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Sample records for volume-sensitive osmolyte anion

  1. Protolichesterinic acid, isolated from the lichen Cetraria islandica, reduces LRRC8A expression and volume-sensitive release of organic osmolytes in human lung epithelial cancer cells

    DEFF Research Database (Denmark)

    Thorsteinsdottir, Unnur Arna; Thorsteinsdottir, Margret; Lambert, Ian Henry

    2016-01-01

    We have tested the effect of protolichesterinic acid (PA) on the activity of the volume-sensitive release pathway for the organic osmolyte taurine (VSOAC) and the expression of the leucine-rich-repeat-channel 8A (LRRC8A) protein, which constitutes an essential VSOAC component. Exposing human lung...... of apoptosis) and p21 (regulator of cell cycle progression), respectively. PA reduces cell viability by 30% but has no effect on p21/Bax expression. This excludes PA as a pro-apoptotic drug in A549 cells....... cancer cells (A549) to PA (20 μg/mL, 24 h) reduces LRRC8A protein expression by 25% and taurine release following osmotic cell swelling (320 → 200 mOsm) by 60%. C75 (20 μg/mL, 24 h), a γ-lactone with a C8 carbon fatty acid chain, reduces VSOAC activity by 30%, i.e. less than PA. Stearic acid (20 μg......, excluding that PA mediated inhibition of VSOAC involves 5-LO inhibition. A549 cells exposed to the chemotherapeutic drug cisplatin (10 μM, 24 h) reveal signs of apoptosis, i.e. 25% reduction in cell viability as well as 1.3-, 1.5- and 3.3-fold increase in the expression of LRRC8A, Bax (regulator...

  2. Organic 'compensatory' osmolytes in osmolarity control and ...

    African Journals Online (AJOL)

    1997-09-02

    Sep 2, 1997 ... In animal cells, which lack rigid and highly resistant walls, cell osmoregulation is .... been identifIed as major organic osmolytes in animal cells. (Figure 3). ...... and betaine in mammalian cells in culture. Am. J. Physiol. 258:.

  3. Acute cholesterol depletion leads to net loss of the organic osmolyte taurine in Ehrlich Lettré tumor cells

    DEFF Research Database (Denmark)

    Villumsen, Kasper Rømer; Duelund, Lars; Lambert, Ian Henry

    2010-01-01

    In mammalian cells, the organic osmolyte taurine is accumulated by the Na-dependent taurine transporter TauT and released though the volume- and DIDS-sensitive organic anion channel. Incubating Ehrlich Lettré tumor cells with methyl-ß-cyclodextrin (5 mM, 1 h) reduces the total cholesterol pool...

  4. Organic and inorganic osmolytes at lipid membrane interfaces

    DEFF Research Database (Denmark)

    Westh, P.; Peters, Günther H.j.

    2008-01-01

    on membrane–osmolyte interactions. The physical properties of lipid membranes are strongly affected by the presence of “foreign molecules”—that is, components other than water and lipids—at the interface. In many cases, the solute-induced perturbations are rather complex and cannot be rationalized......This chapter discusses the interactions of organic osmolytes and membranous interfaces, and the effects of these interactions on the properties of the membrane. It also includes a treatment of inorganic ions at the membrane interface since osmolyte effects involve a balance between organic...

  5. Organic and inorganic osmolytes at lipid membrane interfaces

    DEFF Research Database (Denmark)

    Westh, P.; Peters, Günther H.j.

    2008-01-01

    This chapter discusses the interactions of organic osmolytes and membranous interfaces, and the effects of these interactions on the properties of the membrane. It also includes a treatment of inorganic ions at the membrane interface since osmolyte effects involve a balance between organic...... and inorganic components. Before turning to the physicochemical discussion of interfacial interactions, the chapter outlines some central parts of the biology and biotechnology of organic osmolytes. It reviews the central relationships in preferential interaction theory, which we use in subsequent paragraphs...

  6. Effects of osmolytes on protein folding and aggregation in cells.

    Science.gov (United States)

    Ignatova, Zoya; Gierasch, Lila M

    2007-01-01

    Nature has developed many strategies to ensure that the complex and challenging protein folding reaction occurs in vivo with adequate efficiency and fidelity for the success of the organism. Among the strategies widely employed in a huge range of species and cell types is the elaboration of small organic molecules called osmolytes that offset the potentially damaging effects of osmotic stress. While considerable knowledge has been gained in vitro regarding the influence of osmolytes on protein structure and folding, it is of great interest to probe the effects of osmolytes in cells. We have developed an in-cell fluorescent-labeling method that enables the study of protein stability and also protein aggregation in vivo. We utilize a genetically encoded tag called a tetra-Cys motif that binds specifically to a bis-arsenical fluorescein-based dye "FlAsH"; we inserted the tetra-Cys motif into a protein of interest in such a way that the FlAsH signal reported on the state of folding or aggregation of the protein. Then, we designed protocols to assess how various osmolytes influence the stability and propensity to aggregate of our protein of interest. These are described here. Not only are there potential biotechnological applications of osmolytes in the quest to produce greater quantities of well-folded proteins, but also osmolytes may serve as tools and points of departure for therapeutic intervention in protein folding and aggregation diseases. Having in vivo methods to analyze how osmolytes affect folding and aggregation enhances our ability to further these goals greatly.

  7. Hydration and Ion Binding of the Osmolyte Ectoine.

    Science.gov (United States)

    Eiberweiser, Andreas; Nazet, Andreas; Kruchinin, Sergey E; Fedotova, Marina V; Buchner, Richard

    2015-12-10

    Ectoine is a widespread osmolyte enabling halophilic bacteria to withstand high osmotic stress that has many potential applications ranging from cosmetics to its use as a therapeutic agent. In this contribution, combining experiment and theory, the hydration and ion-binding of this zwitterionic compound was studied to gain information on the functioning of ectoine in particular and of osmolytes in general. Dielectric relaxation spectroscopy was used to determine the effective hydration number of ectoine and its effective dipole moment in aqueous solutions with and without added NaCl. The obtained experimental data were compared with structural results from 1D-RISM and 3D-RISM calculations. It was found that ectoine is strongly hydrated, even in the presence of high salt concentrations. Upon addition of NaCl, ions are bound to ectoine but the formed complexes are not very stable. Interestingly, this osmolyte strongly rises the static relative permittivity of its solutions, shielding thus effectively long-range Coulomb interactions among ions in ectoine-containing solutions. We believe that via this effect, which should be common to all zwitterionic osmolytes, ectoine protects against excessive ions within the cell in addition to its strong osmotic activity protecting against ions outside.

  8. Influence of ultraviolet A radiation on osmolytes transport in human retinal pigment epithelial cells

    Directory of Open Access Journals (Sweden)

    Da-Yang Wu

    2014-04-01

    Full Text Available AIM: To demonstrate that ultraviolet A(UVAinduces osmolytes accumulation in retinal pigment epithelial(RPEcells.METHODS: Under different experimental conditions such as UVA exposure, hyperosmotic stress condition and hypoosmotic stress condition, RPE cells were cultured for different time periods. The betaine /γ-amino- n-butyric acid(GABAtransporter, the sodium-dependent myoinositol transporter and the taurine transporter(TAUTmRNA were measured by quantitative PCR. The radioactive labeled osmolytes were measured to evaluate the level of osmolytes transportation. RESULTS: This study demonstrated that RPE expressed mRNA specific for the betaine/GABA transporter, for the sodium-dependent myoinositol transporter and for the TAUT. In comparison to norm osmotic(300mosmol/Lcontrols, a 3-5-fold induction of mRNA expression for the betaine/GABA transporter, the sodium-dependent myoinositol transporter and the TAUT was observed within 6-24h after hyperosmotic exposure(400mosmol/L. Expression of osmolyte transporters was associated with an increased uptake of radioactive labeled osmolytes. Conversely, hypoosmotic(200mosmol/Lstimulation induced significant efflux of these osmolytes. UVA significantly stimulated osmolyte uptake. Increased osmolyte uptake was associated with upregulation of mRNA steady-state levels for osmolyte transporters in irradiated cells.CONCLUSION: UVA induces osmolyte uptake in RPE. It is similar reaction to hyperosmotic stress. This suggests that osmolyte uptake response by UVA may be important to maintain homeostasis.

  9. Effect of ultraviolet A exposure on transport of compatible organic osmolytes in human lens epithelial cells.

    Science.gov (United States)

    Wu, D Y; Zhang, J S

    2015-05-18

    Compatible organic osmolytes, such as betaine, myoinositol, and taurine, are involved in antioxidant defense, protein stabilization, and stress responses. This osmolyte strategy requires the expression of specific osmolyte transporters such as betaine (BGT-1), myoinositol (SMIT), and taurine (TAUT). In contrast to the kidney, keratinocytes, and neural cells, few studies have examined osmolytes in human lens epithelial cells (HLECs). We examined the expression of mRNA specific for BGT-1, SMIT, and TAUT in HLECs. In comparison to normoosmotic (305 mOsM) controls, there was a 3-5-fold time-dependent reaction of BGT-1, SMIT, and TAUT mRNA levels in HLECs exposed to hyperosmotic stress (405 mOsM). Maximal responses were obtained for BGT-1, SMIT, and TAUT mRNA expression after 3, 24 and 9 h of hyperosmotic exposure, respectively. This expression was correlated with increased osmolyte uptake. In contrast, hypoosmotic (205 mOsM) stimulation led to a significant efflux of osmolytes. Exposure to ultraviolet A (340-400 nm) radiation significantly stimulated osmolyte uptake. Increased osmolyte uptake was associated with upregulation of mRNA steady-state levels for osmolyte transporters in irradiated cells. These results demonstrate that ultraviolet A radiation leads to the accumulation of compatible organic osmolytes in HLECs as hyperosmotic pressure, which can maintain cellular environmental homeostasis.

  10. Inhibition of insulin fibrillation by osmolytes: Mechanistic Insights

    Science.gov (United States)

    Choudhary, Sinjan; Kishore, Nand; Hosur, Ramakrishna V.

    2015-11-01

    We have studied here using a number of biophysical tools the effects of osmolytes, betaine, citrulline, proline and sorbitol which differ significantly in terms of their physical characteristics such as, charge distribution, polarity, H-bonding abilities etc, on the fibrillation of insulin. Among these, betaine, citrulline, and proline are very effective in decreasing the extent of fibrillation. Proline also causes a substantial delay in the onset of fibrillation in the concentration range (50-250 mM) whereas such an effect is seen for citrulline only at 250 mM, and in case of betaine this effect is not seen at all in the whole concentration range. The enthalpies of interaction at various stages of fibrillation process have suggested that the preferential exclusion of the osmolyte and its polar interaction with the protein are important in inhibition. The results indicate that the osmolytes are most effective when added prior to the elongation stage of fibrillation. These observations have significant biological implications, since insulin fibrillation is known to cause injection amyloidosis and our data may help in designing lead drug molecules and development of potential therapeutic strategies.

  11. Osmolytes contribute to pH homeostasis of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Ryan D Kitko

    Full Text Available BACKGROUND: Cytoplasmic pH homeostasis in Escherichia coli includes numerous mechanisms involving pH-dependent catabolism and ion fluxes. An important contributor is transmembrane K+ flux, but the actual basis of K+ compensation for pH stress remains unclear. Osmoprotection could mediate the pH protection afforded by K+ and other osmolytes. METHODS AND PRINCIPAL FINDINGS: The cytoplasmic pH of E. coli K-12 strains was measured by GFPmut3 fluorimetry. The wild-type strain Frag1 was exposed to rapid external acidification by HCl addition. Recovery of cytoplasmic pH was enhanced equally by supplementation with NaCl, KCl, proline, or sucrose. A triple mutant strain TK2420 defective for the Kdp, Trk and Kup K+ uptake systems requires exogenous K+ for steady-state pH homeostasis and for recovery from sudden acid shift. The K+ requirement however was partly compensated by supplementation with NaCl, choline chloride, proline, or sucrose. Thus, the K+ requirement was mediated in part by osmolarity, possibly by relieving osmotic stress which interacts with pH stress. The rapid addition of KCl to strain TK2420 suspended at external pH 5.6 caused a transient decrease in cytoplasmic pH, followed by slow recovery to an elevated steady-state pH. In the presence of 150 mM KCl, however, rapid addition of another 150 mM KCl caused a transient increase in cytoplasmic pH. These transient effects may arise from secondary K+ fluxes occurring through other transport processes in the TK2420 strain. CONCLUSIONS: Diverse osmolytes including NaCl, KCl, proline, or sucrose contribute to cytoplasmic pH homeostasis in E. coli, and increase the recovery from rapid acid shift. Osmolytes other than K+ restore partial pH homeostasis in a strain deleted for K+ transport.

  12. Retardation of Bulk Water Dynamics by Disaccharide Osmolytes

    CERN Document Server

    Shukla, Nimesh; Chen, Lee; Chergui, Majed; Othon, Christina M

    2016-01-01

    The bioprotective nature of disaccharides is hypothesized to derive from the modification of the hydrogen bonding network of water which protects biomolecules through lowered water activity at the protein interface. Using ultrafast fluorescence spectroscopy we measured the relaxation of bulk water dynamics around the induced dipole moment of two fluorescent probes (Lucifer Yellow Ethylenediamine and Tryptophan). Our results indicate a reduction in bulk water reorganization rate of approximately of 30%. We observe this retardation in the low concentration regime measured at 0.1M and 0.25 M, far below the onset of glassy dynamics. This reduction in water activity could be significant in crowded biological systems, contributing to global change in protein energy landscape, resulting in a significant enhancement of protein stability under environmental stress. We observed similar dynamic reduction for two disaccharide osmolytes, sucrose and trehalose, with trehalose being the more effective dynamic reducer.

  13. Transport kinetics of ectoine, an osmolyte produced by Brevibacterium epidermis.

    Science.gov (United States)

    Onraedt, A; De Mey, M; Walcarius, B; Soetaert, W; Vandamme, E J

    2006-11-01

    Brevibacterium epidermis DSM 20659 is a halotolerant Gram-positive bacterium which can synthesize the osmolyte, ectoine, but prefers to take it up from its environment. The present study revealed that B. epidermis is equipped with at least one transport system for ectoine, with a maximal transport velocity of 15.7 +/- 4.3 nmol/g CDW.min. The transport requires energy (ATP) and is completely inhibited by the proton uncoupler, CCCP. The ectoine uptake system is constitutively expressed at a basal level of activity and its activity is immediately 10-fold increased by hyper-osmotic stress. Initial uptake rates are not influenced by the intensity of the hyper-osmotic shock but the duration of the increased activity of the uptake system could be directly related to the osmotic strength of the assay solution. Competition assays indicate that betaine, but not proline, is also transported by the ectoine uptake system.

  14. Enthalpies of DNA melting in the presence of osmolytes.

    Science.gov (United States)

    Spink, Charles H; Garbett, Nichola; Chaires, Jonathan B

    2007-03-01

    The melting of DNA in the presence of osmolytes has been studied with the intention of obtaining information about how base pair stability is affected by changes in solution conditions. In previous investigations, the melting enthalpies were assumed to be constant as osmolalities change, but no systematic evaluation of whether this condition is true has been offered. This paper presents calorimetric data on the melting of two synthetic DNA samples in the presence of a number of common osmolytes. Poly(dAdT)*poly(dTdA) and poly(dGdC)*poly(dCdG) melting have been examined by differential scanning calorimetry in solutions containing ethylene glycol, glycerol, sucrose, urea, betaine, PEG 200 and PEG 1450 at increasing osmolalities. The results show small, but significant changes in the enthalpy of melting of the two polynucleotides that are different, depending on the structure of the cosolvent. The polyols, ethylene glycol, glycerol, PEG 200 and also urea all show decreases in melting enthalpy, while betaine and sucrose display increases with increasing concentration of cosolvent. The large stabilizing PEG 1450 shows no change within the experimental errors. Using concepts relating to preferential interactions of the cosolvents with the DNA base pairs, it is possible to interpret some of the observed changes in the thermodynamic properties of melting. The results indicate that there is strong entropy-enthalpy compensation upon melting base pairs, but entropy increases dominate to cause the decreases in stability with increased cosolvent concentration. Excess hydration parameters are evaluated and their magnitudes discussed in terms of changes in cosolvent interactions with the DNA base pairs.

  15. Alleviation of salt stress by Halomonas sp. and osmolytes in Zea mays

    African Journals Online (AJOL)

    These strains can favour plant growth due to their endogenous osmolyte ... Seeds were sown in soil supplemented with and without exogenous proline and glycine ... This can be an alternate economic approach to increase crop productivity.

  16. Structural characteristic of the initial unfolded state on refolding determines catalytic efficiency of the folded protein in presence of osmolytes.

    Directory of Open Access Journals (Sweden)

    Marina Warepam

    Full Text Available Osmolytes are low molecular weight organic molecules accumulated by organisms to assist proper protein folding, and to provide protection to the structural integrity of proteins under denaturing stress conditions. It is known that osmolyte-induced protein folding is brought by unfavorable interaction of osmolytes with the denatured/unfolded states. The interaction of osmolyte with the native state does not significantly contribute to the osmolyte-induced protein folding. We have therefore investigated if different denatured states of a protein (generated by different denaturing agents interact differently with the osmolytes to induce protein folding. We observed that osmolyte-assisted refolding of protein obtained from heat-induced denatured state produces native molecules with higher enzyme activity than those initiated from GdmCl- or urea-induced denatured state indicating that the structural property of the initial denatured state during refolding by osmolytes determines the catalytic efficiency of the folded protein molecule. These conclusions have been reached from the systematic measurements of enzymatic kinetic parameters (Km and kcat, thermodynamic stability (Tm and ΔHm and secondary and tertiary structures of the folded native proteins obtained from refolding of various denatured states (due to heat-, urea- and GdmCl-induced denaturation of RNase-A in the presence of various osmolytes.

  17. Growth, osmolyte concentration and antioxidant enzymes in the leaves of Sesuvium portulacastrum L. under salinity stress.

    Science.gov (United States)

    Kannan, P Ramesh; Deepa, S; Kanth, Swarna V; Rengasamy, R

    2013-12-01

    In this study, growth and osmolyte concentration in the leaves of halophyte, Sesuvium portulacastrum, were studied with respect to salinity. Therefore, the changes in shoot growth, leaf tissue water content, osmolyte concentration (proline content, glycine betaine) and antioxidant enzymes [polyphenol oxidase (PPO), superoxide dismutase (SOD) and catalase (CAT)] were investigated. The 30-day old S. portulacastrum plants were subjected to 100, 200, 300, 400, 500 and 600 mM NaCl for 28 days. The plant growth was steadily increased up to 500 mM NaCl stress at 28 days. TWC was higher in 300 mM NaCl treated leaves than that of 600 mM NaCl. Salinity stress induced the accumulation of osmolyte concentration when compared to control during the study period. The antioxidant enzymes PPO, CAT and SOD were increased under salinity.

  18. Insensitivity of volume-sensitive chloride currents to chromones in human airway epithelial cells

    Science.gov (United States)

    Zegarra-Moran, Olga; Lantero, Sabina; Sacco, Oliviero; Rossi, Giovanni A; Galietta, Luis J V

    1998-01-01

    Chromones (sodium cromoglycate and sodium nedocromil) block cell swelling-activated Cl− channels in NIH-3T3 fibroblasts and endothelial cells. This has led to hypothesize that cell volume regulation might be involved in asthma pathogenesis.Using whole-cell patch-clamp experiments, we studied the effect of chromones on volume-sensitive Cl− currents in transformed human tracheal epithelial cells (9HTEo-) and in primary cultures of human bronchial epithelial cells (BE).Cl− currents activated by hypotonic shock were poorly blocked by extracellular nedocromil or cromoglycate. The block was voltage-dependent since it was observed only at positive membrane potentials. At the concentration of 5 mM, the current inhibition by both chromones at +80 mV was about 40% for 9HTEo- and only 20% for BE.Intracellular application of chromones elicited a voltage-independent inhibition in 9HTEo- cells. Under this condition, volume-sensitive Cl− currents were reduced at all membrane potentials (60 and 45% inhibition by 2 mM nedocromil and cromoglycate respectively). In contrast intracellular chromones were ineffective in BE cells.The relative refractoriness to chromones, in contrast with the high sensitivity shown by other Cl− channels, suggests that the epithelial volume-sensitive Cl− channel is not involved in asthma. PMID:9863671

  19. Selective inhibition of aggregation/fibrillation of bovine serum albumin by osmolytes: Mechanistic and energetics insights

    Science.gov (United States)

    Dasgupta, Moumita

    2017-01-01

    Bovine serum albumin (BSA) is an important transport protein of the blood and its aggregation/fibrillation would adversely affect its transport ability leading to metabolic disorder. Therefore, understanding the mechanism of fibrillation/aggregation of BSA and design of suitable inhibitor molecules for stabilizing its native conformation, are of utmost importance. The qualitative and quantitative aspects of the effect of osmolytes (proline, hydroxyproline, glycine betaine, sarcosine and sorbitol) on heat induced aggregation/fibrillation of BSA at physiological pH (pH 7.4) have been studied employing a combination of fluorescence spectroscopy, Rayleigh scattering, isothermal titration calorimetry (ITC), dynamic light scattering (DLS) and transmission electron microscopy (TEM). Formation of fibrils by BSA under the given conditions was confirmed from increase in fluorescence emission intensities of Thioflavin T over a time period of 600 minutes and TEM images. Absence of change in fluorescence emission intensities of 8-Anilinonaphthalene-1-sulfonic acid (ANS) in presence of native and aggregated BSA signify the absence of any amorphous aggregates. ITC results have provided important insights on the energetics of interaction of these osmolytes with different stages of the fibrillar aggregates of BSA, thereby suggesting the possible modes/mechanism of inhibition of BSA fibrillation by these osmolytes. The heats of interaction of the osmolytes with different stages of fibrillation of BSA do not follow a trend, suggesting that the interactions of stages of BSA aggregates are osmolyte specific. Among the osmolytes used here, we found glycine betaine to be supporting and promoting the aggregation process while hydroxyproline to be maximally efficient in suppressing the fibrillation process of BSA, followed by sorbitol, sarcosine and proline in the following order of their decreasing potency: Hydroxyproline> Sorbitol> Sarcosine> Proline> Glycine betaine. PMID:28207877

  20. Betaines and dimethylsulfoniopropionate as major osmolytes in cnidaria with endosymbiotic dinoflagellates.

    Science.gov (United States)

    Yancey, Paul H; Heppenstall, Marina; Ly, Steven; Andrell, Raymond M; Gates, Ruth D; Carter, Virginia L; Hagedorn, Mary

    2010-01-01

    Most marine invertebrates and algae are osmoconformers whose cells accumulate organic osmolytes that provide half or more of cellular osmotic pressure. These solutes are primarily free amino acids and glycine betaine in most invertebrates and small carbohydrates and dimethylsulfoniopropionate (DMSP) in many algae. Corals with endosymbiotic dinoflagellates (Symbiodinium spp.) have been reported to obtain from the symbionts potential organic osmolytes such as glycerol, amino acids, and DMSP. However, corals and their endosymbionts have not been fully analyzed for osmolytes. We quantified small carbohydrates, free amino acids, methylamines, and DMSP in tissues of the corals Fungia scutaria, Pocillopora damicornis, Pocillopora meandrina, Montipora capitata, Porites compressa, and Porites lobata (all with symbionts) plus Tubastrea aurea (asymbiotic) from Kaneohe Bay, Oahu (Hawaii). Glycine betaine, at 33-69 mmol/kg wet mass, was found to constitute 90% or more of the measured organic solutes in all except the Porites species. Those were dominated by proline betaine and dimethyltaurine. DMSP was found at 0.5-3 mmol/kg in all species with endosymbionts. Freshly isolated Symbiodinium from Fungia, P. damicornis, and P. compressa were also analyzed. DMSP and glycine betaine dominated in the first two; Porites endosymbionts had DMSP, proline betaine, and dimethyltaurine. In all specimens, glycerol and glucose were detected by high-performance liquid chromatography only at 0-1 mmol/kg wet mass. An enzymatic assay for glycerol plus glycerol 3-phosphate and dihydroxyacetone phosphate yielded 1-10 mmol/kg. Cassiopeia andromeda (upside-down jelly; Scyphozoan) and Aiptasia puchella (solitary anemone; Anthozoan) were also analyzed; both have endosymbiotic dinoflagellates. In both, glycine betaine, taurine, and DMSP were the dominant osmolytes. In summary, methylated osmolytes dominate in many Cnidaria; in those with algal symbionts, host and symbiont have similar methylated amino

  1. Natural osmolytes remodel the aggregation pathway of mutant huntingtin exon 1.

    Science.gov (United States)

    Borwankar, Tejas; Röthlein, Christoph; Zhang, Gong; Techen, Anne; Dosche, Carsten; Ignatova, Zoya

    2011-03-29

    In response to stress small organic compounds termed osmolytes are ubiquitously accumulated in all cell types to regulate the intracellular solvent quality and to counteract the deleterious effect on the stability and function of cellular proteins. Given the evidence that destabilization of the native state of a protein either by mutation or by environmental changes triggers the aggregation in the neurodegenerative pathologies, the modulation of the intracellular solute composition with osmolytes is an attractive strategy to stabilize an aggregating protein. Here we report the effect of three natural osmolytes on the in vivo and in vitro aggregation landscape of huntingtin exon 1 implicated in the Huntington's disease. Trimethylamine N-oxide (TMAO) and proline redirect amyloid fibrillogenesis of the pathological huntingtin exon 1 to nonamyloidogenic amorphous assemblies via two dissimilar molecular mechanisms. TMAO causes a rapid formation of bulky amorphous aggregates with minimally exposed surface area, whereas proline solubilizes the monomer and suppresses the accumulation of early transient aggregates. Conversely, glycine-betaine enhances fibrillization in a fashion reminiscent of the genesis of functional amyloids. Strikingly, none of the natural osmolytes can completely abrogate the aggregate formation; however, they redirect the amyloidogenesis into alternative, nontoxic aggregate species. Our study reveals new insights into the complex interactions of osmoprotectants with polyQ aggregates.

  2. The effect of some osmolytes on the activity and stability of mushroom tyrosinase

    Indian Academy of Sciences (India)

    N Gheibi; A A Saboury; K Haghbeen; A A Moosavi-Movahedi

    2006-09-01

    The thermodynamical stability and remained activity of mushroom tyrosinase (MT) from Agaricus bisporus in 10 mM phosphate buffer, pH 6.8, stored at two temperatures of 4 and 40°C were investigated in the presence of three different amino acids (His, Phe and Asp) and also trehalose as osmolytes, for comparing with the results obtained in the absence of any additive. Kinetics of inactivation obeye the first order law. Inactivation rate constant (kinact) value is the best parameter describing effect of osmolytes on kinetic stability of the enzyme. Trehalose and His have the smallest value of kinact (0.7×10–4 s–1) in comparison with their absence (2.5×10–4 s–1). Moreover, to obtain effect of these four osmolytes on thermodynamical stability of the enzyme, protein denaturation by dodecyl trimethylammonium bromide (DTAB) and thermal scanning was investigated. Sigmoidal denaturation curves were analysed according to the two states model of Pace theory to find the Gibbs free energy change of denaturation process in aqueous solution at room temperature, as a very good thermodynamic criterion indicating stability of the protein. Although His, Phe and Asp induced constriction of MT tertiary structure, its secondary structure had not any change and the result was a chemical and thermal stabilization of MT. The enzyme shows a proper coincidence of thermodyanamic and structural changes with the presence of trehalose. Thus, among the four osmolytes, trehalose is an exceptional protein stabilizer.

  3. The effect of some osmolytes on the activity and stability of mushroom tyrosinase.

    Science.gov (United States)

    Gheibi, N; Saboury, A A; Haghbeen, K; Moosavi-Movahedi, A A

    2006-09-01

    The thermodynamical stability and remained activity of mushroom tyrosinase (MT) from Agaricus bisporus in 10 mM phosphate buffer, pH 6.8, stored at two temperatures of 4 and 40 degrees C were investigated in the presence of three different amino acids (His, Phe and Asp) and also trehalose as osmolytes, for comparing with the results obtained in the absence of any additive. Kinetics of inactivation obey the first order law. Inactivation rate constant (kinact) value is the best parameter describing effect of osmolytes on kinetic stability of the enzyme. Trehalose and His have the smallest value of kinact (0.7x10(-4) s-1) in comparison with their absence (2.5x10(-4) s-1). Moreover, to obtain effect of these four osmolytes on thermodynamical stability of the enzyme, protein denaturation by dodecyl trimethylammonium bromide (DTAB) and thermal scanning was investigated. Sigmoidal denaturation curves were analysed according to the two states model of Pace theory to find the Gibbs free energy change of denaturation process in aqueous solution at room temperature, as a very good thermodynamic criterion indicating stability of the protein. Although His, Phe and Asp induced constriction of MT tertiary structure, its secondary structure had not any change and the result was a chemical and thermal stabilization of MT. The enzyme shows a proper coincidence of thermodynamic and structural changes with the presence of trehalose. Thus, among the four osmolytes, trehalose is an exceptional protein stabilizer.

  4. Effect of osmolytes on protein dynamics in the lactate dehydrogenase-catalyzed reaction.

    Science.gov (United States)

    Zhadin, Nickolay; Callender, Robert

    2011-03-15

    Laser-induced temperature jump relaxation spectroscopy was used to probe the effect of osmolytes on the microscopic rate constants of the lactate dehydrogenase-catalyzed reaction. NADH fluorescence and absorption relaxation kinetics were measured for the lactate dehydrogenase (LDH) reaction system in the presence of varying amounts of trimethylamine N-oxide (TMAO), a protein-stabilizing osmolyte, or urea, a protein-destabilizing osmolyte. Trimethylamine N-oxide (TMAO) at a concentration of 1 M strongly increases the rate of hydride transfer, nearly nullifies its activation energy, and also slightly increases the enthalpy of hydride transfer. In 1 M urea, the hydride transfer enthalpy is almost nullified, but the activation energy of the step is not affected significantly. TMAO increases the preference of the closed conformation of the active site loop in the LDH·NAD(+)·lactate complex; urea decreases it. The loop opening rate in the LDH·NADH·pyruvate complex changes its temperature dependence to inverse Arrhenius with TMAO. In this complex, urea accelerates the loop motion, without changing the loop opening enthalpy. A strong, non-Arrhenius decrease in the pyruvate binding rate in the presence of TMAO offers a decrease in the fraction of the open loop, pyruvate binding competent form at higher temperatures. The pyruvate off rate is not affected by urea but decreases with TMAO. Thus, the osmolytes strongly affect the rates and thermodynamics of specific events along the LDH-catalyzed reaction: binding of substrates, loop closure, and the chemical event. Qualitatively, these results can be understood as an osmolyte-induced change in the energy landscape of the protein complexes, shifting the conformational nature of functional substates within the protein ensemble.

  5. Quantifying additive interactions of the osmolyte proline with individual functional groups of proteins: comparisons with urea and glycine betaine, interpretation of m-values.

    Science.gov (United States)

    Diehl, Roger C; Guinn, Emily J; Capp, Michael W; Tsodikov, Oleg V; Record, M Thomas

    2013-09-03

    To quantify interactions of the osmolyte l-proline with protein functional groups and predict their effects on protein processes, we use vapor pressure osmometry to determine chemical potential derivatives dμ2/dm3 = μ23, quantifying the preferential interactions of proline (component 3) with 21 solutes (component 2) selected to display different combinations of aliphatic or aromatic C, amide, carboxylate, phosphate or hydroxyl O, and amide or cationic N surface. Solubility data yield μ23 values for four less-soluble solutes. Values of μ23 are dissected using an ASA-based analysis to test the hypothesis of additivity and obtain α-values (proline interaction potentials) for these eight surface types and three inorganic ions. Values of μ23 predicted from these α-values agree with the experiment, demonstrating additivity. Molecular interpretation of α-values using the solute partitioning model yields partition coefficients (Kp) quantifying the local accumulation or exclusion of proline in the hydration water of each functional group. Interactions of proline with native protein surfaces and effects of proline on protein unfolding are predicted from α-values and ASA information and compared with experimental data, with results for glycine betaine and urea, and with predictions from transfer free energy analysis. We conclude that proline stabilizes proteins because of its unfavorable interactions with (exclusion from) amide oxygens and aliphatic hydrocarbon surfaces exposed in unfolding and that proline is an effective in vivo osmolyte because of the osmolality increase resulting from its unfavorable interactions with anionic (carboxylate and phosphate) and amide oxygens and aliphatic hydrocarbon groups on the surface of cytoplasmic proteins and nucleic acids.

  6. Data on the role of accessible surface area on osmolytes-induced protein stabilization

    Directory of Open Access Journals (Sweden)

    Safikur Rahman

    2017-02-01

    Full Text Available This paper describes data related to the research article “Testing the dependence of stabilizing effect of osmolytes on the fractional increase in the accessible surface area on thermal and chemical denaturations of proteins” [1]. Heat- and guanidinium chloride (GdmCl-induced denaturation of three disulfide free proteins (bovine cytochrome c (b-cyt-c, myoglobin (Mb and barstar in the presence of different concentrations of methylamines (sarcosine, glycine-betaine (GB and trimethylamine-N-oxide (TMAO was monitored by [ϴ]222, the mean residue ellipticity at 222 nm at pH 7.0. Methylamines belong to a class of osmolytes known to protect proteins from deleterious effect of urea. This paper includes comprehensive thermodynamic data obtained from the heat- and GdmCl-induced denaturations of barstar, b-cyt-c and Mb.

  7. Regulatory Factors Associated with Synthesis of the Osmolyte Glycine Betaine in the Halophilic Methanoarchaeon Methanohalophilus portucalensis

    OpenAIRE

    Lai, Mei-Chin; Yang, Daw-Renn; Chuang, Ming-Jen

    1999-01-01

    The halophilic methanoarchaeon Methanohalophilus portucalensis can synthesize de novo and accumulate β-glutamine, Nɛ-acetyl-β-lysine, and glycine betaine (betaine) as compatible solutes (osmolytes) when grown at elevated salt concentrations. Both in vivo and in vitro betaine formation assays in this study confirmed previous nuclear magnetic resonance 13C-labelling studies showing that the de novo synthesis of betaine proceeded from glycine, sarcosine, and dimethylglycine to form betaine throu...

  8. Effects of a naturally occurring compatible osmolyte on the internal dynamics of ribonuclease A.

    Science.gov (United States)

    Wang, A; Robertson, A D; Bolen, D W

    1995-11-21

    Osmolytes are small organic solutes accumulated intracellularly by many organisms as they adapt to environmental stresses. Compatible osmolytes, a functional class of osmolytes, increase protein stability while having little or no effect on protein function. To investigate the interrelationships between protein stability, function, and internal dynamics, a hydrogen exchange (HX) quench method was established and used to study the effects of sucrose (a typical compatible osmolyte) on the structural fluctuations of ribonuclease A. It was found that the HX rates of the amide protons with intermediate rates are not affected by 1 M sucrose, but the slow-exchanging amide protons exchange even slower in 1 M sucrose. The protection factors of the slow-exchanging protons fall into a comparatively narrow range while those of the intermediate-exchanging protons vary widely. In agreement with the two-process model [Woodward, C.K., & Hilton, B. D. (1980) Biophys. J. 32, 561-575], we conclude that for those slow-exchanging amide protons, the exchange occurs mainly from the compact unfolded state ensemble of the protein. The internal dynamics leading to slow exchange involve exposure of large protein surface areas, similar to that which occurs upon the unfolding of protein. Because sucrose opposes such an increase in protein surface area exposure, both the slow HX rates and the protein stability are affected by sucrose. For those amide protons with fast and intermediate HX rates, the exchange occurs mainly from the native state ensemble of the protein. The internal dynamics involved in the exchange are localized without much surface area change, and functionally important structural fluctuations are likely to occur within this dynamic range.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Growth phase-dependent switch in osmolyte strategy in a moderate halophile: ectoine is a minor osmolyte but major stationary phase solute in Halobacillus halophilus.

    Science.gov (United States)

    Saum, Stephan H; Müller, Volker

    2008-03-01

    The moderately halophilic, chloride-dependent bacterium Halobacillus halophilus switches its osmolyte strategy with the salinity in its environment by the production of different compatible solutes. Ectoine is produced predominantly at very high salinities, along with proline. Interestingly, ectoine production is growth phase dependent which led to a more than 1000-fold change in the ectoine : proline ratio from 0.04 in exponential to 27.4 in late stationary phase cultures. The genes encoding the ectoine biosynthesis pathway were identified on the chromosome in the order ectABC. They form an operon that is expressed in a salinity-dependent manner with low-level expression below 1.5 M NaCl but 10-fold and 23-fold increased expression at 2.5 and 3.0 M NaCl respectively. The temporal expression of genes involved in osmoresponse is different with gdh/gln and pro genes being first, followed by ect genes. Chloride had no effect on expression of ect genes, but stimulated cellular EctC synthesis as well as ectoine production. These data demonstrate, for the first time, a growth-phase dependent switch in osmolyte strategy in a moderate halophile and, additionally, represent another piece of the chloride regulon of H. halophilus.

  10. How osmolytes influence hydrophobic polymer conformations: A unified view from experiment and theory.

    Science.gov (United States)

    Mondal, Jagannath; Halverson, Duncan; Li, Isaac T S; Stirnemann, Guillaume; Walker, Gilbert C; Berne, Bruce J

    2015-07-28

    It is currently the consensus belief that protective osmolytes such as trimethylamine N-oxide (TMAO) favor protein folding by being excluded from the vicinity of a protein, whereas denaturing osmolytes such as urea lead to protein unfolding by strongly binding to the surface. Despite there being consensus on how TMAO and urea affect proteins as a whole, very little is known as to their effects on the individual mechanisms responsible for protein structure formation, especially hydrophobic association. In the present study, we use single-molecule atomic force microscopy and molecular dynamics simulations to investigate the effects of TMAO and urea on the unfolding of the hydrophobic homopolymer polystyrene. Incorporated with interfacial energy measurements, our results show that TMAO and urea act on polystyrene as a protectant and a denaturant, respectively, while complying with Tanford-Wyman preferential binding theory. We provide a molecular explanation suggesting that TMAO molecules have a greater thermodynamic binding affinity with the collapsed conformation of polystyrene than with the extended conformation, while the reverse is true for urea molecules. Results presented here from both experiment and simulation are in line with earlier predictions on a model Lennard-Jones polymer while also demonstrating the distinction in the mechanism of osmolyte action between protein and hydrophobic polymer. This marks, to our knowledge, the first experimental observation of TMAO-induced hydrophobic collapse in a ternary aqueous system.

  11. Effects of the osmolyte TMAO (Trimethylamine-N-oxide) on aqueous hydrophobic contact-pair interactions.

    Science.gov (United States)

    Macdonald, Ryan D; Khajehpour, Mazdak

    2013-12-31

    Osmolytes are small, soluble organic molecules produced by living organisms for maintaining cell volume. These molecules have also been shown to have significant effects on the stability of proteins. Perhaps one of the most studied osmolytes is Trimethylamine-N-oxide (TMAO). Thermodynamic studies of the effects of TMAO on proteins have shown that this molecule is a strong stabilizer of the protein folded state, thus being able to counteract the effects of protein denaturants such as urea and guanidine hydrochloride. Most studies of TMAO effects on bio-molecular stability have until now been focused on how the osmolyte reduces the solubility of polypeptide backbones, while the effects of TMAO on hydrophobic interactions are still not well understood. In fact, there are few experimental data measuring the effect of TMAO on hydrophobic interactions. This work studies phenyl and alkyl contact pairs as model hydrophobic contact pairs. The formation of these contact pairs is monitored using fluorescence, i.e., through the quenching of phenol fluorescence by carboxylate ions; and a methodology is developed to isolate hydrophobic contributions from other interactions. The data demonstrate that the addition of TMAO to the aqueous solvent destabilizes hydrophobic contact pairs formed between alkyl and phenyl moieties. In other words, TMAO acts as a "denaturant" for hydrophobic interactions.

  12. The Influence of Osmolytes on the Antimicrobial Activity of Silver Nanoparticles

    Science.gov (United States)

    Reed-Jones, Neiunna L.

    Silver nanoparticles (Ag-NPs) are gaining popularity as antimicrobial agents due to their broad- spectrum activity and lower propensity to develop resistance in bacteria. However, with increased frequency of use, there remains a possibility for bacteria to develop resistance or adaptive mechanisms against Ag-NPs overtime. Mechanisms used by bacteria to resist antimicrobial agents include efflux pumps, heat shock proteins (Hsp) and accumulation of compatible solutes, generally referred to as osmolytes. The latter mechanism is typically employed when bacteria are under osmotic stress they accumulate osmolytes either through de novo synthesis or exogenously. Osmolytes act to stabilize the bacterial cell membrane by maintaining the native protein structure, while at the same time, ensuring compatibility with other cellular structures and functions. The most common osmolytes accumulated by bacteria are glycine betaine, proline, carnitine, choline, trehalose and glutamate. Since Ag-NPs target the cell membrane it is conceivable that osmolytes may suppress its bactericidal activity. In the present study, we assess the antimicrobial efficacy of Ag-NPs in the presence of glycine betaine and proline. Exponential phase cultures (106 cfu/ml) of Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus were exposed to a predetermined the minimum inhibitory concentration (MIC) of 0.4 mM of citrate-stabilized Ag-NPs and incubated at 37°C for 48 h. This was replicated with the addition of 1 mM of either glycine betaine or proline. Growth was monitored by optical density, standard plate count, resazurin assay and LIVE/DEAD analyses. The result showed that Ag-NPs had no detectable effect on osmolyte treated cells. The average plate count of cultures supplemented with either glycine betaine or proline ranged from 108 to 109 cfu/ml after 48 h. Resazurin assay also showed that there was a significant increase in the cells supplemented with

  13. Mechanistic insights into osmolyte action in protein stabilization under harsh conditions: N-methylacetamide in glycine betaine-urea mixture

    Science.gov (United States)

    Kumar, Narendra; Kishore, Nand

    2014-10-01

    Glycine betaine (GB), a small naturally occurring osmolyte, stabilizes proteins and counteracts harsh denaturing conditions such as extremes of temperature, cellular dehydration, and presence of high concentration of urea. In spite of several studies on understanding mechanism of protein stabilization and counteraction of these harsh conditions by osmolytes, studies centred on GB, one of the most important osmolyte, are scarce, hence, there is need for more investigations. To explore mechanism of protein stabilization and counteraction of denaturing property of urea by GB, molecular dynamics studies of N-methylacetamide (NMA), a model peptide representing denatured state of a protein, in the presence of GB, urea, and GB-urea mixture were carried out. The results show that GB and urea work such that the strength of GB as a protecting osmolyte is increased and the denaturing ability of urea is decreased in the GB-urea mixture. It can be inferred that GB counteracts urea by decreasing its hydrophobic interactions with proteins. The mutual interactions between GB and urea also play an important role in protein stabilization. This study provides insights on osmolyte induced counteraction of denaturing property of urea.

  14. Natural osmolytes alleviate GRP78 and ATF-4 levels: Corroboration for potential modulators of unfolded protein response.

    Science.gov (United States)

    Hazari, Younis Mohammad; Habib, Mudasir; Bashir, Samirul; Bashir, Arif; Hilal, Nazia; Irfan, Sheikh; Ul Haq, Ehtisham; Fazili, Khalid Majid

    2016-02-01

    Osmolytes are small organic molecules which play a significant role in maintaining functional homeostasis of proteins under extreme hostile stresses. Any imbalance to cell homeostasis leads to Endoplasmic Reticulum stress (ER-stress) to which a set of cellular responses both at transcriptional and translational level are initialed for restoration of cellular homeostasis called Unfolded Protein Response (UPR). In the present study we evaluated the role of Sarcosine, Betaine, Hydroxyectoine and Ectoine as potential modulators of UPR. ER-stress was induced by Tunicamycin, a prototypic experimental ER-stress inducer. The endogenous cellular levels of UPR markers Glucose-Regulated Protein 78 (GRP78) and Activating Transcription Factor-4 (ATF-4) were evaluated in presence and absence of these osmolytes after inducing UPR with tunicamycin. As a prelude to this, IC50 values of these osmolytes were determined by using cell viability assays like MTT and Trypan Blue exclusion assay. We found that these osmolytes in a dose-dependent manner increased the rate of restoration of homeostasis as was evident by the decreased endogenous levels of GRP78 and ATF-4. These natural osmolytes can thus be useful in therapeutic intervention to mitigate the pathophysiological state resulting from ER-stress. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. [Effects of drought stress and nitrogen fertilization rate on the accumulation of osmolytes in Jatropha curcas seedlings].

    Science.gov (United States)

    Yin, Li; Liu, Yong-An; Xie, Cai-Yong; Jiang, Xue; Wang, Yong-Jie; Li, Yin-Hua; Yan, Zhen; Hu, Ting-Xing

    2012-03-01

    A pot experiment with controlled water supply was conducted to study the effects of different drought stress degree (80% FC, 60% FC, 40% FC, and 20% FC) and nitrogen fertilization rate (0 g x pot(-1), 1.2 g x pot(-1), 3.6 g x pot(-1), and 6.0 g x pot(-1)) on the accumulation of osmolytes in different organs of Jatropha curcas seedlings. Under drought stress, the soluble protei and free proline in seedling shoots and roots and the soluble sugar in seedling shoots had a great accumulation, and the free proline content in seedling leaves had a great increase with increasing drought stress degree. Also under drought stress, the Na+, Ca2+, and Mg2+ all highly accumulated in seedling various organs, while K only accumulated greatly in shoots but slightly in leaves and roots. The effects of nitrogen fertilization on the accumulation of osmolytes in seedlings depended on drought stress degree and nitrogen fertilization rate. At 80% FC and 60% FC, increasing nitrogen fertilization rate could markedly promote the accumulation of osmolytes in the organs of J. curcas seedlings; at 40% FC, applying 6.0 g x pot(-1) weakened the promotion effect on the osmolytes accumulation; whereas at 20%, applying 1.2 g x pot(-1) made the plants have a higher capability in osmoregulation, but applying 3.6 g x pot(-1) and 6.0 g x pot(-1) had less promotion effect, and even, inhibited osmolytes accumulation.

  16. Nitric Oxide Mitigates Salt Stress by Regulating Levels of Osmolytes and Antioxidant Enzymes in Chickpea

    Science.gov (United States)

    Ahmad, Parvaiz; Abdel Latef, Arafat A.; Hashem, Abeer; Abd_Allah, Elsayed F.; Gucel, Salih; Tran, Lam-Son P.

    2016-01-01

    This work was designed to evaluate whether external application of nitric oxide (NO) in the form of its donor S-nitroso-N-acetylpenicillamine (SNAP) could mitigate the deleterious effects of NaCl stress on chickpea (Cicer arietinum L.) plants. SNAP (50 μM) was applied to chickpea plants grown under non-saline and saline conditions (50 and 100 mM NaCl). Salt stress inhibited growth and biomass yield, leaf relative water content (LRWC) and chlorophyll content of chickpea plants. High salinity increased electrolyte leakage, carotenoid content and the levels of osmolytes (proline, glycine betaine, soluble proteins and soluble sugars), hydrogen peroxide (H2O2) and malondialdehyde (MDA), as well as the activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase in chickpea plants. Expression of the representative SOD, CAT and APX genes examined was also up-regulated in chickpea plants by salt stress. On the other hand, exogenous application of NO to salinized plants enhanced the growth parameters, LRWC, photosynthetic pigment production and levels of osmolytes, as well as the activities of examined antioxidant enzymes which is correlated with up-regulation of the examined SOD, CAT and APX genes, in comparison with plants treated with NaCl only. Furthermore, electrolyte leakage, H2O2 and MDA contents showed decline in salt-stressed plants supplemented with NO as compared with those in NaCl-treated plants alone. Thus, the exogenous application of NO protected chickpea plants against salt stress-induced oxidative damage by enhancing the biosyntheses of antioxidant enzymes, thereby improving plant growth under saline stress. Taken together, our results demonstrate that NO has capability to mitigate the adverse effects of high salinity on chickpea plants by improving LRWC, photosynthetic pigment biosyntheses, osmolyte accumulation and antioxidative defense system. PMID:27066020

  17. Nitric oxide mitigates salt stress by regulating levels of osmolytes and antioxidant enzymes in chickpea

    Directory of Open Access Journals (Sweden)

    Parvaiz eAhmad

    2016-03-01

    Full Text Available This work was designed to evaluate whether external application of nitric oxide (NO in the form of its donor S-nitroso-N-acetylpenicillamine (SNAP could mitigate the deleterious effects of NaCl stress on chickpea (Cicer arietinum L. plants. SNAP (50 μM was applied to chickpea plants grown under non-saline and saline conditions (50 and 100 mM NaCl. Salt stress negatively affected growth and biomass yield, leaf relative water content (LRWC and chlorophyll content of chickpea plants. High salinity increased electrolyte leakage, carotenoid content and the levels of osmolytes (proline, glycine betaine, soluble proteins and soluble sugars, hydrogen peroxide (H2O2 and malondialdehyde (MDA, as well as the activities of antioxidant enzymes, such as superoxide dismutase (SOD, catalase (CAT, ascorbate peroxidase (APX, and glutathione reductase (GR in chickpea plants. Expression of the representative SOD, CAT and APX genes examined was also up-regulated in chickpea plants by salt stress. On the other hand, exogenous application of NO to salinized plants enhanced the growth parameters, LRWC, photosynthetic pigment production and levels of osmolytes, as well as the activities of examined antioxidant enzymes which is correlated with up-regulation of the examined SOD, CAT and APX genes, in comparison with plants treated with NaCl only. Furthermore, electrolyte leakage, H2O2 and MDA contents showed decline in salt-stressed plants supplemented with NO as compared with those in NaCl-treated plants alone. Thus, the exogenous application of NO protected chickpea plants against salt-induced oxidative damage by enhancing the biosynthesis of antioxidant enzymes, thereby improving plant growth under saline stress. Taken together, our results demonstrate that NO has capability to mitigate the adverse effects of high salinity on chickpea plants by improving LRWC, photosynthetic pigment biosyntheses, osmolyte accumulation and antioxidative defense system.

  18. Anion exchange membrane

    Science.gov (United States)

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

    2013-05-07

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

  19. Anions in Cometary Comae

    Science.gov (United States)

    Charnley, Steven B.

    2011-01-01

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

  20. Elevated osmolytes in rainbow smelt: the effects of urea, glycerol and trimethylamine oxide on muscle contractile properties.

    Science.gov (United States)

    Coughlin, David J; Long, Gabrielle M; Gezzi, Nicole L; Modi, Parth M; Woluko, Kossivi N

    2016-04-01

    Rainbow smelt, Osmerus mordax, experience a wide range of temperatures in their native habitat. In response to cold, smelt express anti-freeze proteins and the osmolytes glycerol, trimethylamine N-oxide (TMAO) and urea to avoid freezing. The physiological influences of these osmolytes are not well understood. Urea destabilizes proteins, while TMAO counteracts the protein-destabilizing forces of urea. The influence of glycerol on muscle function has not been explored. We examined the effects of urea, glycerol and TMAO through muscle mechanics experiments with treatments of the three osmolytes at physiological concentrations. Experiments were carried out at 10°C. The contractile properties of fast-twitch muscle bundles were determined in physiological saline and in the presence of 50 mmol l(-1)urea, 50 mmol l(-1)TMAO and/or 200 mmol l(-1)glycerol in saline. Muscle exposed to urea and glycerol produced less force and displayed slower contractile properties. However, treatment with TMAO led to higher force and faster relaxation by muscle bundles. TMAO increased power production during cyclical activity, while urea and glycerol led to reduced oscillatory power output. When muscle bundles were exposed to a combination of the three osmolytes, they displayed little change in contraction kinetics relative to control, although power output under lower oscillatory conditions was enhanced while maximum power output was reduced. The results suggest that maintenance of muscle function in winter smelt requires a balanced combination of urea, glycerol and TMAO.

  1. PLA2 - a major regulator of volume-sensitive taurine release in NIH3T3 fibroblasts

    DEFF Research Database (Denmark)

    Lambert, I. H.

    2006-01-01

    Release of the organic osmolyte taurine efflux from NIH3T3 cells is increased by osmotic cell swelling in hypotonic medium and decreased by osmotic cell shrinkage in hypertonic medium. Release of arachidonic acid is increased under hypotonic conditions if oxidation of the fatty acid via the 5...... and taurine in NIH3T3 cells under isotonic conditions. The potentiating effect of melittin on arachidonic release and taurine efflux is substantially increased in osmotically swollen cells and almost abolished in osmotic shrunken cells. H2O2 potentiates the melittin-induced taurine efflux under isotonic...... conditions but has only a minor effect on the melittin-induced taurine efflux under hypertonic conditions. Bromoenol lactone and manoalide, known inhibitors of Ca2+-independent phospholipase A2 (iPLA2) and secretory phospholipase A2 (sPLA2), respectively, reduce arachidonic acid and taurine release from NIH3...

  2. Stabilization of yeast hexokinase A by polyol osmolytes: correlation with the physicochemical properties of aqueous solutions.

    Science.gov (United States)

    Tiwari, Ashutosh; Bhat, Rajiv

    2006-11-20

    Osmolytes of the polyol series are known to accumulate in biological systems under stress and stabilize the structures of a wide variety of proteins. While increased surface tension of aqueous solutions has been considered an important factor in protein stabilization effect, glycerol is an exception, lowering the surface tension of water. To clarify this anomalous effect, the effect of a series of polyols on the thermal stability of a highly thermolabile two domain protein yeast hexokinase A has been investigated by differential scanning calorimetry and by monitoring loss in the biological activity of the enzyme as a function of time. A larger increase in the T(m) of domain 1 compared with that of domain 2, varying linearly with the number of hydroxyl groups in polyols, has been observed, sorbitol being the best stabilizer against both thermal as well as urea denaturation. Polyols help retain the activity of the enzyme considerably and a good correlation of the increase in T(m) (DeltaT(m)) and the retention of activity with the increase in the surface tension of polyol solutions, except glycerol, which breaks this trend, has been observed. However, the DeltaT(m) values show a linear correlation with apparent molal heat capacity and volume of aqueous polyol solutions including glycerol. These results suggest that while bulk solution properties contribute significantly to protein stabilization, interfacial properties are not always a good indicator of the stabilizing effect. A subtle balance of various weak binding and exclusion effects of the osmolytes mediated by water further regulates the stabilizing effect. Understanding these aspects is critical in the rational design of stable protein formulations.

  3. A preliminary study of the effect of DBD plasma and osmolytes on T98G brain cancer and HEK non-malignant cells.

    Science.gov (United States)

    Kaushik, Nagendra Kumar; Attri, Pankaj; Kaushik, Neha; Choi, Eun Ha

    2013-04-25

    Non-thermal plasmas are emerging as a novel tool for the treatment of living tissues for biological and medical purpose. In this study, we described the effect of 4 min dielectric barrier discharge (DBD) plasma on both T98G cancer and HEK normal cell lines in the presence of different concentrations of osmolytes. This treatment strategy shows a specific inhibitory effect of a 240 s plasma exposure in the presence of osmolytes against T98G brain cancer cells only, but not on HEK normal cells. Based on these interesting properties of osmolytes, a non-thermal plasma appears to be a potential anticancer treatment strategy for different kinds of cancers in the presence of osmolytes.

  4. The research progress of volume-sensitive Cl- channel in tumor%容积敏感性氯离子通道在肿瘤中的研究进展

    Institute of Scientific and Technical Information of China (English)

    闵先军; 王军; 李辉

    2010-01-01

    细胞肿胀后可以激活或上调一系列阴离子通道,在这些容积激活或调节的阴离子通道中,容积敏感性外向整流(VSOR)氯离子通道的激活和表达最显著和常见.先前研究表明,VSOR在肿瘤细胞的容积调节、细胞增殖、分化、迁移、凋亡和耐药等病理生理过程中发挥重要作用,研究还发现许多信号分子参与了VSOR氯离子通道活性的调节,但其分子定位和激活机制尚不清楚.因此,明确其分子定位和激活机制可能会使VSOR氯离子通道成为肿瘤治疗的新靶点.%Cell swelling activates or upregulates a number of anion channels. Of the volume-activated or-regulated anion channels, the volume-sensitive outwardly rectifying anion channel (VSOR) is most prominently activated and ubiquitously expressed. Volume regulated chloride channels play significant roles in a variety of physiological processes including volume regulation, proliferation, differentiation, migration,apoptosis and resistance of tumor cells. Molecular identification and activation mechanisms of VSOR are poorly understood. Many signaling molecules have been shown to regulate VSOR activity in research, playing permissive or modulatory roles. Therefore, VSOR may be a new anticancer target by identifying its signaling molecules and activation mechanisms.

  5. Slr1670 from Synechocystis sp. PCC 6803 is required for the re-assimilation of the osmolyte glucosylglycerol

    Directory of Open Access Journals (Sweden)

    Philipp Savakis

    2016-08-01

    Full Text Available When subjected to mild salt stress, the cyanobacterium Synechocystis sp. PCC 6803 produces small amounts of glycerol through an as of yet unidentified pathway. Here, we show that this glycerol is a degradation product of the main osmolyte of this organism, glucosylglycerol (GG. Inactivation of ggpS, encoding the first step of GG-synthesis, abolished de novo synthesis of glycerol, while the ability to hydrolyze exogenously supplied glucoslylglycerol was unimpaired. Inactivation of glpK, encoding glycerol kinase, had no effect on glycerol synthesis. Inactivation of slr1670, encoding a GHL5-type putative glycoside hydrolase, abolished de novo synthesis of glycerol, as well as hydrolysis of GG, and led to increased intracellular concentrations of this osmolyte. Slr1670 therefore presumably displays GG hydrolase activity. A gene homologous to the one encoded by slr1670 occurs in a wide range of cyanobacteria, proteobacteria and archaea. In cyanobacteria, it co-occurs with genes involved in GG-synthesis.

  6. Fabrication Localized Surface Plasmon Resonance sensor chip of gold nanoparticles and detection lipase–osmolytes interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ghodselahi, T., E-mail: t_ghodselahi@yahoo.com [Nano Mabna Iranian Inc., PO Box 1676664116, Tehran (Iran, Islamic Republic of); School of Physics, Institute for Research in Fundamental Sciences, PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Hoornam, S. [Nano Mabna Iranian Inc., PO Box 1676664116, Tehran (Iran, Islamic Republic of); School of Physics, Institute for Research in Fundamental Sciences, PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Science, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Vesaghi, M.A. [Department of Physics, Sharif University of Technology, PO Box 11365-9161, Tehran (Iran, Islamic Republic of); Ranjbar, B.; Azizi, A. [Department of Biophysics, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Mobasheri, H. [Laboratory of Membrane Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, PO Box 13145-1384, Tehran (Iran, Islamic Republic of); Biomaterials Research Institute (BRC), University of Tehran, Tehran (Iran, Islamic Republic of)

    2014-09-30

    Highlights: • We synthesized localized surface plasmon resonance sensor of gold nanoparticles by RF-sputtering and RF-PECVD. • LSPR sensor was characterized by TEM, XPS, AFM. • LSPR sensor was utilized to detect interaction between sorbitol and trehalose, with Pesudomonace Cepacia Lipase (PCL). • Unlike to trehalose, sorbitol interacts with the PCL. • Refractive index of PCL was obtained by Mie theory modeling. - Abstract: Co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target were used to prepare sensor chip of gold nanoparticles (Au NPs). Deposition conditions were optimized to reach a Localized Surface Plasmon Resonance (LSPR) sensor chip of Au NPs with particle size less than 10 nm. The RF power was set at 180 W and the initial gas pressure was set at 0.035 mbar. Transmission Electron Microscopy (TEM) images and Atomic Force Microscopy (AFM) data were used to investigate particles size and surface morphology of LSPR sensor chip. The Au and C content of the LSPR sensor chip of Au NPs was obtained from X-ray photoelectron spectroscopy (XPS). The hydrogenated amorphous carbon (a-C:H) thin film was used as intermediate material to immobilize Au NPs on the SiO{sub 2} substrate. The interaction between two types of osmolytes, i.e. sorbitol and trehalose, with Pseudomonas cepacia lipase (PCL) were detected by the prepared LSPR biosensor chip. The detection mechanism is based on LSPR spectroscopy in which the wavelength of absorption peak is sensitive to the refractive index of the environment of the Au NPs. This mechanism eliminates the use of a probe or immobilization of PCL on the Au NPs of LSPR sensor chip. The interaction between PCL and osmolytes can change refractive index of the mixture or solution. We found that unlike to trehalose, sorbitol interacts with the PCL. This interaction increases refractive index of the PCL and sorbitol mixture. Refractive index of PCL in the presence of different concentration of sorbitol was

  7. Hypotaurine, N-methyltaurine, taurine, and glycine betaine as dominant osmolytes of vestimentiferan tubeworms from hydrothermal vents and cold seeps.

    Science.gov (United States)

    Yin, M; Palmer, H R; Fyfe-Johnson, A L; Bedford, J J; Smith, R A; Yancey, P H

    2000-01-01

    Organic osmolytes, solutes that regulate cell volume, occur at high levels in marine invertebrates. These are mostly free amino acids such as taurine, which are "compatible" with cell macromolecules, and methylamines such as trimethylamine oxide, which may have a nonosmotic role as a protein stabilizer, and which is higher in many deep-sea animals. To better understand nonosmotic roles of osmolytes, we used high-performance liquid chromatography and (1)H-nuclear magnetic resonance (NMR) to analyze vestimentiferans (vestimentum tissue) from unusual marine habitats. Species from deep hydrothermal vents were Riftia pachyptila of the East Pacific Rise (2,636 m) and Ridgeia piscesae of the Juan de Fuca Ridge (2,200 m). Species from cold hydrocarbon seeps were Lamellibrachia sp. and an unnamed escarpid species from subtidal sediment seeps (540 m) off Louisiana and Lamellibrachia barhami from bathyal tectonic seeps (1,800-2,000 m) off Oregon. Riftia were dominated by hypotaurine (152 mmol/kg wet wt), an antioxidant, and an unidentified solute with an NMR spectrum consistent with a methylamine. Ridgeia were dominated by betaine (N-trimethylglycine; 109 mmol/kg), hypotaurine (64 mmol/kg), and taurine (61 mmol/kg). The escarpids were dominated by taurine (138 mmol/kg) and hypotaurine (69 mmol/kg). Both Lamellibrachia populations were dominated by N-methyltaurine (209-252 mmol/kg), not previously reported as a major osmolyte, which may be involved in methane and sulfate metabolism. Trunk and plume tissue of the Oregon Lamellibrachia were nearly identical to vestimentum in osmolyte composition. The methylamines may also stabilize proteins against pressure; they were significantly higher in the three deeper-dwelling groups.

  8. Effect of Small Molecule Osmolytes on the Self-Assembly and Functionality of Globular Protein-Polymer Diblock Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Carla S.; Xu, Liza; Olsen, Bradley D. [MIT

    2013-12-05

    Blending the small molecule osmolytes glycerol and trehalose with the model globular protein–polymer block copolymer mCherry-b-poly(N-isopropyl acrylamide) (mCherry-b-PNIPAM) is demonstrated to improve protein functionality in self-assembled nanostructures. The incorporation of either additive into block copolymers results in functionality retention in the solid state of 80 and 100% for PNIPAM volume fractions of 40 and 55%, respectively. This represents a large improvement over the 50–60% functionality observed in the absence of any additive. Furthermore, glycerol decreases the thermal stability of block copolymer films by 15–20 °C, while trehalose results in an improvement in the thermal stability by 15–20 °C. These results suggest that hydrogen bond replacement is responsible for the retention of protein function but suppression or enhancement of thermal motion based on the glass transition of the osmolyte primarily determines thermal stability. While both osmolytes are observed to have a disordering effect on the nanostructure morphology with increasing concentration, this effect is less pronounced in materials with a larger polymer volume fraction. Glycerol preferentially localizes in the protein domains and swells the nanostructures, inducing disordering or a change in morphology depending on the PNIPAM coil fraction. In contrast, trehalose is observed to macrophase separate from the block copolymer, which results in nanodomains becoming more disordered without changing significantly in size.

  9. Drought Induced Changes in Growth, Osmolyte Accumulation and Antioxidant Metabolism of Three Maize Hybrids

    Science.gov (United States)

    Anjum, Shakeel A.; Ashraf, Umair; Tanveer, Mohsin; Khan, Imran; Hussain, Saddam; Shahzad, Babar; Zohaib, Ali; Abbas, Farhat; Saleem, Muhammad F.; Ali, Iftikhar; Wang, Long C.

    2017-01-01

    Consequences of drought stress in crop production systems are perhaps more deleterious than other abiotic stresses under changing climatic scenarios. Regulations of physio-biochemical responses of plants under drought stress can be used as markers for drought stress tolerance in selection and breeding. The present study was conducted to appraise the performance of three different maize hybrids (Dong Dan 80, Wan Dan 13, and Run Nong 35) under well-watered, low, moderate and SD conditions maintained at 100, 80, 60, and 40% of field capacity, respectively. Compared with well-watered conditions, drought stress caused oxidative stress by excessive production of reactive oxygen species (ROS) which led to reduced growth and yield formation in all maize hybrids; nevertheless, negative effects of drought stress were more prominent in Run Nong 35. Drought-induced osmolyte accumulation and strong enzymatic and non-enzymatic defense systems prevented the severe damage in Dong Dan 80. Overall performance of all maize hybrids under drought stress was recorded as: Dong Dan 80 > Wan Dan 13 > Run Nong 35 with 6.39, 7.35, and 16.55% yield reductions. Consequently, these biochemical traits and differential physiological responses might be helpful to develop drought tolerance genotypes that can withstand water-deficit conditions with minimum yield losses. PMID:28220130

  10. Anion-π catalysis.

    Science.gov (United States)

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

    2014-02-05

    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

  11. The use of trimethylamine N-oxide as a primary precipitating agent and related methylamine osmolytes as cryoprotective agents for macromolecular crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Haley; Venkat, Murugappan; Hti Lar Seng, Nang San; Cahn, Jackson [Whitman College, Walla Walla, Washington (United States); Juers, Douglas H., E-mail: juersdh@whitman.edu [Whitman College, Walla Walla, Washington (United States); Whitman College, Walla Walla, Washington (United States)

    2012-01-01

    The stabilizing osmolyte trimethylamine N-oxide (TMAO) is shown to be an efficient primary precipitant for protein crystal growth. In addition to TMAO, two other methylamine osmolytes, sarcosine and betaine, are shown to be effective cryoprotective agents for protein crystal cooling. Both crystallization and cryoprotection are often bottlenecks for high-resolution X-ray structure determination of macromolecules. Methylamine osmolytes are known stabilizers of protein structure. One such osmolyte, trimethylamine N-oxide (TMAO), has seen occasional use as an additive to improve macromolecular crystal quality and has recently been shown to be an effective cryoprotective agent for low-temperature data collection. Here, TMAO and the related osmolytes sarcosine and betaine are investigated as primary precipitating agents for protein crystal growth. Crystallization experiments were undertaken with 14 proteins. Using TMAO, seven proteins crystallized in a total of 13 crystal forms, including a new tetragonal crystal form of trypsin. The crystals diffracted well, and eight of the 13 crystal forms could be effectively cryocooled as grown with TMAO as an in situ cryoprotective agent. Sarcosine and betaine produced crystals of four and two of the 14 proteins, respectively. In addition to TMAO, sarcosine and betaine were effective post-crystallization cryoprotective agents for two different crystal forms of thermolysin. Precipitation reactions of TMAO with several transition-metal ions (Fe{sup 3+}, Co{sup 2+}, Cu{sup 2+} and Zn{sup 2+}) did not occur with sarcosine or betaine and were inhibited for TMAO at lower pH. Structures of proteins from TMAO-grown crystals and from crystals soaked in TMAO, sarcosine or betaine were determined, showing osmolyte binding in five of the 12 crystals tested. When an osmolyte was shown to bind, it did so near the protein surface, interacting with water molecules, side chains and backbone atoms, often at crystal contacts.

  12. Effect of chemical exchange on radiation damping in aqueous solutions of the osmolyte glycine.

    Science.gov (United States)

    Rodríguez, Juan Carlos; Jennings, Patricia A; Melacini, Giuseppe

    2002-06-05

    Radiation damping is of central relevance in NMR spectroscopy especially with the advent of ultrahigh-field magnets and of supersensitive probes. Furthermore, the recent realization that the combined effect of the distant dipole field and of radiation damping causes the resurrection of undesired crushed water magnetization emphasizes the need for a thorough understanding of all the factors affecting radiation damping. While the effects of pulsed-field gradients and of active feedback have been extensively investigated, the consequences on radiation damping of chemical exchange between water and co-solutes is not as well understood. Here it is demonstrated that the rate of water radiation damping is significantly affected by free glycine (Gly), a representative of an important class of biocompatible osmolytes often used at molar concentrations as protein stabilizers. The pH and temperature dependencies of this effect were investigated and rationalized in terms of radiation damping attenuation caused by incoherent dephasing occurring in the intermediate exchange regime. For instance, at pH 6.0 and at a temperature of 313 K the Gly NH3+/water exchange has the same dramatic effect on radiation damping as a series of repeated weak PFGs, increasing the water inversion-recovery zero-crossing delay from approximately 30 ms to approximately 2.3 s. In addition, under these conditions, the Gly NH3+/water exchange suppresses the resurrection of unwanted crushed water magnetization. When used in combination with PFGs and water flip-back schemes, glycine is therefore expected to tame chaotic dynamics and improve the reproducibility of the NMR experiments affected by it.

  13. Potentiometric anion selective sensors

    NARCIS (Netherlands)

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

    1999-01-01

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

  14. Determination of the folding of proteins as a function of denaturants, osmolytes or ligands using circular dichroism

    Science.gov (United States)

    Greenfield, Norma J.

    2009-01-01

    Circular dichroism (CD) is an excellent tool for examining the interactions and stability of proteins. This protocol covers methods to obtain and analyze circular dichroism spectra to measure changes in the folding of proteins as a function of denaturants, osmolytes or ligands. Applications include determination of the free energy of folding of a protein, the effects of mutations on protein stability and the estimation of binding constants for the interactions of proteins with other proteins, DNA or ligands, such as substrates or inhibitors. The experiments take 2-5 h. PMID:17406529

  15. Organic osmolytes in aerobic bacteria from Mono Lake, an alkaline, moderately hypersaline environment

    Energy Technology Data Exchange (ETDEWEB)

    Ciulla, R.A.; Roberts, M.F. [Boston College, Chestnut Hill, MA (United States); Diaz, M.R.; Taylor, B.F. [Univ. of Miami, FL (United States)

    1997-01-01

    The identity and concentrations of intracellular organic solutes were determined by nuclear magnetic resonance spectroscopy for two strains of aerobic, gram-negative bacteria isolated from Mono Lake, California, an alkaline, moderately hypersaline lake. Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) was the major endogenous solute in both organisms. Concentrations of ectoine varied with external NaCl levels in strain ML-D but not in strain ML-G, where the level was high but invariant from 1.5 to 3.0 M NaCl. Hydroxyectoine also occurred in strain ML-D, especially at elevated NaCl concentrations (2.5 and 3.0 M), but at levels lower than those of ectoine. Exogenous organic solutes that might occur in Mono Lake were examined for their effects on the de novo synthesis of ectoine. Dimethylsulfoniopropionate (DMSP) (0.1 or 1 mM) did not significantly lower ectoine levels in either isolate, and only strain ML-G showed any capacity for DMSP accumulation. With nitrogen limitation, however, DMSP (0.1 mM) substituted for ectoine in strain ML-G showed any capacity for DMSP accumulation. With nitrogen limitation, however, DMSP (0.1 mM) substituted for ectoine in strain ML-G and became the main organic solute. Glycine betaine (GB) was more effective than DMSP in affecting ectoine levels, principally in strain ML-D. Strain ML-D accumulated GB to 50 or 67% of its organic solute pool at 2.5 M NaCl, at an external level of 0.1 or 1 mM GB, respectively. Strain ML-D also accumulated arsenobetaine. The methylated zwitterionic compounds, probably metabolic products of phytoplankton (DMSP and GB) or brine shrimps (arsenobetaine) in Mono Lake, may function as osmolytes for indigenous bacteria when present at high concentrations or under conditions of nitrogen limitation or salt stress. 33 refs., 5 figs., 2 tabs.

  16. Effects of Salt and Water Stress on Plant Growth and on Accumulation of Osmolytes and Antioxidant Compounds in Cherry Tomato

    Directory of Open Access Journals (Sweden)

    Mohamad AL HASSAN

    2015-04-01

    Full Text Available The effects of salt and water stress on growth and several stress markers were investigated in cherry tomato plants. Some growth parameters (stem length and number of leaves and chlorophyll contents were determined every third day during plant growth, and leaf material was collected after 25 and 33 days of treatment. Both stresses inhibited plant growth; chlorophyll levels, however, decreased only in response to high NaCl concentrations. Proline contents largely increased in leaves of stressed plants, reaching levels high enough to play a major role in cellular osmotic adjustment. Despite reports indicating that tomato does not synthesize glycine betaine, the stress-induced accumulation of this osmolyte was detected in cherry tomato, albeit at lower concentration than that of proline. Therefore, it appears that the plants are able to synthesise glycine betaine as a secondary osmolyte under strong stress conditions. Total sugars levels, on the contrary, decreased in stress-treated plants. Both stress treatments caused secondary oxidative stress in the plants, as indicated by a significant increase in malondialdehyde (MDA contents. Water stress led to an increase in total phenolics and flavonoid contents and a reduction of carotenoid levels in the leaves; flavonoids also increased under high salinity conditions.

  17. Conformational dynamics of a hydrophobic prion fragment (113-127) in different pH and osmolyte solutions.

    Science.gov (United States)

    Inayathullah, Mohammed; Rajadas, Jayakumar

    2016-06-01

    Prion diseases are characterized by a conformational change in prion protein from its native state into beta-sheet rich aggregates that are neurotoxic. The central domain that contain a highly conserved hydrophobic region of the protein play an important role in the toxicity. The conformation of the proteins is largely influenced by various solvent environments. Here we report results of study of hydrophobic prion fragment peptide PrP(113-127) under different pH and osmolytes solution conditions. The secondary structure and the folding of PrP(113-127) was determined using circular dichroism and fluorescence spectroscopic methods. The results indicate that PrP(113-127) adopts a random coil conformation in aqueous buffer at neutral pH and that converted into beta sheet on aging. Even though the initial random coil conformation was similar in different pH conditions, the acidic as well as basic pH conditions delays the conformational transition to beta sheet. FRET results indicate that the distance between N and C-terminal regions increased on aging due to unfolding by self-assembly of the peptide into an organized beta sheet structure. Presence of osmolytes, prevented or decelerated the aggregation process of PrP(113-127) peptide. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Ravshan Z. Sabirov

    2011-12-01

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

  19. Resonant spectra of quadrupolar anions

    CERN Document Server

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

    2016-01-01

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

  20. Folding recombinant spider-silk in H2 O: Effect of osmolytes on the solution conformation of a 15-repeat spider-silk mimetic.

    Science.gov (United States)

    McLachlan, Glendon D; Gandjian, Babak; Alhumaidan, Hind

    2016-10-01

    The folding of a recombinant spider silk protein-polymer in the presence of the tri-methylamine osmolytes TMANO and Betaine in 80% H2 O is reported. Circular dichroism measurements (CD) reveal an increase in α-helical secondary structure with increasing osmolyte concentrations, as determined by an increase in ellipticity at 222 nm. Consistent with this observation, the signal for random coil sampling, observed at 205 nm, is greatly reduced with increasing trimethylamine. Fluorescence spectra of a single tyrosine positioned within the conserved 33-amino acid repeat primary sequence (of the spider-silk mimetic) complements the conformational changes observed by CD. Importantly, there is a correlation between the number of Alkyl-groups (CH3 -) on the amine of the osmolyte and enhanced helicity of the 15-repeat silk-mimetic for the osmolytes tested, ie TMANO, Betaine, Sarcosine and Glycine. These preliminary results are applicable to storing and processing recombinant silk sequences in H2 O, an important mile-stone for widespread use of recombinant silk polymers. © 2016 The Protein Society.

  1. Mammalian osmolytes and S-nitrosoglutathione promote Delta F508 cystic fibrosis transmembrane conductance regulator (CFTR) protein maturation and function.

    Science.gov (United States)

    Howard, Marybeth; Fischer, Horst; Roux, Jeremie; Santos, Bento C; Gullans, Steven R; Yancey, Paul H; Welch, William J

    2003-09-12

    In cystic fibrosis, the absence of functional CFTR results in thick mucous secretions in the lung and intestines, as well as pancreatic deficiency. Although expressed at high levels in the kidney, mutations in CFTR result in little or no apparent kidney dysfunction. In an effort to understand this phenomenon, we analyzed Delta F508 CFTR maturation and function in kidney cells under conditions that are common to the kidney, namely osmotic stress. Kidney cells were grown in culture and adapted to 250 mM NaCl and 250 mM urea. High performance liquid chromatography analysis of lysates from kidney cells adapted to these conditions identified an increase in the cellular osmolytes glycerophosphorylcholine, myo-inositol, sorbitol, and taurine. In contrast to isoosmotic conditions, hyperosmotic stress led to the proper folding and processing of Delta F508 CFTR. Furthermore, three of the cellular osmolytes, when added individually to cells, proved effective in promoting the proper folding and processing of the Delta F508 CFTR protein in both epithelial and fibroblast cells. Whole-cell patch clamping of osmolyte-treated cells showed that Delta F508 CFTR had trafficked to the plasma membrane and was activated by forskolin. Encouraged by these findings, we looked at other features common to the kidney that may impact Delta F508 maturation and function. Interestingly, a small molecule, S-nitrosoglutathione, which is a substrate for gamma glutamyltranspeptidase, an abundant enzyme in the kidney, likewise promoted Delta F508 CFTR maturation and function. S-Nitrosoglutathione-corrected Delta F508 CFTR exhibited a shorter half-life as compared with wild type CFTR. These results demonstrate the feasibility of a small molecule approach as a therapeutic treatment in promoting Delta F508 CFTR maturation and function and suggest that an additional treatment may be required to stabilize Delta F508 CFTR protein once present at the plasma membrane. Finally, our observations may help to

  2. Anionic surface binders

    Directory of Open Access Journals (Sweden)

    Aljaž-Rožič Mateja

    2004-01-01

    Full Text Available The MELAMIN Chemical Factory in Kočevje manufactures synthetic resins and binders for the paper industry. Binders based on AKD (alkyl ketene dimer are produced which are used for binding paper and cardboard in the range of neutral and partially basic pH. Cationic and, lately, anionic binders are mostly used for the bulk binding of paper and board. The possibility of using AKD binders on paper or board surfaces is presented. In this case partially cationic AKD binders may be applied. When optical whiteners are used, the application of AKD binders is recommended. In the case of paper it is possible to substitute acrylate binders by AKD binders. The best results are obtained when the paper is first partly treated in bulk and subsequently surface treated.

  3. Resonant spectra of quadrupolar anions

    Science.gov (United States)

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

    2016-09-01

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

  4. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

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

  5. Pentaarylfullerenes as noncoordinating cyclopentadienyl anions

    NARCIS (Netherlands)

    Bouwkamp, Marco W.; Meetsma, Auke

    2009-01-01

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

  6. Testing the dependence of stabilizing effect of osmolytes on the fractional increase in the accessible surface area on thermal and chemical denaturations of proteins.

    Science.gov (United States)

    Rahman, Safikur; Ali, Syed Ausaf; Islam, Asimul; Hassan, Md Imtaiyaz; Ahmad, Faizan

    2016-02-01

    Here we have generated two different denatured states using heat- and guanidinium chloride (GdmCl)-induced denaturations of three disulfide bond free proteins (barstar, cytochrome-c and myoglobin). We have observed that these two denatured states of barstar and myoglobin are structurally and energetically different, for, heat-induced denatured state contains many un-melted residual structure that has a significant amount of secondary and tertiary interactions. We show that structural properties of the denatured state determine the magnitude of the protein stabilization in terms of Gibbs free energy change (ΔGD°) induced by an osmolyte, i.e., the greater the exposed surface area, the greater is the stabilization. Furthermore, we predicted the m-values (ability of osmolyte to fold or unfold proteins) using Tanford's transfer-free energy model for the transfer of proteins to osmolyte solutions. We observed that, for each protein, m-value is comparable with our experimental data in cases of TMAO (trimethylamine-N-oxide) and sarcosine. However, a significant discrepancy between predicted and experimental m-values were observed in the case of glycine-betaine.

  7. Testing the ability of non-methylamine osmolytes present in kidney cells to counteract the deleterious effects of urea on structure, stability and function of proteins.

    Directory of Open Access Journals (Sweden)

    Sheeza Khan

    Full Text Available Human kidney cells are under constant urea stress due to its urine concentrating mechanism. It is believed that the deleterious effect of urea is counteracted by methylamine osmolytes (glycine betaine and glycerophosphocholine present in kidney cells. A question arises: Do the stabilizing osmolytes, non-methylamines (myo-inositol, sorbitol and taurine present in the kidney cells also counteract the deleterious effects of urea? To answer this question, we have measured structure, thermodynamic stability (ΔG D (o and functional activity parameters (K m and k cat of different model proteins in the presence of various concentrations of urea and each non-methylamine osmolyte alone and in combination. We observed that (i for each protein myo-inositol provides perfect counteraction at 1∶2 ([myo-inositol]:[urea] ratio, (ii any concentration of sorbitol fails to refold urea denatured proteins if it is six times less than that of urea, and (iii taurine regulates perfect counteraction in a protein specific manner; 1.5∶2.0, 1.2∶2.0 and 1.0∶2.0 ([taurine]:[urea] ratios for RNase-A, lysozyme and α-lactalbumin, respectively.

  8. Testing the Ability of Non-Methylamine Osmolytes Present in Kidney Cells to Counteract the Deleterious Effects of Urea on Structure, Stability and Function of Proteins

    Science.gov (United States)

    Khan, Sheeza; Bano, Zehra; Singh, Laishram R.; Hassan, Md. Imtaiyaz; Islam, Asimul; Ahmad, Faizan

    2013-01-01

    Human kidney cells are under constant urea stress due to its urine concentrating mechanism. It is believed that the deleterious effect of urea is counteracted by methylamine osmolytes (glycine betaine and glycerophosphocholine) present in kidney cells. A question arises: Do the stabilizing osmolytes, non-methylamines (myo-inositol, sorbitol and taurine) present in the kidney cells also counteract the deleterious effects of urea? To answer this question, we have measured structure, thermodynamic stability (ΔGDo) and functional activity parameters (Km and kcat) of different model proteins in the presence of various concentrations of urea and each non-methylamine osmolyte alone and in combination. We observed that (i) for each protein myo-inositol provides perfect counteraction at 1∶2 ([myo-inositol]:[urea]) ratio, (ii) any concentration of sorbitol fails to refold urea denatured proteins if it is six times less than that of urea, and (iii) taurine regulates perfect counteraction in a protein specific manner; 1.5∶2.0, 1.2∶2.0 and 1.0∶2.0 ([taurine]:[urea]) ratios for RNase-A, lysozyme and α-lactalbumin, respectively. PMID:24039776

  9. Bound anionic states of adenine

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-20

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

  10. Anion exchange polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Exogenous glutathione improves high root-zone temperature tolerance by modulating photosynthesis, antioxidant and osmolytes systems in cucumber seedlings

    Science.gov (United States)

    Ding, Xiaotao; Jiang, Yuping; He, Lizhong; Zhou, Qiang; Yu, Jizhu; Hui, Dafeng; Huang, Danfeng

    2016-01-01

    To investigate the physiological responses of plants to high root-zone temperature (HT, 35 °C) stress mitigated by exogenous glutathione (GSH), cucumber (Cucumis sativus L.) seedlings were exposed to HT with or without GSH treatment for 4 days and following with 4 days of recovery. Plant physiological variables, growth, and gene expression related to antioxidant enzymes and Calvin cycle were quantified. The results showed that HT significantly decreased GSH content, the ratio of reduced to oxidized glutathione (GSH/GSSG), chlorophyll content, photosynthesis and related gene expression, shoot height, stem diameter, as well as dry weight. The exogenous GSH treatment clearly lessened the HT stress by increasing the above variables. Meanwhile, HT significantly increased soluble protein content, proline and malondialdehyde (MDA) content as well as O2•− production rate, the gene expression and activities of antioxidant enzymes. The GSH treatment remarkably improved soluble protein content, proline content, antioxidant enzymes activities, and antioxidant enzymes related gene expression, and reduced the MDA content and O2•− production rate compared to no GSH treatment in the HT condition. Our results suggest that exogenous GSH enhances cucumber seedling tolerance of HT stress by modulating the photosynthesis, antioxidant and osmolytes systems to improve physiological adaptation. PMID:27752105

  12. Amide-based Fluorescent Macrocyclic Anion Receptors

    Institute of Scientific and Technical Information of China (English)

    ZENG, Zhen-Ya(曾振亚); XU, Kuo-Xi(徐括喜); HE, Yong-Bing(何永炳); LIU, Shun-Ying(刘顺英); WU, Jin-Long(吴进龙); WEI, Lan-Hua(隗兰华); MENG, Ling-Zhi(孟令芝)

    2004-01-01

    Two fluorescent anion receptors (1 and 2) based on amide macrocycle were synthesized and corresponding fluorescence quenching induced by anion complexation was observed in different degree. Receptors form 1: 1 complexes with anions by hydrogen bonding interactions. Receptor 1 bound anions in the order of F->Cl->H2PO4->CH3COO->>Br-, I- and receptor 2 showed high selectivity to F- over other anions.

  13. Neutral and anionic superhalogen hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Swierszcz, Iwona [Department of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Anusiewicz, Iwona, E-mail: iwonaa@chem.univ.gda.pl [Department of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)

    2011-05-26

    Graphical abstract: The energy profile for the Na(OH){sub 2}{sup -} anionic hydroxide formation according to the NaOH+OH{sup -}{yields}Na(OH){sub 2}{sup -} reaction. Display Omitted Highlights: {yields} The superhalogen hydroxides and their anions were studied at the CCSD(T)/6-311++G(3df,3pd) level. {yields} All anionic superhalogen hydroxides were found to be thermodynamically stable. {yields} The VDE values calculated for the M(OH){sub k+1}{sup -} anions exceed 4 eV in all cases. {yields} The largest VDEs were found for the Al(OH){sub 4}{sup -} (6.07 eV) and Ga(OH){sub 4}{sup -} (6.21 eV). - Abstract: The properties of superhalogen M(OH){sub k+1}{sup -} anions and their M(OH){sub k+1} neutral parents (where M = Li, Na, K, Be, Mg, Ca, B, Al, Ga) were investigated at the ab initio CCSD(T)/6-311++G(3df,3pd)//MP2/6-311++G(d,p) level of theory. All the M(OH){sub k+1}{sup -} anions and some of their M(OH){sub k+1} neutral parents (k is the maximal formal valence of M) were found to be thermodynamically stable against the fragmentations (OH, OH{sup -}, O{sub 2} or H{sub 2}O loss). The vertical electron detachment energies (VDE) of the M(OH){sub k+1}{sup -} anions were calculated with the OVGF method and using the 6-311++G(3df,3pd) basis sets. The VDE values calculated for the anions studied exceed 4 eV in all cases, whereas the largest values of the electron binding energies were found for the Al(OH){sub 4}{sup -} (6.07 eV) and Ga(OH){sub 4}{sup -} anions (6.21 eV). Finally, formation of most of the species considered was predicted to be spontaneous due to the lack of kinetic barriers for these processes and their thermodynamic favorability.

  14. Anions in Nucleic Acid Crystallography.

    Science.gov (United States)

    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. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-08

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

  16. Activation and inactivation of the volume-sensitive taurine leak pathway in NIH3T3 fibroblasts and Ehrlich Lettre ascites cells

    DEFF Research Database (Denmark)

    Lambert, Ian Henry

    2007-01-01

    Hypotonic exposure provokes the mobilization of arachidonic acid, production of ROS, and a transient increase in taurine release in Ehrlich Lettre cells. The taurine release is potentiated by H(2)O(2) and the tyrosine phosphatase inhibitor vanadate and reduced by the phospholipase A(2) (PLA(2......)) inhibitors bromoenol lactone (BEL) and manoalide, the 5-lipoxygenase (5-LO) inhibitor ETH-615139, the NADPH oxidase inhibitor diphenyl iodonium (DPI), and antioxidants. Thus, swelling-induced taurine efflux in Ehrlich Lettre cells involves Ca(2+)-independent (iPLA(2))/secretory PLA(2) (sPLA(2)) plus 5-LO...... activity and modulation by ROS. Vanadate and H(2)O(2) stimulate arachidonic acid mobilization and vanadate potentiates ROS production in Ehrlich Lettre cells and NIH3T3 fibroblasts under hypotonic conditions. However, vanadate-induced potentiation of the volume-sensitive taurine efflux is, in both cell...

  17. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Michael Rajamathi; Grace S Thomas; P Vishnu Kamath

    2001-10-01

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

  18. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-15

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

  19. Anion binding in biological systems

    Science.gov (United States)

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

    2009-11-01

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

  20. Tripodal Receptors for Cation and Anion Sensors

    NARCIS (Netherlands)

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

    2006-01-01

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

  1. Efficient Amide Based Halogenide Anion Receptors

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  2. Binding Hydrated Anions with Hydrophobic Pockets.

    Science.gov (United States)

    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.

  3. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad

    2016-08-18

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  4. Laser Cooling of Molecular Anions

    CERN Document Server

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

    2015-01-01

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

  5. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

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

    2006-01-31

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

  6. Laser cooling of molecular anions.

    Science.gov (United States)

    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.

  7. The interaction of certain inorganic anions with clays and soils

    NARCIS (Netherlands)

    Haan, de F.A.M.

    1965-01-01

    Interaction between anions and soil colloids was governed by 2 antagonistic processes, anion exclusion and positive anion adsorption. The predominantly negative charge on the colloids caused anion repulsion; positively charged sites and chemisorption resulted in positive

  8. Ionol (BHT) produces superoxide anion.

    Science.gov (United States)

    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.

  9. Hosting anions. The energetic perspective.

    Science.gov (United States)

    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).

  10. Comparative analysis of naturally occurring L-amino acid osmolytes and their D-isomers on protection of Escherichia coli against environmental stresses

    Indian Academy of Sciences (India)

    Hanief Md Shahjee; Kakoli Banerjee; Faizan Ahmad

    2002-09-01

    Adaptation to high salinity and low or high temperature is essential for bacteria to survive. Accumulation of exogenous osmolytes is one of the ways that helps bacteria to survive under such extracellular stress. We have analysed the capability of various L-amino acids and their D-isomers to act as osmolytes and thus enable Escherichia coli cells to survive under various stress conditions. E. coli cells were grown in the presence or absence of L- and D-proline, alanine, serine and lysine under salt, heat and cold stresses. Of the various amino acids tested, L-proline, closely followed by L-serine turned out to be highly protective against environmental stresses. L-proline provided excellent protection (95%) against salt stress, followed by cold (60%) and heat (40%) stresses. D-amino acids on the other hand, proved to be highly inhibitory under stress conditions. Thus L-amino acids were found to be growth protectants under stress while their D-isomers were inhibitory during stress as well as normal conditions.

  11. Synergistic effect of antioxidant system and osmolyte in hydrogen sulfide and salicylic acid crosstalk-induced heat tolerance in maize (Zea mays L.) seedlings.

    Science.gov (United States)

    Li, Zhong-Guang

    2015-01-01

    Salicylic acid (SA), is a plant hormone with multifunction that is involved in plant growth, development and the acquisition of stress tolerance. Hydrogen sulfide (H2S) is emerging similar functions, but crosstalk between SA and H2S in the acquisition of heat tolerance is not clear. Our recent study firstly reported that SA treatment enhanced the activity of L-cysteine desulfhydrase (L-DES), a key enzyme in H2S biosynthesis, followed by induced endogenous H2S accumulation, which in turn improved the heat tolerance of maize seedlings. (1) In addition, NaHS, a H2S donor, enhanced SA-induced heat tolerance, while its biosynthesis inhibitor DL-propargylglycine (PAG) and scavenger hydroxylamine (HT) weakened SA-induced heat tolerance. Also, NaHS had no significant effect on SA accumulation and its biosynthesis enzymes phenylalanine ammonia lyase (PAL) and benzoic-acid-2-hydroxylase (BA2H) activities, as well as significant difference was not observed in NaHS-induced heat tolerance of maize seedlings by SA biosynthesis inhibitors paclobutrazol (PAC) and 2-aminoindan-2-phosph- onic acid (AIP) treatment. (1) Further study displayed that SA induced osmolytes (proline, betaine and trehalose) accumulation and enhancement in activity of antioxidant system in maize seedlings. These results showed that antioxidant system and osmolyte play a synergistic role in SA and H2S crosstalk-induced heat tolerance of maize seedlings.

  12. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

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

  13. Vibrational Autodetachment in Nitroalkane Anions

    Science.gov (United States)

    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.

  14. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  15. Tunable electronic interactions between anions and perylenediimide.

    Science.gov (United States)

    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.

  16. Adsorption affinity of anions on metal oxyhydroxides

    Science.gov (United States)

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

    2013-03-01

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

  17. Role of androgen receptor polyQ chain elongation in Kennedy's disease and use of natural osmolytes as potential therapeutic targets.

    Science.gov (United States)

    Kumar, Raj

    2012-11-01

    Instability of CAG triplet repeat encoding polyglutamine (polyQ) stretches in the gene for target protein has been implicated as a putative mechanism in several inherited neurodegenerative diseases. Expansion of polyQ chain length in the androgen receptor (AR) causes spinal and bulbar muscular atrophy (SBMA) or Kennedy's disease. Although the mechanisms underlying gain-of-neurotoxic function are not completely understood, suggested pathological mechanisms of SBMA involve the formation of AR nuclear and cytoplasmic aggregates, a characteristic feature of patients with SBMA. The fact that certain AR coactivators are sequestered into the nuclear inclusions in SBMA possibly through protein-protein interactions supports the notion that AR transcriptional dysregulation may be a potential pathological mechanism leading to SBMA. AR conformational states associated with aberrant polyQ tract also modulate the interaction of AR with several coactivators. In many cases, such diseases can be treated through protein replacement therapy; however, because recombinant proteins do not cross the blood-brain barrier, the effectiveness of such therapies is limited in case of neurodegenerative diseases that warrant alternative therapeutic approaches. Among different approaches, inhibiting protein aggregation with small molecules that can stimulate protein folding and reverse aggregation are the most promising ones. Thus, naturally occurring osmolytes or "chemical chaperones" that can easily cross the blood-brain barrier and stabilize the functional form of a mutated protein by shifting the folding equilibrium away from degradation and/or aggregation is a useful therapeutic approach. In this review, we discuss the role of polyQ chain length extension in the pathophysiology of SBMA and the use of osmolytes as potential therapeutic tool.

  18. Ursodeoxycholic acid and superoxide anion

    Institute of Scientific and Technical Information of China (English)

    Predrag Ljubuncic; Omar Abu-Salach; Arieh Bomzon

    2005-01-01

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

  19. Vibrational Spectroscopy of Microhydrated Conjugate Base Anions

    NARCIS (Netherlands)

    Asmis, K. R.; Neumark, D. M.

    2012-01-01

    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 aeros

  20. Creating molecular macrocycles for anion recognition

    Directory of Open Access Journals (Sweden)

    Amar H. Flood

    2016-03-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  2. Supramolecular electron transfer by anion binding.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  4. Molecular anions sputtered from fluorides

    CERN Document Server

    Gnaser, H

    2002-01-01

    The emission of negatively charged ions from different fluoride samples (LiF, CaF sub 2 , LaF sub 3 and HfF sub 4) induced by sputtering with a 14.5-keV Cs sup + ion beam was studied. Sputtered ions were detected in a high-sensitivity double-focusing mass spectrometer. In particular, the possible existence of small doubly charged negative molecular ions was investigated. But whereas singly charged species of the general type MF sub n sup - (where M represents a metal atom) were detected with high abundances, stable dianions were observed in an unambiguous way only for one molecule: HfF sub 6 sup 2 sup -. The flight time through the mass spectrometer of approx 35 mu s establishes a lower limit with respect to the intrinsic lifetime of this doubly charged ion. For singly charged anions abundance distributions and, in selected cases, emission-energy spectra were recorded. For two ion species (Ca sup - and HfF sub 5 sup -) isotopic fractionation effects caused by the (velocity dependent) ionization process were d...

  5. Anion photoelectron imaging spectroscopy of glyoxal

    Science.gov (United States)

    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.

  6. Renal elimination of organic anions in cholestasis

    Institute of Scientific and Technical Information of China (English)

    Adriana Mónica Tortes

    2008-01-01

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

  7. Gas-Phase Reactivity of Microsolvated Anions

    DEFF Research Database (Denmark)

    Thomsen, Ditte Linde

    intrinsic factors and solvent effects is the enhanced reactivity of α-nucleophiles – nucleophiles with a lone-pair adjacent to the attacking site – referred to as the α-effect. This thesis concerns the reactivity of microsolvated anions and in particular how the presence of a single solvent molecule affects...... the gas-phase α-effect. The experimental studies are performed by means of the flowing after glow selected ion flow tube technique, and these are supplemented by electronic structure calculations. The α-nucleophile employed is the microsolvated hydrogen peroxide anion whose reactivity is compared...... to that of a series of microsolvated oxygen centered anions. The association of the nucleophiles with a single water or methanol molecule allows the α-effect to be observed in the SN2 reaction with methyl chloride; this effect was not apparent in the reactions of the unsolvated anions. The results suggest...

  8. A new class of organocatalysts: sulfenate anions.

    Science.gov (United States)

    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.

  9. Fluorescence-lifetime-based sensors for anions

    Science.gov (United States)

    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.

  10. Neutral pyrimidine C-H donor as anion receptor

    Institute of Scientific and Technical Information of China (English)

    袁迎雪; 吴娜娜; 韩逸飞; 宋相志; 王洪波

    2016-01-01

    Anion receptors including pyrimidine subunit were designed and synthesized and their binding abilities with various anions were investigated by fluorescence and 1H NMR titration experiments. DFT calculations provided some information for anion recognition. It is confirmed that both of two new pyrimidine anion receptors have the selectivity for Cl−.

  11. The putative Na⁺/Cl⁻-dependent neurotransmitter/osmolyte transporter inebriated in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.

    Science.gov (United States)

    Luan, Zhuo; Quigley, Caitlin; Li, Hong-Sheng

    2015-01-23

    Most organisms are able to maintain systemic water homeostasis over a wide range of external or dietary osmolarities. The excretory system, composed of the kidneys in mammals and the Malpighian tubules and hindgut in insects, can increase water conservation and absorption to maintain systemic water homeostasis, which enables organisms to tolerate external hypertonicity or desiccation. However, the mechanisms underlying the maintenance of systemic water homeostasis by the excretory system have not been fully characterized. In the present study, we found that the putative Na(+)/Cl(-)-dependent neurotransmitter/osmolyte transporter inebriated (ine) is expressed in the basolateral membrane of anterior hindgut epithelial cells. This was confirmed by comparison with a known basolateral localized protein, the α subunit of Na(+)-K(+) ATPase (ATPα). Under external hypertonicity, loss of ine in the hindgut epithelium results in severe dehydration without damage to the hindgut epithelial cells, implicating a physiological failure of water conservation/absorption. We also found that hindgut expression of ine is required for water conservation under desiccating conditions. Importantly, specific expression of ine in the hindgut epithelium can completely restore disrupted systemic water homeostasis in ine mutants under both conditions. Therefore, ine in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.

  12. The organic osmolyte betaine induces keratin 2 expression in rat epidermal keratinocytes - A genome-wide study in UVB irradiated organotypic 3D cultures.

    Science.gov (United States)

    Rauhala, Leena; Hämäläinen, Lasse; Dunlop, Thomas W; Pehkonen, Petri; Bart, Geneviève; Kokkonen, Maarit; Tammi, Markku; Tammi, Raija; Pasonen-Seppänen, Sanna

    2015-12-25

    The moisturizing and potentially protective properties of the organic osmolyte betaine (trimethylglycine) have made it an attractive component for skin care products. Its wide use despite the lack of comprehensive studies addressing its specific effects in skin led us to characterize the molecular targets of betaine in keratinocytes and to explore, whether it modifies the effects of acute UVB exposure. Genome-wide expression analysis was performed on organotypic cultures of rat epidermal keratinocytes, treated either with betaine (10mM), UVB (30 mJ/cm(2)) or their combination. Results were verified with qRT-PCR, western blotting and immunohistochemistry. Additionally, cell proliferation and differentiation were analyzed. Among the 89 genes influenced by betaine, the differentiation marker keratin 2 showed the highest upregulation, which was also confirmed at protein level. Expression of Egr1, a transcription factor, and Purkinje cell protein 4, a regulator of Ca(2+)/calmodulin metabolism, also increased, while downregulated genes included several ion-channel components, such as Fxyd2. Bioinformatics analyses suggest that genes modulated by betaine are involved in DNA replication, might counteract UV-induced processes, and include many targets of transcription factors associated with cell proliferation and differentiation. Our results indicate that betaine controls unique gene expression pathways in keratinocytes, including some involved in differentiation.

  13. Studies of anions sorption on natural zeolites.

    Science.gov (United States)

    Barczyk, K; Mozgawa, W; Król, M

    2014-12-10

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

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

    Science.gov (United States)

    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.

  15. Vibrational spectroscopy of microhydrated conjugate base anions.

    Science.gov (United States)

    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

  16. An anionic surfactant for EOR applications

    Science.gov (United States)

    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.

  17. Identification and characterization of anion binding sites in RNA

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-24

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

  18. Templating irreversible covalent macrocyclization by using anions.

    Science.gov (United States)

    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.

  19. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  20. Krebs cycle anions in metabolic acidosis.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  2. 24-epibrassinolide modulates growth, nodulation, antioxidant system, and osmolyte in tolerant and sensitive varieties of Vigna radiata under different levels of nickel: a shotgun approach.

    Science.gov (United States)

    Yusuf, M; Fariduddin, Q; Ahmad, A

    2012-08-01

    The objective of this study was to explore the response of 24-epibrassinolide to improve the biological yield of Ni-tolerant and Ni-sensitive varieties of Vigna radiata and also to test the propositions that 24-epibrassinolide induced up-regulation of antioxidant system protects the efficiency of V. radiata, grown under Ni-stress. Surface sterilized seeds of var. T-44 (Ni-tolerant) and PDM-139 (Ni-sensitive) were soaked in DDW (control), 10(-10), 10(-8), or 10(-6) M of 24-epibrassinolide for 8 h (shotgun approach). These treated seeds were then inoculated with specific Rhizobium grown in sandy loam soil supplemented with different levels of Ni 0, 50, 100, or 150 mg Ni kg(-1) of soil and were allowed to grow for 45-days. At this stage of growth, plants were sampled to assess the various growths and nodule related traits as well as selected biochemical characteristics. The remaining plants were allowed to grow to maturity to study the yield characteristics. The results indicated that plant-fresh and dry mass, number of nodules, their fresh and dry mass, leghemoglobin content, nitrogen and carbohydrate content in the nodules, leaf chlorophyll content, activities of nitrate reductase and carbonic anhydrase decreased proportionately with the increasing concentrations of soil nickel. However, the application of 24-epibrassinolide as shotgun approach (pre-sowing seed soaking) to the nickel-stressed or non-stressed plants improved growth, nodulation and enhanced the activity of various antioxidant enzymes (viz. catalase, peroxidase and superoxide dismutase) and also the content of proline. The up-regulation of antioxidant enzymes as well as proline (osmolyte) triggered by 24-epibrassinolide could have conferred tolerance to the Ni-stressed plants resulting in improved growth, nodulation and yield attributes. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  3. Molecular analysis of the role of osmolyte transporters opuCA and betL in Listeria monocytogenes after cold and freezing stress.

    Science.gov (United States)

    Miladi, Hanene; Elabed, Hamouda; Ben Slama, Rihab; Rhim, Amel; Bakhrouf, Amina

    2017-03-01

    Listeria monocytogenes is a food-borne pathogen of humans and other animals. The striking ability to survive several stresses usually used for food preservation makes L. monocytogenes one of the biggest concerns to the food industry. This ubiquity can be partly explained by the ability of the organism to grow and persist at very low temperatures, a consequence of its ability to accumulate cryoprotective compound called osmolytes. A quantitative RT-PCR assay was used to measure mRNA transcript accumulation for the stress response genes opuCA and betL (encoding carnitine and betaine transporters, respectively) and the housekeeping gene 16S rRNA. Assays were conducted on mid-exponential phase L. monocytogenes cells exposed to conditions reflecting cold and freezing stress, conditions usually used to preserve foods. We showed that expression of the two cold-adapted genes encoded the transporters of the cryoprotectants carnitine and betaine in ATCC 19115 and the food-isolated L. monocytogenes S1 is induced after cold and freezing stress exposure. Furthermore, transcriptional analysis of the genes encoding opuCA and betL revealed that each transporter is induced to different degrees upon cold shock of L. monocytogenes ATCC 19115 and S1. Our results confirm an increase in carnitine uptake at low temperatures more than in betaine after cold-shocked temperature compared to the non-stress control treatment. It was concluded the use of carnitine and betaine as cryoprotectants is essential for rapid induction of the tested stress response under conditions typically encountered during food preservation.

  4. Anionic/cationic complexes in hair care.

    Science.gov (United States)

    O'Lenick, Tony

    2011-01-01

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

  5. Stoichiometry of uranyl salophene anion complexes

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Ruel, Bianca H.M.; Engbersen, Johannes F.J.; Reinhoudt, David

    1998-01-01

    In PVC/NPOE ion-selective membranes of potentiometric sensors, the guest-host stoichiometry of the anion complex of H2PO4 - and F- selective uranyl salophene derivatives is 2:1. This stoichiometry is different from the stoichiometry observed in DMSO solution (1H NMR) or solid state (X-ray crystal

  6. Wigner photoemission time delay from endohedral anions

    Science.gov (United States)

    Kumar, Ashish; Varma, Hari R.; Deshmukh, Pranawa C.; Manson, Steven T.; Dolmatov, Valeriy K.; Kheifets, Anatoli

    2016-10-01

    Characteristic features of Wigner photoemission time delay from endohedral anions A@C60q along with their dependence on the anion charge q are unraveled. Specifically, significant enhancement of the time delay in the innermost dipole photoionization channels near threshold is found, owing to the presence of the Coulomb confined resonances (CRs). Moreover, it is shown that interchannel coupling of the inner-shell Coulomb CRs with outer-shell photoionization channels results in resonantly enhanced time delay in the release of the outer-shell photoelectron well above, several hundreds eV, the outer-shell thresholds. It is also demonstrated that, and explained why, photoionization cross sections of the innermost subshells as well as outer subshells (near the inner-subshell threshold) depends only very weakly on the anion charge q , but the dependence of the corresponding time delays on q can be significant. Furthermore, Coulomb CRs are found to emerge in the innermost quadrupole photoionization channels as well, thereby causing considerable time delay in the quadrupole photoemission. These findings are illustrated in calculations of the photoionization of inner and outer subshells of the endohedral anions Ne@C60-1 and Ne@C60-5 that were chosen as case studies.

  7. Stoichiometry of uranyl salophene anion complexes

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Ruel, Bianca H.M.; Engbersen, Johannes F.J.; Reinhoudt, David

    1998-01-01

    In PVC/NPOE ion-selective membranes of potentiometric sensors, the guest-host stoichiometry of the anion complex of H2PO4 - and F- selective uranyl salophene derivatives is 2:1. This stoichiometry is different from the stoichiometry observed in DMSO solution (1H NMR) or solid state (X-ray crystal st

  8. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

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

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...... alkali metal chlorides as well as BaCl2, NaBr and (CH3CH2CH2)(4)NBr were used to investigate the effects of both the ionic charge, size and shape. In 1: 1 electrolytes using small ions only three peaks are present: a sharp cathodic peak at ca. - 0.6 V vs, SCE representing both the insertion of cations...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  9. Synthesis of azaphenanthridines via anionic ring closure

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  10. Donnan Membrane Technique (DMT) for Anion Measurement

    NARCIS (Netherlands)

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

    2010-01-01

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

  11. Neutral Resonant Ionization in Hydrogen Anion Production

    Science.gov (United States)

    Vogel, John

    2013-09-01

    Dissociative ionization of molecules causes gas phase H- but fails to explain anion intensity. Atomic collisions on surfaces with reduced work function give anions, but also fail to explain intensity, lowered electron density, and diagnostics. Neutral resonant ionization of H(2s) atoms to ion pairs is here predicted with a very high cross section. H(2s,p) atoms are resonant with numerous short-lived excited states (``resonances'') of H- as well as the putative doubly-excited stable state of H- which resists production by other means. This state decays through 1Σu+ (2s σu2) to a singly excited ion pair, leaving both proton and anion with 3.8 eV energy. H(2s,p) atoms arise from dissociative recombination of trihydrogen ion (H3+)which dominates ion content of hydrogen plasmas. Initial H(2s,p) are resonantly produced by ground state Cs atoms or excited Ar, Kr, and Xe atoms, but these initiators are not needed to sustain anion production. This theory may explain the intense ion source at Cal Tech that produced 1.5 mA/cm2 H3 in the mid-1980's (1). A full CRM calculation is not complete, but equilibrium calculations suggest that >1 mA/cm2 H- may be predicted.

  12. Stoichiometry of uranyl salophene anion complexes

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruel, Bianca H.M.; Engbersen, Johan F.J.; Reinhoudt, David N.

    1998-01-01

    In PVC/NPOE ion-selective membranes of potentiometric sensors, the guest-host stoichiometry of the anion complex of H2PO4 - and F- selective uranyl salophene derivatives is 2:1. This stoichiometry is different from the stoichiometry observed in DMSO solution (1H NMR) or solid state (X-ray crystal st

  13. Anionic phospholipids modulate peptide insertion into membranes.

    Science.gov (United States)

    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

  14. Anion-π interactions involving [MX(n)](m-) anions: a comprehensive theoretical study.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jonathan L. Sessler

    2007-09-21

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

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

    Science.gov (United States)

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

    2014-07-01

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

  17. Three hydroxy aurone compounds as chemosensors for cyanide anions.

    Science.gov (United States)

    Chen, Huihui; Sun, Yunhui; Zhou, Chuanjian; Cao, Duxia; Liu, Zhiqiang; Ma, Lin

    2013-12-01

    Three new 4-hydroxy aurone compounds 1-3 with dimethylamino (1), bromine (2) and cyano (3) as terminal group have been synthesized. Their photophysical properties as well as recognition properties for cyanide anions in acetonitrile and aqueous solution have also been examined. These compounds exhibit remarkable response to cyanide anions with obvious color and fluorescence change owing to hydrogen bonding reaction between cyanide anions and the O-H moiety of the sensors, which allows naked eye detection of cyanide anions.

  18. Color Responses of a Tripodal Colorimetric Sensor toward Anions

    Institute of Scientific and Technical Information of China (English)

    WEI Lan-Hua; HE Yong-Bing; WU Jin-Long; QIN Hai-Juan; XU Kuo-Xi; MENG Ling-Zhi

    2005-01-01

    A thiourea-based tripodal colorimetric anion sensor was synthesized. Its binding abilities with AcO- and halide anions in DMSO were studied by UV-Vis spectra. The sensor showed different color responses to these anions. The association constants and different stoichiometries were deduced by nonlinear least-square curve fitting or linear fitting.

  19. Electron anions and the glass transition temperature

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Specific anion effects in Artemia salina.

    Science.gov (United States)

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

    2015-09-01

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

  1. Gas-Phase Reactivity of Microsolvated Anions

    DEFF Research Database (Denmark)

    Thomsen, Ditte Linde

    Gas-phase studies of ion-molecule reactions shed light on the intrinsic factors that govern reactivity; and even solvent effects can be examined in the gasphase environment by employing microsolvated ions. An area that has received considerable attention with regard to the interplay between...... intrinsic factors and solvent effects is the enhanced reactivity of α-nucleophiles – nucleophiles with a lone-pair adjacent to the attacking site – referred to as the α-effect. This thesis concerns the reactivity of microsolvated anions and in particular how the presence of a single solvent molecule affects...... the gas-phase α-effect. The experimental studies are performed by means of the flowing after glow selected ion flow tube technique, and these are supplemented by electronic structure calculations. The α-nucleophile employed is the microsolvated hydrogen peroxide anion whose reactivity is compared...

  2. Stability and Characteristics of the Halogen Bonding Interaction in an Anion-Anion Complex: A Computational Chemistry Study.

    Science.gov (United States)

    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.

  3. Politseiuuringud kooskõlastamisele / Liivia Anion

    Index Scriptorium Estoniae

    Anion, Liivia

    2003-01-01

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

  4. Lowest autodetachment state of the water anion

    Science.gov (United States)

    Houfek, Karel; Čížek, Martin

    2016-05-01

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

  5. Dual role of LRRC8A-containing transporters on cisplatin resistance in human ovarian cancer cells

    DEFF Research Database (Denmark)

    Sørensen, Belinda Halling; Dam, Celina Støving; Stürup, Stefan;

    2016-01-01

    component of volume sensitive channels for organic osmolytes (VSOAC) and volume regulated anion channels (VRAC), which are activated during the apoptotic process. Here we illustrate that cisplatin resistance in human ovarian cancer cells (A2780) correlates with a reduced expression of LRRC8A and copper...... transporter receptor 1 (CTR1), as well as a concomitant increased expression of copper-transporting P-type ATPases (ATP7A/ATP7B). We also find that cisplatin (Pt) accumulation correlates with LRRC8A protein expression and channel activity, i.e., the cellular Pt content is high when VSOAC is activated...... expression in cisplatin-resistant A2780 cells ensures cell survival through limitation in cisplatin accumulation and a concomitant reduction in osmolytes loss via VSOAC/VRAC and hence instigation of the apoptotic process....

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

    OpenAIRE

    Srivastava, Ambrish Kumar; Misra, Neeraj

    2016-01-01

    The electrolytes used in Lithium Ion Batteries (LIBs) such as LiBF4, LiPF6 etc. are Li-salts of some complex anions, BF4-, PF6- etc. The investigation shows that the vertical detachment energy (VDE) of these anions exceeds to that of halogen, and therefore they behave as superhalogen anions. Consequently, it might be possible to design new electrolytic salts using other superhalogen anions. We have explored this possibility using Li-salts of various superhalogen anions such as BO2-, AlH4-, Ti...

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

    Science.gov (United States)

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

    2010-04-01

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

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

    Science.gov (United States)

    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.

  9. Anion conductance of the human red cell is carried by a maxi-anion channel

    DEFF Research Database (Denmark)

    Glogowska, Edyta; Dyrda, Agnieszka; Cueff, Anne

    2010-01-01

    played by serum in the recruitment of multiple new conductance levels showing very complex kinetics and gating properties upon serum addition. These channels, which seem to be dormant under normal physiological conditions, are potentially activable and could confer a far higher anion conductance...... channels proper has never been clarified, and the informations obtained by different groups of electrophysiologists are rather badly matched. This study, using the cell-attached configuration of the patch-clamp technique, rationalizes and explains earlier confusing results by demonstrating...... that the diversity of anionic channel activities recorded in human erythrocytes corresponds to different kinetic modalities of a unique type of maxi-anion channel with multiple conductance levels and probably multiple gating properties and pharmacology, depending on conditions. It demonstrates the role of activator...

  10. Expanded Porphyrin-Anion Supramolecular Assemblies: Environmentally Responsive Sensors for Organic Solvents and Anions.

    Science.gov (United States)

    Zhang, Zhan; Kim, Dong Sub; Lin, Chung-Yon; Zhang, Huacheng; Lammer, Aaron D; Lynch, Vincent M; Popov, Ilya; Miljanić, Ognjen Š; Anslyn, Eric V; Sessler, Jonathan L

    2015-06-24

    Porphyrins have been used frequently to construct supramolecular assemblies. In contrast, noncovalent ensembles derived from expanded porphyrins, larger congeners of naturally occurring tetrapyrrole macrocycles, are all but unknown. Here we report a series of expanded porphyrin-anion supramolecular assemblies. These systems display unique environmentally responsive behavior. Addition of polar organic solvents or common anions to the ensembles leads to either a visible color change, a change in the fluorescence emission features, or differences in solubility. The actual response, which could be followed easily by the naked eye, was found to depend on the specifics of the assembly, as well as the choice of analyte. Using the ensembles of this study, it proved possible to differentiate between common solvents, such as diethyl ether, THF, ethyl acetate, acetone, alcohol, acetonitrile, DMF, and DMSO, identify complex solvent systems, as well as distinguish between the fluoride, chloride, bromide, nitrate, and sulfate anions.

  11. Interaction of anions with substituted buckybowls. The anion's nature and solvent effects.

    Science.gov (United States)

    Campo-Cacharrón, Alba; Cabaleiro-Lago, Enrique M; González-Veloso, Iván; Rodríguez-Otero, Jesús

    2014-08-07

    Complexes formed by CN-substituted corannulene and sumanene with monovalent anions have been computationally studied to evaluate the effect of anion's nature and solvent upon the interaction. The results indicate that the most stable complex arrangement corresponds in all cases to the anion located by the center of the concave face of the bowl. All complexes are remarkably stable in the gas phase, with interaction energies ranging from -47 to -24 kcal/mol depending on the anion and the bowl considered. The order of stability for the different anion complexes in the gas phase is CO2H(-) > Cl(-) > Br(-) > NO3(-) ≫ ClO4(-) > BF4(-). Regarding the bowl employed, the intensity of the interaction is largest with the sumanene derivative substituted in the C-H aromatic groups. The weakest interactions are obtained with the sumanene derivative substituted in the CH2 groups, whereas complexes with the corannulene derivative give intermediate values. NO3(-) is oriented parallel to the bowl in the most stable complexes, whereas CO2H(-) prefers being oriented perpendicular to the bowl; ClO4(-) and BF4(-) arrange themselves with three bonds pointing to the bowl. These orientations are preferred on the basis of larger electrostatic and dispersion interactions. The preference of anions for the concave face of the bowl not only is mainly related to larger electrostatic interactions but also is because dispersion and induction are larger than in other arrangements considered. The presence of solvent modeled with a continuum model has a deep impact on the interaction energies already in solvents with low dielectric constant. All complexes remain stable, though energies in water hardly reach -7 kcal/mol. Br(-) complexes are the most stable in solvent, whereas CO2H(-) ones suffer a large penalty in solvent, becoming among the least stable complexes despite being the most stable in the gas phase.

  12. Maxi-anion channel as a candidate pathway for osmosensitive ATP release from mouse astrocytes in primary culture

    Institute of Scientific and Technical Information of China (English)

    Hong-Tao Liu; Abduqodir H Toychiev; Nobuyuki Takahashi; Ravshan Z Sabirov; Yasunobu Okada

    2008-01-01

    In the present study,we aimed to evaluate the pathways contributing to ATP release from mouse astrocytes during hypoosmotic stress.We first examined the expression of mRNAs for proteins constituting possible ATPreleasing pathways that have been suggested over the past several years.In RT-PCR analysis using both control and osmotically swollen astrocytes,amplification of cDNA fragments of expected size was seen for connexins (Cx32,Cx37,Cx43),pannexin 1 (Pxl),the P2X7 receptor,MRP1 and MDRI,but not CFTR.Inhibitors of exocytotie vesicular release,gap junction hemi-channels,CFTR,MRPI,MDR1,the P2X7 receptor,and volume-sensitive outwardly rectifying chloride channels had no significant effects on the massive ATP release from astrocytes.In contrast,the hypotonicity-induced ATP release from astrocytes was most effectively inhibited by gadolinium release from several other cell types.Thus,we propose that the maxi-anion channel constitutes a major pathway for swelling-induced ATP release from cultured mouse astrocytes as well.

  13. Organic superconductors with an incommensurate anion structure

    Directory of Open Access Journals (Sweden)

    Tadashi Kawamoto and Kazuo Takimiya

    2009-01-01

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

  14. On the electronic structure of fullerene anions

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-02-03

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

  15. Probes for anionic cell surface detection

    Science.gov (United States)

    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.

  16. Electroculture for crop enhancement by air anions

    Science.gov (United States)

    Pohl, H. A.; Todd, G. W.

    1981-12-01

    Electroculture, the practice of applying strong electric fields or other sources of small air ions to growing plants, has potential to markedly increase crop production and to speed crop growth. The considerable evidence for its effectiveness, and the studies of the mechanisms for its actions are discussed. A mild current of air anions (4 pA/cm2) stimulates bean crop growth and also earlier blossoming and increased growth in the annual, Exacum affine (Persian violet), as well as in seedling geraniums. The present results would indicate that the growing period required until the plants reach a saleable stage of maturity can be shortened by about two weeks under greenhouse conditions.

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

    Science.gov (United States)

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

    2004-11-01

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

  18. Osmolyte regulation by TonEBP/NFAT5 during anoxia-recovery and dehydration–rehydration stresses in the freeze-tolerant wood frog (Rana sylvatica)

    Science.gov (United States)

    Al-attar, Rasha; Zhang, Yichi

    2017-01-01

    Background The wood frog, Rana sylvatica, tolerates freezing as a means of winter survival. Freezing is considered to be an ischemic/anoxic event in which oxygen delivery is significantly impaired. In addition, cellular dehydration occurs during freezing because water is lost to extracellular compartments in order to promote freezing. In order to prevent severe cell shrinkage and cell death, it is important for the wood frog to have adaptive mechanisms for osmoregulation. One important mechanism of cellular osmoregulation occurs through the cellular uptake/production of organic osmolytes like sorbitol, betaine, and myo-inositol. Betaine and myo-inositol are transported by the proteins BGT-1 and SMIT, respectively. Sorbitol on the other hand, is synthesized inside the cell by the enzyme aldose reductase. These three proteins are regulated at the transcriptional level by the transcription factor, NFAT5/TonEBP. Therefore, the objective of this study was to elucidate the role of NFAT5/TonEBP in regulating BGT-1, SMIT, and aldose reductase, during dehydration and anoxia in the wood frog muscle, liver, and kidney tissues. Methods Wood frogs were subjected to 24 h anoxia-4 h recovery and 40% dehydration-full rehydration experiments. Protein levels of NFAT5, BGT-1, SMIT, and aldose reductase were studied using immunoblotting in muscle, liver, and kidney tissues. Results Immunoblotting results demonstrated downregulations in NFAT5 protein levels in both liver and kidney tissues during anoxia (decreases by 41% and 44% relative to control for liver and kidney, respectively). Aldose reductase protein levels also decreased in both muscle and kidney tissues during anoxia (by 37% and 30% for muscle and kidney, respectively). On the other hand, BGT-1 levels increased during anoxia in muscle (0.9-fold compared to control) and kidney (1.1-fold). Under 40% dehydration, NFAT5 levels decreased in liver by 53%. Aldose reductase levels also decreased by 42% in dehydrated muscle, and by

  19. Osmolyte regulation by TonEBP/NFAT5 during anoxia-recovery and dehydration–rehydration stresses in the freeze-tolerant wood frog (Rana sylvatica

    Directory of Open Access Journals (Sweden)

    Rasha Al-attar

    2017-01-01

    Full Text Available Background The wood frog, Rana sylvatica, tolerates freezing as a means of winter survival. Freezing is considered to be an ischemic/anoxic event in which oxygen delivery is significantly impaired. In addition, cellular dehydration occurs during freezing because water is lost to extracellular compartments in order to promote freezing. In order to prevent severe cell shrinkage and cell death, it is important for the wood frog to have adaptive mechanisms for osmoregulation. One important mechanism of cellular osmoregulation occurs through the cellular uptake/production of organic osmolytes like sorbitol, betaine, and myo-inositol. Betaine and myo-inositol are transported by the proteins BGT-1 and SMIT, respectively. Sorbitol on the other hand, is synthesized inside the cell by the enzyme aldose reductase. These three proteins are regulated at the transcriptional level by the transcription factor, NFAT5/TonEBP. Therefore, the objective of this study was to elucidate the role of NFAT5/TonEBP in regulating BGT-1, SMIT, and aldose reductase, during dehydration and anoxia in the wood frog muscle, liver, and kidney tissues. Methods Wood frogs were subjected to 24 h anoxia-4 h recovery and 40% dehydration-full rehydration experiments. Protein levels of NFAT5, BGT-1, SMIT, and aldose reductase were studied using immunoblotting in muscle, liver, and kidney tissues. Results Immunoblotting results demonstrated downregulations in NFAT5 protein levels in both liver and kidney tissues during anoxia (decreases by 41% and 44% relative to control for liver and kidney, respectively. Aldose reductase protein levels also decreased in both muscle and kidney tissues during anoxia (by 37% and 30% for muscle and kidney, respectively. On the other hand, BGT-1 levels increased during anoxia in muscle (0.9-fold compared to control and kidney (1.1-fold. Under 40% dehydration, NFAT5 levels decreased in liver by 53%. Aldose reductase levels also decreased by 42% in

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-28

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

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

    Science.gov (United States)

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

    Science.gov (United States)

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

    2013-12-09

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

  3. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

    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.

  4. Isatin phenylhydrazones: anion enhanced photochromic behaviour.

    Science.gov (United States)

    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.

  5. Advancements in Anion Exchange Membrane Cations

    Energy Technology Data Exchange (ETDEWEB)

    Sturgeon, Matthew R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Long, Hai [National Renewable Energy Lab. (NREL), Golden, CO (United States); Park, Andrew M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pivovar, Bryan S. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  6. Isobar Separator for Anions: Current status

    Energy Technology Data Exchange (ETDEWEB)

    Alary, Jean-François, E-mail: alaryjf@isobarex.ca [Isobarex Corp., 32 Nixon Road Unit #1, Bolton, ON L7E 1W2 (Canada); Javahery, Gholamreza [IONICS Mass Spectrometry, 32 Nixon Road Unit #1, Bolton, ON L7E 1W2 (Canada); Kieser, William; Zhao, Xiao-Lei [Andre E. Lalonde Accelerator Mass Spectrometry Laboratory, Advanced Research Complex, University of Ottawa, 25 Templeton Street, Ottawa, ON K1N 6N5 (Canada); Litherland, Albert [IsoTrace Laboratory, Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3B1 (Canada); Cousins, Lisa [IONICS Mass Spectrometry, 32 Nixon Road Unit #1, Bolton, ON L7E 1W2 (Canada); Charles, Christopher [Andre E. Lalonde Accelerator Mass Spectrometry Laboratory, Advanced Research Complex, University of Ottawa, 25 Templeton Street, Ottawa, ON K1N 6N5 (Canada)

    2015-10-15

    The Isobar Separator for Anions (ISA) is an emerging separation technique of isobars applied first to the selective removal of {sup 36}S from {sup 36}Cl, 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.

  7. Modeling Carbon Chain Anions in L1527

    CERN Document Server

    Harada, Nanase

    2008-01-01

    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 Cn-, 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 ~5000 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-...

  8. Ion-selective electrode and anion gap range: What should the anion gap be?

    Directory of Open Access Journals (Sweden)

    Sadjadi SA

    2013-06-01

    Full Text Available Seyed-Ali Sadjadi, Rendell Manalo, Navin Jaipaul, James McMillan Jerry L Pettis Memorial Veterans Medical Center, Loma Linda University School of Medicine, Loma Linda, CA, USA Background: Using flame photometry technique in the 1970s, the normal value of anion gap (AG was determined to be 12 ± 4 meq/L. However, with introduction of the autoanalyzers using an ion-selective electrode (ISE, the anion gap value has fallen to lower levels. Methods: A retrospective study of US veterans from a single medical center was performed to determine the value of the anion gap in subjects with normal renal function and normal serum albumin and in patients with lactic acidosis and end-stage renal disease on dialysis. Results: In 409 patients with an estimated glomerular filtration rate ≥60 mL/min/1.73 m2 body surface area and serum albumin ≥4 g/dL, the mean AG was 7.2 ± 2 (range 3–11 meq/L. In 299 patients with lactic acidosis (lactate level ≥4 meq/L and 68 patients with end-stage renal disease on dialysis, the mean AG was 12.5 meq/L and 12.4 meq/L, respectively. A value <2 meq/L should be considered a low anion gap and a possible clue to drug intoxication and paraproteinemic disorders. Conclusion: With the advent of ISE for measurement of analytes, the value of the anion gap has fallen. Physicians need to be aware of the normal AG value in their respective institutions, and laboratories need to have an established value for AG based on the type of instrument they are using. Keywords: acidosis, electrolytes, ESRD

  9. A model for underpotential deposition in the presence of anions

    Science.gov (United States)

    Giménez, M. C.; Ramirez-Pastor, A. J.; Leiva, E. P. M.

    2010-05-01

    A simple model to study the effect of on top coadsorption of anions in underpotential deposition is formulated. It considers a lattice-gas model with pair potential interactions between nearest neighbors. As test system, the electrodeposition of silver on gold is studied by means of grand canonical Monte Carlo simulations. The influence of anions on the adsorption isotherms is analyzed. It is found that as the interaction between silver atoms and anions increases, the monolayer adsorbs at more negative chemical potentials. For large interactions between silver atoms and anions, a expanded structure occurs for the silver monolayer.

  10. A colorimetric tetrathiafulvalene-calix 4 pyrrole anion sensor

    DEFF Research Database (Denmark)

    Nielsen, K. A.

    2012-01-01

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

  11. Hydrazone derivatives appended to diphenylphosphine oxide as anion sensors

    Indian Academy of Sciences (India)

    MARUTHAI KUMARAVEL; JOEL T MAGUE; MARAVANJI S BALAKRISHNA

    2017-04-01

    Phosphine substituted hydrazones with or without nitro substituents were synthesized and characterized by multinuclear NMR, FT-IR, UV-Vis spectroscopy and single crystal X-ray diffraction. The anion recognition properties of phosphine oxides {Ph₂P(O)C₆H₄CHNNHPh} (2) and {Ph₂P(O)C₆H₄CHNNHC₆H₃ (2,4-NO₂) ₂} (4) with anions (F⁻, Cl⁻, Br⁻, I⁻, CH₃COO⁻ and H₂PO⁻ ₄ ) were investigated. The selectivity towards these anions is attributed to the hydrogen bonding capability of the NH bond. Competitive titrations have shown that the binding ability of fluoride with 4 is not influenced by the presence of other anions.

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

    Science.gov (United States)

    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.

  13. Once upon Anion: A Tale of Photodetachment

    Science.gov (United States)

    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. Anion permselective membrane. [For redox fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, S.S.; Hodgdon, R.B.

    1978-01-01

    Experimental anion permeselective membranes were improved and characterized for use as separators in a chemical redox, power storage cell being developed at the NASA Lewis Research Center. The goal of minimal Fe/sup +3/ ion transfer was achieved for each candidate membrane system. Minimal membrane resistivity was demonstrated by reduction of film thickness using synthetic backing materials but usefulness of thin membranes was limited by the scarcity of compatible fabrics. The most durable and useful backing fabrics were modacrylics. One membrane, a copolymer of 4 vinylpyridine and vinyl benzylchloride was outstanding in overall electrochemical and physical properties. Long term (1000 hrs) membrane chemical and thermal durability in redox environment was shown by three candidate polymers and two membranes. The remainder had good durability at ambient temperature. Manufacturing capability was demonstrated for large scale production of membrane sheets 5.5 ft/sup 2/ in area for two candidate systems.

  15. Structural evolution of small ruthenium cluster anions

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-14

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

  16. Advanced polymer chemistry of organometallic anions

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-11-01

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

  17. Adsorption of an anionic dispersant on lignite

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, R.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Dept. of Chemical Engineering, Chemical & Metallurgical Engineering Faculty

    2001-12-01

    Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples was investigated. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N{sub 2}5 as a wetting agent, a sodium lauryl ether sulfate, have been used.

  18. Anion channelrhodopsins for inhibitory cardiac optogenetics

    Science.gov (United States)

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

    2016-01-01

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

  19. Diffuse neutron scattering from anion-excess strontium chloride

    DEFF Research Database (Denmark)

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

    1992-01-01

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

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

    DEFF Research Database (Denmark)

    Holcman, Jerzy; Sehested, Knud

    1975-01-01

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

  1. Regulation of organic anion transport in the liver

    NARCIS (Netherlands)

    Roelofsen, H; Jansen, PLM

    1997-01-01

    In several liver diseases the biliary transport is disturbed, resulting in, for example, jaundice and cholestasis. Many of these symptoms can be attributed to altered regulation of hepatic transporters. Organic anion transport, mediated by the canalicular multispecific organic anion transporter (cmo

  2. Electron transfer from alpha-keggin anions to dioxygen

    Science.gov (United States)

    Yurii V. Geletii; Rajai H. Atalla; Craig L. Hill; Ira A. Weinstock

    2004-01-01

    Polyoxometalates (POMs), of which alpha-Keggin anions are representative, are a diverse and rapidly growing class of water-soluble cluster-anion structures with applications ranging from molecular catalysis to materials. [1] POMs are inexpensive, minimally or non-toxic, negatively charged clusters comprised of early transition-metals, usually in their do electronic...

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    Sprik, M.

    1991-01-01

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

  5. Removal of anionic reactive dyes from water using anion exchange membranes as adsorbers.

    Science.gov (United States)

    Liu, Chia-Hung; Wu, Jeng-Shiou; Chiu, Hsin-Chieh; Suen, Shing-Yi; Chu, Khim Hoong

    2007-04-01

    Two commercial anion exchange membranes, strong basic (SB6407) and weak basic (DE81), were evaluated for the removal of anionic reactive dyes, Cibacron blue 3GA (three sulfonic acid groups per dye molecule) and Cibacron red 3BA (four sulfonic acid groups per dye molecule), from water in this study. The adsorption isotherm results show that the Langmuir maximum adsorption capacities of Cibacron blue 3GA (31.5mg/cm(3) for SB6407 and 25.5mg/cm(3) for DE81) were greater than those of Cibacron red 3BA (24.5mg/cm(3) for SB6407 and 18.5mg/cm(3) for DE81). For each reactive dye, the capacity for SB6407 was higher than DE81 based on the same membrane volume. However, consideration of the number of ion exchange sites interacting with a dye molecule indicates that the DE81 results are close to the theoretical values while the SB6407 membrane had some unused binding sites. In addition, Cibacron red 3BA demonstrated faster and stronger binding with both anion exchange membranes than Cibacron blue 3GA. Both dyes could bind with strong basic SB6407 more quickly and stronger. In the batch desorption process, different desorption solutions were tested and the mixtures of salt, acid, or base in methanol solution (e.g. 1N KSCN in 60% methanol or 1N HCl in 60% methanol) achieved better performance. Finally, in the flow process with one piece of anion exchange membrane (initial dye concentration of 0.05g/L), SB6407 was found superior to DE81 in dye recovery and both membranes retained their original uptake capacities over three cycles of adsorption, washing, and desorption.

  6. Nucleophilic reactivities of the anions of nucleobases and their subunits.

    Science.gov (United States)

    Breugst, Martin; Corral Bautista, Francisco; Mayr, Herbert

    2012-01-02

    The kinetics of the reactions of different heterocyclic anions derived from imidazoles, purines, pyrimidines, and related compounds with benzhydrylium ions and structurally related quinone methides have been studied in DMSO and water. The second-order rate constants (log k(2)) correlated linearly with the electrophilicity parameters E of the electrophiles according to the correlation log k(2) = s(N)(N+E) (H. Mayr, M. Patz, Angew. Chem. 1994, 106, 990-1010; Angew. Chem. Int. Ed. Engl. 1994, 33, 938-957) allowing us to determine the nucleophilicity parameters N and s(N) for these anions. In DMSO, the reactivities of these heterocyclic anions vary by more than six orders of magnitude and are comparable to carbanions, amide and imide anions, or amines. The azole anions are generally four to five orders of magnitude more reactive than their conjugate acids.

  7. Coumarin amide derivatives as fluorescence chemosensors for cyanide anions

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  8. Anionic clusters in dusty hydrocarbon and silane plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hollenstein, C.; Schwarzenbach, W.; Howling, A.A.; Courteille, C.; Dorier, J.L.; Sansonnens, L. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1995-10-01

    Measurements of anions and cations are reported for hydrocarbon and silane rf capacitive glow discharges. Series of anions were observed by quadrupole mass spectrometry using power-modulated plasmas and their structures are interpreted from the form of the mass spectra. Various experiments in silane plasmas show that anion confinement results in particles and conversely, anion de-trapping can inhibit particle formation. In contrast, the polymerized neutral flux magnitudes, mass spectra and dynamics are independent of the powder formation. Powder is known to form readily in deposition plasmas containing electronegative free radicals, and the general role of anions in particle formation is discussed in the light of these experiments. (author) 6 figs., 21 refs.

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

    Science.gov (United States)

    Song, Hyun-Ouk; Ryu, Jae-Sook

    2013-08-01

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

  10. Study on the Anion Recognition Properties of Synthesized Receptors (Ⅲ): Convenient Synthesis and Anion Recognition Property of Bisthiosemicarbazone Derivative

    Institute of Scientific and Technical Information of China (English)

    ZHANG You-Ming; XU Wei-Xia; YAO Hong; WEI Tai-Bao

    2006-01-01

    A new series of bisthiosemicarbazone derivative receptors (1, 2 and 3) have been synthesized by simple steps in good yields. Their anion recognition properties were studied by UV-Vis and 1H NMR spectroscopy. The result showed that the receptors 1, 2 and 3 all had a better selectivity to F-, CH3COO- and H2PO4-, but no evident binding with Cl-, Br-, I-, NO3- and HSO4. Upon addition of the three anions to the receptors in DMSO, the solution acquired a color change from colorless to dark yellow that can be observed by the naked-eyes, thus the receptors can act as fluoride ion sensors even in the presence of other halide ions. The data showed that it was regular that the three receptors had different binding ability with the three anions. For the same anion, the association conformed through hydrogen bonding interactions between compound 1, 2 or 3 and anions.

  11. Gallium based low-interaction anions

    Science.gov (United States)

    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.

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

    CERN Document Server

    Srivastava, Ambrish Kumar

    2016-01-01

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

  13. Pyruvate anions neutralize peritoneal dialysate cytotoxicity.

    Science.gov (United States)

    Mahiout, A; Brunkhorst, R

    1995-01-01

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

  14. Antimicrobial Ionic Liquids with Fumarate Anion

    Directory of Open Access Journals (Sweden)

    Biyan He

    2013-01-01

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

  15. Anionic peroxidase production by Arnebia euchroma callus.

    Science.gov (United States)

    Farhadi, Sahar; Haghbeen, Kamahldin; Marefatjo, Mohammad-Javad; Hoor, Marjan Ghiyami; Zahiri, Hossein Shahbani; Rahimi, Karim

    2011-01-01

    Arnebia euchroma callus, obtained from the root cell culture of an Iranian native specimen, has gained a doubling time of 63 H after regular subculturing on Linsmaier-Skoog (LS) medium containing sugar (50 g/L), 2,4-dichlorophenoxyacetic acid (10(-6) M), and kinetin (10(-5) M) under darkness at 25°C. Despite the observed somaclonal variations, peroxidase production by the A. euchroma calli has been stable over 4 years under the aforementioned conditions. Isoelectric focusing experiments revealed that the partially purified A. euchroma peroxidases (AePoxs) are mainly anionic with pI values of about 5.5 and 6.6. AePox reaches its optimal activity at 55°C and pH 7.5. Results of the various kinetic studies suggest that AePox belongs to the type III plant peroxidases with no activity for the oxidation of 3-indoleacetic acid, but seems to play a role in the lignin biosynthesis and H(2) O(2) regulation during the proliferation of the A. euchroma cells on LS medium. Comparing the biochemical properties of AePox with horseradish peroxidase and in view of the ease of solid cell culture, the A. euchroma callus could be considered as a source of plant peroxidase for some biotechnological applications. Copyright © 2011 International Union of Biochemistry and Molecular Biology, Inc.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-01

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

  17. A Quick Reference on High Anion Gap Metabolic Acidosis.

    Science.gov (United States)

    Funes, Silvia; de Morais, Helio Autran

    2017-03-01

    High anion gap (AG) metabolic acidoses can be identified by a decrease in pH, decrease in HCO3(-) or base excess, and an increased AG. The AG represents the difference between unmeasured cations and unmeasured anions; it increases secondary to the accumulation of anions other than bicarbonate and chloride. The most common causes of high AG acidosis are renal failure, diabetic ketoacidosis, and lactic acidosis. Severe increases in concentration of phosphorus can cause hyperphosphatemic acidosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. The role of lipophilicity in transmembrane anion transport

    NARCIS (Netherlands)

    Saggiomo, Vittorio; Otto, Sijbren; Marques, Igor; Felix, Vitor; Torroba, Tomas; Quesada, Roberto

    2012-01-01

    The transmembrane anion transport activity of a series of synthetic molecules inspired by the structure of tambjamine alkaloids can be tuned by varying the lipophilicity of the receptor, with carriers within a certain log P range performing best.

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

    Science.gov (United States)

    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 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.

  20. Two benzoyl coumarin amide fluorescence chemosensors for cyanide anions

    Science.gov (United States)

    Wang, Zian; Wu, Qianqian; Li, Jiale; Qiu, Shuang; Cao, Duxia; Xu, Yongxiao; Liu, Zhiqiang; Yu, Xueying; Sun, Yatong

    2017-08-01

    Two new benzoyl coumarin amide derivatives with ortho hydroxyl benzoyl as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions in acetonitrile have also been examined. The influence of electron donating diethylamino group in coumarin ring and hydroxyl in benzoyl group on recognition properties was explored. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectral change and high sensitivity. The import of diethylamine group increases smartly the absorption ability and fluorescence intensity of the compound, which allows the recognition for cyanide anions can be observed by naked eyes. The in situ hydrogen nuclear magnetic resonance spectra combining photophysical properties change and job's plot data confirm that Michael addition between the chemosensors and cyanide anions occurs. Molecular conjugation is interrupted, which leads to fluorescence quenching. At the same time, there is a certain extent hydrogen bond reaction between cyanide and hydroxyl group in the compounds, which is beneficial to the recognition.

  1. Detection of cyanide anion by zinc porphyrin-spiropyran dyad

    Energy Technology Data Exchange (ETDEWEB)

    Kho, Young Min; Hur, Dae Young; Shin, Eun Ju [Dept. of Chemistry, Sunchon National University, Suncheon (Korea, Republic of)

    2016-10-15

    Versatile methods of the sensitive and selective detection for cyanide anion to monitor toxic cyanide have been developed. These include colorimetric, colorimetric, chromatographic, and electrochemical analyses. Among those methods for cyanide detection, optical methods based on absorption and fluorescence spectroscopy are relatively simple, inexpensive, and sensitive. A number of organic sensors for cyanide anion have been designed and synthesized. Absorption and/or fluorescence spectra of these sensors are changed by forming coordination complex or bonding covalently with cyanide. Compared with other anions, cyanide anion has some characteristic properties, such as its strong nucleophilicity and high binding affinity toward metal ions, and is superior and useful for the development of the sensors. Both covalent bond-based sensors and coordination complex-based sensors have been developed for cyanide detection. The results indicate that ZnP-SP plays a role as a CN{sup -} selective, colorimetric sensor either without or with UV irradiation.

  2. Adsorption of inorganic anionic contaminants on surfactant modified minerals

    Directory of Open Access Journals (Sweden)

    MAGDALENA TOMASEVIC-CANOVIC

    2003-11-01

    Full Text Available Organo-mineral complexes were obtained by treatment of aluminosilicate minerals (zeolite, bentonite and diatomaceous earth with a primary amine (oleylamine and an alkyl ammonium salt (stearyldimethylbenzyl ammonium chloride. The modification of the zeolite surface was carried out in two steps. The first step was treatment of the zeolite with 2 M HCl. This acid treatment of the zeolite increased its affinity for neutral molecules such as surface-active amines. The second step of the modification was the adsorption of oleylamine on the acid treated zeolite. Four types of organo-mineral complexes were prepared and their anion adsorption properties were compared to those of organo-zeolite. The adsorption of sulphate, bichromate and dihydrogenphosphate anions on the organo-mineral complexes was investigated. The anion adsorption measurements showed that the most efficient adsorbent for anion water pollutants was the primary amine modified H+-form zeolite.

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

    DEFF Research Database (Denmark)

    Novak, I; Young, J A

    1986-01-01

    Cholinergically stimulated Cl and HCO3 transport in perfused rabbit mandibular glands has been studied with extracellular anion substitution and administration of transport inhibitors. In glands perfused with HCO3-free solutions, replacement of Cl with other anions supported secretion in the foll......Cholinergically stimulated Cl and HCO3 transport in perfused rabbit mandibular glands has been studied with extracellular anion substitution and administration of transport inhibitors. In glands perfused with HCO3-free solutions, replacement of Cl with other anions supported secretion...... stimulated secretion by about 30%, but when infused in addition to furosemide (0.1 mmol/l), it inhibited by about 20%. Amiloride (1.0 mmol/l) caused no inhibition. The results suggest that there are at least three distinct carriers in the rabbit mandibular gland. One is a furosemide-sensitive Na-coupled Cl...

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

    Indian Academy of Sciences (India)

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

    2005-03-01

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

  5. Intestinal transporters for endogenic and pharmaceutical organic anions

    DEFF Research Database (Denmark)

    Grandvuinet, Anne Sophie; Vestergaard, Henrik Tang; Rapin, Nicolas

    2012-01-01

    This review provides an overview of intestinal human transporters for organic anions and stresses the need for standardization of the various in-vitro methods presently employed in drug-drug interaction (DDI) investigations.......This review provides an overview of intestinal human transporters for organic anions and stresses the need for standardization of the various in-vitro methods presently employed in drug-drug interaction (DDI) investigations....

  6. Local impermeant anions establish the neuronal chloride concentration

    DEFF Research Database (Denmark)

    Glykys, J; Dzhala, V; Egawa, K

    2014-01-01

    , but accumulating evidence suggests factors other than the bulk concentrations of transported ions determine [Cl(-)](i). Measurement of [Cl(-)](i) in murine brain slice preparations expressing the transgenic fluorophore Clomeleon demonstrated that cytoplasmic impermeant anions ([A](i)) and polyanionic extracellular...... anions determine the homeostatic set point for [Cl(-)], and hence, neuronal volume and the polarity of local GABA(A)R signaling....

  7. Photoelectron spectroscopic study of carbon aluminum hydride cluster anions

    Science.gov (United States)

    Zhang, Xinxing; Wang, Haopeng; Ganteför, Gerd; Eichhorn, Bryan W.; Kiran, Boggavarapu; Bowen, Kit H.

    2016-10-01

    Numerous previously unknown carbon aluminum hydride cluster anions were generated in the gas phase, identified by time-of-flight mass spectrometry and characterized by anion photoelectron spectroscopy, revealing their electronic structure. Density functional theory calculations on the CAl5-9H- and CAl5-7H2- found that several of them possess unusually high carbon atom coordination numbers. These cluster compositions have potential as the basis for new energetic materials.

  8. Synthesis of Pyridoacridines through Anionic Cascade Ring Closure

    DEFF Research Database (Denmark)

    Petersen, I.N.; Kristensen, Jesper Langgaard

    2014-01-01

    A new synthesis of 13-deazaascididemin (AK-37) based on a recently developed anionic cascade ring closure is presented. Although the isolated yields are modest, the approach provides ready access to new substituted derivatives of 13-deazaascididemin. © Georg Thieme Verlag.......A new synthesis of 13-deazaascididemin (AK-37) based on a recently developed anionic cascade ring closure is presented. Although the isolated yields are modest, the approach provides ready access to new substituted derivatives of 13-deazaascididemin. © Georg Thieme Verlag....

  9. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

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

    2012-01-01

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

  10. Migration of Cations and Anions in Amorphous Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  11. Thin Robust Anion Exchange Membranes for Fuel Cell Applications

    Science.gov (United States)

    2014-01-01

    provide inexpensive compact power from a wider variety of fuels than is possible with a proton exchange membrane (PEM) fuel cell, has continued to...in aqueous solution. Interestingly though, while the proton transfer events in the anion exchange membrane are more frequent as would be ECS...release; distribution is unlimited. (Invited) Thin Robust Anion Exchange Membranes for Fuel Cell Applications The views, opinions and/or findings

  12. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

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

    2012-01-01

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

  13. Grain boundary mobility in anion doped MgO

    Science.gov (United States)

    Kapadia, C. M.; Leipold, M. H.

    1973-01-01

    Certain anions OH(-), F(-) and Gl(-) are shown to enhance grain growth in MgO. The magnitude of their effect decreases in the order in which the anions are listed and depends on their location (solid-solution, second phase) in the MgO lattice. As most anions exhibit relatively high vapor pressures at sintering temperatures, they retard densification and invariably promote residual porosity. The role of anions on grain growth rates was studied in relation to their effect on pore mobility and pore removal; the atomic process controlling the actual rates was determined from observed kinetics in conjunction with the microstructural features. With respect to controlling mechanisms, the effects of all anions are not the same. OH(-) and F(-) control behavior through creation of a defect structure and a grain boundary liquid phase while Cl(-) promotes matter transport within pores by evaporation-condensation. Studies on an additional anion, S to the minus 2nd power gave results which were no different from undoped MgO, possibly because of evaporative losses during hot pressing. Hence, the effect of sulphur is negligible or undetermined.

  14. Counterion-mediated pattern formation in membranes containing anionic lipids.

    Science.gov (United States)

    Slochower, David R; Wang, Yu-Hsiu; Tourdot, Richard W; Radhakrishnan, Ravi; Janmey, Paul A

    2014-06-01

    Most lipid components of cell membranes are either neutral, like cholesterol, or zwitterionic, like phosphatidylcholine and sphingomyelin. Very few lipids, such as sphingosine, are cationic at physiological pH. These generally interact only transiently with the lipid bilayer, and their synthetic analogs are often designed to destabilize the membrane for drug or DNA delivery. However, anionic lipids are common in both eukaryotic and prokaryotic cell membranes. The net charge per anionic phospholipid ranges from -1 for the most abundant anionic lipids such as phosphatidylserine, to near -7 for phosphatidylinositol 3,4,5 trisphosphate, although the effective charge depends on many environmental factors. Anionic phospholipids and other negatively charged lipids such as lipopolysaccharides are not randomly distributed in the lipid bilayer, but are highly restricted to specific leaflets of the bilayer and to regions near transmembrane proteins or other organized structures within the plane of the membrane. This review highlights some recent evidence that counterions, in the form of monovalent or divalent metal ions, polyamines, or cationic protein domains, have a large influence on the lateral distribution of anionic lipids within the membrane, and that lateral demixing of anionic lipids has effects on membrane curvature and protein function that are important for biological control. Copyright © 2014. Published by Elsevier B.V.

  15. Astronomical identification of CN-, the smallest observed molecular anion

    CERN Document Server

    Agundez, M; Guelin, M; Kahane, C; Roueff, E; Klos, J; Aoiz, F J; Lique, F; Marcelino, N; Goicoechea, J R; Garcia, M Gonzalez; Gottlieb, C A; McCarthy, M C; Thaddeus, P

    2010-01-01

    We present the first astronomical detection of a diatomic negative ion, the cyanide anion CN-, as well as quantum mechanical calculations of the excitation of this anion through collisions with para-H2. CN- is identified through the observation of the J = 2-1 and J = 3-2 rotational transitions in the C-star envelope IRC +10216 with the IRAM 30-m telescope. The U-shaped line profiles indicate that CN-, like the large anion C6H-, is formed in the outer regions of the envelope. Chemical and excitation model calculations suggest that this species forms from the reaction of large carbon anions with N atoms, rather than from the radiative attachment of an electron to CN, as is the case for large molecular anions. The unexpectedly large abundance derived for CN-, 0.25 % relative to CN, makes likely its detection in other astronomical sources. A parallel search for the small anion C2H- remains so far unconclusive, despite the previous tentative identification of the J = 1-0 rotational transition. The abundance of C2H...

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

    Institute of Scientific and Technical Information of China (English)

    Jia Jie Zhang; Hai Bao Zhu; Yan Zhu

    2012-01-01

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

  17. Thermally Cross-Linked Anion Exchange Membranes from Solvent Processable Isoprene Containing Ionomers

    Science.gov (United States)

    2015-01-15

    capacities (IECs). Solution cast membranes were thermally cross- linked to form anion exchange membranes. Cross-linking was achieved by taking advantage...distribution is unlimited. Thermally Cross-Linked Anion Exchange Membranes from Solvent Processable Isoprene Containing Ionomers The views...Box 12211 Research Triangle Park, NC 27709-2211 Anion Exchnage Membrane, Polymer synthesis, Morphology, Anion Conductivity REPORT DOCUMENTATION PAGE

  18. Tetravalent metal complexation by Keggin and lacunary phosphomolybdate anions.

    Science.gov (United States)

    Copping, Roy; Jonasson, Leif; Gaunt, Andrew J; Drennan, Dennis; Collison, David; Helliwell, Madeleine; Pirttijarvi, Ross J; Jones, Chris J; Huguet, Anne; Apperley, David C; Kaltsoyannis, Nikolas; May, Iain

    2008-07-07

    We report the synthesis, spectroscopic and structural characterization, and computational analysis of a series of phosphomolybdate complexes with tetravalent metal cations. The reaction between Ce (IV) and Th (IV) with phosphomolybdate at the optimum pH for the stabilization of the lacunary heteropolyoxometalate anion, [PMo 11O 39] (7-), results in the formation of compounds containing the anions [Ce(PMo 11O 39) 2] (10-) and [Th(PMo 11O 39) 2] (10-), respectively. Single crystal X-ray diffraction analysis was performed on salts of both species, Cs 10[Ce(PMo 11O 39) 2].20H 2O and (NH 4) 10[Th(PMo 11O 39) 2].22H 2O. In both anionic complexes the f-block metal cation is coordinated to the four unsaturated terminal lacunary site oxygens of each [PMo 11O 39] (7-) anion, yielding 8 coordinate sandwich complexes, analogous to previously prepared related complexes. Spectroscopic characterization points to the stability of these complexes in solution over a reasonably wide pH range. Density functional analysis suggests that the Ce-O bond strength in [Ce(PMo 11O 39) 2] (10-) is greater than the Th-O bond strength in [Th(PMo 11O 39) 2] (10-), with the dominant bonding interaction being ionic in both cases. In contrast, under similar reaction conditions, the dominant solid state Zr (IV) and Hf (IV) complexes formed contain the anions [Zr(PMo 12O 40)(PMo 11O 39)] (6-) and [Hf(PMo 12O 40)(PMo 11O 39)] (6-), respectively. In these complexes the central Group 4 d-block metal cations are coordinated to the four unsaturated terminal lacunary site oxygens of the [PMo 11O 39] (7-) ligand and to four bridging oxygens of a plenary Keggin anion, [PMo 12O 40] (3-). In addition, (NH 4) 5{Hf[PMo 12O 40][(NH 4)PMo 11O 39]}.23.5H 2O can be crystallized as a minor product. The structure of the anion, {Hf[PMo 12O 40][(NH 4)PMo 11O 39]} (5-), reveals coordination of the central Hf (IV) cation via four bridging oxygens on both the coordinated [PMo 11O 39] (7-) and [PMo 12O 40] (3-) anions

  19. In vitro characterization of a novel C,N-cyclometalated benzimidazole Ru(II) arene complex: stability, intracellular distribution and binding, effects on organic osmolyte homeostasis and induction of apoptosis.

    Science.gov (United States)

    Støving Dam, Celina; Alejo Perez Henarejos, Sergio; Tsolakou, Theodosia; Alexander Segato, Christian; Gammelgaard, Bente; Yellol, Gorakh S; Ruiz, José; Lambert, Ian Henry; Stürup, Stefan

    2015-05-01

    In the present work a novel C,N-cyclometalated benzimidazole Ru(ii) arene complex (GY34) was characterized by applying an alternative, diverse approach considering both chemical and biological aspects. RP-HPLC-ICP-MS and RP-HPLC-ESI-MS analysis proved that GY34 in both RPMI-1640 cell medium and ammonium acetate buffer was transformed into several subspecies and the importance of evaluating and controlling analyte stability throughout experiments was demonstrated. Applying a novel cell fractionation protocol GY34 was found to target cell nuclei and mitochondria in Ehrlich Lettré Ascites (ELA) cells, with the intracellular distribution depending on GY34 concentration in the cell medium during incubation. In ELA cells 96 ± 0.2% of cytosolic GY34 was bound to high-molecular species. Furthermore, using the tracer technique GY34 was found to reduce uptake and increase release of the organic osmolyte taurine in ELA cells, with innate resistance to Cisplatin and in A2780 human ovarian cancer cells, with acquired resistance to Cisplatin. Importantly, FACS analysis revealed that GY34 induced apoptosis in ELA cells. The present data suggest the potential of GY34 in overcoming Cisplatin resistance. The methodology applied can be used as a general protocol and an additional tool in the initial evaluation of novel metal-based drugs.

  20. Anion separation by selective crystallization of metal-organic frameworks.

    Science.gov (United States)

    Custelcean, Radu; Haverlock, Tamara J; Moyer, Bruce A

    2006-08-07

    A novel approach for the separation of anions from aqueous mixtures was demonstrated, which involves their selective crystallization with metal-organic frameworks (MOFs) containing urea functional groups. Self-assembly of Zn2+ with the N,N'-bis(m-pyridyl)urea (BPU) linker results in the formation of one-dimensional MOFs including various anions for charge balance, which interact to different extents with the zinc nodes and the urea hydrogen-bonding groups, depending on their coordinating abilities. Thus, Cl-, Br-, I-, and SO4(2-), in the presence of BPU and Zn2+, form MOFs from water, in which the anions coordinate the zinc and are hydrogen-bonded to the urea groups, whereas NO3- and ClO4- anions either do not form MOFs or form water-soluble discrete coordination complexes under the same conditions. X-ray diffraction, FTIR, and elemental analysis of the coordination polymers precipitated from aqueous mixtures containing equivalent amounts of these anions indicated total exclusion of the oxoanions and selective crystallization of the halides in the form of solid solutions with the general composition ZnCl(x)Br(y)I(z).BPU (x + y + z = 2), with an anti-Hofmeister selectivity. The concomitant inclusion of the halides in the same structural frameworks facilitates the rationalization of the observed selectivity on the basis of the diminishing interactions with the zinc and urea acidic centers in the MOFs when going from Cl- to I-, which correlates with decreasing anionic charge density in the same order. The overall crystal packing efficiency of the coordination frameworks, which ultimately determines their solubility, also plays an important role in the anion crystallization selectivity under thermodynamic equilibration.

  1. Discovery of Interstellar Anions in Cepheus and Auriga

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.; Buckle, J. V.; Walsh, C.

    2011-01-01

    We report the detection of microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H in the star-forming region LI251 A (in Cepheus), and the pre-stellar core LI512 (in Auriga). The carbon chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for LI5l2. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.

  2. Poly-anion production in Penning and RFQ ion traps

    Energy Technology Data Exchange (ETDEWEB)

    Bandelow, Steffi; Martinez, Franklin; Marx, Gerrit; Schweikhard, Lutz [Institute for Physics, Ernst-Moritz-Arndt University, 17487 Greifswald (Germany)

    2014-07-01

    The poly-anion production is being investigated in Penning and linear radio-frequency quadrupole (RFQ) traps at the ClusterTrap setup. The range of anionic charge states produced with the electron-bath technique in a Penning trap is restricted by the upper mass limit of this trap. By installation of a cylindrical Penning trap with a 12-Tesla superconducting magnet, the mass and thus cluster-size range is enhanced by a factor of 20 compared to the previously used hyperbolic 5-Tesla Penning trap. For first experimental tests with the 12-Tesla cylindrical Penning trap, gold cluster mono-anions Au{sup n-1}, n=330-350, have been exposed to an electron bath. As a result, higher negative charge states up to hexa-anionic clusters have been observed for the first time. In a parallel effort, di- and tri-anionic gold clusters have been produced in an RFQ-trap. To this end, an electron beam is guided through the RFQ-trap, which is operated by 2- or 3-state digital driving voltages. In addition, both polyanion-production techniques have been combined by pre-charging clusters in the RFQ-trap, transferring the resulting dianions into the Penning trap and applying the electron-bath technique to produce higher charge states.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2007-01-01

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

  5. Treatment of acute non-anion gap metabolic acidosis.

    Science.gov (United States)

    Kraut, Jeffrey A; Kurtz, Ira

    2015-02-01

    Acute non-anion gap metabolic acidosis, also termed hyperchloremic acidosis, is frequently detected in seriously ill patients. The most common mechanisms leading to this acid-base disorder include loss of large quantities of base secondary to diarrhea and administration of large quantities of chloride-containing solutions in the treatment of hypovolemia and various shock states. The resultant acidic milieu can cause cellular dysfunction and contribute to poor clinical outcomes. The associated change in the chloride concentration in the distal tubule lumen might also play a role in reducing the glomerular filtration rate. Administration of base is often recommended for the treatment of acute non-anion gap acidosis. Importantly, the blood pH and/or serum bicarbonate concentration to guide the initiation of treatment has not been established for this type of metabolic acidosis; and most clinicians use guidelines derived from studies of high anion gap metabolic acidosis. Therapeutic complications resulting from base administration such as volume overload, exacerbation of hypertension and reduction in ionized calcium are likely to be as common as with high anion gap metabolic acidosis. On the other hand, exacerbation of intracellular acidosis due to the excessive generation of carbon dioxide might be less frequent than in high anion gap metabolic acidosis because of better tissue perfusion and the ability to eliminate carbon dioxide. Further basic and clinical research is needed to facilitate development of evidence-based guidelines for therapy of this important and increasingly common acid-base disorder.

  6. Deflocculation of Cellulosic Suspensions with Anionic High Molecular Weight Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Markus Heikki Juhani Korhonen

    2014-04-01

    Full Text Available Pulp fibers have a strong tendency to form flocs in water suspensions, which may cause their undesirable distribution in the paper sheets. This flocculation can be controlled by adding, e.g., an anionic high molecular weight polyelectrolyte in the fiber suspension. The objective of this study was to investigate the effect of anionic polyelectrolytes on deflocculation kinetics, dewatering, and rheology of cellulosic suspensions. The results showed that both microfibrillated cellulose (MFC and macroscopic pulp fibers can be dispersed using anionic polyacrylamides (APAM. The higher the molecular weight of APAM, the higher is its effect. Adsorption experiments illustrate that anionic polyelectrolytes do not strongly attach to cellulose surfaces but they can be partly entrapped or can disperse nanocellulose fibrils (increase the swelling. Based on rheological experiments, the MFC network became weaker with APAM addition. Similar to the flocculation mechanism of cellulosic materials with polymers, deflocculation is also time dependent. Deflocculation occurs very rapidly, and the maximum deflocculation level is achieved within a few seconds. When mixing is continued, the floc size starts to increase again. Also dewatering was found to be strongly dependent on the contact time with the APAMs. These results indicate that the positive effects of anionic deflocculants are quickly diminished due to shear forces, and therefore, the best deflocculating effect is achieved using as short a contact time as possible.

  7. Vertical detachment energies of anionic thymidine: Microhydration effects

    Science.gov (United States)

    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)].

  8. Metal-Oxide Film Conversions Involving Large Anions

    Energy Technology Data Exchange (ETDEWEB)

    Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C. [The University of Western Ontario, Chemistry Department, 1151 Richmond St., N6A 5B7, London, Ontario (Canada)

    2008-07-01

    The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I{sup -}, Br{sup -}, S{sup 2-}). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag{sub 2}O to (1) AgI and (2) AgBr. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-01

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

  10. Determination of inorganic anions in papermaking waters by ion chromatography

    Directory of Open Access Journals (Sweden)

    DARJA ŽARKOVIĆ

    2009-03-01

    Full Text Available A suppressed ion chromatography (IC method for the determination of inorganic anions in process water from paperboard production was developed and validated. Common inorganic anions (Cl-, NO3-, PO43- and SO42- were detected in fresh and process water samples collected from a paperboard production system at 16 characteristic points. It was shown that the use of an IonPac®-AS14 column under isocratic conditions with Na2CO3/NaHCO3 as the eluent and a suppression device proved to be a reliable analytical solution for the separation of the inorganic anions present in papermaking waters. This IC method is quite satisfactory concerning selectivity and sensitivity, and enables the determination of several inorganic anions over a wide concentration range. According to the obtained results, the total amount of analyzed inorganic anions was below 0.1 g/L, i.e., below the critical value which may trigger operational problems in paper production.

  11. Solubility and transport of cationic and anionic patterned nanoparticles

    Science.gov (United States)

    Su, Jiaye; Guo, Hongxia; Olvera de La Cruz, Monica

    2012-02-01

    Diffusion and transport of nanoparticles (NPs) though nanochannels is important for desalination, drug delivery, and biomedicine. Their surface composition dictate their efficiency separating them by reverse osmosis, delivering into into cells, as well as their toxicity. We analyze bulk diffusion and transport through nanochannels of 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. The cationic NPs are more affected by the patterns, less water soluble, 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. For equivalent patterns, anionic NPs solubilize more than cationic NPs since the Coulomb interaction of free anionic NPs, which are much stronger than hydrophobic NP-water interactions, are about twice that of cationic NPs.

  12. Analysis of anions in geological brines using ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Merrill, R.M.

    1985-03-01

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

  13. Synthesis and anion binding properties of porphyrins and related compounds

    KAUST Repository

    Figueira, Flávio

    2016-12-02

    Over the last two decades the preparation of pyrrole-based receptors for anion recognition has attracted considerable attention. In this regard porphyrins, phthalocyanines and expanded porphyrins have been used as strong and selective receptors while the combination of those with different techniques and materials can boost their applicability in different applications as chemosensors and extracting systems. Improvements in the field, including the synthesis of this kind of compounds, can contribute to the development of efficient, cheap, and easy-to-prepare anion receptors. Extensive efforts have been made to improve the affinity and selectivity of these compounds and the continuous expansion of related research makes this chemistry even more promising. In this review, we summarize the most recent developments in anion binding studies while outlining the strategies that may be used to synthesize and functionalize these type of macrocycles. © 2016 World Scientific Publishing Company.

  14. Effect of anions on the electrochemistry of zinc tetraphenylporphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Seely, G.R.; Gust, D.; Moore, T.A.; Moore, A.L. (Arizona State Univ., Tempe, AZ (United States))

    1994-10-13

    Accurate measurements of porphyrin redox potentials are essential for the prediction and rationalization of the rates of electron transfer reactions involving these biologically important electron-donating and accepting chromophores. The present work describes a survey of redox potentials of zinc tetraphenylporphyrin obtained by cyclic voltammetry in dichloromethane, with tetrabutylammonium salts containing a variety of anions as electrolytes. Of the anions tested, hexafluorophosphate appears to have the least ability to ligate the metal, so that potentials measured in its presence as electrolyte should most closely approach those of the unligated porphyrin. With perchlorate electrolyte, the potential for one-electron oxidation is approximately 80 mV lower, enough to affect the interpretation of photochemical electron transfer rates. In general, anions bind much more strongly to the cation radical than to zinc tetraphenylporphyrin itself. The use of reference redox systems based on thymoquinone and ferrocene carboxylate enabled comparison of potentials measured with different electrolytes. 30 refs., 2 tabs.

  15. Cell wall bound anionic peroxidases from asparagus byproducts.

    Science.gov (United States)

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

    2014-10-08

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

  16. J774 macrophages secrete antibiotics via organic anion transporters.

    Science.gov (United States)

    Cao, C X; Silverstein, S C; Neu, H C; Steinberg, T H

    1992-02-01

    Mouse macrophages and J774 macrophage-like cells express probenecid-inhibitable organic anion transporters that remove anionic dyes from the cells' cytoplasmic matrix and secrete these dyes into the extracellular medium. The present studies show that these transporters also secrete antibiotics from J774 macrophages. Penicillin G permeates J774 cells poorly, but after it was introduced into the cell cytoplasm, it was secreted in a probenecid-inhibitable fashion. The quinolone norfloxacin enters macrophages readily. Probenecid retarded the secretion of intracellular norfloxacin by J774 cells and enhanced norfloxacin accumulation three- to fourfold. Thus the intracellular accumulation of norfloxacin is regulated in part by organic anion transporters that secrete norfloxacin (and penicillin G) from J774 cells. This transport process may have clinical significance, as fluoroquinolones inhibit growth of intracellular pathogens such as mycobacteria and Brucella organisms in vitro but fail to arrest infections with these organisms in vivo.

  17. Organization and function of anionic phospholipids in bacteria.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-15

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

  19. Surfactant behavior of "ellipsoidal" dicarbollide anions: a molecular dynamics study.

    Science.gov (United States)

    Chevrot, G; Schurhammer, R; Wipff, G

    2006-05-18

    We report a molecular dynamics study of cobalt bis(dicarbollide) anions [(B(9)C(2)H(8)X(3))(2)Co](-) (XCD(-)) commonly used in liquid-liquid extraction (X = H, Me, Cl, or Br), showing that these anions, although lacking the amphiphilic topology, behave as anionic surfactants. In pure water, they display "hydrophobic attractions", leading to the formation of aggregates of different sizes and shapes depending on the counterions. When simulated at a water/"oil" interface, the different anions (HCD(-), MeCD(-), CCD(-), and BrCD(-)) are found to be surface active. As a result, the simulated M(n+) counterions (M(n+) = Na(+), K(+), Cs(+), H(3)O(+), UO(2)(2+), Eu(3+)) concentrate on the aqueous side of the interface, forming a "double layer" whose characteristics are modulated by the hydrophobic character of the anion and by M(n+). The highly hydrophilic Eu(3+) or UO(2)(2+) cations that are generally "repelled" by aqueous interfaces are attracted by dicarbollides near the interface, which is crucial as far as the mechanism of assisted cation extraction to the oil phase is concerned. These cations interact with interfacial XCD(-) in their fully hydrated Eu(H(2)O)(9)(3+) and UO(2)(H(2)O)(5)(2+) forms, whereas the less hydrophilic monocharged cations display intimate contacts via their X substituents. The results obtained with the TIP3P and OPLS models for the solvents are confirmed with other water models (TIP5P or a polarizable 4P-Pol water) and with more polar "oil" models. The importance of interfacial phenomena is further demonstrated by simulations with a high oil-water ratio, leading to the formation of a micelle covered with CCD's. We suggest that the interfacial activity of dicarbollides and related hydrophobic anions is an important feature of synergism in liquid-liquid extraction of hard cations (e.g., for nuclear waste partitioning).

  20. Anionic fluoroquinolones as antibacterials against biofilm-producing Pseudomonas aeruginosa.

    Science.gov (United States)

    Long, Timothy E; Keding, Lexie C; Lewis, Demetria D; Anstead, Michael I; Withers, T Ryan; Yu, Hongwei D

    2016-02-15

    Pseudomonas aeruginosa is a common biofilm-forming bacterial pathogen implicated in diseases of the lungs. The extracellular polymeric substances (EPS) of respiratory Pseudomonas biofilms are largely comprised of anionic molecules such as rhamnolipids and alginate that promote a mucoid phenotype. In this Letter, we examine the ability of negatively-charged fluoroquinolones to transverse the EPS and inhibit the growth of mucoid P. aeruginosa. Anionic fluoroquinolones were further compared with standard antibiotics via a novel microdiffusion assay to evaluate drug penetration through pseudomonal alginate and respiratory mucus from a patient with cystic fibrosis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Corticosteroids increase superoxide anion production by rat liver microsomes.

    Science.gov (United States)

    Nelson, D H; Ruhmann-Wennhold, A

    1975-01-01

    Superoxide anion production by liver microsomes from intact, adrenalectomized, and cortisoltreated adrenalectomized rats has been determined. The amount formed was roughly proportionate to the amount of cortisol given, and a similar response was seen in the activity of NADPH-cytochrome c reductase. The amount of measurable superoxide anion was markedly reduced by the addition of superoxide dismutase. The increased production of this potent free radical with cortisol therapy suggests that its formation may contribute to some of the harmful effects of corticosteroids given in more than physiologic amounts. PMID:239969

  2. Electrostatic charge confinement using bulky tetraoctylammonium cation and four anions

    Science.gov (United States)

    Andreeva, Nadezhda A.; Chaban, Vitaly V.

    2016-04-01

    Thanks to large opposite electrostatic charges, cations and anions establish strong ionic bonds. However, applications of ionic systems - electrolytes, gas capture, solubilization, etc. - benefit from weaker non-covalent bonds. The common approaches are addition of cosolvents and delocalization of electron charge density via functionalization of ions. We report fine tuning of closest-approach distances, effective radii, and cation geometry by different anions using the semi-empirical molecular dynamics simulations. We found that long fatty acid chains employed in the tetraalkylammonium cation are largely inefficient and new substituents must be developed. The reported results foster progress of task-specific ionic liquids.

  3. Preparation of Cationic MOFs with Mobile Anions by Anion Stripping to Remove 2,4-D from Water

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2017-07-01

    Full Text Available A cationic porous framework with mobile anions (MIL-101(Cr-Cl was easily and successfully synthesized by utilizing the stronger affinity of F− to Al3+ than Cr3+ in the charge-balanced framework of MIL-101(Cr. The structure, morphology and porosity of MIL-101(Cr-Cl were characterized. The obtained new materials retain the high surface area, good thermostability, and structure topology of MIL-101(Cr. With the mobile Cl− anion, MIL-101(Cr-Cl can be used as an ion-exchange material for anionic organic pollutions. In this work, 2,4-dichlorophenoxyacetic acid (2,4-D was used as a model to test the absorption performance of this new material. This new material exhibited improved adsorbability compared to that of the original metal-organic frameworks (MOFs. At the same time, this material also shows high anti-interference performance with changing solution pH.

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

    CERN Document Server

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

    2004-01-01

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

  5. The anionic biosurfactant rhamnolipid does not denature industrial enzymes

    Directory of Open Access Journals (Sweden)

    Jens Kvist Madsen

    2015-04-01

    Full Text Available Biosurfactants (BS are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ, the phospholipase Lecitase Ultra® (LT and the α-amylase Stainzyme® (SZ. Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction towards the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the protein well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries to SZ. Furthermore all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant proteins. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.

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

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

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

  11. Anion effects on the cyclobis(paraquat-p-phenylene) host

    DEFF Research Database (Denmark)

    Andersen, Sissel Stenbæk; Jensen, Morten; Sørensen, Anne;

    2012-01-01

    Binding studies between the electron accepting host cyclobis(paraquat-p-phenylene) and a series of electron donors in the presence of differently sized counteranions reveal that both the nature and the concentration of the anion have a large impact on the association strength of the resulting host...

  12. Photocatalytic Anion Oxidation and Applications in Organic Synthesis.

    Science.gov (United States)

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

    2016-08-19

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

  13. Sheathless capillary electrophoresis-mass spectrometry for anionic metabolic profiling

    NARCIS (Netherlands)

    Gulersonmez, M.C.; Lock, S.; Hankemeier, T.; Ramautar, R.

    2016-01-01

    The performance of CE coupled on-line to MS via a sheathless porous tip sprayer was evaluated for anionic metabolic profiling. A representative metabolite mixture and biological samples were used for the evaluation of various analytical parameters, such as peak efficiency (plate numbers), migration

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

    Institute of Scientific and Technical Information of China (English)

    Li Xin ZHANG; Gui Zhi LI; Zhi Qiang LI

    2004-01-01

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

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

    DEFF Research Database (Denmark)

    Sørensen, Emil

    1973-01-01

    Test flotations have been carried out in a small apparatus under standardized conditions in order to determine the dependence of the flotation yield on the reagent concentration for certain minerals and anionic collectors. The results suggest that a special adsorption mechanism is operating...

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

    Science.gov (United States)

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

    2014-09-05

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

  17. Modelling the Effects of Competing Anions on Fluoride Removal by ...

    African Journals Online (AJOL)

    NICOLAAS

    Effects of each two anions exist simultaneously in aqueous solution on ... precipitation,6,7 membrane processes,8 electrochemical treat- ... is significantly dependent on the physico-chemical properties ... X-ray diffraction (XRD) measurements of the catalyst .... fluoride concentration (mg L–1) and X2 is the time of reaction.

  18. Spectral modulation through controlling anions in nanocaged phosphors

    NARCIS (Netherlands)

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

    2013-01-01

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

  19. Anion-exchange membranes in electrochemical energy systems

    NARCIS (Netherlands)

    Antanassov, Plamen B.; Dekel, Dario R.; Herring, Andrew M.; Hickner, Michael A.; Kohl, Paul A.; Kucernak, Anthony R.; Mustain, William E.; Nijmeijer, Kitty; Scott, Keith; Varcoe, John R.; Xu, Tongwen; Zhuang, Lin

    2014-01-01

    This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current stat

  20. Oxidation of silicon surface with atomic oxygen radical anions

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  1. Structures and energetics of hydrated oxygen anion clusters.

    Science.gov (United States)

    Chipman, Daniel M; Bentley, John

    2005-08-25

    Hydration of the atomic oxygen radical anion is studied with computational electronic structure methods, considering (O(-))(H(2)O)(n) clusters and related proton-transferred (OH(-))(OH)(H(2)O)(n)(-)(1) clusters having n = 1-5. A total of 67 distinct local-minimum structures having various interesting hydrogen bonding motifs are obtained and analyzed. On the basis of the most stable form of each type, (O(-))(H(2)O)(n)) clusters are energetically favored, although for n > or = 3, there is considerable overlap in energy between other members of the (O(-))(H(2)O)(n) family and various members of the (OH(-))(OH)(H(2)O)(n)(-)(1) family. In the lower-energy (O(-))(H(2)O)(n) clusters, the hydrogen bonding arrangement about the oxygen anion center tends to be planar, leaving the oxygen anion p-like orbital containing the unpaired electron uninvolved in hydrogen bonding with any water molecule. In (OH(-))(OH)(H(2)O)(n)(-)(1) clusters, on the other hand, nonplanar arrangements are the rule about the anionic oxygen center that accepts hydrogen bonds. No instances are found of OH(-) acting as a hydrogen bond donor. Those OH bonds that form hydrogen bonds to an anionic O(-) or OH(-) center are significantly stretched from their equilibrium value in isolated water or hydroxyl. A quantitative inverse correlation is established for all hydrogen bonds between the amount of the OH bond stretch and the distance to the other oxygen involved in the hydrogen bond.

  2. Synthesis of Novel Anionic Receptors with (Thio)urea and Amide Binding Sites and the Recognition Properties for Anions

    Institute of Scientific and Technical Information of China (English)

    吴进龙; 隗兰华; 曾振亚; 刘顺英; 龚睿; 孟令芝; 何永炳

    2003-01-01

    Two new neutral receptors (1 and 2) containing (thio)urea and amide groups were synthesized by simple steps in good yields.The binding properties for anions of 1 and 2 were characterized by UV-vis and fluorescence spectra. Receptor 1 had an excellent selectivity for AcO- in comparison with other anions. The association constants of 1·AcO- and 2·p-NO2PhOPO32- were higher than those of other anions (Cl-, Br-,I-, H2PO4- and p-NO2PhO-). In particular, an obvious color change was observed from light yellow to golden yellow upon addition of AcO- to the solution of 1 in DMSO. The results of non-linear curve fitting by UV-vis and fluorescence spectral data indicate that a 1:1 stoichiometry complex is formed between compound 1 or 2 and anions through a hydrogen bonding interaction.

  3. Anion Transport in a Chemically Stable, Sterically Bulky alpha-C Modified Imidazolium Functionalized Anion Exchange Membrane

    Science.gov (United States)

    2014-06-24

    comparison of benzyltrimethylammonium and 1-benzyl-3-methylimidazolium cationic groups with the same poly( ethylene -co-tetrafluoroethylene) (ETFE...12) Simone, P. M.; Lodge, T. P. Phase Behavior and Ionic Conductivity of Concentrated Solutions of Polystyrene-Poly( Ethylene Oxide) Diblock Copolymers...1514515144 Herring, A. M. Preparation and Characterization of an Alkaline Anion Exchange Membrane from Chlorinated Poly (Propylene) Aminated with

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

    Science.gov (United States)

    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.

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

    KAUST Repository

    Wallack, Maxwell J.

    2015-01-01

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

  6. Carbon dioxide suppresses macrophage superoxide anion production independent of extracellular pH and mitochondrial activity

    NARCIS (Netherlands)

    Kuebler, Joachim F.; Kos, Marcin; Jesch, NataLie K.; Metzelder, Martin L.; van der Zee, David C.; Bax, Klaas M.; Vieten, Gertrud; Ure, Benno M.

    2007-01-01

    Background: Superoxide anions released by activated inacrophages during surgery are considered to be responsible for local cellular damage. Application of CO2 prieumoperitoneum during laparoscopy affects superoxide anion release, but the underlying mechanism remains unclear and the data reported are

  7. 76 FR 2130 - Prospective Grant of Exclusive License: Inhibitors of the Plasmodial Surface Anion Channel as...

    Science.gov (United States)

    2011-01-12

    ... Plasmodial Surface Anion Channel as Antimalarials AGENCY: National Institutes of Health, Public Health... January 28, 2010, both applications entitled ``Inhibitors of the Plasmodial Surface Anion Channel As...: The subject technologies are antimalarial small molecule inhibitors of the plasmodial surface...

  8. A dual-emissive ionic liquid based on an anionic platinum(II) complex

    OpenAIRE

    Ogawa, Tomohiro; Yoshida, Masaki; Ohara, Hiroki; Kobayashia, Atsushi; Kato, Masako

    2015-01-01

    An ionic liquid fabricated froman anionic cyclometalated platinum(II) complex and an imidazolium cation exhibits dual emission from the monomeric and aggregated forms of the platinum complex anions, leading to temperature-dependent color changes of luminescence.

  9. A dual-emissive ionic liquid based on an anionic platinum(ii) complex.

    Science.gov (United States)

    Ogawa, Tomohiro; Yoshida, Masaki; Ohara, Hiroki; Kobayashi, Atsushi; Kato, Masako

    2015-09-07

    An ionic liquid fabricated from an anionic cyclometalated platinum(ii) complex and an imidazolium cation exhibits dual emission from the monomeric and aggregated forms of the platinum complex anions, leading to temperature-dependent color changes of luminescence.

  10. A Novel Benzimidazolyl based Receptor for the recognition of Fluoride and Cyanide Anion

    Indian Academy of Sciences (India)

    ERAMONI SAIKIA; PANKAJ DUTTA; BOLIN CHETIA

    2017-01-01

    A novel benzimidazole based ligand (1) has been synthesized and studied its anion recognition properties. The binding of anion with 1 was studied using UV-Visible spectroscopy, fluorescence spectroscopy and ¹H-NMR techniques at very low concentrations. The results obtained from the spectroscopic studies indicatethat ligand 1 is an efficient anion receptor providing changes in chemical shift and optical signals for the detection of two most environmentally important anions, fluoride and cyanide.

  11. Synthesis of an Anionic Receptor Based on Phenylhydrazone Group and Its Recognition Property for Acetate

    Institute of Scientific and Technical Information of China (English)

    WANG, Yue-Hong; LIN, Hai; LIN, Hua-Kuan

    2007-01-01

    A colorimetric anion receptor was synthesized by a simple method where the phenylhydrazone moiety was need as binding sites. The anion recognition via hydrogen-bonding interactions can be easily monitored by anion complexation induced changes in UV-vis absorption spectra. Moreover, the hydrogen bond formation between the phenylhydrazone N-H and acetate or fluoride anion was described on the basis of 1H NMR experiments.

  12. Formation and cleavage of aromatic disulfide radical anions.

    Science.gov (United States)

    Antonello, Sabrina; Daasbjerg, Kim; Jensen, Henrik; Taddei, Ferdinando; Maran, Flavio

    2003-12-03

    The electron transfer (ET) to a series of para-substituted diaryl disulfides, having the general formula (X-C(6)H(4)S-)(2), has been studied. The X groups were selected as to have a comprehensive variation of the substituent effect, being X = NH(2), MeO, H, F, Cl, CO(2)Et, CN, and NO(2). The reduction was carried out experimentally, using N,N-dimethylformamide as the solvent, and by molecular orbital (MO) ab initio calculations. The ET was studied heterogeneously, by voltammetric reduction and convolution analysis, and homogeneously, by using electrogenerated radical anions as the solution electron donors. The reduction is dissociative, leading to the cleavage of the S-S bond in a stepwise manner. Both experimental approaches led us to estimate the E degrees and the intrinsic barrier values for the formation of the radical anions. Comparison of the independently obtained results allowed obtaining, for the first time, a quantitative description of the correlation between heterogeneous and homogeneous rate constants of ETs associated with significant inner reorganization energy. The experimental outcome was fully supported by the theoretical calculations, which provided information about the disulfide lowest unoccupied MOs (LUMOs) and singly occupied MO (SOMO), the bond dissociation energies, and the most significant structural modifications associated with radical anion formation. With disulfides bearing electron-donating or mildly electron-withdrawing groups, the inner reorganization is particularly large, which reflects the significant stretching of the S-S bond experienced by the molecule upon ET. The process entails formation of loose radical anion species in which the SOMO is heavily localized, as the LUMO, onto the frangible bond. As a consequence of the formation of these sigma-radical anions, the S-S bond energy of the latter is rather small and the cleavage rate constant is very large. With electron-withdrawing groups, the extent of delocalization of the

  13. Contribution of various metabolites to the "unmeasured" anions in critically ill patients with metabolic acidosis.

    NARCIS (Netherlands)

    Moviat, M.; Terpstra, A.M.; Ruitenbeek, W.; Kluijtmans, L.A.J.; Pickkers, P.; Hoeven, J.G. van der

    2008-01-01

    OBJECTIVE: The physicochemical approach, described by Stewart to investigate the acid-base balance, includes the strong ion gap (SIG), a quantitative measure of "unmeasured" anions, which strongly correlates to the corrected anion gap. The chemical nature of these anions is for the most part

  14. Contact transfer of anions from hands as a function of the use of hand lotions

    Science.gov (United States)

    Welker, R. W.; Schulman, M.

    2001-01-01

    Contact transfer of anions from human hands can result in contamination of materials, increasing their rate of corrosion. Two types of hand lotion were applied to the hands: one was specially formulated for cleanroom use and the other was a popular commercial lotion. The effect on contact transfer of anions was measured versus anion transfer from washed hands without lotions.

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  17. Coumarin Based Neutral Sensor for Biologically Important Anions

    Institute of Scientific and Technical Information of China (English)

    SHAO Jie

    2011-01-01

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

  18. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    S Radha; P Vishnu Kamath

    2013-10-01

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

  19. Thermal Properties of Anionic Polyurethane Composition for Leather Finishing

    Directory of Open Access Journals (Sweden)

    Olga KOVTUNENKO

    2016-09-01

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

  20. Thermal Properties of Anionic Polyurethane Composition for Leather Finishing

    Directory of Open Access Journals (Sweden)

    Olga KOVTUNENKO

    2016-09-01

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

  1. Anionic reagents with silicon-containing double bonds.

    Science.gov (United States)

    Scheschkewitz, David

    2009-03-02

    E=Si transfer: Anionic compounds capable of transferring a silicon-containing double bond are reviewed (see figure), particularly reagents with Si=Si moieties (Tip=2,4,6-iPr(3)C(6)H(2), M=Li, Na, K) and their applications towards main-group and transition-metal electrophiles, as well as their reactivity towards organic compounds. A few recently reported derivatives with Si=C (Ad=1-adamantyl) and Si=P moieties are included for completeness.Anionic compounds capable of transferring a silicon double bond are summarized following an introduction to the differences between alkenes and their heavier homologues. The main focus is on reagents with Si=Si moieties and their applications towards main-group and transition-metal electrophiles, as well as their reactivity towards organic compounds, but a few recently reported derivatives with Si=C and Si=P bonds are also included.

  2. Molecular dynamics simulation of anionic clays containing glutamic acid

    Science.gov (United States)

    Xu, Qian; Ni, Zheming; Yao, Ping; Li, Yuan

    2010-08-01

    Supra-molecular structure of glutamic acid intercalated ZnAl layered double hydroxides (Glu-ZnAl-LDH) was modeled by molecular dynamics (MD) methods. Hydrogen bonding, hydration and swelling properties of Glu-LDH have been investigated. For Nw layers and anions. When A-W type H-bonds gradually reached a saturation state, water molecules continued to form hydrogen bonds with the hydroxyls of the layers. The L-W type H-bonds gradually substituted the L-A type H-bonds and Glu anions moved to the center of an interlayer and then separated with the layers. Last, a well-ordered structural water layer was formed on the surface hydroxyls of Glu-LDH. The lower releasing content of Glu-LDH maybe was influenced by the lower balance hydration energy and existence of L-A type H-bonds in high water content.

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

    Science.gov (United States)

    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.

  4. Continuous beds for microchromatography: chromatofocusing and anion exchange chromatography.

    Science.gov (United States)

    Li, Y M; Liao, J L; Zhang, R; Henriksson, H; Hjertén, S

    1999-02-01

    A method was developed for the preparation of continuous beds derivatized with polyethyleneimine (PEI) for chromatofocusing and anion exchange chromatography in the capillary mode. First, a continuous bed activated by epoxy groups was synthesized inside a fused silica capillary and became at the same time covalently attached to the inner wall of the capillary. A PEI solution was then pumped through the continuous bed to allow the imine groups in PEI to react with the epoxy groups in the bed. Efficient immobilization of PEI was indicated by the high-resolution separation of standard proteins (hemoglobins C, S, F, and A) in both chromatofocusing and anion exchange chromatography on a capillary column prepared by this method. Copyright 1999 Academic Press.

  5. Dihydrogen Phosphate Selective Anion Receptor Based on Acylhydrazone

    Energy Technology Data Exchange (ETDEWEB)

    Senthil Pandian, T.; Kang, Jongmin [Sejong Univ., Seoul (Korea, Republic of)

    2014-07-15

    Anion receptor based on acylhydrazone has been designed and synthesized. UV-vis and {sup 1}H NMR titration showed that receptor is selective receptor for dihydrogen phosphate (H{sub 2}PO{sub 4}{sup -}). Dihydrogen phosphate was complexed by the receptor via at least 4 hydrogen bonding interactions, contributing from two amide N-Hs and two imine C-Hs. In addition, nitrogen in the aromatic ring could make 2 additional hydrogen bondings with OH groups in the dihydrogen phosphate. However, the receptor could make only 4 hydrogen bonds with halides. Therefore, receptor could bind anions through hydrogen bonds with a selectivity in the order of H{sub 2}PO{sub 4}{sup -} > Br{sup -} > Cl{sup -} in highly polar solvent such as DMSO.

  6. Dendronized Anionic Gold Nanoparticles: Synthesis, Characterization, and Antiviral Activity.

    Science.gov (United States)

    Peña-González, Cornelia E; García-Broncano, Pilar; Ottaviani, M Francesca; Cangiotti, Michela; Fattori, Alberto; Hierro-Oliva, Margarita; González-Martín, M Luisa; Pérez-Serrano, Jorge; Gómez, Rafael; Muñoz-Fernández, M Ángeles; Sánchez-Nieves, Javier; de la Mata, F Javier

    2016-02-24

    Anionic carbosilane dendrons decorated with sulfonate functions and one thiol moiety at the focal point have been used to synthesize water-soluble gold nanoparticles (AuNPs) through the direct reaction of dendrons, gold precursor, and reducing agent in water, and also through a place-exchange reaction. These nanoparticles have been characterized by NMR spectroscopy, TEM, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, elemental analysis, and zeta-potential measurements. The interacting ability of the anionic sulfonate functions was investigated by EPR spectroscopy with copper(II) as a probe. Different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups for complexation by copper(II). Toxicity assays of AuNPs showed that those produced through direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV-1 infection was higher in the case of dendronized AuNPs than in dendrons.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-05

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

  8. Carbonate and Bicarbonate Ion Transport in Alkaline Anion Exchange Membranes

    Science.gov (United States)

    2013-06-25

    Bicarbonate Ion Transport in Alk Block 13: Supplementary Note © 2013 . Published in Journal of the Electrochemical Society , Vol. Ed. 0 160, (9) (2013...for public release; distribution is unlimited. ... 60325.7-CH-II F994 Journal of The Electrochemical Society , 160 (9) F994-F999 (2013) 0013-4651/2013...160(9)/F994/6/$31.00 © The Electrochemical Society Carbonate and Bicarbonate Ion Transport in Alkaline Anion Exchange Membranes Andrew M. Kiss,a

  9. Assessment Of Suitability Of Anionic Synthetic Detergents In Sri Lanka

    OpenAIRE

    Sunethra Gunatilake; Sarath Malavipathirana

    2015-01-01

    This research was focused on the understanding of the biodegradability of synthetic anionic detergent powder available in Sri Lankan market. Eight different types of synthetic detergent powders were selected. LAS contents of the selected products were measured according to ASTM D 3049-89 standard. The biodegradability was measured as the reduction percentage of LAS initially present within a specific period. The phosphate content in the detergents were measured by SLS 760 1986 method and the...

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

    Science.gov (United States)

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

    2014-09-01

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

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

    Science.gov (United States)

    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.

  12. Indirect photometric detection of boron cluster anions electrophoretically separated in methanol.

    Science.gov (United States)

    Vítová, Lada; Fojt, Lukáš; Vespalec, Radim

    2014-04-18

    3,5-Dinitrobenzoate and picrate are light absorbing anions pertinent to indirect photometric detection of boron cluster anions in buffered methanolic background electrolytes (BGEs). Tris(hydroxymethyl)aminomethane and morpholine have been used as buffering bases, which eliminated baseline steps, and minimized the baseline noise. In methanolic BGEs, mobilities of boron cluster anions depend on both ionic constituents of the BGE buffer. This dependence can be explained by ion pair interaction of detected anions with BGE cations, which are not bonded into ion pairs with the BGE anions. The former ion pair interaction decreases sensitivity of the indirect photometric detection.

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

    Institute of Scientific and Technical Information of China (English)

    Wan Yingxin; Liu Jianjun

    2007-01-01

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

  14. 2-Pyrrole Carboxylic Acid Nitro-Phenylamide: New Colorimetric Sensor for Anion

    Institute of Scientific and Technical Information of China (English)

    YIN Zhen-Ming; YANG Wen-Zhi; HE Jia-Qi; ZHU Xiao-Qing; CHENG Jin-Pei

    2003-01-01

    @@ Due to the role played by anions in the field of biology and environmental chemistry, the development of selec tive and sensitive chemosensor for anion sensing is a topic of current attention. Colorimetric anion sensor, which does not require the use of a potentiostate or spectrometer to detect redox or optical perturbation, can give immediate qualitative anion sensing information by visual detection and therefore has advantages over other molecular sensors.According the anion binding ability of some pyrrolic amides reported by Schmuck and Gale, we linked the color reporter group of nitroanile to pyrrole moiety and synthesized two 2-pyrrole carboxylic acid nitro-phenylamides (1 and 2).

  15. Ammoniated electron as a solvent stabilized multimer radical anion

    CERN Document Server

    Shkrob, I A

    2005-01-01

    The excess electron in liquid ammonia ("ammoniated electron") is commonly viewed as a cavity electron in which the s-type wave function fills the interstitial void between 6-9 ammonia molecules. Herewith an alternative model is examined in which the ammoniated electron is regarded as a solvent stabilized multimer radical anion, as was originally suggested by Symons [Chem. Soc. Rev. 1976, 5, 337]. In this model, most of the excess electron density resides in the frontier orbitals of N atoms in the ammonia molecules forming the solvation cavity; a fraction of this spin density is transferred to the molecules in the second solvation shell. The cavity is formed due to the repulsion between negatively charged solvent molecules. Using density functional theory calculations for small ammonia cluster anions in the gas phase, it is demonstrated that such core anions would quantitatively account for the observed pattern of Knight shifts for 1H and 14N nuclei as observed by NMR spectroscopy and the downshifted stretchin...

  16. Coumarin benzothiazole derivatives as chemosensors for cyanide anions.

    Science.gov (United States)

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

    2015-06-05

    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.

  17. Cassini observations of carbon-based anions in Titan's ionosphere

    Science.gov (United States)

    Desai, Ravindra; Lewis, Gethyn; Waite, J. Hunter; Kataria, Dhiren; Wellbrock, Anne; Jones, Geraint; Coates, Andrew

    2016-07-01

    Cassini observations of Titan's ionosphere revealed an atmosphere rich in positively and negatively charged ions and organic molecules. The detection of large quantities of negatively charged ions was particularly surprising and adds Titan to the growing list of locations where anion chemistry has been observed to play an important role. In this study we present updated analysis on these negatively charged ions through an enhanced understanding of the Cassini CAPS Electron Spectrometer (CAPS-ELS) instrument response. The ionisation of Titan's dominant atmospheric constituent, N2, by the HeII Solar line, results in an observable photoelectron population at 24.1eV which we use to correct for differential spacecraft charging. Correcting for further energy-angle signatures within this dataset, we use an updated fitting procedure to show how the ELS mass spectrum, previously grouped into broad mass ranges, can be resolved into specific peaks at multiples of carbon-based anion species up to over 100amu/q. These peaks are shown to be ubiquitous within Titan's upper atmosphere and reminiscent of carbon-based anions identified in dense molecular clouds beyond our Solar System. It is thus shown how the moon Titan in the Outer Solar System can be used as an analogue to study these even more remote and exotic astrophysical environments.

  18. Peroxidase activation of cytoglobin by anionic phospholipids: Mechanisms and consequences.

    Science.gov (United States)

    Tejero, Jesús; Kapralov, Alexandr A; Baumgartner, Matthew P; Sparacino-Watkins, Courtney E; Anthonymutu, Tamil S; Vlasova, Irina I; Camacho, Carlos J; Gladwin, Mark T; Bayir, Hülya; Kagan, Valerian E

    2016-05-01

    Cytoglobin (Cygb) is a hexa-coordinated hemoprotein with yet to be defined physiological functions. The iron coordination and spin state of the Cygb heme group are sensitive to oxidation of two cysteine residues (Cys38/Cys83) and/or the binding of free fatty acids. However, the roles of redox vs lipid regulators of Cygb's structural rearrangements in the context of the protein peroxidase competence are not known. Searching for physiologically relevant lipid regulators of Cygb, here we report that anionic phospholipids, particularly phosphatidylinositolphosphates, affect structural organization of the protein and modulate its iron state and peroxidase activity both conjointly and/or independently of cysteine oxidation. Thus, different anionic lipids can operate in cysteine-dependent and cysteine-independent ways as inducers of the peroxidase activity. We establish that Cygb's peroxidase activity can be utilized for the catalysis of peroxidation of anionic phospholipids (including phosphatidylinositolphosphates) yielding mono-oxygenated molecular species. Combined with the computational simulations we propose a bipartite lipid binding model that rationalizes the modes of interactions with phospholipids, the effects on structural re-arrangements and the peroxidase activity of the hemoprotein.

  19. Photostability enhancement of anionic natural dye by intercalation into hydrotalcite.

    Science.gov (United States)

    Kohno, Yoshiumi; Totsuka, Koichi; Ikoma, Shuji; Yoda, Keiko; Shibata, Masashi; Matsushima, Ryoka; Tomita, Yasumasa; Maeda, Yasuhisa; Kobayashi, Kenkichiro

    2009-09-01

    The aim of this study is the improvement of the photostability of several natural anionic dyes, carmine (CM), carthamus yellow (CY), and annatto dye (ANA), by complexation with hydrotalcite. The composite of the dyes and hydrotalcite is prepared by the coprecipitation method. CM is successfully intercalated in the hydrotalcite layer when the amount of introduced CM is large. The photostability of CM in CM/HT composites is superior to the CM adsorbed on silica surface. The effect of the stability enhancement is larger when the amount of introduced CM exceeds 0.23 g/g-host, or when the layer charge density of the hydrotalcite is larger. CY is also stabilized by complexation with hydrotalcite, whereas ANA is not stabilized by complexation with hydrotalcite. The photostability of an anionic natural dye can be improved by intercalation into the hydrotalcite layer, if the dye has a hydrophilic nature and a rather planar structure. The intercalated dye is stabilized by the protection from the attack of the atmospheric oxygen. In addition, contribution of the electrostatic interaction between the positively charged hydrotalcite layer and the intercalated anionic dye is also proposed.

  20. Anion composition of açaı́ extracts.

    Science.gov (United States)

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

    2013-06-26

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

  1. [Chromatographic separation of plasmid DNA by anion-exchange cryogel].

    Science.gov (United States)

    Guo, Yantao; Shen, Shaochuan; Yun, Junxian; Yao, Kejian

    2012-08-01

    Plasmid DNA (pDNA) is used as an important vector for gene therapy, and its wide application is restricted by the purity and yield. To obtain high-purity pDNA, a chromatographic method based on anion-exchange supermacroporous cryogel was explored. The anion-exchange cryogel was prepared by grafting diethylaminoethyl-dextran to the epoxide groups of polyacrylamide-based matrix and pUC19 plasmid was used as a target to test the method. The plasmid was transferred into Escherichia coli DH5alpha, cultivated, harvested and lysed. The obtained culture was centrifuged and the supernatant was used as the plasmid feedstock, which was loaded into the anion-exchange cryogel bed for chromatographic separation. By optimizing the pH of running buffer and the elution conditions, high-purity pDNA was obtained by elution with 0.5 mol/L sodium chloride solution at pH 6.6. Compared to the traditional methods for purification of pDNA, animal source enzymes and toxic reagents were not involved in the present separation process, ensuring the safety of both the purification operations and the obtained pDNA.

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

    Science.gov (United States)

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

    2016-08-01

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

  3. Coumarin benzothiazole derivatives as chemosensors for cyanide anions

    Science.gov (United States)

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

    2015-06-01

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

  4. Stability of atoms in the anionic domain (Z

    CERN Document Server

    Gil, G

    2013-01-01

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

  5. A Simple Halide-to-Anion Exchange Method for Heteroaromatic Salts and Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Neus Mesquida

    2012-04-01

    Full Text Available A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A− form in non-aqueous media. The anion loading of the AER (OH− form was examined using two different anion sources, acids or ammonium salts, and changing the polarity of the solvents. The AER (A− form method in organic solvents was then applied to several quaternary heteroaromatic salts and ILs, and the anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Relying on the hydrophobicity of the targeted ion pair for the counteranion swap, organic solvents with variable polarity were used, such as CH3OH, CH3CN and the dipolar nonhydroxylic solvent mixture CH3CN:CH2Cl2 (3:7 and the anion exchange was equally successful with both lipophilic cations and anions.

  6. Naked-eye detection of biologically important anions by a new chromogenic azo-azomethine sensor.

    Science.gov (United States)

    Rezaeian, Khatereh; Khanmohammadi, Hamid

    2014-12-10

    A new chromogenic azo-azomethine sensor, containing active phenolic sites, has been designed and synthesized via condensation reaction of N,N,N',N'-tetrakis(2-aminoethyl)-2,2-dimethyl propane-1,3-diamine with 1-(3-formyl-4-hydroxyphenylazo)-4-nitrobenzene. The anion recognition ability of the synthesized receptor was evaluated using UV-Vis spectroscopy and (1)H NMR technique. The anion recognition studies exhibited that the receptor acts as a sensor for biologically important anions such as F(-), AcO(-) and H2PO4(-) over other anions. The binding stoichiometry between sensor and anions was found to be 1:2. (1)H NMR experiment revealed that sensor recognizes anions via H-bonds and subsequent deprotonation to elicit a vivid color change. Interestingly, the sensory system not only let for the naked eye detection without any spectroscopic instrumentation but also helped to discriminate between anions.

  7. Repair effect of thymine radical anion by echinocoside using pulse radiolysis

    Institute of Scientific and Technical Information of China (English)

    李雯艳; 郑荣梁; 赵松岭; 姜岳; 林念芸

    1996-01-01

    Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.

  8. Anionic markers for the forensic identification of Chemical Ignition Molotov Cocktail composition.

    Science.gov (United States)

    Martín-Alberca, C; Ferrando, J L; García-Ruiz, C

    2013-03-01

    An improved version of the famous Molotov cocktail is the Chemical Ignition Molotov Cocktail (CIMC). This incendiary device contains chemical reagents that enable its self-ignition. The analysis of anions from CIMC residues by capillary electrophoresis (CE) allows the identification of the reagents used to produce the device, and provides forensic analysts with valuable information. Although, sulfate, chlorate, chloride, and perchlorate anions have been recently proposed in the literature as target anions to determine the CIMC composition, the identification of some of them could be controversial due to their presence in the environment. Therefore, the purpose of this study was to identify highly reliable anions capable of indicating the components used to prepare these self-initiated devices. The relationship among the detected anions in CIMC residues and the reagents employed in their elaboration is discussed. Some anions have been proposed as anionic markers of CIMC as incendiary devices. Additionally, the viability of different CIMC compositions was studied.

  9. Relative partial cross sections for anions formed upon electron attachment to nitrotoluene

    Science.gov (United States)

    Aleem, A.; Mauracher, A.; Sulzer, P.; Denifl, S.; Zappa, F.; Bacher, A.; Wendt, N.; Märk, T. D.; Scheier, P.

    2008-04-01

    Free electron attachment to the three different isomers of mono-nitrotoluene molecules in the gas phase is studied using a crossed electron-molecule beams technique. For the molecule 2-nitrotoluene 77 products anions are measured. The ion yield of the different anions spans a range of more than six orders of magnitude. The total anion yield of the three different isomers of mono-nitrotoluene is compared and shows remarkable differences mainly resulting from the different contributions of the NO2- fragment anions. The anion efficiency curves show six resonances that we assign to different transient negative ions. Competition of decay reactions is forming a series of fragment anions from each isomeric transient negative anion.

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

    Science.gov (United States)

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

    2016-03-01

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

  11. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    Science.gov (United States)

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-11-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl‑/SO42‑ separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl‑/SO42‑ permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

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

    Science.gov (United States)

    Khan, Asif Ali; Shaheen, Shakeeba

    2014-01-15

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

  13. A Newly Cloned ClC-3 Isoform, ClC-3d, as well as ClC-3a Mediates Cd2+-Sensitive Outwardly Rectifying Anion Currents

    Directory of Open Access Journals (Sweden)

    Toshiaki Okada

    2014-02-01

    Full Text Available Background: ClC-3, a member of the ClC family, is predicted to have six isoforms, ClC-3a to -3f, with distinct N- and C-terminal amino acid sequences. There have been conflicting reports on the properties of ClC-3a (also known as the N-terminal short form of ClC-3 and ClC-3b (the N-terminal long form of ClC-3 as plasmalemmal Cl- channels. Meanwhile, little is known about other isoforms. The amino acid sequence of ClC-3d (a C-terminal variant of the short form listed in the NCBI database was derived from the genomic sequence, but there has been no experimental evidence for the mRNA. Methods: PCR-cloning was made to obtain the full coding region of ClC-3d from mouse liver. Its molecular expression on the plasma membrane was microscopically examined in HEK293T cells transfected with GFP-tagged ClC-3d. Its functional plasmalemmal expression and the properties of currents were studies by whole-cell recordings in the cells transfected with ClC-3d. Results: The cloned ClC-3d was found to be the only isoform which has an N-terminal amino acid sequence identical to ClC-3a. When introduced into HEK293T cells, a minor fraction of exogenous ClC-3d proteins was detected at the plasma membrane, and activation of anion currents was observed at neutral pH under normotonic conditions. The properties of ClC-3d currents were found to be shared by ClC-3a-mediated currents. Also, both ClC-3d and -3a currents were found to be sensitive to Cd2+. ClC-3d overexpression never affected the endogenous activity of acid- or swelling-activated anion channels. Conclusion: We thus conclude that plasmalemmal ClC-3d, like ClC-3a, mediates Cd2+-sensitive outwardly rectifying anion currents and that ClC-3d is distinct from the molecular entities of acid- and volume-sensitive anion channels.

  14. Predicting the Strength of Anion-π Interactions of Substituted Benzenes: the Development of Anion-π Binding Substituent Constants.

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Nakatani, Nobutake; Kozaki, Daisuke; Tanaka, Kazuhiko

    2012-04-01

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

  17. Lysozyme stability and amyloid fibrillization dependence on Hofmeister anions in acidic pH.

    Science.gov (United States)

    Poniková, Slavomíra; Antošová, Andrea; Demjén, Erna; Sedláková, Dagmar; Marek, Jozef; Varhač, Rastislav; Gažová, Zuzana; Sedlák, Erik

    2015-09-01

    We have explored an effect of Hofmeister anions, Na2SO4, NaCl, NaBr, NaNO3, NaSCN and NaClO4, on stability and amyloid fibrillization of hen egg white lysozyme at pH 2.7. The stability of the protein was analyzed by differential scanning calorimetry. The Hofmeister effect of the anions was assessed by the parameter dT trs/d[anion] (T trs, transition temperature). We show that dT trs/d[anion] correlates with anion surface tension effects and anion partition coefficients indicating direct interactions between anions and lysozyme. The kinetic of amyloid fibrillization of lysozyme was followed by Thioflavin T (ThT) fluorescence. Negative correlation between dT trs/d[anion] and the nucleation rate of fibrillization in the presence of monovalent anions indicates specific effect of anions on fibrillization rate of lysozyme. The efficiency of monovalent anions to accelerate fibrillization correlates with inverse Hofmeister series. The far-UV circular dichroism spectroscopy and atomic force microscopy findings show that conformational properties of fibrils depend on fibrillization rate. In the presence of sodium chloride, lysozyme forms typical fibrils with elongated structure and with the secondary structure of the β-sheet. On the other hand, in the presence of both chaotropic perchlorate and kosmotropic sulfate anions, the fibrils form clusters with secondary structure of β-turn. Moreover, the acceleration of fibril formation is accompanied by decreased amount of the formed fibrils as indicated by ThT fluorescence. Taken together, our study shows Hofmeister effect of monovalent anions on: (1) lysozyme stability; (2) ability to accelerate nucleation phase of lysozyme fibrillization; (3) amount, and (4) conformational properties of the formed fibrils.

  18. Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport

    Science.gov (United States)

    Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.

    2002-12-01

    The physical, chemical, and biological controls on contaminant mobilities in aquatic ecosystems must be determined to establish the threat that contamination poses to the environment. Quantitative models of contaminant mobilities are required as a prerequisite to guide remediation efforts and to prioritize the potential hazard to the ecosystem of each contaminated site. It is well established that mineral surface adsorption is an important control on contaminant mobilities, and many studies have utilized thermodynamics to quantify metal/organic adsorption in order to yield predictive models of contaminant transport. However, these models of contaminant transport may not be representative of the reactions which control contaminant mobilities as most mineral surfaces are coated with organic acids, bacteria, and extracellular polymers. Numerous laboratory studies have demonstrated that bacterial cell walls have a high affinity for binding metal cations, and field studies indicate that a significant proportion of bacteria cells and associated extracellular matrices are coated with small scale hydrous metal oxides. The small size of bacteria, and in many cases the nanoscale of their associated mineral phases, suggests these bacteria-mineral composites may represent a large proportion of surface area exposed to fluid flow. Therefore, due to the affinity of bacterial cell walls for cations and biominerals, bacteria may also have a significant impact on anionic contaminant mobility in many natural systems. The extent of metal-bacteria adsorption reactions varies drastically as a function of pH and solution chemistry. Current adsorption models have focused on the interactions of positively charged metal cations with bacterial surfaces, however in many oxidizing environments metals such as Cr exist as anions or anionic complexes. We have studied the ability of non-metabolizing cells of the bacterial species Bacillus subtilis and Shewanella putrifaciens to adsorb aqueous Cr

  19. Chemistry of nitrile anions in the interstellar medium

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-31

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

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

    KAUST Repository

    Oburger, E.

    2011-07-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-07-01

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

  2. Minority anion substitution by Ni in ZnO

    CERN Document Server

    Pereira, Lino Miguel da Costa; Correia, João Guilherme; Amorim, Lígia Marina; Silva, Daniel José; David-Bosne, Eric; Decoster, Stefan; da Silva, Manuel Ribeiro; Temst, Kristiaan; Vantomme, André

    2013-01-01

    We report on the lattice location of implanted Ni in ZnO using the $\\beta$− emission channeling technique. In addition to the majority substituting for the cation (Zn), a significant fraction of the Ni atoms occupy anion (O) sites. Since Ni is chemically more similar to Zn than it is to O, the observed O substitution is rather puzzling. We discuss these findings with respect to the general understanding of lattice location of dopants in compound semiconductors. In particular, we discuss potential implications on the magnetic behavior of transition metal doped dilute magnetic semiconductors.

  3. Methylglyoxal as a scavenger for superoxide anion-radical.

    Science.gov (United States)

    Shumaev, K B; Lankin, V Z; Konovalova, G G; Grechnikova, M A; Tikhaze, A K

    2016-07-01

    Methylglyoxal at a concentration of 5 mM caused a significant inhibition of superoxide anion radical (O2 (·-)) comparable to the effect of Tirone. In the process of O2 (·-) generation in the system of egg phosphatidylcholine liposome peroxidation induced by the azo-initiator AIBN, a marked inhibition of chemiluminescence in the presence of 100 mM methylglyoxal was found. At the same time, methylglyoxal did not inhibit free radical peroxidation of low-density lipoprotein particles, which indicates the absence of interaction with methylglyoxal alkoxyl and peroxyl polyenoic lipid radicals. These findings deepen information about the role of methylglyoxal in the regulation of free radical processes.

  4. Transmembrane anion transport and cytotoxicity of synthetic tambjamine analogs.

    Science.gov (United States)

    Hernando, Elsa; Soto-Cerrato, Vanessa; Cortés-Arroyo, Susana; Pérez-Tomás, Ricardo; Quesada, Roberto

    2014-03-21

    Ten synthetic analogs of the marine alkaloids tambjamines, bearing aromatic enamine moieties, have been synthesized. These compounds proved to be highly efficient transmembrane anion transporters in model liposomes. Changes in the electronic nature of the substituents of the aromatic enamine or the alkoxy group of the central pyrrole group did not affect this anionophore activity. The in vitro activity of these compounds has also been studied. They trigger apoptosis in several cancer cell lines with IC50 values in the low micromolar range as well as modify the intracellular pH, inducing the basification of acidic organelles.

  5. Modeling Donnan Dialysis Separation for Carboxylic Anion Recovery

    DEFF Research Database (Denmark)

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

    2010-01-01

    dynamic model for transport of multiple ions through an anion exchange membrane is derived based on an irreversible thermodynamics approach. This model accounts for the convective transport of the dissociated and undissociated species in the channels with diffusion and migration across the boundary...... layers and membranes. Donnan equilibrium, flux continuity of the transported ions, the electroneutrality condition and Faraday's law are employed to describe the electrical potential and concentration discontinuities at the interfaces. The Nernst-Planck equation is used to model the ion transport though...

  6. Predicting Carbonate Ion Transport in Alkaline Anion Exchange Materials

    Science.gov (United States)

    2012-01-01

    Electrochemical Society , 2013. 2. Wilson K. S. Chiu, "Part 1. Role of the 3-D Electrode Microstructure on Charge Transfer, Mass Transfer, and Electrochemical Reactions in Solid Oxide Fuel Cells; Part 2. Ion and Water Transport in Alkaline Anion Exchange Membranes," technical seminar for the Army Research Laboratory (host: Dr. Deryn Chu), Adelphi, MD, August 13, 2012. (c) Presentations Number of Presentations: 2.00 Non Peer-Reviewed Conference Proceeding publications (other than abstracts): Received Paper TOTAL: Number of Non Peer-Reviewed

  7. On the real structure of profiled anion-deficient corundum

    Science.gov (United States)

    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.

  8. Anion and Cation Ionic Conductivity of Dragon Fruit

    Science.gov (United States)

    Hajar, Nadya; Asiah, M. N.; Abdullah, S.; Rusop, M.

    2010-07-01

    The separation of all ions in a synthetic solution was achieved with an anion eluent containing 0.3392 g Na2CO3 and 0.084 g NaHCO2 and the run around 20 min. Cation eluent containing 0.60 g Tartaric acid and 0.125 g Dipicolinic acid and the run around 16 min. This method was applied to dragon fruit juice with success and has shown sensitivity. Moreover, sample preparation was a simple 1:1, 1:10, 1:100 and 1:1000 ppm with 0.20 mm filtration and direct injection without prior sample clean-up. Due to the use of eluent generator, very low conductance background conductivity can be obtained and sensitivity of dragon fruit has been greatly improved. Under the experimental condition, several inorganic anions, such as F-, NO3-, NO2-, Br- and PO43- obtained from dragon fruit. For cation, inorganic ions that occurred during the experiment were NH3+, Ca+, and Mg+. Conductivity for anion of F-, NO3-, NO2-, Br- and PO43- were approximately 20, 17, 16, 16 and 20 μS/cm, respectively. Concentration for F- is 1.57 mg/l, NO3- is 1.92 mg/l, NO2- is 0.30 mg/l, Br- is 0.45 mg/l and PO43- is 4.45 mg/l. Conductivity for cation of NH3+, Ca+, and Mg+ were approximately 537, 538 and 531 μS/cm, respectively. Concentration for cation of NH3+ is 0.93 mg/l, Ca+ is 1.15 mg/l, and Mg+ 7.285 is mg/l. The method has successfully applied to the determination of inorganic ions in dragon fruit. An ion chromatography method is described for the simultaneous determination of ionic conductivity for dragon fruit juice using a selected anion and cation eluent. The detection of ionic conductivity in dragon fruit juice has been studied.

  9. Enhanced Anion Transport Using Some Expanded Porphyrins as Carriers.

    Science.gov (United States)

    1991-01-01

    step, an acid catalyzed 1: 1 Schiff - base condensation between I ,8-diaminoanthracene 4 and 2,5-bis((3-ethylS_-formyl-4- methy’lpyrrol-2-yl) methyl... Schiff base "expanded porphyrin," 1, which when diprotonated effectively binds chloride anion in the solid state.8- 10 In addition, we present the results...parent, 1, is shown in Scheme 1. It involves, as the critical step, the acid catalyzed 1:1 Schiff - base condensation between 1.8-diaminoanthracene 49

  10. CONTROLLED ANIONIC SYNTHESIS OF FUNCTIONALIZED AND STAR-BRANCHED POLYMERS

    Institute of Scientific and Technical Information of China (English)

    RODERIC P. QUIRK; YIN Jian; GUO Shaohua; HU Xiaowei; GABRIEL SUMMERS; KIM Jungahn; ZHU Linfang; LAUREL E. SCHOCK

    1990-01-01

    The use of living, alkyllithium-initiated anionic polymerization to prepare chain-end functionalized polymers and heteroarm, star- branched polymers is discussed. The scope and limitations of specific termination reactions with a variety of electrophilic species are illustrated for carbonation, hydroxyethylation,amination, and sulfonation. The methodology of using substituted 1,1- diphenylethylenes to provide a general, quantitative functionalization procedure is outlined and illustrated with examples of amine and phenol end-functionalization. A methodology is described for the synthesis of functionalized,star-branched copolymers with compositionally heterogeneous arms of controlled molecular weight and narrow molecular weight distribution using 1, 3-bis (1-phenylethenyl) benzene.

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

  12. A bambusuril macrocycle that binds anions in water with high affinity and selectivity.

    Science.gov (United States)

    Yawer, Mirza Arfan; Havel, Vaclav; Sindelar, Vladimir

    2015-01-02

    Synthetic receptors that function in water are important for the qualitative and quantitative detection of anions, which may act as pollutants in the environment or play important roles in biological processes. Neutral receptors are particularly appealing because they are often more selective than positively charged receptors; however, their affinity towards anions in pure water is only in range of 1-10(3)  L mol(-1) . The anion-templated synthesis of a water-soluble bambusuril derivative is shown to be an outstanding receptor for various inorganic anions in pure water, with association constants of up to 10(7)  L mol(-1) . Furthermore, the macrocycle discriminates between anions with unprecedented selectivity (up to 500 000-fold). We anticipate that the combination of remarkable affinity and selectivity of this macrocycle will enable the efficient detection and isolation of diverse anions in aqueous solutions, which is not possible with current supramolecular systems.

  13. Acylthiourea derivatives as colorimetric sensors for anions: Synthesis, characterization and spectral behaviors.

    Science.gov (United States)

    Liu, Shuangshuang; Kang, Jing; Cao, Xiufang; Yue, Xiali

    2016-01-15

    Several acylthioureas have been synthesized to develop colorimetric sensors for detection of biologically important anions. UV-vis titration experiments indicated that the absorbance values have a good linear relationship with concentration of anions when the anions were added in AR-1, AR-4 and AR-6 sensor molecules. The detection limit to AcO(-) and F(-) is 5×10(-6) mol/L when the concentration of receptors are 2×10(-5) mol/L. Especially, compounds AR-1 and AR-4, decorated with strong electron-withdrawing NO2 substituent, showed augmented anion sensing properties, being capable of naked-eye detecting of F(-) and AcO(-) when the water content is lower than 15%. The recognition details of anion sensing were also assessed using (1)H NMR technique and confirmed that the basic anions induced deprotonation of N-H.

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

    Directory of Open Access Journals (Sweden)

    S. Gago

    2004-12-01

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

  15. Molecular Dynamics Investigation of Efficient SO₂ Absorption by Anion-Functionalized Ionic Liquids

    Indian Academy of Sciences (India)

    ANIRBAN MONDAL; SUNDARAM BALASUBRAMANIAN

    2017-07-01

    Ionic liquids are appropriate candidates for the absorption of acid gases such as SO₂. Six anion functionalized ionic liquids with different basicities have been studied for SO₂ absorption capacity by employing quantum chemical calculations and molecular dynamics (MD) simulations. Gas phase quantum calculations unveil that the high uptake of SO₂ in these ionic liquids originates from the basicity of the anions and the consequent enhanced anion-SO₂ interactions. MD simulations of SO₂–IL mixtures reveal the crucial role of both cations and anions in SO₂ dissolution. Multiple-site interactions of SO₂ with the anions have been identified. The calculated solvation free energy substantiates these observations. The order of computed Henry’s law constant values with change in the anion is in fair agreement with experimentally determined SO₂ solubility order.

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

    Science.gov (United States)

    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.

  17. Effects of sodium molybdate on osmolytes and membrane stability of Pennisetum alopecuroides seedlings under low temperature stress%钼酸钠对低温胁迫下狼尾草渗透调节物质和膜稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    张翠平; 王艳慧; 袁小环; 邢晓云; 彭向永

    2012-01-01

    以狼尾草(Pennisetum alopecuroides)为材料,研究了不同质量浓度的钼酸钠对低温胁迫下狼尾草幼苗中几种渗透调节物质含量和细胞膜稳定性的影响。结果表明,钼酸钠可显著提高低温胁迫下的狼尾草叶片总叶绿素、可溶性蛋白质、抗坏血酸、可溶性糖、游离脯氨酸等物质的含量,降低丙二醛含量和细胞膜透性,缓解狼尾草受到的低温冷害;钼酸钠缓解低温胁迫的最低效应质量浓度为0.5mg.L-1,且在0.5~5.0mg.L-1质量浓度范围内对狼尾草渗透调节物质和细胞膜稳定性的影响无显著差异。%Effects of different concentrations of sodium molybdate on osmolytes and membrane stability of Pennisetum alopecuroides seedlings under low temperature stress were investigated in this study. Results of experiments indicated that sodium molybdate application in P. alopecuroides seedlings induced a dramat- ic increase in total chlorophyll, soluble protein, ascorbic acid, soluble sugar and free proline contents under low temperature stress. Sodium molybdate application also caused a significant decrease in malondi- aldehyde content and membrane permeability. The lowest effect concentration of sodium molybdate appli- cation was 0. 5 mg ·L-1 to alleviate the low temperature stress. There was no significant difference in osmolytes and membrane stability of P. alopecuroides seedlings treated with sodium molybdate at the 0.5-5.0 mg·L-1 concentration range. It could be speculated that sodium molybdate application enhanced cold resistance by increasing the osmolyte content and alleviating membrane damage in P. alopecuroides seedlings under low temperature stress.

  18. Liquid anion-exchange separation of vanadium from malonate media

    Energy Technology Data Exchange (ETDEWEB)

    Rao, R.R.; Khopkar, S.M. (Indian Inst. of Technology, Dept. of Chemistry, Bombay (India))

    1992-06-01

    Vanadium (IV) and (V) can be quantitatively extracted with 0.2 mol/l Amberlite LA-2 in xylene at pH 3.0 from 0.02 mol/l malonic acid, stripped with 0.5 mol/l hydrochloric acid, and determined spectrophotometrically. Five other liquid anion exchangers (Amberlite LA-1, Primene JM-T, Aliquat 336S, TOA and TIOA) were examined as possible extractants. The extraction of vanadium(IV) was found to be quantitative only with Amberlite LA-2, while that of vanadium(V) was quantitative with Amberlite LA-1 and LA-2, Primene JM-T and Aliquat 336S. Eight common solvents were tested as diluents; of these hexane, cyclohexane, benzene, and xylene were found to be satisfactory. Vanadium was separated from elements that do not form anionic complexes with malonic acid by selective extraction, from those that form weak complexes by washing the organic extract with water, and from metals that form strong malonato complexes by selective stripping with hydrochloric, nitric, or sulphuric acid. The method has been applied to the determination of vanadium in steel, coal fly ash and fuel oil. The precision of measurement is within {+-}5% and the detection limit of the method for vanadium is 0.5 mg/kg. (orig.).

  19. Functional role of anion channels in cardiac diseases

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  20. Implosive Interatomic Coulombic decay in the simplest molecular anion

    Science.gov (United States)

    Greene, Chris H.; Perez-Rios, Jesus; Slipchenko, Lyudmila

    2016-05-01

    Interatomic Coulombic decay (ICD) has been extensively studied in different systems: from diatomic systems such as He2 up to more complex chemical systems with interest in biochemistry. Independently of the size and complexity of the system, the ICD process proposed involves the emission of an electron through exchange of a virtual photon. The present theoretical study investigates the ICD process in the helium hydride anion, which involves two final product states that can be produced through a Coulomb implosion following high energy ejection of a He 1s electron accompanied by excitation to He+(n = 2) . One of the subsequent decay channels is associated with the usual emission of a single electron, to produce a stable molecule: HeH+, which can compete with the usual dissociated final state of the system. The second channel involves the emission of two electrons, leading to the usual Coulomb explosion of the final product ions He+(1 s) + H + . In addition, the process of formation of the helium hydride anion is analyzed in terms of the existing technology of ionic molecular beams and buffer gas cooling techniques. This work is supported by the National Science Foundation under Grant PHY-1306905.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-08

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

  2. Synthetic cation-selective nanotube: Permeant cations chaperoned by anions

    Science.gov (United States)

    Hilder, Tamsyn A.; Gordon, Dan; Chung, Shin-Ho

    2011-01-01

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  3. Destabilization of Surfactant-Dispersed Carbon Nanotubes by Anions

    Science.gov (United States)

    Hirano, Atsushi; Gao, Weilu; He, Xiaowei; Kono, Junichiro

    2017-01-01

    The colloidal stability of surfactant-dispersed single-wall carbon nanotubes (SWCNTs) is determined by microscopic physicochemical processes, such as association, partitioning, and adsorption propensities. These processes can be controlled by the addition of solutes. While the effects of cations on the colloidal stability of SWCNTs are relatively well understood, little is known about the effects of anions. In this study, we examined the effects of anions on the stability of SWCNTs dispersed by sodium dodecyl sulfate (SDS) using sodium salts, such as NaCl and NaSCN. We observed that the intensity of the radial breathing mode Raman peaks rapidly decreased as the salts were added, even at concentrations less than 25 mM, indicating the association of SWCNTs. The effect was stronger with NaSCN than NaCl. We propose that the association of SWCNTs was caused by thermodynamic destabilization of SDS assemblies on SWCNT surfaces by these salts, which was confirmed through SWCNT separation experiments using aqueous two-phase extraction and gel chromatography. These results demonstrate that neutral salts can be used to control the colloidal stability of surfactant-dispersed SWCNTs.

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

    Directory of Open Access Journals (Sweden)

    Todorović Žaklina N.

    2016-01-01

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

  5. Amination of energetic anions: high-performing energetic materials.

    Science.gov (United States)

    Klapötke, Thomas M; Piercey, Davin G; Stierstorfer, Jörg

    2012-08-21

    The new energetic materials 2-amino-5-nitrotetrazole (ANT, 1), 1-amino-3,4-dinitro-1,2,4-triazole (ADNT, 2), and both 1,1'-diamino-5,5'-bistetrazole and 1,2'-diamino-5,5'-bistetrazole (11DABT, 3 and 12DABT, 4) have been prepared by the amination of the parent anion with O-tosylhydroxylamine. The 5-H-tetrazolate anion has also been aminated using hydroxylamine O-sulfonic acid to both 1-aminotetrazole and 2-aminotetrazole (1AT, 5 and 2AT, 6). The prepared materials have been characterized chemically (XRD (1-4, 6·AtNO(2), 8), multinuclear NMR, IR, Raman) and as explosives (mechanical and electrostatic sensitivity) and their explosive performances calculated using the EXPLO5 computer code. The prepared N-amino energetic materials, which can also be used as new ligands for high energy-capacity transition metal complexes, exhibit high explosive performances (in the range of hexogen and octogen) and a range of sensitivities from low to extremely high.

  6. Dynamics of anion-molecule reactions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikosch, J.

    2007-11-15

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

  7. Octulene: A Hyperbolic Molecular Belt that Binds Chloride Anions.

    Science.gov (United States)

    Majewski, Marcin A; Hong, Yongseok; Lis, Tadeusz; Gregoliński, Janusz; Chmielewski, Piotr J; Cybińska, Joanna; Kim, Dongho; Stępień, Marcin

    2016-11-02

    Octulene, the higher homologue of kekulene and septulene, was synthesized using the fold-in method. This new hydrocarbon macrocycle contains a large 24-membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion of the π-conjugated surface. The consequences of distortion in octulene were explored using photophysical methods, which revealed a reduced electronic band gap and greater flexibility of the π system. Octulene contains a functional cavity with a diameter larger than 5.5 Å that is capable of efficiently binding the chloride anion in a nonpolar solvent (Ka = 2.2(4)×10(4)  m(-1) , 1 % dichloromethane (DCM) in benzene). The octulene-chloride interaction is stabilized by eight weak C(sp(2) )H⋅⋅⋅Cl bonds, providing the first example of a hydrocarbon-based anion receptor. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. A nitro radical anion formation from nifedipine: an electrochemical approach.

    Science.gov (United States)

    Squella, J A; Solabarrieta, C; Nuñez-Vergara, L J

    1993-12-01

    The cyclic voltammetric behaviour of nifedipine was studied. The addition of three aprotic solvents to nifedipine in an aqueous citrate buffer system was examined. Qualitatively they result in separation of the initial irreversible 4 electron reduction into two stages, the NO2/RNO2.- and RNO2.-, 4H/RNHOH, H2O couples, respectively. Particular attention was directed to the 1-electron RNO2/RNO2.- couple as measured by the cyclic voltammetric mode in mixed media. Analysis of the cyclic voltammetric response as a function of scan rate and non-aqueous solvent content yields information on the stability of the radical anion. The chemical forward reaction of the radical anion follows a second order kinetics with a stability constant of 1.1 x 10(-3) l mol-1 s-1 and a half-life time of 0.09 s for 1 mM of nifedipine in aqueous citrate buffer, pH 7.4/DMF; 50:50.

  9. Assessment Of Suitability Of Anionic Synthetic Detergents In Sri Lanka

    Directory of Open Access Journals (Sweden)

    Sunethra Gunatilake

    2015-08-01

    Full Text Available This research was focused on the understanding of the biodegradability of synthetic anionic detergent powder available in Sri Lankan market. Eight different types of synthetic detergent powders were selected. LAS contents of the selected products were measured according to ASTM D 3049-89 standard. The biodegradability was measured as the reduction percentage of LAS initially present within a specific period. The phosphate content in the detergents were measured by SLS 760 1986 method and the pH of the media also was obtained to find any relationship between these parameters. The results found that the biodegradability of LAS in detergent powder is ranged between 24-79. This study found that the biodegradability of anionic surfactants highly depend on the phosphate content of the product. According to SLS 7601986 minimum LAS which has to be maintained in the Sri Lankan synthetic detergent and the existing legislations for the manufacturing marketing and consuming of detergent products should have modified for the health and safety environment. Therefore further studies need to be conducted to determine the maximum allowable level of phosphates lead to the highest level of biodegradability.

  10. Anionic and cationic Hofmeister effects on hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Schwierz, Nadine; Horinek, Dominik; Netz, Roland R

    2013-02-26

    Using a two-step modeling approach, we address the full spectrum of direct, reversed, and altered ionic sequences as the charge of the ion, the charge of the surface, and the surface polarity are varied. From solvent-explicit molecular dynamics simulations, we extract single-ion surface interaction potentials for halide and alkali ions at hydrophilic and hydrophobic surfaces. These are used within Poisson-Boltzmann theory to calculate ion density and electrostatic potential distributions at mixed polar/unpolar surfaces for varying surface charge. The resulting interfacial tension increments agree quantitatively with experimental data and capture the Hofmeister series, especially the anomaly of lithium, which is difficult to obtain using continuum theory. Phase diagrams that feature different Hofmeister series as a function of surface charge, salt concentration, and surface polarity are constructed from the long-range force between two surfaces interacting across electrolyte solutions. Large anions such as iodide have a high hydrophobic surface affinity and increase the effective charge magnitude on negatively charged unpolar surfaces. Large cations such as cesium also have a large hydrophobic surface affinity and thereby compensate an external negative charge surface charge most efficiently, which explains the well-known asymmetry between cations and anions. On the hydrophilic surface, the size-dependence of the ion surface affinity is reversed, explaining the Hofmeister series reversal when comparing hydrophobic with hydrophilic surfaces.

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

    Institute of Scientific and Technical Information of China (English)

    XU Xianzhu; SONG Jiangwei; LI Defeng; XIAO Fengshou

    2004-01-01

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

  12. Tungstate and Carbonate Ions Sorption Using Anion Exchangers AV-17-8 and Purolite A400

    Directory of Open Access Journals (Sweden)

    Chegrintsev S.

    2016-01-01

    Full Text Available The current paper shows the results of tungstate and carbonate ion sorption using strongly basic anion exchangers AV-17-8 and Purolite A400. It has been established that anion exchanger AV-17-8 in the chloride form with parameters of 168 g of tungstate ion and 157 g of carbonate ion per 1 kg of anion exchanger has the maximum capacity for the tungstate and carbonate ions.

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

    Institute of Scientific and Technical Information of China (English)

    A. Y. Galashev

    2015-01-01

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

  14. Ethylene glycol toxicity presenting with non-anion gap metabolic acidosis.

    Science.gov (United States)

    Soghoian, Sari; Sinert, Richard; Wiener, Sage W; Hoffman, Robert S

    2009-01-01

    Ethylene glycol classically produces an elevated anion gap metabolic acidosis. We report a series of patients with ethylene glycol toxicity with a component of non-anion gap metabolic acidosis without known associated confounding factors. A retrospective review of Poison Control Center records were searched more than 8 years (2000-2007) for ethylene glycol and antifreeze. Cases were reviewed and excluded for miscoding, information calls, animal exposures, or non-ingestion exposures. The bicarbonate gap, or delta ratio (DR), was calculated using the formula: DR = (AG - 12)/[24 - measured serum where anion gap (AG) = [Na(+)] - [Cl(-)] - , all in mEq/l. Non-anion gap metabolic acidosis was considered present when the DR metabolic acidosis at presentation. Their calculated anion gap was 14-28, and measured serum ranged from 2-20 mEq/l. A normal anion gap was present in two patients who presented with non-anion gap metabolic acidosis. The DR ranged from 0.28-0.95. Seven out of 14 patients with non-anion gap metabolic acidosis had elevated serum [Cl(-)]. In the other cases, no explanation for the non-anion gap metabolic acidosis could be determined. The absence of a significant anion gap elevation in the setting of metabolic acidosis after ethylene glycol ingestion without other confounding factors (such as ethanol, lithium carbonate or bromide) has not previously been recognized. Clinicians should be aware of the potential for non-anion gap metabolic acidosis in patients with ethylene glycol toxicity, and should not exclude the diagnosis in patients who present with a non-anion gap metabolic acidosis. Further study is needed to determine the mechanisms by which this occurs.

  15. Selective recognition of sulfate anions by a cyclopeptide-derived receptor in aqueous phosphate buffer.

    Science.gov (United States)

    Schaly, Astrid; Belda, Raquel; García-España, Enrique; Kubik, Stefan

    2013-12-20

    A cyclopeptide-based anion receptor containing alternating 6-aminopicolinic acid and substituted (4R)-4-aminoproline subunits with appended β-alanine residues binds sulfate anions in water. Importantly, appreciable sulfate binding is even observed in phosphate buffer, hence in the presence of anions of similar structure but with a different degree of protonation. The cause for the high selectivity of this receptor is related to the mode of action of the sulfate-binding protein.

  16. Effect of interlayer anions on [NiFe]-LDH nanosheet water oxidation activity

    OpenAIRE

    Hunter, B. M.; Hieringer, W.; Winkler, J.R.; Gray, H B; Müller, A. M.

    2016-01-01

    We synthesized nickel–iron layered double hydroxide ([NiFe]-LDH) nanosheets with different interlayer anions to probe their role in water oxidation catalysis. In alkaline electrolyte in ambient air, carbonate rapidly replaced other interlayer anions and catalytic activity was highest. Electrocatalytic water oxidation in virtually carbonate-free alkaline electrolyte revealed that activity was a function of anion basicity. Our [NiFe]-LDH nanosheets, prepared by pulsed laser ablation in liquids,...

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

    DEFF Research Database (Denmark)

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

    1984-01-01

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

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

    Science.gov (United States)

    Rannulu, Nalaka S.; Cole, Richard B.

    2012-09-01

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

  19. Enhancement of anion binding in lanthanide optical sensors.

    Science.gov (United States)

    Cable, Morgan L; Kirby, James P; Gray, Harry B; Ponce, Adrian

    2013-11-19

    In the design of molecular sensors, researchers exploit binding interactions that are usually defined in terms of topology and charge complementarity. The formation of complementary arrays of highly cooperative, noncovalent bonding networks facilitates protein-ligand binding, leading to motifs such as the "lock-and-key". Synthetic molecular sensors often employ metal complexes as key design elements as a way to construct a binding site with the desired shape and charge to achieve target selectivity. In transition metal complexes, coordination number, structure and ligand dynamics are governed primarily by a combination of inner-sphere covalent and outer-sphere noncovalent interactions. These interactions provide a rich variable space that researchers can use to tune structure, stability, and dynamics. In contrast, lanthanide(III)-ligand complex formation and ligand-exchange dynamics are dominated by reversible electrostatic and steric interactions, because the unfilled f shell is shielded by the larger, filled d shell. Luminescent lanthanides such as terbium, europium, dysprosium, and samarium display many photophysical properties that make them excellent candidates for molecular sensor applications. Complexes of lanthanide ions act as receptors that exhibit a detectable change in metal-based luminescence upon binding of an anion. In our work on sensors for detection of dipicolinate, the unique biomarker of bacterial spores, we discovered that the incorporation of an ancillary ligand (AL) can enhance binding constants of target anions to lanthanide ions by as much as two orders of magnitude. In this Account, we show that selected ALs in lanthanide/anion systems greatly improve sensor performance for medical, planetary science, and biodefense applications. We suggest that the observed anion binding enhancement could result from an AL-induced increase in positive charge at the lanthanide ion binding site. This effect depends on lanthanide polarizability, which can be

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2012-01-01

    Obstructive jaundice occurs in patients suffering from cholelithiasis and from neoplasms affecting the pancreas and the common bile duct. The absorption, distribution and elimination of drugs are impaired during this pathology. Prolonged cholestasis may alter both liver and kidney function. Lactam antibiotics, diuretics, non-steroidal anti-inflammatory drugs, several antiviral drugs as well as endogenous compounds are classified as organic anions. The hepatic and renal organic anion transport pathways play a key role in the pharmacokinetics of these compounds. It has been demonstrated that acute extrahepatic cholestasis is associated with increased renal elimination of organic anions. The present work describes the molecular mechanisms involved in the regulation of the expression and function of the renal and hepatic organic anion transporters in extrahepatic cholestasis, such as multidrug resistance-associated protein 2, organic anion transporting polypeptide 1, organic anion transporter 3, bilitranslocase, bromosulfophthalein/bilirubin binding protein, organic anion transporter 1 and sodium dependent bile salt transporter. The modulation in the expression of renal organic anion transporters constitutes a compensatory mechanism to overcome the hepatic dysfunction in the elimination of organic anions. PMID:23197884

  2. Novel N,N'-Diacylhydrazine-Based Colorimetric Receptors for Selective Sensing of Fluoride and Acetate Anions

    Institute of Scientific and Technical Information of China (English)

    SHI, Da-Qing; WANG, Hai-Ying; LI, Xiao-Yue; YANG, Fang; SHI, Jing-Wen; WANG, Xiang-Shan

    2007-01-01

    Three novel and simple N,N'-diacylhydrazine-based colorimetric receptors have been prepared. The binding properties of the receptors to anions such as F-, Cl-, Br-, AcO-, HSO-4 and H2PO-4 in acetonitrile solution were examined by UV-Vis spectroscopy methods, which show high sensitivity and selectivity to F- and AcO- over other anions. The results indicated that a 1:1 stoichiometry complex was formed between the receptors and the anions, while 1H NMR titrations confirmed hydrogen binding interaction between the receptors and the anions.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  4. Precise, fast, and flexible determination of protein interactions by affinity capillary electrophoresis: part 3: anions.

    Science.gov (United States)

    Xu, Yuanhong; Redweik, Sabine; El-Hady, Deia Abd; Albishri, Hassan M; Preu, Lutz; Wätzig, Hermann

    2014-08-01

    The binding of physiologically anionic species or negatively charged drug molecules to proteins is of great importance in biochemistry and medicine. Since affinity capillary electrophoresis (ACE) has already proven to be a suitable analytical tool to study the influence of ions on proteins, this technique was applied here for comprehensively studying the influence of various anions on proteins of BSA, β-lactoglobulin, ovalbumin, myoglobin, and lysozyme. The analysis was performed using different selected anions of succinate, glutamate, phosphate, acetate, nitrate, iodide, thiocyanate, and pharmaceuticals (salicylic acid, aspirin, and ibuprofen) that exist in the anionic form at physiological pH 7.4. Due to the excellent repeatability and precision of the ACE measurements, not necessarily strong but significant influences of the anions on the proteins were found in many cases. Different influences in the observed bindings indicated change of charge, mass, or conformational changes of the proteins due to the binding with the studied anions. Combining the mobility-shift and pre-equilibrium ACE modes, rapidity and reversibility of the protein-anion bindings were discussed. Further, circular dichroism has been used as an orthogonal approach to characterize the interactions between the studied proteins and anions to confirm the ACE results. Since phosphate and various anions from amino acids and small organic acids such as succinate or acetate are present in very high concentrations in the cellular environment, even weak influences are certainly relevant as well.

  5. Solvent effect on neutral chiral supramolecular assemblies and their distinct receptor behaviour towards anions.

    Science.gov (United States)

    Kumar, Navnita; Khullar, Sadhika; Mandal, Sanjay K

    2015-01-28

    We describe the distinct receptor behaviour of a neutral chiral Cu(ii) complex in dimethylsulfoxide or methanol towards anions, such as F(-), Cl(-), Br(-), I(-) or OAc(-), where F(-) and OAc(-) show the most colorimetric change, through various spectroscopic techniques. Further insights into this at the molecular level come from the single crystal X-ray structures of both dimethylsulfoxide and methanol solvates which show a solvent effect on their supramolecular network formation. Both chromogenic and fluorogenic sensing of the anions indicate a 2 : 1 receptor-anion formation via anion-π as well as hydrogen bonding interactions.

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

    Science.gov (United States)

    Zhao, Limin; Liu, Ge; Zhang, Baofeng

    2016-12-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  8. Subtle anion effects on anion exchange and thermolysis: Square supra-channels via array of sinusoidal coordination polymers

    Science.gov (United States)

    Moon, So Yun; Park, Min Woo; Noh, Tae Hwan; Jung, Ok-Sang

    2013-12-01

    Self-assembly of AgX (X=ClO4-,BF4-) with a new diethylbis(4-pyridyl)silane (L) ligand basically gives rise to a one-dimensional (1D) sinusoidal structure. Weak C-H⋯π interactions between ethyl and pyridyl groups result in the formation of infinite square supra-channel structures via a molecular array of four sinusoidal chains. The supra-channel size is 10.1-10.7 Å with a void cross-section of 2.1-3.1 Å for [Ag(L)](ClO4) and 9.9-10.5 Å with a void cross-section of 2.0-3.0 Å for [Ag(L)](BF4). The supra-channels are occupied by each counteranion. Anion exchange of [Ag(L)](BF4) with NaClO4 occurs smoothly, whereas the reverse anion exchange of [Ag(L)](ClO4) with NaBF4 does not. Calcination of [Ag(L)](ClO4) crystals at 400 °C produces a circle morphology with evolving burned organics, and, at 600 °C, forms network circles consisting of a silver(0)/silver chloride (chlorargyrite)/silicon(IV) oxide composite with a micro-sized convexo-concave surface. In contrast, calcination of [Ag(L)](BF4) crystals at 600 °C produces silver(0) materials without silicon(IV) oxide.

  9. Structural evolution and stabilities of neutral and anionic clusters of lead sulfide: Joint anion photoelectron and computational studies

    Science.gov (United States)

    Koirala, Pratik; Kiran, Boggavarapu; Kandalam, Anil K.; Fancher, Charles. A.; de Clercq, Helen L.; Li, Xiang; Bowen, Kit. H.

    2011-10-01

    The geometric and electronic structures of both neutral and negatively charged lead sulfide clusters, (PbS)n/(PbS)n- (n = 2-10) were investigated in a combined anion photoelectron spectroscopy and computational study. Photoelectron spectra provided vertical detachment energies (VDEs) for the cluster anions and estimates of electron affinities (EA) for their neutral cluster counterparts, revealing a pattern of alternating EA and VDE values in which even n clusters exhibited lower EA and VDE values than odd n clusters up until n = 8. Computations found neutral lead sulfide clusters with even n to be thermodynamically more stable than their immediate (odd n) neighbors, with a consistent pattern also being found in their HOMO-LUMO gaps. Analysis of neutral cluster dissociation energies found the Pb4S4 cube to be the preferred product of the queried fragmentation processes, consistent with our finding that the lead sulfide tetramer exhibits enhanced stability; it is a magic number species. Beyond n = 10, computational studies showed that neutral (PbS)n clusters in the size range, n = 11-15, prefer two-dimensional stacking of face-sharing lead sulfide cubical units, where lead and sulfur atoms possess a maximum of five-fold coordination. The preference for six-fold coordination, which is observed in the bulk, was not observed at these cluster sizes. Taken together, the results show a preference for the formation of slightly distorted, fused cuboids among small lead sulfide clusters.

  10. Mechanism and kinetics for scavenging superoxide anion by progesterone

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  11. Formation of wormlike micelles in anionic surfactant AES aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The growth and structure of anionic micelles of sodium dodecyl trioxyethylene sulfate (AES) in the presence 3+of multivalent counterion Al were investigated by means of dynamic rheological methods. It has been obtained by the measurements of shear viscosity, complex viscosity and dynamic moduli, as well as the application of Cox-Merz rule and Cole-Cole plot that wormlike micelle and network structure could be formed in AES/AlCl3 aqueous solutions.The structure was of a character of nonlinear viscoelastic fluid and departure from the simple Maxwell model. The technique of freeze-fracture transmission electron microscopy (FF-TEM) was also used to confirm the formation of this interesting structure.``

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

    Science.gov (United States)

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

    2012-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-10-04

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

  14. Vertical ionization energies of halogen anions in solution

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

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

  15. Radiation-induced decomposition of anion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Baidak, Aliaksandr [Radiation Laboratory, University of Notre Dame, Notre Dame, IN 46556 (United States); LaVerne, Jay A., E-mail: laverne.1@nd.ed [Radiation Laboratory, University of Notre Dame, Notre Dame, IN 46556 (United States) and Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2010-12-31

    Radiation-induced degradation of the strongly basic anion exchange resin Amberlite{sup TM} IRA400 in NO{sub 3}{sup -}, Cl{sup -} and OH{sup -} forms has been studied. The research focused on the formation of molecular hydrogen in the gamma-radiolysis of water slurries of these quaternary ammonium resins with varying water content. Extended studies with various electron scavengers (NO{sub 3}{sup -}, N{sub 2}O and O{sub 2}) prove an important role of e{sub solv}{sup -} in the formation of H{sub 2} from these resins. An excess production of H{sub 2} in these systems at about 85% water weight fraction was found to be due to trimethylamine, dimethylamine and other compounds that leach from the resin to the aqueous phase. Irradiations with 5 MeV {sup 4}He ions were performed to simulate the effects of {alpha}-particles.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-15

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

  17. Preliminary Testing For Anionic, Cationic and Non-ionic

    Directory of Open Access Journals (Sweden)

    Bokic, Lj.

    2007-11-01

    Full Text Available Detergents present a major environmental problem due to large quantities of surfactants released from laundries. For this reason, it is important to apply an appropriate analytical method for their determination. In this work, we propose two simple, fast and inexpensive analytical methods for anionic, cationic and non-ionic surfactant determination: thin layer chromatography (TLC separation for qualitative screening and quantitative potentiometric determination with ion-selective electrodes. These methods have been chosen because of their many advantages: rapidity, ease of operation, low cost of analysis and a wide variety of TLC application possibilities. The advantage of potentiometric titration is its very high degree of automation and very low detection limits obtained with different ion-selective electrodes applied for different surfactants.

  18. Anionic substituent control of the electronic structure of aromatic nitrenes.

    Science.gov (United States)

    Rau, Nathan J; Welles, Emily A; Wenthold, Paul G

    2013-01-16

    The electronic structures of phenylnitrenes with anionic π-donating substituents are investigated by using mass spectrometry and electronic structure calculations. Reactions of para-CH(2)(-)-substituted phenylnitrene, formed by dissociative deprotonation of p-azidotoluene, with CS(2) and NO indicate that it has a closed-shell singlet ground state, whereas reactions of p-oxidophenylnitrene formed by dissociative deprotonation of p-azidophenol indicate either a triplet ground state or a singlet with a small singlet-triplet splitting. The ground electronic state assignments based on ion reactivity are consistent with electronic structure calculations. The stability of the closed-shell singlet states in nitrenes is shown by Natural Resonance Theory to be very sensitive to the amount of deprotonated-imine character in the wave function, such that large changes in state energies can be achieved by small modifications of the electronic structure.

  19. Anionic access to silylated and germylated binuclear heterocycles.

    Science.gov (United States)

    Boddaert, Thomas; François, Cyril; Mistico, Laetitia; Querolle, Olivier; Meerpoel, Lieven; Angibaud, Patrick; Durandetti, Muriel; Maddaluno, Jacques

    2014-08-04

    A simple access to silylated and germylated binuclear heterocycles, based on an original anionic rearrangement, is described. A set of electron-rich and electron-poor silylated aromatic and heteroaromatic substrates were tested to understand the mechanism and the factors controlling this rearrangement, in particular its regioselectivity. This parameter was shown to follow the rules proposed before from a few examples. Then, the effect of the substituents borne by the silicon itself, in particular the selectivity of the ligand transfer, was studied. Additionally, this chemistry was extended to germylated substrates. A hypervalent germanium species, comparable to the putative intermediate proposed with silicon, seems to be involved. However, a pathway implicating the elimination of LiCH2Cl was observed for the first time with this element, leading to unexpected products of the benzo-oxa (or benzo-aza) germol-type.

  20. IR spectroscopy of gaseous fluorocarbon ions: The perfluoroethyl anion

    Energy Technology Data Exchange (ETDEWEB)

    Crestoni, Maria Elisa; Chiavarino, Barbara [Dipartimento di Chimica e Tecnologie del Farmaco, Universita di Roma ' La Sapienza' , P. le A. Moro 5, I-00185 Roma (Italy); Lemaire, Joel; Maitre, Philippe [Universite Paris Sud, Laboratoire de Chimie Physique - UMR8000 CNRS, Faculte des Sciences - Batiment 350, 91405 Orsay Cedex (France); Fornarini, Simonetta, E-mail: simonetta.fornarini@uniroma1.it [Dipartimento di Chimica e Tecnologie del Farmaco, Universita di Roma ' La Sapienza' , P. le A. Moro 5, I-00185 Roma (Italy)

    2012-04-04

    Highlights: Black-Right-Pointing-Pointer C{sub 2}F{sub 5}{sup -} ions are formed by dissociative electron capture in perfluoropropane. Black-Right-Pointing-Pointer Both their reactivity towards neutrals and IRMPD spectroscopy are investigated. Black-Right-Pointing-Pointer The sampled C{sub 2}F{sub 5}{sup -} ions are best described as covalently bound pentafluoroethyl anions. - Abstract: The first IR spectrum of a perfluorinated carbanion has been obtained in the gas phase by IRMPD spectroscopy. Quantum chemical calculations at the MP2/cc-pVTZ level were performed yielding the optimized geometries and IR spectra for a covalently bound C{sub 2}F{sub 5}{sup -} species and for conceivable loosely bound F{sup -}(C{sub 2}F{sub 4}) complexes. Both the computational results and the IR characterization point to a covalent structure for the assayed species in agreement with the reactivity pattern displayed with selected neutrals.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-07-30

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

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

    Science.gov (United States)

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

    2013-08-14

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

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

    Science.gov (United States)

    Machingauta, Cleopas; Hossenlopp, Jeanne M

    2013-12-01

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

  4. Anionic Forensic Signatures for Sample Matching of Potassium Cyanide Using High Performance Ion Chromatography and Chemometrics

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, Carlos G.; Farmer, Orville T.; Carman, April J.

    2011-01-30

    Potassium cyanide, a known poison, was used a model compound to determine the feasibility of using anionic impurities as a forensic signature for matching KCN samples back to their source. In this study, portions of eight KCN stocks originating from four countries were separately dissolved in water and analyzed by high performance ion chromatography (HPIC) using an anion exchange column and conductivity detection. Sixty KCN aqueous samples were produced from the eight stocks and analyzed for 11anionic impurities. Hierarchal cluster analysis and principal component analysis were used to demonstrate that KCN samples cluster according to source based on the concentrations of their anionic impurities. The F-ratio method and degree-of-class separation (DCS) were used for feature selection on a training set of KCN samples in order to optimize sample clustering. The optimal subset of anions needed for sample classification was determined to be sulfate, oxalate, phosphate, and an unknown anion named unk5. Using K-nearest neighbors (KNN) and the optimal subset of anions, KCN test samples from different KCN stocks were correctly determined to be manufactured in the United States. In addition, KCN samples from stocks manufactured in Belgium, Germany, and the Czech Republic were all correctly matched back to their original stocks because each stock had a unique anionic impurity profile. The application of the F-ratio method and DCS for feature selection improved the accuracy and confidence of sample classification by KNN.

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

    Science.gov (United States)

    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.

  6. Determining the Structure of Oxalate Anion Using Infrared and Raman Spectroscopy Coupled with Gaussian Calculations

    Science.gov (United States)

    Peterson, Karen I.; Pullman, David P.

    2016-01-01

    A laboratory project for the upper-division physical chemistry laboratory is described, and it combines IR and Raman spectroscopies with Gaussian electronic structure calculations to determine the structure of the oxalate anion in solid alkali oxalates and in aqueous solution. The oxalate anion has two limiting structures whose vibrational spectra…

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2012-09-19

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

  9. Novel technology to measure dissolved anions on-site and on-line

    Science.gov (United States)

    Continuous measurements of anions in water offers key insight in to the transport and sources of pollutants such as phosphate and nitrate. We are developing a new technology that can be deployed at remote locations to measure dissolved anions in flowing water over 15-30 minute intervals. The techn...

  10. Anionic forensic signatures for sample matching of potassium cyanide using high performance ion chromatography and chemometrics.

    Science.gov (United States)

    Fraga, Carlos G; Farmer, Orville T; Carman, April J

    2011-01-30

    Potassium cyanide was used as a model toxicant to determine the feasibility of using anionic impurities as a forensic signature for matching cyanide salts back to their source. In this study, portions of eight KCN stocks originating from four countries were separately dissolved in water and analyzed by high performance ion chromatography (HPIC) using an anion exchange column and conductivity detection. Sixty KCN aqueous samples were produced from the eight stocks and analyzed for 11 anionic impurities. Hierarchal cluster analysis and principal component analysis were used to demonstrate that KCN samples cluster according to source based on the concentrations of their anionic impurities. The Fisher-ratio method and degree-of-class separation (DCS) were used for feature selection on a training set of KCN samples in order to optimize sample clustering. The optimal subset of anions needed for sample classification was determined to be sulfate, oxalate, phosphate, and an unknown anion named unk5. Using K-nearest neighbors (KNN) and the optimal subset of anions, KCN test samples from different KCN stocks were correctly determined to be manufactured in the United States. In addition, KCN samples from stocks manufactured in Belgium, Germany, and the Czech Republic were all correctly matched back to their original stocks because each stock had a unique anionic impurity profile. The application of the Fisher-ratio method and DCS for feature selection improved the accuracy and confidence of sample classification by KNN. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Neutral anion receptors; synthesis and evaluation as sensing molecules in chemically modified field effect transistors (CHEMFETs)

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruel, Bianca H.M.; Yigit, Isteyfo; Engbersen, Johan F.J.; Reinhoudt, David N.

    1997-01-01

    new class of anion selective receptors is based on the neutral uranylsalophene building block as Lewis acidic binding site. Additional hydrogen bond accepting or donating moieties near the anion binding site offer the possibility of varying the binding selectivity. Field effect transistors chemicall

  12. CO{sub 2} binding in the (quinoline-CO{sub 2}){sup −} anionic complex

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Jacob D.; Buytendyk, Allyson M.; Wang, Yi; Bowen, Kit H., E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kim, Seong K. [Department of Chemistry, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-06-21

    We have studied the (quinoline-CO{sub 2}){sup −} anionic complex by a combination of mass spectrometry, anion photoelectron spectroscopy, and density functional theory calculations. The (quinoline-CO{sub 2}){sup −} anionic complex has much in common with previously studied (N-heterocycle-CO{sub 2}){sup −} anionic complexes both in terms of geometric structure and covalent bonding character. Unlike the previously studied N-heterocycles, however, quinoline has a positive electron affinity, and this provided a pathway for determining the binding energy of CO{sub 2} in the (quinoline-CO{sub 2}){sup −} anionic complex. From the theoretical calculations, we found CO{sub 2} to be bound within the (quinoline-CO{sub 2}){sup −} anionic complex by 0.6 eV. We also showed that the excess electron is delocalized over the entire molecular framework. It is likely that the CO{sub 2} binding energies and excess electron delocalization profiles of the previously studied (N-heterocycle-CO{sub 2}){sup −} anionic complexes are quite similar to that of the (quinoline-CO{sub 2}){sup −} anionic complex. This class of complexes may have a role to play in CO{sub 2} activation and/or sequestration.

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

    Science.gov (United States)

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

    2010-05-10

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

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

    DEFF Research Database (Denmark)

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

    1984-01-01

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

  15. Secretion of organic anions by hepatocytes : Involvement of homologues of the multidrug resistance protein

    NARCIS (Netherlands)

    Muller, M; Roelofsen, H; Jansen, PLM

    1996-01-01

    The canalicular multispecific organic anion transporter (cMOAT) is one of at least four ATP-dependent transport systems identified so far in the canalicular membrane domain. Using mutant rat strains that lack organic anion secretion, the substrate specificity of cMOAT has been characterized. cMOAT a

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

    Science.gov (United States)

    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.

  17. Specificity of anion-binding in the substrate-pocket ofbacteriorhodopsin

    Energy Technology Data Exchange (ETDEWEB)

    Facciotti, Marc T.; Cheung, Vincent S.; Lunde, Christopher S.; Rouhani, Shahab; Baliga, Nitin S.; Glaeser, Robert M.

    2003-08-30

    The structure of the D85S mutant of bacteriorhodopsin with a nitrate anion bound in the Schiff-base binding site, and the structure of the anion-free protein have been obtained in the same crystal form. Together with the previously solved structures of this anion pump, in both the anion-free state and bromide-bound state, these new structures provide insight into how this mutant of bacteriorhodopsin is able to bind a variety of different anions in the same binding pocket. The structural analysis reveals that the main structural change that accommodates different anions is the repositioning of the polar side-chain of S85. On the basis of these x-ray crystal structures, the prediction is then made that the D85S/D212N double mutant might bind similar anions and do so over a broader pH range than does the single mutant. Experimental comparison of the dissociation constants, K{sub d}, for a variety of anions confirms this prediction and demonstrates, in addition, that the binding affinity is dramatically improved by the D212N substitution.

  18. Synthesis and Anion Recognition of A Novel Tetraamides Calix [4 ] (aza) crown

    Institute of Scientific and Technical Information of China (English)

    MEI Gong-Xiong; MEN Ling-Zhi; HE Yong-Bing

    2003-01-01

    @@ Anion recognitions have attracted considerable attention in supramolecular chemistry because of its possible ap plication in the field of biology and environment. [1] In recent years, considerable efforts have been devoted to the development of anion fluorescent and colorimetric sensors. [2

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

    KAUST Repository

    Zhang, H.

    2013-08-07

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

  20. Synthesis of porous carbon fibers with strong anion exchange functional groups.

    Science.gov (United States)

    Zheng, Weihua; Hu, Jingtian; Han, Zheshen; Wang, Zixing; Zheng, Zhen; Langer, James; Economy, James

    2015-06-18

    Hybrid porous carbon fibers with strong anion-exchangeable functional groups (HACAX) were synthesized by alkylation of pyrolyzed polyacrylonitrile. HACAX exhibits generic stable positively charged functional groups. This expands the applications of porous carbon media for interacting with anions without adjusting pH, such as Cr(vi) adsorption at natural pH.

  1. Mechanisms underlying KCNQ1channel cell volume sensitivity

    DEFF Research Database (Denmark)

    Hammami, Sofia

    Cells are constantly exposed to changes in cell volume during cell metabolism, nutrient uptake, cell proliferation, cell migration and salt and water transport. In order to cope with these perturbations, potassium channels in line with chloride channels have been shown to be likely contributors...... to the process of cell volume adjustments. A great diversity of potassium channels being members of either the 6TM, 4 TM or 2 TM K+ channel gene family have been shown to be strictly regulated by small, fast changes in cell volume. However, the precise mechanism underlying the K+ channel sensitivity to cell...... mechanism of regulation. Besides being regulated by cell volume, KCNQ1 is also modulated by the interaction of the ß subunit KCNE1 giving rise to the cardiac IKs delayed rectifier potassium current. Apart from altering the kinetic characteristics of the KCNQ1 channel current, KCNE1 also augments the KCNQ1...

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Jingchang Zhang; Xuehua Guo; Weiliang Cao

    2007-01-01

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

  4. Switching between Anion-Binding Catalysis and Aminocatalysis with a Rotaxane Dual-Function Catalyst.

    Science.gov (United States)

    Eichstaedt, Katarzyna; Jaramillo-Garcia, Javier; Leigh, David A; Marcos, Vanesa; Pisano, Simone; Singleton, Thomas A

    2017-07-12

    The "off" state for aminocatalysis by a switchable [2]rotaxane is shown to correspond to an "on" state for anion-binding catalysis. Conversely, the aminocatalysis "on" state of the dual-function rotaxane is inactive in anion-binding catalysis. Switching between the different states is achieved through the stimuli-induced change of position of the macrocycle on the rotaxane thread. The anion-binding catalysis results from a pair of triazolium groups that act together to CH-hydrogen-bond to halide anions when the macrocycle is located on an alternative (ammonium) binding site, stabilizing the in situ generation of benzhydryl cation and oxonium ion intermediates from activated alkyl halides. The aminocatalysis and anion-binding catalysis sites of the dual-function rotaxane catalyst can be sequentially concealed or revealed, enabling catalysis of both steps of a tandem reaction process.

  5. Dual Spectroscopic Responses of Pyridinium Hemicyanine Dyes to Anions%Dual Spectroscopic Responses of Pyridinium Hemicyanine Dyes to Anions

    Institute of Scientific and Technical Information of China (English)

    Xie, Puhui; Guo, Fengqi; Zhang, Dasheng; Zhang, Lei

    2011-01-01

    The absorption and fluorescence spectroscopic responses of three pyridinium hemicyanine dyes to anions F , Cl , Br , I-, H2P02, HS04 and OAc- were investigated. At lower concentrations of OAc- (less than 1 equiv.), both the absorption and the fluorescence intensities of 1--3 were more effectively changed than F at iden- tical concentrations. At higher concentrations of OAc (more than 1 equiv.), the interaction was opposite for each compound. 1H NMR results indicated the interaction between 1, 2 or 3 and F- proceeded through hydrogen bonding. The results showed that these dyes are promising to develop dual fluorescence and chromogenic chemo- sensors toward F- and OAc- according to the subtle difference in the affinity of F and OAc .

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

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Robert [National Energy Technology Laboratory; Damodaran, Krishnan [Department of Chemistry, University of Pittsburgh; Luebke, David [National Energy Technology Laboratory; Nulwala, Hunaid [National Energy Technology Laboratory

    2013-04-18

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  8. Syntheses and structural characterizations of anionic borane-capped ammonia borane oligomers: evidence for ammonia borane H2 release via a base-promoted anionic dehydropolymerization mechanism.

    Science.gov (United States)

    Ewing, William C; Marchione, Allegra; Himmelberger, Daniel W; Carroll, Patrick J; Sneddon, Larry G

    2011-10-26

    Studies of the activating effect of Verkade's base, 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane (VB), on the rate and extent of H(2) release from ammonia borane (AB) have led to the syntheses and structural characterizations of three anionic aminoborane chain-growth products that provide direct support for anionic dehydropolymerization mechanistic steps in the initial stages of base-promoted AB H(2) release reactions. The salt VBH(+)[H(3)BNH(2)BH(2)NH(2)BH(3)](-) (1) containing a linear five-membered anionic aminoborane chain was produced in 74% yield via the room-temperature reaction of a 3:1 AB/VB mixture in fluorobenzene solvent, while the branched and linear-chain seven-membered anionic aminoborane oligomers VBH(+)[HB(NH(2)BH(3))(3)](-) (2a) and VBH(+)[H(3)BNH(2)BH(2)NH(2)BH(2)NH(2)BH(3)](-) (2b) were obtained from VB/AB reactions carried out at 50 °C for 5 days when the AB/VB ratio was increased to 4:1. X-ray crystal structure determinations confirmed that these compounds are the isoelectronic and isostructural analogues of the hydrocarbons n-pentane, 3-ethylpentane, and n-heptane, respectively. The structural determinations also revealed significant interionic B-H···H-N dihydrogen-bonding interactions in these anions that could enhance dehydrocoupling chain-growth reactions. Such mechanistic pathways for AB H(2) release, involving the initial formation of the previously known [H(3)BNH(2)BH(3)](-) anion followed by sequential dehydrocoupling of B-H and H-N groups of growing borane-capped aminoborane anions with AB, are supported by the fact that 1 was observed to react with an additional AB equivalent to form 2a and 2b.

  9. A Selective Colorimetric Anion Sensor Based on Di(hydroxymethyl) Di-(2-pyrrolyl)methane -TCBQ System

    Institute of Scientific and Technical Information of China (English)

    Yong GUO; Shi Jun SHAO; Jian XU; Yan Pin SHI; Sheng Xiang JIANG

    2004-01-01

    A new class of non-covalent charge-transfer complex for anion sensing, consisting of di(hydroxymethyl) di-(2-pyrrolyl) methane and chloranil (TCBQ) is characterized. The new colorimetric anion sensors can generate visual color change against PO43- and HPO42- anions in EtOH/H2O (1:1 v/v) mixture solution. The dipyrromethane-quinone aggregations may be used for higher selective detection of PO43- than other inorganic anions in water solution.

  10. Durability and Performance of Polystyrene-b-Poly(vinylbenzyl trimethylammonium) Diblock Copolymer and Equivalent Blend Anion Exchange Membranes

    Science.gov (United States)

    2015-01-01

    SECURITY CLASSIFICATION OF: Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion transport in fuel cells. In this study... Anion Exchange Membranes The views, opinions and/or findings contained in this report are those of the author(s) and should not contrued as an official...Copolymer and Equivalent Blend Anion Exchange Membranes Report Title Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion

  11. Supramolecular anion recognition by tetrapyrrolic macrocycles Reconhecimento supramolecular de ânions por macrociclos tetrapirrólicos

    OpenAIRE

    2009-01-01

    Anions represent one of the most important species in the natural world and are involved in many crucial chemical processes. Anion coordination chemistry highlights the complexity and importance of anion recognition in almost conceivable biochemical and environmental chemistry processes. This mini review is intended to present recent results achieved in this field, mainly by calix[4]pyrroles and porphyrins. The synthesis and their ability to interact with anionic species will be discussed.   ...

  12. Impact of SLC6A Transporters in Physiological Taurine Transport at the Blood-Retinal Barrier and in the Liver.

    Science.gov (United States)

    Kubo, Yoshiyuki; Akanuma, Shin-Ichi; Hosoya, Ken-Ichi

    2016-01-01

    Cumulative studies showed that taurine (2-aminoethanesulfonic acid) contributes to a variety of physiological events. Transport study suggested the cellular taurine transport in an Na(+)- and Cl(-)-dependent manner, and the several members of SLC6A family have been shown as taurine transporter. At the inner blood-retinal barrier (BRB), taurine transporter (TauT/SLC6A) is involved in the transport of taurine to the retina from the circulating blood. The involvement of TauT is also suggested in γ-aminobutyric acid (GABA) transport at the inner BRB, and its role is assumed in the elimination of GABA from the retinal interstitial fluid. In the retina, taurine is thought to be a major organic osmolyte, and its influx and efflux through TauT and volume-sensitive organic osmolyte and anion channel (VSOAC) in Müller cells regulate the osmolarity in the retinal microenvironment to maintain a healthy retina. In the liver, hepatocytes take up taurine via GABA transporter 2 (GAT2/SLC6A13, the orthologue of mouse GAT3) expressed at the sinusoidal membrane of periportal hepatocytes, contributing to the metabolism of bile acid. Site-directed mutagenesis study suggests amino acid residues that are crucial in the recognition of substrates by GATs and TauT. The evidence suggests the physiological impact of taurine transporters in tissues.

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

    Science.gov (United States)

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

    1999-03-01

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

  14. Role of anionic charges of periplasmic glucans of Shigella flexneri in overcoming detergent stress.

    Science.gov (United States)

    Bhagwat, Arvind A; Leow, Yi Ning; Liu, Liu; Dharne, Mahesh; Kannan, Porteen

    2012-07-01

    Osmoregulated periplasmic glucans (OPGs) are synthesized by the members of the family Enterobacteriaceae when grown under low osmotic growth conditions. Enteropathogens such as Shigella flexneri spend considerable time outside the host environment such as irrigation waters where low nutrient low osmolarity conditions normally may exist. We recently demonstrated that OPGs of S. flexneri are required for optimal growth under low osmolarity low nutrient conditions. Based on homology of the OPG biosynthesis genes to those of Escherichia coli, the presumptive function of opgC and opgB genes is to add succinate and phosphoglycerol residues respectively on OPGs, rendering them anionic. Using lambda-red recombination procedure, we constructed opgB, opgC, and opgBC mutants of S. flexneri. The mutant strain defective in opgC and opgB genes synthesized neutral OPGs. The OPGs without any anionic charges were beneficial for the organism's growth in hypo-osmotic media. However, with the loss of anionic charges from OPGs, mutants were compromised in their ability to combat stress caused by anionic detergents in hypo-osmotic growth conditions. Cloned wild-type genes opgB, opgC, and opgBC, when mobilized to respective opg mutants, simultaneously restored anionic charges to OPGs and tolerance to detergents. The data indicate that anionic charges on the OPGs contribute towards overcoming the stress caused by anionic detergents such as sodium dodecyl sulfate and sodium deoxycholate.

  15. Mg-Al layered double hydroxide intercalated with porphyrin anions: molecular simulations and experiments.

    Science.gov (United States)

    Kovár, Petr; Pospísil, Miroslav; Káfunková, Eva; Lang, Kamil; Kovanda, Frantisek

    2010-02-01

    Molecular modeling in combination with powder X-ray diffraction (XRD) provided new information on the organization of the interlayer space of Mg-Al layered double hydroxide (LDH) containing intercalated porphyrin anions [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS)]. Anion-exchange and rehydration procedures were used for the preparation of TPPS-containing LDH with an Mg/Al molar ratio of 2. Molecular modeling was carried out in the Cerius(2) and Materials Studio modeling environment. Three types of models were created in order to simulate the experimental XRD patterns of LDH intercalates with a TPPS loading of 70-80% with respect to the theoretical anion exchange capacity (AEC). The models represent single-phase systems with a 100% TPPS loading in the interlayer space (Type 1) and models represent the coexistence of two phases corresponding to the total exchange from 75 to 92% (Type 2). To cover other possible arrangements, models with the coexistence of both TPPS and NO(3)(-) anions in the same interlayer space were calculated (Type 3). The models are described and compared with experimental data. In all cases, guest TPPS anions are tilted with respect to the hydroxide layers, and are horizontally shifted to each other by up to one-half of the TPPS diameter. According to the energy characteristics and simulated XRD, the most probable arrangement is of Type 2, where some layers are saturated with TPPS anions and others are filled with original NO(3)(-) anions.

  16. Utilization of a diol-stationary phase column in ion chromatographic separation of inorganic anions.

    Science.gov (United States)

    Arai, Kaori; Mori, Masanobu; Kozaki, Daisuke; Nakatani, Nobutake; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-12-28

    We describe the ion chromatographic separation of inorganic anions using a diol-stationary phase column (-CH(OH)CH(2)OH; diol-column) without charged functional groups. Anions were separated using acidic eluent as in typical anion-exchange chromatography. The retention volumes of anions on the diol-column increased with increasing H(+) concentration in the eluent. The anion-exchange capacities of diol-columns in the acidic eluent (pH 2.8) were larger than that of zwitterionic stationary phase column but smaller than that of an anion-exchange column. The separation of anions using the diol-column was strongly affected by the interaction of H(+) ions with the diol-functional groups and by the types of the eluents. In particular, the selection of the eluent was very important for controlling the retention time and resolution. Good separation was obtained using a diol-column (HILIC-10) with 5 mM phthalic acid as eluent. The limits of detection at a signal-to-noise ratio of 3 ranged from 1.2 to 2.7 μM with relative standard deviations (RSD, n=5) of 0.04-0.07% for the retention time and 0.4-2.0% for the peak areas. This method was successfully applied to the determination of H(2)PO(4)(-), Cl(-), and NO(3)(-) in a liquid fertilizer sample.

  17. Theoretical Electronic and Rovibrational Studies for Anions of Interest to the DIBs

    CERN Document Server

    Fortenberry, Ryan C

    2013-01-01

    The dipole-bound excited state of the methylene nitrile anion (CH2CN-) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN- and the similar methylene enolate anion, CH2CHO-. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist in the detection of these anions in the ISM, work has also been directed towards predicting vibrational frequencies and spectroscopic constants for these anions through the use of quartic force fields (QFFs). Theoretical rovibrational work on anions has thus far included studies of CH2CN-, C3H-, and is currently ongoing for similar systems.

  18. Computational design of model scaffold for anion recognition based on the 'C(α) NN' motif.

    Science.gov (United States)

    Sheet, Tridip; Ghosh, Suvankar; Pal, Debnath; Banerjee, Raja

    2017-01-01

    The 'novel phosphate binding 'C(α) NN' motif', consisting of three consecutive amino acid residues, usually occurs in the protein loop regions preceding a helix. Recent computational and complementary biophysical experiments on a series of chimeric peptides containing the naturally occurring 'C(α) NN' motif at the N-terminus of a designed helix establishes that the motif segment recognizes the anion (sulfate and phosphate ions) through local interaction along with extension of the helical conformation which is thermodynamically favored even in a context-free, nonproteinaceous isolated system. However, the strength of the interaction depends on the amino acid sequence/conformation of the motif. Such a locally-mediated recognition of anions validates its intrinsic affinity towards anions and confirms that the affinity for recognition of anions is embedded within the 'local sequence' of the motif. Based on the knowledge gathered on the sequence/structural aspects of the naturally occurring 'C(α) NN' segment, which provides the guideline for rationally engineering model scaffolds, we have modeled a series of templates and investigated their interactions with anions using computational approach. Two of these designed scaffolds show more efficient anion recognition than those of the naturally occurring 'C(α) NN' motif which have been studied. This may provide an avenue in designing better anion receptors suitable for various biochemical applications.

  19. Activation/driving force relationships for cyclopropylcarbinyl --> homoallyl-type rearrangements of radical anions.

    Science.gov (United States)

    Chahma, M'hamed; Li, Xiangzhong; Phillips, J Paige; Schwartz, Phillip; Brammer, Larry E; Wang, Yonghui; Tanko, James M

    2005-04-21

    By using direct and indirect electrochemical methods, rate constants (ko) for cyclopropane ring opening of radical anions derived from the one-electron reduction of trans-1-benzoyl-2-phenylcyclopropane, trans-1-benzoyl-2-vinylcyclopropane, 2-methylenecyclopropyl phenyl ketone, spiro[anthracene-9,1'-cyclopropan-10-one], 3-cyclopropylcyclohex-2-en-1-one, and 3-(1-methylcyclopropyl)cyclohex-2-en-1-one were determined. Qualitatively, rate constants for ring opening of these (and other cyclopropyl- and cyclobutyl-containing radical anions) can be rationalized on the basis of the thermodynamic stability of the radical anion, the ability of substituents on the cyclopropyl group to stabilize the radical portion of the distonic radical anion, and the stability of the enolate portion of the distonic radical anion. On the basis of this notion, a thermochemical cycle for estimating deltaG(o) for ring opening was presented. For simple cyclopropyl-containing ketyl anions, a reasonable correlation between log(ko) and deltaG(o) was found, and stepwise dissociative electron transfer theory was applied to rationalize the results. Activation energies calculated with density functional theory (UB3LYP/6-31+G*) correlate reasonably well with measured log(ko). The derived log(ko) and deltaG(o) and log(ko) vs E(a) plots provide the basis for a "calibration curve" to predict rate constants for ring opening of radical anions derived from carbonyl compounds, in general.

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

    Science.gov (United States)

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

    2011-06-02

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

  1. Preparation and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution.

    Science.gov (United States)

    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.

  2. Aqueous extraction of anions from coal and fly ash followed by ion-chromatographic determination

    Directory of Open Access Journals (Sweden)

    Tasić Aleksandra M.

    2016-01-01

    Full Text Available Three different techniques were applied for the aqueous extraction of anions from coal and fly ash: rotary mixer- and ultrasonic-assisted extraction with different duration time, and microwave-assisted extraction at different temperatures. Validation showed that the ion-chromatographic method was suitable for the analysis of anions in coal and fly ash extracts. The variations in the amounts of anions using different extraction times during rotary-assisted extraction were minimal for all investigated anions. The efficiency of ultrasound-assisted extraction of anions from coal depended on the sonication time and was highest at 30 min. The ultrasound-assisted extraction was less efficient for the extraction of anions from fly ash than rotary-assisted extraction. Increase of temperature in the microwave-assisted extraction had a positive effect on the amounts of all anions extracted from coal and sulphate from fly ash, while the amounts of fluoride and chloride in fly ash extracts decreased. The microwave-assisted extraction of coal at 150°C was compared with standard ASTM methods, and results were in good agreement only for chloride. Changes in the pH value and conductivity during ultrasound-assisted extraction were measured in order to explain changes on the surface of coal particles in contact with water and different processes that occur under environmental conditions. [Projekat Ministarstva nauke Republike Srbije, br. 172030, br. 176006 i br. III43009

  3. A versatile, pulsed anion source utilizing plasma-entrainment: Characterization and applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yu-Ju; Lehman, Julia H.; Lineberger, W. Carl, E-mail: wcl@jila.colorado.edu [JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 (United States)

    2015-01-28

    A novel pulsed anion source has been developed, using plasma entrainment into a supersonic expansion. A pulsed discharge source perpendicular to the main gas expansion greatly reduces unwanted “heating” of the main expansion, a major setback in many pulsed anion sources in use today. The design principles and construction information are described and several examples demonstrate the range of applicability of this anion source. Large OH{sup −}(Ar){sub n} clusters can be generated, with over 40 Ar solvating OH{sup −}. The solvation energy of OH{sup −}(Ar){sub n}, where n = 1-3, 7, 12, and 18, is derived from photoelectron spectroscopy and shows that by n = 12-18, each Ar is bound by about 10 meV. In addition, cis– and trans– HOCO{sup −} are generated through rational anion synthesis (OH{sup −} + CO + M → HOCO{sup −} + M) and the photoelectron spectra compared with previous results. These results, along with several further proof-of-principle experiments on solvation and transient anion synthesis, demonstrate the ability of this source to efficiently produce cold anions. With modifications to two standard General Valve assemblies and very little maintenance, this anion source provides a versatile and straightforward addition to a wide array of experiments.

  4. A versatile, pulsed anion source utilizing plasma-entrainment: Characterization and applications

    Science.gov (United States)

    Lu, Yu-Ju; Lehman, Julia H.; Lineberger, W. Carl

    2015-01-01

    A novel pulsed anion source has been developed, using plasma entrainment into a supersonic expansion. A pulsed discharge source perpendicular to the main gas expansion greatly reduces unwanted "heating" of the main expansion, a major setback in many pulsed anion sources in use today. The design principles and construction information are described and several examples demonstrate the range of applicability of this anion source. Large OH-(Ar)n clusters can be generated, with over 40 Ar solvating OH-. The solvation energy of OH-(Ar)n, where n = 1-3, 7, 12, and 18, is derived from photoelectron spectroscopy and shows that by n = 12-18, each Ar is bound by about 10 meV. In addition, cis- and trans- HOCO- are generated through rational anion synthesis (OH- + CO + M → HOCO- + M) and the photoelectron spectra compared with previous results. These results, along with several further proof-of-principle experiments on solvation and transient anion synthesis, demonstrate the ability of this source to efficiently produce cold anions. With modifications to two standard General Valve assemblies and very little maintenance, this anion source provides a versatile and straightforward addition to a wide array of experiments.

  5. Clinical significance of the fractional excretion of anions in metabolic acidosis.

    Science.gov (United States)

    Kim, H Y; Han, J S; Jeon, U S; Joo, K W; Earm, J H; Ahn, C; Kim, S; Lee, J S; Kim, G H

    2001-06-01

    The fractional excretion of anions has been proposed as a new index for the differential diagnosis of metabolic acidosis, identifying the properties of the conjugate base by examining the renal handling of the anion. Here, we investigated clinical significance of the fractional excretion of anions in pathophysiologic diagnosis of metabolic acidosis by measuring urine ammonium (NH4+) excretion, the ratio of A plasma anion gap/delta plasma HCO3- concentration (deltaAG/deltaHCO3-), and fractional excretion of anions in three different groups of metabolic acidosis: acid overproduction (8 patients with lactic acidosis, 8 with diabetic ketoacidosis, 3 with hippuric acidosis following glue sniffing), acid underexcretion (10 patients with chronic renal failure) and normal controls (10 normal volunteers who underwent 3-day NH4Cl loading). As expected, urine NH4+ excretion was higher in overproduction acidosis than in acid-loaded normal controls (88.1 +/- 12.3 vs. 54.0 +/- 3.7 mmol/day, p anions had no difference between overproduction acidosis and chronic renal failure (41.2 +/- 42.8% vs. 41.0 +/- 8.1%). However, the fractional excretion of anions showed significant differences between the subgroups in acid overproduction (lactic acidosis, 4.7 +/- 0.3%; diabetic ketoacidosis, 45.8 +/- 3.1%; hippuric acidosis, 126.0 +/- 14.4%; p anions and the ratio of plasma deltaAG/deltaHCO3- (r2 =-0.89, p anions may provide a useful clue to the differential diagnosis of metabolic acidosis caused by acid overproduction.

  6. Influence of montmorillonites exchange capacity on the basal spacing of cation–anion organo-montmorillonites

    Energy Technology Data Exchange (ETDEWEB)

    Sanqin, Wu [School of Materials Sciences and Technology, China University of Geosciences, No. 29 Xueyuan Road, Beijing, 100083 (China); Zepeng, Zhang, E-mail: unite508@163.com [School of Materials Sciences and Technology, China University of Geosciences, No. 29 Xueyuan Road, Beijing, 100083 (China); Yunhua, Wang [Zhejiang Fenghong New Material Co., Ltd. (China); Libing, Liao [School of Materials Sciences and Technology, China University of Geosciences, No. 29 Xueyuan Road, Beijing, 100083 (China); Jiansheng, Zhang [Tangshan College, Tangshan 063000 (China)

    2014-11-15

    Graphical abstract: This picture shows the distribution of organic modifier (CTAB and SDS) in Mt interlayer and the basal spacing changes of Mt modified by CTAB and SDS. Organic modifier molecule in Mt interlayer is more and more orderly. The basal spacing of Mt is from 1.5 nm to 5 nm as modifier added. - Highlights: • The d{sub 001} of Ca-Mt, R-Na-Mt, Na-Mt modified by CTAB and SDS can reach 5 nm. • It is easier to get cation–anion OMt with greater d{sub 001} if CEC is lower. • The organic molecules distribution in cation–anion OMt was analyzed. • The influence mechanism of Ca-Mt CEC on the d{sub 001} was discussed. - Abstract: With cationic and anionic surfactants cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfonate (SDS) as modifiers, Ca-montmorillonites (Ca-Mt), artificial Na-montmorillonites (R-Na-Mt) and natural Na-montmorillonites (Na-Mt) with different cation exchange capacity (CEC) were modified by solution intercalation method, respectively. Then cation–anion organo-montmorillonites (OMt) were prepared. The influence of CEC on the basal spacing of cation–anion OMt and the influence mechanism were discussed by X-ray diffraction (XRD) and zeta potential testing. The results indicate that the basal spacing of cation–anion OMt is related to CEC. For the same type montmorillonites, the basal spacing of cation–anion OMt decreases with the increase of CEC and it is easier to get cation–anion OMt with greater basal spacing when CEC is lower. Moreover, the CEC of Na-Mt has the greatest influence on the basal spacing of cation–anion OMt.

  7. Adsorption of anionic polyelectrolytes to dioctadecyldimethylammonium bromide monolayers

    Science.gov (United States)

    Engelking, J.; Menzel, H.

    Monolayers of dioctadecyldimethylammonium bromide (DODA) at the air/water interface were used as model for charged surfaces to study the adsorption of anionic polyelectrolytes. After spreading on a pure water surface the monolayers were compressed and subsequently transferred onto a polyelectrolyte solution employing the Fromherz technique. The polyelectrolyte adsorption was monitored by recording the changes in surface pressure at constant area. For poly(styrene sulfonate) and carboxymethylcellulose the plot of the surface pressure as function of time gave curves which indicate a direct correlation between the adsorbed amount and surface pressure as well as a solely diffusion controlled process. In the case of rigid rod-like poly(p-phenylene sulfonate)s the situation is more complicated. Plotting the surface pressure as function of time results in a curve with sigmoidal shape, characterized by an induction period. The induction period can be explained by a domain formation, which can be treated like a crystallization process. Employing the Avrami expression developed for polymer crystallization, the change in the surface pressure upon adsorption of rigid rod-like poly(p-phenylene sulfonate)s can be described.

  8. Cation and anion monitoring in a wastewater treatment pilot project

    Directory of Open Access Journals (Sweden)

    Magda de Almeida

    2015-01-01

    Full Text Available El propósito del tratamiento de aguas residuales es la reutilización del agua.Esta reduce el consumo de agua potable y previene la contaminación del agua de primeruso. La reutilización del agua ya se ha implementado con éxito en diferentes lugares. Lostratamientos que utilizan los humedales artifi ciales son ampliamente estudiados como unaalternativa más económica y ecológica para tratar las aguas residuales. En estos sistemas, elcontrol de especies inorgánicas también es importante. Este estudio ha monitoreado cationes (Na+, K+, Li+ y NH4+ y aniones (SO42-, NO3-, NO2-, Cl- y PO42- en un sistema de humedalesconstruido (CWs, en un sistema de captación de agua de lluvia, en el tratamiento de aguasresiduales y en agua reutilizable fi nal. El monitoreo se llevó a cabo utilizando el análisiscromatográfi co de iones. Los valores de remoción encontrados en CWs fueron: 99,9% K+,NH4+ y SO42-, 52,6% Na+, 89,8% NO3-, 98,2% NO2-, 63,6% Cl- y 96,8% PO42-. Los resultadostambién mostraron que el sistema CWs está adecuado para la eliminación de iones del aguaresidual.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-21

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

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

    Science.gov (United States)

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

    2015-09-01

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

  11. Inactivation of Bacillus Subtilis by Atomic Oxygen Radical Anion

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  12. On Scaling Relations of Organic Antiferromagnets with Magnetic Anions

    Science.gov (United States)

    Shimahara, Hiroshi; Kono, Yuki

    2017-04-01

    We study a recently reported scaling relation of the specific heat of the organic compounds λ-(BETS)2FexGa1-xCl4. This relation suggests that the sublattice magnetization m of the π electrons and the antiferromagnetic transition temperature TN are proportional to x. Note that the scaling relation for TN can be explained by considering the effective interaction between the π electrons via the localized 3d spins on the FeCl4 anions. The effective interaction is analogous to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, but the roles of the conductive electrons and the localized spins are interchanged. Using available energy scales, it is shown that the TN scaling relation indicates that the system is in the vicinity of the quantum critical point. It is argued that the scaling relation for m at low temperatures, i.e., below TN but excluding temperatures in the vicinity of TN, indicates that the mismatch between the Fermi surface and that shifted by the nesting vector is large, at least for a large part of the Fermi surface. We also discuss the scaling relation near TN.

  13. Regulation of renal peripheral benzodiazepine receptors by anion transport inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Basile, A.S.; Lueddens, W.M.; Skolnick, P.

    1988-01-01

    The in vitro and in vivo regulation of (/sup 3/H)Ro 5-4864 binding to peripheral benzodiazepine receptors (PBR) by ion transport/exchange inhibitors was studied in the kidney. The potencies of 9-anthroic acid, furosemide, bumetanide, hydrochlorothiazide and SITS as inhibitors of (/sup 3/H)Ro 5-4864 binding to renal membranes were consistent with their actions as anion transport inhibitors (Ki approx. = 30 - 130 ..mu..M). In contrast, spironolactone, amiloride, acetazolamide, and ouabain were less potent (Ki=100-1000 ..mu..M). Administration of furosemide to rats for five days resulted in a profound diuresis accompanied by a significant increase in PBR density (43%) that was apparent by the fifth day of treatment. Administration of hydrochlorothiazide or Ro 5-4864 for five days also caused diuresis and increased renal PBR density. Both the diuresis and increased density of PBR produced by Ro 5-4864 were blocked by coadministration of PK 11195, which alone had no effect on either PBR density or urine volume. The equilibrium binding constants of (/sup 3/H)Ro 5-4864 to cardiac membranes were unaffected by administration of any of these drugs. These findings suggest that renal PBR may be selectively modulated in vivo and in vitro by administration of ion transport/exchange inhibitors. 36 references, 4 tables.

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

    Energy Technology Data Exchange (ETDEWEB)

    Traboulsi, A. [CEA Marcoule, DEN/DTCD/SPDE/LCFI, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); E.A. LISA – METICA, Aix Marseille Université, Pôle de l’Etoile, case 451, 13397 Marseille Cedex 20 (France); Labed, V., E-mail: veronique.labed@cea.fr [CEA Marcoule, DEN/DTCD/SPDE/LCFI, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Dauvois, V. [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91191 Gif sur Yvette Cedex (France); Dupuy, N.; Rebufa, C. [E.A. LISA – METICA, Aix Marseille Université, Pôle de l’Etoile, case 451, 13397 Marseille Cedex 20 (France)

    2013-10-01

    Radiation-induced decomposition of Amberlite IRA400 anion exchange resin in hydroxide form by gamma radiolysis has been studied at various doses in different atmospheres (anaerobic, anaerobic with liquid water, and aerobic). The effect of these parameters on the degradation of ion exchange resins is rarely investigated in the literature. We focused on the radiolysis gases produced by resin degradation. When the resin was irradiated under anaerobic conditions with liquid water, the liquid phase over the resin was also analyzed to identify any possible water-soluble products released by degradation of the resin. The main products released are trimethylamine (TMA), molecular hydrogen (H{sub 2g}) and carbon dioxide (CO{sub 2g}). TMA and H{sub 2g} are produced in all the irradiation atmospheres. However, TMA was in gaseous form under anaerobic and aerobic conditions and in aqueous form in presence of liquid water. In the latter conditions, TMA{sub aq} was associated with aqueous dimethylamine (DMA{sub aq}), monomethylamine (MMA{sub aq}) and ammonia (NH{sub 4}{sup +}{sub aq}). CO{sub 2g} is formed in the presence of oxygen due to oxidation of organic compounds present in the system, in particular the degradation products such as TMA{sub g}.

  15. The hydrothermolysis of the picrate anion: Kinetics and mechanism

    Science.gov (United States)

    Ross, D.S.; Jayaweera, I.

    2002-01-01

    The hydrothermolysis of the picrate anion in aqueous solution has been studied at 260-325??C in liquid water. At starting pH values above 12, the disappearance of picrate begins immediately and is first order in OH-. At lower pH, there is an induction period preceding the disappearance, and over the pH range 6.7-11.9 there is no pH dependence in the developed reaction phase. Added borate and silicate salts promote the reaction, suggesting their acting as nucleophiles at hydrothermal conditions. Nitrite is an initial product, while acetate is a final product and reflective of a vigorous oxidative sequence consuming the intermediate products. A reaction sequence consistent with the results at the lower pH includes initiation of a chain process by displacement of nitrite by water, followed by nucleophilic displacement of nitrite by nitrite such that a nitro group is replaced by an O-N=O group. The ester then rapidly hydrolyzes, and the net reaction is the production of an additional nitrite with each cycle. A simple modeling of this system satisfactorily fits the experimental findings. ?? 2002 Elsevier Science B.V. All rights reserved.

  16. Adsorption of Anionic Dyes on the Biopolymer Chitin

    Directory of Open Access Journals (Sweden)

    Longhinotti Elisane

    1998-01-01

    Full Text Available The adsorption of the anionic dyes orange IV, orange G and xylenol orange on chitin was studied, employing the Langmuir isotherm. The adsorption parameters were determined utilizing various linear regressions of the isotherm. The results showed that the adsorption capacity is dependent on pH. In acid pH, the polymer amino groups are protonated and the polymer chain is positively charged, with a predominance of adsorption through ion exchange. Van der Waals adsorption, as well as adsorption through hydrogen bonding, is also likely to occur to some extent. For xylenol orange, a linear regression was found, with an angular coefficient of 0.726 L mg-1. The temperature increase reduces adsorption capacity by chitin, due to the enhancement of the desorption step in the mechanism. deltaH values of -10.9 kJ mol-1 for orange G and -28.9 kJ mol-1 for orange IV prove the physical nature of the adsorption by these dyes on the chitin surface.

  17. Improved immunoadsorption procedure with anion-exchange bacterial cell columns.

    Science.gov (United States)

    McKinney, R M; Thacker, L; Wong, M C; Hebert, G A

    1978-01-01

    Bacterial cell columns for immunoadsorption were prepared with Streptococcus cells and triethylaminoethyl cellulose (Cellex-T) matrix material as a model system. Good column flow properties and satisfactory retention of the cells were obtained with ratios as high as 2 ml of packed cells/3 g dry weight of cellulose. Anion-exchange fractionation of whole serum by the Cellex-T was prevented by using 0.25 M NaCl in the developing buffer. Antibodies were adsorbed directly from whole serum and recovered in high yield by desorption at pH 2.3. Pre-exposing bacterial cells to formalin and washing them with acetone was necessary to ensure that they remained on the columns. One strain of Streptococcus salivarius (SS 908) was satisfactorily retained on a column only after cells were labeled with fluorescein isothiocyanate and washed with acetone. The means by which Cellex-T retains bacterial cells appears to be a combination of electronic attraction and physical entrapment.

  18. Gold recovery by galvanic stripping of an anionic organic extractant

    Directory of Open Access Journals (Sweden)

    Lacerda D.F.C.

    2001-01-01

    Full Text Available The galvanic stripping technique for metal recovery uses commercial organic extractants containing a metal to be recovered. The organic phase is placed in contact with a solid metal reducer that allows electrochemical reactions to occur. One product of these reactions is a metal layer deposited on the surface of the reducer consisting of reduced species desorbed from the organic phase. Another product is metal ions from the reducer adsorbed onto the organic phase. This work presents results for gold recovery by galvanic stripping of strong-base anionic extractants of a quaternary amine salt, ALIQUAT336®, in xylene using solid zinc as the metal reducer. The parameters studied were contact time for the organic phase containing gold and the samples of the reducing zinc metal, temperature of the system, gold concentration in the organic phase and type of stirring used in the galvanic stripping system. Experiments showed results higher than 28% of gold recovery and an adherent film of gold on the zinc surface. The Arrhenius plot for gold recovery from the organic extractant suggests a change in the rate- controlling step from mixed control to diffusion control with increasing temperature in the range of 20 to 50ºC.

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

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.

    2016-03-03

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

  20. Superoxide anion production by neutrophils in myelodysplastic syndromes (preleukemia.

    Directory of Open Access Journals (Sweden)

    Takahashi,Isao

    1988-02-01

    Full Text Available Superoxide anion (O2- production by neutrophils from 14 untreated patients with acute nonlymphocytic leukemia (ANLL was significantly less than that of healthy controls (4.93 +/- 1.99 vx 6.20 +/- 1.53 nmol/min/10(6 neutrophils, p less than 0.05. In 10 patients with myelodysplastic syndrome (MDS, however, it was not significantly different from the control level although 6 of the 10 patients had low levels, when individual patients were compared with the lower limit of the control range. An inverse correlation between the O2- production of neutrophils and the percentage of leukemic cells in the marrow existed in ANLL (r = -0.55, p less than 0.01, but not in MDS. Three of 4 MDS patients who died of pneumonia prior to leukemic conversion showed a low level of O2- production. The impaired O2- production by neutrophils from some MDS patients, probably due to the faulty differentiation from leukemic clones, may be one of the causes of enhanced susceptibility to infection.

  1. Photoinduced Dynamics of Neutral, Cationic, and Anionic Species

    DEFF Research Database (Denmark)

    Stephansen, Anne Boutrup

    In contrast to ground state (thermal) chemistry where internal energy is statistically distributed among the molecular degrees of freedom, photo-activation of a reaction entails initial localization of the internal energy in a highly non-statistical manner. The result is often reaction rates fast...... impact on the evolution of the ensuing reaction. The diversity of the processes studied illustrates the versatility of the experimental method as a means to increase knowledge on the complex interplay between structural dynamics and (photo)-reactivity....... than those predicted by statistical models, but also a more critical dependence between molecular structure and (photo)-reactivity. This thesis presents a collection of studies of various types of photoinduced processes in neutral, anionic, or cationic molecular species as introduced below....... The investigations have primarily employed femtosecond time-resolved photoionization or photodetachment techniques. Intersystem crossing (ISC) in neutral organic species is conventionally assumed to be slow due to the spin-forbidden nature of the process; this assumption has been challenged during the past decade...

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

    Science.gov (United States)

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

    2016-01-01

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

  3. Endomorphins 1 and 2 modulate chemotaxis, phagocytosis and superoxide anion production by microglia.

    Science.gov (United States)

    Azuma, Y; Ohura, K; Wang, P L; Shinohara, M

    2001-09-03

    We evaluate the role of endomorphins 1 and 2 on microglial functions. Endomorphins 1 and 2 blocked phagocytosis of Escherichia coli. In addition, both markedly inhibited chemotaxis toward zymosan-activated serum. In contrast, when microglia was preincubated with these endomorphins, followed by incubation with LPS before stimulation with phorbol 12-myristate 13-acetate (PMA) at 200 nM, they potentiated superoxide anion production. Furthermore, when microglia was preincubated with these endomorphins together with PMA at 20 nM, followed by stimulation with PMA at 200 nM, superoxide anion production was potentiated. These results suggest that endomorphins 1 and 2 modulate phagocytosis, chemotaxis and superoxide anion production by microglia.

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Indian Academy of Sciences (India)

    R Anbarasan; W D Lee; S S Im

    2005-04-01

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

  6. Aniosotropically organized LDH on PVDF: a geometrically templated electrospun substrate for advanced anion conducting membranes.

    Science.gov (United States)

    Sailaja, G S; Zhang, Peilin; Anilkumar, Gopinathan M; Yamaguchi, Takeo

    2015-04-01

    A bioinspired geometric templating of an electrospun PVDF substrate with hexagonal platelets of Mg-Al layered double hydroxide (LDH), an intrinsic anion conductor, is presented. The distinctive morphology restructures the internal pore geometry and modulates the dynamic wetting profile of PVDF, transforming it into a highly functional substrate for SAFC anion conducting membranes. The membrane fabricated with PVDF-LDH substrate exhibited exceptionally high durability (>140 °C), high anionic conductivity, ion exchange capacity (IEC), restricted swelling, and improved tensile strength, overcoming critical challenges associated with PVDF electrospun substrates and validating its immense potential as a high-temperature-stable and durable substrate for advanced fuel cell membrane applications.

  7. Crystal structures and phase-transition dynamics of cobaltocenium salts with bis(perfluoroalkylsulfonyl)amide anions: remarkable odd-even effect of the fluorocarbon chains in the anion.

    Science.gov (United States)

    Mochida, Tomoyuki; Funasako, Yusuke; Inagaki, Takashi; Li, Meng-Jiao; Asahara, Kotaro; Kuwahara, Daisuke

    2013-05-10

    Crystal structures and thermal properties of cobaltocenium salts with bis(perfluoroalkylsulfonyl)amide (C(n)F2(n+1)SO2)2N anions [n = 0 (1), 1 (1 a), 2 (1 b), 3 (1 c), and 4 (1 d)] and the 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonylamide anion (2) were investigated. In these solids, the cations are surrounded by four anions around their C5 axis, and stacking of these local structures forms two kinds of assembled structures. In the salts with even n (1, 1 b, and 1 d), the cation and anion are arranged alternately to form mixed-stack columns in the crystal. In contrast, in the salts with odd n (1 a and 1 c), the cations and anions independently form segregated-stack columns. An odd-even effect was also observed in the sum of the phase-change entropies from crystal to melt. All of the salts exhibited phase transitions in the solid state. The phase transitions to the lowest-temperature phase in 1, 1 a, and 2 are accompanied by order-disorder of the anions and symmetry lowering of the space group, which results in the formation of an ion pair. Solid-state (13)C NMR measurements on 1 a and 1 b revealed enhanced molecular motions of the cation in the higher-temperature phases. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. The Production of Polycyclic Aromatic Hydrocarbon Anions in Inert Gas Matrices Doped with Alkali Metals. Electronic Absorption Spectra of the Pentacene Anion (C22H14(-))

    Science.gov (United States)

    Halasinski, Thomas M.; Hudgins, Douglas M.; Salama, Farid; Allamandola, Louis J.; Mead, Susan (Technical Monitor)

    1999-01-01

    The absorption spectra of pentacene (C22H14) and its radical cation (C22H14(+)) and anion (C22H14(-)) isolated in inert-gas matrices of Ne, Ar, and Kr are reported from the ultraviolet to the near-infrared. The associated vibronic band systems and their spectroscopic assignments are discussed together with the physical and chemical conditions governing ion (and counterion) production in the solid matrix. In particular, the formation of isolated pentacene anions is found to be optimized in matrices doped with alkali metal (Na and K).

  9. Poly(ethylene oxide)-bonded stationary phase for separation of inorganic anions in capillary ion chromatography.

    Science.gov (United States)

    Linda, Roza; Lim, Lee Wah; Takeuchi, Toyohide

    2013-06-14

    A tosylated-poly(ethylene oxide) (PEO) reagent was reacted with primary amino groups of an aminopropylsilica packing material (TSKgel NH2-60) in acetonitrile to form PEO-bonded stationary phase. The reaction was a single and simple step reaction. The prepared stationary phase was able to separate inorganic anions. The retention behavior of six common inorganic anions on the prepared stationary phase was examined under various eluent conditions in order to clarify its separation/retention mechanism. The elution order of the tested anions was iodate, bromate, bromide, nitrate, iodide, and thiocyanate, which was similar as observed in common ion chromatography. The retention of inorganic anions could be manipulated by ion exchange interaction which is expected that the eluent cation is coordinated among the PEO chains and it works as the anion-exchange site. Cations and anions of the eluent therefore affected the retention of sample anions. We demonstrated that the retention of the analyte anions decreased with increasing eluent concentration. The repeatability of retention time for the six anions was satisfactory on this column with relative standard deviation values from 1.1 to 4.3% when 10mM sodium chloride was used as the eluent. Compared with the unmodified TSKgel NH2-60, the prepared stationary phase retained inorganic anions more strongly and the selectivity was also improved. The present stationary phase was applied for the determination of inorganic anions contained in various water samples.

  10. Inhibitory effects of cardols and related compounds on superoxide anion generation by xanthine oxidase.

    Science.gov (United States)

    Masuoka, Noriyoshi; Nihei, Ken-ichi; Maeta, Ayami; Yamagiwa, Yoshiro; Kubo, Isao

    2015-01-01

    5-Pentadecatrienylresorcinol, isolated from cashew nuts and commonly known as cardol (C₁₅:₃), prevented the generation of superoxide radicals catalysed by xanthine oxidase without the inhibition of uric acid formation. The inhibition kinetics did not follow the Michelis-Menten equation, but instead followed the Hill equation. Cardol (C₁₀:₀) also inhibited superoxide anion generation, but resorcinol and cardol (C₅:₀) did not inhibit superoxide anion generation. The related compounds 3,5-dihydroxyphenyl alkanoates and alkyl 2,4-dihydroxybenzoates, had more than a C9 chain, cooperatively inhibited but alkyl 3,5-dihydroxybenzoates, regardless of their alkyl chain length, did not inhibit the superoxide anion generation. These results suggested that specific inhibitors for superoxide anion generation catalysed by xanthine oxidase consisted of an electron-rich resorcinol group and an alkyl chain having longer than C9 chain.

  11. Graphite oxide-intercalated anionic clay and its decomposition to graphene-inorganic material nanocomposites.

    Science.gov (United States)

    Nethravathi, C; Rajamathi, Jacqueline T; Ravishankar, N; Shivakumara, C; Rajamathi, Michael

    2008-08-05

    A graphite oxide-intercalated anionic clay (nickel zinc hydroxysalt) has been prepared using the aqueous colloidal dispersions of negatively charged graphite oxide sheets and aminobenzoate-intercalated anionic clay layers as precursors. When the two colloidal dispersions are reacted, the interlayer aminobenzoate ions are displaced from the anionic clay and the negatively charged graphite oxide sheets are intercalated between the positively charged layers of the anionic clay. The thermal decomposition of the intercalated solid at different temperatures yields graphene-metal oxide/metal nanocomposites. Electron microscopic analysis of the composites indicates that the nanoparticles are intercalated between the layers of graphite in many regions of these solids although the graphite layers are largely exfoliated and not stacked well together.

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

    Science.gov (United States)

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

    2005-01-01

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

  13. Pulp response of anionic lyophilized collagen matrix with or without hydroxyapatite after pulpotomy in dog's teeth

    Directory of Open Access Journals (Sweden)

    Léa Assed Bezerra da Silva

    2006-06-01

    Full Text Available The aim of the present study was to evaluate histologically the pulp response of anionic lyophilized collagen matrix with or without hydroxyapatite as a biomaterial pulp-capping agent in pulpotomy of dogs' teeth. Sixty pre-molar roots from three dogs were used. After pulpotomy, the remaining pulp tissue was capped with one of the following materials: Group I (20 roots: anionic lyophilized collagen matrix; Group II (20 roots: anionic lyophilized collagen matrix associated with hydroxyapatite; Group III (10 roots: calcium hydroxide (p.a. paste in saline; Group IV (10 roots: zinc oxide eugenol cement. After 90 days the animals were killed by anesthetic overdose and the teeth were removed and submitted to histological processing. According to the histopathological results, we concluded that the zinc oxide eugenol cement and anionic lyophilized collagen matrix with or without hydroxyapatite did not present satisfactory pulp response and that calcium hydroxide is the suitable material for pulpotomy.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

  16. Competing reactions of CO2 with cations and anions in azolide ionic liquids.

    Science.gov (United States)

    Gohndrone, Thomas R; Bum Lee, Tae; DeSilva, M Aruni; Quiroz-Guzman, Mauricio; Schneider, William F; Brennecke, Joan F

    2014-07-01

    We show that phosphonium azolide ionic liquids of interest for CO2 capture applications react with CO2 both through the normal anion channel and, at elevated temperatures, through a previously unrecognized cation channel. The reaction is caused by an interaction between the anion and cation that allows proton transfer, and involves a phosphonium ylide intermediate. The cation reaction can be mitigated by using ammonium rather than phosphonium cations. Thus, phosphonium and ammonium cations paired with aprotic heterocyclic anions (AHAs) react with CO2 through different mechanisms at elevated temperatures. This work shows that careful consideration of both physical properties and chemical reactivity of ILs based on AHA anions is needed when designing ionic liquids for CO2 separations.

  17. Synthesis and anion recognition of neutral receptors based on multiamide calix[4]arene

    Institute of Scientific and Technical Information of China (English)

    LIU; Shunying; WANG; Fajun; WEI; Lanhua; XIAO; Wang; MENG

    2004-01-01

    Two multiamide calix[4]arenes (5, 6) were synthesized and characterized by IR, 1H NMR, MS and elemental analysis. The binding properties of receptors with some anions (p-O2NPhOPO2-3, p-O2NPhO-, H2PO-4, Ac-, Cl-, Br- and I-) were studied by UV-Vis spectra. The results indicate that the tetraamide calix[4]arenes (5, 6) have a good selectivity to the anions containing aromatic ring (p-O2NPhOPO32 , p-O2NPhO-). The 1 : 1 complexes between host and guest were formed through multiple hydrogen bonding and π-π interactions. The hosts 5 and 6also show a definite binding ability for the anions (H2 PO-4, Ac-, Cl-) that have no ultraviolet absorption, which provides a simple method of spectrum detection for these anions.

  18. Quantitative analysis of anions in glycosaminoglycans and application in heparin stability studies.

    Science.gov (United States)

    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.

  19. Photostimulated SRN 1 Reactions of Benzyl Chloride with Carbazolyl Nitrogen Anion

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The photostimulated reactions of benzyl chloride with carbazolyl nitrogen anion in dimethyl sulfoxide gave 9-benzylcarbazole and 3-benzylcarbazole.The reactions are suggested in term of SRN1 mechanism of nucleophilic substitution.

  20. Voltammetric Studies on Heteropoly Phosphotungstovanadate Anions Across the Liquid/Liquid Interface

    Institute of Scientific and Technical Information of China (English)

    LU Xiao-quan

    2003-01-01

    Electrochemical transfer behavior of VⅤW11-VⅤ3W9 heteropoly anions on the water/nitrobenzene interface was investigated by means of cyclic voltammetry. The effect of the solution acidity on the transfer behavior and the stable pH range for the heteropoly anions were studied. The stability of mixed tungstovanadate decreases with increasing the number of vanadium atoms. The main transfer species within the potential window have the negative charges of 4 and the transfer process is diffusion-controlled. The apparent transfer potential ΔwoΨ0 and the free energy ΔG0 w→otr for the heteropoly anions can be obtained from the experimental data. For the different anions, the ΔwoΨ1/2-pH relationship can be expressed as: ΔwoΨ1/2=constant-53pH.

  1. Synthesis of Schiff Base Bearing Phenolic Hydroxy Group and Its Anion Recognition

    Institute of Scientific and Technical Information of China (English)

    Ge Liu; Ling Gao

    2011-01-01

    A new anion receptor bearing phenolic hydroxy group based on 3,5-ditertbutylsalicylaldehyde-p-nitrophenylhydrazone (1) was designed and synthesized.Upon addition of AcO- and F-, the receptor exhibited visible color changes from deep yellow to purple. However, no obvious color changes were observed on addition of the other anions tested (H2PO4-, Cl-, Br-, I-). The binding properties of the receptor with anions such as AcO- and F- were investigated by UV-Vis and fluorescent titrations. The result indicated that the receptor 1 had a higher affinity to AcO- and F- and a 1∶1 host-guest complex was formed through H-bond interactions between 1 and anions.

  2. Anion exchange kinetics of nanodimensional layered metal hydroxides: use of isoconversional analysis.

    Science.gov (United States)

    Majoni, Stephen; Hossenlopp, Jeanne M

    2010-12-16

    Anion exchange reactions of nanodimensional layered metal hydroxide compounds are utilized to create materials with targeted physical and chemical properties and also as a means for controlled release of intercalated anions. The kinetics of this important class of reaction are generally characterized by model-based approaches. In this work, a different approach based on isothermal, isoconversional analysis was utilized to determine effective activation energies with respect to extent of reaction. Two different layered metal hydroxide materials were chosen for reaction with chloride anions, using a temperature range of 30-60 °C. The concentrations of anions released into solution and the changes in polycrystalline solid phases were evaluated using model-based (Avrami-Erofe'ev nucleation-growth model) and model-free (integral isoconversional) methods. The results demonstrate the utility of the isoconversional approach for identifying when fitting to a single model is not appropriate, particularly for characterizing the temperature dependence of the reaction kinetics.

  3. A novel anion interstitial defect structure in zinc-blende materials: A first-principles study

    Science.gov (United States)

    Yin, Yuan; Chen, Guangde; Ye, Honggang; Duan, Xiangyang; Zhu, Youzhang; Wu, Yelong

    2016-05-01

    The low-formation energy structure of anion interstitial defect in zinc-blende materials is usually identified as the tetrahedron central structure where the anion interstitial atom is surrounded by four countercation atoms. A line-type anion interstitial defect structure AD_il , however, is found to be lower in energy than the tetrahedron central anion interstitial defect structure by first-principles calculations. By analyzing the structural and electronical characters of this line-type defect in relative compounds of zinc-blende materials, we attribute this to the electronegativity shift trends and the bond forming, which lead to the hybridization types varying from sp 3 to sp-like and ending at sp.

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

    Science.gov (United States)

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

    2015-11-01

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

  5. Structures and energies of the radicals and anions generated from chlorpyrifos.

    Science.gov (United States)

    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.

  6. L-shaped benzimidazole fluorophores: synthesis, characterization and optical response to bases, acids and anions.

    Science.gov (United States)

    Lirag, Rio Carlo; Le, Ha T M; Miljanić, Ognjen Š

    2013-05-14

    Nine L-shaped benzimidazole fluorophores have been synthesized, computationally evaluated and spectroscopically characterized. These "half-cruciform" fluorophores respond to bases, acids and anions through changes in fluorescence that vary from moderate to dramatic.

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

    Science.gov (United States)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  9. Transesterification of propylene glycol methyl ether in chromatographic reactors using anion exchange resin as a catalyst.

    Science.gov (United States)

    Oh, Jungmin; Sreedhar, Balamurali; Donaldson, Megan E; Frank, Timothy C; Schultz, Alfred K; Bommarius, Andreas S; Kawajiri, Yoshiaki

    2016-09-30

    Reactive chromatography using an anion exchange resin is proposed for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) with ethyl acetate to produce propylene glycol methyl ether acetate (DOWANOL™ PMA). This reaction is studied in batch and chromatographic reactors catalyzed by an anion exchange resin. Several anion exchange resins are tested and compared based on the performance of resin as an adsorbent and a catalyst. A chromatographic column is packed with a selected catalyst, AMBERLITE™ IRA904, and both reaction and chromatographic elution are studied at different temperatures and feed concentrations. The resulting chromatograms are fitted to a mathematical model to obtain adsorption equilibrium and reaction kinetic parameters by the inverse method. Compared to esterification investigated in a previous study, transesterification has advantages such as a higher conversion at lower temperature and easy removal of the byproduct which may lead to higher productivity. Deactivation of anion exchange resins is observed and potential solutions are suggested.

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

    Indian Academy of Sciences (India)

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

    2011-03-01

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

  11. Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

    KAUST Repository

    Geise, Geoffrey M.

    2013-10-23

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

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

    Science.gov (United States)

    Yoshimura, Tomokazu; Akiba, Kazuki

    2016-01-01

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

  13. Anion binding by protonated forms of the tripodal ligand tren.

    Science.gov (United States)

    Bazzicalupi, Carla; Bencini, Andrea; Bianchi, Antonio; Danesi, Andrea; Giorgi, Claudia; Valtancoli, Barbara

    2009-03-16

    The interaction of the protonated forms of tris(2-aminoethyl)amine (tren) with NO(3)(-), SO(4)(2-), TsO(-), PO(4)(3-), P(2)O(7)(4-), and P(3)O(10)(5-) was studied by means of potentiometric and microcalorimetric measurements in a 0.10 M NMe(4)Cl aqueous solution at 298.1 +/- 0.1 K, affording stability constants and the relevant energetic terms DeltaH degrees and TDeltaS degrees of complexation. Thermodynamic data show that these anion complexation processes are mainly controlled by electrostatic forces, although hydrogen-bond interactions and solvation effects also contribute to complex stability, leading, in some cases, to special DeltaH degrees and TDeltaS degrees contributions. The crystal structures of [H(3)L][NO(3)](3) and [H(3)L][TsO](3) evidence a preferred tridentate coordination mode of the triprotonated ligands in the solid state. Accordingly, the H(3)L(3+) receptor binds a single oxygen atom of both NO(3)(-) and TsO(-) by means of its three protonated fingers, although in the crystal structure of [H(3)L][TsO](3), one conformer displaying bidentate coordination was also found. Modeling studies performed on the [H(3)L(NO(3))](2+) complex suggested that the tridentate binding mode is the preferred one in aqueous solution, while in the gas phase, a different complex conformation in which the receptor interacts with all three oxygen atoms of NO(3)(-) is more stable.

  14. Ionic resistance and permselectivity tradeoffs in anion exchange membranes.

    Science.gov (United States)

    Geise, Geoffrey M; Hickner, Michael A; Logan, Bruce E

    2013-10-23

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

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

    Science.gov (United States)

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

    2000-01-01

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

  16. Analysis of anions in ambient aerosols by microchip capillary electrophoresis.

    Science.gov (United States)

    Liu, Yan; MacDonald, David A; Yu, Xiao-Ying; Hering, Susanne V; Collett, Jeffrey L; Henry, Charles S

    2006-11-01

    We describe a microchip capillary electrophoresis method for the analysis of nitrate and sulfate in ambient aerosols. Investigating the chemical composition of ambient aerosol particles is essential for understanding their sources and effects. Significant progress has been made towards developing mass spectrometry-based instrumentation for rapid qualitative analysis of aerosols. Alternative methods for rapid quantification of selected high abundance compounds are needed to augment the capacity for widespread routine analysis. Such methods could provide much higher temporal and spatial resolution than can be achieved currently. Inorganic anions comprise a large percentage of particulate mass, with nitrate and sulfate among the most abundant species. While ion chromatography has proven very useful for analyzing extracts of time-integrated ambient aerosol samples collected on filters and for semi-continuous, on-line particle composition measurements, there is a growing need for development of new compact, inexpensive approaches to routine on-line aerosol ion analysis for deployment in spatially dense, atmospheric measurement networks. Microchip capillary electrophoresis provides the necessary speed and portability to address this need. In this report, on-column contact conductivity detection is used with hydrodynamic injection to create a simple microchip instrument for analysis of nitrate and sulfate. On-column contact conductivity detection was achieved using a Pd decoupler placed upstream from the working electrodes. Microchips containing two Au or Pd working electrodes showed a good linear range (5-500 microM) and low limits-of-detection for sulfate and nitrate, with Au providing the lowest detection limits (1 microM) for both ions. The completed microchip system was used to analyze ambient aerosol filter samples. Nitrate and sulfate concentrations measured by the microchip matched the concentrations measured by ion chromatography.

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2006-11-21

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

  19. The effect of anions on the human P2X7 receptor.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2014-07-21

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

  1. Interactions between Hofmeister anions and the binding pocket of a protein.

    Science.gov (United States)

    Fox, Jerome M; Kang, Kyungtae; Sherman, Woody; Héroux, Annie; Sastry, G Madhavi; Baghbanzadeh, Mostafa; Lockett, Matthew R; Whitesides, George M

    2015-03-25

    This paper uses the binding pocket of human carbonic anhydrase II (HCAII, EC 4.2.1.1) as a tool to examine the properties of Hofmeister anions that determine (i) where, and how strongly, they associate with concavities on the surfaces of proteins and (ii) how, upon binding, they alter the structure of water within those concavities. Results from X-ray crystallography and isothermal titration calorimetry show that most anions associate with the binding pocket of HCAII by forming inner-sphere ion pairs with the Zn(2+) cofactor. In these ion pairs, the free energy of anion-Zn(2+) association is inversely proportional to the free energetic cost of anion dehydration; this relationship is consistent with the mechanism of ion pair formation suggested by the "law of matching water affinities". Iodide and bromide anions also associate with a hydrophobic declivity in the wall of the binding pocket. Molecular dynamics simulations suggest that anions, upon associating with Zn(2+), trigger rearrangements of water that extend up to 8 Å away from their surfaces. These findings expand the range of interactions previously thought to occur between ions and proteins by suggesting that (i) weakly hydrated anions can bind complementarily shaped hydrophobic declivities, and that (ii) ion-induced rearrangements of water within protein concavities can (in contrast with similar rearrangements in bulk water) extend well beyond the first hydration shells of the ions that trigger them. This study paints a picture of Hofmeister anions as a set of structurally varied ligands that differ in size, shape, and affinity for water and, thus, in their ability to bind to—and to alter the charge and hydration structure of—polar, nonpolar, and topographically complex concavities on the surfaces of proteins.

  2. Tunable separation of anions and cations by column switching in ion chromatography.

    Science.gov (United States)

    Amin, Muhammad; Lim, Lee Wah; Takeuchi, Toyohide

    2007-03-15

    A convenient ion chromatography method has been proposed for the routine and simple determination of anions (Cl(-), SO(4)(2-) and NO(3)(-)) and/or cations (Na(+), NH(4)(+), K(+), Mg(2+) and Ca(2+)) using a single pump, a single eluent and a single detector. The present system used cation-exchange and anion-exchange columns connected in series via two 6-port switching valves or a single 10-port valve. The connection order of the ion-exchange columns could be varied by switching the valve(s). The present system therefore allowed the separation of either cations or anions in a single chromatographic run. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When 2.4mM 5-sulfosalicylic acid was used as the eluent, the three anions and the five cations could be separated on the anion-exchange column and cation-exchange column, respectively. In order to obtain the separations of the target ions, the injection valve was placed between the two columns. Complete separations of the above anions or cations were demonstrated within 10min each. The detection limits at S/N=3 were 19-50ppb (mug/l) for cations and 10-14ppb for anions. The relative standard deviations of the analyte ions were less than 1.1, 2.9 and 2.8% for retention time, peak area and peak height, respectively. This proposed technique was applied to the determination of common anions and cations in river water samples.

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

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

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

  4. Segregation of anion (Cl−) impurities at transparent polycrystalline α-alumina interfaces

    OpenAIRE

    Tewari, Abhishek; Nabiei, Farhang; Cantoni, Marco; Bowen, Paul; Hébert, Cécile

    2014-01-01

    Small amounts of anion impurities (e.g. Cl), which are incorporated during the synthesis of ceramic powders, can affect the properties and microstructure of the final sintered ceramic. The effect of anion impurities is a little studied and poorly understood phenomenon. In this work a combination of STEM-EDX analysis and atomistic modeling approach was used to understand the segregation of Cl in transparent alumina ceramics. A high resolution analytical electron microscopy study showed the pre...

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

    Science.gov (United States)

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

    2014-10-22

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

  6. Chemiluminescence Imaging of Superoxide Anion Detects Beta-Cell Function and Mass.

    Science.gov (United States)

    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.

  7. Dissecting the effect of anions on Hg2+ detection using a FRET based DNA probe.

    Science.gov (United States)

    Kiy, Mehmet Murat; Zaki, Ahmed; Menhaj, Arsalsan Beg; Samadi, Azadeh; Liu, Juewen

    2012-08-07

    Many biosensors have been developed to detect Hg(2+) using thymine-rich DNA. While sensor response to various cations is often studied to demonstrate selectivity, the effect of anions has been largely overlooked. Anions may compete with DNA for metal binding and thus produce a false negative result. Anions cannot be added alone; the cation part of a salt may cause DNA compaction and other effects, obscuring the role of anions. We find that the sensitivity of a FRET-based Hg(2+) probe is independent of Na(+) concentration. Therefore, by using various sodium salts, any change in sensitivity can be attributed solely to the effect of anions. Halide salts, sulfides, and amines are strong inhibitors; anions containing oxo or hydroxyl groups (e.g. nitrate, sulfate, phosphate, carbonate, acetate, and citrate) do not interfere with Hg(2+) detection even at 100 mM concentration. Mercury hydrolysis and its diffusion into polypropylene containers can also strongly affect the detection results. We conclude that thymine-rich DNA should be useful for Hg(2+) detection in many environmental water samples.

  8. Fluorescence anion sensors based on combination of conformational restriction and photo-induced electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ge, E-mail: liu_ge2008@163.com [Department of Chemistry, Chifeng University, Chifeng, 024000 (China); Shao, Jie, E-mail: njshao@live.cn [College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu 215123 (China)

    2013-03-15

    Six fluorescence and colorimetric sensors (1-6) were designed and synthesized through a facile method. These compounds, whose structures were characterized by {sup 1}H NMR, elemental analyses and MS, could be easily prepared by simple synthesis method. In these sensor molecules, azo group and conjugated di-benzene unit acted as a chromophore and a fluorophore; respectively, and phenol moieties are anion binding sites. In dry DMSO solution, significant red shifts in UV-vis spectra with visible color changes were observed when the sensors were exposed to anions with strong base. Particularly, the simple compounds gave interesting fluorescence changes upon presence of anions, which probably resulted from electronic effects of the substituent. The sensors (1-3) with the nitro group exhibited 'turn-on' fluorescence responses to anions due to conformational restriction and 4-6 with absence of -NO{sub 2} group showed 'turn-off' fluorescence responses to anion owing to photo-induced electron transfer. - Highlights: Black-Right-Pointing-Pointer Six fluorescence and colorimetric anion sensors based on azo derivatives were showed. Black-Right-Pointing-Pointer Azo group and di-benzene unit acted as a chromophore and a fluorophore respectively. Black-Right-Pointing-Pointer Combination of conformational restriction and PET was exploited as fluorescence mechanism.

  9. Nonionic surfactant enhanced semipermanent coatings for capillary electrophoresis of inorganic anions without use of organic additives.

    Science.gov (United States)

    Yao, Lihua; Liu, Qian; Li, Yi; Yao, Shouzhuo

    2011-09-01

    Separation of inorganic anions by capillary electrophoresis (CE) is usually conducted in co-electroosmotic mode due to the large electrophoretic mobilities of inorganic anions. Semipermanent surfactant coatings have been shown to be effective for CE of inorganic anions due to their strong capability of electroosmotic flow (EOF) manipulation. However, semipermanent coatings often suffer from their unsatisfactory stability. In addition, organic solvent additives are usually required to adjust the selectivity, which also aggravate the degradation of coating. In this work, a novel semipermanent coating consisting of cationic Gemini surfactant 18-10-18 and nonionic surfactant Tween 20 was developed to separate inorganic anions in CE. This coating is easy to prepare and more stable than pure Gemini coating. The introduction of nonionic surfactant in the coating not only suppresses the reversed EOF but can also adjust the selectivity of separation. Good separations of six model anions were achieved, the separation efficiency was as high as 65040-169700 plates/m and the RSDs of the migration times were less than 0.5 and 2.5% for run-to-run and day-to-day assays, respectively. Calibration curves were linear in the range of 0.05-5.0 mM; the detection limits ranged from 20 to 50 μM. More importantly, no organic solvents are required in the background buffer to achieve the satisfactory separations. This guarantees the coating stability and makes the method greener than most of other methods for CE of inorganic anions.

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

    KAUST Repository

    Savizi, Iman Shahidi Pour

    2011-04-01

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

  11. DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C. (Northwestern)

    2010-01-18

    DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the release of DNA from lipid surfaces induced by anionic liposomes. The separation of DNA from lipid measured this way was considerably slower and less complete than that estimated with noncovalently labeled DNA, and depends on the lipid composition of both lipoplexes and anionic liposomes. This result was confirmed by centrifugal separation of released DNA and lipid. X-ray diffraction revealed a clear correlation of the DNA release capacity of the anionic lipids with the interfacial curvature of the mesomorphic structures developed when the anionic and cationic liposomes were mixed. DNA release also correlated with the rate of fusion of anionic liposomes with lipoplexes. It is concluded that the tendency to fuse and the phase preference of the mixed lipid membranes are key factors for the rate and extent of DNA release. The approach presented emphasizes the importance of the lipid composition of both lipoplexes and target membranes and suggests optimal transfection may be obtained by tailoring lipoplex composition to the lipid composition of target cells.

  12. Interaction of inorganic anions with iron-mineral adsorbents in aqueous media--a review.

    Science.gov (United States)

    Kumar, Eva; Bhatnagar, Amit; Hogland, William; Marques, Marcia; Sillanpää, Mika

    2014-01-01

    A number of inorganic anions (e.g., nitrate, fluoride, bromate, phosphate, and perchlorate) have been reported in alarming concentrations in numerous drinking water sources around the world. Their presence even in very low concentrations may cause serious environmental and health related problems. Due to the presence and significance of iron minerals in the natural aquatic environment and increasing application of iron in water treatment, the knowledge of the structure of iron and iron minerals and their interactions with aquatic pollutants, especially inorganic anions in water are of great importance. Iron minerals have been known since long as potential adsorbents for the removal of inorganic anions from aqueous phase. The chemistry of iron and iron minerals reactions in water is complex. The adsorption ability of iron and iron minerals towards inorganic anions is influenced by several factors such as, surface characteristics of the adsorbent (surface area, density, pore volume, porosity, pore size distribution, pHpzc, purity), pH of the solution, and ionic strength. Furthermore, the physico-chemical properties of inorganic anions (pore size, ionic radius, bulk diffusion coefficient) also significantly influence the adsorption process. The aim of this paper is to provide an overview of the properties of iron and iron minerals and their reactivity with some important inorganic anionic contaminants present in water. It also summarizes the usage of iron and iron minerals in water treatment technology.

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Science.gov (United States)

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

    2016-07-14

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

  15. Potentiometric response and mechanism of anionic recognition of heterocalixarene-based ion selective electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Shishkanova, T.V. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)]. E-mail: tatiana.shishkanova@vscht.cz; Sykora, D. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Sessler, J.L. [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712-0615 (United States); Kral, V. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2007-03-28

    The ion selective electrode (ISE)-based potentiometric approach is shown to be an effective means of characterizing the anion recognition sites in the molecular receptor calix[2]pyridino[2]pyrrole (CPP). In particular, potentiometric pH-measurements involving the use of experimental PVC-membranes based on CPP revealed the existence of both mono- and diprotonated forms of the receptor under readily accessible conditions. Based on these analyses, apparent surface protonation constants for this heterocalixarene were found to lie between 8.5-8.9 (pK {sub B1}) and 3.3-3.8 (pK {sub B2}). CPP was found to interact with targeted anionic analytes based on both coulombic and hydrogen bond interactions, as inferred from varying the kinds of ionic sites present within the membrane phase. Potentiometric selectivity studies revealed that CPP preferred 'Y-shaped' anions (e.g. acetate, lactate, benzoate) over spherical anions (e.g. fluoride and chloride), fluoride over chloride within the set of spherical anions, and the ortho-isomer over the corresponding meta- and para-isomers in the case of hydroxybenzoate (salicylate and congeners). In the context of this study, the advantages of potentiometric determinations of acetylsalicylic acid using optimized PVC-membranes based on CPP relative to more conventional PVC-membrane ISEs based on traditional anion exchanger were also demonstrated.

  16. Adsorption of Ce(Ⅳ) Anionic Nitrato Complexes onto Anion Exchangers and Its Application for Ce(Ⅳ) Separation from Rare Earths(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ce(Ⅳ) nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine (PVP) and quaternized PVP incorporated into porous silica matrix. The effect of nitric acid concentration (0.5~6 mol·L-1) and temperature (278~318 K) on Ce(Ⅳ) sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce(NO3)6]2- complex is the main adsorbed Ce(Ⅳ) species. Oxidation of sorbents by adsorbed Ce(Ⅳ) species resulting in Ce(Ⅲ) release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce(Ⅳ) reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce(Ⅳ) from La(Ⅲ) and Y(Ⅲ) was carried out from 6 mol·L-1 nitric acid with PVP based anion exchanger. Reasonable Ce(Ⅳ) breakthrough capacity (0.7 mol·kg-1 PVP) was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce(Ⅲ) leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L-1 nitric acid was successful (recovery 100%±4%) and Ce solution of high purity (>99.97%) with respect to La and Y content was gained.

  17. Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice.

    Science.gov (United States)

    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.

  18. Cytosolic nucleotides block and regulate the Arabidopsis vacuolar anion channel AtALMT9.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2003-01-01

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

  20. Absorption of the selenite anion from aqueous solutions by thermally activated layered double hydroxide.

    Science.gov (United States)

    Liu, Rui; Frost, Ray L; Martens, Wayde N

    2009-03-01

    The presence of selenite or selenate in potable water is a health hazard especially when consumed over a long period of time. Its removal from potable water is of importance. This paper reports technology for the removal of selenite from water through the use of thermally activated layered double hydroxides. Mg/Al hydrotalcites with selenite in the interlayer were prepared at different times from 0.5 to 20 h through ion exchange. X-ray diffraction of the MgAlSeO3 hydrotalcites indicates that the selenite anion entered the interlayer spacing of Mg/Al hydrotalcite and MgAlSeO3 hydrotalcite was formed. Raman spectra proved the presence of selenite anion in the hydrotalcite interlayer as the counter anion. The band intensity and width of MgAlSeO3 hydrotalcite in the region of 3800-3000 cm(-1) increase with the adsorption of selenite by the Mg/Al hydrotalcite. The characteristic bands of free selenite anions in the MgAlSeO3 hydrotalcites are located between the region between 850 and 800 cm(-1). The Raman spectra of the lower wave number region of 550-500 cm(-1) show a shift toward higher wave numbers with adsorption of the selenite. An estimation of the amount of selenite anion removed by the thermally activated layered double hydroxide was obtained through the measurement of the intensity of the selenite Raman bands at 814 and 835 cm(-1) resulting from the amount of selenite anion remaining in solution. Thermally activated LDHs provide a mechanism for removing selenite anions from aqueous solutions.