WorldWideScience

Sample records for chiral separations based

  1. [Separation of enantiomers by supercritical fluid chromatography on polysaccharide derivative-based chiral stationary phases].

    Science.gov (United States)

    Li, Dongyan; Wu, Xi; Hao, Fangli; Yang, Yang; Chen, Xiaoming

    2016-01-01

    Eleven kinds of chiral compounds have been well separated within 10 min on polysaccharide derivative-based chiral stationary phases named Chiralpak IA, IB, IC, ID, IE and IF by supercritical fluid chromatography (SFC). The chiral recognition of these chiral compounds has demonstrated good complementary enantioselectivities of the six chiral columns, which were proved to be useful for chiral SFC. Both the elution time and enantioselectivies could be significantly affected by the modifier types and their concentrations, such as methanol, ethanol and isopropanol, which should be optimized during the experiments. In addition, the solvent versatility of the immobilized chiral stationary phase on the optimization of the chiral separation was helpful. PMID:27319169

  2. Chiral separation in microflows

    OpenAIRE

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

    2005-01-01

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

  3. Enantiomeric Separation of 1-(Benzofuran-2-yl)alkylamines on Chiral Stationary Phases Based on Chiral Crown Ethers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soohyun; Kim, Sang Jun; Hyun, Myung Ho [Pusan National Univ., Busan (Korea, Republic of)

    2012-10-15

    Optically active chiral amines are important as building blocks for pharmaceuticals and as scaffolds for chiral ligands and, consequently, many efforts have been devoted to the development of efficient methods for their preparation. For example, reduction of amine precursors with chiral catalysts, enzymatic kinetic resolution or dynamic kinetic resolution of racemic amines and the direct amination of ketones with transaminases have been developed as the efficient methods for the preparation of optically active chiral amines. During the process of developing or utilizing optically active chiral amines, the methods for the determination of their enantiomeric composition are essential. Among various methods, liquid chromatographic resolution of enantiomers on chiral stationary phases (CSPs) have been known to be one of the most accurate and economic means for the determination of the enantiomeric composition of optically active chiral compounds. Especially, CSPs based on chiral crown ethers have been successfully used for the resolution of racemic primary amines. For example, CSPs based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (CSP 1, Figure 1) or (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 (CSP 2 and CSP 3, Figure 1) have been known to be quite effective for the resolution of cyclic and non-cyclic amines, various fluoroquinolone antibacterials containing a primary amino group, tocainide (antiarrhythmic agent) and its analogues, aryl-a-amino ketones and 3-amino-1,4-benzodiazepin-2-ones.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wenwan Zhong

    2003-08-05

    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.

  5. Mechanical separation of chiral dipoles by chiral light

    CERN Document Server

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

    2013-01-01

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

  6. Silica-based polypeptide-monolithic stationary phase for hydrophilic chromatography and chiral separation.

    Science.gov (United States)

    Zhao, Licong; Yang, Limin; Wang, Qiuquan

    2016-05-13

    Glutathione (GSH)-, somatostatin acetate (ST)- and ovomucoid (OV)-functionalized silica-monolithic stationary phases were designed and synthesized for HILIC and chiral separation using capillary electrochromatography (CEC). GSH, ST and OV were covalently incorporated into the silica skeleton via the epoxy ring-opening reaction between their amino groups and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS) together with polycondensation and copolymerization of tetramethyloxysilane and GPTMS. Not only could the direction and electroosmotic flow magnitude on the prepared GSH-, ST- and OV-silica hybrid monolithic stationary phases be controlled by the pH of the mobile phase, but also a typical HILIC behavior was observed so that the nucleotides and HPLC peptide standard mixture could be baseline separated using an aqueous mobile phase without any acetonitrile during CEC. Moreover, the prepared monolithic columns had a chiral separation ability to separate dl-amino acids. The OV-silica hybrid monolithic column was most effective in chiral separation and could separate dl-glutamic acid (Glu) (the resolution R=1.07), dl-tyrosine (Tyr) (1.57) and dl-histidine (His) (1.06). Importantly, the chiral separation ability of the GSH-silica hybrid monolithic column could be remarkably enhanced when using gold nanoparticles (AuNPs) to fabricate an AuNP-mediated GSH-AuNP-GSH-silica hybrid monolithic column. The R of dl-Glu, dl-Tyr and dl-His reached 1.19, 1.60 and 2.03. This monolithic column was thus applied to separate drug enantiomers, and quantitative separation of all four R/S drug enantiomers were achieved with R ranging from 4.36 to 5.64. These peptide- and protein-silica monolithic stationary phases with typical HILIC separation behavior and chiral separation ability implied their promise for the analysis of not only the future metabolic studies, but also drug enantiomers recognition.

  7. Silica-based polypeptide-monolithic stationary phase for hydrophilic chromatography and chiral separation.

    Science.gov (United States)

    Zhao, Licong; Yang, Limin; Wang, Qiuquan

    2016-05-13

    Glutathione (GSH)-, somatostatin acetate (ST)- and ovomucoid (OV)-functionalized silica-monolithic stationary phases were designed and synthesized for HILIC and chiral separation using capillary electrochromatography (CEC). GSH, ST and OV were covalently incorporated into the silica skeleton via the epoxy ring-opening reaction between their amino groups and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS) together with polycondensation and copolymerization of tetramethyloxysilane and GPTMS. Not only could the direction and electroosmotic flow magnitude on the prepared GSH-, ST- and OV-silica hybrid monolithic stationary phases be controlled by the pH of the mobile phase, but also a typical HILIC behavior was observed so that the nucleotides and HPLC peptide standard mixture could be baseline separated using an aqueous mobile phase without any acetonitrile during CEC. Moreover, the prepared monolithic columns had a chiral separation ability to separate dl-amino acids. The OV-silica hybrid monolithic column was most effective in chiral separation and could separate dl-glutamic acid (Glu) (the resolution R=1.07), dl-tyrosine (Tyr) (1.57) and dl-histidine (His) (1.06). Importantly, the chiral separation ability of the GSH-silica hybrid monolithic column could be remarkably enhanced when using gold nanoparticles (AuNPs) to fabricate an AuNP-mediated GSH-AuNP-GSH-silica hybrid monolithic column. The R of dl-Glu, dl-Tyr and dl-His reached 1.19, 1.60 and 2.03. This monolithic column was thus applied to separate drug enantiomers, and quantitative separation of all four R/S drug enantiomers were achieved with R ranging from 4.36 to 5.64. These peptide- and protein-silica monolithic stationary phases with typical HILIC separation behavior and chiral separation ability implied their promise for the analysis of not only the future metabolic studies, but also drug enantiomers recognition. PMID:27083263

  8. [Separation mechanism of chiral stationary phase based on quinine and crown ether for the direct stereoselective separation of amino acids].

    Science.gov (United States)

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

    2016-01-01

    A novel chiral stationary phase combining quinine and crown ether (QN-CR CSP) was developed to separate amino acid enantiomers. This CSP showed good enantioselectivity for some amino acids. Since the synergistic effect of ion exchange and complexation in chiral recognition of amino acids, a new adsorption isotherm was built. Using the method of frontal analysis by characteristic point (FACP), the adsorption isotherms of tryptophan (Trp) under different mobile phase conditions were determined and fitted the proposed adsorption isotherm model well. With the increase of the competition between metal cationic and amino to crown ether, the equilibrium constant of complexing adsorption was found increased. The chiral separation ability was decreased. The adsorption isotherm improved the understanding of the retention behavior of amino acids on QN-CR CSP, which was also benefit to optimize the structure of the stationary phase.

  9. Screening Approach for Chiral Separation of β-Aminoketones by HPLC on Various Polysaccharide-Based Chiral Stationary Phases.

    Science.gov (United States)

    Addadi, Khadidja; Sekkoum, Khaled; Belboukhari, Nasser; Cheriti, Abdelkrim; Aboul-Enein, Hassan Y

    2015-05-01

    Nine β-aminoketones were synthesized via Mannich reaction when benzaldehyde was condensed with some primary amines and acetophenone. The purified compounds were identified by using spectroscopic methods. The enantiomeric separation of these derivatives was carried out by high-performance liquid chromatography (HPLC) using several coated and immobilized polysaccharide stationary phases, namely, Chiralcel(®) OD-H, Chiralcel(®) OD, Chiralcel(®) OJ, Chiralpak(®) AD, Chiralpak(®) IA, and Chiralpak(®) IB using different mobile phases composed of n-hexane and alcohol mixed in various ratios or pure ethanol or isopropanol. The retention behavior and selectivity of these chiral stationary phases were examined in isocratic normal phase mode. The results indicate that cellulose derivatives have higher enantioselectivity than amylose derivatives for the separation of racemic β-amino ketones. PMID:25752940

  10. Chiral Particle Separation by a Nonchiral Microlattice

    Science.gov (United States)

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

    2012-09-01

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

  11. Separation of Chiral Active Pharmaceutical Ingredients

    DEFF Research Database (Denmark)

    Chaaban, Joussef Hussein

    is regarded as a first step towards a fully continuous PC process. The current knowledge of the importance of crystallization processes in the pharmaceutical industry and the complex thermodynamic and kinetic phenomena accompanied with the separation of chiral compounds are addressed. The experimental work...... public demand, and fierce competition have forced the pharmaceutical industry to redevelop existing methods or develop completely new methods to produce pharmaceuticals consisting of APIs of the desired enantiomer. PC is one of several methods used industrially to obtain pure enantiomers by separation...... covers laboratory studies and the theoretical work is based on the experimental data and observations. A large fraction of active pharmaceutical ingredients (APIs) are enantiomers and the desired biological activity is provided only by one of the enantiomers. Strict regulatory requirements, increasing...

  12. Enantiomeric separation of amlodipine and its two chiral impurities by nano-liquid chromatography and capillary electrochromatography using a chiral stationary phase based on cellulose tris(4-chloro-3-methylphenylcarbamate).

    Science.gov (United States)

    Auditore, Roberta; Santagati, Natale A; Aturki, Zeineb; Fanali, Salvatore

    2013-09-01

    In this work, a novel polysaccharide-based chiral stationary phase, cellulose tris(4-chloro-3-methylphenylcarbamate), also called Sepapak 4 has been evaluated for the chiral separation of amlodipine (AML) and its two impurities. AML is a powerful vasodilatator drug used for the treatment of hypertension. Capillary columns of 100 μm id packed with the chiral stationary phase were used for both nano-LC and CEC experiments. The optimization of the mobile phase composed of ACN/water, (90:10, v/v) containing 15 mM ammonium borate pH 10.0 in nano-LC allowed the chiral separation of AML and the two impurities, but not in a single run. With the purpose to obtain the separation of the three pairs of enantiomers simultaneously, CEC analyses were performed in the same conditions achieving better enantioresolution and higher separation efficiencies for each compound. To fully resolve the mixture of six enantiomers, parameters such as buffer pH and concentration sample injection have been then investigated. A mixture of ACN/water (90:10, v/v) containing 5 mM ammonium borate buffer pH 9.0 enabled the complete separation of the three couples of enantiomers in less than 30 min. The optimized CEC method was therefore validated and applied to the analysis of pharmaceutical formulation declared to contain only AML racemate. PMID:23775281

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

    Science.gov (United States)

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

    2016-07-12

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

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

    Science.gov (United States)

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

    2016-07-01

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

  15. Chiral separation and twin-beam photonics

    Science.gov (United States)

    Bradshaw, David S.; Andrews, David L.

    2016-03-01

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

  16. Mechanistic considerations of enantiorecognition on novel Cinchona alkaloid-based zwitterionic chiral stationary phases from the aspect of the separation of trans-paroxetine enantiomers as model compounds.

    Science.gov (United States)

    Grecsó, Nóra; Kohout, Michal; Carotti, Andrea; Sardella, Roccaldo; Natalini, Benedetto; Fülöp, Ferenc; Lindner, Wolfgang; Péter, Antal; Ilisz, István

    2016-05-30

    The enantiomers of trans-paroxetine were separated on four chiral stationary phases (CSPs) based on chiral zwitterionic Cinchona alkaloids fused with (R,R)- or (S,S)-trans-2-aminocyclohexanesulfonic acid. The enantioseparations were carried out in polar-ionic or in hydro-organic mobile phases with MeOH/THF, MeCN/THF, MeCN/THF/H2O and MeOH/MeCN/THF containing organic acid and base additives, in the temperature range 0-50°C. The effects of the mobile phase composition, the natures and concentrations of the additives and temperature on the separations were investigated. Thermodynamic parameters were calculated from plots of ln α vs 1/T. Δ(ΔH°) ranged between -3.0 and +1.5 kJ mol(-1), and Δ(ΔS°) between -8.8 and +5.9 J mol(-1)K(-1). The enantioseparation was generally enthalpically controlled, the retention factor and separation factor decreasing with increasing temperature, but entropically controlled separation was also observed. The elution sequences of the paroxetine enantiomers on the two pairs of pseudo-enantiomeric CSPs were investigated, and an attempt was made to explain the observed anomalies in silico in order to gain an insight into the underlying molecular recognition events between the four chiral selectors and the analyte enantiomers. PMID:26955754

  17. Enantiomeric separation and simulation studies of pheniramine, oxybutynin, cetirizine, and brinzolamide chiral drugs on amylose-based columns.

    Science.gov (United States)

    Ali, Imran; Al-Othman, Zeid A; Al-Warthan, Abdulrahman; Alam, Syed Dilshad; Farooqi, Javed A

    2014-03-01

    Solid phase extraction (SPE)-chiral separation of the important drugs pheniramine, oxybutynin, cetirizine, and brinzolamide was achieved on the C18 cartridge and AmyCoat (150 x 46 mm) and Chiralpak AD (25 cm x 0.46 cm id) chiral columns in human plasma. Pheniramine, oxybutynin, cetirizine, and brinzolamide were resolved using n-hexane-2-PrOH-DEA (85:15:0.1, v/v), n-hexane-2-PrOH-DEA (80:20:0.1, v/v), n-hexane-2-PrOH-DEA (70:30:0.2, v/v), and n-hexane-2-propanol (90:10, v/v) as mobile phases. The separation was carried out at 25 ± 1 ºC temperature with detection at 225 nm for cetirizine and oxybutynin and 220 nm for pheniramine and brinzolamide. The flow rates of the mobile phases were 0.5 mL min(-1). The retention factors of pheniramine, oxybutynin, cetirizine and brinzolamide were 3.25 and 4.34, 4.76 and 5.64, 6.10 and 6.60, and 1.64 and 2.01, respectively. The separation factors of these drugs were 1.33, 1.18, 1.09 and 1.20 while their resolutions factors were 1.09, 1.45, 1.63 and 1.25, and 1.15, respectively. The absolute configurations of the eluted enantiomers of the reported drugs were determined by simulation studies. It was observed that the order of enantiomers elution of the reported drugs was S-pheniramine > R-pheniramine; R-oxybutynin > S-oxybutynin; S-cetirizine > R-cetirizine; and S-brinzolamide > R-brinzolamide. The mechanism of separation was also determined at the supramolecular level by considering interactions and modeling results. The reported SPE-chiral high-performance liquid chromatography (HPLC) methods are suitable for the enantiomeric analyses of these drugs in any biological sample. In addition, simulation studies may be used to determine the absolute configuration of the first and second eluted enantiomers. PMID:24464520

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

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

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

  19. Chiral separation of pharmaceutical compounds using electrochemically modulated liquid chromatography (EMLC)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.

    1999-02-12

    This research explores the application of a new technique, termed electrochemically modulated liquid chromatography (EMLC), to the chiral separations of pharmaceutical compounds. The introduction section provides a literature review of the technique and its applications, as well as brief overview of the research described in each of the next two chapters. Chapter 2 investigates the EMLC-based enantiomeric separation of a group of chiral benzodiazepines with {beta}-cyclodextrin as a chiral mobile phase additive. Chapter 3 demonstrates the effects of several experimental parameters on the separation efficiency of drug enantiomers. The author concludes with a general summary and possible directions for future studies. Chapters 2 and 3 are processed separately.

  20. A molecular propeller effect for chiral separation and analysis

    OpenAIRE

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

    2015-01-01

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

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

    OpenAIRE

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

    2012-01-01

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

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

    Science.gov (United States)

    Berthod, Alain

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

  3. Chiral magnetic microspheres purified by centrifugal field flow fractionation and microspheres magnetic chiral chromatography for benzoin racemate separation

    OpenAIRE

    Tian, Ailin; Qi, Jing; Liu, Yating; Wang, Fengkang; Ito, Yoichiro; Wei, Yun

    2013-01-01

    Separation of enantiomers still remains a challenge due to their identical physical and chemical properties in a chiral environment, and the research on specific chiral selector along with separation techniques continues to be conducted to resolve individual enantiomers. In our laboratory the promising magnetic chiral microspheres Fe3O4@SiO2@cellulose-2, 3-bis (3, 5-dimethylphenylcarbamate) have been developed to facilitate the resolution using both its magnetic property and chiral recognitio...

  4. Enantiomeric separations of chiral pharmaceuticals using chirally modified tetrahexahedral Au nanoparticles

    Science.gov (United States)

    Shukla, N.; Yang, D.; Gellman, A. J.

    2016-06-01

    Tetrahexahedral (THH, 24-sided) Au nanoparticles modified with D- or L-cysteine (Cys) have been used as enantioselective separators of the chiral pharmaceutical propranolol (PLL) in solution phase. Polarimetry has been used to measure the rotation of linearly polarized light by solutions containing mixtures of PLL and Cys/THH-Au NPs with varying enantiomeric excesses of each. Polarimetry yields clear evidence of enantiospecific adsorption of PLL onto the Cys/THH-Au NPs. This extends prior work using propylene oxide as a test chiral probe, by using the crystalline THH Au NPs with well-defined facets to separate a real pharmaceutical. This work suggests that chiral nanoparticles, coupled with a density separation method such as centrifugation, could be used for enantiomeric purification of real pharmaceuticals. A simple robust model developed earlier has also been used to extract the enantiospecific equilibrium constants for R- and S-PLL adsorption onto the D- and L-Cys/THH-Au NPs.

  5. Enantiomer Separation of α-Dimethyl Dicarboxylate Biphenyl and Related Biphenyl Compounds by Normal Phase HPLC on Polysaccharide Based Chiral Stationary Phases

    Institute of Scientific and Technical Information of China (English)

    LIU,Yue-Qi(刘月启); HAN,Xiao-Qian(韩小茜); Qi,Bang-Feng(齐邦峰); LIU,Chun-Hui(柳春辉); LI,Yong-Min(李永民); CHEN,Li-Ren(陈立仁)

    2002-01-01

    Cellulose tris(4-methylphenylcarbamate), amylose tris(3,5-dimethylpphenylcarbamate) and amylose tris (phenylcarbamate)were prepared by the method reported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel. These final products were used as chiral stationary phases of high performance liquid chromatography for the eighteen structurally related biphenyl conmpounds. The resolution was made using normal-phase methodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, 2-propanol or 1-butanol). The effects of various aliphatic alcohols in the mobile phase were studied. The structural features of the solutes that influence their k'were discussed. A dominant effect of trifluoroaetic acid on chiral separation of aacidicdic solutes was noted.

  6. Recent Advances in Protein Extraction and Chiral Separation of Biomolecules

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Reverse micelles create unique environment in organic media. They are capable of solubilizing hydrophilic biomolecules (e.g., proteins, peptides, amino acids, and DNAs) in their aqueous interior. This feature brings about the practical use of biomaterials in organic media because reverse micelles solubilize them with the intrinsic activity. In this paper, we focus on recent two topics concerning protein extraction and chiral separation of biomolecules using liquid membranes. In the first topic, we present recent attempts to extract proteins from an aqueous solution into isooctane using reverse micelles, and some important operational parameters to achieve an efficient protein transfer are discussed. Furthermore, novel function of reverse micelles as a protein activation medium is introduced. In the reverse micellar phase, denatured proreins were completely reactivated in the reverse micellar solution. The reverse micellar technique is found to be a useful tool not only for protein separation but also for protein refolding. Furthermore, we found that a cyclic ligand carixarene has an extraction ability to set up optimum conditions for protein transfer. In the second topic, we have found that a supported liquid membrane (SLM) encapsulating enzymes shows high enantioselectivity (enantioselective excess value is over 96%) in the transport of racemic pharmaceutical compound ibuprofen. A different experiment also suggests that the α-chymotrypsin-catalyzed reactions droved the enantioselective transport of L-phenylalanine based on the enantioselectivity of the enzyme. The SLM encapsulating the surfactant-enzyme complex enabled the highly enantioselective separation of racemic mixtures. It can be envisioned that arrangement of appropriate enzymes in the SLM system will allow enantioselective separation of various useful organic compounds.

  7. Separation of some chiral flavanones by micellar electrokinetic chromatography.

    Science.gov (United States)

    Asztemborska, Monika; Miśkiewicz, Magdalena; Sybilska, Danuta

    2003-08-01

    Micellar electrokinetic chromatography (MEKC) was applied for enantioseparation of selected flavanones, including naringin, hesperidin, neohesperidin, naringenin, hesperetin, pinostrobin, isosakuranetin, eriodictyol, and homoeriodictyol. gamma-Cyclodextrin (gamma-CD) and sodium cholate (SCh) were used as chiral modifiers inducing enantioselectivity to the background electrolyte. From among many investigated selectors only these two appeared to possess the best enantioselective properties in respect to studied flavanones. The mechanisms of their action are a little different; SCh used above critical micelle point concentration forms chiral micelles itself while gamma-CD is deprived of this property and requires addition of surfactants as, e.g., sodium dodecyl sulfate. It was found that SCh enables separation of flavanone glycosides diastereomers while separation of enantiomers of flavanone aglycones may be achieved with gamma-CD. Consideration of structural relation led to the suggestion that interaction of sugar moiety of glycosides with SCh micelles give rise to chiral recognition. MEKC appeared to be a suitable and efficient analytical tool to follow enantiomeric composition of flavanones. PMID:12900864

  8. Quark Mass Correction to Chiral Separation Effect and Pseudoscalar Condensate

    CERN Document Server

    Guo, Er-dong

    2016-01-01

    We derived an analytic structure of the quark mass correction to chiral separation effect (CSE) in small mass regime. We confirmed this structure by a D3/D7 holographic model study in a finite density, finite magnetic field background. The quark mass correction to CSE can be related to correlators of pseudo-scalar condensate, quark number density and quark condensate in static limit. We found scaling relations of these correlators with spatial momentum in the small momentum regime. They characterize medium responses to electric field, inhomogeneous quark mass and chiral shift. Beyond the small momentum regime, we found existence of normalizable mode, which possibly leads to formation of spiral phase. The normalizable mode exists beyond a critical magnetic field, whose magnitude decreases with quark chemical potential.

  9. On the chiral separation effect in a slab

    CERN Document Server

    Sitenko, Yu A

    2016-01-01

    We study an influence of boundaries on chiral effects in hot dense relativistic spinor matter in a strong magnetic field which is transverse to bounding planes. The most general set of boundary conditions ensuring the confinement of matter within the bounding planes is considered. We find that, in thermal equilibrium, the nondissipative axial current along the magnetic field is induced, depending on chemical potential and temperature, as well as on a choice of boundary conditions. As temperature increases from zero to large values, a stepwise behaviour of the axial current density as a function of chemical potential is changed to a smooth one; the choice of a boundary condition can facilitate either amplification or diminution of the chiral separation effect. This points at a significant role of boundaries for physical systems with hot dense magnetized relativistic spinor matter, e.g., compact stars, heavy-ion collisions, novel materials known as Dirac and Weyl semimetals.

  10. [Synthesis and applications of chiral metal-organic framework in the selective separation of enantiomers].

    Science.gov (United States)

    Qi, Xiaoyue; Li, Xianjiang; Bai, Yu; Liu, Huwei

    2016-01-01

    Chirality is a universal phenomenon in nature. Chiral separation is vitally important in drug development, agricultural chemistry, pharmacology, environmental science, biology and many other fields. Chiral metal-organic frameworks (MOFs) are a new group of porous materials with special topology and designable pore structures, as well as their high specific surface area, porosity, excellent thermal stability, solvent resistance, etc. Thus, chiral MOFs are promising with various applications in the field of analytical chemistry. This review summarizes the synthesis strategies of chiral MOFs and their applications in the selective separation of enantiomers, as well as related mechanism.

  11. Chiral Separation of Basic Compounds on Sulfated β-Cyclodextrin-Coated Zirconia Monolith by Capillary Electrochromatography

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jongseong; Park, Jung Hag [Yeungnam Univ., Gyeongsan (Korea, Republic of)

    2013-06-15

    Sulfated β-cyclodextrin (SCD)-coated zirconia monolith was used as the chiral stationary phase in capillary electrochromatography for enantiomeric separation of basic chiral compounds. SCD adsorbed on the zirconia surface provided a stable chiral stationary phase in reversed-phase eluent. Retention, chiral selectivity and resolution of a set of six basic chiral compounds were measured in eluent of varying pH, composition of methanol and buffer. Optimum mobile phase condition for the separation of the compounds was found to be methanol content of 30%, buffer concentration of 30 mM and pH of 4.0.

  12. Separation and Structure of Chiral S—Malic Acid Hydrate

    Institute of Scientific and Technical Information of China (English)

    NIE,Jing-Jing; WU,Jing-Yun; 等

    2002-01-01

    Crystals of the chiral malic acid hydrate (C4H6O5·H2O) were unexpectedly obtained from an ethanol/water solution containing racemic D,L-malic acid and L-asparagine.The crystal belongs to orthorhombic space group P212121 with cell dimensions of a=0.5576(1),b=0.9818(2),c=1.1793(2)nm,V=0.6455(2)nm3,Z=4,μ(Mo Kα)=0.152mm-1,F(000)=320,Dc=1.565g·cm-3,R=0.051,wR=0.136 for 657 observed reflections [I>2σ(I)].The significant difference in bond distances for carboxyl groups suggests that the crystal consist of malate anion and protonized crystalline water.This is a report for direct separation of racemic mixture,i.e.,whthout the formation of a molecular complex of raceme with a chiral separating reagent.

  13. Separation and Structure of Chiral S-Malic Acid Hydrate

    Institute of Scientific and Technical Information of China (English)

    NIE,Jing-Jing(聂晶晶); XU,Duan-Jun(徐端钧); WU,Jing-Yun(吴景云); CHIANG,Michael Y.(蒋燕南)

    2002-01-01

    Crystals of the chiral malic acid hydrate ( C4H6O5@H2O ) were unexpectedly obtained from an ethanol ethanol/water solution containing racemic D,L-malic acid and L-asparagine. The crystal belongs to orthorhombic space group P21 21 21 with cell dimensions of a=0.5576(1), b=0.9818(2), c=1.1793(2) nm, V=0.9455(2) nm3, Z=4, μ(Mo Kα) =0.152 mm-1, F(000) =320, Dc= 1.565 g@cm-3, R =0.051, wR =0.136 for 657 observed reflections [I>2σ(I)]. The significant difference in bond distances for carboxyl groups suggests that the crystal consist of malate anion and protonized crystalline water. This is a report for direct separation of racemic mixture, i.e., without the formation of a molecular complex of raceme with a chiral separating reagent.

  14. The chiral separation and enantioselective degradation of the chiral herbicide napropamide.

    Science.gov (United States)

    Qi, Yanli; Liu, Donghui; Sun, Mingjing; Di, Shanshan; Wang, Peng; Zhou, Zhiqiang

    2014-02-01

    The chiral pesticide enantiomers often have different toxic effects and environmental behaviors, which suggests that the risk assessments should be on an enantiomeric level. In this work, the chiral separation of the napropamide enantiomers and the stereoselective degradation in tomato, cucumber, rape, cabbage, and soil were investigated. Napropamide enantiomers could be separated absolutely by high-performance liquid chromatography (HPLC) using a Chiralpak IC column with a resolution factor of 11.75 under the optimized condition. Solid phase extraction (SPE) was used for cleanup of the enantiomers in the vegetable samples. The residue analysis method was validated. Good linearities (R(2)  = 0.9997) and recoveries (71.43% -97.64%) were obtained. The limits of detection (LOD) were 0.05 mg/kg in soil and 0.20 mg/kg in vegetables. The results of degradation showed that napropamide dissipated rapidly in vegetables with half-lives of only 1.13-2.21 days, but much more slowly in soil, with a half-life of 11.95 d. Slight stereoselective degradation of the two enantiomers was only observed in cabbage, with enantiomeric fraction (EF) = 0.46, and there was no enantioselectivity in the other vegetables. The degradation of napropamide in the five matrixes was fast, and there was no enantioselectivity. PMID:24436218

  15. Chiral Separation by Flows: The Role of Flow Symmetry and Dimensionality

    Science.gov (United States)

    Ro, Sunghan; Yi, Juyeon; Kim, Yong Woon

    2016-01-01

    Separation of enantiomers by flows is a promising chiral resolution method using cost-effective microfluidics. Notwithstanding a number of experimental and numerical studies, a fundamental understanding still remains elusive, and an important question as to whether it is possible to specify common physical properties of flows that induce separation has not been addressed. Here, we study the separation of rigid chiral objects of an arbitrary shape induced by a linear flow field at low Reynolds numbers. Based on a symmetry property under parity inversion, we show that the rate-of-strain field is essential to drift the objects in opposite directions according to chirality. From eigenmode analysis, we also derive an analytic expression for the separation conditions which shows that the flow field should be quasi-two-dimensional for the precise and efficient resolutions of microscopic enantiomers. We demonstrate this prediction by Langevin dynamics simulations with hydrodynamic interactions fully implemented. Finally, we discuss the practical feasibility of the linear flow analysis, considering separations by a vortex flow or an extensional flow under a confining potential. PMID:27739430

  16. Synthesis of chiral dopants based on carbohydrates.

    Science.gov (United States)

    Tsuruta, Toru; Koyama, Tetsuo; Yasutake, Mikio; Hatano, Ken; Matsuoka, Koji

    2014-07-01

    Chiral dopants based on carbohydrates for nematic liquid crystals were synthesized from D-glucose, and their helical twisting power (HTP) values were evaluated. The chiral dopants induced helices in the host nematic liquid crystals. An acetyl derivative having an ether-type glycosidic linkage between carbohydrate and a mesogenic moiety showed the highest HTP value of 10.4 μm(-1), while an acetyl derivative having an anomeric ester-type linkage did not show any HTP. It was surprising that this molecule had no HTP despite the presence of chirality in the molecule. A relationship between HTP and specific rotation was not observed in this study.

  17. Chiral Separation of Ibuprofen and Terbutaline by Nonaqueous Capillary Electrophoresis with Conductance Detection

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In the nonaqueous N,N-dimethylformamide medium, the chiral drugs ibuprofen and terbutaline were successfully separated with sulfonyl-β-cyclodextrin(s-β-CD) as the chiral selector by capillary electrophoresis with conductance detection. The comparison of the effects of three CDS(β-CD, diethylic-β-CD, sulfonyl-β-CD) on the chiral separation was made and the resolution mechanism was proposed.

  18. Chiral separation of racemic drugs using molecular imprinting

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

  19. Chiral separation of the clinically important compounds fucose and pipecolic acid using CE: determination of the most effective chiral selector.

    Science.gov (United States)

    Hadjistasi, Christoforos A; Stavrou, Ioannis J; Stefan-Van Staden, Raluca-Ioana; Aboul-Enein, Hassan Y; Kapnissi-Christodoulou, Constantina P

    2013-09-01

    In this study, simple electrophoretic methods were developed for the chiral separation of the clinically important compounds fucose and pipecolic acid. In recent years, these analytes, and particularly their individual enantiomers, have attracted considerable attention due to their role in biological functions and disorders. The detectability and sensitivity of pipecolic acid and fucose were improved by reacting them with fluorenylmethyloxycarbonyl chloride (FMOC-Cl) and 5-amino-2-naphthalene-sulfonic acid (ANSA), respectively. The enantioseparation conditions were optimized by initially investigating the type of the chiral selector. Different chiral selectors, such as polymeric surfactants and cyclodextrins, were used and the most effective ones were determined with regard to resolution and analysis time. A 10-mM β-cyclodextrin was able to separate the enantiomers of ANSA-DL-fucose and the polymeric surfactant poly(sodium N-undecanoyl-LL-leucine-valinate) was able to separate the enantiomers of FMOC-DL-pipecolic acid, with resolution values of 3.45 and 2.78, respectively. Additional parameters, such as the concentration and the pH of the background electrolyte (BGE), the concentration of the chiral selector, and the addition of modifiers were examined in order to optimize the separations. The addition of the chiral ionic liquid D-alanine tert-butyl ester lactate into the BGE was also investigated, for the first time, in order to improve resolution of the enantiomers.

  20. Chiral separation of the clinically important compounds fucose and pipecolic acid using CE: determination of the most effective chiral selector.

    Science.gov (United States)

    Hadjistasi, Christoforos A; Stavrou, Ioannis J; Stefan-Van Staden, Raluca-Ioana; Aboul-Enein, Hassan Y; Kapnissi-Christodoulou, Constantina P

    2013-09-01

    In this study, simple electrophoretic methods were developed for the chiral separation of the clinically important compounds fucose and pipecolic acid. In recent years, these analytes, and particularly their individual enantiomers, have attracted considerable attention due to their role in biological functions and disorders. The detectability and sensitivity of pipecolic acid and fucose were improved by reacting them with fluorenylmethyloxycarbonyl chloride (FMOC-Cl) and 5-amino-2-naphthalene-sulfonic acid (ANSA), respectively. The enantioseparation conditions were optimized by initially investigating the type of the chiral selector. Different chiral selectors, such as polymeric surfactants and cyclodextrins, were used and the most effective ones were determined with regard to resolution and analysis time. A 10-mM β-cyclodextrin was able to separate the enantiomers of ANSA-DL-fucose and the polymeric surfactant poly(sodium N-undecanoyl-LL-leucine-valinate) was able to separate the enantiomers of FMOC-DL-pipecolic acid, with resolution values of 3.45 and 2.78, respectively. Additional parameters, such as the concentration and the pH of the background electrolyte (BGE), the concentration of the chiral selector, and the addition of modifiers were examined in order to optimize the separations. The addition of the chiral ionic liquid D-alanine tert-butyl ester lactate into the BGE was also investigated, for the first time, in order to improve resolution of the enantiomers. PMID:23757267

  1. Chiral Separation of Spiro-compounds and Determination Configuration

    Institute of Scientific and Technical Information of China (English)

    LIANG Ya; GUO Jing-jing; LIU Xiu-ming; WEI Rong-bao

    2008-01-01

    Chiral spirocyclic compounds have attracted the attention of scholars and scientists owing to their potential applications in the pharmaceutical industry as either active pharmaceutical ingredients,catalysts in synthesizing active enantiomers,or as surface modifiers on silica particles to resolve entantiomers,In this study,five spiro compounds of 3,9-diphenyl-2,4,8,10-tetraoxaspiro[5.5]-undecane(1),3,9-(4-methoxyphenyl)-2,4,8,10-tetraoxaspiro[5.5]-undecane(2),3,9-(4-methylphenyl)-2,4,8,10-tetraoxaspiro[5.5]-undecane(3),4,4'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dibenzoie acid(4) and 3,9-di(4-formyl-phenyl)-2,4,8,10-tetraoxa-spiro[5.5]-undecane(5) were synthesized by grinding pentaerythritol with benzaldehyde,4-methoxybenzaldehyde,4-methylbenzaldehyde,4-carboxybenzaldehyde or terephthalaldehyde monoacetal in the presence of InBr3 under solvent-free conditions,A normal phase HPLC method was successfully developed to resolve entantiomers of compounds 1-5 on a chiral column,Specific optical rotation of R or S entantiomers(1) was determined and the corresponding configurations were proposed based on Lowe's rule.

  2. Chiral separation by enantioselective liquid-liquid extraction.

    Science.gov (United States)

    Schuur, Boelo; Verkuijl, Bastiaan J V; Minnaard, Adriaan J; de Vries, Johannes G; Heeres, Hero J; Feringa, Ben L

    2011-01-01

    The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and chemical engineers in the fields of fine chemicals, pharmaceuticals, agrochemicals, fragrances and foods. In this review the principles and advances of resolution through enantioselective liquid-liquid extraction are discussed, starting with an introduction on the principles of enantioselective liquid-liquid extraction including host-guest chemistry, extraction and phase transfer mechanisms, and multistage liquid-liquid extraction processing. Then the literature on enantioselective liquid-liquid extraction systems is reviewed, structured on extractant classes. The following extractant classes are considered: crown ether based extractants, metal complexes and metalloids, extractants based on tartrates, and a final section with all other types of chiral extractants. PMID:21107491

  3. Application of cinchona-sulfonate-based chiral zwitterionic ion exchangers for the separation of proline-containing dipeptide rotamers and determination of on-column isomerization parameters from dynamic elution profiles

    Energy Technology Data Exchange (ETDEWEB)

    Wernisch, Stefanie, E-mail: stefanie.wernisch@univie.ac.at [Institute for Analytical Chemistry, University of Vienna, Währinger Straße 38, A-1090 Vienna (Austria); Trapp, Oliver, E-mail: trapp@oci.uni-heidelberg.de [Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg (Germany); Lindner, Wolfgang, E-mail: wolfgang.lindner@univie.ac.at [Institute for Analytical Chemistry, University of Vienna, Währinger Straße 38, A-1090 Vienna (Austria)

    2013-09-17

    Graphical abstract: -- Highlights: •X-Pro peptides produce interconverting elution profiles on zwitterionic stationary phases. •The cis–trans isomerization rate in solution is lower than in the chromatographic system. •Cinchona-based zwitterionic selectors apparently lower the isomerization barrier. •Rotamer separation is feasible <0 °C, enantiomer separation above room temperature. -- Abstract: The interconversion of cis and trans isomers of dipeptides containing C-terminal proline was studied by dynamic chromatography on zwitterionic chiral stationary phases at temperatures ranging from −15 °C to +45 °C The cis–trans isomers could be separated below 0 °C and above 0–10 °C plateau formation and peak coalescence phenomena occurred, which is characteristic for a dynamic process at the time-scale of partitioning. At and above room temperature, full coalescence was observed, which allowed separations of enantiomers without interference from interconversion effects. Analysis of the dynamic elution profiles of the interconverting peptides allowed the determination of isomerization rate constants and thermodynamic activation parameters (isomerization enthalpy, entropy and activation energy). In accordance with established results, isomerization rates and thermodynamic parameters were found to depend on the nature of the N-terminal amino acid. Isomerization barriers were only slightly lower than values determined with other methods but significant differences in the relative contributions of the activation enthalpy and entropy as well as isomerization rates pointed toward selector-moderated isomerization dynamics.

  4. Application of High Performance Liquid Chromatography to Separation of Novel Chiral Tetrahedral Heterometal Clusters

    Institute of Scientific and Technical Information of China (English)

    Xin Yi ZHU; Wei Qiang ZHANG; Yu Hua ZHANG; Li Ren CHEN; Yong Min LI

    2003-01-01

    A series of novel chiral tetrahedral heterometal clusters have firstly been separated oncellulose tris-(3,5-dimethylphenylcarbamate) stationary phase by high performance liquid chrom-atography, using hexane as the mobile phase with various alcohols as modifiers.

  5. Chiral HPLC Separation and Modeling of Four Stereomers of DL-Leucine-DL-Tryptophan Dipeptide on Amylose Chiral Column.

    Science.gov (United States)

    Alajmi, Mohammed F; Hussain, Afzal; Suhail, Mohd; Mukhtar, Sofi Danish; Sahoo, Dibya Ranjan; Asnin, Leonid; Ali, Imran

    2016-09-01

    Chiral high-performance liquid chromatography (HPLC) separation and modeling of four stereomers of DL-leucine-tryptophan DL-dipeptide on AmyCoat-RP column are described. The mobile phase applied was ammonium acetate (10 mM)-methanol-acetonitrile (50:5:45, v/v). The flow rate of the mobile phases was 0.8 mL/min with UV detection at 230 nm. The values of retention factors for LL-, DD-, DL-, and LD- stereomers were 2.25, 3.60, 5.00, and 6.50, respectively. The values of separation and resolution factors were 1.60, 1.39, and 1.30 and 7.76, 8.05, and 7.19. The limits of detection and quantitation were ranging from 1.0-2.3 and 5.6-14.0 μg/mL. The simulation studies established the elution orders and the mechanism of chiral recognition. It was seen that π-π connections and hydrogen bondings were the main forces for enantiomeric resolution. The reported chiral HPLC method may be applied for the enantiomeric separation of DL-leucine-DL-tryptophan in unknown matrices. Chirality 28:642-648, 2016. © 2016 Wiley Periodicals, Inc. PMID:27474783

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

    Science.gov (United States)

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

    2014-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Sha Yang

    2016-06-01

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

  8. 信息动态%Preparation of Polysaccharide Derivatives-based Composite Chiral Stationary Phases and Their Chiral Recognition

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Two coated-type composite chiral stationary phases (CSPs) were prepared based on cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) and amylose tris (3,5-dimethylphenylcarbamate)(ADMPC) by coating the corresponding derivatives onto 3-aminopropyl silica gel separately and then mixing or by coating the mixed derivatives onto silica gel. The CSPs containing only CDMPC or ADMPC were also prepared for comparison. The mixing method does not significantly influence the enantioselectivities. The composite CSPs generally show chiral recognition abilities intermediate between those of the two individual phases, while some racemates were poorer and at the same time one was better resolved on the composite CSPs.

  9. Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases.

    Science.gov (United States)

    Huang, Xu-Guang

    2016-01-01

    The chiral magnetic and chiral separation effects-quantum-anomaly-induced electric current and chiral current along an external magnetic field in parity-odd quark-gluon plasma-have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects. PMID:26868084

  10. Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

    OpenAIRE

    Xu-Guang Huang

    2016-01-01

    The chiral magnetic and chiral separation effects---quantum-anomaly-induced electric current and chiral current along an external magnetic field in parity-odd quark-gluon plasma---have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud alon...

  11. Chiral Separation by Capillary Zone Electrophoresis Used Cyclodextrins and Their Derivatives as Chiral Selector

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Capillary zone electrophoresis (CZE) is a very pronising analytical technique for the optical isomer resolution of the compounds studied. The drawbacks of the techniques such as HPLC [1] were sophisticated stationary phases and/or the relatively high quantity of the chiral agent in the mobile phase, which do not exist in CZE. The capillary electrophoresis (CE) method can offer advantages on lower consumption of analyte and background electrolyte (BGE), shorter analysis time, and higher efficiencies [2-3

  12. 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.

  13. 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. PMID:27240968

  14. [Capillary electrochromatography for chiral separation and purity testing of pharmaceutical drug substances].

    Science.gov (United States)

    Gazdag, Mária; Takács, Tímea; Szóllósi, Eva

    2003-01-01

    Chiral separation of D,L-Norgestrel was successfully performed by cyclodextrin-modified capillary electrochromatographic (CEC) method. Optimized CEC conditions for purity testing were achieved: Hypersil C-18 packed capillary and 10 mM 2-[N-morpholino]-ethanesulfonic acid buffer (MES) and 40 v/v % methanol as background electrolyte containing 10 mM gamma-cyclodextrin at pH = 5.5. The resolution was found to be strongly dependent on the concentration of chiral selector gamma-cyclodextrin, applied voltage and temperature of the capillary. Our results represent a simple, fast and reproducible method for the separation of D,L-Norgestrel and purity testing of D-Norgestrel. It can be concluded that cyclodextrin modified HPLC, HPCE and CEC offer inexpensive, attractive and reliable chiral separation methods.

  15. In search of chiral magnetic effect: separating flow-driven background effects and quantifying anomaly-induced charge separations

    CERN Document Server

    Huang, Xu-Guang; Liao, Jinfeng

    2015-01-01

    We report our recent progress on the search of Chiral Magnetic Effect (CME) by developing new measurements as well as by hydrodynamic simulations of CME and background effects, with both approaches addressing the pressing issue of separating flow-driven background contributions and possible CME signal in current heavy ion collision measurements.

  16. Elastic properties of chiral, anti-chiral, and hierarchical honeycombs: A simple energy-based approach

    Directory of Open Access Journals (Sweden)

    Davood Mousanezhad

    2016-03-01

    Full Text Available The effects of two geometric refinement strategies widespread in natural structures, chirality and self-similar hierarchy, on the in-plane elastic response of two-dimensional honeycombs were studied systematically. Simple closed-form expressions were derived for the elastic moduli of several chiral, anti-chiral, and hierarchical honeycombs with hexagon and square based networks. Finite element analysis was employed to validate the analytical estimates of the elastic moduli. The results were also compared with the numerical and experimental data available in the literature. We found that introducing a hierarchical refinement increases the Young’s modulus of hexagon based honeycombs while decreases their shear modulus. For square based honeycombs, hierarchy increases the shear modulus while decreasing their Young’s modulus. Introducing chirality was shown to always decrease the Young’s modulus and Poisson’s ratio of the structure. However, chirality remains the only route to auxeticity. In particular, we found that anti-tetra-chiral structures were capable of simultaneously exhibiting anisotropy, auxeticity, and remarkably low shear modulus as the magnitude of the chirality of the unit cell increases.

  17. Chiral Separation by Capillary Zone Electrophoresis Used Cyclodextrins and Their Derivatives as Chiral Selector

    Institute of Scientific and Technical Information of China (English)

    HOU; JingGuo

    2001-01-01

    Capillary zone electrophoresis (CZE) is a very pronising analytical technique for the optical isomer resolution of the compounds studied. The drawbacks of the techniques such as HPLC [1] were sophisticated stationary phases and/or the relatively high quantity of the chiral agent in the mobile phase, which do not exist in CZE. The capillary electrophoresis (CE) method can offer advantages on lower consumption of analyte and background electrolyte (BGE), shorter analysis time, and higher efficiencies [2-3]  ……

  18. Hydrodynamics with chiral anomaly and charge separation in relativistic heavy ion collisions

    CERN Document Server

    Yin, Yi

    2015-01-01

    Matter with chiral fermions is microscopically described by theory with quantum anomaly and macroscopically described (at low energy) by anomalous hydrodynamics. For such systems in the presence of external magnetic field and chirality imbalance, a charge current is generated along the magnetic field direction --- a phenomenon known as the Chiral Magnetic Effect (CME). The quark-gluon plasma created in relativistic heavy ion collisions provides an (approximate) example, for which the CME predicts a charge separation perpendicular to the collisional reaction plane. Charge correlation measurements designed for the search of such signal have been done at RHIC and the LHC for which the interpretations, however, remain unclear due to contamination by background effects that are collective flow driven, theoretically poorly constrained, and experimentally hard to separate. Using anomalous (and viscous) hydrodynamic simulations, we make a first attempt at quantifying contributions to observed charge correlations from...

  19. Chiral separation of hesperidin and naringin and its analysis in a butanol extract of Launeae arborescens.

    Science.gov (United States)

    Belboukhari, Nasser; Cheriti, Abdelkrim; Roussel, Christian; Vanthuyne, Nicolas

    2010-04-01

    Two flavanone glycosides were isolated from the aerial part of Launeae arborescens (Asteraceae), which were identified as hesperidin and naringin. They are the most abundant flavonoids in the edible parts of many species of citrus fruits. In this study, we were interested in the chiral separation and determination of the diastereomerisation barriers of hesperidin and naringin by HPLC methods. The chiral separation HPLC screening of diastereomers of hesperidin and naringin by HPLC methods was accomplished in the normal-phase mode using 11 chiral stationary phases and various n-hexane/alcohol mobile phases. The rate constants and activation energy of diastereomerisation (DeltaG#) of flavanones, naringin and hesperidin were determined, respectively, on Chiralpak IC and Chiralpak IA. The analysis of flavanones isolated in butanol extracts of Launeae arborescens were confirmed by HPLC on Chiralpak IC. PMID:20401799

  20. Enantiomeric Separations of Pyriproxyfen and its Six Chiral Metabolites by High-Performance Liquid Chromatography.

    Science.gov (United States)

    Zhang, Chuntao; Liu, Hui; Liu, Donghui; Wang, Liying; Gao, Jing; Zhou, Zhiqiang; Wang, Peng

    2016-03-01

    Pyriproxyfen is a chiral insecticide, and over 10 metabolites have been identified in the environment. In this work the separations of the enantiomers of pyriproxyfen and its six chiral metabolites were studied by high-performance liquid chromatography (HPLC). Both normal phase and reverse phase were applied using the chiral columns Chiralpak IA, Chiralpak IB, Chiralpak IC, Chiralcel OD, Chiralcel OD-RH, Chiralpak AY-H, Chiralpak AD-H, Chiracel OJ-H, (R,R)-Whelk-O 1, and Lux Cellulose-3. The effects of the chromatographic parameters such as mobile phase composition and temperature on the separations were investigated and the enantiomers were identified with an optical rotation detector. The enantiomers of these targets could obtain complete separations (resolution factor Rs > 1.5) on Chiralpak IA, Chiralpak IB, Chiralcel OD, Chiralpak AY-H, or Chiracel OJ-H under normal conditions. Chiralcel OJ-H showed the best chiral separation results with n-hexane as mobile phase and isopropanol (IPA) as modifier. The simultaneous enantiomeric separation of pyriproxyfen and four chiral metabolites was achieved on Chiralcel OJ-H under optimized condition: n-hexane/isopropanol = 80/20, 15°C, flow rate of 0.8 ml/min, and UV detection at 230 nm. The enantiomers of pyriproxyfen and the metabolites , , and obtained complete separations on Chiralpak IA, Chiralpak IC, and Lux Cellulose-3 under reverse phase using acetonitrile/water as the mobile phase. The retention factors (k) and selectivity factors (α) decreased with increasing temperature, and the separations were better under low temperature in most cases. The work is of significance for the investigation of the environmental behaviors of pyriproxyfen on an enantiomeric level.

  1. Enantiomeric Separations of Pyriproxyfen and its Six Chiral Metabolites by High-Performance Liquid Chromatography.

    Science.gov (United States)

    Zhang, Chuntao; Liu, Hui; Liu, Donghui; Wang, Liying; Gao, Jing; Zhou, Zhiqiang; Wang, Peng

    2016-03-01

    Pyriproxyfen is a chiral insecticide, and over 10 metabolites have been identified in the environment. In this work the separations of the enantiomers of pyriproxyfen and its six chiral metabolites were studied by high-performance liquid chromatography (HPLC). Both normal phase and reverse phase were applied using the chiral columns Chiralpak IA, Chiralpak IB, Chiralpak IC, Chiralcel OD, Chiralcel OD-RH, Chiralpak AY-H, Chiralpak AD-H, Chiracel OJ-H, (R,R)-Whelk-O 1, and Lux Cellulose-3. The effects of the chromatographic parameters such as mobile phase composition and temperature on the separations were investigated and the enantiomers were identified with an optical rotation detector. The enantiomers of these targets could obtain complete separations (resolution factor Rs > 1.5) on Chiralpak IA, Chiralpak IB, Chiralcel OD, Chiralpak AY-H, or Chiracel OJ-H under normal conditions. Chiralcel OJ-H showed the best chiral separation results with n-hexane as mobile phase and isopropanol (IPA) as modifier. The simultaneous enantiomeric separation of pyriproxyfen and four chiral metabolites was achieved on Chiralcel OJ-H under optimized condition: n-hexane/isopropanol = 80/20, 15°C, flow rate of 0.8 ml/min, and UV detection at 230 nm. The enantiomers of pyriproxyfen and the metabolites , , and obtained complete separations on Chiralpak IA, Chiralpak IC, and Lux Cellulose-3 under reverse phase using acetonitrile/water as the mobile phase. The retention factors (k) and selectivity factors (α) decreased with increasing temperature, and the separations were better under low temperature in most cases. The work is of significance for the investigation of the environmental behaviors of pyriproxyfen on an enantiomeric level. PMID:26773961

  2. Chiral separation of non-steroidal anti-inflammatory drugs by preparative and simulated moving bed chromatography

    OpenAIRE

    Ribeiro, António E.; Gomes, Pedro Sá; Pais, L.S.; A.E. Rodrigues

    2011-01-01

    The work presents modelling, simulation and experimental results for the chiral separation of non-steroidal anti-inflammatory drugs, particularly, the optimization of mobile phase composition under preparative and simulated moving bed chromatography. The experimental separation of two chiral systems (ketoprofen and flurbiprofen enantiomers) will be presented to show how compounds of the same family can lead to different solutions.

  3. Separation of flow from chiral magnetic effect in U+U collisions using spectator asymmetry

    CERN Document Server

    Chatterjee, Sandeep

    2014-01-01

    We demonstrate that the prolate shape of the Uranium nucleus generates anti-correlation between spectator asymmetry and initial state ellipticity of the collision zone, providing a way to constrain the initial event shape in U+U collisions. As an application, we show that this can be used to separate the background contribution due to flow from the signals of chiral magnetic effect.

  4. A Study on Microgel System as a Template for Dispersion and Separation of Chiral Tartaric Acid

    Directory of Open Access Journals (Sweden)

    Azwan Mat Lazim

    2012-07-01

    Full Text Available Separation of tartaric acid enantiomers in organic compounds using conventional techniques requires high energy demand, high chemicals consumption, lengthy, complicated and expensive processes. This research demonstrates utilization of PNIPAM microgel system as a template for incorporation of chiral D- and L- tartaric acids (TA. The poly(n-isopropylacrylamide (PNIPAM microgel was synthesized using surfactant free emulsion polymerization (SFEP and was characterized using standard procedures. The combination of 1.4×10-3 g/ml microgel with 3.02×10-4 g/ml TA gave the most stable system. Subsequently, a two-phase system was obtained after centrifugation. Both phases were subjected to dynamic light scattering (DLS analysis and the corresponding separated systems gave particle sizes ranging from 80-90 nm for the upper phase, and 1200-1500 nm for the lower phase. Scanning electron micrographs showed the presence of agglomeration in the lower phase, supporting the DLS results. Nuclear magnetic resonance (1H NMR analysis confirmed the presence of TA indicated by a peak at δ = 13.1 ppm. Based on these findings, the system can be a potential alternative template for TA racemix acid dispersion and separation.

  5. Synthesis of Chiral Metal Complexes of Unsymmetrical Schiff Bases

    Institute of Scientific and Technical Information of China (English)

    SONG; Bo

    2001-01-01

    Recently, in asymmetric catalyst research the great developments of chiral Salen complexes have been made, but the report on unsymmetrical schiff bases is deficient. The unsymmetrical schiff bases complexes are an effective system in catalytically selective Olefin-epoxidations1. At the same time, unsymmetrical schiff bases was immobilized onto polymer supports for heterogenization2. The potential benefits of the catalyst include facilitation of catalyst separation from reagents, simplification of methods for catalyst recycle, and the possible adaptation of the immobilized catalyst to continuous-flow processes. A series of new unsymmetrical schiff bases was synthesized to study the relations between unsymmetry and enantioselectivity and select better catalyst. The following is the route:  ……

  6. Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    Dalkeun; PARK; Joong; Kee; LEE; 等

    2002-01-01

    Ibprofen is widely used as a non-steroidal anti-inflammatory drug and poduced as racemic mixture.Its pharmacological activity resides only is S-(+)-enantiomer,and R-(-)-enantiomer is not only inactive but also has many side effects.Thus it is necessary to separate Renantiomer from racemic ibuprofen.We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography(HPLC).,Out of three different chiral stationary phases,which were selected on the basis of structure and availability,two were found to be effective.There was optimum eluent composition for each stationary phase for good resolution in optical separation.Resolution decreased with increase of eluent flow rate,but effect of injection volume on resolution was insignificant at high eluent flow rate.

  7. Synthesis of novel chiral compounds of purine and pyrimidine bases

    Institute of Scientific and Technical Information of China (English)

    汪毓海; 陈庆华

    1999-01-01

    The physiologically active groups such as purine and pyrimidine bases are introduced to the asymmetric ynthesis. The optically pure compounds bearing purine and pyrimidine bases (5a—5e) were prepared via the asymetric Michael addition reaction of purines and pyrimidines as Michael donators with the chiral source 5-(R)-[(1R, 2S, 5R)-menthyloxy]-2(5H)-furanone (3a), which was prepared from the natural chiral auxiliary (-)-menthol. The synthetic method was studied in detail and the new compounds were identified on the basis of their analytical data and spectroscopic data, such as [α]D20, IR, UV, 1H NMR, 13C NMR and MS. The absolute configuration of 5a was established by X-ray crystallography. The results provided an efficient synthetic route to chiral purines and pyrimidine analogues, and offered chiral sources for further research on the physiologically active compounds of chiral nucleotides.

  8. Synthesis and Chiral Separation of Dinucleotide(TpAZT) Phosphoramidates

    Institute of Scientific and Technical Information of China (English)

    Chang Xue LIN; Hua FU; Guang Zhong TU; Yu Fen ZHAO

    2003-01-01

    Dinucleotide (TpAZT) phosphoramidates were synthesized by Todd reaction of dinucleoside H-phosphonates and amino acid methyl esters, and their diastereomers (Rp and Sp) were separated by crystallization, and the results showed that natural and cheap methyl esters of alanine and phenylalanine can be used for large-scale synthesis of dinucleotide analogs.

  9. The Role Seemingly of Amorphous Silica Gel Layers in Chiral Separations by Planar Chromatography

    Directory of Open Access Journals (Sweden)

    Teresa Kowalska

    2007-12-01

    Full Text Available In planar chromatography, silica gel appears as the most frequently used adsorbent. Its preference as planar chromatographic stationary phase is due to its high specific surface area (ca. 700 m2 g-1 and relatively simple active sites (silanol groups, Si-OH. The high specific surface area of silica gel and a high density of coverage of its surface with the silanol active sites contribute jointly to an excellent separation performance of this adsorbent. In our experiments on chiral separation of the enantiomer pairs by planar chromatography, contradictory behavior of the silica gel layers versus the chiral compounds was observed. The migration tracks of chiral compounds in the ascending planar chromatographic mode were not vertical but bent on either side being a function of analyte chirality. This deviation of the analyte’s migration track was noticed, when using the densitometric scanner to quantify the respective chromatograms. In order to confirm the hypothesis as to the microcrystalline nature of silica gel used in liquid chromatography, it was further investigated through circular dichroism (CD and the data thereof confirmed that the ‘chromatographic’ silica gels are not amorphous but microcrystalline, contributing to the (partial horizontal enantioseparation of the antimer pairs. This paper summarizes the results of our investigation on the microcrystalline nature of silica gels used in planar chromatography and their impact on enantioseparation of the selected pairs of antimers.

  10. Cyclodextrine Screening for the Chiral Separation of Amlodipine Enantiomers by Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Gabriel Hancu

    2015-03-01

    Full Text Available Purpose: Amlodipine is a long acting, dihydropyridine type calcium channel blocker frequently used in the treatment of hypertension and coronary insufficiency. The calcium channel blocking activity resides primarily in the S-amlodipine enantiomer, while R-amlodipine is a potent inhibitor of smooth muscle cell migration. Methods: In this study capillary electrophoresis was applied for the enantiomeric separation of amlodipine using different native and derivatized; neutral and charged cyclodextrines as chiral selectors. The effects of pH and composition of the background electrolyte, concentration and type of chiral selector, capillary temperature, running voltage and injection parameters have been investigated. Results: Stereoselective interactions were observed when using α-CD, β-CD, HP-β-CD, RAMEB, CM-β-CD and SBE-β-CD. Optimized separation conditions consisted on a 50 mM phosphate buffer, pH – 3.0, 20 mM RAMEB as chiral selector, + 25 kV applied voltage, 15°C temperature and UV detection at 238 nm. Using the optimized electrophoretic conditions we succeeded the chiral separation of amlodipine enantiomers in approximately 6 minute, the order of migration being R-amlodipine followed by S-amlodipine. The method was successfully applied for the determination of amlodipine enantiomers from commercially available pharmaceuticals. The linearity range, limits of detection and quantification, precision and accuracy were determined and the results obtained confirmed that the method was suitable for this purpose. Conclusion: It can be concluded that the proposed capillary electrophoresis methods can be useful for routine pharmaceutical applications with benefits of its effectivity, simplicity, short analysis time and low consumption of analytes, solvents and chiral selectors.

  11. Comparison of chiral electrophoretic separation methods for phenethylamines and application on impurity analysis.

    Science.gov (United States)

    Borst, Claudia; Holzgrabe, Ulrike

    2010-12-15

    A chiral microemulsion electrokinetic chromatography method has been developed for the separation of the enantiomers of the phenethylamines ephedrine, N-methylephedrine, norephedrine, pseudoephedrine, adrenaline (epinephrine), 2-amino-1-phenylethanol, diethylnorephedrine, and 2-(dibutylamino)-1-phenyl-1-propanol, respectively. The separations were achieved using an oil-in-water microemulsion consisting of the oil-component ethyl acetate, the surfactant sodium dodecylsulfate, the cosurfactant 1-butanol, the organic modifier propan-2-ol and 20mM phosphate buffer pH 2.5 as aqueous phase. For enantioseparation sulfated beta-cyclodextrin was added. The method was compared to an already described CZE method, which made use of heptakis(2,3-di-O-diacetyl-6-O-sulfo)-beta-cyclodextrin (HDAS) as chiral selector. Additionally, the developed method was successfully applied to the related substances analysis of noradrenaline, adrenaline, dipivefrine, ephedrine and pseudoephedrine monographed in the European Pharmacopoeia 6.

  12. Engineering Cyclodextrin Clicked Chiral Stationary Phase for High-Efficiency Enantiomer Separation

    Science.gov (United States)

    Tang, Jian; Zhang, Shapopeng; Lin, Yuzhou; Zhou, Jie; Pang, Limin; Nie, Xuemei; Zhou, Baojing; Tang, Weihua

    2015-08-01

    The separation of racemic molecules is of crucial significance not only for fundamental research but also for technical application. Enantiomers remain challenging to be separated owing to their identical physical and chemical properties in achiral environments. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers, most of which are of biological and pharmaceutical interests. Here we report our efforts in developing high-performance phenylcarbamated cyclodextrin (CD) clicked CSPs. Insights on the impact of CD functionalities in structure design are provided. High-efficiency enantioseparation of a range of aryl alcohols and flavanoids with resolution values (Rs) over 10 were demonstrated by per(3-chloro-4-methyl)phenylcarbamated CD clicked CSP. Comparison study and molecular simulations suggest the improved enantioselectivity was attributed to higher interactions energy difference between the complexes of enantiomers and CSPs with phenylcarbamated CD bearing 3-chloro and 4-methyl functionalities.

  13. Proton Spin Based On Chiral Dynamics

    OpenAIRE

    Weber, H. J.

    1999-01-01

    Chiral spin fraction models agree with the proton spin data only when the chiral quark-Goldstone boson couplings are pure spinflip. For axial-vector coupling from soft-pion physics this is true for massless quarks but not for constituent quarks. Axial-vector quark-Goldstone boson couplings with {\\bf constituent} quarks are found to be inconsistent with the proton spin data.

  14. Chiral separation of a diketopiperazine pheromone from marine diatoms using supercritical fluid chromatography.

    Science.gov (United States)

    Frenkel, Johannes; Wess, Carsten; Vyverman, Wim; Pohnert, Georg

    2014-03-01

    The proline derived diketopiperazine has been identified in plants, insects and fungi with unknown function and was recently also reported as the first pheromone from a diatom. Nevertheless the stereochemistry and enantiomeric excess of this natural product remained inaccessible using direct analytical methods. Here we introduce a chiral separation of this metabolite using supercritical fluid chromatography/mass spectrometry. Several chromatographic methods for chiral analysis of the diketopiperazine from the diatom Seminavis robusta and synthetic enantiomers have been evaluated but neither gas chromatography nor high performance liquid chromatography on different chiral cyclodextrin phases were successful in separating the enantiomers. In contrast, supercritical fluid chromatography achieved baseline separation within four minutes of run time using amylose tris(3,5-dimethylphenylcarbamate) as stationary phase and 2-propanol/CO2 as mobile phase. This very rapid chromatographic method in combination with ESI mass spectrometry allowed the direct analysis of the cyclic dipeptide out of the complex sea water matrix after SPE enrichment. The method could be used to determine the enantiomeric excess of freshly released pheromone and to follow the rapid degradation observed in diatom cultures. Initially only trace amounts of c(d-Pro-d-Pro) were found besides the dominant c(l-Pro-l-Pro) in the medium. However the enantiomeric excess decreased upon pheromone degradation within few hours indicating that a preferential conversion and thus inactivation of the l-proline derived natural product takes place.

  15. Hydroxypyridyl Imines: Enhancing Chromatographic Separation and Stereochemical Analysis of Chiral Amines via Circular Dichroism.

    Science.gov (United States)

    Joyce, Leo A; Regalado, Erik L; Welch, Christopher J

    2016-09-16

    Imine-bond formation between chiral amines and commercially available 3-hydroxypyridine-2-carboxaldehyde (HCA) was exploited for rapid determination of stereochemical composition. Chiral supercritical fluid chromatography (SFC) screening of the derivatized imine compounds led to the elucidation of multiple combinations of mobile and stationary phases that gave resolution of all members of a series of chiral amines. The first eluting enantiomer was generally the derivative of the (R)-amine enantiomer across the series that was studied, indicating that the imine formed from the (S)-amine has more favorable interaction with the chiral stationary phase of the column. These conditions were then applied to more challenging compounds, namely amino alcohols and diastereomers possessing more than one stereocenter. The approach was utilized to monitor stereoselective biocatalytic transamination and assign the absolute configuration of the enantiomeric products. Finally, hydrolysis of the imine bond of the derivative was shown to generate enantiopure amine starting materials without racemization. This further highlights the value of this approach for creating readily reversed derivatives that enhance chromatographic separation and aid in the determination of absolute configuration.

  16. Chiral Separation of Novel a-Aminophosphonates Containing a Benzothiazole Moiety by Liquid Chromatography Using an Amylose Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    LU Ping; ZHANG Yu-Ping; SONG Bao-An; YANG Song; BHADURY Shankar Pinaki; HU De-Yu; XUE Wei; CHEN Zhuo; JIN Lin-Hong

    2008-01-01

    The present report describes a chiral HPLC method for the enantiomeric separation of a-aminophosphonate derivatives using two new coated and immobilized amylose-based chiral stationary phases (CSP,Chiralpak IA and Chiralpak AD-H).The chromatographic parameters such as retention factor (k),separation factor (a),and resolution (Rs) of the solutes were investigated on these two CSPs.Reasonably good baseline separation for these compounds was achieved using Chiralpak IA column.The influences of temperature,content of ethanol modifier and the structure of analyte were also studied.THF,EtOAc and CH2Cl2 were used as ehients on analytical and semi-preparative columns.Highly enriched enantiomers with purities of up to 96.4%--100% (ee) and yields of 90.2%--95.5% were obtained,respectively.The proposed methods were found to be suitable and accurate for rapid separation and semi-preparation of enantiomeric a-aminophosphonate derivatives available.

  17. Application of an eremomycin-chiral stationary phase for the separation of DL-methionine using simulated moving bed technology.

    Science.gov (United States)

    Zhang, L; Gedicke, K; Kuznetsov, M A; Staroverov, S M; Seidel-Morgenstern, A

    2007-08-24

    Recently a new chiral stationary phase (CSP) was introduced, based on the immobilization of the macrocyclic glycopeptide eremomycin to epoxy-activated silica. The application of this new CSP to preparative enantioseparation using simulated moving bed (SMB) chromatography will be presented. MeOH-H(2)O (0.1M NaH(2)PO(4))=20/80 (v/v) was used as the mobile phase to separate the enantiomers of methionine. Successful separation was realized providing productivities around 15 g(product)/l(stat)/h for both l and d-methionine under nonlinear conditions. In such delicate continuous chromatographic separation processes, besides productivity, the long-term stability of the applied stationary phases is of importance. Column to column fluctuations were negligible and long-term stability of the preparative stationary phase was satisfactory according to the results of perturbation experiments performed before and after long-term SMB runs. PMID:17482626

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

    International Nuclear Information System (INIS)

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

  19. Experimental implementation of automatic 'cycle to cycle' control of a chiral simulated moving bed separation.

    Science.gov (United States)

    Amanullah, Mohammad; Grossmann, Cristian; Mazzotti, Marco; Morari, Manfred; Morbidelli, Massimo

    2007-09-21

    In the absence of a suitable controller, currently simulated moving beds (SMBs) are operated suboptimally to cope with system uncertainties and to guarantee robustness of operation. Recently, we have developed a 'cycle to cycle' optimizing controller that not only makes use of minimal system information, i.e. only the Henry constants and average bed voidage, but also optimizes the process performance and taps the full economic potential of the SMB technology. The experimental implementation of the 'cycle to cycle' optimizing controller had been carried out for achiral separation. For chiral separation however, application of any online controller has not been possible because an appropriate online monitoring system has not been available. This work reports and discusses the first experimental implementation of the 'cycle to cycle' optimizing control for chiral separations. A mixture of guaifenesin enantiomers is separated on Chiralcel OD columns with ethanol as mobile phase in a eight-column four sections laboratory SMB unit. The results show that the controller, although using minimal information about the retention of the two enantiomers, is able to meet product and process specifications, can optimize the process performance, and is capable of rejecting disturbances that may occur during the operation of the SMB plant. PMID:17707852

  20. Rapid chiral separation and impurity determination of levofloxacin by ligand-exchange chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Hongyuan [Center for Advanced Bioseparation Technology, Department of Chemical Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Row, Kyung Ho [Center for Advanced Bioseparation Technology, Department of Chemical Engineering, Inha University, Incheon 402-751 (Korea, Republic of)]. E-mail: rowkho@inha.ac.kr

    2007-02-12

    A sensitive, simple, and accurate method for determination of levofloxacin and its (R)-enantiomer was developed to determine the chiral impurity of levofloxacin in Cravit Tablets material by ligand-exchange high performance liquid chromatography. The effects of different kinds of ligands, concentration of ligands in mobile phase, organic modifier, pH of mobile phase, and temperature on enantioseparation were investigated and evaluated. Chiral separation was performed on a conventional C{sub 18} column, where the mobile phase consisted of a methanol-water solution (containing10 mmol L{sup -1} L-leucine and 5 mmol L{sup -1} copper sulfate) (88:12, v/v) and its flow-rate was set at 1.0 mL min{sup -1}. The conventional C{sub 18} column offers baseline separation of two enantiomers with a resolution of 2.4 in less than 20 min. Thermodynamic data ({delta}{delta}H and {delta}{delta}S) obtained by Van't Hoff plots revealed the chiral separation is an enthalpy-controlled process. The standard curves showed excellent linearity over the concentration range from 0.5 to 400 mg L{sup -1} for levofloxacin and its (R)-enantiomer. The linear correlation equations are: y = 1.33 x 10{sup 5} x + 6297 (r = 0.9991) and y = 1.34 x 10{sup 5} x + 3565 (r = 0.9997), respectively. The relative standard deviation (RSD) of the method was below 2.3% (n = 3)

  1. Pasteur's Experiment Performed at the Nanoscale: Manual Separation of Chiral Molecules, One by One.

    Science.gov (United States)

    Ernst, Karl-Heinz; Baumann, Susanne; Lutz, Christopher P; Seibel, Johannes; Zoppi, Laura; Heinrich, Andreas J

    2015-08-12

    Understanding the principles of molecular recognition is a difficult task and calls for investigation of appropriate model systems. Using the manipulation capabilities of scanning tunneling microscopy (STM) we analyzed the chiral recognition in self-assembled dimers of helical hydrocarbons at the single molecule level. After manual separation of the two molecules of a dimer with a molecule-terminated STM tip on a Cu(111) surface, their handedness was subsequently determined with a metal atom-terminated tip. We find that these molecules strongly prefer to form heterochiral pairs. Our study shows that single molecule manipulation is a valuable tool to understand intermolecular recognition at surfaces. PMID:26121366

  2. Separation of chiral drugs with β-CD phosphate by capillary electrophoresis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    β -Cyclodextrin phosphate (β -CD-phosphate) was used as a selector for separating chiral drugs by capillary electrophoresis (CE). A solution comprising of 120 mmol/L Britton-Robinson buffer (BRB) containing 10 mmol/L β -CD phosphate with the pH adjusted to 7.0 was used as the background electrolyte (BGE), and a small amount of analyte was injected (600v/1s). Triethylamine, diethylamine, triethanolamine, diethanolamine, Tris added as modifier were compared. Isoprenaline, methoxamine, oxprenolol, practolol were successfully resolved.

  3. Novel chiral stationary phases based on peptoid combining a quinine/quinidine moiety through a C9-position carbamate group.

    Science.gov (United States)

    Wu, Haibo; Wang, Dongqiang; Song, Guangjun; Ke, Yanxiong; Liang, Xinmiao

    2014-04-01

    By connecting a quinine or quinidine moiety to the peptoid chain through the C9-position carbamate group, we synthesized two new chiral selectors. After immobilizing them onto 3-mercaptopropyl-modified silica gel, two novel chiral stationary phases were prepared. With neutral, acid, and basic chiral compounds as analytes, we evaluated these two stationary phases and compared their chromatographic performance with chiral columns based on quinine tert-butyl carbamate and the previous peptoid. From the resolution of neutral and basic analytes under normal-phase mode, it was found that the new stationary phases exhibited much better enantioselectivity than the quinine tert-butyl carbamate column; the peptoid moiety played an important role in enantiorecognition, which controlled the elution orders of enantiomers; the assisting role of the cinchona alkaloid moieties was observed in some separations. Under acid polar organic phase mode, it was proved that cinchona alkaloid moieties introduced excellent enantiorecognitions for chiral acid compounds; in some separations, the peptoid moiety affected enantioseparations as well. Overall, chiral moieties with specific enantioselectivity were demonstrated to improve the performance of peptoid chiral stationary phase efficiently.

  4. Chiral separation of cathinone and amphetamine derivatives by HPLC/UV using sulfated ß-cyclodextrin as chiral mobile phase additive.

    Science.gov (United States)

    Taschwer, Magdalena; Seidl, Yvonne; Mohr, Stefan; Schmid, Martin G

    2014-08-01

    In the last years the identification of new legal and illegal highs has become a huge challenge for the police and prosecution authorities. In an analytical context, only a few analytical methods are available to identify these new substances. Moreover, many of these recreational drugs are chiral and it is supposed that the enantiomers differ in their pharmacological potency. Since nonenantioselective synthesis is easier and cheaper, they are mainly sold as racemic mixtures. The goal of this research work was to develop an inexpensive method for the chiral separation of cathinones and amphetamines. This should help to discover if the substances are sold as racemic mixtures and give further information about their quality as well as their origin. Chiral separation of a set of 6 amphetamine and 25 cathinone derivatives, mainly purchased from various Internet shops, is presented. A LiChrospher 100 RP-18e, 250 x 4 mm, 5 µm served as the stationary phase. The chiral mobile phase consisted of methanol, water, and sulfated ß-cyclodextrin. Measurements were performed under isocratic conditions in reversed phase mode using UV detection. Four model compounds of the two substance classes were used to optimize the mobile phase. Under final conditions (methanol:water 2.5:97.5 + 2% sulfated ß-cyclodextrin) enantiomers of amphetamine and five derivatives were baseline separated within 23 min. In all, 17 cathinones were completely or partially chirally separated. However, as only 3 of 25 cathinones were baseline resolved, the application of this method is limited for cathinone analogs. Additionally, the results were compared with an RP-8e column.

  5. Separation of Ofloxacin and Its Six Related Substances Enantiomers by Chiral Ligand-Exchange Chromatography.

    Science.gov (United States)

    Liang, Xinlei; Zhao, Longshan; Deng, Miaoduo; Liu, Lijie; Ma, Yongfu; Guo, Xingjie

    2015-11-01

    A chiral ligand-exchange high-performance liquid chromatography method was developed for the enantioseparation of ofloxacin and its six related substances termed impurities A, B, C, D, E, and F. The separation was performed on a conventional C18 column. Different organic modifiers, copper salts, amino acids, the ratio of Cu(2+) to amino acid, pH of aqueous phase, and column temperature were optimized. The optimal mobile phase conditions were methanol-water systems consisting of 5 mmol/L copper sulfate and 10 mmol/L L-isoleucine (L-Ile). Under such conditions, good enantioseparation of ofloxacin and impurities A, C, E, and F could be observed with resolutions (RS ) of 3.54, 1.97, 3.21, 3.50, and 2.12, respectively. On the relationship between the thermodynamic parameters and structures of analytes, the mechanism of chiral recognition was investigated. It was concluded that ofloxacin and impurities A, C, E, and F were all enthalpically driven enantioseparation and that low column temperature was beneficial to enantioseparation. Furthermore, the structure-separation relationship of these analytes is also discussed.

  6. Quality by design in the chiral separation strategy for the determination of enantiomeric impurities: development of a capillary electrophoresis method based on dual cyclodextrin systems for the analysis of levosulpiride.

    Science.gov (United States)

    Orlandini, S; Pasquini, B; Del Bubba, M; Pinzauti, S; Furlanetto, S

    2015-02-01

    Quality by design (QbD) concepts, in accordance with International Conference on Harmonisation Pharmaceutical Development guideline Q8(R2), represent an innovative strategy for the development of analytical methods. In this paper QbD principles have been comprehensively applied in the set-up of a capillary electrophoresis method aimed to quantify enantiomeric impurities. The test compound was the chiral drug substance levosulpiride (S-SUL) and the developed method was intended to be used for routine analysis of the pharmaceutical product. The target of analytical QbD approach is to establish a design space (DS) of critical process parameters (CPPs) where the critical quality attributes (CQAs) of the method have been assured to fulfil the desired requirements with a selected probability. QbD can improve the understanding of the enantioseparation process, including both the electrophoretic behavior of enantiomers and their separation, therefore enabling its control. The CQAs were represented by enantioresolution and analysis time. The scouting phase made it possible to select a separation system made by sulfated-β-cyclodextrin and a neutral cyclodextrin, operating in reverse polarity mode. The type of neutral cyclodextrin was included among other CPPs, both instrumental and related to background electrolyte composition, which were evaluated in a screening phase by an asymmetric screening matrix. Response surface methodology was carried out by a Doehlert design and allowed the contour plots to be drawn, highlighting significant interactions between some of the CPPs. DS was defined by applying Monte-Carlo simulations, and corresponded to the following intervals: sulfated-β-cyclodextrin concentration, 9-12 mM; methyl-β-cyclodextrin concentration, 29-38 mM; Britton-Robinson buffer pH, 3.24-3.50; voltage, 12-14 kV. Robustness of the method was examined by a Plackett-Burman matrix and the obtained results, together with system repeatability data, led to define a method

  7. Separation of mandelic acid and its derivatives with new immobilized cellulose chiral stationary phase

    Institute of Scientific and Technical Information of China (English)

    Jie ZHOU; Qian LIU; Guang-jun FU; Zhen-zhong ZHANG

    2013-01-01

    A new liquid chromatographic method has been developed for the chiral separation of the enantiomers of mandelic acid and their derivatives 2-chloromandelic acid,4-hydroxymandelic acid,4-methoxymandelic acid,and 3,4,5-trismethoxymandelic acid.The enantiomers were separated by a CHIRALPAK(R) IC (250 mm×4.6 mm,5 μm).Mandelic acid,4-methoxymandelic acid,and 3,4,5-trismethoxymandelic acid were baseline resolved (resolution factor (Rs)=2.21,Rs=2.14,and Rs=3.70,respectively).In contrast,the enantioselectivities between CHIRALPAK(R) IC and 2-chloromandelic acid and 4-hydroxymandelic acid investigated were low.By comparing the chromatographs of mandelic acid enantiomers and mandelic acid spiked with (R)-mandelic acid,it was determined that the first effluent was (R)-mandelic acid.

  8. Study of the correlation of charge separation of the chiral magnetic effect in Relativistic Heavy-ion Collisions

    CERN Document Server

    Feng, Sheng-Qin; Sun, Fei; Zhong, Yang; Yin, Zhong-Bao

    2016-01-01

    It was pointed out that the Chiral Magnetic Effect is a process of charge separation with respect to the reaction plane. There is one kind of phenomenon of gauge field configurations with nonzero topological charge, which can be a sphaleron in the QCD vacuum. At high temperatures, one expects that the sphaleron process is a dominant process. One finds that left-handed quarks will become right-handed quarks, and right-handed quarks will remain right-handed in a region with negative topological charge. The strong magnetic field produced in relativistic heavy-ion collisions interacts with the magnetic moment of the quarks and locates the spins of quarks with positive (negative) electric charge to be parallel (anti-parallel) to the field direction. The Chiral Separation Effect is a similar effect in which the occurrence of a vector charge, e.g. electric charge, causes a separation of chiralities. We calculate the chiral separation effects during RHIC and LHC energy regions by studying the detailed chiral charge s...

  9. Enantiomeric Separation of Epinephrine and Salbutamol by Micellar Electrokinetic Chromatography Using β-Cyclodextrin as Chiral Additive

    Institute of Scientific and Technical Information of China (English)

    ZHENG,Yan-Peng(郑妍鹏); MO,Jin-Yuan(莫金垣)

    2004-01-01

    Enantiomeric separations of epinephrine and salbutamol, by means of micellar electrokinetic chromatography (MEKC) employing β-cyclodextrin as chiral additive in ammonium chloride-ammonia solution were investigated.In this system, the analytes migrated with the micellar phase towards the anode and were detected by electrochemistry using gold microelectrode at +0.65 V vs. SCE. The success of the chiral separations is strongly dependent on the concentration of β-CD and SDS, and the optimal concentration is 8 mmol·L-1 and 15 mmol·L-1 respectively.The effects of detection potential, pH value of electrolyte and applied voltage were discussed also. Using the proposed method, baseline separation of the enantiomers could be accomplished in 6 min. Further, an attempt was made to elucidate the plausible mechanism of the chiral recognition.

  10. A novel approach for LC-MS/MS-based chiral metabolomics fingerprinting and chiral metabolomics extraction using a pair of enantiomers of chiral derivatization reagents.

    Science.gov (United States)

    Takayama, Takahiro; Mochizuki, Toshiki; Todoroki, Kenichiro; Min, Jun Zhe; Mizuno, Hajime; Inoue, Koichi; Akatsu, Hiroyasu; Noge, Ichiro; Toyo'oka, Toshimasa

    2015-10-22

    Chiral metabolites are found in a wide variety of living organisms and some of them are understood to be physiologically active compounds and biomarkers. However, the overall analysis of chiral metabolomics is quite difficult due to the high number of metabolites, the significant diversity in their physicochemical properties, and concentration range from metabolite-to-metabolite. To solve this difficulty, we developed a novel approach for chiral metabolomics fingerprinting and chiral metabolomics extraction, which is based on the labeling of a pair of enantiomers of chiral derivatization reagents (i.e., DMT-(S,R)-Pro-OSu and DMT-3(S,R)-Apy) and precursor ion scan chromatography of the derivatives. The multivariate statistics is also required for this strategy. The proposed procedures were evaluated by the detection of a diagnostic marker (i.e., d-lactic acid) using the saliva of diabetic patients. This method was used for the determination of biomarker candidates of chiral amines and carboxyls in Alzheimer's disease (AD) brain homogenates. As the results, l-phenylalanine (L-Phe) and l-lactic acid (L-LA) were identified as the decreased and increased biomarker candidates in the AD brain, respectively. Therefore, the proposed approach seems to be helpful for the determination of non-target chiral metabolomics possessing amines and carboxyls. PMID:26526912

  11. Elastic properties of chiral, anti-chiral, and hierarchical honeycombs:A simple energy-based approach

    Institute of Scientific and Technical Information of China (English)

    Davood Mousanezhad; Babak Haghpanah; Ranajay Ghosh; Abdel Magid Hamouda; Hamid Nayeb-Hashemi; Ashkan Vaziri

    2016-01-01

    The effects of two geometric refinement strategies widespread in natural structures, chirality and self-similar hierarchy, on the in-plane elastic response of two-dimensional honeycombs were studied systematically. Simple closed-form expressions were derived for the elastic moduli of several chiral, anti-chiral, and hierarchical honeycombs with hexagon and square based networks. Finite element analysis was employed to validate the analytical estimates of the elastic moduli. The results were also compared with the numerical and experimental data available in the literature. We found that introducing a hier-archical refinement increases the Young’s modulus of hexagon based honeycombs while decreases their shear modulus. For square based honeycombs, hierarchy increases the shear modulus while decreasing their Young’s modulus. Introducing chirality was shown to always decrease the Young’s modulus and Poisson’s ratio of the structure. However, chirality remains the only route to auxeticity. In particular, we found that anti-tetra-chiral structures were capable of simultaneously exhibiting anisotropy, auxeticity, and remarkably low shear modulus as the magnitude of the chirality of the unit cell increases.

  12. 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.

  13. Chiral Antioxidant-based Gold Nanoclusters Reprogram DNA Epigenetic Patterns.

    Science.gov (United States)

    Ma, Yue; Fu, Hualin; Zhang, Chunlei; Cheng, Shangli; Gao, Jie; Wang, Zhen; Jin, Weilin; Conde, João; Cui, Daxiang

    2016-01-01

    Epigenetic modifications sit 'on top of' the genome and influence DNA transcription, which can force a significant impact on cellular behavior and phenotype and, consequently human development and disease. Conventional methods for evaluating epigenetic modifications have inherent limitations and, hence, new methods based on nanoscale devices are needed. Here, we found that antioxidant (glutathione) chiral gold nanoclusters induce a decrease of 5-hydroxymethylcytosine (5hmC), which is an important epigenetic marker that associates with gene transcription regulation. This epigenetic change was triggered partially through ROS activation and oxidation generated by the treatment with glutathione chiral gold nanoclusters, which may inhibit the activity of TET proteins catalyzing the conversion of 5-methylcytosine (5mC) to 5hmC. In addition, these chiral gold nanoclusters can downregulate TET1 and TET2 mRNA expression. Alteration of TET-5hmC signaling will then affect several downstream targets and be involved in many aspects of cell behavior. We demonstrate for the first time that antioxidant-based chiral gold nanomaterials have a direct effect on epigenetic process of TET-5hmC pathways and reveal critical DNA demethylation patterns. PMID:27633378

  14. Chiral Antioxidant-based Gold Nanoclusters Reprogram DNA Epigenetic Patterns

    Science.gov (United States)

    Ma, Yue; Fu, Hualin; Zhang, Chunlei; Cheng, Shangli; Gao, Jie; Wang, Zhen; Jin, Weilin; Conde, João; Cui, Daxiang

    2016-01-01

    Epigenetic modifications sit ‘on top of’ the genome and influence DNA transcription, which can force a significant impact on cellular behavior and phenotype and, consequently human development and disease. Conventional methods for evaluating epigenetic modifications have inherent limitations and, hence, new methods based on nanoscale devices are needed. Here, we found that antioxidant (glutathione) chiral gold nanoclusters induce a decrease of 5-hydroxymethylcytosine (5hmC), which is an important epigenetic marker that associates with gene transcription regulation. This epigenetic change was triggered partially through ROS activation and oxidation generated by the treatment with glutathione chiral gold nanoclusters, which may inhibit the activity of TET proteins catalyzing the conversion of 5-methylcytosine (5mC) to 5hmC. In addition, these chiral gold nanoclusters can downregulate TET1 and TET2 mRNA expression. Alteration of TET-5hmC signaling will then affect several downstream targets and be involved in many aspects of cell behavior. We demonstrate for the first time that antioxidant-based chiral gold nanomaterials have a direct effect on epigenetic process of TET-5hmC pathways and reveal critical DNA demethylation patterns. PMID:27633378

  15. Separação cromatográfica quiral de anestésicos a partir de soluções diluídas e concentradas em escala preparativa Chiral chromatographic separation of anesthetics from dilute and concentrated solutions under preparative scale

    Directory of Open Access Journals (Sweden)

    Ivanildo José da Silva Jr.

    2009-01-01

    Full Text Available In this work the separation of the chiral anesthetic compounds ketamine and bupivacaine was development using two chiral stationary phases (CSP. Ketamine enantiomers were well separate in the polysaccharide-based CSP (microcrystalline cellulose triacetate - MCTA while bupivacaine in the tartardiamide-based CSP (Kromasil CHI-TBB. In both cases, the effect of temperature was investigated under analytical conditions. An improvement in the separation performance with temperature was observed. Thermodynamic parameters were evaluated by the van't Hoff plot. We concluded that enthalpic effects controlled the retention in these chiral columns. The enantiomers of ketamine and bupivacaine were separated under overloaded conditions with a good performance.

  16. 奎宁-冠醚组合型手性固定相直接拆分氨基酸的机理%Separation mechanism of chiral stationary phase based on quinine and crown ether for the direct stereoselective separation of amino acids

    Institute of Scientific and Technical Information of China (English)

    吴海霞; 王东强; 赵见超; 柯燕雄; 梁鑫淼

    2016-01-01

    合成了一种新型奎宁-冠醚组合型手性固定相( QN-CR CSP)并用于氨基酸手性对映体的直接拆分,该固定相对12种氨基酸对映体有良好的手性拆分能力。基于氨基酸手性识别中离子交换和络合的协同作用,建立了一种新型的等温吸附模型。通过迎头特殊点洗脱法( FACP)测定色氨酸( Trp)在不同金属离子添加剂条件下的等温吸附线,验证了模型的合理性。流动相中的 Li+、Na+、K+等金属离子与氨基酸竞争固定相中的冠醚络合位点,随着金属离子与冠醚的络合作用力和络合吸附平衡常数增大,固定相对 Trp的手性拆分能力下降。该模型的建立对理解氨基酸在此类固定相中的手性保留行为以及固定相结构的进一步优化具有重要意义。%A novel chiral stationary phase combining quinine and crown ether( QN-CR CSP ) was developed to separate amino acid enantiomers. This CSP showed good enantioselectivity for some amino acids. Since the synergistic effect of ion exchange and complexation in chiral recognition of amino acids,a new adsorption isotherm was built. Using the method of frontal analysis by characteristic point( FACP),the adsorption isotherms of tryptophan( Trp)under different mobile phase conditions were determined and fitted the proposed adsorption isotherm model well. With the increase of the competition between metal cationic and amino to crown ether,the equilibrium constant of complexing adsorption was found increased. The chiral sepa-ration ability was decreased. The adsorption isotherm improved the understanding of the reten-tion behavior of amino acids on QN-CR CSP,which was also benefit to optimize the structure of the stationary phase.

  17. Chiral stationary phases based on chitosan bis(methylphenylcarbamate)-(isobutyrylamide) for high-performance liquid chromatography.

    Science.gov (United States)

    Tang, Sheng; Bin, Qin; Chen, Wei; Bai, Zheng-Wu; Huang, Shao-Hua

    2016-04-01

    A series of chitosan bis(methylphenylcarbamate)-(isobutyrylamide) derivatives were synthesized by carbamylating chitosan isobutyrylamide with different methylphenyl isocyanates. Then the prepared chitosan derivatives were coated onto 3-aminopropyl silica particles, resulting in a series of new chiral stationary phases (CSPs) for high-performance liquid chromatography. It was observed that the chiral recognition abilities of these coated-type CSPs depended very much on the substituents on the phenyl moieties of the chitosan derivatives, the eluent composition, as well as the structure of racemates. As a typical example, the eluent tolerance of the prepared CSP with the best enantioseparation ability was investigated in detail, and the results revealed that the CSP exhibited extraordinary solvent tolerance and could still work without significant loss in enantioseparation capability after being flushed with chloroform (100%), ethyl acetate (100%) and even THF/n-hexane (70/30, v/v), while the traditional coated-type CSPs based on the cellulose and amylose derivatives, such as cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) and amylose tris(3,5-dimethylphenylcarbamate) (ADMPC), might be dissolved or highly swollen in these eluents. Therefore, the application of the resultant CSPs could address the problem of the dissolution and high swelling of traditional coated-type CSPs in some unusual eluents, broadening the possibility of eluent choice. In addition, a comparison of the prepared CSPs with the well known CDMPC- and ADMPC- based CSPs concerning the chiral recognition ability was also made. Separation performances achieved on the as-prepared CSPs in different eluents were found to be even superior to CDMPC- and ADMPC-based CSPs for the tested chiral compounds. In summary, we could safely draw the conclusion that the CSPs derived from chitosan isobutyrylamide derivatives were capable of excellent chiral recognition ability, and meanwhile possessed satisfactory

  18. Enantioselective and diastereoselective separation of synthetic pyrethroid insecticides on a novel chiral stationary phase by high-performance liquid chromatography.

    Science.gov (United States)

    Tan, Xulin; Hou, Shicong; Wang, Min

    2007-07-01

    A novel chiral packing material for high-performance liquid chromatography (HPLC) was prepared by connecting (R)-1-phenyl-2-(4-methylphenyl) ethylamine (PTE) amide derivative of (S)-isoleucine to aminopropyl silica gel through 2-amino-3,5-dinitro-1-carboxamido-benzene unit. This chiral stationary phase was applied to the enantioselective and diastereoselective separation of five pyrethroid insecticides by HPLC under normal phase condition. To achieve satisfactory baseline separation an optimization of the variables of mobile phase composition was required. The two enantiomers of fenpropathrin and four stereoisomers of fenvalerate were baseline separated using hexane-1,2-dichloroethane-2-propanol as mobile phase. The results show that the enantioselectivity of CSP is better than Pirkle type 1-A column for these compounds. Only partial separations for the cypermethrin and cyfluthrin stereoisomers were observed. Seven peaks and eight peaks were observed for cypermethrin and cyfluthrin, respectively. The elution orders were assigned by using different stereoisomer-enriched products.

  19. Enantiomer separation of acidic chiral compounds on a quinine-silica/zirconia hybrid monolith by capillary electrochromatography.

    Science.gov (United States)

    Tran, Le Ngoc; Park, Jung Hag

    2015-05-29

    A weak anion-exchanger chiral selector, quinine-incorporated silica/zirconia hybrid monolithic (QUI-S/ZHM) capillary column was prepared by sol-gel technology. The performance of the QUI-S/ZHM column was investigated for enantioresolution of a set of acidic chiral drugs and dinitrobenzoyl (DNB)-amino acids by capillary electrochromatography in aqueous organic mobile phases composed of acetonitrile (ACN) and triethylammonium acetate (TEAA) buffer. Effects of several parameters including the ACN content, concentration and pH of the mobile phase on the chiral separation were examined. Baseline resolutions of all the compounds were obtained in the mobile phase consisting of 70:30 ACN/TEAA (10mM, pH 6) under applied voltage of -10kV at 25°C within 20min.

  20. Synthesis of ino Acid Derived β-Cyclodextrins Used in Chiral Separation by Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    戴荣继; 佟斌; 魏征; 顾峻岭; 邓玉林; 李明愉; 傅若农

    2004-01-01

    Six new kinds of ino acid derived β-cyclodextrins were synthesized to improve their water solubility and chiral separation properties. They are heptakis{2,6-di-O-[3-L-(1-isopropyl carboxyl methyl ino)-2-hydroxy propyl]}-β-cyclodextrin (i.e. L-Val-β-CD), heptakis{2,6-di-O-[3-L-(1-benzyl carboxyl methyl ino)-2-hydroxy propyl]}-β-cyclodextrin (i.e. L-Phe-β-CD), heptakis{2,6-di-O-[3-(D, L-1-benzyl carboxyl methyl ino)-2-hydroxy propyl]}-β-cyclodextrin (i.e. D,L-Phe-β-CD), heptakis{2,6-di-O-[3-(L-1-hydroxymethyl carboxyl methyl ino)-2-hydroxy propyl]}-β-cyclodextrin (i.e. L-Ser-β-CD), heptakis{2,6-di-O-[3-(L-1-carboxylmethyl carboxyl methyl ino)- 2-hydroxy propyl]}-β-cyclodextrin (i.e. L-Asp-β-CD), heptakis{2,6-di-O-[3-(L-2-carboxyl tetrethylene ino)-2-hydroxy propyl]}-β-cyclodextrin (i.e. L-Pro-β-CD). Their chemical structures were certified using FTIR and 1H NMR. Except for L-Phe-β-CD and D,L-Phe-β-CD, that are in soluble in water, the other ino acid derived β-CDs all have good water solubility. D,L-tyrosine and promethazine were baselinely separated by L-Val-β-CD in capillary electrophoresis.

  1. High performance liquid chromatographic separation of eight drugs collected in Chinese Pharmacopoeia 2010 on amylose ramification chiral stationary phase

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2012-10-01

    Full Text Available The enantiomers separation of eight pharmaceutical racemates collected in Chinese Pharmacopoeia 2010 (Ch.P2010, including nitrendipine, felodipine, omeprazole, praziquantel, sulpiride, clenbuterol hydrochloride, verapamil hydrochloride and chlorphenamine maleate, was performed on chiral stationary phase of amylose ramification by high performance liquid chromatography (HPLC on Chiralpak AD-H column and Chiralpak AS-H column with the mobile phase consisted of isopropanol and n-hexane. The detection wavelength and the flow rate were set at 254 nm and 0.7 mL/min, respectively. The effects of proportion of organic additives, alcohol displacer and temperature on the separation were investigated. The results indicated that eight chiral drugs were separated on chiral stationary phase of amylase ramification in normal phase chromatographic system. The chromatographic retention and resolution of enantiomers were adjusted by factors, including the changes of the concentration of alcohol displacer in mobile phase, organic alkaline modifier and column temperature. It was shown that the resolution was improved with reducing concentration of alcohol displacer. When the concentration of organic alkaline modifier was 0.2%, the resolution and the peak shape were fairly good. Most racemates mentioned above had the best resolution at column temperature of 25 °C. The best temperature should be kept unchanged in the process of separation so as to obtain stable separation results.

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  3. The CGC enantiomer separation of 2-arylcarboxylic acid esters by using β-cyclodextrin derivatives as chiral stationary phases.

    Science.gov (United States)

    Shi, Xueyan; Liu, Feipeng; Mao, Jianyou

    2016-03-17

    Chiral 2-arylcarboxylic acid esters are important intermediates in preparation of enantioenriched 2-arylpropionic acids type Non-steroidal anti-inflammatory drugs (NSAIDs). Enantiomer separation of 2-arylcarboxylic acid esters is crucial for evaluation of the asymmetric synthesis efficiency and the enantiomer excess of chiral 2-arylcarboxylic acid derivatives. The capillary gas chromatography (CGC) enantiomer separation of 17 pairs of 2-arylcarboxylic acid esters enantiomers was conducted by using seven different β-cyclodextrin derivatives (CDs) as chiral stationary phases. It was found that for the 7 pairs of 2-phenylpropionates enantiomers, CDs with both alkyl and acyl substituents especially 2,6-di-O-pentyl-3-O-butyryl-β-cyclodextrin exhibited better enantiomer separation abilities than the other CDs examined. For the 7 pairs of 2-(4-substituted phenyl)propionates enantiomers, 2,3,6-tri-O-methyl-β-cyclodextrin possessed better enantiomer separation abilities than the other CDs. Among the 3 pairs of 2-phenylbutyrates enantiomers examined, only methyl 2-phenylbutyrate enantiomers could be separated by three CDs among the 7 CDs tested, while enantiomers of ethyl 2-phenylbutyrate and isopropyl 2-phenylbutyrate couldn't be separated by any of the 7 CDs tested. Besides the structures of CDs, the structures of 2-arylcarboxylic acid esters including different ester moieties, substituents of phenyl, and different carboxylic acids moieties in 2-arylcarboxylic acid esters also affected the enantiomer separation results greatly. The CGC enantiomer separation results of 2-arylcarboxylic acid esters on different CDs are useful for solving the enantiomer separation problem of 2-arylcarboxylic acid esters. PMID:26920785

  4. Kinetic study on reactive extraction for chiral separation of phenylsuccinic acid enantiomers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The kinetics of the extraction of phenylsuccinic acid(PSA) enantiomers by hydroxypropyl-β-cyclodextrin(HP-β-CD) in a modified Lewis cell was studied,in which HP-β-CD dissolved in 0.1 mol L-1 NaH2PO4/H3PO4 buffer solution(pH = 2.5) was selected as the chiral extractant.PSA enantiomers were extracted from organic phase to aqueous phase in the extraction module.The theory of extraction accompanied by a chemical reaction has been used to obtain the intrinsic kinetics of this extraction module.The different parameters affecting the extraction rate such as agitation speed,interfacial area,initial concentration of PSA enantiomers in organic phase as well as HP-β-CD concentration in aqueous phase were separately studied.The experimental results demonstrate that the extraction reactions are fast.The reactions were found to be first order with respect to PSA and second order with respect to HP-β-CD with forward rate constants of 3.4 × 10-2 m6 mol-2 s-1 for R-PSA and 9.96 × 10?3 m6 mol-2 s-1 for S-PSA.These data will be useful in the design of extraction processes.

  5. Enantiomeric separation of volatile organics by gas chromatography for the in situ analysis of extraterrestrial materials: kinetics and thermodynamics investigation of various chiral stationary phases.

    Science.gov (United States)

    Freissinet, C; Buch, A; Szopa, C; Sternberg, R

    2013-09-01

    The performances of several commercial chiral capillary columns have been evaluated with the aim of determining the one most suitable for enantiomeric separation in a gas chromatograph onboard a space probe. We compared the GC-MS response of three capillary columns coated with different chiral stationary phases (CSP) using volatile chiral organic molecules which are potential markers of a prebiotic organic chemistry. The three different chiral capillary columns are Chirasil-Val, with an amino acid derivative CSP, ChiralDex-β-PM, with a CSP composed of dissolved permethylated β-cyclodextrins in polysiloxane, and Chirasil-Dex, with a CSP made of modified cyclodextrins chemically bonded to the polysiloxane backbone. Both kinetics and thermodynamics studies have been carried out to evaluate the chiral recognition potential in these different types of columns. The thermodynamic parameters also allow a better understanding of the driving forces affecting the retention and separation of the enantiomers. The Chirasil-Dex-CSP displays the best characteristics for an optimal resolution of the chiral compounds, without preliminary derivatization. This CSP had been chosen to be the only chiral column in the Sample Analysis at Mars (SAM) experiment onboard the current Mars Science Laboratory (MSL) mission, and is also part of the Mars Organic Molecules Analyzer (MOMA) gas chromatograph onboard the next Martian mission ExoMars. The use of this column could also be extended to all space missions aimed at studying chirality in space.

  6. The vorticity induced chiral separation effect from the compactified D4-branes with smeared D0-brane charge

    CERN Document Server

    Wu, Chao; Huang, Mei

    2016-01-01

    By using the boundary derivative expansion formalism of fluid/gravity correspondence, we study the chiral vortical separation effect in a strongly coupled nonconformal relativistic fluid in the background of D0-D4 Sakai-Sugimoto model. The relativistic fluid of this model is nonconformal with a conserved axial vector current, and the presence of the chiral vortical separation effect is induced by the addition of a Chern-Simons term in the bulk action. Except the non-dissipative anomalous viscous coefficient and the sound speed, all other thermal and hydrodynamical quantities of first order depend on the temperature and the axial chemical potential. Stability analysis shows that this anomalous relativistic fluid is stable and the doping of smeared D0-brane will slow down the sound speed.

  7. New generation chiral metamaterials with small and flat chirality over a certain frequency band based on circular split ring resonators for microwave filter applications

    Science.gov (United States)

    Dincer, Furkan; Akgol, Oguzhan; Karaaslan, Muharrem; Unal, Emin; Demirel, Ekrem; Sabah, Cumali

    2016-02-01

    There are many studies in literature on chiral metamaterials (MTMs) to obtain large chiralities with dynamic optical activities. With this regard, this new generation planar chiral MTM study focuses on a small, non-dispersive (constant/flat) chirality admittance over an indicated frequency band which has not been investigated so far in literature. This new generation planar chiral MTM provides a small and a constant/fixed chirality which is mostly ignored by the scientists. This study numerically and experimentally investigates and examines these new generation MTMs based on circular split ring resonators (SRRs) with an increased capacitance in details. Obtained results show that the suggested structure can provide a small and constant/flat chirality admittance over a certain frequency band and hence it can be used to design myriad novel electromagnetic (EM) devices such as transmission and antireflection filters, polarization rotators for any desired frequency regions.

  8. Separation mechanism of chiral impurities, ephedrine and pseudoephedrine, found in amphetamine-type substances using achiral modifiers in the gas phase.

    Science.gov (United States)

    Holness, Howard K; Jamal, Adeel; Mebel, Alexander; Almirall, José R

    2012-11-01

    A new mechanism is proposed that describes the gas-phase separation of chiral molecules found in amphetamine-type substances (ATS) by the use of high-resolution ion mobility spectrometry (IMS). Straight-chain achiral alcohols of increasing carbon chain length, from methanol to n-octanol, are used as drift gas modifiers in IMS to highlight the mechanism proposed for gas-phase separations of these chiral molecules. The results suggest the possibility of using these achiral modifiers to separate the chiral molecules (R,S) and (S,R)-ephedrine and (S,S) and (R,R)-pseudoephedrine which contain an internal hydroxyl group at the first chiral center and an amino group at the other chiral center. Ionization was achieved with an electrospray source, the ions were introduced into an IMS with a resolving power of 80, and the resulting ion clusters were characterized with a coupled quadrupole mass spectrometer detector. A complementary computational study conducted at the density functional B3LYP/6-31g level of theory for the electronic structure of the analyte-modifier clusters was also performed, and showed either "bridged" or "independent" binding. The combined experimental and simulation data support the proposed mechanism for gas-phase chiral separations using achiral modifiers in the gas phase, thus enhancing the potential to conduct fast chiral separations with relative ease and efficiency.

  9. Resolution and isolation of enantiomers of (±)-isoxsuprine using thin silica gel layers impregnated with L-glutamic acid, comparison of separation of its diastereomers prepared with chiral derivatizing reagents having L-amino acids as chiral auxiliaries.

    Science.gov (United States)

    Bhushan, Ravi; Nagar, Hariom

    2015-03-01

    Thin silica gel layers impregnated with optically pure l-glutamic acid were used for direct resolution of enantiomers of (±)-isoxsuprine in their native form. Three chiral derivatizing reagents, based on DFDNB moiety, were synthesized having l-alanine, l-valine and S-benzyl-l-cysteine as chiral auxiliaries. These were used to prepare diastereomers under microwave irradiation and conventional heating. The diastereomers were separated by reversed-phase high-performance liquid chromatography on a C18 column with detection at 340 nm using gradient elution with mobile phase containing aqueous trifluoroacetic acid and acetonitrile in different compositions and by thin-layer chromatography (TLC) on reversed phase (RP) C18 plates. Diastereomers prepared with enantiomerically pure (+)-isoxsuprine were used as standards for the determination of the elution order of diastereomers of (±)-isoxsuprine. The elution order in the experimental study of RP-TLC and RP-HPLC supported the developed optimized structures of diastereomers based on density functional theory. The limit of detection was 0.1-0.09 µg/mL in TLC while it was in the range of 22-23 pg/mL in HPLC and 11-13 ng/mL in RP-TLC for each enantiomer. The conditions of derivatization and chromatographic separation were optimized. The method was validated for accuracy, precision, limit of detection and limit of quantification.

  10. The synthesis and characterization of novel brush-type chiral stationary phase based on terpenoid selector for resolution of chiral drugs

    Directory of Open Access Journals (Sweden)

    Wang Dao-Cai

    2016-01-01

    Full Text Available In the light of the chiral resolution mechanism and structures of brush-type CSP, a new chiral selector 4′-carboxyl-1′-ursolic methyl ester-3β-yl-benzoate has been prepared. Then the terpenoid chiral selector was covalently linked to 3-aminopropyl silica gel. Its structure identification data are provided by 1H NMR, MS and elementary analysis. The enantiodiscriminating capability of the brush-type CSP was evaluated by static adsorption experiment with methyl mandelate, aniline derivative of mandelic acid, benzoin and ibuprofen. Experimental results demonstrated that the chiral selector has selectivity, and the enantiomers of methyl mandelate and ibuprofen could be separated on the CSP, which indicated that the novel brush-type CSP possess a bright prospects for chiral separation potentially.

  11. Advances in chiral separations of small peptides by capillary electrophoresis and chromatography.

    Science.gov (United States)

    Ali, Imran; Al-Othman, Zeid A; Al-Warthan, Abdulrahman; Asnin, Leonid; Chudinov, Alexander

    2014-09-01

    Many chemical and biological processes are controlled by the stereochemistry of small polypeptides (di-, tri-, tetra-, penta-, hexapeptides, etc). The biological importance of peptide stereoisomers is of great value. Therefore, the chiral resolution of peptides is an important issue in biological and medicinal sciences and drug industries. The chiral resolutions of peptide racemates have been discussed with the use of capillary electrophoresis and chromatographic techniques. The various chiral selectors used were polysaccharides, cyclodextrins, Pirkle types, macrocyclic antibiotics, crown ethers, imprinted polymers, etc. The stereochemistry of dipeptides is also discussed. Besides, efforts are made to explain the chiral recognition mechanisms, which will be helpful in understanding existing and developing new stereoselective analyses. Future perspectives of enantiomeric resolution are also predicted. Finally, the review concludes with the demand of enantiomeric resolution of all naturally occurring and synthetic peptides. PMID:25044566

  12. Enantioselective extraction of mandelic acid enantiomers based on chiral ligand exchange

    Institute of Scientific and Technical Information of China (English)

    TANG Ke-wen; HUANG Ke-long

    2005-01-01

    Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-dodecyl-L-proline(A). The influences of the solvent sort, the pH value, the concentrations of Cu2+ and chiral ligand on the partition coefficient(K) and separation factor(α) were discussed. The experimental results show that the A formed has more stable ternary complex with D-mandelic acid enantiomer than with L-mandelic acid enantiomer. There is an important influence of the pH value on K and α. When the pH values are less than 3.5, the formation of binary complexes is thermodynamically unfavourable. K and α become maximum when pH values are above 3.5 and the molar ratio of the chiral ligand to Cu2+ is 2:1.

  13. Enantiomerically Pure [2.2]Paracyclophane-4-thiol: A Planar Chiral Sulfur-Based Building Block Readily Available by Resolution with an Amino Acid Chiral Auxiliary.

    Science.gov (United States)

    Vincent, Adrien; Deschamps, Damien; Martzel, Thomas; Lohier, Jean-François; Richards, Christopher J; Gaumont, Annie-Claude; Perrio, Stéphane

    2016-05-01

    Acyl chloride of N-phthaloyl-(S)-isoleucine is an efficient chiral auxiliary for the resolution of (±)-[2.2]paracyclophane-4-thiol. A preparative protocol, based on the conversion into diastereoisomeric thiolesters and separation by two fractional crystallizations and column chromatography, was developed. Deprotection with LiAlH4 allowed isolation of the individual thiol enantiomers in good yield (∼40%) and high enantiomeric purity (ee >93%). The absolute configurations were determined by comparison of the optical rotation value of the products with literature data and were confirmed by X-ray crystallography. PMID:27081870

  14. Reversed-phase high-performance liquid chromatographic separation of diastereomers of (R,S)-mexiletine prepared by microwave irradiation with four new chiral derivatizing reagents based on trichloro-s-triazine having amino acids as chiral auxiliaries and 10 others having amino acid amides.

    Science.gov (United States)

    Bhushan, Ravi; Dixit, Shuchi

    2010-12-01

    A new series of chiral derivatizing reagents (CDRs) consisting of four dichloro-s-triazine reagents was synthesized by nucleophilic substitution of one chlorine atom in trichloro-s-triazine with amino acids, namely L-Leu, D-Phg, L-Val and L-Ala as chiral auxiliaries. Two other sets of CDRs consisting of four dichloro-s-triazine (DCT) and six monochloro-s-triazine (MCT) reagents were also prepared by nucleophilic substitution of chlorine atom(s) with different amino acid amides as chiral auxiliaries in trichloro-s-triazine and its 6-methoxy derivative, respectively. These 14 CDRs were used for the synthesis of diastereomers of (R,S)-mexiletine under microwave irradiation (i.e. 60s and 90 s at 85% power (of 800 W) using DCT and MCT reagents, respectively), which were resolved by reversed-phase high-performance liquid chromatography using C18 column and gradient eluting mixtures of methanol with aqueous trifluoroacetic acid (TFA) with UV detection at 230 nm. The resolution (R(s)), difference between retention times of resolved diastereomers (Δt) and retention factors (k) obtained for the three sets of diastereomers were compared among themselves and among the three groups. Explanations have been offered for longer retention times and better resolution of diastereomers prepared with DCT reagents in comparison of their MCT counterparts and, for the influence of hydrophobicity of the side chain R of the amino acid in the CDRs on retention times and resolution. The newly synthesized CDRs were observed to be superior as compared to their amide counterparts in terms of providing better resolution and cost effectiveness. The method was validated for limit of detection, linearity, accuracy and precision. PMID:21035811

  15. Design, chirality, and flexibility in nanoporous molecule-based materials.

    Science.gov (United States)

    Bradshaw, D; Claridge, J B; Cussen, E J; Prior, T J; Rosseinsky, M J

    2005-04-01

    Scientific and technological interest in porous materials with molecule-sized channels and cavities has led to an intense search for controlled chemical routes to systems with specific properties. This Account details our work on directing the assembly of open-framework structures based on molecules and investigating how the response of nanoporous examples of such materials to guests differs from classical rigid porous systems. The stabilization of chiral nanoporosity by a hierarchy of interactions that both direct and maintain a helical open-framework structure exemplifies the approach. PMID:15835874

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

    Science.gov (United States)

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-21

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

  17. Proline Based Chiral Ionic Liquids for Enantioselective Michael Reaction

    Directory of Open Access Journals (Sweden)

    Kaoru Nobuoka

    2014-01-01

    Full Text Available Chiral ionic liquids, starting from (S-proline, have been prepared and evaluated the ability of a chiral catalyst. In Michael reaction of trans-β-nitrostyrene and cyclohexanone, all the reactions were carried out under homogeneous conditions without any solvent except for excess cyclohexanone. The chiral ionic liquid catalyst with the positive charge delocalized bulky pyrrolidinium cation shows excellent yields (up to 92%, diastereoselectivities (syn/anti = 96/4, and enantioselectivities (up to 95% ee and could be reused at least three times without any loss of its catalytic activity. Such results demonstrated a promising new approach for green and economic chiral synthesis by using the chiral ionic liquids as a chiral catalyst and a chiral medium.

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

    Directory of Open Access Journals (Sweden)

    Bohua Sun

    2010-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  20. Chiral Separation and Identification of D,L-Histidine Based on Nanochannels Membrane Coupling with Surface Enhanced Raman Scattering Spectroscopy%基于纳米通道表面增强拉曼散射光谱分离检测组氨酸对映体的研究

    Institute of Scientific and Technical Information of China (English)

    钟桐生; 尹志芳; 柳悦; 黄杉生

    2015-01-01

    Gold nanochannels were prepared using Al2 O3 nanotubules membrane as the carrier and modified with chitosan by a classical N-(3-dimethylaminopropyl)-N-ethyl carbodiimide ( EDC)/N-hydroxysuccinimide ( NHS ) coupling reaction. The nanochannels were characterized by field emission scanning electron microscopy ( FESEM) , cyclic voltammetry and AC impedance method. The Au nanochannels modified with chitosan showed a chiral environment and can be used to separate histidine enantiomer. The effects of pore size and solution pH on the separation efficiency of histidine were investigated. To increase the detection sensitivity of D-, L-histidine, Ag nanoparticles were used to enhance the surface enhanced Raman scattering ( SERS) activity. The results showed that the chitosan-modified gold nanochannels can be used to separate chiral histidine based on this unique selective nanochannel membrane. L-Histidine and D-histidine were respectively detected by SERS at wavelengths of 1000 and 1590 cm-1 . The results showed that L-histidine and D-histidine were separated well in the mixture containing 200 μL of histidine, 100 μL of colloidal Ag and 100 μL of 80 mmol/L NaCl ( pH=7 . 59 ) with a separation efficiency of 4 . 91 .%以Al2 O3纳米通道膜为基体制备金纳米通道,以场发射扫描电镜、循环伏安、交流阻抗等方法对金纳米通道进行表征。采用EDC-NHS的交联反应,将壳聚糖自组装至金纳米通道孔壁上,形成表面具有手性位点选择性的功能化纳米通道膜,利用纳米通道优异的分离能力手性分离D-,L-组氨酸。考察了纳米通道孔径和溶液的pH值对分离效果的影响。采用银溶胶作为表面增强拉曼( SERS)测试的基底,增强对D-,L-组氨酸的SERS效应,提高检测该物质的选择性和灵敏度。分别在1000和1590 cm-1处测定L-组氨酸和D-组氨酸。在含200μL组氨酸、100μL银溶胶和100μL 80 mmol/L NaCl溶液(pH=7.59)中,D-组氨酸和L-组氨酸可得

  1. Graphene oxide based chiral diamine rhodium catalyst for asymmetric transfer hydrogenation of aromatic ketones

    Directory of Open Access Journals (Sweden)

    LIU Ketang

    2013-02-01

    Full Text Available Functional graphite oxide materials were synthesized through the Hummers chemical oxidation of graphite.Heterogeneous catalyst was prepared via direct grafting diamine-based chiral ligand to graphite oxide followed by the complexation with organorhodium complex.Such a chiral rhodium catalyst exhibited high catalytic activity and enantioselectivity in asymmetric transfer hydrogenation of aromatic ketones in aqueous medium under mild condition.

  2. Novel carbohydrate-based chiral ammonium ionic liquids derived from isomannide

    DEFF Research Database (Denmark)

    Kumar, Vineet; Pei, Cao; Olsen, Carl E.;

    2008-01-01

    This report describes the synthesis and characterization of novel carbohydrate-based chiral ammonium ionic liquids using isomannide as a biorenewable substrate. The diastereomeric interactions of these chiral ammonium ionic liquids with racemic Mosher's acid salt have been studied using NMR, which...

  3. Non-ionic surfactant modified ligand exchange chromatography using copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive for enantioselective amino acids separation.

    Science.gov (United States)

    Dimitrova, Pepa; Bart, Hans-Jörg

    2010-03-17

    The influence of non-ionic surfactants on the selectivity and retention in the ligand exchange chromatography for the enantioselective separation of racemic mixtures of the amino acids dl-methionine, dl-leucine, dl-valine and dl-tyrosine applying chiral mobile phases was investigated, whereas five different surfactants were tested as modifiers. The experiments were carried out using a commercially available non-chiral RP-C8 column and the copper (II) complex of N,N-dimethyl-l-phenylalanine as the chiral additive. Varying the surfactant concentrations the retention factors and the selectivity could be controlled and in general no negative influence on the separation (due to surfactant adsorption on the non-chiral stationary phase) occurred. Changing the temperature the van't Hoff plots were obtained and the thermodynamic parameters calculated. Temperature had influence on the selectivity for each surfactant and lowered the retention times as expected.

  4. Non-ionic surfactant modified ligand exchange chromatography using copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive for enantioselective amino acids separation

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrova, Pepa [TU Kaiserslautern, Institut fuer Thermische Verfahrenstechnik, P.O. Box 3049, Gottlieb-Daimler-Str. 44, 67653 Kaiserslautern (Germany); Bart, Hans-Joerg, E-mail: bart@mv.uni-kl.de [TU Kaiserslautern, Institut fuer Thermische Verfahrenstechnik, P.O. Box 3049, Gottlieb-Daimler-Str. 44, 67653 Kaiserslautern (Germany)

    2010-03-17

    The influence of non-ionic surfactants on the selectivity and retention in the ligand exchange chromatography for the enantioselective separation of racemic mixtures of the amino acids DL-methionine, DL-leucine, DL-valine and DL-tyrosine applying chiral mobile phases was investigated, whereas five different surfactants were tested as modifiers. The experiments were carried out using a commercially available non-chiral RP-C8 column and the copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive. Varying the surfactant concentrations the retention factors and the selectivity could be controlled and in general no negative influence on the separation (due to surfactant adsorption on the non-chiral stationary phase) occurred. Changing the temperature the van't Hoff plots were obtained and the thermodynamic parameters calculated. Temperature had influence on the selectivity for each surfactant and lowered the retention times as expected.

  5. Enantiomeric separation of tapentadol by capillary electrophoresis--study of chiral selectivity manipulation by various types of cyclodextrins.

    Science.gov (United States)

    Znaleziona, Joanna; Fejős, Ida; Ševčík, Juraj; Douša, Michal; Béni, Szabolcs; Maier, Vítězslav

    2015-02-01

    The chiral recognition of the centrally acting analgesic agent tapentadol and its isomers with various cyclodextrins (CDs) was studied by capillary electrophoresis, focusing on the migration order of four stereoisomers. In the case of non-charged hydroxypropylated CDs (2-hydroxypropyl-β-CD, 2-hydroxypropyl-γ-CD) the beta derivative was able to discriminate the S,R- and R,S-isomers in acidic background electrolyte, whereas the gamma allowed the separation of S,S- and R,R-tapentadol, respectively. Dual CD system containing both hosts was used to separate all of four isomers. Negatively charged sulfated-α-CD at 1.0% (w/v) concentration in 100mM sodium borate buffer (pH 9.5) was capable of separating the isomers with favorable enantiomer migration order and the optimized method was able to determine 0.15% of chiral impurities of tapentadol in the presence of the last migrating clinically important R,R-isomer. PMID:25527976

  6. Enantiomeric separation of tapentadol by capillary electrophoresis--study of chiral selectivity manipulation by various types of cyclodextrins.

    Science.gov (United States)

    Znaleziona, Joanna; Fejős, Ida; Ševčík, Juraj; Douša, Michal; Béni, Szabolcs; Maier, Vítězslav

    2015-02-01

    The chiral recognition of the centrally acting analgesic agent tapentadol and its isomers with various cyclodextrins (CDs) was studied by capillary electrophoresis, focusing on the migration order of four stereoisomers. In the case of non-charged hydroxypropylated CDs (2-hydroxypropyl-β-CD, 2-hydroxypropyl-γ-CD) the beta derivative was able to discriminate the S,R- and R,S-isomers in acidic background electrolyte, whereas the gamma allowed the separation of S,S- and R,R-tapentadol, respectively. Dual CD system containing both hosts was used to separate all of four isomers. Negatively charged sulfated-α-CD at 1.0% (w/v) concentration in 100mM sodium borate buffer (pH 9.5) was capable of separating the isomers with favorable enantiomer migration order and the optimized method was able to determine 0.15% of chiral impurities of tapentadol in the presence of the last migrating clinically important R,R-isomer.

  7. Impact of the nature and composition of the mobile phase on the mass transfer mechanism in chiral reversed phase liquid chromatography. Application to the minimization of the solvent cost in chiral separations.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2014-01-31

    The mechanism of mass transfer was studied on a cellulose-based chiral stationary phase (CSP, Lux Cellulose-1) using aqueous mixtures of acetonitrile (50/50-90/10, v/v) or methanol (90/10 and 100/0, v/v) as the mobile phase. An experimental protocol validated in RPLC and HILIC chromatography and recently extended to chiral RPLC was applied. The five mass-transfer contributions (longitudinal diffusion, short-range and long-range eddy dispersion, solid-liquid mass transfer resistances due to finite intra-particle diffusivity and slow adsorption-desorption) to the reduced height equivalent to a theoretical plate (HETP) were measured. The experimental results show that the adsorption rate constants kads of trans-stilbene enantiomers onto the CSP are three times larger with acetonitrile than with methanol as the organic modifier. This is correlated to the decrease of enantioselectivity from 1.4 (in methanol) to only 1.1 (in acetonitrile). The amount of solvent needed to achieve a separation factor of exactly 2.0 was determined. This showed that analysis cost could be reduced seven times by selecting pure methanol as the eluent for a 5cm long column rather than an acetonitrile-water mixture for a longer (20-45cm) column.

  8. One-step preparation and application of mussel-inspired poly(norepinephrine)-coated polydimethylsiloxane microchip for separation of chiral compounds.

    Science.gov (United States)

    Chen, Juan; Liang, Ru-Ping; Wu, Lu-Lu; Qiu, Jian-Ding

    2016-07-01

    In this paper, using the self-polymerization of norepinephrine (NE) and its favorable film-forming property, a simple and green preparation approach was developed to modify a PDMS channel for enantioseparation of chiral compounds. After the PDMS microchip was filled with NE solution, poly(norepinephrine) (PNE) film was gradually formed and deposited on the inner wall of microchannel as permanent coating via the oxidation of NE by the oxygen dissolved in the solution. Due to possessing plentiful catechol and amine functional groups, the PNE-coated PDMS microchip exhibited much better wettability, more stable and suppressed EOF, and less nonspecific adsorption. The water contact angle and EOF of PNE-coated PDMS substrate were measured to be 13° and 1.68 × 10(-4) cm(2) V(-1) s(-1) , compared to those of 108° and 2.24 × 10(-4) cm(2) V(-1) s(-1) from the untreated one, respectively. Different kinds of chiral compounds, such as amino acid enantiomer, drug enantiomer, and peptide enantiomer were efficiently separated utilizing a separation length of 37 mm coupled with in-column amperometric detection on the PNE-coated PDMS microchips. This facile mussel-inspired PNE-based microchip system exhibited strong recognition ability, high-performance, admirable reproducibility, and stability, which may have potential use in the complex biological analysis. PMID:26970233

  9. Impact of Chiral Bioanalytical Methods on the Bioequivalence of Ibuprofen Products Containing Ibuprofen Lysinate and Ibuprofen Base.

    Science.gov (United States)

    García-Arieta, Alfredo; Ferrero-Cafiero, Juan Manuel; Puntes, Montse; Gich, Ignasi; Morales-Alcelay, Susana; Tarré, Maite; Font, Xavier; Antonijoan, Rosa Maria

    2016-05-01

    The purpose was to assess the impact of the use of a chiral bioanalytical method on the conclusions of a bioequivalence study that compared two ibuprofen suspensions with different rates of absorption. A comparison of the conclusion of bioequivalence between a chiral method and an achiral approach was made. Plasma concentrations of R-ibuprofen and S-ibuprofen were determined using a chiral bioanalytical method; bioequivalence was tested for R-ibuprofen and for S-ibuprofen separately and for the sum of both enantiomers as an approach for an achiral bioanalytical method. The 90% confidence interval (90% CI) that would have been obtained with an achiral bioanalytical method (90% CI: Cmax: 117.69-134.46; AUC0 (t) : 104.75-114.45) would have precluded the conclusion of bioequivalence. This conclusion cannot be generalized to the active enantiomer (90% CI: Cmax : 103.36-118.38; AUC0 (t) : 96.52-103.12), for which bioequivalence can be concluded, and/or the distomer (90% CI: Cmax : 132.97-151.33; AUC0 (t) : 115.91-135.77) for which a larger difference was observed. Chiral bioanalytical methods should be required when 1) the enantiomers exhibit different pharmacodynamics and 2) the exposure (AUC or Cmax ) ratio of enantiomers is modified by a difference in the rate of absorption. Furthermore, the bioequivalence conclusion should be based on all enantiomers, since the distomer(s) might not be completely inert, in contrast to what is required in the current regulatory guidelines. In those cases where it is unknown if the ratio between enantiomers is modified by changing the rate of absorption, chiral bioanalytical methods should be employed unless enantiomers exhibit the same pharmacodynamics. Chirality 28:429-433, 2016. © 2016 Wiley Periodicals, Inc. PMID:27094918

  10. Enantioselective Recognition of Chiral Carboxylic Acids by a β-Amino Acid and 1,10-Phenanthroline Based Chiral Fluorescent Sensor

    Directory of Open Access Journals (Sweden)

    Yonghong Zhang

    2015-05-01

    Full Text Available A novel chiral 1,10-phenanthroline-based fluorescent sensor was designed and synthesized from optical active β-amino acids. It used 1,10-phenanthroline moiety as a fluorescent signaling site and binding site, with optically active β-amino acids as a chiral barrier site. Notably, the optically active β-amino acids were obtained by a Lewis base catalyzed hydrosilylation of β-enamino esters according to our former work. The chiral sensor has been used to conduct the enantioselective recognition of chiral mono and dicarboxylic acids derivatives. Using this fluorescent sensor, a moderate “turn-off” fluorescence-diminishment response towards enantiomer of tartaric acids, and proline was observed. It found that l-enantiomers quench the chiral fluorescence sensor more efficiently than d-enantiomers due to the absolute configuration of the β-amino acid.

  11. Novel Composite Materials for Chiral Separation from Cellulose and Barium Sulfate

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2013-01-01

    Full Text Available Cellulose was dissolved in an aqueous solution of sodium hydroxide (NaOH and urea followed by the addition of barium sulfate (BaSO4 to yield the BaSO4/cellulose composite particles. The morphology, particle size, and BaSO4 content of the composite particles were adjusted by controlling the feed ratio of cellulose and BaSO4. The cellulose within the composite particles then reacted with 3,5-dimethylphenyl isocyanate. The resulting materials were utilized as the chiral stationary phases (CSPs whose enantioseparation capabilities were evaluated by various chiral analytes. Due to the mechanical enhancement effect of BaSO4, the composite particles could be applied to the chromatographic packing materials.

  12. Chiral separation of benzoporphyrin derivative mono- and diacids by laser induced fluorescence-capillary electrophoresis.

    Science.gov (United States)

    Peng, Xuejun; Sternberg, Ethan; Dolphin, David

    2002-01-01

    A method for the separation of benzoporphyrin derivative mono- and diacid (BPDMA, BPDDA) enantiomers by laser induced fluorescence-capillary electrophoresis (LIF-CE) has been developed. By using 300 mM borate buffer, pH 9.2, 25 mM sodium cholate and 10% acetronitrile as electrolyte, +10 kV electrokinetic sampling injection of 2 s and an applied +20 kV voltage across the ends of a 37 cm capillary (30 cm to the detector, 50 microm ID), all six BPD stereoisomers were baseline-separated within 20 min. Formation constants, free electrophoretic and complexation mobilities with borate and cholate were determined based on dynamic complexation capillary electrophoresis theory. The BPD enantiomers can be quantitatively determined in the range of 10(-2)-10(-5) mg mL(-1). The correlation coefficients (r2) of the least-squares linear regression analysis of the BPD enantiomers are in the range of 0.9914-0.9997. Their limits of detection are 2.18-3.5 x 10(-3) mg mL(-1). The relative standard deviations for the separation were 2.90-4.64% (n = 10). In comparison with high-performance liquid chromatography (HPLC), CE has better resolution and efficiency. This separation method was successfully applied to the BPD enantiomers obtained from a matrix of bovine serum and from liposomally formulated material as well as from studies with rat, dog and human microsomes. PMID:11824627

  13. Application of Countercurrent Chromatography on Chiral Separation%逆流色谱技术在手性分离方面的应用

    Institute of Scientific and Technical Information of China (English)

    吕迎春; 樊竹青

    2014-01-01

    Countercurrent chromatography is a liquid -liquid partition chromatography,without the use of support body or carrier.It is of advantage for chiral separation.In this paper its recent application in chiral separation is reviewed.%逆流色谱是一种不用固态支撑体或载体的液液分配色谱技术,其分离原理具有手性制备性分离的优势。以近年采用逆流色谱技术对手性化合物分离的应用进行了综述。

  14. Enantioselective Recognition of Chiral Carboxylic Acids by a β-Amino Acid and 1,10-Phenanthroline Based Chiral Fluorescent Sensor

    OpenAIRE

    Yonghong Zhang; Fangzhi Hu; Bin Wang; Xiaomei Zhang; Chenjiang Liu

    2015-01-01

    A novel chiral 1,10-phenanthroline-based fluorescent sensor was designed and synthesized from optical active β-amino acids. It used 1,10-phenanthroline moiety as a fluorescent signaling site and binding site, with optically active β-amino acids as a chiral barrier site. Notably, the optically active β-amino acids were obtained by a Lewis base catalyzed hydrosilylation of β-enamino esters according to our former work. The chiral sensor has been used to conduct the enantioselective recognition ...

  15. Chiral Separation of Ephedrine and Pseudoephedrine by Capillary Electrophoresis%毛细管电泳技术分离麻黄碱和伪麻黄碱

    Institute of Scientific and Technical Information of China (English)

    高冲; 王明召

    2015-01-01

    设计了一篇反映现代化学内容的高中化学教学材料。通过用氧化石墨烯修饰毛细管柱分离麻黄碱和伪麻黄碱的研究实例,介绍毛细管电泳技术分离手性对映体的基本原理,内容涉及分子的手性、分子间作用力、氢键等高中化学知识,供一线高中化学教师用于教学实践。%Based on high school chemistry knowledge such as chiral molecules,intermolecu-lar forces and hydrogen bond,an instructional material about the basic principles of chiral separa-tions of the ephedrine-pseudoephedrine (E-PE)isomers by GO-coated capillary electrophoresis was designed,in order to extend high school chemistry.

  16. Relationship between chromatographic resolution and amide structure of chiral 2-hydroxy acids as O-(-)-menthoxycarbonylated diastereomeric derivatives for enantiomeric separation on achiral gas chromatography.

    Science.gov (United States)

    Cha, Eunju; Kim, Sohee; Lee, Kang Mi; Kim, Ho Jun; Kim, Ki Hun; Kwon, Oh-Seung; Park, Ki Duk; Lee, Jaeick

    2016-02-15

    The relationship between chromatographic resolution and amide structure of chiral 2-hydroxy acids as O-(-)-menthoxycarbonylated diastereomeric derivatives on achiral gas chromatography was investigated to elucidate the best diastereomeric conformation for enantiomeric separation of chiral 2-hydroxy acids. Thirteen chiral 2-hydroxy acids were converted into nine different diastereomeric O-(-)-menthoxycarbonylated amide derivatives using the primary, secondary and cyclic amines to achieve complete enantiomeric separation through an achiral column. Each enantiomeric pair of 2-hydroxy acids as O-(-)-menthoxycarbonylated tert-butylamide derivatives was resolved on both the DB-5 and DB-17 columns with resolution factors ranging from 1.7 to 4.8 and 1.7 to 3.4, respectively. The results revealed that the structure of the amide moiety is shown to significantly affect chromatographic resolution. In addition, O-(-)-menthoxycarbonylated tert-butylamide derivatives were shown to be the best diastereomeric conformations for enantiomeric separation of 2-hydroxy acids. When comparing with our previous O-trifluoroacetylated(-)-menthyl ester derivatization method, the present results suggested that size differences between groups attached to the chiral center and conformational rigidity can have stronger effects on resolution than the distance between chiral centers. The elution of R- and S-stereoisomers was affected by the class of amine; i.e., primary, secondary, or cyclic, regardless of the substituents on the amine group, the structure of the 2-hydroxy acid, and the polarity of the column. PMID:26800225

  17. High-performance liquid chromatographic separation of rolipram, bupivacaine and omeprazole using a tartardiamide-based stationary phase influence of flow rate and temperature on the enantioseparation.

    Science.gov (United States)

    da Silva Junior, Ivanildo José; Sartor, João Paulo; Rosa, Paulo César Pires; de Veredas, Vinícius; Barreto Júnior, Amaro Gomes; Santana, Cesar Costapinto

    2007-08-24

    Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled.

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

    Science.gov (United States)

    Zhang, Xue-Feng; Eggert, Sebastian

    2013-10-01

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

  19. Chiral EFT based nuclear forces: achievements and challenges

    Science.gov (United States)

    Machleidt, R.; Sammarruca, F.

    2016-08-01

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

  20. Chiral EFT based nuclear forces: Achievements and challenges

    CERN Document Server

    Machleidt, R

    2016-01-01

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

  1. Chiral separation of neonicotinoid insecticides by polysaccharide-type stationary phases using high-performance liquid chromatography and supercritical fluid chromatography.

    Science.gov (United States)

    Zhang, Cheng; Jin, Lixia; Zhou, Shanshan; Zhang, Yifan; Feng, Shuoli; Zhou, Qinyan

    2011-03-01

    The enantiomeric separations of three neonicotinoid insecticides (identified as compounds 1, 2, and 3) were performed on three polysaccharide-type chiral columns, that is, Chiralcel OD-H, Chiralpak AD-H, and Chiralpak IB, by high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). Effects of the modifier percentage and column temperature on chiral recognitions of chiral stationary phases were also studied. Both 1 and 2 could be resolved on all three columns selected, with the highest R(s) values obtained on Chiralpak AD-H and Chiralcel OD-H, respectively. However, satisfactory separation of the four stereoisomers of 3 was only achieved on Chiralcel OD-H. Considering the effects of ethanol on the values of k, α, and R(s), we concluded that hydrogen bonding, π-π, and/or dipole-dipole interactions might be all responsible for the chiral separation. In comparison to HPLC, a shorter run time was achieved for 1 and 2 by SFC. However, 3 could not be stereoselectively resolved using SFC. On the basis of the calculated thermodynamic parameters, we found that the separation processes of enantiomers of 1 and 2 were entropy controlled and enthalpy controlled, respectively.

  2. Carboxymethyl-β-cyclodextrin for Chiral Separation of Amino Acids Derivatized with Fluorescene-5-isothiocyanate by Capillary Electrophoresis and Laser-induced Fluorescence Detection

    Institute of Scientific and Technical Information of China (English)

    Yu Yun CHEN; Wei WANG; Wei Ping YANG; Zhu Jun ZHANG

    2004-01-01

    A method using carboxymethyl-β-cyclodextrin(CM-β-CD) as selector for chiral separation of amino acids by capillary electrophoresis and laser-induced fluorescence detection was studied. Resolution was better than that obtained byβ-CD or HP-β-CD.

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

    Science.gov (United States)

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

    2016-01-01

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

  4. Modelling of conditions for the enantiomeric separation of beta(2)-adrenergic sympathicomimetics by capillary electrophoresis using cyclodextrins as chiral selectors in a polyethylene glycol gel

    NARCIS (Netherlands)

    de Boer, T; Bijma, R; Ensing, K

    1999-01-01

    A two-factor central composite design was used to determine a mathematical model for prediction of the optimal conditions for the separation of the enantiomers of some widely used beta(2)-sympathicomimetic drugs (beta(2)-agonists) by capillary electrophoresis using cyclodextrins (CD) as a chiral sel

  5. Research progress in Cellulose-based Chiral Selectors%纤维素手性拆分剂的研究进展

    Institute of Scientific and Technical Information of China (English)

    宋洪浪

    2013-01-01

    文章介绍了几种纤维素类手性拆分剂以及其制备方法相关分离机理,综述了纤维素手性拆分剂的分离机理及其应用,重点地介绍纤维素手性固定相和纤维素膜的应用。%In this paper, several kinds of cellulose-based chiral selectors and its preparation methods were introduced , the application and separation mechanism of cellulose-based chiral selectors were summarized, and intensively emphasized on the applications of cellulose chiral stationary phase and cellulose membrane.

  6. Chiral retrieval method based on right circularly polarized and left circularly polarized waves

    International Nuclear Information System (INIS)

    The free-wave characterization of metamaterials is usually carried out by illuminating a sample with a linearly polarized plane electromagnetic wave. At points before and after the sample, sensors are introduced to measure the transverse components of the field, in order to compute the reflection and transmission coefficients related with the co- and cross-polar field components. Based on this information, retrieval algorithms allow parameters like rotation angle, effective chirality and refraction index to be calculated. Here we propose to use the transmission signals under illumination with plane circularly polarized waves, without sensing the reflection signal, to calculate the chirality parameter and the rotation angle due to the electromagnetic activity of the material. This new method, which allows a simpler characterization of a chiral slab, is applied to the study of metamaterials composed of both periodic and random distributions of metallic structures with chiral symmetry. The experimental results are contrasted with simulations and alternative measurements obtained using linearly polarized waves. (paper)

  7. Methodologies for the separation of chiral drugs by liquid chromatography: from analytical to preparative scale

    OpenAIRE

    Ribeiro, António E.; A. E. Rodrigues; Pais, L.S.

    2012-01-01

    The main goal of the present work is to clear demonstrate that the selection of the proper solvent composition is a key step for both analytical and preparative separations. A complete methodology developed in the last years inside the LSRE group will be described. Three real optimization case-studies will be presented: two non-steroidal anti-inflammatory drugs (the separation of ketoprofen and flurbiprofen enantiomers) and one antihypertensive drug (the separation of nadolol stereoisomers).

  8. Separators - Technology review: Ceramic based separators for secondary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Nestler, Tina; Schmid, Robert; Münchgesang, Wolfram; Bazhenov, Vasilii; Meyer, Dirk C. [Technische Universität Bergakademie Freiberg, Institut für Experimentelle Physik, Leipziger Str. 23, 09596 Freiberg (Germany); Schilm, Jochen [Fraunhofer-Institut für Keramische Technologien und Systeme IKTS, Winterbergstraße 28, 01277 Dresden (Germany); Leisegang, Tilmann [Fraunhofer-Technologiezentrum Halbleitermaterialien THM, Am St.-Niclas-Schacht 13, 09599 Freiberg (Germany)

    2014-06-16

    Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ('Energiewende') was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membrane - the separator - as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic-based

  9. Separators - Technology review: Ceramic based separators for secondary batteries

    International Nuclear Information System (INIS)

    Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ('Energiewende') was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membrane - the separator - as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic-based separators

  10. Facile Synthesis of Chiral Conjugated Polymer Based on BINOL Skeleton

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new type of chiral conjugated polymers 6a-d has been synthesized by the reaction of (R)-2,2'-dihydroxy-1,1'-binaphthyl-6,6'-dicarbaldehyde 5 with corresponding diamine in the presence of acetic acid.

  11. Chiral Separation of Ibuprofen by Supercritical Fluid Chromatography%超临界流体色谱手性分离布洛芬

    Institute of Scientific and Technical Information of China (English)

    HAN Soonkoo; ROW Kyungho

    2005-01-01

    The separation method using chiral stationary phase (CSP) for the preparation of enantioselective compound was widely used. In this work, supercritical fluid chromatography(SFC) was proposed to resolve the chiral mixtures. To determine the optimum operating conditions for the chiral separation of the racemic ibuprofen,the retention factors and resolutions with the change in pressure, temperature and the content of IPA (%, by volume)in supercritical CO2 were investigated. Experiments showed that the retention factor decreased with the increase of pressure and decrease in temperature. The retention factor was also influenced by the content of IPA in mobile phase, as the content of IPA in the supercritical fluid increased, the retention factor decreased. The resolution of the enantiomers became worse with the increase of IPA in the supercritical fluid. Through optimizing the experimental conditions, a SFC procedure with 13MPa, 311.15K and 4% IPA in CO2 was obtained. The peak shape of the enantiomers was symmetric with supercritical fluid chromatography when compared to the asymmetric peak shape obtained by the conventional liquid chromatography. This work demonstrated that the developed supercritical fluid chromatography procedure was suitable for the chiral separation of ibuprofen enantiomers.

  12. Direct enantioseparation of underivatized aliphatic 3-hydroxyalkanoic acids with a quinine-based zwitterionic chiral stationary phase.

    Science.gov (United States)

    Ianni, Federica; Pataj, Zoltán; Gross, Harald; Sardella, Roccaldo; Natalini, Benedetto; Lindner, Wolfgang; Lämmerhofer, Michael

    2014-10-10

    While aliphatic 2-hydroxyalkanoic acids have been more or less successfully enantioseparated with various chiral stationary phases by HPLC and GC, analogous applications on underivatized aliphatic 3-hydroxyalkanoic acids are completely absent in the scientific literature. With the aim of closing this gap, the enantioseparation of 3-hydroxybutyric acid, 3-hydroxydecanoic acid and 3-hydroxymyristic acid has been performed with two ion-exchange type chiral stationary phases (CSPs): one containing the anion-exchange type tert-butyl carbamoyl quinine chiral selector motif (Chiralpak QN-AX), and the other carrying the new zwitterionic variant based on trans-(S,S)-2-aminocyclohexanesulfonic acid-derivatized quinine carbamate (Chiralpak ZWIX(+)) as the chiral selector and enantiodiscriminating element, respectively. The zwitterionic enantiorecognition material provided better results in terms of enantioselectivity and resolution compared to the anion-exchanger CSP at reduced retention times due to the intramolecular counterion effect imposed by the sulfonic acid moiety and its competition with the 3-hydroxyalkanoic acid analyte for ionic interaction at the quininium-anion exchanger site. It is thus recommended as the CSP of first choice for enantioseparations of the class of aliphatic 3-hydroxyalkanoic acids. With use of polar organic eluent composed of ACN/MeOH/AcOH - 95/5/0.05 (v/v/v), a good compromise in terms of analysis time and enantioresolution quality was accomplished. The major experimental variables have been investigated for optimization of the resolution and allowed to derive information on the enantiorecognition mechanism. Corresponding Chiralpak ZWIX(-), based on pseudo-enantiomeric selector derived from quinidine and trans-(R,R)-2-aminocyclohexanesulfonic acid with opposite configurations provided reversed enantiomer elution orders. It has further to be stressed that these separations can be obtained with mass spectrometry compatible mobile phases.

  13. 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.

  14. Computer Based Analytical Simulations of the Chiral Hadronic Processes

    OpenAIRE

    Aleksejevs, A.; Butler, M

    2007-01-01

    The availability of computational modeling tools for subatomic physics (Form, FeynArts, FormCalc, and FeynCalc) has made it possible to perform sophisticated calculations in perturbative quantum field theory. We have adapted these packages in order to apply them to the effective chiral field theory of hadronic interactions. A detailed description of this Computational Hadronic Model is presented here, along with sample calculations.

  15. Computer-based analytical simulations of chiral hadronic processes

    Science.gov (United States)

    Aleksejevs, A.; Butler, M.

    2010-03-01

    The availability of computational modeling tools for subatomic physics (Form, FeynArts, FormCalc and FeynCalc) has made it possible to perform sophisticated calculations in perturbative quantum field theory. We have adapted these packages in order to apply them to the effective chiral field theory of hadronic interactions. A detailed description of this computational hadronic model is presented here, along with sample calculations.

  16. Pharmaceutical-enantiomers resolution using immobilized polysaccharide-based chiral stationary phases in supercritical fluid chromatography.

    Science.gov (United States)

    De Klerck, Katrijn; Vander Heyden, Yvan; Mangelings, Debby

    2014-02-01

    Since their introduction on the market the applicability of immobilized polysaccharide-based chiral stationary phases in high-performance liquid chromatography has been thoroughly investigated. These immobilized phases have the benefit to be applicable with a wide range of modifiers, potentially extending the application range of the polysaccharide-based stationary phases. Because an increasing number of stationary phases are being introduced in the field of chiral chromatography it is important to evaluate their enantioselectivity in different techniques in order to get an idea about their applicability. In this study, three immobilized chiral polysaccharide-based stationary phases (Chiralpak IA, IB, and IC) are evaluated in supercritical fluid chromatography (SFC) with a test set of pharmaceutical racemates. This is done in a three-fold manner: their performance is evaluated (1) using traditional modifiers, (2) using mixtures of atypical modifiers, and (3) the results were compared to those on coated stationary phases with an equivalent chiral selector. To get a visual overview of the enantioselective patterns of the different chromatographic systems (mobile and stationary phase combinations), a Principal Component Analysis is performed, which allows determining the (dis)similarity between individual systems. To assess the complementarity cumulative success rates are determined. The immobilized chiral stationary phases prove to yield high cumulative success rates. PMID:24438871

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

    Science.gov (United States)

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

    2016-09-01

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

  18. Enantioselective recognition and separation of racemic 1-phenylethanol by a pair of 2D chiral coordination polymers.

    Science.gov (United States)

    Li, Zi-Jian; Yao, Jia; Tao, Qian; Jiang, Long; Lu, Tong-Bu

    2013-10-21

    A pair of 2D chiral coordination polymers were constructed through the self-assembly of a chiral metal-camphor-10-sulfonate salt and a bidentate linker, which show selective inclusion of S and R enantiomers of 1-phenylethanol respectively with an enantioselectivity of 9:1. PMID:24083956

  19. Cyclodextrine Screening for the Chiral Separation of Amlodipine Enantiomers by Capillary Electrophoresis

    OpenAIRE

    Gabriel Hancu; Monica Budău; Lajos Kristóf Kántor; Anca Cârje

    2015-01-01

    Purpose: Amlodipine is a long acting, dihydropyridine type calcium channel blocker frequently used in the treatment of hypertension and coronary insufficiency. The calcium channel blocking activity resides primarily in the S-amlodipine enantiomer, while R-amlodipine is a potent inhibitor of smooth muscle cell migration. Methods: In this study capillary electrophoresis was applied for the enantiomeric separation of amlodipine using different native and derivatized; neutral and charged cyclo...

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

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    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 mal...

  1. 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.

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

    Institute of Scientific and Technical Information of China (English)

    隗兰华; 何永炳; 徐括喜; 刘顺英; 孟令芝

    2005-01-01

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

  3. Genetic algorithm based separation cascade optimization

    International Nuclear Information System (INIS)

    The conventional separation cascade design procedure does not give an optimum design because of squaring-off, variation of flow rates and separation factor of the element with respect to stage location. Multi-component isotope separation further complicates the design procedure. Cascade design can be stated as a constrained multi-objective optimization. Cascade's expectation from the separating element is multi-objective i.e. overall separation factor, cut, optimum feed and separative power. Decision maker may aspire for more comprehensive multi-objective goals where optimization of cascade is coupled with the exploration of separating element optimization vector space. In real life there are many issues which make it important to understand the decision maker's perception of cost-quality-speed trade-off and consistency of preferences. Genetic algorithm (GA) is one such evolutionary technique that can be used for cascade design optimization. This paper addresses various issues involved in the GA based multi-objective optimization of the separation cascade. Reference point based optimization methodology with GA based Pareto optimality concept for separation cascade was found pragmatic and promising. This method should be explored, tested, examined and further developed for binary as well as multi-component separations. (author)

  4. Asymmetric Michael Reaction of Malononitrile Catalyzed by Chiral Ru(Ⅱ) Complex and Achiral Base

    Institute of Scientific and Technical Information of China (English)

    MA Ya-Ping; XING Zhi-Kui; ZHU Jin; CUI Xin; CUN Lin-Feng; DENG Jin-Gen

    2003-01-01

    @@ Michael addition reactions represent one of the most important carbon-carbon bond forming reactions in modern synthetic organic chemistry. [1 ~3] We achieved catalytic enantioselective Michael addition reactions of malononitrile with chiral vicinal diamine-Ru(Ⅱ) complex in the presence of achiral base. High yields and moderate ee were observed.

  5. Optimization of chiral lattice based metastructures for broadband vibration suppression using genetic algorithms

    Science.gov (United States)

    Abdeljaber, Osama; Avci, Onur; Inman, Daniel J.

    2016-05-01

    One of the major challenges in civil, mechanical, and aerospace engineering is to develop vibration suppression systems with high efficiency and low cost. Recent studies have shown that high damping performance at broadband frequencies can be achieved by incorporating periodic inserts with tunable dynamic properties as internal resonators in structural systems. Structures featuring these kinds of inserts are referred to as metamaterials inspired structures or metastructures. Chiral lattice inserts exhibit unique characteristics such as frequency bandgaps which can be tuned by varying the parameters that define the lattice topology. Recent analytical and experimental investigations have shown that broadband vibration attenuation can be achieved by including chiral lattices as internal resonators in beam-like structures. However, these studies have suggested that the performance of chiral lattice inserts can be maximized by utilizing an efficient optimization technique to obtain the optimal topology of the inserted lattice. In this study, an automated optimization procedure based on a genetic algorithm is applied to obtain the optimal set of parameters that will result in chiral lattice inserts tuned properly to reduce the global vibration levels of a finite-sized beam. Genetic algorithms are considered in this study due to their capability of dealing with complex and insufficiently understood optimization problems. In the optimization process, the basic parameters that govern the geometry of periodic chiral lattices including the number of circular nodes, the thickness of the ligaments, and the characteristic angle are considered. Additionally, a new set of parameters is introduced to enable the optimization process to explore non-periodic chiral designs. Numerical simulations are carried out to demonstrate the efficiency of the optimization process.

  6. Liquid chromatographic resolution of mexiletine and its analogs on crown ether-based chiral stationary phases.

    Science.gov (United States)

    Jin, Kab Bong; Kim, Hee Eun; Hyun, Myung Ho

    2014-05-01

    Mexiletine, an effective class IB antiarrhythmic agent, and its analogs were resolved on three different crown ether-based chiral stationary phases (CSPs), one (CSP 1) of which is based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid and the other two (CSP 2 and CSP 3) are based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6. Mexiletine was resolved with a resolution (R(S)) of greater than 1.00 on CSP 1 and CSP 3 containing residual silanol group-protecting n-octyl groups on the silica surface, but with a resolution (R(S)) of less than 1.00 on CSP 2. The chromatographic behaviors for the resolution of mexiletine analogs containing a substituted phenyl group at the chiral center on the three CSPs were quite dependent on the phenoxy group of analytes. Namely, mexiletine analogs containing 2,6-dimethylphenoxy, 3,4-dimethylphenoxy, 3-methylphenoxy, 4-methylphenoxy, and a simple phenoxy group were resolved very well on the three CSPs even though the chiral recognition efficiencies vary with the CSPs. However, mexiletine analogs containing 2-methylphenoxy group were not resolved at all or only slightly resolved. Among the three CSPs, CSP 3 was found to show the highest chiral recognition efficiencies for the resolution of mexiletine and its analogs, especially in terms of resolution (R(S)). PMID:24677299

  7. A new chiral binaphthalene-based fluorescence polymer sensor for the highly enantioselective recognition of phenylalaninol.

    Science.gov (United States)

    Wei, Guo; Zhang, Shuwei; Dai, Chunhui; Quan, Yiwu; Cheng, Yixiang; Zhu, Chengjian

    2013-11-18

    A new (S)-binaphthalene-based polymer (P-1) was synthesized by the polymerization of 5,5'-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(2-hydroxy-3-(piperidin-1-ylmethyl) benzaldehyde (M-1) with (S)-2,2'-dimethoxy-(1,1'-binaphthalene)-3,3'-diamine (M-2) through the formation of a Schiff base; the corresponding chiral polymer (P-2) could be obtained by the reduction of polymer P-1 with NaBH4 . Chiral polymer P-1 exhibited a remarkable "turn-on" fluorescence-enhancement response towards (D)-phenylalaninol and excellent enantioselective recognition behavior with enantiomeric fluorescence difference ratios (ef) as high as 8.99. More importantly, chiral polymer P-1 displays a bright blue fluorescence color change upon the addition of (D)-phenylalaninol under a commercially available UV lamp, which can be clearly observed by the naked eye. On the contrary, chiral polymer P-2 showed weaker enantioselective fluorescence ability towards the enantiomers of phenylalaninol. PMID:24123510

  8. Role of substituents in cyclodextrin derivatives for enantioselective gas chromatographic separation of chiral terpenoids in the essential oils of Mentha spicata.

    Science.gov (United States)

    Pragadheesh, V S; Yadav, Anju; Chanotiya, Chandan Singh

    2015-10-01

    Enantioselective GC-FID and enantioselective GC-MS have been utilized under temperature gradient mode with differently substituted heptakis- and octakis-cyclodextrins to achieve the resolution of chiral terpenoids in the essential oil of indigenously grown cultivars of Mentha spicata. Modified cyclodextrins were derivatized in GC column for the separation of chiral terpenoids. A 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin doped into 14% cyanopropylphenyl/86%dimethylpolysiloxane (TBDE-β-CD) showed good enantioselectivity for all the studied chiral compounds excluding carvone. Carvone enantiomers were well resolved in 2,3-diacetoxy-6-tert-butyldimethylsilyl-β-cyclodextrin column (TBDA-β-CD) with enantioseparation (Es) of 1.006. A TBDE-β-CD provides maximum enantiomeric separation for β-pinene (Es 1.038), sabinene (Es 1.051), limonene (Es 1.045), isomenthone (Es 1.029) and α-terpineol (Es 1.014). Furthermore, enantiomer elution order reversal was observed for sabinene, menthone, terpinen-4-ol and menthol while changing from β- to γ-cyclodextrin phase. Carvone exhibits enantiomer elution order reversal by changing substituents i.e., methyl to acetyl at 2- & 3- position of the cyclodextrin derivative. Chiral constituents such as (+)-isomenthone, (-)-menthone, (1R,2S,5R)-(-)-menthol and (4S)-(+)-piperitone exist as a single enantiomer with >99% excess. Existence of (R)-(+)-limonene and (S)-(+)-carvone enantiomers has been proven first time in M. spicata essential oils and can be used as the marker for Indian origin.

  9. Role of substituents in cyclodextrin derivatives for enantioselective gas chromatographic separation of chiral terpenoids in the essential oils of Mentha spicata.

    Science.gov (United States)

    Pragadheesh, V S; Yadav, Anju; Chanotiya, Chandan Singh

    2015-10-01

    Enantioselective GC-FID and enantioselective GC-MS have been utilized under temperature gradient mode with differently substituted heptakis- and octakis-cyclodextrins to achieve the resolution of chiral terpenoids in the essential oil of indigenously grown cultivars of Mentha spicata. Modified cyclodextrins were derivatized in GC column for the separation of chiral terpenoids. A 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin doped into 14% cyanopropylphenyl/86%dimethylpolysiloxane (TBDE-β-CD) showed good enantioselectivity for all the studied chiral compounds excluding carvone. Carvone enantiomers were well resolved in 2,3-diacetoxy-6-tert-butyldimethylsilyl-β-cyclodextrin column (TBDA-β-CD) with enantioseparation (Es) of 1.006. A TBDE-β-CD provides maximum enantiomeric separation for β-pinene (Es 1.038), sabinene (Es 1.051), limonene (Es 1.045), isomenthone (Es 1.029) and α-terpineol (Es 1.014). Furthermore, enantiomer elution order reversal was observed for sabinene, menthone, terpinen-4-ol and menthol while changing from β- to γ-cyclodextrin phase. Carvone exhibits enantiomer elution order reversal by changing substituents i.e., methyl to acetyl at 2- & 3- position of the cyclodextrin derivative. Chiral constituents such as (+)-isomenthone, (-)-menthone, (1R,2S,5R)-(-)-menthol and (4S)-(+)-piperitone exist as a single enantiomer with >99% excess. Existence of (R)-(+)-limonene and (S)-(+)-carvone enantiomers has been proven first time in M. spicata essential oils and can be used as the marker for Indian origin. PMID:26310896

  10. Separations Science Data Base: an abstractor's manual

    International Nuclear Information System (INIS)

    The Separations Science Data Base, designed specifically for the retrieval of information needed in chemical separations problems (i.e., how to perform a given separation under given conditions), is described. The procedure for entering records into the data base is given. The initial entries are concerned primarily with liquid-liquid extraction and liquid-solid ion exchange methods for metal ions and salts; however, the data base is constructed so that almost any separations process can be accommodated. Each record is indexed with information provided under the following fields: author; title; publication source; date of publication; organization performing and/or sponsoring the work; brief abstract of the work; abstract number if the work has been so referenced, and/or abstractor's initials; type of separation system used (e.g., flotation); specific or generic name of the separation agent used (e.g., acetylacetone); list of substances separated (e.g., gold, copper); qualitative description of the supporting medium or matrix containing the substances before separation (e.g., nitrate); type of literature where the article was printed (e.g., book); and type of information that the article contains. Each of these fields may be searched independently of the others (or in combination), and the last six fields contain specific key words that are listed on the input form. Definitions are provided for the 39 information terms

  11. Catalytic Enantioselective Olefin Metathesis in Natural Product Synthesis. Chiral Metal-Based Complexes that Deliver High Enantioselectivity and More

    Science.gov (United States)

    Malcolmson, Steven J.; Meek, Simon J.; Zhugralin, Adil R.

    2012-01-01

    Chiral olefin metathesis catalysts enable chemists to access enantiomerically enriched small molecules with high efficiency; synthesis schemes involving such complexes can be substantially more concise than those that would involve enantiomerically pure substrates and achiral Mo alkylidenes or Ru-based carbenes. The scope of research towards design and development of chiral catalysts is not limited to discovery of complexes that are merely the chiral versions of the related achiral variants. A chiral olefin metathesis catalyst, in addition to furnishing products of high enantiomeric purity, can offer levels of efficiency, product selectivity and/or olefin stereoselectivity that are unavailable through the achiral variants. Such positive attributes of chiral catalysts (whether utilized in racemic or enantiomerically enriched form) should be considered as general, applicable to other classes of transformations. PMID:19967680

  12. Direct high-performance liquid chromatographic separation of the enantiomers of an aromatic amine and four aminoalcohols using polysaccharide chiral stationary phases and acidic additive.

    Science.gov (United States)

    Caccamese, Salvatore; Bianca, Salvatore; Carter, Guy T

    2007-08-01

    The HPLC enantiomeric separation of N-benzyl-alpha-methyl-benzylamine, phenylalaninol, tryptophanol, 2 (diphenylhydroxymethyl)pyrrolidine, and isoproterenol was accomplished in the normal-phase mode using two polysaccharide-derived chiral stationary phases (CSPs) and various n-hexane/2-propanol mobile phases with acidic (TFA) or basic (DEA) additive. The compounds were separated without any derivatization and separation factor range between 2.09 and 1.09 with resolution factor 3.4 and 0.4, respectively. The best separation of the enantiomers of the amine was achieved on amylose tris (3, 5-dimethylphenylcarbamate) CSP with TFA additive in the mobile phase; in acidic conditions, instead, the best enantioseparation of the aminoalcohols was achieved on cellulose tris (3, 5-dimethylphenilcarbamate). A long equilibration time of the CSP when switching from an undoped mobile phase to a doped one is required to obtain reproducible results. PMID:17568428

  13. Chiral Gravitational Waves from Chiral Fermions

    CERN Document Server

    Anber, Mohamed M

    2016-01-01

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

  14. Single-walled carbon nanotube-based polymer monoliths for the enantioselective nano-liquid chromatographic separation of racemic pharmaceuticals.

    Science.gov (United States)

    Ahmed, Marwa; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Su, Dawei; Wang, Guoxiu; Ostrikov, Kostya Ken; Ghanem, Ashraf

    2014-09-19

    Single-walled carbon nanotubes were encapsulated into different polymer-based monolithic backbones. The polymer monoliths were prepared via the copolymerization of 20% monomers, glycidyl methacrylate, 20% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) or 16.4% monomers (16% butyl methacrylate, 0.4% sulfopropyl methacrylate), 23.6% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) along with 6% single-walled carbon nanotubes aqueous suspension. The effect of single-walled carbon nanotubes on the chiral separation of twelve classes of pharmaceutical racemates namely; α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs was investigated. The enantioselective separation was carried out under multimodal elution to explore the chiral recognition capabilities of single-walled carbon nanotubes using reversed phase, polar organic and normal phase chromatographic conditions using nano-liquid chromatography. Baseline separation was achieved for celiprolol, chlorpheniramine, etozoline, nomifensine and sulconazole under multimodal elution conditions. Satisfactory repeatability was achieved through run-to-run, column-to-column and batch-to-batch investigations. Our findings demonstrate that single-walled carbon nanotubes represent a promising stationary phase for the chiral separation and may open the field for a new class of chiral selectors.

  15. Composite separators and redox flow batteries based on porous separators

    Science.gov (United States)

    Li, Bin; Wei, Xiaoliang; Luo, Qingtao; Nie, Zimin; Wang, Wei; Sprenkle, Vincent L.

    2016-01-12

    Composite separators having a porous structure and including acid-stable, hydrophilic, inorganic particles enmeshed in a substantially fully fluorinated polyolefin matrix can be utilized in a number of applications. The inorganic particles can provide hydrophilic characteristics. The pores of the separator result in good selectivity and electrical conductivity. The fluorinated polymeric backbone can result in high chemical stability. Accordingly, one application of the composite separators is in redox flow batteries as low cost membranes. In such applications, the composite separator can also enable additional property-enhancing features compared to ion-exchange membranes. For example, simple capacity control can be achieved through hydraulic pressure by balancing the volumes of electrolyte on each side of the separator. While a porous separator can also allow for volume and pressure regulation, in RFBs that utilize corrosive and/or oxidizing compounds, the composite separators described herein are preferable for their robustness in the presence of such compounds.

  16. Chiral separation of cathinone derivatives used as recreational drugs by HPLC-UV using a CHIRALPAK® AS-H column as stationary phase.

    Science.gov (United States)

    Mohr, Stefan; Taschwer, Magdalena; Schmid, Martin G

    2012-06-01

    Cathinone derivatives gained high popularity on the recreational drugs market during the past 10 years. All these compounds are chiral, and the pharmacological potency of the enantiomers of these stimulants is supposed to differ. The goal of this research was to develop a reliable and easy-to-perform high-performance liquid chromatography ultraviolet method for the chiral separation of a set of 24 cathinone derivatives. A commercially available CHIRALPAK® AS-H column consisting of amylose tris [(S)-α-methylbenzylcarbamate] coated on 5-µm silica gel was found to be suitable to resolve a majority of the tested compounds. High-performance liquid chromatography measurements were performed in normal phase mode under isocratic conditions with a mobile phase consisting of hexane, isopropanol, and triethylamine at a flowrate of 1 ml/min. The ratio between hexane and isopropanol was optimized by means of three model substances. Under final conditions with a mobile phase of hexane, isopropanol, and triethylamine (97:3:0.1), 19 out of 24 compounds were successfully resolved into their enantiomers and detected at a wavelength of 254 nm. A correlation between the substituents of the nitrogen atom and the separation results are shown. Furthermore, enantiomer separation results of four cathinone derivatives were compared with the results of their amphetamine analogs. PMID:22544697

  17. Chiral N-phosphonyl imine chemistry:asymmetric additions of glycine enolate to diphenyl diamine-based phosphonyl imines

    Institute of Scientific and Technical Information of China (English)

    PINDI; Suresh; KATTAMURI; Padmanabha; V.

    2010-01-01

    Diphenyl diamine-based phosphonyl imines attached by the N-isopropyl group in the auxiliary have been synthesized in good yields under convenient reaction conditions.These new chiral N-phosphonyl imines can react with glycine enolate smoothly to give chiral α-β diamino esters in good yields(72%-90%) and up to excellent diastereoselectivity(>99:1 dr).By treatment with HBr,the chiral auxiliary can be readily removed.The absolute structure has been unambiguously determined by converting a product to a known sample.

  18. Tunable multi-band chiral metamaterials based on double-layered asymmetric split ring resonators

    Science.gov (United States)

    Jia, Xiuli; Wang, Xiaoou; Meng, Qingxin; Zhou, Zhongxiang

    2016-07-01

    We have numerically demonstrated chiral metamaterials based on double-layered asymmetric Au film with hollow out design of split ring resonators on either side of the polyimide. Multiple electric dipoles and magnetic dipoles resulted from parallel and antiparallel currents between the eight split ring resonators. Multi-band circular dichroism is found in the visible frequency regime by studying the transmission properties. Huge optical activity and the induced multi-band negative refractive index are obtained at resonance by calculating the optical activity and ellipticity of the transmitted E-fields. Chirality parameter and effective refractive index are retrieved to illustrate the tunable optical properties of the metamaterials. The underlying mechanisms for the observed circular dichroism are analyzed. These metamaterials would offer flexible electromagnetic applications in the infrared and visible regime.

  19. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    Science.gov (United States)

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

    2015-09-01

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

  20. 盐酸昂丹司琼的高效毛细管电泳手性分离%Chiral separation of ondansetron hydrochloride by capillary electrophoresis

    Institute of Scientific and Technical Information of China (English)

    高佳; 祝仕清; 牛长群

    2012-01-01

    目的:建立盐酸昂丹司琼的高效毛细管电泳的手性分离方法.方法:通过手性拆分剂的种类及浓度、缓冲液的pH及浓度、温度及电压的优化,选择最佳的手性分离条件.结果:最佳分离条件缓冲液为33 mmol·L-1三羟甲基氨基甲烷(Tris)(用磷酸调节pH 2.2,含30 mg· mL-1羧甲基-β-环糊精);检测波长为214 nm;电压为30 kV;温度为25℃,基线分离了盐酸昂丹司琼的2个对映体.结论:新建立的方法可用于这一新药研究开发过程中的产品质量控制.%Objective: To establish a capillary electrophoresis method for chiral separation of ondansetron hydrochloride. Methods: The kinds and concentration of cyclodextrin, the pH value and concentration of buffer, the voltage and temperature were selected to optimize the conditions of chiral separation. Results: The optimal separation conditions were a 33 mmol·L-1 Tris buffer containing carboxymethyl-β-cyclodextrin (30 mg·mL-1 ) , detection at 214 nm, voltage at 30 kV and separation temperature at 25℃. The separation of ondansetron hydrochloride enantiomers was achieved in the optimal conditions. Conclusion: The newly established method can be used in quality control of products in new drug development process.

  1. Catalytic Enantioselective Aryl Transfer to Aldehydes Using Chiral 2,2’-Bispyrrolidine-Based Salan Ligands

    Directory of Open Access Journals (Sweden)

    Yixiang Cheng

    2011-04-01

    Full Text Available Chiral C2-symmetric diamines have emerged as versatile auxiliaries or ligands in numerous asymmetric transformations. Chiral 2,2’-bispyrrolidine-based salan ligands were prepared and applied to the asymmetric aryl transfer to aldehydes with arylboronic acids as the source of transferable aryl groups. The corresponding diarylmethanols were obtained in high yields with moderate to good enantioselectivitives of up to 83% ee.

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

    Science.gov (United States)

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

    2012-05-18

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

  3. Chiral Electroweak Currents in Nuclei

    CERN Document Server

    Riska, D O

    2016-01-01

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

  4. Excitation migration along oligophenylenevinylene-based chiral stacks: delocalization effects on transport dynamics.

    Science.gov (United States)

    Beljonne, D; Hennebicq, E; Daniel, C; Herz, L M; Silva, C; Scholes, G D; Hoeben, F J M; Jonkheijm, P; Schenning, A P H J; Meskers, S C J; Phillips, R T; Friend, R H; Meijer, E W

    2005-06-01

    Atomistic models based on quantum-chemical calculations are combined with time-resolved spectroscopic investigations to explore the migration of electronic excitations along oligophenylenevinylene-based chiral stacks. It is found that the usual Pauli master equation (PME) approach relying on uncoherent transport between individual chromophores underestimates the excitation diffusion dynamics, monitored here by the time decay of the transient polarization anisotropy. A better agreement to experiment is achieved when accounting for excitation delocalization among acceptor molecules, as implemented in a modified version of the PME model. The same models are applied to study light harvesting and trapping in guest-host systems built from oligomers of different lengths. PMID:16852286

  5. Estudio de un absorbedor basado en metamaterial quiral Study of absorber based on chiral metamaterial

    Directory of Open Access Journals (Sweden)

    Perla Espinosa Diaz

    2011-06-01

    Full Text Available El presente trabajo estudia el comportamiento electromagnético de un dispositivo absorbedor con estructura metamaterial quiral. El dispositivo propuesto consiste en una estructura de planos paralelos, con rosetas metálicas implantadas, físicamente separadas por capas dieléctricas. Para demostrar el efecto absorbedor de tal estructura, se ejecuta una simulación básica, en la cual se hace incidir un haz gaussiano sobre el metamaterial quiral. Los resultados muestran que, para efectos prácticos, ocurre absorción total. Este comportamiento hace que la estructura propuesta se comporte como un "agujero negro espacial".The electromagnetic behavior of an absorber device with chiral metamaterial structure is studied. The proposed device is a structure formed by parallel planes with implanted metallic rosettes, physically separated by dielectric layers. In order to show the absorbing properties of such structure, a basic simulation is run, in which a gaussian beam is fed incident to the chiral metamaterial. Results show that there is, for practical purposes, full absorption. This behavior makes the proposed structure behave as a "spatial black hole".

  6. CMAC Based Color Separation in Printing Images

    Institute of Scientific and Technical Information of China (English)

    WANG Yong-gang; YANG Jie; DING Yong-sheng

    2005-01-01

    To over come the drawbacks existing in current measurement methods for detecting and controlling colors in printing process, a new model for color separation and dot recognition is proposed from a view of digital image processing and patter recognition. In this model, firstly data samples are collected from some color patches by the Fuzzy C-Means (FCM)method; then a classifier based on the Cerebellar Model Articulation Controller (CMAC) is constructed which is used to recognize color pattern of each pixel in a microscopic halftone image. The principle of color separation and the algorithm model are introduced and the experiments show the effectiveness of the CMAC-based classifier as opposed to the BP network.

  7. Chiral streamers

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  8. Chiral streamers

    Science.gov (United States)

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

    2015-10-01

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

  9. Chiral atomically thin films

    Science.gov (United States)

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

    2016-06-01

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

  10. Electromagnetic Response of the Chiral Magnetic Effect in Weyl Semimetals

    OpenAIRE

    Barnes, Edwin; Heremans, J. J.; Minic, Djordje

    2016-01-01

    Weyl semimetals are predicted to realize the three-dimensional axial anomaly first discussed in particle physics. The anomaly leads to unusual transport phenomena such as the chiral magnetic effect in which an applied magnetic field induces a current parallel to the field. Here we investigate diagnostics of the axial anomaly based on the fundamental equations of axion electrodynamics. We find that materials with Weyl nodes of opposite chirality and finite energy separation immersed in a unifo...

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

    Institute of Scientific and Technical Information of China (English)

    Zhi Gang Zhao; Xing Li Liu; Yi Zhong

    2008-01-01

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

  12. On the Biological Advantage of Chirality

    CERN Document Server

    Gilat, G

    1999-01-01

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

  13. Chiral Synthons in Pesticide Syntheses

    NARCIS (Netherlands)

    Feringa, Bernard

    1988-01-01

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

  14. A new chiral derivatizing agent for the HPLC separation of α-amino acids on a standard reverse-phase column.

    Science.gov (United States)

    Kotthaus, A F; Altenbach, H-J

    2011-02-01

    A new chiral derivatizing agent for α-amino acids is described which leads to diastereomers that can be separated by reverse-phase HPLC with direct detection by a diode array detector. The main advantage of the presented procedure is the fact that an excess of the derivatizing reagent can be employed as the product exhibits an absorption maximum at 360 nm, while the reagent has its absorption maximum at 260 nm. Therefore, it is possible to suppress the reagent signal by a detection wavelength of 400 nm leading to an easy and general method for the enantioseparation of a mixture of DL-amino acids and the determination of the enantiomeric purity of α-amino acid as exemplified by 16 different α-amino acids.

  15. Modeling Textural Processes during Self-Assembly of Plant-Based Chiral-Nematic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Yogesh K. Murugesan

    2010-12-01

    Full Text Available Biological liquid crystalline polymers are found in cellulosic, chitin, and DNA based natural materials. Chiral nematic liquid crystalline orientational order is observed frozen-in in the solid state in plant cell walls and is known as a liquid crystal analogue characterized by a helicoidal plywood architecture. The emergence of the plywood architecture by directed chiral nematic liquid crystalline self assembly has been postulated as the mechanism that leads to optimal cellulose fibril organization. In natural systems, tissue growth and development takes place in the presence of inclusions and secondary phases leaving behind characteristic defects and textures, which provide a unique testing ground for the validity of the liquid crystal self-assembly postulate. In this work, a mathematical model, based on the Landau-de Gennes theory of liquid crystals, is used to simulate defect textures arising in the domain of self assembly, due to presence of secondary phases representing plant cells, lumens and pit canals. It is shown that the obtained defect patterns observed in some plant cell walls are those expected from a truly liquid crystalline phase. The analysis reveals the nature and magnitude of the viscoelastic material parameters that lead to observed patterns in plant-based helicoids through directed self-assembly. In addition, the results provide new guidance to develop biomimetic plywoods for structural and functional applications.

  16. Development and validation of a RP-UHPLC-ESI-MS/MS method for the chiral separation and determination of flavanone, naringenin and hesperetin enantiomers.

    Science.gov (United States)

    Baranowska, Irena; Hejniak, Judyta; Magiera, Sylwia

    2016-10-01

    A quick and sensitive RP-UHPLC-ESI-MS/MS method for the separation of flavanone, naringenin and hesperetin enantiomers was developed. The separation of analytes was performed using a Chiralpak AD-3R column, and methanol was used as the mobile phase. Detection was carried out using a triple quadrupole tandem mass spectrometer with an electrospray ionisation source. Positive ionisation and multiple reaction monitoring (MRM) were used. The developed method showed satisfactory linearity with determination coefficients greater than 0.996 in the concentration ranges of 2.5-100.0ngmL(-1) for naringenin and flavanone enantiomers and 0.5-100.0ngmL(-1) for hesperetin enantiomers. The limits of quantification varied from 0.1 to 2.0ngmL(-1). The intra-day and inter-day precisions were below 15%, and the accuracy varied from -13.6% to 13.5%. The described method was successfully applied for the chiral separation and determination of flavonoid enantiomers in real samples of spices and herbal root. Due to the occurrence of the natural compounds in the forms of free aglycones and their glycosides, these samples were subjected to hydrolysis in order to obtain free aglycones from the glycosylated forms. Acid and enzymatic hydrolysis techniques were also compared. In the course of this study, the enzymatic hydrolysis technique was selected. PMID:27474296

  17. Nanocellulose 3, 5-Dimethylphenylcarbamate Derivative Coated Chiral Stationary Phase: Preparation and Enantioseparation Performance.

    Science.gov (United States)

    Zhang, Xiaoli; Wang, Litao; Dong, Shuqing; Zhang, Xia; Wu, Qi; Zhao, Liang; Shi, Yanping

    2016-05-01

    Nanocrystalline cellulose (NCC) with high surface area and high ordered crystalline structure was prepared from microcrystalline cellulose (MCC) under the hydrolysis of sodium hypochlorite. NCC was further reacted with 3,5-dimethylphenyl isocyanate to obtain the nanocellulose derivative, and then coated successfully on the surface of silica gel to a prepared NCC-coated chiral stationary phase (CSP) as a new kind of chiral separation material. Similarly, MCC derivative-coated CSP was also prepared as contrast. The chiral separation performance of NCC-based CSP was evaluated and compared with MCC-based CSP by high-performance liquid chromatography. Moreover, the effects of the alcohol modifiers, mobile phase additives, and flow rates on chiral separations were investigated in detail. The results showed that 10 chiral compounds were separated on NCC-based CSP with better peak shape and higher column efficiency than MCC-based CSP, which confirmed that NCC-based CSP was a promising packing material for the resolution of chiral compounds.Chirality 28:376-381, 2016. © 2016 Wiley Periodicals, Inc. PMID:26949227

  18. Nanocellulose 3, 5-Dimethylphenylcarbamate Derivative Coated Chiral Stationary Phase: Preparation and Enantioseparation Performance.

    Science.gov (United States)

    Zhang, Xiaoli; Wang, Litao; Dong, Shuqing; Zhang, Xia; Wu, Qi; Zhao, Liang; Shi, Yanping

    2016-05-01

    Nanocrystalline cellulose (NCC) with high surface area and high ordered crystalline structure was prepared from microcrystalline cellulose (MCC) under the hydrolysis of sodium hypochlorite. NCC was further reacted with 3,5-dimethylphenyl isocyanate to obtain the nanocellulose derivative, and then coated successfully on the surface of silica gel to a prepared NCC-coated chiral stationary phase (CSP) as a new kind of chiral separation material. Similarly, MCC derivative-coated CSP was also prepared as contrast. The chiral separation performance of NCC-based CSP was evaluated and compared with MCC-based CSP by high-performance liquid chromatography. Moreover, the effects of the alcohol modifiers, mobile phase additives, and flow rates on chiral separations were investigated in detail. The results showed that 10 chiral compounds were separated on NCC-based CSP with better peak shape and higher column efficiency than MCC-based CSP, which confirmed that NCC-based CSP was a promising packing material for the resolution of chiral compounds.Chirality 28:376-381, 2016. © 2016 Wiley Periodicals, Inc.

  19. An Improved CO 2 Separation and Purification System Based on Cryogenic Separation and Distillation Theory

    OpenAIRE

    Gang Xu; Feifei Liang; Yongping Yang; Yue Hu; Kai Zhang; Wenyi Liu

    2014-01-01

    In this study, an improved CO 2 separation and purification system is proposed based on in-depth analyses of cryogenic separation and distillation theory as well as the phase transition characteristics of gas mixtures containing CO 2 . Multi-stage compression, refrigeration, and separation are adopted to separate the majority of the CO 2 from the gas mixture with relatively low energy penalty and high purity. Subsequently, the separated crude liquid CO 2 is distilled under high pressure and n...

  20. Synthesis and characterization of a tetranuclear copper(Ⅱ) complex with a chiral Schiff base ligand

    Institute of Scientific and Technical Information of China (English)

    Hua Xiang; Long Jiang; Huan-Yong Li; Xiao-Dan Zheng; YU Li

    2013-01-01

    The title complex l-[CuⅡ4(Hvap)2(vap)2(MeOH)2](ClO4)2 1 has been synthesized and characterized by EA,IR,TGA,solid-state CD spectra and X-ray single-crystal analyses (I-H2vap:a Schiff base ligand derived from the condensation of o-vanillin and 1-2-amino-3-phenyl-1-propanol).Complex 1 crystallizes in monoclinic system,chiral space group P21 with a=10.4257(18),b=21.695(4),c=15.721(3) (A),β =94.443(3)°,V=3545.1 (11) (A)3,Z =2,Cu4C7oH78N4O22Cl2,Mr =1652.42,Dc =1.548 g/cm3,F(0 0 0) =1704 and μ(MoKα) =1.338 mm-1.The final R =0.0682 and wR =0.1420 for 6170 observed reflections with I > 2σ(Ⅰ) and R =0.1775 and wR =0.1830 for all data.The structure of complex 1 contains a boat-shaped {Cu4O4} motif.The solid-state CD spectra confirm the chiral nature of complex 1.

  1. CHIRAL CONJUGATED OLIGOMER BASED ON 1,1'-BINOL WITH 3,3'-ACETYLENE-PHENYLENE-ACETYLENE SPACER

    Institute of Scientific and Technical Information of China (English)

    Tian-jun Liu; Ke-shen Zhang; Yong-jun Chen; Dong Wang; Chao-jun Li

    2001-01-01

    The 1,1'-binaphthol based oligomers 3 and 7 with 3,3'-acetylene-phenylene-acetylene spacer were prepared from BINOL 1. The high optical rotation value and CD spectra demonstrated the main chain chirality of the oligomer molecule. The UV-VIS and fluorescent spectra evidence the characteristics of conjugated structure. In comparison with oligomer 2 bearing 3,3'-acetylene spacer, the oligomers 3 and 7 have longer efficient conjugation segment, and their fluorescent quantum yields (φ) increased (0.60-0.65 versus 0.14). Extending the effective conjugation segment would improve the photophysical properties of chiral conjugated polymers.``

  2. RP-HPLC chiral separation of citalopram%反相高效液相色谱法拆分西酞普兰对映异构体*

    Institute of Scientific and Technical Information of China (English)

    乌兰辉; 吴松; 卢建勋; 杨慧; 杨庆云

    2012-01-01

    Objective;To establish an HPLC method to separate citalopram enantiomers on ovomucoid chiral column for optical purity detection of escitalopram oxalate. Methods-. The mobile phase was recommended as acetoni-trile-0. 05 mol · L-1 phosphate buffer(pH 7. 0) ( 15.'85)at a flow rate of 1.0 mL · min-1.The column temperature was 30℃ and the detection wavelength was 240 nm. Results; Citalopram enantiomers were separated under the above conditions, the resolution between S - and R - citalopram was 1. 90. The optical purity of escitalopram oxalate was more than 97. 9%. Conclusion; With good resolution and repeatability, the method can be reliably used for chiral separation of citalopram enantiomers, and determination of the optical purity of S - and R - citalopram sample.%目的:建立西酞普兰对映异构体的HPLC手性分析方法,用于草酸艾司西酞普兰光学纯度的分析测定.方法:采用不易变性的卵类粘蛋白键合硅胶(ES - OVM)为手性固定相,以乙腈-0.05 mol·L-1磷酸盐缓冲液(pH 7.0)(15∶85)为流动相,流速为1.0 mL·min-1,柱温30℃,检测波长240nm,对西酞普兰对映异构体进行分离测定.结果:西酞普兰对映异构体在卵粘蛋白柱上实现了良好的分离,分离度为1.90.将该方法应用于手性拆分得到的草酸艾司西酞普兰的光学纯度测定,结果光学纯度大于97.9%.结论:该方法分离度与重现性好,可用于西酞普兰的光学纯度的分析测定及对拆分过程进行监测,结果可靠.

  3. One-Pot Catalysis Using a Chiral Iridium Complex/Brønsted Base: Catalytic Asymmetric Synthesis of Catalponol.

    Science.gov (United States)

    Suzuki, Takeyuki; Ismiyarto; Ishizaka, Yuka; Zhou, Da-Yang; Asano, Kaori; Sasai, Hiroaki

    2015-11-01

    Tandem asymmetric hydrogen transfer oxidation/aldol condensation under relay catalysis of a chiral iridium complex/achiral Brønsted base binary system is described for the synthesis of α-benzylidene-γ-hydroxytetralones with high ee's. A two-step synthesis of catalponol was achieved using this sequential methodology together with regio- and stereoselective hydroboration. PMID:26496409

  4. Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase%运用手性固定相研究外消旋布洛芬的光学分离

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ibuprofen is widely used as a non-steroidal anti-inflammatory drug and produced as racemic mixture. Its pharmacological activity resides only in S-(+)-enantiomer, and R-(-)-enantiomer is not only inactive but also has many side effects. Thus it is necessary to separate Renanfiomer from racemic ibuprofen. We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography (HPLC). Out of three different chiral stationary phases, which were selected on the basis of structure and availability, two were found to be effective. There was optimum eluent composition for each stationary phase for good resolution in optical separation. Resolution decreased with increase of eluent flow rate, but effect of injection volume on resolution was insignificant at high eluent flow rate.

  5. 羟丙基-β-环糊精为手性选择剂分离6种手性药物%Enantiomeric separation of six chiral drugs with hydroxypropyl-β-cyclodextrin as a chiral selector

    Institute of Scientific and Technical Information of China (English)

    赵旻; 张欣娜; 姜珍; 崔艳; 郭兴杰

    2013-01-01

    Objective To separate the enantiomers of six drugs by capillary electrophoresis with hydroxyprop-yl-β-cyclodextrin(HP-β-CD)as a chiral selector. Methods The separation of the enantiomers was performed in an untreated fused-silica capillary tube,in the buffer of NaH2PO4 with the voltage of 20 kV. The influences of buffer pH, HP-β-CD concentration, buffer concentration on separation were investigated. Results Under the optimal conditions, the resolutions of tropicamide, amlodipine, nicardipine, terbutaline, tramadol hydrochloride and phenoxybenzamine hydrochloride were 2. 6, 3. 7,1.3,4. 1, 2. 5 and 1.8, respectively. Conclusions The method is effective for enantioseparation of tropicamide, amlodipine, terbutaline, tramadol hydrochloride and phenoxybenzamine hydrochloride.%目的 以羟丙基-β环糊精(HP-β-CD)为手性选择剂,利用毛细管电泳法分离6种药物对映体.方法 采用未涂层熔融石英毛细管柱,磷酸二氢钠缓冲溶液,分离电压20 kV,考察了背景电解质pH值、环糊精浓度、缓冲盐浓度对对映体分离的影响.结果 在最优的电泳条件下,托吡卡胺、氨氯地平、尼卡地平、特布他林、盐酸曲马多和盐酸酚苄明的分离度分别为2.6、3.7、1.3、4.1、2.5和1.8.结论 所建立的方法适于托吡卡胺、氨氯地平、特布他林、盐酸曲马多和盐酸酚苄明的对映体分离.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  7. Chiral metamaterials with negative refractive index based on four "U" split ring resonators

    OpenAIRE

    Li, Zhaofeng; Zhao, Rongkuo; Koschny, Thomas; Kafesaki, Maria; Alici, Kamil Boratay; Colak, Evrim; Caglayan, Humeyra; Soukoulis, Ekmel Ozbayand C. M.

    2010-01-01

    A uniaxial chiral metamaterial is constructed by double-layered four "U" split ring resonators mutually twisted by 90 degrees. It shows a giant optical activity and circular dichroism. The retrieval results reveal that a negative refractive index is realized for circularly polarized waves due to the large chirality. The experimental results are in good agreement with the numerical results.

  8. Broadband angle- and permittivity-insensitive nondispersive optical activity based on chiral metamaterials

    CERN Document Server

    Song, Kun; Su, Zhaoxian; Ding, Changlin; Liu, Yahong; Luo, Chunrong; Zhao, Xiaopeng; Bhattarai, Khagendra; Zhou, Jiangfeng

    2016-01-01

    Because of the strong inherent resonances, the giant optical activity obtained via chiral metamaterials generally suffers from high dispersion, which has been a big stumbling block to broadband applications. In this paper, we propose a type of chiral metamaterial consisting of interconnected metal helix structures with four-fold symmetry, which exhibits nonresonant Drude-like response and can therefore avoid the highly dispersive optical activity resulting from resonances. It shows that the well-designed chiral metamaterial can achieve nondispersive and pure optical activity with high transmittance in a broadband frequency range. And the optical activity of multi-layer chiral metamaterials is proportional to the layer numbers of single-layer chiral metamaterial. Most remarkably, the broadband behaviors of nondispersive optical activity and high transmission are insensitive to the incident angles of electromagnetic waves and permittivity of dielectric substrate, thereby enabling more flexibility in polarizatio...

  9. Chiral Electronics

    OpenAIRE

    Kharzeev, Dmitri E.; Yee, Ho-Ung

    2012-01-01

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

  10. Chiral photochemistry

    CERN Document Server

    Inoue, Yoshihisa

    2004-01-01

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

  11. Bringing chiral optical forces to dominance with optical nanofibers

    CERN Document Server

    Alizadeh, M H

    2016-01-01

    Transverse spin angular momentum (SAM) of light and associated transverse chiral optical forces have received tremendous attention recently as the latter may lead to an optical separation of chiral biomolecules. Previous schemes to generate chiral forces are plagued by the fact that the chiral optical forces are orders of magnitude smaller than conventional gradient and scattering forces. The relative magnitude of chiral and non-chiral forces represents a fundamental challenge for the implementation of chiral separation schemes. In this work we demonstrate that, by spatially separating the maxima of transverse spin density from the gradient of field intensity, in the vicinity of optical nanofibers and nanowires, chiral optical forces can emerge that are stronger than gradient and scattering forces. This finding has important implications for the design of improved optical separation schemes for chiral biomolecules.

  12. 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.

  13. Development of a Validated LC Method for Separation of Process-Related Impurities Including the R-Enantiomer of S-Pramipexole on Polysaccharide Chiral Stationary Phases.

    Science.gov (United States)

    Ramisetti, Nageswara Rao; Kuntamukkala, Ramakrishna; Arnipalli, Manikanta Swamy

    2015-07-01

    Despite the availability of a few methods for individual separation of S-pramipexole from its process-related impurities, no common liquid chromatography (LC) method is reported so far in the literature. The present article describes the development of a single-run LC method for simultaneous determination of S-pramipexole and its enantiomeric and process-related impurities on a Chiralpak AD-H (150 x 4.6 mm, 5μm) column using n-hexane/ethanol/n-butylamine (75:25:0.1 v/v/v) as a mobile phase in an isocratic mode of elution at a flow rate of 1.2 ml/min at 30°C. The chromatographic eluents were monitored at a wavelength of 260 nm using a photodiode array detector. Excellent enantioseparation with good resolutions (Rs ≥ 2.88) and peak shapes (As ≤ 1.21) for all analytes was achieved. The proposed method was validated according to International Conference Harmonization (ICH) guidelines in terms of accuracy, precision, sensitivity, and linearity. Limits of quantification of impurities (0.25-0.55 μg/ml) indicate the highest sensitivity achievable by the proposed method. The method has an advantage of selectivity and suitability for routine determination of not only chiral impurity but also all possible related substances in active pharmaceutical ingredients of S-pramipexole.

  14. Synthesis, X-ray, and Spectroscopic Study of Dissymmetric Tetrahedral Zinc(II) Complexes from Chiral Schiff Base Naphthaldiminate Ligands with Apparent Exception to the ECD Exciton Chirality.

    Science.gov (United States)

    Enamullah, Mohammed; Makhloufi, Gamall; Ahmed, Rifat; Joy, Baitul Alif; Islam, Mohammad Ariful; Padula, Daniele; Hunter, Howard; Pescitelli, Gennaro; Janiak, Christoph

    2016-07-01

    Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminate (R- or S-N^O), diastereoselectively provide Λ- or Δ-chiral-at-metal four-coordinated Zn(R- or S-N^O)2 {Ar = C6H5; Zn-1R or Zn-1S and p-C6H4OMe; Zn-2R or Zn-2S}. Two R- or S-N^O-chelate ligands coordinate to the zinc(II) in a tetrahedral mode and induce Λ- or Δ-configuration at the zinc metal center. In the solid state, the R- or S-ligand diastereoselectively gives Λ- or Δ-Zn configuration, respectively, and forms enantiopure crystals. Single crystal structure determinations show two symmetry-independent molecules (A and B) in each asymmetric unit to give Z' = 2 structures. Electronic circular dichroism (ECD) spectra show the expected mirror image relationship resulting from diastereomeric excess toward the Λ-Zn for R-ligands and Δ-Zn for S-ligands in solution. ECD spectra are well reproduced by TDDFT calculations, while the application of the exciton chirality method, in the common point-dipole approximation, predicts the wrong sign for the long-wavelength couplet. A dynamic diastereomeric equilibrium (Λ vs Δ) prevails for both R- and S-ligand-metal complexes in solution, respectively, evidenced by (1)H NMR spectroscopy. Variable temperature (1)H NMR spectra show a temperature-dependent shift of the diastereomeric equilibrium and confirm Δ-Zn configuration (for S-ligand) to be the most stable one and favored at low temperature. DSC analyses provide quantitative diastereomeric excess in the solid state for Zn-2R and Zn-2S, which is comparable to the results of solution studies.

  15. Synthesis, X-ray, and Spectroscopic Study of Dissymmetric Tetrahedral Zinc(II) Complexes from Chiral Schiff Base Naphthaldiminate Ligands with Apparent Exception to the ECD Exciton Chirality.

    Science.gov (United States)

    Enamullah, Mohammed; Makhloufi, Gamall; Ahmed, Rifat; Joy, Baitul Alif; Islam, Mohammad Ariful; Padula, Daniele; Hunter, Howard; Pescitelli, Gennaro; Janiak, Christoph

    2016-07-01

    Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminate (R- or S-N^O), diastereoselectively provide Λ- or Δ-chiral-at-metal four-coordinated Zn(R- or S-N^O)2 {Ar = C6H5; Zn-1R or Zn-1S and p-C6H4OMe; Zn-2R or Zn-2S}. Two R- or S-N^O-chelate ligands coordinate to the zinc(II) in a tetrahedral mode and induce Λ- or Δ-configuration at the zinc metal center. In the solid state, the R- or S-ligand diastereoselectively gives Λ- or Δ-Zn configuration, respectively, and forms enantiopure crystals. Single crystal structure determinations show two symmetry-independent molecules (A and B) in each asymmetric unit to give Z' = 2 structures. Electronic circular dichroism (ECD) spectra show the expected mirror image relationship resulting from diastereomeric excess toward the Λ-Zn for R-ligands and Δ-Zn for S-ligands in solution. ECD spectra are well reproduced by TDDFT calculations, while the application of the exciton chirality method, in the common point-dipole approximation, predicts the wrong sign for the long-wavelength couplet. A dynamic diastereomeric equilibrium (Λ vs Δ) prevails for both R- and S-ligand-metal complexes in solution, respectively, evidenced by (1)H NMR spectroscopy. Variable temperature (1)H NMR spectra show a temperature-dependent shift of the diastereomeric equilibrium and confirm Δ-Zn configuration (for S-ligand) to be the most stable one and favored at low temperature. DSC analyses provide quantitative diastereomeric excess in the solid state for Zn-2R and Zn-2S, which is comparable to the results of solution studies. PMID:27295327

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

    CERN Document Server

    Kharzeev, Dmitri; Meyer, Rene

    2016-01-01

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

  17. Temperature-induced inversion of elution order in the chromatographic enantioseparation of 1,1'-bi-2-naphthol on an immobilized polysaccharide-based chiral stationary phase.

    Science.gov (United States)

    Yao, Bixia; Zhan, Fengping; Yu, Guangyan; Chen, Zhifen; Fan, Wenjing; Zeng, Xiongping; Zeng, Qingle; Weng, Wen

    2009-07-10

    In this work, the enantioseparations of 1,1'-bi-2-naphthol (BINOL) and its three derivatives were performed on an immobilized polysaccharide-based chiral stationary phase, Chiralpak IA, under normal-phase mode. The effects of the content of polar modifier in the mobile phase and the column temperature on the retention and enantioseparation were investigated in detail. Temperature-induced inversion of elution order for BINOL was observed directly when n-hexane/2-propanol (92/8, v/v) was used as mobile phase. The isoenantioselective temperature (T(iso)) was calculated to be 31.4 degrees C. When n-hexane/2-propanol/THF (93/2/5, v/v/v) was used as mobile phase, the T(iso) value decreased to -8.2 degrees C. Entropically driven enantioseparation which had practical application was obtained successfully (separation factor being 1.189 and 1.332 at 25 degrees C and 50 degrees C, respectively). The corresponding thermodynamic parameters for other three binaphthyl compounds were compared with that for BINOL. Some inferences about chiral recognition mechanism were stressed.

  18. The synthesis and characterization of novel brush-type chiral stationary phase based on terpenoid selector for resolution of chiral drugs

    OpenAIRE

    Wang Dao-Cai; Luo Jia; Yao Shun; Song Hang

    2016-01-01

    In the light of the chiral resolution mechanism and structures of brush-type CSP, a new chiral selector 4′-carboxyl-1′-ursolic methyl ester-3β-yl-benzoate has been prepared. Then the terpenoid chiral selector was covalently linked to 3-aminopropyl silica gel. Its structure identification data are provided by 1H NMR, MS and elementary analysis. The enantiodiscriminating capability of the brush-type CSP was evaluated by static adsorption experiment with methyl mandelate, aniline derivative of m...

  19. Ligand-based reactivity of a platinum bisdithiolene: double diene addition yields a new C2-chiral chelate ligand.

    Science.gov (United States)

    Kerr, Mitchell J; Harrison, Daniel J; Lough, Alan J; Fekl, Ulrich

    2009-10-01

    The reaction of Pt(tfd)(2) [tfd = S(2)C(2)(CF(3))(2)] with excess 2,3-dimethyl-1,3-butadiene initially yields the expected 1:1 adduct, in which the diene has added across two sulfur atoms on separate tfd ligands. However, within 1 day at 50 degrees C, this kinetic product quantitatively converts into a thermodynamic product where two dienes have added to one tfd ligand via unprecedented addition across the dithiolene CS bonds. The new reaction is highly selective for the C(2)-symmetric diastereomer. A new chiral bisthioether chelate ligand has formed in the product, which has been characterized crystallographically. PMID:19634863

  20. 新型高效液相色谱流动相手性添加剂法拆分头孢氨苄对映体%Separation of Cefalexin Enantiomers by a New Chiral HPLC Mobile Phase Additives

    Institute of Scientific and Technical Information of China (English)

    沈静茹; 王伟; 余学红; 蔡薇; 张祎; 刘武林

    2013-01-01

      用双[-6-氧-(3-脱氧柠檬酸单酯-4)]-β-环糊精为手性流动相添加剂,以有机弱酸的形式和三乙胺组成缓冲体系,在高效液相色谱(HPLC)中实现了头孢氨苄对映体的手性拆分.结合碳18硅胶键合(ODS-BP)柱为固定相,该缓冲液与不同比例乙腈混合形成流动相,考察了流动相配比、pH值、手性流动相添加剂浓度等因素对头孢氨苄2对对映体手性分离的影响.结果表明:在pH 8.8,流速0.6 mL/min,检测波长310 nm,添加剂浓度为5.0 mmol/L缓冲液的最佳条件下,可实现头孢氨苄4个对映异构体色谱峰的基线分离,最佳条件下4峰中相邻两峰分离度Rs 分别为3.41、5.34和8.93.%Using bis-[6-oxygen-(3-deoxycitric acid monoester-4)]-β-cyclodextrin as the chiral HPLC mobile phase additive, an organic weak acid(β-cyclodextrin derivative) and triethylamine as buffer system, enantioseparation of cefalexin enantiomers was achieved. Based on an ODS-BP column stationary phase and a mixed mobile phase of acetonitrile and the additive-triethylamine buffer, the effects of the ratio of mobile phase, pH value and the concentration of the chiral additive concentration on the separation of cephalexin 2 enantiomers were discussed. The results showed that under the optimum conditions:pH8. 8, 0. 6mL/min flow rate, ultraviolet detection wavelength of 310 nm, additive concentration of 5. 0 mmol/L, baseline separation of 4 peaks of cefalexin enantiomers could be obtained, with the Rs of adjacent peaks being 3. 41, 5. 34 and 8. 93,respectively.

  1. Towards the chiral metabolomics: Liquid chromatography-mass spectrometry based DL-amino acid analysis after labeling with a new chiral reagent, (S)-2,5-dioxopyrrolidin-1-yl-1-(4,6-dimethoxy-1,3,5-triazin-2-yl)pyrrolidine-2-carboxylate, and the application to saliva of healthy volunteers.

    Science.gov (United States)

    Mochizuki, Toshiki; Takayama, Takahiro; Todoroki, Kenichiro; Inoue, Koichi; Min, Jun Zhe; Toyo'oka, Toshimasa

    2015-05-22

    A novel triazine-type chiral derivatization reagent, i.e., (S)-2,5-dioxopyrrolidin-1-yl-1-(4,6-dimethoxy-1,3,5-triazin-2-yl) pyrrolidine-2-carboxylate (DMT-(S)-Pro-OSu), was developed for the highly sensitive and selective detection of chiral amines and amino acids by UPLC-MS/MS analysis. The enantiomers of amino acids were easily labeled with the reagents at room temperature within 40 min in an alkaline medium containing triethylamine. The diastereomers derived from proteolytic amino acids, except serine, were well separated under isocratic elution conditions by reversed-phase chromatography using an ODS column (Rs=1.2-9.0). DL-Serine was separated by use of an ADME column which has relatively higher polar surface than the conventional ODS column. The characteristic product ions, i.e., m/z 195.3 and m/z 209.3, were detected from all the diastereomers by the collision-induced dissociation of the protonated molecule. A highly sensitive detection on the amol-fmol level was obtained from the selected reaction monitoring (SRM) chromatogram. The chiral amines (e.g., adrenaline and noradrenaline) labeled with DMT-(S)-Pro-OSu were also well separated and sensitively detected by the present procedure. The method using DMT-(S)-Pro-OSu was used for the determination of DL-amino acids in the human saliva from healthy volunteers. Various L-amino acids were identified in the saliva. Furthermore, D-alanine (D-Ala) and D-proline (D-Pro) were also detected in relatively high concentrations (>5%). The ratio was higher in male saliva than in female saliva. However, the difference in the ratio of D-Ala for one day was not very high and the effect of foods and beverage seemed to be negligible. Based on the results using L-Ala-d3, the D-Ala in saliva seemed to be produced due to the racemization with some enzymes such as racemase. The racemization reaction was reversible, i.e., D-Ala-d3 was also racemized to L-Ala-d3 in saliva. Thus, care should be taken during the analysis of DL

  2. The quest for chirality

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-07-01

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

  3. Blind image separation based on exponentiated transmuted Weibull distribution

    OpenAIRE

    Adam, A. M.; Farouk, R. M.; El-aziz, M. E. Abd

    2016-01-01

    In recent years the processing of blind image separation has been investigated. As a result, a number of feature extraction algorithms for direct application of such image structures have been developed. For example, separation of mixed fingerprints found in any crime scene, in which a mixture of two or more fingerprints may be obtained, for identification, we have to separate them. In this paper, we have proposed a new technique for separating a multiple mixed images based on exponentiated t...

  4. Chiral separation of sibutramine hydrochloride enantiomers by capillary electrophoresis%盐酸西布曲明对映体的毛细管电泳手性拆分

    Institute of Scientific and Technical Information of China (English)

    黄碧云; 赵鑫; 袁牧

    2011-01-01

    Objective: To separate Sibutramine Hydrochloride, a chiral drug, by capillary zone electrophoresis using sulfated β-cyclodextrin (S-β-CD) as the selector. Methods: The impacts of pH value of background electrolyte, levels of S-β-CD, buffer concentrations and applied voltage on the chiral separation were investigated. Results:Optimal chiral separation of Sibutramine Hydrochloride was achieve with 5% S-β-CD in a background electrolyte system containing 15 mmol/L phosphate acid adjusted to pH4. 0 with triethanolamine (H3PO4-TEA) ,a voltage of 30 kV,a temperature at 16℃, and a detection wavelength at 223 nm (degree of chiral separation: 5.6). Conclusion; The method used for chiral separation of Sibutramine Hydrochloride in this study appears quick,easy to use and favorably accurate.%目的:以磺化-β-环糊精(S-β-CD)作为手性选择剂,用毛细管区带电泳法对手性药物盐酸西布曲明进行了拆分研究.方法:考察了背景电解质溶液的pH值、S-β-CD的浓度、缓冲液浓度及电压等对分离的影响.结果:在背景电解质为含5%S -β-CD的15 mmol/L磷酸-三乙醇胺(H3 P04-TEA)(pH 4.0)体系,电压30 kV,温度为16℃,检测波长为223 nm条件下,盐酸西布曲明可以得到良好分离,分离度为5.6.结论:该方法可用于盐酸西布曲明的拆分,具有快速、便捷、准确性好等优点.

  5. An electrochemical sensor based on cellulose nanocrystal for the enantioselective discrimination of chiral amino acids.

    Science.gov (United States)

    Bi, Qing; Dong, Shuqing; Sun, Yaming; Lu, Xiaoquan; Zhao, Liang

    2016-09-01

    A novel electrochemical sensor based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanocrystals (TOCNCs) and l-cystines (l-Cys) modified Au electrode (TOCNC/l-Cys/Au) has been fabricated for detection and discrimination of the enantiomers of phenylalanine (Phe), leucine (Leu), and valine (Val). The three amino acids are in connection with metabolism diseases. The TOCNC/l-Cys/Au electrode exhibited obvious peak current difference for the amino acid enantiomers by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The TOCNCs on the electrode surface expressed different interactions with d- and l-amino acids, so the electrochemical recognitions of the three amino acid enantiomers were achieved. TOCNCs were characterized by Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). The modified electrodes were characterized by SEM and electrochemical techniques. According to DPV, peak currents of the two enantiomers decreased linearly with their concentrations. Furthermore, satisfactory results were obtained when this electrode was applied to measure the d- and l-Phe mixture. The experimental results show that TOCNCs are suitable material for chiral sensor. The contrast of serum sample of healthy people and patients with type 2 diabetes also was proposed, and significant difference was exhibited on the modified electrode. This work is significant for the screening, diagnosis, and treatment of multiple metabolic diseases. PMID:27288559

  6. Optimal separable bases and molecular collisions

    International Nuclear Information System (INIS)

    A new methodology is proposed for the efficient determination of Green's functions and eigenstates for quantum systems of two or more dimensions. For a given Hamiltonian, the best possible separable approximation is obtained from the set of all Hilbert space operators. It is shown that this determination itself, as well as the solution of the resultant approximation, are problems of reduced dimensionality for most systems of physical interest. Moreover, the approximate eigenstates constitute the optimal separable basis, in the sense of self-consistent field theory. These distorted waves give rise to a Born series with optimized convergence properties. Analytical results are presented for an application of the method to the two-dimensional shifted harmonic oscillator system. The primary interest however, is quantum reactive scattering in molecular systems. For numerical calculations, the use of distorted waves corresponds to numerical preconditioning. The new methodology therefore gives rise to an optimized preconditioning scheme for the efficient calculation of reactive and inelastic scattering amplitudes, especially at intermediate energies. This scheme is particularly suited to discrete variable representations (DVR's) and iterative sparse matrix methods commonly employed in such calculations. State to state and cumulative reactive scattering results obtained via the optimized preconditioner are presented for the two-dimensional collinear H + H2 → H2 + H system. Computational time and memory requirements for this system are drastically reduced in comparison with other methods, and results are obtained for previously prohibitive energy regimes

  7. Optimal separable bases and molecular collisions

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, L W [Univ. of California, Berkeley, CA (United States)

    1997-12-01

    A new methodology is proposed for the efficient determination of Green`s functions and eigenstates for quantum systems of two or more dimensions. For a given Hamiltonian, the best possible separable approximation is obtained from the set of all Hilbert space operators. It is shown that this determination itself, as well as the solution of the resultant approximation, are problems of reduced dimensionality for most systems of physical interest. Moreover, the approximate eigenstates constitute the optimal separable basis, in the sense of self-consistent field theory. These distorted waves give rise to a Born series with optimized convergence properties. Analytical results are presented for an application of the method to the two-dimensional shifted harmonic oscillator system. The primary interest however, is quantum reactive scattering in molecular systems. For numerical calculations, the use of distorted waves corresponds to numerical preconditioning. The new methodology therefore gives rise to an optimized preconditioning scheme for the efficient calculation of reactive and inelastic scattering amplitudes, especially at intermediate energies. This scheme is particularly suited to discrete variable representations (DVR`s) and iterative sparse matrix methods commonly employed in such calculations. State to state and cumulative reactive scattering results obtained via the optimized preconditioner are presented for the two-dimensional collinear H + H{sub 2} {yields} H{sub 2} + H system. Computational time and memory requirements for this system are drastically reduced in comparison with other methods, and results are obtained for previously prohibitive energy regimes.

  8. Control of Metal Arrays Based on Heterometallics Masquerading in Heterochiral Aggregations of Chiral Clothespin-Shaped Complexes.

    Science.gov (United States)

    Naito, Masaya; Inoue, Ryo; Iida, Masayuki; Kuwajima, Yuuki; Kawamorita, Soichiro; Komiya, Naruyoshi; Naota, Takeshi

    2015-09-01

    Heterometal arrays in molecular aggregations were obtained by the spontaneous and ultrasound-induced gelation of organic liquids containing the chiral, clothespin-shaped trans-bis(salicylaldiminato) d8 transition-metal complexes 1. Heterometallic mixtures of complexes 1 a (Pd) and 1 b (Pt) underwent strict heterochiral aggregation entirely due to the organic shell structure of the clothespin shape, with no effect of the metal cores. This phenomenon provides an unprecedented means of generating highly controlled heterometallic arrangements such as alternating sequences [(+)-Pd(-)-Pt(+)-Pd(-)-Pt⋅⋅⋅] as well as a variety of single metal-enriched arrays (e.g., [(+)-Pt(-)-Pd(+)-Pd(-)-Pd(+)-Pd(-)-Pd⋅⋅⋅] and [(+)-Pd(-)-Pt(+)-Pt(-)-Pt(+)-Pt(-)-Pt⋅⋅⋅]) upon the introduction of an optically active masquerading unit with a different metal core in the heterochiral single-metal sequence. The present method can be applied to form various new aggregates with optically active Pd and Pt units, to allow 1) tuning of the gelation ultrasound sensitivity based on the different hearing abilities of the metal units; 2) aggregation-induced chirality transfer between heterometallic species; and 3) aggregation-induced chirality enhancement. A mechanistic rationale is proposed for these molecular aggregations based on the molecular structures of the units and the morphologies of the aggregates. PMID:26212577

  9. 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.

  10. Chiral Superconductors

    OpenAIRE

    Kallin, Catherine; Berlinsky, John

    2015-01-01

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

  11. Dynamic Chirality in Nuclei

    International Nuclear Information System (INIS)

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

  12. Non-reciprocal few-photon devices based on chiral waveguide-emitter couplings

    CERN Document Server

    Gonzalez-Ballestero, C; Vidal, F J Garcia; Gonzalez-Tudela, A

    2016-01-01

    We demonstrate the possibility of designing efficient, non reciprocal few-photon devices by exploiting the chiral coupling between two waveguide modes and a single quantum emitter. We show how this system can induce non-reciprocal photon transport at the single-photon level and act as an optical diode. Afterwards, we also show how the same system shows a transistor-like behaviour for a two-photon input. The efficiency in both cases is shown to be large for feasible experimental implementations. Our results illustrate the potential of chiral waveguide-emitter couplings for applications in quantum circuitry.

  13. Chiral Nanozymes-Gold Nanoparticle-Based Transphosphorylation Catalysts Capable of Enantiomeric Discrimination.

    Science.gov (United States)

    Chen, Jack L-Y; Pezzato, Cristian; Scrimin, Paolo; Prins, Leonard J

    2016-05-17

    Enantioselectivity in RNA cleavage by a synthetic metalloenzyme has been demonstrated for the first time. Thiols containing chiral Zn(II) -binding head groups have been self-assembled on the surface of gold nanoparticles. This results in the spontaneous formation of chiral bimetallic catalytic sites that display different activities (kcat ) towards the enantiomers of an RNA model substrate. Substrate selectivity is observed when the nanozyme is applied to the cleavage of the dinucleotides UpU, GpG, ApA, and CpC, and remarkable differences in reactivity are observed for the cleavage of the enantiomerically pure dinucleotide UpU. PMID:26919202

  14. Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction

    Directory of Open Access Journals (Sweden)

    Marina Rubina

    2014-07-01

    Full Text Available A novel class of chiral phosphanyl-oxazoline (PHOX ligands with a conformationally rigid cyclopropyl backbone was synthesized and tested in the intermolecular asymmetric Heck reaction. Mechanistic modelling and crystallographic studies were used to predict the optimal ligand structure and helped to design a very efficient and highly selective catalytic system. Employment of the optimized ligands in the asymmetric arylation of cyclic olefins allowed for achieving high enantioselectivities and significantly suppressing product isomerization. Factors affecting the selectivity and the rate of the isomerization were identified. It was shown that the nature of this isomerization is different from that demonstrated previously using chiral diphosphine ligands.

  15. Mass-Selective Chiral Analysis.

    Science.gov (United States)

    Boesl, Ulrich; Kartouzian, Aras

    2016-06-12

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

  16. Mass-Selective Chiral Analysis

    Science.gov (United States)

    Boesl, Ulrich; Kartouzian, Aras

    2016-06-01

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

  17. 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. PMID:21384440

  18. Anomalous Maxwell equations for inhomogeneous chiral plasma

    CERN Document Server

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

    2016-01-01

    Using the chiral kinetic theory we derive the electric and chiral current densities in inhomogeneous relativistic plasma. We also derive equations for the electric and chiral charge chemical potentials that close the Maxwell equations in such a plasma. The analysis is done in the regimes with and without a drift of the plasma as a whole. In addition to the currents present in the homogeneous plasma (Hall current, chiral magnetic, chiral separation, and chiral electric separation effects, as well as Ohm's current) we derive several new terms associated with inhomogeneities of the plasma. Apart from various diffusion-like terms, we find also new dissipation-less terms that are independent of relaxation time. Their origin can be traced to the Berry curvature modifications of the kinetic theory.

  19. Anomalous Maxwell equations for inhomogeneous chiral plasma

    Science.gov (United States)

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

    2016-05-01

    Using the chiral kinetic theory we derive the electric and chiral current densities in inhomogeneous relativistic plasma. We also derive equations for the electric and chiral chemical potentials that close the Maxwell equations in such a plasma. The analysis is done in the regimes with and without a drift of the plasma as a whole. In addition to the currents present in the homogeneous plasma (Hall current, chiral magnetic, chiral separation, and chiral electric separation effects, as well as Ohm's current) we derive several new terms associated with inhomogeneities of the plasma. Apart from various diffusionlike terms, we find also new dissipationless terms that are independent of relaxation time. Their origin can be traced to the Berry curvature modifications of the kinetic theory.

  20. A general model for membrane-based separation processes

    DEFF Research Database (Denmark)

    Soni, Vipasha; Abildskov, Jens; Jonsson, Gunnar Eigil;

    2009-01-01

    A separation process could be defined as a process that transforms a given mixture of chemicals into two or more compositionally distinct end-use products. One way to design these separation processes is to employ a model-based approach, where mathematical models that reliably predict the process...... behaviour will play an important role. In this paper, modelling of membrane-based processes for separation of gas and liquid mixtures are considered. Two general models, one for membrane-based liquid separation processes (with phase change) and another for membrane-based gas separation are presented. The...... modelling assumptions. Analyses of the generated models, together with their validation and application in process design/analysis are highlighted through several case studies....

  1. Conceptual design of distillation-based hybrid separation processes.

    Science.gov (United States)

    Skiborowski, Mirko; Harwardt, Andreas; Marquardt, Wolfgang

    2013-01-01

    Hybrid separation processes combine different separation principles and constitute a promising design option for the separation of complex mixtures. Particularly, the integration of distillation with other unit operations can significantly improve the separation of close-boiling or azeotropic mixtures. Although the design of single-unit operations is well understood and supported by computational methods, the optimal design of flowsheets of hybrid separation processes is still a challenging task. The large number of operational and design degrees of freedom requires a systematic and optimization-based design approach. To this end, a structured approach, the so-called process synthesis framework, is proposed. This article reviews available computational methods for the conceptual design of distillation-based hybrid processes for the separation of liquid mixtures. Open problems are identified that must be addressed to finally establish a structured process synthesis framework for such processes.

  2. Quinine-Based Zwitterionic Chiral Stationary Phase as a Complementary Tool for Peptide Analysis: Mobile Phase Effects on Enantio- and Stereoselectivity of Underivatized Oligopeptides.

    Science.gov (United States)

    Ianni, Federica; Sardella, Roccaldo; Carotti, Andrea; Natalini, Benedetto; Lindner, Wolfgang; Lämmerhofer, Michael

    2016-01-01

    Peptide stereoisomer analysis is of importance for quality control of therapeutic peptides, the analysis of stereochemical integrity of bioactive peptides in food, and the elucidation of the stereochemistry of peptides from a natural chiral pool which often contains one or more D-amino acid residues. In this work, a series of model peptide stereoisomers (enantiomers and diastereomers) were analyzed on a zwitterionic ion-exchanger chiral stationary phase (Chiralpak ZWIX(+) 5 µm), in order to investigate the retention and separation performance for such compounds on this chiral stationary phase and elucidate its utility for this purpose. The goal of the study focused on 1) investigations of the effects of the sample matrix used to dissolve the peptide samples; 2) optimization of the mobile phase (enabling deriving information on factors of relevance for retention and separation); and 3) derivation of structure-selectivity relationships. It turned out that small di- and tripeptides can be well resolved under optimized conditions, typically with resolutions larger than 1.5. The optimized mobile phase often consisted of methanol-tetrahydrofuran-water (49:49:2; v/v/v) with 25 mM formic acid and 12.5 mM diethylamine. This work proposes some guidance on which mobile phases can be most efficiently used for peptide stereoisomer separations on Chiralpak ZWIX. Chirality 28:5-16, 2016. © 2015 Wiley Periodicals, Inc.

  3. Calixarene based chiral solvating agents for α-hydroxy carboxylic acids

    Science.gov (United States)

    Bozkurt, Selahattin

    2013-09-01

    Novel chiral calix[4]arene derivatives functionalized at the lower rim have been prepared from the reaction of p-tert-butylcalix[4]arene diamine derivative with N-Phthaloyl-L-phenylalanine or (2S)-2-((benzyloxy)carbonyl)amino)-3-hydroxypropanoic acid or (2S,3R)-2-((benzyloxy)carbonyl)amino-3-hydroxybutanoic acid in 63-81% yield. The structures of these receptors were characterized by FTIR, 1H, 13C and 2D COSY NMR spectroscopy. The enantioselective recognition of these receptors towards the enantiomers of racemic carboxylic acids was studied by 1H NMR spectroscopy. The molar ratios of the chiral compounds with each of the enantiomers of guests were determined by using Job plots. The Job plots indicate that the hosts form 1:2 instantaneous complexes with all guests. The receptors exhibited different chiral recognition abilities toward the enantiomers of racemic guests. NMR studies demonstrated that the receptors function as highly effective chiral shift reagents for determining the enantiomeric purity of a series of carboxylic acids.

  4. Chiral shift reagent for amino acids based on resonance-assisted hydrogen bonding.

    Science.gov (United States)

    Chin, Jik; Kim, Dong Chan; Kim, Hae-Jo; Panosyan, Francis B; Kim, Kwan Mook

    2004-07-22

    [structure: see text] A chiral aldehyde that forms resonance-assisted hydrogen bonded imines with amino acids has been developed. This hydrogen bond not only increases the equilibrium constant for imine formation but also provides a highly downfield-shifted NMR singlet for evaluating enantiomeric excess and absolute stereochemistry of amino acids. PMID:15255698

  5. Amino acids as chiral anionic ligands for ruthenium based asymmetric olefin metathesis.

    Science.gov (United States)

    Ivry, Elisa; Ben-Asuly, Amos; Goldberg, Israel; Lemcoff, N Gabriel

    2015-03-01

    Several amino acid ligands were introduced into the Hoveyda-Grubbs 2nd generation complex by a facile anionic ligand exchange. The chiral pre-catalysts obtained displayed enantioselectivity in asymmetric ring-closing and ring-opening cross-metathesis reactions. Reduction of the lability of the carboxylate ligands was found to be cardinal for improving the observed enantiomeric product enrichment.

  6. Amino acids as chiral anionic ligands for ruthenium based asymmetric olefin metathesis.

    Science.gov (United States)

    Ivry, Elisa; Ben-Asuly, Amos; Goldberg, Israel; Lemcoff, N Gabriel

    2015-03-01

    Several amino acid ligands were introduced into the Hoveyda-Grubbs 2nd generation complex by a facile anionic ligand exchange. The chiral pre-catalysts obtained displayed enantioselectivity in asymmetric ring-closing and ring-opening cross-metathesis reactions. Reduction of the lability of the carboxylate ligands was found to be cardinal for improving the observed enantiomeric product enrichment. PMID:25656548

  7. Robust, chiral, and porous BINAP-based metal-organic frameworks for highly enantioselective cyclization reactions.

    Science.gov (United States)

    Sawano, Takahiro; Thacker, Nathan C; Lin, Zekai; McIsaac, Alexandra R; Lin, Wenbin

    2015-09-30

    We report here the design of BINAP-based metal-organic frameworks and their postsynthetic metalation with Rh complexes to afford highly active and enantioselective single-site solid catalysts for the asymmetric cyclization reactions of 1,6-enynes. Robust, chiral, and porous Zr-MOFs of UiO topology, BINAP-MOF (I) or BINAP-dMOF (II), were prepared using purely BINAP-derived dicarboxylate linkers or by mixing BINAP-derived linkers with unfunctionalized dicarboxylate linkers, respectively. Upon metalation with Rh(nbd)2BF4 and [Rh(nbd)Cl]2/AgSbF6, the MOF precatalysts I·Rh(BF4) and I·Rh(SbF6) efficiently catalyzed highly enantioselective (up to 99% ee) reductive cyclization and Alder-ene cycloisomerization of 1,6-enynes, respectively. I·Rh catalysts afforded cyclization products at comparable enantiomeric excesses (ee's) and 4-7 times higher catalytic activity than the homogeneous controls, likely a result of catalytic site isolation in the MOF which prevents bimolecular catalyst deactivation pathways. However, I·Rh is inactive in the more sterically encumbered Pauson-Khand reactions between 1,6-enynes and carbon monoxide. In contrast, with a more open structure, Rh-functionalized BINAP-dMOF, II·Rh, effectively catalyzed Pauson-Khand cyclization reactions between 1,6-enynes and carbon monoxide at 10 times higher activity than the homogeneous control. II·Rh was readily recovered and used three times in Pauson-Khand cyclization reactions without deterioration of yields or ee's. Our work has expanded the scope of MOF-catalyzed asymmetric reactions and showed that the mixed linker strategy can effectively enlarge the open space around the catalytic active site to accommodate highly sterically demanding polycyclic metallocycle transition states/intermediates in asymmetric intramolecular cyclization reactions. PMID:26335305

  8. Robust, Chiral, and Porous BINAP-Based Metal–Organic Frameworks for Highly Enantioselective Cyclization Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Sawano, Takahiro; Thacker, Nathan C.; Lin, Zekai; McIsaac, Alexandra R.; Lin, Wenbin (UC)

    2016-05-06

    We report here the design of BINAP-based metal–organic frameworks and their postsynthetic metalation with Rh complexes to afford highly active and enantioselective single-site solid catalysts for the asymmetric cyclization reactions of 1,6-enynes. Robust, chiral, and porous Zr-MOFs of UiO topology, BINAP-MOF (I) or BINAP-dMOF (II), were prepared using purely BINAP-derived dicarboxylate linkers or by mixing BINAP-derived linkers with unfunctionalized dicarboxylate linkers, respectively. Upon metalation with Rh(nbd)2BF4 and [Rh(nbd)Cl]2/AgSbF6, the MOF precatalysts I·Rh(BF4) and I·Rh(SbF6) efficiently catalyzed highly enantioselective (up to 99% ee) reductive cyclization and Alder-ene cycloisomerization of 1,6-enynes, respectively. I·Rh catalysts afforded cyclization products at comparable enantiomeric excesses (ee’s) and 4–7 times higher catalytic activity than the homogeneous controls, likely a result of catalytic site isolation in the MOF which prevents bimolecular catalyst deactivation pathways. However, I·Rh is inactive in the more sterically encumbered Pauson–Khand reactions between 1,6-enynes and carbon monoxide. In contrast, with a more open structure, Rh-functionalized BINAP-dMOF, II·Rh, effectively catalyzed Pauson–Khand cyclization reactions between 1,6-enynes and carbon monoxide at 10 times higher activity than the homogeneous control. II·Rh was readily recovered and used three times in Pauson–Khand cyclization reactions without deterioration of yields or ee’s. Our work has expanded the scope of MOF-catalyzed asymmetric reactions and showed that the mixed linker strategy can effectively enlarge the open space around the catalytic active site to accommodate highly sterically demanding polycyclic metallocycle transition states/intermediates in asymmetric intramolecular cyclization reactions.

  9. Ceria Based Composite Membranes for Oxygen Separation

    DEFF Research Database (Denmark)

    Gurauskis, Jonas; Ovtar, Simona; Kaiser, Andreas;

    2014-01-01

    under the large oxygen potential gradients at elevated temperatures is decisive for the future applications. The gadolinium doped cerium oxide (CGO) based composite membranes are considered as promising candidates due to inherent stability of CGO phase. The CGO matrix is a main oxygen ion transporter......; meanwhile the primary role of a secondary phase in this membrane is to compensate the low electronic conductivity of matrix at intended functioning conditions. In this work thin film (15-20 μm) composite membranes based on CGO matrix and LSF electronic conducting phase were fabricated and evaluated....... Composite thin film was deposited on tubular structural support made of porous MgO phase. Porous CGO layers (20 μm) were implemented as backbones for catalytic phase on both sides of a composite membrane (Fig. 1). During initial trials, the catalytic phase free CGO/LSF composite membranes demonstrated...

  10. Chiral symmetry

    CERN Document Server

    Ecker, G

    1999-01-01

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

  11. 冠醚固定相的制备及手性拆分%Crown ether stationary phase for chiral separation

    Institute of Scientific and Technical Information of China (English)

    伍鹏; 汤波; 路振宇; 孔娇; 袁黎明

    2015-01-01

    以 R‐联萘酚为原料合成了 R‐(1,1′‐二萘基)‐20‐冠‐6,并将其涂敷于 C18硅胶(平均粒径5μm ,孔径120 nm)上制成了可用于高效液相色谱手性拆分的 R‐(1,1′‐二萘基)‐20‐冠‐6冠醚固定相(CSP).在以 pH =2的高氯酸溶液为流动相,流速为0.1 mL ・min‐1,柱温为25℃的条件下,研究了 CSP 对9种α‐氨基酸对映体的拆分能力.实验结果表明,有5种手性氨基酸(缬氨酸、苯甘氨酸、对羟基苯甘氨酸、谷氨酸、色氨酸)得到不同程度的拆分,说明 CSP 能对手性氨基酸进行一定的拆分.%In this paper ,R‐(1 ,1′‐ binaphthyl)‐20‐crown‐6 was synthesized and coated on C18 silica gel ,which was used as the chiral stationary phase with pH = 2 perchloric acid solution as mobile phase in high performance liquid chromatography .Five α‐amino acid enantiomers (valine ,phenylglycine ,hydroxyphenylglycine ,glutamate and tryptophan) had been separated . The results showed that the R‐(1 ,1′‐ binaphthyl)‐20‐crown‐6 crown ether stationary phase (CSP) possesses a good enantioselectivity for α‐ amino acid enantiomers .

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

    CERN Document Server

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

    2016-01-01

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

  13. Punctuated Chirality

    Science.gov (United States)

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

    2008-12-01

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

  14. Punctuated Chirality

    CERN Document Server

    Gleiser, Marcelo; Walker, Sara Imari

    2008-01-01

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

  15. Chiral Quantum Optics

    CERN Document Server

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

    2016-01-01

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

  16. [Enantioseparation behavior of chiral stationary phases AD, AS and OD].

    Science.gov (United States)

    Li, Liqun; Fan, Jun; Zhang, Jing; Chen, Xiaodong; Wang, Tai; He, Jianfeng; Zhang, Weiguang

    2016-01-01

    Over the past decades, HPLC enantioseparation with chiral stationary phases (CSPs) has been widely applied in chiral analysis and preparation of new pharmaceuticals, pesticides, food, etc. Herein, enantioseparation of 20 chiral compounds have been carried out on three polysaccharide-based CSPs (EnantioPak AD, AS and OD) with normal phases by HPLC, separately. The influences of skeletal structure and the kinds of derivative groups on separation behaviors of these CSPs have been studied in detail. As results indicated, except for compound 13, the other compounds were baseline separated on EnantioPak AD, with most of resolution over 2. 0; in addition, better separation for acidic or basic compounds was achieved through adding acidic/basic additives into the mobile phase of hexane-alcohol. For four aromatic alcohols (compounds 13-16), their retention in the EnantioPak AD column showed a weakening tendency with increase of carbon number in side chain group, and the reverse trend of their resolution was observed. Furthermore, EnantioPak AD showed much better separation performance for eight compounds (13-20) than the others. In short, these results have provided some references for further investigation of separation behavior and applications of polysaccharide-based CSPs. PMID:27319174

  17. Chiral Nanoscience and Nanotechnology

    OpenAIRE

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

    2008-01-01

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

  18. A Separated Domain-Based Kernel Model for Trusted Computing

    Institute of Scientific and Technical Information of China (English)

    FANG Yanxiang; SHEN Changxiang; XU Jingdong; WU Gongyi

    2006-01-01

    This paper fist gives an investigation on trusted computing on mainstream operation system (OS). Based on the observations, it is pointed out that Trusted Computing cannot be achieved due to the lack of separation mechanism of the components in mainstream OS. In order to provide a kind of separation mechanism, this paper proposes a separated domain-based kernel model (SDBKM), and this model is verified by non-interference theory. By monitoring and simplifying the trust dependence between domains, this model can solve problems in trust measurement such as deny of service (DoS) attack, Host security, and reduce the overhead of measurement.

  19. A chiral photochromic Schiff base: (R)-4-meth-oxy-2-[(1-phenyl-ethyl)imino-meth-yl]phenol.

    Science.gov (United States)

    Miura, Yukie; Aritake, Yoshikazu; Akitsu, Takashiro

    2009-01-01

    The title chiral photochromic Schiff base compound, C(16)H(17)NO(2), was synthesized from (R)-1-phenyl-ethyl-amine and 5-methoxy-salicylaldehyde. The mol-ecule of the title compound exists in the phenol-imine tautomeric form. The dihedral angle between the two aromatic rings is 62.61 (11)°. An intra-molecular O-H⋯N hydrogen bond with an O⋯N distance of 2.589 (2) Å is observed. The crystal packing is stabilized by C-H⋯π inter-actions involving the aromatic ring. PMID:21577845

  20. Herzberg Circuit and Berry's Phase in Chirality-based Coded Qubit in a Triangular Triple Quantum Dot

    OpenAIRE

    Hsieh, Chang-Yu; Rene, Alexandre; Hawrylak, Pawel

    2011-01-01

    We present a theoretical proposal for the Herzberg circuit and controlled accumulation of Berry's phase in a chirality-based coded qubit in a triangular triple quantum dot molecule with one electron spin each. The qubit is encoded in the two degenerate states of a three spin complex with total spin $S=1/2$. Using a Hubbard and Heisenberg model the Herzberg circuit encircling the degeneracy point is realized by adiabatically tuning the successive on-site energies of quantum dots and tunnel cou...

  1. Electromagnetic Response of the Chiral Magnetic Effect in Weyl Semimetals

    CERN Document Server

    Barnes, Edwin; Minic, Djordje

    2016-01-01

    Weyl semimetals are predicted to realize the three-dimensional axial anomaly first discussed in particle physics. The anomaly leads to unusual transport phenomena such as the chiral magnetic effect in which an applied magnetic field induces a current parallel to the field. Here we investigate diagnostics of the axial anomaly based on the fundamental equations of axion electrodynamics. We find that materials with Weyl nodes of opposite chirality and finite energy separation immersed in a uniform magnetic field exhibit an anomaly-induced oscillatory magnetic field with a period set by the chemical potential difference of the nodes. In the case where a chemical potential imbalance is created by applying parallel electric and magnetic fields, we find a suppression of the magnetic field component parallel to the electric field inside the material for rectangular samples, suggesting that the chiral magnetic current opposes this imbalance. For cylindrical geometries, we instead find an enhancement of this magnetic f...

  2. Effect of the water content on the retention and enantioselectivity of albendazole and fenbendazole sulfoxides using amylose-based chiral stationary phases in organic-aqueous conditions.

    Science.gov (United States)

    Materazzo, Sabrina; Carradori, Simone; Ferretti, Rosella; Gallinella, Bruno; Secci, Daniela; Cirilli, Roberto

    2014-01-31

    Four commercially available immobilized amylose-derived CSPs (Chiralpak IA-3, Chiralpak ID-3, Chiralpak IE-3 and Chiralpak IF-3) were used in the HPLC analysis of the chiral sulfoxides albendazole (ABZ-SO) and fenbendazole (FBZ-SO) and their in vivo sulfide precursor (ABZ and FBZ) and sulfone metabolite (ABZ-SO2 and FBZ-SO2) under organic-aqueous mode. U-shape retention maps, established by varying the water content in the acetonitrile- and ethanol-water mobile phases, were indicative of two retention mechanisms operating on the same CSP. The dual retention behavior of polysaccharide-based CSPs was exploited to design greener enantioselective and chemoselective separations in a short time frame. The enantiomers of ABZ-SO and FBZ-SO were baseline resolved with water-rich mobile phases (with the main component usually being 50-65% water in acetonitrile) on the IF-3 CSP and ethanol-water 100:5 mixture on the IA-3 and IE-3 CSPs. A simultaneous separation of ABZ (or FBZ), enantiomers of the corresponding sulfoxide and sulfone was achieved on the IA-3 using ethanol-water 100:60 (acetonitrile-water 100:100 for FBZ) as a mobile phase.

  3. On Chiral Space Groups and Chiral Molecules

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

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

  4. 安非他明类毒品的手性对映体气相色谱-质谱分析%Enantiomer Separation and Determination of Amphetamines with Chiral Derivatization by Gas Chromatography-Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    孟品佳

    2001-01-01

    采用手性衍生化试剂:(S)(-)N-三氟乙酰-1-脯胺酰氯(TPC)和(R)(+)-α-甲氯基-α-三氟甲基苯乙酸(MTPA)与安非他明类对映体反应生成非对映体衍生化产物,通过常规的GC/MS方法将其分离。本文较系统地考察了这两种手性试剂衍生化反应中溶剂、手性试剂用量、加热温度、反应时间等因素对安非他明类对映体衍生化结果的影响。实现了Am、MAm、MDA、MDMA、MDEA、MBDB等几种毒品对映体间的良好分离。%Most drugs of amphetamines contain chiral centers, which form different optical isomers, or enantiomers. Because different enantiomers have different pharmcological effect and have different machnism of metabolism. Besides, the ratio of the two eanatiomers could reflect the route and method used in the synthesis of the drugs. So the separation and determination of these eanantiomers for seizured samples or for biological samples became very important in the sence of forensic science.The paper used two chiral reagents: N-trifluroacetylprolyl chloride (TPC) and ( R )-( + )-α-methoxy-α-(trifluormethyl)phenylacetic acid (MTPA) to reach the purpose. They reacted with amphetamine enantiomers to form diasteromeric pairs, which possess some diffeences in physical and chemical natures and could be separated by GC/MS. The paper examined in detail some fectors such as the solvents, chiral reagent amounts, reaction time,temperature,etc. on the effect of chiral derivatization. Some enantiomers of amphetamine (Am),N-methylamphetamine(MAm),3,4-methylenedioxyamphetamin (MDA), 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3, 4-methylenedioxy-N-ethylamphetamine ( MDEA ) and N-methyl-1-( 3, 4-methylenedioxy )-2-butanamine (MBDB) were well separated each other.

  5. Ultra-fast high-efficiency enantioseparations by means of a teicoplanin-based chiral stationary phase made on sub-2 μm totally porous silica particles of narrow size distribution.

    Science.gov (United States)

    Ismail, Omar H; Ciogli, Alessia; Villani, Claudio; De Martino, Michela; Pierini, Marco; Cavazzini, Alberto; Bell, David S; Gasparrini, Francesco

    2016-01-01

    A new ultra-high performance teicoplanin-based stationary phase was prepared starting from sub-2 μm totally porous silica particles of narrow size distribution. Columns of different lengths were packed at high pressure and a deep and systematic evaluation of kinetic performance, in terms of van Deemter analysis, was performed under different elution conditions (HILIC, POM, RP and NP) by using both achiral and chiral probes. For the achiral probes, the efficiency of the columns at the minimum of the van Deemter curves were very high leading to some 278,000, 270,000, 262,000 and 232,000 plates/m in hydrophilic interaction liquid chromatography (HILIC), polar organic mode (POM), normal phase (NP) and reversed phase (RP) respectively. The lowest plate height, Hmin=3.59 μm (h(/)=1.89), was obtained under HILIC conditions at a flow rate of 1.4 mL/min. Efficiency as high as 200,000-250,000 plates/m (at the optimum flow rate) was obtained in the separation of the enantiomers of chiral probes under HILIC/POM conditions. N-protected amino acids, α-aryloxy acids, herbicides, anti-inflammatory agents were baseline separated on short (2-cm) and ultra-short (1-cm) columns, with analysis time in the order of 1 min. The enantiomers of N-BOC-d,l-methionine were successfully baseline separated in only 11s in HILIC mode. Several examples of fast and efficient resolutions in sub/supercritical fluid chromatography were also obtained for a range of chiral carboxylic acids. PMID:26687167

  6. Ultra-fast high-efficiency enantioseparations by means of a teicoplanin-based chiral stationary phase made on sub-2 μm totally porous silica particles of narrow size distribution.

    Science.gov (United States)

    Ismail, Omar H; Ciogli, Alessia; Villani, Claudio; De Martino, Michela; Pierini, Marco; Cavazzini, Alberto; Bell, David S; Gasparrini, Francesco

    2016-01-01

    A new ultra-high performance teicoplanin-based stationary phase was prepared starting from sub-2 μm totally porous silica particles of narrow size distribution. Columns of different lengths were packed at high pressure and a deep and systematic evaluation of kinetic performance, in terms of van Deemter analysis, was performed under different elution conditions (HILIC, POM, RP and NP) by using both achiral and chiral probes. For the achiral probes, the efficiency of the columns at the minimum of the van Deemter curves were very high leading to some 278,000, 270,000, 262,000 and 232,000 plates/m in hydrophilic interaction liquid chromatography (HILIC), polar organic mode (POM), normal phase (NP) and reversed phase (RP) respectively. The lowest plate height, Hmin=3.59 μm (h(/)=1.89), was obtained under HILIC conditions at a flow rate of 1.4 mL/min. Efficiency as high as 200,000-250,000 plates/m (at the optimum flow rate) was obtained in the separation of the enantiomers of chiral probes under HILIC/POM conditions. N-protected amino acids, α-aryloxy acids, herbicides, anti-inflammatory agents were baseline separated on short (2-cm) and ultra-short (1-cm) columns, with analysis time in the order of 1 min. The enantiomers of N-BOC-d,l-methionine were successfully baseline separated in only 11s in HILIC mode. Several examples of fast and efficient resolutions in sub/supercritical fluid chromatography were also obtained for a range of chiral carboxylic acids.

  7. Enantiomeric Separation of Saklmererol by HPLC Using a-Acid Glycoprotein Chiral Atationary Phase%α1-酸性糖蛋白柱拆分沙美特罗对映体

    Institute of Scientific and Technical Information of China (English)

    杨永健; 侯美琴

    2001-01-01

    To develop an enantionmeric sepatration mentod of salmeterol by HPLC using -acid glycopratein (a1-AGP )chiral stationary phase Method :Indluences of the pH value of the mobile phase organic modifiers,ans floe rate on the enantionmetric sparation of salmerterol using a1-AGP chiral straruionary phase were investigared Resulte :Salmeeterol enanhtiometric were separated on an a1-AGP chiral statonary phase colunmn with a moblie phase constsed of to mmol.l-1 NaAc(pH4.0)-isopropanol (98:2) at a flow rate of 0.9 ml.min-1 Conclustion :The pH value of the mobile phase and teh organic modifier concentration were vwery imporation parameteers when optimzing the enantomene sep-aration of thew cationic racem,metes Higher column efficiency was obtainde with lower flow rates%目的:建立沙美特罗对映体拆分方法。方法:以α1-酸性糖蛋白(α1-AGP)为固定相,考察了流动相pH、有机改性剂及流速对分离的影响。结果:以10 mmol.L-1醋酸钠(pH 4.0)-异丙醇(98∶2)为流动相,流速为0.9 mL.min-1,在α1-AGP柱上拆分了沙美特罗。结论:流动相pH和有机改性剂的量是优化分离带正电荷对映体的分离的重要因素。同时可以在一定的流速范围内通过调节流速来提高柱效、改善分离。

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  9. Towards the chiral metabolomics: Liquid chromatography–mass spectrometry based DL-amino acid analysis after labeling with a new chiral reagent, (S)-2,5-dioxopyrrolidin-1-yl-1-(4,6-dimethoxy-1,3,5-triazin-2-yl) pyrrolidine-2-carboxylate, and the application to saliva of healthy volunteers

    International Nuclear Information System (INIS)

    Highlights: • A novel chiral labeling reagent was synthesized. • Analysis of DL-amino acids was performed by UPLC–ESI-MS/MS. • Efficient enantioseparation and detection of DL-amino acids were performed. • DL-Amino acid in saliva was successfully determined under mild conditions. - Abstract: A novel triazine-type chiral derivatization reagent, i.e., (S)-2,5-dioxopyrrolidin-1-yl-1-(4,6-dimethoxy-1,3,5-triazin-2-yl) pyrrolidine-2-carboxylate (DMT-(S)-Pro-OSu), was developed for the highly sensitive and selective detection of chiral amines and amino acids by UPLC–MS/MS analysis. The enantiomers of amino acids were easily labeled with the reagents at room temperature within 40 min in an alkaline medium containing triethylamine. The diastereomers derived from proteolytic amino acids, except serine, were well separated under isocratic elution conditions by reversed-phase chromatography using an ODS column (Rs = 1.2–9.0). DL-Serine was separated by use of an ADME column which has relatively higher polar surface than the conventional ODS column. The characteristic product ions, i.e., m/z 195.3 and m/z 209.3, were detected from all the diastereomers by the collision-induced dissociation of the protonated molecule. A highly sensitive detection on the amol–fmol level was obtained from the selected reaction monitoring (SRM) chromatogram. The chiral amines (e.g., adrenaline and noradrenaline) labeled with DMT-(S)-Pro-OSu were also well separated and sensitively detected by the present procedure. The method using DMT-(S)-Pro-OSu was used for the determination of DL-amino acids in the human saliva from healthy volunteers. Various L-amino acids were identified in the saliva. Furthermore, D-alanine (D-Ala) and D-proline (D-Pro) were also detected in relatively high concentrations (>5%). The ratio was higher in male saliva than in female saliva. However, the difference in the ratio of D-Ala for one day was not very high and the effect of foods and beverage seemed to

  10. Towards the chiral metabolomics: Liquid chromatography–mass spectrometry based DL-amino acid analysis after labeling with a new chiral reagent, (S)-2,5-dioxopyrrolidin-1-yl-1-(4,6-dimethoxy-1,3,5-triazin-2-yl) pyrrolidine-2-carboxylate, and the application to saliva of healthy volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Toshiki; Takayama, Takahiro; Todoroki, Kenichiro; Inoue, Koichi; Min, Jun Zhe; Toyo’oka, Toshimasa, E-mail: toyooka@u-shizuoka-ken.ac.jp

    2015-05-22

    Highlights: • A novel chiral labeling reagent was synthesized. • Analysis of DL-amino acids was performed by UPLC–ESI-MS/MS. • Efficient enantioseparation and detection of DL-amino acids were performed. • DL-Amino acid in saliva was successfully determined under mild conditions. - Abstract: A novel triazine-type chiral derivatization reagent, i.e., (S)-2,5-dioxopyrrolidin-1-yl-1-(4,6-dimethoxy-1,3,5-triazin-2-yl) pyrrolidine-2-carboxylate (DMT-(S)-Pro-OSu), was developed for the highly sensitive and selective detection of chiral amines and amino acids by UPLC–MS/MS analysis. The enantiomers of amino acids were easily labeled with the reagents at room temperature within 40 min in an alkaline medium containing triethylamine. The diastereomers derived from proteolytic amino acids, except serine, were well separated under isocratic elution conditions by reversed-phase chromatography using an ODS column (R{sub s} = 1.2–9.0). DL-Serine was separated by use of an ADME column which has relatively higher polar surface than the conventional ODS column. The characteristic product ions, i.e., m/z 195.3 and m/z 209.3, were detected from all the diastereomers by the collision-induced dissociation of the protonated molecule. A highly sensitive detection on the amol–fmol level was obtained from the selected reaction monitoring (SRM) chromatogram. The chiral amines (e.g., adrenaline and noradrenaline) labeled with DMT-(S)-Pro-OSu were also well separated and sensitively detected by the present procedure. The method using DMT-(S)-Pro-OSu was used for the determination of DL-amino acids in the human saliva from healthy volunteers. Various L-amino acids were identified in the saliva. Furthermore, D-alanine (D-Ala) and D-proline (D-Pro) were also detected in relatively high concentrations (>5%). The ratio was higher in male saliva than in female saliva. However, the difference in the ratio of D-Ala for one day was not very high and the effect of foods and beverage

  11. Studies of a pyridino-crown ether-based chiral stationary phase on the enantioseparation of biogenic chiral aralkylamines and α-amino acid esters by high-performance liquid chromatography.

    Science.gov (United States)

    Lévai, Sándor; Németh, Tamás; Fődi, Tamás; Kupai, József; Tóth, Tünde; Huszthy, Péter; Balogh, György Tibor

    2015-11-10

    This paper reports the enantioseparation ability of a pyridino-18-crown-6 ether-based chiral stationary phase [(S,S)-CSP-1]. The enantiomeric discrimination of chiral stationary phase (S,S)-CSP-1 was evaluated by HPLC using the mixtures of enantiomers of various protonated primary aralkylamines [1-phenylethylamine hydrogen perchlorate (PEA), 2,3-dihydro-1H-inden-1-amine (1-aminoindan), 2,2'-(1,2-diaminoethane-1,2-diyl) diphenol (HPEN)] and perchlorate salts of α-amino acid esters [alanine benzyl ester (Ala-OBn), phenylalanine benzyl ester (Phe-OBn), phenylalanine methyl ester (Phe-OMe), phenylglycine methyl ester (PhGly-OMe), glutamic acid dibenzyl ester (Glu-diOBn), and valine benzyl ester (Val-OBn)]. The best enantioseparation was achieved in the case of PEA. The high enantioselectivity was rationalized by the strong π-π interaction of the extended π system of the aryl-substituted pyridine unit. PMID:26218505

  12. Separations systems data base: a users' manual. Revision I

    International Nuclear Information System (INIS)

    A separations systems data base (SEPSYS), designed specifically for the retrieval of information needed in chemical separations problems (i.e., how to perform a given separation under given conditions), is described. Included are descriptions of the basic methods of searching and retrieving information from the data base, the procedure for entering records into the data base, a listing of additional references concerning the computer information process, and an example of a typical record. The initial entries are concerned primarily with liquid-liquid extraction and liquid-solid ion exchange methods for metal ions and salts; however, the data base is constructed so that almost any separation process can be accommodated. Each record is indexed with information provided under the following fields: author; title; publication source; data of publication; organization sponsoring the work; brief abstract of the work; abstract number if the work has been so referenced, and/or abstractors initials; type of separation system used (e.g., flotation); specific or generic name of the separation agent used (e.g., acetylacetone); list of substances separated (e.g., gold, copper); qualitative description of the supporting medium or matrix containing the substances before separation (e.g., nitrate); type of literature where the record was printed (e.g., book); and type of information that the article contains. Each of these fields may be searched independently of the others (or in combination), and the last six fields contain specific key words that are listed in the report. Definitions are provided for the 36 information terms

  13. Separations based on the mechanical forces of light.

    Science.gov (United States)

    Zhao, Bum Suk; Koo, Yoon-Mo; Chung, Doo Soo

    2006-01-18

    A photon as a particle has an energy and a momentum. In a matter-photon interaction, the matter and photons may exchange their momenta observing the momentum conservation law. The consequence of the momentum transfer from a photon to a matter particle is a mechanical force exerted on the particle. Several separation methods based on this force of light are reviewed. Photophoresis separations for micron-sized particles and optical force chromatography for chemical-sized molecules are discussed. PMID:17723334

  14. Resolution of the Chiral Drugs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  15. Resolution of the Chiral Drugs

    Institute of Scientific and Technical Information of China (English)

    DENG; JinGen

    2001-01-01

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

  16. Synthetic Applications of Chiral Furanboronate

    Institute of Scientific and Technical Information of China (English)

    CHAN; KinFai

    2001-01-01

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

  17. Hollow fibre supported liquid membrane based separations of actinides

    International Nuclear Information System (INIS)

    Renaissance in nuclear energy is poised to make a significant contribution to the diversification of clean energy resources and to reduce the burden of CO2 in atmosphere. Its sustainability lies in using nature's mineral resources in an efficient and environmentally friendly way. One of the major challenges in the nuclear energy programme has, however, been the management of radioactive waste in a manner which allays apprehensions about its adverse impact on the environment. Innovative approaches are being devised internationally to treat spent nuclear fuel as a source of valuables. Separation of long-lived radionuclides such as actinides and fission products from high level radioactive waste is a challenging task for the chemists working on the reprocessing and waste management processes involved at the tail end of nuclear fuel cycle. Amongst the various separation techniques, liquid membrane based separation methods are becoming increasingly popular due to factors such as ligand economy, high efficiency and low power consumption. Techniques such as emulsion liquid membrane and hollow fibre based non-dispersive solvent extraction methods are reported to be more efficient than the solvent extraction based separation methods which have limitations of emulsion/third phase or crud formation. In the present article, an attempt has been made to review the work carried out internationally as well as in the author's laboratory on liquid membrane based actinides separations during last few years with a particular focus on the use of hollow fibre supported liquid membranes. (author)

  18. Punctuated Chirality

    OpenAIRE

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

    2008-01-01

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

  19. Preparation and separation of DNA-wrapped carbon nanotubes.

    Science.gov (United States)

    Ao, Geyou; Zheng, Ming

    2015-01-01

    Purification of single-chirality single-wall carbon nanotubes (SWCNTs) from their synthetic mixture is a prerequisite for many applications. DNA-controlled carbon nanotube (CNT) purification has evolved over a decade along with other separation techniques utilizing different types of dispersing agents such as surfactants and polymers. The size of single-stranded DNA (ssDNA) libraries affords practically unlimited ways of coating SWCNTs. Recent developments in separating surfactant-dispersed SWCNTs by polymer aqueous two-phase (ATP) extraction has enabled rapid and efficient SWCNT separation on a larger volume scale. Applying the ATP separation method to DNA-SWCNT hybrids opens a new route for effective sorting of nanotubes into each and every single-chirality species. Here, we report protocols for purifying as many as 15 single-chirality nanotube species from a synthetic mixture based on the separation of DNA-SWCNTs by the aqueous two-phase (ATP) method.

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

    Science.gov (United States)

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

    2015-12-01

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

  1. Ultra-broad band and dual-band highly efficient polarization conversion based on the three-layered chiral structure

    Science.gov (United States)

    Xu, Kai-kai; Xiao, Zhong-yin; Tang, Jing-yao; Liu, De-jun; Wang, Zi-hua

    2016-07-01

    In the paper, a novel three-layered chiral structure is proposed and investigated, which consists of a split-ring resonator sandwiched between two layers of sub-wavelength gratings. This designed structure can achieve simultaneously asymmetric transmission with an extremely broad bandwidth and high amplitude as well as multi-band 90° polarization rotator with very low dispersion. Numerical simulations adopted two kinds of softwares with different algorithms demonstrate that asymmetric parameter can reach a maximum of 0.99 and over than 0.8 from 4.6 to 16.8 GHz, which exhibit magnitude and bandwidth improvement over previous chiral metamaterials in microwave bands (S, C, X and Ku bands). Specifically, the reason of high amplitude is analyzed in detail based on the Fabry-perot like resonance. Subsequently, the highly efficient polarization conversion with very low dispersion between two orthogonal linearly polarized waves is also analyzed by the optical activity and ellipticity. Finally, the electric fields are also investigated and further demonstrate the correctness of the simulated and calculated results.

  2. High-performance liquid chromatographic enantioseparation of cyclic β-aminohydroxamic acids on zwitterionic chiral stationary phases based on Cinchona alkaloids.

    Science.gov (United States)

    Lajkó, Gyula; Orosz, Tímea; Grecsó, Nóra; Fekete, Beáta; Palkó, Márta; Fülöp, Ferenc; Lindner, Wolfgang; Péter, Antal; Ilisz, István

    2016-05-19

    Cyclic β-aminohydroxamic acid enantiomer pairs were stereoselectively separated by high-performance liquid chromatography on the recently developed Cinchona alkaloid-based zwitterionic chiral stationary phases Chiralpak ZWIX(+)™, ZWIX(-)™, ZWIX(+A) and ZWIX(-A). The results of variation of the applied chromatographic conditions, such as the bulk solvent composition, the concentrations and ratio of the acid and base additives, the presence of water as mobile phase additive and the counter-ion concentration furnished a better understanding of the retention mechanism. A thermodynamic study in the temperature range 5-50 °C revealed enthalpy-controlled enantiodiscrimination in all cases. The structure-selectivity relationships clearly indicated the importance of the strereochemistry of the functional groups. From an enantiorecognition aspect, the diexo position of the functional groups always proved more favorable than the diendo position. The elution sequence was determined in all cases and was found to reversed when ZWIX(+)™ was changed to ZWIX(-)™ or ZWIX(+A) to ZWIX(-A).

  3. Pion properties at finite nuclear density based on in-medium chiral perturbation theory

    CERN Document Server

    Goda, Soichiro

    2013-01-01

    The in-medium pion properties, {\\it i.e.} the temporal pion decay constant $f_t$, the pion mass $m_\\pi^*$ and the wave function renormalization, in symmetric nuclear matter are calculated in an in-medium chiral perturbation theory up to the next-to-leading order of the density expansion $O(k_F^4)$. The chiral Lagrangian for the pion-nucleon interaction is determined in vacuum, and the low energy constants are fixed by the experimental observables. We carefully define the in-medium state of the pion and find that the pion wave function plays an essential role for the in-medium pion properties. We show that the linear density correction is dominated and the next-leading corrections is not so large at the saturation density, while their contributions can be significant in higher densities. The main contribution of the next-leading order comes from the double scattering term. We also discuss whether the low energy theorems, the Gell-Mann--Oakes--Renner relation and the Glashow--Weinberg relation, are satisfied in...

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

    Institute of Scientific and Technical Information of China (English)

    Tomoyuki IKAI; Takayuki YAMADA

    2016-01-01

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

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

    Science.gov (United States)

    Wu, Lianming; Vogt, Frederick G

    2012-10-01

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

  6. Comparison of the Separation Performances of Cinchona Alkaloid-Based Zwitterionic Stationary Phases in the Enantioseparation of β2- and β3-Amino Acids

    Directory of Open Access Journals (Sweden)

    István Ilisz

    2014-12-01

    Full Text Available The enantiomers of twelve unusual β2- and β3-homoamino acids containing the same side-chains were separated on chiral stationary phases containing a quinine- or quinidine-based zwitterionic ion-exchanger as chiral selector. The effects of the mobile phase composition, the nature and concentration of the acid and base additives and temperature on the separations were investigated. The changes in standard enthalpy, ∆(∆H°, entropy, ∆(∆S°, and free energy, ∆(∆G°, were calculated from the linear van’t Hoff plots derived from the ln α vs. 1/T curves in the studied temperature range (10–50 °C. The values of the thermodynamic parameters depended on the nature of the selectors, the structures of the analytes, and the positions of the substituents on the analytes. A comparison of the zwitterionic stationary phases revealed that the quinidine-based ZWIX(−™ column exhibited much better selectivity for both β2- and β3-amino acids than the quinine-based ZWIX(+™ column, and the separation performances of both the ZWIX(+™ and ZWIX(−™ columns were better for β2-amino acids. The elution sequence was determined in some cases and was observed to be R < S and S < R on the ZWIX(+™ and ZWIX(−™ columns, respectively.

  7. Chiral geometry in multiple chiral doublet bands

    CERN Document Server

    Zhang, Hao

    2015-01-01

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

  8. Enantiomeric Separation and Determination of the Enantiomeric Impurity of Armodafinil by Capillary Electrophoresis with Sulfobutyl Ether-β-cyclodextrin as Chiral Selector

    Directory of Open Access Journals (Sweden)

    Bingren Xiang

    2011-12-01

    Full Text Available A selective capillary electrophoresis method using sulfobutyl ether-β-cyclodextrin as a chiral selector was developed and validated for the determination of the enantiomeric impurity of (R-modafinil, i.e., armodafinil. Several parameters were optimized for a satisfactory enantioresolution, including the type and concentration of chiral selector and organic modifier, pH of background electrolyte (BGE, capillary temperature. The finally adopted condition was: 20 mmol/L phosphate buffer at pH 7.5, containing 20 mmol/L sulfobutyl ether-β-cyclodextrin and 20% methanol, at temperature of 25 °C. A good resolution of 3.3 for the two enantiomers of modafinil was achieved by applying the optimal conditions. The limit of detection (LOD and limit of quantification (LOQ of (S-modafinil were 1.25 μg/mL and 2.50 μg/mL, respectively. The established method was also proven to display good selectivity, repeatability, linearity and accuracy. Finally, the method was used to investigate the enantiomeric purity of armodafinil in bulk samples.

  9. Improved Separability Criteria Based on Bloch Representation of Density Matrices.

    Science.gov (United States)

    Shen, Shu-Qian; Yu, Juan; Li, Ming; Fei, Shao-Ming

    2016-01-01

    The correlation matrices or tensors in the Bloch representation of density matrices are encoded with entanglement properties. In this paper, based on the Bloch representation of density matrices, we give some new separability criteria for bipartite and multipartite quantum states. Theoretical analysis and some examples show that the proposed criteria can be more efficient than the previous related criteria. PMID:27350031

  10. HYDROGEN BONDING IN POLYMERIC ADSORBENTS BASED ADSORPTION AND SEPARATION

    Institute of Scientific and Technical Information of China (English)

    XUMancai; SHIZuoqing; 等

    2000-01-01

    After a concise introduction of hydrogen bonding effects in solute-solute and solute-solvent bonding,the design of polymeric adsorbents based on hydrogen bonding ,selectivity in adsorption through hydrogen bonding,and characterization of hydrogen bonding in adsorption and separation were reviewed with 28 references.

  11. Enantioselective analysis of non-steroidal anti-inflammatory drugs in freshwater fish based on microextraction with a supramolecular liquid and chiral liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Caballo, Carmen; Sicilia, Maria Dolores; Rubio, Soledad

    2015-06-01

    Toxicity of pharmaceuticals to aquatic biota is still largely unknown, and no research on the stereoselective toxicity of chiral drugs to these organisms has been undertaken to date. Because of the lack of analytical methods available for this purpose, this manuscript deals, for the first time, with the enantioselective analysis of the non-steroidal anti-inflammatory drugs (NSAIDs) ibuprofen, naproxen and ketoprofen in freshwater fish. The method was based on the microextraction of NSAIDs from fish muscle with a supramolecular liquid made up of inverted hexagonal aggregates of decanoic acid, their enantiomeric separation by liquid chromatography onto a (R)-1-naphthylglycine and 3,5-dinitrobenzoic acid stationary phase and quantification by tandem mass spectrometry. Limits of quantitation (LOQs) for NSAID enantiomers were in the range 1.7-3.3 ng g(-1). Absolute recoveries were from 97 to 104 %, which indicated the high extraction efficiency of the supramolecular solvent. Extraction equilibrium conditions were reached after 10 min which permitted fast sample treatment. Relative standard deviations for enantiomers in fish muscle were always below 6 %. Isotopically labelled internal standards were used to compensate for matrix interferences. The method in-house validation was carried out with the Oncorhynchus mykiss species, and it was applied to the determination of NSAID enantiomers in different fortified freshwater fish species (Alburnus alburnus, Lepomis gibbosus, Micropterus salmoides, O. mykiss and Cyprinus carpio). PMID:25869485

  12. Musical Sound Separation Based on Binary Time-Frequency Masking

    Directory of Open Access Journals (Sweden)

    Wang DeLiang

    2009-01-01

    Full Text Available The problem of overlapping harmonics is particularly acute in musical sound separation and has not been addressed adequately. We propose a monaural system based on binary time-frequency masking with an emphasis on robust decisions in time-frequency regions, where harmonics from different sources overlap. Our computational auditory scene analysis system exploits the observation that sounds from the same source tend to have similar spectral envelopes. Quantitative results show that utilizing spectral similarity helps binary decision making in overlapped time-frequency regions and significantly improves separation performance.

  13. Single channel blind source separation based on ICA feature extraction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new technique is proposed to solve the blind source separation (BSS) given only a single channel observation. The basis functions and the density of the coefficients of source signals learned by ICA are used as the prior knowledge. Based on the learned prior information the learning rules of single channel BSS are presented by maximizing the joint log likelihood of the mixed sources to obtain source signals from single observation,in which the posterior density of the given measurements is maximized. The experimental results exhibit a successful separation performance for mixtures of speech and music signals.

  14. A simple reason based on supersymmetry for replication of chiral families

    Science.gov (United States)

    Babu, K. S.; Pati, Jogesh C.; Stremnitzer, Hanns

    1991-03-01

    In the context of the minimal flavon-chromon preon model, we show that supersymmetry, because of fermion-boson pairing in its field content, provides a rather simple reason for replication of composite quark-lepton families. At the level of minimum number of core constituents, which turns out to be three, it also provides a good reason why one may expect to have just three light chiral families. One crucial prediction is that there must exist complete vector-like families with mass of order 1 TeV for quark-like and few hundred GeV for lepton-like members. This can be tested at SSC, LHC and future high energy e-e+ machines.

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

    Science.gov (United States)

    Mori, Tadashi; Inoue, Yoshihisa

    The chiroptical properties, such as electronic and vibrational circular dichroism and optical rotation, of planar chiral cyclophanes have attracted much attention in recent years. Although the chemistry of cyclophanes has been extensively explored for more than 60 years, the studies on chiral cyclophanes are rather limited. Experimentally, the use of chiral stationary phases in HPLC becomes more popular and facilitates the enantiomer separation of chiral cyclophanes of interest. Almost all chiral cyclophanes can be readily separated, in analytical and preparative scales, most typically on a Daicel OD type column, which is based on cellulose tris(3,5-dimethylphenylcarbamate). The CD spectra of chiral cyclophanes are unique in their fairly large, significantly coupled Cotton effects observed in all the 1 B b, 1 L a, and 1 L b band regions. Theoretically, the time-dependent density functional theory, or TD-DFT, method becomes a cost-efficient, yet accurate, theoretical method to reproduce the electronic circular dichroisms and the absorption spectra of a variety of cyclophanes. The direct comparison of the experimental CD spectra with the theoretical ones readily leads to the unambiguous assignment of the absolute configuration of cyclophanes. In addition, the analysis of configuration interaction and molecular orbitals allows detailed interpretation of the electronic transitions and Cotton effects in the UV and CD spectra. Through the study of the CD spectra of chiral cyclophanes as model systems, the effects of intra- and intermolecular interactions on the chiroptical properties of molecules can be explored, and the results thus obtained are valuable in comprehensively elucidating the structure-chiroptical property relationship. In this review the recent progress in experimental and theoretical investigations of the electronic CD spectra of chiral cyclophanes is discussed.

  16. A PC based control system for the CERN ISOLDE separators

    International Nuclear Information System (INIS)

    The control system of the two isotope separators of CERN, named ISOLDE, is being completely redesigned with the goal of having a flexible, high performance and inexpensive system. A new architecture that makes heavy use of the commercial software and hardware available for the huge Personal Computer (PC) market is being implemented on the 1700 geographically distributed control channels of the separators. 8 MS-DOSTM i386-based PCs with about 80 acquisition/control boards are used to access the equipments while 3 other PCs running Microsoft WindowsTM and Microsoft ExcelTM are used as consoles, the whole through a NovellTM Local Area Network with a PC Disk Server used as a database. This paper describes the interesting solutions found and discusses the reduced programming work load and costs that are expected to build the system before the start of the separators in March 1992. (author)

  17. Application of Satellite Based Augmentation Systems to Altitude Separation

    Science.gov (United States)

    Magny, Jean Pierre

    This paper presents the application of GNSS1, or more precisely of Satellite Based Augmentation Systems (SBAS), to vertical separation for en-route, approach and landing operations. Potential improvements in terms of operational benefit and of safety are described for two main applications. First, vertical separation between en-route aircraft, which requires a system available across wide areas. SBAS (EGNOS, WAAS, and MSAS) are very well suited for this purpose before GNSS2 becomes available. And secondly, vertical separation from the ground during approach and landing, for which preliminary design principles of instrument approach procedures and safety issues are presented. Approach and landing phases are the subject of discussions within ICAO GNSS-P. En-route phases have been listed as GNSS-P future work and by RTCA for development of new equipments.

  18. Application of cyclodextrins in chiral capillary electrophoresis.

    Science.gov (United States)

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

    2014-10-01

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

  19. The first chiral diene-based metal-organic frameworks for highly enantioselective carbon-carbon bond formation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Sawano, Takahiro; Ji, Pengfei; McIsaac, Alexandra R.; Lin, Zekai; Abney, Carter W.; Lin, Wenbin [UC

    2016-02-01

    We have designed the first chiral diene-based metal–organic framework (MOF), E₂-MOF, and postsynthetically metalated E₂-MOF with Rh(I) complexes to afford highly active and enantioselective single-site solid catalysts for C–C bond formation reactions. Treatment of E₂-MOF with [RhCl(C₂H₄)₂]₂ led to a highly enantioselective catalyst for 1,4-additions of arylboronic acids to α,β-unsaturated ketones, whereas treatment of E₂-MOF with Rh(acac)(C₂H₄)₂ afforded a highly efficient catalyst for the asymmetric 1,2-additions of arylboronic acids to aldimines. Interestingly, E₂-MOF·Rh(acac) showed higher activity and enantioselectivity than the homogeneous control catalyst, likely due to the formation of a true single-site catalyst in the MOF. E₂-MOF·Rh(acac) was also successfully recycled and reused at least seven times without loss of yield and enantioselectivity.

  20. Preparation and chiral recognition of a novel chiral stationary phase for HPLC,based on mono(6A-N-1-(2-hydroxyl)-phenylethylimino-6A-deoxy)-β-cyclodextrin and covalently bonded silica gel

    Institute of Scientific and Technical Information of China (English)

    Xiao Ping Chen; Zhi Ming Zhou; Hao Yuan; Zi Hui Meng

    2008-01-01

    A novel chiral stationary phase (CSP) was prepared by immobilizing mono(6A-N-1-(2-hydroxyl)-phenylethylimino-6A-deoxy)-β-cyclodextrin onto the surface of silica gel via a longer spacer.This chiral stationary phase exhibited good enantios electivity for a variety of chiral compounds under reversed-phase conditions.

  1. Metolachlor stereoisomers: Enantioseparation, identification and chiral stability.

    Science.gov (United States)

    Xie, Jingqian; Zhang, Lijuan; Zhao, Lu; Tang, Qiaozhi; Liu, Kai; Liu, Weiping

    2016-09-01

    Metolachlor is a chiral herbicide consisting of four stereoisomers, which is typically used as a racemic mixture or is enriched with the herbicidally active 1'S-isomers. Because studies on the enantioselective behavior of phyto-biochemical processes and the environmental fate of metolachlor have become significant, a practical method for analyzing and separating metolachlor stereoisomers must be developed. In the present study, the enantiomeric separation of metolachlor was achieved using OD-H, AS-H, OJ-H and AY-H chiral columns. The effects of different organic modifiers in an n-hexane-based mobile phase were investigated, and various temperatures and flow rates, which may influence metolachlor separation, were also explored. The optimal resolution was obtained using an AY-H column with n-hexane/EtOH (96/4) as the mobile phase at a rate and temperature of 0.6mLmin(-1) and 25°C, respectively. The absolute configuration of the four stereoisomers was identified as αSS, αRS, αSR, αRR using computed and experimentally measured ECD and VCD spectra. Thermal interconversion and solvent stability experiments were also performed. Pure metolachlor stereoisomers in different organic solvents and water at 4°C or 30°C were stable. These results were used to establish a sound method for analyzing, preparing, characterizing, and preserving individual metolachlor stereoisomers in most natural environments. PMID:27544750

  2. 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.

  3. Synthesis, photochemical properties and DNA binding studies of dna cleaving agents based on chiral dipyridine dihydrodioxins salts

    Science.gov (United States)

    Shamaev, Alexei

    activated by UV-light. The mechanism of o-quinone release and intramolecular ET was studied in detail by methods of Ultrafast Transient Absortion Spectroscopy and supported by high-level quantum mechanical calculations. The binding properties of chiral intercalators based on PDHD to various DNA oligonucleotides were studied by various methods and DNA cleavage properties indicating strong binding and cleaving ability of the synthesized PDHDs. Also, a new method for synthesis of cyclohexa[e]pyrenes which possibly capable of intramolecular ET and electron transfer-oxidative stress (ET-OS) DNA cleavage was developed and partially accomplished.

  4. Chiral cardiovascular drugs: an overview.

    Science.gov (United States)

    Ranade, Vasant V; Somberg, John C

    2005-01-01

    Stereochemistry in drug molecules is rapidly becoming an important aspect in drug research, design, and development. Recently, individual stereoisomers of drug molecules with asymmetric centers such as fexofenadine, cetirizine, verapamil, fluoxetine, levalbutarol, and amphetamine, for example, have been separated and developed as individual drugs. These stereoisomers have different therapeutic activity, and each isomer has contributed differently with respect to its formulation's pharmacologic activity, side effects, and toxicity. The present overview discusses chirality among a select group of cardiovascular drugs, their stereochemical synthesis/preparation, isolation techniques using chiral chromatography, methods for confirmation of their enantiomeric purity, pharmacodynamics, and pharmacokinetics. Chirality has been visualized as an important factor in cardiovascular research. It is also becoming evident in other areas of therapeutics.

  5. Authenticity of raspberry flavor in food products using SPME-chiral-GC-MS

    DEFF Research Database (Denmark)

    Hansen, Anne-Mette Sølvbjerg; Frandsen, Henrik Lauritz; Fromberg, Arvid

    2015-01-01

    A fast and simple method for authenticating raspberry flavors from food products was developed. The two enantiomers of the compound (E)-α-ionone from raspberry flavor were separated on a chiral gas chromatographic column. Based on the ratio of these two enantiomers the naturalness of a raspberry...

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

    Science.gov (United States)

    Beesley, Thomas E.

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

  7. Enantioseparation of Racemic Naproxen Esters on Cellulose Tris (4-methylbenzoate) Chiral Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Several kinds of racemic naproxen ester were successfully separated on CTMB chiral stationary phase with hexane-ethanol (98:2, vol./vol.) as the mobile phase. The influence of mobile phase composition and structure of racemic naproxen ester on chiral separation was studied and the chiral recognition mechanism of CTMB was discussed.

  8. Enantioseparation of Racemic Naproxen Esters on Cellulose Tris(4—methylbenzoate) Chiral Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    BaoHaiSHAO; XiuZhuXU; 等

    2002-01-01

    Several kinds of racemic naproxen ester were successfully separated on CTMB chiral stationary phase with hexane-ethanol(98:2,vol./vol.) as the mobile phase. The influence of mobile phase composition and structure of racemic naproxen ester on chiral separation was studied and the chiral recognition mechanism of CTMB was discussed.

  9. Chiral mirrors

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-01

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

  10. Synthesis and Characterization of Water-Soluble Carboxymethyl-Cyclodextrin Polymer as Capillary Electrophoresis Chiral Selector

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The water-soluble carboxymethyl-cyclodextrin polymer (CM-CD polymer) was synthesized and used as capillary electrophoresis chiral selector.Verrapamil and thiopentorusodium were well separated using CM-CD polymer as chiral selector.

  11. Wavelet basis construction method based on separation blast vibration signal

    Institute of Scientific and Technical Information of China (English)

    凌同华; 张胜; 陈倩倩; 李洁

    2015-01-01

    As wavelet basis in wavelet analysis is neither arbitrary nor unique, the same signal dealing with different wavelet bases will generate different results. Therefore, how to construct a wavelet basis suitable for the characteristics of the analyzed signal and solve its algorithm and realization is a fundamental problem which perplexed many researchers. To solve these problems, in accordance with the basic features of the measured millisecond blast vibration signal, a new wavelet basis construction method based on the separation blast vibration signal is proposed, and the feasibility of this method is verified by comparing the practical effect of the newly constructed wavelet with other known wavelets in signal processing.

  12. Correlation-based temperature and emissivity separation algorithm

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on analyzing the relationship between the atmospheric downward radiance and surface emis- sivity, this paper proposes a correlation criterion to optimize surface temperature during the process of temperature and emissivity separation from thermal infrared hyperspectral data, and puts forward the correlation-based temperature and emissivity separation algorithm (CBTES). The algorithm uses the correlation between the atmospheric downward radiance and surface emissivity to optimize surface temperature, and obtains surface emissivity with this temperature. The accuracy of CBTES was evalu- ated by the simulated thermal infrared hyperspectral data. The simulated results show that the CBTES can achieve high accuracy of temperature and emissivity inversion. CBTES has been compared with the iterative spectrally smooth temperature/emissivity separation (ISSTES), and the comparison results show that they have relative accuracy. Besides, CBTES is insensitive to the instrumental random noise and the change of atmospheric downward radiance during the measurements. As regards the noniso- thermal pixel, its radiometric temperature changes slowly with the wavenumber when its emissivity is defined as r-emissivity. The CBTES can be used to derive the equivalent temperature of nonisothermal pixel in a narrow spectral region when we assumed that the radiometric temperature is invariable in the narrow spectral region. The derived equivalent temperatures in multi-spectral regions in 714―1250 cm?1 can characterize the change trend of nonisothermal pixel’s radiometric temperature.

  13. Correlation-based temperature and emissivity separation algorithm

    Institute of Scientific and Technical Information of China (English)

    CHENG Jie; LIU QinHuo; LI XiaoWen; XIAO Qing; LIU Qiang; DU YongMing

    2008-01-01

    Based on analyzing the relationship between the atmospheric downward radiance and surface emissivity, this paper proposes a correlation criterion to optimize surface temperature during the process of temperature and emissivity separation from thermal infrared hyperspectral data, and puts forward the correlation-based temperature and emissivity separation algorithm (CBTES). The algorithm uses the correlation between the atmospheric downward radiance and surface emissivity to optimize surface temperature, and obtains surface emissivity with this temperature. The accuracy of CBTES was evaluated by the simulated thermal infrared hyperspectral data. The simulated results show that the CBTES can achieve high accuracy of temperature and emissivity inversion. CBTES has been compared with the iterative spectrally smooth temperature/emissivity separation (ISSTES), and the comparison results show that they have relative accuracy. Besides, CBTES is insensitive to the instrumental random noise and the change of atmospheric downward radiance during the measurements. As regards the nonisothermal pixel, its radiometric temperature changes slowly with the wavenumber when its emissivity is defined as r-emissivity. The CBTES can be used to derive the equivalent temperature of nonisothermal pixel in a narrow spectral region when we assumed that the radiometric temperature is invariable in the narrow spectral region. The derived equivalent temperatures in multi-spectral regions in 714-250cm-1 can characterize the change trend of nonisothermal pixel's radiometric temperature.

  14. Graphene based integrated tandem supercapacitors fabricated directly on separators

    KAUST Repository

    Chen, Wei

    2015-04-09

    It is of great importance to fabricate integrated supercapacitors with extended operation voltages as high energy density storage devices. In this work, we develop a novel direct electrode deposition on separator (DEDS) process to fabricate graphene based integrated tandem supercapacitors for the first time. The DEDS process generates compact graphene-polyaniline electrodes directly on the separators to form integrated supercapacitors. The integrated graphene-polyaniline tandem supercapacitors demonstrate ultrahigh volumetric energy density of 52.5 Wh L^(−1) at power density of 6037 W L^(−1) and excellent gravimetric energy density of 26.1 Wh kg^(−1) at power density of 3002 W kg^(−1) with outstanding electrochemical stability for over 10000 cycles. This study show great promises for the future development of integrated energy storage devices.

  15. Separation of Doppler radar-based respiratory signatures.

    Science.gov (United States)

    Lee, Yee Siong; Pathirana, Pubudu N; Evans, Robin J; Steinfort, Christopher L

    2016-08-01

    Respiration detection using microwave Doppler radar has attracted significant interest primarily due to its unobtrusive form of measurement. With less preparation in comparison with attaching physical sensors on the body or wearing special clothing, Doppler radar for respiration detection and monitoring is particularly useful for long-term monitoring applications such as sleep studies (i.e. sleep apnoea, SIDS). However, motion artefacts and interference from multiple sources limit the widespread use and the scope of potential applications of this technique. Utilising the recent advances in independent component analysis (ICA) and multiple antenna configuration schemes, this work investigates the feasibility of decomposing respiratory signatures into each subject from the Doppler-based measurements. Experimental results demonstrated that FastICA is capable of separating two distinct respiratory signatures from two subjects adjacent to each other even in the presence of apnoea. In each test scenario, the separated respiratory patterns correlate closely to the reference respiration strap readings. The effectiveness of FastICA in dealing with the mixed Doppler radar respiration signals confirms its applicability in healthcare applications, especially in long-term home-based monitoring as it usually involves at least two people in the same environment (i.e. two people sleeping next to each other). Further, the use of FastICA to separate involuntary movements such as the arm swing from the respiratory signatures of a single subject was explored in a multiple antenna environment. The separated respiratory signal indeed demonstrated a high correlation with the measurements made by a respiratory strap used currently in clinical settings. PMID:26358241

  16. An Anderson-like model of the QCD chiral transition

    Science.gov (United States)

    Giordano, Matteo; Kovács, Tamás G.; Pittler, Ferenc

    2016-06-01

    We study the problems of chiral symmetry breaking and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We recast the staggered Dirac operator into an unconventional three-dimensional Anderson Hamiltonian ("Dirac-Anderson Hamiltonian") carrying internal degrees of freedom, with disorder provided by the fluctuations of the gauge links. In this framework, we identify the features relevant to chiral symmetry restoration and localisation of the low-lying Dirac eigenmodes in the ordering of the local Polyakov lines, and in the related correlation between spatial links across time slices, thus tying the two phenomena to the deconfinement transition. We then build a toy model based on QCD and on the Dirac-Anderson approach, replacing the Polyakov lines with spin variables and simplifying the dynamics of the spatial gauge links, but preserving the above-mentioned relevant dynamical features. Our toy model successfully reproduces the main features of the QCD spectrum and of the Dirac eigenmodes concerning chiral symmetry breaking and localisation, both in the ordered (deconfined) and disordered (confined) phases. Moreover, it allows us to study separately the roles played in the two phenomena by the diagonal and the off-diagonal terms of the Dirac-Anderson Hamiltonian. Our results support our expectation that chiral symmetry restoration and localisation of the low modes are closely related, and that both are triggered by the deconfinement transition.

  17. 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.

  18. Novel Lifshitz point for chiral transition in the magnetic field

    Directory of Open Access Journals (Sweden)

    Toshitaka Tatsumi

    2015-04-01

    Full Text Available Based on the generalized Ginzburg–Landau theory, chiral phase transition is discussed in the presence of magnetic field. Considering the chiral density wave we show that chiral anomaly gives rise to an inhomogeneous chiral phase for nonzero quark-number chemical potential. Novel Lifshitz point appears on the vanishing chemical potential line, which may be directly explored by the lattice QCD simulation.

  19. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.

  20. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG; XiaoMing

    2001-01-01

    Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.  ……

  1. Chiral doublet bands and energy-level crossing

    Institute of Scientific and Technical Information of China (English)

    QI Bin; MENG Jie; ZHANG Shuang-Quan; WANG Shou-Yu; PENG Jing

    2009-01-01

    Different definitions for chiral doublet bands based on excitation energies, B(E2) and B(M1) respectively are discussed in the triaxial particle rotor model. For the ideal chiral geometry, the selection rules of the electromagnetic transitions in different band definitions are illustrated. It is also shown that the energy-level crossings between chiral doublet bands may occur.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  3. Base-catalyzed depolymerization of lignin : separation of monomers

    Energy Technology Data Exchange (ETDEWEB)

    Vigneault, A. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering; Johnson, D.K. [National Renewable Energy Laboratory, Golden, CO (United States); Chornet, E. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering; National Renewable Energy Laboratory, Golden, CO (United States)

    2007-12-15

    Biofuels produced from residual lignocellulosic biomass range from ethanol to biodiesel. The use of lignin for the production of alternate biofuels and green chemicals has been studied with particular emphasis on the structure of lignin and its oxyaromatic nature. In an effort to fractionate lignocellulosic biomass and valorize specific constitutive fractions, the authors developed a strategy for the separation of 12 added value monomers produced during the hydrolytic base catalyzed depolymerization (BCD) of a Steam Exploded Aspen Lignin. The separation strategy was similar to vanillin purification to obtain pure monomers, but combining more steps after the lignin depolymerization such as acidification, batch liquid-liquid-extraction (LLE), followed by vacuum distillation, liquid chromatography (LC) and crystallization. The purpose was to develop basic data for an industrial size process flow diagram, and to evaluate both the monomer losses during the separation and the energy requirements. Experimentally testing of LLE, vacuum distillation and flash LC in the laboratory showed that batch vacuum distillation produced up to 4 fractions. Process simulation revealed that a series of 4 vacuum distillation columns could produce 5 distinct monomer streams, of which 3 require further chromatography and crystallization operations for purification. 22 refs., 4 tabs., 8 figs.

  4. Novel carbamoyl type quinine and quinidine based chiral anion exchangers implementing alkyne-azide cycloaddition immobilization chemistry.

    Science.gov (United States)

    Hettegger, Hubert; Kohout, Michal; Mimini, Vebi; Lindner, Wolfgang

    2014-04-11

    The synthesis and chromatographic evaluation of a series of new Cinchona derived chiral weak anion exchangers is presented. Huisgen Cu(I) mediated alkyne-azide cycloaddition, so-called click chemistry, was used as an immobilization strategy. In this way it was possible to immobilize about 90% of offered selector via 1,2,3-triazole linker, which displays a more efficient way of binding the selector to modified silica compared to common radical mediated thiol-ene addition. Problems associated with potential radical scavenging properties of chiral selectors thereby could be circumvented. The evaluation of the synthesized chiral stationary phases regarding chromatographic behavior was carried out using polar organic mode mobile phase composition and a set of representative chiral organic acids. Different loading densities revealed an optimum selector density of about 310μmol/g chiral stationary phase with respect to resolution and selectivity. A decrease of performance was observed for higher loading, indicating mutual spatial influence of selector units leading to sterical hindrance. In addition, we observed that the effect of free azide groups on retention is negligible and the overall chromatographic behavior is comparable to other Cinchona derived chiral stationary phases.

  5. Microscopic calculations based on chiral two- and three-nucleon forces for proton- and $^{4}$He-nucleus scattering

    CERN Document Server

    Toyokawa, Masakazu; Matsumoto, Takuma; Minomo, Kosho; Ogata, Kazuyuki; Kohno, Michio

    2015-01-01

    We investigate the effects of chiral three-nucleon force (3NF) on proton scattering at 65 MeV and $^{4}$He scattering at 72 MeV/nucleon from heavier targets, using the standard microscopic framework composed of the Brueckner-Hartree-Fock (BHF) method and the $g$-matrix folding model. For nuclear matter, the $g$ matrix is evaluated from chiral two-nucleon force (2NF) of N$^{3}$LO and chiral 3NF of NNLO by using the BHF method. Since the $g$ matrix thus obtained is numerical and nonlocal, an optimum local form is determined from the on-shell and near-on-shell components of $g$ matrix that are important for elastic scattering. For elastic scattering, the optical potentials are calculated by folding the local chiral $g$ matrix with projectile and target densities. This microscopic framework reproduces the experimental data without introducing any adjustable parameter. Chiral-3NF effects are small for proton scattering, but sizable for $^{4}$He scattering at middle angles where the data are available. Chiral 3NF, ...

  6. Hydrate-based heavy metal separation from aqueous solution

    Science.gov (United States)

    Song, Yongchen; Dong, Hongsheng; Yang, Lei; Yang, Mingjun; Li, Yanghui; Ling, Zheng; Zhao, Jiafei

    2016-02-01

    A novel hydrate-based method is proposed for separating heavy metal ions from aqueous solution. We report the first batch of experiments and removal characteristics in this paper, the effectiveness and feasibility of which are verified by Raman spectroscopy analysis and cross-experiment. 88.01-90.82% of removal efficiencies for Cr3+, Cu2+, Ni2+, and Zn2+ were obtained. Further study showed that higher R141b-effluent volume ratio contributed to higher enrichment factor and yield of dissociated water, while lower R141b-effluent volume ratio resulted in higher removal efficiency. This study provides insights into low-energy, intensive treatment of wastewater.

  7. Nitrogen Trifluoride-Based Fluoride- Volatility Separations Process: Initial Studies

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, Bruce K.; Scheele, Randall D.; Casella, Andrew M.; Kozelisky, Anne E.

    2011-09-28

    This document describes the results of our investigations on the potential use of nitrogen trifluoride as the fluorinating and oxidizing agent in fluoride volatility-based used nuclear fuel reprocessing. The conceptual process uses differences in reaction temperatures between nitrogen trifluoride and fuel constituents that produce volatile fluorides to achieve separations and recover valuable constituents. We provide results from our thermodynamic evaluations, thermo-analytical experiments, kinetic models, and provide a preliminary process flowsheet. The evaluations found that nitrogen trifluoride can effectively produce volatile fluorides at different temperatures dependent on the fuel constituent.

  8. Antibodies as Tailor-Made Chiral Selectors: an Interdisciplinary Approach to Enantiomer Separation and Detection%抗体作为特制的手性选择剂:一个跨学科的对映体分离和检测手段

    Institute of Scientific and Technical Information of China (English)

    HOFSTETTER Heike; HOFSTETTER Oliver

    2005-01-01

    It has long been known that the configurational isomers of biologically active compounds, e.g., nutrients, pesticides, and drugs, may exhibit different activities in a chiral environment such as the human body. Although the majority of drugs presently in development are chiral, analytical and preparative methods for the quantitative determination and purification of stereoisomers still lag behind. One reason is that commonly used chiral selectors for the direct resolution of enantiomers are not tailor-made for a specific analyte. The identification of suitable selectors for a particular pair of enantiomers still requires considerable experimentation and is generally demanding with regard to material, time and labor. The rational design of chiral host molecules, therefore, represents a challenge in facilitating enantiomer analysis. In this article, we describe how a combination of techniques ranging from organic synthesis to molecular biology yields antibodies of predetermined specificity and stereoselectivity that can be used as tailor-made chiral selectors for the chromatographic separation of enantiomers and their sensitive detection in immunosensors.

  9. Association of two single-isomer anionic CD in NACE for the chiral and achiral separation of fenbendazole, its sulphoxide and sulphone metabolites: application to their determination after in vitro metabolism.

    Science.gov (United States)

    Rousseau, Anne; Gillotin, Florian; Chiap, Patrice; Crommen, Jacques; Fillet, Marianne; Servais, Anne-Catherine

    2010-05-01

    A NACE method was developed for the separation of fenbendazole (FBZ), a prochiral drug giving rise to chiral (oxfendazole or OFZ) and nonchiral (FBZ sulphone or FBZSO(2)) metabolites. First, the effect of the nature and the concentration of CD as well as that of the acidic BGE on the enantiomeric separation of OFZ were studied. OFZ enantiomers were completely resolved using a BGE made up of 10 mM ammonium formate and 0.5 M TFA in methanol containing 10 mM heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-CD and 10 mM heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-CD. Moreover, the NACE method was found to be particularly well suited to the simultaneous determination of FBZ, OFZ enantiomers, and FBZSO(2). Thiabendazole was selected as an internal standard. The CD-NACE potential was then evaluated for in vitro metabolism studies using FBZ as a model case. The OFZ enantiomers and FBZSO(2) could be detected after incubation of FBZ in the phenobarbital-induced male rat liver microsomes systems.

  10. Comparison of coal separation characteristics based on different separating approaches in dry coal beneficiation flowsheet

    Institute of Scientific and Technical Information of China (English)

    HE Jing-feng; ZHAO Yue-min; HE Ya-qun; LUO Zhen-fu; DUAN Chen-long

    2015-01-01

    The separation characteristic of raw coal from Luoyang mining area, China, was investigated by applying a dry coal beneficiation flowsheet with the dense medium gas-solid fluidized bed as main separating equipment. The experimental and simulation results indicate that the dense medium gas-solid fluidized bed can provide uniform distribution and stable fluctuation of bed densities at various heights. Two types of different separating approaches were compared using the dry coal beneficiation flowsheet. Compared with obtaining cleaning coal in the first stage of the flowsheet, a higher yield of the cleaning coal and better separation efficiency can be achieved when discharging gangue in the first stage. Finally, the results indicate that 64.86% pure cleaning coal with an ash content of 11.77% and 13.53% middlings were obtained, and 21.61% gangue was removed in two successive separation stages with the probable errors of 0.05 and 0.07 g/cm3, respectively.

  11. Predictability of enantiomeric chromatographic behavior on various chiral stationary phases using typical reversed phase modeling software.

    Science.gov (United States)

    Wagdy, Hebatallah A; Hanafi, Rasha S; El-Nashar, Rasha M; Aboul-Enein, Hassan Y

    2013-09-01

    Pharmaceutical companies worldwide tend to apply chiral chromatographic separation techniques in their mass production strategy rather than asymmetric synthesis. The present work aims to investigate the predictability of chromatographic behavior of enantiomers using DryLab HPLC method development software, which is typically used to predict the effect of changing various chromatographic parameters on resolution in the reversed phase mode. Three different types of chiral stationary phases were tested for predictability: macrocyclic antibiotics-based columns (Chirobiotic V and T), polysaccharide-based chiral column (Chiralpak AD-RH), and protein-based chiral column (Ultron ES-OVM). Preliminary basic runs were implemented, then exported to DryLab after peak tracking was accomplished. Prediction of the effect of % organic mobile phase on separation was possible for separations on Chirobiotic V for several probes: racemic propranolol with 97.80% accuracy; mixture of racemates of propranolol and terbutaline sulphate, as well as, racemates of propranolol and salbutamol sulphate with average 90.46% accuracy for the effect of percent organic mobile phase and average 98.39% for the effect of pH; and racemic warfarin with 93.45% accuracy for the effect of percent organic mobile phase and average 99.64% for the effect of pH. It can be concluded that Chirobiotic V reversed phase retention mechanism follows the solvophobic theory. PMID:23775938

  12. Digital microfluidic magnetic separation for particle-based immunoassays.

    Science.gov (United States)

    Ng, Alphonsus H C; Choi, Kihwan; Luoma, Robert P; Robinson, John M; Wheeler, Aaron R

    2012-10-16

    We introduce a new format for particle-based immunoassays relying on digital microfluidics (DMF) and magnetic forces to separate and resuspend antibody-coated paramagnetic particles. In DMF, fluids are electrostatically controlled as discrete droplets (picoliters to microliters) on an array of insulated electrodes. By applying appropriate sequences of potentials to these electrodes, multiple droplets can be manipulated simultaneously and various droplet operations can be achieved using the same device design. This flexibility makes DMF well-suited for applications that require complex, multistep protocols such as immunoassays. Here, we report the first particle-based immunoassay on DMF without the aid of oil carrier fluid to enable droplet movement (i.e., droplets are surrounded by air instead of oil). This new format allowed the realization of a novel on-chip particle separation and resuspension method capable of removing greater than 90% of unbound reagents in one step. Using this technique, we developed methods for noncompetitive and competitive immunoassays, using thyroid stimulating hormone (TSH) and 17β-estradiol (E2) as model analytes, respectively. We show that, compared to conventional methods, the new DMF approach reported here reduced reagent volumes and analysis time by 100-fold and 10-fold, respectively, while retaining a level of analytical performance required for clinical screening. Thus, we propose that the new technique has great potential for eventual use in a fast, low-waste, and inexpensive instrument for the quantitative analysis of proteins and small molecules in low sample volumes. PMID:23013543

  13. Anomalous Chiral Superfluidity

    OpenAIRE

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

    2009-01-01

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

  14. Reducible chiral metamaterials

    CERN Document Server

    Ciattoni, Alessandro; Rizza, Carlo

    2016-01-01

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

  15. Complex-wave retrieval based on blind signal separation

    Institute of Scientific and Technical Information of China (English)

    Xiaodong Chai; Chengpeng Zhou; Zhaoyan Feng; Yinhua Wang; Yansheng Zuo

    2006-01-01

    In the process of the reconstruction of digital holography, the traditional methods of diffraction and filtration are commonly adopted to recover the original complex-wave signal. Influenced by twin-image and zero-order terms, the above-mentioned methods, however, either limit the field of vision or result in the loss of the amplitude and phase. A new method for complex-wave retrieval is presented, which is based on blind signal separation. Three frames of holograms are captured by a charge coupled device (CCD)camera to form an observation signal. The term containing only amplitude and phase of complex-wave is separated, by means of independent component analysis, from the observation signal, which effectively eliminates the zero-order term. Finally, the complex-wave retrieval of pure phase wavefront is achieved.Experimental results show that this method can better recover the amplitude and phase of the original complex-wave even when there is a frequency spectrum mixture in the hologram.

  16. Construction and NIR luminescent property of hetero-bimetallic Zn Nd complexes from two chiral salen-type Schiff-base ligands

    Science.gov (United States)

    Bi, Wei-Yu; Lü, Xing-Qiang; Chai, Wen-Li; Song, Ji-Rong; Wong, Wai-Yeung; Wong, Wai-Kwok; Jones, Richard A.

    2008-11-01

    Two new near-infrared (NIR) luminescent Zn-Nd complexes [ZnL 1Nd(OAc)(NO 3) 2] ( 3) and [ZnL 2Nd(DMF) 2(NO 3) 3] ( 4) have been obtained with two salen-type Schiff-base ligands H 2L 1 and H 2L 2, ( H 2L 1 = N, N'-bis(3-methoxysalicylidene)-(1s, 2s)-(-)1,2-dipheneylethylenediamine and H 2L 2 = N, N'-bis(3-methoxysalicylidene)-(s)-2,2-diamine-1,1'-binaphthyl) from the reaction of different chiral diamines with o-vanillin. The X-ray crystal structure analysis reveals that both of them crystallize in the chiral space groups with P2(1), a = 10.1669(6), b = 19.3775(11), c = 17.4639(10) Å, β = 94.8710(10)°, V = 3428.1(3) Å 3, Z = 4 for 3, and C2, a = 22.1914(13), b = 9.7886(6), c = 22.0138(13) Å, β = 118.9590(10)°, V = 4372.5(4) Å 3, Z = 4 for 4. Complexes 3- 4 are both dinuclear Zn-Nd structures, while suitable choice of chiral Schiff-base ligands could induce the different complexions of ligands and metal ions, and the functional control of ligand character shows a potentially effective way to the fine-tuning properties of NIR luminescence from Nd ions.

  17. Chiral Baryon with Quantized Pions

    CERN Document Server

    McNeil, J A

    1993-01-01

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

  18. Hadron Properties in a Chiral Quark-Sigma Model

    CERN Document Server

    Rashdan, M; El-Kholy, S; Abu-Shady, M

    2011-01-01

    Within a chiral quark sigma model in which quarks interact via the exchange of sigma and pi-mesons, hadron properties are investigated. This model of the nucleon and delta is based on the idea that strong QCD forces on very short distances (a small length scales 0.2- 1 fm) result in hidden chiral SU(2)xSU(2) symmetry and that there is a separation of roles between these forces which are responsible for binding quarks in hadrons and the forces which produce absolute confinement. We have solved the field equations in the mean field approximation for the hedgehog baryon state with different sets of model parameters. A new parametrization which well describe the nucleon properties has been introduced and compared with experimental data.

  19. Orientation-Dependent Handedness and Chiral Design

    Science.gov (United States)

    Efrati, Efi; Irvine, William T. M.

    2014-01-01

    Chirality occupies a central role in fields ranging from biological self-assembly to the design of optical metamaterials. The definition of chirality, as given by Lord Kelvin, associates chirality with the lack of mirror symmetry: the inability to superpose an object on its mirror image. While this definition has guided the classification of chiral objects for over a century, the quantification of handed phenomena based on this definition has proven elusive, if not impossible, as manifest in the paradox of chiral connectedness. In this work, we put forward a quantification scheme in which the handedness of an object depends on the direction in which it is viewed. While consistent with familiar chiral notions, such as the right-hand rule, this framework allows objects to be simultaneously right and left handed. We demonstrate this orientation dependence in three different systems—a biomimetic elastic bilayer, a chiral propeller, and optical metamaterial—and find quantitative agreement with chirality pseudotensors whose form we explicitly compute. The use of this approach resolves the existing paradoxes and naturally enables the design of handed metamaterials from symmetry principles.

  20. Carbon Nano tubes Based Mixed Matrix Membrane for Gas Separation

    International Nuclear Information System (INIS)

    Carbon nano tubes based mixed matrix membrane (MMM) was prepared by the solution casting method in which the functionalized multi walled carbon nano tubes (f-MWNTs) were embedded into the polyimide membrane and the resulting membranes were characterized. The effect of nominal MWNTs content between 0.5 and 1.0 wt % on the gas separation properties were looked into. The morphologies of the MMM also indicated that at 0.7 % loading of f- MWNTs, the structures of the MMM showed uniform finger-like structures which have facilitated the fast gas transport through the polymer matrix. It may also be concluded that addition of open ended and shortened MWNTs to the polymer matrix can improve its permeability by increasing diffusivity through the MWNTs smooth cavity. (author)

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

    Science.gov (United States)

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

    2015-02-01

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

  2. Baryons and Chiral Symmetry

    CERN Document Server

    Liu, Keh-Fei

    2016-01-01

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

  3. Chirality in Nonlinear Optics

    Science.gov (United States)

    Haupert, Levi M.; Simpson, Garth J.

    2009-05-01

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

  4. Chiral Rotational Spectroscopy

    CERN Document Server

    Cameron, Robert P; Barnett, Stephen M

    2015-01-01

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

  5. Cyclodextrin-Functionalized Monolithic Capillary Columns: Preparation and Chiral Applications.

    Science.gov (United States)

    Adly, Frady G; Antwi, Nana Yaa; Ghanem, Ashraf

    2016-02-01

    In this review, the recently reported approaches for the preparation of cyclodextrin-functionalized capillary monolithic columns are highlighted, with few applications in chiral separations using capillary liquid chromatography (CLC) and capillary electrochromatography (CEC). Chirality 28:97-109, 2016. © 2015 Wiley Periodicals, Inc.

  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. Chiral symmetry and chiral-symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E.

    1982-12-01

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

  8. Convenient Syntheses of Some C4 Chiral Building Blocks Starting From (S)-Malic Acid

    Institute of Scientific and Technical Information of China (English)

    WU TianJun; YU XianYong; ZHENG Xiao; HUANG PeiQiang

    2001-01-01

    @@ In the field of chiral technology, the synthesis of chiral intermediates and chiral building blocks occupies an important position. Chiral building blocks bearing double and / or multiple functionalities is particularly useful for the synthesis of chiral pharmaceuticals and chiral agrochemicals. In the recent years, we have been engaged in the development of synthetic methodology based on (S)-malic acid1-s. In these studies, malimide 2, easily accessible from (S)-malic acid, was shown to be a useful multifunctional building block in the asymmetric synthesis of natural products and chiral drugs (Scheme 1).

  9. Convenient Syntheses of Some C4 Chiral Building Blocks Starting From (S)-Malic Acid

    Institute of Scientific and Technical Information of China (English)

    WU; TianJun

    2001-01-01

    In the field of chiral technology, the synthesis of chiral intermediates and chiral building blocks occupies an important position. Chiral building blocks bearing double and / or multiple functionalities is particularly useful for the synthesis of chiral pharmaceuticals and chiral agrochemicals.  In the recent years, we have been engaged in the development of synthetic methodology based on (S)-malic acid1-s. In these studies, malimide 2, easily accessible from (S)-malic acid, was shown to be a useful multifunctional building block in the asymmetric synthesis of natural products and chiral drugs (Scheme 1).  ……

  10. Synthesis and applications of chiral metal-organic framework in the selective separation of enantiomers%手性金属有机骨架材料的合成及其在对映异构体选择性分离中的应用

    Institute of Scientific and Technical Information of China (English)

    祁晓月; 李先江; 白玉; 刘虎威

    2016-01-01

    手性现象在自然界中广泛存在,手性分离在药物研发、农用化学、药理学、环境科学和生物学等诸多领域具有重要意义。手性金属有机骨架化合物材料( MOFs)是一类具有特殊拓扑结构和可设计的孔道结构的新型多孔材料,加之其比表面积高、孔隙率大、热稳定性良好和溶剂耐受性好等特性,使得 MOFs 在分析化学领域的应用与研究日益深入。本文简要综述了手性 MOFs的合成方法,着重讨论了手性 MOFs在对映异构体选择性分离方面的应用及相关机理,最后对该类材料的发展前景做了展望。%Chirality is a universal phenomenon in nature. Chiral separation is vitally important in drug development,agricultural chemistry,pharmacology,environmental science,biology and many other fields. Chiral metal-organic frameworks( MOFs ) are a new group of porous materials with special topology and designable pore structures,as well as their high specific surface area,porosity,excellent thermal stability,solvent resistance,etc. Thus,chiral MOFs are promising with various applications in the field of analytical chemistry. This review summa-rizes the synthesis strategies of chiral MOFs and their applications in the selective separation of enantiomers,as well as related mechanism.

  11. Stage Separation Failure: Model Based Diagnostics and Prognostics

    Science.gov (United States)

    Luchinsky, Dmitry; Hafiychuk, Vasyl; Kulikov, Igor; Smelyanskiy, Vadim; Patterson-Hine, Ann; Hanson, John; Hill, Ashley

    2010-01-01

    Safety of the next-generation space flight vehicles requires development of an in-flight Failure Detection and Prognostic (FD&P) system. Development of such system is challenging task that involves analysis of many hard hitting engineering problems across the board. In this paper we report progress in the development of FD&P for the re-contact fault between upper stage nozzle and the inter-stage caused by the first stage and upper stage separation failure. A high-fidelity models and analytical estimations are applied to analyze the following sequence of events: (i) structural dynamics of the nozzle extension during the impact; (ii) structural stability of the deformed nozzle in the presence of the pressure and temperature loads induced by the hot gas flow during engine start up; and (iii) the fault induced thrust changes in the steady burning regime. The diagnostic is based on the measurements of the impact torque. The prognostic is based on the analysis of the correlation between the actuator signal and fault-induced changes in the nozzle structural stability and thrust.

  12. Advanced material separation technique based on dual energy CT scanning

    Science.gov (United States)

    Zamyatin, Alexander A.; Natarajan, Anusha; Zou, Yu

    2009-02-01

    We propose a method for material separation using dual energy data. Our method is suitable to separation of three or more materials. In this work we describe our method and show results of numerical simulation and with real dual-energy data of a head phantom. The proposed method of constructing the material separation map consists of the following steps: Data-domain dual energy decomposition - Vector plot - Density plot - Clustering - Color assignment. Density plots are introduced to allow automatic cluster separation. We use special image processing methods, including Gaussian decomposition, to improve the accuracy of material separation. We also propose using the HSL color model for better visualization and to bring a new dimension in material separation display. We study applications of bone removal and virtual contrast removal. Evaluation shows improved accuracy compared to standard methods.

  13. 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.

  14. The Chiral Magnetic Effect and Anomaly-Induced Transport

    CERN Document Server

    Kharzeev, Dmitri E

    2013-01-01

    The Chiral Magnetic Effect (CME) is the phenomenon of electric charge separation along the external magnetic field that is induced by the chirality imbalance. The CME is a macroscopic quantum effect - it is a manifestation of the chiral anomaly creating a collective motion in Dirac sea. Because the chirality imbalance is related to the global topology of gauge fields, the CME current is topologically protected and hence non-dissipative even in the presence of strong interactions. As a result, the CME and related quantum phenomena affect the hydrodynamical and transport behavior of systems possessing chiral fermions, from the quark-gluon plasma to chiral materials. The goal of the present review is to provide an elementary introduction into the main ideas underlying the physics of CME, a historical perspective, and a guide to the rapidly growing literature on this topic.

  15. Metallic and semiconducting carbon nanotubes separation using an aqueous two-phase separation technique: a review

    Science.gov (United States)

    Tang, Malcolm S. Y.; Ng, Eng-Poh; Juan, Joon Ching; Ooi, Chien Wei; Ling, Tau Chuan; Woon, Kai Lin; Loke Show, Pau

    2016-08-01

    It is known that carbon nanotubes show desirable physical and chemical properties with a wide array of potential applications. Nonetheless, their potential has been hampered by the difficulties in acquiring high purity, chiral-specific tubes. Considerable advancement has been made in terms of the purification of carbon nanotubes, for instance chemical oxidation, physical separation, and myriad combinations of physical and chemical methods. The aqueous two-phase separation technique has recently been demonstrated to be able to sort carbon nanotubes based on their chirality. The technique requires low cost polymers and salt, and is able to sort the tubes based on their diameter as well as metallicity. In this review, we aim to provide a review that could stimulate innovative thought on the progress of a carbon nanotubes sorting method using the aqueous two-phase separation method, and present possible future work and an outlook that could enhance the methodology.

  16. Understanding complex chiral plasmonics

    Science.gov (United States)

    Duan, Xiaoyang; Yue, Song; Liu, Na

    2015-10-01

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

  17. Preparation of molecularly imprinted resin based on chitosan for chiral recognition of S-mandelic acid.

    Science.gov (United States)

    Monier, M; El-Mekabaty, A

    2013-04-01

    An enantioselective S-mandelic acid (S-MA) imprinted chitosan (SMIC) was prepared by cross-linking of chitosan using formaldehyde cross-linker, in the presence of S-MA as an imprint template molecule and 0.5% acetic acid solution as a solvent. Non-imprinted cross-linked chitosan (NIC) as control was also prepared by the same procedure in absence of template molecules. The surface morphology of both SMIC and NIC were examined by scanning electron microscope (SEM). SMIC particles were applied to determine the optimum operational condition for S-MA separation from dilute aqueous solution. In adsorption step, optimum pH and retention time were 3.5 and 60 min, while corresponding values in extraction step were 1 and 40 min, respectively. Also, the adsorption isotherms indicated that the maximum adsorption capacities of S- and R-MA on SMIC were 100 ± 0.5 and 64 ± 0.8 mg/g, respectively, while in the case of NIC, both R- and S-MA present the same maximum adsorption. PMID:23357795

  18. Preparation of molecularly imprinted resin based on chitosan for chiral recognition of S-mandelic acid.

    Science.gov (United States)

    Monier, M; El-Mekabaty, A

    2013-04-01

    An enantioselective S-mandelic acid (S-MA) imprinted chitosan (SMIC) was prepared by cross-linking of chitosan using formaldehyde cross-linker, in the presence of S-MA as an imprint template molecule and 0.5% acetic acid solution as a solvent. Non-imprinted cross-linked chitosan (NIC) as control was also prepared by the same procedure in absence of template molecules. The surface morphology of both SMIC and NIC were examined by scanning electron microscope (SEM). SMIC particles were applied to determine the optimum operational condition for S-MA separation from dilute aqueous solution. In adsorption step, optimum pH and retention time were 3.5 and 60 min, while corresponding values in extraction step were 1 and 40 min, respectively. Also, the adsorption isotherms indicated that the maximum adsorption capacities of S- and R-MA on SMIC were 100 ± 0.5 and 64 ± 0.8 mg/g, respectively, while in the case of NIC, both R- and S-MA present the same maximum adsorption.

  19. Effects of gauge boson mass on chiral and deconfinement phase transitions in QED$_{3}$

    CERN Document Server

    Yin, Pei-Lin; Feng, Hong-Tao; Zong, Hong-Shi

    2016-01-01

    Based on the experimental observation that there is a coexisting region between the antiferromagnetic (AF) and $\\textit{d}$-wave superconducting ($\\textit{d}$SC) phases, the influences of gauge boson mass $m_{a}$ on chiral symmetry restoration and deconfinement phase transitions in QED$_{3}$ are investigated simultaneously within a unified framework, i.e., Dyson-Schwinger equations. The results show that the chiral symmetry restoration phase transition in the presence of the gauge boson mass $m_{a}$ is a typical second-order phase transition; the chiral symmetry restoration and deconfinement phase transitions are coincident; the critical number of fermion flavors $N^{c}_{f}$ decreases as the gauge boson mass $m_{a}$ increases and there exists a boundary that separates the $N^{c}_{f}$-$m_{a}$ plane into chiral symmetry breaking/confinement region for ($N_{f}^{c}$, $m_{a}$) below the boundary and chiral symmetry restoration/deconfinement region for ($N_{f}^{c}$, $m_{a}$) above it.

  20. Chiral fiber optical isolator

    Science.gov (United States)

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

    2009-02-01

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

  1. Separation of musical instruments based on amplitude and frequency comodulation

    Science.gov (United States)

    Jacobson, Barry D.; Cauwenberghs, Gert; Quatieri, Thomas F.

    2002-05-01

    In previous work, amplitude comodulation was investigated as a basis for monaural source separation. Amplitude comodulation refers to similarities in amplitude envelopes of individual spectral components emitted by particular types of sources. In many types of musical instruments, amplitudes of all resonant modes rise/fall, and start/stop together during the course of normal playing. We found that under certain well-defined conditions, a mixture of constant frequency, amplitude comodulated sources can unambiguously be decomposed into its constituents on the basis of these similarities. In this work, system performance was improved by relaxing the constant frequency requirement. String instruments, for example, which are normally played with vibrato, are both amplitude and frequency comodulated sources, and could not be properly tracked under the constant frequency assumption upon which our original algorithm was based. Frequency comodulation refers to similarities in frequency variations of individual harmonics emitted by these types of sources. The analytical difficulty is in defining a representation of the source which properly tracks frequency varying components. A simple, fixed filter bank can only track an individual spectral component for the duration in which it is within the passband of one of the filters. Alternatives are therefore explored which are amenable to real-time implementation.

  2. Enhanced Chiral Recognition by Cyclodextrin Dimers

    Directory of Open Access Journals (Sweden)

    Bart Jan Ravoo

    2011-07-01

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

  3. Chiral Superfluidity for QCD

    CERN Document Server

    Kalaydzhyan, Tigran

    2014-01-01

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

  4. Reasoning About Information Flow Security of Separation Kernels with Channel-based Communication

    OpenAIRE

    Zhao, Yongwang; Sann, David; Zhang, Fuyuan; Liu, Yang

    2015-01-01

    Assurance of information flow security by formal methods is mandated in security certification of separation kernels. As an industrial standard for separation kernels, ARINC 653 has been complied with by mainstream separation kernels. Security of functionalities defined in ARINC 653 is thus very important for the development and certification of separation kernels. This paper presents the first effort to formally specify and verify separation kernels with ARINC 653 channel-based communication...

  5. Towards a natural gesture interface: LDA-based gesture separability

    CERN Document Server

    Romaszewski, Michał; Głomb, Przemysław

    2011-01-01

    The goal of this paper is to analyse a method of validating a subset of gestures to be used as elements of a HCI interface. We investigate the applicability of LDA for gesture data dimensionality reduction. An Gesture mutual separability analysis of a diverse dataset of 22 natural gestures captured with two motion-capture devices is provided. Fisher criterion is used to produce measures of class separability and class overlap.

  6. Enantiomer separation of polychlorinated biphenyls on chiral chromatographic columns of cellulose and amylose by high-performance liquid chromatography%多氯联苯在纤维素和直链淀粉衍生物类手性色谱柱上的拆分

    Institute of Scientific and Technical Information of China (English)

    尹文华; 吴丞往; 方力; 张安平

    2012-01-01

    由于多氯联苯(Polychlorinated biphenyls)的纯对映体样品非常难得,国内外大多数的研究工作仅局限于外消旋体,而较少对其对映体的环境行为、生物毒性进行研究.采用三种不同的手性色谱柱对21种手性多氯联苯在不同流动相体系进行了拆分.最终有17种手性多氯联苯达到基线或部分分离,在纯正己烷流动相体系的拆分效果最佳.直链淀粉-三(5-氯-2-甲基苯基氨基甲酸酯)固定相具有很强的手性识别能力,Lux 3u Amylose-2柱可以作为Lux 3u Cellulose-1柱手性拆分的很好补充.当手性多氯联苯分子只含一个4号位氯代或同时含有5,5,号位氯代时,三种手性色谱柱较难对其分离完全.该方法分离速度快,可以作为纯对映体样品的制备方法.%Due to the enantiomer of polychlorinated biphenyls is rare, most of researches were focused on racemes, rather than environmental behavior or biotoxicity of enantiomer at home and abroad. The work investigated enantiomeric separation of 21 kinds of polychlorinated biphenyls with different chiral chromatographic columns by high-performance liquid chromatography. 17 kinds of PCBs achieved baseline or were at least partially separated. This was proved to be the most efficient for the chiral separation of 100% n-hexane mobile phase. As a kind of chiral stationary phases (CSPs), amylose tris (5-chlorine 2-methylphenylcarbamate) has a strong capacity of chiral recognition. Lux 3u Amylose-2 CSP is a great complementary for the chiral separation of Lux 3u Cellulose-1 CSP. The separations are difficult to be achieved for these three CSPs when polychlorinated biphenyls with chlorine substitution only in 4 position or in 5, 5' positions simultaneously. However, this approach could be used to obtain pure enantiomer of PCBs.

  7. Anomalous chiral superfluidity

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-02-08

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

  8. Chiral Shock Waves

    CERN Document Server

    Sen, Srimoyee

    2016-01-01

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

  9. A chiral photochromic Schiff base: (R)-4-meth­oxy-2-[(1-phenyl­ethyl)imino­meth­yl]phenol

    OpenAIRE

    Yukie Miura; Yoshikazu Aritake; Takashiro Akitsu

    2009-01-01

    The title chiral photochromic Schiff base compound, C16H17NO2, was synthesized from (R)-1-phenylethylamine and 5-methoxysalicylaldehyde. The molecule of the title compound exists in the phenol–imine tautomeric form. The dihedral angle between the two aromatic rings is 62.61 (11)°. An intramolecular O—H...N hydrogen bond with an O...N distance of 2.589 (2) Å is observed. The crystal packing is stabilized by C—H...&am...

  10. Doped Chiral Polymer Metamaterials Project

    Data.gov (United States)

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

  11. Grand unification and proton stability based on a chiral SU(8) theory

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, N.G.; Mannheim, P.D.

    1980-06-01

    A grand-unified model of the strong, electromagnetic, and weak interactions is presented based on a local SU(8)/sub L/ X SU(8)/sub R/ gauge theory that possesses a global U(8)/sub L/ X U(8)/sub R/ invariance. The model is spontaneously broken by the recently introduced neutrino pairing mechanism, in which a Higgs field that transforms like a pair of right-handed neutrinos acquires a vacuum expectation value. This neutrino pairing breaks the model down to the standard Weinberg-Salam phenomenology. Further, the neutrino pairing causes the two initial global currents of the model, fermion number and axial fermion number, to mix with the non-Abelian local currents to leave unbroken two new global currents, namely, baryon number and a particular lepton number that counts charged leptons and left-handed neutrinos only. The exact conservations of these two resulting currents ensure the absolute stability of the proton, the masslessness of the observed left-handed neutrinos, and the standard lepton number conservation of the usual weak interactions. A further feature of the model is the simultaneous absence of both strong CP violations and of observable axions. The model has a testable prediction, namely, the existence of an absolutely stable, relatively light, massive neutral lepton generated entirely from the right-handed neutrino sector of the theory. 1 table.

  12. A method based on a separation of variables in magnetohydrodynamics (MHD); Une methode de separation des variables en magnetohydrodynamique

    Energy Technology Data Exchange (ETDEWEB)

    Cessenat, M.; Genta, P.

    1996-12-31

    We use a method based on a separation of variables for solving a system of first order partial differential equations, in a very simple modelling of MHD. The method consists in introducing three unknown variables {phi}1, {phi}2, {phi}3 in addition of the time variable {tau} and then searching a solution which is separated with respect to {phi}1 and {tau} only. This is allowed by a very simple relation, called a `metric separation equation`, which governs the type of solutions with respect to time. The families of solutions for the system of equations thus obtained, correspond to a radial evolution of the fluid. Solving the MHD equations is then reduced to find the transverse component H{sub {Sigma}} of the magnetic field on the unit sphere {Sigma} by solving a non linear partial differential equation on {Sigma}. Thus we generalize ideas due to Courant-Friedrichs and to Sedov on dimensional analysis and self-similar solutions. (authors).

  13. Particle Residence Time in Column Flotation Based on Cyclonic Separation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-hua; LIU Jiong-tian

    2007-01-01

    The cyclonic static micro-bubble column flotation (FCSMC) is an effective separation device for fine particle treatment. The high mineralization rate and short flotation time of this equipment can be attributed to its unique cyclonic force field. It also has been observed that the presence of a cyclonic force field leads to a lower bottom separation size limit and a reduction of unselective entrainment. The collection zone of the column is considered to consist of two parts, a column separation zone and a cyclonic zone. Total recovery of the collection zone was developed. For our study, we analyzed the particle movement in the cyclonic zone. Particle residence time equations for the cyclonic zone were derived by force analysis. Results obtained in this study provide a theoretical foundation for the design and scale-up of the FCSMC.

  14. Blind source separation based on generalized gaussian model

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; KONG Wei; ZHOU Yue

    2007-01-01

    Since in most blind source separation (BSS) algorithms the estimations of probability density function (pdf) of sources are fixed or can only switch between one sup-Gaussian and other sub-Gaussian model,they may not be efficient to separate sources with different distributions. So to solve the problem of pdf mismatch and the separation of hybrid mixture in BSS, the generalized Gaussian model (GGM) is introduced to model the pdf of the sources since it can provide a general structure of univariate distributions. Its great advantage is that only one parameter needs to be determined in modeling the pdf of different sources, so it is less complex than Gaussian mixture model. By using maximum likelihood (ML) approach, the convergence of the proposed algorithm is improved. The computer simulations show that it is more efficient and valid than conventional methods with fixed pdf estimation.

  15. Prospects of Source-Separation-Based Sanitation Concepts: A Model-Based Study

    Directory of Open Access Journals (Sweden)

    Cees Buisman

    2013-07-01

    Full Text Available Separation of different domestic wastewater streams and targeted on-site treatment for resource recovery has been recognized as one of the most promising sanitation concepts to re-establish the balance in carbon, nutrient and water cycles. In this study a model was developed based on literature data to compare energy and water balance, nutrient recovery, chemical use, effluent quality and land area requirement in four different sanitation concepts: (1 centralized; (2 centralized with source-separation of urine; (3 source-separation of black water, kitchen refuse and grey water; and (4 source-separation of urine, feces, kitchen refuse and grey water. The highest primary energy consumption of 914 MJ/capita(cap/year was attained within the centralized sanitation concept, and the lowest primary energy consumption of 437 MJ/cap/year was attained within source-separation of urine, feces, kitchen refuse and grey water. Grey water bio-flocculation and subsequent grey water sludge co-digestion decreased the primary energy consumption, but was not energetically favorable to couple with grey water effluent reuse. Source-separation of urine improved the energy balance, nutrient recovery and effluent quality, but required larger land area and higher chemical use in the centralized concept.

  16. Environmental Consequences of Future Biogas Technologies based on Separated Slurry

    DEFF Research Database (Denmark)

    Hamelin, Lorie; Wesnæs, Marianne; Wenzel, Henrik;

    2011-01-01

    the volatile solids in the solid fraction. The biogas scenario involving the most efficient separation technology resulted in a dry matter separation efficiency of 87% and allowed a net reduction of the global warming potential of 40%, compared to the reference slurry management. This figure comprises...... the whole slurry life cycle, including the flows bypassing the biogas plant. This study includes soil carbon balances and a method for quantifying the changes in yield resulting from increased nitrogen availability as well as for quantifying mineral fertilizers displacement. Soil carbon balances showed...

  17. Chiral geometry in multiple chiral doublet bands

    Science.gov (United States)

    Zhang, Hao; Chen, Qibo

    2016-02-01

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

  18. Prospects of Source-Separation-Based Sanitation Concepts: A Model-Based Study

    NARCIS (Netherlands)

    Tervahauta, T.H.; Trang Hoang,; Hernández, L.; Zeeman, G.; Buisman, C.J.N.

    2013-01-01

    Separation of different domestic wastewater streams and targeted on-site treatment for resource recovery has been recognized as one of the most promising sanitation concepts to re-establish the balance in carbon, nutrient and water cycles. In this study a model was developed based on literature data

  19. Chiral Cyclobutane β-Amino Acid-Based Amphiphiles: Influence of Cis/Trans Stereochemistry on Solution Self-Aggregation and Recognition.

    Science.gov (United States)

    Sorrenti, Alessandro; Illa, Ona; Pons, Ramon; Ortuño, Rosa M

    2015-09-01

    Novel diastereomeric anionic amphiphiles based on the rigid cyclobutane β-amino acid scaffold have been synthesized and deeply investigated with the aim of generating new functional supramolecular architectures on the basis of the rational design of original amphiphilic molecules and the control of their self-assembly. The main interest has been focused on the effect that cis/trans stereochemistry exerts on their molecular organization and recognition. In diluted solutions, the relative stereochemistry mainly influences the headgroup solvation and anionic-charge stabilization, i.e., better stabilized in the cis diastereoisomer due to intramolecular hydrogen-bonding and/or charge-dipole interactions. This provokes differences in their physicochemical behavior (pKa, cmc, conductivity) as well as in the structural parameters of the spherical micelles formed. Although both diastereoisomers form fibers that evolve with time from the spherical micelles, they display markedly different morphology and kinetics of formation. In the lyotropic liquid crystal domain, the greatest differences are observed at the highest concentrations and can be ascribed to different hydrogen-bonding and molecular packing imposed by the stereochemical constraints. Remarkably, the spherical micelles of the two anionic surfactants show dramatically diverse enantioselection ability for bilirubin enantiomers. In addition, both the surfactants form heteroaggregates with bilirubin at submicellar concentrations but with a different expression of supramolecular chirality. This points out that the unlike relative configuration of the two surfactants influences their chiral recognition ability as well as the fashion in which chirality is expressed at the supramolecular level by controlling the molecular organization in both micellar aggregates and surfactant/bilirubin heteroaggregates. All these differential features can be appropriate and useful for the design and development of new soft materials with

  20. Wormholes from Chiral Fields

    International Nuclear Information System (INIS)

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

  1. Spectral signatures of chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

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

  2. Carbon nanotube-based separation columns for microchip electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, K. B.; Delacourt, B.; Kutter, Jörg P.

    2015-01-01

    Fabrication of the stationary phase for microchip chromatography is most often done by packing of the individual separation channel after fabrication of the microfluidic chip, which is a very time-consuming and costly process (Kutter. J Chromatogr A 1221:72–82, 2012). Here, we describe in detail...

  3. Carbon Nanotube-Based Separation Columns for Microchip Electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Delacourt, B.; Kutter, Jörg Peter

    2015-01-01

    Fabrication of the stationary phase for microchip chromatography is most often done by packing of the individual separation channel after fabrication of the microfluidic chip, which is a very time-consuming and costly process (Kutter. J Chromatogr A 1221:72–82, 2012). Here, we describe in detail...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  6. Chiral Magnetic "Superfluidity"

    CERN Document Server

    Sadofyev, Andrey V

    2015-01-01

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

  7. Chiral Magnetic Effect and Chiral Phase Transition

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  8. Bacteriophage-based nanoprobes for rapid bacteria separation

    Science.gov (United States)

    Chen, Juhong; Duncan, Bradley; Wang, Ziyuan; Wang, Li-Sheng; Rotello, Vincent M.; Nugen, Sam R.

    2015-10-01

    The lack of practical methods for bacterial separation remains a hindrance for the low-cost and successful development of rapid detection methods from complex samples. Antibody-tagged magnetic particles are commonly used to pull analytes from a liquid sample. While this method is well-established, improvements in capture efficiencies would result in an increase of the overall detection assay performance. Bacteriophages represent a low-cost and more consistent biorecognition element as compared to antibodies. We have developed nanoscale bacteriophage-tagged magnetic probes, where T7 bacteriophages were bound to magnetic nanoparticles. The nanoprobe allowed the specific recognition and attachment to E. coli cells. The phage magnetic nanprobes were directly compared to antibody-conjugated magnetic nanoprobes. The capture efficiencies of bacteriophages and antibodies on nanoparticles for the separation of E. coli K12 at varying concentrations were determined. The results indicated a similar bacteria capture efficiency between the two nanoprobes.The lack of practical methods for bacterial separation remains a hindrance for the low-cost and successful development of rapid detection methods from complex samples. Antibody-tagged magnetic particles are commonly used to pull analytes from a liquid sample. While this method is well-established, improvements in capture efficiencies would result in an increase of the overall detection assay performance. Bacteriophages represent a low-cost and more consistent biorecognition element as compared to antibodies. We have developed nanoscale bacteriophage-tagged magnetic probes, where T7 bacteriophages were bound to magnetic nanoparticles. The nanoprobe allowed the specific recognition and attachment to E. coli cells. The phage magnetic nanprobes were directly compared to antibody-conjugated magnetic nanoprobes. The capture efficiencies of bacteriophages and antibodies on nanoparticles for the separation of E. coli K12 at varying

  9. Wind-Induced Ventilation Based on the Separated Flow Region

    Directory of Open Access Journals (Sweden)

    Mostafa Rahimi

    2016-01-01

    Full Text Available An experimental investigation was conducted to study the potential use of the pressure reduction within the separated flow region followed by the wake at the leeward direction of a solid surface in natural ventilation of buildings. Air flow with mean velocity up to 7 m/s was directed onto a solid surface (circular plate and a semi-spherical surface behind which the top end of a vertical vent pipe had been placed. Pressure reduction at the exit section of the pipe, which was well inside the separated flow region, induced an air flow within the pipe. This air flow rate from the stagnant surroundings into the wake region was measured under different geometrical configurations and for various wind velocities. The study revealed that the pressure reduction within the separated flow region would be applicable for natural ventilation of different spaces at least as an auxiliary system. The spaces include; sanitary places, crop protection stocks, industrial workshops and other spaces where no regular ventilation is required.

  10. Rapid Separation of Disconnected Triangle Meshes Based on Graph Traversal

    Energy Technology Data Exchange (ETDEWEB)

    Ji, S J; Wang, Y [Department of Mechanical Manufacturing and Automation, Harbin Institute of Technology, Harbin, 150001 (China)

    2006-10-15

    In recent year, The STL file become a de facto standard on the file presentation in CAD/CAM, computer graph and reverse engineering. When point cloud which is obtained by scanning object body using optical instrument is used to reconstruct an original model, the points cloud is presented by the STL file. Usually, datum of several separated and relative objects are stored in a single STL file, when such a file is operated by a computer, the datum in the file is firstly separated and then each element of every triangle pitch on the triangle mesh is traversed and visited and is calculated. The problem is analyzed and studied by many experts, but there is still a lack of a simple and quick algorithm. An algorithm which uses graph traversal to traverse each element of the triangle meshes and separate several disconnected triangle meshes is presented by the paper, the searching and calculating speed of the data on the triangle meshes is enhanced, memory size of the computer is reduced, complexity of the data structure is simplified and powerful guarantee is made for the next process by using this algorithm.

  11. Separation of single-walled carbon nanotubes by gel-based chromatography using surfactant step-gradient techniques and development of new instrumentation for studying SWCNT reaction processes

    Science.gov (United States)

    Breindel, Leonard M.

    Single-walled carbon nanotube (SWCNT) synthesis methods such as CoMoCATTM, HiPcoTM, pulsed laser vaporization (PLV), and catalytic chemical vapor deposition (CCVD) produce several different distributions of (n,m) SWCNT structures, where ( n,m) defines the nanotube diameter and chiral wrapping angle. Post-synthesis processing such as functionalization and/or separations must therefore be employed to yield high purity electronic or single (n,m) samples. Through the use of a surfactant gradient across a gel-based chromatographic column, separations of single (n,m) species can be achieved. Anionic surfactants such as SDS, SDBS, and AOT display different separation effectiveness for single (n,m) species. Results of near-infrared optical absorption for separated SWCNT surfactant suspensions will be discussed, leading to a broader understanding of the important factors necessary for the gel chromatography separation technique. In particular, the effects of SWCNT/surfactant micelle structure are found to be key to achieving fast, simple SWCNT electronic type separations. Additionally, development of new instrumentation for the near-infrared spectrofluorimetric analysis (NIR-SFA) of SWCNTs is useful to the advancement of fundamental SWCNT research and applications. NIR-SFA, for instance, allows for the (n,m) structures of a sample to be identified and monitored during the progress of a chemical reaction or separation experiment. Seeking to achieve the time resolutions necessary for such experiments, the design and optimizations of a system utilizing single-wavelength excitation by diode lasers coupled with a fast NIR detection system are presented.

  12. Synthesis and structural characterization of a new chiral porous hybrid organic–inorganic material based on γ-zirconium phosphates and L-(+)-phosphoserine

    Energy Technology Data Exchange (ETDEWEB)

    Alhendawi, Hussein M.H., E-mail: hussein.alhendawi@yahoo.com [Department of Chemistry, Faculty of Science, Al-Azhar University of Gaza, 1277 Gaza, Palestine (Country Unknown)

    2013-05-01

    In the present work, a chiral layered derivative of γ-zirconium phosphate (γ-ZrP) containing L-(+)-phosphoserine (γ-ZrP-PS*) covalently attached to inorganic layers has been prepared by means of topotactic exchange reaction. This organic–inorganic derivative is characterized by X-ray diffractometry, Solid {sup 13}C–NMR and FT-IR spectrophotometries and thermal analyses. A maximum level of topotactic replacement of 20% is achieved. Under both the acidic environment of the interlayer region of γ-ZrP and the acidic synthesis conditions, the hydrolysis of the ester bond of PS* is expected to take place to some extent. For this reason, it was impossible to exceed the recent percentage, which in turn reflects the relative moderate stability of the above mentioned bond under these conditions. In order to be more certain with regard to an expected further hydrolysis for this bond after separation, a sample of γ-ZrP-PS* was stored in a desiccator over a saturated solution of BaCl{sub 2} (90% relative humidity) for three months, and then the sample re-analyzed once again. Surprisingly, the results show that the sample still keeps almost the same level of exchange (i.e., 20%). Second, it is revealed that the sample almost gives the same spectroscopic and thermal behavior. This could be attributed to the less acidic character of the partially exchanged inorganic layers of the sample in comparison with that of the precursor γ-ZrP. Therefore, the PS* molecules persist and stay there into the interlayer gallery without further hydrolysis. - Graphical abstract: • Red: oxygen • White: zirconium • Cyan: carbon • Yellow: phosphorus • Blue: nitrogen. Highlights: • L-(+)-Phosphoserine (PS*) is exchanged with γ-ZrP by means of topotactic exchange. • The maximum exchange level is 20%. • γ-ZrP is functionalized with chiral amino acid group. • γ-ZrP-PS* has large chiral space for huge guest molecules to be intercalated.

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

    Directory of Open Access Journals (Sweden)

    Eckart Marsch

    2015-04-01

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

  14. Fe-Ti-O based catalyst for large-chiral-angle single-walled carbon nanotube growth

    DEFF Research Database (Denmark)

    He, Maoshuai; Zhang, Lili; Jiang, Hua;

    2016-01-01

    Catalyst selection is very crucial for controlled growth of single-walled carbon nanotubes (SWNTs). Here we introduce a well-designed Fe-Ti-O solid solution for SWNT growth with a high preference to large chiral angles. The Fe-Ti-O catalyst was prepared by combining Ti layer deposition onto premade...... Fe nanoparticles with subsequent high-temperature air calcination, which favours the formation of a homogeneous Fe-Ti-O solid solution. Using CO as the carbon feedstock, chemical vapour deposition growth of SWNTs at 800 °C was demonstrated on the Fe-Ti-O catalyst. Nanobeam electron diffraction...

  15. Hypernucleus-16O in the density-dependent Hartree approach based on the chiral-σ model

    International Nuclear Information System (INIS)

    A relativistic density-dependent interaction has been used to study hypernucleus 16O. The density-dependent coupling constants of the relativistic effective Hartree-Lagrangian are obtained from the relativistic Brueckner-Bethe-Goldstone results of nuclear matter in the chiral-σ model. With these density-dependent coupling constants, the bound states and the single-particle energy spectra of the hypernuclei Λ16O and Σ16O are obtained. The theoretical results of Λ16O are in agreement with the experimental data fairly well

  16. Preparation and thermo-optical characteristics of a smart polymer-stabilized liquid crystal thin film based on smectic A–chiral nematic phase transition

    International Nuclear Information System (INIS)

    A smart polymer stabilized liquid crystal (PSLC) thin film with temperature-controllable light transmittance was prepared based on a smectic-A (SmA)–chiral nematic (N*) phase transition, and then the effect of the composition and the preparation condition of the PSLC film on its thermo-optical (T-O) characteristics has been investigated in detail. Within the temperature range of the SmA phase, the PSLC shows a strong opaque state due to the focal conic alignment of liquid crystal (LC) molecules, while the film exhibits a transparent state result from the parallel alignment of N* phase LC molecules at a higher temperature. Importantly, the PSLC films with different temperature of phase transition and contrast ratio can be prepared by changing the composition of photo-polymerizable monomer/LC/chiral dopant. According to the competition between the polymerization of the curable monomers and the diffusion of LC molecules, the ultraviolet (UV) curing surrounding temperature and the intensity of UV irradiation play a critical role in tuning the size of the polymer network meshes, which in turn influence the contrast ratio and the switching speed of the film. Our observations are expected to pave the way for preparing smart PSLC thin films for applications in areas of smart windows, thermo-detectors and other information recording devices. (paper)

  17. Preparation and evaluation of monodispersed, submicron, non-porous silica particles functionalized with β-CD derivatives for chiral-pressurized capillary electrochromatography.

    Science.gov (United States)

    Yangfang, Lu; Hui, Wang; Yun, Xue; Xue, Gu; Yan, Wang; Chao, Yan

    2015-09-01

    Submicron, non-porous, chiral silica stationary phase has been prepared by the immobilization of functionalized β-CD derivatives to isocyanate-modified silica via chemical reaction and applied to the pressurized capillary electrochromatography (pCEC) enantio-separation of various chiral compounds. The submicron, non-porous, cyclodextrin-based chiral stationary phases (sub_μm-CSP2) exhibited excellent chiral recognition of a wide range of analytes including clenbuterol hydrochloride, mexiletine hydrochloride, chlorpheniramine maleate, esmolol hydrochloride, and metoprolol tartrate. The synthesized submicron particles were regularly spherical and uniformly non-porous with an average diameter of around 800 nm and a mean pore size of less than 2 nm. The synthesized chiral stationary phase was packed into 10 cm × 100 μm id capillary columns. The sub_μm-CSP2 column used in the pCEC system showed better separation of the racemates and at a higher rate compared to those used in the capillary liquid chromatography mode (cLC) system. The sub_μm-CSP2 possessed high mechanical strength, high stereoselectivity, and long lifespan, demonstrating rapid enantio-separation and good resolution of samples. The column provided an efficiency of up to 170,000 plates/m for n-propylbenzene. PMID:25990895

  18. Applications of chiral symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, R.D.

    1995-03-01

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

  19. Development of chiral sulfoxide ligands for asymmetric catalysis.

    Science.gov (United States)

    Trost, Barry M; Rao, Meera

    2015-04-20

    Nitrogen-, phosphorus-, and oxygen-based ligands with chiral backbones have been the historic workhorses of asymmetric transition-metal-catalyzed reactions. On the contrary, sulfoxides containing chirality at the sulfur atom have mainly been used as chiral auxiliaries for diastereoselective reactions. Despite several distinct advantages over traditional ligand scaffolds, such as the proximity of the chiral information to the metal center and the ability to switch between S and O coordination, these compounds have only recently emerged as a versatile class of chiral ligands. In this Review, we detail the history of the development of chiral sulfoxide ligands for asymmetric catalysis. We also provide brief descriptions of metal-sulfoxide bonding and strategies for the synthesis of enantiopure sulfoxides. Finally, insights into the future development of this underutilized ligand class are discussed.

  20. Enhanced Electromagnetic Chirality by Locally Excited Surface Plasmon Polaritons

    CERN Document Server

    Alizadeh, M H

    2015-01-01

    The possibility to enhance chiral light-matter interactions through plasmonic nanostructures provides entirely new opportunities for greatly improving the detection limits of chiroptical spectroscopies down to the single molecule level. The most pronounced of these chiral interactions occur in the ultraviolet (UV) range of the electromagnetic spectrum, which is difficult to access with conventional localized plasmon resonance based sensors. Although Surface Plasmon Polaritons (SPPs) on noble metal films can sustain resonances in the desired spectral range, their transverse magnetic nature has been an obstacle for enhancing chiroptical effects. Here we demonstrate, both analytically and numerically, that SPPs excited by near-field sources can exhibit rich and non-trivial chiral characteristics. In particular, we show that the excitation of SPPs by a chiral source not only results in a locally enhanced optical chirality but also achieves manifold enhancement of net optical chirality. Our finding that SPPs facil...

  1. 手性溶剂萃取分离顺式二氯菊酸对映体%Separation of cis-Permethrinic Acid Enantiomers by Chiral Extraction with Hydrophobic Tartaric Esters

    Institute of Scientific and Technical Information of China (English)

    易健民; 陈立根; 唐课文; 潘春跃; 黄可龙

    2008-01-01

      研究了顺式二氯菊酸(cis-PA)对映体在含有酒石酸酯手性选择体的水-1,2-二氯乙烷两相溶液中的萃取分配行为,考察了有机相种类、L-酒石酸酯浓度、水相pH、L-酒石酸酯烷基链长度和萃取温度等因素对萃取分离效果的影响。结果表明,L-酒石酸酯与Ⅱ对映体形成的复合物稳定性比与Ⅰ对映体形成的复合物要好;1,2-二氯乙烷作为有机相效果较好;随着L-酒石酸酯浓度的增大,分配系数K逐渐增大,而分离因子α先增大然后开始减小;随着pH的增大,K和α都降低;L-酒石酸酯烷基链长度及萃取温度对K和α有较大影响。%  The distribution of cis-permethrinic acid enantiomers was examined in aqueous solution and 1,2-dichloroethane organic solvent containing chiral selector hydrophobic L-tartaric esters. The influences of organic solvents, the concentration of L-tartaric esters, pH, the length of alkyl chain of L-tartaric esters and temperature on the partition coefficient(K) and separation factor(α) was investigated. The results showed, L-tartaric esters formed more stable complex with Ⅱ-cis-PA than that of Ⅰ-cis-PA. The performance of the four kinds of organic solvents is different, 1,2-dichloroethane was better than the others. With increasing concentration of L-tartaric esters, K increased, butαincreased firstly and then decreased. With the increasing of pH, K andαdecreased. The length of alkyl chain of L-tartaric ester and the temperature had a great influence on K andα.

  2. Chiral symmetry in hadron physics methods and ideas of chiral symmetry

    International Nuclear Information System (INIS)

    Methods and ideas of chiral symmetry is presented based on a lecture note to help the future researches in hadron dynamics along with the chiral symmetry. The chiral symmetry was originally developed as the symmetry between currents before the discovery of QCD. It has come to be understood in principle by now that the symmetry is spontaneously broken and only the part of flavor symmetry remains explicitly. In QCD, however, the chiral symmetry has come to be regarded as the base of the symmetry of the global flavor space of quarks. One of the recent topics of the lattice gauge theory is how the hadron properties will change when the broken symmetry is going to be restored. Since the chiral symmetry is global, it is different from gauge symmetry which is local. It explains the degeneracy of hadron masses and relations between the elements of S-matrix in which same number of particles are included. In practice, however, the symmetry of the axial part is spontaneously broken and pions which behave like gauge particles come to play. Chiral symmetry is defined as the (internal) flavor symmetry for the two independent chirality states of quarks. It discriminates two different fundamental quarks defined for the Lorentz groups O(4) - SL(2, C). The symmetry transformation itself is, however, different from the chirality. They should not be confused. In this lecture note, fundamental properties of pions are described on the basis of the interaction with nucleons at first. General properties of the chiral symmetry and some of the low energy theorems on current algebra are introduced. Then, linear sigma model and nonlinear sigma model are introduced. Then the Skyrme-model, which provides an idea as important as quarks, is explained. One of the interesting topics at present is to restore the broken axial symmetry experimentally to investigate the mechanism of symmetry breaking. (S. Funahashi)

  3. The covariant chiral ring

    Science.gov (United States)

    Bourget, Antoine; Troost, Jan

    2016-03-01

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

  4. The Covariant Chiral Ring

    CERN Document Server

    Bourget, Antoine

    2015-01-01

    We construct a covariant generating function for the spectrum of chiral primaries of symmetric orbifold conformal field theories with N=(4,4) supersymmetry in two dimensions. For seed target spaces K3 and T4, the generating functions capture the SO(21) and SO(5) representation theoretic content of the chiral ring respectively. Via string dualities, we relate the transformation properties of the chiral ring under these isometries of the moduli space to the Lorentz covariance of perturbative string partition functions in flat space.

  5. Chiral nucleon-nucleon forces in nuclear structure calculations

    Directory of Open Access Journals (Sweden)

    Coraggio L.

    2016-01-01

    Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.

  6. Chiral nucleon-nucleon forces in nuclear structure calculations

    CERN Document Server

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

    2016-01-01

    Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.

  7. Synthesis and applications of novel bis(ammonium) chiral ionic liquids derived from isomannide

    DEFF Research Database (Denmark)

    Kumar, Vineet; Olsen, Carl Erik; Schäffer, Susan J.;

    2007-01-01

    Carbohydrate-based novel bis(ammonium) chiral ionic liquids have been synthesized by following a straightforward protocol using isomannide as the substrate. Their applications in chiral discrimination and optical resolution of racemates have been established.......Carbohydrate-based novel bis(ammonium) chiral ionic liquids have been synthesized by following a straightforward protocol using isomannide as the substrate. Their applications in chiral discrimination and optical resolution of racemates have been established....

  8. Chiral selection and frequency response of spiral waves in reaction-diffusion systems under a chiral electric field

    Science.gov (United States)

    Li, Bing-Wei; Cai, Mei-Chun; Zhang, Hong; Panfilov, Alexander V.; Dierckx, Hans

    2014-05-01

    Chirality is one of the most fundamental properties of many physical, chemical, and biological systems. However, the mechanisms underlying the onset and control of chiral symmetry are largely understudied. We investigate possibility of chirality control in a chemical excitable system (the Belousov-Zhabotinsky reaction) by application of a chiral (rotating) electric field using the Oregonator model. We find that unlike previous findings, we can achieve the chirality control not only in the field rotation direction, but also opposite to it, depending on the field rotation frequency. To unravel the mechanism, we further develop a comprehensive theory of frequency synchronization based on the response function approach. We find that this problem can be described by the Adler equation and show phase-locking phenomena, known as the Arnold tongue. Our theoretical predictions are in good quantitative agreement with the numerical simulations and provide a solid basis for chirality control in excitable media.

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

    CERN Document Server

    Braguta, V V

    2016-01-01

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

  10. A resolution approach of racemic phenylalanine with aqueous two-phase systems of chiral tropine ionic liquids.

    Science.gov (United States)

    Wu, Haoran; Yao, Shun; Qian, Guofei; Yao, Tian; Song, Hang

    2015-10-30

    Aqueous two-phase systems (ATPS) based on tropine type chiral ionic liquids and inorganic salt solution were designed and prepared for the enantiomeric separation of racemic phenylalanine. The phase behavior of IL-based ATPS was comprehensive investigated, and phase equilibrium data were correlated by Merchuk equation. Various factors were also systematically investigated for their influence on separation efficiency. Under the appropriate conditions (0.13g/g [C8Tropine]pro, 35mg/g Cu(Ac)2, 20mg/g d,l-phenylalanine, 0.51g/g H2O and 0.30g/g K2HPO4), the enantiomeric excess value of phenylalanine in solid phase (mainly containing l-enantiomer) was 65%. Finally, the interaction mechanism was studied via 1D and 2D NMR. The results indicate that d-enantiomer of phenylalanine interacts more strongly with chiral ILs and Cu(2+) based on the chiral ion-pairs space coordination mechanism, which makes it tend to remain in the top IL-rich phase. By contrast, l-enantiomer is transferred into the solid phase. Above chiral ionic liquids aqueous two-phase systems have demonstrated obvious resolution to racemic phenylalanine and could be promising alterative resolution approach for racemic amino acids in aqueous circumstance.

  11. ENANTIOMER SEPARATION OF POLYCHLORINATED BIPHENYL ATROPISOMERS AND POLYCHLORINATED BIPHENYL RETENTION BEHAVIOR ON MODIFIED CYCLODEXTRIN CAPILLARY GAS CHROMATOGRAPHY COLUMNS

    Science.gov (United States)

    Seven commercially-available chiral capillary gas chromatography columns containing modified cyclodextrins were evaluated for their ability to separate enantiomers of the 19 stable chiral polychlorinated biphenyl (PCB) atropisomers, and for their ability to separate these enantio...

  12. Evolutionary multi-objective optimization based comparison of multi-column chromatographic separation processes for a ternary separation.

    Science.gov (United States)

    Heinonen, Jari; Kukkonen, Saku; Sainio, Tuomo

    2014-09-01

    Performance characteristics of two advanced multi-column chromatographic separation processes with discontinuous feed, Multi-Column Recycling Chromatogrphy (MCRC) and Japan Organo (JO), were investigated for a ternary separation using multi-objective optimization with an evolutionary algorithm. Conventional batch process was used as a reference. Fractionation of a concentrated acid hydrolysate of wood biomass into sulfuric acid, monosaccharide, and acetic acid fractions was used as a model system. Comparison of the separation processes was based on selected performance parameters in their optimized states. Flow rates and step durations were taken as decision variables whereas the column configuration and dimensions were fixed. The MCRC process was found to be considerably more efficient than the other processes with respect to eluent consumption. The batch process gave the highest productivity and the JO process the lowest. Both of the multi-column processes gave significantly higher monosaccharide yield than the batch process. When eluent consumption and monosaccharide yield are taken into account together with productivity, the MCRC process was found to be the most efficient in the studied case. PMID:25060000

  13. Color chiral solitons

    CERN Document Server

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

    2002-01-01

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

  14. Synthesis and application of aryl-ferrocenyl(pseudo-biarylic) complexes. Part 5. Design and synthesis of a new type of ferrocene-based planar chiral DMAP analogues. A new catalyst system for asymmetric nucleophilic catalysis

    DEFF Research Database (Denmark)

    Seitzberg, J.G; Dissing, C; Søtofte, Inger;

    2005-01-01

    A new first-generation catalyst system for nucleophilic catalysis has been developed. It is based on a planar chiral ferrocene skeleton with either the potent nucleophile 4-(dimethylamino)pyridine (DMAP) or the related 4-nitropyridine N-oxide attached in either the 2- or the 3-position. The synth...

  15. Molecular-level Design of Heterogeneous Chiral Catalysts

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-28

    ) modified by a variety of chiral templates. • Demonstrated enantioselective separation of racemic PO on chemically synthesized chiral gold nanoparticles. • Discovery of zwitterionic adsorption states of amino acids on Pd(111). • First structure determinations of adsorbed amino acids and identification of tetrameric chiral template structures. • Exploration of the enantiospecific interaction of PO and R-3-MCHO adsorption on chirally modified Cu(100), Cu(110) and Cu(111). One-to-One Interactions • Determination of cinchona orientation on Pt surfaces in situ at the solid-liquid interface using FT-IRAS. • Systematic study of the influence of solution properties on the adsorption of modified cinchonas alkaloids onto Pt surfaces. • Correlation of cinchona adsorption with catalytic activity, as affected by concentration, the nature of the solvent, and dissolved gases in the liquid phase. • Measurement of enantioselective chemisorption on 1-(1-naphthyl) ethylamine (NEA) modified Pt(111) and Pd(111) surfaces. • Imaging of chiral docking complexes between NEA and methyl pyruvate on Pd(111). Chiral Catalyst Synthesis • Anchoring of cinchona alkaloid to surfaces • Synthesis of chiral Au nanoparticles and demonstration of their enantiospecific interactions with R- and S-PO. • Elucidation of the driving forces for chiral imprinting of Cu(100) by L- and D-lysine to form Cu(3,1,17)R&S facets.

  16. Magnetic separation of iron-based nanosorbents from watery solutions

    Science.gov (United States)

    Medvedeva, Irina; Bakhteeva, Iuliia; Zhakov, Sergey; Baerner, Klaus

    2016-04-01

    Iron and iron oxide magnetic nanoparticles (MNP) both naked and with chemically modified surface are promising agents for different environmental applications, in particular for water purification and for analytical control of water and soil pollution. The MNP can be used as sorbents with selective abilities due to designed surface functionalization. While a lot of research has been devoted to the impurity sorption processes, the second part, that is the efficient removal of the MNP sorbents from the watery solution, has not been sufficiently studied so far. For that particles with magnetic cores are especially attractive due to the possibility of their subsequent magnetic separation from water without using coagulants, i.e. without a secondary water pollution, just by applying external magnetic fields B. In order to remove magnetic sorbent nanoparticles ( 10-100 nm) effectively from the water solution gradient magnetic fields are required. Depending on the MNP size, the magnetic moment, the chemical properties of the solution, the water purification conditions , either the low gradient magnetic separation (LGMS) with dB/dz 100 T/m is used. The gradient magnetic field is provided by permanent magnets or electromagnets of different configuration. In this work the sedimentation dynamics of naked Fe3O4 and Fe3O4@SiO2 nanoparticles (10-30 nm) in water was studied in a vertical gradient magnetic field (B1 ≤ 0.3T, dB/dz ≤ 0.13 T/cm). By this LGMS , the sedimentation time of the naked Fe3O4 NP is reduced down from several days to several minutes. The sedimentation time for Fe3O4@SiO2 decreases from several weeks to several hours and to several minutes when salts Na2SO4, CaCl2, NaH2PO4 are added to the solution. The results are interpreted in terms of MNP aggregate formation caused by electrostatic, steric and magnetic inter-particle interactions in the watery solution. ACKNOWLEDGMENTS The work was supported in part by the Ural Branch, Russian Academy of Sciences

  17. Sample injection and electrophoretic separation on a simple laminated paper based analytical device.

    Science.gov (United States)

    Xu, Chunxiu; Zhong, Minghua; Cai, Longfei; Zheng, Qingyu; Zhang, Xiaojun

    2016-02-01

    We described a strategy to perform multistep operations on a simple laminated paper-based separation device by using electrokinetic flow to manipulate the fluids. A laminated crossed-channel paper-based separation device was fabricated by cutting a filter paper sheet followed by lamination. Multiple function units including sample loading, sample injection, and electrophoretic separation were integrated on a single paper based analytical device for the first time, by applying potential at different reservoirs for sample, sample waste, buffer, and buffer waste. As a proof-of-concept demonstration, mixed sample solution containing carmine and sunset yellow were loaded in the sampling channel, and then injected into separation channel followed by electrophoretic separation, by adjusting the potentials applied at the four terminals of sampling and separation channel. The effects of buffer pH, buffer concentration, channel width, and separation time on resolution of electrophoretic separation were studied. This strategy may be used to perform multistep operations such as reagent dilution, sample injection, mixing, reaction, and separation on a single microfluidic paper based analytical device, which is very attractive for building micro total analysis systems on microfluidic paper based analytical devices.

  18. Chiral Odd GPDs

    Directory of Open Access Journals (Sweden)

    Goldstein Gary R.

    2015-01-01

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

  19. Separation of thorium and uranium in nitric acid solution using silica based anion exchange resin.

    Science.gov (United States)

    Chen, Yanliang; Wei, Yuezhou; He, Linfeng; Tang, Fangdong

    2016-09-30

    To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method.

  20. Ultrasound-induced emission enhancement based on structure-dependent homo- and heterochiral aggregations of chiral binuclear platinum complexes.

    Science.gov (United States)

    Komiya, Naruyoshi; Muraoka, Takako; Iida, Masayuki; Miyanaga, Maiko; Takahashi, Koichi; Naota, Takeshi

    2011-10-12

    Instant and precise control of phosphorescent emission can be performed by ultrasound-induced gelation of organic liquids with chiral, clothespin-shaped trans-bis(salicylaldiminato)Pt(II) complexes, anti-1. Nonemissive solutions of racemic, short-linked anti-1a (n = 5) and optically pure, long-linked anti-1c (n = 7) in organic liquids are transformed immediately into stable phosphorescent gels upon brief irradiation of low-power ultrasound. Emission from the gels can be controlled by sonication time, linker length, and optical activity of the complexes. Several experimental results indicated that structure-dependent homo- and heterochiral aggregations and ultrasound-control of the aggregate morphology are key factors for emission enhancement. PMID:21894951

  1. New Enantiomerically Pure Alkylimido Mo-Based Complexes. Synthesis, Characterization, and Activity as Chiral Olefin Metathesis Catalysts

    Science.gov (United States)

    Pilyugina, Tatiana S.; Schrock, Richard R.; Müller, Peter; Hoveyda, Amir H.

    2008-01-01

    Molybdenum olefin metathesis catalysts that contain aliphatic 1-phenylcyclohexylimido (NPhCy) and 2-phenyl-2-adamantylimido (NPhAd) groups and (S)-Biphen or (R)-Trip)(THF) ligands (Biphen = 3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diolate; Trip = 3,3′-bis(2,4,6-triisopropylphenyl)-2,2′-binaphtholate) have been prepared. Their catalytic activity and enantioselectivity in desymmetrization reactions such as ring-closing metathesis of amines and lactams and ring-opening/cross-metathesis of substituted norborneols with styrene were compared to the results obtained with the only known alkylimido catalyst Mo(NAd)(CHCMe2Ph)[(S)-Biphen]. The activities and enantioselectivities provided by these new chiral complexes vary significantly, but in virtually all instances explored were not superior to the adamantylimido analogs. PMID:19079732

  2. Research and Simulation of FECG Signal Blind Separation Algorithm Based on Gradient Method

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2012-08-01

    Full Text Available Independent Component Analysis (ICA is a new developed signal separation and digital analysis technology in recent years. ICA has widely used because it does not need to know the signal prior information, which has became the hot spot in signal processing field research. In this study, we firstly introduce the principle, meaning and blind source separation algorithm based on the gradient. By using the traditional natural gradient algorithm and Equi-variant Adaptive Source Separation via Independent (EASI blind separation algorithm, mixing ECG signals with noises had been separated effectively into the Maternal Electrocardiograph (MECG signal, Fetal Electrocardiograph (FECG signal and noise signal. The algorithm separation test showed that EASI algorithm can better separate the fetal ECG signal and because the gradient algorithm is a kind of online algorithm, which can be used for clinical fetal ECG signal of the real-time detection with important practical value and research significance.

  3. Separation of enantiomers by capillary electrophoresis using pentosan polysulfate.

    Science.gov (United States)

    Wang, X; Lee, J T; Armstrong, D W

    1999-01-01

    Pentosan polysulfate, a semisynthetic polysaccharide, was employed as a chiral run buffer additive in capillary electrophoresis. Twenty-eight racemic analytes were resolved. The separations were successful only at low pH when the analytes were significantly protonated. This suggests that ionic interactions were the dominant associative interactions between the anionic pentosan polysulfate and the positively charged analytes. Compared to other linear, carbohydrate-based chiral selectors (i.e., chondroitin sulfates, heparin and dextran sulfate) pentosan polysulfate has some characteristics common of anionic polysaccharides; yet it has several differences in its structure and properties which account for its unusual enantioselectivity. The effects of pH, concentration of phosphate buffer, concentration of pentosan polysulfate and the type and concentration of organic modifier on the enantiomeric separations were investigated. The optimization of these separations were dependent on the nature of the analytes and could be achieved by the proper choice of experimental conditions.

  4. Split Fermi Surface Properties based on the Relativistic Effect in Superconductor PdBiSe with the Cubic Chiral Crystal Structure

    Science.gov (United States)

    Kakihana, Masashi; Nakamura, Ai; Teruya, Atsushi; Harima, Hisatomo; Haga, Yoshinori; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2015-03-01

    We grew single crystals of PdBiSe with the ullmannite-type cubic chiral structure and carried out de Haas-van Alphen (dHvA) experiments to clarify the Fermi surface properties. The Fermi surfaces are found to split into two different Fermi surfaces, reflecting the non-centrosymmetric crystal structure. A splitting energy between two nearly spherical Fermi surfaces named α and α' is determined as 1050-1260 K. These Fermi surfaces are identified to be due the band-149 and -150 electron Fermi surfaces centered at the Γ point from the results of full-potential linearized augmented plane wave (FLAPW) energy band calculations under consideration of a mass correction in the spin-orbit interaction for Bi-6p electrons based on the relativistic effect. The theoretical splitting energy between these Fermi surfaces is 1080-1150 K, which is in good agreement with the experimental value.

  5. Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II-based metalloradical catalysis

    Directory of Open Access Journals (Sweden)

    Jingran Tao

    2014-06-01

    Full Text Available The Co(II complex of a new D2-symmetric chiral porphyrin 3,5-DiMes-QingPhyrin, [Co(P6], can catalyze asymmetric aziridination of alkenes with bis(2,2,2-trichloroethylphosphoryl azide (TcepN3 as a nitrene source. This new Co(II-based metalloradical aziridination is suitable for different aromatic olefins, producing the corresponding N-phosphorylaziridines in good to excellent yields (up to 99% with moderate to high enantioselectivities (up to 85% ee. In addition to mild reaction conditions and generation of N2 as the only byproduct, this new metalloradical catalytic system is highlighted with a practical protocol that operates under neutral and non-oxidative conditions.

  6. Separable and non-separable discrete wavelet transform based texture features and image classification of breast thermograms

    Science.gov (United States)

    Etehadtavakol, Mahnaz; Ng, E. Y. K.; Chandran, Vinod; Rabbani, Hossien

    2013-11-01

    Highly sensitive infrared cameras can produce high-resolution diagnostic images of the temperature and vascular changes of breasts. Wavelet transform based features are suitable in extracting the texture difference information of these images due to their scale-space decomposition. The objective of this study is to investigate the potential of extracted features in differentiating between breast lesions by comparing the two corresponding pectoral regions of two breast thermograms. The pectoral regions of breastsare important because near 50% of all breast cancer is located in this region. In this study, the pectoral region of the left breast is selected. Then the corresponding pectoral region of the right breast is identified. Texture features based on the first and the second sets of statistics are extracted from wavelet decomposed images of the pectoral regions of two breast thermograms. Principal component analysis is used to reduce dimension and an Adaboost classifier to evaluate classification performance. A number of different wavelet features are compared and it is shown that complex non-separable 2D discrete wavelet transform features perform better than their real separable counterparts.

  7. Dynamic control of chirality in phosphine ligands for enantioselective catalysis

    NARCIS (Netherlands)

    Zhao, Depeng; Neubauer, Thomas M; Feringa, Ben L

    2015-01-01

    Chirality plays a fundamental role in biology and chemistry and the precise control of chirality in a catalytic conversion is a key to modern synthesis most prominently seen in the production of pharmaceuticals. In enantioselective metal-based catalysis, access to each product enantiomer is commonly

  8. Nucleon Properties from Approximating Chiral Quark Sigma Model

    CERN Document Server

    Abu-Shady, M

    2009-01-01

    We apply the approximating chiral quark model. This chiral quark model is based on an effective Lagrangian which the interactions between quarks via sigma and pions mesons. The field equations have been solved in the mean field approximation for the hedgehog baryon state. Good results are obtained for nucleon properties in comparison with original model.

  9. Circular dichroism of graphene oxide: the chiral structure model

    Institute of Scientific and Technical Information of China (English)

    Jing CAO; Hua-Jie YIN; Rui SONG

    2013-01-01

    We have observed the circular dichroism signal of dilute graphene oxide (GO), then systematically investigated the chirality of GO and established a probable chiral unit model, This study may open up a new field for understanding the structure of GO and lay the foundation for fabrication of GO-based materials.

  10. Asymmetric Imine Isomerisation in the Enantioselective Synthesis of Chiral Amines from Prochiral Ketones

    NARCIS (Netherlands)

    Willems, Johannes G.H.; Vries, Johannes G. de; Nolte, Roeland J.M.; Zwanenburg, Binne

    1995-01-01

    An asymmetric catalytic synthesis of chiral amines using a chiral base catalysed [1,3]-proton shift reaction of imines is described. The isomerisation reaction of N-benzylimines derived from prochiral ketones (benzylacetone, acetophenone) and p-substituted benzylamines, is catalysed by chiral alcoho

  11. Towards Separation of Concerns in Flow-Based Programming

    DEFF Research Database (Denmark)

    Zarrin, Bahram; Baumeister, Hubert

    2015-01-01

    Flow-Based Programming (FBP) is a programming paradigm that models software systems as a directed graph of predefined processes which run asynchronously and exchange data through input and output ports. FBP decomposes software systems into a network of processes. However there are concerns...

  12. Aluminum oxyhydroxide based separator/electrolyte and battery system, and a method of making the same

    Science.gov (United States)

    Gerald, II; Rex E.; Klingler, Robert J.; Rathke, Jerome W.

    2011-02-15

    The instant invention relates a solid-state electrochemical cell and a novel separator/electrolyte incorporated therein. The invented electrochemical cell generally comprising: a unique metal oxyhydroxide based (i.e. AlOOH) separator/electrolyte membrane sandwiched between a first electrode and a second electrode. The novel separator/electrolyte comprises a nanoparticulate metal oxyhydroxide, preferably AlOOH and a salt which are mixed and then pressed together to form a monolithic metal oxyhydroxide-salt membrane.

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

    Science.gov (United States)

    Levi, Gila; Scolnik, Yosef; Mastai, Yitzhak

    2016-09-01

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

  14. InGaN-based greenish separate confinement heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ebeling, Jakob; Aschenbrenner, Timo; Tessarek, Christian; Figge, Stefan; Hommel, Detlef [Institut fuer Festkoerperphysik, Universitaet Bremen (Germany)

    2010-07-01

    For opto-electronic applications green laser diodes (LDs) are of great interest. The fabrication of such GaN-based light emitting diodes (LEDs) and LDs however faced different problems ranging from the lack of adequate homoepitaxial substrates to the miscibility gap of InGaN. Recently there have been reports of laser diodes based on InGaN quantum wells (QWs) in the green spectral region. In this work the influence of InGaN quantum dots (QDs) on the opto-electronic properties of LDs is discussed in detail. All samples were grown by metal-organic vapour-phase epitaxy on free-standing GaN substrates from Lumilog and the number of QD stacks or QWs was varied. The samples were processed as ridge and deep ridge waveguide structures with different ridge widths and measured by high-resolution X-ray diffraction and electroluminescence, and light-current (L-I) and current-voltage (I-V) characteristics were recorded. A comparison of all different growths and process designs in respect of opto-electronic properties is presented.

  15. Band Interaction between Chiral Doublet Bands

    Institute of Scientific and Technical Information of China (English)

    QI Bin; ZHANG Shuang-Quan; WANG Shou-Yu; MENG Jie

    2010-01-01

    @@ Band interaction between the chiral doublet bands based on πh11/2(×) vh-111/2 configuration is investigated in the particle rotor model with different triaxial deformation γ. The variation of chiral partner states with γvalues is understood qualitatively based on the basic picture of two interaction levels, which is confirmed further by the calculated overlap integral of wave functions at different γ values. It is found that the interaction strengths ofchiral partner states are obvionsly different for odd spins and even ones.

  16. THE SEPARATION OF BASE METALS FROM PLATINUM METALS BY ION EXCHANGE

    Institute of Scientific and Technical Information of China (English)

    JIANGLingen; HUANGYan

    1992-01-01

    In this paper the separation of base metals Fe,Co,Ni and Cu from the platinum metals on a cation exchanger column was studies.The convenient separation conditions are 0.5mol·dm-3 NaCl,pH=2. The recovery efficiency of Rh is 98%.

  17. Chiral anomalies and differential geometry

    Energy Technology Data Exchange (ETDEWEB)

    Zumino, B.

    1983-10-01

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

  18. Aldol Reactions of Axially Chiral 5-Methyl-2-(o-arylimino-3-(o-aryl-thiazolidine-4-ones

    Directory of Open Access Journals (Sweden)

    Sule Erol Gunal

    2016-06-01

    Full Text Available Axially chiral 5-methyl-2-(o-arylimino-3-(o-aryl-thiazolidine-4-ones have been subjected to aldol reactions with benzaldehyde to produce secondary carbinols which have been found to be separable by HPLC on a chiral stationary phase. Based on the reaction done on a single enantiomer resolved via a chromatographic separation from a racemic mixture of 5-methyl-2-(α-naphthylimino-3-(α-naphthyl-thiazolidine-4-one by HPLC on a chiral stationary phase, the aldol reaction was shown to proceed via an enolate intermediate. The axially chiral enolate of the thiazolidine-4-one was found to shield one face of the heterocyclic ring rendering face selectivity with respect to the enolate. The selectivities observed at C-5 of the ring varied from none to 11.5:1 depending on the size of the ortho substituent. Although the aldol reaction proceeded with a lack of face selectivity with respect to benzaldehyde, recrystallization returned highly diastereomerically enriched products.

  19. An incentive-based source separation model for sustainable municipal solid waste management in China.

    Science.gov (United States)

    Xu, Wanying; Zhou, Chuanbin; Lan, Yajun; Jin, Jiasheng; Cao, Aixin

    2015-05-01

    Municipal solid waste (MSW) management (MSWM) is most important and challenging in large urban communities. Sound community-based waste management systems normally include waste reduction and material recycling elements, often entailing the separation of recyclable materials by the residents. To increase the efficiency of source separation and recycling, an incentive-based source separation model was designed and this model was tested in 76 households in Guiyang, a city of almost three million people in southwest China. This model embraced the concepts of rewarding households for sorting organic waste, government funds for waste reduction, and introducing small recycling enterprises for promoting source separation. Results show that after one year of operation, the waste reduction rate was 87.3%, and the comprehensive net benefit under the incentive-based source separation model increased by 18.3 CNY tonne(-1) (2.4 Euros tonne(-1)), compared to that under the normal model. The stakeholder analysis (SA) shows that the centralized MSW disposal enterprises had minimum interest and may oppose the start-up of a new recycling system, while small recycling enterprises had a primary interest in promoting the incentive-based source separation model, but they had the least ability to make any change to the current recycling system. The strategies for promoting this incentive-based source separation model are also discussed in this study. PMID:25819930

  20. Rational design of a redox-labeled chiral target for an enantioselective aptamer-based electrochemical binding assay.

    Science.gov (United States)

    Moreau, Julie; Challier, Lylian; Lalaoui, Noémie; Mavré, François; Noël, Vincent; Limoges, Benoît; Schöllhorn, Bernd; Fave, Claire

    2014-03-01

    A series of redox-labeled L-tyrosinamide (L-Tym) derivatives was prepared and the nature of the functional group and the chain length of the spacer were systematically varied in a step-by-step affinity optimization process of the tracer for the L-Tym aptamer. The choice of the labeling position on L-Tym proved to be crucial for the molecular recognition event, which could be monitored by cyclic voltammetry and is based on the different diffusion rates of free and bound targets in solution. From this screening approach an efficient electroactive tracer emerged. Comparable dissociation constants Kd were obtained for the unlabeled and labeled targets in direct or competitive binding assays. The enantiomeric tracer was prepared and its enantioselective recognition by the corresponding anti-D-Tym aptamer was demonstrated. The access to both enantiomeric tracer molecules opens the door for the development of one-pot determination of the enantiomeric excess when using different labels with well-separated redox potentials for each enantiomer. PMID:24519626

  1. Chiral density wave in nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Heinz, Achim [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Giacosa, Francesco [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Rischke, Dirk H. [Institute for Theoretical Physics, Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany)

    2015-01-15

    Inspired by recent work on inhomogeneous chiral condensation in cold, dense quark matter within models featuring quark degrees of freedom, we investigate the chiral density-wave solution in nuclear matter at zero temperature and nonvanishing baryon number density in the framework of the so-called extended linear sigma model (eLSM). The eLSM is an effective model for the strong interaction based on the global chiral symmetry of quantum chromodynamics (QCD). It contains scalar, pseudoscalar, vector, and axial-vector mesons as well as baryons. In the latter sector, the nucleon and its chiral partner are introduced as parity doublets in the mirror assignment. The eLSM simultaneously provides a good description of hadrons in vacuum as well as nuclear matter ground-state properties. We find that an inhomogeneous phase in the form of a chiral density wave is realized, but only for densities larger than 2.4ρ{sub 0}, where ρ{sub 0} is the nuclear matter ground-state density.

  2. Quantitatively analyzing intrinsic plasmonic chirality by tracking the interplay of electric and magnetic dipole modes

    CERN Document Server

    Hu, Li; Fang, Yurui

    2016-01-01

    Plasmonic chirality exhibits great potential for novel nanooptical devices due to the generation of a strong chiroptical response. Previous reports on plasmonic chirality explanations are mainly based on phase retardation and coupling. We propose a quantitative model similar to the chiral molecules for explaining the mechanism of the intrinsic plasmonic chirality quantitatively based on the interplay and mixing of electric and magnetic dipole modes, which forms a mixed electric and magnetic polarizability. The analysis method is also suitable for small chiral object down to quasi-static limit without phase delay and expected to be a universal rule.

  3. Nanoscale membrane-based technology for the separation of actinides and other elements

    International Nuclear Information System (INIS)

    The separation of elements, in particular actinides, in the aqueous homogeneous phase using polymer reagents is presented and outlined in view of membrane-based separation technologies. The concept of separation based on the retention of polymer complexes in aqueous solution, which are separated according to their molecular size, is explained. These hybrid processes are combining the complexing agents with the method of ultra- or nanofiltration. The fundamentals of the element interaction in relation to the separation procedures are discussed, and the role of the polymer reagent is assessed. Typical examples are discussed and the major factors influencing the processes are investigated. In addition, recent developments for actinides using this method are also described. (author)

  4. Blind Source Separation Based on Covariance Ratio and Artificial Bee Colony Algorithm

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2014-01-01

    Full Text Available The computation amount in blind source separation based on bioinspired intelligence optimization is high. In order to solve this problem, we propose an effective blind source separation algorithm based on the artificial bee colony algorithm. In the proposed algorithm, the covariance ratio of the signals is utilized as the objective function and the artificial bee colony algorithm is used to solve it. The source signal component which is separated out, is then wiped off from mixtures using the deflation method. All the source signals can be recovered successfully by repeating the separation process. Simulation experiments demonstrate that significant improvement of the computation amount and the quality of signal separation is achieved by the proposed algorithm when compared to previous algorithms.

  5. ICA Based Speckle Filtering for Target Extraction in SAR Images Using Adaptive Space Separation

    Institute of Scientific and Technical Information of China (English)

    LI Yu-tong; ZHOU Yue; YANG Lei

    2008-01-01

    A novel approach based on independent component analysis (ICA) for speckle filtering and target extraction of synthetic aperture radar (SAR) images is proposed using adaptive space separation with weighted information entropy (WIE) incorporated. First the basis and the independent components are respectively obtained by ICA technique, and WIE of the image is computed; then based on the threshold computed from function T-WIE (threshold versus weighted-information-entropy), independent components are adaptively separated and the bases are classified accordingly. Thus, the image space is separated into two subspaces: "clean" and "noise". Then, a proposed nonlinear operator ABO is applied on each component of the 'clean' subspace for further optimization. Finally, recovery image is obtained reconstructing this subspace and target is easily extracted with binarisation. Note that here T-WIE is an interpolated function based on several representative target SAR images using proposed space separation algorithm.

  6. Holographic Chiral Magnetic Spiral

    International Nuclear Information System (INIS)

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

  7. Chiral symmetry and strangeness at SIS energies

    International Nuclear Information System (INIS)

    In this talk we review the consequences of the chiral SU(3) symmetry for strangeness propagation in nuclear matter. Objects of crucial importance are the meson-baryon scattering amplitudes obtained within the chiral coupled-channel effective field theory. Results for antikaon and hyperon-resonance spectral functions in cold nuclear matter are presented and discussed. The importance of the Σ(1385) resonance for the subthreshold antikaon production in heavy-ion reaction at SIS is pointed out. The in-medium properties of the latter together with an antikaon spectral function based on chiral SU(3) dynamics suggest a significant enhancement of the π Λ → anti Κ N reaction in nuclear matter. (orig.)

  8. Chiral quark model

    Indian Academy of Sciences (India)

    H Weigel

    2003-11-01

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

  9. Chirality and Life

    Science.gov (United States)

    Barron, Laurence D.

    2008-03-01

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

  10. Chiral Heat Wave and wave mixing in chiral media

    CERN Document Server

    Chernodub, M N

    2016-01-01

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

  11. Authenticity of raspberry flavor in food products using SPME-chiral-GC-MS

    DEFF Research Database (Denmark)

    Hansen, Anne-Mette Sølvbjerg; Frandsen, Henrik Lauritz; Fromberg, Arvid

    2015-01-01

    A fast and simple method for authenticating raspberry flavors from food products was developed. The two enantiomers of the compound (E)-α-ionone from raspberry flavor were separated on a chiral gas chromatographic column. Based on the ratio of these two enantiomers the naturalness of a raspberry...... flavor can be evaluated due to the fact that a natural flavor will consist almost exclusively of the R enantiomer, while a chemical synthesis of the same compound will result in a racemic mixture. 27 food products containing raspberry flavors where investigated using SPME-chiral-GC-MS. We found raspberry...... jam, dried raspberries and sodas declared to contain natural aroma all contained almost only R-(E)-α-ionone supporting the content of natural raspberry aroma. Six out of eight sweets tested did not indicate a content of natural aroma on the labelling which was in agreement with the almost equal...

  12. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    Science.gov (United States)

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

    2015-12-01

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

  13. Asymmetric synthesis of α-amino-1,3-dithianes via chiral N-phosphonyl imine-based Umpolung reaction without using chromatography and recrystallization.

    Science.gov (United States)

    Kattamuri, Padmanabha V; Ai, Teng; Pindi, Suresh; Sun, Yinwei; Gu, Peng; Shi, Min; Li, Guigen

    2011-04-15

    A series of α-amino-1,3-dithianes have been synthesized via the asymmetric Umpolung reaction of 2-lithio-1,3-dithianes with chiral N-phosphonyl imines in good chemical yields (up to 82%) and good to excellent diastereoselectivities (>99:1). The manner by which chiral N-phosphonyl imines are slowly added into the solution of 2-lithio-1,3-dithiane was found to be crucial for achieving excellent diastereoselectivity. The current synthesis was proven to follow the GAP chemistry (group-assistant-purification chemistry) process, which avoids traditional purification techniques of chromatography or recrystallization, i.e., the pure chiral α-amino-1,3-dithianes attached with the chiral N-phosphonyl group were readily obtained by washing the solid crude products with hexane or a mixture of hexane-ethyl acetate.

  14. Separability Criterion for Arbitrary Multipartite Pure State Based on the Rank of Reduced Density Matrix

    Science.gov (United States)

    Zhao, Chao; Yang, Guo-wu; Li, Xiao-yu

    2016-09-01

    Nowadays, there are plenty of separability criteria which are used to detect entanglement. Many of them are limited to apply for some cases. In this paper, we propose a separability criterion for arbitrary multipartite pure state which is based on the rank of reduced density matrix. It is proved that the rank of reduced density matrices of a multipartite state is closely related to entanglement. In fact it can be used to characterize entanglement. Our separability criterion is a necessary and sufficient condition for detecting entanglement. Furthermore, it is able to help us find the completely separable form of a multipartite pure state according to some explicit examples. Finally it demonstrates that our method are more suitable for some specific case. Our separability criterion are simple to understand and it is operational.

  15. Chiral forces and molecular dissymmetry

    International Nuclear Information System (INIS)

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

  16. Local topological and chiral properties of QCD

    CERN Document Server

    De Forcrand, Philippe; Laermann, E; Lagaë, J F; Pérez-Garcia, M; Stamatescu, I O; Forcrand, Ph. de

    1999-01-01

    To elucidate the role played by instantons in chiral symmetry breaking, we explore their properties in full QCD, around the critical temperature. We study in particular spatial correlations between low-lying Dirac eigenmodes and instantons. Our measurements are compared with the predictions of instanton-based models.

  17. Interweaving Chiral Spirals

    CERN Document Server

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

    2011-01-01

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

  18. Feature selection by separability assessment of input spaces for transient stability classification based on neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Tso, S.K. [City University of Hong Kong (China). Dept. of Manufacturing Engineering; Gu, X.P. [North China Electric Power University, Baoding (China). Dept. of Electrical Engineering

    2004-03-01

    Power system transient-stability assessment based on neural networks can usually be treated as a two-pattern classification problem separating the stable class from the unstable class. In such a classification problem, the feature extraction and selection is the first important task to be carried out. A new approach of feature selection is presented using a new separability measure in this paper. Through finding the 'inconsistent cases' in a sample set, a separability index of input spaces is defined. Using the defined separability index as criterion, the breadth-first searching technique is employed to find the minimal or optimal subsets of the initial feature set. The numerical results based on extensive data obtained for the 10-unit 39-bus New England power system demonstrate the effectiveness of the proposed approach in extracting the 'best combination' of features for improving the quality of transient-stability classification. (author)

  19. Single channel source separation of radar fuze mixed signal based on phase difference analysis

    Institute of Scientific and Technical Information of China (English)

    Hang ZHU; Shu-ning ZHANG; Hui-chang ZHAO

    2014-01-01

    A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze. This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals, solve the candidate data set by the mixing coefficients and signal analytical form, and resolve the problem of vector ambiguity by analyzing the phase differences. The signal separation is realized by exchanging data of the solutions. The waveform similarity coefficients are calculated, and the timeefrequency dis-tributions of separated signals are analyzed. The results show that the proposed method is effective.

  20. Aluminum oxyhydroxide based separator/electrolyte and battery system, and a method making the same

    Science.gov (United States)

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.

    2011-03-08

    The instant invention relates a solid-state electrochemical cell and a novel separator/electrolyte incorporated therein. A preferred embodiment of the invented electrochemical cell generally comprises a unique metal oxyhydroxide based (i.e. AlOOH) separator/electrolyte membrane sandwiched between a first electrode and a second electrode. A preferred novel separator/electrolyte comprises a nanoparticulate metal oxyhydroxide, preferably AlOOH and a salt which are mixed and then pressed together to form a monolithic metal oxyhydroxide-salt membrane.

  1. Chiral vanadium(V) complexes with 2-aminoglucose Schiff-base ligands and their solution configurations: synthesis, structures, and DFT calculations.

    Science.gov (United States)

    Mohammadnezhad, Gholamhossein; Böhme, Michael; Geibig, Daniel; Burkhardt, Anja; Görls, Helmar; Plass, Winfried

    2013-09-01

    The sugar-modified Schiff-base ligands derived from benzyl 2-deoxy-2-salicylideneamino-α-D-glucopyranoside (H2L(5-Br) and H2L(3-OMe)) were used to prepare the chiral oxidovanadium(V) complexes [VO(L(5-Br))(OMe)] (1) and [VO(L(3-OMe))(OMe)] (2) which can be isolated from a methanol solution as the six-coordinate complexes with an additional methanol ligand [VO(L(5-Br))(OMe)(MeOH)] (1-MeOH) and [VO(L(3-OMe))(OMe) (MeOH)] (2-MeOH). Both complexes crystallize in the orthorhombic space group P2(1)2(1)2(1) together with two solvent molecules of methanol as 1-MeOH·2MeOH and 1-MeOH·2MeOH. In both crystal structures, only diastereomers with A configuration at the chiral vanadium centre (OC-6-24-A) are observed which corresponds to an cis configuration of the oxido group at the vanadium centre and the benzyl group at the anomeric carbon of the sugar backbone. Upon recrystallization of 2-MeOH from chloroform, the five-coordinate complex 2 was obtained which crystallizes in the monoclinic space group P2(1) with one co-crystallized chloroform molecule (2·CHCl3). For the chiral vanadium centre in 2·CHCl3, a C configuration (SPY-5-43-C) is observed which corresponds to an trans structure as far as the orientations of the oxido and benzyl groups are concerned. (1)H and (51)V NMR spectra of 1 and 2 indicate the presence of two diastereomers in solution. Their absolute configurations can be assigned based on the magnetic anisotropy effect of the oxidovanadium group. This effect leads to significant differences for the (1)H NMR chemical shifts of the H-2 (1.1 ppm) and H-3 protons (0.3 ppm) of the glucose backbone of the two diastereomers, with the downfield shift observed for the H-2 proton of the C-configured and the H-3 proton of the A-configured diastereomer at the vanadium centre. For 1 and 2 the difference between the (51)V NMR chemical shifts of the two diastereomers is 30 and 28 ppm, respectively. Also in the (13)C NMR significant chemical shift differences between the

  2. Cellulose acetate-based molecularly imprinted polymeric membrane for separation of vanillin and o-vanillin

    OpenAIRE

    Chunjing Zhang; Shian Zhong; Zhengpeng Yang

    2008-01-01

    Cellulose acetate-based molecularly imprinted polymeric membranes were prepared using vanillin as template molecule. The microscopic structure of the resultant polymeric membranes was characterized by SEM and FTIR spectroscopy, and the selective binding properties and separation capacity of the membranes for vanillin and o-vanillin were tested with binding experiments and separate experiments, respectively. The results showed that the vanillin-imprinted polymeric membranes displayed higher bi...

  3. Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation

    Science.gov (United States)

    Yuan, S. W. K.; Frederking, T. H. K.

    1989-01-01

    Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.

  4. Subband-based Single-channel Source Separation of Instantaneous Audio Mixtures

    OpenAIRE

    Taghia, Jalil; Doostari, Mohammad Ali

    2009-01-01

    In this paper, a new algorithm is developed to separate the audio sources from a single instantaneous mixture. The algorithm is based on subband decomposition and uses a hybrid system of Empirical Mode Decomposition (EMD) and Principle Component Analysis (PCA) to construct artificial observations from the single mixture. In the separation stage of algorithm, we use Independent Component Analysis (ICA) to find independent components. At first the observed mixture is divided into a finite numbe...

  5. High-efficiency spatial color separation method based on fractional Talbot effect

    Institute of Scientific and Technical Information of China (English)

    Qiaofeng Tan; Yan Zhang; Guofan Jin

    2009-01-01

    @@ Based on fractional Talbot effect, Talbot grating is adopted to realize spatial color separation with high light efficiency.For red and green colors, a two-step Talbot grating is optimized and the light efficiency reaches over 95%.The two-step Talbot grating is fabricated and tested.Experimental results show that the Talbot grating indeed has the good ability of spatial color separation.

  6. Ultra-microporous triptycene-based polyimide membranes for high-performance gas separation

    KAUST Repository

    Ghanem, Bader

    2014-03-11

    A highly permeable and highly selective polyimide of intrinsic microporosity is prepared using a 9,10-diisopropyl-triptycene contortion center. The three-dimensionality and shape-persistence of triptycene afford exceptional sieving-based gas separation performance transcending the latest permeability/selectivity trade-offs for industrial gas separations involving oxygen and hydrogen. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Membrane-based, sedimentation-assisted plasma separator for point-of-care applications

    Science.gov (United States)

    Liu, Changchun; Mauk, Michael; Gross, Robert; Bushman, Frederic D.; Edelstein, Paul H.; Collman, Ronald G.; Bau, Haim H.

    2014-01-01

    Often, high sensitivity, point of care, clinical tests, such as HIV viral load, require large volumes of plasma. Although centrifuges are ubiquitously used in clinical laboratories to separate plasma from whole blood, centrifugation is generally inappropriate for on-site testing. Suitable alternatives are not readily available to separate the relatively large volumes of plasma from milliliters of blood that may be needed to meet stringent limit-of-detection specifications for low abundance target molecules. We report on a simple to use, low-cost, pump-free, membrane-based, sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes. This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a “blood in-plasma out” capability, consistently extracting 275 ±33.5 μL of plasma from 1.8 mL of undiluted whole blood in less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3,500 and 350 copies/mL, respectively. The separation process is self-terminating to prevent excessive hemolysis. The HIV-laden plasma was then injected into our custom-made microfluidic chip for nucleic acid Testing And Was Successfully Subjected To Reverse Transcriptase Loop mediated isothermal amplification (RT-LAMP), demonstrating that the plasma is sufficiently pure to support high efficiency nucleic acid amplification. PMID:24099566

  8. Detecting the chirality for coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-04-21

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

  9. Separation of base flow from streamflow using groundwater levels - illustrated for the Pang catchment (UK)

    NARCIS (Netherlands)

    Peters, E.; Lanen, van H.A.J.

    2005-01-01

    A new filter to separate base flow from streamflow has developed that uses observed groundwater levels. To relate the base flow to the observed groundwater levels, a non-linear relation was used. This relation is suitable for unconfined aquifers with deep groundwater levels that do not respond to in

  10. A Nonperturbative Regulator for Chiral Gauge Theories

    CERN Document Server

    Grabowska, Dorota M

    2015-01-01

    We propose a nonperturbative gauge invariant regulator for $d$-dimensional chiral gauge theories on the lattice. The method involves simulating domain wall fermions in $d+1$ dimensions with quantum gauge fields that reside on one $d$-dimensional surface and are extended into the bulk via gradient flow. The result is a theory of gauged fermions plus mirror fermions, where the mirror fermions couple to the gauge fields via a form factor that becomes exponentially soft with the separation between domain walls. The resultant theory has a local $d$-dimensional interpretation if and only if the chiral fermion representation is anomaly free. A physical realization of this construction leads to mirror fermions in the Standard Model with soft form factors for gauge fields and gravity. These mirror particles could evade detection except by sensitive probes at extremely low energy, and yet still affect vacuum topology, and could gravitate differently than conventional matter.

  11. Nonperturbative Regulator for Chiral Gauge Theories?

    Science.gov (United States)

    Grabowska, Dorota M.; Kaplan, David B.

    2016-05-01

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

  12. New approaches in sensitive chiral CE.

    Science.gov (United States)

    Sánchez-Hernández, Laura; Guijarro-Diez, Miguel; Marina, María Luisa; Crego, Antonio L

    2014-01-01

    CE has shown to have a big potential for chiral separations, with advantages such as high efficiency, high resolution, and low sample and reagents consumption. Nevertheless, when UV detection is employed, CE has some drawbacks, especially the low sensitivity obtained due to the short optical path length. Notwithstanding, sensitivity improvements can be achieved when different approaches are employed, such as sample treatment strategies (off-line or on-line), in-capillary sample preconcentration techniques, and/or alternative detection systems to UV-Vis (such as fluorescence, conductimetry, electrochemiluminiscence, MS, etc.). This article reviews the most recent methodological and instrumental advances reported from June 2011 to May 2013 for enhancing the sensitivity in chiral analysis by CE. The sensitivity achieved for the enantioseparated analytes and the applications carried out using the developed methodologies are also summarized.

  13. Preparation of a new chiral stationary phase for HPLC based on the (R)- 1-phenyl-2-(4-methylphenyl)ethylamine amide derivative of (S)-valine and 2-chloro-3,5-dinitrobenzoic acid: enantioseparation of amino acid derivatives and pyrethroid insecticides.

    Science.gov (United States)

    Tan, Xulin; Hou, Shicong; Jiang, Jingli; Wang, Min

    2007-08-01

    A novel chiral stationary phase (CSP) for HPLC was prepared by bonding (R)-1-phenyl-2-(4-methylphenyl)ethylamine amide derivative of (S)-valine to aminopropyl silica gel through a 2-amino-3,5-dinitro-1-carboxamido-benzene unit. The CSP was used for the separation of some amino acid derivatives and pyrethroid insecticides by chiral HPLC. Satisfactory baseline separation required optimization of the variables of mobile phase composition. Use of dichloromethane as modifier in the mobile phase gave baseline separations of amino acid derivatives. The two enantiomers of fenpropathrin and four stereoisomers of fenvalerate were baseline separated using hexane-dichloromethane-ethanol as mobile phase. The results show that the enantioselectivity of the new CSP is better than Pirkle type 1-A column for these compounds. Only partial separations were observed for the stereoisomers of cypermethrin and cyfluthrin, which gave even and eight peaks, respectively.

  14. Blind Separation of Acoustic Signals Combining SIMO-Model-Based Independent Component Analysis and Binary Masking

    Directory of Open Access Journals (Sweden)

    Hiekata Takashi

    2006-01-01

    Full Text Available A new two-stage blind source separation (BSS method for convolutive mixtures of speech is proposed, in which a single-input multiple-output (SIMO-model-based independent component analysis (ICA and a new SIMO-model-based binary masking are combined. SIMO-model-based ICA enables us to separate the mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources in their original form at the microphones. Thus, the separated signals of SIMO-model-based ICA can maintain the spatial qualities of each sound source. Owing to this attractive property, our novel SIMO-model-based binary masking can be applied to efficiently remove the residual interference components after SIMO-model-based ICA. The experimental results reveal that the separation performance can be considerably improved by the proposed method compared with that achieved by conventional BSS methods. In addition, the real-time implementation of the proposed BSS is illustrated.

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

    Directory of Open Access Journals (Sweden)

    Fumitoshi Yagishita

    2013-11-01

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

  16. Clustering Algorithm for Unsupervised Monaural Musical Sound Separation Based on Non-negative Matrix Factorization

    Science.gov (United States)

    Park, Sang Ha; Lee, Seokjin; Sung, Koeng-Mo

    Non-negative matrix factorization (NMF) is widely used for monaural musical sound source separation because of its efficiency and good performance. However, an additional clustering process is required because the musical sound mixture is separated into more signals than the number of musical tracks during NMF separation. In the conventional method, manual clustering or training-based clustering is performed with an additional learning process. Recently, a clustering algorithm based on the mel-frequency cepstrum coefficient (MFCC) was proposed for unsupervised clustering. However, MFCC clustering supplies limited information for clustering. In this paper, we propose various timbre features for unsupervised clustering and a clustering algorithm with these features. Simulation experiments are carried out using various musical sound mixtures. The results indicate that the proposed method improves clustering performance, as compared to conventional MFCC-based clustering.

  17. The Calculation of Collision Risk on Air-Routes Based on Variable Nominal Separation

    Institute of Scientific and Technical Information of China (English)

    QU Yu-ling; HAN Song-chen

    2010-01-01

    In this paper, a new method to calculate collision risk of air-routes, based on variable nominal separation, is proposed. The collision risk model of air-routes, based on the time variable and initial time interval variable, is given. Because the distance and the collision probability vary with time when the nominal relative speed between aircraft is not zero for a fixed initial time interval, the distance, the variable nominal separation, and the collision probability at any time can be expressed as functions of time and initial time interval. By the probabilistic theory, a model for calculating collision risk is acquired based on initial time interval distribution, flow rates, and the proportion of aircraft type. From the results of calculations, the collision risk can be characterized by the model when the nominal separation changes with time. As well the roles of parameters can be shown more readily.

  18. An advanced hybrid reprocessing system based on UF6 volatilization and chromatographic separation

    International Nuclear Information System (INIS)

    To recover U, Pu, MA (Np, Am, Cm) and some specific fission products FPs (Cs, Sr, Tc, etc.) from various spent nuclear fuels (LWR/FBR: Oxide, Metal Fuels), we are studying an advanced hybrid reprocessing system based on UF6 volatilization (Pyro) and chromatographic separation (Aqueous). Spent fuels are de-cladded by means of thermal and mechanical methods and then applied to the fluorination/volatilization process, which selectively recovers the most amount of U. Then, the remained fuel components are converted to oxides and dissolved by HNO3 solution. Compared to U, since Pu, MA and FPs are significantly less abundant in spent fuels, the scale of the aqueous separation process could become reasonably small and result in less waste. For the chromatographic separation processes, we have prepared different types of porous silica-based organic/inorganic adsorbents with fast diffusion kinetics, improved chemical stability and low pressure drop in a packed column. So they are advantageously applicable to efficient separation of the actinides and FP elements from the fuel dissolved solution. In this work, adsorption and separation behavior of representative actinides and FP elements was studied. Small scale separation tests using simulated and genuine fuel dissolved solutions were carried out to verify the feasibility of the proposed process. (authors)

  19. Interfacing Capillary-Based Separations to Mass Spectrometry Using Desorption Electro-spray Ionization

    International Nuclear Information System (INIS)

    The powerful hybrid analysis method of capillary-based separations followed by mass spectrometric analysis gives substantial chemical identity and structural information. It is usually carried out using electro-spray ionization. However, the salts and detergents used in the mobile phase for electrokinetic separations suppress ionization efficiencies and contaminate the inlet of the mass spectrometer. This report describes a new method that uses desorption electro-spray ionization (DESI) to overcome these limitations. Effluent from capillary Columns is deposited on a rotating Teflon disk that is covered with paper. As the surface rotates, the temporal separation of the eluting analytes (i.e., the electro-pherogram) is spatially encoded on the surface. Then, using DESI, surface-deposited analytes are preferentially ionized, reducing the effects of ion suppression and inlet contamination on signal. With the use of this novel approach, two capillary-based separations were performed; a mixture of the rhodamine dyes at milligram/milliliter levels in a 10 mM sodium borate solution was separated by capillary electrophoresis, and a mixture of three cardiac drugs at milligram/milliliter levels in a 12.5 mM sodium borate and 12.5 mM sodium dodecyl sulfate solution was separated by micellar electrokinetic chromatography. In both experiments, the negative effects of detergents and salts on the MS analyses were minimized. (authors)

  20. Slow magnetic relaxation in four square-based pyramidal dysprosium hydroxo clusters ligated by chiral amino acid anions - a comparative study.

    Science.gov (United States)

    Thielemann, Dominique T; Wagner, Anna T; Lan, Yanhua; Anson, Christopher E; Gamer, Michael T; Powell, Annie K; Roesky, Peter W

    2013-10-01

    The synthesis and characterization of three chiral and one achiral amino acid anion ligated dysprosium hydroxo clusters [Dy5(OH)5(α-AA)4(Ph2acac)6] (α-AA = d-PhGly, l-Pro, l-Trp, Ph2Gly; Ph2acac = dibenzoylmethanide) are reported. The solid state structures were determined using single crystal X-ray diffraction and show that five Dy(iii) ions are arranged in a square-based pyramidal geometry with NO7-donor-sets for the basal and O8-donor-sets for the apical Dy atom. Both static (dc) and dynamic (ac) magnetic properties were investigated for all four compounds and show a slow relaxation of magnetization, indicative of single molecule magnet (SMM) behaviour below 10 K in all cases. The similar SMM behaviour observed for all four compounds suggests that the very similar coordination geometries seen for the dysprosium atoms in all members of this family, which are independent of the amino acid ligand used, play a decisive role in steering the contribution of the single ion anisotropies to the observed magnetic relaxation. PMID:23986134

  1. Portable, Constriction-Expansion Blood Plasma Separation and Polymerization-Based Malaria Detection.

    Science.gov (United States)

    Shatova, Tatyana A; Lathwal, Shefali; Engle, Marissa R; Sikes, Hadley D; Jensen, Klavs F

    2016-08-01

    A portable, microfluidic blood plasma separation device is presented featuring a constriction-expansion design, which produces 100.0% purity for undiluted blood at 9% yield. This level of purity represents an improvement of at least 1 order of magnitude with increased yield compared to that achieved previously using passive separation. The system features high flow rates, 5-30 μL/min plasma collection, with minimal clogging and biofouling. The simple, portable blood plasma separation design is hand-driven and can easily be incorporated with microfluidic or laboratory scale diagnostic assays. The separation system was applied to a paper-based diagnostic test for malaria that produced an amplified color change in the presence of Plasmodium falciparum histidine-rich protein 2 at a concentration well below clinical relevancy for undiluted whole blood. PMID:27366819

  2. Blind Separation of Two Users Based on User Delays and Optimal Pulse-Shape Design

    Directory of Open Access Journals (Sweden)

    Poor HVincent

    2010-01-01

    Full Text Available A wireless network is considered, in which two spatially distributed users transmit narrow-band signals simultaneously over the same channel using the same power. User separation is achieved by oversampling the received signal and formulating a virtual multiple-input multiple-output (MIMO system based on the resulting polyphase components. Because of oversampling, high correlations can occur between the columns of the virtual MIMO system matrix which can be detrimental to user separation. A novel pulse-shape waveform design is proposed that results in low correlation between the columns of the system matrix, while it exploits all available bandwidth as dictated by a spectral mask. It is also shown that the use of successive interference cancelation in combination with blind source separation further improves the separation performance.

  3. Theory of ion-chirality relation in ferroelectric liquid crystals

    Science.gov (United States)

    Lahiri, T.; Pal Majumder, T.

    2012-04-01

    The presence of impurity ions in ferroelectric liquid crystals (FLC) could produce a significant impact on the chirality of the medium with a possible modification in the polarization profile of the system. We theoretically observed these possibilities by considering an in-plane and bulk free energy density for the sample. Based on a suitable chirality transfer formalism, we explained the role of impurity ions in altering the chiral nature of a FLC medium. A continuous transition from modulated phases to uniform phases is also predicted within the framework of this theory. Then, we investigated the possible modification in the polarization profile driven by ionic impurities.

  4. Examining a possible cascade effect in chiral symmetry breaking

    CERN Document Server

    Fariborz, Amir H

    2016-01-01

    We examine a toy model and a cascade effect for confinement and chiral symmetry breaking which consists in several phase transitions corresponding to the formation of bound states and chiral condensates with different number of fermions for a strong group. We analyze two examples: regular QCD where we calculate the "four quark" vacuum condensate and a preon composite model based on QCD at higher scales. In this context we also determine the number of flavors at which the second chiral and confinement phase transitions occur and discuss the consequences.

  5. Volume based vs. time based chromatograms: reproducibility of data for gradient separations under high and low pressure conditions.

    Science.gov (United States)

    Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Vajda, Péter; Beaver, Lois Ann; Guiochon, Georges

    2014-05-23

    A critical aspect in fast gradient separations carried out under constant pressure, in the very high pressure liquid chromatography (VHPLC) mode is that time-based chromatograms may not yield highly reproducible separations. A proposed solution to improve the reproducibility of these separations involves plotting the chromatograms as functions of the volume eluted vs. UV absorbance instead of time vs. UV. To study the consequences of using the volume-based rather than the time-based chromatograms, separations were first performed under low pressures that do not generate significant amounts of heat and for which the variations of the eluent density along the columns are negligible. Secondly, they were performed under very high pressures that do generate heat and measurable variations of the local retention factor and eluent density along the column. Comparison of the results provides estimates of the improvements obtained when volume based chromatograms are used in gradient analyses. Using a column packed with fully porous particles, four different types of methods and several sets for each method were used to perform the gradient elution runs: two sets of constant flow rate operations, four sets of constant pressure operations, two sets of constant pressure operations with programmed flow rate, and one set using the constant heat loss approach. The differences between time-based and volume-based chromatograms are demonstrated by using eight replicates of early, middle, and last eluting peaks. The results show that volume-based chromatograms improve the retention time reproducibility of the four constant pressure methods by a factor of 3.7 on average. If the column is not thermally conditioned prior to performing a long series of separations, flow controlled methods (constant flow rate, programmed constant pressure, and constant wall heat approaches) are more precise. If one gradient run is used to bring the column to a relatively stable temperature, constant

  6. Chiral Crystal Growth under Grinding

    OpenAIRE

    Saito, Yukio; Hyuga, Hiroyuki

    2008-01-01

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

  7. Spiral Galaxies as Chiral Objects?

    CERN Document Server

    Capozziello, S; Capozziello, Salvatore; Lattanzi, Alessandra

    2005-01-01

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

  8. Chiral dynamics and baryon resonances

    OpenAIRE

    Hyodo, Tetsuo

    2010-01-01

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

  9. A Chiral Granular Gas

    Science.gov (United States)

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

    2005-05-01

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

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

    OpenAIRE

    Menéndez, J.; Gazit, D.; Schwenk, A.

    2011-01-01

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

  11. Inversion of Supramolecular Chirality by Sonication-Induced Organogelation

    Science.gov (United States)

    Maity, Sibaprasad; Das, Priyadip; Reches, Meital

    2015-11-01

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

  12. ANALYSIS OF THE ENANTIOMERS OF CHIRAL PESTICIDES AND OTHER POLLUTANTS IN ENVIRONMENTAL SAMPLES BY CAPILLARY ELECTROPHORESIS

    Science.gov (United States)

    The generic method described here involves typical capillary electrophoresis (CE) techniques, with the addition of cyclodextrin chiral selectors to the electrolyte for enantiomer separation and also, in the case of neutral analytes, the further addition of a micelle forming comp...

  13. Generalized simplicial chiral models

    CERN Document Server

    Alimohammadi, M

    2000-01-01

    Using the auxiliary field representation of the simplicial chiral models on a (d-1)-dimensional simplex, we generalize the simplicial chiral models by replacing the term Tr$(AA^{\\d})$ in the Lagrangian of these models, by an arbitrary class function of $AA^{\\d}; V(AA^{\\d})$. This is the same method that has been used in defining the generalized two-dimensional Yang-Mills theories (gYM_2) from ordinary YM_2. We call these models, the " generalized simplicial chiral models ". With the help of the results of one-link integral over a U(N) matrix, we compute the large-N saddle-point equations for eigenvalue density function $\\ro (z)$ in the weak ($\\b >\\b_c$) and strong ($\\b <\\b_c$) regions. In d=2, where the model somehow relates to gYM_2 theory, we solve the saddle-point equations and find $\\ro (z)$ in two region, and calculate the explicit value of critical point $\\b_c$ for $V(B)=TrB^n (B=AA^{\\d})$. For $V(B)=Tr B^2,Tr B^3$ and Tr$B^4$, we study the critical behaviour of the model at d=2, and by calculating t...

  14. Chiral nuclear thermodynamics

    CERN Document Server

    Fiorilla, Salvatore; Weise, Wolfram

    2011-01-01

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

  15. The chiral magnetic effect in hydrodynamical approach

    OpenAIRE

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

    2010-01-01

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

  16. Heat-Flow-Driven Oligonucleotide Gelation Separates Single-Base Differences.

    Science.gov (United States)

    Morasch, Matthias; Braun, Dieter; Mast, Christof B

    2016-06-01

    DNA phase transitions are often induced by the addition of condensation agents or by dry concentration. Herein, we show that the non-equilibrium setting of a moderate heat flow across a water-filled chamber separates and gelates DNA strands with single-base resolution. A dilute mix of DNA with two slightly different gel-forming sequences separates into sequence-pure hydrogels under constant physiological solvent conditions. A single base change in a 36 mer DNA inhibits gelation. Only sequences with the ability to form longer strands are concentrated, further elongated, and finally gelated by length-dependent thermal trapping. No condensation agents, such as multivalent ions, were added. Equilibrium aggregates from dry concentration did not show any sequence separation. RNA is expected to behave identically owing to its equal thermophoretic properties. The highly sequence-specific phase transition points towards new possibilities for non-equilibrium origins of life. PMID:27060490

  17. Blind separation of sources in nonlinear convolved mixture based on a novel network

    Institute of Scientific and Technical Information of China (English)

    胡英; 杨杰; 沈利

    2004-01-01

    Blind separation of independent sources from their nonlinear convoluted mixtures is a more realistic problem than from linear ones. A solution to this problem based on the Entropy Maximization principle is presented. First we propose a novel two-layer network as the de-mixing system to separate sources in nonlinear convolved mixture. In output layer of our network we use feedback network architecture to cope with convoluted mixtures. Then we derive learning algorithms for the two-layer network by maximizing the information entropy. Based on the comparison of the computer simulation results, it can be concluded that the proposed algorithm has a better nonlinear convolved blind signal separation effect than the H.H. Y' s algorithm.

  18. Blind source separation of ship-radiated noise based on generalized Gaussian model

    Institute of Scientific and Technical Information of China (English)

    Kong Wei; Yang Bin

    2006-01-01

    When the distribution of the sources cannot be estimated accurately, the ICA algorithms failed to separate the mixtures blindly. The generalized Gaussian model (GGM) is presented in ICA algorithm since it can model nonGaussian statistical structure of different source signals easily. By inferring only one parameter, a wide class of statistical distributions can be characterized. By using maximum likelihood (ML) approach and natural gradient descent, the learning rules of blind source separation (BSS) based on GGM are presented. The experiment of the ship-radiated noise demonstrates that the GGM can model the distributions of the ship-radiated noise and sea noise efficiently, and the learning rules based on GGM gives more successful separation results after comparing it with several conventional methods such as high order cumulants and Gaussian mixture density function.

  19. Jammer Suppression in DS-CDMA Communications using Parafac-based Blind Separation

    Directory of Open Access Journals (Sweden)

    Xu Lingyun

    2016-01-01

    Full Text Available In this paper we propose to apply parafac-based source separation techniques for jammer suppression in direct spread spectrum communication systems. The jammer excision is formulated as an optimization problem and a new algorithm is presented which is based on the parafac tri-iterative least square algorithm. By jointly diagonalizing the time delay correlation matrix of the observed signals and using the new proposed method, a better solution is achieved. The proposed algorithm can successfully separate communication signals and jamming signals. Simulation results reveal that our proposed algorithm has the better blind signal separation performance than joint diagonalization method. Our proposed algorithm doesn’t require whitening processing. Moreover our proposed algorithm works well in the underdetermined condition, where the number of sources exceeds than the number of antennas.

  20. Fully automated objective-based method for master recession curve separation.

    Science.gov (United States)

    Posavec, Kristijan; Parlov, Jelena; Nakić, Zoran

    2010-01-01

    The fully automated objective-based method for master recession curve (MRC) separation was developed by using Microsoft Excel spreadsheet and Visual Basic for Applications (VBA) code. The core of the program code is used to construct an MRC by using the adapted matching strip method (Posavec et al. 2006). Criteria for separating the MRC into two or three segments are determined from the flow-duration curve and are represented as the probable range of percent of flow rate duration. Successive separations are performed automatically on two and three MRCs using sets of percent of flow rate duration from selected ranges and an optimal separation model scenario, having the highest average coefficient of determination R(2), is selected as the most appropriate one. The resulting separated master recession curves are presented graphically, whereas the statistics are presented numerically, all in separate sheets. Examples of field data obtained from two springs in Istria, Croatia, are used to illustrate its application. The freely available Excel spreadsheet and VBA program ensures the ease of use and applicability for larger data sets. PMID:20100291