order by order development of the potentials will make possible a reliable determination of the truncation error at each order. Our family of potentials is non-local and, generally, of soft character. This feature is reflected in the fact that the predictions for the triton binding energy (from two-body forces only) converges to about 8.1 MeV at the highest orders. This leaves room for three-nucleon-force contributions of moderate size.

  19. Chiral symmetry restoration versus deconfinement in heavy-ion collisions at high baryon density

    Science.gov (United States)

    Bratkovskaya, E. L.; Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Moreau, P.

    2017-07-01

    The effect of the chiral symmetry restoration (CSR) on observables from heavy-ion collisions is studied in the energy range \\sqrt{{s}NN}=3-20 {GeV} within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear σ - ω model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations. For the pion-nucleon Σ-term we adopt Σ π ≈ 45 MeV which corresponds to some ‘world average’. Our systematic studies show that chiral symmetry restoration plays a crucial role in the description of heavy-ion collisions at \\sqrt{{s}NN}=3-20 {GeV}, realizing an increase of the hadronic particle production in the strangeness sector with respect to the non-strange one. We identify particle abundances and rapidity spectra to be suitable probes in order to extract information about CSR, while transverse mass spectra are less sensitive. Our results provide a microscopic explanation for the “horn” structure in the excitation function of the K +/π + ratio: the CSR in the hadronic phase produces the steep increase of this particle ratio up to \\sqrt{{s}NN}≈ 7 {GeV}, while the drop at higher energies is associated to the appearance of a deconfined partonic medium.

  20. Vector mesons and chiral symmetry

    International Nuclear Information System (INIS)

    Ecker, G.

    1989-01-01

    The ambiguities in the off-shell behaviour of spin-1 exchange can be resolved to O(p 4 ) in the chiral low-energy expansion if the asymptotic behaviour of QCD is properly incorporated. As a consequence, the chiral version of vector (and axial-vector) meson dominance is model independent. Additional high-energy constraints motivated by QCD determine the V,A resonance couplings uniquely. In particular, QCD in its effective chiral realization sucessfully predicts Γ(ρ→2π). 10 refs. (Author)

  1. Examination of the Potential for Adaptive Chirality of the Nitrogen Chiral Center in Aza-Aspartame

    Directory of Open Access Journals (Sweden)

    Samir H. Bouayad-Gervais

    2013-11-01

    Full Text Available The potential for dynamic chirality of an azapeptide nitrogen was examined by substitution of nitrogen for the α-carbon of the aspartate residue in the sweetener S,S-aspartame. Considering that S,S- and R,S-aspartame possess sweet and bitter tastes, respectively, a bitter-sweet taste of aza-aspartame 9 could be indicative of a low isomerization barrier for nitrogen chirality inter-conversion. Aza-aspartame 9 was synthesized by a combination of hydrazine and peptide chemistry. Crystallization of 9 indicated a R,S-configuration in the solid state; however, the aza-residue chiral center was considerably flattened relative to its natural amino acid counterpart. On tasting, the authors considered aza-aspartame 9 to be slightly bitter or tasteless. The lack of bitter sweet taste of aza-aspartame 9 may be due to flattening from sp2 hybridization in the urea as well as a high barrier for sp3 nitrogen inter-conversion, both of which may interfere with recognition by taste receptors.

  2. Examination of the potential for adaptive chirality of the nitrogen chiral center in aza-aspartame.

    Science.gov (United States)

    Bouayad-Gervais, Samir H; Lubell, William D

    2013-11-28

    The potential for dynamic chirality of an azapeptide nitrogen was examined by substitution of nitrogen for the α-carbon of the aspartate residue in the sweetener S,S-aspartame. Considering that S,S- and R,S-aspartame possess sweet and bitter tastes, respectively, a bitter-sweet taste of aza-aspartame 9 could be indicative of a low isomerization barrier for nitrogen chirality inter-conversion. Aza-aspartame 9 was synthesized by a combination of hydrazine and peptide chemistry. Crystallization of 9 indicated a R,S-configuration in the solid state; however, the aza-residue chiral center was considerably flattened relative to its natural amino acid counterpart. On tasting, the authors considered aza-aspartame 9 to be slightly bitter or tasteless. The lack of bitter sweet taste of aza-aspartame 9 may be due to flattening from sp2 hybridization in the urea as well as a high barrier for sp3 nitrogen inter-conversion, both of which may interfere with recognition by taste receptors.

  3. Enantioseparation of dansyl amino acids by ultra-high pressure liquid chromatography using cationic β-cyclodextrins as chiral additives.

    Science.gov (United States)

    Xiao, Yin; Tan, Timothy Thatt Yang; Ng, Siu-Choon

    2011-04-07

    This work reports the application of ultra-high pressure liquid chromatography (UHPLC) for reasonably fast enantiorecognition of some dansyl amino acids by employing three cationic β-cyclodextrins (β-CDs) as chiral additives. Good resolutions were obtained on an Agilent C18 column (2.1 mm i.d.; 1.8 μm; 50 mm length) with 1% (v/v) triethylammonium acetate buffered at pH 4.7 and acetonitrile as the mobile phase. Most of the analytes could be baseline resolved within 10 min. Increased cationic CD concentration or acetonitrile proportion in the mobile phase results in a decreased retention factor but accentuated selectivity. Furthermore, molecular mechanics calculation was performed and found to be consistent with the experimental results. © The Royal Society of Chemistry 2011

  4. Chiral ligand exchange high-speed countercurrent chromatography: mechanism, application and comparison with conventional liquid chromatography in enantioseparation of aromatic α-hydroxyl acids

    Science.gov (United States)

    Tong, Shengqiang; Shen, Mangmang; Cheng, Dongping; Ito, Yoichiro; Yan, Jizhong

    2014-01-01

    This work concentrates on the separation mechanism and application of chiral ligand exchange high-speed countercurrent chromatography (HSCCC) in enantioseparations, and comparison with traditional chiral ligand exchange high performance liquid chromatography (HPLC). The enantioseparation of ten aromatic α-hydroxyl acids were performed by these two chromatographic methods. Results showed that five of the racemates were successfully enantioseparated by HSCCC while only three of the racemates could be enantioseparated by HPLC using a suitable chiral ligand mobile phase additive. For HSCCC, the two-phase solvent system was composed of butanol-water (1:1, v/v), to which N-n-dodecyl-L-proline was added in the organic phase as chiral ligand and cupric acetate was added in the aqueous phase as a transition metal ion. Various operation parameters in HSCCC were optimized by enantioselective liquid-liquid extraction. Based on the results of the present studies the separation mechanism for HSCCC was proposed. For HPLC, the optimized mobile phase composed of aqueous solution containing 6 mmol L−1 L-phenylalanine and 3 mmol L−1 cupric sulfate and methanol was used for enantioseparation. Among three ligands tested on a conventional reverse stationary phase column, only one was found to be effective. In the present studies HSCCC presented unique advantages due to its high versatility of two-phase solvent systems and it could be used as an alternative method for enantioseparations. PMID:25087742

  5. Human face recognition ability is specific and highly heritable

    OpenAIRE

    Wilmer, Jeremy B.; Germine, Laura; Chabris, Christopher F.; Chatterjee, Garga; Williams, Mark; Loken, Eric; Nakayama, Ken; Duchaine, Bradley

    2010-01-01

    Compared with notable successes in the genetics of basic sensory transduction, progress on the genetics of higher level perception and cognition has been limited. We propose that investigating specific cognitive abilities with well-defined neural substrates, such as face recognition, may yield additional insights. In a twin study of face recognition, we found that the correlation of scores between monozygotic twins (0.70) was more than double the dizygotic twin correlation (0.29), evidence fo...

  6. Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

    International Nuclear Information System (INIS)

    Uzun, Lokman; Uzek, Recep; Şenel, Serap; Say, Ridvan; Denizli, Adil

    2013-01-01

    In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. Highlights: • Lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles • Direct incorporation of the fluorescent complex into polymeric backbone. • Imprinting by assistance of cupric ion coordination into nanoparticles • Evaluation of the chiral biorecognition ability of nanoparticles • Simultaneous selective separation and fluorescent monitoring

  7. Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Uzun, Lokman, E-mail: lokman@hacettepe.edu.tr [Hacettepe University, Department of Chemistry, 06381, Ankara (Turkey); Uzek, Recep; Şenel, Serap [Hacettepe University, Department of Chemistry, 06381, Ankara (Turkey); Say, Ridvan [Anadolu University, Department of Chemistry, 26470, Eskisehir (Turkey); Denizli, Adil [Hacettepe University, Department of Chemistry, 06381, Ankara (Turkey)

    2013-08-01

    In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. Highlights: • Lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles • Direct incorporation of the fluorescent complex into polymeric backbone. • Imprinting by assistance of cupric ion coordination into nanoparticles • Evaluation of the chiral biorecognition ability of nanoparticles • Simultaneous selective separation and fluorescent monitoring.

  8. Research Article. The Influence of Some Parameters on Chiral Separation of Ibuprofen by High-Performance Liquid Chromatography and Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Balint Alina

    2017-03-01

    Full Text Available Objective: The aim of the study was to compare the influence of mobile phase composition and temperature on chiral separation of racemic ibuprofen by capillary electrophoresis and high performance liquid chromatography with UV detection. Materials and methods: Racemic ibuprofen was analysed on a chiral OVM column with an HPLC system 1100 Agilent Technologies, under isocratic elution, by using potassium dihydrogen phosphate 20 mM and ethanol in mobile phase. The flow rate was set at 1 mL/min, UV detector at 220 nm and different column temperatures were tested. For electrophoresis separation an Agilent CE G1600AX Capillary Electrophoresis System system, with UV detection, was used. The electrophoresis analysis was performed at different pH values and temperatures, with phosphate buffer 25 mM and methyl-β-cyclodextrin as chiral selector. Results: The chromatograhic analysis reveals a high influence of mobile phase pH on ibuprofen enantiomers separation. An elution with a mixture of potassium dihydrogen phosphate 20 mM pH=3 and ethanol, at 25°C, allowed enantiomers separation with good resolution in less than 8 min. Conclusions: The proposed HPLC method proved suitable for the separation of ibuprofen enantiomers with a good resolution, but the capillary electrophoresis tested parameters did not allow chiral discrimination.

  9. High-emulation mask recognition with high-resolution hyperspectral video capture system

    Science.gov (United States)

    Feng, Jiao; Fang, Xiaojing; Li, Shoufeng; Wang, Yongjin

    2014-11-01

    We present a method for distinguishing human face from high-emulation mask, which is increasingly used by criminals for activities such as stealing card numbers and passwords on ATM. Traditional facial recognition technique is difficult to detect such camouflaged criminals. In this paper, we use the high-resolution hyperspectral video capture system to detect high-emulation mask. A RGB camera is used for traditional facial recognition. A prism and a gray scale camera are used to capture spectral information of the observed face. Experiments show that mask made of silica gel has different spectral reflectance compared with the human skin. As multispectral image offers additional spectral information about physical characteristics, high-emulation mask can be easily recognized.

  10. Chiral dynamics with (nonstrange quarks

    Directory of Open Access Journals (Sweden)

    Kubis Bastian

    2017-01-01

    Full Text Available We review the results and achievements of the project B.3. Topics addressed include pion photoproduction off the proton and off deuterium, three-flavor chiral perturbation theory studies, chiral symmetry tests in Goldstone boson decays, the development of unitarized chiral perturbation theory to next-to-leading order, the two-pole structure of the Λ(1405, the dynamical generation of the lowest S11 resonances, the theory of hadronic atoms and its application to various systems, precision studies in light-meson decays based on dispersion theory, the Roy–Steiner analysis of pion–nucleon scattering, a high-precision extraction of the elusive pion–nucleon σ-term, and aspects of chiral dynamics in few-nucleon systems.

  11. Chiral discrimination in nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Lazzeretti, Paolo

    2017-11-01

    Chirality is a fundamental property of molecules whose spatial symmetry is characterized by the absence of improper rotations, making them not superimposable to their mirror image. Chiral molecules constitute the elementary building blocks of living species and one enantiomer is favoured in general (e.g. L-aminoacids and D-sugars pervade terrestrial homochiral biochemistry) because most chemical reactions producing natural substances are enantioselective. Since the effect of chiral chemicals and drugs on living beings can be markedly different between enantiomers, the quest for practical spectroscopical methods to scrutinize chirality is an issue of great importance and interest. Nuclear magnetic resonance (NMR) is a topmost analytical technique, but spectrometers currently used are ‘blind’ to chirality, i.e. unable to discriminate the two mirror-image forms of a chiral molecule, because, in the absence of a chiral solvent, the spectral parameters, chemical shifts and spin-spin coupling constants are identical for enantiomers. Therefore, the development of new procedures for routine chiral recognition would offer basic support to scientists. However, in the presence of magnetic fields, a distinction between true and false chirality is mandatory. The former epitomizes natural optical activity, which is rationalized by a time-even pseudoscalar, i.e. the trace of a second-rank tensor, the mixed electric dipole/magnetic dipole polarizability. The Faraday effect, magnetic circular dichroism and magnetic optical activity are instead related to a time-odd axial vector. The present review summarizes recent theoretical and experimental efforts to discriminate enantiomers via NMR spectroscopy, with the focus on the deep connection between chirality and symmetry properties under the combined set of fundamental discrete operations, namely charge conjugation, parity (space inversion) and time (motion) reversal.

  12. Intrinsic chirality and prochirality at Air/R-(+)- and S-(-)-limonene interfaces: spectral signatures with interference chiral sum-frequency generation vibrational spectroscopy.

    Science.gov (United States)

    Fu, Li; Zhang, Yun; Wei, Zhe-Hao; Wang, Hong-Fei

    2014-09-01

    We report in this work detailed measurements of the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050 cm(-1)) of the air/liquid interfaces of R-(+)-limonene and S-(-)-limonene, using the recently developed high-resolution broadband sum-frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The achiral SFG spectra of R-limonene and S-limonene, as well as the RS racemic mixture (50/50 equal amount mixture), show that the corresponding molecular groups of the R and S enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit a spectral signature from the chiral response of the Cα-H stretching mode, and a spectral signature from the prochiral response of the CH(2) asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-(+)-limonene to S-(-)-limonene surfaces, and disappears for the RS racemic mixture surface. While the prochiral spectral feature of the CH(2) asymmetric stretching mode is the same for R-(+)-limonene and S-(-)-limonene surfaces, and also surprisingly remains the same for the RS racemic mixture surface. Therefore, the structures of the R-(+)-limonene and the S-(-)-limonene at the liquid interfaces are nevertheless not mirror images to each other, even though the corresponding groups have the same tilt angle from the interfacial normal, i.e., the R-(+)-limonene and the S-(-)-limonene at the surface are diastereomeric instead of enantiomeric. These results provide detailed information in understanding the structure and chirality of molecular interfaces and demonstrate the sensitivity and potential of SFG-VS as a unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface. © 2014 Wiley Periodicals, Inc.

  13. Probing chirality with a femtosecond reaction microscope

    Directory of Open Access Journals (Sweden)

    Janssen M. H. M.

    2013-03-01

    Full Text Available Detection of molecular chirality with high sensitivity and selectivity is important for many analytical and practical applications. Photoionization has emerged as a very sensitive probe of chirality in molecules. We show here that a table top setup with a femtosecond laser and a single imaging detector for both photoelectrons and photoions enables detection of chirality up to 3 orders of magnitude better than the existing conventional absorption based techniques.

  14. Social power and recognition of emotional prosody: High power is associated with lower recognition accuracy than low power.

    Science.gov (United States)

    Uskul, Ayse K; Paulmann, Silke; Weick, Mario

    2016-02-01

    Listeners have to pay close attention to a speaker's tone of voice (prosody) during daily conversations. This is particularly important when trying to infer the emotional state of the speaker. Although a growing body of research has explored how emotions are processed from speech in general, little is known about how psychosocial factors such as social power can shape the perception of vocal emotional attributes. Thus, the present studies explored how social power affects emotional prosody recognition. In a correlational study (Study 1) and an experimental study (Study 2), we show that high power is associated with lower accuracy in emotional prosody recognition than low power. These results, for the first time, suggest that individuals experiencing high or low power perceive emotional tone of voice differently. (c) 2016 APA, all rights reserved).

  15. 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.

  16. Chiral symmetry and chiral-symmetry breaking

    International Nuclear Information System (INIS)

    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

  17. Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles.

    Science.gov (United States)

    Uzun, Lokman; Uzek, Recep; Senel, Serap; Say, Ridvan; Denizli, Adil

    2013-08-01

    In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. High enantioselective Novozym 435-catalyzed esterification of (R,S)-flurbiprofen monitored with a chiral stationary phase.

    Science.gov (United States)

    Siódmiak, Tomasz; Mangelings, Debby; Vander Heyden, Yvan; Ziegler-Borowska, Marta; Marszałł, Michał Piotr

    2015-03-01

    Lipases form Candida rugosa and Candida antarctica were tested for their application in the enzymatic kinetic resolution of (R,S)-flurbiprofen by enantioselective esterification. Successful chromatographic separation with well-resolved peaks of (R)- and (S)-flurbiprofen and their esters was achieved in one run on chiral stationary phases by high-performance liquid chromatography (HPLC). In this study screening of enzymes was performed, and Novozym 435 was selected as an optimal catalyst for obtaining products with high enantiopurity. Additionally, the influence of organic solvents (dichloromethane, dichloroethane, dichloropropane, and methyl tert-butyl ether), primary alcohols (methanol, ethanol, n-propanol, and n-butanol), reaction time, and temperature on the enantiomeric ratio and conversion was tested. The high values of enantiomeric ratio (E in the range of 51.3-90.5) of the esterification of (R,S)-flurbiprofen were obtained for all tested alcohols using Novozym 435, which have a great significance in the field of biotechnological synthesis of drugs. The optimal temperature range for the performed reactions was from 37 to 45 °C. As a result of the optimization, (R)-flurbiprofen methyl ester was obtained with a high optical purity, eep = 96.3 %, after 96 h of incubation. The enantiomeric ratio of the reaction was E = 90.5 and conversion was C = 35.7 %.

  19. High-Level Event Recognition in Unconstrained Videos

    Science.gov (United States)

    2013-01-01

    frames per- forms well for urban soundscapes but not for polyphonic music. In place of GMM, Lu et al. [78] adopted spectral clustering to generate...Aucouturier JJ, Defreville B, Pachet F (2007) The bag-of-frames approach to audio pattern recognition: a sufficientmodel for urban soundscapes but not

  20. High-performance speech recognition using consistency modeling

    Science.gov (United States)

    Digalakis, Vassilios; Murveit, Hy; Monaco, Peter; Neumeyer, Leo; Sankar, Ananth

    1994-12-01

    The goal of SRI's consistency modeling project is to improve the raw acoustic modeling component of SRI's DECIPHER speech recognition system and develop consistency modeling technology. Consistency modeling aims to reduce the number of improper independence assumptions used in traditional speech recognition algorithms so that the resulting speech recognition hypotheses are more self-consistent and, therefore, more accurate. At the initial stages of this effort, SRI focused on developing the appropriate base technologies for consistency modeling. We first developed the Progressive Search technology that allowed us to perform large-vocabulary continuous speech recognition (LVCSR) experiments. Since its conception and development at SRI, this technique has been adopted by most laboratories, including other ARPA contracting sites, doing research on LVSR. Another goal of the consistency modeling project is to attack difficult modeling problems, when there is a mismatch between the training and testing phases. Such mismatches may include outlier speakers, different microphones and additive noise. We were able to either develop new, or transfer and evaluate existing, technologies that adapted our baseline genonic HMM recognizer to such difficult conditions.

  1. Host-Guest Inclusion Complexes between Amlodipine Enantiomers in the Biphasic Recognition Chiral Extraction System using Tartaric Acid and β-Cyclodextrin Derivatives as Positive Confirmation by using their Enantioselective Extraction.

    Science.gov (United States)

    Al Azzam, Khaldun M; Abdallah, Hassan H; Halim, Hairul N Abdul; Ahmad, Maizatul Akmam; Shaibah, Hassan

    2015-01-01

    The current work reports an extended theoretical study from our previous experimental work for the enantioselective extraction of amlodipine enantiomers in a biphasic recognition chiral extraction system (BRCES) consisting of hydrophobic D-diisopropyl tartrate dissolved in organic phase (n-decanol) and hydrophilic hydroxypropyl-β-cyclodextrin (HP-β-CD) in aqueous phase (acetate buffer) which preferentially recognize the R-enantiomer and S-enantiomer, respectively. The calculations were simulated using a semi-empirical PM3 method as a part of the Gaussian09 software package and were used to optimize the structures of the hosts, guests, and host-guest complexes in the gas phase without any restrictions. It was found that HP-β-CD has the strongest recognition ability among the three β-CD derivatives studied, namely HP-β-CD, hydroxyethyl-β-cyclodextrin (HE-β-CD), and methylated-β-cyclodextrin (Me-β-CD), due to the large interaction energies (Ecomp = -14.3025 kcal/ mol), while D-diisopropyl tartrate has the strongest ability among the four tartaric acid derivatives studied namely; L-diisopropyl tartrate, D-diisopropyl tartrate, L-diethyl tartrate, and D-diethyl tartrate (Ecomp = -5.9964 kcal/ mol). The computational calculations for the enantioselective partitioning of amlodipine enantiomers rationalized the reasons for the different behaviors for this extraction. The present theoretical results may be informative to scientists who are devoting themselves to developing models for their experimental parts or for enhancing the hydrophobic drug solubility in drug delivery systems.

  2. Host-Guest Inclusion Complexes between Amlodipine Enantiomers in the Biphasic Recognition Chiral Extraction System using Tartaric Acid and β-Cyclodextrin Derivatives as Positive Confirmation by using their Enantioselective Extraction

    Science.gov (United States)

    Al Azzam, Khaldun M.; Abdallah, Hassan H.; Halim, Hairul N. Abdul; Ahmad, Maizatul Akmam; Shaibah, Hassan

    2015-01-01

    The current work reports an extended theoretical study from our previous experimental work for the enantioselective extraction of amlodipine enantiomers in a biphasic recognition chiral extraction system (BRCES) consisting of hydrophobic D-diisopropyl tartrate dissolved in organic phase (n-decanol) and hydrophilic hydroxypropyl-β-cyclodextrin (HP-β-CD) in aqueous phase (acetate buffer) which preferentially recognize the R-enantiomer and S-enantiomer, respectively. The calculations were simulated using a semi-empirical PM3 method as a part of the Gaussian09 software package and were used to optimize the structures of the hosts, guests, and host-guest complexes in the gas phase without any restrictions. It was found that HP-β-CD has the strongest recognition ability among the three β-CD derivatives studied, namely HP-β-CD, hydroxyethyl-β-cyclodextrin (HE-β-CD), and methylated-β-cyclodextrin (Me-β-CD), due to the large interaction energies (Ecomp = −14.3025 kcal/ mol), while D-diisopropyl tartrate has the strongest ability among the four tartaric acid derivatives studied namely; L-diisopropyl tartrate, D-diisopropyl tartrate, L-diethyl tartrate, and D-diethyl tartrate (Ecomp = −5.9964 kcal/ mol). The computational calculations for the enantioselective partitioning of amlodipine enantiomers rationalized the reasons for the different behaviors for this extraction. The present theoretical results may be informative to scientists who are devoting themselves to developing models for their experimental parts or for enhancing the hydrophobic drug solubility in drug delivery systems. PMID:26839848

  3. On the use of spectral minutiae in high-resolution palmprint recognition

    NARCIS (Netherlands)

    Wang, Ruifang; Veldhuis, Raymond N.J.; Ramos, Daniel; Spreeuwers, Lieuwe Jan; Fierrez, Julian; Xu, H.

    2013-01-01

    The spectral minutiae representation has been proposed as a novel method to minutiae-based fingerprint recognition, which can handle minutiae translation and rotation and improve matching speed. As high-resolution palmprint recognition is also mainly based on minutiae sets, we apply spectral

  4. Chiral mirrors

    International Nuclear Information System (INIS)

    Plum, Eric; Zheludev, Nikolay I.

    2015-01-01

    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

  5. Recent progress of chiral stationary phases for separation of enantiomers in gas chromatography.

    Science.gov (United States)

    Xie, Sheng-Ming; Yuan, Li-Ming

    2017-01-01

    Chromatography techniques based on chiral stationary phases are widely used for the separation of enantiomers. In particular, gas chromatography has developed rapidly in recent years due to its merits such as fast analysis speed, lower consumption of stationary phases and analytes, higher column efficiency, making it a better choice for chiral separation in diverse industries. This article summarizes recent progress of novel chiral stationary phases based on cyclofructan derivatives and chiral porous materials including chiral metal-organic frameworks, chiral porous organic frameworks, chiral inorganic mesoporous materials, and chiral porous organic cages in gas chromatography, covering original research papers published since 2010. The chiral recognition properties and mechanisms of separation toward enantiomers are also introduced. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Chiral amine synthesis using ω-transaminases: an amine donor that displaces equilibria and enables high-throughput screening.

    Science.gov (United States)

    Green, Anthony P; Turner, Nicholas J; O'Reilly, Elaine

    2014-09-26

    The widespread application of ω-transaminases as biocatalysts for chiral amine synthesis has been hampered by fundamental challenges, including unfavorable equilibrium positions and product inhibition. Herein, an efficient process that allows reactions to proceed in high conversion in the absence of by-product removal using only one equivalent of a diamine donor (ortho-xylylenediamine) is reported. This operationally simple method is compatible with the most widely used (R)- and (S)-selective ω-TAs and is particularly suitable for the conversion of substrates with unfavorable equilibrium positions (e.g., 1-indanone). Significantly, spontaneous polymerization of the isoindole by-product generates colored derivatives, providing a high-throughput screening platform to identify desired ω-TA activity. © 2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  7. Helicity-Selective Phase-Matching and Quasi-Phase matching of Circularly Polarized High-Order Harmonics: Towards Chiral Attosecond Pulses

    Science.gov (United States)

    2016-05-23

    2 Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA 3Department of Physics and Optical Engineering, Ort Braude...polarized high harmonic generation, phase matching, ultrafast chiral physics, attosecond pulses (Some figures may appear in colour only in the online...temporal resolution and in spectral regions unavailable to circular polarization thus far. Acknowledgments This work was supported by the USA –Israel

  8. Chiral discrimination in biomimetic systems: Phenylalanine

    Indian Academy of Sciences (India)

    Chiral discrimination and recognition is important in peptide biosynthesis, amino acid synthesis and drug designing. Detailed structural information is available about the peptide synthesis in ribosome. However, no detailed study is available about the discrimination in peptide synthesis. We study the conformational energy ...

  9. A chiral sensor based on weak measurement for the determination of Proline enantiomers in diverse measuring circumstances.

    Science.gov (United States)

    Li, Dongmei; Guan, Tian; He, Yonghong; Liu, Fang; Yang, Anping; He, Qinghua; Shen, Zhiyuan; Xin, Meiguo

    2018-07-01

    A new chiral sensor based on weak measurement to accurately measure the optical rotation (OR) has been developed for the estimation of a trace amount of chiral molecule. With the principle of optical weak measurement in frequency domain, the central wavelength shift of output spectra is quantitatively relative to the angle of preselected polarization. Hence, a chiral molecule (e.g., L-amino acid, or D-amino acid) can be enantioselectively determined by modifying the preselection angle with the OR, which will cause the rotation of a polarization plane. The concentration of the chiral sample, corresponding to its optical activity, is quantitatively analyzed with the central wavelength shift of output spectra, which can be collected in real time. Immune to the refractive index change, the proposed chiral sensor is valid in complicated measuring circumstance. The detections of Proline enantiomer concentration in different solvents were implemented. The results demonstrated that weak measurement acted as a reliable method to chiral recognition of Proline enantiomers in diverse circumstance with the merits of high precision and good robustness. In addition, this real-time monitoring approach plays a crucial part in asymmetric synthesis and biological systems. Copyright © 2018. Published by Elsevier B.V.

  10. Light-front realization of chiral symmetry breaking

    International Nuclear Information System (INIS)

    Itakura, Kazunori; Maedan, Shinji

    2001-01-01

    We discuss a description of chiral symmetry breaking in the light-front (LF) formalism. Based on careful analyses of several modes, we give clear answers to the following three fundamental questions: (i) What is the difference between the LF chiral transformation and the ordinary chiral transformation? (ii) How does a gap equation for the chiral condensate emerge? (iii) What is the consequence of the coexistence of a nonzero chiral condensate and the trivial Fock vacuum? The answer to Question (i) is given through a classical analysis of each model. Question (ii) is answered based on our recognition of the importance of characteristic constraints, such as the zero-mode and fermionic constraints. Question (iii) is intimately related to another important problem, reconciliation of the nonzero chiral condensate ≠ 0 and the invariance of the vacuum under the LF chiral transformation Q 5 LF | 0> = 0. This and Question (iii) are understood in terms of the modified chiral transformation laws of the dependent variables. The characteristic ways in which the chiral symmetry breaking is realized are that the chiral charge Q 5 LF is no longer conserved and that the transformation of the scalar and pseudoscalar fields is modified. We also discuss other outcomes, such as the light-cone wave function of the pseudoscalar meson in the Nambu-Jona-Lasinio model. (author)

  11. The chiral bosonization in non-Abelian gauge theories

    International Nuclear Information System (INIS)

    Andrianov, A.A.; Novozhilov, Y.

    1985-01-01

    The chiral bosonization in non-Abelian gauge theories is described starting directly from the QCD functional. For a given mass scale Λ, the QCD may be equivalently represented by colour chiral fields, gauge fields and high energy fermions. The effective action for colour chiral fields may admit the existence of a colour Skyrmion-boson with the baryon number 2/3. (author)

  12. Enantiomeric determination of amino compounds with high sensitivity using the chiral reagents (+)- and (-)-1-(9-anthryl)-2-propyl chloroformate.

    Science.gov (United States)

    Thorsén, G; Engström, A; Josefsson, B

    1997-10-31

    New chiral precolumn reagents, (+)- and (-)-1-(9-anthryl)-2-propyl chloroformate (APOC), are introduced for the chiral separation of amino acids and small peptides in capillary electrophoresis. Chiral separation of 17 amino acids and four small peptides as their diastereomeric 1-(9-anthryl)-2-propyl carbamate derivatives have been achieved by micellar electrokinetic chromatography. The detection limit for the derivatives is in the femtomole range with UV detection and in the attomole range with laser-induced fluorescence (LIF) detection. LIF detection was used to determine the enantiomeric excess of four APOC-derivatised peptides. The use of the new, anthracene-based reagents in conjunction with argon ion LIF makes enantiomeric determinations at ppm levels feasible. In this paper determinations below promille levels are performed without overloading the separation system.

  13. Induction of Chirality in Two-Dimensional Nanomaterials: Chiral 2D MoS2 Nanostructures.

    Science.gov (United States)

    Purcell-Milton, Finn; McKenna, Robert; Brennan, Lorcan J; Cullen, Conor P; Guillemeney, Lilian; Tepliakov, Nikita V; Baimuratov, Anvar S; Rukhlenko, Ivan D; Perova, Tatiana S; Duesberg, Georg S; Baranov, Alexander V; Fedorov, Anatoly V; Gun'ko, Yurii K

    2018-02-27

    Two-dimensional (2D) nanomaterials have been intensively investigated due to their interesting properties and range of potential applications. Although most research has focused on graphene, atomic layered transition metal dichalcogenides (TMDs) and particularly MoS 2 have gathered much deserved attention recently. Here, we report the induction of chirality into 2D chiral nanomaterials by carrying out liquid exfoliation of MoS 2 in the presence of chiral ligands (cysteine and penicillamine) in water. This processing resulted in exfoliated chiral 2D MoS 2 nanosheets showing strong circular dichroism signals, which were far past the onset of the original chiral ligand signals. Using theoretical modeling, we demonstrated that the chiral nature of MoS 2 nanosheets is related to the presence of chiral ligands causing preferential folding of the MoS 2 sheets. There was an excellent match between the theoretically calculated and experimental spectra. We believe that, due to their high aspect ratio planar morphology, chiral 2D nanomaterials could offer great opportunities for the development of chiroptical sensors, materials, and devices for valleytronics and other potential applications. In addition, chirality plays a key role in many chemical and biological systems, with chiral molecules and materials critical for the further development of biopharmaceuticals and fine chemicals, and this research therefore should have a strong impact on relevant areas of science and technology such as nanobiotechnology, nanomedicine, and nanotoxicology.

  14. Chiral Magnetic Spirals

    International Nuclear Information System (INIS)

    Basar, Goekce; Dunne, Gerald V.; Kharzeev, Dmitri E.

    2010-01-01

    We argue that the presence of a very strong magnetic field in the chirally broken phase induces inhomogeneous expectation values, of a spiral nature along the magnetic field axis, for the currents of charge and chirality, when there is finite baryon density or an imbalance between left and right chiralities. This 'chiral magnetic spiral' is a gapless excitation transporting the currents of (i) charge (at finite chirality), and (ii) chirality (at finite baryon density) along the direction of the magnetic field. In both cases it also induces in the transverse directions oscillating currents of charge and chirality. In heavy ion collisions, the chiral magnetic spiral possibly provides contributions both to the out-of-plane and the in-plane dynamical charge fluctuations recently observed at BNL RHIC.

  15. Chiral Nuclear Dynamics II

    CERN Document Server

    Rho, Mannque

    2008-01-01

    This is the sequel to the first volume to treat in one effective field theory framework the physics of strongly interacting matter under extreme conditions. This is vital for understanding the high temperature phenomena taking place in relativistic heavy ion collisions and in the early Universe, as well as the high-density matter predicted to be present in compact stars. The underlying thesis is that what governs hadronic properties in a heat bath and/or a dense medium is hidden local symmetry which emerges from chiral dynamics of light quark systems and from the duality between QCD in 4D and

  16. High performance liquid chromatographic separation of thirteen drugs collected in Chinese Pharmacopoeia 2010(Ch.P2010 on cellulose ramification chiral stationary phase

    Directory of Open Access Journals (Sweden)

    Ying Zhou

    2012-02-01

    Full Text Available The enantiomers separation of thirteen drugs collected in Ch.P2010 was performed on chiral stationary phase of cellulose ramification (chiralpak OD and chiralpak OJ by high performance liquid chromatographic (HPLC methods, which included ibuprofen (C1, ketoprofen (C2, nitrendipine (C3, nimodipine (C4, felodipine (C5, omeprazole (C6, praziquantel (C7, propranolol hydrochloride (C8, atenolol (C9, sulpiride (C10, clenbuterol hydrochloride (C11, verapamil hydrochloride (C12, and chlorphenamine maleate (C13. The mobile phase consisted of isopropanol and n-hexane. The detection wavelength was set at 254 nm and the flow rate was 0.7 mL/min. The enantiomers separation of these thirteen racemates on chiralpak OD column and chiralpak OJ column was studied, while the effects of proportion of organic additives, alcohol displacer and temperature on the separation were studied. And the mechanism of some of racemates was discussed. The results indicated that thirteen chiral drugs could be separated on chiral stationary phase of cellulose ramification in normal phase chromatographic system. The chromatographic retention and resolution of enantiomers could be adjusted by factors including column temperature and the concentration of alcohol displacer and organic alkaline modifier in mobile phase. It was shown that the resolution was improved with reducing concentration of alcohol displacer. When concentration of organic alkaline modifier was 0.2% (v/v, the resolution and the peak shape were fairly good. Most racemates mentioned above had better resolution at column temperature of 25 °C. When racemates were separated, the temperature should be kept so as to obtain stable separation results. Keywords: HPLC, Chiral stationary phase, Optical enantiomers, Cellulose ramification

  17. Chiral ligand-exchange high-performance liquid chromatography with copper (II)-L-phenylalanine complexes for separation of 3,4-dimethoxy-α-methylphenylalanine racemes.

    Science.gov (United States)

    Jia, Dong-Xu; Ai, Zheng-Gui; Xue, Ya-Ping; Zheng, Yu-Guo

    2014-11-01

    L-3, 4-dimethoxy-α-methylphenylalanine (L-DMMD) is an important intermediate for the synthesis of 3-hydroxy-α-methyl-L-tyrosine (L-methyldopa). This paper describes an efficient, accurate, and low-priced method of high-performance liquid chromatography (HPLC) using chiral mobile phase and conventional C18 column to separate L-DMMD from its enantiomers. The effects of ligands, copper salts, organic modifiers, pHs of mobile phase, and temperatures on the retention factors (k') and selectivity (α) were evaluated to achieve optimal separation performance. Then, thermal analysis of the optimal separation conditions was investigated as well. It was confirmed that the optimal mobile phase was composed of 20 % (v/v) methanol, 8 mM L-phenylalanine (L-Phe), and 4 mM cupric sulfate in water of pH 3.2, and the column temperature was set at 20 °C. Baseline separation of two enantiomers could be obtained through the conventional C18 column with a resolution (R) of 3.18 in less than 18 min. Thermodynamic data (∆∆H and ∆∆S) obtained by Van't Hoff plots revealed the chiral separation was an enthalpy-controlled process. To the best of our knowledge, this is the first report regarding the enantioseparation of DMMD by chiral ligand-exchange HPLC.

  18. Highly Enantioselective Production of Chiral Secondary Alcohols Using Lactobacillus paracasei BD101 as a New Whole Cell Biocatalyst and Evaluation of Their Antimicrobial Effects.

    Science.gov (United States)

    Yılmaz, Durmuşhan; Şahin, Engin; Dertli, Enes

    2017-11-01

    Chiral secondary alcohols are valuable intermediates for many important enantiopure pharmaceuticals and biologically active molecules. In this work, we studied asymmetric reduction of aromatic ketones to produce the corresponding chiral secondary alcohols using lactic acid bacteria (LAB) as new biocatalysts. Seven LAB strains were screened for their ability to reduce acetophenones to their corresponding alcohols. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful at reducing the ketones to the corresponding alcohols. The reaction conditions were further systematically optimized for this strain and high enantioselectivity (99%) and very good yields were obtained. These secondary alcohols were further tested for their antimicrobial activities against important pathogens and significant levels of antimicrobial activities were observed although these activities were altered depending on the secondary alcohols as well as their enantiomeric properties. The current methodology demonstrates a promising and alternative green approach for the synthesis of chiral secondary alcohols of biological importance in a cheap, mild, and environmentally useful process. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  19. Introduction to Chiral Symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Volker [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-05-09

    These lectures are an attempt to a pedagogical introduction into the elementary concepts of chiral symmetry in nuclear physics. We will also discuss some effective chiral models such as the linear and nonlinear sigma model as well as the essential ideas of chiral perturbation theory. We will present some applications to the physics of ultrarelativistic heavy ion collisionsd.

  20. Introduction to chiral symmetry

    International Nuclear Information System (INIS)

    Koch, V.

    1996-01-01

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

  1. Chiral discotics; expression and amplification of chirality

    NARCIS (Netherlands)

    Brunsveld, L.; Meijer, E.W.; Rowan, A.E.; Nolte, R.J.M.; Denmark, S.E.; Nolte, R.J.M.; Meijer, E.W.

    2003-01-01

    In this contribution, chirality and discotic liquid crystals are discussed as a tool for studying the self-assembly of these molecules, both in solution and in the solid state. Therefore, the objective of this chapter is to summarize and elucidate how molecular chirality can be expressed in discotic

  2. Attention-Based Recurrent Temporal Restricted Boltzmann Machine for Radar High Resolution Range Profile Sequence Recognition

    Directory of Open Access Journals (Sweden)

    Yifan Zhang

    2018-05-01

    Full Text Available The High Resolution Range Profile (HRRP recognition has attracted great concern in the field of Radar Automatic Target Recognition (RATR. However, traditional HRRP recognition methods failed to model high dimensional sequential data efficiently and have a poor anti-noise ability. To deal with these problems, a novel stochastic neural network model named Attention-based Recurrent Temporal Restricted Boltzmann Machine (ARTRBM is proposed in this paper. RTRBM is utilized to extract discriminative features and the attention mechanism is adopted to select major features. RTRBM is efficient to model high dimensional HRRP sequences because it can extract the information of temporal and spatial correlation between adjacent HRRPs. The attention mechanism is used in sequential data recognition tasks including machine translation and relation classification, which makes the model pay more attention to the major features of recognition. Therefore, the combination of RTRBM and the attention mechanism makes our model effective for extracting more internal related features and choose the important parts of the extracted features. Additionally, the model performs well with the noise corrupted HRRP data. Experimental results on the Moving and Stationary Target Acquisition and Recognition (MSTAR dataset show that our proposed model outperforms other traditional methods, which indicates that ARTRBM extracts, selects, and utilizes the correlation information between adjacent HRRPs effectively and is suitable for high dimensional data or noise corrupted data.

  3. Diels-Alder cycloaddition strategy for kinetic resolution of chiral pyrazolidinones.

    Science.gov (United States)

    Sibi, Mukund P; Kawashima, Keisuke; Stanley, Levi M

    2009-09-03

    A rare example of the application of a catalytic, enantioselective Diels-Alder cycloaddition to affect a kinetic resolution has been developed. Chiral pyrazolidinones are resolved with high selectivity through a process that utilizes a relay of stereochemical information from a permanent chiral center to a fluxional chiral center to enhance the inherent selectivity of the chiral Lewis acid catalyst.

  4. High-speed cell recognition algorithm for ultrafast flow cytometer imaging system

    Science.gov (United States)

    Zhao, Wanyue; Wang, Chao; Chen, Hongwei; Chen, Minghua; Yang, Sigang

    2018-04-01

    An optical time-stretch flow imaging system enables high-throughput examination of cells/particles with unprecedented high speed and resolution. A significant amount of raw image data is produced. A high-speed cell recognition algorithm is, therefore, highly demanded to analyze large amounts of data efficiently. A high-speed cell recognition algorithm consisting of two-stage cascaded detection and Gaussian mixture model (GMM) classification is proposed. The first stage of detection extracts cell regions. The second stage integrates distance transform and the watershed algorithm to separate clustered cells. Finally, the cells detected are classified by GMM. We compared the performance of our algorithm with support vector machine. Results show that our algorithm increases the running speed by over 150% without sacrificing the recognition accuracy. This algorithm provides a promising solution for high-throughput and automated cell imaging and classification in the ultrafast flow cytometer imaging platform.

  5. Enantioseparation of linear and cyclic chiral bis(phenethyl)amines by means of cyclodextrin-modified capillary electrophoresis.

    Science.gov (United States)

    Wedig, M; Thunhorst, M; Laug, S; Decker, M; Lehmann, J; Holzgrabe, U

    2001-09-01

    For two years drugs introduced to the market have had- to be enantiomerically pure. Rapid and cheap methods of high reproducibility must, therefore, be available for evaluation of enantiomeric purity. Within the framework of a larger project dealing with chiral recognition of phenethylamines by means of native and derivatized cyclodextrins it was intended to find capillary electrophoresis methods suitable for separation of the enantiomers of chiral bis(phenethyl)amines and their corresponding cyclic analogues, within 10 min, using small amounts of a chiral selector, to save time and money. Heptakis(2,3-O-diacetyl-6-sulfato)beta-CD was found to be the most promising candidate most often fulfilling these requirements.

  6. 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)

  7. On chiral and non chiral 1D supermultiplets

    International Nuclear Information System (INIS)

    Toppan, Francesco

    2011-01-01

    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)

  8. Paternal kin recognition in the high frequency / ultrasonic range in a solitary foraging mammal

    Directory of Open Access Journals (Sweden)

    Kessler Sharon E

    2012-11-01

    Full Text Available Abstract Background Kin selection is a driving force in the evolution of mammalian social complexity. Recognition of paternal kin using vocalizations occurs in taxa with cohesive, complex social groups. This is the first investigation of paternal kin recognition via vocalizations in a small-brained, solitary foraging mammal, the grey mouse lemur (Microcebus murinus, a frequent model for ancestral primates. We analyzed the high frequency/ultrasonic male advertisement (courtship call and alarm call. Results Multi-parametric analyses of the calls’ acoustic parameters and discriminant function analyses showed that advertisement calls, but not alarm calls, contain patrilineal signatures. Playback experiments controlling for familiarity showed that females paid more attention to advertisement calls from unrelated males than from their fathers. Reactions to alarm calls from unrelated males and fathers did not differ. Conclusions 1 Findings provide the first evidence of paternal kin recognition via vocalizations in a small-brained, solitarily foraging mammal. 2 High predation, small body size, and dispersed social systems may select for acoustic paternal kin recognition in the high frequency/ultrasonic ranges, thus limiting risks of inbreeding and eavesdropping by predators or conspecific competitors. 3 Paternal kin recognition via vocalizations in mammals is not dependent upon a large brain and high social complexity, but may already have been an integral part of the dispersed social networks from which more complex, kin-based sociality emerged.

  9. Gelation induced supramolecular chirality: chirality transfer, amplification and application.

    Science.gov (United States)

    Duan, Pengfei; Cao, Hai; Zhang, Li; Liu, Minghua

    2014-08-14

    Supramolecular chirality defines chirality at the supramolecular level, and is generated from the spatial arrangement of component molecules assembling through non-covalent interactions such as hydrogen bonding, van der Waals interactions, π-π stacking, hydrophobic interactions and so on. During the formation of low molecular weight gels (LMWGs), one kind of fascinating soft material, one frequently encounters the phenomenon of chirality as well as chiral nanostructures, either from chiral gelators or even achiral gelators. A view of gelation-induced supramolecular chirality will be very helpful to understand the self-assembly process of the gelator molecules as well as the chiral structures, the regulation of the chirality in the gels and the development of the "smart" chiral materials such as chiroptical devices, catalysts and chiral sensors. It necessitates fundamental understanding of chirality transfer and amplification in these supramolecular systems. In this review, recent progress in gelation-induced supramolecular chirality is discussed.

  10. Mechanical separation of chiral dipoles by chiral light

    International Nuclear Information System (INIS)

    Canaguier-Durand, Antoine; Hutchison, James A; Genet, Cyriaque; Ebbesen, Thomas W

    2013-01-01

    We calculate optical forces and torques exerted on a chiral dipole by chiral light fields and reveal genuine chiral forces in combining the chiral contents of both light field and dipolar matter. Here, the optical chirality is characterized in a general way through the definition of optical chirality density and chirality flow. We show, in particular, that both terms have mechanical effects associated, respectively, with reactive and dissipative components of the chiral forces. Remarkably, these chiral force components are directly related to standard observables: optical rotation for the reactive component and circular dichroism for the dissipative one. As a consequence, the resulting forces and torques are dependent on the enantiomeric form of the chiral dipole. This suggests promising strategies for using chiral light forces to mechanically separate chiral objects according to their enantiomeric form. (paper)

  11. A chiral Brønsted acid-catalyzed highly enantioselective Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines.

    Science.gov (United States)

    Unhale, Rajshekhar A; Sadhu, Milon M; Ray, Sumit K; Biswas, Rayhan G; Singh, Vinod K

    2018-04-03

    A chiral phosphoric acid-catalyzed asymmetric Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines, derived from 3-hydroxyisoindolinones has been demonstrated in this communication. A variety of isoindolinone-based α-amino diazo esters bearing a quaternary stereogenic center were afforded in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee). Furthermore, the synthetic utility of the products has been depicted by the hydrogenation of the diazo moiety of adducts.

  12. Chiral perturbation theory

    International Nuclear Information System (INIS)

    Harada, Masayasu

    2009-01-01

    Chiral perturbation theory has been used for great number of phenomenological analyses in low energy QCD as well as the lattice QCD analyses since the creation of the theory by Weinberg in 1979 followed by its consolidation by Gasser and Leutwyler in 1984 and 85. The theory is now the highly established one as the approach based on the effective field theory to search for Green function including quantum correlations in the frame of the systematic expansion technique using Lagrangian which includes all of the terms allowed by the symmetry. This review has been intended to describe how systematically physical quantities are calculated in the framework of the chiral symmetry. Consequently many of the various phenomenological analyses are not taken up here for which other reports are to be referred. Further views are foreseen to be developed based on the theory in addition to numbers of results reported up to the present. Finally π-π scattering is taken up to discuss to what energy scale the theory is available. (S. Funahashi)

  13. Active chiral fluids.

    Science.gov (United States)

    Fürthauer, S; Strempel, M; Grill, S W; Jülicher, F

    2012-09-01

    Active processes in biological systems often exhibit chiral asymmetries. Examples are the chirality of cytoskeletal filaments which interact with motor proteins, the chirality of the beat of cilia and flagella as well as the helical trajectories of many biological microswimmers. Here, we derive constitutive material equations for active fluids which account for the effects of active chiral processes. We identify active contributions to the antisymmetric part of the stress as well as active angular momentum fluxes. We discuss four types of elementary chiral motors and their effects on a surrounding fluid. We show that large-scale chiral flows can result from the collective behavior of such motors even in cases where isolated motors do not create a hydrodynamic far field.

  14. Biocatalytic Synthesis of Chiral Pharmaceutical Intermediates

    Directory of Open Access Journals (Sweden)

    Ramesh N. Patel

    2004-01-01

    Full Text Available The production of single enantiomers of drug intermediates has become increasingly important in the pharmaceutical industry. Chiral intermediates and fine chemicals are in high demand from both the pharmaceutical and agrochemical industries for the preparation of bulk drug substances and agricultural products. The enormous potential of microorganisms and enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enantioselectivities has been demonstrated. In this article, biocatalytic processes are described for the synthesis of chiral pharmaceutical intermediates.

  15. Response surface methodology for the determination of the design space of enantiomeric separations on cinchona-based zwitterionic chiral stationary phases by high performance liquid chromatography.

    Science.gov (United States)

    Hanafi, Rasha Sayed; Lämmerhofer, Michael

    2018-01-26

    Quality-by-Design approach for enantioselective HPLC method development surpasses Quality-by-Testing in offering the optimal separation conditions with the least number of experiments and in its ability to describe the method's Design Space visually which helps to determine enantiorecognition to a significant extent. Although some schemes exist for enantiomeric separations on Cinchona-based zwitterionic stationary phases, the exact design space and the weights by which each of the chromatographic parameters influences the separation have not yet been statistically studied. In the current work, a screening design followed by a Response Surface Methodology optimization design were adopted for enantioseparation optimization of 3 model drugs namely the acidic Fmoc leucine, the amphoteric tryptophan and the basic salbutamol. The screening design proved that the acid/base additives are of utmost importance for the 3 chiral drugs, and that among 3 different pairs of acids and bases, acetic acid and diethylamine is the couple able to provide acceptable resolution at variable conditions. Visualization of the response surface of the retention factor, separation factor and resolution helped describe accurately the magnitude by which each chromatographic factor (% MeOH, concentration and ratio of acid base modifiers) affects the separation while interacting with other parameters. The global optima compromising highest enantioresolution with the least run time for the 3 chiral model drugs varied extremely, where it was best to set low % methanol with equal ratio of acid-base modifiers for the acidic drug, very high % methanol and 10-fold higher concentration of the acid for the amphoteric drug while 20 folds of the base modifier with moderate %methanol were needed for the basic drug. Considering the selected drugs as models for many series of structurally related compounds, the design space defined and the optimum conditions computed are the key for method development on

  16. Holographic memory for high-density data storage and high-speed pattern recognition

    Science.gov (United States)

    Gu, Claire

    2002-09-01

    As computers and the internet become faster and faster, more and more information is transmitted, received, and stored everyday. The demand for high density and fast access time data storage is pushing scientists and engineers to explore all possible approaches including magnetic, mechanical, optical, etc. Optical data storage has already demonstrated its potential in the competition against other storage technologies. CD and DVD are showing their advantages in the computer and entertainment market. What motivated the use of optical waves to store and access information is the same as the motivation for optical communication. Light or an optical wave has an enormous capacity (or bandwidth) to carry information because of its short wavelength and parallel nature. In optical storage, there are two types of mechanism, namely localized and holographic memories. What gives the holographic data storage an advantage over localized bit storage is the natural ability to read the stored information in parallel, therefore, meeting the demand for fast access. Another unique feature that makes the holographic data storage attractive is that it is capable of performing associative recall at an incomparable speed. Therefore, volume holographic memory is particularly suitable for high-density data storage and high-speed pattern recognition. In this paper, we review previous works on volume holographic memories and discuss the challenges for this technology to become a reality.

  17. Parity doublers in chiral potential quark models

    International Nuclear Information System (INIS)

    Kalashnikova, Yu. S.; Nefediev, A. V.; Ribeiro, J. E. F. T.

    2007-01-01

    The effect of spontaneous breaking of chiral symmetry over the spectrum of highly excited hadrons is addressed in the framework of a microscopic chiral potential quark model (Generalised Nambu-Jona-Lasinio model) with a vectorial instantaneous quark kernel of a generic form. A heavy-light quark-antiquark bound system is considered, as an example, and the Lorentz nature of the effective light-quark potential is identified to be a pure Lorentz-scalar, for low-lying states in the spectrum, and to become a pure spatial Lorentz vector, for highly excited states. Consequently, the splitting between the partners in chiral doublets is demonstrated to decrease fast in the upper part of the spectrum so that neighboring states of an opposite parity become almost degenerate. A detailed microscopic picture of such a 'chiral symmetry restoration' in the spectrum of highly excited hadrons is drawn and the corresponding scale of restoration is estimated

  18. Non-native Listeners’ Recognition of High-Variability Speech Using PRESTO

    Science.gov (United States)

    Tamati, Terrin N.; Pisoni, David B.

    2015-01-01

    Background Natural variability in speech is a significant challenge to robust successful spoken word recognition. In everyday listening environments, listeners must quickly adapt and adjust to multiple sources of variability in both the signal and listening environments. High-variability speech may be particularly difficult to understand for non-native listeners, who have less experience with the second language (L2) phonological system and less detailed knowledge of sociolinguistic variation of the L2. Purpose The purpose of this study was to investigate the effects of high-variability sentences on non-native speech recognition and to explore the underlying sources of individual differences in speech recognition abilities of non-native listeners. Research Design Participants completed two sentence recognition tasks involving high-variability and low-variability sentences. They also completed a battery of behavioral tasks and self-report questionnaires designed to assess their indexical processing skills, vocabulary knowledge, and several core neurocognitive abilities. Study Sample Native speakers of Mandarin (n = 25) living in the United States recruited from the Indiana University community participated in the current study. A native comparison group consisted of scores obtained from native speakers of English (n = 21) in the Indiana University community taken from an earlier study. Data Collection and Analysis Speech recognition in high-variability listening conditions was assessed with a sentence recognition task using sentences from PRESTO (Perceptually Robust English Sentence Test Open-Set) mixed in 6-talker multitalker babble. Speech recognition in low-variability listening conditions was assessed using sentences from HINT (Hearing In Noise Test) mixed in 6-talker multitalker babble. Indexical processing skills were measured using a talker discrimination task, a gender discrimination task, and a forced-choice regional dialect categorization task. Vocabulary

  19. Chiral high-performance liquid chromatographic analysis of fluoxetine and norfluoxetine in rabbit plasma, urine, and vitreous humor using an acetylated beta-cyclodextrin column.

    Science.gov (United States)

    Yee, L; Wong, S H; Skrinska, V A

    2000-10-01

    Fluoxetine (Prozac) is a potent selective serotonin reuptake inhibitor used for the treatment of major depression. Both fluoxetine (F) and its demethylated metabolite, norfluoxetine (NF), are racemic. S-Fluoxetine (SF) and S-norfluoxetine (SNF) are more potent inhibitors of serotonin reuptake than R-fluoxetine (RF) and R-norfluoxetine (RNF). Quantitation of individual enantiomers may provide a greater understanding of pharmacokinetic properties. The objective of this study was to perform a limited chiral selectivity study using rabbit plasma, urine, and vitreous humor analyzed by a solid-phase extraction protocol and a newly developed chiral analysis with an acetylated beta-cyclodextrin (CD) column. Liquid chromatographic parameters for CD were as follows: a mobile phase composition of methanol/0.3% triethylamine buffer, pH 5.6, (30:70), a flow rate of 1 mL/min, detection at 214 nm, and a temperature of 40 degrees C. Elution order was SNF, SF, RNF, and RF with capacity factors of 6, 7, 8, and 9, respectively. The corresponding resolution factors were as follows: R1,2 = 0.8, R2,3 = 1.2, and R3,4 = 0.9. The conditions for solid-phase extraction were optimized for Varian Bond Elut Certify columns. Following sample application, the column was rinsed with water, acetic acid, and then with methanol. Drug enantiomers were eluted with methylene chloride, isopropanol, and ammonium hydroxide (78:20:2). After extract evaporation, the extract residue was reconstituted for high-performance liquid chromatographic analysis. To investigate chiral pharmacology, a biodistribution study was performed by administering 2 mg/kg of F to five rabbits. Blood, urine, and vitreous specimens were collected. Plasma samples collected 45 min postinjection showed nearly equal concentrations of RF and SE After 24 h, the only metabolite detected in plasma was RNF. Drugs were not detectable in vitreous humor. Urine concentrations of SNF, SF, RNF, and RF were 51, 76, 34, and 8 microg/L, respectively

  20. Facial Emotion Recognition in Children with High Functioning Autism and Children with Social Phobia

    Science.gov (United States)

    Wong, Nina; Beidel, Deborah C.; Sarver, Dustin E.; Sims, Valerie

    2012-01-01

    Recognizing facial affect is essential for effective social functioning. This study examines emotion recognition abilities in children aged 7-13 years with High Functioning Autism (HFA = 19), Social Phobia (SP = 17), or typical development (TD = 21). Findings indicate that all children identified certain emotions more quickly (e.g., happy [less…

  1. Helical Polyacetylenes Induced via Noncovalent Chiral Interactions and Their Applications as Chiral Materials.

    Science.gov (United States)

    Maeda, Katsuhiro; Yashima, Eiji

    2017-08-01

    Construction of predominantly one-handed helical polyacetylenes with a desired helix sense utilizing noncovalent chiral interactions with nonracemic chiral guest compounds based on a supramolecular approach is described. As with the conventional dynamic helical polymers possessing optically active pendant groups covalently bonded to the polymer chains, this noncovalent helicity induction system can show significant chiral amplification phenomena, in which the chiral information of the nonracemic guests can transfer with high cooperativity through noncovalent bonding interactions to induce an almost single-handed helical conformation in the polymer backbone. An intriguing "memory effect" of the induced macromolecular helicity is observed for some polyacetylenes, which means that the helical conformations induced in dynamic helical polyacetylene can be transformed into metastable static ones by tuning their helix-inversion barriers. Potential applications of helical polyacetylenes with controlled helix sense constructed by the "noncovalent helicity induction and/or memory effect" as chiral materials are also described.

  2. Examining speed of processing of facial emotion recognition in individuals at ultra-high risk for psychosis

    DEFF Research Database (Denmark)

    Glenthøj, Louise Birkedal; Fagerlund, Birgitte; Bak, Nikolaj

    2018-01-01

    Emotion recognition is an aspect of social cognition that may be a key predictor of functioning and transition to psychosis in individuals at ultra-high risk (UHR) for psychosis ( Allott et al., 2014 ). UHR individuals exhibit deficits in accurately identifying facial emotions ( van Donkersgoed et...... al., 2015 ), but other potential anomalies in facial emotion recognition are largely unexplored. This study aimed to extend current knowledge on emotion recognition deficits in UHR individuals by examining: 1) whether UHR would display significantly slower facial emotion recognition than healthy...... controls, 2) whether an association between emotion recognition accuracy and emotion recognition latency is present in UHR, 3) the relationships between emotion recognition accuracy, neurocognition and psychopathology in UHR....

  3. Synergistic effects on enantioselectivity of zwitterionic chiral stationary phases for separations of chiral acids, bases, and amino acids by HPLC.

    Science.gov (United States)

    Hoffmann, Christian V; Pell, Reinhard; Lämmerhofer, Michael; Lindner, Wolfgang

    2008-11-15

    In an attempt to overcome the limited applicability scope of earlier proposed Cinchona alkaloid-based chiral weak anion exchangers (WAX) and recently reported aminosulfonic acid-based chiral strong cation exchangers (SCX), which are conceptionally restricted to oppositely charged solutes, their individual chiral selector (SO) subunits have been fused in a combinatorial synthesis approach into single, now zwitterionic, chiral SO motifs. The corresponding zwitterionic ion-exchange-type chiral stationary phases (CSPs) in fact combined the applicability spectra of the parent chiral ion exchangers allowing for enantioseparations of chiral acids and amine-type solutes in liquid chromatography using polar organic mode with largely rivaling separation factors as compared to the parent WAX and SCX CSPs. Furthermore, the application spectrum could be remarkably expanded to various zwitterionic analytes such as alpha- and beta-amino acids and peptides. A set of structurally related yet different CSPs consisting of either a quinine or quinidine alkaloid moiety as anion-exchange subunit and various chiral or achiral amino acids as cation-exchange subunits enabled us to derive structure-enantioselectivity relationships, which clearly provided strong unequivocal evidence for synergistic effects of the two oppositely charged ion-exchange subunits being involved in molecular recognition of zwitterionic analytes by zwitterionic SOs driven by double ionic coordination.

  4. Competitive chiral induction in a 2D molecular assembly: Intrinsic chirality versus coadsorber-induced chirality.

    Science.gov (United States)

    Chen, Ting; Li, Shu-Ying; Wang, Dong; Wan, Li-Jun

    2017-11-01

    Noncovalently introducing stereogenic information is a promising approach to embed chirality in achiral molecular systems. However, the interplay of the noncovalently introduced chirality with the intrinsic chirality of molecules or molecular aggregations has rarely been addressed. We report a competitive chiral expression of the noncovalent interaction-mediated chirality induction and the intrinsic stereogenic center-controlled chirality induction in a two-dimensional (2D) molecular assembly at the liquid/solid interface. Two enantiomorphous honeycomb networks are formed by the coassembly of an achiral 5-(benzyloxy)isophthalic acid (BIC) derivative and 1-octanol at the liquid/solid interface. The preferential formation of the globally homochiral assembly can be achieved either by using the chiral analog of 1-octanol, ( S )-6-methyl-1-octanol, as a chiral coadsorber to induce chirality to the BIC assembly via noncovalent hydrogen bonding or by covalently linking a chiral center in the side chain of BIC. Both the chiral coadsorber and the intrinsically chiral BIC derivative can act as a chiral seeds to induce a preferred handedness in the assembly of the achiral BIC derivatives. Furthermore, the noncovalent interaction-mediated chirality induction can restrain or even overrule the manifestation of the intrinsic chirality of the BIC molecule and dominate the handedness of the 2D molecular coassembly. This study provides insight into the interplay of intrinsically chiral centers and external chiral coadsorbers in the chiral induction, transfer, and amplification processes of 2D molecular assembly.

  5. Analytical Enantioseparation of β-Substituted-2-Phenylpropionic Acids by High-Performance Liquid Chromatography with Hydroxypropyl-β-Cyclodextrin as Chiral Mobile Phase Additive.

    Science.gov (United States)

    Tong, Shengqiang; Zhang, Hu; Yan, Jizhong

    2016-04-01

    Analytical enantioseparation of five β-substituted-2-phenylpropionic acids by high-performance liquid chromatography with hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral mobile phase additive was established in this paper, and chromatographic retention mechanism was studied. The effects of various factors such as the organic modifier, different ODS C18 columns and concentration of HP-β-CD were investigated. The chiral mobile phase was composed of methanol or acetonitrile and 0.5% triethylamine acetate buffer at pH 3.0 added with 25 mmol L(-1) of HP-β-CD, and baseline separations could be reached for all racemates. As for chromatographic retention mechanism, it was found that there was a negative correlation between the concentration of HP-β-CD in mobile phase and the retention factor under constant pH value and column temperature. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Zhang, Ping; Yu, Qian; He, Xiulong; Qian, Kun; Xiao, Wei; Xu, Zhifeng; Li, Tian; He, Lin

    2018-04-01

    The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum R s were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level. © 2017 Wiley Periodicals, Inc.

  7. Siegel's chiral boson and the chiral Schwinger model

    International Nuclear Information System (INIS)

    Berger, T.

    1992-01-01

    In this paper Siegel's proposal for a Lagrangian formulation of a chiral boson is analyzed by applying recent results on 2d chiral quantum gravity. A model is derived whose solution consists of a massive scalar and two massless chiral scalars. Therefore it is a minimally bosonized two-fermion chiral Schwinger model

  8. Evidence for Separate Contributions of High and Low Spatial Frequencies during Visual Word Recognition.

    Science.gov (United States)

    Winsler, Kurt; Holcomb, Phillip J; Midgley, Katherine J; Grainger, Jonathan

    2017-01-01

    Previous studies have shown that different spatial frequency information processing streams interact during the recognition of visual stimuli. However, it is a matter of debate as to the contributions of high and low spatial frequency (HSF and LSF) information for visual word recognition. This study examined the role of different spatial frequencies in visual word recognition using event-related potential (ERP) masked priming. EEG was recorded from 32 scalp sites in 30 English-speaking adults in a go/no-go semantic categorization task. Stimuli were white characters on a neutral gray background. Targets were uppercase five letter words preceded by a forward-mask (#######) and a 50 ms lowercase prime. Primes were either the same word (repeated) or a different word (un-repeated) than the subsequent target and either contained only high, only low, or full spatial frequency information. Additionally within each condition, half of the prime-target pairs were high lexical frequency, and half were low. In the full spatial frequency condition, typical ERP masked priming effects were found with an attenuated N250 (sub-lexical) and N400 (lexical-semantic) for repeated compared to un-repeated primes. For HSF primes there was a weaker N250 effect which interacted with lexical frequency, a significant reversal of the effect around 300 ms, and an N400-like effect for only high lexical frequency word pairs. LSF primes did not produce any of the classic ERP repetition priming effects, however they did elicit a distinct early effect around 200 ms in the opposite direction of typical repetition effects. HSF information accounted for many of the masked repetition priming ERP effects and therefore suggests that HSFs are more crucial for word recognition. However, LSFs did produce their own pattern of priming effects indicating that larger scale information may still play a role in word recognition.

  9. Observation of chiral phonons

    KAUST Repository

    Zhu, Hanyu; Yi, Jun; Li, Ming-yang; Xiao, Jun; Zhang, Lifa; Yang, Chih-Wen; Kaindl, Robert A.; Li, Lain-Jong; Wang, Yuan; Zhang, Xiang

    2018-01-01

    Chirality reveals symmetry breaking of the fundamental interaction of elementary particles. In condensed matter, for example, the chirality of electrons governs many unconventional transport phenomena such as the quantum Hall effect. Here we show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide. The broken inversion symmetry of the lattice lifts the degeneracy of clockwise and counterclockwise phonon modes at the corners of the Brillouin zone. We identified the phonons by the intervalley transfer of holes through hole-phonon interactions during the indirect infrared absorption, and we confirmed their chirality by the infrared circular dichroism arising from pseudoangular momentum conservation. The chiral phonons are important for electron-phonon coupling in solids, phonon-driven topological states, and energy-efficient information processing.

  10. Observation of chiral phonons

    KAUST Repository

    Zhu, Hanyu

    2018-02-01

    Chirality reveals symmetry breaking of the fundamental interaction of elementary particles. In condensed matter, for example, the chirality of electrons governs many unconventional transport phenomena such as the quantum Hall effect. Here we show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide. The broken inversion symmetry of the lattice lifts the degeneracy of clockwise and counterclockwise phonon modes at the corners of the Brillouin zone. We identified the phonons by the intervalley transfer of holes through hole-phonon interactions during the indirect infrared absorption, and we confirmed their chirality by the infrared circular dichroism arising from pseudoangular momentum conservation. The chiral phonons are important for electron-phonon coupling in solids, phonon-driven topological states, and energy-efficient information processing.

  11. Chiral dynamics with (non)strange quarks

    International Nuclear Information System (INIS)

    Kubis, Bastian; Meißner, Ulf-G.

    2017-01-01

    We review the results and achievements of the project B.3. Topics addressed include pion photoproduction off the proton and off deuterium, three-flavor chiral perturbation theory studies, chiral symmetry tests in Goldstone boson decays, the development of unitarized chiral perturbation theory to next-to-leading order, the two-pole structure of the Λ(1405), the dynamical generation of the lowest S_1_1 resonances, the theory of hadronic atoms and its application to various systems, precision studies in light-meson decays based on dispersion theory, the Roy–Steiner analysis of pion–nucleon scattering, a high-precision extraction of the elusive pion–nucleon σ-term, and aspects of chiral dynamics in few-nucleon systems.

  12. Chiral dynamics with (non)strange quarks

    Science.gov (United States)

    Kubis, Bastian; Meißner, Ulf-G.

    2017-01-01

    We review the results and achievements of the project B.3. Topics addressed include pion photoproduction off the proton and off deuterium, three-flavor chiral perturbation theory studies, chiral symmetry tests in Goldstone boson decays, the development of unitarized chiral perturbation theory to next-to-leading order, the two-pole structure of the Λ(1405), the dynamical generation of the lowest S11 resonances, the theory of hadronic atoms and its application to various systems, precision studies in light-meson decays based on dispersion theory, the Roy-Steiner analysis of pion-nucleon scattering, a high-precision extraction of the elusive pion-nucleon σ-term, and aspects of chiral dynamics in few-nucleon systems.

  13. Chiral Spirals from Discontinuous Chiral Symmetry

    Science.gov (United States)

    Kojo, Toru

    2014-09-01

    Recently phases of the inhomongeneous chiral condensates (IChC) attract renewed attentions in quark matter context. A number of theoretical studies have suggested that in some domain of moderate quark density the IChC phases are energetically more favored than the normal, chiral symmetric phase. In particular, the NJL-type model studies indicate that the phase of IChCs may mask the usual 1st order chiral phase transition line and its critical end point, and might change the conventional wisdom. In this talk, I will discuss characteristic features of the IChC phases and their potential impacts on the compact star physics. In particular, some of the IChC phases open gaps near the quark Fermi surface, suppressing back-reaction from the quark to gluon sectors. This mechanism delays the chiral restoration in the strange quark sector, forbids the emergence of the large bag constant, and as a consequence, makes the quark matter EOS very stiff. Recently phases of the inhomongeneous chiral condensates (IChC) attract renewed attentions in quark matter context. A number of theoretical studies have suggested that in some domain of moderate quark density the IChC phases are energetically more favored than the normal, chiral symmetric phase. In particular, the NJL-type model studies indicate that the phase of IChCs may mask the usual 1st order chiral phase transition line and its critical end point, and might change the conventional wisdom. In this talk, I will discuss characteristic features of the IChC phases and their potential impacts on the compact star physics. In particular, some of the IChC phases open gaps near the quark Fermi surface, suppressing back-reaction from the quark to gluon sectors. This mechanism delays the chiral restoration in the strange quark sector, forbids the emergence of the large bag constant, and as a consequence, makes the quark matter EOS very stiff. NSF Grants PHY09-69790, PHY13-05891.

  14. Geometrical approach to central molecular chirality: a chirality selection rule

    OpenAIRE

    Capozziello, S.; Lattanzi, A.

    2004-01-01

    Chirality is of primary importance in many areas of chemistry and has been extensively investigated since its discovery. We introduce here the description of central chirality for tetrahedral molecules using a geometrical approach based on complex numbers. According to this representation, for a molecule having n chiral centres, it is possible to define an index of chirality. Consequently a chirality selection rule has been derived which allows the characterization of a molecule as achiral, e...

  15. Relative quantification of enantiomers of chiral amines by high-throughput LC–ESI-MS/MS using isotopic variants of light and heavy L-pyroglutamic acids as the derivatization reagents

    International Nuclear Information System (INIS)

    Mochizuki, Toshiki; Taniguchi, Sayuri; Tsutsui, Haruhito; Min, Jun Zhe; Inoue, Koichi; Todoroki, Kenichiro; Toyo’oka, Toshimasa

    2013-01-01

    Highlights: ► Development of chiral labeling reagent for a pair of amine enantiomers. ► High-throughput analysis of diastereomers by UPLC–ESI-MS/MS. ► Highly efficient separation and detection of the enantiomers. ► Differential analysis of enantiomer ratio in different sample groups using light and heavy labeling reagents. -- Abstract: L-Pyroglutamic acid (L-PGA) was evaluated as a chiral labeling reagent for the enantioseparation of chiral amines in terms of separation efficiency by reversed-phase chromatography and detection sensitivity by ESI-MS/MS. Several amines and amino acid methyl esters were used as typical representatives of the chiral amines. Both enantiomers of the chiral amines were easily labeled with L-PGAs at room temperature for 60 min in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 1-hydroxy-1H-benzotriazole as the activation reagents. The resulting diastereomers were completely separated by reversed-phase chromatography using the small particle (1.7 μm) ODS column (Rs = 1.6–6.8). A highly sensitive detection at a low-fmol level (1–4 fmol) was also obtained from the multiple reaction monitoring (MRM) chromatograms. Therefore, a high-throughput determination was achieved by the present UPLC–ESI-MS/MS method. An isotope labeling strategy using light and heavy L-PGAs for the differential analysis of chiral amines in different sample groups was also proposed in this paper. As a model study, the differential analysis of the R and S ratio of 1-phenylethylamine (PEA) was performed according to the proposed procedure using light and heavy reagents, i.e., L-PGA and L-PGA-d 5 . The R/S ratio of PEA, spiked at the different concentrations in rat plasma, was almost similar to the theoretical values. Consequently, the proposed strategy using light and heavy chiral labeling reagents seems to be applicable for the differential analysis of chiral amine enantiomers in different sample groups, such as healthy persons and

  16. Gaze recognition in high-functioning autistic patients. Evidence from functional MRI

    International Nuclear Information System (INIS)

    Takebayashi, Hiroko; Ogai, Masahiro; Matsumoto, Hideo

    2006-01-01

    We examined whether patients with high-functioning autistic disorder (AD) would exhibit abnormal activation in brain regions implicated in the functioning of theory of mind (TOM) during gaze recognition. We investigated brain activity during gaze recognition in 5 patients with high-functioning AD and 9 normal subjects, using functional magnetic resonance imaging. On the gaze task, more activation was found in the left middle frontal gyrus, the right intraparietal sulcus, and the precentral and inferior parietal gyri bilaterally in controls than in AD patients, whereas the patient group showed more powerful signal changes in the left superior temporal gyrus, the right insula, and the right medial frontal gyrus. These results suggest that high-functioning AD patients have functional abnormalities not only in TOM-related brain regions, but also in widely distributed brain regions that are not normally activated upon the processing of information from another person's gaze. (author)

  17. High-Resolution Sonars: What Resolution Do We Need for Target Recognition?

    Directory of Open Access Journals (Sweden)

    Pailhas Yan

    2010-01-01

    Full Text Available Target recognition in sonar imagery has long been an active research area in the maritime domain, especially in the mine-counter measure context. Recently it has received even more attention as new sensors with increased resolution have been developed; new threats to critical maritime assets and a new paradigm for target recognition based on autonomous platforms have emerged. With the recent introduction of Synthetic Aperture Sonar systems and high-frequency sonars, sonar resolution has dramatically increased and noise levels decreased. Sonar images are distance images but at high resolution they tend to appear visually as optical images. Traditionally algorithms have been developed specifically for imaging sonars because of their limited resolution and high noise levels. With high-resolution sonars, algorithms developed in the image processing field for natural images become applicable. However, the lack of large datasets has hampered the development of such algorithms. Here we present a fast and realistic sonar simulator enabling development and evaluation of such algorithms.We develop a classifier and then analyse its performances using our simulated synthetic sonar images. Finally, we discuss sensor resolution requirements to achieve effective classification of various targets and demonstrate that with high resolution sonars target highlight analysis is the key for target recognition.

  18. Enantioselective determination of (R)-zopiclone and (S)-zopiclone (eszopiclone) in human hair by micropulverized extraction and chiral liquid chromatography/high resolution mass spectrometry.

    Science.gov (United States)

    Miyaguchi, Hajime; Kuwayama, Kenji

    2017-10-13

    Zopiclone and its (S)-enantiomer (eszopiclone) are commonly prescribed for insomnia. Despite the high demand for enantioselective differentiation, the chiral analysis of zopiclone in hair has not been reported. In this study, a method for the enantioselective quantification of zopiclone in human hair was developed. The extraction medium and duration were optimized using real eszopiclone-positive hair samples. Specifically, micropulverized extraction with 3.0M ammonium phosphate buffer (pH 8.4) involving salting-out assisted liquid-liquid extraction with acetonitrile was utilized to minimize the degradation of zopiclone and for rapid and facile operation. On the other hand, recovery of the conventional solid-liquid extraction involved overnight soaking in 3.0M ammonium phosphate buffer (pH 8.4) was only 0.58±0.12% of the maximum recovery achieved by the present method due to the decomposition in the phosphate buffer. An excellent chiral separation (Rs=5.0) was achieved using a chiral stationary phase comprising cellulose tris(3,5-dichlorophenylcarbamate) and a volatile mobile phase of 10mM ammonium carbonate (pH 8.0)-acetonitrile (25:75, v/v). Detection was carried out using liquid chromatography/high resolution mass spectrometry (LC/HRMS) with electrospray ionization. A Q Exactive mass spectrometer equipped with a quadrupole-Orbitrap analyzer was used for detection. The concentration of 0.50pg/mg was defined as the lowest limit of quantification using 5mg of hair sample. Using the developed approach, the concentration of eszopiclone in hair after a single 2-mg dose was found to be 441pg/mg, which was higher than all the reported values regarding a single administration of zopiclone. After daily administration of racemic zopiclone (3.75mg/day), the concentrations of (R)-enantiomer and (S)-enantiomer in the black hair were 5.30-8.31ng/mg and 7.96-12.8ng/mg, respectively, and the concentration of the (S)-enantiomer was always higher than that of the (R

  19. Facial Recognition of Happiness Is Impaired in Musicians with High Music Performance Anxiety.

    Science.gov (United States)

    Sabino, Alini Daniéli Viana; Camargo, Cristielli M; Chagas, Marcos Hortes N; Osório, Flávia L

    2018-01-01

    Music performance anxiety (MPA) can be defined as a lasting and intense apprehension connected with musical performance in public. Studies suggest that MPA can be regarded as a subtype of social anxiety. Since individuals with social anxiety have deficits in the recognition of facial emotion, we hypothesized that musicians with high levels of MPA would share similar impairments. The aim of this study was to compare parameters of facial emotion recognition (FER) between musicians with high and low MPA. 150 amateur and professional musicians with different musical backgrounds were assessed in respect to their level of MPA and completed a dynamic FER task. The outcomes investigated were accuracy, response time, emotional intensity, and response bias. Musicians with high MPA were less accurate in the recognition of happiness ( p  = 0.04; d  = 0.34), had increased response bias toward fear ( p  = 0.03), and increased response time to facial emotions as a whole ( p  = 0.02; d  = 0.39). Musicians with high MPA displayed FER deficits that were independent of general anxiety levels and possibly of general cognitive capacity. These deficits may favor the maintenance and exacerbation of experiences of anxiety during public performance, since cues of approval, satisfaction, and encouragement are not adequately recognized.

  20. Chiral bag model

    International Nuclear Information System (INIS)

    Musakhanov, M.M.

    1980-01-01

    The chiral bag model is considered. It is suggested that pions interact only with the surface of a quark ''bag'' and do not penetrate inside. In the case of a large bag the pion field is rather weak and goes to the linearized chiral bag model. Within that model the baryon mass spectrum, β decay axial constant, magnetic moments of baryons, pion-baryon coupling constants and their form factors are calculated. It is shown that pion corrections to the calculations according to the chiral bag model is essential. The obtained results are found to be in a reasonable agreement with the experimental data

  1. The covariant chiral ring

    Energy Technology Data Exchange (ETDEWEB)

    Bourget, Antoine; Troost, Jan [Laboratoire de Physique Théorique, École Normale Supérieure, 24 rue Lhomond, 75005 Paris (France)

    2016-03-23

    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{sup 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. 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 the formally equivalent problem of linearly polarized light incident on-axis on a non-chiral structure with index contrast. We derive analytical expressions for the first-order shifts of the band gaps for negligible index contrast. These are modified to give good approximations to the band gap shifts also...

  3. Illuminating the chirality of Weyl fermions

    Science.gov (United States)

    Ma, Qiong; Xu, Su-Yang; Chan, Ching-Kit; Zhang, Cheng-Long; Chang, Guoqing; Lin, Hsin; Jia, Shuang; Lee, Patrick; Gedik, Nuh; Jarillo-Herrero, Pablo

    In particle physics, Weyl fermions (WF) are elementary particles that travel at the speed of light and have a definite chirality. In condensed matter, it has been recently realized that WFs can arise as magnetic monopoles in the momentum space of a novel topological metal, the Weyl semimetal (WSM). Their chirality, given by the sign of the monopole charge, is the defining property of a WSM, since it directly serves as the topological number and gives rise to exotic properties such as Fermi arcs and the chiral anomaly. Moreover, the two chiralities, analogous to the two valleys in 2D materials, lead to a new degree of freedom in a 3D crystal, suggesting novel pathways to store and carry information. By shining circularly polarized light on the WSM TaAs, we illuminate the chirality of the WFs and achieve an electrical current that is highly controllable based on the WFs' chirality. Our results open up a wide range of new possibilities for experimentally studying and controlling the WFs and their associated quantum anomalies by optical and electrical means, which suggest the exciting prospect of ``Weyltronics''.

  4. Lattice modes of the chirally pure and racemic phases of tyrosine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Belyanchikov, M. A. [Moscow Institute of Physics and Technology (Russian Federation); Gorelik, V. S., E-mail: gorelik@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Gorshunov, B. P. [Moscow Institute of Physics and Technology (Russian Federation); Pyatyshev, A. Yu., E-mail: jb-valensia@mail.ru [Bauman Moscow State Technical University (Russian Federation)

    2017-01-15

    High-Q librational modes have been found to be present in the infrared absorption and Raman spectra of chirally pure L-tyrosine. Such modes can serve as terahertz radiation detectors and generators in chirally pure biostructures.

  5. Inexpensive chirality on the lattice

    International Nuclear Information System (INIS)

    Kamleh, W.; Williams, A.G.; Adams, D.

    2000-01-01

    Full text: Implementing lattice fermions that resemble as closely as possible continuum fermions is one of the main goals of the theoretical physics community. Aside from a lack of infinitely powerful computers, one of the main impediments to this is the Nielsen-Ninomiya No-Go theorem for chirality on the lattice. One of the consequences of this theorem is that exact chiral symmetry and a lack of fermion doublers cannot be simultaneously satisfied for fermions on the lattice. In the commonly used Wilson fermion formulation, chiral symmetry is explicitly sacrificed on the lattice to avoid fermion doubling. Recently, an alternative has come forward, namely, the Ginsparg-Wilson relation and one of its solutions, the Overlap fermion. The Ginsparg-Wilson relation is a statement of lattice-deformed chirality. The Overlap-Dirac operator is a member of the family of solutions of the Ginsparg-Wilson relation. In recent times, Overlap fermions have been of great interest to the community due to their excellent chiral properties. However, they are significantly more expensive to implement than Wilson fermions. This expense is primarily due to the fact that the Overlap implementation requires an evaluation of the sign function for the Wilson-Dirac operator. The sign function is approximated by a high order rational polynomial function, but this approximation is poor close to the origin. The less near-zero modes that the Wilson- Dirac operator possesses, the cheaper the Overlap operator will be to implement. A means of improving the eigenvalue properties of the Wilson-Dirac operator by the addition of a so-called 'Clover' term is put forward. Numerical results are given that demonstrate this improvement. The Nielsen-Ninomiya no-go theorem and chirality on the lattice are reviewed. The general form of solutions of the Ginsparg-Wilson relation are given, and the Overlap solution is discussed. Properties of the Overlap-Dirac operator are given, including locality and analytic

  6. Inversion of Supramolecular Chirality by Sonication-Induced Organogelation

    Science.gov (United States)

    Maity, Sibaprasad; Das, Priyadip; Reches, Meital

    2015-01-01

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

  7. Chiral near-fields around chiral dolmen nanostructure

    International Nuclear Information System (INIS)

    Fu, Tong; Wang, Tiankun; Chen, Yuyan; Wang, Yongkai; Qu, Yu; Zhang, Zhongyue

    2017-01-01

    Discriminating the handedness of the chiral molecule is of great importance in the field of pharmacology and biomedicine. Enhancing the chiral near-field is one way to increase the chiral signal of chiral molecules. In this paper, the chiral dolmen nanostructure (CDN) is proposed to enhance the chiral near-field. Numerical results show that the CDN can increase the optical chirality of the near-field by almost two orders of magnitude compared to that of a circularly polarized incident wave. In addition, the optical chirality of the near-field of the bonding mode is enhanced more than that of the antibonding mode. These results provide an effective method for tailoring the chiral near-field for biophotonics sensors. (paper)

  8. Chiral Gold Nanoclusters: Atomic Level Origins of Chirality.

    Science.gov (United States)

    Zeng, Chenjie; Jin, Rongchao

    2017-08-04

    Chiral nanomaterials have received wide interest in many areas, but the exact origin of chirality at the atomic level remains elusive in many cases. With recent significant progress in atomically precise gold nanoclusters (e.g., thiolate-protected Au n (SR) m ), several origins of chirality have been unveiled based upon atomic structures determined by using single-crystal X-ray crystallography. The reported chiral Au n (SR) m structures explicitly reveal a predominant origin of chirality that arises from the Au-S chiral patterns at the metal-ligand interface, as opposed to the chiral arrangement of metal atoms in the inner core (i.e. kernel). In addition, chirality can also be introduced by a chiral ligand, manifested in the circular dichroism response from metal-based electronic transitions other than the ligand's own transition(s). Lastly, the chiral arrangement of carbon tails of the ligands has also been discovered in a very recent work on chiral Au 133 (SR) 52 and Au 246 (SR) 80 nanoclusters. Overall, the origins of chirality discovered in Au n (SR) m nanoclusters may provide models for the understanding of chirality origins in other types of nanomaterials and also constitute the basis for the development of various applications of chiral nanoparticles. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Face Memory and Object Recognition in Children with High-Functioning Autism or Asperger Syndrome and in Their Parents

    Science.gov (United States)

    Kuusikko-Gauffin, Sanna; Jansson-Verkasalo, Eira; Carter, Alice; Pollock-Wurman, Rachel; Jussila, Katja; Mattila, Marja-Leena; Rahko, Jukka; Ebeling, Hanna; Pauls, David; Moilanen, Irma

    2011-01-01

    Children with Autism Spectrum Disorders (ASDs) have reported to have impairments in face, recognition and face memory, but intact object recognition and object memory. Potential abnormalities, in these fields at the family level of high-functioning children with ASD remains understudied despite, the ever-mounting evidence that ASDs are genetic and…

  10. Pure chiral optical fibres.

    Science.gov (United States)

    Poladian, L; Straton, M; Docherty, A; Argyros, A

    2011-01-17

    We investigate the properties of optical fibres made from chiral materials, in which a contrast in optical activity forms the waveguide, rather than a contrast in the refractive index; we refer to such structures as pure chiral fibres. We present a mathematical formulation for solving the modes of circularly symmetric examples of such fibres and examine the guidance and polarisation properties of pure chiral step-index, Bragg and photonic crystal fibre designs. Their behaviour is shown to differ for left- and right-hand circular polarisation, allowing circular polarisations to be isolated and/or guided by different mechanisms, as well as differing from equivalent non-chiral fibres. The strength of optical activity required in each case is quantified.

  11. Relativistic Chiral Kinetic Theory

    International Nuclear Information System (INIS)

    Stephanov, Mikhail

    2016-01-01

    This very brief review of the recent progress in chiral kinetic theory is based on the results of Refs. [J.-Y. Chen, D. T. Son, M. A. Stephanov, H.-U. Yee, Y. Yin, Lorentz Invariance in Chiral Kinetic Theory, Phys. Rev. Lett. 113 (18) (2014) 182302. doi: (10.1103/PhysRevLett.113.182302); J.-Y. Chen, D. T. Son, M. A. Stephanov, Collisions in Chiral Kinetic Theory, Phys. Rev. Lett. 115 (2) (2015) 021601. doi: (10.1103/PhysRevLett.115.021601); M. A. Stephanov, H.-U. Yee, The no-drag frame for anomalous chiral fluid, Phys. Rev. Lett. 116 (12) (2016) 122302. doi: (10.1103/PhysRevLett.116.122302)].

  12. Relativistic Chiral Kinetic Theory

    Energy Technology Data Exchange (ETDEWEB)

    Stephanov, Mikhail

    2016-12-15

    This very brief review of the recent progress in chiral kinetic theory is based on the results of Refs. [J.-Y. Chen, D. T. Son, M. A. Stephanov, H.-U. Yee, Y. Yin, Lorentz Invariance in Chiral Kinetic Theory, Phys. Rev. Lett. 113 (18) (2014) 182302. doi: (10.1103/PhysRevLett.113.182302); J.-Y. Chen, D. T. Son, M. A. Stephanov, Collisions in Chiral Kinetic Theory, Phys. Rev. Lett. 115 (2) (2015) 021601. doi: (10.1103/PhysRevLett.115.021601); M. A. Stephanov, H.-U. Yee, The no-drag frame for anomalous chiral fluid, Phys. Rev. Lett. 116 (12) (2016) 122302. doi: (10.1103/PhysRevLett.116.122302)].

  13. Baryon Chiral Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Becher,

    2002-08-08

    After contrasting the low energy effective theory for the baryon sector with one for the Goldstone sector, I use the example of pion nucleon scattering to discuss some of the progress and open issues in baryon chiral perturbation theory.

  14. Generalized chiral perturbation theory

    International Nuclear Information System (INIS)

    Knecht, M.; Stern, J.

    1994-01-01

    The Generalized Chiral Perturbation Theory enlarges the framework of the standard χPT (Chiral Perturbation Theory), relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, experimental tests of the foundations of the standard χPT become possible. Emphasis is put on physical aspects rather than on formal developments of GχPT. (author). 31 refs

  15. Generalized chiral membrane dynamics

    International Nuclear Information System (INIS)

    Cordero, R.; Rojas, E.

    2003-01-01

    We develop the dynamics of the chiral superconducting membranes (with null current) in an alternative geometrical approach. Besides of this, we show the equivalence of the resulting description with the one known Dirac-Nambu-Goto (DNG) case. Integrability for chiral string model is obtained using a proposed light-cone gauge. In a similar way, domain walls are integrated by means of a simple Ansatz. (Author)

  16. Extrinsic Cognitive Load Impairs Spoken Word Recognition in High- and Low-Predictability Sentences.

    Science.gov (United States)

    Hunter, Cynthia R; Pisoni, David B

    Listening effort (LE) induced by speech degradation reduces performance on concurrent cognitive tasks. However, a converse effect of extrinsic cognitive load on recognition of spoken words in sentences has not been shown. The aims of the present study were to (a) examine the impact of extrinsic cognitive load on spoken word recognition in a sentence recognition task and (b) determine whether cognitive load and/or LE needed to understand spectrally degraded speech would differentially affect word recognition in high- and low-predictability sentences. Downstream effects of speech degradation and sentence predictability on the cognitive load task were also examined. One hundred twenty young adults identified sentence-final spoken words in high- and low-predictability Speech Perception in Noise sentences. Cognitive load consisted of a preload of short (low-load) or long (high-load) sequences of digits, presented visually before each spoken sentence and reported either before or after identification of the sentence-final word. LE was varied by spectrally degrading sentences with four-, six-, or eight-channel noise vocoding. Level of spectral degradation and order of report (digits first or words first) were between-participants variables. Effects of cognitive load, sentence predictability, and speech degradation on accuracy of sentence-final word identification as well as recall of preload digit sequences were examined. In addition to anticipated main effects of sentence predictability and spectral degradation on word recognition, we found an effect of cognitive load, such that words were identified more accurately under low load than high load. However, load differentially affected word identification in high- and low-predictability sentences depending on the level of sentence degradation. Under severe spectral degradation (four-channel vocoding), the effect of cognitive load on word identification was present for high-predictability sentences but not for low

  17. Quenched chiral logarithms

    International Nuclear Information System (INIS)

    Sharpe, S.R.

    1992-04-01

    I develop a diagrammatic method for calculating chiral logarithms in the quenched approximation. While not rigorous, the method is based on physically reasonable assumptions, which can be tested by numerical simulations. The main results are that, at leading order in the chiral expansion, (a) there are no chiral logarithms in quenched f π m u = m d ; (b) the chiral logarithms in B K and related kaon B-parameters are, for m d = m s the same in the quenched approximation as in the full theory (c) for m π and the condensate, there are extra chiral logarithms due to loops containing the η', which lead to a peculiar non-analytic dependence of these quantities on the bare quark mass. Following the work of Gasser and Leutwyler, I discuss how there is a predictable finite volume dependence associated with each chiral logarithm. I compare the resulting predictions with numerical results: for most quantities the expected volume dependence is smaller than the errors. but for B V and B A there is an observed dependence which is consistent with the predictions

  18. Interwoven Patterns of Chirality Among Solar Structures: a Review

    Science.gov (United States)

    Martin, Sara F.

    2009-05-01

    Chirality is the handedness of solar magnetic structures as recognized in two dimensional solar images or in other solar data revealing distinct magnetic patterns. This review covers the historical succession of discoveries of the chirality of solar magnetic structures, beginning with left and right-handed helical magnetic clouds detected in many interplanetary coronal mass ejections. This led to the recognition of corresponding chiralities in coronal loop systems. Separately, chiral patterns in filaments, filament channels, sunspots, sigmoidal structures, and flare loop systems were established, interrelated, and linked to the chirality of coronal loop systems. The result was the finding that all solar chiral patterns fall into two and only two larger chiral systems with one system more prevalent in the northern hemisphere and the other in the southern hemisphere. From chiral characteristics, along with knowledge or assumptions about the magnetic field topology, we have the ability to better deduce the helicities characteristic of many solar structures. Traditionally, helicity is a property of magnetic fields with strict mathematical definitions in two well-known forms: twist and writhe. Application of the principle of the conservation of helicity to chiral systems now leads to more mature interpretations of the helicity of whole solar magnetic field systems as well as their components, which together must contain equivalent amounts of both left and right-handed helicity. From this broadened perspective, comes a better understanding of why right-handed coronal loops necessarily exist above filaments with left-handed barbs that always overly left-handed filament channels and vice versa. Along with this greater understanding, we are collectively at the point of learning to better recognize and predict the senses of roll, twist, and writhe in the axial fields of erupting prominences. These, in turn, confirm the signs of helicity in associated CMEs and magnetic clouds

  19. Search for chirality in 109Ag

    International Nuclear Information System (INIS)

    Timar, J.; Nyako, B.M.; Berek, G.; Gal, J.; Kalinka, G.; Krasznahorkay, A.; Molnar, J.; Zolnai, L.

    2007-01-01

    Complete text of publication follows. The existence of nuclear chirality is one of the most intriguing questions of contemporary high-spin nuclear structure studies. Rotational doublet-band candidates for chiral structures have been observed mostly in two regions of the nuclear chart: around 134 Pr, and around 104 Rh. In this second region chirality in the Rh isotopes are rather well studied, chiral doubling have also been observed in 100 Tc, however, results obtained for chirality in the studied Ag nuclei ( 105 Ag and 106 Ag) look rather contradictory. Thus, it is interesting to study these doublet bands in the nearby higher-mass Ag nuclei. In order to search for a chiral-candidate partner band to the yrast πg 9/2 v(h 11/2 ) 2 band in 109 Ag, high-spin states of this nucleus have been studied using the 96 Zr( 18 O,p4n) reaction. The experiment was performed at iThemba LABS using 8 Clover detectors of the AFRODITE array and the DIAMANT charged-particle array to detect the γ-rays and the charged particles, respectively. Altogether ∼140 million γγ-coincidence events were collected. Approximately 10 million events of them correspond to the reaction channel producing 109 Ag. No chiral candidate partner band has been found to the πg 9/2 v(h 11/2 ) 2 band with this statistics, however, the level scheme could be extended by several new levels and γ-transitions. A preliminary level scheme of 109 Ag obtained from the ongoing data analysis is shown in Fig. 1

  20. Hippocampal NMDA receptors are involved in rats' spontaneous object recognition only under high memory load condition.

    Science.gov (United States)

    Sugita, Manami; Yamada, Kazuo; Iguchi, Natsumi; Ichitani, Yukio

    2015-10-22

    The possible involvement of hippocampal N-methyl-D-aspartate (NMDA) receptors in spontaneous object recognition was investigated in rats under different memory load conditions. We first estimated rats' object memory span using 3-5 objects in "Different Objects Task (DOT)" in order to confirm the highest memory load condition in object recognition memory. Rats were allowed to explore a field in which 3 (3-DOT), 4 (4-DOT), or 5 (5-DOT) different objects were presented. After a delay period, they were placed again in the same field in which one of the sample objects was replaced by another object, and their object exploration behavior was analyzed. Rats could differentiate the novel object from the familiar ones in 3-DOT and 4-DOT but not in 5-DOT, suggesting that rats' object memory span was about 4. Then, we examined the effects of hippocampal AP5 infusion on performance in both 2-DOT (2 different objects were used) and 4-DOT. The drug treatment before the sample phase impaired performance only in 4-DOT. These results suggest that hippocampal NMDA receptors play a critical role in spontaneous object recognition only when the memory load is high. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Controlling the amplification of chirality in hydrogen-bonded assemblies

    NARCIS (Netherlands)

    Mateos timoneda, Miguel; Crego Calama, Mercedes; Reinhoudt, David

    2005-01-01

    The amplification of chirality (a high enantiomeric or diastereomeric excess induced by a small initial amount of chiral bias) on hydrogen-bonded assemblies has been studied using “sergeants-and-soldiers” experiments under thermodynamically controlled conditions. Here it is shown that different

  2. Asymmetric aza-Diels-Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

    Directory of Open Access Journals (Sweden)

    Pégot Bruce

    2006-09-01

    Full Text Available Abstract The asymmetric aza-Diels-Alder reaction of chiral imines with Danishefsky's diene in chiral ionic liquids provides the corresponding cycloadduct with moderate to high diastereoselectivity. The reaction has proved to perform better at room temperature in ionic liquids without either Lewis acid catalyst or organic solvent. Chiral ionic liquids are recycled while their efficiency is preserved.

  3. Enantiopure Ferrocene-Based Planar-Chiral Iridacycles: Stereospecific Control of Iridium-Centred Chirality.

    Science.gov (United States)

    Arthurs, Ross A; Ismail, Muhammad; Prior, Christopher C; Oganesyan, Vasily S; Horton, Peter N; Coles, Simon J; Richards, Christopher J

    2016-02-24

    Reaction of [IrCp*Cl2 ]2 with ferrocenylimines (Fc=NAr, Ar=Ph, p-MeOC6 H4 ) results in ferrocene C-H activation and the diastereoselective synthesis of half-sandwich iridacycles of relative configuration Sp *,RIr *. Extension to (S)-2-ferrocenyl-4-(1-methylethyl)oxazoline gave highly diastereoselective control over the new elements of planar chirality and metal-based pseudo-tetrahedral chirality, to give both neutral and cationic half-sandwich iridacycles of absolute configuration Sc ,Sp ,RIr . Substitution reactions proceed with retention of configuration, with the planar chirality controlling the metal-centred chirality through an iron-iridium interaction in the coordinatively unsaturated cationic intermediate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 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.

  5. Autoamplification of molecular chirality through the induction of supramolecular chirality

    NARCIS (Netherlands)

    van Dijken, Derk Jan; Beierle, John M.; Stuart, Marc C. A.; Szymanski, Wiktor; Browne, Wesley R.; Feringa, Ben L.

    2014-01-01

    The novel concept for the autoamplification of molecular chirality, wherein the amplification proceeds through the induction of supramolecular chirality, is presented. A solution of prochiral, ring-open diarylethenes is doped with a small amount of their chiral, ring-closed counterpart. The

  6. Movement recognition technology as a method of assessing spontaneous general movements in high risk infants

    Directory of Open Access Journals (Sweden)

    Claire eMarcroft

    2015-01-01

    Full Text Available Preterm birth is associated with increased risks of neurological and motor impairments such as cerebral palsy. The risks are highest in those born at the lowest gestations. Early identification of those most at risk is challenging meaning that a critical window of opportunity to improve outcomes through therapy-based interventions may be missed. Clinically, the assessment of spontaneous general movements is an important tool which can be used for the prediction of movement impairments in high risk infants.Movement recognition aims to capture and analyze relevant limb movements through computerized approaches focusing on continuous, objective, and quantitative assessment. Different methods of recording and analyzing infant movements have recently been explored in high risk infants. These range from camera-based solutions to body-worn miniaturized movement sensors used to record continuous time-series data that represent the dynamics of limb movements. Various machine learning methods have been developed and applied to the analysis of the recorded movement data. This analysis has focused on the detection and classification of atypical spontaneous general movements. This paper aims to identify recent translational studies using movement recognition technology as a method of assessing movement in high risk infants. The application of this technology within pediatric practice represents a growing area of inter-disciplinary collaboration which may lead to a greater understanding of the development of the nervous system in infants at high risk of motor impairment.

  7. Algebraic study of chiral anomalies

    Indian Academy of Sciences (India)

    Chiral anomalies; gauge theories; bundles; connections; quantum field ... The algebraic structure of chiral anomalies is made globally valid on non-trivial bundles by the introduction of a fixed background connection. ... Current Issue : Vol.

  8. Silver Films with Hierarchical Chirality.

    Science.gov (United States)

    Ma, Liguo; Cao, Yuanyuan; Duan, Yingying; Han, Lu; Che, Shunai

    2017-07-17

    Physical fabrication of chiral metallic films usually results in singular or large-sized chirality, restricting the optical asymmetric responses to long electromagnetic wavelengths. The chiral molecule-induced formation of silver films prepared chemically on a copper substrate through a redox reaction is presented. Three levels of chirality were identified: primary twisted nanoflakes with atomic crystal lattices, secondary helical stacking of these nanoflakes to form nanoplates, and tertiary micrometer-sized circinates consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption- and scattering-based optical activities at UV/Vis wavelengths based on their hierarchical chirality. The Ag films showed chiral selectivity for amino acids in catalytic electrochemical reactions, which originated from their primary atomic crystal lattices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Chiral anomalies and differential geometry

    International Nuclear Information System (INIS)

    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

  10. Neural nets with varying topology for high energy particle recognition. Theory and applications

    International Nuclear Information System (INIS)

    Perrone, A.L.; Basti, G.; Messi, R.; Paoluzi, L.; Picozza, P.

    1995-01-01

    In this paper we propose a strategy to solve the problem of parallel compuation based on a dynamic definition of the net topology showing its effectiveness for problems of particle track recognition in high-energy physics. In this way, we can maintain the linear architecture like in the geometric perceptron, but with a partial and dynamic connectivity so to overcome the intrinsic limiations of the geometric perceptron. Namely, the computation is truly parallel because of the partial connectivity but the net topology is always the optimal one because of its dynamic redefinition on the single input pattern. For these properties, we call this new architecture dynamic perceptron

  11. Chirality sensing with stereodynamic biphenolate zinc complexes.

    Science.gov (United States)

    Bentley, Keith W; de Los Santos, Zeus A; Weiss, Mary J; Wolf, Christian

    2015-10-01

    Two bidentate ligands consisting of a fluxional polyarylacetylene framework with terminal phenol groups were synthesized. Reaction with diethylzinc gives stereodynamic complexes that undergo distinct asymmetric transformation of the first kind upon binding of chiral amines and amino alcohols. The substrate-to-ligand chirality imprinting at the zinc coordination sphere results in characteristic circular dichroism signals that can be used for direct enantiomeric excess (ee) analysis. This chemosensing approach bears potential for high-throughput ee screening with small sample amounts and reduced solvent waste compared to traditional high-performance liquid chromatography methods. © 2015 Wiley Periodicals, Inc.

  12. High Speed Railway Environment Safety Evaluation Based on Measurement Attribute Recognition Model

    Directory of Open Access Journals (Sweden)

    Qizhou Hu

    2014-01-01

    Full Text Available In order to rationally evaluate the high speed railway operation safety level, the environmental safety evaluation index system of high speed railway should be well established by means of analyzing the impact mechanism of severe weather such as raining, thundering, lightning, earthquake, winding, and snowing. In addition to that, the attribute recognition will be identified to determine the similarity between samples and their corresponding attribute classes on the multidimensional space, which is on the basis of the Mahalanobis distance measurement function in terms of Mahalanobis distance with the characteristics of noncorrelation and nondimensionless influence. On top of the assumption, the high speed railway of China environment safety situation will be well elaborated by the suggested methods. The results from the detailed analysis show that the evaluation is basically matched up with the actual situation and could lay a scientific foundation for the high speed railway operation safety.

  13. State Recognition of High Voltage Isolation Switch Based on Background Difference and Iterative Search

    Science.gov (United States)

    Xu, Jiayuan; Yu, Chengtao; Bo, Bin; Xue, Yu; Xu, Changfu; Chaminda, P. R. Dushantha; Hu, Chengbo; Peng, Kai

    2018-03-01

    The automatic recognition of the high voltage isolation switch by remote video monitoring is an effective means to ensure the safety of the personnel and the equipment. The existing methods mainly include two ways: improving monitoring accuracy and adopting target detection technology through equipment transformation. Such a method is often applied to specific scenarios, with limited application scope and high cost. To solve this problem, a high voltage isolation switch state recognition method based on background difference and iterative search is proposed in this paper. The initial position of the switch is detected in real time through the background difference method. When the switch starts to open and close, the target tracking algorithm is used to track the motion trajectory of the switch. The opening and closing state of the switch is determined according to the angle variation of the switch tracking point and the center line. The effectiveness of the method is verified by experiments on different switched video frames of switching states. Compared with the traditional methods, this method is more robust and effective.

  14. 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

  15. Holographic Chiral Magnetic Spiral

    International Nuclear Information System (INIS)

    Kim, Keun-Young; Sahoo, Bindusar; Yee, Ho-Ung

    2010-06-01

    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)

  16. Atropisomerism: the effect of the axial chirality in bioactive compounds; Atropoisomerismo: o efeito da quiralidade axial em substancias bioativas

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Anderson Rouge dos; Pinheiro, Alessandra Campbell; Sodero, Ana Carolina Renno; Cunha, Andrea Sousa da; Padilha, Monica Costa; Sousa, Priscila Mesquita de; Fontes, Silvia Paredes [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Organica; Veloso, Marcia Paranho [Universidade Federal de Alfenas, MG (Brazil); Fraga, Carlos Alberto Manssour [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Faculdade de Farmacia. Lab. de Avaliacao e Sintese de Substancias Bioativas (LASSBio)]. E-mail: cmfraga@pharma.ufrj.br

    2007-01-15

    Atropisomerism is a special kind of stereoisomeric relationship that arises from the freezing of a certain conformation of an organic molecule, associated with a high rotational barrier about a single covalent bond. Atropisomerism has been originally described in orto-functionalized biphenyl derivatives, but a lot of other organic functionalities can present this structural phenomenon, characterized by the presence of chiral properties in compounds that do not present classical stereogenic centers. Atropisomeric compounds, intermediates and catalysts have well-know importance in organic synthesis, but the influence of the axial chirality in substances able to modulate biological systems is still not very exploited in drug design and development. In this context, the present account describes the importance of this structural property in the medicinal chemistry of different classes of bioactive compounds or therapeutic agents, emphasizing how atropisomerism could affect the molecular recognition of a ligand or a prototype by the target bioreceptor. (author)

  17. Chiral perturbation theory

    International Nuclear Information System (INIS)

    Ecker, G.

    1996-06-01

    After a general introduction to the structure of effective field theories, the main ingredients of chiral perturbation theory are reviewed. Applications include the light quark mass ratios and pion-pion scattering to two-loop accuracy. In the pion-nucleon system, the linear σ model is contrasted with chiral perturbation theory. The heavy-nucleon expansion is used to construct the effective pion-nucleon Lagrangian to third order in the low-energy expansion, with applications to nucleon Compton scattering. (author)

  18. Compact Representation of High-Dimensional Feature Vectors for Large-Scale Image Recognition and Retrieval.

    Science.gov (United States)

    Zhang, Yu; Wu, Jianxin; Cai, Jianfei

    2016-05-01

    In large-scale visual recognition and image retrieval tasks, feature vectors, such as Fisher vector (FV) or the vector of locally aggregated descriptors (VLAD), have achieved state-of-the-art results. However, the combination of the large numbers of examples and high-dimensional vectors necessitates dimensionality reduction, in order to reduce its storage and CPU costs to a reasonable range. In spite of the popularity of various feature compression methods, this paper shows that the feature (dimension) selection is a better choice for high-dimensional FV/VLAD than the feature (dimension) compression methods, e.g., product quantization. We show that strong correlation among the feature dimensions in the FV and the VLAD may not exist, which renders feature selection a natural choice. We also show that, many dimensions in FV/VLAD are noise. Throwing them away using feature selection is better than compressing them and useful dimensions altogether using feature compression methods. To choose features, we propose an efficient importance sorting algorithm considering both the supervised and unsupervised cases, for visual recognition and image retrieval, respectively. Combining with the 1-bit quantization, feature selection has achieved both higher accuracy and less computational cost than feature compression methods, such as product quantization, on the FV and the VLAD image representations.

  19. Confining but chirally symmetric dense and cold matter

    International Nuclear Information System (INIS)

    Glozman, L. Ya.

    2012-01-01

    The possibility for existence of cold, dense chirally symmetric matter with confinement is reviewed. The answer to this question crucially depends on the mechanism of mass generation in QCD and interconnection of confinement and chiral symmetry breaking. This question can be clarified from spectroscopy of hadrons and their axial properties. Almost systematical parity doubling of highly excited hadrons suggests that their mass is not related to chiral symmetry breaking in the vacuum and is approximately chirally symmetric. Then there is a possibility for existence of confining but chirally symmetric matter. We clarify a possible mechanism underlying such a phase at low temperatures and large density. Namely, at large density the Pauli blocking prevents the gap equation to generate a solution with broken chiral symmetry. However, the chirally symmetric part of the quark Green function as well as all color non-singlet quantities are still infrared divergent, meaning that the system is with confinement. A possible phase transition to such a matter is most probably of the first order. This is because there are no chiral partners to the lowest lying hadrons.

  20. Chirality: from QCD to condensed matter

    International Nuclear Information System (INIS)

    Kharzeev, D.

    2015-01-01

    This lecture is about chirality and consists of 4 parts. In the first part a general introduction of chirality is given and its implementation in nuclear and particle physics, in particular the chiral magnetic effect, as well as Chirality in quantum materials (CME, optoelectronics, photonics) are discussed. The 2nd lecture is about the chiral magnetic effect. The 3rd lecture deals with the chiral magnetic effect and hydrodynamics and the last part with chirality and light. (nowak)

  1. Chiral algebras for trinion theories

    International Nuclear Information System (INIS)

    Lemos, Madalena; Peelaers, Wolfger

    2015-01-01

    It was recently understood that one can identify a chiral algebra in any four-dimensional N=2 superconformal theory. In this note, we conjecture the full set of generators of the chiral algebras associated with the T n theories. The conjecture is motivated by making manifest the critical affine module structure in the graded partition function of the chiral algebras, which is computed by the Schur limit of the superconformal index for T n theories. We also explicitly construct the chiral algebra arising from the T 4 theory. Its null relations give rise to new T 4 Higgs branch chiral ring relations.

  2. Chiral Plasmonic Nanostructures Fabricated by Circularly Polarized Light.

    Science.gov (United States)

    Saito, Koichiro; Tatsuma, Tetsu

    2018-05-09

    The chirality of materials results in a wide variety of advanced technologies including image display, data storage, light management including negative refraction, and enantioselective catalysis and sensing. Here, we introduce chirality to plasmonic nanostructures by using circularly polarized light as the sole chiral source for the first time. Gold nanocuboids as precursors on a semiconductor were irradiated with circularly polarized light to localize electric fields at specific corners of the cuboids depending on the handedness of light and deposited dielectric moieties as electron oscillation boosters by the localized electric field. Thus, plasmonic nanostructures with high chirality were developed. The present bottom-up method would allow the large-scale and cost-effective fabrication of chiral materials and further applications to functional materials and devices.

  3. Asymmetric Michael Addition Mediated by Chiral Ionic Liquids

    Science.gov (United States)

    Suzuki, Yumiko

    2018-01-01

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

  4. Asymmetric Michael Addition Mediated by Chiral Ionic Liquids.

    Science.gov (United States)

    Suzuki, Yumiko

    2018-06-01

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

  5. A quantitative measure of chirality inside nucleic acid databank.

    Science.gov (United States)

    Pietropaolo, Adriana; Parrinello, Michele

    2011-08-01

    We show the capability of a chirality index (Pietropaolo et al., Proteins 2008;70:667-677) to investigate nucleic acid structures because of its high sensitivity to helical conformations. By analyzing selected structures of DNA and RNA, we have found that sequences rich in cytosine and guanine have a tendency to left-handed chirality, in contrast to regions rich in adenine or thymine which show strong negative, right-handed, chirality values. We also analyze RNA structures, where specific loops and hairpin motifs are characterized by a well-defined chirality value. We find that in nucleosome the chirality is exalted, whereas in ribosome it is reduced. Our results illustrate the sensitivity of this descriptor for nucleic acid conformations. Copyright © 2011 Wiley-Liss, Inc.

  6. Alternative Experimental Evidence for Chiral Restoration in Excited Baryons

    International Nuclear Information System (INIS)

    Glozman, L. Ya.

    2007-01-01

    It has been suggested that chiral symmetry is approximately restored in excited hadrons at zero temperature and density (effective symmetry restoration). Using very general chiral symmetry arguments, it is shown that those excited nucleons that are assumed from the spectroscopic patterns to be in approximate chiral multiplets must only weakly decay into the Nπ channel (f N*Nπ /f NNπ ) 2 NNπ . It turns out that for all those well-established excited nucleons which can be classified into chiral doublets the ratio is (f N*Nπ /f NNπ ) 2 ∼0.1 or much smaller for the high-spin states. In contrast, the only well-established excited nucleon for which the chiral partner cannot be identified from the spectroscopic data, N(1520), has a decay constant into the Nπ channel that is comparable with f NNπ

  7. Covariant, chirally symmetric, confining model of mesons

    International Nuclear Information System (INIS)

    Gross, F.; Milana, J.

    1991-01-01

    We introduce a new model of mesons as quark-antiquark bound states. The model is covariant, confining, and chirally symmetric. Our equations give an analytic solution for a zero-mass pseudoscalar bound state in the case of exact chiral symmetry, and also reduce to the familiar, highly successful nonrelativistic linear potential models in the limit of heavy-quark mass and lightly bound systems. In this fashion we are constructing a unified description of all the mesons from the π through the Υ. Numerical solutions for other cases are also presented

  8. Disoriented chiral condensate: Theory and phenomenology

    International Nuclear Information System (INIS)

    Bjorken, J.D.

    1997-12-01

    These notes are an abbreviated version of lectures given at the 1997 Zakopane School. They contain two topics. The first is a description in elementary terms of the basic ideas underlying the speculative hypothesis that pieces of strong-interaction vacuum with a rotated chiral order parameter, disoriented chiral condensate or DCC, might be produced in high energy elementary particle collisions. The second topic is a discussion of the phenomenological techniques which may be applied to data in order to experimentally search for the existence of DCC

  9. Chiral forces and molecular dissymmetry

    International Nuclear Information System (INIS)

    Mohan, R.

    1992-01-01

    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

  10. Highly selective sulfur ylide mediated asymmetric epoxidations and aziridinations using an inexpensive chiral sulfide and applications to the synthesis of quinine and quinidine (abstract)

    International Nuclear Information System (INIS)

    Arshad, M.; Illa, O.; Mcgarrigle, E.M.

    2011-01-01

    Asymmetric sulfur ylide mediated epoxidation, which is considered a complimentary method to asymmetric epoxidation of alkene has been utilized as a key step in the asymmetric total synthesis of complex cinchona alkaloids quinine and quinidine. Isothiocineole 1, which was readily available in one step from very inexpensive starting materials, is employed as a chiral sulfide to prepare the desired sulfonium salt 2. The semi-stabilised ylide derived from this salt on epoxidation with meroquinene aldehyde 3, afforded the required epoxide 4 in 81% yield and 89:11 diastereoselectivity (trans/cis). The epoxide was converted to the target quinine 5 in 73% yield over four steps in one pot. Similarly, the opposite enantiomer of isothiocineole was used to synthesise the corresponding sulfonium salt, which on reaction with meroquinene aldehyde gave epoxide in 73% yield and 84:16 diastereoselectivity (trans/cis). This epoxide was transformed to the target quinidine in 78% yield over four steps in one pot. The epoxidation reactions proceeded under reagent control with high trans selectivity. The effect of sulfide and ylide substituents on the stereochemical outcome of the epoxidation reaction is also prescribed. (author)

  11. Insight into the chiral induction in supramolecular stacks through preferential chiral salvation

    NARCIS (Netherlands)

    George, S.J.; Tomovic, Z.; Schenning, A.P.H.J.; Meijer, E.W.

    2011-01-01

    Preferred handedness in the supramolecular chirality of self-assembled achiral oligo(p-phenylenevinylene) (OPV) derivatives is induced by chiral solvents and spectroscopic probing provides insight into the mechanistic aspects of this chiral induction through chiral solvation

  12. Simultaneous analysis of D-alanine, D-aspartic acid, and D-serine using chiral high-performance liquid chromatography-tandem mass spectrometry and its application to the rat plasma and tissues.

    Science.gov (United States)

    Karakawa, Sachise; Shimbo, Kazutaka; Yamada, Naoyuki; Mizukoshi, Toshimi; Miyano, Hiroshi; Mita, Masashi; Lindner, Wolfgang; Hamase, Kenji

    2015-11-10

    A highly sensitive and selective chiral LC-MS/MS method for D-alanine, D-aspartic acid and D-serine has been developed using the precolumn derivatization reagents, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ-Tag) or p-N,N,N-trimethylammonioanilyl N'-hydroxysuccinimidyl carbamate iodide (TAHS). The thus N-tagged enantiomers of the derivatized amino acids were nicely separated within 20min using the cinchona alkaloid-based zwittterionic ion-exchange type enantioselective column, Chiralpak ZWIX(+). The selected reaction monitoring was applied for detecting the target d-amino acids in biological matrices. By using the present chiral LC-MS/MS method, the three d-amino acids and their l-forms could be simultaneously determined in the range of 0.1-500nmol/mL. Finally, the technique was successfully applied to rat plasma and tissue samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Asymmetric allylation of α-ketoester-derived N-benzoylhydrazones promoted by chiral sulfoxides/N-oxides Lewis bases: highly enantioselective synthesis of quaternary α-substituted α-allyl-α-amino acids.

    Science.gov (United States)

    Reyes-Rangel, Gloria; Bandala, Yamir; García-Flores, Fred; Juaristi, Eusebio

    2013-09-01

    Chiral sulfoxides/N-oxides (R)-1 and (R,R)-2 are effective chiral promoters in the enantioselective allylation of α-keto ester N-benzoylhydrazone derivatives 3a-g to generate the corresponding N-benzoylhydrazine derivatives 4a-g, with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a-b were subsequently treated with SmI2, and the resulting amino esters 5a-b with LiOH to obtain quaternary α-substituted α-allyl α-amino acids 6a-b, whose absolute configuration was assigned as (S), with fundament on chemical correlation and electronic circular dichroism (ECD) data. © 2013 Wiley Periodicals, Inc.

  14. Transport properties of chiral fermions

    Energy Technology Data Exchange (ETDEWEB)

    Puhr, Matthias

    2017-04-26

    of the lattice. For reasonably large lattices it is not feasible to compute the matrix sign function exactly and one has to resort to approximation methods. To compute conserved currents for the overlap operator it is necessary to take derivatives of the overlap operator with respect to the U(1) lattice gauge field. Depending on which approximation is used to evaluate the overlap operator it is not always clear how to compute this derivative. We develop and implement a new numerical method to take derivatives of matrix functions. This method makes it possible to calculate the conserved currents of the finite-density overlap operator with high precision and opens the way to explore anomalous transport phenomena on the lattice. We study the CSE in the confining and deconfining phase of QCD. On very small lattices we observe corrections to the CSE in the phase with broken chiral symmetry, which seem to be of topological origin. For larger lattices we find that in both phases the CSE current is the same as for free fermions.

  15. Detecting the chirality for coupled quantum dots

    International Nuclear Information System (INIS)

    Cao Huijuan; Hu Lian

    2008-01-01

    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

  16. Chirality of magneto-electrodeposited metal film electrodes

    International Nuclear Information System (INIS)

    Mogi, Iwao; Watanabe, Kazuo

    2008-01-01

    The chiral electrode behaviors of magneto-electrodeposited (MED) Ag and Cu films were examined for the electrochemical reactions of D-glucose, L-glucose and L-cysteine. The Ag and Cu films were electrodeposited under a magnetic field of 2 T parallel (+2 T) or antiparallel (-2 T) to the faradaic current. For MED films of both Ag and Cu, the oxidation current of L-glucose was larger than that of D-glucose on the +2 T-film electrodes, and the results were opposite on the - 2 T-film electrodes. These facts demonstrate that the MED metal films possess the ability of chiral recognition for D- and L-glucoses. The MED Ag film electrodes also exhibited chiral behavior for the oxidation of L-cysteine

  17. SU(3) chiral symmetry for baryons

    International Nuclear Information System (INIS)

    Dmitrasinovic, V.

    2011-01-01

    Three-quark nucleon interpolating fields in QCD have well-defined SU L (3)xSU R (3) and U A (1) chiral transformation properties, viz. [(6,3)+(3,6)], [(3,3-bar)+(3-bar,3)], [(8,1)+(1,8)] and their 'mirror' images. It has been shown (phenomenologically) in Ref. [2] that mixing of the [(6,3)+(3,6)] chiral multiplet with one ordinary ('naive') and one 'mirror' field belonging to the [(3,3-bar)+(3-bar,3)], [(8,1)+(1,8)] multiplets can be used to fit the values of the isovector (g A (3) ) and the flavor-singlet (isoscalar) axial coupling (g A (0) ) of the nucleon and then predict the axial F and D coefficients, or vice versa, in reasonable agreement with experiment. In an attempt to derive such mixing from an effective Lagrangian, we construct all SU L (3)xSU R (3) chirally invariant non-derivative one-meson-baryon interactions and then calculate the mixing angles in terms of baryons' masses. It turns out that there are (strong) selection rules: for example, there is only one non-derivative chirally symmetric interaction between J 1/2 fields belonging to the [(6,3)+(3,6)] and the [(3,3-bar)+(3-bar,3)] chiral multiplets, that is also U A (1) symmetric. We also study the chiral interactions of the [(3,3-bar)+(3-bar,3)] and [(8,1)+(1,8)] nucleon fields. Again, there are selection rules that allow only one off-diagonal non-derivative chiral SU L (3)xSU R (3) interaction of this type, that also explicitly breaks the U A (1) symmetry. We use this interaction to calculate the corresponding mixing angles in terms of baryon masses and fit two lowest lying observed nucleon (resonance) masses, thus predicting the third (J = 1/2, I = 3/2)Δ resonance, as well as one or two flavor-singlet Λ hyperon(s), depending on the type of mixing. The effective chiral Lagrangians derived here may be applied to high density matter calculations.

  18. Antibody Binding Selectivity: Alternative Sets of Antigen Residues Entail High-Affinity Recognition.

    Directory of Open Access Journals (Sweden)

    Yves Nominé

    Full Text Available Understanding the relationship between protein sequence and molecular recognition selectivity remains a major challenge. The antibody fragment scFv1F4 recognizes with sub nM affinity a decapeptide (sequence 6TAMFQDPQER15 derived from the N-terminal end of human papilloma virus E6 oncoprotein. Using this decapeptide as antigen, we had previously shown that only the wild type amino-acid or conservative replacements were allowed at positions 9 to 12 and 15 of the peptide, indicating a strong binding selectivity. Nevertheless phenylalanine (F was equally well tolerated as the wild type glutamine (Q at position 13, while all other amino acids led to weaker scFv binding. The interfaces of complexes involving either Q or F are expected to diverge, due to the different physico-chemistry of these residues. This would imply that high-affinity binding can be achieved through distinct interfacial geometries. In order to investigate this point, we disrupted the scFv-peptide interface by modifying one or several peptide positions. We then analyzed the effect on binding of amino acid changes at the remaining positions, an altered susceptibility being indicative of an altered role in complex formation. The 23 starting variants analyzed contained replacements whose effects on scFv1F4 binding ranged from minor to drastic. A permutation analysis (effect of replacing each peptide position by all other amino acids except cysteine was carried out on the 23 variants using the PEPperCHIP® Platform technology. A comparison of their permutation patterns with that of the wild type peptide indicated that starting replacements at position 11, 12 or 13 modified the tolerance to amino-acid changes at the other two positions. The interdependence between the three positions was confirmed by SPR (Biacore® technology. Our data demonstrate that binding selectivity does not preclude the existence of alternative high-affinity recognition modes.

  19. Standard object recognition memory and "what" and "where" components: Improvement by post-training epinephrine in highly habituated rats.

    Science.gov (United States)

    Jurado-Berbel, Patricia; Costa-Miserachs, David; Torras-Garcia, Meritxell; Coll-Andreu, Margalida; Portell-Cortés, Isabel

    2010-02-11

    The present work examined whether post-training systemic epinephrine (EPI) is able to modulate short-term (3h) and long-term (24 h and 48 h) memory of standard object recognition, as well as long-term (24 h) memory of separate "what" (object identity) and "where" (object location) components of object recognition. Although object recognition training is associated to low arousal levels, all the animals received habituation to the training box in order to further reduce emotional arousal. Post-training EPI improved long-term (24 h and 48 h), but not short-term (3 h), memory in the standard object recognition task, as well as 24 h memory for both object identity and object location. These data indicate that post-training epinephrine: (1) facilitates long-term memory for standard object recognition; (2) exerts separate facilitatory effects on "what" (object identity) and "where" (object location) components of object recognition; and (3) is capable of improving memory for a low arousing task even in highly habituated rats.

  20. Integration of open metal sites and Lewis basic sites for construction of a Cu MOF with rare chiral Oh type of cage for high performance of methane purification

    KAUST Repository

    Shi, Zhan; Meng, Lingkun; Niu, Ziyuan; Liang, Chen; Dong, Xinglong; Liu, Kang; Li, Guanghua; Li, Chunguang; Han, Yu; Feng, Shouhua

    2018-01-01

    A Cu MOF [Cu4(PMTD)2(H2O)3]·20H2O, 1, (Where PMTD is (1,4-phenylenebis(5-methyl-4H-1,2,4-triazole-3,4-diyl)bis(5-carboxylato-3,1-phenylene)bis(hydroperoxymethanide) with rare chiral Oh type of cage and dual functionalities of open metal sites and Lewis basic sites based on a designed U-shaped ligand was synthesized by hydrothermal method. It exhibits high-capacity of CO2, C2 and C3 hydrocarbon storage capacity under atmospheric pressure as well as high H2 (1.96% wt) adsorption capacity at 77K. Methane purification capacity was tested and verified step by step. Isosteric heats (Qst) study reveals that CH4 has the weakest van der Waals host- guest interactions among the seven gases at 298K. Ideal adsorbed solution theory (IAST) calculation reveals that compound 1 is more selective toward CO2, C2H6 and C3H8 over CH4 in further calculating its separation capacity, as exemplified for CO2/CH4 (50:50, 5:95), C2H6/CH4 (50:50, 5:95) or C3H8/CH4 (50:50, 5:95) binary gas mixtures. Breakthrough experiments show that 1 has a significantly higher adsorption capacity for CO2, C2H6 and C3H8 than CH4. The selective adsorption properties of 1 make it a promising candidate for methane purification.

  1. Integration of open metal sites and Lewis basic sites for construction of a Cu MOF with rare chiral Oh type of cage for high performance of methane purification

    KAUST Repository

    Shi, Zhan

    2018-01-18

    A Cu MOF [Cu4(PMTD)2(H2O)3]·20H2O, 1, (Where PMTD is (1,4-phenylenebis(5-methyl-4H-1,2,4-triazole-3,4-diyl)bis(5-carboxylato-3,1-phenylene)bis(hydroperoxymethanide) with rare chiral Oh type of cage and dual functionalities of open metal sites and Lewis basic sites based on a designed U-shaped ligand was synthesized by hydrothermal method. It exhibits high-capacity of CO2, C2 and C3 hydrocarbon storage capacity under atmospheric pressure as well as high H2 (1.96% wt) adsorption capacity at 77K. Methane purification capacity was tested and verified step by step. Isosteric heats (Qst) study reveals that CH4 has the weakest van der Waals host- guest interactions among the seven gases at 298K. Ideal adsorbed solution theory (IAST) calculation reveals that compound 1 is more selective toward CO2, C2H6 and C3H8 over CH4 in further calculating its separation capacity, as exemplified for CO2/CH4 (50:50, 5:95), C2H6/CH4 (50:50, 5:95) or C3H8/CH4 (50:50, 5:95) binary gas mixtures. Breakthrough experiments show that 1 has a significantly higher adsorption capacity for CO2, C2H6 and C3H8 than CH4. The selective adsorption properties of 1 make it a promising candidate for methane purification.

  2. Novel chiral core-shell silica microspheres with trans-(1R,2R)-diaminocyclohexane bridged in the mesoporous shell: synthesis, characterization and application in high performance liquid chromatography.

    Science.gov (United States)

    Wu, Xiabing; You, Linjun; Di, Bin; Hao, Weiqiang; Su, Mengxiang; Gu, Yu; Shen, Lingling

    2013-07-19

    Novel chiral core-shell silica microspheres with trans-(1R,2R)-diaminocyclohexane (DACH) moiety bridged in the mesoporous shell were synthesized using layer-by-layer method. The chiral mesoporous shell around the nonporous silica core was formed by the co-condensation of N,N'-bis-[(triethoxysilyl)propyl]-trans-(1R,2R)-bis-(ureido)-cyclohexane (DACH-BS) and tetraethoxysilane (TEOS) using octadecyltrimethylammonium chloride (C18TMACl) and triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (P123) as the templates. The functionalized core-shell silica microspheres were characterized and tested as chiral stationary phases for high performance liquid chromatography (HPLC). R/S-1,1'-bi-2,2'-naphthol, R/S-6,6'-dibromo-1,1'-bi-2-naphthol and R/S-1,1'-bi-2,2'-phenanthrol were enantioseparated rapidly on the column packed with the DACH core-shell silica particles. Moreover, the column packed with core-shell particles exhibited better performance than the column packed with the DACH functionalized periodic mesoporous organosilicas. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Non-uniform chiral phase in effective chiral quark models

    International Nuclear Information System (INIS)

    Sadzikowski, M.; Broniowski, W.

    2000-01-01

    We analyze the phase diagram in effective chiral quark models (the Nambu-Jona-Lasinio model, the σ-model with quarks) and show that at the mean-field level a phase with a periodically-modulated chiral fields separates the usual phases with broken and restored chiral symmetry. A possible signal of such a phase is the production of multipion jets travelling in opposite directions, with individual pions having momenta of the order of several hundred MeV. This signal can be interpreted in terms of disoriented chiral condensates. (author)

  4. Synthesis of novel nanostructured chiral poly(amide-imide)s ...

    Indian Academy of Sciences (India)

    aOrganic Polymer Chemistry Research Laboratory, Department of Chemistry,. bNanotechnology and ..... environmental pollution due to solvent loss. The use of ..... als, processable high-performance engineering plastics, constructing chiral ...

  5. Chiral magnetic effect of light

    Science.gov (United States)

    Hayata, Tomoya

    2018-05-01

    We study a photonic analog of the chiral magnetic (vortical) effect. We discuss that the vector component of magnetoelectric tensors plays a role of "vector potential," and its rotation is understood as "magnetic field" of a light. Using the geometrical optics approximation, we show that "magnetic fields" cause an anomalous shift of a wave packet of a light through an interplay with the Berry curvature of photons. The mechanism is the same as that of the chiral magnetic (vortical) effect of a chiral fermion, so that we term the anomalous shift "chiral magnetic effect of a light." We further study the chiral magnetic effect of a light beyond geometric optics by directly solving the transmission problem of a wave packet at a surface of a magnetoelectric material. We show that the experimental signal of the chiral magnetic effect of a light is the nonvanishing of transverse displacements for the beam normally incident to a magnetoelectric material.

  6. Automated, high accuracy classification of Parkinsonian disorders: a pattern recognition approach.

    Directory of Open Access Journals (Sweden)

    Andre F Marquand

    Full Text Available Progressive supranuclear palsy (PSP, multiple system atrophy (MSA and idiopathic Parkinson's disease (IPD can be clinically indistinguishable, especially in the early stages, despite distinct patterns of molecular pathology. Structural neuroimaging holds promise for providing objective biomarkers for discriminating these diseases at the single subject level but all studies to date have reported incomplete separation of disease groups. In this study, we employed multi-class pattern recognition to assess the value of anatomical patterns derived from a widely available structural neuroimaging sequence for automated classification of these disorders. To achieve this, 17 patients with PSP, 14 with IPD and 19 with MSA were scanned using structural MRI along with 19 healthy controls (HCs. An advanced probabilistic pattern recognition approach was employed to evaluate the diagnostic value of several pre-defined anatomical patterns for discriminating the disorders, including: (i a subcortical motor network; (ii each of its component regions and (iii the whole brain. All disease groups could be discriminated simultaneously with high accuracy using the subcortical motor network. The region providing the most accurate predictions overall was the midbrain/brainstem, which discriminated all disease groups from one another and from HCs. The subcortical network also produced more accurate predictions than the whole brain and all of its constituent regions. PSP was accurately predicted from the midbrain/brainstem, cerebellum and all basal ganglia compartments; MSA from the midbrain/brainstem and cerebellum and IPD from the midbrain/brainstem only. This study demonstrates that automated analysis of structural MRI can accurately predict diagnosis in individual patients with Parkinsonian disorders, and identifies distinct patterns of regional atrophy particularly useful for this process.

  7. Bulky melamine-based Zn-porphyrin tweezer as a CD probe of molecular chirality.

    Science.gov (United States)

    Petrovic, Ana G; Vantomme, Ghislaine; Negrón-Abril, Yashira L; Lubian, Elisa; Saielli, Giacomo; Menegazzo, Ileana; Cordero, Roselynn; Proni, Gloria; Nakanishi, Koji; Carofiglio, Tommaso; Berova, Nina

    2011-10-01

    The transfer of chirality from a guest molecule to an achiral host is the subject of significant interest especially when, upon chiral induction, the chiroptical response of the host/guest complex can effectively report the absolute configuration (AC) of the guest. For more than a decade, dimeric metalloporphyrin hosts (tweezers) have been successfully applied as chirality probes for determination of the AC for a wide variety of chiral synthetic compounds and natural products. The objective of this study is to investigate the utility of a new class of melamine-bridged Zn-porphyrin tweezers as sensitive AC reporters. A combined approach based on an experimental CD analysis and a theoretical prediction of the prevailing interporphyrin helicity demonstrates that these tweezers display favorable properties for chiral recognition. Herein, we discuss the application of the melamine-bridged tweezer to the chiral recognition of a diverse set of chiral guests, such as 1,2-diamines, α-amino-esters and amides, secondary alcohols, and 1,2-amino-alcohols. The bulky periphery and the presence of a rigid porphyrin linkage lead, in some cases, to a more enhanced CD sensitivity than that reported earlier with other tweezers. Copyright © 2011 Wiley-Liss, Inc.

  8. Chiral colour and axigluons

    International Nuclear Information System (INIS)

    Cuypers, F.

    1989-01-01

    The authors studies the phenomenological implications of the Chiral Colour model which allow him to derive experimental bounds on the axigluon mass or to predict deviations from the Standard Model. After a short introduction to the theory, the author examines the way it modifies the standard decay of quarkonium. Comparison with the observed lifetime of the upsilon allows him to exclude the existence of axigluons lighter than 9 GeV. (Others have since extended the work and were able to increase this limit to 25 GeV.) He then studies the Chiral Colour contribution to the hadronic cross-section in the electron-positron scattering and derive a conservative lower bound of 50 GeV for the axigluon mass. Finally, he predicts observable enhancements of the lifetime and rare decay channels of the Z O in the presence of light axigluons

  9. Spontaneous chiral symmetry breaking in early molecular networks

    Directory of Open Access Journals (Sweden)

    Markovitch Omer

    2010-05-01

    Full Text Available Abstract Background An important facet of early biological evolution is the selection of chiral enantiomers for molecules such as amino acids and sugars. The origin of this symmetry breaking is a long-standing question in molecular evolution. Previous models addressing this question include particular kinetic properties such as autocatalysis or negative cross catalysis. Results We propose here a more general kinetic formalism for early enantioselection, based on our previously described Graded Autocatalysis Replication Domain (GARD model for prebiotic evolution in molecular assemblies. This model is adapted here to the case of chiral molecules by applying symmetry constraints to mutual molecular recognition within the assembly. The ensuing dynamics shows spontaneous chiral symmetry breaking, with transitions towards stationary compositional states (composomes enriched with one of the two enantiomers for some of the constituent molecule types. Furthermore, one or the other of the two antipodal compositional states of the assembly also shows time-dependent selection. Conclusion It follows that chiral selection may be an emergent consequence of early catalytic molecular networks rather than a prerequisite for the initiation of primeval life processes. Elaborations of this model could help explain the prevalent chiral homogeneity in present-day living cells. Reviewers This article was reviewed by Boris Rubinstein (nominated by Arcady Mushegian, Arcady Mushegian, Meir Lahav (nominated by Yitzhak Pilpel and Sergei Maslov.

  10. Chiral Biomarkers in Meteorites

    Science.gov (United States)

    Hoover, Richard B.

    2010-01-01

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

  11. On chiral bosonization

    International Nuclear Information System (INIS)

    Bastianelli, F.

    1991-01-01

    We examine the bosonization of chiral fermions in a gravitational background, using a path integral approach. The bosonic model is given by an action proposed some time ago by Floreanini and Jackiw, suitably coupled to gravity. We use a regulator for the path integral measure obtained from the general construction of Diaz, Hatsuda, Troost, van Nieuwenhuizen and Van Proeyen. We show that the effective actions are identical. (orig.)

  12. Dynamical chiral bag model

    International Nuclear Information System (INIS)

    Colanero, K.; Chu, M.-C.

    2002-01-01

    We study a dynamical chiral bag model, in which massless fermions are confined within an impenetrable but movable bag coupled to meson fields. The self-consistent motion of the bag is obtained by solving the equations of motion exactly assuming spherical symmetry. When the bag interacts with an external meson wave we find three different kinds of resonances: fermionic, geometric, and σ resonances. We discuss the phenomenological implications of our results

  13. 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

  14. Chiral gold nanowires with boerdijk-coxeter-bernal structure

    KAUST Repository

    Zhu, Yihan

    2014-09-10

    A Boerdijk-Coxeter-Bernal (BCB) helix is made of linearly stacked regular tetrahedra (tetrahelix). As such, it is chiral without nontrivial translational or rotational symmetries. We demonstrate here an example of the chiral BCB structure made of totally symmetrical gold atoms, created in nanowires by direct chemical synthesis. Detailed study by high-resolution electron microscopy illustrates their elegant chiral structure and the unique one-dimensional "pseudo-periodicity". The BCB-type atomic packing mode is proposed to be a result of the competition and compromise between the lattice and surface energy.

  15. Brain dynamics of upstream perceptual processes leading to visual object recognition: a high density ERP topographic mapping study.

    Science.gov (United States)

    Schettino, Antonio; Loeys, Tom; Delplanque, Sylvain; Pourtois, Gilles

    2011-04-01

    Recent studies suggest that visual object recognition is a proactive process through which perceptual evidence accumulates over time before a decision can be made about the object. However, the exact electrophysiological correlates and time-course of this complex process remain unclear. In addition, the potential influence of emotion on this process has not been investigated yet. We recorded high density EEG in healthy adult participants performing a novel perceptual recognition task. For each trial, an initial blurred visual scene was first shown, before the actual content of the stimulus was gradually revealed by progressively adding diagnostic high spatial frequency information. Participants were asked to stop this stimulus sequence as soon as they could correctly perform an animacy judgment task. Behavioral results showed that participants reliably gathered perceptual evidence before recognition. Furthermore, prolonged exploration times were observed for pleasant, relative to either neutral or unpleasant scenes. ERP results showed distinct effects starting at 280 ms post-stimulus onset in distant brain regions during stimulus processing, mainly characterized by: (i) a monotonic accumulation of evidence, involving regions of the posterior cingulate cortex/parahippocampal gyrus, and (ii) true categorical recognition effects in medial frontal regions, including the dorsal anterior cingulate cortex. These findings provide evidence for the early involvement, following stimulus onset, of non-overlapping brain networks during proactive processes eventually leading to visual object recognition. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Identifying chiral bands in real nuclei

    International Nuclear Information System (INIS)

    Shirinda, O.; Lawrie, E.A.

    2012-01-01

    The application of the presently used fingerprints of chiral bands (originally derived for strongly broken chirality) is investigated for real chiral systems. In particular the chiral fingerprints concerning the B(M1) staggering patterns and the energy staggering are studied. It is found that both fingerprints show considerable changes for real chiral systems, a behaviour that creates a significant risk for misinterpretation of the experimental data and can lead to a failure to identify real chiral systems. (orig.)

  17. Chiral algebras of class S

    CERN Document Server

    Beem, Christopher; Rastelli, Leonardo; van Rees, Balt C.

    2015-01-01

    Four-dimensional N=2 superconformal field theories have families of protected correlation functions that possess the structure of two-dimensional chiral algebras. In this paper, we explore the chiral algebras that arise in this manner in the context of theories of class S. The class S duality web implies nontrivial associativity properties for the corresponding chiral algebras, the structure of which is best summarized in the language of generalized topological quantum field theory. We make a number of conjectures regarding the chiral algebras associated to various strongly coupled fixed points.

  18. Self-recognition of high-mannose type glycans mediating adhesion of embryonal fibroblasts.

    Science.gov (United States)

    Yoon, Seon-Joo; Utkina, Natalia; Sadilek, Martin; Yagi, Hirokazu; Kato, Koichi; Hakomori, Sen-itiroh

    2013-07-01

    High-mannose type N-linked glycan with 6 mannosyl residues, termed "M6Gn2", displayed clear binding to the same M6Gn2, conjugated with ceramide mimetic (cer-m) and incorporated in liposome, or coated on polystyrene plates. However, the conjugate of M6Gn2-cer-m did not interact with complex-type N-linked glycan with various structures having multiple GlcNAc termini, conjugated with cer-m. The following observations indicate that hamster embryonic fibroblast NIL-2 K cells display homotypic autoadhesion, mediated through the self-recognition capability of high-mannose type glycans expressed on these cells: (i) NIL-2 K cells display clear binding to lectins capable of binding to high-mannose type glycans (e.g., ConA), but not to other lectins capable of binding to other carbohydrates (e.g. GS-II). (ii) NIL-2 K cells adhere strongly to plates coated with M6Gn2-cer-m, but not to plates coated with complex-type N-linked glycans having multiple GlcNAc termini, conjugated with cer-m; (iii) degree of NIL-2 K cell adhesion to plates coated with M6Gn2-cer-m showed a clear dose-dependence on the amount of M6Gn2-cer-m; and (iv) the degree of NIL-2 K adhesion to plates coated with M6Gn2-cer-m was inhibited in a dose-dependent manner by α1,4-L-mannonolactone, the specific inhibitor in high-mannose type glycans addition. These data indicate that adhesion of NIL-2 K is mediated by self-aggregation of high mannose type glycan. Further studies are to be addressed on auto-adhesion of other types of cells based on self interaction of high mannose type glycans.

  19. Emotion recognition deficits as predictors of transition in individuals at clinical high risk for schizophrenia: a neurodevelopmental perspective.

    Science.gov (United States)

    Corcoran, C M; Keilp, J G; Kayser, J; Klim, C; Butler, P D; Bruder, G E; Gur, R C; Javitt, D C

    2015-10-01

    Schizophrenia is characterized by profound and disabling deficits in the ability to recognize emotion in facial expression and tone of voice. Although these deficits are well documented in established schizophrenia using recently validated tasks, their predictive utility in at-risk populations has not been formally evaluated. The Penn Emotion Recognition and Discrimination tasks, and recently developed measures of auditory emotion recognition, were administered to 49 clinical high-risk subjects prospectively followed for 2 years for schizophrenia outcome, and 31 healthy controls, and a developmental cohort of 43 individuals aged 7-26 years. Deficit in emotion recognition in at-risk subjects was compared with deficit in established schizophrenia, and with normal neurocognitive growth curves from childhood to early adulthood. Deficits in emotion recognition significantly distinguished at-risk patients who transitioned to schizophrenia. By contrast, more general neurocognitive measures, such as attention vigilance or processing speed, were non-predictive. The best classification model for schizophrenia onset included both face emotion processing and negative symptoms, with accuracy of 96%, and area under the receiver-operating characteristic curve of 0.99. In a parallel developmental study, emotion recognition abilities were found to reach maturity prior to traditional age of risk for schizophrenia, suggesting they may serve as objective markers of early developmental insult. Profound deficits in emotion recognition exist in at-risk patients prior to schizophrenia onset. They may serve as an index of early developmental insult, and represent an effective target for early identification and remediation. Future studies investigating emotion recognition deficits at both mechanistic and predictive levels are strongly encouraged.

  20. Enantioseparation of angiotensin II receptor type 1 blockers: evaluation of 6-substituted carbamoyl benzimidazoles on immobilized polysaccharide-based chiral stationary phases. Unusual temperature behavior.

    Science.gov (United States)

    Su, Ran; Hou, Zhun; Sang, Lihong; Zhou, Zhi-Ming; Fang, Hao; Yang, Xinying

    2017-09-15

    Enantioseparation of thirteen 6-substituted carbamoyl benzimidazoles by high-performance liquid chromatography (HPLC) was investigated using two immobilized polysaccharide-based chiral stationary phases (CSPs), Chiralpak IC and Chiralpak IA, in normal-phase mode. Most of the examined compounds were completely resolved. The effects of a polar alcohol modifier, analyte structure, and column temperature on the chiral recognition were investigated. Furthermore, the structure-retention relationship was evaluated, and thermodynamic parameters were calculated from plots of ln k' or ln α versus 1/T. The thermodynamic parameters indicated that the separations were enthalpy-driven. Moreover, nonlinear van't Hoff plots were obtained on Chiralpak IA. However, two unusual phenomena were observed: (1) an unusual increase in retention with increasing temperature with linear van't Hoff plots on Chiralpak IC and (2) an extremely high T iso value (i.e., several thousand degrees centigrade). Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Critical constraints on chiral hierarchies

    International Nuclear Information System (INIS)

    Chivukula, R.S.; Golden, M.; Simmons, E.H.

    1993-01-01

    Critical dynamics constrains models of dynamical electroweak symmetry breaking in which the scale of high-energy physics is far above 1 TeV. A big hierarchy requires the high-energy theory to have a second-order chiral phase transition, near which the theory is described by a low-energy effective Lagrangian with composite ''Higgs'' scalars. As scalar theories with more than one Φ 4 coupling can have a Coleman-Weinberg instability and a first-order transition, such dynamical EWSB models cannot always support a large hierarchy. If the large-N c Nambu--Jona-Lasinio model is a good approximation to the top-condensate and strong extended technicolor models, they will not produce acceptable EWSB

  2. Rationalization of chirality induction and inversion in a zinc trisporphyrinate by a chiral monoalcohol.

    Science.gov (United States)

    Li, Li; Hu, Chuanjiang; Shi, Bo; Wang, Yong

    2016-05-10

    A new host-guest system is formed between a benzene tricarboxamide linked zinc trisporphyrinate and a chiral monoalcohol (1-phenylethylalcohol). CD spectra show the chirality induction and inversion processes, which are controlled by the corresponding 1 : 1 and 1 : 2 coordination complexes. The binding constants calculated by UV-vis and CD spectral data are much larger than that for [Zn(TPP)] (TPP = tetraphenylporphyrin). The crystallographic structure of the host-guest complex reveals that multiple intramolecular hydrogen bonds and π-π interactions could contribute to its high binding affinity to 1-phenylethylalcohol. The DFT calculations suggest that the spatial orientations of porphyrin moieties change from the 1 : 1 complex to the 1 : 2 complex. The chirality induction and inversion processes are rationalized by the summation of pairwise interactions among multichromophores according to pairwise additivity.

  3. High-Speed Video System for Micro-Expression Detection and Recognition

    Directory of Open Access Journals (Sweden)

    Diana Borza

    2017-12-01

    Full Text Available Micro-expressions play an essential part in understanding non-verbal communication and deceit detection. They are involuntary, brief facial movements that are shown when a person is trying to conceal something. Automatic analysis of micro-expression is challenging due to their low amplitude and to their short duration (they occur as fast as 1/15 to 1/25 of a second. We propose a fully micro-expression analysis system consisting of a high-speed image acquisition setup and a software framework which can detect the frames when the micro-expressions occurred as well as determine the type of the emerged expression. The detection and classification methods use fast and simple motion descriptors based on absolute image differences. The recognition module it only involves the computation of several 2D Gaussian probabilities. The software framework was tested on two publicly available high speed micro-expression databases and the whole system was used to acquire new data. The experiments we performed show that our solution outperforms state of the art works which use more complex and computationally intensive descriptors.

  4. Simplified chiral superfield propagators for chiral constant mass superfields

    International Nuclear Information System (INIS)

    Srivastava, P.P.

    1983-01-01

    Unconstrained superfield potentials are introduced to derive Feynman rules for chiral superfields following conventional procedure which is easy and instructive. Propagators for the case when the mass parameters are constant chiral superfields are derived. The propagators reported here are very simple compared to those available in literature and allow a manageable calculation of higher loops. (Author) [pt

  5. A Violation of the Conditional Independence Assumption in the Two-High-Threshold Model of Recognition Memory

    Science.gov (United States)

    Chen, Tina; Starns, Jeffrey J.; Rotello, Caren M.

    2015-01-01

    The 2-high-threshold (2HT) model of recognition memory assumes that test items result in distinct internal states: they are either detected or not, and the probability of responding at a particular confidence level that an item is "old" or "new" depends on the state-response mapping parameters. The mapping parameters are…

  6. Chiral nanophotonics chiral optical properties of plasmonic systems

    CERN Document Server

    Schäferling, Martin

    2017-01-01

    This book describes the physics behind the optical properties of plasmonic nanostructures focusing on chiral aspects. It explains in detail how the geometry determines chiral near-fields and how to tailor their shape and strength. Electromagnetic fields with strong optical chirality interact strongly with chiral molecules and, therefore, can be used for enhancing the sensitivity of chiroptical spectroscopy techniques. Besides a short review of the latest results in the field of plasmonically enhanced enantiomer discrimination, this book introduces the concept of chiral plasmonic near-field sources for enhanced chiroptical spectroscopy. The discussion of the fundamental properties of these light sources provides the theoretical basis for further optimizations and is of interest for researchers at the intersection of nano-optics, plasmonics and stereochemistry. .

  7. Combining high-speed SVM learning with CNN feature encoding for real-time target recognition in high-definition video for ISR missions

    Science.gov (United States)

    Kroll, Christine; von der Werth, Monika; Leuck, Holger; Stahl, Christoph; Schertler, Klaus

    2017-05-01

    For Intelligence, Surveillance, Reconnaissance (ISR) missions of manned and unmanned air systems typical electrooptical payloads provide high-definition video data which has to be exploited with respect to relevant ground targets in real-time by automatic/assisted target recognition software. Airbus Defence and Space is developing required technologies for real-time sensor exploitation since years and has combined the latest advances of Deep Convolutional Neural Networks (CNN) with a proprietary high-speed Support Vector Machine (SVM) learning method into a powerful object recognition system with impressive results on relevant high-definition video scenes compared to conventional target recognition approaches. This paper describes the principal requirements for real-time target recognition in high-definition video for ISR missions and the Airbus approach of combining an invariant feature extraction using pre-trained CNNs and the high-speed training and classification ability of a novel frequency-domain SVM training method. The frequency-domain approach allows for a highly optimized implementation for General Purpose Computation on a Graphics Processing Unit (GPGPU) and also an efficient training of large training samples. The selected CNN which is pre-trained only once on domain-extrinsic data reveals a highly invariant feature extraction. This allows for a significantly reduced adaptation and training of the target recognition method for new target classes and mission scenarios. A comprehensive training and test dataset was defined and prepared using relevant high-definition airborne video sequences. The assessment concept is explained and performance results are given using the established precision-recall diagrams, average precision and runtime figures on representative test data. A comparison to legacy target recognition approaches shows the impressive performance increase by the proposed CNN+SVM machine-learning approach and the capability of real-time high

  8. High-accuracy and robust face recognition system based on optical parallel correlator using a temporal image sequence

    Science.gov (United States)

    Watanabe, Eriko; Ishikawa, Mami; Ohta, Maiko; Kodate, Kashiko

    2005-09-01

    Face recognition is used in a wide range of security systems, such as monitoring credit card use, searching for individuals with street cameras via Internet and maintaining immigration control. There are still many technical subjects under study. For instance, the number of images that can be stored is limited under the current system, and the rate of recognition must be improved to account for photo shots taken at different angles under various conditions. We implemented a fully automatic Fast Face Recognition Optical Correlator (FARCO) system by using a 1000 frame/s optical parallel correlator designed and assembled by us. Operational speed for the 1: N (i.e. matching a pair of images among N, where N refers to the number of images in the database) identification experiment (4000 face images) amounts to less than 1.5 seconds, including the pre/post processing. From trial 1: N identification experiments using FARCO, we acquired low error rates of 2.6% False Reject Rate and 1.3% False Accept Rate. By making the most of the high-speed data-processing capability of this system, much more robustness can be achieved for various recognition conditions when large-category data are registered for a single person. We propose a face recognition algorithm for the FARCO while employing a temporal image sequence of moving images. Applying this algorithm to a natural posture, a two times higher recognition rate scored compared with our conventional system. The system has high potential for future use in a variety of purposes such as search for criminal suspects by use of street and airport video cameras, registration of babies at hospitals or handling of an immeasurable number of images in a database.

  9. Peptide Pattern Recognition for high-throughput protein sequence analysis and clustering

    DEFF Research Database (Denmark)

    Busk, Peter Kamp

    2017-01-01

    Large collections of protein sequences with divergent sequences are tedious to analyze for understanding their phylogenetic or structure-function relation. Peptide Pattern Recognition is an algorithm that was developed to facilitate this task but the previous version does only allow a limited...... number of sequences as input. I implemented Peptide Pattern Recognition as a multithread software designed to handle large numbers of sequences and perform analysis in a reasonable time frame. Benchmarking showed that the new implementation of Peptide Pattern Recognition is twenty times faster than...... the previous implementation on a small protein collection with 673 MAP kinase sequences. In addition, the new implementation could analyze a large protein collection with 48,570 Glycosyl Transferase family 20 sequences without reaching its upper limit on a desktop computer. Peptide Pattern Recognition...

  10. Regioconvergent and Enantioselective Rhodium-Catalyzed Hydroamination of Internal and Terminal Alkynes: A Highly Flexible Access to Chiral Pyrazoles.

    Science.gov (United States)

    Haydl, Alexander M; Hilpert, Lukas J; Breit, Bernhard

    2016-05-04

    The rhodium-catalyzed asymmetric N-selective coupling of pyrazole derivatives with internal and terminal alkynes features an utmost chemo-, regio-, and enantioselective access to enantiopure allylic pyrazoles, readily available for incorporation in small-molecule pharmaceuticals. This methodology is distinguished by a broad substrate scope, resulting in a remarkable compatability with a variety of different functional groups. It furthermore exhibits an intriguing case of regio-, position-, and enantioselectivity in just one step, underscoring the sole synthesis of just one out of up to six possible products in a highly flexible approach to allylated pyrazoles by emanating from various internal and terminal alkynes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Antikaon induced Ξ production from a chiral model at NLO

    Directory of Open Access Journals (Sweden)

    Feijoo A.

    2014-01-01

    Full Text Available We study the meson-baryon interaction in the strangeness S = −1 sector using a chiral unitary approach, paying particular attention to the K̄N → KΞ reaction, especially important for constraining the next-to-leading order chiral terms, and considering also the effect of high spin hyperonic resonances. We also present results for the production of Ξ hyperons in nuclei

  12. Towards Measurements of Chiral Effects Using Identified Particles from STAR

    Czech Academy of Sciences Publication Activity Database

    Wen, Lw.; Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Bielčík, J.; Bielčíková, Jana; Chaloupka, P.; Federič, Pavol; Rusňák, Jan; Rusňáková, O.; Šimko, Miroslav; Šumbera, Michal; Vértési, Robert

    2017-01-01

    Roč. 967, č. 11 (2017), s. 756-759 ISSN 0375-9474 R&D Projects: GA MŠk LG15001; GA MŠk LM2015054 Institutional support: RVO:61389005 Keywords : STAR collaboration * chiral magnetic effect * chiral magnetic wave * gamma correlation * k(K) parameter Subject RIV: BF - Elementary Particles and High Energy Physics OBOR OECD: Particles and field physics Impact factor: 1.916, year: 2016

  13. Lattice regularized chiral perturbation theory

    International Nuclear Information System (INIS)

    Borasoy, Bugra; Lewis, Randy; Ouimet, Pierre-Philippe A.

    2004-01-01

    Chiral perturbation theory can be defined and regularized on a spacetime lattice. A few motivations are discussed here, and an explicit lattice Lagrangian is reviewed. A particular aspect of the connection between lattice chiral perturbation theory and lattice QCD is explored through a study of the Wess-Zumino-Witten term

  14. Two-chiral component microemulsion EKC - chiral surfactant and chiral oil. Part 2: diethyl tartrate.

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-08-01

    In this second study on dual-chirality microemulsions containing a chiral surfactant and a chiral oil, a less hydrophobic and lower interfacial tension chiral oil, diethyl tartrate, is employed (Part 1, Foley, J. P. et al.., Electrophoresis, DOI: 10.1002/elps.200600551). Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2-hexanol (1.65% v/v), and diethyl tartrate (D, L, or racemic, 0.88% v/v) were examined as pseudostationary phases (PSPs) for the enantioseparation of six chiral pharmaceutical compounds: pseudoephedrine, ephedrine, N-methyl ephedrine, metoprolol, synephrine, and atenolol. Average efficiencies increased with the addition of a chiral oil to R-DDCV PSP formulations. Modest improvements in resolution and enantioselectivity (alpha(enant)) were achieved with two-chiral-component systems over the one-chiral-component microemulsion. Slight enantioselective synergies were confirmed using a thermodynamic model. Results obtained in this study are compared to those obtained in Part 1 as well as those obtained with chiral MEEKC using an achiral, low-interfacial-tension oil (ethyl acetate). Dual-chirality microemulsions with the more hydrophobic oil dibutyl tartrate yielded, relative to diethyl tartrate, higher efficiencies (100,000-134,000 vs. 80,800-94,300), but lower resolution (1.64-1.91 vs. 2.08-2.21) due to lower enantioselectivities (1.060-1.067 vs. 1.078-1.081). Atenolol enantiomers could not be separated with the dibutyl tartrate-based microemulsions but were partially resolved using diethyl tartrate microemulsions. A comparable single-chirality microemulsion based on the achiral oil ethyl acetate yielded, relative to diethyl tartrate, lower efficiency (78 300 vs. 91 600), higher resolution (1.99 vs. 1.83), and similar enantioselectivities.

  15. Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization.

    Science.gov (United States)

    Wang, Jin Zhao; Zeng, Su; Hu, Gong Yun; Wang, Dan Hua

    2009-04-10

    SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm x 4.6 mm, 5 microm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.

  16. Flatspace chiral supergravity

    Science.gov (United States)

    Bagchi, Arjun; Basu, Rudranil; Detournary, Stéphane; Parekh, Pulastya

    2018-05-01

    We propose a holographic duality between a 2 dimensional (2d) chiral superconformal field theory and a certain theory of supergravity in 3d with flatspace boundary conditions that is obtained as a double scaling limit of a parity breaking theory of supergravity. We show how the asymptotic symmetries of the bulk theory reduce from the "despotic" super Bondi-Metzner-Sachs algebra (or equivalently the inhomogeneous super Galilean conformal algebra) to a single copy of the super-Virasoro algebra in this limit and also reproduce the same reduction from a study of null vectors in the putative 2d dual field theory.

  17. Factors associated with recognition of the signs of dating violence by Japanese junior high school students.

    Science.gov (United States)

    Nagamatsu, Miyuki; Hamada, Yukiko; Hara, Kenichi

    2016-01-01

    This study investigated factors associated with the ability of Japanese junior high school students to recognize the signs of dating violence. During a period of 20 months (from June 2011 to January 2013), a survey was distributed to 3340 students aged 13-15 years in the second and third grades at 18 junior high schools in a Japanese prefecture. The survey examined gender, recognition of the signs of dating violence, knowledge of dating violence, self-esteem, attitudes toward sexual activity, attitudes toward an equal dating relationship, and relationships with school teachers. Multiple linear regression analyses were performed to identify predictors of the ability of boys and girls respondents to recognize the signs of physical and psychological dating violence. Binary multiple logistic regression analysis was also performed to identify predictors of the ability of boys and girls respondents to recognize the sign of sexual dating violence. The Ethics Committee of Saga University Medical School approved the study protocol. A total of 3050 (91.3%) students participated in this study (1547 boys and 1503 girls). Gender differences were noted with regard to the scores for some of the variables measured. The results indicated that boys who had more knowledge of dating violence, who focused on an equal dating relationship, and had a positive relationship with their teachers showed a greater ability to recognize the signs of dating violence. In addition, boys with a conservative attitude toward sexual activity showed a greater ability to recognize the signs of physical and sexual violence. Furthermore, girls with more knowledge of dating violence had a conservative attitude toward sexual activity, and girls who focused on an equal dating relationship showed greater ability to recognize the signs of dating violence. These findings suggest that education programs to prevent dating violence should promote understanding about dating violence with consideration of gender

  18. Using the automata processor for fast pattern recognition in high energy physics experiments—A proof of concept

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Michael H.L.S., E-mail: mwang@fnal.gov [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Cancelo, Gustavo; Green, Christopher [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Guo, Deyuan; Wang, Ke [University of Virginia, Charlottesville, VA 22904 (United States); Zmuda, Ted [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2016-10-01

    We explore the Micron Automata Processor (AP) as a suitable commodity technology that can address the growing computational needs of pattern recognition in High Energy Physics (HEP) experiments. A toy detector model is developed for which an electron track confirmation trigger based on the Micron AP serves as a test case. Although primarily meant for high speed text-based searches, we demonstrate a proof of concept for the use of the Micron AP in a HEP trigger application.

  19. Nanoscale chirality in metal and semiconductor nanoparticles.

    Science.gov (United States)

    Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

    2016-10-18

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

  20. Chiral quantum optics.

    Science.gov (United States)

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

    2017-01-25

    Advanced photonic nanostructures are currently revolutionizing the optics and photonics that underpin applications ranging from light technology to quantum-information processing. The strong light confinement in these structures can lock the local polarization of the light to its propagation direction, leading to propagation-direction-dependent emission, scattering and absorption of photons by quantum emitters. The possibility of such a propagation-direction-dependent, or chiral, light-matter interaction is not accounted for in standard quantum optics and its recent discovery brought about the research field of chiral quantum optics. The latter offers fundamentally new functionalities and applications: it enables the assembly of non-reciprocal single-photon devices that can be operated in a quantum superposition of two or more of their operational states and the realization of deterministic spin-photon interfaces. Moreover, engineered directional photonic reservoirs could lead to the development of complex quantum networks that, for example, could simulate novel classes of quantum many-body systems.

  1. Recognition memory for low- and high-frequency-filtered emotional faces: Low spatial frequencies drive emotional memory enhancement, whereas high spatial frequencies drive the emotion-induced recognition bias.

    Science.gov (United States)

    Rohr, Michaela; Tröger, Johannes; Michely, Nils; Uhde, Alarith; Wentura, Dirk

    2017-07-01

    This article deals with two well-documented phenomena regarding emotional stimuli: emotional memory enhancement-that is, better long-term memory for emotional than for neutral stimuli-and the emotion-induced recognition bias-that is, a more liberal response criterion for emotional than for neutral stimuli. Studies on visual emotion perception and attention suggest that emotion-related processes can be modulated by means of spatial-frequency filtering of the presented emotional stimuli. Specifically, low spatial frequencies are assumed to play a primary role for the influence of emotion on attention and judgment. Given this theoretical background, we investigated whether spatial-frequency filtering also impacts (1) the memory advantage for emotional faces and (2) the emotion-induced recognition bias, in a series of old/new recognition experiments. Participants completed incidental-learning tasks with high- (HSF) and low- (LSF) spatial-frequency-filtered emotional and neutral faces. The results of the surprise recognition tests showed a clear memory advantage for emotional stimuli. Most importantly, the emotional memory enhancement was significantly larger for face images containing only low-frequency information (LSF faces) than for HSF faces across all experiments, suggesting that LSF information plays a critical role in this effect, whereas the emotion-induced recognition bias was found only for HSF stimuli. We discuss our findings in terms of both the traditional account of different processing pathways for HSF and LSF information and a stimulus features account. The double dissociation in the results favors the latter account-that is, an explanation in terms of differences in the characteristics of HSF and LSF stimuli.

  2. The neurobiology of self-face recognition in depressed adolescents with low or high suicidality.

    Science.gov (United States)

    Quevedo, Karina; Ng, Rowena; Scott, Hannah; Martin, Jodi; Smyda, Garry; Keener, Matt; Oppenheimer, Caroline W

    2016-11-01

    This study sought to test whether the neurobiology of self-processing differentiated depressed adolescents with high suicidality (HS) from those with low suicidality (LS) and healthy controls (HC; N = 119, MAGE = 14.79, SD = 1.64, Min = 11.3, Max = 17.8). Participants completed a visual self-recognition task in the scanner during which they identified their own or an unfamiliar adolescent face across 3 emotional expressions (happy, neutral or sad). A 3-group (HS, LS, HC) by 2 within-subject factors (2 Self conditions [self, other] and 3 Emotions [happy, neutral, sad]) GLM yielded (a) a main effect of Self condition with all participants showing higher activity in the right occipital, precuneus and fusiform during the self- versus other-face conditions; (b) a main effect of Group where all depressed youth showed higher dorsolateral prefrontal cortex activity than HC across all conditions, and with HS showing higher cuneus and occipital activity versus both LS and HC; and (c) a Group by Self by Emotion interaction with HS showing lower activity in both mid parietal, limbic, and prefrontal areas in the Happy self versus other-face condition relative to the LS group, who in turn had less activity compared to HC youth. Covarying for depression severity replicated all results except the third finding; In this subsequent analysis, a Group by Self interaction showed that although HC had similar midline cortical structure (MCS) activity for all faces, LS showed higher MCS activity for the self versus other faces, whereas HS showed the opposite pattern. Results suggest that the neurophysiology of emotionally charged self-referential information can distinguish depressed, suicidal youth versus nonsuicidal depressed and healthy adolescents. Neurophysiological differences and implications for the prediction of suicidality in youth are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  3. Non-Cooperative Target Recognition by Means of Singular Value Decomposition Applied to Radar High Resolution Range Profiles

    Directory of Open Access Journals (Sweden)

    Patricia López-Rodríguez

    2014-12-01

    Full Text Available Radar high resolution range profiles are widely used among the target recognition community for the detection and identification of flying targets. In this paper, singular value decomposition is applied to extract the relevant information and to model each aircraft as a subspace. The identification algorithm is based on angle between subspaces and takes place in a transformed domain. In order to have a wide database of radar signatures and evaluate the performance, simulated range profiles are used as the recognition database while the test samples comprise data of actual range profiles collected in a measurement campaign. Thanks to the modeling of aircraft as subspaces only the valuable information of each target is used in the recognition process. Thus, one of the main advantages of using singular value decomposition, is that it helps to overcome the notable dissimilarities found in the shape and signal-to-noise ratio between actual and simulated profiles due to their difference in nature. Despite these differences, the recognition rates obtained with the algorithm are quite promising.

  4. Chiral perturbation theory with nucleons

    International Nuclear Information System (INIS)

    Meissner, U.G.

    1991-09-01

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

  5. One-Dimensional Chirality: Strong Optical Activity in Epsilon-Near-Zero Metamaterials.

    Science.gov (United States)

    Rizza, Carlo; Di Falco, Andrea; Scalora, Michael; Ciattoni, Alessandro

    2015-07-31

    We suggest that electromagnetic chirality, generally displayed by 3D or 2D complex chiral structures, can occur in 1D patterned composites whose components are achiral. This feature is highly unexpected in a 1D system which is geometrically achiral since its mirror image can always be superposed onto it by a 180 deg rotation. We analytically evaluate from first principles the bianisotropic response of multilayered metamaterials and we show that the chiral tensor is not vanishing if the system is geometrically one-dimensional chiral; i.e., its mirror image cannot be superposed onto it by using translations without resorting to rotations. As a signature of 1D chirality, we show that 1D chiral metamaterials support optical activity and we prove that this phenomenon undergoes a dramatic nonresonant enhancement in the epsilon-near-zero regime where the magnetoelectric coupling can become dominant in the constitutive relations.

  6. Chiral symmetry restoration and quasi-elastic electron-nucleus scattering

    International Nuclear Information System (INIS)

    Henley, E.M.; Krein, G.

    1989-01-01

    Chiral symmetry is known to be an important concept in hadronic interactions. It holds in QCD, but is known to be broken at low energies. It is therefore useful to study chiral symmetry and its breaking together with its consequences in nuclear physics. It is the latter phenomena we consider here. It is difficult to study nonperturbative QCD at low energies and models are needed. The Nambu-Jona-Lasinio (NJL) model fits this category; it incorporates chiral symmetry and its breaking, and allows one to study its effects in nucleons and nuclei. In particular, the constituent quark mass varies with density (ρ) and temperature (T). At high ρ and T chiral symmetry is restored. It is the ρ dependence which yields important effects in electron scattering due to partial restoration of chiral symmetry in nuclei. We begin with the NJL model with a small chiral symmetry breaking

  7. New remarks on chiral bosonization

    International Nuclear Information System (INIS)

    Souza Dutra, A. de

    1992-01-01

    We discuss a certain duality between the constraints appearing in ordinary Lagrangian density and its first order counterpart for the gauged Siegel chiral boson. It is demonstrated the equivalence, at the classical level, of the two versions of the gauged Siegel chiral boson to its corresponding gauged Floreanini-Jackiw chiral bosons. It is also argued that the most general constrained Lagrangian density, that leads to a bosonic field obeying a first order differential equation of motion and preserve simultaneously Lorentz invariance, is just the Floreanini-Jackiw one. (author)

  8. Nonlinear spectroscopic studies of chiral media

    International Nuclear Information System (INIS)

    Belkin, Mikhail Alexandrovich

    2004-01-01

    Molecular chirality plays an important role in chemistry, biology, and medicine. Traditional optical techniques for probing chirality, such as circular dichroism and Raman optical activity rely on electric-dipole forbidden transitions. As a result, their intrinsic low sensitivity limits their use to probe bulk chirality rather than chiral surfaces, monolayers or thin films often important for chemical or biological systems. Contrary to the traditional chirality probes, chiral signal in sum-frequency generation (SFG) is electric-dipole allowed both on chiral surface and in chiral bulk making it a much more promising tool for probing molecular chirality. SFG from a chiral medium was first proposed in 1965, but had never been experimentally confirmed until this thesis work was performed. This thesis describes a set of experiments successfully demonstrating that chiral SFG responses from chiral monolayers and liquids are observable. It shows that, with tunable inputs, SFG can be used as a sensitive spectroscopic tool to probe chirality in both electronic and vibrational resonances of chiral molecules. The monolayer sensitivity is feasible in both cases. It also discusses the relevant theoretical models explaining the origin and the strength of the chiral signal in vibrational and electronic SFG spectroscopies

  9. Delayed Video Self-Recognition in Children with High Vo Functioning Autism and Asperger's Disorder

    Science.gov (United States)

    Dissanayake, Cheryl; Shembrey, Joh; Suddendorf, Thomas

    2010-01-01

    Two studies are reported which investigate delayed video self-recognition (DSR) in children with autistic disorder and Asperger's disorder relative to one another and to their typically developing peers. A secondary aim was to establish whether DSR ability is dependent on metarepresentational ability. Children's verbal and affective responses to…

  10. Chiral fermions in asymptotically safe quantum gravity.

    Science.gov (United States)

    Meibohm, J; Pawlowski, J M

    2016-01-01

    We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.

  11. Deformed chiral nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Price, C E; Shepard, J R [Colorado Univ., Boulder (USA). Dept. of Physics

    1991-04-18

    We compute properties of the nucleon in a hybrid chiral model based on the linear {sigma}-model with quark degrees of freedom treated explicity. In contrast to previous calculations, we do not use the hedgehog ansatz. Instead we solve self-consistently for a state with well defined spin and isospin projections. We allow this state to be deformed and find that, although d- and g-state admixtures in the predominantly s-state single quark wave functions are not large, they have profound effects on many nucleon properties including magnetic moments and g{sub A}. Our best fit parameters provide excellent agreement with experiment but are much different from those determined in hedgehog calculations. (orig.).

  12. Amino Acids and Chirality

    Science.gov (United States)

    Cook, Jamie E.

    2012-01-01

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

  13. Nuclear matter from chiral effective field theory

    International Nuclear Information System (INIS)

    Drischler, Christian

    2017-01-01

    Nuclear matter is an ideal theoretical system that provides key insights into the physics of different length scales. While recent ab initio calculations of medium-mass to heavy nuclei have demonstrated that realistic saturation properties in infinite matter are crucial for reproducing experimental binding energies and charge radii, the nuclear-matter equation of state allows tight constraints on key quantities of neutron stars. In the present thesis we take advantage of both aspects. Chiral effective field theory (EFT) with pion and nucleon degrees of freedom has become the modern low-energy approach to nuclear forces based on the symmetries of quantum chromodynamics, the fundamental theory of strong interactions. The systematic chiral expansion enables improvable calculations associated with theoretical uncertainty estimates. In recent years, chiral many-body forces were derived up to high orders, allowing consistent calculations including all many-body contributions at next-to-next-to-next-to-leading order (N 3 LO). Many further advances have driven the construction of novel chiral potentials with different regularization schemes. Here, we develop advanced methods for microscopic calculations of the equation of state of homogeneous nuclear matter with arbitrary proton-to-neutron ratio at zero temperature. Specifically, we push the limits of many-body perturbation theory (MBPT) considerations to high orders in the chiral and in the many-body expansion. To address the challenging inclusion of three-body forces, we introduce a new partial-wave method for normal ordering that generalizes the treatment of these contributions. We show improved predictions for the neutron-matter equation of state with consistent N 3 LO nucleon-nucleon (NN) plus three-nucleon (3N) potentials using MBPT up to third order and self-consistent Green's function theory. The latter also provides nonperturbative benchmarks for the many-body convergence. In addition, we extend the normal

  14. Nuclear matter from chiral effective field theory

    Energy Technology Data Exchange (ETDEWEB)

    Drischler, Christian

    2017-11-15

    Nuclear matter is an ideal theoretical system that provides key insights into the physics of different length scales. While recent ab initio calculations of medium-mass to heavy nuclei have demonstrated that realistic saturation properties in infinite matter are crucial for reproducing experimental binding energies and charge radii, the nuclear-matter equation of state allows tight constraints on key quantities of neutron stars. In the present thesis we take advantage of both aspects. Chiral effective field theory (EFT) with pion and nucleon degrees of freedom has become the modern low-energy approach to nuclear forces based on the symmetries of quantum chromodynamics, the fundamental theory of strong interactions. The systematic chiral expansion enables improvable calculations associated with theoretical uncertainty estimates. In recent years, chiral many-body forces were derived up to high orders, allowing consistent calculations including all many-body contributions at next-to-next-to-next-to-leading order (N{sup 3}LO). Many further advances have driven the construction of novel chiral potentials with different regularization schemes. Here, we develop advanced methods for microscopic calculations of the equation of state of homogeneous nuclear matter with arbitrary proton-to-neutron ratio at zero temperature. Specifically, we push the limits of many-body perturbation theory (MBPT) considerations to high orders in the chiral and in the many-body expansion. To address the challenging inclusion of three-body forces, we introduce a new partial-wave method for normal ordering that generalizes the treatment of these contributions. We show improved predictions for the neutron-matter equation of state with consistent N{sup 3}LO nucleon-nucleon (NN) plus three-nucleon (3N) potentials using MBPT up to third order and self-consistent Green's function theory. The latter also provides nonperturbative benchmarks for the many-body convergence. In addition, we extend the

  15. Chiral fermions on the lattice

    International Nuclear Information System (INIS)

    Randjbar Daemi, S.; Strathdee, J.

    1995-01-01

    The overlap approach to chiral gauge theories on arbitrary D-dimensional lattices is studied. The doubling problem and its relation to chiral anomalies for D = 2 and 4 is examined. In each case it is shown that the doublers can be eliminated and the well known perturbative results for chiral anomalies can be recovered. We also consider the multi-flavour case and give the general criteria for the construction of anomaly free chiral gauge theories on arbitrary lattices. We calculate the second order terms in a continuum approximation to the overlap formula in D dimensions and show that they coincide with the bilinear part of the effective action of D-dimensional Weyl fermions coupled to a background gauge field. Finally, using the same formalism we reproduce the correct Lorentz, diffeomorphism and gauge anomalies in the coupling of a Weyl fermion to 2-dimensional gravitation and Maxwell fields. (author). 15 refs

  16. Switching of chirality by light

    NARCIS (Netherlands)

    Feringa, B.L.; Schoevaars, A.M; Jager, W.F.; de Lange, B.; Huck, N.P.M.

    1996-01-01

    Optically active photoresponsive molecules are described by which control of chirality is achieved by light. These chiroptical molecular switches are based on inherently dissymmetric overcrowded alkenes and the synthesis, resolution and dynamic stereochemical properties are discussed. Introduction

  17. Chiral topological insulator of magnons

    Science.gov (United States)

    Li, Bo; Kovalev, Alexey A.

    2018-05-01

    We propose a magnon realization of 3D topological insulator in the AIII (chiral symmetry) topological class. The topological magnon gap opens due to the presence of Dzyaloshinskii-Moriya interactions. The existence of the topological invariant is established by calculating the bulk winding number of the system. Within our model, the surface magnon Dirac cone is protected by the sublattice chiral symmetry. By analyzing the magnon surface modes, we confirm that the backscattering is prohibited. By weakly breaking the chiral symmetry, we observe the magnon Hall response on the surface due to opening of the gap. Finally, we show that by changing certain parameters, the system can be tuned between the chiral topological insulator, three-dimensional magnon anomalous Hall, and Weyl magnon phases.

  18. Review of chiral perturbation theory

    Indian Academy of Sciences (India)

    Abstract. 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.

  19. Chirality-controlled crystallization via screw dislocations.

    Science.gov (United States)

    Sung, Baeckkyoung; de la Cotte, Alexis; Grelet, Eric

    2018-04-11

    Chirality plays an important role in science from enantiomeric separation in chemistry to chiral plasmonics in nanotechnology. However, the understanding of chirality amplification from chiral building blocks to ordered helical superstructures remains a challenge. Here, we demonstrate that topological defects, such as screw dislocations, can drive the chirality transfer from particle to supramolecular structure level during the crystallization process. By using a model system of chiral particles, which enables direct imaging of single particle incorporation into growing crystals, we show that the crystallization kinetic pathway is the key parameter for monitoring, via the defects, the chirality amplification of the crystalline structures from racemic to predominantly homohelical. We provide an explanation based on the interplay between geometrical frustration, racemization induced by thermal fluctuations, and particle chirality. Our results demonstrate that screw dislocations not only promote the growth, but also control the chiral morphology and therefore the functionality of crystalline states.

  20. 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.

  1. 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....

  2. Chiral thermodynamics of nuclear matter

    International Nuclear Information System (INIS)

    Fiorilla, Salvatore

    2012-01-01

    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.

  3. Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

    Directory of Open Access Journals (Sweden)

    Ángela Valentín-Pérez

    2018-03-01

    Full Text Available Herein, we report the preparation of chiral, one-dimensional coordination polymers based on trinuclear paddlewheel helices [M3(dpa4]2+ (M = Co(II and Ni(II; dpa = the anion of 2,2′-dipyridylamine. Enantiomeric resolution of a racemic mixture of [M3(dpa4]2+ complexes was achieved by chiral recognition of the respective enantiomer by [Δ-As2(tartrate2]2− or [Λ-As2(tartrate2]2− in N,N-dimethylformamide (DMF, affording crystalline coordination polymers formed from [(Δ-Co3(dpa4(Λ-As2(tartrate2]·3DMF (Δ-1, [(Λ-Co3(dpa4(Δ-As2(tartrate2]·3DMF (Λ-1, [(Δ-Ni3(dpa4(Λ-As2(tartrate2]·(4 − nDMF∙nEt2O (Δ-2 or [(Λ-Ni3(dpa4(Δ-As2(tartrate2]·(4 − nDMF∙nEt2O (Λ-2 repeating units. UV-visible circular dichroism spectra of the complexes in DMF solutions demonstrate the efficient isolation of optically active species. The helicoidal [M3(dpa4]2+ units that were obtained display high stability towards racemization as shown by the absence of an evolution of the dichroic signals after several days at room temperature and only a small decrease of the signal after 3 h at 80 °C.

  4. Chiral imprinted polymers as enantiospecific coatings of stir bar sorptive extraction devices.

    Science.gov (United States)

    Gomez-Caballero, Alberto; Guerreiro, Antonio; Karim, Kal; Piletsky, Sergey; Goicolea, M Aranzazu; Barrio, Ramon J

    2011-10-15

    This paper reports the design of Molecularly Imprinted Polymers (MIP) with affinity towards (S)-citalopram using computational modeling for the selection of functional monomers and monomer:template ratio. Acrylamide was selected as functional monomer and the final complex functional monomer/template resulted in a 3:1 ratio. The polymer was synthesized by radical polymerization initiated by UV onto magnetic stir-bars in order to obtain a stir bar sorptive extraction (SBSE) device capable of selective enantiomeric recognition. After successful template removal, the parameters affecting the SBSE procedure (sample volume, ionic strength, extraction time and pH) were optimized for the effective rebinding of the target analyte. The resultant chirally imprinted polymer based stir-bar was able to selectively extract (S)-citalopram from a racemic mixture in an aqueous media with high specificity (specificity factor 4) between 25 and 500 μgL(-1). The MIP coated stir-bars can have significance for enantiospecific sample pre-concentration and subsequent analysis without the need for any chiral chromatographic separation. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. [[Chiral separation of five arylpropionic acid drugs and determination of their enantiomers in pharmaceutical preparations by reversed-phase high performance liquid chromatography with cellulose-tris-(4-methylbenzoate) stationary phase

    Science.gov (United States)

    Luo, An; Wan, Qiang; Fan, Huajun; Chen, Zhi; Wu, Xuehao; Huang, Xiaowen; Zang, Linquan

    2014-09-01

    Chromatographic behaviors for enantiomeric separation of arylpropionic acid drugs were systematically developed by reversed phase-high performance liquid chromatography (RP-HPLC) using cellulose-tris-(4-methylbenzoate) (CTMB) as chiral stationary phase (CSP). The effects of the composition of the mobile phase, additives and temperature on chiral separation of flurbiprofen, pranoprofen, naproxen, ibuprofen and loxoprofen were further investigated. The enantiomers had been successfully separated on CSP of CTMB by the mobile phase of methanol-0.1% (v/v) formic acid except naproxen by acetonitrile-0.1% (v/v) formic acid at 25 °C. The mechanisms of the racemic resolution for the above mentioned five drugs are discussed thermodynamically and structurally. The resolutions between respective enantiomers for arylpropionic acid drugs on CTMB had significant differences due to their chromatographic behaviors. The order of resolutions ranked pranoprofen, loxoprofen, flurbiprofen, ibuprofen and naproxen. The method established has been successfully applied to the determination of the enantiomers of the five drugs in commercial preparations under the optimized conditions. It proved that the method is simple, reliable and accurate.

  6. Highly sensitive trivalent copper chelate–luminol chemiluminescence system for capillary electrophoresis chiral separation and determination of ofloxacin enantiomers in urine samples

    Directory of Open Access Journals (Sweden)

    Hao-Yue Xie

    2014-12-01

    Full Text Available A simple, fast and sensitive capillary electrophoresis (CE strategy combined with chemiluminescence (CL detection for analysis of ofloxacin (OF enantiomers was established in the present work. Sulfonated β-cyclodextrin (β-CD was used as the chiral additive being added into the running buffer of luminol–diperiodatocuprate (III (K5[Cu(HIO62], DPC chemiluminescence system. Under the optimum conditions, the proposed method was successfully applied to separation and analysis of OF enantiomers with the detection limits (S/N=3 of 8.0 nM and 7.0 nM for levofloxacin and dextrofloxacin, respectively. The linear ranges were both 0.010–100 μM. The method was utilized for analyzing OF in urine; the results obtained were satisfactory and recoveries were 89.5–110.8%, which demonstrated the reliability of this method. This approach can also be further extended to analyze different commercial OF medicines. Keywords: Ofloxacin, Chiral analysis, Sulfonated-β-CD, Capillary electrophoresis, Chemiluminescence

  7. Separation of the stereoisomers of the main metabolite of a non-steroidal anti-inflammatory drug, flobufen, by chiral high-performance liquid chromatography.

    Science.gov (United States)

    Wsól, V; Fell, A F; Kvasnicková, E; Hais, I M

    1997-02-07

    The major metabolite of a novel non-steroidal anti-inflammatory drug, DL-4-(2',4'-difluorobiphenyl-4-yl)-2-oxo-2-methylbutanoic acid (flobufen, I), namely 4-(2',4'-difluorobiphenyl-4-yl)-2-methyl-gamma-butyrolactone (4-dihydroflobufen lactone, III), has four stereoisomers consisting of two racemic pairs of enantiomers. Of three chiral stationary phases tested, Cyclobond I beta-RSP (Astec) (beta-cylodextrin derivatized with R,S-hydroxypropyl) was best able to separate the (+2)(--) racemate, with a liquid phase containing acetonitrile as modifier and triethylamine acetate as buffer. Using the Box-Wilson Central Composite Design for three factors, an optimum combination of pH and concentrations of the modifier and buffer was eventually obtained. A chromatographic response function based on a combination of the Kaiser peak separation function, Pi, and retention time of the second eluting enantiomer, tRL, served as a response criterion for the process of optimization. The optimum conditions developed for the (+2)(--) racemate were also found to be suitable for separating the (+-)(-+) racemate, for which earlier studies had shown the separation to be more facile. Separation of the four stereoisomers of III, for which the chiral chromatographic system optimized in this study is proposed as the second stage, is targeted at a biochemical study of the stereoisomeric metabolism of I.

  8. Macdonald index and chiral algebra

    Science.gov (United States)

    Song, Jaewon

    2017-08-01

    For any 4d N = 2 SCFT, there is a subsector described by a 2d chiral algebra. The vacuum character of the chiral algebra reproduces the Schur index of the corresponding 4d theory. The Macdonald index counts the same set of operators as the Schur index, but the former has one more fugacity than the latter. We conjecture a prescription to obtain the Macdonald index from the chiral algebra. The vacuum module admits a filtration, from which we construct an associated graded vector space. From this grading, we conjecture a notion of refined character for the vacuum module of a chiral algebra, which reproduces the Macdonald index. We test this prescription for the Argyres-Douglas theories of type ( A 1 , A 2 n ) and ( A 1 , D 2 n+1) where the chiral algebras are given by Virasoro and \\widehat{su}(2) affine Kac-Moody algebra. When the chiral algebra has more than one family of generators, our prescription requires a knowledge of the generators from the 4d.

  9. Adversity, emotion recognition, and empathic concern in high-risk youth.

    Directory of Open Access Journals (Sweden)

    Jodi A Quas

    Full Text Available Little is known about how emotion recognition and empathy jointly operate in youth growing up in contexts defined by persistent adversity. We investigated whether adversity exposure in two groups of youth was associated with reduced empathy and whether deficits in emotion recognition mediated this association. Foster, rural poor, and comparison youth from Swaziland, Africa identified emotional expressions and rated their empathic concern for characters depicted in images showing positive, ambiguous, and negative scenes. Rural and foster youth perceived greater anger and happiness in the main characters in ambiguous and negative images than did comparison youth. Rural children also perceived less sadness. Youth's perceptions of sadness in the negative and ambiguous expressions mediated the relation between adversity and empathic concern, but only for the rural youth, who perceived less sadness, which then predicted less empathy. Findings provide new insight into processes that underlie empathic tendencies in adversity-exposed youth and highlight potential directions for interventions to increase empathy.

  10. A High Performance Banknote Recognition System Based on a One-Dimensional Visible Light Line Sensor.

    Science.gov (United States)

    Park, Young Ho; Kwon, Seung Yong; Pham, Tuyen Danh; Park, Kang Ryoung; Jeong, Dae Sik; Yoon, Sungsoo

    2015-06-15

    An algorithm for recognizing banknotes is required in many fields, such as banknote-counting machines and automatic teller machines (ATM). Due to the size and cost limitations of banknote-counting machines and ATMs, the banknote image is usually captured by a one-dimensional (line) sensor instead of a conventional two-dimensional (area) sensor. Because the banknote image is captured by the line sensor while it is moved at fast speed through the rollers inside the banknote-counting machine or ATM, misalignment, geometric distortion, and non-uniform illumination of the captured images frequently occur, which degrades the banknote recognition accuracy. To overcome these problems, we propose a new method for recognizing banknotes. The experimental results using two-fold cross-validation for 61,240 United States dollar (USD) images show that the pre-classification error rate is 0%, and the average error rate for the final recognition of the USD banknotes is 0.114%.

  11. Development and validation of a chiral high-performance liquid chromatography assay for rogletimide and rogletimide-N-oxide isomers in plasma.

    Science.gov (United States)

    Etienne, M C; Oster, W; Milano, G

    1996-01-01

    The purpose of the present study was to develop and validate a stereo-specific high-performance liquid chromatography (HPLC) assay for rogletimide (Rog) and rogletimide-N-oxide (Nox) isomers in plasma. The assay was performed with a chiral cellulose-[4-methylbenzoate]ester column (Chiracel OJ). Optimal separation was achieved isocratically with a mobile phase consisting of n-hexane/anhydrous ethanol (65/35, v/v) at a flow rate of 0.9 ml/min, with the column being thermostated at +35 degrees C (UV detection at 257 nm). Under these conditions, retention times were approximately 17, 28, 31 and 76 min for R-Rog, S-Rog, R-Nox and S-Nox, respectively. S-aminoglutethimide (S-Ag) served as the internal standard (retention time 70 min). An extraction procedure from plasma samples was developed on Bond Elut RP8 500-mg cartridges; conditioning was performed with 5 ml methanol and 5 ml water, after which 1 ml plasma that had previously been spiked with 5 microM S-Ag was applied. Washing was done with 6 ml water and elution, with 4 ml methanol. After evaporation to dryness, residues were dissolved in 400 microliters anhydrous ethanol and 12-48 microliters was injected onto the HPLC system. Blank plasma from healthy donors showed the random presence of a small interference eluting at the retention time of R-Rog, precluding the accurate quantification of R-Rog concentrations below 2.5 microM. Reproducibility assays demonstrated the need to use an internal standard. Taking into account the internal standard, at 2.5 microM the intra- and inter-assay coefficients of variation were 10.5% and 21.0% for R-Rog 5.5% and 8.7% for S-Rog, 7.6% and 20.8% for R-Nox and 11.7% and 6.4% for S-Nox, respectively. The detection limit was 2.5 microM for R-Rog, 0.5 microM for S-Rog, 0.25 microM for R-Nox and 0.5 microM for S-Nox. Linearity was satisfactory at concentrations ranging from 2.5 to 10 microM for R-Rog, from 0.5 to 10 microM for S-Rog, from 0.25 to 2.5 microM for R-Nox and from 0.50 to 2

  12. Amino-acid- and peptide-directed synthesis of chiral plasmonic gold nanoparticles.

    Science.gov (United States)

    Lee, Hye-Eun; Ahn, Hyo-Yong; Mun, Jungho; Lee, Yoon Young; Kim, Minkyung; Cho, Nam Heon; Chang, Kiseok; Kim, Wook Sung; Rho, Junsuk; Nam, Ki Tae

    2018-04-01

    Understanding chirality, or handedness, in molecules is important because of the enantioselectivity that is observed in many biochemical reactions 1 , and because of the recent development of chiral metamaterials with exceptional light-manipulating capabilities, such as polarization control 2-4 , a negative refractive index 5 and chiral sensing 6 . Chiral nanostructures have been produced using nanofabrication techniques such as lithography 7 and molecular self-assembly 8-11 , but large-scale and simple fabrication methods for three-dimensional chiral structures remain a challenge. In this regard, chirality transfer represents a simpler and more efficient method for controlling chiral morphology 12-18 . Although a few studies 18,19 have described the transfer of molecular chirality into micrometre-sized helical ceramic crystals, this technique has yet to be implemented for metal nanoparticles with sizes of hundreds of nanometres. Here we develop a strategy for synthesizing chiral gold nanoparticles that involves using amino acids and peptides to control the optical activity, handedness and chiral plasmonic resonance of the nanoparticles. The key requirement for achieving such chiral structures is the formation of high-Miller-index surfaces ({hkl}, h ≠ k ≠ l ≠ 0) that are intrinsically chiral, owing to the presence of 'kink' sites 20-22 in the nanoparticles during growth. The presence of chiral components at the inorganic surface of the nanoparticles and in the amino acids and peptides results in enantioselective interactions at the interface between these elements; these interactions lead to asymmetric evolution of the nanoparticles and the formation of helicoid morphologies that consist of highly twisted chiral elements. The gold nanoparticles that we grow display strong chiral plasmonic optical activity (a dis-symmetry factor of 0.2), even when dispersed randomly in solution; this observation is supported by theoretical calculations and direct

  13. Spin-Selective Transmission and Devisable Chirality in Two-Layer Metasurfaces.

    Science.gov (United States)

    Li, Zhancheng; Liu, Wenwei; Cheng, Hua; Chen, Shuqi; Tian, Jianguo

    2017-08-15

    Chirality is a nearly ubiquitous natural phenomenon. Its minute presence in most naturally occurring materials makes it incredibly difficult to detect. Recent advances in metasurfaces indicate that they exhibit devisable chirality in novel forms; this finding offers an effective opening for studying chirality and its features in such nanostructures. These metasurfaces display vast possibilities for highly sensitive chirality discrimination in biological and chemical systems. Here, we show that two-layer metasurfaces based on twisted nanorods can generate giant spin-selective transmission and support engineered chirality in the near-infrared region. Two designed metasurfaces with opposite spin-selective transmission are proposed for treatment as enantiomers and can be used widely for spin selection and enhanced chiral sensing. Specifically, we demonstrate that the chirality in these proposed metasurfaces can be adjusted effectively by simply changing the orientation angle between the twisted nanorods. Our results offer simple and straightforward rules for chirality engineering in metasurfaces and suggest intriguing possibilities for the applications of such metasurfaces in spin optics and chiral sensing.

  14. Capillary electrophoresis of covalently functionalized single-chirality carbon nanotubes.

    Science.gov (United States)

    He, Pingli; Meany, Brendan; Wang, Chunyan; Piao, Yanmei; Kwon, Hyejin; Deng, Shunliu; Wang, YuHuang

    2017-07-01

    We demonstrate the separation of chirality-enriched single-walled carbon nanotubes (SWCNTs) by degree of surface functionalization using high-performance CE. Controlled amounts of negatively charged and positively charged functional groups were attached to the sidewall of chirality-enriched SWCNTs through covalent functionalization using 4-carboxybenzenediazonium tetrafluoroborate or 4-diazo-N,N-diethylaniline tetrafluoroborate, respectively. Surfactant- and pH-dependent studies confirmed that under conditions that minimized ionic screening effects, separation of these functionalized SWCNTs was strongly dependent on the surface charge density introduced through covalent surface chemistry. For both heterogeneous mixtures and single-chirality-enriched samples, covalently functionalized SWCNTs showed substantially increased peak width in electropherogram spectra compared to nonfunctionalized SWCNTs, which can be attributed to a distribution of surface charges along the functionalized nanotubes. Successful separation of functionalized single-chirality SWCNTs by functional density was confirmed with UV-Vis-NIR absorption and Raman scattering spectroscopies of fraction collected samples. These results suggest a high degree of structural heterogeneity in covalently functionalized SWCNTs, even for chirality-enriched samples, and show the feasibility of applying CE for high-performance separation of nanomaterials based on differences in surface functional density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Iridium-Catalyzed Asymmetric Intramolecular Allylic Amidation : Enantioselective Synthesis of Chiral Tetrahydroisoquinolines and Saturated Nitrogen Heterocycles

    NARCIS (Netherlands)

    Teichert, Johannes F.; Fañanás-Mastral, Martín; Feringa, Bernard

    2011-01-01

    For the first time iridium catalysis has been used for the synthesis of chiral tetrahydroisoquinolines with excellent yields and high enantioselectivities (see scheme; cod=1,5-cyclooctadiene, DBU=1,8-diazabicyclo[5.4.0]undec-7-ene). These products are important chiral building blocks for the

  16. A high-fat high-sugar diet-induced impairment in place-recognition memory is reversible and training-dependent.

    Science.gov (United States)

    Tran, Dominic M D; Westbrook, R Frederick

    2017-03-01

    A high-fat high-sugar (HFHS) diet is associated with cognitive deficits in people and produces spatial learning and memory deficits in rodents. Notable, such diets rapidly impair place-, but not object-recognition memory in rats within one week of exposure. Three experiments examined whether this impairment was reversed by removal of the diet, or prevented by pre-diet training. Experiment 1 showed that rats switched from HFHS to chow recovered from the place-recognition impairment that they displayed while on HFHS. Experiment 2 showed that control rats ("Untrained") who were exposed to an empty testing arena while on chow, were impaired in place-recognition when switched to HFHS and tested for the first time. However, rats tested ("Trained") on the place and object task while on chow, were protected from the diet-induce deficit and maintained good place-recognition when switched to HFHS. Experiment 3 examined the conditions of this protection effect by training rats in a square arena while on chow, and testing them in a rectangular arena while on HFHS. We have previously demonstrated that chow rats, but not HFHS rats, show geometry-based reorientation on a rectangular arena place-recognition task (Tran & Westbrook, 2015). Experiment 3 assessed whether rats switched to the HFHS diet after training on the place and object tasks in a square area, would show geometry-based reorientation in a rectangular arena. The protective benefit of training was replicated in the square arena, but both Untrained and Trained HFHS failed to show geometry-based reorientation in the rectangular arena. These findings are discussed in relation to the specificity of the training effect, the role of the hippocampus in diet-induced deficits, and their implications for dietary effects on cognition in people. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. A microprocessor-based single board computer for high energy physics event pattern recognition

    International Nuclear Information System (INIS)

    Bernstein, H.; Gould, J.J.; Imossi, R.; Kopp, J.K.; Love, W.A.; Ozaki, S.; Platner, E.D.; Kramer, M.A.

    1981-01-01

    A single board MC 68000 based computer has been assembled and bench marked against the CDC 7600 running portions of the pattern recognition code used at the MPS. This computer has a floating coprocessor to achieve throughputs equivalent to several percent that of the 7600. A major part of this work was the construction of a FORTRAN compiler including assembler, linker and library. The intention of this work is to assemble a large number of these single board computers in a parallel FASTBUS environment to act as an on-line and off-line filter for the raw data from MPS II and ISABELLE experiments. (orig.)

  18. Microprocessor-based single board computer for high energy physics event pattern recognition

    International Nuclear Information System (INIS)

    Bernstein, H.; Gould, J.J.; Imossi, R.; Kopp, J.K.; Love, W.A.; Ozaki, S.; Platner, E.D.; Kramer, M.A.

    1981-01-01

    A single board MC 68000 based computer has been assembled and bench marked against the CDC 7600 running portions of the pattern recognition code used at the MPS. This computer has a floating coprocessor to achieve throughputs equivalent to several percent that of the 7600. A major part of this work was the construction of a FORTRAN compiler including assembler, linker and library. The intention of this work is to assemble a large number of these single board computers in a parallel FASTBUS environment to act as an on-line and off-line filter for the raw data from MPS II and ISABELLE experiments

  19. Chiral memory via chiral amplification and selective depolymerization of porphyrin aggregates

    NARCIS (Netherlands)

    Helmich, F.A.; Lee, C.C.; Schenning, A.P.H.J.; Meijer, E.W.

    2010-01-01

    Chiral memory at the supramolecular level is obtained via a new approach using chiral Zn porphrins and achiral Cu porphyrins. In a "sergeant-and-soldiers" experiment, the Zn "sergeant" transfers its own chirality to Cu "soldiers" and, after chiral amplification, the "sergeant" is removed from the

  20. Effects of chirality and surface stresses on the bending and buckling of chiral nanowires

    International Nuclear Information System (INIS)

    Wang, Jian-Shan; Shimada, Takahiro; Kitamura, Takayuki; Wang, Gang-Feng

    2014-01-01

    Due to their superior optical, elastic and electrical properties, chiral nanowires have many applications as sensors, probes, and building blocks of nanoelectromechanical systems. In this paper, we develop a refined Euler–Bernoulli beam model for chiral nanowires with surface effects and material chirality incorporated. This refined model is employed to investigate the bending and buckling of chiral nanowires. It is found that surface effects and material chirality significantly affect the elastic behaviour of chiral nanowires. This study is helpful not only for understanding the size-dependent behaviour of chiral nanowires, but also for characterizing their mechanical properties. (paper)

  1. Pattern recognition

    CERN Document Server

    Theodoridis, Sergios

    2003-01-01

    Pattern recognition is a scientific discipline that is becoming increasingly important in the age of automation and information handling and retrieval. Patter Recognition, 2e covers the entire spectrum of pattern recognition applications, from image analysis to speech recognition and communications. This book presents cutting-edge material on neural networks, - a set of linked microprocessors that can form associations and uses pattern recognition to ""learn"" -and enhances student motivation by approaching pattern recognition from the designer's point of view. A direct result of more than 10

  2. Recent developments in pattern recognition with applications in high-energy physics

    International Nuclear Information System (INIS)

    Bischof, H.; Fruehwirth, R.

    1998-01-01

    In this contribution we consider the track finding and fitting problem from the pattern recognition and computer vision point of view. In particular, we consider it as a problem of recovering parametric models from noisy measurements. We review major approaches like neural networks, Hough transforms, Kalman filtering techniques, etc, which have been previously used in that area, and point out the problems of these approaches. Then we present an algorithm, originally developed in the area of computer vision, to fit different types of curves to noisy edge data, and demonstrate how it can be used for track finding and fitting. The algorithm is based on two principles: (a) a data driven exploration produces many hypotheses of possible tracks; (b) a selection procedure based on the Minimum Description Length Principle (MDL), selects those hypotheses which are needed to explain the data. The results of the algorithm are a number of tracks, and a set of outlier points (which cannot be explained by tracks according to the MDL-principle). We discuss how knowledge about the detectors and the underlying processes can be incorporated in the algorithm. Finally, we demonstrate the algorithm on 2D and 3D pattern recognition tasks. (author)

  3. A High Performance Banknote Recognition System Based on a One-Dimensional Visible Light Line Sensor

    Directory of Open Access Journals (Sweden)

    Young Ho Park

    2015-06-01

    Full Text Available An algorithm for recognizing banknotes is required in many fields, such as banknote-counting machines and automatic teller machines (ATM. Due to the size and cost limitations of banknote-counting machines and ATMs, the banknote image is usually captured by a one-dimensional (line sensor instead of a conventional two-dimensional (area sensor. Because the banknote image is captured by the line sensor while it is moved at fast speed through the rollers inside the banknote-counting machine or ATM, misalignment, geometric distortion, and non-uniform illumination of the captured images frequently occur, which degrades the banknote recognition accuracy. To overcome these problems, we propose a new method for recognizing banknotes. The experimental results using two-fold cross-validation for 61,240 United States dollar (USD images show that the pre-classification error rate is 0%, and the average error rate for the final recognition of the USD banknotes is 0.114%.

  4. Emotion recognition through static faces and moving bodies: a comparison between typically-developed adults and individuals with high level of autistic traits

    OpenAIRE

    Rossana eActis-Grosso; Rossana eActis-Grosso; Francesco eBossi; Paola eRicciardelli; Paola eRicciardelli

    2015-01-01

    We investigated whether the type of stimulus (pictures of static faces vs. body motion) contributes differently to the recognition of emotions. The performance (accuracy and response times) of 25 Low Autistic Traits (LAT group) young adults (21 males) and 20 young adults (16 males) with either High Autistic Traits (HAT group) or with High Functioning Autism Spectrum Disorder was compared in the recognition of four emotions (Happiness, Anger, Fear and Sadness) either shown in static faces or c...

  5. Emotion recognition through static faces and moving bodies: a comparison between typically developed adults and individuals with high level of autistic traits

    OpenAIRE

    Actis-Grosso, Rossana; Bossi, Francesco; Ricciardelli, Paola

    2015-01-01

    We investigated whether the type of stimulus (pictures of static faces vs. body motion) contributes differently to the recognition of emotions. The performance (accuracy and response times) of 25 Low Autistic Traits (LAT group) young adults (21 males) and 20 young adults (16 males) with either High Autistic Traits or with High Functioning Autism Spectrum Disorder (HAT group) was compared in the recognition of four emotions (Happiness, Anger, Fear, and Sadness) either shown in static faces or ...

  6. 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.

  7. Chiral Thirring–Wess model

    International Nuclear Information System (INIS)

    Rahaman, Anisur

    2015-01-01

    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

  8. What's wrong with anomalous chiral gauge theory?

    International Nuclear Information System (INIS)

    Kieu, T.D.

    1994-05-01

    It is argued on general ground and demonstrated in the particular example of the Chiral Schwinger Model that there is nothing wrong with apparently anomalous chiral gauge theory. If quantised correctly, there should be no gauge anomaly and chiral gauge theory should be renormalisable and unitary, even in higher dimensions and with non-Abelian gauge groups. Furthermore, it is claimed that mass terms for gauge bosons and chiral fermions can be generated without spoiling the gauge invariance. 19 refs

  9. Chirality: a relational geometric-physical property.

    Science.gov (United States)

    Gerlach, Hans

    2013-11-01

    The definition of the term chirality by Lord Kelvin in 1893 and 1904 is analyzed by taking crystallography at that time into account. This shows clearly that chirality is a relational geometric-physical property, i.e., two relations between isometric objects are possible: homochiral or heterochiral. In scientific articles the relational term chirality is often mistaken for the two valued measure for the individual (absolute) sense of chirality, an arbitrary attributive term. © 2013 Wiley Periodicals, Inc.

  10. Extreme chirality in Swiss roll metamaterials

    International Nuclear Information System (INIS)

    Demetriadou, A; Pendry, J B

    2009-01-01

    The chiral Swiss roll metamaterial is a resonant, magnetic medium that exhibits a negative refractive band for one-wave polarization. Its unique structure facilitates huge chiral effects: a plane polarized wave propagating through this system can change its polarization by 90 deg. in less than a wavelength. Such chirality is at least 100 times greater than previous structures have achieved. In this paper, we discuss this extreme chiral behaviour with both numerical and analytical results.

  11. 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

  12. Measuring the electromagnetic chirality of 2D arrays under normal illumination.

    Science.gov (United States)

    Garcia-Santiago, X; Burger, S; Rockstuhl, C; Fernandez-Corbaton, I

    2017-10-15

    We present an electromagnetic chirality measure for 2D arrays of subwavelength periodicities under normal illumination. The calculation of the measure uses only the complex reflection and transmission coefficients from the array. The measure allows the ordering of arrays according to their electromagnetic chirality, which further allows a quantitative comparison of different design strategies. The measure is upper bounded, and the extreme properties of objects with high values of electromagnetic chirality make them useful in both near- and far-field applications. We analyze the consequences that different possible symmetries of the array have on its electromagnetic chirality. We use the measure to study four different arrays. The results indicate the suitability of helices for building arrays of high electromagnetic chirality, and the low effectiveness of a substrate for breaking the transverse mirror symmetry.

  13. Chiral measurements with the Fixed-Point Dirac operator and construction of chiral currents

    International Nuclear Information System (INIS)

    Hasenfratz, P.; Hauswirth, S.; Holland, K.; Joerg, T.; Niedermayer, F.

    2002-01-01

    In this preliminary study, we examine the chiral properties of the parametrized Fixed-Point Dirac operator D FP , see how to improve its chirality via the Overlap construction, measure the renormalized quark condensate Σ-circumflex and the topological susceptibility χ t , and investigate local chirality of near zero modes of the Dirac operator. We also give a general construction of chiral currents and densities for chiral lattice actions

  14. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ehbert, D.

    1980-01-01

    The pion polarizability is calculated in a chiral meson-quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Lanta and Tarrach is given. The results of the paper give evidence to the nonlinear chiral Lagrangian favour

  15. Quenched Chiral Perturbation Theory to one loop

    NARCIS (Netherlands)

    Colangelo, G.; Pallante, E.

    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

  16. Variational approach to chiral quark models

    Energy Technology Data Exchange (ETDEWEB)

    Futami, Yasuhiko; Odajima, Yasuhiko; Suzuki, Akira

    1987-03-01

    A variational approach is applied to a chiral quark model to test the validity of the perturbative treatment of the pion-quark interaction based on the chiral symmetry principle. It is indispensably related to the chiral symmetry breaking radius if the pion-quark interaction can be regarded as a perturbation.

  17. A variational approach to chiral quark models

    International Nuclear Information System (INIS)

    Futami, Yasuhiko; Odajima, Yasuhiko; Suzuki, Akira.

    1987-01-01

    A variational approach is applied to a chiral quark model to test the validity of the perturbative treatment of the pion-quark interaction based on the chiral symmetry principle. It is indispensably related to the chiral symmetry breaking radius if the pion-quark interaction can be regarded as a perturbation. (author)

  18. Chirality plays important roles in radiopharmaceuticals

    International Nuclear Information System (INIS)

    Shen Yumei

    2006-01-01

    The paper introduces the basic concept of chirality, target specific selectivity and their relationship in radiopharmaceuticals. If the ligands labeled by radionuclides have chiral center, the enantiomers must be separated, or the target specific selectivity will not be good. Chirality is one of the most important factors which must be considered in the study of the structure-activity relationship of radiopharmaceuticals. (authors)

  19. Graphene–cyclodextrin–cytochrome c layered assembly with improved electron transfer rate and high supramolecular recognition capability

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Cheng-Bin; Guo, Cong-Cong; Jiang, Dan; Tang, Qian, E-mail: qiantang@swu.edu.cn; Liu, Chang-Hua; Ma, Xue-Bing

    2014-06-01

    This study aimed to develop a new graphene-based layered assembly, named graphene–cyclodextrin–cytochrome c with improved electron transfer rate. This assembly has combined high conductivity of graphene nanosheets (GNs), selectively binding properties and electronegativity of cyclodextrins (CDs), as well as electropositivity of cytochrome c (Cyt c). This assembly can also mimic the confined environments of the intermembrane space of mitochondria. A β-cyclodextrin (β-CD) functionalized GN (GN–CD) assembly was initially prepared by a simple wet-chemical strategy, i.e., in situ thermal reduction of graphene oxide with hydrazine hydrate in the presence of β-CD. Cyt c was then intercalated to the GN–CD assembly to form a layered self-assembled structure, GN–CD–Cyt c, through electrostatic interaction. Compared with GNs and GN–CD, GN–CD–Cyt c assembly displayed improved electron transfer rate and high supramolecular recognition capability toward six probe molecules. - Highlights: • A new tertiary layered assembly named GN–CD–Cyt c was prepared. • Compared with GNs and GN–CD, GN–CD–Cyt c shows improved electron transfer rate. • GN–CD–Cyt c displays high supramolecular recognition capability.

  20. Graphene–cyclodextrin–cytochrome c layered assembly with improved electron transfer rate and high supramolecular recognition capability

    International Nuclear Information System (INIS)

    Gong, Cheng-Bin; Guo, Cong-Cong; Jiang, Dan; Tang, Qian; Liu, Chang-Hua; Ma, Xue-Bing

    2014-01-01

    This study aimed to develop a new graphene-based layered assembly, named graphene–cyclodextrin–cytochrome c with improved electron transfer rate. This assembly has combined high conductivity of graphene nanosheets (GNs), selectively binding properties and electronegativity of cyclodextrins (CDs), as well as electropositivity of cytochrome c (Cyt c). This assembly can also mimic the confined environments of the intermembrane space of mitochondria. A β-cyclodextrin (β-CD) functionalized GN (GN–CD) assembly was initially prepared by a simple wet-chemical strategy, i.e., in situ thermal reduction of graphene oxide with hydrazine hydrate in the presence of β-CD. Cyt c was then intercalated to the GN–CD assembly to form a layered self-assembled structure, GN–CD–Cyt c, through electrostatic interaction. Compared with GNs and GN–CD, GN–CD–Cyt c assembly displayed improved electron transfer rate and high supramolecular recognition capability toward six probe molecules. - Highlights: • A new tertiary layered assembly named GN–CD–Cyt c was prepared. • Compared with GNs and GN–CD, GN–CD–Cyt c shows improved electron transfer rate. • GN–CD–Cyt c displays high supramolecular recognition capability

  1. Pions and the chiral bag

    International Nuclear Information System (INIS)

    Rho, M.

    1982-01-01

    As an aid to discussing the structure of nucleons and nuclei conceptual framework, heuristic arguments are presented which indicate that a hadron can be considered as a bag consisting of two different phases. The chiral structure of the phase outside the bag is discussed in terms of effective field theories and it is shown to what extent experiments in nuclei can constrain the structure of such theories. Results thus obtained are then combined to set up a set of equations for the bag structure of u and d hadrons, incorporating asymptotic freedom in the phase inside of the bag confinement of quarks and gluons by boundary conditions and spontaneously broken chiral symmetry in the outside. This set of equations which represent a chirally invariant generalization of the M.I.T. bag model is then solved. (U.K.)

  2. Fusion rules of chiral algebras

    International Nuclear Information System (INIS)

    Gaberdiel, M.

    1994-01-01

    Recently we showed that for the case of the WZW and the minimal models fusion can be understood as a certain ring-like tensor product of the symmetry algebra. In this paper we generalize this analysis to arbitrary chiral algebras. We define the tensor product of conformal field theory in the general case and prove that it is associative and symmetric up to equivalence. We also determine explicitly the action of the chiral algebra on this tensor product. In the second part of the paper we demonstrate that this framework provides a powerful tool for calculating restrictions for the fusion rules of chiral algebras. We exhibit this for the case of the W 3 algebra and the N=1 and N=2 NS superconformal algebras. (orig.)

  3. Physics of chiral symmetry breaking

    International Nuclear Information System (INIS)

    Shuryak, E.V.

    1991-01-01

    This subsection of the 'Modeling QCD' Workshop has included five talks. E. Shuryak spoke on 'Recent Progress in Understanding Chiral Symmetry Breaking'; below it is split into two parts: (i) a mini-review of the field and (ii) a brief presentation of the status of the theory of interacting instantons. The next sections correspond to the following talks: (iii) K. Goeke et al., 'Chiral Restoration and Medium Corrections to Nucleon in the NJL Model'; (iv) M. Takizawa and K. Kubodera, 'Study of Meson Properties and Quark Condensates in the NJL Model with Instanton Effects'; (v) G. Klein and A. G. Williams, 'Dynamical Chiral Symmetry Breaking in Dual QCD'; and (vi) R. D. Ball, 'Skyrmions and Baryons.' (orig.)

  4. Chirality and gravitational parity violation.

    Science.gov (United States)

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented. © 2015 Wiley Periodicals, Inc.

  5. Chiral interaction and biomolecular evolution

    International Nuclear Information System (INIS)

    Gilat, G.

    1992-01-01

    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)

  6. High affinity antigen recognition of the dual specific variants of herceptin is entropy-driven in spite of structural plasticity.

    Directory of Open Access Journals (Sweden)

    Jenny Bostrom

    Full Text Available The antigen-binding site of Herceptin, an anti-human Epidermal Growth Factor Receptor 2 (HER2 antibody, was engineered to add a second specificity toward Vascular Endothelial Growth Factor (VEGF to create a high affinity two-in-one antibody bH1. Crystal structures of bH1 in complex with either antigen showed that, in comparison to Herceptin, this antibody exhibited greater conformational variability, also called "structural plasticity". Here, we analyzed the biophysical and thermodynamic properties of the dual specific variants of Herceptin to understand how a single antibody binds two unrelated protein antigens. We showed that while bH1 and the affinity-improved bH1-44, in particular, maintained many properties of Herceptin including binding affinity, kinetics and the use of residues for antigen recognition, they differed in the binding thermodynamics. The interactions of bH1 and its variants with both antigens were characterized by large favorable entropy changes whereas the Herceptin/HER2 interaction involved a large favorable enthalpy change. By dissecting the total entropy change and the energy barrier for dual interaction, we determined that the significant structural plasticity of the bH1 antibodies demanded by the dual specificity did not translate into the expected increase of entropic penalty relative to Herceptin. Clearly, dual antigen recognition of the Herceptin variants involves divergent antibody conformations of nearly equivalent energetic states. Hence, increasing the structural plasticity of an antigen-binding site without increasing the entropic cost may play a role for antibodies to evolve multi-specificity. Our report represents the first comprehensive biophysical analysis of a high affinity dual specific antibody binding two unrelated protein antigens, furthering our understanding of the thermodynamics that drive the vast antigen recognition capacity of the antibody repertoire.

  7. Chiral soliton models for baryons

    International Nuclear Information System (INIS)

    Weigel, H.

    2008-01-01

    This concise research monograph introduces and reviews the concept of chiral soliton models for baryons. In these models, baryons emerge as (topological) defects of the chiral field. The many applications shed light on a number of baryon properties, ranging from static properties via nucleon resonances and deep inelastic scattering to even heavy ion collisions. As far as possible, the theoretical investigations are confronted with experiment. Conceived to bridge the gap between advanced graduate textbooks and the research literature, this volume also features a number of appendices to help nonspecialist readers to follow in more detail some of the calculations in the main text. (orig.)

  8. Surface defects and chiral algebras

    Energy Technology Data Exchange (ETDEWEB)

    Córdova, Clay [School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, NJ 08540 (United States); Gaiotto, Davide [Perimeter Institute for Theoretical Physics,31 Caroline St N, Waterloo, ON N2L 2Y5 (Canada); Shao, Shu-Heng [School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, NJ 08540 (United States)

    2017-05-26

    We investigate superconformal surface defects in four-dimensional N=2 superconformal theories. Each such defect gives rise to a module of the associated chiral algebra and the surface defect Schur index is the character of this module. Various natural chiral algebra operations such as Drinfeld-Sokolov reduction and spectral flow can be interpreted as constructions involving four-dimensional surface defects. We compute the index of these defects in the free hypermultiplet theory and Argyres-Douglas theories, using both infrared techniques involving BPS states, as well as renormalization group flows onto Higgs branches. In each case we find perfect agreement with the predicted characters.

  9. 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...

  10. Chiral symmetry on the lattice

    International Nuclear Information System (INIS)

    Creutz, M.

    1994-11-01

    The author reviews some of the difficulties associated with chiral symmetry in the context of a lattice regulator. The author discusses the structure of Wilson Fermions when the hopping parameter is in the vicinity of its critical value. Here one flavor contrasts sharply with the case of more, where a residual chiral symmetry survives anomalies. The author briefly discusses the surface mode approach, the use of mirror Fermions to cancel anomalies, and finally speculates on the problems with lattice versions of the standard model

  11. Structure functions in the chiral bag model

    International Nuclear Information System (INIS)

    Sanjose, V.; Vento, V.; Centro Mixto CSIC/Valencia Univ., Valencia

    1989-01-01

    We calculate the structure functions of an isoscalar nuclear target for the deep inelastic scattering by leptons in an extended version of the chiral bag model which incorporates the qanti q structure of the pions in the cloud. Bjorken scaling and Regge behavior are satisfied. The model calculation reproduces the low-x behavior of the data but fails to explain the medium- to large-x behavior. Evolution of the quark structure functions seem inevitable to attempt a connection between the low-energy models and the high-energy behavior of quantum chromodynamics. (orig.)

  12. Structure functions in the chiral bag model

    Energy Technology Data Exchange (ETDEWEB)

    Sanjose, V.; Vento, V.

    1989-07-13

    We calculate the structure functions of an isoscalar nuclear target for the deep inelastic scattering by leptons in an extended version of the chiral bag model which incorporates the qanti q structure of the pions in the cloud. Bjorken scaling and Regge behavior are satisfied. The model calculation reproduces the low-x behavior of the data but fails to explain the medium- to large-x behavior. Evolution of the quark structure functions seem inevitable to attempt a connection between the low-energy models and the high-energy behavior of quantum chromodynamics. (orig.).

  13. Dynamic perception: Some theorems about the possibility of parallel pattern recognition with an application to high energy physics

    International Nuclear Information System (INIS)

    Perrone, A.; Basti, G.

    1994-01-01

    In the context of M. Minsky's and S. Papert's theorems on the impossibility of evaluating simple linear predicates by parallel architectures the authors want to show how these limitations can be avoided by introducing a generalized input-dependent preprocessing technique that does not suppose any a-priori knowledge of input like in classical input filtering procedures. This technique can be formalized in a very general way and can be also deduced by metamathematical arguments. A further development of the same technique can be applied at level of learning procedure to introduce in such a way the complete notion of open-quotes dynamic perceptronclose quotes. From the experimental standpoint, they show two applications of the open-quotes dynamic perceptronclose quotes in particle track recognition in high-energy accelerators. Firstly, they show the amazing improvement of performances that can be obtained in a perceptron architecture with classical learning by adding their open-quotes dynamicclose quotes pre-processing technique, already introduced last year in another paper presented at this Conference. Secondly, they show the results of this technique extended also at the level of learning procedure always applied to the problem of particle track recognition. This work is a part of open-quotes Feniceclose quotes international collaboration supported by INFN (National Institute for Nuclear Physics) devoted to the study of the time-like electromagnetic form factor of neutrons obtained by electron-positron high energy collisions in ADONE (Frascati, Rome) storage ring

  14. Chiral gauge theory on AdS domain wall

    International Nuclear Information System (INIS)

    Shirman, Yuri

    2005-01-01

    We describe a realization of chiral gauge theories based on the domaim wall fermion construction implemented on an interval in five dimensional AdS spacetime. At semi-classical level deconstructed description of the theory is given in terms of 4-dimensional Minkowski slices supporting chiral zero modes at the ends. Energy scales warp down along the fifth dimension. When the theory is augmented by 4-dimensional neutral Majorana spinors together with the Higgs mechanism at the low energy end, we can arrange for a theory where the lightest gauge boson mode as well as chiral zero mode at the high energy end are parametrically lighter than other states. Triangle anomalies and instanton effects are expected to make gauge bosons heavy if the resulting effective theory is anomalous. Due to the strong coupling effects at the quantum level, full non-perturbative calculation will be necessary to validate this construction

  15. 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.

  16. Distinguishing standard model extensions using monotop chirality at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Allahverdi, Rouzbeh [Department of Physics and Astronomy, University of New Mexico,Albuquerque, NM 87131 (United States); Dalchenko, Mykhailo; Dutta, Bhaskar [Department of Physics and Astronomy,Mitchell Institute for Fundamental Physics and Astronomy, Texas A& M University,College Station, TX 77843-4242 (United States); Flórez, Andrés [Departamento de Física, Universidad de los Andes,Bogotá, Carrera 1 18A-10, Bloque IP (Colombia); Gao, Yu [Department of Physics and Astronomy,Mitchell Institute for Fundamental Physics and Astronomy, Texas A& M University,College Station, TX 77843-4242 (United States); Kamon, Teruki [Department of Physics and Astronomy,Mitchell Institute for Fundamental Physics and Astronomy, Texas A& M University,College Station, TX 77843-4242 (United States); Department of Physics, Kyungpook National University,Daegu 702-701 (Korea, Republic of); Kolev, Nikolay [Department of Physics, University of Regina,SK, S4S 0A2 (Canada); Mueller, Ryan [Department of Physics and Astronomy,Mitchell Institute for Fundamental Physics and Astronomy, Texas A& M University,College Station, TX 77843-4242 (United States); Segura, Manuel [Departamento de Física, Universidad de los Andes,Bogotá, Carrera 1 18A-10, Bloque IP (Colombia)

    2016-12-13

    We present two minimal extensions of the standard model, each giving rise to baryogenesis. They include heavy color-triplet scalars interacting with a light Majorana fermion that can be the dark matter (DM) candidate. The electroweak charges of the new scalars govern their couplings to quarks of different chirality, which leads to different collider signals. These models predict monotop events at the LHC and the energy spectrum of decay products of highly polarized top quarks can be used to establish the chiral nature of the interactions involving the heavy scalars and the DM. Detailed simulation of signal and standard model background events is performed, showing that top quark chirality can be distinguished in hadronic and leptonic decays of the top quarks.

  17. Chirality-selected phase behaviour in ionic polypeptide complexes

    Science.gov (United States)

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

    2015-01-01

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

  18. Reversible optical transcription of supramolecular chirality into molecular chirality

    NARCIS (Netherlands)

    Jong, Jaap J.D. de; Lucas, Linda N.; Kellogg, Richard M.; Esch, Jan H. van; Feringa, Bernard

    2004-01-01

    In nature, key molecular processes such as communication, replication, and enzyme catalysis all rely on a delicate balance between molecular and supramolecular chirality. Here we report the design, synthesis, and operation of a reversible, photoresponsive, self-assembling molecular system in which

  19. Neuronal growth on L- and D-cysteine self-assembled monolayers reveals neuronal chiral sensitivity.

    Science.gov (United States)

    Baranes, Koby; Moshe, Hagay; Alon, Noa; Schwartz, Shmulik; Shefi, Orit

    2014-05-21

    Studying the interaction between neuronal cells and chiral molecules is fundamental for the design of novel biomaterials and drugs. Chirality influences all biological processes that involve intermolecular interaction. One common method used to study cellular interactions with different enantiomeric targets is the use of chiral surfaces. Based on previous studies that demonstrated the importance of cysteine in the nervous system, we studied the effect of L- and D-cysteine on single neuronal growth. L-Cysteine, which normally functions as a neuromodulator or a neuroprotective antioxidant, causes damage at elevated levels, which may occur post trauma. In this study, we grew adult neurons in culture enriched with L- and D-cysteine as free compounds or as self-assembled monolayers of chiral surfaces and examined the effect on the neuronal morphology and adhesion. Notably, we have found that exposure to the L-cysteine enantiomer inhibited, and even prevented, neuronal attachment more severely than exposure to the D-cysteine enantiomer. Atop the L-cysteine surfaces, neuronal growth was reduced and degenerated. Since the cysteine molecules were attached to the surface via the thiol groups, the neuronal membrane was exposed to the molecular chiral site. Thus, our results have demonstrated high neuronal chiral sensitivity, revealing chiral surfaces as indirect regulators of neuronal cells and providing a reference for studying chiral drugs.

  20. Oscillation damping of chiral string loops

    International Nuclear Information System (INIS)

    Babichev, Eugeny; Dokuchaev, Vyacheslav

    2002-01-01

    Chiral cosmic string loops tend to the stationary (vorton) configuration due to energy loss into gravitational and electromagnetic radiation. We describe the asymptotic behavior of near stationary chiral loops and their fading to vortons. General limits on the gravitational and electromagnetic energy losses by near stationary chiral loops are found. For these loops we estimate the oscillation damping time. We present solvable examples of gravitational radiation energy loss by some chiral loop configurations. The analytical dependence of string energy with time is found in the case of the chiral ring with small amplitude radial oscillations

  1. Lanthanide tris(β-diketonates) as useful probes for chirality determination of biological amino alcohols in vibrational circular dichroism: ligand to ligand chirality transfer in lanthanide coordination sphere.

    Science.gov (United States)

    Miyake, Hiroyuki; Terada, Keiko; Tsukube, Hiroshi

    2014-06-01

    A series of lanthanide tris(β-diketonates) functioned as useful chirality probes in the vibrational circular dichroism (VCD) characterization of biological amino alcohols. Various chiral amino alcohols induced intense VCD signals upon ternary complexation with racemic lanthanide tris(β-diketonates). The VCD signals observed around 1500 cm(-1) (β-diketonate IR absorption region) correlated well with the stereochemistry and enantiomeric purity of the targeted amino alcohol, while the corresponding monoalcohol, monoamine, and diol substrates induced very weak VCD signals. The high-coordination number and dynamic property of the lanthanide complex offer an effective chirality VCD probing of biological substrates. © 2014 Wiley Periodicals, Inc.

  2. No chiral truncation of quantum log gravity?

    Science.gov (United States)

    Andrade, Tomás; Marolf, Donald

    2010-03-01

    At the classical level, chiral gravity may be constructed as a consistent truncation of a larger theory called log gravity by requiring that left-moving charges vanish. In turn, log gravity is the limit of topologically massive gravity (TMG) at a special value of the coupling (the chiral point). We study the situation at the level of linearized quantum fields, focussing on a unitary quantization. While the TMG Hilbert space is continuous at the chiral point, the left-moving Virasoro generators become ill-defined and cannot be used to define a chiral truncation. In a sense, the left-moving asymptotic symmetries are spontaneously broken at the chiral point. In contrast, in a non-unitary quantization of TMG, both the Hilbert space and charges are continuous at the chiral point and define a unitary theory of chiral gravity at the linearized level.

  3. High Accuracy Human Activity Recognition Based on Sparse Locality Preserving Projections.

    Science.gov (United States)

    Zhu, Xiangbin; Qiu, Huiling

    2016-01-01

    Human activity recognition(HAR) from the temporal streams of sensory data has been applied to many fields, such as healthcare services, intelligent environments and cyber security. However, the classification accuracy of most existed methods is not enough in some applications, especially for healthcare services. In order to improving accuracy, it is necessary to develop a novel method which will take full account of the intrinsic sequential characteristics for time-series sensory data. Moreover, each human activity may has correlated feature relationship at different levels. Therefore, in this paper, we propose a three-stage continuous hidden Markov model (TSCHMM) approach to recognize human activities. The proposed method contains coarse, fine and accurate classification. The feature reduction is an important step in classification processing. In this paper, sparse locality preserving projections (SpLPP) is exploited to determine the optimal feature subsets for accurate classification of the stationary-activity data. It can extract more discriminative activities features from the sensor data compared with locality preserving projections. Furthermore, all of the gyro-based features are used for accurate classification of the moving data. Compared with other methods, our method uses significantly less number of features, and the over-all accuracy has been obviously improved.

  4. High Accuracy Human Activity Recognition Based on Sparse Locality Preserving Projections.

    Directory of Open Access Journals (Sweden)

    Xiangbin Zhu

    Full Text Available Human activity recognition(HAR from the temporal streams of sensory data has been applied to many fields, such as healthcare services, intelligent environments and cyber security. However, the classification accuracy of most existed methods is not enough in some applications, especially for healthcare services. In order to improving accuracy, it is necessary to develop a novel method which will take full account of the intrinsic sequential characteristics for time-series sensory data. Moreover, each human activity may has correlated feature relationship at different levels. Therefore, in this paper, we propose a three-stage continuous hidden Markov model (TSCHMM approach to recognize human activities. The proposed method contains coarse, fine and accurate classification. The feature reduction is an important step in classification processing. In this paper, sparse locality preserving projections (SpLPP is exploited to determine the optimal feature subsets for accurate classification of the stationary-activity data. It can extract more discriminative activities features from the sensor data compared with locality preserving projections. Furthermore, all of the gyro-based features are used for accurate classification of the moving data. Compared with other methods, our method uses significantly less number of features, and the over-all accuracy has been obviously improved.

  5. Recognition of anesthetic barbiturates by a protein binding site: a high resolution structural analysis.

    Directory of Open Access Journals (Sweden)

    Simon Oakley

    Full Text Available Barbiturates potentiate GABA actions at the GABA(A receptor and act as central nervous system depressants that can induce effects ranging from sedation to general anesthesia. No structural information has been available about how barbiturates are recognized by their protein targets. For this reason, we tested whether these drugs were able to bind specifically to horse spleen apoferritin, a model protein that has previously been shown to bind many anesthetic agents with affinities that are closely correlated with anesthetic potency. Thiopental, pentobarbital, and phenobarbital were all found to bind to apoferritin with affinities ranging from 10-500 µM, approximately matching the concentrations required to produce anesthetic and GABAergic responses. X-ray crystal structures were determined for the complexes of apoferritin with thiopental and pentobarbital at resolutions of 1.9 and 2.0 Å, respectively. These structures reveal that the barbiturates bind to a cavity in the apoferritin shell that also binds haloalkanes, halogenated ethers, and propofol. Unlike these other general anesthetics, however, which rely entirely upon van der Waals interactions and the hydrophobic effect for recognition, the barbiturates are recognized in the apoferritin site using a mixture of both polar and nonpolar interactions. These results suggest that any protein binding site that is able to recognize and respond to the chemically and structurally diverse set of compounds used as general anesthetics is likely to include a versatile mixture of both polar and hydrophobic elements.

  6. A New Twist on Chirality

    NARCIS (Netherlands)

    Feringa, Bernard

    2001-01-01

    One of the great mysteries in science is the homochirality (single handedness) of the essential molecules of life. Natural sugars are almost exclusively right-handed; natural amino acids are almost exclusively left-handed. Current life forms could not exist without the uniform chirality of these

  7. Instantons and chiral symmetry breaking

    International Nuclear Information System (INIS)

    Carneiro, C.E.I.; McDougall, N.A.

    1984-01-01

    A detailed investigation of chiral symmetry breaking due to instanton dynamics is carried out, within the framework of the dilute gas approximation, for quarks in both the fundamental and adjoint representations of SU(2). The momentum dependence of the dynamical mass is found to be very similar in each representation. (orig.)

  8. Instantons and chiral symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, C.E.I.; McDougall, N.A. (Oxford Univ. (UK). Dept. of Theoretical Physics)

    1984-10-22

    A detailed investigation of chiral symmetry breaking due to instanton dynamics is carried out, within the framework of the dilute gas approximation, for quarks in both the fundamental and adjoint representations of SU(2). The momentum dependence of the dynamical mass is found to be very similar in each representation.

  9. Status of chiral perturbation theory

    International Nuclear Information System (INIS)

    Ecker, G.

    1996-10-01

    A survey is made of semileptonic and nonleptonic kaon decays in the framework of chiral perturbation theory. The emphasis is on what has been done rather than how it was done. The theoretical predictions are compared with available experimental results. (author)

  10. Principles of chiral perturbation theory

    International Nuclear Information System (INIS)

    Leutwyler, H.

    1995-01-01

    An elementary discussion of the main concepts used in chiral perturbation theory is given in textbooks and a more detailed picture of the applications may be obtained from the reviews. Concerning the foundations of the method, the literature is comparatively scarce. So, I will concentrate on the basic concepts and explain why the method works. (author)

  11. Chiral symmetry in perturbative QCD

    International Nuclear Information System (INIS)

    Trueman, T.L.

    1979-04-01

    The chiral symmetry of quantum chromodynamics with massless quarks is unbroken in perturbation theory. Dimensional regularization is used. The ratio of the vector and axial vector renormalization constante is shown to be independent of the renormalization mass. The general results are explicitly verified to fourth order in g, the QCD coupling constant

  12. Descendants of the Chiral Anomaly

    OpenAIRE

    Jackiw, R.

    2000-01-01

    Chern-Simons terms are well-known descendants of chiral anomalies, when the latter are presented as total derivatives. Here I explain that also Chern-Simons terms, when defined on a 3-manifold, may be expressed as total derivatives.

  13. Cross-recognition of a pit viper (Crotalinae) polyspecific antivenom explored through high-density peptide microarray epitope mapping

    DEFF Research Database (Denmark)

    Engmark, Mikael; Lomonte, Bruno; Gutiérrez, José María

    2017-01-01

    Snakebite antivenom is a 120 years old invention based on polyclonal mixtures of antibodies purified from the blood of hyper-immunized animals. Knowledge on antibody recognition sites (epitopes) on snake venom proteins is limited, but may be used to provide molecular level explanations...... for antivenom cross-reactivity. In turn, this may help guide antivenom development by elucidating immunological biases in existing antivenoms. In this study, we have identified and characterized linear elements of B-cell epitopes from 870 pit viper venom protein sequences by employing a high......-throughput methodology based on custom designed high-density peptide microarrays. By combining data on antibody-peptide interactions with multiple sequence alignments of homologous toxin sequences and protein modelling, we have determined linear elements of antibody binding sites for snake venom metalloproteases (SVMPs...

  14. Innate recognition of bacteria in human milk is mediated by a milk-derived highly expressed pattern recognition receptor, soluble CD14.

    OpenAIRE

    Lab?ta, MO; Vidal, K; Nores, JE; Arias, M; Vita, N; Morgan, BP; Guillemot, JC; Loyaux, D; Ferrara, P; Schmid, D; Affolter, M; Borysiewicz, LK; Donnet-Hughes, A; Schiffrin, EJ

    2000-01-01

    Little is known about innate immunity to bacteria after birth in the hitherto sterile fetal intestine. Breast-feeding has long been associated with a lower incidence of gastrointestinal infections and inflammatory and allergic diseases. We found in human breast milk a 48-kD polypeptide, which we confirmed by mass spectrometry and sequencing to be a soluble form of the bacterial pattern recognition receptor CD14 (sCD14). Milk sCD14 (m-sCD14) concentrations were up to 20-fold higher than serum ...

  15. Innate Recognition of Bacteria in Human Milk Is Mediated by a Milk-Derived Highly Expressed Pattern Recognition Receptor, Soluble Cd14

    OpenAIRE

    Labéta, Mario O.; Vidal, Karine; Nores, Julia E. Rey; Arias, Mauricio; Vita, Natalio; Morgan, B. Paul; Guillemot, Jean Claude; Loyaux, Denis; Ferrara, Pascual; Schmid, Daniel; Affolter, Michael; Borysiewicz, Leszek K.; Donnet-Hughes, Anne; Schiffrin, Eduardo J.

    2000-01-01

    Little is known about innate immunity to bacteria after birth in the hitherto sterile fetal intestine. Breast-feeding has long been associated with a lower incidence of gastrointestinal infections and inflammatory and allergic diseases. We found in human breast milk a 48-kD polypeptide, which we confirmed by mass spectrometry and sequencing to be a soluble form of the bacterial pattern recognition receptor CD14 (sCD14). Milk sCD14 (m-sCD14) concentrations were up to 20-fold higher than serum ...

  16. Nuclear chiral dynamics and thermodynamics

    Science.gov (United States)

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

    2013-11-01

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

  17. Molecular Design of a Chiral Brønsted Acid with Two Different Acidic Sites: Regio-, Diastereo-, and Enantioselective Hetero-Diels-Alder Reaction of Azopyridinecarboxylate with Amidodienes Catalyzed by Chiral Carboxylic Acid-Monophosphoric Acid.

    Science.gov (United States)

    Momiyama, Norie; Tabuse, Hideaki; Noda, Hirofumi; Yamanaka, Masahiro; Fujinami, Takeshi; Yamanishi, Katsunori; Izumiseki, Atsuto; Funayama, Kosuke; Egawa, Fuyuki; Okada, Shino; Adachi, Hiroaki; Terada, Masahiro

    2016-09-07

    A chiral Brønsted acid containing two different acidic sites, chiral carboxylic acid-monophosphoric acid 1a, was designed to be a new and effective concept in catalytic asymmetric hetero-Diels-Alder reactions of azopyridinecarboxylate with amidodienes. The multipoint hydrogen-bonding interactions among the carboxylic acid, monophosphoric acid, azopyridinecarboxylate, and amidodiene achieved high catalytic and chiral efficiency, producing substituted 1,2,3,6-tetrahydropyridazines with excellent stereocontrol in a single step. This constitutes the first example of regio-, diastereo-, and enantioselective azo-hetero-Diels-Alder reactions by chiral Brønsted acid catalysis.

  18. Near-field circular polarization probed by chiral polyfluorene

    NARCIS (Netherlands)

    Savoini, M.; Biagioni, P.; Lakhwani, G.; Meskers, S.C.J.; Duò, L.; Finazzi, M.

    2009-01-01

    We demonstrate that a high degree of circular polarization can be delivered to the near field (NF) of an aperture at the apex of hollow-pyramid probes for scanning optical microscopy. This result is achieved by analyzing the dichroic properties of an annealed thin polymer film containing a chiral

  19. [Prosopagnosia and facial expression recognition].

    Science.gov (United States)

    Koyama, Shinichi

    2014-04-01

    This paper reviews clinical neuropsychological studies that have indicated that the recognition of a person's identity and the recognition of facial expressions are processed by different cortical and subcortical areas of the brain. The fusiform gyrus, especially the right fusiform gyrus, plays an important role in the recognition of identity. The superior temporal sulcus, amygdala, and medial frontal cortex play important roles in facial-expression recognition. Both facial recognition and facial-expression recognition are highly intellectual processes that involve several regions of the brain.

  20. Empirical Equation Based Chirality (n, m Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Directory of Open Access Journals (Sweden)

    Md Shamsul Arefin

    2012-12-01

    Full Text Available This work presents a technique for the chirality (n, m assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n, m with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot.

  1. Empirical Equation Based Chirality (n, m) Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Science.gov (United States)

    Arefin, Md Shamsul

    2012-01-01

    This work presents a technique for the chirality (n, m) assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n− m) with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m) of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot. PMID:28348319

  2. Molecularly imprinted polyaniline-ferrocene-sulfonic acid-Carbon dots modified pencil graphite electrodes for chiral selective sensing of D-Ascorbic acid and L-Ascorbic acid: A clinical biomarker for preeclampsia

    International Nuclear Information System (INIS)

    Pandey, Indu; Jha, Shashank Shekhar

    2015-01-01

    Highlights: • Pencil graphite electrode was non-covalently functionalized by C-dots. • Electrochemically synthesized ferrocene-sulfonic acid doped PANI film was used as chiral recognition element. • Electrochemical chiral sensing of L-ascorbic acid and D-ascorbic acid was carried out. • L-ascorbic acid determination was done in aqueous, biological and pharmaceutical samples at nM level. - Abstract: A simple and novel method is proposed for chiral separation of L-ascorbic acid and D-ascorbic acid in human cerebrospinal fluids and blood plasma samples. Electro-polymerized molecularly imprinted poly-aniline ferrocenesulfonic acid-C-dots modified pencil graphite electrodes was successfully applied for separation and quantification of D-/L-ascorbic acid in aqueous and some biological samples. Parameters, important to control the performance of the electrochemical sensor were investigated and optimized, including the effects of pH, monomer- template ratios, electropolymerization cycles and scan rates. The molecularly imprinted film exhibited a high chiral selectivity and sensitivity towards D-ascorbic acid and L-ascorbic acid respectively. The surface morphologies and electrochemical properties of the proposed sensor were characterized by scanning electron microscopy, cyclic voltammetry, difference pulse voltammetry, chrono-amperometry and electrochemical impedance spectroscopy. L-ascorbic acid selective sensor shows excellent selectivity towards the L-ascorbic acid in comparison to D- ascorbic acid vice versa for D- ascorbic acid selective sensor. Under optimal conditions the linear range of the calibration curve for L- ascorbic acid and D- ascorbic acid was 6.0–165.0 nM and 6.0–155.0 nM, with the detection limit of 0.001 nM and 0.002 nM. Chiral detection of L-ascorbic acid was successfully carried out in pharmaceuticals and human plasma samples (pregnant women and non pregnant women) via proposed sensor with good selectivity and sensitivity.

  3. New high-performance liquid chromatography method for the determination of (R)-warfarin and (S)-warfarin using chiral separation on a glycopeptide-based stationary phase.

    Science.gov (United States)

    Malakova, Jana; Pavek, Petr; Svecova, Lucie; Jokesova, Iveta; Zivny, Pavel; Palicka, Vladimir

    2009-10-01

    Warfarin is a well-known anticoagulant agent that occurs in two enantiomers, (R)-(+)-warfarin and (S)-(-)-warfarin. A new liquid chromatography method for the determination of both enantiomers was developed, validated and applied in in vitro studies with the aim of evaluating the accumulation of (R)-warfarin and (S)-warfarin in the hepatoma HepG2 cell line. OptiMEM cell cultivation medium samples and cellular lysates were purified using Waters Oasis MAX extraction cartridges. The chiral separation of warfarin and the internal standard p-chlorowarfarin enantiomers was performed on an Astec Chirobiotic V2 column at a flow rate of 1.2mL/min. The mobile phase was composed of 31% acetonitrile, 5% of methanol and 64% of ammonium acetate buffer (10mmol/L, pH 4.1). The enantiomers were quantified using a fluorescence detector (lambda(excit)=320nm, lambda(emiss)=415nm). The limit of detection was found to be 0.121micromol/L of (S)-warfarin and 0.109micromol/L of (R)-warfarin. The range of applicability and linearity was estimated from 0.25 to 100micromol/L. The precision ranged from 1.3% to 12.2% of the relative standard deviation, and the accuracy reached acceptable values from 95.5% to 108.4%. The new bioanalytical method confirmed the same accumulation of (R)-warfarin and (S)-warfarin in the hepatoma HepG2 cell line.

  4. Rhodium-catalyzed Asymmetric Hydrogenation of α-Dehydroamino Ketones: A General Approach to Chiral α-amino Ketones.

    Science.gov (United States)

    Gao, Wenchao; Wang, Qingli; Xie, Yun; Lv, Hui; Zhang, Xumu

    2016-01-01

    Rhodium/DuanPhos-catalyzed asymmetric hydrogenation of aliphatic α-dehydroamino ketones has been achieved and afforded chiral α-amino ketones in high yields and excellent enantioselectives (up to 99 % ee), which could be reduced further to chiral β-amino alcohols by LiAlH(tBuO)3 with good yields. This protocol provides a readily accessible route for the synthesis of chiral α-amino ketones and chiral β-amino alcohols. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Two-dimensional field theory description of a disoriented chiral condensate

    International Nuclear Information System (INIS)

    Kogan, I.I.

    1993-01-01

    We consider the effective (1+1)-dimensional chiral theory describing fluctuations of the order parameter of the disoriented chiral condensate (DCC) which can be formed in the central rapidity region in relativistic nucleus-nucleus or nucleon-nucleon collisions at high energy. Using (1+1)-dimensional reduction of QCD at high energies and assuming spin polarization of the DDC one can find the Wess-Zumino-Novikov-Witten model at the level k=3 as the effective chiral theory for the one-dimensional DDC. Some possible phenomenological consequences are briefly discussed

  6. High School Equivalency Assessment and Recognition in the United States: An Eyewitness Account

    Science.gov (United States)

    McLendon, Lennox

    2017-01-01

    This chapter on high school equivalency describes recent events involved in updating the adult education high school equivalency assessment services and the entrance of additional assessments into the field.

  7. The kinetics of chirality assignment in catalytic single-walled carbon nanotube growth and the routes towards selective growth.

    Science.gov (United States)

    Xu, Ziwei; Qiu, Lu; Ding, Feng

    2018-03-21

    Depending on its specific structure, or so-called chirality, a single-walled carbon nanotube (SWCNT) can be either a conductor or a semiconductor. This feature ensures great potential for building ∼1 nm sized electronics if chirality-selected SWCNTs could be achieved. However, due to the limited understanding of the growth mechanism of SWCNTs, reliable methods for chirality-selected SWCNTs are still pending. Here we present a theoretical model on the chirality assignment and control of SWCNTs during the catalytic growth. This study reveals that the chirality of a SWCNT is determined by the kinetic incorporation of pentagons, especially the last (6 th ) one, during the nucleation stage. Our analysis showed that the chirality of a SWCNT is randomly assigned on a liquid or liquid-like catalyst surface, and two routes of synthesizing chirality-selected SWCNTs, which are verified by recent experimental achievements, are demonstrated. They are (i) by using high melting point crystalline catalysts, such as Ta, W, Re, Os, or their alloys, and (ii) by frequently changing the chirality of SWCNTs during their growth. This study paves the way for achieving chirality-selective SWCNT growth for high performance SWCNT based electronics.

  8. Timoshenko beam model for chiral materials

    Science.gov (United States)

    Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

    2018-06-01

    Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

  9. Photoexcitation circular dichroism in chiral molecules

    Science.gov (United States)

    Beaulieu, S.; Comby, A.; Descamps, D.; Fabre, B.; Garcia, G. A.; Géneaux, R.; Harvey, A. G.; Légaré, F.; Mašín, Z.; Nahon, L.; Ordonez, A. F.; Petit, S.; Pons, B.; Mairesse, Y.; Smirnova, O.; Blanchet, V.

    2018-05-01

    Chiral effects appear in a wide variety of natural phenomena and are of fundamental importance in science, from particle physics to metamaterials. The standard technique of chiral discrimination—photoabsorption circular dichroism—relies on the magnetic properties of a chiral medium and yields an extremely weak chiral response. Here, we propose and demonstrate an orders of magnitude more sensitive type of circular dichroism in neutral molecules: photoexcitation circular dichroism. This technique does not rely on weak magnetic effects, but takes advantage of the coherent helical motion of bound electrons excited by ultrashort circularly polarized light. It results in an ultrafast chiral response and the efficient excitation of a macroscopic chiral density in an initially isotropic ensemble of randomly oriented chiral molecules. We probe this excitation using linearly polarized laser pulses, without the aid of further chiral interactions. Our time-resolved study of vibronic chiral dynamics opens a way to the efficient initiation, control and monitoring of chiral chemical change in neutral molecules at the level of electrons.

  10. A 3-D open-framework material with intrinsic chiral topology used as a stationary phase in gas chromatography.

    Science.gov (United States)

    Xie, Sheng-Ming; Zhang, Xin-Huan; Zhang, Ze-Jun; Zhang, Mei; Jia, Jia; Yuan, Li-Ming

    2013-04-01

    Compared with liquid chromatography and capillary electrophoresis, the diversity of gas chromatography chiral stationary phases is rather limited. Here, we report the fabrication of Co(D-Cam)1/2(bdc)1/2(tmdpy) (D-Cam = D-camphoric acid; bdc = 1,4-benzenedicarboxylate; tmdpy = 4,4'-trimethylenedipyridine)-coated open tubular columns for high-resolution gas chromatographic separation of compounds. The Co(D-Cam)1/2(bdc)1/2(tmdpy) compound possesses a 3-D framework containing enantiopure building blocks embedded in intrinsically chiral topological nets. In this study, two fused-silica open tubular columns with different inner diameters and lengths, including column A (30 m × 530 μm i.d.) and column B (2 m × 75 μm i.d.), were prepared by a dynamic coating method using Co-(D-Cam)1/2(bdc)1/2(tmdpy) as the stationary phase. The chromatographic properties of the two columns were investigated using n-dodecane as the test compound at 120 °C. The number of theoretical plates (plates/m) of the two metal-organic framework columns was 1,450 and 3,100, respectively. The separation properties were evaluated using racemates, isomers, alkanes, alcohols, and Grob's test mixture. The limit of detection and limit of quantification were found to be 0.125 and 0.417 ng for citronellal enantiomers, respectively. Repeatability (n = 6) showed lower than 0.25 % relative standard deviation (RSD) for retention times and lower than 2.2 % RSD for corrected peak areas. The experimental results showed that the stationary phase has excellent selectivity and also possesses good recognition ability toward these organic compounds, especially chiral compounds.

  11. Speech Recognition

    Directory of Open Access Journals (Sweden)

    Adrian Morariu

    2009-01-01

    Full Text Available This paper presents a method of speech recognition by pattern recognition techniques. Learning consists in determining the unique characteristics of a word (cepstral coefficients by eliminating those characteristics that are different from one word to another. For learning and recognition, the system will build a dictionary of words by determining the characteristics of each word to be used in the recognition. Determining the characteristics of an audio signal consists in the following steps: noise removal, sampling it, applying Hamming window, switching to frequency domain through Fourier transform, calculating the magnitude spectrum, filtering data, determining cepstral coefficients.

  12. Chiral heat wave and mixing of magnetic, vortical and heat waves in chiral media

    International Nuclear Information System (INIS)

    Chernodub, M.N.

    2016-01-01

    We show that a hot rotating fluid of relativistic chiral fermions possesses a new gapless collective mode associated with coherent propagation of energy density and chiral density waves along the axis of rotation. This mode, 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. The coupling of the Chiral Magnetic and Chiral Vortical Waves is also demonstrated. 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.

  13. Static and dynamical anomalies caused by chiral soliton lattice in molecular-based chiral magnets

    International Nuclear Information System (INIS)

    Kishine, Jun-ichiro; Inoue, Katsuya; Kikuchi, Koichi

    2007-01-01

    Interplay of crystallographic chirality and magnetic chirality has been of great interest in both chemist's and physicist's viewpoints. Crystals belonging to chiral space groups are eligible to stabilize macroscopic chiral magnetic order. This class of magnetic order is described by the chiral XY model, where the transverse magnetic field perpendicular to the chiral axis causes the chiral soliton lattice (CSL) formation. As a clear evidence of the chiral magnetic order, the temperature dependence of the transverse magnetization exhibits sharp cusp just below the mean field ferrimagnetic transition temperature, indicating the formation of the CSL. In addition to the static anomaly, we expect the CSL formation also causes dynamical anomalies such as induction of the spin supercurrent

  14. QCD and the chiral critical point

    International Nuclear Information System (INIS)

    Gavin, S.; Gocksch, A.; Pisarski, R.D.

    1994-01-01

    As an extension of QCD, consider a theory with ''2+1'' flavors, where the current quark masses are held in a fixed ratio as the overall scale of the quark masses is varied. At nonzero temperature and baryon density it is expected that in the chiral limit the chiral phase transition is of first order. Increasing the quark mass from zero, the chiral transition becomes more weakly first order, and can end in a chiral critical point. We show that the only massless field at the chiral critical point is a σ meson, with the universality class that of the Ising model. Present day lattice simulations indicate that QCD is (relatively) near to the chiral critical point

  15. 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.

  16. Nucleon parton distributions in chiral perturbation theory

    International Nuclear Information System (INIS)

    Moiseeva, Alena

    2013-01-01

    Properties of the chiral expansion of nucleon light-cone operators have been studied. In the framework of the chiral perturbation theory we have demonstrated that convergency of the chiral expansion of nucleon parton distributions strongly depends on the value of the variable x. Three regions in x with essentially different analytical properties of the resulting chiral expansion for parton distributions were found. For each of the regions we have elaborated special power counting rules corresponding to the partial resummation of the chiral series. The nonlocal effective operators for the vector and the axial nucleon parton distributions have been constructed at the zeroth and the first chiral order. Using the derived nonlocal operators and the derived power counting rules we have obtained the second order expressions for the nucleon GPDs H(x,ξ,Δ 2 ), H(x,ξ,Δ 2 ),E(x,ξ,Δ 2 ) valid in the region x>or similar a 2 χ .

  17. Bootstrapping N=2 chiral correlators

    Science.gov (United States)

    Lemos, Madalena; Liendo, Pedro

    2016-01-01

    We apply the numerical bootstrap program to chiral operators in four-dimensional N=2 SCFTs. In the first part of this work we study four-point functions in which all fields have the same conformal dimension. We give special emphasis to bootstrapping a specific theory: the simplest Argyres-Douglas fixed point with no flavor symmetry. In the second part we generalize our setup and consider correlators of fields with unequal dimension. This is an example of a mixed correlator and allows us to probe new regions in the parameter space of N=2 SCFTs. In particular, our results put constraints on relations in the Coulomb branch chiral ring and on the curvature of the Zamolodchikov metric.

  18. 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.

  19. Bootstrapping N=2 chiral correlators

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Madalena [DESY Hamburg, Theory Group,Notkestrasse 85, D-22607 Hamburg (Germany); Liendo, Pedro [IMIP, Humboldt-Universität zu Berlin, IRIS Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany)

    2016-01-07

    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.

  20. Quantum formulation for nanoscale optical and material chirality: symmetry issues, space and time parity, and observables

    Science.gov (United States)

    Andrews, D. L.

    2018-03-01

    To properly represent the interplay and coupling of optical and material chirality at the photon-molecule or photon-nanoparticle level invites a recognition of quantum facets in the fundamental aspects and mechanisms of light-matter interaction. It is therefore appropriate to cast theory in a general quantum form, one that is applicable to both linear and nonlinear optics as well as various forms of chiroptical interaction including chiral optomechanics. Such a framework, fully accounting for both radiation and matter in quantum terms, facilitates the scrutiny and identification of key issues concerning spatial and temporal parity, scale, dissipation and measurement. Furthermore it fully provides for describing the interactions of structured or twisted light beams with a vortex character, and it leads to the complete identification of symmetry conditions for materials to provide for chiral discrimination. Quantum considerations also lend a distinctive perspective to the very different senses in which other aspects of chirality are recognized in metamaterials. Duly attending to the symmetry principles governing allowed or disallowed forms of chiral discrimination supports an objective appraisal of the experimental possibilities and developing applications.

  1. Stimulus recognition occurs under high perceptual load: Evidence from correlated flankers.

    Science.gov (United States)

    Cosman, Joshua D; Mordkoff, J Toby; Vecera, Shaun P

    2016-12-01

    A dominant account of selective attention, perceptual load theory, proposes that when attentional resources are exhausted, task-irrelevant information receives little attention and goes unrecognized. However, the flanker effect-typically used to assay stimulus identification-requires an arbitrary mapping between a stimulus and a response. We looked for failures of flanker identification by using a more-sensitive measure that does not require arbitrary stimulus-response mappings: the correlated flankers effect. We found that flanking items that were task-irrelevant but that correlated with target identity produced a correlated flanker effect. Participants were faster on trials in which the irrelevant flanker had previously correlated with the target than when it did not. Of importance, this correlated flanker effect appeared regardless of perceptual load, occurring even in high-load displays that should have abolished flanker identification. Findings from a standard flanker task replicated the basic perceptual load effect, with flankers not affecting response times under high perceptual load. Our results indicate that task-irrelevant information can be processed to a high level (identification), even under high perceptual load. This challenges a strong account of high perceptual load effects that hypothesizes complete failures of stimulus identification under high perceptual load. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  2. Chiral Tunnelling in Twisted Graphene Bilayer

    OpenAIRE

    He, Wen-Yu; Chu, Zhao-Dong; He, Lin

    2013-01-01

    The perfect transmission in graphene monolayer and the perfect reflection in Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in twisted graphene bilayer shows adjustable probability of chiral tunnelling for normal incidence: they can be changed fr...

  3. Enantioselective Biotransformation of Chiral Persistent Organic Pollutants.

    Science.gov (United States)

    Zhang, Ying; Ye, Jing; Liu, Min

    2017-01-01

    Enantiomers of chiral compounds commonly undergo enantioselective transformation in most biologically mediated processes. As chiral persistent organic pollutants (POPs) are extensively distributed in the environment, differences between enantiomers in biotransformation should be carefully considered to obtain exact enrichment and specific health risks. This review provides an overview of in vivo biotransformation of chiral POPs currently indicated in the Stockholm Convention and their chiral metabolites. Peer-reviewed journal articles focused on the research question were thoroughly searched. A set of inclusion and exclusion criteria were developed to identify relevant studies. We mainly compared the results from different animal models under controlled laboratory conditions to show the difference between enantiomers in terms of distinct transformation potential. Interactions with enzymes involved in enantioselective biotransformation, especially cytochrome P450 (CYP), were discussed. Further research areas regarding this issue were proposed. Limited evidence for a few POPs has been found in 30 studies. Enantioselective biotransformation of α-hexachlorocyclohexane (α-HCH), chlordane, dichlorodiphenyltrichloroethane (DDT), heptachlor, hexabromocyclododecane (HBCD), polychlorinated biphenyls (PCBs), and toxaphene, has been investigated using laboratory mammal, fish, bird, and worm models. Tissue and excreta distributions, as well as bioaccumulation and elimination kinetics after administration of racemate and pure enantiomers, have been analyzed in these studies. Changes in enantiomeric fractions have been considered as an indicator of enantioselective biotransformation of chiral POPs in most studies. Results of different laboratory animal models revealed that chiral POP biotransformation is seriously affected by chirality. Pronounced results of species-, tissue-, gender-, and individual-dependent differences are observed in in vivo biotransformation of chiral POPs

  4. Supersymmetry and the chiral Schwinger model

    International Nuclear Information System (INIS)

    Amorim, R.; Das, A.

    1998-01-01

    We have constructed the N= (1) /(2) supersymmetric general Abelian model with asymmetric chiral couplings. This leads to a N= (1) /(2) supersymmetrization of the Schwinger model. We show that the supersymmetric general model is plagued with problems of infrared divergence. Only the supersymmetric chiral Schwinger model is free from such problems and is dynamically equivalent to the chiral Schwinger model because of the peculiar structure of the N= (1) /(2) multiplets. copyright 1998 The American Physical Society

  5. 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....

  6. Higher derivative regularization and chiral anomaly

    International Nuclear Information System (INIS)

    Nagahama, Yoshinori.

    1985-02-01

    A higher derivative regularization which automatically leads to the consistent chiral anomaly is analyzed in detail. It explicitly breaks all the local gauge symmetry but preserves global chiral symmetry and leads to the chirally symmetric consistent anomaly. This regularization thus clarifies the physics content contained in the consistent anomaly. We also briefly comment on the application of this higher derivative regularization to massless QED. (author)

  7. Chiral anomaly, bosonization and fractional charge

    International Nuclear Information System (INIS)

    Mignaco, J.A.; Rego Monteiro, M.A. do.

    1984-01-01

    A method to evaluate the Jacobian of chiral rotations, regulating determinants through the proper time method and using Seeley's asymptotic expansion is presented. With this method the chiral anomaly ofr ν=4,6 dimensions is computed easily, bosonization of some massless two-dimensional models is discussed and the problem of charge fractionization is handled. Besides, the general validity of Fujikawa's approach to regulate the Jacobian of chiral rotations with non-hermitean operators is commented. (Author) [pt

  8. The chirality operators for Heisenberg spin systems

    International Nuclear Information System (INIS)

    Subrahmanyam, V.

    1994-01-01

    The ground state of closed Heisenberg spin chains with an odd number of sites has a chiral degeneracy, in addition to a two-fold Kramers degeneracy. A non-zero chirality implies that the spins are not coplanar, and is a measure of handedness. The chirality operator, which can be treated as a spin-1/2 operator, is explicitly constructed in terms of the spin operators, and is given as commutator of permutation operators. (author). 3 refs

  9. Chiral anomaly, bosonization, and fractional charge

    International Nuclear Information System (INIS)

    Mignaco, J.A.; Monteiro, M.A.R.

    1985-01-01

    We present a method to evaluate the Jacobian of chiral rotations, regulating determinants through the proper-time method and using Seeley's asymptotic expansion. With this method we compute easily the chiral anomaly for ν = 4,6 dimensions, discuss bosonization of some massless two-dimensional models, and handle the problem of charge fractionization. In addition, we comment on the general validity of Fujikawa's approach to regulate the Jacobian of chiral rotations with non-Hermitian operators

  10. Broadband reflection of polymer-stabilized chiral nematic liquid crystals induced by a chiral azobenzene compound.

    Science.gov (United States)

    Chen, Xingwu; Wang, Ling; Chen, Yinjie; Li, Chenyue; Hou, Guoyan; Liu, Xin; Zhang, Xiaoguang; He, Wanli; Yang, Huai

    2014-01-21

    A chiral nematic liquid crystal-photopolymerizable monomer-chiral azobenzene compound composite was prepared and then polymerized under UV irradiation. The reflection wavelength of the composite can be extended to cover the 1000-2400 nm range and also be adjusted to the visible light region by controlling the concentration of chiral compounds.

  11. Staggered chiral random matrix theory

    International Nuclear Information System (INIS)

    Osborn, James C.

    2011-01-01

    We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.

  12. Homogenization of resonant chiral metamaterials

    OpenAIRE

    Andryieuski, Andrei; Menzel, Christoph; Rockstuhl, Carsten; Malureanu, Radu; Lederer, Falk; Lavrinenko, Andrei

    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 a critical density exists above which increasing coupling between neighboring meta-atoms prevails a reasonable homogenization. On the contrary, a dilution in excess will induce features reminiscent to pho...

  13. Chiral Lagrangians and the SSC

    International Nuclear Information System (INIS)

    Dawson, S.

    1991-09-01

    In the event that the SSC does not observe any resonances such as a Higgs boson or a techni-rho meson, we would like to know if the SSC can still discover something about the nature of the electroweak symmetry breaking. We will use chiral Lagrangian techniques to address this question and analyze their utility for studying events containing W and Z gauge bosons at the SSC. 20 refs., 4 figs

  14. Is there chirality in atomic nuclei?

    International Nuclear Information System (INIS)

    Meng Jie

    2009-01-01

    Static chiral symmetries are common in nature, for example, the macroscopic spirals of snail shells, the microscopic handedness of certain molecules, and human hands. The concept of chirality in atomic nuclei was first proposed in 1997, and since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Recent theoretical and experimental progress in the verification of chirality in atomic nuclei will be reviewed, together with a discussion of the problems that await to be solved in the future. (authors)

  15. 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.

  16. Self-inductance of chiral conducting nanotubes

    International Nuclear Information System (INIS)

    Miyamoto, Yoshiyuki; Rubio, Angel; Louie, Steven G.; Cohen, Marvin L.

    1998-01-01

    Chiral conductivity in nanotubes has recently been predicted theoretically. The realization and application of chiral conducting nanotubes can be of great interest from both fundamental and technological viewpoints. These chiral currents, if they are realized, can be detected by measuring the self-inductance. We have treated Maxwell's equations for chiral conducting nanotubes (nanocoils) and find that the self-inductance and the resistivity of nanocoils should depend on the frequency of the alternating current even when the capacitance of the nanocoils is not taken into account. This is in contrast to elementary treatment of ordinary coils. This fact is useful to distinguish nanocoils by electrical measurements

  17. Emotion recognition through static faces and moving bodies: a comparison between typically developed adults and individuals with high level of autistic traits.

    Science.gov (United States)

    Actis-Grosso, Rossana; Bossi, Francesco; Ricciardelli, Paola

    2015-01-01

    We investigated whether the type of stimulus (pictures of static faces vs. body motion) contributes differently to the recognition of emotions. The performance (accuracy and response times) of 25 Low Autistic Traits (LAT group) young adults (21 males) and 20 young adults (16 males) with either High Autistic Traits or with High Functioning Autism Spectrum Disorder (HAT group) was compared in the recognition of four emotions (Happiness, Anger, Fear, and Sadness) either shown in static faces or conveyed by moving body patch-light displays (PLDs). Overall, HAT individuals were as accurate as LAT ones in perceiving emotions both with faces and with PLDs. Moreover, they correctly described non-emotional actions depicted by PLDs, indicating that they perceived the motion conveyed by the PLDs per se. For LAT participants, happiness proved to be the easiest emotion to be recognized: in line with previous studies we found a happy face advantage for faces, which for the first time was also found for bodies (happy body advantage). Furthermore, LAT participants recognized sadness better by static faces and fear by PLDs. This advantage for motion kinematics in the recognition of fear was not present in HAT participants, suggesting that (i) emotion recognition is not generally impaired in HAT individuals, (ii) the cues exploited for emotion recognition by LAT and HAT groups are not always the same. These findings are discussed against the background of emotional processing in typically and atypically developed individuals.

  18. Emotion recognition through static faces and moving bodies: a comparison between typically-developed adults and individuals with high level of autistic traits

    Directory of Open Access Journals (Sweden)

    Rossana eActis-Grosso

    2015-10-01

    Full Text Available We investigated whether the type of stimulus (pictures of static faces vs. body motion contributes differently to the recognition of emotions. The performance (accuracy and response times of 25 Low Autistic Traits (LAT group young adults (21 males and 20 young adults (16 males with either High Autistic Traits (HAT group or with High Functioning Autism Spectrum Disorder was compared in the recognition of four emotions (Happiness, Anger, Fear and Sadness either shown in static faces or conveyed by moving bodies (patch-light displays, PLDs. Overall, HAT individuals were as accurate as LAT ones in perceiving emotions both with faces and with PLDs. Moreover, they correctly described non-emotional actions depicted by PLDs, indicating that they perceived the motion conveyed by the PLDs per se. For LAT participants, happiness proved to be the easiest emotion to be recognized: in line with previous studies we found a happy face advantage for faces, which for the first time was also found for bodies (happy body advantage. Furthermore, LAT participants recognized sadness better by static faces and fear by PLDs. This advantage for motion kinematics in the recognition of fear was not present in HAT participants, suggesting that i emotion recognition is not generally impaired in HAT individuals, ii the cues exploited for emotion recognition by LAT and HAT groups are not always the same. These findings are discussed against the background of emotional processing in typically and atypically developed individuals.

  19. Chiral four-membered cyclic nitrones; asymmetric induction in the (4+2)-cycloaddition reaction of chiral ynamines and nitroalkenes

    NARCIS (Netherlands)

    van Elburg, P.A.; Honig, G.W.N.; Reinhoudt, David

    1987-01-01

    Chiral four-membered cyclic nitrones were synthesized by the asymmetric (4+2)-cycloaddition of nitroalkenes 1 and chiral ynamines 2. The subsequent stereoselective addition of nucleophiles to these nitrones enabled the synthesis of chiral N-hydroxyazetidines.

  20. A novel stable 3D luminescent uranyl complex for highly efficient and sensitive recognition of Ru3+ and biomolecules

    Science.gov (United States)

    Tian, Hong-Hong; Chen, Liang-Ting; Zhang, Rong-Lan; Zhao, Jian-She; Liu, Chi-Yang; Weng, Ng Seik

    2018-02-01

    A novel highly stable 3D luminescent uranyl coordination polymer, namely {[UO2(L)]·DMA}n (1), was assembled with uranyl salt and a glycine-derivative ligand [6-(carboxymethyl-amino)-4-oxo-4,5-dihydro-[1,3,5]triazin-2-ylamino]-acetic acid (H2L) under solvothermal reaction. Besides, It was found that complex 1 possesses excellent luminescent properties, particularly the efficient selectivity and sensitivity in the recognition of Ru3+, biomacromolecule bovine serum albumin (BSA), biological small molecules dopamine (DA), ascorbic acid (AA) and uric acid (UA) in the water solution based on a "turn-off" mechanism. Accordingly, the luminescent explorations also demonstrated that complex 1 could be acted as an efficient luminescent probe with high quenching efficiency and low detection limit for selectively detecting Ru3+ and biomolecules (DA, AA, UA and BSA). It was noted that the framework structure of complex 1 still remains highly stable after quenching, which was verified by powder X-ray diffraction (PXRD).

  1. Two-chiral-component microemulsion electrokinetic chromatography-chiral surfactant and chiral oil: part 1. dibutyl tartrate.

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-06-01

    The first simultaneous use of a chiral surfactant and a chiral oil for microemulsion EKC (MEEKC) is reported. Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2-hexanol (1.65% v/v), and dibutyl tartrate (D, L, or racemic, 1.23% v/v) were examined as chiral pseudostationary phases (PSPs) for the separation of six pairs of pharmaceutical enantiomers: pseudoephedrine, ephedrine, N-methyl ephedrine, metoprolol, synephrine, and atenolol. Subtle differences were observed for three chromatographic figures of merit (alpha(enant), alpha(meth), k) among the chiral microemulsions; a moderate difference was observed for efficiency (N) and elution range. Dual-chirality microemulsions provided both the largest and smallest enantioselectivities, due to small positive and negative synergies between the chiral microemulsion components. For the ephedrine family of compounds, dual-chiral microemulsions with surfactant and oil in opposite stereochemical configurations provided higher enantioselectivities than the single-chiral component microemulsion (RXX), whereas dual-chiral microemulsions with surfactant and oil in the same stereochemical configurations provided lower enantioselectivities than RXX. Slight to moderate enantioselective synergies were confirmed using a thermodynamic model. Efficiencies observed with microemulsions comprised of racemic dibutyl tartrate or dibutyl-D-tartrate were significantly higher than those obtained with dibutyl-L-tartrate, with an average difference in plate count of about 25 000. Finally, one two-chiral-component microemulsion (RXS) provided significantly better resolution than the remaining one- and two-chiral-component microemulsions for the ephedrine-based compounds, but only slightly better or equivalent resolution for non-ephedrine compounds.

  2. Do Adults with High Functioning Autism or Asperger Syndrome Differ in Empathy and Emotion Recognition?

    Science.gov (United States)

    Montgomery, Charlotte B.; Allison, Carrie; Lai, Meng-Chuan; Cassidy, Sarah; Langdon, Peter E.; Baron-Cohen, Simon

    2016-01-01

    The present study examined whether adults with high functioning autism (HFA) showed greater difficulties in (1) their self-reported ability to empathise with others and/or (2) their ability to read mental states in others' eyes than adults with Asperger syndrome (AS). The Empathy Quotient (EQ) and "Reading the Mind in the Eyes" Test…

  3. A disoriented chiral condensate search at the Fermilab Tevatron

    International Nuclear Information System (INIS)

    Convery, M.E.

    1997-05-01

    MiniMax (Fermilab T-864) was a small test/experiment at the Tevatron designed to search for disoriented chiral condensates (DCC) in the forward direction. Relativistic quantum field theory treats the vacuum as a medium, with bulk properties characterized by long-range order parameters. This has led to suggestions that regions of open-quotes disoriented vacuumclose quotes might be formed in high-energy collision processes. In particular, the approximate chiral symmetry of QCD could lead to regions of vacuum which have chiral order parameters disoriented to directions which have non-zero isospin, i.e. disoriented chiral condensates. A signature of DCC is the resulting distribution of the fraction of produced pions which are neutral. The MiniMax detector at the C0 collision region of the Tevatron was a telescope of 24 multi-wire proportional chambers (MWPC's) with a lead converter behind the eighth MWPC, allowing the detection of charged particles and photon conversions in an acceptance approximately a circle of radius 0.6 in pseudorapidity-azimuthal-angle space, centered on pseudorapidity η ∼ 4. An electromagnetic calorimeter was located behind the MWPC telescope, and hadronic calorimeters and scintillator were located in the upstream anti-proton direction to tag diffractive events

  4. Chiral separation and enantioselective degradation of vinclozolin in soils.

    Science.gov (United States)

    Liu, Hui; Liu, Donghui; Shen, Zhigang; Sun, Mingjing; Zhou, Zhiqiang; Wang, Peng

    2014-03-01

    Vinclozolin is a chiral fungicide with potential environmental problems. The chiral separation of the enantiomers and enantioselective degradation in soil were investigated in this work. The enantiomers were separated by high-performance liquid chromatography (HPLC) on Chiralpak IA, IB, and AZ-H chiral columns under normal phase and the influence of the mobile phase composition on the separation was also studied. Complete resolutions were obtained on all three chiral columns under optimized conditions with the same elution order of (+)/(-). The residual analysis of the enantiomers in soil was conducted using accelerate solvent extraction followed by HPLC determination. The recoveries of the enantiomers ranged from 85.7-105.7% with relative standard deviation (SD) of 0.12-3.83%, and the limit of detection (LOD) of the method was 0.013 µg/g. The results showed that the degradations of vinclozolin enantiomers in the soils followed first-order kinetics. Preferential degradation of the (-)-enantiomer was observed only in one soil with the largest |ES| value of 0.047, and no obvious enantioselective degradation was observed in other soils. It was found that the persistence of vinclozolin in soil was related to pH values based on the half-lives. The two enantiomers disappeared about 8 times faster in basic soils than that in neutral or acidic soils. © 2014 Wiley Periodicals, Inc.

  5. Chiral ferrocenes in asymmetric catalysis: synthesis and applications

    National Research Council Canada - National Science Library

    Dai, Li-Xin; Hou, Xue-Long

    2010-01-01

    .... It provides a thorough overview of the synthesis and characterization of different types of chiral ferrocene ligands, their application to various catalytic asymmetric reactions, and versatile chiral...

  6. Rapid and Accurate Machine Learning Recognition of High Performing Metal Organic Frameworks for CO2 Capture.

    Science.gov (United States)

    Fernandez, Michael; Boyd, Peter G; Daff, Thomas D; Aghaji, Mohammad Zein; Woo, Tom K

    2014-09-04

    In this work, we have developed quantitative structure-property relationship (QSPR) models using advanced machine learning algorithms that can rapidly and accurately recognize high-performing metal organic framework (MOF) materials for CO2 capture. More specifically, QSPR classifiers have been developed that can, in a fraction of a section, identify candidate MOFs with enhanced CO2 adsorption capacity (>1 mmol/g at 0.15 bar and >4 mmol/g at 1 bar). The models were tested on a large set of 292 050 MOFs that were not part of the training set. The QSPR classifier could recover 945 of the top 1000 MOFs in the test set while flagging only 10% of the whole library for compute intensive screening. Thus, using the machine learning classifiers as part of a high-throughput screening protocol would result in an order of magnitude reduction in compute time and allow intractably large structure libraries and search spaces to be screened.

  7. Fuzzy method of recognition of high molecular substances in evidence-based biology

    Science.gov (United States)

    Olevskyi, V. I.; Smetanin, V. T.; Olevska, Yu. B.

    2017-10-01

    Nowadays modern requirements to achieving reliable results along with high quality of researches put mathematical analysis methods of results at the forefront. Because of this, evidence-based methods of processing experimental data have become increasingly popular in the biological sciences and medicine. Their basis is meta-analysis, a method of quantitative generalization of a large number of randomized trails contributing to a same special problem, which are often contradictory and performed by different authors. It allows identifying the most important trends and quantitative indicators of the data, verification of advanced hypotheses and discovering new effects in the population genotype. The existing methods of recognizing high molecular substances by gel electrophoresis of proteins under denaturing conditions are based on approximate methods for comparing the contrast of electrophoregrams with a standard solution of known substances. We propose a fuzzy method for modeling experimental data to increase the accuracy and validity of the findings of the detection of new proteins.

  8. Effect of physical workload and modality of information presentation on pattern recognition and navigation task performance by high-fit young males.

    Science.gov (United States)

    Zahabi, Maryam; Zhang, Wenjuan; Pankok, Carl; Lau, Mei Ying; Shirley, James; Kaber, David

    2017-11-01

    Many occupations require both physical exertion and cognitive task performance. Knowledge of any interaction between physical demands and modalities of cognitive task information presentation can provide a basis for optimising performance. This study examined the effect of physical exertion and modality of information presentation on pattern recognition and navigation-related information processing. Results indicated males of equivalent high fitness, between the ages of 18 and 34, rely more on visual cues vs auditory or haptic for pattern recognition when exertion level is high. We found that navigation response time was shorter under low and medium exertion levels as compared to high intensity. Navigation accuracy was lower under high level exertion compared to medium and low levels. In general, findings indicated that use of the haptic modality for cognitive task cueing decreased accuracy in pattern recognition responses. Practitioner Summary: An examination was conducted on the effect of physical exertion and information presentation modality in pattern recognition and navigation. In occupations requiring information presentation to workers, who are simultaneously performing a physical task, the visual modality appears most effective under high level exertion while haptic cueing degrades performance.

  9. Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

    Energy Technology Data Exchange (ETDEWEB)

    Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

    2016-10-01

    Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained beta-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer

  10. Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

    Science.gov (United States)

    Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

    2016-10-01

    Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained β-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer

  11. Chiral behavior of K →π l ν decay form factors in lattice QCD with exact chiral symmetry

    Science.gov (United States)

    Aoki, S.; Cossu, G.; Feng, X.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Onogi, T.; Jlqcd Collaboration

    2017-08-01

    We calculate the form factors of the K →π l ν semileptonic decays in three-flavor lattice QCD and study their chiral behavior as a function of the momentum transfer and the Nambu-Goldstone boson masses. Chiral symmetry is exactly preserved by using the overlap quark action, which enables us to directly compare the lattice data with chiral perturbation theory (ChPT). We generate gauge ensembles at a lattice spacing of 0.11 fm with four pion masses covering 290-540 MeV and a strange quark mass ms close to its physical value. By using the all-to-all quark propagator, we calculate the vector and scalar form factors with high precision. Their dependence on ms and the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields. We compare the results for the semileptonic form factors with ChPT at next-to-next-to-leading order in detail. While many low-energy constants appear at this order, we make use of our data of the light meson electromagnetic form factors in order to control the chiral extrapolation. We determine the normalization of the form factors as f+(0 )=0.9636 (36 )(-35+57) and observe reasonable agreement of their shape with experiment.

  12. Graphene-cyclodextrin-cytochrome c layered assembly with improved electron transfer rate and high supramolecular recognition capability.

    Science.gov (United States)

    Gong, Cheng-Bin; Guo, Cong-Cong; Jiang, Dan; Tang, Qian; Liu, Chang-Hua; Ma, Xue-Bing

    2014-06-01

    This study aimed to develop a new graphene-based layered assembly, named graphene-cyclodextrin-cytochrome c with improved electron transfer rate. This assembly has combined high conductivity of graphene nanosheets (GNs), selectively binding properties and electronegativity of cyclodextrins (CDs), as well as electropositivity of cytochrome c (Cyt c). This assembly can also mimic the confined environments of the intermembrane space of mitochondria. A β-cyclodextrin (β-CD) functionalized GN (GN-CD) assembly was initially prepared by a simple wet-chemical strategy, i.e., in situ thermal reduction of graphene oxide with hydrazine hydrate in the presence of β-CD. Cyt c was then intercalated to the GN-CD assembly to form a layered self-assembled structure, GN-CD-Cyt c, through electrostatic interaction. Compared with GNs and GN-CD, GN-CD-Cyt c assembly displayed improved electron transfer rate and high supramolecular recognition capability toward six probe molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space.

    Science.gov (United States)

    Ma, Wei Ji; Zhou, Xiang; Ross, Lars A; Foxe, John J; Parra, Lucas C

    2009-01-01

    Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness), one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

  14. Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space.

    Directory of Open Access Journals (Sweden)

    Wei Ji Ma

    Full Text Available Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness, one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

  15. Chiral DOTA chelators as an improved platform for biomedical imaging and therapy applications.

    Science.gov (United States)

    Dai, Lixiong; Jones, Chloe M; Chan, Wesley Ting Kwok; Pham, Tiffany A; Ling, Xiaoxi; Gale, Eric M; Rotile, Nicholas J; Tai, William Chi-Shing; Anderson, Carolyn J; Caravan, Peter; Law, Ga-Lai

    2018-02-27

    Despite established clinical utilisation, there is an increasing need for safer, more inert gadolinium-based contrast agents, and for chelators that react rapidly with radiometals. Here we report the syntheses of a series of chiral DOTA chelators and their corresponding metal complexes and reveal properties that transcend the parent DOTA compound. We incorporated symmetrical chiral substituents around the tetraaza ring, imparting enhanced rigidity to the DOTA cavity, enabling control over the range of stereoisomers of the lanthanide complexes. The Gd chiral DOTA complexes are shown to be orders of magnitude more inert to Gd release than [GdDOTA] - . These compounds also exhibit very-fast water exchange rates in an optimal range for high field imaging. Radiolabeling studies with (Cu-64/Lu-177) also demonstrate faster labelling properties. These chiral DOTA chelators are alternative general platforms for the development of stable, high relaxivity contrast agents, and for radiometal complexes used for imaging and/or therapy.

  16. Task Phase Recognition for Highly Mobile Workers in Large Building Complexes

    DEFF Research Database (Denmark)

    Stisen, Allan; Mathisen, Andreas; Krogh, Søren

    2016-01-01

    requirements on the accuracy of the indoor positioning, and thus come with low deployment and maintenance effort in real-world settings. We evaluated the proposed methods in a large hospital complex, where the highly mobile workers were recruited among the non-clinical workforce. The evaluation is based......-scale indoor work environments, namely from a WiFi infrastructure providing coarse grained indoor positioning, from inertial sensors in the workers’ mobile phones, and from a task management system yielding information about the scheduled tasks’ start and end locations. The methods presented have low...... on manually labelled real-world data collected over 4 days of regular work life of the mobile workforce. The collected data yields 83 tasks in total involving 8 different orderlies from a major university hospital with a building area of 160, 000 m2. The results show that the proposed methods can distinguish...

  17. A rhodium(III) complex for high-affinity DNA base-pair mismatch recognition

    Science.gov (United States)

    Junicke, Henrik; Hart, Jonathan R.; Kisko, Jennifer; Glebov, Oleg; Kirsch, Ilan R.; Barton, Jacqueline K.

    2003-01-01

    A rhodium(III) complex, rac-[Rh(bpy)2phzi]3+ (bpy, 2,2′-bipyridine; phzi, benzo[a]phenazine-5,6-quinone diimine) has been designed as a sterically demanding intercalator targeted to destabilized mismatched sites in double-helical DNA. The complex is readily synthesized by condensation of the phenazine quinone with the corresponding diammine complex. Upon photoactivation, the complex promotes direct strand scission at single-base mismatch sites within the DNA duplex. As with the parent mismatch-specific reagent, [Rh(bpy)2(chrysi)]3+ [chrysene-5,6-quinone diimine (chrysi)], mismatch selectivity depends on the helix destabilization associated with mispairing. Unlike the parent chrysi complex, the phzi analogue binds and cleaves with high affinity and efficiency. The specific binding constants for CA, CC, and CT mismatches within a 31-mer oligonucleotide duplex are 0.3, 1, and 6 × 107 M−1, respectively; site-specific photocleavage is evident at nanomolar concentrations. Moreover, the specificity, defined as the ratio in binding affinities for mispaired vs. well paired sites, is maintained. The increase in affinity is attributed to greater stability in the mismatched site associated with stacking by the heterocyclic aromatic ligand. The high-affinity complex is also applied in the differential cleavage of DNA obtained from cell lines deficient in mismatch repair vs. those proficient in mismatch repair. Agreement is found between photocleavage by the mismatch-specific probes and deficiency in mismatch repair. This mismatch-specific targeting, therefore, offers a potential strategy for new chemotherapeutic design. PMID:12610209

  18. Thermoelectric figure of merit of chiral carbon nanotube

    International Nuclear Information System (INIS)

    Mensah, N.G.; Nkrumah-Buandoh, G.K.; Mensah, S.Y.; Allotey, F.K.A.; Twum, A.K.

    2005-09-01

    We have investigated the thermoelectrical properties of chiral carbon nanotube and numerically evaluated the figure of merit. We observed that the properties are highly anisotropic and depend on the geometric chiral angle (GCA) θ h , temperature and the overlapping integrals (exchange energy) for the jumps along the tubular axis Δ z and the base helix Δ s . The thermopower α exhibited giant values with the peak occurring between 100 K and 150 K. The electron thermal conductivity showed unusually high value with the peaks shifting towards high temperature. We attribute the high peak values to electron-phonon interactions. Finally we noted that by changing the Δ s and Δ z it is possible to get a figure of merit greater than 1. (author)

  19. Characteristics of chiral anomaly in view of various applications

    Science.gov (United States)

    Fujikawa, Kazuo

    2018-01-01

    In view of the recent applications of chiral anomaly to various fields beyond particle physics, we discuss some basic aspects of chiral anomaly which may help deepen our understanding of chiral anomaly in particle physics also. It is first shown that Berry's phase (and its generalization) for the Weyl model H =vFσ →.p →(t ) assumes a monopole form at the exact adiabatic limit but deviates from it off the adiabatic limit and vanishes in the high frequency limit of the Fourier transform of p →(t ) for bounded |p →(t )|. An effective action, which is consistent with the nonadiabatic limit of Berry's phase, combined with the Bjorken-Johnson-Low prescription, gives normal equal-time space-time commutators and no chiral anomaly. In contrast, an effective action with a monopole at the origin of the momentum space, which describes Berry's phase in the precise adiabatic limit but fails off the adiabatic limit, gives anomalous space-time commutators and a covariant anomaly to the gauge current. We regard this anomaly as an artifact of the postulated monopole and not a consequence of Berry's phase. As for the recent application of the chiral anomaly to the description of effective Weyl fermions in condensed matter and nuclear physics, which is closely related to the formulation of lattice chiral fermions, we point out that the chiral anomaly for each species doubler separately vanishes for a finite lattice spacing, contrary to the common assumption. Instead, a general form of pair creation associated with the spectral flow for the Dirac sea with finite depth takes place. This view is supported by the Ginsparg-Wilson fermion, which defines a single Weyl fermion without doublers on the lattice and gives a well-defined index (anomaly) even for a finite lattice spacing. A different use of anomaly in analogy to the partially conserved axial-vector current is also mentioned and could lead to an effect without fermion number nonconservation.

  20. Alcohol Recognition by Flexible, Transparent and Highly Sensitive Graphene-Based Thin-Film Sensors

    KAUST Repository

    Xu, Xuezhu

    2017-06-22

    Chemical sensors detect a variety of chemicals across numerous fields, such as automobile, aerospace, safety, indoor air quality, environmental control, food, industrial production and medicine. We successfully assemble an alcohol-sensing device comprising a thin-film sensor made of graphene nanosheets (GNs) and bacterial cellulose nanofibers (BCNs). We show that the GN/BCN sensor has a high selectivity to ethanol by distinguishing liquid-phase or vapor-phase ethanol (C2H6O) from water (H2O) intelligently with accurate transformation into electrical signals in devices. The BCN component of the film amplifies the ethanol sensitivity of the film, whereby the GN/BCN sensor has 12400% sensitivity for vapor-phase ethanol compared to the pure GN sensor, which has only 21% sensitivity. Finally, GN/BCN sensors demonstrate fast response/recovery times and a wide range of alcohol detection (10-100%). The superior sensing ability of GN/BCN compared to GNs alone is due to the improved wettability of BCNs and the ionization of liquids. We prove a facile, green, low-cost route for the assembly of ethanol-sensing devices with potential for vast application.

  1. Operating Cooperatively (OC sensor for highly specific recognition of nucleic acids.

    Directory of Open Access Journals (Sweden)

    Evan M Cornett

    Full Text Available Molecular Beacon (MB probes have been extensively used for nucleic acid analysis because of their ability to produce fluorescent signal in solution instantly after hybridization. The indirect binding of MB probe to a target analyte offers several advantages, including: improved genotyping accuracy and the possibility to analyse folded nucleic acids. Here we report on a new design for MB-based sensor, called 'Operating Cooperatively' (OC, which takes advantage of indirect binding of MB probe to a target analyte. The sensor consists of two unmodified DNA strands, which hybridize to a universal MB probe and a nucleic acid analyte to form a fluorescent complex. OC sensors were designed to analyze two human SNPs and E. coli 16S rRNA. High specificity of the approach was demonstrated by the detection of true analyte in over 100 times excess amount of single base substituted analytes. Taking into account the flexibility in the design and the simplicity in optimization, we conclude that OC sensors may become versatile and efficient tools for instant DNA and RNA analysis in homogeneous solution.

  2. The temperature dependence of the chiral condensate in the Schwinger model with Matrix Product States

    International Nuclear Information System (INIS)

    Saito, H; Jansen, K.; Cichy, K.; Frankfurt Univ.; Poznan Univ.

    2014-12-01

    We present our recent results for the tensor network (TN) approach to lattice gauge theories. TN methods provide an efficient approximation for quantum many-body states. We employ TN for one dimensional systems, Matrix Product States, to investigate the 1-flavour Schwinger model. In this study, we compute the chiral condensate at finite temperature. From the continuum extrapolation, we obtain the chiral condensate in the high temperature region consistent with the analytical calculation by Sachs and Wipf.

  3. Calix[4]arenes Containing a Ureido Functionality on the Lower Rim as Highly Efficient Receptors for Anion Recognition.

    Czech Academy of Sciences Publication Activity Database

    Klejch, T.; Slavíček, J.; Hudeček, O.; Eigner, V.; Gutierrez, Natalia Andrea; Cuřínová, Petra; Lhoták, P.

    2016-01-01

    Roč. 40, č. 9 (2016), s. 7935-7942 ISSN 1144-0546 Institutional support: RVO:67985858 Keywords : calix[4]arene * anion recognition * receptors Subject RIV: CC - Organic Chemistry Impact factor: 3.269, year: 2016

  4. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Ebert, D.; Volkov, M.K.

    1981-01-01

    The pion polarizability is calculated in a chiral meson-quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Llanta and Tarrach is given. (orig.)

  5. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ehbert, D.

    1981-01-01

    The pion polarizability is calculated in a chiral meson- quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Llanta and Tarrach is given [ru

  6. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ebert, D.

    1981-01-01

    It is shown that the pion polarizability calculated in a chiral model with quark loops agrees exactly with the analogous quantity found in a chiral meson-baryon model. The results of a paper by Llanta and Tarrach are discussed critically

  7. Massive states in chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

    1995-08-01

    It is shown that the chiral nonanalytic terms generated by {Delta}{sub 33} resonance in the nucleon self-energy is reproduced in chiral perturbation theory by perturbing appropriate local operators contained in the pion-nucleon effective Lagrangian itself. (orig.)

  8. 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

  9. Pentaquarks in chiral color dielectric model

    Indian Academy of Sciences (India)

    Recent experiments indicate that a narrow baryonic state having strangeness +1 and mass of about 1540 MeV may be existing. Such a state was predicted in chiral model by Diakonov et al. In this work I compute the mass and width of this state in chiral color dielectric model. I show that the computed width is about 30 MeV.

  10. Orientation-Dependent Handedness and Chiral Design

    Directory of Open Access Journals (Sweden)

    Efi Efrati

    2014-01-01

    Full Text Available 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 gravity, log gravity, and extremal CFT

    International Nuclear Information System (INIS)

    Maloney, Alexander; Song Wei; Strominger, Andrew

    2010-01-01

    We show that the linearization of all exact solutions of classical chiral gravity around the AdS 3 vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

  12. Chirality in nonlinear optics and optical switching

    NARCIS (Netherlands)

    Meijer, E.W.; Feringa, B.L.

    1993-01-01

    Chirality in molecular opto-electronics is limited sofar to the use of optically active liquid crystals and a number of optical phenomena are related to the helical macroscopic structure obtained by using one enantiomer, only. In this paper, the use of chirality in nonlinear optics and optical

  13. On infinite regular and chiral maps

    OpenAIRE

    Arredondo, John A.; Valdez, Camilo Ramírez y Ferrán

    2015-01-01

    We prove that infinite regular and chiral maps take place on surfaces with at most one end. Moreover, we prove that an infinite regular or chiral map on an orientable surface with genus can only be realized on the Loch Ness monster, that is, the topological surface of infinite genus with one end.

  14. Chiral bosonization on a Riemann surface

    International Nuclear Information System (INIS)

    Eguchi, Tohru; Ooguri, Hirosi

    1987-01-01

    We point out that the basic addition theorem of θ-functions, Fay's identity, implies an equivalence between bosons and chiral fermions on Riemann surfaces with arbitrary genus. We present a rule for a bosonized calculation of correlation functions. We also discuss ghost systems of n and (1-n) tensors and derive formulas for their chiral determinants. (orig.)

  15. Dual chiral density wave in quark matter

    International Nuclear Information System (INIS)

    Tatsumi, Toshitaka

    2002-01-01

    We prove that quark matter is unstable for forming a dual chiral density wave above a critical density, within the Nambu-Jona-Lasinio model. Presence of a dual chiral density wave leads to a uniform ferromagnetism in quark matter. A similarity with the spin density wave theory in electron gas and the pion condensation theory is also pointed out. (author)

  16. 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

  17. Chiralities of spiral waves and their transitions.

    Science.gov (United States)

    Pan, Jun-ting; Cai, Mei-chun; Li, Bing-wei; Zhang, Hong

    2013-06-01

    The chiralities of spiral waves usually refer to their rotation directions (the turning orientations of the spiral temporal movements as time elapses) and their curl directions (the winding orientations of the spiral spatial geometrical structures themselves). Traditionally, they are the same as each other. Namely, they are both clockwise or both counterclockwise. Moreover, the chiralities are determined by the topological charges of spiral waves, and thus they are conserved quantities. After the inwardly propagating spirals were experimentally observed, the relationship between the chiralities and the one between the chiralities and the topological charges are no longer preserved. The chiralities thus become more complex than ever before. As a result, there is now a desire to further study them. In this paper, the chiralities and their transition properties for all kinds of spiral waves are systemically studied in the framework of the complex Ginzburg-Landau equation, and the general relationships both between the chiralities and between the chiralities and the topological charges are obtained. The investigation of some other models, such as the FitzHugh-Nagumo model, the nonuniform Oregonator model, the modified standard model, etc., is also discussed for comparison.

  18. Insights on some chiral smectic phases

    Indian Academy of Sciences (India)

    journal of. August 2003 physics pp. 285–295. Insights on some chiral ... Liquid crystals; smectics; chirality; frustrated phases; twist grain boundary phases. ... molecules are more or less packed in layers and smectic phases can be seen ..... (imaging plate or CCD camera) which was located at about 300 mm from the sample.

  19. Scanning patterns of faces do not explain impaired emotion recognition in Huntington Disease: Evidence for a high level mechanism

    Directory of Open Access Journals (Sweden)

    Marieke evan Asselen

    2012-02-01

    Full Text Available Previous studies in patients with amygdala lesions suggested that deficits in emotion recognition might be mediated by impaired scanning patterns of faces. Here we investigated whether scanning patterns also contribute to the selective impairment in recognition of disgust in Huntington disease (HD. To achieve this goal, we recorded eye movements during a two-alternative forced choice emotion recognition task. HD patients in presymptomatic (n=16 and symptomatic (n=9 disease stages were tested and their performance was compared to a control group (n=22. In our emotion recognition task, participants had to indicate whether a face reflected one of six basic emotions. In addition, and in order to define whether emotion recognition was altered when the participants were forced to look at a specific component of the face, we used a second task where only limited facial information was provided (eyes/mouth in partially masked faces. Behavioural results showed no differences in the ability to recognize emotions between presymptomatic gene carriers and controls. However, an emotion recognition deficit was found for all 6 basic emotion categories in early stage HD. Analysis of eye movement patterns showed that patient and controls used similar scanning strategies. Patterns of deficits were similar regardless of whether parts of the faces were masked or not, thereby confirming that selective attention to particular face parts is not underlying the deficits. These results suggest that the emotion recognition deficits in symptomatic HD patients cannot be explained by impaired scanning patterns of faces. Furthermore, no selective deficit for recognition of disgust was found in presymptomatic HD patients.

  20. Estimating brain age using high-resolution pattern recognition: Younger brains in long-term meditation practitioners.

    Science.gov (United States)

    Luders, Eileen; Cherbuin, Nicolas; Gaser, Christian

    2016-07-01

    Normal aging is known to be accompanied by loss of brain substance. The present study was designed to examine whether the practice of meditation is associated with a reduced brain age. Specific focus was directed at age fifty and beyond, as mid-life is a time when aging processes are known to become more prominent. We applied a recently developed machine learning algorithm trained to identify anatomical correlates of age in the brain translating those into one single score: the BrainAGE index (in years). Using this validated approach based on high-dimensional pattern recognition, we re-analyzed a large sample of 50 long-term meditators and 50 control subjects estimating and comparing their brain ages. We observed that, at age fifty, brains of meditators were estimated to be 7.5years younger than those of controls. In addition, we examined if the brain age estimates change with increasing age. While brain age estimates varied only little in controls, significant changes were detected in meditators: for every additional year over fifty, meditators' brains were estimated to be an additional 1month and 22days younger than their chronological age. Altogether, these findings seem to suggest that meditation is beneficial for brain preservation, effectively protecting against age-related atrophy with a consistently slower rate of brain aging throughout life. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Using of FPGA coprocessor for improving the execution speed of the pattern recognition algorithm for ATLAS - high energy physics experiment

    CERN Document Server

    Hinkelbein, C; Kugel, A; Männer, R; Miiller, M

    2004-01-01

    Pattern recognition algorithms are used in experimental High Energy physics for getting parameters (features) of particles tracks in detectors. It is particularly important to have fast algorithms in trigger system. This paper investigates the suitability of using FPGA coprocessor for speedup of the TRT-LUT algorithm - one of the feature extraction algorithms for second level trigger for ATLAS experiment (CERN). Two realization of the same algorithm have been compared: C++ realization tested on a computer equipped with dual Xeon 2.4 GHz CPU, 64-bit, 66MHz PCI bus, 1024Mb DDR RAM main memories with Red Hat Linux 7.1 and hybrid C++ - VHDL realisation tested on same PC equipped in addition by MPRACE board (FPGA-Coprocessor board based on Xilinx Virtex-II FPGA and made as 64-bit, 66 MHz PCI card developed at the University of Mannheim). Usage of the FPGA coprocessor can give some reasonable speedup in contrast to general purpose processor only for those algorithms (or parts of algorithms), for which there is a po...

  2. Chiral tunneling in a twisted graphene bilayer.

    Science.gov (United States)

    He, Wen-Yu; Chu, Zhao-Dong; He, Lin

    2013-08-09

    The perfect transmission in a graphene monolayer and the perfect reflection in a Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in a twisted graphene bilayer show an adjustable probability of chiral tunneling for normal incidence: they can be changed from perfect tunneling to partial or perfect reflection, or vice versa, by controlling either the height of the barrier or the incident energy. As well as addressing basic physics about how the chiral fermions with different chiralities tunnel through a barrier, our results provide a facile route to tune the electronic properties of the twisted graphene bilayer.

  3. Hadron properties in chiral sigma model

    International Nuclear Information System (INIS)

    Shen Hong

    2005-01-01

    The modification of hadron masses in nuclear medium is studied by using the chiral sigma model, which is extended to generate the omega meson mass by the sigma condensation in the vacuum in the same way as the nucleon mass. The chiral sigma model provides proper equilibrium properties of nuclear matter. It is shown that the effective masses of both nucleons and omega mesons decrease in nuclear medium, while the effective mass of sigma mesons increases oat finite density in the chiral sigma model. The results obtained in the chiral sigma model are compared with those obtained in the Walecka model, which includes sigma and omega mesons in a non-chiral fashion. (author)

  4. Cosmic chirality both true and false.

    Science.gov (United States)

    Barron, Laurence D

    2012-12-01

    The discrete symmetries of parity P, time reversal T, and charge conjugation C may be used to characterize the properties of chiral systems. It is well known that parity violation infiltrates into ordinary matter via an interaction between the nucleons and electrons, mediated by the Z(0) particle, that lifts the degeneracy of the mirror-image enantiomers of a chiral molecule. Being odd under P but even under T, this P-violating interaction exhibits true chirality and so may induce absolute enantioselection under all circumstances. It has been suggested that CP violation may also infiltrate into ordinary matter via a P-odd, T-odd interaction mediated by the (as yet undetected) axion. This CP-violating interaction exhibits false chirality and so may induce absolute enantioselection in processes far from equilibrium. Both true and false cosmic chirality should be considered together as possible sources of homochirality in the molecules of life. Copyright © 2012 Wiley Periodicals, Inc.

  5. Genetically programmed chiral organoborane synthesis

    Science.gov (United States)

    Kan, S. B. Jennifer; Huang, Xiongyi; Gumulya, Yosephine; Chen, Kai; Arnold, Frances H.

    2017-12-01

    Recent advances in enzyme engineering and design have expanded nature’s catalytic repertoire to functions that are new to biology. However, only a subset of these engineered enzymes can function in living systems. Finding enzymatic pathways that form chemical bonds that are not found in biology is particularly difficult in the cellular environment, as this depends on the discovery not only of new enzyme activities, but also of reagents that are both sufficiently reactive for the desired transformation and stable in vivo. Here we report the discovery, evolution and generalization of a fully genetically encoded platform for producing chiral organoboranes in bacteria. Escherichia coli cells harbouring wild-type cytochrome c from Rhodothermus marinus (Rma cyt c) were found to form carbon-boron bonds in the presence of borane-Lewis base complexes, through carbene insertion into boron-hydrogen bonds. Directed evolution of Rma cyt c in the bacterial catalyst provided access to 16 novel chiral organoboranes. The catalyst is suitable for gram-scale biosynthesis, providing up to 15,300 turnovers, a turnover frequency of 6,100 h-1, a 99:1 enantiomeric ratio and 100% chemoselectivity. The enantiopreference of the biocatalyst could also be tuned to provide either enantiomer of the organoborane products. Evolved in the context of whole-cell catalysts, the proteins were more active in the whole-cell system than in purified forms. This study establishes a DNA-encoded and readily engineered bacterial platform for borylation; engineering can be accomplished at a pace that rivals the development of chemical synthetic methods, with the ability to achieve turnovers that are two orders of magnitude (over 400-fold) greater than those of known chiral catalysts for the same class of transformation. This tunable method for manipulating boron in cells could expand the scope of boron chemistry in living systems.

  6. Omega-3 fatty acids revert high-fat diet-induced neuroinflammation but not recognition memory impairment in rats.

    Science.gov (United States)

    de Andrade, Aline Marcelino; Fernandes, Marilda da Cruz; de Fraga, Luciano Stürmer; Porawski, Marilene; Giovenardi, Márcia; Guedes, Renata Padilha

    2017-12-01

    Neuroinflammation is a consequence of overeating and may predispose to the development of cognitive decline and neurological disorders. This study aimed to evaluate the impact of omega-3 supplementation on memory and neuroinflammatory markers in rats fed a high-fat diet. Male Wistar rats were divided into four groups: standard diet (SD); standard diet + omega-3 (SD + O); high fat diet (HFD); and high fat diet + omega-3 (HFD + O). Diet administration was performed for 20 weeks and omega-3 supplementation started at the 16th week. HFD significantly increased body weight, while omega-3 supplementation did not modify the total weight gain. However, animals from the HFD + O group showed a lower level of visceral fat along with an improvement in insulin sensitivity following HFD. Thus, our results demonstrate a beneficial metabolic role of omega-3 following HFD. On the other hand, HFD animals presented an impairment in object recognition memory, which was not recovered by omega-3. In addition, there was an increase in GFAP-positive cells in the cerebral cortex of the HFD group, showing that omega-3 supplementation can be effective to decrease astrogliosis. However, no differences in GFAP number of cells were found in the hippocampus. We also demonstrated a significant increase in gene expression of pro-inflammatory cytokines IL-6 and TNF-α in cerebral cortex of the HFD group, reinforcing the anti-inflammatory role of this family of fatty acids. In summary, omega-3 supplementation was not sufficient to reverse the memory deficit caused by HFD, although it played an important role in reducing the neuroinflammatory profile. Therefore, omega-3 fatty acids may play an important role in the central nervous system, preventing the progression of neuroinflammation in obesity.

  7. Principal chiral model on superspheres

    International Nuclear Information System (INIS)

    Mitev, V.; Schomerus, V.; Quella, T.

    2008-09-01

    We investigate the spectrum of the principal chiral model (PCM) on odd-dimensional superspheres as a function of the curvature radius R. For volume-filling branes on S 3 vertical stroke 2 , we compute the exact boundary spectrum as a function of R. The extension to higher dimensional superspheres is discussed, but not carried out in detail. Our results provide very convincing evidence in favor of the strong-weak coupling duality between supersphere PCMs and OSP(2S+2 vertical stroke 2S) Gross-Neveu models that was recently conjectured by Candu and Saleur. (orig.)

  8. Nuclear forces and chiral theories

    International Nuclear Information System (INIS)

    Friar, J.L.; Washington Univ., Seattle, WA

    1995-01-01

    Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force will also be discussed in this context

  9. Chiral quarks and proton decay

    International Nuclear Information System (INIS)

    Chadha, S.; Daniel, M.; Gounaris, G.J.; Murphy, A.J.

    1984-04-01

    The authors calculate the hadronic matrix elements of baryon decay operators using a chiral effective Lagrangian with quarks, gluons and Goldstone boson fields. The cases where the ΔB=1 operators arise from supersymmetric SU(5) GUT as well as the minimal SU(5) GUT model are studied. In each model the results depend on two parameters. In particular there is a range of values for the two parameters, where the dominant decay modes in the minimal SU(5) GUT are: p→etae + and n→π - e + . (author)

  10. Separation of Alkyne Enantiomers by Chiral Column HPLC Analysis of Their Cobalt-Complexes

    Directory of Open Access Journals (Sweden)

    Qiaoyun Liu

    2017-03-01

    Full Text Available Separation of the enantiomers of new chiral alkynes in strategic syntheses and bioorthogonal studies is always problematic. The chiral column high-performance liquid chromatography (HPLC method in general could not be directly used to resolve such substrates, since the differentiation of the alkyne segment with the other alkane/alkene segment is not significant in the stationary phase, and the alkyne group is not a good UV chromophore. Usually, a pre-column derivatization reaction with a tedious workup procedure is needed. Making use of easily-prepared stable alkyne-cobalt-complexes, we developed a simple and general method by analyzing the in situ generated cobalt-complex of chiral alkynes using chiral column HPLC. This new method is especially suitable for the alkynes without chromophores and other derivable groups.

  11. 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.

  12. Degenerate and chiral states in the extended Heisenberg model on the kagome lattice

    Science.gov (United States)

    Gómez Albarracín, F. A.; Pujol, P.

    2018-03-01

    We present a study of the low-temperature phases of the antiferromagnetic extended classical Heisenberg model on the kagome lattice, up to third-nearest neighbors. First, we focus on the degenerate lines in the boundaries of the well-known staggered chiral phases. These boundaries have either semiextensive or extensive degeneracy, and we discuss the partial selection of states by thermal fluctuations. Then, we study the model under an external magnetic field on these lines and in the staggered chiral phases. We pay particular attention to the highly frustrated point, where the three exchange couplings are equal. We show that this point can be mapped to a model with spin-liquid behavior and nonzero chirality. Finally, we explore the effect of Dzyaloshinskii-Moriya (DM) interactions in two ways: a homogeneous and a staggered DM interaction. In both cases, there is a rich low-temperature phase diagram, with different spontaneously broken symmetries and nontrivial chiral phases.

  13. 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.

  14. Synthesis and characterization of mixed ligand chiral nanoclusters

    KAUST Repository

    Guven, Zekiye P.; Ustbas, Burcin; Harkness, Kellen M.; Coskun, Hikmet; Joshi, Chakra Prasad; Besong, Tabot M.D.; Stellacci, Francesco; Bakr, Osman; Akbulut, Ozge

    2016-01-01

    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.

  15. Chiral symmetry breaking and cooling in lattice QCD

    International Nuclear Information System (INIS)

    Woloshyn, R.M.; Lee, F.X.

    1995-08-01

    Chiral symmetry breaking is calculated as a function of cooling in quenched lattice QCD. A non-zero signal is found for the chiral condensate beyond one hundred cooling steps, suggesting that there is chiral symmetry breaking associated with instantons. Quantitatively, the chiral condensate in cooled gauge field configurations is small compared to the value without cooling. (author) 7 refs., 1 tab., 3 figs

  16. A Review on Chiral Chromatography and its Application to the ...

    African Journals Online (AJOL)

    MoZarD

    amounts of material and is for measuring the relative proportions of ... the stationary phase must themselves be made chiral, giving differing ... electrophoretic medium that change it to chiral mobile phase (Eliel, et ... column containing a chiral stationary phase is also called a chiral ... densitometry, and a TLC method for the.

  17. Quantification of susceptibility change at high-concentrated SPIO-labeled target by characteristic phase gradient recognition.

    Science.gov (United States)

    Zhu, Haitao; Nie, Binbin; Liu, Hua; Guo, Hua; Demachi, Kazuyuki; Sekino, Masaki; Shan, Baoci

    2016-05-01

    Phase map cross-correlation detection and quantification may produce highlighted signal at superparamagnetic iron oxide nanoparticles, and distinguish them from other hypointensities. The method may quantify susceptibility change by performing least squares analysis between a theoretically generated magnetic field template and an experimentally scanned phase image. Because characteristic phase recognition requires the removal of phase wrap and phase background, additional steps of phase unwrapping and filtering may increase the chance of computing error and enlarge the inconsistence among algorithms. To solve problem, phase gradient cross-correlation and quantification method is developed by recognizing characteristic phase gradient pattern instead of phase image because phase gradient operation inherently includes unwrapping and filtering functions. However, few studies have mentioned the detectable limit of currently used phase gradient calculation algorithms. The limit may lead to an underestimation of large magnetic susceptibility change caused by high-concentrated iron accumulation. In this study, mathematical derivation points out the value of maximum detectable phase gradient calculated by differential chain algorithm in both spatial and Fourier domain. To break through the limit, a modified quantification method is proposed by using unwrapped forward differentiation for phase gradient generation. The method enlarges the detectable range of phase gradient measurement and avoids the underestimation of magnetic susceptibility. Simulation and phantom experiments were used to quantitatively compare different methods. In vivo application performs MRI scanning on nude mice implanted by iron-labeled human cancer cells. Results validate the limit of detectable phase gradient and the consequent susceptibility underestimation. Results also demonstrate the advantage of unwrapped forward differentiation compared with differential chain algorithms for susceptibility

  18. Dynamic Covalent Chemistry within Biphenyl Scaffolds: Reversible Covalent Bonding, Control of Selectivity, and Chirality Sensing with a Single System.

    Science.gov (United States)

    Ni, Cailing; Zha, Daijun; Ye, Hebo; Hai, Yu; Zhou, Yuntao; Anslyn, Eric V; You, Lei

    2018-01-26

    Axial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a versatile platform for the binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between an open aldehyde and its cyclic hemiaminal within biphenyl derivatives enabled the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. Selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central-to-axial chirality transfer, the handedness and ee values of chiral monoalcohol and monoamine analytes were reported by circular dichroism. The strategies introduced herein should find application in many contexts, including assembly, sensing, and labeling. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Gamma-radiolysis of chiral molecules: R(+)-limonene, S(-)-limonene and R(-)-a-phellandrene

    International Nuclear Information System (INIS)

    Cataldo, F.

    2004-01-01

    Three isomeric chiral terpenes, R(+)-limonene, S(-)-limonene and R(-)-α-phellandrene were γ-radiolyzed in sealed vials at room temperature with a total radiation dose of 317 kGy. The radiolyzed samples were analyzed by FT-IR, electronic absorption spectroscopy, liquid chromatography using a diode-array detector (HPLC-DAD) and by polarimetry. Despite a relatively high radiation dose used, all the chiral molecules selected have shown a low radioracemization rate. This fact and the role played by the impurities in the selective radio-degradation of one of the two enantiomers has been discussed in the context of the origin of chirality in prebiotic molecules and the chirality enhancement in a prebiotic world. The results were also discussed in the frame of the radiosterilization technique of chiral drugs, perfumes and food components. (author)

  20. Lithium Enolates in the Enantioselective Construction of Tetrasubstituted Carbon Centers with Chiral Lithium Amides as Noncovalent Stereodirecting Auxiliaries.

    Science.gov (United States)

    Yu, Kai; Lu, Ping; Jackson, Jeffrey J; Nguyen, Thuy-Ai D; Alvarado, Joseph; Stivala, Craig E; Ma, Yun; Mack, Kyle A; Hayton, Trevor W; Collum, David B; Zakarian, Armen

    2017-01-11

    Lithium enolates derived from carboxylic acids are ubiquitous intermediates in organic synthesis. Asymmetric transformations with these intermediates, a central goal of organic synthesis, are typically carried out with covalently attached chiral auxiliaries. An alternative approach is to utilize chiral reagents that form discrete, well-defined aggregates with lithium enolates, providing a chiral environment conducive of asymmetric bond formation. These reagents effectively act as noncovalent, or traceless, chiral auxiliaries. Lithium amides are an obvious choice for such reagents as they are known to form mixed aggregates with lithium enolates. We demonstrate here that mixed aggregates can effect highly enantioselective transformations of lithium enolates in several classes of reactions, most notably in transformations forming tetrasubstituted and quaternary carbon centers. Easy recovery of the chiral reagent by aqueous extraction is another practical advantage of this one-step protocol. Crystallographic, spectroscopic, and computational studies of the central reactive aggregate, which provide insight into the origins of selectivity, are also reported.

  1. Engineering of an Extremely Thermostable Alpha/Beta Barrel Scaffold to Serve as a High Affinity Molecular Recognition Element for Use in Sensor Applications

    Science.gov (United States)

    2015-12-23

    Molecular Recognition Element For Use in Sensor Applications Report Title The overall goal of the project was to evolve a highly thermostable enzyme ( alcohol ...SECURITY CLASSIFICATION OF: The overall goal of the project was to evolve a highly thermostable enzyme ( alcohol dehydrogenase D (AdhD) from Pyrococcus...furiosus) to bind an explosive molecule, RDX. The enzyme naturally catalyzes the nicotinamide cofactor-dependent oxidation or reduction of alcohols

  2. Mirror Symmetry Breaking by Chirality Synchronisation in Liquids and Liquid Crystals of Achiral Molecules.

    Science.gov (United States)

    Tschierske, Carsten; Ungar, Goran

    2016-01-04

    Spontaneous mirror symmetry breaking is an efficient way to obtain homogeneously chiral agents, pharmaceutical ingredients and materials. It is also in the focus of the discussion around the emergence of uniform chirality in biological systems. Tremendous progress has been made by symmetry breaking during crystallisation from supercooled melts or supersaturates solutions and by self-assembly on solid surfaces and in other highly ordered structures. However, recent observations of spontaneous mirror symmetry breaking in liquids and liquid crystals indicate that it is not limited to the well-ordered solid state. Herein, progress in the understanding of a new dynamic mode of symmetry breaking, based on chirality synchronisation of transiently chiral molecules in isotropic liquids and in bicontinuous cubic, columnar, smectic and nematic liquid crystalline phases is discussed. This process leads to spontaneous deracemisation in the liquid state under thermodynamic control, giving rise to long-term stable symmetry-broken fluids, even at high temperatures. These fluids form conglomerates that are capable of extraordinary strong chirality amplification, eventually leading to homochirality and providing a new view on the discussion of emergence of uniform chirality in prebiotic systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Broadband and chiral binary dielectric meta-holograms.

    Science.gov (United States)

    Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Kanhaiya, Pritpal; Capasso, Federico

    2016-05-01

    Subwavelength structured surfaces, known as meta-surfaces, hold promise for future compact and optically thin devices with versatile functionalities. By revisiting the concept of detour phase, we demonstrate high-efficiency holograms with broadband and chiral imaging functionalities. In our devices, the apertures of binary holograms are replaced by subwavelength structured microgratings. We achieve broadband operation from the visible to the near infrared and efficiency as high as 75% in the 1.0 to 1.4 μm range by compensating for the inherent dispersion of the detour phase with that of the subwavelength structure. In addition, we demonstrate chiral holograms that project different images depending on the handedness of the reference beam by incorporating a geometric phase. Our devices' compactness, lightness, and ability to produce images even at large angles have significant potential for important emerging applications such as wearable optics.

  4. Nucleic acids, proteins, and chirality

    Science.gov (United States)

    Usher, D. A.; Profy, A. T.; Walstrum, S. A.; Needels, M. C.; Bulack, S. C.; Lo, K. M.

    1984-01-01

    The present investigation is concerned with experimental results related, in one case, to the chirality of nucleotides, and, in another case, to the possibility of a link between the chirality of nucleic acids, and that of peptides. It has been found that aminoacylation of the 'internal' hydroxyl group of a dinucleoside monophosphate can occur stereoselectively. However, this reaction has not yet been made a part of a working peptide synthesis scheme. The formation and cleavage of oligonucleotides is considered. In the event of the formation of a helical complex between the oligonucleotide and the polymer, 1-prime,5-prime-bonds in the oligomer are found to become more resistant towards cleavage. The conditions required for peptide bond formation are examined, taking into account the known structures of RNA and possible mechanisms for prebiotic peptide bond formation. The possibility is considered that the 2-prime,5-prime-internucleotide linkage could have played an important part in the early days of biological peptide synthesis.

  5. Hierarchical chirality transfer in the growth of Towel Gourd tendrils

    Science.gov (United States)

    Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

    2013-01-01

    Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties. PMID:24173107

  6. Chiral lewis Acid catalysis in nitrile oxide cycloadditions.

    Science.gov (United States)

    Sibi, Mukund P; Itoh, Kennosuke; Jasperse, Craig P

    2004-05-05

    We describe examples of highly regio- and enantioselective nitrile oxide cycloadditions to unsaturated alkenes using substoichiometric amounts of a chiral Lewis acid. Pyrazolidinones proved to be effective achiral templates in the cycloadditions providing C-adducts typically in >30:1 selectivity and 80-99% ee. To avoid potential problems involving coordination of the Lewis acid by amine bases, we have devised a novel method for the generation of unstable nitrile oxides from hydroximinoyl chlorides using Amberlyst 21 as the base.

  7. Chirality sensing with stereodynamic copper(I) complexes.

    Science.gov (United States)

    De Los Santos, Zeus A; Legaux, Nicholas M; Wolf, Christian

    2017-11-01

    Three Cu(I) complexes derived from stereodynamic diphosphine ligands were synthesized and used for chirality sensing. The coordination of diamines and amino acids to these complexes generates distinct circular dichroism signals. The chiroptical sensor response allows determination of the absolute configuration and the enantiomeric excess of the analyte at low concentrations. This method is operationally simple, fast, and attractive for high-throughput sensing applications. © 2017 Wiley Periodicals, Inc.

  8. Chiral symmetry breaking in gauge theories from Reggeon diagram analysis

    International Nuclear Information System (INIS)

    White, A.R.

    1991-01-01

    It is argued that reggeon diagrams can be used to study dynamical properties of gauge theories containing a large number of massless fermions. SU(2) gauge theory is studied in detail and it is argued that there is a high energy solution which is analogous to the solution of the massless Schwinger model. A generalized winding-number condensate produces the massless pseudoscalar spectrum associated with chiral symmetry breaking and a ''trivial'' S-Matrix

  9. Supersymmetric chiral electrodynamics as a renormalized theory

    International Nuclear Information System (INIS)

    Ansel'm, A.A.; Iogansen, A.A.

    1991-01-01

    It is well know that the QED of chiral fermions is a nonrenormalizable theory, inasmuch as the gauge current in it is not conserved because of the presence of an anomaly. It is evident that in this theory unitarity is also violated. The principal object of investigation in the present paper is supersymmetric chiral QED, supersymmetric QED is a renormalizable theory. This happens because the radiative corrections generate here a charged current of a chiral fermion that appears in the chiral (i.e., longitudinal) part of the vector supermultiplet. At first sight, the chiral part of the vector multiplet is unphysical and contains only supergauge degrees of freedom. However, this is valid only at the classical level, whereas, because of the anomaly, the radiative corrections lead to nonconservation of the gauge current, as a result of which the degrees of freedom associated with the chiral part of the vector multiplet become physical. On the other hand, owing to the nonconservation of the gauge charge, the apparently neutral fermion appearing int he chiral (longitudinal) part of the vector superfield becomes charged

  10. Quantitative and pattern recognition analysis of five marker compounds in Raphani semen using high-performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yeon Woo; Lee, Joo Sang; Zhao, Bing Tian; Woo, Mi Hee; Min, Byung Sun [College of Pharmacy, Drug Research and Development Center, Catholic University of Daegu, Gyeongsan (Korea, Republic of); Kim, Jeong Ah [College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu (Korea, Republic of); Eun, Rhan Woo [College of Pharmacy, Chosun University, Gwangju (Korea, Republic of)

    2015-09-15

    A rapid and simple high-performance liquid chromatography (HPLC)-photodiode array (PDA) analytical method was developed for the quantitative analysis of Raphani Semen (RS). This method was successfully used to determine the five main phenolic compounds found in RS specimens from different production regions. The compounds included sinapine thiocyanate (1), β-d-fructofuranosyl-α-d-(6-O-sinapoyl)-glucopyranoside (2), isorhamnetin 3,4′-di-O-β-d-glucoside (3), β-d-(3-O-sinapoyl)-fructofuranosyl-α-d-(6-O-sinapoyl)-glucopyranoside (4), and β-d-(3,4-O-disinapoyl)-fructofuranosyl-α-d-(6-O-sinapoyl)-glucopyranoside (5). The marker compounds were separated using an Agilent Eclipse XDB-C18 column (5.0 µm, 150 × 4.6 mm i.d.) by gradient elution with acetonitrile/water/0.1% trifluoroacetic acid (TFA) as the mobile phase (flow rate, 1.0 mL/min). This method was fully validated with respect to linearity, precision, accuracy, stability, and robustness. The HPLC analytical method was validated to conduct a pattern recognition analysis by repeatedly analyzing 56 seed samples including 55 RS (C01–C49 and K50–K55) and 1 Brassicae Semen samples. In addition, a content standard for RS was proposed. Compounds 1 and 4 were revealed as major components in the HPLC chromatogram, and their contents ranged from 0.06 to 0.20 and 0.02 to 0.35 mg/g, respectively. These results demonstrate the successful development of an analytical method suitable for evaluating the quality and distinguishing the origin of RS. In addition, we briefly describe the crucial liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical conditions for the precise simultaneous quantification of the marker compounds.

  11. Quantitative and pattern recognition analysis of five marker compounds in Raphani semen using high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Jung, Yeon Woo; Lee, Joo Sang; Zhao, Bing Tian; Woo, Mi Hee; Min, Byung Sun; Kim, Jeong Ah; Eun, Rhan Woo

    2015-01-01

    A rapid and simple high-performance liquid chromatography (HPLC)-photodiode array (PDA) analytical method was developed for the quantitative analysis of Raphani Semen (RS). This method was successfully used to determine the five main phenolic compounds found in RS specimens from different production regions. The compounds included sinapine thiocyanate (1), β-d-fructofuranosyl-α-d-(6-O-sinapoyl)-glucopyranoside (2), isorhamnetin 3,4′-di-O-β-d-glucoside (3), β-d-(3-O-sinapoyl)-fructofuranosyl-α-d-(6-O-sinapoyl)-glucopyranoside (4), and β-d-(3,4-O-disinapoyl)-fructofuranosyl-α-d-(6-O-sinapoyl)-glucopyranoside (5). The marker compounds were separated using an Agilent Eclipse XDB-C18 column (5.0 µm, 150 × 4.6 mm i.d.) by gradient elution with acetonitrile/water/0.1% trifluoroacetic acid (TFA) as the mobile phase (flow rate, 1.0 mL/min). This method was fully validated with respect to linearity, precision, accuracy, stability, and robustness. The HPLC analytical method was validated to conduct a pattern recognition analysis by repeatedly analyzing 56 seed samples including 55 RS (C01–C49 and K50–K55) and 1 Brassicae Semen samples. In addition, a content standard for RS was proposed. Compounds 1 and 4 were revealed as major components in the HPLC chromatogram, and their contents ranged from 0.06 to 0.20 and 0.02 to 0.35 mg/g, respectively. These results demonstrate the successful development of an analytical method suitable for evaluating the quality and distinguishing the origin of RS. In addition, we briefly describe the crucial liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical conditions for the precise simultaneous quantification of the marker compounds

  12. Chiral polarization scale of QCD vacuum and spontaneous chiral symmetry breaking

    International Nuclear Information System (INIS)

    Alexandru, Andrei; Horv, Ivan

    2013-01-01

    It has recently been found that dynamics of pure glue QCD supports the low energy band of Dirac modes with local chiral properties qualitatively different from that of a bulk: while bulk modes suppress chirality relative to statistical independence between left and right, the band modes enhance it. The width of such chirally polarized zone – chiral polarization scale bigwedge ch – has been shown to be finite in the continuum limit at fixed physical volume. Here we present evidence that bigwedge ch remains non-zero also in the infinite volume, and is therefore a dynamical scale in the theory. Our experiments in N f = 2+1 QCD support the proposition that the same holds in the massless limit, connecting bigwedge ch to spontaneous chiral symmetry breaking. In addition, our results suggest that thermal agitation in quenched QCD destroys both chiral polarization and condensation of Dirac modes at the same temperature T ch > T c .

  13. The paradigm of Pseudodual Chiral Models

    International Nuclear Information System (INIS)

    Zachos, C.K.; Curtright, T.L.

    1994-01-01

    This is a synopsis and extension of Phys. Rev. D49 5408 (1994). The Pseudodual Chiral Model illustrates 2-dimensional field theories which possess an infinite number of conservation laws but also allow particle production, at variance with naive expectations-a folk theorem of integrable models. We monitor the symmetries of the pseudodual model, both local and nonlocal, as transmutations of the symmetries of the (very different) usual Chiral Model. We refine the conventional algorithm to more efficiently produce the nonlocal symmetries of the model. We further find the canonical transformation which connects the usual chiral model to its fully equivalent dual model, thus contradistinguishing the pseudodual theory

  14. Recent status of the chiral bag model

    International Nuclear Information System (INIS)

    Hosaka, Atsushi; Toki, Hiroshi.

    1995-01-01

    In this note, recent status of the chiral bag model is presented. As it combines the MIT quark bag model and the Skyrme model, the chiral bag model interpolates the two models smoothly as a function of the chiral bag radius R. The correct limit of R → ∞ is reproduced by including the higher order terms in the Ω expansion of the cranking method. It resolves the so-called small g A problem in a class of models where the semiclassical method is used. (author)

  15. A nonlocal model of chiral dynamics

    International Nuclear Information System (INIS)

    Holdom, B.; Terning, J.; Verbeek, K.

    1989-01-01

    We consider a nonlocal generalization of the nonlinear σ model. Our chirally symmetric model couples quarks with self-energy Σ(p) to Goldstone bosons (GBs). By integrating out the quarks we obtain a chiral lagrangian, the parameters of which are finite integrals of Σ(p). We find that chiral symmetry is not sufficient to derive the well-known Pagels-Stokar formula for the GB decay constant. We reproduce the Wess-Zumino term and we illustrate the dependence of other four derivative coefficients on Σ(p). (orig.)

  16. Circularly Polarized Light with Sense and Wavelengths To Regulate Azobenzene Supramolecular Chirality in Optofluidic Medium.

    Science.gov (United States)

    Wang, Laibing; Yin, Lu; Zhang, Wei; Zhu, Xiulin; Fujiki, Michiya

    2017-09-20

    Circularly polarized light (CPL) as a massless physical force causes absolute asymmetric photosynthesis, photodestruction, and photoresolution. CPL handedness has long been believed to be the determining factor in the resulting product's chirality. However, product chirality as a function of the CPL handedness, irradiation wavelength, and irradiation time has not yet been studied systematically. Herein, we investigate this topic using achiral polymethacrylate carrying achiral azobenzene as micrometer-size aggregates in an optofluidic medium with a tuned refractive index. Azobenzene chirality with a high degree of dissymmetry ratio (±1.3 × 10 -2 at 313 nm) was generated, inverted, and switched in multiple cycles by irradiation with monochromatic incoherent CPL (313, 365, 405, and 436 nm) for 20 s using a weak incoherent light source (≈ 30 μW·cm -2 ). Moreover, the optical activity was retained for over 1 week in the dark. Photoinduced chirality was swapped by the irradiating wavelength, regardless of whether the CPL sense was the same. This scenario is similar to the so-called Cotton effect, which was first described in 1895. The tandem choice of both CPL sense and its wavelength was crucial for azobenzene chirality. Our experimental proof and theoretical simulation should provide new insight into the chirality of CPL-controlled molecules, supramolecules, and polymers.

  17. Fluxionally chiral DMAP catalysts: kinetic resolution of axially chiral biaryl compounds.

    Science.gov (United States)

    Ma, Gaoyuan; Deng, Jun; Sibi, Mukund P

    2014-10-27

    Can organocatalysts that incorporate fluxional groups provide enhanced selectivity in asymmetric transformations? To address this issue, we have designed chiral 4-dimethylaminopyridine (DMAP) catalysts with fluxional chirality. These catalysts were found to be efficient in promoting the acylative kinetic resolution of secondary alcohols and axially chiral biaryl compounds with selectivity factors of up to 37 and 51, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Speaker Recognition

    DEFF Research Database (Denmark)

    Mølgaard, Lasse Lohilahti; Jørgensen, Kasper Winther

    2005-01-01

    Speaker recognition is basically divided into speaker identification and speaker verification. Verification is the task of automatically determining if a person really is the person he or she claims to be. This technology can be used as a biometric feature for verifying the identity of a person...

  19. Threshold models of recognition and the recognition heuristic

    Directory of Open Access Journals (Sweden)

    Edgar Erdfelder

    2011-02-01

    Full Text Available According to the recognition heuristic (RH theory, decisions follow the recognition principle: Given a high validity of the recognition cue, people should prefer recognized choice options compared to unrecognized ones. Assuming that the memory strength of choice options is strongly correlated with both the choice criterion and recognition judgments, the RH is a reasonable strategy that approximates optimal decisions with a minimum of cognitive effort (Davis-Stober, Dana, and Budescu, 2010. However, theories of recognition memory are not generally compatible with this assumption. For example, some threshold models of recognition presume that recognition judgments can arise from two types of cognitive states: (1 certainty states in which judgments are almost perfectly correlated with memory strength and (2 uncertainty states in which recognition judgments reflect guessing rather than differences in memory strength. We report an experiment designed to test the prediction that the RH applies to certainty states only. Our results show that memory states rather than recognition judgments affect use of recognition information in binary decisions.

  20. Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

    Energy Technology Data Exchange (ETDEWEB)

    Kalaydzhyan, Tigran, E-mail: tigran@caltech.edu [Department of Physics, University of Illinois, 845 W Taylor Street, Chicago, IL 60607 (United States); Jet Propulsion Laboratory, 4800 Oak Grove Dr, M/S 298, Pasadena, CA 91109 (United States); Murchikova, Elena [TAPIR, California Institute of Technology, MC 350-17, Pasadena, CA 91125 (United States)

    2017-06-15

    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 {sup 3}He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in an 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 (chiral vortical and chiral magnetic waves) and transverse velocity (chiral Alfvén wave). We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.