WorldWideScience

Sample records for anions

  1. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  2. Anions in Cometary Comae

    Science.gov (United States)

    Charnley, Steven B.

    2011-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions 0-, OH-, C-, CH- and CN- have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu (Chaizy et al. 1991). Organic molecular anions are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas-phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been explored. We present details of the first attempt to model the chemistry of anions in cometary comae. Based on the combined chemical and hydro dynamical model of Rodgers & Charnley (2002), we investigate the role of large carbon-chain anions in cometary coma chemistry. We calculate the effects of these anions on coma thermodynamics, charge balance and examine their impact on molecule formation.

  3. Intrinsic anion oxidation potentials.

    Science.gov (United States)

    Johansson, Patrik

    2006-11-01

    Anions of lithium battery salts have been investigated by electronic structure calculations with the objective to find a computational measure to correlate with the observed (in)stability of nonaqueous lithium battery electrolytes vs oxidation often encountered in practice. Accurate prediction of intrinsic anion oxidation potentials is here made possible by computing the vertical free energy difference between anion and neutral radical (Delta Gv) and further strengthened by an empirical correction using only the anion volume as a parameter. The 6-311+G(2df,p) basis set, the VSXC functional, and the C-PCM SCRF algorithm were used. The Delta Gv calculations can be performed using any standard computational chemistry software. PMID:17078600

  4. Anion-π catalysis.

    Science.gov (United States)

    Zhao, Yingjie; Beuchat, César; Domoto, Yuya; Gajewy, Jadwiga; Wilson, Adam; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2014-02-01

    The introduction of new noncovalent interactions to build functional systems is of fundamental importance. We here report experimental and theoretical evidence that anion-π interactions can contribute to catalysis. The Kemp elimination is used as a classical tool to discover conceptually innovative catalysts for reactions with anionic transition states. For anion-π catalysis, a carboxylate base and a solubilizer are covalently attached to the π-acidic surface of naphthalenediimides. On these π-acidic surfaces, transition-state stabilizations up to ΔΔGTS = 31.8 ± 0.4 kJ mol(-1) are found. This value corresponds to a transition-state recognition of KTS = 2.7 ± 0.5 μM and a catalytic proficiency of 3.8 × 10(5) M(-1). Significantly increasing transition-state stabilization with increasing π-acidity of the catalyst, observed for two separate series, demonstrates the existence of "anion-π catalysis." In sharp contrast, increasing π-acidity of the best naphthalenediimide catalysts does not influence the more than 12 000-times weaker substrate recognition (KM = 34.5 ± 1.6 μM). Together with the disappearance of Michaelis-Menten kinetics on the expanded π-surfaces of perylenediimides, this finding supports that contributions from π-π interactions are not very important for anion-π catalysis. The linker between the π-acidic surface and the carboxylate base strongly influences activity. Insufficient length and flexibility cause incompatibility with saturation kinetics. Moreover, preorganizing linkers do not improve catalysis much, suggesting that the ideal positioning of the carboxylate base on the π-acidic surface is achieved by intramolecular anion-π interactions rather than by an optimized structure of the linker. Computational simulations are in excellent agreement with experimental results. They confirm, inter alia, that the stabilization of the anionic transition states (but not the neutral ground states) increases with the π-acidity of the

  5. Anion-π catalysis.

    Science.gov (United States)

    Zhao, Yingjie; Beuchat, César; Domoto, Yuya; Gajewy, Jadwiga; Wilson, Adam; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2014-02-01

    The introduction of new noncovalent interactions to build functional systems is of fundamental importance. We here report experimental and theoretical evidence that anion-π interactions can contribute to catalysis. The Kemp elimination is used as a classical tool to discover conceptually innovative catalysts for reactions with anionic transition states. For anion-π catalysis, a carboxylate base and a solubilizer are covalently attached to the π-acidic surface of naphthalenediimides. On these π-acidic surfaces, transition-state stabilizations up to ΔΔGTS = 31.8 ± 0.4 kJ mol(-1) are found. This value corresponds to a transition-state recognition of KTS = 2.7 ± 0.5 μM and a catalytic proficiency of 3.8 × 10(5) M(-1). Significantly increasing transition-state stabilization with increasing π-acidity of the catalyst, observed for two separate series, demonstrates the existence of "anion-π catalysis." In sharp contrast, increasing π-acidity of the best naphthalenediimide catalysts does not influence the more than 12 000-times weaker substrate recognition (KM = 34.5 ± 1.6 μM). Together with the disappearance of Michaelis-Menten kinetics on the expanded π-surfaces of perylenediimides, this finding supports that contributions from π-π interactions are not very important for anion-π catalysis. The linker between the π-acidic surface and the carboxylate base strongly influences activity. Insufficient length and flexibility cause incompatibility with saturation kinetics. Moreover, preorganizing linkers do not improve catalysis much, suggesting that the ideal positioning of the carboxylate base on the π-acidic surface is achieved by intramolecular anion-π interactions rather than by an optimized structure of the linker. Computational simulations are in excellent agreement with experimental results. They confirm, inter alia, that the stabilization of the anionic transition states (but not the neutral ground states) increases with the π-acidity of the

  6. Vanadogermanate cluster anions.

    Science.gov (United States)

    Whitfield, T; Wang, X; Jacobson, A J

    2003-06-16

    Three novel vanadogermanate cluster anions have been synthesized by hydrothermal reactions. The cluster anions are derived from the (V(18)O(42)) Keggin cluster shell by substitution of V=O(2+) "caps" by Ge(2)O(OH)(2)(4+) species. In Cs(8)[Ge(4)V(16)O(42)(OH)(4)].4.7H(2)O, 1, (monoclinic, space group C2/c (No. 15), Z = 8, a = 44.513(2) A, b = 12.7632(7) A, c = 22.923(1) A, beta = 101.376(1) degrees ) and (pipH(2))(4)(pipH)(4)[Ge(8)V(14)O(50).(H(2)O)] (pip = C(4)N(2)H(10)), 2 (tetragonal, space group P4(2)/nnm (No. 134), Z = 2, a = 14.9950(7) A, c = 18.408(1) A), two and four VO(2+) caps are replaced, respectively, and each cluster anion encapsulates a water molecule. In K(5)H(8)Ge(8)V(12)SO(52).10H(2)O, 3, (tetragonal, space group I4/m (No. 87), Z = 2, a = 15.573(1) A, c = 10.963(1) A), four VO(2+) caps are replaced by Ge(2)O(OH)(2)(4+) species, and an additional two are omitted. The cluster ion in 3 contains a sulfate anion disordered over two positions. The cluster anions are analogous to the vanadoarsenate anions [V(18)(-)(n)()As(2)(n)()O(42)(X)](m)(-) (X = SO(3), SO(4), Cl; n = 3, 4) previously reported. PMID:12793808

  7. Potentiometric anion selective sensors

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Reinhoudt, David N.

    1999-01-01

    In comparison with selective receptors (and sensors) for cationic species, work on the selective complexation and detection of anions is of more recent date. There are three important components for a sensor, a transducer element, a membrane material that separates the transducer element and the aqu

  8. Anion Ordering in Bichalcogenides

    Directory of Open Access Journals (Sweden)

    Martin Valldor

    2016-07-01

    Full Text Available This review contains recent developments and new insights in the research on inorganic, crystalline compounds with two different chalcogenide ions (bichalcogenides. Anion ordering is used as a parameter to form structural dimensionalities as well as local- and global-electric polarities. The reason for the electric polarity is that, in the heterogeneous bichalcogenide lattice, the individual bond-lengths between cations and anions are different from those in a homogeneous anion lattice. It is also shown that heteroleptic tetrahedral and octahedral coordinations offer a multitude of new crystal fields and coordinations for involved cations. This coordination diversity in bichalcogenides seems to be one way to surpass electro-chemical redox potentials: three oxidation states of a single transition metal can be stabilized, e.g., Ba15V12S34O3. A new type of disproportionation, related to coordination, is presented and results from chemical pressure on the bichalcogenide lattices of (La,CeCrS2O, transforming doubly [CrS3/3S2/2O1/1]3− (5+1 into singly [CrS4/2S2/3]7/3− (6+0 and [CrS4/3O2/1]11/3− (4+2 coordinations. Also, magnetic anisotropy is imposed by the anion ordering in BaCoSO, where magnetic interactions via S or O occur along two different crystallographic directions. Further, the potential of the anion lattice is discussed as a parameter for future materials design.

  9. Resonant spectra of quadrupolar anions

    CERN Document Server

    Fossez, K; Nazarewicz, W; Michel, N; Garrett, W R; Płoszajczak, M

    2016-01-01

    In quadrupole-bound anions, an extra electron is attached at a sufficiently large quadrupole moment of a neutral molecule, which is lacking a permanent dipole moment. The nature of the bound states and low-lying resonances of such anions is of interest for understanding the threshold behavior of open quantum systems in general. In this work, we investigate the properties of quadrupolar anions as extreme halo systems, the formation of rotational bands, and the transition from a subcritical to supercritical electric quadrupole moment. We solve the electron-plus-molecule problem using a non-adiabatic coupled-channel formalism by employing the Berggren ensemble, which explicitly contains bound states, narrow resonances, and the scattering continuum. We demonstrate that binding energies and radii of quadrupolar anions strictly follow the scaling laws for two-body halo systems. Contrary to the case of dipolar anions, ground-state band of quadrupolar anions smoothly extend into the continuum, and many rotational ban...

  10. Resonant spectra of quadrupolar anions

    Science.gov (United States)

    Fossez, K.; Mao, Xingze; Nazarewicz, W.; Michel, N.; Garrett, W. R.; Płoszajczak, M.

    2016-09-01

    In quadrupole-bound anions, an extra electron is attached at a sufficiently large quadrupole moment of a neutral molecule, which is lacking a permanent dipole moment. The nature of the bound states and low-lying resonances of such anions is of interest for understanding the threshold behavior of open quantum systems in general. In this work, we investigate the properties of quadrupolar anions as halo systems, the formation of rotational bands, and the transition from a subcritical to supercritical electric quadrupole moment. We solve the electron-plus-rotor problem using a nonadiabatic coupled-channel formalism by employing the Berggren ensemble, which explicitly contains bound states, narrow resonances, and the scattering continuum. The rotor is treated as a linear triad of point charges with zero monopole and dipole moments and nonzero quadrupole moment. We demonstrate that binding energies and radii of quadrupolar anions strictly follow the scaling laws for two-body halo systems. Contrary to the case of dipolar anions, ground-state band of quadrupolar anions smoothly extend into the continuum, and many rotational bands could be identified above the detachment threshold. We study the evolution of a bound state of an anion as it dives into the continuum at a critical quadrupole moment and we show that the associated critical exponent is α =2 . Everything considered, quadrupolar anions represent a perfect laboratory for the studies of marginally bound open quantum systems.

  11. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  12. Pentaarylfullerenes as noncoordinating cyclopentadienyl anions

    NARCIS (Netherlands)

    Bouwkamp, Marco W.; Meetsma, Auke

    2009-01-01

    The first example of an early-transition-metal complex involving a pentaarylfullerene was prepared. Instead of half-sandwich complexes, solvent separated ion pairs were obtained in which the pentaarylfullerene moiety acts as noncoordinating cyclopentadienyl anion.

  13. Anion Transport with Chalcogen Bonds.

    Science.gov (United States)

    Benz, Sebastian; Macchione, Mariano; Verolet, Quentin; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2016-07-27

    In this report, we introduce synthetic anion transporters that operate with chalcogen bonds. Electron-deficient dithieno[3,2-b;2',3'-d]thiophenes (DTTs) are identified as ideal to bind anions in the focal point of the σ holes on the cofacial endocyclic sulfur atoms. Anion binding in solution and anion transport across lipid bilayers are found to increase with the depth of the σ holes of the DTT anionophores. These results introduce DTTs and related architectures as a privileged motif to engineer chalcogen bonds into functional systems, complementary in scope to classics such as 2,2'-bipyrroles or 2,2'-bipyridines that operate with hydrogen bonds and lone pairs, respectively. PMID:27433964

  14. Bound anionic states of adenine

    Energy Technology Data Exchange (ETDEWEB)

    Haranczyk, Maciej; Gutowski, Maciej S; Li, Xiang; Bowen, Kit H

    2007-03-20

    Anionic states of nucleic acid bases are involved in DNA damage by low-energy electrons and in charge transfer through DNA. Previous gas phase studies of free, unsolvated nucleic acid base parent anions probed only dipole-bound states, which are not present in condensed phase environments, but did not observe valence anionic states, which for purine bases, are thought to be adiabatically unbound. Contrary to this expectation, we have demonstrated that some thus far ignored tautomers of adenine, which result from enamine-imine transformations, support valence anionic states with electron vertical detachment energies as large as 2.2 eV, and at least one of these anionic tautomers is adiabatically bound. Moreover, we predict that the new anionic tautomers should also dominate in solutions and should be characterized by larger values of electron vertical detachment energy than the canonical valence anion. All of the new-found anionic tautomers might be formed in the course of dissociative electron attachment followed by a hydrogen atom attachment to a carbon atom, and they might affect the structure and properties of DNA and RNA exposed to low-energy electrons. The discovery of these valence anionic states of adenine was facilitated by the development of: (i) a new experimental method for preparing parent anions of nucleic acid bases for photoelectron experiments, and (ii) a new combinatorial/ quantum chemical approach for identification of the most stable tautomers of organic molecules. The computational portion of this work was supported by the: (i) Polish State Committee for Scientific Research (KBN) Grants: DS/8000-4-0140-7 (M.G.) and N204 127 31/2963 (M.H.), (ii) European Social Funds (EFS) ZPORR/2.22/II/2.6/ARP/U/2/05 (M.H.), and (iii) US DOE Office of Biological and Environmental Research, Low Dose Radiation Research Program (M.G.). M.H. holds the Foundation for Polish Science (FNP) award for young scientists. The calculations were performed at the Academic

  15. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-08

    This project seeks to improve the efficiency of the plutonium anion-exchange process for purifying Pu through the development of alternate ion-exchange media. The objective of the project in FY15 was to develop and test a porous foam monolith material that could serve as a replacement for the current anion-exchange resin, Reillex® HPQ, used at the Savannah River Site (SRS) for purifying Pu. The new material provides advantages in efficiency over the current resin by the elimination of diffusive mass transport through large granular resin beads. By replacing the large resin beads with a porous foam there is much more efficient contact between the Pu solution and the anion-exchange sites present on the material. Several samples of a polystyrene based foam grafted with poly(4-vinylpyridine) were prepared and the Pu sorption was tested in batch contact tests.

  16. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Michael Rajamathi; Grace S Thomas; P Vishnu Kamath

    2001-10-01

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange properties together with surface basicity making them materials of importance for many modern applications. In this article, we discuss many different ways of making anionic clays and compare and contrast the rich diversity of this class of materials with the better-known cationic clays.

  17. Anion binding in biological systems

    Science.gov (United States)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  18. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Feiters, Martin C [Department of Organic Chemistry, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Meyer-Klaucke, Wolfram [EMBL Hamburg Outstation at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kostenko, Alexander V; Soldatov, Alexander V [Faculty of Physics, Southern Federal University, Sorge 5, Rostov-na-Donu, 344090 (Russian Federation); Leblanc, Catherine; Michel, Gurvan; Potin, Philippe [Centre National de la Recherche Scientifique and Universite Pierre et Marie Curie Paris-VI, Station Biologique de Roscoff, Place Georges Teissier, BP 74, F-29682 Roscoff cedex, Bretagne (France); Kuepper, Frithjof C [Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, Scotland (United Kingdom); Hollenstein, Kaspar; Locher, Kaspar P [Institute of Molecular Biology and Biophysics, ETH Zuerich, Schafmattstrasse 20, Zuerich, 8093 (Switzerland); Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R, E-mail: m.feiters@science.ru.n [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2009-11-15

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L{sub 3} (2p{sub 3/2}) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  19. Tripodal Receptors for Cation and Anion Sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman,; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  20. Efficient Amide Based Halogenide Anion Receptors

    Institute of Scientific and Technical Information of China (English)

    Hong Xing WU; Feng Hua LI; Hai LIN; Shou Rong ZHU; Hua Kuan LIN

    2005-01-01

    In this paper, we present the synthesis and anion recognition properties of the amide based phenanthroline derivatives 1, 2 and 3. In all cases 1:1 receptor: anion complexes were observed. The receptors were found to be selective for fluoride and chloride respectively over other putative anionic guest species.

  1. Anion Solvation in Carbonate Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhengcheng

    2015-11-16

    With the correlation between Li+ solvation and interphasial chemistry on anodes firmly established in Li-ion batteries, the effect of cation–solvent interaction has gone beyond bulk thermodynamic and transport properties and become an essential element that determines the reversibility of electrochemistry and kinetics of Li-ion intercalation chemistries. As of now, most studies are dedicated to the solvation of Li+, and the solvation of anions in carbonate-based electrolytes and its possible effect on the electrochemical stability of such electrolytes remains little understood. As a mirror effort to prior Li+ solvation studies, this work focuses on the interactions between carbonate-based solvents and two anions (hexafluorophosphate, PF6–, and tetrafluoroborate, BF4–) that are most frequently used in Li-ion batteries. The possible correlation between such interaction and the interphasial chemistry on cathode surface is also explored.

  2. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

    Zhu, Zhiyuan; González, Yamaira I; Xu, Hangxun; Kaler, Eric W; Liu, Shiyong

    2006-01-31

    Polymerizable anionic wormlike micelles are obtained upon mixing the hydrotropic salt p-toluidine hydrochloride (PTHC) with the reactive anionic surfactant sodium 4-(8-methacryloyloxyoctyl)oxybenzene sulfonate (MOBS). Polymerization captures the cross-sectional radius of the micelles (approximately 2 nm), induces micellar growth, and leads to the formation of a stable single-phase dispersion of wormlike micellar polymers. The unpolymerized and polymerized micelles were characterized using static and dynamic laser light scattering, small-angle neutron scattering, 1H NMR, and stopped-flow light scattering. Stopped-flow light scattering was also used to measure the average lifetime of the unpolymerized wormlike micelles. A comparison of the average lifetime of unpolymerized wormlike micelles with the surfactant monomer propagation rate was used to elucidate the mechanism of polymerization. There is a significant correlation between the ratio of the average lifetime to the monomer propagation rate and the average aggregation number of the polymerized wormlike micelles. PMID:16430253

  3. Laser Cooling of Molecular Anions

    CERN Document Server

    Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-01-01

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.

  4. Anion-induced urea deprotonation.

    Science.gov (United States)

    Boiocchi, Massimo; Del Boca, Laura; Esteban-Gómez, David; Fabbrizzi, Luigi; Licchelli, Maurizio; Monzani, Enrico

    2005-05-01

    The urea-based receptor 1 (1-(7-nitrobenzo[1,2,5]oxadiazol-4-yl)-3-(4-nitrophenyl)urea, L--H), interacts with X- ions in MeCN, according to two consecutive steps: 1) formation of a hydrogen-bond complex [L--H...X]-; 2) deprotonation of L--H to give L- and [HX2]-, as shown by spectrophotometric and 1H NMR titration experiments. Step 2) takes place with more basic anions (fluoride, carboxylates, dihydrogenphosphate), while less basic anions (Cl-, NO2-, NO3-) do not induce proton transfer. On crystallisation from a solution containing L--H and excess Bu4NF, the tetrabutylammonium salt of the deprotonated urea derivative (Bu4N[L]) was isolated and its crystal and molecular structure determined. PMID:15770711

  5. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

    . Its characterization is investigated by Fourier Transform Infrared Spectroscopy (FT-IR and Scanning Electron Microscopy (SEM. The hybrid material presents predominantly high electronic conductivities of around 2.0 and 7.0 S cm-1 at 300 and 400K respectively.

  6. Environmental behavior of inorganic anions

    International Nuclear Information System (INIS)

    Recent efforts have addressed two aspects of anion behavior in the soil/plant system. The first involves evaluation of the gaseous component of the terrestrial iodine cycle in soils and plants. Field analyses of 129I in soils and vegetation adjacent to a fuels reprocessing facility, which was idle for 10 years prior to the study, indicated that there may be a significant gaseous component to the terrestrial iodine cycle. Soil substrates, including a silt-sand, organic forest soil, quartz sand, and a sterilized soil, were amended with radioiodide, and the rates and quality of the volatile components evaluated

  7. Adsorption affinity of anions on metal oxyhydroxides

    Science.gov (United States)

    Pechenyuk, S. I.; Semushina, Yu. P.; Kuz'mich, L. F.

    2013-03-01

    The dependences of anion (phosphate, carbonate, sulfate, chromate, oxalate, tartrate, and citrate) adsorption affinity anions from geometric characteristics, acid-base properties, and complex forming ability are generalized. It is shown that adsorption depends on the nature of both the anions and the ionic medium and adsorbent. It is established that anions are generally grouped into the following series of adsorption affinity reduction: PO{4/3-}, CO{3/2-} > C2O{4/2-}, C(OH)(CH2)2(COO){3/3-}, (CHOH)2(COO){2/2-} > CrO{4/2-} ≫ SO{4/2-}.

  8. Ursodeoxycholic acid and superoxide anion

    Institute of Scientific and Technical Information of China (English)

    Predrag Ljubuncic; Omar Abu-Salach; Arieh Bomzon

    2005-01-01

    AIM: To investigate the ability of ursodeoxycholic acid (UDCA) to scavenge superoxide anion (O2-).METHODS: We assessed the ability of UDCA to scavenge (O2-) generated by xanthine-xanthine oxidase (X-XO) in a cell-free system and its effect on the rate of O2--induced ascorbic acid (AA) oxidation in hepatic post-mitochondrial supernatants.RESULTS: UDCA at a concentration as high as 1 mmol/Ldid not impair the ability of the X-XO system to generate O2-, but could scavenge O2- at concentrations of 0.5 and 1 mmol/L, and decrease the rate of AA oxidation at a concentration of 100 μmol/L.CONCLUSION: UDCA can scavenge O2-, an action that may be beneficial to patients with primary biliary cirrhosis.

  9. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.;

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M alk...

  10. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  11. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  12. Counterintuitive interaction of anions with benzene derivatives

    Science.gov (United States)

    Quiñonero, David; Garau, Carolina; Frontera, Antonio; Ballester, Pau; Costa, Antonio; Deyà, Pere M.

    2002-06-01

    Ab initio calculations were carried out on complexes between 1,3,5-trinitrobenzene (TNB) and anions, where the anion is positioned over the ring along the C3 axis. This study combines crystallographic and computational evidences to demonstrate an attractive interaction between the anion and the π-cloud of TNB. This interaction is rationalized based on the important role of the quadrupole moment of TNB and the anion-induced polarization. In addition, this study has been extended to 1,3,5-trifluorobenzene (TFB), which possesses a very small quadrupole moment. As a result, minimum energy complexes have been found between TFB and both anions and cations due to the stabilization obtained from the ion-induced polarization.

  13. Molecular physiology of EAAT anion channels.

    Science.gov (United States)

    Fahlke, Christoph; Kortzak, Daniel; Machtens, Jan-Philipp

    2016-03-01

    Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. After release from presynaptic nerve terminals, glutamate is quickly removed from the synaptic cleft by a family of five glutamate transporters, the so-called excitatory amino acid transporters (EAAT1-5). EAATs are prototypic members of the growing number of dual-function transport proteins: they are not only glutamate transporters, but also anion channels. Whereas the mechanisms underlying secondary active glutamate transport are well understood at the functional and at the structural level, mechanisms and cellular roles of EAAT anion conduction have remained elusive for many years. Recently, molecular dynamics simulations combined with simulation-guided mutagenesis and experimental analysis identified a novel anion-conducting conformation, which accounts for all experimental data on EAAT anion currents reported so far. We here review recent findings on how EAATs accommodate a transporter and a channel in one single protein. PMID:26687113

  14. Renal elimination of organic anions in cholestasis

    Institute of Scientific and Technical Information of China (English)

    Adriana Mónica Tortes

    2008-01-01

    The disposition of most drugs is highly dependent on specialized transporters.OAT1 and OAT3 are two organic anion transporters expressed in the basolateral membrane of renal proximal tubule cells,identified as contributors to xenobiotic and endogenous organic anion secretion.It is well known that cholestasis may cause renal damage.Impairment of kidney function produces modifications in the renal elimination of drugs.Recent studies have demonstrated that the renal abundance of OAT1 and OAT3 plays an important role in the renal elimination of organic anions in the presence of extrahepatic cholestasis.Time elapsed after obstructive cholestasis has an important impact on the regulation of both types of organic anion transporters.The renal expression of OAT1 and OAT3 should be taken into account in order to improve pharmacotherapeutic efficacy and to prevent drug toxicity during the onset of this hepatic disease.

  15. Novel pseudo-delocalized anions for lithium battery electrolytes.

    Science.gov (United States)

    Jónsson, Erlendur; Armand, Michel; Johansson, Patrik

    2012-05-01

    A novel anion concept of pseudo-delocalized anions, anions with distinct positive and negative charge regions, has been studied by a computer aided synthesis using DFT calculations. With the aim to find safer and better performing lithium salts for lithium battery electrolytes two factors have been evaluated: the cation-anion interaction strength via the dissociation reaction LiAn ⇌ Li(+) + An(-) and the anion oxidative stability via a vertical ionisation from anion to radical. Based on our computational results some of these anions have shown promise to perform well as lithium salts for modern lithium batteries and should be interesting synthetic targets for future research. PMID:22441354

  16. Studies of anions sorption on natural zeolites.

    Science.gov (United States)

    Barczyk, K; Mozgawa, W; Król, M

    2014-12-10

    This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. PMID:25002191

  17. Recognition of anions by protonated methylazacalixpyridines

    Institute of Scientific and Technical Information of China (English)

    Han-yuan GONG; De-xian WANG; Zhi-tang HUANG; Mei-xiang WANG

    2009-01-01

    Methylazacalixpyridines are a unique kind of macro-cyclic molecules that are able to self-regulate their conformations to best fit the guests. They had shown good recognition to both neutral molecules such as diols and fullerenes and cations. After protonation, the conformation of methylazacalixpyridines became more flexible and could serve as receptors for anions.In the solution, the protonated methylazacalix[2]pyri-dine[2]arene formed complexes with halides yield-ing biding constants of 79(mol/L)-1 for chloride,10 (mol/L)-1 for bromide, and 79 (mol/L)-1 for iodide,respectively. The crystal structures of the complexes between protonated methylazaealix[4]pyridine (MACP-4), methylazacalix[2]pyridine[2] arene (MACP-2-A-2), and iodide anion showed a multiple interaction mode including electrostatic attraction,hydrogen bonding, and anion-π interactions.

  18. Identification and characterization of anion binding sites in RNA

    Energy Technology Data Exchange (ETDEWEB)

    Kieft, Jeffrey S.; Chase, Elaine; Costantino, David A.; Golden, Barbara L. (Purdue); (Colorado)

    2010-05-24

    Although RNA molecules are highly negatively charged, anions have been observed bound to RNA in crystal structures. It has been proposed that anion binding sites found within isolated RNAs represent regions of the molecule that could be involved in intermolecular interactions, indicating potential contact points for negatively charged amino acids from proteins or phosphate groups from an RNA. Several types of anion binding sites have been cataloged based on available structures. However, currently there is no method for unambiguously assigning anions to crystallographic electron density, and this has precluded more detailed analysis of RNA-anion interaction motifs and their significance. We therefore soaked selenate into two different types of RNA crystals and used the anomalous signal from these anions to identify binding sites in these RNA molecules unambiguously. Examination of these sites and comparison with other suspected anion binding sites reveals features of anion binding motifs, and shows that selenate may be a useful tool for studying RNA-anion interactions.

  19. Electron Photodetachment from Aqueous Anions. III. Dynamics of Geminate Pairs Derived from Photoexcitation of Mono- vs. Poly- atomic Anions

    CERN Document Server

    Lian, R; Crowell, R A; Shkrob, I A; Chen, X; Bradforth, S E; Lian, Rui; Oulianov, Dmitri A.; Crowell, Robert A.; Shkrob, Ilya A.; Bradforth, Stephen E.

    2005-01-01

    Photostimulated electron detachment from aqueous inorganic anions is the simplest example of solvent-mediated electron transfer. Here we contrast the behavior of halide anions with that of small polyatomic anions, such as pseudohalide anions (e.g., HS-) and common polyvalent anions (e.g., SO32-). Geminate recombination dynamics of hydrated electrons generated by 200 nm photoexcitation of aqueous anions (I-, Br-, OH-, HS-, CNS-, CO32-, SO32-, and Fe(CN)64-) have been studied. Prompt quantum yields for the formation of solvated, thermalized electrons and quantum yields for free electrons were determined. Pump-probe kinetics for 200 nm photoexcitation were compared with kinetics obtained at lower photoexcitation energy (225 nm or 242 nm) for the same anions, where possible. Free diffusion and mean force potential models of geminate recombination dynamics were used to analyze these kinetics. These analyses suggest that for polyatomic anions (including all polyvalent anions studied) the initial electron distributi...

  20. Photoelectron spectroscopy and theoretical studies of anion-π interactions: binding strength and anion specificity.

    Science.gov (United States)

    Zhang, Jian; Zhou, Bin; Sun, Zhen-Rong; Wang, Xue-Bin

    2015-02-01

    Proposed in theory and then their existence confirmed, anion-π interactions have been recognized as new and important non-covalent binding forces. Despite extensive theoretical studies, numerous crystal structural identifications, and a plethora of solution phase investigations, anion-π interaction strengths that are free from complications of condensed-phase environments have not been directly measured in the gas phase. Herein we present a joint photoelectron spectroscopic and theoretical study on this subject, in which tetraoxacalix[2]arene[2]triazine 1, an electron-deficient and cavity self-tunable macrocyclic, was used as a charge-neutral molecular host to probe its interactions with a series of anions with distinctly different shapes and charge states (spherical halides Cl(-), Br(-), I(-), linear thiocyanate SCN(-), trigonal planar nitrate NO3(-), pyramidic iodate IO3(-), and tetrahedral sulfate SO4(2-)). The binding energies of the resultant gaseous 1 : 1 complexes (1·Cl(-), 1·Br(-), 1·I(-), 1·SCN(-), 1·NO3(-), 1·IO3(-) and 1·SO4(2-)) were directly measured experimentally, exhibiting substantial non-covalent interactions with pronounced anion-specific effects. The binding strengths of Cl(-), NO3(-), IO3(-) with 1 are found to be strongest among all singly charged anions, amounting to ca. 30 kcal mol(-1), but only about 40% of that between 1 and SO4(2-). Quantum chemical calculations reveal that all the anions reside in the center of the cavity of 1 with an anion-π binding motif in the complexes' optimized structures, where 1 is seen to be able to self-regulate its cavity structure to accommodate anions of different geometries and three-dimensional shapes. Electron density surface and charge distribution analyses further support anion-π binding formation. The calculated binding energies of the anions and 1 nicely reproduce the experimentally estimated electron binding energy increase. This work illustrates that size-selective photoelectron

  1. Donnan Membrane Technique (DMT) for Anion Measurement

    NARCIS (Netherlands)

    Alonso Vega, M.F.; Weng, L.P.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

    2010-01-01

    Donnan membrane technique (DMT) is developed and tested for determination of free anion concentrations. Time needed to reach the Donnan membrane equilibrium depends on type of ions and the background. The Donnan membrane equilibrium is reached in 1 day for Cl-, 1-2 days for NO3-, 1-4 days for SO42-

  2. Anionic/cationic complexes in hair care.

    Science.gov (United States)

    O'Lenick, Tony

    2011-01-01

    The formulation of cosmetic products is always more complicated than studying the individual components in aqueous solution. This is because there are numerous interactions between the components, which make the formulation truly more than the sum of the parts. This article will look at interactions between anionic and cationic surfactants and offer insights into how to use these interactions advantageously in making formulations.

  3. Synthesis of azaphenanthridines via anionic ring closure

    DEFF Research Database (Denmark)

    Hansen, Henriette Møller; Lysén, M.; Begtrup, M.;

    2005-01-01

    A new and convergent synthesis of azaphenanthridines via an anionic ring closure is reported. Ortho-lithiation/in situ borylation of cyanopyridines produces the corresponding cyanopyridylboronic esters, which undergo a Suzuki-Miyaura cross-coupling to give the key intermediates. Addition of lithi...

  4. Two independent anion transport systems in rabbit mandibular salivary glands

    DEFF Research Database (Denmark)

    Novak, I; Young, J A

    1986-01-01

    Cholinergically stimulated Cl and HCO3 transport in perfused rabbit mandibular glands has been studied with extracellular anion substitution and administration of transport inhibitors. In glands perfused with HCO3-free solutions, replacement of Cl with other anions supported secretion...

  5. Understanding and modeling removal of anionic organic contaminants (AOCs) by anion exchange resins.

    Science.gov (United States)

    Zhang, Huichun; Shields, Anthony J; Jadbabaei, Nastaran; Nelson, Maurice; Pan, Bingjun; Suri, Rominder P S

    2014-07-01

    Ionic organic contaminants (OCs) are a growing concern for water treatment and the environment and are removed inefficiently by many existing technologies. This study examined removal of anionic OCs by anion exchange resins (AXRs) as a promising alternative. Results indicate that two polystyrene AXRs (IRA910 and IRA96) have higher sorption capacities and selectivity than a polyacrylate resin (A860). For the polystyrene resins, selectivity follows: phenolates ≥ aromatic dicarboxylates > aromatic monocarboxylates > benzenesulfonate > aliphatic carboxylates. This trend can be explained based on hydration energy, the number of exchange groups, and aromaticity and hydrophobicity of the nonpolar moiety (NPM) of the anions. For A860, selectivity only varies within a narrow range (0.13-1.64). Despite the importance of the NPM of the anions, neutral solutes were sorbed much less, indicating synergistic combinations of electrostatic and nonelectrostatic interactions in the overall sorption. By conducting multiple linear regression between Abraham's descriptors and nature log of selectivity, induced dipole-related interactions and electrostatic interactions were found to be the most important interaction forces for sorption of the anions, while solute H-bond basicity has a negative effect. A predictive model was then developed for carboxylates and phenolates based on the poly parameter linear free energy relationships established for a diverse range of 16 anions and 5 neutral solutes, and was validated by accurate prediction of sorption of five test solutes within a wide range of equilibrium concentrations and that of benzoate at different pH. PMID:24877792

  6. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    Energy Technology Data Exchange (ETDEWEB)

    Jonathan L. Sessler

    2007-09-21

    The major thrust of this project, led by the University of Kansas (Prof. Kristin Bowman-James), entails an exploration of the basic determinants of anion recognition and their application to the design, synthesis, and testing of novel sulfate extractants. A key scientific inspiration for the work comes from the need, codified in simple-to-appreciate terms by the Oak Ridge National Laboratory component of the team (viz. Dr. Bruce Moyer), for chemical entities that can help in the extractive removal of species that have low solubilities in borosilicate glass. Among such species, sulfate anion, has been identified as particularly insidious. Its presence interferes with the vitrification process, thus rendering the remediation of tank waste from, e.g., the Hanford site far more difficult and expensive. The availability of effective extractants, that would allow for the separation of separating sulfate from the major competing anions in the waste, especially nitrate, could allow for pre-vitrification removal of sulfate via liquid-liquid extraction. The efforts at The University of Texas, the subject of this report, have thus concentrated on the development of new sulfate receptors. These systems are designed to increase our basic understanding of anion recognition events and set the stage for the development of viable sulfate anion extractants. In conjunction with the Oak Ridge National Laboratory (ORNL) members of the research team, several of these new receptors were studied as putative extractants, with two of the systems being shown to act as promising synergists for anion exchange.

  7. Reversible photochromism of an N-salicylidene aniline anion.

    Science.gov (United States)

    Jacquemin, Pierre-Loïc; Robeyns, Koen; Devillers, Michel; Garcia, Yann

    2014-01-21

    The first N-salicylidene aniline anion showing reversible solid state thermochromic and photochromic properties is described. The photo-isomerization involves a trans-keto form which is stabilized thanks to the local anion surrounding. This photochromic anion can be used as a guest for the preparation of hybrid materials by insertion into a cationic host matrix. PMID:24022381

  8. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R.

    1999-12-16

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying {sup 2}{Sigma} and {sup 2}{Pi} states of C{sub 2n}H (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C{sub 2}H and C{sub 4}H. Other radicals studied include NCN and I{sub 3}. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I{sub 3} revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  9. Specific anion effects in Artemia salina.

    Science.gov (United States)

    Lo Nostro, Pierandrea; Ninham, Barry W; Carretti, Emiliano; Dei, Luigi; Baglioni, Piero

    2015-09-01

    The specific anion effect on the vitality of Artemia salina was investigated by measuring the Lethal Time LT50 of the crustaceans in the presence of different sodium salts solutions at room temperature and at the same ionic strength as natural seawater. Fluoride, thiocyanate and perchlorate are the most toxic agents, while chloride, bromide and sulfate are well tolerated. The rates of oxygen consumption of brine shrimps were recorded in mixed NaCl+NaF or NaCl+NaSCN solutions as a function of time. The results are discussed in terms of the Hofmeister series, and suggest that, besides the biochemical processes that involve F(-), SCN(-) and ClO4(-), the different physico-chemical properties of the strong kosmotropic and chaotropic anions may contribute in determining their strong toxicity for A. salina. PMID:25978674

  10. Gas-Phase Reactivity of Microsolvated Anions

    DEFF Research Database (Denmark)

    Thomsen, Ditte Linde

    Gas-phase studies of ion-molecule reactions shed light on the intrinsic factors that govern reactivity; and even solvent effects can be examined in the gasphase environment by employing microsolvated ions. An area that has received considerable attention with regard to the interplay between intri...... cannot be expected to catalyze hydrogen abstraction reactions by the hydroxyl radical under atmospherically relevant conditions....... from the solvent to the anion, resulting in a HO−(HOOH) rather than a HOO−(H2O) structure. However, the results demonstrate that the reactive nucleophile is nonetheless the HOO− anion. Finally, microsolvation applied to radical-molecule reactions allows us to demonstrate that a single water molecule......Gas-phase studies of ion-molecule reactions shed light on the intrinsic factors that govern reactivity; and even solvent effects can be examined in the gasphase environment by employing microsolvated ions. An area that has received considerable attention with regard to the interplay between...

  11. Politseiuuringud kooskõlastamisele / Liivia Anion

    Index Scriptorium Estoniae

    Anion, Liivia

    2003-01-01

    1. aprillil 2003. a. moodustatud uurimistööde kooskõlastamise komisjoni tegevuse eesmärk on saada ülevaade kõrgkoolides õppivate töötajate poolt politseis korraldatavatest uurimustest, kasutada saadud infot politsei kasuks ja vältida teenistujate tööd segavate uurimuste tegemist. Komisjoni liige Liivia Anion teeb ülevaate komisjoni otsustuspädevuse valdkondadest ja töökorraldusest

  12. Lowest autodetachment state of the water anion

    Science.gov (United States)

    Houfek, Karel; Čížek, Martin

    2016-05-01

    The potential energy surface of the ground state of the water anion H2O- is carefully mapped using multireference CI calculations for a large range of molecular geometries. Particular attention is paid to a consistent description of both the O-+H2 and OH-+H asymptotes and to a relative position of the anion energy to the ground state energy of the neutral molecule. The autodetachment region, where the anion state crosses to the electronic continuum is identified. The local minimum in the direction of the O- + H2 channel previously reported by Werner et al. [J. Chem. Phys. 87, 2913 (1987)] is found to be slighly off the linear geometry and is separated by a saddle from the autodetachment region. The autodetachment region is directly accessible from the OH-+H asymptote. For the molecular geometries in the autodetachment region and in its vicinity we also performed fixed-nuclei electron-molecule scattering calculations using the R-matrix method. Tuning of consistency of a description of the correlation energy in both the multireference CI and R-matrix calculations is discussed. Two models of the correlation energy within the R-matrix method that are consistent with the quantum chemistry calculations are found. Both models yield scattering quantities in a close agreement. The results of this work will allow a consistent formulation of the nonlocal resonance model of the water anion in a future publication. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  13. Donnan membrane technique (DMT) for anion measurement.

    Science.gov (United States)

    Vega, Flora Alonso; Weng, Liping; Temminghoff, Erwin J M; Van Riemsdijk, Willem H

    2010-04-01

    Donnan membrane technique (DMT) is developed and tested for determination of free anion concentrations. Time needed to reach the Donnan membrane equilibrium depends on type of ions and the background. The Donnan membrane equilibrium is reached in 1 day for Cl(-), 1-2 days for NO(3)(-), 1-4 days for SO(4)(2-) and SeO(4)(2-), and 1-14 days for H(2)PO(4)(-) in a background of 2-200 mM KCl or K(2)SO(4). The strongest effect of ionic strength on equilibrium time is found for H(2)PO(4)(-), followed by SO(4)(2-) and SeO(4)(2-), and then by Cl(-) and NO(3)(-). The negatively charged organic particles of fulvic and humic acids do not pass the membrane. Two approaches for the measurement of different anion species of the same element, such as SeO(4)(2-) and HSeO(3)(-), using DMT are proposed and tested. These two approaches are based on transport kinetics or response to ionic strength difference. A transport model that was developed previously for cation DMT is applied in this work to analyze the rate-limiting step in the anion DMT. In the absence of mobile/labile complexes, transport tends to be controlled by diffusion in solution at a low ionic strength, whereas at a higher ionic strength, diffusion in the membrane starts to control the transport.

  14. Several hemicyanine dyes as fluorescence chemosensors for cyanide anions

    Science.gov (United States)

    Liang, Muhan; Wang, Kangnan; Guan, Ruifang; Liu, Zhiqiang; Cao, Duxia; Wu, Qianqian; Shan, Yanyan; Xu, Yongxiao

    2016-05-01

    Four hemicyanine dyes as chemosensors for cyanide anions were synthesized easily. Their photophysical properties and recognition properties for cyanide anions were investigated. The results indicate that all the dyes can recognize cyanide anions with obvious color, absorption and fluorescence change. The recognition mechanism analysis basing on in situ 1H NMR and Job plot data indicates that to the compounds with hydroxyl group, the recognition mechanism is intramolecular hydrogen bonding interaction. However, to the compounds without hydroxyl group, cyanide anion is bonded to carbon-carbon double bond in conjugated bridge and induces N+ CH3 to neutral NCH3. Fluorescence of the compounds is almost quenched upon the addition of cyanide anions.

  15. Anionic complexes of Cu(I) with the closo-decaborate anion

    International Nuclear Information System (INIS)

    General procedures for synthesis of anionic Cu(I) complexes with the closo-decaborate anion were worked out; they make it possible to prepare coordination compounds with a wide set of organic cations. The interaction of onium closo-decaborates with [Cu2B10H10] in acetonitrile acidified with anhydrous trifluoroacetic acid was found to be the most effective synthetic method that secures high yield and quality of the obtained products. The structure of {(C2H5)3NH[CuB10H10]} was determined by X-ray diffraction analysis

  16. Anion-exchange chromatography of phosphopeptides: weak anion exchange versus strong anion exchange and anion-exchange chromatography versus electrostatic repulsion-hydrophilic interaction chromatography.

    Science.gov (United States)

    Alpert, Andrew J; Hudecz, Otto; Mechtler, Karl

    2015-01-01

    Most phosphoproteomics experiments rely on prefractionation of tryptic digests before online liquid chromatography-mass spectrometry. This study compares the potential and limitations of electrostatic repulsion-hydrophilic interaction chromatography (ERLIC) and anion-exchange chromatography (AEX). At a pH higher than 5, phosphopeptides have two negative charges per residue and are well-retained in AEX. However, peptides with one or two phosphate groups are not separated from peptides with multiple Asp or Glu residues, interfering with the identification of phosphopeptides. At a pH of 2, phosphate residues have just a single negative charge but Asp and Glu are uncharged. This facilitates the separation of phosphopeptides from unmodified acidic peptides. Singly phosphorylated peptides are retained weakly under these conditions, due to electrostatic repulsion, unless hydrophilic interaction is superimposed in the ERLIC mode. Weak anion-exchange (WAX) and strong anion-exchange (SAX) columns were compared, with both peptide standards and a HeLa cell tryptic digest. The SAX column exhibited greater retention at pH 6 than did the WAX column. However, only about 60% as many phosphopeptides were identified with SAX at pH 6 than via ERLIC at pH 2. In one ERLIC run, 12 467 phosphopeptides were identified, including 4233 with more than one phosphate. We conclude that chromatography of phosphopeptides is best performed at low pH in the ERLIC mode. Under those conditions, the performances of the SAX and WAX materials were comparable. The data have been deposited with the ProteomeXchange with identifier PXD001333. PMID:25827581

  17. Organic superconductors with an incommensurate anion structure

    Directory of Open Access Journals (Sweden)

    Tadashi Kawamoto and Kazuo Takimiya

    2009-01-01

    Full Text Available Superconducting incommensurate organic composite crystals based on the methylenedithio-tetraselenafulvalene (MDT-TSF series donors, where the energy band filling deviates from the usual 3/4-filled, are reviewed. The incommensurate anion potential reconstructs the Fermi surface for both (MDT-TSF(AuI20.436 and (MDT-ST(I30.417 neither by the fundamental anion periodicity q nor by 2q, but by 3q, where MDT-ST is 5H-2-(1,3-dithiol-2-ylidene-1,3-diselena-4,6-dithiapentalene, and q is the reciprocal lattice vector of the anion lattice. The selection rule of the reconstructing vectors is associated with the magnitude of the incommensurate potential. The considerably large interlayer transfer integral and three-dimensional superconducting properties are due to the direct donor–donor interactions coming from the characteristic corrugated conducting sheet structure. The materials with high superconducting transition temperature, Tc, have large ratios of the observed cyclotron masses to the bare ones, which indicates that the strength of the many-body effect is the major determinant of Tc. (MDT-TS(AuI20.441 shows a metal–insulator transition at TMI=50 K, where MDT-TS is 5H-2-(1,3-diselenol-2-ylidene-1,3,4,6-tetrathiapentalene, and the insulating phase is an antiferromagnet with a high Néel temperature (TN=50 K and a high spin–flop field (Bsf=6.9 T. There is a possibility that this material is an incommensurate Mott insulator. Hydrostatic pressure suppresses the insulating state and induces superconductivity at Tc=3.2 K above 1.05 GPa, where Tc rises to the maximum, Tcmax=4.9 K at 1.27 GPa. This compound shows a usual temperature–pressure phase diagram, in which the superconducting phase borders on the antiferromagnetic insulating phase, despite the unusual band filling.

  18. On the electronic structure of fullerene anions

    Energy Technology Data Exchange (ETDEWEB)

    Bergomi, L.; Jolicoeur, T. (CEA Centre d' Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique)

    1994-02-03

    The authors study the electronic states of isolated fullerene anions C[sub 60][sup n-] (1 [<=] n [<=] 6) taking into account the effective interaction between electrons due to exchange of intramolecular phonons. If the vibronic coupling is strong enough such an effect may overwhelm Hund's rule and lead to an ordering of levels that can be interpreted as on-ball pairing, in a manner similar to the pairing in atomic nuclei. The authors suggest that such effects may be sought in solutions of fulleride ions and discuss recent experimental results.

  19. Monocarbaborane anion chemistry. [COOH], [CH2OH] and [CHO] units as functional groups on ten-vertex monocarbaborane anionic compounds.

    Science.gov (United States)

    Franken, Andreas; Carr, Michael J; Clegg, William; Kilner, Colin A; Kennedy, John D

    2004-11-01

    B(10)H(14) reacts with para-C(6)H(4)(CHO)(COOH) in aqueous KOH solution to give the [nido-6-CB(9)H(11)-6-(C(6)H(4)-para-COOH)](-) anion 1, which undergoes cage closure with iodine in alkaline solution to give the [closo-2-CB(9)H(9)-2-(C(6)H(4)-para-COOH)](-) anion 2. Upon heating, anion 2 rearranges to form the [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-COOH)](-) anion 3. Similarly, B(10)H(14) with glyoxylic acid OHCCOOH in aqueous KOH gives the [arachno-6-CB(9)H(13)-6-(COOH)](-) anion 4, which undergoes cage closure with iodine in alkaline solution to give the [closo-2-CB(9)H(9)-2-(COOH)](-) anion 5. Upon heating, anion 5 rearranges to give the [closo-1-CB(9)H(9)-1-(COOH)](-) anion 6. Reduction of the [COOH] anions 3 and 6 with diisobutylaluminium hydride gives the [CH(2)OH] hydroxy anions [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-CH(2)OH)](-) and [closo-1-CB(9)H(9)-1-(CH(2)OH)](-) 8 respectively. The [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-CH(2)OH)](-) anion 7 can also be made via isomerisation of the [closo-2-CB(9)H(9)-2-(C(6)H(4)-para-CH(2)OH)](-) anion 9, in turn obtained from the [nido-6-CB(9)H(11)-6-(C(6)H(4)-para-CH(2)OH)](-) anion 10, which is obtained from the reaction of B(10)H(14) with terephthaldicarboxaldehyde, C(6)H(4)-para-(CHO)(2), in aqueous KOH solution. Oxidation of the hydroxy anions 7 and 8 with pyridinium dichromate gives the aldehydic [closo-1-CB(9)H(9)-1-(C(6)H(4)-para-CHO)](-) anion 11 and the aldehydic [closo-1-CB(9)H(9)-1-(CHO)](-) anion 12 respectively, characterised as their 2,4-dinitrophenylhydrazone derivatives, the [closo-1-CB(9)H(9)-1-C(6)H(4)-para-CH=N-NHC(6)H(3)(NO(2))(2)](-) anion 13 and the [closo-1-CB(9)H(9)-1-CH=N-NHC(6)H(3)(NO(2))(2)](-) anion respectively.

  20. Perspective: Electrospray photoelectron spectroscopy: From multiply-charged anions to ultracold anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lai-Sheng, E-mail: Lai-Sheng-Wang@brown.edu [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)

    2015-07-28

    Electrospray ionization (ESI) has become an essential tool in chemical physics and physical chemistry for the production of novel molecular ions from solution samples for a variety of spectroscopic experiments. ESI was used to produce free multiply-charged anions (MCAs) for photoelectron spectroscopy (PES) in the late 1990 s, allowing many interesting properties of this class of exotic species to be investigated. Free MCAs are characterized by strong intramolecular Coulomb repulsions, which create a repulsive Coulomb barrier (RCB) for electron emission. The RCB endows many fascinating properties to MCAs, giving rise to meta-stable anions with negative electron binding energies. Recent development in the PES of MCAs includes photoelectron imaging to examine the influence of the RCB on the electron emission dynamics, pump-probe experiments to examine electron tunneling through the RCB, and isomer-specific experiments by coupling PES with ion mobility for biological MCAs. The development of a cryogenically cooled Paul trap has led to much better resolved PE spectra for MCAs by creating vibrationally cold anions from the room temperature ESI source. Recent advances in coupling the cryogenic Paul trap with PE imaging have allowed high-resolution PE spectra to be obtained for singly charged anions produced by ESI. In particular, the observation of dipole-bound excited states has made it possible to conduct vibrational autodetachment spectroscopy and resonant PES, which yield much richer vibrational spectroscopic information for dipolar free radicals than traditional PES.

  1. Photoelectron Spectroscopy and Theoretical Studies of Anion-pi Interactions: Binding Strength and Anion Specificity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian; Zhou, Bin; Sun, Zhenrong; Wang, Xue B.

    2015-01-01

    Proposed in theory and confirmed to exist, anion–π interactions have been recognized as new and important non-covalent binding forces. Despite extensive theoretical studies, numerous crystal structural identifications, and a plethora of solution phase investigations, intrinsic anion–π interaction strengths that are free from complications of condensed phases’ environments, have not been directly measured in the gas phase. Herein we present a joint photoelectron spectroscopic and theoretical study on this subject, in which tetraoxacalix[2]arene[2]triazine 1, an electron-deficient and cavity self-tunable macrocyclic was used as a charge-neutral molecular host to probe its interactions with a series of anions with distinctly different shapes and charge states (spherical halides Cl⁻, Br⁻, I⁻, linear thiocyanate SCN⁻, trigonal planar nitrate NO₃⁻, pyramidic iodate IO₃⁻, and tetrahedral sulfate SO₄²⁻). The binding energies of the resultant gaseous 1:1 complexes (1•Cl⁻,1•Br⁻, 1•I⁻, 1•SCN⁻, 1•NO₃⁻, 1•IO₃⁻ and 1•SO₄²⁻) were directly measured experimentally, exhibiting substantial non-covalent interactions with pronounced anion specific effects. The binding strengths of Cl⁻, NO₃⁻, IO₃⁻ with 1 are found to be strongest among all singly charged anions, amounting to ca. 30 kcal/mol, but only about 40% of that between 1 and SO₄²⁻. Quantum chemical calculations reveal that all anions reside in the center of the cavity of 1 with anion–π binding motif in the complexes’ optimized structures, where 1 is seen to be able to self-regulate its cavity structure to accommodate anions of different geometries and three-dimensional shapes. Electron density surface and natural bond orbital charge distribution analysis further support anion–π binding formation. The calculated binding energies of the anions and 1 nicely reproduce the experimentally estimated electron binding energy increase. This work

  2. Preorganized anion traps for exploiting anion-π interactions: an experimental and computational study.

    Science.gov (United States)

    Bretschneider, Anne; Andrada, Diego M; Dechert, Sebastian; Meyer, Steffen; Mata, Ricardo A; Meyer, Franc

    2013-12-01

    1,3-Bis(pentafluorophenyl-imino)isoindoline (A(F)) and 3,6-di-tert-butyl-1,8-bis(pentafluorophenyl)-9H-carbazole (B(F)) have been designed as preorganized anion receptors that exploit anion-π interactions, and their ability to bind chloride and bromide in various solvents has been evaluated. Both receptors A(F) and B(F) are neutral but provide a central NH hydrogen bond that directs the halide anion into a preorganized clamp of the two electron-deficient appended arenes. Crystal structures of host-guest complexes of A(F) with DMSO, Cl(-), or Br(-) (A(F):DMSO, A(F):Cl(-), and A(2)(F):Br(-)) reveal that in all cases the guest is located in the cleft between the perfluorinated flaps, but NMR spectroscopy shows a more complex situation in solution because of E,Z/Z,Z isomerism of the host. In the case of the more rigid receptor B(F), Job plots evidence 1:1 complex formation with Cl(-) and Br(-), and association constants up to 960 M(-1) have been determined depending on the solvent. Crystal structures of B(F) and B(F):DMSO visualize the distinct preorganization of the host for anion-π interactions. The reference compounds 1,3-bis(2-pyrimidylimino)isoindoline (A(N)) and 3,6-di-tert-butyl-1,8-diphenyl-9H-carbazole (B(H)), which lack the perfluorinated flaps, do not show any indication of anion binding under the same conditions. A detailed computational analysis of the receptors A(F) and B(F) and their host-guest complexes with Cl(-) or Br(-) was carried out to quantify the interactions in play. Local correlation methods were applied, allowing for a decomposition of the ring-anion interactions. The latter were found to contribute significantly to the stabilization of these complexes (about half of the total energy). Compounds A(F) and B(F) represent rare examples of neutral receptors that are well preorganized for exploiting anion-π interactions, and rare examples of receptors for which the individual contributions to the binding energy have been quantified. PMID

  3. Protein Camouflage: Supramolecular Anion Recognition by Ubiquitin.

    Science.gov (United States)

    Mallon, Madeleine; Dutt, Som; Schrader, Thomas; Crowley, Peter B

    2016-04-15

    Progress in the field of bio-supramolecular chemistry, the bottom-up assembly of protein-ligand systems, relies on a detailed knowledge of molecular recognition. To address this issue, we have characterised complex formation between human ubiquitin (HUb) and four supramolecular anions. The ligands were: pyrenetetrasulfonic acid (4PSA), p-sulfonato-calix[4]arene (SCLX4), bisphosphate tweezers (CLR01) and meso-tetrakis (4-sulfonatophenyl)porphyrin (TPPS), which vary in net charge, size, shape and hydrophobicity. All four ligands induced significant changes in the HSQC spectrum of HUb. Chemical shift perturbations and line-broadening effects were used to identify binding sites and to quantify affinities. Supporting data were obtained from docking simulations. It was found that these weakly interacting ligands bind to extensive surface patches on HUb. A comparison of the data suggests some general indicators for the protein-binding specificity of supramolecular anions. Differences in binding were observed between the cavity-containing and planar ligands. The former had a preference for the arginine-rich, flexible C terminus of HUb. PMID:26818656

  4. Porating anion-responsive copolymeric gels.

    Science.gov (United States)

    England, Dustin; Yan, Feng; Texter, John

    2013-09-24

    A polymerizable ionic liquid surfactant, 1-(11-acryloyloxyundecyl)-3-methylimidiazolium bromide (ILBr), was copolymerized with methyl methacrylate (MMA) in aqueous microemulsions at 30% (ILBr w/w) and various water to MMA ratios. The ternary phase diagram of the ILBr/MMA/water system was constructed at 25 and 60 °C. Homopolymers and copolymers of ILBr and MMA were produced by thermally initiated chain radical microemulsion polymerization at various compositions in bicontinuous and reverse microemulsion subdomains. Microemulsion polymerization reaction products varied from being gel-like to solid, and these materials were analyzed by thermal and scanning electron microscopy methods. Microemulsion polymerized materials were insoluble in all solvents tested, consistent with light cross-linking. Ion exchange between Br(-) and PF6(-) in these copolymeric materials resulted in the formation of open-cell porous structures in some of these materials, as was confirmed by scanning electron microscopy (SEM). Several compositions illustrate the capture of prepolymerization nanoscale structure by thermally initiated polymerization, expanding the domain of compositions exhibiting this feat and yet to be demonstrated in any other system. Regular cylindrical pores in interpenetrating ILBr-co-MMA and PMMA networks are produced by anion exchange in the absence of templates. A percolating cluster/bicontinuous transition is "captured" by SEM after using anion exchange to visualize the mixed cluster/pore morphology. Some design principles for achieving this capture and for obtaining stimuli responsive solvogels are articulated, and the importance of producing solvogels in capturing the nanoscale is highlighted. PMID:23968242

  5. Anions in laser-induced plasmas

    Science.gov (United States)

    Shabanov, S. V.; Gornushkin, I. B.

    2016-07-01

    The equation of state for plasmas containing negative atomic and molecular ions (anions) is modeled. The model is based on the assumption that all ionization processes and chemical reactions are at local thermal equilibrium and the Coulomb interaction in the plasma is described by the Debye-Hückel theory. In particular, the equation of state is obtained for plasmas containing the elements Ca, Cl, C, Si, N, and Ar. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules CaCl_2, CaCl, Cl_2, N_2, C_2, Si_2, CN, SiN, SiC, and their positive and negative ions. The model is applied to laser-induced plasmas (LIPs) by including the equation of state into a fluid dynamic numerical model based on the Navier-Stokes equations describing an expansion of LIP plumes into an ambient gas as a reactive viscous flow with radiative losses. In particular, the formation of anions Cl-, C-, Si-, {{Cl}}2^{ - }, {{Si}}2^{ - }, {{C}}2^{ - }, CN-, SiC-, and SiN- in LIPs is investigated in detail.

  6. Reversible photochromism of an N-salicylidene aniline anion

    OpenAIRE

    Jacquemin, Pierre-Loïc; Robeyns, Koen; Devillers, Michel; Garcia, Yann

    2014-01-01

    The first N-salicylidene aniline anion showing reversible solid state thermochromic and photochromic properties is described. The photo-isomerization involves a trans-keto form which is stabilized thanks to the local anion surrounding. This photochromic anion can be used as a guest for the preparation of hybrid materials by insertion into a cationic host matrix. © 2014 The Royal Society of Chemistry.

  7. Anion concurrence and anion selectivity in the sorption of radionuclides by organotones

    International Nuclear Information System (INIS)

    Some long-lived and radiologically important nuclear fission products, such as I-129 (half-life t1/2 = 1,6 . 107 a), Tc-99 (t1/2 = 2,1 . 105 a), and Se-79 (t1/2 = 6,5 . 104 a) are anionic in aqueous environments. This study focuses on the adsorption of such anions to organoclays and the understanding of the selectivity of the process. The organoclays used in this study were prepared from a bentonite (MX-80) and a vermiculite clay, and the cationic surfactants hexadcylpyridium, hexadecyltrimethylammonium, and benzethonium. Surfactant adsorption to the bentonite exceeds the cation exchange capacity of the clay, with the surplus positive charge being balanced by the co-adsorption of chloride. The interlayer distance of the bentonites is increased sufficiently to contain bi- and pseudotrimolecular structures of the surfactants. Adsorption experiments were carried out using the batch technique. Anion adsorption of iodide, perrhenate, selenite, nitrate, and sulphate is mainly due to ion exchange with chloride. As an additional adsorption mechanism, the incorporation of inorganic ion pairs into the interlayer space of the clay is proposed as a result of experiments showing differences in the adsorption levels of sodium and potassium iodide. Anion adsorption results show a clear selectivity of the organoclays, with the affinity sequence being: ReO-4 > I- > NO-3 > Cl- > SO2-4 > SeO2-3. This sequence corresponds to the sequence of increasing hydration energies of the anions, thus selectivity could be due to the process of minimization of free energy of the system. (orig.)

  8. Identification and characterization of anion binding sites in RNA.

    Science.gov (United States)

    Kieft, Jeffrey S; Chase, Elaine; Costantino, David A; Golden, Barbara L

    2010-06-01

    Although RNA molecules are highly negatively charged, anions have been observed bound to RNA in crystal structures. It has been proposed that anion binding sites found within isolated RNAs represent regions of the molecule that could be involved in intermolecular interactions, indicating potential contact points for negatively charged amino acids from proteins or phosphate groups from an RNA. Several types of anion binding sites have been cataloged based on available structures. However, currently there is no method for unambiguously assigning anions to crystallographic electron density, and this has precluded more detailed analysis of RNA-anion interaction motifs and their significance. We therefore soaked selenate into two different types of RNA crystals and used the anomalous signal from these anions to identify binding sites in these RNA molecules unambiguously. Examination of these sites and comparison with other suspected anion binding sites reveals features of anion binding motifs, and shows that selenate may be a useful tool for studying RNA-anion interactions. PMID:20410239

  9. Approach to the Patient With a Negative Anion Gap.

    Science.gov (United States)

    Emmett, Michael

    2016-01-01

    When anion gap calculation generates a very small or negative number, an explanation must be sought. Sporadic (nonreproducible) measurement errors and systematic (reproducible) laboratory errors must be considered. If an error is ruled out, 2 general possibilities exist. A true anion gap reduction can be generated by either reduced concentrations of unmeasured anions such as albumin or increased concentrations of unmeasured cations such as magnesium, calcium, or lithium. This teaching case describes a patient with aspirin (salicylate) poisoning whose anion gap was markedly reduced (-47 mEq/L). The discussion systematically reviews the possibilities and provides the explanation for this unusual laboratory result. PMID:26363848

  10. A colorimetric tetrathiafulvalene-calix 4 pyrrole anion sensor

    DEFF Research Database (Denmark)

    Nielsen, K. A.

    2012-01-01

    The interaction and colorimetric sensing properties of a tetrathiafulvalene substituted calix[4]pyrrole sensor with anions were investigated using H-1 NMR and absorption spectroscopic techniques. Visual color changes were observed upon addition of different anions (Cl-, Br-, CN-, and AcO-) to a s......The interaction and colorimetric sensing properties of a tetrathiafulvalene substituted calix[4]pyrrole sensor with anions were investigated using H-1 NMR and absorption spectroscopic techniques. Visual color changes were observed upon addition of different anions (Cl-, Br-, CN-, and Ac......O-) to a solution of the sensor. (C) 2012 Elsevier Ltd. All rights reserved....

  11. Aza-Bambusurils En Route to Anion Transporters.

    Science.gov (United States)

    Singh, Mandeep; Solel, Ephrath; Keinan, Ehud; Reany, Ofer

    2016-06-20

    Previous calculations of anion binding with various bambusuril analogs predicted that the replacement of oxygen by nitrogen atoms to produce semiaza-bambus[6]urils would award these new cavitands with multiple anion binding properties. This study validates the hypothesis by efficient synthesis, crystallography, thermogravimetric analysis and calorimetry. These unique host molecules are easily accessible from the corresponding semithio-bambusurils in a one-pot reaction, which converts a single anion receptor into a potential anion channel. Solid-state structures exhibit simultaneous accommodation of three anions, linearly positioned within the cavity along the main symmetry axis. The ability to hold anions at a short distance of about 4 Å is reminiscent of natural chloride channels in E. coli, which exhibit similar distances between their adjacent anion binding sites. The calculated transition-state energy for double-anion movement through the channel suggests that although these host-guest complexes are thermodynamically stable they enjoy high kinetic flexibility to render them efficient anion channels. PMID:27225332

  12. Aluminum Zintl anion moieties within sodium aluminum clusters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Ganteför, Gerd; Bowen, Kit H., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnöckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States); Lee, Mal-Soon; Jena, P. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kandalam, Anil K., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University of Pennsylvania, West Chester, Pennsylvania 19383 (United States); Kiran, Boggavarapu, E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)

    2014-02-07

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium–aluminum cluster anions, Na{sub m}Al{sub n}{sup −}, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.

  13. Anion channelrhodopsins for inhibitory cardiac optogenetics.

    Science.gov (United States)

    Govorunova, Elena G; Cunha, Shane R; Sineshchekov, Oleg A; Spudich, John L

    2016-01-01

    Optical control of the heart muscle is a promising strategy for cardiology because it is more specific than traditional electrical stimulation, and allows a higher temporal resolution than pharmacological interventions. Anion channelrhodopsins (ACRs) from cryptophyte algae expressed in cultured neonatal rat ventricular cardiomyocytes produced inhibitory currents at less than one-thousandth of the light intensity required by previously available optogenetic tools, such as the proton pump archaerhodopsin-3 (Arch). Because of their greater photocurrents, ACRs permitted complete inhibition of cardiomyocyte electrical activity under conditions in which Arch was inefficient. Most importantly, ACR expression allowed precisely controlled shortening of the action potential duration by switching on the light during its repolarization phase, which was not possible with previously used optogenetic tools. Optical shortening of cardiac action potentials may benefit pathophysiology research and the development of optogenetic treatments for cardiac disorders such as the long QT syndrome. PMID:27628215

  14. Structural evolution of small ruthenium cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Waldt, Eugen [Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany); Hehn, Anna-Sophia; Ahlrichs, Reinhart [Institute für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstrasse 12, 76128 Karlsruhe (Germany); Kappes, Manfred M.; Schooss, Detlef, E-mail: detlef.schooss@kit.edu [Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe (Germany); Institute für Physikalische Chemie, Karlsruher Institut für Technologie, Kaiserstrasse 12, 76128 Karlsruhe (Germany)

    2015-01-14

    The structures of ruthenium cluster anions have been investigated using a combination of trapped ion electron diffraction and density functional theory computations in the size range from eight to twenty atoms. In this size range, three different structural motifs are found: Ru{sub 8}{sup −}–Ru{sub 12}{sup −} have simple cubic structures, Ru{sub 13}{sup −}–Ru{sub 16}{sup −} form double layered hexagonal structures, and larger clusters form close packed motifs. For Ru{sub 17}{sup −}, we find hexagonal close packed stacking, whereas octahedral structures occur for Ru{sub 18}{sup −}–Ru{sub 20}{sup −}. Our calculations also predict simple cubic structures for the smaller clusters Ru{sub 4}{sup −}–Ru{sub 7}{sup −}, which were not accessible to electron diffraction measurements.

  15. Advanced polymer chemistry of organometallic anions

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlin, R.M.; Abney, K.D. [Los Alamos National Lab., NM (United States); Balaich, G.J.; Fino, S.A. [Air Force Academy, CO (United States)

    1997-11-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of the project was to prepare and characterize new polymers incorporating cobalt dicarbollide. Specific goals were to prepare polymerizable cobalt dicarbollide monomers using the nucleophilic substitution route discovered in laboratories and to establish the reaction conditions required to form polymers from these complexes. This one-year project resulted in two publications (in press), and provided the foundation for further investigations into polymer synthesis and characterization using cobalt dicarbollide and other metallocarboranes. Interest in synthesizing organometallic polymers containing the cobalt bis(dicarbollide) anion is motivated by their possible application as cation exchange materials for the remediation of cesium-137 and strontium-90 from nuclear wastes.

  16. Anion channelrhodopsins for inhibitory cardiac optogenetics

    Science.gov (United States)

    Govorunova, Elena G.; Cunha, Shane R.; Sineshchekov, Oleg A.; Spudich, John L.

    2016-01-01

    Optical control of the heart muscle is a promising strategy for cardiology because it is more specific than traditional electrical stimulation, and allows a higher temporal resolution than pharmacological interventions. Anion channelrhodopsins (ACRs) from cryptophyte algae expressed in cultured neonatal rat ventricular cardiomyocytes produced inhibitory currents at less than one-thousandth of the light intensity required by previously available optogenetic tools, such as the proton pump archaerhodopsin-3 (Arch). Because of their greater photocurrents, ACRs permitted complete inhibition of cardiomyocyte electrical activity under conditions in which Arch was inefficient. Most importantly, ACR expression allowed precisely controlled shortening of the action potential duration by switching on the light during its repolarization phase, which was not possible with previously used optogenetic tools. Optical shortening of cardiac action potentials may benefit pathophysiology research and the development of optogenetic treatments for cardiac disorders such as the long QT syndrome. PMID:27628215

  17. Protonation Reaction of Benzonitrile Radical Anion and Absorption of Product

    DEFF Research Database (Denmark)

    Holcman, Jerzy; Sehested, Knud

    1975-01-01

    The rate constant for the protonation of benzonitrile radical anions formed in pulse radiolysis of aqueous benzonitrile solutions is (3.5 ± 0.5)× 1010 dm3 mol–1 s–1. A new 270 nm absorption band is attributed to the protonated benzonitrile anion. The pK of the protonation reaction is determined...

  18. Diffuse neutron scattering from anion-excess strontium chloride

    DEFF Research Database (Denmark)

    Goff, J.P.; Clausen, K.N.; Fåk, B.;

    1992-01-01

    The defect structure and diffusional processes have been studied in the anion-excess fluorite (Sr, Y)Cl2.03 by diffuse neutron scattering techniques. Static cuboctahedral clusters found at ambient temperature break up at temperatures below 1050 K, where the anion disorder is highly dynamic. The...

  19. Triflyloxy-substituted carboranes as useful weakly coordinating anions.

    Science.gov (United States)

    Press, Loren P; McCulloch, Billy J; Gu, Weixing; Chen, Chun-Hsing; Foxman, Bruce M; Ozerov, Oleg V

    2015-09-25

    New carborane anions carrying one or three triflyloxy substituents are described. The mono-triflyloxy substituted carborane can be halogenated to give pentabromo and decachloro derivatives with preservation of the B-OTf linkage. The use of [HCB11Cl10OTf](-) as a weakly coordinating anion is demonstrated. PMID:26251850

  20. Anion binding by biotin[6]uril in water

    DEFF Research Database (Denmark)

    Lisbjerg, Micke; Nielsen, Bjarne Enrico; Milhøj, Birgitte Olai;

    2015-01-01

    In this contribution we show that the newly discovered 6 + 6 biotin-formaldehyde macrocycle Biotin[6]uril binds a variety of anionic guest molecules in water. We discuss how and why the anions are bound based on data obtained using NMR spectroscopy, mass spectrometry, isothermal titration...

  1. ARE MODELS OF ANION HYDRATION OVERBOUND ? THE SOLVATION OF THE ELECTRON AND CHLORIDE ANION COMPARED

    OpenAIRE

    Sprik, M.

    1991-01-01

    By means of a fully polarizable model for the chloride ion-water interaction we show that the modelling of anion solvation suffers from a similar inconsistency as the current electron-solvent potentials. Either the bulk hydration enthalpies are correct with the first hydration shell overbound, or the potential is adapted to describe the local environment of the solute at the expense of a major loss of solvation enthalpy. It is argued that boundary effects in the simulation are at least partly...

  2. Superoxide anion production by human neutrophils activated by Trichomonas vaginalis.

    Science.gov (United States)

    Song, Hyun-Ouk; Ryu, Jae-Sook

    2013-08-01

    Neutrophils are the predominant inflammatory cells found in vaginal discharges of patients infected with Trichomonas vaginalis. In this study, we examined superoxide anion (O2 (.-)) production by neutrophils activated by T. vaginalis. Human neutrophils produced superoxide anions when stimulated with either a lysate of T. vaginalis, its membrane component (MC), or excretory-secretory product (ESP). To assess the role of trichomonad protease in production of superoxide anions by neutrophils, T. vaginalis lysate, ESP, and MC were each pretreated with a protease inhibitor cocktail before incubation with neutrophils. Superoxide anion production was significantly decreased by this treatment. Trichomonad growth was inhibited by preincubation with supernatants of neutrophils incubated for 3 hr with T. vaginalis lysate. Furthermore, myeloperoxidase (MPO) production by neutrophils was stimulated by live trichomonads. These results indicate that the production of superoxide anions and MPO by neutrophils stimulated with T. vaginalis may be a part of defense mechanisms of neutrophils in trichomoniasis.

  3. Coumarin amide derivatives as fluorescence chemosensors for cyanide anions

    International Nuclear Information System (INIS)

    Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions have been examined. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change, at the same time, obvious color and fluorescence change can be observed by naked eye. The in situ hydrogen nuclear magnetic resonance spectra and photophysical properties change confirm that Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin. - Highlights: • Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group were synthesized. • The compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change. • Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin

  4. Coumarin amide derivatives as fluorescence chemosensors for cyanide anions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qianqian [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Liu, Zhiqiang [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, Shandong (China); Cao, Duxia, E-mail: duxiacao@ujn.edu.cn [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Guan, Ruifang, E-mail: mse_guanrf@ujn.edu.cn [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Wang, Kangnan; Shan, Yanyan; Xu, Yongxiao; Ma, Lin [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China)

    2015-07-01

    Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions have been examined. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change, at the same time, obvious color and fluorescence change can be observed by naked eye. The in situ hydrogen nuclear magnetic resonance spectra and photophysical properties change confirm that Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin. - Highlights: • Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group were synthesized. • The compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change. • Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin.

  5. An outwardly rectifying anionic background current in atrial myocytes from the human heart

    OpenAIRE

    Li, H.; Zhang, H.; Hancox, J C; Kozlowski, R. Z.

    2007-01-01

    This report describes a hitherto unreported anionic background current from human atrial cardiomyocytes. Under whole-cell patch-clamp with anion-selective conditions, an outwardly rectifying anion current (I ANION) was observed, which was larger with iodide than nitrate, and with nitrate than chloride as charge carrier. In contrast with a previously identified background anionic current from small mammal cardiomyocytes, I ANION was not augmented by the pyrethroid tefluthrin (10 μM); neither w...

  6. Designing New Electrolytes for Lithium Ion Batteries Using Superhalogen Anions

    CERN Document Server

    Srivastava, Ambrish Kumar

    2016-01-01

    The electrolytes used in Lithium Ion Batteries (LIBs) such as LiBF4, LiPF6 etc. are Li-salts of some complex anions, BF4-, PF6- etc. The investigation shows that the vertical detachment energy (VDE) of these anions exceeds to that of halogen, and therefore they behave as superhalogen anions. Consequently, it might be possible to design new electrolytic salts using other superhalogen anions. We have explored this possibility using Li-salts of various superhalogen anions such as BO2-, AlH4-, TiH5- and VH6- as well as hyperhalogen anions, BH4-y(BH4)y-(y = 1 to 4). Our density functional calculations show that Li-salts of these complex anions possess similar characteristics as those of electrolytic salts in LIBs. Note that they all are halogen free and hence, non-toxic and safer than LiBF4, LiPF6 etc. In particular, LiB4H13 and LiB5H16 are two potential candidates for electrolytic salt due to their smaller Li-dissociation energy ({\\Delta}E) than those of LiBF4, LiPF6 etc. We have also noticed that {\\Delta}E of Li...

  7. Pyruvate anions neutralize peritoneal dialysate cytotoxicity.

    Science.gov (United States)

    Mahiout, A; Brunkhorst, R

    1995-01-01

    A new peritoneal dialysate containing pyruvate anions was developed in order to avoid cytotoxic effect of conventional lactate-based dialysate. The dialysate has a final pH of 5.4 to 5.6 and is composed of 1.36-3.86% glucose-monohydrate; 132 mmol/l sodium; 1.75 mmol/l calcium; 0.75 mmol/l magnesium; 102 mmol/l chloride and 35 mmol/l pyruvate. For cytotoxicity testing peritoneal macrophages, and mesothelial cells (MC) were exposed to conventional lactate dialysate, and pyruvate dialysate. We investigated the O2- generation and cytokine synthesis after endotoxin stimulation in peritoneal macrophages and the proliferation of mesothelial cells of cultured human MC. After exposure to lactate dialysate O2- generation and cytokine synthesis in peritoneal macrophages and proliferation of mesothelial cells were inhibited when compared to solution containing pyruvate and the control solution. After preincubation with 3.86% glucose containing solutions, all negative effects became even more pronounced in the lactate group whereas after pre-exposure to pyruvate containing solution the toxic effects were absent. These results suggest that the acute toxic effects of commercially available peritoneal dialysates can be avoided by the use of sodium pyruvate instead of sodium lactate.

  8. Antimicrobial Ionic Liquids with Fumarate Anion

    Directory of Open Access Journals (Sweden)

    Biyan He

    2013-01-01

    Full Text Available The shortage of new antimicrobial drugs and increasing resistance of microbe to antimicrobial agents have been of some concern. The formulation studies of new antibacterial and antifungal agents have been an active research field. Ionic liquids are known as designed liquids with controllable physical/chemical/biological properties and specific functions, which have been attracting considerable interest over recent years. However, no attention has been made towards the preparation of ionic liquids with antimicrobial activities. In this paper, a new class of ionic liquids (ILs with fumarate anion was synthesized by neutralization of aqueous 1-butyl-3-methylimidazolium hydroxide with equimolar monoester fumarate and characterized using NMR and thermal gravimetric analysis. The ILs are soluble in water and polar organic solvents and also soluble in the common ILs. The antimicrobial activities of the ILs are more active than commercially available potassium sorbate and are greatly affected by the alkyl chain length. The significant antimicrobial properties observed in this research suggest that the ILs may have potential applications in the modern biotechnology.

  9. Survey of organic acid eluents for anion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Book, D.E.

    1981-10-01

    Of all the potential eluents surveyed (including aromatic, sulfonic, phosphonic, among other acids), only the carboxylic acids and the nitrophenols are recommended as eluents for anion chromatography. The concentration of the eluent should be in the range 5 x 10/sup -5/ to 1 x 10/sup -3/ M. The eluent should have the same charge as inorganic anions, a higher charge than organic acid samples. Choice of eluents for separation of halides, chloride and sulfate, multivalent inorganic anions, small alkyl acids, and aromatic acids is discussed. (DLC)

  10. Simultaneous determination of inorganic and organic anions by ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yang Soon; Joe, Ki Soo; Han, Sun Ho; Park, Soon Dal; Choi, Kwang Soon

    1999-06-01

    Four methods were investigated for the simultaneous determination of several inorganic and organic anions in aqueous solution by ion chromatography. The first is two columns coupled system. The second is the gradient elution system with an anion exchange column. The third is the system with a mixed-mode stationary phase. The fourth is the system with an anion exchange column and the eluant of low conductivity without ion suppressor. The advantages and disadvantages of individual systems were discussed. The suitable methods were proposed for the application to the samples of the nuclear power industry and the environment. (author)

  11. Metal ion separations using hydrophobic anions: Aspects of ligand design

    International Nuclear Information System (INIS)

    Metal ion extraction using hydrophobic anions has been investigated by several researchers for remediation of Cs-137 and Sr-90 in nuclear waste. The rich derivative chemistry of the cobalt bis-dicarbollide anion makes it amendable to systematic studies of the relative importance of anion structure, solvent, and synergists on the extraction selectivity and efficiency. Halogenation or alkylation of cobalt dicarbollide strongly influences the anion's solubility and stability but has little effect on extraction properties. Alkali metal selectivity depends primarily on solvent, while alkaline earth selectivity is driven by the concentration and molecular weight of polyethylene glycol synergists. Additional aspects of ligand design, including a simple extraction and recovery cycle based on redox-active metal centers, will be discussed

  12. Unmeasured anions and mortality in critically ill patients in 2016.

    Science.gov (United States)

    Kotake, Yoshifumi

    2016-01-01

    The presence of acid-base disturbances, especially metabolic acidosis may negatively affect the outcome of critically ill patients. Lactic acidosis is the most frequent etiology and has largest impact on the prognosis. Since lactate measurement might not have always been available at bedside, it had been regarded as one of the unmeasured anions. Therefore, anion gap and strong ion gap has been used to as a surrogate of lactate concentration. From this perspective, the relationship between either anion gap or strong ion gap and mortality has been explored. Then, lactate became routinely measurable at bedside and the direct comparison between directly measured lactate and these surrogate parameters can be possible. Currently available evidence suggests that directly measured lactate has larger prognostic ability for mortality than albumin-corrected anion gap and strong ion gap without lactate. In this commentary, the rationale and possible clinical implications of these findings are discussed. PMID:27429758

  13. Hydrocarbon anions in interstellar clouds and circumstellar envelopes

    CERN Document Server

    Millar, T J; Cordiner, M A; Herbst, Eric; Walsh, C

    2007-01-01

    The recent detection of the hydrocarbon anion C6H- in the interstellar medium has led us to investigate the synthesis of hydrocarbon anions in a variety of interstellar and circumstellar environments. We find that the anion/neutral abundance ratio can be quite large, on the order of at least a few percent, once the neutral has more than five carbon atoms. Detailed modeling shows that the column densities of C6H- observed in IRC+10216 and TMC-1 can be reproduced. Our calculations also predict that other hydrocarbon anions, such as C4H- and C8H-, are viable candidates for detection in IRC+10216, TMC-1 and photon-dominated regions such as the Horsehead Nebula.

  14. Migration of Cations and Anions in Amorphous Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    N.A.Stolwijk; S.H.Obeidi; M.Wiencierz

    2007-01-01

    1 Results Polymer electrolytes are used as ion conductors in batteries and fuel cells.Simple systems consist of a polymer matrix complexing an inorganic salt and are fully amorphous at the temperatures of interest.Both cations and anions are mobile and contribute to charge transport.Most studies on polymer electrolytes use the electrical conductivity to characterize the ion mobility.However,conductivity measurements cannot discriminate between cations and anions.This paper reports some recent results fr...

  15. Determination of nitrate by anion exchange with ultraviolet detection

    Energy Technology Data Exchange (ETDEWEB)

    McComas, J.G.

    1976-01-01

    A weak base anion exchange resin is synthesized by surface bonding 3-aminopropyltriethoxysilane to silica gel. This silylated silica gel is used to separate nitrate from interferences. The nitrate is then determined by measuring its absorbance at 220 nm. An interference study was performed and no anions commonly found in potable water interferes. A comparison of this method was made with the brucine method on real samples and satisfactory agreement was obtained between the two methods.

  16. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

  17. Synthesis and Binding Properties of Two New Artificial Anion Receptors

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhen-Ya; HUANG Yan-Yan; HU Ling; WANG Fa-Jun; HE Yong-Bing

    2003-01-01

    @@ The development of anion receptor has attracted increasing interest in supramolecular chemistry, due to poten tial applications in clinical diagnosis, environmental monitoring and biological process. [1] In comparison with thelarge variety of ligands that have been described for cations, [2] the development of selective artificial receptors foranion is still very limited. [3] Two new neutral anion receptors (1 and 2) containing thiourea and amide groups weresynthesized as shown in Scheme 1.

  18. Reaction of tungsten anion clusters with molecular and atomic nitrogen

    OpenAIRE

    Kim, Young Dok; Stolcic, Davor; Fischer, Matthias; Ganteför, Gerd

    2003-01-01

    Ultraviolet photoelectron spectra for WnN-2 (n=1 8) clusters produced by addition of atomic and molecular nitrogen on W anion clusters are presented. Evidence is provided that molecular chemisorption of N2 is more stable than the dissociative one on tungsten anion clusters consisting of eight atoms or less, which is completely different from the results on tungsten bulk surfaces. A general tendency toward molecular chemisorption for small clusters can be explained by reduced charge transfer f...

  19. GAS-GRAIN MODELS FOR INTERSTELLAR ANION CHEMISTRY

    International Nuclear Information System (INIS)

    Long-chain hydrocarbon anions CnH– (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with nH2∼>105 cm–3). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H– anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment.

  20. GAS-GRAIN MODELS FOR INTERSTELLAR ANION CHEMISTRY

    Energy Technology Data Exchange (ETDEWEB)

    Cordiner, M. A. [Also at Institute for Astrophysics and Computational Sciences, Catholic University of America, Washington, DC 20064 (United States); Charnley, S. B., E-mail: martin.cordiner@nasa.gov [Astrochemistry Laboratory and Goddard Center for Astrobiology, Mailstop 691, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20770 (United States)

    2012-04-20

    Long-chain hydrocarbon anions C{sub n}H{sup -} (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n{sub H{sub 2}}{approx}>10{sup 5} cm{sup -3}). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C{sub 6}H{sup -} anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C{sub 6}O, C{sub 7}O, HC{sub 6}O, and HC{sub 7}O, the abundances of which depend on the assumed branching ratios for associative electron detachment.

  1. Core-modified octaphyrins: Syntheses and anion-binding properties

    Indian Academy of Sciences (India)

    Rajneesh Misra; Venkataramanarao G Anand; Harapriya Rath; Tavarekere K Chandrashekar

    2005-03-01

    In this paper, a brief review of the syntheses, characterization and anion-binding properties of core-modified octaphyrins is presented. It has been shown that the core-modified octaphyrins exhibit aromaticity both in solution and in solid state, confirming the validity of the (4 + 2) Huckel rule for larger -electron systems. Solid-state binding characteristics of TFA anions of two core-modified octaphyrins are also described.

  2. Determination of trace inorganic anions in anionic surfactants by single-pump column-switching ion chromatography

    Institute of Scientific and Technical Information of China (English)

    Jia Jie Zhang; Hai Bao Zhu; Yan Zhu

    2012-01-01

    An ion chromatography method has been proposed for the determination of three common inorganic anions (chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits (S/N =3) were in the range of 0.10-0.68 μg/L.The relative standard deviations (RSDs)of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.

  3. DISCOVERY OF INTERSTELLAR ANIONS IN CEPHEUS AND AURIGA

    International Nuclear Information System (INIS)

    We report the detection of microwave emission lines from the hydrocarbon anion C6H- and its parent neutral C6H in the star-forming region L1251A (in Cepheus), and the pre-stellar core L1512 (in Auriga). The carbon-chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for L1512. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.

  4. REACTIVITY OF ANIONS IN INTERSTELLAR MEDIA: DETECTABILITY AND APPLICATIONS

    International Nuclear Information System (INIS)

    We propose a general rule to distinguish between detectable and undetectable astronomical anions. We believe that only few anions live long enough in the interstellar medium and thus can be detected. Our method is based on quantum mechanical calculations capable of describing accurately the evolution of electronic states during chemical processes. The still not fully understood reactivity at low temperatures is discussed considering non-adiabatic effects. The role of excited states has usually been neglected in previous works which basically focused on the ground electronic state for interpretations of experimental observations. Here, we deal with unsaturated carbon chains (e.g., Cn H–), which show a high density of electronic states close to their corresponding ground electronic states, complex molecular dynamics, and non-adiabatic phenomena. Our general rule shows that it is not sufficient that anions exist in the gas phase (in the laboratory) to be present in media such as astrophysical media, since formation and decomposition reactions of these anions may allow the population of anionic electronic states to autodetach, forming neutrals. For Cn H, reactivity depends strongly on n, where long and short chains behave differently. Formation of linear chains is relevant.

  5. Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

    Science.gov (United States)

    West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

    2007-01-01

    We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

  6. REACTIVITY OF ANIONS IN INTERSTELLAR MEDIA: DETECTABILITY AND APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Senent, M. L. [Departamento de Quimica y Fisica Teoricas, Instituto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid E-28006 (Spain); Hochlaf, M., E-mail: senent@iem.cfmac.csic.es, E-mail: hochlaf@univ-mlv.fr [Laboratoire de Modelisation et Simulation Multi Echelle, Universite Paris-Est, MSME UMR 8208 CNRS, 5 boulevard Descartes, F-77454 Marne-la-Vallee (France)

    2013-05-01

    We propose a general rule to distinguish between detectable and undetectable astronomical anions. We believe that only few anions live long enough in the interstellar medium and thus can be detected. Our method is based on quantum mechanical calculations capable of describing accurately the evolution of electronic states during chemical processes. The still not fully understood reactivity at low temperatures is discussed considering non-adiabatic effects. The role of excited states has usually been neglected in previous works which basically focused on the ground electronic state for interpretations of experimental observations. Here, we deal with unsaturated carbon chains (e.g., C{sub n} H{sup -}), which show a high density of electronic states close to their corresponding ground electronic states, complex molecular dynamics, and non-adiabatic phenomena. Our general rule shows that it is not sufficient that anions exist in the gas phase (in the laboratory) to be present in media such as astrophysical media, since formation and decomposition reactions of these anions may allow the population of anionic electronic states to autodetach, forming neutrals. For C{sub n} H, reactivity depends strongly on n, where long and short chains behave differently. Formation of linear chains is relevant.

  7. Cell wall bound anionic peroxidases from asparagus byproducts.

    Science.gov (United States)

    Jaramillo-Carmona, Sara; López, Sergio; Vazquez-Castilla, Sara; Jimenez-Araujo, Ana; Rodriguez-Arcos, Rocio; Guillen-Bejarano, Rafael

    2014-10-01

    Asparagus byproducts are a good source of cationic soluble peroxidases (CAP) useful for the bioremediation of phenol-contaminated wastewaters. In this study, cell wall bound peroxidases (POD) from the same byproducts have been purified and characterized. The covalent forms of POD represent >90% of the total cell wall bound POD. Isoelectric focusing showed that whereas the covalent fraction is constituted primarily by anionic isoenzymes, the ionic fraction is a mixture of anionic, neutral, and cationic isoenzymes. Covalently bound peroxidases were purified by means of ion exchange chromatography and affinity chromatography. In vitro detoxification studies showed that although CAP are more effective for the removal of 4-CP and 2,4-DCP, anionic asparagus peroxidase (AAP) is a better option for the removal of hydroxytyrosol (HT), the main phenol present in olive mill wastewaters.

  8. Analysis of anions in geological brines using ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Merrill, R.M.

    1985-03-01

    Ion chromatographic procedures for the determination of the anions bromide, sulfate, nitrite, nitrate, phosphate, and iodide in brine samples have been developed and are described. The techniques have been applied to the analysis of natural brines, and geologic evaporites. Sample matrices varied over a range from 15,000 mg/L to 200,000 mg/L total halogens, nearly all of which is chloride. The analyzed anion concentrations ranged from less than 5 mg/L in the cases of nitrite, nitrate, and phosphate, to 20,000 mg/L in the case of sulfate. A technique for suppressing chloride and sulfate ions to facilitate the analysis of lower concentration anions is presented. Analysis times are typically less than 20 minutes for each procedure and the ion chromatographic results compare well with those obtained using more time consuming classical chemical analyses. 10 references, 14 figures.

  9. Determination of arsenate in water by anion selective membrane electrode using polyurethane–silica gel fibrous anion exchanger composite

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Asif Ali, E-mail: asifkhan42003@yahoo.com; Shaheen, Shakeeba, E-mail: shakeebashaheen@ymail.com

    2014-01-15

    Highlights: • PU–Si gel is new anion exchanger material synthesized and characterized. • This material used as anion exchange membrane is applied for electroanalytical studies. • The method for detection and determination of AsO{sub 4}{sup 3−} in traces amounts discussed. • The results are also verified from arsenic analyzer. -- Abstract: Polyurethane (PU)–silica (Si gel) based fibrous anion exchanger composites were prepared by solid–gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU–Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1 × 10{sup −8} M to 1 × 10{sup −1} M), response time (45 s) and working pH range (5–8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO{sub 4}{sup 3−}) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

  10. Infrared Predissociation Spectroscopy of H_2-TAGGED Dicarboxylic Acid Anions

    Science.gov (United States)

    Wolk, Arron B.; Kamrath, Michael Z.; Leavitt, Christopher M.; Johnson, Mark A.

    2011-06-01

    Singly charged dicarboxylic acid anions, studied in depth by Wang et al. offer insight into the role of ring strain and conformation on the formation of intramolecular hydrogen bonds. These shared proton bonds, common in proteins and polymer systems, can be crucial in secondary and tertiary structure formation. By tracking the infrared spectra of dicarboxylic acid anions as charge and aliphatic chain length are varied, the tendency of these anions to form ring-like structures with an internally shared proton can be asssesed. To adapt the time-of-flight mass spectrometry/infrared presdissociation experiment to larger systems with significant latent vibrational energy and negligible vapor pressure, an electrospray ionization (ESI)/cryogenic quadrupole trap ion source has been interfaced to the Yale time of flight mass spectrometer. Infrared predissociation spectroscopy is carried out on a series of carboxylate anions cooled to 10K and H_2-tagged in a cryogenic ion trap, underscoring the power of this technique to vibrationally quench and structurally characterize large (> 20 atoms) gaseous ions. This technique recovers sharp transitions (~6 cm^-^1 FWHM) in the linear single photon absorption regime which greatly facilitates comparison with ab initio calculations. The methodology used to condense H_2 on these ions is described, revealing the benefits of a pulsed trapping gas paired with a time delay before ion extraction. The sensitivity of the perturbed H_2 transition to charge center exposure is probed by varying the charge and aliphatic chain length of carboxylate anions. Finally, the structure of four carboxylate anions are characterized using their predissociation spectra. H. K. Woo, X. B. Wang, K. C. Lau and L. S. Wang J. Chem. Phys. A 110, 7801-7805 2006.

  11. The thiocyanate anion as a polydentate halogen bond acceptor

    OpenAIRE

    Cauliez, Pascal; Polo, Victor; Roisnel, Thierry; Llhusar, Rosa; Fourmigué, Marc

    2010-01-01

    International audience Co-crystallisation of the Et4N+ or n-Bu4N+ salts of the thiocyanate anion with o-, m- and p-diodoperfluorobenzene or the sym-trifluorotriiodobenzene allowed for the isolation of six different salts which were structurally characterized by single crystal X-ray diffraction. Halogen bonding interactions are observed between the neutral iodinated molecules acting as halogen bond donors and the S or N ends of the thiocyanate anion, with a variety of bonding modes (termina...

  12. Procedure for reducing hydrogen ion concentration in acidic anion eluate

    International Nuclear Information System (INIS)

    A procedure is suggested for reducing the concentration of hydrogen ions in the acidic anionic eluate formed during the separation of uranium. The procedure involves anex elution, precipitation, filtration, precipitate rinsing, and anex rinsing. The procedure is included in the uranium elution process and requires at least one ion exchanger column and at least one tank in the continuous or discontinuous mode. Sparing the neutralizing agent by reducing the hydrogen ion concentration in the acidic anionic eluate is a major asset of this procedure. (Z.S.). 1 fig

  13. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup −}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  14. A lanthanide complex for metal encapsulations and anion exchanges.

    Science.gov (United States)

    Sun, Yan-Qiong; Wan, Fang; Li, Xin-Xiong; Lin, Jian; Wu, Tao; Zheng, Shou-Tian; Bu, Xianhui

    2016-08-01

    A cationic lanthanide metalloligand with 3 dangling carboxylate groups on its periphery co-assembles with nitrate into a porous thermochromic solid responsive to both external cations and anions, owing to the presence of exchangeable NO3(-) as well as cation cavities arising from cooperative orientation of free carboxylate groups. An especially interesting feature is the structural memory effect during crystallization exhibited by the metalloligand, even after dissolution and binding to secondary cations (Cu(2+), Cd(2+)…). Moreover, the porous solid can undergo ion-exchange with various anions, leading to tunable thermochromic temperature and color range. PMID:27463609

  15. Gas-grain models for interstellar anion chemistry

    OpenAIRE

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    Long-chain hydrocarbon anions CnH- (n=4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances ...

  16. Electron Photodetachment from Aqueous Anions. I. Quantum Yields for Generation of Hydrated Electron by 193 and 248 nm Laser Photoexcitation of Miscellaneous Inorganic Anions

    CERN Document Server

    Sauer, M C; Shkrob, I A; Sauer, Myran C.; Shkrob, Ilya A.

    2004-01-01

    Time resolved transient absorption spectroscopy has been used to determine quantum yields for electron photodetachment in 193 nm and (where possible) 248 nm laser excitation of miscellaneous aqueous anions, including hexacyanoferrate(II), sulfate, sulfite, halide anions (Cl-, Br-, and I-), pseudohalide anions (OH-, HS-, CNS-), and several common inorganic anions for which no quantum yields have been reported heretofore: SO3=, NO2-, NO3-, ClO3- and ClO4-. Molar extinction coefficients for these anions and photoproducts of electron detachment from these anions at the excitation wavelengths were also determined. These results are discussed in the context of recent ultrafast kinetic studies and compared with the previous data obtained by product analyses. We suggest using electron photodetachment from the aqueous halide and pseudohalide anions as actinometric standard for time-resolved studies of aqueous photosystems in the UV.

  17. Anion-Anion Bonding and Topology in Ternary Iridium Seleno-Stannides

    Energy Technology Data Exchange (ETDEWEB)

    Trump, Benjamin A.; Tutmaher, Jake A.; McQueen, Tyrel M. [JHU

    2016-09-06

    The synthesis and physical properties of two new and one known Ir–Sn–Se compound are reported. Their crystal structures are elucidated with transmission electron microscopy and powder X-ray diffraction. IrSn0.45Se1.55 is a pyrite phase which consists of tilted corner-sharing IrX6 octahedra with randomly distributed (Sn–Se)4– and (Se–Se)2– dimers. Ir2Sn3Se3 is a known trigonally distorted skutterudite that consists of cooperatively tilted corner-sharing IrSn3Se3 octahedra with ordered (Sn–Se)24– tetramers. Ir2SnSe5 is a layered, distorted β-MnO2 (pyrolusite) structure consisting of a double IrSe6 octrahedral row, corner sharing in the a direction and edge sharing in the b direction. This distorted pyrolusite contains (Se–Se)2– dimers and Se2– anions, and each double row is “capped” with a (Sn–Se)n polymeric chain. Resistivity, specific heat, and magnetization measurements show that all three have insulating and diamagnetic behavior, indicative of low-spin 5d6 Ir3+. Electronic structure calculations on Ir2Sn3Se3 show a single, spherical, nonspin–orbit split valence band and suggest that Ir2Sn3Se3 is topologically nontrivial under tensile strain due to inversion of Ir-d and Se-p states.

  18. A new anionic exchange stir bar sorptive extraction coating based on monolithic material for the extraction of inorganic anion.

    Science.gov (United States)

    Huang, Xiaojia; Lin, Jianbing; Yuan, Dongxing

    2010-07-23

    A novel anionic exchange stir bar sorptive extraction (SBSE) coating based on poly(2-(methacryloyloxy)ethyltrimethylammonium chloride-co-divinylbenzene) monolithic material for the extraction of inorganic anion was prepared. The effect of preparation conditions such as ratio of functional monomer to cross-linker, content of porogenic solvent on the extraction efficiencies were investigated in detailed. The monolithic material was characterized by elemental analysis, scanning electron microscopy and infrared spectroscopy. In order to investigate the extraction capacity of the new coating for inorganic anion, the new SBSE was combined with ionic chromatography with conductivity detection, Br-, NO3-, PO4(3-) and SO4(2-) were selected as detected solutes. Several extractive parameters, including pH value and ionic strength in sample matrix, desorption solvent, extraction and desorption time were optimized. The results showed that strongly ionic strength did not favor the extraction of anlaytes. Under the optimum experimental conditions, low detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method for the target anions were achieved within the range of 0.92-2.62 and 3.03-9.25 microg/L, respectively. The method also showed good linearity, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was successfully used to detect the two different trademarks of commercial purified water with satisfactory recovery in the range of 70.0-92.6%. To the best of our knowledge, this is the first to use SBSE to enrich inorganic anions. PMID:20576270

  19. Rejuvenation processes applied to 'poisoned' anion exchangers in uranium processing

    International Nuclear Information System (INIS)

    The removal of 'poisons' from anion exchangers in uranium processing of Canadian radioactive ores is commonly called rejuvenation or regeneration. The cost of the ion exchange recovery of uranium is adversely affected by a decrease in the capacity and efficiency of the anion exchangers, due to their being 'poisoned' by silica, elemental sulphur, molybdenum and tetrathionates. These 'poisons' have a high affinity for the anion exchangers, are adsorbed in preference to the uranyl complex, and do not desorb with the reagents used normally in the uranyl desorption phase. The frequency of rejuvenation and the reagents required for rejuvenation are determined by the severity of the 'poisoning' accumulated by the exchanger in contact with the uranium leach liquor. Caustic soda (NaOH) at approximately equal to 18 cents/lb is commonly used to remove uranium anion exchangers of tetrathionate ((S406)/-/-) 'poisons'. A potential saving in operating cost would be of consequence if other reagents, e.g. sodium carbonate (Na2CO3) at approximately equal to 3.6 cents/lb or calcium hydroxide (Ca(OH)2) at approximately equal to 1.9 cents/lb, were effective in removing (S406)/-/-) from a 'poisoned' exchanger. A rejuvenation process for a test program was adopted after a perusal of the literature

  20. Synthesis and Anion Recognition of a Novel Heterocyclic Organotin Complex

    Institute of Scientific and Technical Information of China (English)

    Li Xin ZHANG; Gui Zhi LI; Zhi Qiang LI

    2004-01-01

    A novel heterocyclic hexacoordinate organotin(IV) complex, bis(O-vanillin)-semi ethylenediamino dibenzyltin (VEDBT) was synthesized by the reaction of dibenzyltin dichloride with bis(O-vanillin)-semiethyenediamine, its structure has been characterized by spectral methods.The electrodes using VEDBT as a neutral carrier show high selectivity for salicylate anions.

  1. Comment on "Local impermeant anions establish the neuronal chloride concentration".

    Science.gov (United States)

    Voipio, Juha; Boron, Walter F; Jones, Stephen W; Hopfer, Ulrich; Payne, John A; Kaila, Kai

    2014-09-01

    Glykys et al. (Reports, 7 February 2014, p. 670) conclude that, rather than ion transporters, "local impermeant anions establish the neuronal chloride concentration" and thereby determine "the magnitude and direction of GABAAR currents at individual synapses." If this were possible, perpetual ion-motion machines could be constructed. The authors' conclusions conflict with basic thermodynamic principles.

  2. Photocatalytic Anion Oxidation and Applications in Organic Synthesis.

    Science.gov (United States)

    Hering, Thea; Meyer, Andreas Uwe; König, Burkhard

    2016-08-19

    Ions and radicals of the same kind differ by one electron only. The oxidation of many stable inorganic anions yields their corresponding highly reactive radicals, and visible light excitable photocatalysts can provide the required oxidation potential for this transformation. Air oxygen serves as the terminal oxidant, or cheap sacrificial oxidants are used, providing a very practical approach for generating reactive inorganic radicals for organic synthesis. We discuss in this perspective several recently reported examples: Nitrate radicals are obtained by one-electron photooxidation of nitrate anions and are very reactive toward organic molecules. The photooxidation of sulfinate salts yields the much more stable sulfone radicals, which smoothly add to double bonds. A two-electron oxidation of chloride anions to electrophilic chlorine species reacting with arenes in aromatic substitutions extends the method beyond radical reactions. The chloride anion oxidation proceeds via photocatalytically generated peracidic acid as the oxidation reagent. Although the number of reported examples of photocatalytically generated inorganic radical intermediates for organic synthesis is still small, future extension of the concept to other inorganic ions as radical precursors is a clear perspective.

  3. The Determination of Anionic Surfactants in Natural and Waste Waters.

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

    Background information, procedures, and results of an experiment suitable for measuring subpart per million concentrations of anionic surfactants in natural waters and waste effluents are provided. The experiment required only a spectrophotometer or filter photometer and has been successfully performed by students in an undergraduate environmental…

  4. Molecular Anions in Protostars, Prestellar Cores and Dark Clouds

    Science.gov (United States)

    Cordiner, Martin; Charnley, Steven; Buckle, Jane; Wash, Catherine; Millar, Tom

    2011-01-01

    From our recent survey work using the Green Bank Telescope, microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H have been detected in six new sources. Using HC3N = 10(exp -9) emission maps, we targeted the most carbon-chain-rich sources for our anion survey, which included the low-mass Class 0 protostar L1251A-IRS3, the prestellar cores L1389-SMM1 and L1512, and the interstellar clouds Ll172A, TMC-1C and L1495B. Derived [C6H(-)]/[C6H] anion-to-neutral ratios are approximately 1-10. The greatest C6H(-) column densities are found in the quiescent clouds TMC-1C and L1495B, but the anion-to-neutral ratios are greatest in the prestellar cores and protostars. These results are interpreted in terms of the physical and chemical properties of the sources, and the implications for molecular cloud chemistry are discussed.

  5. Oxidation of silicon surface with atomic oxygen radical anions

    Institute of Scientific and Technical Information of China (English)

    Wang Lian; Song Chong-Fu; Sun Jian-Qiu; Hou Ying; Li Xiao-Guang; Li Quan-Xin

    2008-01-01

    The surface oxidation of silicon (Si) wafers by atomic oxygen radical anions (O- anions) and the preparation of metal-oxide-semiconductor (MOS) capacitors on the O--oxidized Si substrates have been examined for the first time. The O- anions are generated from a recently developed O- storage-emission material of [Ca24Al28O64]4+.4O- (C12A7-O- for short). After it has been irradiated by an O- anion beam (0.5 μA/cm2) at 300℃ for 1-10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy (XPS) results reveal that the oxide layer is of a mixture of SiO2, Si2O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of are investigated by measuring capacitance-voltage (C - V) and current-voltage (Ⅰ - Ⅴ) curves. The oxide charge density is about 6.0×1011 cm-2 derived from the C - V curves. The leakage current density is in the order of 10-6 A/cm2 below 4 MV/cm, obtained from the Ⅰ - Ⅴ curves. The Oanions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.

  6. Spectral modulation through controlling anions in nanocaged phosphors

    NARCIS (Netherlands)

    H. Bian; Y. Liu; D. Yan; H. Zhu; C. Liu; C.S. Xu; Y. Liu; H. Zhang; X. Wang

    2013-01-01

    A new approach has been proposed and validated to modulate the emission spectra of europium-doped 12CaO center dot 7Al(2)O(3) phosphors by tuning the nonradiative and radiative transition rates, realized by controlling the sort and amount of the encaged anions. A single wavelength at 255 nm can exci

  7. Advancing Analytical Methods for Characterization of Anionic Carbohydrate Biopolymers

    OpenAIRE

    Langeslay, Derek Joseph

    2013-01-01

    The focus of this dissertation is on the development of improved analytical methods for the characterization of anionic carbohydrate biopolymers. Our goal is to extract important information from complex mixtures of heterogeneous polysaccharides by characterizing their substituent oligosaccharides in terms of monosaccharide composition and primary and secondary structure. This work focuses on the application of two major analytical platforms: spectroscopy and chromatography. The development ...

  8. Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes

    OpenAIRE

    Schultz, Alison

    2013-01-01

           Ion-containing block copolymers blend ionic liquid properties with well-defined polymer architectures. This provides conductive materials with robust mechanical stability, efficient processability, and tunable macromolecular design. Conventional free radical polymerization and anion exchange achieved copolymers containing n-butyl acrylate and phosphonium ionic liquids. These compositions incorporated vinylbenzyl triphenyl phosphonium and vinylbenzyl tricyclohexyl phosphonium cations be...

  9. Reducing nitrogen crossover in microbial reverse-electrodialysis cells by using adjacent anion exchange membranes and anion exchange resin

    KAUST Repository

    Wallack, Maxwell J.

    2015-01-01

    Microbial reverse electrodialysis cells (MRECs) combine power generation from salinity gradient energy using reverse electrodialysis (RED), with power generation from organic matter using a microbial fuel cell. Waste heat can be used to distill ammonium bicarbonate into high (HC) and low salt concentration (LC) solutions for use in the RED stack, but nitrogen crossover into the anode chamber must be minimized to avoid ammonia loses, and foster a healthy microbial community. To reduce nitrogen crossover, an additional low concentration (LC) chamber was inserted before the anode using an additional anion exchange membrane (AEM) next to another AEM, and filled with different amounts of anion or cation ion exchange resins. Addition of the extra AEM increased the ohmic resistance of the test RED stack from 103 Ω cm2 (1 AEM) to 295 Ω cm2 (2 AEMs). However, the use of the anion exchange resin decreased the solution resistance of the LC chamber by 74% (637 Ω cm2, no resin; 166 Ω cm2 with resin). Nitrogen crossover into the anode chamber was reduced by up to 97% using 50% of the chamber filled with an anion exchange resin compared to the control (no additional chamber). The added resistance contributed by the use of the additional LC chamber could be compensated for by using additional LC and HC membrane pairs in the RED stack.

  10. Controlled Release Kinetics in Hydroxy Double Salts: Effect of Host Anion Structure

    OpenAIRE

    Stephen Majoni; Jeanne M. Hossenlopp

    2014-01-01

    Nanodimensional layered metal hydroxides such as layered double hydroxides (LDHs) and hydroxy double salts (HDSs) can undergo anion exchange reactions releasing intercalated anions. Because of this, these metal hydroxides have found applications in controlled release delivery of bioactive species such as drugs and pesticides. In this work, isomers of hydroxycinnamate were used as model compounds to systematically explore the effects of anion structure on the rate and extent of anion release i...

  11. Synthesis of unsymmetrical N-carboranyl NHCs: directing effect of the carborane anion.

    Science.gov (United States)

    Asay, Matthew J; Fisher, Steven P; Lee, Sarah E; Tham, Fook S; Borchardt, Dan; Lavallo, Vincent

    2015-03-28

    The syntheses of unsymmetrical N-heterocyclic carbenes (NHCs) that contain a single N-bound icosahedral carborane anion substituent are reported. Both anionic C-2 and doubly deprotonated dianionic C-2/C-5 NHC lithium complexes are isolated. The latter species is formed selectively, which reveals a surprising directing effect conveyed by icosahedral carborane anion substituents. PMID:25387660

  12. Improving the Enzyme Catalytic Efficiency Using Ionic Liquids with Kosmotropic Anions

    Institute of Scientific and Technical Information of China (English)

    ZHAO, Hua; CAMPBELL, Sophia; SOLOMON, Jonathan; SONG, Zhi-Yan; OLUBAJO, Olarongbe

    2006-01-01

    The kosmotropicity of cations and anions in ionic liquids has a strong influence on the enzyme catalytic efficiency in aqueous environments. The kosmotropic anion CF3COO- seemed to activate the protease, and the chaotropic anions tended to destabilize the enzyme.

  13. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance. Final Report

    International Nuclear Information System (INIS)

    increased understanding of the chemical rules that govern the selective sequestration of anions.

  14. Synthetic ion transporters that work with anion-π interactions, halogen bonds, and anion-macrodipole interactions.

    Science.gov (United States)

    Vargas Jentzsch, Andreas; Hennig, Andreas; Mareda, Jiri; Matile, Stefan

    2013-12-17

    The transport of ions and molecules across lipid bilayer membranes connects cells and cellular compartments with their environment. This biological process is central to a host of functions including signal transduction in neurons and the olfactory and gustatory sensing systems, the translocation of biosynthetic intermediates and products, and the uptake of nutrients, drugs, and probes. Biological transport systems are highly regulated and selectively respond to a broad range of physical and chemical stimulation. A large percentage of today's drugs and many antimicrobial or antifungal agents take advantage of these systems. Other biological transport systems are highly toxic, such as the anthrax toxin or melittin from bee venom. For more than three decades, organic and supramolecular chemists have been interested in developing new transport systems. Over time, curiosity about the basic design has evolved toward developing of responsive systems with applications in materials sciences and medicine. Our early contributions to this field focused on the introduction of new structural motifs with emphasis on rigid-rod scaffolds, artificial β-barrels, or π-stacks. Using these scaffolds, we have constructed selective systems that respond to voltage, pH, ligands, inhibitors, or light (multifunctional photosystems). We have described sensing applications that cover the three primary principles of sensor development: immunosensors that use aptamers, biosensors (an "artificial" tongue), and differential sensors (an "artificial" nose). In this Account, we focus on our recent interest in applying synthetic transport systems as analytical tools to identify the functional relevance of less common noncovalent interactions, anion-π interactions, halogen bonds, and anion-macrodipole interactions. Anion-π interactions, the poorly explored counterpart of cation-π interactions, occur in aromatic systems with a positive quadrupole moment, such as TNT or hexafluorobenzene. To observe

  15. Facile synthesis of hollow silica nanospheres employing anionic PMANa templates

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yan; Takai, Chika; Shirai, Takashi; Fuji, Masayoshi, E-mail: fuji@nitech.ac.jp [Nagoya Institute of Technology, Advanced Ceramic Research Center (Japan)

    2015-05-15

    This article presents a facile and green route to the synthesis of hollow silica particles by means of anionic particles of poly(sodium methacrylate) (PMANa) as templates. This method was composed of the following three steps: formation of PMANa particles in ethanol by nanoprecipitation, the deposition of silica shell on the polymer cores through sol–gel process of tetraethylorthosilicate under catalysis of ammonia, and removal of the polymer templates by washing with water. The templates’ size can be controlled in the range of about 70–140 nm by altering the ratio of ethanol to water, the polymer solution concentration, the ethanol amount in polymer solution, and the silica shell thickness can be adjusted between 15 and 30 nm by varying the ratio of silica precursor to the polymer cores. A tentative interpretation about the silica-coating process on the anionic PMANa particles was also proposed according to the experimental results.

  16. Macrocyclic bis(ureas as ligands for anion complexation

    Directory of Open Access Journals (Sweden)

    Claudia Kretschmer

    2014-08-01

    Full Text Available Two macrocyclic bis(ureas 1 and 2, both based on diphenylurea, have been synthesized. Compound 1 represents the smaller ring with two ethynylene groups as linkers and 2 the larger ring with two butadiynylene groups. On thermal treatment to 130 °C molecule 1 splits up into two dihydroindoloquinolinone (3 molecules. Both compounds 1 and 2 form adducts with polar molecules such as dimethyl sulfoxide (DMSO and dimethylformamide (DMF and act as complexing agents towards a series of anions (Cl−, Br−, I−, NO3−, HSO4−. The crystal structures of 3, 2·2DMSO, 2·2DMF, and of the complex NEt4[Br·2] have been determined. Quantitative investigations of the complexation equilibria were performed via 1H NMR titrations. While 1 is a rather weak complexing agent, the large ring of 2 binds anions with association constants up to log K = 7.93 for chloride ions.

  17. Epithelial Anion Transport as Modulator of Chemokine Signaling

    Science.gov (United States)

    Schnúr, Andrea; Hegyi, Péter; Rousseau, Simon; Lukacs, Gergely L.; Veit, Guido

    2016-01-01

    The pivotal role of epithelial cells is to secrete and absorb ions and water in order to allow the formation of a luminal fluid compartment that is fundamental for the epithelial function as a barrier against environmental factors. Importantly, epithelial cells also take part in the innate immune system. As a first line of defense they detect pathogens and react by secreting and responding to chemokines and cytokines, thus aggravating immune responses or resolving inflammatory states. Loss of epithelial anion transport is well documented in a variety of diseases including cystic fibrosis, chronic obstructive pulmonary disease, asthma, pancreatitis, and cholestatic liver disease. Here we review the effect of aberrant anion secretion with focus on the release of inflammatory mediators by epithelial cells and discuss putative mechanisms linking these transport defects to the augmented epithelial release of chemokines and cytokines. These mechanisms may contribute to the excessive and persistent inflammation in many respiratory and gastrointestinal diseases. PMID:27382190

  18. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    S Radha; P Vishnu Kamath

    2013-10-01

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal charge transfer transitions of the ferricyanide anion show a red shift on intercalation. The ferrocyanide ion shows a significant blue shift of – bands due to the increased separation between 2g and g levels on intercalation. MnO$^{-}_{4}$ ion shows a blue shift in its ligand to metal charge transfer transition since the non-bonding 1 level of oxygen from which the transition arises is stabilized.

  19. Coumarin Based Neutral Sensor for Biologically Important Anions

    Institute of Scientific and Technical Information of China (English)

    SHAO Jie

    2011-01-01

    A coumarin Shiff-base derivative,salicylaldehyde-N-(6-phenylazo-coumarin-3-formyl)-hydrazone(1),was obtained by simple organic synthesis from cheap and commercially available starting materials.Sensor 1 exhibits a very weak fluorescence emission,however,in the presence of acetate ions “turn-on” fluorescence is observed,which results from binding-induced conformational restriction of the fluorophore.Importantly,sensor 1 can also be used as colorimetric chemosensor for the anions with strong basicity,which is easily observed from yellow to red by naked eyes.Consequently,compound l can behave as a colorimetric and fluorescence sensor for biologically important F,CH3COO and H2PO4- in the presence of the other anions tested such as Cl-,Br- and I- in dimethyl sulfoxide(DMSO).

  20. Microsolvation effects on the electron binding energies of halide anions

    Science.gov (United States)

    Dolgounitcheva, O.; Zakrzewski, V. G.; Streit, L.; Ortiz, J. V.

    2014-02-01

    Ab initio electron propagator calculations in the partial third order (P3) and P3+ approximations were performed to obtain vertical electron detachment energies (VEDEs) of fluoride and chloride clusters with one through three molecules of water. Larger clusters of F- and Cl- with six water molecules were also treated with and without the polarisable continuum model (PCM). For the smaller clusters, good agreement between calculated VEDEs and peak positions in photoelectron spectra is achieved. Large shifts in VEDEs are observed for both hexameric fluoride-water and chloride-water complexes when the PCM is applied. Significant changes in coordination geometries about the chloride anion also occur in this model. In all fluoride complexes, Dyson orbitals for the lowest VEDEs are delocalised over oxygen atoms. On the contrary, for the case of chloride-water clusters, the Dyson orbitals corresponding to the lowest VEDEs are localised on the anion.

  1. Thermal Properties of Anionic Polyurethane Composition for Leather Finishing

    Directory of Open Access Journals (Sweden)

    Olga KOVTUNENKO

    2016-09-01

    Full Text Available Thermal properties of anionic polyurethane composition mixed with collagen product and hydrophilic sodium form of montmorillonite for use in the finishing of leather were studied by thermogravimetric method. The thermal indices of processes of thermal and thermo-oxidative destruction depending on the polyurethane composition were determined. The influence of anionic polyurethane composition on thermal behavior of chromium tanned gelatin films that imitate the leather were studied. APU composition with natural compounds increases their thermal stability both in air and in nitrogen atmosphere due to the formation of additional bonds between active groups of APU, protein and chrome tanning agent as the result of chemical reactions between organic and inorganic parts with the new structure formation.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.10043

  2. Enhanced conductivity detection of common inorganic anions in electrostatic ion chromatography using water eluent

    Institute of Scientific and Technical Information of China (English)

    Daisuke KOZAKI; Chao-Hong SHI; Kazuhiko TANAKA; Nobutake NAKATANI

    2012-01-01

    To enhance the conductivity detection sensitivity of common anions (Na-anions) in electrostatic ion chromatography (EIC) by elution with water,a conductivity enhancement column packed with strong acid cation exchange resin in the H-form was inserted between an octadecyl silane (ODS)-silica separation column modified with zwitterionic surfactant ( CHAPS:3- { ( 3-cholamidopropyl ) -dimethylammonio } propanesulfonate ) and a conductivity detector.Specifically,the Na-anion pairing is converted to H-anion pairing after the EIC separation and then detected sensitively by the conductivity detector.The effects of conductivity enhancement and suppression in the EIC by the enhanced conductivity detection were characterized for the common strong acid anions such as SO42-,Cl-,NO3-,I- and ClO4- and weak acid anions such as F-,NO2-,HCOO-,CH3COO- and HCO3-.For the conductivity enhancement effect in the EIC,it is found that the conductivity of measured for all strong acid anions (Na-anions) was enhanced acording to the theoretical conductivity predicted for H-anions and that of the measured for weak acid anions was suppressed depending on their pKa of H-anions.For the calibration linearity in the EIC,the strong acid anions were linear (r2 =0.99 - 1.00) because the degree of dissociation is almost 1.0 over all the concentration range and that of the weak acid anions was non-linear because the degree of dissociation decreased by increasing the concentration of the weak acid anions.In conclusion,the EIC by enhanced conductivity detection was recognized to be useful only for the strong acid anions in terms of conductivity detection and calibration linearity.

  3. Quasielastic neutron scattering study of tetrahydroborate anion dynamical perturbations in sodium borohydride due to partial halide anion substitution

    Energy Technology Data Exchange (ETDEWEB)

    Verdal, Nina [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Udovic, Terrence J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Rush, John J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Skripov, Alexander V. [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation)

    2015-10-05

    Highlights: • NaBH{sub 4}–NaX (X = Cl, I) solutions were made by ball-milling/annealing pure compounds. • BH{sub 4}{sup −} reorientational motions were studied by quasielastic neutron scattering. • Mobility increased from X = Cl to NaBH{sub 4} to X = I, consistent with expanding lattices. • Near 400 K, BH{sub 4}{sup −} favored cubic tumbling for X = Cl and tetrahedral tumbling for X = I. • Activation energies were in the range of 11–12 kJ mol{sup −1} for both compounds. - Abstract: Equimolar NaBH{sub 4}–NaX (X = Cl and I) solid solutions were synthesized to study, via quasielastic neutron scattering, the effect of partial halide anion substitution on the reorientational dynamics of tetrahydroborate (BH{sub 4}{sup −}) anions in NaBH{sub 4}. The BH{sub 4}{sup −} reorientational mobility increased in the order of NaBH{sub 4}–NaCl, NaBH{sub 4}, and NaBH{sub 4}–NaI, which corresponded with expanding face-centered-cubic lattices accommodating the respective increasing sizes of the Cl{sup −}, BH{sub 4}{sup −}, and I{sup −} anions. The BH{sub 4}{sup −} anions in NaBH{sub 4}–NaCl were found (at least above 400 K) to undergo ‘cubic’ tumbling motions with the four H atoms per anion visiting all eight corners of a cube, similar to what was previously observed for NaBH{sub 4}. In contrast, the BH{sub 4}{sup −} anions in NaBH{sub 4}–NaI were found to undergo something more akin to ‘tetrahedral’ tumbling motions, where the H atoms visit all four corners of a tetrahedron. Despite a noticeable softening of the BH{sub 4}{sup −} torsional energies with increasing lattice constant amongst NaBH{sub 4} and the two solid solutions, all three compounds exhibited similar activation energies for reorientation of about 11–12 kJ mol{sup −1}.

  4. Impact of microstructure on anion exclusion in compacted clay media

    OpenAIRE

    Tournassat, Christophe; Gaboreau, Stéphane; Robinet, Jean-Charles; Bourg, Ian C.; Steefel, Carl I

    2015-01-01

    International audience The sensitivity of ion concentration distribution models to three key model assumptions, the pore-size distribution of clay media, the distance of closest approach of ions to the clay surface, and the accessibility of sub-nanometer-wide clay mineral interlayer spaces to anions, was explored by solving the Poisson-Boltzmann equation for swelling and non-swelling clay materials. Our calculations show that all three model assumptions significantly impact values predicte...

  5. Organic resin anion exchangers for the treatment of radioactive wastes

    International Nuclear Information System (INIS)

    Organic anion exchange resins are evaluated for 99-TcO4- (pertechnate) removed from aqueous nuclear waste streams. Chemical, thermal and radiation stabilities were studied. Selected resins were examined in detail for their selectivities in the presence of I-, NO3-, SO4=, CO3=, Cl- and OH-. Ion exchange equilibria and kinetic mechanisms were determined. Preliminary investigations of cement encapsulation in polymer modified form were made and some leach studies carried out. (author)

  6. Inorganic anion exchangers for the treatment of radioactive wastes

    International Nuclear Information System (INIS)

    Inorganic anion exchangers are evaluated for Tc, I and S isotope removal from aqueous nuclear waste streams. Chemical, thermal, and radiation stabilities were examined. Selected exchangers were examined in detail for their selectivities, kinetics and mechanism of the sorption process (especially in NO3-, OH- and BO3- environments). Cement encapsulation and leaching experiments were made on the exchangers showing most promise for 'radwaste' treatment. (author)

  7. Factors Affecting Anion Movement and Retention in Four Forest Soils

    OpenAIRE

    D. W. Johnson; Cole, D. W.; Van Miegroet, Helga; Horng, F. W.

    1986-01-01

    Three hypotheses concerning the movement and retention of anions in forest soils were tested in a series of laboratory and field studies on two Tennessee Ultisols with mixed deciduous forest cover and two Washington Inceptisols, one with deciduous (red alder Alnus rubra Bong.) and one with coniferous [Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco] forest cover. The first hypothesis, that sulfate and phosphate retention was related to adsorption to free Fe and Al oxides, which were in turn...

  8. Synthesis of Cationic Extended Frameworks for Anion-Based Applications

    OpenAIRE

    Fei, Honghan

    2012-01-01

    Many of the metal pollutants listed as priorities by the EPA (U.S. Environmental Protection Agency) occur in water as their oxo-hydroxo anionic forms (e.g. perchlorate, chromate, selenite, etc.). Radioactive technetium (Tc-99) in the form of soluble pertechnetate (TcO4−) is highly problematic in low-activity waste (LAW) to separate the nuclear waste into primary solids. Its easy leakage from glass after vitrification does not meet long-term storage performance assessment requirements. ...

  9. Alkaline Anion-Exchange Membranes Containing Mobile Ion Shuttles.

    Science.gov (United States)

    Ge, Xiaolin; He, Yubin; Guiver, Michael D; Wu, Liang; Ran, Jin; Yang, Zhengjin; Xu, Tongwen

    2016-05-01

    A new class of alkaline anion-exchange membranes containing mobile ion shuttles is developed. It is achieved by threading ionic linear guests into poly(crown ether) hosts via host-guest molecular interaction. The thermal- and pH-triggered shuttling of ionic linear guests remarkably increases the solvation-shell fluctuations in inactive hydrated hydroxide ion complexes (OH(-) (H2 O)4 ) and accelerates the OH(-) transport. PMID:26972938

  10. A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes

    OpenAIRE

    Yubin He; Jiefeng Pan; Liang Wu; Yuan Zhu; Xiaolin Ge; Jin Ran; ZhengJin Yang; Tongwen Xu

    2015-01-01

    Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH− conductiv...

  11. Comment on "Local impermeant anions establish the neuronal chloride concentration".

    Science.gov (United States)

    Luhmann, Heiko J; Kirischuk, Sergei; Kilb, Werner

    2014-09-01

    Glykys et al. (Reports, 7 February 2014, p. 670) proposed that cytoplasmic impermeant anions and polyanionic extracellular matrix glycoproteins establish the local neuronal intracellular chloride concentration, [Cl(-)]i, and thereby the polarity of γ-aminobutyric acid type A (GABAA) receptor signaling. The experimental procedures and results in this study are insufficient to support these conclusions. Contradictory results previously published by these authors and other laboratories are not referred to.

  12. Chemistry of nitrile anions in the interstellar medium

    International Nuclear Information System (INIS)

    Despite the extreme conditions of temperature (down to 10K) and density (down to 100 molecules/cm3), the giant molecular clouds and the circumstellar envelopes present a rich and complex chemistry. To date, more than 180 molecules have been detected in the InterStellar Medium (ISM) with a large abundance of nitriles (RC≡N). In addition, several anions have been recently observed in this medium: C4H¯, C6H¯, C8H¯, CN¯, C3N¯ and C5N¯. These last species should play a key role in the molecular growth towards complexity. To explore this hypothesis, their reactivity must be studied in the laboratory. The FALP-MS and the CRESU experimental apparatuses of the Rennes University are able to measure absolute rate coefficient of various chemical reactions, including the ion – molecule reactions, in gas phase at low temperature (from 300K for the FALP-MS down to 15K for the CRESU). Therefore, these experimental tools are particularly adapted to the kinetic studies of reactions potentially involved in the Interstellar Medium. One of the difficulties encountered in experiments with anions is their generation. We describe here the formation of the CN¯ and C3N¯ anions by dissociative electron attachment on the molecular precursors BrCN and BrC3N

  13. Phosphate Removal by Anion Binding on Functionalized Nanoporous Sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Chouyyok, Wilaiwan; Wiacek, Robert J.; Pattamakomsan, Kanda; Sangvanich, Thanapon; Grudzien, Rafal M.; Fryxell, Glen E.; Yantasee, Wasanna

    2010-03-26

    Phosphate was captured from aqueous solutions by cationic metal-EDA complexes anchored inside mesoporous silica MCM-41 supports (Cu(II)-EDA-SAMMS and Fe(III)-EDA-SAMMS). Fe-EDA-SAMMS was more effective at capturing phosphate than the Cu-EDA-SAMMS and was further studied for matrix effects (e.g., pH, ionic strength, and competing anions) and sorption performance (e.g., capacity and rate). The adsorption of phosphate was highly pH dependent; it increased with increasing pH from 1.0 to 6.5, and decreased above pH 6.5. The adsorption was affected by high ionic strength (0.1 M of NaCl). In the presence of 1000-fold molar excess of chloride and nitrate anions, phosphate removal by Fe-EDA-SAMMS was not affected. Slight, moderate and large impacts were seen with bicarbonate, sulfate and citrate anions, respectively. The phosphate adsorption data on Fe-EDA-SAMMS agreed well with the Langmuir model with the estimated maximum capacity of 43.3 mg/g. The material displayed rapid sorption rate (99% of phosphate removal within 1 min) and lowering the phosphate content to ~ 10 µg/L of phosphorus, which is lower than the EPA’s established freshwater contaminant level for phosphorous (20 µg/L).

  14. Stability of atoms in the anionic domain (Z

    CERN Document Server

    Gil, G

    2013-01-01

    We study the stability and universal behaviour of the ionization energy of N-electron atoms with nuclear charge Z in the anionic domain (Zanionic instability threshold. As testing systems we choose inert gases (He-like, Ne-like and Ar-like isoelectronic sequences) and alkali metals (Li-like, Na-like, K-like sequences). From the results, it is apparent that, for inert gases case, the stability relation with N is completely inverted in the singly-charged anion region (Z=N-1) with respect to the neutral atom region (Z=N), i.e. larger systems are more stable than the smaller ones. We devised a semi-analytical model (inspired by the zero-range forces theory) which lead us to establish the ionization energy dependence on the nuclear charge n...

  15. pH-Regulated Nonelectrogenic Anion Transport by Phenylthiosemicarbazones.

    Science.gov (United States)

    Howe, Ethan N W; Busschaert, Nathalie; Wu, Xin; Berry, Stuart N; Ho, Junming; Light, Mark E; Czech, Dawid D; Klein, Harry A; Kitchen, Jonathan A; Gale, Philip A

    2016-07-01

    Gated ion transport across biological membranes is an intrinsic process regulated by protein channels. Synthetic anion carriers (anionophores) have potential applications in biological research; however, previously reported examples are mostly nonspecific, capable of mediating both electrogenic and electroneutral (nonelectrogenic) transport processes. Here we show the transmembrane Cl(-) transport studies of synthetic phenylthiosemicarbazones mimicking the function of acid-sensing (proton-gated) ion channels. These anionophores have remarkable pH-switchable transport properties with up to 640-fold increase in transport efficacy on going from pH 7.2 to 4.0. This "gated" process is triggered by protonation of the imino nitrogen and concomitant conformational change of the anion-binding thiourea moiety from anti to syn. By using a combination of two cationophore-coupled transport assays, with either monensin or valinomycin, we have elucidated the fundamental transport mechanism of phenylthiosemicarbazones which is shown to be nonelectrogenic, inseparable H(+)/Cl(-) cotransport. This study demonstrates the first examples of pH-switchable nonelectrogenic anion transporters. PMID:27299473

  16. Conformational equilibrium of talin is regulated by anionic lipids.

    Science.gov (United States)

    Ye, Xin; McLean, Mark A; Sligar, Stephen G

    2016-08-01

    A critical step in the activation of integrin receptors is the binding of talin to the cytoplasmic domain of the β subunits. This interaction leads to separation of the integrin α and β transmembrane domains and significant conformational changes in the extracellular domains, resulting in a dramatic increase in integrin's affinity for ligands. It has long been shown that the membrane bilayer also plays a critical role in the talin-integrin interaction. Anionic lipids are required for proper interaction, yet the specificity for specific anionic headgroups is not clear. In this report, we document talin-membrane interactions with bilayers of controlled composition using Nanodiscs and a FRET based binding and structural assay. We confirm that recruitment of the talin head domain to the membrane surface is governed by charge in the absence of other adapter proteins. In addition, measurement of the donor-acceptor distance is consistent with the hypothesis that anionic lipids promote a conformational change in the talin head domain allowing interaction of the F3 domain with the phospholipid bilayer. The magnitude of the F3 domain movement is altered by the identity of the phospholipid headgroup with phosphatidylinositides promoting the largest change. Our results suggest that phoshpatidylinositol-4,5-bisphosphate plays key a role in converting talin head domain to a conformation optimized for interactions with the bilayer and subsequently integrin cytoplasmic tails.

  17. Anion composition of açaı́ extracts.

    Science.gov (United States)

    Liao, Hongzhu; Shelor, C Phillip; Chen, Yongjing; Sabaa-Srur, Armando U O; Smith, Robert E; Dasgupta, Purnendu K

    2013-06-26

    Many products labeled açaı́ are presently marketed as natural supplements with various claimed health benefits. Authentic açaı́ is expensive; as a result, numerous products labeled as containing açaı́ are being sold that actually contain little or no açaı́. Authentic açaı́ samples from Brazil and Florida as well as several reputed açaı́ products were analyzed by suppressed conductometric anion chromatography. Columns with different selectivities were used to obtain a complete separation of all anions. Tandem mass spectrometry was used for confirmation of the less common ions. Quinate, lactate, acetate, formate, galacturonate, chloride, sulfate, malate, oxalate, phosphate, citrate, isocitrate, and myo-inositol hexakisphosphate (phytate) were found. Only the Florida açaı́ had detectable levels of hexanoate. No açaı́ sample had any detectable levels of tartrate, which is present in abundance in grape juice, the most common adulterant. The highly characteristic anion profile and in particular the absence of tartrate can readily be used to identify authentic açaı́ products. Açaı́ from Florida had a 6 times greater level of phytate. The present analytical approach for phytate may be superior to extant methods.

  18. Coumarin benzothiazole derivatives as chemosensors for cyanide anions

    Science.gov (United States)

    Wang, Kangnan; Liu, Zhiqiang; Guan, Ruifang; Cao, Duxia; Chen, Hongyu; Shan, Yanyan; Wu, Qianqian; Xu, Yongxiao

    2015-06-01

    Four coumarin benzothiazole derivatives, N-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromene-3-carboxamide (1), (Z)-N-(3-methylbenzo[d]thiazol-2(3H)-ylidene)-2-oxo-2H-chromene-3-carboxamide (2), 7-(diethylamino)-N-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromene-3-carboxamide (3) and (Z)-7-(diethylamino)-N-(3-methylbenzo[d]thiazol-2(3H)-ylidene)-2-oxo-2H-chromene-3-carboxamide) (4), have been synthesized. Their crystal structures, photophysical properties in acetonitrile and recognition properties for cyanide anions have been investigated. All the compounds are generally planar, especially compound 1 exhibits perfect planarity with dihedral angle between benzothiazolyl group and coumarin group being only 3.63°. Coumarin benzothiazole compounds 1 and 3 can recognize cyanide anions by Michael addition reaction and compound 3 exhibits color change from yellow to colorless and green fluorescence was quenched completely, which can be observed by naked eye. Coumarin benzothiazolyliden compound 4 can recognize cyanide anions with fluorescence turn-on response based on the copper complex ensemble displacement mechanism.

  19. Effect of Anion on Adsorption of Rare Earth Elements on Kaolinite

    Institute of Scientific and Technical Information of China (English)

    Wan Yingxin; Liu Jianjun

    2007-01-01

    For a better understanding the adsorption of rare earth elements (REEs) on minerals and its controlling factors, adsorption experiments were performed with kaolin in a matrix of various concentration of anion (Cl-, ClO4-, SO42-) in the pH 6.5. The adsorption of REEs onto the kaolin increase with increasing anion concentration, especially in the presence of SO42-, which is ascribe to the Na+ mass effect and anion complexation. furthermore, the heavy REEs are more adsorbed onto kaolin in presence of higher concentration of anion, especially for Cl- and SO42-, presumably due to the difference of anion complexation with light REE and heavy REEs.

  20. Electron exchange between dipole-bound anion and polar molecule and dipole-bound anions dimer formation

    International Nuclear Information System (INIS)

    We consider collision between a dipole-bound molecular anion and a neutral polar molecule and show that the excess electron can bind two neutral molecules into a dimer. Using a variational approach similar to the Heitler-London model of H''+2 ion we obtain the energy terms of such a dimer. Their difference determines the cross-section of electron transfer from the anion to the neutral molecule in quasiclassical near-resonant Born-Oppenheimer approximation. We obtain for the cross-section an analytic expression containing the weak (logarythmic) factor depending on the molecular dipole moment, and collision velocity. Our analytic calculations are in a good accordance with the results of a recent experiment.

  1. Efficient, non-toxic anion transport by synthetic carriers in cells and epithelia

    Science.gov (United States)

    Li, Hongyu; Valkenier, Hennie; Judd, Luke W.; Brotherhood, Peter R.; Hussain, Sabir; Cooper, James A.; Jurček, Ondřej; Sparkes, Hazel A.; Sheppard, David N.; Davis, Anthony P.

    2016-01-01

    Transmembrane anion transporters (anionophores) have potential for new modes of biological activity, including therapeutic applications. In particular they might replace the activity of defective anion channels in conditions such as cystic fibrosis. However, data on the biological effects of anionophores are scarce, and it remains uncertain whether such molecules are fundamentally toxic. Here, we report a biological study of an extensive series of powerful anion carriers. Fifteen anionophores were assayed in single cells by monitoring anion transport in real time through fluorescence emission from halide-sensitive yellow fluorescent protein. A bis-(p-nitrophenyl)ureidodecalin shows especially promising activity, including deliverability, potency and persistence. Electrophysiological tests show strong effects in epithelia, close to those of natural anion channels. Toxicity assays yield negative results in three cell lines, suggesting that promotion of anion transport may not be deleterious to cells. We therefore conclude that synthetic anion carriers are realistic candidates for further investigation as treatments for cystic fibrosis.

  2. A fluorescent coumarin-thiophene hybrid as a ratiometric chemosensor for anions: Synthesis, photophysics, anion sensing and orbital interactions

    Science.gov (United States)

    Yanar, Ufuk; Babür, Banu; Pekyılmaz, Damla; Yahaya, Issah; Aydıner, Burcu; Dede, Yavuz; Seferoğlu, Zeynel

    2016-03-01

    A colorimetric and fluorimetric fluorescent chemosensor (CT-2), having a coumarin ring as a signaling unit and an acetamido thiophene ring as an H-donor receptor, has been synthesized from amino derivative (CT-1) of CT-2 for the purpose of recognition of anions in DMSO. The absorption and emission maxima were both determined for the fluorescent dye in different solvents. Both hypsochromic shift at the absorption maximum, and quenching of fluorescence after interactions between the anions and the receptoric part, were observed. This phenomenon was explained using orbital interactions based on quantum chemical calculations. The selectivity and sensitivity of CT-2 for F-, Cl-, Br-, I-, AcO-, CN-, H2PO4-, HSO4- and ClO4- anions were determined with spectrophotometric, fluorimetric and 1H NMR titration techniques and it was found that CT-2 be utilized for the detection of CN-, F- and AcO- in the presence of other ions as competitors. Color and fluorescence changes visible to the naked eye and under UV (365 nm) were observed upon addition of CN-, F- and AcO- to the solution of chemosensor (CT-2) in DMSO. The sensor showed no colorimetric and fluorimetric response for the anions such as Cl-, Br-, I-, H2PO4-, HSO4-, and ClO4-. However, 1H NMR titration shows that the chemosensor was more sensitive to CN-, than F- and AcO- at the stochiometric ratio of 1:2.5 respectively. Additionally, the compounds CT-1 and CT-2 showed good thermal stability for practical applications.

  3. Determination of arsenate in water by anion selective membrane electrode using polyurethane-silica gel fibrous anion exchanger composite.

    Science.gov (United States)

    Khan, Asif Ali; Shaheen, Shakeeba

    2014-01-15

    Polyurethane (PU)-silica (Si gel) based fibrous anion exchanger composites were prepared by solid-gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU-Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1×10(-8)M to 1×10(-1)M), response time (45s) and working pH range (5-8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO4(3-)) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

  4. M8L12 cubic cages with all facial Δ or facial Λ configuration: effects of surface anions on the occupancy of the cage and anion exchange.

    Science.gov (United States)

    Yang, Jing; Chang, Xiao-Yong; Sham, Kiu-Chor; Yiu, Shek-Man; Kwong, Hoi-Lun; Che, Chi-Ming

    2016-05-21

    M8L12 cubic cages (M = Mn(II), Zn(II) or Cd(II)), with all eight metal ions having all facial Δ or facial Λ configurations and having an encapsulated anion, were prepared by the self-assembly of m-xylene-bridged imidazolyl-imine ligands and MX2 (X = PF6(-), SbF6(-), TfO(-)) salts; the encapsulated anion exchange with different anions (SbF6(-), Tf2N(-), NO3(-), TsO(-)) was studied and the results with NO3(-) and TsO(-) indicate that anions on the cage surfaces affect the encapsulated anion exchange and the occupancy of the cage. PMID:27064122

  5. Solvation of benzophenone anion radical in ethanol and ethanol/2-methyltetrahydrofuran mixture

    International Nuclear Information System (INIS)

    The electron spin-echo modulations and the absoprtion spectra of benzophenone anion radicals generated by γ-irradiation in the glassy matrices of ethanol and ethanol2-methyltetrahydrofuran mixtures have been measured for elucidating the mechanism of spectral shift observed during the solvation of the anion radicals in alcohols. The anion radical generated at 4.2 K in the ethanol matrix maintains the same solvation structure as that of neutral benzophenone. At 77 K ethanol molecules solvate the anion radical by orienting the O-H dipoles toward the anion radical. The anion radical is hydrogen-bonded by two ethanol molecules through the p/sub z/ orbital on the benzophenone oxygen which composes the π orbitals of anion radical. Three kinds of anion radicals are observed in the mixed matrix at 77 K. Two of them are essentially the same as those observed in the ethanol matrix at 4.2 and 77 K. The third has the absorption maximum at 700 nm and is attributed to the anion radical hydrogen-bonded by one ethanol molecule through the p/sub z/ orbital. It is concluded that the spectral shift observed in alcohols is caused by the stabilization of a SOMO π* orbital induced by the hydrogen bonding with the (RO)H--O--H(OR) angle perpendicular to the molecular plane of the anion radical

  6. Adsorption and desorption dynamics of citric acid anions in soil

    KAUST Repository

    Oburger, E.

    2011-07-26

    The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes. © 2011 The

  7. Natural minerals and synthetic materials for sorption of radioactive anions

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Mun Ja; Chun, Kwan Sik; Kim, Seung Soo

    1998-07-01

    Technetium-99 and iodine-129 are fission products with long half-lives, and exist as highly soluble anionic species. Studies on natural and synthetic materials sorbing TcO{sub 4} and/or I have been performed by several researchers. The application of these materials as an additive in the high-level waste disposal has been considered. The iron- or sulfide-containing minerals such as metal iron, iron powder, stibnite and pyrrhotite show a high capacity for TcO{sub 4} sorption. And the small amounts of activated carbon are reported to have high distribution coefficients recently. In the iodine sorption studies, sulfide-, copper-, lead- or mercury-containing minerals can be a candidate. Pyrite, chalcopyrite, galena, Cu{sub 2}S and CuS reveal a high capacity for I sorption. The synthetic materials were found to have high sorption capacity and compensate the defects of natural minerals, which contain hydrous oxides such as zirconium oxide, aluminium oxide and mercarbide. The mercarbide has the high distribution coefficients for the sorption of TcO{sub 4} and I. Recently it was proposed that the synthetic clay, hydrotalcite, could be useful for the fixation of anion. However, to determine the applicability of those natural and synthetic materials as an additive to a buffer or backfill material for sorption of TcO{sub 4} and/or I, the sorption behavior of the anions on those materials under the repository conditions should be identified. (author). 32 refs., 21 tabs., 10 figs

  8. Chemistry of nitrile anions in the interstellar medium

    Energy Technology Data Exchange (ETDEWEB)

    Carles, S.; Le Garrec, J.-L.; Biennier, L. [Institut de Physique de Rennes, Département de Physique Moléculaire, Astrophysique de Laboratoire, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Guillemin, J.-C. [Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837,35708 Rennes Cedex 7 (France)

    2015-12-31

    Despite the extreme conditions of temperature (down to 10K) and density (down to 100 molecules/cm{sup 3}), the giant molecular clouds and the circumstellar envelopes present a rich and complex chemistry. To date, more than 180 molecules have been detected in the InterStellar Medium (ISM) with a large abundance of nitriles (RC≡N). In addition, several anions have been recently observed in this medium: C{sub 4}H{sup ¯}, C{sub 6}H{sup ¯}, C{sub 8}H{sup ¯}, CN{sup ¯}, C{sub 3}N{sup ¯} and C{sub 5}N{sup ¯}. These last species should play a key role in the molecular growth towards complexity. To explore this hypothesis, their reactivity must be studied in the laboratory. The FALP-MS and the CRESU experimental apparatuses of the Rennes University are able to measure absolute rate coefficient of various chemical reactions, including the ion – molecule reactions, in gas phase at low temperature (from 300K for the FALP-MS down to 15K for the CRESU). Therefore, these experimental tools are particularly adapted to the kinetic studies of reactions potentially involved in the Interstellar Medium. One of the difficulties encountered in experiments with anions is their generation. We describe here the formation of the CN{sup ¯} and C{sub 3}N{sup ¯} anions by dissociative electron attachment on the molecular precursors BrCN and BrC{sub 3}N.

  9. On the Adsorption of Some Anionic Collectors on Fluoride Minerals

    DEFF Research Database (Denmark)

    Sørensen, Emil

    1973-01-01

    Test flotations have been carried out in a small apparatus under standardized conditions in order to determine the dependence of the flotation yield on the reagent concentration for certain minerals and anionic collectors. The results suggest that a special adsorption mechanism is operating in th...... in the case of fluoride minerals, and a theory is presented which involves the joint action of ionic and hydrogen bonds. A precondition is the compatibility of the crystal geometry with the configuration of the polar group of the collector molecules....

  10. Ionic conductivity in crystal structures with isolated tetragonal anions

    International Nuclear Information System (INIS)

    A unique peculiarity - the presence of complex isolated tetrahedron anions TZK4(4y-Z), where K - oxygen or Hal atom, y - its valency, Z - T element valency, is showh to be characteristic for different groups of superionic conductors including complex oxides of zirconium, scandium and molybdenum. It is possible to integrate and systematize a large number of ionic conductors on the basis of the given peculiarities of the crystal structure. Such an approach allows to consider the structure and electrophysical properties of a great number of cation conductors on the common ground, and to mark the concrete ways for searching new ion conducting materials

  11. Modeling Donnan Dialysis Separation for Carboxylic Anion Recovery

    DEFF Research Database (Denmark)

    Prado Rubio, Oscar Andres; Møllerhøj, Martin; Jørgensen, Sten Bay;

    2010-01-01

    dynamic model for transport of multiple ions through an anion exchange membrane is derived based on an irreversible thermodynamics approach. This model accounts for the convective transport of the dissociated and undissociated species in the channels with diffusion and migration across the boundary...... boundary layers and membranes. The model consists of a system of partial differential equations that are solved numerically. The aim of this paper is to corroborate this general model for several monoprotic carboxylic acids reported in the literature. The model reproduces satisfactorily experimental fluxes...

  12. Investigation of Polyacrylate Anion-Exchangers for Separation of Rare Earth Element Complexes with EDTA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The rare earth complexes with EDTA, Ln(edta), show an unusual sequence of affinity for the anion-exchangers. The sorption and chromatographic separation of Y3+ for Nd3+ complexes with EDTA was studied by using the strongly basic gel and macroporous polyacrylate anion-exchangers, Amberlite IRA 458 and Amberlite 958, and the weakly basic gel polyacrylate anion-exchanger, Amberlite IRA-68. The investigations on sorption and separation of rare earth complexes with EDTA on the polyacrylate anion-exchangers applied mainly in the environment protection so far indicate that they can be applied in anionexchange separation of lanthanide complexes with aminopolycarboxylic acids. It was shown that the weakly basic polyacrylate gel anion-exchanger Amberlite IRA-68 is the most effective in purification of Y3+ from Nd3+ in comparison with the strongly basic anion-exchangers of this type.

  13. A bidentate Lewis acid with a telluronium ion as an anion-binding site

    Science.gov (United States)

    Zhao, Haiyan; Gabbaï, François P.

    2010-11-01

    The search for receptors that can selectively capture small and potentially toxic anions in protic media has sparked a renewed interest in the synthesis and anion-binding properties of polydentate Lewis acids. Seeking new paradigms to enhance the anion affinities of such systems, we synthesized a bidentate Lewis acid that contains a boryl and a telluronium moiety as Lewis acidic sites. Anion-complexation studies indicate that this telluronium borane displays a high affinity for fluoride in methanol. Structural and computational studies show that the unusual fluoride affinity of this bidentate telluronium borane can be correlated with the formation of a B-F --> Te chelate motif supported by a strong lone-pair(F) --> σ*(Te-C) donor-acceptor interaction. These results, which illustrate the viability of heavier chalcogenium centres as anion-binding sites, allow us to introduce a novel strategy for the design of polydentate Lewis acids with enhanced anion affinities.

  14. Chloride-Anion-Templated Synthesis of a Strapped-Porphyrin-Containing Catenane Host System.

    Science.gov (United States)

    Brown, Asha; Langton, Matthew J; Kilah, Nathan L; Thompson, Amber L; Beer, Paul D

    2015-12-01

    The synthesis, structure and anion-recognition properties of a new strapped-porphyrin-containing [2]catenane anion host system are described. The assembly of the catenane is directed by discrete chloride anion templation acting in synergy with secondary aromatic donor-acceptor and coordinative pyridine-zinc interactions. The [2]catenane incorporates a three-dimensional, hydrogen-bond-donating anion-binding pocket; solid-state structural analysis of the catenane⋅chloride complex reveals that the chloride anion is encapsulated within the catenane's interlocked binding cavity through six convergent CH⋅⋅⋅⋅Cl and NH⋅⋅⋅Cl hydrogen-bonding interactions and solution-phase (1) H NMR titration experiments demonstrate that this complementary hydrogen-bonding arrangement facilitates the selective recognition of chloride over larger halide anions in DMSO solution. PMID:26508679

  15. Zn-Al LAYERED DOUBLE HYDROXIDE PILLARED BY DIFFERENT DICARBOXYLATE ANIONS

    Directory of Open Access Journals (Sweden)

    S. Gago

    2004-12-01

    Full Text Available Zn-Al layered double hydroxides (LDHs intercalated by terephthalate (TPH and biphenyl-4,4'-dicarboxylate (BPH anions have been synthesized by direct co-precipitation from aqueous solution. The Zn/Al ratio in the final materials was 1.8. The products were characterized by powder X-ray diffraction, thermogravimetric analysis, FTIR and FT Raman spectroscopy, and MAS NMR spectroscopy. The basal spacing for the TPH-LDH intercalate was 14.62 Å, indicating that the guest anions stack to form a monolayer with the aromatic rings perpendicular to the host layers. For the LDH intercalate containing BPH anions, a basal spacing of at least 19.2 Å would be expected if the anions adopted an arrangement similar to that for the TPH anions. The observed spacing was 18.24 Å, suggesting that the anions are tilted slightly with respect to the host layers.

  16. Interpretative optimization of the isocratic ion chromatographic separation of anions

    Directory of Open Access Journals (Sweden)

    Todorović Žaklina N.

    2016-01-01

    Full Text Available Interpretive retention modeling was utilized to optimize the isocratic ion chromatographic (IC separation of the nine anions (formate, fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate, oxalate. The carbonate-bicarbonate eluent was used and separation was done on a Dionex AS14 ion-exchange column. The influence of combined effects of two mobile phase factors, the total eluent concentration (2 - 6 mM and the carbonate/bicaronate ratio from 1:9 to 9:1 (which corespondent to pH range 9.35 - 11.27, on the IC separation was studied. The multiple species analyte/eluent model that takes into account ion-exchange equilibria of the eluent and sample anions was used. In order to estimate the parameters in the model, a non-linear fitting of the retention data, obtained at two-factor three-level experimental design, was applied. To find the optimal conditions in the experimental design, the normalized resolution product as a chromatographic objective function was employed. This criterion includes both the individual peak resolution and the total analysis time. A good agreement between experimental and simulated chromatograms was obtained. [Projekat Ministarstva nauke Republike Srbije, br. III43009

  17. Dynamics of anion-molecule reactions at low energy

    International Nuclear Information System (INIS)

    Anion-molecule reactions must find their way through deeply bound entrance and exit channel complexes separated by a central barrier. This results in low reaction rates and rich dynamics since direct pathways compete with the formation of transient intermediates. In this thesis we examine the probability of proton transfer to a small anion and transient lifetimes of a thermoneutral bimolecular nucleophilic substitution (SN2) reaction at well defined variable temperature down to 8 Kelvin in a multipole trap. The observed strong inverse temperature dependence is attributed to the deficit of available quantum states in the entrance channel at decreasing temperature. Furthermore we investigate scattering dynamics of SN2 reactions at defined relative energy between 0.4 and 10 eV by crossed beam slice imaging. A weakly exothermic reaction with high central barrier proceeds via an indirect, complex-mediated mechanism at low relative energies featuring high internal product excitation in excellent quantitative agreement with a statistical model. In contrast, direct backward scattering prevails for higher energies with product velocities close to the kinematical cutoff. For a strongly exothermic reaction, competing SN2-, dihalide- and proton transfer-channels are explored which proceed by complex mediation for low energy and various rebound-, grazing- and collision induced bond rupture-mechanisms at higher energy. From our data and a collaboration with theory we identify a new indirect roundabout SN2 mechanism involving CH3-rotation. (orig.)

  18. Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films

    Energy Technology Data Exchange (ETDEWEB)

    Arges, Christopher G.; Kambe, Yu; Suh, Hyo Seon; Ocola, Leonidas E.; Nealey, Paul F.

    2016-03-08

    Connecting structure and morphology to bulk transport properties, such as ionic conductivity, in nanostructured polymer electrolyte materials is a difficult proposition because of the challenge to precisely and accurately control order and the orientation of the ionic domains in such polymeric films. In this work, poly(styrene-block-2-vinylpyridine) (PSbP2VP) block copolymers were assembled perpendicularly to a substrate surface over large areas through chemical surface modification at the substrate and utilizing a versatile solvent vapor annealing (SVA) technique. After block copolymer assembly, a novel chemical vapor infiltration reaction (CVIR) technique selectively converted the 2-vinylpyridine block to 2-vinyl n-methylpyridinium (NMP+ X-) groups, which are anion charge carriers. The prepared block copolymer electrolytes maintained their orientation and ordered nanostructure upon the selective introduction of ion moieties into the P2VP block and post ion-exchange to other counterion forms (X- = chloride, hydroxide, etc.). The prepared block copolymer electrolyte films demonstrated high chloride ion conductivities, 45 mS cm(-1) at 20 degrees C in deionized water, the highest chloride ion conductivity for anion conducting polymer electrolyte films. Additionally, straight-line lamellae of block copolymer electrolytes were realized using chemoepitaxy and density multiplication. The devised scheme allowed for precise and accurate control of orientation of ionic domains in nanostructured polymer electrolyte films and enables a platform for future studies that examines the relationship between polymer electrolyte structure and ion transport.

  19. Dynamics of anion-molecule reactions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikosch, J.

    2007-11-15

    Anion-molecule reactions must find their way through deeply bound entrance and exit channel complexes separated by a central barrier. This results in low reaction rates and rich dynamics since direct pathways compete with the formation of transient intermediates. In this thesis we examine the probability of proton transfer to a small anion and transient lifetimes of a thermoneutral bimolecular nucleophilic substitution (S{sub N}2) reaction at well defined variable temperature down to 8 Kelvin in a multipole trap. The observed strong inverse temperature dependence is attributed to the deficit of available quantum states in the entrance channel at decreasing temperature. Furthermore we investigate scattering dynamics of S{sub N}2 reactions at defined relative energy between 0.4 and 10 eV by crossed beam slice imaging. A weakly exothermic reaction with high central barrier proceeds via an indirect, complex-mediated mechanism at low relative energies featuring high internal product excitation in excellent quantitative agreement with a statistical model. In contrast, direct backward scattering prevails for higher energies with product velocities close to the kinematical cutoff. For a strongly exothermic reaction, competing S{sub N}2-, dihalide- and proton transfer-channels are explored which proceed by complex mediation for low energy and various rebound-, grazing- and collision induced bond rupture-mechanisms at higher energy. From our data and a collaboration with theory we identify a new indirect roundabout S{sub N}2 mechanism involving CH{sub 3}-rotation. (orig.)

  20. Functional role of anion channels in cardiac diseases

    Institute of Scientific and Technical Information of China (English)

    Da-yue DUAN; Luis LH LIU; Nathan BOZEAT; Z Maggie HUANG; Sunny Y XIANG; Guan-lei WANG; Linda YE; Joseph R HUME

    2005-01-01

    In comparison to cation (K+, Na+, and Ca2+) channels, much less is currently known about the functional role of anion (Cl-) channels in cardiovascular physiology and pathophysiology. Over the past 15 years, various types of Cl- currents have been recorded in cardiac cells from different species including humans. All cardiac Cl- channels described to date may be encoded by five different Cl- channel genes: the PKA- and PKC-activated cystic fibrosis tansmembrane conductance regulator (CFTR), the volume-regulated ClC-2 and ClC-3, and the Ca2+-activated CLCA or Bestrophin. Recent studies using multiple approaches to examine the functional role of Cl- channels in the context of health and disease have demonstrated that Cl- channels might contribute to: 1) arrhythmogenesis in myocardial injury; 2) cardiac ischemic preconditioning; and 3) the adaptive remodeling of the heart during myocardial hypertrophy and heart failure. Therefore,anion channels represent very attractive novel targets for therapeutic approaches to the treatment of heart diseases. Recent evidence suggests that Cl- channels,like cation channels, might function as a multiprotein complex or functional module.In the post-genome era, the emergence of functional proteomics has necessitated a new paradigm shift to the structural and functional assessment of integrated Cl- channel multiprotein complexes in the heart, which could provide new insight into our understanding of the underlying mechanisms responsible for heart disease and protection.

  1. Diffusion of anions and cations in compacted sodium bentonite

    International Nuclear Information System (INIS)

    The thesis presents the results of studies on the diffusion mechanisms of anions and cations in compacted sodium bentonite, which is planned to be used as a buffer material in nuclear waste disposal in Finland. The diffusivities and sorption factors were determined by tracer experiments. The pore volume accessible to chloride, here defined as effective porosity, was determined as a function of bentonite density and electrolyte concentration in water, and the Stern-Gouy double-layer model was used to explain the observed anion exclusion. The sorption of Cs+ and Sr2+ was studied in loose and compacted bentonite samples as a function of the electrolyte concentration in solution. In order to obtain evidence of the diffusion of exchangeable cations, defined as surface diffusion, the diffusivities of Cs+ and Sr2+ in compacted bentonite were studied as a function of the sorption factor, which was varied by electrolyte concentration in solution. The measurements were performed both by a non-steady state method and by a through-diffusion method. (89 refs., 35 fig., 4 tab.)

  2. A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes

    Science.gov (United States)

    He, Yubin; Pan, Jiefeng; Wu, Liang; Zhu, Yuan; Ge, Xiaolin; Ran, Jin; Yang, Zhengjin; Xu, Tongwen

    2015-08-01

    Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH- conductive anion exchange polyelectrolytes with good alkaline tolerance and excellent dimensional stability. Polymer backbones were grafted with flexible aliphatic chains containing two or three quaternized ammonium groups. The highly flexible and hydrophilic multi-functionalized side chains prefer to aggregate together to facilitate the formation of well-defined hydrophilic-hydrophobic microphase separation, which is crucial for the superior OH- conductivity of 69 mS/cm at room temperature. Besides, the as-prepared AEMs also exhibit excellent alkaline tolerance as well as improved dimensional stability due to their carefully designed polymer architecture, which provide new directions to pursue high performance AEMs and are promising to serve as a candidate for fuel cell technology.

  3. Fibrin solubilizing properties of certain anionic and cationic detergents.

    Science.gov (United States)

    Chakrabarty, S

    1989-08-15

    The fibrinolytic (fibrin dissolving) properties of several anionic, cationic, nonionic and zwitterionic detergents were assessed in an in vitro fibrin agarose assay. Of the 4 anionic detergents tested, only sodium dodecyl sulfate (SDS) was found to be fibrinolytic. SDS was fibrinolytic either in the absence or presence of factor XIII. Four other cationic detergents were found to possess similar fibrinolytic properties. These cationic detergents were cetyltrimethylammonium bromide (CTAB), mix alkyltrimethyl ammonium bromide (MTAB), hexadecyltrimethylammonium bromide (HTAB) and cetylpyridium chloride (CPC). The nonionic (digitonin, triton X-100/tween 20) and zeitterionic (CHAPS, zeittergent 3-08) detergents were not fibrinolytic. Detergents mediated fibrinolysis, unlike that of tissue type plasminogen activator and urokinase, was independent of the presence of plasminogen. Non-detergents such as polyethylene glycol and highly charged compounds such as poly-1-lysine and poly-1-glutamic acid were not fibrinolytic. Fibrinolytic activity was observed for SDS and the cationic detergents at concentrations ranging from 0.1-10 percent. The effects of these fibrinolytic detergents (SDS, CTAB, MTAB, HTAB and CPC) on clot formation and on pre-formed clots were then assessed, using freshly drawn human venous blood. Incorporation of these detergents into blood inhibited the formation of clots in a concentration dependent manner. The detergents were also able to dissolve pre-formed clots in a similar fashion. SDS was found to be most potent in these properties. PMID:2510356

  4. Pulse radiolysis study of the formation and the reactivity of baicalin radical anion, and in comparison with rutin, quercetin and acyrlate ester radical anions in ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Sun Gang [Department of Applied Chemistry, College of Chemical and Molecular Engineering, Peking University, Beijing 100871 (China) and Department of Internal Medicine, Division of Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St Louis, MO 63110 (United States)]. E-mail: gangsun@wustl.edu; Wang Wenfeng [Shanghai Institute of Applied Physics, Academic Sinica, P.O. Box 800-204, Shanghai 201800 (China); Wu Jilan [Department of Applied Chemistry, College of Chemical and Molecular Engineering, Peking University, Beijing 100871 (China)]. E-mail: wangwqchem@pku.edu.cn

    2007-06-15

    The reaction of solvated electrons with baicalin in N{sub 2}-saturated ethanol has been studied by pulse radiolysis. The results show that a solvated electron can add to baicalin and generate a baicalin radical anion with a maximum UV absorbance peak at 360 nm. Its molar extinction coefficient at this wavelength is 1.3x10{sup 4} M{sup -1} cm{sup -1}. The rate constant for the build-up of the baicalin radical anion is 1.3({+-}0.4)x10{sup 10} M{sup -1} s{sup -1}. Decay of the radical anion is induced by a proton transfer reaction and a recombination reaction, which involves a pseudo-first-order reaction with rate constant 2.6({+-}0.4)x10{sup 3} s{sup -1} and a second-order reaction with rate constant 1.3({+-}0.2)x10{sup 9} M{sup -1} s{sup -1}. The effect of acetaldehyde on the decay of the baicalin radical anion was also investigated. Electron transfer between the baicalin radical anion and acetaldehyde was not observed, probably due to the low rate of electron transfer between the baicalin radical anion and acetaldehyde. Reactivity of the rutin, quercetin, baicalin and ethyl acrylate radical anions are also compared.

  5. Investigation of thermally induced anion disorder in fluorites using neutron scattering techniques

    DEFF Research Database (Denmark)

    Hutchings, M T; Clausen, Kurt Nørgaard; Dickens, M H;

    1984-01-01

    Some materials with the fluorite structures show a pronounced specific heat anomaly well below their melting temperature. This anomaly is a consequence of lattice disorder and is associated with the onset of fast-ion conduction. This paper presents the results of a series of experiments in which ...... anion Frenkel interstitials, anion vacancies and relaxed anions has been developed which satisfactorily accounts for the distribution of intensity....

  6. Anion-exchangeable inorganic-organic hybrid materials synthesized without using templates

    Institute of Scientific and Technical Information of China (English)

    XU Xianzhu; SONG Jiangwei; LI Defeng; XIAO Fengshou

    2004-01-01

    Inorganic-organic hybrid materials have been obtained at room temperature in aqueous solution without using the templates of surfactants. The materials are care fully characterized by anion-exchange measurement, elements analysis, X-ray diffraction, and infrared spectroscopy. Notably, the anion-exchange capacity of the samples (3.9 Interestingly, both small and large anions could be easily exchanged into the samples due to the plasticity of the sam pies, along with the phase transition.

  7. Removal of chromium complex dye from aqueous solutions using strongly basic and weakly basic anion exchangers

    OpenAIRE

    Kauspediene, D.; Kazlauskiene E.; Selskiene, A.

    2010-01-01

    Removal of chromium complex dye from aqueous solutions by sorption onto a weakly basic, acrylic matrix anion exchanger Purolite A845 and a strongly basic, polystyrene matrix anion exchanger Purolite A 500P has been investigated under various experimental conditions: the initial dye concentration, pH and temperature. The sorption of chromium complex dye proceeds as a result of miscellaneous interactions between the dye and anion exchanger: ion exchange and physical sorption. The removal effici...

  8. Preparation, Characterization and Adsorption Performance of a Novel Anionic Starch Microsphere

    OpenAIRE

    Yati Yang; Xiuzhi Wei; Peng Sun; Juanmin Wan

    2010-01-01

    Neutral starch microspheres (NSMs) were synthesized by an inverse microemulsion technology with epichlorohydrin as a crosslinker and soluble starch as starting material. Anionic starch microspheres (ASMs) were prepared from NSMs by the secondary polymerization with chloroacetic acid as the anionic etherifying agent. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and laser diffraction particle size analyzer were used to characterize the anionic starch micro...

  9. On the Formation of (Anionic) Excited Helium Dimers in Helium Droplets

    OpenAIRE

    Huber, Stefan E.; Mauracher, Andreas

    2014-01-01

    Metastable atomic and molecular helium anions exhibiting high-spin quartet configurations can be produced in helium droplets via electron impact. Their lifetimes allow detection in mass spectrometric experiments. Formation of atomic helium anions comprises collision-induced excitation of ground state helium and concomitant electron capture. Yet the formation of molecular helium anions in helium droplets has been an unresolved issue. In this work, we explore the interaction of excited helium a...

  10. Modeling the interaction of nitrate anions with ozone and atmospheric moisture

    Institute of Scientific and Technical Information of China (English)

    A. Y. Galashev

    2015-01-01

    The molecular dynamics method is used to investigate the interaction between one–six nitrate anions and water clus-ters absorbing six ozone molecules. The infrared (IR) absorption and reflection spectra are reshaped significantly, and new peaks appear at Raman spectra due to the addition of ozone and nitrate anions to the disperse water system. After ozone and nitrate anions are captured, the average (in frequency) IR reflection coefficient of the water disperse system increased drastically and the absorption coefficient fell.

  11. The remarkable ability of anions to bind dihydrogen.

    Science.gov (United States)

    Della, Therese Davis; Suresh, Cherumuttathu H

    2016-05-25

    The structural features and hydrogen binding affinity of anions F(-), Cl(-), Br(-), OH(-), NH2(-), NO2(-), CN(-), and ClO(-) have been explored at the CCSD(T)/aug-cc-pVTZ//CCSD/6-311++G(d,p) level of coupled cluster theory and the M06L/6-311++G(d,p) level of density functional theory along with a two-point extrapolation to the complete basis set limit and a benchmark study at CCSD(T) and MP2 levels. The coupled cluster, MP2 and DFT methods yield comparable results and show that anions have very high capacity to store hydrogen as the weight percent of H2 in the highest H2-coordinated state of F(-), Cl(-), Br(-), OH(-), NH2(-), NO2(-), CN(-), and ClO(-) is 56.0, 47.6, 33.5, 64.0, 65.4, 41.2, 55.4, and 40.0 wt%, respectively. The CCSD(T)/aug-cc-pVTZ//CCSD/6-311++G(d,p) results are presented for anions coordinated with up to nine or ten H2 molecules, while up to the entire first coordination shell is computed using the M06L method which revealed H2 coordination numbers of 12, 16, 20, 15, 15, 16, 16, and 17, respectively, for F(-), Cl(-), Br(-), OH(-), NH2(-), NO2(-), CN(-), and ClO(-). An increase in the total interaction energy (Eint) and a decrease in the interaction energy per H2 molecule (Eint/H2) with an increase in the number of coordinated H2 molecules are observed. However, the decrease in Eint/H2 is very less and even in the highest coordinated anions, substantially good values of Eint/H2 are observed, viz. 4.24, 2.59, 2.09, 3.32, 3.07, 2.36, 2.31, and 2.63 kcal mol(-1) for F(-), Cl(-), Br(-), OH(-), NH2(-), NO2(-), CN(-), and ClO(-), respectively, which are comparable with the values obtained for complexes with lesser H2 coordination. The stability of the complexes is attributed to the formation of a large number of non-covalent X(-)H bonds as revealed by the identification of bond critical points in the quantum theory of atoms in molecules (QTAIM) analysis. Further, critical features of molecular electrostatic potential (MESP) have been used to correlate the

  12. Novel Fragmentation Pathways of Anionic Adducts of Steroids Formed by Electrospray Anion Attachment Involving Regioselective Attachment, Regiospecific Decompositions, Charge-Induced Pathways, and Ion-Dipole Complex Intermediates

    Science.gov (United States)

    Rannulu, Nalaka S.; Cole, Richard B.

    2012-09-01

    The analysis of several bifunctional neutral steroids, 5-α-pregnane diol (5-α-pregnane-3α-20βdiol), estradiol (3,17α-dihydroxy-1,3,5(10)-estratriene), progesterone (4-pregnene-3,20-dione), lupeol (3β-hydroxy-20(29)-lupene), pregnenolone (5-pregnen-3β-ol-20-one), and pregnenolone acetate (5-pregnen-3β-ol-20-one acetate) was accomplished by negative ion electrospray mass spectrometry (ESI-MS) employing adduct formation with various anions: fluoride, bicarbonate, acetate, and chloride. Fluoride yielded higher abundances of anionic adducts and more substantial abundances of deprotonated molecules compared with other investigated anions. Collision-induced dissociation (CID) of precursor [M + anion]- adducts of these steroids revealed that fluoride adduct [M + F]- precursors first lose HF to produce [M - H]- and then undergo consecutive decompositions to yield higher abundances of structurally-informative product ions than the other tested anions. In addition to charge-remote fragmentations, the majority of CID pathways of estradiol are deduced to occur via charge-induced fragmentation. Most interestingly, certain anions exhibit preferential attachment to a specific site on these bifunctional steroid molecules, which we are calling "regioselective anion attachment." Regioselective anion attachment is evidenced by subsequent regiospecific decomposition. Regioselective attachment of fluoride (and acetate) anions to low (and moderate) acidity functional groups of pregnenolone, respectively, is demonstrated using deuterated compounds. Moreover, the formation of unique intermediate ion-dipole complexes leading to novel fragmentation pathways of fluoride adducts of pregnenolone acetate, and bicarbonate adducts of d4-pregnenolone, are also discussed.

  13. The anionic basis of fluid secretion by the rabbit mandibular salivary gland

    DEFF Research Database (Denmark)

    Case, R M; Hunter, M; Novak, I;

    1984-01-01

    The role played by anions in salivary secretion has been studied in experiments on the isolated, perfused mandibular gland of the rabbit, in which perfusate Cl- and/or HCO3- were replaced by other anions. Replacement of Cl- with Br- had no significant effect on salivary secretion rate, but replac......The role played by anions in salivary secretion has been studied in experiments on the isolated, perfused mandibular gland of the rabbit, in which perfusate Cl- and/or HCO3- were replaced by other anions. Replacement of Cl- with Br- had no significant effect on salivary secretion rate...

  14. Halides with Fifteen Aliphatic C–H···Anion Interaction Sites

    Science.gov (United States)

    Shi, Genggongwo; Aliakbar Tehrani, Zahra; Kim, Dongwook; Cho, Woo Jong; Youn, Il-Seung; Lee, Han Myoung; Yousuf, Muhammad; Ahmed, Nisar; Shirinfar, Bahareh; Teator, Aaron J.; Lastovickova, Dominika N.; Rasheed, Lubna; Lah, Myoung Soo; Bielawski, Christopher W.; Kim, Kwang S.

    2016-07-01

    Since the aliphatic C–H···anion interaction is relatively weak, anion binding using hydrophobic aliphatic C–H (Cali–H) groups has generally been considered not possible without the presence of additional binding sites that contain stronger interactions to the anion. Herein, we report X-ray structures of organic crystals that feature a chloride anion bound exclusively by hydrophobic Cali–H groups. An X-ray structure of imidazolium-based scaffolds using Cali–H···A‑ interactions (A‑ = anion) shows that a halide anion is directly interacting with fifteen Cali–H groups (involving eleven hydrogen bonds, two bidentate hydrogen-bond-type binding interactions and two weakly hydrogen-bonding-like binding interactions). Additional supporting interactions and/or other binding sites are not observed. We note that such types of complexes may not be rare since such high numbers of binding sites for an anion are also found in analogous tetraalkylammonium complexes. The Cali–H···A‑ interactions are driven by the formation of a near-spherical dipole layer shell structure around the anion. The alternating layers of electrostatic charge around the anion arise because the repulsions between weakly positively charged H atoms are reduced by the presence of the weakly negatively charged C atoms connected to H atoms.

  15. Halides with Fifteen Aliphatic C-H···Anion Interaction Sites.

    Science.gov (United States)

    Shi, Genggongwo; Aliakbar Tehrani, Zahra; Kim, Dongwook; Cho, Woo Jong; Youn, Il-Seung; Lee, Han Myoung; Yousuf, Muhammad; Ahmed, Nisar; Shirinfar, Bahareh; Teator, Aaron J; Lastovickova, Dominika N; Rasheed, Lubna; Lah, Myoung Soo; Bielawski, Christopher W; Kim, Kwang S

    2016-01-01

    Since the aliphatic C-H···anion interaction is relatively weak, anion binding using hydrophobic aliphatic C-H (Cali-H) groups has generally been considered not possible without the presence of additional binding sites that contain stronger interactions to the anion. Herein, we report X-ray structures of organic crystals that feature a chloride anion bound exclusively by hydrophobic Cali-H groups. An X-ray structure of imidazolium-based scaffolds using Cali-H···A(-) interactions (A(-) = anion) shows that a halide anion is directly interacting with fifteen Cali-H groups (involving eleven hydrogen bonds, two bidentate hydrogen-bond-type binding interactions and two weakly hydrogen-bonding-like binding interactions). Additional supporting interactions and/or other binding sites are not observed. We note that such types of complexes may not be rare since such high numbers of binding sites for an anion are also found in analogous tetraalkylammonium complexes. The Cali-H···A(-) interactions are driven by the formation of a near-spherical dipole layer shell structure around the anion. The alternating layers of electrostatic charge around the anion arise because the repulsions between weakly positively charged H atoms are reduced by the presence of the weakly negatively charged C atoms connected to H atoms. PMID:27444513

  16. Reillex/trademark/ HPQ: A new, macroporous polyvinylpyridine resin for separating plutonium using nitrate anion exchange

    International Nuclear Information System (INIS)

    Anion exchange in nitric acid is the major aqueous process used to recover and purify plutonium from impure scrap materials. Most strong-base anion exchange resins incorporate a styrene-divinylbenzene copolymer. A newly available, macroporous anion exchange resin based on a copolymer of 1-methyl-4-vinylpyridine and divinylbenzene has been evaluated. Comparative data for Pu(IV) sorption kinetics and capacity are presented for this new resin and two other commonly used anion exchange resins. The new resin offers high capacity and rapid sorption kinetics for Pu(IV) from nitric acid, as well as greater stability to chemical and radiolytic degradation. 8 refs., 12 figs

  17. A colorimetric and fluorescence enhancement anion probe based on coumarin compounds.

    Science.gov (United States)

    Zhao, Limin; Liu, Ge; Zhang, Baofeng

    2016-12-01

    In this paper, anion probe 1 was designed and synthesized by using phenprocoumon containing acyl hydrazine with p-nitro azo salicylaldehyde reaction Dickson et al. (2008) Dickson et al. (2008) [1]. In the anion probe 1, the nitro moiety is a signaling group and the phenolic hydroxyl moiety is anion binding site. Then the anion probe 1 was characterized by mass spectra (MS) and infrared spectra (IR). The binding properties of the anion probe 1 for anions such as F(-), AcO(-), H2PO4(-), OH(-), Cl(-), Br(-) and I(-) were investigated by ultraviolet-visible (UV-Vis) spectra and fluorescence spectra Shao et al. (2008) Shao et al. (2008) [2]. Furthermore, the color of anion probe 1 after addition of F(-), AcO(-), H2PO4(-) and OH(-) in DMSO changed from yellow to blue, while no obvious color changes were observed by addition of other tested anions. Accordingly, the anion probe 1 could sense visually F(-), AcO(-), H2PO4(-) and OH(-) without resorting to any spectroscopic instrumentation Amendola et al. (2010) Amendola et al. (2010) [3]. PMID:27323317

  18. A photoelectron spectroscopic and computational study of the o-dicarbadodecaborane parent anion.

    Science.gov (United States)

    Zhang, Xinxing; Bowen, Kit

    2016-06-14

    We report a combined photoelectron spectroscopic and computational study of the o-dicarbadodecaborane (o-carborane) parent anion, (C2B10H12)(-). Previous studies that focused on the electrophilic nature of o-carborane led to tantalizing yet mixed results. In our study, we confirmed that o-carborane does in fact form a parent anion and that it has considerable stability. This anion is an isomer ("Anion iso 2") where unlike in neutral o-carborane, the two carbon atoms are not bound. PMID:27306011

  19. Expression and function of renal and hepatic organic anion transporters in extrahepatic cholestasis

    Institute of Scientific and Technical Information of China (English)

    Anabel Brandoni; María Herminia Hazelhoff; Romina Paula Bulacio; Adriana Mónica Torres

    2012-01-01

    Obstructive jaundice occurs in patients suffering from cholelithiasis and from neoplasms affecting the pancreas and the common bile duct.The absorption,distribution and elimination of drugs are impaired during this pathology.Prolonged cholestasis may alter both liver and kidney function.Lactam antibiotics,diuretics,non-steroidal anti-inflammatory drugs,several antiviral drugs as well as endogenous compounds are classified as organic anions.The hepatic and renal organic anion transport pathways play a key role in the pharmacokinetics of these compounds.It has been demonstrated that acute extrahepatic cholestasis is associated with increased renal elimination of organic anions.The present work describes the molecular mechanisms involved in the regulation of the expression and function of the renal and hepatic organic anion transporters in extrahepatic cholestasis,such as multidrug resistanceassociated protein 2,organic anion transporting polypeptide 1,organic anion transporter 3,bilitranslocase,bromosulfophthalein/bilirubin binding protein,organic anion transporter 1 and sodium dependent bile salt transporter.The modulation in the expression of renal organic anion transporters constitutes a compensatory mechanism to overcome the hepatic dysfunction in the elimination of organic anions.

  20. Synthesis of the Anionic Fluororeceptors and Recognition Property for α,ω-Dicarboxylate

    Institute of Scientific and Technical Information of China (English)

    HE,Yong-Bing; WU,Jin-Long; MENG,Ling-Zhi; QIN,Hai-Juan

    2004-01-01

    @@ Anions, especially dicarboxylates, play an important role in chemical and biological processes,[1] dicarboxylates are critical components of numerous metabolic processes including, for instance, the citric acid and glyoxylate cycles.[1a]They also play an important role in the generation of high-energy phosphate bonds and in the biosynthesis of important intermediates.[1b] To date, several receptors containing different functional groups for selective binding of dicarboxylate anions have been reported.[2,3] However, the sensors based on the fluorescence emission for dicarboxylate anions are still rare.3 In this paper, we report the synthesis and binding properties of two new neutral anion receptors (1 and 2).

  1. A photoelectron spectroscopic and computational study of the o-dicarbadodecaborane parent anion

    Science.gov (United States)

    Zhang, Xinxing; Bowen, Kit

    2016-06-01

    We report a combined photoelectron spectroscopic and computational study of the o-dicarbadodecaborane (o-carborane) parent anion, (C2B10H12)-. Previous studies that focused on the electrophilic nature of o-carborane led to tantalizing yet mixed results. In our study, we confirmed that o-carborane does in fact form a parent anion and that it has considerable stability. This anion is an isomer ("Anion iso 2") where unlike in neutral o-carborane, the two carbon atoms are not bound.

  2. Formation reaction mechanisms of hydroxide anions from Mg(OH)2 layers

    International Nuclear Information System (INIS)

    Highlights: • Mg(OH)2 hydroxide anion migrates to the surface thus producing an adsorbed free hydroxide anion. • Orbital contributions from adsorbed free hydroxide anion dominate the shape of total DOS in the region near the Fermi level. • The hydroxide anion formation reaction in Mg(OH)2 from Mg(OH)2 dissociation is slower than the formation from H2O dissociation. • Formation of hydroxide anions in a layered hydroxide would involve reaction of H2O molecules with layer hydroxide anions. - Abstract: DFT calculations with periodic boundary conditions were used to study two formation reaction mechanisms of adsorbed free hydroxide anions on the surface of the brucite, Mg(OH)2. In the first mechanism, we investigated the migration of a hydroxide anion present in the structure of Mg(OH)2 to the layer surface. In the second, a mechanism composed of three elementary reactions was examined for the reaction of H2O molecules with the brucite layer surface. The result in both mechanisms is the formation of hydroxide anions and a hydroxide vacancy in the positively charged Mg(OH)2 layer. The global reaction is the same in both cases and the computed Gibbs free energy variation equals 37.5 kcal/mol at room temperature. The reaction barrier for the formation of hydroxide anion on Mg(OH)2 surface from H2O dissociation (27.6 kcal/mol) is lower than the reaction barrier for the formation of hydroxide anions from Mg(OH)2 dissociation (43.2 kcal/mol)

  3. "Like-charge attraction" between anionic polyelectrolytes: molecular dynamics simulations.

    Science.gov (United States)

    Molnar, Ferenc; Rieger, Jens

    2005-01-18

    "Like-charge attraction" is a phenomenon found in many biological systems containing DNA or proteins, as well as in polyelectrolyte systems of industrial importance. "Like-charge attraction" between polyanions is observed in the presence of mobile multivalent cations. At a certain limiting concentration of cations, the negatively charged macroions cease to repel each other and even an attractive force between the anions is found. With classical molecular dynamics simulations it is possible to elucidate the processes that govern the attractive behavior with atomistic resolution. As an industrially relevant example we study the interaction of negatively charged carboxylate groups of sodium polyacrylate molecules with divalent cationic Ca2+ counterions. Here we show that Ca2+ ions initially associate with single chains of polyacrylates and strongly influence sodium ion distribution; shielded polyanions approach each other and eventually "stick" together (precipitate), contrary to the assumption that precipitation is initially induced by intermolecular Ca2+ bridging. PMID:15641856

  4. Mechanism and kinetics for scavenging superoxide anion by progesterone

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The chemical reaction of progesterone with superoxide anion in 0.1 mol/L NaHCO3 medium is studied by polarography. Differing from the indirect inhibition of generation by synthesized glucocorticoids in mechanism, the function that progesterone scavenges is ascribed to that directly oxidizes the C == C double bond conjugated with the carbonyl moiety of progesterone molecule to a free radical, and then is reduced to H2O2. The result obtained in this work gives new evidence for biomedical research. The equation of rate constant of the oxidization reaction is de-duced, and the apparent rate constant obtained is 308 L·mol-1·s-1.

  5. Vertical ionization energies of halogen anions in solution

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the constrained equilibrium state theory,the nonequilibrium solvation energy is derived in the framework of the continuum model.The formula for spectral shift and vertical ionization energy are deduced for a single sphere cavity with the point charge assumption.The new model is adopted to investigate the vertical ionization for halogen atomic and molecular anions X(X = Cl,Br,I,Cl2,Br2,I2) in aqueous solution.According to the calculation using the CCSD-t/aug-cc-pVQZ method in vacuum,our final estimated vertical ionization energies in solution are very close to the experimental observations,while the traditional nonequilibrium solvation theory overestimates these vertical ionization energies.

  6. UNCERTAINTIES OF ANION AND TOC MEASUREMENTS AT THE DWPF LABORATORY

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, T.

    2011-04-07

    The Savannah River Remediation (SRR) Defense Waste Processing Facility (DWPF) has identified a technical issue related to the amount of antifoam added to the Chemical Process Cell (CPC). Specifically, due to the long duration of the concentration and reflux cycles for the Sludge Receipt and Adjustment Tank (SRAT), additional antifoam has been required. The additional antifoam has been found to impact the melter flammability analysis as an additional source of carbon and hydrogen. To better understand and control the carbon and hydrogen contributors to the melter flammability analysis, SRR's Waste Solidification Engineering (WSE) has requested, via a Technical Task Request (TTR), that the Savannah River National Laboratory (SRNL) conduct an error evaluation of the measurements of key Slurry Mix Evaporator (SME) anions. SRNL issued a Task Technical and Quality Assurance Plan (TTQAP) [2] in response to that request, and the work reported here was conducted under the auspices of that TTQAP. The TTR instructs SRNL to conduct an error evaluation of anion measurements generated by the DWPF Laboratory using Ion Chromatography (IC) performed on SME samples. The anions of interest include nitrate, oxalate, and formate. Recent measurements of SME samples for these anions as well as measurements of total organic carbon (TOC) were provided to SRNL by DWPF Laboratory Operations (Lab OPS) personnel for this evaluation. This work was closely coordinated with the efforts of others within SRNL that are investigating the Chemical Process Cell (CPC) contributions to the melter flammability. The objective of that investigation was to develop a more comprehensive melter flammability control strategy that when implemented in DWPF will rely on process measurements. Accounting for the uncertainty of the measurements is necessary for successful implementation. The error evaluations conducted as part of this task will facilitate the integration of appropriate uncertainties for the

  7. Benzimidazole-derived anion for lithium-conducting electrolytes

    Science.gov (United States)

    Niedzicki, Leszek; Oledzki, Piotr; Bitner, Anna; Bukowska, Maria; Szczecinski, Przemyslaw

    2016-02-01

    In this work we announce new lithium salt of 5,6-dicyano-2-(trifluoromethyl)benzimidazolide (LiTDBI) designed for application in lithium conductive electrolytes. It was synthesized and completely characterized by NMR techniques. Studies show salt's thermal stability up to 270 °C and electrochemical stability in liquid solvents up to +4.7 V vs. metallic lithium anode. Basic characterization of electrolytes made with this salt show conductivity over 1 mS cm-1 and unusually high transference number at high concentrations (0.74 in EC:DMC 1:2 ratio mixture) along with low onset of conductivity peak. As a final proof of concept, cycling in half-cell was performed and electrolyte based on LiTDBI showed perfect capacity retention. Such properties show remarkable progress in creating efficient lithium-conducting electrolytes with use of weakly-coordinating anions.

  8. The removal of anionic surfactants from water in coagulation process.

    Science.gov (United States)

    Kaleta, Jadwiga; Elektorowicz, Maria

    2013-01-01

    This paper presents the results of a laboratory study on the effectiveness of the coagulation process in removing surfactants from water. The application of traditional coagulants (aluminium sulfate and iron chlorides) has not brought satisfactory results, the reduction in anionic surfactant (AS) content reached 7.6% and 10%, respectively. Adding cationic polyelectrolyte (Zetag-50) increased the removal efficiency to 24%. Coagulation using a polyelectrolyte alone proved to be more efficient, the reduction in surfactant content fluctuated at a level of about 50%. Complete surfactant removal was obtained when powdered activated carbon was added 5 minutes before the basic coagulant to the coagulation process. The efficiency of surfactant coagulation also increased after the application of powdered clinoptilolite, but to a smaller degree. Then the removal of AS was found to be improved by dosing powdered clinoptilolite simultaneously or with short delay after the addition of the basic coagulant. PMID:23837351

  9. Experimental studies of single-photon photodetachment of atomic anions

    Science.gov (United States)

    Duvvuri, Srividya S.

    Laser photodetachment electron spectroscopy (LPES) has been used to study the structure of the terbium anion. The data was analyzed assuming that the terbium anion forms in dysprosium-like states. Using this assumption, the electron affinity of Tb([Xe]4f96s 2 6 Ho15/2 ) equals 1.98 +/- 0.10 eV, and the ground state of the terbium anion is assigned to the Dy-like Tb-([Xe]4f 106s2 5I 8) electronic configuration. At lust two bound excited states of Tb - are also evident in the photoelectron kinetic energy spectra, with binding energies of 0.449 +/- 0.01 and 1.67 +/- 0.07 eV relative to the Tb(6 Ho15/2 ) ground state. The energy scale of each Tb- photoelectron spectrum way calibrated using reference photoelectron peaks from 12 C-, 16O- and 23Na-, which have well known binding energies [1]. Photoelectron angular distribution measurements following the single-photon photodetachment of the lanthanide anions Tb- and Lu - are also presented. The asymmetry parameters were determined from the non-linear least-square fits of the photoelectron yields as a function of the angle between the photon polarization vector and the photoelectron momentum vector of the collected photoelectrons. The measurements indicated the single-photon photodetachment process hnu + Tb -([Xe]4f106s 2 5I8) → Tb([Xe]4 f96s2 6) Ho15/2 + e - has beta values of 1.51 +/- 0.08 and 1.35 +/- 0.08 at wavelengths of 514.5 and 488 nm, respectively. For Lu -, the fine-structure resolved photodetachment process hnu +Lu-([Xe]4f146s 26p5d 1D 2) → Lu([Xe]4f145 d6s2 2D 3/2) + e-, has been measured at wavelength of 532 nm yielding beta = 0.8 +/- 0.1, supporting the assertion that Lu - forms via the attachment of a 6p-electron to the neutral Lu atom [2]. Finally, photodetachment cross sections and the angular distributions of photo-electrons produced by the single-photon detachment of the Fe - and Cu- have also been measured at discrete visible photon wavelengths. From the measured photodetachment cross sections, the

  10. Porphyrin Analogues of a Trityl Cation and Anion.

    Science.gov (United States)

    Kato, Kenichi; Kim, Woojae; Kim, Dongho; Yorimitsu, Hideki; Osuka, Atsuhiro

    2016-05-17

    Porphyrin-stabilized meso- or β-carbocations were generated upon treatment of the corresponding bis(4-tert-butylphenyl)porphyrinylcarbinols with trifluoroacetic acid (TFA). Bis(4-tert-butylphenyl)porphyrinylcarbinols were treated with TFA to generate the corresponding carbocations stabilized by a meso- or β-porphyrinyl group. The meso-porphyrinylmethyl carbocation displayed more effective charge delocalization with decreasing aromaticity compared with the β-porphyrinylmethyl carbocation. A propeller-like porphyrin trimer, tris(β-porphyrinyl)carbinol, was also synthesized and converted to the corresponding cation that displayed a more intensified absorption reaching over the NIR region. meso-Porphyrinylmethyl carbanion was generated as a stable species upon deprotonation of bis(4-tert-butylphenyl)(meso-porphyrinyl)methane with potassium bis(trimethylsilyl)amide (KHMDS) and [18]crown-6, whereas β-porphyrinylmethyl anions were highly unstable. PMID:26991021

  11. Anion formation in sputter ion sources by neutral resonant ionization

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, J. S., E-mail: johnsvogel@yahoo.com [University of California, 8300 Feliz Creek Dr., Ukiah, California 95482 (United States)

    2016-02-15

    Focused Cs{sup +} beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm{sup 2} C{sup −} current density compared to the 20 μA/mm{sup 2} from a 1 mm recess.

  12. Preparation of anionic polyurethane nanoparticles and blood compatible behaviors.

    Science.gov (United States)

    Zhu, Qinshu; Wang, Yan; Zhou, Min; Mao, Chun; Huang, Xiaohua; Bao, Jianchun; Shen, Jian

    2012-05-01

    The anionic polyurethane nanoparticles (APU-NPs) were obtained by an emulsion polymerization method. It was found that the average size of the prepared APU-NPs is about 84 nm, and the APU-NPs have zeta-potential of -38.9 mV. The bulk characterization of synthesized APU-NPs was investigated by FTIR. The blood compatibility of APU-NPs was characterized by in vitro for coagulation tests, complement activation, platelet activation, cytotoxicity experiments, and hemolysis assay. The results showed that the APU-NPs synthesized in this paper are blood compatible with low level of cell cytotoxicity, and the results were significant for their potential use in vivo. PMID:22852346

  13. Removal of both cationic and anionic contaminants by amphoteric starch.

    Science.gov (United States)

    Peng, Huanlong; Zhong, Songxiong; Lin, Qintie; Yao, Xiaosheng; Liang, Zhuoying; Yang, Muqun; Yin, Guangcai; Liu, Qianjun; He, Hongfei

    2016-03-15

    A novel amphoteric starch incorporating quaternary ammonium and phosphate groups was applied to investigate the efficiency and mechanism of cationic and anionic contaminant treatment. Its flocculation abilities for kaolin suspension and copper-containing wastewater were evaluated by turbidity reduction and copper removal efficiency, respectively. And the kinetics of formation, breakage and subsequent re-formation of aggregates were monitored using a Photometric Dispersion Analyzer (PDA) and characterized by flocculation index (FI). The results showed that amphoteric starch possessed the advantages of being lower-dosages-consuming and being stronger in shear resistance than cationic starch, and exhibited a good flocculation efficiency over a wide pH range from 3.0 to 11.0. PMID:26794754

  14. Anion formation in sputter ion sources by neutral resonant ionization

    International Nuclear Information System (INIS)

    Focused Cs+ beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm2 C− current density compared to the 20 μA/mm2 from a 1 mm recess

  15. Adsorption of Anionic Dyes onto Chitosan-modified Diatomite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ge-shan; XUE Hong-hai; TANG Xiao-jian; PENG Fei; KANG Chun-li

    2011-01-01

    The purpose of this work is to study the possibility of anionic dyes Reactive Red M-8B(RR)and Direct Green B(DG)adsorbed on chitosan-modified diatomite.The characteristics of adsorbent,adsorption isotherms and the influence of adsorption time,temperature and pH were researched in this work.The results show that the modified diatomite had a much better adsorption capability than the natural diatomite.The adsorption capacities of chitosan-modified diatomite for RR and DG were 94.46 and 137.0 mg/g,respectively.Both adsorption time and adsorption temperature provided a positive effect on the dye adsorption.Within the experimental pH range,the adsorbance was enhanced at lower pH but reduced sharply at high pH.On the basis of the experimental results and discussion,electrostatic attraction is considered as the main mechanism of this chemisorption.

  16. Alkaline direct alcohol fuel cells using an anion exchange membrane

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Koji; Iriyama, Yasutoshi; Abe, Takeshi; Ogumi, Zempachi [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Matsuoka, Masao [Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan)

    2005-10-04

    Alkaline direct alcohol fuel cells using an OH-form anion exchange membrane and polyhydric alcohols were studied. A high open circuit voltage of ca. 800mV was obtained for a cell using Pt-Ru/C (anode) and Pt/C (cathode) at 323K, which was about 100-200mV higher than that for a DMFC using Nafion{sup R}. The maximum power densities were in the order of ethylene glycol>glycerol>methanol>erythritol>xylitol. Silver catalysts were used as a cathode catalyst to fabricate alkaline fuel cells, since silver catalyst is almost inactive in the oxidation of polyhydric alcohols. Alkaline direct ethylene glycol fuel cells using silver as a cathode catalyst gave excellent performance because higher concentrations of fuel could be supplied to the anode. (author)

  17. Anion exchange kinetics of uranium in sulphate media

    International Nuclear Information System (INIS)

    Experiments have shown that the sorption of uranium from acidic sulphate solutions onto strong base-anion exchange resins is particle diffusion controlled in the uranium concentration range 0.0001 to 0.004 M. A simplified diffusion model, based on Fick's Law, fits the kinetic data at each concentration. The rate of sorption falls significantly at lowered solution concentration. This corresponds with a lowered equilibrium loading of uranium and can be predicted with the Nernst-Planck equations using the measured self diffusion coefficient of uranium (1.65 x 10-8 cm2/s) and sulphate ions. The importance of this lowering of uranium sorption on the design of ion exchange equipment is stressed. (author)

  18. Preparation of anionic polyurethane nanoparticles and blood compatible behaviors.

    Science.gov (United States)

    Zhu, Qinshu; Wang, Yan; Zhou, Min; Mao, Chun; Huang, Xiaohua; Bao, Jianchun; Shen, Jian

    2012-05-01

    The anionic polyurethane nanoparticles (APU-NPs) were obtained by an emulsion polymerization method. It was found that the average size of the prepared APU-NPs is about 84 nm, and the APU-NPs have zeta-potential of -38.9 mV. The bulk characterization of synthesized APU-NPs was investigated by FTIR. The blood compatibility of APU-NPs was characterized by in vitro for coagulation tests, complement activation, platelet activation, cytotoxicity experiments, and hemolysis assay. The results showed that the APU-NPs synthesized in this paper are blood compatible with low level of cell cytotoxicity, and the results were significant for their potential use in vivo.

  19. Surface electrochemistry of CO on Pt(111): Anion Effects

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, N.M.; Lucas, C.A.; Rodes, A.; Stamenkovic, V.; Ross, P.N.

    2001-07-30

    In-situ studies of CO adsorption by surface x-ray scattering (SXS) and Fourier transform infrared (FTIR) spectroscopy techniques are used to create the link between the macroscopic kinetic rates of CO oxidation and the microscopic level of understanding the structure/site occupancy of CO on Pt(111). A remarkable difference in activity was observed between alkaline and acid solutions. In alkaline solution the oxidation of CO proceeds at low overpotential (<0.2 V) by the surface reaction between the adsorbed CO and OH, the latter forming selectively in the hydrogen underpotential potential region at defect sites. In acid solution these sites are blocked by specific adsorption of anions, and consequently in a solution containing Br{sup -} the ignition potential is shifted positively by 0.6 V. Anions of supporting electrolytes also have dramatic effects on both the potential range of stability and the domain size of the p(2x2)-3CO structure which is formed at 0.05 V. The stability/domain size of this structure increases from KOH (ca. 30 {angstrom} between 0.05 < E < 0.3V), to HClO{sub 4} (ca. 140 {angstrom} between 0.05 < E < 0.6V) to HClO{sub 4} + Br{sup -} (ca 350 {angstrom} between 0.05 < E < 0.8V). The larger the ordered domains of the p(2x2)-CO{sub ad} structure are, the less active the surface is towards CO oxidation.

  20. Optimized anion exchange membranes for vanadium redox flow batteries.

    Science.gov (United States)

    Chen, Dongyang; Hickner, Michael A; Agar, Ertan; Kumbur, E Caglan

    2013-08-14

    In order to understand the properties of low vanadium permeability anion exchange membranes for vanadium redox flow batteries (VRFBs), quaternary ammonium functionalized Radel (QA-Radel) membranes with three ion exchange capacities (IECs) from 1.7 to 2.4 mequiv g(-1) were synthesized and 55-60 μm thick membrane samples were evaluated for their transport properties and in-cell battery performance. The ionic conductivity and vanadium permeability of the membranes were investigated and correlated to the battery performance through measurements of Coulombic efficiency, voltage efficiency and energy efficiency in single cell tests, and capacity fade during cycling. Increasing the IEC of the QA-Radel membranes increased both the ionic conductivity and VO(2+) permeability. The 1.7 mequiv g(-1) IEC QA-Radel had the highest Coulombic efficiency and best cycling capacity maintenance in the VRFB, while the cell's voltage efficiency was limited by the membrane's low ionic conductivity. Increasing the IEC resulted in higher voltage efficiency for the 2.0 and 2.4 mequiv g(-1) samples, but the cells with these membranes displayed reduced Coulombic efficiency and faster capacity fade. The QA-Radel with an IEC of 2.0 mequiv g(-1) had the best balance of ionic conductivity and VO(2+) permeability, achieving a maximum power density of 218 mW cm(-2) which was higher than the maximum power density of a VRFB assembled with a Nafion N212 membrane in our system. While anion exchange membranes are under study for a variety of VRFB applications, this work demonstrates that the material parameters must be optimized to obtain the maximum cell performance. PMID:23799776

  1. Optimized anion exchange membranes for vanadium redox flow batteries.

    Science.gov (United States)

    Chen, Dongyang; Hickner, Michael A; Agar, Ertan; Kumbur, E Caglan

    2013-08-14

    In order to understand the properties of low vanadium permeability anion exchange membranes for vanadium redox flow batteries (VRFBs), quaternary ammonium functionalized Radel (QA-Radel) membranes with three ion exchange capacities (IECs) from 1.7 to 2.4 mequiv g(-1) were synthesized and 55-60 μm thick membrane samples were evaluated for their transport properties and in-cell battery performance. The ionic conductivity and vanadium permeability of the membranes were investigated and correlated to the battery performance through measurements of Coulombic efficiency, voltage efficiency and energy efficiency in single cell tests, and capacity fade during cycling. Increasing the IEC of the QA-Radel membranes increased both the ionic conductivity and VO(2+) permeability. The 1.7 mequiv g(-1) IEC QA-Radel had the highest Coulombic efficiency and best cycling capacity maintenance in the VRFB, while the cell's voltage efficiency was limited by the membrane's low ionic conductivity. Increasing the IEC resulted in higher voltage efficiency for the 2.0 and 2.4 mequiv g(-1) samples, but the cells with these membranes displayed reduced Coulombic efficiency and faster capacity fade. The QA-Radel with an IEC of 2.0 mequiv g(-1) had the best balance of ionic conductivity and VO(2+) permeability, achieving a maximum power density of 218 mW cm(-2) which was higher than the maximum power density of a VRFB assembled with a Nafion N212 membrane in our system. While anion exchange membranes are under study for a variety of VRFB applications, this work demonstrates that the material parameters must be optimized to obtain the maximum cell performance.

  2. Enhanced DOC removal using anion and cation ion exchange resins.

    Science.gov (United States)

    Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

    2016-01-01

    Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. PMID:26624231

  3. Anion release and uptake kinetics: structural changes of layered 2-dimensional ZnNiHN upon uptake of acetate and chlorinated acetate anions.

    Science.gov (United States)

    Machingauta, Cleopas; Hossenlopp, Jeanne M

    2013-12-01

    X-ray diffraction and UV-vis spectroscopy were used for the investigation of ion exchange reaction kinetics of nitrates with acetate (Ac), chloro acetate (ClAc), dichloro acetate (dClAc) and trichloro acetate (tClAc) anions, using zinc nickel hydroxy nitrate (ZnNiHN) as the exchange precursor. The exchange reactions conducted at 24, 30, 40 and 50°C revealed that rate constants were inversely related to the calculated anion electronic spatial extent (ESE), while a direct relationship between rate constants and the average oxygen charges was observed. Temporal solid phase structural transformations were shown to be affected by the nature of the guest anions. The amount of nitrates released into solution has been shown to decrease as the guest anions became more chlorinated. Use of isoconversional approach revealed that activation energies changed significantly with α during dClAc intercalation than for the other anions. The topotactic intercalation of the guest anions, except dClAc, followed the Avrami-Erofe'ev kinetic model for the entire reaction progress. PMID:24054447

  4. A new family of anionic organic–inorganic hybrid doughnut-like nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuxiu; Gao, Wen-Yang; Wojtas, Lukasz; Zhang, Zhenjie; Zaworotko, Michael J. (Limerick); (USF)

    2015-06-15

    A family of soluble organic–inorganic hybrid doughnut-like anions, hydoughnuts, has been prepared by the self-assembly of polyoxovanadate anions and 1,3-benzenedicarboxylate (bdc) linkers. Derivatives of the parent hydoughnut, [(V₄O₈Cl)₄(bdc)₈]⁴⁻, can be obtained by changing the counter-ion or by using a variant of bdc.

  5. Ureaphosphanes as hybrid, anionic or supramolecular bidentate ligands for asymmetric hydrogenation reactions

    NARCIS (Netherlands)

    Meeuwissen, J.; Detz, R.; Sandee, A. J.; de Bruin, B.; Siegler, M. A.; Spek, A.L.; Reek, J.N.H.

    2010-01-01

    We report the coordination behavior of ureaphosphane ligand 1-[2-(diphenylphosphanyl)ethyl]-3-phenylurea (L1) towards different rhodium precursor complexes. Depending on the nature of the anion and the ligand/metal ratio, L1 acts either as a hybrid P,O-coordinating chelate, as an anionic P,N-coordin

  6. The saccharinate anion: a versatile and fascinating ligand in coordination chemistry

    Directory of Open Access Journals (Sweden)

    Enrique J. Baran

    2005-03-01

    Full Text Available The saccharinate anion, obtained by deprotonation of the N-H moiety of saccharin (o-sulfobenzimide is a very versatile and polyfunctional ligand in coordination chemistry. In this review the different forms of metal-to-ligand interactions involving this anion and some other coordination peculiarities are briefly discussed on the basis of some selected examples.

  7. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.

    2013-08-07

    A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt 2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation. 2013 The Royal Society of Chemistry.

  8. Preassembly-driven ratiometric sensing of H2PO4(-) anions in organic and aqueous environments.

    Science.gov (United States)

    Gong, Wei-tao; Na, Duo; Fang, Le; Mehdi, Hassan; Ning, Gui-ling

    2015-02-21

    Gemini surfactant-like receptor is designed and synthesized. The special preassembly phenomenon of in a nonpolar solvent facilitates the novel ratiometric fluorescence sensing of H2PO4(-)via an anion-induced reassembly process in organic solvents and an anion-induced disassembly process in water. PMID:25563510

  9. Effect of divalent anions on photodegradation kinetics and pathways of riboflavin in aqueous solution.

    Science.gov (United States)

    Ahmad, Iqbal; Ahmed, Sofia; Sheraz, Muhammad Ali; Vaid, Faiyaz H M; Ansari, Izhar A

    2010-05-10

    The present investigation is based on a study of the effect of buffer and non-buffer divalent anions (phosphate, sulphate, tartrate, succinate, malonate) on the kinetics, product distribution and photodegradation pathways of riboflavin (RF) at pH 6.0-8.0. RF solutions (5x10(-5)M) were photodegraded in the presence of divalent anions (0.2-1.0M) using a visible light source and the photoproducts, cyclodehydroriboflavin (CDRF), formylmethylflavin (FMF), lumichrome (LC) and lumiflavin (LF) were assayed by a specific multicomponent spectrophotometric method. RF degradation in the presence of divalent anions follows parallel first-order kinetics to give CDRF and LC as the final products through photoaddition and photoreduction reactions, respectively. The divalent anion-catalysed CDRF formation is affected in the order: phosphate>sulphate>tartrate>succinate>malonate, showing maximum activity of the anions around pH 7. The divalent anions cause deviation of the photoreduction pathway in favour of the photoaddition pathway to form CDRF. The first- and second-order rate constants for the reactions involved in the photodegradation of RF have been determined and the rate-pH profiles and pathway relationships discussed. The catalytic activity of the divalent anions appears to be a function of the relative strength and chemical reactivity of the RF-divalent anion complex acting as a mediator in the photoaddition reaction.

  10. Colorimetric sensing of anions in water using ratiometric indicator-displacement assay.

    Science.gov (United States)

    Feng, Liang; Li, Hui; Li, Xiao; Chen, Liang; Shen, Zheng; Guan, Yafeng

    2012-09-19

    The analysis of anions in water presents a difficult challenge due to their low charge-to-radius ratio, and the ability to discriminate among similar anions often remains problematic. The use of a 3×6 ratiometric indicator-displacement assay (RIDA) array for the colorimetric detection and identification of ten anions in water is reported. The sensor array consists of different combinations of colorimetric indicators and metal cations. The colorimetric indicators chelate with metal cations, forming the color changes. Upon the addition of anions, anions compete with the indicator ligands according to solubility product constants (K(sp)). The indicator-metal chelate compound changes color back dramatically when the competition of anions wins. The color changes of the RIDA array were used as a digital representation of the array response and analyzed with standard statistical methods, including principal component analysis and hierarchical clustering analysis. No confusion or errors in classification by hierarchical clustering analysis were observed in 44 trials. The limit of detection was calculated approximately, and most limits of detections of anions are well below μM level using our RIDA array. The pH effect, temperature influence, interfering anions were also investigated, and the RIDA array shows the feasibility of real sample testing.

  11. Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins

    International Nuclear Information System (INIS)

    Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of Kd values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins

  12. Effect of Several Anions on Fe-Based Catalyst for Fischer-Tropsch Synthesis

    Institute of Scientific and Technical Information of China (English)

    Jingchang Zhang; Xuehua Guo; Weiliang Cao

    2007-01-01

    The influence of several anions on Fe-based Fischer-Tropsch catalyst, used in the synthesis of light olefins from synthesis gas, was studied. The results indicated that the addition of anions resulted in the reduction of catalytic activity. When the anion content in the catalyst was 500 ppm, the influence of different anions on the catalysis activity was as follows: S2->Cl->SO42->NO3-. The addition of S2- improved the selectivity of total hydrocarbons in the products, and Cl- reduced this selectivity but increased the olefin content in the total hydrocarbons at the same time. When the contents of S2- and Cl- in the catalyst were less than 50 ppm, their influence could be ignored. The XRD results indicated that the addition of anions reduced the contents of a-Fe and Fe3C, which were the active components in the catalyst.

  13. Anion-Exchange Properties of Trifluoroacetate and Triflate Salts of N-Alkylammonium Resorcinarenes.

    Science.gov (United States)

    Pan, Fangfang; Beyeh, Ngong Kodiah; Bertella, Stefania; Rissanen, Kari

    2016-03-01

    The synthesis of N-benzyl- and N-cyclohexylammonium resorcinarene trifluoroacetate (TFA) and triflate (OTf) salt receptors was investigated. Solid-state analysis by single-crystal X-ray diffraction revealed that the N-alkylammonium resorcinarene salts (NARSs) with different upper substituents had different cavity sizes and different affinities for anions. Anion-exchange experiments by mixing equimolar amounts of N-benzylammonium resorcinarene trifluoroacetate and N-cyclohexylammonium resorcinarene triflate, as well as N-benzylammonium resorcinarene triflate and N-cyclohexylammonium resorcinarene trifluoroacetate showed that the NARS with flexible benzyl groups preferred the larger OTf anion, whereas the rigid cyclohexyl groups preferred the smaller TFA anions. The anion-exchange processes were confirmed in the solid state by single-crystal and powder X-ray diffraction experiments and in the gas phase by electrospray ionization mass spectrometry. PMID:26749383

  14. Controlled Release Kinetics in Hydroxy Double Salts: Effect of Host Anion Structure

    Directory of Open Access Journals (Sweden)

    Stephen Majoni

    2014-01-01

    Full Text Available Nanodimensional layered metal hydroxides such as layered double hydroxides (LDHs and hydroxy double salts (HDSs can undergo anion exchange reactions releasing intercalated anions. Because of this, these metal hydroxides have found applications in controlled release delivery of bioactive species such as drugs and pesticides. In this work, isomers of hydroxycinnamate were used as model compounds to systematically explore the effects of anion structure on the rate and extent of anion release in HDSs. Following intercalation and subsequent release of the isomers, it has been demonstrated that the nature and position of substituent groups on intercalated anions have profound effects on the rate and extent of release. The extent of release was correlated with the magnitude of dipole moments while the rate of reaction showed strong dependence on the extent of hydrogen bonding within the layers. The orthoisomer showed a more sustained and complete release as compared to the other isomers.

  15. A procedure for reducing the concentration of hydrogen ions in acid anionic eluate and equipment therefore

    International Nuclear Information System (INIS)

    The method is described of reducing the concentration of hydrogen ions in acid anionic eluate produced in the separation of uranium or other metals, in which anion exchanger elution, precipitation, filtration and precipitate and anion exchanger washing are used. The technological line for such elution comprises at least one ion exchange column and at least one container. They together form the first and the second stages of preparation of the acid anion elution solution, the sorption-elution separation of hydrogen ions on an cation exchanger being inserted between them. The preparation of the solution is divide into two stages. In the first stage, the acid and part of the solution for the preparation of the acid anion elution solution are supplied. The resulting enriched acid elution solution is fe onto the cation exchanger where the hydrogen ion concentration i reduced. It is then carried into the second stage where it is mixed with the remaining part of the solution. (B.S.)

  16. Action spectroscopy of gas-phase carboxylate anions by multiple photon IR electron detachment/attachment

    CERN Document Server

    Steill, Jeffrey D

    2008-01-01

    We report on a form of gas-phase anion action spectroscopy based on infrared multiple photon electron detachment and subsequent capture of the free electrons by a neutral electron scavenger in a Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer. This method allows one to obtain background-free spectra of strongly bound anions, for which no dissociation channels are observed. The first gas-phase spectra of the acetate and propionate anions are presented using SF6 as electron scavenger and a free electron laser as source of intense and tunable infrared radiation. To validate the method, we compare infrared spectra obtained through multiple photon electron detachment/attachment and multiple photon dissociation for the benzoate anion. In addition, different electron acceptors are used, comparing both associative and dissociative electron capture. The relative energies of dissociation (by CO2 loss) and electron detachment are investigated for all three anions by DFT and CCSD(T) methods. DFT calcu...

  17. Two Multi-armed Neutral Receptors for α, ω-Dicarboxylate Anions

    Institute of Scientific and Technical Information of China (English)

    WU, Jin-Long; HE, Yong-Bing; WEI, Lan-Hua; LIU, Shun-Ying; XU, Kuo-Xi; MENG, Ling-Zhi

    2006-01-01

    Two new multi-armed neutral receptors 1 and 2 containing thiourea and amide groups were synthesized by simple steps in good yields. Receptors 1 and 2 have a better selectivity and higher association constants for malonate anion than other anions examined by the present work. In particular, distinct color changes were observed upon addition of dicarboxylate anions to the solution of 1 in DMSO. The UV-Vis and fluorescence spectra data indicate that a 1: 2 stoichiometry complex was formed between compound 1 or 2 and dicarboxylate anions of shorter carbon chain, and a 1: 1 stoichiometry complex was formed between compound 1 or 2 and dicarboxylate anions of longer carbon chain through hydrogen bonding interactions.

  18. The Effects of Molecular Anions on the Chemistry of Dark Clouds

    CERN Document Server

    Walsh, Catherine; Herbst, Eric; Millar, T J

    2009-01-01

    We have investigated the role of molecular anion chemistry in pseudo-time dependent chemical models of dark clouds. With oxygen-rich elemental abundances, the addition of anions results in a slight improvement in the overall agreement between model results and observations of molecular abundances in TMC-1 (CP). More importantly, with the inclusion of anions, we see an enhanced production efficiency of unsaturated carbon-chain neutral molecules, especially in the longer members of the families CnH, CnH2, and HCnN. The use of carbon-rich elemental abundances in models of TMC-1 (CP) with anion chemistry worsens the agreement with observations obtained in the absence of anions.

  19. Aprotic Heterocyclic Anion Triazolide Ionic Liquids - A New Class of Ionic Liquid Anion Accessed by the Huisgen Cycloaddition Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Robert L; Damodaran, Krishnan; Luebke, David; Nulwala, Hunaid

    2013-06-01

    The triazole core is a highly versatile heterocyclic ring which can be accessed easily with the Cu(I)-catalyzed Huisgen cycloaddition reaction. Herein we present the preparation of ionic liquids that incorporate a 1,2,3-triazolide anion. These ionic liquids were prepared by a facile procedure utilizing a base-labile pivaloylmethyl group at the 1-position, which can act as precursors to 1H- 4-substituted 1,2,3-triazole. These triazoles were then subsequently converted into ionic liquids after deprotonation using an appropriate ionic liquid cation hydroxide. The densities and thermal decompositions of these ionic liquids were measured. These novel ionic liquids have potential applications in gas separations and in metal-free catalysis.

  20. Simultaneous determination of NH4+, NO2- and NO3- by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent%Simultaneous determination of NH4+,NO2- and NO3- by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent

    Institute of Scientific and Technical Information of China (English)

    Masanobu MORI; Takahiro HIRONAGA; Hideyuki ITABASHI; Nobutake NAKATANI; Daisuke KOZAKI; Kazuhiko TANAKA

    2012-01-01

    Ion-exclusion/anion-exchange chromatography (IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH--form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion ( NH4+ ),nitrite ion (NO2-),and nitrate ion (NO3-) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity (TSKgel Super IC-Anion) showed well-resolved separation of cations and anions,In the optimization of the basic eluent,lithium hydroxide (LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH4+,NO2-,and NO3- ranged 1.28% - 3.57% and 0.54% - 1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH4+,1.87 μmol/L for NO2- and 2.83 μmol/L for NO3-.

  1. Conversion kinetics for smelt anions: cyanate and sulfide

    Energy Technology Data Exchange (ETDEWEB)

    DeMartini, N.

    2004-07-01

    Cyanate and sulfide are two anions found in the molten salts (smelt) from the kraft recovery boiler of the chemical recovery cycle. Their concentrations in smelt are significantly different, as are their origins. The concentration of cyanate in smelt ranges between 0.4 and 2.1 g OCN{sup -}/kg smelt while the concentration of sulfide ranges between 78 and 115 g S{sup 2-}/kg smelt. Cyanate is a by-product of black liquor combustion. It is formed from organic nitrogen compounds in black liquor during the char burning stage. The charge of the cyanate anion is balanced by the alkali metals found in smelt, namely sodium and potassium. It has been found that the nitrogen in cyanate represents about 30% of the nitrogen entering the recovery boiler with the black liquor. This flow is similar in magnitude to the flows of black liquor nitrogen exiting the recovery boiler as the gaseous compounds NO and N{sub 2}. The method for cyanate analysis used in this work is presented in the Methods chapter of this thesis and Paper I. The results from nitrogen balances at three European kraft pulp mills are discussed in this thesis and Papers II and III, with a focus on the fate of cyanate in the recovery boiler and recausticizing process. Cyanate exits the recovery boiler with the smelt and reacts to form ammonia in the recausticizing solutions of the chemical recovery cycle. Papers IV and V of this thesis focus on the rate of ammonia formation from cyanate in model solutions and in kraft green liquors. The experiments were carried out at temperatures of 80 to 95 deg C, which are temperatures similar to those found in the recausticizing process of a kraft pulp mill. The kinetic studies help clarify the catalytic effect of bicarbonate. A rate equation applicable for use in describing ammonia formation from cyanate in highly alkaline solutions such as pulp mill recovery streams is presented. The sulfide anion, on the other hand, is a desired product of black liquor combustion as the

  2. Electroactive Materials for Anion Separation -- Technetium from Nitrate

    International Nuclear Information System (INIS)

    The general aim of this project is to design and prepare new electroactive ion-exchange (EaIX) materials that can be used to remove the radioactive components from high-level radioactive waste (HLW) at U.S. Department of Energy (DOE) sites nationwide. The specific objective is to develop and investigate redox-active polymers, such as polyvinylferrocene (PVF), that can be used to remove pertechnetate (TcO4-) ion from HLW. Electroactive materials are an important class of materials for this application because they can minimize or eliminate secondary waste streams associated with HLW processing, thereby reducing the costs of environmental cleanup. The technologies currently available for treatment and disposal of approximately 90 million gallons of HLW at the DOE Savannah River Site, Idaho National Engineering and Environmental Laboratory, and Hanford Site are neither cost-effective nor practical. Processes to separate the HLW constituents from the low-level waste (LLW) fraction are required to reduce the volume of waste that must be treated and disposed of and to reduce the cost of treatment and disposal. Use of EaIX materials, conjoined with the use of porous membranes that also are under development, can significantly reduce or eliminate secondary wastes associated with more traditional ion-exchange or solvent extraction technologies and, thus, can help improve the effectiveness and reduce the cost of DOE's waste treatment and disposal efforts. Beyond its importance as a cost issue, separation of TcO4- from HLW also addresses a critical environmental issue. The most common isotope of technetium (99Tc) has an extremely long half-life of 210,000 years. Rapid development of advanced methods to remove and separate this long-lived radioactive isotope is important because most of the technetium in the DOE HLW probably is in the form of TcO4-, which is highly mobile in soils and groundwater. This project is focused on anion separation and, in particular, the selective

  3. Potential applications of solar reactions photocatalysed by the decatungstate anion

    Science.gov (United States)

    Texier, I.; Giannotti, C.; Malato, S.; Richter, C.; Ouazzani, J.; Delaire, J.

    1999-03-01

    Two potential applications of photocatalysed reactions in the presence of the decatungstate anion W{10}O{32}4- under solar ligth irradiation were explored. Firstly, we investigated the possibility offered by alkane fonctionalisation. By irradiation with [ (tBut)4N] 4W{10}O{32}, cyclohexane was converted into cyclohexanone and cyclohexane hydroperoxide, which give cyclohexanol after reduction. A small amount of polyoxygenated products is also formed. Secondly, we studied the potential of Na4W{10}O{32} to act as a photocatalyst for water depollution processes. Several phenols and pesticides, especially atrazine, were used as substrates and the results were compared to those obtained in the presence of TiO2. Since neither TiO2 nor Na4W{10}O{32} lead to the total mineralisation of atrazine, we made an attempt for integrating photo- and biodegradation processes in order to achieve the total mineralisation of the pollutant. Deux applications potentielles des réactions photocatalysées par l'anion décatungstate W{10}O{32}4- sous irradiation solaire ont été explorées. Premièrement, nous avons examiné les possibilités offertes pour la functionalization des alcanes. Par irradiation en présence de [ (tBut)4N] 4W{10}O{32}, le cyclohexane est converti directement en cyclohexanone et en hydroperoxyde, qui produit après réduction du cyclohexanol. Une petite quantité de produits polyoxygénés est également formée. Deuxièmement, nous avons étudié les potentialités d'action de Na4W{10}O{32} en tant que photocatalyseur pour la dépollution des eaux. Différents phénols et pesticides, dont l'atrazine, ont été utilisés comme substrats et les résultats comparés à ceux obtenus en présence de TiO2. Ni TiO2, ni Na4W{10}O{32} ne conduisant à la minéralisation de l'atrazine, nous avons essayé d'intégrer photo- et biodégradation dans le but d'obtenir la minéralisation totale du polluant.

  4. Novel heterocyclic thiosemicarbazones derivatives as colorimetric and “turn on” fluorescent sensors for fluoride anion sensing employing hydrogen bonding

    Science.gov (United States)

    Ashok Kumar, S. L.; Saravana Kumar, M.; Sreeja, P. B.; Sreekanth, A.

    2013-09-01

    Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques.

  5. Separation and determination of alditols and sugars by high-pH anion-exchange chromatography with pulsed amperometric detection

    DEFF Research Database (Denmark)

    Andersen, Rikke; Sørensen, A.

    2000-01-01

    Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic...

  6. Generation of naphthoquinone radical anions by electrospray ionization: solution, gas-phase, and computational chemistry studies.

    Science.gov (United States)

    Vessecchi, Ricardo; Naal, Zeki; Lopes, José N C; Galembeck, Sérgio E; Lopes, Norberto P

    2011-06-01

    Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses. PMID:21561138

  7. Analysis of anionic post-blast residues of low explosives from soil samples of forensic interest

    International Nuclear Information System (INIS)

    The growing threats and terrorist activities in recent years have urged the need for rapid and accurate forensic investigation on post-blast samples. The analysis of explosives and their degradation products in soils are important to enable forensic scientist to identify the explosives used in the bombing and establish possible links to their likely origin. Anions of interest for post-blast identification of low explosives were detected and identified using ion chromatography (IC). IC separations of five anions (Cl-, NO2-, NO3-, SO42-, SCN-) employed a Metrosep Anion Dual 2 column with carbonate eluent. The anions were separated within 17 minutes. Sampling of post blast residues was carried out in Rompin, Pahang. The post-blast explosive residues were extracted from soil samples collected at the seat of three simulated explosion points. The homemade explosives comprised of black powder of various amounts (100 g, 150 g and 200 g) packed in small plastic sauce bottles. In black powder standard, three anions (Cl-, NO3-, SO42-) were identified. However, low amounts of nitrite (NO2-) were found present in post-blast soil samples. The amounts of anions were generally found to be decreased with decreasing amount of black powder explosive used. The anions analysis was indicative that nitrates were being used as one of the black powder explosive ingredients. (author)

  8. Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface.

    Science.gov (United States)

    Wang, Siming; Li, Zenghe; Lu, Chao

    2015-11-15

    Polyethyleneimine (PEI) is a positively charged polymer with hydrogen-bonding sites and hydrophobic chains. Therefore, it has been clearly established as an efficient adsorbent by means of these native properties in the literatures. However, there is apparently no good reason to disregard the use of PEI as a desired desorbent. Herein, using methyl orange as a model anionic dye, we investigated the desorption performances of PEI toward anionic dyes adsorbed on the surface of CO3-layered double hydroxides (LDHs) in a wide range of pH values. The experiment results showed that the positively charged PEI had very strong desorption capacity for anionic dyes at low pH values (9.5), PEI existed as neutral molecule, it could desorb methyl orange via hydrogen bonding between the amino groups of it and sulfonate group of methyl orange; simultaneously, the anion-exchange process occurred between abundant hydroxyl anions and anionic methyl orange. The adsorption capacity of the used LDH adsorbent was about 80% after five cycles of adsorption-desorption-regeneration, which was much higher than that conducted by 0.1M NaOH solution. These findings suggested that PEI could be regarded as a promising desorbent for enriching anionic dyes in wastewater and regenerating LDHs through surface adsorption-desorption cycles. PMID:26255712

  9. Low-lying electronic structure of EuH, EuOH, and EuO neutrals and anions determined by anion photoelectron spectroscopy and DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kafader, Jared O.; Ray, Manisha; Jarrold, Caroline Chick, E-mail: cjarrold@indiana.edu [Department of Chemistry, Indiana University, Bloomington, Indiana 47405 (United States)

    2015-07-21

    The anion photoelectron (PE) spectra of EuH{sup −} and the PE spectrum of overlapping EuOH{sup −} and EuO{sup −} anions are presented and analyzed with supporting results from density functional theory calculations on the various anions and neutrals. Results point to ionically bound, high-spin species. EuH and EuOH anions and neutrals exhibit analogous electronic structures: Transitions from {sup 8}Σ{sup −} anion ground states arising from the 4f{sup 7}σ{sub 6s}{sup 2} superconfiguration to the close-lying neutral {sup 9}Σ{sup −} and {sup 7}Σ{sup −} states arising from the 4f{sup 7}σ{sub 6s} superconfiguration are observed spaced by an energy interval similar to the free Eu{sup +} [4f{sup 7}6s] {sup 9}S - {sup 7}S splitting. The electron affinities (EAs) of EuH and EuOH are determined to be 0.771 ± 0.009 eV and 0.700 ± 0.011 eV, respectively. Analysis of spectroscopic features attributed to EuO{sup −} photodetachment is complicated by the likely presence of two energetically competitive electronic states of EuO{sup −} populating the ion beam. However, based on the calculated relative energies of the close-lying anion states arising from the 4f{sup 7}σ{sub 6s} and 4f{sup 6}σ{sub 6s}{sup 2} configurations and the relative energies of the one-electron accessible 4f{sup 7} and 4f{sup 6}σ{sub 6s} neutral states based on ligand-field theory [M. Dulick, E. Murad, and R. F. Barrow, J. Chem. Phys. 85, 385 (1986)], the remaining features are consistent with the 4f{sup 6}σ{sub 6s}{sup 2}  {sup 7}Σ{sup −} and 4f{sup 7}σ{sub 6s}{sup 7}Σ{sup −} anion states lying very close in energy (the former was calculated to be 0.15 eV lower in energy than the latter), though the true anion ground state and neutral EA could not be established unambiguously. Calculations on the various EuO anion and neutral states suggest 4f-orbital overlap with 2p orbitals in species with 4f{sup 6} occupancy.

  10. Theoretical investigations on the layer-anion interaction in Mg-Al layered double hydroxides: Influence of the anion nature and layer composition

    Science.gov (United States)

    Cuautli, Cristina; Ireta, Joel

    2015-03-01

    The influence of the anion nature and layer composition on the anion-layer interaction in Mg-Al layered double hydroxides (LDHs) is investigated using density functional theory. Changes in the strength of the anion-layer interaction are assessed calculating the potential energy surface (PES) associated to the interlayer anion (OH-/Cl-) in Mg-Al-OH and Mg-Al-Cl LDHs. The layer composition is varied changing the divalent to trivalent cation proportion (R). Mg-Al-OH is thus investigated with R = 2, 3, 3.5 and Mg-Al-Cl with R = 3. It is found that the PES for OH- in Mg-Al-OH/R = 3 presents wider energy basins and lower energy barriers than any other of the investigated compositions. It is shown that the latter is connected to the number of hydrogen bonds formed by the anions. These results have interesting implications for understanding the enhancement of the physicochemical properties of LDHs upon changing composition.

  11. Hydroxide Solvation and Transport in Anion Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chen [Univ. of Chicago, IL (United States); Wuhan Univ. (China); Tse, Ying-Lung Steve [Univ. of Chicago, IL (United States); Lindberg, Gerrick E. [Northern Arizona Univ., Flagstaff, AZ (United States); Knight, Chris [Argonne National Lab. (ANL), Argonne, IL (United States); Voth, Gregory A. [Univ. of Chicago, IL (United States)

    2016-01-27

    Understanding hydroxide solvation and transport in anion exchange membranes (AEMs) can provide important insight into the design principles of these new membranes. To accurately model hydroxide solvation and transport, we developed a new multiscale reactive molecular dynamics model for hydroxide in aqueous solution, which was then subsequently modified for an AEM material. With this model, we investigated the hydroxide solvation structure and transport mechanism in the membrane. We found that a relatively even separation of the rigid side chains produces a continuous overlapping region for hydroxide transport that is made up of the first hydration shell of the tethered cationic groups. Our results show that hydroxide has a significant preference for this overlapping region, transporting through it and between the AEM side chains with substantial contributions from both vehicular (standard diffusion) and Grotthuss (proton hopping) mechanisms. Comparison of the AEM with common proton exchange membranes (PEMs) showed that the excess charge is less delocalized in the AEM than the PEMs, which is correlated with a higher free energy barrier for proton transfer reactions. The vehicular mechanism also contributes considerably more than the Grotthuss mechanism for hydroxide transport in the AEM, while our previous studies of PEM systems showed a larger contribution from the Grotthuss mechanism than the vehicular mechanism for proton transport. The activation energy barrier for hydroxide diffusion in the AEM is greater than that for proton diffusion in PEMs, implying a more significant enhancement of ion transport in the AEM at elevated temperatures.

  12. Anion-exchange separations of metal ions in thiocyanate media.

    Science.gov (United States)

    Fritz, J S; Kaminski, E E

    1971-05-01

    The analytical potential of a weak-base macroreticular anion-exchange resin for the quantitative separation of metal ions in thiocyanate media is investigated and demonstrated. Distribution data are given for the sorption of some 25 metal ions from aqueous mixtures of potassium thiocyanate (1.0M or less) and 0.5M hydrochloric acid. The magnitude of the distribution data suggests many possible separations, some of which were quantitatively performed by procedures which are fast, simple and require only mild conditions. Representative separations are removal of traces of iron(III) and copper(II) from water samples prior to the determination of water hardness (calcium and magnesium), separation of nickel(II) from vanadium(IV) and the separation of thorium(IV) from titanium(IV). Some multicomponent separations are the separation of rare earths(III) and thorium(IV) from scandium(III) and the separation of rare earths(III) from iron(III) and uranium(VI). PMID:18960914

  13. Computer simulation of methanol exchange dynamics around cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.

    2016-03-03

    In this paper, we present the first computer simulation of methanol exchange dynamics between the first and second solvation shells around different cations and anions. After water, methanol is the most frequently used solvent for ions. Methanol has different structural and dynamical properties than water, so its ion solvation process is different. To this end, we performed molecular dynamics simulations using polarizable potential models to describe methanol-methanol and ion-methanol interactions. In particular, we computed methanol exchange rates by employing the transition state theory, the Impey-Madden-McDonald method, the reactive flux approach, and the Grote-Hynes theory. We observed that methanol exchange occurs at a nanosecond time scale for Na+ and at a picosecond time scale for other ions. We also observed a trend in which, for like charges, the exchange rate is slower for smaller ions because they are more strongly bound to methanol. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

  14. Inactivation of Bacillus Subtilis by Atomic Oxygen Radical Anion

    Institute of Scientific and Technical Information of China (English)

    LI Longchun; WANG Lian; YU Zhou; LV Xuanzhong; LI Quanxin

    2007-01-01

    UAtomic oxygen radical anion (O- ) is one of the most active oxygen species, and has extremely high oxidation ability toward small-molecules of hydrocarbons. However, to our knowledge, little is known about the effects of O- on cells of micro-organisms. This work showed that O- could quickly react with the Bacillus subtilis cells and seriously damage the cell walls a s well as their other contents, leading to a fast and irreversible inactivation. SEM micrographs revealed that the cell structures were dramatically destroyed by their exposure to O-. The inactivation efficiencies of B. subtilis depend on the O-- intensity, the initial population of cells and the treatment temperature, but not on the pH in the range of our investigation. For a cell concentration of 106 cfu/ml, the number of survived cells dropped from 106 cfu/ml to 103 cfu/ml after about five-minute irradiation by an O- flux in an intensity of 233 nA/cm2 under a dry argon environment (30 ℃, 1 atm, exposed size: 1.8 cm2). The inactivation mechanism of micro-organisms induced by O- is also discussed.

  15. Conductance hysteresis in the voltage-dependent anion channel.

    Science.gov (United States)

    Rappaport, Shay M; Teijido, Oscar; Hoogerheide, David P; Rostovtseva, Tatiana K; Berezhkovskii, Alexander M; Bezrukov, Sergey M

    2015-09-01

    Hysteresis in the conductance of voltage-sensitive ion channels is observed when the transmembrane voltage is periodically varied with time. Although this phenomenon has been used in studies of gating of the voltage-dependent anion channel, VDAC, from the outer mitochondrial membrane for nearly four decades, full hysteresis curves have never been reported, because the focus was solely on the channel opening branches of the hysteresis loops. We studied the hysteretic response of a multichannel VDAC system to a triangular voltage ramp the frequency of which was varied over three orders of magnitude, from 0.5 mHz to 0.2 Hz. We found that in this wide frequency range the area encircled by the hysteresis curves changes by less than a factor of three, suggesting broad distribution of the characteristic times and strongly non-equilibrium behavior. At the same time, quasi-equilibrium two-state behavior is observed for hysteresis branches corresponding to VDAC opening. This enables calculation of the usual equilibrium gating parameters, gating charge and voltage of equipartitioning, which were found to be almost insensitive to the ramp frequency. To rationalize this peculiarity, we hypothesize that during voltage-induced closure and opening the system explores different regions of the complex free energy landscape, and, in the opening branch, follows quasi-equilibrium paths.

  16. Light-responsive viscoelastic fluids based on anionic wormlike micelles.

    Science.gov (United States)

    Lu, Yechang; Zhou, Tengfei; Fan, Qing; Dong, Jinfeng; Li, Xuefeng

    2013-12-15

    A new class of light-responsive viscoelastic fluids based on anionic wormlike micelles is reported. The key components are sodium oleate (NaOA) and a cationic azobenzene dye, 1-[2-(4-phenylazo-phenoxy)-ethyl]-3-methylimidazolium bromide (C0AZOC2IMB). These binary systems are gel-like fluids at certain concentration ratios of [C0AZOC2IMB]/[NaOA], e.g. 35/100, owing to the formation of long, entangled wormlike micelles. The viscosity of these fluids can be controlled reversibly by light due to photo isomerization between trans-C0AZOC2IMB and cis-C0AZOC2IMB. For example, the zero-shear viscosity (η0) of an originally gel-like sample is high up to ~1300 Pa s when C0AZOC2IMB is in its trans from, whereas the mixture becomes a Newtonian fluid with η0 about 0.01 Pa s after UV light irradiation. For the post-irradiated cis-C0AZOC2IMB, short cylindrical micelles form, hence accounting for the lower viscosity. Evidence for the structural transition is provided by UV-vis spectra, rheology, (1)H NMR and cryo-transmission electronic microscopy measurements. PMID:24144381

  17. Gamma radiation effect on gas production in anion exchange resins

    International Nuclear Information System (INIS)

    Radiation-induced decomposition of Amberlite IRA400 anion exchange resin in hydroxide form by gamma radiolysis has been studied at various doses in different atmospheres (anaerobic, anaerobic with liquid water, and aerobic). The effect of these parameters on the degradation of ion exchange resins is rarely investigated in the literature. We focused on the radiolysis gases produced by resin degradation. When the resin was irradiated under anaerobic conditions with liquid water, the liquid phase over the resin was also analyzed to identify any possible water-soluble products released by degradation of the resin. The main products released are trimethylamine (TMA), molecular hydrogen (H2g) and carbon dioxide (CO2g). TMA and H2g are produced in all the irradiation atmospheres. However, TMA was in gaseous form under anaerobic and aerobic conditions and in aqueous form in presence of liquid water. In the latter conditions, TMAaq was associated with aqueous dimethylamine (DMAaq), monomethylamine (MMAaq) and ammonia (NH4+aq). CO2g is formed in the presence of oxygen due to oxidation of organic compounds present in the system, in particular the degradation products such as TMAg

  18. Studies on Anionic Surfactant Structure in the Aggregation with (Hydroxypropylcellulose

    Directory of Open Access Journals (Sweden)

    Ricardo M. de Martins

    2002-01-01

    Full Text Available Fluorescence probing, viscosity and light scattering measurements have been combined to study the aggregation of different anionic surfactants mainly in dilute solutions (0.5% w/v of (hydroxypropylcellulose (HPC MW 173,000, in moderate ionic strength (NaCl 0.1 mol.L-1. The set of surfactants includes natural cholesterol derivatives, sodium cholate (CS and sodium deoxycholate (DC, and the alkylsulphate, sodium dodecylsulphate (SDS. At 298 K the critical surfactant concentration related to aggregate/HPC formation (C1 decreases for SDS and DC whereas it increases slightly for CS. At 312 K the C1 values for CS and DC are slightly shifted toward higher values whereas it is not changed for SDS. All surfactant/HPC systems increase C1 values as the HPC concentration increases to 1.2%. Above C1 the viscosity increases for all surfactant/HPC systems but it is sharper in the increasing order CS, DC and SDS. The hydrodynamic behavior indicates that CS induces higher diffusion to HPC than SDS and DC. The aggregation in the surfactant/HPC systems is analyzed through the feature of surfactant/aggregate structure (size, charge density, etc.

  19. Positive Anharmonicities: The Oxonide Anion as an Example

    Science.gov (United States)

    Lee, Timothy J.; Arnold, James O. (Technical Monitor)

    1997-01-01

    An accurate ab initio quartic force field for the ozonide anion has been determined at the singles and doubles coupled-cluster level of theory that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T), using the augmented valence triple-zeta correlation consistent one-particle basis set. Convergence of the harmonic frequencies with respect to the one-particle basis set has been demonstrated by computing quadratic force fields at the CCSD(T) level using augmented valence double-zeta and quadruple-zeta basis sets. Fundamental vibrational frequencies have been determined via second-order ro-vibrational perturbation theory and also using exact variational methods. Agreement is very good, and they both show that the antisymmetric O-O stretch, v 3, possesses a positive anharmonic correction (that is, the fundamental frequency is predicted to be higher in energy than the harmonic frequency). Comparison of the O_3 and O3 quartic force fields shows that the positive anharmonic correction is the result of a particularly large F3333 symmetry internal coordinate force constant. The reasonableness of this force constant has been tested by computing both F33 and F3333 at the CCSD, CCSD(T), and CASPT2 levels of theory. A discussion of known positive anharmonicities for stretching modes is presented.

  20. Photoelectron imaging spectroscopy of niobium mononitride anion NbN(.).

    Science.gov (United States)

    Berkdemir, Cuneyt; Gunaratne, K Don Dasitha; Cheng, Shi-Bo; Castleman, A W

    2016-07-21

    In this gas-phase photoelectron spectroscopy study, we present the electron binding energy spectrum and photoelectron angular distributions of NbN(-) by the velocity-map imaging technique. The electron binding energy of NbN(-) is measured to be 1.42 ± 0.02 eV from the X band maximum which defines the 0-0 transition between ground states of anion and neutral. Theoretical binding energies which are the vertical and adiabatic detachment energies are computed by density functional theory to compare them with experiment. The ground state of NbN(-) is assigned to the (2)Δ3/2 state and then the electronic transitions originating from this state into X(3)ΔΩ (Ω = 1-3), a(1)Δ2, A(3)Σ1 (-), and b(1)Σ0 (+) states of NbN are reported to interpret the spectral features. As a prospective study for catalytic materials, spectral features of NbN(-) are compared with those of isovalent ZrO(-) and Pd(-). PMID:27448881

  1. Communication: Solute Anisotropy Effects in Hydrated Anion and Neutral Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Hui; Hou, Gao-Lei; Kathmann, Shawn M.; Valiev, Marat; Wang, Xue B.

    2013-01-21

    Specific ion effects in solvation processes are often rationalized in terms of spherically symmetric models involving an ion’s size, charge, and polarizability. The effects of permanent charge anisotropy, related to the polyatomic nature of complex solutes, are expected to play a role in solvation but the extent of their importance remains unexplored. In this work we provide compelling experimental and theoretical evidence that the anisotropic nature of complex polyoxyanion solutes can have a critical influence on the solvation process. Combined photoelectron spectroscopy and theoretical modeling results show that the electron binding energy (EBE) of IO3-(H2O)n (n = 0 - 12) clusters is characterized by an anomalous drop at n = 10. Such behavior is unprecedented for rigid solute molecules, and is related to the anisotropy of the neutral iodate radical that displays a strong selectivity to solvent configurations generated by the charged anion complex. These results highlight the significance of solute anisotropy and its potential impact on ion specificity and selectivity in aqueous environments.

  2. Highly conductive side chain block copolymer anion exchange membranes.

    Science.gov (United States)

    Wang, Lizhu; Hickner, Michael A

    2016-06-28

    Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days. PMID:27216558

  3. Adsorption and intercalation of anionic surfactants onto layered double hydroxides—XRD study

    Indian Academy of Sciences (India)

    R Anbarasan; W D Lee; S S Im

    2005-04-01

    Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate, carboxyl and phosphonate group containing surfactant led to an intercalation process. This can be evidenced from the change in basal spacing of LDH. The presence of anionic surfactants in the LDH was supported by FTIR spectroscopy. The FTIR spectrum indicated that complete removal of carbonate anion from the inter layer space of LDH is very difficult. The phosphonate intercalated HT showed less thermal stability than pristine LDH.

  4. Novel anthracene-based fluorescent sensor for selective recognition of acetate anions in protic media

    Science.gov (United States)

    Xu, Kuoxi; Kong, Huajie; Li, Qian; Song, Pan; Dai, Yanpeng; Yang, Li

    2015-02-01

    Novel 9-substituted anthracene derivatives were synthesized and characterized by IR, HRMS, 1H and 13C NMR. The fluorescence titration experiments were explored to study the interaction between the compounds and some anions, such as H2PO4-, P2O74-, F-, Cl-, Br-, I-, AcO- in H2O (0.01 M HEPES, pH = 7.4) under imitated physiological conditions. One of these compounds, bearing a phenylalaninol unit, showed specific fluorescence enhancement with acetate anion. The sensor L1 was found to present good selective fluorescence sensing ability to acetate anion through photoinduced electron-transfer mechanism in protic media.

  5. Cation-π versus anion-π interactions: A theoretical NMR study

    Science.gov (United States)

    Ebrahimi, Ali; Khorassani, Mostafa Habibi; Masoodi, Hamid Reza

    2011-03-01

    The influences of cation-π and anion-π interactions on NMR data have been investigated in complexes of cations and anions with 1,3,5-trifluorobenzene (TFB). Cation-π interaction increases 1JC-F, 1JC-H and the chemical shifts of hydrogen and fluorine while it decreases 1JC-C. The changes are in reverse direction in the presence of anion-π interaction. The role of geometry and electronic effects on the NMR data was considered. The distance dependence of NMR parameters has been studied in these complexes. The NMR data have been investigated in isoelectronic complexes.

  6. Calcium ion activity in physiological salt solutions: influence of anions substituted for chloride

    DEFF Research Database (Denmark)

    Christoffersen, Gert Rene Juul; Skibsted, Leif H

    1975-01-01

    1. Substitution by different anions for chloride in physiological salt solutions leads to binding between Ca2+ and the anion. Experiments designed to test effects of Cl- therefore often show mixed effects of changes in Cl- and Ca2+ activity.   2. This mixed effect is demonstrated in neurons...... of the snail, Helix pomatia: current-voltage characteristics and membrane potential are described during reduction of extracellular Cl- using different anions as substitutes. Methylsulphate is concluded to be the best substitute in this preparation. 3. The association constants for the binding of Ca2...

  7. Adsorption of anionic surfactant at the electrode–NaClO4 solution interface

    OpenAIRE

    Gugała-Fekner, Dorota; Nieszporek, Jolanta; Sieńko, Dorota

    2015-01-01

    Abstract Adsorption of 1-decanesulfonic acid at the electrode–NaClO4 solution interface was determined by double-layer differential capacity measurements. At potentials less than −1,200 mV, the adsorption of the anionic surfactant on the electrode does not occur. Low concentrations of the anionic surfactant (below cmc) causes slight changes in the zero charge potential, E z, and the surface tension at this potential, γ z. The adsorption of the anionic surfactant was analyzed using the constan...

  8. Electrochemical behavior of LiFePO4 cathode materials in the presence of anion adsorbents

    International Nuclear Information System (INIS)

    The poor rate capability is a major problem of olivine-structured lithium iron phosphate (LFP) cathode material in lithium-ion batteries due to its low electric conductivity and sluggish lithium diffusion. Other than the custom strategies to solve this problem like carbon coating and nano-size treatment, we simply mixed LFP with some anion adsorbents, which can store anions from the electrolytes swiftly. The effect of anion adsorbents on the performance of LFP composite electrode has been investigated by cyclic voltammetric tests and the corresponding apparent lithium diffusion coefficients have been measured

  9. Anionic and zwitterionic carboranyl N-heterocyclic carbene Au(i) complexes.

    Science.gov (United States)

    Fisher, Steven P; El-Hellani, Ahmad; Tham, Fook S; Lavallo, Vincent

    2016-06-14

    The syntheses of the first carboranyl N-heterocyclic carbene complexes with transition metals are reported. Both unsymmetrical mono-anionic and symmetrical dianionic NHCs readily react with ClAuSMe2 to afford unusual zwitterionic and anionic Au(i) dimethyl sulfide adducts. The compounds are characterized by NMR, mass spectrometry, and single crystal X-ray diffraction studies. Percent buried volume (%Vbur) calculations indicate that replacement of an adamantyl group by a hydride substituted icosahedral carborane anion results in a 3.7% increase in %Vbur. PMID:26922968

  10. The Al(I) molecule, Ph2COAl and its anion

    Science.gov (United States)

    Zhang, Xinxing; Eichhorn, Bryan; Schnöckel, Hansgeorg; Bowen, Kit

    2016-08-01

    We have formed the Al(I)-containing molecule, benzophenone-aluminum, i.e., Ph2COAl, and studied it by conducting density functional theory calculations on both its neutral and anionic forms and by measuring the photoelectron spectrum of its anion. Our calculations identified two nearly iso-energetic anion isomers, (Ph2COAl)-, the vertical detachment energies (VDE) of which are in excellent agreement with our photoelectron spectrum. Natural population analysis (NPA) of Ph2COAl found the Al moiety to be positively charged by +0.81 e, indicating a strongly ionic bond between Al and Ph2CO, i.e., Ph2CO-Al+.

  11. DFT modeling of adsorption of formaldehyde and methanediol anion on the (111) face of IB metals

    Science.gov (United States)

    Starodubov, S. S.; Nechaev, I. V.; Vvedenskii, A. V.

    2016-01-01

    Gas-phase adsorption of formaldehyde and gas- and liquid-phase adsorption of the methanediol anion on the (111) face of copper, silver, and gold was modeled in terms of the density functional theory and the cluster model of the metal single-crystal surface. In the gas phase, formaldehyde was found to be physically adsorbed on the metals, while the methanediol anion was found to be chemisorbed. It exists on the surface in two different stable states. In aqueous solution, the H3CO 2 - anion can spontaneously dissociate into the formate ion and two hydrogen atoms.

  12. The application of Guided Ion Beam Tandem Mass Spectrometer; Bond dissociation energies of bare and ligated copper group cluster anions

    International Nuclear Information System (INIS)

    Threshold energies, fragmentation patterns, and integral cross sections for the reactions of collision induced dissociations of bare and ligated copper group cluster anions are determined using a Guided Ion Beam Tandem Mass Spectrometer (GIB-MS). The bond breaking patterns for the copper cluster anions show dramatic even/odd tendencies, e.g., all copper group anions generate as the predominant reaction product, Carbon monoxide is weakly bound to copper group cluster anions. Cohesive energies of the bare copper and silver cluster anions are determined and exhibit a good correspondence with estimate cohesive energies by the model of Miedema.

  13. Preparation of anionic clay-birnessite manganese oxide composites by interlayer oxidation of oxalate ions by permanganate

    Science.gov (United States)

    Arulraj, James; Rajamathi, Michael

    2013-02-01

    Oxalate intercalated anionic clay-like nickel zinc hydroxysalt was obtained starting from nickel zinc hydroxyacetate, Ni3Zn2(OH)8(OAc)2·2H2O, by anion exchange. The intercalated oxalate species was reacted with potassium permanganate in such a way that the layered manganese oxide formed was within the interlayer region of the anionic clay resulting in a layered composite in which the negative charges on the birnessite type manganese oxide layers compensate the positive charges on the anionic clay layers. Birnessite to anionic clay ratio could be varied by varying the reaction time or the amount of potassium permanganate used.

  14. Extracellular Cl(-) regulates human SO4 (2-)/anion exchanger SLC26A1 by altering pH sensitivity of anion transport.

    Science.gov (United States)

    Wu, Meng; Heneghan, John F; Vandorpe, David H; Escobar, Laura I; Wu, Bai-Lin; Alper, Seth L

    2016-08-01

    Genetic deficiency of the SLC26A1 anion exchanger in mice is known to be associated with hyposulfatemia and hyperoxaluria with nephrolithiasis, but many aspects of human SLC26A1 function remain to be explored. We report here the functional characterization of human SLC26A1, a 4,4'-diisothiocyanato-2,2'-stilbenedisulfonic acid (DIDS)-sensitive, electroneutral sodium-independent anion exchanger transporting sulfate, oxalate, bicarbonate, thiosulfate, and (with divergent properties) chloride. Human SLC26A1-mediated anion exchange differs from that of its rodent orthologs in its stimulation by alkaline pHo and inhibition by acidic pHo but not pHi and in its failure to transport glyoxylate. SLC26A1-mediated transport of sulfate and oxalate is highly dependent on allosteric activation by extracellular chloride or non-substrate anions. Extracellular chloride stimulates apparent V max of human SLC26A1-mediated sulfate uptake by conferring a 2-log decrease in sensitivity to inhibition by extracellular protons, without changing transporter affinity for extracellular sulfate. In contrast to SLC26A1-mediated sulfate transport, SLC26A1-associated chloride transport is activated by acid pHo, shows reduced sensitivity to DIDS, and exhibits cation dependence of its DIDS-insensitive component. Human SLC26A1 resembles SLC26 paralogs in its inhibition by phorbol ester activation of protein kinase C (PKC), which differs in its undiminished polypeptide abundance at or near the oocyte surface. Mutation of SLC26A1 residues corresponding to candidate anion binding site-associated residues in avian SLC26A5/prestin altered anion transport in patterns resembling those of prestin. However, rare SLC26A1 polymorphic variants from a patient with renal Fanconi Syndrome and from a patient with nephrolithiasis/calcinosis exhibited no loss-of-function phenotypes consistent with disease pathogenesis. PMID:27125215

  15. Nanostructure-controlled anion exchange membranes for fuel cell applications by high-energy heavy-ion irradiation. Preparation and characterization of anion exchange membranes

    International Nuclear Information System (INIS)

    Heavy ions at kinetic energies typically from several hundreds of MeV to a few GeV passing through a polymer substrate induce a continuous trail of excitations and ionizations called latent tracks. We used a direct ion-track grafting method for preparation of anion exchange membranes for fuel cells. The functional anion exchange groups were introduced inside the latent tracks, thereby achieving OH--conductive channels through the thickness. These straight channels increased conductivities, while the isolated cylindrical structure of tracks restricted the water uptake. (author)

  16. Anion directed supramolecular architecture of benzimidazole-based receptor

    Science.gov (United States)

    Singh, Udai P.; Maurya, Radha Raman; Kashyap, Sujata

    2015-02-01

    The reaction of N,N,N‧,N‧-tetrakis-(1H,benzimidazol-2ylmethyl)ethane-1,2-diamine (L) with different inorganic as well as organic acid afford salts viz., LH44+·4ClO4-·4H2O (1), LH44+·4Br-·4(CH3)2SO (2), 2LH33+·3SiF62-·14H2O (3), LH44+·4H2PO4-·2H3PO4 (4) and L·2CH3COOH (5) with different structures. The X-ray crystallographic studies revealed that these compounds are all ionic in nature due to proton transfer except 5 and are stabilized in the solid state by networks of hydrogen bonds between their respective components as well as solvent molecules. It also demonstrates that different types of hydrogen bond between protonated ligand and the anions are responsible for the extensive supramolecular frame work. The three dimensional packing is mainly guided by well-balanced primary N-H⋯O, O-H⋯N, O-H⋯O hydrogen bonds and secondary C-H⋯O interactions between benzimidazole and acids. Moreover, the hydrogen bonds, π⋯π and C-H⋯π stacking interactions appear to be effective in stabilizing the crystal structures. The colorimetric test showed color change upon the addition of acids in solution of the ligand. The photo-physical experiments suggest that the ligand shows fluorescence properties in the presence of acids.

  17. Solution Properties of Dissymmetric Sulfonate-type Anionic Gemini Surfactants.

    Science.gov (United States)

    Yoshimura, Tomokazu; Akiba, Kazuki

    2016-01-01

    Dissymmetric and symmetric anionic gemini surfactants, N-alkyl-N'-alkyl-N,N'dipropanesulfonylethylenediamine (CmCnSul, where m and n represent alkyl chain lengths of m-n = 4-16, 6-14, 8-12, 10-10, and 12-12), were synthesized by two- or three-step reactions. Their physicochemical properties were characterized by equilibrium surface tension measurements, steady-state fluorescence spectroscopy of pyrene, and dynamic light scattering. The critical micelle concentration (CMC) of the dissymmetric surfactants C4C16Sul, C6C14Sul, and C8C12Sul was slightly lower than that of the symmetric surfactant C10C10Sul. The occupied area per molecule (A) of C8C12Sul was smaller than that of C10C10Sul, indicating that C8C12Sul has a high surface activity. However, the increase in the degree of dissymmetry from C8C12Sul to C6C14Sul and then to C4C16Sul resulted in high surface tension and large A. Based on the surface tension, the standard free energies of micellization (∆G°mic) and adsorption (∆G°ads), the efficiency of surface adsorption (pC20), and the effectiveness of surface adsorption (CMC/C20) were obtained. These parameters suggested that C8C12Sul formed micelles more readily than the other surfactants. The properties determined from the surface tension indicated that C8C12Sul's ability is intermediate between those of C10C10Sul and C12C12Sul. The pyrene fluorescence and dynamic light scattering results revealed that the micelle size depends on the longer of the two alkyl chains in dissymmetric surfactants. PMID:26782304

  18. 3D Printing of Micropatterned Anion Exchange Membranes.

    Science.gov (United States)

    Seo, Jiho; Kushner, Douglas I; Hickner, Michael A

    2016-07-01

    Micropatterned anion exchange membranes (AEMs) have been 3D printed via a photoinitiated free radical polymerization and quaternization process. The photocurable formulation, consisting of diurethane dimethacrylate (DUDA), poly(ethylene glycol) diacrylate (PEGDA), dipentaerythritol penta-/hexa- acrylate, and 4-vinylbenzyl chloride (VBC), was directly cured into patterned films using a custom 3D photolithographic printing process similar to stereolithography. Measurements of water uptake, permselectivity, and ionic resistance were conducted on the quaternized poly(DUDA-co-PEGDA-co-VBC) sample series to determine their suitability as ion exchange membranes. The water uptake of the polymers increased as the ion exchange capacity (IEC) increased due to greater quaternized VBC content. Samples with IEC values between 0.98 to 1.63 mequiv/g were synthesized by varying the VBC content from 15 to 25 wt %. The water uptake was sensitive to the PEGDA content in the network resulting in water uptake values ranging from 85 to 410 wt % by varying the PEGDA fractions from 0 to 60 wt %. The permselectivity of the AEM samples decreased from 0.91 (168 wt %, 1.63 mequiv/g) to 0.85 (410 wt %, 1.63 mequiv/g) with increasing water uptake and to 0.88 (162 wt %, 0.98 mequiv/g) with decreasing IEC. Permselectivity results were relatively consistent with the general understanding of the correlation between permselectivity, water uptake, and ion content of the membrane. Lastly, it was revealed that the ionic resistance of patterned membranes was lower than that of flat membranes with the same material volume or equivalent thickness. A parallel resistance model was used to explain the influence of patterning on the overall measured ionic resistance. This model may provide a way to maximize ion exchange membrane performance by optimizing surface patterns without chemical modification to the membrane. PMID:27218137

  19. Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

    KAUST Repository

    Geise, Geoffrey M.

    2013-10-23

    Salinity gradient energy technologies, such as reverse electrodialysis (RED) and capacitive mixing based on Donnan potential (Capmix CDP), could help address the global need for noncarbon-based energy. Anion exchange membranes (AEMs) are a key component in these systems, and improved AEMs are needed in order to optimize and extend salinity gradient energy technologies. We measured ionic resistance and permselectivity properties of quaternary ammonium-functionalized AEMs based on poly(sulfone) and poly(phenylene oxide) polymer backbones and developed structure-property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend on the volume fraction of water in the polymer membrane, and the chemical nature of the polymer itself can influence fine-tuning of the transport properties to obtain membranes with other useful properties, such as chemical and dimensional stability. The ionic resistance of the AEMs considered in this study decreased by more than 3 orders of magnitude (i.e., from 3900 to 1.6 Ω m) and the permselectivity decreased by 6% (i.e., from 0.91 to 0.85) as the volume fraction of water in the polymer was varied by a factor of 3.8 (i.e., from 0.1 to 0.38). Water content was used to rationalize a tradeoff relationship between the permselectivity and ionic resistance of these AEMs whereby polymers with higher water content tend to have lower ionic resistance and lower permselectivity. The correlation of ion transport properties with water volume fraction and fixed charge concentration is discussed with emphasis on the importance of considering water volume fraction when interpreting ion transport data. © 2013 American Chemical Society.

  20. Anion exchange purification of plasmid DNA using expanded bed adsorption.

    Science.gov (United States)

    Ferreira, G N; Cabral, J M; Prazeres, D M

    2000-01-01

    Recent developments in gene therapy with non-viral vectors and DNA vaccination have increased the demand for large amounts of pharmaceutical-grade plasmid DNA. The high viscosity of process streams is of major concern in the purification of plasmids, since it can cause high back pressures in column operations, thus limiting the throughput. In order to avoid these high back pressures, expanded bed anion exchange chromatography was evaluated as an alternative to fixed bed chromatography. A Streamline 25 column filled with 100 ml of Streamline QXL media, was equilibrated with 0.5 M NaCl in TE (10 mM Tris, 1 mM EDTA, pH = 8.0) buffer at an upward flow of 300 cmh-1, E. coli lysates (obtained from up to 3 liters of fermentation broth) were injected in the column. After washing out the unbound material, the media was allowed to sediment and the plasmid was eluted with 1 M NaCl in TE buffer at a downward flow of 120 cmh-1. Purification factors of 36 +/- 1 fold, 26 +/- 0.4 plasmid purity, and close to 100% yields were obtained when less than one settled column volume of plasmid feed was injected. However, both recovery yield and purity abruptly decreased when larger amounts were processed-values of 35 +/- 2 and 5 +/- 0.7 were obtained for the recovery yield and purity, respectively, when 250 ml of feedstock were processed. In these cases, gel clogging and expansion collapse were observed. The processing of larger volumes, thus larger plasmid quantities, was only possible by performing an isopropanol precipitation step prior to the chromatographic step. This step led to an enhancement of the purification step.

  1. Anion exchange resin as support for invertase immobilization

    Directory of Open Access Journals (Sweden)

    M. Vitolo

    2009-01-01

    Full Text Available

    The invertase (EC 3.2.1.26 from Saccharomyces cerevisiae was employed as a model enzyme in the evaluation of the adsorption capacity of DOWEX-1X8-50®, a basic anion exchange resin, when used as support in enzyme immobilization. By mixing 100mg of resin with 27mg of invertase (pI = 4.0 in buffer solution (pH 4.6, 25°C, stirred at 100rpm, an adsorption of 93% was achieved. The activities (1U = amount of enzyme forming 1mg reducing sugars/min of soluble and insoluble invertase were 0.084 U/mgE and 0.075 U/mgE, respectively, giving an immobilization coefficient of 90.4%. The immobilized invertase had a higher thermal stability than the soluble form. The highest activity was observed at pH 4.5 in both forms of the enzyme, whereas the pH stability ranges for soluble and insoluble invertase were 3.5-5.0 and 4.5-5.5, respectively. The kinetic constants for soluble invertase were KM = 18.3 mM and Vmax = 0.084 U/mgE, and for the insoluble form, KM = 29.1 mM and Vmax = 0.075 U/mgE. The resin tested adsorbed the invertase very well, provided the enzyme molecule had a net negative charge, i.e., the immobilization and reaction procedures had to be carried out at pH > pI. Keywords: Invertase, immobilization, adsorption, anionexchange resin.

  2. Effect of Competing Anions on Arsenate Adsorption onto Maghemite Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    T. Tuutijarvi; E. Repo; R. Vahala; M. Sillanpaa; G. Chen

    2012-01-01

    This paper reports the effect of several competing anions on arsenate adsorption with maghemite nanoparticles. Sulphate (as SO4), nitrate (as NO3-N), phosphate (as PO4-P) ions and silicate-(as SiO2) were-studied in dual solution with arsenate. Moreover, the combined effect of ions and other water characteristics were examined with a natural groundwater sample which was spiked with a certain amount of arsenate. Arsenate batch adsorption experiments were carried out with two different kinds of maghemite-a commercially, available one and a homemade one using the sol-gel orocess. Sulohate (≤250 mg.L-1) and nitrate (≤ 12 mg.L-1) had a neglivible effect onthe arsenate (0.5 mg.L-1) adsorption at pH 3. However, both phosphate (42.9 mg·L-1) and silicate (450 mg.L-j) had an adverse impact on arsenate (43 mg.L-1) adsorption at pH 7. Phosphate (41.5 mg.L-1) showed minimal competition with arsenate (0.5 mg.L-1), while silicate (410 mg.L-1) inhibition was insignificant for all studied As(V) concentrations at p.H 3. The removal of arsenate from the groundwater sample was as efficient as from labo-ratory water tor 0.3 mgL -1 AS(V) botll at pH3 and pH7.

  3. Induction of Apoptosis by Superoxide Anion and the Protective Effects of Selenium and Vitamin E

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective The purpose of this study is to investigate the effect of superoxide anion on the apoptosis of cultured fibroblasts and the protective role of selenium and Vitamin E. Methods Cultured fibroblasts (NIH3T3), with or without selenium or vitamin E in the medium, were treated by superoxide anion produced by xanthine/xanthine oxidase reaction system and changes in cell structure and DNA were observed microscopically and electrophoretically. Results Apoptosis was observed when superoxide anion at a concentration of 5 nmol/L or 10 nmol/L had acted on the fibroblasts for 5-10 h. Selenium and Vitamin E in the medium inhibited the apoptosis significantly when their concentrations reached 1.15 mol/L and 2.3 mol/L respectively. Conclusion Selenium and vitamin E have protective effect against the apoptosis induced by superoxide anion. The effect of selenium is more remarkable than that of vitamin E.

  4. OD ESR detection of the radical anions of cyclic nitrones in liquid solutions

    Science.gov (United States)

    Barlukova, M. M.; Gritsan, N. P.; Bagryansky, V. A.; Starichenko, V. F.; Grigor'ev, I. A.; Molin, Yu. N.

    2005-01-01

    The radical anions of five-membered cyclic nitrone spin traps, 3,3,5,5-tetramethyl-1-pyrroline-1-oxide and 1,2,2,5,5-pentamethyl-3-imidazoline-3-oxide, formed under radiolysis of liquid squalane solutions at 250-268 K, were registered by the method of optically detected ESR, and the hfc constants and g-values of the radical anions were determined. The hfc constants of these radical anions were predicted by DFT calculations and were found to be in quantitative agreement with experiment. It was demonstrated that radical anions of the five-membered cyclic nitrones have non-planar geometry with the spin density localized in the C dbnd N sbnd O fragment.

  5. Effects of Hofmeister salt series on gluten network formation: Part II. Anion series.

    Science.gov (United States)

    Tuhumury, H C D; Small, D M; Day, L

    2016-12-01

    Different anion salts from the Hofmeister series were used to investigate their effects on gluten network formation. The effects of these anion salts on the mixing properties of the dough and the rheological and chemical properties of gluten samples extracted from the dough with these respective salts were compared. The aim of this work was to determine how different anion salts influence the formation of the gluten structure during dough mixing. It was found that the Hofmeister anion salts affected the gluten network formation by interacting directly with specific amino acid residues that resulted in changes in gluten protein composition, specifically the percentage of the unextractable polymeric protein fractions (%UPP). These changes consequently led to remarkable differences in the mixing profiles and microstructural features of the dough, small deformation rheological properties of the gluten and a strain hardening behaviour of both dough and gluten samples. PMID:27374597

  6. Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

    Science.gov (United States)

    Passos, C. B.; Kuhn, P. S.; Diehl, A.

    2015-11-01

    In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte-cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte-cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA-cationic surfactant complexes.

  7. Aquaporins with anion/monocarboxylate permeability: mechanisms, relevance for pathogen-host interactions

    Directory of Open Access Journals (Sweden)

    Janis eRambow

    2014-09-01

    Full Text Available Classically, aquaporins are divided based on pore selectivity into water specific, orthodox aquaporins and solute-facilitating aquaglyceroporins, which conduct e.g. glycerol and urea. However, more aquaporin-passing substrates have been identified over the years, such as the gases ammonia and carbon dioxide or the water-related hydrogen peroxide, and it became apparent that not all aquaporins clearly fit into one of only two subfamilies. Furthermore, certain aquaporins from both major subfamilies have been reported to conduct inorganic anions, such as chloride, or monoacids/monocarboxylates, such as lactic acid/lactate. Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate-nitrite transporters, and discuss in which scenarios anion conducting aquaporins may be of physiological relevance.

  8. A Simple Colorimetric Procedure for Differentiating Anions Using Flower Pigments from Anthurium andreanum

    Directory of Open Access Journals (Sweden)

    Maynard O. Galingana

    2016-06-01

    Full Text Available A simple, “green” and colorimetric approach in differentiating various anions is presented. Acidified ethanolic extracts from flowers of Anthurium andreanum undergo color changes in the presence of HSO4-, CH3COO-, C6H5COO-, HCO3-, CO32-, HPO42- and PO43- anions in aqueous solutions. Anionic acid-base conjugate pairs such as HCO3- and CO32-, HSO4- and SO42-, and phosphates H2PO4-, HPO42-, and PO43- can also be discriminated from each other. Visible spectroscopic analysis indicates possible structural changes in pigments due to pH change of solution as a consequence of the basic property of anions.

  9. Effect of temperature on O anion radical reactions and equilibria: a pulse radiolysis study

    International Nuclear Information System (INIS)

    The pKa of the hydroxyl radical was measured over the 20-800C temperature range. At 200C, the pKa was 11.84 and fell to 10.81 at 800C. The dissociation constant for the ozonide anion (O2-anion radical ↔ O2 + O anion radical) was found to be 5.5 x 10-7 mol dm-3 at 200C and 46.2 x 10-7 mol dm-3 at 700C. The rate constants and activation energies for the reaction of O anion radical and OH with 2-propanol, methanol and 3-hexene-1,6-dicarboxylate ions have also been measured. (author)

  10. Optical properties of the radical anion derived from {alpha}-alanine by deamination

    Energy Technology Data Exchange (ETDEWEB)

    Zagorski, Z.P.; Przybytniak, G.K. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

    1997-12-31

    The free radical anion CH{sub 3}CHCOO derived during high energy irradiation from {alpha}-alanine by deamination has been investigated until now by EPR, in irradiated single crystals, for basic research or in completely randomized polycrystalline material for {gamma}-dosimetric purposes. It has been found by spectrophotometry of irradiated single crystals that the free radical absorbs light at {lambda}{sub max}=350 nm. The same radical anion is observed by pulse radiolysis of {alpha}-chloropropionic or propionic anion in aqueous solutions by Cl resp. {alpha}-H abstraction.Basic and applied aspects of the identity of the radical anion obtained in different ways are discussed, as well as consequences for dosimetric techniques. (author). 11 refs, 4 figs.

  11. Preparation of anion exchange membrane using polyvinyl chloride (PVC) for alkaline water electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Gab-Jin; Bong, Soo-Yeon; Ryu, Cheol-Hwi [Hoseo University, Asan (Korea, Republic of); Lim, Soo-Gon [Energy and Machinery Korea Co., Ltd., Changwon (Korea, Republic of); Choi, Ho-Sang [Kyungil University, Gyeongsan (Korea, Republic of)

    2015-09-15

    An anion exchange membrane was prepared by the chloromethylation and the amination of polyvinyl chloride (PVC), as the base polymer. The membrane properties of the prepared anion exchange membrane, including ionic conductivity, ion exchange capacity, and water content were measured. The ionic conductivity of the prepared anion exchange membrane was in the range of 0.098x10{sup -2} -7.0x10{sup -2}S cm{sup -1}. The ranges of ion exchange capacity and water content were 1.9-3.7meq./g-dry-membrane and 35.1-63.1%, respectively. The chemical stability of the prepared anion exchange membrane was tested by soaking in 30 wt% KOH solution to determine its availability as a separator in the alkaline water electrolysis. The ionic conductivity during the chemical stability test largely did not change.

  12. Neutral, anionic, cationic, and zwitterionic diblock copolymers featuring poly(2-methoxyethyl acrylate) hydrophobic segments

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    Amphiphilic diblock copolymers incorporating hydrophobic poly(2-methoxyethyl acrylate) (PMEA) and hydrophilic neutral poly(ethylene glycol) monomethyl ether (mPEG), anionic poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA...

  13. Urea/thiourea derivatives and Zn(II)-DPA complex as receptors for anionic recognition—A brief account

    Indian Academy of Sciences (India)

    Priyadip Das; Prasenjit Mahato; Amrita Ghosh; Amal K Mandal; Tanmay Banerjee; Sukdeb Saha; Amitava Das

    2011-03-01

    This review covers few examples of anion complexation chemistry, with a special focus on urea/thiourea-based receptors and Zn(II)-dipicolyl amine-based receptors. This article specially focuses on structural aspects of the receptors and the anions for obtaining the desire specificity along with an efficient receptor-anion interaction. Two types of receptors have been described in this brief account; first one being the strong hydrogen bond donor urea/thiourea derivatives, which binds the anionic analytes through hydrogen bonded interactions; while, the second type of receptors are coordination complexes, where the coordination of the anion to the metal centre. In both the cases the anion binding modulate the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and thereby the spectroscopic response. Appropriate choice of the signalling unit may allow probing the anion binding phenomena through visual detection.

  14. Near-Threshold Photodetachment Cross Section of (SF6)(n)(-) Cluster Anions: The Ion Core Structure.

    Science.gov (United States)

    Luzon, Itamar; Nagler, Maoz; Chandrasekaran, Vijayanand; Heber, Oded; Strasser, Daniel

    2016-01-21

    Photodetachment cross sections as a function of photon energy are measured for cold (SF6)n(-) cluster anions stored in an electrostatic ion beam trap. Absolute photodetachment cross sections near the adiabatic limit are reported. The strong dependence of the SF6(-) absolute photodetachment cross section on the anion equilibrium bond length leads to the conclusion that the excess charge is localized on a SF6(-) ion core that is only subtly perturbed by the neighboring cluster units. PMID:26667587

  15. Membrane Separator for Redox Flow Batteries that Utilize Anion Radical Mediators.

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

    A Na + ion conducting polyethylene oxide membrane is developed for an organic electrolyte redox flow battery that utilizes anion radical mediators. To achieve high specific ionic conductivity, tetraethyleneglycol dimethylether (TEGDME) is used as a plasticizer to reduce crystallinity and increase the free volume of the gel film. This membrane is physically and chemically stable in TEGDME electrolyte that contains highly reactive biphenyl anion radical mediators.

  16. Determination of common anions in oxalate by ion chromatography coupled with UV photolysis pretreatment

    Institute of Scientific and Technical Information of China (English)

    Sheng Lin Cao; Ming Li Ye; Wei De Lv; Guang Wen Pan; Ting Ting Zhang; Zhong Yang Hu; Li Na Liang; Yan Zhu

    2012-01-01

    A new and simple method was developed to determine anions in oxalate of analytical reagent grade.After UV photolysis with optimal 1% H2O2 in 10,000 mg/L oxalate in the fabricated photoreactor,sample was directly injected into IC system.Satisfactory linearity,detections limits,good repeatability and spiked recovery were obtained.The method was successfully applied to determine anions in two commercial oxalate samples.

  17. Carborane Anions: As Weakly Coordinating Counterions and Coordinating Ligands for Catalyst Design

    OpenAIRE

    Wright, James Henry

    2013-01-01

    1-carba-closo-dodecaborates, more commonly referred to as carborane anions, are icosahedral CB11 cages with substituents at each vertex. These substituents are highly variable allowing for a large range of properties. Such properties include being weakly basic, chemically inert, non-nucleophilic, and resistant to reduction or oxidation. Due to these properties, carborane anions have been given the term "weakly coordinating" to describe their interactions with cations. The isolation of numerou...

  18. Effects on anionic salts in a pre-partum dairy ration on calcium metabolism

    OpenAIRE

    C.J. Van Dijk; D.C. Lourens

    2001-01-01

    The effects of anionic salts in the transition diet on serum and urine calcium at calving and on peripartal health, subsequent milk production and fertility performance were studied in a well-managed, high-producing Friesland dairy herd. Over a period of a year, approximately 21 days before the expected date of calving, 28 pre-partum heifers and 44 multiparous dry cows were randomly allocated within parity to 1 of 2 transition diets, designated control and experimental anionic diets. The anio...

  19. Parent Anions of Iron, Manganese, and Nickel Tetraphenyl Porphyrins: Photoelectron Spectroscopy and Computations.

    Science.gov (United States)

    Buytendyk, Allyson M; Graham, Jacob D; Gould, Julian; Bowen, Kit H

    2015-08-13

    The singly charged, parent anions of three transition metal, tetraphenyl porphyrins, M(TPP) [Fe(TPP), Mn(TPP), and Ni(TPP)], were studied by negative ion photoelectron spectroscopy. The observed (vertical) transitions from the ground state anions of these porphyrins to the various electronic states of their neutral counterparts were modeled by density functional theory computations. Our experimental and theoretical results were in good agreement. PMID:26186172

  20. Research on the Microstructure and Property of an Anion Rubber Modified Asphalt

    OpenAIRE

    Wei Hong; Qingshan Li; Guoquan Guan; Youbo Di; Jing Sun; Tifeng Jiao; Guangzhong Xing

    2013-01-01

    The anion rubber modified asphalt (ARMA) mixture was first successfully developed with a unique process. In the development process, rubber and asphalt were mixed in the same proportion. Furthermore, the microstructure and modification mechanism of the material were characterized by SEM, FT-IR, TG, and XRD tests. The mechanical property of the mixture was also tested in accordance with the relevant standards. In the end, the material’s capacity of releasing anion was measured by DLY-6A232 atm...

  1. Further development of capillary electrophoresis for the quantitative determination of small inorganic anions

    OpenAIRE

    King, Marion

    2003-01-01

    Factors influencing the separation and indirect UV absorbance detection of common inorganic anions using capillary zone electrophoresis (CZE) have been investigated. Initially a number of different aspects of indirect background electrolyte (BGE) systems were studied, with the resultant observations indicating the requirements of an 'ideal' BGE system for the separation and detection of common inorganic anions in water samples. In addition to the above the correct use of buffers within BGE us...

  2. Calcium-regulated anion channels in the plasma membrane of Lilium longiflorum pollen protoplasts.

    Science.gov (United States)

    Tavares, Bárbara; Dias, Pedro Nuno; Domingos, Patrícia; Moura, Teresa Fonseca; Feijó, José Alberto; Bicho, Ana

    2011-10-01

    • Currents through anion channels in the plasma membrane of Lilium longiflorum pollen grain protoplasts were studied under conditions of symmetrical anionic concentrations by means of patch-clamp whole-cell configuration. • With Cl(-) -based intra- and extracellular solutions, three outward-rectifying anion conductances, I(Cl1) , I(Cl2) and I(Cl3) , were identified. These three activities were discriminated by differential rundown behaviour and sensitivity to 5-nitro-2-(phenylpropylamino)-benzoate (NPPB), which could not be attributed to one or more channel types. All shared strong outward rectification, activated instantaneously and displayed a slow time-dependent activation for positive potentials. All showed modulation by intracellular calcium ([Ca(2+) ](in) ), increasing intensity from 6.04 nM up to 0.5 mM (I(Cl1) ), or reaching a maximum value with 8.50 μM (I(Cl2) and I(Cl3) ). • After rundown, the anionic currents measured using NO(3) (-) -based solutions were indistinguishable, indicating that the permeabilities of the channels for Cl(-) and NO(3) (-) are similar. Additionally, unitary anionic currents were measured from outside-out excised patches, confirming the presence of individual anionic channels. • This study shows for the first time the presence of a large anionic conductance across the membrane of pollen protoplasts, resulting from the presence of Ca(2+) -regulated channels. A similar conductance was also found in germinated pollen. We hypothesize that these putative channels may be responsible for the large anionic fluxes previously detected by means of self-referencing vibrating probes. PMID:21668885

  3. Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

    Science.gov (United States)

    Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

    2014-10-22

    The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation.

  4. The Anion Gap is a Predictive Clinical Marker for Death in Patients with Acute Pesticide Intoxication.

    Science.gov (United States)

    Lee, Sun-Hyo; Park, Samel; Lee, Jung-Won; Hwang, Il-Woong; Moon, Hyung-Jun; Kim, Ki-Hwan; Park, Su-Yeon; Gil, Hyo-Wook; Hong, Sae-Yong

    2016-07-01

    Pesticide formulation includes solvents (methanol and xylene) and antifreeze (ethylene glycol) whose metabolites are anions such as formic acid, hippuric acid, and oxalate. However, the effect of the anion gap on clinical outcome in acute pesticide intoxication requires clarification. In this prospective study, we compared the anion gap and other parameters between surviving versus deceased patients with acute pesticide intoxication. The following parameters were assessed in 1,058 patients with acute pesticide intoxication: blood chemistry (blood urea nitrogen, creatinine, glucose, lactic acid, liver enzymes, albumin, globulin, and urate), urinalysis (ketone bodies), arterial blood gas analysis, electrolytes (Na(+), K(+), Cl(-) HCO3 (-), Ca(++)), pesticide field of use, class, and ingestion amount, clinical outcome (death rate, length of hospital stay, length of intensive care unit stay, and seriousness of toxic symptoms), and the calculated anion gap. Among the 481 patients with a high anion gap, 52.2% had a blood pH in the physiologic range, 35.8% had metabolic acidosis, and 12.1% had acidemia. Age, anion gap, pesticide field of use, pesticide class, seriousness of symptoms (all P < 0.001), and time lag after ingestion (P = 0.048) were significant risk factors for death in univariate analyses. Among these, age, anion gap, and pesticide class were significant risk factors for death in a multiple logistic regression analysis (P < 0.001). In conclusions, high anion gap is a significant risk factor for death, regardless of the accompanying acid-base balance status in patients with acute pesticide intoxication. PMID:27366016

  5. Anionic Lipids Enriched at the ExPortal of Streptococcus pyogenes▿

    OpenAIRE

    Rosch, Jason W.; Hsu, Fong Fu; Caparon, Michael G.

    2006-01-01

    The ExPortal of Streptococcus pyogenes is a membrane microdomain dedicated to the secretion and folding of proteins. We investigated the lipid composition of the ExPortal by examining the distribution of anionic membrane phospholipids. Staining with 10-N-nonyl-acridine orange revealed a single microdomain enriched with an anionic phospholipid whose staining characteristics and behavior in a cardiolipin-deficient mutant were characteristic of phosphatidylglycerol. Furthermore, the location of ...

  6. Specific adsorption of perchlorate anions on Pt{hkl} single crystal electrodes.

    Science.gov (United States)

    Attard, Gary A; Brew, Ashley; Hunter, Katherine; Sharman, Jonathan; Wright, Edward

    2014-07-21

    The voltammetry of Pt{111}, Pt{100}, Pt{110} and Pt{311} single crystal electrodes as a function of perchloric acid concentration (0.05-2.00 M) has been studied in order to test the assertion made in recent reports by Watanabe et al. that perchlorate anions specifically adsorb on polycrystalline platinum. Such an assertion would have significant ramifications for our understanding of electrocatalytic processes at platinum surfaces since perchlorate anions at low pH have classically been assumed not to specifically adsorb. For Pt{111}, it is found that OHad and electrochemical oxide states are both perturbed significantly as perchloric acid concentration is increased. We suggest that this is due to specific adsorption of perchlorate anions competing with OHad for adsorption sites. The hydrogen underpotential deposition (H UPD) region of Pt{111} however remains unchanged although evidence for perchlorate anion decomposition to chloride on Pt{111} is reported. In contrast, for Pt{100} no variation in the onset of electrochemical oxide formation is found nor any shift in the potential of the OHad state which normally results from the action of specifically adsorbing anions. This suggests that perchlorate anions are non-specifically adsorbed on this plane although strong changes in all H UPD states are observed as perchloric acid concentration is increased. This manifests itself as a redistribution of charge from the H UPD state situated at more positive potential to the one at more negative potential. For Pt{110} and Pt{311}, marginal changes in the onset of electrochemical oxide formation are recorded, associated with specific adsorption of perchlorate. Specific adsorption of perchlorate anions on Pt{111} is deleterious to electrocatalytic activity in relation to the oxygen reduction reaction (ORR) as measured using a rotating disc electrode (RDE) in a hanging meniscus configuration. This study supports previous work suggesting that a large component of the ORR

  7. Anion-dipole interactions make the homopolymers self-assemble into multiple nanostructures.

    Science.gov (United States)

    Wang, Long-Hai; Zhang, Zi-Dan; Hong, Chun-Yan; He, Xue-Hao; You, Wei; You, Ye-Zi

    2015-05-27

    Anion-dipole interactions can make homopolymers self-assemble like an amphiphilic block copolymer. Generally, common homopolymers cannot self-assemble into multiple nanostructures. Here, it is reported that anion-dipole interactions can enable a number of homopolymers to achieve a variety of self-assembly behaviors in aqueous solution. Such interactions and self-assembly features have been exclusively reserved for amphiphilic (block) polymers until now. PMID:25873566

  8. Method of removing arsenic and other anionic contaminants from contaminated water using enhanced coagulation

    Science.gov (United States)

    Teter, David M.; Brady, Patrick V.; Krumhansl, James L.; Khandaker, Nadim R.

    2006-11-21

    An improved water decontamination process comprising contacting water containing anionic contaminants with an enhanced coagulant to form an enhanced floc, which more efficiently binds anionic species (e.g., arsenate, arsenite, chromate, fluoride, selenate, and borate, and combinations thereof) predominantly through the formation of surface complexes. The enhanced coagulant comprises a trivalent metal cation coagulant (e.g., ferric chloride or aluminum sulfate) mixed with a divalent metal cation modifier (e.g., copper sulfate or zinc sulfate).

  9. Generation of aliphatic acid anions and carbon dioxide by hydrous pyrolysis of crude oils

    Science.gov (United States)

    Kharaka, Y.K.; Lundegard, P.D.; Ambats, G.; Evans, William C.; Bischoff, J.L.

    1993-01-01

    Two crude oils with relatively high (0.60 wt%) and low (0.18 wt%) oxygen contents were heated in the presence of water in gold-plated reactors at 300??C for 2348 h. The high-oxygen oil was also heated at 200??C for 5711 h. The compositions of aqueous organic acid anions of the oils and of the headspace gases were monitored inn order to investigate the distribution of organic acids that can be generated from liquid petroleum. The oil with higher oxygen content generated about five times as much organic anions as the other oil. The dominant organic anions produced were acetate, propionate and butyrate. Small amounts of formate, succinate, methyl succinate and oxalate were also produced. The dominant oxygen-containing product was CO2, as has been observed in similar studies on the hydrous pyrolysis of kerogen. These results indicate that a significant portion (10-30%) of organic acid anions reported i be generated by thermal alteration of oils in reservoir rocks. The bulk of organic acid anions present in formation waters, however, is most likely generated by thermal alteration of kerogen in source rocks. Kerogen is more abundant than oil in sedimentary basins and the relative yields of organic acid anions reported from the hydrous pyrolysis of kerogen are much higher than the yields obtained for the two oils. ?? 1993.

  10. Organic anion transporter (Slc22a) family members as mediators of toxicity

    International Nuclear Information System (INIS)

    Exposure of the body to toxic organic anions is unavoidable and occurs from both intentional and unintentional sources. Many hormones, neurotransmitters, and waste products of cellular metabolism, or their metabolites, are organic anions. The same is true for a wide variety of medications, herbicides, pesticides, plant and animal toxins, and industrial chemicals and solvents. Rapid and efficient elimination of these substances is often the body's best defense for limiting both systemic exposure and the duration of their pharmacological or toxicological effects. For organic anions, active transepithelial transport across the renal proximal tubule followed by elimination via the urine is a major pathway in this detoxification process. Accordingly, a large number of organic anion transport proteins belonging to several different gene families have been identified and found to be expressed in the proximal nephron. The function of these transporters, in combination with the high volume of renal blood flow, predisposes the kidney to increased toxic susceptibility. Understanding how the kidney mediates the transport of organic anions is integral to achieving desired therapeutic outcomes in response to drug interactions and chemical exposures, to understanding the progression of some disease states, and to predicting the influence of genetic variation upon these processes. This review will focus on the organic anion transporter (OAT) family and discuss the known members, their mechanisms of action, subcellular localization, and current evidence implicating their function as a determinant of the toxicity of certain endogenous and xenobiotic agents

  11. Biliary secretion of organic anions in the dog: association with defined lipid particles

    International Nuclear Information System (INIS)

    Organic anions have recently been found to partition in vitro into various biliary lipid particulate species according to their relative hydrophobicities. To establish the physiological relevance of these observations, we intravenously injected various radiolabeled organic anions and assessed the distributions of parent compounds and their metabolites to lipid particles in canine bile. Partitioning into various biliary lipid particles was determined by gel permeation chromatography. Relative hydrophobicities of the various organic anions and their radiolabeled conjugates were determined by reverse-phase high-pressure liquid chromatography. A strong positive correlation (P less than 0.001) was found between percent vesicular association and degree of hydrophobicity for a given organic anion and/or its more polar conjugate. We conclude that 1) the hydrophobic-hydrophilic balance of organic anions is a key factor governing their partitioning to lipid particles secreted in bile; 2) the present study agrees well with our previously published in vitro observations; and 3) other chemical constituents, e.g., proteins, mucin, etc., appear to have little or no effect on organic anion transport in bile

  12. Research on the Microstructure and Property of an Anion Rubber Modified Asphalt

    Directory of Open Access Journals (Sweden)

    Wei Hong

    2013-01-01

    Full Text Available The anion rubber modified asphalt (ARMA mixture was first successfully developed with a unique process. In the development process, rubber and asphalt were mixed in the same proportion. Furthermore, the microstructure and modification mechanism of the material were characterized by SEM, FT-IR, TG, and XRD tests. The mechanical property of the mixture was also tested in accordance with the relevant standards. In the end, the material’s capacity of releasing anion was measured by DLY-6A232 atmospheric ion gauge. The results indicated that the addition of anion additive into the rubber modified asphalt (RMA was a mere physical mixture, and the anion additives and rubber particles uniformly dispersed in the ARMA. The addition of anion additive could improve the thermal stability of the RMA. Compared with the traditional asphalt pavement material, the ARMA material shows excellent mechanical properties as well as the ability of releasing anion. Moreover, the material has enormous economic and social benefits by taking full advantage of a large amount of waste tires, thus improving the road surrounding environment.

  13. Tuning the optical properties of 2-thienylpyridyl iridium complexes through carboranes and anions.

    Science.gov (United States)

    Zhu, Lin; Tang, Xiao; Yu, Qi; Lv, Wen; Yan, Hong; Zhao, Qiang; Huang, Wei

    2015-03-16

    2-Thienylpyridyl iridium(III) complexes containing an o-, m-, or p-carboranylvinyl-2,2'-bipyridine ligand and various counteranions (denoted o-PF6, m-BF4, m-PF6, m-SbF6, m-ClO4, m-OTf, m-NO3, m-BPh4, m-F, m-Cl, and p-PF6) were synthesized by using C-formyl carboranes as starting materials. The solid-state structures of o-PF6, m-PF6, m-ClO4, and m-BF4 showed that the cations form twisted cavities in which the anions are fixed by multiple hydrogen bonds. Anion-hydrogen interactions were investigated for nine m-carborane-based complexes with different counteranions. All carborane-based iridium(III) complexes show similar phosphorescence yields in solution but significantly different emission in the solid state. Anion-exchange titration and theoretical calculations revealed the relationships between structures and optical properties. The size of the anion and C-H⋅⋅⋅X anion-hydrogen bonds strongly influence the phosphorescence quantum yield in the solid state. In particular, the Ccar-H⋅⋅⋅X hydrogen bonds between the carboranyl unit and the anion play an important role in solid-state phosphorescence. Complex p-PF6 was successfully applied in phosphorescence-lifetime bioimaging owing to its low toxicity and near-infrared emission. PMID:25663604

  14. Acetate and phosphate anion adsorption linear sweep voltammograms simulated using density functional theory

    KAUST Repository

    Savizi, Iman Shahidi Pour

    2011-04-01

    Specific adsorption of anions to electrode surfaces may alter the rates of electrocatalytic reactions. Density functional theory (DFT) methods are used to predict the adsorption free energy of acetate and phosphate anions as a function of Pt(1 1 1) electrode potential. Four models of the electrode potential are used including a simple vacuum slab model, an applied electric field model with and without the inclusion of a solvating water bi-layer, and the double reference model. The linear sweep voltammogram (LSV) due to anion adsorption is simulated using the DFT results. The inclusion of solvation at the electrochemical interface is necessary for accurately predicting the adsorption peak position. The Langmuir model is sufficient for predicting the adsorption peak shape, indicating coverage effects are minor in altering the LSV for acetate and phosphate adsorption. Anion adsorption peak positions are determined for solution phase anion concentrations present in microbial fuel cells and microbial electrolysis cells and discussion is provided as to the impact of anion adsorption on oxygen reduction and hydrogen evolution reaction rates in these devices. © 2011 Elsevier Ltd. All rights reserved.

  15. Structure of cyano-anion ionic liquids: X-ray scattering and simulations.

    Science.gov (United States)

    Dhungana, Kamal B; Faria, Luiz F O; Wu, Boning; Liang, Min; Ribeiro, Mauro C C; Margulis, Claudio J; Castner, Edward W

    2016-07-14

    Ionic liquids with cyano anions have long been used because of their unique combination of low-melting temperatures, reduced viscosities, and increased conductivities. Recently we have shown that cyano anions in ionic liquids are particularly interesting for their potential use as electron donors to excited state photo-acceptors [B. Wu et al., J. Phys. Chem. B 119, 14790-14799 (2015)]. Here we report on bulk structural and quantum mechanical results for a series of ionic liquids based on the 1-ethyl-3-methylimidazolium cation, paired with the following five cyano anions: SeCN(-), SCN(-), N(CN)2 (-), C(CN)3 (-), and B(CN)4 (-). By combining molecular dynamics simulations, high-energy X-ray scattering measurements, and periodic boundary condition DFT calculations, we are able to obtain a comprehensive description of the liquid landscape as well as the nature of the HOMO-LUMO states for these ionic liquids in the condensed phase. Features in the structure functions for these ionic liquids are somewhat different than the commonly observed adjacency, charge-charge, and polarity peaks, especially for the bulkiest B(CN)4 (-) anion. While the other four cyano-anion ionic liquids present an anionic HOMO, the one for Im2,1 (+)/B(CN)4 (-) is cationic.

  16. The viability of aluminum Zintl anion moieties within magnesium-aluminum clusters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Jae Ko, Yeon; Zhang, Xinxing; Gantefoer, Gerd; Bowen, Kit H., E-mail: kiran@mcneese.edu, E-mail: akandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnoeckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States); Jena, Puru [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kiran, Boggavarapu, E-mail: kiran@mcneese.edu, E-mail: akandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K., E-mail: kiran@mcneese.edu, E-mail: akandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-03-28

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have investigated the extent to which the aluminum moieties within selected magnesium-aluminum clusters are Zintl anions. Magnesium-aluminum cluster anions were generated in a pulsed arc discharge source. After mass selection, photoelectron spectra of Mg{sub m}Al{sub n}{sup −} (m, n = 1,6; 2,5; 2,12; and 3,11) were measured by a magnetic bottle, electron energy analyzer. Calculations on these four stoichiometries provided geometric structures and full charge analyses for the cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra). Calculations revealed that, unlike the cases of recently reported sodium-aluminum clusters, the formation of aluminum Zintl anion moieties within magnesium-aluminum clusters was limited in most cases by weak charge transfer between the magnesium atoms and their aluminum cluster moieties. Only in cases of high magnesium content, e.g., in Mg{sub 3}Al{sub 11} and Mg{sub 2}Al{sub 12}{sup −}, did the aluminum moieties exhibit Zintl anion-like characteristics.

  17. Structure of cyano-anion ionic liquids: X-ray scattering and simulations

    Science.gov (United States)

    Dhungana, Kamal B.; Faria, Luiz F. O.; Wu, Boning; Liang, Min; Ribeiro, Mauro C. C.; Margulis, Claudio J.; Castner, Edward W.

    2016-07-01

    Ionic liquids with cyano anions have long been used because of their unique combination of low-melting temperatures, reduced viscosities, and increased conductivities. Recently we have shown that cyano anions in ionic liquids are particularly interesting for their potential use as electron donors to excited state photo-acceptors [B. Wu et al., J. Phys. Chem. B 119, 14790-14799 (2015)]. Here we report on bulk structural and quantum mechanical results for a series of ionic liquids based on the 1-ethyl-3-methylimidazolium cation, paired with the following five cyano anions: SeCN-, SCN-, N(CN) 2 -, C(CN) 3 -, and B(CN) 4 -. By combining molecular dynamics simulations, high-energy X-ray scattering measurements, and periodic boundary condition DFT calculations, we are able to obtain a comprehensive description of the liquid landscape as well as the nature of the HOMO-LUMO states for these ionic liquids in the condensed phase. Features in the structure functions for these ionic liquids are somewhat different than the commonly observed adjacency, charge-charge, and polarity peaks, especially for the bulkiest B(CN) 4 - anion. While the other four cyano-anion ionic liquids present an anionic HOMO, the one for Im2,1 +/B(CN) 4 - is cationic.

  18. Valence-bound and diffuse-bound anions of 5-azauracil.

    Science.gov (United States)

    Corzo, H H; Dolgounitcheva, O; Zakrzewski, V G; Ortiz, J V

    2014-08-28

    Structures, isomerization energies, and electron binding energies of 5-azauracil and its anions have been calculated ab initio with perturbative, coupled-cluster, and electron-propagator methods. Tautomeric structures, including those produced by proton transfer to a CH group, have been considered. Dyson orbitals and pole strengths from electron-propagator calculations validated a simple, molecular-orbital picture of anion formation. In one case, an electron may enter a delocalized π orbital, yielding a valence-bound (VB) anion with a puckered ring structure. The corresponding electron affinity is 0.27 eV; the vertical electron detachment energy (VEDE) of this anion 1.05 eV. An electron also may enter a molecular orbital that lies outside the nuclear framework, resulting in a diffuse-bound (DB) anion. In the latter case, the electron affinity is 0.06 eV and the VEDE of the DB anion is 0.09 eV. Another VB isomer that is only 0.02 eV more stable than the neutral molecule has a VEDE of 2.0 eV. PMID:25102270

  19. Organic anion transporter 3- and organic anion transporting polypeptides 1B1- and 1B3-mediated transport of catalposide

    Directory of Open Access Journals (Sweden)

    Jeong HU

    2015-01-01

    Full Text Available Hyeon-Uk Jeong,1 Mihwa Kwon,2 Yongnam Lee,3 Ji Seok Yoo,3 Dae Hee Shin,3 Im-Sook Song,2 Hye Suk Lee1 1College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea; 2College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 702-701, Korea; 3Central R&D Institute, Yungjin Pharm Co., Ltd., Suwon 443-270, Korea Abstract: We investigated the in vitro transport characteristics of catalposide in HEK293 cells overexpressing organic anion transporter 1 (OAT1, OAT3, organic anion transporting polypeptide 1B1 (OATP1B1, OATP1B3, organic cation transporter 1 (OCT1, OCT2, P-glycoprotein (P-gp, and breast cancer resistance protein (BCRP. The transport mechanism of catalposide was investigated in HEK293 and LLC-PK1 cells overexpressing the relevant transporters. The uptake of catalposide was 319-, 13.6-, and 9.3-fold greater in HEK293 cells overexpressing OAT3, OATP1B1, and OATP1B3 transporters, respectively, than in HEK293 control cells. The increased uptake of catalposide via the OAT3, OATP1B1, and OATP1B3 transporters was decreased to basal levels in the presence of representative inhibitors such as probenecid, furosemide, and cimetidine (for OAT3 and cyclosporin A, gemfibrozil, and rifampin (for OATP1B1 and OATP1B3. The concentration-dependent OAT3-mediated uptake of catalposide revealed the following kinetic parameters: Michaelis constant (Km =41.5 µM, maximum uptake rate (Vmax =46.2 pmol/minute, and intrinsic clearance (CLint =1.11 µL/minute. OATP1B1- and OATP1B3-mediated catalposide uptake also showed concentration dependency, with low CLint values of 0.035 and 0.034 µL/minute, respectively. However, the OCT1, OCT2, OAT1, P-gp, and BCRP transporters were apparently not involved in the uptake of catalposide into cells. In addition, catalposide inhibited the transport activities of OAT3, OATP1B1, and OATP1B3 with half-maximal inhibitory concentration values of 83, 200, and 235 µ

  20. Synthesis and structural characterization of anion complexes with azacalix[2]dipyrrolylmethane: effect of anion charge on the conformation of the macrocycle.

    Science.gov (United States)

    Guchhait, Tapas; Mani, Ganesan; Schulzke, Carola

    2016-08-01

    Tetrahomodiazacalix[2]dipyrrolylmethane 1, [-CH2(C4H3N)CR2(C4H3N)CH2N(Me)-]2 an expanded version of the calix[4]pyrrole system, has the tendency to change its ring conformation (1,3-alternate) upon anion binding analogous to calix[4]pyrrole. However, owing to its tertiary amine nitrogen atoms in the ring, it can be protonated and becomes a powerful cationic receptor for anions, besides its inherent hydrogen bonding features. Macrocycle 1 binds with a series of monoanions BF4(-), Cl(-), PhCOO(-) and ClO4(-), and their X-ray structures showed that the ring conformation constitutes the 1,2-alternate form. Upon binding with dianions SO4(2-), CrO4(2-), SiF6(2-) and S2O3(2-), the ring conformation changes to the cone conformation. The intermediate partial cone conformation results for complexes with NO3(-) and Cr2O7(2-) ions. The change in the orientation of the pyrrole NH groups depending on the charge of the anion demonstrates the flexibility of the macrocycle and the dicationic macrocycle stabilizes the anions via both hydrogen bonding and electrostatic interactions. PMID:27356484

  1. Osazone anion radical complex of rhodium(III).

    Science.gov (United States)

    Patra, Sarat Chandra; Biswas, Manas Kumar; Maity, Amarendra Nath; Ghosh, Prasanta

    2011-02-21

    One electron paramagnetic parent osazone complex of rhodium of type trans-Rh(L(NHPh)H(2))(PPh(3))(2)Cl(2) (1), defined as an osazone anion radical complex of rhodium(III), trans-Rh(III)(L(NHPh)H(2)(•-))(PPh(3))(2)Cl(2), 1((t-RhL•)), with a minor contribution (∼2%) of rhodium(II) electromer, trans-Rh(II)(L(NHPh)H(2))(PPh(3))(2)Cl(2), 1((t-Rh•L)), and their nonradical congener, trans-[Rh(III)(L(NHPh)H(2))(PPh(3))(2)Cl(2)]I(3) ([t-1](+)I(3)(-)), have been isolated and are substantiated by spectra, bond parameters, and DFT calculations on equivalent soft complexes [Rh(L(NHPh)H(2))(PMe(3))(2)Cl(2)] (3) and [Rh(L(NHPh)H(2))(PMe(3))(2)Cl(2)](+) (3(+)). 1 is not stable in solution and decomposes to [t-1](+) and a new rhodium(I) osazone complex, [Rh(I)(L(NHPh)H(2))(PPh(3))Cl] (2). 1 absorbs strongly at 351 nm due to MLCT and LLCT, while [t-1](+) and 2 absorb moderately in the range of 300-450 nm, respectively, due to LMCT and MLCT elucidated by TD-DFT calculations on 3((t-RhL•)), [t-3](+), and Rh(I)(L(NHPh)H(2))(PMe(3))Cl (4). EPR spectra of solids at 295 and 77 K, and dichloromethane-toluene frozen glass at 77 K of 1 are similar with g = 1.991, while g = 2.002 for the solid at 25 K. The EPR signal of 1 in dichloromethane solution is weaker (g = 1.992). In cyclic voltammetry, 1 displays two irreversible one electron transfer waves at +0.13 and -1.22 V, with respect to Fc(+)/Fc coupling, due to oxidation of 1((t-RhL•)) to [t-1](+) at the anode and reduction of rhodium(III) to rhodium(II), i.e., [t-1](+) to electromeric 1((t-Rh•L)) at the cathode. PMID:21261283

  2. The nature of the CO2 (-) radical anion in water.

    Science.gov (United States)

    Janik, Ireneusz; Tripathi, G N R

    2016-04-21

    The reductive conversion of CO2 into industrial products (e.g., oxalic acid, formic acid, methanol) can occur via aqueous CO2 (-) as a transient intermediate. While the formation, structure, and reaction pathways of this radical anion have been modelled for decades using various spectroscopic and theoretical approaches, we present here, for the first time, a vibrational spectroscopic investigation in liquid water, using pulse radiolysis time-resolved resonance Raman spectroscopy for its preparation and observation. Excitation of the radical in resonance with its 235 nm absorption displays a transient Raman band at 1298 cm(-1), attributed to the symmetric CO stretch, which is at ∼45 cm(-1) higher frequency than in inert matrices. Isotopic substitution at C ((13)CO2 (-)) shifts the frequency downwards by 22 cm(-1), which confirms its origin and the assignment. A Raman band of moderate intensity compared to the stronger 1298 cm(-1) band also appears at 742 cm(-1) and is assignable to the OCO bending mode. A reasonable resonance enhancement of this mode is possible only in a bent CO2 (-)(C2v/Cs) geometry. These resonance Raman features suggest a strong solute-solvent interaction, the water molecules acting as constituents of the radical structure, rather than exerting a minor solvent perturbation. However, there is no evidence of the non-equivalence (Cs) of the two CO bonds. A surprising resonance Raman feature is the lack of overtones of the symmetric CO stretch, which we interpret due to the detachment of the electron from the CO2 (-) moiety towards the solvation shell. Electron detachment occurs at the energies of 0.28 ± 0.03 eV or higher with respect to the zero point energy of the ground electronic state. The issue of acid-base equilibrium of the radical, which has been in contention for decades, as reflected in a wide variation in the reported pKa (-0.2 to 3.9), has been resolved. A value of 3.4 ± 0.2 measured in this work is consistent with the vibrational

  3. The nature of the CO2- radical anion in water

    Science.gov (United States)

    Janik, Ireneusz; Tripathi, G. N. R.

    2016-04-01

    The reductive conversion of CO2 into industrial products (e.g., oxalic acid, formic acid, methanol) can occur via aqueous CO2- as a transient intermediate. While the formation, structure, and reaction pathways of this radical anion have been modelled for decades using various spectroscopic and theoretical approaches, we present here, for the first time, a vibrational spectroscopic investigation in liquid water, using pulse radiolysis time-resolved resonance Raman spectroscopy for its preparation and observation. Excitation of the radical in resonance with its 235 nm absorption displays a transient Raman band at 1298 cm-1, attributed to the symmetric CO stretch, which is at ˜45 cm-1 higher frequency than in inert matrices. Isotopic substitution at C (13CO2-) shifts the frequency downwards by 22 cm-1, which confirms its origin and the assignment. A Raman band of moderate intensity compared to the stronger 1298 cm-1 band also appears at 742 cm-1 and is assignable to the OCO bending mode. A reasonable resonance enhancement of this mode is possible only in a bent CO2-(C2v/Cs) geometry. These resonance Raman features suggest a strong solute-solvent interaction, the water molecules acting as constituents of the radical structure, rather than exerting a minor solvent perturbation. However, there is no evidence of the non-equivalence (Cs) of the two CO bonds. A surprising resonance Raman feature is the lack of overtones of the symmetric CO stretch, which we interpret due to the detachment of the electron from the CO2- moiety towards the solvation shell. Electron detachment occurs at the energies of 0.28 ± 0.03 eV or higher with respect to the zero point energy of the ground electronic state. The issue of acid-base equilibrium of the radical, which has been in contention for decades, as reflected in a wide variation in the reported pKa (-0.2 to 3.9), has been resolved. A value of 3.4 ± 0.2 measured in this work is consistent with the vibrational properties, bond structure

  4. THE PEROXYMONOCARBONATE ANIONS AS PULP BLEACHING AGENTS. PART 1. RESULTS WITH LIGNIN MODEL COMPOUNDS AND CHEMICAL PULPS

    Directory of Open Access Journals (Sweden)

    Francis K Attiogbe

    2010-08-01

    Full Text Available The peroxymonocarbonate mono-anion (HCO4─ is generated when the bicarbonate anion is added to a H2O2 solution. The mono-anion is believed to have a pKa value of ca. 10 and as such would start dissociating to the di-anion (CO42─ at pH ca. 8. The mono-anion should demonstrate electrophilic properties, while the di-anion should be a nucleophile. In an alkaline, non-sulfur pulping process such as soda/AQ, Na2CO3 could be obtained from the chemical recovery system and carbonated with CO2 from a flue gas stream to produce NaHCO3. In such a case only H2O2 would need to be purchased to generate the peroxymonocarbonate (PMC anions. Bicarbonate anions could also be produced from the carbonation of solutions containing NaOH, Mg(OH2 or mined Na2CO3. One or both of the PMC anions was found to be effective in oxidizing two lignin model compounds as well as lowering the lignin content of kraft and soda/AQ hardwood pulps. The PMC anions were generated in-situ by NaHCO3 or Na2CO3 + CO2 addition to dilute H2O2 solutions.

  5. Anion retention in soil: Possible application to reduce migration of buried technetium and iodine

    International Nuclear Information System (INIS)

    This report summarizes a literature review of our present knowledge of the anion exchange properties of a number of soils and minerals, which may potentially be used as anion exchangers to retard migration of such anions as iodide (I-), iodate (IO3-) and pertechnetate (TcO4-) away from disposal site. The amorphous clays allophane and imogolite, are found to be among the most important soil components capable of developing appreciable amounts of positive charge for anion exchange even at about neutral pH. Decreases in the SiO2/Al2O3 ratio and soil pH result in an increase in soil AEC. Allophane and imogolite rich soils have an AEC ranging from 1 to 18 meq/100g at pH about 6. Highly weathered soils dominated by Fe and Al oxides and kaolinite may develop a significant amount of AEC as soil pH falls. The retention of iodine (I) and technetium (Tc), by soils is associated with both soil organic matter, and Fe and Al oxides, whereas sorption on layer silicate minerals in negligible. Fe and Al oxides become more important in the retention of anionic I-, IO3-, and TcO4- as pH falls, since more positive charge is developed on the oxide surfaces. Although few studies, if any, have been conducted on I and Tc sorption by soil allophane and imogolite, it is estimated that a surface plough soil (2 million pounds soil per acre) with 5 meq/100g AEC, as is commonly found in andisols, shall retain approximately 5900 kg I and 4500 kg Tc. It is conceivable that an anion exchanger such as an andisol could be used to modify the near field environment of a radioactive waste disposal facility. This whole disposal system would then offer similar migration resistance to anions as is normally afforded to cations by usual and normal soils. 93 refs., 10 figs., 7 tabs

  6. Significance of anion exchange in pentachlorophenol sorption by variable-charge soils.

    Science.gov (United States)

    Hyun, Seunghun; Lee, Linda S; Rao, P Suresh C

    2003-01-01

    Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH-and pKa-dependent chemical speciation and using two organic carbon-normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl2, CaSO4, Ca(H2PO4)2 as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl2 and Ca(H2PO4)2 solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides.

  7. Significance of anion exchange in pentachlorophenol sorption by variable-charge soils.

    Science.gov (United States)

    Hyun, Seunghun; Lee, Linda S; Rao, P Suresh C

    2003-01-01

    Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH-and pKa-dependent chemical speciation and using two organic carbon-normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl2, CaSO4, Ca(H2PO4)2 as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl2 and Ca(H2PO4)2 solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides. PMID:12809297

  8. Anion and cation diffusion in barium titanate and strontium titanate

    International Nuclear Information System (INIS)

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO3 single crystals has been studied by means of 18O2/16O2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The data

  9. Bound anions differentially stabilize multiprotein complexes in the absence of bulk solvent.

    Science.gov (United States)

    Han, Linjie; Hyung, Suk-Joon; Mayers, Jonathan J S; Ruotolo, Brandon T

    2011-07-27

    The combination of ion mobility separation with mass spectrometry is an emergent and powerful structural biology tool, capable of simultaneously assessing the structure, topology, dynamics, and composition of large protein assemblies within complex mixtures. An integral part of the ion mobility-mass spectrometry measurement is the ionization of intact multiprotein complexes and their removal from bulk solvent. This process, during which a substantial portion of protein structure and organization is likely to be preserved, imposes a foreign environment on proteins that may cause structural rearrangements to occur. Thus, a general means must be identified to stabilize protein structures in the absence of bulk solvent. Our approach to this problem involves the protection of protein complex structure through the addition of salts in solution prior to desorption/ionization. Anionic components of the added salts bind to the complex either in solution or during the electrospray process, and those that remain bound in the gas phase tend to have high gas phase acidities. The resulting 'shell' of counterions is able to carry away excess energy from the protein complex ion upon activation and can result in significant structural stabilization of the gas-phase protein assembly overall. By using ion mobility-mass spectrometry, we observe both the dissociation and unfolding transitions for four tetrameric protein complexes bound to populations of 12 different anions using collisional activation. The data presented here quantifies, for the first time, the influence of a large range of counterions on gas-phase protein structure and allows us to rank and classify counterions as structure stabilizers in the absence of bulk solvent. Our measurements indicate that tartrate, citrate, chloride, and nitrate anions are among the strongest stabilizers of gas-phase protein structure identified in this screen. The rank order determined by our data is substantially different when compared to

  10. Sensitive fluorescence probes for dihydrogen phosphonate anion based on calix[4]arene bearing naphthol-hydrazone groups

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    t-Butyl and t-pentylcalix[4]arenes bearing two 2-naphthol-1-hydrazone groups at the lower rim were synthesized,and showed excited-state intermolecular proton transfer fluorescent signal with basic anion.They are more sensitive to dihydrogen phosphate anion than to fluoride anion,although the latter has stronger basicity.Compared with t-butylcalix[4]arene bearing two 2-naphthol-1-hydrazone groups,t-pentylcalix[4]arenes derivative has a larger fluorescent difference between dihydrogen phosphate and fluoride anion.This finding may be used to analyze dihydrogen phosphate anion in the presence of fluoride anion and provide a new approach for designing fluorescence probes that are highly selective for H2PO4-.

  11. Off-On-Off fluorescence behavior of an intramolecular charge transfer probe toward anions and CO2.

    Science.gov (United States)

    Ali, Rashid; Razi, Syed S; Shahid, Mohammad; Srivastava, Priyanka; Misra, Arvind

    2016-11-01

    The photophysical behavior of a newly developed fluorescent probe, tricyanoethylphenyl phenanthroimidazole (TCPPI) has been studied. Upon interaction of different class of anions TCPPI displayed naked-eye sensitive fluorescence "turn-on" response to detect selectively F(-) (0.98μM, 18.62ppb) and CN(-) (1.12μM, 29.12ppb) anions in acetonitrile (MeCN). Job's plot analysis revealed a 1:1 binding stoichiometry between probe and anions. The spectral data analysis and 1H NMR titration studies suggested about the affinity of F(-) and CN(-) anions with moderately acidic -NH fragment of imidazolyl unit of probe through deprotonation and H-bonding interaction. Moreover, the anion activated probe upon interaction with CO2 revived photophysical properties of probe, "On-Off-On" type fluorescence and enabled anion-induced CO2 sensing in the medium. PMID:27267280

  12. Off-On-Off fluorescence behavior of an intramolecular charge transfer probe toward anions and CO2

    Science.gov (United States)

    Ali, Rashid; Razi, Syed S.; Shahid, Mohammad; Srivastava, Priyanka; Misra, Arvind

    2016-11-01

    The photophysical behavior of a newly developed fluorescent probe, tricyanoethylphenyl phenanthroimidazole (TCPPI) has been studied. Upon interaction of different class of anions TCPPI displayed naked-eye sensitive fluorescence "turn-on" response to detect selectively F- (0.98 μM, 18.62 ppb) and CN- (1.12 μM, 29.12 ppb) anions in acetonitrile (MeCN). Job's plot analysis revealed a 1:1 binding stoichiometry between probe and anions. The spectral data analysis and 1H NMR titration studies suggested about the affinity of F- and CN- anions with moderately acidic - NH fragment of imidazolyl unit of probe through deprotonation and H-bonding interaction. Moreover, the anion activated probe upon interaction with CO2 revived photophysical properties of probe, "On-Off-On" type fluorescence and enabled anion-induced CO2 sensing in the medium.

  13. Influence of silicate anions structure on desilication in silicate-bearing sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 张闻; 齐天贵; 彭志宏; 周秋生; 李小斌

    2016-01-01

    The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate (solution-SS) is much greater than that in the solution by the addition of green liquor (solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.

  14. Kinetics and mechanism of protection of thymine from sulphate radical anion under anoxic conditions

    Indian Academy of Sciences (India)

    M Sudha Swaraga; M Adinarayana

    2003-04-01

    The rates of photooxidation of thymine in presence of peroxydisulphate (PDS) have been determined by measuring the absorbance of thymine at 264 nm spectrophotometrically. The rates and the quantum yields () of oxidation of thymine by sulphate radical anion have been determined in the presence of different concentrations of caffeic acid. Increase in [caffeic acid] is found to decrease the rate of oxidation of thymine suggesting that caffeic acid acts as an efficient scavenger of SO$^{\\bullet -}_{4}$ and protects thymine from it. Sulphate radical anion competes for thymine as well as for caffeic acid. The rate constant of sulphate radical anion with caffeic acid has been calculated to be 1.24 × 1010 dm3 mol-1 s-1. The quantum yields of photooxidation of thymine have been calculated from the rates of oxidation of thymine and the light intensity absorbed by PDS at 254 nm, the wavelength at which PDS is activated to sulphate radical anion. From the results of experimentally determined quantum yields (exptl) and the quantum yields calculated (cl) assuming caffeic acid acting only as a scavenger of SO$^{\\bullet -}_{4}$ radicals show that exptl values are lower than cl values. The ' values, which are experimentally found quantum yield values at each caffeic acid concentration and corrected for SO$^{\\bullet-}_{4}$ scavenging by caffeic acid, are also found to be greater than exptl values. These observations suggest that the thymine radicals are repaired by caffeic acid in addition to scavenging of sulphate radical anions.

  15. Preparation and chromatographic performance of polymer-based anion exchangers for ion chromatography: A review.

    Science.gov (United States)

    Zatirakha, A V; Smolenkov, A D; Shpigun, O A

    2016-01-21

    In the last decade the developments in the field of ion chromatography (IC) were aimed at increasing the efficiency, sensitivity and rapidity of analysis, as well as on improving separation selectivity. Since selectivity and efficiency to the large extent depend on the surface chemistry of the stationary phase, the development of novel anion exchangers remains one of the priority tasks in modern IC. The exact chemistry of commercially available resins is not known and not many literature data devoted to the procedures of preparing anion exchangers for IC have become available in the last 10-15 years. However, the knowledge about the surface chemistry of anion exchangers can provide understanding of the trends in selectivity and efficiency changes, as well as help with the choice of the stationary phase type suitable for solving a particular analytical task. The current review is devoted to the methods of preparing anion exchangers based on polystyrene-divinylbenzene (PS-DVB) and ethylvinylbenzene-divinylbenzene (EVB-DVB) for IC of inorganic and small organic anions and is aimed at demonstrating the improvement of their performance over the years, which was brought by the development of the new types of stationary phase architecture.

  16. Swelling-Activated Anion Channels Are Essential for Volume Regulation of Mouse Thymocytes

    Directory of Open Access Journals (Sweden)

    Ravshan Z. Sabirov

    2011-12-01

    Full Text Available Channel-mediated trans-membrane chloride movement is a key process in the active cell volume regulation under osmotic stress in most cells. However, thymocytes were hypothesized to regulate their volume by activating a coupled K-Cl cotransport mechanism. Under the patch-clamp, we found that osmotic swelling activates two types of macroscopic anion conductance with different voltage-dependence and pharmacology. At the single-channel level, we identified two types of events: one corresponded to the maxi-anion channel, and the other one had characteristics of the volume-sensitive outwardly rectifying (VSOR chloride channel of intermediate conductance. A VSOR inhibitor, phloretin, significantly suppressed both macroscopic VSOR-type conductance and single-channel activity of intermediate amplitude. The maxi-anion channel activity was largely suppressed by Gd3+ ions but not by phloretin. Surprisingly, [(dihydroindenyloxy] alkanoic acid (DIOA, a known antagonist of K-Cl cotransporter, was found to significantly suppress the activity of the VSOR-type single-channel events with no effect on the maxi-anion channels at 10 μM. The regulatory volume decrease (RVD phase of cellular response to hypotonicity was mildly suppressed by Gd3+ ions and was completely abolished by phloretin suggesting a major impact of the VSOR chloride channel and modulatory role of the maxi-anion channel. The inhibitory effect of DIOA was also strong, and, most likely, it occurred via blocking the VSOR Cl− channels.

  17. A simple ion chromatography method for inorganic anion analysis in edible seaweeds.

    Science.gov (United States)

    Gómez-Ordóñez, Eva; Alonso, Esther; Rupérez, Pilar

    2010-09-15

    A new, simple, fast and sensitive ion chromatography (IC) method, for the simultaneous analysis of fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulphate in edible seaweeds was developed and reported for the first time. The validation of the analytical method was studied in terms of linearity, sensitivity, precision and accuracy. All standard calibration curves showed very good correlation between anion peak area and concentration (r>0.999). Limits of detection and quantitation ranged between 0.002-0.05 mg/L and 0.01-0.1mg/L, respectively and indicated the high sensitivity of the method. Relative standard deviation values of repeatability and inter-day precision for standard anions with the same sample were less than 2%. Anion recoveries ranged from 97 to 113% for chloride and from 87 to 105% for sulphate, respectively and showed the fairly good accuracy of the method. The method was applied to the analysis of inorganic anions in brown and red edible seaweeds. Brown seaweeds were characterized by higher chloride content up to 33.7-36.9%, while red seaweeds were characterized by higher sulphate content (45-57%). Sulphate content in seaweeds is related to the presence of sulphated polysaccharides of biological importance. The method developed was well applicable to mineral anion analysis in edible seaweeds and shows suitability and reliability of use in other food samples of nutritional importance. PMID:20801334

  18. Rigid-rod anion-pi slides for multiion hopping across lipid bilayers.

    Science.gov (United States)

    Gorteau, Virginie; Bollot, Guillaume; Mareda, Jiri; Matile, Stefan

    2007-09-21

    Shape-persistent oligo-p-phenylene-N,N-naphthalenediimide (O-NDI) rods are introduced as anion-pi slides for chloride-selective multiion hopping across lipid bilayers. Results from end-group engineering and covalent capture as O-NDI hairpins suggested that self-assembly into transmembrane O-NDI bundles is essential for activity. A halide topology VI (Cl > F > Br approximately I, Cl/Br approximately Cl/I > 7) implied strong anion binding along the anion-pi slides with relatively weak contributions from size exclusion (F >or= OAc). Anomalous mole fraction effects (AMFE) supported the occurrence of multiion hopping along the pi-acidic O-NDI rods. The existence of anion-pi interactions was corroborated by high-level ab initio and DFT calculations. The latter revealed positive NDI quadrupole moments far beyond the hexafluorobenzene standard. Computational studies further suggested that anion binding occurs at the confined, pi-acidic edges of the sticky NDI surface and is influenced by the nature of the phenyl spacer between two NDIs. With regard to methods development, a detailed analysis of the detection of ion selectivity with the HPTS assay including AMFE in vesicles is provided. PMID:17728867

  19. Fluoride adsorption onto amorphous aluminum hydroxide: Roles of the surface acetate anions.

    Science.gov (United States)

    Zhang, Yong-Xing; Jia, Yong

    2016-12-01

    Amorphous aluminum hydroxide with hydroxyl groups, acetate anions and chlorine anions enriched surface was synthesized, and was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. Batch experiments were performed to study the influence of various experimental parameters such as contact time, initial fluoride concentration, temperature, pH value and the presence of competing anions on the adsorption of fluoride on amorphous aluminum hydroxide. The kinetic data was well fitted to pseudo-second-order model. The fluoride adsorption on the amorphous aluminum hydroxide can be well described by the Langmuir model, and the maximum adsorption capacity was 63.94mgg(-1) at pH 7.0. Thermodynamic parameters including the Gibbs free energy, standard enthalpy and standard entropy were calculated, and the results suggested that the adsorption of fluoride on the amorphous aluminum hydroxide was a feasible, spontaneous and exothermic process. The adsorption mechanism was revealed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis. The results suggested that the surface acetate anions and surface chlorine anions played important roles in the fluoride removal process. PMID:27565961

  20. Formation of Carbamate Anions by the Gas-phase Reaction of Anilide Ions with CO2

    Science.gov (United States)

    Liu, Chongming; Nishshanka, Upul; Attygalle, Athula B.

    2016-05-01

    The anilide anion ( m/z 92) generated directly from aniline, or indirectly as a fragmentation product of deprotonated acetanilide, captures CO2 readily to form the carbamate anion ( m/z 136) in the collision cell, when CO2 is used as the collision gas in a tandem-quadrupole mass spectrometer. The gas-phase affinity of the anilide ion to CO2 is significantly higher than that of the phenoxide anion ( m/z 93), which adds to CO2 only very sluggishly. Our results suggest that the efficacy of CO2 capture depends on the natural charge density on the nitrogen atom, and relative nucleophilicity of the anilide anion. Generally, conjugate bases generated from aniline derivatives with proton affinities (PA) less than 350 kcal/mol do not tend to add CO2 to form gaseous carbamate ions. For example, the anion generated from p-methoxyaniline (PA = 367 kcal/mol) reacts significantly faster than that obtained from p-nitroaniline (PA = 343 kcal/mol). Although deprotonated p-aminobenzoic acid adds very poorly because the negative charge is now located primarily on the carboxylate group, it reacts more efficiently with CO2 if the carboxyl group is esterified. Moreover, mixture of CO2 and He as the collision gas was found to afford more efficient adduct formation than CO2 alone, or as mixtures made with nitrogen or argon, because helium acts as an effective "cooling" gas and reduces the internal energy of reactant ions.

  1. Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

    Directory of Open Access Journals (Sweden)

    Lin-Tong Yang

    2013-01-01

    Full Text Available Approximately 30% of the world’s total land area and over 50% of the world’s potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a anion channels or transporters, (b internal concentrations of OA anions in plant tissues, (d temperature, (e root plasma membrane (PM H+-ATPase, (f magnesium (Mg, and (e phosphorus (P. Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.

  2. Roles of organic acid anion secretion in aluminium tolerance of higher plants.

    Science.gov (United States)

    Yang, Lin-Tong; Qi, Yi-Ping; Jiang, Huan-Xin; Chen, Li-Song

    2013-01-01

    Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium (Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H(+)-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed.

  3. A Study on the Structure and Photodetachment Dynamics of Copper Based Molecular Anions Using Photoelectron Spectroscopy

    Science.gov (United States)

    Holtgrewe, Nicholas Stephen

    This dissertation represents a study of the effects of electron molecule interactions in the detachment and dissociation dynamics of copper based molecular anions. Results are presented on the photodetachment of small copper oxide CuOn-- (n = 1, 2) and copper fluoride CuFn-- (n = 1, 2) molecular anions. Effects of different resonances are explored using the photoelectron angular distributions (PADs) and the relative intensity variations in vibrational channel cross sections. The specific resonances studied include dipole bound resonances, in which the electric dipole moment of the neutral molecule captures the outgoing electron, and electronic Feshbach resonances, in which the anion undergoes absorption to an excited anion state (lying energetically above the neutral) followed by relaxation via autodetachment into the electronic continuum. In addition to electron scattering resonances, the effects of dissociation dynamics on linear CuO2-- are studied, wherein the linear anion isomer was found to dissociate to Cu-- fragments. This dissociation process is interpreted with experimental data acquired from nanosecond photoelectron images and a femtosecond time resolved study.

  4. Conformational preference of 'CαNN' short peptide motif towards recognition of anions.

    Directory of Open Access Journals (Sweden)

    Tridip Sheet

    Full Text Available Among several 'anion binding motifs', the recently described 'C(αNN' motif occurring in the loop regions preceding a helix, is conserved through evolution both in sequence and its conformation. To establish the significance of the conserved sequence and their intrinsic affinity for anions, a series of peptides containing the naturally occurring 'C(αNN' motif at the N-terminus of a designed helix, have been modeled and studied in a context free system using computational techniques. Appearance of a single interacting site with negative binding free-energy for both the sulfate and phosphate ions, as evidenced in docking experiments, establishes that the 'C(αNN' segment has an intrinsic affinity for anions. Molecular Dynamics (MD simulation studies reveal that interaction with anion triggers a conformational switch from non-helical to helical state at the 'C(αNN' segment, which extends the length of the anchoring-helix by one turn at the N-terminus. Computational experiments substantiate the significance of sequence/structural context and justify the conserved nature of the 'C(αNN' sequence for anion recognition through "local" interaction.

  5. The effects of cations and anions on hydrogen chemisorption at Pt

    Science.gov (United States)

    Huang, J. C.; Ogrady, W. E.; Yeager, E.

    1977-01-01

    Experimental evidence based on linear sweep voltammetry is presented to substantiate the view that ionic adsorption substantially shifts electrode potentials in addition to the relative heights of the hydrogen adsorption peaks. HClO4 and HF are chosen as better reference electrolytes for anion studies. The voltammetry curves for 0.1M HF and 0.1M HClO4 as well as the effect of adding successively increasing amounts of H2SO4 to these electrolytes are discussed. The measurements are also extended to alkaline solutions. Mechanisms whereby the addition of various cations and anions to electrolytes such as HF and HClO4 can induce changes in the structure of the hydrogen adsorption region in the voltammetry curves are identified: (1) blocking of sites by anion adsorption and coupling of hydrogen adsorption and anion desorption, (2) modification in the hydrogen adsorption energies for sites adjacent to adsorbed anions, (3) changes in the potential distribution across the interface, and (4) surface restructuring.

  6. NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas

    Directory of Open Access Journals (Sweden)

    Janez Plavec

    2011-09-01

    Full Text Available The conformational properties of 1,3-diindolylureas and thioureas were studied by a combination of heteronuclear NMR spectroscopy and quantum mechanics calculations. NOE experiments showed that the anti–anti conformer along the C7–N7α bonds was predominant in DMSO-d6 solution in the absence of anions. Anion-induced changes in the 1H and 15N chemical shifts confirm the weak binding of chloride anions with negligible conformational changes. Strong deshielding of ureido protons and moderate deshielding of indole NH was observed upon the addition of acetate, benzoate, bicarbonate and dihydrogen phosphate, which indicated that the predominant hydrogen bond interactions occurred at the urea donor groups. Binding of oxo-anions caused conformational changes along the C7–N7α bonds and the syn–syn conformer was preferred for anion–receptor complexes. The conformational changes upon anion binding are in good agreement with energetic preferences established by ab initio calculations.

  7. ON THE UBIQUITY OF MOLECULAR ANIONS IN THE DENSE INTERSTELLAR MEDIUM

    International Nuclear Information System (INIS)

    Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H– is detected in all seven target sources, including four sources where no anions have been previously detected: L1172, L1389, L1495B, and TMC-1C. The C6H–/C6H column density ratio is ∼> 1.0% in every source, with a mean value of 3.0% (and standard deviation 0.92%). Combined with previous detections, our results show that anions are ubiquitous in dense clouds wherever C6H is present. The C6H–/C6H ratio is found to show a positive correlation with molecular hydrogen number density, and with the apparent age of the cloud. We also report the first detection of C4H– in TMC-1 (at 4.8σ confidence), and derive an anion-to-neutral ratio C4H–/C4H =(1.2 ± 0.4) × 10–5(= 0.0012% ± 0.0004%). Such a low value compared with C6H– highlights the need for a revised radiative electron attachment rate for C4H. Chemical model calculations show that the observed C4H– could be produced as a result of reactions of oxygen atoms with C5H– and C6H–.

  8. Study on Synthesis and Binding Ability of a New Anion Receptor Containing NH Binding Sites

    Institute of Scientific and Technical Information of China (English)

    QIAO,Yan-Hong; LIN,Hai; LIN,Hua-Kuan

    2007-01-01

    A new colorimetric recognition receptor 1 based on the dual capability containing NH binding sites of selectively sensing anionic guest species has been synthesized. Compared with other halide anions, its UV/Vis absorption spectrum in dimethyl sulfoxide showed the response toward the presence of fluoride anion with high selectivity,and also displayed dramatic color changes from colorless to yellow in the presence of TBAF (5 × 10-5 mol/L). The similar UV/Vis absorption spectrum change also occurred when 1 was treated with AcO- while a little change with H2PO-4 and OH-. Receptor 1 has almost not affinity abilities to Cl-, Br- and I-. The binding ability of receptor 1to fluoride with high selectivity over other halides contributes to the anion size and the ability of forming hydrogen bonding. While the different ability of binding with geometrically triangular (AcO-), tetrahedral (H2PO-4 ) and linear (OH-) anions maybe result from their geometry configuration.

  9. Kinetic evidence for an anion binding pocket in the active site of nitronate monooxygenase.

    Science.gov (United States)

    Francis, Kevin; Gadda, Giovanni

    2009-10-01

    A series of monovalent, inorganic anions and aliphatic aldehydes were tested as inhibitors for Hansenula mrakii and Neurospora crassa nitronate monooxygenase, formerly known as 2-nitropropane dioxygenase, to investigate the structural features that contribute to the binding of the anionic nitronate substrates to the enzymes. A linear correlation between the volumes of the inorganic anions and their effectiveness as competitive inhibitors of the enzymes was observed in a plot of pK(is)versus the ionic volume of the anion with slopes of 0.041+/-0.001 mM/A(3) and 0.027+/-0.001 mM/A(3) for the H. mrakii and N. crassa enzymes, respectively. Aliphatic aldehydes were weak competitive inhibitors of the enzymes, with inhibition constants that are independent of their alkyl chain lengths. The reductive half reactions of H. mrakii nitronate monooxygenase with primary nitronates containing two to four carbon atoms all showed apparent K(d) values of approximately 5 mM. These results are consistent with the presence of an anion binding pocket in the active site of nitronate monooxygenase that interacts with the nitro group of the substrate, and suggest a minimal contribution of the hydrocarbon chain of the nitronates to the binding of the ligands to the enzyme. PMID:19683782

  10. Refeeding syndrome as an unusual cause of anion gap metabolic acidosis.

    Science.gov (United States)

    Singla, Manish; Perry, Alexandra; Lavery, Eric

    2012-11-01

    Refeeding syndrome is characterized by hypophosphatemia in the setting of malnutrition. It is commonly seen in patients with anorexia, alcoholism, or malignancy, and it is often a missed diagnosis. Because of the potential morbidity associated with missing the diagnosis of refeeding syndrome, it is important to monitor for this disease in any malnourished patient. We present a case of a 49-year-old male with chronic alcohol abuse who presented for alcohol detoxification and was found to have low phosphate, potassium, and magnesium on presentation, in addition to an elevated anion gap of unclear etiology. After extensive workup to evaluate the cause of his elevated anion gap and worsening of his electrolyte abnormalities despite replenishment, it was felt his symptoms were a result of refeeding syndrome. After oral intake was held and aggressive electrolyte replenishment was performed for 24 hours, the patient's anion gap closed and his electrolyte levels stabilized. This case demonstrates a unique presentation of refeeding syndrome given the patient's profound metabolic acidosis that provided a clue toward his eventual diagnosis. The standard workup for an anion gap metabolic acidosis was negative, and it was not until his refeeding syndrome had been treated that the anion gap closed.

  11. On the ubiquity of molecular anions in the dense interstellar medium

    CERN Document Server

    Cordiner, M A; Wirström, E S; Olofsson, A O H; Charnley, S B

    2013-01-01

    Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H- is detected in all seven target sources, including four sources where no anions have been previously detected: L1172, L1389, L1495B and TMC-1C. The C6H-/C6H column density ratio is greater than about 1.0% in every source, with a mean value of 3.0% (and standard deviation 0.92%). Combined with previous detections, our results show that anions are ubiquitous in dense clouds wherever C6H is present. The C6H-/C6H ratio is found to show a positive correlation with molecular hydrogen number density, and with the apparent age of the cloud. We also report the first detection of C4H- in TMC-1 (at 4.8-sigma confidence), and derive an anion-to-neutral ratio C4H-/C4H = (1.2 +- 0.4) x 10^-5 (= 0.0012 +- 0.0004%). Such a low value compared with C6H- highlights the need for a revised radiative electron attachment rate for C4H. Chemical model calculations show that the observed...

  12. Anion Complexes with Tetrazine-Based Ligands: Formation of Strong Anion-π Interactions in Solution and in the Solid State.

    Science.gov (United States)

    Savastano, Matteo; Bazzicalupi, Carla; Giorgi, Claudia; García-Gallarín, Celeste; López de la Torre, Maria Dolores; Pichierri, Fabio; Bianchi, Antonio; Melguizo, Manuel

    2016-08-15

    Ligands L1 and L2, consisting of a tetrazine ring decorated with two morpholine pendants of different lengths, show peculiar anion-binding behaviors. In several cases, even the neutral ligands, in addition to their protonated HL(+) and H2L(2+) (L = L1 and L2) forms, bind anions such as F(-), NO3(-), PF6(-), ClO4(-), and SO4(2-) to form stable complexes in water. The crystal structures of H2L1(PF6)2·2H2O, H2L1(ClO4)2·2H2O, H2L2(NO3)2, H2L2(PF6)2·H2O, and H2L2(ClO4)2·H2O show that anion-π interactions are pivotal for the formation of these complexes, although other weak forces may contribute to their stability. Complex stability constants were determined by means of potentiometric titration in aqueous solution at 298.1 K, while dissection of the free-energy change of association (ΔG°) into its enthalpic (ΔH°) and entropic (TΔS°) components was accomplished by means of isothermal titration calorimetry measurements. Stability constants are poorly regulated by anion-ligand charge-charge attraction. Thermodynamic data show that the formation of complexes with neutral ligands, which are principally stabilized by anion-π interactions, is enthalpically favorable (-ΔG°, 11.1-17.5 kJ/mol; ΔH°, -2.3 to -0.5 kJ/mol; TΔS°, 9.0-17.0 kJ/mol), while for charged ligands, enthalpy changes are mostly unfavorable. Complexation reactions are invariably promoted by large and favorable entropic contributions. The importance of desolvation phenomena manifested by such thermodynamic data was confirmed by the hydrodynamic results obtained by means of diffusion NMR spectroscopy. In the case of L2, complexation equilibria were also studied in a 80:20 (v/v) water/ethanol mixture. In this mixed solvent of lower dielectric constant than water, the stability of anion complexes decreases, relative to water. Solvation effects, mostly involving the ligand, are thought to be responsible for this peculiar behavior.

  13. Novel heterocyclic thiosemicarbazones derivatives as colorimetric and "turn on" fluorescent sensors for fluoride anion sensing employing hydrogen bonding.

    Science.gov (United States)

    Ashok Kumar, S L; Saravana Kumar, M; Sreeja, P B; Sreekanth, A

    2013-09-01

    Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques. PMID:23714188

  14. Nanostructured polymers with high surface area using inorganic templates for the efficient extraction of anionic dyes from solutions.

    Science.gov (United States)

    Zhang, Tao; Huang, Xiaoxi; Asefa, Tewodros

    2015-11-18

    A protonated polyaniline-functionalized SBA-15 mesoporous silica nanomaterial (H(+)-PANI/SBA-15) with high surface area and ideal surface properties for the adsorption of anionic dyes is synthesized. Compared with the conventional emeraldine salt of polyaniline (H(+)-PANI), H(+)-PANI/SBA-15 has a significantly higher adsorption capacity for the anionic dye Orange G and is a more effective sorbent for the removal of anionic pollutants from wastewater. PMID:26391100

  15. Models for the estimation of thermodynamic properties of layered double hydroxides: application to the study of their anion exchange characteristics

    Directory of Open Access Journals (Sweden)

    Bravo-Suárez Juan J.

    2004-01-01

    Full Text Available Several models for the estimation of thermodynamic properties of layered double hydroxides (LDHs are presented. The predicted thermodynamic quantities calculated by the proposed models agree with experimental thermodynamic data. A thermodynamic study of the anion exchange process on LDHs is also made using the described models. Tables for the prediction of monovalent anion exchange selectivities on LDHs are provided. Reasonable agreement is found between the predicted and the experimental monovalent anion exchange selectivities.

  16. Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

    Science.gov (United States)

    Huang, Zhongping; Ni, Chengzhu; Zhu, Zhuyi; Pan, Zaifa; Wang, Lili; Zhu, Yan

    2015-05-01

    The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ≥ 0.9990. The limits of detection were in the range of 0.67 to 1.51 μg/L, based on the signal-to-noise ratio of 3 and a 25 μL injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts.

  17. CH-directed anion-pi interactions in the crystals of pentafluorobenzyl-substituted ammonium and pyridinium salts.

    Science.gov (United States)

    Albrecht, Markus; Müller, Michael; Mergel, Olga; Rissanen, Kari; Valkonen, Arto

    2010-05-01

    Simple pentafluorobenzyl-substituted ammonium and pyridinium salts with different anions can be easily obtained by treatment of the parent amine or pyridine with the respective pentafluorobenzyl halide. Hexafluorophosphate is introduced as the anion by salt metathesis. In the case of the ammonium salt 4, water co-crystallisation seems to suppress effective anion-pi interactions of bromide with the electron-deficient aromatic system, whereas with salts 5 and 6 such interactions are observed despite the presence of water. However, due to asymmetric hydrogen-bonding interactions with ammonium side chains, the anion of 5 is located close to the rim of the pentafluorophenyl group (eta(1) interaction). In 6 the CH-anion hydrogen bonding is more symmetric and fixes the anion on top of the ring (eta(6)). A similar structure-controlling effect is observed in case of the 1,4-diazabicyclo[2.2.2]octane derivatives 7. Here the position of the anion (Cl, Br, I) is shifted according to the length of the weak CH-halide interaction. The hexafluorophosphate 7 d reveals that this "non-coordinating" anion can be located on top of an aromatic pi system. In the methyl-substituted pyridinium salts 9 and 10 different locations of the bromide anions with respect to the pi system are observed. This is due to different conformations of the mono- versus disubstituted pyridine, which leads to different directions of the weak, but structurally important, H(Me)-Br bonds. PMID:20349467

  18. Quantum Mechanics of Insitu Synthesis of Inorganic Nanoparticles with in Anionic Microgels

    CERN Document Server

    Baig, Mirza Wasif

    2013-01-01

    In this work, we discuss the quantum mechanics of many-body systems i.e. hybrid microgel consisting of negatively charged anionic microgels possessing thick sheath of water molecules solvating its protruding anionic moieties and nanoparticle captivated with in it. Thermodynamic feasibility of synthesis of particular nanoparticle with in the microgel is dependent upon the magnitude of interaction between nanoparticle, water molecules and microgel relative to sum of magnitude of self-interaction between counterions and interaction between counterions and microgel. Nanoparticles synthesized with in the microgels have thick electronic cloud that oscillates under the influence of net interaction potential of charged anionic moieties and solvent water molecules. Hamiltonian describing energy of oscillating electronic cloud wrapped around nanoparticle is mathematically derived to be equal to product of integral of electron density and its position vector overall space multiplied with net electric force acting on the...

  19. Electrochemical and Spectroscopic Study on the Interaction of Cytochrome c with Anionic Lipid Vesicles

    Institute of Scientific and Technical Information of China (English)

    JING,Wei-Guo; LIU,Chang-Wei; TANG,Ji-Lin; WU,Zheng-Yan; DONG,Shao-Jun; WANG,Er-kang

    2003-01-01

    The structure and the electron-transfer of cytochrome c binding on the anionic lipid vesicles wrer analyzed by electrochemical and various spectroscopic methods.It was found that upon binding to anionic lipid membrane,the formal potential of cytochrome c shifted 30 mV negtively indicating an easier redox interaction than that in its native state.This is due to the local alteration of the coordination and the heme crevice.The structural perturbation in which a molten globule-like state is formed during binding to anionic lipid vesicles is more important.This study may help to understand the mechanism of the electron-transfer reactions of cytochrome c at the mitochondrial membrane.

  20. Utility of anion and cation combinations for phasing of protein structures.

    Science.gov (United States)

    Sharma, Ashwani; Yogavel, Manickam; Sharma, Amit

    2012-09-01

    We report the use of anionic (I(-)), cationic (Ba(2+), Cd(2+)) and ionic mixtures (I(-) plus Ba(2+)) for derivatizing liver fatty acid binding protein (LFABP) crystals. Use of cationic and anionic salts in phasing experiments revealed distinct non-overlapping sites for these ions, suggesting exclusive binding regions on LFABP. Interestingly, cations of identical charge and valency (like Ba(2+) and Cd(2+)) bound to distinct pockets on the protein surface. Furthermore, a mixture of salts containing both I(-) and Ba(2+) was very useful in phasing experiments as these oppositely charged ions bound to different regions of LFABP. Our data therefore suggest that cationic and anionic salt mixtures like BaCl(2) with NH(4)I or salts like CdI, BaI where each ion has a significant anomalous signal for a given X-ray wavelength may be valuable reagents for phasing during structure determination. PMID:22562242

  1. Ionic liquid based lithium battery electrolytes: fundamental benefits of utilising both TFSI and FSI anions?

    Science.gov (United States)

    Kerner, M; Plylahan, N; Scheers, J; Johansson, P

    2015-07-15

    Several IL based electrolytes with an imidazolium cation (EMI) have been investigated trying to elucidate a possible beneficial effect of mixing FSI and TFSI anions in terms of physico-chemical properties and especially Li(+) solvation. All electrolytes were evaluated in terms of phase transitions, densities and viscosities, thermal stabilities, ionic conductivities and local structure, i.e. charge carriers. The electrolytes with up to 20% of Li-salts showed to be promising for high temperature lithium ion battery application (ca. 100 °C) and a synergetic effect of having mixed anions is discernible with the LiTFSI0.2EMIFSI0.8 electrolyte giving the best overall performance. The determination of the charge carriers revealed the SN to be ca. 2 for all analysed electrolytes, and proved the analysis of the mixed anion electrolytes to be challenging and inherently leads to an ambiguous picture of the Li(+) solvation. PMID:26147418

  2. Separation of metal ions by anion exchange in mixtures of hydrochloric acid and hydrofluoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Faris, J.P.

    1978-12-01

    Distribution coefficients were determined for the adsorption of more than 40 elements on anion-exchange resins from mixtures of HCl (0.1 to 12M) and HF (0.1-8M). Two resins, Dowex 1 x 10, 200 to 400 mesh and Dowex 1 x 4, 100 to 200 mesh, were used. Distribution coefficients were also determined for the adsorption of many elements on both resins from 0.1 to 12M HCl and 0.1 to 12M HF. Anion exchange in the presence of HF was found useful for separating impurities from various materials for their subsequent determination, and specific procedures used in our spectrochemical laboratory for this purpose are outlined. The results of a literature search on the use of anion exchange in hydrofluoric acid and fluoride-containing media are presented in an extensive bibliography. 404 references, 9 tables.

  3. New type of sorbents based on polyethers and some hydrophobic anions Part 1

    International Nuclear Information System (INIS)

    New type of sorbent, based on the complexing properties of polyethyleneglycols, with high selectivity for Ba and Sr is described. The dependences of Ksub(d) on the initial concentration of HNO3 for Ba, Sr, Eu, Ce, Cs and Na were studied. The capacity of two model sorbents for uptake of Cs and Sr is given. The properties of the sorbents are compared with those of the ammonium salts of heteropolyacids. The precipitation reaction of the protonised form of polyethyleneglycol with anions of heteropolyacids yields a new type of sorbent which behaviour is largely modified in comparison with ammonium salts of heteropolyacids. The affinity and selectivity towards alakalalkaline earth cations is rather determined by the properties of the polyethyleneglycol than those of the heteropolyacid anion, whereas the sorption capacity is apparently given by the kind of the anion used and its the same as for the respective ammonium salt. (T.G.)

  4. Removal of Anionic Metal Ions from Wastewater by Hydroxide-type Adsorbents

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Generally speaking, anionic metal concentrations in wastewater from industries and mineral processing plants are well above the allowed limits for effluent set by the Ministry of Environment of Japan. Nowadays, the removal of anionic ions has been considered difficult and development of new process is desperately needed. In this paper, we report the development of three hydroxide-type adsorbents, illustrating their adsorption efficiency in removing As, Se, Mo and Sb ions from aqueous solutions. The main finding of this work was that the adsorption behavior was influenced very much by both the pH and the adsorbent concentration. Nevertheless, the newly developed hydroxide-type adsorbents were very effective in reducing the concentration of those anionic ions.

  5. Solvation of the fluorine containing anions and their lithium salts in propylene carbonate and dimethoxyethane.

    Science.gov (United States)

    Chaban, Vitaly

    2015-07-01

    Electrolyte solutions based on the propylene carbonate (PC)-dimethoxyethane (DME) mixtures are of significant importance and urgency due to emergence of lithium-ion batteries. Solvation and coordination of the lithium cation in these systems have been recently attended in detail. However, analogous information concerning anions (tetrafluoroborate, hexafluorophosphate) is still missed. This work reports PM7-MD simulations (electronic-structure level of description) to include finite-temperature effects on the anion solvation regularities in the PC-DME mixture. The reported result evidences that the anions appear weakly solvated. This observation is linked to the absence of suitable coordination sites in the solvent molecules. In the concentrated electrolyte solutions, both BF4(-) and PF6(-) prefer to exist as neutral ion pairs (LiBF4, LiPF6). PMID:26067106

  6. Infrared diode laser study of the hydrogen bifluoride anion FHF(-) and FDF(-)

    Science.gov (United States)

    Kawaguchi, K.; Hirota, E.

    1986-03-01

    In connection with certain difficulties, no infrared spectroscopic studies of anions in discharge plasmas have been reported until the recent observations of the OH(-) vibration-rotation spectrum by Owrutsky et al. (1985). The present paper is concerned with observations regarding the vibration-rotation spectrum of the hydrogen bifluoride anion. The FHF(-) ion has played an important part in the study of the hydrogen bond. The high-resolution infrared study reported in this paper gives precise information about the molecular structure and vibrational frequencies of the anion. It is pointed out that the frequency shift between the gas phase and the solid phase, especially observed in the nu-3 band, will be useful to estimate intermolecular forces in the solid phase. Attention is given to the experiments, the observed spectra and the analysis, the velocity modulated spectrum and identification of molecular species, the vibrational assignments for FHF(-), and the spectrum of FDF(-).

  7. Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Study on nanomaterials has attracted great interests in recent years. In this article,zirconia nanocrystallites of different structures have been successfully synthesized via hydrothermal methods with cationic surfactant (CTAB) and anionic surfactant (SDS), respectively. Differential Scanning Calorimeter (DSC-TG), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Ultraviolet-Visible (UV-vis) and N2 adsorption-desorption analyses are used for their structure characteristics. The results show that the cationic surfactant has a distinctive direction effect on the formation of zirconia nanocrystallites, while the anionic surfactant has a self-assembly synergistic effect on them. The sample synthesized with the cationic surfactant presents good dispersion with the main phase of tetragonal zirconia, and the average nanocryst al size is around 15nm after calcination at 500 ℃. While the sample synthesized with the anionic surfactant exhibits a worm-like mesoporous structure with pure tetragonal phase after calcination at 500 ℃ and with good thermal stability.

  8. Asymmetric Anion-π Catalysis: Enamine Addition to Nitroolefins on π-Acidic Surfaces.

    Science.gov (United States)

    Zhao, Yingjie; Cotelle, Yoann; Avestro, Alyssa-Jennifer; Sakai, Naomi; Matile, Stefan

    2015-09-16

    Here we provide experimental evidence for anion-π catalysis of enamine chemistry and for asymmetric anion-π catalysis. A proline for enamine formation on one side and a glutamic acid for nitronate protonation on the other side are placed to make the enamine addition to nitroolefins occur on the aromatic surface of π-acidic naphthalenediimides. With increasing π acidity of the formally trifunctional catalysts, rate and enantioselectivity of the reaction increase. Mismatched and more flexible controls reveal that the importance of rigidified, precisely sculpted architectures increases with increasing π acidity as well. The absolute configuration of stereogenic sulfoxide acceptors at the edge of the π-acidic surface has a profound influence on asymmetric anion-π catalysis and, if perfectly matched, affords the highest enantio- and diastereoselectivity.

  9. Piezoelectric two-dimensional nanosheets/anionic layer heterojunction for efficient direct current power generation

    Science.gov (United States)

    Kim, Kwon-Ho; Kumar, Brijesh; Lee, Keun Young; Park, Hyun-Kyu; Lee, Ju-Hyuck; Lee, Hyun Hwi; Jun, Hoin; Lee, Dongyun; Kim, Sang-Woo

    2013-06-01

    Direct current (DC) piezoelectric power generator is promising for the miniaturization of a power package and self-powering of nanorobots and body-implanted devices. Hence, we report the first use of two-dimensional (2D) zinc oxide (ZnO) nanostructure and an anionic nanoclay layer to generate piezoelectric DC output power. The device, made from 2D nanosheets and an anionic nanoclay layer heterojunction, has potential to be the smallest size power package, and could be used to charge wireless nano/micro scale systems without the use of rectifier circuits to convert alternating current into DC to store the generated power. The combined effect of buckling behaviour of the ZnO nanosheets, a self-formed anionic nanoclay layer, and coupled semiconducting and piezoelectric properties of ZnO nanosheets contributes to efficient DC power generation. The networked ZnO nanosheets proved to be structurally stable under huge external mechanical loads.

  10. Investigation of hybrid molecular material prepared by ionic liquid and polyoxometalate anion

    Indian Academy of Sciences (India)

    T Rajkumar; G Ranga Rao

    2008-11-01

    A solid hybrid molecular material containing 1-butyl 3-methyl imidazolium cations and Keggin anions of phosphotungstic acid has been synthesized. It is fully characterized by CHN analysis, FTIR, XRD, UV-Vis-NIR DRS, 31P MAS NMR, TGA and SEM. The FTIR spectrum of the compound shows the fingerprint vibrational bands of both Keggin molecular anions and imidazolium cations. The aromatic C-H stretch region (2700-3250 cm-1) of imidazolium cation is split due to the interaction between the ring C-H and bulky Keggin anion. The red-shift in the UV-Vis spectra and the downfield 31P MAS NMR chemical shift also confirm the electrostatic interaction between the ions in the compound. Near IR spectral region (1000-2500 nm) shows the elimination of water in the compound which is hydrophobic.

  11. Anion Sensing Properties of New Colorimetric Chemosensors Based on Thiourea and Urea Moieties

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Wan; Kim, Jung Hwan; Hwang, Jae Young; Park, Jong Keun; Kim, Jae Sang [Gyeongsang National University, Jinju (Korea, Republic of)

    2012-04-15

    A new colorimetric sensors containing thiourea (1-(4-nitrophenyl)-3-quinolin-6-ylthiourea: 1) and urea(1-(4- nitrophenyl)-3-quinolin-6-ylurea: 2) moieties for fluoride were designed and synthesized. These simple receptors were characterized their stoichiometry, and investigates the mechanism of their selectivity as anion receptors. The addition of tetrabutylammonium fluoride salts to the solution of receptors caused a dramatically and clearly observable color changes from colorless to yellow. To examine their application as anion receptors by UV-vis and {sup 1}H NMR spectroscopy results revealed their higher selectivity for fluoride ion than other anions. The receptors and fluoride ion formed a 1:1 stoichiometry complex through strong hydrogen bonding interactions in the first step, followed by a process of deprotonation in presence of an excess of F{sup -} in DMSO solvent

  12. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    Directory of Open Access Journals (Sweden)

    Johannes Ranke

    2009-03-01

    Full Text Available The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

  13. Piezoelectric two-dimensional nanosheets/anionic layer heterojunction for efficient direct current power generation.

    Science.gov (United States)

    Kim, Kwon-Ho; Kumar, Brijesh; Lee, Keun Young; Park, Hyun-Kyu; Lee, Ju-Hyuck; Lee, Hyun Hwi; Jun, Hoin; Lee, Dongyun; Kim, Sang-Woo

    2013-01-01

    Direct current (DC) piezoelectric power generator is promising for the miniaturization of a power package and self-powering of nanorobots and body-implanted devices. Hence, we report the first use of two-dimensional (2D) zinc oxide (ZnO) nanostructure and an anionic nanoclay layer to generate piezoelectric DC output power. The device, made from 2D nanosheets and an anionic nanoclay layer heterojunction, has potential to be the smallest size power package, and could be used to charge wireless nano/micro scale systems without the use of rectifier circuits to convert alternating current into DC to store the generated power. The combined effect of buckling behaviour of the ZnO nanosheets, a self-formed anionic nanoclay layer, and coupled semiconducting and piezoelectric properties of ZnO nanosheets contributes to efficient DC power generation. The networked ZnO nanosheets proved to be structurally stable under huge external mechanical loads.

  14. Anion-exchange Studies of Radioactive Trace Elements in Sulphuric Acid Solutions

    International Nuclear Information System (INIS)

    As part of a chemical group separation procedure used as a pretreatment in gamma spectrometric analysis, a study has been made of the adsorption from sulphuric acid solutions on strongly basic anion exchange resins, prepared in the hydroxide and the sulphate forms, of trace activities of Na, P, K, Ca, Sc, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Nb, Mo, Tc, Ag, Cd, In, Cs, Ba, La, Ce, Hf, Ta, W, Ir, Pa and Np. Besides adsorbing some of the trace elements in the solution, the anion exchange resin in the hydroxide form will neutralize the bulk of the sulphuric acid. This makes possible the subsequent sequential separation of chloride complexes on short anion-exchange columns by a stepwise increasing of the HCl concentration of the solution. On the basis of the results obtained in the present and earlier experiments, a new improved chemical group-separation procedure for mixtures of radioactive trace elements is outlined

  15. Solvation of monovalent anions in formamide and methanol: Parameterization of the IEF-PCM model

    International Nuclear Information System (INIS)

    The thermodynamics of solvation for a series of monovalent anions in formamide and methanol has been studied using the polarizable continuum model (PCM). The parameterization of this continuum model was guided by molecular dynamics simulations. The parameterized PCM model predicts the Gibbs free energies of solvation for 13 anions in formamide and 16 anions in methanol in very good agreement with experimental data. Two sets of atomic radii were tested in the definition of the solute cavities in the PCM and their performances are evaluated and discussed. Mean absolute deviations of the calculated free energies of solvation from the experimental values are in the range of 1.3-2.1 kcal/mol

  16. NEUROSCIENCE. Natural light-gated anion channels: A family of microbial rhodopsins for advanced optogenetics.

    Science.gov (United States)

    Govorunova, Elena G; Sineshchekov, Oleg A; Janz, Roger; Liu, Xiaoqin; Spudich, John L

    2015-08-01

    Light-gated rhodopsin cation channels from chlorophyte algae have transformed neuroscience research through their use as membrane-depolarizing optogenetic tools for targeted photoactivation of neuron firing. Photosuppression of neuronal action potentials has been limited by the lack of equally efficient tools for membrane hyperpolarization. We describe anion channel rhodopsins (ACRs), a family of light-gated anion channels from cryptophyte algae that provide highly sensitive and efficient membrane hyperpolarization and neuronal silencing through light-gated chloride conduction. ACRs strictly conducted anions, completely excluding protons and larger cations, and hyperpolarized the membrane of cultured animal cells with much faster kinetics at less than one-thousandth of the light intensity required by the most efficient currently available optogenetic proteins. Natural ACRs provide optogenetic inhibition tools with unprecedented light sensitivity and temporal precision.

  17. Anion exchangers with branched functional ion exchange layers of different hydrophilicity for ion chromatography.

    Science.gov (United States)

    Shchukina, O I; Zatirakha, A V; Smolenkov, A D; Nesterenko, P N; Shpigun, O A

    2015-08-21

    Novel polystyrene-divinylbenzene (PS-DVB) based anion exchangers differing from each other in the structure of the branched functional ion exchange layer are prepared to investigate the role of linker and functional site on ion exchange selectivity. The proposed method of synthesis includes the obtaining of aminated PS-DVB particles by means of their acylation with following reductive amination with methylamine. Further modification of the obtained secondary aminogroups is provided by the alkylation with either 1,4-butanediol diglycidyl ether (1,4-BDDGE) or resorcinol diglycidyl ether (RDGE), which form the linkers of different hydrophobicity, and amination of terminal epoxide rings with trimethylamine (TMA), dimethylethanolamine (DMEA), methyldiethanolamine (MDEA) or triethanolamine (TEA). The variation of the structure and hydrophobicity of the linker and terminal quaternary ammonium sites in the functional layer allows the alteration of selectivity and separation efficiency of the obtained adsorbents. The ion exchange selectivity and separation efficiency of the anion exchangers are evaluated using the model mixtures of anions (F(-), HCOO(-), Cl(-), NO2(-), Br(-), NO3(-), HPO4(2-) and SO4(2-)) in potassium hydroxide eluents. The adsorbents show the decrease of selectivity with increasing the hydrophilicity of the terminal functional site. The anion exchangers having more flexible and hydrophilic 1,4-BDDGE linker provide smaller separation factors for most of the analytes as compared with RDGE-containing adsorbents with the same terminal ion exchange sites, but are characterized with higher column efficiencies and better peak symmetry for polarizable anions. In case of 1,4-BDDGE-modified anion exchangers of the particle size of 3.3μm functionalized with DMEA and MDEA the calculated values of column efficiencies for polarizable NO3(-) and Br(-) are up to 49,000 and 53,000N/m, respectively, which is almost twice higher than the values obtained for the RDGE

  18. Luminescent lanthanide complexes of a bis-bipyridine-phosphine-oxide ligand as tools for anion detection.

    Science.gov (United States)

    Charbonnière, Loïc J; Ziessel, Raymond; Montalti, Marco; Prodi, Luca; Zaccheroni, Nelsi; Boehme, Christian; Wipff, Georges

    2002-07-01

    The Gd(3+), Tb(3+), and Eu(3+) complexes of a bis-bipyridine-phenylphosphine oxide ligand PhP(O)(bipy)(2) 1 (bipy for 6-methylene-6'-methyl-2,2'-bipyridine) have been synthesized. In acetonitrile solutions at room temperature, the Tb(3+) and Eu(3+) complexes show a metal-centered luminescence, indicative of an efficient energy transfer from the two bipy subunits to the Ln center. The photophysical properties drastically depend on the nature of the anions present in solution. In particular, addition of 2 equiv of nitrate anions to a solution containing the [Ln.1](OTf-)(3) leads to an 11-fold increase of the luminescence intensity for the Eu(3+) and a 7-fold increase for the Tb(3+) complexes. Similar effects are provided with Cl-, F-, and CH(3)COO- anions. UV-vis titration experiments were used to determine association constants for binding of, respectively, one, two, and three anions. Stepwise anion addition has also been investigated on the molecular level using quantum mechanical (QM) calculations for the Eu complexes. These calculations reproduce the experimental findings, especially if solvent molecule addition is taken into account. The X-ray crystal structure of the nitrate salt of the Tb complex, as well as QM calculation of a similar Eu complex, demonstrates the coordination of three nitrate anions in a bidentate mode and the step-by-step relegation of the bipy subunits in the second coordination sphere. These features give valuable insights into the mechanism of the overall light amplification process. PMID:12083932

  19. Marine sediment toxicity identification evaluation methods for the anionic metals arsenic and chromium.

    Science.gov (United States)

    Burgess, Robert M; Perron, Monique M; Cantwell, Mark G; Ho, Kay T; Pelletier, Marguerite C; Serbst, Jonathan R; Ryba, Stephan A

    2007-01-01

    Marine sediments accumulate a variety of contaminants and, in some cases, demonstrate toxicity because of this contamination. Toxicity identification evaluation (TIE) methods provide tools for identifying the toxic chemicals causing sediment toxicity. Currently, whole-sediment TIE methods are not available for anionic metals like arsenic and chromium. In the present paper, we describe two new anion-exchange resins used in the development of whole-sediment TIE methods for arsenic and chromium. Resins were shown to reduce whole-sediment toxicity and overlying water concentrations of the anionic metals. Sediment toxicity, expressed as the median lethal concentration, was reduced by a factor of two to a factor of nearly six between amended sediment treatments containing resin and those without resin. Aqueous concentrations of arsenic and chromium in the toxicity exposures decreased to less than the detection limits or to concentrations much lower than those measured in treatments without resin. Interference studies indicated that the anion-exchange resins had no significant effect on concentrations of the representative pesticide endosulfan and minimal effects on concentrations of ammonia. However, the anion-exchange resins did significantly reduce the concentrations of a selection of cationic metals (Cd, Cu, Ni, Pb, and Zn). These data demonstrate the utility of anion-exchange resins for determining the contribution of arsenic and chromium to whole-sediment toxicity. The present results also indicate the importance of using TIE methods in a formal TIE structure to ensure that results are not misinterpreted. These methods should be useful in the performance of marine whole-sediment TIEs.

  20. Self-assembled metalla-bowls for selective sensing of multi-carboxylate anions.

    Science.gov (United States)

    Mishra, Anurag; Vajpayee, Vaishali; Kim, Hyunuk; Lee, Min Hyung; Jung, Hyunji; Wang, Ming; Stang, Peter J; Chi, Ki-Whan

    2012-01-28

    Two new tetranuclear cationic metalla-bowls 4 and 5 were self-assembled from a bis-pyridine amide ligand (H(2)L) (1) and arene-ruthenium acceptors, [(Ru(2)(μ-η(4)-C(2)O(4))(η(6)-p-cymene)(2)](O(3)SCF(3))(2) (2) and [Ru(2)(dhnd)(η(6)-p-cymene)(2)](O(3)SCF(3))(2) (dhnd = 6,11-dihydroxy-5,12-naphthacenedionato) (3), respectively. The metalla-bowls were characterized by multinuclear NMR, ESI-MS, UV-Vis spectroscopy, and single crystal X-ray diffraction study of 4. The crystal structure of 4 reveals unambiguous proof for the molecular shape of the metalla-bowl and the encapsulation of one triflate anion in the cavity through hydrogen bonding. The metalla-bowl 5 has been evaluated for anion binding studies by use of amide ligand as a hydrogen bond donor and arene-Ru acceptor as a signalling unit. UV-Vis titration studies showed that 5 selectively binds with multi-carboxylate anions such as oxalate, tartrate and citrate in a 1 : 1 fashion with high binding constants of 4.0-5.5 × 10(4) M(-1). Furthermore, the addition of multi-carboxylate anions into a solution of 5 gave rise to a large enhancement of fluorescence intensity attributable to the blocking of a photo-induced electron transfer process from the arene-ruthenium moiety to the amidic donor in 5. However, the fluorescence intensity almost remains unchanged upon addition of other anions including F(-), Cl(-), PF(6)(-), MeCOO(-), NO(3)(-) and PhCOO(-), as identically seen in the UV-Vis titration experiments, pointing to the high selectivity of 5 for the sensing of multi-carboxylate anions.

  1. Anion-induced increases in the rate of colchicine binding to tubulin.

    Science.gov (United States)

    Bhattacharyya, B; Wolff, J

    1976-06-01

    The rate of binding of colchicine to tubulin to tubulin is enhanced by certain anions. Among the inorganic anions tested, only sulfate was effective. The organic anions include mostly dicarboxylic acids, among which tartrate was the most effective. This effect occurs onlt at low concentrations of colchicine (less than 0.6 X 10(-5) M). The rate increase dor sulfate and L-(+)-tartrate is ca. 2.5-fold at 1.0 mM and plateaus at a limiting value of ca. 4-fold at 100mM. The overall dissociation rate of the colchicine from the complex, which includes both the true rate of dissociation and the rate of irreversible denaturation of tubulin, is not influenced by 1.0 mM tartrate. The affinity constants for colchicine determined from the rate constants are 8.7 X 10(6) and 2.1 X 10(7) M-1 in the absence and the presence of 1.0 mM L-(+)-tartrate. The limiting value is 3.2 X 10(7) M-1. The affinity constant calculated from steady-state measurements is 3.2 X 10(6) M-1 with or without anions. The binding of other ligands like podophyllotoxin, vinblastine, and 1 -anilino-8-naphthalenesulfonate to tubulin is not affected by tartrate. No major conformational changes resulting from anion treatment could be detected by circular dichroism or intrinsic fluorescence. However, the ability of tubulin to polymerize is inhibited by L-(+)-tartrate at concentrations that increase the rate of colchicine binding. We conclude that anions must have a local effect at or near the binding site which enhances the binding rate of colchicine and which may be related to inhibition of polymerization.

  2. Anions Analysis in Ground and Tap Waters by Sequential Chemical and CO2-Suppressed Ion Chromatography

    Directory of Open Access Journals (Sweden)

    Glen Andrew D. De Vera

    2011-06-01

    Full Text Available An ion chromatographic method using conductivity detection with sequential chemical and CO2 suppression was optimized for the simultaneous determination of fluoride, chloride, bromide, nitrate,phosphate and sulfate in ground and tap water. The separation was done using an anion exchange column with an eluent of 3.2 mM Na2CO3 and 3.2 mM NaHCO3 mixture. The method was linear in the concentration range of 5 to 300 μg/L with correlation coefficients greater than 0.99 for the six inorganic anions. The method was also shown to be applicable in trace anions analysis as given by the low method detection limits (MDL. The MDL was 1μg/L for both fluoride and chloride. Bromide, nitrate, phosphate and sulfate had MDLs of 7 μg/L, 10 μg/L, 9 μg/L and 2 μg/L, respectively. Good precision was obtained as shown in the relative standard deviation of 0.1 to 12% for peak area and 0.1 to 0.3% for retention time. The sensitivity of the method improved with the addition of CO2 suppressor to chemical suppression as shown in the lower background conductivity and detection limits. The recoveries of the anions spiked in water at 300 μg/L level ranged from 100 to 104%. The method was demonstrated to be sensitive, accurate and precise for trace analysis of the six anions and was applied in the anions analysis in ground and tap waters in Malolos, Bulacan. The water samples were found to contain high concentrations of chloride of up to 476 mg/L followed by sulfate (38 mg/L, bromide (1 mg/L, phosphate (0.4 mg/L, fluoride (0.2 mg/L and nitrate (0.1 mg/L.

  3. The 2Πg shape resonance of acetylene anion: an investigation with the RAC method

    Science.gov (United States)

    Čurík, Roman; Paidarová, Ivana; Horáček, Jiří

    2016-07-01

    Recently developed method of regularized analytic continuation (RAC) is applied to determination of the 2Πg resonance of acetylene anion. The method is based on continuation of the electron affinities calculated for the anion in presence of an external perturbation field. Its independence on the correlation treatment of the many-electron system allows application of accurate coupled-clusters methods for electronic structure calculations utilized in determination of the resonance position and width. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  4. Synthesis and Anion Recognition of Novel Molecular Tweezer Receptors Based on Carbonyl Thiosemicarbazide for Fluoride Ions

    Institute of Scientific and Technical Information of China (English)

    WEI,Wei; ZHANG,You-Ming; WEI,Tai-Bao

    2008-01-01

    Three title compounds have been designed and synthesized in high yields as novel anion receptors, which show a higher selectivity for F- than other halide ions. The binding properties for fluoride ions of the receptors have been examined by UV-Vis and 1H NMR spectroscopy, indicating that a 1 : 1 stoichiometry complex is formed between the receptors and fluoride ions through hydrogen bonding interactions in DMSO solution. In addition, because these receptors have more binding points, they have better binding properties for anions than the molecular tweezer receptors based on thiourea we reported last time.

  5. Source Attribution of Cyanides using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics

    Energy Technology Data Exchange (ETDEWEB)

    Mirjankar, Nikhil S.; Fraga, Carlos G.; Carman, April J.; Moran, James J.

    2016-01-08

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs) are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. In a previous study, anionic impurity profiles developed using high performance ion chromatography (HPIC) were demonstrated as CAS for matching samples from eight potassium cyanide (KCN) stocks to their reported countries of origin. Herein, a larger number of solid KCN stocks (n = 13) and, for the first time, solid sodium cyanide (NaCN) stocks (n = 15) were examined to determine what additional sourcing information can be obtained through anion, carbon stable isotope, and elemental analyses of cyanide stocks by HPIC, isotope ratio mass spectrometry (IRMS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), respectively. The HPIC anion data was evaluated using the variable selection methods of Fisher-ratio (F-ratio), interval partial least squares (iPLS), and genetic algorithm-based partial least squares (GAPLS) and the classification methods of partial least squares discriminate analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminate analysis (SVMDA). In summary, hierarchical cluster analysis (HCA) of anion impurity profiles from multiple cyanide stocks from six reported country of origins resulted in cyanide samples clustering into three groups: Czech Republic, Germany, and United States, independent of the associated alkali metal (K or Na). The three country groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries with known solid cyanide factories. Both the anion and elemental CAS are believed to originate from the aqueous alkali hydroxides used in cyanide manufacture. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). The carbon isotope CAS is believed to

  6. Copper Complexes of Anionic Nitrogen Ligands in the Amidation and Imidation of Aryl Halides

    OpenAIRE

    Tye, Jesse W.; Weng, Zhiqiang; Johns, Adam M.; Incarvito, Christopher D.; Hartwig, John F.

    2008-01-01

    Copper(I) imidate and amidate complexes of chelating N,N-donor ligands, which are proposed intermediates in copper-catalyzed amidations of aryl halides, have been synthesized and characterized by X-ray diffraction and detailed solution-phase methods. In some cases, the complexes adopt neutral, three-coordinate trigonal planar structures in the solid state, but in other cases they adopt an ionic form consisting of an L2Cu+ cation and a CuX2− anion. A tetraalkylammonium salt of the CuX2− anion ...

  7. MRP3, an organic anion transporter able to transport anti-cancer drugs

    OpenAIRE

    Kool, Marcel; Van Der Linden, Marcel; de Haas, Marcel; Scheffer, George L.; de Vree, J. Marleen L.; Smith, Alexander J.; Jansen, Gerrit; Peters, Godefridus J; Ponne, Nico; Scheper, Rik J.; Elferink, Ronald P. J. Oude; Baas, Frank; Borst, Piet

    1999-01-01

    The human multidrug-resistance protein (MRP) gene family contains at least six members: MRP1, encoding the multidrug-resistance protein; MRP2 or cMOAT, encoding the canalicular multispecific organic anion transporter; and four homologs, called MRP3, MRP4, MRP5, and MRP6. In this report, we characterize MRP3, the closest homolog of MRP1. Cell lines were retrovirally transduced with MRP3 cDNA, and new monoclonal antibodies specific for MRP3 were generated. We show that MRP3 is an organic anion ...

  8. THE TESTS AND MECHANISM ABOUT SODIUM IONS FROM AN ANION EXCHANGER

    Institute of Scientific and Technical Information of China (English)

    ZhuXingbao; YuJinchun; 等

    1996-01-01

    There exists a universal phenomena that sodium ions are leaked from the strong basic anion exdchanger in operation,which has been puzzling the researchers working in the field of water treatment for years.It is well known that the leakage of sodium ions will seriously affect the pruity of effluent.On the basis of lots of laboratory and industrial experiments,the mechanism of the sodium ions leaked from an anion exchanger has been preliminarily made out and some new chemical reaction equations as well as some improving measures have been put forward in this article.

  9. Function of the anion transporter AtCLC-d in the trans-Golgi network

    OpenAIRE

    von der Fecht-Bartenbach, Jennifer; Bogner, Martin; Krebs, Melanie; Stierhof, York-Dieter; Schumacher, Karin; Ludewig, Uwe

    2007-01-01

    Anion transporting proteins of the CLC type are involved in anion homeostasis in a variety of organisms. CLCs from Arabidopsis have been shown to participate in nitrate accumulation and storage. In this study, the physiological role of the functional chloride transporter AtCLC-d from Arabidopsis was investigated. AtCLC-d is weakly expressed in various tissues, including the root. When transiently expressed as a GFP fusion in protoplasts, it co-localized with the VHA-a1 subunit of the proton-t...

  10. Formation and Decay of the Dehydrogenated Parent Anion upon Electron Attachment to Dialanine

    OpenAIRE

    Gschliesser, David; Vizcaino, Violaine; Probst, Michael; Scheier, Paul; Denifl, Stephan

    2012-01-01

    Abstract The dehydrogenated parent anion [M−H]− is one of the most dominant anions formed in dissociative electron attachment to various small biomolecules like nucleobases and single amino acids. In the present study, we investigate the [M−H]− channel for the dipeptide dialanine by utilizing an electron monochromator and a two-sector-field mass spectrometer. At electron energies below 2 eV, the measured high-resolution ion-efficiency curve has a different shape to that for the single amino a...

  11. Reactions between the (SO·4-) radical and some common anions in atmospheric aqueous droplets

    Institute of Scientific and Technical Information of China (English)

    OUYANG Bin; FANG Hao-jie; ZHU Cheng-zhu; DONG Wen-bo; HOU Hui-qi

    2005-01-01

    The rate constants of reactions between the SO4·- radical and some common anions in atmospheric aqueous droplets e.g. Cl-,NO3-, HSO3- and HCO3- were determined using the laser flash photolysis technique. Absorption spectra of SO4·- and the product radicals were also reported. The chloride ion was evaluated among all the anions to be the most efficient scavenger of SO4·- . The results may supply useful information for a better understanding of the vigorous radical-initiated reactions in atmospheric aqueous droplets such as clouds, rains or fogs.

  12. Impact of powdered activated carbon and anion exchange resin on photocatalytic treatment of textile wastewater

    OpenAIRE

    Dhas, Preethi Grace Theva Neethi; Gulyas, Holger; Otterpohl, Ralf

    2015-01-01

    In order to clarify the impact of activated carbon and anion exchange resin on photocatalytic oxidation (PCO) of textile industry wastewater, TiO2-based PCO was investigated with aqueous solutions containing the reactive dye Reactive Blue 4 (RB4) and with a textile dye house effluent in the absence and in the presence of powdered activated carbon (PAC) and the anion exchange resin Lewatit MP 500. Addition of Lewatit improved RB4 removal to a larger extent than PAC addition. Contrasting to chl...

  13. Modified anion-exchange method for determination of thorium in uranium based materials

    International Nuclear Information System (INIS)

    This paper details a modified anion-exchange method for estimation of thorium in uranium based samples like uranium dioxide powders, pellets and uranyl nitrate solutions. The method involves separation of thorium from uranium from 3M commercial grade HCl containing 15% NaCl through an anion-exchange resin. The uranium free effluent containing the analyte(thorium) is determined spectrophotometrically by exploiting absorption of the thorium-arsenazo III complex at 660 nm. The method has a precision of about ±2% at 50 ppm level. (author). 3 refs., 1 tab

  14. Synthesis and Characterization of Periodic Mesoporous Organosilicas as Anion-Exchance Resins for Perrhenate Adsorption.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byunghwan [Korea Institute of Industrial Technology, ChonAn, Korea; Im, Hee-Jung [ORNL; Luo, Huimin [ORNL; Hagaman, Edward {Ed} W [ORNL; Dai, Sheng [ORNL

    2005-01-01

    A new methodology to immobilize ionic liquids through the use of a bridged silsesquioxane N-(3-triethoxysilylpropyl), N(3)-3-trimethoxysilylpropyl-4,5-dihydroimidazolium iodide that incorporates an ionic functionality for the assembly of novel periodic mesoporous organosilica (PMO) materials has been developed. The resulting PMO materials were investigated for use as novel anion exchange resins for the separation of perrhenate anions in aqueous solution. As compared with cetyltrimethylammonium chloride, 1-hexadecane-3-methylimidazolium bromide has been demonstrated to be a more efficient surfactant template for the generation of mesopores and surface areas for such PMO materials.

  15. Resonance Raman Spectrum of the Transient (SCN)2 Free Radical Anion

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, N. H.; Pagsberg, Palle Bjørn;

    1979-01-01

    The resonance Raman spectrum of the transient species (λmax = 475 nm, τ½ = 1.6 μs) formed by pulse radiolysis of aqueous solutions of thiocyanate, SCN2−, is reported. The spectrum is discussed in terms of the previous assignment of this transient to the radical anion, (SCN)−2. The observed vibrat...... vibrational frequencies of the radical anion are consistent with substantial weakening of the S---S and the Ctriple bond; length as m-dashN bonds are compared with neutral thiocyanogen....

  16. Discovering lead-free perovskite solar materials with a split-anion approach

    Science.gov (United States)

    Sun, Yi-Yang; Shi, Jian; Lian, Jie; Gao, Weiwei; Agiorgousis, Michael L.; Zhang, Peihong; Zhang, Shengbai

    2016-03-01

    Organic-inorganic hybrid perovskite solar materials, being low-cost and high-performance, are promising for large-scale deployment of the photovoltaic technology. A key challenge that remains to be addressed is the toxicity of these materials since the high-efficiency solar cells are made of lead-containing materials, in particular, CH3NH3PbI3. Here, based on first-principles calculation, we search for lead-free perovskite materials based on the split-anion approach, where we replace Pb with non-toxic elements while introducing dual anions (i.e., splitting the anion sites) that preserve the charge neutrality. We show that CH3NH3BiSeI2 and CH3NH3BiSI2 exhibit improved band gaps and optical absorption over CH3NH3PbI3. The split-anion approach could also be applied to pure inorganic perovskites, significantly enlarging the pool of candidate materials in the design of low-cost, high-performance and environmentally-friendly perovskite solar materials.Organic-inorganic hybrid perovskite solar materials, being low-cost and high-performance, are promising for large-scale deployment of the photovoltaic technology. A key challenge that remains to be addressed is the toxicity of these materials since the high-efficiency solar cells are made of lead-containing materials, in particular, CH3NH3PbI3. Here, based on first-principles calculation, we search for lead-free perovskite materials based on the split-anion approach, where we replace Pb with non-toxic elements while introducing dual anions (i.e., splitting the anion sites) that preserve the charge neutrality. We show that CH3NH3BiSeI2 and CH3NH3BiSI2 exhibit improved band gaps and optical absorption over CH3NH3PbI3. The split-anion approach could also be applied to pure inorganic perovskites, significantly enlarging the pool of candidate materials in the design of low-cost, high-performance and environmentally-friendly perovskite solar materials. Electronic supplementary information (ESI) available: Detailed descriptions on

  17. Charge and anion ordering phase transitions in (TMTTF){sub 2}X salt conductors

    Energy Technology Data Exchange (ETDEWEB)

    Nad, F. [Centre de Recherches sur les Tres Basses Temperatures, laboratoire associe a l' Universite Joseph Fourier, CNRS, BP 166, Grenoble (France); Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow (Russian Federation); Monceau, P. [Centre de Recherches sur les Tres Basses Temperatures, laboratoire associe a l' Universite Joseph Fourier, CNRS, BP 166, Grenoble (France); Carcel, C.; Fabre, J.M. [Heterochimie et Materiaux Organiques, ENSCM/ESA, Montpellier (France)

    2001-07-23

    We report measurements of the low frequency conductivity and dielectric permittivity of quasi-one-dimensional organic (TMTTF){sub 2}X salts with non-centrosymmetrical anions X=ReO{sub 4} and SCN. We show that the 'structureless transition' at 227.5 K in (TMTTF){sub 2}ReO{sub 4} is due to charge ordering and has a ferroelectric character. The anion ordering transition strongly affects the dielectric response: it suppresses the polarizability in (TMTTF){sub 2}ReO{sub 4} and induces probably an antiferroelectric state in (TMTTF){sub 2}SCN. (author). Letter-to-the-editor.

  18. Purification and Characterization of Two Voltage-Dependent Anion Channel Isoforms from Plant Seeds1

    Science.gov (United States)

    Abrecht, Helge; Wattiez, Ruddy; Ruysschaert, Jean-Marie; Homblé, Fabrice

    2000-01-01

    Mitochondria were isolated from imbibed seeds of lentil (Lens culinaris) and Phaseolus vulgaris. We copurified two voltage-dependent anion channel from detergent solubilized mitochondria in a single purification step using hydroxyapatite. The two isoforms from P. vulgaris were separated by chromatofocusing chromatography in 4 m urea without any loss of channel activity. Channel activity of each isoform was characterized upon reconstitution into diphytanoyl phosphatidylcholine planar lipid bilayers. Both isoforms form large conductance channels that are slightly anion selective and display cation selective substates. PMID:11080295

  19. Purification and characterization of two voltage-dependent anion channel isoforms from plant seeds.

    Science.gov (United States)

    Abrecht, H; Wattiez, R; Ruysschaert, J M; Homblé, F

    2000-11-01

    Mitochondria were isolated from imbibed seeds of lentil (Lens culinaris) and Phaseolus vulgaris. We copurified two voltage-dependent anion channel from detergent solubilized mitochondria in a single purification step using hydroxyapatite. The two isoforms from P. vulgaris were separated by chromatofocusing chromatography in 4 M urea without any loss of channel activity. Channel activity of each isoform was characterized upon reconstitution into diphytanoyl phosphatidylcholine planar lipid bilayers. Both isoforms form large conductance channels that are slightly anion selective and display cation selective substates.

  20. Separation of thorium and uranium in nitric acid solution using silica based anion exchange resin.

    Science.gov (United States)

    Chen, Yanliang; Wei, Yuezhou; He, Linfeng; Tang, Fangdong

    2016-09-30

    To separate thorium and uranium in nitric acid solution using anion exchange process, a strong base silica-based anion exchange resin (SiPyR-N4) was synthesized. Batch experiments were conducted and the separation factor of thorium and uranium in 9M nitric acid was about 10. Ion exchange chromatography was applied to separate thorium and uranium in different ratios. Uranium could be eluted by 9M nitric acid and thorium was eluted by 0.1M nitric acid. It was proved that thorium and uranium can be separated and recovered successfully by this method.

  1. Importance of the nature of anions in lysozyme crystallisation correlated with protein net charge variation.

    Science.gov (United States)

    Retailleau, Pascal; Ducruix, Arnaud; Riès-Kautt, Madeleine

    2002-10-01

    Hofmeister anion series are studied to examine the coupled influence of pH and ionic strength on the solubility of previously desalted lysozyme. Solubility curves are measured at pH 4.3 and 8.3 and 18 degrees C for nitrate, para-toluenesulfonate, citrate, sulphate, phosphate, and acetate. Extreme low ionic strength is explored, confirming the decrease of lysozyme solubility while increasing the protein net charge and the ionic strength. The classification of specific salt effects takes into account the valence of the anions with respect to the protein net charge. PMID:12351865

  2. Alignment of a Molecular Anion via a Shape Resonance in Near-Threshold Photodetachment

    Science.gov (United States)

    Lu, Zhou; Continetti, Robert E.

    2007-09-01

    One-color two-photon photodetachment of HOCO- at Ehν=1.60eV accompanied by a measurement of the photoelectron angular distribution (PAD) is used to illustrate a novel approach to the alignment of a molecular anion. A quantitative analysis of the PAD reveals this alignment process is associated with a temporary anion formed by a p-wave shape resonance and the PAD in the two-photon signal is a result of interfering s- and d-partial waves within the atomic approximation. The extracted intensity and phase shift of the partial waves are consistent with the Wigner threshold law for photodetachment.

  3. Methods of using ionic liquids having a fluoride anion as solvents

    Science.gov (United States)

    Pagoria, Philip; Maiti, Amitesh; Gash, Alexander; Han, Thomas Yong; Orme, Christine; Fried, Laurence

    2011-12-06

    A method in one embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having a fluoride anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of about 90.degree. C. or less during the contacting. A method in another embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having an acetate or formate anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of less than about 90.degree. C. during the contacting.

  4. Preparation of anionic clay-birnessite manganese oxide composites by interlayer oxidation of oxalate ions by permanganate

    Energy Technology Data Exchange (ETDEWEB)

    Arulraj, James [Materials Research Group, Department of Chemistry, St. Joseph' s College, 36 Langford Road, Bangalore 560 027 (India); Rajamathi, Michael, E-mail: mikerajamathi@rediffmail.com [Materials Research Group, Department of Chemistry, St. Joseph' s College, 36 Langford Road, Bangalore 560 027 (India)

    2013-02-15

    Oxalate intercalated anionic clay-like nickel zinc hydroxysalt was obtained starting from nickel zinc hydroxyacetate, Ni{sub 3}Zn{sub 2}(OH){sub 8}(OAc){sub 2}{center_dot}2H{sub 2}O, by anion exchange. The intercalated oxalate species was reacted with potassium permanganate in such a way that the layered manganese oxide formed was within the interlayer region of the anionic clay resulting in a layered composite in which the negative charges on the birnessite type manganese oxide layers compensate the positive charges on the anionic clay layers. Birnessite to anionic clay ratio could be varied by varying the reaction time or the amount of potassium permanganate used. - Graphical abstract: Nickel zinc hydroxyoxalate was reacted with potassium permanganate to get nickel zinc hydroxide birnessite composites in which the positive charges on the hydroxide layers are neutralized by the negative charges on birnessite layers. Highlights: Black-Right-Pointing-Pointer Anionic and cationic layered solid composites prepared. Black-Right-Pointing-Pointer Ni-Zn hydroxyoxalate reacted with KMnO{sub 4} to deposit MnO{sub 2} in the interlayer. Black-Right-Pointing-Pointer Birnessite layers coexist with anionic clay layers in the composites. Black-Right-Pointing-Pointer Birnessite/anionic clay ratio controlled by amount of KMnO{sub 4} used and reaction time.

  5. Chlorine isotope enrichment on a strong alkaline anion exchanger in dependence of type and concentration of the strange electrolytic solution

    International Nuclear Information System (INIS)

    Chlorine isotope enrichment for heterogenous ionexchange equilibria was studied. The dependence of element separation effects on the anion of the strange electrolyte (for same cation), on the cation of the strange electrolyte (for same anion), on the concentration of the strange electrolyte and also on the acetone: water ratio of the solvent was investigated. (orig./HBR)

  6. Induction of Apoptosis by Superoxide Anion and the Protective Effects of Selenium and Vitamin E

    Institute of Scientific and Technical Information of China (English)

    GUOLING; XUEAN-NA; 等

    2001-01-01

    Objective:The purpose of this study is to investigate the effect of superoxide anion on the apoptosis of cultured fibroblasts and the protective role of seleium and Vitamin E.Methods:Cultured fibroblasts(NIH3T3),with or without selenium or vitamin E in the medium,were treated by superoxide anion produced by xanthine/xanthine oxidase reaction system and changes in cell structure and DNA were observed microscopically and electrophoretically,Results:Apoptosis was observed when superoxide anion at a concentration of 5nmol/L or 10nmol/L had acted on the fibroblasts for 5-10h.Selenium and Vitamin E in the medium inhibited the apoptosis significantly when their concentrations reached 1.15mol/L and 2.3mol/L respectively.Concleusion:selenium and vitamin Ehave protective effect against the apoptosis induced by superoxide anion.The effect of selenium is more remakable than that of vitamin E.

  7. Electrochemical examination of the ascorbic acid radical anion in non-aqueous electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, M.; Honda, K.; Kondo, T.; Rao, T.N.; Tryk, D.A.; Fujishima, A

    2002-10-15

    A quasi-reversible redox reaction involving ascorbic acid was observed in non-aqueous electrolytes at conductive diamond electrode. The chemical reversibility of these reactions is consistent with ascorbic acid being reduced to the ascorbic acid radical anion in a one-electron process, with subsequent reoxidation to ascorbic acid. This is the first report on the electrochemical production of the ascorbic acid radical anion in non-aqueous electrolytes. Ascorbyl 6-stearate and 4-hydroxy 2(5H)-furanone, which have somewhat similar structures as ascorbic acid, also showed one-electron transfer reduction reaction producing radicals with a single negative charge, suggesting that these compounds follow the same electrochemical behavior as ascorbic acid. The double bond and hydroxyl substituent on the five-membered ring are shown to be necessary for the stabilization of the radical anions. It was confirmed by the calculation of the total energy using molecular orbital methods that resonance structures involving the double-bond and hydroxyl group provide significant stabilization of the radical anions. Electrochemical preparation may be a useful method for the detailed study of radicals, their molecular structure and reactivity.

  8. Electrochemical examination of the ascorbic acid radical anion in non-aqueous electrolytes

    International Nuclear Information System (INIS)

    A quasi-reversible redox reaction involving ascorbic acid was observed in non-aqueous electrolytes at conductive diamond electrode. The chemical reversibility of these reactions is consistent with ascorbic acid being reduced to the ascorbic acid radical anion in a one-electron process, with subsequent reoxidation to ascorbic acid. This is the first report on the electrochemical production of the ascorbic acid radical anion in non-aqueous electrolytes. Ascorbyl 6-stearate and 4-hydroxy 2(5H)-furanone, which have somewhat similar structures as ascorbic acid, also showed one-electron transfer reduction reaction producing radicals with a single negative charge, suggesting that these compounds follow the same electrochemical behavior as ascorbic acid. The double bond and hydroxyl substituent on the five-membered ring are shown to be necessary for the stabilization of the radical anions. It was confirmed by the calculation of the total energy using molecular orbital methods that resonance structures involving the double-bond and hydroxyl group provide significant stabilization of the radical anions. Electrochemical preparation may be a useful method for the detailed study of radicals, their molecular structure and reactivity

  9. Preparation of the Cyclopentazole Anion in the Bulk: A Computational Study.

    Science.gov (United States)

    Geiger, Uzi; Haas, Yehuda

    2016-07-01

    The cyclopentazole anion (cyclo-N5(-)), calculated to be a stable species, was prepared in the gas phase but attempts to synthesize it in the bulk have so far been futile. An aryl pentazole radical anion was suggested as a promising precursor in the gas phase. It is shown computationally that the radical anion (which may be prepared by reduction of the phenyl pentazole neutral) may indeed be used to form the cyclopetazolate anion in the gas phase and in liquid solution, alongside and in competition with the extrusion of N2 to produce the corresponding azide. In the gas phase, the C-N dissociation yields are very low due to much more efficient detachment of an electron. In polar solvents, ionization is suppressed and the primary yields of the two competing reactions are similar. The reaction must be carried out at low temperatures and special measures have to be taken to avoid recombination of the nascent cyclo-N5(-) with the geminate phenyl radical. A possible remedy is to use a solvent that reacts efficiently with the phenyl radical by H atom transfer. PMID:27028051

  10. Cation-π vs anion-π interactions: a complete π-orbital analysis

    Science.gov (United States)

    Garau, Carolina; Frontera, Antonio; Quiñonero, David; Ballester, Pablo; Costa, Antoni; Deyà, Pere M.

    2004-11-01

    A complete orbital analysis of two isoelectronic complexes of trifluorobenzene (TFB), TFB ⋯ F - and TFB ⋯ Na +, as models for anion-π and cation-π interactions, respectively, has been performed at the MP2/6-31++G** level of theory. There are important orbital differences between both interactions, which are discussed in detail herein.

  11. Ab initio search for global minimum structures of neutral and anionic B4H4 clusters

    International Nuclear Information System (INIS)

    Graphical abstract: Low-lying isomers of the B4H4 cluster found by sampling potential energy surface with the Coalescence Kick method. Research highlights: → B4H4 has a planar rather than a tetrahedral global minimum structure. → The B4H4- anion global minimum is a distorted tetrahedral structure. → Theoretical vertical detachment energies included here can help interpret future photoelectron spectroscopic study of the B4H4- anion. → Bonding analysis using AdNDP reveals 4-center bonding in B4H4 and B4H4- clusters. - Abstract: Potential energy surfaces of neutral and anionic B4H4 clusters were sampled using a Coalescence Kick method. A diverse set of global minimum structures and low-lying isomers was found for the studied clusters. Theoretical vertical electron detachment energies were calculated for the two lowest isomers of B4H4-, which could help to assign them in the future experimentally observed photoelectron spectra of the anion. Chemical bonding analysis for the global minimum structures and low-lying isomers of B4H4 and B4H4- was performed using the Adaptive Natural Density Partitioning method.

  12. Photodetachment as destruction mechanism for CN- and C3N- anions in circumstellar envelopes

    CERN Document Server

    Kumar, S S; Jindra, R; Best, T; Roucka, S; Geppert, W D; Millar, T J; Wester, R

    2013-01-01

    Absolute photodetachment cross sections of two anions of astrophysical importance CN- and C3N- were measured to be (1.18 +- (0.03)_stat (0.17)_sys) * 10^-17 cm^2 and (1.43 +- (0.14)_stat (0.37)_sys) * 10^-17 cm^2 respectively at the ultraviolet wavelength of 266 nm (4.66 eV). These relatively large values of the cross sections imply that photodetachment can play a major role in the destruction mechanisms of these anions particularly in photon-dominated regions. We have therefore carried out model calculations using the newly measured cross sections to investigate the abundance of these molecular anions in the cirumstellar envelope of the carbon-rich star IRC+10216. The model predicts the relative importance of the various mechanisms of formation and destruction of these species in different regions of the envelope. UV photodetachment was found to be the major destruction mechanism for both CN- and C3N- anions in those regions of the envelope, where they occur in peak abundance. It was also found that photodet...

  13. Anionic PPV polymerization from the sulfinyl precursor route : Block copolymer formation from sequential addition of monomers

    NARCIS (Netherlands)

    Cosemans, Inge; Vandenbergh, Joke; Voet, Vincent S. D.; Loos, Katja; Lutsen, Laurence; Vanderzande, Dirk; Junkers, Thomas

    2013-01-01

    The sulfinyl precursor route for the synthesis of poly(p-phenylene vinylene) (PPV) materials via an anionic polymerization procedure employing dedicated initiators is evaluated in depth. Reaction kinetics are investigated to gain more control over the polymerization, since polymerization proceeds to

  14. Experimental evidence for the functional relevance of anion-π interactions

    Science.gov (United States)

    Dawson, Ryan E.; Hennig, Andreas; Weimann, Dominik P.; Emery, Daniel; Ravikumar, Velayutham; Montenegro, Javier; Takeuchi, Toshihide; Gabutti, Sandro; Mayor, Marcel; Mareda, Jiri; Schalley, Christoph A.; Matile, Stefan

    2010-07-01

    Attractive in theory and confirmed to exist, anion-π interactions have never really been seen at work. To catch them in action, we prepared a collection of monomeric, cyclic and rod-shaped naphthalenediimide transporters. Their ability to exert anion-π interactions was demonstrated by electrospray tandem mass spectrometry in combination with theoretical calculations. To relate this structural evidence to transport activity in bilayer membranes, affinity and selectivity sequences were recorded. π-acidification and active-site decrowding increased binding, transport and chloride > bromide > iodide selectivity, and supramolecular organization inverted acetate > nitrate to nitrate > acetate selectivity. We conclude that anion-π interactions on monomeric surfaces are ideal for chloride recognition, whereas their supramolecular enhancement by π,π-interactions appears perfect to target nitrate. Chloride transporters are relevant to treat channelopathies, and nitrate sensors to monitor cellular signaling and cardiovascular diseases. A big impact on organocatalysis can be expected from the stabilization of anionic transition states on chiral π-acidic surfaces.

  15. A tetrastable naphthalenediimide: anion induced charge transfer, single and double electron transfer for combinational logic gates.

    Science.gov (United States)

    Ajayakumar, M R; Hundal, Geeta; Mukhopadhyay, Pritam

    2013-09-11

    Herein we demonstrate the formation of the first tetrastable naphthalenediimide (NDI, 1a) molecule having multiple distinctly readable outputs. Differential response of 1a to fluoride anions induces intramolecular charge transfer (ICT), single/double electron transfer (SET/DET) leading to a set of combinational logic gates for the first time with a NDI moiety. PMID:23752683

  16. Electron sharing and anion-π recognition in molecular triangular prisms.

    Science.gov (United States)

    Schneebeli, Severin T; Frasconi, Marco; Liu, Zhichang; Wu, Yilei; Gardner, Daniel M; Strutt, Nathan L; Cheng, Chuyang; Carmieli, Raanan; Wasielewski, Michael R; Stoddart, J Fraser

    2013-12-01

    Stacking on a full belly: Triangular molecular prisms display electron sharing among their triangularly arranged naphthalenediimide (NDI) redox centers. Their electron-deficient cavities encapsulate linear triiodide anions, leading to the formation of supramolecular helices in the solid state. Chirality transfer is observed from the six chiral centers of the filled prisms to the single-handed helices. PMID:24227594

  17. Structure and thermal evolution of Mg-Al layered double hydroxide containing interlayer organic glyphosate anions

    International Nuclear Information System (INIS)

    Layered double hydroxide (LDH) with the Mg2+/Al3+ molar ratio of 2.0 containing interlayer organic pesticide glyphosate anions (MgAl-Gly-LDH) has been synthesized by the use of anion exchange and coprecipitation routes. Intercalation experiments with glyphosate (Gly) reveal a correlation between the temperatures for thermal treatments and the types of reaction it undergoes with Gly. The grafting of the Gly anion onto hydroxylated sheets of LDH by moderate thermal treatments (hydrothermal treatments and calcinations) was confirmed by a combination of several techniques, including powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA-DTG), and 31P nuclear magnetic resonance (NMR). The thermal decomposition of MgAl-Gly-LDH results in the removal of loosely held interlayer water, grafting reaction between the interlayer anions and hydroxyl groups on the lattice of LDH, dehydroxylation of the lattice and decomposition of the interlayer species in succession, thus leading to a variety of crystallographic transitions

  18. Anion channels in Chara corallina tonoplast membrane: Calcium dependence and rectification

    NARCIS (Netherlands)

    Berecki, G.; Varga, Z.; Iren, F. van; Duijn, B. van

    1999-01-01

    Tonoplast K+ channels of Chara corallina are well characterized but only a few reports mention anion channels, which are likely to play an important role in the tonoplast action potential and osmoregulation of this plant. For experiments internodal cells were isolated. Cytoplasmic droplets were form

  19. Gel for simultaneous chemical imaging of anionic and cationic solutes using diffusive gradients in thin films.

    Science.gov (United States)

    Kreuzeder, Andreas; Santner, Jakob; Prohaska, Thomas; Wenzel, Walter W

    2013-12-17

    We report on a novel gel based on diffusive gradients in thin films (DGT) for the simultaneous measurement of cations and anions and its suitability for high resolution chemical imaging by using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The new high resolution mixed binding gel (HR-MBG) is based on zirconium-hydroxide and suspended particulate reagent-iminodiacetate (SPR-IDA) as resin materials which are embedded in an ether-based urethane polymer hydrogel. The use of this polymer hydrogel material allows the production of ultrathin, highly stable and tear-proof resin gel layers with superior handling properties compared to existing ultrathin polyacrylamide gels. The gel was characterized regarding its uptake kinetics, the anion and cation capacities, and the effects of pH, ionic strength, and aging on the performance of the HR-MBG. Our results demonstrate the capability of this novel gel for concomitant sampling of anions and cations. The suitability of this new gel type for DGT chemical imaging at submm spatial resolution in soils using LA-ICPMS is shown. 2D images of P, As, Co, Cu, Mn, and Zn distributions around roots of Zea mays L. demonstrate the new opportunities offered by the HR-MBG for high-resolution mapping of solute dynamics in soil and sediment hotspots, such as the rhizosphere, by simultaneous observation of anionic and cationic solute species.

  20. Studies concerning the anion ex-change resins catalyzed esterification of epichlorohydrin with organic acids

    Directory of Open Access Journals (Sweden)

    E.I. Muresan

    2009-09-01

    Full Text Available The paper studies the esterification of carboxylic acids with epichlorohydrin over two macroporous strong base anion exchange resins with different polymer matrix. For both resins, the influence of reaction parameters (temperature, catalyst loading, molar ratio on the reaction rate and the yields of the two isomeric esters were investigated.

  1. New disordering mode for TFSI- anions: the nonequilibrium, plastic crystalline structure of Et4NTFSI.

    Science.gov (United States)

    Henderson, Wesley A; Herstedt, Marie; Young, Victor G; Passerini, Stefano; De Long, Hugh C; Trulove, Paul C

    2006-02-20

    A new TFSI- anion disordering mode has been discovered in a supercooled plastic crystalline phase of Et4NTFSI, which may, in part, account for the low melting points of TFSI- salts with organic cations, thereby forming ionic liquids, and the intriguing properties of LiTFSI for lithium battery applications. PMID:16471945

  2. Organic anion exudation by lowland rice (Oryza sativa L.) at zinc and phosphorus deficiency

    NARCIS (Netherlands)

    Hoffland, E.; Wei, C.Z.; Wissuwa, M.

    2006-01-01

    The objectives of this paper were to determine (1) if lowland rice (Oryza sativa L.) plants respond similarly to low zinc (Zn) and phosphorus (P) availability by increased root exudation of low-molecular weight organic anions (LMWOAs) and (2) if genotypic variation in tolerance to low soil supply of

  3. Long-range intramolecular electron transfer in aromatic radical anions and binuclear transition metal complexes

    DEFF Research Database (Denmark)

    Kuznetsov, A. M.; Ulstrup, Jens

    1981-01-01

    Intramolecular electron transfer (ET) over distances up to about 10 Å between states in which the electron is localized on donor and acceptor groups by interaction with molecular or external solvent nuclear motion occurs, in particular, in two classes of systems. The excess electron in anionic ra...

  4. Halogen bonding-enhanced electrochemical halide anion sensing by redox-active ferrocene receptors.

    Science.gov (United States)

    Lim, Jason Y C; Cunningham, Matthew J; Davis, Jason J; Beer, Paul D

    2015-10-01

    The first examples of halogen bonding redox-active ferrocene receptors and their anion electrochemical sensing properties are reported. Halogen bonding was found to significantly amplify the magnitude of the receptor's metallocene redox-couple's voltammetric responses for halide sensing compared to their hydrogen bonding analogues in both acetonitrile and aqueous-acetonitrile solvent media. PMID:26289779

  5. Functional expression of pig renal organic anion transporter 3 (pOAT3).

    Science.gov (United States)

    Hagos, Yohannes; Braun, Isabella M; Krick, Wolfgang; Burckhardt, Gerhard; Bahn, Andrew

    2005-05-01

    With the cloning of pig renal organic anion transporter 1 (pOAT1) (Biochimie 84 (2002) 1219) we set up a model system for comparative studies of cloned and natively isolated membrane located transport proteins. Meanwhile, another transport protein involved in p-aminohippurate (PAH) uptake on the basolateral side of the proximal tubule cells was identified, designated organic anion transporter 3 (OAT3). To explore the contribution of pOAT1 to the PAH clearance in comparison to OAT3, it was the aim of this study to extend our model by cloning of the pig ortholog of OAT3. Sequence comparisons of human organic anion transporter 3 (hOAT3) with the expressed sequence tag (EST) database revealed a clone and partial sequence of the pig renal organic anion transporter 3 (pOAT3) ortholog. Sequencing of the entire open reading frame resulted in a protein of 543 amino acid residues encoded by 1632 base pairs (EMBL Acc. No. AJ587003). It showed high homologies of 81%, 80%, 76%, and 77% to the human, rabbit, rat, and mouse OAT3, respectively. A functional characterization of pOAT3 in Xenopus laevis oocytes yielded an apparent Km (Kt) for [3H]estrone sulfate of 7.8 +/- 1.3 microM. Moreover, pOAT3 mediated [3H]estrone sulfate uptake was almost abolished by 0.5 mM of glutarate, dehydroepiandosterone sulfate, or probenecid consistent with the hallmarks of OAT3 function.

  6. Formation of radical anions of radiosensitizers and related model compounds via electrospray ionization

    DEFF Research Database (Denmark)

    Feketeová, Linda; Albright, Abigail L; Sørensen, Brita Singers;

    2014-01-01

    Radiosensitizers are used in radiotherapy to enhance tumour control of radioresistant hypoxic tumours. While the detailed mechanism of radiosensitization is still unknown, the formation of radical anions is believed to be a key step. Thus understanding the ionization reactions of radiosensitizers...

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

    Science.gov (United States)

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

    2015-03-01

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

  8. "Anion clamp" allows flexible protein to impose coordination geometry on metal ions.

    Science.gov (United States)

    Wang, Minji; Lai, Tsz Pui; Wang, Li; Zhang, Hongmin; Yang, Nan; Sadler, Peter J; Sun, Hongzhe

    2015-05-01

    X-ray crystal structures of human serum transferrin (77 kDa) with Yb(III) or Fe(III) bound to the C-lobe and malonate as the synergistic anion show that the large Yb(III) ion causes the expansion of the metal binding pocket while octahedral metal coordination geometry is preserved, an unusual geometry for a lanthanide ion.

  9. Effect of lipid phase transition on the binding of anions to dimyristoylphosphatidylcholine liposomes.

    Science.gov (United States)

    Tatulian, S A

    1983-12-21

    Temperature dependence of the electrophoretic mobility of multilamellar liposomes prepared from dimyristoylphosphatidylcholine was measured in the presence of salts with different anions in aqueous solutions. It was established that specific binding of anions to liposome surface induced a pronounced zeta potential (electrostatic potential at the hydrodynamic plane of shear). A combination of Langmuir, Gouy-Chapman, and Boltzmann equations was used to describe the dependence of the zeta potential on the concentration of anions. The values of binding constants (K) and maximum numbers of binding sites per unit area (sigma max) were determined by this method. The sequence for anion affinities to liposome surface was found to be as follows: trinitrophenol greater than ClO-4 greater than I- greater than SCN- greater than Br- greater than NO-3 greater than Cl- approximately or equal to SO2-4. A sharp increase in the negative zeta potential was detected at the temperature of phase transition of the lipid from the gel to liquid-crystalline state. It was found that the parameter K did not change at lipid phase transition and the shifts in zeta potential might be due to alterations of sigma max. The binding sites were considered as defects in the package of lipid molecules in membranes. PMID:6652082

  10. A Supramolecular Sensing Platform for Phosphate Anions and an Anthrax Biomarker in a Microfluidic Device

    NARCIS (Netherlands)

    Eker, Bilge; Yilmaz, Mahmut Deniz; Schlautmann, Stefan; Gardeniers, Johannes G.E.; Huskens, Jurriaan

    2011-01-01

    A supramolecular platform based on self-assembled monolayers (SAMs) has been implemented in a microfluidic device. The system has been applied for the sensing of two different analyte types: biologically relevant phosphate anions and aromatic carboxylic acids, which are important for anthrax detecti

  11. Multilayer chitosan-based open tubular capillary anion exchange column with integrated monolithic capillary suppressor

    International Nuclear Information System (INIS)

    Highlights: ► Uses a multilayer chitosan–glutaraldehyde coating as anion exchanger. ► Uses a methacrylate-acrylic acid polymer monolith as suppressor. ► Demonstrates first integral suppressor open tubular anion chromatography. - Abstract: We describe a multilayered open tubular anion exchange column fabricated by alternately pumping solutions of chitosan and glutaraldehyde. The column is terminated in an integrally bonded monolithic suppressor cast around a mandrel of a tungsten wire, composed of an acrylic acid (AA)–ethylene dimethacrylate (EDMA) monolith that is made with sufficient porogen for the monolith to function as a membrane. For a 4.5 m long 75 μm bore column coated with 24 successive layers of the condensation polymer (estimated to contain ∼72 molecular layers) and coupled to 1 cm length of a suppressor fabricated with 55–60% AA, effective separation of several common anions (F−, Cl−, NO2−, Br−, NO3−, average number of theoretical plates ∼12,000) and adequate suppression of 1 mM KOH used as eluent was observed at a flow rate of 800 nL min−1 to obtain sub-picomol detection limits at an operating pressure of ∼1 bar. The separation is not time efficient but the system can be meritorious in unique niche applications where a small form factor is desired and liquid volume and power consumption are more important than separation speed.

  12. Cation- and anion-exchanges induce multiple distinct rearrangements within metallosupramolecular architectures.

    Science.gov (United States)

    Riddell, Imogen A; Ronson, Tanya K; Clegg, Jack K; Wood, Christopher S; Bilbeisi, Rana A; Nitschke, Jonathan R

    2014-07-01

    Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe(II) prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd12L18 prism and the Cd2L3 triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd12L18 structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd10L15 complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd10L15 complex and report solution state data for J-coupling through a CH···F(-) hydrogen bond indicating the strength of these interactions in solution.

  13. Anion effect on radiochemical stability of room-temperature ionic liquids under gamma irradiation

    International Nuclear Information System (INIS)

    Radiochemical stability of imidazolium-based ionic liquids constituted of the BuMeIm+ cation and associated with four commonly used anions (X-: Tf2N-, TfO-, PF6- and BF4-) has been investigated under gamma irradiation for high irradiation doses (up to 2.0 MGy). The anion effect has been examined by quantifying the radiolytic yields of disappearance for cation and anions and by identifying corresponding radiolysis products with several analytical techniques. On the one hand, a large number of radiolysis products are formed throughout the irradiation in ionic liquid solutions, resulting from reactions of primary generated species of cation and anion by indirect radiolysis. Primary generated species can react together throughout the irradiation by indirect radiolysis to form numerous radiolysis products in small quantities, indicating that several complex degradation pathways are involved for these radiation doses. This degradation pattern has been confirmed by identification of numerous gaseous radiolytic products. On the other hand, quantitative studies show that radiochemical stabilities of ionic liquids are in the same range of values as systems envisioned in nuclear fuel reprocessing with relatively low hydrogen yields. Indeed, this present work emphasizes the suitability of ionic liquids for applications in the nuclear fuel cycle. (authors)

  14. Hydrogen bond mediated stabilization of the salt bridge structure for the glycine dimer anion

    NARCIS (Netherlands)

    S. Heiles; R.J. Cooper; G. Berden; J. Oomens; E.R. Williams

    2015-01-01

    The formation of a salt bridge in deprotonated glycine dimer anions in a solvent-free environment is investigated using both infrared multiple photon dissociation spectroscopy between 600 and 1800 cm(-1) and theory. The zwitterionic and nonzwitterionic forms of glycine in this complex are computed t

  15. Precipitation of anionic nitrato complexes of Ce4+ and Pu4+ with cetylpyridinium nitrate

    International Nuclear Information System (INIS)

    Anionic nitrato complexes of Ce4+ and Pu4+ react with cetylpyridinium nitrate under formation of sparingly soluble salts. Depending on the pH, both metals are precipitated as hexanitrato complexes or octanitrato complexes or as the corresponding double salts. (Author)

  16. Superoxide Anion Radical Scavenging Ability of Quaternary Ammonium Salt of Chitosan

    Institute of Scientific and Technical Information of China (English)

    Xiao Yan ZHU; Jian Min WU; Zhi Shen JIA

    2004-01-01

    A series of N-alkyl or N-aryl chitosan quaternary ammonium salt were prepared using 96% deacetylated chitosan. Their scavenging activities against superoxide anion radical were investigated by chemiluminescence. The IC50 values of these compounds range from 280 to 880 μg/mL, which should be attributed to their different substitutes.

  17. Hexavalent chromium removal performance of anionic functionalized monolithic polymers: column adsorption, regeneration and modelling.

    Science.gov (United States)

    Barlik, Necla; Keskinler, Bülent; Kocakerim, M Muhtar

    2016-01-01

    Anionic functionalized monolithic macro-porous polymers were used for the removal of hexavalent chromium(VI) anions from aqueous solution in column experiments. At a flux of 1.0 cm min and 30 mg Cr(VI) L(-1) feed concentration, breakthrough capacity and apparent capacity were 0.066 g Cr(VI) g(-1) anionic monolith and 0.144 g Cr(VI) g(-1) anionic monolith, respectively. The degree of column utilization was found to lie in the range 41-46%. Two kinetic models, theoretical and Thomas models, were applied to experimental data to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The simulation of the whole breakthrough curve was effective with the models. At a flux of 1.0 cm min and 30 mg Cr(VI) L(-1) feed concentration, the dispersion coefficient and adsorption equilibrium constant (K) were 3.14 × 10(-7) m s(-1) and 3,840, respectively. Also, Thomas model parameters k1 (rate constant of adsorption) and qm (equilibrium solid-phase concentration of sorbed solute) were 1.08 × 10(-3) L mg(-1) min(-1) and 0.124 g g(-1), respectively. After reaching equilibrium adsorption capacity, the monoliths were regenerated using 1 N HCl and were subsequently re-tested. It was found that the regeneration efficiency reduced from 98% after second usage to 97% after the third usage. PMID:27003067

  18. A New Approach for Removing Anionic Organic Dyes from Wastewater Based on Electrostatically Driven Assembly.

    Science.gov (United States)

    Sansuk, Sira; Srijaranai, Somkiat; Srijaranai, Supalax

    2016-06-21

    A conceptually new approach for an efficient removal of anionic organic dyes from wastewater using layered double hydroxides (LDHs) through their formation is presented. Acid yellow 25 (AY25) was used as anionic organic dye model molecules. As a result of the electrostatic induction, the removal mechanism involved a concurrent incorporation of AY25 molecules into the interlayer of LDHs during their structural arrangement, where Mg(2+) and Al(3+) ions were utilized to construct the base of LDHs in an alkaline solution. It was found that the molar stoichiometry of all precursors was a key factor affecting the removal efficiency. Within 5 min removal time, this method still maintained high removal efficiency of over 97% and provided a removal capacity of ∼186 mg g(-1), comparable to that of other LDH-based methods. Also, almost complete dye recovery was simply achieved by anionic exchange with common anions (Cl(-), NO3(-), and CO3(2-)). Additionally, the present technique is straightforward, cost-effective, and environmentally friendly since it avoids the synthesis step of sorbents, thus significantly saving time, chemicals, and energy. Hence, this strategy not only exhibits the alternative exploitation of LDHs, but also provides new insights into the removal of contaminants from wastewater. PMID:27231753

  19. Anion-intercalated layered double hydroxides modified test strips for detection of heavy metal ions.

    Science.gov (United States)

    Wang, Nan; Sun, Jianchao; Fan, Hai; Ai, Shiyun

    2016-02-01

    In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)6(4-) or S(2-) anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10(-6) mol L(-1). Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields. PMID:26653453

  20. Polyspecific drug and steroid clearance by an organic anion transporter of mammalian liver

    NARCIS (Netherlands)

    Bossuyt, [No Value; Muller, M; Hagenbuch, B; Meier, PJ

    1996-01-01

    An organic anion-transporting polypeptide that mediates sodium-independent uptake of negatively charged sulfobromophthalein and bile salts has recently been cloned from rat liver (Jacquemin et al., 1994). In this study we have extended the substrate specificity studies to neutral and positively char

  1. Preparation and Characterization of Low Dispersity Anionic Multiresponsive Core-Shell Polymer Nanoparticles

    NARCIS (Netherlands)

    Pinheiro, J.P.; Moura, L.; Fokkink, R.G.; Farinha, J.P.S.

    2012-01-01

    We prepared anionic multistimuli responsive core-shell polymer nanoparticles with very low size dispersity. By using either acrylic acid (AA) or methacrylic acid (MA) as a comonomer in the poly(N-isopropyl acrylamide) (PNIPAM) shell, we are able to change the distribution of negative charges in the

  2. [Water-soluble anions of atmosphere on Tianwan nuclear power station].

    Science.gov (United States)

    Zhao, Heng-Qiang; He, Ying; Zheng, Xiao-Ling; Chen, Fa-Rong; Pang, Shi-Ping; Wang, Cai-Xia; Wang, Xiao-Ru

    2010-11-01

    Three major water-soluble anions (Cl-, SO4(2-) and NO3-) in the atmosphere of the Tianwan nuclear power station in Lianyungang were determined by ion chromatography from June 2005 to May 2006. The results showed that the annual average concentration of Cl-, SO4(2-) and NO3- in the atmosphere of Tianwan nuclear power station was (33.12 +/- 53.63) microg x m(-3), (53.34 +/- 30.34) microg x m(-3) and (8.34 +/- 4.47) microg x m(-3), respectively. The concentrations of the three water-soluble anions showed evident trend of seasonal variation. The concentrations of Cl-, SO4(2-) reached the highest level in summer and the lowest level in winter, while the concentration of NO3- in autumn and winter was higher than those in summer and spring. Meteorological parameters such as wind direction, wind speed, temperature and relative humidity were studied and showed definite influence to the anions concentration of the atmosphere. This is the first simultaneous monitoring of corrosive anions in the atmosphere of Chinese coastal nuclear power plant, and it will provide basis for the prevention of marine atmospheric corrosion, which will ensure the safely operating of our nuclear power industry. PMID:21250433

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

    Science.gov (United States)

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

    2015-03-01

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

  4. Study of the emission oxidative reactions of ruthenium (II) complex by cationic compounds in anionic micelles

    International Nuclear Information System (INIS)

    The oxidative quenching of the emission of the tetraanionic complex tris (4,4' dicarboxylate - 2,2' - bipyridine ruthenium (II) in aqueous solution, by both organic and inorganic compounds in presence of anionic detergents, above and below the critical micelle concentration is studied. The organic cations, the inorganic ion and detergents used are shown. (M.J.C.)

  5. The analysis of cations and anions in illicit heroin using capillary electrophoresis with indirect UV detection.

    Science.gov (United States)

    Lurie, I S

    1996-01-01

    Methodology is presented for the analysis of cations and anions in illicit heroin using CE with indirect UV detection. The cations investigated include ammonium, calcium, potassium, magnesium, and sodium; the anions included acetate, chloride, citrate, phosphate, sulfate, and tartrate. For cations, the Ion Phor run buffer (Dionex Corp., Sunnyvale, CA, U.S.A.) consisting of 4 mM copper sulfate, 4 mM formic acid, and 3 mM 18-crown-6 (pH 3.0) was used. For anions, proprietary reagents were used, including the Anitron run buffer (PE Applied Biosystems, Foster City, CA, U.S.A.) and Micro-Coat capillary charge-reversal agent (PE Applied Biosystems), which was utilized to flush the capillary prior to each analysis. Lithium nitrate was used as an internal standard; excellent long- and short-term precision in relative retention times were obtained for both cations and anions. The short-term precision in peak areas was satisfactory. For the various ions examined, a linearity range of a little less than two orders of magnitude was observed. The methodology is capable of analyzing ions down to the 10(-3)% level relative to heroin.

  6. Metabolism and root exudation of organic acid anions under aluminium stress

    NARCIS (Netherlands)

    Mariano, E.D.; Jorge, R.A.; Keltjens, W.G.; Menossi, M.

    2005-01-01

    Numerous plant species can release organic acid anions (OA) from their roots in response to toxic aluminium (Al) ions present in the rooting medium. Hypothetically OA complex Al in the root apoplast and/or rhizosphere and thus avoid its interaction with root cellular components and its entry in the

  7. ZEOLITE PERFORMANCE AS AN ANION EXCHANGER FOR ARSENIC SEQUESTRATION IN WATER

    Science.gov (United States)

    Zeolites are well known for their use in ion exchange and acid catalysis reactions. The use of zeolites in anion or ligand exchange reactions is less studied. The NH4+ form of zeolite Y (NY6, Faujasite) has been tested in this work to evaluate its performance for arsenic removal...

  8. How Phosphorylation and ATPase Activity Regulate Anion Flux though the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR).

    Science.gov (United States)

    Zwick, Matthias; Esposito, Cinzia; Hellstern, Manuel; Seelig, Anna

    2016-07-01

    The cystic fibrosis transmembrane conductance regulator (CFTR, ABCC7), mutations of which cause cystic fibrosis, belongs to the ATP-binding cassette (ABC) transporter family and works as a channel for small anions, such as chloride and bicarbonate. Anion channel activity is known to depend on phosphorylation by cAMP-dependent protein kinase A (PKA) and CFTR-ATPase activity. Whereas anion channel activity has been extensively investigated, phosphorylation and CFTR-ATPase activity are still poorly understood. Here, we show that the two processes can be measured in a label-free and non-invasive manner in real time in live cells, stably transfected with CFTR. This study reveals three key findings. (i) The major contribution (≥90%) to the total CFTR-related ATP hydrolysis rate is due to phosphorylation by PKA and the minor contribution (≤10%) to CFTR-ATPase activity. (ii) The mutant CFTR-E1371S that is still conductive, but defective in ATP hydrolysis, is not phosphorylated, suggesting that phosphorylation requires a functional nucleotide binding domain and occurs in the post-hydrolysis transition state. (iii) CFTR-ATPase activity is inversely related to CFTR anion flux. The present data are consistent with a model in which CFTR is in a closed conformation with two ATPs bound. The open conformation is induced by ATP hydrolysis and corresponds to the post-hydrolysis transition state that is stabilized by phosphorylation and binding of chloride channel potentiators. PMID:27226582

  9. Anion recognition ability of a novel azo dye derived from 4-hydroxycoumarin

    Energy Technology Data Exchange (ETDEWEB)

    Chandel, Madhurya; Roy, Sutapa Mondal; Sharma, Darshna [Department of Applied Chemistry, SV National Institute of Technology, Surat, Gujarat (India); Sahoo, Suban K., E-mail: suban_sahoo@rediffmail.com [Department of Applied Chemistry, SV National Institute of Technology, Surat, Gujarat (India); Patel, Amit; Kumari, Premlata [Department of Applied Chemistry, SV National Institute of Technology, Surat, Gujarat (India); Dhale, Ranu S. [School of Chemical Sciences, National Institute of Science Education and Research, Bhubaneswar, Odisha (India); Ashok, Kumar S.K. [School of Advanced Sciences, VIT University, Vellore, Tamil Nadu (India); Nandre, Jitendra P.; Patil, Umesh D. [School of Chemical Sciences, North Maharashtra University, Jalgaon, Maharashtra (India)

    2014-10-15

    The anion recognition ability of a novel azo dye derived from 4-hydroxycuomarin (L) was investigated by experimental (UV–vis, fluorescence and {sup 1}H NMR) and theoretical [(B3LYP/6-31G(d,p)] methods. Among the surveyed anions, the receptor L showed both naked-eye detectable color and spectral changes in the presence of F{sup −}, AcO{sup −} and H{sub 2}PO{sub 4}{sup −} due to the formation of hydrogen bonding complexes followed by deprotonation between these anions and L. - Highlights: • Anion recognition ability of an easy-to-prepare coumarin derivative L was reported. • L showed both naked-eye and spectral responses towards AcO{sup −}, F{sup −} and H{sub 2}PO{sub 4}{sup −}. • Deprotonation mechanism was proposed for the observed spectral responses. • L showed selective ratiometric fluorescence ‘turn-on’ responses towards AcO{sup −} and F{sup −}.

  10. Spectroscopic Evidence for an Oxazolone Structure in Anionic b-Type Peptide Fragments

    NARCIS (Netherlands)

    Grzetic, J.; Oomens, J.

    2012-01-01

    Infrared spectra of anionic b-type fragments generated by collision induced dissociation (CID) from deprotonated peptides are reported. Spectra of the b(2) fragments of deprotonated AlaAlaAla and AlaTyrAla have been recorded over the 800-1800 cm(-1) spectral range by multiple-photon dissociation (MP

  11. Spectroscopic evidence for an oxazolone structure in anionic b-type peptide fragments

    NARCIS (Netherlands)

    J. Grzetic; J. Oomens

    2012-01-01

    Infrared spectra of anionic b-type fragments generated by collision induced dissociation (CID) from deprotonated peptides are reported. Spectra of the b2 fragments of deprotonated AlaAlaAla and AlaTyrAla have been recorded over the 800-1800 cm-1 spectral range by multiple-photon dissociation (MPD) s

  12. Regioselective synthesis of heteroaryl triflones by LDA (lithium diisopropylamide)-mediated anionic thia-Fries rearrangement.

    Science.gov (United States)

    Xu, Xiu-Hua; Wang, Xin; Liu, Guo-kai; Tokunaga, Etsuko; Shibata, Norio

    2012-05-18

    Novel heteroaryl triflones including oxindole, pyrazolone, pyridine, and quinoline derivatives have been regioselectively synthesized by LDA-mediated thia-Fries rearrangement for the first time. These reactions are also the first examples of the application of anionic thia-Fries rearrangement in heteroaromatic compounds.

  13. Theoretical and Experimental Studies on Interactions of Cationic-Anionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    王大喜; 杜永顺; 岳长涛; 侯建国; 栗秀刚; 杨文杰

    2003-01-01

    Typical cationic and anionic surfactants were chosen and their interactions were calculated by quantum chemical method. Interaction energies are -0.2378 kJ·mol-1, -3.3394 kJ·mol-1 and 0.1204 kJ·mol-1 for the molecular pairs with fluocarbon and hydrocarbon chain: C4H10/C5H12, C4F10/C5H12, and C4F10 /C5F12, respectively.When hydrophilic group with cationic and anionicions is introduced, interaction energies are -287.40kJ·mol-1,-311.18 kJ·mo1-1 and -345.83 kJ·mo1-1. The results show that there is strong static interaction between cationic and anionic surfactants. It has been predicted that mixed monolayer may be formed and surface activity is enhanced favorably, especially for mixtures of cationic and anionic surfactants with fluocarbon and hydrocarbon chains. The anionic surfactants, sodium octadecylbenzenesulfonate perfluopolyetherbenzenesulonate(ANF-I) was synthesized, mixture effects of ANF-I with sodium octadecylbenzenesulfonate or dodecyldimethyl benzylammonium bromide were studied. The results indicate that the efficiency of mixing increased and the theoretical prediction was testified. These results can provide useful information for the design of new surfactants.

  14. Selective Interaction of a Cationic Polyfluorene with Model Lipid Membranes: Anionic versus Zwitterionic Lipids

    Directory of Open Access Journals (Sweden)

    Zehra Kahveci

    2014-03-01

    Full Text Available This paper explores the interaction mechanism between the conjugated polyelectrolyte {[9,9-bis(6'-N,N,N-trimethylammoniumhexyl]fluorene-phenylene}bromide (HTMA-PFP and model lipid membranes. The study was carried out using different biophysical techniques, mainly fluorescence spectroscopy and microscopy. Results show that despite the preferential interaction of HTMA-PFP with anionic lipids, HTMA-PFP shows affinity for zwitterionic lipids; although the interaction mechanism is different as well as HTMA-PFP’s final membrane location. Whilst the polyelectrolyte is embedded within the lipid bilayer in the anionic membrane, it remains close to the surface, forming aggregates that are sensitive to the physical state of the lipid bilayer in the zwitterionic system. The different interaction mechanism is reflected in the polyelectrolyte fluorescence spectrum, since the maximum shifts to longer wavelengths in the zwitterionic system. The intrinsic fluorescence of HTMA-PFP was used to visualize the interaction between polymer and vesicles via fluorescence microscopy, thanks to its high quantum yield and photostability. This technique allows the selectivity of the polyelectrolyte and higher affinity for anionic membranes to be observed. The results confirmed the appropriateness of using HTMA-PFP as a membrane fluorescent marker and suggest that, given its different behaviour towards anionic and zwitterionic membranes, HTMA-PFP could be used for selective recognition and imaging of bacteria over mammalian cells.

  15. Separation of the rare earths by anion-exchange in the presence of lactic acid

    Science.gov (United States)

    Faris, J. P.

    1969-01-01

    Investigation of adsorption of rare earths and a few other elements to an anion-exchange resin from mixed solvents containing lactic acid shows that the lanthanides are absorbed more strongly than from the alpha-hydroxyisobutryric acid system, but with less separation between adjacent members of the series.

  16. Valence and diffuse-bound anions of noble-gas complexes with uracil

    Science.gov (United States)

    Streit, Lívia; Dolgounitcheva, O.; Zakrzewski, V. G.; Ortiz, J. V.

    2012-11-01

    Valence-bound (VB) and diffuse-bound (DB) anions of noble-gas (Ar, Kr, and Xe) complexes with uracil have been studied with ab initio methods. MP2 optimizations revealed minima corresponding to anions of both kinds in each case. Coupled-cluster singles and doubles with perturbative triples, CCSD(T), and electron propagator single-point calculations were performed in order to assess vertical and adiabatic electron detachment energies of these complexes. Ab initio electron propagator calculations employed the outer valence Green's function and partial third-order approximations, and the algebraic diagrammatic construction in third order. Basis set effects have been systematically examined. DB anions of all three complexes were adiabatically bound, with calculated adiabatic electron attachment energies below 0.06 eV. Corresponding vertical electron detachment energies were below 0.1 eV. As to VB anions, only the Xe complex had a positive adiabatic electron detachment energy, of 0.01 eV, with a corresponding vertical electron detachment energy of 0.6 eV. These computational findings are consistent with the interpretation of results previously obtained experimentally by Hendricks et al.

  17. Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M. Frederick; Jalisatgi, Satish S.; Safronov, Alexander V.; Lee, Han Beak; Wu, Jianguo

    2010-10-01

    Phase 1. Hydrolysis of borohydride compounds offer the potential for significant hydrogen storage capacity, but most work to date has focused on one particular anion, BH4-, which requires high pH for stability. Other borohydride compounds, in particular polyhedral borane anions offer comparable hydrogen storage capacity without requiring high pH media and their long term thermal and hydrolytic stability coupled with non-toxic nature make them a very attractive alternative to NaBH4. The University of Missouri project provided the overall program focal point for the investigation of catalytic hydrolysis of polyhedral borane anions for hydrogen release. Due to their inherent stability, a transition metal catalyst was necessary for the hydrolysis of polyhedral borane anions. Transition metal ions such as cobalt, nickel, palladium and rhodium were investigated for their catalytic activity in the hydrolysis of nido-KB11H14, closo-K2B10H10, and closo-K2B12H12. The rate of hydrolysis follows first-order kinetics with respect to the concentration of the polyhedral borane anion and surface area of the rhodium catalyst. The rate of hydrolysis depends upon a) choice of polyhedral borane anion, c) concentration of polyhedral borane anion, d) surface area of the rhodium catalyst and e) temperature of the reaction. In all cases the yield of hydrogen was 100% which corresponds to ~7 wt% of hydrogen (based on material wt%). Phase 2. The phase 2 of program at the University of Missouri was focused upon developing aluminum ammonia-boranes (Al-AB) as chemical hydrogen storage materials, specifically their synthesis and studies of their dehydrogenation. The ammonia borane molecule (AB) is a demonstrated source of chemically stored hydrogen (19.6 wt%) which meets DOE performance parameters except for its regeneration from spent AB and elemental hydrogen. The presence of an aluminum center bonded to multiple AB residues might combine the efficiency of AB dehydrogenation with an aluminum

  18. Anion retention in soil: Possible application to reduce migration of buried technetium and iodine

    Energy Technology Data Exchange (ETDEWEB)

    Gu, B.; Schulz, R.K. (California Univ., Berkeley, CA (United States). Dept. of Soil Science)

    1991-10-01

    This report summarizes a literature review of our present knowledge of the anion exchange properties of a number of soils and minerals, which may potentially be used as anion exchangers to retard migration of such anions as iodide (I{sup {minus}}), iodate (IO{sub 3}{sup {minus}}) and pertechnetate (TcO{sub 4}{sup {minus}}) away from disposal site. The amorphous clays allophane and imogolite, are found to be among the most important soil components capable of developing appreciable amounts of positive charge for anion exchange even at about neutral pH. Decreases in the SiO{sub 2}/Al{sub 2}O{sub 3} ratio and soil pH result in an increase in soil AEC. Allophane and imogolite rich soils have an AEC ranging from 1 to 18 meq/100g at pH about 6. Highly weathered soils dominated by Fe and Al oxides and kaolinite may develop a significant amount of AEC as soil pH falls. The retention of iodine (I) and technetium ({Tc}), by soils is associated with both soil organic matter, and Fe and Al oxides, whereas sorption on layer silicate minerals in negligible. Fe and Al oxides become more important in the retention of anionic I{sup {minus}}, IO{sub 3}{sup {minus}}, and TcO{sub 4}{sup {minus}} as pH falls, since more positive charge is developed on the oxide surfaces. Although few studies, if any, have been conducted on I and {Tc} sorption by soil allophane and imogolite, it is estimated that a surface plough soil (2 million pounds soil per acre) with 5 meq/100g AEC, as is commonly found in andisols, shall retain approximately 5900 kg I and 4500 kg {Tc}. It is conceivable that an anion exchanger such as an andisol could be used to modify the near field environment of a radioactive waste disposal facility. This whole disposal system would then offer similar migration resistance to anions as is normally afforded to cations by usual and normal soils. 93 refs., 10 figs., 7 tabs.

  19. Effects on anionic salts in a pre-partum dairy ration on calcium metabolism

    Directory of Open Access Journals (Sweden)

    C.J. Van Dijk

    2001-07-01

    Full Text Available The effects of anionic salts in the transition diet on serum and urine calcium at calving and on peripartal health, subsequent milk production and fertility performance were studied in a well-managed, high-producing Friesland dairy herd. Over a period of a year, approximately 21 days before the expected date of calving, 28 pre-partum heifers and 44 multiparous dry cows were randomly allocated within parity to 1 of 2 transition diets, designated control and experimental anionic diets. The anionic diet contained the same quantities of the basic transition ration fed to the control group as well as a standard anionic salt mixture containing 118 g NH4Cl, 36 g (NH42SO4 and 68 g MgSO4 (total 222 g per animal per day. This reduced the DCAD to -11.68 mEq/100 g dietary dry matter compared to +13.57 for the control diet. Blood and urine were randomly sampled from 7 to 8 animals within each category within 3 hours post-partum. Serum calcium (total and ionised and creatinine, urine calcium and creatinine and the fractional clearance of calcium were assessed. Relevant clinical, milk production, and fertility data were collected. The total serum calcium (2.07 versus 1.60 mmol/ , serum ionised calcium (1.12 vs 1.02 mmol/ , urine calcium (0.92 vs 0.10 mmol/ and the fractional clearance of calcium (1.88 vs 0.09 % were significantly higher (P <0.01 at calving for multiparous cows fed the anionic diet compared to those fed the control diet. In the primiparous cows there were no significant differences in serumcalcium levels. However, the urine calcium (1.07 vs 0.43 mmol/ and the fractional clearance of calcium was higher (1.75 vs 0.45 % in cows fed the anionic diet (P <0.05 and 0.01 respectively. These results illustrated that there were benefits, although no differences were demonstrated with respect to health, milk production or fertility. The supplementation of diets with anionic salts in the last 2-3 weeks before calving has the potential to significantly

  20. Anion coordination complex [ClPt(bpt)4]Cl (bpt= N,N’-bis(3-pyridylmethyl)-2-thiourea)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The anion coordination complex,[ClPt(bpt)4]Cl (bpt=N,N’-bis(3-pyridylmethyl)-2-thiourea),was synthesized and studied by X-ray crystal structure analysis,NMR and FAB mass spectra. In the solid state,the Pt(bpt)4 anion receptor adopts a cone conformation to bind the chloride anion through hydrogen bonds and electrostatic interaction in which the four branches of the thiourea ligands bind the chloride anion to form N-H…Cl-hydrogen bonds (3.49-3.81). The entraped chloride anion is situated above the Pt(Ⅱ) center at 3.52 . Further second-sphere coordination assemby from the Pt(bpt)4 core with 8 zinc(Ⅱ) tetraphenylporphyrins (ZnPr) is discussed.

  1. Denture polymers with antimicrobial properties: a review of the development and current status of anionic poly(methyl methacrylate) polymers.

    Science.gov (United States)

    Raj, Periathamby Antony; Dentino, Andrew R

    2013-09-01

    The denture base polymer poly(methyl methacrylate) (PMMA) is highly susceptible for microbial colonization resulting in denture-associated infections. Over the years research has focused on ways to modify the PMMA properties via surface and chemical modification. These studies led to the development of new denture polymers that include anionic PMMA polymers. The new anionic polymers presented the possibility of compromising the physical and mechanical properties required for denture fabrication. These obstacles were overcome by generating anionic PMMA polymers with physical and mechanical properties suitable for denture fabrication. A large body of literature is available on the anionic PMMA polymers, their antimicrobial properties and their potential for the commercial and clinical application as dental biomaterials. This article describes a review and evaluation of the anionic PMMA polymers for their suitability to serve as denture base polymers, their antimicrobial properties, their efficacy to prevent denture-induced infection and their safety in the oral environment.

  2. Fluorescent sensing of anions based on excited state intramolecular proton transfer in N-(3-hydroxy-2-naphthamido)-N'-phenylthiourea

    Institute of Scientific and Technical Information of China (English)

    LI Zhao; CHEN YaoHan; JIANG YunBao

    2009-01-01

    A neutral N-amidothiourea-based excited state Intramolecular proton transfer (ESlPT) anion receptor bearing an o-hydroxynaphthamide fluorophore and a thiourea binding site, N-(3-hydroxy-2-naph-thamide)-N'-phenylthiourea (1a), was designed and synthesized. Fluorescence and absorption re-sponse of 1a toward anions were assessed in acetonitrile. IR and NMR experiments indicated that the short-wavelength normal emission other than ESIPT fluorescence. Due to the high anion binding affin-ity of the N-amidothiourea binding site and the formation of a hydrogen binding network in the 1a-anion leading to the ESlPT and the observation of the long-wavelength ESIPT emission whereas the normal fluorescence is quenched. On the basis of NMR and fluorescence titrations and control experiments with model compounds, a sensing mechanism of the anion-binding-induced ESIPT was proposed.

  3. Effects of Electrolyte Anions and pH on Adsortpion of Sulfate by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGGANGYA; G.M.BRUEMMER; 等

    1996-01-01

    The effects of three electrolyte anions,ionic strength and pH on the adsorption of sulfate by two variable charge soils,with different surface charge properties were studied.Under the conditions of the same pH and ionic strength the effect of electrolyte anions on the adsorption of sulfate was in the order of Cl->NO3->ClO4-,indicating the difference of the nature among these three anions.For ferralsol in the same concentration of chloride and perchloride solutions,the two sulfate adsorption-pH curves could intersect at certain pH value.When pH was higher than the intersecting point.more sulfate was adsorbed in the perchloride solution,while when it was lower than the intersecting point,more sulfate was adsorbed in the chloride solution.In different concentratioins of electrolyte solution,the curves of the amount of oxy-acid anion adsorbed,which changed with pH,could intersect at a certain pH,which is termed point of zero salt effect(PZSE) on adsortpion.The nature of electrolyte anions influenced obviously the appearace of PZSE for sulfate adsorption.For ferralsol the curves of adsorption converged to about pH 7 in NaCl solution seemed to intersect in NaNO3 solution and to have a typical PZSE for sulfate adsorption in NaClO4 solution,For Acrisol the three curves of adsorption were nearly parallel in NaCl and NaNO3 solutions and converged to pH 6.5 in NaClO4 solution.

  4. Detection of Perchlorate Anion on Functionalized Silver Colloids Using Surface-Enhanced Raman Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Tio, J.; Wang, W.; Gu, B.

    2005-01-01

    Perchlorate anion interferes with the uptake of iodide by the human thyroid gland and consequently disrupts the regulation of metabolism. Chronic exposure to high levels of perchlorate may lead to the formation of thyroid gland tumors. Although the Environmental Protection Agency (EPA) has not set a maximum contaminant level (MCL) for perchlorate, a draft drinking water range of 4-18 ppb based on 2 liter daily consumption of water has been established. The current EPA approved method for detecting perchlorate uses ion chromatography which has a detection limit of ~1ppb and involves lengthy analytical time in the laboratory. A unique combination of the surface-enhanced Raman scattering (SERS) effect and the bifunctional anion exchange resin’s high selectivity may provide an alternative way to detect perchlorate at such low concentrations and with high specificity. SERS, which uses laser excitation of adsorbed perchlorate anions on silver nanoparticles, has been shown to detect perchlorate anions at concentrations as low as 50 ppb. Normal micro-Raman analysis of perchlorate sorbed onto the resin beads has detected an even lower concentration of 10 ppb. In an effort to integrate these two effects, silver nanoparticles were coated with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride, a functional group similar to that found on the resin bead, and subsequently inserted into different perchlorate concentration environments. This method has resulted in perchlorate detection down to ~10 ppb and a more consistent detection of perchlorate anion at ~50 ppb than that of earlier methods. As suggested by the direct insertion of functionalized silver colloids into perchlorate samples, this technique may potentially allow for the development of a probe using on-site Raman spectrometry to detect significantly low concentrations of perchlorate in situ rather than in the laboratory.

  5. Performance of selected anion exchange resins for the treatment of a high DOC content surface water.

    Science.gov (United States)

    Humbert, Hugues; Gallard, Hervé; Suty, Hervé; Croué, Jean-Philippe

    2005-05-01

    The objective of this study was first to compare the performance of four strong anion exchange resins (AERs) (MIEX from Orica Pty Ltd, DOWEX-11 and DOWEX-MSA from DOW chemical and IRA-938 from Rohm and Haas) for their application in drinking water treatment (natural organic matter (NOM), mineral anions (nitrate, sulfate and bromide) and pesticide removal) using bench-scale experimental procedures on a high DOC content surface water. The efficiency of MIEX for NOM and mineral anions removal was furthermore evaluated using bench-scale dose-response experiments on raw, clarified and post-ozonated waters. NOM removal was assessed using the measurement of dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254) and the use of high-performance size exclusion chromatography with UV (HPSEC/UV) and fluorescence detection (HPSEC/FLUO). The MIEX and IRA938 anionic resins exhibit a faster removal of NOM and mineral anions compared to the DOWEX11 and MSA AERs. All the resins were found to be very effective with similar performances after 30 to 45 min of contact time. As expected, only limited sorption of atrazine and isoproturon (C0=1 microg/L) occurred with MIEX, DOWEX11 and MSA AERs. MIEX resin proved to be very efficient in eliminating NOM of high-molecular weight but also a large part of the smallest UV absorbing organic compounds which were refractory to coagulation/flocculation treatment. Remaining DOC levels after 30 min of contact with MIEX were found similar in raw water, clarified water and even post-ozonated water implying no DOC benefit can be gained by employing conventional treatment prior to MIEX treatment. Removal of bromide (initial concentration 110 microg/L) was also observed and ranged from 30% to 65% for resin dose increasing from 2 to 8 mL/L. T PMID:15899268

  6. Production of the carbonate radical anion during xanthine oxidase turnover in the presence of bicarbonate.

    Science.gov (United States)

    Bonini, Marcelo G; Miyamoto, Sayuri; Di Mascio, Paolo; Augusto, Ohara

    2004-12-10

    Xanthine oxidase is generally recognized as a key enzyme in purine catabolism, but its structural complexity, low substrate specificity, and specialized tissue distribution suggest other functions that remain to be fully identified. The potential of xanthine oxidase to generate superoxide radical anion, hydrogen peroxide, and peroxynitrite has been extensively explored in pathophysiological contexts. Here we demonstrate that xanthine oxidase turnover at physiological pH produces a strong one-electron oxidant, the carbonate radical anion. The radical was shown to be produced from acetaldehyde oxidation by xanthine oxidase in the presence of catalase and bicarbonate on the basis of several lines of evidence such as oxidation of both dihydrorhodamine 123 and 5,5-dimethyl-1-pyrroline-N-oxide and chemiluminescence and isotope labeling/mass spectrometry studies. In the case of xanthine oxidase acting upon xanthine and hypoxanthine as substrates, carbonate radical anion production was also evidenced by the oxidation of 5,5-dimethyl-1-pyrroline-N-oxide and of dihydrorhodamine 123 in the presence of uricase. The results indicated that Fenton chemistry occurring in the bulk solution is not necessary for carbonate radical anion production. Under the conditions employed, the radical was likely to be produced at the enzyme active site by reduction of a peroxymonocarbonate intermediate whose formation and reduction is facilitated by the many xanthine oxidase redox centers. In addition to indicating that the carbonate radical anion may be an important mediator of the pathophysiological effects of xanthine oxidase, the results emphasize the potential of the bicarbonate-carbon dioxide pair as a source of biological oxidants. PMID:15448145

  7. Anion and cation dynamics of sulfonylamide-based ionic liquids and the solid-liquid transitions.

    Science.gov (United States)

    Imanari, Mamoru; Fujii, Kozo; Mukai, Tomohiro; Mizushima, Noriko; Seki, Hiroko; Nishikawa, Keiko

    2015-04-14

    Some of the important factors that characterise room-temperature ionic liquids (RTILs) are the variety of conformations adopted by the constituent ions and their flexibility. Using 1,3-dimethylimidazolium bis(fluorosulfonyl)amide ([C1mim][FSA]) and 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)amide ([C1mim][NTf2]) as samples, the longitudinal and transverse relaxation times (T1 and T2) for (19)F and (1)H were determined as a function of temperature and were correlated with the dynamics of the phase behaviours of the two RTILs. Because the anions and cations in the two compounds have (19)F and (1)H nuclei, respectively, their dynamics can be independently investigated and the relationships between them can be discussed. For [C1mim][FSA], the only observed phase changes included melting and crystallisation. The temperature dependences of T1 and T2 for (19)F were similar to those of T1 and T2 for (1)H, indicating similar dynamics due to the formation of strong anion-cation interactions. For [C1mim][NTf2], the T1 and T2 values for both (19)F and (1)H discontinuously changed at same temperatures, which were assigned to the crystallisation and melting points. However, the T1 curves for (19)F and (1)H were different in the crystalline region, suggesting independent dynamics for the anions and cations in [C1mim][NTf2]. In the crystalline state for each salt, the cation dynamics was distinctly separated into the framework movement of the imidazolium ring and the movement of the methyl groups, while the anion dynamics was characterised by the movement of the entire anion. The influence of the crystal structure on the dynamics of each salt was also considered. PMID:25738430

  8. Absence of transepithelial anion exchange by rabbit OMCD: Evidence against reversal of cell polarity

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Matsuhiko; Schuster, V.L.; Stokes, J.B. (Univ. of Iowa College of Medicine, Iowa City (USA))

    1988-08-01

    In the rabbit cortical collecting duct (CCD), Cl tracer crosses the epithelium predominantly via an anion exchange system that operates in either a Cl-Cl or Cl-HCO{sub 3} exchange mode. In the present study, the authors used the {sup 36}Cl lumen-to-bath rate coefficient (K{sub Cl}, nm/s), a sensitive measurement of CCD transepithelial anion transport, to investigate the nature of Cl transport in the medullary collecting duct dissected from inner stripe, outer medulla (OMCD). The K{sub Cl} in OMCD perfused and bathed in HCO{sub 3}-Ringer solution was low and similar to that value observed in the CCD when anion exchange is inhibited and Cl permeates the epithelium by diffusion. To test the hypothesis that metabolic alkalosis could reverse the polarity of intercalated cells and thus induce an apical Cl-HCO{sub 3} exchanger in H{sup +}-secreting OMCD cells, they measured K{sub Cl} in OMCD from rabbits make alkalotic by deoxycorticosterone and furosemide. Although the base-line K{sub Cl} was slightly higher than in OMCD from control rabbits, the value was still far lower than the K{sub Cl} under comparable conditions in CCD. They conclude (1) Cl transport across the MCD by anion exchange is immeasurably low or nonexistent; (2) unlike the CCD, Cl transport in OMCD is not responsive to cAMP; and (3) metabolic alkalosis does not induce an apical anion exchanger in OMCD, i.e., does not cause epithelial polarity reversal.

  9. ON THE UBIQUITY OF MOLECULAR ANIONS IN THE DENSE INTERSTELLAR MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Cordiner, M. A.; Wirstroem, E. S.; Charnley, S. B. [Astrochemistry Laboratory and The Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Code 691, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Buckle, J. V. [Cavendish Astrophysics Group and Kavli Institute for Cosmology, Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Olofsson, A. O. H., E-mail: martin.cordiner@nasa.gov [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala (Sweden)

    2013-06-10

    Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C{sub 6}H{sup -} is detected in all seven target sources, including four sources where no anions have been previously detected: L1172, L1389, L1495B, and TMC-1C. The C{sub 6}H{sup -}/C{sub 6}H column density ratio is {approx}> 1.0% in every source, with a mean value of 3.0% (and standard deviation 0.92%). Combined with previous detections, our results show that anions are ubiquitous in dense clouds wherever C{sub 6}H is present. The C{sub 6}H{sup -}/C{sub 6}H ratio is found to show a positive correlation with molecular hydrogen number density, and with the apparent age of the cloud. We also report the first detection of C{sub 4}H{sup -} in TMC-1 (at 4.8{sigma} confidence), and derive an anion-to-neutral ratio C{sub 4}H{sup -}/C{sub 4}H =(1.2 {+-} 0.4) Multiplication-Sign 10{sup -5}(= 0.0012% {+-} 0.0004%). Such a low value compared with C{sub 6}H{sup -} highlights the need for a revised radiative electron attachment rate for C{sub 4}H. Chemical model calculations show that the observed C{sub 4}H{sup -} could be produced as a result of reactions of oxygen atoms with C{sub 5}H{sup -} and C{sub 6}H{sup -}.

  10. Calculation of electron affinities of polycyclic aromatic hydrocarbons and solvation energies of their radical anion.

    Science.gov (United States)

    Betowski, Leon D; Enlow, Mark; Riddick, Lee; Aue, Donald H

    2006-11-30

    Electron affinities (EAs) and free energies for electron attachment (DeltaGo(a,298K)) have been directly calculated for 45 polynuclear aromatic hydrocarbons (PAHs) and related molecules by a variety of theoretical methods, with standard regression errors of about 0.07 eV (mean unsigned error = 0.05 eV) at the B3LYP/6-31 + G(d,p) level and larger errors with HF or MP2 methods or using Koopmans' Theorem. Comparison of gas-phase free energies with solution-phase reduction potentials provides a measure of solvation energy differences between the radical anion and neutral PAH. A simple Born-charging model approximates the solvation effects on the radical anions, leading to a good correlation with experimental solvation energy differences. This is used to estimate unknown or questionable EAs from reduction potentials. Two independent methods are used to predict DeltaGo(a,298K) values: (1) based upon DFT methods, or (2) based upon reduction potentials and the Born model. They suggest reassignments or a resolution of conflicting experimental EAs for nearly one-half (17 of 38) of the PAH molecules for which experimental EAs have been reported. For the antiaromatic molecules, 1,3,5-tri-tert-butylpentalene and the dithia-substituted cyclobutadiene 1, the reduction potentials lead to estimated EAs close to those expected from DFT calculations and provide a basis for the prediction of the EAs and reduction potentials of pentalene and cyclobutadiene. The Born model has been used to relate the electrostatic solvation energies of PAH and hydrocarbon radical anions, and spherical halide anions, alkali metal cations, and ammonium ions to effective ionic radii from DFT electron-density envelopes. The Born model used for PAHs has been successfully extended here to quantitatively explain the solvation energy of the C60 radical anion.

  11. Increased anion channel activity is an unavoidable event in ozone-induced programmed cell death.

    Directory of Open Access Journals (Sweden)

    Takashi Kadono

    Full Text Available BACKGROUND: Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. PRINCIPAL FINDINGS: By exposing cells to a strong pulse of ozonized air, an acute cell death was observed in suspension cells of Arabidopsis thaliana used as a model. We demonstrated that O(3 treatment induced the activation of a plasma membrane anion channel that is an early prerequisite of O(3-induced cell death in A. thaliana. Our data further suggest interplay of anion channel activation with well known plant responses to O(3, Ca(2+ influx and NADPH-oxidase generated reactive oxygen species (ROS in mediating the oxidative cell death. This interplay might be fuelled by several mechanisms in addition to the direct ROS generation by O(3; namely, H(2O(2 generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death. SIGNIFICANCE: Collectively, our data indicate that anion efflux is an early key component of morphological and biochemical events leading to O(3-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation.

  12. Dowex anion exchanger-loaded-baker's yeast as bi-functionalized biosorbents for selective extraction of anionic and cationic mercury(II) species

    International Nuclear Information System (INIS)

    Dowex anion exchanger-immobilized-baker's yeast [Dae-yeast] were synthesized and potentially applied as environmental friendly biosorbents to evaluate the up-take process of anionic and cationic mercury(II) species as well as other metal ions. Optimization of mass ratio of Dowex anion exchanger versus yeast (1:1-1:10) in presence of various interacting buffer solutions (pH 4.0-9.0) was performed and evaluated. Surface modification of [Dae-yeast] was characterized by scanning electron microscopy (SEM) and infrared spectroscopy. The maximum metal biosorption capacity values of [Dae-yeast] towards mercury(II) were found in the range of 0.800-0.960, 0.840-0.950 and 0.730-0.900 mmol g-1 in presence of buffer solutions pH 2.0, 4.0 and 7.0, respectively. Three possible and different mechanisms are proposed to account for the biosorption of mercury and mercuric species under these three buffering conditions based on ion exchange, ion pair and chelation interaction processes. Factors affecting biosorption of mercury from aqueous medium including the pH effect of aqueous solutions (1.0-7.0), shaking time (1-30 min) and interfering ions were searched. The potential applications of modified biosorbents for selective biosorption and extraction of mercury from different real matrices including dental filling waste materials, industrial waste water samples and mercury lamp waste materials were also explored. The results denote to excellent percentage extraction values, from nitric acid as the dissolution solvent with a pH 2.0, as determined in the range of 90.77-97.91 ± 3.00-5.00%, 90.00-93.40 ± 4.00-5.00% and 92.31-100.00 ± 3.00-4.00% for the three tested samples, respectively.

  13. The perchlorate anion is more effective than the trifluoroacetate anion as an ion-pairing reagent for reversed-phase chromatography of peptides

    OpenAIRE

    Shibue, M.; Mant, C.T.; Hodges, R.S.

    2005-01-01

    The addition of salts, specifically sodium perchlorate (NaClO4), to mobile phases at acidic pH as ion-pairing reagents for reversed-phase high-performance liquid chromatography (RP-HPLC) has been generally overlooked. To demonstrate the potential of NaClO4 as an effective anionic ion-pairing reagent, we applied RP-HPLC in the presence of 0–100 mM sodium chloride (NaCl), sodium trifluoroacetate (NaTFA) or NaClO4 to two mixtures of synthetic 18-residue peptides: a mixture of peptides with the s...

  14. Peripartal calcium homoeostasis of multiparous dairy cows fed rumen-protected rice bran or a lowered dietary cation/anion balance diet before calving

    NARCIS (Netherlands)

    Martin-Tereso, J.; Wijlen, ter H.; Laar, van H.; Verstegen, M.W.A.

    2014-01-01

    Milk fever is one of the most important metabolic diseases in dairy cattle. Reducing the dietary cation/anion balance (DCAD) with anionic salts is a common prevention strategy. However, many small European farms cannot use total mixed rations (TMR) in the close-up period. Including anionic salts in

  15. Influence of Accompanying Anions on Potassium Retention and Leaching in Potato Growing Alluvial Soils

    Institute of Scientific and Technical Information of China (English)

    V.SHARMA; K.N.SHARMA

    2013-01-01

    A column study was carried out to assess the influence of accompanying anions on potassium (K) leaching at potato growing sites with different soil textures (sandy loam and clay loam) in northwestern India.Potassium was applied in the top 15 cm layer of soil column at 30 and 60 mg K kg-1 through different sources having different accompanying anions (Cl-,SO42-,NO3-and H2PO4-).Maximum K was retained in the top 0-15 cm layer with a sharp decrease in K content occurring in 15-30 cm layer of the soil column.The trend was similar for both levels of applied K as well as frequency of leaching and soil type.The decrease of K content in soil column after four leaching events was maximum in case of Khanaura sandy loam,while only minor decrease was observed in Hundowal clay loam when K was applied at 60 mg K kg-1,indicating higher potential of clay rich soil to adsorb K.In general,the K leaching in presence of the accompanying anions followed the order of SO42-≤ H2PO42-< NO3-=Cl-.Highest 1 mol L-1 CH3COONH4-extractable K was retained when K was applied along with SO42-and H2PO4-anions,and the least was retained when accompanying anion was Cl-.The influence of anions was more pronounced in the light textured soil and at high amounts of K application.Higher levels of K application resulted in higher losses of K,especially in sandy loam soil as observed from the leachate concentration.Among the different K sources,the maximum amount of K leaching was noticed in the soil column amended with KCl.After four leachings,the maximum amount of K leached out was 6.40 mg L-1 in Hundowal clay loam and 9.29 mg L-1 in Khanaura sandy loam at 60 mg K kg-1 of soil application through KCl.These concentrations were lower than the recommended guideline of the World Health Organisation (12.00 mg L-1).

  16. Potentiometric anion selectivity of polymer-membrane electrodes based on cobalt, chromium, and aluminum salens

    Energy Technology Data Exchange (ETDEWEB)

    Badr, Ibrahim H.A. [Department of Chemistry, Faculty of Science, Ain Shams University, P.O. Box 11566, Cairo (Egypt)]. E-mail: ibadr1@yahoo.com

    2006-06-16

    Metallo-salens of cobalt(II) (Co-Sal), chromium(III) (Cr-Sal), and aluminum(III) (Al-Sal) are used as the active ionophores within plasticized poly(vinyl chloride) membranes. It is shown that central metal-ion plays a critical role in directing the ionophore selectivity. Polymer-membrane electrodes based on Co-Sal, Cr-Sal, and Al-Sal are demonstrated to exhibit enhanced responses and selectivity toward nitrite/thiocyanate, thiocyanate, and fluoride anions, respectively. The improved anion selectivity of the three ionophore systems is shown to deviate significantly from the classical Hofmeister pattern that is based only on ion lipophilicity. For example, optimized membrane electrodes for nitrite ion based on Co-Sal exhibit logK{sub Nitrite,Anion}{sup pot} values of -5.22, -4.66, -4.48, -2.5 towards bromide, perchlorate, nitrate, and iodide anions, respectively. Optimized membrane electrodes based on Co-Sal and Cr-Sal show near-Nernstian responses towards nitrite (-57.9+/-0.9mV/decade) and thiocyanate (-56.9+/-0.8mV/decade), respectively, with fast response and recovery times. In contrast, Al-Sal based membrane electrodes respond to fluoride ion in a super-Nernstian (-70+/-3mV/decade) and nearly an irreversible mode. The operative response mechanism of Co-Sal, Cr-Sal, and Al-Sal membrane electrodes is examined using the effect of added ionic sites on the potentiometric response characteristics. It is demonstrated that addition of lipophilic anionic sites to membrane electrodes based on the utilized metallo-salens enhances the selectivity towards the primary ion, while addition of cationic sites resulted in Hofmeister selectivity patterns suggesting that the operative response mechanism is of the charged carrier type. Electron spin resonance (ESR) data indicates that Co(II) metal-ion center of Co-Sal ionophore undergoes oxidation to Co(III). This process leads to formation of a charged anion-carrier that is consistent with the response behavior obtained for Co

  17. Influence of specific anions on the orientational ordering of thermotropic liquid crystals at aqueous interfaces.

    Science.gov (United States)

    Carlton, Rebecca J; Ma, C Derek; Gupta, Jugal K; Abbott, Nicholas L

    2012-09-01

    We report that specific anions (of sodium salts) added to aqueous phases at molar concentrations can trigger rapid, orientational ordering transitions in water-immiscible, thermotropic liquid crystals (LCs; e.g., nematic phase of 4'-pentyl-4-cyanobiphenyl, 5CB) contacting the aqueous phases. Anions classified as chaotropic, specifically iodide, perchlorate, and thiocyanate, cause 5CB to undergo continuous, concentration-dependent transitions from planar to homeotropic (perpendicular) orientations at LC-aqueous interfaces within 20 s of addition of the anions. In contrast, anions classified as relatively more kosmotropic in nature (fluoride, sulfate, phosphate, acetate, chloride, nitrate, bromide, and chlorate) do not perturb the LC orientation from that observed without added salts (i.e., planar orientation). Surface pressure-area isotherms of Langmuir films of 5CB supported on aqueous salt solutions reveal ion-specific effects ranking in a manner similar to the LC ordering transitions. Specifically, chaotropic salts stabilized monolayers of 5CB to higher surface pressures and areal densities (12.6 mN/m at 27 Å(2)/molecule for NaClO(4)) and thus smaller molecular tilt angles (30° from the surface normal for NaClO(4)) than kosmotropic salts (5.0 mN/m at 38 Å(2)/molecule with a corresponding tilt angle of 53° for NaCl). These results and others reported herein suggest that anion-specific interactions with 5CB monolayers lead to bulk LC ordering transitions. Support for the proposition that these ion-specific interactions involve the nitrile group was obtained by using a second LC with nitrile groups (E7; ion-specific effects similar to 5CB were observed) and a third LC with fluorine-substituted aromatic groups (TL205; weak dipole and no ion-specific effects were measured). Finally, we also establish that anion-induced orientational transitions in micrometer-thick LC films involve a change in the easy axis of the LC. Overall, these results provide new insights

  18. Control of calcium carbonate crystallization by using anionic polymethylsiloxanes as templates

    Energy Technology Data Exchange (ETDEWEB)

    Neira-Carrillo, Andronico, E-mail: aneira@uchile.cl [Faculty of Veterinary and Animal Sciences, University of Chile, Santa Rosa 11735, PO Box 2-15, Santiago (Chile); Vasquez-Quitral, Patricio; Paz Diaz, Maria; Soledad Fernandez, Maria; Luis Arias, Jose [Faculty of Veterinary and Animal Sciences, University of Chile, Santa Rosa 11735, PO Box 2-15, Santiago (Chile); Yazdani-Pedram, Mehrdad [Faculty of Chemical and Pharmaceutical Science, University of Chile, S. Livingstone 1007, PO Box 233, Santiago (Chile)

    2012-10-15

    Sulfonated (SO{sub 3}H-PMS) and carboxylated (CO{sub 2}H-PMS) polymethylsiloxanes were synthesized and their effects as anionic template modifier on the CaCO{sub 3} crystal morphologies were evaluated. In vitro crystallization assays of CaCO{sub 3} were performed at room temperature by using gas diffusion method at different concentration, pH and time. SEM images of CaCO{sub 3} showed well-defined short calcite piles (ca. 5 {mu}m) and elongated calcite (ca. 20 {mu}m) when SO{sub 3}H-PMS was used. When CO{sub 2}H-PMS was used, the morphology of CaCO{sub 3} crystals was single-truncated at pH 7-9 and aggregated-modified calcite at pH 10-11. However, at pH 12 the least stable donut-shaped vaterite crystals were formed. EDS and XRD confirmed the presence of Si from anionic PMS templates on the CaCO{sub 3} surfaces and its polymorphism, respectively. Results showed that the selective morphologies of CaCO{sub 3} reflect the electrostatic interaction of anionic groups of functionalized PMS with Ca{sup 2+} adsorbed on CaCO{sub 3} crystals. Rounded and truncated-modified fluorescent CaCO{sub 3} was also produced by the inclusion of functionalized PMS into the lattice of CaCO{sub 3} matrix. We demonstrated that the anionic PMS offer a good modifier for polymer-controlled crystallization and a convenient approach for understanding the biomineralization field. - Graphical abstract: Optical photographs of rounded and truncated-modified fluorescent CaCO{sub 3} produced by the inclusion of sulfonated (SO{sub 3}H-PMS) polymethylsiloxanes into the lattice of CaCO{sub 3} matrix. Insert represents the simulation of modified and fluorescent CaCO{sub 3} crystals using Software JCrystal, (2008). Highlights: Black-Right-Pointing-Pointer We prepared two anionic polymethylsiloxanes (PMS) as templates. Black-Right-Pointing-Pointer Their modifier capacity on the CaCO{sub 3} crystal morphologies was demonstrated. Black-Right-Pointing-Pointer At pH 12, the least stable donut-shaped vaterite

  19. Determination of trace anions in liquefied petroleum gas using liquid absorption and electrokinetic migration for enrichment followed by ion chromatography.

    Science.gov (United States)

    Li, Meilan; Yang, Jianmin; Li, Hai-Fang; Lin, Jin-Ming

    2012-06-01

    A simple sample enrichment technique, electrokinetic migration enrichment in single phase using a designed device, coupled with ion chromatography is presented for the determination of four anions (H(2)PO(4)(-), Cl(-), NO(3)(-), and SO(4)(2-)) in liquefied petroleum gas by liquid adsorption. The electrokinetic migration enrichment is based on the phenomenon of ion electrokinetic migration to the opposite electrode. When the anions migrated to the anode in a smaller volume chamber under the electric field, the concentration was realized. The main parameters affecting enrichment efficiency of applied voltage and enrichment time were investigated. The ion chromatography condition for anions separation was also studied. Under the optimal electrokinetic migration enrichment and ion chromatography conditions, the four anions were detected simultaneously with good linear relationship (r(2) = 0.9908-0.9968) and high precisions (less than 5% of the relative standard deviations of peak areas). The limits of detection of anions (S/N of 3) were in the range of 8-600 μg L(-1). The enrichment factors of the four anions ranged from 3.1 to 5.8. The established method was successfully applied to the analysis of the trace anions in liquefied petroleum gas by liquid adsorption with satisfactory results. The advantages of this method are simple operation and low cost.

  20. Preparation1 and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to reduce the impact of eutrophication caused by agricultural residues (i.e. excess nitrate) in aqueous solution, economic and effective anionic sorbents are required. In this article, we prepared anionic sorbent using wheat straw. Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated. The results indicate that the yield of the prepared anionic sorbent, the total exchange capacity, and the maximum adsorption capacity were 350%, 2.57 mEq/g, and 2.08 mmol/g, respectively. The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation. When multiple anions (SO42-, H2PO4-, NO3-, and NO2-) were present, the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode; however, the capacity of nitrate adsorption was reduced by 50%. In alkaline solutions, about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent. The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.

  1. Anion Effects on the Ion Exchange Process and the Deformation Property of Ionic Polymer Metal Composite Actuators

    Directory of Open Access Journals (Sweden)

    Wataru Aoyagi

    2016-06-01

    Full Text Available An ionic polymer-metal composite (IPMC actuator composed of a thin perfluorinated ionomer membrane with electrodes plated on both surfaces undergoes a large bending motion when a low electric field is applied across its thickness. Such actuators are soft, lightweight, and able to operate in solutions and thus show promise with regard to a wide range of applications, including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. However, the variations induced by changing the type of anion on the device deformation properties are not well understood; therefore, the present study investigated the effects of different anions on the ion exchange process and the deformation behavior of IPMC actuators with palladium electrodes. Ion exchange was carried out in solutions incorporating various anions and the actuator tip displacement in deionized water was subsequently measured while applying a step voltage. In the step voltage response measurements, larger anions such as nitrate or sulfate led to a more pronounced tip displacement compared to that obtained with smaller anions such as hydroxide or chloride. In AC impedance measurements, larger anions generated greater ion conductivity and a larger double-layer capacitance at the cathode. Based on these mechanical and electrochemical measurements, it is concluded that the presence of larger anions in the ion exchange solution induces a greater degree of double-layer capacitance at the cathode and results in enhanced tip deformation of the IPMC actuators.

  2. Photocatalytic O{sub 2} evolution from water over Zn–Cr layered double hydroxides intercalated with inorganic anions

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Naoya [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Tadanaga, Kiyoharu, E-mail: tadanaga@eng.hokudai.ac.jp [Faculty of Engineering, Hokkaido University, Kita-Ku, Sapporo 060-8628 (Japan); Tatsumisago, Masahiro [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

    2015-02-15

    Graphical abstract: The photocatalytic activity of Zn–Cr LDHs intercalated with various inorganic anions was studied by O{sub 2} evolution from aqueous solution of AgNO{sub 3} as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. The interlayer anions affected the photocatalytic activity of the LDHs. - Highlights: • Zn–Cr layered double hydroxides intercalated with inorganic anions were synthesized. • Photocatalytic activity of the LDHs was studied by O{sub 2} evolution. • All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. • The interlayer anions affected the photocatalytic activity of the LDHs. - Abstract: Zn–Cr layered double hydroxides (LDHs) intercalated with inorganic anions (CO{sub 3}{sup 2−}, Cl{sup −}, SO{sub 4}{sup 2−} and NO{sub 3}{sup −}) were synthesized by the co-precipitation method and the anion exchange process. The photocatalytic activity of the LDHs was studied by O{sub 2} evolution from aqueous solution of AgNO{sub 3} as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. Besides, the interlayer anions affected the photocatalytic activity of the LDHs. After irradiation, Ag particles were formed on the LDHs by accepting the electrons generated during the photocatalytic reaction.

  3. First observation of alkyne radical anions by electron spin resonance spectroscopy: Hexyne/n-hexane mixed crystals

    International Nuclear Information System (INIS)

    The radical anions of alkynes have been first observed by electron spin resonance spectroscopy following alkene anions previously studied. Hexyne radical anions were formed in 1-, 2-, or 3-hexyne/n--hexane mixed crystals irradiated at 4.2 or 77 K. The characters of the anions were as follows; (a) the α-proton hyperfine coupling is very large (∼4.5 mT for the 1-hexyne anion), (b) the β-proton couplings are very small (∼1.0 mT for C--Hβ proton with the conformational angle of 0 degree), and (c) the radicals show a negative g shift (2.0014). From these observations, it was found that the anions have a nonlinear(bent) molecule structure in the anticonfiguration (trans C--C≡C--C) with the bend angle ∼60 degree, and that the unpaired electron orbital is approximately composed of the anticombination of the sp2 hybrid orbitals of the C≡C carbon atoms. A discussion based on complete neglect of differential overlap (CNDO) molecular orbital (MO) calculations was given for the observed negative g shift, which was shown to be characteristic of the alkyne anions which have a high-lying unpaired electron orbital and an antibonding 2p--2p π carbon orbital just above it on the upper energy side

  4. Self-assembled arene-ruthenium-based rectangles for the selective sensing of multi-carboxylate anions.

    Science.gov (United States)

    Vajpayee, Vaishali; Song, Young Ho; Lee, Min Hyung; Kim, Hyunuk; Wang, Ming; Stang, Peter J; Chi, Ki-Whan

    2011-07-01

    Novel arene-ruthenium [2+2] metalla-rectangles 4 and 5 have been synthesized by self-assembly using dipyridyl amide ligand 3 and arene-ruthenium acceptors (arene: benzoquinone (1), naphthacenedione (2)) and characterized by NMR spectroscopy and ESI-MS. The solid-state structure of 5 was determined by X-ray diffraction and shows encapsulated diethyl ether molecule in the rectangular cavity of 5. The luminescent 5 was further used for anion sensing with the amidic linkage serving as a hydrogen-bond donor site for anions and the ruthenium moiety serving as a signaling unit. A UV/Vis titration study demonstrated that although 5 interacts very weakly with common monoanions as well as with flexible dicarboxylate anions such as malonate and succinate, it displays significant binding affinity (K>10(3) in MeOH) for rigid multi-carboxylate anions such as oxalate, citrate, and tartrate, exhibiting a 1:1 stoichiometry. It has been suggested that 1:1 bidentate hydrogen bonding assisted by appropriate geometrical complementarity is mainly responsible for the increased affinity of 5 towards such anions. A fluorescence titration study revealed a large fluorescence enhancement of 5 upon binding to multi-carboxylate anions, which can be attributed to the blocking of the photoinduced electron-transfer process from the arene-Ru moiety to the amidic donor in 5 as a result of hydrogen bonding between the donor and the anion.

  5. Evidence for functional interaction of plasma membrane electron transport, voltage-dependent anion channel and volume-regulated anion channel in frog aorta

    Indian Academy of Sciences (India)

    Rashmi P Rao; J Prakasa Rao

    2010-12-01

    Frog aortic tissue exhibits plasma membrane electron transport (PMET) owing to its ability to reduce ferricyanide even in the presence of mitochondrial poisons, such as cyanide and azide. Exposure to hypotonic solution (108 mOsmol/kg H2O) enhanced the reduction of ferricyanide in excised aortic tissue of frog. Increment in ferricyanide reductase activity was also brought about by the presence of homocysteine (100 M dissolved in isotonic frog Ringer solution), a redox active compound and a potent modulator of PMET. Two plasma-membrane-bound channels, the volume regulated anion channel (VRAC) and the voltage-dependent anion channel (VDAC), are involved in the response to hypotonic stress. The presence of VRAC and VDAC antagonists–tamoxifen, glibenclamide, fluoxetine and verapamil, and 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid (DIDS), respectively–inhibited this enhanced activity brought about by either hypotonic stress or homocysteine. The blockers do not affect the ferricyanide reductase activity under isotonic conditions. Taken together, these findings indicate a functional interaction of the three plasma membrane proteins, namely, ferricyanide reductase (PMET), VDAC and VRAC.

  6. Effects of Polar Organic Solvent on Separation of Y(edta)-/Nd(edta)- Complexes on Polyacrylic Anion Exchangers

    Institute of Scientific and Technical Information of China (English)

    Halina Hubicka; Dorota Kolodynska

    2005-01-01

    The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exchangers, particularly the weakly basic, gel anion exchanger Amberlite IRA 68, can be applied to the separation of rare earth complexes with EDTA in H2O-methanol and H2O-ethanol systems. In most cases the determined distribution coefficients of Ln3+ complexes with EDTA in mixed media like water-methanol on polyacrylate anion exchangers are larger than those in pure water media.

  7. Application of monohydric phenols as mobile-phase modifiers in the determination of anions by two-column ion chromatography

    International Nuclear Information System (INIS)

    The effect of monohydric phenols as eluant-modifying additives on the determination of I- and MoO42- anions by ion chromatography was studied. The following phenols were examined: pentafluorophenol, 4-nitrophenol, 2-nitrophenol, 2,4-dinitrophenol, and 4-chlorphenol. It was found that these phenols selectively affect the retention times of weakly and strongly retained anions. A correlation between pKa and the concentration of additive, and the retention times of anions was found. 12 refs., 3 figs., 3 tabs

  8. Anion-induced exchange interactions in binuclear complexes of Cu(II) with flexible hexadentate bispicolylamidrazone ligands

    Science.gov (United States)

    Baryshnikov, Gleb V.; Minaev, Boris F.; Baryshnikova, Alina A.; Ågren, Hans

    2016-09-01

    Two recently synthesized copper(II) complexes with spacer-armed bispicolylamidrazone ligands have been theoretically studied at the density functional theory (DFT) level accounting for empirical dispersion correction and intrinsic anionic environment by perchlorate ions. The exchange parameter between the open-shell singlet and triplet states of the studied complexes has been estimated by broken symmetry DFT calculations. The mechanism of spin-spin exchange interaction between the unpaired electrons via the σ-bond aliphatic chain (Gusev et al., 2015) is confirmed. Instead, a anion-induced mechanism is proposed which means that the anionic grid participates in the exchange interaction between the unpaired electrons.

  9. Inductive effects of 10 and 12-vertex closo-carborane anions: cluster size and charge make a difference.

    Science.gov (United States)

    Estrada, Jess; Lugo, Christopher A; McArthur, Scott G; Lavallo, Vincent

    2016-01-31

    A phosphine containing a 10-vertex carborane anion substituent and its subsequent ligation to a Rh(I) carbonyl complex is reported. The complex is characterized by NMR spectroscopy and a single crystal X-ray diffraction study. In addition, the inductive effects of both 10 and 12 vertex C-functionalized closo-carborane anions are elucidated via I.R. analysis of the CO stretching frequencies of two Rh carbonyl complexes. Unlike C-functionalized neutral o-carborane the 10 and 12-vertex carborane anions are both strong electron donor substituents. PMID:26671630

  10. Photocatalytic O-2 evolution from water over Zn-Cr layered double hydroxides intercalated with inorganic anions

    OpenAIRE

    Hirata, Naoya; TADANAGA, Kiyoharu; Tatsumisago, Masahiro

    2015-01-01

    Zn-Cr layered double hydroxides (LDHs) intercalated with inorganic anions (CO32-, Cl-, SO42- and NO3-) were synthesized by the co-precipitation method and the anion exchange process. The photocatalytic activity of the LDHs was studied by O-2 evolution from aqueous solution of AgNO3 as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. Besides, the interlayer anions affected the photocatalytic activity of the LDHs. After ...

  11. Electron capture by fluorinated fullerene anions in collisions with Xe atoms

    DEFF Research Database (Denmark)

    Boltalina, OV; Hvelplund, P; Jørgensen, Thomas J. D.;

    2000-01-01

    Electron capture by 50-keV fluorinated fullerene anions (C60Fn- 18anions (C60Fn- 18

  12. Atomic force microscopy study of anion intercalation into highly oriented pyrolytic graphite

    Energy Technology Data Exchange (ETDEWEB)

    Alliata, D.; Haering, P.; Haas, O.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegenthaler, H. [University of Berne (Switzerland)

    1999-08-01

    In the context of ion transfer batteries, we studied highly oriented pyrolytic graphite (HOPG) in perchloric acid, as a model to elucidate the mechanism of electrochemical intercalation in graphite. Aim of the work is the local and time dependent investigation of dimensional changes of the host material during electrochemical intercalation processes on the nanometer scale. We used atomic force microscopy (AFM), combined with cyclic voltammetry, as in-situ tool of analysis during intercalation and expulsion of perchloric anions into the HOPG electrodes. According to the AFM measurements, the HOPG interlayer spacing increases by 32% when perchloric anions intercalate, in agreement with the formation of stage IV of graphite intercalation compounds. (author) 3 figs., 3 refs.

  13. Non-adiabatic dynamics of isolated green fluorescent protein chromophore anion

    International Nuclear Information System (INIS)

    On-the-fly ab initio molecular dynamics calculations have been performed to investigate the relaxation mechanism of green fluorescent protein chromophore anion under vacuum. The CASSCF surface hopping simulation method based on Zhu-Nakamura theory is applied to present the real-time conformational changes of the target molecule. The static calculations and dynamics simulation results suggest that not only the twisting motion around bridging bonds between imidazolinone and phenoxy groups but the strength mode of C=O and pyramidalization character of bridging atom are major factors on the ultrafast fluorescence quenching process of the isolated chromophore anion. The abovementioned factors bring the molecule to the vicinity of conical intersections on its potential energy surface and to finish the internal conversion process. A Hula-like twisting pattern is displayed during the relaxation process and the entire decay process disfavors a photoswitching pattern which corresponds to cis-trans photoisomerization

  14. A novel naphthalene-based receptor: Colorimetric and fluorescent PET chemoreceptor for anions

    Energy Technology Data Exchange (ETDEWEB)

    Huang Weiwei; Su Hongyan; Yao Sikai; Yang Zhongyue [Department of Chemistry, Nankai University, Tianjin 300071 (China); Lin Hai [Key Laboratory of Functional Polymer Materials of Ministry of Education, Nankai University, Tianjin 300071 (China); Lin Huakuan, E-mail: hklin@nankai.edu.cn [Department of Chemistry, Nankai University, Tianjin 300071 (China)

    2011-09-15

    A novel artificial anion receptor based on phenylhydrazone structure was designed, synthesized and characterized. The binding behavior of the receptor to various anions was investigated by UV-vis fluorescence analyses. In addition, {sup 1}H NMR experiments were carried out to explore the nature of interaction between receptor 1 and acetate. The processes of sensing can literally be seen through the 'naked-eye' for the sharp color changes from yellow to purple. - Highlights: > The synthesis process of receptor 1 (1-hydroxynaphthalene-2-carbaldehyde-4'-nitrophenylhydrazone) is simple and easy. Thus, it made practical use of receptor 1 possible. > Receptor 1 displays distinct color changes from yellow to purple, which could be observed by the naked eye. In addition, the sensing process is fast and efficient. > Receptor 1 can recognize acetates which is of great importance since acetates are important biological molecules.

  15. Aliphatic C-H---Anion Hydrogen Bonds: Weak Contacts or Strong Interactions?

    Energy Technology Data Exchange (ETDEWEB)

    Hay, Benjamin [ORNL; Pedzisa, Lee [ORNL

    2009-01-01

    Electronic structure calculations, MP2/aug-cc-pVDZ, are used to determine C H---Cl hydrogen bond energies for a series of XCH3 donor groups in which the electron-withdrawing ability of X is varied over a wide range of values. When attached to polarizing substituents, aliphatic CH groups are moderate to strong hydrogen bond donors, exhibiting interaction energies comparable to those obtained with O H and N H groups. The results explain why aliphatic C H donors are observed to function as competitive binding sites in solution and suggest that such C H---anion contacts should be considered as possible contributors when evaluating the denticity of an anion receptor.

  16. Ionic strength dependent vesicle adsorption and phase behavior of anionic phospholipids on a gold substrate.

    Science.gov (United States)

    Pramanik, Sumit Kumar; Seneca, Senne; Ethirajan, Anitha; Neupane, Shova; Renner, Frank Uwe; Losada-Pérez, Patricia

    2016-03-08

    The authors report on the effect of ionic strength on the formation of supported vesicle layers of anionic phospholipids 1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol (DMPG) and dimyristoylphosphatidylserine (DMPS) onto gold. Using quartz crystal microbalance with dissipation monitoring the authors show that vesicle adsorption is mainly governed by NaCl concentration, reflecting the importance of electrostatic interactions in anionic lipids, as compared to zwitterionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine. At low ionic strength, low or no adsorption is observed as a result of vesicle-vesicle electrostatic repulsion. At medium ionic strength, the negative charges of DMPG and DMPS are screened resulting in larger adsorption and a highly dissipative intact vesicle layer. In addition, DMPS exhibits a peculiar behavior at high ionic strength that depends on the temperature of the process.

  17. Proton transfer from 1,4-pentadiene to superoxide radical anion: a QTAIM analysis

    Directory of Open Access Journals (Sweden)

    Angela Rodríguez-Serrano

    2014-04-01

    Full Text Available We studied the bis-allylic proton transferreaction from 1,4-pentadiene to superoxideradical anion (O2·־. Minima andtransition state geometries, as well asthermochemical parameters were computedat the B3LYP/6-311+G(3df,2plevel of theory. The electronic wavefunctions of reactants, intermediates,and products were analyzed within theframework of the Quantum Theory ofAtoms in Molecules. The results showthe formation of strongly hydrogen bondedcomplexes between the 1,4-pentadien-3-yl anion and the hydroperoxylradical as the reaction products. Theseproduct complexes (PCs are more stablethan the isolated reactants and muchmore stable than the isolated products.This reaction occurs via pre-reactivecomplexes which are more stable thanthe PCs and the transition states. This isin agreement with the fact that the netproton transfer reaction that leads to freeproducts is an endothermic and nonspontaneousprocess.

  18. Neccessite d'un anion exogene mobile en cas de nutrition ammoniacale

    OpenAIRE

    Soltani, A.; Hajji, M; Grignon, C

    1989-01-01

    Des plantules d’orge âgées de 6 j sont cultivées pendant 1 mois sur des milieux contenant NO-3 ou NH+4 comme source de N. Des variantes de ces milieux permettent de comparer les effets de la mobilité de l’anion qui accompagne NH+4 (Cl-, facilement absorbé, ou SO2-4, peu mobile). La réduction de croissance, classiquement décrite lorsque NH+4 est substitué à NO-3, apparaît seulement quand l’anion majeur est SO2-4. Avec Cl-, les 2 sources d’azote permettent des croissances semblables. Dans le ca...

  19. Mutual neutralization of He+ with the anions Cl-, Br-, I-, and SF6-

    Science.gov (United States)

    Wiens, Justin P.; Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.

    2016-05-01

    Mutual neutralization (MN) rate coefficients kMN for He+ with the anions Cl-, Br-, I-, and SF6- are reported from 300 to 500 K. The measured rate coefficients may contain a contribution from transfer ionization, i.e., double ionization of the anion. The large rate coefficient for He+ + SF6- (2.4 × 10-7 cm3 s-1 at 300 K) is consistent with earlier polyatomic MN results found to have a reduced mass dependence of μ-1/2. Neutralization of He+ by the atomic halides follows the trend observed earlier for Ne+, Ar+, Kr+, and Xe+ neutralized by atomic halides, kMN (Cl-) SF6- is small or negligible.

  20. Mutual neutralization of He(+) with the anions Cl(-), Br(-), I(-), and SF6 (.).

    Science.gov (United States)

    Wiens, Justin P; Shuman, Nicholas S; Miller, Thomas M; Viggiano, Albert A

    2016-05-28

    Mutual neutralization (MN) rate coefficients kMN for He(+) with the anions Cl(-), Br(-), I(-), and SF6 (-) are reported from 300 to 500 K. The measured rate coefficients may contain a contribution from transfer ionization, i.e., double ionization of the anion. The large rate coefficient for He(+) + SF6 (-) (2.4 × 10(-7) cm(3) s(-1) at 300 K) is consistent with earlier polyatomic MN results found to have a reduced mass dependence of μ(-1/2). Neutralization of He(+) by the atomic halides follows the trend observed earlier for Ne(+), Ar(+), Kr(+), and Xe(+) neutralized by atomic halides, kMN (Cl(-)) SF6 (-) is small or negligible. PMID:27250308