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Sample records for investigated anions including

  1. Metal-Anion Pairing at Oxide/Water Interfaces: Theoretical and Experimental Investigations from the Nanoscale to the Macroscale

    SciTech Connect

    Allen, Heather

    2016-11-14

    We combine the use of several techniques including bulk adsorption experiments, X-ray absorption, infrared, total internal reflection Raman, and vibrational sum frequencygeneration (XAS, IR, TIR-Raman, VSFG) spectroscopies, and molecular modeling to investigate ion adsorption at mineral surfaces. XAS and TIR-Raman provides data on how the metal binds to the surface (e.g., monodentate, bidentate), IR provides data on bulk anion adsorption at mineral surfaces from aqueous solutions, and VSFG provides surface specific data on anion adsorption at the mineral surface as well as impact of adsorbed metal-anion pairs on water structure at the mineral surface. Molecular modeling is used to guide spectroscopic data interpretation by providing information on water structure around ions in solution and the structure of metal-anion complexes in aqueous solutions. In addition, molecular modeling is used to provide insight into water structure at mineral surfaces, the surface sites involved in ion adsorption, and the distribution of ion pairs between aqueous solution and the mineral surface. Our studies have focused on systems involving alkaline earth metal (Mg2+, Ca2+, Sr2+, Ba2+) and heavy metal (Co2+, Cd2+) cations. The anions we have selected for studyinclude Cl-, NO3-, ClO4-, SO42-, SeO32-, and SeO42-. Ion adsorption and the potential formation ofternary complexes on silica (quartz, amorphous silica), alumina (corundum and gibbsite), and ferric iron oxides (goethite and hematite) are under investigation.

  2. N-acetylglyoxylic amide bearing a nitrophenyl group as anion receptors: NMR and X-ray investigations on anion binding and selectivity

    NASA Astrophysics Data System (ADS)

    Suryanti, Venty; Bhadbhade, Mohan; Black, David StC; Kumar, Naresh

    2017-10-01

    N-Nitrophenylglyoxylic amides 1 and 2 in presence of tetrabutylammonium cation (TBA) act as receptors for anions HSO4-, Cl-, Br- and NO3- as investigated by NMR studies. The receptors formed 1:1 host-guest complexes in solution. X-ray structure of 1 along with TBA that bind a chloride anion is reported. Molecule 1 showed the highest selectivity for HSO4- anion over others measured. X-ray structure of the bound Cl- revealed a pocket containing the anion making strong (Nsbnd H⋯Cl) and weak hydrogen bonds (Csbnd H⋯Cl) that contribute to the recognition of the chloride anion. Nsbnd H and Csbnd H hydrogen bonds resulted in a relatively strong binding for chloride ions.

  3. Quantum-chemical investigations of small molecular anions

    NASA Astrophysics Data System (ADS)

    Botschwina, P.; Seeger, S.; Mladenović, M.; Schulz, B.; Horn, M.; Schmatz, S.; Flügge, J.; Oswald, R.

    Dedicated to Dr Gerhard Herzberg on the occasion of his 90th birthday Recent large-scale ab initio calculations for small negative molecular ions are reviewed. Accurate equilibrium geometries are established for several species like NH2-, HCC-, NO2-, CH2N- C5- and C6-. Predictions are made for various spectroscopic properties like vibrational frequencies, rotational constants and infrared intensities. The effects of a shallow energy minimum in the T-shaped configuration on the rovibrational term energies of HCC - are investigated. The calculated vibrational structures of the photoelectron spectra of SiH3- and CH2N - are in very good agreement with the experiment. The present calculations support the assignment of an absorption observed at 608 nm in a neon matrix to the

  4. Quantum-Chemical Investigations on the Structural Variability of Anion-π Interactions

    NASA Astrophysics Data System (ADS)

    Moha, Verena; Giese, Michael; Moha, Richard; Albrecht, Markus; Raabe, Gerhard

    2014-07-01

    The structural versatility of anion-p interactions was investigated computationally. Employing quantum-chemically optimized structures of a series of C6H6-nFn/Br- complexes and the Coulomb law together with the London formula to calculate the electrostatic and the dispersion energy of the interaction between the anion and the π-system led to the result that up to the number of n = 2 due to a significantly repulsive electrostatic energy of interaction the dispersion energy is not sufficient to stabilize such structures in the gas phase where the anion is located above the plane defined by the aromatic ring. The energy surfaces resulting from the interaction of bromide anions with isolated arenes bearing varying numbers of fluorine atoms in different positions of the aromatic ring also show a pronounced dependency on the subsitution pattern of the aromatic system. Depending on the nature of the electron withdrawing group and its position, the energy surface can have a sharply defined energetically low minimum, in which the anion is `fixed'. Other substitution patterns result in very flat energy surfaces, and even a surface with more than two local minima within the scanned area was found. Thus, our study reveals the reason for the experimentally observed structural versatility depending on the substitution pattern in the solid state.

  5. Stable and highly persistent quinoxaline-centered metalloorganic radical anions: preparation, structural, spectroscopic, and computational investigations.

    PubMed

    Choua, Sylvie; Djukic, Jean-Pierre; Dalléry, Jérôme; Bieber, André; Welter, Richard; Gisselbrecht, Jean-Paul; Turek, Philippe; Ricard, Louis

    2009-01-05

    Coordination of diazines such as quinoxaline to transition metals stabilizes radical anions generated by chemical or electrochemical cathodic reduction. However, even though various sorts of radical anionic diazines have been subjected to spectroscopic investigations in the recent past, reports combining structural, solid-state electron paramagnetic resonance (EPR) and computational investigations of kinetically stable species are still missing. In this study, four radical anions derived from tricarbonylmanganese- and tricarbonylrhenium-bound quinoxaline chelates, embedded within a triple-decker architecture, have been prepared from neutral substrates by chemical reduction over alkaline metals (K, Rb); the electronic structure of the latter metalloorganic paramagnetic salts was investigated by the means of structural X-ray diffraction analysis, electrochemistry, solution and crystal EPR spectroscopy, and density functional theory (DFT). Unprecedented structures of three manganese-bound and one rhenium-bound quinoxaline-derived paramagnetic salts were obtained from solutions of the corresponding radical anions crystallized in the presence of cryptand 222. It is inferred from a comparative study of the structures of anionic and neutral quinoxaline complexes that reduction does not have any significant impact over the coordination mode of the metal centers and over the overall geometry of the triple-decker architecture. The most notable changes in the radical-anionic metalloorganic species, as compared to the neutral parent molecules, comprise a slight hapticity shift of the metal-bound benzyl moiety and a weak intraannular distortion of the quinoxalyl core. Single-crystal EPR experiments carried out with the rhenium and manganese compounds produced the respective anisotropic g tensor, which was found in each case to be essentially located at the quinoxalyl fragment. Computations, carried out using DFT methods (B3LYP-LANL2DZ and Becke-Perdew-TZP), corroborated the

  6. First evidence of epithelial transport in tardigrades: a comparative investigation of organic anion transport.

    PubMed

    Halberg, Kenneth Agerlin; Møbjerg, Nadja

    2012-02-01

    We investigated transport of the organic anion Chlorophenol Red (CPR) in the tardigrade Halobiotus crispae using a new method for quantifying non-fluorescent dyes. We compared the results acquired from the tardigrade with CPR transport data obtained from Malpighian tubules of the desert locust Schistocerca gregaria. CPR accumulated in the midgut lumen of H. crispae, indicating that organic anion transport takes place here. Our results show that CPR transport is inhibited by the mitochondrial un-coupler DNP (1 mmol l(-1); 81% reduction), the Na(+)/K(+)-ATPase inhibitor ouabain (10 mmol l(-1); 21% reduction) and the vacuolar H(+)-ATPase inhibitor bafilomycin (5 μmol l(-1); 21% reduction), and by the organic anions PAH (10 mmol l(-1); 44% reduction) and probenecid (10 mmol l(-1); 61% reduction, concentration-dependent inhibition). Transport by locust Malpighian tubules exhibits a similar pharmacological profile, albeit with markedly higher concentrations of CPR being reached in S. gregaria. Immunolocalization of the Na(+)/K(+)-ATPase α-subunit in S. gregaria revealed that this transporter is abundantly expressed and localized to the basal cell membranes. Immunolocalization data could not be obtained from H. crispae. Our results indicate that organic anion secretion by the tardigrade midgut is transporter mediated with likely candidates for the basolateral entry step being members of the Oat and/or Oatp transporter families. From our results, we cautiously suggest that apical H(+) and possibly basal Na(+)/K(+) pumps provide the driving force for the transport; the exact coupling between electrochemical gradients generated by the pumps and transport of ions, as well as the nature of the apical exit step, are unknown. This study is, to our knowledge, the first to show active epithelial transport in tardigrades.

  7. Quantum mechanical investigation of the inner-sphere reorganization energy of cyclooctatetraene/cyclooctatetraene radical anion. Part I.

    PubMed

    Kelterer, A M; Landgraf, S; Grampp, G

    2001-09-01

    The inner-sphere reorganization energy of the electron self-exchange of the couple cyclooctatetraene/cyclooctatetraene radical anion has been investigated by quantum mechanical calculations. The more stable Jahn Teller distorted B2g conformation of the radical anion has been used in this study. Two different theories have been applied in this first part. The harmonic approximation in the classical Marcus scheme has been modified by using projected force constants, which are obtained from the complete force constant matrix and the geometry changes of the molecule during the ET (introduced by Mikkelsen). A different approach (introduced by Nelsen) combines the different energies of the neutral and radical anion with and without relaxation corresponding to the vertical ionization potential and the vertical electron affinity. The electronic energies of the neutral molecule and the radical anion differ dramatically applying three different levels of quantum mechanical calculations (UAM1, UB3LYP, PMP2 with three different basis sets with and without diffuse functions). Nevertheless the Nelsen method gives almost consistent results for the inner-sphere reorganization energies: 120.1 kJ/mol for semiempirical UAM1 method, 159.3 kJ/mol, 156.4 kJ/mol and 158.3 kJ/mol for density functional UB3LYP/6-31G*, UB3LYP/6-31++G* and UB3LYP/AUG-cc-pVDZ calculations and 192.5 kJ/mol for ab-initio PMP2/6-31G* investigations, respectively. These values are in agreement with earlier experimental work supposing the total reorganization energy to be larger than 38 kcal/mol assuming an electron self-exchange rate of 10(4) M(-1) s(-1). The simple harmonic approximation of Marcus relation has not yet been applied for a molecule like cyclooctatetraene with large torsional geometry changes. Using the projected force constants after scaling, considerably different results for the inner-sphere reorganization energy have been calculated: 738.1 kJ/mol for the UB3LYP/6-31G*, 743.3 kJ/mol for UB3LYP/6

  8. Halotriazolium axle functionalised [2]rotaxanes for anion recognition: investigating the effects of halogen-bond donor and preorganisation.

    PubMed

    Mercurio, James M; Knighton, Richard C; Cookson, James; Beer, Paul D

    2014-09-08

    The anion-templated synthesis of three novel halogen-bonding 5-halo-1,2,3-triazolium axle containing [2]rotaxanes is described, and the effects of altering the nature of the halogen-bond donor atom together with the degree of inter-component preorganisation on the anion-recognition properties of the interlocked host investigated. The ability of the bromotriazolium motif to direct the halide-anion-templated assembly of interpenetrated [2]pseudorotaxanes was studied initially; bromide was found to be the most effective template. As a consequence, bromide anion templation was used to synthesise the first bromotriazolium axle containing [2]rotaxane, the anion-binding properties of which, determined by (1) H NMR spectroscopic titration experiments, revealed enhanced bromide and iodide recognition relative to a hydrogen-bonding protic triazolium rotaxane analogue. Two halogen-bonding [2]rotaxanes with bromo- and iodotriazolium motifs integrated into shortened axles designed to increase inter-component preorganisation were also synthesised. Anion (1) H NMR spectroscopic titration experiments demonstrated that these rotaxanes were able to bind halide anions even more strongly, with the iodotriazolium axle integrated rotaxane capable of recognising halides in aqueous solvent media. Importantly, these observations suggest that a halogen-bonding interlocked host binding domain, in combination with increased inter-component preorganisation, are requisite design features for a potent anion receptor.

  9. Anion channels, including ClC-3, are required for normal neutrophil oxidative function, phagocytosis, and transendothelial migration.

    PubMed

    Moreland, Jessica G; Davis, A Paige; Bailey, Gail; Nauseef, William M; Lamb, Fred S

    2006-05-05

    NADPH oxidase activity, phagocytosis, and cell migration are essential functions of polymorphonuclear leukocytes (PMNs) in host defense. The cytoskeletal reorganization necessary to perform these functions has been extensively studied, but the role of cell volume regulation, which is likely dependent upon anion channels, has not been defined. Mice lacking the anion channel ClC-3 (Clcn3(-/-)) died from presumed sepsis following intravascular catheter placement, whereas Clcn3(+/+) littermates survived. We hypothesized that ClC-3 has a critical role in host defense and reasoned that PMN function would be compromised in these mice. Clcn3(-/-) PMNs displayed markedly reduced NADPH oxidase activity in response to opsonized zymosan and modestly reduced activity after phorbol 12-myristate 13-acetate. Human PMNs treated with the anion channel inhibitors niflumic acid or 5-nitro-2-(3-phenylpropylamino)benzoic acid had a very similar defect. ClC-3 protein was detected in the secretory vesicles and secondary granules of resting PMNs and was up-regulated to the phagosomal membrane. Clcn3(-/-) PMNs and human PMNs lacking normal anion channel function both exhibited reduced uptake of opsonized zymosan at 1, 5, and 10 min in a synchronized phagocytosis assay. Niflumic acid-treated PMNs also had impaired transendothelial migration in vitro, whereas migration in vivo was not altered in Clcn3(-/-) PMNs. Selective inhibition of the swelling-activated chloride channel with tamoxifen profoundly reduced PMN migration but had no effect on NADPH oxidase activity. In summary, PMNs lacking normal anion channel function exhibited reduced NADPH oxidase activity, diminished phagocytosis, and impaired migration. ClC-3 was specifically involved in the respiratory burst and phagocytosis.

  10. Investigation of Anion-Exchange and Immunoaffinity Particle-Loaded Membranes for the Isolation of Charged Organic Analytes from Water

    USGS Publications Warehouse

    Dombrowski, T.R.; Wilson, G.S.; Thurman, E.M.

    1998-01-01

    Anion-exchange and immunoaffinity particle loaded membranes (PLMs) were investigated as a mechanism for the isolation of charged organic analytes from water. Kinetic properties determined theoretically included dynamic capacity, pressure drop (??P), residence and diffusion times (Tr, Td), and total membrane porosity (???T). These properties were confirmed through experimental evaluation, and the PLM method showed significant improvement over conventional solid-phase extraction (SPE) and ion-exchange formats. Recoveries of more than 90% were observed for a variety of test compounds at flow rates up to 70 mL/min (equipment-limited maximum flow rate). A fast-flow immunoaffinity column was developed using antibodies (Abs) attached to the PLMs. Reproducible recoveries (88% ?? 4%) were observed at flow rates up to 70 mL/min for the antibody (Ab)-loaded PLMs. Findings indicate increased selectivity over anion-exchange PLMs and conventional SPE or ion-exchange methods and rapid Ab-antigen binding rates given the excellent mass-transfer characteristics of the PLMs.

  11. Exploring rearrangements along the fragmentation pathways of diuron anion: A combined experimental and computational investigation

    NASA Astrophysics Data System (ADS)

    Kanawati, Basem; Harir, Mourad; Schmitt-Kopplin, Philippe

    2009-12-01

    Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), a common herbicide from phenyl urea class, was investigated by studying the formation of several negative ions [M-H]- in the gas phase and the fragmentation behaviour of the thermodynamically most probably formed isomeric anions upon linear ion acceleration/collision experiments. The collision induced dissociation experiments (CID) were carried out in a hexapole-quadrupole-hexapole hybrid system coupled to 12 T magnet with infinity ICR cell for high resolution measurements. Two distinctive main pathways were observed in the MS/MS spectrum. Sustained off-resonance irradiation (SORI) experiments inside the ICR cell reinforce the fragmentation channels obtained from linear ion acceleration experiments. The fragmentation pathways were also completely investigated by the use of B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d) level of theory. Elimination of dimethylamine takes place in a two-step process, by which two successive 1,3 proton shifts occur. The second 1,3 proton shift is concerted with the departure of dimethylamine. The driving force for the (CH3)2NH elimination is the formation of isocyanate group. The formed primary product ion can further decompose to release HCl through a new transition state. A stable new aromatic product ion is formed with 10[pi] electrons. Loss of C3H5NO neutral from another anionic isomer of the precursor ion was also observed and is characteristic for the amide terminal of the diamide functional group. A concerted mechanism is proposed, by which N-C bond breakage and cyclization of the eliminated neutral fragment C3H5NO takes place simultaneously to form 1-methyl-aziridin-2-one.

  12. Probing the early stages of salt nucleation—experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    SciTech Connect

    Deng, Shihu; Kong, Xiangyu; Wang, Xue B.

    2015-01-14

    are suppressed. The series of anion clusters investigated here range from molecular-like M₁(SCN)⁻2 to nano-sized K₂₂(SCN)³⁻25, providing a vivid molecular-level growth pattern reflecting the initial salt nucleation process.

  13. Probing the early stages of salt nucleation--experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions.

    PubMed

    Deng, S H M; Kong, Xiang-Yu; Wang, Xue-Bin

    2015-01-14

    . The series of anion clusters investigated here range from molecular-like M1(SCN)2(-) to nano-sized K22(SCN)25(3-), providing a vivid molecular-level growth pattern reflecting the initial salt nucleation process.

  14. Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    SciTech Connect

    Deng, S. H. M.; Kong, Xiang-Yu; Wang, Xue-Bin

    2015-01-14

    charged clusters were found to become preferred, but at higher temperatures, those multiply charged clusters were suppressed. The series of anion clusters investigated here range from molecular-like M{sub 1}(SCN){sub 2}{sup −} to nano-sized K{sub 22}(SCN){sub 25}{sup 3−}, providing a vivid molecular-level growth pattern reflecting the initial salt nucleation process.

  15. Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    NASA Astrophysics Data System (ADS)

    Deng, S. H. M.; Kong, Xiang-Yu; Wang, Xue-Bin

    2015-01-01

    clusters were suppressed. The series of anion clusters investigated here range from molecular-like M 1 (SCN)2 - to nano-sized K 22 (SCN)25 3 - , providing a vivid molecular-level growth pattern reflecting the initial salt nucleation process.

  16. Combined DFT and XPS investigation of iodine anions adsorption on the sulfur terminated (001) chalcopyrite surface

    NASA Astrophysics Data System (ADS)

    Li, Kui; Zhao, Yaolin; Zhang, Peng; He, Chaohui; Deng, Jia; Ding, Shujiang; Shi, Weiqun

    2016-12-01

    The adsorption of iodine anions (iodide and iodate) on the sulfur terminated (001) chalcopyrite surface has been systematically investigated combining first-principles calculations based on density functional theory (DFT) with X-ray photoelectron spectroscopy (XPS) measurements. Based on the total energy calculations and geometric optimization, the thermodynamically preferred site was copper atom for iodide adsorption and iron atom for iodate adsorption, respectively. In the case of Cu site mode, the iodate underwent a dissociative adsorption, where one Isbnd O bond of iodate ion was broken and the dissociative oxygen atom adsorbed on the adjacent sulphur site. Projected density of states (PDOS) analysis further clarified the interaction mechanism between active sites of chalcopyrite surface and adsorbates. In addition, full-range XPS spectra qualitatively revealed the presence of iodine on chalcopyrite surface. High resolution XPS spectra of the I 3d peaks after adsorption verified the chemical environment of iodine. The binding energies of 618.8 eV and 623.5 eV for I 3d5/2 peaks unveiled that the adsorption of iodide and iodate ions on copper-iron sulfide minerals was the result of formation of low solubility metal iodides precipitate. Also two I 3d peaks with low intensity around 618 eV and 630 eV might be related to the inorganic reduction of iodate to iodide by reducing S2- ion of chalcopyrite.

  17. Investigation of the electrokinetic properties of paraffin suspension. 2. In cationic and anionic surfactant solutions.

    PubMed

    Chibowski, Emil; Wiacek, Agnieszka; Holysz, Lucyna; Terpilowski, Konrad

    2005-08-16

    Electrical phenomena at nonionogenic hydrophobic surfaces (solid or liquid) in water, electrolyte, and/or surfactant solutions still attract research. In part 1 of this paper we described the electrokinetic behavior of paraffin wax suspension in water and electrolyte solutions (NaCl or LaCl3). On the basis of the latest data of water structure near hydrophobic surfaces it was concluded that immobilized water dipoles at the interface can play an essential role in the zeta potential formation. In this paper were investigated the zeta potentials of paraffin wax in cationic surfactants cetyltrimethylammonium bromide, C16H33(CH3)3NBr, and octadecyltrimethylammonium chloride, C18H37(CH3)3NCl, and anionic surfactant sodium dodecyl sulfate, C12H25SO4Na. Also changes in wettability of the paraffin surface due to the surfactant's adsorption were studied via wetting contact angle measurements and calculation of the surface free energy. It was concluded that at a low surfactant concentration (10(-6) M) the water dipole structure still contributes to the zeta potential, but at a higher one the zeta potential is determined by the surfactant molecules' adsorption. A special role of OH- ions is also clearly seen. Moreover, a functional relationship was found between the surface free energy of the surfactant-covered paraffin surface and the zeta potential.

  18. The 2Πg shape resonance of acetylene anion: an investigation with the RAC method

    NASA Astrophysics Data System (ADS)

    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.

  19. Fluorinated Dodecaphenylporphyrins: Synthetic and Electrochemical Studies Including the First Evidence of Intramolecular Electron Transfer Between an Fe(II) Porphyrin -Anion Radical and an Fe(I) Porphyrin

    SciTech Connect

    D'Souza, F.; Forsyth, T.P.; Fukuzumi, S.; Kadish, K.M.; Krattinger, B.; Lin, M.; Medforth, C.J.; Nakanishi, I.; Nurco, D.J.; Shelnutt, J.A.; Smith, K.M.; Van Caemelbecke, E.

    1998-10-19

    Dodecaphenylporphyrins with varying degrees of fluorination of the peripheral phenyl rings (FXDPPS) were synthesized as model compounds for studying electronic effects in nonplan~ porphyrins, and detailed electrochemical studies of the chloroiron(HI) complexes of these compounds were undertaken. The series of porphyrins, represented as FeDPPCl and as FeFXDPPCl where x = 4, 8 (two isomers), 12, 20,28 or 36, could be reversibly oxidized by two electrons in dichloromethane to give n-cation radicals and n-dications. All of the compounds investigated could also be reduced by three electrons in benzonitrile or pyridine. In benzonitrile, three reversible reductions were observed for the unfluorinated compound FeDPPC1, whereas the FeFXDPPCl complexes generally exhibited irreversible first and second reductions which were coupled to chemical reactions. The chemical reaction associated with the first reduction involved a loss of the chloride ion after generation of Fe FXDPPC1. The second chemical reaction involved a novel intramolecular electron transfer between the initially generated Fe(H) porphyrin n-anion radical and the final Fe(I) porphyrin reduction product. In pyridine, three reversible one electron reductions were observed with the second reduction affording stable Fe(II) porphyrin o - anion radicals for ail of the complexes investigated.

  20. Laser cooling of the OH(-) molecular anion in a theoretical investigation.

    PubMed

    Wan, Ming-Jie; Huang, Duo-Hui; Yu, You; Zhang, Yun-Guang

    2017-10-03

    The schemes for laser cooling of the OH(-) anion are proposed using an ab initio method. Scalar relativistic corrections are considered using the Douglas-Kroll Hamilton. Spin-orbit coupling (SOC) effects are taken into account at the MRCI+Q level. SOC effects play important roles in the transition properties of the OH(-) anion. Transition strengths for the transition of the OH(-) anion cannot be ignored. Large vibrational branching ratios for the and transitions are determined. Short spontaneous radiative lifetimes for the a(3)Π1 and A(1)Π1 states are also predicted for rapid laser cooling. The vibrational branching loss ratio to the intervening states a(3)Π0 and a(3)Π1 for the transition is small enough to enable the building of a laser cooling project. The three required laser wavelengths for the and transitions are all in the visible region. The results imply the probability of laser cooling of the OH(-) anion via both a spin-forbidden transition and a three-electronic-level transition.

  1. Photoelectron imaging and density-functional investigation of bismuth and lead anions solvated in ammonia clusters.

    PubMed

    Sobhy, Mohamed A; Casalenuovo, K; Reveles, J Ulises; Gupta, Ujjwal; Khanna, Shiv N; Castleman, A W

    2010-10-28

    We present the results of photoelectron velocity-map imaging experiments for the photodetachment of small negatively charged ammonia solvated Bi(n) and Pb(n) (n = 1, 2) clusters at 527 nm. The vertical detachment energies of the observed multiple electronic bands and their respective anisotropy parameters for the solvated Bi and Pb anions and clusters derived from the photoelectron images are reported. The electronic bands of Bi(NH(3))(n=1,2) are distinct from the Bi metal ion in exhibiting a perpendicular distribution whereas the electronic bands in Pb(NH(3))(n=1,2), unlike the Pb anion, show an isotropic distribution with respect to the laser polarization. Density-functional theory calculations with a generalized gradient approximation for the exchange-correlation potential were performed on these clusters to determine their atomic and electronic structures. Calculated geometries show a dramatic change between anionic and neutral ammonia solvated Bi and Pb species. Anionic clusters exhibit van der Waals interactions between the hydrogen atoms of ammonia and the metal core, where it was determined that the negative charge is localized. Neutral clusters, on the other hand, present a covalent bond between the nitrogen atom of ammonia and the metal core. Calculated binding energies show an enhancement in the bonding of the (NH(3))(2) dimer in the presence of the anionic Bi(1,2)(-) and Pb(1,2)(-) metal ions. This is rationalized by the electrostatic interaction between the negative charged metal core and the hydrogen atoms of the ammonia molecule.

  2. Quantum-chemical and electrochemical investigation of the electrochemical windows of halogenated carborate anions.

    PubMed

    Boeré, René T; Bolli, Christoph; Finze, Maik; Himmelspach, Alexander; Knapp, Carsten; Roemmele, Tracey L

    2013-01-28

    The range of electrochemical stability of a series of weakly coordinating halogenated (Hal=F, Cl, Br, I) 1-carba-closo-dodecaborate anions, [1-R-CB(11)X(5)Y(6)](-) (R=H, Me; X=H, Hal, Me; Y=Hal), has been established by using quantum chemical calculations and electrochemical methods. The structures of the neutral and dianionic radicals, as well as the anions, have been optimized by using DFT calculations at the PBE0/def2-TZVPP level. The calculated structures are in good agreement with existing experimental data and with previous calculations. Their gas-phase ionization energies and electron affinities were calculated based on their optimized structures and were compared with experimental (cyclic and square-wave) voltammetry data. Electrochemical oxidation was performed in MeCN at room temperature and in liquid sulfur dioxide at lower temperatures. All of the anions show a very high resistance to the onset of oxidation (2.15-2.85 V versus Fc(0/+)), with only a minor dependence of the oxidation potential on the different halogen substituents. In contrast, the reduction potentials in MeCN are strongly substituent dependent (-1.93 to -3.32 V versus Fc(0/+)). The calculated ionization energies and electron affinities correlate well with the experimental redox potentials, which provide important verification of the thermodynamic validity of the mostly irreversible redox processes that are observed for this series. The large electrochemical windows that are afforded by these anions indicate their suitability for electrochemical applications, for example, as supporting electrolytes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Vacuum-Deposited Porphyrin Protective Films on Graphite: Electrochemical Atomic Force Microscopy Investigation during Anion Intercalation.

    PubMed

    Yivlialin, Rossella; Bussetti, Gianlorenzo; Penconi, Marta; Bossi, Alberto; Ciccacci, Franco; Finazzi, Marco; Duò, Lamberto

    2017-02-01

    The development of graphene products promotes a renewed interest toward the use of graphite in addition to the historical one for its proven viability as battery electrode. However, when exposed to harsh conditions, the graphite surface ages in ways that still need to be fully characterized. In applications to batteries, to optimize the electrode performances in acid solutions, different surface functionalizations have been studied. Among them, aromatic molecules have been recently proposed. In this communication, we report on the protective effect exerted by a physical-vapor-deposited porphyrin layer. Metal-free tetra-phenyl-porphyrins were deposited on a highly oriented pyrolytic graphite crystal to study the modifications that occur during anion intercalation in graphite. The graphite electrode was plunged in an electrolyte solution of 1 M sulfuric acid and subjected to cyclic voltammetry. The results indicate that blister formation, the characteristic swelling of graphite surface induced by anion intercalation, is significantly perturbed by the porphyrin overlayer; the process is inhibited in those areas where the protective porphyrin film is present. We ascribe the inhibition of the anion intercalation to the protective porphyrin wetting layer.

  4. Vibrational investigations of guanine, thioguanine and their singly charged cations and anions

    NASA Astrophysics Data System (ADS)

    Singh, R.; Yadav, R. A.

    2017-01-01

    The complete vibrational studies have been done with help of quantum mechanics for the neutral Guanine (Gua) and Thioguanine (TGua) molecules and their singly charged cations and anions employing the B3LYP/6-311++G** method. Neutral Thioguanine and cations of Guanine and Thioguanine show planar structures and belong to Cs point group symmetry while the neutral Guanine and anions of Guanine and Thioguanine possess non-planar structure with C1 point group symmetry. Vibrational studies of ionic radicals of Gua and its thio- derivative are not available in literatures. Such extensive studies have been attempted for the first time. The normal modes of all the species have been assigned on the basis using potential energy distributions (PEDs) using GAR2PED software. The PEDs have also been calculated to make a conspicuous assignment as animation available in GaussView is not a guarantee for correct normal mode assignment. Charge transfer occurs in the molecule have been shown by the calculated highest occupied molecular orbital—lowest unoccupied molecular orbital (HOMO-LUMO) energies. The mapping of electron density iso-surface with electrostatic potential, has been carried out to get the information about the size, shape, charge density distribution and site of chemical reactivity of the molecule. The electronic properties HOMO and LUMO energies have been measured. The energy gap from HOMO to LUMO of the Gua is 5.0547 eV and TGua 4.0743 eV.

  5. Investigation on the interaction of Safranin T with anionic polyelectrolytes by spectrophotometric method

    NASA Astrophysics Data System (ADS)

    Fradj, Anouar Ben; Lafi, Ridha; Hamouda, Sofiane Ben; Gzara, Lassaad; Hamzaoui, Ahmed Hichem; Hafiane, Amor

    2014-10-01

    Understanding the role played by chemical additives such as NaCl salt, acid and Cetylpyridinium Chloride (CPC) surfactant on the interaction between dye and polyelectrolyte contributes to optimization of processes using polyelectrolytes in the removal of dye from aqueous solution. Herein we focus in the interaction between Safranin T, a cationic dye, with two anionic polyelectrolytes, poly(ammonium acrylate) and poly(acrylic acid) using spectrophotometric method and conductivity measurement. In aqueous solution, each of anionic polyelectrolytes forms a complex with the dye and induces a metachromasy indicated by the blue shift of the absorbance of the dye. The stoichiometry of complexes evaluated by the molar ratio method are 1:1 for Safranin T poly(ammonium acrylate) and 2:1 in the case of Safranin T poly(acrylic acid). The effect of additives on the stability of complexes has been studied by varying concentrations of the salt and the surfactant and pH of the solution. The thermodynamic parameters of interaction ΔG, ΔH and ΔS at different temperatures were evaluated to determine the stability constant of the complexes.

  6. Electronic structure of the diatomic VO anion: A combined photoelectron-imaging spectroscopic and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Cheng, Shi-Bo; Harmon, Christopher L.; Yang, Huan; Castleman, A. W.

    2016-12-01

    The electronic structure of the diatomic VO anion was explored by combining the photoelectron-imaging spectroscopy and high-level theoretical calculations. The electron affinity (EA) of VO is determined to be 1.244 ± 0.025 eV from the vibrationally resolved photoelectron spectrum acquired at 532 nm. The anisotropy parameter (β) for the EA defined peak is measured to be 1.59 ± 0.02, indicating that it is the 9σ electron attachment leading to the formation of the ground state of V O- . The present imaging experiment provides direct evidence that the ground state of V O- is X 3Σ- with a (3π ) 4(8σ ) 2(9σ ) 2(1δ ) 2 electron configuration, which resolves the significant discrepancy in previous experiment and theory. In addition, the molecular orbitals and bonding involved in the anionic VO cluster are also examined based on the present high-level theoretical calculations.

  7. Anions in Cometary Comae

    NASA Technical Reports Server (NTRS)

    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.

  8. Tetraalkylammonium salts of weakly coordinating aluminates: ionic liquids, materials for electrochemical applications and useful compounds for anion investigation.

    PubMed

    Raabe, Ines; Wagner, Katrin; Guttsche, Kristin; Wang, Mingkui; Grätzel, Michael; Santiso-Quiñones, Gustavo; Krossing, Ingo

    2009-01-01

    In this study, we investigated the tetraalkylammonium salts of the weakly coordinating fluorinated alkoxyaluminates [pftb](-) ([Al(O(C(CF(3))(3))(4)](-)), [hfip](-) ([Al(OC(H)(CF(3))(2))(4)](-)) and [hftb](-) ([Al(OC(CH(3))(CF(3))(2))(4)](-)) in order to obtain information on their undisturbed spectral and structural properties, as well as to study their electrochemical behavior (i.e., conductivities in non-polar solvents and electrochemical windows). Several of the compounds qualify as ionic liquids with melting points as low as 42 degrees C for [NBu(4)](+)[hfip](-). Simple and almost quantitative metathesis reactions yielding these materials in high purity were developed. These [NR(4)](+) salts serve as model compounds for undisturbed anions and their vibrational spectra--together with simulated spectra based on quantum chemical DFT calculations--were used for the clear assignment of the anion bands. Besides, the ion volumes of the anions (V(ion)([pftb](-)) = 0.736 nm(3), V(ion)([hftb](-)) = 0.658 nm(3), V(ion)([hfip](-)) = 0.577 nm(3)) and their decomposition pathways in the mass spectrometric measurements have been established. The salts are highly soluble in non-polar solvents (up to 1.09 mol L(-1) are possible for [NBu(4)](+)[hftb](-) in CH(2)Cl(2) and 0.41 mol L(-1) for [NBu(4)](+)[hfip](-) in CHCl(3)) and show higher molar conductivities if compared to [NBu(4)](+)[PF(6)](-). The electrochemical windows of CH(2)Cl(2), CH(3)CN and 1,2-F(2)C(6)H(4) using the [NBu(4)](+) aluminate electrolytes are up to +0.5 V/-0.7 V larger than those using the standard [NBu(4)](+)[PF(6)](-).

  9. Intercalation chemistry in a LDH system: anion exchange process and staging phenomenon investigated by means of time-resolved, in situ X-ray diffraction.

    PubMed

    Taviot-Guého, Christine; Feng, Yongjun; Faour, Azzam; Leroux, Fabrice

    2010-07-14

    stacking thickness during the anion exchange process but with no change of the in-plane coherent length, therefore no in-plane deformation of LDH host layers. Finally, the anion exchange properties of Zn(2)Cr-Cl/tartrate, investigated by means of EDXRD, show highly selective anion-exchange reactions, leading to the formation of new second-stage intermediates that cannot be prepared starting from the mono-intercalated Zn(2)Cr-Cl. This "Zn(2)Cr-Cl/tartrate approach" might constitute a new route for the synthesis of various mixed organic-inorganic anions-exchanged forms of LDH.

  10. Toward the microscopic identification of anions and cations at the ionic liquid|Ag(111) interface: a combined experimental and theoretical investigation.

    PubMed

    Buchner, Florian; Forster-Tonigold, Katrin; Uhl, Benedikt; Alwast, Dorothea; Wagner, Nadja; Farkhondeh, Hanieh; Gross, Axel; Behm, R Jürgen

    2013-09-24

    The interaction between an adsorbed 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMP][TFSA], ionic liquid (IL) layer and a Ag(111) substrate, under ultrahigh-vacuum conditions, was investigated in a combined experimental and theoretical approach, by high-resolution scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and dispersion-corrected density functional theory calculations (DFT-D). Most importantly, we succeeded in unambiguously identifying cations and anions in the adlayer by comparing experimental images with submolecular resolution and simulated STM images based on DFT calculations, and these findings are in perfect agreement with the 1:1 ratio of anions and cations adsorbed on the metal derived from XPS measurements. Different adlayer phases include a mobile 2D liquid phase at room temperature and two 2D solid phases at around 100 K, i.e., a 2D glass phase with short-range order and some residual, but very limited mobility and a long-range ordered 2D crystalline phase. The mobility in the different adlayer phases, including melting of the 2D crystalline phase, was evaluated by dynamic STM imaging. The DFT-D calculations show that the interaction with the substrate is composed of mainly van der Waals and weak electrostatic (dipole-induced dipole) interactions and that upon adsorption most of the charge remains at the IL, leading to attractive electrostatic interactions between the adsorbed species.

  11. Gas phase anion photoelectron spectroscopy and theoretical investigation of gold acetylide species

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Zhang, Wenjing; Xu, Xi-Ling; Yuan, Jinyun; Xu, Hong-Guang; Zheng, Weijun

    2017-05-01

    We conducted gas phase anion photoelectron spectroscopy and density functional theory studies on a number of gold acetylide species, such as AuC2H, AuC2Au, and Au2C2H. Based on the photoelectron spectra, the electron affinities of AuC2H, AuC2Au, and Au2C2H are measured to be 1.54(±0.04), 1.60(±0.08), and 4.23(±0.08) eV, respectively. The highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps of AuC2H and AuC2Au are measured to be about 2.62 and 2.48 eV, respectively. It is interesting that photoelectron spectra of AuC2H- and AuC2Au- display similar spectral features. The comparison of experimental and theoretical results confirms that the ground-state structures of AuC2H-, AuC2Au-, and their neutrals are all linear with Au—C≡C—H and Au—C≡C—Au configurations. The similar geometric structures, spectral features, HOMO-LUMO gaps, and chemical bonding between AuC2H-/0 and AuC2Au-/0 demonstrate that Au atom behaves like H atom in these species. The photoelectron spectrum of Au2C2H- shows that Au2C2H has a high electron affinity of 4.23(±0.08) eV, indicating Au2C2H is a superhalogen. Further, we found an unusual similarity between the terminal Au atom of Au2C2H- and the iodine atom of IAuC2H-.

  12. Anion order in perovskites: a group-theoretical analysis.

    PubMed

    Talanov, M V; Shirokov, V B; Talanov, V M

    2016-03-01

    Anion ordering in the structure of cubic perovskite has been investigated by the group-theoretical method. The possibility of the existence of 261 ordered low-symmetry structures, each with a unique space-group symmetry, is established. These results include five binary and 14 ternary anion superstructures. The 261 idealized anion-ordered perovskite structures are considered as aristotypes, giving rise to different derivatives. The structures of these derivatives are formed by tilting of BO6 octahedra, distortions caused by the cooperative Jahn-Teller effect and other physical effects. Some derivatives of aristotypes exist as real substances, and some as virtual ones. A classification of aristotypes of anion superstructures in perovskite is proposed: the AX class (the simultaneous ordering of A cations and anions in cubic perovskite structure), the BX class (the simultaneous ordering of B cations and anions) and the X class (the ordering of anions only in cubic perovskite structure). In most perovskites anion ordering is accompanied by cation ordering. Therefore, the main classes of anion order in perovskites are the AX and BX classes. The calculated structures of some anion superstructures are reported. Comparison of predictions and experimentally investigated anion superstructures shows coherency of theoretical and experimental results.

  13. Chiral anion exchangers applied to capillary electrochromatography enantioseparation of oppositely charged chiral analytes: investigation of stationary and mobile phase parameters.

    PubMed

    Lämmerhofer, M; Tobler, E; Lindner, W

    2000-07-28

    RSD values in the range of 5-10% for theoretical plate numbers and resolution, thus clearly establishing the reliability of the investigated anion-exchange type CEC enantioseparation methods.

  14. Investigation of Anion Effects in Ionic Liquid-Nano Hybrid Materials

    DTIC Science & Technology

    2006-06-23

    the gold have been prepared for the surface plasmon resonance ( SPR ) spectroscopy (Biocore 2000), and investigated the non-specific binding of a...imidazolium salt formed on the gold chip (Figure 1) provided by Biacore for the surface plasmon resonance ( SPR ) spectroscopy (Biocore 2000) upon soaking them...which used for surface plasmon resonance spectroscopy ( SPR ) study Our previous electrochemical study on SAM 1a clearly indicated that thiol

  15. Molecular anions of polydeprotonated naphthalenes: An investigation on the metastability and deprotonation energies using nuclear-charge stabilization method.

    PubMed

    Sangwan, Poonam; Vikas

    2016-01-28

    The dianions and trianions of doubly- and triply-deprotonated naphthalenes are investigated using density functional theory (DFT) computations employing hybrid, long-range, and dispersion corrected exchange-correlation functionals. The investigated polyanionic species are found to be metastable with negative electron affinity and are further treated using a nuclear-charge stabilization method. The tunneling lifetimes of these anionic species were estimated to be a few femtoseconds. Notably, the deprotonated energies (DPEs) of naphthalene leading to the formation of triply deprotonated trianions are observed to be affected by the metastability of the dianions and trianions. For the deprotonation of doubly deprotonated dianions, the DPE calculated using the improved methodology based on the stabilization method is found to be nearly 100 kcal/mol more than that computed using the conventional procedure. Though the various DFT approximations employed are in a good agreement for predicting the lifetimes of the metastable species but in the prediction of electron-affinities and deprotonation energies, the dispersion-corrected DFT-D3 significantly disagrees with the long-range corrected DFT methods employing cam-B3LYP and ωB97XD exchange-correlation functionals.

  16. Molecular anions of polydeprotonated naphthalenes: An investigation on the metastability and deprotonation energies using nuclear-charge stabilization method

    SciTech Connect

    Sangwan, Poonam; Vikas E-mail: qlabspu@yahoo.com

    2016-01-28

    The dianions and trianions of doubly- and triply-deprotonated naphthalenes are investigated using density functional theory (DFT) computations employing hybrid, long-range, and dispersion corrected exchange-correlation functionals. The investigated polyanionic species are found to be metastable with negative electron affinity and are further treated using a nuclear-charge stabilization method. The tunneling lifetimes of these anionic species were estimated to be a few femtoseconds. Notably, the deprotonated energies (DPEs) of naphthalene leading to the formation of triply deprotonated trianions are observed to be affected by the metastability of the dianions and trianions. For the deprotonation of doubly deprotonated dianions, the DPE calculated using the improved methodology based on the stabilization method is found to be nearly 100 kcal/mol more than that computed using the conventional procedure. Though the various DFT approximations employed are in a good agreement for predicting the lifetimes of the metastable species but in the prediction of electron-affinities and deprotonation energies, the dispersion-corrected DFT-D3 significantly disagrees with the long-range corrected DFT methods employing cam-B3LYP and ωB97XD exchange-correlation functionals.

  17. Spectroscopic investigations on the interaction of an anionic probe with nonionic micelles of Igepal surfactants in aqueous media

    NASA Astrophysics Data System (ADS)

    Moore, S. A.; Palepu, R. M.

    The behaviour of the anionic dye 8-anilino-1-napthalenesulfonic acid ammonium salt, or ANS, in aqueous solutions containing the Igepal series of polyoxyethylene nonionic surfactants was investigated using fluorescence spectroscopic technique. The interactions of the dye with the nonionic surfactants were examined in micellar media, to prevent dye aggregate formation and to ensure maximum dye and surfactant interaction. From the relative fluorescence enhancements, binding constants of the dye to the surfactant micelles and aggregation numbers of the micelles were determined. The aggregation numbers were also separately determined by static fluorescence quenching of pyrene by cetylpyridinium chloride in aqueous surfactant mixtures at a fixed concentration of surfactant, and compared with the value obtained from the present investigation of the interaction of the micelles with the ANS probe. The values of binding constants, micropolarity values sensed by pyrene and the Stern-Volmer constants for quenching of pyrene fluorescence by cetylpyridinium chloride were correlated with the number of ethylene oxide groups in the Igepal series.

  18. First-principles investigation on Rydberg and resonance excitations: A case study of the firefly luciferin anion

    SciTech Connect

    Noguchi, Yoshifumi Hiyama, Miyabi; Akiyama, Hidefumi; Koga, Nobuaki

    2014-07-28

    The optical properties of an isolated firefly luciferin anion are investigated by using first-principles calculations, employing the many-body perturbation theory to take into account the excitonic effect. The calculated photoabsorption spectra are compared with the results obtained using the time-dependent density functional theory (TDDFT) employing the localized atomic orbital (AO) basis sets and a recent experiment in vacuum. The present method well reproduces the line shape at the photon energy corresponding to the Rydberg and resonance excitations but overestimates the peak positions by about 0.5 eV. However, the TDDFT-calculated positions of some peaks are closer to those of the experiment. We also investigate the basis set dependency in describing the free electron states above vacuum level and the excitons involving the transitions to the free electron states and conclude that AO-only basis sets are inaccurate for free electron states and the use of a plane wave basis set is required.

  19. Complex anion inclusion compounds: flexible anion-exchange materials.

    PubMed

    Williams, Edward R; Leithall, Rebecca M; Raja, Robert; Weller, Mark T

    2013-01-11

    Copper chloropyrophosphate frameworks have been synthesised with a wide variety of complex inorganic anions trapped in a large, flexible, one-dimensional pore, with anions including chloride, bromide, phosphate and the complex metal halo-anions PtCl(4)(2-), PdBr(4)(2-), CuCl(4)(2-) and AuCl(4)(-).

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

    SciTech Connect

    Bowman-James, Kristen

    2004-12-01

    This project have focuses on the basic chemical aspects of anion receptor design of functional pH independent systems, with the ultimate goal of targeting the selective binding of sulfate, as well as design of separations strategies for selective and efficient removal of targeted anions. Key findings include: (1) the first synthetic sulfate-selective anion-binding agents; (2) simple, structure-based methods for modifying the intrinsic anion selectivity of a given class of anion receptors; and (3) the first system capable of extracting sulfate anion from acidic, nitrate-containing aqueous media. Areas probed during the last funding period include: the design, synthesis, and physical and structural characterization of receptors and investigation of anion and dual ion pair extraction using lipophilic amide receptors for anion binding. A new collaboration has been added to the project in addition to the one with Dr. Bruce Moyer at Oak Ridge National Laboratory, with Professor Jonathan Sessler at the University of Texas at Austin.

  1. Ab initio investigation of sulfur monofluoride and its singly charged cation and anion in their ground electronic state

    NASA Astrophysics Data System (ADS)

    Song, Li; Shan-Jun, Chen; Yan, Chen; Peng, Chen

    2016-03-01

    The SF radical and its singly charged cation and anion, SF+ and SF-, have been investigated on the MRCI/aug-cc-pVXZ (X = Q, 5, 6) levels of theory with Davidson correction. Both the core-valence correlation and the relativistic effect are considered. The extrapolating to the complete basis set (CBS) limit is adopted to remove the basis set truncation error. Geometrical parameters, potential energy curves (PECs), vibrational energy levels, spectroscopic constants, ionization potentials, and electron affinities of the ground electronic state for all these species are obtained. The information with respect to molecular characteristics of the SFn (n = -1, 0, +1) systems derived in this work will help to extend our knowledge and to guide further experimental or theoretical researches. Project supported by the National Natural Science Foundation of China (Grant Nos. 11304023 and 11447172), the Young and Middle-Aged Talent of Education Burea of Hubei Province, China (Grant No. Q20151307), and the Yangtze Youth Talents Fund of Yangtze University, China (Grant No. 2015cqr21).

  2. Structures of Al{sub n}, its anions and cations up to n=34: A theoretical investigation

    SciTech Connect

    Drebov, Nedko; Ahlrichs, Reinhart

    2010-04-28

    A systematic density functional study has been performed for neutral and singly charged clusters of aluminum with up to 34 atoms. A thorough search for global minimum structures has been carried out for Al{sub n} employing genetic algorithm and basin-hopping procedures. For Al{sub n} this confirms results of previous investigations up to n=22; new global minima have been located for n=23-31, 33. Structures for singly charged cations and anions have been obtained by reoptimization of the pool of 40 low-energy structures of the neutral clusters. The global minima of charged and neutral clusters are always low-spin states with the possible exception of a triplet state of Al{sub 28}, which is isoenergetic with a singlet. The cluster structures are mostly quite irregular and do not resemble fractions of the fcc bulk phase. High symmetries are found only for the global minimum of Al{sub 23} and the triplet state of Al{sub 28}.

  3. Photodetachment of Lanthanide Oxide Anions

    NASA Astrophysics Data System (ADS)

    Covington, A. M.; Emmons, E. D.; Kraus, R. G.; Thompson, J. S.; Calabrese, D.; Davis, V. T.

    2007-06-01

    Laser photodetached electron spectroscopy (LPES) has been used to study the structure and collision properties of lanthanide oxide anions including LaOn^- and CeOn^-. Preliminary photoelectron spectra from these anions will be presented along with ion beam production data from these and other lanthanide oxide anions.

  4. a Quantum Chemical Investigation of the Stability and Chemistry of the Anions of CO and H_2CO in Astrophysical Ices

    NASA Astrophysics Data System (ADS)

    Chen, L.; Woon, D. E.

    2011-06-01

    Electrons may either be deposited on interstellar icy grain mantles from the gas phase, or they may be produced in situ via photoionization. It is energetically favorable for electrons to bind to species in the ice to form anions. Similarly, anions may be formed within icy grain mantles from chemical processes such as proton transfer from an acid to a base. To understand the fate of electrons in astrophysical ices and the potential impact of anions on gas-grain chemistry, we explored the behavior of two common and important interstellar molecules -- CO and formaldehyde (H_2CO) -- when they interact with an electron in ice. Neither CO nor H_2CO bind an electron in the gas phase. In astrophysical ices, however, quantum chemical calculations indicate that the anions of CO and H_2CO are stabilized by interacting with the polarized field provided by water ice and are bound with respect to CO and H_2CO. We then investigated whether CO^- and H_2CO^- are stable with respect to subsequent chemical reactions and sought to identify vibrational spectroscopic features that might be useful for experimentalists to identify these anions in the laboratory. In our theoretical investigations reported here, we studied CO^- + nH_2O and H_2CO^- + mH_2O in clusters containing from 2 to 17 water molecules using B3LYP/6-31+G** and MP2/6-31+G** calculations. The calculations show that in smaller water clusters, both CO^- and H_2CO^- are stabilized by water molecules. However, in larger clusters, both anions can undergo barrierless reactions in which a proton is transferred from a nearby water molecule, forming radicals such as HCO or H_2COH and hydroxide anion (OH^-). Since HCO and H_2COH are precursors to H_2CO and CH_3OH, electron-induced anion chemistry in ices may contribute to the observed abundances of important astromolecules. In addition to the structures and energetics of these clusters, we will also provide theoretical predictions of spectroscopic features that might be detected

  5. Benchmark values of chemical potential and chemical hardness for atoms and atomic ions (including unstable anions) from the energies of isoelectronic series.

    PubMed

    Cárdenas, Carlos; Heidar-Zadeh, Farnaz; Ayers, Paul W

    2016-09-14

    We present benchmark values for the electronic chemical potential and chemical hardness from reference data for ionization potentials and electron affinities. In cases where the energies needed to compute these quantities are not available, we estimate the ionization potential of the metastable (di)anions by extrapolation along the isoelectronic series, taking care to ensure that the extrapolated data satisfy reasonable intuitive rules to the maximum possible extent. We also propose suitable values for the chemical potential and chemical hardness of zero-electron species. Because the values we report are faithful to the trends in accurate data on atomic energies, we believe that our proposed values for the chemical potential and chemical hardness are ideally suited to conceptual studies of chemical trends across the periodic table. The critical nuclear charge (Z critical) of the isoelectronic series with 2 < N < 96 has also been reported for the first time.

  6. Investigating the Effects of Guest-Host Interactions on the Properties of Anion-Exchanged Mg-Al Hydrotalcites

    NASA Astrophysics Data System (ADS)

    Malherbe, François; Besse, Jean-Pierre

    2000-12-01

    A starting [Mg-Al-Cl] LDH, prepared by coprecipitation, was further anion-exchanged to incorporate a variety of anions in the interlayer domain: (Fe(CN)6)3-, (P2O7)4-, (V2O7)4-, (CrO4)2-, and (Cr2O7)2-. The resulting materials were fully characterized using classical techniques like XRPD, FTIR, TGA/DTA, and BET, and their structural modifications studied as a function of calcination temperatures. Under mild calcination, only the oxo-anions were shown to interact strongly with the host matrix. This resulted in a systematic shrinkage of the interlamellar domain, with a negative impact on the surface properties. However, intercalation of oxo-anions proved to be beneficial to thermal stability, the lamellar structure being maintained up to 400°C in the case of the dichromate intercalated [Mg-Al]. A thorough analysis of the FTIR spectra, revealing an evolution in the symmetry of some oxo-anions, confirmed the occurrence of a grafting process. Furthermore, the permanent character of the pillars was evidenced through unsuccessful rehydration and back-exchange reactions.

  7. Spectroscopic, colorimetric and theoretical investigation of salicylidene hydrazine based reduced Schiff base and its application towards biologically important anions.

    PubMed

    Jana, Sankar; Dalapati, Sasanka; Alam, Md Akhtarul; Guchhait, Nikhil

    2012-06-15

    A reduced Schiff base anionic receptor 1 [N,N'-bis-(2-hydroxy-5-nitro-benzyl)hydrazine] has been synthesized, characterized and reported as a selective chromogenic receptor for fluoride, acetate and phosphate anions over the other tested anions such as chloride, bromide, iodide and hydrogensulphite. Colorimetric naked-eye detection and UV-vis absorption spectroscopic techniques were used to distinguish the recognition behaviours towards various anions. The receptor-anion complexation mainly occurs via hydrogen bonding interactions which facile to generate the charge transfer band in the UV-vis spectra and cause large bathochromic shift as well as naked-eye colour change. Complexation stoichiometry, binding constant and free energy change due to complex formation were determined from Benesi-Hildebrand plot. The binding constant and the free energy change values are well interactive for spontaneous complexation. The experimental results have been correlated with the theoretical calculations using B3LYP hybrid functional and 6-311++G(d,p) basis set for both the receptor and complex by Density Functional Theory (DFT) method.

  8. 25 CFR 12.32 - Do minimum employment standards include a background investigation?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... investigation? 12.32 Section 12.32 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER... of a Federal officer performing the same duties. The background investigations of applicants and... standards include a background investigation? Law enforcement authority is only entrusted to...

  9. Investigation on enhanced chemiluminescence reaction systems with bis(hydrogenperiodato) argentate(III) complex anion for fluoroquinolones synthetic antibiotics.

    PubMed

    Sun, Hanwen; Chen, Peiyun; Wang, Fei; Wen, Haifang

    2009-07-15

    A novel chemiluminescence (CL) reaction system with bis(hydrogenperiodato) argentate(III) complex anion (Ag(III) complex, [Ag(HIO(6))(2)](5-)), for the first time, is developed for the determination of lomefloxacin (LMFX), enrofloxacin (ENLX) and pefloxacin (PFLX). The possible CL emission mechanism was discussed by comparing the fluorescence emission with CL spectra. The CL conditions of [Ag(HIO(6))(2)](5-)-H(2)SO(4)-LMFX/ENLX/PFLX systems were investigated and optimized. Under the optimized experimental conditions, the CL intensity is proportional to the concentration of the drugs in the range 0.2994-36.80x10(-7)g mL(-1) for LMFX, 4.00-30.0x10(-7)g mL(-1) for ENLX and 1.54-27.64x10(-7)g mL(-1) for PFLX. The limit of detection (s/n=3) was 9.1x10(-9)g mL(-1) for LMFX, 3.1x10(-9)g mL(-1) for ENLX and 4.4x10(-9)g mL(-1) for PFLX. The recovery of LMFX, ENLX and PELX from the spiked pharmaceutical preparations was in the range of 92.3-105% with the RSDs of 0.5-2.7%. For urine, serum and milk samples the recoveries of the three drugs were in the range of 85.1-107% for LMFX with the RSDs of 2.3-3.4%. 80.2-112% for ENLX with the RSDs of 1.4-2.8%, and 87.8-114% for PFLX with the RSDs of 1.6-2.7%. The proposed method was applied successfully to the determination of these compounds in real samples.

  10. Construction of an ultrasensitive non-enzymatic sensor to investigate the dynamic process of superoxide anion release from living cells.

    PubMed

    Wei, Hongwei; Shang, Tianyi; Wu, Tiaodi; Liu, Guoan; Ding, Lan; Liu, Xiuhui

    2017-08-24

    In this work, a novel non-enzymatic superoxide anion (O2•(-)) sensor was constructed based on Ag nanoparticles (NPs) / poly (amidoamine) (PAMAM) dendrimers and used to investigate the dynamic process of O2•(-) release from living cells. The AgNPs/PAMAM nanohybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The fabricated electrode exhibited excellent catalytic activity toward the reaction of O2•(-) with a super low detection limit (LOD) of 2.530 × 10(-13)M (S/N = 3) and wide linear range of 8 orders of magnitude. It could fulfill the requirement of real-time measurement O2•(-) released from living cells. Furthermore, zymosan was chosen as the stimulant to induce O2•(-) generation from cancer cells (rat adrenal medulla pheochromocytoma cell (PC12)). The electrochemical experiment results indicated that the levels of intracellular O2•(-) depended on the amount of Zymosan. A large amount of O2•(-) generated in the living cells by added heavy stimulant could damage cells seriously. More importantly, a vitro simulation experiment confirmed the role of superoxide dismutase (SOD) for the first time because it could maintain the O2•(-) concentration at a normal physiological range. These findings are of great significance for evaluating the metabolic processes of O2•(-) in the biological system, and this work has the tremendous potential application in clinical diagnostics to assess oxidative stress. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. 78 FR 47410 - Certain Wireless Devices, Including Mobile Phones and Tablets Institution of Investigation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-05

    ... COMMISSION Certain Wireless Devices, Including Mobile Phones and Tablets Institution of Investigation AGENCY... within the United States after importation of certain wireless devices, including mobile phones and... wireless devices, including mobile phones and tablets by reason of infringement of one or more of claims 1...

  12. Separators for Li-Ion and Li-Metal Battery Including Ionic Liquid Based Electrolytes Based on the TFSI− and FSI− Anions

    PubMed Central

    Kirchhöfer, Marija; von Zamory, Jan; Paillard, Elie; Passerini, Stefano

    2014-01-01

    The characterization of separators for Li-ion or Li-metal batteries incorporating hydrophobic ionic liquid electrolytes is reported herein. Ionic liquids made of N-butyl-N-methylpyrrolidinium (PYR14+) or N-methoxyethyl-N-methylpyrrolidinium (PYR12O1+), paired with bis(trifluoromethanesulfonyl)imide (TFSI−) or bis(fluorosulfonyl)imide (FSI−) anions, were tested in combination with separators having different chemistries and morphologies in terms of wetting behavior, Gurley and McMullin number, as well as Li/(Separator + Electrolyte) interfacial properties. It is shown that non-functionalized microporous polyolefin separators are poorly wetted by FSI−-based electrolytes (contrary to TFSI−-based electrolytes), while the ceramic coated separator Separion® allows good wetting with all electrolytes. Furthermore, by comparing the lithium solid electrolyte interphase (SEI) resistance evolution at open circuit and during cycling, depending on separator morphologies and chemistries, it is possible to propose a scale for SEI forming properties in the order: PYR12O1FSI > PYR14FSI > PYR14TFSI > PYR12O1TFSI. Finally, the impact the separator morphology is evidenced by the SEI resistance evolution and by comparing Li electrodes cycled using separators with two different morphologies. PMID:25153637

  13. Studies of Oxide Anions

    DTIC Science & Technology

    1991-06-01

    oxide and metal hydroxide anions and related clusters of species including ones comprised of tungsten, tantalum , molybdenum and niobium . After...molybdenum, tantalum and niobium were produced. For the case of molybdenum, we observed oxides from MoO3 - to Mo3Of-, for tantalum , TaO4 - to Ta5O 16- and...of Nb. Analogous to the niobium case, all three tantalum oxide anions lead to the same four sequential products. The results show that whenever there

  14. 77 FR 24514 - Certain Consumer Electronics, Including Mobile Phones and Tablets; Institution of Investigation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-24

    ... COMMISSION Certain Consumer Electronics, Including Mobile Phones and Tablets; Institution of Investigation... consumer electronics, including mobile phones and tablets, by reason of infringement of certain claims of U... importation, or the sale within the United States after importation of certain consumer electronics,...

  15. An ONIOM investigation on anion recognition of alkali-metal complexes with diurea calix[4]arene receptor.

    PubMed

    Chanapiwat, Pornpan; Ruangpornvisuti, Vithaya

    2012-06-01

    The ONIOM(B3LYP/6-31G(d):AM1) optimized structures of complexes of diurea calix[4]arene receptor (L) with alkali metals Li(+), Na(+) and K(+) and their complexes with halide ions F(-), Cl(-), Br(-), oxygen-containing anions HCO(3)(-), HSO(4)(-) and CH(3)COO(-) ions were obtained. Binding energies and thermodynamic properties of complex receptors LiL(+), NaL(+) and KL(+) with these anions were determined. The binding stabilities according to binding energies of LiL(+), NaL(+) and KL(+) associated with anions computed either at the ZPVE-corrected ONIOM(B3LYP/6-31G(d):AM1) or BSSE-corrected B3LYP/6-31 + G(d,p)//ONIOM(B3LYP/6-31G(d):AM1) are in the same order: F(-) > CH(3)COO(-) ≈ HCO(3)(-) > Br(-) ≈ HSO(4)(-) ≈ Cl(-). All the receptors LiL(+), NaL(+) and KL(+) were found to be selective toward fluoride ion.

  16. Investigation of the acidic properties of ZrO{sub 2} modified by SO{sub 4}{sup 2{minus}} anions

    SciTech Connect

    Kustov, L.M.; Kazansky, V.B.; Figueras, F.; Tichit, D.

    1994-11-01

    Zirconium dioxide modified by sulfate anions was investigated using diffuse reflectance IR spectroscopy. It was found that this modification enhanced the strength of both Bronsted acid sites (terminal or bridging ZrOH groups) and Lewis acid sites (low-coordinate Zr ions). However, Bronsted acid sites with enhanced strength appeared to be weaker than bridging OH groups in zeolites. Modification also created protons with a new environment. These protons were assumed to form multicenter bonds with oxygen atoms of SO{sub 4}{sup 2{minus}} anions or with neighboring basic oxygen and to possess acidic properties, comparable to those of protons in zeolites. Low-temperature ethylene and cyclopropane oligomerization and H-D exchange were shown to proceed on sulfated zirconia, presumably with participation of such sites. 25 refs., 11 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. The separation of platinum, palladium and gold from silicate rocks by the anion exchange separation of chloro complexes after a sodium peroxide fusion: an investigation of low recoveries.

    PubMed

    Enzweiler, J; Potts, P J

    1995-10-01

    A series of experiments was undertaken to measure the recovery efficiency of platinum, palladium and gold from silicate rocks using a sodium peroxide fusion followed by anion exchange separation of the analytes as chloro complexes. Results obtained by graphite furnace atomic absorption spectrometric analysis of standard solutions prepared in dilute HCl or HCl-acidified sodium peroxide solution showed that recoveries were near quantitative. However, when standard solutions were added to an alkaline sodium peroxide solution, which was then acidified, low results were obtained for platinum and gold (46% and 76% respectively). Low and variable results were also obtained when standard solutions were added to a peridotite sample that had been dissolved by the state procedure, and in the analysis of the South African Bureau of Standards certified reference material, SARM 7. Various experiments were undertaken to investigate these low recoveries, but the reason proposed here is the formation of hydroxychloro compounds in alkaline solution which are not, on acidification with HCl, converted quantitatively to the chloro complex necessary for quantitative anion exchange separation. It is concluded that a sodium peroxide fusion followed by an anion-exchange separation does not appear to form the basis of a successful technique for the determination of platinum, palladium and gold in silicate rocks.

  19. Modeling, rate-limiting step investigation, and enhancement of the direct bio-regeneration of perchlorate laden anion-exchange resin.

    PubMed

    Wang, Chao; Lippincott, Lee; Yoon, In-Ho; Meng, Xiaoguang

    2009-01-01

    Anion-exchange with high perchlorate affinity resins is one of the most promising technologies for removing low levels of perchlorate. However, the traditional brine desorption technique is difficult and costly for regeneration of this type of resin. Previously, a direct bio-regeneration method by contacting the spent high perchlorate affinity resin with the perchlorate-reducing bacteria was proved feasible. This research is a further study of that method. Firstly, a direct bio-regeneration process model, based on the physicochemical and biological fundamentals, was developed and calibrated with experimental data. Thereafter, the rate-limiting step in regeneration of the high perchlorate affinity resin was investigated. Methods to enhance the regeneration efficiency were developed. The results indicated that the calibrated model well described the regeneration process. It thus might provide useful insights into the regeneration system. The results also demonstrated that the perchlorate desorption from the loaded resin could be the rate-limiting step. Addition of proper amount of counter anions such as chloride and sulfate improved the regeneration efficiency because these anions could promote both the extent and rate of perchlorate desorption from the loaded resin. These findings aided us in achieving good and efficient regeneration of high perchlorate affinity resins like the A-530E and SR-7 resins. The findings also suggested that the application of bacteria that could efficiently reduce perchlorate in highly saline solution would make the method more promising for the regeneration of high perchlorate affinity resins.

  20. Nuclear magnetic resonance studies on the rotational and translational motions of ionic liquids composed of 1-ethyl-3-methylimidazolium cation and bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts.

    PubMed

    Hayamizu, Kikuko; Tsuzuki, Seiji; Seki, Shiro; Umebayashi, Yasuhiro

    2011-08-28

    Room temperature ionic liquids (ILs) are stable liquids composed of anions and cations. 1-ethyl-3-methyl-imidazolium (EMIm, EMI) is a popular and important cation that produces thermally stable ILs with various anions. In this study two amide-type anions, bis(trifluoro-methanesulfonyl)amide [N(SO(2)CF(3))(2), TFSA, TFSI, NTf(2), or Tf(2)N] and bis(fluorosulfonyl)amide [(N(SO(2)F)(2), FSA, or FSI] were investigated by multinuclear NMR spectroscopy. In addition to EMIm-TFSA and EMIm-FSA, lithium-salt-doped binary systems were prepared (EMIm-TFSA-Li and EMIm-FSA-Li). The spin-lattice relaxation times (T(1)) were measured by (1)H, (19)F, and (7)Li NMR spectroscopy and the correlation times of (1)H NMR, τ(c)(EMIm) (8 × 10(-10) to 3 × 10(-11) s) for the librational molecular motion of EMIm and those of (7)Li NMR, τ(c)(Li) (5 × 10(-9) to 2 × 10(-10) s) for a lithium jump were evaluated in the temperature range between 253 and 353 K. We found that the bulk viscosity (η) versus τ(c)(EMIm) and cation diffusion coefficient D(EMIm) versus the rate 1/τ(c)(EMIm) have good relationships. Similarly, linear relations were obtained for the η versus τ(c)(Li) and the lithium diffusion coefficient D(Li) versus the rate 1∕τ(c)(Li). The mean one-jump distances of Li were calculated from τ(c)(Li) and D(Li). The experimental values for the diffusion coefficients, ionic conductivity, viscosity, and density in our previous paper were analyzed by the Stokes-Einstein, Nernst-Einstein, and Stokes-Einstein-Debye equations for the neat and binary ILs to clarify the physicochemical properties and mobility of individual ions. The deviations from the classical equations are discussed.

  1. Studies on the translational and rotational motions of ionic liquids composed of N-methyl-N-propyl-pyrrolidinium (P13) cation and bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts.

    PubMed

    Hayamizu, Kikuko; Tsuzuki, Seiji; Seki, Shiro; Fujii, Kenta; Suenaga, Masahiko; Umebayashi, Yasuhiro

    2010-11-21

    Room-temperature ionic liquids (RTIL, IL) are stable liquids composed of anions and cations. N-methyl-N-propyl-pyrrolidinium (P(13), Py(13), PYR(13), or mppy) is an important cation and produces stable ILs with various anions. In this study two amide-type anions, bis(trifluoromethanesulfonyl)amide [N(SO(2)CF(3))(2), TFSA, TFSI, NTf(2), or Tf(2)N] and bis(fluorosulfonyl)amide [N(SO(2)F)(2), FSA, or FSI], were investigated. In addition to P(13)-TFSA and P(13)-FSA, lithium salt doped samples were prepared (P(13)-TFSA-Li and P(13)-FSA-Li). The individual ion diffusion coefficients (D) and spin-lattice relaxation times (T(1)) were measured by (1)H, (19)F, and (7)Li NMR. At the same time, the ionic conductivity (σ), viscosity (η), and density (ρ) were measured over a wide temperature range. The van der Waals volumes of P(13), TFSA, FSA, Li(TFSA)(2), and Li(FSA)(3) were estimated by molecular orbital calculations. The experimental values obtained in this study were analyzed by the classical Stokes-Einstein, Nernst-Einstein (NE), and Stokes-Einstein-Debye equations and Walden plots were also made for the neat and binary ILs to clarify physical and mobile properties of individual ions. From the temperature-dependent velocity correlation coefficients for neat P(13)-TFSA and P(13)-FSA, the NE parameter 1-ξ was evaluated. The ionicity (electrochemical molar conductivity divided by the NE conductivity from NMR) and the 1-ξ had exactly the same values. The rotational and translational motions of P(13) and jump of a lithium ion are also discussed.

  2. Studies on the translational and rotational motions of ionic liquids composed of N-methyl-N-propyl-pyrrolidinium (P13) cation and bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts

    NASA Astrophysics Data System (ADS)

    Hayamizu, Kikuko; Tsuzuki, Seiji; Seki, Shiro; Fujii, Kenta; Suenaga, Masahiko; Umebayashi, Yasuhiro

    2010-11-01

    Room-temperature ionic liquids (RTIL, IL) are stable liquids composed of anions and cations. N-methyl-N-propyl-pyrrolidinium (P13, Py13, PYR13, or mppy) is an important cation and produces stable ILs with various anions. In this study two amide-type anions, bis(trifluoromethanesulfonyl)amide [N(SO2CF3)2, TFSA, TFSI, NTf2, or Tf2N] and bis(fluorosulfonyl)amide [N(SO2F)2, FSA, or FSI], were investigated. In addition to P13-TFSA and P13-FSA, lithium salt doped samples were prepared (P13-TFSA-Li and P13-FSA-Li). The individual ion diffusion coefficients (D) and spin-lattice relaxation times (T1) were measured by H1, F19, and L7i NMR. At the same time, the ionic conductivity (σ), viscosity (η), and density (ρ) were measured over a wide temperature range. The van der Waals volumes of P13, TFSA, FSA, Li(TFSA)2, and Li(FSA)3 were estimated by molecular orbital calculations. The experimental values obtained in this study were analyzed by the classical Stokes-Einstein, Nernst-Einstein (NE), and Stokes-Einstein-Debye equations and Walden plots were also made for the neat and binary ILs to clarify physical and mobile properties of individual ions. From the temperature-dependent velocity correlation coefficients for neat P13-TFSA and P13-FSA, the NE parameter 1-ξ was evaluated. The ionicity (electrochemical molar conductivity divided by the NE conductivity from NMR) and the 1-ξ had exactly the same values. The rotational and translational motions of P13 and jump of a lithium ion are also discussed.

  3. Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

    NASA Astrophysics Data System (ADS)

    Bhaskaran-Nair, Kiran; Valiev, Marat; Deng, S. H. M.; Shelton, William A.; Kowalski, Karol; Wang, Xue-Bin

    2015-12-01

    The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI-), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  4. Probing microhydration effect on the electronic structure of the GFP chromophore anion: Photoelectron spectroscopy and theoretical investigations

    SciTech Connect

    Bhaskaran-Nair, Kiran; Shelton, William A.; Valiev, Marat; Kowalski, Karol; Deng, S. H. M.; Wang, Xue-Bin

    2015-12-14

    The photophysics of the Green Fluorescent Protein (GFP) chromophore is critically dependent on its local structure and on its environment. Despite extensive experimental and computational studies, there remain many open questions regarding the key fundamental variables that govern this process. One outstanding problem is the role of autoionization as a possible relaxation pathway of the excited state under different environmental conditions. This issue is considered in our work through combined experimental and theoretical studies of microsolvated clusters of the deprotonated p-hydroxybenzylidene-2,3-dimethylimidazolinone anion (HBDI{sup −}), an analog of the GFP chromophore. Through selective generation of microsolvated structures of predetermined size and subsequent analysis of experimental photoelectron spectra by high level ab initio methods, we are able to precisely identify the structure of the system, establish the accuracy of theoretical data, and provide reliable description of auto-ionization process as a function of hydrogen-bonding environment. Our study clearly illustrates the first few water molecules progressively stabilize the excited state of the chromophore anion against the autodetached neutral state, which should be an important trait for crystallographic water molecules in GFPs that has not been fully explored to date.

  5. Experimental Investigation of a Supersonic Boundary Layer Including Favorable Pressure Gradient Effects

    DTIC Science & Technology

    2011-07-21

    United States Government. EXPERIMENTAL INVESTIGATION OF A SUPERSONIC BOUNDARY LAYER INCLUDING FAVORABLE PRESSURE GRADIENT EFFECTS THESIS Presented to...flow to be disturbed from its original state . Aside from providing a non-intrusive method of measurement, LDV has the advantage of measuring the...providing some useful test of turbulence modeling. 4. Well-defined experimental boundary conditions: All incoming conditions (especially the state of

  6. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

    PubMed

    Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-15

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Vishvakarma, Vijay K.; Kumari, Kamlesh; Patel, Rajan; Dixit, V. S.; Singh, Prashant; Mehrotra, Gopal K.; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-01

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation.

  8. Analytical model for investigation of interior noise characteristics in aircraft with multiple propellers including synchrophasing

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1986-01-01

    A simplified analytical model of transmission of noise into the interior of propeller-driven aircraft has been developed. The analysis includes directivity and relative phase effects of the propeller noise sources, and leads to a closed form solution for the coupled motion between the interior and exterior fields via the shell (fuselage) vibrational response. Various situations commonly encountered in considering sound transmission into aircraft fuselages are investigated analytically and the results obtained are compared to measurements in real aircraft. In general the model has proved successful in identifying basic mechanisms behind noise transmission phenomena.

  9. Putting anion-π interactions into perspective.

    PubMed

    Frontera, Antonio; Gamez, Patrick; Mascal, Mark; Mooibroek, Tiddo J; Reedijk, Jan

    2011-10-04

    Supramolecular chemistry is a field of scientific exploration that probes the relationship between molecular structure and function. It is the chemistry of the noncovalent bond, which forms the basis of highly specific recognition, transport, and regulation events that actuate biological processes. The classic design principles of supramolecular chemistry include strong, directional interactions like hydrogen bonding, halogen bonding, and cation-π complexation, as well as less directional forces like ion pairing, π-π, solvophobic, and van der Waals potentials. In recent years, the anion-π interaction (an attractive force between an electron-deficient aromatic π system and an anion) has been recognized as a hitherto unexplored noncovalent bond, the nature of which has been interpreted through both experimental and theoretical investigations. The design of selective anion receptors and channels based on this interaction represent important advances in the field of supramolecular chemistry. The objectives of this Review are 1) to discuss current thinking on the nature of this interaction, 2) to survey key experimental work in which anion-π bonding is demonstrated, and 3) to provide insights into the directional nature of anion-π contact in X-ray crystal structures.

  10. Mechanistic Investigation of Solvent Extraction Based on Anion-Functionalized Ionic Liquids for Selective Separation of Rare-Earth Ions

    SciTech Connect

    Sun, Xiaoqi; Luo, Huimin; Dai, Sheng

    2013-01-01

    In this study, solvation has been found to be a dominant mechanism in a comprehensive ionic liquid based extraction system for rare earth elements (REEs). Trioctylmethylammonium di(2-ethylhexyl)phosphate ([TOMA][DEHP]), an ionic-liquid extractant, was used in 1-alkyl-3-methylimidizolium bis[(trifluoromethyl)sulfonyl]imide ([Cnmim][NTf2], n = 4, 6, 8, 10) and 1-alkyl-3-methylimidizolium bis(perfluoroethanesulfonyl)imide ([Cnmim][BETI], n = 4, 6, 8, 10) for the separation of REEs. Surprisingly, a very similar extraction behavior was observed even as the carbon chain length on the ionic-liquid (IL) cation increased from butyl (C4) to hexyl (C6), to octyl (C8), to decyl (C10). This behavior is in sharp contrast to that exhibited by the conventional neutral extractants, whose extraction efficiencies are strongly dependent on the hydrophobicity of IL cations. Furthermore, the addition of IL cations ([Cnmim]+) or IL anions ([NTf2]- or [BETI]-) to the aqueous phase had little effect on the extraction behavior of the above extraction system, ruling out the strong involvement of the ion-exchange mechanism associated with traditional IL-based extraction systems. Results showed that the extractabilities and selectivities of REEs using [TOMA][DEHP] in [C10mim][NTf2]/[BETI] are several orders of magnitude better than those achieved using conventional organic solvent, diisopropylbenzene (DIPB). This study highlights the potential of developing a comprehensive IL-based extraction strategy for REEs separations.

  11. NMR investigations of dinuclear, single-anion bridged copper(II) metallacycles: structure and antiferromagnetic behavior in solution.

    PubMed

    Reger, Daniel L; Pascui, Andrea E; Pellechia, Perry J; Ozarowski, Andrew

    2013-11-04

    The nuclear magnetic resonance (NMR) spectra of single-anion bridged, dinuclear copper(II) metallacycles [Cu2(μ-X)(μ-L)2](A)3 (L(m) = m-bis[bis(1-pyrazolyl)methyl]benzene: X = F(-), A = BF4(-); X = Cl(-), OH(-), A = ClO4(-); L(m)* = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene: X = CN(-), F(-), Cl(-), OH(-), Br(-), A = ClO4(-)) have relatively sharp (1)H and (13)C NMR resonances with small hyperfine shifts due to the strong antiferromagnetic superexchange interactions between the two S = 1/2 metal centers. The complete assignments of these spectra, except X = CN(-), have been made through a series of NMR experiments: (1)H-(1)H COSY, (1)H-(13)C HSQC, (1)H-(13)C HMBC, T1 measurements and variable-temperature (1)H NMR. The T1 measurements accurately determine the Cu···H distances in these molecules. In solution, the temperature dependence of the chemical shifts correlate with the population of the paramagnetic triplet (S = 1) and diamagnetic singlet (S = 0) states. This correlation allows the determination of antiferromagnetic exchange coupling constants, -J (Ĥ = -JŜ1Ŝ2), in solution for the L(m) compounds 338(F(-)), 460(Cl(-)), 542(OH(-)), for the L(m)* compounds 128(CN(-)), 329(F(-)), 717(Cl(-)), 823(OH(-)), and 944(Br(-)) cm(-1), respectively. These values are of similar magnitudes to those previously measured in the solid state (-Jsolid = 365, 536, 555, 160, 340, 720, 808, and 945 cm(-1), respectively). This method of using NMR to determine -J values in solution is an accurate and convenient method for complexes with strong antiferromagnetic superexchange interactions. In addition, the similarity between the solution and solid-state -J values of these complexes confirms the information gained from the T1 measurements: the structures are similar in the two states.

  12. Resonant spectra of quadrupolar anions

    NASA Astrophysics Data System (ADS)

    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.

  13. Ion exchange polymers for anion separations

    DOEpatents

    Jarvinen, Gordon D.; Marsh, S. Fredric; Bartsch, Richard A.

    1997-01-01

    Anion exchange resins including at least two positively charged sites and a ell-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

  14. Ion exchange polymers for anion separations

    DOEpatents

    Jarvinen, G.D.; Marsh, S.F.; Bartsch, R.A.

    1997-09-23

    Anion exchange resins including at least two positively charged sites and a well-defined spacing between the positive sites are provided together with a process of removing anions or anionic metal complexes from aqueous solutions by use of such resins. The resins can be substituted poly(vinylpyridine) and substituted polystyrene.

  15. LANDSAT-4 Science Investigations Summary, Including December 1983 Workshop Results. Volume 2

    NASA Technical Reports Server (NTRS)

    Barker, J. L. (Editor)

    1984-01-01

    A series of brief summaries of the results of individual investigations of LANDSAT 4 image data characteristics are presented. Topics are divided into MSS and TM investigations, and applications of the imaging techniques. Radiometric and geometric accuracy are emphasized.

  16. Thermodynamic and Spectroscopic Investigation of Interactions between Reactive Red 223 and Reactive Orange 122 Anionic Dyes and Cetyltrimethyl Ammonium Bromide (CTAB) Cationic Surfactant in Aqueous Solution

    PubMed Central

    Irfan, Muhammad; Usman, Muhammad; Mansha, Asim; Rasool, Nasir; Ibrahim, Muhammad; Rana, Usman Ali; Siddiq, Mohammad; Zia-Ul-Haq, Muhammad; Jaafar, Hawa Z. E.; Khan, Salah Ud-Din

    2014-01-01

    The present study describes the conductometric and spectroscopic study of the interaction of reactive anionic dyes, namely, reactive red 223 and reactive orange 122 with the cationic surfactant cetyltrimethyl ammonium bromide (CTAB). In a systematic investigation, the electrical conductivity data was used to calculate various thermodynamic parameters such as free energy (ΔG), enthalpy (ΔH), and the entropy (ΔS) of solubilization. The trend of change in these thermodynamic quantities indicates toward the entropy driven solubilization process. Moreover, the results from spectroscopic data reveal high degree of solubilization, with strong interactions observed in the cases of both dyes and the CTAB. The spontaneous nature of solubilization and binding was evident from the observed negative values of free energies (ΔGp and ΔGb). PMID:25243216

  17. Dynamics of dipole- and valence bound anions in iodide-adenine binary complexes: A time-resolved photoelectron imaging and quantum mechanical investigation

    SciTech Connect

    Stephansen, Anne B.; King, Sarah B.; Li, Wei-Li; Kunin, Alice; Yokoi, Yuki; Minoshima, Yusuke; Takayanagi, Toshiyuki; Neumark, Daniel M.

    2015-09-14

    Dipole bound (DB) and valence bound (VB) anions of binary iodide-adenine complexes have been studied using one-color and time-resolved photoelectron imaging at excitation energies near the vertical detachment energy. The experiments are complemented by quantum chemical calculations. One-color spectra show evidence for two adenine tautomers, the canonical, biologically relevant A9 tautomer and the A3 tautomer. In the UV-pump/IR-probe time-resolved experiments, transient adenine anions can be formed by electron transfer from the iodide. These experiments show signals from both DB and VB states of adenine anions formed on femto- and picosecond time scales, respectively. Analysis of the spectra and comparison with calculations suggest that while both the A9 and A3 tautomers contribute to the DB signal, only the DB state of the A3 tautomer undergoes a transition to the VB anion. The VB anion of A9 is higher in energy than both the DB anion and the neutral, and the VB anion is therefore not accessible through the DB state. Experimental evidence of the metastable A9 VB anion is instead observed as a shape resonance in the one-color photoelectron spectra, as a result of UV absorption by A9 and subsequent electron transfer from iodide into the empty π-orbital. In contrast, the iodide-A3 complex constitutes an excellent example of how DB states can act as doorway state for VB anion formation when the VB state is energetically available.

  18. Dynamics of dipole- and valence bound anions in iodide-adenine binary complexes: A time-resolved photoelectron imaging and quantum mechanical investigation.

    PubMed

    Stephansen, Anne B; King, Sarah B; Yokoi, Yuki; Minoshima, Yusuke; Li, Wei-Li; Kunin, Alice; Takayanagi, Toshiyuki; Neumark, Daniel M

    2015-09-14

    Dipole bound (DB) and valence bound (VB) anions of binary iodide-adenine complexes have been studied using one-color and time-resolved photoelectron imaging at excitation energies near the vertical detachment energy. The experiments are complemented by quantum chemical calculations. One-color spectra show evidence for two adenine tautomers, the canonical, biologically relevant A9 tautomer and the A3 tautomer. In the UV-pump/IR-probe time-resolved experiments, transient adenine anions can be formed by electron transfer from the iodide. These experiments show signals from both DB and VB states of adenine anions formed on femto- and picosecond time scales, respectively. Analysis of the spectra and comparison with calculations suggest that while both the A9 and A3 tautomers contribute to the DB signal, only the DB state of the A3 tautomer undergoes a transition to the VB anion. The VB anion of A9 is higher in energy than both the DB anion and the neutral, and the VB anion is therefore not accessible through the DB state. Experimental evidence of the metastable A9 VB anion is instead observed as a shape resonance in the one-color photoelectron spectra, as a result of UV absorption by A9 and subsequent electron transfer from iodide into the empty π-orbital. In contrast, the iodide-A3 complex constitutes an excellent example of how DB states can act as doorway state for VB anion formation when the VB state is energetically available.

  19. Correlation of lysozyme activity and stability in the presence of Hofmeister series anions.

    PubMed

    Garajová, Katarína; Balogová, Anna; Dušeková, Eva; Sedláková, Dagmar; Sedlák, Erik; Varhač, Rastislav

    2017-03-01

    Enzymatic activity and stability of lysozyme in the presence of salts have been studied by fluorescence spectroscopy and differential scanning calorimetry, respectively. The effect of sodium salts of sulfate, acetate, chloride, bromide, thiocyanate, and perchlorate on lysozyme properties depends on anion concentration as well as on position of anion in the Hofmeister series. Kosmotropic anions (sulfate and acetate) increase stability and activate the enzyme while chaotropic anions (bromide, thiocyanate and perchlorate) including chloride decrease stability and inhibits the enzyme activity. Strong correlation between stability and activity of lysozyme suggest the interdependence of these enzyme properties in the presence of salts. The fact that the properties of lysozyme correlate with partition coefficients of anions at hydrocarbon surface clearly indicates that Hofmeister effect of anions is mediated by their interactions with nonpolar parts of the enzyme surface despite its high positive net charge at studied conditions. The efficiency of the anions in affecting both activity and stability of lysozyme also correlates with other anion-related parameters most notably with polarizability of monovalent anions. The presented work points to a critical role of interaction of anions with nonpolar protein surface for the Hofmeister effect. Moreover, the simultaneous investigation of protein stability and activity, in the relation with the Hofmeister effect, provides important information regarding stability/rigidity of enzyme structure for its catalytic activity. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 25 CFR 12.32 - Do minimum employment standards include a background investigation?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... possessing adequate education and/or experience, training, aptitude, and high moral character. All Indian... of a Federal officer performing the same duties. The background investigations of applicants and...

  1. 25 CFR 12.32 - Do minimum employment standards include a background investigation?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... possessing adequate education and/or experience, training, aptitude, and high moral character. All Indian... of a Federal officer performing the same duties. The background investigations of applicants and...

  2. Anion conductance selectivity mechanism of the CFTR chloride channel.

    PubMed

    Linsdell, Paul

    2016-04-01

    All ion channels are able to discriminate between substrate ions to some extent, a process that involves specific interactions between permeant anions and the so-called selectivity filter within the channel pore. In the cystic fibrosis transmembrane conductance regulator (CFTR) anion-selective channel, both anion relative permeability and anion relative conductance are dependent on anion free energy of hydration--anions that are relatively easily dehydrated tend to show both high permeability and low conductance. In the present work, patch clamp recording was used to investigate the relative conductance of different anions in CFTR, and the effect of mutations within the channel pore. In constitutively-active E1371Q-CFTR channels, the anion conductance sequence was Cl(-) > NO3(-) > Br(-) > formate > SCN(-) > I(-). A mutation that disrupts anion binding in the inner vestibule of the pore (K95Q) disrupted anion conductance selectivity, such that anions with different permeabilities showed almost indistinguishable conductances. Conversely, a mutation at the putative narrowest pore region that is known to disrupt anion permeability selectivity (F337A) had minimal effects on anion relative conductance. Ion competition experiments confirmed that relatively tight binding of permeant anions resulted in relatively low conductance. These results suggest that the relative affinity of ion binding in the inner vestibule of the pore controls the relative conductance of different permeant anions in CFTR, and that the pore has two physically distinct anion selectivity filters that act in series to control anion conductance selectivity and anion permeability selectivity respectively.

  3. LANDSAT-4 Science Investigations Summary, Including December 1983 Workshop Results, Volume 1

    NASA Technical Reports Server (NTRS)

    Barker, J. L. (Editor)

    1984-01-01

    A general overview of the LANDSAT 4 system with emphasis on the Thematic Mapper (TM) is presented. A variety of topics on the design, calibration, capabilities, and image processing techniques of the TM sensor are discussed in detail. The comparison of TM data with other MSS data is also investigated.

  4. Wind-tunnel investigation of an externally blown flap STOL transport model including and investigation of wall effects

    NASA Technical Reports Server (NTRS)

    Gentry, G. L., Jr.

    1974-01-01

    A wind-tunnel investigation was conducted in the Langley V/STOL tunnel and in a scaled version of the Ames 40- by 80-foot tunnel test section installed as a liner in the Langley V/STOL tunnel to determine the effect of test-section size on aerodynamic characteristics of the model. The model investigated was a swept-wing, jet-powered, externally blown flap (EBF) STOL transport configuration with a leading-edge slat and triple-slotted flaps. The model was an 0.1645-scale model of a 11.58-meter (38.0-ft) span model designed for tests in a 40- by 80-foot tunnel. The data compare the aerodynamic characteristics of the model with and without the tunnel liner installed. Data are presented as a function of thrust coefficient over an angle-of-attack range of 0 deg to 25 deg. A thrust-coefficient range up to approximately 4.0 was simulated, most ot the tests being conducted at a free-stream dynamic pressure of 814 Newtons/sq m (17 lb sq ft). The data are presented with a minimum of analysis.

  5. Cognitive Functioning after Medial Frontal Lobe Damage Including the Anterior Cingulate Cortex: A Preliminary Investigation

    ERIC Educational Resources Information Center

    Baird, Amee; Dewar, Bonnie-Kate; Critchley, Hugo; Gilbert, Sam J.; Dolan, Raymond J.; Cipolotti, Lisa

    2006-01-01

    Two patients with medial frontal lobe damage involving the anterior cingulate cortex (ACC) performed a range of cognitive tasks, including tests of executive function and anterior attention. Both patients lesions extended beyond the ACC, therefore caution needs to be exerted in ascribing observed deficits to the ACC alone. Patient performance was…

  6. Cognitive Functioning after Medial Frontal Lobe Damage Including the Anterior Cingulate Cortex: A Preliminary Investigation

    ERIC Educational Resources Information Center

    Baird, Amee; Dewar, Bonnie-Kate; Critchley, Hugo; Gilbert, Sam J.; Dolan, Raymond J.; Cipolotti, Lisa

    2006-01-01

    Two patients with medial frontal lobe damage involving the anterior cingulate cortex (ACC) performed a range of cognitive tasks, including tests of executive function and anterior attention. Both patients lesions extended beyond the ACC, therefore caution needs to be exerted in ascribing observed deficits to the ACC alone. Patient performance was…

  7. Investigation of Techno-Stress Levels of Teachers Who Were Included in Technology Integration Processes

    ERIC Educational Resources Information Center

    Çoklar, Ahmet Naci; Efilti, Erkan; Sahin, Yusef Levent; Akçay, Arif

    2016-01-01

    Techno-stress is defined as a modern adaptation disorder resulting from the failure in coping with new technologies in a healthy way. Techno-stress affects many occupational groups, including teachers. FATIH project and many other previous studies conducted in Turkey in recent years have necessitated the use of technology for teachers. The present…

  8. Anion transport with halogen bonds.

    PubMed

    Jentzsch, Andreas Vargas; Matile, Stefan

    2015-01-01

    This review covers the application of halogen bonds to transport anions across lipid bilayer membranes. The introduction provides a brief description of biological and synthetic transport systems. Emphasis is on examples that explore interactions beyond the coordination with lone pairs or hydrogen bonds for the recognition of cations and anions, particularly cation-π and anion-π interactions, and on structural motifs that are relevant for transport studies with halogen bonds. Section 2 summarizes the use of macrocyclic scaffolds to achieve transport with halogen bonds, focusing on cyclic arrays of halogen-bond donors of different strengths on top of calixarene scaffolds. This section also introduces methods to study anion binding in solution and anion transport in fluorogenic vesicles. In Sect. 3, transport studies with monomeric halogen bond-donors are summarized. This includes the smallest possible organic anion transporter, trifluoroiodomethane, a gas that can be bubbled through a suspension of vesicles to turn on transport. Anion transport with a gas nicely illustrates the power of halogen bonds for anion transport. Like hydrogen bonds, they are directional and strong, but compared to hydrogen-bond donors, halogen-bond donors are more lipophilic. Section 3 also offers a concise introduction to the measurement of ion selectivity in fluorogenic vesicles and conductance experiments in planar bilayer membranes. Section 4 introduces the formal unrolling of cyclic scaffolds into linear scaffolds that can span lipid bilayers. As privileged transmembrane scaffolds, the importance of hydrophobically matching fluorescent p-oligophenyl rods is fully confirmed. The first formal synthetic ion channel that operates by cooperative multiion hopping along transmembrane halogen-bonding cascades is described. Compared to homologs for anion-π interactions, transport with halogen bonds is clearly more powerful.

  9. Investigation of the electronic structures of organolanthanide sandwich complex anions by photoelectron spectroscopy: 4f orbital contribution in the metal-ligand interaction.

    PubMed

    Hosoya, Natsuki; Yada, Keizo; Masuda, Tomohide; Nakajo, Erika; Yabushita, Satoshi; Nakajima, Atsushi

    2014-05-01

    The electronic structures of lanthanide (Ln) ions sandwiched between 1,3,5,7-cyclooctatetraene (COT), Ln(COT)2(-), have been investigated by anion photoelectron spectroscopy. Complexes of 12 Ln atoms were investigated (excluding promethium (Pm), europium (Eu), and ytterbium (Yb)). The 213 nm photoelectron (PE) spectra of Ln(COT)2(-) exhibit two peaks assignable to the highest occupied molecular orbital (HOMO; e2u) and the next HOMO (HOMO-1; e2g) approximately at 2.6 and 3.6 eV, respectively, and their energy gap increases as the central metal atom progresses from lanthanum (La) to lutetium (Lu). Since lanthanide contraction shortens the distance between the Ln atom and the COT ligands, the widening energy gap represents the destabilization of the e2u orbital as well as the stabilization of the e2g orbital. Evidence for 4f orbital contribution in the metal-ligand interaction has been revealed by the Ln atom dependence in which the same e2u orbital symmetry enables an interaction between the 4f orbital of Ln atoms and the π orbital of COT.

  10. Impact of Expanding ELISA Screening in DUID Investigations to Include Carisoprodol/Meprobamate and Zolpidem.

    PubMed

    Lu, Aileen; Scott, Karen S; Chan-Hosokawa, Aya; Logan, Barry K

    2017-03-01

    In 2013, the National Safety Council's Alcohol Drugs and Impairment Division added zolpidem and carisoprodol and its metabolite meprobamate to the list of Tier 1 drugs that should be tested for in all suspected drug impaired driving and motor vehicle fatality investigations. We describe the validation of an enzyme linked immunosorbent assays (ELISA) for both drugs in whole blood, and the utilization of the ELISA to assess their positivity in a sample of 322 suspected impaired driving cases that was retrospectively screened using the validated assays. The occurrence of carisoprodol/meprobamate was found to be 1.2%, and for zolpidem, 1.6%. In addition, we analyzed a large dataset (n = 1,672) of Driving Under the Influence of Drugs (DUID) test results from a laboratory performing high volume DUID testing to assess the frequency of detection of both drugs after implementing the expanded NSC scope. Carisoprodol or meprobamate were found positive in 5.9% (n = 99) of these samples, while zolpidem was found positive in 5.3% (n = 89) in drivers who in many cases had been found to be negative for other drugs. Carisoprodol and zolpidem are both potent CNS depressants and are appropriate additions to the recommended NSC scope of testing. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Environmental swabs as a tool in norovirus outbreak investigation, including outbreaks on cruise ships.

    PubMed

    Boxman, Ingeborg L A; Dijkman, Remco; te Loeke, Nathalie A J M; Hägele, Geke; Tilburg, Jeroen J H C; Vennema, Harry; Koopmans, Marion

    2009-01-01

    In this study, we investigated whether environmental swabs can be used to demonstrate the presence of norovirus in outbreak settings. First, a procedure was set up based on viral RNA extraction using guanidium isothiocyanate buffer and binding of nucleic acids to silica. Subsequently, environmental swabs were taken at 23 Dutch restaurants and four cruise ships involved in outbreaks of gastroenteritis. Outbreaks were selected based on clinical symptoms consistent with viral gastroenteritis and time between consumption of suspected food and onset of clinical symptoms (>12 h). Norovirus RNA was demonstrated by real-time reverse transcriptase PCR in 51 of 86 (59%) clinical specimens from 12 of 14 outbreaks (86%), in 13 of 90 (14%) food specimens from 4 of 18 outbreaks (22%), and in 48 of 119 (40%) swab specimens taken from 14 of 27 outbreaks (52%). Positive swab samples agreed with positive clinical samples in seven outbreaks, showing identical sequences. Furthermore, norovirus was detected on swabs taken from kitchen and bathroom surfaces in five outbreaks in which no clinical samples were collected and two outbreaks with negative fecal samples. The detection rate was highest for outbreaks associated with catered meals and lowest for restaurant-associated outbreaks. The use of environmental swabs may be a useful tool in addition to testing of food and clinical specimens, particularlywhen viral RNA is detected on surfaces used for food preparation.

  12. Cognitive functioning after medial frontal lobe damage including the anterior cingulate cortex: a preliminary investigation.

    PubMed

    Baird, Amee; Dewar, Bonnie-Kate; Critchley, Hugo; Gilbert, Sam J; Dolan, Raymond J; Cipolotti, Lisa

    2006-03-01

    Two patients with medial frontal lobe damage involving the anterior cingulate cortex (ACC) performed a range of cognitive tasks, including tests of executive function and anterior attention. Both patients lesions extended beyond the ACC, therefore caution needs to be exerted in ascribing observed deficits to the ACC alone. Patient performance was compared with age and education matched healthy controls. Both patients showed intact intellectual, memory, and language abilities. No clear-cut abnormalities were noted in visuoperceptual functions. Speed of information processing was mildly reduced only in Patient 2 (bilateral ACC lesion). The patients demonstrated weak or impaired performance only on selective executive function tests. Performance on anterior attention tasks was satisfactory. We tentatively suggest that our findings are inconsistent with anterior attention theories of ACC function based on neuroimaging findings. We propose that the data may imply that the ACC does not have a central role in cognition. We speculate that our findings may be compatible with the view that the ACC integrates cognitive processing with autonomic functioning to guide behaviour.

  13. 25 CFR 900.196 - Do covered services include the conduct of clinical studies and investigations and the provision...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... studies and investigations and the provision of emergency services, including the operation of emergency...-DETERMINATION AND EDUCATION ASSISTANCE ACT Federal Tort Claims Act Coverage General Provisions Medical-Related Claims § 900.196 Do covered services include the conduct of clinical studies and investigations and the...

  14. Paternal postnatal depression in Japan: an investigation of correlated factors including relationship with a partner.

    PubMed

    Nishimura, Akiko; Fujita, Yuichi; Katsuta, Mayumi; Ishihara, Aya; Ohashi, Kazutomo

    2015-05-31

    A negative effect of paternal depression on child development has been revealed in several previous studies. The aims of this study were to examine the prevalence and relevant factors associated with paternal postnatal depression at four months postpartum, including age, part-time work or unemployment, experience of visiting a medical institution due to a mental health problem, economic anxiety, unexpected pregnancy, pregnancy with infertility treatment, first child, partner's depression, and lower marital relationship satisfaction. We distributed 2032 self-report questionnaires to couples (one mother and one father) with a 4-month old infant between January and April 2013. Data from 807 couples (39.7 %) were analyzed. Depressive symptoms were measured with the Edinburgh Postnatal Depression Scale (EPDS). In order to clarify the factors related with paternal depression, a logistic regression analysis was conducted. One hundred and ten fathers (13.6 %) and 83 mothers (10.3 %) were depressed. According to the logistic regression analysis, paternal depression was positively associated with partner's depression (adjusted odds ratio (AOR) 1.91, 95 % confidence interval (CI) 1.05-3.47), and negatively with marital relationship satisfaction (AOR 0.83, 95 % CI 0.77-0.89). History of infertility treatment (AOR 2.37, 95 % CI 1.32-4.24), experience of visiting a medical institution due to a mental health problem (AOR 4.56, 95 % CI 2.06-10.08), and economic anxiety (AOR 2.15, 95 % CI 1.34-3.45) were also correlated with paternal depression. This study showed that the prevalence of paternal depression at four months after childbirth was 13.6 % in Japan. The presence of partner's depression and low marital relationship satisfaction were significantly correlated with paternal postpartum depression, suggesting that health professionals need to pay attention to the mental status of both fathers and mothers, and to their relationship.

  15. Computational Investigation and Validation of Twin-Tail Buffet Response Including Dynamics and Control

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.

    1998-01-01

    Multidisciplinary tools for prediction of single rectangular-tail buffet are extended to single swept-back-tail buffet in transonic-speed flow, and multidisciplinary tools for prediction and control of twin-tail buffet are developed and presented. The configuration model consists of a sharp-edged delta wing with single or twin tails that are oriented normal to the wing surface. The tails are treated as cantilevered beams fixed at the root and allowed to oscillate in both bending and torsion. This complex multidisciplinary problem is solved sequentially using three sets of equations on a dynamic single or multi-block grid structure. The first set is the unsteady, compressible, Reynolds-averaged Navier-Stokes equations which are used for obtaining the flow field vector and the aerodynamic loads on the tails. The Navier-Stokes equations are solved accurately in time using the implicit, upwind, flux-difference splitting, finite volume scheme. The second set is the coupled bending and torsion aeroelastic equations of cantilevered beams which are used for obtaining the bending and torsion deflections of the tails. The aeroelastic equations'are solved accurately in time using, a fifth-order-accurate Runge-Kutta scheme. The third set is the grid-displacement equations and the rigid-body dynamics equations, which are used for updating the grid coordinates due to the tail deflections and rigid-body motions. The tail-buffet phenomenon is predicted for highly-swept, single vertical tail placed at the plane of geometric symmetry, and for highly-swept, vertical twin tails placed at three different spanwise separation distances. The investigation demonstrates the effects of structural inertial coupling and uncoupling of the bending and torsion modes of vibration, spanwise positions of the twin-tail, angle of attack, and pitching and rolling dynamic motions of the configuration model on the tail buffet loading and response. The fundamental issue of twin-tail buffet alleviation is

  16. Experimental Investigation of Cross-Flow Axis Marine Hydrokinetic Turbines, Including Effects of Waves and Turbulence

    NASA Astrophysics Data System (ADS)

    Wosnik, M.; Bachant, P.

    2011-12-01

    A new test bed for Marine Hydrokinetic (MHK) turbines at the Center for Ocean Renewable Energy at the University of New Hampshire (UNH-CORE) was used to evaluate the performance of different cross-flow axis hydrokinetic turbines, and investigate the effects of waves and turbulence on these devices. The test bed was designed and built to operate in the UNH tow and wave tank, which has a cross section of 3.67m (width) x 2.44m (depth). In the present configuration, tow speeds of up to 3 m/s can be achieved for smaller turbine models, and up to 1.5 m/s for large turbine models with low gear ratio. It features a flap style wave maker at one end that is capable of producing waves with 1-5 s periods up to 0.4 m wave height. Turbine thrust (drag) and mechanical power output (torque, angular velocity) were measured at tow speeds of 0.6-1.5 m/s for two cross-flow axis MHK turbines: a Gorlov Helical Turbine (GHT) and a Lucid spherical turbine (LST). Both were provided by Lucid Energy Technologies, LLP, and have frontal areas of 1.3 (GHT) and 1.0 (LST) square meters, respectively. GHT performance was also measured in progressive waves of various periods, grid turbulence, and in the wake of a cylinder, installed upstream at various cross-stream locations. Overall, the GHT performs with higher power and thrust (drag) coefficients than the LST. A 2nd law efficiency, or kinetic exergy efficiency, was defined to calculate what fraction of the kinetic energy removed from the flow is converted to usable shaft work by each turbine. The exergy efficiency varies with tip speed ratio but approaches 90% for the optimum operating conditions for each turbine. The fraction of kinetic energy removed from the fluid that is not converted to shaft work is redistributed into turbulent kinetic energy in the wake. Quantifying the kinetic energy flowing out of the turbine is important for modeling of environmental transport processes and for predicting performance when turbines are used in arrays

  17. The effect of anions on the electrochemical properties of polyaniline for supercapacitors.

    PubMed

    Xing, Ji; Liao, Maoying; Zhang, Chi; Yin, Min; Li, Dongdong; Song, Ye

    2017-05-31

    To investigate the effect of anions on the electrochemical properties of polyaniline (PANI) for supercapacitors, electrochemical performance tests of PANI with different dopant anions were carried out in the corresponding acid solutions by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods. In particular, ionic fluxes and solvent molecules involved in redox processes can be analyzed by the electrochemical quartz crystal microbalance (EQCM) technique and discriminated by simultaneously recording cyclic voltammograms and mass changes during redox switching. The emeraldine base (EB) form of PANI prepared in a protonic acid with bigger anions can be easily doped by a protonic acid with smaller anions, and conversely, PANI-EB is hard to be doped. The anodic reversal potential of potentiodynamic cycling heavily influences the electrochemical stability of PANI. High anodic potentials result in PANI degradation. Its supercapacitive properties including specific capacitance, power density and cycling stability are strongly dependent upon the type of dopant anion. PANI with the dopant anions of oxalic acid has the highest specific capacitance and the best cycling stability among the used acids. The diffusion coefficient of anions plays a key role in determining power density. PANI films with organic dopant anions exhibit better cycling stability than their inorganic counterparts. It is believed that the hydrolysis of PANI facilitated by the additional water molecules accompanied by dopant anions into and out of the PANI matrix is a key factor responsible for the cycling instability.

  18. Hemibonding of hydroxyl radical and halide anion in aqueous solution.

    PubMed

    Yamaguchi, Makoto

    2011-12-29

    Molecular geometries and properties of the possible reaction products between the hydroxyl radical and the halide anions in aqueous solution were investigated. The formation of two-center three-electron bonding (hemibonding) between the hydroxyl radical and halide anions (Cl, Br, I) was examined by density functional theory (DFT) calculation with a range-separated hybrid (RSH) exchange-correlation functional. The long-range corrected hybrid functional (LC-ωPBE), which have given quantitatively satisfactory results for odd electron systems and excited states, was examined by test calculations for dihalogen radical anions (X(2)(-); X = Cl, Br, I) and hydroxyl radical-water clusters. Equilibrium geometries with hemibonding between the hydroxyl radical and halide anions were located by including four hydrogen-bonded water molecules. Excitation energies and oscillator strengths of σ-σ* transitions calculated by the time-dependent DFT method showed good agreement with observed values. Calculated values of the free energy of reaction on the formation of hydroxyl halide radical anion from the hydroxyl radical and halide anion were endothermic for chloride but exothermic for bromide and iodide, which is consistent with experimental values of equilibrium constants.

  19. Mixed Anion Heterostructure Materials

    DTIC Science & Technology

    2004-10-01

    data presented Sb(g) Sb(ads) Sb(s) Kads D (1) (2)Very low + GaAs no reaction ( 3 ) kexch 33 for As2 which indicates that the...Kads D (1) (2) ( 3 ) Anion Exchange kexch (4) Isoelectronic AsSb formation Favoured by As4 +As GaAsySb1-y + Sby(s) GaSb1-y + AsSby(s) +As kiso (5...experiment implemented for this investigation provided a basis for modeling the P(g) P(ads) P(s) + GaAs Kads D (1) (2) ( 3 ) kexch (4) +P GaPyAs1-y

  20. Analysis of free and total myo-inositol in foods, feeds, and infant formula by high-performance anion exchange chromatography with pulsed amperometric detection, including a novel total extraction using microwave-assisted acid hydrolysis and enzymatic treatment.

    PubMed

    Ellingson, David; Pritchard, Ted; Foy, Pamela; King, Kathryn; Mitchell, Barbara; Austad, John; Winters, Doug; Sullivan, Darryl

    2012-01-01

    A method for the analysis of free and total myo-inositol in foods, feeds, and infant formulas has been developed and validated using high-performance anion exchange chromatography with pulsed amperometric detection. The option of a free myo-inositol determination or a complete total myo-inositol determination from main bound sources can be achieved. These sources include phytates, lower'phosphorylated forms, and phosphatidylinositol. This approach gives the option for subtraction of myo-inositol from nonbioavailable sources when it is quantified using other methods if a total bioavailable myo-inositol result is desired for nutritional labeling of a product. The free analysis was validated in a milk-based infant formula, giving RSD(R) of 2.29% and RSD, of 2.06%. A mean recovery of 97.9% was achieved from various spike levels of myo-inositol. Certified National Institute of Standards and Technology reference material verified the method's compatibility and specificity. Two different total analyses were validated in a soy-based infant formula and compared. One technique involved using a conventional acid hydrolysis with autoclave incubation for 6 h, while the other used a novel technique of microwave-assisted acid hydrolysis with enzymatic treatment that can minimize extraction to 1 day. The autoclave analysis had RSD(R) of 2.08% and RSDr of 1.55%, along with a mean spike recovery of 102.1% at various myo-inositol spike levels. The microwave/enzyme total analysis had RSD(R) of 4.34% and RSD, of 4.70%, along with a mean spike recovery of 104.2% at various spike levels of myo-inositol. Main sources of myo-inositol including phytic acid and phosphatidylinositol were tested with both total analyses. Mean recoveries of phytic acid and phosphatidylinositol through the autoclave total analysis were 90.4 and 98.3%, respectively. Mean spike recoveries for these same sources in soy- based infant formula through the microwave/enzyme total analysis were 97.2 and 96

  1. Anion Gap Blood Test

    MedlinePlus

    ... Why do I need an anion gap blood test? Your health care provider may have ordered an anion gap blood ... which is a blood test. During a blood test, a health care professional uses a small needle to take a ...

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

    NASA Astrophysics Data System (ADS)

    Wang, Lai-Sheng

    2015-07-01

    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.

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

    SciTech Connect

    Wang, Lai-Sheng

    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.

  4. Modeling Carbon Chain Anions in L1527

    NASA Astrophysics Data System (ADS)

    Harada, Nanase; Herbst, Eric

    2008-09-01

    The low-mass protostellar region L1527 is unusual because it contains observable abundances of unsaturated carbon-chain molecules including CnH radicals, H2Cn carbenes, cyanopolyynes, and the negative ions C4H- and C6H-, all of which are more associated with cold cores than with protostellar regions. Sakai et al. suggested that these molecules are formed in L1527 from the chemical precursor methane, which evaporates from the grains during the heat-up of the region. With the gas-phase osu.03.2008 network extended to include negative ions of the families C-n, and CnH-, as well as the newly detected C3N-, we modeled the chemistry that occurs following methane evaporation at T ≈ 25-30 K. We are able to reproduce most of the observed molecular abundances in L1527 at a time of ≈5 × 103 yr. At later times, the overall abundance of anions become greater than that of electrons, which has an impact on many organic species and ions. The anion-to-neutral ratio in our calculation is in good agreement with observation for C6H-, but exceeds the observed ratio by more than 3 orders of magnitude for C4H-. In order to explain this difference, further investigation is needed on the rate coefficients for electron attachment and other reactions regarding anions.

  5. Anion exchange membrane

    DOEpatents

    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.

  6. From Ag{sub 2}Sb{sub 2}O{sub 6} to Cd{sub 2}Sb{sub 2}O{sub 7}: Investigations on an anion-deficient to ideal pyrochlore solid solution

    SciTech Connect

    Laurita, Geneva; Vielma, Jason; Winter, Florian; Berthelot, Romain; Largeteau, Alain; Pöttgen, Rainer; Schneider, G.; Subramanian, M.A.

    2014-02-15

    A complete solid solution between the anion-deficient pyrochlore Ag{sub 2}Sb{sub 2}O{sub 6} and the ideal pyrochlore Cd{sub 2}Sb{sub 2}O{sub 7} has been synthesized through the standard solid state ceramic method. Each composition has been characterized by various different techniques, including powder X-ray diffraction, optical spectroscopy, electron paramagnetic resonance and {sup 121}Sb Mössbauer spectroscopy. Computational methods based on density functional theory complement this investigation. Photocatalytic activity has been studied, and transport properties have been measured on pellets densified by spark plasma sintering. The analysis of the data collected from these various techniques enables a comprehensive characterization of the complete solid solution and revealed an anomalous behavior in the Cd-rich end of the solid solution, which has been proposed to arise from a possible radical O{sup −} species in small concentrations. - Graphical abstract: A complete solid solution between the anion-deficient pyrochlore Ag{sub 2}Sb{sub 2}O{sub 6} and the ideal pyrochlore Cd{sub 2}Sb{sub 2}O{sub 7} has been synthesized and investigated through various techniques including X-ray diffraction, electron paramagnetic spectroscopy, and {sup 121}Sb-Mössbauer spectroscopy. Optical and electrical measurements have been performed, and computational methods have been applied to determine the density of states. Photocatalytic activity was monitored by the degradation of Methylene Blue, and upon cadmium substitution, the degradation amount decreased, which is attributed primarily to the changing optical and electrical properties of the solid solution. Display Omitted - Highlights: • A complete solid solution between Ag{sub 2}Sb{sub 2}O{sub 6} and Cd{sub 2}Sb{sub 2}O{sub 7} has been synthesized. • XRD reveals a relatively constant lattice parameter as the series progresses. • Optical and electrical properties have been measured for the solid solution.

  7. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Alexander, S.; Hodgdon, R. B.

    1977-01-01

    The objective of NAS 3-20108 was the development and evaluation of improved anion selective membranes useful as efficient separators in a redox power storage cell system being constructed. The program was divided into three parts, (a) optimization of the selected candidate membrane systems, (b) investigation of alternative membrane/polymer systems, and (c) characterization of candidate membranes. The major synthesis effort was aimed at improving and optimizing as far as possible each candidate system with respect to three critical membrane properties essential for good redox cell performance. Substantial improvements were made in 5 candidate membrane systems. The critical synthesis variables of cross-link density, monomer ratio, and solvent composition were examined over a wide range. In addition, eight alternative polymer systems were investigated, two of which attained candidate status. Three other alternatives showed potential but required further research and development. Each candidate system was optimized for selectivity.

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

    PubMed

    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.

  9. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Hodgdon, R. B.; Waite, W. A.

    1982-01-01

    The synthesis and fabrication of polymeric anion permselective membranes for redox systems are discussed. Variations of the prime candidate anion membrane formulation to achieve better resistance and/or lower permeability were explored. Processing parameters were evaluated to lower cost and fabricate larger sizes. The processing techniques to produce more membranes per batch were successfully integrated with the fabrication of larger membranes. Membranes of about 107 cm x 51 cm were made in excellent yield. Several measurements were made on the larger sample membranes. Among the data developed were water transport and transference numbers for these prime candidate membranes at 20 C. Other work done on this system included characterization of a number of specimens of candidate membranes which had been returned after service lives of up to sixteen months. Work with new polymer constituents, with new N.P.'s, catalysts and backing fabrics is discussed. Some work was also done to evaluate other proportions of the ingredients of the prime candidate system. The adoption of a flow selectivity test at elevated temperature was explored.

  10. 25 CFR 900.196 - Do covered services include the conduct of clinical studies and investigations and the provision...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... studies and investigations and the provision of emergency services, including the operation of emergency motor vehicles? 900.196 Section 900.196 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR...-DETERMINATION AND EDUCATION ASSISTANCE ACT Federal Tort Claims Act Coverage General Provisions...

  11. 25 CFR 900.196 - Do covered services include the conduct of clinical studies and investigations and the provision...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... studies and investigations and the provision of emergency services, including the operation of emergency motor vehicles? 900.196 Section 900.196 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR...-DETERMINATION AND EDUCATION ASSISTANCE ACT Federal Tort Claims Act Coverage General Provisions...

  12. Clinical acid-base pathophysiology: disorders of plasma anion gap.

    PubMed

    Moe, Orson W; Fuster, Daniel

    2003-12-01

    The plasma anion gap is a frequently used parameter in the clinical diagnosis of a variety of conditions. The commonest application of the anion gap is to classify cases of metabolic acidosis into those that do and those that do not leave unmeasured anions in the plasma. While this algorithm is useful in streamlining the diagnostic process, it should not be used solely in this fashion. The anion gap measures the difference between the unmeasured anions and unmeasured cations and thus conveys much more information to the clinician than just quantifying anions of strong acids. In this chapter, the significance of the anion gap is emphasized and several examples are given to illustrate a more analytic approach to using the clinical anion gap; these include disorders of low anion gap, respiratory alkalosis and pyroglutamic acidosis.

  13. Alkali cation extraction by calix[4]crown-6 to room-temperature ionic liquids. The effect of solvent anion and humidity investigated by molecular dynamics simulations.

    PubMed

    Sieffert, N; Wipff, G

    2006-01-26

    We report a molecular dynamics study on the solvation of M+ (Na+ to Cs+) alkali cations and of their LM+ complexes with a calix[4]arene host (L = 1,3-dimethoxy-calix[4]arene-crown-6 in the 1,3-alternate conformation) in the [BMI][PF6] and [BMI][Tf2N] room-temperature ionic liquids "ILs" based on the BMI+ (1-butyl-3-methylimidazolium) cation. The comparison of the two liquids and the dry versus humid form of the former one (with a 1:1 ratio of H2O and BMI+PF6- species) reveals the importance of humidity: in [BMI][PF6]-dry as in the [BMI][Tf2N] liquid, the first solvation shell of the "naked" M+ ions is composed of solvent anions only (four PF6- anions, and from four to five Tf2N- anions, respectively, quasi-neutralized by a surrounding cage of BMI+ cations), while in the [BMI][PF6]-humid IL, it comprises from one to three solvent anions and about four H2O molecules. In the LM+ complexes, the cation is shielded from solvent, but still somewhat interacts with a solvent anion in the dry ILs and with water in the humid IL. We also report tests on M+ interactions with solvent anions PF6- and Tf2N- in the gas phase, showing that the AMBER results are in satisfactory agreement with QM results obtained at different levels of theory. The question of ion recognition by L is then examined by free energy perturbation studies in the three liquids, predicting a high Cs+/Na+ selectivity upon liquid extraction from an aqueous phase, in agreement with experimental results on a parent calixarene host. A similar Cs+/Na+ selectivity is predicted upon complexation in a homogeneous IL phase, mainly due to the desolvation energy of the free cations. Thus, despite their polar character, ionic liquids qualitatively behave as classical weakly polar organic liquids (e.g., choroform) as far as liquid-liquid extraction is concerned but more like polar liquids (water, alcohols) as far as complexation in a single phase is concerned.

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

    SciTech Connect

    Bowman-James, K.; Wilson, G.; Moyer, B. A.

    2004-12-11

    This project involves the design and synthesis of receptors for oxoanions of environmental importance, including emphasis on high level and low activity waste. Target anions have included primarily oxoanions and a study of the basic concepts behind selective binding of target anions. A primary target has been sulfate because of its deleterious influence on the vitrification of tank wastes

  15. Anion exchangers with negatively charged functionalities in hyperbranched ion-exchange layers for ion chromatography.

    PubMed

    Uzhel, Anna S; Zatirakha, Alexandra V; Smirnov, Konstantin N; Smolenkov, Alexandr D; Shpigun, Oleg A

    2017-01-27

    Novel pellicular poly(styrene-divinylbenzene)-based (PS-DVB) anion exchangers with covalently-bonded hyperbranched functional ion-exchange layers containing negatively charged functionalities are obtained and examined. The hyperbranched coating is created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE), and amination of the terminal epoxide rings with methylamine (MA) or glycine (Gly). The influence of the position and the number of the layers with glycine, as well as of the total number of the layers of amine in the coating on the chromatographic properties of the obtained stationary phases is investigated. Chromatographic performance of the obtained stationary phases is evaluated using the model mixtures of inorganic and organic anions with hydroxide eluent. It is shown that the best selectivity toward weakly retained organic acids and oxyhalides is possessed by the anion exchanger obtained after 5 modification cycles, with glycine being used in the first one. Such anion exchanger packed in 25-cm long column is capable of separating 22 anions in 58min including 7 standard anions, mono-, di- and trivalent organic acids, oxyhalides, and some other double- and triple-charged anions.

  16. Anion solvation in alcohols

    SciTech Connect

    Jonah, C.D.; Xujia, Zhang; Lin, Yi

    1996-03-01

    Anion solvation is measured in alcohols using pump-probe pulse radiolysis and the activation energy of solvation is determined. Solvation of an anion appears to be different than excited state solvation. The continuum dielectric model does not appear to explain the results.

  17. Polymers for anion recognition and sensing.

    PubMed

    Rostami, Ali; Taylor, Mark S

    2012-01-16

    In biological systems, the selective and high-affinity recognition of anionic species is accomplished by macromolecular hosts (anion-binding proteins) that have been "optimized" through evolution. Surprisingly, it is only recently that chemists have systematically attempted to develop anion-responsive synthetic macromolecules for potential applications in medicine, national security, or environmental monitoring. Recent results indicating that unique features of polymeric systems such as signal amplification, multivalency, and cooperative behavior may be exploited productively in the context of anion recognition and sensing are documented. The wide variety of interactions-including Lewis acid/base, ion-pairing, and hydrogen bonding-that have been employed for this purpose is reflected in the structural diversity of anion-responsive macromolecules identified to date.

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

    PubMed

    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.

  19. Fluorescence-lifetime-based sensors for anions

    NASA Astrophysics Data System (ADS)

    Teichmann, Maria; Draxler, Sonja; Kieslinger, Dietmar; Lippitsch, Max E.

    1997-05-01

    Sensing of anions has been investigated using the fluorescence decaytime as the information carrier. The sensing mechanism is based on the coextraction of an anion and a proton, and the presence of a fluorophore with a rather long fluorescence decaytime inside the membrane to act as a pH indicator. The relevant theory is discussed shortly. As an example a sensor for nitrate is shown, and the influence of ionic additives on the working function has been investigated.

  20. State-by-state investigation of destructive interference in resonance Raman spectra of neutral tyrosine and the tyrosinate anion with the simplified sum-over-states approach.

    PubMed

    Cabalo, Jerry B; Saikin, Semion K; Emmons, Erik D; Rappoport, Dmitrij; Aspuru-Guzik, Alán

    2014-10-16

    UV resonance Raman scattering is uniquely sensitive to the molecular electronic structure as well as intermolecular interactions. To better understand the relationship between electronic structure and resonance Raman cross section, we carried out combined experimental and theoretical studies of neutral tyrosine and the tyrosinate anion. We studied the Raman cross sections of four vibrational modes as a function of excitation wavelength, and we analyzed them in terms of the contributions of the individual electronic states as well as of the Albrecht A and B terms. Our model, which is based on time-dependent density functional theory (TDDFT), reproduced the experimental resonance Raman spectra and Raman excitation profiles for both studied molecules with good agreement. We found that for the studied modes, the contributions of Albrecht's B terms in the Raman cross sections were important across the frequency range spanning the L(a,b) and B(a,b) electronic excitations in tyrosine and the tyrosinate anion. Furthermore, we demonstrated that interference with high-energy states had a significant impact and could not be neglected even when in resonance with a lower-energy state. The symmetry of the vibrational modes served as an indicator of the dominance of the A or B mechanisms. Excitation profiles calculated with a damping constant estimated from line widths of the electronic absorption bands had the best consistency with experimental results.

  1. Anions coordinating anions: analysis of the interaction between anionic Keplerate nanocapsules and their anionic ligands.

    PubMed

    Melgar, Dolores; Bandeira, Nuno A G; Bonet Avalos, Josep; Bo, Carles

    2017-02-15

    Keplerates are a family of anionic metal oxide spherical capsules containing up to 132 metal atoms and some hundreds of oxygen atoms. These capsules holding a high negative charge of -12 coordinate both mono-anionic and di-anionic ligands thus increasing their charge up to -42, even up to -72, which is compensated by the corresponding counter-cations in the X-ray structures. We present an analysis of the relative importance of several energy terms of the coordinate bond between the capsule and ligands like carbonate, sulphate, sulphite, phosphinate, selenate, and a variety of carboxylates, of which the overriding component is contributed by solvation/de-solvation effects.

  2. Photoelectron spectroscopy of nitromethane anion clusters

    NASA Astrophysics Data System (ADS)

    Pruitt, Carrie Jo M.; Albury, Rachael M.; Goebbert, Daniel J.

    2016-08-01

    Nitromethane anion and nitromethane dimer, trimer, and hydrated cluster anions were studied by photoelectron spectroscopy. Vertical detachment energies, estimated electron affinities, and solvation energies were obtained from the photoelectron spectra. Cluster structures were investigated using theoretical calculations. Predicted detachment energies agreed with experiment. Calculations show water binds to nitromethane anion through two hydrogen bonds. The dimer has a non-linear structure with a single ionic Csbnd H⋯O hydrogen bond. The trimer has two different solvent interactions, but both involve the weak Csbnd H⋯O hydrogen bond.

  3. Capturing and concentrating adenovirus using magnetic anionic nanobeads

    PubMed Central

    Sakudo, Akikazu; Baba, Koichi; Ikuta, Kazuyoshi

    2016-01-01

    We recently demonstrated how various enveloped viruses can be efficiently concentrated using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). However, the exact mechanism of interaction between the virus particles and anionic beads remains unclear. To further investigate whether these magnetic anionic beads specifically bind to the viral envelope, we examined their potential interaction with a nonenveloped virus (adenovirus). The beads were incubated with either adenovirus-infected cell culture medium or nasal aspirates from adenovirus-infected individuals and then separated from the supernatant by applying a magnetic field. After thoroughly washing the beads, adsorption of adenovirus was confirmed by a variety of techniques, including immunochromatography, polymerase chain reaction, Western blotting, and cell culture infection assays. These detection methods positively identified the hexon and penton capsid proteins of adenovirus along with the viral genome on the magnetic beads. Furthermore, various types of adenovirus including Types 5, 6, 11, 19, and 41 were captured using the magnetic bead procedure. Our bead capture method was also found to increase the sensitivity of viral detection. Adenovirus below the detectable limit for immunochromatography was efficiently concentrated using the magnetic bead procedure, allowing the virus to be successfully detected using this methodology. Moreover, these findings clearly demonstrate that a viral envelope is not required for binding to the anionic magnetic beads. Taken together, our results show that this capture procedure increases the sensitivity of detection of adenovirus and would, therefore, be a valuable tool for analyzing both clinical and experimental samples. PMID:27274228

  4. Semi-analytical investigations of high area-to-mass ratio geosynchronous space debris including Earth’s shadowing effects

    NASA Astrophysics Data System (ADS)

    Valk, S.; Lemaître, A.

    2008-10-01

    This paper investigates the long-term perturbations of the orbits of geosynchronous space debris influenced by direct radiation pressure including the Earth's shadowing effects. For this purpose, we propose an extension of our homemade semi-analytical theory [Valk, S., Lemaître, A., Deleflie, F. Semi-analytical theory of mean orbital motion for geosynchronous space debris under gravitational influence. Adv. Space Res., submitted for publication], based on the method developed by Aksnes [Aksnes, K. Short-period and long-period perturbations of a spherical satellite due to direct solar radiation. Celest. Mech. Dyn. Astron. 13, 89-104, 1976] and generalized into a more convenient non-singular formalism. The perturbations accounting for the direct radiation pressure with the Earth's shadow are computed on a revolution-by-revolution basis, retaining the original osculating Hamiltonian disturbing function. In this framework, we compute the non-singular mean longitude at shadow entry and shadow exit at every orbital revolution in opposition to classical approaches where the singular eccentric anomalies at shadow entry and shadow exit are computed. This new algorithm is developed using non-singular variables. Consequently, it is particularly suitable for both near-circular and near-equatorial orbits as well as orbits which transit periodically around null eccentricities and null inclinations. The algorithm is tested by means of numerical integrations of the equations, averaged over the short periods, including radiation pressure, J2, the combined Moon and Sun third body attraction as well as the long-term effects of the 1:1 resonance occurring for geosynchronous objects. As an extension of [Valk, S., Lemaître, A., Anselmo, L. Analytical and semi-analytical investigations of geosynchronous space debris with high area-to-mass ratios influenced by solar radiation pressure. Adv. Space Res., doi:10.1016/j.asr.2007.10.025, 2007b], we especially apply our analysis to space

  5. Aza compounds as anion receptors

    DOEpatents

    Lee, Hung Sui; Yang, Xiao-Qing; McBreen, James

    1998-01-06

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of Li.sup.+ ion in alkali metal batteries.

  6. Aza compounds as anion receptors

    DOEpatents

    Lee, H.S.; Yang, X.Q.; McBreen, J.

    1998-01-06

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of Li{sup +} ion in alkali metal batteries. 3 figs.

  7. Cellulose Anionic Hydrogels Based on Cellulose Nanofibers As Natural Stimulants for Seed Germination and Seedling Growth.

    PubMed

    Zhang, Hao; Yang, Minmin; Luan, Qian; Tang, Hu; Huang, Fenghong; Xiang, Xia; Yang, Chen; Bao, Yuping

    2017-05-17

    Cellulose anionic hydrogels were successfully prepared by dissolving TEMPO-oxidized cellulose nanofibers in NaOH/urea aqueous solution and being cross-linked with epichlorohydrin. The hydrogels exhibited microporous structure and high hydrophilicity, which contribute to the excellent water absorption property. The growth indexes, including the germination rate, root length, shoot length, fresh weight, and dry weight of the seedlings, were investigated. The results showed that cellulose anionic hydrogels with suitable carboxylate contents as plant growth regulators could be beneficial for seed germination and growth. Moreover, they presented preferable antifungal activity during the breeding and growth of the sesame seed breeding. Thus, the cellulose anionic hydrogels with suitable carboxylate contents could be applied as soilless culture mediums for plant growth. This research provided a simple and effective method for the fabrication of cellulose anionic hydrogel and evaluated its application in agriculture.

  8. An alternative anionic bio-sustainable anti-fungal agent: Investigation of its mode of action on the fungal cell membrane.

    PubMed

    Stenbæk, Jonas; Löf, David; Falkman, Peter; Jensen, Bo; Cárdenas, Marité

    2017-07-01

    The potential of a lactylate (the sodium caproyl lactylate or C10 lactylate), a typical food grade emulsifier, as an anionic environmental friendly anti-fungal additive was tested in growth medium and formulated in a protective coating for exterior wood. Different laboratory growth tests on the blue stain fungus Aureobasidium pullulans were performed and its interactions on a model fungal cell membrane were studied. Promising short term anti-fungal effects in growth tests were observed, although significant but less dramatic effects took place in coating test on wood panels. Scanning electron microscope analysis shows clear differences in the amount of fungal slime on the mycelium of Aureobasidium pullulans when the fungus was exposed of C10 lactylate. This could indicate an effect on the pullulan and melanin production by the fungus. Moreover, the interaction studies on model fungal cell membranes show that C10 lactylate affects the phospholipid bilayer in a similar manner to other negative charged detergents.

  9. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-01

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm-1 and 4000-50 cm-1, respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion-1 and anion-2 conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1sbnd C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed.

  10. Static and time-resolved step-scan Fourier transform infrared investigations of the photoreaction of halorhodopsin from Natronobacterium pharaonis: consequences for models of the anion translocation mechanism.

    PubMed Central

    Hackmann, C; Guijarro, J; Chizhov, I; Engelhard, M; Rödig, C; Siebert, F

    2001-01-01

    The molecular changes during the photoreaction of halorhodopsin from Natronobacterium pharaonis have been monitored by low-temperature static and by time-resolved step-scan Fourier transform infrared difference spectroscopy. In the low-temperature L spectrum anions only influence a band around 1650 cm(-1), tentatively assigned to the C=N stretch of the protonated Schiff base of L. The analysis of the time-resolved spectra allows to identify the four states: K, L(1), L(2), and O. Between L(1) and L(2), only the apoprotein undergoes alterations. The O state is characterized by an all-trans chromophore and by rather large amide I spectral changes. Because in our analysis the intermediate containing O is in equilibrium with a state indistinguishable from L(2), we are unable to identify an N-like state. At very high chloride concentrations (>5 M), we observe a branching of the photocycle from L(2) directly back to the dark state, and we provide evidence for direct back-isomerization from L(2). This branching leads to the reported reduction of transport activity at such high chloride concentrations. We interpret the L(1) to L(2) transition as an accessibility change of the anion from the extracellular to the cytosolic side, and the large amide I bands in O as an indication for opening of the cytosolic channel from the Schiff base toward the cytosolic surface and/or as indication for changes of the binding constant of the release site. PMID:11423423

  11. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: a combined experimental and theoretical study.

    PubMed

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-25

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion(-1) and anion(-2) conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. (1)H and (13)C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed.

  12. R type anion channel

    PubMed Central

    Diatloff, Eugene; Peyronnet, Rémi; Colcombet, Jean; Thomine, Sébastien; Barbier-Brygoo, Hélène

    2010-01-01

    Plant genomes code for channels involved in the transport of cations, anions and uncharged molecules through membranes. Although the molecular identity of channels for cations and uncharged molecules has progressed rapidly in the recent years, the molecular identity of anion channels has lagged behind. Electrophysiological studies have identified S-type (slow) and R-type (rapid) anion channels. In this brief review, we summarize the proposed functions of the R-type anion channels which, like the S-type, were first characterized by electrophysiology over 20 years ago, but unlike the S-type, have still yet to be cloned. We show that the R-type channel can play multiple roles. PMID:21051946

  13. Several hemicyanine dyes as fluorescence chemosensors for cyanide anions

    NASA Astrophysics Data System (ADS)

    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.

  14. Anion-induced structural transformation of a sulfate-incorporated 2D Cd(II)-organic framework

    NASA Astrophysics Data System (ADS)

    Lee, Li-Wei; Luo, Tzuoo-Tsair; Wang, Chih-Min; Lee, Gene-Hsiang; Peng, Shie-Ming; Liu, Yen-Hsiang; Lee, Sheng-Long; Lu, Kuang-Lieh

    2016-07-01

    A Cd(II)-organic framework {[Cd2(tpim)4(SO4)(H2O)2]·(SO4)·21H2O}n (1) was synthesized by reacting CdSO4·8/3H2O and 2,4,5-tri(4-pyridyl)imidazole (tpim) under hydrothermal conditions. A structural analysis showed that compound 1 adopts a layered structure in which the [Cd(tpim)2]n chains are linked by sulfate anions. These 2D layers are further packed into a 3D supramolecular framework via π-π interactions. The structure contains two types of SO42- anions, i.e., bridging SO42- and free SO42- anions, the latter of which are included in the large channels of the framework. Compound 1 exhibits interesting anion exchange behavior. In the presence of SCN- anions, both the bridging and free SO42- anions in 1 were completely exchanged by SCN- ligands to form a 1D species [Cd(tpim)2(SCN)2] (1A), in which the SCN- moieties function as a monodentate ligand. On the other hand, when compound 1 was ion exchanged with N3- anions in aqueous solution, the bridging SO42- moieties remained intact, and only the free guest SO42- were replaced by N3- anions. The gas adsorption behavior of the activated compound 1 was also investigated.

  15. A review of the removal of anions and oxyanions of the halogen elements from aqueous solution by layered double hydroxides.

    PubMed

    Theiss, Frederick L; Couperthwaite, Sara J; Ayoko, Godwin A; Frost, Ray L

    2014-03-01

    The application of layered double hydroxides (LDHs) and thermally activated LDHs for the removal of various fluorine (F(-),BF4(-)), chlorine (Cl(-),ClO4(-)), bromine (Br(-),BrO3(-)) and iodine (I(-),IO3(-)) species from aqueous solutions has been reviewed in this article. LDHs and thermally activated LDHs were able to significantly reduce the concentration of selected anions in laboratory scale experiments. The M(2+):M(3+) cation ratio of the LDH adsorbent was an important factor which influenced anion uptake. Though LDHs were able to remove some target anion species through anion exchange and surface adsorption thermal activation and reformation generally produced better results. The presence of competing anions including carbonate, phosphate and sulphate had a significant impact on uptake of the target anion as LDHs typically exhibit lower affinity towards monovalent anions compared to anions with multiple charges. The removal of fluoride and perchlorate from aqueous solution by a continuous flow system utilising fixed bed columns packed with LDH adsorbents has also been investigated. The adsorption capacity of the columns at breakpoint was heavily dependent on the flow rate and lower than result reported for the corresponding batch methods. There is still considerable scope for future research on numerous topics summarised in this article. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Hosting anions. The energetic perspective.

    PubMed

    Schmidtchen, Franz P

    2010-10-01

    Hosting anions addresses the widely spread molecular recognition event of negatively charged species by dedicated organic compounds in condensed phases at equilibrium. The experimentally accessible energetic features comprise the entire system including the solvent, any buffers, background electrolytes or other components introduced for e.g. analysis. The deconvolution of all these interaction types and their dependence on subtle structural variation is required to arrive at a structure-energy correlation that may serve as a guide in receptor construction. The focus on direct host-guest interactions (lock-and-key complementarity) that have dominated the binding concepts of artificial receptors in the past must be widened in order to account for entropic contributions which constitute very significant fractions of the total free energy of interaction. Including entropy necessarily addresses the ambiguity and fuzziness of the host-guest structural ensemble and requires the appreciation of the fact that most liquid phases possess distinct structures of their own. Apparently, it is the perturbation of the intrinsic solvent structure occurring upon association that rules ion binding in polar media where ions are soluble and abundant. Rather than specifying peculiar structural elements useful in anion binding this critical review attempts an illumination of the concepts and individual energetic contributions resulting in the final observation of specific anion recognition (95 references).

  17. Cosmic X-ray Physics: Sounding rocket investigations of the diffuse X-ray background, including instrument development

    NASA Astrophysics Data System (ADS)

    McCammon, Dan

    We propose an investigation to improve our understanding of the Galactic diffuse X-ray background. The ultimate purpose of this is to determine the role of hot phases of the interstellar medium in mediating stellar feedback in star formation, in transport of metals, and in determining the structure and evolution of the Galaxy. It directly addresses SMD's astrophysics goal No. 2, to explore the origin and evolution of the galaxies, stars and planets that make up our universe. This work will involve a flight of an existing payload with small modifications in Woomera, South Australia, to observe the Galactic soft X-ray bulge and attempt to determine its nature and emission mechanisms. This flight should also either confirm or put strict upper limits on the "sterile neutrino" model for the 3.5 keV signal observed near the Galactic Center by XMM-Newton. Our investigation includes the development of thermal detectors with superconducting transition edge thermometers capable of 1-2 eV FWHM energy resolution in the 100-400 eV range with the intent of obtaining a scientifically useful spectrum on a sounding rocket flight of the emission from one million degree gas in this energy range. This will require a total area of 1-2 square centimeters for the detector array. To enable routine testing of such detectors in the lab and for necessary in-flight gain and resolution monitoring, we are trying to develop a pulsed-UV laser calibration source. In collaboration with Goddard Space Flight Center, we are investigating the practicality of waveguide-below-cutoff filters to provide the necessary attenuation of infrared radiation for these detectors while still allowing good x-ray transmission below 150 eV. The detectors, calibration source, filters, optimal high-rate pulse analysis and flight experience with the detector readouts are all relevant to future NASA major missions. The detectors we're working on for a low-energy sounding rocket flight would be an excellent match to what is

  18. Isatinphenylsemicarbazones as efficient colorimetric sensors for fluoride and acetate anions - anions induce tautomerism.

    PubMed

    Jakusová, Klaudia; Donovalová, Jana; Cigáň, Marek; Gáplovský, Martin; Garaj, Vladimír; Gáplovský, Anton

    2014-04-05

    The anion induced tautomerism of isatin-3-4-phenyl(semicarbazone) derivatives is studied herein. The interaction of F(-), AcO(-), H2PO4(-), Br(-) or HSO4(-) anions with E and Z isomers of isatin-3-4-phenyl(semicarbazone) and N-methylisatin-3-4-phenyl(semicarbazone) as sensors influences the tautomeric equilibrium of these sensors in the liquid phase. This tautomeric equilibrium is affected by (1) the inter- and intra-molecular interactions' modulation of isatinphenylsemicarbazone molecules due to the anion induced change in the solvation shell of receptor molecules and (2) the sensor-anion interaction with the urea hydrogens. The acid-base properties of anions and the difference in sensor structure influence the equilibrium ratio of the individual tautomeric forms. Here, the tautomeric equilibrium changes were indicated by "naked-eye" experiment, UV-VIS spectral and (1)H NMR titration, resulting in confirmation that appropriate selection of experimental conditions leads to a high degree of sensor selectivity for some investigated anions. Sensors' E and Z isomers differ in sensitivity, selectivity and sensing mechanism. Detection of F(-) or CH3COO(-) anions at high weakly basic anions' excess is possible.

  19. Investigation of gamma radiation effect on the anion exchange resin Amberlite IRA-400 in hydroxide form by Fourier transformed infrared and 13C nuclear magnetic resonance spectroscopies.

    PubMed

    Traboulsi, A; Dupuy, N; Rebufa, C; Sergent, M; Labed, V

    2012-03-02

    Radiation-induced decomposition of the anion exchange resin Amberlite IRA-400 in hydroxide form by gamma radiolysis has been studied under different irradiation doses and irradiation atmospheres. In this work, we focused on the degradation of the solid part of the resin by Fourier transformed infrared (FTIR) and (13)C nuclear magnetic resonance (NMR) spectroscopies associated with chemometric treatments. FTIR and (13)C NMR techniques showed that only -CH(2)N(+)(CH(3))(3) groups were detached from the resin whereas the polystyrene divinylbenzene backbone remains intact. The quaternary ammonium groups were replaced by amine or carbonyl groups according to the irradiation atmosphere (with or without water or oxygen). Principal components analysis (PCA) was used to classify the degraded resins according to their irradiation conditions by separating the effect of the dose or the environment. The PCA loadings have shown spectral regions which discriminate the irradiated resins whereas SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) allows to identify families of component characterizing the chemical structure of resins and estimate their relative contributions according to the irradiation atmospheres.

  20. Fractional factorial design to investigate the influence of heavy metals and anions on acid neutralization behavior of cement-based products.

    PubMed

    Polettini, A; Pomi, R; Sirini, P

    2002-04-01

    A major concern of cement-based solidification/stabilization of hazardous wastes is the interaction of waste contaminants on cement properties. Literature contains many examples of studies on the interference of individual contaminants on cement properties. Conversely, little information is available on how the interactions between contaminants affectthe properties of cement/waste systems. This paper provides a discussion on the interference mechanisms exerted by seven contaminants, five heavy metals and two anions, on cement hydration. The seven contaminants were selected on the basis of the typical composition of municipal solid waste incineration (MSWI) fly ash. Spiking experiments using pure compounds were performed according to a 2IV(7-3) fractional factorial design to simulate addition of MSWI fly ash to ordinary Portland cement. The acid neutralization behavior of the laboratory cement-contaminant mixtures was studied to detect the presence of solid phases responsible for the buffering capacity of the solid matrix. The results from the experimental work showed that Zn, Cl-, and SO4(2-) were the major factors influencing, occasionally in combination with other contaminants, strength and acid neutralization capacity of the cementitious products. The release of Cd, Cr, Cu, and Pb in the eluates as a function of pH also suggested possible chemical immobilization mechanisms of such metals within the hardened matrix.

  1. Anion-π catalysis.

    PubMed

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

    2014-02-05

    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

  2. Investigation of Changes in the Microscopic Structure of Anionic Poly(N-isopropylacrylamide-co-Acrylic acid) Microgels in the Presence of Cationic Organic Dyes toward Precisely Controlled Uptake/Release of Low-Molecular-Weight Chemical Compound.

    PubMed

    Kureha, Takuma; Shibamoto, Takahisa; Matsui, Shusuke; Sato, Takaaki; Suzuki, Daisuke

    2016-05-10

    Changes in a microscopic structure of an anionic poly(N-isopropylacrylamide-co-acrylic acid) microgel were investigated using small- and wide-angle X-ray scattering (SWAXS). The scattering profiles of the microgels were analyzed in a wide scattering vector (q) range of 0.07 ≤ q/nm(-1) ≤ 20. In particular, the microscopic structure of the microgel in the presence of a cationic dye rhodamine 6G (R6G) was characterized in terms of its correlation length (ξ), which represents the length scale of the spatial correlation of the network density fluctuations, and characteristic distance (d*), which originated from the local packing of isopropyl groups of two neighboring chains. In the presence of cationic R6G, ξ exhibited a divergent-like behavior, which was not seen in the absence of R6G, and d* was decreased with decreasing the volume of the microgel upon increasing temperature. At the same time, the amount of R6G adsorbed per unit mass of the microgel increased upon heating. These results suggested that a coil-to-globule transition of the poly(N-isopropylacrylamide) chains in the present anionic microgel occurred because of efficiently screened, thus, short ranged electrostatic repulsion between the charged groups, and hydrophobic interaction between the isopropyl groups in the presence of cationic R6G. The combination of hydrophobic and electrostatic interaction between the cationic dye and the microgel affected the separation and volume transition behavior of the microgel.

  3. Molecular dynamics investigation of the influence of anionic and zwitterionic interfaces on antimicrobial peptides’ structure: Implications for peptide toxicity and activity

    PubMed Central

    Khandelia, Himanshu; Kaznessis, Yiannis N.

    2008-01-01

    Molecular dynamics simulations of three related helical antimicrobial peptides have been carried out in zwitterionic diphosphocholine (DPC) micelles and anionic sodiumdodecylsulfate (SDS) micelles. These systems can be considered as model mammalian and bacterial membrane interfaces, respectively. The goal of this study is to dissect the differences in peptide composition which make the mutant peptides (novispirin-G10 and novispirin-T7) less toxic than the parent peptide ovispirin (OVIS), although all three peptides have highly antibacterial properties. Compared to G10 and T7, OVIS inserts deepest into the DPC micelle. This correlates well with the lesser toxicity of G10 and T7. There is strong evidence which suggests that synergistic binding of hydrophobic residues drives binding of OVIS to the micelle. The helical content of G10 and T7 is reduced in the presence of DPC, and this leads to less amphipathic peptide structures, which bind weakly to the micelle. Simulations in SDS were carried out to compare the influence of membrane electrostatics on peptide structure. All three peptides bound strongly to SDS, and retained helical form. This corresponds well with their equally potent antibacterial properties. Based on the simulations, we argue that secondary structure stability often leads to toxic properties. We also propose that G10 and T7 operate by the carpet mechanism of cell lysis. Toxicity of peptides operating by the carpet mechanism can be attenuated by reducing the peptide helical content. The simulations successfully capture experimental binding states, and the different depths of binding of the three peptides to the two micelles correlate with their antibacterial and toxic properties. PMID:16325306

  4. Cytotoxic mechanisms of hydrosulfide anion and cyanide anion in primary rat hepatocyte cultures.

    PubMed

    Thompson, Rodney W; Valentine, Holly L; Valentine, William M

    2003-06-30

    Hydrogen sulfide and hydrogen cyanide are known to compromise mitochondrial respiration through inhibition of cytochrome c oxidase and this is generally considered to be their primary mechanism of toxicity. Experimental studies and the efficiency of current treatment protocols suggest that H(2)S may exert adverse physiological effects through additional mechanisms. To evaluate the role of alternative mechanisms in H(2)S toxicity, the relative contributions of electron transport inhibition, uncoupling of mitochondrial respiration, and opening of the mitochondrial permeability transition pore (MPTP) to hydrosulfide and cyanide anion cytotoxicity in primary hepatocyte cultures were examined. Supplementation of hepatocytes with the glycolytic substrate, fructose, rescued hepatocytes from cyanide anion induced toxicity, whereas fructose supplementation increased hydrosulfide anion toxicity suggesting that hydrosulfide anion may compromise glycolysis in hepatocytes. Although inhibitors of the MPTP opening were protective for hydrosulfide anion, they had no effect on cyanide anion toxicity, consistent with an involvement of the permeability transition pore in hydrosulfide anion toxicity but not cyanide anion toxicity. Exposure of isolated rat liver mitochondria to hydrosulfide did not result in large amplitude swelling suggesting that if H(2)S induces the permeability transition it does so indirectly through a mechanism requiring other cellular components. Hydrosulfide anion did not appear to be an uncoupler of mitochondrial respiration in hepatocytes based upon the inability of oligomycin and fructose to protect hepatocytes from hydrosulfide anion toxicity. These findings support mechanisms additional to inhibition of cytochrome c oxidase in hydrogen sulfide toxicity. Further investigations are required to assess the role of the permeability transition in H(2)S toxicity, determine whether similar affects occur in other cell types or in vivo and evaluate whether this may

  5. Solvent-dependent enthalpic versus entropic anion binding by biaryl substituted quinoline based anion receptors.

    PubMed

    Sun, Zhan-Hu; Albrecht, Markus; Raabe, Gerhard; Pan, Fang-Fang; Räuber, Christoph

    2015-01-08

    Anion receptors based on an 8-thiourea substituted quinoline with pentafluorinated (1a) or nonfluorinated (1b) biarylamide groups in the 2-position show similar binding of halide anions with somewhat higher association constants for the more acidic fluorinated derivative. Surprisingly, binding affinities for the halides in the case of the nonfluorinated 1b are similar in nonpolar chloroform or polar DMSO as solvent. Thorough thermodynamic investigations based on NMR van't Hoff analysis show that anion binding in chloroform is mainly enthalpically driven. In DMSO, entropy is the driving force for the binding of the ions with replacement of attached solvent.

  6. Fabrication and investigation of MnFe2O4/MWCNTs nanocomposite by hydrothermal technique and adsorption of cationic and anionic dyes

    NASA Astrophysics Data System (ADS)

    Kafshgari, Leila Asadi; Ghorbani, Mohsen; Azizi, Asghar

    2017-10-01

    In present study, MnFe2O4/MWCNT nanocomposite synthesized using the hydrothermal technique and has been used for removal of DR16 and Y40 dyes from aqueous solutions. The characteristics results of FTIR, XRD, FESEM and TEM indicated that the nanoadsorbent was successfully fabricated. Magnetic sensitivity results demonstrated that the nanoparticles with saturation magnetization (Ms) value of 8.93 emu g-1 would have a fast magnetic response. The performance of adsorption was investigated in a batch reactor employing parameters expected to affect the maximum adsorption capacity (qm) such as pH, contact time, initial dye concentration and temperature. The highest sorption capacities of DR16 and Y40 after 300 min at 328 K were found to be 607.79 mg/g and 280 mg/g at pH of 2 and 6, respectively. The adsorption behavior over the time was assessed through pseudo-first, pseudo-second and Weber-Morris intra particle diffusion models. It was found that the pseudo-second order model gave the best agreement to the experimental data. Adsorbate-adsorbent interactions as a function of temperature was evaluated by Langmuir, Freundlich, Temkin and Sips isotherm models from which Sips isotherm had the highest consistency with the experimental data. Thermodynamic parameters including ΔG°, ΔS° and ΔH° were determined over the temperature range of 298-328 K. The results revealed that the adsorption reaction of DR16 onto MnFe2O4/MWCNT was spontaneous and exothermic, whilst the sorption process of Y40 was spontaneous and endothermic. In addition, activation energy values implied that the removal process of DR16 and Y40 was physical in nature.

  7. Purification Or Organic Acids Using Anion Exchange Chromatography.

    DOEpatents

    Ponnampalam; Elankovan

    2001-09-04

    Disclosed is a cost-effective method for purifying and acidifying carboxylic acids, including organic acids and amino acids. The method involves removing impurities by allowing the anionic form of the carboxylic acid to bind to an anion exchange column and washing the column. The carboxylic anion is displaced as carboxylic acid by washing the resin with a strong inorganic anion. This method is effective in removing organic carboxylic acids and amino acids from a variety of industrial sources, including fermentation broths, hydrolysates, and waste streams.

  8. Process for removing sulfate anions from waste water

    DOEpatents

    Nilsen, David N.; Galvan, Gloria J.; Hundley, Gary L.; Wright, John B.

    1997-01-01

    A liquid emulsion membrane process for removing sulfate anions from waste water is disclosed. The liquid emulsion membrane process includes the steps of: (a) providing a liquid emulsion formed from an aqueous strip solution and an organic phase that contains an extractant capable of removing sulfate anions from waste water; (b) dispersing the liquid emulsion in globule form into a quantity of waste water containing sulfate anions to allow the organic phase in each globule of the emulsion to extract and absorb sulfate anions from the waste water and (c) separating the emulsion including its organic phase and absorbed sulfate anions from the waste water to provide waste water containing substantially no sulfate anions.

  9. From anion receptors to transporters.

    PubMed

    Gale, Philip A

    2011-03-15

    Cystic fibrosis is the most well-known of a variety of diseases termed channelopathies, in which the regulation of ion transport across cell membranes is so disrupted that the threshold of a pathology is passed. The human toll exacted by these diseases has led a number of research groups, including our own, to create compounds that mediate ion transport across lipid bilayers. In this Account, we discuss three classes of synthetic compounds that were refined to bind and transport anions across lipid bilayer membranes. All of the compounds were originally designed as anion receptors, that is, species that would simply create stable complexes with anions, but were then further developed as transporters. By studying structurally simple systems and varying their properties to change the degree of preorganization, the affinity for anions, or the lipophilicity, we have begun to rationalize why particular anion transport mechanisms (cotransport or antiport processes) occur in particular cases. For example, we have studied the chloride transport properties of receptors based on the closely related structures of isophthalamide and pyridine-2,6-dicarboxamide: the central ring in each case was augmented with pendant methylimidazole groups designed to cotransport H(+) and Cl(-). We observed that the more preorganized pyridine-based receptor was the more efficient transporter, a finding replicated with a series of isophthalamides in which one contained hydroxyl groups designed to preorganize the receptor. This latter class of compound, together with the natural product prodigiosin, can transport bicarbonate (as part of a chloride/bicarbonate antiport process) across lipid bilayer membranes. We have also studied the membrane transport properties of calix[4]pyrroles. Although the parent meso-octamethylcalix[4]pyrrole functions solely as a Cs(+)/Cl(-) cotransporter, other compounds with increased anion affinities can function through an antiport process. One example is octafluoro

  10. FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS): Experimental Investigation of Quality of Lensless Ghost Imaging with Pseudo-Thermal Light

    NASA Astrophysics Data System (ADS)

    Shen, Xia; Bai, Yan-Feng; Qin, Tao; Han, Shen-Sheng

    2008-11-01

    Factors influencing the quality of lensless ghost imaging are investigated. According to the experimental results, we find that the imaging quality is determined by the number of independent sub light sources on the imaging plane of the reference arm. A qualitative picture based on advanced wave optics is presented to explain the physics behind the experimental phenomena. The present results will be helpful to provide a basis for improving the quality of ghost imaging systems in future works.

  11. Spectrophotometric investigation of the interactions between cationic (C.I. Basic Blue 9) and anionic (C.I. Acid Blue 25) dyes in adsorption onto extracted cellulose from Posidonia oceanic in single and binary system.

    PubMed

    Ben Douissa, Najoua; Dridi-Dhaouadi, Sonia; Mhenni, Mohamed Farouk

    2016-01-01

    Extracted cellulose from Posidonia oceanica was used as an adsorbent for removal of a cationic (Basic blue 9, BB) and anionic textile dye (Acid blue 25, AB) from aqueous solution in single dye system. Characterization of the extracted cellulose and extracted cellulose-dye systems were performed using several techniques such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential and Boehm acid-base titration method. Adsorption tests showed that the extracted cellulose presented higher adsorption of BB than AB in single dye system, revealing that electrostatic interactions are responsible, in the first instance, for the dye-adsorbent interaction. In single dye systems, the extracted cellulose presented the maximum adsorption capacities of BB and AB at 0.955 mmol.g(-1) and 0.370 mmol.g(-1), respectively. Adsorption experiments of AB dye on extracted cellulose saturated by BB dye exhibited the release of the latter dye from the sorbent which lead to dye-dye interaction in aqueous solution due to electrostatic attraction between both species. Interaction of BB and AB dyes were investigated using spectrophotometric analysis and results demonstrated the formation of a molecular complex detected at wavelengths 510 and 705 nm when anionic (AB) and cationic (BB) dye were taken in equimolar proportions. The adsorption isotherm of AB, taking into account the dye-dye interaction was investigated and showed that BB dye was released proportionately by AB equilibrium concentration. It was also observed that AB adsorption is widely enhanced when the formation of the molecular complex is disadvantaged.

  12. An anionic surfactant for EOR applications

    NASA Astrophysics Data System (ADS)

    Sagir, Muhammad; Tan, Isa M.; Mushtaq, Muhammad

    2014-10-01

    This work is to investigate the new anionic surfactants for the Enhanced Oil Recovery (EOR) application. Sulfonated anionic surfactant was produced by attaching SO3 to an ethoxylated alcohol to increase the performance of the surfactant. Methallyl chloride and ethoxylated alcohol was reacted followed by the reaction with sodium bisulfite to produce anionic sulfonated surfactant in 80.3 % yield. The sulfonation reaction parameters such as reactants mole ratio, reaction temperature and catalyst amount were optimized. The generation and stability of foam from the synthesized surfactant is also tested and results are reported. The synthesized novel surfactant was further investigated for the effect on the CO2 mobility in porous media and the findings are presented here. This in house developed surfactant has a great potential for CO2- EOR applications.

  13. Infrared spectroscopy of anionic hydrated fluorobenzenes

    NASA Astrophysics Data System (ADS)

    Schneider, Holger; Vogelhuber, Kristen M.; Weber, J. Mathias

    2007-09-01

    We investigate the structural motifs of anionic hydrated fluorobenzenes by infrared photodissociation spectroscopy and density functional theory. Our calculations show that all fluorobenzene anions under investigation are strongly distorted from the neutral planar molecular geometries. In the anions, different F atoms are no longer equivalent, providing structurally different binding sites for water molecules and giving rise to a multitude of low-lying isomers. The absorption bands for hexa- and pentafluorobenzene show that only one isomer for the respective monohydrate complexes is populated in our experiment. For C6F6-•H2O, we can assign these bands to an isomer where water forms a weak double ionic hydrogen bond with two F atoms in the ion, in accord with the results of Bowen et al. [J. Chem. Phys. 127, 014312 (2007), following paper.] The spectroscopic motif of the binary complexes changes slightly with decreasing fluorination of the aromatic anion. For dihydrated hexafluorobenzene anions, several isomers are populated in our experiments, some of which may be due to hydrogen bonding between water molecules.

  14. Anion-conducting polymer, composition, and membrane

    DOEpatents

    Pivovar, Bryan S [Los Alamos, NM; Thorn, David L [Los Alamos, NM

    2011-11-22

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  15. Anion-Conducting Polymer, Composition, and Membrane

    DOEpatents

    Pivovar, Bryan S.; Thorn, David L.

    2008-10-21

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  16. Anion-conducting polymer, composition, and membrane

    DOEpatents

    Pivovar, Bryan S.; Thorn, David L.

    2010-12-07

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  17. Anion-conducting polymer, composition, and membrane

    DOEpatents

    Pivovar, Bryan S.; Thorn, David L.

    2009-09-01

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  18. Sexual Health questions included in the Health Behaviour in School-aged Children (HBSC) Study: an international methodological pilot investigation.

    PubMed

    Young, Honor; Költő, András; Reis, Marta; Saewyc, Elizabeth M; Moreau, Nathalie; Burke, Lorraine; Cosma, Alina; Windlin, Béat; Gabhainn, Saoirse Nic; Godeau, Emmanuelle

    2016-12-05

    This paper describes the methodological developments of the sexual health items included in the Health Behaviour in School-aged Children (HBSC) study since their mandatory inclusion in the study in 2002. The current methodological, ethical and pedagogical challenges in measuring young people's sexual health behaviours are discussed along with the issues associated with the sexual health items introduced to the HBSC study in 2002. The development and piloting of new cross-national items for use in the 2013/14 HBSC data collection are presented and discussed. An international pilot study was undertaken to determine the impact of these proposed changes. Questionnaires and classroom discussion groups were conducted in five pilot countries in 2012/2013 (France, Hungary, Ireland, Portugal and Romania) with a total of 612 school-aged children (age M = 15.55 years, SD = 0.95). The majority of participants in each country provided positive feedback about the appropriateness of the questions. Some small cross-national differences were found in the self-reported quantitative data relating to the appropriateness of the questions (χ(2) = 22.831, df = 9, p = .007, V = .117). Qualitative feedback suggests that for the vast majority of students the phrasing and age-targeting of the questions were considered appropriate. With the exception of a small number of respondents who commented on the clarity and/or personal nature of the content, no specific issues with the questions were identified. These findings provide guidance on the answerability (including the extent of missing and inconsistent data), understandability, acceptability (including in different cultures) and relevance of questions to potential participants. The findings from the pilot study suggest that in general, the questions are understandable, acceptable, and of a high priority to the target population, and that the simplification has significantly reduced the proportion of missing data

  19. Fault Simulator with Dilatant Effects Used to Investigate Statistics of Foreshocks/Aftershocks, Including Magnitude Dependent Seismic Quiescence

    NASA Astrophysics Data System (ADS)

    Smith, D. E.; Sacks, S. I.; Rydelek, P. A.

    2011-12-01

    We add dilatant effects to a fault simulator to include physics consistent with observations of seismic quiescence. Using this simulator, we examine precursory and aftershock statistics of major events, changes in b-value, correlations between slip and static stress changes, changes in the in-plane focal mechanisms, and temporal decay of aftershocks. Seismic quiescence has been observed for a number major events including, 1982 Urakawa-Oki earthquake [Taylor et al., 1992], 1994 Hokkaido-Toho-Oki earthquake [Takanami et al., 1996], 1994 Northridge earthquake [Smith and Sacks, 2011], 1995 Kobe earthquake [Enescu et al., 2011], 1988 Spitak earthquake [Wysse and Martirosyan, 1998], and 2011 Tohoku earthquake [Katsumata, in press, 2011]. The physics of dilatancy theory [Nur, 1972; Whitcomb et al., 1973; Scholz et al., 1973], which we include in the simulator, is proposed as an explanation for seismic quiescence [Takanami et al., 1996; Scholz, 2000]. As the fault is loaded toward failure and the stress increases, if the stress is sufficiently high, the rock can begin to dilate. As dilation causes an increase in the rock volume, the pore pressure decreases, the effective normal stress increases, and the fault core strengthens [Rice, 1975]. Because the fault core supports more of the stress, the seismicity of the surrounding region will decrease as is observed. Over time (~2-20 years) the water will percolate back into the fault core from the surrounding region. The pore pressure in the fault core increases again, the normal stress decreases, and failure is encouraged. This dilatant effect on the fault core foreshocks, surrounding quiescence zone, and the aftershocks, can be studied by modifying the fault simulator of Sacks and Rydelek [1995]; Rydelek and Sacks [1996]. Based on simple physics: discrete patches, Coulomb failure, and redistribution of stresses on a specified fault geometry, this simulator (without dilatancy) has already been shown to reproduce Gutenberg

  20. Hydrogeochemical Investigations of Historic Mining Districts, Central Western Slope of Colorado, Including Influence on Surface-Water Quality

    USGS Publications Warehouse

    Nash, J. Thomas

    2002-01-01

    This report describes reconnaissance hydrogeochemical investigations of 22 mining districts on the Western Slope of Colorado in the Gunnison and Uncompahgre National Forests and adjacent public lands administered by the Bureau of Land Management. Sources and fates of contaminants from historic mines, mine waste, and mill tailings are interpreted from chemical analyses for 190 samples of surface waters; 185 samples of mined rocks, mill tailings, and altered rocks; and passive leach analyses of 116 samples of those mineralized materials. Short reaches of several headwater streams show relatively low level effects of historic mining; the headwaters of the Uncompahgre River are highly contaminated by mines and unmined altered rocks in the Red Mountain district. There is encouraging evidence that natural processes attenuate mine-related contamination in most districts.

  1. Zero-point energy effects in anion solvation shells.

    PubMed

    Habershon, Scott

    2014-05-21

    By comparing classical and quantum-mechanical (path-integral-based) molecular simulations of solvated halide anions X(-) [X = F, Cl, Br and I], we identify an ion-specific quantum contribution to anion-water hydrogen-bond dynamics; this effect has not been identified in previous simulation studies. For anions such as fluoride, which strongly bind water molecules in the first solvation shell, quantum simulations exhibit hydrogen-bond dynamics nearly 40% faster than the corresponding classical results, whereas those anions which form a weakly bound solvation shell, such as iodide, exhibit a quantum effect of around 10%. This observation can be rationalized by considering the different zero-point energy (ZPE) of the water vibrational modes in the first solvation shell; for strongly binding anions, the ZPE of bound water molecules is larger, giving rise to faster dynamics in quantum simulations. These results are consistent with experimental investigations of anion-bound water vibrational and reorientational motion.

  2. Hydrated hydride anion clusters

    NASA Astrophysics Data System (ADS)

    Lee, Han Myoung; Kim, Dongwook; Singh, N. Jiten; Kołaski, Maciej; Kim, Kwang S.

    2007-10-01

    On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion hydrated by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed.

  3. Anion permselective membrane

    NASA Astrophysics Data System (ADS)

    Hodgdon, R. B.; Waite, W. A.; Alexander, S. S.

    1984-07-01

    Two polymer ion exchange membranes were synthesized to fulfill the needs of both electrical resistivity and anolyte/catholyte separation for utility load leveling utilizing the DOE/NASA mixed electrolyte REDOX battery. Both membranes were shown to meet mixed electrolyte utility load leveling criteria. Several modifications of an anion exchange membrane failed to meet utility load leveling REDOX battery criteria using the unmixed electrolyte REDOX cell.

  4. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Hodgdon, R. B.; Waite, W. A.; Alexander, S. S.

    1984-01-01

    Two polymer ion exchange membranes were synthesized to fulfill the needs of both electrical resistivity and anolyte/catholyte separation for utility load leveling utilizing the DOE/NASA mixed electrolyte REDOX battery. Both membranes were shown to meet mixed electrolyte utility load leveling criteria. Several modifications of an anion exchange membrane failed to meet utility load leveling REDOX battery criteria using the unmixed electrolyte REDOX cell.

  5. Investigations on the Possibilities of Monitoring Coastal Changes Including Shallow Under Water Areas with Uas Photo Bathmetry

    NASA Astrophysics Data System (ADS)

    Grenzdörffer, G. J.; Naumann, M.

    2016-06-01

    UAS become a very valuable tool for coastal morphology. Not only for mapping but also for change detection and a better understanding of processes along and across the shore. This contribution investigates the possibilities of UAS to determine the water depth in clear shallow waters by means of the so called "photo bathymetry". From the results of several test flights it became clear that three factors influence the ability and the accuracy of bathymetric sea floor measurements. Firstly, weather conditions. Sunny weather is not always good. Due to the high image resolution the sunlight gets focussed even in very small waves causing moving patterns on shallow grounds with high reflection properties, such as sand. This effect invisible under overcast weather conditions. Waves, may also introduce problems and mismatches. Secondly the quality and the accuracy of the georeferencing with SFM algorithms. As multi image key point matching will not work over water, the proposed approach will only work for projects closely to the coastline with enough control on the land. Thirdly the software used and the intensity of post processing and filtering. Refraction correction and the final interpolation of the point cloud into a DTM are the last steps. If everything is done appropriately, accuracies in the bathymetry in the range of 10 - 50 cm, depending on the water depth are possible.

  6. A new type of anionic surfactant with four carboxylates for the preparation of mesoporous materials

    NASA Astrophysics Data System (ADS)

    Sun, Lin-Hao; Wang, Song; Shi, Wei-Lin; Zhang, Shuming; Chen, Xi; Cai, Qiang

    2012-09-01

    In this paper, a new type of anionic surfactant containing four carboxylates was synthesized by a four-step synthetic reaction including bromination reaction and primary amide protective reaction. Intermediates and final products of each step in the whole synthetic process were characterized by 1H NMR and MS. Purification of the anionic surfactant was accomplished through combination of recrystallization and silica gel column chromatography. The structure and the critical micelle concentration (CMC) of this surfactant at different temperatures were also investigated. Unlike traditional monocarboxylate surfactant easy to form lamellar mesostructure, this surfactant has the hexagonal mesophase structure and comparatively low CMC, hopefully to be applied in the preparation of mesoporous metal oxides.

  7. Bipyrrole-Strapped Calix[4]pyrroles: Strong Anion Receptors That Extract the Sulfate Anion

    SciTech Connect

    Kim, Sung Kuk; Lee, Juhoon; Williams, Neil J; Lynch, Vincent M.; Hay, Benjamin; Moyer, Bruce A; Sessler, Jonathan L.

    2014-01-01

    Cage-type calix[4]pyrroles 2 and 3 bearing two additional pyrrole groups on the strap have been synthesized. Compared with the parent calix[4]pyrrole (1), they were found to exhibit remarkably enhanced affinities for anions, including the sulfate anion (TBA+ salts), in organic media (CD2Cl2). This increase is ascribed to participation of the bipyrrole units in anion binding. Receptors 2 and 3 extract the hydrophilic sulfate anion (as the methyltrialkyl(C8-10)ammonium (A336+) salt)) from aqueous media into a chloroform phase with significantly improved efficiency (>10-fold relative to calix[4]pyrrole 1). These two receptors also solubilize into chloroform the otherwise insoluble sulfate salt, (TMA)2SO4 (tetramethylammonium sulfate).

  8. Study of the selectivity of inorganic anions in hydro-organic solvents using indirect capillary electrophoresis.

    PubMed

    Diress, Abebaw G; Lucy, Charles A

    2005-08-26

    In capillary electrophoresis (CE) analysis of small inorganic anions, the ability to control the electroosmotic flow (EOF) and the ability to alter the electrophoretic mobility of the ions are essential to improve resolution and separation speed. In this work, a CE method for separation of small inorganic anions using indirect detection in mixed methanol/water buffers is presented. The suitability of different UV absorbing probes commonly used for indirect detection including chromate, iodide, phthalate, benzoate, trimellitate, and pyromellitate, in mixed methanol/water buffers is examined. The effect of the electrolyte buffer system, including the pH, buffer concentration and the organic solvent on the electrophoretic mobility of the probes and analytes are also investigated. The EOF was reversed using cationic surfactant, cetyltrimethylammonium bromide (CTAB) so ions were separated under co-EOF mode. The organic solvent alters the electrophoretic mobility of the probes and the analytes differently and hence choice of the appropriate probe is essential to achieve high degree of detection sensitivity. Separations of six anions in less than 2.5 min were accomplished in buffers containing up to 30% MeOH. Adjustment of the methanol content helps to improve the selectivity and resolution of inorganic anions. Limit of detection, reproducibility and application of the method for quantification of anions in water samples will also be discussed.

  9. Investigation on the neutral and anionic BxAlyH2 (x + y = 7, 8, 9) clusters using density functional theory combined with photoelectron spectroscopy.

    PubMed

    Ding, Li-Ping; Shao, Peng; Lu, Cheng; Zhang, Fang-Hui; Ding, Lei; Yuan, Tao Li

    2016-08-17

    The structure and bonding nature of neutral and negatively charged BxAlyH2 (x + y = 7, 8, 9) clusters are investigated with the aid of previously published experimental photoelectron spectra combined with the present density functional theory calculations. The comparison between the experimental photoelectron spectra and theoretical simulated spectra helps to identify the ground state structures. The accuracy of the obtained ground state structures is further verified by calculating their adiabatic electron affinities and vertical detachment energies and comparing them against available experimental data. The results show that the structures of BxAlyH2 transform from three-dimensional to planar structures as the number of boron atoms increases. Moreover, boron atoms tend to bind together forming Bn units. The hydrogen atoms prefer to bind with boron atoms rather than aluminum atoms. The analyses of the molecular orbital on the ground state structures further support the abovementioned results.

  10. Probing the Structures and Electronic Properties of Dual-Phosphorus-Doped Gold Cluster Anions (AunP-2, n = 1–8): A Density functional Theory Investigation

    SciTech Connect

    Xu, Kang-Ming; Huang, Teng; Liu, Yi-Rong; Jiang, Shuai; Zhang, Yang; Lv, Yu-Zhou; Gai, Yan-Bo; Huang, Wei

    2015-07-29

    The geometries of gold clusters doped with two phosphorus atoms, (AunP-2, n = 1–8) were investigated using density functional theory (DFT) methods. Various two-dimensional (2D) and three-dimensional (3D) structures of the doped clusters were studied. The results indicate that the structures of dual-phosphorus-doped gold clusters exhibit large differences from those of pure gold clusters with small cluster sizes. In our study, as for Au6P-2, two cis–trans isomers were found. The global minimum of Au8P-2 presents a similar configuration to that of Au-20, a pyramid-shaped unit, and the potential novel optical and catalytic properties of this structure warrant further attention. The higher stability of AunP-2 clusters relative to Au-n+2 (n = 1–8) clusters was verified based on various energy parameters, and the results indicate that the phosphorus atom can improve the stabilities of the gold clusters. We then explored the evolutionary path of (n = 1–8) clusters. We found that AunP-2 clusters exhibit the 2D–3D structural transition at n = 6, which is much clearer and faster than that of pure gold clusters and single-phosphorus-doped clusters. The electronic properties of AunP-2 (n = 1–8) were then investigated. The photoelectron spectra provide additional fundamental information on the structures and molecular orbitals shed light on the evolution of AunP-2 (n = 1–8). Natural bond orbital (NBO) described the charge distribution in stabilizing structures and revealed the strong relativistic effects of the gold atoms.

  11. Optical dipole-force cooling of anions in a Penning trap

    NASA Astrophysics Data System (ADS)

    Fesel, Julian; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2017-09-01

    We discuss the possibility of using optical dipole forces for Sisyphus cooling of ions stored in a Penning trap by addressing the specific case of the molecular cooling candidate C2 -. Using a GPU accelerated code for Penning trap simulations, which we extended to include the molecule-light interaction, we show that this scheme can decrease the time required for cooling by an order of magnitude with respect to Doppler cooling. In our simulation we found that a reduction of the axial anion temperature from 10 K to 50 mK in around 10 s is possible. The temperature of the radial degrees of freedom was seen to thermalize to 150 mK . Based on the laser-cooled C2 -, a study on the sympathetic cooling of anions with masses 1-50 nucleon was performed, covering relevant candidates for investigations of chemical anion reactions at ultracold temperatures as well as for antimatter studies.

  12. Removal of Congo Red from Aqueous Solution by Anion Exchange Membrane (EBTAC): Adsorption Kinetics and Themodynamics.

    PubMed

    Khan, Muhammad Imran; Akhtar, Shahbaz; Zafar, Shagufta; Shaheen, Aqeela; Khan, Muhammad Ali; Luque, Rafael; Rehman, Aziz Ur

    2015-07-08

    The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were calculated for the adsorption of congo red, indicating an exothermic process.

  13. The Synthesis and Anion Recognition Property of Symmetrical Chemosensors Involving Thiourea Groups: Theory and Experiments.

    PubMed

    Shang, Xuefang; Yang, Zhenhua; Fu, Jiajia; Zhao, Peipei; Xu, Xiufang

    2015-11-06

    The synthesis of four symmetrical compounds containing urea/thiourea and anthracene/nitrobenzene groups was optimized. N,N'-Di((anthracen-9-yl)-methylene) thio-carbonohydrazide showed sensitive and selective binding ability for acetate ion among the studied anions. The presence of other competitive anions including F(-), H₂PO₄(-), Cl(-), Br(-) and I(-) did not interfere with the strong binding ability. The mechanism of the host-guest interaction was through multiple hydrogen bonds due to the conformational complementarity and higher basicity. A theoretical investigation explained that intra-molecular hydrogen bonds existed in the compound which could strengthen the anion binding ability. In addition, molecular frontier orbitals in molecular interplay were introduced in order to explain the red-shift phenomenon in the host-guest interaction process. Compounds based on thiourea and anthracene derivatives can thus be used as a chemosensor for detecting acetate ion in environmental and pharmaceutical samples.

  14. The Synthesis and Anion Recognition Property of Symmetrical Chemosensors Involving Thiourea Groups: Theory and Experiments

    PubMed Central

    Shang, Xuefang; Yang, Zhenhua; Fu, Jiajia; Zhao, Peipei; Xu, Xiufang

    2015-01-01

    The synthesis of four symmetrical compounds containing urea/thiourea and anthracene/nitrobenzene groups was optimized. N,N’-Di((anthracen-9-yl)-methylene)thio-carbonohydrazide showed sensitive and selective binding ability for acetate ion among the studied anions. The presence of other competitive anions including F−, H2PO4−, Cl−, Br− and I− did not interfere with the strong binding ability. The mechanism of the host-guest interaction was through multiple hydrogen bonds due to the conformational complementarity and higher basicity. A theoretical investigation explained that intra-molecular hydrogen bonds existed in the compound which could strengthen the anion binding ability. In addition, molecular frontier orbitals in molecular interplay were introduced in order to explain the red-shift phenomenon in the host-guest interaction process. Compounds based on thiourea and anthracene derivatives can thus be used as a chemosensor for detecting acetate ion in environmental and pharmaceutical samples. PMID:26561816

  15. Anion permselective membrane

    NASA Technical Reports Server (NTRS)

    Hodgdon, R. B.; Waite, W. A.

    1980-01-01

    The efforts on the synthesis of polymer anion redox membranes were mainly concentrated in two areas, membrane development and membrane fabrication. Membrane development covered the preparation and evaluation of experimental membranes systems with improved resistance stability and/or lower permeability. Membrane fabrication covered the laboratory scale production of prime candidate membranes in quantities of up to two hundred and sizes up to 18 inches x 18 inches (46 cm x 46 cm). These small (10 in x 11 in) and medium sized membranes were mainly for assembly into multicell units. Improvements in processing procedures and techniques for preparing such membrane sets lifted yields to over 90 percent.

  16. Removal of chloride ion from aqueous solution by ZnAl-NO(3) layered double hydroxides as anion-exchanger.

    PubMed

    Lv, Liang; Sun, Peide; Gu, Zhengyu; Du, Hangeng; Pang, Xiangjun; Tao, Xiaohong; Xu, Rufeng; Xu, Lili

    2009-01-30

    The layered double hydroxides (LDHs) containing nitrate as the interlayer anion has a high anion-exchange capacity in the presence of appropriate anions. In the light of this, ZnAl-NO(3) LDHs have been employed to remove chloride ion from aqueous solution in a batch mode. The influences of conditions for chloride ion uptake, including dosage of LDHs, pH of aqueous solution, and temperature on anion-exchange have been investigated, respectively. The thermodynamic parameters including Gibbs free energy (DeltaG(0)), standard enthalpy change (DeltaH(0)), and standard entropy change (DeltaS(0)) for the process were calculated using the Langmuir constants. It was found from kinetics test that the pseudo-second order kinetics model could be used to well describe the uptake process. An E(a) value of 10.27 kJ/mol provides evidence the anion-exchange process. The explanation of anion-exchange phenomenon has also been supported by X-ray diffraction and FT-IR spectra.

  17. Anion-Channel Blockers Inhibit S-Type Anion Channels and Abscisic Acid Responses in Guard Cells.

    PubMed Central

    Schwartz, A.; Ilan, N.; Schwarz, M.; Scheaffer, J.; Assmann, S. M.; Schroeder, J. I.

    1995-01-01

    The effects of anion-channel blockers on light-mediated stomatal opening, on the potassium dependence of stomatal opening, on stomatal responses to abscisic acid (ABA), and on current through slow anion channels in the plasma membrane of guard cells were investigated. The anion-channel blockers anthracene-9-carboxylic acid (9-AC) and niflumic acid blocked current through slow anion channels of Vicia faba L. guard cells. Both 9-AC and niflumic acid reversed ABA inhibition of stomatal opening in V. faba L. and Commelina communis L. The anion-channel blocker probenecid also abolished ABA inhibition of stomatal opening in both species. Additional tests of 9-AC effects on stomatal aperture in Commelina revealed that application of this anion-channel blocker allowed wide stomatal opening under low (1 mM) KCI conditions and increased the rate of stomatal opening under both low and high (100 mM) KCI conditions. These results indicate that anion channels can function as a negative regulator of stomatal opening, presumably by allowing anion efflux and depolarization, which prohibits ion up-take in guard cells. Furthermore, 9-AC prevented ABA induction of stomatal closure. A model in which ABA activation of anion channels contributes a rate-limiting mechanism during ABA-induced stomatal closure and inhibition of stomatal opening is discussed. PMID:12228619

  18. Anion-Channel Blockers Inhibit S-Type Anion Channels and Abscisic Acid Responses in Guard Cells.

    PubMed

    Schwartz, A.; Ilan, N.; Schwarz, M.; Scheaffer, J.; Assmann, S. M.; Schroeder, J. I.

    1995-10-01

    The effects of anion-channel blockers on light-mediated stomatal opening, on the potassium dependence of stomatal opening, on stomatal responses to abscisic acid (ABA), and on current through slow anion channels in the plasma membrane of guard cells were investigated. The anion-channel blockers anthracene-9-carboxylic acid (9-AC) and niflumic acid blocked current through slow anion channels of Vicia faba L. guard cells. Both 9-AC and niflumic acid reversed ABA inhibition of stomatal opening in V. faba L. and Commelina communis L. The anion-channel blocker probenecid also abolished ABA inhibition of stomatal opening in both species. Additional tests of 9-AC effects on stomatal aperture in Commelina revealed that application of this anion-channel blocker allowed wide stomatal opening under low (1 mM) KCI conditions and increased the rate of stomatal opening under both low and high (100 mM) KCI conditions. These results indicate that anion channels can function as a negative regulator of stomatal opening, presumably by allowing anion efflux and depolarization, which prohibits ion up-take in guard cells. Furthermore, 9-AC prevented ABA induction of stomatal closure. A model in which ABA activation of anion channels contributes a rate-limiting mechanism during ABA-induced stomatal closure and inhibition of stomatal opening is discussed.

  19. Molecular dynamics investigations of regioselectivity of anionic/aromatic substrates by a family of enzymes: a case study of diclofenac binding in CYP2C isoforms.

    PubMed

    Cui, Ying-Lu; Xu, Fang; Wu, Rongling

    2016-06-29

    The CYP2C subfamily is of particular importance in the metabolism of drugs, food toxins, and procarcinogens. Like other P450 subfamilies, 2C enzymes share a high sequence identity, but significantly contribute in different ways to hepatic capacity to metabolize drugs. They often metabolize the same substrate to more than one product with different catalytic sites. Because it is challenging to characterize experimentally, much still remains unknown about the reason for why the substrate regioselectivity of these closely related subfamily members is different. Here, we have investigated the structural features of CYP2C8, CYP2C9, and CYP2C19 bound with their shared substrate diclofenac to elucidate the underlying molecular mechanism for the substrate regioselectivity of CYP2C subfamily enzymes. The obtained results demonstrate how a sequence divergence for the active site residues causes heterogeneous variations in the secondary structures and in major tunnel selections, and further affects the shape and chemical properties of the substrate-binding site. Structural analysis and free energy calculations showed that the most important determinants of regioselectivity among the CYP2C isoforms are the geometrical features of the active sites, as well as the hydrogen bonds and the hydrophobic interactions, mainly presenting as the various locations of Arg108 and substitutions of Phe205 for Ile205 in CYP2C8. The MM-GB/SA calculations combined with PMF results accord well with the experimental KM values, bridging the gap between the theory and the experimentally observed results of binding affinity differences. The present study provides important insights into the structure-function relationships of CYP2C subfamily enzymes, the knowledge of ligand binding characteristics and key residue contributions could guide future experimental and computational work on the synthesis of drugs with better pharmacokinetic properties so that CYP interactions could be avoided.

  20. Reactions between microhydrated superoxide anions and formic acid.

    PubMed

    Ryding, Mauritz Johan; Fernández, Israel; Uggerud, Einar

    2017-08-30

    Reactions between water clusters containing the superoxide anion, O2˙(-)(H2O)n (n = 0-4), and formic acid, HCO2H, were studied experimentally in vacuo and modelled using quantum chemical methods. Encounters between microhydrated superoxide and formic acid were found to result in a number of different reactions, including (a) proton transfer, (b) ligand exchange, (c) H2-elimination (affording microhydrated CO4˙(-)), and (d) dihydrogen transfer (affording H2O2 and microhydrated CO2˙(-)). The effect of reactant-ion hydration on reaction rates was investigated and the involved reaction mechanisms were elucidated.

  1. Old acid, new chemistry. Negative metal anions generated from alkali metal oxalates and others.

    PubMed

    Curtis, Sharon; Renaud, Justin; Holmes, John L; Mayer, Paul M

    2010-11-01

    A brief search in Sci Finder for oxalic acid and oxalates will reward the researcher with a staggering 129,280 hits. However, the generation of alkali metal and silver anions via collision-induced dissociation of the metal oxalate anion has not been previously been reported, though Tian and coworkers recently investigated the dissociation of lithium oxalate. The exothermic decomposition of alkali metal oxalate anion to carbon dioxide in the collision cell of a triple quadrupole mass spectrometer leaves no place for the electron to reside, resulting in a double electron-transfer reaction to produce an alkali metal anion. This reaction is facilitated by the negative electron affinity of carbon dioxide and, as such, the authors believe that metal oxalates are potentially unique in this respect. The observed dissociation reactions for collision with argon gas (1.7-1.8 × 10(-3) mbar) for oxalic acid and various alkali metal oxalates are discussed and summarized. Silver oxalate is also included to demonstrate the propensity of this system to generate transition-metal anions, as well.

  2. Multivariate analysis of the association of bromocresol purple anion with bovine serum albumin.

    PubMed

    Nakamaru, Y; Sato, C

    1997-09-05

    The interaction of bromocresol purple (BCP) anions with bovine serum albumin (BSA) was investigated by principal factor analysis method, and reaction model, the number of molecular species and spectra of each component present in the reaction mixture were determined. The number of molecular species concerning the absorption intensity was three, including free BCP anion. Most part of the spectral change could be explained by the monomer binding of bromocresol purple anion (D) to serum albumin (P), a simple one step equilibrium, P + D = PD. A second type of association of BCP anions with serum albumin was also present, though in a small amount. Of six models tested which consisted of three or four molecular species, the sequential two step reaction model, P = PD = PD2, was the best model to explain the spectral data, and an existence of BCP anions as a dimer on the serum albumin was demonstrated. The dissociation constants were estimated at K1 = 1.6 x 10(-6) M for the first step and K2 = 1.2 x 10(-5) M for the second step.

  3. Pseudorotation in fullerene anions

    NASA Astrophysics Data System (ADS)

    Dunn, Janette L.; Hands, Ian D.; Bates, Colin A.

    2007-07-01

    Jahn-Teller (JT) problems are often characterised by an adiabatic potential energy surface (APES) containing either a set of isoenergetic wells or a trough of equivalent-energy points, which may be warped by higher-order coupling terms or anisotropic effects. In all three cases, the JT effect will be dynamic. Either tunnelling between the wells or rotation (of a distortion) around the trough will restore the original symmetry of the system. This motion is referred to as pseudorotation. It should be possible to observe a JT system in a distorted geometry if measurements are made on a sufficiently short timescale. In various cubic systems, this timescale has been calculated to be the order of picoseconds. Such timescales are accessible using modern methods of ultrafast spectroscopy. Measurements of pseudorotation rates can lead to important information on the strength and nature of the JT coupling present. We will present analytical calculations that allow the rate of pseudorotation to be determined in terms of the vibronic coupling parameters. We will show how these results can be applied to E ⊗ e systems and then to the more complicated system applicable to C60- anions. This is of particular interest because of the high icosahedral symmetry of fullerene ions and also because of the many potential uses of materials containing these ions. We conclude by outlining experiments that should be capable of measuring pseudorotation in C 60 anions.

  4. Anion-induced structural transformation of a sulfate-incorporated 2D Cd(II)–organic framework

    SciTech Connect

    Lee, Li-Wei; Luo, Tzuoo-Tsair; Wang, Chih-Min; Lee, Gene-Hsiang; Peng, Shie-Ming; Liu, Yen-Hsiang; Lee, Sheng-Long; Lu, Kuang-Lieh

    2016-07-15

    A Cd(II)–organic framework {[Cd_2(tpim)_4(SO_4)(H_2O)_2]·(SO_4)·21H_2O}{sub n} (1) was synthesized by reacting CdSO{sub 4}·8/3H{sub 2}O and 2,4,5-tri(4-pyridyl)imidazole (tpim) under hydrothermal conditions. A structural analysis showed that compound 1 adopts a layered structure in which the [Cd(tpim){sub 2}]{sub n} chains are linked by sulfate anions. These 2D layers are further packed into a 3D supramolecular framework via π–π interactions. The structure contains two types of SO{sub 4}{sup 2−} anions, i.e., bridging SO{sub 4}{sup 2−} and free SO{sub 4}{sup 2−} anions, the latter of which are included in the large channels of the framework. Compound 1 exhibits interesting anion exchange behavior. In the presence of SCN{sup −} anions, both the bridging and free SO{sub 4}{sup 2−} anions in 1 were completely exchanged by SCN{sup −} ligands to form a 1D species [Cd(tpim){sub 2}(SCN){sub 2}] (1A), in which the SCN{sup –} moieties function as a monodentate ligand. On the other hand, when compound 1 was ion exchanged with N{sub 3}{sup −} anions in aqueous solution, the bridging SO{sub 4}{sup 2−} moieties remained intact, and only the free guest SO{sub 4}{sup 2−} were replaced by N{sub 3}{sup −} anions. The gas adsorption behavior of the activated compound 1 was also investigated. - Highlights: • An interesting anion-induced structural transformation of a sulfate-incorporated 2D Cd(II)–organic framework is reported. • The sulfate-incorporated 2D layer compound exhibits very different anion exchange behavior with respect to SCN{sup −} and N{sub 3}{sup −}. • Both the bridging and free SO{sub 4}{sup 2−} anions in the 2D structure were completely exchanged by SCN{sup −} ligands, resulting in the formation of a 1D species. However, in the case of N{sub 3}{sup −} anions, only the free guest SO{sub 4}{sup 2−} in the structure was replaced.

  5. Dynamic chemistry of anion recognition

    SciTech Connect

    Custelcean, Radu

    2012-01-01

    In the past 40 years, anion recognition by synthetic receptors has grown into a rich and vibrant research topic, developing into a distinct branch of Supramolecular Chemistry. Traditional anion receptors comprise organic scaffolds functionalized with complementary binding groups that are assembled by multistep organic synthesis. Recently, a new approach to anion receptors has emerged, in which the host is dynamically self-assembled in the presence of the anionic guest, via reversible bond formation between functional building units. While coordination bonds were initially employed for the self-assembly of the anion hosts, more recent studies demonstrated that reversible covalent bonds can serve the same purpose. In both cases, due to their labile connections, the molecular constituents have the ability to assemble, dissociate, and recombine continuously, thereby creating a dynamic combinatorial library (DCL) of receptors. The anionic guests, through specific molecular recognition, may then amplify (express) the formation of a particular structure among all possible combinations (real or virtual) by shifting the equilibria involved towards the most optimal receptor. This approach is not limited to solution self-assembly, but is equally applicable to crystallization, where the fittest anion-binding crystal may be selected. Finally, the pros and cons of employing dynamic combinatorial chemistry (DCC) vs molecular design for developing anion receptors, and the implications of both approaches to selective anion separations, will be discussed.

  6. Vibrational spectroscopy of microhydrated conjugate base anions.

    PubMed

    Asmis, Knut R; Neumark, Daniel M

    2012-01-17

    Conjugate-base anions are ubiquitous in aqueous solution. Understanding the hydration of these anions at the molecular level represents a long-standing goal in chemistry. A molecular-level perspective on ion hydration is also important for understanding the surface speciation and reactivity of aerosols, which are a central component of atmospheric and oceanic chemical cycles. In this Account, as a means of studying conjugate-base anions in water, we describe infrared multiple-photon dissociation spectroscopy on clusters in which the sulfate, nitrate, bicarbonate, and suberate anions are hydrated by a known number of water molecules. This spectral technique, used over the range of 550-1800 cm(-1), serves as a structural probe of these clusters. The experiments follow how the solvent network around the conjugate-base anion evolves, one water molecule at a time. We make structural assignments by comparing the experimental infrared spectra to those obtained from electronic structure calculations. Our results show how changes in anion structure, symmetry, and charge state have a profound effect on the structure of the solvent network. Conversely, they indicate how hydration can markedly affect the structure of the anion core in a microhydrated cluster. Some key results include the following. The first few water molecules bind to the anion terminal oxo groups in a bridging fashion, forming two anion-water hydrogen bonds. Each oxo group can form up to three hydrogen bonds; one structural result, for example, is the highly symmetric, fully coordinated SO(4)(2-)(H(2)O)(6) cluster, which only contains bridging water molecules. Adding more water molecules results in the formation of a solvent network comprising water-water hydrogen bonding in addition to hydrogen bonding to the anion. For the nitrate, bicarbonate, and suberate anions, fewer bridging sites are available, namely, three, two, and one (per carboxylate group), respectively. As a result, an earlier onset of water

  7. Spectral investigation of the effect of anion on the stability of non covalent assemblies of 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecine (benzo-15-crown-5) with sodium halides

    NASA Astrophysics Data System (ADS)

    Ghildiyal, Namrata; Pant, Geeta Joshi nee; Rawat, M. S. M.; Singh, Khushboo

    2017-01-01

    A series of complexes of 2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecine (benzo-15-crown-5) with sodium halides was synthesized in acetonitrile. The effect of anion on the stability and spectral properties of complexes of benzo-15-crown-5 with sodium halides was investigated. The synthesis of complexes of sodium fluoride and sodium chloride are reported for the first time. Chloroform was used as solvent to study the assembly in solution state by 1H and 13C NMR techniques. Single crystal diffraction studies on the easily crystallizable bromide complex confirmed 1:1 stoichiometry of the complex. IR and Raman studies provided valuable evidence for a water molecule shared between the crown encapsulated cation and the counter ion to give a solvent shared ion pair (SSIP). The fluorescence spectra of the complexes were obtained in chloroform by excitation at 270 nm to study the effect of complexation on the fluorescent properties of benzo-15-crown-5.

  8. Do CH-Anion and Anion-π Interactions Alter the Mechanism of 2:1 Host-Guest Complexation in Arylethynyl Monourea Anion Receptors?

    PubMed

    Eytel, Lisa M; Gilbert, Annie K; Görner, Paul; Zakharov, Lev N; Johnson, Darren W; Haley, Michael M

    2017-03-23

    Selective tuning of arylethynyl urea scaffolds for anionic guests requires an understanding of preferred binding motifs of the host-guest interaction. To investigate the binding preference of receptors without a pre-organized binding pocket, two electron-deficient phenylacetylene receptors with a single urea moiety have been prepared and were found to bind halides as 2:1 host-guest complexes that feature key CH-anion or anion-π interactions. These supporting interactions also appear to influence the mechanism of the 2:1 binding event.

  9. An ab initio study on anionic aerogen bonds

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Mohammadian-Sabet, Fariba

    2017-01-01

    An ab initio study is carried out to investigate the anionic aerogen bonds in complexes of KrO3, XeO3 and XeOF2 with F-, Cl-, Br-, CN-, NC-, N3-, SH-, SCN-, NCS-, OH- and OCH3- anions. All of the anionic aerogen bonds analyzed here have a partial covalent character. Charge transfer from the anion to the Kr-O or Xe-O σ∗ orbital stabilizes these complexes and leads to a sizable redshift in the corresponding stretching frequencies. The J(Kr-O) or J(Xe-O) spin-spin coupling constants can be regarded as a useful tool for the characterization of strength of the anionic aerogen-bonded complexes.

  10. The adsorption-desorption transition of double-stranded DNA interacting with an oppositely charged dendrimer induced by multivalent anions

    NASA Astrophysics Data System (ADS)

    Jiang, Yangwei; Zhang, Dong; Zhang, Yaoyang; Deng, Zhenyu; Zhang, Linxi

    2014-05-01

    The adsorption-desorption transition of DNA in DNA-dendrimer solutions is observed when high-valence anions, such as hexavalent anions, are added to the DNA-dendrimer solutions. In the DNA-dendrimer solutions with low-valence anions, dendrimers bind tightly with the V-shaped double-stranded DNA. When high-valence anions, such as pentavalent or hexavalent anions, are added to the DNA-dendrimer solutions, the double-stranded DNA chains can be stretched straightly and the dendrimers are released from the double-stranded DNA chains. In fact, adding high-valence anions to the solutions can change the charge spatial distribution in the DNA-dendrimer solutions, and weaken the electrostatic interactions between the positively charged dendrimers and the oppositely charged DNA chains. Adsorption-desorption transition of DNA is induced by the overcharging of dendrimers. This investigation is capable of helping us understand how to control effectively the release of DNA in gene/drug delivery because an effective gene delivery for dendrimers includes non-covalent DNA-dendrimer binding and the effective release of DNA in gene therapy.

  11. The adsorption-desorption transition of double-stranded DNA interacting with an oppositely charged dendrimer induced by multivalent anions.

    PubMed

    Jiang, Yangwei; Zhang, Dong; Zhang, Yaoyang; Deng, Zhenyu; Zhang, Linxi

    2014-05-28

    The adsorption-desorption transition of DNA in DNA-dendrimer solutions is observed when high-valence anions, such as hexavalent anions, are added to the DNA-dendrimer solutions. In the DNA-dendrimer solutions with low-valence anions, dendrimers bind tightly with the V-shaped double-stranded DNA. When high-valence anions, such as pentavalent or hexavalent anions, are added to the DNA-dendrimer solutions, the double-stranded DNA chains can be stretched straightly and the dendrimers are released from the double-stranded DNA chains. In fact, adding high-valence anions to the solutions can change the charge spatial distribution in the DNA-dendrimer solutions, and weaken the electrostatic interactions between the positively charged dendrimers and the oppositely charged DNA chains. Adsorption-desorption transition of DNA is induced by the overcharging of dendrimers. This investigation is capable of helping us understand how to control effectively the release of DNA in gene/drug delivery because an effective gene delivery for dendrimers includes non-covalent DNA-dendrimer binding and the effective release of DNA in gene therapy.

  12. Organic Anion Transporting Polypeptides

    PubMed Central

    Stieger, Bruno; Hagenbuch, Bruno

    2013-01-01

    Organic anion transporting polypeptides or OATPs are central transporters in the disposition of drugs and other xenobiotics. In addition, they mediate transport of a wide variety of endogenous substrates. The critical role of OATPs in drug disposition has spurred research both in academia and in the pharmaceutical industry. Translational aspects with clinical questions are the focus in academia, while the pharmaceutical industry tries to define and understand the role these transporters play in pharmacotherapy. The present overview summarizes our knowledge on the interaction of food constituents with OATPs, and on the OATP transport mechanisms. Further, it gives an update on the available information on the structure-function relationship of the OATPs, and finally, covers the transcriptional and posttranscriptional regulation of OATPs. PMID:24745984

  13. Anion transport and supramolecular medicinal chemistry.

    PubMed

    Gale, Philip A; Davis, Jeffery T; Quesada, Roberto

    2017-04-05

    New approaches to the transmembrane transport of anions are discussed in this review. Advances in the design of small molecule anion carriers are reviewed in addition to advances in the design of synthetic anion channels. The application of anion transporters to the potential future treatment of disease is discussed in the context of recent findings on the selectivity of anion transporters.

  14. Anion-promoted cation motion and conduction in zeolites.

    PubMed

    Jordan, Edgar; Bell, Robert G; Wilmer, Dirk; Koller, Hubert

    2006-01-18

    The motion of sodium cations in sodalite and cancrinite has been investigated by force field calculations, solid-state NMR, and impedance spectroscopy. Special emphasis is dedicated to the influence of anions on sodium mobilities. Local cation motion is promoted when they interact with anions. However, not all systems with high local mobilities exhibit good ion conductivities, as cooperativity of the motion appears to be an important factor, as well. The activation barrier for local sodium motion (calculations) and long-range transport (dc conductivities) is lowered in sodalite when halogenide anions, Cl(-), Br(-), or I(-), are present. The activation barriers increase with increasing size of the anion and decreasing coordination in the transition state. On the basis of (23)Na solid-state NMR data, all the sodium ions in the dense sodalite structure are rather rigid up to 470 K. All the cations in chromate sodalite, and Na(+) in the small cancrinite epsilon-cages without anion interactions, show a restricted local motion at higher temperatures. There is a selective high local motion of Na(+) in the neighborhood of chromate anions in the more open channel system of cancrinite. These results suggest that sodium migration can be enhanced, at least locally, in open channel systems by anion interactions. A dynamics coupling between anion reorientation and cation mobility was not observed.

  15. Photoelectron spectroscopic studies of 5-halouracil anions

    SciTech Connect

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Bowen, Kit H.; Sevilla, Michael D.; Rak, Janusz

    2011-01-07

    The parent negative ions of 5-chlorouracil, UCl{sup -} and 5-fluorouracil, UF{sup -} have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl{sup -} and UF{sup -} and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr{sup -}, we did not observe it, the mass spectrum exhibiting only Br{sup -} fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  16. Photoelectron spectroscopic studies of 5-halouracil anions

    NASA Astrophysics Data System (ADS)

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Sevilla, Michael D.; Rak, Janusz; Bowen, Kit H.

    2011-01-01

    The parent negative ions of 5-chlorouracil, UCl- and 5-fluorouracil, UF- have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl- and UF- and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr-, we did not observe it, the mass spectrum exhibiting only Br- fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  17. Gas-phase chemistry of diphosphate anions as a tool to investigate the intrinsic requirements of phosphate ester enzymatic reactions: the [M1M2HP2O7]- ions.

    PubMed

    Pepi, Federico; Barone, Vincenzo; Cimino, Paola; Ricci, Andreina

    2007-01-01

    Experimental studies on gaseous inorganic phosphate ions are practically nonexistent, yet they can prove helpful for a better understanding of the mechanisms of phosphate ester enzymatic processes. The present contribution extends our previous investigations on the gas-phase ion chemistry of diphosphate species to the [M(1)M(2)HP(2)O(7)](-) ions where M(1) and M(2) are the same or different and correspond to the Li, Na, K, Cs, and Rb cations. The diphosphate ions are formed by electrospray ionization of 10(-4) M solutions of Na(5)P(3)O(10) in CH(3)CN/H(2)O (1/1) and MOH bases or M salts as a source of M(+) cations. The joint application of mass spectrometric techniques and quantum-mechanical calculations makes it possible to characterize the gaseous [M(1)M(2)HP(2)O(7)](-) ions as a mixed ionic population formed by two isomeric species: linear diphosphate anion coordinated to two M(+) cations (group I) and [PO(3)M(1)M(2)HPO(4)](-) clusters (group II). The relative gas-phase stabilities and activation barriers for the isomerization I-->II, which depend on the nature of the M(+) cations, highlight the electronic susceptibility of P-O-P bond breaking in the active site of enzymes. The previously unexplored gas-phase reactivity of [M(1)M(2)HP(2)O(7)](-) ions towards alcohols of different acidity was investigated by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS). The reaction proceeds by addition of the alcohol molecule followed by elimination of a water molecule.

  18. Bound Anionic States of Aadenine

    SciTech Connect

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

    2007-03-20

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. 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,wehave 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 newfound 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 new valence states observed here, unlike the dipole-bound state, could exist in condensed phases and might be relevant to radiobiological damage. The discovery of these valence anionic states of adenine was facilitated by the development of (i) an experimental method for preparing parent anions of nucleic acid bases for photoelectron experiments, and (ii) a combinatorial/quantum chemical approach for identification of the most stable tautomers of organic molecules.

  19. Bound Anionic States of Adenine

    SciTech Connect

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

    2007-03-20

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. 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 newfound 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 new valence states observed here, unlike the dipole-bound state, could exist in condensed phases and might be relevant to radiobiological damage. The discovery of these valence anionic states of adenine was facilitated by the development of (i) an experimental method for preparing parent anions of nucleic acid bases for photoelectron experiments, and (it) a combinatorial/quantum chemical approach for identification of the most stable tautomers of organic molecules.

  20. The benzene radical anion: A computationally demanding prototype for aromatic anions

    SciTech Connect

    Bazante, Alexandre P. Bartlett, Rodney J.; Davidson, E. R.

    2015-05-28

    The benzene radical anion is studied with ab initio coupled-cluster theory in large basis sets. Unlike the usual assumption, we find that, at the level of theory investigated, the minimum energy geometry is non-planar with tetrahedral distortion at two opposite carbon atoms. The anion is well known for its instability to auto-ionization which poses computational challenges to determine its properties. Despite the importance of the benzene radical anion, the considerable attention it has received in the literature so far has failed to address the details of its structure and shape-resonance character at a high level of theory. Here, we examine the dynamic Jahn-Teller effect and its impact on the anion potential energy surface. We find that a minimum energy geometry of C{sub 2} symmetry is located below one D{sub 2h} stationary point on a C{sub 2h} pseudo-rotation surface. The applicability of standard wave function methods to an unbound anion is assessed with the stabilization method. The isotropic hyperfine splitting constants (A{sub iso}) are computed and compared to data obtained from experimental electron spin resonance experiments. Satisfactory agreement with experiment is obtained with coupled-cluster theory and large basis sets such as cc-pCVQZ.

  1. Anion-exchange nanospheres as titration reagents for anionic analytes.

    PubMed

    Zhai, Jingying; Xie, Xiaojiang; Bakker, Eric

    2015-08-18

    We present here anion-exchange nanospheres as novel titration reagents for anions. The nanospheres contain a lipophilic cation for which the counterion is initially Cl(-). Ion exchange takes place between Cl(-) in the nanospheres and a more lipophilic anion in the sample, such as ClO4(-) and NO3(-). Consecutive titration in the same sample solution for ClO4(-) and NO3(-) were demonstrated. As an application, the concentration of NO3(-) in spinach was successfully determined using this method.

  2. Anion selectivity in biological systems.

    PubMed

    Wright, E M; Diamond, J M

    1977-01-01

    As background for appreciating the still-unsolved problems of monovalent anion selectivity, we summarize the facts and intepretations that seem reasonably well established. In section II we saw that specific effects of monovalent anions on biological and physical systems define qualitative patterns, in that only certain sequences of anion effects are observed. For example, the 4 halides can be permitted on paper as 4! = 24 sequences, yet only 5 of these sequences have been observed in nature as potency sequences. In addition, there are quantitative regularities in anion potency that permit the construction of so-called empirical selectivity isotherms (Figs. 4 and 13). That is, a given potency sequence is found to be associated with only a certain modest range of selectivity ratios. The sequences and isotherms apply to effects with a nonequilibrium component (e.g., permeability and conductance sequences) as well as to purely equilibrium effects. Since students of cation selectivity have had difficulty accepting this conclusion, we discuss the reasons why it is not as paradoxical as it at first seems. In sections III and IV we develop four theoretical models to account for the observed anion potency sequences as sequences of equilibrium binding energies. Two of these models involve calculation of electrostatic binding energies between anions and monopolar or dipolar cationic sites, assuming anions as well as sites to be rigid and nonpolarizable. The other two models use thermochemically measured binding energies between anions and thealkali cations or occasionally alkaline-earth cations, which in fact approximate rigid, nonpolarizable spheres. All four models consider the anion selectivity pattern of a given cationic site to be determined by anion differences in the balance between hydration energies and ion-site binding energies. Site differences in anion selectivity pattern are attributed to site differences in radius, charge, coordination number, or dipole length

  3. Supramolecular chemistry of selective anion recognition for anions of environmental relevance. 1998 annual progress report

    SciTech Connect

    Bowman-James, K.; Wilson, G.S.; Kuczera, K.; Moyer, B.

    1998-06-01

    'This project has as its focus the design and synthesis of polyammonium macrocyclic receptors for oxoanions of environmental importance. The basic research aspects of this project involve: (1) synthesis (and the search for improved synthetic methods); (2) solid state structure determination and thermodynamics studies (to ascertain structural criteria for and strength of anion binding); and (3) molecular dynamics simulations (to assess solution characteristics of the interactions between anions and their receptors). Applications-oriented goals include the fabrication of more selective anion-selective electrodes and the use of these compounds in liquid-liquid separations. The latter goal comprises the subcontract with Dr. Bruce Moyer at Oak Ridge National Laboratory. This report summarizes work after 1 year and 7 months of a 3-year project. To date, the authors have focussed on the design and synthesis of selective receptors for nitrate and phosphate.'

  4. Reagent Anions for Charge Inversion of Polypeptide/Protein Cations in the Gas Phase

    PubMed Central

    He, Min; Emory, Joshua F.; McLuckey, Scott A.

    2005-01-01

    Various reagent anions capable of converting polypeptide cations to anions via ion/ion reactions have been investigated. The major charge inversion reaction channels include multiple proton transfer and adduct formation. Dianions composed of sulfonate groups as the negative charge carriers show essentially exclusive adduct formation in converting protonated peptides and proteins to anions. Dianions composed of carboxylate groups, on the other hand, show far more charge inversion via multiple proton transfer, with the degree of adduct formation dependent upon both the size of the polypeptide and the spacings between carboxylate groups in the dianion. More highly charged carboxylate-containing anions, such as those derived from carboxylate-terminated polyamidoamine half-generation dendrimers show charge inversion to give anion charges as high in magnitude as −4, with the degree of adduct formation being inversely related to dendrimer generation. All observations can be interpreted on the basis of charge inversion taking place via a long-lived chemical complex. The lifetime of this complex is related to the strengths and numbers of the interactions of the reactants in the complex. Calculations with model systems are fully consistent with sulfonate groups giving rise to more stable complexes. The kinetic stability of the complex can also be affected by the presence of electrostatic repulsion if it is multiply charged. In general, this situation destabilizes the complex and reduces the likelihood for observation of adducts. The findings highlight the characteristics of multiply charged anions that play roles in determining the nature of charge inversion products associated with protonated peptides and proteins. PMID:15889906

  5. Anion exchangers with branched functional ion exchange layers of different hydrophilicity for ion chromatography.

    PubMed

    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

  6. Aza crown ether compounds as anion receptors

    DOEpatents

    Lee, H.S.; Yang, X.O.; McBreen, J.

    1998-08-04

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI{sup +} ion in alkali metal batteries. 3 figs.

  7. Aza crown ether compounds as anion receptors

    DOEpatents

    Lee, Hung Sui; Yang, Xiao-Oing; McBreen, James

    1998-08-04

    A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI.sup.+ ion in alkali metal batteries.

  8. [Impact of biologically important anions on reactive oxygen species formation in water under the effect of non-ionizing physical agents].

    PubMed

    Gudkov, S V; Ivanov, V E; Karp, O É; Chernikov, A V; Belosludtsev, K N; Bobylev, A G; Astashev, M E; Gapeev, A B; Bruskov, V I

    2014-01-01

    The influence of biologically relevant anions (succinate, acetate, citrate, chloride, bicarbonate, hydroorthophosphate, dihydroorthophosphate, nitrite, nitrate) on the formation of hydrogen peroxide and hydroxyl radicals in water was studied under the effect of non-ionizing radiation: heat, laser light with a wavelength of 632.8 nm, corresponding to the maximum absorption of molecular oxygen, and electromagnetic radiation of extremely high frequencies. It has been established that various anions may both inhibit the formation of reactive oxygen species and increase it. Bicarbonate and sulfate anions included in the biological fluids' and medicinal mineral waters have significant, but opposite effects on reactive oxygen species production. Different molecular mechanisms of reactive oxygen species formation are considered under the action of the investigated physical factors involving these anions, which may influence the biological processes by signal-regulatory manner and provide a healing effect in physical therapy.

  9. Survey of organic acid eluents for anion chromatography

    SciTech Connect

    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. On the correlation between phase evolution of lipoplexes/anionic lipid mixtures and DNA release

    NASA Astrophysics Data System (ADS)

    Caracciolo, Giulio; Pozzi, Daniela; Caminiti, Ruggero; Marchini, Cristina; Montani, Maura; Amici, Augusto; Amenitsch, Heinz

    2007-10-01

    We investigated the structural evolution of three lipoplex formulations when interacting with anionic lipids by synchrotron small angle x-ray diffraction, while the extent of DNA release from lipoplexes by anionic lipids was evaluated by gel electrophoresis. Lipoplexes formed lamellar phases when mixed with anionic dioleoylphosphatidylglycerol (DOPG), while promoting the formation of nonbilayer structures when mixed with anionic dioleoylphosphatidic acid (DOPA). However, lipoplexes exhibited a virtually identical extent of DNA release when mixed with DOPG or DOPA. Thus, the recently proposed correlation between the formation of nonlamellar phases in lipoplex/anionic lipid mixtures and the increase of DNA release does not seem to exist.

  11. Anion transporters and biological systems.

    PubMed

    Gale, Philip A; Pérez-Tomás, Ricardo; Quesada, Roberto

    2013-12-17

    In this Account, we discuss the development of new lipid bilayer anion transporters based on the structure of anionophoric natural products (the prodigiosins) and purely synthetic supramolecular systems. We have studied the interaction of these compounds with human cancer cell lines, and, in general, the most active anion transporter compounds possess the greatest anti-cancer properties. Initially, we describe the anion transport properties of synthetic molecules that are based on the structure of the family of natural products known as the prodiginines. Obatoclax, for example, is a prodiginine derivative with an indole ring that is currently in clinical trials for use as an anti-cancer drug. The anion transport properties of the compounds were correlated with their toxicity toward small cell human lung cancer GLC4 cells. We studied related compounds with enamine moieties, tambjamines, that serve as active transporters. These molecules and others in this series could depolarize acidic compartments within GLC4 cells and trigger apoptosis. In a study of the variation of lipophilicity of a series of these compounds, we observed that, as log P increases, the anion transport efficiency reaches a peak and then decreases. In addition, we discuss the anion transport properties of series of synthetic supramolecular anion receptor species. We synthesized trisureas and thioureas based on the tren backbone, and found that the thiourea compounds effectively transport anions. Fluorination of the pendant phenyl groups in this series of compounds greatly enhances the transport properties. Similar to our earlier results, the most active anion transporters reduced the viability of human cancer cell lines by depolarizing acidic compartments in GLC4 cells and triggering apoptosis. In an attempt to produce simpler transporters that obey Lipinski's Rule of Five, we synthesized simpler systems containing a single urea or thiourea group. Once again the thiourea systems, and in particular

  12. Effect of anionic salts in prepartum diets based on alfalfa.

    PubMed

    Joyce, P W; Sanchez, W K; Goff, J P

    1997-11-01

    This study compared prepartum diets based on grass, alfalfa, or alfalfa and anionic salts to investigate their effect on Ca metabolism, acid-base status, endocrine response, disease incidence, and lactational performance of periparturient dairy cows. Forty-five nonlactating Holstein cows in their last 3 wk of gestation were fed a control diet based on grass hay with a dietary cation-anion difference [expressed as milli-equivalents of ((Na + K) - (Cl + S))/100 g of dietary dry matter] of +30 or diets based on alfalfa with a dietary cation-anion difference of either +35 or -7. Cows fed the diet with the dietary cation-anion difference of -7 had the lowest urine pH prepartum and had the highest concentrations of ionized Ca in blood and total Ca in serum at parturition. Increases in 1,25-(OH)2 vitamin D per unit decrease in total Ca in serum were greatest for cows fed the diet with a dietary cation-anion difference of -7. Also, cows fed this same diet consumed the most dry matter postpartum. Incidences of health disorders were 13% (10 of 75), 12% (9 of 75), and 5% (4 of 75) for cows fed the diets with dietary cation-anion differences of +30, +35, and -7, respectively. Results indicate that alfalfa, when supplemented with anionic salts, is a viable forage for prepartum dairy cows.

  13. A Solid-State 95Mo NMR and Computational Investigation of Dodecahedral and Square Antiprismatic Octacyanomolybdate(IV) Anions: Is the Point-Charge Approximation an Accurate Probe of Local Symmetry?

    SciTech Connect

    Forgeron, Michelle A.; Wasylishen, Roderick E.

    2006-06-21

    Solid-state 95Mo NMR spectroscopy is shown to be an efficient and effective tool for analyzing the diamagnetic octacyanomolybdate(IV) anions, Mo(CN)8 4-, of approximate dodecahedral, D2d, and square antiprismatic, D4d, symmetry. The sensitivity of the Mo magnetic shielding (?) and electric field gradient (EFG) tensors to small changes in the local structure of these anions allows the approximate D2d and D4d Mo(CN)8 4- anions to be readily distinguished. The use of high applied magnetic fields, 11.75, 17.63 and 21.1 T, amplifies the overall sensitivity of the NMR experiment and enables more accurate characterization of the Mo ? and EFG tensors. Although the magnitudes of the Mo ? and EFG interactions are comparable for the D2d and D4d Mo(CN)8 4- anions, the relative values and orientations of the principal components of the Mo ? and EFG tensors give rise to 95Mo NMR line shapes that are significantly different at the fields utilized here. Quantum chemical calculations of the Mo ? and EFG tensors, using zeroth-order regular approximation density functional theory (ZORA DFT) and restricted Hartree-Fock (RHF) methods, have also been carried out and are in good agreement with experiment. The most significant and surprising result from the DFT and RHF calculations is a significant EFG at Mo for an isolated Mo(CN)8 4- anion possessing an ideal square antiprismatic structure; this is contrary to the point-charge approximation, PCA, which predicts a zero EFG at Mo for this structure.

  14. pH and Bicarbonate Effects on Mitochondrial Anion Accumulation

    PubMed Central

    Simpson, David P.; Hager, Steven R.

    1979-01-01

    Mitochondria from rabbit and dog renal cortex were incubated with 1 mM 14C-weak acid anions in media containing low (10 mM) or high (40 mM) concentrations of bicarbonate and the steady-state accumulation of labeled anion in the matrix was measured. In the absence of an energy source, no concentration of 14C-anion in the mitochondrial matrix space was present, but the anion concentration was significantly higher at low- than at high-bicarbonate concentration. Addition of an energy source, usually ascorbate plus tetramethyl-p-phenylenediamine, led to increases in matrix space anion levels and to accentuation of the difference in anion uptake between low- and high-bicarbonate media, so that two to four times as much anion was present at low- than at high-bicarbonate concentrations. The anions affected included substrates for which inner membrane carriers are present in mitochondria, such as citrate, α-ketoglutarate, malate, and glutamate, as well as substances which diffuse passively across the inner membrane such as acetate and formate. When a nonbicarbonate medium buffered with Hepes was used, pH change did not alter anion uptake although anion concentrations exceeding those in the medium still developed when an energy source was present. The difference in mitochondrial anion accumulation between low- and high-bicarbonate levels diminished with decreasing temperature or with increasing anion concentration in the medium. Estimation of intramitochondrial pH with [14C]5,5-dimethyl-oxazolidine-2,4-dione showed that the pH gradient across the inner mitochondrial membrane was significantly greater with 10 than with 40 mM bicarbonate in the medium. A hypothesis is described that relates this effect of pH and bicarbonate on mitochondrial anion accumulation to the very rapid changes in substrate levels in renal cortex, which develop when acute metabolic acidosis or alkalosis is produced in the intact animal. It is suggested that an abrupt fall in systemic pH and bicarbonate

  15. Specific anion effects in Artemia salina.

    PubMed

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Quantitative investigation of bonding characteristics in ternary Zintl anions: charge and energy analysis of [Sn2E(15)(2)(ZnPh)](-) (E(15) = Sb, Bi) and [Sn2Sb5(ZnPh)2](3-).

    PubMed

    Raupach, Marc; Dehnen, Stefanie; Tonner, Ralf

    2014-05-30

    The analysis of chemical bonding in Zintl anions and complexes thereof is mostly based on frontier molecular orbital (FMO) analysis. While this approach delivers remarkable insights, it falls short of providing quantitative measures for chemical bonding in these compounds. Here, we investigate the organozinc-ligated Zintl anions [Sn2E(15)2(ZnPh)](-) (E(15) = Sb, Bi) and [Sn2Sb5(ZnPh)2](3-) with charge and energy analysis methods. Partial charge analysis confirms that natural population analysis is more reliable than the Hirshfeld method for the diffuse charge density of the Zintl anions. In a subsequent step, the combined method energy decomposition analysis with natural orbitals for chemical valence is used to deliver quantitative results for the chemical bond between the organozinc fragment and the Zintl anionic cage. From this analysis, we conclude that the shared-electron description represents the chemical bonding in these compounds more appropriate. The bonding is characterized by a σ-type bond polarized toward the ZnPh fragment and a strong π-donation (15-20% of orbital interaction) into the p-orbitals at zinc. Electrostatic contributions, which are not considered in FMO analyses, make up around two-thirds of the attractive metal-ligand interaction and should not be neglected in the discussion of chemical bonding in these compounds. Usage of ligands with better σ- or π-accepting ability might thus serve to further stabilize the interesting class of compounds with multinary Zintl anions in the future.

  17. Separation of multiply charged anions by capillary electrophoresis using alkyl phosphonium pairing agents.

    PubMed

    Feng, Qing; Wanigasekara, Eranda; Breitbach, Zachary S; Armstrong, Daniel W

    2012-04-01

    Two newly developed UV transparent phosphonium-based cationic reagents were evaluated as background electrolyte additives for capillary electrophoresis for the separation of multiply charged anions, including several complex anions. These cationic reagents showed moderate suppression of the electroosmotic flow, interacted with the analytes to improve their separation and often improved the peak shape. The effects of the additives and their concentration on the separation were studied, as well as the buffer type, pH, and voltage. The dicationic reagent effectively separated eight divalent anions within 17 min and the tetracationic reagent best separated nine trivalent anions, as well as a mixture of all the anions.

  18. Selectivity control in synergistic liquid-liquid anion exchange of univalent anions via structure-specific cooperativity between quaternary ammonium cations and anion receptors.

    PubMed

    Borman, Christopher J; Bonnesen, Peter V; Moyer, Bruce A

    2012-10-02

    Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence on the structure of the alkylammonium cation that suggests a supramolecular cooperative effect. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). Whereas synergism is comparatively weak when either methyltri(C(8,10))alkylammonium chloride (Aliquat 336) or tetraheptylammonium chloride is used with the BTU receptor, synergism between C4P and Aliquat 336 is so pronounced that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias. A thermochemical analysis of synergistic anion exchange has been provided for the first time, resulting in the estimation of binding constants for C4P with the ion pairs of A336(+) with Cl(-), Br(-), OAc(F3)(-), NO(3)(-), and I(-).

  19. Selectivity Control in Synergistic Liquid-Liquid Anion Exchange of Univalent Anions via Structure-Specific Cooperativity between Quaternary Ammonium Cations and Anion Receptors

    SciTech Connect

    Borman, Christopher J; Bonnesen, Peter V; Moyer, Bruce A

    2012-01-01

    Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence upon the structure of the alkylammonium cation. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). C4P has the unique ability in its cone anion-binding conformation to accept an appropriately sized electropositive species in the resulting cup formed by its four electron-rich pyrrole groups, while BTU is not expected to be predisposed for a specific host-guest interaction with the quaternary ammonium cations. It was therefore hypothesized that synergism between C4P and methyltri(C8,10)alkylammonium chloride (Aliquat 336) would be uniquely pronounced owing to insertion of the methyl group of the Aliquat cation into the C4P cup, and we present herein data supporting this expectation. While synergism is comparatively weak for both exchangers with the BTU receptor, synergism between C4P and Aliquat 336 is indeed so strong that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias. A thermochemical analysis of synergistic anion exchange has been provided for the first time, unraveling the observed selectivity behavior and resulting in the estimation of binding constants for C4P with the ion pairs of A336+ with Cl , Br , OAcF3 , NO3 , and I . The uniquely strong positive cooperativity between A336 and C4P underscores the advantage of a supramolecular approach in the design of synergistic anion exchange systems.

  20. Corrective Action Investigation Plan for Corrective Action Unit 204: Storage Bunkers, Nevada Test Site, Nevada (December 2002, Revision No.: 0), Including Record of Technical Change No. 1

    SciTech Connect

    NNSA /NSO

    2002-12-12

    The Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 204 under the Federal Facility Agreement and Consent Order. Corrective Action Unit 204 is located on the Nevada Test Site approximately 65 miles northwest of Las Vegas, Nevada. This CAU is comprised of six Corrective Action Sites (CASs) which include: 01-34-01, Underground Instrument House Bunker; 02-34-01, Instrument Bunker; 03-34-01, Underground Bunker; 05-18-02, Chemical Explosives Storage; 05-33-01, Kay Blockhouse; 05-99-02, Explosive Storage Bunker. Based on site history, process knowledge, and previous field efforts, contaminants of potential concern for Corrective Action Unit 204 collectively include radionuclides, beryllium, high explosives, lead, polychlorinated biphenyls, total petroleum hydrocarbons, silver, warfarin, and zinc phosphide. The primary question for the investigation is: ''Are existing data sufficient to evaluate appropriate corrective actions?'' To address this question, resolution of two decision statements is required. Decision I is to ''Define the nature of contamination'' by identifying any contamination above preliminary action levels (PALs); Decision II is to ''Determine the extent of contamination identified above PALs. If PALs are not exceeded, the investigation is completed. If PALs are exceeded, then Decision II must be resolved. In addition, data will be obtained to support waste management decisions. Field activities will include radiological land area surveys, geophysical surveys to identify any subsurface metallic and nonmetallic debris, field screening for applicable contaminants of potential concern, collection and analysis of surface and subsurface soil samples from biased locations, and step-out sampling to define the extent of

  1. Anionic Derivatives of Perfluorinated Trimethylgold.

    PubMed

    Menjón, Babil; Pérez-Bitrián, Alberto; Martínez-Salvador, Sonia; Baya, Miguel; Casas, José María; Martín, Antonio; Orduna, Jesús

    2017-03-20

    The homoleptic compound [PPh₄][CF₃AuCF₃] cleanly undergoes photoinduced oxidative addition of CF₃I to afford the organogold(III) derivative [PPh₄][(CF₃)₃AuI] in good yield and under mild conditions. This compound provides a convenient entry to the chemistry of the perfluorinated (CF₃)₃Au fragment whose properties are analyzed with the aid of DFT methods and compared with those of the homologous non-fluorinated (CH₃)₃Au moiety. It is found that reductive elimination of CX₃-CX₃ in the former (X = F) requires a much higher energy barrier than in the latter (X = H) and is therefore considerably less favored. This can be considered as one of the main features underlying the significantly higher stability associated to the (CF₃)₃Au fragment and its derivatives. This unsaturated, 14-electron species can be stabilized by coordination of any of the halide ligands, including fluoride. In fact, the whole series of anionic [PPh₄][(CF₃)₃AuX] complexes (X = F, Cl, Br, I, CN) has now been isolated and conveniently characterized. Evidence for intermolecular decomposition pathways upon thermolysis in the condensed phase is presented.

  2. Bound anionic states of adenine

    SciTech Connect

    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

  3. Anion exchange polymer electrolytes

    DOEpatents

    Kim, Yu Seung; Kim, Dae Sik; Lee, Kwan-Soo

    2013-07-23

    Solid anion exchange polymer electrolytes and compositions comprising chemical compounds comprising a polymeric core, a spacer A, and a guanidine base, wherein said chemical compound is uniformly dispersed in a suitable solvent and has the structure: ##STR00001## wherein: i) A is a spacer having the structure O, S, SO.sub.2, --NH--, --N(CH.sub.2).sub.n, wherein n=1-10, --(CH.sub.2).sub.n--CH.sub.3--, wherein n=1-10, SO.sub.2-Ph, CO-Ph, ##STR00002## wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each are independently --H, --NH.sub.2, F, Cl, Br, CN, or a C.sub.1-C.sub.6 alkyl group, or any combination of thereof; ii) R.sub.9, R.sub.10, R.sub.11, R.sub.12, or R.sub.13 each independently are --H, --CH.sub.3, --NH.sub.2, --NO, --CH.sub.nCH.sub.3 where n=1-6, HC.dbd.O--, NH.sub.2C.dbd.O--, --CH.sub.nCOOH where n=1-6, --(CH.sub.2).sub.n--C(NH.sub.2)--COOH where n=1-6, --CH--(COOH)--CH.sub.2--COOH, --CH.sub.2--CH(O--CH.sub.2CH.sub.3).sub.2, --(C.dbd.S)--NH.sub.2, --(C.dbd.NH)--N--(CH.sub.2).sub.nCH.sub.3, where n=0-6, --NH--(C.dbd.S)--SH, --CH.sub.2--(C.dbd.O)--O--C(CH.sub.3).sub.3, --O--(CH.sub.2).sub.n--CH--(NH.sub.2)--COOH, where n=1-6, --(CH.sub.2).sub.n--CH.dbd.CH wherein n=1-6, --(CH.sub.2).sub.n--CH--CN wherein n=1-6, an aromatic group such as a phenyl, benzyl, phenoxy, methylbenzyl, nitrogen-substituted benzyl or phenyl groups, a halide, or halide-substituted methyl groups; and iii) wherein the composition is suitable for use in a membrane electrode assembly.

  4. Boron compounds as anion binding agents for nonaqueous battery electrolytes

    DOEpatents

    Lee, Hung Sui; Yang, Xia-Oing; McBreen, James; Xiang, Caili

    2000-02-08

    Novel fluorinated boron-based compounds which act as anion receptors in non-aqueous battery electrolytes are provided. When added to non-aqueous battery electrolytes, the fluorinated boron-based compounds of the invention enhance ionic conductivity and cation transference number of non-aqueous electrolytes. The fluorinated boron-based anion receptors include borane and borate compounds bearing different fluorinated alkyl and aryl groups.

  5. Poster 3: Anion-molecule reactions in Titan's atmsophere: a laboratory perspective

    NASA Astrophysics Data System (ADS)

    Biennier, Ludovic; Joalland, Baptiste; Jamal-Eddine, Nour; Carles, Sophie; Guillemin, Jean-Claude; Trolez, Yann

    2016-06-01

    Heavy ions discovered in the upper atmosphere of Titan may play some role in the production of aerosols observed at lower altitudes. The composition of the large ions and molecules found in the ionosphere, and their precise formation mechanisms are still largely unknown. This lack of information includes the first steps leading to the production of these species, which govern the growth rate. In particular, negative ion cold chemistry has not been explored systematically. There have been a number of experimental studies conducted to determine the kinetics of anion-neutral reactions, but a fraction only has simultaneously led to the determination of the nature of products and even less to the branching ratio into the different exit channels. In the laboratory, we recently engaged in kinetics studies of anion-molecule reactions starting with the reaction of CN- and C3N- with cyanoacetylene HC3N over the 50-300 K temperature range using the CRESU technique (French acronym standing for Reaction Kinetics in Uniform Supersonic Flow). The results show that the CN- + HC3N reaction contributes directly to the growth of larger anions whereas CN- + HC3N does not. The investigation was recently extended in the laboratory to larger ions and other polar co-reactants. The development of a versatile selected anion source, to be combined with the CRESU apparatus, will be also presented.

  6. Hydrogen in anion vacancies of semiconductors

    SciTech Connect

    Du, Mao-Hua; Singh, David J

    2009-01-01

    Density functional calculations show that, depending on the anion size, hydrogen in anion vacancies of various II-VI semiconductors can be either two-fold or four-fold coordinated, and has either amphoteric or shallow donor character. In general, the multi-coordination of hydrogen in an anion vacancy is the indication of an anionic H, H { ion, in the relatively ionic environment. In more covalent semiconductors, H would form a single cation-H bond in the anion vacancy.

  7. Gas-Grain Models for Interstellar Anion Chemistry

    NASA Technical Reports Server (NTRS)

    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

  8. Gas-Grain Models for Interstellar Anion Chemistry

    NASA Technical Reports Server (NTRS)

    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

  9. GAS-GRAIN MODELS FOR INTERSTELLAR ANION CHEMISTRY

    SciTech Connect

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

    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.

  10. Organic anion uptake by hepatocytes.

    PubMed

    Wolkoff, Allan W

    2014-10-01

    Many of the compounds taken up by the liver are organic anions that circulate tightly bound to protein carriers such as albumin. The fenestrated sinusoidal endothelium of the liver permits these compounds to have access to hepatocytes. Studies to characterize hepatic uptake of organic anions through kinetic analyses, suggested that it was carrier-mediated. Attempts to identify specific transporters by biochemical approaches were largely unsuccessful and were replaced by studies that utilized expression cloning. These studies led to identification of the organic anion transport proteins (oatps), a family of 12 transmembrane domain glycoproteins that have broad and often overlapping substrate specificities. The oatps mediate Na(+)-independent organic anion uptake. Other studies identified a seven transmembrane domain glycoprotein, Na(+)/taurocholate transporting protein (ntcp) as mediating Na(+)-dependent uptake of bile acids as well as other organic anions. Although mutations or deficiencies of specific members of the oatp family have been associated with transport abnormalities, there have been no such reports for ntcp, and its physiologic role remains to be determined, although expression of ntcp in vitro recapitulates the characteristics of Na(+)-dependent bile acid transport that is seen in vivo. Both ntcp and oatps traffic between the cell surface and intracellular vesicular pools. These vesicles move through the cell on microtubules, using the microtubule based motors dynein and kinesins. Factors that regulate this motility are under study and may provide a unique mechanism that can alter the plasma membrane content of these transporters and consequently their accessibility to circulating ligands.

  11. Organic Anion Uptake by Hepatocytes

    PubMed Central

    Wolkoff, Allan W.

    2016-01-01

    Many of the compounds taken up by the liver are organic anions that circulate tightly bound to protein carriers such as albumin. The fenestrated sinusoidal endothelium of the liver permits these compounds to have access to hepatocytes. Studies to characterize hepatic uptake of organic anions through kinetic analyses, suggested that it was carrier-mediated. Attempts to identify specific transporters by biochemical approaches were largely unsuccessful and were replaced by studies that utilized expression cloning. These studies led to identification of the organic anion transport proteins (oatps), a family of 12 transmembrane domain glycoproteins that have broad and often overlapping substrate specificities. The oatps mediate Na+-independent organic anion uptake. Other studies identified a seven transmembrane domain glycoprotein, Na+/taurocholate transporting protein (ntcp) as mediating Na+-dependent uptake of bile acids as well as other organic anions. Although mutations or deficiencies of specific members of the oatp family have been associated with transport abnormalities, there have been no such reports for ntcp, and its physiologic role remains to be determined, although expression of ntcp in vitro recapitulates the characteristics of Na+-dependent bile acid transport that is seen in vivo. Both ntcp and oatps traffic between the cell surface and intracellular vesicular pools. These vesicles move through the cell on microtubules, using the microtubule based motors dynein and kinesins. Factors that regulate this motility are under study and may provide a unique mechanism that can alter the plasma membrane content of these transporters and consequently their accessibility to circulating ligands. PMID:25428858

  12. New stationary phase for anion-exchange chromatography.

    PubMed

    Auler, Lúcia M L A; Silva, César R; Collins, Kenneth E; Collins, Carol H

    2005-05-06

    This work describes the preparation of an anion-exchange phase based on silica, using a two-step modification process. First, 10 microm Davisil silica particles were silanized with chloropropyltrimethoxysilane to yield chloropropyl silica. The modified silica was then reacted with pyridine to produce positively charged propylpyridinium groups on the surface, the anion-exchange sites. The phase was characterized by thermogravimetric analysis and infrared and solid state 13C and 29Si NMR spectroscopies. HPLC separations of common inorganic anions, including chloride, nitrite, bromide and nitrate, were performed using 150 x 3.9 HPLC columns packed with the phase, using a phthalate buffer solution as mobile phase with non-suppressed conductivity detection. Efficiency and resolution were calculated and the results show that the new phase has significant promise for the analysis of these anions in environmental samples.

  13. Pu Anion Exchange Process Intensification

    SciTech Connect

    Taylor-Pashow, K.

    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.

  14. Anions in Nucleic Acid Crystallography.

    PubMed

    D'Ascenzo, Luigi; Auffinger, Pascal

    2016-01-01

    Nucleic acid crystallization buffers contain a large variety of chemicals fitting specific needs. Among them, anions are often solely considered for pH-regulating purposes and as cationic co-salts while their ability to directly bind to nucleic acid structures is rarely taken into account. Here we review current knowledge related to the use of anions in crystallization buffers along with data on their biological prevalence. Chloride ions are frequently identified in crystal structures but display low cytosolic concentrations. Hence, they are thought to be distant from nucleic acid structures in the cell. Sulfate ions are also frequently identified in crystal structures but their localization in the cell remains elusive. Nevertheless, the characterization of the binding properties of these ions is essential for better interpreting the solvent structure in crystals and consequently, avoiding mislabeling of electron densities. Furthermore, understanding the binding properties of these anions should help to get clues related to their potential effects in crowded cellular environments.

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

    SciTech Connect

    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

  16. Poly(1-adamantyl acrylate): Living Anionic Polymerization, Block Copolymerization, and Thermal Properties

    SciTech Connect

    Lu, Wei; Huang, Caili; Hong, Kunlun; Kang, Nam-Goo; Mays, Jimmy W.

    2016-12-06

    Living anionic polymerization of acrylates is challenging due to intrinsic side reactions including backbiting reactions of propagating enolate anions and aggregation of active chain ends. In this study, the controlled synthesis of poly(1-adamatyl acrylate) (PAdA) was performed successfully for the first time via living anionic polymerization through investigation of the initiation systems of sec-butyllithium/diphenylethylene/lithium chloride (sec-BuLi/DPE/LiCl), diphenylmethylpotassium/diethylzinc (DPMK/Et2Zn), and sodium naphthalenide/dipenylethylene/diethylzinc (Na-Naph/DPE/Et2Zn) in tetrahydrofuran at -78 °C using custom glass-blowing and high-vacuum techniques. PAdA synthesized via anionic polymerization using DPMK with a large excess (more than 40-fold to DPMK) of Et2Zn as the ligand exhibited predicted molecular weights from 4.3 to 71.8 kg/mol and polydispersity indices of around 1.10. In addition, the produced PAdAs exhibit a low level of isotactic content (mm triads of 2.1%). The block copolymers of AdA and methyl methacrylate (MMA) were obtained by sequential anionic polymerization, and the distinct living property of PAdA over other acrylates was demonstrated based on the observation that the resulting PAdA-b-PMMA block copolymers were formed with no residual PAdA homopolymer. The PAdA homopolymers exhibit a very high glass transition temperature (133 °C) and outstanding thermal stability (Td: 376 °C) as compared to other acrylic polymers such as poly(tert-butyl acrylate) and poly(methyl acrylate). These merits make PAdA a promising candidate for acrylic-based thermoplastic elastomers with high upper service temperature and enhanced mechanical strength.

  17. Poly(1-adamantyl acrylate): Living Anionic Polymerization, Block Copolymerization, and Thermal Properties

    DOE PAGES

    Lu, Wei; Huang, Caili; Hong, Kunlun; ...

    2016-12-06

    Living anionic polymerization of acrylates is challenging due to intrinsic side reactions including backbiting reactions of propagating enolate anions and aggregation of active chain ends. In this study, the controlled synthesis of poly(1-adamatyl acrylate) (PAdA) was performed successfully for the first time via living anionic polymerization through investigation of the initiation systems of sec-butyllithium/diphenylethylene/lithium chloride (sec-BuLi/DPE/LiCl), diphenylmethylpotassium/diethylzinc (DPMK/Et2Zn), and sodium naphthalenide/dipenylethylene/diethylzinc (Na-Naph/DPE/Et2Zn) in tetrahydrofuran at -78 °C using custom glass-blowing and high-vacuum techniques. PAdA synthesized via anionic polymerization using DPMK with a large excess (more than 40-fold to DPMK) of Et2Zn as the ligand exhibited predicted molecular weights from 4.3more » to 71.8 kg/mol and polydispersity indices of around 1.10. In addition, the produced PAdAs exhibit a low level of isotactic content (mm triads of 2.1%). The block copolymers of AdA and methyl methacrylate (MMA) were obtained by sequential anionic polymerization, and the distinct living property of PAdA over other acrylates was demonstrated based on the observation that the resulting PAdA-b-PMMA block copolymers were formed with no residual PAdA homopolymer. The PAdA homopolymers exhibit a very high glass transition temperature (133 °C) and outstanding thermal stability (Td: 376 °C) as compared to other acrylic polymers such as poly(tert-butyl acrylate) and poly(methyl acrylate). These merits make PAdA a promising candidate for acrylic-based thermoplastic elastomers with high upper service temperature and enhanced mechanical strength.« less

  18. ATP binding cassette modulators control abscisic acid-regulated slow anion channels in guard cells

    PubMed Central

    Leonhardt, N; Vavasseur, A; Forestier, C

    1999-01-01

    In animal cells, ATP binding cassette (ABC) proteins are a large family of transporters that includes the sulfonylurea receptor and the cystic fibrosis transmembrane conductance regulator (CFTR). These two ABC proteins possess an ion channel activity and bind specific sulfonylureas, such as glibenclamide, but homologs have not been identified in plant cells. We recently have shown that there is an ABC protein in guard cells that is involved in the control of stomatal movements and guard cell outward K+ current. Because the CFTR, a chloride channel, is sensitive to glibenclamide and able to interact with K+ channels, we investigated its presence in guard cells. Potent CFTR inhibitors, such as glibenclamide and diphenylamine-2-carboxylic acid, triggered stomatal opening in darkness. The guard cell protoplast slow anion current that was recorded using the whole-cell patch-clamp technique was inhibited rapidly by glibenclamide in a dose-dependent manner; the concentration producing half-maximum inhibition was at 3 &mgr;M. Potassium channel openers, which bind to and act through the sulfonylurea receptor in animal cells, completely suppressed the stomatal opening induced by glibenclamide and recovered the glibenclamide-inhibited slow anion current. Abscisic acid is known to regulate slow anion channels and in our study was able to relieve glibenclamide inhibition of slow anion current. Moreover, in epidermal strip bioassays, the stomatal closure triggered by Ca2+ or abscisic acid was reversed by glibenclamide. These results suggest that the slow anion channel is an ABC protein or is tightly controlled by such a protein that interacts with the abscisic acid signal transduction pathway in guard cells. PMID:10368184

  19. A new polymeric ionic liquid-based magnetic adsorbent for the extraction of inorganic anions in water samples.

    PubMed

    Chen, Lei; Huang, Xiaojia; Zhang, Yong; Yuan, Dongxing

    2015-07-17

    In this work, a novel type of polymeric ionic liquid (PIL)-based magnetic adsorbent was successfully synthesized and applied for the extraction and determination of seven inorganic anions in water samples by coupling with ion chromatography. The new adsorbent was synthesized by simple free radical copolymerization of 1-ally-3-vinylimidazolium chloride, ethylene glycol dimethacrylate and silica-coated magnetite. The adsorbent exhibited well-defined core-shell structure and good magnetic response ability. Furthermore, due to the presence of abundant anion-exchange groups in the PIL, the adsorbent displayed expected extraction performance for anions including F(-), Cl(-), Br(-), NO2(-), NO3(-), PO4(3-) and SO4(2-). Various experimental parameters that could affect the extraction performance, such as the amount of adsorbent, desorption solvent, extraction and desorption time, the pH value of sample solution were investigated in detail. Under the optimized conditions, low limits of detection (S/N=3) and quantification limits (S/N=10) of the proposed method for the target anions were achieved within the range of 0.061-0.73μg/L and 0.19-2.41μg/L, respectively. The repeatability was investigated by evaluating the intra-day, inter-day precisions and batch-to-batch reproducibility with relative standard deviations (RSDs) lower than 11%. At the same time, the method also showed high extraction speed, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was used to detect anions in different water samples successfully. The recoveries were in the range of 71.0-111%, and the RSDs were below 12% in the all cases.

  20. Intramolecular indicator displacement assay for anions: supramolecular sensor for glyphosate.

    PubMed

    Minami, Tsuyoshi; Liu, Yuanli; Akdeniz, Ali; Koutnik, Petr; Esipenko, Nina A; Nishiyabu, Ryuhei; Kubo, Yuji; Anzenbacher, Pavel

    2014-08-13

    One of the well-known strategies for anion sensing is an indicator (dye) displacement assay. However, the disadvantage of the dye displacement assays is the low sensitivity due to the excess of the dye used. To overcome this setback, we have developed an "Intramolecular Indicator Displacement Assay (IIDA)". The IIDAs comprise a receptor and a spacer with an attached anionic chromophore in a single-molecule assembly. In the resting state, the environment-sensitive anionic chromophore is bound by the receptor, while the anionic substrate competes for binding into the receptor. The photophysical properties of the dye exhibit change in fluorescence when displaced by anions, which results in cross-reactive response. To illustrate the concept, we have prepared IID sensors 1 and 2. Here, the characterization of sensors and microtiter arrays comprising the IIDA are reported. The microtiter array including IID sensors 1 and 2 is capable of recognizing biological phosphates in water. The utility of the IIDA approach is demonstrated on sensing of a phosphonate herbicide glyphosate and other biologically important anions such as pyrophosphate in the presence of interferent sodium chloride.

  1. Corrective Action Investigation Plan for Corrective Action Unit 410: Waste Disposal Trenches, Tonopah Test Range, Nevada, Revision 0 (includes ROTCs 1, 2, and 3)

    SciTech Connect

    NNSA /NV

    2002-07-16

    This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 410 under the Federal Facility Agreement and Consent Order. Corrective Action Unit 410 is located on the Tonopah Test Range (TTR), which is included in the Nevada Test and Training Range (formerly the Nellis Air Force Range) approximately 140 miles northwest of Las Vegas, Nevada. This CAU is comprised of five Corrective Action Sites (CASs): TA-19-002-TAB2, Debris Mound; TA-21-003-TANL, Disposal Trench; TA-21-002-TAAL, Disposal Trench; 09-21-001-TA09, Disposal Trenches; 03-19-001, Waste Disposal Site. This CAU is being investigated because contaminants may be present in concentrations that could potentially pose a threat to human health and/or the environment, and waste may have been disposed of with out appropriate controls. Four out of five of these CASs are the result of weapons testing and disposal activities at the TTR, and they are grouped together for site closure based on the similarity of the sites (waste disposal sites and trenches). The fifth CAS, CAS 03-19-001, is a hydrocarbon spill related to activities in the area. This site is grouped with this CAU because of the location (TTR). Based on historical documentation and process know-ledge, vertical and lateral migration routes are possible for all CASs. Migration of contaminants may have occurred through transport by infiltration of precipitation through surface soil which serves as a driving force for downward migration of contaminants. Land-use scenarios limit future use of these CASs to industrial activities. The suspected contaminants of potential concern which have been identified are volatile organic compounds; semivolatile organic compounds; high explosives; radiological constituents including depleted uranium

  2. Development of a TaqMan Array Card for Acute-Febrile-Illness Outbreak Investigation and Surveillance of Emerging Pathogens, Including Ebola Virus

    PubMed Central

    Liu, Jie; Ochieng, Caroline; Wiersma, Steve; Ströher, Ute; Towner, Jonathan S.; Whitmer, Shannon; Nichol, Stuart T.; Moore, Christopher C.; Kersh, Gilbert J.; Kato, Cecilia; Sexton, Christopher; Petersen, Jeannine; Massung, Robert; Hercik, Christine; Crump, John A.; Kibiki, Gibson; Maro, Athanasia; Mujaga, Buliga; Gratz, Jean; Jacob, Shevin T.; Banura, Patrick; Scheld, W. Michael; Juma, Bonventure; Onyango, Clayton O.; Montgomery, Joel M.

    2015-01-01

    Acute febrile illness (AFI) is associated with substantial morbidity and mortality worldwide, yet an etiologic agent is often not identified. Convalescent-phase serology is impractical, blood culture is slow, and many pathogens are fastidious or impossible to cultivate. We developed a real-time PCR-based TaqMan array card (TAC) that can test six to eight samples within 2.5 h from sample to results and can simultaneously detect 26 AFI-associated organisms, including 15 viruses (chikungunya, Crimean-Congo hemorrhagic fever [CCHF] virus, dengue, Ebola virus, Bundibugyo virus, Sudan virus, hantaviruses [Hantaan and Seoul], hepatitis E, Marburg, Nipah virus, o'nyong-nyong virus, Rift Valley fever virus, West Nile virus, and yellow fever virus), 8 bacteria (Bartonella spp., Brucella spp., Coxiella burnetii, Leptospira spp., Rickettsia spp., Salmonella enterica and Salmonella enterica serovar Typhi, and Yersinia pestis), and 3 protozoa (Leishmania spp., Plasmodium spp., and Trypanosoma brucei). Two extrinsic controls (phocine herpesvirus 1 and bacteriophage MS2) were included to ensure extraction and amplification efficiency. Analytical validation was performed on spiked specimens for linearity, intra-assay precision, interassay precision, limit of detection, and specificity. The performance of the card on clinical specimens was evaluated with 1,050 blood samples by comparison to the individual real-time PCR assays, and the TAC exhibited an overall 88% (278/315; 95% confidence interval [CI], 84% to 92%) sensitivity and a 99% (5,261/5,326, 98% to 99%) specificity. This TaqMan array card can be used in field settings as a rapid screen for outbreak investigation or for the surveillance of pathogens, including Ebola virus. PMID:26491176

  3. Anion binding in biological systems

    NASA Astrophysics Data System (ADS)

    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.

  4. Cooperative binding of phosphate anion and a neutral nitrogen donor to alkaline-Earth metal ions. Investigation of group 2 metal-organophosphate interaction in the absence and presence of 1,10-phenanthroline.

    PubMed

    Murugavel, Ramaswamy; Kuppuswamy, Subramaniam; Randoll, Sören

    2008-07-07

    Alkaline-earth metal phosphates containing nitrogen-donor ligands have been prepared by the reaction of alkaline-earth metal acetates M(OAc) 2. xH 2O (M = Mg, Ca, Sr, Ba) with 2,6-diisopropylphenyl phosphate (dippH 2) in the absence and presence of 1,10-phenanthroline (phen). Interaction of strontium or barium acetate with dippH 2 in methanol at room temperature leads to the isolation of ionic phosphates [{M 2(mu-H 2O) 4(H 2O) 10}{dipp} 2].4L [M = Sr, L = CH 3OH ( 1); M = Ba, L = H 2O ( 2)]. The addition of a bidentate nitrogen-donor phen to these reactions leads to the isolation of dinuclear metal phosphates [Mg(dipp)(phen)(CH 3OH) 2] 2 ( 3) and [M(dippH) 2(phen) 2(H 2O)] 2 [M = Ca ( 4), Sr ( 5), Ba ( 6)]. While ionic phosphates 1 and 2 are soluble in water, the predominately covalent dimeric compounds 3- 6 are insoluble in all common solvents including water. The new compounds have been characterized in the solid state by elemental analysis, IR, UV-vis, and emission spectroscopy, and single-crystal X-ray diffraction studies. The cationic part in 1 and 2 is a {M 2(mu-H 2O) 4(H 2O) 10} unit, where each metal ion is surrounded by four bridging and five terminal water molecules as ligands. The dipp anion does not directly bind to the metal ions but is extensively hydrogen-bonded to the cationic unit through the phosphate oxygen and water hydrogen atoms to result in an infinitely layered structure where the hydrophobic aryl group protrudes out of the hydrophilic layer formed by the cationic part and -PO 3 (2-) units. In contrast, compounds 3- 6 are discrete dimeric molecules built around a central M 2O 4P 2 eight-membered ring. While the dippH 2 ligand exists in a doubly deprotonated form in 3, two monodeprotonated dippH 2 ligands are present per metal ion in compounds 4- 6. While 3 prefers only one phen ligand in the metal coordination sphere, two phen ligands chelate each metal ion in 4- 6. The conformations of the eight-membered rings in 3- 6 vary significantly

  5. Photoelectron spectrum of valence anions of uracil and first-principles calculations of excess electron binding energies

    NASA Astrophysics Data System (ADS)

    Bachorz, Rafał A.; Klopper, Wim; Gutowski, Maciej; Li, Xiang; Bowen, Kit H.

    2008-08-01

    The photoelectron spectrum (PES) of the uracil anion is reported and discussed from the perspective of quantum chemical calculations of the vertical detachment energies (VDEs) of the anions of various tautomers of uracil. The PES peak maximum is found at an electron binding energy of 2.4 eV, and the width of the main feature suggests that the parent anions are in a valence rather than a dipole-bound state. The canonical tautomer as well as four tautomers that result from proton transfer from an NH group to a C atom were investigated computationally. At the Hartree-Fock and second-order Møller-Plesset perturbation theory levels, the adiabatic electron affinity (AEA) and the VDE have been converged to the limit of a complete basis set to within +/-1 meV. Post-MP2 electron-correlation effects have been determined at the coupled-cluster level of theory including single, double, and noniterative triple excitations. The quantum chemical calculations suggest that the most stable valence anion of uracil is the anion of a tautomer that results from a proton transfer from N1H to C5. It is characterized by an AEA of 135 meV and a VDE of 1.38 eV. The peak maximum is as much as 1 eV larger, however, and the photoelectron intensity is only very weak at 1.38 eV. The PES does not lend support either to the valence anion of the canonical tautomer, which is the second most stable anion, and whose VDE is computed at about 0.60 eV. Agreement between the peak maximum and the computed VDE is only found for the third most stable tautomer, which shows an AEA of ~-0.1 eV and a VDE of 2.58 eV. This tautomer results from a proton transfer from N3H to C5. The results illustrate that the characteristics of biomolecular anions are highly dependent on their tautomeric form. If indeed the third most stable anion is observed in the experiment, then it remains an open question why and how this species is formed under the given conditions.

  6. Photoelectron spectrum of valence anions of uracil and first-principles calculations of excess electron binding energies.

    PubMed

    Bachorz, Rafał A; Klopper, Wim; Gutowski, Maciej; Li, Xiang; Bowen, Kit H

    2008-08-07

    The photoelectron spectrum (PES) of the uracil anion is reported and discussed from the perspective of quantum chemical calculations of the vertical detachment energies (VDEs) of the anions of various tautomers of uracil. The PES peak maximum is found at an electron binding energy of 2.4 eV, and the width of the main feature suggests that the parent anions are in a valence rather than a dipole-bound state. The canonical tautomer as well as four tautomers that result from proton transfer from an NH group to a C atom were investigated computationally. At the Hartree-Fock and second-order Moller-Plesset perturbation theory levels, the adiabatic electron affinity (AEA) and the VDE have been converged to the limit of a complete basis set to within +/-1 meV. Post-MP2 electron-correlation effects have been determined at the coupled-cluster level of theory including single, double, and noniterative triple excitations. The quantum chemical calculations suggest that the most stable valence anion of uracil is the anion of a tautomer that results from a proton transfer from N1H to C5. It is characterized by an AEA of 135 meV and a VDE of 1.38 eV. The peak maximum is as much as 1 eV larger, however, and the photoelectron intensity is only very weak at 1.38 eV. The PES does not lend support either to the valence anion of the canonical tautomer, which is the second most stable anion, and whose VDE is computed at about 0.60 eV. Agreement between the peak maximum and the computed VDE is only found for the third most stable tautomer, which shows an AEA of approximately -0.1 eV and a VDE of 2.58 eV. This tautomer results from a proton transfer from N3H to C5. The results illustrate that the characteristics of biomolecular anions are highly dependent on their tautomeric form. If indeed the third most stable anion is observed in the experiment, then it remains an open question why and how this species is formed under the given conditions.

  7. Photoelectron Spectrum of Valence Anions of Uracil and First-principles Calculations of Excess Electron Binding Energies

    SciTech Connect

    Bachorz, Rafal A.; Klopper, Willem M.; Gutowski, Maciej S.; Li, Xiang; Bowen, Kit H.

    2008-08-05

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The photoelectron spectrum (PES) of the uracil anion is reported and discussed from the perspective of quantum chemical calculations of the vertical detachment energies (VDEs) of the anions of various tautomers of uracil. The PES peak maximum is found at an electron binding energy of 2.4 eV, and the width of the main feature suggests that the parent anions are in a valence rather than a dipole-bound state. The canonical tautomer as well as four tautomers that result from proton transfer from an NH group to a C atom were investigated computationally. At the Hartree–Fock and second-order Møller-Plesset perturbation theory levels, the adiabatic electron affinity (AEA) and the VDE have been converged to the limit of a complete basis set to within ±1 meV. Post-MP2 electron-correlation effects have been determined at the coupled-cluster level of theory including single, double, and noniterative triple excitations. The quantum chemical calculations suggest that the most stable valence anion of uracil is the anion of a tautomer that results from a proton transfer from N1H to C5. It is characterized by an AEA of 135 meV and a VDE of 1.38 eV. The peak maximum is as much as 1 eV larger, however, and the photoelectron intensity is only very weak at 1.38 eV. The PES does not lend support either to the valence anion of the canonical tautomer, which is the second most stable anion, and whose VDE is computed at about 0.60 eV. Agreement between the peak maximum and the computed VDE is only found for the third most stable tautomer, which shows an AEA of ≈-0.1 eV and a VDE of 2.58 eV. This tautomer results from a proton transfer from N3H to C5. The results illustrate that the characteristics

  8. Gas-phase synthesis of singly and multiply charged polyoxovanadate anions employing electrospray ionization and collision induced dissociation.

    PubMed

    Al Hasan, Naila M; Johnson, Grant E; Laskin, Julia

    2013-09-01

    Electrospray ionization mass spectrometry (ESI-MS) combined with in-source fragmentation and tandem mass spectrometry (MS/MS) experiments were used to generate a wide range of singly and multiply charged vanadium oxide cluster anions including VxOy(n-) and VxOyCl(n-) ions (x = 1-14, y = 2-36, n = 1-3), protonated clusters, and ligand-bound polyoxovanadate anions. The cluster anions were produced by electrospraying a solution of tetradecavanadate, V14O36Cl(L)5 (L = Et4N(+), tetraethylammonium), in acetonitrile. Under mild source conditions, ESI-MS generates a distribution of doubly and triply charged VxOyCl(n-) and VxOyCl(L)((n-1)-) clusters predominantly containing 14 vanadium atoms as well as their protonated analogs. Accurate mass measurement using a high-resolution LTQ/Orbitrap mass spectrometer (m/Δm = 60,000 at m/z 410) enabled unambiguous assignment of the elemental composition of the majority of peaks in the ESI-MS spectrum. In addition, high-sensitivity mass spectrometry allowed the charge state of the cluster ions to be assigned based on the separation of the major from the much less abundant minor isotope of vanadium. In-source fragmentation resulted in facile formation of smaller VxOyCl((1-2)-) and VxOy ((1-2)-) anions. Collision-induced dissociation (CID) experiments enabled systematic study of the gas-phase fragmentation pathways of the cluster anions originating from solution and from in-source CID. Surprisingly simple fragmentation patterns were obtained for all singly and doubly charged VxOyCl and VxOy species generated through multiple MS/MS experiments. In contrast, cluster anions originating directly from solution produced comparatively complex CID spectra. These results are consistent with the formation of more stable structures of VxOyCl and VxOy anions through low-energy CID. Furthermore, our results demonstrate that solution-phase synthesis of one precursor cluster anion combined with gas-phase CID is an efficient approach for the top

  9. Gas-Phase Synthesis of Singly and Multiply Charged Polyoxovanadate Anions Employing Electrospray Ionization and Collision Induced Dissociation

    NASA Astrophysics Data System (ADS)

    Al Hasan, Naila M.; Johnson, Grant E.; Laskin, Julia

    2013-09-01

    Electrospray ionization mass spectrometry (ESI-MS) combined with in-source fragmentation and tandem mass spectrometry (MS/MS) experiments were used to generate a wide range of singly and multiply charged vanadium oxide cluster anions including VxOy n- and VxOyCln- ions (x = 1-14, y = 2-36, n = 1-3), protonated clusters, and ligand-bound polyoxovanadate anions. The cluster anions were produced by electrospraying a solution of tetradecavanadate, V14O36Cl(L)5 (L = Et4N+, tetraethylammonium), in acetonitrile. Under mild source conditions, ESI-MS generates a distribution of doubly and triply charged VxOyCln- and VxOyCl(L)(n-1)- clusters predominantly containing 14 vanadium atoms as well as their protonated analogs. Accurate mass measurement using a high-resolution LTQ/Orbitrap mass spectrometer (m/Δm = 60,000 at m/z 410) enabled unambiguous assignment of the elemental composition of the majority of peaks in the ESI-MS spectrum. In addition, high-sensitivity mass spectrometry allowed the charge state of the cluster ions to be assigned based on the separation of the major from the much less abundant minor isotope of vanadium. In-source fragmentation resulted in facile formation of smaller VxOyCl(1-2)- and VxOy (1-2)- anions. Collision-induced dissociation (CID) experiments enabled systematic study of the gas-phase fragmentation pathways of the cluster anions originating from solution and from in-source CID. Surprisingly simple fragmentation patterns were obtained for all singly and doubly charged VxOyCl and VxOy species generated through multiple MS/MS experiments. In contrast, cluster anions originating directly from solution produced comparatively complex CID spectra. These results are consistent with the formation of more stable structures of VxOyCl and VxOy anions through low-energy CID. Furthermore, our results demonstrate that solution-phase synthesis of one precursor cluster anion combined with gas-phase CID is an efficient approach for the top-down synthesis of a

  10. Intracellular release of fluorescein anion from layered double hydroxide nanoparticles indicating endosomal escape

    NASA Astrophysics Data System (ADS)

    Tanaka, M.; Aisawa, S.; Hidetoshi, H.; Narita, E.; Dong, Q.; Yin, S.; Sato, T.

    2013-12-01

    In recent years, layered double hydroxide (LDH) has been attempted to be applied to a molecular container due to their anion exchange ability, low cytotoxicity and good biocompatibility. In this paper, we investigated the intracellular behaviour of LDH particles in mammalian cells after internalization. Nanoparticles of fluorescein (Fluo) intercalated LDH, Fluo/LDH, were prepared by the coprecipitation followed by subsequent hydrothermal treatment. As-prepared Fluo/LDH particles have the LDH structure and morphology of hexagonal sheet of 100 nm on the average. In addition, Fluo/LDH also exhibited high green fluorescence and low cytotoxicity. By a confocal laser scanning microscopy, the dim green fluorescence was observed throughout cells, including the nucleus. This result indicated that Fluo/LDH released guest anion (Fluo) from LDH structure inside cells. Furthermore, because the fluorescence was observed throughout the cell, Fluo was not retained within endosome structure, i.e., Fluo/LDH was dissolved to release Fluo from endosome.

  11. Probes for anionic cell surface detection

    DOEpatents

    Smith, Bradley D.

    2013-03-05

    Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

  12. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    NASA Astrophysics Data System (ADS)

    Mallick, Arindam; Basak, Durga

    2017-07-01

    Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO2 clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 1020 cm-3 due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  13. Flexibility of inorganic tennis ball structures inducing anion selectivity.

    PubMed

    Kim, Ki-Hyun; Park, Jung Su; Kang, Tae Yi; Oh, Kyungeun; Seo, Mi-Sook; Sohn, Youn Soo; Jun, Moo-Jin; Nam, Wonwoo; Kim, Kwan Mook

    2006-09-18

    Inorganic tennis balls (ITBs), [[{Pt(betmp)(dach)}(2)Cu](2)(X)][X](3) (in which X=ClO(4) (-) (3), NO(3) (-) (4), Cl(-) (5) and Br(-) (6); dach=trans-1,2-diaminocyclohexane and betmp=bisethylthiomethylidenepropanedioate) and [[{Pt(dteym)(dach)}(2)Cu](2)(PF(6))][PF(6)](3) (7; dteym=1,3-dithiepane-2-ylidenemalonate), were prepared as crystals. Investigation of their X-ray crystal structures revealed that shapes of the cavities in ITBs show significant distortions that depend on the properties of the encapsulated anions. The CuCu* distance was observed to be longest in 7 and shortest in 5, the difference between them being 2.05 A. The flexibility of cavity structures of ITBs makes it possible to encapsulate various anions inside the cavity, while their distortions may be a reason for the difference in the encapsulating ability for anions, that is, anion selectivity. Especially, the distortions observed in 7 are so severe that the encapsulating ability of the cavity for PF(6) (-) is very low compared to other anions. The shapes of ITBs with ClO(4) (-) and BF(4) (-) ions inside their cavities are very similar; however, ClO(4) (-) is encapsulated by the cavity better than BF(4) (-), which is explicable by the difference of metal-anion interactions. This structural study on ITBs gives a clue to the origin of the anion selectivity of the cavity in ITBs previously investigated by (19)F NMR spectroscopy of the ITBs in methanol.

  14. Investigation of the performance of fermentation processes using a mathematical model including effects of metabolic bottleneck and toxic product on cells.

    PubMed

    Sriyudthsak, Kansuporn; Shiraishi, Fumihide

    2010-11-01

    A number of recent research studies have focused on theoretical and experimental investigation of a bottleneck in a metabolic reaction network. However, there is no study on how the bottleneck affects the performance of a fermentation process when a product is highly toxic and remarkably influences the growth and death of cells. The present work therefore studies the effect of bottleneck on product concentrations under different product toxicity conditions. A generalized bottleneck model in a fed-batch fermentation is constructed including both the bottleneck and the product influences on cell growth and death. The simulation result reveals that when the toxic product strongly influences the cell growth and death, the final product concentration is hardly changed even if the bottleneck is removed, whereas it is markedly changed by the degree of product toxicity. The performance of an ethanol fermentation process is also discussed as a case example to validate this result. In conclusion, when the product is highly toxic, one cannot expect a significant increase in the final product concentration even if removing the bottleneck; rather, it may be more effective to somehow protect the cells so that they can continuously produce the product. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. Electrochemical reduction of aromatic ketones in 1-butyl-3-methylimidazolium-based ionic liquids in the presence of carbon dioxide: the influence of the ketone substituent and the ionic liquid anion on bulk electrolysis product distribution.

    PubMed

    Zhao, Shu-Feng; Horne, Mike; Bond, Alan M; Zhang, Jie

    2015-07-15

    Electrochemical reduction of aromatic ketones, including acetophenone, benzophenone and 4-phenylbenzophenone, has been undertaken in 1-butyl-3-methylimidazolium-based ionic liquids containing tetrafluoroborate ([BF4](-)), trifluoromethanesulfonate ([TfO](-)) and tris(pentafluoroethyl)trifluorophosphate ([FAP](-)) anions in the presence of carbon dioxide in order to investigate the ketone substituent effect and the influence of the acidic proton on the imidazolium cation (C2-H) on bulk electrolysis product distribution. For acetophenone, the minor products were dimers (<10%) in all ionic liquids, which are the result of acetophenone radical anion coupling. For benzophenone and 4-phenylbenzophenone, no dimers were formed due to steric hindrance. In these cases, even though carboxylic acids were obtained, the main products generated were alcohols (>50%) derived from proton coupled electron transfer reactions involving the electrogenerated radical anions and C2-H. In the cases of both acetophenone and benzophenone, the product distribution is essentially independent of the ionic liquid anion. By contrast, 4-phenylbenzophenone shows a product distribution that is dependent on the ionic liquid anion. Higher yields of carboxylic acids (∼40%) are obtained with [TfO](-) and [FAP](-) anions because in these ionic liquids the C2-H is less acidic, making the formation of alcohol less favourable. In comparison with benzophenone, a higher yield of carboxylic acid (>30% versus ∼15%) was obtained with 4-phenylbenzophenone in all ionic liquids due to the weaker basicity of 4-phenylbenzophenone radical anion.

  16. Binding Hydrated Anions with Hydrophobic Pockets.

    PubMed

    Sokkalingam, Punidha; Shraberg, Joshua; Rick, Steven W; Gibb, Bruce C

    2016-01-13

    Using a combination of isothermal titration calorimetry and quantum and molecular dynamics calculations, we demonstrate that relatively soft anions have an affinity for hydrophobic concavity. The results are consistent with the anions remaining partially hydrated upon binding, and suggest a novel strategy for anion recognition.

  17. Effect of anionic macromolecules on intestinal permeability of furosemide.

    PubMed

    Valizadeh, Hadi; Fahimfar, Hadi; Ghanbarzadeh, Saeed; Islambulchilar, Ziba; Zakeri-Milani, Parvin

    2015-02-01

    Furosemide is an anionic molecule and has very low absorption in gastro intestinal tract. The aim of this study was to investigate the effect of anionic macromolecules on the intestinal permeability of Furosemide. The intestinal permeability of Furosemide was determined using single-pass intestinal perfusion technique in rats. Briefly a jejunal segment of ∼10 cm was isolated and cannulated in both ends for inlet and outlet solution. The perfusate was collected every 10 min and samples were analyzed using the RP-HPLC method. Test samples containing furosemide and two anionic macromolecules, sodium carboxy methyl cellulose and sodium alginate, at different concentrations were used. The obtained data showed that existence of Sodium carboxy methyl cellulose significantly increased the Peff values in all three investigated concentrations (p < 0.05) but sodium alginate only in concentrations <0.1% increased drug permeability. It is concluded that the anionic macromolecules at specific concentrations could alter the permeability of anionic drugs across the biological membranes. Donnan phenomenon and chelating property of macromolecules could be attributed to the observed effect.

  18. Mineral composition analysis: measuring anion uptake and anion concentrations in plant tissues.

    PubMed

    Hawkesford, Malcolm J; Parmar, Saroj; Buchner, Peter

    2013-01-01

    This chapter describes two basic complementary methods relevant to at least three major macronutrients in plants: NO(3)(-), SO(4)(2-), and phosphate. The first method is the simultaneous determination of tissue content of the oxyanions, NO(3)(-), SO(4)(2-), and phosphate by HPLC, and the second is the determination of tissue uptake (transport) capacity for these same oxyanions. NO(3)(-), phosphate, and SO(4)(2-) , as well as other anions including chloride, malate, and nitrite are extracted from milligram quantities of plant tissue and are separated and quantified in a single chromatographic (HPLC) run. Information on uptake (flux) of these same anions through the roots may be obtained using isotopically labeled elements, enabling transport capacity of roots and subsequent translocation to shoot tissues to be determined.

  19. DFT computational study on decarboxylation mechanism of salicylic acid and its derivatives in the anionic state

    NASA Astrophysics Data System (ADS)

    Gao, Lu; Hu, Yanying; Zhang, Huitu; Liu, Yanchun; Song, Zhidan; Dai, Yujie

    2016-07-01

    The mechanisms of the decarboxylation of salicylic acid anion and its ortho substituted derivatives in gas phase and aqueous solution have been investigated by B3LYP method of DFT theory using the 6-31++G (d,p) basis set. The decarboxylation process includes hydrogen transfers from hydroxyl to carboxyl group and from carboxyl to the α-C of the aryl ring. The mechanism suggested is a pseudo-unimolecular decomposition of the salicylic acid anion and the hydrogen transfer from carboxyl to the α-C of the aryl ring is the rate determining step. Compared with the decarboxylation process in gas phase, the energy barriers in aqueous solution approximately declined by 25%-31%with the water mediation of the hydrogen transfer from carboxyl to the α-C of the aryl ring. The effects of substituents at the ortho position on the decarboxylation process were also investigated. Both the electron donating CH3 and withdrawing group NO2 at the ortho position of carboxyl group can further reduce the reaction energy barriers of the decarboxylation of salicylic acid anions.

  20. SU-E-T-109: An Investigation of Including Variable Relative Biological Effectiveness in Intensity Modulated Proton Therapy Planning Optimization for Head and Neck Cancer Patients

    SciTech Connect

    Cao, W; Zaghian, M; Lim, G; Randeniya, K; Mohan, R; Titt, U

    2015-06-15

    Purpose: The current practice of considering the relative biological effectiveness (RBE) of protons in intensity modulated proton therapy (IMPT) planning is to use a generic RBE value of 1.1. However, RBE is indeed a variable depending on the dose per fraction, the linear energy transfer, tissue parameters, etc. In this study, we investigate the impact of using variable RBE based optimization (vRBE-OPT) on IMPT dose distributions compared by conventional fixed RBE based optimization (fRBE-OPT). Methods: Proton plans of three head and neck cancer patients were included for our study. In order to calculate variable RBE, tissue specific parameters were obtained from the literature and dose averaged LET values were calculated by Monte Carlo simulations. Biological effects were calculated using the linear quadratic model and they were utilized in the variable RBE based optimization. We used a Polak-Ribiere conjugate gradient algorithm to solve the model. In fixed RBE based optimization, we used conventional physical dose optimization to optimize doses weighted by 1.1. IMPT plans for each patient were optimized by both methods (vRBE-OPT and fRBE-OPT). Both variable and fixed RBE weighted dose distributions were calculated for both methods and compared by dosimetric measures. Results: The variable RBE weighted dose distributions were more homogenous within the targets, compared with the fixed RBE weighted dose distributions for the plans created by vRBE-OPT. We observed that there were noticeable deviations between variable and fixed RBE weighted dose distributions if the plan were optimized by fRBE-OPT. For organs at risk sparing, dose distributions from both methods were comparable. Conclusion: Biological dose based optimization rather than conventional physical dose based optimization in IMPT planning may bring benefit in improved tumor control when evaluating biologically equivalent dose, without sacrificing OAR sparing, for head and neck cancer patients. The research

  1. Modeling anion adsorption on kaolinite

    SciTech Connect

    Weerasooriya, R.; Wickramarathna, H.U.S.

    1999-05-15

    Anion adsorption onto kaolinite was quantified using the triple layer surface complexation model. Fluoride adsorption data were described by both anion exchange and H-bonded complexation mechanisms. The outer-sphere complexation mechanism was used to describe the weak adsorption of Cl{sup {minus}}, Br{sup {minus}}, and I{sup {minus}} on kaolinite. The F{sup {minus}} adsorption in the presence of Br{sup {minus}} or I{sup {minus}} was decreased over a range of pH 4--5 whereas Cl{sup {minus}} showed a negligible effect. Competition for binding sites appeared to be an important factor in determining the adsorptive behavior of F{sup {minus}} in Br{sup {minus}} or I{sup {minus}} mediated systems.

  2. Anion Solvation in Carbonate Electrolytes

    SciTech Connect

    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.

  3. Polymerization of anionic wormlike micelles.

    PubMed

    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.

  4. Laser cooling of molecular anions.

    PubMed

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

    2015-05-29

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize 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 photodetachment 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.

  5. Ionol (BHT) produces superoxide anion.

    PubMed

    Smirnova, E G; Lyubimov, Yu I; Malinina, T G; Lyubimova, E Yu; Alexandrushkina, N I; Vanyushin, B F; Kolesova, G M; Yaguzhinsky, L S

    2002-11-01

    In aqueous medium etiolated wheat seedlings release superoxide anion (O2*-). Interaction of a synthetic antioxidant, butylated hydroxytoluene (BHT, ionol), with oxygen in the aqueous medium is accompanied by O2*- formation. This suggests that under certain conditions BHT behaves as a prooxidant. A natural antioxidant, superoxide dismutase (SOD), and also a wound healing preparation, emulsified denatured placenta (EDP), do not exhibit the prooxidant properties. In contrast to BHT, they reduce O2*- production by the etiolated wheat seedling system.

  6. Covalent Polymers Containing Discrete Heterocyclic Anion Receptors

    NASA Astrophysics Data System (ADS)

    Rambo, Brett M.; Silver, Eric S.; Bielawski, Christopher W.; Sessler, Jonathan L.

    This chapter covers recent advances in the development of polymeric materials containing discrete heterocyclic anion receptors, and focuses on advances in anion binding and chemosensor chemistry. The development of polymers specific for anionic species is a relatively new and flourishing area of materials chemistry. The incorporation of heterocyclic receptors capable of complexing anions through noncovalent interactions (e.g., hydrogen bonding and electrostatic interactions) provides a route to not only sensitive but also selective polymeric materials. Furthermore, these systems have been utilized in the development of polymers capable of extracting anionic species from aqueous media. These latter materials may lead to advances in water purification and treatment of diseases resulting from surplus ions.

  7. Benzonitrile: Electron affinity, excited states, and anion solvation.

    PubMed

    Dixon, Andrew R; Khuseynov, Dmitry; Sanov, Andrei

    2015-10-07

    We report a negative-ion photoelectron imaging study of benzonitrile and several of its hydrated, oxygenated, and homo-molecularly solvated cluster anions. The photodetachment from the unsolvated benzonitrile anion to the X̃(1)A1 state of the neutral peaks at 58 ± 5 meV. This value is assigned as the vertical detachment energy (VDE) of the valence anion and the upper bound of adiabatic electron affinity (EA) of benzonitrile. The EA of the lowest excited electronic state of benzonitrile, ã(3)A1, is determined as 3.41 ± 0.01 eV, corresponding to a 3.35 eV lower bound for the singlet-triplet splitting. The next excited state, the open-shell singlet Ã(1)A1, is found about an electron-volt above the triplet, with a VDE of 4.45 ± 0.01 eV. These results are in good agreement with ab initio calculations for neutral benzonitrile and its valence anion but do not preclude the existence of a dipole-bound state of similar energy and geometry. The step-wise and cumulative solvation energies of benzonitrile anions by several types of species were determined, including homo-molecular solvation by benzonitrile, hydration by 1-3 waters, oxygenation by 1-3 oxygen molecules, and mixed solvation by various combinations of O2, H2O, and benzonitrile. The plausible structures of the dimer anion of benzonitrile were examined using density functional theory and compared to the experimental observations. It is predicted that the dimer anion favors a stacked geometry capitalizing on the π-π interactions between the two partially charged benzonitrile moieties.

  8. AT Base Pair Anions vs. (9-methyl-A)(1-methyl-T) Base Pair Anions

    SciTech Connect

    Radisic, Dunja; Bowen, Kit H.; Dabkowska, Iwona; Storoniak, Piotr; Rak, Janusz; Gutowski, Maciej S.

    2005-05-04

    The anionic base pairs of adenine and thymine, (AT)-, and 9-methyladenine and 1-methylthymine, (MAMT)-, have been investigated both theoretically and experimentally in a complementary, synergistic study. Calculations on (AT)- found that it had undergone a barrier-free proton transfer (BFPT) similar to that seen in other dimer anion systems and that its structural configuration that was neither Watson-Crick (WC) nor Hoogsteen (HS). The vertical detachment energy (VDE) of (AT)- was determined by anion photoelectron spectroscopy and found to be in agreement with the VDE value predicted by theory for the BFPT mechanism. An AT pair in DNA is structurally immobilized into the WC configuration, in part, by being bonded to the sugars of the double helix. This circumstance was mimicked by methylating the sites on both A and T where these sugars would have been tied, viz., 9-methyladenine and 1-methylthymine. Calculations found no BFPT in (MAMT)- and a resulting (MAMT)- configuration that wa s either HS or WC, with the configurations differing in stability by ca. 2 kcal/mol. The photoelectron spectrum of (MAMT)- occurred at a completely different electron binding energy than had (AT)-. Moreover, the VDE value of (MAMT)- was in agreement with that predicted by theory. The configuration of (MAMT)- and its lack of electron-induced proton transfer are inter-related. While there may be other pathways for electron-induced damage, BFPT in the WC/HS configurations of (AT)- is not feasible.

  9. Extraction of monoclonal antibodies (IgG1) using anionic and anionic/nonionic reverse micelles.

    PubMed

    George, Daliya A; Stuckey, David C

    2010-01-01

    Purification schemes for antibody production based on affinity chromatography are trying to keep pace with increases in cell culture expression levels and many current research initiatives are focused on finding alternatives to chromatography for the purification of Monoclonal antibodies (MAbs). In this article, we have investigated an alternative separation technique based on liquid-liquid extraction called the reverse micellar extraction. We extracted MAb (IgG1) using reverse micelles of an anionic surfactant, sodium bis 2-ethyl-hexyl sulfosuccinate (AOT) and a combination of anionic (AOT) and nonionic surfactants (Brij-30, Tween-85, Span-85) using isooctane as the solvent system. The extraction efficiency of IgG1 was studied by varying parameters, such as pH of the aqueous phase, cation concentration, and type and surfactant concentration. Using the AOT/Isooctane reverse micellar system, we could achieve good overall extraction of IgG1 (between 80 and 90%), but only 30% of the bioactivity of IgG1 could be recovered at the end of the extraction by using its binding to affinity chromatography columns as a surrogate measure of activity. As anionic surfactants were suspected as being one of the reasons for the reduced activity, we decided to combine a nonionic surfactant with an anionic surfactant and then study its effect on the extraction efficiency and bioactivity. The best results were obtained using an AOT/Brij-30/Isooctane reverse micellar system, which gave an overall extraction above 90 and 59% overall activity recovery. An AOT/Tween-85/Isooctane reverse micellar system gave an overall extraction of between 75 and 80% and overall activity recovery of around 40-45%. The results showed that the activity recovery of IgG1 can be significantly enhanced using different surfactant combination systems, and if the recovery of IgG1 can be further enhanced, the technique shows considerable promise for the downstream purification of MAbs.

  10. Vertical detachment energies of anionic thymidine: Microhydration effects

    NASA Astrophysics Data System (ADS)

    Kim, Sunghwan; Schaefer, Henry F.

    2010-10-01

    Density functional theory has been employed to investigate microhydration effects on the vertical detachment energy (VDE) of the thymidine anion by considering the various structures of its monohydrates. Structures were located using a random searching procedure. Among 14 distinct structures of the anionic thymidine monohydrate, the low-energy structures, in general, have the water molecule bound to the thymine base unit. The negative charge developed on the thymine moiety increases the strength of the intermolecular hydrogen bonding between the water and base units. The computed VDE values of the thymidine monohydrate anions are predicted to range from 0.67 to 1.60 eV and the lowest-energy structure has a VDE of 1.32 eV. The VDEs of the monohydrates of the thymidine anion, where the N1H hydrogen of thymine has been replaced by a 2'-deoxyribose ring, are greater by ˜0.30 eV, compared to those of the monohydrates of the thymine anion. The results of the present study are in excellent agreement with the accompanying experimental results of Bowen and co-workers [J. Chem. Phys. 133, 144304 (2010)].

  11. Vertical detachment energies of anionic thymidine: Microhydration effects.

    PubMed

    Kim, Sunghwan; Schaefer, Henry F

    2010-10-14

    Density functional theory has been employed to investigate microhydration effects on the vertical detachment energy (VDE) of the thymidine anion by considering the various structures of its monohydrates. Structures were located using a random searching procedure. Among 14 distinct structures of the anionic thymidine monohydrate, the low-energy structures, in general, have the water molecule bound to the thymine base unit. The negative charge developed on the thymine moiety increases the strength of the intermolecular hydrogen bonding between the water and base units. The computed VDE values of the thymidine monohydrate anions are predicted to range from 0.67 to 1.60 eV and the lowest-energy structure has a VDE of 1.32 eV. The VDEs of the monohydrates of the thymidine anion, where the N(1)[Single Bond]H hydrogen of thymine has been replaced by a 2(')-deoxyribose ring, are greater by ∼0.30 eV, compared to those of the monohydrates of the thymine anion. The results of the present study are in excellent agreement with the accompanying experimental results of Bowen and co-workers [J. Chem. Phys. 133, 144304 (2010)].

  12. Photoinduced Bimolecular Electron Transfer from Cyano Anions in Ionic Liquids.

    PubMed

    Wu, Boning; Liang, Min; Maroncelli, Mark; Castner, Edward W

    2015-11-19

    Ionic liquids with electron-donating anions are used to investigate rates and mechanisms of photoinduced bimolecular electron transfer to the photoexcited acceptor 9,10-dicyanoanthracene (9,10-DCNA). The set of five cyano anion ILs studied comprises the 1-ethyl-3-methylimidazolium cation paired with each of these five anions: selenocyanate, thiocyanate, dicyanamide, tricyanomethanide, and tetracyanoborate. Measurements with these anions dilute in acetonitrile and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide show that the selenocyanate and tricyanomethanide anions are strong quenchers of the 9,10-DCNA fluorescence, thiocyanate is a moderately strong quencher, dicyanamide is a weak quencher, and no quenching is observed for tetracyanoborate. Quenching rates are obtained from both time-resolved fluorescence transients and time-integrated spectra. Application of a Smoluchowski diffusion-and-reaction model showed that the complex kinetics observed can be fit using only two adjustable parameters, D and V0, where D is the relative diffusion coefficient between donor and acceptor and V0 is the value of the electronic coupling at donor-acceptor contact.

  13. Fluorine-Rich Fluorides: New Insights into the Chemistry of Polyfluoride Anions.

    PubMed

    Vent-Schmidt, Thomas; Brosi, Felix; Metzger, Jens; Schlöder, Tobias; Wang, Xuefeng; Andrews, Lester; Müller, Carsten; Beckers, Helmut; Riedel, Sebastian

    2015-07-06

    Polyfluoride anions have been investigated by matrix-isolation spectroscopy and quantum-chemical methods. For the first time the higher polyfluoride anion [F5 ](-) has been observed under cryogenic conditions in neon matrices at 850 cm(-1) . In addition, a new band for the Cs(+) [F3 ](-) complex in neon is reported.

  14. Evaluation of the Repeatability of the Delta Q Duct Leakage Testing TechniqueIncluding Investigation of Robust Analysis Techniques and Estimates of Weather Induced Uncertainty

    SciTech Connect

    Dickerhoff, Darryl; Walker, Iain

    2008-08-01

    The DeltaQ test is a method of estimating the air leakage from forced air duct systems. Developed primarily for residential and small commercial applications it uses the changes in blower door test results due to forced air system operation. Previous studies established the principles behind DeltaQ testing, but raised issues of precision of the test, particularly for leaky homes on windy days. Details of the measurement technique are available in an ASTM Standard (ASTM E1554-2007). In order to ease adoption of the test method, this study answers questions regarding the uncertainty due to changing weather during the test (particularly changes in wind speed) and the applicability to low leakage systems. The first question arises because the building envelope air flows and pressures used in the DeltaQ test are influenced by weather induced pressures. Variability in wind induced pressures rather than temperature difference induced pressures dominates this effect because the wind pressures change rapidly over the time period of a test. The second question needs to answered so that DeltaQ testing can be used in programs requiring or giving credit for tight ducts (e.g., California's Building Energy Code (CEC 2005)). DeltaQ modeling biases have been previously investigated in laboratory studies where there was no weather induced changes in envelope flows and pressures. Laboratory work by Andrews (2002) and Walker et al. (2004) found biases of about 0.5% of forced air system blower flow and individual test uncertainty of about 2% of forced air system blower flow. The laboratory tests were repeated by Walker and Dickerhoff (2006 and 2008) using a new ramping technique that continuously varied envelope pressures and air flows rather than taking data at pre-selected pressure stations (as used in ASTM E1554-2003 and other previous studies). The biases and individual test uncertainties for ramping were found to be very close (less than 0.5% of air handler flow) to those found in

  15. Reorientional dynamics of water molecules in anionic hydration shells

    PubMed Central

    Laage, Damien; Hynes, James T.

    2007-01-01

    Water molecule rotational dynamics within a chloride anion's first hydration shell are investigated through simulations. In contrast to recent suggestions that the ion's hydration shell is rigid during a water's reorientation, we find a labile hydration sphere, consistent with previous assessments of chloride as a weak structure breaker. The nondiffusive reorientation mechanism found involves a hydrogen-bond partner switch with a large amplitude angular jump and the water's departure from the anion's shell. An analytic extended jump model accounts for the simulation results, as well as available NMR and ultrafast spectroscopic data, and resolves the discrepancy between them. PMID:17581877

  16. Isatin phenylhydrazones: anion enhanced photochromic behaviour.

    PubMed

    Cigáň, M; Jakusová, K; Gáplovský, M; Filo, J; Donovalová, J; Gáplovský, A

    2015-11-01

    The photochemical properties of two basic easily synthesized isatin N(2)-phenylhydrazones were investigated. Contrary to the corresponding isatin N(2)-diphenylhydrazones, only Z-isomers were isolated from the reaction mixtures during the synthesis due to their stabilization by intramolecular hydrogen bonding. Although the presence of the C=N double bond creates conditions for the formation of a simple on-off photoswitch, the low photochemical quantum yield and particularly the low switching amplitude in absorbance hamper their photochromic applications. However, the addition of strongly basic anions to phenylhydrazone solutions leads to isatin NH group deprotonation and creates a new diazene T-type Vis-Vis photochromic system with sufficiently separated absorption maxima. Interestingly, although the thermally stable A-form is also photostable in ambient light, its irradiation with a stronger LED source leads to thermally unstable B-form formation which rapidly isomerizes back to the corresponding A-form. The process is reversible and switching cycles can be repeated in both directions. The important advantages of this two-component organic chromophore-inorganic anion photochromic system are its easy synthesis, easy handling due to its insensitivity to room light, easy further structural modification and reversibility. The corresponding photochemical quantum yield, however, remains relatively low (Φ ∼ 0.001). The theoretically calculated properties are in agreement with the obtained experimental results and support the proposed reaction mechanism.

  17. Generation of furazolidone radical anion and its inhibition by glutathione.

    PubMed

    Lax, D; Kukolich, S G

    1992-08-01

    Furazolidone is a nitrofuran drug which causes dilated cardiomyopathy in turkeys and serves as an important model of human dilated cardiomyopathy. Although extensively investigated, the chemical mechanism by which furazolidone produces injury remains unknown. In this work we used electron paramagnetic resonance (EPR) spectroscopy to show that furazolidone was reduced to its corresponding nitro anion radical by ascorbate and hypoxanthine. Glutathione prevented the generation of this anion radical. These results document directly, with EPR spectroscopy, the presence of furazolidone anion radical during biochemical reduction and suggest a protective role of glutathione in furazolidone-induced injury. These data enhance our understanding of furazolidone metabolism and may be useful in defining its role in furazolidone-induced dilated cardiomyopathy.

  18. Anion photoelectron spectroscopy of radicals and clusters

    SciTech Connect

    Travis, Taylor R.

    1999-12-01

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying 2Σ and 2π states of C2nH (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 C2H and C4H. Other radicals studied include NCN and I3. 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 I3 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.

  19. Isobar Separator for Anions: Current status

    NASA Astrophysics Data System (ADS)

    Alary, Jean-François; Javahery, Gholamreza; Kieser, William; Zhao, Xiao-Lei; Litherland, Albert; Cousins, Lisa; Charles, Christopher

    2015-10-01

    The Isobar Separator for Anions (ISA) is an emerging separation technique of isobars applied first to the selective removal of 36S from 36Cl, achieving a relative suppression ratio of 6 orders of magnitude. Using a radio-frequency quadrupole (RFQ) column incorporating low energy gas cells, this innovative technique enables the use of a wide range of low energy ion-molecule reactions and collisional-induced dissociation processes for suppressing specific atomic of molecular anions with a high degree of selectivity. Other elemental pairs (analyte/isobar) successfully separated at AMS level include Ca/K, Sr/(Y, Zr), Cs/Ba, Hf/W and Pu/U. In view of these initial successes, an effort to develop a version of the ISA that can be used as a robust technique for routine AMS analysis has been undertaken. We will discuss the detailed layout of a practical ISA and the functional requirements that a combined ISA/AMS should meet. These concepts are currently being integrated in a pre-commercial ISA system that will be installed soon at the newly established A.E. Lalonde Laboratory in Ottawa, Canada.

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

    NASA Astrophysics Data System (ADS)

    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].

  1. Mixed anion materials and compounds for novel proton conducting membranes

    DOEpatents

    Poling, Steven Andrew; Nelson, Carly R.; Martin, Steve W.

    2006-09-05

    The present invention provides new amorphous or partially crystalline mixed anion chalcogenide compounds for use in proton exchange membranes which are able to operate over a wide variety of temperature ranges, including in the intermediate temperature range of about 100 .degree. C. to 300.degree. C., and new uses for crystalline mixed anion chalcogenide compounds in such proton exchange membranes. In one embodiment, the proton conductivity of the compounds is between about 10.sup.-8 S/cm and 10.sup.-1 S/cm within a temperature range of between about -60 and 300.degree. C. and a relative humidity of less than about 12%..

  2. Organization and function of anionic phospholipids in bacteria.

    PubMed

    Lin, Ti-Yu; Weibel, Douglas B

    2016-05-01

    In addition to playing a central role as a permeability barrier for controlling the diffusion of molecules and ions in and out of bacterial cells, phospholipid (PL) membranes regulate the spatial and temporal position and function of membrane proteins that play an essential role in a variety of cellular functions. Based on the very large number of membrane-associated proteins encoded in genomes, an understanding of the role of PLs may be central to understanding bacterial cell biology. This area of microbiology has received considerable attention over the past two decades, and the local enrichment of anionic PLs has emerged as a candidate mechanism for biomolecular organization in bacterial cells. In this review, we summarize the current understanding of anionic PLs in bacteria, including their biosynthesis, subcellular localization, and physiological relevance, discuss evidence and mechanisms for enriching anionic PLs in membranes, and conclude with an assessment of future directions for this area of bacterial biochemistry, biophysics, and cell biology.

  3. A structural and electrochemical investigation of 1-alkyl-3-methylimidazolium salts of the nitratodioxouranate(VI) anions [[UO2(NO3)2]2(mu 4-C2O4)]2-, [UO2(NO3)3]-, and [UO2(NO3)4]2-.

    PubMed

    Bradley, Antonia E; Hardacre, Christopher; Nieuwenhuyzen, Mark; Pitner, William R; Sanders, David; Seddon, Kenneth R; Thied, Robert C

    2004-04-19

    The properties of the 1-butyl-3-methylimidazolium salt of the dinuclear mu(4)-(O,O,O',O'-ethane-1,2-dioato)bis[bis(nitrato-O,O)dioxouranate(VI)] anion have been investigated using electrochemistry, single-crystal X-ray crystallography, and extended X-ray absorbance fine structure spectroscopy: the anion structures from these last two techniques are in excellent agreement with each other. Electrochemical reduction of the complex leads to the a two-electron metal-centered reduction of U(VI) to U(IV), and the production of UO(2), or a complex containing UO(2). Under normal conditions, this leads to the coating of the electrode with a passivating film. The presence of volatile organic compounds in the ionic liquids 1-alkyl-3-methylimidazolium nitrate (where the 1-alkyl chain was methyl, ethyl, propyl, butyl, pentyl, hexyl, dodecyl, hexadecyl, or octadecyl) during the oxidative dissolution of uranium(IV) oxide led to the formation of a yellow precipitate. To understand the effect of the cation upon the composition and structure of the precipitates, 1-alkyl-3-methylimidazolium salts of a number of nitratodioxouranate(VI) complexes were synthesized and then analyzed using X-ray crystallography. It was demonstrated that the length of the 1-alkyl chain played an important role, not only in the composition of the complex salt, but also in the synthesis of dinuclear anions containing the bridging mu(4)-(O,O,O',O'-ethane-1,2-dioato), or oxalato, ligand, by protecting it from further oxidation.

  4. Phenyl boron-based compounds as anion receptors for non-aqueous battery electrolytes

    DOEpatents

    Lee, Hung Sui; Yang, Xiao-Qing; McBreen, James; Sun, Xuehui

    2002-01-01

    Novel fluorinated boronate-based compounds which act as anion receptors in non-aqueous battery electrolytes are provided. When added to non-aqueous battery electrolytes, the fluorinated boronate-based compounds of the invention enhance ionic conductivity and cation transference number of non-aqueous electrolytes. The fluorinated boronate-based anion receptors include different fluorinated alkyl and aryl groups.

  5. Corrective Action Investigation Plan for Corrective Action Unit 529: Area 25 Contaminated Materials, Nevada Test Site, Nevada, Rev. 0, Including Record of Technical Change No. 1

    SciTech Connect

    U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office

    2003-02-26

    This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 529, Area 25 Contaminated Materials, Nevada Test Site (NTS), Nevada, under the Federal Facility Agreement and Consent Order. CAU 529 consists of one Corrective Action Site (25-23-17). For the purpose of this investigation, the Corrective Action Site has been divided into nine parcels based on the separate and distinct releases. A conceptual site model was developed for each parcel to address the translocation of contaminants from each release. The results of this investigation will be used to support a defensible evaluation of corrective action alternatives in the corrective action decision document.

  6. Boundary condition and soil attribute impacts on anionic surfactant mobility in unsaturated soil

    SciTech Connect

    Allred, B.; Brown, G.O.

    1996-11-01

    Surfactant mobility in unsaturated soil will impact the effectiveness and efficiency of using these compounds for in situ environmental remediation above the water table. For this reason, transient unsaturated column tests were used to study the influence of boundary conditions and soil attributes on anionic surfactant transport. In these tests, aqueous surfactant solutions were injected into the inlet of horizontally mounted soil columns. Two commercial anionic surfactants were used, an alkyl ether sulfate (AES) and a linear alkylbenzene sulfonate (LAS). The overall study was divided into two parts. First, boundary condition effects including injected surfactant solution concentration, initial moisture content, and surfactant application rate were investigated. Increasing the injection solution concentration increased anionic surfactant mobility in the column while changes in the initial soil moisture content and surfactant application rate had no significant impact. Second, the impacts of soil attributes such as texture, dominant exchangeable cation, and resident organic matter were measured. With respect to texture, mobility was found to be greater in a sandy soil as compared with two loamy soils. Both surfactants, especially LAS, were found to be more mobile in a Na{sup +} dominated soil rather than one dominated by Ca{sup +2}. The absence of soil organic matter increased LAS mobility.

  7. Corrective Action Investigation Plan for Corrective Action Unit 536: Area 3 Release Site, Nevada Test Site, Nevada (Rev. 0 / June 2003), Including Record of Technical Change No. 1

    SciTech Connect

    2003-06-27

    This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office's approach to collect the data necessary to evaluate corrective action alternatives (CAAs) appropriate for the closure of Corrective Action Unit (CAU) 536: Area 3 Release Site, Nevada Test Site, Nevada, under the Federal Facility Agreement and Consent Order. Corrective Action Unit 536 consists of a single Corrective Action Site (CAS): 03-44-02, Steam Jenny Discharge. The CAU 536 site is being investigated because existing information on the nature and extent of possible contamination is insufficient to evaluate and recommend corrective action alternatives for CAS 03-44-02. The additional information will be obtained by conducting a corrective action investigation (CAI) prior to evaluating CAAs and selecting the appropriate corrective action for this CAS. The results of this field investigation are to be used to support a defensible evaluation of corrective action alternatives in the corrective action decision document. Record of Technical Change No. 1 is dated 3-2004.

  8. Corrective Action Investigation Plan for Corrective Action Unit 516: Septic Systems and Discharge Points, Nevada Test Site, Nevada, Rev. 0, Including Record of Technical Change No. 1

    SciTech Connect

    2003-04-28

    This Corrective Action Investigation Plan (CAIP) contains the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Sites Office's (NNSA/NSO's) approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 516, Septic Systems and Discharge Points, Nevada Test Site (NTS), Nevada, under the Federal Facility Agreement and Consent Order. CAU 516 consists of six Corrective Action Sites: 03-59-01, Building 3C-36 Septic System; 03-59-02, Building 3C-45 Septic System; 06-51-01, Sump Piping, 06-51-02, Clay Pipe and Debris; 06-51-03, Clean Out Box and Piping; and 22-19-04, Vehicle Decontamination Area. Located in Areas 3, 6, and 22 of the NTS, CAU 516 is being investigated because disposed waste may be present without appropriate controls, and hazardous and/or radioactive constituents may be present or migrating at concentrations and locations that could potentially pose a threat to human health and the environment. Existing information and process knowledge on the expected nature and extent of contamination of CAU 516 are insufficient to select preferred corrective action alternatives; therefore, additional information will be obtained by conducting a corrective action investigation. The results of this field investigation will support a defensible evaluation of corrective action alternatives in the corrective action decision document. Record of Technical Change No. 1 is dated 3/2004.

  9. Vibrational Autodetachment in Nitroalkane Anions

    NASA Astrophysics Data System (ADS)

    Adams, Christopher L.; Weber, J. Mathias

    2010-06-01

    Nitroalkanes have electron affinities ge 1370 cm-1, well below the excitation energies for CH stretching modes, with the excess charge localized on the nitro group. Upon absorption of an IR photon in a CH stretching vibrational mode, the absorbed energy is redistributed in the molecule. If enough energy is transferred to the NO2 stretching/wagging modes, the excess electron residing on the nitro group is emitted. Vibrational autodetachment (VAD) spectra encode information regarding intramolecular vibrational relaxation (IVR) processes leading up to electron emission. We present VAD photoelectron spectroscopy of polyatomic molecular anions and discuss how a VAD photoelectron spectrum can be modeled.

  10. Preparation of a dibenzylated 1,4-diazacyclohexane-derived strong anion-exchange stationary phase.

    PubMed

    Ruan, Juxiang; Zuo, Xiongjun; Lang, Qiwei; Zeng, Zhijian; Li, Chao

    2013-07-05

    This paper reports the preparation of a novel, silica-based, strong anion-exchange stationary phase from a 1,4-diazacyclohexane derivative. To prepare the difunctional strong anion-exchange stationary phase, activated silica beads were first bonded with 3-chloropropyltriethoxysilane and then reacted with 1-methylpiperazine followed by benzyl chloride. The silica beads, the strong anion-exchange stationary phase and its precusors were instrumentally characterized. Aromatic acids were separated with non-aqueous anion-exchange chromatography. After elution with eluant prepared in mixed solvents of water and methanol, the resulting 1,4-diazacyclohexane-derived, difunctional, strong anion-exchange stationary phase exhibited good separation and selectivity for the aromatic acids investigated. The effects of eluant pH, eluant ion concentration and solvent composites on the separations were investigated. Organic acids with different substituents were eluted in order of decreasing dissociation coefficients, with no observable peak shape differences.

  11. Do photolyases need to provide considerable activation energy for the splitting of cyclobutane pyrimidine dimer radical anions?

    PubMed

    Song, Qin-Hua; Tang, Wen-Jian; Ji, Xue-Bao; Wang, Hong-Bo; Guo, Qing-Xiang

    2007-01-01

    cis-syn Cyclobutane pyrimidine dimers, major UV-induced DNA lesions, are efficiently repaired by DNA photolyases. The key step of the repair reaction is a light-driven electron transfer from the FADH(-) cofactor to the dimer; the resulting radical anion splits spontaneously. Whether the splitting reaction requires considerable activation energy is still under dispute. Recent reports show that the splitting reaction of a dimer radical anion has a significant activation barrier (0.45 eV), and so photolyases have to provide considerable energy. However, these results contradict observations that cis-syn dimer radical anions split into monomers at -196 degrees C, and that the full process of DNA photoreactivation was fast (1.5-2 ns). To investigate the activation energies of dimer radical anions, three model compounds 1-3 were prepared. These include a covalently linked cyclobutane thymine dimer and a tryptophan residue (1) or a flavin unit (3), and the covalently linked uracil dimer and tryptophan (2). Their properties of photosensitised splitting of the dimer units by tryptophan or flavin unit were investigated over a large temperature range, -196 to 70 degrees C. The activation energies were obtained from the temperature dependency of splitting reactions for 1 and 2, 1.9 kJ mol(-1) and 0.9 kJ mol(-1) for the thymine and uracil dimer radical anions, respectively. These values are much lower than that obtained for E. coli photolyase (0.45 eV), and are surmountable at -196 degrees C. The activation energies provide support for previous observations that repair efficiencies for uracil dimers are higher than thymine dimers, both in enzymatic and model systems. The mechanisms of highly efficient enzymatic DNA repair are discussed.

  12. A Flight Investigation of the Damping in Roll and Rolling Effectiveness Including Aeroelastic Effects of Rocket Propelled Missile Models Having Cruciform, Triangular, Interdigitated Wings and Tails

    NASA Technical Reports Server (NTRS)

    Hopko, R. N.

    1951-01-01

    The damping in roll and rolling effectiveness of two models of a missile having cruciform, triangular, interdigitated wings and tails have been determined through a Mach number range of 0.8 to 1.8 by utilizing rocket-propelled test vehicles. Results indicate that the damping in roll was relatively constant over the Mach umber range investigated. The rolling effectiveness was essentially constant at low supersonic speeds and increased with increasing mach numbers in excess of 1.4 over the Mach number range investigated. Aeroelastic effects increase the rolling-effectiveness parameters pb/2V divided by delta and decrease both the rolling-moment coefficient due to wing deflection and the damping-in-roll coefficient.

  13. Government, Including: Air Traffic Controllers, Aviation Safety Inspectors, Airspace Systems Inspection Pilots, Accident Investigators, Electronics Technicians, Engineers, Meteorologists. Aviation Careers Series. Revised.

    ERIC Educational Resources Information Center

    Zaharevitz, Walter

    This booklet, one in a series on aviation careers, outlines the variety of careers in aviation available in federal, state, and local governmental agencies. The first part of the booklet provides general information about civil aviation careers with the federal government, including pay scales, job classifications, and working conditions.…

  14. Government, Including: Air Traffic Controllers, Aviation Safety Inspectors, Airspace Systems Inspection Pilots, Accident Investigators, Electronics Technicians, Engineers, Meteorologists. Aviation Careers Series. Revised.

    ERIC Educational Resources Information Center

    Zaharevitz, Walter

    This booklet, one in a series on aviation careers, outlines the variety of careers in aviation available in federal, state, and local governmental agencies. The first part of the booklet provides general information about civil aviation careers with the federal government, including pay scales, job classifications, and working conditions.…

  15. A unique NH-spacer for N-benzamidothiourea based anion sensors. Substituent effect on anion sensing of the ICT dual fluorescent N-(p-dimethylaminobenzamido)-N'-arylthioureas.

    PubMed

    Wu, Fang-Ying; Li, Zhao; Guo, Lin; Wang, Xian; Lin, Meng-Hai; Zhao, Yu-Fen; Jiang, Yun-Bao

    2006-02-21

    A series of N-(p-dimethylaminobenzamido)-N'-(substituted-phenyl)thioureas (substituent = p-CH3, H, p-Cl, p-Br, m-Br, m-NO2, and p-NO2) were designed as anion sensors in order to better understand the -NH-spacer via a substituent effect investigation. In these molecules the dual fluorescent intramolecular charge transfer (ICT) fluorophore p-dimethylaminobenzamide as the signal reporter was linked to the anion-binding site, the thiourea moiety, via an N-N single bond. Correlation of the NMR signals of the aromatic and -NH protons with substituents in these molecules indicated that the N-N single bond stopped the ground-state electronic communication between the signal reporter and the anion-binding site. Dual fluorescence was observed in highly polar solvents such as acetonitrile with the former five derivatives. The fact that the CT emission wavelength and the CT to LE emission intensity ratio of the sensors were independent of the substituent existing in the anion-binding moiety suggested that the substituent electronic effect could not be communicated to the CT fluorophore in the excited-state either. Yet in acetonitrile both the CT dual fluorescence and the absorption of the sensors were found to be highly sensitive toward anions. A conformation change around the N-N bond in the sensor molecules was suggested to occur upon anion binding that established the electronic communication between the signal reporter and the anion-binding site. The anion binding constants of the N-(p-dimethylaminobenzamido)thiourea sensors were found higher than those of the corresponding traditional N-phenylthiourea counterparts and the substituent effect on the anion binding constant was much higher than that in the latter. "-NH-" was shown to be a unique spacer that affords N-benzamidothiourea allosteric anion sensors.

  16. Crystal Structures and Phase Sequences of Metallocenium Salts with Fluorinated Anions: Effects of Molecular Size and Symmetry on Phase Transitions to Ionic Plastic Crystals.

    PubMed

    Mochida, Tomoyuki; Funasako, Yusuke; Ishida, Mai; Saruta, Shingo; Kosone, Takashi; Kitazawa, Takafumi

    2016-10-24

    Sandwich compounds often exhibit various phase transitions, including those to plastic phases. To elucidate the general features of the phase transitions in metallocenium salts, the thermal properties and crystal structures of [Fe(C5 Me5 )2 ]X ([1]X), [Co(C5 Me5 )2 ]X ([2]X), and [Fe(C5 Me4 H)2 ]X ([3]X) have been investigated, where the counter anions (X) are Tf2 N (=(CF3 SO2 )2 N(-) ), OTf (=CF3 SO3(-) ), PF6 , and BF4 . The Tf2 N salts commonly undergo phase transitions from an ordered phase at low temperatures to an anion-disordered phase, followed by a plastic phase and finally melt at high temperatures. All these salts exhibit a phase transition to a plastic phase, and the transition temperature generally decreases with decreasing cation size and increasing anion size. The crystal structures of these salts comprise an alternating arrangement of cations and anions. About half of these salts exhibit phase transitions at low temperatures, which are mostly correlated with the order-disorder of the anion.

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

    SciTech Connect

    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

  18. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. 1. Anions.

    PubMed

    Shkrob, Ilya A; Marin, Timothy W; Chemerisov, Sergey D; Wishart, James F

    2011-04-14

    Room temperature ionic liquids (IL) find increasing use for the replacement of organic solvents in practical applications, including their use in solar cells and electrolytes for metal deposition, and as extraction solvents for the reprocessing of spent nuclear fuel. The radiation stability of ILs is an important concern for some of these applications, as previous studies suggested extensive fragmentation of the constituent ions upon irradiation. In the present study, electron paramagnetic resonance (EPR) spectroscopy has been used to identify fragmentation pathways for constituent anions in ammonium, phosphonium, and imidazolium ILs. Many of these detrimental reactions are initiated by radiation-induced redox processes involving these anions. Scission of the oxidized anions is the main fragmentation pathway for the majority of the practically important anions; (internal) proton transfer involving the aliphatic arms of these anions is a competing reaction. For perfluorinated anions, fluoride loss following dissociative electron attachment to the anion can be even more prominent than this oxidative fragmentation. Bond scission in the anion was also observed for NO(3)(-) and B(CN)(4)(-) anions and indirectly implicated for BF(4)(-) and PF(6)(-) anions. Among small anions, CF(3)SO(3)(-) and N(CN)(2)(-) are the most stable. Among larger anions, the derivatives of benzoate and imide anions were found to be relatively stable. This stability is due to suppression of the oxidative fragmentation. For benzoates, this is a consequence of the extensive sharing of unpaired electron density by the π-system in the corresponding neutral radical; for the imides, this stability could be the consequence of N-N σ(2)σ(*1) bond formation involving the parent anion. While fragmentation does not occur for these "exceptional" anions, H atom addition and electron attachment are prominent. Among the typically used constituent anions, aliphatic carboxylates were found to be the least

  19. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. I. Anions.

    SciTech Connect

    Shkrob, I. A.; Marin, T.; Chemerisov, S.; Wishart, J.

    2011-04-14

    Room temperature ionic liquids (IL) find increasing use for the replacement of organic solvents in practical applications, including their use in solar cells and electrolytes for metal deposition, and as extraction solvents for the reprocessing of spent nuclear fuel. The radiation stability of ILs is an important concern for some of these applications, as previous studies suggested extensive fragmentation of the constituent ions upon irradiation. In the present study, electron paramagnetic resonance (EPR) spectroscopy has been used to identify fragmentation pathways for constituent anions in ammonium, phosphonium, and imidazolium ILs. Many of these detrimental reactions are initiated by radiation-induced redox processes involving these anions. Scission of the oxidized anions is the main fragmentation pathway for the majority of the practically important anions; (internal) proton transfer involving the aliphatic arms of these anions is a competing reaction. For perfluorinated anions, fluoride loss following dissociative electron attachment to the anion can be even more prominent than this oxidative fragmentation. Bond scission in the anion was also observed for NO{sub 3}{sup -} and B(CN){sub 4}{sup -} anions and indirectly implicated for BF{sub 4}{sup -} and PF{sub 6}{sup -} anions. Among small anions, CF{sub 3}SO{sub 3}{sup -} and N(CN){sub 2}{sup -} are the most stable. Among larger anions, the derivatives of benzoate and imide anions were found to be relatively stable. This stability is due to suppression of the oxidative fragmentation. For benzoates, this is a consequence of the extensive sharing of unpaired electron density by the {pi}-system in the corresponding neutral radical; for the imides, this stability could be the consequence of N-N {sigma}{sup 2}{sigma}*{sup 1} bond formation involving the parent anion. While fragmentation does not occur for these 'exceptional' anions, H atom addition and electron attachment are prominent. Among the typically used

  20. Orientational Jumps in (Acetamide + Electrolyte) Deep Eutectics: Anion Dependence.

    PubMed

    Das, Suman; Biswas, Ranjit; Mukherjee, Biswaroop

    2015-08-27

    All-atom molecular dynamics simulations have been carried out to investigate orientation jumps of acetamide molecules in three different ionic deep eutectics made of acetamide (CH3CONH2) and lithium salts of bromide (Br(–)), nitrate (NO3(–)) and perchlorate (ClO4(–)) at approximately 80:20 mole ratio and 303 K. Orientational jumps have been dissected into acetamide–acetamide and acetamide–ion catagories. Simulated jump characteristics register a considerable dependence on the anion identity. For example, large angle jumps are relatively less frequent in the presence of NO3(–) than in the presence of the other two anions. Distribution of jump angles for rotation of acetamide molecules hydrogen bonded (H-bonded) to anions has been found to be bimodal in the presence of Br(–) and is qualitatively different from the other two cases. Estimated energy barrier for orientation jumps of these acetamide molecules (H-bonded to anions) differ by a factor of ∼2 between NO3(–) and ClO4(–), the barrier height for the latter being lower and ∼0.5kBT. Relative radial and angular displacements during jumps describe the sequence ClO(4)– > NO3(–) > Br(–) and follow a reverse viscosity trend. Jump barrier for acetamide–acetamide pairs reflects weak dependence on anion identity and remains closer to the magnitude (∼0.7kBT) found for orientation jumps in molten acetamide. Jump time distributions exhibit a power law dependence of the type, P(tjump) ∝ A(tjump/τ)(−β), with both β and τ showing substantial anion dependence. The latter suggests the presence of dynamic heterogeneity in these systems and supports earlier conclusions from time-resolved fluorescence measurements.

  1. Pyrazole complexes as anion receptors.

    PubMed

    Nieto, Sonia; Pérez, Julio; Riera, Lucía; Riera, Víctor; Miguel, Daniel

    2006-03-01

    The behavior of the receptors [Re(CO)3(Hdmpz)3]BAr'4 (Hdmpz = 3,5-dimethylpyrazole) (1) and [Re(CO)3(HtBupz)3]BAr'4 (HtBupz = 3(5)-tert-butylpyrazole) (2; Ar' = 3,5-bis(trifluoromethyl)phenyl) toward the anions fluoride, chloride, bromide, iodide, hydrogensulfate, dihydrogenphosphate, nitrate, and perrhenate was studied in CD3CN solution. In most cases, the receptors were stable. Anion exchange was fast, and binding constants were calculated from the NMR titration profiles. The structure of the adduct [Re(CO)3(HtBupz)3] x NO3 (3) was determined by X-ray diffraction. Two pyrazole moieties are hydrogen-bonded to one nitrate oxygen atom, and the third pyrazole moiety is hydrogen-bonded to an oxygen atom of an adjacent nitrate, leading to infinite chains. The structure of the adduct [Re(CO)3(Hdmpz)3]BAr'4acetone (4), also determined by X-ray diffraction, showed a similar interaction of two pyrazole N-H groups with the acetone oxygen atom. F- and H2PO4(-) deprotonate the receptors, and HSO4(-) decomposed 1. The structure of one of the decomposition products (5), determined by X-ray diffraction, is consistent with pyrazole protonation and substitution by sulfate.

  2. Structural evolution of small ruthenium cluster anions

    SciTech Connect

    Waldt, Eugen; Hehn, Anna-Sophia; Ahlrichs, Reinhart; Kappes, Manfred M.; Schooss, Detlef

    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.

  3. Advanced polymer chemistry of organometallic anions

    SciTech Connect

    Chamberlin, R.M.; Abney, K.D.; Balaich, G.J.; Fino, S.A.

    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.

  4. Condom Breakage Among Young Black Men Who Have Sex With Men: An In-Depth Investigation Including Men Living With HIV/AIDS.

    PubMed

    Crosby, Richard A; Mena, Leandro

    2016-02-01

    Correlates of condom breakage (reported by 19% of 398 young black who have sex with men) for anal insertive sex included the following: condoms drying out (P = 0.018), erection loss during application (P = 0.03), and using erection-enhancing drugs (P = 0.003). Breakage was 2.7 times greater for HIV-positive men (P = 0.001). Breakage was associated with testing positive for urethral infections (P = 0.012).

  5. 1978-1979 Cultural Resource Investigations along the Middle Sheyenne River Valley Including Lake Ashtabula and a Portion of the Sheyenne River. Volume 1,

    DTIC Science & Technology

    1980-07-01

    set forth in the Historic Preservation Act of 1966 (P. L. 89-665), the National Environmental Policy Act of 1969 (P. L. 91-190), Executive Order 11593...Basin in North Dakota, including the survey area. The result was an excellent compilation of the paleo- and modern [ environmental setting and previous...hindrance of snow. The reexamination confirmed the earlier finding of nc cultural rescurcc3. Finally, the Lake Ashtabula Environmental Impact Assessment

  6. Investigations to determine whether Section XI of the ASME (American Society of Mechanical Engineers) Boiler and Pressure Vessel Code should include PLEX (plant life extension) baseline inspection guidance

    SciTech Connect

    Bustard, L.D.

    1988-01-01

    A plant life extension (PLEX) issue repeatedly mentioned is whether special PLEX supplemental inspection requirements should be added to Section XI of the ASME Boiler and Pressure Vessel Code. To assist the ASME answer this question, the DOE Technology Management Center performed an industry survey to assess whether there was a technical consensus regarding the desirability and scope of a supplemental PLEX baseline inspection. This survey demonstrated the lack of an initial industry consensus. In response to the survey results, ASME has formed a task group to investigate various PLEX supplemental inspection strategies and to assess their value and liabilities. The results of the survey and initial task group activities are reviewed.

  7. Investigation of cation (Sn2+) and anion (N3-) substitution in favor of visible light photocatalytic activity in the layered perovskite K2La2Ti3O10.

    PubMed

    Kumar, Vinod; Govind; Uma, S

    2011-05-15

    Noticeable lowering of the energy gaps have been achieved for the layered perovskite K(2)La(2)Ti(3)O(10) as a result of the attempts made to incorporate Sn(2+) and N(3-) ions. Incorporation of Sn(2+) ions was carried out by the ion-exchange reaction of K(2)La(2)Ti(3)O(10) with aqueous tin(II) chloride solution. Nitrogen incorporation was attempted by the solid state reaction of the parent oxide with urea around 400 °C in air. The resultant oxides have been characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. Room temperature ion-exchange was sufficient to introduce Sn(2+) ions with the resulting product of composition (Sn(0.45)K(0.2)H(0.9))La(2)Ti(3)O(10) · H(2)O. Visible light absorption was observed with the absorption edge red shift of ∼ 100 nm from that of the parent K(2)La(2)Ti(3)O(10). The lowering of the band gap was as expected by the contribution of Sn 5s orbitals to the O 2p orbitals in the formation of the valence band. Nitridation using urea resulted not only in nitrogen doping but with the additional sensitization by the presence of carbon nitride (CN) polymers, which again resulted in visible light absorption. The product oxides obtained as a result of cation and anion intended substitutional studies have been found to be useful for the visible light photocatalytic decomposition of organic dyes such as rhodamine B. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Using Multiple Approaches, including δ18O Signatures of Phosphate to Investigate Potential Phosphorus Limitation and Cycling under Changing Climate Conditions

    NASA Astrophysics Data System (ADS)

    Roberts, K.; Paytan, A.; Field, C. B.; Honn, E.; Edwards, E.; Gottlieb, R.

    2012-12-01

    Phosphorus (P) is often a limiting or co-limiting nutrient in terrestrial systems. It has been proposed that it will play an even greater role in ecosystems experiencing some of the many predicted effects of climate change, in particular release from nitrogen limitation. Recent work in 2007 by Menge et al. suggests that this is indeed a possibility. To investigate the potential for P limitation, and P cycling under multiple controlled conditions we collected samples from the Jasper Ridge Global Change Experiment (JRGCE) in May 2011. For over a decade the JRGCE has been manipulating four key parameters predicted to change in the future in a native Californian grassland system. Elevated Nitrogen deposition, increased precipitation, increased pCO2, and increased temperature are applied and monitored in a split plot design at the Jasper Ridge Biological Preserve in the eastern foothills of the Santa Cruz Mountains, California. Work done previously at the site using a suite of indicators of the potential P limitation suggest P limitation in some of the manipulated plots in the JRGCE. In this study we replicate a subset of the prior analyses to compare inter-annual signals of P limitation, and further attempt to utilize the oxygen isotopes of phosphate to investigate P cycling in soils at JRGCE. A fractional soil extraction process for phosphate enables separation of several operationally defined P pools, and provides auxiliary information regarding the relative concentrations of bio-available P, and relevant minerals in this grassland system under the varied conditions.

  9. Tunable electronic interactions between anions and perylenediimide.

    PubMed

    Goodson, Flynt S; Panda, Dillip K; Ray, Shuvasree; Mitra, Atanu; Guha, Samit; Saha, Sourav

    2013-08-07

    Over the past decade anion-π interaction has emerged as a new paradigm of supramolecular chemistry of anions. Taking advantage of the electronic nature of anion-π interaction, we have expanded its boundaries to charge-transfer (CT) and formal electron transfer (ET) events by adjusting the electron-donating and accepting abilities of anions and π-acids, respectively. To establish that ET, CT, and anion-π interactions could take place between different anions and π-acids as long as their electronic and structural properties are conducive, herein, we introduce 3,4,9,10-perylenediimide (PDI-1) that selectively undergoes thermal ET from strong Lewis basic hydroxide and fluoride anions, but remains electronically and optically silent to poor Lewis basic anions, as ET and CT events are turned OFF. These interactions have been fully characterized by UV/Vis, NMR, and EPR spectroscopies. These results demonstrate the generality of anion-induced ET events in aprotic solvents and further refute a notion that strong Lewis basic hydroxide and fluoride ions can only trigger nucleophilic attack to form covalent bonds instead of acting as sacrificial electron donors to π-acids under appropriate conditions.

  10. New preconditioning strategy for the determination of inorganic anions with capillary zone electrophoresis using indirect UV detection.

    PubMed

    Raber, G; Greschonig, H

    2000-08-25

    It is widely accepted that preconditioning procedures are indispensable in capillary electrophoresis in order to achieve reproducibility of migration times and peak areas. Several preconditioning strategies have been employed for electrophoretic determinations of inorganic anions using indirect UV detection including simple flushing with buffer or alkaline or acid pre-rinsing followed by flushing with electrolyte. We investigated the influence of various preconditioning strategies on the reproducibility of migration times and peak areas of inorganic anions. The electrolyte systems for indirect UV detection were based on pyromellitic acid and chromic acid respectively as UV absorbing probes and hexamethonium hydroxide as electroosmatic flow modifier. Preconditioning agents under investigation were electrolyte buffer, NaOH, HCl and the free acids of the UV absorbing probes. Investigations showed that reproducibility of migration times and peak areas can be significantly improved by acid pre-rinsing using the corresponding acid of the UV absorbing probes compared to preconditioning by flushing the capillary with buffer. In contrast to acid pre-rinsing using hydrochloric acid no interfering signals within the migration time window of inorganic anions under investigation can be observed. The optimized preconditioning procedure yields relative standard deviations of migration times less than 0.25% (n = 10). Relative standard deviations of corrected peak areas were below 5% applying acid preconditioning using pyromellitic acid.

  11. Investigation of High-Subsonic Performance Characteristics of a 12 Degree 21-Inch Conical Diffuser, Including the Effects of Change in Inlet-Boundary-Layer Thickness

    NASA Technical Reports Server (NTRS)

    Copp, Martin R.; Klevatt, Paul L.

    1950-01-01

    Investigations were conducted of a 12 degree 21-inch conical diffuser of 2:l area ratio to determine the interrelation of boundary layer growth and performance characteristics. surveys were made of inlet and exit from, longitudinal static pressures were recorded, and velocity profiles were obtained through an inlet Reynolds number range, determined From mass flows and based on inlet diameter of 1.45 x 10(exp 6) to 7.45 x 10(exp 6) and a Mach number range of 0.11 to approximately choking. These investigations were made to two thicknesses of inlet boundary layer. The mean value, over the entire range of inlet velocities, of the displacement thickness of the thinner inlet boundary layer was approximately 0.035 inch and that of the thicker inlet boundary layer was approximately six times this value. The loss coefficient in the case of the thinner inlet boundary layer had a value between 2 to 3 percent of the inlet impact pressure over most of the air-flow range. The loss coefficient with the thicker inlet boundary layer was of the order of twice that of the thinner inlet boundary layer at low speeds and approximately three times at high speeds. In both cases the values were substantially less than those given in the literature for fully developed pipe flow. The static-pressure rise for the thinner inlet boundary layer was of the order of 95 percent of that theoretically possible over the entire speed range. For the thicker inlet boundary layer the static pressure rise, as a percentage of that theoretically possible, ranged from 82 percent at low speeds to 68 percent at high speeds.

  12. Once upon anion: a tale of photodetachment.

    PubMed

    Lineberger, W Carl

    2013-01-01

    This contribution is very much a personal history of a journey through the wonderful world of anion chemistry, and a tale of how advances in laser technologies, theoretical methods, and computational capabilities continuously enabled advances in our understanding. It is a story of the excitement and joy that come from the opportunity to add to the fabric of science, and to do so by working as a group of excited explorers with common goals. The participants in this journey include me, my students and postdoctoral associates, my collaborators, and our many generous colleagues. It all happened, in the words of the Beatles, "with a little help from my friends." Actually, it was so much more than a little help!

  13. Once upon Anion: A Tale of Photodetachment

    NASA Astrophysics Data System (ADS)

    Lineberger, W. Carl

    2013-04-01

    This contribution is very much a personal history of a journey through the wonderful world of anion chemistry, and a tale of how advances in laser technologies, theoretical methods, and computational capabilities continuously enabled advances in our understanding. It is a story of the excitement and joy that come from the opportunity to add to the fabric of science, and to do so by working as a group of excited explorers with common goals. The participants in this journey include me, my students and postdoctoral associates, my collaborators, and our many generous colleagues. It all happened, in the words of the Beatles, “with a little help from my friends.” Actually, it was so much more than a little help!

  14. Living anionic polymerization using a microfluidic reactor

    SciTech Connect

    Iida, Kazunori; Chastek, Thomas Q.; Beers, Kathryn L.; Cavicchi, Kevin A.; Chun, Jaehun; Fasolka, Michael J.

    2009-02-01

    Living anionic polymerizations were conducted within aluminum-polyimide microfluidic devices. Polymerizations of styrene in cyclohexane were carried out at various conditions, including elevated temperature (60 °C) and high monomer concentration (42%, by volume). The reactions were safely maintained at a controlled temperature at all points in the reactor. Conducting these reactions in a batch reactor results in uncontrolled heat generation with potentially dangerous rises in pressure. Moreover, the microfluidic nature of these devices allows for flexible 2D designing of the flow channel. Four flow designs were examined (straight, periodically pinched, obtuse zigzag, and acute zigzag channels). The ability to use the channel pattern to increase the level of mixing throughout the reactor was evaluated. When moderately high molecular mass polymers with increased viscosity were made, the patterned channels produced polymers with narrower PDI, indicating that passive mixing arising from the channel design is improving the reaction conditions.

  15. Living anionic polymerization using a microfluidic reactor.

    PubMed

    Iida, Kazunori; Chastek, Thomas Q; Beers, Kathryn L; Cavicchi, Kevin A; Chun, Jaehun; Fasolka, Michael J

    2009-01-21

    Living anionic polymerizations were conducted within aluminum-polyimide microfluidic devices. Polymerizations of styrene in cyclohexane were carried out at various conditions, including elevated temperature (60 degrees C) and high monomer concentration (42%, by volume). The reactions were safely maintained at a controlled temperature at all points in the reactor. Conducting these reactions in a batch reactor results in uncontrolled heat generation with potentially dangerous rises in pressure. Moreover, the microfluidic nature of these devices allows for flexible 2D designing of the flow channel. Four flow designs were examined (straight, periodically pinched, obtuse zigzag, and acute zigzag channels). The ability to use the channel pattern to increase the level of mixing throughout the reactor was evaluated. When moderately high molecular mass polymers with increased viscosity were made, the patterned channels produced polymers with narrower PDI, indicating that passive mixing arising from the channel design is improving the reaction conditions.

  16. Anion exchange resins: Structure, formulation, and applications. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    Not Available

    1994-07-01

    The bibliography contains citations concerning the formulation and synthesis of anion exchange resins based on such resins as amides, polyethylenes, and styrenes. Osmotic, sorption, and electrical properties; exchange kinetics behavior; structure studies; and temperature related performance effects on anion exchange resins are considered. Anion exchange chromatography of liquids, and applications in water purification, pollution control, and protein and metallic ion separation are included. (Contains a minimum of 222 citations and includes a subject term index and title list.)

  17. Investigation of pyrrolizidine alkaloids including their respective N-oxides in selected food products available in Hong Kong by liquid chromatography electrospray ionisation mass spectrometry.

    PubMed

    Chung, Stephen W C; Lam, Aaron C H

    2017-07-01

    This study determined the levels of pyrrolizidine alkaloids (PAs), including their respective N-oxides, in foodstuffs available in Hong Kong by liquid chromatography-electrospray ionisation tandem mass spectrometry. A total of 234 samples (48 food items) were collected randomly from a local market and analysed. About 50% of samples were found to contain detectable amount of PAs. Amongst the 48 food items, PAs were not detected in 11 food items, including barley flour, beef, cattle liver, pork, pig liver, chicken meat, chicken liver, milk, non-fermented tea, Melissa tea and linden tea. For those found to contain detectable PAs, the summed PA content ranged up to 11,000 µg kg(-1). The highest sum of PA content among the 37 food items calculated with lower bound was cumin seed, then followed by oregano, tarragon and herbs de Provence with ranges of 2.5-11,000, 1.5-5100, 8.0-3300 and 18-1300 µg kg(-1) respectively. Among the samples, the highest sum of PA content was detected in a cumin seed sample (11,000 µg kg(-1)), followed by an oregano (5100 µg kg(-1)), a tarragon (3300 µg kg(-1)) and a herbs de Provence (1300 µg kg(-1)). In general, the results of this study agreed well with other published results in peer-reviewed journals, except that the total PAs in honey and specific tea infusion in this study were comparatively lower.

  18. Anion adsorption induced surface reconstructions

    NASA Astrophysics Data System (ADS)

    Tang, Lei

    2005-11-01

    Surface stress plays an important role in the behavior of solid surfaces. Potential-controlled anion adsorption in electrolytes alters the surface stress of the electrode and results in morphology changes to the surfaces. With a combination of potential-induced surface stress measurement and in situ electrochemical scanning tunneling microscopy (STM), it is demonstrated that anion adsorption induces changes in structure of thin films and modifies the growth morphology and stress evolution in epitaxially grown films. Surface structural transitions in the heteroepitaxial system consisting of one to two gold monolayers on platinum substrates were observed. By increasing the potential, structural transitions, from (1 x 1), to a striped phase, to a hexagonal structure, occurred in the gold bilayer. This hexagonal structure was related to the formation of an ordered sulfate adlayer with a ( 3x7 ) structure. Such transitions were repeatable by cycling the potential. Furthermore, the transitions between various dislocation structures were affected by anion adsorption. The surface composition of the gold bilayer on Pt was measured by underpotential deposition of copper. By subtracting the contribution of a pure Pt surface from the gold bi-layer on Pt, a stress change of -2.4 N/m was observed, which agrees with the stress change of -2.46 N/m predicted to accompany formation of 1.5 MLs of coherent Au on Pt(111) from epitaxy theory. The Cu monolayer deposited on Au(111) from an acid sulfate electrolyte was found to be pseudomorphic while the Cu monolayer formed on Au(111) in vacuum was incoherent. The stress-thickness change associated with the coherent monolayer of copper on Au(111) in electrolyte was -0.6 N/m, while conventional epitaxy theories predict a value of +7.76 N/m. STM results elucidated the sulfate adsorption on the copper monolayer caused an expansion of the layer as evidenced by a Moire Structure. For the Cu monolayer on Au(111), the sulfate-induced expansion

  19. Leading-edge forensic DNA analyses and the necessity of including crime scene investigators, police officers and technicians in a DNA elimination database.

    PubMed

    Lapointe, Martine; Rogic, Anita; Bourgoin, Sarah; Jolicoeur, Christine; Séguin, Diane

    2015-11-01

    In recent years, sophisticated technology has significantly increased the sensitivity and analytical power of genetic analyses so that very little starting material may now produce viable genetic profiles. This sensitivity however, has also increased the risk of detecting unknown genetic profiles assumed to be that of the perpetrator, yet originate from extraneous sources such as from crime scene workers. These contaminants may mislead investigations, keeping criminal cases active and unresolved for long spans of time. Voluntary submission of DNA samples from crime scene workers is fairly low, therefore we have created a promotional method for our staff elimination database that has resulted in a significant increase in voluntary samples since 2011. Our database enforces privacy safeguards and allows for optional anonymity to all staff members. We also offer information sessions at various police precincts to advise crime scene workers of the importance and success of our staff elimination database. This study, a pioneer in its field, has obtained 327 voluntary submissions from crime scene workers to date, of which 46 individual profiles (14%) have been matched to 58 criminal cases. By implementing our methods and respect for individual privacy, forensic laboratories everywhere may see similar growth and success in explaining unidentified genetic profiles in stagnate criminal cases.

  20. Simultaneous separation and detection of anions and thiophilic cations using capillary-size anion exchange chromatography with suppressed conductivity detection.

    PubMed

    Sötz, Veronika Anna; Kochmann, Sven

    2015-05-01

    In this fundamental study, the simultaneous separation and detection of anions and thiophilic cations in anion exchange chromatography with suppressed conductivity detection is investigated. Mercury(II) and cadmium(II) served as model analytes. Separation and detection was performed by introducing 2-mercaptoethanesulfonate, which forms complexes with both mercury and cadmium with a strong metal-sulfur bond, into the KOH eluent. Additional to the separation on the column, these complexes were able to pass the suppressor. Subsequently, they could be detected as negative peaks. A simple model for the separation mechanism was developed based on these results. Furthermore, the effect of the eluent concentration on the retention factors of both cation complexes and standard anions was examined and quantified. It revealed that the concentration of 2-mercaptoethanesulfonate has more influence on the cations than the KOH concentration. Also, 2.0 mM of 2-mercaptoethanesulfonate had about the same effect on the anion separation as 60 mM KOH. Finally, selectivity and detection limits were investigated. The detection limits were 4.9 μM for mercury and 2.2 μM for cadmium.

  1. Investigation of three-dimensional flow field in a turbine including rotor/stator interaction. II - Three-dimensional flow field at the exit of the nozzle

    NASA Technical Reports Server (NTRS)

    Zaccaria, M.; Lakshminarayana, B.

    1992-01-01

    The nozzle exit flowfield was measured at two axial locations with a miniature five-hole probe. Measurements were taken from hub-to-tip, blade-to-blade at 21 radial locations and at two axial locations downstream of the nozzle trailing edge to resolve the flowfield accurately including the nozzle wake, secondary flow region, horseshoe vortex and losses. All three components of the velocity, stagnation pressure, static pressure, and pitch and yaw angles have been resolved very accurately. The wake data seems to indicate that the decay of the wake is faster than the wake of an isolated nozzle row. The cause of this is attributed to the presence of the rotor downstream. A distinct vortex core has been observed near the tip. The indications are that the horseshoe vortex and the passage vortex have merged to produce a single loss core region. Roughly a third of the blade height passage near the tip and a third of the blade height near the hub is dominated by secondary flow, passage vortex and the horseshoe vortex phenomena. Only the middle third of the nozzle behaves as per design. These and other data are presented, interpreted and synthesized to understand the nozzle flowfield.

  2. Investigation of three-dimensional flow field in a turbine including rotor/stator interaction. II - Three-dimensional flow field at the exit of the nozzle

    NASA Technical Reports Server (NTRS)

    Zaccaria, M.; Lakshminarayana, B.

    1992-01-01

    The nozzle exit flowfield was measured at two axial locations with a miniature five-hole probe. Measurements were taken from hub-to-tip, blade-to-blade at 21 radial locations and at two axial locations downstream of the nozzle trailing edge to resolve the flowfield accurately including the nozzle wake, secondary flow region, horseshoe vortex and losses. All three components of the velocity, stagnation pressure, static pressure, and pitch and yaw angles have been resolved very accurately. The wake data seems to indicate that the decay of the wake is faster than the wake of an isolated nozzle row. The cause of this is attributed to the presence of the rotor downstream. A distinct vortex core has been observed near the tip. The indications are that the horseshoe vortex and the passage vortex have merged to produce a single loss core region. Roughly a third of the blade height passage near the tip and a third of the blade height near the hub is dominated by secondary flow, passage vortex and the horseshoe vortex phenomena. Only the middle third of the nozzle behaves as per design. These and other data are presented, interpreted and synthesized to understand the nozzle flowfield.

  3. Ultra-small and anionic starch nanospheres: formation and vitro thrombolytic behavior study.

    PubMed

    Huang, Yinjuan; Ding, Shenglong; Liu, Mingzhu; Gao, Chunmei; Yang, Jinlong; Zhang, Xinjie; Ding, Bin

    2013-07-25

    This paper is considered as the first report on the investigation of nattokinase (NK) release from anionic starch nanospheres. The ultra-small and anionic starch nanospheres were prepared by the method of reverse micro-emulsion crosslinking in this work. Starch nanospheres were characterized through Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). Effects of preparation conditions on particle size were studied. The cytotoxicity, biodegradable and vitro thrombolytic behaviors of nattokinase (NK) loaded anionic starch nanospheres were also studied. The results showed that the anionic starch nanospheres are non-toxic, biocompatible and biodegradable. Moreover, the anionic starch nanospheres can protect NK from fast biodegradation hence prolongs the circulation in vivo and can reduce the risk of acute hemorrhage complication by decreasing the thrombolysis rate.

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

    PubMed

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

    2016-03-04

    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.

  5. Anion Photoelectron Spectroscopy of the Homogenous 2-Hydroxypyridine Dimer Electron Induced Proton Transfer System

    NASA Astrophysics Data System (ADS)

    Vlk, Alexandra; Stokes, Sarah; Wang, Yi; Hicks, Zachary; Zhang, Xinxing; Blando, Nicolas; Frock, Andrew; Marquez, Sara; Bowen, Kit; Bowen Lab JHU Team

    Anion photoelectron spectroscopic (PES) and density functional theory (DFT) studies on the dimer anion of (2-hydroxypyridine)2-are reported. The experimentally measured vertical detachment energy (VDE) of 1.21eV compares well with the theoretically predicted values. The 2-hydroxypyridine anionic dimer system was investigated because of its resemblance to the nitrogenous heterocyclic pyrimidine nucleobases. Experimental and theoretical results show electron induced proton transfer (EIPT) in both the lactim and lactam homogeneous dimers. Upon electron attachment, the anion can serve as the intermediate between the two neutral dimers. A possible double proton transfer process can occur from the neutral (2-hydroxypyridine)2 to (2-pyridone)2 through the dimer anion. This potentially suggests an electron catalyzed double proton transfer mechanism of tautomerization. Research supported by the NSF Grant No. CHE-1360692.

  6. Do anionic titanium dioxide nano-clusters reach bulk band gap? A density functional theory study.

    PubMed

    Qu, Zheng-Wang; Zhu, Hui

    2010-07-30

    The electronic properties of both neutral and anionic (TiO(2))(n) (n = 1-10) clusters are investigated by extensive density functional theory calculations. The predicted electron detachment energies and excitation gaps of anionic clusters agree well with the original experimental anion photoelectron spectra (APES). It is shown that the old way to analyze APES tends to overestimate vertical excitation gaps (VGA) of large anionic clusters, due to the nature of multiple electronic origins for the higher APES bands. Moreover, the VGA of anionic TiO(2) clusters are evidently smaller than those of neutral clusters, which may also be the case for other metal oxide clusters with high electron affinity.

  7. THE EFFECTS OF MOLECULAR ANIONS ON THE CHEMISTRY OF DARK CLOUDS

    SciTech Connect

    Walsh, Catherine; Millar, T. J.; Harada, Nanase; Herbst, Eric

    2009-07-20

    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 Taurus molecular cloud 1 (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 C{sub n}H, C{sub n}H{sub 2}, and HC{sub n}N. The use of carbon-rich elemental abundances in models of TMC-1 (CP) with anion chemistry worsens the agreement with observations compared with model results obtained in the absence of anions.

  8. 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

    NASA Astrophysics Data System (ADS)

    Sun, Gang; Wang, Wenfeng; Wu, Jilan

    2007-06-01

    The reaction of solvated electrons with baicalin in N 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 1.3×10 4 M -1 cm -1. The rate constant for the build-up of the baicalin radical anion is 1.3(±0.4)×10 10 M -1 s -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)×10 3 s -1 and a second-order reaction with rate constant 1.3(±0.2)×10 9 M -1 s -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.

  9. A new anion-exchange/hydrophobic monolith as stationary phase for nano liquid chromatography of small organic molecules and inorganic anions.

    PubMed

    Aydoğan, Cemil

    2015-05-01

    In this study, an anion-exchange/hydrophobic polymethacrylate-based stationary phase was prepared for nano-liquid chromatography of small organic molecules and inorganic anions. The stationary phase was synthesized by in situ polymerization of 3-chloro-2-hydroxypropylmethacrylate and ethylene dimethacrylate inside silanized 100 μm i.d. fused silica capillary. The porogen mixture consisted of toluene and dodecanol. The pore size distrubution profiles of the resulting monolith were determined by mercury intrusion porosimetry and the morphology of the prepared monolith was investigated by scanning electron microscope. Good permeability, stability and column efficiency were observed on the monolithic column with nano flow. The produced monolithic column, which contains reactive chloro groups, was then modified by reaction with N,N-dimethyl-N-dodecylamine to obtain an anion-exchange/hydrophobic monolithic stationary phase. The functionalized monolith contained ionizable amine groups and hydrophobic groups that are useful of anion-exchange/hydrophobic mixed-mode chromatography. The final monolithic column performance with respect to anion-exchange and hydrophobic interactions was assesed by the separation of alkylbenzene derivatives, phenolic compounds and inorganic anions, respectively. Theoretical plate numbers up to 23,000 plates/m were successfully achieved in the separation of inorganic anions.

  10. Surface-enhanced Raman scattering of perchlorate on cationic-modified silver nanofilms - Effect of inorganic anions

    NASA Astrophysics Data System (ADS)

    Hao, Jumin; Han, Mei-Juan; Meng, Xiaoguang; Weimer, Wayne; Wang, Qingwu K.

    2015-02-01

    Surface-enhanced Raman scattering (SERS) has emerged as one of the most sensitive spectroscopic analysis methods for the detection of environmental contaminants in water, including perchlorate (ClO4-). However, as with other commonly used analytical techniques, analysis of realistic environmental samples by SERS presents a challenge due to complex chemical components coexisting in the samples. In this work, we investigated the influence of inorganic anions (particularly oxyanions) on SERS spectra of ClO4- using a cationic thiol modified silver nanofilm substrate (Cys-Ag/rCu). The results show that the anions present in the samples did not shift the ClO4- characteristic band positions, but did decrease signal intensities due to their competitive binding with the -NH3+ groups of cationic thiol molecules immobilized on the substrates. The pH changes caused by both the dissociation of H2PO4- and the hydrolysis of HCO3- may also play a non-negligible role. The selectivity of the Cys-Ag/rCu substrate towards these anions was determined to be in the following order: ClO4- > SO42- > HCO3-, NO3- > Cl- > H2PO4-, indicating preferential adsorption of ClO4- ions. In the solutions with multiple anions present, the ClO4- SERS spectra were affected simultaneously by all the coexisting anions. Calibration curves with very good linear relationships were successfully obtained, demonstrating the great potential of quantitative detection of aqueous ClO4- in the matrix.

  11. Nexal membrane permeability to anions

    PubMed Central

    1978-01-01

    The permeability of the septa of the earthworm in the median axon has been calculated for the anions fluorescein and its halogen derivatives. The values ranged from 5.4 X 10(-5) to 4 X 10(-6) cm/s. Previously, the septa had been shown to contain nexuses. By using freeze-fracture material, the surface area of nexus on the septal membranes was determined to be 4.5%, very similar to the percentage of nexus in the intercalated disk of mammalian myocardium. Plasma membrane permeability to these dyes was also calculated and shown to be much less than that of the septal membranes. In addition, an estimate of cytoplasmic binding for each dye was made, and most dyes showed little or no binding with the exception of aminofluorescein. PMID:702107

  12. Lumbar spine and pelvic posture between standing and sitting: a radiologic investigation including reliability and repeatability of the lumbar lordosis measure.

    PubMed

    De Carvalho, Diana E; Soave, David; Ross, Kim; Callaghan, Jack P

    2010-01-01

    Sitting has been identified as a cause of mechanical low back pain. The purpose of this study was to use plain film x-rays to measure lumbar spine and pelvic posture differences between standing and sitting. Eight male subjects were radiographed standing and sitting in an automobile seat. Measures of lumbar lordosis, intervertebral disk angles, lumbosacral angle, lumbosacral lordosis, and sacral tilt were completed. One-way analysis of variance (alpha = .05) was conducted on the variables stated above. A Bland-Altman analysis was conducted to assess agreement and repeatability of the lumbar lordosis angle using 2 raters. Lumbar lordosis values in standing (average, 63 degrees +/- 15 degrees ) and sacral inclination (average, 43 degrees +/- 10 degrees ) decreased by 43 degrees and 44 degrees , respectively, in sitting. Intervertebral joint angles in sitting underwent substantial flexion (L1/L2-5 degrees [+/-3 degrees ], L2/L3-7 degrees [+/-3 degrees ], L3/L4-8 degrees [+/-3 degrees ], L4/L5-13 degrees [+/-3 degrees ], and L5/S1-4 degrees [+/-10 degrees ]). Measures of lumbar lordosis; intervertebral disk angles between L2/L3, L3/L4, and L4/L5; lumbosacral lordosis; lumbosacral angle; and sacral tilt were significantly decreased between standing and sitting (P < .001). Intervertebral disk angle between L5/S1 was not significantly different. Analysis using the Bland-Altman technique found good agreement and stable repeatability of measures with no statistical significant differences between or within raters (R1, P = .8474; R2, P = .4402; and R-R2, P = .8691). The significant differences in lumbar and pelvic measures from standing to sitting further emphasize the range of motion experienced at vertebral levels in sitting. Based on the results of this study, interventions to return motion segments to a less flexed posture should be investigated because they may play a role in preventing injury and low back pain. Copyright 2010 National University of Health Sciences

  13. Anionic fructose-related conformational and positional isomers assigned through PES experiments and DFT calculations.

    PubMed

    Zeng, Zhen; Bernstein, Elliot R

    2017-08-30

    Gas phase, isolated fructose anionic species, fructose(-), (fructose-H)(-), (fructose-OH)(-), and (fructose-H2O)(-), are investigated employing anionic photoelectron spectroscopy (PES) combined with density functional theory (DFT) calculations. The PES vertical detachment energies (VDEs) for these anions are determined and, based on these experimental values, their calculated anionic structures are assigned. Generation of these four species through the matrix assisted laser desorption ionization (MALDI) process is sample desorption substrate dependent. The parent anion fructose(-) exists as a single, dominant open chain structure in the gas phase, with substrate dependent specific conformational isomers. (Fructose-H)(-) and (fructose-OH)(-) are mainly produced from the laser ablation process rather than from fragmentation reaction pathways associated with the parent anion species. Both conformational and positional isomers are identified in the gas phase for these latter anions. (Fructose-H2O)(-) has two types of positional isomers, both of which contribute to two different components of the observed PES feature. The fixed positions for losing an OH group and an H atom, in addition to thermodynamic calculations, provide reaction pathways for generating a dehydration product (open chain structures) from the parent anion (open chain and furanose structures), further demonstrating the active nature of fructose upon capturing an extra electron.

  14. Superoxide anion-induced pain and inflammation depends on TNFα/TNFR1 signaling in mice.

    PubMed

    Yamacita-Borin, Fabiane Y; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Fattori, Victor; Alves-Filho, Jose C; Cunha, Fernando Q; Cunha, Thiago M; Casagrande, Rubia; Verri, Waldiceu A

    2015-09-25

    Inhibition of tumor necrosis factor-alpha (TNFα) and superoxide anion production reduces inflammation and pain. The present study investigated whether superoxide anion-induced pain depends on TNFα signaling and the role of superoxide anion in TNFα-induced hyperalgesia to clarify the interrelation between these two mediators in the context of pain. Intraplantar injection of a superoxide anion donor (potassium superoxide) induced mechanical hyperalgesia (0.5-5h after injection), neutrophil recruitment (myeloperoxidase activity), and overt pain-like behaviors (paw flinching, paw licking, and abdominal writhings) in wild-type mice. Tumor necrosis factor receptor 1 deficiency (TNFR1-/-) and treatment of wild-type mice with etanercept (a soluble TNFR2 receptor that inhibits TNFα actions) inhibited superoxide anion-induced pain-like behaviors. TNFR1(-/-) mice were also protected from superoxide anion donor-induced oxidative stress, suggesting the role of this pathway in the maintenance of oxidative stress. Finally, we demonstrated that Apocynin (an NADPH oxidase inhibitor) or Tempol (a superoxide dismutase mimetic) treatment inhibited TNFα-induced paw mechanical hyperalgesia and neutrophil recruitment (myeloperoxidase activity). These results demonstrate that TNFα/TNFR1 signaling is important in superoxide anion-triggered pain and that TNFα/TNFR1 signaling amplifies the oxidative stress triggered by superoxide anion, which contributes to sustaining pain and inflammation.

  15. Tripodal Receptors for Cation and Anion Sensors

    PubMed Central

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

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selective recognition and sensing of cations and anions. Examples on the relationship between structure and selectivity towards cations and anions are described. Furthermore, their applications as potentiometric ion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  16. Regeneration of strong-base anion-exchange resins by sequential chemical displacement

    DOEpatents

    Brown, Gilbert M.; Gu, Baohua; Moyer, Bruce A.; Bonnesen, Peter V.

    2002-01-01

    A method for regenerating strong-base anion exchange resins utilizing a sequential chemical displacement technique with new regenerant formulation. The new first regenerant solution is composed of a mixture of ferric chloride, a water-miscible organic solvent, hydrochloric acid, and water in which tetrachloroferrate anion is formed and used to displace the target anions on the resin. The second regenerant is composed of a dilute hydrochloric acid and is used to decompose tetrachloroferrate and elute ferric ions, thereby regenerating the resin. Alternative chemical displacement methods include: (1) displacement of target anions with fluoroborate followed by nitrate or salicylate and (2) displacement of target anions with salicylate followed by dilute hydrochloric acid. The methodology offers an improved regeneration efficiency, recovery, and waste minimization over the conventional displacement technique using sodium chloride (or a brine) or alkali metal hydroxide.

  17. Physicochemical treatments of anionic surfactants wastewater: Effect on aerobic biodegradability.

    PubMed

    Aloui, Fathi; Kchaou, Sonia; Sayadi, Sami

    2009-05-15

    The effect of different physicochemical treatments on the aerobic biodegradability of an industrial wastewater resulting from a cosmetic industry has been investigated. This industrial wastewater contains 11423 and 3148mgL(-1) of chemical oxygen demand (COD) and anionic surfactants, respectively. The concentration of COD and anionic surfactants were followed throughout the diverse physicochemical treatments and biodegradation experiments. Different pretreatments of this industrial wastewater using chemical flocculation process with lime and aluminium sulphate (alum), and also advanced oxidation process (electro-coagulation (Fe and Al) and electro-Fenton) led to important COD and anionic surfactants removals. The best results were obtained using electro-Fenton process, exceeding 98 and 80% of anionic surfactants and COD removals, respectively. The biological treatment by an isolated strain Citrobacter braakii of the surfactant wastewater, as well as the pretreated wastewater by the various physicochemical processes used in this study showed that the best results were obtained with electro-Fenton pretreated wastewater. The characterization of the treated surfactant wastewater by the integrated process (electro-coagulation or electro-Fenton)-biological showed that it respects Tunisian discharge standards.

  18. Relationship Between Equilibrium Forms of Lysozyme Crystals and Precipitant Anions

    NASA Technical Reports Server (NTRS)

    Nadarajah, Arunan

    1996-01-01

    Molecular forces, such as electrostatic, hydrophobic, van der Waals and steric forces, are known to be important in determining protein interactions. These forces are affected by the solution conditions and changing the pH, temperature or the ionic strength of the solution can sharply affect protein interactions. Several investigations of protein crystallization have shown that this process is also strongly dependent on solution conditions. As the ionic strength of the solution is increased, the initially soluble protein may either crystallize or form an amorphous precipitate at high ionic strengths. Studies done on the model protein hen egg white lysozyme have shown that different crystal forms can be easily and reproducibly obtained, depending primarily on the anion used to desolubilize the protein. In this study we employ pyranine to probe the effect of various anions on the water structure. Additionally, lysozyme crystallization was carried out at these conditions and the crystal form was determined by X-ray crystallography. The goal of the study was to understand the physico-chemical basis for the effect of changing the anion concentration on the equilibrium form of lysozyme crystals. It will also verify the hypothesis that the anions, by altering the bulk water structure in the crystallizing solutions, alter the surface energy of the between the crystal faces and the solution and, consequently, the equilibrium form of the crystals.

  19. Efficiency of superoxide anions in the inactivation of selected dehydrogenases

    NASA Astrophysics Data System (ADS)

    Rodacka, Aleksandra; Serafin, Eligiusz; Puchala, Mieczyslaw

    2010-09-01

    The most ubiquitous of the primary reactive oxygen species, formed in all aerobes, is the superoxide free radical. It is believed that the superoxide anion radical shows low reactivity and in oxidative stress it is regarded mainly as an initiator of more reactive species such as rad OH and ONOO -. In this paper, the effectiveness of inactivation of selected enzymes by radiation-generated superoxide radicals in comparison with the effectiveness of the other products of water radiolysis is examined. We investigate three enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH). We show that the direct contribution of the superoxide anion radical to GAPDH and ADH inactivation is significant. The effectiveness of the superoxide anion in the inactivation of GAPDH and ADG was only 2.4 and 2.8 times smaller, respectively, in comparison with hydroxyl radical. LDH was practically not inactivated by the superoxide anion. Despite the fact that the studied dehydrogenases belong to the same class of enzymes (oxidoreductases), all have a similar molecular weight and are tetramers, their susceptibility to free-radical damage varies. The differences in the radiosensitivity of the enzymes are not determined by the basic structural parameters analyzed. A significant role in inactivation susceptibility is played by the type of amino acid residues and their localization within enzyme molecules.

  20. Anion Bohr effect of human hemoglobin.

    PubMed

    Bucci, E; Fronticelli, C

    1985-01-15

    The pH dependence of oxygen affinity of hemoglobin (Bohr effect) is due to ligand-linked pK shifts of ionizable groups. Attempt to identify these groups has produced controversial data and interpretations. In a further attempt to clarify the situation, we noticed that hemoglobin alkylated in its liganded form lost the Bohr effect while hemoglobin alkylated in its unliganded form showed the presence of a practically unmodified Bohr effect. In spite of this difference, analyses of the extent of alkylation of the two compounds failed to identify the presence of specific preferential alkylations. In particular, the alpha 1 valines and beta 146 histidines appeared to be alkylated to the same extent in the two proteins. Focusing our attention on the effect of the anions on the functional properties of hemoglobin, we measured the Bohr effect of untreated hemoglobin in buffers made with HEPES [N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid], MES [2-(N-morpholino)ethanesulfonic acid], and MOPS [3-(N-morpholino)propanesulfonic acid], which being zwitterions do not need addition of chlorides or other anions for reaching the desired pH. The shape acquired by the Bohr effect curves, either as pH dependence of oxygen affinity or as pH dependence of protons exchanged with the solution, was irreconcilable with that of the Bohr effect curves in usual buffers. This indicated the relevance of solvent components in determining the functional properties of hemoglobin. A new thermodynamic model is proposed for the Bohr effect that includes the interaction of hemoglobin with solvent components. The classic proton Bohr effect is a special case of the new theory.

  1. Anion-π Catalysis on Fullerenes.

    PubMed

    López-Andarias, Javier; Frontera, Antonio; Matile, Stefan

    2017-09-13

    Anion-π interactions on fullerenes are about as poorly explored as the use of fullerenes in catalysis. However, strong exchange-correlation contributions and the localized π holes on their surface promise unique selectivities. To elaborate on this promise, tertiary amines are attached nearby. Dependent on their positioning, the resulting stabilization of anionic transition states on fullerenes is shown to accelerate disfavored enolate addition and exo Diels-Alder reactions enantioselectively. The found selectivities are consistent with computational simulations, particularly concerning the discrimination of differently planarized and charge-delocalized enolate tautomers by anion-π interactions. Enolate-π interactions on fullerenes are much shorter than standard π-π interactions and anion-π interactions on planar surfaces, and alternative cation-π interactions are not observed. These findings open new perspectives with regard to anion-π interactions in general and the use of carbon allotropes in catalysis.

  2. Creating molecular macrocycles for anion recognition

    PubMed Central

    2016-01-01

    Summary The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures. PMID:27340452

  3. Asymmetric Anion-π Catalysis on Perylenediimides.

    PubMed

    Wang, Chao; Miros, François N; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2016-11-07

    Anion-π catalysis, that is the stabilization of anionic transition states on π-acidic aromatic surfaces, has so far been developed with naphthalenediimides (NDIs). This report introduces perylenediimides (PDIs) to anion-π catalysis. The quadrupole moment of PDIs (+23.2 B) is found to exceed that of NDIs and reach new records with acceptors in the core (+70.9 B), and their larger surface provides space to better accommodate chemical transformations. Unlike NDIs, the activity of PDI catalysts for enolate and enamine addition is determined by the twist of their π surface rather than their reducibility. These results, further strengthened by nitrate inhibition and circular dichroism spectroscopy, support an understanding of anion-π interactions centered around quadrupole moments, i.e., electrostatic contributions, rather than redox potentials and charge transfer. The large PDI surfaces provide access to the highest enantioselectivities observed so far in anion-π catalysis (96 % ee).

  4. Closing the gap on unmeasured anions

    PubMed Central

    Kellum, John A

    2003-01-01

    Many critically ill and injured patients, especially those with metabolic acidosis, have abnormally high levels of unmeasured anions in their blood. At the same time, such patients are prone to hypoalbuminemia, which makes the traditional anion gap calculation inaccurate. Thus, little is known about the epidemiology and clinical consequences of an excess in unmeasured anions in the blood. Indeed, even the etiology of these "missing ions" is often unclear. Unfortunately, more precise means of quantifying unmeasured anions, such as the strong ion gap (SIG), are cumbersome to use clinically. However, a simple means of correcting the anion gap can be used to estimate SIG and may provide additional insight into this common clinical problem. PMID:12793870

  5. Covalent Polymers Containing Discrete Heterocyclic Anion Receptors

    PubMed Central

    Rambo, Brett M.; Silver, Eric S.; Bielawski, Christopher W.; Sessler, Jonathan L.

    2010-01-01

    This chapter covers recent advances in the development of polymeric materials containing discrete heterocyclic anion receptors, and focuses on advances in anion binding and chemosensor chemistry. The development of polymers specific for anionic species is a relatively new and flourishing area of materials chemistry. The incorporation of heterocyclic receptors capable of complexing anions through non-covalent interactions (e.g., hydrogen bonding and electrostatic interactions) provides a route to not only sensitive but also selective polymer materials. Furthermore, these systems have been utilized in the development of polymers capable of extracting anionic species from aqueous environments. These latter materials may lead to advances in water purification and treatment of diseases resulting from surplus ions. PMID:20871791

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

    PubMed

    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.

  7. 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

    NASA Astrophysics Data System (ADS)

    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.

  8. 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.

    PubMed

    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 d(4)-pregnenolone, are also discussed.

  9. Anion stripping as a general method to create cationic porous framework with mobile anions.

    PubMed

    Mao, Chengyu; Kudla, Ryan A; Zuo, Fan; Zhao, Xiang; Mueller, Leonard J; Bu, Xianhui; Feng, Pingyun

    2014-05-28

    Metal-organic frameworks (MOFs) with cationic frameworks and mobile anions have many applications from sensing, anion exchange and separation, to fast ion conductivity. Despite recent progress, the vast majority of MOFs have neutral frameworks. A common mechanism for the formation of neutral frameworks is the attachment of anionic species such as F(-) or OH(-) to the framework metal sites, neutralizing an otherwise cationic scaffolding. Here, we report a general method capable of converting such neutral frameworks directly into cationic ones with concurrent generation of mobile anions. Our method is based on the differential affinity between distinct metal ions with framework anionic species. Specifically, Al(3+) is used to strip F(-) anions away from framework Cr(3+) sites, leading to cationic frameworks with mobile Cl(-) anions. The subsequent anion exchange with OH(-) further leads to a porous network with mobile OH(-) anions. New materials prepared by anion stripping can undergo ion exchange with anionic organic dyes and also exhibit much improved ionic conductivity compared to the original unmodified MOFs.

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Anion-π Catalysis of Diels-Alder Reactions.

    PubMed

    Liu, Le; Cotelle, Yoann; Bornhof, Anna-Bea; Besnard, Céline; Sakai, Naomi; Matile, Stefan

    2017-09-08

    Among concerted cycloadditions, the Diels-Alder reaction is the grand old classic, which is usually achieved with acid catalysis. In this report, hydroxypyrones, oxa-, and thiazolones are explored because they provide access to anionic dienes. Their [4+2] cycloaddition with cyclic and acyclic dienophiles, such as maleimides and fumarates, affords bicyclic products with four new stereogenic centers. Bifunctional anion-π catalysts composed of amine bases next to the π surface of naphthalenediimides (NDIs) are shown to selectively stabilize the "open", fully accessible anionic exo transition state on the π-acidic aromatic surface. Our results also include reactivities that are hard to access with conventional organocatalysts, such as the exo-specific and highly enantioselective Diels-Alder reaction of thiazolones and maleimides with complete suppression of the otherwise dominant Michael addition. With increasing π acidity of the anion-π catalysts, the rates, chemo-, diastereo-, and enantioselectivities increase consistently. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. X-ray photoelectron spectroscopy of trihalide ionic liquids: Comparison to halide-based analogues, anion basicity and beam damage

    NASA Astrophysics Data System (ADS)

    Men, Shuang; Lovelock, Kevin R. J.; Licence, Peter

    2017-07-01

    X-ray photoelectron spectroscopy is used to investigate two 1-octyl-3-methylimidazolium trihalide ionic liquids, with anions including triiodide and iododibromide. The electronic environment of each element present in ionic liquids studied herein is analysed and compared to their halide-based analogous. The anion basicity is compared based upon the measured N 1s binding energy. The iododibromide ionic liquid is studied as a representative sample to illustrate the beam damage effect. Due to the beam damage, there is a new formed bromine component observed. This effect is calculated and demonstrated for all elements present within the ionic liquid. It suggests that the beam induced decomposition caused a stoichiometric loss of bromine atom and iodine atom.

  13. Fluoride removal mechanism of bayerite/boehmite nanocomposites: roles of the surface hydroxyl groups and the nitrate anions.

    PubMed

    Jia, Yong; Zhu, Bai-Sheng; Jin, Zhen; Sun, Bai; Luo, Tao; Yu, Xin-Yao; Kong, Ling-Tao; Liu, Jin-Huai

    2015-02-15

    Three-dimensional feather like bayerite/boehmite nanocomposites were synthesized by a facile one-pot hydrothermal method. The obtained nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The removal properties toward fluoride were investigated, including adsorption kinetics, adsorption isotherm, and influences of pH and coexisting anions. The maximal adsorption capacity was 56.80 mg g(-1) at pH 7.0, which is favorable compared to those reported in the literature using other adsorbents. The coexisting of sulfate and bicarbonate inhibited the fluoride removal especially at high concentrations. Furthermore, the removal mechanism was revealed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results suggest that both of the surface hydroxyl groups and the nitrate anions were participated in the ion-exchange process.

  14. Olfactory mucosa-expressed organic anion transporter, Oat6, manifests high affinity interactions with odorant organic anions

    PubMed Central

    Kaler, Gregory; Truong, David M.; Sweeney, Derina E.; Logan, Darren W.; Nagle, Megha; Eraly, Satish A.; Nigam, Sanjay K.

    2007-01-01

    We have characterized the expression of organic anion transporter 6, Oat6 (slc22a20), in olfactory mucosa, as well as its interaction with several odorant organic anions. In situ hybridization reveals diffuse Oat6 expression throughout olfactory epithelium, yet olfactory neurons laser-capture microdissected from either the main olfactory epithelium (MOE) or the vomeronasal organ (VNO) did not express Oat6 mRNA. These data suggest that Oat6 is expressed in non-neuronal cells of olfactory tissue, such as epithelial and/or other supporting cells. We next investigated interaction of Oat6 with several small organic anions that have previously been identified as odortype components in mouse urine. We find that each of these compounds, propionate, 2- and 3-methylbutyrate, benzoate, heptanoate and 2-ethylhexanoate, inhibits Oat6-mediated uptake of a labeled tracer, estrone sulfate, consistent with their being Oat6 substrates. Previously, we noted defects in the renal elimination of odortype and odortype-like molecules in Oat1 knockout mice. The finding that such molecules interact with Oat6 raises the possibility that odorants secreted into the urine through one OAT-mediated mechanism are transported through the olfactory mucosa through another OAT-mediated mechanism. Oat6 might play a direct or indirect role in olfaction, such as modulation of the availability of odorant organic anions at the mucosal surface for presentation to olfactory neurons or facilitation of delivery to a distal site of chemosensation, among other possibilities that we discuss. PMID:17094945

  15. Anion Exchange on Cationic Surfactant Micelles, and a Speciation Model for Estimating Anion Removal on Micelles during Ultrafiltration of Water.

    PubMed

    Chen, Ming; Jafvert, Chad T

    2017-07-05

    Surfactant micelles combined with ultrafiltration can partially, or sometimes nearly completely, separate various ionic and nonionic pollutants from water. To this end, the selectivity of aqueous micelles composed of either cetyltrimethylammonium (CTA(+)) bromide or cetylpyridinium (CP(+)) chloride toward many environmentally relevant anions (IO3(-), F(-), Cl(-), HCO3(-), NO2(-), Br(-), NO3(-), H2PO4(-), HPO4(2-), SO4(2-), and CrO4(2-)) was investigated. Selectivity coefficients of CTA(+) micelles (with respect to Br(-)) and CP(+) micelle (with respect to Cl(-)) for these anions were evaluated using a simple thermodynamic ion exchange model. The sequence of anion affinity for the CTA(+) micelles and for the CP(+) micelles were the same, with decreasing affinity occurring in the order of: CrO4(2-) > SO4(2-) > HPO4(2-) > NO3(-) > Br(-) > NO2(-) > Cl(-) > HCO3(-) > H2PO4(-) ≈ F(-). From the associated component mass balance and ion exchange (i.e., mass action) equations, an overall speciation model was developed to predict the distribution of all anions between the aqueous and micellar pseudophase for complex ionic mixtures. Experimental results of both artificial and real surface waters were in good agreement to model predictions. Further, the results indicated that micelles combined with ultrafiltration may be a potential technology for nutrient and other pollutant removal from natural or effluent waters.

  16. Electron Impact Ionization/Dissociation of Molecules: Production of Energetic Radical Ions and Anions

    NASA Astrophysics Data System (ADS)

    Feil, S.; Sulzer, P.; Mauracher, A.; Beikircher, M.; Wendt, N.; Aleem, A.; Denifl, S.; Zappa, F.; Matt-Leubner, S.; Bacher, A.; Matejcik, S.; Probst, M.; Scheier, P.; Märk, T. D.

    2007-10-01

    In order to provide quantitative information on electron collision processes involving various plasma constituents (in particular hydrocarbons) and to elucidate the properties of cations and anions produced we have carried out the past years a series of studies with a variety of techniques in our laboratory in Innsbruck. In the present review we will present some recent results on electron impact ionization and attachment in order to illustrate recent progress in this field in particular concerning the production of energetic fragment cations for hydrocarbons and differences in the attachment of isomers for nitro-organics. Using a Nier type electron impact ion source in combination with a double focusing two sector field mass spectrometer, partial cross sections for electron impact ionization of acetylene, propene and other hydrocarbons have been measured for electron energies up to 1000 eV. Discrimination factors for ions have been determined using the deflection field method in combination with a three-dimensional ion trajectory simulation of ions produced in the ion source. Analysis of the ion yield curves obtained by scanning the deflectors allows the assignment of ions with the same mass-to-charge ratio to specific production channels on the basis of their different kinetic energy distributions. This analysis also allows to determine, besides kinetic energy distributions of fragment ions, partial cross sections differential in kinetic energy. Moreover charge separation reactions (for instance in case of acetylene the Coulomb explosion of the doubly-charged parent ions C2H2++ into the fragment ions C2H+ and H+) are investigated by means of a number of metastable mass spectrometry methods and the associated mean kinetic energy release is deduced. Free electron attachment to the three different isomers of mono-nitrotoluene molecules in the gas phase is studied using two different crossed electron-molecule beams technique. In contrast to previous studies for a

  17. Supramolecular electron transfer by anion binding.

    PubMed

    Fukuzumi, Shunichi; Ohkubo, Kei; D'Souza, Francis; Sessler, Jonathan L

    2012-10-11

    Anion binding has emerged as an attractive strategy to construct supramolecular electron donor-acceptor complexes. In recent years, the level of sophistication in the design of these systems has advanced to the point where it is possible to create ensembles that mimic key aspects of the photoinduced electron-transfer events operative in the photosynthetic reaction centre. Although anion binding is a reversible process, kinetic studies on anion binding and dissociation processes, as well as photoinduced electron-transfer and back electron-transfer reactions in supramolecular electron donor-acceptor complexes formed by anion binding, have revealed that photoinduced electron transfer and back electron transfer occur at time scales much faster than those associated with anion binding and dissociation. This difference in rates ensures that the linkage between electron donor and acceptor moieties is maintained over the course of most forward and back electron-transfer processes. A particular example of this principle is illustrated by electron-transfer ensembles based on tetrathiafulvalene calix[4]pyrroles (TTF-C4Ps). In these ensembles, the TTF-C4Ps act as donors, transferring electrons to various electron acceptors after anion binding. Competition with non-redox active substrates is also observed. Anion binding to the pyrrole amine groups of an oxoporphyrinogen unit within various supramolecular complexes formed with fullerenes also results in acceleration of the photoinduced electron-transfer process but deceleration of the back electron transfer; again, this is ascribed to favourable structural and electronic changes. Anion binding also plays a role in stabilizing supramolecular complexes between sulphonated tetraphenylporphyrin anions ([MTPPS](4-): M = H(2) and Zn) and a lithium ion encapsulated C(60) (Li(+)@C(60)); the resulting ensemble produces long-lived charge-separated states upon photoexcitation of the porphyrins.

  18. Preparation a new sorbent based on polymeric ionic liquid for stir cake sorptive extraction of organic compounds and inorganic anions.

    PubMed

    Huang, Xiaojia; Wang, Yulei; Hong, Qiuyun; Liu, Yi; Yuan, Dongxing

    2013-11-01

    A new multi-interaction sorbent (MIS) based on polymeric ionic liquid was prepared and used as extractive medium of stir cake sorptive extraction (SCSE). In the presence of dimethyl sulfoxide, an ionic liquid, 1-vinylbenzyl-3-methylimidazolium chloride was used as monomer to copolymerize in situ with divinylbenzene to form the MIS. The influences of the content of monomer and the porogen solvent in the polymerization mixture on the extraction performance were investigated thoroughly. The MIS was characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. Parabens and aromatic amines were used to investigate the extraction performance of MIS-SCSE for apolar and strongly polar analytes, respectively. The extraction parameters for parabens and aromatic amines were optimized. At the same time, simple and sensitive analytical methods for parabens and aromatic amines in real samples were developed by the combination of MIS-SCSE and HPLC/DAD. Some inorganic anions, such as F(-), Br(-), NO3(-), PO4(3-) and SO4(2-), were used to test the extraction performance of MIS-SCSE for anions. Results indicated that mechanism involved in the extraction of MIS is the multi-interaction modes including π-π, hydrophobic, hydrogen-bonding, dipole-dipole and anion-exchange interactions. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Anion photoelectron imaging spectroscopy of glyoxal

    NASA Astrophysics Data System (ADS)

    Xue, Tian; Dixon, Andrew R.; Sanov, Andrei

    2016-09-01

    We report a photoelectron imaging study of the radical-anion of glyoxal. The 532 nm photoelectron spectrum provides the first direct spectroscopic determination of the adiabatic electron affinity of glyoxal, EA = 1.10 ± 0.02 eV. This assignment is supported by a Franck-Condon simulation of the experimental spectrum that successfully reproduces the observed spectral features. The vertical detachment energy of the radical-anion is determined as VDE = 1.30 ± 0.04 eV. The reported EA and VDE values are attributed to the most stable (C2h symmetry) isomers of the neutral and the anion.

  20. Anion inhibitors of the β-carbonic anhydrase from the pathogenic bacterium responsible of tularemia, Francisella tularensis.

    PubMed

    Del Prete, Sonia; Vullo, Daniela; Osman, Sameh M; AlOthman, Zeid; Donald, William A; Winum, Jean-Yves; Supuran, Claudiu T; Capasso, Clemente

    2017-09-01

    A β-class carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium Francisella tularensis (FtuβCA) was cloned and purified, and the anion inhibition profile was investigated. Based on the measured kinetic parameters for the enzyme catalyzed CO2 hydration reaction (kcat of 9.8×10(5)s(-1) and a kcat/KM of 8.9×10(7)M(-1)s(-1)), FtuβCA is a highly effective enzyme. The activity of FtuβCA was not inhibited by a range of anions that do not typically coordinate Zn(II) effectively, including perchlorate, tetrafluoroborate, and hexafluorophosphate. Surprisingly, some anions which generally complex well with many cations, including Zn(II), also did not effectively inhibit FtuβCA, e.g., fluoride, cyanide, azide, nitrite, bisulphite, sulfate, tellurate, perrhenate, perrhuthenate, and peroxydisulfate. However, the most effective inhibitors were in the range of 90-94µM (sulfamide, sulfamic acid, phenylarsonic and phenylboronic acid). N,N-Diethyldithiocarbamate (KI of 0.31mM) was a moderately potent inhibitor. As Francisella tularensis is the causative agent of tularemia, the discovery of compounds that can interfere with the life cycle of this pathogen may result in novel opportunities to fight antibiotic drug resistance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Anion-switchable supramolecular gels for controlling pharmaceutical crystal growth

    NASA Astrophysics Data System (ADS)

    Foster, Jonathan A.; Piepenbrock, Marc-Oliver M.; Lloyd, Gareth O.; Clarke, Nigel; Howard, Judith A. K.; Steed, Jonathan W.

    2010-12-01

    We describe the use of low-molecular-weight supramolecular gels as media for the growth of molecular crystals. Growth of a range of crystals of organic compounds, including pharmaceuticals, was achieved in bis(urea) gels. Low-molecular-weight supramolecular gelators allow access to an unlimited range of solvent systems, in contrast to conventional aqueous gels such as gelatin and agarose. A detailed study of carbamazepine crystal growth in four different bis(urea) gelators, including a metallogelator, is reported. The crystallization of a range of other drug substances, namely sparfloxacin, piroxicam, theophylline, caffeine, ibuprofen, acetaminophen (paracetamol), sulindac and indomethacin, was also achieved in supramolecular gel media without co-crystal formation. In many cases, crystals can be conveniently recovered from the gels by using supramolecular anion-triggered gel dissolution; however, crystals of substances that themselves bind to anions are dissolved by them. Overall, supramolecular gel-phase crystallization offers an extremely versatile new tool in pharmaceutical polymorph screening.

  2. Polarizabilities of the alkali anions: Li- to Fr-.

    PubMed

    Lupinetti, Concetta; Thakkar, Ajit J

    2006-11-21

    Static dipole polarizabilities are calculated for the ground states of the alkali anions from Li- to Fr-. The polarizabilities include scalar relativistic effects at the second-order Douglas-Kroll level and were computed using the finite-field, coupled-cluster CCSD(T) method with large, carefully optimized basis sets. The relativistic polarizabilities increase with Z, reach a maximum at Cs-, and then decrease again unlike their nonrelativistic counterparts which increase monotonically with Z.

  3. Anion receptor compounds for non-aqueous electrolytes

    DOEpatents

    Lee, Hung Sui; Yang, Xiao-Oing; McBreen, James

    2000-09-19

    A new family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI.sup.+ ion in alkali metal batteries.

  4. Kinetics and mechanism of exogenous anion exchange in FeFbpA-NTA: significance of periplasmic anion lability and anion binding activity of ferric binding protein A.

    PubMed

    Heymann, Jared J; Gabricević, Mario; Mietzner, Timothy A; Crumbliss, Alvin L

    2010-02-01

    The bacterial transferrin ferric binding protein A (FbpA) requires an exogenous anion to facilitate iron sequestration, and subsequently to shuttle the metal across the periplasm to the cytoplasmic membrane. In the diverse conditions of the periplasm, numerous anions are known to be present. Prior in vitro experiments have demonstrated the ability of multiple anions to fulfill the synergistic iron-binding requirement, and the identity of the bound anion has been shown to modulate important physicochemical properties of iron-bound FbpA (FeFbpA). Here we address the kinetics and mechanism of anion exchange for the FeFbpA-nitrilotriacetate (NTA) assembly with several biologically relevant anions (citrate, oxalate, phosphate, and pyrophosphate), with nonphysiologic NTA serving as a representative synergistic anion/chelator. The kinetic data are consistent with an anion-exchange process that occurs in multiple steps, dependent on the identity of both the entering anion and the leaving anion. The exchange mechanism may proceed either as a direct substitution or through an intermediate FeFbpA-X* assembly based on anion (X) identity. Our kinetic results further develop an understanding of exogenous anion lability in the periplasm, as well as address the final step of the iron-free FbpA (apo-FbpA)/Fe(3+) sequestration mechanism. Our results highlight the kinetic significance of the FbpA anion binding site, demonstrating a correlation between apo-FbpA/anion affinity and the FeFbpA rate of anion exchange, further supporting the requirement of an exogenous anion to complete tight sequestration of iron by FbpA, and developing a mechanism for anion exchange within FeFbpA that is dependent on the identity of both the entering anion and the leaving anion.

  5. Dual Transport Properties of Anion Exchanger 1

    PubMed Central

    Barneaud-Rocca, Damien; Borgese, Franck; Guizouarn, Hélène

    2011-01-01

    Previous results suggested that specific point mutations in human anion exchanger 1 (AE1) convert the electroneutral anion exchanger into a monovalent cation conductance. In the present study, the transport site for anion exchange and for the cation leak has been studied by cysteine scanning mutagenesis and sulfhydryl reagent chemistry. Moreover, the role of some highly conserved amino acids within members of the SLC4 family to which AE1 belongs has been assessed in AE1 transport properties. The results suggest that the same transport site within the AE1 spanning domain is involved in anion exchange or in cation transport. A functioning mechanism for this transport site is proposed according to transport properties of the different studied point mutations of AE1. PMID:21257764

  6. The OH- anion acting as an acid

    NASA Astrophysics Data System (ADS)

    Huang, Lulu; Massa, Lou; Bernal, Ivan; Karle, Jerome

    2008-01-01

    In the crystalline state, the OH - anion is shown to be capable of acting as a base or as an acid with respect to waters of crystallization to which it is linked by hydrogen bonds. We examined the OH - anion in three crystalline samples and studied its behavior using quantum mechanics. Four quantum mechanical approximations were employed (HF, B3LYP, SVWN, and MP2) to obtain the relative stability of isomers of the H3O2- molecule in the three crystals considered. In one crystal state (LICQIX), the H3O2- anion corresponds to a geometry in which OH- acts as an acid, but not so as a free molecule. The free anion H3O2- has two qualitatively different structures. In one structure, the hydrogen bond is long, while in the other structure, the hydrogen bond is shorter and the hydrogen atom lies at an equal distance between donor and acceptor oxygen atoms.

  7. Preparation of a new polymeric ionic liquid-based monolith for stir cake sorptive extraction and its application in the extraction of inorganic anions.

    PubMed

    Huang, Xiaojia; Chen, Linli; Yuan, Dongxing; Bi, Shangshang

    2012-07-27

    In this study, a novel stir cake sorptive extraction (SCSE) sorbent based on polymeric ionic liquid-based monolith (PILM) for the extraction of inorganic anions was prepared. In the presence of a porogen solvent containing 1-propanol and dimethylformamid, an ionic liquid, 1-ally-3-methylimidazolium chloride was used as monomer to copolymerize in situ with ethylene dimethacrylate to form PILM. 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 detail. The PILM was characterized by elemental analysis, scanning electron microscopy, mercury intrusion porosimetry and infrared spectroscopy. In order to investigate the extraction capacity of PILM-SCSE for inorganic anions, the SCSE was combined with ion chromatography with conductivity detection, F(-), Cl(-), NO(2)(-), Br(-), NO(3)(-), PO(4)(3-) and SO(4)(2-) were selected as detected solutes. Several extractive parameters, including pH values in sample matrix, desorption solvent, extraction and desorption time were optimized. The results showed that 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 0.11-2.08 and 0.37-6.88 μg/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 different water samples include commercial purified water, tab water and river water. Acceptable recoveries and satisfactory repeatability were obtained. To the best of our knowledge, this is the first to use polymeric ionic liquid to enrich inorganic anions.

  8. Probing electron density of H-bonding between cation-anion of imidazolium-based ionic liquids with different anions by vibrational spectroscopy.

    PubMed

    Gao, Yan; Zhang, Liqun; Wang, Yong; Li, Haoran

    2010-03-04

    Attenuated total reflection infrared spectroscopy and density functional theory calculation have been employed to study the spectral properties of imidazolium-based ionic liquids (ILs) with different anions. ILs based on 1-butyl-3-methylimidazolium cation with different anions, OH(-), CF(3)CO(2)(-), HSO(4)(-), H(2)PO(4)(-), Cl(-), PF(6)(-), and BF(4)(-), are investigated in the present work. It has been shown that the C(2)-H stretching vibration of the imidazolium ring is closely related to the electron density of H-bonding between the two closest cations and anions for pure ILs. The electron density of H-bonding between cation and anion with different anions decreases in the order [OH](-) > [H(2)PO(4)](-) > [HSO(4)](-) > [CF(3)CO(2)](-) > [Cl](-) > [BF(4)](-) > [PF(6)](-). For aqueous ILs, with increasing water content, the aromatic C-H stretching vibration of the imidazolium cation showed systematic blue-shifts. Especially for BmimOH, the nu(C(2))(-H) undergoes a drastic blue-shift by 58 cm(-1), suggesting that the formation of the strong hydrogen bonds O-H...O may greatly weaken the electron density of H-bonding between the cation and anion of ILs.

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

    PubMed

    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.

  10. Computational studies of gas phase reactions of carbon chain anions with N and O atoms.

    PubMed

    Yang, Zhibo; Snow, Theodore P; Bierbaum, Veronica M

    2010-10-28

    Experimental studies of gas phase reactions of carbanions with N and O atoms have been reported previously to understand ion chemistry relevant to the interstellar medium. In all cases reactions of anions with O atoms exhibit larger reaction rate constants compared to the corresponding N atom reactions. In addition, the open-shell carbon chain anions exhibit higher reactivities than the corresponding closed-shell species in N atom reactions, whereas similar reactivities were observed for both open and closed-shell anions in O atom reactions. These trends are investigated by the current theoretical study of the reactions of HC(n)(-)(n = 2, 4, and 6) and C(n)(-) (n = 2, 4-7) with N and O atoms. Our results indicate that spin-forbidden processes are the probable pathways in reactions of closed-shell anions HC(n)(-) with N atoms, and spin conversion limits the reaction efficiency. In reactions of open-shell anions C(n)(-) with N atoms, about 50% of the collisions may proceed through spin-allowed barrierless pathways, which results in relatively higher reaction efficiencies than for the closed-shell reactions. For reactions of all anions with O atoms, the spin-allowed barrierless pathways are the only channels, such that all reactions occur with very high efficiencies. This work provides a greater understanding of the influence of spin effects on the reactivities of anion reactions involving N and O atoms that may be important in the interstellar medium.

  11. Preparation and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution.

    PubMed

    Wang, Yu; Gao, Bao-yu; Yue, Wen-wen; Yue, Qin-yan

    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 (SO4(2-), 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.

  12. A new class of organocatalysts: sulfenate anions.

    PubMed

    Zhang, Mengnan; Jia, Tiezheng; Yin, Haolin; Carroll, Patrick J; Schelter, Eric J; Walsh, Patrick J

    2014-09-26

    Sulfenate anions are known to act as highly reactive species in the organic arena. Now they premiere as organocatalysts. Proof of concept is offered by the sulfoxide/sulfenate-catalyzed (1-10 mol%) coupling of benzyl halides in the presence of base to generate trans-stilbenes in good to excellent yields (up to 99%). Mechanistic studies support the intermediacy of sulfenate anions, and the deprotonated sulfoxide was determined to be the resting state of the catalyst.

  13. Anionic Lewis Acids. A Chemical Oxymoron.

    DTIC Science & Technology

    1995-10-17

    NUMBER OF PAGES12 anionic lewis acid ab initio synthesis 1 2 methide FT NMR 16. PRICE CODE imide multi-nule r 17. SECURITY CLASSIFICATION 18...chemically robust, thermally stable, non-toxic, environmentally safe, and cost-effective. One of our current areas of interest involves the synthesis and...developing a predictive knowledge base that can be used to guide the synthesis of new locally electron-deficient anions. Additionally, we proposed to

  14. Antibacterial effect of cationic porphyrazines and anionic phthalocyanine and their interaction with plasmid DNA

    NASA Astrophysics Data System (ADS)

    Hassani, Leila; Hakimian, Fatemeh; Safaei, Elham; Fazeli, Zahra

    2013-11-01

    Resistance to antibiotics is a public health issue and identification of new antibacterial agents is one of the most important goals of pharmacological research. Among the novel developed antibacterial agents, porphyrin complexes and their derivatives are ideal candidates for use in medical applications. Phthalocyanines differ from porphyrins by having nitrogen atoms link the individual pyrrol units. The aza analogues of the phthalocyanines (azaPcs) such as tetramethylmetalloporphyrazines are heterocyclic Pc analogues. In this investigation, interaction of an anionic phthalocyanine (Cu(PcTs)) and two cationic tetrapyridinoporphyrazines including [Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+ complexes with plasmid DNA was studied using spectroscopic and gel electrophoresis methods. In addition, antibacterial effect of the complexes against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was investigated using dilution test method. The results indicated that both porphyrazines have significant antibacterial properties, but Cu(PcTs) has weak antibacterial effect. Compairing the binding of the phthalocyanine and the porphyrazines to DNA demonstrated that the interaction of cationic porphyrazines is stronger than the anionic phthalocyanine remarkably. The extent of hypochromicity and red shift of absorption spectra indicated preferential intercalation of the two porphyrazine into the base pairs of DNA helix. Gel electrophoresis result implied Cu(2,3-tmtppa) and Cu(3,4-tmtppa) are able to perform cleavage of the plasmid DNA. Consequently, DNA binding and cleavage might be one of the antibacterial mechanisms of the complexes.

  15. High Performance Anion Chromatography of Gadolinium Chelates.

    PubMed

    Hajós, Peter; Lukács, Diana; Farsang, Evelin; Horváth, Krisztian

    2016-11-01

    High performance anion chromatography (HPIC) method to separate ionic Gd chelates, [Formula: see text], [Formula: see text], [Formula: see text] and free matrix anions was developed. At alkaline pHs, polydentate complexing agents such as ethylene-diamine-tetraacetate, diethylene-triamine pentaacetate and trans-1,2-diamine-cyclohexane-tetraacetate tend to form stable Gd chelate anions and can be separated by anion exchange. Separations were studied in the simple isocratic chromatographic run over the wide range of pH and concentration of carbonate eluent using suppressed conductivity detection. The ion exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity of Gd chelates. Parameters of optimized resolution between concurrent ions were presented on a 3D resolution surface. The applicability of the developed method is represented by the simultaneous analysis of Gd chelates and organic/inorganic anions. Inductively coupled plasma atomic emission spectroscopy  (ICP-AES) analysis was used for confirmation of HPIC results for Gd. Collection protocols for the heart-cutting procedure of chromatograms were applied. SPE procedures were also developed not only to extract traces of free gadolinium ions from samples, but also to remove the high level of interfering anions of the complex matrices. The limit of detection, the recoverability and the linearity of the method were also presented. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Specific Anion Effects on the Kinetics of Iodination of Acetone.

    PubMed

    Lo Nostro, Pierandrea; Mazzini, Virginia; Ninham, Barry W; Ambrosi, Moira; Dei, Luigi; Baglioni, Piero

    2016-08-18

    Specific ion effects on the kinetics of iodination of acetone in an acidic medium are investigated by UV/Vis spectrophotometry as a function of nature of the acid and temperature. The results indicate that the order of the reaction with respect to acetone is practically unaffected by the composition of the acid while the value of the mixed constant k1 K increases according to the sequence HBranion and of the interaction between the cationic intermediate and the anion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Macrocyclic bis(ureas) as ligands for anion complexation

    PubMed Central

    Kretschmer, Claudia; Dittmann, Gertrud

    2014-01-01

    Summary 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. PMID:25161744

  18. Data on heavy metals and selected anions in the Persian popular herbal distillates.

    PubMed

    Keshtkar, Mozhgan; Dobaradaran, Sina; Soleimani, Farshid; Karbasdehi, Vahid Noroozi; Mohammadi, Mohammad Javad; Mirahmadi, Roghayeh; Ghasemi, Fatemeh Faraji

    2016-09-01

    In this data article, we determined the concentration levels of heavy metals including Pb, Co, Cd, Mn, Mg, Fe and Cu as well as selected anions including [Formula: see text] , [Formula: see text], [Formula: see text] and [Formula: see text] in the most used and popular herbal distillates in Iran. It is well known that heavy metals may pose a serious health hazard due to their bioaccumulation throughout the trophic chain ("Heavy metals (Cd, Cu, Ni and Pb) content in two fish species of Persian Gulf in Bushehr Port, Iran" (Dobaradaran et al., 2013) [1]; "Comparative investigation of heavy metal, trace, and macro element contents in commercially valuable fish species harvested off from the Persian Gulf" (Abadi et al., 2015) [2]) as well as some other environmental pollutions, "Assessment of sediment quality based on acid-volatile sulfide and simultaneously extracted metals in heavily industrialized area of Asaluyeh, Persian Gulf: concentrations, spatial distributions, and sediment bioavailability/toxicity" (Arfaeinia et al., 2016) [3]. The concentration levels of heavy metals and anions in herbal distillates samples were determined using flame atomic absorption spectrometry (FAAS, Varian AA240, Australia) and a spectrophotometer (M501 Single Beam Scanning UV/VIS, UK) respectively.

  19. Anion Exchange Membranes for Alkaline Fuel Cell Applications: The Effects of Cations.

    PubMed

    Sun, Zhe; Lin, Bencai; Yan, Feng

    2017-09-18

    Alkaline anion exchange membrane fuel cells (AEMFCs) are attracting great attention, because of their potential use of non-precious electrocatalysts. Anion exchange membrane (AEM) is one of the key components of AEMFCs. An ideal AEM should possess high hydroxide conductivity and sufficient long-term durability at elevated temperatures in high pH solutions. This review provides recent progresses of alkaline stability behavior of cations (including quaternary ammonium, imidazolium, guanidinium, pyridinium, tertiary sulfonium, phosphonium, benzimidazolium and pyrrolidinium) and their analogous AEMs, which have been investigated by both experimental studies and theoretical calculations. Effects, including conjugated effect, steric hindrance effect, σ-π hyperconjugative effect and electron effect on the alkaline stability of cations and their analogous AEMs have been discussed. The attempt of this article is to give an overview of some key factors, for future design of novel cations, and their analogous AEMs with high alkaline stability. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Quantitative analysis of anions in glycosaminoglycans and application in heparin stability studies.

    PubMed

    Liu, Li; Linhardt, Robert J; Zhang, Zhenqing

    2014-06-15

    The sulfo groups of glycosaminoglycans contribute to their high charge densities, and are critical for the role they play in various physiological and pathophysiological processes. Unfortunately, the sulfo groups can be hydrolyzed to inorganic sulfate. Thus, it is important to monitor the presence of these sulfo groups. In addition, free anions, including chloride, sulfate and acetate, are often present in glycosaminoglycans as a result of multiple purification steps, and their presence also needs to be monitored. In this report, ion chromatography with conductivity detection is used to analyze the anions present in glycosaminoglycans, including heparin, heparan sulfate, chondroitin sulfate and dermatan sulfate. This method allows quantitation over a wide range of concentrations, affording a limit of quantitation of 0.1 ppm and a limit of detection of 0.05 ppm for most anions of interest. The stability of heparin was also studied, providing data on the formation of both sulfate and acetate anions.

  1. Structural diversity and thermochromic properties of iodobismuthate materials containing d-metal coordination cations: observation of a high symmetry [Bi3I11]2- anion and of isolated I- anions.

    PubMed

    Goforth, Andrea M; Tershansy, Meredith A; Smith, Mark D; Peterson, LeRoy; Kelley, Jennifer G; DeBenedetti, William J I; zur Loye, Hans-Conrad

    2011-01-26

    Six new inorganic-organic salts, all containing iodobismuthate anions and d-metal coordination cations, were synthesized solvothermally from reactions of bismuth iodide, a transition metal (M) nitrate salt (M = Co, Fe or Zn), and a heterocyclic, chelating organic ligand: 1,10-phenanthroline (1,10-phen), 3,4,7,8-tetramethyl-1,10-phenanthroline (TMphen), or 2,2':6',2''-terpyridine (tpy). All six compounds were structurally analyzed by single crystal X-ray diffraction, including variable temperature crystallographic analysis to monitor for structural changes. Furthermore, those containing novel anions and achieved in high yield were additionally characterized by solid-state UV visible spectroscopy at room temperature. [Co(1,10-phen)(3)][Bi(3)I(11)] (1), [Fe(1,10-phen)(3)][Bi(3)I(11)] (2), and [Zn(1,10-phen)(3)][Bi(3)I(11)] (3) are isostructural. They crystallize in the monoclinic space group P2(1)/n and contain the unprecedented iodobismuthate anion, [Bi(3)I(11)](2-), which exhibits near D(3h) symmetry and has an unusual arrangement of three cis face-sharing BiI(6) octahedra. [Co(TMPhen)(3)](2)[Bi(2)I(9)][I] (4), which crystallizes in the trigonal space group P-31c, and [Co(tpy)(2)](2)[Bi(2)I(9)][I] (5) and [Zn(tpy)(2)](2)[Bi(2)I(9)][I] (6), which are isostructural and crystallize in the monoclinic space group C2/c, contain the discrete binuclear [Bi(2)I(9)](3-) anion, common in previously reported iodobismuthate compounds. In addition they contain unusual isolated I(-) anions, which are rarely encountered in iodobismuthate phases. Compounds 1-6 show constitutional similarities while utilizing different organic ligands and illustrate the sensitive dependence of reaction conditions on the identity of the halometalate anion formed. Additionally, all six compounds and the starting material BiI(3) are thermochromic; the origin of this behavior is spectroscopically and crystallographically investigated.

  2. Gallium based low-interaction anions

    DOEpatents

    King, Wayne A.; Kubas, Gregory J.

    2000-01-01

    The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

  3. Anionic lipids and the maintenance of membrane electrostatics in eukaryotes

    PubMed Central

    Platre, Matthieu Pierre

    2017-01-01

    ABSTRACT A wide range of signaling processes occurs at the cell surface through the reversible association of proteins from the cytosol to the plasma membrane. Some low abundant lipids are enriched at the membrane of specific compartments and thereby contribute to the identity of cell organelles by acting as biochemical landmarks. Lipids also influence membrane biophysical properties, which emerge as an important feature in specifying cellular territories. Such parameters are crucial for signal transduction and include lipid packing, membrane curvature and electrostatics. In particular, membrane electrostatics specifies the identity of the plasma membrane inner leaflet. Membrane surface charges are carried by anionic phospholipids, however the exact nature of the lipid(s) that powers the plasma membrane electrostatic field varies among eukaryotes and has been hotly debated during the last decade. Herein, we discuss the role of anionic lipids in setting up plasma membrane electrostatics and we compare similarities and differences that were found in different eukaryotic cells. PMID:28102755

  4. Epithelial Anion Transport as Modulator of Chemokine Signaling

    PubMed Central

    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

  5. Epithelial Anion Transport as Modulator of Chemokine Signaling.

    PubMed

    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.

  6. Solubility and transport of cationic and anionic patterned nanoparticles

    NASA Astrophysics Data System (ADS)

    Su, Jiaye; Olvera de La Cruz, Monica; Guo, Hongxia

    2012-01-01

    We analyze bulk diffusion and transport through hydrophobic nanochannels of nanoparticles (NPs) with different hydrophobic-hydrophilic patterns achieved by coating a fraction of the NP sites with positive or negative charges via explicit solvent molecular dynamics simulations. Ten different charge pattern types including Janus charged-hydrophobic NPs are studied. The cationic NPs are more affected by the patterns and have higher diffusion constants and fluxes than their anionic NPs counterparts. The NP-water interaction dependence on surface pattern and field strength explains these observations. The NP-water Coulomb interaction of anionic NPs in the bulk, which are much stronger than the hydrophobic NP-water interactions, are stronger for NPs with higher localized charge, and stronger than in the cationic NPs counterparts. The diffusion and transport of anionic NPs such as proteins and protein charge ladders with the same total charge but different surface charge patterns are slowest for the highest localized charge pattern, which also adsorb strongest onto surfaces. Our model demonstrates the separation (by reverse osmosis, capillary electrophoresis, or chromatography) of cationic NPs, including proteins with equal net charge but different surface charge distributions.

  7. Anion and divalent cation activation of phosphoglycolate phosphatase from leaves.

    PubMed

    Husic, H D; Tolbert, N E

    1984-02-15

    Phosphoglycolate (P-glycolate) phosphatase was purified 223-fold from spinach leaves by (NH4)2SO4 fractionation, DEAE-cellulose chromatography, and Sephadex G-200 chromatography. The partially purified enzyme had a broad pH optimum between 5.6 and 8.0 and was specific for the hydrolysis of P-glycolate with a Km (P-glycolate) of 26 microM. The enzyme was activated by divalent cations including Mg2+, Co2+, Mn2+, and Zn2+, and by anions including Cl-, Br-, NO-3, and HCOO-. Neither anions nor divalent cations activated the enzyme without the other. The P-glycolate phosphatase activities from tobacco leaves or the green algae, Chlamydomonas reinhardtii, also required Mg2+ and were activated by chloride. In addition, the enzyme was allosterically inhibited by ribose 5-phosphate. The activation of P-glycolate phosphatase by both anions and divalent cations and the inhibition by ribose 5-phosphate may be involved in the in vivo regulation of P-glycolate phosphatase activity.

  8. Towards the Rational Design of Ionic Liquid Matrices for Secondary Ion Mass Spectrometry: Role of the Anion

    NASA Astrophysics Data System (ADS)

    Dertinger, Jennifer J.; Walker, Amy V.

    2013-08-01

    The role of the ionic liquid (IL) anion structure on analyte signal enhancements has been systematically investigated in secondary ion mass spectrometry (SIMS) using a variety of samples, including lipids, sterols, polymers, and peptides. Twenty-four ILs were synthesized. The 12 matrix acids were cinnamic acid derivatives. Two bases were employed: 1-methylimidazole and tripropylamine. Three matrices, methylimmidazolium o-coumarate, tripropylammonium o-coumarate, and tripropylammonium 3,4,5-trimethoxycinnamate, were "universal" matrices enhancing all analytes tested. The pKa of the matrix acid does not appear to have a strong effect on analyte ion intensities. Rather, it is observed that a single hydroxyl group on the anion aromatic ring leads to significantly increased molecular ion intensities. No analyte signal enhancements were observed for -CH3, -CF3 and -OCH3 groups present on the aromatic ring. The position of the -OH group on the aromatic ring also alters molecular ion intensity enhancements. As well as the chemical identity and position of substituents, the number of moieties on the aromatic ring may affect the analyte signal enhancements observed. These observations suggest that the activation of the IL anion aromatic ring is important for optimizing analyte signal intensities. The implications for SIMS imaging of complex structures, such as biological samples, are discussed.

  9. Adsorption-desorption behavior of magnetic amine/Fe3O4 functionalized biopolymer resin towards anionic dyes from wastewater.

    PubMed

    Song, Wen; Gao, Baoyu; Xu, Xing; Xing, Lulu; Han, Shuang; Duan, Pijun; Song, Wuchang; Jia, Ruibao

    2016-06-01

    In this work, a new kind of magnetic amine/Fe3O4 functionalized biopolymer resin (amine/Fe3O4-resin) was prepared and applied to remove various anionic dyes from water. Methyl Orange (MO), Reactive Brilliant Red K-2BP (RBR) and Acid Red 18 (AR) were selected as the typical anionic dye for this research. Meanwhile, amine/Fe3O4-resin was characterized by VSM, XRD, FT-IR, SEM, TEM and XPS. Three anionic dyes removed by amine/Fe3O4-resin were investigated using batch adsorption technique, and the parameters including adsorbent dosage, pH, contact time and temperature were considered. Due to a large number of amine groups and high surface areas, amine/Fe3O4-resin exhibited a remarkably high adsorption capacity for all three dyes, reaching 101.0mg/g, 222.2mg/g and 99.4mg/g for RBR, MO and AR at 25°C, respectively. The pseudo second order model and Langmuir model agreed well with the experimental data, and regeneration experiments indicated its merit of separability and reusability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Hydration Leads to Efficient Reactions of the Carbonate Radical Anion with Hydrogen Chloride in the Gas Phase.

    PubMed

    Tang, Wai Kit; van der Linde, Christian; Siu, Chi-Kit; Beyer, Martin K

    2017-01-12

    The carbonate radical anion CO3(•-) is a key intermediate in tropospheric anion chemistry. Despite its radical character, only a small number of reactions have been reported in the literature. Here we investigate the gas-phase reactions of CO3(•-) and CO3(•-)(H2O) with HCl under ultrahigh vacuum conditions. Bare CO3(•-) forms OHCl(•-) with a rate constant of 4.2 × 10(-12) cm(3) s(-1), which corresponds to an efficiency of only 0.4%. Hydration accelerates the reaction, and ligand exchange of H2O against HCl proceeds with a rate of 2.7 × 10(-10) cm(3) s(-1). Quantum chemical calculations reveal that OHCl(•-) is best described as an OH(•) hydrogen bonded to Cl(-), while the ligand exchange product is Cl(-)(HCO3(•)). Under tropospheric conditions, where CO3(•-)(H2O) is the dominant species, Cl(-)(HCO3(•)) is efficiently formed. These reactions must be included in models of tropospheric anion chemistry.

  11. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    NASA Astrophysics Data System (ADS)

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; Vuitton, V.; Crary, F. J.; González-Caniulef, D.; Shebanits, O.; Jones, G. H.; Lewis, G. R.; Waite, J. H.; Cordiner, M.; Taylor, S. A.; Kataria, D. O.; Wahlund, J.-E.; Edberg, N. J. T.; Sittler, E. C.

    2017-08-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q-1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950-1300 km. We report on detections consistently centered between 25.8 and 26.0 u q-1 and between 49.0-50.1 u q-1 which are identified as belonging to the carbon chain anions, CN-/C3N- and/or C2H-/C4H-, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73-74 u q-1 could be attributed to the further carbon chain anions C5N-/C6H- but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q-1) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  12. Gas-Phase Synthesis of Singly and Multiply Charged Polyoxovanadate Anions Employing Electrospray Ionization and Collision Induced Dissociation

    SciTech Connect

    Al Hasan, Naila M.; Johnson, Grant E.; Laskin, Julia

    2013-07-02

    Electrospray ionization mass spectrometry (ESI-MS) combined with in-source fragmentation and tandem mass spectrometry (MS/MS) experiments were used to generate a wide range of singly and multiply charged vanadium oxide cluster anions including VxOy n– and VxOyCln– ions (x = 1–14, y = 2–36, n = 1–3), protonated clusters, and ligand-bound polyoxovanadate anions. The cluster anions were produced by electrospraying a solution of tetradecavanadate, V14O36Cl(L)5 (L = Et4N+, tetraethylammonium), in acetonitrile. Under mild source conditions, ESI-MS generates a distribution of doubly and triply charged VxOyCln– and VxOyCl(L)(n–1)– clusters predominantly containing 14 vanadium atoms as well as their protonated analogs. Accurate mass measurement using a high-resolution LTQ/Orbitrap mass spectrometer (m/Δm = 60,000 at m/z 410) enabled unambiguous assignment of the elemental composition of the majority of peaks in the ESI-MS spectrum. In addition, high-sensitivity mass spectrometry allowed the charge state of the cluster ions to be assigned based on the separation of the major from the much less abundant minor isotope of vanadium. In-source fragmentation resulted in facile formation of smaller VxOyCl(1–2)– and VxOy (1–2)– anions. Collision-induced dissociation (CID) experiments enabled systematic study of the gas-phase fragmentation pathways of the cluster anions originating from solution and from in-source CID. Surprisingly simple fragmentation patterns were obtained for all singly and doubly charged VxOyCl and VxOy species generated through multiple MS/MS experiments. In contrast, cluster anions originating directly from solution produced comparatively

  13. Studies of anions sorption on natural zeolites.

    PubMed

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Structures and energies of the radicals and anions generated from chlorpyrifos.

    PubMed

    Zhang, Yi; Liu, Chang-Zhong; Li, Xiao-Jun; Wang, Zi-Liang; Zhang, Hai-Tang; Miao, Zhi-Guo

    2010-08-01

    The radicals and anions generated from chlorpyrifos by removing a hydrogen atom have been investigated using the hybrid density functional B3PW91 method. The results show that all the radicals have been classified as three groups and their stability order is methylene (radical 1, 3, 5, and 7) > methyl (radical 9, 11 and 13) > ring (15); the anions have the relative energetic order: methyl > methylene > ring. Moreover, some decomposition reactions are also reported. The large HOMO-LUMO gaps indicate that both radicals and anions are predicted to be high-kinetic stable molecules. We also find that radicals 9, 11 and 13 have the highest AEAs and anions 2, 4 and 6 have higher VDEs. Additionally, natural population analysis charges show that there is the lowest Deltaq (0.14) for the C7 and C9 atoms. We hope that our theoretical results may provide a reference for further experiment and practical application.

  15. Cr(VI) removal via anion exchange on a silver-triazolate MOF.

    PubMed

    Li, Li-Li; Feng, Xiao-Quan; Han, Run-Ping; Zang, Shuang-Quan; Yang, Guang

    2017-01-05

    Gram-scale synthesis of a silver-triazolato framework - {[Ag8(tz)6](NO3)2·6H2O}n (1-NO3; tz(-)=3,5-diphenyl-1,2,4-triazolate) - has been achieved, enabling the systematic investigation of its anion-exchange properties. Our experimental results show that the anion-exchange pattern of 1-NO3 conforms to the so-called Hofmeister bias, which has been correlated to the hydrophobic nature of the MOF pores, and can be understood by considering the difference between the hydration energies of the exchanging anions. Furthermore, 1-NO3 displays a fast, efficient, and reversible adsorption of HCrO4(-) (via anion-exchange) from Cr(VI)-containing aqueous solution (Qmax=37.0 Cr mg/g, 303K), rendering it a promising prototype of a recyclable MOF for Cr(VI) removal.

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

    PubMed

    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.

  17. Enhanced liquid-liquid anion exchange using macrocyclic anion receptors: effect of receptor structure on sulphate-nitrate exchange selectivity

    SciTech Connect

    Moyer, Bruce A; Sloop Jr, Frederick {Fred} V; Fowler, Christopher J; Haverlock, Tamara; Kang, Hyun Ah; Delmau, Laetitia Helene; Bau, Diadra; Hossain, Alamgir; Bowman-James, Kristin; Shriver, James A.; Gross, Mr. Dustin E.; Bill, Nathan; Marquez, Manuel; Lynch, Vincent M.; Sessler, Jonathan L.

    2010-01-01

    When certain macrocyclic anion receptors are added to a chloroform solution of the nitrate form of a lipophilic quaternary ammonium salt (methyltri-C8,10-ammonium nitrate, Aliquat 336N), the extraction of sulphate from an aqueous sodium nitrate solution via exchange with the organic-phase nitrate is significantly enhanced. Eight macrocycles were surveyed, including two derivatives of a tetraamide macrocycle, five derivatives of calix[4]pyrrole and -decafluorocalix[5]pyrrole. Under the hypothesis that the enhancement originates from sulphate binding by the anion receptors in the chloroform phase, it was possible to obtain reasonable fits to the sulphate distribution survey data based on the formation of 1:1 and 2:1 receptor:sulphate complexes in the chloroform phase. Apparent 1:1 sulphate-binding constants obtained from the model in this system fell in the range . Comparison of the results for the various anion receptors included in this study reveals that sulphate binding is sensitive to the nature of the substituents on the parent macrocycle scaffolds in a way that does not follow straightforwardly from simple chemical expectations, such as electron-withdrawing effects on hydrogen-bond donor strength.

  18. Phosphorus dendrimers and photodynamic therapy. Spectroscopic studies on two dendrimer-photosensitizer complexes: Cationic phosphorus dendrimer with rose bengal and anionic phosphorus dendrimer with methylene blue.

    PubMed

    Dabrzalska, Monika; Zablocka, Maria; Mignani, Serge; Majoral, Jean Pierre; Klajnert-Maculewicz, Barbara

    2015-08-15

    Dendrimers due to their unique architecture may play an important role in drug delivery systems including chemotherapy, gene therapy and recently, photodynamic therapy as well. We investigated two dendrimer-photosensitizer systems in context of potential use of these systems in photodynamic therapy. The mixtures of an anionic phosphorus dendrimer of the second generation and methylene blue were studied by UV-vis spectroscopy while that of a cationic phosphorus dendrimer (third generation) and rose bengal were investigated by spectrofluorimetric methods. Spectroscopic analysis of these two systems revealed the formation of dendrimer-photosensitizer complexes via electrostatic interactions as well as π stacking. The stoichiometry of the rose bengal-cationic dendrimer complex was estimated to be 7:1 and 9:1 for the methylene blue-anionic dendrimer complex. The results suggest that these polyanionic or polycationic phosphorus dendrimers can be promising candidates as carriers in photodynamic therapy.

  19. Coumarin benzothiazole derivatives as chemosensors for cyanide anions.

    PubMed

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

    2015-06-05

    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.

  20. Dissociation Chemistry of Hydrogen-Deficient Radical Peptide Anions

    NASA Astrophysics Data System (ADS)

    Moore, Benjamin; Sun, Qingyu; Hsu, Julie C.; Lee, Albert H.; Yoo, Gene C.; Ly, Tony; Julian, Ryan R.

    2012-03-01

    The fragmentation chemistry of anionic deprotonated hydrogen-deficient radical peptides is investigated. Homolytic photodissociation of carbon-iodine bonds with 266 nm light is used to generate the radical species, which are subsequently subjected to collisional activation to induce further dissociation. The charges do not play a central role in the fragmentation chemistry; hence deprotonated peptides that fragment via radical directed dissociation do so via mechanisms which have been reported previously for protonated peptides. However, charge polarity does influence the overall fragmentation of the peptide. For example, the absence of mobile protons favors radical directed dissociation for singly deprotonated peptides. Similarly, a favorable dissociation mechanism initiated at the N-terminus is more notable for anionic peptides where the N-terminus is not protonated (which inhibits the mechanism). In addition, collisional activation of the anionic peptides containing carbon-iodine bonds leads to homolytic cleavage and generation of the radical species, which is not observed for protonated peptides presumably due to competition from lower energy dissociation channels. Finally, for multiply deprotonated radical peptides, electron detachment becomes a competitive channel both during the initial photoactivation and following subsequent collisional activation of the radical. Possible mechanisms that might account for this novel collision-induced electron detachment are discussed.

  1. Coumarin benzothiazole derivatives as chemosensors for cyanide anions

    NASA Astrophysics Data System (ADS)

    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.

  2. Removal of Pesticides from Water by Anionic Clays

    NASA Astrophysics Data System (ADS)

    Lakraimi, M.; Legrouri, A.; Barroug, A.; de Roy, A.; Besse, J.-P.

    1999-03-01

    The exchange of chloride ions by ions from the pesticide family 2.4-dichlorophe- noxyacetate (2.4D) in ?Zn-Al-Cl? anionic clay was investigated by X-ray diffraction and infrared spectroscopy. The effects of 2.4D concentration in solution and temperature on the ion exchange were studied. The best sample in terms of crystallinity, was obtained at 100°C with a 2.4D concentration corresponding to the solubility limit of the ion in water. This sample was further characterised by chemical analyses and scanning electron microscopy. The anion intercalation was effected without degradation of the pesticide anion. L'échange des ions chlorure par les ions d'une molécule appartenant à la famille des pesticides 2,4-dichlorophénoxyacétate (2,4D) dans l'argile anionique [Zn-Al-Cl] a été étudiée par diffraction des rayons X et spectroscopie infrarouge. Les influences de la concentration en 2,4D de la solution d'échange et de la température ont été étudiées afin d'optimiser les conditions de l'échange. La meilleure cristallinité a été obtenue à 100°C dans une solution 0.004 M en 2,4D. Une phase préparée dans ces conditions a été caractérisée par analyse chimique et microscopie électronique à balayage. L'échange a été réalisée sans dégradation de l'anion pesticide.

  3. The Anion Paradox in Sodium Taste Reception: Resolution by Voltage-Clamp Studies

    NASA Astrophysics Data System (ADS)

    Ye, Qing; Heck, Gerard L.; Desimone, John A.

    1991-11-01

    Sodium salts are potent taste stimuli, but their effectiveness is markedly dependent on the anion, with chloride yielding the greatest response. The cellular mechanisms that mediate this phenomenon are not known. This "anion paradox" has been resolved by considering the field potential that is generated by restricted electrodiffusion of the anion through paracellular shunts between taste-bud cells. Neural responses to sodium chloride, sodium acetate, and sodium gluconate were studied while the field potential was voltage-clamped. Clamping at electronegative values eliminated the anion effect, whereas clamping at electropositive potentials exaggerated it. Thus, field potentials across the lingual epithelium modulate taste reception, indicating that the functional unit of taste reception includes the taste cell and its paracellular microenvironment.

  4. Anion Responsive TTF-Appended Calix[4]arenes. Synthesis and Study of Two Different Conformers

    PubMed Central

    Lee, Min Hee; Cao, Qian-Yong; Kim, Sung Kuk; Sessler, Jonathan L.

    2011-01-01

    Two new cone- and 1,3-alternate-calix[4]arenes (cone-1 and 1,3-alt-1), bearing four modified TTF (tetrathiafulvalene) substituents on the upper rim, have been synthesized. The binding ability of these two sets of conformers for various anions, including F−, Cl−, Br−, I−, PF6−, ClO4−, HSO4−, CH3COO−, H2PO4−, and HP2O73−, was tested in organic media by monitoring the changes in their UV/vis and 1H NMR spectra as a function of added anion, as well as via cyclovoltammetry (CV) (all anions studied as their respective TBA salts). On the basis of the present findings, we propose that incorporation of four TTF units within an overall calix[4]arene-based recognition framework produces a preorganized receptor system that displays a modest preference for the pyrophosphate (HP2O73−) anion. PMID:21194202

  5. Reactivity of azole anions with CO₂ from the DFT perspective.

    PubMed

    Tang, Huarong; Wu, Chao

    2013-06-01

    Azole anions are key components in CO₂ capture materials that include ionic liquids and porous solids. Herein, we use density functional theory (DFT) and a Langmuir-type adsorption model to study azole anion-CO₂ interactions. Linear CO₂ has to be bent by approximately 45° to form an N-C bond within the azole ring. The energy cost of bending renders CO₂ absorption much more difficult compared to SO₂ absorption. For different azole anions, the number of nitrogen atoms in the ring and the natural bond orbital energy of the reacting nitrogen lone pair, both linearly correlate with the calculated reaction enthalpy and are useful handles for new sorbent designs. Unlike for SO₂, the azole parent architecture (unsubstituted) does not allow successive CO₂ absorption under mild conditions (<0.12 MPa and at room temperature). Experimental CO₂ and SO₂ absorption isotherms are reproduced by using the Langmuir model parameterized with the calibrated DFT reaction enthalpies. This study provides insight for designing azole-based CO₂-capture materials.

  6. Anionic activators for differential sensing with cell-penetrating peptides.

    PubMed

    Montenegro, Javier; Matile, Stefan

    2011-02-01

    The design, synthesis, and evaluation of small peptides with one to three negative charges and one to three hydrazides as key components of membrane-based synthetic sensing systems are reported. Their spontaneous reaction with hydrophobic aldehydes or ketones gives rapid access to small collections of amphiphilic anions. These anionic amphiphiles can activate polycations as anion transporters in lipid-bilayer membranes. Odorants are used as representative hydrophobic aldehydes and ketones, and cell-penetrating peptides (CPPs) as polycationic transporters in fluorogenic vesicles. Different activities obtained with different counterion activators are used to generate multidimensional patterns that can be recognized by principal component and hierarchical cluster analysis to extract unique "fingerprints" for individual analytes (including enantiomers, cis-trans isomers or perfumes as illustrative analyte mixtures). Comparison of the peptide activators reveals that carboxylates perform better than phosphonates. Gemini-like activators containing two carboxylates and two hydrophobic hydrazone tails are best, whereas excessive charges and tails give weaker activities. This result differs from cationic activators of polyanionic transporters such as DNA, which worked best with octopus amphiphiles with one cationic head and four hydrophobic tentacles. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

    SciTech Connect

    Arnold, Don Wesley

    1994-08-01

    Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O3-. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO2, has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO2 molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO2 reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C2- - C11-), and van der Waals clusters (X-(CO2)n, X = I, Br, Cl; n {le} 13 and I- (N2O)n=1--11). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X-(CO2)n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products.

  8. Interactions between anionic and neutral bromine and rare gas atoms

    SciTech Connect

    Buchachenko, Alexei A.; Grinev, Timur A.; Wright, Timothy G.; Viehland, Larry A.

    2008-02-14

    High-quality, ab initio potential energy functions are obtained for the interaction of bromine atoms and anions with atoms of the six rare gases (Rg) from He to Rn. The potentials of the nonrelativistic {sup 2}{sigma}{sup +} and {sup 2}{pi} electronic states arising from the ground-state Br({sup 2}P)-Rg interactions are computed over a wide range of internuclear separations using a spin-restricted version of the coupled cluster method with single and double excitations and noniterative correction to triple excitations [RCCSD(T)] with an extrapolation to the complete basis set limit, from basis sets of d-aug-cc-pVQZ and d-aug-cc-pV5Z quality. These are compared with potentials derived previously from experimental measurements and ab initio calculations. The same approach is used also to refine the potentials of the Br{sup -}-Rg anions obtained previously [Buchachenko et al., J. Chem. Phys. 125, 064305 (2006)]. Spin-orbit coupling in the neutral species is included both ab initio and via an atomic approximation; deviations between two approaches that are large enough to affect the results significantly are observed only in the Br-Xe and Br-Rn systems. The resulting relativistic potentials are used to compute anion zero electron kinetic energy photoelectron spectra, differential scattering cross sections, and the transport coefficients of trace amounts of both anionic and neutral bromine in the rare gases. Comparison with available experimental data for all systems considered proves a very high precision of the present potentials.

  9. Capillary electrophoresis separation of neutral organic compounds, pharmaceutical drugs, proteins and peptides, enantiomers, and anions

    SciTech Connect

    Ding, Wei -Liang

    1999-02-12

    Addition of a novel anionic surfactant, namely lauryl polyoxyethylene sulfate, to an aqueous-acetonitrile electrolyte makes it possible to separate nonionic organic compounds by capillary electrophoresis. Separation is based on differences in the association between analytes and the surfactant. Highly hydrophobic compounds such as polyaromatic hydrocarbons are well separated by this new surfactant. Migration times of analytes can be readily changed over an unusually large range by varying the additive concentration and the proportion of acetonitrile in the electrolyte. Several examples are given, including the separation of four methylbenz[a]anthracene isomers and the separation of normal and deuterated acetophenone. The effect of adding this new surfactant to the acidic electrolyte was also investigated. Incorporation of cetyltrimethylammonium bromide in the electrolyte is shown to dynamically coat the capillary and reverse electroosmotic flow. Chiral recognition mechanism is studied using novel synthetic surfactants as chiral selectors, which are made from amino acids reacting with alkyl chloroformates. A satisfactory separation of both inorganic and organic anions is obtained using electrolyte solutions as high as 5 M sodium chloride using direct photometric detection. The effect of various salts on electrophoretic and electroosmotic mobility is further discussed. Several examples are given under high-salt conditions.

  10. Size Switchable Supramolecular Nanoparticle Based on Azobenzene Derivative within Anionic Pillar[5]arene

    PubMed Central

    Zhang, Cai-Cai; Li, Sheng-Hua; Zhang, Cui-Fang; Liu, Yu

    2016-01-01

    A photo/thermal-switchable supramolecular nanoparticles assembly has been constructed based on an inclusion complex between anionic pillar[5]arene 2C-WP5A and azobenzene derivative Azo-py-OMe (G). The novel anionic pillar[5]arene-based host-guest inclusion complexation was investigated by the 1H NMR titration, 2D ROESY and isothermal titration microcalorimetry (ITC) showing high association constant (Ka) of (2.60 ± 0.06) × 104 M−1 with 1:1 binding stoichiometry. Furthermore, the supramolecular nanoparticles assembly can be conveniently obtained from G and a small amount of 2C-WP5A in aqueous solution, which was so-called “host induced aggregating (HIA)”. The size and morphology of the supramolecular nanoparticles assembly were characterized by TEM and DLS. As a result of the photo/thermal-isomerization of G included in the cavity of 2C-WP5A, the size of these nanoparticles could reversibly change from ~800 nm to ~250 nm, which could switch the solution of this assembly from turbid to clear. PMID:27849055

  11. Size Switchable Supramolecular Nanoparticle Based on Azobenzene Derivative within Anionic Pillar[5]arene

    NASA Astrophysics Data System (ADS)

    Zhang, Cai-Cai; Li, Sheng-Hua; Zhang, Cui-Fang; Liu, Yu

    2016-11-01

    A photo/thermal-switchable supramolecular nanoparticles assembly has been constructed based on an inclusion complex between anionic pillar[5]arene 2C-WP5A and azobenzene derivative Azo-py-OMe (G). The novel anionic pillar[5]arene-based host-guest inclusion complexation was investigated by the 1H NMR titration, 2D ROESY and isothermal titration microcalorimetry (ITC) showing high association constant (Ka) of (2.60 ± 0.06) × 104 M‑1 with 1:1 binding stoichiometry. Furthermore, the supramolecular nanoparticles assembly can be conveniently obtained from G and a small amount of 2C-WP5A in aqueous solution, which was so-called “host induced aggregating (HIA)”. The size and morphology of the supramolecular nanoparticles assembly were characterized by TEM and DLS. As a result of the photo/thermal-isomerization of G included in the cavity of 2C-WP5A, the size of these nanoparticles could reversibly change from ~800 nm to ~250 nm, which could switch the solution of this assembly from turbid to clear.

  12. Interaction of surfactants with block-copolymer systems in the presence of Hofmeister anions

    NASA Astrophysics Data System (ADS)

    Jadoon, Quratulain; Bibi, Iram; Mehmood, Khalid; Sajjad, Saman; Nawaz, Mohsan; Ali, Farman; Bibi, Saira; ur-Rehman, Wajid; Bano, Shakeela; Usman, Mohammad

    2017-03-01

    The interactions of block copolymers poly (ethylene oxide butylene oxide), E58B7 and E58B11 with anionic surfactant sodium dodecyl sulfate and cationic surfactant cetyltrimethylammonium bromide were studied by using different techniques such as surface tension, conductivity, and dynamic light scattering. The effect of salts in the Hofmeister series on polymer-surfactant systems was also investigated. The interactions were found to be dependent on both surfactant and polymer concentrations. The results were utilized to compute different thermodynamic parameters including enthalpy of micellization (ΔH m), entropy of micellization (ΔS m), free energy of adsorption (ΔG ads) and free energy of micellization (ΔG mic). For diblock-copolymer surfactant systems the negative value of (ΔG mic) shows that the process of micelle formation is thermodynamically favorable. The solubilization in surfactant micelles altered the physicochemical properties of the block copolymer. The value of critical aggregation concentration decreases with the addition of Hofmeister anions, and the decrease is more pronounced for sodium fluoride as compared to sodium iodide.

  13. Interaction of β-cyclodextrin-capped CdSe quantum dots with inorganic anions and cations.

    PubMed

    Shang, Zhuo Bin; Hu, Shuang; Wang, Yu; Jin, Wei Jun

    2011-01-01

    A facile method was developed for the preparation of water soluble β-Cyclodextrin (β-CD)-modified CdSe quantum dots (QDs) (β-CD-QDs) by directly replacing the oleic acid ligands on the QDs surface with β-CD in an alkaline aqueous solution. The as-prepared QDs show good stability in aqueous solution for several months. Oxoanions, including phosphoric acid ion, sulphite acid ion and carbonic acid ion, affect the fluorescence of β-CD-QDs. Among them, H(2)PO(4)(-) exhibited the largest quenching effect. For the polyprotic acids (HO)(3)AO, the effect of acidic anions on the fluorescence of β-CD-QDs was in the order: monoanion (HO)(2)AO(2)(-) > dianion (HO)AO(3)(2-) > trianion AO(4)(3-). After photoactivation for several days in the presence of anions at alkaline pH, the β-CD-QDs exhibited strong fluorescence emission. The effect of various heavy and transition metal ions on the fluorescence properties of the β-CD-QDs was investigated further. It was found that Ag(+), Hg(2+) and Co(2+) have significant quenching effect on the fluorescence of the β-CD-QDs. The Stern-Volmer quenching constants increased in the order: Hg(2+) < Co(2+)

  14. Templating irreversible covalent macrocyclization by using anions.

    PubMed

    Kataev, Evgeny A; Kolesnikov, Grigory V; Arnold, Rene; Lavrov, Herman V; Khrustalev, Victor N

    2013-03-11

    Inorganic anions were used as templates in the reaction between a diamine and an activated diacid to form macrocyclic amides. The reaction conditions were found to perform the macrocyclization sufficiently slow to observe a template effect. A number of analytical methods were used to clarify the reaction mechanisms and to show that the structure of the intermediate plays a decisive role in determining the product distribution. For the macrocyclization under kinetic control, it was shown that the amount of a template, the conformational rigidity of building blocks, and the anion affinities of reaction components and intermediates are important parameters that one should take into consideration to achieve high yields.

  15. Electron anions and the glass transition temperature

    PubMed Central

    Sushko, Peter V.; Tomota, Yudai; Hosono, Hideo

    2016-01-01

    Properties of glasses are typically controlled by judicious selection of the glass-forming and glass-modifying constituents. Through an experimental and computational study of the crystalline, molten, and amorphous [Ca12Al14O32]2+ ⋅ (e–)2, we demonstrate that electron anions in this system behave as glass modifiers that strongly affect solidification dynamics, the glass transition temperature, and spectroscopic properties of the resultant amorphous material. The concentration of such electron anions is a consequential control parameter: It invokes materials evolution pathways and properties not available in conventional glasses, which opens a unique avenue in rational materials design. PMID:27559083

  16. Krebs cycle anions in metabolic acidosis.

    PubMed

    Bowling, Francis G; Morgan, Thomas J

    2005-10-05

    For many years it has been apparent from estimates of the anion gap and the strong ion gap that anions of unknown identity can be generated in sepsis and shock states. Evidence is emerging that at least some of these are intermediates of the citric acid cycle. The exact source of this disturbance remains unclear, because a great many metabolic blocks and bottlenecks can disturb the anaplerotic and cataplerotic pathways that enter and leave the cycle. These mechanisms require clarification with the use of tools such as gas chromatography-mass spectrometry.

  17. Improvement of the chromatographic separation performance of an imidazolium ionic liquid functionalized silica column by in situ anion-exchange with dodecyl sulfonate and dodecylbenzene sulfonate anions.

    PubMed

    Sun, Min; Feng, Juanjuan; Chen, Wenjie; Li, Leilei; Duan, Huimin; Luo, Chuannan

    2014-06-01

    The anionic part of ionic liquids can provide additional interactions during chromatographic separations. In this work, the chromatographic separation performance of a silica column functionalized with 1-propyl-3-methylimidazolium chloride ionic liquid was improved by in situ anion-exchange from chloride anions to dodecyl sulfonate anions and dodecylbenzene sulfonate anions. The separation performances of these ionic liquid functionalized phases were investigated and compared with each other using polycyclic aromatic hydrocarbons, phthalates, parabens, and phenols as model compounds. Results indicated that the new columns presented a better chromatographic separation than the original one. This was ascribed retention mechanism from organic anions. The introduction of dodecyl sulfonate anions increased the hydrophobicity of stationary phase. Furthermore, the phenyl groups of dodecylbenzene sulfonate anions could provide an enhanced selectivity to aromatic compounds such as polycyclic aromatic hydrocarbons by π-π interactions. Analysis repeatability of the new columns was satisfactory (RSD of retention time, 0.10-0.40%; RSD of peak area, 0.66-0.84%).

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

    USGS Publications Warehouse

    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.

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

    SciTech Connect

    Wang, Haopeng; Jae Ko, Yeon; Zhang, Xinxing; Gantefoer, Gerd; Bowen, Kit H. E-mail: akandalam@wcupa.edu; Schnoeckel, Hansgeorg; Eichhorn, Bryan W.; Jena, Puru; Kiran, Boggavarapu E-mail: akandalam@wcupa.edu; Kandalam, Anil K. E-mail: akandalam@wcupa.edu

    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.

  20. In vitro inhibition of superoxide anion production and superoxide dismutase activity by zinc in human spermatozoa.

    PubMed

    Gavella, M; Lipovac, V; Vucić, M; Sverko, V

    1999-08-01

    The in vitro effect of zinc on superoxide anion (O2-) generation and on SOD-like activity in spermatozoa of infertile men was investigated. The formation of superoxide anion was stimulated by NADPH and the level of superoxide anion was measured by the reduction of ferricytochrome c. Both Percoll-isolated (n = 14) and washed spermatozoa (n = 14) exposed to 1 mmol/L zinc (60 min, 37 degrees C), released less (p < 0.002 and p < 0.04, respectively) superoxide anions than did zinc-untreated spermatozoa. These results implicate a possible role for zinc as a scavenger of excessive superoxide anions produced by defective spermatozoa in semen after ejaculation. Additionally, zinc was found to dose-dependently inhibit superoxide dismutase (SOD)-like activity of spermatozoa in vitro. The inhibition of SOD-like activity by an equal concentration of zinc (1 mmol/L) was less pronounced in oligospermic (p < 0.002; n = 16) and asthenozoospermic (p < 0.0005; n = 20) than in normozoospermic samples (p < 0.0001; n = 20). This differential ability of zinc to inhibit SOD-like activity may be relevant to the physiological function of spermatozoa in fertilization. The evidence that zinc may elicit an inhibition of both superoxide anion production and SOD-like activity in human spermatozoa, indicate the existence of novel, zinc-related mechanism(s) involved in the oxidative events occurring after ejaculation, with a possible modulatory effect on germ cell function.

  1. Active lucifer yellow secretion in renal proximal tubule: evidence for organic anion transport system crossover.

    PubMed

    Masereeuw, R; Moons, M M; Toomey, B H; Russel, F G; Miller, D S

    1999-05-01

    Recent studies show that organic anion secretion in renal proximal tubule is mediated by distinct sodium-dependent and sodium-independent transport systems. Here we investigated the possibility that organic anions entering the cells on one system can exit into the lumen on a transporter associated with the other system. In isolated rat kidneys perfused with 10 microM lucifer yellow (LY, a fluorescent organic anion) plus 100 micrograms/ml inulin, the LY-to-inulin clearance ratio averaged 1.6 +/- 0.2, indicating net tubular secretion. Probenecid significantly reduced both LY clearance and LY accumulation in kidney tissue. In intact killifish proximal tubules, confocal microscopy was used to measure steady-state LY uptake into cells and secretion into the tubular lumen. Probenecid, p-aminohippurate, and ouabain nearly abolished both uptake and secretion. To this point, the data indicated that LY was handled by the sodium-dependent and ouabain-sensitive organic anion transport system. However, leukotriene C4, an inhibitor of the luminal step for the sodium-independent and ouabain-insensitive organic anion system, reduced luminal secretion of LY by 50%. Leukotriene C4 did not affect cellular accumulation of LY or the transport of fluorescein on the sodium-dependent system. A similar inhibition pattern was found for another fluorescent organic anion, a mercapturic acid derivative of monochlorobimane. Thus, both organic anions entered the cells on the basolateral transporter for the classical, sodium-dependent system, but about half of the transport into the lumen was handled by the luminal carrier for the sodium-independent system, which is most likely the multidrug resistance-associated protein. This is the first demonstration that xenobiotics can enter renal proximal tubule cells on the carrier associated with one organic anion transport system and exit into the tubular lumen on multiple carriers, one of which is associated with a second system.

  2. The effect of anions on the human P2X7 receptor.

    PubMed

    Kubick, Christoph; Schmalzing, Günther; Markwardt, Fritz

    2011-12-01

    P2X7 receptors (P2X7Rs) are nonselective cation channels that are opened by the binding of extracellular ATP and are involved in the modulation of epithelial secretion, inflammation and nociception. Here, we investigated the effect of extracellular anions on channel gating and permeation of human P2X7Rs (hP2X7Rs) expressed in Xenopus laevis oocytes. Two-microelectrode voltage-clamp recordings showed that ATP-induced hP2X7R-mediated currents increased when extracellular chloride was substituted by the organic anions glutamate or aspartate and decreased when chloride was replaced by the inorganic anions nitrate, sulfate or iodide. ATP concentration-response comparisons revealed that substitution of chloride by glutamate decreased agonist efficacy, while substitution by iodide increased agonist efficacy at high ATP concentrations. Meanwhile, the ATP potency remained unchanged. Activation of the hP2X7R at low ATP concentrations via the high-affinity ATP effector site was not affected by the replacement of chloride by glutamate or iodide. To analyze the anion effect on the hP2X7R at the single-molecule level, we performed single-channel current measurements using the patch-clamp technique in the outside-out configuration. Chloride substitution did not affect the single-channel conductance, but the probability that the P2X7R channel was open increased when chloride was replaced by glutamate and decreased when chloride was replaced by iodide. This effect was due to an influence of the anions on the mean closed times of the hP2X7R channel. We conclude that hP2X7R channels are not anion-permeable in physiological Na+-based media and that external anions allosterically affect ion channel opening in the fully ATP4-liganded P2X7R through an extracellular anion binding site.

  3. Further studies on the reconstitution of glucosylceramidase activity by Sap C and anionic phospholipids.

    PubMed

    Salvioli, R; Tatti, M; Ciaffoni, F; Vaccaro, A M

    2000-04-21

    The reconstitution of the activity of the lysosomal enzyme glucosylceramidase requires anionic phospholipids and, at least, a protein factor, saposin C (Sap C). We have previously proposed a mechanism for the glucosylceramidase activation [Vaccaro et al. (1993) FEBS Lett. 336, 159-162] which implies that Sap C promotes the association of the enzyme with anionic phospholipid-containing membranes, thus favoring the contact between the enzyme and its lipid substrate, glucosylceramide. We have further investigated the properties of Sap C using a fluorescent hydrophobic probe such as 4, 4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS). The binding between bis-ANS and Sap C was pH-dependent, indicating that protonation leads to increased exposure of hydrophobic surfaces of Sap C. The interaction of Sap C with membranes, triggered by the development of hydrophobic properties at low pH values, was affected by the content of anionic phospholipids, such as phosphatidylserine or phosphatidylinositol, suggesting that anionic phospholipids have the potential to modulate the insertion of Sap C in the hydrophobic environment of lysosomal membranes. We previously showed that Sap C and anionic phospholipids are both required for the binding of glucosylceramidase to large vesicles. We have presently observed that Sap C is able to promote the association of glucosylceramidase with the lipid surface only when anionic phospholipids exceed a concentration of 5-10%. This level can be reached by summing lower amounts of individual anionic phospholipids, since they have additive effects. The present data extend and refine our model of the mechanism of glucosylceramidase activation and stress the key role of pH, Sap C and anionic phospholipids in promoting the interaction of the enzyme with membranes.

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

    PubMed

    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.

  5. Amplification of anion sensing by disulfide functionalized ferrocene and ferrocene-calixarene receptors adsorbed onto gold surfaces.

    PubMed

    Cormode, David P; Evans, Andrew J; Davis, Jason J; Beer, Paul D

    2010-07-28

    A disulfide functionalized bis-ferrocene urea acyclic receptor and disulfide functionalized mono- and bis-ferrocene amide and urea appended upper rim calix[4]arene receptors were prepared for the fabrication of SAM redox-active anion sensors. 1H NMR and diffusive voltammetric anion recognition investigations revealed each receptor to be capable of complexing and electrochemically sensing anions via cathodic perturbations of the respective receptor's ferrocene/ferrocenium redox couple. SAMs of a ferrocene urea receptor 3 and ferrocene urea calixarene receptor 17 exhibited significant enhanced magnitudes of cathodic response upon anion addition as compared to observed diffusive perturbations. SAMs of 17 were demonstrated to sense the perrhenate anion in aqueous solutions.

  6. Electrosorption-enhanced solid-phase microextraction of trace anions using a platinum plate coated with single-walled carbon nanotubes.

    PubMed

    Li, Quanlong; Ding, Yujing; Yuan, Dongxing

    2011-08-15

    A platinum plate coated with single-walled carbon nanotubes (SWCNTs@Pt) was prepared by means of electrophoretic deposition. Using the SWCNTs@Pt plate, an electrosorption-enhanced solid-phase microextraction (EE-SPME) technique was proposed for the extraction of trace anions in water, described as follows: a positive potential was applied to the SWCNTs@Pt plate to extract F(-), Cl(-), Br(-), NO(3)(-) and SO(4)(2-) from water using electrosorption, and then a negative potential was applied to the plate placed in ultra-pure water for the desorption of the absorbed anions, and finally the desorbed anions were analyzed using ion chromatography (IC). The EE-SPME parameters, including extraction potential and time as well as desorption potential and time, were investigated. An analytical method based on the above procedures, i.e., EE-SPME-IC, was established and used for the analysis of trace anions in water. The results showed that the application of potential on the SWCNTs@Pt plate significantly enhanced the ion extraction efficiency, and an enrichment factor of 15-38 was achieved. The SWCNTs@Pt plate could be used more than 50 times without significant decay. The linear range, the limit of detection (S/N=3), the limit of quantification (S/N=10) and repeatability (n=7) of our EE-SPME-IC method were 1.0-150.0 μg/L, 0.06-0.26 μg/L, 0.19-0.85 μg/L and 2.1-8.0%, respectively. The proposed method was successfully applied for the analysis of trace anions in deionized water, and acceptable recoveries between 65.3 and 121.1% were obtained for the spiked deionized water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Understanding the High Solubility of CO2 in an Ionic Liquid with the Tetracyanoborate Anion

    SciTech Connect

    Babarao, Ravichandar; Dai, Sheng; Jiang, Deen

    2011-01-01

    The ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate, [emim][B(CN){sub 4}], shows greater CO{sub 2} solubility than several popular ionic liquids (ILs) of different anions including [emim]bis(trifluoromethylsulfonyl)imide [emim][Tf{sub 2}N]. Herein, both classical molecular dynamics simulation and quantum mechanical calculations were used to understand the high solubility of CO{sub 2} in the [emim][B(CN){sub 4}] IL. We found that the solubility is dictated by the cation-anion interaction, while the CO{sub 2}-anion interaction plays a secondary role. The atom-atom radial distribution functions (RDFs) between cation and anion show weaker interaction in [emim][B(CN){sub 4}] than in [emim][Tf{sub 2}N]. A good correlation is observed between gas-phase cation-anion interaction energy with CO{sub 2} solubility at 1 bar and 298 K, suggesting that weaker cation-anion interaction leads to higher CO{sub 2} solubility. MD simulation of CO{sub 2} in the ILs showed that CO{sub 2} is closer to the anion than to the cation and that it interacts more strongly with [B(CN){sub 4}] than with [Tf{sub 2}N]. Moreover, a higher volume expansion is observed in [emim][B(CN){sub 4}] than in [emim][Tf{sub 2}N] at different mole fractions of CO{sub 2}. These results indicate that [B(CN){sub 4}] as a small and highly symmetric anion is unique in giving a high CO{sub 2} solubility by interacting weakly with the cation and thus allowing easy creation of cavity for close contact with CO{sub 2}.

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

    PubMed Central

    2016-01-01

    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

  9. Acute and chronic influence of temperature on red blood cell anion exchange.

    PubMed

    Jensen, F B; Wang, T; Brahm, J

    2001-01-01

    Unidirectional (36)Cl(-) efflux via the red blood cell anion exchanger was measured under Cl(-) self-exchange conditions (i.e. no net flow of anions) in rainbow trout Oncorhynchus mykiss and red-eared freshwater turtle Trachemys scripta to examine the effects of acute temperature changes and acclimation temperature on this process. We also evaluated the possible adaptation of anion exchange to different temperature regimes by including our previously published data on other animals. An acute temperature increase caused a significant increase in the rate constant (k) for unidirectional Cl(-) efflux in rainbow trout and freshwater turtle. After 3 weeks of temperature acclimation, 5 degrees C-acclimated rainbow trout showed only marginally higher Cl(-) transport rates than 15 degrees C-acclimated trout when compared at the same temperature. Apparent activation energies for red blood cell Cl(-) exchange in trout and turtle were lower than values reported in endothermic animals. The Q(10) for red blood cell anion exchange was 2.0 in trout and 2.3 in turtle, values close to those for CO(2) excretion, suggesting that, in ectothermic animals, the temperature sensitivity of band-3-mediated anion exchange matches the temperature sensitivity of CO(2) transport (where red blood cell Cl(-)/HCO(3)(-) exchange is a rate-limiting step). In endotherms, such as man and chicken, Q(10) values for red blood cell anion exchange are considerably higher but are no obstacle to CO(2) transport, because body temperature is normally kept constant at values at which anion exchange rates are high. When compared at constant temperature, red blood cell Cl(-) permeability shows large differences among species (trout, carp, eel, cod, turtle, alligator, chicken and man). Cl(-) permeabilities are, however, remarkable similar when compared at preferred body temperatures, suggesting an appropriate evolutionary adaptation of red blood cell anion exchange function to the different thermal niches occupied

  10. Chemiluminescence Imaging of Superoxide Anion Detects Beta-Cell Function and Mass

    PubMed Central

    Bronsart, Laura L.; Stokes, Christian; Contag, Christopher H.

    2016-01-01

    Superoxide anion is produced during normal cellular respiration and plays key roles in cellular physiology with its dysregulation being associated with a variety of diseases. Superoxide anion is a short-lived molecule and, therefore, its homeostatic regulation and role in biology and disease requires dynamic quantification with fine temporal resolution. Here we validated coelenterazine as a reporter of intracellular superoxide anion concentration and used it as a dynamic measure both in vitro and in vivo. Chemiluminescence was dependent upon superoxide anion levels, including those produced during cellular respiration, and concentrations varied both kinetically and temporally in response to physiologically relevant fluctuations in glucose levels. In vivo imaging with coelenterazine revealed that beta cells of the pancreas have increased levels of superoxide anion, which acted as a measure of beta-cell function and mass and could predict the susceptibility of mice to diabetes mellitus. Glucose response and regulation are key elements of cellular physiology and organismal biology, and superoxide anion appears to play a fundamental and dynamic role in both of these processes. PMID:26752052

  11. Chemiluminescence Imaging of Superoxide Anion Detects Beta-Cell Function and Mass.

    PubMed

    Bronsart, Laura L; Stokes, Christian; Contag, Christopher H

    2016-01-01

    Superoxide anion is produced during normal cellular respiration and plays key roles in cellular physiology with its dysregulation being associated with a variety of diseases. Superoxide anion is a short-lived molecule and, therefore, its homeostatic regulation and role in biology and disease requires dynamic quantification with fine temporal resolution. Here we validated coelenterazine as a reporter of intracellular superoxide anion concentration and used it as a dynamic measure both in vitro and in vivo. Chemiluminescence was dependent upon superoxide anion levels, including those produced during cellular respiration, and concentrations varied both kinetically and temporally in response to physiologically relevant fluctuations in glucose levels. In vivo imaging with coelenterazine revealed that beta cells of the pancreas have increased levels of superoxide anion, which acted as a measure of beta-cell function and mass and could predict the susceptibility of mice to diabetes mellitus. Glucose response and regulation are key elements of cellular physiology and organismal biology, and superoxide anion appears to play a fundamental and dynamic role in both of these processes.

  12. Recognition and sensing of biologically relevant anions in alcohol and mixed alcohol-aqueous solutions using charge neutral cleft-like glycol-derived pyridyl-amidothiourea receptors.

    PubMed

    Duke, Rebecca M; McCabe, Thomas; Schmitt, Wolfgang; Gunnlaugsson, Thorfinnur

    2012-04-06

    In this paper, the synthesis and the spectroscopic investigation of new colorimetric receptors for anions 3-6, possessing a glycol chain at the 4-position of the pyridyl ring, and 1 and 2, which lack such a chain, and the X-ray crystal structure of 2 is presented. Structures 3-6 are able to bind to anions in competitive media, such as alcohol or in a mixture of methanol and water, where the anion recognition gives rise to changes in the absorption spectra, which is red-shifted, in 1:1 or 1:2 (sensor/anion) stoichiometry. The anion recognition for 1 and 2 was also investigated in organic solvents and in a 4:1 mixture of DMSO/H(2)O. The binding of 1 to anions such as acetate, phosphate, and fluoride was also evaluated using (1)H NMR in DMSO-d(6).

  13. On the real structure of profiled anion-deficient corundum

    NASA Astrophysics Data System (ADS)

    Maksimov, V. I.; Sokolov, V. I.; Surdo, A. I.; Abashev, R. M.; Yushkova, E. N.

    2017-02-01

    Profiled Al2O3 single crystals grown by Stepanov’s method to obtain anion-deficient composition were characterized by neutron diffraction at T=300 K for the first time. Whereas the main structure motif of investigated crystals is checked to be of corundum-type, the scattering pictures of as-grown crystal demonstrate pronounced anomalies being probably indications on substructure forming. However, neutron scanning of synthesised crystal taken after annealing under restoring conditions reveals additional effects associated with displacement type superstructure.

  14. Structure of (PMo10V2O40)V and (PMo9V3O40)W anions

    SciTech Connect

    Porai-Koshits, M.A.; Sergienko, V.S.; Yurchenko, E.N.

    1986-07-01

    The authors assess several contradicting viewpoints in the literature concerning the possibility of orientational disordering and a pure or modified Keggin structure for the title heteropolyanions and their respective heteropoly acids and suggest a second investigation of the anions.

  15. Vibrationally resolved anion photoelectron spectroscopy of metal clusters

    NASA Astrophysics Data System (ADS)

    Miller, Stephen R.

    Vibrationally resolved anion photoelectron spectroscopy of metal clusters Vibrationally resolved anion photoelectron spectroscopy (APES) and density functional theory (DFT) are applied to the study of structure and reactivity in small metal containing molecules. The studies described fall into two general categories: the study of bare metal clusters and the study of metal/organic ligand reactions. The current lack of spectroscopic data for small, bare gas-phase metal compounds makes the experimental study of such compounds important for understanding structure and bonding in open-shell metallic species. The heteronuclear diatomic anions MCu- (M = Cr, Mo) were prepared in a flowing afterglow ion-molecule reactor, and studied experimentally with APES. Anion and neutral vibrational frequencies and MCu electron affinities were obtained for both systems. The experiments were supplemented by DFT calculations. The combined use of experiment and theory allows for the assignment of both photoelectron spectra, including a reassignment of the CrCu ground state reported in the literature. Similarly, DFT was used to assign the anionic/neutral electronic states observed in the photoelectron spectra of Al3- and Al3O-. The study of partially ligated organometallic complexes offers a means of examining the interactions between metal atoms and individual ligand molecules. DFT was used to assign electronic states observed in the photoelectron spectra of NbC2H2-, NbC4H4 -NbC6H6- and VC6H 6-. Comparison of the NbnHn - (n = 2, 4, 6) spectra (obtained through the reaction of C2 H4 and Nb) with DFT results provides the first direct spectroscopic evidence of the conversion of ethylene to benzene by a gas phase metal atom. Experiments were used to probe the reactivity of Y with C2H 4 in an effort to examine the generality of the metal induced C 2H4 dehydrogenation/cyclization reactions. Some of the key products in the Y reactions were YC2H-, YC 2H2-, and YC6H5 -. However, the results

  16. Fundamental processes in low energy collisions of alkali anions and atoms

    SciTech Connect

    Champion, R.L.; Doverspike, L.D.; Scott, D.M.; Wang, Y.

    1986-01-01

    Negative ion sources often employ alkali metal atoms in one way or another in order to increase their yield. Models which describe equilibrium conditions or the nature of energy transport within these sources require, among other things, information about the two-body cross sections for various scattering channels which involve either alkali negative ions or alkali atoms. The purpose of this report is to provide a brief summary of recent experimental observations in which collisions of alkali anions (M/sup -/) with various atoms and molecules and collisions of H/sup -/ and D/sup -/ with alkali atoms (M) have been investigated. The energy range of the experiments, 5 < E < 500 eV, includes those kinetics energies often found in discharge-type ion sources. The specific experiments which will be discussed focus upon measurements of total cross sections for collisional electron detachment and charge transfer of negative ions. 16 refs., 7 figs.

  17. The Interactions between SP-B Protein and Anionic Lipids Found in Human Lung Surfactant

    NASA Astrophysics Data System (ADS)

    Lee, Ka Yee C.; Lipp, Michael M.; Zasadzinski, Joseph A.; Waring, Alan J.

    1997-03-01

    Several lung pathologies, including neonatal respiratory distress syndrome, are characterized by a failure of the lung surfactant (LS) system to function properly. Utilizing fluorescence and Brewster angle microscopy, we have investigated the phase behavior of monolayers of binary mixtures of anionic lipids found in LS (palmitic acid, and both saturated and unsaturated phosphatidylglycerol) with both the full length SP-B protein and a shorter, 25-amino acid sequence based on its amino terminus. We found that both protein candidates interact specifically yet differently with each of the lipid components, altering their phase behavior to resemble more closely to that of an ideal LS monolayer. The SP-B protein incorporates itself in the lipid monolayer in all cases, and partitions preferentially into the fluid-type phases during phase transitions; its presence drastically changes the collapse mechanism of the monolayer.

  18. Structure of Anion-Conducting Polymers from Waxs and MD Simulations

    NASA Astrophysics Data System (ADS)

    Frisken, Barbara; Tahmasebi, Sepehr; Schibli, Eric; Holdcroft, Steven

    The structure of novel polymers for anion exchange membranes (AEMs) is investigated using wide angle X-ray scattering (WAXS) combined with molecular dynamics (MD) simulations using a united-atom force field model based on the DREIDING force field. The polymers being studied are poly(benzimidazole) (PBI) derivatives including poly(dimethylbenzimidazole) (PDMBI), mesitylene poly(benzimidazole) (mes-PBI), and mesitylene poly(dimethylbenzimidazole) (mes-PDMBI). WAXS reveals an amorphous structure with two main length scales. By comparing simulation results to WAXS data, we attribute features observed in the scattering data to side-to-side spacing between polymer chains and to the parallel-ring stacking of the benzimidazole rings. Overall, we are able to validate the interpretation of scattering data by combining MD simulations and scattering experiments.

  19. 34 CFR 303.15 - Include; including.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Include; including. 303.15 Section 303.15 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION EARLY INTERVENTION PROGRAM FOR INFANTS AND TODDLERS WITH...

  20. 34 CFR 303.15 - Include; including.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 2 2011-07-01 2010-07-01 true Include; including. 303.15 Section 303.15 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION EARLY INTERVENTION PROGRAM FOR INFANTS AND TODDLERS WITH...

  1. Superelectrophilic amidine dications: dealkylation by triflate anion.

    PubMed

    Kovacevic, Luka S; Idziak, Christopher; Markevicius, Augustinas; Scullion, Callum; Corr, Michael J; Kennedy, Alan R; Tuttle, Tell; Murphy, John A

    2012-08-20

    Superelectrophiles: Formamides were designed that when treated with triflic anhydride would be transformed into superelectrophilic amidine dications. These dications were so electrophilic that they underwent in situ dealkylation by the triflate anion (see scheme; Tf = trifluoromethanesulfonyl). DFT calculations were used to determine the mechanistic details of the dealkylation reaction.

  2. Anion-π catalysis: bicyclic products with four contiguous stereogenic centers from otherwise elusive diastereospecific domino reactions on π-acidic surfaces.

    PubMed

    Liu, Le; Cotelle, Yoann; Klehr, Juliane; Sakai, Naomi; Ward, Thomas R; Matile, Stefan

    2017-05-01

    Anion-π interactions have been introduced recently to catalysis. The idea of stabilizing anionic intermediates and transition states on π-acidic surfaces is a new fundamental concept. By now, examples exist for asymmetric enolate, enamine, iminium and transamination chemistry, and the first anion-π enzyme has been created. Delocalized over large aromatic planes, anion-π interactions appear particularly attractive to stabilize extensive long-distance charge displacements during domino processes. Moving on from the formation of cyclohexane rings with five stereogenic centers in one step on a π-acidic surface, we here focus on asymmetric anion-π catalysis of domino reactions that afford bicyclic products with quaternary stereogenic centers. Catalyst screening includes a newly synthesized, better performing anion-π version of classical organocatalysts from cinchona alkaloids, and anion-π enzymes. We find stereoselectivities that are clearly better than the best ones reported with conventional catalysts, culminating in unprecedented diastereospecificity. Moreover, we describe achiral salts as supramolecular chirality enhancers and report the first artificial enzyme that operates in neutral water with anion-π interactions, i.e., interactions that are essentially new to enzymes. Evidence in support of contributions of anion-π interactions to asymmetric catalysis include increasing diastereo- and enantioselectivity with increasing rates, i.e., asymmetric transition-state stabilization in the presence of π-acidic surfaces and inhibition with the anion selectivity sequence NO3(-) > Br(-) > BF4(-) > PF6(-).

  3. Electrochemical cell structure including an ionomeric barrier

    DOEpatents

    Lambert, Timothy N.; Hibbs, Michael

    2017-06-20

    An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

  4. Predicting the Strength of Anion-π Interactions of Substituted Benzenes: the Development of Anion-π Binding Substituent Constants.

    PubMed

    Bagwill, Christina; Anderson, Christa; Sullivan, Elizabeth; Manohara, Varun; Murthy, Prithvi; Kirkpatrick, Charles C; Stalcup, Apryll; Lewis, Michael

    2016-11-23

    A computational study aimed at accurately predicting the strength of the anion-π binding of substituted benzenes is presented. The anion-π binding energies (Ebind) of 37 substituted benzenes and the parent benzene, with chloride or bromide were investigated at the MP2(full)/6-311++G** level of theory. In addition, energy decomposition analysis was performed on 27 selected chloride-arene complexes via symmetry adapted perturbation theory (SAPT), using the SAPT2+ approach. Initial efforts aimed to correlate the anion-π Ebind values with the sum of the Hammett constants σp (Σσp) or σm (Σσm), as done by others. This proved a decent approach for predicting the binding strength of aromatics with electron-withdrawing substituents. For the Cl(-)-substituted benzene Ebind values, the correlation with the Σσp and Σσm values of aromatics with electron-withdrawing groups had r(2) values of 0.89 and 0.87 respectively. For the Br(-)-substituted benzene Ebind values, the correlation with the Σσp and Σσm values of aromatics with electron-withdrawing groups had r(2) values of 0.90 and 0.87. However, adding aromatics with electron-donating substituents to the investigation caused the correlation to deteriorate. For the Cl(-)-substituted benzene complexes the correlation between Ebind values and the Hammett constants had r(2) = 0.81 for Σσp and r(2) = 0.84 for Σσm. For the Br(-)-substituted benzene complexes, the respective r(2) values were 0.71 for Σσp and 0.79 for Σσm. The deterioration in correlation upon consideration of substituted benzenes with electron-donating substituents is due to the anion-π binding energies becoming more attractive regardless of what type of substituent is added to the aromatic. A similar trend has been reported for parallel face-to-face substituted benzene-benzene binding. This is certainly counter to what electrostatic arguments would predict for trends in anion-π binding energies, and this discrepancy is further highlighted

  5. Nucleotide sequence of the tobacco (Nicotiana tabacum) anionic peroxidase gene

    SciTech Connect

    Diaz-De-Leon, F.; Klotz, K.L.; Lagrimini, L.M. )

    1993-03-01

    Peroxidases have been implicated in numerous physiological processes including lignification (Grisebach, 1981), wound-healing (Espelie et al., 1986), phenol oxidation (Lagrimini, 1991), pathogen defense (Ye et al., 1990), and the regulation of cell elongation through the formation of interchain covalent bonds between various cell wall polymers (Fry, 1986; Goldberg et al., 1986; Bradley et al., 1992). However, a complete description of peroxidase action in vivo is not available because of the vast number of potential substrates and the existence of multiple isoenzymes. The tobacco anionic peroxidase is one of the better-characterized isoenzymes. This enzyme has been shown to oxidize a number of significant plant secondary compounds in vitro including cinnamyl alcohols, phenolic acids, and indole-3-acetic acid (Maeder, 1980; Lagrimini, 1991). A cDNA encoding the enzyme has been obtained, and this enzyme was shown to be expressed at the highest levels in lignifying tissues (xylem and tracheary elements) and also in epidermal tissue (Lagrimini et al., 1987). It was shown at this time that there were four distinct copies of the anionic peroxidase gene in tobacco (Nicotiana tabacum). A tobacco genomic DNA library was constructed in the [lambda]-phase EMBL3, from which two unique peroxidase genes were sequenced. One of these clones, [lambda]POD1, was designated as a pseudogene when the exonic sequences were found to differ from the cDNA sequences by 1%, and several frame shifts in the coding sequences indicated a dysfunctional gene (the authors' unpublished results). The other clone, [lambda]POD3, described in this manuscript, was designated as the functional tobacco anionic peroxidase gene because of 100% homology with the cDNA. Significant structural elements include an AS-2 box indicated in shoot-specific expression (Lam and Chua, 1989), a TATA box, and two intervening sequences. 10 refs., 1 tab.

  6. Anionic phospholipids modulate peptide insertion into membranes.

    PubMed

    Liu, L P; Deber, C M

    1997-05-06

    While the insertion of a hydrophobic peptide or membrane protein segment into the bilayer can be spontaneous and driven mainly by the hydrophobic effect, anionic lipids, which comprise ca. 20% of biological membranes, provide a source of electrostatic attractions for binding of proteins/peptides into membranes. To unravel the interplay of hydrophobicity and electrostatics in the binding of peptides into membranes, we designed peptides de novo which possess the typical sequence Lys-Lys-Ala-Ala-Ala-X-Ala-Ala-Ala-Ala-Ala-X-Ala-Ala-Trp-Ala-Ala-X-Ala-Al a-Ala-Lys-Lys-Lys-Lys-amide, where X residues correspond to "guest" residues which encompass a range of hydrophobicity (Leu, Ile, Gly, and Ser). Circular dichroism spectra demonstrated that peptides were partially (40-90%) random in aqueous buffer but were promoted to form 100% alpha-helical structures by anionic lipid micelles. In neutral lipid micelles, only the relatively hydrophobic peptides (X = L and I) spontaneously adopted the alpha-helical conformation, but when 25% of negatively charged lipids were mixed in to mimic the content of anionic lipids in biomembranes, the less hydrophobic (X = S and G) peptides then formed alpha-helical conformations. Consistent with these findings, fluorescence quenching by the aqueous-phase quencher iodide indicated that in anionic (dimyristoylphosphatidylglycerol) vesicles, the peptide Trp residue was buried in the lipid vesicle hydrophobic core, while in neutral (dimyristoylphosphatidylcholine) vesicles, only hydrophobic (X = L and I) peptides were shielded from the aqueous solution. Trp emission spectra of peptides in the presence of phospholipids doxyl-labeled at the 5-, 7-, 10-, 12-, and 16-fatty acid positions implied not only a transbilayer orientation for inserted peptides but also that mixed peptide populations (transbilayer + surface-associated) may arise. Overall results suggest that for hydrophobic peptides with segmental threshold hydrophobicity below that which

  7. Regeneration of anion exchange resins by catalyzed electrochemical reduction

    DOEpatents

    Gu, Baohua; Brown, Gilbert M.

    2002-01-01

    Anion exchange resins sorbed with perchlorate may be regenerated by a combination of chemical reduction of perchlorate to chloride using a reducing agent and an electrochemical reduction of the oxidized reducing agent. Transitional metals including Ti, Re, and V are preferred chemical reagents for the reduction of perchlorate to chloride. Complexing agents such as oxalate are used to prevent the precipitation of the oxidized Ti(IV) species, and ethyl alcohol may be added to accelerate the reduction kinetics of perchlorate. The regeneration may be performed by continuously recycling the regenerating solution through the resin bed and an electrochemical cell so that the secondary waste generation is minimized.

  8. The human erythrocyte anion-transport protein. Partial amino acid sequence, conformation and a possible molecular mechanism for anion exchange.

    PubMed Central

    Brock, C J; Tanner, M J; Kempf, C

    1983-01-01

    The N-terminal 72 residues of an integral membrane fragment, P5, of the human erythrocyte anion-transport protein, which is known to be directly involved in the anion-exchange process, was shown to have the following amino acid sequence: Met-Val-Pro-Lys-Pro-Gln-Gly-Pro-Leu-Pro-Asn-Thr-Ala-Leu-Leu-Ser-Leu-Val-Leu-Met -Ala-Gly-Thr-Phe-Phe-Phe-Ala-Met-Met-Leu-Arg-Lys-Phe-Lys-Asn-Ser-Ser-Tyr-Phe-Pro-Gly-Lys-Leu-Arg-Arg-Val-Ile-Gly-Asp-Phe-Gly-Val-Pro-Ile-Ser-Ile-Leu-Ile-Met-Val-Leu-Val-Asp-Phe-Phe-Ile-Gln-Asp-Thr-Tyr-Thr-Gln- The structure of this fragment was analysed, with account being taken of the constraints that apply to the folding of integral membrane proteins and the topographical locations of various sites in the sequence. It was concluded that this sequence forms two transmembrane alpha-helices. These are probably part of a cluster of amphipathic transmembrane alpha-helices, which could comprise that part of the protein responsible for transport activity. The presently available evidence relating to the anion-exchange process was considered with the structural features noted in this study and a possible molecular mechanism is proposed. In this model the rearrangement of a network of intramembranous charged pairs mediates the translocation of an anion between anion-binding regions at each surface of the membrane, which are composed of clusters of positively charged amino acids. This model imposes a sequential exchange mechanism on the system. Supplementary material, including Tables and Figures describing the compositions of peptides determined by amino acid analysis and sequence studies, quantitative and qualitative data that provide a residue-by-residue justification for the sequence assignment and a description of modifications to and use of the solid-phase sequencer has been deposited as Supplementary Publication SUP 50123 (12 pages) with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be

  9. Quaternary ammonium and phosphonium based ionic liquids: a comparison of common anions.

    PubMed

    Blundell, Rebecca K; Licence, Peter

    2014-08-07

    A series of ammonium-based ionic liquids and their phosphonium analogues have been investigated using X-ray Photoelectron Spectroscopy (XPS). A robust C 1s peak fitting model has been developed and described for the tetraalkylphosphonium and tetraalkylammonium families of ionic liquid, with comparisons made between the two series. Cation-anion interactions have been investigated to determine the impact of changing the cationic core from nitrogen to phosphorus upon the electronic environment of the anion. Comparisons between long and short chain cationic systems are also described.

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

    SciTech Connect

    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.

  11. Anion-π interactions involving [MX(n)](m-) anions: a comprehensive theoretical study.

    PubMed

    Estarellas, Carolina; Quiñonero, David; Deyà, Pere M; Frontera, Antonio

    2013-01-14

    In this manuscript we perform a systematic study on the geometric and energetic features of anion-π complexes, wherein the anion is a metal complex of variable shapes and charges. Such a study is lacking in the literature. For the calculations we used the ab initio RI-MP2/def2-TZVPP level of theory. A search in the Cambridge Structural Database (CSD) provides the experimental starting point that inspired the subsequent theoretical study. The influence of [MX(n)](m-) on the anion-π interaction was analyzed in terms of energetic, geometric, and charge transfer properties and Bader's theory of "atom-in-molecules" (AIM). The binding energy depends on the coordination index, geometric features and different orientations adopted by the metallic anion. The binding mode resembling a stacking interaction for linear, trigonal planar and square-planar anions is the most favorable. For tetrahedral and octahedral anions the most favorable orientation is the one with three halogen atoms pointing to the ring.

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

    PubMed

    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.

  13. Models of Interstellar Anion Chemistry

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    Chemical models are presented for the dense, star-forming interstellar cloud L1527, which contains a class 0/I protostar and exhibits large abundances of carbon-chain-bearing molecules (including CnH, CnH-, HCnN and CH3CCH). We are able to accurately reproduce the observed chemical abundances in this cloud using standard gas-phase chemical models. The two models presented include dust grain accretion and freefall collapse of the cloud, but without the need for any sublimation of mantle ices as the protostar forms and begins to warm the surrounding cloud. Thus, we find that standard gas-phase chemical models may be used to study the chemistry of such regions, and that the so-called "warm carbon-chain chemistry" postulated by Sakai et al. (2008, ApJ, 672, 371) may be due to the presence of left-over carbon chains formed during the earlier, cooler phase of the collapsing cloud. This work was supported by NASA's Origins of Solar Systems Program and by the Goddard Center for Astrobiology.

  14. Acyl anion free N-heterocyclic carbene organocatalysis.

    PubMed

    Ryan, Sarah J; Candish, Lisa; Lupton, David W

    2013-06-21

    Reaction discovery using N-heterocyclic carbene organocatalysis has been dominated by the chemistry of acyl anion equivalents. Recent studies demonstrate that NHCs are far more diverse catalysts, with a variety of reactions discovered that proceed without acyl anion equivalent formation. In this tutorial review selected examples of acyl anion free NHC catalysis using carbonyl compounds are presented.

  15. Enhanced Anion Transport Using Some Expanded Porphyrins as Carriers.

    DTIC Science & Technology

    1991-01-01

    macropolycycles have been studied most extensively as synthetic anion-receptors. They bind a variety of anionic species such as inorganic anions... Caderas , C.; Stepdnek, R.; Kr~utler, B. He/v. Chim. Acia 1984, 67, 1026-1032. (g) Kimura, E. Top. Curr. Chem. 1985. 128, 113-141. See also refs. 4 and

  16. High Yield C-Derivatization of Weakly Coordinating Carborane Anions

    PubMed Central

    Nava, Matthew J.

    2010-01-01

    Unlike the “parent” carborane anion CHB11H11−, halogenated carborane anions such as CHB11H5Br6− can be readily C-functionalized in high yield and purity, enhancing their utility as weakly coordinating anions. PMID:20450167

  17. Halide anion dependence of ionic surfactant adsorption in air/water interface

    NASA Astrophysics Data System (ADS)

    Kim, Doseok; Wang, Wenjie; Sung, Woongmo; Ao, Mingqi; Vaknin, David

    2014-03-01

    It was recently proposed that there is surface excess of halide anions at the air/water interface, and more surface excess of I- than Br- or Cl-, which cannot be explained by Debye-Huckel theory. In case of charged surfaces such as Gibbs monolayer consisting of cationic surfactant molecules, surface excess of anions can also be expected. In this study, by using surface-sensitive grazing angle X-ray fluorescence in conjunction with surface tension measurement, we investigated adsorption behavior of [C12mim]Cl, [C12mim]Br, [C12mim]I aqueous solutions, in which the surface is first covered by [C12mim]+ cations at low concentrations, and the adsorption of the halide anions to this charged interface would follow with the increase in the concentration of solutes. From the surface tension measurements, it was observed that critical micelle concentration of [C12mim]I solution was 4.6 mM, much smaller than that of [C12mim]Cl (16.7 mM) indicating surface activity of surfactant increases with size of halide anions. From X-ray fluorescence, surface excess of halide anion was measured quantitatively from the interface of these solutions. By putting NaCl and NaI in [C12mim]I and [C12mim]Cl solutions, respectively, competition between Cl- and I- adsorption was investigated, to find that I- has stronger adsorption on the charged surface than Cl-.

  18. Influence of anionic salts on bone metabolism in periparturient dairy goats and sheep.

    PubMed

    Liesegang, A

    2008-06-01

    The purpose of the present study was to investigate the influence of diets supplemented with anionic salts on bone metabolism of dairy goats and sheep. Twelve Saanen goats and 12 Ostfrisean milk sheep (fourth lactation) were divided into 2 groups each [sheep control (SC), goat control (GC); sheep anionic salts (SA), goat anionic salts (GA)]. Each group was fed a different diet in the last 10 d of gestation. Groups SC and GC received a normal diet according to the requirements of goats and sheep in this stage of gestation. Groups SA and GA received supplemental anionic salts. The dietary cation-anion difference (DCAD) was +524 (SC) and +515 (GC) vs. -163 (SA) and -164 (GA) mEq/kg of dry matter. Blood and urine samples were collected daily until parturition. Serum Ca, P, Mg, serum crosslaps (CTX), osteocalcin, 1,25-dihydroxy-vitamin D (VITD), urinary pH, and urinary Ca concentrations were analyzed. Bone mineral density and bone mineral content were measured with peripheral quantitative computer tomography. The bone resorption marker CTX showed significant differences between the animals supplemented with anionic salts and the control animals in goats, but not in sheep. The goats receiving anionic salts had greater CTX concentrations throughout the administration of the salts. In sheep, a difference was only observed on the day of parturition. Similar observations were made in VITD concentrations, although a significant difference between the goat groups was only observed 3 d prepartum. The bone formation marker osteocalcin was lower prepartum in the animals supplemented with anionic salts. The urinary pH was lower in the SA and GA animals, whereas urinary Ca concentrations were greater. Bone mineral content and bone mineral density decreased in all groups around parturition. In conclusion, this experiment showed that the addition of anionic salts in goats led to greater bone resorption rates while on this feeding regimen. It can be concluded that the anionic salts

  19. Layered double hydroxides as anion- and cation-exchanging materials

    NASA Astrophysics Data System (ADS)

    Richardson, Mickey Charles

    2007-12-01

    Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared stretching frequency that can be easily observed, and their respective sizes can be observed while intercalated within the interlayer of the LDH. The ability of LDH to incorporate metal cations or any ions/molecules/complexes, that have a postive charge, have not been previously investigated, mainly due to the chemical and physical nature of LDH. The possibility of cationic incorporation with LDH would most likely occur by surface adsorption, lattice metal replacement, or by intercalation into the LDH interlayers. Although infrared spectroscopy finds it main use through the identification of the anions incorporated with LDH, it can also be used to study and identify the various active and inactive bending and stretching modes that the metal hydroxide layers have.

  20. Mass transfer of single- and double-charged anions through an MA-41L anion-exchange membrane

    SciTech Connect

    Kulikova, O.M.; Sharkova, O.V.; Kulikov, S.M.

    1995-02-20

    Selective anion transfer through an MA-41L anion-exchange membrane in the Cl{sup -}-F{sup -}, Cl{sup -}-SO{sub 4}{sup 2-}, F{sup -}-SO{sub 4}{sup 2-}, and F{sup -}-CO{sub 3}{sup 2-} systems has been studied. The feasibility of partial anion separation in the chloride-sulfate system has been demonstrated. The separation of fluoride ions from accompanying anions was found to be practically impossible.

  1. [Hepatocellular transport of bile acids and organic anions in infection and SIRS--evidence for different mechanisms for regulating membrane transport proteins].

    PubMed

    Bolder, U; Thasler, W E; Hofmann, A F; Jauch, K W

    1998-01-01

    The alteration of proinflammatory mediators during sepsis and SIRS results in a large variety of adaptive changes of metabolic and physiologic variables. This study investigated the alterations of hepatocellular transport in a rat sepsis model (LPS i.p.) as well as in a model inducing SIRS by sterile abscess formation (turpentine i.m.). Two bile acids (Cholyltaurine and Chemodeoxycholyltaurine) and one organic anion (Sulfolithocholyltaurine) were used as marker substrates to investigate the time course of hepatocellular transport function. Experiments were performed in isolated perfused rat livers and plasma membrane vesicles. During sepsis, both, the transport of bile acids and that of the organic anion was markedly reduced. In contrast no alteration of transport was detected during SIRS. However, biliary secretion of glutathione (+90%) and bile acid independent bile flow (%) were increased. mRNA levels of bile acid and organic anion transport proteins were reduced. The lowest values were noted 12 h after injection of LPS or turpentine. Almost unchanged kinetic parameters during SIRS pointed to a normal population of transporters with regard to quantity and substrate affinity. Therefore it seems that transcriptional regulation plays an important role for the expression of transport proteins during sepsis, whereas posttranscriptional regulation may be of importance during SIRS. The clinical phenomenon of septic cholestasis including jaundice implies endotoxemia and differenciates against SIRS.

  2. Methods of using ionic liquids having a fluoride anion as solvents

    SciTech Connect

    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.

  3. Experimental approach to the anion problem in DFT calculation of the partial charge transfer during adsorption at electrochemical interfaces

    NASA Astrophysics Data System (ADS)

    Marichev, V. A.

    2005-08-01

    In DFT calculation of the charge transfer (Δ N), anions pose a special problem since their electron affinities are unknown. There is no method for calculating reasonable values of the absolute electronegativity ( χA) and chemical hardness ( ηA) for ions from data of species themselves. We propose a new approach to the experimental measurement of χA at the condition: Δ N = 0 at which η values may be neglected and χA = χMe. Electrochemical parameters corresponding to this condition may be obtained by the contact electric resistance method during in situ investigation of anion adsorption in the particular system anion-metal.

  4. Luminescent hybrid materials of lanthanide β-diketonate and mesoporous host through covalent and ionic bonding with anion metathesis.

    PubMed

    Li, Qiu-Ping; Yan, Bing

    2012-07-28

    Luminescent mesoporous materials were prepared by performing an anion metathesis reaction on ionic liquid modified SBA15, which has imidazolium chloride bridging units. The lanthanide β-diketonate complex anion was successfully anchored onto the SBA15 framework after the anion metathesis reaction. The resulting materials were characterized by FTIR, TEM, TGA, small-angle X-ray powder diffraction (SAXRD) and nitrogen adsorption-desorption isotherms. The photoluminescent properties of these materials were investigated in detail, and the results reveal that these hybrid mesoporous SBA15, prepared through this preparation approach, present favorable photoluminescent behavior such as high luminescent quantum efficiencies and long luminescent lifetimes.

  5. Tautomeric equilibria of 5-fluorouracil anionic species in water.

    PubMed

    Markova, Nadezhda; Enchev, Venelin; Ivanova, Galya

    2010-12-23

    It has long been postulated that rare tautomeric or ionized forms of nucleic acid bases may play a role in mispair formation. Therefore, ab initio quantum chemical investigations on the tautomeric equilibrium in 5-fluorouracil (5FU) and its anions (deprotonated from N1, AN1, and from N3, AN3) and their tautomeric forms in water were performed. The effect of the water as solvent was introduced using solute-solvent clusters (four water molecules). The influence of the water molecules on the tautomeric reactions between different forms was considered by multiple proton transfer mechanisms. We show that when a water dimer is located in the reaction site between the two pairs of N-H and C═O groups, the assistive effect of the water molecules is strengthened. All calculations of the solute-water complexes were carried out at an MP2 level of theory and supplemented with correction for higher order correlation terms at CCSD(T) level, using the 6-31+G(d,p) basis set. The ab initio calculated frequencies and Raman intensities of 5FU and its anions AN1, AN3, and dianion are in good agreement with the experimental Raman frequencies in aqueous solution at different pH. In order to establish the pH-induced structural transformation in the molecule of 5FU, further (1)H, (19)F, and (13)C NMR spectra in water solution for pH = 6.9-13.8 were acquired and the chemical shift alterations were determined as a function of pH. On the basis of NMR spectroscopic data obtained for 5FU in aqueous solution at alkaline pH, we suggest the existence of a mixture of the anionic tautomeric forms predicted by our theoretical calculations.

  6. Spin trapping of nitric oxide by aci anions of nitroalkanes.

    PubMed

    Reszka, Krzysztof J; Bilski, Piotr; Chignell, Colin F

    2004-03-01

    In alkaline solutions, nitroalkanes (RCH2NO2) undergo deprotonation and rearrange to an aci anion (RHC=NO2-), which may function as a spin trap. Using electron paramagnetic resonance (EPR) spectroscopy, we have investigated suitability of aci anions of a series of nitroalkanes (CH3NO2, CH3CH2NO2, CH3(CH2)2NO2, and CH3(CH2)3NO2) to spin trap nitric oxide (*NO). Based on the observed EPR spectra, the general structure of the adducts, formed by addition of *NO to RHC=NO2-, was identified as nitronitroso dianion radicals of general formula [RC(NO)NO2]*2- in strong base (0.5 M NaOH), and as a mono-anion radical [RCH(NO)NO2]*- in alkaline buffers, pH 10-13. The hyperfine splitting on 14N in the -NO2 moiety (11.2-12.48 G) is distinctly different from the splitting on 14N in the -NO moiety of the adducts (5.23-6.5 G). The structure of the adducts was verified using 15N-labeled *NO, which produced radicals, in which triplet due to splitting on 14N (I = 1) in 14NO/aci nitro adducts was replaced by a doublet due to 15N (I = 1/2) in 15NO/aci nitro adducts. EPR spectra of aci nitromethane/NO adduct recorded in NaOH and NaOD (0.5 M) showed that the hydrogen at alpha-carbon can be exchanged for deuterium, consistent with structures of the adducts being [CH(NO)NO2]*2- and [CD(NO)NO2]*2-, respectively. These results indicate that nitroalkanes could potentially be used as prototypes for development of *NO-specific spin traps suitable for EPR analysis.

  7. Nanoheterostructure cation exchange: anionic framework conservation.

    PubMed

    Jain, Prashant K; Amirav, Lilac; Aloni, Shaul; Alivisatos, A Paul

    2010-07-28

    In ionic nanocrystals the cationic sublattice can be replaced with a different metal ion via a fast, simple, and reversible place exchange, allowing postsynthetic modification of the composition of the nanocrystal, while preserving its size and shape. Here, we demonstrate that, during such an exchange, the anionic framework of the crystal is preserved. When applied to nanoheterostructures, this phenomenon ensures that compositional interfaces within the heterostructure are conserved throughout the transformation. For instance, a morphology composed of a CdSe nanocrystal embedded in a CdS rod (CdSe/CdS) was exchanged to a PbSe/PbS nanorod via a Cu(2)Se/Cu(2)S structure. During every exchange cycle, the seed size and position within the nanorod were preserved, as evident by excitonic features, Z-contrast imaging, and elemental line scans. Anionic framework conservation extends the domain of cation exchange to the design of more complex and unique nanostructures.

  8. Anion Solvation in Carbonate-Based Electrolytes

    DOE PAGES

    von Wald Cresce, Arthur; Gobet, Mallory; Borodin, Oleg; ...

    2015-11-16

    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. 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. Moreover, as a mirror effort to prior Li+ solvation studies, this work focuses on the interactions between carbonate-based solvents and two anions (hexafluorophosphate,more » 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.« less

  9. Anion Solvation in Carbonate-Based Electrolytes

    SciTech Connect

    von Wald Cresce, Arthur; Gobet, Mallory; Borodin, Oleg; Peng, Jing; Russell, Selena M.; Wikner, Emily; Fu, Adele; Hu, Libo; Lee, Hung-Sui; Zhang, Zhengcheng; Yang, Xiao-Qing; Greenbaum, Steven; Amine, Khalil; Xu, Kang

    2015-11-16

    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. 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. Moreover, 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.

  10. Electron anions and the glass transition temperature

    SciTech Connect

    Johnson, Lewis E.; Sushko, Peter V.; Tomota, Yudai; Hosono, Hideo

    2016-08-24

    Properties of glasses are typically controlled by judicious selection of the glass-forming and glass-modifying constituents. Through an experimental and computational study of the crystalline, molten, and amorphous [Ca12Al14O32]2+ ∙ (e)2, we demonstrate that electron anions in this system behave as glass-modifiers that strongly affect solidification dynamics, the glass transition temperature, and spectroscopic properties of the resultant amorphous material. Concentration of such electron anions is a consequential control parameter: it invokes materials evolution pathways and properties not available in conventional glasses, which opens a new avenue in rational materials design.

  11. An intracellular anion channel critical for pigmentation.

    PubMed

    Bellono, Nicholas W; Escobar, Iliana E; Lefkovith, Ariel J; Marks, Michael S; Oancea, Elena

    2014-12-16

    Intracellular ion channels are essential regulators of organellar and cellular function, yet the molecular identity and physiological role of many of these channels remains elusive. In particular, no ion channel has been characterized in melanosomes, organelles that produce and store the major mammalian pigment melanin. Defects in melanosome function cause albinism, characterized by vision and pigmentation deficits, impaired retinal development, and increased susceptibility to skin and eye cancers. The most common form of albinism is caused by mutations in oculocutaneous albinism II (OCA2), a melanosome-specific transmembrane protein with unknown function. Here we used direct patch-clamp of skin and eye melanosomes to identify a novel chloride-selective anion conductance mediated by OCA2 and required for melanin production. Expression of OCA2 increases organelle pH, suggesting that the chloride channel might regulate melanin synthesis by modulating melanosome pH. Thus, a melanosomal anion channel that requires OCA2 is essential for skin and eye pigmentation.

  12. Cytosolic nucleotides block and regulate the Arabidopsis vacuolar anion channel AtALMT9.

    PubMed

    Zhang, Jingbo; Martinoia, Enrico; De Angeli, Alexis

    2014-09-12

    The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al(3+) to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell.

  13. Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice.

    PubMed

    Serafim, Karla G G; Navarro, Suelen A; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Fattori, Victor; Cunha, Thiago M; Alves-Filho, Jose C; Cunha, Fernando Q; Casagrande, Rubia; Verri, Waldiceu A

    2015-11-01

    Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.

  14. Stability and Characteristics of the Halogen Bonding Interaction in an Anion-Anion Complex: A Computational Chemistry Study.

    PubMed

    Wang, Guimin; Chen, Zhaoqiang; Xu, Zhijian; Wang, Jinan; Yang, Yang; Cai, Tingting; Shi, Jiye; Zhu, Weiliang

    2016-02-04

    Halogen bonding is the noncovalent interaction between the positively charged σ-hole of organohalogens and nucleophiles. In reality, both the organohalogen and nucleophile could be deprotonated to form anions, which may lead to the vanishing of the σ-hole and possible repulsion between the two anions. However, our database survey in this study revealed that there are halogen bonding-like interactions between two anions. Quantum mechanics calculations with small model complexes composed of halobenzoates and propiolate indicated that the anion-anion halogen bonding is unstable in vacuum but attractive in solvents. Impressively, the QM optimized halogen bonding distance between the two anions is shorter than that in a neutral system, indicating a possibly stronger halogen bonding interaction, which is verified by the calculated binding energies. Furthermore, natural bond orbital and quantum theory of atoms in molecule analyses also suggested stronger anion-anion halogen bonding than that of the neutral one. Energy decomposition by symmetry adapted perturbation theory revealed that the strong binding might be attributed to large induction energy. The calculations on 4 protein-ligand complexes from PDB by the QM/MM method demonstrated that the anion-anion halogen bonding could contribute to the ligands' binding affinity up to ∼3 kcal/mol. Therefore, anion-anion halogen bonding is stable and applicable in reality.

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

    PubMed Central

    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. PMID:23509687

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

    PubMed

    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.

  17. CE-ESI-MS separation of divalent organic and inorganic anions using a tricationic complexing reagent.

    PubMed

    Gerardi, Anthony R; Lin, Xiuli; Breitbach, Zachary S; Armstrong, Daniel W; Colyer, Christa L

    2012-02-01

    A tricationic ion-pairing reagent, 1,3,5-1-butyl-3-methyl-1H-imidazol-3-ium-2,4,6-trimethylbenzene, was used to form complexes with doubly charged anions for their subsequent analysis by capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) in the positive-ion mode. This methodology offers the advantages of greater versatility and sensitivity relative to direct detection of the anions in negative-ion mode, and it can be realized by a number of possible complexation strategies, including pre-column, on-column, and post-column modes. Three model anions, sulfate [SO₄²⁻], thiosulfate [TSFA, S₂O₃²⁻], and benzenedisulfonate [BZDS, C₆H₄(SO₃)₂²⁻], were amenable to complexation with the tricationic reagent, yielding singly charged cations with greater mass-to-charge (m/z) ratios than the native analytes. By utilizing optimized parameters obtained through previous work with dicationic reagents and singly charged anions, including the CE separation buffer composition and pH, the concentration of the dicationic reagent, the mode of complexation, the nebulizing gas pressure, and the sheath liquid composition, it was possible to develop a robust CE-ESI-MS method appropriate for the analysis of divalent anions in a mixture.

  18. Fe electron transfer and atom exchange in goethite: influence of Al-substitution and anion sorption.

    PubMed

    Latta, Drew E; Bachman, Jonathan E; Scherer, Michelle M

    2012-10-02

    The reaction of Fe(II) with Fe(III) oxides and hydroxides is complex and includes sorption of Fe(II) to the oxide, electron transfer between sorbed Fe(II) and structural Fe(III), reductive dissolution coupled to Fe atom exchange, and, in some cases mineral phase transformation. Much of the work investigating electron transfer and atom exchange between aqueous Fe(II) and Fe(III) oxides has been done under relatively simple aqueous conditions in organic buffers to control pH and background electrolytes to control ionic strength. Here, we investigate whether electron transfer is influenced by cation substitution of Al(III) in goethite and the presence of anions such as phosphate, carbonate, silicate, and natural organic matter. Results from (57)Fe Mössbauer spectroscopy indicate that both Al-substitution (up to 9%) and the presence of common anions (PO(4)(3-), CO(3)(2-), SiO(4)(4-), and humic acid) does not inhibit electron transfer between aqueous Fe(II) and Fe(III) in goethite under the conditions we studied. In contrast, sorption of a long-chain phospholipid completely shuts down electron transfer. Using an enriched isotope tracer method, we found that Al-substitution in goethite (10%), does, however, significantly decrease the extent of atom exchange between Fe(II) and goethite (from 43 to 12%) over a month's time. Phosphate, somewhat surprisingly, appears to have little effect on the rate and extent of atom exchange between aqueous Fe(II) and goethite. Our results show that electron transfer between aqueous Fe(II) and solid Fe(III) in goethite can occur under wide range of geochemical conditions, but that the extent of redox-driven Fe atom exchange may be dependent on the presence of substituting cations such as Al.

  19. Anion Binding in Self-Assembled Monolayers in Mesoporous Supports (SAMMS)

    SciTech Connect

    Mattigod, Shas V.; Fryxell, Glen E.; Parker, Kent E.

    2007-02-19

    The binding of various anions to cationic transition metal complexes lining the pores of mesoporous silica is characterized and correlated to anion basicity. By lining the pore surfaces of mesoporous silica with self-assembled monolayer of organosilanes terminated with chemically selective ligands, a powerful new class of heavy metal sorbents has been realized, called self-assembled monolayers on mesoporous supports (SAMMS) [1-18]. When this interfacial functionality is composed of cationic transition metal complexes, a valuable new class of anion exchange material came into being [19]. Yoshitake and co-workers, have extended this concept to include other transition metal cations in similar cationic complexes inside mesoporous silica [20-23]. Other amine-based ligands (including polymer-based systems) were also explored, and the highest binding capacity was found with the diethylenetriamine ligand [20]. This synthetic strategy allows the chemist to easily modify both the metal center and ligand field, thereby tailoring chemical selectivity at multiple levels.

  20. Lowest autodetachment state of the water anion

    NASA Astrophysics Data System (ADS)

    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.

  1. Dual electron transfer pathways from the excited C60 radical anion: enhanced reactivities due to the photoexcitation of reaction intermediates.

    PubMed

    Fujitsuka, Mamoru; Ohsaka, Tatsuya; Majima, Tetsuro

    2015-12-14

    In the present study, electron transfer (ET) processes from excited radical anions have been investigated using dyad molecules including C60. The deactivation process of excited C60˙(-), including the internal conversion from the D1 to the D0 state and the cooling process of the vibrationally hot ground state (D), was observed spectroscopically for the first time. These processes could be unambiguously distinguished by the observation of the stimulated emission from the D1 state. The intramolecular ET processes from the excited C60˙(-) were confirmed by the transient absorption spectra. Clearly, both D1 and D states acted as precursors for the ET, i.e., dual ET pathways were confirmed. The driving force dependence of the ET rates was well characterized by the Marcus theory, which revealed that the forward ET processes are located at the top region of the Marcus parabola. In addition, the ET from the excited imide radical anion to C60 and that from the ground state C60˙(-) to imide were examined. The ET rate from the excited imide radical anion and that from ground state C60˙(-) did not follow the Marcus parabola estimated for the ET from the excited C60˙(-). The observed difference can be attributed to the difference in the energy required to form the reduced spacer (Δ) in the superexchange mechanism. Because the Δ value tends to become smaller for ET processes from excited radical ions, fast and efficient ET processes are expected from these states as demonstrated in the present study.

  2. Chemistry of nitrile anions in the interstellar medium

    SciTech Connect

    Carles, S.; Le Garrec, J.-L.; Biennier, L.; Guillemin, J.-C.

    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.

  3. Corrective Action Investigation Plan for Corrective Action Unit 254: Area 25 R-MAD Decontamination Facility, Nevada Test Site, Nevada (includes ROTC No. 1, date 01/25/1999)

    SciTech Connect

    DOE /NV

    1999-07-29

    This Corrective Action Investigation Plan contains the US Department of Energy, Nevada Operations Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 254 under the Federal Facility Agreement and Consent Order. Corrective Action Unit 254 consists of Corrective Action Site (CAS) 25-23-06, Decontamination Facility. Located in Area 25 at the Nevada Test Site (NTS), CAU 254 was used between 1963 through 1973 for the decontamination of test-car hardware and tooling used in the Nuclear Rocket Development Station program. The CAS is composed of a fenced area measuring approximately 119 feet by 158 feet that includes Building 3126, an associated aboveground storage tank, a potential underground storage area, two concrete decontamination pads, a generator, two sumps, and a storage yard. Based on site history, the scope of this plan is to resolve the problem statement identified during the Data Quality Objectives process that decontamination activities at this CAU site may have resulted in the release of contaminants of concern (COCs) onto building surfaces, down building drains to associated leachfields, and to soils associated with two concrete decontamination pads located outside the building. Therefore, the scope of the corrective action field investigation will involve soil sampling at biased and random locations in the yard using a direct-push method, scanning and static radiological surveys, and laboratory analyses of all soil/building samples. Historical information provided by former NTS employees indicates that solvents and degreasers may have been used in the decontamination processes; therefore, potential COCs include volatile/semivolatile organic compounds, Resource Conservation and Recovery Act metals, petroleum hydrocarbons, polychlorinated biphenyls, pesticides, asbestos, gamma-emitting radionuclides, plutonium, uranium, and strontium-90. The results of this

  4. The dipole bound-to-covalent anion transformation in uracil

    NASA Astrophysics Data System (ADS)

    Hendricks, J. H.; Lyapustina, S. A.; de Clercq, H. L.; Bowen, K. H.

    1998-01-01

    Nucleic acid base anions play an important role in radiation-induced mutagenesis. Recently, it has been shown that isolated (gas-phase) nucleobases form an exotic form of negative ions, namely, dipole bound anions. These are species in which the excess electrons are bound by the dipole fields of the neutral molecules. In the condensed phase, on the other hand, nucleobase anions are known to be conventional (covalent) anions, implying the transformation from one form into the other due to environmental (solvation) effects. Here, in a series of negative ion photoelectron spectroscopic experiments on gas-phase, solvated uracil cluster anions, we report the observation of this transformation.

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

    PubMed

    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.

  6. Ferrocenylbenzobisimidazoles for recognition of anions and cations.

    PubMed

    Alfonso, María; Tárraga, Alberto; Molina, Pedro

    2013-07-01

    The preparation of 2,7-disubstituted benzobisimidazoles decorated with substituents displaying different electrooptical properties is described. The presence of redox, chromogenic, and fluorescent groups at the heteroaromatic core, which acts as ditopic binding site, made these receptors potential candidates as multichannel probes for ions. The triad 4 behaves as a selective redox and fluorescent chemosensor for HSO4(-) and Hg(2+) ions, whereas receptor 5 acts as a redox and chromogenic chemosensor molecule for AcO(-) and SO4(2-) anions. The change in the absorption spectra is accompanied by a color change from yellow to orange, while sensing of Zn(2+), Hg(2+), and Pb(2+) cations is carried out only by electrochemical techniques. Receptor 6 exhibits a remarkable cathodic shift of the oxidation wave only in the presence of AcO(-), H2PO4(-), and HP2O7(3-) anions, whereas addition of Pb(2+) induces an anodic shift. A new low energy band in the absorption spectra, which is responsible for the color change from colorless to pale yellow, and an important increase of the monomer emission band is observed only in the presence of H2PO4(-), and HP2O7(3-) anions. The most salient feature of the receptor 6 is its ability to act as a multichannel (redox, chromogenic, and fluorescent) chemodosimeter for Cu(2+), and Hg(2+) metal cations.

  7. Ionic Liquids with Weakly Coordinating [M(III)(OR(F))4](-) Anions.

    PubMed

    Rupp, Alexander B A; Krossing, Ingo

    2015-09-15

    Ionic liquids (ILs) are defined as salts with melting points below 100 °C. They attracted much attention in the last two decades due to their unique set of properties, including high conductivities, low viscosities, negligible vapor pressure, and high electrochemical resistance. ILs are seen as tunable systems, of which (also in mixtures) up to 10(19) combinations may exist. These properties make ILs interesting candidates for a variety of fundamental to industrial applications. Our addition to this field was weakly coordinating, little interacting anions, the highly fluorinated aluminates [Al(OR(F))4](-) (R(F) = C(CF3)3, C(CH3), (CF3)2, and CH(CF3)2 and later also CH2(CF3)). We have used these anions in a broad spectrum of applications, including the stabilization of reactive cations, (polymerization) catalysis, and conducting salts for cyclic voltammetry or in electrochemical cells. Especially the [Al(Ohfip)4](-) (hfip = CH(CF3)2) anions in combination with asymmetric organic cations turned out to be very well suited for the synthesis of ILs with very low melting points, some even far below 0 °C. Also the analogous borates, [B(OR(F))4](-), were shown to yield ILs, and currently a plethora of such aluminate and borate ILs have been synthesized and thoroughly investigated. In many aspects, at least the [Al(Ohfip)4](-) ILs present almost ideally noninteracting prototype ILs with (nearly) isotropic but weak and flat Coulomb potential. Consequently, their overall interionic interactions are significantly reduced compared with other classes of ILs, resulting in an extraordinarily low degree, or (for short cation chain lengths below six) even complete absence of ion pairing. From thorough analysis of the principles governing the physical properties of this highly fluorinated IL class with minimized interactions, we were able to learn basic principles that could be extended, for example, to the prediction of the principal properties of a wide variety of typical ILs. In

  8. Electron photoejection in carbanions. Progress report, July 1, 1979-June 30, 1980. [Photomethylation of triphenylmethyl anion in DMSO

    SciTech Connect

    Tolbert, L.M.

    1980-01-01

    A systematic study was completed of the mechanism of photomethylation of triphenylmethyl anion in dimethyl sulfoxide. The mechanism includes the intervention of an electron transfer as the primary process, followed by a radical + carbanion reaction to lead to a radical anion, which ultimately restores its odd electron to the original triphenylmethyl radical formed. The photochemistry is extremely well behaved; the quantum yield for the process is concentration independent, no chain processes are initiated, and the photoproducts are concentration invariant. The quantum yield of disappearance of triphenylmethyl anion, which is constant from ca. 400 to 600 nm, shows a remarkable increase at shorter wavelengths, which may represent the onset of photoelectrons.

  9. Corrective Action Investigation Plan for Corrective Action Unit 165: Areas 25 and 26 Dry Well and Washdown Areas, Nevada Test Site, Nevada (including Record of Technical Change Nos. 1, 2, and 3) (January 2002, Rev. 0)

    SciTech Connect

    U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office

    2002-01-09

    This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 165 under the Federal Facility Agreement and Consent Order. Corrective Action Unit 165 consists of eight Corrective Action Sites (CASs): CAS 25-20-01, Lab Drain Dry Well; CAS 25-51-02, Dry Well; CAS 25-59-01, Septic System; CAS 26-59-01, Septic System; CAS 25-07-06, Train Decontamination Area; CAS 25-07-07, Vehicle Washdown; CAS 26-07-01, Vehicle Washdown Station; and CAS 25-47-01, Reservoir and French Drain. All eight CASs are located in the Nevada Test Site, Nevada. Six of these CASs are located in Area 25 facilities and two CASs are located in Area 26 facilities. The eight CASs at CAU 165 consist of dry wells, septic systems, decontamination pads, and a reservoir. The six CASs in Area 25 are associated with the Nuclear Rocket Development Station that operated from 1958 to 1973. The two CASs in Area 26 are associated with facilities constructed for Project Pluto, a series of nuclear reactor tests conducted between 1961 to 1964 to develop a nuclear-powered ramjet engine. Based on site history, the scope of this plan will be a two-phased approach to investigate the possible presence of hazardous and/or radioactive constituents at concentrations that could potentially pose a threat to human health and the environment. The Phase I analytical program for most CASs will include volatile organic compounds, semivolatile organic compounds, Resource Conservation and Recovery Act metals, total petroleum hydrocarbons, polychlorinated biphenyls, and radionuclides. If laboratory data obtained from the Phase I investigation indicates the presence of contaminants of concern, the process will continue with a Phase II investigation to define the extent of contamination. Based on the results of

  10. Membrane process for separating contaminant anions from aqueous solutions of valuable metal anions

    SciTech Connect

    Hepworth, M.T.; Laferty, J.M.

    1980-11-18

    An aqueous solution of at least one valuable oxyanion containing molybdenum, tungsten, vanadium, or uranium is refined to lower the content of contaminant anions such as PO/sub 4//sup -3/, SO/sub 4//sup -2/, NO/sub 3//sup -/, Cl/sup -/, ClO/sub 3//sup -/, and ClO/sub 4//sup -/, by subjecting the solution to electrolysis at a ph of from 0.5 to 4.0 between a cation-permselective membrane and an anion-permselective membrane having tertiary amine or quaternary ammonium anion exchange groups, to cause contaminant anions to pass from the solution into the anolyte. Ammonium molybdates, tungstates, vanadates, and uranates are formed from the thus-refined solution by subjecting it to a second stage of electrolysis at a ph of at least 7 between a cation-permselective membrane and an anion-permselective membrane to cause valuable oxyanions to pass from the solution into an anolyte which comprises an aqueous solution of ammonia and to form the desired ammonium compound.

  11. Anion-exchange mechanisms in bacteria.

    PubMed Central

    Maloney, P C; Ambudkar, S V; Anatharam, V; Sonna, L A; Varadhachary, A

    1990-01-01

    This article discusses the physiological, biochemical, and molecular properties of bacterial anion-exchange reactions, with a particular focus on a family of phosphate (Pi)-linked antiporters that accept as their primary substrates sugar phosphates such as glucose 6-phosphate (G6P), mannose 6-phosphate, or glycerol 3-phosphate. Pi-linked antiporters may be found in both gram-positive and gram-negative cells. As their name suggests, these exchange proteins accept both inorganic and organic phosphates, but the two classes of substrate interact very differently with the protein. Thus, Pi is always accepted with a relatively low affinity, and when it participates in exchange, it is always taken as the monovalent anion. By contrast, when the high-affinity organic phosphates are used, these same systems fail to discriminate between monovalent and divalent forms. Tests of heterologous exchange (e.g., Pi: G6P) indicate that these proteins have a bifunctional active site that accepts a pair of negative charges, whether as two monovalent anions or as a single divalent anion. For this reason, exchange stoichiometry moves between limits of 2:1 and 2:2, according to the ratio of mono- and divalent substrates at either membrane surface. Since G6P has a pK2 within the physiological range (pK of 6.1), this predicts a novel reaction sequence in vivo because internal pH is more alkaline than external pH. Accordingly, one expects an asymmetric exchange as two monovalent G6P anions from the relatively acidic exterior move against a single divalent G6P from the alkaline interior. In this way an otherwise futile self-exchange of G6P can be biased towards a net inward flux driven (indirectly) by the pH gradient. Despite the biochemical complexity exhibited by Pi-linked antiporters, they resemble all other secondary carriers at a molecular level and show a likely topology in which two sets of six transmembrane alpha-helices are connected by a central hydrophilic loop. Speculations on the

  12. Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport

    NASA Astrophysics Data System (ADS)

    Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.

    2002-12-01

    (VI) and I- in the presence of background electrolyte and aqueous Al (III), Cd(II), Ca(II) or cells coated with Al (oxy)hydroxide phases. We use a unique blend of XRD, electrophoretic mobility, SEM, and aqueous geochemistry measurements to quantify the mechanisms of Cr(VI) and I- removal from solution. Our results indicate the removal of both anions is highly dependent on solution pH with significant removal at low pH and diminishing removal at higher pH values, without the presence of cations or precipitates. However, in the presence of aqueous Cd(II) and Ca(II) which adsorbs strongly from pH 3.5-8, the removal of Cr(VI) and I- increases appreciably. Furthermore the loading of the cell surface with small amorphous mineral phases increases adsorption. Aging of the mineral-bacteria composites appears to decrease removal efficiency due to coarsening of the mineral phases and a decrease in charge density. Considering that many geologic environments include both cationic and anionic metal contaminants, our results suggest that mass transport of Cr(VI), I-, and other anions may be affected by ternary complexation or other cation mediated surface reactions in bacteria-bearing systems.

  13. Anion exchange resins as a source of nitrosamines and nitrosamine precursors.

    PubMed

    Flowers, Riley C; Singer, Philip C

    2013-07-02

    Anion exchange resins are important tools for the removal of harmful anionic contaminants from drinking water, but their use has been linked to the presence of carcinogenic nitrosamines in treated drinking water. In bench-scale batch and column experiments, anion exchange resins from a large, representative group were investigated as sources of the nitrosamines N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), and N-nitrosodi-n-butylamine (NDBA) and their precursors. Several resins were found to release high levels (up to >2000 ng/L, orders of magnitude above drinking water regulatory levels) of nitrosamines upon initial rinsing with lab-grade water, with levels subsiding within 50-100 bed volumes of rinsing. Resins released similarly high levels of nitrosamine precursors, with spikes in precursor release triggered by regeneration of resins with sodium chloride or by interruptions in flow resulting in prolonged contact times. Free chlorine or preformed monochloramine in feedwater led to the production of nitrosamines. Resins released different nitrosamines and precursors depending on their functional groups, with some resins releasing as many as three different nitrosamines and their precursors. These findings have significant implications for the pretreatment and appropriate use of anion exchange resins by drinking water utilities and for the production of anion exchange resins by manufacturers.

  14. Mechanisms of Anion and Cation Permeations in the Resting Membrane of a Barnacle Muscle Fiber

    PubMed Central

    Hagiwara, S.; Toyama, K.; Hayashi, H.

    1971-01-01

    The resting membrane of a barnacle muscle fiber is mostly permeable to cations in a solution of pH 7.7 whereas it becomes primarily permeable to anions if the pH is below 4.0. Mechanisms of ion permeation for various monovalent cations and anions were investigated at pH 7.7 and 3.9, respectively. Permeability ratios were obtained from the relationship between the membrane potential and the concentration of the test ions, and ionic conductances from current-voltage relations of the membrane. The permeability sequence for anions (SCN > I > NO3 > Br > ClO3 > Cl > BrO3 > IO3) was different from the conductance sequence for anions (Br, Cl > ClO3, NO3 > SCN). In contrast, the permeability and conductance sequences were identical for cations (K > Rb > Cs > Na > Li). The results suggest that anion permeation is governed by membrane charges while cation permeation is via some electrically neutral mechanism. PMID:5549097

  15. Anion receptors based on halogen bonding with halo-1,2,3-triazoliums.

    PubMed

    Tepper, Ronny; Schulze, Benjamin; Jäger, Michael; Friebe, Christian; Scharf, Daniel H; Görls, Helmar; Schubert, Ulrich S

    2015-03-20

    A systematic series of anion receptors based on bidentate halogen bonding by halo-triazoles and -triazoliums is presented. The influence of the halogen bond donor atom, the electron-withdrawing group, and the linker group that bridges the two donor moieties is investigated. Additionally, a comparison with hydrogen bond-based analogues is provided. A new, efficient synthetic approach to introduce different halogens into the heterocycles is established using silver(I)-triazolylidenes, which are converted to the corresponding halo-1,2,3-triazoliums with different halogens. Comprehensive nuclear magnetic resonance binding studies supported by isothermal titration calorimetry studies were performed with different halides and oxo-anions to evaluate the influence of key parameters of the halogen bond donor, namely, polarization of the halogen and the bond angle to the anion. The results show a larger anion affinity in the case of more charge-dense halides as well as a general preference of the receptors to bind oxo-anions, in particular sulfate, over halides.

  16. Salivary Anionic Changes after Radiotherapy for Nasopharyngeal Carcinoma: A 1-Year Prospective Study

    PubMed Central

    Pow, Edmond H. N.; Chen, Zhuofan; Kwong, Dora L. W.; Lam, Otto L. T.

    2016-01-01

    Objectives To investigate the salivary anionic changes of patients with nasopharyngeal carcinoma (NPC) treated by radiotherapy. Material and Methods Thirty-eight patients with T1-4, N0-2, M0 NPC received conventional radiotherapy. Stimulated whole saliva was collected at baseline and 2, 6 and 12 months after radiotherapy. Salivary anions levels were measured using ion chromatography. Results A reduction in stimulated saliva flow and salivary pH was accompanied by sustained changes in anionic composition. At 2 months following radiotherapy, there was a significant increase in chloride, sulphate, lactate and formate levels while significant reductions in nitrate and thiocyanate levels were found. No further changes in these anion levels were observed at 6 and 12 months. No significant changes were found in phosphate, acetate, or propionate levels throughout the study period. Conclusions Conventional radiotherapy has a significant and prolonged impact on certain anionic species, likely contributing to increased cariogenic properties and reduced antimicrobial capacities of saliva in NPC patients post-radiotherapy. PMID:27031997

  17. Hofmeister effect of anions on calcium translocation by sarcoplasmic reticulum Ca2+-ATPase

    NASA Astrophysics Data System (ADS)

    Tadini-Buoninsegni, Francesco; Moncelli, Maria Rosa; Peruzzi, Niccolò; Ninham, Barry W.; Dei, Luigi; Nostro, Pierandrea Lo

    2015-10-01

    The occurrence of Hofmeister (specific ion) effects in various membrane-related physiological processes is well documented. For example the effect of anions on the transport activity of the ion pump Na+, K+-ATPase has been investigated. Here we report on specific anion effects on the ATP-dependent Ca2+ translocation by the sarcoplasmic reticulum Ca2+-ATPase (SERCA). Current measurements following ATP concentration jumps on SERCA-containing vesicles adsorbed on solid supported membranes were carried out in the presence of different potassium salts. We found that monovalent anions strongly interfere with ATP-induced Ca2+ translocation by SERCA, according to their increasing chaotropicity in the Hofmeister series. On the contrary, a significant increase in Ca2+ translocation was observed in the presence of sulphate. We suggest that the anions can affect the conformational transition between the phosphorylated intermediates E1P and E2P of the SERCA cycle. In particular, the stabilization of the E1P conformation by chaotropic anions seems to be related to their adsorption at the enzyme/water and/or at the membrane/water interface, while the more kosmotropic species affect SERCA conformation and functionality by modifying the hydration layers of the enzyme.

  18. The potentiometric behavior of polymer-supported metallophthalocyanines used as anion-selective electrodes.

    PubMed

    Arvand, M; Pourhabib, A; Shemshadi, R; Giahi, M

    2007-02-01

    Liquid polymer membrane electrodes based on nickel and manganese phthalocyanines were examined for use as anion-selective electrodes. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) membranes, which were directly coated onto the surfaces of graphite electrodes. The resulting electrodes demonstrate near-Nernstian responses over a wide linear range of perchlorate anion (5 x 10(-7) to 1 x 10(-1) M). The electrodes have a fast response time, submicromolar detection limits (5 x 10(-7) M perchlorate), and could be used over a wide pH range of 3.5-10. The influences of lipophilic cationic and anionic additives on the response properties of the electrodes were investigated. The proposed sensors revealed high selectivity for perchlorate over a number of common inorganic and organic anions. The highest selectivity was observed for the electrode based on manganese phthalocyanine in the presence of the lipophilic anionic additive sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. Application of the electrodes to determine perchlorate in tap water and human urine is also reported.

  19. Diagnosis of superoxide anion radical induced in liquids by atmospheric-pressure plasma using superoxide dismutase

    NASA Astrophysics Data System (ADS)

    Tani, Atsushi; Fukui, Satoshi; Ikawa, Satoshi; Kitano, Katsuhisa

    2015-01-01

    To confirm the formation of the superoxide anion radical (O2-•) in liquids by atmospheric-pressure plasma, we investigated plasma-induced radical species in water using the electron spin resonance (ESR) spin-trapping technique combined with two proteins: superoxide dismutase (SOD), which has enzymatic activity to quench the superoxide anion radical, and bovine serum albumin (BSA), which does not have this enzymatic activity. Different setups of contact and non-contact atmospheric-pressure helium plasma were tested with an additional supply of oxygen gas. For each setup of plasma, no superoxide anion adduct ESR signal was observed in the aqueous solution with SOD, whereas the ESR signal appears in the samples with BSA and without any additive proteins. This means that a superoxide anion radical in the solution is sufficiently quenched by SOD before the formation of the spin adduct. The superoxide anion radical is actually induced in an aqueous solution by atmospheric-pressure plasma when ambient gases contain oxygen.

  20. Hofmeister effect of anions on calcium translocation by sarcoplasmic reticulum Ca2+-ATPase

    PubMed Central

    Tadini-Buoninsegni, Francesco; Moncelli, Maria Rosa; Peruzzi, Niccolò; Ninham, Barry W.; Dei, Luigi; Nostro, Pierandrea Lo

    2015-01-01

    The occurrence of Hofmeister (specific ion) effects in various membrane-related physiological processes is well documented. For example the effect of anions on the transport activity of the ion pump Na+, K+-ATPase has been investigated. Here we report on specific anion effects on the ATP-dependent Ca2+ translocation by the sarcoplasmic reticulum Ca2+-ATPase (SERCA). Current measurements following ATP concentration jumps on SERCA-containing vesicles adsorbed on solid supported membranes were carried out in the presence of different potassium salts. We found that monovalent anions strongly interfere with ATP-induced Ca2+ translocation by SERCA, according to their increasing chaotropicity in the Hofmeister series. On the contrary, a significant increase in Ca2+ translocation was observed in the presence of sulphate. We suggest that the anions can affect the conformational transition between the phosphorylated intermediates E1P and E2P of the SERCA cycle. In particular, the stabilization of the E1P conformation by chaotropic anions seems to be related to their adsorption at the enzyme/water and/or at the membrane/water interface, while the more kosmotropic species affect SERCA conformation and functionality by modifying the hydration layers of the enzyme. PMID:26435197