WorldWideScience

Sample records for solvents chiral chemicals

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

    Directory of Open Access Journals (Sweden)

    Michiya Fujiki

    2014-08-01

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

  2. Solvent polarity effects on supramolecular chirality of a polyfluorene-thiophene copolymer.

    Science.gov (United States)

    Hirahara, Takashi; Yoshizawa-Fujita, Masahiro; Takeoka, Yuko; Rikukawa, Masahiro

    2018-06-01

    This study demonstrates the supramolecular chirality control of a conjugated polymer via solvent polarity. We designed and synthesized a chiral polyfluorene-thiophene copolymer having two different chiral side chains at the 9-position of the fluorene unit. Chiral cyclic and alkyl ethers with different polarities were selected as the chiral side chains. The sign of the circular dichroism spectra in the visible wavelength region was affected by the solvent system, resulting from the change of supramolecular structure. The estimation of the solubility parameter revealed that the solubility difference of the side chains contributed to the change of the circular dichroism sign, which was also observed in spin-coated films prepared from good solvents having different polarities. © 2018 Wiley Periodicals, Inc.

  3. Asymmetric Baylis-Hillman Reaction between Chiral Activated Alkenes and Aromatic Aldehydes in Me3N/H2O/Solvent Medium

    Institute of Scientific and Technical Information of China (English)

    Ke HE; Zheng Hong ZHOU; Hong Ying TANG; Guo Feng ZHAO; Chu Chi TANG

    2005-01-01

    Chiral activated alkene, L-menthyl acrylate and (+)-N-α-phenylethyl acrylamide,induced asymmetric Baylis-Hillman reaction of aromatic aldehydes was realized at 25℃ for 7 days in Me3N/H2O/solvent homogeneous medium. The corresponding Baylis-Hillman adducts were obtained in good chemical yield with moderate to excellent diastereoselectivity (up to 99% de).

  4. Chemical reactions in solvents and melts

    CERN Document Server

    Charlot, G

    1969-01-01

    Chemical Reactions in Solvents and Melts discusses the use of organic and inorganic compounds as well as of melts as solvents. This book examines the applications in organic and inorganic chemistry as well as in electrochemistry. Organized into two parts encompassing 15 chapters, this book begins with an overview of the general properties and the different types of reactions, including acid-base reactions, complex formation reactions, and oxidation-reduction reactions. This text then describes the properties of inert and active solvents. Other chapters consider the proton transfer reactions in

  5. Two-color QCD with non-zero chiral chemical potential

    Energy Technology Data Exchange (ETDEWEB)

    Braguta, V.V. [Institute for High Energy Physics NRC “Kurchatov Institute' ,142281 Protvino (Russian Federation); Far Eastern Federal University, School of Biomedicine,690950 Vladivostok (Russian Federation); Goy, V.A. [Far Eastern Federal University, School of Natural Sciences,690950 Vladivostok (Russian Federation); Ilgenfritz, E.M. [Joint Institute for Nuclear Research,BLTP, 141980 Dubna (Russian Federation); Kotov, A.Yu. [Institute of Theoretical and Experimental Physics,117259 Moscow (Russian Federation); Molochkov, A.V. [Far Eastern Federal University, School of Biomedicine,690950 Vladivostok (Russian Federation); Müller-Preussker, M.; Petersson, B. [Humboldt-Universität zu Berlin, Institut für Physik,12489 Berlin (Germany)

    2015-06-16

    The phase diagram of two-color QCD with non-zero chiral chemical potential is studied by means of lattice simulation. We focus on the influence of a chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical staggered fermions without rooting. The dependences of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented. The critical temperature is observed to increase with increasing chiral chemical potential.

  6. Molecular Mobility of an Amorphous Chiral Pharmaceutical Compound: Impact of Chirality and Chemical Purity.

    Science.gov (United States)

    Viel, Quentin; Delbreilh, Laurent; Coquerel, Gérard; Petit, Samuel; Dargent, Eric

    2017-08-17

    A dielectric relaxation spectroscopy (DRS) study was performed to investigate the molecular mobility of amorphous chiral diprophylline (DPL). For this purpose, both racemic DPL and a single enantiomer of DPL were considered. After fast cooling from the melt at very low temperature (-140 °C), progressive heating below and above the glass transition (T g ≈ 37 °C) induces two secondary relaxations (γ- and δ-) and primary relaxations (α-) for both enantiomeric compositions. After chemical purification of our samples by means of cooling recrystallization, no γ-process could be detected by DRS. Hence, it was highlighted that the molecular mobility in the glassy state is influenced by the presence of theophylline (TPH), the main impurity in DPL samples. We also proved that the dynamic behavior of a single enantiomer and the racemic mixture of the same purified compound are quasi-identical. This study demonstrates that the relative stability and the molecular mobility of chiral amorphous drugs are strongly sensitive to chemical purity.

  7. [Chemical hazards when working with solvent glues].

    Science.gov (United States)

    Domański, Wojciech; Makles, Zbigniew

    2012-01-01

    Solvent glues are used in a wide variety of industries, e.g., textile, footwear and rubber. The problem of workers' exposure to solvent vapors is rarely tackled within the area of occupational safety and health in small and medium-sized enterprises. In order to assess exposure to solvents, organic solvents emitted by glues were identified in the samples of workplace air. The concentration of acetone, benzene, cyclohexane, ethylbenzene, n-hexane, methylcyclohexane, butyl acetate and toluene were determined. The obtained results evidenced the presence of cyclohexane, ethylbenzene, ethylcyclohexane, heptane, n-hexane, o-xylene, methylcyclohexane, methylcyclopentane, butyl acetate and toluene in workplace air. The concentration of those compounds in workplace air was low, usually below 0.15 of MAC. At some workstations the presence of benzene was also observed. Occupational risk was assessed at workstations where gluing took place. It showed that the risk at those workstations was medium or low.

  8. Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent

    Energy Technology Data Exchange (ETDEWEB)

    Delmau, L.H.

    2002-10-08

    This work was undertaken to optimize the solvent used in the Caustic Side Solvent Extraction (CSSX) process and to measure key chemical and physical properties related to its performance in the removal of cesium from the alkaline high-level salt waste stored in tanks at the Savannah River Site. The need to adjust the solvent composition arose from the prior discovery that the previous baseline solvent was supersaturated with respect to the calixarene extractant. The following solvent-component concentrations in Isopar{reg_sign} L diluent are recommended: 0.007 M calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) extractant, 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) phase modifier, and 0.003 M tri-n-octylamine (TOA) stripping aid. Criteria for this selection included BOBCalixC6 solubility, batch cesium distribution ratios (D{sub Cs}), calculated flowsheet robustness, third-phase formation, coalescence rate (dispersion numbers), and solvent density. Although minor compromises within acceptable limits were made in flowsheet robustness and solvent density, significant benefits were gained in lower risk of third-phase formation and lower solvent cost. Data are also reported for the optimized solvent regarding the temperature dependence of D{sub Cs} in extraction, scrubbing, and stripping (ESS); ESS performance on recycle; partitioning of BOBCalixC6, Cs-7SB, and TOA to aqueous process solutions; partitioning of organic anions; distribution of metals; solvent phase separation at low temperatures; solvent stability to elevated temperatures; and solvent density and viscosity. Overall, the technical risk of the CSSX process has been reduced by resolving previously identified issues and raising no new issues.

  9. Remarkable solvent-dependent excited-state chirality : A molecular modulator of circularly polarized luminescence

    NARCIS (Netherlands)

    van Delden, Richard A.; Huck, N.P.M.; Piet, J.J.; Warman, J.M.; Meskers, S.C.J.; Dekkers, H.P J M; Feringa, B.L.

    2003-01-01

    The photochemical control of ground- and excited-state chirality of (M)-cis-(1) and (P)-trans(2)-2-nitro-7-(dimethylamino)-9-(2',3'-dihydro-1'H-naphtho[2,1-b]-thiopyran-1'-ylidene)-9H-thioxanthene is described. It is shown that while ground state chirality can be controlled photochemically by

  10. Remarkable solvent-dependent excited-state chirality : a molecular modulator of circularly polarized luminescence

    NARCIS (Netherlands)

    Delden, van R.A.; Huck, H.P.M.; Piet, J.J.; Warman, J.M.; Meskers, S.C.J.; Dekkers, H.P.J.M.; Feringa, B.L.

    2003-01-01

    The photochemical control of ground- and excited-state chirality of (M)-cis-(1) and (P)-trans-(2)-2-nitro-7-(dimethylamino)-9-(2',3' -dihydro-1'H-naphtho[2,1-b]-thiopyran-1'-ylidene)-9H-thioxanthene is described. It is shown that while ground state chirality can be controlled photochemically by

  11. Developing new chemical tools for solvent extraction

    International Nuclear Information System (INIS)

    Moyer, B.A.; Baes, C.F.; Burns, J.H.; Case, G.N.; Sachleben, R.A.; Bryan, S.A.; Lumetta, G.J.; McDowell, W.J.; Sachleben, R.A.

    1993-01-01

    Prospects for innovation and for greater technological impact in the field of solvent extraction (SX) seem as bright as ever, despite the maturation of SX as an economically significant separation method and as an important technique in the laboratory. New industrial, environmental, and analytical problems provide compelling motivation for diversifying the application of SX, developing new solvent systems, and seeking improved properties. Toward this end, basic research must be dedicated to enhancing the tools of SX: physical tools for probing the basis of extraction and molecular tools for developing new SX chemistries. In this paper, the authors describe their progress in developing and applying the general tools of equilibrium analysis and of ion recognition in SX. Nearly half a century after the field of SX began in earnest, coordination chemistry continues to provide the impetus for important advancements in understanding SX systems and in controlling SX chemistry. In particular, the physical tools of equilibrium analysis, X-ray crystallography, and spectroscopy are elucidating the molecular basis of SX in unprecedented detail. Moreover, the principles of ion recognition are providing the molecular tools with which to achieve new selectivities and new applications

  12. Mirror-symmetry-breaking in poly[(9,9-di-n-octylfluorenyl- 2,7-diyl)-alt-biphenyl] (PF8P2) is susceptible to terpene chirality, achiral solvents, and mechanical stirring.

    Science.gov (United States)

    Fujiki, Michiya; Kawagoe, Yoshifumi; Nakano, Yoko; Nakao, Ayako

    2013-06-17

    Solvent chirality transfer of (S)-/(R)-limonenes allows the instant generation of optically active PF8P2 aggregates with distinct circular dichroism (CD)/circularly polarized luminescence (CPL) amplitudes with a high quantum yield of 16-20%. The present paper also reports subtle mirror-symmetry-breaking effects in CD-/CPL-amplitude and sign, CD/UV-vis spectral wavelengths, and photodynamics of the aggregates, though the reasons for the anomaly are unsolved. However, these photophysical properties depend on (i) the chemical natures of chiral and achiral molecules when used in solvent quantity, (ii) clockwise and counterclockwise stirring operations, and (iii) the order of addition of limonene and methanol to the chloroform solution.

  13. Mirror-Symmetry-Breaking in Poly[(9,9-di-n-octylfluorenyl-2,7-diyl-alt-biphenyl] (PF8P2 is Susceptible to Terpene Chirality, Achiral Solvents, and Mechanical Stirring

    Directory of Open Access Journals (Sweden)

    Ayako Nakao

    2013-06-01

    Full Text Available Solvent chirality transfer of (S-/(R-limonenes allows the instant generation of optically active PF8P2 aggregates with distinct circular dichroism (CD/circularly polarized luminescence (CPL amplitudes with a high quantum yield of 16–20%. The present paper also reports subtle mirror-symmetry-breaking effects in CD-/CPL-amplitude and sign, CD/UV-vis spectral wavelengths, and photodynamics of the aggregates, though the reasons for the anomaly are unsolved. However, these photophysical properties depend on (i the chemical natures of chiral and achiral molecules when used in solvent quantity, (ii clockwise and counterclockwise stirring operations, and (iii the order of addition of limonene and methanol to the chloroform solution.

  14. Chiral diamine-silver(I)-alkene complexes: a quantum chemical and NMR study

    DEFF Research Database (Denmark)

    Kieken, Elsa; Wiest, Olaf; Helquist, Paul

    2005-01-01

    explored by DFT methods. By successive substitution of the computational model complexes, it has been possible to elucidate the role of each amine substituent in achieving successful discrimination of alkenes. The conformational space has been fully explored using small model systems, allowing an unbiased......The ability of chiral diamine silver complexes to bind chiral and prochiral alkenes has been analyzed in detail. The stereoselectivity in binding of alkenes to a chiral ethanediamine silver complex has been investigated by NMR. The low-energy conformations of several small model complexes have been...... calculation of stereoselectivities that match well the experimental results. For a chiral allylic alcohol substrate, the correct stereoselectivity was obtained only when the structures were optimized with a continuum representation of the solvent. The discrepancy between gas phase and solution data is found...

  15. The chiral phase transition for two-flavour QCD at imaginary and zero chemical potential

    CERN Document Server

    Bonati, Claudio; de Forcrand, Philippe; Philipsen, Owe; Sanfillippo, Francesco

    2013-01-01

    The chiral symmetry of QCD with two massless quark flavours gets restored in a non-analytic chiral phase transition at finite temperature and zero density. Whether this is a first-order or a second-order transition has not yet been determined unambiguously, due to the difficulties of simulating light quarks. We investigate the nature of the chiral transition as a function of quark mass and imaginary chemical potential, using staggered fermions on N_t=4 lattices. At sufficiently large imaginary chemical potential, a clear signal for a first-order transition is obtained for small masses, which weakens with decreasing imaginary chemical potential. The second-order critical line m_c(mu_i), which marks the boundary between first-order and crossover behaviour, extrapolates to a finite m_c(mu_i=0) with known critical exponents. This implies a definitely first-order transition in the chiral limit on relatively coarse, N_t=4 lattices.

  16. 25 CFR 11.451 - Abuse of psychotoxic chemical solvents.

    Science.gov (United States)

    2010-04-01

    ... use the solvent in violation of this section. (b) This section does not apply to inhalation of... any glue, gasoline, paint, hair spray, Lysol, or other substance containing one or more of the...) Peptone; (7) Pentachlorophenol; (8) Petroleum ether; or (9) Any other chemical substance the inhalation of...

  17. Secondary cleanup of Idaho Chemical Processing Plant solvent

    International Nuclear Information System (INIS)

    Mailen, J.C.

    1985-01-01

    Solvent from the Idaho Chemical Processing Plant (ICPP) (operated by Westinghouse Idaho Nuclear Company, Inc.) has been tested to determine the ability of activated alumina to remove secondary degradation products - those degradation products which are not removed by scrubbing with sodium carbonate

  18. Stability of racemic and chiral steady states in open and closed chemical systems

    Energy Technology Data Exchange (ETDEWEB)

    Ribo, Josep M. [Departament de Quimica Organica, Universitat de Barcelona, c. Marti i Franques 1, Barcelona (Spain); Hochberg, David [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir Km. 4, 28850 Torrejon de Ardoz, Madrid (Spain)], E-mail: hochbergd@inta.es

    2008-12-22

    The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived.

  19. Stability of racemic and chiral steady states in open and closed chemical systems

    International Nuclear Information System (INIS)

    Ribo, Josep M.; Hochberg, David

    2008-01-01

    The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived

  20. Stirring competes with chemical induction in chiral selection of Langmuir monolayer domains

    Directory of Open Access Journals (Sweden)

    Petit-Garrido Nuria

    2013-08-01

    Full Text Available Chirality, the absence of mirror symmetry, can be equally invoked in relation to physical forces and chemical induction processes, yet a competition between these two types of influences is rarely reported. Here, we employ Langmuir monolayers of azobenzene surfactants as a prototypical self-assembled two-dimensional system in which chiral selection is controlled by the combined independent action of a chiral dopant and vortical stirring. The two effects can be arbitrarily coupled, either constructively or destructively, leading to a situation of perfect compensation. The induced enantiomorphic excess is measured in terms of the statistical imbalance of an ensemble of sub-millimeter monolayer domains, where achiral molecules self-assemble with a well-defined orientational chirality, which is unambiguously resolved using Brewster angle microscopy.

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

    Czech Academy of Sciences Publication Activity Database

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

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

  3. Quantification of simultaneous solvent evaporation and chemical curing in thermoset coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2010-01-01

    The mechanisms of simultaneous solvent evaporation and film formation in high-solids thermoset coatings are considered. The relevant phenomena, chemical reactions, solvent diffusion and evaporation, gelation, vitrification, network mobility restrictions, and crosslinking, are quantified and a mat...

  4. Chiral condensate at nonzero chemical potential in the microscopic limit of QCD

    International Nuclear Information System (INIS)

    Osborn, J. C.; Splittorff, K.; Verbaarschot, J. J. M.

    2008-01-01

    The chiral condensate in QCD at zero temperature does not depend on the quark chemical potential (up to one-third the nucleon mass), whereas the spectral density of the Dirac operator shows a strong dependence on the chemical potential. The cancellations which make this possible also occur on the microscopic scale, where they can be investigated by means of a random matrix model. We show that they can be understood in terms of orthogonality properties of orthogonal polynomials. In the strong non-Hermiticity limit they are related to integrability properties of the spectral density. As a by-product we find exact analytical expressions for the partially quenched chiral condensate in the microscopic domain at nonzero chemical potential.

  5. The chiral phase transition in two-flavor QCD from imaginary chemical potential

    CERN Document Server

    Bonati, Claudio; D'Elia, Massimo; Philipsen, Owe; Sanfilippo, Francesco

    2014-01-01

    We investigate the order of the finite temperature chiral symmetry restoration transition for QCD with two massless fermions, by using a novel method, based on simulating imaginary values of the quark chemical potential $\\mu=i\\mu_i,\\mu_i\\in\\mathbb{R}$. Our method exploits the fact that, for low enough quark mass $m$ and large enough chemical potential $\\mu_i$, the chiral transition is decidedly first order, then turning into crossover at a critical mass $m_c(\\mu)$. It is thus possible to determine the critical line in the $m - \\mu^2$ plane, which can be safely extrapolated to the chiral limit by taking advantage of the known tricritical indices governing its shape. We test this method with standard staggered fermions and the result of our simulations is that $m_c(\\mu=0)$ is positive, so that the phase transition at zero density is definitely first order in the chiral limit, on our coarse $N_t=4$ lattices with $a\\simeq 0.3\\,\\mathrm{fm}$.

  6. Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

    Directory of Open Access Journals (Sweden)

    Ayman L. Hemasa

    2017-07-01

    Full Text Available Carbon nanotubes (CNTs possess unique mechanical, physical, electrical and absorbability properties coupled with their nanometer dimensional scale that renders them extremely valuable for applications in many fields including nanotechnology and chromatographic separation. The aim of this review is to provide an updated overview about the applications of CNTs in chiral and achiral separations of pharmaceuticals, biologics and chemicals. Chiral single-walled carbon nanotubes (SWCNTs and multi-walled carbon nanotubes (MWCNTs have been directly applied for the enantioseparation of pharmaceuticals and biologicals by using them as stationary or pseudostationary phases in chromatographic separation techniques such as high-performance liquid chromatography (HPLC, capillary electrophoresis (CE and gas chromatography (GC. Achiral MWCNTs have been used for achiral separations as efficient sorbent objects in solid-phase extraction techniques of biochemicals and drugs. Achiral SWCNTs have been applied in achiral separation of biological samples. Achiral SWCNTs and MWCNTs have been also successfully used to separate achiral mixtures of pharmaceuticals and chemicals. Collectively, functionalized CNTs have been indirectly applied in separation science by enhancing the enantioseparation of different chiral selectors whereas non-functionalized CNTs have shown efficient capabilities for chiral separations by using techniques such as encapsulation or immobilization in polymer monolithic columns.

  7. Improvement of solvents for chemical decontamination: nickel ferrites removal

    International Nuclear Information System (INIS)

    Figueroa, Carlos A.; Morando, Pedro J.; Blesa, Miguel A.

    1999-01-01

    Carboxylic acids are usually included in commercial solvents for the chemical cleaning and decontamination of metal surfaces from the oxide layers grown and/or deposited from high temperature water by corrosive process. In particular oxalic acid is included in second path of AP-Citrox method. However, in some cases, their use shows low efficiency. This fact is attributed to the special passivity of the mixed oxides as nickel ferrites. This work reports a kinetic study of dissolution of a synthetic nickel ferrite (NiFe 2 O 4 ) confronted with simple oxides (NiO and Fe 2 O 3 ) in mineral acids and oxalic acid. The dissolution factor and reaction rate were determined in several conditions (reactive concentrations, pH and added ferrous ions). Experimental data of dissolution (with and without Fe(II) added) show a congruent kinetic regime. Pure nickel oxide (NiO) is rather resistant to the attack by oxalic acid solutions, and ferrous ions do not accelerate dissolution. In fact, nickel oxide dissolves better by oxidative attack that takes advantage of the higher lability of Ni 3+ . It may be concluded that oxalic acid operates to dissolve iron, and the ensuing disruption of the solid framework accelerates the release of nickel. Our results point to use more reactive solvents in iron from mixed oxides and to the possibility of using one stage decontamination method. (author)

  8. Chemical and radiolytical solvent degradation in the Purex process

    International Nuclear Information System (INIS)

    Stieglitz, L.; Becker, R.

    1985-01-01

    The state of the art of chemical and radiolytical solvent degradation is described. For the hydrolysis of tributylphosphate TBP->HDBP->H 2 MBP->H 3 PO 4 values are given for the individual constants in a temperature range from 23 to 90 0 C. Radiolytic yields were measured for HDBP as 80 mg/Wh, for H 2 MBP as 2 mg/Wh, and for H 3 PO 4 as 5 mg/Wh. Experimental results on the degradation products of the diluent are summarized and their influence on the process is discussed. Long chain acid phosphates and acid TBP oligomeres were identified as responsible for the retention of fission products. Techniques such as polarography, infrared spectrometry and electrolytic conductometry are applied to estimate concentrations of degradation products down to 10 -5 mol/l. (orig.) [de

  9. Chemical and radiolytical solvent degradation in the Purex process

    Energy Technology Data Exchange (ETDEWEB)

    Stieglitz, L; Becker, R

    1985-01-01

    The state of the art of chemical and radiolytical solvent degradation is described. For the hydrolysis of tributylphosphate TBP->HDBP->H/sub 2/MBP->H/sub 3/PO/sub 4/ values are given for the individual constants in a temperature range from 23 to 90/sup 0/C. Radiolytic yields were measured for HDBP as 80 mg/Wh, for H/sub 2/MBP as 2 mg/Wh, and for H/sub 3/PO/sub 4/ as 5 mg/Wh. Experimental results on the degradation products of the diluent are summarized and their influence on the process is discussed. Long chain acid phosphates and acid TBP oligomeres were identified as responsible for the retention of fission products. Techniques such as polarography, infrared spectrometry and electrolytic conductometry are applied to estimate concentrations of degradation products down to 10/sup -5/ mol/l.

  10. Polymer optical fiber tapering using chemical solvent and polishing

    Science.gov (United States)

    Supian, L. S.; Syuhaimi Ab-Rahman, Mohd; Arsad, Norhana

    2017-11-01

    A method for developing polymer optical fiber (POF) directional coupler is introduced where the initial procedure includes using chemical solvent to remove the cladding, and bare out the core in order to align the unclad center of the fiber with other similar fiber to develop a coupler. The process is safe, simple, inexpensive and require low operation skill. The etched fiber offers improvement to the performance of various POF devices, i.e, couplers and sensors. Instead of relying only on silica or glass fiber, POF now can be used as an alternative to improve the network performance in short distance communication system. The measurement parameters laid out offer great outcomes. However, the couplers intended to be developed is yet to be realized, where deeper research and various experiments are needed in order to develop a simple but optimum performance coupler that can be used for various applications.

  11. Polymer optical fiber tapering using chemical solvent and polishing

    Directory of Open Access Journals (Sweden)

    Supian L. S.

    2017-01-01

    Full Text Available A method for developing polymer optical fiber (POF directional coupler is introduced where the initial procedure includes using chemical solvent to remove the cladding, and bare out the core in order to align the unclad center of the fiber with other similar fiber to develop a coupler. The process is safe, simple, inexpensive and require low operation skill. The etched fiber offers improvement to the performance of various POF devices, i.e, couplers and sensors. Instead of relying only on silica or glass fiber, POF now can be used as an alternative to improve the network performance in short distance communication system. The measurement parameters laid out offer great outcomes. However, the couplers intended to be developed is yet to be realized, where deeper research and various experiments are needed in order to develop a simple but optimum performance coupler that can be used for various applications.

  12. Synthesis of chiral polyaniline films via chemical vapor phase polymerization

    DEFF Research Database (Denmark)

    Chen, J.; Winther-Jensen, B.; Pornputtkul, Y.

    2006-01-01

    Electrically and optically active polyaniline films doped with (1)-(-)-10- camphorsulfonic acid were successfully deposited on nonconductive substrates via chemical vapor phase polymerization. The above polyaniline/ R- camphorsulfonate films were characterized by electrochemical and physical...

  13. Chemical engineering aspect of solvent extraction in mineral processing

    International Nuclear Information System (INIS)

    Dara, S.S.; Jakkikar, M.S.

    1975-01-01

    Solvent extraction process, types of solvents used, types of extraction, distribution isotherm and McCabe-Thiele diagram for process design, equipment for the process, operating parameters and applications are described. (M.G.B.)

  14. Enantiomeric profiling of a chemically diverse mixture of chiral pharmaceuticals in urban water

    International Nuclear Information System (INIS)

    Evans, S.; Bagnall, J.; Kasprzyk-Hordern, B.

    2017-01-01

    . - Highlights: • Chiral drugs present in wastewater and receiving waters enriched with one enantiomeric form. • Stereoselective microbial degradation observed in receiving water and activated sludge microcosms. • Preferential degradation of S(+)-, R(+)- & S(+)- amphetamines, beta-blockers & antidepressants respectively. • Desmethyl metabolites showed higher degradation rate and stereoselectivity. • Metabolites enriched with enantiomers of opposite configuration to their parent compounds. - Enantiomeric profiling of chemically diverse mixtures of chiral pharmaceuticals in urban water shows high stereoselectivity of environmental processes.

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

    Directory of Open Access Journals (Sweden)

    Janus Ewa

    2017-09-01

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

  16. Chiral separation of G-type chemical warfare nerve agents via analytical supercritical fluid chromatography.

    Science.gov (United States)

    Kasten, Shane A; Zulli, Steven; Jones, Jonathan L; Dephillipo, Thomas; Cerasoli, Douglas M

    2014-12-01

    Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G-type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical-scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(-) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(-) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents. © 2014 The Authors. Chirality published by John Wiley Periodicals, Inc.

  17. Chiral chromatography studies of chemical behavior of cinacalcet on polysaccharide chiral reversed-phase HPLC stationary phases.

    Science.gov (United States)

    Dousa, Michal; Brichác, Jirí

    2012-01-01

    A rapid HPLC method for the analytical resolution of cinacalcet enantiomers was developed. Four chiral columns (two amylose and two cellulose type) were evaluated in RP systems. Excellent enantioseparation with a resolution of more than 6 was achieved on Chiralpak AY (amylose 5-chloro-2-methylphenylcarbamate chiral stationary phase) using 10 mM triethylamine (pH 8.0)-acetonitrile (40 + 60, v/v) mobile phase. Validation of the HPLC method, including linearity, LOD, LOQ, precision, accuracy, and selectivity, was performed according to the International Conference on Harmonization guidelines. The method was successfully applied for the determination of (S)-cinacalcet in enantiopure active pharmaceutical ingredient (R)-cinacalcet.

  18. Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical-Chiral Sensors.

    Science.gov (United States)

    Ibanez, Jorge G; Rincón, Marina E; Gutierrez-Granados, Silvia; Chahma, M'hamed; Jaramillo-Quintero, Oscar A; Frontana-Uribe, Bernardo A

    2018-05-09

    Conducting polymers (CPs), thanks to their unique properties, structures made on-demand, new composite mixtures, and possibility of deposit on a surface by chemical, physical, or electrochemical methodologies, have shown in the last years a renaissance and have been widely used in important fields of chemistry and materials science. Due to the extent of the literature on CPs, this review, after a concise introduction about the interrelationship between electrochemistry and conducting polymers, is focused exclusively on the following applications: energy (energy storage devices and solar cells), use in environmental remediation (anion and cation trapping, electrocatalytic reduction/oxidation of pollutants on CP based electrodes, and adsorption of pollutants) and finally electroanalysis as chemical sensors in solution, gas phase, and chiral molecules. This review is expected to be comprehensive, authoritative, and useful to the chemical community interested in CPs and their applications.

  19. Chiral discrimination in nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Lazzeretti, Paolo

    2017-11-01

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

  20. Compound forming extractants, solvating solvents and inert solvents IUPAC chemical data series

    CERN Document Server

    Marcus, Y; Kertes, A S

    2013-01-01

    Equilibrium Constants of Liquid-Liquid Distribution Reactions, Part III: Compound Forming Extractants, Solvating Solvents, and Inert Solvents focuses on the compilation of equilibrium constants of various compounds, such as acids, ions, salts, and aqueous solutions. The manuscript presents tables that show the distribution reactions of carboxylic and sulfonic acid extractants and their dimerization and other reactions in the organic phase and extraction reactions of metal ions from aqueous solutions. The book also states that the inorganic anions in these solutions are irrelevant, since they d

  1. Control of Chemical Equilibrium by Solvent: A Basis for Teaching Physical Chemistry of Solutions

    Science.gov (United States)

    Prezhdo, Oleg V.; Craig, Colleen F.; Fialkov, Yuriy; Prezhdo, Victor V.

    2007-01-01

    The study demonstrates that the solvent present in a system can highly alter and control the chemical equilibrium of a system. The results show that the dipole moment and polarizibility of a system can be highly altered by using different mixed solvents.

  2. On the chiral perturbation theory for two-flavor two-color QCD at finite chemical potential

    Czech Academy of Sciences Publication Activity Database

    Brauner, Tomáš

    2006-01-01

    Roč. 21, č. 7 (2006), s. 559-569 ISSN 0217-7323 R&D Projects: GA ČR(CZ) GD202/05/H003 Institutional research plan: CEZ:AV0Z10480505 Keywords : two-color QCD * chiral perturbation theory * chemical potential Subject RIV: BE - Theoretical Physics Impact factor: 1.564, year: 2006

  3. A multi target approach to control chemical reactions in their inhomogeneous solvent environment

    International Nuclear Information System (INIS)

    Keefer, Daniel; Thallmair, Sebastian; Zauleck, Julius P P; Vivie-Riedle, Regina de

    2015-01-01

    Shaped laser pulses offer a powerful tool to manipulate molecular quantum systems. Their application to chemical reactions in solution is a promising concept to redesign chemical synthesis. Along this road, theoretical developments to include the solvent surrounding are necessary. An appropriate theoretical treatment is helpful to understand the underlying mechanisms. In our approach we simulate the solvent by randomly selected snapshots from molecular dynamics trajectories. We use multi target optimal control theory to optimize pulses for the various arrangements of explicit solvent molecules simultaneously. This constitutes a major challenge for the control algorithm, as the solvent configurations introduce a large inhomogeneity to the potential surfaces. We investigate how the algorithm handles the new challenges and how well the controllability of the system is preserved with increasing complexity. Additionally, we introduce a way to statistically estimate the efficiency of the optimized laser pulses in the complete thermodynamical ensemble. (paper)

  4. A QCD chiral critical point at small chemical potential: is it there or not?

    CERN Document Server

    de Forcrand, Philippe; Philipsen, Owe

    2007-01-01

    For a QCD chiral critical point to exist, the parameter region of small quark masses for which the finite temperature transition is first-order must expand when the chemical potential is turned on. This can be tested by a Taylor expansion of the critical surface (m_{u,d},m_s)_c(mu). We present a new method to perform this Taylor expansion numerically, which we first test on an effective model of QCD with static, dense quarks. We then present the results for QCD with 3 degenerate flavors. For a lattice with N_t=4 time-slices, the first-order region shrinks as the chemical potential is turned on. This implies that, for physical quark masses, the analytic crossover which occurs at mu=0 between the hadronic and the plasma regimes remains crossover in the mu-region where a Taylor expansion is reliable, i.e. mu less than or similar to T. We present preliminary results from finer lattices indicating that this situation persists, as does the discrepancy between the curvature of T_c(mu) and the experimentally observed...

  5. Chemical approach to solvent removal during nanoencapsulation: its application to preparation of PLGA nanoparticles with non-halogenated solvent

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngme [Ewha Womans University, College of Pharmacy (Korea, Republic of); Sah, Eric [University of Notre Dame, College of Science (United States); Sah, Hongkee, E-mail: hsah@ewha.ac.kr [Ewha Womans University, College of Pharmacy (Korea, Republic of)

    2015-11-15

    The objective of this study was to develop a new oil-in-water emulsion-based nanoencapsulation method for the preparation of PLGA nanoparticles using a non-halogenated solvent. PLGA (60–150 mg) was dissolved in 3 ml of methyl propionate, which was vortexed with 4 ml of a 0.5–4 % polyvinyl alcohol solution. This premix was sonicated for 2 min, added into 30 ml of the aqueous polyvinyl alcohol solution, and reacted with 3 ml of 10 N NaOH. Solvent removal was achieved by the alkaline hydrolysis of methyl propionate dissolved in an aqueous phase into water-soluble methanol and sodium propionate. It was a simple but effective technique to quickly harden nanoemulsion droplets into nanoparticles. The appearing PLGA nanoparticles were recovered by ultracentrifugation and/or dialysis, lyophilized with trehalose, and redispersed by water. This nanoencapsulation technique permitted a control of their mean diameters over 151.7 ± 3.8 to 440.2 ± 22.2 nm at mild processing conditions. When the aqueous polyvinyl alcohol concentration was set at ≥1 %, nanoparticles showed uniform distributions with polydispersity indices below 0.1. There were no significant changes in their mean diameters and size distribution patterns before and after lyophilization. When mestranol was encapsulated into nanoparticles, the drug was completely nanoencapsulated: depending on experimental conditions, their encapsulation efficiencies were determined to be 99.4 ± 7.2 to 105.8 ± 6.3 %. This simple, facile nanoencapsulation technique might have versatile applications for the preparation of polymeric nanoparticulate dosage forms.Graphical AbstractSchematic illustration of an innovative chemical approach to solvent removal during nanoencapsulation. Methyl propionate present in the aqueous continuous phase reacts with sodium hydroxide, thereby producing methanol and sodium propionate. Its alkaline hydrolysis allows the continuous extraction of the solvent out of nanoemulsion

  6. Chemical approach to solvent removal during nanoencapsulation: its application to preparation of PLGA nanoparticles with non-halogenated solvent

    International Nuclear Information System (INIS)

    Lee, Youngme; Sah, Eric; Sah, Hongkee

    2015-01-01

    The objective of this study was to develop a new oil-in-water emulsion-based nanoencapsulation method for the preparation of PLGA nanoparticles using a non-halogenated solvent. PLGA (60–150 mg) was dissolved in 3 ml of methyl propionate, which was vortexed with 4 ml of a 0.5–4 % polyvinyl alcohol solution. This premix was sonicated for 2 min, added into 30 ml of the aqueous polyvinyl alcohol solution, and reacted with 3 ml of 10 N NaOH. Solvent removal was achieved by the alkaline hydrolysis of methyl propionate dissolved in an aqueous phase into water-soluble methanol and sodium propionate. It was a simple but effective technique to quickly harden nanoemulsion droplets into nanoparticles. The appearing PLGA nanoparticles were recovered by ultracentrifugation and/or dialysis, lyophilized with trehalose, and redispersed by water. This nanoencapsulation technique permitted a control of their mean diameters over 151.7 ± 3.8 to 440.2 ± 22.2 nm at mild processing conditions. When the aqueous polyvinyl alcohol concentration was set at ≥1 %, nanoparticles showed uniform distributions with polydispersity indices below 0.1. There were no significant changes in their mean diameters and size distribution patterns before and after lyophilization. When mestranol was encapsulated into nanoparticles, the drug was completely nanoencapsulated: depending on experimental conditions, their encapsulation efficiencies were determined to be 99.4 ± 7.2 to 105.8 ± 6.3 %. This simple, facile nanoencapsulation technique might have versatile applications for the preparation of polymeric nanoparticulate dosage forms.Graphical AbstractSchematic illustration of an innovative chemical approach to solvent removal during nanoencapsulation. Methyl propionate present in the aqueous continuous phase reacts with sodium hydroxide, thereby producing methanol and sodium propionate. Its alkaline hydrolysis allows the continuous extraction of the solvent out of nanoemulsion

  7. Efficient Regeneration of Physical and Chemical Solvents for CO2 Capture

    Energy Technology Data Exchange (ETDEWEB)

    Tande, Brian [Univ. of North Dakota, Grand Forks, ND (United States); Seames, Wayne [Univ. of North Dakota, Grand Forks, ND (United States); Benson, Steve [Univ. of North Dakota, Grand Forks, ND (United States)

    2013-12-01

    The objective of this project was to evaluate the use of composite polymer membranes and porous membrane contactors to regenerate physical and chemical solvents for capture of carbon dioxide (CO2) from synthesis gas or flue gas, with the goal of improving the energy efficiency of carbon capture. Both a chemical solvent (typical for a post-combustion capture of CO2 from flue gas) and a physical solvent (typical for pre- combustion capture of CO2 from syngas) were evaluated using two bench-scale test systems constructed for this project. For chemical solvents, polytetrafluoroethylene and polypropylene membranes were found to be able to strip CO2 from a monoethanolamine (MEA) solution with high selectivity without significant degradation of the material. As expected, the regeneration temperature was the most significant parameter affecting the CO2 flux through the membrane. Pore size was also found to be important, as pores larger than 5 microns lead to excessive pore wetting. For physical solvents, polydimethyl-siloxane (PDMS)-based membranes were found to have a higher CO2 permeability than polyvinylalcohol (PVOH) based membranes, while also minimizing solvent loss. Overall, however, the recovery of CO2 in these systems is low – less than 2% for both chemical and physical solvents – primarily due to the small surface area of the membrane test apparatus. To obtain the higher regeneration rates needed for this application, a much larger surface area would be needed. Further experiments using, for example, a hollow fiber membrane module could determine if this process could be commercially viable.

  8. Caustic-Side Solvent Extraction Chemical and Physical Properties Progress in FY 2000 and FY 2001.

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, BA

    2002-04-17

    The purpose of this work was to provide chemical- and physical-property data addressing the technical risks of the Caustic-Side Solvent Extraction (CSSX) process as applied specifically to the removal of cesium from alkaline high-level salt waste stored at the US Department of Energy Savannah River Site. As part of the overall Salt Processing Project, this effort supported decision-making in regards to selecting a preferred technology among three alternatives: (1) CSSX, (2) nonelutable ion-exchange with an inorganic silicotitanate material and (3) precipitation with tetraphenylborate. High risks, innate to CSSX, that needed specific attention included: (1) chemical stability of the solvent matrix, (2) radiolytic stability of the solvent matrix, (3) proof-of-concept performance of the proposed process flowsheet with simulated waste, and (4) performance of the CSSX flowsheet with actual SRS high-level waste. This body of work directly addressed the chemical-stability risk and additionally provided supporting information that served to plan, carry out, and evaluate experiments conducted by other CSSX investigators addressing the other high risks. Information on cesium distribution in extraction, scrubbing, and stripping served as input for flowsheet design, provided a baseline for evaluating solvent performance under numerous stresses, and contributed to a broad understanding of the effects of expected process variables. In parallel, other measurements were directed toward learning how other system components distribute in the flowsheet. Such components include the solvent components themselves, constituents of the waste, and solvent-degradation products. Upon understanding which components influence flowsheet performance, it was then possible to address in a rational fashion how to clean up the solvent and maintain its stable function.

  9. Towards electron transport measurements in chemically modified graphene: effect of a solvent

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, Arnhild; Ensslin, Klaus [Solid State Physics Laboratory, ETH Zurich (Switzerland); Koehler, Fabian M; Stark, Wendelin J, E-mail: arnhildj@phys.ethz.ch, E-mail: fabian.koehler@chem.ethz.ch [Institute for Chemical and Bioengineering, ETH Zurich (Switzerland)

    2010-12-15

    The chemical functionalization of graphene modifies the local electron density of carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on electron transport. The latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that the solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport, which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look at the influence of solvents used for chemical modification in order to understand their influence.

  10. Towards electron transport measurements in chemically modified graphene: effect of a solvent

    International Nuclear Information System (INIS)

    Jacobsen, Arnhild; Ensslin, Klaus; Koehler, Fabian M; Stark, Wendelin J

    2010-01-01

    The chemical functionalization of graphene modifies the local electron density of carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on electron transport. The latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that the solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport, which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look at the influence of solvents used for chemical modification in order to understand their influence.

  11. NONPROCESS SOLVENT USE IN THE FURNITURE REFINISHING AND REPAIR INDUSTRY: EVALUATION OF ALTERNATIVE CHEMICAL STRIPPERS

    Science.gov (United States)

    The report gives results of an evaluation of the feasibility of using alternatives to high volatile organic compound/hazardous air pollutant (VOC/HAP) solvent-based, chemical strippers that are currently used in the furniture repair and refinishing industry to remove both traditi...

  12. Sedimentation behaviour and colloidal properties of porous, chemically modified silicas in non-aqueous solvents

    NARCIS (Netherlands)

    Vissers, J.P.C.; Laven, J.; Claessens, H.A.; Cramers, C.A.M.G.; Agterof, W.G.M.

    1997-01-01

    The sedimentation behaviour and colloidal properties of porous, chemically modified silicas dispersed in non-aqueous solvents have been studied. The free settling behaviour of non-aggregated silica suspensions could effectively be described with a modified Stokes equation that takes into account the

  13. Effects of organic solvents on hyaluronic acid nanoparticles obtained by precipitation and chemical crosslinking.

    Science.gov (United States)

    Bicudo, Rafaela Costa Souza; Santana, Maria Helena Andrade

    2012-03-01

    Hyaluronic acid is a hydrophilic mucopolysaccharide composed of alternating units of D-glucuronic acid and N-acetylglucosamine. It is used in many medical, pharmaceutical, and cosmetic applications, as sponges, films, or particle formulations. Hyaluronic acid nanoparticles can be synthesized free of oil and surfactants by nanoprecipitation in organic solvents, followed by chemical crosslinking. The organic solvent plays an important role in particles size and structure. Therefore, this study aimed to investigate the influence of acetone, ethanol, and isopropyl alcohol on the synthesis and physico-chemical properties of hyaluronic acid nanoparticles. Particles were crosslinked with adipic hydrazide and chloride carbodiimide under controlled conditions. The nanoparticles obtained with all three studied solvents were moderately electrostatically stable. Experiments with acetone produced the smallest particle size (120.44 nm) and polydispersity (0.27). The size and polydispersity of hyaluronic acid nanoparticles correlated with the surface tension between water and the organic solvents, not with the thermodynamic affinity of water for the organic solvents.

  14. PWR steam generator chemical cleaning. Phase I: solvent and process development. Volume II

    International Nuclear Information System (INIS)

    Larrick, A.P.; Paasch, R.A.; Hall, T.M.; Schneidmiller, D.

    1979-01-01

    A program to demonstrate chemical cleaning methods for removing magnetite corrosion products from the annuli between steam generator tubes and the tube support plates in vertical U-tube steam generators is described. These corrosion products have caused steam generator tube ''denting'' and in some cases have caused tube failures and support plate cracking in several PWR generating plants. Laboratory studies were performed to develop a chemical cleaning solvent and application process for demonstration cleaning of the Indian Point Unit 2 steam generators. The chemical cleaning solvent and application process were successfully pilot-tested by cleaning the secondary side of one of the Indian Point Unit 1 steam generators. Although the Indian Point Unit 1 steam generators do not have a tube denting problem, the pilot test provided for testing of the solvent and process using much of the same equipment and facilities that would be used for the Indian Point Unit 2 demonstration cleaning. The chemical solvent selected for the pilot test was an inhibited 3% citric acid-3% ascorbic acid solution. The application process, injection into the steam generator through the boiler blowdown system and agitation by nitrogen sparging, was tested in a nuclear environment and with corrosion products formed during years of steam generator operation at power. The test demonstrated that the magnetite corrosion products in simulated tube-to-tube support plate annuli can be removed by chemical cleaning; that corrosion resulting from the cleaning is not excessive; and that steam generator cleaning can be accomplished with acceptable levels of radiation exposure to personnel

  15. Chiral phase transition at finite chemical potential in 2 +1 -flavor soft-wall anti-de Sitter space QCD

    Science.gov (United States)

    Bartz, Sean P.; Jacobson, Theodore

    2018-04-01

    The phase transition from hadronic matter to chirally symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential (μ ), becoming first order at some finite value of μ , indicating the presence of a critical point. Using a three-flavor soft-wall model of anti-de Sitter/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.

  16. Supported liquid membrane stability in chiral resolution by chemically and physically modified membranes

    Energy Technology Data Exchange (ETDEWEB)

    Molinari, R.; Argurio, P. [Arcavata di Rende Univ. of Calabria, Arcavata di Rende, CS (Italy). Dept. of Chemical and Materials Engineering

    2001-04-01

    In the present work some stability studies on Supported Liquid Membranes (SLMs) to be used for chiral separations were realized. In particular, primary aim was to determine how a modification of the support surface influences the SLM stability. First, the procedure for support modification was optimised, making a screening of various compounds (sulphuric acid, nitric acid, chromic acid, sodium dodecyl sulphate (SDS), glycerol, oleic alcohol, propylene glycol (PPG), bovine serum albumin (BSA)) and testing their performance by means of contact angle measurements. Next, a second screening was realized by permeation tests in a stirred cell. Finally, to compare the stability of modified with unmodified support in a process of interest for chemical and/or biochemical industries, some permeation tests for resolution of DNB-DL-Leucine were realized in a re-circulation system. Results showed a better surface hydrophilization of chemically modified support and better stability of the sulphonated support. However, in operating conditions a little high stability of the unmodified support was obtained. [Italian] Nel presente lavoro sono stati realizzati degli studi di stabilita' di Membrane Liquide Supportate (SLMs) da impiegare in separazioni chirali. In particolare, obiettivo principale e' stato quello di determinare l'influenza che una modifica della superficie del supporto ha sulla stabilita' della SLM. Cosi', in un primo momento, e' stata ottimizzata le procedura di modifica del supporto, facendo una selezione tra vari composti (acido solforico, acido nitrico, acido cromico, sodio dodecil solfato (SDS), glicerolo, alcool oleico, glicole propilenico (PPG), siero di albumina bovina (BSA)) basata su misure dell'angolo di contatto. Successivamente, e' stata realizzata una seconda selezione mediante prove di permeazione in una cella agitata. Infine, con lo scopo di confrontare la stabilita' della SLM con supporto modificato rispetto

  17. 1H NMR spectra part 31: 1H chemical shifts of amides in DMSO solvent.

    Science.gov (United States)

    Abraham, Raymond J; Griffiths, Lee; Perez, Manuel

    2014-07-01

    The (1)H chemical shifts of 48 amides in DMSO solvent are assigned and presented. The solvent shifts Δδ (DMSO-CDCl3 ) are large (1-2 ppm) for the NH protons but smaller and negative (-0.1 to -0.2 ppm) for close range protons. A selection of the observed solvent shifts is compared with calculated shifts from the present model and from GIAO calculations. Those for the NH protons agree with both calculations, but other solvent shifts such as Δδ(CHO) are not well reproduced by the GIAO calculations. The (1)H chemical shifts of the amides in DMSO were analysed using a functional approach for near ( ≤ 3 bonds removed) protons and the electric field, magnetic anisotropy and steric effect of the amide group for more distant protons. The chemical shifts of the NH protons of acetanilide and benzamide vary linearly with the π density on the αN and βC atoms, respectively. The C=O anisotropy and steric effect are in general little changed from the values in CDCl3. The effects of substituents F, Cl, Me on the NH proton shifts are reproduced. The electric field coefficient for the protons in DMSO is 90% of that in CDCl3. There is no steric effect of the C=O oxygen on the NH proton in an NH…O=C hydrogen bond. The observed deshielding is due to the electric field effect. The calculated chemical shifts agree well with the observed shifts (RMS error of 0.106 ppm for the data set of 257 entries). Copyright © 2014 John Wiley & Sons, Ltd.

  18. ZnO nanostructure fabrication in different solvents transforms physio-chemical, biological and photodegradable properties

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Attarad; Ambreen, Sidra; Javed, Rabia; Tabassum, Saira [Department of Biotechnology, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ul Haq, Ihsan [Department of Pharmacy, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Zia, Muhammad, E-mail: ziachaudhary@gmail.com [Department of Biotechnology, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2017-05-01

    Zinc oxide (ZnO) nanostructures are synthesized in various organic solvents (acetone, chloroform, ethyl acetate, ethanol and methanol) and water via coprecipitation process using zinc acetate as precursor. The resultant ZnO nanoparticles, nano rods and nano sheets are characterized by UV–vis spectrophotometric analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). The variable size and geometry of nanoparticles depend upon medium used for synthesis. The synthesized ZnO nanostructures exhibit minor to moderate antioxidative (DPPH based free radical scavenging activity, total antioxidative potential and total reducing power) response. Mild to moderate antibacterial and antifungal activities, excellent antileishmanial potential (IC50 up to 3.76), and good cytotoxic perspective (LD50 up to 49.4) is also observed by the synthesized ZnO NPs. The nanoparticles also exhibit moderate α-amylase inhibition response. Furthermore the nanostructures are evaluated for methylene blue photodegradation response within 60 min time period. It is found that organic solvent alters shape, size and other physio-chemical properties of ZnO that ultimately modulate the biological, chemical, and environmental properties. - Highlights: • Zinc oxide nanoparticles are fabricated in different solvents using co-precipitation method • SEM, XRD and FTIR analysis confirms variation in physical and chemical characteristics of synthesized ZnO NPs • The synthesized ZnO demonstrates variation in biological, phytochemical and photodegradable properties.

  19. ZnO nanostructure fabrication in different solvents transforms physio-chemical, biological and photodegradable properties

    International Nuclear Information System (INIS)

    Ali, Attarad; Ambreen, Sidra; Javed, Rabia; Tabassum, Saira; Ul Haq, Ihsan; Zia, Muhammad

    2017-01-01

    Zinc oxide (ZnO) nanostructures are synthesized in various organic solvents (acetone, chloroform, ethyl acetate, ethanol and methanol) and water via coprecipitation process using zinc acetate as precursor. The resultant ZnO nanoparticles, nano rods and nano sheets are characterized by UV–vis spectrophotometric analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). The variable size and geometry of nanoparticles depend upon medium used for synthesis. The synthesized ZnO nanostructures exhibit minor to moderate antioxidative (DPPH based free radical scavenging activity, total antioxidative potential and total reducing power) response. Mild to moderate antibacterial and antifungal activities, excellent antileishmanial potential (IC50 up to 3.76), and good cytotoxic perspective (LD50 up to 49.4) is also observed by the synthesized ZnO NPs. The nanoparticles also exhibit moderate α-amylase inhibition response. Furthermore the nanostructures are evaluated for methylene blue photodegradation response within 60 min time period. It is found that organic solvent alters shape, size and other physio-chemical properties of ZnO that ultimately modulate the biological, chemical, and environmental properties. - Highlights: • Zinc oxide nanoparticles are fabricated in different solvents using co-precipitation method • SEM, XRD and FTIR analysis confirms variation in physical and chemical characteristics of synthesized ZnO NPs • The synthesized ZnO demonstrates variation in biological, phytochemical and photodegradable properties.

  20. Determination of solvents permeating through chemical protective clothing with a microsensor array.

    Science.gov (United States)

    Park, J; Zellers, E T

    2000-08-01

    The performance of a novel prototype instrument in determining solvents and solvent mixtures permeating through samples of chemical protective clothing (CPC) materials was evaluated. The instrument contains a mini-preconcentrator and an array of three polymer-coated surface-acoustic-wave (SAW) microsensors whose collective response patterns are used to discriminate among multiple permeants. Permeation tests were performed with a 2.54 cm diameter test cell in an open-loop configuration on samples of common glove materials challenged with four individual solvents, three binary mixtures, and two ternary mixtures. Breakthrough times, defined as the times required for the permeation rate to reach a value of 1 microg cm(-2) min(-1), determined by the instrument were within 3 min of those determined in parallel by manual sampling and gas chromatographic analysis. Permeating solvents were recognized (identified) from their response patterns in 59 out of 64 measurements (92%) and their vapor concentrations were quantified to an accuracy of +/- 31% (typically +/- 10%). These results demonstrate the potential for such instrumentation to provide semi-automated field or bench-top screening of CPC permeation resistance.

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

    Science.gov (United States)

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

    2014-10-10

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

  2. Random Forest Approach to QSPR Study of Fluorescence Properties Combining Quantum Chemical Descriptors and Solvent Conditions.

    Science.gov (United States)

    Chen, Chia-Hsiu; Tanaka, Kenichi; Funatsu, Kimito

    2018-04-22

    The Quantitative Structure - Property Relationship (QSPR) approach was performed to study the fluorescence absorption wavelengths and emission wavelengths of 413 fluorescent dyes in different solvent conditions. The dyes included the chromophore derivatives of cyanine, xanthene, coumarin, pyrene, naphthalene, anthracene and etc., with the wavelength ranging from 250 nm to 800 nm. An ensemble method, random forest (RF), was employed to construct nonlinear prediction models compared with the results of linear partial least squares and nonlinear support vector machine regression models. Quantum chemical descriptors derived from density functional theory method and solvent information were also used by constructing models. The best prediction results were obtained from RF model, with the squared correlation coefficients [Formula: see text] of 0.940 and 0.905 for λ abs and λ em , respectively. The descriptors used in the models were discussed in detail in this report by comparing the feature importance of RF.

  3. Solvent extraction as a method of promoting uranium enrichment by chemical exchange

    International Nuclear Information System (INIS)

    Fathurrachman.

    1995-01-01

    This thesis examines a chemical exchange process for uranium enrichment using solvent extraction. The system selected is the isotope exchange for uranium species in the form of uranous and uranyl chloride complexes. Solvent extraction has been studied before by French workers for this application but little was published on this. Much of this present work is therefore novel. The equilibrium data for the extraction of U(IV) as U 4+ and U(VI) as UO 2 2+ from hydrochloric media into an organic phase containing tri-n-octylamine (TOA) in benzene is given. Benzene is used to prevent third phase formation. In 4 M HCl U(VI) was found to be very soluble in the organic phase but U(IV) was virtually insoluble. Most of the equilibrium data has been correlated by the Langmuir isotherm. This thesis also outlines the methodology that has to be used to design a plant based on this process. (author)

  4. Molecular-level Design of Heterogeneous Chiral Catalysts

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-28

    ) 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.

  5. Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

    Science.gov (United States)

    Brkić, Dominik R.; Božić, Aleksandra R.; Marinković, Aleksandar D.; Milčić, Miloš K.; Prlainović, Nevena Ž.; Assaleh, Fathi H.; Cvijetić, Ilija N.; Nikolić, Jasmina B.; Drmanić, Saša Ž.

    2018-05-01

    The ratios of E/Z isomers of sixteen synthesized 1,3-dihydro-3-(substituted phenylimino)-2H-indol-2-one were studied using experimental and theoretical methodology. Linear solvation energy relationships (LSER) rationalized solvent influence of the solvent-solute interactions on the UV-Vis absorption maxima shifts (νmax) of both geometrical isomers using the Kamlet-Taft equation. Linear free energy relationships (LFER) in the form of single substituent parameter equation (SSP) was used to analyze substituent effect on pKa, NMR chemical shifts and νmax values. Electron charge density was obtained by the use of Quantum Theory of Atoms in Molecules, i.e. Bader's analysis. The substituent and solvent effect on intramolecular charge transfer (ICT) were interpreted with the aid of time-dependent density functional (TD-DFT) method. Additionally, the results of TD-DFT calculations quantified the efficiency of ICT from the calculated charge-transfer distance (DCT) and amount of transferred charge (QCT). The antimicrobial activity was evaluated using broth microdilution method. 3D QSAR modeling was used to demonstrate the influence of substituents effect as well as molecule geometry on antimicrobial activity.

  6. Solvent-extraction methods applied to the chemical analysis of uranium. III. Study of the extraction with inert solvents

    International Nuclear Information System (INIS)

    Vera Palomino, J.; Palomares Delgado, F.; Petrement Eguiluz, J. C.

    1964-01-01

    The extraction of uranium on the trace level is studied by using tributylphosphate as active agent under conditions aiming the attainment of quantitative extraction by means of a single step process using a number of salting-out agents and keeping inside the general lines as reported in two precedent papers. Two inert solvents were investigated, benzene and cyclohexane, which allowed to derive the corresponding empirical equations describing the extraction process and the results obtained were compared with those previously reported for solvents which, like ethyl acetate and methylisobuthylketone, favour to a more or less extend the extraction of uranium. (Author) 4 refs

  7. Silver Films with Hierarchical Chirality.

    Science.gov (United States)

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

    2017-07-17

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

  8. Relation between separation factor of carbon isotope and chemical reaction of CO2 with amine in nonaqueous solvent

    International Nuclear Information System (INIS)

    Takeshita, Kenji; Kitamoto, Asashi

    1989-01-01

    The separation factor for carbon isotope exchange reaction between CO 2 and amine in nonaqueous solvent was related to absorption reaction of CO 2 in a solution. The test solutions were mixtures of primary amine (such as butylamine and tert-butylamine) or secondary amine (such as diethylamine, dipropylamine and dibutylamine) diluted with nonpolar solvent (octane or triethyalmine) or polar solvent (methanol), respectively. The isotope exchange reaction consists of three steps related to chemical reaction of CO 2 in amine and nonaqueous solvent mixture, namely the reaction between CO 2 and carbamic acid, that between CO 2 and amine carbamate, and that between CO 2 and carbamic ion. Above all, the isotope separation factor between CO 2 and carbamic acid had the highest value. The overall separation factor can be higher in amine-nonaqueous solvent mixture where the concentration of carbamic acid becomes higher. (author)

  9. Chiral Responsive Liquid Quantum Dots.

    Science.gov (United States)

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

    2017-08-01

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

  10. Solvent Effects on Oxygen-17 Chemical Shifts in Amides. Quantitative Linear Solvation Shift Relationships

    Science.gov (United States)

    Díez, Ernesto; Fabián, Jesús San; Gerothanassis, Ioannis P.; Esteban, Angel L.; Abboud, José-Luis M.; Contreras, Ruben H.; de Kowalewski, Dora G.

    1997-01-01

    A multiple-linear-regression analysis (MLRA) has been carried out using the Kamlet-Abboud-Taft (KAT) solvatochromic parameters in order to elucidate and quantify the solvent effects on the17O chemical shifts ofN-methylformamide (NMF),N,N-dimethylformamide (DMF),N-methylacetamide (NMA), andN,N-dimethylacetamide (DMA). The chemical shifts of the four molecules show the same dependence (in ppm) on the solvent polarity-polarizability, i.e., -22π*. The influence of the solvent hydrogen-bond-donor (HBD) acidities is slightly larger for the acetamides NMA and DMA, i.e., -48α, than for the formamides NMF and DMF, i.e., -42α. The influence of the solvent hydrogen-bond-acceptor (HBA) basicities is negligible for the nonprotic molecules DMF and DMA but significant for the protic molecules NMF and NMA, i.e., -9β. The effect of substituting the N-H hydrogen by a methyl group amounts to -5.9 ppm in NMF and 5.4 ppm in NMA. The effect of substituting the O=C-H hydrogen amounts to 5.5 ppm in NMF and 16.8 ppm in DMF. The model of specific hydration sites of amides by I. P. Gerothanassis and C. Vakka [J. Org. Chem.59,2341 (1994)] is settled in a more quantitative basis and the model by M. I. Burgar, T. E. St. Amour, and D. Fiat [J. Phys. Chem.85,502 (1981)] is critically evaluated.17O hydration shifts have been calculated for formamide (FOR) by the ab initio LORG method at the 6-31G* level. For a formamide surrounded by the four in-plane molecules of water in the first hydration shell, the calculated17O shift change due to the four hydrogen bonds, -83.2 ppm, is smaller than the empirical hydration shift, -100 ppm. The17O shift change from each out-of-plane water molecule hydrogen-bonded to the amide oxygen is -18.0 ppm. These LORG results support the conclusion that no more than four water molecules are hydrogen-bonded to the amide oxygen in formamide.

  11. Effect of organic solvents on dissolution process of mechano-chemically activated molybdenum by inorganic acid solutions

    International Nuclear Information System (INIS)

    Shevtsova, I.Ya.; Chernyak, A.S.; Khal'zov, A.A.

    1992-01-01

    The process of chemical dissolution of mechanochemically activated and nonactivated molybdenite by inorganic acid solutions in certain organic solvents of different nature was considered. It is shown that the highest extraction of molybdenum in solution is achieved in the presence of nitric acid. The dissociation constant of the acid used in the given organic solvent does not affect molybdenite solubility. When dissolving molybdenite by solutions of nitric acid in carbonic acids, alcohols and esters, the solubility of the concentrate depends on the length of hydrocarbon chain of the organic solvent and dispersion degree of mineral source material

  12. Physico-chemical properties of Pd nanoparticles produced by Pulsed Laser Ablation in different organic solvents

    International Nuclear Information System (INIS)

    Cristoforetti, Gabriele; Pitzalis, Emanuela; Spiniello, Roberto; Ishak, Randa; Giammanco, Francesco; Muniz-Miranda, Maurizio; Caporali, Stefano

    2012-01-01

    Palladium nanoparticles are arousing an increasing interest because of their strong activity in heterogeneous catalysis in a wide range of reactions. Driven by the interest of producing Pd nanoparticles to be deposited for catalysis over hydrophobic supports, we investigated their synthesis via Pulsed Laser Ablation in Liquid in several organic solvents, as acetone, ethanol, 2-propanol, toluene, n-hexane. The colloids were produced by using a Nd:YAG ns laser and without the addition of surfactant agents. The morphology, composition, stability and oxidation state of the obtained nanoparticles were investigated by TEM-EDS analysis, UV-vis spectroscopy, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy. The results evidence that the nature of the solvent influences both the yield and the physico-chemical properties of the produced nanoparticles. While in acetone and alcohols spheroidal, non aggregated and stable particles are obtained, in case of toluene and n-hexane few unstable particles surrounded by a gel-like material are produced. Raman/XPS measurements suggest the presence of amorphous or graphitic carbon onto crystalline Pd nanoparticles, which could have hindered their growth and determined the observed smaller sizes if compared to nanoparticles produced in water. The stability of Pd colloids obtained in acetone and alcohols was attributed to adsorbed anions like enolates or alcoholates; non polar solvents like toluene and n-hexane, unable to give rise to adsorbed anionic species, cannot provide any stabilization to the palladium nanoparticles. XPS analyses also evidenced a partial oxidation of particles surface, with a ratio Pd 2+ :Pd 0 of 1:2.5 and 1:4 in acetone and ethanol, respectively.

  13. Chemical chiral pollution: Impact on the society and science and need of the regulations in the 21st century.

    Science.gov (United States)

    Basheer, Al Arsh

    2018-04-01

    The chiral pollution is a serious issue for our health and environment due to the enantio-selective biodegradation of the chiral pollutants. It has adverse impact on our society and science. There is a big loss of our economy due to the use of racemic agrochemicals. The most notorious chiral pollutants are pesticides, polychloro biphenyls, polyaromatic hydrocarbons, brominated flame retardants, drugs, and pharmaceuticals. More than 1500 chiral pollutants are present in the environment. Unfortunately, there is no regulation and control of the chiral pollutants. Therefore, it is an urgent need of the present 21st century to develop a data bank on the chiral pollutants, guidelines for controlling the production, sale and use of the racemic agrochemicals and the other industrial products. The Governments of the different countries should come forward to initiate the regulations. US, FDA, US EPA, and WHO are the most important regulatory authorities and should think about the chiral pollutants. The present article highlights the impact of the chiral pollution on the society and science. Besides, the efforts have also been made to emphasize the need of the regulations to control the chiral pollution. © 2017 Wiley Periodicals, Inc.

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

    Science.gov (United States)

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

    2018-05-16

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

  15. Van't Hoff's law for active suspensions: the role of the solvent chemical potential

    NARCIS (Netherlands)

    Rodenburg, Jeroen; Dijkstra, Marjolein; van Roij, Rene

    2017-01-01

    We extend Van’t Hoff's law for the osmotic pressure to a suspension of active Brownian particles. The propelled particles exert a net reaction force on the solvent, and thereby either drive a measurable solvent flow from the connecting solvent reservoir through the semipermeable membrane, or

  16. Thermodynamic method for obtaining the solubilities of complex medium-sized chemicals in pure and mixed solvents

    DEFF Research Database (Denmark)

    Abildskov, Jens; O'Connell, J.P.

    2005-01-01

    This paper extends our previous simplified approach to using group contribution methods and limited data to determine differences in solubility of sparingly soluble complex chemicals as the solvent is changed. New applications include estimating temperature dependence and the effect of adding cos....... Though we present no new solution theory, the paper shows an especially efficient use of thermodynamic models for solvent and cosolvent selection for product formulations. Examples and discussion of applications are given. (c) 2004 Elsevier B.V. All rights reserved.......This paper extends our previous simplified approach to using group contribution methods and limited data to determine differences in solubility of sparingly soluble complex chemicals as the solvent is changed. New applications include estimating temperature dependence and the effect of adding...

  17. Effect of protic solvents on CdS thin films prepared by chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Pin-Chuan, E-mail: pcyao@mail.dyu.edu.tw; Chen, Chun-Yu

    2015-03-31

    In this study, cadmium sulfide (CdS) thin films are grown on glass substrates by chemical bath deposition (CBD) in an aqueous bath containing 10–20 vol.% alcohol. The roles of ethanol as a protic solvent that substantially improves the quality of films are explored extensively. The deposited films in an alcohol bath are found to be more compact and smoother with smaller CdS grains. The X-ray diffractograms of the samples confirm that all films were polycrystalline with mixed wurtzite (hexagonal) and zinkblende (cubic) phases. Raman spectra indicate that, for a film deposited in an alcohol bath, the position of 1LO is closer to the value for single crystal CdS, indicating that these films have a high degree of crystallinity. The as-deposited CdS thin films in a 10 vol.% alcohol bath were found to have the highest visible transmittance of 81.9%. XPS analysis reveals a stronger signal of C1s for samples deposited in the alcohol baths, indicating that there are more carbonaceous residues on the films with protic solvent than on the films with water. A higher XPS S/Cd atomic ratio for films deposited in an alcohol bath indicates that undesirable surface reactions (leading to sulfur containing compounds other than CdS) occur less frequently over the substrates. - Highlights: • Study of CBD-CdS films grown in an alcohol-containing aqueous bath is reported. • The deposited films in an alcohol bath are more compact with smaller CdS grains. • Raman spectra show that in an alcohol bath, the CdS film has a better crystallinity. • XPS reveals more carbon residues remain on the films deposited using alcohol bath. • In an alcohol bath, the undesirable surface reactions with Cd ions were hindered.

  18. COMPARISON OF SORPTION ENERGTICS FOR HYDROPHOBIC ORGANIC CHEMICALS BY SYNTHETIC AND NATURAL SORBENTS FROM METHANOL/WATER SOLVENT MIXTURES

    Science.gov (United States)

    Reversed-phase liquid chromatography (RPLC) was used to investigate the thermodynamics and mechanisms of hydrophobic organic chemical (HOC) retention from methanol/water solvent mixtures. The enthalpy-entropy compensation model was used to infer that the hydro- phobic sorptive me...

  19. Radiological pathways analysis for spent solvents from the boiler chemical cleaning at the Pickering Nuclear Site

    International Nuclear Information System (INIS)

    Garisto, N.C.; Eslami, Z.; Hodgins, S.; Beaman, T.; Von Svoboda, S.; Marczak, J.

    2006-01-01

    Spent solvents are generated as a result of Boiler Chemical Cleanings (BCC) at CANDU reactor sites. These solutions contain small amount of radioactivity from a number of different sources including: Cut tubes - short sections of boiler tubes are infrequently removed from the boilers for a detailed characterization. These tubes are typically only plugged at the tubesheet allowing the primary side deposits to be exposed to BCC solvents. Tube leaks - primary to secondary side leaks also occur infrequently as a result of tube degradation. Radioactivity from the leaking fluid can consequently be deposited in the sludge on the secondary side of the tubes. Diffusion of tritium - during normal operation of the reactor units, tritium slowly diffuses from the heavy water in the primary heat-transfer system to the light-water coolant on the secondary side. Some of this tritium is retained in the secondary side deposits. The Pickering Nuclear Generating Station (PNGS) would like the flexibility to have several options for handling the spent solvent waste and associated rinse water from BCC. To this end, a radiological pathways analysis was undertaken to determine dose consequences associated with each option. Sample results from this study are included in this paper. The pathways analysis is used in this study to calculate dose to hypothetical receptors including individuals such as truck drivers, incinerator workers, residue (ash) handlers, residents who live near the landfill, inadvertent intruders into the landfill after closure and residents who live near the outfall. This dose is compared to a de minimis dose. A de minimis dose or dose rate represents a level of risk, which is generally accepted as being of no significance. Shipments of spent solvents and rinse water with corresponding doses below de minimis can be sent to conventional (i.e., non-radioactive) landfills for incineration and disposal as the radioactive dose associated with them is much less than natural

  20. Nonlinear spectroscopic studies of chiral media

    International Nuclear Information System (INIS)

    Belkin, Mikhail Alexandrovich

    2004-01-01

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

  1. 1H NMR study of the solvent THF concerning their structural and dynamical properties in chemically Li-intercalated SWNT

    KAUST Repository

    Schmid, Marc R.

    2011-09-01

    Structural and dynamical properties of the THF solvent in single-walled carbon nanotubes intercalated with lithium are investigated by NMR. 1H NMR experiments reveal the existence of two types of inequivalent THF solvent molecules with different chemical environments and dynamical behavior. At low temperatures THF molecules perpendicularly arranged in between adjacent SWNT presumably exhibit a restricted rotation around their dipolar axis. At higher temperatures THF molecules are isotropically rotating and diffusing along the interstitial channels of the SWNT bundles. © 2011 Elsevier B.V. All rights reserved.

  2. 1H NMR study of the solvent THF concerning their structural and dynamical properties in chemically Li-intercalated SWNT

    KAUST Repository

    Schmid, Marc R.; Goze-Bac, Christophe; Bouhrara, Mohamed; Saih, Youssef; Mehring, Michael; Abou-Hamad, Edy

    2011-01-01

    Structural and dynamical properties of the THF solvent in single-walled carbon nanotubes intercalated with lithium are investigated by NMR. 1H NMR experiments reveal the existence of two types of inequivalent THF solvent molecules with different chemical environments and dynamical behavior. At low temperatures THF molecules perpendicularly arranged in between adjacent SWNT presumably exhibit a restricted rotation around their dipolar axis. At higher temperatures THF molecules are isotropically rotating and diffusing along the interstitial channels of the SWNT bundles. © 2011 Elsevier B.V. All rights reserved.

  3. Enrichment of 13C by chemical exchange between CO2 and amine carbamate in nonaqueous solvent

    International Nuclear Information System (INIS)

    Raica, Paula; Axente, D.

    2009-01-01

    Full text: Enrichment of 13 C by chemical exchange between CO 2 and amine carbamate in nonaqueous solvent has been mathematically modelled in two ways. The height equivalent to a theoretical plate and steady-state separation, based on the two models, have been obtained. If only the isotopic exchange between CO 2 gas and amine carbamate is considered, the model can estimate the process performance for pressures close to the atmospheric one and room temperature. For process analysis at pressures higher than atmospheric one and lower temperatures, a two-step model has been developed. Using the two models the effects of pressure increasing have been studied. At atmospheric pressure and 2M DNBA - methanol solution the isotope transfer rate is lower at 5 deg. C than at 25 deg. C. The isotope transfer is supported by pressure increasing according the increase of the CO 2 concentration in the amine solution. A lower temperature determines also an increase in the concentration of dissolved CO 2 and, for this reason, at 5 deg.C and higher pressures the isotope exchange reaction rate is higher than at 25 deg. C, HETP being lower with more than 100% at 5 deg. C than at 25 deg. C. (authors)

  4. Effect of Organic Solvents in Preparation of Silica-Based Chemical Gel Decontaminates for Decontamination of Nuclear Facilities

    International Nuclear Information System (INIS)

    Yoon, Suk Bon; Jung, Chong Hun; Kim, Chang Ki; Choi, Byung Seon; Lee, Kune Woo; Moon, Jei Kwon

    2011-01-01

    Decontamination of nuclear facilities is necessary to reduce the radiation field during normal operations and decommissioning of complex equipment such as stainless steel components, other iron-based steel and alloys, metal surfaces, structural materials and so on. Chemical decontamination technology in particular is a highly effective method to remove the radioactive contamination through a chemical dissolution or a redox reaction. However, this method has the serious drawback due to the generation of large amounts of the radioactive liquid wastes. Recently, a few literatures have been reported for the preparation of the chemical gel decontaminants to reduce the amount of the radioactive liquid wastes and to enhance the decontamination efficiency through increasing the contact time between the gels and the radioactive contaminants. In the preparation of the chemical gels, the control of the viscosity highly depends on the amount of a coviscosifier used among the components of the chemical gels consisted of a viscosifier, a coviscosifier, and a chemical decontaminant. In this works, a new effective method for the preparation of the chemical gel was investigated by introducing the organic solvents. The mixture solution of the coviscosifier and organic solvent was more effective in the control of the viscosity compared with that of the coviscosifier only in gels. Furthermore, the decontamination efficiency of the chemical gels measured by using the multi-channel analyzer (MCA) showed the high decontamination factor for Co-60 and Cs-137 contaminated on the surface of the stainless steel 304

  5. Determination of Absolute Configuration in Chiral Solvents with Nuclear Magnetic Resonance. A Combined Molecular Dynamics/Quantum Chemical Study

    Czech Academy of Sciences Publication Activity Database

    Kessler, Jiří; Dračínský, Martin; Bouř, Petr

    2015-01-01

    Roč. 119, č. 21 (2015), s. 5260-5268 ISSN 1089-5639 R&D Projects: GA ČR GAP208/11/0105; GA ČR GA13-03978S; GA MŠk(CZ) LH11033 Grant - others:GA MŠk(CZ) LM2010005; GA MŠk(CZ) ED3.2.00/08.0144; GA AV ČR(CZ) M200551205 Institutional support: RVO:61388963 Keywords : X-ray crystallography * NMR spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.883, year: 2015

  6. Mathematical modelling of simultaneous solvent evaporation and chemical curing in thermoset coatings: A parameter study

    DEFF Research Database (Denmark)

    Kiil, Søren

    2011-01-01

    A mathematical model, describing the curing behaviour of a two-component, solvent-based, thermoset coating, is used to conduct a parameter study. The model includes curing reactions, solvent intra-film diffusion and evaporation, film gelation, vitrification, and crosslinking. A case study with a ...

  7. Laboratory Tests to Determine the Chemical and Physical Characteristics of Propellant-Solvent-Fuel Oil Mixtures

    Science.gov (United States)

    1990-02-01

    isocyanates and many heterocyclic alcohols and ketones such as furfural and camphor also possess some I solvent power for nitrocellulose. Amines...34Estimation of Solvent Power by the Dilution-Ratio Method," J. Appl. Chem. (London) 7, 332 (1957). U R.P. Teulings, "A Multivariable Study of the Adsorption of

  8. Enantioselective catalytic syntheses of alpha-branched chiral amines

    DEFF Research Database (Denmark)

    Brase, S.; Baumann, T.; Dahmen, S.

    2007-01-01

    Chiral amines play a pivotal role in fine chemical and natural product syntheses and the design of novel materials.......Chiral amines play a pivotal role in fine chemical and natural product syntheses and the design of novel materials....

  9. Holographic Chiral Magnetic Spiral

    International Nuclear Information System (INIS)

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

    2010-06-01

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

  10. Chirality in adsorption on solid surfaces.

    Science.gov (United States)

    Zaera, Francisco

    2017-12-07

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

  11. Nanoencapsulation of OPAA With Mesoporous Materials for Chemical Agent Decontamination in Organic Solvents

    National Research Council Canada - National Science Library

    Ong, K. K; Dong, H; Wei, Y; Cheng, T-c; Yin, R

    2003-01-01

    .... The enzyme activity in different matrices was evaluated in various organic solvents. Significant activities were retained in most of these matrices, particularly in the presence of acetone and dimethyl formamide...

  12. Chiral superconductors.

    Science.gov (United States)

    Kallin, Catherine; Berlinsky, John

    2016-05-01

    Chiral superconductivity is a striking quantum phenomenon in which an unconventional superconductor spontaneously develops an angular momentum and lowers its free energy by eliminating nodes in the gap. It is a topologically non-trivial state and, as such, exhibits distinctive topological modes at surfaces and defects. In this paper we discuss the current theory and experimental results on chiral superconductors, focusing on two of the best-studied systems, Sr2RuO4, which is thought to be a chiral triplet p-wave superconductor, and UPt3, which has two low-temperature superconducting phases (in zero magnetic field), the lower of which is believed to be chiral triplet f-wave. Other systems that may exhibit chiral superconductivity are also discussed. Key signatures of chiral superconductivity are surface currents and chiral Majorana modes, Majorana states in vortex cores, and the possibility of half-flux quantum vortices in the case of triplet pairing. Experimental evidence for chiral superconductivity from μSR, NMR, strain, polar Kerr effect and Josephson tunneling experiments are discussed.

  13. Electrochemical/chemical oxidation of bisphenol A in a four-electron/two-proton process in aprotic organic solvents

    International Nuclear Information System (INIS)

    Chan, Ya Yun; Yue, Yanni; Li, Yongxin; Webster, Richard D.

    2013-01-01

    Graphical abstract: - Highlights: • Bisphenol A undergoes a chemically irreversible voltammetric oxidation process. • Chemical oxidation was performed to overcome adsorption effects that cause electrode fouling. • A new product was isolated from chemical oxidation with 4 mol equiv. of the one-electron oxidant, NO + . • The oxidative mechanism was proposed to be a four-electron/two-proton process. - Abstract: The electrochemical behavior of bisphenol A (BPA) was examined using cyclic voltammetry, bulk electrolysis and chemical oxidation in aprotic organic solvents. It was found that BPA undergoes a chemically irreversible voltammetric oxidation process to form compounds that cannot be electrochemically converted back to the starting materials on the voltammetric timescale. To overcome the effects of electrode fouling during controlled potential electrolysis experiments, NO + was used as a one-electron chemical oxidant. A new product, hydroxylated bisdienone was isolated from the chemical oxidation of BPA with 4 mol equiv of NO + SbF 6 − in low water content CH 3 CN. The structure of the cation intermediate species was deduced and it was proposed that BPA is oxidized in a four-electron/two-proton process to form a relatively unstable dication which reacts quickly in the presence of water in acetonitrile (in a mechanism that is similar to phenols in general). However, as the water content of the solvent increased it was found that the chemical oxidation mechanism produced a nitration product in high yield. The findings from this study provide useful insights into the reactions that can occur during oxidative metabolism of BPA and highlight the possibility of the role of a bisdienone cation as a reactive metabolite in biological systems

  14. A study of the solvent effect on the chemical interaction between ortho-positronium and iron(III)-chloride

    International Nuclear Information System (INIS)

    Vertes, A.

    1980-01-01

    The chemical rate constant (k) between ortho-positronium (o-Ps) and iron(III)-chloride was measured in donor solvents as benzene, acetone, pyridine and ethanol. The minimal k was obtained in benzene and the maximal one in acetone. The minimal k value was explained by the low dispersity of FeCl 3 in benzene, and the high rate of the interaction in acetone was considered to be the result of the presence of monomer and dimer iron(III)-species and of the chloride coordination to iron(III). The probability of Ps formation depended only on the character of the solvent and not on the concentration of the FeCl 3 solute. (author)

  15. Description of the equilibrium conditions of chemical reactions in various solvents

    International Nuclear Information System (INIS)

    Roehl, H.

    1983-01-01

    Empirical knowledge is taken as the basis for establishing a method to predict the equilibrium conditions of reactions of macrocyclic polyethers and monovalent metal cations in various solvents. The reactions in the solvents under review can be well described by the donor number DN according to Gutmann, and by the parameters alpha and pi-asterisk for the H bonding donor and polarity/polarisability, respectively, using a three-parameter equation according to Kamlet/Taft. This applies to both protic and aprotic solvents. The calculations rely on data found in the literature and on own experimental results obtained by microcalorimetric examinations. The evaluation methods evolved for this purpose also allow, by means of additional dilution experiments, to convert the ''integral'', microcalorimetrically obtained complex stability constants, (i.e. those non-discriminating between different types of state such as ions or ion pairs) to the corresponding ''differentiating'' constants (referring to purely ionic quantities), and this applied to the various solvents used. The method does not use foreign ions and can thus also be applied to those cases for which the normal standardisation of reaction conditions published in the literature cannot be maintained (e.g. for reasons of solubility). In some cases it was possible to obtain additional information on the dissociation behaviour of the salts used, which revealed differently strong inclination to form higher aggregations in solution, as shown e.g. by the strong concentration dependence of the salt ion pair dissociation constants obtained. (orig./EF) [de

  16. Molecular dynamics studies and quantification of the effect of chirality on the formation of liquid crystal mesophases

    International Nuclear Information System (INIS)

    Solymosi, Miklos

    2002-01-01

    Results are presented from theoretical studies and from a series of molecular dynamics simulations undertaken to quantify the effect of chirality on the formation of liquid crystal mesophases. In the theoretical studies we have proposed a scaled chiral index with a formulation which allows comparison to be made between molecules comprising different numbers of atoms. We have undertaken chirality calculations utilizing the proposed scaled chiral index, G 0S , for one optimized static molecular geometry for a range of liquid crystal chiral dopants and ferroelectric liquid crystal molecules. The scaled chiral index, G 0S , allows a rapid calculation to be made of a pseudoscalar quantity which shows a good correlation with the helical twisting power of liquid crystal chiral dopants in a nematic liquid crystal solvent. This could prove a powerful aid in the design of novel dopant molecules where the dopant is rigid and the helical twisting is predominantly a steric effect. The same scaled chirality index, G 0S , calculation for ferroelectric liquid crystal molecules hints at an inverse correlation with spontaneous polarization agreeing with some experimental results. The scaled chiral index is a chemically useful index that can also be decomposed into atomic or functional group contributions, thereby creating a new measure of the asymmetric potential of functional groups and their different possible substitution positions. In the molecular dynamics simulation studies we have investigated two three-site Gay-Berne models, one chiral and the other achiral, each with a rotated central site forming a zigzag shape. In the chiral model one of the end site was additionally rotated out of the plane of the other two sites by a chiral angle θ c . Results from the achiral phase simulations support the theory that steric molecular shape can be associated with a driving force that leads to the smectic A - smectic C phase transition since such a transition was observed in the achiral

  17. 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.

  18. Solvent extraction of some metal ions by dithiocarbamate types of chemically modified lipophilic chitosan

    International Nuclear Information System (INIS)

    Inoue, K.; Nakagawa, H.; Naganawa, H.; Tachimori, S.

    2001-01-01

    Chitosan is a basic polysaccharide containing primary amino groups with high reactivity. we prepared O,O'-decanoyl chitosan and dithiocarbamate O,O'-decanoyl chitosan; the former was soluble in chloroform and toluene, while latter was soluble not only these diluents but also in some aliphatic diluents such as hexane and kerosene which are employed in commercial scale solvent extraction. Solvent extraction by dithiocarbamate O,O'-decanoyl chitosan in kerosene was tested for some base metal ions from sulfuric acid solution. The sequence of selectivity for these metal ions was found to be as follows: Cu(II) >> Ni(II) > Cd(II) ∼ Fe(III) > Co(II) ∼ Zn(II). Copper(II) was quantitatively extracted at pH > 1 and quantitatively stripped with 2 M sulfuric acid solution. Solvent extraction of silver(I) and gold(III) from hydrochloric acid as well as lanthanides and americium(III) from nitrate solution were also tested. Americium was selectively extracted over trivalent lanthanides, suggesting a high possibility for the final treatment of high level radioactive wastes. (authors)

  19. THE CHEMICAL AND RADIATION RESISTANCE OF POLYPHENYLENE SULFIIDE AS ENCOUNTERED IN THE MODULAR CAUSTIC SIDE SOLVENT EXTRACTION PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F.; Herman, D.; Poirier, M.; Fink, S.

    2011-06-30

    Polyphenylene sulfide (PPS) is a semicrystalline polymer with excellent engineering plastic properties and suitable processing temperatures. PPS can also be made containing branches (using a trifunctional monomer) and with crosslinked microstructure (when curing the monomer at high temperature in the presence of oxygen). PPS is made from the condensation reaction between para-dichlorobenzene and sodium sulfide with the assistance of a catalyst (to lower the activation barrier). The synthesis conditions for making PPS has evolved since its invention in the 1960's to the optimal conditions developed by the Philips Corporation in the 1970's. The resulting polymer consists of chemically stable molecular moieties such as benzene rings and ether like sulfur linkages between the aromatic rings. Polyphenylene sulfide (PPS) is extremely resistant to gamma irradiation, caustic solution, and dilute nitric acid. PPS is the material of construction for the coalescers used in the Modular Caustic-Side Solvent Extraction Unit (MCU). After applying the equivalent of 3.3 E8 rad (330 Mrad), or the equivalent of 11 years of gamma irradiation (assuming a stripping solution concentration of 7.5 Ci/gal), and several months of exposures to 3M caustic solution and caustic salt simulant, no dimensional changes nor chemical changes were detected in PPS whether the PPS was in fiber form or in a composite with E-glass fibers. However, PPS acts as a media for heterogeneous nucleation. In particular, PPS appears to favor aluminosilicate formation in saturated solutions of aluminum and silicon in caustic environments. Parallel testing, in progress, is examining the stability of PPS when exposed to the new solvent formulation under development for MCU. Preliminary data, after two months of exposure, demonstrates PPS is stable to the new solvent.

  20. Advanced hybrid process with solvent extraction and pyro-chemical process of spent fuel reprocessing for LWR to FBR

    International Nuclear Information System (INIS)

    Fujita, Reiko; Mizuguchi, Koji; Fuse, Kouki; Saso, Michitaka; Utsunomiya, Kazuhiro; Arie, Kazuo

    2008-01-01

    Toshiba has been proposing a new fuel cycle concept of a transition from LWR to FBR. The new fuel cycle concept has better economical process of the LWR spent fuel reprocessing than the present Purex Process and the proliferation resistance for FBR cycle of plutonium with minor actinides after 2040. Toshiba has been developing a new Advanced Hybrid Process with Solvent Extraction and Pyrochemical process of spent fuel reprocessing for LWR to FBR. The Advanced Hybrid Process combines the solvent extraction process of the LWR spent fuel in nitric acid with the recovery of high pure uranium for LWR fuel and the pyro-chemical process in molten salts of impure plutonium recovery with minor actinides for metallic FBR fuel, which is the FBR spent fuel recycle system after FBR age based on the electrorefining process in molten salts since 1988. The new Advanced Hybrid Process enables the decrease of the high-level waste and the secondary waste from the spent fuel reprocessing plants. The R and D costs in the new Advanced Hybrid Process might be reduced because of the mutual Pyro-chemical process in molten salts. This paper describes the new fuel cycle concept of a transition from LWR to FBR and the feasibility of the new Advanced Hybrid Process by fundamental experiments. (author)

  1. Enantioselective solvent-free Robinson annulation reactions

    Indian Academy of Sciences (India)

    Unknown

    solvents to effect an asymmetric synthesis is an important step forward towards ... In continuation of our preliminary communication 2, we wish to ..... formation of chiral enamine 74 from the reaction of S-proline with pro-R carbonyl group.

  2. Microbial dynamics during and after in situ chemical oxidation of chlorinated solvents

    NARCIS (Netherlands)

    Sutton, N.B.; Atashgahi, S.; Wal, van der J.; Wijn, G.; Grotenhuis, J.T.C.; Smidt, H.; Rijnaarts, H.

    2015-01-01

    In situ chemical oxidation (ISCO) followed by a bioremediation step is increasingly being considered as an effective biphasic technology. Information on the impact of chemical oxidants on organohalide respiring bacteria (OHRB), however, is largely lacking. Therefore, we used quantitative PCR (qPCR)

  3. Chemical composition separation of a propylene-ethylene random copolymer by high temperature solvent gradient interaction chromatography.

    Science.gov (United States)

    Liu, Yonggang; Phiri, Mohau Justice; Ndiripo, Anthony; Pasch, Harald

    2017-11-03

    A propylene-ethylene random copolymer was fractionated by preparative temperature rising elution fractionation (TREF). The structural heterogeneity of the bulk sample and its TREF fractions was studied by high temperature liquid chromatography with a solvent gradient elution from 1-decanol to 1,2,4-trichlorobenzene. HPLC alone cannot resolve those propylene-ethylene copolymers with high ethylene content in the bulk sample, due to their low weight fractions in the bulk sample and a small response factor of these components in the ELSD detector, as well as their broad chemical composition distribution. These components can only be detected after being separated and enriched by TREF followed by HPLC analysis. Chemical composition separations were achieved for TREF fractions with average ethylene contents between 2.1 and 22.0mol%, showing that copolymers with higher ethylene contents were adsorbed stronger in the Hypercarb column and eluted later. All TREF fractions, except the 40°C fraction, were relatively homogeneous in both molar mass and chemical composition. The 40°C fraction was rather broad in both molar mass and chemical composition distributions. 2D HPLC showed that the molar masses of the components containing more ethylene units were getting lower for the 40°C fraction. HPLC revealed and confirmed that co-crystallization influences the separation in TREF of the studied propylene-ethylene copolymer. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Room temperature molten salts: neoteric "green" solvents for chemical reactions and processes

    OpenAIRE

    Dupont, Jaírton; Consorti, Crestina S.; Spencer, John

    2000-01-01

    Líquidos iônicos, em particular aqueles derivados do cátion 1,3-dialquilimidazólio, que possuem uma ampla faixa de temperatura em suas fases líquidas, pressões de vapores muito pequenas, baixas viscosidades e elevada estabilidade térmica e química vêm emergindo como uma nova classe de solventes “verdes” para processos de extração e separação, síntese orgânica e catálise. Os principais resultados obtidos com estes líquidos em Química Limpa nos últimos dois anos são objeto deste artigo de revis...

  5. Directed Self-Assembly of Triblock Copolymer on Chemical Patterns for Sub-10-nm Nanofabrication via Solvent Annealing.

    Science.gov (United States)

    Xiong, Shisheng; Wan, Lei; Ishida, Yoshihito; Chapuis, Yves-Andre; Craig, Gordon S W; Ruiz, Ricardo; Nealey, Paul F

    2016-08-23

    Directed self-assembly (DSA) of block copolymers (BCPs) is a leading strategy to pattern at sublithographic resolution in the technology roadmap for semiconductors and is the only known solution to fabricate nanoimprint templates for the production of bit pattern media. While great progress has been made to implement block copolymer lithography with features in the range of 10-20 nm, patterning solutions below 10 nm are still not mature. Many BCP systems self-assemble at this length scale, but challenges remain in simultaneously tuning the interfacial energy atop the film to control the orientation of BCP domains, designing materials, templates, and processes for ultra-high-density DSA, and establishing a robust pattern transfer strategy. Among the various solutions to achieve domains that are perpendicular to the substrate, solvent annealing is advantageous because it is a versatile method that can be applied to a diversity of materials. Here we report a DSA process based on chemical contrast templates and solvent annealing to fabricate 8 nm features on a 16 nm pitch. To make this possible, a number of innovations were brought in concert with a common platform: (1) assembling the BCP in the phase-separated, solvated state, (2) identifying a larger process window for solvated triblock vs diblock BCPs as a function of solvent volume fraction, (3) employing templates for sub-10-nm BCP systems accessible by lithography, and (4) integrating a robust pattern transfer strategy by vapor infiltration of organometallic precursors for selective metal oxide synthesis to prepare an inorganic hard mask.

  6. Chirality invariance and 'chiral' fields

    International Nuclear Information System (INIS)

    Ziino, G.

    1978-01-01

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

  7. Solute-solvent complex switching dynamics of chloroform between acetone and dimethylsulfoxide-two-dimensional IR chemical exchange spectroscopy.

    Science.gov (United States)

    Kwak, Kyungwon; Rosenfeld, Daniel E; Chung, Jean K; Fayer, Michael D

    2008-11-06

    Hydrogen bonds formed between C-H and various hydrogen bond acceptors play important roles in the structure of proteins and organic crystals, and the mechanisms of C-H bond cleavage reactions. Chloroform, a C-H hydrogen bond donor, can form weak hydrogen-bonded complexes with acetone and with dimethylsulfoxide (DMSO). When chloroform is dissolved in a mixed solvent consisting of acetone and DMSO, both types of hydrogen-bonded complexes exist. The two complexes, chloroform-acetone and chloroform-DMSO, are in equilibrium, and they rapidly interconvert by chloroform exchanging hydrogen bond acceptors. This fast hydrogen bond acceptor substitution reaction is probed using ultrafast two-dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy. Deuterated chloroform is used in the experiments, and the 2D-IR spectrum of the C-D stretching mode is measured. The chemical exchange of the chloroform hydrogen bonding partners is tracked by observing the time-dependent growth of off-diagonal peaks in the 2D-IR spectra. The measured substitution rate is 1/30 ps for an acetone molecule to replace a DMSO molecule in a chloroform-DMSO complex and 1/45 ps for a DMSO molecule to replace an acetone molecule in a chloroform-acetone complex. Free chloroform exists in the mixed solvent, and it acts as a reactive intermediate in the substitution reaction, analogous to a SN1 type reaction. From the measured rates and the equilibrium concentrations of acetone and DMSO, the dissociation rates for the chloroform-DMSO and chloroform-acetone complexes are found to be 1/24 ps and 1/5.5 ps, respectively. The difference between the measured rate for the complete substitution reaction and the rate for complex dissociation corresponds to the diffusion limited rate. The estimated diffusion limited rate agrees well with the result from a Smoluchowski treatment of diffusive reactions.

  8. Antimicrobial potential and phyto chemical analysis of different solvent extracted samples of viola pilosa

    International Nuclear Information System (INIS)

    Bakht, J.; Panni, M. K.; Shafi, M.

    2017-01-01

    Investigation of susceptibility of medicinal plants for bacterial pathogens is significant for suitable choice of treatment. Different solvent extracted samples of Viola pilosa shoots were investigated for their antibacterial and phytochemical activities using 0.5, 1 and 2 mg disc-1 concentrations. The antibacterial bioassay was assayed by disc diffusion method against six microbes. The studies revealed that ethyl acetate extracted fractions resulted in maximum growth inhibition of Pseudomonas aeruginosa and Staphylococcus aureus at 2000 mu g disc-1 concentration. Similarly, Xanthomonas campestris and Klebsiella pneumonia were found more susceptible to n-butanol extract. Maximum reduction in the activity of B. subtilis and E. coli was recorded by n-hexane fractions at two mg per disc. The most susceptible microbe was Pseudomonas aeruginosa. The results further revealed that all the tested microbes were found completely resistant to water extracted fractions at all the tested concentrations measuring 0% ZI. Phytochemical analysis showed the presence of various bioactive compounds including flavonoids, glycosides, proteins, fats, alkaloids, steroids, saponins, carbohydrates and tannins. (author)

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

    Indian Academy of Sciences (India)

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

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

    Directory of Open Access Journals (Sweden)

    Pégot Bruce

    2006-09-01

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

  11. Photoexcitation circular dichroism in chiral molecules

    Science.gov (United States)

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

    2018-05-01

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

  12. A Novel Mechanism for Chemical Sensing Based on Solvent-Fluorophore-Substrate Interaction: Highly Selective Alcohol and Water Sensor with Large Fluorescence Signal Contrast.

    Science.gov (United States)

    Chung, Kyeongwoon; Yang, Da Seul; Jung, Jaehun; Seo, Deokwon; Kwon, Min Sang; Kim, Jinsang

    2016-10-06

    Differentiation of solvents having similar physicochemical properties, such as ethanol and methanol, is an important issue of interest. However, without performing chemical analyses, discrimination between methanol and ethanol is highly challenging due to their similarity in chemical structure as well as properties. Here, we present a novel type of alcohol and water sensor based on the subtle differences in interaction among solvent analytes, fluorescent organic molecules, and a mesoporous silica gel substrate. A gradual change in the chemical structure of the fluorescent diketopyrrolopyrrole (DPP) derivatives alters their interaction with the substrate and solvent analyte, which creates a distinct intermolecular aggregation of the DPP derivatives on the silica gel substrate depending on the solvent environment and produces a change in the fluorescence color and intensity as a sensory signal. The devised sensor device, which is fabricated with simple drop-casting of the DPP derivative solutions onto a silica gel substrate, exhibited a completely reversible fluorescence signal change with large fluorescence signal contrast, which allows selective solvent detection by simple optical observation with the naked eye under UV light. Superior selectivity of the alcohol and water sensor system, which can clearly distinguish among ethanol, methanol, ethylene glycol, and water, is demonstrated.

  13. Isoparaffin diluents for tri-n-butyl phosphate. Chemical, radiation-chemical stability, effect on solvent extraction of tetravalet plutonium and thorium

    International Nuclear Information System (INIS)

    Renard, Eh.V.; Pyatibratov, Yu.P.; Neumoev, N.V.

    1988-01-01

    45-90% conversion degree of n-paraffin into branched isoparaffin with mono- and dimethyl structure is achieved by means of catalytic hydroisomerization of n-paraffin raw material in reactor with alumoplatinum catalyser. Isoparaffin (99%) concentrates with constant molecular mass from iso-C 10 to iso-C 15 are produced of a batch of deeply isomerized n-paraffins. Plutonium and thorum nitrate solubility in 30% TBP solutions in iso-paraffins (iso-paraffin mixtures with similar C atom number) increases with the reduction of iso-paraffin molecular mass; system with 30% TBP in isodecane mixture is practically not stratified (∼ 104 g Pu/l, 22-25 deg C). By the main requirements to diluents for radiochemical extraction operations, including density, viscosity, boiling point flashed and freezines, chemical and radiation stability, radioruthenium and radiozirconium confinement systems, synthetic isoparaffin-containing solvents are as good as n-paraffins

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

    Science.gov (United States)

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

    2018-02-27

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

  15. Production of 13C by chemical exchange reaction between amine carbamate and carbon dioxide in a solvent-carrier system

    International Nuclear Information System (INIS)

    Ghate, M.R.; Taylor, T.I.

    1975-01-01

    The chemical exchange reaction between amine carbamate and CO 2 has been investigated for the purpose of using it as a practical method to concentrate 13 C. The effects of solvent, concentration of amines, catalysts, flow rate, and diameter of the column have been studied for a number of amines. Of the solutions studied, di-n-butylamine (DNBA) in triethylamine (TEA) as a solvent proved to be the most favorable for use in the preparation of highly enriched 13 C. The overall separations obtained as a function of the concentration of DNBA using 2.5 cm i.d. x 100 cm column ranged from 2.05 at 1 M to 1.69 at 2.84 M. For 2 M DNBA the maximum separation was 1.94. At this concentration of DNBA the overall separation as a function of flow rate ranged from 1.94 at 0.845 ml/cm 2 -min to 1.31 at 2.9 ml/cm 2 -min. Neither the rate of exchange nor the overall separations were improved by use of catalysts. Increasing the diameter twofold resulted in little or no loss in overall separations. On the basis of the properties of the system and the data obtained with respect to the above variables, design calculations were made for a six-stage tapered cascade. These calculations were based on a flow of 40 ml/min of 2 M DNBA in TEA, giving a maximum transport of 7.1 x 10 -3 mmole/min or a maximum production rate of 130 mg 13 C/day. The cascade was operated for about 5 months during which period gram quantities of 67 percent 13 C were produced

  16. A new approach towards biomarker selection in estimation of human exposure to chiral chemicals: a case study of mephedrone.

    Science.gov (United States)

    Castrignanò, Erika; Mardal, Marie; Rydevik, Axel; Miserez, Bram; Ramsey, John; Shine, Trevor; Pantoș, G Dan; Meyer, Markus R; Kasprzyk-Hordern, Barbara

    2017-11-02

    Wastewater-based epidemiology is an innovative approach to estimate public health status using biomarker analysis in wastewater. A new compound detected in wastewater can be a potential biomarker of an emerging trend in public health. However, it is currently difficult to select new biomarkers mainly due to limited human metabolism data. This manuscript presents a new framework, which enables the identification and selection of new biomarkers of human exposure to drugs with scarce or unknown human metabolism data. Mephedrone was targeted to elucidate the assessment of biomarkers for emerging drugs of abuse using a four-step analytical procedure. This framework consists of: (i) identification of possible metabolic biomarkers present in wastewater using an in-vivo study; (ii) verification of chiral signature of the target compound; (iii) confirmation of human metabolic residues in in-vivo/vitro studies and (iv) verification of stability of biomarkers in wastewater. Mephedrone was selected as a suitable biomarker due to its high stability profile in wastewater. Its enantiomeric profiling was studied for the first time in biological and environmental matrices, showing stereoselective metabolism of mephedrone in humans. Further biomarker candidates were also proposed for future investigation: 4'-carboxy-mephedrone, 4'-carboxy-normephedrone, 1-dihydro-mephedrone, 1-dihydro-normephedrone and 4'-hydroxy-normephedrone.

  17. Macroscopic chirality of a liquid crystal from nonchiral molecules

    International Nuclear Information System (INIS)

    Jakli, A.; Nair, G. G.; Lee, C. K.; Sun, R.; Chien, L. C.

    2001-01-01

    The transfer of chirality from nonchiral polymer networks to the racemic B2 phase of nonchiral banana-shaped molecules is demonstrated. This corresponds to the transfer of chirality from an achiral material to another achiral material. There are two levels of chirality transfers. (a) On a microscopic level the presence of a polymer network (chiral or nonchiral) favors a chiral state over a thermodynamically stable racemic state due to the inversion symmetry breaking at the polymer-liquid crystal interfaces. (b) A macroscopically chiral (enantimerically enriched) sample can be produced if the polymer network has a helical structure, and/or contains chemically chiral groups. The chirality transfer can be locally suppressed by exposing the liquid crystal to a strong electric field treatment

  18. Significant Enhancement of the Chiral Correlation Length in Nematic Liquid Crystals by Gold Nanoparticle Surfaces Featuring Axially Chiral Binaphthyl Ligands.

    Science.gov (United States)

    Mori, Taizo; Sharma, Anshul; Hegmann, Torsten

    2016-01-26

    Chirality is a fundamental scientific concept best described by the absence of mirror symmetry and the inability to superimpose an object onto its mirror image by translation and rotation. Chirality is expressed at almost all molecular levels, from single molecules to supramolecular systems, and present virtually everywhere in nature. Here, to explore how chirality propagates from a chiral nanoscale surface, we study gold nanoparticles functionalized with axially chiral binaphthyl molecules. In particular, we synthesized three enantiomeric pairs of chiral ligand-capped gold nanoparticles differing in size, curvature, and ligand density to tune the chirality transfer from nanoscale solid surfaces to a bulk anisotropic liquid crystal medium. Ultimately, we are examining how far the chirality from a nanoparticle surface reaches into a bulk material. Circular dichroism spectra of the gold nanoparticles decorated with binaphthyl thiols confirmed that the binaphthyl moieties form a cisoid conformation in isotropic organic solvents. In the chiral nematic liquid crystal phase, induced by dispersing the gold nanoparticles into an achiral anisotropic nematic liquid crystal solvent, the binaphthyl moieties on the nanoparticle surface form a transoid conformation as determined by imaging the helical twist direction of the induced cholesteric phase. This suggests that the ligand density on the nanoscale metal surfaces provides a dynamic space to alter and adjust the helicity of binaphthyl derivatives in response to the ordering of the surrounding medium. The helical pitch values of the induced chiral nematic phase were determined, and the helical twisting power (HTP) of the chiral gold nanoparticles calculated to elucidate the chirality transfer efficiency of the binaphthyl ligand capped gold nanoparticles. Remarkably, the HTP increases with increasing diameter of the particles, that is, the efficiency of the chirality transfer of the binaphthyl units bound to the nanoparticle

  19. Biocatalytic Synthesis of Chiral Pharmaceutical Intermediates

    Directory of Open Access Journals (Sweden)

    Ramesh N. Patel

    2004-01-01

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

  20. Comparison of experimental and DFT-calculated NMR chemical shifts of 2-amino and 2-hydroxyl substituted phenyl benzimidazoles, benzoxazoles and benzothiazoles in four solvents using the IEF-PCM solvation model.

    Science.gov (United States)

    Pierens, Gregory K; Venkatachalam, T K; Reutens, David C

    2016-04-01

    A comparative study of experimental and calculated NMR chemical shifts of six compounds comprising 2-amino and 2-hydroxy phenyl benzoxazoles/benzothiazoles/benzimidazoles in four solvents is reported. The benzimidazoles showed interesting spectral characteristics, which are discussed. The proton and carbon chemical shifts were similar for all solvents. The largest chemical shift deviations were observed in benzene. The chemical shifts were calculated with density functional theory using a suite of four functionals and basis set combinations. The calculated chemical shifts revealed a good match to the experimentally observed values in most of the solvents. The mean absolute error was used as the primary metric. The use of an additional metric is suggested, which is based on the order of chemical shifts. The DP4 probability measures were also used to compare the experimental and calculated chemical shifts for each compound in the four solvents. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Modification of the twist angle in chiral nematic polymer films by photoisomerization of the chiral dopant

    NARCIS (Netherlands)

    Witte, van de P.; Neuteboom, E.E.; Brehmer, M.; Lub, Johan

    1999-01-01

    A method for the production of polarization sensitive recordings in liquid crystalline polymers is presented. The system is based on local modification of the twist angle of chiral nematic polymer films. The twist angle of the polymer film is varied by modifying the chemical structure of the chiral

  2. Chiral symmetry and chiral-symmetry breaking

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1982-12-01

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

  3. Investigation of degradation products produced by recycling the solvent during chemical degradation of fiber-reinforced composites

    DEFF Research Database (Denmark)

    Ucar, Hülya; Simonsen, Morten Enggrob; Søgaard, Erik Gydesen

    2017-01-01

    of the process. In this study, acetone has been used as the organic solvent. To increase the sustainability of the process, the solvent was recycled in eight consecutive batches using new glass fiber-reinforced composites in each recycling. No additional amount of acetone was added, resulting in a reduction...

  4. Chiral mirrors

    International Nuclear Information System (INIS)

    Plum, Eric; Zheludev, Nikolay I.

    2015-01-01

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

  5. A Multidisciplinary Approach Toward the Rapid and Preparative-Scale Biocatalytic Synthesis of Chiral Amino Alcohols: A Concise Transketolase-/omega-Transaminase-Mediated Synthesis of (2S,3S)-2-Aminopentane-1,3-diol

    DEFF Research Database (Denmark)

    Smith, M.E.B; Chen, B.H.; Hibbert, E.G

    2010-01-01

    Chiral amino alcohols represent an important class of value-added biochemicals and pharmaceutical intermediates. Chemical routes to such compounds are generally step intensive, requiring environmentally unfriendly catalysts and solvents. This work describes a multidisciplinary approach to the rapid...... the bioconversions were subsequently scaled up to preparative scales in batch stirred-tank reactors. The microwell methods thus provide process chemists and engineers with a valuable tool for the rapid and early evaluation of potential synthetic strategies. Overall, this work describes a concise and efficient...... biocatalytic route to chiral amino alcohols and illustrates an integrated multidisciplinary approach to bioconversion process design and scale-up....

  6. Impact of TiO2 on the chemical and biological transformation of formulated chiral-metalaxyl in agricultural soils.

    Science.gov (United States)

    Huang, Junxing; Zhang, Xu; Liang, Chuanzhou; Hu, Jun

    2018-04-15

    The impacts of TiO 2 on the chemical and biological transformation of racemic metalaxyl wettable powder (rac-metalaxyl WP) in agricultural soils, and soil microorganisms were investigated. Under simulated solar irradiation, TiO 2 highly promoted the transformation of rac-metalaxyl WP without changing the enantiomer fraction, with the promotion amplitude (60-1280%) being dependent on TiO 2 characteristics. TiO 2 characteristics showed different influence on the transformation of rac-metalaxyl WP in soils and aqueous solutions because their characteristics changed differently in soils. The impact of the mancozeb and other co-constituents on the transformation of rac-metalaxyl WP was smaller in soil media than in aqueous solution. Autoclave sterilization changed soil properties and subsequently weakened the promotion effects of TiO 2 on the chemical transformations of rac-metalaxyl WP to 0-233%. Microorganism biomass and bacterial community were not statistically significant changed by TiO 2 exposure regardless of rac-metalaxyl WP, suggesting that the promotional effects occurred mainly through chemical processes. The results also showed TiO 2 -soil interactions may be strengthened with TiO 2 (Degussa P25) aging time in soils, which decreased its promotion amplitude from 1060% (without aging) to 880% (aging for 20 days). Intermediate formed in soil biological transformation process was different from that in TiO 2 photocatalysis process. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Chirality sensing with stereodynamic biphenolate zinc complexes.

    Science.gov (United States)

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

    2015-10-01

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

  8. Chirality detection of enantiomers using twisted optical metamaterials

    Science.gov (United States)

    Zhao, Yang; Askarpour, Amir N.; Sun, Liuyang; Shi, Jinwei; Li, Xiaoqin; Alù, Andrea

    2017-01-01

    Many naturally occurring biomolecules, such as amino acids, sugars and nucleotides, are inherently chiral. Enantiomers, a pair of chiral isomers with opposite handedness, often exhibit similar physical and chemical properties due to their identical functional groups and composition, yet show different toxicity to cells. Detecting enantiomers in small quantities has an essential role in drug development to eliminate their unwanted side effects. Here we exploit strong chiral interactions with plasmonic metamaterials with specifically designed optical response to sense chiral molecules down to zeptomole levels, several orders of magnitude smaller than what is typically detectable with conventional circular dichroism spectroscopy. In particular, the measured spectra reveal opposite signs in the spectral regime directly associated with different chiral responses, providing a way to univocally assess molecular chirality. Our work introduces an ultrathin, planarized nanophotonic interface to sense chiral molecules with inherently weak circular dichroism at visible and near-infrared frequencies. PMID:28120825

  9. Analysis of epoxyeicosatrienoic acids by chiral liquid chromatography/electron capture atmospheric pressure chemical ionization mass spectrometry using [13C]-analog internal standards

    Science.gov (United States)

    Mesaros, Clementina; Lee, Seon Hwa; Blair, Ian A.

    2012-01-01

    The metabolism of arachidonic acid (AA) to epoxyeicosatrienoic acids (EETs) is thought to be mediated primarily by the cytochromes P450 (P450s) from the 2 family (2C9, 2C19, 2D6, and 2J2). In contrast, P450s of the 4 family are primarily involved in omega oxidation of AA (4A11 and 4A22). The ability to determine enantioselective formation of the regioisomeric EETs is important in order to establish their potential biological activities and to asses which P450 isoforms are involved in their formation. It has been extremely difficult to analyze individual EET enantiomers in biological fluids because they are present in only trace amounts and they are extremely difficult to separate from each other. In addition, the deuterium-labeled internal standards that are commonly used for stable isotope dilution liquid chromatography/mass spectrometry (LC/MS) analyses have different LC retention times when compared with the corresponding protium forms. Therefore, quantification by LC/MS-based methodology can be compromised by differential suppression of ionization of the closely eluting isomers. We report the preparation of [13C20]-EET analog internal standards and the use of a validated high-sensitivity chiral LC/electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the trace analysis of endogenous EETs as their pentafluorobenzyl (PFB) ester derivatives. The assay was then used to show the exquisite enantioselectivity of P4502C19-, P4502D6-, P4501A1-, and P4501B1-mediated conversion of AA into EETs and to quantify the enantioselective formation of EETs produced by AA metabolism in a mouse epithelial hepatoma (Hepa) cell line. PMID:20972997

  10. Chiral Magnetic Spirals

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  11. Introduction to Chiral Symmetry

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-09

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

  12. Introduction to chiral symmetry

    International Nuclear Information System (INIS)

    Koch, V.

    1996-01-01

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

  13. Physico-chemical properties of binary mixtures of aliphatic and aromatic solvents at 313 K on acoustical data

    Science.gov (United States)

    Dahire, S. L.; Morey, Y. C.; Agrawal, P. S.

    2015-12-01

    Density (ρ), viscosity (η), and ultrasonic velocity ( U) of binary mixtures of aliphatic solvents like dimethylformamide (DMF) and dimethylsulfoxide (DMSO) with aromatic solvents viz. chlorobenzene (CB), bromobenzene (BB), and nitrobenzene (NB) have been determined at 313 K. These parameters were used to calculate the adiabatic compressibility (β), intermolecular free length ( L f), molar volume ( V m), and acoustic impedance ( Z). From the experimental data excess molar volume ( V m E ), excess intermolecular free length ( L f E )), excess adiabatic compressibility (βE), and excess acoustic impedance ( Z E) have been computed. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations (σ).

  14. Chiral discotics; expression and amplification of chirality

    NARCIS (Netherlands)

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

    2003-01-01

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

  15. Chemical Speciation and Bond Lengths of Organic Solutes by Core-Level Spectroscopy: pH and Solvent Influence on p-Aminobenzoic Acid.

    Science.gov (United States)

    Stevens, Joanna S; Gainar, Adrian; Suljoti, Edlira; Xiao, Jie; Golnak, Ronny; Aziz, Emad F; Schroeder, Sven L M

    2015-05-04

    Through X-ray absorption and emission spectroscopies, the chemical, electronic and structural properties of organic species in solution can be observed. Near-edge X-ray absorption fine structure (NEXAFS) and resonant inelastic X-ray scattering (RIXS) measurements at the nitrogen K-edge of para-aminobenzoic acid reveal both pH- and solvent-dependent variations in the ionisation potential (IP), 1s→π* resonances and HOMO-LUMO gap. These changes unequivocally identify the chemical species (neutral, cationic or anionic) present in solution. It is shown how this incisive chemical state sensitivity is further enhanced by the possibility of quantitative bond length determination, based on the analysis of chemical shifts in IPs and σ* shape resonances in the NEXAFS spectra. This provides experimental access to detecting even minor variations in the molecular structure of solutes in solution, thereby providing an avenue to examining computational predictions of solute properties and solute-solvent interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Asymmetric Michael Addition Mediated by Chiral Ionic Liquids

    Science.gov (United States)

    Suzuki, Yumiko

    2018-01-01

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

  17. Asymmetric Michael Addition Mediated by Chiral Ionic Liquids.

    Science.gov (United States)

    Suzuki, Yumiko

    2018-06-01

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

  18. The solvent effect on the enthalpy of hydrolysis of cyclic adenosine 3',5'-monophosphate : a quantum chemical study

    NARCIS (Netherlands)

    Scheffers - Sap, Miek; Buck, H.M.

    1978-01-01

    The solvent effect on the enthalpy of hydrolysis has been studied by the Extended-Hückel method for the hydrolysis reactions of cyclic adenosine 3',5'-monophosphate (cyclic 3',5'-AMP) and related cyclic phosphate diesters. The results show that the difference in enthalpy of hydrolysis between cyclic

  19. Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

    International Nuclear Information System (INIS)

    Guo Zhen; Liu Xianbin; Ng, Siu-Choon; Chen Yuan; Yang Yanhui; Du Yu

    2010-01-01

    Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

  20. Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

    Energy Technology Data Exchange (ETDEWEB)

    Guo Zhen; Liu Xianbin; Ng, Siu-Choon; Chen Yuan; Yang Yanhui [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459 (Singapore); Du Yu, E-mail: du_yu@jlu.edu.cn, E-mail: yhyang@ntu.edu.sg [College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2010-04-23

    Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

  1. 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)

  2. On chiral and non chiral 1D supermultiplets

    International Nuclear Information System (INIS)

    Toppan, Francesco

    2011-01-01

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

  3. Analysis of vitamin K-1 in fruits and vegetables using accelerated solvent extraction and liquid chromatography tandem mass spectrometry with atmospheric pressure chemical ionization

    DEFF Research Database (Denmark)

    Jäpelt, Rie Bak; Jakobsen, Jette

    2016-01-01

    The objective of this study was to develop a rapid, sensitive, and specific analytical method to study vitamin K-1 in fruits and vegetables. Accelerated solvent extraction and solid phase extraction was used for sample preparation. Quantification was done by liquid chromatography tandem mass...... spectrometry with atmospheric pressure chemical ionization in selected reaction monitoring mode with deuterium-labeled vitamin K1 as an internal standard. The precision was estimated as the pooled estimate of three replicates performed on three different days for spinach, peas, apples, banana, and beetroot...

  4. Application of volt-chins for determination of ionic components in real and chemical Gibbs transition energies of individual ions from water in aqueous-organic solvents

    International Nuclear Information System (INIS)

    Parfenyuk, V.I.

    2007-01-01

    Thermodynamic description of separate ions (among which is I - ) in individual and mixed solvents is conducted on the basis of the volt potential difference method. Application of the presented methodology serves as one of candidates problem solving of individual ions thermodynamic characterisation in solutions. Validity of application of the volt potential difference method for the determination of ionic components in real and chemical thermodynamic properties of separate ions in solutions as well as surface potential values on the solution-gas phase interfaces is demonstrated [ru

  5. Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory

    Energy Technology Data Exchange (ETDEWEB)

    Rogachevskii, Igor; Kleeorin, Nathan [Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Ruchayskiy, Oleg [Discovery Center, Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Boyarsky, Alexey [Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Fröhlich, Jürg [Institute of Theoretical Physics, ETH Hönggerberg, CH-8093 Zurich (Switzerland); Brandenburg, Axel; Schober, Jennifer, E-mail: gary@bgu.ac.il [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)

    2017-09-10

    The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right- and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma ( chiral magnetic effect ). We present a self-consistent treatment of the chiral MHD equations , which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that the chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the large-scale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark–gluon plasma.

  6. Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory

    International Nuclear Information System (INIS)

    Rogachevskii, Igor; Kleeorin, Nathan; Ruchayskiy, Oleg; Boyarsky, Alexey; Fröhlich, Jürg; Brandenburg, Axel; Schober, Jennifer

    2017-01-01

    The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right- and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma ( chiral magnetic effect ). We present a self-consistent treatment of the chiral MHD equations , which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that the chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the large-scale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark–gluon plasma.

  7. Ionic Liquids Beyond Simple Solvents: Glimpses at the State of the Art in Organic Chemistry.

    Science.gov (United States)

    Kuchenbuch, Andrea; Giernoth, Ralf

    2015-12-01

    Within the last 25 years ionic liquids have written a tremendous success story, which is documented in a nearly uncountable amount of original research papers, reviews, and numerous applications in research and industry. These days, ionic liquids can be considered as a mature class of compounds for many different applications. Frequently, they are used as neoteric solvents for chemical tansformations, and the number of reviews on this field of research is huge. In this focused review, though, we are trying to evaluate the state of the art of ionic liquid chemistry beyond using them simply as solvents for chemical transformations. It is not meant to be a comprehensive overview on the topic; the choice of emphasis and examples rather refects the authors' personal view on the field. We are especially highlighting fields in which we believe the most fundamental developments within the next five years will take place: biomass processing, (chiral) ionic liquids from natural sources, biotransformations, and organic synthesis.

  8. DESIGNING GREENER SOLVENTS

    Science.gov (United States)

    Computer-aided design of chemicals and chemical mixtures provides a powerful tool to help engineers identify cleaner process designs and more-benign alternatives to toxic industrial solvents. Three software programs are discussed: (1) PARIS II (Program for Assisting the Replaceme...

  9. 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.

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

    Science.gov (United States)

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

    2014-08-14

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

  11. Mechanical separation of chiral dipoles by chiral light

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  12. Some remarks on chiral symmetry in dense matter

    International Nuclear Information System (INIS)

    Kaellman, C.G.; Montonen, C.

    1982-01-01

    The restoration of chiral symmetry in quantum chromodynamics as the temperature T and the chemical potential vertical stroke μ vertical stroke are increased is discussed qualitatively and using effective field theories. The latter are shown not to give reliable quantitative estimates. It is argued that a dilute gas of instantons cannot be the main dynamical agent responsible for the breakdown of chiral symmetry. (orig.)

  13. Investigation of Chirality Selection Mechanism of Single-Walled Carbon Nanotube

    Science.gov (United States)

    2015-07-17

    Final 3. DATES COVERED (From - To) 01-June-2014 to 31-May-2015 4. TITLE AND SUBTITLE Investigation of Chirality Selection Mechanism of...of two significant mechanistic aspects of carbon nanotube (CNT) array growth under chemical vapor deposition conditions: chirality selectivity and...affected by the morphological evolution of catalyst particles. 15. SUBJECT TERMS Carbon Nanotubes, Chirality , Processing, Catalysis

  14. Active chiral fluids.

    Science.gov (United States)

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

    2012-09-01

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

  15. Solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, D.M.; Latimer, E.G.

    1988-01-05

    It is an object of this invention to provide for the demetallization and general upgrading of heavy oil via a solvent extracton process, and to improve the efficiency of solvent extraction operations. The yield and demetallization of product oil form heavy high-metal content oil is maximized by solvent extractions which employ either or all of the following techniques: premixing of a minor amount of the solvent with feed and using countercurrent flow for the remaining solvent; use of certain solvent/free ratios; use of segmental baffle tray extraction column internals and the proper extraction column residence time. The solvent premix/countercurrent flow feature of the invention substantially improves extractions where temperatures and pressures above the critical point of the solvent are used. By using this technique, a greater yield of extract oil can be obtained at the same metals content or a lower metals-containing extract oil product can be obtained at the same yield. Furthermore, the premixing of part of the solvent with the feed before countercurrent extraction gives high extract oil yields and high quality demetallization. The solvent/feed ratio features of the invention substanially lower the captial and operating costs for such processes while not suffering a loss in selectivity for metals rejection. The column internals and rsidence time features of the invention further improve the extractor metals rejection at a constant yield or allow for an increase in extract oil yield at a constant extract oil metals content. 13 figs., 3 tabs.

  16. Chirality induction and protonation-induced molecular motions in helical molecular strands.

    Science.gov (United States)

    Kolomiets, Elena; Berl, Volker; Lehn, Jean-Marie

    2007-01-01

    The long oligopyridinedicarboxamide strand 9, containing 15 heterocyclic rings has been synthesized and its helical structure determined by X-ray crystallography. It was shown that the shorter analogue 6 displays induced circular dichroism and amplification of induced chirality upon dissolution in an optically active solvent, diethyl-L-tartrate. A novel class of helical foldamers was prepared, strands 14-16, based on two oligopyridine carboxamide segments linked through a L-tartaric acid derived spacer. These tartro strands display internal chirality induction as well as chirality amplification. NMR spectroscopy (on 8 and 9) and circular dichroism (on 16) studies show that the oligopyridine carboxamide strands undergo reversible unfolding/folding upon protonation. The protonation-induced unfolding has been confirmed by X-ray crystallographic determination of the molecular structure of the extended protonated heptameric form 8(+). The molecular-scale mechano-chemical motions of the protonation-induced structural switching consist of a change of the length of the molecule, from 6 angstroms (6, coiled form) to 29 angstroms (8(+), uncoiled form) for the heptamer and from 12.5 angstroms (9, coiled form, X-ray structure) to 57 angstroms (9(+), uncoiled form, from modeling) for the pentadecamer. Similar unfolding/folding motional processes take place in the L-tartro strands 15 and 16 upon protonation/deprotonation, with loss of helicity-induced circular dichroism on unfolding as shown for the protonated form 16(+).

  17. Chemical Equilibrium and Synergism for Solvent Extraction of Trace Lithium with Thenoyltrifluoroacetone in the Presence of Trioctylphosphine Oxide

    International Nuclear Information System (INIS)

    Kim, Young Sang; In, Gyo; Choi, Jong Moon

    2003-01-01

    Equilibria and applications of a synergistic extraction were studied for the determination of a trace lithium by using thenoyltrifluoroacetone (TTA) and trioctylphosphine oxide (TOPO) as ligands. Several equations were derived for the extraction of lithium into m-xylene as a phase of Li-TTA·mTOPO adduct. Distribution coefficients and extraction constant were determined together with a stability constant of the adduct. The adduct was quantitatively extracted from the basic solution of higher than pH 9 by shaking for 30 minutes. m- Xylene was selected as an optimum solvent by comparing the extraction efficiency among several kinds of organic solvents. The stability constant (β 2 ) for Li-TTA/2TOPO was 150 times higher than Li-TTA/TOPO. The distribution coefficient of Li-TTA/2TOPO into m-xylene was 9.12 and the logarithmic extraction constant (log Kex) was 6.76. Trace lithium of sub-ppm level in seawater samples could be determined under modified conditions and a detection limit equivalent to 3 times standard deviation for background absorption was 0.42 ng/mL

  18. Chemical and biological characterisation of solvent extracts and essential oils from leaves and fruit of two Australian species of Pittosporum (Pittosporaceae) used in aboriginal medicinal practice.

    Science.gov (United States)

    Sadgrove, Nicholas John; Jones, Graham Lloyd

    2013-02-13

    antimicrobial activity whilst the other chemotype had only moderate antimicrobial activity against the three microbial species investigated here. This result may support the occurrence of geographical specificity with regard to ethnopharmacological use. Antimicrobial activity screening of the solvent extracts from Pittosporum angustifolium revealed the leaves to be superior to fruit, with water being the most suitable extraction solvent. To the best of our knowledge, this study constitutes the first time essential oils, and solvent extracts from the fruits of Pittosporum angustifolium, have been examined employing comprehensive chemical and biological analysis. The essential oil composition presented in this paper, includes components with structural similarity as chemosemiotic compounds involved in mother-infant identification, which may have significance with regard to traditional applications as a lactagogue. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  19. DETERMINATION OF SOME PHYSICAL AND CHEMICAL PROPERTIES OF PECTIN SUBSTANCES FROM THE SOLVENT CAKE OF TAGETES PATULA L. INFLORESCENCES

    Directory of Open Access Journals (Sweden)

    N. M. Chervonnaya

    2017-01-01

    Full Text Available Big molecular weight conditions are responsible for some properties, which are absent in low molecular compounds. Therefore, its determination allows revealing of some physical and technological properties of biopolymers and prediction of the possibility of their practical application. The aim of this work was to determine an average molarweight, to study the superficial properties at the border of “solution-air” phases, and to establish an isoelectric spot of water solutions of pectin substances (PS, isolated from a solvent cake of Tagetes patula inflorescences. Materials and methods. Polysaccharide complexes were isolated from the solvent cake of Tagetes patula inflorescences of Carmen species which was left after a raw material extraction with ethanol 40% with the method of Kochetkov and M. Sinnera. The time of water and PS solutions flow out was measured by the use of a capillary Ostwald viscosimeter; different types of viscosity were calculated. The density of solutions was determined by using a picnometric method, however due to the closeness of density of the analyzed solutions and water, they were not considered in the calculation of the relative viscosity. Series of solutions with 0.01 to 0.5% concentrations were prepared from 1% PS water solutions to determine a surface activity. Monometric liquid tension variations were set in Rehbinder’s apparatus in the moment of an air bubble appearance on the surface of PS solution. Isoelectric spot (IES of PS was determined in acetate buffer solution with pH within 3.2 to 6.2 by using the viscometer method. Results and discussion. Fractioning of the obtained polysaccharide complexes showed that efficiency of the pectin substances amounted to 2.2%. Calculation shows that an average molar weight of PS amounted to 45272 g/mol. About the degree of interaction between macromolecules of polymer and solvent, structural properties of macromolecule, the degree of its branching can be judged by the

  20. Methods and instruments for the ecological assessment of the treatment of solvent wastes in the chemical industry; Methoden und Instrumente zur oekologischen Bewertung der Abfall-Loesungsmittelbehandlung in der chemischen Industrie

    Energy Technology Data Exchange (ETDEWEB)

    Capello, Ch.

    2006-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a project which looked at the treatment of solvent wastes in the chemical industry and its ecological impact. The development of a method based on the life-cycle-analysis (LCA) approach is described. The LCA methodology is to provide support for decision-making in the area of solvent waste disposal in the chemical industry. Various methods of disposal, such as distillation or incineration are looked at. The results of calculations using a software tool called 'ecosolvent' are presented and discussed. The 15 most important solvents and their quantities as used in the 6 facilities examined, are listed. The functioning of the ecosolvent software is discussed and illustrated in a flow-diagram. Along with detailed results, a few qualitative rules of thumb are quoted for the treatment of solvent wastes.

  1. Chiral separation and chemical profile of Dengzhan Shengmai by integrating comprehensive with multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Sheng, Ning; Zheng, Hao; Xiao, Yao; Wang, Zhe; Li, Menglin; Zhang, Jinlan

    2017-09-29

    Chemical profile for Chinese medicine formulas composed of several herbs is always a challenge due to a big array of small molecules with high chemical diversity so much as isomers. The present paper develops a feasible strategy to characterize and identify complex chemical constituents of a four-herb traditional Chinese medicine formula, Denzhan Shenmai (DZSM) by integrating comprehensive two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC×LC-qTOF-MS) with multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (MHC-qTOF-MS). DZSM was separated by C8×C18 HPLC column system for comprehensive two-dimensional liquid chromatography system and 283 compounds most of which belonged to phenolic acid, flavonoid, saponin and lignan families were characterized and identified within 75min. Some isomers and compounds at low level were analyzed on C8×Chiral HPLC column system for multiple heart-cutting two-dimensional liquid chromatography system with 1D and 2D optimized gradient elution program. These 1D cutting fractions were successively separated on 2D chiral chromatographic column under extended the 2D gradient elution time from 30s to 5.0min. 12 pairs of isomer compounds were separated with good resolution. The combination of LC×LC and MHC system provides a powerful technique for global chemical profiling of DZSM and provided feasible strategy for other complex systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. EXPERIENCE WITH INTRAPERITONEAL CHEMOTHERAPY USING ASCITIC FLUID AS A SOLVENT OF CHEMICALS IN THE TREATMENT OF OVARIAN CANCER

    Directory of Open Access Journals (Sweden)

    Yu. S. Sidorenko

    2009-01-01

    Full Text Available Thirty two with the ascitic form of Stages IIIC—IV ovarian cancer underwent 1 to 3 courses of intraperitoneal multidrug therapy using a protein ascitic fluid concentrate (PAFC as a solvent of drugs (cisplatin, cyclophosphan, doxorubicin according to the CAP regimen. The induction chemotherapy allowed remission to be achieved in 78.1% of cases (against 40% with standard intraperitoneal therapy, the stan- dard volume of surgical treatment was performed in 28 (87.5% patients (21 (70% receiving the control regime; with the use of PAFC, the size of minimum residual tumour (less than 1 cm was achieved in 81.3% versus 63.3% with standard intraperitoneal chemotherapy. This treatment enables the use large-dose chemotherapy regimens that cause no severe systemic toxic reactions. The method is highly-effective, low-toxic and may be recommended for the treatment of patients with the ascitic form of Stages III—IV ovarian cancer.

  3. Chemical modification of chitosan in the absence of solvent for diclofenac sodium removal: pH and kinetics studies

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Kerlaine Alexandre Araujo; Osorio, Luizangela Reis; Silva, Marcos Pereira; Silva Filho, Edson Cavalcanti da, E-mail: edsonfilho@ufpi.edu.br [Universidade Federal do Piaui (UFPI/CCN), Teresina, PI (Brazil). Centro de Ciencias da Natureza. Lab. Interdisciplinar de Materiais Avancados; Sousa, Kaline Soares [Universidade Federal da Paraiba (UFPB/CCEN), Joao Pessoa, PB (Brazil). Centro de Ciencias Exatas e da Natureza. Dept. de Quimica

    2014-08-15

    Chitosan was modified with acetylacetone and ethylenediamine in the absence of solvent. The new biopolymer obtained from the modification was characterized by elemental analysis and NMR 13C and applied in the removal of diclofenac sodium aqueous solution varying the pH and time. Through elemental analysis was possible to verify a decreasing in C/N relation after reaction with acetylacetone and an increasing after modification with ethylenediamine. From NMR analysis was verified the appearance of peaks around 160-210 ppm in both materials due to free carbonyl groups in the first step of the modification, besides the formation of imine bonds. The adsorption tests showed that the highest value occurred at pH 4 and from the results of the kinetic study was found that maximum adsorption occurred within 45 minutes and experimental data adjusted better to linear adjustment, following pseudo second-order model. The results show a material efficient in the removal of emerging pollutants. (author)

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

    Science.gov (United States)

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

    2017-11-01

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

  5. A chiroptical switch based on supramolecular chirality transfer through alkyl chain entanglement and dynamic covalent bonding.

    Science.gov (United States)

    Lv, Kai; Qin, Long; Wang, Xiufeng; Zhang, Li; Liu, Minghua

    2013-12-14

    Chirality transfer is an interesting phenomenon in Nature, which represents an important step to understand the evolution of chiral bias and the amplification of the chirality. In this paper, we report the chirality transfer via the entanglement of the alkyl chains between chiral gelator molecules and achiral amphiphilic Schiff base. We have found that although an achiral Schiff base amphiphile could not form organogels in any kind of organic solvents, it formed co-organogels when mixed with a chiral gelator molecule. Interestingly, the chirality of the gelator molecules was transferred to the Schiff base chromophore in the mixed co-gels and there was a maximum mixing ratio for the chirality transfer. Furthermore, the supramolecular chirality was also produced based on a dynamic covalent chemistry of an imine formed by the reaction between an aldehyde and an amine. Such a covalent bond of imine was formed reversibly depending on the pH variation. When the covalent bond was formed the chirality transfer occurred, when it was destroyed, the transfer stopped. Thus, a supramolecular chiroptical switch is obtained based on supramolecular chirality transfer and dynamic covalent chemistry.

  6. Molecular-Level Design of Heterogeneous Chiral Catalysis

    International Nuclear Information System (INIS)

    Zaera, Francisco

    2012-01-01

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

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

    International Nuclear Information System (INIS)

    Berger, T.

    1992-01-01

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

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

    International Nuclear Information System (INIS)

    Sydorenko, Maksym; Shtanov, Yuri; Tomalak, Oleksandr

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Sydorenko, Maksym; Shtanov, Yuri [Bogolyubov Institute for Theoretical Physics, 03680 Kiev (Ukraine); Tomalak, Oleksandr, E-mail: maxsydorenko@gmail.com, E-mail: tomalak@uni-mainz.de, E-mail: shtanov@bitp.kiev.ua [Institut für Kernphysik, Johannes Gutenberg Universität, 55128 Mainz (Germany)

    2016-10-01

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

  10. Deasphalting solvents

    International Nuclear Information System (INIS)

    Carrillo, J. A; Caceres, J; Vela, G; Bueno, H

    1996-01-01

    This paper describes how the deasphalted oil (DMO) or demetalized oil (DMO) quality (CCR, Ni, V end asphaltenes contents) changes with: DAO or DMO yield, solvent/feed ratio, type of vacuum reside (from paraffinic to blends with vis breaking bottoms), extraction temperature and extraction solvent (propane, propylene, n-butane and I butane)

  11. Observation of chiral phonons

    KAUST Repository

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

    2018-01-01

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

  12. Observation of chiral phonons

    KAUST Repository

    Zhu, Hanyu

    2018-02-01

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

  13. The complete lowest order chiral Lagrangian from a little box

    International Nuclear Information System (INIS)

    DeGrand, T.; Schaefer, S.

    2007-09-01

    We recently performed a pilot study determining the parameters of the leading order chiral Lagrangian from distributions of the eigenvalues of a quenched Dirac operator coupled to an imaginary isospin chemical potential. (orig.)

  14. Stereochemistry of Complex Marine Natural Products by Quantum Mechanical Calculations of NMR Chemical Shifts: Solvent and Conformational Effects on Okadaic Acid

    Directory of Open Access Journals (Sweden)

    Humberto J. Domínguez

    2014-01-01

    Full Text Available Marine organisms are an increasingly important source of novel metabolites, some of which have already inspired or become new drugs. In addition, many of these molecules show a high degree of novelty from a structural and/or pharmacological point of view. Structure determination is generally achieved by the use of a variety of spectroscopic methods, among which NMR (nuclear magnetic resonance plays a major role and determination of the stereochemical relationships within every new molecule is generally the most challenging part in structural determination. In this communication, we have chosen okadaic acid as a model compound to perform a computational chemistry study to predict 1H and 13C NMR chemical shifts. The effect of two different solvents and conformation on the ability of DFT (density functional theory calculations to predict the correct stereoisomer has been studied.

  15. Chiral Spirals from Discontinuous Chiral Symmetry

    Science.gov (United States)

    Kojo, Toru

    2014-09-01

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

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

    OpenAIRE

    Capozziello, S.; Lattanzi, A.

    2004-01-01

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

  17. Solvent substitution

    International Nuclear Information System (INIS)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general ''Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated

  18. Solvent substitution

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  19. Selection and design of solvents

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    and design of solvents will be presented together with application examples. The selection problem is defined as finding known chemicals that match the desired functions of a solvent for a specified set of applications. The design problem is defined as finding the molecular structure (or mixture of molecules....... With increasing interest on issues such as waste, sustainability, environmental impact and green chemistry, the selection and design of solvents have become important problems that need to be addressed during chemical product-process design and development. Systematic methods and tools suitable for selection......) that match the desired functions of a solvent for a specified set of applications. Use of organic chemicals and ionic liquids as solvents will be covered....

  20. Applications of chiral symmetry

    International Nuclear Information System (INIS)

    Pisarski, R.D.

    1995-03-01

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

  1. Organic solvent topical report

    Energy Technology Data Exchange (ETDEWEB)

    Cowley, W.L.

    1998-04-30

    This report is the technical basis for the accident and consequence analyses used in the Hanford Tank Farms Basis for Interim Operation. The report also contains the scientific and engineering information and reference material needed to understand the organic solvent safety issue. This report includes comments received from the Chemical Reactions Subcommittee of the Tank Advisory Panel.

  2. Organic solvent topical report

    International Nuclear Information System (INIS)

    Cowley, W.L.

    1998-01-01

    This report is the technical basis for the accident and consequence analyses used in the Hanford Tank Farms Basis for Interim Operation. The report also contains the scientific and engineering information and reference material needed to understand the organic solvent safety issue. This report includes comments received from the Chemical Reactions Subcommittee of the Tank Advisory Panel

  3. Super oxidation and solidification of organic solvents, polycyclic aromatic hydrocarbons and pesticides at an abandoned chemical factory site

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Kevin; Xu, Paul [Suntime Remediation Company, Changzhou, Jiangsu (China); Loo, Walter [Environment and Technology Services, 1323 Horizon Lane, Patterson, CA 95363 (United States)

    2013-07-01

    Large quantities of organic chemical such as VOCs, SVOCs and POPs were found in the soil of land at an abandoned Chemical Plant. Technology of super oxidation was applied to the soil for cleanup. Fenton process was utilized to treat soil contaminated heavily by BHC, benzene, chlorobenzene, dichlorobenzene, hexachlorobenzene, dichloroethane, dichloropropane, trichlorobenzene and dichloroether, etc. Super oxidation was coupled with method of stabilization for this case to enhance the remediation effect, which proved to be successful. Concentration of concerned pollutants was brought down below the national regulation level by approximately 8 folds. To make the treated soil strong and effective layer preventing pollutants breaking through, Iron powder was mixed in the soil, forming PBR (Permeable Barrier Reactor), to lower the risk to human health. The site after enhanced super oxidation above was totally safe to be developed into a residential community and/or commercial area. (authors)

  4. Chiral bag model

    International Nuclear Information System (INIS)

    Musakhanov, M.M.

    1980-01-01

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

  5. The covariant chiral ring

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-23

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

  6. Spectral signatures of chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

    We present a new way of measuring chirality, via the spectral shift of photonic band gaps in one-dimensional structures. We derive an explicit mapping of the problem of oblique incidence of circularly polarized light on a chiral one-dimensional photonic crystal with negligible index contrast...... to the formally equivalent problem of linearly polarized light incident on-axis on a non-chiral structure with index contrast. We derive analytical expressions for the first-order shifts of the band gaps for negligible index contrast. These are modified to give good approximations to the band gap shifts also...

  7. Chiral near-fields around chiral dolmen nanostructure

    International Nuclear Information System (INIS)

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

    2017-01-01

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

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

    Science.gov (United States)

    Zeng, Chenjie; Jin, Rongchao

    2017-08-04

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

  9. Genetically programmed chiral organoborane synthesis

    Science.gov (United States)

    Kan, S. B. Jennifer; Huang, Xiongyi; Gumulya, Yosephine; Chen, Kai; Arnold, Frances H.

    2017-12-01

    Recent advances in enzyme engineering and design have expanded nature’s catalytic repertoire to functions that are new to biology. However, only a subset of these engineered enzymes can function in living systems. Finding enzymatic pathways that form chemical bonds that are not found in biology is particularly difficult in the cellular environment, as this depends on the discovery not only of new enzyme activities, but also of reagents that are both sufficiently reactive for the desired transformation and stable in vivo. Here we report the discovery, evolution and generalization of a fully genetically encoded platform for producing chiral organoboranes in bacteria. Escherichia coli cells harbouring wild-type cytochrome c from Rhodothermus marinus (Rma cyt c) were found to form carbon-boron bonds in the presence of borane-Lewis base complexes, through carbene insertion into boron-hydrogen bonds. Directed evolution of Rma cyt c in the bacterial catalyst provided access to 16 novel chiral organoboranes. The catalyst is suitable for gram-scale biosynthesis, providing up to 15,300 turnovers, a turnover frequency of 6,100 h-1, a 99:1 enantiomeric ratio and 100% chemoselectivity. The enantiopreference of the biocatalyst could also be tuned to provide either enantiomer of the organoborane products. Evolved in the context of whole-cell catalysts, the proteins were more active in the whole-cell system than in purified forms. This study establishes a DNA-encoded and readily engineered bacterial platform for borylation; engineering can be accomplished at a pace that rivals the development of chemical synthetic methods, with the ability to achieve turnovers that are two orders of magnitude (over 400-fold) greater than those of known chiral catalysts for the same class of transformation. This tunable method for manipulating boron in cells could expand the scope of boron chemistry in living systems.

  10. Proton triggered circularly polarized luminescence in orthogonal- and co-assemblies of chiral gelators with achiral perylene bisimide.

    Science.gov (United States)

    Han, Dongxue; Han, Jianlei; Huo, Shengwei; Qu, Zuoming; Jiao, Tifeng; Liu, Minghua; Duan, Pengfei

    2018-05-29

    The orthogonal- or co-assembly of achiral perylene bisimide (PBI) with chiral gelators can be regulated by solvents. While the coassembly leads to the formation of chiroptical nanofibers through chirality transfer, the orthogonal assemblies could not. Moreover, protonation on the coassembled nanofibers could light up the circularly polarized luminescence (CPL).

  11. Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

    DEFF Research Database (Denmark)

    Damgaard, Ida; Bjerg, Poul Løgstrup; Bælum, Jacob

    2013-01-01

    subsampling of the clay till cores. The study demonstrates that an integrated approach combining chemical analysis, molecular microbial tools and compound specific isotope analysis (CSIA) was required in order to document biotic and abiotic degradations in the clay till system. © 2013 Elsevier B.V.......The degradation of chlorinated ethenes and ethanes in clay till was investigated at a contaminated site (Vadsby, Denmark) by high resolution sampling of intact cores combined with groundwater sampling. Over decades of contamination, bioactive zones with degradation of trichloroethene (TCE) and 1...

  12. Chiral charge erasure via thermal fluctuations of magnetic helicity

    International Nuclear Information System (INIS)

    Long, Andrew J.; Sabancilar, Eray

    2016-01-01

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ≳1/(αμ_5), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ_5 parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δ H∼λT and τ∼αλ"3T"2 for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t∼T"3/(α"5μ_5"4) until it reaches an equilibrium value H∼μ_5T"2/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ_5< T/α, this avenue for chiral charge erasure is found to be slower than the chiral magnetic effect for which t∼T/(α"3μ_5"2). This mechanism for chiral charge erasure can be important for the hypercharge sector of the Standard Model as well as extensions including U(1) gauge interactions, such as asymmetric dark matter models.

  13. Pure chiral optical fibres.

    Science.gov (United States)

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

    2011-01-17

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

  14. Relativistic Chiral Kinetic Theory

    International Nuclear Information System (INIS)

    Stephanov, Mikhail

    2016-01-01

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

  15. Relativistic Chiral Kinetic Theory

    Energy Technology Data Exchange (ETDEWEB)

    Stephanov, Mikhail

    2016-12-15

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

  16. Baryon Chiral Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Becher,

    2002-08-08

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

  17. Generalized chiral perturbation theory

    International Nuclear Information System (INIS)

    Knecht, M.; Stern, J.

    1994-01-01

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

  18. Generalized chiral membrane dynamics

    International Nuclear Information System (INIS)

    Cordero, R.; Rojas, E.

    2003-01-01

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

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

    International Nuclear Information System (INIS)

    Yu, Xiangying; Yao, Zhong-Ping

    2017-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-22

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

  1. Quenched chiral logarithms

    International Nuclear Information System (INIS)

    Sharpe, S.R.

    1992-04-01

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

  2. Solvent substitutes

    International Nuclear Information System (INIS)

    Evanoff, S.P.

    1995-01-01

    The environmental and industrial hygiene regulations promulgated since 1980, most notably the Superfund Amendments and Reauthorization Act (SARA), the Hazardous and Solid Waste Amendments to the Resources Conservation and Recovery Act (RCRA), and the Clean Air Act Amendments of 1990, have brought about an increased emphasis on user exposure, hazardous waste generation, and air emissions. As a result, industry is performing a fundamental reassessment of cleaning solvents, processes, and procedures. The more progressive organizations have made their goal the elimination of solvents that may pose significant potential human health and environmental hazards. This chapter discusses solvent cleaning in metal-finishing, metal-manufacturing, and industrial maintenance applications; precision cleaning; and electronics manufacturing. Nonmetallic cleaning, adhesives, coatings, inks, and aerosols also will be addressed, but in a more cursory manner

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

    KAUST Repository

    Zhu, Yihan

    2014-09-10

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

  4. Homochiral Evolution in Self-Assembled Chiral Polymers and Block Copolymers.

    Science.gov (United States)

    Wen, Tao; Wang, Hsiao-Fang; Li, Ming-Chia; Ho, Rong-Ming

    2017-04-18

    The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*). A helical (H*) phase to distinguish its P622 symmetry from that of normal hexagonally packed cylinder phase was discovered in the self-assembly of BCPs* due to the chirality effect on BCP self-assembly. Enantiomeric polylactide-containing BCPs*, polystyrene-b-poly(l-lactide) (PS-PLLA) and polystyrene-b-poly(d-lactide) (PS-PDLA), were synthesized for the examination of homochiral evolution. The optical activity (molecular chirality) of constituted chiral repeating unit in the chiral polylactide is detected by electronic circular dichroism (ECD) whereas the conformational chirality of helical polylactide chain can be explicitly determined by vibrational circular dichroism (VCD). The H* phases of the self-assembled polylactide-containing BCPs* can be directly visualized by 3D transmission electron microscopy (3D TEM) technique at which the handedness (hierarchical chirality) of the helical nanostructure is thus determined. The results from the ECD, VCD, and 3D TEM for the investigated chirality at different length scales suggest the homochiral evolution in the self-assembly of the BCPs*. For chiral polylactides, twisted lamellae in crystalline banded spherulite can be formed by dense packing scheme and effective interactions upon helical

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  6. Algebraic study of chiral anomalies

    Indian Academy of Sciences (India)

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

  7. Chiral anomalies and differential geometry

    International Nuclear Information System (INIS)

    Zumino, B.

    1983-10-01

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

  8. Solvent-extraction methods applied to the chemical analysis of uranium. III. Study of the extraction with inert solvents; Metodos de extraccion con disolventes aplicados al analisis quimico del uranio. III. Estudio de la extraccion con disolvente inertes

    Energy Technology Data Exchange (ETDEWEB)

    Vera Palomino, J; Palomares Delgado, F; Petrement Eguiluz, J C

    1964-07-01

    The extraction of uranium on the trace level is studied by using tributylphosphate as active agent under conditions aiming the attainment of quantitative extraction by means of a single step process using a number of salting-out agents and keeping inside the general lines as reported in two precedent papers. Two inert solvents were investigated, benzene and cyclohexane, which allowed to derive the corresponding empirical equations describing the extraction process and the results obtained were compared with those previously reported for solvents which, like ethyl acetate and methylisobuthylketone, favour to a more or less extend the extraction of uranium. (Author) 4 refs.

  9. Chiral phase transition in a covariant nonlocal NJL model

    International Nuclear Information System (INIS)

    General, I.; Scoccola, N.N.

    2001-01-01

    The properties of the chiral phase transition at finite temperature and chemical potential are investigated within a nonlocal covariant extension of the NJL model based on a separable quark-quark interaction. We find that for low values of T the chiral transition is always of first order and, for finite quark masses, at certain end point the transition turns into a smooth crossover. Our predictions for the position of this point is similar, although somewhat smaller, than previous estimates. (author)

  10. 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

  11. Transport properties of chiral fermions

    Energy Technology Data Exchange (ETDEWEB)

    Puhr, Matthias

    2017-04-26

    Anomalous transport phenomena have their origin in the chiral anomaly, the anomalous non-conservation of the axial charge, and can arise in systems with chiral fermions. The anomalous transport properties of free fermions are well understood, but little is known about possible corrections to the anomalous transport coefficients that can occur if the fermions are strongly interacting. The main goal of this thesis is to study anomalous transport effects in media with strongly interacting fermions. In particular, we investigate the Chiral Magnetic Effect (CME) in a Weyl Semimetal (WSM) and the Chiral Separation Effect (CSE) in finite-density Quantum Chromodynamics (QCD). The recently discovered WSMs are solid state crystals with low-energy excitations that behave like Weyl fermions. The inter-electron interaction in WSMs is typically very strong and non-perturbative calculations are needed to connect theory and experiment. To realistically model an interacting, parity-breaking WSM we use a tight-binding lattice Hamiltonian with Wilson-Dirac fermions. This model features a non-trivial phase diagram and has a phase (Aoki phase/axionic insulator phase) with spontaneously broken CP symmetry, corresponding to the phase with spontaneously broken chiral symmetry for interacting continuum Dirac fermions. We use a mean-field ansatz to study the CME in spatially modulated magnetic fields and find that it vanishes in the Aoki phase. Moreover, our calculations show that outside of the Aoki phase the electron interaction has only a minor influence on the CME. We observe no enhancement of the magnitude of the CME current. For our non-perturbative study of the CSE in QCD we use the framework of lattice QCD with overlap fermions. We work in the quenched approximation to avoid the sign problem that comes with introducing a finite chemical potential on the lattice. The overlap operator calls for the evaluation of the sign function of a matrix with a dimension proportional to the volume

  12. Alternative Bio-Based Solvents for Extraction of Fat and Oils: Solubility Prediction, Global Yield, Extraction Kinetics, Chemical Composition and Cost of Manufacturing

    Directory of Open Access Journals (Sweden)

    Anne-Gaëlle Sicaire

    2015-04-01

    Full Text Available The present study was designed to evaluate the performance of alternative bio-based solvents, more especially 2-methyltetrahydrofuran, obtained from crop’s byproducts for the substitution of petroleum solvents such as hexane in the extraction of fat and oils for food (edible oil and non-food (bio fuel applications. First a solvent selection as well as an evaluation of the performance was made with Hansen Solubility Parameters and the COnductor-like Screening MOdel for Realistic Solvation (COSMO-RS simulations. Experiments were performed on rapeseed oil extraction at laboratory and pilot plant scale for the determination of lipid yields, extraction kinetics, diffusion modeling, and complete lipid composition in term of fatty acids and micronutrients (sterols, tocopherols and tocotrienols. Finally, economic and energetic evaluations of the process were conducted to estimate the cost of manufacturing using 2-methyltetrahydrofuran (MeTHF as alternative solvent compared to hexane as petroleum solvent.

  13. Chiral perturbation theory

    International Nuclear Information System (INIS)

    Ecker, G.

    1996-06-01

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

  14. Asymmetric chiral colour

    International Nuclear Information System (INIS)

    Cuypers, F.

    1990-01-01

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

  15. Study of physico-chemical release of uranium and plutonium oxides during the combustion of polycarbonate and of ruthenium during the combustion of solvents used in the reprocessing of nuclear fuel

    International Nuclear Information System (INIS)

    Bouilloux, L.

    1998-01-01

    The level of consequences concerning a fire in a nuclear facility is in part estimated by the quantities and the physico-chemical forms of radioactive compounds that may be emitted out of the facility. It is therefore necessary to study the contaminant release from the fire. Because of the multiplicity of the scenarios, two research subjects were retained. The first one concerns the study of the uranium or plutonium oxides chemical release during the combustion of the polycarbonate glove box sides. The second one is about the physico chemical characterisation of the ruthenium release during the combustion of an organic solvent mixture (tributyl phosphate-dodecane) used for the nuclear fuel reprocessing. Concerning the two research subjects, the chemical release, i.e. means the generation of contaminant compounds gaseous in the fire, was modelled using thermodynamical simulations. Experiments were done in order to determine the ruthenium release factor during solvent combustion. A cone calorimeter was used for small scale experiments. These results were then validated by large scale tests under conditions close to the industrial process. Thermodynamical simulations, for the two scenarios studied. Furthermore, the experiments on solvent combustion allowed the determination of a suitable ruthenium release factor. Finally, the mechanism responsible of the ruthenium release has been found. (author)

  16. Chirality: from QCD to condensed matter

    International Nuclear Information System (INIS)

    Kharzeev, D.

    2015-01-01

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

  17. Chiral algebras for trinion theories

    International Nuclear Information System (INIS)

    Lemos, Madalena; Peelaers, Wolfger

    2015-01-01

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

  18. Chiral Organic Cages with a Triple-Stranded Helical Structure Derived from Helicene.

    Science.gov (United States)

    Malik, Abaid Ullah; Gan, Fuwei; Shen, Chengshuo; Yu, Na; Wang, Ruibin; Crassous, Jeanne; Shu, Mouhai; Qiu, Huibin

    2018-02-28

    We report the use of helicene with an intrinsic helical molecular structure to prepare covalent organic cages via imine condensation. The organic cages revealed a [3+2]-type architecture containing a triple-stranded helical structure with three helicene units arranged in a propeller-like fashion with the framework integrally twisted. Such structural chirality was retained upon dissolution in organic solvents, as indicated by a strong diastereotopy effect in proton NMR and unique Cotton effects in circular dichroism spectra. Further study on chiral adsorption showed that the chiral organic cages possess considerable enantioselectivity toward a series of aromatic racemates.

  19. Sustainable development of gree solvent separation process

    OpenAIRE

    Lisickov, Kiril; Fidancevska, Emilija; Grujic, Radoslav; Srebrenkoska, Vineta; Kuvendziev, Stefan

    2011-01-01

    Solvents defi ne a major part of the environmental performance of processes in the chemical industry and impact on cost, safety and health issues. The idea of green solvents expresses the goal to minimize the environmental impact resulting from the use of solvents in chemical production. In spite of conventional separation methods, precise process green technologies are based on the application of modern processes and process equipment as well as control and management...

  20. Chiral forces and molecular dissymmetry

    International Nuclear Information System (INIS)

    Mohan, R.

    1992-01-01

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

  1. Chirality in molecular collision dynamics

    Science.gov (United States)

    Lombardi, Andrea; Palazzetti, Federico

    2018-02-01

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

  2. Solvent-free thermoplastic-poly(dimethylsiloxane) bonding mediated by UV irradiation followed by gas-phase chemical deposition of an adhesion linker

    Science.gov (United States)

    Ahn, S. Y.; Lee, N. Y.

    2015-07-01

    Here, we introduce a solvent-free strategy for bonding various thermoplastic substrates with poly(dimethylsiloxane) (PDMS) using ultraviolet (UV) irradiation followed by the gas-phase chemical deposition of aminosilane on the UV-irradiated thermoplastic substrates. The thermoplastic substrates were first irradiated with UV for surface hydrophilic treatment and were then grafted with vacuum-evaporated aminosilane, where the alkoxysilane side reacted with the oxidized surface of the thermoplastic substrate. Next, the amine-terminated thermoplastic substrates were treated with corona discharge to oxidize the surface and were bonded with PDMS, which was also oxidized via corona discharge. The two substrates were then hermetically sealed and pressed under atmospheric pressure for 30 min at 60 °C. This process enabled the formation of a robust siloxane bond (Si-O-Si) between the thermoplastic substrate and PDMS under relatively mild conditions using an inexpensive and commercially available UV lamp and Tesla coil. Various thermoplastic substrates were examined for bonding with PDMS, including poly(methylmethacrylate) (PMMA), polycarbonate (PC), poly(ethyleneterephthalate) (PET) and polystyrene (PS). Surface characterizations were performed by measuring the contact angle and performing x-ray photoelectron spectroscopy analysis, and the bond strength was analyzed by conducting various mechanical force measurements such as pull, delamination, leak and burst tests. The average bond strengths for the PMMA-PDMS, PC-PDMS, PET-PDMS and PS-PDMS assemblies were measured at 823.6, 379.3, 291.2 and 229.0 kPa, respectively, confirming the highly reliable performance of the introduced bonding strategy.

  3. Chemical stability of two dentin single-bottle adhesives as a function of solvent loss = Estabilidade química de dois adesivos dentinários de frasco único em função da perda de solvente

    Directory of Open Access Journals (Sweden)

    Yévenes López, Ismael

    2008-01-01

    Full Text Available Objetivo: Dois sistemas adesivos de frasco único, Single-Bond e Prime and Bond NT, contendo etanol-água e acetona como solventes, respectivamente, foram avaliados quanto à sua estabilidade química devido à perda de solvente. Metodologia: A estabilidade foi medida pelas alterações de peso do adesivo em ensaios de degradação acelerada sob condições de temperatura e umidade acima das condições normais ao longo de 15 dias: 25±2ºC / 60±5% RH, 30±2ºC / 65±5% RH, 40±2ºC / 70±5% RH, e 50±2ºC / 75±5% RH. Para cada temperatura, a inclinação e a taxa constante de perda de peso foram registradas para obter o gráfico de Arrhenius. O conteúdo de água no adesivo Single Bond foi determinado por ensaio K Fisher e a quantidade total de solvente foi obtida pela diferença com o peso total. Resultados: Os resultados para Single Bond indicaram conteúdo de 5,90±0,08% de água e 39,14±1,19%de álcool. Para Prime and Bond NT a porcentagem de acetona foi de 43,08±1,15%. As alterações de peso depois dos ensaios de degradação acelerada mostraram que a perda de solvente no adesivo Single-Bond foi menor que no adesivo Prime and Bond NT. Conclusão: Os resultados sugerem que a estabilidade química do adesivo contendo etanolágua é maior que da formulação contendo acetona

  4. Can the chirality of the ISM be measured

    International Nuclear Information System (INIS)

    Pendleton, Y.; Sandford, S.A.; Werner, M.W.; Lauer, J.; Chang, S.

    1990-01-01

    Many moderately complex carbon-based molecules of the type associated with biological systems can exist in one of two mirror-image forms (left-handed and right-handed), which can be distinguished on the basis of their influence on the state of polarization of a light beam. Both forms are possible in nature; yet in living organisms it is invariably the rule that one of these two species predominates. This gives rise to a net chirality. One possible explanation for the net chirality is that the early earth was somehow seeded from the ISM with an excess of chiral organic compounds which led to the development of life forms which are based on left-handed amino acids and right-handed sugars. Molecular spectroscopy of the interstellar medium (ISM) has revealed a complex variety of molecular species similar to those thought to have been available in the oceans and atmospheres of the earth at the time life formed. The detection of such molecules demonstrates the generality of the chemical processes occurring in both environments. If this generality extends to the processes which produce chirality, it may be possible to detect a net chirality in the ISM. This is of particular interest because determining whether or not net chirality exists elsewhere in the universe is an essential aspect of understanding how life developed on earth and how widely distributed it might be. Researchers report preliminary results of a feasibility study to determine whether or not a net chirality in the ISM can be measured. If laboratory results identify candidate chiral molecules that might exist in the ISM, the next step in this feasibility study will be to estimate the detectability of the chiral signature in astrophysical environments

  5. Can the chirality of the ISM be measured

    Science.gov (United States)

    Pendleton, Y.; Sandford, S. A.; Werner, Michael W.; Lauer, J.; Chang, Sherwood

    1990-01-01

    Many moderately complex carbon-based molecules of the type associated with biological systems can exist in one of two mirror-image forms (left-handed and right-handed), which can be distinguished on the basis of their influence on the state of polarization of a light beam. Both forms are possible in nature; yet in living organisms it is invariably the rule that one of these two species predominates. This gives rise to a net chirality. One possible explanation for the net chirality is that the early earth was somehow seeded from the ISM with an excess of chiral organic compounds which led to the development of life forms which are based on left-handed amino acids and right-handed sugars. Molecular spectroscopy of the interstellar medium (ISM) has revealed a complex variety of molecular species similar to those thought to have been available in the oceans and atmospheres of the earth at the time life formed. The detection of such molecules demonstrates the generality of the chemical processes occurring in both environments. If this generality extends to the processes which produce chirality, it may be possible to detect a net chirality in the ISM. This is of particular interest because determining whether or not net chirality exists elsewhere in the universe is an essential aspect of understanding how life developed on earth and how widely distributed it might be. Researchers report preliminary results of a feasibility study to determine whether or not a net chirality in the ISM can be measured. If laboratory results identify candidate chiral molecules that might exist in the ISM, the next step in this feasibility study will be to estimate the detectability of the chiral signature in astrophysical environments.

  6. Acetone-based cellulose solvent.

    Science.gov (United States)

    Kostag, Marc; Liebert, Tim; Heinze, Thomas

    2014-08-01

    Acetone containing tetraalkylammonium chloride is found to be an efficient solvent for cellulose. The addition of an amount of 10 mol% (based on acetone) of well-soluble salt triethyloctylammonium chloride (Et3 OctN Cl) adjusts the solvent's properties (increases the polarity) to promote cellulose dissolution. Cellulose solutions in acetone/Et3 OctN Cl have the lowest viscosity reported for comparable aprotic solutions making it a promising system for shaping processes and homogeneous chemical modification of the biopolymer. Recovery of the polymer and recycling of the solvent components can be easily achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Computer Aided Solvent Selection and Design Framework

    DEFF Research Database (Denmark)

    Mitrofanov, Igor; Conte, Elisa; Abildskov, Jens

    and computer-aided tools and methods for property prediction and computer-aided molecular design (CAMD) principles. This framework is applicable for solvent selection and design in product design as well as process design. The first module of the framework is dedicated to the solvent selection and design...... in terms of: physical and chemical properties (solvent-pure properties); Environment, Health and Safety (EHS) characteristic (solvent-EHS properties); operational properties (solvent–solute properties). 3. Performing the search. The search step consists of two stages. The first is a generation and property...... identification of solvent candidates using special software ProCAMD and ProPred, which are the implementations of computer-aided molecular techniques. The second consists of assigning the RS-indices following the reaction–solvent and then consulting the known solvent database and identifying the set of solvents...

  8. Detecting the chirality for coupled quantum dots

    International Nuclear Information System (INIS)

    Cao Huijuan; Hu Lian

    2008-01-01

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

  9. Management of waste solvents in the chemical industry - An ecological comparison of distillation and incineration; Abfallloesungsmittelbewirtschaftung in der chemischen Industrie. Ein oekologischer Vergleich von Rektifikation und Verbrennung

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, T.B.

    2002-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a project in which two methods of dealing with solvent wastes were compared - distillation or incineration. The results of an analysis made of two case studies, a waste-solvent incineration plant and a batch distillation column, are presented. These were used to develop a simplified evaluation model for the two methods. The three methods used for the analysis of environmental impact are described - Eco-Indicator 99, ecological scarcity and primary energy demand. The authors note that the distillation model cannot be generally applied as the process is very dependent on the particular mixture of solvents being distilled and that the energy assessment method is dependent on the particular form of energy substituted by the energy produced in the incineration system. The evaluation model developed was used for 5 different mixtures of solvents. The results of the project show that apart from the availability of an accurate evaluation model, the life-cycle inventories for petrochemical production of solvents are limited and may compromise the applicability of the model to other mixtures of solvents.

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

    Science.gov (United States)

    Tong, Shengqiang

    2010-01-01

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

  11. Infrared absorption spectroscopy characterization of liquid-solid interfaces: The case of chiral modification of catalysts

    Science.gov (United States)

    Zaera, Francisco

    2018-03-01

    An overview is provided here of our work on the characterization of chiral modifiers for the bestowing of enantioselectivity to metal-based hydrogenation catalysts, with specific reference to the so-called Orito reaction. We start with a brief discussion of the use of infrared absorption spectroscopy (IR) for the characterization of chemical species at liquid-solid interfaces, describing the options available as well as the information that can be extracted from such experiments and the advantages and disadvantages associated with the technique. We then summarize the main results that we have reported to date from our IR study of the adsorption of cinchona alkaloids and related compounds from solutions onto platinum surfaces. Several observations are highlighted and placed in context in terms of the existing knowledge and their relevance to catalysis. Key conclusions include the uniqueness of the nature of the adsorbed species when in the presence of the solvent (versus when the uptake is done under vacuum, or versus the pure or dissolved molecules), the fact that each modifier adopts unique and distinct adsorption geometries on the surface and that those change with the concentration of the solution in ways that correlate well with the performance of the catalyst, the potential tendency of at least some of these chiral modifiers to bind to the surface primarily via the nitrogen atom of the amine group, not the aromatic ring as it is often assumed, and the observation that the ability of one modifier to dominate the catalytic chemistry in solutions containing mixtures of two or more of those is linked to their capacity for displacing each other from the surface, which in turn is determined by a balance between the strength of their binding to the surface and their solubility in the liquid solvent.

  12. CHIRAL CHEMISTRY OF PESTICIDES IN THE ENVIRONMENT WITH IMPLICATIONS FOR POLLUTION PREVENTION

    Science.gov (United States)

    Upwards of 25% of pesticides and other toxic pollutants are chiral; that is, they exist as two mirror image species called enantiomers. The enantiomers of a chiral compound have identical physical and abiotic chemical properties, but differ in biological properties such as microb...

  13. Modification of the rate of β-decay by chiral molecular environment

    International Nuclear Information System (INIS)

    Garay, A.S.; Biological Research Center, Szeged

    2000-01-01

    The radioactive isotope 32 P in the form of phosphoric acid (H 3 32 PO 4 ) and 22 Na in the form of sodium chloride ( 22 NaCl), were dissolved in R and S mirror image chiral solvents of 2-phenylbutyric acid (PBA) and diethyltartrate (DET). Then their decay rates were determined and compared to each other, to their decay rates in water and to their decay rates in racemic mixtures. It was found that 32 P decayed significantly faster if dissolved in R-PBA than in S-PBA. Similarly, 22 Na decayed significantly faster if dissolved in R-DET than in S-DET. Evidently the decay rates are sensitive to the right- and left-handed potential fields of the solvent molecules. However, the decay rate of 32 P was insensitive to the chiral senses of the DET solvents. Similarly, the decay rate of 22 Na was insensitive to the chiral senses of the PBA solvents. This can be tentatively explained by the interactions between the solvents and the solutes. It was also observed that in the first ten percent of the half-life time the decay of 32 P and particularly the decay of 22 Na often showed some deviation from the exponential behavior. This effect is chirality-dependent. (author)

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

    International Nuclear Information System (INIS)

    Sadzikowski, M.; Broniowski, W.

    2000-01-01

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

  15. Chiral magnetic effect of light

    Science.gov (United States)

    Hayata, Tomoya

    2018-05-01

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

  16. Comparative Analysis of Chemical Composition, Antioxidant Activity and Quantitative Characterization of Some Phenolic Compounds in Selected Herbs and Spices in Different Solvent Extraction Systems.

    Science.gov (United States)

    Sepahpour, Shabnam; Selamat, Jinap; Abdul Manap, Mohd Yazid; Khatib, Alfi; Abdull Razis, Ahmad Faizal

    2018-02-13

    This study evaluated the efficacy of various organic solvents (80% acetone, 80% ethanol, 80% methanol) and distilled water for extracting antioxidant phenolic compounds from turmeric, curry leaf, torch ginger and lemon grass extracts. They were analyzed regarding the total phenol and flavonoid contents, antioxidant activity and concentration of some phenolic compounds. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and the ferric reducing antioxidant power (FRAP) assay. Quantification of phenolic compounds was carried out using high-performance liquid chromatography (HPLC). All the extracts possessed antioxidant activity, however, the different solvents showed different efficiencies in the extraction of phenolic compounds. Turmeric showed the highest DPPH values (67.83-13.78%) and FRAP (84.9-2.3 mg quercetin/g freeze-dried crude extract), followed by curry leaf, torch ginger and lemon grass. While 80% acetone was shown to be the most efficient solvent for the extraction of total phenolic compounds from turmeric, torch ginger and lemon grass (221.68, 98.10 and 28.19 mg GA/g freeze dried crude extract, respectively), for the recovery of phenolic compounds from curry leaf (92.23 mg GA/g freeze-dried crude extract), 80% ethanol was the most appropriate solvent. Results of HPLC revealed that the amount of phenolic compounds varied depending on the types of solvents used.

  17. Comparative Analysis of Chemical Composition, Antioxidant Activity and Quantitative Characterization of Some Phenolic Compounds in Selected Herbs and Spices in Different Solvent Extraction Systems

    Directory of Open Access Journals (Sweden)

    Shabnam Sepahpour

    2018-02-01

    Full Text Available This study evaluated the efficacy of various organic solvents (80% acetone, 80% ethanol, 80% methanol and distilled water for extracting antioxidant phenolic compounds from turmeric, curry leaf, torch ginger and lemon grass extracts. They were analyzed regarding the total phenol and flavonoid contents, antioxidant activity and concentration of some phenolic compounds. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH free radical scavenging assay and the ferric reducing antioxidant power (FRAP assay. Quantification of phenolic compounds was carried out using high-performance liquid chromatography (HPLC. All the extracts possessed antioxidant activity, however, the different solvents showed different efficiencies in the extraction of phenolic compounds. Turmeric showed the highest DPPH values (67.83–13.78% and FRAP (84.9–2.3 mg quercetin/g freeze-dried crude extract, followed by curry leaf, torch ginger and lemon grass. While 80% acetone was shown to be the most efficient solvent for the extraction of total phenolic compounds from turmeric, torch ginger and lemon grass (221.68, 98.10 and 28.19 mg GA/g freeze dried crude extract, respectively, for the recovery of phenolic compounds from curry leaf (92.23 mg GA/g freeze-dried crude extract, 80% ethanol was the most appropriate solvent. Results of HPLC revealed that the amount of phenolic compounds varied depending on the types of solvents used.

  18. Chiral colour and axigluons

    International Nuclear Information System (INIS)

    Cuypers, F.

    1989-01-01

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

  19. Dense baryon matter with isospin and chiral imbalance in the framework of a NJL4 model at large Nc: Duality between chiral symmetry breaking and charged pion condensation

    Science.gov (United States)

    Khunjua, T. G.; Klimenko, K. G.; Zhokhov, R. N.

    2018-03-01

    In this paper the phase structure of dense quark matter has been investigated at zero temperature in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of massless (3 +1 )-dimensional Nambu-Jona-Lasinio model with two quark flavors. It has been shown that in the large-Nc limit (Nc is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter with isotopic asymmetry.

  20. Chiral Biomarkers in Meteorites

    Science.gov (United States)

    Hoover, Richard B.

    2010-01-01

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

  1. On chiral bosonization

    International Nuclear Information System (INIS)

    Bastianelli, F.

    1991-01-01

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

  2. Dynamical chiral bag model

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  3. Chiral Dynamics 2006

    Science.gov (United States)

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

    2007-10-01

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

  4. Identifying chiral bands in real nuclei

    International Nuclear Information System (INIS)

    Shirinda, O.; Lawrie, E.A.

    2012-01-01

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

  5. Heat Effect of the Protonation of Glycine and the Enthalpies of Resolvation of Participating Chemical Species in Water-Dimethylsulfoxide Solvent Mixtures

    Science.gov (United States)

    Isaeva, V. A.; Sharnin, V. A.

    2018-02-01

    Enthalpies of the protonation of glycine in water‒dimethylsulfoxide (DMSO) mixed solvents are determined calorimetrically in the range of DMSO mole fractions of 0.0 to 0.9, at T = 298.15 K and an ionic strength μ = 0.3 (NaClO4). It is established that the protonation of glycine becomes more exothermic with an increasing mole fraction of DMSO, and the enthalpies of resolvation of glycine and glycinium ions in water‒DMSO solvent mixtures are calculated. It is shown that the small changes in the enthalpy of protonation observed at low mole fractions of DMSO are caused by the contributions from the solvation of proton and protonated glycine cancelling each other out. The enthalpy term of the Gibbs energy of the reaction leading to the formation of glycinium ion is estimated along with the enthalpy of resolvation of the reacting species in the water‒DMSO mixed solvent.

  6. Chiral algebras of class S

    CERN Document Server

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

    2015-01-01

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

  7. Influence of different water-ethanol solvent systems on the spectroscopic and physico-chemical properties of the macrocyclic compounds pheophytin and chlorophyll a

    International Nuclear Information System (INIS)

    Moreira, Leonardo M.; Rodrigues, Maira R.; Oliveira, Hueder P. M. de; Lima, Adriana; Soares, Rafael R. S.; Batistela, Vagner R.; Gerola, Adriana P.; Hioka, Noboru; Severino, Divinomar; Baptista, Mauricio S.; Machado, Antonio Eduardo da Hora

    2010-01-01

    This work focus on the influence of solvent on the photophysical properties of chlorophyll a and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds. (author)

  8. Radiological assessment and chemical treatment of contaminated soil with naturally occurring radioactive materials ''NORM'' by leaching with different solvents and their reuse

    International Nuclear Information System (INIS)

    Nafae, T.M.

    2015-01-01

    Contaminated soil with naturally occurring radioactive material NORM is produced from uncontrolled disposal of oil field produced water in the surrounding environment or scale and sludge produced from clean-up operation system is considered as a real big problem in Iraq which causes exposure and contamination of worker and environment. The present work aims to treat the contaminated soil with NORM in order to minimize the volume of radioactive waste and to reduce the risk of radiation to the allowable limits. Samples of representative contaminated soil from Al-Rumaila oil field in Al-Basra governorate was prepared for analysis and leaching tests Gamma spectrometer with extended range low-level coaxial High Purity Germanium (HPGe) detector with high resolution (2.1 keV at 1332 keV) and 50% relative efficiency was utilized to measured all samples. Two techniques were tested, mechanical separation and chemical treatment. Screening of contaminated soil was performed to evaluate the feasibility of particle size separation. The fractions obtained varied between 75micro meter Greek Small Letter (200 mesh) to 300μm (48 mesh).The results show that the largest weight percent in fine particle size ( -75, -125+75, -250+125) μm is 73.9% and all radium isotopes are concentrated in 37.5μm particle size while small fluctuations are observed in the other particle size cuts.In the chemical treatment, many factors were studied to determine the best conditions for leaching process; type of solvent (HNO 3 , HCl, C 2 H 4 O 2 , H 2 SO 4 , NaOH, H 2 O), acid concentration (3, 5, 7, 10 M) , liquid to solid ratio(L:S) (3, 5, 7, 9, 18, 30 ml/g), temperature ( 28, 40, 60,78°C), and number of stages. Results indicate that only small portions of radium are present on the surface of soil particles, while most radium located within soil particles. Concentrated nitric acid (5M) was found to be the most effective solvent using two stages with L:S ratio of 9 ml/g at a temperature of 60 Co. At

  9. Solvent effects in chemistry

    CERN Document Server

    Buncel, Erwin

    2015-01-01

    This book introduces the concepts, theory and experimental knowledge concerning solvent effects on the rate and equilibrium of chemical reactions of all kinds.  It begins with basic thermodynamics and kinetics, building on this foundation to demonstrate how a more detailed understanding of these effects may be used to aid in determination of reaction mechanisms, and to aid in planning syntheses. Consideration is given to theoretical calculations (quantum chemistry, molecular dynamics, etc.), to statistical methods (chemometrics), and to modern day concerns such as ""green"" chemistry, where ut

  10. Simplified chiral superfield propagators for chiral constant mass superfields

    International Nuclear Information System (INIS)

    Srivastava, P.P.

    1983-01-01

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

  11. Hazardous solvent substitution

    International Nuclear Information System (INIS)

    Twitchell, K.E.

    1995-01-01

    Eliminating hazardous solvents is good for the environment, worker safety, and the bottom line. However, even though we are motivated to find replacements, the big question is 'What can we use as replacements for hazardous solvents?'You, too, can find replacements for your hazardous solvents. All you have to do is search for them. Search through the vendor literature of hundreds of companies with thousands of products. Ponder the associated material safety data sheets, assuming of course that you can obtain them and, having obtained them, that you can read them. You will want to search the trade magazines and other sources for product reviews. You will want to talk to users about how well the product actually works. You may also want to check US Environmental Protection Agency (EPA) and other government reports for toxicity and other safety information. And, of course, you will want to compare the product's constituent chemicals with the many hazardous constituency lists to ensure the safe and legal use of the product in your workplace

  12. Thin porphyrin composite membranes with enhanced organic solvent transport

    KAUST Repository

    Phuoc, Duong; Anjum, Dalaver H.; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira

    2018-01-01

    Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block

  13. Effects of polar protic solvents on dual emissions of 3 ...

    Indian Academy of Sciences (India)

    TECS

    Figure 1. Scheme of the ESIPT reaction of 3-hydroxy- chromone, 1. Chart 1. Chemical structures of the studied ... Materials and methods. Absorption and ... 85. Table 1. Spectroscopic properties of 3HC dyes in different polar solvents.a. Solvent.

  14. Chiral nanophotonics chiral optical properties of plasmonic systems

    CERN Document Server

    Schäferling, Martin

    2017-01-01

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

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

    Science.gov (United States)

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

    2018-05-11

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

  16. Calculation of 125Te NMR Chemical Shifts at the Full Four-Component Relativistic Level with Taking into Account Solvent and Vibrational Corrections: A Gateway to Better Agreement with Experiment.

    Science.gov (United States)

    Rusakova, Irina L; Rusakov, Yuriy Yu; Krivdin, Leonid B

    2017-06-29

    Four-component relativistic calculations of 125 Te NMR chemical shifts were performed in the series of 13 organotellurium compounds, potential precursors of the biologically active species, at the density functional theory level under the nonrelativistic and four-component fully relativistic conditions using locally dense basis set scheme derived from relativistic Dyall's basis sets. The relativistic effects in tellurium chemical shifts were found to be of as much as 20-25% of the total calculated values. The vibrational and solvent corrections to 125 Te NMR chemical shifts are about, accordingly, 6 and 8% of their total values. The PBE0 exchange-correlation functional turned out to give the best agreement of calculated tellurium shifts with their experimental values giving the mean absolute percentage error of 4% in the range of ∼1000 ppm, provided all corrections are taken into account.

  17. Lattice regularized chiral perturbation theory

    International Nuclear Information System (INIS)

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

    2004-01-01

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

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

    International Nuclear Information System (INIS)

    Laemmerhofer, M.

    1996-11-01

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

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

    Science.gov (United States)

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

    2017-08-15

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

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

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-08-01

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

  1. phenylalanine and l-tyrosine as chiral micellar media for the cat

    African Journals Online (AJOL)

    polar solvents [15-18]. Hence, surfactants offer the possibility for organic reactions to occur in aqueous media, and from the viewpoint of green chemistry, water is safer, harmless and environmentally benign [19]. However, there has been limited work on the use of chiral micellar media to catalyze Diels-. Alder reactions.

  2. Flatspace chiral supergravity

    Science.gov (United States)

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

    2018-05-01

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

  3. Chiral Nuclear Dynamics II

    CERN Document Server

    Rho, Mannque

    2008-01-01

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

  4. Chiral separation and enantioselective degradation of vinclozolin in soils.

    Science.gov (United States)

    Liu, Hui; Liu, Donghui; Shen, Zhigang; Sun, Mingjing; Zhou, Zhiqiang; Wang, Peng

    2014-03-01

    Vinclozolin is a chiral fungicide with potential environmental problems. The chiral separation of the enantiomers and enantioselective degradation in soil were investigated in this work. The enantiomers were separated by high-performance liquid chromatography (HPLC) on Chiralpak IA, IB, and AZ-H chiral columns under normal phase and the influence of the mobile phase composition on the separation was also studied. Complete resolutions were obtained on all three chiral columns under optimized conditions with the same elution order of (+)/(-). The residual analysis of the enantiomers in soil was conducted using accelerate solvent extraction followed by HPLC determination. The recoveries of the enantiomers ranged from 85.7-105.7% with relative standard deviation (SD) of 0.12-3.83%, and the limit of detection (LOD) of the method was 0.013 µg/g. The results showed that the degradations of vinclozolin enantiomers in the soils followed first-order kinetics. Preferential degradation of the (-)-enantiomer was observed only in one soil with the largest |ES| value of 0.047, and no obvious enantioselective degradation was observed in other soils. It was found that the persistence of vinclozolin in soil was related to pH values based on the half-lives. The two enantiomers disappeared about 8 times faster in basic soils than that in neutral or acidic soils. © 2014 Wiley Periodicals, Inc.

  5. Remediation of Contaminated Soils by Solvent Flushing

    NARCIS (Netherlands)

    Augustijn, Dionysius C.M.; Jessup, Ron E.; Rao, P. Suresh C.; Wood, A. Lynn

    1994-01-01

    Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, and increases the

  6. Chiral monolithic absorbent constructed by optically active helical-substituted polyacetylene and graphene oxide: preparation and chiral absorption capacity.

    Science.gov (United States)

    Li, Weifei; Wang, Bo; Yang, Wantai; Deng, Jianping

    2015-02-01

    Chiral monolithic absorbent is successfully constructed for the first time by using optically active helical-substituted polyacetylene and graphene oxide (GO). The preparative strategy is facile and straightforward, in which chiral-substituted acetylene monomer (Ma), cross-linker (Mb), and alkynylated GO (Mc) undergo copolymerization to form the desired monolithic absorbent in quantitative yield. The resulting monoliths are characterized by circular dichroism, UV-vis absorption, scanning electron microscopy (SEM), FT-IR, Raman, energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), XPS, and thermogravimetric analysis (TGA) techniques. The polymer chains derived from Ma form chiral helical structures and thus provide optical activity to the monoliths, while GO sheets contribute to the formation of porous structures. The porous structure enables the monolithic absorbents to demonstrate a large swelling ratio in organic solvents, and more remarkably, the helical polymer chains provide optical activity and further enantio-differentiating absorption ability. The present study establishes an efficient and versatile methodology for preparing novel functional materials, in particular monolithic chiral materials based on substituted polyacetylene and GO. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Nanoscale chirality in metal and semiconductor nanoparticles.

    Science.gov (United States)

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

    2016-10-18

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

  8. Chiral perturbation theory

    International Nuclear Information System (INIS)

    Harada, Masayasu

    2009-01-01

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

  9. Chiral quantum optics.

    Science.gov (United States)

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

    2017-01-25

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

  10. Amino acid chirality breaking by N-phosphorylation

    International Nuclear Information System (INIS)

    Zhao Yufen; Yan Qingjin.

    1995-01-01

    The chirality breaking of amino acid is a focus issue in the origin of life. For chemists, there are some interesting chemical approaches to solve the symmetry breaking problem. Our previous experiments indicated that when amino acids were phosphorylated, there were many bio-mimic reactions happened. In this paper, it was found that there had significant difference between the N-phosphoryl L- and D- amino acids such as serine and threonine. The optical rotation tracing experiments of the racemic N-phosphoamino acids also showed the similar results. The chirality breaking of amino acids by N-phosphorylation was a novel phenomena. (author). 3 refs, 1 fig. Abstract only

  11. Chiral-symmetry order parameter, the lattice, and nucleosynthesis

    International Nuclear Information System (INIS)

    McLerran, L.

    1987-01-01

    I discuss an order parameter for the chiral-symmetry restoration phase transition which may be useful in computations of big-bang nucleosynthesis, a phenomenon which requires a finite baryon-number density. This parameter is strictly speaking an order parameter in the large-N limit, and distinguishes between a parity-doubled and a massless-fermion realization of chiral-symmetry restoration. This order parameter may be evaluated at a zero net baryon-number density at finite temperature, and is useful as long as the baryon chemical potential μ is much less than the temperature T

  12. Chiral symmetry breaking in a semilocalized magnetic field

    Science.gov (United States)

    Cao, Gaoqing

    2018-03-01

    In this work, we explore the pattern of chiral symmetry breaking and restoration in a solvable magnetic field configuration within the Nambu-Jona-Lasinio model. The special semilocalized static magnetic field can roughly mimic the realistic situation in peripheral heavy ion collisions; thus, the study is important for the dynamical evolution of quark matter. We find that the magnetic-field-dependent contribution from discrete spectra usually dominates over the contribution from continuum spectra and chiral symmetry breaking is locally catalyzed by both the magnitude and scale of the magnetic field. The study is finally extended to the case with finite temperature or chemical potential.

  13. Chiral perturbation theory with nucleons

    International Nuclear Information System (INIS)

    Meissner, U.G.

    1991-09-01

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

  14. Chiral recognition in separation science: an overview.

    Science.gov (United States)

    Scriba, Gerhard K E

    2013-01-01

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

  15. NMR-based Enantiodifferentiation of Chiral trans-2-Phenylcyclopropane Derivatives Using a Chiral Lanthanide Shift Reagent

    International Nuclear Information System (INIS)

    Cho, Nam Sook; Kim, Hyun Sook; Song, Mi Sook

    2011-01-01

    In contrast with optical methods, there is no need to characterize the pure enantiomers. Instead, the NMR method makes use of chiral reagents that convert a mixture of enantiomers into a mixture of diastereomeric complexes. Integration of the resulting NMR spectra yields a direct measurement of enantiomeric purity as long as there is a sufficiently large difference between the chemical shifts of the two diastereoisomeric complexes to produce baseline-resolved peaks. Absolute enantiomeric configurations can also be determined using this method. Chiral lanthanide shift reagents have been used since the 1970s to form addition complexes with various compounds through interactions with electron donor sites. Lanthanide-induced, pseudo-contact shifts (LIS) are a function of the distance, r, between the nuclei under observation and the lanthanide center, and the angle, θ, between the line connecting the metal ion with the observed nucleus and the line representing the CLSR magnetic axis

  16. New remarks on chiral bosonization

    International Nuclear Information System (INIS)

    Souza Dutra, A. de

    1992-01-01

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

  17. Vector mesons and chiral symmetry

    International Nuclear Information System (INIS)

    Ecker, G.

    1989-01-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  19. Development and Investigation of NMR tools for chiral compound identification

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electronic, Optical and Nano Materials; Lansdon, Rick [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)

    2014-09-01

    The goal behind the assigned summer project was to investigate the ability of nuclear magnetic resonance spectroscopy (NMR) to identify enantiomers of select chiral organo-fluorophosphates (OFPs) compounds which are analogs of chemical warfare agents (CWAs, e.g. Sarin). This involved investigations utilizing chiral solvating agents (CSAs) and characterizing the binding phenomena with cyclodextrins. The resolution of OFPs enantiomers using NMR would be useful for research into toxicodynamics and toxicokinetics in biological systems due to the widely differing properties of the CWA enantiomers [1]. The optimization of decontamination abilities in the case of a CWA events, with this method’s potential rapidity and robustness, as well as the development of models correlating chiral compounds with CSAs for optimal resolution are all rational benefits of this research.

  20. Chiral reagents in glycosylation and modification of carbohydrates.

    Science.gov (United States)

    Wang, Hao-Yuan; Blaszczyk, Stephanie A; Xiao, Guozhi; Tang, Weiping

    2018-02-05

    Carbohydrates play a significant role in numerous biological events, and the chemical synthesis of carbohydrates is vital for further studies to understand their various biological functions. Due to the structural complexity of carbohydrates, the stereoselective formation of glycosidic linkages and the site-selective modification of hydroxyl groups are very challenging and at the same time extremely important. In recent years, the rapid development of chiral reagents including both chiral auxiliaries and chiral catalysts has significantly improved the stereoselectivity for glycosylation reactions and the site-selectivity for the modification of carbohydrates. These new tools will greatly facilitate the efficient synthesis of oligosaccharides, polysaccharides, and glycoconjugates. In this tutorial review, we will summarize these advances and highlight the most recent examples.

  1. Supernovae, Neutrinos and the Chirality of Amino Acids

    Directory of Open Access Journals (Sweden)

    Toshitaka Kajino

    2011-05-01

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

  2. Deformed chiral nucleons

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-04-18

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

  3. Amino Acids and Chirality

    Science.gov (United States)

    Cook, Jamie E.

    2012-01-01

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

  4. Host–Guest Chirality Interplay: A Mutually Induced Formation of a Chiral ZMOF and Its Double-Helix Polymer Guests

    KAUST Repository

    Luo, Xiaolong

    2016-01-12

    A novel homochiral zeolite-like metal-organic framework (ZMOF), [(Cu4I4) (dabco)2]·[Cu2(bbimb)]·3DMF (JLU-Liu23, dabco =1,4-diazabicyclo[2.2.2]-octane, H2bbimb =1,3-bis(2-benzimidazol)benzene, DMF = N,N-dimethylformamide), has been successfully constructed to host unprecedented DNA-like [Cu2(bbimb)]n polymers with double-helicity. The host-guest chirality interplay permitted the induced formation of an unusual gyroid MOF with homochirality and helical channels in the framework for the first time, JLU-Liu23. Importantly, the enantiomeric pairs (23P, 23M) can be promoted and isolated in the presence of appropriate chiral inducing agents, affording enantioselective separation of chiral molecules as well as small gas molecules. © 2016 American Chemical Society.

  5. Nanocellulose Derivative/Silica Hybrid Core-Shell Chiral Stationary Phase: Preparation and Enantioseparation Performance

    Directory of Open Access Journals (Sweden)

    Xiaoli Zhang

    2016-05-01

    Full Text Available Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material.

  6. Chiral fermions on the lattice

    International Nuclear Information System (INIS)

    Randjbar Daemi, S.; Strathdee, J.

    1995-01-01

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

  7. Switching of chirality by light

    NARCIS (Netherlands)

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

    1996-01-01

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

  8. Chiral dynamics with (nonstrange quarks

    Directory of Open Access Journals (Sweden)

    Kubis Bastian

    2017-01-01

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

  9. Chiral topological insulator of magnons

    Science.gov (United States)

    Li, Bo; Kovalev, Alexey A.

    2018-05-01

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

  10. Review of chiral perturbation theory

    Indian Academy of Sciences (India)

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

  11. Solvent extraction of zirconium

    International Nuclear Information System (INIS)

    Kim, S.S.; Yoon, J.H.

    1981-01-01

    The extraction of zirconium(VI) from an aqueous solution of constant ionic strength with versatic acid-10 dissolved in benzen was studied as a function of pH and the concentration of zirconium(VI) and organic acid. The effects of sulphate and chlorine ions on the extraction of the zirconium(VI) were briefly examined. It was revealed that (ZrOR 2 .2RH) is the predominant species of extracted zirconium(VI) in the versatic acid-10. The chemical equation and the apparent equilibrium constants thereof have been determined as follows. (ZrOsup(2+))aq+ 2(R 2 H 2 )sub(org) = (ZrOR 2 .2RH)sub(org)+2(H + )aq Ksub(Zr) = (ZrOR 2 .2RH)sub(org)(H + ) 2 /(ZrOsup(2+))sub(aq)(R 2 H 2 )sup(2)sub(org) = 3.3 x 10 -7 . The synergistic effects of TBP and D2EHPA were also studied. In the mixed solvent with 0.1M TBP, the synergistic effect was observed, while the mixed solvent with D2EHPA showed the antisynergistic effect. (Author)

  12. Poly(thieno[3,4–b]–1,4–oxathiane): Effect of solvent on the chemical synthesis and capacitance comparison in different electrolytes

    International Nuclear Information System (INIS)

    Wang, Zhipeng; Mo, Daize; Ma, Xiumei; Xu, Jingkun; Zhou, Weiqiang; Jiang, Qinglin; Feng, Zilan; Xiong, Jinhua; Zhu, Danhua; Zhou, Qianjie

    2015-01-01

    Graphical abstract: The electrochemical capacitance performance of PEOTT electrode from water was comparatively investigated using cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscope methods in the four solvent-electrolyte systems, i.e., H 2 O–H 2 SO 4 , H 2 O–HClO 4 , H 2 O–LiClO 4 , and ACN–LiClO 4 . The results revealed that the specific capacitance of PEOTT electrode was superior in acidic aqueous electrolytes than that in neutral pH aqueous or organic electrolyte. With these results, it is implied that PEOTT electrode employing HClO 4 aqueous electrolyte may be a promising electrode for supercapacitor applications. - Highlights: • A PEDOT sulfur analog was synthesized via chemical oxidation method firstly. • Effect of solvent on polymer structure was evaluated. • Effect of electrolyte on the capacitance performance was investigated. • PEOTT should be a promising supercapacitor material. - Abstract: Thieno[3,4-b]-1,4-oxathiane (EOTT), one asymmetrical analog of 3,4-ethylenedioxythiophene (EDOT), was synthesized and its chemical oxidative polymerization was carried out in different solvents (dichloromethane, water, and acetonitrile (CH 2 Cl 2 , H 2 O, and ACN)). The effect of the solvent on the structure, crystalline characteristic, morphology, and thermal stability of poly(thieno[3,4-b]-1,4-oxathiane) (PEOTT) were investigated by fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetry, respectively. PEOTT prepared from H 2 O exhibited higher electrical conductivity (∼10 0 S/cm) and more robust thermal stability. The electrochemical capacitance performance of PEOTT electrode in ACN–LiClO 4 was initially found dissatisfactory. Furthermore, the electrochemical properties of this electrode in another three aqueous electrolytes (H 2 SO 4 , HClO 4 , and LiClO 4 ) were also investigated comparatively by cyclic

  13. Analysis of metolachlor ethane sulfonic acid chirality in groundwater: A tool for dating groundwater movement in agricultural settings

    Science.gov (United States)

    Chemical chirality of pesticides can be a useful tool for studying environmental processes. The chiral forms of metolachlor ethane sulfonic acid (MESA), an abundant metabolite of metolachlor, and metolachlor were examined over a 6 year period in groundwater and a groundwater-fed stream in a riparia...

  14. Chirality-controlled crystallization via screw dislocations.

    Science.gov (United States)

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

    2018-04-11

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

  15. Chiral thermodynamics of nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Fiorilla, Salvatore

    2012-10-23

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

  16. Homogenization of resonant chiral metamaterials

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  17. Chiral thermodynamics of nuclear matter

    International Nuclear Information System (INIS)

    Fiorilla, Salvatore

    2012-01-01

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

  18. Determination of the absolute configurations at stereogenic centers in the presence of axial chirality.

    Science.gov (United States)

    Polavarapu, Prasad L; Jeirath, Neha; Kurtán, Tibor; Pescitelli, Gennaro; Krohn, Karsten

    2009-01-01

    Cephalochromin, a homodimeric naphthpyranone natural product, contains both axial chirality due to the hindered rotation along the biaryl axis and central chirality due to the C-2, C-2' stereogenic centers of the fused pyranone ring. For determining the absolute configurations (ACs) of central chirality elements, different chiroptical spectroscopic methods, namely vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotation (OR), have been used. From these experimental data, in conjunction with corresponding quantum chemical predictions at B3LYP/6-311G* level, it is found that the ECD spectra of cephalochromin are dominated by its axial chirality and are not suitable to distinguish the (aS,2S,2'S) and (aS,2R,2'R) diastereomers and hence to determine the ACs of the central chirality elements. OR signs also did not distinguish the (aS,2S,2'S) and (aS,2R,2'R) diastereomers. On other hand, VCD spectrum of cephalochromin exhibited separate spectral features attributable to axial chirality and stereogenic centers, thereby allowing the determination of both types of chirality elements. This is the first investigation demonstrating that, because of vibrations specific to the studied stereogenic centers, VCD spectroscopy can be used to simultaneously determine the ACs of axial and central chirality elements whenever other chiroptical methods (ECD and OR) fail to report on them. (c) 2009 Wiley-Liss, Inc.

  19. Macdonald index and chiral algebra

    Science.gov (United States)

    Song, Jaewon

    2017-08-01

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

  20. Comparison of Laboratory Experiments of Chemical, Biological, and Thermal Methods for Treatment of Chlorinated Solvent DNAPL at Kærgård Plantage in Denmark

    DEFF Research Database (Denmark)

    Christophersen, Mette; Christensen, Jørgen Fjeldsø; Jørgensen, Torben H.

    2010-01-01

    The Kærgård Plantage megasite on the western coast of Denmark represents one of the most difficult remediation challenges in Scandinavia. Disposal of an estimated 280,000 m3 of pharmaceutical wastes at the site from 1956 to 1973 resulted in the development of a complex mixture of contaminants...... in soil and groundwater, including sulfonamides, barbiturates, aniline, pyridine, chlorinated solvents (chloroethenes), fuel hydrocarbons, mercury, cyanide, lithium and many other compounds.  Wastes were disposed in six pits that continue to leach contaminants to groundwater. Contaminants in groundwater...... technologies for remediation of the residual wastes below the water table - first in the laboratory and then in pilot tests. Given the complex and highly concentrated mixture of contaminants, implementation of multiple or sequenced remediation technologies may be required to achieve cleanup goals.  An...

  1. Xe-129 NMR chemical shift in Xe@C-60 calculated at experimental conditions: Essential role of the relativity, dynamics, and explicit solvent

    Czech Academy of Sciences Publication Activity Database

    Standara, Stanislav; Kulhánek, P.; Marek, R.; Straka, Michal

    2013-01-01

    Roč. 34, č. 22 (2013), s. 1890-1898 ISSN 0192-8651 R&D Projects: GA ČR GA203/09/2037; GA ČR GA13-03978S Grant - others:7th European Community Framework Program(XE) FP7-286154; CEITEC-Central European Institute of Technology (European Regional Development)(XE) CZ.1.05/1.1.00/02.0068; Operational Program Research and Development for Innovations(XE) CZ.1.05/3.2.00/08.0144 Institutional support: RVO:61388963 Keywords : Xe-129 NMR * Xe@C-60 * dynamical averaging * explicit solvent * relativistic effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.601, year: 2013

  2. Chemical composition and antibacterial activity of Origanum saccatum P.H. Davis essential oil obtained by solvent-free microwave extraction: comparison with hydrodistillation.

    Science.gov (United States)

    Sozmen, Fazli; Uysal, Burcu; Oksal, Birsen S; Kose, Elif Odabas; Deniz, I Gokhan

    2011-01-01

    The components of the essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum saccatum P.H. Davis were identified by using GC/MS. The main constituents of both EOs obtained by SFME and HD, respectively, from O. saccatum were p-cymene (72.5 and 70.6%), thymol (9.32 and 8.11%), and carvacrol (7.18 and 6.36%). The EO obtained by SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than did the EO obtained by HD. The antibacterial activities of the EOs obtained by SFME and HD were evaluated with the disc diffusion method by comparison with 10 different bacterial strains. The antibacterial activity of the EO extracted by SFME was found to be more effective than that of the EO extracted by HD against seven of the tested bacteria.

  3. Solvents and solvent effects in organic chemistry

    National Research Council Canada - National Science Library

    Reichardt, C; Welton, T

    2011-01-01

    .../guest complexation equilibria and reactions in biphasic solvent systems and neoteric solvents, respectively. More than 900 new references have been added, giving preference to review articles, and many older ones have been deleted. New references either replace older ones or are added to the end of the respective reference list of each chapter. Th...

  4. Organic Solvent Tropical Report

    International Nuclear Information System (INIS)

    COWLEY, W.L.

    2000-01-01

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an unmitigated organic solvent fire is within risk evaluation guidelines

  5. Canyon solvent cleaning

    International Nuclear Information System (INIS)

    Reif, D.J.

    1986-01-01

    The HM Process at the Savannah River Plant (SRP) uses 7.5% tributylphosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, produce decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown the carbonate washing, although removing residual solvent activity does not remove binding ligands that hold fission products in the solvent. Treatment of solvent by an alumina adsorption process removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale alumina adsorption process and the use of the process to clean HM Process first cycle solvent are presented

  6. Solvent wash solution

    International Nuclear Information System (INIS)

    Neace, J.C.

    1986-01-01

    This patent describes a process for removing diluent degradation products from a solvent extraction solution comprising an admixture of an organic extractant for uranium and plutonium and a non-polar organic liquid diluent, which has been used to recover uranium and plutonium from spent nuclear fuel. Comprising combining a wash solution consisting of: (a) water; and (b) a positive amount up to about, an including, 50 volume percent of at least one highly-polar water-miscible organic solvent, based on the total volume of the water and the highly-polar organic solvent, with the solvent extraction solution after uranium and plutonium values have been stripped from the solvent extraction solution, the diluent degradation products dissolving in the highly-polar organic solvent and the extractant and diluent of the extraction solution not dissolving in the highly-polar organic solvent, and separating the highly-polar organic solvent and the extraction solution to obtain a purified extraction solution

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  8. Analysis of air-, moisture- and solvent-sensitive chemical compounds by mass spectrometry using an inert atmospheric pressure solids analysis probe.

    Science.gov (United States)

    Mosely, Jackie A; Stokes, Peter; Parker, David; Dyer, Philip W; Messinis, Antonis M

    2018-02-01

    A novel method has been developed that enables chemical compounds to be transferred from an inert atmosphere glove box and into the atmospheric pressure ion source of a mass spectrometer whilst retaining a controlled chemical environment. This innovative method is simple and cheap to implement on some commercially available mass spectrometers. We have termed this approach inert atmospheric pressure solids analysis probe ( iASAP) and demonstrate the benefit of this methodology for two air-/moisture-sensitive chemical compounds whose characterisation by mass spectrometry is now possible and easily achieved. The simplicity of the design means that moving between iASAP and standard ASAP is straightforward and quick, providing a highly flexible platform with rapid sample turnaround.

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

    Science.gov (United States)

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

    2008-05-16

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  11. Chiral PEPPSI Complexes: Synthesis, Characterization, and Application in Asymmetric Suzuki–Miyaura Coupling Reactions

    KAUST Repository

    Benhamou, Laure

    2014-01-13

    PEPPSI complexes incorporating chiral N-heterocyclic carbene (NHC) ligands based on 2,2-dimethyl-1-(o-substituted aryl)propan-1-amines were synthesized. Two complexes, with one saturated and one unsaturated NHC ligand, were structurally characterized. The chiral PEPPSI complexes were used in asymmetric Suzuki-Miyaura reactions, giving atropisomeric biaryl products in modest to good enantiomeric ratios. © 2013 American Chemical Society.

  12. Chiral PEPPSI Complexes: Synthesis, Characterization, and Application in Asymmetric Suzuki–Miyaura Coupling Reactions

    KAUST Repository

    Benhamou, Laure; Besnard, Cé line; Kü ndig, E. Peter

    2014-01-01

    PEPPSI complexes incorporating chiral N-heterocyclic carbene (NHC) ligands based on 2,2-dimethyl-1-(o-substituted aryl)propan-1-amines were synthesized. Two complexes, with one saturated and one unsaturated NHC ligand, were structurally characterized. The chiral PEPPSI complexes were used in asymmetric Suzuki-Miyaura reactions, giving atropisomeric biaryl products in modest to good enantiomeric ratios. © 2013 American Chemical Society.

  13. Chiral Thirring–Wess model

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  14. Chiral Thirring–Wess model

    International Nuclear Information System (INIS)

    Rahaman, Anisur

    2015-01-01

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

  15. Solvent distillations studies for a reprocessing plant

    International Nuclear Information System (INIS)

    Ginisty, C.; Guillaume, B.

    1989-01-01

    The substantial amounts of solvent used in large reprocessing plants are such that considerable care must be paid to solvent management to limit the production of organic wastes. The installation of intensive treatment by chemical regeneration serves to increase the service life of the solvent. General solvent management, combined with a distillation unit under reduced pressure also helps to recycle the two components of the solvent at a low activity level. Distillation also serves to remove the heavy degradation products that are generally responsible for poor hydraulic behavior and for the holdup of radioactive products such as plutonium, zirconium and ruthenium. From the safety standpoint, the flashpoint of the distilled diluent tends to rise. It can therefore be recycled without risk

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

    International Nuclear Information System (INIS)

    Kieu, T.D.

    1994-05-01

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

  17. Chirality: a relational geometric-physical property.

    Science.gov (United States)

    Gerlach, Hans

    2013-11-01

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

  18. Extreme chirality in Swiss roll metamaterials

    International Nuclear Information System (INIS)

    Demetriadou, A; Pendry, J B

    2009-01-01

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

  19. Preparative supercritical fluid chromatography: A powerful tool for chiral separations.

    Science.gov (United States)

    Speybrouck, David; Lipka, Emmanuelle

    2016-10-07

    In 2012, the 4 biggest pharmaceutical blockbusters were pure enantiomers and separating racemic mixtures is now frequently a key step in the development of a new drug. For a long time, preparative liquid chromatography was the technique of choice for the separation of chiral compounds either during the drug discovery process to get up to a hundred grams of a pure enantiomer or during the clinical trial phases needing kilograms of material. However the advent of supercritical Fluid Chromatography (SFC) in the 1990s has changed things. Indeed, the use of carbon dioxide as the mobile phase in SFC offers many advantages including high flow rate, short equilibration time as well as low solvent consumption. Despite some initial teething troubles, SFC is becoming the primary method for preparative chiral chromatography. This article will cover recent developments in preparative SFC for the separation of enantiomers, reviewing several aspects such as instrumentation, chiral stationary phases, mobile phases or purely preparative considerations including overloading, productivity or large scale chromatography. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pumsa-ard, K.

    2006-07-01

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

  1. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng [Irvine, CA; Sui, Guodong [Los Angeles, CA; Elizarov, Arkadij [Valley Village, CA; Kolb, Hartmuth C [Playa del Rey, CA; Huang, Jiang [San Jose, CA; Heath, James R [South Pasadena, CA; Phelps, Michael E [Los Angeles, CA; Quake, Stephen R [Stanford, CA; Tseng, Hsian-rong [Los Angeles, CA; Wyatt, Paul [Tipperary, IE; Daridon, Antoine [Mont-Sur-Rolle, CH

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  3. An overview of industrial solvent use or is there life after chlorinated solvents?

    International Nuclear Information System (INIS)

    Green, B.

    1991-01-01

    Everyone using industrial chemicals has been affected by the fire- storm of new regulations governing solvent use. How will companies currently using hazardous solvents prepare for the changes ahead? What will the impact be on commonly used industrial solvents? What effect are environmental pressures having on solvent use and disposal? Are the responsible individuals in your company up-to-date on phase-out schedules? This paper is written for an audience of compliance coordinators, consultants, production engineers and corporate management. In it, the either addresses the above questions and discusses the specific products affected. The author reviews currently available alternatives to chlorinated and hazardous solvents and introduces a simple system for rating alternatives. The program also includes a discussion of solvent minimization programs and worker reeducation

  4. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ehbert, D.

    1980-01-01

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

  5. Quenched Chiral Perturbation Theory to one loop

    NARCIS (Netherlands)

    Colangelo, G.; Pallante, E.

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

  6. Variational approach to chiral quark models

    Energy Technology Data Exchange (ETDEWEB)

    Futami, Yasuhiko; Odajima, Yasuhiko; Suzuki, Akira

    1987-03-01

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

  7. A variational approach to chiral quark models

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  8. Chirality plays important roles in radiopharmaceuticals

    International Nuclear Information System (INIS)

    Shen Yumei

    2006-01-01

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

  9. Pions and the chiral bag

    International Nuclear Information System (INIS)

    Rho, M.

    1982-01-01

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

  10. Fusion rules of chiral algebras

    International Nuclear Information System (INIS)

    Gaberdiel, M.

    1994-01-01

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

  11. Physics of chiral symmetry breaking

    International Nuclear Information System (INIS)

    Shuryak, E.V.

    1991-01-01

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

  12. Chirality and gravitational parity violation.

    Science.gov (United States)

    Bargueño, Pedro

    2015-06-01

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

  13. Chiral interaction and biomolecular evolution

    International Nuclear Information System (INIS)

    Gilat, G.

    1992-01-01

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

  14. Structure, solvent, and relativistic effects on the NMR chemical shifts in square-planar transition-metal complexes: assessment of DFT approaches

    Czech Academy of Sciences Publication Activity Database

    Vícha, J.; Novotný, J.; Straka, Michal; Repisky, M.; Ruud, K.; Komorovsky, S.; Marek, R.

    2015-01-01

    Roč. 17, č. 38 (2015), s. 24944-24955 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA14-03564S Institutional support: RVO:61388963 Keywords : NMR chemical shifts * transition metal complexes * relativistic effects * method calibration Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.449, year: 2015 http://pubs.rsc.org/en/content/articlepdf/2015/cp/c5cp04214c

  15. Solvent Handbook Database System user's manual

    International Nuclear Information System (INIS)

    1993-03-01

    Industrial solvents and cleaners are used in maintenance facilities to remove wax, grease, oil, carbon, machining fluids, solder fluxes, mold release, and various other contaminants from parts, and to prepare the surface of various metals. However, because of growing environmental and worker-safety concerns, government regulations have already excluded the use of some chemicals and have restricted the use of halogenated hydrocarbons because they affect the ozone layer and may cause cancer. The Solvent Handbook Database System lets you view information on solvents and cleaners, including test results on cleaning performance, air emissions, recycling and recovery, corrosion, and non-metals compatibility. Company and product safety information is also available

  16. Computer-Aided Solvent Screening for Biocatalysis

    DEFF Research Database (Denmark)

    Abildskov, Jens; Leeuwen, M.B. van; Boeriu, C.G.

    2013-01-01

    constrained properties related to chemical reaction equilibrium, substrate and product solubility, water solubility, boiling points, toxicity and others. Two examples are provided, covering the screening of solvents for lipase-catalyzed transesterification of octanol and inulin with vinyl laurate....... Esterification of acrylic acid with octanol is also addressed. Solvents are screened and candidates identified, confirming existing experimental results. Although the examples involve lipases, the method is quite general, so there seems to be no preclusion against application to other biocatalysts....

  17. Solvent management in a reprocessing plant

    International Nuclear Information System (INIS)

    Guillaume, B.; Germain, M.; Puyou, M.; Rouyer, H.

    1987-01-01

    Solvent management in large capacity reprocessing plant is studied to limit production of organic wastes. Chemical processing increases life time of solvent. Low pressure distillation allows the recycling of TBP and diluent at a low activity level. Besides heavy degradation products are eliminated. For the safety the flash point of distillated diluent increases slightly. Tests on an industrial scale started in 1985 and since more than 500 cubic meters were treated [fr

  18. Chiral soliton models for baryons

    International Nuclear Information System (INIS)

    Weigel, H.

    2008-01-01

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

  19. Surface defects and chiral algebras

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-26

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

  20. Asymmetric Synthesis via Chiral Aziridines

    DEFF Research Database (Denmark)

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

    1996-01-01

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

  1. Chiral symmetry on the lattice

    International Nuclear Information System (INIS)

    Creutz, M.

    1994-11-01

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

  2. Nonlinear responses of chiral fluids from kinetic theory

    Science.gov (United States)

    Hidaka, Yoshimasa; Pu, Shi; Yang, Di-Lun

    2018-01-01

    The second-order nonlinear responses of inviscid chiral fluids near local equilibrium are investigated by applying the chiral kinetic theory (CKT) incorporating side-jump effects. It is shown that the local equilibrium distribution function can be nontrivially introduced in a comoving frame with respect to the fluid velocity when the quantum corrections in collisions are involved. For the study of anomalous transport, contributions from both quantum corrections in anomalous hydrodynamic equations of motion and those from the CKT and Wigner functions are considered under the relaxation-time (RT) approximation, which result in anomalous charge Hall currents propagating along the cross product of the background electric field and the temperature (or chemical-potential) gradient and of the temperature and chemical-potential gradients. On the other hand, the nonlinear quantum correction on the charge density vanishes in the classical RT approximation, which in fact satisfies the matching condition given by the anomalous equation obtained from the CKT.

  3. Chiral-symmetry restoration in baryon-rich environments

    International Nuclear Information System (INIS)

    Kogut, J.; Matsuoka, H.; Stone, M.; Wyld, H.W.; Shenker, S.; Shigemitsu, J.; Sinclair, D.K.

    1983-04-01

    Chiral symmetry restoration in an environment rich in baryons is studied by computer simulation methods in SU(2) and SU(3) gauge theories in the quenched approximation. The basic theory of symmetry restoration as a function of chemical potential is illustrated and the implementation of the ideas on a lattice is made explicit. A simple mean field model is presented to guide one's expectations. The second order conjugate-gradient iterative method and the pseudo-fermion Monte Carlo procedure are convergent methods of calculating the fermion propagator in an environment rich in baryons. Computer simulations of SU(3) gauge theory show an abrupt chiral symmetry restoring transition and the critical chemical potential and induced baryon density are estimated crudely. A smoother transition is observed for the color group SU(2)

  4. Concentration-dependent multiple chirality transition in halogen-bond-driven 2D self-assembly process

    Science.gov (United States)

    Miao, Xinrui; Li, Jinxing; Zha, Bao; Miao, Kai; Dong, Meiqiu; Wu, Juntian; Deng, Wenli

    2018-03-01

    The concentration-dependent self-assembly of iodine substituted thienophenanthrene derivative (5,10-DITD) is investigated at the 1-octanic acid/graphite interface using scanning tunneling microscopy. Three kinds of chiral arrangement and transition of 2D molecular assembly mainly driven by halogen bonding is clearly revealed. At high concentration the molecules self-assembled into a honeycomb-like chiral network. Except for the interchain van der Waals forces, this pattern is stabilized by intermolecular continuous Cdbnd O⋯I⋯S halogen bonds in each zigzag line. At moderate concentration, a chiral kite-like nanoarchitecture are observed, in which the Cdbnd O⋯I⋯S and I⋯Odbnd C halogen bonds, along with the molecule-solvent Cdbnd O⋯I⋯H halogen bonds are the dominated forces to determine the structural formation. At low concentration, the molecules form a chiral cyclic network resulting from the solvent coadsorption mainly by molecule-molecule Cdbnd O⋯I⋯S halogen bonds and molecule-solvent Cdbnd O⋯I⋯H halogen bonds. The density of molecular packing becomes lower with the decreasing of the solution concentration. The solution-concentration dependent self-assembly of thienophenanthrene derivative with iodine and ester chain moieties reveals that the type of intermolecular halogen bond and the number of the co-adsorbing 1-octanic acids by molecule-solvent Cdbnd O⋯I⋯H halogen bonds determine the formation and transformation of chirality. This research emphasizes the role of different types of halogen (I) bonds in the controllable supramolecular structures and provides an approach for the fabrication of chirality.

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

    Directory of Open Access Journals (Sweden)

    Márcio S. Silva

    2017-02-01

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

  6. Reversible optical transcription of supramolecular chirality into molecular chirality

    NARCIS (Netherlands)

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

    2004-01-01

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

  7. Chiral current generation in QED by longitudinal photons

    Directory of Open Access Journals (Sweden)

    J.L. Acosta Avalo

    2016-08-01

    Full Text Available We report the generation of a pseudovector electric current having imbalanced chirality in an electron–positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered by a perturbative electric field parallel to B, associated to a pseudovector longitudinal mode propagating along B. An electromagnetic chemical potential was introduced, but our results remain valid even when it vanishes. A nonzero fermion mass was assumed, which is usually considered vanishing in the literature. In the quantum field theory formalism at finite temperature and density, an anomaly relation for the axial current was found for a medium of massive fermions. It bears some analogy to the Adler–Bell–Jackiw anomaly. From the expression for the chiral current in terms of the photon self-energy tensor in a medium, it is obtained that electrons and positrons scattered by longitudinal photons (inside the light cone contribute to the chiral current, as well as the to pair creation due to longitudinal photons (out of light cone. In the static limit, an electric pseudovector current is obtained in the lowest Landau level.

  8. Chiral current generation in QED by longitudinal photons

    Energy Technology Data Exchange (ETDEWEB)

    Acosta Avalo, J.L., E-mail: jlacosta@instec.cu [Instituto Superior de Tecnologías y Ciencias Aplicadas (INSTEC), Ave Salvador Allende, No. 1110, Vedado, La Habana 10400 (Cuba); Pérez Rojas, H., E-mail: hugo@icimaf.cu [Instituto de Cibernética, Matemática y Física (ICIMAF), Calle E esq 15, No. 309, Vedado, La Habana 10400 (Cuba)

    2016-08-15

    We report the generation of a pseudovector electric current having imbalanced chirality in an electron–positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered by a perturbative electric field parallel to B, associated to a pseudovector longitudinal mode propagating along B. An electromagnetic chemical potential was introduced, but our results remain valid even when it vanishes. A nonzero fermion mass was assumed, which is usually considered vanishing in the literature. In the quantum field theory formalism at finite temperature and density, an anomaly relation for the axial current was found for a medium of massive fermions. It bears some analogy to the Adler–Bell–Jackiw anomaly. From the expression for the chiral current in terms of the photon self-energy tensor in a medium, it is obtained that electrons and positrons scattered by longitudinal photons (inside the light cone) contribute to the chiral current, as well as the to pair creation due to longitudinal photons (out of light cone). In the static limit, an electric pseudovector current is obtained in the lowest Landau level.

  9. Oscillation damping of chiral string loops

    International Nuclear Information System (INIS)

    Babichev, Eugeny; Dokuchaev, Vyacheslav

    2002-01-01

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

  10. Chiral transformation: From single nanowire to double helix

    KAUST Repository

    Wang, Yong

    2011-12-21

    We report a new type of water-soluble ultrathin Au-Ag alloy nanowire (NW), which exhibits unprecedented behavior in a colloidal solution. Upon growth of a thin metal (Pd, Pt, or Au) layer, the NW winds around itself to give a metallic double helix. We propose that the winding originates from the chirality within the as-synthesized Au-Ag NWs, which were induced to untwist upon metal deposition. © 2011 American Chemical Society.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Molecular-level insights into chiral adsorption phenomena are highly relevant within the fields of asymmetric heterogeneous catalysis or chiral separation and may contribute to understand the origins of homochirality in nature. Here, we investigate chiral induction by the "sergeants and soldiers......" mechanism for an oligo(phenylene ethynylene) based chiral conformational switch by coadsorbing it with an intrinsically chiral seed on Au(111). Through statistical analysis of scanning tunneling microscopy (STM) data we demonstrate successful chiral induction with a very low concentration of seeding...... molecules down to 3%. The microscopic mechanism for the observed chiral induction is suggested to involve nucleation of the intrinsically chiral seeds, allowing for effective transfer and amplification of chirality to large numbers of soldier target molecules....

  12. Improved performance of nanowire–quantum-dot–polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials

    International Nuclear Information System (INIS)

    Nadarajah, A; Smith, T; Könenkamp, R

    2012-01-01

    We report a nanowire–quantum-dot–polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm −2 illumination. (paper)

  13. Chirality effect in disordered graphene ribbon junctions

    International Nuclear Information System (INIS)

    Long Wen

    2012-01-01

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

  14. No chiral truncation of quantum log gravity?

    Science.gov (United States)

    Andrade, Tomás; Marolf, Donald

    2010-03-01

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

  15. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  16. Theory of polyelectrolytes in solvents.

    Science.gov (United States)

    Chitanvis, Shirish M

    2003-12-01

    Using a continuum description, we account for fluctuations in the ionic solvent surrounding a Gaussian, charged chain and derive an effective short-ranged potential between the charges on the chain. This potential is repulsive at short separations and attractive at longer distances. The chemical potential can be derived from this potential. When the chemical potential is positive, it leads to a meltlike state. For a vanishingly low concentration of segments, this state exhibits scaling behavior for long chains. The Flory exponent characterizing the radius of gyration for long chains is calculated to be approximately 0.63, close to the classical value obtained for second order phase transitions. For short chains, the radius of gyration varies linearly with N, the chain length, and is sensitive to the parameters in the interaction potential. The linear dependence on the chain length N indicates a stiff behavior. The chemical potential associated with this interaction changes sign, when the screening length in the ionic solvent exceeds a critical value. This leads to condensation when the chemical potential is negative. In this state, it is shown using the mean-field approximation that spherical and toroidal condensed shapes can be obtained. The thickness of the toroidal polyelectrolyte is studied as a function of the parameters of the model, such as the ionic screening length. The predictions of this theory should be amenable to experimental verification.

  17. A New Twist on Chirality

    NARCIS (Netherlands)

    Feringa, Bernard

    2001-01-01

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

  18. Instantons and chiral symmetry breaking

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  19. Instantons and chiral symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-10-22

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

  20. Status of chiral perturbation theory

    International Nuclear Information System (INIS)

    Ecker, G.

    1996-10-01

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

  1. Principles of chiral perturbation theory

    International Nuclear Information System (INIS)

    Leutwyler, H.

    1995-01-01

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

  2. Chiral symmetry in perturbative QCD

    International Nuclear Information System (INIS)

    Trueman, T.L.

    1979-04-01

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

  3. Descendants of the Chiral Anomaly

    OpenAIRE

    Jackiw, R.

    2000-01-01

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

  4. Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

    Energy Technology Data Exchange (ETDEWEB)

    Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

    2016-10-01

    Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained beta-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer

  5. Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

    Science.gov (United States)

    Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

    2016-10-01

    Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained β-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer

  6. Chiral phase transition in the soft-wall model of AdS/QCD

    International Nuclear Information System (INIS)

    Chelabi, Kaddour; Fang, Zhen; Huang, Mei; Li, Danning; Wu, Yue-Liang

    2016-01-01

    We investigate the chiral phase transition in the soft-wall model of AdS/QCD at zero chemical potential for two-flavor and three-flavor cases, respectively. We show that there is no spontaneous chiral symmetry breaking in the original soft-wall model. After detailed analysis, we find that in order to realize chiral symmetry breaking and restoration, both profiles for the scalar potential and the dilaton field are essential. The scalar potential determines the possible solution structure of the chiral condensate, except the mass term, it takes another quartic term for the two-flavor case, and for the three-flavor case, one has to take into account an extra cubic term due to the t’Hooft determinant interaction. The profile of the dilaton field reflects the gluodynamics, which is negative at a certain ultraviolet scale and approaches positive quadratic behavior at far infrared region. With this set-up, the spontaneous chiral symmetry breaking in the vacuum and its restoration at finite temperature can be realized perfectly. In the two-flavor case, it gives a second order chiral phase transition in the chiral limit, while the transition turns to be a crossover for any finite quark mass. In the case of three-flavor, the phase transition becomes a first order one in the chiral limit, while above sufficient large quark mass it turns to be a crossover again. This scenario agrees exactly with the current understanding on chiral phase transition from lattice QCD and other effective model studies.

  7. Chiral Symmetry Breaking in Peptide Systems During Formation of Life on Earth

    Science.gov (United States)

    Konstantinov, Konstantin K.; Konstantinova, Alisa F.

    2018-03-01

    Chiral symmetry breaking in complex chemical systems with a large number of amino acids and a large number of similar reactions was considered. It was shown that effective averaging over similar reaction channels may result in very weak effective enantioselectivity of forward reactions, which does not allow most of the known models to result in chiral symmetry breaking during formation of life on Earth. Models with simple and catalytic synthesis of a single amino acid, formation of peptides up to length five, and sedimentation of insoluble pair of substances were considered. It was shown that depending on the model and the values of the parameters, chiral symmetry breaking may occur in up to about 10% out of all possible unique insoluble pair combinations even in the absence of any catalytic synthesis and that minimum total number of amino acids in the pair is 5. If weak enantioselective forward catalytic synthesis of amino acids is present, then the number of possible variants, in which chiral symmetry breaking may occur, increases substantially. It was shown that that the most interesting catalysts have zero or one amino acid of "incorrect" chirality. If the parameters of the model are adjusted in such a way to result in an increase of concentration of longer peptides, then catalysts with two amino acids of incorrect chirality start to appear at peptides of length five. Models of chiral symmetry breaking in the presence of epimerization were considered for peptides up to length three. It was shown that the range of parameters in which chiral symmetry breaking could occur significantly shrinks in comparison to previously considered models with peptides up to length two. An experiment of chiral symmetry breaking was proposed. The experiment consists of a three-step cycle: reversible catalytic synthesis of amino acids, reversible synthesis of peptides, and irreversible sedimentation of insoluble substances.

  8. Amplification of Chirality through Self-Replication of Micellar Aggregates in Water

    KAUST Repository

    Bukhriakov, Konstantin

    2015-03-17

    We describe a system in which the self-replication of micellar aggregates results in a spontaneous amplification of chirality in the reaction products. In this system, amphiphiles are synthesized from two "clickable" fragments: a water-soluble "head" and a hydrophobic "tail". Under biphasic conditions, the reaction is autocatalytic, as aggregates facilitate the transfer of hydrophobic molecules to the aqueous phase. When chiral, partially enantioenriched surfactant heads are used, a strong nonlinear induction of chirality in the reaction products is observed. Preseeding the reaction mixture with an amphiphile of one chirality results in the amplification of this product and therefore information transfer between generations of self-replicating aggregates. Because our amphiphiles are capable of catalysis, information transfer, and self-assembly into bounded structures, they present a plausible model for prenucleic acid "lipid world" entities. © 2015 American Chemical Society.

  9. Unusual dimeric tetrahydroxanthone derivatives from Aspergillus lentulus and the determination of their axial chiralities

    Science.gov (United States)

    Li, Tian-Xiao; Yang, Ming-Hua; Wang, Ying; Wang, Xiao-Bing; Luo, Jun; Luo, Jian-Guang; Kong, Ling-Yi

    2016-12-01

    The research on secondary metabolites of Aspergillus lentulus afforded eight unusual heterodimeric tetrahydroxanthone derivatives, lentulins A-H (2-9), along with the known compound neosartorin (1). Compounds 1-6 exhibited potent antimicrobial activities especially against methicillin-resistant Staphylococci. Their absolute configurations, particularly the axial chiralities, were unambiguously demonstrated by a combination of electronic circular dichroism (ECD), Rh2(OCOCF3)4-induced ECD experiments, modified Mosher methods, and chemical conversions. Interestingly, compounds 1-4 were the first samples of atropisomers within the dimeric tetrahydroxanthone class. Further investigation of the relationships between their axial chiralities and ECD Cotton effects led to the proposal of a specific CD Exciton Chirality rule to determine the axial chiralities in dimeric tetrahydroxanthones and their derivatives.

  10. Influence of Solvent-Solvent and Solute-Solvent Interaction Properties on Solvent-Mediated Potential

    International Nuclear Information System (INIS)

    Zhou Shiqi

    2005-01-01

    A recently proposed universal calculational recipe for solvent-mediated potential is applied to calculate excess potential of mean force between two large Lennard-Jones (LJ) or hard core attractive Yukawa particles immersed in small LJ solvent bath at supercritical state. Comparison between the present prediction with a hypernetted chain approximation adopted for solute-solute correlation at infinitely dilute limit and existing simulation data shows high accuracy for the region with large separation, and qualitative reliability for the solute particle contact region. The calculational simplicity of the present recipe allows for a detailed investigation on the effect of the solute-solvent and solvent-solvent interaction details on the excess potential of mean force. The resultant conclusion is that gathering of solvent particles near a solute particle leads to repulsive excess PMF, while depletion of solvent particles away from the solute particle leads to attractive excess PMF, and minor change of the solvent-solvent interaction range has large influence on the excess PMF.

  11. Nuclear chiral dynamics and thermodynamics

    Science.gov (United States)

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

    2013-11-01

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

  12. Chiral vortical effect from the compactified D4-branes with smeared D0-brane charge

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chao; Chen, Yidian [Institute of High Energy Physics, Chinese Academy of Sciences,Beijing 100049 (China); Huang, Mei [Institute of High Energy Physics, Chinese Academy of Sciences,Beijing 100049 (China); University of Chinese Academy of Sciences,Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,Beijing 100049 (China)

    2017-03-15

    By using the boundary derivative expansion formalism of fluid/gravity correspondence, we study the chiral vortical effect from the compactified D4-branes with smeared D0-brane charge. This background corresponds to a strongly coupled, nonconformal relativistic fluid with a conserved vector current. The presence of the chiral vortical effect is induced by the addition of a Chern-Simons term in the bulk action. Except that the non-dissipative anomalous viscous coefficient and the sound speed rely only on the chemical potential, most of the other thermal and hydrodynamical quantities of the first order depend both on the temperature and the chemical potential. According to our result, the way that the chiral vortical effect coefficient depends on the chemical potential seems irrelevant with whether the relativistic fluid is conformal or not. Stability analysis shows that this anomalous relativistic fluid is stable and the doping of the smeared D0-brane charge will slow down the sound speed.

  13. Timoshenko beam model for chiral materials

    Science.gov (United States)

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

    2018-06-01

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

  14. Hazardous solvent substitution

    International Nuclear Information System (INIS)

    Twitchell, K.E.

    1995-01-01

    This article is an overview of efforts at INEL to reduce the generation of hazardous wastes through the elimination of hazardous solvents. To aid in their efforts, a number of databases have been developed and will become a part of an Integrated Solvent Substitution Data System. This latter data system will be accessible through Internet

  15. Spin-Dependent Transport through Chiral Molecules Studied by Spin-Dependent Electrochemistry

    Science.gov (United States)

    2016-01-01

    Conspectus Molecular spintronics (spin + electronics), which aims to exploit both the spin degree of freedom and the electron charge in molecular devices, has recently received massive attention. Our recent experiments on molecular spintronics employ chiral molecules which have the unexpected property of acting as spin filters, by way of an effect we call “chiral-induced spin selectivity” (CISS). In this Account, we discuss new types of spin-dependent electrochemistry measurements and their use to probe the spin-dependent charge transport properties of nonmagnetic chiral conductive polymers and biomolecules, such as oligopeptides, L/D cysteine, cytochrome c, bacteriorhodopsin (bR), and oligopeptide-CdSe nanoparticles (NPs) hybrid structures. Spin-dependent electrochemical measurements were carried out by employing ferromagnetic electrodes modified with chiral molecules used as the working electrode. Redox probes were used either in solution or when directly attached to the ferromagnetic electrodes. During the electrochemical measurements, the ferromagnetic electrode was magnetized either with its magnetic moment pointing “UP” or “DOWN” using a permanent magnet (H = 0.5 T), placed underneath the chemically modified ferromagnetic electrodes. The spin polarization of the current was found to be in the range of 5–30%, even in the case of small chiral molecules. Chiral films of the l- and d-cysteine tethered with a redox-active dye, toludin blue O, show spin polarizarion that depends on the chirality. Because the nickel electrodes are susceptible to corrosion, we explored the effect of coating them with a thin gold overlayer. The effect of the gold layer on the spin polarization of the electrons ejected from the electrode was investigated. In addition, the role of the structure of the protein on the spin selective transport was also studied as a function of bias voltage and the effect of protein denaturation was revealed. In addition to

  16. Green and Bio-Based Solvents.

    Science.gov (United States)

    Calvo-Flores, Francisco G; Monteagudo-Arrebola, María José; Dobado, José A; Isac-García, Joaquín

    2018-04-24

    Chemical reactions and many of the procedures of separation and purification employed in industry, research or chemistry teaching utilize solvents massively. In the last decades, with the birth of Green Chemistry, concerns about the employment of solvents and the effects on human health, as well as its environmental impacts and its dependence on non-renewable raw materials for manufacturing most of them, has drawn the attention of the scientific community. In this work, we review the concept of green solvent and the properties and characteristics to be considered green. Additionally, we discuss the different possible routes to prepare many solvents from biomass, as an alternative way to those methods currently applied in the petrochemical industry.

  17. Inexpensive chirality on the lattice

    International Nuclear Information System (INIS)

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

    2000-01-01

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

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

    Chernodub, M.N.

    2016-01-01

    We show that a hot rotating fluid of relativistic chiral fermions possesses a new gapless collective mode associated with coherent propagation of energy density and chiral density waves along the axis of rotation. This mode, which we call the Chiral Heat Wave, emerges due to a mixed gauge-gravitational anomaly. At finite density the Chiral Heat Wave couples to the Chiral Vortical Wave while in the presence of an external magnetic field it mixes with the Chiral Magnetic Wave. The coupling of the Chiral Magnetic and Chiral Vortical Waves is also demonstrated. We find that the coupled waves — which are coherent fluctuations of the vector, axial and energy currents — have generally different velocities compared to the velocities of the individual waves.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2017-05-31

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

  2. QCD and the chiral critical point

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  3. Asymmetric synthesis using chiral-encoded metal

    Science.gov (United States)

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-08-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity.

  4. Nucleon parton distributions in chiral perturbation theory

    International Nuclear Information System (INIS)

    Moiseeva, Alena

    2013-01-01

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

  5. Quark mass correction to chiral separation effect and pseudoscalar condensate

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Er-dong [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190 (China); Kavli Institute of Theoretical Physics China, Chinese Academy of Sciences,Beijing 100190 (China); Lin, Shu [School of Physics and Astronomy, Sun Yat-Sen University,No 2 University Road, Zhuhai 519082 (China)

    2017-01-25

    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.

  6. Field theoretic perspectives of the Wigner function formulation of the chiral magnetic effect

    Science.gov (United States)

    Wu, Yan; Hou, De-fu; Ren, Hai-cang

    2017-11-01

    We assess the applicability of the Wigner function formulation in its present form to the chiral magnetic effect and note some issues regarding the conservation and the consistency of the electric current in the presence of an inhomogeneous and time-dependent axial chemical potential. The problems are rooted in the ultraviolet divergence of the underlying field theory associated with the axial anomaly and can be fixed with the Pauli-Villars regularization of the Wigner function. The chiral magnetic current with a nonconstant axial chemical potential is calculated with the regularized Wigner function and the phenomenological implications are discussed.

  7. Evaluation of the Process of Solvent Vapor Annealing on Organic Thin Films

    KAUST Repository

    Ren, Yi

    2011-01-01

    Solvent vapor annealing has recently emerged as an intriguing, room-temperature, and highly versatile alternative to thermal annealing. The chemically selective interaction between solvents and organic semiconductors opens new opportunities

  8. Bootstrapping N=2 chiral correlators

    Science.gov (United States)

    Lemos, Madalena; Liendo, Pedro

    2016-01-01

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

  9. Bootstrapping N=2 chiral correlators

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

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

  10. Bootstrapping N=2 chiral correlators

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-07

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

  11. MICROWAVE TECHNOLOGY CHEMICAL SYNTHESIS APPLICATIONS

    Science.gov (United States)

    Microwave-accelerated chemical syntheses in various solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although th...

  12. Chiral Tunnelling in Twisted Graphene Bilayer

    OpenAIRE

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

    2013-01-01

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

  13. Enantioselective Biotransformation of Chiral Persistent Organic Pollutants.

    Science.gov (United States)

    Zhang, Ying; Ye, Jing; Liu, Min

    2017-01-01

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

  14. Supersymmetry and the chiral Schwinger model

    International Nuclear Information System (INIS)

    Amorim, R.; Das, A.

    1998-01-01

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

  15. Probing chirality with a femtosecond reaction microscope

    Directory of Open Access Journals (Sweden)

    Janssen M. H. M.

    2013-03-01

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

  16. A spectral route to determining chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

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

  17. Higher derivative regularization and chiral anomaly

    International Nuclear Information System (INIS)

    Nagahama, Yoshinori.

    1985-02-01

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

  18. Chiral anomaly, bosonization and fractional charge

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  19. The chirality operators for Heisenberg spin systems

    International Nuclear Information System (INIS)

    Subrahmanyam, V.

    1994-01-01

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

  20. Chiral anomaly, bosonization, and fractional charge

    International Nuclear Information System (INIS)

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

    1985-01-01

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

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

    Science.gov (United States)

    Chen, Xingwu; Wang, Ling; Chen, Yinjie; Li, Chenyue; Hou, Guoyan; Liu, Xin; Zhang, Xiaoguang; He, Wanli; Yang, Huai

    2014-01-21

    A chiral nematic liquid crystal-photopolymerizable monomer-chiral azobenzene compound composite was prepared and then polymerized under UV irradiation. The reflection wavelength of the composite can be extended to cover the 1000-2400 nm range and also be adjusted to the visible light region by controlling the concentration of chiral compounds.

  2. Staggered chiral random matrix theory

    International Nuclear Information System (INIS)

    Osborn, James C.

    2011-01-01

    We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.

  3. Homogenization of resonant chiral metamaterials

    OpenAIRE

    Andryieuski, Andrei; Menzel, Christoph; Rockstuhl, Carsten; Malureanu, Radu; Lederer, Falk; Lavrinenko, Andrei

    2010-01-01

    Homogenization of metamaterials is a crucial issue as it allows to describe their optical response in terms of effective wave parameters as e.g. propagation constants. In this paper we consider the possible homogenization of chiral metamaterials. We show that for meta-atoms of a certain size a critical density exists above which increasing coupling between neighboring meta-atoms prevails a reasonable homogenization. On the contrary, a dilution in excess will induce features reminiscent to pho...

  4. Chiral Lagrangians and the SSC

    International Nuclear Information System (INIS)

    Dawson, S.

    1991-09-01

    In the event that the SSC does not observe any resonances such as a Higgs boson or a techni-rho meson, we would like to know if the SSC can still discover something about the nature of the electroweak symmetry breaking. We will use chiral Lagrangian techniques to address this question and analyze their utility for studying events containing W and Z gauge bosons at the SSC. 20 refs., 4 figs

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

    Science.gov (United States)

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

    2018-07-01

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

  6. Chiral 1,2- and 1,3-diol-functionalized chromophores as Lego building blocks for coupled structures.

    Science.gov (United States)

    Spange, Stefan; Hofmann, Katja; Walfort, Bernhard; Rüffer, Tobias; Lang, Heinrich

    2005-10-14

    Chiral nitroanilines containing 1,2- or 1,3-diol functionalities have been synthesized by nucleophilic aromatic substitution of fluoronitroanilines with 1-aminopropane-2,3-diols and 2-aminopropane-1,3-diol in the melt. X-ray structure analyses confirm retention of the configuration of the chiral center. The novel chromophores are suitable to link reversibly to various substituted arylboronic acids which allows the construction of new solvatochromic sensor molecules suitable to response to solvent and anion coordination by fluoride. The solvatochromism of the new compounds has been studied using the Kamlet-Taft LSE relationship.

  7. Is there chirality in atomic nuclei?

    International Nuclear Information System (INIS)

    Meng Jie

    2009-01-01

    Static chiral symmetries are common in nature, for example, the macroscopic spirals of snail shells, the microscopic handedness of certain molecules, and human hands. The concept of chirality in atomic nuclei was first proposed in 1997, and since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Recent theoretical and experimental progress in the verification of chirality in atomic nuclei will be reviewed, together with a discussion of the problems that await to be solved in the future. (authors)

  8. 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.

  9. Self-inductance of chiral conducting nanotubes

    International Nuclear Information System (INIS)

    Miyamoto, Yoshiyuki; Rubio, Angel; Louie, Steven G.; Cohen, Marvin L.

    1998-01-01

    Chiral conductivity in nanotubes has recently been predicted theoretically. The realization and application of chiral conducting nanotubes can be of great interest from both fundamental and technological viewpoints. These chiral currents, if they are realized, can be detected by measuring the self-inductance. We have treated Maxwell's equations for chiral conducting nanotubes (nanocoils) and find that the self-inductance and the resistivity of nanocoils should depend on the frequency of the alternating current even when the capacitance of the nanocoils is not taken into account. This is in contrast to elementary treatment of ordinary coils. This fact is useful to distinguish nanocoils by electrical measurements

  10. Frozen Chirality of Tertiary Aromatic Amides: Access to Enantioenriched Tertiary α-Amino Acid or Amino Alcohol without Chiral Reagent.

    Science.gov (United States)

    Mai, Thi Thoa; Viswambharan, Baby; Gori, Didier; Guillot, Régis; Naubron, Jean-Valère; Kouklovsky, Cyrille; Alezra, Valérie

    2017-04-27

    One of the fundamental and intriguing aspects of life is the homochirality of the essential molecules. In this field, the absolute asymmetric synthesis of α-amino acids is a major challenge. Herein, we report access, by chemical means, to tertiary α-amino acid derivatives in up to 96 % ee without using any chiral reagent. In our strategy, the dynamic axial chirality of tertiary aromatic amides is frozen in a crystal and is responsible for the stereoselectivity of the subsequent steps. Furthermore, we could control the configuration of the final product by manually sorting and selecting the initial crystals. Based on vibrational circular dichroism studies, we could rationalize the observed stereoselectivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Chiral four-membered cyclic nitrones; asymmetric induction in the (4+2)-cycloaddition reaction of chiral ynamines and nitroalkenes

    NARCIS (Netherlands)

    van Elburg, P.A.; Honig, G.W.N.; Reinhoudt, David

    1987-01-01

    Chiral four-membered cyclic nitrones were synthesized by the asymmetric (4+2)-cycloaddition of nitroalkenes 1 and chiral ynamines 2. The subsequent stereoselective addition of nucleophiles to these nitrones enabled the synthesis of chiral N-hydroxyazetidines.

  12. Two-chiral-component microemulsion electrokinetic chromatography-chiral surfactant and chiral oil: part 1. dibutyl tartrate.

    Science.gov (United States)

    Kahle, Kimberly A; Foley, Joe P

    2007-06-01

    The first simultaneous use of a chiral surfactant and a chiral oil for microemulsion EKC (MEEKC) is reported. Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2-hexanol (1.65% v/v), and dibutyl tartrate (D, L, or racemic, 1.23% v/v) were examined as chiral pseudostationary phases (PSPs) for the separation of six pairs of pharmaceutical enantiomers: pseudoephedrine, ephedrine, N-methyl ephedrine, metoprolol, synephrine, and atenolol. Subtle differences were observed for three chromatographic figures of merit (alpha(enant), alpha(meth), k) among the chiral microemulsions; a moderate difference was observed for efficiency (N) and elution range. Dual-chirality microemulsions provided both the largest and smallest enantioselectivities, due to small positive and negative synergies between the chiral microemulsion components. For the ephedrine family of compounds, dual-chiral microemulsions with surfactant and oil in opposite stereochemical configurations provided higher enantioselectivities than the single-chiral component microemulsion (RXX), whereas dual-chiral microemulsions with surfactant and oil in the same stereochemical configurations provided lower enantioselectivities than RXX. Slight to moderate enantioselective synergies were confirmed using a thermodynamic model. Efficiencies observed with microemulsions comprised of racemic dibutyl tartrate or dibutyl-D-tartrate were significantly higher than those obtained with dibutyl-L-tartrate, with an average difference in plate count of about 25 000. Finally, one two-chiral-component microemulsion (RXS) provided significantly better resolution than the remaining one- and two-chiral-component microemulsions for the ephedrine-based compounds, but only slightly better or equivalent resolution for non-ephedrine compounds.

  13. Isotope effects in ion-exchange equilibria in aqueous and mixed solvent systems

    International Nuclear Information System (INIS)

    Gupta, A.R.

    1979-01-01

    Isotope effects in ion-exchange equilibria in aqueous and mixed solvents are analyzed in terms of the general features of ion-exchange equilibria and of isotope effects in chemical equilibria. The special role of solvent fractionation effects in ion-exchange equilibria in mixed solvents is pointed out. The various situations arising in isotope fractionation in ion exchange in mixed solvents due to solvent fractionation effects are theoretically discussed. The experimental data on lithium isotope effects in ion-exchange equilibria in mixed solvents are shown to conform to the above situations. The limitations of ion-exchange equilibria in mixed solvents for isotope fractionation are pointed out. 3 tables

  14. Chiral ferrocenes in asymmetric catalysis: synthesis and applications

    National Research Council Canada - National Science Library

    Dai, Li-Xin; Hou, Xue-Long

    2010-01-01

    .... It provides a thorough overview of the synthesis and characterization of different types of chiral ferrocene ligands, their application to various catalytic asymmetric reactions, and versatile chiral...

  15. Solvent-tolerant bacteria in biocatalysis.

    NARCIS (Netherlands)

    Bont, de J.A.M.

    1998-01-01

    The toxicity of fine chemicals to the producer organism is a problem in several biotechnological production processes. In several instances, an organic phase can be used to extract the toxic product from the aqueous phase during a fermentation. With the discovery of solvent-tolerant bacteria, more

  16. SHORT COMMUNICATION SOLVENT FREE PREPARATION OF N ...

    African Journals Online (AJOL)

    Preferred Customer

    KEYWORDS: Solvent free, Maleanilic acids, Maleic anhydride, Aniline derivatives ... associated with the carboxylic group between 3275-2877 cm-1, the weak –NH .... Chemical shifts (σ/ppm) relative to TMS*. O-H N-H Ha. Hb. Hc. Hd. He. Hf.

  17. Advanced integrated solvent extraction systems

    Energy Technology Data Exchange (ETDEWEB)

    Horwitz, E.P.; Dietz, M.L.; Leonard, R.A. [Argonne National Lab., IL (United States)

    1997-10-01

    Advanced integrated solvent extraction systems are a series of novel solvent extraction (SX) processes that will remove and recover all of the major radioisotopes from acidic-dissolved sludge or other acidic high-level wastes. The major focus of this effort during the last 2 years has been the development of a combined cesium-strontium extraction/recovery process, the Combined CSEX-SREX Process. The Combined CSEX-SREX Process relies on a mixture of a strontium-selective macrocyclic polyether and a novel cesium-selective extractant based on dibenzo 18-crown-6. The process offers several potential advantages over possible alternatives in a chemical processing scheme for high-level waste treatment. First, if the process is applied as the first step in chemical pretreatment, the radiation level for all subsequent processing steps (e.g., transuranic extraction/recovery, or TRUEX) will be significantly reduced. Thus, less costly shielding would be required. The second advantage of the Combined CSEX-SREX Process is that the recovered Cs-Sr fraction is non-transuranic, and therefore will decay to low-level waste after only a few hundred years. Finally, combining individual processes into a single process will reduce the amount of equipment required to pretreat the waste and therefore reduce the size and cost of the waste processing facility. In an ongoing collaboration with Lockheed Martin Idaho Technology Company (LMITCO), the authors have successfully tested various segments of the Advanced Integrated Solvent Extraction Systems. Eichrom Industries, Inc. (Darien, IL) synthesizes and markets the Sr extractant and can supply the Cs extractant on a limited basis. Plans are under way to perform a test of the Combined CSEX-SREX Process with real waste at LMITCO in the near future.

  18. Physiology of solvent tolerance in Pseudomonas putida S12

    NARCIS (Netherlands)

    Isken, S.

    2000-01-01

    Hydrophobic organic solvents, like toluene, are toxic for living organisms. This toxicity is an important drawback in the environmental biotechnology as well as in the application of solvents in the production of fine chemicals by whole-cell biotransformations. The effects of organic

  19. Challenges in subsurface in situ remediation of chlorinated solvents

    DEFF Research Database (Denmark)

    Broholm, Mette Martina; Fjordbøge, Annika Sidelmann; Christiansen, Camilla Maymann

    2014-01-01

    Chlorinated solvent source zones in the subsurface pose a continuous threat to groundwater quality at many sites worldwide. In situ remediation of these sites is particularly challenging in heterogeneous fractured media and where the solvents are present as DNAPL. In situ remediation by chemical...

  20. Solvent - solute interaction

    International Nuclear Information System (INIS)

    Urbanczyk, A.; Kalinowski, M.K.

    1983-01-01

    The electronic absorption spectrum of vanadyl acetylacetonate has been studied in 15 organic solvents. It has been found that wavenumbers and molar absorptivities of the long-wavelength bands (d-d transitions) can be well described by a complementary Lewis acid-base model including Gutmann's donor number [Gutmann V., Wychera E., Inorg. Nucl. Chem. Letters 2, 257 (1966)] and acceptor number [Mayer U., Gutmann V., Gerger W., Monatsh. Chem. 106, 1235 (1975)] of a solvent. This model describes also the solvent effect of the hyperfine splitting constant, Asub(iso)( 51 V), from e.s.r. spectra of VOacac 2 . These observations are discussed in terms of the donor-acceptor concept for solvent-solute interactions. (Author)

  1. Chiral ligand-protected gold nanoclusters: Considering the optical activity from a viewpoint of ligand dissymmetric field

    Directory of Open Access Journals (Sweden)

    Hiroshi Yao

    2016-10-01

    Full Text Available Chirality is a geometric property of a physical, chemical, or biological object, which is not superimposable on its mirror image. Its significant presence has led to a strong demand in the development of chiral drugs, sensors, catalysts, and photofunctional materials. In recent years, chirality of nanoscale organic/inorganic hybrids has received tremendous attention owing to potential applications in chiral nanotechnology. In particular, with the recent progress in the syntheses and characterizations of atomically precise gold nanoclusters protected by achiral thiolates, atomic level origins of their chirality have been unveiled. On the other hand, chirality or optical activity in metal nanoclusters can also be introduced via the surface chiral ligands, which should be universal for the nanosystems. This tutorial review presents some optically-active metal (gold nanoclusters protected by chiral thiolates or phosphines, and their chiroptical (or circular dichroism; CD properties are discussed mostly from a viewpoint of the ligand dissymmetric field scheme. The examples are the gold nanoclusters protected by (R-/(S-2-phenylpropane-1-thiol, (R-/(S-mercaptosuccinic acid, phenylboronate-D/L-fructose complexes, phosphine sulfonate-ephedrinium ion pairs, or glutathione. Some methodologies for versatile asymmetric transformation and chiroptical controls of the nanocluster compounds are also described. In the dissymmetric field model as the origin of optical activity, the chiroptical responses of the gold nanoclusters are strongly associated with coupled oscillator and/or CD stealing mechanisms based on the concept of induced CD (ICD derived from a perturbation theory, so on this basis, some characteristic features of the observed CD responses of chiral ligand-protected gold nanoclusters are presented in detail. We believe that various kinds of origins of chirality found in ligand-protected gold nanoclusters may provide models for understanding those of

  2. Next Generation Solvent Performance in the Modular Caustic Side Solvent Extraction Process - 15495

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Tara E. [Savannah River Remediation, LLC., Aiken, SC (United States); Scherman, Carl [Savannah River Remediation, LLC., Aiken, SC (United States); Martin, David [Savannah River Remediation, LLC., Aiken, SC (United States); Suggs, Patricia [Savannah River Site (SRS), Aiken, SC (United States)

    2015-01-14

    Changes to the Modular Caustic Side Solvent Extraction Unit (MCU) flow-sheet were implemented in the facility. Implementation included changing the scrub and strip chemicals and concentrations, modifying the O/A ratios for the strip, scrub, and extraction contactor banks, and blending the current BoBCalixC6 extractant-based solvent in MCU with clean MaxCalix extractant-based solvent. During the successful demonstration period, the MCU process was subject to rigorous oversight to ensure hydraulic stability and chemical/radionuclide analysis of the key process tanks (caustic wash tank, solvent hold tank, strip effluent hold tank, and decontaminated salt solution hold tank) to evaluate solvent carryover to downstream facilities and the effectiveness of cesium removal from the liquid salt waste. Results indicated the extraction of cesium was significantly more effective with an average Decontamination Factor (DF) of 1,129 (range was 107 to 1,824) and that stripping was effective. The contactor hydraulic performance was stable and satisfactory, as indicated by contactor vibration, contactor rotational speed, and flow stability; all of which remained at or near target values. Furthermore, the Solvent Hold Tank (SHT) level and specific gravity was as expected, indicating that solvent integrity and organic hydraulic stability were maintained. The coalescer performances were in the range of processing results under the BOBCalixC6 flow sheet, indicating negligible adverse impact of NGS deployment. After the Demonstration period, MCU began processing via routine operations. Results to date reiterate the enhanced cesium extraction and stripping capability of the Next Generation Solvent (NGS) flow sheet. This paper presents process performance results of the NGS Demonstration and continued operations of MCU utilizing the blended BobCalixC6-MaxCalix solvent under the NGS flowsheet.

  3. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Ebert, D.; Volkov, M.K.

    1981-01-01

    The pion polarizability is calculated in a chiral meson-quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Llanta and Tarrach is given. (orig.)

  4. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ehbert, D.

    1981-01-01

    The pion polarizability is calculated in a chiral meson- quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Llanta and Tarrach is given [ru

  5. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ebert, D.

    1981-01-01

    It is shown that the pion polarizability calculated in a chiral model with quark loops agrees exactly with the analogous quantity found in a chiral meson-baryon model. The results of a paper by Llanta and Tarrach are discussed critically

  6. Massive states in chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

    1995-08-01

    It is shown that the chiral nonanalytic terms generated by {Delta}{sub 33} resonance in the nucleon self-energy is reproduced in chiral perturbation theory by perturbing appropriate local operators contained in the pion-nucleon effective Lagrangian itself. (orig.)

  7. LINEARLY POLARIZED PROBES OF SURFACE CHIRALITY

    NARCIS (Netherlands)

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

    1995-01-01

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

  8. Pentaquarks in chiral color dielectric model

    Indian Academy of Sciences (India)

    Recent experiments indicate that a narrow baryonic state having strangeness +1 and mass of about 1540 MeV may be existing. Such a state was predicted in chiral model by Diakonov et al. In this work I compute the mass and width of this state in chiral color dielectric model. I show that the computed width is about 30 MeV.

  9. Orientation-Dependent Handedness and Chiral Design

    Directory of Open Access Journals (Sweden)

    Efi Efrati

    2014-01-01

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

  10. Chiral gravity, log gravity, and extremal CFT

    International Nuclear Information System (INIS)

    Maloney, Alexander; Song Wei; Strominger, Andrew

    2010-01-01

    We show that the linearization of all exact solutions of classical chiral gravity around the AdS 3 vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

  11. Chirality in nonlinear optics and optical switching

    NARCIS (Netherlands)

    Meijer, E.W.; Feringa, B.L.

    1993-01-01

    Chirality in molecular opto-electronics is limited sofar to the use of optically active liquid crystals and a number of optical phenomena are related to the helical macroscopic structure obtained by using one enantiomer, only. In this paper, the use of chirality in nonlinear optics and optical

  12. On infinite regular and chiral maps

    OpenAIRE

    Arredondo, John A.; Valdez, Camilo Ramírez y Ferrán

    2015-01-01

    We prove that infinite regular and chiral maps take place on surfaces with at most one end. Moreover, we prove that an infinite regular or chiral map on an orientable surface with genus can only be realized on the Loch Ness monster, that is, the topological surface of infinite genus with one end.

  13. Chiral bosonization on a Riemann surface

    International Nuclear Information System (INIS)

    Eguchi, Tohru; Ooguri, Hirosi

    1987-01-01

    We point out that the basic addition theorem of θ-functions, Fay's identity, implies an equivalence between bosons and chiral fermions on Riemann surfaces with arbitrary genus. We present a rule for a bosonized calculation of correlation functions. We also discuss ghost systems of n and (1-n) tensors and derive formulas for their chiral determinants. (orig.)

  14. Dual chiral density wave in quark matter

    International Nuclear Information System (INIS)

    Tatsumi, Toshitaka

    2002-01-01

    We prove that quark matter is unstable for forming a dual chiral density wave above a critical density, within the Nambu-Jona-Lasinio model. Presence of a dual chiral density wave leads to a uniform ferromagnetism in quark matter. A similarity with the spin density wave theory in electron gas and the pion condensation theory is also pointed out. (author)

  15. DEVELOPMENT AND REGISTRATION OF CHIRAL DRUGS

    NARCIS (Netherlands)

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

    1993-01-01

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

  16. Chiralities of spiral waves and their transitions.

    Science.gov (United States)

    Pan, Jun-ting; Cai, Mei-chun; Li, Bing-wei; Zhang, Hong

    2013-06-01

    The chiralities of spiral waves usually refer to their rotation directions (the turning orientations of the spiral temporal movements as time elapses) and their curl directions (the winding orientations of the spiral spatial geometrical structures themselves). Traditionally, they are the same as each other. Namely, they are both clockwise or both counterclockwise. Moreover, the chiralities are determined by the topological charges of spiral waves, and thus they are conserved quantities. After the inwardly propagating spirals were experimentally observed, the relationship between the chiralities and the one between the chiralities and the topological charges are no longer preserved. The chiralities thus become more complex than ever before. As a result, there is now a desire to further study them. In this paper, the chiralities and their transition properties for all kinds of spiral waves are systemically studied in the framework of the complex Ginzburg-Landau equation, and the general relationships both between the chiralities and between the chiralities and the topological charges are obtained. The investigation of some other models, such as the FitzHugh-Nagumo model, the nonuniform Oregonator model, the modified standard model, etc., is also discussed for comparison.

  17. Insights on some chiral smectic phases

    Indian Academy of Sciences (India)

    journal of. August 2003 physics pp. 285–295. Insights on some chiral ... Liquid crystals; smectics; chirality; frustrated phases; twist grain boundary phases. ... molecules are more or less packed in layers and smectic phases can be seen ..... (imaging plate or CCD camera) which was located at about 300 mm from the sample.

  18. New Polymeric Membranes for Organic Solvent Nanofiltration

    KAUST Repository

    Aburabie, Jamaliah

    2017-05-01

    The focus of this dissertation was the development, synthesis and modification of polymers for the preparation of membranes for organic solvent nanofiltration. High chemical stability in a wide range of solvents was a key requirement. Membranes prepared from synthesized polymers as well as from commercial polymers were designed and chemically modified to reach OSN requirements. A solvent stable thin-film composite (TFC) membrane is reported, which is fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate. The membranes exhibited high fluxes towards solvents like THF, DMF and DMSO ranging around 20 L/m2 h at 5 bar with a MWCO of around 1000 g/mol. Ultrafiltration PTSC membranes were prepared by non-solvent induced phase separation and crosslinked with GPTMS. The crosslinking reaction was responsible for the formation of an inorganic-type-network that tuned the membrane pore size. The crosslinked membranes acquired high solvent stability in DMSO, DMF and THF with a MWCO above 1300 g/mol. Reaction Induced Phase Separation (RIPS) was introduced as a new method for the preparation of skinned asymmetric membranes. These membranes have two distinctive layers with different morphologies both from the same polymer. The top dense layer is composed of chemically crosslinked polymer chains while the bottom layer is a porous structure formed by non-crosslinked polymer chains. Such membranes were tested for vitamin B12 in solvents after either crosslinking the support or dissolving the support and fixing the freestanding membrane on alumina. Pebax® 1657 was utilized for the preparation of composite membranes by simple coating. Porous PAN membranes were coated with Pebax® 1657 which was then crosslinked using TDI. Crosslinked Pebax® membranes show high stability towards ethanol, propanol and acetone. The membranes were also stable in DMF once crosslinked PAN supports were used. Sodium alginate polymer was investigated for the preparation of thin film composite

  19. Decontamination of radioactive contaminated protective wear using dry cleaning solvent

    International Nuclear Information System (INIS)

    Muthiah, Pushpa; Chitra, S.; Paul, Biplob

    2013-01-01

    Liquid waste generated by conventional decontamination of radioactive contaminated cotton protective wear using detergent affects the chemical treatment of the plant. To reduce the generation of aqueous detergent waste, dry cleaning of cotton protective wear, highly soiled with oil and grease towards decontamination was tried with organic solvents. Mineral turpentine oil (MTO) among various other organic solvents was identified as a suitable organic solvent. As MTO leaves characteristic odour on the cloth, various commercial fragrances for the removal of the odour were tried. Application of the optimised dry cleaning solvent and commercial fragrance was adopted in plant scale operation. (author)

  20. Density Changes in the Optimized CSSX Solvent System

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.D.

    2002-11-25

    Density increases in caustic-side solvent extraction (CSSX) solvent have been observed in separate experimental programs performed by different groups of researchers. Such changes indicate a change in chemical composition. Increased density adversely affects separation of solvent from denser aqueous solutions present in the CSSX process. Identification and control of factors affecting solvent density are essential for design and operation of the centrifugal contactors. The goals of this research were to identify the factors affecting solvent density (composition) and to develop correlations between easily measured solvent properties (density and viscosity) and the chemical composition of the solvent, which will permit real-time determination and adjustment of the solvent composition. In evaporation experiments, virgin solvent was subjected to evaporation under quiescent conditions at 25, 35, and 45 C with continuously flowing dry air passing over the surface of the solvent. Density and viscosity were measured periodically, and chemical analysis was performed on the solvent samples. Chemical interaction tests were completed to determine if any chemical reaction takes place over extended contact time that changes the composition and/or physical properties. Solvent and simulant, solvent and strip solution, and solvent and wash solution were contacted continuously in agitated flasks. They were periodically sampled and the density measured (viscosity was also measured on some samples) and then submitted to the Chemical Sciences Division of Oak Ridge National Laboratory for analysis by nuclear magnetic resonance (NMR) spectrometry and high-performance liquid chromatography (HPLC) using the virgin solvent as the baseline. Chemical interaction tests showed that solvent densities and viscosities did not change appreciably during contact with simulant, strip, or wash solution. No effects on density and viscosity and no chemical changes in the solvent were noted within

  1. SOLVENT EFFECT ON PROTONATION OF TPPS IN WATER-DMF ...

    African Journals Online (AJOL)

    2016 Chemical Society of Ethiopia ... Department of Chemistry, Jouybar branch, Islamic Azad University, Jouybar, Iran ... hydrogen bonding interactions between solute and solvent components are mainly responsible for the change in.

  2. Solvent effects on the magnetic shielding of tertiary butyl alcohol

    African Journals Online (AJOL)

    )4 and tetramethyl ammonium cation N(CH3)4(+) have also been presented. KEY WORDS: Solvent effects, Magnetic shielding, Tertiary butyl alcohol, Tertiary butyl amine, Continuum solvation calculations, Chemical shift estimation methods

  3. Chiral tunneling in a twisted graphene bilayer.

    Science.gov (United States)

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

    2013-08-09

    The perfect transmission in a graphene monolayer and the perfect reflection in a Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in a twisted graphene bilayer show an adjustable probability of chiral tunneling for normal incidence: they can be changed from perfect tunneling to partial or perfect reflection, or vice versa, by controlling either the height of the barrier or the incident energy. As well as addressing basic physics about how the chiral fermions with different chiralities tunnel through a barrier, our results provide a facile route to tune the electronic properties of the twisted graphene bilayer.

  4. Hadron properties in chiral sigma model

    International Nuclear Information System (INIS)

    Shen Hong

    2005-01-01

    The modification of hadron masses in nuclear medium is studied by using the chiral sigma model, which is extended to generate the omega meson mass by the sigma condensation in the vacuum in the same way as the nucleon mass. The chiral sigma model provides proper equilibrium properties of nuclear matter. It is shown that the effective masses of both nucleons and omega mesons decrease in nuclear medium, while the effective mass of sigma mesons increases oat finite density in the chiral sigma model. The results obtained in the chiral sigma model are compared with those obtained in the Walecka model, which includes sigma and omega mesons in a non-chiral fashion. (author)

  5. Cosmic chirality both true and false.

    Science.gov (United States)

    Barron, Laurence D

    2012-12-01

    The discrete symmetries of parity P, time reversal T, and charge conjugation C may be used to characterize the properties of chiral systems. It is well known that parity violation infiltrates into ordinary matter via an interaction between the nucleons and electrons, mediated by the Z(0) particle, that lifts the degeneracy of the mirror-image enantiomers of a chiral molecule. Being odd under P but even under T, this P-violating interaction exhibits true chirality and so may induce absolute enantioselection under all circumstances. It has been suggested that CP violation may also infiltrate into ordinary matter via a P-odd, T-odd interaction mediated by the (as yet undetected) axion. This CP-violating interaction exhibits false chirality and so may induce absolute enantioselection in processes far from equilibrium. Both true and false cosmic chirality should be considered together as possible sources of homochirality in the molecules of life. Copyright © 2012 Wiley Periodicals, Inc.

  6. Purex process solvent: literature review

    Energy Technology Data Exchange (ETDEWEB)

    Geier, R.G.

    1979-10-01

    This document summarizes the data on Purex process solvent presently published in a variety of sources. Extracts from these various sources are presented herein and contain the work done, the salient results obtained, and the original, unaltered conclusions of the author of each paper. Three major areas are addressed: solvent stability, solvent quality testing, and solvent treatment processes. 34 references, 44 tables.

  7. Purex process solvent: literature review

    International Nuclear Information System (INIS)

    Geier, R.G.

    1979-10-01

    This document summarizes the data on Purex process solvent presently published in a variety of sources. Extracts from these various sources are presented herein and contain the work done, the salient results obtained, and the original, unaltered conclusions of the author of each paper. Three major areas are addressed: solvent stability, solvent quality testing, and solvent treatment processes. 34 references, 44 tables

  8. Principal chiral model on superspheres

    International Nuclear Information System (INIS)

    Mitev, V.; Schomerus, V.; Quella, T.

    2008-09-01

    We investigate the spectrum of the principal chiral model (PCM) on odd-dimensional superspheres as a function of the curvature radius R. For volume-filling branes on S 3 vertical stroke 2 , we compute the exact boundary spectrum as a function of R. The extension to higher dimensional superspheres is discussed, but not carried out in detail. Our results provide very convincing evidence in favor of the strong-weak coupling duality between supersphere PCMs and OSP(2S+2 vertical stroke 2S) Gross-Neveu models that was recently conjectured by Candu and Saleur. (orig.)

  9. Nuclear forces and chiral theories

    International Nuclear Information System (INIS)

    Friar, J.L.; Washington Univ., Seattle, WA

    1995-01-01

    Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force will also be discussed in this context

  10. Chiral quarks and proton decay

    International Nuclear Information System (INIS)

    Chadha, S.; Daniel, M.; Gounaris, G.J.; Murphy, A.J.

    1984-04-01

    The authors calculate the hadronic matrix elements of baryon decay operators using a chiral effective Lagrangian with quarks, gluons and Goldstone boson fields. The cases where the ΔB=1 operators arise from supersymmetric SU(5) GUT as well as the minimal SU(5) GUT model are studied. In each model the results depend on two parameters. In particular there is a range of values for the two parameters, where the dominant decay modes in the minimal SU(5) GUT are: p→etae + and n→π - e + . (author)

  11. Method for Selection of Solvents for Promotion of Organic Reactions

    DEFF Research Database (Denmark)

    Gani, Rafiqul; Jiménez-González, Concepción; Constable, David J.C.

    2005-01-01

    is to produce, for a given reaction, a short list of chemicals that could be considered as potential solvents, to evaluate their performance in the reacting system, and, based on this, to rank them according to a scoring system. Several examples of application are given to illustrate the main features and steps......A method to select appropriate green solvents for the promotion of a class of organic reactions has been developed. The method combines knowledge from industrial practice and physical insights with computer-aided property estimation tools for selection/design of solvents. In particular, it employs...... estimates of thermodynamic properties to generate a knowledge base of reaction, solvent and environment related properties that directly or indirectly influence the rate and/or conversion of a given reaction. Solvents are selected using a rules-based procedure where the estimated reaction-solvent properties...

  12. Natural Optical Activity of Chiral Epoxides: the Influence of Structure and Environment on the Intrinsic Chiroptical Response

    Science.gov (United States)

    Lemler, Paul M.; Craft, Clayton L.; Vaccaro, Patrick

    2017-06-01

    Chiral epoxides built upon nominally rigid frameworks that incorporate aryl substituents have been shown to provide versatile backbones for asymmetric syntheses designed to generate novel pharmaceutical and catalytic agents. The ubiquity of these species has motivated the present studies of their intrinsic (solvent-free) circular birefringence (CB), the measurement of which serves as a benchmark for quantum-chemical predictions of non-resonant chiroptical behavior and as a beachhead for understanding the often-pronounced mediation of such properties by environmental perturbations (e.g., solvation). The optical rotatory dispersion (or wavelength-resolved CB) of (R)-styrene oxide (R-SO) and (S,S)-phenylpropylene oxide (S-PPO) have been interrogated under ambient solvated and isolated conditions, where the latter efforts exploited the ultrasensitive techniques of cavity ring-down polarimetry. Both of the targeted systems display marked solvation effects as evinced by changes the magnitude and (in the case of R-SO) the sign of the extracted specific optical rotation, with the anomalously large response evoked from S-PPO distinguishing it from other members of the epoxide family. Linear-response calculations of dispersive optical activity have been performed at both density-functional and coupled-cluster levels of theory to unravel the structural and electronic origins of experimental findings, thereby suggesting the possible involvement of hindered torsional motion along dihedral coordinates adjoining phenyl and epoxide moieties.

  13. Homochiral Acyl Isocyanates as Diagnostic NMR Probes for the Enantiomeric Purity of Chiral Alcohols

    Directory of Open Access Journals (Sweden)

    Gregory H. P. Roos

    2000-12-01

    Full Text Available The first reported acyl and sulfonylisocyanates were developed and tested in reactions with chiral alcohols to afford diastereomeric carbamates. NMR analysis of these investigates the chemical shift discrimination that would allow these activated isocyanates to be used as diagnostic probes of enantiomeric purity.

  14. Synthesis and characterization of mixed ligand chiral nanoclusters

    KAUST Repository

    Guven, Zekiye P.

    2016-06-22

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

  15. Synthesis and characterization of mixed ligand chiral nanoclusters

    KAUST Repository

    Guven, Zekiye P.; Ustbas, Burcin; Harkness, Kellen M.; Coskun, Hikmet; Joshi, Chakra Prasad; Besong, Tabot M.D.; Stellacci, Francesco; Bakr, Osman; Akbulut, Ozge

    2016-01-01

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

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

    Science.gov (United States)

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

    2009-12-03

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

  17. Chiral symmetry breaking and cooling in lattice QCD

    International Nuclear Information System (INIS)

    Woloshyn, R.M.; Lee, F.X.

    1995-08-01

    Chiral symmetry breaking is calculated as a function of cooling in quenched lattice QCD. A non-zero signal is found for the chiral condensate beyond one hundred cooling steps, suggesting that there is chiral symmetry breaking associated with instantons. Quantitatively, the chiral condensate in cooled gauge field configurations is small compared to the value without cooling. (author) 7 refs., 1 tab., 3 figs

  18. A Review on Chiral Chromatography and its Application to the ...

    African Journals Online (AJOL)

    MoZarD

    amounts of material and is for measuring the relative proportions of ... the stationary phase must themselves be made chiral, giving differing ... electrophoretic medium that change it to chiral mobile phase (Eliel, et ... column containing a chiral stationary phase is also called a chiral ... densitometry, and a TLC method for the.

  19. Separation by solvent extraction

    International Nuclear Information System (INIS)

    Holt, C.H. Jr.

    1976-01-01

    In a process for separating fission product values from U and Pu values contained in an aqueous solution, an oxidizing agent is added to the solution to secure U and Pu in their hexavalent state. The aqueous solution is contacted with a substantially water-immiscible organic solvent with agitation while the temperature is maintained at from -1 to -2 0 C until the major part of the water present is frozen. The solid ice phase is continuously separated as it is formed and a remaining aqueous liquid phase containing fission product values and a solvent phase containing Pu and U values are separated from each other. The last obtained part of the ice phase is melted and added to the separated liquid phase. The resulting liquid is treated with a new supply of solvent whereby it is practically depleted of U and Pu

  20. Nucleic acids, proteins, and chirality

    Science.gov (United States)

    Usher, D. A.; Profy, A. T.; Walstrum, S. A.; Needels, M. C.; Bulack, S. C.; Lo, K. M.

    1984-01-01

    The present investigation is concerned with experimental results related, in one case, to the chirality of nucleotides, and, in another case, to the possibility of a link between the chirality of nucleic acids, and that of peptides. It has been found that aminoacylation of the 'internal' hydroxyl group of a dinucleoside monophosphate can occur stereoselectively. However, this reaction has not yet been made a part of a working peptide synthesis scheme. The formation and cleavage of oligonucleotides is considered. In the event of the formation of a helical complex between the oligonucleotide and the polymer, 1-prime,5-prime-bonds in the oligomer are found to become more resistant towards cleavage. The conditions required for peptide bond formation are examined, taking into account the known structures of RNA and possible mechanisms for prebiotic peptide bond formation. The possibility is considered that the 2-prime,5-prime-internucleotide linkage could have played an important part in the early days of biological peptide synthesis.

  1. Examination of new chiral smectics with four aromatic rings

    Science.gov (United States)

    Żurowska, Magdalena; Czerwiński, Michał; Dziaduszek, Jerzy; Filipowicz, Marek

    2018-05-01

    This paper presents the results of the study of four chiral mesogens with the acronym (4X1X2). The investigated compounds might be of interest for use as components of multicomponent mixtures useful in technical devices. The compounds have high chemical stability. Their mesomorphic properties were tested by means of polarizing optical microscopy and differential scanning calorimetry. The helical pitch of the prepared compounds and mixtures was estimated using the selective reflection method. Their phase smectic layer structure and usefulness for formulation of multicomponent antiferroelectric mixtures were then reported.

  2. Hazardous Solvent Substitution Data System tutorial

    International Nuclear Information System (INIS)

    Twitchell, K.E.; Skinner, N.L.

    1993-07-01

    This manual is the tutorial for the Hazardous Solvent Substitution Data System (HSSDS), an online, comprehensive system of information on alternatives to hazardous solvents and related subjects. The HSSDS data base contains product information, material safety data sheets, toxicity reports, usage reports, biodegradable data, product chemical element lists, and background information on solvents. HSSDS use TOPIC reg-sign to search for information based on a query defined by the user. TOPIC provides a full text retrieval of unstructured source documents. In this tutorial, a series of lessons is provided that guides the user through basic steps common to most queries performed with HSSDS. Instructions are provided for both window-based and character-based applications

  3. Hierarchical chirality transfer in the growth of Towel Gourd tendrils

    Science.gov (United States)

    Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

    2013-01-01

    Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties. PMID:24173107

  4. Finite density two color chiral perturbation theory revisited

    Science.gov (United States)

    Adhikari, Prabal; Beleznay, Soma B.; Mannarelli, Massimo

    2018-06-01

    We revisit two-color, two-flavor chiral perturbation theory at finite isospin and baryon density. We investigate the phase diagram obtained varying the isospin and the baryon chemical potentials, focusing on the phase transition occurring when the two chemical potentials are equal and exceed the pion mass (which is degenerate with the diquark mass). In this case, there is a change in the order parameter of the theory that does not lend itself to the standard picture of first order transitions. We explore this phase transition both within a Ginzburg-Landau framework valid in a limited parameter space and then by inspecting the full chiral Lagrangian in all the accessible parameter space. Across the phase transition between the two broken phases the order parameter becomes an SU(2) doublet, with the ground state fixing the expectation value of the sum of the magnitude squared of the pion and the diquark fields. Furthermore, we find that the Lagrangian at equal chemical potentials is invariant under global SU(2) transformations and construct the effective Lagrangian of the three Goldstone degrees of freedom by integrating out the radial fluctuations.

  5. Chiral soliton lattice and charged pion condensation in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, Tomáš [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Yamamoto, Naoki [Department of Physics, Keio University,Yokohama 223-8522 (Japan)

    2017-04-21

    The Chiral Soliton Lattice (CSL) is a state with a periodic array of topological solitons that spontaneously breaks parity and translational symmetries. Such a state is known to appear in chiral magnets. We show that CSL also appears as a ground state of quantum chromodynamics at nonzero chemical potential in a magnetic field. By analyzing the fluctuations of the CSL, we furthermore demonstrate that in strong but achievable magnetic fields, charged pions undergo Bose-Einstein condensation. Our results, based on a systematic low-energy effective theory, are model-independent and fully analytic.

  6. Supersymmetric chiral electrodynamics as a renormalized theory

    International Nuclear Information System (INIS)

    Ansel'm, A.A.; Iogansen, A.A.

    1991-01-01

    It is well know that the QED of chiral fermions is a nonrenormalizable theory, inasmuch as the gauge current in it is not conserved because of the presence of an anomaly. It is evident that in this theory unitarity is also violated. The principal object of investigation in the present paper is supersymmetric chiral QED, supersymmetric QED is a renormalizable theory. This happens because the radiative corrections generate here a charged current of a chiral fermion that appears in the chiral (i.e., longitudinal) part of the vector supermultiplet. At first sight, the chiral part of the vector multiplet is unphysical and contains only supergauge degrees of freedom. However, this is valid only at the classical level, whereas, because of the anomaly, the radiative corrections lead to nonconservation of the gauge current, as a result of which the degrees of freedom associated with the chiral part of the vector multiplet become physical. On the other hand, owing to the nonconservation of the gauge charge, the apparently neutral fermion appearing int he chiral (longitudinal) part of the vector superfield becomes charged

  7. NMR and Solvent Effect Study on the Thymine-Adenine-Thymine ...

    African Journals Online (AJOL)

    ... discussed about the plotted graphs of relative energies versus dielectric constants of our considered solvents. Thus, we can drastically conclude that the dielectric permittivity of the solvent is a key factor that determines the chemical behavior of DNA in solution. Keywords: TAT sequence; solvent effect; NMR parameters; ...

  8. Chiral polarization scale of QCD vacuum and spontaneous chiral symmetry breaking

    International Nuclear Information System (INIS)

    Alexandru, Andrei; Horv, Ivan

    2013-01-01

    It has recently been found that dynamics of pure glue QCD supports the low energy band of Dirac modes with local chiral properties qualitatively different from that of a bulk: while bulk modes suppress chirality relative to statistical independence between left and right, the band modes enhance it. The width of such chirally polarized zone – chiral polarization scale bigwedge ch – has been shown to be finite in the continuum limit at fixed physical volume. Here we present evidence that bigwedge ch remains non-zero also in the infinite volume, and is therefore a dynamical scale in the theory. Our experiments in N f = 2+1 QCD support the proposition that the same holds in the massless limit, connecting bigwedge ch to spontaneous chiral symmetry breaking. In addition, our results suggest that thermal agitation in quenched QCD destroys both chiral polarization and condensation of Dirac modes at the same temperature T ch > T c .

  9. Ions, solutes and solvents, oh my!

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Daniel David [Iowa State Univ., Ames, IA (United States)

    2009-08-01

    Modern methods in ab initio quantum mechanics have become efficient and accurate enough to study many gas-phase systems. However, chemists often work in the solution phase. The presence of solvent molecules has been shown to affect reaction mechanisms1, lower reaction energy barriers2, participate in energy transfer with the solute3 and change the physical properties of the solute4. These effects would be overlooked in simple gas phase calculations. Careful study of specific solvents and solutes must be done in order to fully understand the chemistry of the solution phase. Water is a key solvent in chemical and biological applications. The properties of an individual water molecule (a monomer) and the behavior of thousands of molecules (bulk solution) are well known for many solvents. Much is also understood about aqueous microsolvation (small clusters containing ten water molecules or fewer) and the solvation characteristics when bulk water is chosen to solvate a solute. However, much less is known about how these properties behave as the cluster size transitions from the microsolvated cluster size to the bulk. This thesis will focus on species solvated with water clusters that are large enough to exhibit the properties of the bulk but small enough to consist of fewer than one hundred solvent molecules. New methods to study such systems will also be presented.

  10. The paradigm of Pseudodual Chiral Models

    International Nuclear Information System (INIS)

    Zachos, C.K.; Curtright, T.L.

    1994-01-01

    This is a synopsis and extension of Phys. Rev. D49 5408 (1994). The Pseudodual Chiral Model illustrates 2-dimensional field theories which possess an infinite number of conservation laws but also allow particle production, at variance with naive expectations-a folk theorem of integrable models. We monitor the symmetries of the pseudodual model, both local and nonlocal, as transmutations of the symmetries of the (very different) usual Chiral Model. We refine the conventional algorithm to more efficiently produce the nonlocal symmetries of the model. We further find the canonical transformation which connects the usual chiral model to its fully equivalent dual model, thus contradistinguishing the pseudodual theory

  11. Recent status of the chiral bag model

    International Nuclear Information System (INIS)

    Hosaka, Atsushi; Toki, Hiroshi.

    1995-01-01

    In this note, recent status of the chiral bag model is presented. As it combines the MIT quark bag model and the Skyrme model, the chiral bag model interpolates the two models smoothly as a function of the chiral bag radius R. The correct limit of R → ∞ is reproduced by including the higher order terms in the Ω expansion of the cranking method. It resolves the so-called small g A problem in a class of models where the semiclassical method is used. (author)

  12. A nonlocal model of chiral dynamics

    International Nuclear Information System (INIS)

    Holdom, B.; Terning, J.; Verbeek, K.

    1989-01-01

    We consider a nonlocal generalization of the nonlinear σ model. Our chirally symmetric model couples quarks with self-energy Σ(p) to Goldstone bosons (GBs). By integrating out the quarks we obtain a chiral lagrangian, the parameters of which are finite integrals of Σ(p). We find that chiral symmetry is not sufficient to derive the well-known Pagels-Stokar formula for the GB decay constant. We reproduce the Wess-Zumino term and we illustrate the dependence of other four derivative coefficients on Σ(p). (orig.)

  13. Influence of different water-ethanol solvent systems on the spectroscopic and physico-chemical properties of the macrocyclic compounds pheophytin and chlorophyll a; Influencia de diferentes sistemas de solvente agua-etanol sobre as propriedades fisico-quimicas e espectroscopicas dos compostos macrociclicos feofitina e clorofila a

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Leonardo M.; Rodrigues, Maira R.; Oliveira, Hueder P. M. de [Universidade Camilo Castelo Branco, Sao Jose dos Campos, SP (Brazil); Lima, Adriana [Universidade do Vale do Paraiba, Sao Jose dos Campos, SP (Brazil); Soares, Rafael R. S.; Batistela, Vagner R.; Gerola, Adriana P.; Hioka, Noboru [Universidade Estadual de Maringa (UEM), PR (Brazil). Dept. de Quimica; Severino, Divinomar; Baptista, Mauricio S. [Universidade de Sao Paulo, (USP), SP (Brazil). Inst. de Quimica; Machado, Antonio Eduardo da Hora [Universidade Federal de Uberlandia (UFU), MG (Brazil). Inst. de Quimica

    2010-07-01

    This work focus on the influence of solvent on the photophysical properties of chlorophyll a and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds. (author)

  14. Fluxionally chiral DMAP catalysts: kinetic resolution of axially chiral biaryl compounds.

    Science.gov (United States)

    Ma, Gaoyuan; Deng, Jun; Sibi, Mukund P

    2014-10-27

    Can organocatalysts that incorporate fluxional groups provide enhanced selectivity in asymmetric transformations? To address this issue, we have designed chiral 4-dimethylaminopyridine (DMAP) catalysts with fluxional chirality. These catalysts were found to be efficient in promoting the acylative kinetic resolution of secondary alcohols and axially chiral biaryl compounds with selectivity factors of up to 37 and 51, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources.

    Science.gov (United States)

    Clark, James H; Farmer, Thomas J; Hunt, Andrew J; Sherwood, James

    2015-07-28

    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents.

  16. Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources

    Science.gov (United States)

    Clark, James H.; Farmer, Thomas J.; Hunt, Andrew J.; Sherwood, James

    2015-01-01

    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents. PMID:26225963

  17. Organic solvent topical report

    Energy Technology Data Exchange (ETDEWEB)

    COWLEY, W.L.

    1999-05-13

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an organic solvent fire is within risk evaluation guidelines. This report updates information contained in Analysis of Consequences of Postulated Solvent Fires in Hanford Site Waste Tanks. WHC-SD-WM-CN-032. Rev. 0A (Cowley et al. 1996). However, this document will not replace Cowley et al (1996) as the primary reference for the Basis for Interim Operation (BIO) until the recently submitted BIO amendment (Hanson 1999) is approved by the US Department of Energy. This conclusion depends on the use of controls for preventing vehicle fuel fires and for limiting the use of flame cutting in areas where hot metal can fall on the waste surface.The required controls are given in the Tank Waste Remediation System Technical Safety Requirements (Noorani 1997b). This is a significant change from the conclusions presented in Revision 0 of this report. Revision 0 of this calcnote concluded that some organic solvent fire scenarios exceeded risk evaluation guidelines, even with controls imposed.

  18. Organic solvent topical report

    International Nuclear Information System (INIS)

    COWLEY, W.L.

    1999-01-01

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an organic solvent fire is within risk evaluation guidelines. This report updates information contained in Analysis of Consequences of Postulated Solvent Fires in Hanford Site Waste Tanks. WHC-SD-WM-CN-032. Rev. 0A (Cowley et al. 1996). However, this document will not replace Cowley et al (1996) as the primary reference for the Basis for Interim Operation (BIO) until the recently submitted BIO amendment (Hanson 1999) is approved by the US Department of Energy. This conclusion depends on the use of controls for preventing vehicle fuel fires and for limiting the use of flame cutting in areas where hot metal can fall on the waste surface.The required controls are given in the Tank Waste Remediation System Technical Safety Requirements (Noorani 1997b). This is a significant change from the conclusions presented in Revision 0 of this report. Revision 0 of this calcnote concluded that some organic solvent fire scenarios exceeded risk evaluation guidelines, even with controls imposed

  19. Surface Chirality of Gly-Pro Dipeptide Adsorbed on a Cu(110) Surface.

    Science.gov (United States)

    Cruguel, Hervé; Méthivier, Christophe; Pradier, Claire-Marie; Humblot, Vincent

    2015-07-01

    The adsorption of chiral Gly-Pro dipeptide on Cu(110) has been characterized by combining in situ polarization modulation infrared reflection absorption spectroscopy (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS). The chemical state of the dipeptide, and its anchoring points and adsorption geometry, were determined at various coverage values. Gly-Pro molecules are present on Cu(110) in their anionic form (NH2 /COO(-)) and adsorb under a 3-point binding via both oxygen atoms of the carboxylate group and via the nitrogen atom of the amine group. Low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) have shown the presence of an extended 2D chiral array, sustained via intermolecular H-bonds interactions. Furthermore, due to the particular shape of the molecule, only one homochiral domain is formed, creating thus a truly chiral surface. © 2015 Wiley Periodicals, Inc.

  20. Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

    Energy Technology Data Exchange (ETDEWEB)

    Kalaydzhyan, Tigran, E-mail: tigran@caltech.edu [Department of Physics, University of Illinois, 845 W Taylor Street, Chicago, IL 60607 (United States); Jet Propulsion Laboratory, 4800 Oak Grove Dr, M/S 298, Pasadena, CA 91109 (United States); Murchikova, Elena [TAPIR, California Institute of Technology, MC 350-17, Pasadena, CA 91125 (United States)

    2017-06-15

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

  1. Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

    International Nuclear Information System (INIS)

    Kalaydzhyan, Tigran; Murchikova, Elena

    2017-01-01

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

  2. Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

    Directory of Open Access Journals (Sweden)

    Tigran Kalaydzhyan

    2017-06-01

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

  3. Determining chiral couplings at NLO

    International Nuclear Information System (INIS)

    Rosell, Ignasi

    2007-01-01

    We present a general method that allows to estimate the low-energy constants of Chiral Perturbation Theory up to next-to-leading corrections in the 1/N C expansion, that is, keeping full control of the renormalization scale dependence. As a first step we have determined L 8 and C 38 , the couplings related to the difference of the two-point correlation functions of two scalar and pseudoscalar currents, L 8 r (μ 0 ) = (0.6±0.4)·10 -3 and C 38 r (μ 0 ) = (2±6)·10 -6 , with μ 0 0.77 GeV. As in many effective approaches, one of the main ingredients of this method is the matching procedure: some comments related to this topic are presented here

  4. Dynamics of inhomogeneous chiral condensates

    Science.gov (United States)

    Carlomagno, Juan Pablo; Krein, Gastão; Kroff, Daniel; Peixoto, Thiago

    2018-01-01

    We study the dynamics of the formation of inhomogeneous chirally broken phases in the final stages of a heavy-ion collision, with particular interest on the time scales involved in the formation process. The study is conducted within the framework of a Ginzburg-Landau time evolution, driven by a free energy functional motivated by the Nambu-Jona-Lasinio model. Expansion of the medium is modeled by one-dimensional Bjorken flow and its effect on the formation of inhomogeneous condensates is investigated. We also use a free energy functional from a nonlocal Nambu-Jona-Lasinio model which predicts metastable phases that lead to long-lived inhomogeneous condensates before reaching an equilibrium phase with homogeneous condensates.

  5. Chiral equations and fiber bundles

    International Nuclear Information System (INIS)

    Mateos, T.; Becerril, R.

    1992-01-01

    Using the hypothesis g = g (lambda i ), the chiral equations (rhog, z g -1 ), z -bar + (rhog, z -barg -1 ), z = 0 are reduced to a Killing equation of a p-dimensional space V p , being lambda i lambda i (z, z-bar) 'geodesic' parameters of V p . Supposing that g belongs to a Lie group G, one writes the corresponding Lie algebra elements (F) in terms of the Killing vectors of V p and the generators of the subalgebra of F of dimension d = dimension of the Killing space. The elements of the subalgebras belong to equivalence classes which in the respective group form a principal fiber bundle. This is used to integrate the matrix g in terms of the complex variables z and z-bar ( Author)

  6. Critical constraints on chiral hierarchies

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  7. Axions from chiral family symmetry

    International Nuclear Information System (INIS)

    Chang, D.; Pal, P.B.; Maryland Univ., College Park; Senjanovic, G.

    1985-01-01

    We investigate the possibility that family symmetry, Gsub(F), is spontaneously broken chiral global symmetry. We classify the interesting cases when family symmetry can result in an automatic Peccei-Quinn symmetry U(1)sub(PQ) and thus provide a solution to the strong CP problem. The result disfavors having two or four families. For more than four families, U(1)sub(PQ) is in general automatic. In the case of three families, a unique Higgs sector allows U(1)sub(PQ) in the simplest case of Gsub(F)=[SU(3)] 3 . Cosmological consideration also puts strong constraint on the number of families. For Gsub(F)=[SU(N)] 3 cosmology singles out the three-family (N=3) case as a unique solution if there are three light neutrinos. Possible implication of decoupling theorem as applied to family symmetry breaking is also discussed. (orig.)

  8. Algebraic structure of chiral anomalies

    International Nuclear Information System (INIS)

    Stora, R.

    1985-09-01

    I will describe first the algebraic aspects of chiral anomalies, exercising however due care about the topological delicacies. I will illustrate the structure and methods in the context of gauge anomalies and will eventually make contact with results obtained from index theory. I will go into two sorts of generalizations: on the one hand, generalizing the algebraic set up yields e.g. gravitational and mixed gauge anomalies, supersymmetric gauge anomalies, anomalies in supergravity theories; on the other hand most constructions applied to the cohomologies which characterize anomalies easily extend to higher cohomologies. Section II is devoted to a description of the general set up as it applies to gauge anomalies. Section III deals with a number of algebraic set ups which characterize more general types of anomalies: gravitational and mixed gauge anomalies, supersymmetric gauge anomalies, anomalies in supergravity theories. It also includes brief remarks on σ models and a reminder on the full BRST algebra of quantized gauge theories

  9. Biaxiality of chiral liquid crystals

    International Nuclear Information System (INIS)

    Longa, L.; Trebin, H.R.; Fink, W.

    1993-10-01

    Using extended deGennes-Ginzburg-Landau free energy expansion in terms of the anisotropic part of the dielectric tensor field Q αβ (χ) a connection between the phase biaxiality and the stability of various chiral liquid crystalline phases is studied. In particular the cholesteric phase, the cubic Blue Phases and the phases characterized by an icosahedral space group symmetry are analysed in detail. Also a general question concerning the applicability of the mean-field approximation in describing the chiral phases is addressed. By an extensive study of the model over a wide range of the parameters a new class of phenomena, not present in the original deGennes-Ginzburg-Landau model, has been found. These include: a) re-entrant phase transitions between the cholesteric and the cubic blue phases and b) the existence of distinct phases of the same symmetry but of different biaxialities. The phase biaxiality serves here as an extra scalar order parameter. Furthermore, it has been shown that due to the presence of the competing bulk terms in the free energy, the stable phases may acquire a large degree of biaxiality, also in liquid crystalline materials composed of effectively uniaxial molecules. A study of icosahedral space group symmetries gives a partial answer to the question as to whether an icosahedral quasicrystalline liquid could be stabilized in liquid crystals. Although, in general, the stability of icosahedral structures could be enhanced by the extra terms in the free energy no absolutely stable icosahedral phase has been found. (author). 16 refs, 3 figs, 1 tab

  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. Stereoselective separation of β-adrenergic blocking agents containing two chiral centers by countercurrent chromatography.

    Science.gov (United States)

    Lv, Liqiong; Bu, Zhisi; Lu, Mengxia; Wang, Xiaoping; Yan, Jizhong; Tong, Shengqiang

    2017-09-01

    Four β-adrenergic blocking agents, including 1-[(1-methylethyl)amino]-3-phenoxy-2-propanol (1), 1-[(1-methylethyl)amino]-3-(3-methylphenoxy)-2-propanol (2), 1,1'-[1,4-phenylenebis(oxy)]bis[3-[(1-methylethyl)amino]-2-propanol (3) and 1,1'-[(4-methyl-1,2-phenylene)bis(oxy)]bis[3-[(1-methylethyl)amino]-2-propanol (4), were stereoselectively separated by countercurrent chromatography using di-n-hexyl l-tartrate and boric acid as chiral selector. The compounds (3) and (4) have four optical isomers since they contained two chiral centers. A two-phase solvent system composed of chloroform-0.05molL -1 of acetate buffer containing 0.10molL -1 of boric acid (1:1, v/v) was selected, in which 0.10molL -1 of di-n-hexyl l-tartrate was added in the organic phase as chiral selector. 20-42mg of each racemate was stereoselectively separated by countercurrent chromatography in a single run with high purity of 96-98%, and the recovery of each separated compound reached around 87-93%. This is the first time report on successful stereoselective separation of optical isomeric compounds containing two chiral centers by countercurrent chromatography. At the same time, a chiral stationary phase was screened for analytical stereoselective separation of compounds (3) and (4) by high performance liquid chromatography. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Symmetry properties of chiral carbon nanotubes

    International Nuclear Information System (INIS)

    Jishi, R.A.; Venkataraman, L.; Dresselhaus, M.S.; Dresselhaus, G.

    1995-01-01

    The method of zone folding is applied to the calculation of the phonon mode frequencies in carbon nanotubules. The Raman and infrared-active mode frequencies are determined for nanotubules of different diameters and chiralities

  13. Parity doublers in chiral potential quark models

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  14. Chiral Selectivity as a Bridge to Homochirality

    Science.gov (United States)

    Burton, A. S.; Berger, E. L.

    2017-07-01

    We investigate the transition from racemic, abiotic chemistry to homochiral polymers used in proteins; exploring the polymerization behavior of chiral amino acids to determine if they show a preference for homochiral or heterochiral polymerization.

  15. Functional chiral hydrogen-bonded assemblies

    NARCIS (Netherlands)

    Mateos timoneda, Miguel

    2005-01-01

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

  16. Chiral Pesticide Pharmacokinetics: A Range of Values

    Science.gov (United States)

    Approximately 30% of pesticides are chiral and used as mixtures of two or more stereoisomers. In biological systems, these stereoisomers can exhibit significantly different pharmacokinetics (absorption, distribution, metabolism, and elimination). In spite of these differences, th...

  17. Chiral dynamics with (non)strange quarks

    International Nuclear Information System (INIS)

    Kubis, Bastian; Meißner, Ulf-G.

    2017-01-01

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

  18. Chiral dynamics with (non)strange quarks

    Science.gov (United States)

    Kubis, Bastian; Meißner, Ulf-G.

    2017-01-01

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

  19. Chiral unitary theory: Application to nuclear problems

    Indian Academy of Sciences (India)

    Chiral unitary theory: Application to nuclear problems ... Physics Department, Nara Women University, Nara, Japan. 5 ... RCNP, Osaka University, Osaka, Japan ...... We acknowledge partial financial support from the DGICYT under contract ...

  20. Unified Chiral models of mesons and baryons

    International Nuclear Information System (INIS)

    Mendez-Galain, R.; Ripka, G.

    1990-01-01

    Unified Chiral models of mesons and baryons are presented. Emphasis is placed on the underlying quark structure of hadrons including the Skyrmion. The Nambu Jona-Lasinio model with vector mesons is discussed