Sample records for cations monovalent

  1. Incorporation of Monovalent Cations in Sulfate Green Rust

    Christiansen, B. C.; Dideriksen, K.; Katz, A.;


    Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both...

  2. Circular Dichroism is Sensitive to Monovalent Cation Binding in Monensin Complexes.

    Nedzhib, Ahmed; Kessler, Jiří; Bouř, Petr; Gyurcsik, Béla; Pantcheva, Ivayla


    Monensin is a natural antibiotic that exhibits high affinity to certain metal ions. In order to explore its potential in coordination chemistry, circular dichroism (CD) spectra of monensic acid A (MonH) and its derivatives containing monovalent cations (Li(+) , Na(+) , K(+) , Rb(+) , Ag(+) , and Et4 N(+) ) in methanolic solutions were measured and compared to computational models. Whereas the conventional CD spectroscopy allowed recording of the transitions down to 192 nm, synchrotron radiation circular dichroism (SRCD) revealed other bands in the 178-192 nm wavelength range. CD signs and intensities significantly varied in the studied compounds, in spite of their similar crystal structure. Computational modeling based on the Density Functional Theory (DFT) and continuum solvent model suggests that the solid state monensin structure is largely conserved in the solutions as well. Time-dependent Density Functional Theory (TDDFT) simulations did not allow band-to-band comparison with experimental spectra due to their limited precision, but indicated that the spectral changes were caused by a combination of minor conformational changes upon the monovalent cation binding and a direct involvement of the metal electrons in monensin electronic transitions. Both the experiment and simulations thus show that the CD spectra of monensin complexes are very sensitive to the captured ions and can be used for their discrimination. Chirality 28:420-428, 2016. © 2016 Wiley Periodicals, Inc. PMID:27062535

  3. Diphtheria toxin-induced channels in Vero cells selective for monovalent cations

    Sandvig, K.; Olsnes, S.


    Ion fluxes associated with translocation of diphtheria toxin across the surface membrane of Vero cells were studied. When cells with surface-bound toxin were exposed to low pH to induce toxin entry, the cells became permeable to Na+, K+, H+, choline+, and glucosamine+. There was no increased permeability to Cl-, SO4(-2), glucose, or sucrose, whereas the uptake of /sup 45/Ca2+ was slightly increased. The influx of Ca2+, which appears to be different from that of monovalent cations, was reduced by several inhibitors of anion transport and by verapamil, Mn2+, Co2+, and Ca2+, but not by Mg2+. The toxin-induced fluxes of N+, K+, and protons were inhibited by Cd2+. Cd2+ also protected the cells against intoxication by diphtheria toxin, suggesting that the open cation-selective channel is required for toxin translocation. The involvement of the toxin receptor is discussed.

  4. Structure And Gene Silencing Activities of Monovalent And Pentavalent Cationic Lipid Vectors Complexed With Sirna

    Bouxsein, N.F.; McAllister, C.S.; Ewert, K.K.; Samuel, C.E.; Safinya, C.R.; /UC, Santa Barbara


    Small interfering RNAs (siRNAs) of 19-25 bp mediate the cleavage of complementary mRNA, leading to post-transcriptional gene silencing. We examined cationic lipid (CL)-mediated delivery of siRNA into mammalian cells and made comparisons to CL-based DNA delivery. The effect of lipid composition and headgroup charge on the biophysical and biological properties of CL-siRNA vectors was determined. X-ray diffraction revealed that CL-siRNA complexes exhibited lamellar and inverted hexagonal phases, qualitatively similar to CL-DNA complexes, but also formed other nonlamellar structures. Surprisingly, optimally formulated inverted hexagonal 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) CL-siRNA complexes exhibited high toxicity and much lower target-specific gene silencing than lamellar CL-siRNA complexes even though optimally formulated, inverted hexagonal CL-DNA complexes show high transfection efficiency in cell culture. We further found that efficient silencing required cationic lipid/nucleic acid molar charge ratios (chg) nearly an order of magnitude larger than those yielding efficiently transfecting CL-DNA complexes. This second unexpected finding has implications for cell toxicity. Multivalent lipids (MVLs) require a smaller number of cationic lipids at a given chg of the complex. Consistent with this observation, the pentavalent lipid MVL5 exhibited lower toxicity and superior silencing efficiency over a large range in both the lipid composition and chg when compared to monovalent DOTAP. Most importantly, MVL5 achieved much higher total knockdown of the target gene in CL-siRNA complex regimes where toxicity was low. This property of CL-siRNA complexes contrasts to CL-DNA complexes, where the optimized transfection efficiencies of multivalent and monovalent lipids are comparable.

  5. The interaction of monovalent cations with the sodium pump of low-potassium goat erythrocytes.

    Cavieres, J D; Ellory, J C


    activity against the concentration of K and its congeners, show the sequence Tl > K > Rb > Na > Cs for the affinities at the internal cation sites of the LK sodium pump. Anti-L treatment decreases the relative magnitude of Na and Cs selectivities, it being not certain whether a Rb-Na transition then occurs.7. The results are discussed in terms of possible mechanisms whereby the sodium pump of LK and HK red cells may adjust the properties of their cation sites upon translocation of monovalent cations. PMID:144181

  6. A dimeric DNA interface stabilized by stacked A.(G.G.G.G).A hexads and coordinated monovalent cations.

    Kettani, A; Gorin, A; Majumdar, A; Hermann, T; Skripkin, E; Zhao, H; Jones, R; Patel, D J


    We report on the identification of an A.(G.G.G.G).A hexad pairing alignment which involves recognition of the exposed minor groove of opposing guanines within a G.G.G.G tetrad through sheared G.A mismatch formation. This unexpected hexad pairing alignment was identified for the d(G-G-A-G-G-A-G) sequence in 150 mM Na(+) (or K(+)) cation solution where four symmetry-related strands align into a novel dimeric motif. Each symmetric half of the dimeric "hexad" motif is composed of two strands and contains a stacked array of an A.(G.G.G.G).A hexad, a G.G.G.G tetrad, and an A.A mismatch. Each strand in the hexad motif contains two successive turns, that together define an S-shaped double chain reversal fold, which connects the two G-G steps aligned parallel to each other along adjacent edges of the quadruplex. Our studies also establish a novel structural transition for the d(G-G-A-G-G-A-N) sequence, N=T and G, from an "arrowhead" motif stabilized through cross-strand stacking and mismatch formation in 10 mM Na(+) solution (reported previously), to a dimeric hexad motif stabilized by extensive inter-subunit stacking of symmetry-related A.(G.G.G.G).A hexads in 150 mM Na(+) solution. Potential monovalent cation binding sites within the arrowhead and hexad motifs have been probed by a combination of Brownian dynamics and unconstrained molecular dynamics calculations. We could not identify stable monovalent cation-binding sites in the low salt arrowhead motif. By contrast, five electronegative pockets were identified in the moderate salt dimeric hexad motif. Three of these are involved in cation binding sites sandwiched between G.G.G. G tetrad planes and two others, are involved in water-mediated cation binding sites spanning the unoccupied grooves associated with the adjacent stacked A.(G.G.G.G).A hexads. Our demonstration of A.(G. G.G.G).A hexad formation opens opportunities for the design of adenine-rich G-quadruplex-interacting oligomers that could potentially target base

  7. Competitive separation of di- vs. mono-valent cations in electrodialysis: effects of the boundary layer properties.

    Kim, Younggy; Walker, W Shane; Lawler, Desmond F


    In electrodialysis desalination, the boundary layer near ion-exchange membranes is the limiting region for the overall rate of ionic separation due to concentration polarization over tens of micrometers in that layer. Under high current conditions, this sharp concentration gradient, creating substantial ionic diffusion, can drive a preferential separation for certain ions depending on their concentration and diffusivity in the solution. Thus, this study tested a hypothesis that the boundary layer affects the competitive transport between di- and mono-valent cations, which is known to be governed primarily by the partitioning with cation-exchange membranes. A laboratory-scale electrodialyzer was operated at steady state with a mixture of 10mM KCl and 10mM CaCl(2) at various flow rates. Increased flows increased the relative calcium transport. A two-dimensional model was built with analytical solutions of the Nernst-Planck equation. In the model, the boundary layer thickness was considered as a random variable defined with three statistical parameters: mean, standard deviation, and correlation coefficient between the thicknesses of the two boundary layers facing across a spacer. Model simulations with the Monte Carlo method found that a greater calcium separation was achieved with a smaller mean, greater standard deviation, or more negative correlation coefficient. The model and experimental results were compared for the cationic transport number as well as the current and potential relationship. The mean boundary layer thickness was found to decrease from 40 to less than 10 μm as the superficial water velocity increased from 1.06 to 4.24 cm/s. The standard deviation was greater than the mean thickness at slower water velocities and smaller at faster water velocities. PMID:22336628

  8. Systems Biology of Monovalent Cation Homeostasis in Yeast: The Translucent Contribution

    Ariňo, J.; Aydar, E.; Drulhe, S.; Ganser, D.; Jorrín, J.; Kahm, M.; Krause, F.; Petrezsélyová, Silvia; Yenush, L.; Zimmermannová, Olga; Van Heusden, G.P.H.; Kschischo, M.; Ludwig, J.; Palmer, Ch.; Ramos, J.; Sychrová, Hana


    Roč. 64, č. 2014 (2014), s. 1-63. ISSN 0065-2911 R&D Projects: GA ČR(CZ) GAP503/10/0307; GA AV ČR(CZ) IAA500110801; GA MŠk(CZ) LD13037 Institutional support: RVO:67985823 Keywords : yeast * cation homeostasis * osmotolerance Subject RIV: EE - Microbiology, Virology Impact factor: 3.250, year: 2014

  9. Increased mineral oil bioavailability in slurries by monovalent cation-induced dispersion

    Bioavailability of apolar contaminants is an important limiting factor for microbial reclamation of polluted soils. This paper describes a laboratory study of the relation between microaggregate stability and bioavailability of mineral oil in soil-water slurries. The stability of microaggregates in slurries is regulated by the valence and surface affinity of the cations in the system, and by the complexing anion P2O74- (metaphosphate). A silt loam, contaminated with a weathered gas oil, was collected from an oil refinery site. Degradation rates were monitored in small-scale incubations at solid:liquid ratios of 1:5 (w/w). The solution contained Ca, Na, or K as the dominant cation. The levels of nutrients and metaphosphate were varied. Biodegradation rates increased with the sequence Ca 2 treatment. Measurements of the particle size distribution the slurry showed that an increase in the finer fractions qualitatively correlated with enhanced biodegradation. This is a strong indication that dispersion of the microaggregates increased bioavailability of the contaminant

  10. Conserved and Diversified Gene Families of Monovalent Cation/H+ Antiporters from Algae to Flowering Plants

    Salil eChanroj


    Full Text Available All organisms have evolved strategies to regulate ion and pH homeostasis in response to developmental and environmental cues. One strategy is mediated by cation-proton antiporters (CPA. CPA1 genes found in bacteria, fungi, metazoa and plants have been functionally-characterized; though roles of plant CPA2 genes in KEA (K+-efflux antiporter and CHX (cation/H+ exchanger families are largely unknown. Phylogenetic analysis showed that three clades of the Na+-H+ exchanger (NHX family have been conserved from single-celled alga to Arabidopsis. These are i plasma membrane-bound SOS1/AtNHX7 that share ancestry with prokaryote NhaP, ii endosomal AtNHX5/6 that is part of the eukaryote Intracellular-NHE clade, and iii a vacuolar NHX clade (AtNHX1-4 specific to plants. Early diversification of KEA genes possibly from ancestral genes of a cyanobacterium is suggested for three K+-efflux antiporter clades (KEA/Kef seen in all plants. Intriguingly, the CHX gene family blossomed from a few members in early land plants to >40 genes in legumes. Homologs from spirogyra or moss share high similarity with guard cell-specific AtCHX20, suggesting that AtCHX20 and its relatives (AtCHX16-19 are founders of the family. Evolutionary analysis suggests pollen-expressed CHX genes appeared later in monocots and early eudicots. AtCHX proteins have been localized to intracellular and plasma membrane of plants, and shown to mediate K+ transport and pH homeostasis. Thus KEA genes are conserved from green algae to angiosperms, and their presence in red algae and secondary endosymbionts suggest a role in plastids. In contrast, AtNHX1-4 subtype evolved in ancestral plants to handle ion homeostasis of vacuoles in all cell types. The strong presence of CHX genes in land plants, but not in metazoa or fungi, would infer a role of ion and pH homeostasis at dynamic endomembranes to support vegetative and reproductive success of flowering plants.

  11. Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography.

    Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim


    A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na(+)), potassium (K(+)), ammonium (NH4 (+)), chloride (Cl(-)) and nitrate (NO3 (-)) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples. PMID:26786906

  12. Characterization of Halomonas sp. strain H11 α-glucosidase activated by monovalent cations and its application for efficient synthesis of α-D-glucosylglycerol.

    Ojima, Teruyo; Saburi, Wataru; Yamamoto, Takeshi; Kudo, Toshiaki


    An α-glucosidase (HaG) with the following unique properties was isolated from Halomonas sp. strain H11: (i) high transglucosylation activity, (ii) activation by monovalent cations, and (iii) very narrow substrate specificity. The molecular mass of the purified HaG was estimated to be 58 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). HaG showed high hydrolytic activities toward maltose, sucrose, and p-nitrophenyl α-D-glucoside (pNPG) but to almost no other disaccharides or malto-oligosaccharides higher than trisaccharides. HaG showed optimum activity to maltose at 30°C and pH 6.5. Monovalent cations such as K(+), Rb(+), Cs(+), and NH(4)(+) increased the enzymatic activity to 2- to 9-fold of the original activity. These ions shifted the activity-pH profile to the alkaline side. The optimum temperature rose to 40°C in the presence of 10 mM NH(4)(+), although temperature stability was not affected. The apparent K(m) and k(cat) values for maltose and pNPG were significantly improved by monovalent cations. Surprisingly, k(cat)/K(m) for pNPG increased 372- to 969-fold in their presence. HaG used some alcohols as acceptor substrates in transglucosylation and was useful for efficient synthesis of α-d-glucosylglycerol. The efficiency of the production level was superior to that of the previously reported enzyme Aspergillus niger α-glucosidase in terms of small amounts of by-products. Sequence analysis of HaG revealed that it was classified in glycoside hydrolase family 13. Its amino acid sequence showed high identities, 60%, 58%, 57%, and 56%, to Xanthomonas campestris WU-9701 α-glucosidase, Xanthomonas campestris pv. raphani 756C oligo-1,6-glucosidase, Pseudomonas stutzeri DSM 4166 oligo-1,6-glucosidase, and Agrobacterium tumefaciens F2 α-glucosidase, respectively. PMID:22226947

  13. Experimental Characterization and Modelization of Ion Exchange Kinetics for a Carboxylic Resin in Infinite Solution Volume Conditions. Application to Monovalent-Trivalent Cations Exchange

    This study is devoted to the characterization of ion exchange inside a microsphere of carboxylic resin. It aims at describing the kinetics of this exchange reaction which is known to be controlled by interdiffusion in the particle. The fractional attainment of equilibrium function of time depends on the concentration of the cations in the resin which can be modelled by the Nernst-Planck equation. A powerful approach for the numerical resolution of this equation is introduced in this paper. This modeling is based on the work of Helfferich but involves an implicit numerical scheme which reduces the computational cost. Knowing the diffusion coefficients of the cations in the resin and the radius of the spherical exchanger, the kinetics can be hence completely determined. When those diffusion parameters are missing, they can be deduced by fitting experimental data of fractional attainment of equilibrium. An efficient optimization tool coupled with the implicit resolution has been developed for this purpose. A monovalent/trivalent cation exchange had been experimentally characterized for a carboxylic resin. Diffusion coefficients and concentration profiles in the resin were then deduced through this new model. (authors)

  14. Optimization of Adsorption of Hydrophobic Herbicides on Montmorillonite Preadsorbed by Monovalent Organic Cations: Interaction between Phenyl Rings

    Undabeytia López, Tomás; Yaron Marcovich, D.; El-Nahhala, Yasser; Polubesova, T.; Serban, T.; Rytwo, Giora; Lagaly, G.; Rubin, Baruch; Nir, Shlomo


    This study aimed to optimize organo-clay formulations for reduction of leaching of the herbicides alachlor, metolachlor, and norflurazon, which include a phenyl ring in the structure. The adsorbed amounts of herbicides increased severalfold when montmorillonite was preadsorbed by an organic cation; benzyltrimethylammonium (BTMA) was more effective than benzyltriethylammonium (BTEA). Fourier transform infrared studies indicated interactions between alachlor molecules and adsorbed BTMA. The ads...

  15. Differential effect of HOE642 on two separate monovalent cation transporters in the human red cell membrane

    Bernhardt, Ingolf; Weiss, Erwin; Robinson, Hannah C; Wilkins, Robert; Bennekou, Poul


    determinations showed that HOE642 exerted differential effects on the NSVDC channel and the K(+)(Na(+))/H(+) exchanger, confirming that the salt loss observed in low ionic strength solutions represents contributions from at least two independent ion transport pathways. The findings are discussed in the context......Residual K(+) fluxes in red blood cells can be stimulated in conditions of low ionic strength. Previous studies have identified both the non-selective, voltage-dependent cation (NSVDC) channel and the K(+)(Na(+))/H(+) exchanger as candidate pathways mediating this effect, although it is possible...... that these pathways represent different modes of operation of a single system. In the present study the effects of HOE642, recently characterised as an inhibitor of the K(+)(Na(+))/H(+) exchanger, on NSVDC has been determined to clarify this question. Radioisotope flux measurements and conductance...

  16. Influence of monovalent alkaline metal cations on binder-free nano-zeolite X in para-xylene separation

    Milad Rasouli; Nakisa Yaghobi; Hossein Atashi; Majid Rasouli


    The adsorption process was studied for separating para-xylene from xylene mixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO2/Al2O3 was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C8 aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C8 aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylben-zene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

  17. Stable isotope (C, O) and monovalent cation fractionation upon synthesis of carbonate-bearing hydroxyl apatite (CHAP) via calcite transformation

    Böttcher, Michael E.; Schmiedinger, Iris; Wacker, Ulrike; Conrad, Anika C.; Grathoff, Georg; Schmidt, Burkhard; Bahlo, Rainer; Gehlken, Peer-L.; Fiebig, Jens


    Carbonate-bearing hydroxyl-apatite (CHAP) is of fundamental and applied interest to the (bio)geochemical, paleontological, medical and material science communities, since it forms the basic mineral phase in human and animal teeth and bones. In addition, it is found in non-biogenic phosphate deposits. The stable isotope and foreign element composition of biogenic CHAP is widely used to estimate the formation conditions. This requires careful experimental calibration under well-defined boundary conditions. Within the DFG project EXCALIBOR, synthesis of carbonate-bearing hydroxyapatite was conducted via the transformation of synthetic calcite powder in aqueous solution as a function of time, pH, and temperature using batch-type experiments. The aqueous solution was analyzed for the carbon isotope composition of dissolved inorganic carbonate (gas irmMS), the oxygen isotope composition of water (LCRDS), and the cationic composition. The solid was characterized by powder X-ray diffraction, micro Raman and FTIR spectroscopy, SEM-EDX, elemental analysis (EA, ICP-OES) and gas irmMS. Temperature was found to significantly impact the transformation rate of calcite to CHAP. Upon complete transformation, CHAP was found to contain up to 5% dwt carbonate, depending on the solution composition (e.g., pH), both incorporated on the A and B type position of the crystal lattice. The oxygen isotope fractionation between water and CHAP decreased with increasing temperature with a tentative slope shallower than those reported in the literature for apatite, calcite or aragonite. In addition, the presence of dissolved NH4+, K+ or Na+ in aqueous solution led to partial incorporation into the CHAP lattice. How these distortions of the crystal lattice may impact stable isotope discrimination is subject of future investigations.

  18. The ATPase activity of saponin-treated rat erythrocytes: regulation by monovalent cations, calcium, ouabain, and furosemide.

    Petrunyaka, V V; Panyushkina, E A; Severina, E P; Orlov, S N


    The ATPase activities were studied in rat erythrocytes permeabilized with saponin. The concentrations of calcium and magnesium ions were varied within the range of 0.1-60 microM and 50-370 microM, respectively, by using EGTA-citrate buffer. The maximal activity of Ca2(+)-ATPase of permeabilized erythrocytes was by one order of magnitude higher, whereas the Ca2(+)-binding affinity was 1.5-2 times higher than that in erythrocyte ghosts washed an isotonic solution containing EGTA. Addition of the hemolysate restored the kinetic parameters of ghost Ca2(+)-ATPase practically completely, whereas in the presence of exogenous calmodulin only part of Ca2(+)-ATPase activity was recovered. Neither calmodulin nor R24571, a highly potent specific inhibitor of calmodulin-dependent reactions, influenced the Ca2(+)-ATPase activity of permeabilized erythrocytes. At Ca2+ concentrations below 0.7 microM, ouabain (0.5-1 mM) activated whereas at higher Ca2+ concentrations it inhibited the Ca2(+)-ATPase activity. Taking this observation into account the Na+/K(+)-ATPase was determined as the difference of between the ATPase activities in the presence of Na+ and K+ and in the presence of K+ alone. At physiological concentration of Mg2+ (370 microM), the addition of 0.3-1 microM Ca2+ increased Na+/K(+)-ATPase activity by 1.5-3-fold. Higher concentrations of this cation inhibited the enzyme. At low Mg2+ concentration (e.g., 50 microM) only Na+/K(+)-ATPase inhibition by Ca2+ was seen. It was found that at [NaCl] less than 20 mM furosemide was increased ouabain-inhibited component of ATPase in Ca2(+)-free media. This activating effect of furosemide was enhanced with a diminution of [Na+] upto 2 mM and did not reach the saturation level unless the 2 mM of drug was used. The activating effect of furosemide on Na+/K(+)-ATPase activity confirmed by experiments in which the ouabain-inhibited component was measured by the 86Rb+ influx into intact erythrocytes. PMID:2175654

  19. The effects of monovalent and divalent cations on the stability of silver nanoparticles formed from direct reduction of silver ions by Suwannee River humic acid/natural organic matter

    The formation and characterization of AgNPs (silver nanoparticles) formed from the reduction of Ag+ by SRNOM (Suwannee River natural organic matter) is reported. The images of SRNOM-formed AgNPs and the selected area electron diffraction (SAED) were captured by high resolution transmission electron microscopy (HRTEM). The colloidal and chemical stability of SRNOM- and SRHA (Suwannee River humic acid)-formed AgNPs in different ionic strength solutions of NaCl, KCl, CaCl2 and MgCl2 was investigated in an effort to evaluate the key fate and transport processes of these nanoparticles in natural aqueous environments. The aggregation state, stability and sedimentation rate of the AgNPs were monitored by Dynamic Light Scattering (DLS), zeta potential, and UV–vis measurements. The results indicate that both types of AgNPs are very unstable in high ionic strength solutions. Interestingly, the nanoparticles appeared more unstable in divalent cation solutions than in monovalent cation solutions at similar concentrations. Furthermore, the presence of SRNOM and SRHA contributed to the nanoparticle instability at high ionic strength in divalent metallic cation solutions, most likely due to intermolecular bridging with the organic matter. The results clearly suggest that changes in solution chemistry greatly affect nanoparticle long term stability and transport in natural aqueous environments. Highlights: ► Formation of SRNOM-AgNPs under environmentally relevant conditions ► Influence of monovalent versus divalent cations on SRHA- and SRNOM-AgNP stability ► Effect of AgNPs on organic matter removal from water columns

  20. Huntingtin regulates Ca(2+) chemotaxis and K(+)-facilitated cAMP chemotaxis, in conjunction with the monovalent cation/H(+) exchanger Nhe1, in a model developmental system: insights into its possible role in Huntington׳s disease.

    Wessels, Deborah; Lusche, Daniel F; Scherer, Amanda; Kuhl, Spencer; Myre, Michael A; Soll, David R


    Huntington׳s disease is a neurodegenerative disorder, attributable to an expanded trinucleotide repeat in the coding region of the human HTT gene, which encodes the protein huntingtin. These mutations lead to huntingtin fragment inclusions in the striatum of the brain. However, the exact function of normal huntingtin and the defect causing the disease remain obscure. Because there are indications that huntingtin plays a role in Ca(2+) homeostasis, we studied the deletion mutant of the HTT ortholog in the model developmental system Dictyostelium discoideum, in which Ca(2+) plays a role in receptor-regulated behavior related to the aggregation process that leads to multicellular morphogenesis. The D. discoideum htt(-)-mutant failed to undergo both K(+)-facilitated chemotaxis in spatial gradients of the major chemoattractant cAMP, and chemotaxis up a spatial gradient of Ca(2+), but behaved normally in Ca(2+)-facilitated cAMP chemotaxis and Ca(2+)-dependent flow-directed motility. This was the same phenotypic profile of the null mutant of Nhel, a monovalent cation/H(+)exchanger. The htt(-)-mutant also failed to orient correctly during natural aggregation, as was the case for the Nhel mutant. Moreover, in a K(+)-based buffer the normal localization of actin was similarly defective in both htt(-) and nhe1(-) cells in a K(+)-based buffer, and the normal localization of Nhe1 was disrupted in the htt(-) mutant. These observations demonstrate that Htt and Nhel play roles in the same specific cation-facilitated behaviors and that Nhel localization is directly or indirectly regulated by Htt. Similar cation-dependent behaviors and a similar relationship between Htt and Nhe1 have not been reported for mammalian neurons and deserves investigation, especially as it may relate to Huntington׳s disease. PMID:25149514

  1. Transport of monovalent cations and calcium in erythrocytes from spontaneously hypertensive rats: investigations with fractions enriched with young and old cells

    The erythrocytes from two spontaneously hypertensive rat strains (SHR and MHS) differ from those of control strains such as WKY and MNS in showing lower values of the mean volume and higher Na, K-cotransport rates. After 4-hour incubation in the presence of orthovanadate 45Ca levels in the erythrocytes from SHR was twice as high as in those from WKY. Under the same conditions, hemoglobin crystallization occured, this process in SHR erythrocytes took place more intensively. No difference was found in these parameters between MNS and MHS. The fractions enriched with young and old cells remained to display variations in the mean volume of cells. Na, K-cotransport rates, 45Ca levels and hemoglobin crystallization, which were recorded between SHR and WKY. The WKY-SHP hybrids of second generation indicated that only Na,K-cotransport rates of the parameters examined positively correlated with blood pressures. From the findings it was concluded that the differences in the volume of erythrocytes and their permeability for cations were not due to the changed time course of cell aging in the blood bed, but to the specific characteristics of cytoskeleton protein arrangement, which were primarily typical of a rat reticulocytic membrane

  2. The Geometry and Structural Properties of the 4,8,12-Trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene System in the Cationic State. Structures of a Planar Organic Cation with Various Monovalent- and Divalent Anions

    Krebs, Frederik C; Laursen, Bo W.; Johannsen, Ib;


    The geometry of the 4,8,12-trioxa-4,8,12,12c- tetrahydrodibenzo[cd,mn]pyrene system in the cationic state was established by X-ray structural resolution of the salts formed between the cationand various anions. The geometry was found to be planar for the 4,8,12-trioxa-4,8,12,12c- tetrahydrodibenzo...... [cd,mn]pyrenylium and 2,6,10-tri (tert-butyl)-4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyre nylium cations with the monovalentanions I-, BF4-, PF6- AsF6-, HNO3. NO3- and CF3SO3-, and the divalent anions S2O62- and Mo6Cl142-. The salts were found to crystallize in distinct space groups...... following a characteristic pattern. Mixed cation-anion stacking resulted in space groups with high symmetry: Pbca in three cases and R (3) over bar c in one; a temperature study of the latter was made at ten different temperatures. The formation of dimers of anions and cations resulted in lower...

  3. Effects of Loops, Flanking Bases and Monovalent Cations on the Structures of G-Quadruplexes%连接环、末端碱基及一价阳离子对G-四链体结构的影响

    常天俊; 李刚; 赵可旭; 班琳; 卞文秀; 邴涛; 上官棣华


    G-rich tandem repeats sequences are able to fold into structures called G-quadruplexes(G4s). G4s have complicated topological structures, which closely depend on the sequences and the solution conditions. In this work, the effects of loops, flanking bases and monovalent cations on the structure of G4s were investigated by gel electrophoresis, circular dichroism spectra and UV-Melting. The results showed that G4 forming se-quences with short loops were favorable to form parallel structure in K+ solution, and the parallel G4s without flanking bases were able to further form G4 multimers, but the anti-parallel or mixed parallel/anti-parallel G4s were not. The monovalent cations had an influence on the adopted structures; K+ was more favorable for the formation of parallel G4 and G4 multimers than NH+4 and Na+. The addition of non-guanine bases to the termi-nals of parallel G4s, or the transformation of the parallel G4s to non-parallel structures by changing the cations, could inhibit the formation of G4 multimers. Furthermore, loop length could affect the thermo-stability of G4s;G4s with short loops had higher thermo-stability. The G4 multimers showed lower thermo-stability than G4 monomer, and their size and amount became smaller with the temperature increase. These results suggest that G4s with short loops and no flanking bases fold into intramolecular parallel structures firstly, and then form multimers through end stacking. The flanking bases and loops located on the G-quartets at 3'or 5'termi-nal hinder the stacking interactions, and inhibit the multimer assembly. Our results may offer useful clues for the structure and function studies of G4s.%研究了G-四链体中的连接环( Loop)、末端碱基和一价阳离子对其结构的影响,发现在K+溶液中Loop短的序列易形成平行结构,无末端碱基时容易形成多聚体,而反平行或混合平行/反平行的G-四链体则难以形成多聚体;一价阳离子K+, NH+4和Na+促进形成

  4. Selective removal of arsenic and monovalent ions from brackish water reverse osmosis concentrate.

    Xu, Pei; Capito, Marissa; Cath, Tzahi Y


    Concentrate disposal and management is a considerable challenge for the implementation of desalination technologies, especially for inland applications where concentrate disposal options are limited. This study has focused on selective removal of arsenic and monovalent ions from brackish groundwater reverse osmosis (RO) concentrate for beneficial use and safe environmental disposal using in situ and pre-formed hydrous ferric oxides/hydroxides adsorption, and electrodialysis (ED) with monovalent permselective membranes. Coagulation with ferric salts is highly efficient at removing arsenic from RO concentrate to meet a drinking water standard of 10 μg/L. The chemical demand for ferric chloride however is much lower than ferric sulfate as coagulant. An alternative method using ferric sludge from surface water treatment plant is demonstrated as an efficient adsorbent to remove arsenic from RO concentrate, providing a promising low cost, "waste treat waste" approach. The monovalent permselective anion exchange membranes exhibit high selectivity in removing monovalent anions over di- and multi-valent anions. The transport of sulfate and phosphate through the anion exchange membranes was negligible over a broad range of electrical current density. However, the transport of divalent cations such as calcium and magnesium increases through monovalent permselective cation exchange membranes with increasing current density. Higher overall salt concentration reduction is achieved around limiting current density while higher normalized salt removal rate in terms of mass of salt per membrane area and applied energy is attained at lower current density because the energy unitization efficiency decreases at higher current density. PMID:23892312

  5. Interactions of monovalent salts with cationic lipid bilayers

    Pokorná, Šárka; Jurkiewicz, Piotr; Cwiklik, Lukasz; Vazdar, Mario; Hof, Martin


    Roč. 160, č. 2013 (2013), s. 341-358. ISSN 1359-6640 R&D Projects: GA ČR GBP208/12/G016; GA AV ČR GEMEM/09/E006 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : FLUORESCENCE SOLVENT RELAXATION * MOLECULAR-DYNAMICS SIMULATIONS * PHOSPHOLIPID-BILAYERS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.194, year: 2013

  6. Electron transport through monovalent atomic wires

    Lee, Y. J.; Brandbyge, Mads; Puska, M. J.;


    Using a first-principles density-functional method we model electron transport through linear chains of monovalent atoms between two bulk electrodes. For noble-metal chains the transport resembles that for free electrons over a potential barrier whereas for alkali-metal chains resonance states at...

  7. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi


    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  8. Effect of monovalent salt on the conformation of polyelectrolyte-surfactant complexes

    Diehl, A.; Kuhn, P. S.


    We study the conformation of polyelectrolyte-surfactant complexes in the presence of monovalent salt. A simple model for the formation of these structures is presented in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interactions between the hydrocarbon tails of surfactant molecules treated in the spirit of van der Waals theory as an effective attraction. The extension of the polyelectrolyte-surfactant complexes is analyzed as a function of the salt concentration and a discrete conformational transition between a compact globule and an elongated coil is found, in agreement with experimental results for the unfolding transition of a DNA-cationic surfactant complex.

  9. Biosorption of monovalent and divalent ions on baker's yeast.

    Vasudevan, Padma; Padmavathy, V; Dhingra, S C


    Biosorption of monovalent ions Na+ and K+, by deactivated protonated yeast (Saccharomyces cerevisiae) at controlled pH, was compared with biosorption of divalent ions Ca2+ and Mg2+ to help to understand the underlying bindingmechanisms. The adsorption for monovalent ions was accompanied by H+ release. Divalent ions were sorbed by proton displacement, and also an additional mode not accompanied by release of H+. The sorption uptake of both monovalent and divalent metal ions increased with pH in the range 3-7 peaking at 6.75. Equilibrium sorption isotherms at pH = 6.75 showed that the totalmaximum biosorptive capacity for metal ions decreased in the following order: Ca > Mg > Na > or = K. PMID:11991078

  10. Multivalent Protein Assembly Using Monovalent Self-Assembling Building Blocks

    Katja Petkau-Milroy


    Full Text Available Discotic molecules, which self-assemble in water into columnar supramolecular polymers, emerged as an alternative platform for the organization of proteins. Here, a monovalent discotic decorated with one single biotin was synthesized to study the self-assembling multivalency of this system in regard to streptavidin. Next to tetravalent streptavidin, monovalent streptavidin was used to study the protein assembly along the supramolecular polymer in detail without the interference of cross-linking. Upon self-assembly of the monovalent biotinylated discotics, multivalent proteins can be assembled along the supramolecular polymer. The concentration of discotics, which influences the length of the final polymers at the same time dictates the amount of assembled proteins.

  11. Monovalent ions control proliferation of Ehrlich Lettre ascites cells

    Klausen, Thomas Kjaer; Preisler, Sarah; Pedersen, Stine Helene Falsig;


    little effect. Western blots showed reduced chloride intracellular channel CLIC1 and chloride channel ClC-2 expression in the plasma membrane in S compared with G(1). Our results suggest that Na+ regulates ELA cell proliferation by regulating intracellular pH while Cl(-) may regulate proliferation by......Channels and transporters of monovalent ions are increasingly suggested as putative anticarcinogenic targets. However, the mechanisms involved in modulation of proliferation by monovalent ions are poorly understood. Here, we investigated the role of K+, Na+, and Cl(-) ions for the proliferation of...... Ehrlich Lettre ascites (ELA) cells. We measured the intracellular concentration of each ion in G(0), G(1), and S phases of the cell cycle following synchronization by serum starvation and release. We show that intracellular concentrations and content of Na+ and Cl(-) were reduced in the G(0)-G(1) phase...

  12. Actinide cation-cation complexes

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO2+) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO2+; therefore, cation-cation complexes indicate something unique about AnO2+ cations compared to actinide cations in general. The first cation-cation complex, NpO2+·UO22+, was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO2+ species, the cation-cation complexes of NpO2+ have been studied most extensively while the other actinides have not. The only PuO2+ cation-cation complexes that have been studied are with Fe3+ and Cr3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO2+·UO22+, NpO2+·Th4+, PuO2+·UO22+, and PuO2+·Th4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M-1

  13. Self-Assembled Ionophores from Isoguanosine: Diffusion NMR Spectroscopy Clarifies Cation's and Anion's Influence on Supramolecular Structure

    Evan-Salem, Tamar; Frish, Limor; Leeuwen, van Fijs W.B.; Reinhoudt, David N.; Verboom, Willem; Kaucher, Mark S.; Davis, Jeffery T.; Cohen, Yoram


    Cation-templated self-assembly of the lipophilic isoguanosine (isoG 1) with different monovalent cations (M+=Li+, Na+, K+, NH4+, and Cs+) was studied in solvents of different polarity by using diffusion NMR spectroscopy. Previous studies that did not use diffusion NMR techniques concluded that isoG

  14. Monovalent cations regulate expression and activity of the Hak1 potassium transporter in Debaryomyces hansenii

    Martínez, J. L.; Sychrová, Hana; Ramos, J.


    Roč. 48, č. 2 (2011), s. 177-184. ISSN 1087-1845 R&D Projects: GA ČR(CZ) GAP503/10/0307 Institutional research plan: CEZ:AV0Z50110509 Keywords : Debaryomyces hansenii * TRK system * potassium uptake Subject RIV: EE - Microbiology, Virology Impact factor: 3.737, year: 2011

  15. Polarized spectral complexes of optical functions of monovalent mercury iodide

    Sobolev, V. V.; Sobolev, V. Val.; Anisimov, D. V.


    Spectral complexes of optical functions of monovalent mercury iodide Hg2I2 were determined for E ⊥ c and E || c polarizations in the range from 2 to 5.5 eV at 4.2 K. The permittivity and characteristic electron energy loss spectra were expanded in simple components with the determination of their main parameters, including the energy of the maximum and the oscillator strength. The calculations were performed based on known reflectance spectra. Computer programs based on Kramers-Kronig relations and the improved parameter-free method of Argand diagrams were used.

  16. Superconducting state parameters of monovalent and polyvalent amorphous

    In the present study deals, we have calculated superconducting state parameter (SSP) like electron-phonon coupling strength λ, coulomb pseudo potential, μ*, transition temperature Tc, isotope effect exponent α and effective interaction strength N0V of monovalent (Li), divalent (Zn), trivalent (In) and tetravalent (Pb) amorphous. To carry out this work we have used our newly constructed model pseudo potential to describe electron ion interaction along with three different local field correction functions like Hartree, Taylor and Sarkar et al. The present results are found in good agreement with other available theoretical as well as experimental data

  17. Stability Study of Razi Trivalent and Monovalent Oral Poliomyelitis Vaccine

    Soleimani, S.


    Full Text Available Stability studies play a critical role in assuring product quality at all points in the vaccine life cycle. These studies used to determine vaccine expiry date and vaccine efficacy. Accelerated stability and long term stability study performed for three batches of trivalent oral poliomyelitis vaccine (OPV and three batches of monovalent OPV (type1 manufactured by Razi institute. After sampling, the samples tested intervals in months for long term stability and after 48h incubation in 37 0C for accelerated stability. All of quantitative and qualitative control tests including Potency, Sterility, Mycoplasma detection and Physicochemical testes performed in each period. Potency test for trivalent OPV (tOPV in three batches of vaccines until 26 months and in two batches, until 27 months after production, met the specification. Potency test for monovalent OPV (mOPV in all batches of vaccines until 18 month after production met the specification. Sterility, mycoplasma and physicochemical testes on these samples for mOPV and tOPV until expiry date and after that, passed. All batches of vaccines in accelerated stability met the specification after incubation and the reduction titer of vaccines was less than 0.5(-LogCCID50/dose. Results of this research indicated razi polio vaccines are stable for 24 months if the cold chain considered properly.

  18. In search of redox non-innocence between a tetrazine pincer ligand and monovalent copper.

    Hui, Alice K; Lord, Richard L; Caulton, Kenneth G


    The synthesis and characterization of a "super-saturated" six-coordinate complex of monovalent copper (PF6(-) salt) and the potentially oxidizing pincer ligand 2,6, bis-(methyl tetrazinyl)pyridine, btzp, are described. This cation has a structure with the two pincers symmetry related, but each btzp having one short and one long Cu-N(tetrazine) bond; facile exchange is observed between short and long tetrazine donors. The structure shows no evidence of full electron transfer from Cu(+) to tetrazine, and DFT calculations not only confirm this conclusion, but also show that the lowest energy triplet state, an excited state relative to the singlet ground state, has the MLCT character where the electron lost by copper now resides in both tetrazine rings of only one pincer ligand; the two pincers in this excited state are inequivalent, having charged btzp(0) and btzp(-1). The unusual orientation of the distinct tetrazines in the ground state structure of Cu(btzp)2(+) is attributed to charge/dipole attraction unhindered by significant entropy cost. PMID:24718554

  19. Binding of alkaline cations to the double-helical form of gramicidin.

    Chen, Y; Wallace, B.A.


    Gramicidin is a polypeptide antibiotic that forms monovalent cation-specific channels in membrane environments. In organic solvents and in lipids containing unsaturated fatty acid chains, it forms a double-helical "pore" structure, in which two monomers are intertwined. This form of gramicidin can bind two cations inside its lumen, and the crystal structures of both an ion complex and an ion-free form have been determined. In this study, we have used circular dichroism (CD) spectroscopy to ex...

  20. Effects of Hofmeister salt series on gluten network formation: Part I. Cation series.

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


    Different cationic salts were used to investigate the effects of the Hofmeister salt series on gluten network formation. The effects of cationic salts on wheat flour dough mixing properties, the rheological and the chemical properties of the gluten extracted from the dough with different respective salts, were investigated. The specific influence of different cationic salts on the gluten structure formation during dough mixing, compared to the sodium ion, were determined. The effects of different cations on dough and gluten of different flours mostly followed the Hofmeister series (NH4(+), K(+), Na(+), Mg(2+) and Ca(2+)). The impacts of cations on gluten structure and dough rheology at levels tested were relatively small. Therefore, the replacement of sodium from a technological standpoint is possible, particularly by monovalent cations such as NH4(+), or K(+). However the levels of replacement need to take into account sensory attributes of the cationic salts. PMID:27374596

  1. Competitive Effects of 2+ and 3+ Cations on DNA Compaction

    Tongu, C; Yoshikawa, Y; Zinchenko, A A; Chen, N; Yoshikawa, K


    By using single-DNA observation with fluorescence microscopy, we observed the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA with 166 kbp). It was found that divalent cations, such as Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. These experimental observations are inconsistent with the well-established Debye-Huckel scheme regarding the shielding effect of counter ions, which is given as the additivity of contributions of cations with different valences. We interpreted the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counter ions before and after the folding transition of DNA. For the compaction with SPD(3+), we considered the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly-charged polyelectrolyte, double-st...

  2. Monovalent Strep-Tactin for strong and site-specific tethering in nanospectroscopy

    Baumann, Fabian; Bauer, Magnus S.; Milles, Lukas F.; Alexandrovich, Alexander; Gaub, Hermann E.; Pippig, Diana A.


    Strep-Tactin, an engineered form of streptavidin, binds avidly to the genetically encoded peptide Strep-tag II in a manner comparable to streptavidin binding to biotin. These interactions have been used in protein purification and detection applications. However, in single-molecule studies, for example using atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS), the tetravalency of these systems impedes the measurement of monodispersed data. Here, we introduce a monovalent form of Strep-Tactin that harbours a unique binding site for Strep-tag II and a single cysteine that allows Strep-Tactin to specifically attach to the atomic force microscope cantilever and form a consistent pulling geometry to obtain homogeneous rupture data. Using AFM-SMFS, the mechanical properties of the interaction between Strep-tag II and monovalent Strep-Tactin were characterized. Rupture forces comparable to biotin:streptavidin unbinding were observed. Using titin kinase and green fluorescent protein, we show that monovalent Strep-Tactin is generally applicable to protein unfolding experiments. We expect monovalent Strep-Tactin to be a reliable anchoring tool for a range of single-molecule studies.

  3. Thermal stability of β-tricalcium phosphate doped with monovalent metal ions

    The effect of doping β-tricalcium phosphate with monovalent metal ions (lithium, sodium, and potassium ions) on its thermal stability was evaluated using the formation ratio of α-tricalcium phosphate and the rate constant for β-α transformation. The thermal stability of β-tricalcium phosphate doped with monovalent metal ions was higher than that of pure β-tricalcium phosphate, and increased with the amount of metal ions. The increase in stability was attributed to the occupation of all calcium sites including vacancy in β-tricalcium phosphate structure by the calcium ions and monovalent metal ions and the resultant crystal stabilization. However, the thermal stability of β-tricalcium phosphate doped with monovalent metal ions was lower than that of β-tricalcium phosphate doped with magnesium ions. These results indicate that the thermal stability of β-tricalcium phosphate is influenced by the difference in the structural stabilization caused by doping metal ions into different calcium sites in the crystal structure.

  4. Monovalent silicotungstate salts as electrolytes for electrochemical supercapacitors

    Highlights: • Li-, Na-, and K- silicotungstate salts were investigated as electrolytes for EDLC. • All salts are neutral and retained the Keggin structure. • All salt solutions showed high ionic conductivity and wide potential windows. • Carbon EDLCs utilizing these salt electrolytes can achieve a 1.5 V cell voltage. - Abstract: Lithium, sodium, and potassium salts of silicotungstic acid were synthesized and characterized as aqueous neutral electrolytes for electrochemical supercapacitors. The acidity of the aqueous solution and the structure of the solid-state anion were examined to confirm the presence of SiW salts. Ionic conductivity and the electrochemical stability potential window were characterized and compared to a silicotungstic acid solution using metallic blocking electrodes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the performance of carbon EDLC cells enabled by the neutral electrolytes and revealed a 1.5 V cell voltage and good cycle life. The similarities and differences among the three salts are explained based on the properties of cations in these neutral electrolytes

  5. An Acetate Bound Cobalt Oxide Catalyst for Water Oxidation: Role of Monovalent Anions and Cations In Lowering Overpotential

    Dey, Subal; Mondal, Biswajit; Dey, Abhishek


    Co(II) dissolved in acetate buffer at pH 7 is found to be a good water oxidation catalyst (WOC) showing electrocatalytic water oxidation current significantly greater than Co(II) in phosphate buffer under the same conditions owing to the higher solubility of the former. When electrodeposited on ITO/FTO electrodes it forms acetate bound cobalt(II)oxide based material (Co-Ac-WOC) showing catalytic water oxidation current density of 0.1 mA/cm$^{2}$ at 830 mV and 1 mA/cm$^{2}$ at 1 V in a pH 7 bu...

  6. NMR crystallography of monovalent cations in inorganic matrixes: Li+ siting and the local structure of Li+ sites in ferrierites

    Klein, Petr; Dědeček, Jiří; Thomas, Haunani M.; Whittleton, Sarah R.; Pashková, Veronika; Brus, Jiří; Kobera, Libor; Sklenák, Štěpán


    Roč. 51, č. 43 (2015), s. 8962-8965. ISSN 1359-7345 R&D Projects: GA MŠk(CZ) LD14010; GA ČR(CZ) GA15-14007S Institutional support: RVO:61388955 ; RVO:61389013 Keywords : NMR crystallography * lithium * DFT Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 6.834, year: 2014

  7. Monovalent cations enable cell wall turnover of the turnover-deficient lyt-15 mutant of Bacillus subtilis.

    Cheung, H. Y.; Freese, E


    A lyt-15 mutant reported to be unable to turn over the cell wall exhibited the same rate of wall turnover as the standard strain if the medium contained 0.2 M NaCl, which did not affect growth. Cell wall autolysis was also optimal at 0.2 M NaCl.

  8. Treatment of drinking water residuals: comparing sedimentation and dissolved air flotation performance with optimal cation ratios.

    Bourgeois, J C; Walsh, M E; Gagnon, G A


    Spent filter backwash water (SFBW) and clarifier sludge generally comprise the majority of the waste residual volume generated and in relative terms, these can be collectively referred to as combined filter backwash water (CFBW). CFBW is essentially a low-solids wastewater with metal hydroxide flocs that are typically light and slow to settle. This study evaluates the impact of adding calcium and magnesium carbonates to CFBW in terms of assessing the impacts on the sedimentation and DAF separation processes. Representative CFBW samples were collected from two surface water treatment plants (WTP): Lake Major WTP (Dartmouth, Nova Scotia, Canada) and Victoria Park WTP (Truro, Nova Scotia, Canada). Bench-scale results indicated that improvements in the CFBW settled water quality could be achieved through the addition of the divalent cations, thereby adjusting the monovalent to divalent (M:D) ratios of the wastewater. In general, the DAF process required slightly higher M:D ratios than the sedimentation process. The optimum M:D ratios for DAF and sedimentation were determined to be 1:1 and 0.33:1, respectively. It was concluded that the optimisation of the cation balance between monovalent cations (e.g., Na(+), K(+)) and added divalent cations (i.e., Ca(2+), Mg(2+)) aided in the settling mechanism through charge neutralisation-precipitation. The increase in divalent cation concentrations within the waste residual stream promoted destabilisation of the negatively charged colour molecules within the CFBW, thereby causing the colloidal content to become more hydrophobic. PMID:14975650

  9. Effect of cation enrichment on dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface.

    Adams, Ellen M; Casper, Clayton B; Allen, Heather C


    The effect of highly concentrated salt solutions of marine-relevant cations (Na(+), K(+), Mg(2+), and Ca(2+)) on Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) was investigated by means of surface pressure-area isotherms, Brewster angle microscopy (BAM), and infrared reflection-absorption spectroscopy (IRRAS). It was found that monovalent cations and Mg(2+) have similar phase behavior, causing DPPC monolayers to expand, while Ca(2+) induces condensation. All cations disrupted the surface morphology at high cation concentration, resulting in decreased reflectivity from the monolayer. Monolayer refractive index was calculated from BAM image intensity in the liquid condensed phase and decreased with increasing cation concentration, which suggests that orientation of the alkyl chains change. Monovalent ions increase ordering of the alkyl chains, more than divalents, yet have little interaction with the DPPC headgroup. Mg(2+) induces gauche defects in the alkyl chain and increases headgroup hydration at low lipid coverage but increases chain ordering and dehydrates the headgroup at high lipid coverage. Ca(2+) orders alkyl chains and dehydrates the phosphate moiety, independent of lipid phase. At the highest salt concentration investigated, significant narrowing of the asymmetric PO2(-) vibrational mode occurs and is attributed to considerable dehydration of the DPPC headgroup. PMID:27322949

  10. Differential modulation by cations of sigma and phencyclidine binding sites in rat brain

    The present investigation attempted to differentiate haloperidol-sensitive sigma sites (sigma H) from phencyclidine (PCP) binding sites in rat brain membranes. We studied the effects of several cations at physiologically relevant concentrations on the binding of radioligands selective for sigma H sites ([3H]haloperidol, [3H](+)3-PPP**), and [3H](+)SKF10,047, or for PCP sites ([3H]PCP and [3H]TCP). The PCP sites displayed a markedly greater sensitivity to cations than sigma H sites. This property was reflected by a greater extent of inhibition of the binding of PCP-selective relative to sigma H-selective ligands at a given cation concentration, as well as by lower IC50's and by steeper slopes of the cation dose-response curves. Divalent cations were approximately 100 times more potent than monovalent cations. All cations were inhibitory, except Sr2+ and Ba2+ which, at micromolar concentrations, enhanced PCP binding but not sigma H binding. Thus, PCP-selective sites appeared to be distinct from sigma H sites with regards to several aspects of cation modulation. This is consistent with the view that PCP and sigma H sites are distinct molecular entities. Further, the marked cation sensitivity of the PCP site is consistent with the current hypothesis according to which the PCP site is linked to the N-methyl-D-aspartate (NMDA) receptor-cation channel complex

  11. Specificity of the metalloregulator CueR for monovalent metal ions

    Szunyogh, Dániel; Szokolai, Hajnalka; Thulstrup, Peter Waaben; Larsen, Flemming Hofmann; Gyurcsik, Béla; Christensen, Niels Johan; Stachura, Monika Kinga; Hemmingsen, Lars Bo Stegeager; Jancsó, Attila


    Metal-ion-responsive transcriptional regulators within the MerR family effectively discriminate between mono- and divalent metal ions. Herein we address the origin of the specificity of the CueR protein for monovalent metal ions. Several spectroscopic techniques were employed to study Ag(I) , Zn......(II) , and Hg(II) binding to model systems encompassing the metal-ion-binding loop of CueR from E. coli and V. cholerae. In the presence of Ag(I) , a conserved cysteine residue displays a pKa value for deprotonation of the thiol that is close to the physiological pH value. This property is only observed with...... the monovalent metal ion. Quantum chemically optimized structures of the CueR metal site with Cys 112 protonated demonstrate that the conserved Ser 77 backbone carbonyl oxygen atom from the other monomer of the homodimer is "pulled" towards the metal site. A common allosteric mechanism of the...

  12. Monovalent monatomic ions in biological environments : insights from computational biophysics studies

    Zhang, Chao


    Monovalent monoatomic ions (Na+, K+, Cl-, H+) are ubiquitously present in biological systems. They are indispensable for various life functions, such as keeping the heart beating and converting the energy from food. Complementary to experiments, molecular simulations indeed provide a computational microscope to probe the structure, dynamics and energetics of these ions in biological environments. One big challenge of computational studies is to accurately model the potential energy surface of...

  13. Competition between condensation of monovalent and multivalent ions in DNA aggregation

    Burak, Yoram; Ariel, Gil; Andelman, David


    We discuss the distribution of ions around highly charged PEs when there is competition between monovalent and multivalent ions, pointing out that in this case the number of condensed ions is sensitive to short-range interactions, salt, and model-dependent approximations. This sensitivity is discussed in the context of recent experiments on DNA aggregation, induced by multivalent counterions such as spermine and spermidine.

  14. How accurate is Poisson-Boltzmann theory for monovalent ions near highly charged interfaces?

    Bu, Wei; Vaknin, David; Travesset, Alex


    Surface sensitive synchrotron x-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface. A lipid phosphate (dihexadecyl hydrogen-phosphate) was spread as a monolayer at the air-water interface to control surface charge density. Using anomalous reflectivity off and at the $L_3 $ Cs$^{+}$ resonance, we provide spatial counterion (Cs$^{+}$) distributions next to the negatively charged interfaces. Five decades in bulk concentrations a...

  15. Aggregation of rod-like polyelectrolyte chains in the presence of monovalent counterions

    Varghese, Anoop; Rajesh, R.; Vemparala, Satyavani


    Using molecular dynamics simulations, it is demonstrated that monovalent counterions can induce aggregation of similarly charged rod-like polyelectrolyte chains. The critical value of the linear charge density for aggregation is shown to be close to the critical value for the extended-collapsed transition of a single flexible polyelectrolyte chain, and decreases with increasing valency of the counterions. The effective interaction potential between two rod-like polyelectrolyte chains is measu...

  16. Strong monovalent electrolyte imbalances in serum of dogs infected with Babesia canis.

    Zygner, Wojciech; Gójska-Zygner, Olga; Wędrychowicz, Halina


    Canine babesiosis is a systemic tick-borne protozoan disease caused by infection with parasites of the genus Babesia. Acid-base disorders and ion imbalances have been described in dogs infected with Babesia rossi in South Africa. In this paper, the authors describe changes to monovalent ion concentrations and calculated parameters of monovalent ions in 70 dogs naturally infected with B. canis, a species occurring in Europe. Hyponatraemia, hypokalaemia, hyperchloraemia, decrease of chloride gap, strong ion gap, difference between sodium and chloride concentrations, and an increase of chloride-to-sodium and sodium-to-potassium ratios were the most prevalent changes. Hyponatraemia, hypokalaemia and hyperchloraemia were detected less frequently than in dogs infected with B. rossi, but the severity of these changes were similar. Comparison of monovalent ion concentrations in azotaemic and non-azotaemic, and anaemic and non-anaemic dogs infected with B. canis showed that azotaemic dogs had significantly lower sodium concentrations. The results of this study indicate a possible development of hyperchloraemic acidosis and the probable contribution of aldosterone in the development of hypokalaemia. However, further study on blood gas, aldosterone, and antidiuretic hormone in dogs infected with B. canis is needed. PMID:22463923

  17. Stimulation of cation transport in mitochondria by gramicidin and truncated derivatives

    Gramicidin and the truncated derivatives desformylgramicidin (desfor) and des(formylvalyl)gramicidin (desval) stimulate monovalent cation transport in rat liver mitochondria. Cation fluxes were compared indirectly from the effect of cations on the membrane potential at steady state (state 4) or from the associated stimulation of electron transport. Rb+ transport was measured directly from the uptake of 86Rb. The truncated gramicidins show enhanced selectivity for K+ and Rb+ when compared to gramicidin. Moreover, the pattern of selectivity within the alkali cation series is altered. The cation fluxes through the truncated derivatives are more strongly dependent on the cation concentration. The presence of high concentrations of permeating cation enhances the transport of other cations through the truncated derivative channels, suggesting that cations are required for stabilizing the channel structure. In high concentrations of KCl, desfor and desval are nearly as effective as gramicidin in collapsing the mitochondrial membrane potential, and consequently, in the uncoupling of oxidative phosphorylation and enhancement of ATP hydrolysis. Preliminary experiments with liposomes show that 86Rb exchange is stimulated by desfor and desval almost to the same extend at gramicidin. These results strongly suggest that the truncated gramicidins form a novel conducting channel which differs from the gramicidin head-to-head, single-stranded β6.3-helical dimer (channel) in its conductance characteristic and its structure. On the basis of the secondary structure of the truncated derivatives, the authors suggest that the antiparallel double-stranded helix dimer (pore) is a likely alternative structure for this novel channel

  18. Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5ee03874j Click here for additional data file.

    Matsui, Taisuke; Seo, Ji-Youn; Domanski, Konrad; Correa-Baena, Juan-Pablo; Nazeeruddin, Mohammad Khaja; Zakeeruddin, Shaik M.; Tress, Wolfgang; Abate, Antonio; Hagfeldt, Anders; Grätzel, Michael


    Today's best perovskite solar cells use a mixture of formamidinium and methylammonium as the monovalent cations. With the addition of inorganic cesium, the resulting triple cation perovskite compositions are thermally more stable, contain less phase impurities and are less sensitive to processing conditions. This enables more reproducible device performances to reach a stabilized power output of 21.1% and ∼18% after 250 hours under operational conditions. These properties are key for the industrialization of perovskite photovoltaics.

  19. Biosorption of radiocesium by deinococcus radiodurans influenced by cations

    Deinococcus radiodurans has a strong ability to withstand high doses of radiation, which makes it as an ideal candidate for bioremediation of sites contaminated with radionuclides and toxic chemicals. However, no data is available on whether D. radiodurans has a specific sorption capacity to radiocesium for bioremediation purpose. The radiocesium biosorption capacity of live cells of D. radiodurans in the presence of other interfering cations was investigated. The maximum biosorption capacity of radiocesium by D. radiodurans in equilibrium state was about 2,100 kBq/kg (fresh weight basis). Among the tested monovalent cations, NH4+ had the strongest antagonism on 134Cs biosorption for D. radiodurans. However, this antagonism could only be observed at a concentration as high as 100 mmol/L. Divalent cations, such as Ca2+ and Pb2+ could reduced the biosorption of radiocesium by D. radiodurans. Al3+ and Cr3+ were cytotoxic to D. radiodurans cells, the growth of D. radiodurans cells was inhibited when the concentrations of these cations were greater than 1 mmol/L. (authors)

  20. Evaluation of monovalent and multivalent iminosugars to modulate Candida albicans β-1,2-mannosyltransferase activities.

    Hurtaux, Thomas; Sfihi-Loualia, Ghenima; Brissonnet, Yoan; Bouckaert, Julie; Mallet, Jean-Maurice; Sendid, Boualem; Delplace, Florence; Fabre, Emeline; Gouin, Sébastien G; Guérardel, Yann


    β-1,2-Linked oligomannosides substitute the cell wall of numerous yeast species. Several of those including Candida albicans may cause severe infections associated with high rates of morbidity and mortality, especially in immunocompromised patients. β-1,2-Mannosides are known to be involved in the pathogenic process and to elicit an immune response from the host. In C. albicans, the synthesis of β-mannosides is under the control of a family of nine genes coding for putative β-mannosyltransferases. Two of them, CaBmt1 and CaBmt3, have been shown to initiate and prime the elongation of the β-mannosides on the cell-wall mannan core. In the present study, we have assessed the modulating activities of monovalent and multivalent iminosugar analogs on these enzymes in order to control the enzymatic bio-synthesis of β-mannosides. We have identified a monovalent deoxynojirimycin (DNJ) derivative that inhibits the CaBmt1-catalyzed initiating activity, and mono-, tetra- and polyvalent deoxymannojirimycin (DMJ) that modulate the CaBmt1 activity toward the formation of a single major product. Analysis of the aggregating properties of the multivalent iminosugars showed their ability to elicit clusterization of both CaBmt1 and CaBmt3, without affecting their activity. These results suggest promising roles for multivalent iminosugars as controlling agents for the biosynthesis of β-1,2 mannosides and for monovalent DNJ derivative as a first target for the design of future β-mannosyltransferase inhibitors. PMID:26852253

  1. Absorption Spectroscopy Analysis of Calcium-Phosphate Glasses Highly Doped with Monovalent Copper.

    Jiménez, José A


    CaO-P2 O5 glasses with high concentrations of monovalent copper ions were prepared by a simple melt-quench method through CuO and SnO co-doping. Spectroscopic characterization was carried out by optical absorption with the aim of analyzing the effects of Cu(+) ions on the optical band-gap energies, which were estimated on the basis of indirect-allowed transitions. The copper(I) content is estimated in the CuO/SnO-containing glasses after the assessment of the concentration dependence of Cu(2+) absorption in the visible region for CuO singly doped glasses. An exponential dependence of the change in optical band gaps (relative to the host) with Cu(+) concentration is inferred up to about 10 mol %. However, the entire range is divided into two distinct linear regions that are characterized by different rates of change with respect to concentration: 1) below 5 mol %, where the linear dependence presents a relatively high magnitude of the slope; and 2) from 5-10 mol %, where a lower magnitude of the slope is manifested. With increasing concentration, the mean Cu(+) -Cu(+) interionic distance decreases, thereby decreasing the sensitivity of monovalent copper for light absorption. The decrease in optical band-gap energies is ultimately shown to follow a linear dependence with the interionic distance, suggesting the potential of the approach to gauge the concentration of monovalent copper straightforwardly in amorphous hosts. PMID:26919120

  2. Longer-term efficacy of a prophylactic monovalent human papillomavirus type 16 vaccine

    Rowhani-Rahbar, Ali; Mao, Constance; Hughes, James P.; Alvarez, Frances B.; Bryan, Janine T; Stephen E., Hawes; Weiss, Noel S.; Koutsky, Laura A.


    We conducted an extended follow-up study (March 2006 – May 2008) to assess the longer-term efficacy of a prophylactic monovalent human papillomavirus (HPV) type 16 L1 virus-like particle vaccine in women (n = 290) who had enrolled in a randomized controlled trial of this vaccine during October 1998 – November 1999 in Seattle and remained HPV-16 DNA negative during the course of that trial. During the extended follow-up period, none of the vaccine recipients was found to be infected with HPV-1...

  3. Predicting 3D structure, flexibility and stability of RNA hairpins in monovalent and divalent ion solutions

    Shi, Ya-Zhou; Wang, Feng-Hua; Zhu, Xiao-Long; Tan, Zhi-Jie


    A full understanding of RNA-mediated biology would require the knowledge of three-dimensional (3D) structures, structural flexibility and stability of RNAs. To predict RNA 3D structures and stability, we have previously proposed a three-bead coarse-grained predictive model with implicit salt/solvent potentials. In this study, we will further develop the model by improving the implicit-salt electrostatic potential and involving a sequence-dependent coaxial stacking potential to enable the model to simulate RNA 3D structure folding in divalent/monovalent ion solutions. As compared with the experimental data, the present model can predict 3D structures of RNA hairpins with bulge/internal loops (<77nt) from their sequences at the corresponding experimental ion conditions with an overall improved accuracy, and the model also makes reliable predictions for the flexibility of RNA hairpins with bulge loops of different length at extensive divalent/monovalent ion conditions. In addition, the model successfully pred...

  4. Cationic cellulose nanofibers from waste pulp residues and their nitrate, fluoride, sulphate and phosphate adsorption properties.

    Sehaqui, Houssine; Mautner, Andreas; Perez de Larraya, Uxua; Pfenninger, Numa; Tingaut, Philippe; Zimmermann, Tanja


    Cationic cellulose nanofibers (CNF) having 3 different contents of positively charged quaternary ammonium groups have been prepared from waste pulp residues according to a water-based modification method involving first the etherification of the pulp with glycidyltrimethylammonium chloride followed by mechanical disintegration. The cationic nanofibers obtained were observed by scanning electron microscopy and the extent of the reaction was evaluated by conductometric titration, ζ-potential measurements, and thermogravimetric analyses. The cationic CNF had a maximum cationic charge content of 1.2mmolg(-1) and positive ζ-potential at various pH values. Sorption of negatively charged contaminants (fluoride, nitrate, phosphate and sulphate ions) and their selectivity onto cationic CNF have been evaluated. Maximum sorption of ∼0.6mmolg(-1) of these ions by CNF was achieved and selectivity adsorption studies showed that cationic CNF are more selective toward multivalent ions (PO4(3-) and SO4(2-)) than monovalent ions (F(-) and NO3(-)). In addition, we demonstrated that cationic CNF can be manufactured into permeable membranes capable of dynamic nitrate adsorption by utilizing a simple paper-making process. PMID:26453885

  5. Cationic lipid membranes-specific interactions with counter-ions

    Ryhaenen, Samppa J; Saeily, V Matti J; Kinnunen, Paavo K J [Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine, Biomedicum, University of Helsinki, PO Box 63 (Haartmaninkatu 8), Helsinki FIN-00014 (Finland)


    Lipids bearing net electric charges in their hydrophilic headgroups are ubiquitous in biological membranes. Recently, the interest in cationic lipids has surged because of their potential as non-viral transfection vectors. In order to utilize cationic lipids in transfer of nucleic acids and to elucidate the role of charged lipids in cellular membranes in general, their complex interactions within the membrane and with the molecules in the surrounding media need to be thoroughly characterized. Yet, even interactions between monovalent counter-ions and charged lipids are inadequately understood. We studied the interactions of the cationic gemini surfactant (2R,3R)-2,3-dimethoxy-1,4- bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (RR-1) with chloride, bromide, fluoride, and iodide as counter-ions by differential scanning calorimetry and Langmuir balance. Chloride interacts avidly with RR-1, efficiently condensing the monolayer, decreasing the collapse pressure, and elevating the main transition temperature. With bromide and iodide clearly different behaviour was observed, indicating specific interactions between RR-1 and these counter-ions. Moreover, with fluoride as a counter-ion and in pure water identical results were obtained, demonstrating inefficient electrostatic screening of the headgroups of RR-1 and suggesting fluoride being depleted on the surface of RR-1 membranes.

  6. Cationic lipid membranes-specific interactions with counter-ions

    Lipids bearing net electric charges in their hydrophilic headgroups are ubiquitous in biological membranes. Recently, the interest in cationic lipids has surged because of their potential as non-viral transfection vectors. In order to utilize cationic lipids in transfer of nucleic acids and to elucidate the role of charged lipids in cellular membranes in general, their complex interactions within the membrane and with the molecules in the surrounding media need to be thoroughly characterized. Yet, even interactions between monovalent counter-ions and charged lipids are inadequately understood. We studied the interactions of the cationic gemini surfactant (2R,3R)-2,3-dimethoxy-1,4- bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (RR-1) with chloride, bromide, fluoride, and iodide as counter-ions by differential scanning calorimetry and Langmuir balance. Chloride interacts avidly with RR-1, efficiently condensing the monolayer, decreasing the collapse pressure, and elevating the main transition temperature. With bromide and iodide clearly different behaviour was observed, indicating specific interactions between RR-1 and these counter-ions. Moreover, with fluoride as a counter-ion and in pure water identical results were obtained, demonstrating inefficient electrostatic screening of the headgroups of RR-1 and suggesting fluoride being depleted on the surface of RR-1 membranes

  7. Contribution to the physicochemical investigation of monovalent thallium and tetravalent uranium fluorides

    Ionic transport properties are studied in monovalent elements and tetravalent uranium fluorides and oxyfluorides. Crystal structure of the oxyfluoride: TlUsub(2.75)OF10 was determined by X-ray diffraction on a monocrystal. The particular role played by oxygen is evidenced in the stabilization of the crystal structure based on an original arrangement of Archimedes antiprisms: UOF7 corresponding to a long distance order oxygen-fluorine in the anionic network. Electric conductivity measurements in AC by the complex impedance method or in DC by the Van der Pauw method allowed performance estimation of these materials which are solid electrolytes. Correlations between electrical properties and structure give information in basic diffusion mechanism in these materials

  8. Solvation of monovalent anions in formamide and methanol: Parameterization of the IEF-PCM model

    The thermodynamics of solvation for a series of monovalent anions in formamide and methanol has been studied using the polarizable continuum model (PCM). The parameterization of this continuum model was guided by molecular dynamics simulations. The parameterized PCM model predicts the Gibbs free energies of solvation for 13 anions in formamide and 16 anions in methanol in very good agreement with experimental data. Two sets of atomic radii were tested in the definition of the solute cavities in the PCM and their performances are evaluated and discussed. Mean absolute deviations of the calculated free energies of solvation from the experimental values are in the range of 1.3-2.1 kcal/mol

  9. International collaboration to assess the risk of Guillain Barre Syndrome following Influenza A (H1N1) 2009 monovalent vaccines

    Dodd, Caitlin N.; Romio, Silvana A.; Black, Steven; Vellozzi, Claudia; Andrews, Nick; Sturkenboom, Miriam; Zuber, Patrick; Hua, Wei; Bonhoeffer, Jan; Buttery, Jim; Crawford, Nigel; Deceuninck, Genevieve; de Vries, Corinne; De Wals, Philippe; Gutierrez-Gimeno, M. Victoria; Heijbel, Harald; Hughes, Hayley; Hur, Kwan; Hviid, Anders; Kelman, Jeffrey; Kilpi, Tehri; Chuang, S. K.; Macartney, Kristine; Rett, Melisa; Lopez-Callada, Vesta Richardson; Salmon, Daniel; Sanchez, Francisco Gimenez; Sanz, Nuria; Silverman, Barbara; Storsaeter, Jann; Thirugnanam, Umapathi; van der Maas, Nicoline; Yih, Katherine; Zhang, Tao; Izurieta, Hector


    Background: The global spread of the 2009 novel pandemic influenza A (H1N1) virus led to the accelerated production and distribution of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1). This pandemic provided the opportunity to evaluate the risk of Guillain-Barre syndrome (GBS), which has been an

  10. Two-phase coexistence in the monovalent-to-divalent phase transition of dineopentylbiferrocene-fluorotetracyanoquinodimethane [npBifc-(F1TCNQ)3], charge-transfer salt

    We present experimental findings showing that for npBifc-(F1TCNQ)3, two phases coexist over a wide temperature interval of 100-150 K near the monovalent-to-divalent phase transition temperature. Macroscopic domains of the high-temperature (monovalent) and low-temperature (divalent) phases were detected in the transition temperature region using X-ray diffraction and micro-Raman spectroscopy techniques. The volume fraction of the two domains continuously varied depending upon the temperature. A considerably large volume difference was found between the monovalent and divalent phases. The effect of volumetric strain due to this volume difference is discussed to understand this inhomogeneous state. (author)

  11. Cation-cation interaction in neptunyl(V) compounds

    The original manuscript was prepared by Professor N.N. Krot of Institute of Physical Chemistry, Russian Academy of Sciences, in 1997. Saeki tried to translate that into Japanese and to add some new data since 1997. The contents include the whole picture of cation-cation interactions mainly in 5-valence neptunium compounds. Firstly, characteristic structures of neptunium are summarized of the cation-cation bonding in compounds. Secondly, it is mentioned how the cation-cation bonding affects physical and chemical properties of the compounds. Then, characterization-methods for the cation-cation bonding in the compounds are discussed. Finally, the cation-cation interactions in compounds of other actinide-ions are shortly reviewed. (author)

  12. The interactions between cationic cellulose and Gemini surfactant in aqueous solution.

    Zhao, Shaojing; Cheng, Fa; Chen, Yu; Wei, Yuping


    Due to the extensive application of cationic cellulose in cosmetic, drug delivery and gene therapy, combining the improvement effect of surfactant-cellulose complexes, to investigate the properties of cellulose in aqueous solution is an important topic from both scientific and technical views. In this study, the phase behavior, solution properties and microstructure of Gemini surfactant sodium 5-nonyl-2-(4-(4-nonyl-2-sulfonatophenoxy)butoxy)phenyl sulfite (9-4-9)/cationic cellulose (JR400, the ammonium groups are directly bonded to the hydroxyethyl substituent with a degree substitution of 0.37) mixture was investigated using turbidity, fluorescence spectrophotometer and shear rheology techniques. As a control, the interaction of corresponding monovalent surfactant, sodium 2-ethoxy-5-nonylbenzenesulfonate (9-2) with JR400 in aqueous solution was also studied. Experimental results showed that 9-4-9/JR400 mixture has lower critical aggregation concentration (CAC) and critical micelle concentration (CMC) (about one order of magnitude) than 9-2/JR400 mixture. A low concentration of Gemini surfactant 9-4-9 appeared to induce an obvious micropolarity and viscosity value variation of the mixture, while these effects required a high concentration of corresponding monovalent one. Furthermore, dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements illuminated the formation and collapse procedure of network structure of the 9-4-9/JR400 mixture, which resulted in the increase and decrease of viscosity. These results suggest that the molecular structure of the surfactant has a great effect on its interaction with cationic cellulose. Moreover, the Gemini surfactant/cationic cellulose mixture may be used as a potencial stimuli-responsive drug delivery vector which not only load hydrophilic drugs, but also deliver hydrophobic substances. PMID:26876997

  13. Compliance with future emission standards of mobile machines by developing a monovalent natural gas combustion process

    Within the presented project a monovalent natural gas engine is being developed. Based on a serial diesel engine the operation mode of this prototype is changed to a spark ignition concept. The long term purpose of this new engine is an agricultural application. One major objective of the project is the investigation and evaluation of a combustion process, able to fulfil the performance requests as well as the European emission limits for nitrogen oxides NOx, and carbon monoxide CO of mobile machinery, which become into law in October 2014 (EU stage IV). At the time there are no legislative regulations existing regarding the methane emissions of the observed engines. To get a benefit in greenhouse gas emissions compared to diesel or gasoline engines the methane emissions have to be minimized while operating in natural gas mode. In the course of the current project an engine operation with a methane emission less than 0.5 g/kWh (representing the EURO VI limit for heavy duty vehicles) could be demonstrated. In contrast to diesel engines for agricultural applications it is possible to comply with the emission standards without using a high sophisticated after treatment system consisting of diesel oxidation catalyst (DOC), particulate filter (DPF) and SCR catalyst. The usage of a three way catalyst optimized for high methane conversions is sufficient for a stoichiometry gas operation with exhaust gas recirculation. Therefore a significant cost advantage is given.

  14. Excited state fluorescence quenching of the U O2++ ion by monovalent anions

    The reactions of the Uranyl ion U O2++ in the excited state with the monovalent inorganic ions N O3- and I O3- in aqueous solutions at normal temperature were studied, using three techniques: Fluorescence in the steady state - Flash photolysis - Fluorescence decay after excitation. With increasing concentration of these ions it was observed a decrease in the normalized intensity and a decrease in the decay time of the fluorescence of the Uranyl ion in the solution and a corresponding appearance of the radicals N O3. or I O3.. In each case the radical was identified by its optical absorption spectrum. These results suggest that the quenching of fluorescence of the Uranyl ion in each case is owing to an electron transfer reaction. In the case of the Nitrate ion the transfer may occur after the formation of an ionic par (U O2+...N O3) in the ground state. Evidence for static quenching in the system Uranyl iodate was not forthcoming. A mechanism for the determination of the velocity constant (probability per ion pair per unit time) is proposed for each of the systems. (author)

  15. In Vitro Neutralisation of Rotavirus Infection by Two Broadly Specific Recombinant Monovalent Llama-Derived Antibody Fragments

    Farah Aladin; Einerhand, Alexandra W. C.; Janneke Bouma; Sandra Bezemer; Pim Hermans; Danielle Wolvers; Kate Bellamy; Frenken, Leon G J; Jim Gray; Miren Iturriza-Gómara


    textabstractRotavirus is the main cause of viral gastroenteritis in young children. Therefore, the development of inexpensive antiviral products for the prevention and/or treatment of rotavirus disease remains a priority. Previously we have shown that a recombinant monovalent antibody fragment (referred to as Anti-Rotavirus Proteins or ARP1) derived from a heavy chain antibody of a llama immunised with rotavirus was able to neutralise rotavirus infection in a mouse model system. In the presen...

  16. Formation of globules and aggregates of DNA chains in DNA/polyethylene glycol/monovalent salt aqueous solutions

    Kawakita, H.; Uneyama, T.; Kojima, M; Morishima, K.; Masubuchi, Y.; Watanabe, H.(Max-Planck-Institut für Kernphysik, 69117, Heidelberg, Germany)


    It has been known that giant DNA shows structural transitions in aqueous solutions under the existence of counterions and other polymers. However, the mechanism of these transitions has not been fully understood. In this study, we directly observed structures of probed (dye-labeled), dilute DNA chains in unprobed DNA/polyethylene glycol (PEG)/monovalent salt (NaCl) aqueous solutions with fluorescent microscopy to examine this mechanism. Specifically, we varied the PEG molecular weight and sal...

  17. Establishment of an in vivo potency assay for the recombinant hepatit is B surface antigen in monovalent and combined vaccines

    Mabel Izquierdo-López; Karelia Cosme-Diaz; Gerardo García-Illera; Zoe Núñez-Lamotte; Yamila Martínez- Cuéllar; Maribel Vega-Simón; Lourdes Costa-Anguiano; Marisel Quintana-Esquivel; Ileana Rosales-Torres; Omar Mosqueda-Lobaina


    In this paper the development of potency assay in animals (mice) was made, with the objective of demonstrating the immunogenic power of the recombinant Hepatitis B surface antigen in monovalent and combined vaccines, produced at the Center of Genetic Engineering and Biotechnology. The potency test is a parameter in quality control and it is also a tool to demonstrate the consistency of the production process. Parameters such as duration of the test, number of animals in the test, ...

  18. Change Color Effect and Spectral Properties of Gold Nanoparticle-cationic Surfactants System

    JIANG Zhi-liang; PAN Hong-cheng; YUAN Wei-en


    The change color effect of gold nanoparticle solutions was studied by means of resonance scattering and absorption spectrometry and scan electron microscopy. The red Au nanoparticles with a size of 10 nm exhibit a resonance absorption peak and a resonance scattering peak all at 525 nm. After some inorganic electrolyte was added to a red Au nanoparticles solution, the color of the solution became blue and the absorbance at 600-700 nm was significantly increased. The ratio of the concentration of monovalent cations, at which the resonance scattering of the system at 525 nm is maximal to that of divalent cations, is in the range of 100 : 1 -100 : 1.8. It is in good agreement with the Schulze-Hardy rule of the coagulation value of electrolyte. After adding some cationic surfactants to the above solution, the color of the solution is in deep blue, with two resonance absorption peaks at 550 and 680 nm, and a greatly enhanced resonance scattering peak at 525 nm.The experiments demonstrate that the stronger the hydrophobicity of the cationic surfactant is, the stronger the change color effect of the Au nanoparticle solution promoted by cationic surfactant is. The change color effect of Au nanoparticle solution is resulted from the increased diameter of Au nanoparticles, and the changes of resonance absorption peak and resonance scattering.

  19. On the real performance of cation exchange resins in wastewater treatment under conditions of cation competition: the case of heavy metal pollution.

    Prelot, Benedicte; Ayed, Imen; Marchandeau, Franck; Zajac, Jerzy


    Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberlite™ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents containing other monovalent (Effluent 1) or divalent (Effluent 2) metal cations, as well as nitrate, borate, or carbonate anions. The individual sorption isotherms of each main component were measured by the solution depletion method. The differential molar enthalpy changes accompanying the ion-exchange between Cs+ or Sr2+ ions and protons at the resin surface from single-component nitrate solutions were measured by isothermal titration calorimetry and they showed a higher specificity of the two resins toward cesium. Compared to the retention limits of both resins under such idealized conditions, an important depression in the maximum adsorption capacity toward each main component was observed in multication systems. The overall effect of ion exchange process appeared to be an unpredictable outcome of the individual sorption capacities of the two resins toward various cations as a function of the cation charge, size, and concentration. The cesium retention capacity of the resins was diminished to about 25% of the "ideal" value in Effluent 1 and 50% in Effluent 2; a further decrease to about 15% was observed upon concomitant strontium addition. The uptake of strontium by the resins was found to be less sensitive to the addition of other metal components: the greatest decrease in the amount adsorbed was 60% of the ideal value in the two effluents for Amberlite® IRN77 and 75% for Amberlite™ IRN9652. It was therefore demonstrated that any performance tests carried out under idealized conditions should be exploited with much caution to predict the real performance of cation exchange resins under conditions of cation competition. PMID:24728575

  20. Evolutionary and structural perspectives of plant cyclic nucleotide-gated cation channels

    Zelman, Alice K.


    Ligand-gated cation channels are a frequent component of signaling cascades in eukaryotes. Eukaryotes contain numerous diverse gene families encoding ion channels, some of which are shared and some of which are unique to particular kingdoms. Among the many different types are cyclic nucleotide-gated channels (CNGCs). CNGCs are cation channels with varying degrees of ion conduction selectivity. They are implicated in numerous signaling pathways and permit diffusion of divalent and monovalent cations, including Ca2+ and K+. CNGCs are present in both plant and animal cells, typically in the plasma membrane; recent studies have also documented their presence in prokaryotes. All eukaryote CNGC polypeptides have a cyclic nucleotide-binding domain and a calmodulin binding domain as well as a six transmembrane/one pore tertiary structure. This review summarizes existing knowledge about the functional domains present in these cation-conducting channels, and considers the evidence indicating that plant and animal CNGCs evolved separately. Additionally, an amino acid motif that is only found in the phosphate binding cassette and hinge regions of plant CNGCs, and is present in all experimentally confirmed CNGCs but no other channels was identified. This CNGC-specific amino acid motif provides an additional diagnostic tool to identify plant CNGCs, and can increase confidence in the annotation of open reading frames in newly sequenced genomes as putative CNGCs. Conversely, the absence of the motif in some plant sequences currently identified as probable CNGCs may suggest that they are misannotated or protein fragments. 2012 Zelman, Dawe, Gehring and Berkowitz.

  1. Multi-scale simulation studies on interaction between anionic surfactants and cations

    Siwei Meng


    Full Text Available In this paper, a dissipative particle dynamics (DPD simulation method was used to investigate the impact of cations on the rheological properties of dodecyl sulfonate surfactant solutions. In order to obtain reasonable interaction between head groups of the surfactant, the geometric structure and interaction between dodecyl sulfonate and cations are optimized using density function theory (DFT at the B3LYP/6-31G level. The DFT calculated results indicate that α-methylene nearest the head group can be classified as a part of the polar head. After binding, the charge on polar head decreases, thus greatly reduces the repulsion between the head groups. It is found that the presence of counterions is one of induction factors on the formation of wormlike micelles, thus greatly enhances the viscosity of surfactant solution. With the increasing in shear strengthen, the wormlike micelles are gradually oriented in the x direction and then broken up into small spherical micelles. This process is also shown by the decrease of viscosity, which decreases quickly at the low shear rates, then keeps almost a constant at the moderate shear rates and at last decreases again at the shear rates larger than a critical value. Compared with monovalent cations, divalent cations have a stronger effect on the rheological properties of dodecyl sulfonate solutions.

  2. A cation binding motif stabilizes the compound I radical of cytochrome c peroxidase.

    Miller, M A; Han, G W; Kraut, J


    Cytochrome c peroxidase reacts with peroxide to form compound I, which contains an oxyferryl heme and an indolyl radical at Trp-191. The indolyl free radical has a half-life of several hours at room temperature, and this remarkable stability is essential for the catalytic function of cytochrome c peroxidase. To probe the protein environment that stabilizes the compound I radical, we used site-directed mutagenesis to replace Trp-191 with Gly or Gln. Crystal structures of these mutants revealed a monovalent cation binding site in the cavity formerly occupied by the side chain of Trp-191. Comparison of this site with those found in other known cation binding enzymes shows that the Trp-191 side chain resides in a consensus K+ binding site. Electrostatic potential calculations indicate that the cation binding site is created by partial negative charges at the backbone carbonyl oxygen atoms of residues 175 and 177, the carboxyl end of a long alpha-helix (residues 165-175), the heme propionates, and the carboxylate side chain of Asp-235. These features create a negative potential that envelops the side chain of Trp-191; the calculated free energy change for cation binding in this site is -27 kcal/mol (1 cal = 4.184J). This is more than sufficient to account for the stability of the Trp-191 radical, which our estimates suggest is stabilized by 7.8 kcal/mol relative to a Trp radical in solution. PMID:7972020

  3. Combined theoretical and experimental study of the site-specificity of vibrational dynamics of CO adsorbed on monovalent metal cations in zeolites

    Bludský, Ota; Nachtigallová, Dana; Bulánek, R.; Nachtigall, Petr


    Roč. 158, - (2005), s. 625-632. ISSN 0167-2991 R&D Projects: GA MŠk(CZ) LC512 Institutional research plan: CEZ:AV0Z4055905 Keywords : IR spectra * FER zeolite * carbon - monoxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.307, year: 2005

  4. Safety of Pandemic (H1N1) 2009 Monovalent Vaccines in Taiwan: A Self-Controlled Case Series Study

    Wan-Ting Huang; Hsu-Wen Yang; Tzu-Lin Liao; Wan-Jen Wu; Shu-Er Yang; Yi-Chien Chih; Jen-Hsiang Chuang


    In Taiwan, new H1N1 monovalent vaccines without adjuvant and with MF59® adjuvant were used in the nationwide vaccination campaign beginning on November 1, 2009. From November 2009 through February 2010, the authors identified recipients of H1N1 vaccines who were diagnosed with adverse events of special interest (AESIs) in a large-linked safety database, and used the self-controlled case series (SCCS) method to examine the risk of each AESI in the 0-42 days after H1N1 vaccination. Of the 3.5 m...

  5. Assessment of epicutaneous testing of a monovalent Influenza A (H1N1) 2009 vaccine in egg allergic patients

    Pitt Tracy; Kalicinsky Chrystyna; Warrington Richard; Cisneros Nestor


    Abstract Background H1N1 is responsible for the first influenza pandemic in 41 years. In the fall of 2009, an H1N1 vaccine became available in Canada with the hopes of reducing the overall effect of the pandemic. The purpose of this study was to assess the safety of administering 2 different doses of a monovalent split virus 2009 H1N1 vaccine in egg allergic patients. Methods Patients were skin tested to the H1N1 vaccine in the outpatient paediatric and adult allergy and immunology clinics of...

  6. Cationic Antimicrobial Peptide Cytotoxicity

    Laverty, Garry; Gilmore, Brendan


    Fluorescence microscopy serves as a valuable tool for assessing the structural integrity and viability of eukaryotic cells. Through the use of calcein AM and the DNA stain 4,6-diamidino-2 phenylindole (DAPI), cell viability and membrane integrity can be qualified. Our group has previously shown the ultra-short cationic antimicrobial peptide H-OOWW-NH2; the amphibian derived 27-mer peptide Maximin-4and the ultra-short lipopeptide C12-OOWW-NH2 to be effective against a range of bacterial biofil...

  7. Establishment of an in vivo potency assay for the recombinant hepatit is B surface antigen in monovalent and combined vaccines

    Mabel Izquierdo-López


    Full Text Available In this paper the development of potency assay in animals (mice was made, with the objective of demonstrating the immunogenic power of the recombinant Hepatitis B surface antigen in monovalent and combined vaccines, produced at the Center of Genetic Engineering and Biotechnology. The potency test is a parameter in quality control and it is also a tool to demonstrate the consistency of the production process. Parameters such as duration of the test, number of animals in the test, as well as different areas for the maintenance of the animals were evaluated. The results on the applicability of the potency test, to two presentations of the vaccines; monovalent Heberbiovac HB and pentavalent liquid in one vial Heberpenta-L are shown, for which specificity studies, evaluating different vaccine lots, the behavior of linearity, and parallelism, as well as establishing quality specification of the test were performed. This assay led to the obtainment of reliable results for the vaccines evaluated, the consistent evaluation of the immunogenic power and the monitoring of different production processes.

  8. The importance of cerium substituted phosphates as cation exchanger some unique properties and related application potentials

    Seven different samples of an inorganic ion exchanger, cerium phosphate, suitable for column use have been prepared under varying conditions. The property of these exchangers has been characterized by Inductively Coupled Plasma Spectroscopy. These exchangers are stable in water, dilute mineral acids, ethanol, methanol, acetone and ether. However, in concentrated HCl and HNO3 they decompose. They retain about 50% of their exchange value after drying at 80 degC, and can be regenerated twice without any decrease in exchange capacity. The distribution coefficient measurements for alkaline earth metals, tellurium, iodine and molybdenum using these seven ion exchangers were studied. This revealed the relative affinity for each exchanger, where the sorption in general was most effective at P H 6-8. The titration curves of cerium phosphate (disodium) with alkaline earth metals showed that the selectivity sequence Ba2+>Sr2+>CA2+>Mg2+ is observed. Furthermore, it could be deduced that the adsorption of alkaline earth metal cations greatly depends on the cation. These studies have also shown that cerium phosphates with divalent ions are strongly preferred to monovalent ones. Therefore, as for the cerium phosphates with large monovalent ions, the lack of exchange for Ba2+, Mg2+ or other alkaline earth metal ions should be essentially due to steric hindrance and this could include any one of the following: the large crystalline radius of metal ions or large hydrated ionic radius and high energy of hydration for other divalent ions. Three binary separations of TeIV - MoIV, TeIV -I1 has been developed and the recovery ranging from 90 to 100% has been achieved on cerium phosphate (disodium) columns

  9. The effects of mono- and divalent metal cations on the solution structure of caffeine and theophylline

    Nafisi, Shohreh; Monajemi, Majid; Ebrahimi, Saeedeh


    The interactions of caffeine and theophylline with potassium +, cobalt 2+ and nickel 2+ ions were studied in aqueous solution at physiological pH with constant ligand concentration and various metal ion contents. Fourier Transform infrared spectroscopy and absorption spectra were used to determine the cation binding mode and association constants. Spectroscopic results showed direct and indirect cation interactions for Co 2+, Ni 2+ and K + through O6 and N9 atoms (caffeine) and O6, N9 and N7 atoms (theophylline). The overall binding constants were, K(Co-caffeine)=6.92×10 4 M -1, K(Ni-caffeine)=2.22×10 4 M -1, K(K-caffeine)=5.08×10 3 M -1, K(Co-theophylline)=5.06×10 4 M -1, K(Ni-theophylline)=4.84×10 4 M -1 and K(K-theophylline)=2.13×10 3 M -1. The association constants showed weaker interaction for monovalent cation than divalent metal ions.

  10. Synergistic Interactions of Sugars/Polyols and Monovalent Salts with Phospholipids Depend upon Sugar/Polyol Complexity and Anion Identity.

    Clark, Ginevra A; Henderson, J Michael; Heffern, Charles; Akgün, Bülent; Majewski, Jaroslaw; Lee, Ka Yee C


    We found that interactions of dipalmitoylphosphatidylcholine (DPPC) lipid monolayers with sugars are influenced by addition of NaCl. This work is of general importance in understanding how sugar-lipid-salt interactions impact biological systems. Using Langmuir isothermal compressions, fluorescence microscopy, atomic force microscopy, and neutron reflectometry, we examined DPPC monolayers upon addition of sugars/polyols and/or monovalent salts. Sugar-lipid interactions in the presence of NaCl increased with increasing complexity of the sugar/polyol in the order glycerol ≪ glucose lithium ions may also compete with glucose for binding sites. Thus, both cooperative and competitive factors contribute to the overall influence of salts on sugar-lipid interactions. PMID:26496486

  11. International collaboration to assess the risk of Guillain Barré Syndrome following Influenza A (H1N1) 2009 monovalent vaccines

    C. Dodd (Caitlin); S.A. Romio (Silvana); S. Black (Steve); C. Vellozzi (Claudia); N.J. Andrews (Nick); M.C.J.M. Sturkenboom (Miriam); P. Zuber (Patrick); W. Hua (Wei); J. Bonhoeffer (Jan); J. Buttery (Jim); N. Crawford (Nigel); G. Deceuninck (Genevieve); C.S. de Vries (Corinne); P. de Wals (Philippe); D. Gimeno (David); H. Heijbel (Harald); H. Hughes (Hayley); K. Hur (Kwan); A. Hviid (Anders); J. Kelman (Jeffrey); T. Kilpi (Tehri); S.K. Chuang (S.); T. Macartney (Thomas); M. Rett (Melisa); V.R. Lopez-Callada (Vesta Richardson); D. Salmon (Daniel); F.G. Sanchez (Francisco Gimenez); N. Sanz (Nuria); B. Silverman (Bernard); J. Storsaeter (Jann); U. Thirugnanam (Umapathi); N.A.T. van der Maas (Nicoline); K. Yih (Katherine); T. Zhang (Teng Fei); H.S. Izurieta (Hector); B.J. Addis; A. Akhtar (Aysha); J. Cope (Judith); R.L. Davis (Robert); P. Gargiullo (Paul); X. Kurz (Xavier); B. Law (Barbara); I. Sahinovic (Isabelle); J. Tokars (Jerry); P. Serrano (Pedro); A. Cheng (Aixin); N.J. Andrews (Nick); P. Charles (Pat); H. Clothier (Hazel); B. Day (Bruce); T. Day (Timothy); P. Gates (Peter); R. MacDonnell (Richard); L. Roberts (Les); V. Rodriguez-Casero (Vic-toria); T. Wijeratne (Tissa); H.A.L. Kiers; C. Blyth (Christopher); R. Booy (Robert); E. Elliott (Elizabeth); M.R. Gold (Michael); H. Marshall; P. McIntyre (Peter); P. Richmond (Peter); J. Royle (Jenny); N.W. Wood (Nicholas); Y. Zurynski (Yvonne); G. Calvo (Gonzalo); M. Campins (Magda); N. Corominas (Nuria); F. Torres (Ferran); V. Valls; A. Vilella (Ángels); A. Dutra (Amalia); A. Eick-Cost (Angelia); H.M. Jackson (Henry); K. Garman (Katherine); Z. Hu (Zheng); J. Rigo; J. Badoo (Judith); D Cho (David); L.L. Polakowski (Laura); S.K. Sandhu (Sukhminder); G. Sun (Guoying); H.-S.S. Chan (Hoi-Shan Sophelia); K.-Y. Chan (Kwok-Yin); R. Cheung (Raymond); Y-F. Cheung (Yuk-Fai); S. Cherk (Sharon); S.K Chuang (S.); D. Fok (Dennis); B.-H. Fung (Bun-Hey); K.-F. Ko (Kwai-Fu); K.W. Lau (Ka Wing); K.-K. Lau (Kwok-Kwong); P. Li (Pulin); H.-T. Liu (Hui-Tung); S.-H. Liu (Shao-Haei); K. Mok (Kin); J. So (Joanna); W. Wong (Winnie); S.-P. Wu (Shun-Ping); V. Avagyan (Vardan); R. Ball (Robert); D. Burwen (Dale); R.L. Franks (Riley); J.M. Gibbs (Jonathan); R.E. Kliman (Rebecca); S. Kropp (Silke); T.E. MaCurdy (Thomas); D.B. Martin (David); S.-D.K. Sandhu (Sukhmin-Der); B.B. Worrall (Bradford B.); D.E.F. Fuentes (Dra. Elvira Fuentes); P.C.O. González (Paola Carolina Ojeda); V.F. Reyna (Valerie ); R. Vázquez (Rolando); M. Kulldorff (Martin); G. Lee (Grace); T.A. Lieu (Tracy); S. Platt; G.D. Serres (Gaston De); K. Jabin (Kamilah); B.L.S. Soh (Bee Leng Sally); L. Arnheim-Dahlström (Lisen); A. Castot (Anne); H.E. de Melker (Hester); J.P. Dieleman (Jeanne); J. Hallgren (Jonal); B.C. Jacobs (Bart); K. Johansen (Kari); P Kramarz (Piotr); M. Lapeyre (Maryse); T. Leino (Tuija); D. Mølgaard-Nielsen (Ditte); M. Mosseveld (Mees); H.K. Olberg (Henning K); C.-M. Sammon (Cor-Mac); C. Saussier (Christel); M.J. Schuemie (Martijn); A. Sommet (Agnès); P. Sparen (Pär); H. Svanström (Henrik); A.M. Vanrolleghem (Ann M.); D.M. Weibel (Daniel); J.D. Domingo (Javier Diez); J.L. Esparza (José LuísMicó); R.M.O. Lucas (Rafael M. Ortí); J.B.M. Maseres (Juan B. Mollar); J.L.A. Sánchez (José Luís Alfonso); M.G. Sánchez (Mercedes Garcés); V.Z. Viguer (Vicente Zanón); F. Cunningham (Francesca); B. Thakkar (Bharat); R. Zhang (Rongping)


    textabstractBackground: The global spread of the 2009 novel pandemic influenza A (H1N1) virus led to the accelerated production and distribution of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1). This pandemic provided the opportunity to evaluate the risk of Guillain-Barré syndrome (GBS), which

  12. Immunogenicity and safety of monovalent RIVM meningococcal B OMP vesicle F91 vaccine administered to children that received hexavalent meningococcal B vaccine 2.5 years ago

    Lafeber AB; van Limpt CJP; Berbers GAM; Labadie J; de Kleijn ED; de Groot R; Rumke HC; van Alphen AJW; LVO


    Dit rapport beschrijft een follow-up studie naar veiligheid en immunogeniciteit van monovalent P1.7h,4 OMV vaccin (MonoMen) gebruikt als boostervaccinatie in kinderen eerder gevaccineerd met hexavalent MenB vaccin. De deelnemers aan deze studie zijn in het kader van een eerdere studie gevaccineerd

  13. Ion exchange behaviour of polymeric zirconium cations

    Polymeric zirconium cations formed in weakly acid solutions (pH2) are taken up strongly into macroporous cation exchange resins, while uptake into normal cation exchange resins (pore diameter about 1 nm) is low. Macroporous cation exchange resins loaded with polymeric Zr cations are shown to function as ligand exchange sorbents. (Authors)

  14. Energy Transfer Assays Using Quantum Dot-Gold Nanoparticle Complexes: Optimizing Oligonucleotide Assay Configuration Using Monovalently Conjugated Quantum Dots.

    Uddayasankar, Uvaraj; Krull, Ulrich J


    The energy transfer between quantum dots (QDs) and gold nanoparticles (AuNPs) represents a popular transduction scheme in analytical assays that use nanomaterials. The impact of the spatial arrangement of the two types of nanoparticles on analytical performance has now been evaluated using a nucleic acid strand displacement assay. The first spatial arrangement (configuration 1) involved the assembly of a number of monovalently functionalized QD-oligonucleotide conjugates around a single central AuNP that was functionalized with complementary oligonucleotide sequences. The assembly of these complexes, and subsequent disassembly via target oligonucleotide-mediated displacement, were used to evaluate energy transfer efficiencies. Furthermore, the inner filter effect of AuNPs on the fluorescence intensity of the QD was studied. AuNPs of three different diameters (6, 13, and 30 nm) were used in these studies. Configuration 2 was based on the placement of monovalently functionalized AuNP-oligonucleotide conjugates around a single QD that was functionalized with a complementary oligonucleotide. The optimal assay configuration, established by evaluating energy transfer efficiencies and inner filter effects, was obtained by arranging at most 15 QDs around the 13 nm AuNP (configuration 1). These assays provided a 2.5-fold change in fluorescence intensity in the presence of target oligonucleotides. To obtain the same response with configuration 2 required the placement of three 6 nm AuNPs around the QD. This resulted in configuration 2 having a 5-fold lower fluorescence intensity when compared to configuration 1. The use of low-cost detection systems (digital camera) further emphasized the higher analytical performance of configuration 1. Response curves obtained using these detection systems demonstrated that configuration 1 had a 10-fold higher sensitivity when compared to configuration 2. This study provides an important framework for the development of sensitive assays

  15. Liquid-solid extraction of cationic metals by cationic amphiphiles

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl-, NO3-, C2O42-) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author)

  16. Safety of pandemic (H1N1 2009 monovalent vaccines in taiwan: a self-controlled case series study.

    Wan-Ting Huang

    Full Text Available In Taiwan, new H1N1 monovalent vaccines without adjuvant and with MF59® adjuvant were used in the nationwide vaccination campaign beginning on November 1, 2009. From November 2009 through February 2010, the authors identified recipients of H1N1 vaccines who were diagnosed with adverse events of special interest (AESIs in a large-linked safety database, and used the self-controlled case series (SCCS method to examine the risk of each AESI in the 0-42 days after H1N1 vaccination. Of the 3.5 million doses of H1N1 vaccines administered and captured in the linked database, the SCCS analysis of Guillain-Barré syndrome (GBS found an incidence rate ratio of 3.81 (95% confidence interval 0.43-33.85 within 0-42 days after nonadjuvanted H1N1 vaccination and no cases after MF59®-adjuvanted H1N1 vaccination. The risks of other AESIs were, in general, not increased in any of the predefined postvaccination risk periods and age groups. The databases and infrastructure created for H1N1 vaccine safety evaluation may serve as a model for safety, effectiveness and coverage studies of licensed vaccines in Taiwan.

  17. Monovalent Ions and Water Dipoles in Contact with Dipolar Zwitterionic Lipid Headgroups-Theory and MD Simulations

    Aljaž Velikonja


    Full Text Available The lipid bilayer is a basic building block of biological membranes and can be pictured as a barrier separating two compartments filled with electrolyte solution. Artificial planar lipid bilayers are therefore commonly used as model systems to study the physical and electrical properties of the cell membranes in contact with electrolyte solution. Among them the glycerol-based polar phospholipids which have dipolar, but electrically neutral head groups, are most frequently used in formation of artificial lipid bilayers. In this work the electrical properties of the lipid layer composed of zwitterionic lipids with non-zero dipole moments are studied theoretically. In the model, the zwitterionic lipid bilayer is assumed to be in contact with aqueous solution of monovalent salt ions. The orientational ordering of water, resulting in spatial variation of permittivity, is explicitly taken into account. It is shown that due to saturation effect in orientational ordering of water dipoles the relative permittivity in the zwitterionic headgroup region is decreased, while the corresponding electric potential becomes strongly negative. Some of the predictions of the presented mean-field theoretical consideration are critically evaluated using the results of molecular dynamics (MD simulation.

  18. Noninferiority of Antibody Response to Human Papillomavirus Type 16 in Subjects Vaccinated with Monovalent and Quadrivalent L1 Virus-Like Particle Vaccines▿

    Garland, Suzanne M; Steben, Marc; Hernandez-Avila, Mauricio; Koutsky, Laura A.; Wheeler, Cosette M.; Perez, Gonzalo; Harper, Diane M.; Leodolter, Sepp; Tang, Grace W. K.; Ferris, Daron G; Esser, Mark T.; Vuocolo, Scott C.; Nelson, Micki; Railkar, Radha; Sattler, Carlos


    The incorporation of multiple antigens into a single human papillomavirus (HPV) vaccine may induce immune interference. To evaluate whether interference occurs when HPV type 16 (HPV16) virus-like particles are combined in a multivalent vaccine, we conducted a study to evaluate anti-HPV16 responses among subjects receiving three-dose regimens of either a monovalent HPV16 vaccine or a quadrivalent HPV (types 6, 11, 16, and 18) vaccine.

  19. Structure of a cation-bound multidrug and toxic compound extrusion transporter

    He, Xiao; Szewczyk, Paul; Karyakin, Andrey; Evin, Mariah; Hong, Wen-Xu; Zhang, Qinghai; Chang, Geoffrey (Scripps)


    Transporter proteins from the MATE (multidrug and toxic compound extrusion) family are vital in metabolite transport in plants, directly affecting crop yields worldwide. MATE transporters also mediate multiple-drug resistance (MDR) in bacteria and mammals, modulating the efficacy of many pharmaceutical drugs used in the treatment of a variety of diseases. MATE transporters couple substrate transport to electrochemical gradients and are the only remaining class of MDR transporters whose structure has not been determined. Here we report the X-ray structure of the MATE transporter NorM from Vibrio cholerae determined to 3.65 {angstrom}, revealing an outward-facing conformation with two portals open to the outer leaflet of the membrane and a unique topology of the predicted 12 transmembrane helices distinct from any other known MDR transporter. We also report a cation-binding site in close proximity to residues previously deemed critical for transport. This conformation probably represents a stage of the transport cycle with high affinity for monovalent cations and low affinity for substrates.

  20. In-vitro Neurotoxicity of Two Malaysian Krait Species (Bungarus candidus and Bungarus fasciatus Venoms: Neutralization by Monovalent and Polyvalent Antivenoms from Thailand

    Muhamad Rusdi Ahmad Rusmili


    Full Text Available Bungarus candidus and Bungarus fasciatus are two species of krait found in Southeast Asia. Envenoming by these snakes is often characterized by neurotoxicity and, without treatment, causes considerable morbidity and mortality. In this study, the in vitro neurotoxicity of each species, and the effectiveness of two monovalent antivenoms and a polyvalent antivenom, against the neurotoxic effects of the venoms, were examined in a skeletal muscle preparation. Both venoms caused concentration-dependent inhibition of indirect twitches, and attenuated responses to exogenous nicotinic receptor agonists, in the chick biventer preparation, with B. candidus venom being more potent than B. fasciatus venom. SDS-PAGE and western blot analysis indicated different profiles between the venoms. Despite these differences, most proteins bands were recognized by all three antivenoms. Antivenom, added prior to the venoms, attenuated the neurotoxic effect of the venoms. Interestingly, the respective monovalent antivenoms did not neutralize the effects of the venom from the other Bungarus species indicating a relative absence of cross-neutralization. Addition of a high concentration of polyvalent antivenom, at the t90 time point after addition of venom, partially reversed the neurotoxicity of B. fasciatus venom but not B. candidus venom. The monovalent antivenoms had no significant effect when added at the t90 time point. This study showed that B. candidus and B. fasciatus venoms display marked in vitro neurotoxicity in the chick biventer preparation and administration of antivenoms at high dose is necessary to prevent or reverse neurotoxicity.

  1. Cationic speciation in nonaqueous media

    Electronic spectra of solutions of d transition elements in the superacids HF, H2SO4, HSO3F, and CF3SO3H and in chloroaluminate melts indicate that in acidic monaqueous media the elements are present as solvated cations, whereas in basic media the speciation is anionic, the same situation as in aqueous solutions. Further, in very highly acidic media, cations in very low oxidation states are stable (e.g., Ti2+), but these disproportionate on addition of base to the system. In this paper spectra, where available, of U, Np, and Pu in oxidation states III and IV in aqueous media, in protonic superacids, and in chloroaluminates are presented to postulate cationic speciation of these early actinides in highly acidic media

  2. Research progress in cation-π interactions


    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system,which has been viewed as a new kind of binding force,as being compared with the classical interactions(e.g. hydrogen bonding,electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper,we present an overview of the typical cation-π interactions in biological systems,the experimental and theoretical investigations on cation-π interactions,as well as the research results on cation-π interactions in our group.

  3. Coverage and side effects of influenza A(H1N1) 2009 monovalent vaccine among primary health care workers.

    Ortiz Arjona, Miguel Angel; Abd Elaziz, Khaled Mahmoud; Caballero Lanzas, Jose Maria; Allam, Mohamed Farouk


    In June 2009, WHO declared the maximum phase alert against H1N1 pandemic flu. Health care workers (HCWs) are considered a strategic target for prevention of the occurrence of H1N1 influenza since they had the greatest risk of acquiring infection. The objectives of our study were (1) identifying the uptake of influenza A(H1N1) 2009 monovalent vaccine by primary health care workers in the southern part of Cordoba, and (2) reporting of the adverse events occurred after vaccination. We followed 240 HCWs in 12 primary health care centres at southern part of Cordoba for vaccine uptake and the occurrence of adverse events. The coverage rate with H1N1 vaccine was 20.5% which was lower compared to seasonal influenza vaccination rate 44.2% in 2009. Males had higher H1N1 vaccination rate compared to females with no significant difference. Senior HCWs complied more with seasonal influenza vaccine while this finding was not consistent with H1N1 vaccination. Multivariate analysis showed that the only independent variable that affected H1N1 vaccine was the compliance to the seasonal flu vaccine in the past three years with OR 5.1 and 95% CI (2.4-10.8). Adverse events occurred among 26.5% of those who complied with H1N1 vaccination. Those were local pain, irritation and induration at site of injection (38.5%), fever (15.4%), fever cough and rhinorrhea (15.4%) generalized pain and lumber pains (23.1%). The low vaccination rate in this study is consistent with previous studies done in many parts of the world and in Spain. Further studies should be done to explore the factors that hindered the uptake and resistance of HCWs to vaccination to H1N1 vaccine. PMID:21840463

  4. Development by Genetic Immunization of Monovalent Antibodies (Nanobodies) Behaving as Antagonists of the Human ChemR23 Receptor.

    Peyrassol, Xavier; Laeremans, Toon; Gouwy, Mieke; Lahura, Vannessa; Debulpaep, Maja; Van Damme, Jo; Steyaert, Jan; Parmentier, Marc; Langer, Ingrid


    The generation of Abs that recognize the native conformation of G protein-coupled receptors can be a challenging task because, like most multimembrane-spanning proteins, they are extremely difficult to purify as native protein. By combining genetic immunization, phage display, and biopanning, we identified two functional monovalent Abs (nanobodies) targeting ChemR23. The two nanobodies (CA4910 and CA5183) were highly specific for the human receptor and bind ChemR23 with moderate affinity. Binding studies also showed that they share a common binding site that overlaps with that of chemerin, the natural ligand of ChemR23. Consistent with these results, we found that the nanobodies were able to antagonize chemerin-induced intracellular calcium increase. The inhibition was partial when chemerin was used as agonist and complete when the chemerin(149-157) nonapeptide was used as agonist. Engineering of a bivalent CA4910 nanobody resulted in a relatively modest increase in affinity but a marked enhancement of efficacy as an antagonist of chemerin induced intracellular calcium mobilization and a much higher potency against the chemerin(149-157) nonapeptide-induced response. We also demonstrated that the fluorescently labeled nanobodies detect ChemR23 on the surface of human primary cell populations as efficiently as a reference mouse mAb and that the bivalent CA4910 nanobody behaves as an efficient antagonist of chemerin-induced chemotaxis of human primary cells. Thus, these nanobodies constitute new tools to study the role of the chemerin/ChemR23 system in physiological and pathological conditions. PMID:26864035

  5. Impact of sediment-seawater cation exchange on Himalayan chemical weathering fluxes

    Lupker, Maarten; France-Lanord, Christian; Lartiges, Bruno


    Continental-scale chemical weathering budgets are commonly assessed based on the flux of dissolved elements carried by large rivers to the oceans. However, the interaction between sediments and seawater in estuaries can lead to additional cation exchange fluxes that have been very poorly constrained so far. We constrained the magnitude of cation exchange fluxes from the Ganga-Brahmaputra river system based on cation exchange capacity (CEC) measurements of riverine sediments. CEC values of sediments are variable throughout the river water column as a result of hydrological sorting of minerals with depth that control grain sizes and surface area. The average CEC of the integrated sediment load of the Ganga-Brahmaputra is estimated ca. 6.5 meq 100 g-1. The cationic charge of sediments in the river is dominated by bivalent ions Ca2+ (76 %) and Mg2+ (16 %) followed by monovalent K+ (6 %) and Na+ (2 %), and the relative proportion of these ions is constant among all samples and both rivers. Assuming a total exchange of exchangeable Ca2+ for marine Na+ yields a maximal additional Ca2+ flux of 28 × 109 mol yr-1 of calcium to the ocean, which represents an increase of ca. 6 % of the actual river dissolved Ca2+ flux. In the more likely event that only a fraction of the adsorbed riverine Ca2+ is exchanged, not only for marine Na+ but also Mg2+ and K+, estuarine cation exchange for the Ganga-Brahmaputra is responsible for an additional Ca2+ flux of 23 × 109 mol yr-1, while ca. 27 × 109 mol yr-1 of Na+, 8 × 109 mol yr-1 of Mg2+ and 4 × 109 mol yr-1 of K+ are re-absorbed in the estuaries. This represents an additional riverine Ca2+ flux to the ocean of 5 % compared to the measured dissolved flux. About 15 % of the dissolved Na+ flux, 8 % of the dissolved K+ flux and 4 % of the Mg2+ are reabsorbed by the sediments in the estuaries. The impact of estuarine sediment-seawater cation exchange appears to be limited when evaluated in the context of the long-term carbon cycle and

  6. Liquid-solid extraction of metallic cations by cationic amphiphiles

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  7. Role of cations as components of jelly coats in Bufo arenarum fertilization.

    Medina, Marcela Fátima; Crespo, Claudia Alejandra; Ramos, Inés; Fernández, Silvia Nélida


    The role of monovalent (Na+, K+) and divalent (Ca2+, Mg2+) cations in Bufo arenarum fertilization was analysed. Our results showed that the highest fertilization percentages were obtained when strings of uterine oocytes (UO) were inseminated. Under these conditions, full jelly (FJ), which represents the jelly coats surrounding the oocytes at the time of deposition, contained 68.5 +/- 7.0 mM Na+, 27.4 +/- 2.4 mM K+, 6.3 +/- 0.9 mM Ca2+ and 6.9 +/- 0.9 mM Mg2+. When the strings of oocytes were washed in deionized water, these cations diffused into the liquid medium surrounding them. There was a marked similarity between the loss of Ca2+ in the jelly and the decrease in the fertilizability of the UO. Furthermore, the use of chelating agents of divalent cations showed the importance of the Ca2+ contained in the jelly. When Ca2+ was sequestered from the jelly coats by the addition of the chelating agents to the insemination medium as well as by pretreatment of the UO strings, a decrease in fertilization percentages occurred, this effect being dose dependent and more marked with EGTA. These results demonstrate that the Ca2+ in the jelly plays a role in fertilization. Nevertheless, taking into account that during the washing of the jelly other jelly coat components were diffused and considering that the addition of Ca2+ to the insemination medium reverted significantly, but only partially, the loss of fertilizability of jellied UO (washed), the participation of other components in the fertilization mechanism is suggested. PMID:19664308

  8. Textural characterization of foxtail millet gels: effect of cations and hydrocolloids.

    Nagaprabha, P; Bhattacharya, Sila


    Foxtail millet (Setaria italica) is traditionally cultivated in mainly dry land areas and has nutritional importance. The textural characteristics of gels, formed with foxtail millet flour at different concentrations (9-13 %, dry solid basis) along with selected cations and hydrocolloids, were determined. Different concentrations of monovalent (NaCl) and divalent (CaCl2 and FeSO4) cations, and hydrocolloids such as gelatin, gellan, starch, xanthan and agar were incorporated in gels. The gel forming ability markedly improved with an increase in the concentrations of CaCl2 and FeSO4, while NaCl had a marginal effect. Gels prepared with 11 % of foxtail millet alone were found to sensorially acceptable while addition of 0.5 % CaCl2 or 0.2 % FeSO4 respective with 10 % foxtail millet also resulted in acceptable gels. Among the hydrocolloids, starch and gellan had marked effects on gel formation, and textural and sensory attributes. The principal component analysis (PCA) plot showed that concentration of foxtail millet formed a cluster with sensory hardness, springiness, cohesiveness, and instrumental peak stress, fracture strain and compression energy indicating that these attributes were interrelated to each other. Stickiness and gelling time formed a cluster on the other side of the axis indicating inversely related. Foxtail millet has a good potential for development of new ranges of gelled health benefiting convenience products with nutraceutical property, and the addition of cations helps to achieve acceptable structural integrity. PMID:26787947

  9. Polyelectrolyte Condensation Induced by Linear Cations

    Guáqueta, Camilo; Luijten, Erik


    We examine the role of the condensing agent in the formation of polyelectrolyte bundles, via grand-canonical Monte Carlo simulations. Following recent experiments we use linear, rigid divalent cations of various lengths to induce condensation. Our results clarify and explain the experimental results for short cations. For longer cations we observe novel condensation behavior owing to alignment of the cations. We also study the role of the polyelectrolyte surface charge density, and find a non...

  10. Cationic electrodepositable coating composition comprising lignin

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter


    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  11. Structure of gramicidin D-RbCl complex at atomic resolution from low-temperature synchrotron data: interactions of double-stranded gramicidin channel contents and cations with channel wall

    Glówka, M.L.; Olczak, A.; Bojarska, J.; Szczesio, M.; Duax, W.L.; Burkhart, B.M.; Pangborn, W.A.; Langs, D.A.; Wawrzak, Z. (Poland); (NWU); (Hauptman)


    Gramicidin D (gD) is a naturally occurring ionophoric antibiotic that forms membrane channels specific for monovalent cations. The crystal structure of the RbCl complex of gD has been determined at 1.14 {angstrom} resolution from low-temperature (100 K) synchrotron-radiation data with a final R of 16%. The structure was refined with anisotropic temperature factors for all non-H atoms and with partial occupancies for many of them. The asymmetric unit in the crystal contains four crystallographically independent molecules that form two right-handed antiparallel double-stranded dimers. There are seven distinct rubidium-binding sites in each dimeric channel. The occupancy factors of Rb cations are between 0.11 and 0.35 and the total ion contents of the two crystallographically independent channels are 1.59 and 1.22 ions, respectively. Although each channel is 'chemically symmetrical', the side-chain conformations, the distributions of rubidium cations and their binding sites in the two independent channels are not. Cations are 'coordinated' by delocalized {pi}-electrons of three to five carbonyl groups that together with peptide backbone chains form the gramicidin channel walls. The water:cation ratio in the channel interior is four or five:one, and five or six waters separate Rb cations during their passage through the channel.

  12. Organometallic cation-exchanged phyllosilicates

    Fleming, Shay


    Organotin (IV) complexes formed between 0 01 M dimethyltin dichloride solutions prepared at pH 2 6 and 4 0, and trimethyltin chloride prepared at pH 3 4, with Na- 119 montmori 1lonite clay have been characterised using Sn Mflssbauer spectroscopy, X-ray diffraction, thermogravimetric analysis and water sorption isotherms Following cation exchange, Mttssbauer spectroscopy identified two tin species in the dimethyltin (IV)-exchanged clay prepared at pH 2 6 A cis specie...

  13. Calorimetric study of cationic photopolymerization

    The photopolymerization of penta-erythritol tetra-glycidyl ether (initiator Degacure KI-85) was studied by a du Pont 910 type DSC. From our experimental results the following conclusions can be drawn: (1) During the cationic polymerization reaction the lifetime of the initiating centers are long compared to the lifetime of free radicals in case of radical polymerization. (2) The rate of deactivation of the initiating centers increases with increasing temperature. (author)

  14. Unidirectional Flux Balance of Monovalent Ions in Cells with Na/Na and Li/Na Exchange: Experimental and Computational Studies on Lymphoid U937 Cells

    Vereninov, Igor A.; Yurinskaya, Valentina E.; Model, Michael A.; Vereninov, Alexey A.


    Monovalent ion traffic across the cell membrane occurs via various pathways. Evaluation of individual fluxes in whole cell is hampered by their strong interdependence. This difficulty can be overcome by computational analysis of the whole cell flux balance. However, the previous computational studies disregarded ion movement of the self-exchange type. We have taken this exchange into account. The developed software allows determination of unidirectional fluxes of all monovalent ions via the major pathways both under the balanced state and during transient processes. We show how the problem of finding the rate coefficients can be solved by measurement of monovalent ion concentrations and some of the fluxes. Interdependence of fluxes due to the mandatory conditions of electroneutrality and osmotic balance and due to specific effects can be discriminated, enabling one to identify specific changes in ion transfer machinery under varied conditions. To test the effectiveness of the developed approach we made use of the fact that Li/Na exchange is known to be an analogue of the coupled Na/Na exchange. Thus, we compared the predicted and experimental data obtained on U937 cells under varied Li+ concentrations and following inhibition of the sodium pump with ouabain. We found that the coupled Na/Na exchange in U937 cells comprises a significant portion of the entire Na+ turnover. The data showed that the loading of the sodium pump by Li/Na exchange involved in the secondary active Li+ transport at 1–10 mM external Li+ is small. This result may be extrapolated to similar Li+ and Na+ flux relationships in erythrocytes and other cells in patients treated with Li+ in therapeutic doses. The developed computational approach is applicable for studying various cells and can be useful in education for demonstrating the effects of individual transporters and channels on ion gradients, cell water content and membrane potential. PMID:27159324

  15. Seroprevalence of pandemic H1N1 antibody among health care workers in Hong Kong following receipt of monovalent 2009 H1N1 influenza vaccine.

    Ying Zhou

    Full Text Available BACKGROUND: Healthcare workers in many countries are recommended to receive influenza vaccine to protect themselves as well as patients. A monovalent H1N1 vaccine became available in Hong Kong in December 2009 and around 10% of local healthcare workers had received the vaccine by February 2010. METHODS: We conducted a cross-sectional study of the prevalence of antibody to pandemic (H1N1 2009 among HCWs in Hong Kong in February-March 2010 following the first pandemic wave and the pH1N1 vaccination campaign. In this study we focus on the subset of healthcare workers who reported receipt of non-adjuvanted monovalent 2009 H1N1 vaccine (Panenza, Sanofi Pasteur. Sera collected from HCWs were tested for antibody against the pH1N1 virus by hemagglutination inhibition (HI and viral neutralization (VN assays. RESULTS: We enrolled 703 HCWs. Among 104 HCWs who reported receipt of pH1N1 vaccine, 54% (95% confidence interval (CI: 44%-63% had antibody titer ≥1∶40 by HI and 42% (95% CI: 33%-52% had antibody titer ≥1∶40 by VN. The proportion of HCWs with antibody titer ≥1∶40 by HI and VN significantly decreased with age, and the proportion with antibody titer ≥1∶40 by VN was marginally significantly lower among HCWs who reported prior receipt of 2007-08 seasonal influenza vaccine (odds ratio: 0.43; 95% CI: 0.19-1.00. After adjustment for age, the effect of prior seasonal vaccine receipt was not statistically significant. CONCLUSIONS: Our findings suggest that monovalent H1N1 vaccine may have had suboptimal immunogenicity in HCWs in Hong Kong. Larger studies are required to confirm whether influenza vaccine maintains high efficacy and effectiveness in HCWs.

  16. Assessment of epicutaneous testing of a monovalent Influenza A (H1N1 2009 vaccine in egg allergic patients

    Pitt Tracy


    Full Text Available Abstract Background H1N1 is responsible for the first influenza pandemic in 41 years. In the fall of 2009, an H1N1 vaccine became available in Canada with the hopes of reducing the overall effect of the pandemic. The purpose of this study was to assess the safety of administering 2 different doses of a monovalent split virus 2009 H1N1 vaccine in egg allergic patients. Methods Patients were skin tested to the H1N1 vaccine in the outpatient paediatric and adult allergy and immunology clinics of the Health Sciences Centre and Children's Hospital of Winnipeg, Manitoba Canada. Individuals Results A total of 61 patients with egg allergy (history of an allergic reaction to egg with either positive skin test &/or specific IgE to egg >0.35 Ku/L were referred to our allergy clinics for skin testing to the H1N1 vaccine. 2 patients were excluded, one did not have a skin prick test to the H1N1 vaccine (only vaccine administration and the other passed an egg challenge during the study period. Ages ranged from 1 to 27 years (mean 5.6 years. There were 41(69.5% males and 18(30.5% females. All but one patient with a history of egg allergy, positive skin test to egg and/or elevated specific IgE level to egg had negative skin tests to the H1N1 vaccine. The 58 patients with negative skin testing to the H1N1 vaccine were administered the vaccine and observed for 30 minutes post vaccination with no adverse results. The patient with the positive skin test to the H1N1 vaccine was also administered the vaccine intramuscularly with no adverse results. Conclusions Despite concern regarding possible anaphylaxis to the H1N1 vaccine in egg allergic patients, in our case series 1/59(1.7% patients with sensitization to egg were also sensitized to the H1N1 vaccine. Administration of the H1N1 vaccine in egg allergic patients with negative H1N1 skin tests and observation is safe. Administering the vaccine in a 1 or 2 dose protocol without skin testing is a reasonable alternative

  17. Monovalent indium in a sulfur-rich coordination environment: synthesis, structure and reactivity of tris(2-mercapto-1-tert-butylimidazolyl)hydroborato indium, [TmBut]In.

    Yurkerwich, Kevin; Buccella, Daniela; Melnick, Jonathan G; Parkin, Gerard


    [Tm(Bu(t))]In, the first structurally-characterized monovalent indium compound that features a sulfur-rich coordination environment, has been synthesized via treatment of InCl with [Tm(Bu(t))]K; in contrast to the thallium counterpart, the lone pair of [Tm(Bu(t))]In is a site of reactivity, thereby allowing formation of [Tm(Bu(t))]In-->B(C(6)F(5))(3) and [Tm(Bu(t))]In(kappa(2)-S(4)) upon treatment with B(C(6)F(5))(3) and S(8), respectively. PMID:18622452

  18. Immunogenicity and safety of monovalent RIVM meningococcal B OMP vesicle F91 vaccine administered to children that received hexavalent meningococcal B vaccine 2.5 years ago

    Lafeber AB; Limpt CJP van; Berbers GAM; Labadie J; de Kleijn ED; de Groot R; Rumke HC; van Alphen AJW; LVO


    Dit rapport beschrijft een follow-up studie naar veiligheid en immunogeniciteit van monovalent P1.7h,4 OMV vaccin (MonoMen) gebruikt als boostervaccinatie in kinderen eerder gevaccineerd met hexavalent MenB vaccin. De deelnemers aan deze studie zijn in het kader van een eerdere studie gevaccineerd met hexavalent MenB vesicle vaccin of met HepB vaccin (controle groep). Tijdens de studie traden geen ernstige bijwerkingen op. Systemische bijwerkingen werden vooral gerapporteerd tijdens de 2e en ...

  19. Cation coordination in oxychloride glasses

    Johnson, J. A.; Holland, D.; Bland, J.; Johnson, C. E.; Thomas, M. F.


    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2].

  20. Cation coordination in oxychloride glasses

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2

  1. Cation coordination in oxychloride glasses

    Johnson, J A [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States); Holland, D [Physics Department, Warwick University, Coventry (United Kingdom); Bland, J [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom); Johnson, C E [Physics Department, Northern Illinois University, DeKalb, IL (United States); Thomas, M F [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom)


    Glasses containing mixtures of cations and anions of nominal compositions [Sb{sub 2}O{sub 3}]{sub x} - [ZnCl{sub 2}]{sub 1-x} where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb){sub 2}(OZn)] and [Zn(ClZn){sub 2}(OSb){sub 2}].

  2. Near-UV sensitized 1.06 μm emission of Nd3+ ions via monovalent copper in phosphate glass

    Monovalent copper ions effectively incorporated in Nd-containing phosphate glass by a single-step melt-quench method have been established as near-ultraviolet (UV) sensitizers of Nd3+ ions, resulting in a remarkable 4F3/2 → 4I11/2 emission at 1.06 μm. The spectroscopic data indicates an efficient energy conversion process. The Cu+ ions first absorb photons broadly around 360 nm, and subsequently transfer the energy from the Stokes-shifted emitting states to resonant Nd3+ energy levels in the visible. Ultimately, the Nd3+ electronic excited states decay and the upper lasing state 4F3/2 is populated, leading to the enhanced emission at 1.06 μm. The characteristic features of the Cu+ visible emission spectra and the reduced lifetime of the corresponding Cu+ donor states indicate an efficient non-radiative transfer. The Cu+/Nd3+ co-doped phosphate glass appears suitable as solid-state laser material with enhanced pump range in the near-UV part of the spectrum and for solar spectral conversion in photovoltaic cells. - Graphical abstract: Display Omitted - Highlights: • Monovalent copper ions effectively stabilized in Nd3+-containing phosphate glass. • Enhanced Nd3+ near-infrared emission observed upon the Cu+ ions incorporation. • Cu+ → Nd3+ non-radiative energy transfer efficiencies and likely energy transfer pathways evaluated. • Potential for solid-state lasers and solar spectral conversion suggested

  3. Role of monovalent co-dopants on the PL emission properties of YAl3(BO3)4:Ce3+phosphor

    R Satheesh Kumar; V Ponnusamy; V Sivakumar; MT Jose


    The cerium (Ce3+) doped yttrium aluminium borate (YAB) phosphor was synthesized by modified solid state reaction. The phosphor’s phase purity and its emission properties were studied using powder X-ray diffraction pattern and photoluminescence spec-troscopy. The synthesized YAB had rhomobohedral crystal structure. The phosphor had two different excitation and emission spectra. By 325 nm excitation, the phosphor had emission at 373 nm and with 363 nm excitation;the phosphor gave violet-blue emission at 418 nm. The UV emission of the phosphor originated due to Ce3+ions at the yttrium site and violet-blue emission owing to Ce3+ions at non-regular sites viz., Al3+and interstitial sites. The emission intensity of the phosphor was enhanced when monovalent ions (K+, Na+, and F-) were added as co-dopants. The crucial role of ionic radii of monovalent co-dopants on the emission enhancement of the YAB:Ce3+phosphor was reported. Thermogravimetric study showed that the YAB possessed high thermal stability at up to 900 °C.

  4. Magnetic susceptibility and electron magnetic resonance study of monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3

    Highlights: •Orthorhombic monovalent doped manganites Pr0.6Sr0.4-xKxMnO3 (x = 0.05 to 0.2). •Unit cell volume decreases with K content. •Curie temperature decreases with K content. •Electron magnetic resonance determines low temperature limit of paramagnetic phase. -- Abstract: The monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x = 0.05–0.2) are characterized using the complementary magnetic susceptibility and electron resonance methods. In paramagnetic phase the temperature variations of the inverse magnetic susceptibility and the inverse intensity of resonance signal obey the Curie–Weiss law. A similarity in temperature variation of resonance signal width and the adiabatic polaron conductivity points to the polaron mechanism controlling the resonance linewidth. The low temperature limit of the pure paramagnetic phase is determined from the electron resonance spectra revealing the mixed phase spread down to the Curie temperature

  5. Use of laser induced photoacoustic spectroscopy (LIPAS) to determine equilibrium constants of cation-cation complexes

    Laser Induced PhotoAcoustic Spectroscopy (LIPAS) is a relatively new, photothermal technique to examine solutions. Studies in the past have shown it to be more sensitive than conventional absorption spectroscopy, while, yielding the same information thus allowing lower concentrations to be used. This study is using LIPAS to examine solutions to determine the equilibrium constants of cation-cation complexes. It has been found that actinyl(V) cations form cation-cation complexes with a variety of cations, including actinyl(VI) cations. The radioactive nature of the actinide elements requires special handling techniques and also require limits be placed on the amount of material that can be used. The sensitivity of some oxidation states of the actinides to oxygen also presents a problem. Preliminary results will be presented for actinyl(V)-actinyl(VI) cation-cation complexes that were studied using a remote LIPAS system incorporating fiber optics for transmission of laser signals

  6. The Free Tricoordinated Silyl Cation Problem

    Čičak, H.


    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  7. Anti-inflammatory activity of cationic lipids

    Filion, Mario C; Phillips, Nigel C


    The effect of liposome phospholipid composition has been assumed to be relatively unimportant because of the presumed inert nature of phospholipids.We have previously shown that cationic liposome formulations used for gene therapy inhibit, through their cationic component, the synthesis by activated macrophages of the pro-inflammatory mediators nitric oxide (NO) and tumour necrosis factor-α (TNF-α).In this study, we have evaluated the ability of different cationic lipids to reduce footpad inf...

  8. Anti-inflammatory activity of cationic lipids.

    Filion, M C; Phillips, N C


    1. The effect of liposome phospholipid composition has been assumed to be relatively unimportant because of the presumed inert nature of phospholipids. 2. We have previously shown that cationic liposome formulations used for gene therapy inhibit, through their cationic component, the synthesis by activated macrophages of the pro-inflammatory mediators nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha). 3. In this study, we have evaluated the ability of different cationic lipids to reduce footpad inflammation induced by carrageenan and by sheep red blood cell challenge. 4. Parenteral (i.p. or s.c) or local injection of the positively charged lipids dimethyldioctadecylammomium bromide (DDAB), dioleyoltrimethylammonium propane (DOTAP), dimyristoyltrimethylammonium propane (DMTAP) or dimethylaminoethanecarbamoyl cholesterol (DC-Chol) significantly reduced the inflammation observed in both models in a dose-dependent manner (maximum inhibition: 70-95%). 5. Cationic lipids associated with dioleyol- or dipalmitoyl-phosphatidylethanolamine retained their anti-inflammatory activity while cationic lipids associated with dipalmitoylphosphatidylcholine (DPPC) or dimyristoylphosphatidylglycerol (DMPG) showed no anti-inflammatory activity, indicating that the release of cationic lipids into the macrophage cytoplasm is a necessary step for anti-inflammatory activity. The anti-inflammatory activity of cationic lipids was abrogated by the addition of dipalmitoylphosphatidylethanolamine-poly(ethylene)glycol-2000 (DPPE-PEG2000) which blocks the interaction of cationic lipids with macrophages. 6. Because of the significant role of protein kinase C (PKC) in the inflammatory process we have determined whether the cationic lipids used in this study inhibit PKC activity. The cationic lipids significantly inhibited the activity of PKC but not the activity of a non-related protein kinase, PKA. The synthesis of interleukin-6 (IL-6), which is not dependent on PKC activity for its

  9. Afrikaans Syllabification Patterns

    Tilla Fick


    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  10. Tripodal Receptors for Cation and Anion Sensors

    David N. Reinhoudt


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

  11. Advancements in Anion Exchange Membrane Cations

    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)


    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.

  12. Low-dose aspirin use does not diminish the immune response to monovalent H1N1 influenza vaccine in older adults.

    Jackson, M L; Bellamy, A; Wolff, M; Hill, H; Jackson, L A


    Non-steroidal anti-inflammatory drugs (NSAIDs) may inhibit antibody production by peripheral blood mononuclear cells; one consequence of this could be decreased effectiveness of vaccines in NSAID users. Because many older adults use low-dose aspirin for primary or secondary prevention of coronary events, any inhibitory effect of aspirin on vaccine immune response could reduce the benefits of vaccination programmes in older adults. We tested whether immune response to vaccination differed between users vs. non-users of low-dose aspirin, using data from four randomized trials of monovalent 2009 pandemic influenza A(H1N1) vaccine. Geometric mean haemagglutination inhibition antibody titres were not significantly lower in low-dose aspirin users compared to non-users. Our results provide reassurance that influenza vaccination effectiveness is probably not reduced in older adults taking chronic low-dose aspirin. PMID:26330204

  13. Electrical transport and EPR investigations: A comparative study for d.c. conduction mechanism in monovalent and multivalent ions doped polyaniline

    Suresh Kumar Gupta; Vandna Luthra; Ramadhar Singh


    A detailed comparative study of electron paramagnetic resonance (EPR) in conjunction with d.c. electrical conductivity has been undertaken to know about the charge transport mechanism in polyaniline (PANI) doped with monovalent and multivalent protonic acids. This work is in continuation of our previous work for further understanding the conduction mechanism in conducting polymers. The results reveal that the polarons and bipolarons are the main charge carriers formed during doping process and these cause increase in electrical conductivity not only by increase in their concentration but also because of their enhanced mobility due to increased inter-chain transport in polyaniline at high doping levels. EPR line asymmetry having Dysonian line shape for highly doped samples shows a marked deviation of amplitudes / ratio from values close to one to much high values as usually observed in metals, thereby support the idea of high conductivity at higher doping levels. The nature of dopant ions and their doping levels control the charge carriers concentration as well as electrical conductivity of polyaniline. The electrical conductivity has also been studied as a function of temperature to know the thermally assisted transport process of these charge carriers at different doping levels which has been found to follow the Mott’s variable range hopping (VRH) conduction model for all the three dopants used. The charge carriers show a change over from 3D VRH to quasi 1D VRH hopping process for multivalent ions at higher doping levels whereas 1D VRH has been followed by monovalent ion for full doping range. These studies collectively give evidence of inter-chain percolation at higher doping levels causing increase in effective mobility of the charge carriers which mainly seems to govern the electrical conduction behaviour in this system.

  14. Cationic Bolaamphiphiles for Gene Delivery

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad


    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  15. Cationic ruthenium alkylidene catalysts bearing phosphine ligands

    Endo, Koji; Grubbs, Robert H.


    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bear-ing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions pro-vided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported...

  16. Cation substitution in two coccolithophore species

    Melteig, Hanna Elina


    Few things would be better than getting rid of CO2 while producing useful materials. Coccolithophores use CO2 in their photorespiration, in addition to using CO2 to produce coccoliths – small platelets made of calcite. Ca is a central cation in this process, and the goal of this project is to investigate to what extent other divalent cations can partially substitute for Ca and become part of the growing coccolith. The long term goal is to enable algae to harvest cations and produce mate...

  17. Intracellular NHX-Type Cation/H+ Antiporters inPlants


    Cells depend on the homeostatic maintenance of pHwithin specific cellular compartments to ensure optimalconditions for metabolic and enzymatic processes as wellas protein structure and function. In the animal secre-tory pathway, cells maintain distinct luminal pHs withinvarious compartments (Paroutis et al., 2004). Among themany molecular players that contribute to pH and ionhomeostasis in plants, Na+(K+)/H+ exchangers (also knownas NHX-type cation/H+ antiporters) appear to be particu-larly important for the regulation of a wide variety ofphysiological processes, including cell expansion, cellvolume regulation, osmotic adjustment, pH regulation,membrane trafficking, protein processing, and cellularstress responses (Pardo et al., 2006; Rodriguez-Rosaleset al., 2009; Bassil et al., 2012). In plants, NHX antiportersappeared early in evolution and are ubiquitously encodedmembers of the CPA1 cation/H+ antiporters subgroupthat belongs to the large family of monovalent cation/H+ transporters CPA (Brett et al., 2005). NHX antiport-ers are found, thus far, in all sequenced plant genomes(Bassil et al., 2012; Chanroj et al., 2012). In Arabidopsis,the NHX family consists of eight isoforms, six of whichare intracellular (AtNHXl-AtNHX6), located either to thevacuole (AtNHXl to AtNHX4) or endosomes (AtNHX5 andAtNHX6) and an additional two more divergent members(AtNHX7/SOSl and AtNHX8) at the plasma membrane(Bassil et al., 2012). Orthologous sequences in each of thethree classes (plasma membrane, vacuolar, or endosomal)appear in all sequenced genomes, suggesting that distinctfunctional NHX classes appeared early in evolution andmay have conserved roles that are compartment-specific(Bassil et al., 2012). Emerging new evidence highlightsthe importance of particular intracellular NHX antiport-ers in the regulation of vesicular and vacuolar pH andK+ homeostasis. Vacuolar NHXs are needed to maintainK+ homeostasis

  18. Cationization of heparin for film applications

    Šimkovic, I.; Mendichi, R.; Kelnar, Ivan; Filip, J.; Hricovíni, M.


    Roč. 115, 22 January (2015), s. 551-558. ISSN 0144-8617 Institutional support: RVO:61389013 Keywords : heparin * cationization * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.074, year: 2014

  19. Cation locations and dislocations in zeolites

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  20. Cycloaliphatic epoxide resins for cationic UV - cure

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  1. Test procedure for cation exchange chromatography

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  2. Silica-based cationic bilayers as immunoadjuvants

    Carmona-Ribeiro Ana M; da Costa Maria; Faquim-Mauro Eliana; Santana Mariana RA; Lincopan Nilton


    Abstract Background Silica particles cationized by dioctadecyldimethylammonium bromide (DODAB) bilayer were previously described. This work shows the efficiency of these particulates for antigen adsorption and presentation to the immune system and proves the concept that silica-based cationic bilayers exhibit better performance than alum regarding colloid stability and cellular immune responses for vaccine design. Results Firstly, the silica/DODAB assembly was characterized at 1 mM NaCl, pH 6...

  3. Cations and activated sludge floc structure

    Park, Chul


    This research was designed to investigate the effect of cations on activated sludge characteristics and also to determine their influence on digestion performance. For this purpose, cations in solution and in floc were evaluated along with various activated sludge characteristics and the collected waste activated sludge underwent both anaerobic and aerobic digestion. It was found that large amounts of biopolymer (protein + polysaccharide) remained in the effluent of WWTP that received high in...

  4. Accelerators for forming cationic technetium complexes useful as radiodiagnostic images

    This invention relates to compositions for making cationic radiodiagnostic agents and, in particular, to accelerator compounds for labelling such cationic radiodiagnostic agents, kits for preparing such 99mTc-labelled cationic radiodiagnostic agents with technetium, and methods for labelling such cationic radiodiagnostic agents with technetium

  5. The effect of cations on the aggregation of commercial ZnO nanoparticle suspension

    Nanoscale ZnO materials have been largely used in many products due to their distinct properties. However, ZnO nanoparticles (NPs) are hazardous to human health and the ecosystem. The characteristics and the stability of ZnO NPs are relevant to their fate in the environment and their potential toxicities. In this study, a stable commercial ZnO NP suspension was chosen to investigate its aggregation under various salt additions. Different concentrations of NaCl, KCl and CaCl2 were chosen to represent various environmental conditions. Under pH 8–9, the surface charge of commercial ZnO NPs was negative. The behavior of the stabilized ZnO NPs in water was affected by ionic combinations and ionic strength; that is, divalent cations were more effective than monovalent ones in promoting aggregation formation. The attachment efficiencies of ZnO aggregates were calculated based upon the aggregation kinetics. The critical coagulation concentration values for this commercial ZnO NPs were higher than previous reported for ZnO NPs, indicating this ZnO NP could be stable in the aquatic environment and might have increased hazardous potentials. Based upon the Derjaguin–Landau–Verwey–Overbeek theory, interactions between ZnO NPs in the presence of different ions were evaluated to illustrate the aggregation mechanism. Our results indicated that critical ionic type and concentration promote the aggregation of stable ZnO NPs. These understandings also can facilitate the design of the precipitation treatment to remove NPs from water.

  6. Cationically polymerizable monomers derived from renewable sources

    Crivello, J.V.


    The objective of this project is to make use of products obtained from renewable plant sources as monomers for the direct production of polymers which can be used for a wide range of plastic applications. In this report is described progress in the synthesis and polymerization of cationically polymerizable monomers and oligomers derived from botanical oils, terpenes, natural rubber, and lignin. Nine different botanical oils were obtained from various sources, characterized and then epoxidized. Their photopolymerization was carried out using cationic photoinitiators and the mechanical properties of the resulting polymers characterized. Preliminary biodegradation studies are being conducted on the photopolymerized films from several of these oils. Limonene was cationically polymerized to give dimers and the dimers epoxidized to yield highly reactive monomers suitable for coatings, inks and adhesives. The direct phase transfer epoxidation of squalene and natural rubber was carried out. The modified rubbers undergo facile photocrosslinking in the presence of onium salts to give crosslinked elastomers. 12 refs., 3 figs., 10 tabs.

  7. Cation Effect on Copper Chemical Mechanical Polishing

    WANG Liang-Yong; LIU Bo; SONG Zhi-Tang; FENG Song-Lin


    We examine the effect of cations in solutions containing benzotriazole (BTA) and H2O2 on copper chemical mechanical polishing (CMP). On the base of atomic force microscopy (AFM) and material removal rate (MRR) results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demon-strates the worst performance. These results reveal a mechanism that sma//molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential (OCP).

  8. Adsorption of cationic surfactants and their effects on the interfacial properties of quartz

    Jia, Renhe

    This dissertation is primarily concerned with an investigation of the interfacial behavior of natural quartz in aqueous solution where the adsorption of various cationic surfactants is involved. The broad objective of this research was to delineate the mechanisms involved in the adsorption of cationic surfactants using experimental determination of adsorption isotherms, zeta potentials, suspension turbidity, contact angles, induction times, as well as Hallimond tube flotation response. With dodecylpyridinium chloride as the model surfactant, four-region adsorption isotherms were observed and found to correlate well with zeta potential, suspension stability and contact angle measurements. Calculations of adsorption energy showed strong specific adsorption in Region I, probably resulting from H-bonding of the pyridinium headgroup to active sites on the silica. As a result of hemimicelle formation at the solid-liquid interface in Region II, pronounced increases in the adsorption density, zeta potential, and surface hydrophobicity were observed. The stability of quartz suspensions showed a significant drop in this region. In Region III, the zeta potential is reversed and the stability of the suspensions begins to increase again. In this region, the surface hydrophobicity of quartz decreases with further surfactant adsorption, suggesting reverse orientation of the adsorbed surfactant ions. In Region IV, the adsorption isotherm and zeta potential reach a plateau when the surfactant concentration reaches the CMC, and the surface becomes completely hydrophilic. The molecular structure of surfactant ions (chain length, number of hydrocarbon chains and number of headgroups) was found to significantly affect their surface activity. Increasing the hydrocarbon chain length of the surfactant lowers the concentration of surfactant required for minimum suspension stability, as well as redispersion. The adsorption is stronger for surfactants whose structure permits hydrogen bonding

  9. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    Wasserman, S.R.; Anderson, K.B.; Song, K.; Yuchs, S.E.; Marshall, C.L.


    The problems associated with the disposal of toxic metals in an environmentally acceptable manner continues to plague industry. Such metals as nickel, vanadium, molybdenum, cobalt, iron, and antimony present physiological and ecological challenges that are best addressed through minimization of exposure and dispersion. A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  10. Mixed cation effect in sodium aluminosilicate glasses

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.;

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural and...

  11. Sorption of alkylammonium cations on montmorillonite

    Navrátilová, Z.; Wojtowicz, P.; Vaculíková, Lenka; Šugárková, Věra


    Roč. 4, 3/147/ (2007), s. 59-65. ISSN 1214-9705 R&D Projects: GA ČR GA205/05/0871 Institutional research plan: CEZ:AV0Z30860518 Keywords : montmorillonite * adsorption * alkylammonium cations Subject RIV: CB - Analytical Chemistry, Separation

  12. Cationic flotation of some lithium ores

    The cationic flotation of some lithium ores (spodumene, amblygonite, petalite, lepidolite) is studied by the measure of zeta potential and micro-flotation tests in Hallimond tube. The effect of some modifier agents (corn starch, meta sodium silicate) on the lithium flotation is studied. (M.A.C.)

  13. Simultaneous anion and cation mobility in polypyrrole

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


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

  14. Effect of Clay Mineralogy and Exchangeable Cations on Permeability of Saudi Sandstone Reservoirs Effet de la minéralogie des argiles et des cations échangeables sur la perméabilité des réservoirs gréseux d'Arabie Saoudite

    Dahab A. S.


    Full Text Available Reservoir rocks are susceptible to formation damage during secondary recovery operations due to the particular mineralogical, textural and electrochemical properties of the clay minerals they contain. This damage can be explained by the swelling of indigeneous clays present, resulting in the constricting of pores, or by the dispersion of indigeneous nonswelling particle rearrangements during fluid flow, resulting in the plugging of the pore system, or by a combination of the two. This article describes a laboratory study showing the effect of clay mineralogy on the permeability of actual Saudi sandstone reservoirs during water flooding operations. The study shows that the permeability damage of Saudi sandstone reservoirs depends upon the amount of swelling clays and exchangeable ions as well as on the nature of these ions. Monovalent cations cause more damage than multivalent ones but within the same group of metals, those with smaller atomic mass cause more damage. Les roches réservoirs peuvent être endommagées pendant les opérations de récupération secondaire à cause des propriétés minéralogiques, texturales et électrochimiques particulières des minéraux argileux qu'elles contiennent. Cet endommagement peut s'expliquer, soit par le gonflement des argiles qui conduit à un rétrécissement des pores, soit par la migration de particules non gonflantes pendant l'écoulement des fluides qui entraîne le colmatage des milieux poreux, soit par une combinaison des deux mécanismes. Cet article présente une étude de laboratoire montrant l'effet de la minéralogie des argiles sur la perméabilité des roches réservoirs réelles d'Arabie Saoudite pendant des opérations d'injection d'eau. L'étude montre que l'endommagement de la perméabilité des roches réservoirs d'Arabie Saoudite dépend de la quantité d'argiles gonflantes et d'ions échangeables, ainsi que de la nature de ces ions. Les cations monovalents provoquent plus d

  15. Cation-cation interactions, magnetic communication and reactivity of the pentavalent uraniumion [U(NR)2]+

    Spencer, Liam P [Los Alamos National Laboratory; Schelter, Eric J [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Yang, Ping [Los Alamos National Laboratory; Gsula, Robyn L [NON LANL; Scott, Brian L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Kiplinger, Jacqueline L [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory


    The dimeric bis(imido) uranium complex [{l_brace}U(NtBu)2(I)(tBu2bpy){r_brace}2] (see picture; U green, N blue, I red) has cation-cation interactions between [U(NR)2]+ ions. This f1-f1 system also displays f orbital communication between uranium(V) centers at low temperatures, and can be oxidized to generate uranium(VI) bis(imido) complexes.

  16. Structurally Distinct Cation Channelrhodopsins from Cryptophyte Algae.

    Govorunova, Elena G; Sineshchekov, Oleg A; Spudich, John L


    Microbial rhodopsins are remarkable for the diversity of their functional mechanisms based on the same protein scaffold. A class of rhodopsins from cryptophyte algae show close sequence homology with haloarchaeal rhodopsin proton pumps rather than with previously known channelrhodopsins from chlorophyte (green) algae. In particular, both aspartate residues that occupy the positions of the chromophore Schiff base proton acceptor and donor, a hallmark of rhodopsin proton pumps, are conserved in these cryptophyte proteins. We expressed the corresponding polynucleotides in human embryonic kidney (HEK293) cells and studied electrogenic properties of the encoded proteins with whole-cell patch-clamp recording. Despite their lack of residues characteristic of the chlorophyte cation channels, these proteins are cation-conducting channelrhodopsins that carry out light-gated passive transport of Na(+) and H(+). These findings show that channel function in rhodopsins has evolved via multiple routes. PMID:27233115

  17. Radiation chemistry of aromatic dimer radical cations

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  18. Mechanism of adsorption of cations onto rocks

    Adsorption behavior of cations onto granite was investigated. The distribution coefficient (Kd) of Sr2+ and Ba2+ onto granite was determined in the solution of which pH was ranged from 3.5 to 11.3 and ionic strength was set at 10-2 and 10-1. The Kd values were found to increase with increasing pH and with deceasing ionic strength. The obtained data were successfully analyzed by applying an electrical double layer model. The optimum parameter values of the double layer electrostatics and adsorption reactions were obtained, and the mechanism of adsorption of cations onto granite was discussed. Feldspar was found to play an important role in their adsorption. (author)

  19. Planar Chiral, Ferrocene-Stabilized Silicon Cations.

    Schmidt, Ruth K; Klare, Hendrik F T; Fröhlich, Roland; Oestreich, Martin


    The preparation of a series of planar chiral, ferrocenyl-substituted hydrosilanes as precursors of ferrocene-stabilized silicon cations is described. These molecules also feature stereogenicity at the silicon atom. The generation and (29) Si NMR spectroscopic characterization of the corresponding silicon cations is reported, and problems arising from interactions of the electron-deficient silicon atom and adjacent C(sp(3) )-H bonds or aromatic π donors are discussed. These issues are overcome by tethering another substituent at the silicon atom to the ferrocene backbone. The resulting annulation also imparts conformational rigidity and steric hindrance in such a way that the central chirality at the silicon atom is set with complete diastereocontrol. These chiral Lewis acid catalysts were then tested in difficult Diels-Alder reactions, but no enantioinduction was seen. PMID:26929105

  20. Ultrafast dynamics of water in cationic micelles.

    Dokter, Adriaan M; Woutersen, Sander; Bakker, Huib J


    The effect of confinement on the dynamical properties of liquid water is investigated for water enclosed in cationic reverse micelles. The authors performed mid-infrared ultrafast pump-probe spectroscopy on the OH-stretch vibration of isotopically diluted HDO in D(2)O in cetyltrimethylammonium bromide (CTAB) reverse micelles of various sizes. The authors observe that the surfactant counterions are inhomogeneously distributed throughout the reverse micelle, and that regions of extreme salinity occur near the interfacial Stern layer. The authors find that the water molecules in the core of the micelles show similar orientational dynamics as bulk water, and that water molecules in the counterion-rich interfacial region are much less mobile. An explicit comparison is made with the dynamics of water confined in anionic sodium bis(2-ethythexyl) sulfosuccinate (AOT) reverse micelles. The authors find that interfacial water in cationic CTAB reverse micelles has a higher orientational mobility than water in anionic AOT reverse micelles. PMID:17411144

  1. Ultrafast dynamics of water in cationic micelles

    Dokter, Adriaan M.; Woutersen, Sander; Bakker, Huib J.


    The effect of confinement on the dynamical properties of liquid water is investigated for water enclosed in cationic reverse micelles. The authors performed mid-infrared ultrafast pump-probe spectroscopy on the OH-stretch vibration of isotopically diluted HDO in D2O in cetyltrimethylammonium bromide (CTAB) reverse micelles of various sizes. The authors observe that the surfactant counterions are inhomogeneously distributed throughout the reverse micelle, and that regions of extreme salinity occur near the interfacial Stern layer. The authors find that the water molecules in the core of the micelles show similar orientational dynamics as bulk water, and that water molecules in the counterion-rich interfacial region are much less mobile. An explicit comparison is made with the dynamics of water confined in anionic sodium bis(2-ethythexyl) sulfosuccinate (AOT) reverse micelles. The authors find that interfacial water in cationic CTAB reverse micelles has a higher orientational mobility than water in anionic AOT reverse micelles.

  2. Proton dynamics investigation for dimethyl ammonium cation

    Proton dynamics in dimethyl ammonium cation has been investigated by means of NMR and spin echo methods in polycrystalline salts [NH2(CH3)2]+Bi2J9- and [NH2(CH3)2]+SbJ9-. Spin-lattice relaxation time as well as second moment of NMR line have been measured for influence study of crystal structure changes on proton dynamics

  3. Alkaline earth cation extraction from acid solution

    Dietz, Mark; Horwitz, E. Philip


    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  4. Rabbit cationic protein enhances leukocyte adhesiveness.

    Oseas, R S; Allen, J; Yang, H. H.; Baehner, R. L.; Boxer, L A


    Cationic protein purified from rabbit peritoneal polymorphonuclear leukocytes (PMN) was demonstrated to incite autoaggregation of the rabbit PMN and promote adhesiveness of human PMN to endothelial cells. PMN aggregation induced by supernatants derived from secretory PMN was blocked by a specific anticationic protein antibody. These studies reveal that a positively charged protein derived from the PMN can alter surface properties of the PMN itself and imply a role for this protein in PMN immo...

  5. Limited data speaker identification

    H S Jayanna; S R Mahadeva Prasanna


    In this paper, the task of identifying the speaker using limited training and testing data is addressed. Speaker identification system is viewed as four stages namely, analysis, feature extraction, modelling and testing. The speaker identification performance depends on the techniques employed in these stages. As demonstrated by different experiments, in case of limited training and testing data condition, owing to less data, existing techniques in each stage will not provide good performance. This work demonstrates the following: multiple frame size and rate (MFSR) analysis provides improvement in the analysis stage, combination of mel frequency cepstral coefficients (MFCC), its temporal derivatives $(\\Delta,\\Delta \\Delta)$, linear prediction residual (LPR) and linear prediction residual phase (LPRP) features provides improvement in the feature extraction stage and combination of learning vector quantization (LVQ) and gaussian mixture model – universal background model (GMM–UBM) provides improvement in the modelling stage. The performance is further improved by integrating the proposed techniques at the respective stages and combining the evidences from them at the testing stage. To achieve this, we propose strength voting (SV), weighted borda count (WBC) and supporting systems (SS) as combining methods at the abstract, rank and measurement levels, respectively. Finally, the proposed hierarchical combination (HC) method integrating these three methods provides significant improvement in the performance. Based on these explorations, this work proposes a scheme for speaker identification under limited training and testing data.

  6. Low cation coordination in oxide melts

    Skinner, Lawrie [State University of New York, Stony Brook; Benmore, Chris J [Argonne National Laboratory (ANL); Du, Jincheng [University of North Texas; Weber, Richard [Argonne National Laboratory (ANL); Neuefeind, Joerg C [ORNL; Tumber, Sonia [Materials Development, Inc., Evanston, IL; Parise, John B [Stony Brook University (SUNY)


    The complete set of Faber-Ziman partial pair distribution functions for a rare earth oxide liquid were measured for the first time by combining aerodynamic levitation, neutron diffraction, high energy x-ray diffraction and isomorphic substitution using Y2 O3 and Ho2 O3 melts. The average Y- O coordination is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2 O3 (or Ho2 O3 ). Investigation of high temperature La2 O3 , ZrO2 , SiO2 , and Al2 O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation- oxygen coordination. These measurements suggest a general trend towards lower M-O coordination compared to their crystalline counterparts. It is found that this coordination number drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses.

  7. Cation-Exchange Equilibria with Fused Salts

    Solute distributions of alkali metal, alkaline- earth, transition metal, and actinide ions have been studied in fused salt-cation exchanger systems. The fused salts employed were alkali halides and nitrates. The cation exchangers used were natural zeolites, synthetic zeolites, high-porosity glasses, and molten oxide mixtures. The molten exchangers were composed of Na2O and B2O3 in various proportions. The relative quantities not only determined the exchanger capacity and electrolyte penetration but also produced distribution coefficients for a given solute which varied over several orders of magnitude. Moreover, they produced marked reversals in the selectivity series. Additional studies on the anion distributions, miscibility diagrams, vapour pressures and diffusion rates in these systems have elucidated the mechanisms involved and the relation of selectivity to solute properties, system thermodynamics, exchanger structure and available functional groups. In the region of high Na2O composition, the distribution coefficients for mono-, di- and trivalent cations in NaCl have not only the same order of selectivity found in Dowex 50-HCl systems but also similar values for the distribution coefficients. The results are summarized qualitatively and compared to behaviour in aqueous systems (Table VII). (author)

  8. An analysis of national target groups for monovalent 2009 pandemic influenza vaccine and trivalent seasonal influenza vaccines in 2009-10 and 2010-11

    Lee Esther ST


    Full Text Available Abstract Background Vaccination is generally considered to be the best primary prevention measure against influenza virus infection. Many countries encourage specific target groups of people to undertake vaccination, often with financial subsidies or a priority list. To understand differential patterns of national target groups for influenza vaccination before, during and after the 2009 influenza pandemic, we reviewed and analyzed the country-specific policies in the corresponding time periods. Methods Information on prioritized groups targeted to receive seasonal and pandemic influenza vaccines was derived from a multi-step internet search of official health department websites, press releases, media sources and academic journal articles. We assessed the frequency and consistency of targeting 20 different groups within populations which are associated with age, underlying medical conditions, role or occupations among different countries and vaccines. Information on subsidies provided to specific target groups was also extracted. Results We analyzed target groups for 33 (seasonal 2009 and 2009-10 vaccines, 72 (monovalent pandemic 2009-10 vaccine and 34 (seasonal 2010 and 2010-11 vaccines countries. In 2009-10, the elderly, those with chronic illness and health care workers were common targets for the seasonal vaccine. Comparatively, the elderly, care home residents and workers, animal contacts and close contacts were less frequently targeted to receive the pandemic vaccine. Pregnant women, obese persons, essential community workers and health care workers, however, were more commonly targeted. After the pandemic, pregnant women, obese persons, health care and care home workers, and close contacts were more commonly targeted to receive the seasonal vaccine compared to 2009-10, showing continued influence from the pandemic. Many of the countries provided free vaccines, partial subsidies, reimbursements or national health insurance coverage to

  9. [Antioxidant activity of cationic whey protein isolate].

    titova, M E; Komolov, S A; Tikhomirova, N A


    The process of lipid peroxidation (LPO) in biological membranes of cells is carried out by free radical mechanism, a feature of which is the interaction of radicals with other molecules. In this work we investigated the antioxidant activity of cationic whey protein isolate, obtained by the cation-exchange chromatography on KM-cellulose from raw cow's milk, in vitro and in vivo. In biological liquids, which are milk, blood serum, fetal fluids, contains a complex of biologically active substances with a unique multifunctional properties, and which are carrying out a protective, antimicrobial, regenerating, antioxidant, immunomodulatory, regulatory and others functions. Contents of the isolate were determined electrophoretically and by its biological activity. Cationic whey protein isolate included lactoperoxidase, lactoferrin, pancreatic RNase, lysozyme and angeogenin. The given isolate significantly has an antioxidant effect in model experimental systems in vitro and therefore may be considered as a factor that can adjust the intensity of lipid oxidation. In model solutions products of lipid oxidation were obtained by oxidation of phosphatidylcholine by hydrogen peroxide in the presence of a source of iron. The composition of the reaction mixture: 0,4 mM H2O2; 50 mcM of hemin; 2 mg/ml L-alpha-phosphatidylcholine from soybean (Sigma, German). Lipid peroxidation products were formed during the incubation of the reaction mixture for two hours at 37 degrees C. In our studies rats in the adaptation period immediately after isolation from the nest obtained from food given orally native cationic whey protein isolate at the concentration three times higher than in fresh cow's milk. On the manifestation of the antioxidant activity of cationic whey protein isolate in vivo evidence decrease of lipid peroxidation products concentration in the blood of rats from the experimental group receipt whey protein isolate in dos 0,6 mg/g for more than 20% (pwhey protein isolate has an

  10. Inorganic magnetic support for sodium cation scavenging

    Three different magnetic iron oxide-silica matrices with polyoxaalkyl units have been obtained in a multi-step synthesis. The structures of the matrices were confirmed by Fourier transform infrared spectroscopy, while their surface morphology was analyzed by scanning electron microscopy. The scavenging ability was studied by ultraviolet-visible measurements. The results demonstrate very good scavenging efficiency of compounds studied against sodium cations (Na+). The complexing abilities of the magnetic iron oxide-silica surfaces were compared with those of the previously studied analogously modified non-magnetic silica surfaces.

  11. Aggregate Formed by a Cationic Fluorescence Probe

    TIAN, Juan; SANG, Da-Yong; JI, Guo-Zhen


    The aggregation behavior of a cationic fluorescence probe 10-(4,7,10,13,16-pentaoxa-1-azacyclooctadecyl-methyl)anthracen-9-ylmethyl dodecanoate (1) was observed and studied by a fluorescence methodology in acidic and neutral conditions. By using the Py scale, differences between simple aggregates and micelles have been discussed. The stability of simple aggregates was discussed in terms of hydrophobic interaction and electrostatic repulsion. The absence of excimer emission of the anthrancene moiety of probe 1 in neutral condition was attributed to the photoinduced electron transfer mechanism instead of photodimerization.

  12. Mobility of cations in magnesium aluminate spinel

    Martinelli, J.R.; Sonder, E.; Weeks, R.A.; Zuhr, R.A.


    Transport of cations in magnesium aluminate spinel due to an applied electric field at approximately 1000 /sup 0/C has been measured by observing changes in elemental concentrations near the cathode and anode surfaces using ion backscattering techniques. The results indicate that magnesium ions are the mobile species at 1000 /sup 0/C and that these ions combine with ambient oxygen at the cathode surface to form a MgO layer. Quantitative interpretation of the data leads to the conclusion that the ionic transference number of spinel becomes approximately 0.5 after treatment in an electric field.

  13. Mobility of cations in magnesium aluminate spinel

    Transport of cations in magnesium aluminate spinel due to an applied electric field at approximately 1000 0C has been measured by observing changes in elemental concentrations near the cathode and anode surfaces using ion backscattering techniques. The results indicate that magnesium ions are the mobile species at 1000 0C and that these ions combine with ambient oxygen at the cathode surface to form a MgO layer. Quantitative interpretation of the data leads to the conclusion that the ionic transference number of spinel becomes approximately 0.5 after treatment in an electric field

  14. Mobility of cations in magnesium aluminate spinel

    Martinelli, J. R.; Sonder, E.; Weeks, R. A.; Zuhr, R. A.


    Transport of cations in magnesium aluminate spinel due to an applied electric field at approximately 1000 °C has been measured by observing changes in elemental concentrations near the cathode and anode surfaces using ion backscattering techniques. The results indicate that magnesium ions are the mobile species at 1000 °C and that these ions combine with ambient oxygen at the cathode surface to form a MgO layer. Quantitative interpretation of the data leads to the conclusion that the ionic transference number of spinel becomes approximately 0.5 after treatment in an electric field.

  15. Complex Macromolecular Architectures by Living Cationic Polymerization

    Alghamdi, Reem D.


    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  16. Cation-Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

    Mougel, Victor; Horeglad, Pawel; Nocton, Gregory; Pecaut, Jacques; Mazzanti, Marinella [CEA, INAC, SCIB, Laboratoire de Reconnaissance Ionique et Chimie de Coordination, CEA-Grenoble, 38054 GRENOBLE, Cedex 09 (France)


    Three new cation cation complexes of pentavalent uranyl, stable with respect to the disproportionation reaction, have been prepared from the reaction of the precursor [(UO{sub 2}py{sub 5})-(KI{sub 2}py{sub 2})]{sub n} (1) with the Schiff base ligands salen{sup 2-}, acacen{sup 2-}, and salophen{sup 2-} (H{sub 2}salen N, N'-ethylene-bis(salicylidene-imine), H{sub 2}acacen=-N, N'-ethylenebis(acetylacetone-imine), H{sub 2}salophen=N, N'-phenylene-bis(salicylidene-imine)). The preparation of stable complexes requires a careful choice of counter ions and reaction conditions. Notably the reaction of 1 with salophen{sup 2-} in pyridine leads to immediate disproportionation, but in the presence of [18]crown-6 ([18]C-6) a stable complex forms. The solid-state structure of the four tetra-nuclear complexes ([UO{sub 2}-(acacen)]{sub 4}[{mu}{sub 8}-]{sub 2}[K([18]C-6)(py)]{sub 2}) (3) and ([UO{sub 2}(acacen)](4)[{mu}{sub 8}-]).2[K([222])(py)] (4) ([UO{sub 2}(salophen)](4)[{mu}{sub 8}-K]{sub 2}[mu(5)-KI]{sub 2}[(K([18]C-6)]).2 [K([18]C-6)-(thf){sub 2}].2I (5), and ([UO{sub 2}(salen)(4)][{mu}{sub 8}-Rb]{sub 2}[Rb([18]C-6)]{sub 2}) (9) ([222] = [222]cryptand, py =pyridine), presenting a T-shaped cation cation interaction has been determined by X-ray crystallographic studies. NMR spectroscopic and UV/Vis studies show that the tetra-nuclear structure is maintained in pyridine solution for the salen and acacen complexes. Stable mononuclear complexes of pentavalent uranyl are also obtained by reduction of the hexavalent uranyl Schiff base complexes with cobaltocene in pyridine in the absence of coordinating cations. The reactivity of the complex [U{sup V}O{sub 2}(salen)(py)][Cp*{sub 2}Co] with different alkali ions demonstrates the crucial effect of coordinating cations on the stability of cation cation complexes. The nature of the cation plays a key role in the preparation of stable cation cation complexes. Stable tetra-nuclear complexes form in the presence of K

  17. Effect of lipid head group interactions on membrane properties and membrane-induced cationic β-hairpin folding.

    Ganesan, Sai J; Xu, Hongcheng; Matysiak, Silvina


    Stages in POPS membrane induced SVS-1 folding. One key characteristic of mIFs is the dielectric gradient and subsequently, electrostatic potential that arises from dipolar interactions in the head group region. In this work, we present a coarse-grained (CG) model for anionic and zwitterionic lipids that accounts for dipolar intricacies in the head group region. Prior work on adding dipolar interactions in a coarse grained (CG) model for peptides enabled us to achieve α/β secondary structure content de novo, without any added bias. We have now extended this idea to lipids. To mimic dipolar interactions, two dummy particles with opposite charges are added to CG polar beads. These two dummy charges represent a fluctuating dipole that introduces structural polarization into the head group region. We have used POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine) as our model lipids. We characterize structural, dynamic, and dielectric properties of our CG bilayer, along with the effect of monovalent ions. We observe head group dipoles to play a significant role in membrane dielectric gradient and lipid clustering induced by dipole-dipole interactions in POPS lipids. In addition, we studied membrane-induced peptide folding of a cationic antimicrobial peptide with anticancer activity, SVS-1. We find that membrane-induced peptide folding is driven by both (a) cooperativity in peptide self-interaction and (b) cooperativity in membrane-peptide interaction. In particular, dipolar interactions between the peptide backbone and lipid head groups contribute to stabilizing folded conformations. PMID:27165814

  18. Simultaneous Determination of Anions and Cations in Natural Water by Ion-exclusion/Cation-exchange Chromatography with a Weakly Acidic Cation-exchange Resin Column

    The simultaneous determination of anions (SO4 2-, Cl-, and NO3 -) and cations (Na+, NH4+, K+, Mg2+, and Ca2+) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cation exchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the H+-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters

  19. Simultaneous Determination of Anions and Cations in Natural Water by Ion-exclusion/Cation-exchange Chromatography with a Weakly Acidic Cation-exchange Resin Column

    Lee, Kwang Pill; Choi, Seong Ho; Park, Yu Chul; Bae, Zun Ung; Lee, Mu Sang; Lee, Sang Hak; Chang, Hye Yong [Graduate School, Kyungpook National University, Daegu (Korea, Republic of); Kwon, Se Mok [Ulsan City Health and Environmental Research Institute, Ulsan (Korea, Republic of); Tanaka, Kazuhiko [National Industrial Research Institute of Nagoya, Nagoya (Japan)


    The simultaneous determination of anions (SO{sub 4} {sup 2-}, Cl{sup -}, and NO{sub 3} {sup -}) and cations (Na{sup +}, NH{sup 4+}, K{sup +}, Mg{sup 2+}, and Ca{sup 2+}) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cation exchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the H{sup +}-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters.

  20. Cationic polymers in water treatment: Part 1: Treatability of water with cationic polymers

    Polasek, P.; Mutl, Silvestr


    Roč. 28, č. 1 (2002), s. 69-82. ISSN 0378-4738 R&D Projects: GA AV ČR KSK2067107 Keywords : cationic polymers * treatability * water quality Subject RIV: BK - Fluid Dynamics Impact factor: 0.481, year: 2002

  1. Cobalt 60 cation exchange with mexican clays

    Mexican clays can be used to remove radioactive elements from contaminated aqueous solutions. Cation exchange experiments were performed with 60 Co radioactive solution. In the present work the effect of contact time on the sorption of Co 2+ was studied. The contact time in hydrated montmorillonite was from 5 to 120 minutes and in dehydrated montmorillonite 5 to 1400 minutes. The Co 2+ uptake value was, in hydrated montmorillonite, between 0.3 to 0.85 m eq/g and in dehydrated montmorillonite, between 0.6 to 1.40 m eq/g. The experiments were done in a pH 5.1 to 5.7 and normal conditions. XRD patterns were used to characterize the samples. The crystallinity was determined by X-ray Diffraction and it was maintained before and after the cation exchange. DTA thermo grams showed the temperatures of the lost humidity and crystallization water. Finally, was observed that dehydrated montmorillonite adsorb more cobalt than hydrated montmorillonite. (Author)

  2. Cationic Antimicrobial Polymers and Their Assemblies

    Ana Maria Carmona-Ribeiro


    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  3. Photodissociation of Cerium Oxide Nanocluster Cations.

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A


    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)). PMID:27035210

  4. Ground state of naphthyl cation: Singlet or triplet?

    Dutta, Achintya Kumar; Vaval, Nayana, E-mail:; Pal, Sourav, E-mail: [Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008 (India); Manohar, Prashant U. [Department of Chemistry, BITS Pilani, Pilani Campus (India)


    We present a benchmark theoretical investigation on the electronic structure and singlet-triplet(S-T) gap of 1- and 2-naphthyl cations using the CCSD(T) method. Our calculations reveal that the ground states of both the naphthyl cations are singlet, contrary to the results obtained by DFT/B3LYP calculations reported in previous theoretical studies. However, the triplet states obtained in the two structural isomers of naphthyl cation are completely different. The triplet state in 1-naphthyl cation is (π,σ) type, whereas in 2-naphthyl cation it is (σ,σ{sup ′}) type. The S-T gaps in naphthyl cations and the relative stability ordering of the singlet and the triplet states are highly sensitive to the basis-set quality as well as level of correlation, and demand for inclusion of perturbative triples in the coupled-cluster ansatz.

  5. Bespoke cationic nano-objects via RAFT aqueous dispersion polymerisation

    Williams, M.; Penfold, NJW; Lovett, JR; Warren, NJ; Douglas, CWI; Doroshenko, N; Verstraete, P; Smets, J; Armes, SP


    A range of cationic diblock copolymer nanoparticles are synthesised via polymerisation-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerisation formulation. The cationic character of these nanoparticles can be systematically varied by utilising a binary mixture of two macro-CTAs, namely non-ionic poly(glycerol monomethacrylate) (PGMA) and cationic poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PQDMA), with poly(2-hydroxypropyl methacrylate) (PHPMA) being selected...

  6. Development of Recombinant Cationic Polymers for Gene Therapy Research

    Canine, Brenda F.; Hatefi, Arash


    Cationic polymers created through recombinant DNA technology have the potential to fill a void in the area of gene delivery. The recombinant cationic polymers to be discussed here are amino acid based polymers synthesized in E.coli with the purpose to not only address the major barriers to efficient gene delivery but offer safety, biodegradability, targetability and cost-effectiveness. This review helps the readers to get a better understanding about the evolution of recombinant cationic poly...

  7. Effect of Headgroup on DNA−Cationic Surfactant Interactions

    Dasgupta, Antara; Das, Prasanta Kumar; Dias, Rita S.; Miguel, Maria G.; Lindman, Björn; Jadhav, Vaibhav M.; Gnanamani, Muthaiah; Maiti, Souvik


    The interaction behavior of DNA with different types of hydroxylated cationic surfactants has been studied. Attention was directed to how the introduction of hydroxyl substituents at the headgroup of the cationic surfactants affects the compaction of DNA. The DNA−cationic surfactant interaction was investigated at different charge ratios by several methods like UV melting, ethidium bromide exclusion, and gel electrophoresis. Studies show that there is a discrete transition in the DNA chain fr...

  8. Bithiophene radical cation: Resonance Raman spectroscopy and molecular orbital calculations

    Grage, M.M.-L.; Keszthelyi, T.; Offersgaard, J.F.; Wilbrandt, R.


    The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution a...... the Raman spectrum excited in resonance with the absorption band at 425 nm. The spectrum was interpreted with the help of density functional theory calculations. (C) 1998 Elsevier Science B.V.......The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution and...

  9. Characterization of guinea pig myocardial leukotriene C4 binding sites. Regulation by cations and sulfhydryl-directed reagents

    Using [3H]leukotriene C4 (LTC4) and radioligand-binding techniques, specific leukotriene C4 binding sites have been identified in membranes derived from guinea pig ventricular myocardium. High performance liquid chromatography analyses indicated that, in the presence of the gamma-glutamyl transpeptidase inhibitor L-serine-borate (80 mM), less than 2% of membrane-bound [3H]LTC4 was converted at 20 degrees to [3H]leukotriene D4 or [3H]leukotriene E4. The specific binding of 4 nM [3H]LTC4, in the presence of 80 mM L-serine-borate, reached a stable steady state within 15 min at 20 degrees (pH 7.5). A monophasic Scatchard plot of saturation binding data yielded a dissociation constant (Kd) of 27.5 +/- 6.0 nM and a maximum number of binding sites (Bmax) of 19.9 +/- 5.2 pmol/mg of membrane protein. Competition binding studies of [3H]LTC4 with synthetic leukotriene C4, leukotriene D4, and leukotriene E4 and the putative peptidoleukotriene antagonists FPL 55712, SKF 88046, and 4R-hydroxy-5S-1-cysteinylglycine-6Z-nonadecanoic acid revealed an order of potency of leukotriene C4 much greater than 4R-hydroxy-5S-1-cysteinylglycine-6Z-nonadecanoic acid greater than SKF 88046 greater than LTE4 greater than LTD4 greater than FPL 55712. The specific [3H]LTC4 binding was stimulated by the divalent cations Ca2+, Mg2+, and Mn2+ and to a lesser degree by the monovalent cations Na+, K+, Li+, and NH4+. CaCl2 (3 mM) and NaCl (150 mM) stimulated the LTC4 binding by increasing the Bmax to 42.6 +/- 5.9 and 35.0 +/- 2.0 pmol/mg, respectively, but had minimal effects on Kd

  10. Interaction of actinide cations with synthetic polyelectrolytes

    The binding of Am+3, Th+4 and UO2+2 to polymaleic acid, polyethylenemaleic acid and polymethylvinylethermaleic acid has been measured by a solvent extraction technique at 250C and either 0.02 or 0.10 M ionic strength. The solutions were buffered over a pH range such that the percent of carboxylate groups ionized ranged from 25 to 74%. The binding was described by two constants, β1 and β2, which were evaluated after correction for complexation of the actinide cations by acetate and hydrolysis. For comparable degrees of ionization, all three polyelectrolytes showed similar binding strengths. In general, these results indicated that the binding of actinides to these synthetic polyelectrolytes is basically similar to that of natural polyelectrolytes such as humic and fulvic acids. (orig.)

  11. Hydration Structure of the Quaternary Ammonium Cations

    Babiaczyk, Wojtek Iwo


    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  12. Univalent-cation-elicited acidification by yeasts.

    Kotyk, A; Georghiou, G


    Addition of univalent cations to sugar-metabolizing Saccharomyces cerevisiae, Schizosaccharomyces pombe and Lodderomyces elongisporus brought about a powerful acidification of the external medium with rates up to nearly 20 nmol H+ per min per mg dry wt. in S. cerevisiae, over 15 nmol in S. pombe, and 4.7 nmol in L. elongisporus. These rates were as much as 20 times, 5.5 times and 10.3 times, respectively. higher than in the absence of K+. Use of galactose-induced cells, of H(+)-ATPase-deficient mutants and observations over the entire growth curve indicated that the K+ effect on H+ extrusion is not connected with the H(+)-ATPase function as such but rather depends on metabolic reactions producing ATP. The effect has apparently nothing to do with the electrical potential across the plasma membrane. PMID:7804140

  13. Cationic nanofibrillar cellulose with high antibacterial properties.

    Chaker, Achraf; Boufi, Sami


    Cationic nanofibrillar cellulose (C-NFC) has been prepared via a high pressure homogenization using quaternized cellulose fibers with glycidyltrimethylammonium chloride. It has been shown that the quaternization of dried softwood pulp facilitated the defibrillation processes and prevented clogging of the homogenizer. The effects of the trimethylammonium chloride content on the fibrillation yield, the transparency degree of the gel, the rheological behavior of the NFC suspension and their electrokinetic properties were investigated. AFM observation showed that the NFC suspension consisted of individualized cellulose I nanofibrils 4-5nm in width and length in the micronic scale. In addition to their strong reinforcing potential, the inclusion of C-NFC into a polymer matrix was shown to efficiently enhance the antibacterial activity. The reinforcing potential of C-NFC, studied by dynamic mechanical analysis (DMA), was compared to anionic NFC and the difference was explained in terms of the nanofibrils capacities to build up a strong networks held by hydrogen bonding. PMID:26256179

  14. Electronic structure near cationic defects in magnetite

    We used the DFT + U method to describe the modification of the physical properties induced by cationic point defects in cubic magnetite Fe3O4. We considered the case of Fe vacancies and interstitial atoms in non-stoichiometric magnetite, and of Frenkel defects in a stoichiometric crystal. For each of these defects, we give results on the modification of the magnetic moment of atoms near the defect. We describe the local reorganization of the electric charge which is responsible for changes in the average oxidation degree of Fe atoms. We show that gap states, when they exist, do not destroy the half-metallic character of magnetite. Fe defects, however, change the filling of bands crossing the Fermi level and must be mostly responsible for a decrease in the magnetization. (paper)

  15. Molecular machines: stimulation of cation motion in molecular switches

    The theoretical aspects of the mechanism of the motion of cations and ligands in molecular machines referred to as redox switches are presented. The interrelated properties of cations - the energetic, electrochemical, spectral, and magnetic properties; their propensity to form either covalent or ionic bonds; and the relative softness and hardness of cations and ligands - stimulate molecular motion. These properties determine the thermal stability and stability to destruction caused by electrochemical processes and, eventually, the maximal number of transformation cycles. The maximal efficiency of redox switches is attained when the redox reaction involves a cation with a half-filled (d5, f7) or complete (d10, f14) electronic shell. The role of the Jahn-Teller effect is considered: it is responsible for geometry distortion, which stimulates cation motion. The properties of nd- and 4f-block cations are compared from the standpoint of their use for designing redox switches. In switches constructed on the basis of supramolecular compounds containing hard and soft moieties, softer cations (Fe2+, Co2+, Cu+, etc.) prefer to coordinate to soft ligands and harder cations (Fe3+, Co3+, Cu2+, etc.) prefer to coordinate to hard ligands. A cation moves due to the soft-hard change of its coordination sphere in the course of the redox reaction. Design of redox switches based on solid compounds with a cation in mixed oxidation state is shown to be promising. Cations can change their oxidation state with a change in temperature or pressure. The possibility of designing magnetic switches is considered

  16. Polyenyl cations and radical cations – synthesis, spectroscopic properties and reactions

    Kildahl-Andersen, Geir


    In the present work, polyene precursors for the formation of charged polyenyl species were synthesised. Their conversion to charge delocalised radical cations and diamagnetic mono- and dications was carried out by treatment with Brønsted and Lewis acids. Reaction conditions were optimised to achieve sufficient stability of the charged polyenes for characterisation by modern spectroscopic methods; in particular nearinfrared absorption spectroscopy (NIR), two-dimensional nuclear magnetic resona...

  17. Effects of cationic hydroxyethyl cellulose on glucose tolerance and obesity

    Cholestyramine is a cationic polymer prescribed to lower cholesterol in humans. We investigated the effects of cationic hydroxyethyl cellulose (cHEC) on weight loss and metabolic disorders associated with obesity using both hamster and diet-induced obese mouse models. Golden Syrian hamsters and ob...

  18. Photodynamic Inactivation of Bacteria and Biofilms Using Cationic Bacteriochlorins

    Meerovich, G. A.; Tiganova, I. G.; Makarova, E. A.; Meerovich, I. G.; Romanova Ju., M.; Tolordova, E. R.; Alekseeva, N. V.; Stepanova, T. V.; Yu, Koloskova; Luk'anets, E. A.; Krivospitskaya, N. V.; Sipailo, I. P.; Baikova, T. V.; Loschenov, V. B.; Gonchukov, S. A.


    This work is devoted to the study of two new synthetic bacteriochlorins with four and eight cationic substitutes as the photosensitizers in the photodynamic process. The spectral and antibacterial properties of these photosensitizers in saline solution were investigated. It is shown, that the aggregation ability decreases and the antibacterial efficiency grows as the cationic substitute number increases.

  19. Decomplexing metallic cations from metallo-organic compounds

    Melian, C.I.; Kapteijn F.; Moulijn, J.A.


    The invention is directed to a process for liberating metallic cations from metallo-organic compounds, said process comprising contacting an aqueous solution of the metallo-organic compound with an oxidising agent, thereby oxidising the organic component and obtaining the free cation

  20. Effects of metallic cations in the beryl flotation

    The beryl zeta potential in microelectrophoretic cell is studied in the presence of neutral electrolyte, cations of calcium, magnesium and iron. The petroleum sulfonate is used how collector in Hallimond tube. Hydroxy complex of metallic cations seems activate the ore and precipitates of colloidal metallic hidroxies seems lower him when added to the mixture. (M.A.C.)

  1. Stable polyfluorinated cycloalkenyl cations and their NMR spectra

    New stable 1-methoxyperfluoro-2-ethylcyclobutenyl, 1-methoxyperfluoro-2-methylcyclo-pentenyl, and 1-methoxyperfluoro-2-ethylcyclohexenyl cations were obtained by the action of antimony pentafluoride on the corresponding olefins. The distribution of the charges in the investigated polyfluorinated cycloalkenyl cations was investigated by 13C NMR method

  2. In vivo toxicity of cationic micelles and liposomes

    Knudsen, Kristina Bram; Northeved, Helle; Ek, Pramod Kumar;


    This study investigated toxicity of nanocarriers comprised of cationic polymer and lipid components often used in gene and drug delivery, formulated as cationic micelles and liposomes. Rats were injected intravenously with 10, 25 or 100 mg/kg and sacrificed after 24 or 48 h, or 24 h after the las...

  3. Gas-operated heat pump for monovalent space heating and tap water heating. A seizable contribution to carbon dioxide emission control; Gasbetriebene Waermepumpe zur monovalenten Raumbeheizung und Trinkwassererwaermung. Ein greifbarer Beitrag zur Reduktion der CO{sub 2}-Emissionen

    Heikrodt, K.; Heckt, R. [Viessmann Werke GmbH und Co., Allendorf (Germany)


    The project had the objectives to develop a Vuilleumier heat pump for space heating and make an experimental study testing it as a heat generator for a heating system for one- and multi-family houses. Apart from monovalent operation, the following boundary conditions were defined: provision for connection to existing heating systems, even radiator heatings with 75 C/60 C, tap water heating, and air-source heat. Performance constant, manufacturing cost, freedom from maintenance, and service life were taken into consideration in the design, rating and construction of the unit. (orig.) [German] Ziel des Vorhabens war die Entwicklung einer Vuilleumier-Waermepumpe zur Raumbeheizung und deren experimentelle Untersuchung als Waermeerzeuger fuer ein Heizungssystem in Ein- und Mehrfamilienhaeusern. Als Rahmebedingungen wurden neben einer monovalenten Betriebsweise auch die moegliche Anbindung an bestehende Heizungssysteme, sogar Radiatorheizungen mit 75 C/60 C, Trinkwassererwaermung und Luft als Waermequelle festgelegt. Leistungszahl, Herstellkosten, Wartungsfreiheit und Lebensdauer wurden in Konzeption, Auslegung und Konstruktion beruecksichtigt. (orig.)

  4. Forces between silica particles in the presence of multivalent cations.

    Valmacco, Valentina; Elzbieciak-Wodka, Magdalena; Herman, David; Trefalt, Gregor; Maroni, Plinio; Borkovec, Michal


    Forces between negatively charged silica particles in aqueous electrolyte solutions were measured with the colloidal probe technique based on the atomic force microscope (AFM). The present study focuses on the comparison of monovalent and multivalent counterions, namely K(+), Mg(2+), and La(3+). The force profiles can be well described with the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO) down to distances of about 4nm. At smaller distances, the forces become strongly repulsive due to additional non-DLVO repulsion. In the presence of La(3+), one observes an additional attractive force with a range of about 1nm at intermediate salt concentrations. This force is probably related to ion-ion correlations, but could also be influenced by surface charge heterogeneities or charge fluctuation forces. PMID:27016916

  5. Do Cation-π Interactions Exist in Bacteriorhodopsin

    HU Kun-Sheng; WANG Guang-Yu; HE Jin-An


    Metal ions are essential to the structure and physiological functions of bacteriorhodopsin. Experimental evidence suggests the existence of specific cation binding to the negatively charged groups of Asp85 and Asp212 via an electrostatic interaction. However, only using electrostatic force is not enough to explain the role of the metal cations because the carboxylate of Asp85 is well known to be protonated in the M intermediate. Considering the presence of some aromatic amino acid residues in the vicinity of the retinal pocket, the existence of cation-π interactions between the metal cation and aromatic amino acid residues is suggested. Obviously, introduction of this kind of interaction is conducive to understanding the effects of the metal cations and aromatic amino acid residues inside the protein on the structural stability and proton pumping of bacteriorhodopsin.

  6. Promotion of radiation-induced cationic polymerization by onium salts

    The radiation-induced cationic polymerization of styrene derivatives was studied in the presence of diphenyliodonium and triphenylsulfonium hexafluorophosphates in dichloromethane. A remarkable promotion of the polymerization was observed in the presence of the salts. The pulse radiolysis study revealed that the promotion of the polymerization is due to the ion-pair formation between the initiating cations and the nonnucleophilic complex metal halide anions of the salts resulting in the stabilization of the cations toward neutralization. An additional effect observed in the case of diphenyliodonium salt is the oxidation of free radical species to the cations responsible for the polymerization. An increase in molecular weight at low temperature suggested that the propagating cations are also paired with the counterions derived from the salts. (author)

  7. The lack of age-pigments and the alterations in intracellular monovalent electrolytes in spontaneously hypertensive, stroke-prone (SHRsp) rats as revealed by electron microscopy and X-ray microanalysis

    Male, spontaneously hypertensive, stroke-prone (SHRsp) rats established by Okamoto et al. were studied. About 80% of the males of this strain have a particularly short life span (33-41 weeks); they display a considerable hypertension (above 220 mmHg) and a tendency for plurifocal brain strokes. Hypertension and strokes can be provoked in an accelerated and synchronized fashion by supplementing 1% NaCl into their drinking water. Symptoms of the appearance of brain strokes can be judged from characteristic signs of motor disorders, and can be established also by pathohistology. Since hypertension and arteriosclerosis are frequently involved in aging, the question we intended to answer was whether these animals may represent a model of the normal aging process or not. Two approaches are described: (1) Accumulation of lipofuscin granules in their brain, liver and myocardium was followed by transmission electron microscopy before and after the appearance of strokes. It has been established that these tissues do not show any typical accumulation of lipofuscin granules, although submicroscopic signs of an enhanced damage of cell organelles (especially of mitochondria in liver and brain cells, but not in myocardium) were encountered. (2) The intracellular monovalent composition in the brain and liver was measured by using bulk-specimen X-ray microanalysis. The intracellular Na-content (mEq/kg water) was significantly higher (170-200%) in both the brain and liver cells, whereas the K-content increased only moderately (118-130%). The results suggest that although the SHRsp rats do not represent a direct model for the normal aging process from the point of view of lipofuscin accumulation, the shifts of the monovalent electrolyte contents in the brain and liver cells observed already in the youngest ages, are similar to those observed in aged normal rats

  8. Therapeutic potential of cationic steroid antibacterials.

    Salmi, Chanaz; Brunel, Jean M


    Antibiotics were one of the great health successes of the 20th century. Antibiotics, both naturally derived and synthetic, have resulted in huge decreases in both morbidity and mortality from bacterial infections. As a consequence, the 'antibiotic age' has changed public expectations about the results of infectious disease. However, this has led to high levels of inappropriate prescribing, where antibiotics may be administered to fulfil patient expectations rather than for clinical benefit. Along with unwise uses in agriculture and elsewhere, this has contributed to recent rises in numbers of antibiotic-resistant bacteria. As a result, many commentators have described this as the end of the antibiotic age and the term 'superbug' has entered the common vocabulary for multi-drug-resistant bacteria such as vancomycin-resistant Enterococcus, multi-drug-resistant Staphylococcus aureus and multi-drug-resistant Pseudomonas aeruginosa. In this context, an attractive approach for the development of antibacterial agents is the use of a new class of cationic steroidal compounds mimicking polymyxin activities. The permeabilization properties of these agents of the outer membranes of Gram-negative bacteria are reported in this review, as well as a discussion of literature results. PMID:17685865


    Elina Orblin


    Full Text Available Papermaking pulps are a mixture of fibres, fibre fragments, and small cells (parenchyma or ray cells, usually called pulp fines. The interactions between pulp fines and a cationic copolymer of acrylamide and acryloxyethyltrimethyl ammonium chloride were investigated based on solid-liquid isotherms prepared under different turbulence, and subsequent advanced surface characterization using X-ray photoelectron spectroscopy (XPS and time-of-flight secondary ion mass spectrometry (ToF-SIMS. The surface charge and surface area of pulp fine substrates were measured by methylene blue sorption-XPS analysis and nitrogen adsorption combined with mercury porosimetry, respectively. The driving force behind polyelectrolyte adsorption was the amount of the surface anionic charge, whereas surface area appeared to be of less importance. Based on a comparison of solid-liquid and XPS sorption isotherms, different polyelectrolyte conformations were suggested, depending on the types of fines: A flatter conformation and partial cell-wall penetration of polyelectrolytes on kraft fines from freshly prepared pulp, and a more free conformation with extended loops and tails on lignocellulosic fines from recycled pulp. Additionally, ToF-SIMS imaging proved that recycled pulp fines contained residual de-inking chemicals (primarily palmitic acid salts that possibly hinder the electrostatic interactions with polyelectrolytes.

  10. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment.

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C; Anand, Atul; Cederkvist, Luise; Petersen, Nikolaj H T; Nylandsted, Jesper; Stenvang, Jan; Mellemgaard, Anders; Østerlind, Kell; Friis, Søren; Jäättelä, Marja


    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any non-localized cancer, and ebastine use showed a similar tendency. The association between CAD antihistamine use and reduced mortality was stronger among patients with records of concurrent chemotherapy than among those without such records. In line with this, sub-micromolar concentrations of loratadine, astemizole and ebastine sensitized NSCLC cells to chemotherapy and reverted multidrug resistance in NSCLC, breast and prostate cancer cells. Thus, CAD antihistamines may improve the efficacy of cancer chemotherapy. PMID:27333030

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

    Andreeva, Nadezhda A.; Chaban, Vitaly V.


    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.

  12. Cationic Nanoparticles Induce Nanoscale Disruption in Living Cell Plasma Membranes

    Chen, Jiumei; Hessler, Jessica A.; Putchakayala, Krishna; Panama, Brian K.; Khan, Damian P.; Hong, Seungpyo; Mullen, Douglas G.; DiMaggio, Stassi C.; Som, Abhigyan; Tew, Gregory N.; Lopatin, Anatoli N.; Baker, James R.; Banaszak Holl, Mark M.; Orr, Bradford G


    It has long been recognized that cationic nanoparticles induce cell membrane permeability. Recently, it has been found that cationic nanoparticles induce the formation and/or growth of nanoscale holes in supported lipid bilayers. In this paper we show that non-cytotoxic concentrations of cationic nanoparticles induce 30–2000 pA currents in 293A and KB cells, consistent with a nanoscale defect such as a single hole or group of holes in the cell membrane ranging from 1 to 350 nm2 in total area....

  13. Competitive Solvation of the Imidazolium Cation by Water and Methanol

    Chaban, Vitaly


    Imidazolium-based ionic liquids are widely used in conjunction with molecular liquids for various applications. Solvation, miscibility and similar properties are of fundamental importance for successful implementation of theoretical schemes. This work reports competitive solvation of the 1,3-dimethylimidazolium cation by water and methanol. Employing molecular dynamics simulations powered by semiempirical Hamiltonian (electronic structure level of description), the local structure nearly imidazolium cation is described in terms of radial distribution functions. Although water and methanol are chemically similar, water appears systematically more successful in solvating the 1,3-dimethylimidazolium cation. This result fosters construction of future applications of the ternary ion-molecular systems.

  14. Evaluation of phenomena affecting diffusion of cations in compacted bentonite

    In a number of diffusion studies, contradictions between the apparent diffusivities of cations and their distribution coefficients in bentonite have been found. Two principal reasons have been offered as explanations for this discrepancy; diffusion of the sorbed cations, often called surface diffusion, and the decrease of sorption in compacted clay compared to a sorption value obtained from a batch experiment. In the study the information available from the literature on sorption-diffusion mechanisms of cations in bentonite has been compiled and re-interpreted in order to improve the understanding of the diffusion process. (103 refs., 23 figs., 8 tabs.)

  15. Isomerization of propargyl cation to cyclopropenyl cation: Mechanistic elucidations and effects of lone pair donors

    Zodinpuia Pachuau; Kiew S Kharnaior; R H Duncan Lyngdoh


    This ab initio study examines two pathways (one concerted and the other two-step) for isomerization of the linear propargyl cation to the aromatic cyclopropenyl cation, also probing the phenomenon of solvation of this reaction by simple lone pair donors (NH3, H2O, H2S and HF) which bind to the substrate at two sites. Fully optimized geometries at the B3LYP/6-31G(d) level were used, along with single point QCISD(T)/6-311+G(d,p) and accurate G3 level calculations upon the DFT optimized geometries. For the unsolvated reaction, the two-step second pathway is energetically favoured over the one-step first pathway. Lone pair donor affinity for the various C3H$^{+}_{3}$ species follows the uniform order NH3 > H2S>H2O>HF. The activation barriers for the solvated isomerizations decrease in the order HF>H2O>H2S>NH3 for both pathways. The number of lone pairs on the donor heteroatom as well as the heteroatom electronegativity are factors related to both these trends. Compared to the unsolvated cases, the solvated reactions have transition states which are usually ‘later’ in position along the reaction coordinate, validating the Hammond postulate.

  16. Chemical bonding and structural ordering of cations in silicate glasses

    The specific surrounding of cations in multicomponent silicate glasses is briefly presented. Information about interatomic distances and site geometry may be gained by using spectroscopic methods among which x-ray absorption spectroscopy may be used for the largest number of glass components. Scattering of x-rays and neutrons may also be used to determine the importance of medium range order around specific cations. All the existing data show that cations occur in sites with a well-defined geometry, which are in most cases connected to the silicate polymeric network. Medium range order has been detected around cations such as Ti, Ca and Ni, indicating that these elements have an heterogeneous distribution within the glassy matrix. (authors)


    Klein, Petr; Dědeček, Jiří; Sklenák, Štěpán; Thomas, Haunani M.

    Segovia: CIS-5, 2013. s. 1. [Czech-Italian- Spanish Conference on Molecular Sieves and Catalysis /5./. 16.06.2013-19.06.2013, Segovia] Institutional support: RVO:61388955 Keywords : lithium cations * crystallography Subject RIV: CF - Physical ; Theoretical Chemistry

  18. Infrared spectroscopy of mass-selected metal carbonyl cations

    Ricks, A. M.; Reed, Z. E.; Duncan, M. A.


    Metal carbonyl cations of the form M(CO)n+ are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding rare gas atom "tagged" analogs, M(CO)n(RG)m+, are studied with mass-selected infrared photodissociation spectroscopy in the carbonyl stretching region and with density functional theory computations. The number of infrared-active bands, their frequency positions, and their relative intensities provide distinctive patterns allowing determination of the geometries and electronic structures of these complexes. Cobalt penta carbonyl and manganese hexacarbonyl cations are compared to isoelectronic iron pentacarbonyl and chromium hexacarbonyl neutrals. Gold and copper provide examples of "non-classical" carbonyls. Seven-coordinate carbonyls are explored for the vanadium group metal cations (V +, Nb + and Ta +), while uranium cations provide an example of an eight-coordinate carbonyl.

  19. Study on cationic photopolymerization reaction of epoxy polysiloxane

    Sun, F.; Jiang, S. L.; Liu, J.


    The effects of epoxy monomers, concentration of photoinitiator and radical photoinitiators on the photosensitive properties of cationic phopolymerization system with a novel epoxy polysiloxane oligomer (CEPS) were investigated via a gel yield method. The results showed that among the tested epoxy monomers, the reactivity of ERL-4221 with cycloaliphatic epoxy groups was the highest. The optimum concentration of diaryldiodonium salt (SR-1012) was determined as 4-5 wt.%. Increasing the amounts of ERL-4221 in the CEPS cationic photopolymerization system, UV-curing rate increased. Radical photoinitiators with ArC dbnd O structure possessed sensitization capacity to the cationic photoinitiator SR-1012. The photosensitivity of the CEPS system could be up to 165 mJ/cm 2. Adding a small amount of IPA and BP could greatly improve the photosensitivity of CEPS cationic photosensitive system. The optimal quantity of isopropanol added to the system was not more than 2 wt.%.

  20. Cation antisite disorder in uranium-doped gadolinium zirconate pyrochlores

    The incorporation of uranium into gadolinium zirconate (Gd2Zr2O7) is investigated by synchrotron X-ray powder diffraction and X-ray absorption near-edge structure (XANES) spectroscopy. The results suggest that the uranium cation is largely located on the pyrochlore B-site instead of the targeted A-site. Cation disorder in Gd2Zr2O7 and U-doped Gd2Zr2O7 is investigated by positron annihilation lifetime spectroscopy (PALS) which demonstrates the absence of cation vacancies in these systems. This work provides direct evidence for cation antisite (A- and B-site mixing) disorder in U-doped and off-stoichiometric Gd2Zr2O7 pyrochlore

  1. Study on cationic photopolymerization reaction of epoxy polysiloxane

    The effects of epoxy monomers, concentration of photoinitiator and radical photoinitiators on the photosensitive properties of cationic phopolymerization system with a novel epoxy polysiloxane oligomer (CEPS) were investigated via a gel yield method. The results showed that among the tested epoxy monomers, the reactivity of ERL-4221 with cycloaliphatic epoxy groups was the highest. The optimum concentration of diaryldiodonium salt (SR-1012) was determined as 4-5 wt.%. Increasing the amounts of ERL-4221 in the CEPS cationic photopolymerization system, UV-curing rate increased. Radical photoinitiators with ArC=O structure possessed sensitization capacity to the cationic photoinitiator SR-1012. The photosensitivity of the CEPS system could be up to 165 mJ/cm2. Adding a small amount of IPA and BP could greatly improve the photosensitivity of CEPS cationic photosensitive system. The optimal quantity of isopropanol added to the system was not more than 2 wt.%

  2. Degradation Mechanism of Cationic Red X-GRL by Ozonation

    Wei Rong ZHAO; Xin Hua XU; Hui Xiang SHI; Da Hui WANG


    The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.

  3. Investigation of Fragmentation of Tryptophan Nitrogen Radical Cation

    Piatkivskyi, Andrii; Happ, Marshall; Lau, Justin Kai-Chi; Siu, K. W. Michael; Hopkinson, Alan C.; Ryzhov, Victor


    This work describes investigation of the fragmentation mechanism of tryptophan N-indolyl radical cation, H3N+-TrpN• ( m/ z 204) studied via DFT calculations and several gas-phase experimental techniques. The main fragment ion at m/ z 131, shown to be a mixture of up to four isomers including 3-methylindole (3MI) π-radical cation, was found to undergo further loss of an H atom to yield one of the two isomeric m/ z 130 ions. 3-Methylindole radical cation generated independently (via CID of [CuII(terpy)3MI]•2+) displayed gas-phase reactivity partially similar to that of the m/ z 131 fragment, further confirming our proposed mechanism. CID of deuterated tryptophan N-indolyl radical cation ( m/ z 208) suggested that up to six H atoms are involved in the pathway to formation of the m/ z 131 ion, consistent with hydrogen atom scrambling during CID of protonated Trp.

  4. Sulfometuron incorporation in cationic micelles adsorbed on montmorillonite

    Mishael, Y. G.; Undabeytia López, Tomás; Rytwo, Giora; Papahadjopoulos Sternberg, B.; Rubin, Baruch; Nir, Shlomo


    The aim of this study was to understand the interactions between alkylammonium cations present as monomers and micelles and a clay mineral, montmorillonite, to develop slow release formulations of anionic herbicides, such as sulfometuron (SFM) whose leaching in soils is an environmental and economic problem. In the proposed formulation the herbicide is incorporated in positively charged micelles of quaternary amine cations, which in turn adsorb on the negatively charged clay. The adsorption o...

  5. Microscopic Theory of Cation Exchange in CdSe Nanocrystals

    Ott, Florian D.; Spiegel, Leo L.; Norris, David J.; Erwin, Steven C.


    Although poorly understood, cation-exchange reactions are increasingly used to dope or transform colloidal semiconductor nanocrystals (quantum dots). We used density-functional theory and kinetic Monte Carlo simulations to develop a microscopic theory that explains structural, optical, and electronic changes observed experimentally in Ag-cation-exchanged CdSe nanocrystals. We find that Coulomb interactions, both between ionized impurities and with the polarized nanocrystal surface, play a key...

  6. Bithiophene radical cation: Resonance Raman spectroscopy and molecular orbital calculations

    Grage, M.M.-L.; Keszthelyi, T.; Offersgaard, J.F.;


    The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution a...... the Raman spectrum excited in resonance with the absorption band at 425 nm. The spectrum was interpreted with the help of density functional theory calculations. (C) 1998 Elsevier Science B.V....

  7. Migration of Cations and Anions in Amorphous Polymer Electrolytes

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


    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...

  8. Mercury release from deforested soils triggered by base cation enrichment.

    Farella, N; Lucotte, M; Davidson, R; Daigle, S


    The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide. PMID:16781764

  9. Complexation Between Cationic Diblock Copolymers and Plasmid DNA

    Jung, Seyoung; Reineke, Theresa; Lodge, Timothy

    Deoxyribonucleic acids (DNA), as polyanions, can spontaneously bind with polycations to form polyelectrolyte complexes. When the polycation is a diblock copolymer with one cationic block and one uncharged hydrophilic block, the polyelectrolyte complexes formed with plasmid DNA (pDNA) are often colloidally stable, and show great promise in the field of polymeric gene therapy. While the resulting properties (size, stability, and toxicity to biological systems) of the complexes have been studied for numerous cationic diblocks, the fundamentals of the pDNA-diblock binding process have not been extensively investigated. Herein, we report how the cationic block content of a diblock influences the pDNA-diblock interactions. pDNA with 7164 base pairs and poly(2-deoxy-2-methacrylamido glucopyranose)-block-poly(N-(2-aminoethyl) methacrylamide) (PMAG-b-PAEMA) are used as the model pDNA and cationic diblock, respectively. To vary the cationic block content, two PMAG-b-PAEMA copolymers with similar PMAG block lengths but distinct PAEMA block lengths and a PAEMA homopolymer are utilized. We show that the enthalpy change from pDNA-diblock interactions is dependent on the cationic diblock composition, and is closely associated with both the binding strength and the pDNA tertiary structure.

  10. A comparison between three methods for the determination of cation exchange capacity and exchangeable cations in soils

    Ciesielski, H.; Sterckeman, T.


    The object of this study is to compare the results obtained with three standardized methods of determination of cationic exchange capacity (CEC) and exchangeable cations (Ca, Mg, K) in soils. The three methods are based on different exchange reagents: cobalt hexamine (Cohex) trichloride, barium chloride and ammonium acetate. Exchange procedures are different as well; they are, respectively, single extraction, successive extractions and percolation. Values measured with barium and Cohex as ind...

  11. A clinical trial to assess the immunogenicity and safety of Inactivated Influenza Vaccine (Whole Virion IP (Pandemic Influenza (H1N1 2009 Monovalent Vaccine; VaxiFlu-S ™ in healthy Indian adult population

    A H Kubavat


    Full Text Available Background : The pandemic of H1N1 2009 influenza has spread world over and low degree of virus transmission has continued in several regions of India. Aims : To assess the immunogenicity and safety of Pandemic Influenza (H1N1 2009 Monovalent Vaccine in healthy adult Indian population. Settings and Design : Prospective, open label, multicentric, phase 2/3 clinical trial. Materials and Methods : Healthy adult Indian subjects belonging to either 18-59 years or ≥60 years age groups were enrolled and administered a single 0.5 ml (≥15 mcg of hemagglutinin antigen dose of vaccine in the deltoid muscle. Anti-hemagglutinin antibody titer was assessed at baseline and 21 (±2 days after vaccination by Hemagglutination Inhibition (HI test. Safety assessments were done for a period of 42 days. Statistical Analysis Used : Percentages of appropriate population with 95% confidence intervals calculated, log transformation of the data to calculate Geometric Mean Titers (GMTs and chi-square test and student′s t-test applied for significance testing. Results : 182/198 and 53/63 volunteers in age groups of 18-59 years and ≥60 years, respectively, achieved an HI titer ≥1 : 40 at Day 21 (91.9% [95% confidence interval: 88.1-95.7%] and 84.1% [75.1-93.2%]; P=0.072. Further, 171/198 and 50/63 volunteers in the respective age groups achieved seroconversion/four-fold increase in titer at Day 21 (86.4% [81.6-91.1%] and 79.4% [69.4-89.4%]; P=0.179. A significant rise of 22.6-fold [18.0-28.4] and 10.5-fold [7.4-15.0] was noted in GMT in the respective age groups (P<0.001 for both groups as compared to baseline. Nine vaccine-related adverse events were reported (3.4% incidence [1.2-5.6%], which were of low severity only. Conclusions : Pandemic Influenza (H1N1 2009 Monovalent Vaccine produces excellent immunogenic response with a good tolerability profile in adult Indian population.

  12. Cation Uptake and Allocation by Red Pine Seedlings under Cation-Nutrient Stress in a Column Growth Experiment

    Shi, Zhenqing; Balogh-Brunstad, Zsuzsanna; Grant, Michael R.; Harsh, James B.; Gill, Richard; Thomashow, Linda; Dohnalkova, Alice; Stacks, Daryl; Letourneau, Melissa; Keller, Chester K.


    Background and Aims Plant nutrient uptake is affected by environmental stress, but how plants respond to cation-nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient limitation on cation uptake in an experimental plant-mineral system. Methods Column experiments, with red pine (Pinus resinosa Ait.) seedlings growing in sand/mineral mixtures, were conducted for up to nine months under a range of Ca- and K-limited conditions. The Ca and K were supplied from both minerals and nutrient solutions with varying Ca and K concentrations. Results Cation nutrient stress had little impact on carbon allocation after nine months of plant growth and K was the limiting nutrient for biomass production. The Ca/Sr and K/Rb ratio results allowed independent estimation of dissolution incongruency and discrimination against Sr and Rb during cation uptake processes. The fraction of K in biomass from biotite increased with decreasing K supply from nutrient solutions. The mineral anorthite was consistently the major source of Ca, regardless of nutrient treatment. Conclusions Red pine seedlings exploited more mineral K in response to more severe K deficiency. This did not occur for Ca. Plant discrimination factors must be carefully considered to accurately identify nutrient sources using cation tracers.

  13. Radiolytically generated cation radicals and their intramolecular transformations

    Recent theoretical and experimental results indicate that conventional cation radicals derived directly from their neutral precursors are often less stable than their nonconventional isomers with no stable counterparts. Many organic cation radicals may spontaneously isomerise, often by a single intramolecular hydrogen transfer, to more stable distonic forms characterised by spatially separated charge and radical side. Cation radicals radiolytically generated in Freon matrices were investigated using low temperature EPR spectroscopy and DFT quantum chemical calculations, which helped to assign the observed transients and to explain the underlying transformations. Different types of transformations of the cation radicals were comprehensively studied. The primary cation radicals of the 2,5-dihydrofuran (2,5-DHF) and 2,5-dihydropyrrol (2,5-DHP) are not stable and undergo irreversible transformation to 2,4-DHF.+ or 2,4-DHP.+, respectively, by intramolecular H-shift within the molecular ring to the former double bond. The 2,4-DHF.+ and 2,4-DHP.+ are stable only at a small temperature range and undergo further intramolecular rearrangements through 2→3 and 3→4 H-shifts, which can be induced by illumination with visible light. In case of lactone cation radicals intramolecular H-transfer occurs from the methylene group in α-position to the primary radical centre localized on carbonyl oxygen. The stability of the primary species depends on geometrical parameters of the lactones studied. The cation radicals of 5-membered ring lactones are most stable, due to the largest separation between the H-atom on the ring and the carbonyl oxygen and, as follows, the largest activation energy. The formation of two new cyclic species was observed in the case of the cation radical of ethyl acrylate (EA), in a reaction sequence of hydrogen transfer from the ester group to the carbonyl oxygen and subsequent intramolecular cycloaddition of the terminal radical to the vinyl double bond

  14. Electrophysiological characterization of human and mouse sodium-dependent citrate transporters (NaCT/SLC13A5) reveal species differences with respect to substrate sensitivity and cation dependence.

    Zwart, Ruud; Peeva, Polina M; Rong, James X; Sher, Emanuele


    The citric acid cycle intermediate citrate plays a crucial role in metabolic processes such as fatty acid synthesis, glucose metabolism, and β-oxidation. Citrate is imported from the circulation across the plasma membrane into liver cells mainly by the sodium-dependent citrate transporter (NaCT; SLC13A5). Deletion of NaCT from mice led to metabolic changes similar to caloric restriction; therefore, NaCT has been proposed as an attractive therapeutic target for the treatment of obesity and type 2 diabetes. In this study, we expressed mouse and human NaCT into Xenopus oocytes and examined some basic functional properties of those transporters. Interestingly, striking differences were found between mouse and human NaCT with respect to their sensitivities to citric acid cycle intermediates as substrates for these transporters. Mouse NaCT had at least 20- to 800-fold higher affinity for these intermediates than human NaCT. Mouse NaCT is fully active at physiologic plasma levels of citrate, but its human counterpart is not. Replacement of extracellular sodium by other monovalent cations revealed that human NaCT was markedly less dependent on extracellular sodium than mouse NaCT. The low sensitivity of human NaCT for citrate raises questions about the translatability of this target from the mouse to the human situation and raises doubts about the validity of this transporter as a therapeutic target for the treatment of metabolic diseases in humans. PMID:26324167

  15. Sulfometuron incorporation in cationic micelles adsorbed on montmorillonite.

    Mishael, Yael Golda; Undabeytia, Tomas; Rytwo, Giora; Papahadjopoulos-Sternberg, Brigitte; Rubin, Baruch; Nir, Shlomo


    The aim of this study was to understand the interactions between alkylammonium cations present as monomers and micelles and a clay mineral, montmorillonite, to develop slow release formulations of anionic herbicides, such as sulfometuron (SFM) whose leaching in soils is an environmental and economic problem. In the proposed formulation the herbicide is incorporated in positively charged micelles of quaternary amine cations, which in turn adsorb on the negatively charged clay. The adsorption of hexadecyltrimethylammonium (HDTMA) and octadecyltrimethylammonium (ODTMA) on montmorillonite was studied above and below their critical micelle concentrations (CMC). At concentrations above the CMC, the loading exceeded the clay's cation exchange capacity (CEC) and indicated higher affinity of the cation with the longer alkyl chain. An adsorption model could adequately simulate adsorption at concentrations below the CMC, and yield fair predictions for the effect of ionic strength. The model indicated that above the CMC adsorbed micelles contributed significantly to the amount of ODTMA adsorbed. Evidence for adsorption of ODTMA micelles on montmorillonite was provided by X-ray diffraction, freeze-fracture electron microscopy, and dialysis bag measurements. SFM was not adsorbed directly on the clay mineral, and adsorbed at low levels, when the organic cation was adsorbed as monomers. In contrast, a large fraction of SFM adsorbed on the clay mineral when incorporated in micelles that adsorbed on the clay. PMID:11982411

  16. Cationic polymers and their self-assembly for antibacterial applications.

    Deka, Smriti Rekha; Sharma, Ashwani Kumar; Kumar, Pradee


    The present article focuses on the amphiphilic cationic polymers as antibacterial agents. These polymers undergo self-assembly in aqueous conditions and impart biological activity by efficiently interacting with the bacterial cell wall, hence, used in preparing chemical disinfectants and biocides. Both cationic charge as well as hydrophobic segments facilitate interactions with the bacterial cell surface and initiate its disruption. The perturbation in transmembrane potential causes leakage of cytosolic contents followed by cell death. Out of two categories of macromolecules, peptide oligomers and cationic polymers, which have extensively been used as antibacterials, we have elaborated on the current advances made in the area of cationic polymer-based (naturally occurring and commonly employed synthetic polymers and their modified analogs) antibacterial agents. The development of polymer-based antibacterials has helped in addressing challenges posed by the drug-resistant bacterial infections. These polymers provide a new platform to combat such infections in the most efficient manner. This review presents concise discussion on the amphiphilic cationic polymers and their modified analogs having low hemolytic activity and excellent antibacterial activity against array of fungi, bacteria and other microorganisms. PMID:25858132

  17. Novel 1,3-diacylamidopropane-2-[bis-(2-dimethylaminoethane)] carbamate pH-sensitive lipids for cationic liposome-mediated transfection

    Spelios, Michael G.

    A novel series of 1,3-diacylamidopropane-2-[bis(2-dimethylaminoethane)] carbamate analogs (1,3lb) were designed for cationic lipid-assisted transfection (lipofection). First, their physicochemical properties in self-assemblies with and without plasmid DNA (pDNA) were evaluated to examine the effects of hydrophobic tail length and degree of saturation on gene delivery and expression. Significant in vitro lipofection was induced at a nitrogen:phosphate ratio (N:P) of 4:1 by the dimyristoyl, dipalmitoyl, and dioleoyl analogs 1,3lb2, 1,3lb3, and 1,3lb5, respectively, without inclusion of neutral "lipofection enhancing" co-lipids in the cationic lipid formulations. Lipofection was reduced in the presence of co-lipids except for 1,3lb5 which maintained reporter gene expression levels at N:P 4:1 and yielded increased bioactivity at a lower NP of 2:1. Physicochemical characterization of the bioactive transfection agents (cytofectins) revealed: high hydration and in-plane elasticity of lipid monolayers by Langmuir film balance measurements; fluid lipid bilayers, with gel---liquid crystalline phase transitions below physiological temperature, by fluorescence anisotropy; lipid mixing with biomembrane-mimicking vesicles by fluorescence resonance energy transfer; efficient pDNA binding and compaction by ethidium bromide displacement; cationic liposome---nucleic acid complexes (lipoplexes) with large particle sizes (mean diameter ≥ 500 nm) and zeta potentials of positive values by dynamic light scattering and electrophoretic mobility, respectively. The results suggest that well hydrated and elastic cationic lipids forming fluid lamellar assemblies are extremely potent and minimally toxic cytofectins. Second, a comparison was made between 1,3lb2 and two derivatives, one an isomer with a shorter space between the myristoyl chains and the other the monovalent form, in an effort to delineate the biological effects of interchain distance and pH-induced polar headgroup expandability

  18. Cationization of Alpha-Cellulose to Develop New Sustainable Products

    Ana Moral


    Full Text Available Papermaking has been using high quantities of retention agents, mainly cationic substances and organic compounds such as polyamines. The addition of these agents is related to economic and environmental issues, increasing contamination of the effluents. The aim of this work is to develop a cationic polymer for papermaking purposes based on the utilization of alpha-cellulose. The cationization of mercerized alpha-cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC is governed by a pseudo-second-order reaction. The initial amorphous fraction of cellulose is reacted with CHPTAC until the equilibrium value of nitrogen substitution is reached. Nitrogen is incorporated as a quaternary ammonium group in the polymer. Also, the kinetic constant increased with decreasing crystallinity index, showing the importance of the previous alkalization stage. The use of modified natural polysaccharides is a sustainable alternative to synthetic, nonbiodegradable polyelectrolytes and thus is desirable with a view to developing new products and new processes.

  19. Magnetic susceptibilities of actinide cations in aqueous solution

    Paramagnetic cations serve as a useful and efficient NMR probes of coordination environment and can also give insight into dynamics on the millisecond timescale. In an effort to extend the powerful analytical techniques employed with the lanthanide series, some studies to characterize the actinide paramagnetic behavior have been undertaken in our labs under the auspices of the European ACTINET Integrated Infrastructure Initiative and the DOE, NEUP program. We will present a series of magnetic susceptibility measurements spanning all of the readily accessible actinide cations. Variable temperature data has been collected to gather information on the ground electronic state of the cations. The effects of the counter anion in solution are also discussed as they relate to 'softness' and the apparent reduction in free electron character on the metal. Comparisons with first-order Van Vleck and Russell-Saunders predictions will also be shown. (authors)

  20. Changing of Cations Concentrations in Waters of Polluted Urban River

    Andrianova Maria


    Full Text Available Water from urban river Okhta polluted with domestic and industrial wastewaters was investigated. Specific electric conductivity (k, molar concentrations of ions Na+, K+, Mg++ and Ca++, concentration of total nitrogen (TN were measured in water samples. Increasing of k happened together with increasing of molar fraction of sodium-ion (RNa among all studied cations (and correspondingly decreasing of molar fractions of other cations. Good correlations were found between RNa and TN (r = 0.67, k and TN (r = 0.84. The results support the idea of the leading role of wastewaters in changing of k and cations concentrations. Electric conductivity and RNa could be used to distinguish between polluted and not polluted waters in the Okhta.

  1. Surface hopping investigation of the relaxation dynamics in radical cations

    Assmann, Mariana; Matsika, Spiridoula, E-mail: [Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States); Weinacht, Thomas [Department of Physics, Stony Brook University, Stony Brook, New York 11794 (United States)


    Ionization processes can lead to the formation of radical cations with population in several ionic states. In this study, we examine the dynamics of three radical cations starting from an excited ionic state using trajectory surface hopping dynamics in combination with multiconfigurational electronic structure methods. The efficiency of relaxation to the ground state is examined in an effort to understand better whether fragmentation of cations is likely to occur directly on excited states or after relaxation to the ground state. The results on cyclohexadiene, hexatriene, and uracil indicate that relaxation to the ground ionic state is very fast in these systems, while fragmentation before relaxation is rare. Ultrafast relaxation is facilitated by the close proximity of electronic states and the presence of two- and three-state conical intersections. Examining the properties of the systems in the Franck-Condon region can give some insight into the subsequent dynamics.

  2. A covalent attraction between two molecular cation TTF·~+


    The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  3. Radical Addition to Iminium Ions and Cationic Heterocycles

    Johannes Tauber


    Full Text Available Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta reaction, and the Knabe rearrangement will be discussed along with transition metal and photoredox catalysis or electrochemical methods to generate the odd-electron species.

  4. Gamma-irradiated cationic starches: Paper surface-sizing agents

    Cationic starches, precisely depolymerized by gamma-irradiation (60Co), were dispersed in mild alkali and evaluated as surface sizes for bond paper on a pilot paper machine. The irradiated products had excellent dispersion properties, were well retained on fibers when sized wastepaper (broke) was repulped and had an ability to enhance paper properties that was comparable to that of starch-based materials used commercially. A yellow corn flour, cationized by an essentially dry reaction process recently developed at this Center, was also radiolyzed and evaluated as a size. This latter product was unique in that all drying steps were eliminated in the preparation of a cationic ceral product of reduced viscosity. (orig.)

  5. Low-Temperature Cationic Rearrangement in a Bulk Metal Oxide.

    Li, Man-Rong; Retuerto, Maria; Stephens, Peter W; Croft, Mark; Sheptyakov, Denis; Pomjakushin, Vladimir; Deng, Zheng; Akamatsu, Hirofumi; Gopalan, Venkatraman; Sánchez-Benítez, Javier; Saouma, Felix O; Jang, Joon I; Walker, David; Greenblatt, Martha


    Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic-scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also high pressure in bulk oxide materials. Herein, we present the cationic rearrangement in bulk Mn2 FeMoO6 at unparalleled low temperatures of 150-300 (o) C. The irreversible ionic motion at ambient pressure, as evidenced by real-time powder synchrotron X-ray and neutron diffraction, and second harmonic generation, leads to a transition from a Ni3 TeO6 -type to an ordered-ilmenite structure, and dramatic changes of the electrical and magnetic properties. This work demonstrates a remarkable cationic rearrangement, with corresponding large changes in the physical properties in a bulk oxide at unprecedented low temperatures. PMID:27203790

  6. Effect of cation exchange of major cation chemistry in the large scale redox experiment at Aespoe. Revision 1

    Geochemical modeling was used to test the hypothesis that cation exchange with fracture-lining clays during fluid mixing in the Aespoe Hard Rock Laboratory can significantly affect major element chemistry. Conservative mixing models do not adequately account for changes in Na, Ca and Mg concentrations during mixing. Mixing between relatively dilute shallow waters and more concentrated waters at depth along fracture zones was modeled using the EQ3/6 geochemical modeling package. A cation exchange model was added to the code to describe simultaneously aqueous speciation, mineral precipitation/dissolution, and equilibration between a fluid and a cation exchanger. Fluid chemistries predicted to result from mixing were compared with those monitored from boreholes intersecting the fracture zone. Modeling results suggest that less than 0.1 equivalent of a smectite exchanger per liter of groundwater is necessary to account for discrepancies between predictions from a conservative mixing model and measured Na and Ca concentrations. This quantity of exchanger equates to an effective fracture coating thickness of 20 microm or less given a fracture aperture width of 1,000 microm or less. Trends in cation ratios in the fluid cannot be used to predict trends in cation ratios on the exchanger because of the influence of ionic strength on heterovalent exchange equilibrium. It is expected that Na for Ca exchange will dominate when shallow waters such as HBHO2 are mixed with deeper waters. In contrast, Na for Mg exchange will dominate mixing between deeper waters

  7. Modeling cation exchange using EQ3/6

    Geochemical modeling codes must be able to predict solid-solution and ion-exchange behavior of zeolites and smectites in order to design and assess strategies for containing and cleaning up toxic and/or radioactive wastes. Cation-exchange and solid-solution models have been implemented in the EQ3/6 geochemical modeling package and used to predict the composition of clinoptilolite under a variety of conditions. Published free energies of cation exchange on clinoptilolite at 25 degrees C were combined with the calorimetric data for clinoptilolite to derive free energies of formation of the component end members of a solid solution in which mixing is allowed only on the exchange site. The solid-solution model and component end-member data were incorporated into EQ3/6 and its data base. An option to treat cation exchange independently of the solid-solution model was also developed and implemented in EQ3/6. This option allows the user to model mixed-phase exchangers, multisite exchangers, and systems in which the exchanger is not in overall equilibrium with the solution. Two open-quotes idealclose quotes cation-exchange conventions [Vanselow (mole fraction) and Gapon (equivalent fraction)] are currently implemented in the code. A description of the cation-exchange models and their implementation into EQ3/6 is presented, and the relationship between the exchange formalisms and the solid-solution models is discussed. The advantages and limitations of the models and currently available thermodynamic data are addressed by comparing cation-exchange compositions of clinoptilolites with (1) published binary exchange data; (2) compositions of coexisting clinoptilolites and formation waters at Yucca Mountain; and (3) experimental sorption isotherms of Cs and Sr on zeolitized tuff

  8. Radiation-induced cationic curing of vinyl ethers

    Recently there has been an increasing interest in nonacrylate radiation-curable coatings. Vinyl ethers are particularly reactive under cationic polymerization reaction conditions. The high efficiency of the photoacid initiators combined with the high reactivity of vinyl ether monomers makes this a potentially very useful system. This chapter discusses the preparation of vinyl ethers, introduces vinyl ether-functional monomers and oligomers, describes radiation-induced cationic polymerization of vinyl ethers, and discusses various coating systems. Throughout the chapter, an emphasis is placed on radiation-curable coating applications. 64 refs., 5 figs., 11 tabs

  9. Formation and Dissociation of Phosphorylated Peptide Radical Cations

    Kong, Ricky P. W.; Quan, Quan; Hao, Qiang; Lai, Cheuk-kuen; Siu, Chi-Kit; Chu, Ivan K.


    In this study, we generated phosphoserine- and phosphothreonine-containing peptide radical cations through low-energy collision-induced dissociation (CID) of the ternary metal–ligand phosphorylated peptide complexes [CuII(terpy) p M]·2+ and [CoIII(salen) p M]·+ [ p M: phosphorylated angiotensin III derivative; terpy: 2,2':6',2''-terpyridine; salen: N,N '-ethylenebis(salicylideneiminato)]. Subsequent CID of the phosphorylated peptide radical cations ( p M·+) revealed fascinating gas-phase radi...

  10. Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

    Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen


    We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...... disconnected glass phase....