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Sample records for weak base anion

  1. Evaluating of arsenic(V) removal from water by weak-base anion exchange adsorbents.

    Science.gov (United States)

    Awual, M Rabiul; Hossain, M Amran; Shenashen, M A; Yaita, Tsuyoshi; Suzuki, Shinichi; Jyo, Akinori

    2013-01-01

    Arsenic contamination of groundwater has been called the largest mass poisoning calamity in human history and creates severe health problems. The effective adsorbents are imperative in response to the widespread removal of toxic arsenic exposure through drinking water. Evaluation of arsenic(V) removal from water by weak-base anion exchange adsorbents was studied in this paper, aiming at the determination of the effects of pH, competing anions, and feed flow rates to improvement on remediation. Two types of weak-base adsorbents were used to evaluate arsenic(V) removal efficiency both in batch and column approaches. Anion selectivity was determined by both adsorbents in batch method as equilibrium As(V) adsorption capacities. Column studies were performed in fixed-bed experiments using both adsorbent packed columns, and kinetic performance was dependent on the feed flow rate and competing anions. The weak-base adsorbents clarified that these are selective to arsenic(V) over competition of chloride, nitrate, and sulfate anions. The solution pH played an important role in arsenic(V) removal, and a higher pH can cause lower adsorption capacities. A low concentration level of arsenic(V) was also removed by these adsorbents even at a high flow rate of 250-350 h(-1). Adsorbed arsenic(V) was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for the next adsorption operation after rinsing with water. The weak-base anion exchange adsorbents are to be an effective means to remove arsenic(V) from drinking water. The fast adsorption rate and the excellent adsorption capacity in the neutral pH range will render this removal technique attractive in practical use in chemical industry.

  2. Guidelines for selecting weak-base versus strong-base anion-exchange resins for the recovery of chromate from cooling tower blowdown

    Energy Technology Data Exchange (ETDEWEB)

    Newman, J.; Reed, L.W.

    1980-01-01

    Guidelines for selecting weak-base versus strong-base anion-exchange resins for the recovery of chromate from cooling tower blowdown are given, together with actual operating data on large-scale industrial systems based on strong-base anion-exchange resins, data from a similar pilot system based on weak-base anion resin, and the chemical costs for operating both systems for a cooling tower blowdown containing 2500 ppm total dissolved solids and 20 ppm chromata.

  3. A weak-base fibrous anion exchanger effective for rapid phosphate removal from water.

    Science.gov (United States)

    Awual, Md Rabiul; Jyo, Akinori; El-Safty, Sherif A; Tamada, Masao; Seko, Noriaki

    2011-04-15

    This work investigated that weak-base anion exchange fibers named FVA-c and FVA-f were selectively and rapidly taken up phosphate from water. The chemical structure of both FVA-c and FVA-f was the same; i.e., poly(vinylamine) chains grafted onto polyethylene coated polypropylene fibers. Batch study using FVA-c clarified that this preferred phosphate to chloride, nitrate and sulfate in neutral pH region and an equilibrium capacity of FVA-c for phosphate was from 2.45 to 6.87 mmol/g. Column study using FVA-f made it clear that breakthrough capacities of FVA-f were not strongly affected by flow rates from 150 to 2000 h(-1) as well as phosphate feed concentration from 0.072 to 1.6mM. Under these conditions, breakthrough capacities were from 0.84 to 1.43 mmol/g indicating high kinetic performances. Trace concentration of phosphate was also removed from feeds containing 0.021 and 0.035 mM of phosphate at high feed flow rate of 2500 h(-1), breakthrough capacities were 0.676 and 0.741 mmol/g, respectively. The column study also clarified that chloride and sulfate did not strongly interfere with phosphate uptake even in their presence of equimolar and fivefold molar levels. Adsorbed phosphate on FVA-f was quantitatively eluted with 1M HCl acid and regenerated into hydrochloride form simultaneously for next phosphate adsorption operation. Therefore, FVA-f is able to use long time even under rigorous chemical treatment of multiple regeneration/reuse cycles without any noticeable deterioration. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Large-Scale Demonstration of Perchlorate Removal Using Weak Base Anion Resin at Well No. 3 in Rialto, California

    Science.gov (United States)

    2012-12-01

    alkalinity/ stripping of CO2 from the groundwater feed can be accomplished using membrane treatment systems or stripping towers. Both methods are...pH- dependent nature of WBA resins. At low pH, WBA functional groups on the resin have a positive charge (i.e., R- NH3 +), allowing anion exchange to...R-NH2) is ionized (R- NH3 +) by protonating with acid (H+): R-NH2 + H+  R- NH3 + Protonated resin removes anions (A-) from aqueous streams: R- NH3 + + A

  5. Dissolution of metal salts in bis(trifluoromethylsulfonyl)imide-based ionic liquids: studying the affinity of metal cations toward a "weakly coordinating" anion.

    Science.gov (United States)

    Bortolini, Olga; Chiappe, Cinzia; Ghilardi, Tiziana; Massi, Alessandro; Pomelli, Christian Silvio

    2015-05-28

    Despite the weakly coordinating ability of the bis(trifluoromethylsulfonyl)imide anion ([Tf2N](-)) the corresponding ionic liquids (ILs) are able to dissolve relevant amounts of metal salts having the same anion, M[Tf2N]x. To better understand the metal dissolution process we evaluated the interaction ability of a set of metal cations (Y(III), Al(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Li(I), and Na(I)) toward the [Tf2N](-) anion measuring the relative aptitude to give the corresponding anionic monocharged complex, [M(Tf2N)x+1](-) using the ESI-MS technique. UV-vis and NMR measurements were carried out to verify the consistence between the liquid and the gas phase. Density functional theory calculations have been used to identify the metal-containing species and determine their relative stability. An interesting correlation between interaction ability and chemical properties (Lewis acidity) was found.

  6. Use of weak ion association in the separation of inorganic anions by ...

    African Journals Online (AJOL)

    In this work weak ion association was used to effect selectivity and detection of inorganic anions with environmental or health significance by capillary electropheresis, CE. Tetrabutylammonium ion was used as a pairing anion to separate mixtures containing closely or co-migrating inorganic anions at pHs 3.8 and pH 7.

  7. Hofmeister Effect on PNIPAM in Bulk and at an Interface: Surface Partitioning of Weakly Hydrated Anions

    DEFF Research Database (Denmark)

    Moghaddam, Saeed Zajforoushan; Thormann, Esben

    2017-01-01

    microbalance, and atomic force microscopy. The results indicate a surface partitioning of the weakly hydrated anions, i.e., thiocyanate and trichloroacetate, and the findings are discussed in terms of anion-induced electrostatic stabilization. Although attractive polymer-ion interactions are suggested...... for thiocyanate and trichloroacetate, a salting-out effect is found for sodium trichloroacetate. This apparent contradiction is explained by a combination of previously suggested mechanisms for the salting-out effect by weakly hydrated anions....

  8. Evaluation of glycidyl methacrylate-based monolith functionalized with weak anion exchange moiety inside 0.5 mm i.d. column for liquid chromatographic separation of DNA

    Directory of Open Access Journals (Sweden)

    Aprilia Nur Tasfiyati

    2016-03-01

    Full Text Available In this study, the organic polymer monolith was developed as a weak anion exchanger column in high performance liquid chromatography for DNA separation. Methacrylate-based monolithic column was prepared in microbore silicosteel column (100 × 0.5 mm i.d. by in-situ polymerization reaction using glycidyl methacrylate as monomer; ethylene dimethacrylate as crosslinker; 1-propanol, 1,4-butanediol, and water as porogenic solvents, with the presence of initiator α,α′-azobisisobutyronitrile (AIBN. The monolith matrix was modified with diethylamine to create weak anion exchanger via ring opening reaction of epoxy groups. The morphology of the monolithic column was studied by SEM. The properties of the monolithic column, such as permeability, mechanical stability, binding capacity and pore size distribution, were characterized in detail. From the results of the characterization, monoliths poly-(GMA-co-EDMA with total monomer percentage (%T 40 and crosslinker percentage (%C 25 was found to be the ideal composition of monomer and crosslinker. It has good mechanical stability and high permeability, adequate molecular recognition sites (represented with binding capacity value of 36 mg ml−1, and has relatively equal proportion of flow-through pore and mesopores (37.2% and 41.1% respectively. Poly-(GMA-co-EDMA with %T 40 and %C 25 can successfully separate oligo(dT12–18 and 50 bp DNA ladder with good resolution.

  9. Reactive p-block cations stabilized by weakly coordinating anions

    Science.gov (United States)

    Engesser, Tobias A.; Lichtenthaler, Martin R.; Schleep, Mario

    2016-01-01

    The chemistry of the p-block elements is a huge playground for fundamental and applied work. With their bonding from electron deficient to hypercoordinate and formally hypervalent, the p-block elements represent an area to find terra incognita. Often, the formation of cations that contain p-block elements as central ingredient is desired, for example to make a compound more Lewis acidic for an application or simply to prove an idea. This review has collected the reactive p-block cations (rPBC) with a comprehensive focus on those that have been published since the year 2000, but including the milestones and key citations of earlier work. We include an overview on the weakly coordinating anions (WCAs) used to stabilize the rPBC and give an overview to WCA selection, ionization strategies for rPBC-formation and finally list the rPBC ordered in their respective group from 13 to 18. However, typical, often more organic ion classes that constitute for example ionic liquids (imidazolium, ammonium, etc.) were omitted, as were those that do not fulfill the – naturally subjective – “reactive”-criterion of the rPBC. As a rule, we only included rPBC with crystal structure and only rarely refer to important cations published without crystal structure. This collection is intended for those who are simply interested what has been done or what is possible, as well as those who seek advice on preparative issues, up to people having a certain application in mind, where the knowledge on the existence of a rPBC that might play a role as an intermediate or active center may be useful. PMID:26612538

  10. Theoretical Probing of Weak Anion-Cation Interactions in Certain Pyridinium based Ionic Liquid Ion-Pairs and the Application of Molecular Electrostatic Potential in their Ionic Crystal Density Determination : A Comparative Study Using Density Functional Approach.

    Science.gov (United States)

    Joseph, Aswathy; Thomas, Vibin Ipe; Żyła, Gaweł; Alapat, Padmanabhan Sridharan; Mathew, Suresh

    2017-11-07

    A comprehensive study on the structure, nature of interaction and properties of six ionic pairs of 1-butylpyridinium and 1-butyl-4-methylpyridinium cations in combination with tetrafluoroborate (BF4-), chloride (Cl-) and bromide (Br-) anions have been carried out using Density Functional Theory (DFT). The anion-cation interaction energy (ΔEint), theoretical band gap, molecular orbital energy-order, DFT-based chemical activity descriptors: chemical potential (μ), chemical hardness (η) and electrophilicity index (ω) and distribution of density of states (DOS) of these ion-pairs were investigated. The ascendancy of -CH3 substituent at the 4th position of the 1-butylpyridinium cation ring on the values of ΔEint, theoretical band gap and chemical activity descriptors was evaluated. The ΔEint values were negative for all the six ion-pairs and were highest for Cl- containing ion-pairs. The theoretical band-gap value after -CH3 substitution increased from 3.78 to 3.96 eV (for Cl-) and from 2.74 to 2.88 eV (for Br-) and decreased from 4.9 to 4.89 eV (for BF4-). Ion-pairs of BF4- were more susceptible to charge transfer processes as inferred from their significantly high η values and comparatively small difference in ω value after -CH3 substitution. The change in η and μ values due to the -CH3 substituent is negligibly small in all cases except for the ion-pairs of Cl-. The entropy change (ΔS) was negative for all the ion-pairs. Critical point (CP) analysis were carried out to investigate the AIM topological parameters at the inter-ionic bond critical points (BCPs). The RDG isosurface analysis indicated that anion-cation interaction was dominated by strong Hcat….Xani and Ccat….Xani interactions in ion-pairs of Cl- and Br- whereas weak van der Waal's effect dominated in ion-pairs of BF4-. The molecular electrostatic potential (MESP) based parameter ΔΔVmin measuring the anion-cation interaction strength showed a good linear correlation with ΔEint for all 1

  11. Selective anion exchange and tunable luminescent behaviors of metal-organic framework based supramolecular isomers.

    Science.gov (United States)

    Manna, Biplab; Singh, Shweta; Karmakar, Avishek; Desai, Aamod V; Ghosh, Sujit K

    2015-01-05

    Owing to the conformational (cis or trans) flexibility of a N-donor ligand, the combinations of the same and Cd(ClO4)2 under variable solvent templates afforded two supramolecular isomers based on two-dimensional metal-organic frameworks. Both compounds contain weakly coordinating ClO4(-) anions attached to the metal centers. Both frameworks showed facile anion exchange behaviors with various kinds of foreign anions. Moreover, both frameworks showed anion-driven structural dynamism and exhibited the preferential uptake of strongly coordinating anions over others. Anion-regulated modulation in luminescent behaviors was also observed in both cases.

  12. Preparation of a weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography stationary phase for protein separation using click chemistry.

    Science.gov (United States)

    Zhao, Kailou; Yang, Fan; Xia, Hongjun; Wang, Fei; Song, Qingguo; Bai, Quan

    2015-03-01

    In this study, 3-diethylamino-1-propyne was covalently bonded to the azide-silica by a click reaction to obtain a novel dual-function mixed-mode chromatography stationary phase for protein separation with a ligand containing tertiary amine and two ethyl groups capable of electrostatic and hydrophobic interaction functionalities, which can display hydrophobic interaction chromatography character in a high-salt-concentration mobile phase and weak anion exchange character in a low-salt-concentration mobile phase employed for protein separation. As a result, it can be employed to separate proteins with weak anion exchange and hydrophobic interaction modes, respectively. The resolution and selectivity of the stationary phase were evaluated in both hydrophobic interaction and ion exchange modes with standard proteins, respectively, which can be comparable to that of conventional weak anion exchange and hydrophobic interaction chromatography columns. Therefore, the synthesized weak anion exchange/hydrophobic interaction dual-function mixed-mode chromatography column can be used to replace two corresponding conventional weak anion exchange and hydrophobic interaction chromatography columns to separate proteins. Based on this mixed-mode chromatography stationary phase, a new off-line two-dimensional liquid chromatography technology using only a single dual-function mixed-mode chromatography column was developed. Nine kinds of tested proteins can be separated completely using the developed method within 2.0 h. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Designation and Exploration of Halide-Anion Recognition Based on Cooperative Noncovalent Interactions Including Hydrogen Bonds and Anion-π.

    Science.gov (United States)

    Liu, Yan-Zhi; Yuan, Kun; Lv, Ling-Ling; Zhu, Yuan-Cheng; Yuan, Zhao

    2015-06-04

    A novel urea-based anion receptor with an electron-deficient aromatic structural unit, N-p-nitrophenyl-N-(4-vinyl-2-five-fluoro-benzoic acid benzyl ester)-phenyl-urea (FUR), was designed to probe the potential for halide-anion recognition through the cooperation of two distinct noncovalent interactions including hydrogen bonds and anion-π in this work. The nature of the recognition interactions between halide-anion and the designed receptor was theoretically investigated at the molecular level. The geometric features of the hydrogen bond and anion-π of the FUR@X(-) (X = F, Cl, Br, and I) systems were thoroughly investigated. The binding energies and thermodynamic information on the halide-anion recognitions show that the presently designed FUR might selectively recognize anion F(-) based on the cooperation of the N-H···F(-) hydrogen bond and anion-π interactions both in vacuum and in solvents. IR and UV-visible spectra of free FUR and FUR@F(-) have been simulated and discussed qualitatively, which may be helpful for further experimental investigations in the future. Additionally, the electronic properties and behaviors of the FUR@X(-) systems were discussed according to the calculations on the natural bond orbital (NBO) data, molecular electrostatic potential (MEP), and weak interaction regions.

  14. Adsorption behavior of benzenesulfonic acid by novel weakly basic anion exchange resins.

    Science.gov (United States)

    Sun, Yue; Zuo, Peng; Luo, Junfen; Singh, Rajendra Prasad

    2017-04-01

    Two novel weakly basic anion exchange resins (SZ-1 and SZ-2) were prepared via the reaction of macroporous chloromethylated polystyrene-divinylbenzene (Cl-PS-DVB) beads with dicyclohexylamine and piperidine, respectively. The physicochemical structures of the resulting resins were characterized using Fourier Transform Infrared Spectroscopy and pore size distribution analysis. The adsorption behavior of SZ-1 and SZ-2 for benzenesulfonic acid (BA) was evaluated, and the common commercial weakly basic anion exchanger D301 was also employed for comparison purpose. Adsorption isotherms and influence of solution pH, temperature and coexisting competitive inorganic salts (Na 2 SO 4 and NaCl) on adsorption behavior were investigated and the optimum desorption agent was obtained. Adsorption isotherms of BA were found to be well represented by the Langmuir model. Thermodynamic parameters involving ΔH, ΔG and ΔS were also calculated and the results indicate that adsorption is an exothermic and spontaneous process. Enhanced selectivity of BA sorption over sulfate on the two novel resins was observed by comparison with the commercial anion exchanger D301. The fact that the tested resins loaded with BA can be efficiently regenerated by NaCl solution indicates the reversible sorption process. From a mechanistic viewpoint, this observation clearly suggests that electrostatic interaction is the predominant adsorption mechanism. Furthermore, results of column tests show that SZ-1 possesses a better adsorption property than D301, which reinforces the feasibility of SZ-1 for potential industrial application. Copyright © 2016. Published by Elsevier B.V.

  15. Gallium based low-interaction anions

    Science.gov (United States)

    King, Wayne A.; Kubas, Gregory J.

    2000-01-01

    The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

  16. Gels based on anion recognition between triurea receptor and phosphate anion.

    Science.gov (United States)

    Yang, Cuiling; Wu, Biao; Chen, Yongming; Zhang, Ke

    2015-04-01

    Anion recognition between the triurea receptor and phosphate anion is demonstrated as the cross-linkage to build supramolecular polymer gels for the first time. A novel multi-block copolymer (3) is designed to have functional triurea groups as cross-linking units along the polymer main chain. By virtue of anion coordination between the triurea receptor and phosphate anion with a binding mode of 2:1, supramolecular polymer gels are then prepared based on anion recognition using 3 as the building block. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Determination of trace inorganic anions in weak acids by single-pump column-switching ion chromatography.

    Science.gov (United States)

    Zhu, Haibao; Chen, Huadong; Zhong, Yingying; Ren, Dandan; Qian, Yaling; Tang, Hongfang; Zhu, Yan

    2010-08-01

    Ion chromatography has been proposed for the determination of three common inorganic anions (chloride, nitrate, and sulfate) in nine weak acids (tartaric acid, citric acid, formic acid, acetic acid, metacetonic acid, butyric acid, butanedioic acid, hexafluorophosphoric acid, and salicylic acid) using a single pump, two valves, a single eluent, and a single conductivity detector. The present system uses ion exclusion, concentrator, and anion-exchange columns connected in series via 6-port and 10-port valves in a Dionex ICS-2100 ion chromatograph. The valves were switched for the determination of three inorganic anions from weak acids in a single chromatographic run. Sample matrices of weak acids with a series of concentrations can be investigated. Complete separations of the previously mentioned anions are demonstrated within 40 min. Under the optimum conditions, the relative standard deviation values ranged from 1.3 to 3.8%. The detection limits of the three inorganic anions (S/N = 3) were in the range of 0.3-1.7 microg/L. The recoveries were in the range of 75.2-117.6%. With this system, automation for routine analysis, short analysis time, and low cost can be achieved.

  18. The development of a weak anion micro-capillary film for protein chromatography.

    Science.gov (United States)

    Kouyoumdjian, A J M; Lazar, R A; Slater, N K H

    2016-10-14

    In this study, the surface of a microporous walled micro-capillary film (MMCF) was modified into a weak anion exchanger by coupling cyanuric chloride and 2-diethylaminoethylamine (DEAE) to the ethylene-vinyl alcohol (EVOH) matrix. Fourier transform infrared spectroscopy (FTIR) measurements of modified and unmodified MMCFs confirmed the addition of a triazine ring and DEAE onto the membrane. Binding of bovine serum albumin (BSA) at pH 7.2 was found to follow a Langmuir isotherm with a maximum equilibrium binding of 12.4mg BSA/mL adsorbent and 8.2mg BSA/mL adsorbent under static and flow conditions, respectively. The ion exchange capacity, determined by Mohr's titration of chlorine atoms displaced from the functionalised surface, was found to be 195±21μmol Cl - /mL of adsorber, comparable to commercial ion exchangers. BSA adsorption onto the ion exchanger was strongly pH-dependant, with an observed reduction in binding above pH 8.2. Frontal experiments of a BSA (5mg/mL) and lysozyme (5mg/mL) mixture demonstrated successful separation of BSA from lysozyme at more than 97% purity as verified by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Separation between similarly charged anionic molecules was also achieved using BSA (5mg/mL) and herring sperm DNA (0.25mg/mL). BSA was extracted at 100% purity, demonstrating the ability of MMCF-DEAE to remove significant DNA contamination from a protein solution. These experiments highlight the potential for MMCFs to be used for fast protein purification in preparative chromatography application. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Features of the adsorption of naproxen enantiomers on weak chiral anion-exchangers in nonlinear chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Asnin, Leonid [University of Tennessee, Knoxville (UTK); Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

    2008-01-01

    The retention mechanism of the enantiomers of naproxen on a Pirkle-type chiral stationary phase (CSP) was studied. This CSP is made of a porous silica grafted with quinidine carbamate. It can interact with the weak organic electrolyte naproxen either by adsorbing it or by ion-exchange. Using frontal chromatography, we explored the adsorption equilibrium under such experimental conditions that naproxen dissociates or cannot dissociate. Under conditions preventing ionic dissociation, the adsorption isotherms were measured, the adsorption energy distributions determined, and the chromatographic profiles calculated. Three different types of the adsorption sites were found for both enantiomers. The density and the binding energy of these sites depend on the nature of the organic modifier. Different solute species, anions, neutral molecules, solvent-ion associates, and solute dimers can coexist in solution, giving rise to different forms of adsorption. This study showed the unexpected occurrence of secondary steps in the breakthrough profiles of S-naproxen in the adsorption mode at high concentrations. Being enantioselective, this phenomenon was assumed to result from the association of solute molecules involving a chiral selector moiety. A multisite Langmuir adsorption model was used to calculate band profiles. Although this model accounts excellently for the experimental adsorption isotherms, it does not explain all the features of the breakthrough profiles. A comparison between the calculated and experimental profiles allowed useful conclusions concerning the effects of the adsorbate-adsorbate and adsorbate-solvent interactions on the adsorption mechanism.

  20. High-speed simultaneous ion-exclusion/cation-exchange chromatography of anions and cations on a weakly acidic cation-exchange resin column.

    Science.gov (United States)

    Mori, Masanobu; Tanaka, Kazuhiko; Helaleh, Murad I H; Xu, Qun; Ikedo, Mikaru; Ogura, Yutaka; Sato, Shinji; Hu, Wenzhi; Hasebe, Kiyoshi; Haddad, Paul R

    2003-05-16

    The simultaneous ion-exclusion/cation-exchange separation column packed with a polymethacrylate-based weakly acidic cation-exchange resin of 3 microm particle size was used to achieve the simultaneous high-speed separation of anions and cations (Cl(-), NO3(-), SO4(2-), Na(+), K(+), NH4(+), Ca(2+) and Mg(2+)) commonly found in environmental samples. The high-speed simultaneous separation is based on a combination of the ion-exclusion mechanism for the anions and the cation-exchange mechanism for cations. The complete separation of the anions and cations was achieved in 5 min by elution with 15 mM tartaric acid-2.5 mM 18-crown-6 at a flow-rate of 1.5 ml/min. Detection limits at S/N=3 ranged from 0.36 to 0.68 microM for anions and 0.63-0.99 microM for cations. This method has been applied to the simultaneous determination of anions and cations in several environmental waters with satisfactory results.

  1. Concurrent high-sensitivity conductometric detection of volatile weak acids in a suppressed anion chromatography system.

    Science.gov (United States)

    Liao, Hongzhu; Kadjo, Akinde Florence; Dasgupta, Purnendu K

    2015-08-18

    A suppressed hydroxide eluent anion chromatograph effluent flows through the outside of a gas-permeable membrane tube while electrogenerated 100-200 μM LiOH flows through the lumen into a second conductivity detector. Undissociated volatile acid eluites (e.g., H2S, HCN, H2CO3, etc., represented as HA) transfer through the membrane and react as OH(-) + HA → A(-) + H2O; the conversion of high-mobility OH(-) to lower mobility A(-) results in a significant negative response for these analytes. With the chromatograph operated at a macroscale (0.3 mL/min) the LiOH flow can be 3-30-fold lower, resulting in corresponding enrichment of the transferred analyte prior to detection. Because there is no mixing of liquids, the detector noise is very low (detector. Thus, despite a background of 25-45 μS/cm, limits of detection for sulfide and cyanide are in the submicromolar level, with a linear dynamic range up to 100 μM. Carbonate/bicarbonate can also be sensitively detected. We demonstrate adaptation in a standard commercial system. We also show that Microsoft Excel-based numerical simulations of transport quantitatively predict the observed behavior well.

  2. SIMULATION OF SUBGRADE EMBANKMENT ON WEAK BASE

    Directory of Open Access Journals (Sweden)

    V. D. Petrenko

    2015-08-01

    Full Text Available Purpose. This article provides: the question of the sustainability of the subgrade on a weak base is considered in the paper. It is proposed to use the method of jet grouting. Investigation of the possibility of a weak base has an effect on the overall deformation of the subgrade; the identification and optimization of the parameters of subgrade based on studies using numerical simulation. Methodology. The theoretical studies of the stress-strain state of the base and subgrade embankment by modeling in the software package LIRA have been conducted to achieve this goal. Findings. After making the necessary calculations perform building fields of a subsidence, borders cramped thickness, bed’s coefficients of Pasternak and Winkler. The diagrams construction of vertical stress performs at any point of load application. Also, using the software system may perform peer review subsidence, rolls railroad tracks in natural and consolidated basis. Originality. For weak soils is the most appropriate nonlinear model of the base with the existing areas of both elastic and limit equilibrium, mixed problem of the theory of elasticity and plasticity. Practical value. By increasing the load on the weak base as a result of the second track construction, adds embankment or increasing axial load when changing the rolling stock process of sedimentation and consolidation may continue again. Therefore, one of the feasible and promising options for the design and reconstruction of embankments on weak bases is to strengthen the bases with the help of jet grouting. With the expansion of the railway infrastructure, increasing speed and weight of the rolling stock is necessary to ensure the stability of the subgrade on weak bases. LIRA software package allows you to perform all the necessary calculations for the selection of a proper way of strengthening weak bases.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-05-04

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

  4. Multidimensional separation of tryptic peptides from human serum proteins using reversed-phase, strong cation exchange, weak anion exchange, and fused-core fluorinated stationary phases

    NARCIS (Netherlands)

    Boichenko, Alexander P.; Govorukhina, Natalia; van der Zee, Ate G. J.; Bischoff, Rainer

    2013-01-01

    Proteome profiling of crude serum is a challenging task due to the wide dynamic range of protein concentrations and the presence of high-abundance proteins, which cover >90% of the total protein mass in serum. Peptide fractionation on strong cation exchange, weak anion exchange in the electrostatic

  5. Hydrogen Production from a Methanol-Water Solution Catalyzed by an Anionic Iridium Complex Bearing a Functional Bipyridonate Ligand under Weakly Basic Conditions.

    Science.gov (United States)

    Fujita, Ken-ichi; Kawahara, Ryoko; Aikawa, Takuya; Yamaguchi, Ryohei

    2015-07-27

    An efficient catalytic system for the production of hydrogen from a methanol-water solution has been developed using a new anionic iridium complex bearing a functional bipyridonate ligand as a catalyst. This system can be operated under mild conditions [weakly basic solution (0.046 mol L(-1) NaOH) below 100 °C] without the use of an additional organic solvent. Long-term continuous hydrogen production from a methanol-water solution catalyzed by the anionic iridium complex was also achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Polypropylene based anion exchange fiber for enrichment and ...

    African Journals Online (AJOL)

    Indium was enriched and separated by a new polypropylene based anion exchange fiber before determined by graphite furnace atomic absorption spectrometry (GFAAS). Indium can be enriched quantitatively by 0.1 g of fiber at the flow rate within 6 mL·min-1 in the pH 4 and can be desorbed quantitatively with 10 mL of 1.0 ...

  7. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    Science.gov (United States)

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  8. Part I. Student success in intensive versus traditional introductory chemistry courses. Part II. Synthesis of salts of the weakly coordinating trisphat anion

    Science.gov (United States)

    Hall, Mildred V.

    Part I. Intensive courses have been shown to be associated with equal or greater student success than traditional-length courses in a wide variety of disciplines and education levels. Student records from intensive and traditional-length introductory general chemistry courses were analyzed to determine the effects, of the course format, the level of academic experience, life experience (age), GPA, academic major and gender on student success in the course. Pretest scores, GPA and ACT composite scores were used as measures of academic ability and prior knowledge; t-tests comparing the means of these variables were used to establish that the populations were comparable prior to the course. Final exam scores, total course points and pretest-posttest differences were used as measures of student success; t-tests were used to determine if differences existed between the populations. ANCOVA analyses revealed that student GPA, pretest scores and course format were the only variables tested that were significant in accounting for the variance of the academic success measures. In general, the results indicate that students achieved greater academic success in the intensive-format course, regardless of the level of academic experience, life experience, academic major or gender. Part II. Weakly coordinating anions have many important applications, one of which is to function as co-catalysts in the polymerization of olefins by zirconocene. The structure of tris(tetrachlorobenzenedialato) phosphate(V) or "trisphat" anion suggests that it might be an outstanding example of a weakly coordinating anion. Trisphat acid was synthesized and immediately used to prepare the stable tributylammonium trisphat, which was further reacted to produce trisphat salts of Group I metal cations in high yields. Results of the 35Cl NQR analysis of these trisphat salts indicate only very weak coordination between the metal cations and the chlorine atoms of the trisphat anion.

  9. Influence of acidic eluent for retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography on a weakly acidic cation-exchange resin in the H+ -form.

    Science.gov (United States)

    Mori, Masanobu; Tanaka, Kazuhiko; Satori, Tatsuya; Ikedo, Mikaru; Hu, Wenzhi; Itabashi, Hideyuki

    2006-06-16

    Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) (first dissociation constant) of acid in eluent. The retention behaviors of anions and cations were related to that of elution dip induced after eluting acid to separation column and injecting analyte sample. These results were largely dependent on the natures of acid as eluent. Through this study, succinic acid as the eluent was suitable for simultaneous separation of strong acid anions (SO(4)(2-), Cl(-), NO(3)(-) and I(-)), weak acid anions (F(-), HCOO(-) and CH(3)COO(-)), and cations (Na(+), K(+), NH(4)(+), Mg(2+) and Ca(2+)). The separation was achieved in 20 min under the optimum eluent condition, 20 mM succinic acid/2 mM 18-crown-6. Detection limits at S/N=3 ranged from 0.10 to 0.51 microM for strong acid anions, 0.20 to 5.04 microM for weak acid anions and 0.75 to 1.72 microM for cations. The relative standard deviations of peak areas in the repeated chromatographic runs (n=10) were in the range of 1.1-2.9% for anions and 1.8-4.5% for cations. This method was successfully applied to hot spring water containing strong acid anions, weak acid anions and cations, with satisfactory results.

  10. A tandem laboratory scale protein purification process using Protein A affinity and anion exchange chromatography operated in a weak partitioning mode.

    Science.gov (United States)

    Shamashkin, Michael; Godavarti, Ranga; Iskra, Timothy; Coffman, Jon

    2013-10-01

    A significant consequence of scaling up production of high titer monoclonal antibody (mAb) processes in existing facilities is the generation of in-process pools that exceed the capacity of storage vessels. A semi-continuous downstream process where columns and filters are linked and operated in tandem would eliminate the need for intermediate holding tanks. This study is a bench-scale demonstration of the feasibility of a tandem process for the purification of mAbs employing an affinity Protein A capture step, followed by a flow-through anion-exchange (AEX) step with the possibility of adding an in-line virus filtration step (VF). All three steps were linked sequentially and operated as one continuous process using an ÄKTA FPLC equipped with two pumps and a system of valves and bypasses that allowed the components to be engaged at different stages of the process. The AEX column was operated in a weak partitioning (WP) mode enabled by a precise in-line titration of Protein A effluent. In order to avoid complex control schemes and facilitate validation, quality and robustness were built into the system through selection of buffers based on thermodynamic and empirical models. The tandem system utilized the simplest possible combination of valves, pumps, controls, and automation, so that it could easily be implemented in a clinical or commercial production facility. Linking the purification steps in a tandem process is expected to generate savings in time and production costs and also reduce the size of quality systems due to reduced documentation requirements, microbial sampling, and elimination of hold time validation. Copyright © 2013 Wiley Periodicals, Inc.

  11. Use of anions of C{sub 60} as electrogenerated bases

    Energy Technology Data Exchange (ETDEWEB)

    Niyazymbetov, M.E.; Evans, D.H. [Univ. of Delaware, Newark, DE (United States). Dept. of Chemistry and Biochemistry

    1995-08-01

    C{sub 60} was reduced in the mixed solvent acetonitrile-toluene (2:3) to form a series of three electrogenerated bases of successively increasing basicity. These were the radical anion, the dianion, and the radical trianion of the fullerene. Cyclic voltammograms indicated that the radical anion was capable of deprotonating the relatively strong C-H acid, ethyl nitroacetate. The weaker acid, diethyl malonate, required the stronger base C{sub 60}{sup 2{minus}} in order to observe deprotonation on the voltammetric time scale. Other weak acids that react with C{sub 60}{sup 2{minus}} include diethyl methylalonate, 2-nitropropane, and n-octanethiol. The anionic electrogenerated bases were used to carry out efficient base-catalyzed synthetic reactions. These included the C{sub 60}{sup {minus}{sm_bullet}}-catalyzed reaction of ethyl nitroacetate with ethyl acrylate and acrylonitrile to form double addition products. The dianion promoted reaction of nitromethane with ethyl acrylate to form a triple addition product in good yield, as well as the reaction of diethyl malonate with acrylonitrile to give a double addition product. In this case it was demonstrated that the fullerene probase may be recycled at least two times. The dianion was also used to catalyze the addition of n-octanethiol to styrene oxide. The reactions of still weaker acids could be promoted by the highly basic C{sub 60}{sup 3{minus}}. These included the addition of pyrrole to acrylonitrile and the Wittig-Horner reaction of diethyl benzylphosphonate with benzaldehyde.

  12. Iodide and triiodide anion complexes involving anion-π interactions with a tetrazine-based receptor.

    Science.gov (United States)

    Savastano, Matteo; Bazzicalupi, Carla; García, Celeste; Gellini, Cristina; López de la Torre, María Dolores; Mariani, Palma; Pichierri, Fabio; Bianchi, Antonio; Melguizo, Manuel

    2017-04-05

    Protonated forms of the tetrazine ligand L2 (3,6-bis(morpholin-4-ylethyl)-1,2,4,5-tetrazine) interact with iodide in aqueous solution forming relatively stable complexes (ΔG° = -11.6(4) kJ mol(-1) for HL2(+) + I(-) = (HL2)I and ΔG° = -13.4(2) kJ mol(-1) for H2L2(2+) + I(-) = [(H2L2)I](+)). When solutions of [(H2L2)I](+) are left in contact with air, crystals of the oxidation product (H2L2)2(I3)3I·4H2O are formed. Unfortunately, the low solubility of I3(-) complexes prevents the determination of their stability constants. The crystal structures of H2L2I2·H2O (1), H2L2(I3)2·2H2O (2) and (H2L2)2(I3)3I·4H2O (3) were determined by means of X-ray diffraction analyses. In all crystal structures, it was found that the interaction between I(-) and I3(-) with H2L2(2+) is dominated by anion interactions with the π electron density of the receptor. Only in the case of 1, the iodide anions involved in close anion-π interactions with the ligand tetrazine ring form an additional H-bond with the protonated morpholine nitrogen of an adjacent ligand molecule. Conversely, in crystals of 2 and 3 there are alternate segregated planes which contain only protonated ligands hydrogen-bonded to cocrystallized water molecules or I3(-) and I(-) forming infinite two-dimensional networks established through short interhalogen contacts, making these crystalline products good candidates to behave as solid conductors. In the solid complexes, the triiodide anion displays both end-on and side-on interaction modes with the tetrazine ring, in agreement with density functional theory calculations indicating a preference for the alignment of the I3(-) molecular axis with the molecular axis of the ligand. Further information about geometries and structures of triiodide anions in 2 and 3 was acquired by the analysis of their Raman spectra.

  13. Experimentally quantifying the advantages of weak-value-based metrology

    OpenAIRE

    Viza, Gerardo I.; Martínez-Rincón, Julián; Alves, Gabriel B.; Jordan, Andrew N.; Howell, John C.

    2014-01-01

    We experimentally investigate the relative advantages of implementing weak-value-based metrology versus standard methods. While the techniques outlined herein apply more generally, we measure small optical beam deflections both using a Sagnac interferometer with a monitored dark port (the weak-value-based technique), and by focusing the entire beam to a split detector (the standard technique). By introducing controlled external transverse detector modulations and transverse beam deflection mo...

  14. Graphene-Based Superconducting Weak Links in Low Magnetic Field

    Science.gov (United States)

    Mills, Scott; Kumaravadivel, Piranavan; Du, Xu

    The impact of magnetic field on Andreev reflection is studied in graphene-based superconducting weak links. We found, through studying weak links with different adhesion layers and superconducting leads (including Graphene-Ti/Au-Nb, Graphene-Ti/Pd-Nb, Graphene-V-Nb, Graphene-Ti-Nb, Graphene-Ti/Pd-NbN), that in low field (B graphene-superconductor interface. As the effective gap of the weak link approaches the intrinsic gap of the superconducting leads, a remnant of Andreev reflection can survive into the quantum Hall regime, allowing study of the interplay between the quantum Hall effect and Andreev reflection in high quality suspended graphene-superconductor weak links.

  15. Characterization and reactivity of the weakly bound complexes of the [H, N, S]{sup −} anionic system with astrophysical and biological implications

    Energy Technology Data Exchange (ETDEWEB)

    Trabelsi, T.; Ajili, Y.; Ben Yaghlane, S.; Jaidane, N.-E. [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications–LSAMA, Université de Tunis El Manar, Tunis (Tunisia); Mogren Al-Mogren, M. [Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Francisco, J. S. [Department of Chemistry and Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47906 (United States); Hochlaf, M., E-mail: hochlaf@univ-mlv.fr [Laboratoire Modélisation et Simulation Multi Echelle, Université Paris-Est, MSME UMR 8208 CNRS, 5 Blvd. Descartes, 77454 Marne-la-Vallée (France)

    2015-07-21

    We investigate the lowest electronic states of doublet and quartet spin multiplicity states of HNS{sup −} and HSN{sup −} together with their parent neutral triatomic molecules. Computations were performed using highly accurate ab initio methods with a large basis set. One-dimensional cuts of the full-dimensional potential energy surfaces (PESs) along the interatomic distances and bending angle are presented for each isomer. Results show that the ground anionic states are stable with respect to the electron detachment process and that the long range parts of the PESs correlating to the SH{sup −} + N, SN{sup −} + H, SN + H{sup −}, NH + S{sup −}, and NH{sup −} + S are bound. In addition, we predict the existence of long-lived weakly bound anionic complexes that can be formed after cold collisions between SN{sup −} and H or SH{sup −} and N. The implications for the reactivity of these species are discussed; specifically, it is shown that the reactions involving SH{sup −}, SN{sup −}, and NH{sup −} lead either to the formation of HNS{sup −} or HSN{sup −} in their electronic ground states or to autodetachment processes. Thus, providing an explanation for why the anions, SH{sup −}, SN{sup −}, and NH{sup −}, have limiting detectability in astrophysical media despite the observation of their corresponding neutral species. In a biological context, we suggest that HSN{sup −} and HNS{sup −} should be incorporated into H{sub 2}S-assisted heme-catalyzed reduction mechanism of nitrites in vivo.

  16. Experimentally quantifying the advantages of weak-value-based metrology

    Science.gov (United States)

    Viza, Gerardo I.; Martínez-Rincón, Julián; Alves, Gabriel B.; Jordan, Andrew N.; Howell, John C.

    2015-09-01

    We experimentally investigate the relative advantages of implementing weak-value-based metrology versus standard methods. While the techniques outlined herein apply more generally, we measure small optical beam deflections both using a Sagnac interferometer with a monitored dark port (the weak-value-based technique), and by focusing the entire beam to a split detector (the standard technique). By introducing controlled external transverse detector modulations and transverse beam deflection momentum modulations, we quantify the mitigation of these sources in the weak-value-based experiment versus the standard focusing experiment. The experiments are compared using a combination of deterministic and stochastic methods. In all cases, the weak-value technique performs the same or better than the standard technique by up to two orders of magnitude in precision for our parameters. We further measure the statistical efficiency of the weak-value-based technique. By postselecting on 1 % of the photons, we obtain 99 % of the available Fisher information of the beam deflection parameter.

  17. Model-based analysis of anion-exchanger positioning in direct methanol fuel cell systems

    Science.gov (United States)

    Kraus, Maik; Schröder, Daniel; Krewer, Ulrike

    2014-09-01

    In this work we present a model based study to investigate the presence of anion exchangers in direct methanol fuel cell (DMFC) systems. It is well known that environmental or fuel impurities lead to accumulation of harmful anions, such as chloride, in the system. However, due to DMFC anodic reaction, a carbonate system is present. These corbanate anions have to be taken into account for the anion exchanger design and placement as well as for the system operation strategy with and without anion exchanger, which is the objective of this study. For this purpose, the expected amount of harmful chloride ions in a DMFC system is estimated, and that of carbonate ions is calculated with a model of the carbonate system in a DMFC system. The predicition of durability and dimensions of an anion exchanger is based on a monovalent anion exchange model. The design of gas liquid separators in the DMFC system has a major influence on the amount of dissolved carbon dioxide, which is crucial for durability and dimension of a system integrated anion exchanger. Finally, feasible positions of anion exchanger in a DMFC system are elaborated to fulfill the needs for long term and stable DMFC operation.

  18. Selectivity issues in targeted metabolomics: Separation of phosphorylated carbohydrate isomers by mixed-mode hydrophilic interaction/weak anion exchange chromatography.

    Science.gov (United States)

    Hinterwirth, Helmut; Lämmerhofer, Michael; Preinerstorfer, Beatrix; Gargano, Andrea; Reischl, Roland; Bicker, Wolfgang; Trapp, Oliver; Brecker, Lothar; Lindner, Wolfgang

    2010-11-01

    Phosphorylated carbohydrates are important intracellular metabolites and thus of prime interest in metabolomics research. Complications in their analysis arise from the existence of structural isomers that do have similar fragmentation patterns in MS/MS and are hard to resolve chromatographically. Herein, we present selective methods for the liquid chromatographic separation of sugar phosphates, such as hexose and pentose phosphates, 2- and 3-phosphoglycerate, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, as well as glucosamine 1- and 6-phosphate utilizing mixed-mode chromatography with reversed-phase/weak anion-exchangers and a charged aerosol detector. The best results were obtained when the reversed-phase/weak anion-exchanger column was operated under hydrophilic interaction liquid chromatography elution conditions. The effects of various chromatographic parameters were examined and are discussed on the basis of a simple stoichiometric displacement model for explaining ion-exchange processes. Employed acidic conditions have led to the complete separation of α- and β-anomers of glucose 6-phosphate at low temperature. The anomers coeluted in a single peak at elevated temperatures (>40°C) (peak coalescence), while at intermediate temperatures on-column interconversion with a plateau in-between resolved anomer peaks was observed with apparent reaction rate constants between 0.1 and 27.8×10(-4) s(-1). Dynamic HPLC under specified conditions enabled to investigate mutarotation of phosphorylated carbohydrates, their interconversion kinetics, and energy barriers for interconversion. A complex mixture of six hexose phosphate structural isomers could be resolved almost completely.

  19. Molecular imprinting sensor based on quantum weak measurement.

    Science.gov (United States)

    Li, Dongmei; He, Qinghua; He, Yonghong; Xin, Meiguo; Zhang, Yilong; Shen, Zhiyuan

    2017-08-15

    A new type of sensing protocol, based on a high precision metrology of quantum weak measurement, was first proposed for molecularly imprinted polymers (MIP) sensor. The feasibility, sensitivity and selectivity of weak measurement based MIP (WMMIP) sensor were experimentally demonstrated with bovine serum albumin (BSA). Weak measurement system exhibits high sensitivity to the optical phase shift corresponding to the refractive index change, which is induced by the specific capture of target protein molecules with its recognition sites. The recognition process can be finally characterized by the central wavelength shift of output spectra through weak value amplification. In our experiment, we prepared BSA@MIP with modified reversed-phase microemulsion method, and coated it on the internal surface of measuring channels assembled into the Mach-Zehnder (MZ) interferometer based optical weak measurement system. The design of this home-built optical system makes it possible to detect analyte in real time. The dynamic process of the specific adsorption and concentration response to BSA from 5×10-4 to 5×10-1μg/L was achieved with a limit of detection (LOD) of 8.01×10-12g/L. This WMMIP shows superiority in accuracy, fast response and low cost. Furthermore, real-time monitoring system can creatively promote the performance of MIP in molecular analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    KAUST Repository

    Zhang, H.

    2013-08-07

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

  1. Weak anion-exchange hypercrosslinked sorbent in on-line solid-phase extraction-liquid chromatography coupling to achieve automated determination with an effective clean-up.

    Science.gov (United States)

    Fontanals, Núria; Cormack, Peter A G; Sherrington, David C; Marcé, Rosa M; Borrull, Francesc

    2010-04-23

    A mixed-mode polymeric sorbent was on-line coupled to liquid chromatography (LC) for the first time and applied to the selective solid-phase extract a group of pharmaceuticals in complex environmental water samples. The mixed-mode polymeric sorbent is a high-specific surface area hypercrosslinked polymer resin (HXLPP) in the form of monodisperse microspheres further modified with 1,2-ethylenediamine (EDA) moieties. These properties allow its application as a weak anion-exchange (WAX) sorbent in the on-line solid-phase extraction (SPE) coupling. The on-line SPE-LC method developed using the HXLPP-WAX sorbent was successfully applied to percolate a large volume of ultrapure (500 ml), river (250 ml) and effluent sewage (100 ml) water samples. In all the cases, the HXLPP-WAX resin provided near total recoveries of the most acidic compounds studied and clean chromatograms. This is because the ion-exchange interactions enable a washing step to be added to the SPE protocol that removes the compounds with weak acidic, neutral and basic properties from the sample matrix. Copyright 2010 Elsevier B.V. All rights reserved.

  2. School-Based Sexuality Education in Portugal: Strengths and Weaknesses

    Science.gov (United States)

    Rocha, Ana Cristina; Leal, Cláudia; Duarte, Cidália

    2016-01-01

    Portugal, like many other countries, faces obstacles regarding school-based sexuality education. This paper explores Portuguese schools' approaches to implementing sexuality education at a local level, and provides a critical analysis of potential strengths and weaknesses. Documents related to sexuality education in a convenience sample of 89…

  3. Synthesis and Anion Binding Properties of a Novel 1,8-dipyrrolecarbazole Schiff-base

    Directory of Open Access Journals (Sweden)

    Marina Šekutor

    2015-12-01

    Full Text Available New anion receptor N1,N8-bis[1H-pyrro-2-yl-methylidene]-3,6-dichloro-9H-carbazole-1,8-diamine (3 was synthesized and its binding properties towards anions (Cl-, Br-, AcO- and H2PO4- investigated by UV/Vis spectroscopy. In order to find the most stable structure of receptor 3, geometries of all possible isomers of 3 were optimized by the DFT/B3LYP method. It has been determined that receptor 3 forms complexes with a 1:1 stoichiometry with all the studied anions and no significant selectivity with respect to anion geometry was found. However, 1,8-dipyrrolecarbazole Schiff-base 3 binds oxoanions (H2PO4- and AcO- more strongly than spherical halogenide (Cl- and Br- anions.

  4. Anion recognition by azophenol thiourea-based chromogenic sensors: a combined DFT and molecular dynamics investigation.

    Science.gov (United States)

    Wong, Ming Wah; Xie, Huifang; Kwa, Soo Tin

    2013-01-01

    The relative binding affinities of several anions towards 2-nitroazophenol thiourea-based receptors were studied using density functional theory (DFT) in the gas phase and in chloroform solvent via PCM calculations. Both receptors have five distinctive NH and OH hydrogen donor atoms. All receptor-anion complexes are characterized by five intermolecular hydrogen bonds. The binding free energies are strongly influenced by a dielectric medium, and the solvation effect alters the trend of anion binding to the receptor. The calculated order of anion binding affinity for the receptor in chloroform, H2PO4->AcO->F->Cl->HSO4->NO3-, is in excellent accord with experimental findings. The overall order of binding affinity is attributed to the basicity of the anion, the effect of solvation, and the number of proton acceptors available. Calculations of the NMR and UV-vis spectra strongly support the experimental characterization of the receptor-anion complexes. Explicit solvent molecular dynamics simulations of selected receptor-anion complexes were also carried out. Analysis of the structural descriptors revealed that the anions were strongly bound within the binding pocket via hydrogen-bonding interactions to the five receptor protons throughout the simulation.

  5. Relationships between stream acid anion-base cation chemistry and watershed soil types on the Allegheny high plateau

    Science.gov (United States)

    Gregory P. Lewis

    1999-01-01

    The leaching of calcium and magnesium from forests by atmospherically-deposited strong acid anions (sulfate and nitrate) is evidenced in some watersheds by the positive correlation in stream water between concentrations of these base cations and acid anions.

  6. L-shaped benzimidazole fluorophores: synthesis, characterization and optical response to bases, acids and anions.

    Science.gov (United States)

    Lirag, Rio Carlo; Le, Ha T M; Miljanić, Ognjen Š

    2013-05-14

    Nine L-shaped benzimidazole fluorophores have been synthesized, computationally evaluated and spectroscopically characterized. These "half-cruciform" fluorophores respond to bases, acids and anions through changes in fluorescence that vary from moderate to dramatic.

  7. Effects of dietary strong acid anion challenge on regulation of acid-base balance in sheep

    National Research Council Canada - National Science Library

    Las, J. E; Odongo, N. E; Lindinger, M. I; AlZahal, O; Shoveller, A. K; Matthews, J. C; McBride, B. W

    2007-01-01

    ...{at}uoguelph.ca The acid-base status of the extracellular fluid is directly affected by the concentrations of strong basic cations and strong acid anions that are absorbed into the bloodstream from the diet...

  8. Potentiometric response and mechanism of anionic recognition of heterocalixarene-based ion selective electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Shishkanova, T.V. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)]. E-mail: tatiana.shishkanova@vscht.cz; Sykora, D. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Sessler, J.L. [Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712-0615 (United States); Kral, V. [Department of Analytical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2007-03-28

    The ion selective electrode (ISE)-based potentiometric approach is shown to be an effective means of characterizing the anion recognition sites in the molecular receptor calix[2]pyridino[2]pyrrole (CPP). In particular, potentiometric pH-measurements involving the use of experimental PVC-membranes based on CPP revealed the existence of both mono- and diprotonated forms of the receptor under readily accessible conditions. Based on these analyses, apparent surface protonation constants for this heterocalixarene were found to lie between 8.5-8.9 (pK {sub B1}) and 3.3-3.8 (pK {sub B2}). CPP was found to interact with targeted anionic analytes based on both coulombic and hydrogen bond interactions, as inferred from varying the kinds of ionic sites present within the membrane phase. Potentiometric selectivity studies revealed that CPP preferred 'Y-shaped' anions (e.g. acetate, lactate, benzoate) over spherical anions (e.g. fluoride and chloride), fluoride over chloride within the set of spherical anions, and the ortho-isomer over the corresponding meta- and para-isomers in the case of hydroxybenzoate (salicylate and congeners). In the context of this study, the advantages of potentiometric determinations of acetylsalicylic acid using optimized PVC-membranes based on CPP relative to more conventional PVC-membrane ISEs based on traditional anion exchanger were also demonstrated.

  9. Human action recognition based on estimated weak poses

    Science.gov (United States)

    Gong, Wenjuan; Gonzàlez, Jordi; Roca, Francesc Xavier

    2012-12-01

    We present a novel method for human action recognition (HAR) based on estimated poses from image sequences. We use 3D human pose data as additional information and propose a compact human pose representation, called a weak pose, in a low-dimensional space while still keeping the most discriminative information for a given pose. With predicted poses from image features, we map the problem from image feature space to pose space, where a Bag of Poses (BOP) model is learned for the final goal of HAR. The BOP model is a modified version of the classical bag of words pipeline by building the vocabulary based on the most representative weak poses for a given action. Compared with the standard k-means clustering, our vocabulary selection criteria is proven to be more efficient and robust against the inherent challenges of action recognition. Moreover, since for action recognition the ordering of the poses is discriminative, the BOP model incorporates temporal information: in essence, groups of consecutive poses are considered together when computing the vocabulary and assignment. We tested our method on two well-known datasets: HumanEva and IXMAS, to demonstrate that weak poses aid to improve action recognition accuracies. The proposed method is scene-independent and is comparable with the state-of-art method.

  10. A weak blind signature scheme based on quantum cryptography

    Science.gov (United States)

    Wen, Xiaojun; Niu, Xiamu; Ji, Liping; Tian, Yuan

    2009-02-01

    In this paper, we present a weak blind signature scheme based on the correlation of EPR (Einstein-Padolsky-Rosen) pairs. Different from classical blind signature schemes and current quantum signature schemes, our quantum blind signature scheme could guarantee not only the unconditionally security but also the anonymity of the message owner. To achieve that, quantum key distribution and one-time pad are adopted in our scheme. Experimental analysis proved that our scheme have the characteristics of non-counterfeit, non-disavowal, blindness and traceability. It has a wide application to E-payment system, E-government, E-business, and etc.

  11. Ion pair dissociation effects of aza-based anion receptors on lithium salts in polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.Q.; Lee, H.S.; Xiang, C.; McBreen, J. [Brookhaven National Lab., Upton, NY (United States); Choi, L.S. [Naval Research Lab., Washington, DC (United States); Okamoto, Y. [Polytechnic Univ., Brooklyn, NY (United States)

    1996-12-31

    The addition of aza-based anion receptors greatly increases the conductivity of polymer electrolytes based on LiCl and KI complexes with poly(ethylene oxide) (PEO). In some cases the conductivity increase is more than two orders of magnitude. Also the addition of the anion acceptors imparts a rubber like consistency to the normally stiff PEO salt films. Ion-ion, ion-polymer and anion-complex interactions were studied using Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the K and Cl K edges and at the I L{sub I} edge. The NEXAFS results show that Cl{sup {minus}} and I{sup {minus}} anions are complexed with the nitrogen groups of the anion receptors. The degree of complexation is related the chain length of the complexing agent and the number of R{double_bond}CF{sub 3}SO{sub 2} groups that are used to substitute for the amine hydrogen atoms in these aza-ether compounds. NEXAFS spectra at potassium K edge provide supplemental evidence for the ion pair dissociation effects of the anion receptors. The results show that dissociated K{sup +} cations are complexed with oxygen atoms of the PEO chains.

  12. Probing electron density of H-bonding between cation-anion of imidazolium-based ionic liquids with different anions by vibrational spectroscopy.

    Science.gov (United States)

    Gao, Yan; Zhang, Liqun; Wang, Yong; Li, Haoran

    2010-03-04

    Attenuated total reflection infrared spectroscopy and density functional theory calculation have been employed to study the spectral properties of imidazolium-based ionic liquids (ILs) with different anions. ILs based on 1-butyl-3-methylimidazolium cation with different anions, OH(-), CF(3)CO(2)(-), HSO(4)(-), H(2)PO(4)(-), Cl(-), PF(6)(-), and BF(4)(-), are investigated in the present work. It has been shown that the C(2)-H stretching vibration of the imidazolium ring is closely related to the electron density of H-bonding between the two closest cations and anions for pure ILs. The electron density of H-bonding between cation and anion with different anions decreases in the order [OH](-) > [H(2)PO(4)](-) > [HSO(4)](-) > [CF(3)CO(2)](-) > [Cl](-) > [BF(4)](-) > [PF(6)](-). For aqueous ILs, with increasing water content, the aromatic C-H stretching vibration of the imidazolium cation showed systematic blue-shifts. Especially for BmimOH, the nu(C(2))(-H) undergoes a drastic blue-shift by 58 cm(-1), suggesting that the formation of the strong hydrogen bonds O-H...O may greatly weaken the electron density of H-bonding between the cation and anion of ILs.

  13. Separation of small inorganic anions using methacrylate-based anion-exchange monolithic column prepared by low temperature UV photo-polymerization.

    Science.gov (United States)

    Takahashi, Mutsumi; Hirano, Tomohiko; Kitagawa, Shinya; Ohtani, Hajime

    2012-04-06

    A methacrylate-based anion-exchange monolithic column was prepared by a single-step UV photo-copolymerization of [2-(methacryloyloxy)ethyl]-trimethyl ammonium chloride, butylmethacrylate, and ethylene dimethacrylate at a low temperature of -15 °C. The anion-exchange column exhibited good separation efficiency for the small inorganic anions of NO(2)(-), Br(-), NO(3)(-), and I(-) in the isocratic mode. Under the conditions optimized using a mobile phase of 50% ACN containing 100mM of NaCl, the theoretical plate heights of the anions were within the range of 12.2-15.6 μm (N, 64,000-82,000 m(-1); k, 0.2-1.6); and a value of 9.4 μm (N, 110,000 m(-1)) was achieved for t(0). The flow resistance of the column was acceptably low with a permeability of 2.7 × 10(-13) m(2). Fast gradient elution at a flow rate of 32 mm/s resulted in rapid and precise separation of the inorganic anions of IO(3)(-), NO(2)(-), Br(-), NO(3)(-), and I(-) within 20s. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. "Naked-eye" screening of metal-based chemosensors for biologically important anions.

    Science.gov (United States)

    Männel-Croisé, Christine; Meister, Christian; Zelder, Felix

    2010-11-15

    A two-step "naked-eye" screening of selective metal-based chemosensors for biologically important anions such as cyanide, phosphate, and oxalate from commercially available metal indicators and metal ions has been developed. Applications in food safety control have been demonstrated.

  15. Proton affinities of anionic bases: Trends across the periodic table, structural effects, and DFT validation

    NARCIS (Netherlands)

    Swart, M.; Bickelhaupt, F.M.

    2006-01-01

    We have carried out an extensive exploration of the gas-phase basicity of archetypal anionic bases across the periodic system using the generalized gradient approximation of density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing proton

  16. Ectomycorrhizal fungi and Pinus sylvestris: aluminium toxicity, base cation deficiencies and exudation of organic anions.

    NARCIS (Netherlands)

    Schöll, van L.

    2006-01-01

    Keywords: aluminium (Al), base cations, BC:Alratio, magnesium (Mg), organic anions, oxalate, malonate, ectomycorrhizal fungi, Paxillus involutus, Pinus sylvestris (Scots pine)The finding of microscopic-small tunnels in mineral grains

  17. [Nutrition, acid-base metabolism, cation-anion difference and total base balance in humans].

    Science.gov (United States)

    Mioni, R; Sala, P; Mioni, G

    2008-01-01

    The relationship between dietary intake and acid-base metabolism has been investigated in the past by means of the inorganic cation-anion difference (C(+)(nm)-A(-)(nm)) method based on dietary ash-acidity titration after the oxidative combustion of food samples. Besides the inorganic components of TA (A(-)(nm)-C(+)(nm)), which are under renal control, there are also metabolizable components (A(-)(nm)-C(+)(nm)) of TA, which are under the control of the intermediate metabolism. The whole body base balance, NBb(W), is obtained only by the application of C(+)(nm)-A(-)(nm) to food, feces and urine, while the metabolizable component (A(-)(nm)-C(+)(nm)) is disregarded. A novel method has been subsequently suggested to calculate the net balance of fixed acid, made up by the difference between the input of net endogenous acid production: NEAP = SO(4)(2-)+A(-)(m)-(C(+)(nm)-A(-)(nm)), and the output of net acid excretion: NAE = TA + NH(4)(+) - HCO(3)(-). This approach has been criticized because 1) it includes metabolizable acids, whose production cannot be measured independently; 2) the specific control of metabolizable acid and base has been incorrectly attributed to the kidney; 3) the inclusion of A-m in the balance input generates an acid overload; 4) the object of measurement in making up a balance has to be the same, a condition not fulfilled as NEAP is different from NAE. Lastly, by rearranging the net balance of the acid equation, the balance of nonmetabolizable acid equation is obtained. Therefore, any discrepancy between these two equations is due to the inaccuracy in the urine measurement of metabolizable cations and/or anions.

  18. Potentiometric anion selectivity of polymer-membrane electrodes based on cobalt, chromium, and aluminum salens

    Energy Technology Data Exchange (ETDEWEB)

    Badr, Ibrahim H.A. [Department of Chemistry, Faculty of Science, Ain Shams University, P.O. Box 11566, Cairo (Egypt)]. E-mail: ibadr1@yahoo.com

    2006-06-16

    Metallo-salens of cobalt(II) (Co-Sal), chromium(III) (Cr-Sal), and aluminum(III) (Al-Sal) are used as the active ionophores within plasticized poly(vinyl chloride) membranes. It is shown that central metal-ion plays a critical role in directing the ionophore selectivity. Polymer-membrane electrodes based on Co-Sal, Cr-Sal, and Al-Sal are demonstrated to exhibit enhanced responses and selectivity toward nitrite/thiocyanate, thiocyanate, and fluoride anions, respectively. The improved anion selectivity of the three ionophore systems is shown to deviate significantly from the classical Hofmeister pattern that is based only on ion lipophilicity. For example, optimized membrane electrodes for nitrite ion based on Co-Sal exhibit logK{sub Nitrite,Anion}{sup pot} values of -5.22, -4.66, -4.48, -2.5 towards bromide, perchlorate, nitrate, and iodide anions, respectively. Optimized membrane electrodes based on Co-Sal and Cr-Sal show near-Nernstian responses towards nitrite (-57.9+/-0.9mV/decade) and thiocyanate (-56.9+/-0.8mV/decade), respectively, with fast response and recovery times. In contrast, Al-Sal based membrane electrodes respond to fluoride ion in a super-Nernstian (-70+/-3mV/decade) and nearly an irreversible mode. The operative response mechanism of Co-Sal, Cr-Sal, and Al-Sal membrane electrodes is examined using the effect of added ionic sites on the potentiometric response characteristics. It is demonstrated that addition of lipophilic anionic sites to membrane electrodes based on the utilized metallo-salens enhances the selectivity towards the primary ion, while addition of cationic sites resulted in Hofmeister selectivity patterns suggesting that the operative response mechanism is of the charged carrier type. Electron spin resonance (ESR) data indicates that Co(II) metal-ion center of Co-Sal ionophore undergoes oxidation to Co(III). This process leads to formation of a charged anion-carrier that is consistent with the response behavior obtained for Co

  19. Synthesis and evaluation of simple naked-eye colorimetric chemosensors for anions based on azo dye-thiosemicarbazones

    Science.gov (United States)

    Radchatawedchakoon, Widchaya; Sangsuwan, Withsakorn; Kruanetr, Senee; Sakee, Uthai

    2014-03-01

    A series of novel, highly selective azo dye-thiosemicarbazones based anion sensors (3e-f) have been synthesized from the condensation reaction between thiosemicarbazide and six different azo salicylaldehydes. The structure of the sensors was confirmed by spectroscopic methods. The selectivity and sensitivity in the recognition for acetate anion over other anions such as fluoride, chloride, iodide and dihydrogenphosphate anions were determined by naked-eyes and UV-vis spectra. The color of the solution containing sensor had an obvious change from light yellow to orange only after the addition of acetate anion in aqueous solution (water/dimethylsulfoxide, 7:3, v/v) while other anions did not cause obvious color change. The anion recognition property of the receptor via proton-transfer is monitored by UV-vis titration and 1H NMR spectroscopy. Under condition in aqueous solution of sensor 3e (water/dimethylsulfoxide, 7:3, v/v), linearity range for the quantification of acetate anion was 1-22 μM and limit of detection (LOD) of acetate anion was 0.71 μM.

  20. Policy-based benchmarking of weak heaps and their relatives

    DEFF Research Database (Denmark)

    Bruun, Asger; Edelkamp, Stefan; Katajainen, Jyrki

    2010-01-01

    ), and a run-relaxed weak queue that of both insert and decrease to O(1). As competitors to these structures, we considered a binary heap, a Fibonacci heap, and a pairing heap. Generic programming techniques were heavily used in the code development. For benchmarking purposes we developed several component...

  1. On the physical origin of the cation-anion intermediate bond in ionic liquids Part I. Placing a (weak) hydrogen bond between two charges.

    Science.gov (United States)

    Lehmann, Sebastian B C; Roatsch, Martin; Schöppke, Matthias; Kirchner, Barbara

    2010-07-21

    the counterions in imidazolium-based ionic liquids. While geometry and charge analysis provides attributes of weak (blue-shifted) hydrogen bonds, large bond elongations accompanied by red-shifts are obtained for the ion pairs investigated. This can be understood by the simple fact that these imidazolium-based ionic liquid ion pairs constitute weak hydrogen bonds placed between two delocalized charges.

  2. Anionic magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid for DNA base discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Khadsai, Sudarat; Rutnakornpituk, Boonjira [Naresuan University, Department of Chemistry and Center of Excellence in Biomaterials, Faculty of Science (Thailand); Vilaivan, Tirayut [Chulalongkorn University, Department of Chemistry, Organic Synthesis Research Unit, Faculty of Science (Thailand); Nakkuntod, Maliwan [Naresuan University, Department of Biology, Faculty of Science (Thailand); Rutnakornpituk, Metha, E-mail: methar@nu.ac.th [Naresuan University, Department of Chemistry and Center of Excellence in Biomaterials, Faculty of Science (Thailand)

    2016-09-15

    Magnetite nanoparticles (MNPs) were surface modified with anionic poly(N-acryloyl glycine) (PNAG) and streptavidin for specific interaction with biotin-conjugated pyrrolidinyl peptide nucleic acid (PNA). Hydrodynamic size (D{sub h}) of PNAG-grafted MNPs varied from 334 to 496 nm depending on the loading ratio of the MNP to NAG in the reaction. UV–visible and fluorescence spectrophotometries were used to confirm the successful immobilization of streptavidin and PNA on the MNPs. About 291 pmol of the PNA/mg MNP was immobilized on the particle surface. The PNA-functionalized MNPs were effectively used as solid supports to differentiate between fully complementary and non-complementary/single-base mismatch DNA using the PNA probe. These novel anionic MNPs can be efficiently applicable for use as a magnetically guidable support for DNA base discrimination.Graphical Abstract.

  3. Structure of the green fluorescent protein NowGFP with an anionic tryptophan-based chromophore.

    Science.gov (United States)

    Pletnev, Vladimir Z; Pletneva, Nadya V; Sarkisyan, Karen S; Mishin, Alexander S; Lukyanov, Konstantin A; Goryacheva, Ekaterina A; Ziganshin, Rustam H; Dauter, Zbigniew; Pletnev, Sergei

    2015-08-01

    A green-emitting fluorescent variant, NowGFP, with a tryptophan-based chromophore (Thr65-Trp66-Gly67) was recently developed from the cyan mCerulean by introducing 18 point mutations. NowGFP is characterized by bright green fluorescence at physiological and higher pH and by weak cyan fluorescence at low pH. Illumination with blue light induces irreversible photoconversion of NowGFP from a green-emitting to a cyan-emitting form. Here, the X-ray structures of intact NowGFP at pH 9.0 and pH 4.8 and of its photoconverted variant, NowGFP_conv, are reported at 1.35, 1.18 and 2.5 Å resolution, respectively. The structure of NowGFP at pH 9.0 suggests the anionic state of Trp66 of the chromophore to be the primary cause of its green fluorescence. At both examined pH values Trp66 predominantly adopted a cis conformation; only ∼ 20% of the trans conformation was observed at pH 4.8. It was shown that Lys61, which adopts two distinct pH-dependent conformations, is a key residue playing a central role in chromophore ionization. At high pH the side chain of Lys61 forms two hydrogen bonds, one to the indole N atom of Trp66 and the other to the carboxyl group of the catalytic Glu222, enabling an indirect noncovalent connection between them that in turn promotes Trp66 deprotonation. At low pH, the side chain of Lys61 is directed away from Trp66 and forms a hydrogen bond to Gln207. It has been shown that photoconversion of NowGFP is accompanied by decomposition of Lys61, with a predominant cleavage of its side chain at the C(γ)-C(δ) bond. Lys61, Glu222, Thr203 and Ser205 form a local hydrogen-bond network connected to the indole ring of the chromophore Trp66; mutation of any of these residues dramatically affects the spectral properties of NowGFP. On the other hand, an Ala150Val replacement in the vicinity of the chromophore indole ring resulted in a new advanced variant with a 2.5-fold improved photostability.

  4. A strategy for the preparation of thioantimonates based on the concept of weak acids and corresponding strong bases.

    Science.gov (United States)

    Anderer, Carolin; Delwa de Alarcón, Natalie; Näther, Christian; Bensch, Wolfgang

    2014-12-15

    By following a new synthetic approach, which is based on the in situ formation of a basic medium by the reaction between the strong base Sb(V)S4 (3-) and the weak acid H2 O, it was possible to prepare three layered thioantimonate(III) compounds of composition [TM(2,2'-bipyridine)3 ][Sb6 S10 ] (TM=Ni, Fe) and [Ni(4,4'-dimethyl-2,2'-bipyridine)3 ][Sb6 S10 ] under hydrothermal conditions featuring two different thioantimonate(III) network topologies. The antimony source, Na3 SbS4 ⋅ 9 H2 O, undergoes several decomposition reactions and produces the Sb(III) S3 species, which condenses to generate the layered anion. The application of transition-metal complexes avoids crystallization of dense phases. The reactions are very fast compared to conventional hydrothermal/solvothermal syntheses and are much less sensitive to changes of the reaction parameters. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Use of weak ion association in the separation of inorganic anions by capillary electrophoresis with specific application to simultaneous-trace determination of bromate and iodate in drinking water

    Directory of Open Access Journals (Sweden)

    Julius Mbuna

    2008-04-01

    Full Text Available In this work weak ion association was used to effect selectivity and detection of inorganic anions with environmental or health significance by capillary electropheresis, CE. Tetrabutylammonium ion was used as a pairing anion to separate mixtures containing closely or co-migrating inorganic anions at pHs 3.8 and pH 7. Despite taking a longer analysis time, better resolution is achieved at pH 7 than 3.8. Trace level of bromate and iodate present in drinking water were determined after online pre-concentration by field enhanced sample injection (FESI technique. Consequently an internal standard (SCN- was employed, which entailed the use of tetrabutylammonium ion as a pairing cation to resolve the internal standard from a co-migrating broad peak. The LODs (S/N = 3 were 7.8 x 10-10 M (10 ppb and 1.2 x 10-9 M (0.21 ppb for bromate and iodate, respectively. The method was subsequently used to determine bromate and iodate levels in drinking water.

  6. Anion recognition by simple chromogenic and chromo-fluorogenic salicylidene Schiff base or reduced-Schiff base receptors.

    Science.gov (United States)

    Dalapati, Sasanka; Jana, Sankar; Guchhait, Nikhil

    2014-08-14

    This review contains extensive application of anion sensing ability of salicylidene type Schiff bases and their reduced forms having various substituents with respect to phenolic OH group. Some of these molecular systems behave as receptor for recognition or sensing of various anions in organic or aqueous-organic binary solvent mixture as well as in the solid supported test kits. Development of Schiff base or reduced Schiff base receptors for anion recognition event is commonly based on the theory of hydrogen bonding interaction or deprotonation of phenolic -OH group. The process of charge transfer (CT) or inhibition of excited proton transfer (ESIPT) or followed by photo-induced electron transfer (PET) lead to naked-eye color change, UV-vis spectral change, chemical shift in the NMR spectra and fluorescence spectral modifications. In this review we have tried to discuss about the anion sensing properties of Schiff base or reduced Schiff base receptors. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Colorimeric and fluorescence ON-OFF probe for acetate anion based on thiourea derivative: theory and experiment.

    Science.gov (United States)

    Shang, Xuefang; Tian, Shuanbao; Xi, Nankai; Li, Yue; Liang, Dong; Liu, Yun; Yin, Zhenya; Zhang, Jinlian; Xu, Xiufang

    2013-02-15

    Based on thiourea moiety, three colorimetric and fluorescent anion probes have been synthesized. Results indicated the probe 1 containing p-NO(2) group showed the strongest binding ability for AcO(-) among the anions tested (F(-), AcO(-), H(2)PO(4)(-), Cl(-), Br(-), I(-)), which was not influenced by the existence of other anions. The interaction of host-guest was accompanied with a dramatic color change from colorless to orange. However, the addition of various anions did not cause noticeable spectral response of the probes (2 and 3) containing o, m-NO(2) groups. Theoretical investigation demonstrated the electron transition of the highest LUMO aroused the red-shift phenomenon in UV-vis spectra of 1-anion. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Interaction and dynamics of ionic liquids based on choline and amino acid anions

    Energy Technology Data Exchange (ETDEWEB)

    Campetella, M.; Bodo, E., E-mail: enrico.bodo@uniroma1.it; Caminiti, R., E-mail: ruggero.caminiti@uniroma1.it; Martino, A.; Gontrani, L. [Department of Chemistry, University of Rome “La Sapienza,” Rome (Italy); D’Apuzzo, F.; Lupi, S. [Department of Physics, University of Rome “La Sapienza,” Rome (Italy)

    2015-06-21

    The combination of amino acid anions with the choline cation gives origin to a new and potentially important class of organic ionic liquids that might represent a viable and bio-compatible alternative with respect to the traditional ones. We present here a detailed study of the bulk phase of the prototype system composed of the simplest amino acid (alanine) anion and the choline cation, based on ab initio and classical molecular dynamics. Theoretical findings have been validated by comparing with accurate experimental X-ray diffraction data and infrared spectra. We find that hydrogen bonding (HB) features in these systems are crucial in establishing their local geometric structure. We have also found that these HBs once formed are persistent and that the proton resides exclusively on the choline cation. In addition, we show that a classical force field description for this particular ionic liquid can be accurately performed by using a slightly modified version of the generalized AMBER force field.

  9. Green fluorescent protein with anionic tryptophan-based chromophore and long fluorescence lifetime.

    Science.gov (United States)

    Sarkisyan, Karen S; Goryashchenko, Alexander S; Lidsky, Peter V; Gorbachev, Dmitry A; Bozhanova, Nina G; Gorokhovatsky, Andrey Yu; Pereverzeva, Alina R; Ryumina, Alina P; Zherdeva, Victoria V; Savitsky, Alexander P; Solntsev, Kyril M; Bommarius, Andreas S; Sharonov, George V; Lindquist, Jake R; Drobizhev, Mikhail; Hughes, Thomas E; Rebane, Aleksander; Lukyanov, Konstantin A; Mishin, Alexander S

    2015-07-21

    Spectral diversity of fluorescent proteins, crucial for multiparameter imaging, is based mainly on chemical diversity of their chromophores. Recently we have reported, to our knowledge, a new green fluorescent protein WasCFP-the first fluorescent protein with a tryptophan-based chromophore in the anionic state. However, only a small portion of WasCFP molecules exists in the anionic state at physiological conditions. In this study we report on an improved variant of WasCFP, named NowGFP, with the anionic form dominating at 37°C and neutral pH. It is 30% brighter than enhanced green fluorescent protein (EGFP) and exhibits a fluorescence lifetime of 5.1 ns. We demonstrated that signals of NowGFP and EGFP can be clearly distinguished by fluorescence lifetime in various models, including mammalian cells, mouse tumor xenograft, and Drosophila larvae. NowGFP thus provides an additional channel for multiparameter fluorescence lifetime imaging microscopy of green fluorescent proteins. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Highly Conductive Anion-Exchange Membranes from Microporous Tröger's Base Polymers.

    Science.gov (United States)

    Yang, Zhengjin; Guo, Rui; Malpass-Evans, Richard; Carta, Mariolino; McKeown, Neil B; Guiver, Michael D; Wu, Liang; Xu, Tongwen

    2016-09-12

    The development of polymeric anion-exchange membranes (AEMs) combining high ion conductivity and long-term stability is a major challenge for materials chemistry. AEMs with regularly distributed fixed cationic groups, based on the formation of microporous polymers containing the V-shape rigid Tröger's base units, are reported for the first time. Despite their simple preparation, which involves only two synthetic steps using commercially available precursors, the polymers provide AEMs with exceptional hydroxide conductivity at relatively low ion-exchange capacity, as well as a high swelling resistance and chemical stability. An unprecedented hydroxide conductivity of 164.4 mS cm(-1) is obtained at a relatively a low ion-exchange capacity of 0.82 mmol g(-1) under optimal operating conditions. The exceptional anion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid anion transport. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Topic Detection Based on Weak Tie Analysis: A Case Study of LIS Research

    Directory of Open Access Journals (Sweden)

    Ling Wei

    2016-11-01

    Full Text Available Purpose: Based on the weak tie theory, this paper proposes a series of connection indicators of weak tie subnets and weak tie nodes to detect research topics, recognize their connections, and understand their evolution. Design/methodology/approach: First, keywords are extracted from article titles and preprocessed. Second, high-frequency keywords are selected to generate weak tie co-occurrence networks. By removing the internal lines of clustered sub-topic networks, we focus on the analysis of weak tie subnets' composition and functions and the weak tie nodes' roles. Findings: The research topics' clusters and themes changed yearly; the subnets clustered with technique-related and methodology-related topics have been the core, important subnets for years; while close subnets are highly independent, research topics are generally concentrated and most topics are application-related; the roles and functions of nodes and weak ties are diversified. Research limitations: The parameter values are somewhat inconsistent; the weak tie subnets and nodes are classified based on empirical observations, and the conclusions are not verified or compared to other methods. Practical implications: The research is valuable for detecting important research topics as well as their roles, interrelations, and evolution trends. Originality/value: To contribute to the strength of weak tie theory, the research translates weak and strong ties concepts to co-occurrence strength, and analyzes weak ties' functions. Also, the research proposes a quantitative method to classify and measure the topics' clusters and nodes.

  12. A REVIEW ON ACID BASE STATUS IN DAIRY COWS: IMPLICATIONS OF DIETARY CATION-ANION BALANCE

    Directory of Open Access Journals (Sweden)

    D. Afzaal, M. Nisa, M. A. Khan and M. Sarwar

    2004-10-01

    Full Text Available The acid base status of a dairy cow is maintained within a narrow range. The key mechanisms involving blood, cells and lungs, perform this function. Although other minerals have an impact on acid base metabolism, the minerals used in dietary cation-anion balance (DCAB namely sodium (Na, potassium (K and chloride (Cl have the greatest effect. Hence, acid base status implicates other biological functions of dairy cows. Low DCAB prepartum reduces the incidence of milk fever and increases the productivity by simmering down the severity of hypocalcaemia. High DCAB diets have proved to increase dry mater and water intake and production and to mitigate the effects of heat stress.

  13. Can the tricyanomethanide anion improve CO2 absorption by acetate-based ionic liquids?

    Science.gov (United States)

    Lepre, L F; Szala-Bilnik, J; Pison, L; Traïkia, M; Pádua, A A H; Ando, R A; Costa Gomes, M F

    2017-05-17

    Carbon dioxide absorption by mixtures of two ionic liquids with a common cation-1-butyl-3-methylimidazolium acetate, [C4C1Im][OAc], and 1-butyl-3-methylimidazolium tricyanomethanide, [C4C1Im][C(CN)3]-was determined experimentally at pressures below atmospheric pressure as a function of temperature between 303 K and 343 K, and at 303 K as a function of pressure up to 10 bar. It is observed that the absorption of carbon dioxide decreases with increasing tricyanomethanide anion concentration and with increasing temperature, showing a maximum of 0.4 mole fraction of carbon dioxide in pure [C4C1Im][OAc] at 303 K. At this temperature, the CO2 absorption in the mixtures [C4C1Im][OAc](1-x)[C(CN)3]x is approximately the mole-fraction average of that in the pure ionic liquids. By applying an appropriate thermodynamic treatment, after identification of the species in solution, it was possible to calculate both the equilibrium constant, Keq, and Henry's law constant, KH, in the different mixtures studied thus obtaining an insight into the relative contribution of chemical and physical absorption of the gas. It is shown that chemical sorption proceeds through a 1 : 2 stoichiometry between CO2 and acetate-based ionic liquid. The presence of the C(CN)3- anion does not significantly affect the chemical reaction of the gas with the solvent (Keq = 75 ± 2 at 303 K) but leads to lower Henry's law constants (from KH = 77.8 ± 0.6 bar to KH = 49.5 ± 0.5 bar at 303 K), thus pointing towards larger physical absorption of the gas. The tricyanomethanide anion considerably improves the mass transfer by increasing the fluidity of the absorbent as proven by the larger diffusivities of all the ions when the concentration of the C(CN)3- anion increases in the mixtures.

  14. Virtually-synchronous communication based on a weak failure suspector

    Science.gov (United States)

    Schiper, Andre; Ricciardi, Aleta

    1993-01-01

    Failure detectors (or, more accurately Failure Suspectors (FS)) appear to be a fundamental service upon which to build fault-tolerant, distributed applications. This paper shows that a FS with very weak semantics (i.e., that delivers failure and recovery information in no specific order) suffices to implement virtually-synchronous communication (VSC) in an asynchronous system subject to process crash failures and network partitions. The VSC paradigm is particularly useful in asynchronous systems and greatly simplifies building fault-tolerant applications that mask failures by replicating processes. We suggest a three-component architecture to implement virtually-synchronous communication: (1) at the lowest level, the FS component; (2) on top of it, a component (2a) that defines new views; and (3) a component (2b) that reliably multicasts messages within a view. The issues covered in this paper also lead to a better understanding of the various membership service semantics proposed in recent literature.

  15. [Disorders of the acid-base balance and the anion gap].

    Science.gov (United States)

    Kimmel, Martin; Alscher, Mark Dominik

    2016-10-01

    The regulation of the acid-base balance and pH is critical for the organism. The most important buffer system is CO2 / HCO3(-). The kidney controls systemic bicarbonate and therefore the metabolic regulation and the lung is relevant for respiratory regulation by an effective CO2 elimination. There are four acid-base disorders with two metabolic and two respiratory disorders (acidosis and alkalosis). The anion gap enables a further workup of metabolic acidosis. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Intramolecular proton transfer through the adjoining π-conjugated system in Shiff base: Application for colorimetric sensing of fluoride anion

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xudong, E-mail: 081022009@fudan.edu.cn [College of Chemistry and Material Sciences, Hebei Normal University, Yuhua Road 113, Shijiazhuang 050024 (China); College of Science and Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Zhang, Ping [College of Chemistry and Material Sciences, Hebei Normal University, Yuhua Road 113, Shijiazhuang 050024 (China); Li, Yajuan; Zhen, Xiaoli; Geng, Lijun; Wang, Yanqiu [College of Science and Hebei Research Center of Pharmaceutical and Chemical Engineering, Hebei University of Science and Technology, Yuhua Road 70, Shijiazhuang 050080 (China); Ma, Zichuan, E-mail: ma7405@hebtu.edu.cn [College of Chemistry and Material Sciences, Hebei Normal University, Yuhua Road 113, Shijiazhuang 050024 (China)

    2014-07-01

    In this paper, a new kind of phenol-based chemsensor L2 comprised of a Schiff base and azo groups was rationally designed and synthesized. It could selectively recognize fluoride anion among tested anions such as F{sup −}, AcO{sup −}, H{sub 2}PO{sub 4}{sup −}, Cl{sup −}, Br{sup −}, and I{sup −} with obvious color changes from yellow to fuchsia. The intramolecular PT (proton transfer) in L1 and L2 was responsible for the sensing ability, which was certified by the {sup 1}H NMR and Uv–vis experiments. - Highlights: • The phenol derivative L2 could selectively sense F{sup −} among test anions. • Intramolecular proton transfer happened when L2 was bonded with F{sup −}. • It is the first antipyrine-based anion receptor.

  17. Radiolytic preparation of ETFE and PFA based anion exchange membranes for alkaline fuel cell

    Science.gov (United States)

    Ko, Beom-Seok; Sohn, Joon-Yong; Nho, Young-Chang; Shin, Junhwa

    2011-11-01

    In this study, a versatile monomer, vinylbenzyl chloride (VBC) was radiolytically grafted onto a partially fluorinated ETFE and perfluorinated polymer PFA films. The VBC grafted films were treated with trimethylamine to prepare the alkaline anion exchange membranes (AAEMs). No significant differences in the ion exchange capacities and water uptakes were observed between the ETFE and PFA based AAEMs with similar degree of grafting (DOG). However, the distribution patterns of the graft chains over the cross-section of the ETFE and PFA based AAEMs were found to be quite different; the even distribution was observed from the ETFE based AAEMs while the uneven distribution was observed from the PFA based AAEMs. It was also found that the PFA based AAEMs have the higher ionic conductivity and chemical stability, compared to the ETFE based AAEMs.

  18. Chlorine Anion Encapsulation by Molecular Capsules Based on Cucurbit[5]uril and Decamethylcucurbit[5]uril

    OpenAIRE

    Zhu Tao; Sai-Feng Xue; Qian-Jiang Zhu; Yun-Qian Zhang

    2007-01-01

    Three barrel-shaped artificial molecular capsules 1-3, based on normal cucurbit[5]uril (Q[5]) and decamethylcucurbit[5]uril (Me10Q[5]), were synthesized and structurally characterized by single-crystal X-ray diffraction. Encapsulation of a chlorine anion in the cavity of a Q[5] or Me10Q[5] to form closed a molecular capsule with the coordinated metal ions or coordinated metal ions and water molecules in the crystal structures of these compounds is common. The three complexes [Pr2(C30H30N20O10...

  19. Effect of nucleobase sequence on the proton-transfer reaction and stability of the guanine-cytosine base pair radical anion.

    Science.gov (United States)

    Chen, Hsing-Yin; Yeh, Shu-Wen; Hsu, Sodio C N; Kao, Chai-Lin; Dong, Teng-Yuan

    2011-02-21

    The formation of base pair radical anions is closely related to many fascinating research fields in biology and chemistry such as radiation damage to DNA and electron transport in DNA. However, the relevant knowledge so far mainly comes from studies on isolated base pair radical anions, and their behavior in the DNA environment is less understood. In this study, we focus on how the nucleobase sequence affects the properties of the guanine-cytosine (GC) base pair radical anion. The energetic barrier and reaction energy for the proton transfer along the N(1)(G)-H···N(3)(C) hydrogen bond and the stability of GC˙(-) (i.e., electron affinity of GC) embedded in different sequences of base-pair trimer were evaluated using density functional theory. The computational results demonstrated that the presence of neighboring base pairs has an important influence on the behavior of GC˙(-) in the gas phase. The excess electron was found to be localized on the embedded GC and the charge leakage to neighboring base pairs was very minor in all of the investigated sequences. Accordingly, the sequence behavior of the proton-transfer reaction and the stability of GC˙(-) is chiefly governed by electrostatic interactions with adjacent base pairs. However, the effect of base stacking, due to its electrostatic nature, is severely screened upon hydration, and thus, the sequence dependence of the properties of GC˙(-) in aqueous environment becomes relatively weak and less than that observed in the gas phase. The effect of geometry relaxation associated with neighboring base pairs as well as the possibility of proton transfer along the N(2)(G)-H···O(2)(C) channel have also been investigated. The implications of the present findings to the electron transport and radiation damage of DNA are discussed.

  20. Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing

    Directory of Open Access Journals (Sweden)

    Karelle Aiken

    2018-02-01

    Full Text Available Detailed Nuclear Magnetic Resonance (NMR spectroscopy investigations on a novel naphthalene-substituted 1,2,3-triazole-based fluorescence sensor provided evidence for the “turn-on” detection of anions. The one-step, facile synthesis of the sensors was implemented using the “Click chemistry” approach in good yield. When investigated for selectivity and sensitivity against a series of anions (F−, Cl−, Br−, I−, H2PO4−, ClO4−, OAc−, and BF4−, the sensor displayed the strongest fluorometric response for the fluoride anion. NMR and fluorescence spectroscopic studies validate a 1:1 binding stoichiometry between the sensor and the fluoride anion. Single crystal X-ray diffraction evidence revealed the structure of the sensor in the solid state.

  1. Overview of DFIG-based Wind Power System Resonances under Weak Networks

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2017-01-01

    The wind power generation techniques are continuing to develop and increasing numbers of Doubly Fed Induction Generator (DFIG)-based wind power systems are connecting to the on-shore and off-shore grids, local standalone weak networks, and also micro grid applications. The impedances of the weak...... weak network respectively. This paper will discuss the SSR and the HFR phenomena based on the impedance modeling of the DFIG system and the weak networks, and the cause of these two resonances will be explained in details. The following factors including 1) transformer configuration; 2) different power...... networks are too large to be neglected and require careful attention. Due to the impedance interaction between the weak network and the DFIG system, both Sub- Synchronous Resonance (SSR) and High Frequency Resonance (HFR) may occur when the DFIG system is connected to the series or parallel compensated...

  2. Crosslinked anion exchange membranes with primary diamine-based crosslinkers for vanadium redox flow battery application

    Science.gov (United States)

    Cha, Min Suc; Jeong, Hwan Yeop; Shin, Hee Young; Hong, Soo Hyun; Kim, Tae-Ho; Oh, Seong-Geun; Lee, Jang Yong; Hong, Young Taik

    2017-09-01

    A series of polysulfone-based crosslinked anion exchange membranes (AEMs) with primary diamine-based crosslinkers has been prepared via simple a crosslinking process as low-cost and durable membranes for vanadium redox flow batteries (VRFBs). Chloromethylated polysulfone is used as a precursor polymer for crosslinked AEMs (CAPSU-x) with different degrees of crosslinking. Among the developed AEMs, CAPSU-2.5 shows outstanding dimensional stability and anion (Cl-, SO42-, and OH-) conductivity. Moreover, CAPSU-2.5 exhibits much lower vanadium ion permeability (2.72 × 10-8 cm2 min-1) than Nafion 115 (2.88 × 10-6 cm2 min-1), which results in an excellent coulombic efficiency of 100%. The chemical and operational stabilities of the membranes have been investigated via ex situ soaking tests in 0.1 M VO2+ solution and in situ operation tests for 100 cycles, respectively. The excellent chemical, physical, and electrochemical properties of the CAPSU-2.5 membrane make it suitable for use in VRFBs.

  3. Size Switchable Supramolecular Nanoparticle Based on Azobenzene Derivative within Anionic Pillar[5]arene

    Science.gov (United States)

    Zhang, Cai-Cai; Li, Sheng-Hua; Zhang, Cui-Fang; Liu, Yu

    2016-11-01

    A photo/thermal-switchable supramolecular nanoparticles assembly has been constructed based on an inclusion complex between anionic pillar[5]arene 2C-WP5A and azobenzene derivative Azo-py-OMe (G). The novel anionic pillar[5]arene-based host-guest inclusion complexation was investigated by the 1H NMR titration, 2D ROESY and isothermal titration microcalorimetry (ITC) showing high association constant (Ka) of (2.60 ± 0.06) × 104 M-1 with 1:1 binding stoichiometry. Furthermore, the supramolecular nanoparticles assembly can be conveniently obtained from G and a small amount of 2C-WP5A in aqueous solution, which was so-called “host induced aggregating (HIA)”. The size and morphology of the supramolecular nanoparticles assembly were characterized by TEM and DLS. As a result of the photo/thermal-isomerization of G included in the cavity of 2C-WP5A, the size of these nanoparticles could reversibly change from ~800 nm to ~250 nm, which could switch the solution of this assembly from turbid to clear.

  4. Behaviour of fibroblasts on water born acrylonitrile-based copolymers containing different cationic and anionic moieties.

    Science.gov (United States)

    Scharnagl, N; Hiebl, B; Trescher, K; Zierke, M; Behl, M; Kratz, K; Jung, F; Lendlein, A

    2012-01-01

    The chemical composition of a substrate can influence the adhesion, viability and proliferation of cells seeded on the substrate. The aim of this work was to investigate the influence of different cationic or anionic moieties in acrylonitrile-based copolymers on the interaction with fibroblasts. A series of ten different types of acrylonitrile-based copolymers with a random sequence structure was prepared using a water born synthesis process to exclude potential residues of organic solvents. As charged comonomers cationic methacrylic acid-2-aminoethylester hydrochloride (AEMA), N-3-amino-propyl-methacrylamide hydrochloride (APMA) and anionic 2-methyl-2-propene-1-sulfonic acid sodium salt (NaMAS) were utilized. By application of a specific sintering procedure the copolymer materials were processed into transparent disks for conducting cell tests in direct contact. The copolymers were analyzed with respect to their composition and surface properties. Cytotoxicity tests of the polymer extracts, as well as of the disks were performed with L929 mouse fibroblasts. All copolymers showed no cytotoxic effects. Furthermore, for higher molar ratios of AEMA an increase in cell growth could be observed, which might be a hint that higher charge densities are favorable for the proliferation of L929 cells.

  5. Adsorptive removal of anionic dyes from aqueous solutions using microgel based on nanocellulose and polyvinylamine.

    Science.gov (United States)

    Jin, Liqiang; Sun, Qiucun; Xu, Qinghua; Xu, Yongjian

    2015-12-01

    A novel nanocomposite microgel based on nanocellulose and amphoteric polyvinylamine (PVAm) was fabricated via a two-step method. Firstly, cellulose nanocrystal was oxidized by sodium periodate to yield dialdehyde nanocellulose (DANC). DANC was then used as a crosslinker to react with PVAm to obtain a pH responsive microgel with high density of free amine groups. The microgel was characterized using FTIR, XRD, AFM and elemental analysis. AFM images revealed that the nanocomposite was microspherical particles with a diameter ranging from 200 to 300nm. The microgel was found to be effective in anionic dye removal at acidic conditions. The adsorption isotherms for congo red 4BS, acid red GR and reactive light yellow K-4G fit well with the Sips model, and the maximum adsorption capacities were 869.1mgg(-1), 1469.7mgg(-1) and 1250.9mgg(-1), respectively. The adsorption for these three anionic dyes all followed pseudo second order kinetics, indicating a chemisorption nature. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

    Science.gov (United States)

    Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

    2012-01-01

    Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

  7. The Acid-Base Titration of a Very Weak Acid: Boric Acid

    Science.gov (United States)

    Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

    2012-01-01

    A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

  8. In Vivo Predictive Dissolution: Comparing the Effect of Bicarbonate and Phosphate Buffer on the Dissolution of Weak Acids and Weak Bases.

    Science.gov (United States)

    Krieg, Brian J; Taghavi, Seyed Mohammad; Amidon, Gordon L; Amidon, Gregory E

    2015-09-01

    Bicarbonate is the main buffer in the small intestine and it is well known that buffer properties such as pKa can affect the dissolution rate of ionizable drugs. However, bicarbonate buffer is complicated to work with experimentally. Finding a suitable substitute for bicarbonate buffer may provide a way to perform more physiologically relevant dissolution tests. The dissolution of weak acid and weak base drugs was conducted in bicarbonate and phosphate buffer using rotating disk dissolution methodology. Experimental results were compared with the predicted results using the film model approach of (Mooney K, Mintun M, Himmelstein K, Stella V. 1981. J Pharm Sci 70(1):22-32) based on equilibrium assumptions as well as a model accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . Assuming carbonic acid is irreversible in the dehydration direction: CO2 + H2 O ← H2 CO3 , the transport analysis can accurately predict rotating disk dissolution of weak acid and weak base drugs in bicarbonate buffer. The predictions show that matching the dissolution of weak acid and weak base drugs in phosphate and bicarbonate buffer is possible. The phosphate buffer concentration necessary to match physiologically relevant bicarbonate buffer [e.g., 10.5 mM (HCO3 (-) ), pH = 6.5] is typically in the range of 1-25 mM and is very dependent upon drug solubility and pKa . © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  9. A general halide-to-anion switch for imidazolium-based ionic liquids and oligocationic systems using anion exchange resins (A- form).

    Science.gov (United States)

    Alcalde, Ermitas; Dinarès, Immaculada; Ibáñez, Anna; Mesquida, Neus

    2011-03-21

    Further studies on the application of an AER (A(-) form) method broadened the anion exchange scope of representative ionic liquids and bis(imidazolium) systems. Depending on the hydrophobicity nature of the targeted imidazolium species and counteranions, different organic solvents were used to swap halides for assorted anions, proceeding in excellent to quantitative yields.

  10. Selective detection of iodide and cyanide anions using gold-nanoparticle-based fluorescent probes.

    Science.gov (United States)

    Wei, Shih-Chun; Hsu, Pang-Hung; Lee, Yen-Fei; Lin, Yang-Wei; Huang, Chih-Ching

    2012-05-01

    We developed two simple, rapid, and cost-effective fluorescent nanosensors, both featuring bovine serum albumin labeled with fluorescein isothiocyanate (FITC))-capped gold nanoparticles (FITC-BSA-Au NPs), for the selective sensing of cyanide (CN(-)) and iodine (I(-)) ions in high-salinity solutions and edible salt samples. During the preparation of FITC-BSA-Au NP probes, when AuNPs were introduced to the mixture containing FITC and BSA, the unconjugated FITC and FITC-labeled BSA (FITC-BSA) adsorbed to the particles' surfaces. These probes operated on a basic principle that I(-) and CN(-) deposited on the surfaces of the Au NPs or the etching of Au NPs induced the release of FITC molecules or FITC-BSA into the solution, and thus restored the florescence of FITC. We employed FITC-BSA to protect the Au NPs from significant aggregation in high-salinity solutions. In the presence of masking agents such as S(2)O(8)(2-)/Pb(2+), FITC-BSA-Au NPs facilitated the selective detection of CN(-) (by at least 150-fold in comparison with other anions). We also demonstrated that the FITC-BSA-Au NPs in the presence of H(2)O(2) could selectively detect I(-) down to 50 nM. Taking advantages of their high stability and selectivity, we employed our FITC-BSA-Au NP-based probes for the detection of CN(-) and I(-) in water samples (pond water, tap water, and seawater) and detection of I(-) in edible salt samples, respectively. This simple, rapid, and cost-effective sensing system appears to demonstrate immense practical potential for the detection of anions in real samples.

  11. Experimental Demonstration of Higher Precision Weak-Value-Based Metrology Using Power Recycling

    Science.gov (United States)

    Wang, Yi-Tao; Tang, Jian-Shun; Hu, Gang; Wang, Jian; Yu, Shang; Zhou, Zong-Quan; Cheng, Ze-Di; Xu, Jin-Shi; Fang, Sen-Zhi; Wu, Qing-Lin; Li, Chuan-Feng; Guo, Guang-Can

    2016-12-01

    The weak-value-based metrology is very promising and has attracted a lot of attention in recent years because of its remarkable ability in signal amplification. However, it is suggested that the upper limit of the precision of this metrology cannot exceed that of classical metrology because of the low sample size caused by the probe loss during postselection. Nevertheless, a recent proposal shows that this probe loss can be reduced by the power-recycling technique, and thus enhance the precision of weak-value-based metrology. Here we experimentally realize the power-recycled interferometric weak-value-based beam-deflection measurement and obtain the amplitude of the detected signal and white noise by discrete Fourier transform. Our results show that the detected signal can be strengthened by power recycling, and the power-recycled weak-value-based signal-to-noise ratio can surpass the upper limit of the classical scheme, corresponding to the shot-noise limit. This work sheds light on higher precision metrology and explores the real advantage of the weak-value-based metrology over classical metrology.

  12. Predicting competitive adsorption behavior of major toxic anionic elements onto activated alumina: a speciation-based approach.

    Science.gov (United States)

    Su, Tingzhi; Guan, Xiaohong; Tang, Yulin; Gu, Guowei; Wang, Jianmin

    2010-04-15

    Toxic anionic elements such as arsenic, selenium, and vanadium often co-exist in groundwater. These elements may impact each other when adsorption methods are used to remove them. In this study, we investigated the competitive adsorption behavior of As(V), Se(IV), and V(V) onto activated alumina under different pH and surface loading conditions. Results indicated that these anionic elements interfered with each other during adsorption. A speciation-based model was developed to quantify the competitive adsorption behavior of these elements. This model could predict the adsorption data well over the pH range of 1.5-12 for various surface loading conditions, using the same set of adsorption constants obtained from single-sorbate systems. This model has great implications in accurately predicting the field capacity of activated alumina under various local water quality conditions when multiple competitive anionic elements are present. 2009 Elsevier B.V. All rights reserved.

  13. Theoretical study on cation-anion interaction and vibrational spectra of 1-allyl-3-methylimidazolium-based ionic liquids.

    Science.gov (United States)

    Xuan, Xiaopeng; Guo, Meng; Pei, Yuanchao; Zheng, Yong

    2011-05-01

    In order to deepen the understanding of the cation-anion interaction in ionic liquids, the structures of cation, anions, and cation-anion ion-pairs of 1-allyl-3-methylimidazolium-based ionic liquids are optimized using density functional theory (DFT), and their most stable geometries are discussed. The structural parameters, hydrogen bonds and interaction energies of 1-allyl-3-methylimidazolium dicyanamide ([Amim]DCA), 1-allyl-3-methylimidazolium chloride ([Amim]Cl), 1-allyl-3-methylimidazolium formate ([Amim]FmO) and 1-allyl-3-methylimidazolium acetate ([Amim]AcO) ion pairs are studied. The vibrational frequencies of [Amim]DCA and [Amim]Cl have been calculated and scaled values have been compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. anion dependence

    Indian Academy of Sciences (India)

    SUMAN Das

    the lifetime distributions show a pronounced anion dependence and suggest cluster stability time up to a few nanoseconds. Keywords. Amide deep eutectics; simulations; cluster size and lifetime distributions; anion dependence. 1. Introduction ... industrial applications.11–15 In chemical industry, they are used as ...

  15. Self-Similarity Based Corresponding-Point Extraction from Weakly Textured Stereo Pairs

    Directory of Open Access Journals (Sweden)

    Min Mao

    2014-01-01

    Full Text Available For the areas of low textured in image pairs, there is nearly no point that can be detected by traditional methods. The information in these areas will not be extracted by classical interest-point detectors. In this paper, a novel weakly textured point detection method is presented. The points with weakly textured characteristic are detected by the symmetry concept. The proposed approach considers the gray variability of the weakly textured local regions. The detection mechanism can be separated into three steps: region-similarity computation, candidate point searching, and refinement of weakly textured point set. The mechanism of radius scale selection and texture strength conception are used in the second step and the third step, respectively. The matching algorithm based on sparse representation (SRM is used for matching the detected points in different images. The results obtained on image sets with different objects show high robustness of the method to background and intraclass variations as well as to different photometric and geometric transformations; the points detected by this method are also the complement of points detected by classical detectors from the literature. And we also verify the efficacy of SRM by comparing with classical algorithms under the occlusion and corruption situations for matching the weakly textured points. Experiments demonstrate the effectiveness of the proposed weakly textured point detection algorithm.

  16. Two polyoxometallate-based supramolecular compounds influenced by the ratio between the polyoxometallate anion and organic cation.

    Science.gov (United States)

    Zhang, Qian; Liu, Jie; Lu, Jing; Gong, Shu-Wen

    2013-06-01

    Two polyoxometallate-based compounds, tris[1,1'-(butane-1,4-diyl)bis(1H-imidazol-3-ium)] bis[tetracosa-μ2-oxido-dodecaoxido-μ12-phosphato-dodecamolybdenum(VI)], (C10H16N4)3[PMo12O40]2, (I), and 1,1'-(butane-1,4-diyl)bis(1H-imidazol-3-ium) 1-[4-(1H-imidazol-1-yl)butyl]-1H-imidazol-3-ium tetracosa-μ2-oxido-dodecaoxido-μ12-phosphato-dodecamolybdenum(VI) dihydrate, (C10H16N4)(C10H15N4)[PMo12O40]·2H2O, (II), were synthesized by hydrothermal techniques at different pH values. The stoichiometric ratio between the polyoxometallate (POM) anions and organic cations is 2:3 in (I), with one of the cations lying on an inversion centre. The doubly protonated 1,1'-(butane-1,4-diyl)diimidazole (BIM) cations are linked to the [PMo12O40](3-) anions by hydrogen bonds to form a three-dimensional supramolecular network. The stoichiometric ratio of POM anions and organic cations is 1:2 in (II), and the anion is located about a centre of inversion. The partly protonated BIM cations and solvent water molecules form hydrogen bonds with the [PMo12O40](3-) anions, yielding a two-dimensional supramolecular layer. The different lattice architectures of (I) and (II) may be governed by the ratio between the POM anions and organic cations, which, in turn, is determined by the pH value.

  17. Evaluation of chitosan–anionic polymers based tablets for extended-release of highly water-soluble drugs

    Directory of Open Access Journals (Sweden)

    Yang Shao

    2015-02-01

    Full Text Available The objective of this study is to develop chitosan–anionic polymers based extended-release tablets and test the feasibility of using this system for the sustained release of highly water-soluble drugs with high drug loading. Here, the combination of sodium valproate (VPS and valproic acid (VPA were chosen as the model drugs. Anionic polymers studied include xanthan gum (XG, carrageenan (CG, sodium carboxymethyl cellulose (CMC-Na and sodium alginate (SA. The tablets were prepared by wet granulation method. In vitro drug release was carried out under simulated gastrointestinal condition. Drug release mechanism was studied. Compared with single polymers, chitosan–anionic polymers based system caused a further slowdown of drug release rate. Among them, CS–xanthan gum matrix system exhibited the best extended-release behavior and could extend drug release for up to 24 h. Differential scanning calorimetry (DSC and Fourier transform infrared spectroscopy (FTIR studies demonstrated that polyelectrolyte complexes (PECs were formed on the tablet surface, which played an important role on retarding erosion and swelling of the matrix in the later stage. In conclusion, this study demonstrated that it is possible to develop highly water-soluble drugs loaded extended-release tablets using chitosan–anionic polymers based system.

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

    Science.gov (United States)

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

    2017-05-17

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

  19. Using Standards-Based Grading to Address Students' Strengths and Weaknesses

    Science.gov (United States)

    Knaack, Susan; Kreuz, Allie; Zawlocki, Erin

    2012-01-01

    This action research project report uses standard-based grading to address the problem of traditional grades not adequately assessing student content mastery and students' lack of awareness regarding their strengths and weaknesses. Research was conducted by one elementary and two middle school teachers with 158 students between the dates of…

  20. Directional Solidification Microstructure of a Ni-Based Superalloy: Influence of a Weak Transverse Magnetic Field

    OpenAIRE

    Li, Xu; Wang, Jun; Zhang, Jiao; Han, Yanfeng; Li, Xi

    2015-01-01

    A Ni-based superalloy CMSX-6 was directionally solidified at various drawing speeds (5–20 μm·s−1) and diameters (4 mm, 12 mm) under a 0.5 T weak transverse magnetic field. The results show that the application of a weak transverse magnetic field significantly modified the solidification microstructure. It was found that if the drawing speed was lower than 10 μm·s−1, the magnetic field caused extensive macro-segregation in the mushy zone, and a change in the mushy zone length. The magnetic fie...

  1. Intrinsic dynamics of weakly and strongly confined excitons in nonpolar nitride-based heterostructures

    OpenAIRE

    Corfdir, Pierre; Levrat, Jacques; Dussaigne, Amélie; Lefebvre, Pierre; Teisseyre, Henryk; Grzegory, Izabella; Suski, Tadeusz; Ganière, Jean-Daniel; Grandjean, Nicolas; Deveaud-Plédran, Benoît

    2011-01-01

    Both weakly and strongly confined excitons are studied by time-resolved photoluminescence in a nonpolar nitride-based heterostructure grown by molecular beam epitaxy on the a-facet of a bulk GaN crystal, with an ultralow dislocation density of 2 × 105 cm-2. Strong confinement is obtained in a 4 nm thick Al0.06Ga0.94N/GaN quantum well (QW), whereas weakly confined exciton-polaritons are observed in a 200 nm thick GaN epilayer. Thanks to the low dislocation density, the effective lifetime of st...

  2. Highly photoluminescent polysilsesquioxane hybrids based on weakly fluorescent 1,8-naphthalic anhydride derivatives

    Science.gov (United States)

    Pan, Fei; Huang, Miao; Song, Jianhui; Wu, Meng; Xu, Min

    2016-07-01

    A series of highly fluorescent polysilsesquioxane materials based on 1,8-naphthalic anhydride derivatives(XNA) have been prepared. The XNAs were chemically bonded with the polysiloxane. Though the fluorescent intensities of the solution of XNAs with different substitutes make a great difference, some of them are even very weakly emissive, the fluorescent intensities of the corresponding solid polysilsesquioxane materials are strong. In this case, the electronic effect of the substitute became non-important. With restricted molecular motion and J-aggregation, some traditionally weakly fluorescent or non-fluorescent chromophoric organics due to the substituent effect may be used to prepare highly fluorescent materials.

  3. Quaternized dimethylaminoethyl methacrylate strong base anion exchange fibers for As(V) adsorption

    Science.gov (United States)

    Kavaklı, Cengiz; Akkaş Kavaklı, Pınar; Turan, Burcu Dila; Hamurcu, Aslı; Güven, Olgun

    2014-09-01

    N,N-Dimethylaminoethyl methacrylate (DMAEMA) grafted polyethylene/polypropylene (PE/PP) nonwoven fibers (DMAEMA-g-PE/PP) was prepared by radiation-induced graft polymerization. DMAEMA graft chains on nonwoven fibers were quaternized with dimethyl sulfate solution for the preparation of strong base anion exchange fibers (QDMAEMA-g-PE/PP). Fiber structures were characterized by FTIR, XPS and SEM techniques. The effect of solution pH, contact time, initial As(V) ion concentration and coexisting ions on the As(V) adsorption capacity of the QDMAEMA-g-PE/PP fibers were investigated by performing batch adsorption experiments. The adsorption of As(V) by QDMAEMA-g-PE/PP fibers was found to be independent on solution pH in the range 4.00-10.00. Kinetic experiments show that the As(V) adsorption rate was rapid and As(V) adsorption follows pseudo second-order kinetic model. As(V) adsorption equilibrium data were analyzed using Langmuir and Freundlich adsorption isotherm model equations. Langmuir and Freundlich adsorption isotherm models fitted the experimental data well. The maximum adsorption capacity (qmax) calculated from Langmuir isotherm was found to be 83.33 mg As(V)/g polymer at pH 7.00. The adsorbent was used for three cycles without significant loss of adsorption capacity. The adsorbed As(V) ions were desorbed effectively by a 0.1 M NaOH solution.

  4. Cassini CAPS-ELS observations of carbon-based anions and aerosol growth in Titan's ionosphere

    Science.gov (United States)

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

    2016-06-01

    Cassini observations of Titans ionosphere revealed an atmosphere rich in positively charged ions with masses up to > 350 amu and negatively charged ions and aerosols with mass over charge ratios as high as 13,800 amu/q. The detection of negatively charged molecules by the Cassini CAPS Electron Spectrometer (CAPS-ELS) was particularly surprising and showed how the synthesis of large aerosol-size particles takes place at altitudes much greater than previously thought. Here, we present further analysis into this CAPS-ELS dataset, through an enhanced understanding of the instrument's response function. In previous studies the intrinsic E/E energy resolution of the instrument did not allow specific species to be identified and the detections were classified into broad mass ranges. In this study we use an updated fitting procedure to show how the ELS mass spectrum can be resolved into specific peaks at multiples of carbon-based anions up to > 100 amu/q. The negatively charged ions and aerosols in Titans ionosphere increase in mass with decreasing altitude, the lightest species being observed close to Titan's exobase of ˜1,450km and heaviest species observed at altitudes < 950km. We identify key stages in this apparent growth process and report on key intermediaries which appear to trigger the rapid growth of the larger aerosol-size particles.

  5. A Polarizable Atomic Multipole-Based Force Field for Molecular Dynamics Simulations of Anionic Lipids.

    Science.gov (United States)

    Chu, Huiying; Peng, Xiangda; Li, Yan; Zhang, Yuebin; Li, Guohui

    2017-12-31

    In all of the classical force fields, electrostatic interaction is simply treated and explicit electronic polarizability is neglected. The condensed-phase polarization, relative to the gas-phase charge distributions, is commonly accounted for in an average way by increasing the atomic charges, which remain fixed throughout simulations. Based on the lipid polarizable force field DMPC and following the same framework as Atomic Multipole Optimized Energetics for BiomoleculAr (AMOEBA) simulation, the present effort expands the force field to new anionic lipid models, in which the new lipids contain DMPG and POPS. The parameters are compatible with the AMOEBA force field, which includes water, ions, proteins, etc. The charge distribution of each atom is represented by the permanent atomic monopole, dipole and quadrupole moments, which are derived from the ab initio gas phase calculations. Many-body polarization including the inter- and intramolecular polarization is modeled in a consistent manner with distributed atomic polarizabilities. Molecular dynamics simulations of the two aqueous DMPG and POPS membrane bilayer systems, consisting of 72 lipids with water molecules, were then carried out to validate the force field parameters. Membrane width, area per lipid, volume per lipid, deuterium order parameters, electron density profile, electrostatic potential difference between the center of the bilayer and water are all calculated, and compared with limited experimental data.

  6. Structure and electronic properties of ion pairs accompanying cyclic morpholinium cation and alkylphosphite anion based ionic liquids

    Science.gov (United States)

    Verma, Prakash L.; Singh, Priti; Gejji, Shridhar P.

    2017-07-01

    Molecular insights for the formation of ion pairs accompanying the cyclic ammonium cation based room temperature ionic liquids (RTILs) composed of alkyl substituted N-methylmorpholinium (RMMor) and alkylphosphite [(Rsbnd O)2PHdbnd O] (Rdbnd ethyl, butyl, hexyl, octyl) anion have been derived from the M06-2x level of theory. Electronic structures, binding energies, and spectral characteristics of the ion pairs underlying these RTILs have been characterized. The ion pair formation is largely governed by Csbnd H⋯O and other intermolecular interactions. Calculated binding energies increase with the increasing alkyl chain on either cation or alkylphosphite anion. The cation-anion binding reveals signature in the frequency down-(red) shift of the characteristic anionic Pdbnd O stretching whereas the Psbnd H stretching exhibits a shift in the opposite direction in vibrational spectra which has further been rationalized through molecular electron density topography. Correlations of measured electrochemical stability with the separation of frontier orbital energies and binding energies in the ion pairs have further been established.

  7. Effect of a weak layer at the base of an oceanic plate on subduction dynamics

    Science.gov (United States)

    Carluccio, Roberta; Kaus, Boris

    2017-04-01

    The plate tectonics model relies on the concept of a relatively rigid lithospheric lid moving over a weaker asthenosphere. In this frame, the lithosphere asthenosphere boundary (LAB) is a first-order discontinuity that accommodates differential motions between tectonic plates and the underlying mantle. Recent seismic studies have revealed the existence of a low velocity and high electrical conductivity layer at the base of subducting tectonic plates. This thin layer has been interpreted as being weak and slightly buoyant and was suggested to affect the dynamics of subducting plates. However, geodynamically, the role of a weak layer at the base of the lithosphere remains poorly studied, especially at subduction zones. Therefore, we here use numerical models to investigate the first-order effects of a weak buoyant layer at the LAB on subduction dynamics. We employ both 2-D and 3-D models in which the slab and mantle are either linear viscous or have a more realistic temperature-dependent visco-elastic-plastic rheology. Results show that a weak layer affects the dynamics of the plates, foremost by increasing the subduction speed. The impact of this effect depends on the thickness of the layer and the viscosity contrast between the mantle and the weak layer. For moderate viscosity contrasts (1000), it can also change the morphology of the subduction itself, perhaps because this changes the overall effective viscosity contrast between the slab the and the mantle. For thinner layers, the overall effect is reduced. Yet, if seismological observations are correct that suggests that this layer is 10 km thick and partially molten, such that the viscosity is 1000 times lower than that of the mantle, our models suggest that this effect should be measurable. Some of our models also show a pile-up of weak material in the bending zone of the subducting plate, consistent with recent seismological observations.

  8. Born energy, acid-base equilibrium, structure and interactions of end-grafted weak polyelectrolyte layers

    Science.gov (United States)

    Nap, R. J.; Tagliazucchi, M.; Szleifer, I.

    2014-01-01

    This work addresses the effect of the Born self-energy contribution in the modeling of the structural and thermodynamical properties of weak polyelectrolytes confined to planar and curved surfaces. The theoretical framework is based on a theory that explicitly includes the conformations, size, shape, and charge distribution of all molecular species and considers the acid-base equilibrium of the weak polyelectrolyte. Namely, the degree of charge in the polymers is not imposed but it is a local varying property that results from the minimization of the total free energy. Inclusion of the dielectric properties of the polyelectrolyte is important as the environment of a polymer layer is very different from that in the adjacent aqueous solution. The main effect of the Born energy contribution on the molecular organization of an end-grafted weak polyacid layer is uncharging the weak acid (or basic) groups and consequently decreasing the concentration of mobile ions within the layer. The magnitude of the effect increases with polymer density and, in the case of the average degree of charge, it is qualitatively equivalent to a small shift in the equilibrium constant for the acid-base equilibrium of the weak polyelectrolyte monomers. The degree of charge is established by the competition between electrostatic interactions, the polymer conformational entropy, the excluded volume interactions, the translational entropy of the counterions and the acid-base chemical equilibrium. Consideration of the Born energy introduces an additional energetic penalty to the presence of charged groups in the polyelectrolyte layer, whose effect is mitigated by down-regulating the amount of charge, i.e., by shifting the local-acid base equilibrium towards its uncharged state. Shifting of the local acid-base equilibrium and its effect on the properties of the polyelectrolyte layer, without considering the Born energy, have been theoretically predicted previously. Account of the Born energy leads

  9. Born energy, acid-base equilibrium, structure and interactions of end-grafted weak polyelectrolyte layers.

    Science.gov (United States)

    Nap, R J; Tagliazucchi, M; Szleifer, I

    2014-01-14

    This work addresses the effect of the Born self-energy contribution in the modeling of the structural and thermodynamical properties of weak polyelectrolytes confined to planar and curved surfaces. The theoretical framework is based on a theory that explicitly includes the conformations, size, shape, and charge distribution of all molecular species and considers the acid-base equilibrium of the weak polyelectrolyte. Namely, the degree of charge in the polymers is not imposed but it is a local varying property that results from the minimization of the total free energy. Inclusion of the dielectric properties of the polyelectrolyte is important as the environment of a polymer layer is very different from that in the adjacent aqueous solution. The main effect of the Born energy contribution on the molecular organization of an end-grafted weak polyacid layer is uncharging the weak acid (or basic) groups and consequently decreasing the concentration of mobile ions within the layer. The magnitude of the effect increases with polymer density and, in the case of the average degree of charge, it is qualitatively equivalent to a small shift in the equilibrium constant for the acid-base equilibrium of the weak polyelectrolyte monomers. The degree of charge is established by the competition between electrostatic interactions, the polymer conformational entropy, the excluded volume interactions, the translational entropy of the counterions and the acid-base chemical equilibrium. Consideration of the Born energy introduces an additional energetic penalty to the presence of charged groups in the polyelectrolyte layer, whose effect is mitigated by down-regulating the amount of charge, i.e., by shifting the local-acid base equilibrium towards its uncharged state. Shifting of the local acid-base equilibrium and its effect on the properties of the polyelectrolyte layer, without considering the Born energy, have been theoretically predicted previously. Account of the Born energy leads

  10. Imidazolium-based anion exchange membranes for alkaline anion fuel cells: (2) elucidation of the ionic structure and its impact on conducting properties.

    Science.gov (United States)

    Yoshimura, Kimio; Zhao, Yue; Hasegawa, Shin; Hiroki, Akihiro; Kishiyama, Yoshihiro; Shishitani, Hideyuki; Yamaguchi, Susumu; Tanaka, Hirohisa; Koizumi, Satoshi; Appavou, Marie-Sousai; Radulescu, Aurel; Richter, Dieter; Maekawa, Yasunari

    2017-11-22

    In our previous study (Soft Matter, 2016, 12, 1567), the relationship between the morphology and properties of graft-type imidazolium-based anion exchange membranes (AEMs) was revealed, in that the semi-crystalline features of the polymer matrix maintain its mechanical properties and the formation of interconnected hydrophilic domains promotes the membrane conductivity. Here, we report a novel ionic structure of the same graft-type AEMs with different grafting degrees, analyzed using a small-angle X-ray scattering method under different relative humidity (RH) conditions. The characteristic "ionomer peak" with a corresponding correlation distance of approximately 1.0 nm was observed at RH ionic clusters, but close to the Bjerrum length of water. Since the representative number of water molecules per cation, nw, was small, we proposed that dissociated ion-pairs are distributed in the hydrophilic domains (ion-channels). At RH < 80%, ion-channels are disconnected, however in liquid water, they are well-connected as evidenced by the sharp increase in nw. The disconnected ion-channels even under relatively high RH conditions should be a substantial factor for the low power generation efficiency of AEM-type fuel cells.

  11. Lithium Insertion Mechanism in Iron-Based Oxyfluorides with Anionic Vacancies Probed by PDF Analysis.

    Science.gov (United States)

    Dambournet, Damien; Chapman, Karena W; Duttine, Mathieu; Borkiewicz, Olaf; Chupas, Peter J; Groult, Henri

    2015-08-01

    The mechanism of lithium insertion that occurs in an iron oxyfluoride sample with a hexagonal-tungsten-bronze (HTB)-type structure was investigated by the pair distribution function. This study reveals that upon lithiation, the HTB framework collapses to yield disordered rutile and rock salt phases followed by a conversion reaction of the fluoride phase toward lithium fluoride and nanometer-sized metallic iron. The occurrence of anionic vacancies in the pristine framework was shown to strongly impact the electrochemical activity, that is, the reversible capacity scales with the content of anionic vacancies. Similar to FeOF-type electrodes, upon de-lithiation, a disordered rutile phase forms, showing that the anionic chemistry dictates the atomic arrangement of the re-oxidized phase. Finally, it was shown that the nanoscaling and structural rearrangement induced by the conversion reaction allow the in situ formation of new electrode materials with enhanced electrochemical properties.

  12. Anion Sensing Properties of New Colorimetric Chemosensors Based on Thiourea and Urea Moieties

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Wan; Kim, Jung Hwan; Hwang, Jae Young; Park, Jong Keun; Kim, Jae Sang [Gyeongsang National University, Jinju (Korea, Republic of)

    2012-04-15

    A new colorimetric sensors containing thiourea (1-(4-nitrophenyl)-3-quinolin-6-ylthiourea: 1) and urea(1-(4- nitrophenyl)-3-quinolin-6-ylurea: 2) moieties for fluoride were designed and synthesized. These simple receptors were characterized their stoichiometry, and investigates the mechanism of their selectivity as anion receptors. The addition of tetrabutylammonium fluoride salts to the solution of receptors caused a dramatically and clearly observable color changes from colorless to yellow. To examine their application as anion receptors by UV-vis and {sup 1}H NMR spectroscopy results revealed their higher selectivity for fluoride ion than other anions. The receptors and fluoride ion formed a 1:1 stoichiometry complex through strong hydrogen bonding interactions in the first step, followed by a process of deprotonation in presence of an excess of F{sup -} in DMSO solvent

  13. New magnetic organic inorganic composites based on hydrotalcite-like anionic clays for drug delivery

    Science.gov (United States)

    Carja, Gabriela; Chiriac, Horia; Lupu, Nicoleta

    2007-04-01

    The structural "memory effect" of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin-hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments.

  14. Physical Properties of Some ET-Based Organic Metals and Superconductors with Mercury Containing Anions

    Science.gov (United States)

    Lyubovskii, R. B.; Lyubovskaya, R. N.; Dyachenko, O. A.

    1996-12-01

    Because of mercury atoms capability of forming the compounds with various coordination, the application of the electrolytes with Hg containing anions in electrochemical oxidation of ET (bis(ethylenedithio)tetrathiafulvalene) results in the formation of ET salts with the anions of different composition. The properties of organic metals and superconductors are briefly described for three families: 1) ET4Hg{3-δ}X8 ((δ 0, and a series of other peculiarities. Shubnikov-de Haas oscillations were observed for some salts of (ET)8[ Hg4X{12}(C6H5Y)2] family. The possible types of Fermi surface are discussed for these salts.

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

    Science.gov (United States)

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

    2017-07-01

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

  16. DFT-Based Comparative Study about the Influence of Fluorine and Hydroxyl Anions on Opto-Electric Properties of Borate Crystals: Choice for Better Anion.

    Science.gov (United States)

    Bashir, Beenish; Zhang, Bingbing; Lee, Ming-Hsien; Pan, Shilie; Yang, Zhihua

    2017-05-15

    Replacing hydroxyl anions OH¯ by fluorine anions F¯ in borates can cause the blue shift of the UV cutoff edge and also exhibits apparent differences in nonlinear optical (NLO) properties. To clarify the intrinsic difference between OH¯ anions and F¯ anions, several typical borates with different types of cations (p-cations with lone-pair electrons, trivalent rare-earth, and alkaline earth metals) have been studied. The theoretical studies reveal that the blue shift in the band gap of borates with fluorine as compared to those with hydroxyl can be assumed to be the result of weaker interaction of the cation-fluoride (La/Bi/B-F) bonds compared to that of the cation-oxygen and hydroxyl bonds. NLO properties are found to have the order of BiB2O4F > BiB2O4(OH)> LaB2O4F ≈ LaB2O4(OH). The large difference can be attributed mainly to the stereochemical activity of the lone pair (SCALP) effect of the Bi cations and the special BO3F with strong anisotropy as compared to the BO4 group. The energy spanning of F-2p orbitals is more extended in BiB2O4F as compared to LaB2O4F, Sr3B6O11F2, and Ba3B6O11F2 due to the bonding of Bi/B-F, which indicates F-2p orbitals have more chance to overlap with surrounding atoms and enhance the polarizability in all systems. Moreover, the degree of SCALP of the Bi cations is apparently activated by the introduction of the F¯ anions, which causes an obvious enhancement in NLO properties in bismuth borates with F¯. These investigations will help us to classify the solid-state chemistry of F¯ and OH¯ anions in borate systems with different types of metal cations.

  17. Interaction between rhein acyl glucuronide and methotrexate based on human organic anion transporters.

    Science.gov (United States)

    Yuan, Yuan; Yang, Hua; Kong, Linghua; Li, Yuan; Li, Ping; Zhang, Hongjian; Ruan, Jianqing

    2017-11-01

    Rhein, a major bioactive compound of many medicinal herbs and the prodrug of diacerein, is often used with low dose of methotrexate as drug combination to treat rheumatoid arthritis. In this study, potential drug-drug interaction between methotrexate and rhein was investigated based on organic anion transporters (OAT). Our study demonstrated that rhein acyl glucuronide (RAG), the major metabolite of rhein in the human blood circulation, significantly inhibited the uptake of p-aminohippurate in hOAT1 transfected cells with IC50 value of 691 nM and estrone sulfate uptake in hOAT3 transfected cells with IC50 value of 78.5 nM. As the substrate of both hOAT1 and hOAT3, the methotrexate transport was significantly inhibited by RAG in hOAT1 transfected cells at 50 μM and hOAT3 transfected cells at 1 μM by 69% and 87%, respectively. Further in vivo study showed that after co-administrated with RAG in rats the AUC0-24 values of methotrexate increased from 3109 to 5370 ng/mL*hr and the t1/2 was prolonged by 40.5% (from 7.4 to 10.4 h), demonstrating the inhibitory effect of RAG on methotrexate excretion. In conclusion, rhein acyl glucuronide could significantly decrease the transport of methotrexate by both hOAT1 and hOAT3. The combination use of rhein, diacerein or other rhein-containing herbs with methotrexate may cause obvious drug-drug interaction and require close monitoring for potential drug interaction in clinical practice. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Fashion Evaluation Method for Clothing Recommendation Based on Weak Appearance Feature

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2017-01-01

    Full Text Available With the rapid rising of living standard, people gradually developed higher shopping enthusiasm and increasing demand for garment. Nowadays, an increasing number of people pursue fashion. However, facing too many types of garment, consumers need to try them on repeatedly, which is somewhat time- and energy-consuming. Besides, it is difficult for merchants to master the real-time demand of consumers. Herein, there is not enough cohesiveness between consumer information and merchants. Thus, a novel fashion evaluation method on the basis of the appearance weak feature is proposed in this paper. First of all, image database is established and three aspects of appearance weak feature are put forward to characterize the fashion level. Furthermore, the appearance weak features are extracted according to the characters’ facial feature localization method. Last but not least, consumers’ fashion level can be classified through support vector product, and the classification is verified with the hierarchical analysis method. The experimental results show that consumers’ fashion level can be accurately described based on the indexes of appearance weak feature and the approach has higher application value for the clothing recommendation system.

  19. Structure and oil responsiveness of viscoelastic fluids based on mixed anionic/cationic wormlike surfactant micelles

    Science.gov (United States)

    Shibaev, A. V.; Makarov, A. V.; Aleshina, A. L.; Rogachev, A. V.; Kuklin, A. I.; Philippova, O. E.

    2017-05-01

    In this work, a combination of small-angle neutron scattering, dynamic light scattering and rheometry was applied in order to investigate the structure and oil responsiveness of anionic/cationic wormlike surfactant micelles formed in a mixture of potassium oleate and n-octyltrimethylammonium bromide (C8TAB). A new facile method of calculating the structure factor of charged interacting wormlike micelles was proposed. It was shown that the mean distance between the micelles decreases upon the increase of the amount of cationic co-surfactant and lowering of the net micellar charge. It was demonstrated that highly viscous fluids containing mixed anionic/cationic wormlike micelles are highly responsive to oil due to its solubilization inside the micellar cores, which leads to the disruption of micelles and formation of microemulsion droplets. Experimental data suggest that solubilization of oil proceeds differently in the case of mixed anionic/cationic micelles in the absence of salt, and anionic micelles of the same surfactant in the presence of KCl.

  20. Amino acids as chiral anionic ligands for ruthenium based asymmetric olefin metathesis.

    Science.gov (United States)

    Ivry, Elisa; Ben-Asuly, Amos; Goldberg, Israel; Lemcoff, N Gabriel

    2015-03-04

    Several amino acid ligands were introduced into the Hoveyda-Grubbs 2nd generation complex by a facile anionic ligand exchange. The chiral pre-catalysts obtained displayed enantioselectivity in asymmetric ring-closing and ring-opening cross-metathesis reactions. Reduction of the lability of the carboxylate ligands was found to be cardinal for improving the observed enantiomeric product enrichment.

  1. Anion and cation dynamics of sulfonylamide-based ionic liquids and the solid-liquid transitions.

    Science.gov (United States)

    Imanari, Mamoru; Fujii, Kozo; Mukai, Tomohiro; Mizushima, Noriko; Seki, Hiroko; Nishikawa, Keiko

    2015-04-14

    Some of the important factors that characterise room-temperature ionic liquids (RTILs) are the variety of conformations adopted by the constituent ions and their flexibility. Using 1,3-dimethylimidazolium bis(fluorosulfonyl)amide ([C1mim][FSA]) and 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)amide ([C1mim][NTf2]) as samples, the longitudinal and transverse relaxation times (T1 and T2) for (19)F and (1)H were determined as a function of temperature and were correlated with the dynamics of the phase behaviours of the two RTILs. Because the anions and cations in the two compounds have (19)F and (1)H nuclei, respectively, their dynamics can be independently investigated and the relationships between them can be discussed. For [C1mim][FSA], the only observed phase changes included melting and crystallisation. The temperature dependences of T1 and T2 for (19)F were similar to those of T1 and T2 for (1)H, indicating similar dynamics due to the formation of strong anion-cation interactions. For [C1mim][NTf2], the T1 and T2 values for both (19)F and (1)H discontinuously changed at same temperatures, which were assigned to the crystallisation and melting points. However, the T1 curves for (19)F and (1)H were different in the crystalline region, suggesting independent dynamics for the anions and cations in [C1mim][NTf2]. In the crystalline state for each salt, the cation dynamics was distinctly separated into the framework movement of the imidazolium ring and the movement of the methyl groups, while the anion dynamics was characterised by the movement of the entire anion. The influence of the crystal structure on the dynamics of each salt was also considered.

  2. A Quantum Proxy Weak Blind Signature Scheme Based on Controlled Quantum Teleportation

    Science.gov (United States)

    Cao, Hai-Jing; Yu, Yao-Feng; Song, Qin; Gao, Lan-Xiang

    2015-04-01

    Proxy blind signature is applied to the electronic paying system, electronic voting system, mobile agent system, security of internet, etc. A quantum proxy weak blind signature scheme is proposed in this paper. It is based on controlled quantum teleportation. Five-qubit entangled state functions as quantum channel. The scheme uses the physical characteristics of quantum mechanics to implement message blinding, so it could guarantee not only the unconditional security of the scheme but also the anonymity of the messages owner.

  3. New Y-function based MOSFET parameter extraction method from weak to strong inversion range

    Science.gov (United States)

    Henry, J. B.; Rafhay, Q.; Cros, A.; Ghibaudo, G.

    2016-09-01

    A new Y-function based MOSFET parameter extraction method is proposed. This method relies on explicit expressions of inversion charge and drain current versus Yc(=Qi√Cgc)-function and Y(=Id/√gm)-function, respectively, applicable from weak to strong inversion range. It enables a robust MOSFET parameter extraction even for low gate voltage overdrive, whereas conventional extraction techniques relying on strong inversion approximation fail.

  4. Multi Dark Lens Simulations: weak lensing light-cones and data base presentation

    Science.gov (United States)

    Giocoli, Carlo; Jullo, Eric; Metcalf, R. Benton; de la Torre, Sylvain; Yepes, Gustavo; Prada, Francisco; Comparat, Johan; Göttlober, Stefan; Kyplin, Anatoly; Kneib, Jean-Paul; Petkova, Margarita; Shan, Huan Yuan; Tessore, Nicolas

    2016-09-01

    In this paper we present a large data base of weak lensing light cones constructed using different snapshots from the Big MultiDark simulation (BigMDPL). The ray-tracing through different multiple plane has been performed with the GLAMER code accounting both for single source redshifts and for sources distributed along the cosmic time. This first paper presents weak lensing forecasts and results according to the geometry of the VIPERS-W1 and VIPERS-W4 field of view. Additional fields will be available on our data base and new ones can be run upon request. Our data base also contains some tools for lensing analysis. In this paper we present results for convergence power spectra, one point and high order weak lensing statistics useful for forecasts and for cosmological studies. Covariance matrices have also been computed for the different realizations of the W1 and W4 fields. In addition we compute also galaxy-shear and projected density contrasts for different halo masses at two lens redshift according to the CFHTLS source redshift distribution both using stacking and cross-correlation techniques, finding very good agreement.

  5. A BTT-Based Colorimetric Dual Sensor for Hg(II and Selected Anions with Molecular Logic Operations

    Directory of Open Access Journals (Sweden)

    Veikko Uahengo

    2016-01-01

    Full Text Available A benzotrithiophenes (BTT based colorimetric sensor (2 was synthesized via a simple one-step reaction process, and its recognition properties towards several biologically important anions and cations were investigated by naked eye observation and spectroscopic methods of UV-vis and 1H NMR analysis in DMSO. The molar addition of anions such as F−, AcO−, and H2PO4- induced a marked red shift of the charge transfer band (Δλ=94 nm, from 440 nm to 534 nm concomitant with a clearly visible “naked eye” detectable colorimetric activities (from orange to pink. However, the molar addition of H2PO4- did not induce significant spectral changes, compared to F− and AcO−. Furthermore, the molar addition of Hg2+ to 2 resulted in hypochromic shift at 440 nm and the eventual disappearance of a low energy band at 534 nm, concomitant with the colorimetric activities (from orange to yellow. Moreover, both spectral and color changes induced by the addition of anions (F− and AcO− were all reversible by the molar addition of metal cations of 3d5–10. The reversibility properties triggered the logic operation studies, and, subsequently, the complementary IMP/INH logic functions based on color and spectral switching (ON/OFF were confirmed. Conclusively, 2 can thus be utilized as a colorimetric molecular switch modulated by AcO−/MII.

  6. A Quantum Multi-Proxy Weak Blind Signature Scheme Based on Entanglement Swapping

    Science.gov (United States)

    Yan, LiLi; Chang, Yan; Zhang, ShiBin; Han, GuiHua; Sheng, ZhiWei

    2017-02-01

    In this paper, we present a multi-proxy weak blind signature scheme based on quantum entanglement swapping of Bell states. In the scheme, proxy signers can finish the signature instead of original singer with his/her authority. It can be applied to the electronic voting system, electronic paying system, etc. The scheme uses the physical characteristics of quantum mechanics to implement delegation, signature and verification. It could guarantee not only the unconditionally security but also the anonymity of the message owner. The security analysis shows the scheme satisfies the security features of multi-proxy weak signature, singers cannot disavowal his/her signature while the signature cannot be forged by others, and the message owner can be traced.

  7. Precision improvement of surface plasmon resonance sensors based on weak-value amplification.

    Science.gov (United States)

    Luo, Lan; Qiu, Xiaodong; Xie, Linguo; Liu, Xiong; Li, Zhaoxue; Zhang, Zhiyou; Du, Jinglei

    2017-09-04

    In this paper, a method to improve the precision of prism-coupler-based surface plasmon resonance (SPR) sensors using weak-value amplification (WVA) is presented. A general theory model to describe the post-selected SPR sensing system is established and the polarization-dependent amplitude and phase evolutions induced by the SPR are regarded as the weak interactions in the WVA formalism. As a consequence of WVA, the detected signal can be enhanced with respect to the technical noise which is dependent on the post-selected light intensity. The precision of our method reaches 2.9 × 10-7RIU, which is improved nearly one order of magnitude compared to the conventional sensing technique.

  8. Impedance-Based High Frequency Resonance Analysis of DFIG System in Weak Grids

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The impedance-based model of Doubly Fed Induction Generator (DFIG) systems, including the rotor part (Rotor Side Converter (RSC) and induction machine), and the grid part (Grid Side Converter (GSC) and its output filter), has been developed for analysis and mitigation of the Sub- Synchronous...... Resonance (SSR). However, the High Frequency Resonance (HFR) of DFIG systems due to the impedance interaction between DFIG system and parallel compensated weak network is often overlooked. This paper thus investigates the impedance characteristics of DFIG systems for the analysis of HFR. The influences...... of the rotor speed variation, the machine mutual inductance and the digital control delay are evaluated. Two resonances phenomena are revealed, i.e., 1) the series HFR between the DFIG system and weak power grid; 2) the parallel HFR between the rotor part and the grid part of DFIG system. The impedance...

  9. Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

    Energy Technology Data Exchange (ETDEWEB)

    Nicoleti, Celso R.; Marini, Vanderleia G.; Zimmermann, Lizandra M.; Machado, Vanderlei G., E-mail: vanderlei.machado@ufsc.br [Departamento de Quimica, Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-08-15

    4-(4-Nitrobenzylideneamine)phenol was used in two strategies allowing the highly selective detection of F{sup -} and CN{sup -}. Firstly, the compound in acetonitrile acts as a chromogenic chemosensor based on the idea that more basic anions cause its deprotonation (colorless solution), generating a colored solution containing phenolate. The discrimination of CN{sup -} over F{sup -} was obtained by adding 1.4% water to acetonitrile: water preferentially solvates F{sup -}, leaving the CN{sup -} free to deprotonate the compound. Another strategy involved an assay comprised of the competition between phenolate dye and the analyte for calyx[4]pyrrole in acetonitrile, a receptor highly selective for F{sup -}. Phenolate and calyx[4]pyrrole form a hydrogen-bonded complex, which changes the color of the medium. On the addition of various anions, only F{sup -} was able to restore the original color corresponding to phenolate in solution due to the fact that the anion dislodges phenolate from the complexation site. (author)

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

    Science.gov (United States)

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

    2013-11-01

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

  11. New magnetic organic-inorganic composites based on hydrotalcite-like anionic clays for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Carja, Gabriela [Department of Physical Chemistry, Faculty of Industrial Chemistry, Technical University of Iasi, 71 Mangeron Boulevard, 700050 Iasi (Romania); Chiriac, Horia [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi (Romania)]. E-mail: hchiriac@phys-iasi.ro; Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi (Romania)

    2007-04-15

    The structural 'memory effect' of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin-hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments.

  12. The growth of ionic crystals based on the halogenation of copper cluster anions.

    Science.gov (United States)

    Luo, Zhixun; Smith, Jordan C; Woodward, W Hunter; Castleman, A W

    2012-03-08

    We investigated the halogenation reactivity of copper cluster anions produced via a magnetron-sputter source after introduction into a fast-flow tube reaction apparatus simultaneously with chlorine gas. Interesting cluster products corresponding to [Cu(n)Cl(n+1)](-) (n = 1-6) were observed with notable stability, and the mass distribution of these clusters exhibits an exponential decay with increasing values of n. Reaction kinetics analysis is provided on the gas-phase reactivity of copper cluster anions with chlorine. First-principle calculations suggest a series of cubic-like structures for these species similar to the structure of alkali halide clusters due to their similar electronic configurations. These structures act as a starting point in the formation of ionic crystals.

  13. Series of SHG Materials Based on Lanthanide Borate-Acetate Mixed Anion Compounds.

    Science.gov (United States)

    Yang, Hui; Hu, Chun-Li; Xu, Xiang; Mao, Jiang-Gao

    2015-08-03

    The first examples of lanthanide borate-acetate mixed anion compounds, namely, Ln2(CH3CO2)2[B5O9(OH)]·H2O (Ln = La 1; Ce 2; Pr 3), were synthesized under hydrothermal conditions. These compounds are isostructural and crystallize in polar space group Cc. They display a unique three-dimensional (3D) framework built by a 3D network of lanthanide borate further decorated by acetate anions. The borate anion exhibits a 2D layer in the ac plane with large 9-member rings (MRs) which are filled by lanthanide(III) ions into a {Ln[B5O9(OH)]}(-) 2D layer. Adjacent {Ln[B5O9(OH)]}(-) layers are bridged by remaining lanthanide (III) ions to form a 3D network of lanthanide borate. It is noteworthy that Ln2(CH3CO2)2[B5O9(OH)]·H2O (Ln = La 1; Ce 2; Pr 3) can be changed into Ln2(CH3CO2)2[B5O9(OH)] (Ln = La 4; Ce 5; Pr 6) under heating at 500 K. Compounds 1-4 display moderate SHG signals of about 2.0, 1.0, 1.4, and 2.5 times that of KH2PO4, respectively, and they are phase matchable. Their SHG responses mainly arise from the synergistic polarization effects of both asymmetric borate clusters and π-conjugated CH3COO(-) anions.

  14. Cross-linked comb-shaped anion exchange membranes with high base stability

    Energy Technology Data Exchange (ETDEWEB)

    Li, NW; Wang, LZ; Hickner, M

    2014-01-01

    A unique one-step cross-linking strategy that connects quaternary ammonium centers using Grubbs II-catalyzed olefin metathesis was developed. The cross-linked anion exchange membranes showed swelling ratios of less than 10% and hydroxide conductivities of 18 to 40 mS cm(- 1). Cross-linking improved the membranes' stability to hydroxide degradation compared to their non-cross-linked analogues.

  15. A green approach for preparing anion exchange membrane based on cardo polyetherketone powders

    Science.gov (United States)

    Hu, Jue; Zhang, Chengxu; Zhang, Xiaodong; Chen, Longwei; Jiang, Lin; Meng, Yuedong; Wang, Xiangke

    2014-12-01

    Anion exchange membranes (AEMs) have attracted great attention due to their irreplaceable role in platinum-free fuel cell applications. The majority of AEM preparations have been performed in two steps: the grafting of functional groups and quaternization. Here, we adopted a simpler, more eco-friendly approach for the first time to prepare AEMs by atmospheric-pressure plasma-grafting. This approach enables the direct introduction of anion exchange groups (benzyltrimethylammonium groups) into the polymer matrix, overcoming the need for toxic chloromethyl ether and quaternization reagents. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and 1H NMR spectroscopy results demonstrate that benzyltrimethylammonium groups have been successfully grafted into the cardo polyetherketone (PEK-C) matrix. Thermogravimetric analysis reveals that the plasma-grafting technique is a facile and non-destructive method able to improve the thermal stability of the polymer matrix due to the strong preservation of the PEK-C backbone structure and the cross-linking of the grafted side chains. The plasma-grafted PG-NOH membrane, which shows satisfactory alcohol resistance (ethanol permeability of 6.3 × 10-7 cm2 s-1), selectivity (1.2 × 104 S s cm-3), thermal stability (safely used below 130 °C), chemical stability, anion conductivity (7.7 mS cm-1 at 20 °C in deionized water) and mechanical properties is promising for the construction of high-performance fuel cells.

  16. Effect of non-phospholipid-based cationic and phospholipid-based anionic nanosized emulsions on skin retention and anti-inflammatory activity of celecoxib.

    Science.gov (United States)

    Tamilvanan, S; Baskar, Raj

    2013-01-01

    Celecoxib (CXB, 0.2 g)-loaded anionic and cationic nanosized emulsions were prepared by a well-established combined emulsification method. To investigate the effect of non-phospholipid-based cationic and phospholipid-based anionic emulsions on skin retention and anti-inflammatory activity of CXB. Using Keshary-Chien diffusion cells with cellulose acetate membrane or excised rat skin, in vitro release and skin retention of CXB from solution and emulsions were studied. The anti-inflammatory activity was evaluated by the carrageenan-induced hind paw edema method in Wistar rats. The amount of drug released through artificial membrane has decreased from 122.00 ± 0.70 μg/cm(2) for the CXB solution to 55.80 ± 0.70 μg/cm(2) for anionic emulsion, and then further decreased to 24.79 ± 0.90 μg/cm(2) for cationic emulsion. The JSS value obtained with solution, anionic, and cationic emulsions were 6825.79 ± 920.86, 2513.15 ± 382.71, and 1925.67 ± 147.42, respectively. Cationic emulsion showed a significantly higher level (P ≤ 0.05) of drug accumulation in full-thickness rat skin than anionic emulsion, and a substantially lesser percentage inhibition of edema values compared with both solution and anionic emulsion. Sustained drug release together with increased skin accumulation and simultaneously decreased skin permeation as observed with cationic emulsion should substantiate its suitability as a topical delivery vehicle for CXB.

  17. A hydrophobic gel phantom for study of thermochemical ablation: initial results using a weak acid and weak base.

    Science.gov (United States)

    Misselt, Andrew J; Edelman, Theresa L; Choi, Jeung H; Bischof, John C; Cressman, Erik N K

    2009-10-01

    To develop a model for study of exothermic chemical reactions potentially useful for tissue ablation. Seven gelatins ranging from 0.5% to 30% wt/vol with and without 15% or 30% caps and several commercial gels were evaluated. Baseline temperature measurements were taken. Acetic acid and ammonium hydroxide were sequentially injected over periods of 10-15 seconds in 1-mL aliquots, forming a discrete aqueous reaction chamber. Congo red pH indicator was included to assess the reaction. A thermocouple allowed data collection at completion of injection and every 15 seconds for 5 minutes. Injections were performed in triplicate, and average temperatures for each time point were reported. Gelatins fractured or refluxed even at the lowest concentrations tested. Most commercial gels proved too viscous and likewise led to reflux along the needle tract. A mineral oil-based gel was selected because of its ability to form a chamber without reflux or fracture and its clear colorless character, hydrophobic nature, chemical stability, viscosity, specific gravity, and cost. Temperatures during the first 60 seconds of the neutralization reaction showed an immediate increase that correlated well with concentration. The oil gel phantom is a safe, useful, readily available, inexpensive model to study mixing behaviors and maximum heating potentials for reactions that may prove useful in thermochemical tissue ablation for oncologic interventions. Measurable temperature changes occurred even at the lowest concentrations, and higher concentrations produced a greater release of heat energy.

  18. Directional Solidification Microstructure of a Ni-Based Superalloy: Influence of a Weak Transverse Magnetic Field

    Directory of Open Access Journals (Sweden)

    Xu Li

    2015-06-01

    Full Text Available A Ni-based superalloy CMSX-6 was directionally solidified at various drawing speeds (5–20 μm·s−1 and diameters (4 mm, 12 mm under a 0.5 T weak transverse magnetic field. The results show that the application of a weak transverse magnetic field significantly modified the solidification microstructure. It was found that if the drawing speed was lower than 10 μm·s−1, the magnetic field caused extensive macro-segregation in the mushy zone, and a change in the mushy zone length. The magnetic field significantly decreases the size of γ’ and the content of γ-γ’ eutectic. The formation of macro-segregation under a weak magnetic field was attributed to the interdendritic solute transport driven by the thermoelectric magnetic convection (TEMC. The γ’ phase refinement could be attributed to a decrease in nucleation activation energy owing to the magnetic field during solid phase transformation. The change of element segregation is responsible for the content decrease of γ-γ’ eutectic.

  19. Anion-π catalysis.

    Science.gov (United States)

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

    2014-02-05

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

  20. General analytical procedure for determination of acidity parameters of weak acids and bases.

    Science.gov (United States)

    Pilarski, Bogusław; Kaliszan, Roman; Wyrzykowski, Dariusz; Młodzianowski, Janusz; Balińska, Agata

    2015-01-01

    The paper presents a new convenient, inexpensive, and reagent-saving general methodology for the determination of pK a values for components of the mixture of diverse chemical classes weak organic acids and bases in water solution, without the need to separate individual analytes. The data obtained from simple pH-metric microtitrations are numerically processed into reliable pK a values for each component of the mixture. Excellent agreement has been obtained between the determined pK a values and the reference literature data for compounds studied.

  1. Enhanced LVRT Control Strategy for DFIG-Based WECS in Weak Grid

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Chen, Zhe; Iov, Florin

    2013-01-01

    An enhanced coordinated low voltage ride-through, LVRT, control strategy for a Doubly-fed Induction generator (DFIG)-based wind energy conversion system, WECS, connected to a weak grid is presented in this paper. The compliance with the grid code commitments is also considered. A proposed decoupled...... protection scheme. Furthermore, additional compensation terms are incorporated with the traditional GSC and rotor side converter, RSC, controllers to effectively suppress rotor as well as stator currents and meanwhile regulate the rotor speed. A diverse set of voltage excursions are conducted to evaluate...

  2. Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei, E-mail: kwgao@yahoo.com

    2017-05-15

    Highlights: • Zn-Al LDHs film loaded nitrate anions has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method. • The Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs film were obtained based on anion-exchange mechanism. • The Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs film could effectively protect magnesium alloy. - Abstract: Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO{sub 3} LDHs, Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

  3. Anion-exchange resin-based desulfurization process. Quarterly technical progress report, October 1, 1991--December 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Sheth, A.C.; Strevel, S.D.

    1991-12-31

    The University of Tennessee Space Institute (UTSI) has a Department of Energy grant to further develop the Institute`s anion-exchange resin-based flue gas, desulfurization concept. The developmental program proposed includes screening of commercially available resins to select three candidate resins for further study. These three resins will undergo a series of experiments designed to test the resins` performance under different process conditions (including the use of spent MHD seed material). The best of these resins will be used in optimizing the regeneration step and in testing the effects of performance enhancers. The process schematic developed from the results will be used to estimate the related economics.

  4. Palm oil anionic surfactants based emulsion breaker (Case study of emulsions breaker at Semanggi Field production wells)

    Science.gov (United States)

    Muhpidah; Hambali, E.; Suryani, A.; Kartika, I. A.

    2017-05-01

    The presence of emulsion in oil production process is undesirable. The emulsion will increase the production costs, transportation and costs related to emulsion separation process between water and oil. The development of palm oil-based surfactant as an emulsion breaker needs to be conducted given the availability of abundant raw materials in Indonesia and as an alternative to petroleum-based surfactant. The purpose of this study is to produce palm oil-based emulsion breaker, assessing the effect of additive application to the emulsion breaker and analyze the performance of the emulsion breaker. This research was conducted by formulating palm oil anionic surfactant in water formation with the addition of co-surfactant additive and co-solvent. Palm oil anionic surfactant-based emulsion breaker with 0.5% concentration in water can reduce 50% of emulsions with the interfacial tension (IFT) of 2.33x10-2 dyne/cm. The addition of co-solvent (toluene: xylene) is able to remove the emulsion formed with a lower IFT namely 10-3 dyne / cm. The resulting emulsion breaker is capable to remove the emulsion between water and oil. The performance test of emulsion breaker show that the emulsion is able to maintain its performance at reservoir temperature with no indicate of plugging and the value generated incremental oil recovery values is 13%.

  5. Strengths and weaknesses of Problem Based Learning from the professional perspective of registered nurses

    Directory of Open Access Journals (Sweden)

    María Cónsul-Giribet

    2014-10-01

    Full Text Available OBJECTIVE: to identify competency strengths and weaknesses as perceived by nursing professionals who graduated with a integrated curriculum and competency-based through Problem Based Learning in small groups.METHOD: an intrinsic case study method was used, which analyzes this innovation through former students (from the first class with three years of professional experience. The data were collected through a questionnaire and discussion groups.RESULTS: the results show that their competency level is valued in a very satisfactory manner. This level paradoxically contrasts with the lack of theoretical knowledge they perceived at the end of their education, when they started working in clinical practice.CONCLUSIONS: the teaching strategy was key to motivate an in-depth study and arouse the desire to know. In addition, Problem Based Learning favors and reinforces the decision to learn, which is that necessary in the course of professional life.

  6. Strengths and weaknesses of Problem Based Learning from the professional perspective of registered nurses 1

    Science.gov (United States)

    Cónsul-Giribet, María; Medina-Moya, José Luis

    2014-01-01

    OBJECTIVE: to identify competency strengths and weaknesses as perceived by nursing professionals who graduated with a integrated curriculum and competency-based through Problem Based Learning in small groups. METHOD: an intrinsic case study method was used, which analyzes this innovation through former students (from the first class) with three years of professional experience. The data were collected through a questionnaire and discussion groups. RESULTS: the results show that their competency level is valued in a very satisfactory manner. This level paradoxically contrasts with the lack of theoretical knowledge they perceived at the end of their education, when they started working in clinical practice. CONCLUSIONS: the teaching strategy was key to motivate an in-depth study and arouse the desire to know. In addition, Problem Based Learning favors and reinforces the decision to learn, which is that necessary in the course of professional life. PMID:25493666

  7. Strengths and weaknesses of Problem Based Learning from the professional perspective of registered nurses.

    Science.gov (United States)

    Cónsul-Giribet, María; Medina-Moya, José Luis

    2014-10-01

    To identify competency strengths and weaknesses as perceived by nursing professionals who graduated with a integrated curriculum and competency-based through Problem Based Learning in small groups. An intrinsic case study method was used, which analyzes this innovation through former students (from the first class) with three years of professional experience. The data were collected through a questionnaire and discussion groups. The results show that their competency level is valued in a very satisfactory manner. This level paradoxically contrasts with the lack of theoretical knowledge they perceived at the end of their education, when they started working in clinical practice. The teaching strategy was key to motivate an in-depth study and arouse the desire to know. In addition, Problem Based Learning favors and reinforces the decision to learn, which is that necessary in the course of professional life.

  8. Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

    Directory of Open Access Journals (Sweden)

    Awatef Ayadi

    2015-08-01

    Full Text Available The synthesis and full characterization of two tetrathiafulvalene-appended azine ligands, namely 2-([2,2’-bi(1,3-dithiolylidene]-4-yl-6-((2,4-dinitrophenylhydrazonomethylpyridine (L1 and 5-([2,2’-bi(1,3-dithiolylidene]-4-yl-2-((2,4-dinitrophenylhydrazonomethylpyridine (L2 are described. The crystal structure of ligand L1 indicates that the ligand is completely planar with the presence of a strong intramolecular N3–H3···O1 hydrogen bonding. Titration experiments with inorganic anions showed that both ligands are suitable candidates for the sensing of fluoride anions. Ligand L2 was reacted with a Re(I cation to yield the corresponding rhenium tricarbonyl complex 3. In the crystal structure of the newly prepared electroactive rhenium complex the TTF is neutral and the rhenium cation is hexacoordinated. The electrochemical behavior of the three compounds indicates that they are promising for the construction of crystalline radical cation salts.

  9. Anion exchange composite membrane based on octa quaternary ammonium Polyhedral Oligomeric Silsesquioxane for alkaline fuel cells

    Science.gov (United States)

    Elumalai, Vijayakumar; Sangeetha, Dharmalingam

    2018-01-01

    A series of novel composite anion exchange membranes were prepared via simple solution casting method using synthesized quaternary ammonium functionalized Polyhedral Oligomeric Silsesquioxane (QA-POSS) with Quaternary polysulfone (QPSU). QA-POSS was synthesized from prepared Cl-POSS and well characterized by FT-IR, NMR, SEM and TEM analyses to confirm the chemical modifications and cubic morphologies. The QA-POSS nano particles have dual role in the membrane providing additional ion conducting groups and reinforcing the membrane in molecular level for the overall improvement of composite membrane. Additionally, the composite membranes were characterized by XRD, SEM, Ion exchange capacity (IEC), water uptake and conductivity to ensure the suitability of its use as an electrolyte in alkaline fuel cell. Finally, membrane electrode assembly (MEA) was fabricated using Pt anode (0.25 mg/cm2), Ag cathode (0.375 mg/cm2) and various synthesized composite membranes, and then it was tested in real time fuel cell setup. The membrane with 15% QA-POSS showed the maximum power density of 321 mW/cm2. The results showed that QA-POSS possess the ability to enhance the performance of the anion exchange membrane significantly.

  10. Long-term effects of dietary anion-cation balance on acid-base status and bone morphology in reproducing ewes.

    Science.gov (United States)

    Espino, L; Guerrero, F; Suarez, M L; Santamarina, G; Goicoa, A; Fidalgo, L E

    2003-12-01

    The beneficial effects of anionic salts on calcium metabolism have been shown by supplementing rations with such salts during the last 3 weeks of pre-partum. However, there are few reports on the effects of anionic salts supplementation for periods of 4 weeks or longer on acid-base status, mineral metabolism and bone morphology. This study was conducted to evaluate the effects of the long-term dietary supplementation of anionic salts on the acid-base status, plasma minerals concentrations and bone morphology in sheep. Twenty-seven twin-bearing sheep were assigned to two experimental groups and a control group, depending on dietary cation-anion difference (DCAD) (+272.6, -88.9 and + 164.5 mEq/kg DM, respectively). Sheep assigned to each dietary treatment received their respective rations beginning 6 weeks prepartum and continuing until 12 days post-partum. Diets containing anionic salts induced a mild metabolic hyperchloraemic acidosis from 1 week pre-partum to 2 days post-partum that was completely compensated by non-respiratory mechanisms. These changes on acid-base status were accompanied by an increase of plasma ionized calcium levels. Plasma total calcium, phosphorus and magnesium concentrations were not affected by dietary treatment. Parathyroid hormone concentrations were related to the concentration of ionized calcium of plasma and were higher in sheep fed the cationic diet. Plasma osteocalcin levels were increased in sheep fed the anionic diet and cortical bone remodelling occurred in all the animals during late pregnancy in light and electron microscopy observation, but was particularly evident in the sheep fed the anionic diet. Bone turnover might be stimulated because of the role of the bone in buffering systemic acidosis. The data suggest that anionic salts ameliorated calcium metabolism around parturition by increasing bone resorption and the concentration of ionised calcium in plasma, possibly mediated by a mild hyperchloraemic metabolic acidosis

  11. EXPLORING WEAK AND OVERLAPPED RETURNS OF A LIDAR WAVEFORM WITH A WAVELET-BASED ECHO DETECTOR

    Directory of Open Access Journals (Sweden)

    C. K. Wang

    2012-08-01

    Full Text Available Full waveform data recording the reflected laser signal from ground objects have been provided by some commercial airborne LIDAR systems in the last few years. Waveform data enable users to explore more information and characteristics of the earth surface than conventional LIDAR point cloud. An important application is to extract extra point clouds from waveform data in addition to the point cloud generated by the online process of echo detection. Some difficult-to-detect points, which may be important to topographic mapping, can be rediscovered from waveform data. The motivation of this study is to explore weak and overlapped returns of a waveform. This paper presents a wavelet-based echo detection algorithm, which is compared with the zero-crossing detection method for evaluation. Some simulated waveforms deteriorated with different noises are made to test the limitations of the detector. The experimental results show that the wavelet-based detector outperformed the zero-crossing detector in both difficult-to-detect cases. The detector is also applied to a real waveform dataset. In addition to the total number of echoes provided by the instrument, the detector found 18% more of echoes. The proposed detector is significant in finding weak and overlapped returns from waveforms.

  12. Study of operating conditions and cell design on the performance of alkaline anion exchange membrane based direct methanol fuel cells

    Science.gov (United States)

    Prakash, G. K. Surya; Krause, Frederick C.; Viva, Federico A.; Narayanan, S. R.; Olah, George A.

    2011-10-01

    Direct methanol fuel cells using an alkaline anion exchange membrane (AAEM) were prepared, studied, and optimized. The effects of fuel composition and electrode materials were investigated. Membrane electrode assemblies fabricated with Tokuyama® AAEM and commercial noble metal catalysts achieved peak power densities between 25 and 168 mW cm-2 depending on the operating temperature, fuel composition, and electrode materials used. Good electrode wettability at the anode was found to be very important for achieving high power densities. The performance of the best AAEM cells was comparable to Nafion®-based cells under similar conditions. Factors limiting the performance of AAEM MEAs were found to be different from those of Nafion® MEAs. Improved electrode kinetics for methanol oxidation in alkaline electrolyte at Pt-Ru are apparent at low current densities. At high current densities, rapid CO2 production converts the hydroxide anions, necessary for methanol oxidation, to bicarbonate and carbonate: consequently, the membrane and interfacial conductivity are drastically reduced. These phenomena necessitate the use of aqueous potassium hydroxide and wettable electrode materials for efficient hydroxide supply to the anode. However, aqueous hydroxide is not needed at the cathode. Compared to AAEM-based fuel cells, methanol fuel cells based on proton-conducting Nafion® retain better performance at high current densities by providing the benefit of carbon dioxide rejection.

  13. Proton Affinities of Anionic Bases:  Trends Across the Periodic Table, Structural Effects, and DFT Validation.

    Science.gov (United States)

    Swart, Marcel; Bickelhaupt, F Matthias

    2006-03-01

    We have carried out an extensive exploration of the gas-phase basicity of archetypal anionic bases across the periodic system using the generalized gradient approximation of density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing proton affinities and related thermochemical quantities:  BP86/QZ4P//BP86/TZ2P is shown to yield a mean absolute deviation of 1.6 kcal/mol for the proton affinity at 0 K with respect to high-level ab initio benchmark data. The main purpose of this work is to provide the proton affinities (and corresponding entropies) at 298 K of the anionic conjugate bases of all main-group-element hydrides of groups 14-17 and periods 2-6. We have also studied the effect of stepwise methylation of the protophilic center of the second- and third-period bases.

  14. Anion-directed assemblies of cationic metal-organic frameworks based on 4,4'-bis(1,2,4-triazole): syntheses, structures, luminescent and anion exchange properties.

    Science.gov (United States)

    Li, Xinxiong; Gong, Yaqiong; Zhao, Huaixia; Wang, Ruihu

    2014-11-17

    Three cationic metal-organic frameworks (MOFs), Ag(btr)·PF6·0.5CH3CN (1), Ag2(btr)2(H2O)·2CF3SO3·H2O (2), and Ag2(btr)2(NO3)·NO3 (3), were prepared from reaction of 4,4'-bis(1,2,4-triazole) (btr) with silver salts containing different anions. Complex 1 is a three-dimensional (3-D) framework constructed from tetrahedral-shaped nanoscale coordination cages with PF6(-) as counteranions. 2 and 3 are 3-D architectures containing 1-D channels, in which charge-balancing CF3SO3(-) and NO3(-) are located in their respective channels. Luminescent emission of 1-3 shows an obvious red shift compared with the btr ligand. Anion exchange studies show that 1 is able to selectively exchange MnO4(-) in aqueous solution with a modest capacity of 0.56 mol mol(-1); the luminescent emission of 1 is quickly quenched upon MnO4(-) exchange.

  15. Track-Before-Detect Algorithm for Weak Extended Target Based on Particle Filter under Clutter Environment

    Directory of Open Access Journals (Sweden)

    Wu Sunyong

    2017-06-01

    Full Text Available The Track-Before-Detect (TBD algorithm based on the particle filter is proposed for weak extended target detection and tracking in low signal to clutter noise radio. The rod-shaped object is analyzed by dividing the cell on range and azimuth under the Weibull clutter. On the basis of a point target, the likelihood function and particle weights can be obtained by the target spread function. In the TBD algorithm, the binary target variable and the target shape parameters is added to the state vector and the scattering points in the sample collection is given based on the particle filter, which can detect and estimate the target state and the shape parameters under the clutter environment. Simulation results show that the stability of the algorithm is very good.

  16. A Carrier Estimation Method Based on MLE and KF for Weak GNSS Signals.

    Science.gov (United States)

    Zhang, Hongyang; Xu, Luping; Yan, Bo; Zhang, Hua; Luo, Liyan

    2017-06-22

    Maximum likelihood estimation (MLE) has been researched for some acquisition and tracking applications of global navigation satellite system (GNSS) receivers and shows high performance. However, all current methods are derived and operated based on the sampling data, which results in a large computation burden. This paper proposes a low-complexity MLE carrier tracking loop for weak GNSS signals which processes the coherent integration results instead of the sampling data. First, the cost function of the MLE of signal parameters such as signal amplitude, carrier phase, and Doppler frequency are used to derive a MLE discriminator function. The optimal value of the cost function is searched by an efficient Levenberg-Marquardt (LM) method iteratively. Its performance including Cramér-Rao bound (CRB), dynamic characteristics and computation burden are analyzed by numerical techniques. Second, an adaptive Kalman filter is designed for the MLE discriminator to obtain smooth estimates of carrier phase and frequency. The performance of the proposed loop, in terms of sensitivity, accuracy and bit error rate, is compared with conventional methods by Monte Carlo (MC) simulations both in pedestrian-level and vehicle-level dynamic circumstances. Finally, an optimal loop which combines the proposed method and conventional method is designed to achieve the optimal performance both in weak and strong signal circumstances.

  17. Finite Elements Based on Strong and Weak Formulations for Structural Mechanics: Stability, Accuracy and Reliability

    Directory of Open Access Journals (Sweden)

    Francesco Tornabene

    2017-07-01

    Full Text Available The authors are presenting a novel formulation based on the Differential Quadrature (DQ method which is used to approximate derivatives and integrals. The resulting scheme has been termed strong and weak form finite elements (SFEM or WFEM, according to the numerical scheme employed in the computation. Such numerical methods are applied to solve some structural problems related to the mechanical behavior of plates and shells, made of isotropic or composite materials. The main differences between these two approaches rely on the initial formulation – which is strong or weak (variational – and the implementation of the boundary conditions, that for the former include the continuity of stresses and displacements, whereas in the latter can consider the continuity of the displacements or both. The two methodologies consider also a mapping technique to transform an element of general shape described in Cartesian coordinates into the same element in the computational space. Such technique can be implemented by employing the classic Lagrangian-shaped elements with a fixed number of nodes along the element edges or blending functions which allow an “exact mapping” of the element. In particular, the authors are employing NURBS (Not-Uniform Rational B-Splines for such nonlinear mapping in order to use the “exact” shape of CAD designs.

  18. Small molecule-based ratiometric fluorescence probes for cations, anions, and biomolecules.

    Science.gov (United States)

    Lee, Min Hee; Kim, Jong Seung; Sessler, Jonathan L

    2015-07-07

    Quantitative determination of specific analytes is essential for a variety of applications ranging from life sciences to environmental monitoring. Optical sensing allows non-invasive measurements within biological milieus, parallel monitoring of multiple samples, and less invasive imaging. Among the optical sensing methods currently being explored, ratiometric fluorescence sensing has received particular attention as a technique with the potential to provide precise and quantitative analyses. Among its advantages are high sensitivity and inherent reliability, which reflect the self-calibration provided by monitoring two (or more) emissions. A wide variety of ratiometric sensing probes using small fluorescent molecules have been developed for sensing, imaging, and biomedical applications. In this research highlight, we provide an overview of the design principles underlying small fluorescent probes that have been applied to the ratiometric detection of various analytes, including cations, anions, and biomolecules in solution and in biological samples. This highlight is designed to be illustrative, not comprehensive.

  19. Sodium-ion electrolytes based on ionic liquids: a role of cation-anion hydrogen bonding.

    Science.gov (United States)

    Chaban, Vitaly V; Andreeva, Nadezhda A

    2016-08-01

    Recent success of the sodium-ion batteries fosters an academic interest for their investigation. Room-temperature ionic liquids (RTILs) constitute universal solvents providing non-volatility and non-flammability to electrolytes. In the present work, we consider four families of RTILs as prospective solvents for NaBF4 and NaNO3 with an inorganic salt concentration of 25 and 50 mol%. We propose a methodology to rate RTILs according to their solvation capability using parameters of the computed radial distribution functions. Hydrogen bonds between the cations and the anions of RTILs were found to indirectly favor sodium solvation, irrespective of the particular RTIL and its concentration. The best performance was recorded in the case of cholinium nitrate. The reported observations and correlations of ionic structures and properties offer important assistance to an emerging field of sodium-ion batteries. Graphical Abstract Sodium-ion electrolytes.

  20. A novel silica based click lysine anion exchanger for ion exchange chromatography.

    Science.gov (United States)

    Guo, Hongyue; Chu, Changhu; Li, Yan; Yang, Bingcheng; Liang, Xinmiao

    2011-12-21

    Ion chromatography (IC) is one of the most powerful analysis technologies for the determination of charged compounds. A novel click lysine stationary phase was prepared via Cu(I) catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) and applied to the analysis of inorganic ions. The chromatographic evaluation demonstrated good performance (e.g. the plate number of thiocyanate is ∼50,000 plates m(-1)) and effective separation ability for the common inorganic anions with aqueous Na(2)SO(4) eluent. The separation mechanism was observed to be mainly dominated by ion exchange interaction. The retention of these analytes is highly dependent on the pH value of eluent. Compared with the lysine stationary phase prepared via the conventional manner, the click lysine exchanger demonstrated shorter retention time and better ion separation characteristics under the same chromatographic conditions, which is a great advantage for rapid separation and analysis of inorganic ions.

  1. Dithieno[3,2-a:2',3'-c]phenazine-based Chemical Probe for Anions: A Spectroscopic Study of Binding

    KAUST Repository

    El-Assaad, Tarek H.

    2015-04-27

    The synthesis of a new anion-responsive molecule N,N\\'-(2,5-bis(4-(tert-butyl)phenyl)dithieno[3,2-a:2\\',3\\'-c]phenazine-9,10-diyl)bis(4-methylbenzenesulfonamide) (1) is reported. The sensitivities of the spectroscopic properties of 1 in the presence of various anions were examined using UV-vis absorption spectroscopy, fluorescence and 1H NMR titration experiments. Strong binding of 1 to carboxylate, cyanide, fluoride and dihydrogen phosphate anions results in an increase in quantum yield for emission of 1, and changes in its 1H NMR chemical shifts. A significant electrostatic interaction of the tetrabutylammonium cation with 1, upon strong binding with the counter anion, was also indicated by the chemical shifts observed in the 1H NMR titrations. Binding constants of 1 to anions are also calculated based on the binding isotherms derived from NMR and UV-Vis titrations. DFT calculations show that the anion does not significantly impact the HOMO/LUMO levels (and subsequently the S0 -> S1 transition), but rather changes the strength of the S0 -> S2 transition, which accounts for the observed changes in the UV-vis spectra.

  2. Weak relativity

    CERN Document Server

    Selleri, Franco

    2015-01-01

    Weak Relativity is an equivalent theory to Special Relativity according to Reichenbach’s definition, where the parameter epsilon equals to 0. It formulates a Neo-Lorentzian approach by replacing the Lorentz transformations with a new set named “Inertial Transformations”, thus explaining the Sagnac effect, the twin paradox and the trip from the future to the past in an easy and elegant way. The cosmic microwave background is suggested as a possible privileged reference system. Most importantly, being a theory based on experimental proofs, rather than mutual consensus, it offers a physical description of reality independent of the human observation.

  3. A fast weak motif-finding algorithm based on community detection in graphs.

    Science.gov (United States)

    Jia, Caiyan; Carson, Matthew B; Yu, Jian

    2013-07-17

    Identification of transcription factor binding sites (also called 'motif discovery') in DNA sequences is a basic step in understanding genetic regulation. Although many successful programs have been developed, the problem is far from being solved on account of diversity in gene expression/regulation and the low specificity of binding sites. State-of-the-art algorithms have their own constraints (e.g., high time or space complexity for finding long motifs, low precision in identification of weak motifs, or the OOPS constraint: one occurrence of the motif instance per sequence) which limit their scope of application. In this paper, we present a novel and fast algorithm we call TFBSGroup. It is based on community detection from a graph and is used to discover long and weak (l,d) motifs under the ZOMOPS constraint (zero, one or multiple occurrence(s) of the motif instance(s) per sequence), where l is the length of a motif and d is the maximum number of mutations between a motif instance and the motif itself. Firstly, TFBSGroup transforms the (l, d) motif search in sequences to focus on the discovery of dense subgraphs within a graph. It identifies these subgraphs using a fast community detection method for obtaining coarse-grained candidate motifs. Next, it greedily refines these candidate motifs towards the true motif within their own communities. Empirical studies on synthetic (l, d) samples have shown that TFBSGroup is very efficient (e.g., it can find true (18, 6), (24, 8) motifs within 30 seconds). More importantly, the algorithm has succeeded in rapidly identifying motifs in a large data set of prokaryotic promoters generated from the Escherichia coli database RegulonDB. The algorithm has also accurately identified motifs in ChIP-seq data sets for 12 mouse transcription factors involved in ES cell pluripotency and self-renewal. Our novel heuristic algorithm, TFBSGroup, is able to quickly identify nearly exact matches for long and weak (l, d) motifs in DNA

  4. Anion-responsive supramolecular gels.

    Science.gov (United States)

    Maeda, Hiromitsu

    2008-01-01

    Supramolecular gels that change their state or structure in response to anion stimuli have been highlighted. Only a few examples exist of such supramolecular gels, the structures and properties of which can be controlled and modulated by interactions with anions. To form anion-responsive dimensionally-controlled organized structures, the constituent low-molecular-weight gelator molecules must act as anion receptors by possessing one or more of van der Waals interaction units (aliphatic chains), stacking pi planes, hydrogen-bonding sites, and metal-coordination units. This Concept focuses on the gelation and transition behaviors of amide- and urea-based anion-stimulated systems, metal-coordinated systems, and novel acyclic pi-conjugated oligopyrroles that act as "molecular flippers."

  5. 3D modeling method for computer animate based on modified weak structured light method

    Science.gov (United States)

    Xiong, Hanwei; Pan, Ming; Zhang, Xiangwei

    2010-11-01

    A simple and affordable 3D scanner is designed in this paper. Three-dimensional digital models are playing an increasingly important role in many fields, such as computer animate, industrial design, artistic design and heritage conservation. For many complex shapes, optical measurement systems are indispensable to acquiring the 3D information. In the field of computer animate, such an optical measurement device is too expensive to be widely adopted, and on the other hand, the precision is not as critical a factor in that situation. In this paper, a new cheap 3D measurement system is implemented based on modified weak structured light, using only a video camera, a light source and a straight stick rotating on a fixed axis. For an ordinary weak structured light configuration, one or two reference planes are required, and the shadows on these planes must be tracked in the scanning process, which destroy the convenience of this method. In the modified system, reference planes are unnecessary, and size range of the scanned objects is expanded widely. A new calibration procedure is also realized for the proposed method, and points cloud is obtained by analyzing the shadow strips on the object. A two-stage ICP algorithm is used to merge the points cloud from different viewpoints to get a full description of the object, and after a series of operations, a NURBS surface model is generated in the end. A complex toy bear is used to verify the efficiency of the method, and errors range from 0.7783mm to 1.4326mm comparing with the ground truth measurement.

  6. BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis

    Directory of Open Access Journals (Sweden)

    Muhammad Imran Khan

    2017-03-01

    Full Text Available To reduce the environmental impact of acids present in various industrial wastes, improved and robust anion exchange membranes (AEMs are highly desired. Moreover, they should exhibit high retention of salts, fast acid permeation and they should be able to operate with low energy input. In this work, AEMs are prepared using a facile solution-casting from brominated poly-(2,6-dimethyl-1,4-phenylene oxide (BPPO and increasing amounts of 2-phenylimidazole (PI. Neither quaternary ammonium salts, nor ionic liquids and silica-containing compounds are involved in the synthesis. The prepared membranes showed an ion exchange capacity of 1.1–1.8 mmol/g, a water uptake of 22%–47%, a linear expansion ratio of 1%–6% and a tensile strength of 0.83–10.20 MPa. These membranes have potential for recovering waste acid via diffusion dialysis, as the acid dialysis coefficient (UH at room temperature for HCl is in the range of 0.006–0.018 m/h while the separation factor (S is in the range of 16–28, which are higher than commercial DF-120B membranes (UH = 0.004 m/h, S = 24.

  7. Performance testing of grout-based waste forms for the solidification of anion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, I.L.; Bostick, W.D.

    1990-10-01

    The solidification of spent ion exchanges resins in a grout matrix as a means of disposing of spent organic resins produced in the nuclear fuel cycle has many advantages in terms of process simplicity and economy, but associated with the process is the potential for water/cement/resins to interact and degrade the integrity of the waste form solidified. Described in this paper is one possible solution to preserving the integrity of these solidified waste forms: the encapsulation of beaded anion exchange resins in grout formulations containing ground granulated blast furnace slag, Type I-II (mixed) portland cement, and additives (clays, amorphous silica, silica fume, and fly ash). The results of the study reported herein show the cured waste form tested has a low leach rate for nitrate ion from the resin (and a low leach rate is inferred for Tc-99) and acceptable durability as assessed by the water immersion and freezing/thawing test protocols. The results also suggest a tested surrogate waste form prepared in vinyl ester styrene binder performs satisfactorily against the wetting/drying criterion, and it should offer additional insight into future work on the solidification of spent organic resins. 26 refs., 4 figs., 5 tabs.

  8. A Nanotechnology-Ready Computing Scheme based on a Weakly Coupled Oscillator Network

    Science.gov (United States)

    Vodenicarevic, Damir; Locatelli, Nicolas; Abreu Araujo, Flavio; Grollier, Julie; Querlioz, Damien

    2017-03-01

    With conventional transistor technologies reaching their limits, alternative computing schemes based on novel technologies are currently gaining considerable interest. Notably, promising computing approaches have proposed to leverage the complex dynamics emerging in networks of coupled oscillators based on nanotechnologies. The physical implementation of such architectures remains a true challenge, however, as most proposed ideas are not robust to nanotechnology devices’ non-idealities. In this work, we propose and investigate the implementation of an oscillator-based architecture, which can be used to carry out pattern recognition tasks, and which is tailored to the specificities of nanotechnologies. This scheme relies on a weak coupling between oscillators, and does not require a fine tuning of the coupling values. After evaluating its reliability under the severe constraints associated to nanotechnologies, we explore the scalability of such an architecture, suggesting its potential to realize pattern recognition tasks using limited resources. We show that it is robust to issues like noise, variability and oscillator non-linearity. Defining network optimization design rules, we show that nano-oscillator networks could be used for efficient cognitive processing.

  9. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

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

  10. Effect of anionic salts on some blood and urine minerals, acid-base balance and udder oedema of dry pregnant cows

    Directory of Open Access Journals (Sweden)

    S. TAURIAINEN

    2008-12-01

    Full Text Available The objective of this study was to determine the effect of an anionic diet on mineral metabolism, acid-base status and udder oedema of dairy cows fed grass silage based diets during the dry period. Eighteen pregnant, non-lactating Friesian cows were divided randomly into two groups according to their expected calving date. Dietary cation-anion balance (DCAB, calculated as mill equivalents [(Na + + K + - (Cl - + S 2- ], for high DCAB (control and low DCAB treatments were +254 and -41 mEq kg -1 dry matter (DM, respectively. Anionic salts were ammonium chloride (NH 4 Cl, magnesium chloride (MgCl 2 and magnesium sulphate (MgSO 4 . Cows received grass silage (5.2 kg DM, hay (0.9 kg DM and a concentrate mixture (2.7 kg DM until calving. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, 1 day and 1 week after calving. Udder oedema was evaluated by a quantitative and a subjective method. Acidification resulted in a marked decrease in urinary pH, increased urinary Ca excretion and a change in blood acidbase balance. Blood Ca 2+ and plasma Ca tot concentrations were more stable at parturition for the anionic group, although such differences were not statistically significant. Anionic salts (DCAB -41 mEq kg -1 DM did not cause udder oedema in experimental cows.;

  11. Finite-key analysis for quantum key distribution with weak coherent pulses based on Bernoulli sampling

    Science.gov (United States)

    Kawakami, Shun; Sasaki, Toshihiko; Koashi, Masato

    2017-07-01

    An essential step in quantum key distribution is the estimation of parameters related to the leaked amount of information, which is usually done by sampling of the communication data. When the data size is finite, the final key rate depends on how the estimation process handles statistical fluctuations. Many of the present security analyses are based on the method with simple random sampling, where hypergeometric distribution or its known bounds are used for the estimation. Here we propose a concise method based on Bernoulli sampling, which is related to binomial distribution. Our method is suitable for the Bennett-Brassard 1984 (BB84) protocol with weak coherent pulses [C. H. Bennett and G. Brassard, Proceedings of the IEEE Conference on Computers, Systems and Signal Processing (IEEE, New York, 1984), Vol. 175], reducing the number of estimated parameters to achieve a higher key generation rate compared to the method with simple random sampling. We also apply the method to prove the security of the differential-quadrature-phase-shift (DQPS) protocol in the finite-key regime. The result indicates that the advantage of the DQPS protocol over the phase-encoding BB84 protocol in terms of the key rate, which was previously confirmed in the asymptotic regime, persists in the finite-key regime.

  12. Total phenol analysis of weakly supported water using a laccase-based microband biosensor.

    Science.gov (United States)

    Sekretaryova, Alina N; Volkov, Anton V; Zozoulenko, Igor V; Turner, Anthony P F; Vagin, Mikhail Yu; Eriksson, Mats

    2016-02-11

    The monitoring of phenolic compounds in wastewaters in a simple manner is of great importance for environmental control. Here, a novel screen printed laccase-based microband array for in situ, total phenol estimation in wastewaters and for water quality monitoring without additional sample pre-treatment is presented. Numerical simulations using the finite element method were utilized for the characterization of micro-scale graphite electrodes. Anodization followed by covalent modification was used for the electrode functionalization with laccase. The functionalization efficiency and the electrochemical performance in direct and catechol-mediated oxygen reduction were studied at the microband laccase electrodes and compared with macro-scale electrode structures. The reduction of the dimensions of the enzyme biosensor, when used under optimized conditions, led to a significant improvement in its analytical characteristics. The elaborated microsensor showed fast responses towards catechol additions to tap water - a weakly supported medium - characterized by a linear range from 0.2 to 10 μM, a sensitivity of 1.35 ± 0.4 A M(-1) cm(-2) and a dynamic range up to 43 μM. This enhanced laccase-based microsensor was used for water quality monitoring and its performance for total phenol analysis of wastewater samples from different stages of the cleaning process was compared to a standard method. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Atomic structure of defects in anion-deficient perovskite-based ferrites with a crystallographic shear structure.

    Science.gov (United States)

    Batuk, Maria; Turner, Stuart; Abakumov, Artem M; Batuk, Dmitry; Hadermann, Joke; Van Tendeloo, Gustaaf

    2014-02-17

    Crystallographic shear (CS) planes provide a new structure-generation mechanism in the anion-deficient perovskites containing lone-pair cations. Pb2Sr2Bi2Fe6O16, a new n = 6 representative of the A(n)B(n)O(3n-2) homologous series of the perovskite-based ferrites with the CS structure, has been synthesized using the solid-state technique. The structure is built of perovskite blocks with a thickness of four FeO6 octahedra spaced by double columns of FeO5 edge-sharing distorted tetragonal pyramids, forming 1/2[110](101)p CS planes (space group Pnma, a = 5.6690(2) Å, b = 3.9108(1) Å, c = 32.643(1) Å). Pb2Sr2Bi2Fe6O16 features a wealth of microstructural phenomena caused by the flexibility of the CS planes due to the variable ratio and length of the constituting fragments with {101}p and {001}p orientation. This leads to the formation of "waves", "hairpins", "Γ-shaped" defects, and inclusions of the hitherto unknown layered anion-deficient perovskites Bi2(Sr,Pb)Fe3O8.5 and Bi3(Sr,Pb)Fe4O11.5. Using a combination of diffraction, imaging, and spectroscopic transmission electron microscopy techniques this complex microstructure was fully characterized, including direct determination of positions, chemical composition, and coordination number of individual atomic species. The complex defect structure makes these perovskites particularly similar to the CS structures in ReO3-type oxides. The flexibility of the CS planes appears to be a specific feature of the Sr-based system, related to the geometric match between the SrO perovskite layers and the {100}p segments of the CS planes.

  14. Evaluation of acid-base disorders in dogs and cats presenting to an emergency room. Part 2: comparison of anion gap, strong ion gap, and semiquantitative analysis.

    Science.gov (United States)

    Hopper, Kate; Epstein, Steven E; Kass, Philip H; Mellema, Matthew S

    2014-01-01

    To compare the diagnostic performance of the anion gap (AG) with 2 physicochemical approaches to identify unmeasured anions. Prospective cohort study. University teaching hospital. Eighty-four dogs and 14 cats presenting to a university teaching hospital emergency room. All dogs and cats in which venous blood samples for acid-base, lactate, and serum biochemical analysis were all collected within 60 minutes of each other, over a 5-month enrollment period. Unmeasured anions were quantified using each of three approaches: the anion gap (AG), strong ion gap (SIG), and a semiquantitative approach (XA). An increased AG metabolic acidosis was evident in 34/98 of cases. The Stewart approach identified an increased SIG acidosis in 49/98 of cases. There was a strong correlation between SIG and AG (r = 0.89; P small animal emergency room patients and physiochemical approaches identified more animals with unmeasured anions than the traditional AG calculation. Further studies are needed to determine if the results of the physicochemical approach improves clinical management and warrants the associated increases in cost and complexity. © Veterinary Emergency and Critical Care Society 2014.

  15. Effect of dietary cation-anion difference on measures of acid-base physiology and performance in beef cattle.

    Science.gov (United States)

    Hersom, M J; Hansen, G R; Arthington, J D

    2010-01-01

    Dietary constituents can affect cow acid-base physiology and uterine pH. Dietary cation-anion difference (DCAD) has been shown to affect cow acid-base physiology, but the effect on uterine pH has not been demonstrated. The objective of this work was to determine if DCAD [(Na + K + 0.15Ca + 0.15Mg) - (Cl + 0.60S + 0.50P)] could affect cow DMI, acid-base physiology, and uterine pH, and second, to determine if dietary supplements could alleviate any negative effects of DCAD on these variables. In Exp. 1, 21 cows were utilized to determine the effect of a negative DCAD (-0.9 mEq/100 g of DM; low-DCAD) or positive DCAD (+25.0 mEq/100 g of DM; high-DCAD) diet on cow BW, DMI, and pH of blood, urine, and uterine flush fluid. In Exp. 2, 21 cows were randomly allotted to 1 of 3 treatments: control (-3.1 mEq/100 g of DM), molasses (+2.9 mEq/100 g of DM), or molasses+buffer (+25.8 mEq/100 g of DM) to determine if supplemental liquid molasses or liquid molasses with a buffer could alleviate the effects of a negative DCAD, forage-based diet. Cows were individually fed their respective diets for 42 d in both experiments. Cow BW, blood, urine, and uterine flush were collected on d 0, 21, and 42 during both experiments. Cow ADG was not different (P = 0.71) in Exp. 1 or Exp. 2 (P = 0.47). Hay DMI did not differ (P differ (P = 0.39) among treatments. In Exp. 1, a treatment x day interaction (P differences (P > 0.14) among treatments for blood, pH, base excess, pCO(2), or uterine flush pH. Urine pH exhibited a treatment x day interaction (P cation-anion difference and the use of molasses-based supplements had minimal effect on forage-fed beef cow DMI. However, DCAD has the capacity to alter forage-fed beef cow acid-base physiology and potentially affect uterine physiology.

  16. A New Method for Weak Fault Feature Extraction Based on Improved MED

    Directory of Open Access Journals (Sweden)

    Junlin Li

    2018-01-01

    Full Text Available Because of the characteristics of weak signal and strong noise, the low-speed vibration signal fault feature extraction has been a hot spot and difficult problem in the field of equipment fault diagnosis. Moreover, the traditional minimum entropy deconvolution (MED method has been proved to be used to detect such fault signals. The MED uses objective function method to design the filter coefficient, and the appropriate threshold value should be set in the calculation process to achieve the optimal iteration effect. It should be pointed out that the improper setting of the threshold will cause the target function to be recalculated, and the resulting error will eventually affect the distortion of the target function in the background of strong noise. This paper presents an improved MED based method of fault feature extraction from rolling bearing vibration signals that originate in high noise environments. The method uses the shuffled frog leaping algorithm (SFLA, finds the set of optimal filter coefficients, and eventually avoids the artificial error influence of selecting threshold parameter. Therefore, the fault bearing under the two rotating speeds of 60 rpm and 70 rpm is selected for verification with typical low-speed fault bearing as the research object; the results show that SFLA-MED extracts more obvious bearings and has a higher signal-to-noise ratio than the prior MED method.

  17. Ionic liquid based on α-amino acid anion and N7,N9-dimethylguaninium cation ([dMG][AA]): theoretical study on the structure and electronic properties.

    Science.gov (United States)

    Shakourian-Fard, Mehdi; Fattahi, Alireza; Bayat, Ahmad

    2012-06-07

    The interactions between five amino acid based anions ([AA](-) (AA = Gly, Phe, His, Try, and Tyr)) and N7,N9-dimethylguaninium cation ([dMG](+)) have been investigated by the hybrid density functional theory method B3LYP together with the basis set 6-311++G(d,p). The calculated interaction energy was found to decrease in magnitude with increasing side-chain length in the amino acid anion. The interaction between the [dMG](+) cation and [AA](-) anion in the most stable configurations of ion pairs is a hydrogen bonding interaction. These hydrogen bonds (H bonds) were analyzed by the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis. Finally, several correlations between electron densities in bond critical points of hydrogen bonds and interaction energy as well as vibrational frequencies in the most stable configurations of ion pairs have been checked.

  18. The impact of dietary cation anion difference (DCAD) on the acid-base balance and calcium metabolism of non-lactating, non-pregnant dairy cows fed equal amounts of different anionic salts.

    Science.gov (United States)

    Gelfert, Carl-Christian; Leonie Loeffler, S; Frömer, Sven; Engel, Maike; Hartmann, Helmut; Männer, Klaus; Baumgartner, Walter; Staufenbiel, Rudolf

    2007-08-01

    We evaluated the impact of the dietary cation-anion difference (DCAD) on the influence of anionic salts (AS) on the metabolism of dairy cows using a study-design that included control of feed intake. Ten mature, non-lactating, non-pregnant, Holstein-Friesian-crossbreed cows received 2000 mEq of either one of the seven anionic salts tested, two combinations of the anionic salts or water as control via a rumen cannula. Salts and controls were assigned in a 10x10 Latin square design. Whole blood, serum and urine samples were taken during treatment (TP) and washout period. Samples of whole blood were tested for pH, base-excess and bicarbonate concentrations. In urine, pH and net acid-base excretion (NABE) were analysed. Calcium was measured in serum and urine. According to the different batches of hay, five groups of DCAD were created regarding cluster analysis. Changes in urine and blood parameters were statistically analysed for each DCAD group separately. The different DCAD had an impact on the amount of change in acid-base balance (ABB) and calcium metabolism and for how long these changes lasted. In the DCAD group receiving the highest amount of AS (239 mEq/kg dry matter with AS), changes of ABB were only noticeable in urine and these changes only differed from day zero in the first week of TP (Pdiffer significantly (Pdiffered clearly from day zero (Pdifferences were very small and only differed from day zero on a few TP days. We conclude that the DCAD of a dairy cow's diet has an important impact on the effect of AS on ABB and calcium metabolism with respect to the duration and amount of change. The target regions of DCAD should be clearly below 100 mEq/kg dry matter to ensure the desired effect on ABB and calcium metabolism. Extremely negative DCAD should be avoided to minimize the risk of clinical acidosis induced by AS.

  19. The weak π − π interaction originated resonant tunneling and fast switching in the carbon based electronic devices

    Directory of Open Access Journals (Sweden)

    Jun He

    2012-03-01

    Full Text Available By means of the nonequilibrium Green's functions and the density functional theory, we have investigated the electronic transport properties of C60 based electronic device with different intermolecular interactions. It is found that the electronic transport properties vary with the types of the interaction between two C60 molecules. A fast electrical switching behavior based on negative differential resistance has been found when two molecules are coupled by the weak π − π interaction. Compared to the solid bonding, the weak interaction is found to induce resonant tunneling, which is responsible for the fast response to the applied electric field and hence the velocity of switching.

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

    Science.gov (United States)

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

    2017-01-27

    Novel pellicular poly(styrene-divinylbenzene)-based (PS-DVB) anion exchangers with covalently-bonded hyperbranched functional ion-exchange layers containing negatively charged functionalities are obtained and examined. The hyperbranched coating is created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE), and amination of the terminal epoxide rings with methylamine (MA) or glycine (Gly). The influence of the position and the number of the layers with glycine, as well as of the total number of the layers of amine in the coating on the chromatographic properties of the obtained stationary phases is investigated. Chromatographic performance of the obtained stationary phases is evaluated using the model mixtures of inorganic and organic anions with hydroxide eluent. It is shown that the best selectivity toward weakly retained organic acids and oxyhalides is possessed by the anion exchanger obtained after 5 modification cycles, with glycine being used in the first one. Such anion exchanger packed in 25-cm long column is capable of separating 22 anions in 58min including 7 standard anions, mono-, di- and trivalent organic acids, oxyhalides, and some other double- and triple-charged anions. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Evaluation of the strengths and weaknesses of community-based education from the viewpoint of students.

    Science.gov (United States)

    Mokhtarpour, Sedigheh; Amini, Mitra; Mousavinezhad, Houri; Choobineh, Alireza; Nabeiei, Parisa

    2016-10-01

    Responsive medicine is an appropriate training method which trains the graduates who can act effectively in initial and secondary aspects of health issues in the society. This was a cross-sectional descriptive-analytic study which was done using quantitative method. The target population of this study was all the students of the Nutrition and Health School of Shiraz University of Medical Sciences. The sample was randomly selected in this study and 75 students were selected based on the methodologist's comments and similar studies and random-number table from a list obtained from the school's department of education. This questionnaire was a researcher-made one which consisted of 23 questions in 2 sections with 21 closed-ended questions and 2 open-ended questions; 70 questionnaires were completed correctly. The closed-ended questions had 4 aspects (completely agree to completely disagree) answered in 5-point Likert scale type. Its face validity was confirmed by 4 faculty members. The construct validity of the questionnaire was analyzed by factor analysis test and its reliability was assessed by a pilot on 20 students with a Cronbach's alpha of 0.85. The data were analyzed using descriptive statistical tests (mean, standard deviation, …) and the Pearson coefficient (pstrengths were the use of logbooks as a guide and determining the minimum training; of the weaknesses was the mismatch between the theoretical education and the practical activities. Also, developing the minimum training that an expert should know and using the common topics related to theoretical education were the most important points mentioned by the respondents. The educational planning of the authorities for keeping the balance of the theoretical training with the practical activities and giving opportunities to the trainee or intern to face diseases and the common problems of the community seems to be necessary.

  2. Transport of imidazolium-based ionic liquids with different anion/cation species in sand/soil columns.

    Science.gov (United States)

    Dong, Zhiqiang; Wei, Li; Xu, Suwei; Sun, Jingwei; Shi, Xinyi; Qiu, Yuping

    2018-01-01

    Ionic liquids (ILs) have been widely used as environmentally friendly solvents to replace volatile organic solvents in the chemistry industries. They have a high water solubility and potential risk to organisms in the soil-water environment. At present, most studies focused on the batch sorption of ILs in soil and neglected the investigation of IL transports in soil, which results in a lack of understanding of the structure-dependent mobility of ILs in the environment. Laboratory-scale sand/soil column experiments were performed to study the transport of imidazolium-based ILs, such as [C4mim][OTF], [C4mim][TOS], [C4mim][MeSO3], [C4mim][BF4], [C2mim][BF4], and [C6mim][BF4] including different counteranions and alkyl chain lengths of IL cations. Batch experiments were also carried out to compare the difference of sorption distribution coefficient (Kd) between the batch and column experiments. A one-dimensional convective-dispersive model using CXTFIT code was created based on the measured breakthrough curves (BTCs) to estimate the column transport parameters. For the anion, [BF4-], the Kd of ILs in both batch and column experiments increased with increasing alkyl chain lengths of the IL cation. In batch tests, counteranions showed no influence on the Kd of [C4mim][OTF], [C4mim][TOS], [C4mim][MeSO3], [C4mim][BF4], [C2mim][BF4], and [C6mim][BF4]. However, in column tests, the BTCs of 1-butyl-3-methylimidazolium-based ILs were anion dependent as evidenced by the change of retardation factor (R) for different counteranions. Furthermore, the effects of transport distance (11cm, 15cm, 19cm, and 24cm) on the mobility of ILs were estimated. The longer distances signified an increase in the contact time and more binding sites for ILs and therefore, the smoother shapes of BTCs in column experiments. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. High Weak Order Methods for Stochastic Differential Equations Based on Modified Equations

    KAUST Repository

    Abdulle, Assyr

    2012-01-01

    © 2012 Society for Industrial and Applied Mathematics. Inspired by recent advances in the theory of modified differential equations, we propose a new methodology for constructing numerical integrators with high weak order for the time integration of stochastic differential equations. This approach is illustrated with the constructions of new methods of weak order two, in particular, semi-implicit integrators well suited for stiff (meansquare stable) stochastic problems, and implicit integrators that exactly conserve all quadratic first integrals of a stochastic dynamical system. Numerical examples confirm the theoretical results and show the versatility of our methodology.

  4. Acid/base bifunctional carbonaceous nanomaterial with large surface area: Preparation, characterization, and adsorption properties for cationic and anionic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kai; Ma, Chun–Fang; Ling, Yuan; Li, Meng [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Gao, Qiang, E-mail: gaoqiang@cug.edu.cn [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geo Materials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Luo, Wen–Jun, E-mail: heartnohome@yahoo.com.cn [Department of Chemistry, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China)

    2015-07-15

    Nanostructured carbonaceous materials are extremely important in the nano field, yet developing simple, mild, and “green” methods that can make such materials possess large surface area and rich functional groups on their surfaces still remains a considerable challenge. Herein, a one-pot and environment-friendly method, i.e., thermal treatment (180 °C; 18 h) of water mixed with glucose and chitosan (CTS), has been proposed. The resultant carbonaceous nanomaterials were characterized by field emitting scanning electron microscope, N{sub 2} adsorption/desorption, Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, and zeta-potential analysis. It was found that, in contrast to the conventional hydrothermally carbonized product from pure glucose, with low surface area (9.3 m{sup 2} g{sup −1}) and pore volume (0.016 cm{sup 3} g{sup −1}), the CTS-added carbonaceous products showed satisfactory textural parameters (surface area and pore volume up to 254 m{sup 2} g{sup −1} and 0.701 cm{sup 3} g{sup −1}, respectively). Moreover, it was also interestingly found that these CTS-added carbonaceous products possessed both acidic (–COOH) and basic (–NH{sub 2}) groups on their surfaces. Taking the advantages of large surface area and –COOH/–NH{sub 2} bifunctional surface, the carbonaceous nanomaterials exhibited excellent performance for adsorptions of cationic compound (i.e., methylene blue) at pH 10 and anionic compound (i.e., acid red 18) at pH 2, respectively. This work not only provides a simple and green route to prepare acid/base bifunctional carbonaceous nanomaterials with large surface area but also well demonstrates their potential for application in adsorption. - Highlights: • A simple and green method was proposed to prepare carbon nanomaterials. • The carbon product showed acid/base bifunctional surface with large surface area. • The carbon material could efficiently adsorb both cationic and anionic compounds.

  5. Pay as you throw: strengths and weaknesses of weight-based billing in household waste collection systems in Sweden.

    Science.gov (United States)

    Dahlén, Lisa; Lagerkvist, Anders

    2010-01-01

    Householders' response to weight-based billing for the collection of household waste was investigated with the aim of providing decision support for waste management policies. Three questions were addressed: How much and what kind of information on weight-based billing is discernible in generic Swedish waste collection statistics? Why do local authorities implement weight-based billing, and how do they perceive the results? and, Which strengths and weaknesses of weight-based billing have been observed on the local level? The study showed that municipalities with pay-by-weight schemes collected 20% less household waste per capita than other municipalities. Surprisingly, no part of this difference could be explained by higher recycling rates. Nevertheless, the majority of waste management professionals were convinced that recycling had increased as a result of the billing system. A number of contradicting strengths and weaknesses of weight-based billing were revealed.

  6. An IUPAC-based approach to estimate the detection limit in co-extraction-based optical sensors for anions with sigmoidal response calibration curves.

    Science.gov (United States)

    Fernández-Ramos, M D; Cuadros-Rodríguez, L; Arroyo-Guerrero, E; Capitán-Vallvey, L F

    2011-11-01

    An approach based on IUPAC methodology to estimate the limit of detection of bulk optode-based analytical methods for anions has been developed. The traditional IUPAC methodology for calculating the detection limit was modified to be adapted to particular cases where the calibration curves have a sigmoidal profile. Starting from the different full theoretical models for every co-extraction mechanism of the analyte in the membrane in bulk optodes, several particular simplified models at low analyte concentration were obtained and validated. The slope of the calibration curve at low analyte concentration was calculated from the first derivative of the simplified equation and, subsequently, the detection limit was estimated. This fitted-for-purpose estimation strategy was applied to anion quantification for in-house bulk optode-based analytical methods, and the estimated limits of detection were compared with those obtained by applying classical geometrical methodology. This way of establishing the detection limit yields values that maintain their true statistical and probabilistic aspects. It can be easily applied to any analytical system which yields non-linear calibration curves at low analyte concentration.

  7. Quantitative physicochemical analysis of acid-base balance and clinical utility of anion gap and strong ion gap in 806 neonatal calves with diarrhea.

    Science.gov (United States)

    Trefz, F M; Constable, P D; Lorenz, I

    2015-01-01

    Acid-base abnormalities in neonatal diarrheic calves can be assessed by using the Henderson-Hasselbalch equation or the simplified strong ion approach which use the anion gap (AG) or the strong ion gap (SIG) to quantify the concentration of unmeasured strong anions such as D-lactate. To determine and compare the clinical utility of AG and SIG in quantifying the unmeasured strong anion charge in neonatal diarrheic calves, and to examine the associations between biochemical findings and acid-base variables by using the simplified strong ion approach. We hypothesized that the SIG provides a more accurate prediction of unmeasured strong anions than the AG. Eight hundred and six neonatal diarrheic calves admitted to a veterinary teaching hospital. Retrospective study utilizing clinicopathologic findings extracted from medical records. Hyperphosphatemia was an important predictor of venous blood pH. Serum inorganic phosphorus and plasma D-lactate concentrations accounted for 58% of the variation in venous blood pH and 77% of the variation in AG and SIG. Plasma D- and total lactate concentrations were slightly better correlated with SIG (rs = -0.69; -0.78) than to AG (rs = 0.63; 0.74). Strong ion gap is slightly better at quantifying the unmeasured strong anion concentration in neonatal diarrheic calves than AG. Phosphorus concentrations should be included as part of the calculation of Atot when applying the simplified strong ion approach to acid-base balance to critically ill animals with hyperphosphatemia. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  8. Bound anionic states of adenine

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-20

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

  9. Anion binding in biological systems

    Science.gov (United States)

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

    2009-11-01

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

  10. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-15

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

  11. Power Flow Calculation for Weakly Meshed Distribution Networks with Multiple DGs Based on Generalized Chain-table Storage Structure

    DEFF Research Database (Denmark)

    Chen, Shuheng; Hu, Weihao; Chen, Zhe

    2014-01-01

    Based on generalized chain-table storage structure (GCTSS), a novel power flow method is proposed, which can be used to solve the power flow of weakly meshed distribution networks with multiple distributed generators (DGs). GCTSS is designed based on chain-table technology and its target is to de......Based on generalized chain-table storage structure (GCTSS), a novel power flow method is proposed, which can be used to solve the power flow of weakly meshed distribution networks with multiple distributed generators (DGs). GCTSS is designed based on chain-table technology and its target...... is to describe the topology of radial distribution networks with a clear logic and a small memory size. The strategies of compensating the equivalent currents of break-point branches and the reactive power outputs of PV-type DGs are presented on the basis of superposition theorem. Their formulations...

  12. Effect of Cation on Physical Properties and CO2 Solubility for Phosphonium-Based Ionic Liquids with 2-Cyanopyrrolide Anions.

    Science.gov (United States)

    Seo, Samuel; DeSilva, M Aruni; Xia, Han; Brennecke, Joan F

    2015-09-03

    A series of tetraalkylphosphonium 2-cyanopyrrolide ([Pnnnn][2-CNPyr]) ionic liquids (ILs) were prepared to investigate the effect of cation size on physical properties and CO2 solubility. Each IL was synthesized in our laboratory and characterized by NMR spectroscopy. Their physical properties, including density, viscosity, and ionic conductivity, were determined as a function of temperature and fit to empirical equations. The density gradually increased with decreasing cation size, while the viscosity decreased noticeably. In addition, the [Pnnnn][2-CNPyr] ILs with large cations exhibited relatively low degrees of ionicity based on analysis of the Walden plots. This implies the presence of extensive ion pairing or formation of aggregates resulting from van der Waals interactions between the long hydrocarbon substituents. The CO2 solubility in each IL was measured at 22 °C using a volumetric method. While the anion is typically known to be predominantly responsible for the CO2 capture reaction, the [Pnnnn][2-CNPyr] ILs with shorter alkyl chains on the cations exhibited slightly stronger CO2 binding ability than the ILs with longer alkyl chains. We attribute this to the difference in entropy of reaction, as well as the variation in the relative degree of ionicity.

  13. An interference-free glucose biosensor based on an anionic redox polymer-mediated enzymatic oxidation of glucose.

    Science.gov (United States)

    Deng, Huimin; Shen, Wei; Gao, Zhiqiang

    2013-07-22

    Herein a novel strategy for the construction of an amperometric biosensor for highly sensitive and selective determination of glucose is described. The biosensor is made of a biocomposite membrane of glucose oxidase (GOx) and an Os(bpy)2 (bpy=2,2'-bipyridine)-based anionic redox polymer (Os-RP) mediator. The biosensor is fabricated through the co-immobilization of GOx and the Os-RP on the surface of a glassy carbon electrode by a simple one-step chemical crosslinking process. The crosslinked Os-RP/GOx composite membrane shows excellent catalytic activity toward the oxidation of glucose. Under optimal experimental conditions, a linear correlation between the oxidation current of glucose in amperometry at 0.25 V (vs. Ag/AgCl) and glucose concentration up to 10 mM with a sensitivity of 16.5 μA mM(-1) cm(-2) and a response time glucose in the presence of ascorbic acid and uric acid. The low hydrophobicity of the composite membrane also effectively retards the transport of molecular oxygen within the membrane. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Anion and cation effects on the size control of Au nanoparticles prepared by sputter deposition in imidazolium-based ionic liquids.

    Science.gov (United States)

    Hatakeyama, Yoshikiyo; Judai, Ken; Onishi, Kei; Takahashi, Satoshi; Kimura, Satoshi; Nishikawa, Keiko

    2016-01-28

    The sputter deposition of metals in an ionic liquid (IL) capture medium is a simple and elegant method for preparing nanoparticles without any chemical reaction. Although there have been some reports on the size determination factors for Au nanoparticles (AuNPs) prepared using this method, the effects with respect to the type of IL used have not been clearly elucidated. This is because there are some complicating factors, some of which have been revealed by our previous systematic studies. In the present study, we prepare AuNPs in nine types of imidazolium-based IL to examine the size determination effects of the type of anion involved, the length of the alkyl chain of the cation, and the preparation temperature for each IL, while keeping other factors constant. For most of the capture media ILs, the sizes of the AuNPs increase with an increase in temperature. The AuNPs prepared in ILs containing different types of anions exhibit distinctly different particle sizes and temperature dependences. Conversely, the alkyl chain is regarded as a secondary stabilizer that works only at higher preparation temperatures. We conclude that the sizes of AuNPs prepared by this method may be determined by the competition between the collision frequency of the ejected Au atoms and the stabilizing capability of the anions that form the first coordination shell around the AuNPs. The AuNP sizes are closely related to the volume of anions.

  15. External anion effect on the synthesis of new MOFs based on formate and a twisted divergent ligands

    Energy Technology Data Exchange (ETDEWEB)

    Lago, Ana Belén, E-mail: ablago@uvigo.es [Departamento de Química Inorgánica/Facultade de Química, Instituto de Investigación Biomédica (IBI), Universidade de Vigo, E-36310 Vigo, Galicia (Spain); Carballo, Rosa [Departamento de Química Inorgánica/Facultade de Química, Instituto de Investigación Biomédica (IBI), Universidade de Vigo, E-36310 Vigo, Galicia (Spain); Lezama, Luis [BCMaterials & Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Apartado 644, 48080 Bilbao (Spain); Vázquez-López, Ezequiel M. [Departamento de Química Inorgánica/Facultade de Química, Instituto de Investigación Biomédica (IBI), Universidade de Vigo, E-36310 Vigo, Galicia (Spain)

    2015-11-15

    New copper(II) metal–organic compounds with the formulae [Cu{sub 3}Cl(HCO{sub 2}){sub 5}(SCS){sub 3}(H{sub 2}O){sub 2}]·8H{sub 2}O·EtOH (1) and [Cu{sub 3}(HCO{sub 2}){sub 4}(SCS){sub 4}(H{sub 2}O){sub 2}](NO{sub 3}){sub 2}·9H{sub 2}O (2) (SCS=bis(4-pyridylthio)methane) have been synthesized after a careful study of the reaction of the SCS ligand with copper(II) formate. The compounds were obtained in the presence of sodium chloride and nitrate salts under microwave irradiation. The influence of the anion at different metal/anion ratios on the final architecture has been studied. The new chloride-MOF 1 has been characterized by electron paramagnetic resonance (EPR), magnetic properties and single crystal X-ray diffraction studies. The thermal stability and topological analysis have also been investigated. - Highlights: • Microwave synthesis of coordination polymers. • Anion-derived structural changes. • Influence of anions at different metal/anion ratios on the final architectures. • EPR and magnetic characterization of a MOF compound.

  16. Ditopic receptors based on lower- and upper-rim substituted hexahomotrioxacalix[3]arenes: cation-controlled hydrogen bonding of anion.

    Science.gov (United States)

    Ni, Xin-Long; Tahara, Jun; Rahman, Shofiur; Zeng, Xi; Hughes, David L; Redshaw, Carl; Yamato, Takehiko

    2012-03-05

    Heteroditopic hexahomotrioxacalix[3]arene receptors that are capable of binding an anion and a cation simultaneously in a cooperative fashion were synthesized. The structure of one of the triamide derivatives was confirmed by single-crystal X-ray diffraction. The binding of alkali metals at the lower rim, and the binding of anions (chloride, bromide) at the upper rim, has been investigated by using (1)H NMR titration experiments. Alkali metal binding at the lower rim controls the calix cavity. Li(+)-ion binding to the lower rim can improve the binding ability of anions at the upper rim amide moiety by a factor of 15, thus suggesting a strong positive allosteric effect for anion recognition. However, when a Na(+) cation is bound to the ionophoric site on the lower rim, the calix cavity is changed from a "flattened cone" to a more-upright form, which is favored for intramolecular hydrogen bonding between the neighboring NH and C=O groups; this change can block the inclusion of anions onto the amide moiety at the upper rim, which strongly suggests a negative allosteric effect of Na(+)-ion binding, which controls the cooperative recognition system. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Design and synthesis of a water-stable anionic uranium-based metal-organic framework (MOF) with ultra large pores

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peng; Vermeulen, Nicolaas A.; Gong, Xirui; Malliakas, Christos D.; Stoddart, J. Fraser; Hupp, Joseph T. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Farha, Omar K. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; King Abdulaziz Univ., Jeddah (Saudi Arabia). Dept. of Chemistry

    2016-08-22

    Ionic metal-organic frameworks (MOFs) are a subclass of porous materials that have the ability to incorporate different charged species in confined nanospace by ion-exchange. To date, however, very few examples combining mesoporosity and water stability have been realized in ionic MOF chemistry. Herein, we report the rational design and synthesis of a water-stable anionic mesoporous MOF based on uranium and featuring tbo-type topology. The resulting tbo MOF exhibits exceptionally large open cavities (3.9 nm) exceeding those of all known anionic MOFs. By supercritical CO{sub 2} activation, a record-high Brunauer-Emmett-Teller (BET) surface area (2100 m{sup 2} g{sup -1}) for actinide-based MOFs has been obtained. Most importantly, however, this new uranium-based MOF is water-stable and able to absorb positively charged ions selectively over negatively charged ones, enabling the efficient separation of organic dyes and biomolecules.

  18. Plasma-grafted alkaline anion-exchange membranes based on polyvinyl chloride for potential application in direct alcohol fuel cell

    Science.gov (United States)

    Hu, Jue; Zhang, Chengxu; Cong, Jie; Toyoda, Hirotaka; Nagatsu, Masaaki; Meng, Yuedong

    2011-05-01

    Plasma grafting is employed to prepare alkaline anion-exchange membranes in this study. The attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis demonstrate that the benzyltrimethylammonium cationic groups are successfully introduced into the polyvinyl chloride matrix via plasma grafting, quaternization and alkalization. The plasma-grafted alkaline anion-exchange membrane exhibits a satisfactory ionic exchange capacity (1.01 mmol g-1), thermal stability, mechanical property, ionic conductivity (0.0145 S cm-1) and methanol permeability (9.59 × 10-12 m2 s-1), suggesting a great potential for application in direct alcohol fuel cells. The open circuit voltage of air-breathing ADAFC using plasma-grafted alkaline anion-exchange membrane is 0.796 V with 1 M EtOH solution at ambient temperature.

  19. Splitting and acquiring quantum information with perfect W states based on weak cross-Kerr nonlinearities

    Science.gov (United States)

    Xiu, Xiao-Ming; Cui, Cen; Lin, Yan-Fang; Dong, Li; Dong, Hai-Kuan; Gao, Ya-Jun

    2018-01-01

    With the assistance of weak cross-Kerr nonlinear interaction between photons and coherent states via Kerr media, we propose a scheme to split and acquire quantum information with three-photon perfect W states. By means of a fault-tolerant circuit, the perfect W states are distributed to the participants without being affected by the collective noise. And on this basis we present a scheme for splitting and acquiring a single-photon state with the shared perfect W states. Together with the mature techniques of classical feed-forward, simple and available linear optical elements are applied in the procedure, afford enhancing the feasibility of the theoretical scheme proposed here.

  20. Beamstop-based low-background ptychography to image weakly scattering objects

    DEFF Research Database (Denmark)

    Reinhardt, Juliane; Hoppe, Robert; Hofmann, Georg

    2017-01-01

    of the complementary information contained in the two scans. We experimentally demonstrate the potential of this scheme for hard X-ray ptychography by imaging a weakly scattering object composed of catalytic nanoparticles and provide the analysis of the signal-to-background ratio in the diffraction patterns......., which improve the experimental setup in terms of background reduction or better coverage of high dynamic range in the diffraction patterns. Here, we discuss an alternative approach: we combine two ptychographic scans with and without beamstop and reconstruct them simultaneously taking advantage...

  1. Multi-criteria decision making development of ion chromatographic method for determination of inorganic anions in oilfield waters based on artificial neural networks retention model.

    Science.gov (United States)

    Stefanović, Stefica Cerjan; Bolanča, Tomislav; Luša, Melita; Ukić, Sime; Rogošić, Marko

    2012-02-24

    This paper describes the development of ad hoc methodology for determination of inorganic anions in oilfield water, since their composition often significantly differs from the average (concentration of components and/or matrix). Therefore, fast and reliable method development has to be performed in order to ensure the monitoring of desired properties under new conditions. The method development was based on computer assisted multi-criteria decision making strategy. The used criteria were: maximal value of objective functions used, maximal robustness of the separation method, minimal analysis time, and maximal retention distance between two nearest components. Artificial neural networks were used for modeling of anion retention. The reliability of developed method was extensively tested by the validation of performance characteristics. Based on validation results, the developed method shows satisfactory performance characteristics, proving the successful application of computer assisted methodology in the described case study. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Preparation of room temperature ionic liquids based on aliphatic onium cations and asymmetric amide anions and their electrochemical properties as a lithium battery electrolyte

    Science.gov (United States)

    Matsumoto, Hajime; Sakaebe, Hikari; Tatsumi, Kuniaki

    The physical and electrochemical properties of room temperature ionic liquids (RTILs) based on asymmetric amide anions (TSAC: 2,2,2-trifluoro- N-(trifluoromethylsulfonyl)acetamide, C1C2: N-(trifluoromethylsulfonyl)pentafluoroethylsulfonamide) and aliphatic onium cations, such as ammonium, phosphonium, and sulfonium, were reported. The melting point of the C1C2 salts decreased compared to the corresponding TFSI salts (TFSI: bis(trifluoromethylsulfonyl)imide), however, the viscosity was about twice that of the TFSI salts. Relatively low viscosity RTILs based on aliphatic onium cations could be prepared using the TSAC anion and tetraalkylammonium cation containing an alkoxy group. The linear sweep voltammogram of these RTILs with and without Li-TFSI were investigated in order to estimate the electrochemical windows and possible use as a lithium battery electrolyte.

  3. Polyelectrolytes with sterically hindered anionic charges

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, T.F.; Liu, H.; Okamoto, Y.; Lee, H.S.; Skotheim, T.A. (Polytechnic Inst. of Brooklyn, NY (USA); Brookhaven National Lab., Upton, NY (USA))

    1989-01-01

    The central problem in the development of single phase polymer electrolytes with exclusive cation conduction has been inadequate ion mobility due to extensive ion pairing between the mobile cation and the covalently attached anion. We have developed a new class of single ion conducting polymers, or polyelectrolytes, based on highly flexible polysiloxane backbones and attached sterically hindered phenolate anions. The combination of a highly delocalized and sterically enclosed anionic charged separation and consequently enhanced cation mobility. 10 refs., 2 figs.

  4. Influence of cation structure on binary liquid-liquid equilibria for systems containing ionic liquids based on trifluoromethanesulfonate anion with hydrocarbons.

    Science.gov (United States)

    Marciniak, Andrzej; Karczemna, Ewa

    2010-04-29

    Binary liquid-liquid equilibria for 15 systems containing an ionic liquid (1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate) with a hydrocarbon (n-hexane, n-heptane, cyclohexane, benzene, toluene) were measured by the dynamic method. The influence of cation structure of trifluoromethanesulfonate anion based ionic liquids on solubility of aliphatic and aromatic hydrocarbons is discussed.

  5. Beamstop-based low-background ptychography to image weakly scattering objects.

    Science.gov (United States)

    Reinhardt, Juliane; Hoppe, Robert; Hofmann, Georg; Damsgaard, Christian D; Patommel, Jens; Baumbach, Christoph; Baier, Sina; Rochet, Amélie; Grunwaldt, Jan-Dierk; Falkenberg, Gerald; Schroer, Christian G

    2017-02-01

    In recent years, X-ray ptychography has been established as a valuable tool for high-resolution imaging. Nevertheless, the spatial resolution and sensitivity in coherent diffraction imaging are limited by the signal that is detected over noise and over background scattering. Especially, coherent imaging of weakly scattering specimens suffers from incoherent background that is generated by the interaction of the central beam with matter along its propagation path in particular close to and inside of the detector. Common countermeasures entail evacuated flight tubes or detector-side beamstops, which improve the experimental setup in terms of background reduction or better coverage of high dynamic range in the diffraction patterns. Here, we discuss an alternative approach: we combine two ptychographic scans with and without beamstop and reconstruct them simultaneously taking advantage of the complementary information contained in the two scans. We experimentally demonstrate the potential of this scheme for hard X-ray ptychography by imaging a weakly scattering object composed of catalytic nanoparticles and provide the analysis of the signal-to-background ratio in the diffraction patterns. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Time-dependent Anion Chemistry in the CSE IRC+10216

    Science.gov (United States)

    Guelin, M.; Agundez, M.; Cernicharo, J.; Gottlieb, C.; McCarthy, M.; Thaddeus, P.

    2011-05-01

    Following the spectral characterization of C-chain anions, in the Harvard microwave laboratory, we have discovered 6 anions in the envelope of the C-rich star IRC+10216 and set limits to the abundance of two others. The anions we studied in this source range from CCH- to C8H- and from CN- to C5N- [1,2,3]. Anion abundances are low and the rotational lines weak, even in favorable cases. Two years ago, we have been able to map C6H- in IRC+10216, with the PdB interferometer, and to show that it is located, like the C6H radical, in a hollow shell. The angular resolution of the observations (5) and the S/N ratio were however insufficient to spatially differentiate the anion from the radical. Taking advantage of the recent installation of a wide-band correlator on PdBI, we have re-observed with a twice higher resolution the 83 GHz line of C6H- , as well as nearby lines of C5N-, C4H-, C2H- and of several C-chain molecules and radicals. Except for CCH-, all those species are detected and we are currently analyzing their distributions and abundances. Chemistry models, based on the electron radiative attachment theory developed by Herbst and collaborators, predict that anions and parent radicals peak at different radii in the expanding CSE[4]. Predicted radial shifts range from a few arcsec, for C6H-, to more than 10 (500 yr) for C4H- and CN-. We know, from previous single-dish observations, that the actual abundances of C4H- and CN- , relative to C4H and CN, differ by orders of magnitude from radiative attachment model predictions, while those of the long anions, C6H- and C8H agree well with predictions. The new interferometric observations, allied to single-dish data, allow us to measure the formation/destruction time of the different species and to set constraints on the rates of electron radiative attachment, rates which, so far, are only crudely evaluated through the statistical theory. The relatively high abundances of CN-, C3N - and C5N - , compared to CCH-, C4H - and

  7. Simplified production and concentration of HIV-1-based lentiviral vectors using HYPERFlask vessels and anion exchange membrane chromatography

    Science.gov (United States)

    Kutner, Robert H; Puthli, Sharon; Marino, Michael P; Reiser, Jakob

    2009-01-01

    Background During the past twelve years, lentiviral (LV) vectors have emerged as valuable tools for transgene delivery because of their ability to transduce nondividing cells and their capacity to sustain long-term transgene expression in target cells in vitro and in vivo. However, despite significant progress, the production and concentration of high-titer, high-quality LV vector stocks is still cumbersome and costly. Methods Here we present a simplified protocol for LV vector production on a laboratory scale using HYPERFlask vessels. HYPERFlask vessels are high-yield, high-performance flasks that utilize a multilayered gas permeable growth surface for efficient gas exchange, allowing convenient production of high-titer LV vectors. For subsequent concentration of LV vector stocks produced in this way, we describe a facile protocol involving Mustang Q anion exchange membrane chromatography. Results Our results show that unconcentrated LV vector stocks with titers in excess of 108 transduction units (TU) per ml were obtained using HYPERFlasks and that these titers were higher than those produced in parallel using regular 150-cm2 tissue culture dishes. We also show that up to 500 ml of an unconcentrated LV vector stock prepared using a HYPERFlask vessel could be concentrated using a single Mustang Q Acrodisc with a membrane volume of 0.18 ml. Up to 5.3 × 1010 TU were recovered from a single HYPERFlask vessel. Conclusion The protocol described here is easy to implement and should facilitate high-titer LV vector production for preclinical studies in animal models without the need for multiple tissue culture dishes and ultracentrifugation-based concentration protocols. PMID:19220915

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

    Science.gov (United States)

    Wang, Haopeng; Jae Ko, Yeon; Zhang, Xinxing; Gantefoer, Gerd; Schnoeckel, Hansgeorg; Eichhorn, Bryan W.; Jena, Puru; Kiran, Boggavarapu; Kandalam, Anil K.; Bowen, Kit H.

    2014-03-01

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have investigated the extent to which the aluminum moieties within selected magnesium-aluminum clusters are Zintl anions. Magnesium-aluminum cluster anions were generated in a pulsed arc discharge source. After mass selection, photoelectron spectra of MgmAln- (m, n = 1,6; 2,5; 2,12; and 3,11) were measured by a magnetic bottle, electron energy analyzer. Calculations on these four stoichiometries provided geometric structures and full charge analyses for the cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra). Calculations revealed that, unlike the cases of recently reported sodium-aluminum clusters, the formation of aluminum Zintl anion moieties within magnesium-aluminum clusters was limited in most cases by weak charge transfer between the magnesium atoms and their aluminum cluster moieties. Only in cases of high magnesium content, e.g., in Mg3Al11 and Mg2Al12-, did the aluminum moieties exhibit Zintl anion-like characteristics.

  9. Systematic Reviews and Meta-Analyses - Literature-based Recommendations for Evaluating Strengths, Weaknesses, and Clinical Value.

    Science.gov (United States)

    Beitz, Janice M; Bolton, Laura L

    2015-11-01

    Good quality systematic reviews (SRs) summarizing best available evidence can help inform clinical decisions, improv- ing patient and wound outcomes. Weak SRs can misinform readers, undermining care decisions and evidence-based practice. To examine the strengths and weaknesses of SRs and meta-analyses and the role of SRs in contemporary evidence-based wound care practice, and using the search terms systematic review, meta-analysis, and evidence-based practice, the authors searched Medline and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) for important terminology and recommendations to help clinicians evaluate SRs with meta-analysis. Reputable websites, recent textbooks, and synthesized available literature also were reviewed to describe and summarize SR strengths and weaknesses. After developing a checklist for critically evaluating SR objectives, inclusion/exclusion criteria, study quality, data extraction and synthesis methods, meta-analysis homogeneity, accuracy of results, interpretation, and consistency between significant findings and abstract or conclusions, the checklist was applied to topical wound care SRs identified in Cochrane and MEDLINE searches. Best available evidence included in the SRs from 169 randomized controlled trials on 11,571 patients supporting topical intervention healing effects on burns, surgical sites, and diabetic, venous, or pressure ulcers was summarized and showed SRs and clinical trials can demonstrate different outcomes because the information/data are compiled differently. The results illustrate how evidence insufficient to support firm conclusions may still meet immediate needs to guide carefully considered clinical wound and patient care decisions while encouraging better future science.

  10. Anion exchange membrane

    Science.gov (United States)

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

    2013-05-07

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

  11. Novel Anion Exchange Resin-based Catalyst for Liquid-phase Methanol Synthesis at 373–393 K

    National Research Council Canada - National Science Library

    Aika, Ken-ichi; Kobayashi, Hidenobu; Harada, Kenji; Inazu, Koji

    2004-01-01

    A thermo-stable anion exchange resin–Raney Cu system was found as the most effective solid catalyst for low-temperature liquid-phase methanol synthesis at 373 to 393 K under 5.0 MPa of syngas (2H2/CO). With the catalyst...

  12. Dietary cation-anion difference effects on performance and acid-base status of dairy cows postpartum.

    Science.gov (United States)

    Hu, W; Murphy, M R; Constable, P D; Block, E

    2007-07-01

    Our objective was to examine the effect of dietary cation-anion difference (DCAD) on performance and acid-base status of cows postpartum. Sixteen Holstein and 8 Jersey multiparous cows were used immediately after calving to compare 2 DCAD [22 or 47 milliequivalents (Na + K - Cl - S)/100 g of dry matter (DM)] in a completely randomized design. The corn silage-based diets were formulated to contain 19.0% crude protein, 25.4% neutral detergent fiber, 15.0% acid detergent fiber, and 1.69 Mcal of net energy for lactation per kilogram (on a DM basis). An additional 2.3 kg of alfalfa hay was fed during the first 5 d postpartum, and then milk, blood, and urine samples were collected weekly for 6 wk. Repeated-measures (with an extra between-cow effect) mixed model analysis indicated that DCAD did not affect DM intake (18.2 and 18.3 kg/d), milk production (33.5 and 33.3 kg/d), milk composition (3.96 and 4.11% fat, 3.11 and 3.00% protein, and 8.95 and 8.83% solids-not-fat), jugular venous blood pH (7.395 and 7.400), HCO3(-) concentration (27.3 and 27.6 mEq/L), or partial pressure of CO2 (46.7 and 46.5 mmHg). Elevated coccygeal venous plasma branched-chain AA (431 and 558 microM) and ratio of essential AA to total AA (0.390 and 0.434) in cows with DCAD of 22 vs. 47 mEq/100 g of DM indicated that N metabolism in the rumen was affected, probably resulting in more microbial protein flowing to the small intestine. Urinary pH tended to increase with DCAD (8.12 vs. 8.20). Higher net acid excretion in cows with DCAD of 22 vs. 47 mEq/100 g of DM (-24 and -41 mM:mM) suggested that net acid excretion was much more indicative of acid load than blood acid-base parameters in cows postpartum. Intake of DM and performance of cows postpartum were not improved when DCAD increased from 22 to 47 mEq/100 g of DM, likely because cows immediately after calving respond more variably to dietary treatments and that makes treatment effects difficult to detect.

  13. Weak antilocalization in a three-dimensional topological insulator based on a high-mobility HgTe film

    Science.gov (United States)

    Savchenko, M. L.; Kozlov, D. A.; Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A.

    2016-09-01

    The anomalous magnetoresistance (AMR) caused by the weak antilocalization effects in a three-dimensional topological insulator based on a strained mercury telluride film is experimentally studied. It is demonstrated that the obtained results are in a good agreement with the universal theory of Zduniak, Dyakonov, and Knap. It is found that the AMR in the bulk band gap is far below that expected for the system of Dirac fermions. Such a discrepancy can assumingly be related to a nonzero effective mass of Dirac fermions. The filling of energy bands in the bulk is accompanied by a pronounced increase in the AMR. This is a signature of the weak coupling between the surface and bulk charge carriers.

  14. Selective recognition of sulfate anions in a 95% ethanol solvent with a simple neutral salicylaldehyde dansyl hydrazine Schiff base tuned by Brønsted-Lowry acid-base reaction.

    Science.gov (United States)

    Wei, Gao-Ning; Zhang, Jing-Li; Jia, Cang; Fan, Wei-Zhen; Lin, Li-Rong

    2014-07-15

    A new Schiff base compound, 5-(dimethylamino)-N'-(2-hydroxybenzylidene)naphthalene-1-sulfonohydrazide (R), has been synthesized, characterized, and employed as a selective fluorescence receptor for the recognition of sulfate anions. UV-vis absorption, fluorescence emission, (1)H NMR spectra and DFT calculation studies on the system have been carried out to determine the nature of the interactions between R and anions. The results reveal that the deprotonation of the phenol without the need of a strong base leads to the formation of a hydrogen-bonding complex with a -SO2-NH- group, which is responsible for the spectra changes. The deprotonation process for the selectivity recognition of sulfate can be tuned by the Brønsted-Lowry acid-base reaction in nonaqueous solutions, revealing that suitable phenolic hydroxyl acidity is the key factor for anion recognition selectivity. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2014-05-28

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

  16. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-08

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

  17. Exploiting Attribute Correlations: A Novel Trace Lasso-Based Weakly Supervised Dictionary Learning Method.

    Science.gov (United States)

    Wu, Lin; Wang, Yang; Pan, Shirui

    2017-12-01

    It is now well established that sparse representation models are working effectively for many visual recognition tasks, and have pushed forward the success of dictionary learning therein. Recent studies over dictionary learning focus on learning discriminative atoms instead of purely reconstructive ones. However, the existence of intraclass diversities (i.e., data objects within the same category but exhibit large visual dissimilarities), and interclass similarities (i.e., data objects from distinct classes but share much visual similarities), makes it challenging to learn effective recognition models. To this end, a large number of labeled data objects are required to learn models which can effectively characterize these subtle differences. However, labeled data objects are always limited to access, committing it difficult to learn a monolithic dictionary that can be discriminative enough. To address the above limitations, in this paper, we propose a weakly-supervised dictionary learning method to automatically learn a discriminative dictionary by fully exploiting visual attribute correlations rather than label priors. In particular, the intrinsic attribute correlations are deployed as a critical cue to guide the process of object categorization, and then a set of subdictionaries are jointly learned with respect to each category. The resulting dictionary is highly discriminative and leads to intraclass diversity aware sparse representations. Extensive experiments on image classification and object recognition are conducted to show the effectiveness of our approach.

  18. Theory and method for weak signal detection in engineering practice based on stochastic resonance

    Science.gov (United States)

    Zhao, Wenli; Wang, Linze; Fan, Jian

    2017-11-01

    In this paper, the Kramers rate was derived using the Fokker-Planck (FP) equation with the condition of adiabatic approximation (the amplitude and frequency of signal detected are small ≪ 1) and the signal-to-noise ratio (SNR) was proved by means of Fourier transform and the power spectrum in bistable system. This is a concise and superior method to demonstrate the Kramers rate and SNR compared to the past methods. It is convenient for readers to understand. The SNR of the bistable system obtained shows that stochastic resonance (SR) can be used to realize energy transition from noise to a periodic signal under the adiabatic approximation condition. Therefore, SR could enhance the SNR of the output signal. The signal modulation technique was employed to transform the large frequency components into a small parameter signal to meet the adiabatic approximation requirement. Furthermore, we have designed the model of modulator. The simulation results show that the modulation method can generate SR in a bistable system and detect weak signals with large parameters from strong noise background.

  19. Influence of acetazolamide loading on the (in vitro) performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions.

    Science.gov (United States)

    Tamilvanan, Shunmugaperumal; Kumar, Balakrishnan Ajith

    2011-09-01

    Acetazolamide (ACZM)-loaded anionic, cationic, and neutral-charged oil-in-water nanosized emulsions were prepared and compared with their mean droplet diameter, surface charge, entrapment efficiency, freeze-thaw cycling stability, in vitro drug release, and transcorneal permeation. The present study aims to determine the influence of ACZM loading on the performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions. Regardless of charges, all of these emulsions exhibited a nanometer range mean particle diameter (240-443 nm) following autoclave sterilization. While the anionic and cationic emulsions did show high negative (-36.9 mV) and positive zeta potential (+41.4 mV) values, the neutral-charged emulsion did not. Presence of cryoprotectants (5% w/w sucrose + 5% w/w sorbitol) improved the stability of cationic emulsion to droplet aggregation during freeze-thaw cycling. The in vitro release kinetic behavior of drug exchange with physiological anions present in the simulated tear solution appears to be complex and difficult to characterize using mathematical fitting model equations. Augmentation in drug permeation through goat cornea, in vitro, was noticed for cationic emulsion. ACZM-loaded cationic nanosized emulsion could be suitable for topical application into eye to elicit better therapeutic effect in comparison with its anionic and neutral-charged emulsions.

  20. Effect of anionic salts in concentrate mixture and calcium intake on some blood and urine minerals, acid-base balance and feed intake of dry pregnant cows on grass silage based feeding

    Directory of Open Access Journals (Sweden)

    S. TAURIAINEN

    2008-12-01

    Full Text Available Twelve Ayrshire and eight Friesian cows were randomly assigned to one of four prepartum diets in a 2 x 2 factorially designed experiment to determine the effect of anionic diet and calcium (Ca intake on Ca metabolism, acid-base status and feed intake of grass silage based diets during the dry period. Four diets provided either 34 g or 74 g total dietary Ca/day, and were either anionic or cationic. Dietary cation-anion balance (DCAB, calculated as milliequivalents [(Na+ + K+ - (Cl- + S2-], was -247 mEq/kg dry matter (DM in the low DCAB group and +34 mEq/kg DM in the high DCAB group. DCAB was formulated using NH4Cl, (NH42SO4 and MgCl2 as anionic salts. Cows received grass silage (5.2 kg DM, hay (0.9 kg DM and concentrate mixture (1.6 kg DM until calving. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, the day after calving and 1 week following calving. The results indicate that the reduction of cation-anion balance induced mild metabolic acidosis and increased the ability of the cow to maintain blood Ca concentration. However, DCAB should be higher since urinary pH decreased markedly (< 6 and so remarkable changes in some blood electrolyte concentrations were noticed.;

  1. The AHA Moment: Assessment of the Redox Stability of Ionic Liquids Based on Aromatic Heterocyclic Anions (AHAs) for Nuclear Separations and Electric Energy Storage.

    Science.gov (United States)

    Shkrob, Ilya A; Marin, Timothy W

    2015-11-19

    Because of their extended conjugated bond network, aromatic compounds generally have higher redox stability than less saturated compounds. We conjectured that ionic liquids (ILs) consisting of aromatic heterocyclic anions (AHAs) may exhibit improved radiation and electrochemical stability. Such properties are important in applications of these ILs as diluents in radionuclide separations and electrolytes in the electric energy storage devices. In this study, we systematically examine the redox chemistry of the AHAs. Three classes of these anions have been studied: (i) simple 5-atom ring AHAs, such as the pyrazolide and triazolides, (ii) AHAs containing an adjacent benzene ring, and (iii) AHAs containing electron-withdrawing groups that were introduced to reduce their basicity and interaction with metal ions. It is shown that fragmentation in the reduced and oxidized states of these AHAs does not generally occur, and the two main products, respectively, are the H atom adduct and the imidyl radical. The latter species occurs either as an N σ-radical or as an N π-radical, depending on the length of the N-N bond, and the state that is stabilized in the solid matrix is frequently different from that having the lowest energy in the gas phase. In some instances, the formation of the sandwich π-stack dimer radical anions has been observed. For trifluoromethylated anions, H adduct formation did not occur; instead, there was facile loss of fluoride from their fluorinated groups. The latter can be problematic in nuclear separations, but beneficial in batteries. Overall, our study suggests that AHA-based ILs are viable candidates for use as radiation-exposed diluents and electrolytes.

  2. Preparation of Two-Layer Anion-Exchange Poly(ethersulfone Based Membrane: Effect of Surface Modification

    Directory of Open Access Journals (Sweden)

    Lucie Zarybnicka

    2016-01-01

    Full Text Available The present work deals with the surface modification of a commercial microfiltration poly(ethersulfone membrane by graft polymerization technique. Poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride surface layer was covalently attached onto the poly(ethersulfone support layer to improve the membrane electrochemical properties. Followed by amination, a two-layer anion-exchange membrane was prepared. The effect of surface layer treatment using the extraction in various solvents on membrane morphological and electrochemical characteristics was studied. The membranes were tested from the point of view of water content, ion-exchange capacity, specific resistance, permselectivity, FT-IR spectroscopy, and SEM analysis. It was found that the two-layer anion-exchange membranes after the extraction using tetrahydrofuran or toluene exhibited smooth and porous surface layer, which resulted in improved ion-exchange capacity, electrical resistance, and permselectivity of the membranes.

  3. Combined study of anion recognition by a carbazole-based neutral tripodal receptor in a competitive environment.

    Science.gov (United States)

    Curiel, David; Sánchez, Guzmán; Ramírez de Arellano, Carmen; Tárraga, Alberto; Molina, Pedro

    2012-03-07

    Anion recognition studies have been carried out on a series of neutral synthetic receptors in which carbazole-2-carboxamide has been used as building block. Different ligands which include one to three carbazole units in their structure have been prepared. Binding experiments have been performed under competitive conditions in DMSO and DMSO-water solutions. The tripodal receptor offered a better host-guest association due to the synergistic effect of a well arranged set of hydrogen bonds. A selective response towards the biologically important pyrophosphate anion has been achieved. This selectivity is enhanced when studies are carried out with an increasing water content, which gets as high as 20% (v/v) in NMR experiments. The significance of this result lies in the use of a neutral receptor which exclusively interacts with the anionic guest through hydrogen bonding. The influence of multiple equilibria in the studied system has been analysed. Several techniques ((1)H NMR, (31)P NMR, mass spectrometry, diffusion-NMR, ITC, absorption and emission spectroscopy) have been employed to get a better understanding of the different processes taking place in solution for the evaluated receptors.

  4. Bright mono-aqua europium complexes based on triazacyclononane that bind anions reversibly and permeate cells efficiently.

    Science.gov (United States)

    Butler, Stephen J; McMahon, Brian K; Pal, Robert; Parker, David; Walton, James W

    2013-07-15

    A series of five europium(III) complexes has been prepared from heptadentate N5O2 ligands that possess a brightness of more than 10 mM(-1) cm(-1) in water, following excitation over the range λ=330-355 nm. Binding of several oxy anions has been assessed by emission spectral titrimetric analysis, with the binding of simple carboxylates, lactate and citrate involving a common ligation mode following displacement of the coordinated water. Selectivity for bicarbonate allows the rapid determination of this anion in human serum, with K(d)=37 mM (295 K). The complexes are internalised quickly into mammalian cells and exhibit a mitochondrial localisation at early time points, migrating after a few hours to reveal a predominant lysosomal distribution. Herein, we report the synthesis and complexation behaviour of strongly emissive europium (III) complexes that bind oxy-anions in aqueous media with an affinity and selectivity profile that is distinctively different from previously studied systems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Multi-bearing weak defect detection for wayside acoustic diagnosis based on a time-varying spatial filtering rearrangement

    Science.gov (United States)

    Zhang, Shangbin; He, Qingbo; Ouyang, Kesai; Xiong, Wei

    2018-02-01

    The wayside Acoustic Defective Bearing Detector (ADBD) system plays an important role in ensuring the safety of railway transportation. However, Doppler distortion and multi-bearing source aliasing in the acquired acoustic bearing signals significantly decrease the accuracy of bearing diagnosis. Traditional multisource separation schemes using time-frequency filters constructed by a single microphone signal always show poor performance on weak signal separation. Inspired by an assumption that the spatial location of different sources is different, this paper proposes a novel time-varying spatial filtering rearrangement (TSFR) scheme based on a microphone array to overcome current difficulties. In the scheme, a zero-angle spatial filter and peak searching are proposed to obtain the time-centers of corresponding sources. Based on these time-centers, several time-varying spatial filters are designed to extract different source signals. Then interpolation and rearrangement are used to correct the Doppler distortion and reconstruct the corresponding separated signals. Finally, the train bearing fault diagnosis is implemented by analyzing the envelope spectrum of the corrected signals. Because the time-varying spatial filter construction is only dependent on the source location and has little relationship with the signal energy, the proposed TSFR scheme has significant advantages in weak signal separation and diagnosis in comparison with traditional ones. With the verifications by both simulation and experiment cases, the proposed array-based TSFR scheme shows a good performance on multiple fault source separation and is expected to be used in the ADBD system.

  6. Two Types of Anion-Induced Reconstruction of Schiff-Base Macrocyclic Zinc Complexes: Ring-Contraction and Self-Assembly of a Molecular Box.

    Science.gov (United States)

    Zhang, Kun; Zhang, Lei; Feng, Gen-Feng; Hu, Yong; Chang, Fei-Fan; Huang, Wei

    2016-01-04

    Two 46-membered [2 + 2] Schiff-base macrocyclic dinuclear Zn(II) complexes (1a and 1b) were investigated deeply by the postmodification strategy, and two types of supramolecular processes (ring-contraction and self-assembly) have been achieved after the addition of specific anions as stimulus for the equilibrium of Schiff-base macrocyclic complexes. Namely, in the presence of linear three-atom SCN(-), 1a was degraded into two 23-membered [1 + 1] Schiff-base macrocyclic complexes simultaneously (mononuclear Zn(II) complex 2 and dinuclear Zn(II) complex 3). In contrast, 1b was only transformed into the macrocyclic mononuclear complex 5. More interestingly, in the case of pseudolinear five-atom N(CN)2(-), supramolecular self-assembly took place instead of the above-mentioned ring-contraction. Finally, 1a was assembled into a unique molecular box 4 with two 46-membered [2 + 2] Schiff-base macrocyclic heteronuclear Zn4Na4 substrates and double μ2-N(CN)2(-) bridges, while no similar assembly process was observed for 1b. The geometry of anions and pH values slightly adjusted by the pendant arms on the macrocyclic skeletons are believed to be the critical factors for the different supramolecular processes originating from the dynamic covalent chemistry of Schiff-base imine bonds.

  7. Influence of Weak Base Addition to Hole-Collecting Buffer Layers in Polymer:Fullerene Solar Cells

    Directory of Open Access Journals (Sweden)

    Jooyeok Seo

    2017-02-01

    Full Text Available We report the effect of weak base addition to acidic polymer hole-collecting layers in normal-type polymer:fullerene solar cells. Varying amounts of the weak base aniline (AN were added to solutions of poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS. The acidity of the aniline-added PEDOT:PSS solutions gradually decreased from pH = 1.74 (AN = 0 mol% to pH = 4.24 (AN = 1.8 mol %. The electrical conductivity of the PEDOT:PSS-AN films did not change much with the pH value, while the ratio of conductivity between out-of-plane and in-plane directions was dependent on the pH of solutions. The highest power conversion efficiency (PCE was obtained at pH = 2.52, even though all devices with the PEDOT:PSS-AN layers exhibited better PCE than those with the pristine PEDOT:PSS layers. Atomic force microscopy investigation revealed that the size of PEDOT:PSS domains became smaller as the pH increased. The stability test for 100 h illumination under one sun condition disclosed that the PCE decay was relatively slower for the devices with the PEDOT:PSS-AN layers than for those with pristine PEDOT:PSS layers.

  8. Three Highly Stable Cobalt MOFs Based on "Y"-Shaped Carboxylic Acid: Synthesis and Absorption of Anionic Dyes.

    Science.gov (United States)

    Yan, Wei; Han, Li-Juan; Jia, Hai-Lang; Shen, Kang; Wang, Ting; Zheng, He-Gen

    2016-09-06

    Three Co(II) metal-organic frameworks (MOFs) were synthesized employing a rational design approach. On the basis of the different structures of three complexes, we tested their absorption properties toward two anionic dyes. The absorption results indicate that not only uncoordinated functional groups in the structure play an important role in adsorbing capacity but also physical forces can affect absorbing ability. Water stability testing shows that three crystals display high stability in aqueous solutions with different pH values. To our delight, the framework integrity of three complexes can be well-retained even after absorbing dyes.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Marija Kirchhöfer

    2014-08-01

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

  11. Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

    Directory of Open Access Journals (Sweden)

    Jin-Feng Li

    2015-06-01

    Full Text Available The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M2(CN5]−1 (M =  Ca, Be clusters. At CCSD(T level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE. The largest one is 9.70 eV for [Ca2(CN5]−1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T, outer valence Green’s function (OVGF method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties.

  12. Strengths and Weaknesses in a Human Rights-Based Approach to International Development

    DEFF Research Database (Denmark)

    Broberg, Morten; Sano, Hans-Otto

    2017-01-01

    , the approach is related to the processes of empowerment, forms of advocacy, and the use of legal instruments in defence of groups of people who are poor, discriminated against or marginalised. We conclude that a human rights based approach provides new avenues for providing help to vulnerable groups...

  13. Strengths and Weaknesses in a Human Rights-Based Approach to International Development

    DEFF Research Database (Denmark)

    Broberg, Morten; Sano, Hans-Otto

    2017-01-01

    The human rights based approach to development cooperation has found recent support from both development cooperation actors and NGOs active in developing countries. We set out to define this approach, how it is applied, and to identify its central agents and principal components. Through examples...

  14. Strengths and Weaknesses in a Human Rights-Based Approach to International Development

    DEFF Research Database (Denmark)

    Broberg, Morten; Sano, Hans-Otto

    2018-01-01

    The human rights based approach to development cooperation has found recent support from both development cooperation actors and NGOs active in developing countries. We set out to define this approach, how it is applied, and to identify its central agents and principal components. Through examples......, the approach is related to the processes of empowerment, forms of advocacy, and the use of legal instruments in defence of groups of people who are poor, discriminated against or marginalised. We conclude that a human rights based approach provides new avenues for providing help to vulnerable groups...... we show how the approach works in practice, and we identify and discuss three human rights principles that play particularly important roles in its implementation: (i) participation and inclusion, (ii) non-discrimination and equality, and (iii) accountability. We show that in terms of implementation...

  15. NMR-Based Strategies to Elucidate Bioactive Conformations of Weakly Binding Ligands

    Science.gov (United States)

    Blommers, Marcel J. J.; Strauss, Andre; Geiser, Martin; Ramage, Paul; Sparrer, Helmut; Jahnke, Wolfgang

    Key processes in molecular biology are regulated by interactions between biomolecules. Protein-protein and protein-ligand interactions, e.g., in signal transduction pathways, rely on the subtle interactions between atoms at the binding interface of the involved molecules. Because biomolecules often have many interacting partners, these interactions are not necessarily strong. The study of molecular recognition gives insight into the complex network of signaling in life and is the basis of structure-based drug design.

  16. Fast high-throughput method for the determination of acidity constants by capillary electrophoresis: I. Monoprotic weak acids and bases.

    Science.gov (United States)

    Fuguet, Elisabet; Ràfols, Clara; Bosch, Elisabeth; Rosés, Martí

    2009-04-24

    A new and fast method to determine acidity constants of monoprotic weak acids and bases by capillary zone electrophoresis based on the use of an internal standard (compound of similar nature and acidity constant as the analyte) has been developed. This method requires only two electrophoretic runs for the determination of an acidity constant: a first one at a pH where both analyte and internal standard are totally ionized, and a second one at another pH where both are partially ionized. Furthermore, the method is not pH dependent, so an accurate measure of the pH of the buffer solutions is not needed. The acidity constants of several phenols and amines have been measured using internal standards of known pK(a), obtaining a mean deviation of 0.05 pH units compared to the literature values.

  17. All-fiber-based selective mode multiplexer and demultiplexer for weakly-coupled mode-division multiplexed systems

    Science.gov (United States)

    Igarashi, Koji; Park, Kyung Jun; Tsuritani, Takahiro; Morita, Itsuro; Kim, Byoung Yoon

    2018-02-01

    We show all-fiber-based selective mode multiplexers and demultiplexers for weakly-coupled mode-division multiplexed systems. We fabricate a set of six-mode multiplexer and demultiplexer based on fiber mode selective couplers, and experimentally evaluate the performance for the six-mode dual-polarization (DP) quadrature phase shift keying (QPSK) optical signals. In the mode multiplexer and demultiplexer, the mode couplings between the lower three modes and the higher three modes are suppressed to be less than -20 dB, which enables us to apply partial 6 ×6 MIMO equalizers even for the six-mode demultiplexing. For the six-mode DP-QPSK signals, the penalty of optical signal-to-noise ratio by replacing the full 12 ×12MIMO to the partial 6 ×6 MIMO is suppressed by less than 1 dB.

  18. Design of Multichannel Osmium-Based Metalloreceptor for Anions and Cations by Taking Profit from Metal-Ligand Interaction and Construction of Molecular Keypad Lock and Memory Device.

    Science.gov (United States)

    Karmakar, Srikanta; Mardanya, Sourav; Pal, Poulami; Baitalik, Sujoy

    2015-12-21

    A polypyridylimidazole-based bifunctional Os(II) complex of the type [(bpy)2Os(tpy-Hbzim-dipy)](ClO4)2 (1), where tpy-Hbzim-dipy = 4'-[4-(4,5-dipyridin-2-yl-1H-imidazol-2-yl)-phenyl]-2,2';6',2″-terpyridine and bpy = 2,2'-bipyridine, has been synthesized and structurally characterized for the construction of multifunctional logic devices. After coordination of an [Os(bpy)2](2+) unit to one of the two bidentate chelating sites, the complex offers a terpyridine motif for binding with cationic guests and an imidazole moiety for interacting with selective anionic species. Consequently, the anion- and cation-binding aspects of the metallorecptor were examined in solution and in the solid state by different spectroscopic and electrochemical methods. The complex behaves as a bifunctional sensor for F(-), AcO(-), CN(-), Fe(2+), and Cu(2+) ions in acetonitrile, whereas it is a highly selective chromogenic chemosensor for only CN(-) and Fe(2+) ions in water. Based on various output signals with a particular set of anionic and cationic inputs, the complex mimics the functions of two-input INHIBIT, OR, NOR, and XNOR logic gates, as well as three-input NOR logic behavior. More importantly, the complicated functions of a keypad lock and memory device were also nicely demonstrated by the complex. Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations also provide a rationale for properly understanding and interpreting the experimentally observed results.

  19. A multicommuted stop-flow system employing LEDs-based photometer for the sequential determination of anionic and cationic surfactants in water

    Energy Technology Data Exchange (ETDEWEB)

    Lavorante, Andre F. [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, CP 96, 13400-970, Piracicaba, SP (Brazil); Morales-Rubio, Angel; Guardia, Miguel de la [Department of Analytical Chemistry, Faculty of Chemistry, University of Valencia, Research Building, 50 Dr. Moliner St., 46100 Burjassot, Valencia (Spain); Reis, Boaventura F. [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, CP 96, 13400-970, Piracicaba, SP (Brazil)], E-mail: reis@cena.usp.br

    2007-09-26

    It has been developed an automatic stop-flow procedure for sequential photometric determination of anionic and cationic surfactants in a same sample of water. The flow system was based on multicommutation process that was designed employing two solenoid micro-pumps and six solenoid pinch valves, which under microcomputer control carry out fluid propelling and reagent solutions handling. A homemade photometer using a photodiode as detector and two light emitting diodes (LEDs) with emission at 470 nm (blue) and 650 nm (red) as radiation sources, which was tailored to allow the determination of anionic and cationic surfactants in waters. The procedure for anionic surfactant determination was based on the substitution reaction of methyl orange (MO) by the anionic surfactant sodium dodecylbenzene sulfonate (DBS) to form an ion-pair with the cetyl pyridine chloride (CPC). Features such as a linear response ranging from 0.35 to 10.5 mg L{sup -1} DBS (R = 0.999), a detection limit of 0.06 mg L{sup -1} DBS and a relative standard deviation of 0.6% (n = 11) were achieved. For cationic surfactant determination, the procedure was based on the ternary complex formation between cationic surfactant, Fe(III) and chromazurol S (CAS) using CPC as reference standard solution. A linear response range between 0.34 and 10.2 mg L{sup -1} CPC (R = 0.999), a detection limit of 0.05 mg L{sup -1} CPC and a relative standard deviation of 0.5% (n = 11) were obtained. In both cases, the sampling throughput was 60 determinations per hour. Reagents consumption of 7.8 {mu}g MO, 8.2 {mu}g CPC, 37.2 {mu}g CAS and 21.6 {mu}g Fe(III) per determination were achieved. Analyzing river water samples and applying t-test between the results found and those obtained using reference procedures for both surfactant types provide no significant differences at 95% confidence level.

  20. Muscle Weakness

    Directory of Open Access Journals (Sweden)

    Ali Al Kaissi MD, MSc

    2017-01-01

    Full Text Available Marked ligamentous hyperlaxity and muscle weakness/wasting associated with awkward gait are the main deficits confused with the diagnosis of myopathy. Seven children (6 boys and 1 girl with an average age of 8 years were referred to our department because of diverse forms of skeletal abnormalities. No definitive diagnosis was made, and all underwent a series of sophisticated investigations in other institutes in favor of myopathy. We applied our methodology through the clinical and radiographic phenotypes followed by targeted genotypic confirmation. Three children (2 boys and 1 girl were compatible with the diagnosis of progressive pseudorheumatoid chondrodysplasia. The genetic mutation was correlated with the WISP 3 gene actively expressed by articular chondrocytes and located on chromosome 6. Klinefelter syndrome was the diagnosis in 2 boys. Karyotyping confirmed 47,XXY (aneuploidy of Klinefelter syndrome. And 2 boys were finally diagnosed with Morquio syndrome (MPS type IV A as both showed missense mutations in the N-acetylgalactosamine-sulfate sulfatase gene. Misdiagnosis can lead to the initiation of a long list of sophisticated investigations.

  1. A high-resolution processing technique for improving the energy of weak signal based on matching pursuit

    Directory of Open Access Journals (Sweden)

    Shuyan Wang

    2016-05-01

    Full Text Available This paper proposes a new method to improve the resolution of the seismic signal and to compensate the energy of weak seismic signal based on matching pursuit. With a dictionary of Morlet wavelets, matching pursuit algorithm can decompose a seismic trace into a series of wavelets. We abstract complex-trace attributes from analytical expressions to shrink the search range of amplitude, frequency and phase. In addition, considering the level of correlation between constituent wavelets and average wavelet abstracted from well-seismic calibration, we can obtain the search range of scale which is an important adaptive parameter to control the width of wavelet in time and the bandwidth of frequency. Hence, the efficiency of selection of proper wavelets is improved by making first a preliminary estimate and refining a local selecting range. After removal of noise wavelets, we integrate useful wavelets which should be firstly executed by adaptive spectral whitening technique. This approach can improve the resolutions of seismic signal and enhance the energy of weak wavelets simultaneously. The application results of real seismic data show this method has a good perspective of application.

  2. One-pot fabrication of FRET-based fluorescent probe for detecting copper ion and sulfide anion in 100% aqueous media

    Science.gov (United States)

    Lv, Kun; Chen, Jian; Wang, Hong; Zhang, Peisheng; Yu, Maolin; Long, Yunfei; Yi, Pinggui

    2017-04-01

    The design of effective tools for detecting copper ion (Cu2 +) and sulfide anion (S2 -) is of great importance due to the abnormal level of Cu2 + and S2 - has been associated with an increase in risk of many diseases. Herein, we report on the fabrication of fluorescence resonance energy transfer (FRET) based fluorescent probe PF (PEI-FITC) for detecting Cu2 + and S2 - in 100% aqueous media via a facile one-pot method by covalent linking fluorescein isothiocyanate (FITC) with branched-polyethylenimine (b-PEI). PF could selectively coordinate with Cu2 + among 10 metal ions to form PF-Cu2 + complex, resulting in fluorescence quenching through FRET mechanism. Furthermore, the in situ generated PF-Cu2 + complex can be used to selectively detect S2 - based on the displacement approach, resulting in an off-on type sensing. There is no obvious interference from other anions, such as Cl-, NO3-, ClO4-, SO42 -, HCO3-, CO32 -, Br-, HPO42 -, F- and S2O32 -. In addition, PF was successfully used to determine Cu2 + and S2 - in human serum and tap water samples. Therefore, the FRET-based probe PF may provide a new method for selective detection of multifarious analysts in biological and environmental applications, and even hold promise for application in more complicated systems.

  3. Improved recovery of trace amounts of gold (III), palladium (II) and platinum (IV) from large amounts of associated base metals using anion-exchange resins.

    Science.gov (United States)

    Matsubara, I; Takeda, Y; Ishida, K

    2000-02-01

    The adsorption and desorption behaviors of gold (III), palladium (II) and platinum (IV) were surveyed in column chromatographic systems consisting of one of the conventional anion-exchange resins of large ion-exchange capacity and dilute thiourea solutions. The noble metals were strongly adsorbed on the anion-exchange resins from dilute hydrochloric acid, while most base metals did not show any marked adsorbability. These facts made it possible to separate the noble metals from a large quantity of base metals such as Ag (I), Al (III), Co (II), Cu (II), Fe (III), Mn (II), Ni (II), Pb (II), and Zn (II). Although it used to be very difficult to desorb the noble metals from the resins used, the difficulty was easily overcome by use of dilute thiourea solutions as an eluant. In the present study, as little as 1.00 microg of the respective noble metals was quantitatively separated and recovered from as much as ca. 10 mg of a number of metals on a small column by elution with a small amount of dilute thiourea solution. The present systems should be applicable to the separation, concentration and recovery of traces of the noble metals from a number of base metals coexisting in a more extended range of amounts and ratios.

  4. The effects of anionic electrolytes and human serum albumin on the LCST of poly(N-isopropylacrylamide)-based temperature-responsive copolymers.

    Science.gov (United States)

    Hiruta, Yuki; Nagumo, Yuhei; Suzuki, Yuichi; Funatsu, Takaaki; Ishikawa, Yuki; Kanazawa, Hideko

    2015-08-01

    Poly(N-isopropylacrylamide) (PNIPAm) is one of the most widely studied temperature-responsive polymers among those that have been applied to biomaterials science and technology. Here, we investigated the importance of interactions between PNIPAm-based copolymers and biological factors. The effects of a series of major anionic electrolytes in biological environments and of human serum albumin (HSA) on the lower critical solution temperature (LCST) of homo-PNIPAm and PNIPAm copolymers were studied, using either a hydrophobic monomer or a cationic monomer. We synthesized P(NIPAm-co-BMA3%) with butyl methacrylate (BMA) as a hydrophobic monomer and P(NIPAm-co-DMAPAm2%) with N,N-dimethylaminopropyl acrylamide (DMAPAm) as a cationic monomer. The LCST of PNIPAm and P(NIPAm-co-DMAPAm2%) decreased with increasing salt concentrations, and the effects of anions on each polymer corresponded to the Hofmeister series. The LCST of P(NIPAm-co-DMAPAm2%) was greatly affected by anionic electrolytes compared with those of homo-PNIPAm and P(NIPAm-co-BMA3%). While the LCST of homo-PNIPAm was not affected by HSA, the LCST of P(NIPAm-co-DMAPAm2%) decreased non-linearly with increasing HSA concentrations. These effects were due to the electrostatic interactions between the positively charged polymer chains and the negatively charged HSA, as well as the stabilization of polymer aggregations with HSA. Under physiological buffer conditions, the LCST of P(NIPAm-co-DMAPAm2%) was not significantly affected by the HSA concentration. These results indicated that depending on the types of copolymers used for biological applications, it is necessary to take into account the effect of biological media while designing polymers. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. A randomized controlled study on the effects of acetate-free biofiltration on organic anions and acid-base balance in hemodialysis patients.

    Science.gov (United States)

    Sánchez-Canel, Juan J; Hernández-Jaras, Julio; Pons-Prades, Ramón

    2015-02-01

    Metabolic acidosis correction is achieved by the transfer of bicarbonate and other buffer anions in dialysis. The aim of this study was to evaluate changes in the main anions of intermediary metabolism on standard hemodiafiltration (HDF) and on acetate-free biofiltration (AFB). A prospective, in-center, crossover study was carried out with 22 patients on maintenance dialysis. Patients were randomly assigned to start with 12 successive sessions of standard HDF with bicarbonate (34 mmol/L) and acetate dialysate (3 mmol/L) or 12 successive sessions of AFB without base in the dialysate. Acetate increased significantly during the standard HDF session from 0.078 ± 0.062 mmol/L to 0.156 ± 0.128 mmol/L (P acid-base equilibrium through a bicarbonate substitution fluid. It also prevents hyperacetatemia and restores internal homeostasis with less production of intermediary metabolites. © 2014 The Authors. Therapeutic Apheresis and Dialysis © 2014 International Society for Apheresis.

  6. [CHARACTERISTICS OF SURFACE ELECTROMYOGRAPHY AND ACID-BASE BALANCE IN PATIENTS WITH INTENSIVE CARE UNIT-ACQUIRED WEAKNESS].

    Science.gov (United States)

    Mejgal, A Yu; Tret'jakova, O G; Spasova, A P

    2015-01-01

    The study was aimed to search for correlation between parameters of surface electromyography and acid-base balance (ABB) in patients with intensive care unit-acquired weakness (ICUAW, n = 29, duration 7-180 days). The linear and nonlinear parameters of sEMG (mean frequency of spectrum, fractal and correlation dimension, correlation entropy) and ABB and their correlation coefficient with bed rest (BR) and duration of mechanical ventilation (MT) were computed. Here we report that in first 40 days sEMG parameters were indicative of the neurogenic process in the skeletal muscle, while within 41-100 days signs of the myogenic pathology were documented. The ABB parameters statistically signIficantly correlated with BR and MV duration. ICUAW exerts effect on the skeletal muscle. Within first 40 days this effect is actuated in a form of neuropathy, while further it has signs of myopathy. We argue that MV duration appear to be a pathogenic factor in these modifications.

  7. Highly sensitive and selective difunctional ruthenium(II) complex-based chemosensor for dihydrogen phosphate anion and ferrous cation.

    Science.gov (United States)

    Zheng, Ze-Bao; Duan, Zhi-Ming; Ma, Ying-Ying; Wang, Ke-Zhi

    2013-03-04

    The anion-interaction properties of a Ru(II) complex of [Ru(bpy)2(Htppip)](ClO4)2·H2O·DMF (RuL) {bpy =2,2'-bipyridine and Htppip =2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} were thoroughly investigated in CH3CN and CH3CN/H2O (50:1, v/v) solutions by UV-visible absorption, emission, and (1)H NMR spectra. These analyses revealed that RuL acts as an efficient "turn on" emission sensor for H2PO4(-), and a "turn off" sensor for F(-) and OAc(-); in addition, RuL exhibited slightly disturbed emission spectra in the presence of the other anions studied (Cl(-), Br(-), I(-), NO3(-), and ClO4(-)). The cation-sensing properties of RuL were also studied in both neat CH3CN and aqueous 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer (pH = 7.2)/CH3CN (71/1, v/v) solutions. RuL was found to exhibit a colorimetric sensing ability that was highly selective for Fe(2+), as evidenced by an obvious color change from pale yellow to light red-purple to the naked eye over the other cations studied (Na(+), Mg(2+), Ba(2+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Ag(+)). To obtain insights into the possible binding modes and the sensing mechanisms, (1)H NMR spectral analysis, luminescence lifetime measurements, and density functional theoretical calculations were also performed.

  8. A Water-Stable Dual-Channel Luminescence Sensor for UO22+Ions Based on an Anionic Terbium(III) Metal-Organic Framework.

    Science.gov (United States)

    Ye, Junwei; Bogale, Raji F; Shi, Yangwei; Chen, Yanzhen; Liu, Xigang; Zhang, Siqi; Yang, Yaoyao; Zhao, Jianzhang; Ning, Guiling

    2017-06-07

    A stable 3D Tb III -based metal-organic framework [Tb(BPDC) 2 ]⋅(CH 3 ) 2 NH 2 (DUT-101) was synthesized, and it is the first efficient dual-channel luminescence sensor for aqueous UO 2 2+ ions. DUT-101 contains an anionic three-dimensional framework and protonated dimethylamine molecules embedded within the channels. The intense green emission of DUT-101 could be highly selectively and sensitively quenched by UO 2 2+ ions even in the presence of other competing metal ions. A possible sensing mechanism was proposed based on both suppression of luminescence resonance energy transfer and enhancement of intermolecular electron transfer. Furthermore, visual green fluorescent test papers based on DUT-101 were fabricated and could be used to discriminate UO 2 2+ ions among various metal ions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of anionic salts in concentrate mixture and magnesium intake on some blood and urine minerals and acid-base balance of dry pregnant cows on grass silage based feeding

    Directory of Open Access Journals (Sweden)

    S. TAURIAINEN

    2008-12-01

    Full Text Available Twenty Friesian cows were randomly assigned to one of four prepartum diets in a 2 x 2 factorially designed experiment to determine the effect of anionic salts contained in a concentrate mixture and magnesium (Mg intake on some blood and urine minerals in cows fed a grass silage based diet. Four diets provided either 16 g or 33 g total dietary Mg/day, and had either a low or high cation-anion difference. Dietary cation-anion balance (DCAB of the diets, calculated as milliequivalents [(Na+ + K+ - (Cl- + S2-], was +31 mEq/kg dry matter (DM in the low DCAB group and +340 mEq/kg DM in the high DCAB group. DCAB was formulated using NH4Cl, (NH42SO4 and MgCl2 as anionic salts. Cows received grass silage (5.2 kg DM, hay (1.0 kg DM and concentrate mixture (1.5 kg DM until calving. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, the day after calving and 1 week following calving. Cows fed the low DCAB diet had a lower urinary pH (P

  10. Receptors for anions

    Energy Technology Data Exchange (ETDEWEB)

    Itsikson, N A; Chupakhin, O N [I. Ya. Postovsky Institute of Organic Synthesis, Urals Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation); Morzherin, Yu Yu; Matern, A I [B N Yeltsin Urals State Technical University - UPI (Russian Federation)

    2008-09-30

    The published data on receptors for anions with different geometry are generalised. Special attention is given to the analysis of binding abilities of organic ligands. Structural features of complex-forming agents and their properties are considered.

  11. Anion exchange polymer electrolytes

    Science.gov (United States)

    Kim, Yu Seung; Kim, Dae Sik

    2015-06-02

    Anion exchange polymer electrolytes that include guanidinium functionalized polymers may be used as membranes and binders for electrocatalysts in preparation of anodes for electrochemical cells such as solid alkaline fuel cells.

  12. A novel surface-confined glucaminium-based ionic liquid stationary phase for hydrophilic interaction/anion-exchange mixed-mode chromatography.

    Science.gov (United States)

    Qiao, Lizhen; Wang, Shuangyuan; Li, Hua; Shan, Yuanhong; Dou, Abo; Shi, Xianzhe; Xu, Guowang

    2014-09-19

    Glucaminium-based ionic liquids are a new class of recently developed ionic liquids and prepared by functionalizing the amine group of N-methyl-d-glucamine, which renders them good hydrophilicity due to the presence of the glucose structure and charged quaternary ammonium group. In the present study, a glucaminium-based ionic liquid N,N-diallyl-N-methyl-d-glucaminium bromide was synthesized and subsequently bonded to the surface of 3-mercaptopropyl modified silica materials through "thiol-ene" click chemistry. The obtained stationary phase was characterized by elemental analysis and infrared spectroscopy, and then packed as a HPLC column. A mixture of five nucleosides was used to characterize the separation performance of the obtained column under HILIC mode and the column efficiency was determined with cytidine as the test solute, reaching 80,000plates/m. Then, the retention behavior was evaluated by investigating the effect of various chromatographic factors on retention of different types of solutes, and the results revealed that the developed surface-confined glucaminium-based ionic liquid stationary phase exhibited a hydrophilic interaction/anion-exchange mixed-mode retention mechanism. Finally, two mixtures of nucleotides and flavonoids were separated on the glucaminium-based ionic liquid column, respectively under hydrophilic interaction and hydrophilic interaction/anion-exchange mixed-mode chromatography. In conclusion, the multimodal retention capabilities of the glucaminium-based ionic liquid column could offer a wider range of retention behavior and flexible selectivity toward polar and hydrophilic compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Effect of the Anion Activity on the Stability of Li Metal Anodes in Lithium-Sulfur Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Ruiguo [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Chen, Junzheng [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Han, Kee Sung [Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Xu, Wu [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Mei, Donghai [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Bhattacharya, Priyanka [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Engelhard, Mark H. [Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Mueller, Karl T. [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Department of Chemistry, Pennsylvania State University, University Park, PA 16802 USA; Liu, Jun [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Zhang, Ji-Guang [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA

    2016-03-29

    With the significant progress made in the development of cathodes in lithium-sulfur (Li-S) batteries, the stability of Li metal anodes becomes a more urgent challenge in these batteries. Here we report the systematic investigation of the stability of the anode/electrolyte interface in Li-S batteries with concentrated electrolytes containing various lithium salts. It is found that Li-S batteries using LiTFSI-based electrolytes are more stable than those using LiFSI-based electrolytes. The decreased stability is because the N-S bond in the FSI- anion is fairly weak and the scission of this bond leads to the formation of lithium sulfate (LiSOx) in the presence of polysulfide species. In contrast, even the weakest bond (C-S) in the TFSI- anion is stronger than the N-S bond in the FSI- anion. In the LiTFSI-based electrolyte, the lithium metal anode tends to react with polysulfide to form lithium sulfide (LiSx) which is more reversible than LiSOx formed in the LiTFSI-based electrolyte. This fundamental difference in the bond strength of the salt anions in the presence of polysulfide species leads to a large difference in the stability of the anode-electrolyte interface and performance of the Li-S batteries with electrolytes composed of these salts. Therefore, anion selection is one of the key parameters in the search for new electrolytes for stable operation of Li-S batteries.

  14. Several hemicyanine dyes as fluorescence chemosensors for cyanide anions

    Science.gov (United States)

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

    2016-05-01

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

  15. Dietary cation-anion difference effects on performance and acid-base status of lactating dairy cows: a meta-analysis.

    Science.gov (United States)

    Hu, W; Murphy, M R

    2004-07-01

    A meta-analysis was conducted to examine potential empirical relationships between dietary cation-anion difference (DCAD) (Na + K - Cl) and the response of lactating dairy cows. The database was developed from 12 studies published between 1984 and 1997 that included a total of 17 trials, 69 dietary treatments, and 230 cows. Results indicated that DCAD affected performance of lactating dairy cows. Maximum milk yield and feed intake were reached when DCAD was 34 and 40 meq/100 g of feed dry matter, respectively. Blood pH and HCO3 concentrations increased with DCAD, indicating an improved acid-base balance of lactating dairy cows. Changes in urinary pH and urinary excretion of Na, K, and Cl were consistent with varying DCAD, thus dietary acidity or alkalinity. The effects of DCAD were likely mediated via modification of acid-base status in the cows.

  16. Unexpectedly strong anion-π interactions on the graphene flakes.

    Science.gov (United States)

    Shi, Guosheng; Ding, Yihong; Fang, Haiping

    2012-05-30

    Interactions of anions with simple aromatic compounds have received growing attention due to their relevancy in various fields. Yet, the anion-π interactions are generally very weak, for example, there is no favorable anion-π interaction for the halide anion F(-) on the simplest benzene surface unless the H-atoms are substituted by the highly negatively charged F. In this article, we report a type of particularly strong anion-π interactions by investigating the adsorptions of three halide anions, that is, F(-), Cl(-), and Br(-), on the hydrogenated-graphene flake using the density functional theory. The anion-π interactions on the graphene flake are shown to be unexpectedly strong compared to those on simple aromatic compounds, for example, the F(-)-adsorption energy is as large as 17.5 kcal/mol on a graphene flake (C(84) H(24)) and 23.5 kcal/mol in the periodic boundary condition model calculations on a graphene flake C(113) (the supercell containing a F(-) ion and 113 carbon atoms). The unexpectedly large adsorption energies of the halide anions on the graphene flake are ascribed to the effective donor-acceptor interactions between the halide anions and the graphene flake. These findings on the presence of very strong anion-π interactions between halide ions and the graphene flake, which are disclosed for the first time, are hoped to strengthen scientific understanding of the chemical and physical characteristics of the graphene in an electrolyte solution. These favorable interactions of anions with electron-deficient graphene flakes may be applicable to the design of a new family of neutral anion receptors and detectors. Copyright © 2012 Wiley Periodicals, Inc.

  17. Comparison of Anionic, Cationic and Nonionic Surfactants as Dispersing Agents for Graphene Based on the Fluorescence of Riboflavin.

    Science.gov (United States)

    Mateos, Rocío; Vera, Soledad; Valiente, Mercedes; Díez-Pascual, Ana María; San Andrés, María Paz

    2017-11-22

    Fluorescence quenching is a valuable tool to gain insight about dynamic changes of fluorophores in complex systems. Graphene (G), a single-layered 2D nanomaterial with unique properties, was dispersed in surfactant aqueous solutions of different nature: non-ionic polyoxyethylene-23-lauryl ether (Brij L23), anionic sodium dodecylsulphate (SDS), and cationic hexadecyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium bromide (DTAB). The influence of the surfactant type, chain length and concentration, G total concentration and G/surfactant weight ratio on the fluorescence intensity of vitamin B₂ (riboflavin) was investigated. The quality of the different G dispersions was assessed by scanning and transmission electron microscopies (SEM and TEM). A quenching phenomenon of the fluorescence of riboflavin was found for G dispersions in all the surfactants, which generally becomes stronger with increasing G/surfactant weight ratio. For dispersions in the ionic surfactants, the quenching is more pronounced as the surfactant concentration raises, whilst the non-ionic one remains merely unchanged for the different G/Brij L23 weight ratios. More importantly, results indicate that DTAB solutions are the optimum media for dispersing G sheets, leading to an up to 16-fold drop in the fluorescence intensity. Understanding the mechanism in fluorescence quenching of G dispersions in surfactants could be useful for several optical applications.

  18. Interaction of bovine serum albumin with N-acyl amino acid based anionic surfactants: Effect of head-group hydrophobicity.

    Science.gov (United States)

    Ghosh, Subhajit; Dey, Joykrishna

    2015-11-15

    The function of a protein depends upon its structure and surfactant molecules are known to alter protein structure. For this reason protein-surfactant interaction is important in biological, pharmaceutical, and cosmetic industries. In the present work, interactions of a series of anionic surfactants having the same hydrocarbon chain length, but different amino acid head group, such as l-alanine, l-valine, l-leucine, and l-phenylalanine with the transport protein, bovine serum albumin (BSA), were studied at low surfactant concentrations using fluorescence and circular dichroism (CD) spectroscopy, and isothermal titration calorimetry (ITC). The results of fluorescence measurements suggest that the surfactant molecules bind simultaneously to the drug binding site I and II of the protein subdomain IIA and IIIA, respectively. The fluorescence as well as CD spectra suggest that the conformation of BSA goes to a more structured state upon surfactant binding at low concentrations. The binding constants of the surfactants were determined by the use of fluorescence as well as ITC measurements and were compared with that of the corresponding glycine-derived surfactant. The binding constant values clearly indicate a significant head-group effect on the BSA-surfactant interaction and the interaction is mainly hydrophobic in nature. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Anion exchange membranes based on terminally crosslinked methyl morpholinium-functionalized poly(arylene ether sulfone)s

    Science.gov (United States)

    Kwon, Sohyun; Rao, Anil H. N.; Kim, Tae-Hyun

    2018-01-01

    Azide-assisted terminal crosslinking of methyl morpholinium-functionalized poly(arylene ether sulfone) block copolymers yields products (xMM-PESs) suitable for use as anion exchange membranes. By combining the advantages of bulky morpholinium conductors and our unique polymer network crosslinked only at the termini of the polymer chains, we can produce AEMs that after the crosslinking show minimal loss in conductivity, yet with dramatically reduced water uptake. Terminal crosslinking also significantly increases the thermal, mechanical and chemical stability levels of the membranes. A high ion conductivity of 73.4 mS cm-1 and low water uptake of 26.1% at 80 °C are obtained for the crosslinked membrane with higher amount of hydrophilic composition, denoted as xMM-PES-1.5-1. In addition, the conductivity of the crosslinked xMM-PES-1.5-1 membrane exceeds that of its non-crosslinked counterpart (denoted as MM-PES-1.5-1) above 60 °C at 95% relative humidity because of its enhanced water retention capacity caused by the terminally-crosslinked structure.

  20. Comparison of Anionic, Cationic and Nonionic Surfactants as Dispersing Agents for Graphene Based on the Fluorescence of Riboflavin

    Directory of Open Access Journals (Sweden)

    Rocío Mateos

    2017-11-01

    Full Text Available Fluorescence quenching is a valuable tool to gain insight about dynamic changes of fluorophores in complex systems. Graphene (G, a single-layered 2D nanomaterial with unique properties, was dispersed in surfactant aqueous solutions of different nature: non-ionic polyoxyethylene-23-lauryl ether (Brij L23, anionic sodium dodecylsulphate (SDS, and cationic hexadecyltrimethylammonium bromide (CTAB and dodecyltrimethylammonium bromide (DTAB. The influence of the surfactant type, chain length and concentration, G total concentration and G/surfactant weight ratio on the fluorescence intensity of vitamin B2 (riboflavin was investigated. The quality of the different G dispersions was assessed by scanning and transmission electron microscopies (SEM and TEM. A quenching phenomenon of the fluorescence of riboflavin was found for G dispersions in all the surfactants, which generally becomes stronger with increasing G/surfactant weight ratio. For dispersions in the ionic surfactants, the quenching is more pronounced as the surfactant concentration raises, whilst the non-ionic one remains merely unchanged for the different G/Brij L23 weight ratios. More importantly, results indicate that DTAB solutions are the optimum media for dispersing G sheets, leading to an up to 16-fold drop in the fluorescence intensity. Understanding the mechanism in fluorescence quenching of G dispersions in surfactants could be useful for several optical applications.

  1. Bagging Weak Predictors

    DEFF Research Database (Denmark)

    Lukas, Manuel; Hillebrand, Eric

    Relations between economic variables can often not be exploited for forecasting, suggesting that predictors are weak in the sense that estimation uncertainty is larger than bias from ignoring the relation. In this paper, we propose a novel bagging predictor designed for such weak predictor...... variables. The predictor is based on a test for finitesample predictive ability. Our predictor shrinks the OLS estimate not to zero, but towards the null of the test which equates squared bias with estimation variance. We derive the asymptotic distribution and show that the predictor can substantially lower...

  2. Weak bond screening system

    Science.gov (United States)

    Chuang, S. Y.; Chang, F. H.; Bell, J. R.

    Consideration is given to the development of a weak bond screening system which is based on the utilization of a high power ultrasonic (HPU) technique. The instrumentation of the prototype bond strength screening system is described, and the adhesively bonded specimens used in the system developmental effort are detailed. Test results obtained from these specimens are presented in terms of bond strength and level of high power ultrasound irradiation. The following observations were made: (1) for Al/Al specimens, 2.6 sec of HPU irradiation will screen weak bond conditions due to improper preparation of bonding surfaces; (2) for composite/composite specimens, 2.0 sec of HPU irradiation will disrupt weak bonds due to under-cured conditions; (3) for Al honeycomb core with composite skin structure, 3.5 sec of HPU irradiation will disrupt weak bonds due to bad adhesive or oils contamination of bonding surfaces; and (4) for Nomex honeycomb with Al skin structure, 1.3 sec of HPU irradiation will disrupt weak bonds due to bad adhesive.

  3. Anion-macrodipole interactions: self-assembling oligourea/amide macrocycles as anion transporters that respond to membrane polarization.

    OpenAIRE

    Hennig Andreas; Fischer Lucile; Guichard Gilles; Matile Stefan

    2009-01-01

    Macrocyclic urea/amide hybrids are introduced as functional anion selective membrane transporters in lipid bilayer membranes. Six derivatives with varying side chains (aliphatic and aromatic) and conformations (parallel and antiparallel carbonyl dipoles) are investigated by fluorescence methods among which the more active aromatic derivatives were selected for an in depth study. Strong response of transport activity toward anion exchange and weak response toward cation exchange establish anio...

  4. Analysis of the transmission characteristics of radio waves in inhomogeneous weakly ionized dusty plasma sheath based on high order SO-DGTD

    Directory of Open Access Journals (Sweden)

    Bing Wei

    Full Text Available Based on high order hierarchical basis function and the ideal of shift operator, shift operator discontinuous Galerkin time domain (SO-DGTD technique for dealing with weakly ionized dusty plasma electromagnetic problems is proposed. Lagrange interpolation is used to transform the metallic blunt cone aircraft with weakly ionized dusty plasma sheath from geometric model built by COMSOL to electromagnetic computational model. In the case of two-dimensional transverse magnetic (TM wave, the electromagnetic wave propagation in weakly ionized dusty plasma sheath is calculated by SO-DGTD technique. And then, the influence of dust particle concentration and dust radius on the radio wave transmission is analyzed, and the radio wave propagation characteristics pass through the sheath is compared with the flight speed and height change. Keywords: SO-DGTD, Weakly ionized dusty plasma sheath, High order hierarchical basis function

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

    Energy Technology Data Exchange (ETDEWEB)

    Bowman-James, Kristen

    2004-12-01

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

  6. Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

    Directory of Open Access Journals (Sweden)

    Jignesh Lunagariya

    2017-07-01

    Full Text Available The non-ionic triblock copolymer, Pluronic® F127, has been selected to observe its interaction with ionic liquids (ILs in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs.

  7. Biocompatible anionic polymeric microspheres as priming delivery system for effetive HIV/AIDS Tat-based vaccines.

    Directory of Open Access Journals (Sweden)

    Fausto Titti

    Full Text Available Here we describe a prime-boost regimen of vaccination in Macaca fascicularis that combines priming with novel anionic microspheres designed to deliver the biologically active HIV-1 Tat protein and boosting with Tat in Alum. This regimen of immunization modulated the IgG subclass profile and elicited a balanced Th1-Th2 type of humoral and cellular responses. Remarkably, following intravenous challenge with SHIV89.6Pcy243, vaccinees significantly blunted acute viremia, as compared to control monkeys, and this control was associated with significantly lower CD4+ T cell depletion rate during the acute phase of infection and higher ability to resume the CD4+ T cell counts in the post-acute and chronic phases of infection. The long lasting control of viremia was associated with the persistence of high titers anti-Tat antibodies whose profile clearly distinguished vaccinees in controllers and viremics. Controllers, as opposed to vaccinated and viremic cynos, exhibited significantly higher pre-challenge antibody responses to peptides spanning the glutamine-rich and the RGD-integrin-binding regions of Tat. Finally, among vaccinees, titers of anti-Tat IgG1, IgG3 and IgG4 subclasses had a significant association with control of viremia in the acute and post-acute phases of infection. Altogether these findings indicate that the Tat/H1D/Alum regimen of immunization holds promise for next generation vaccines with Tat protein or other proteins for which maintenance of the native conformation and activity are critical for optimal immunogenicity. Our results also provide novel information on the role of anti-Tat responses in the prevention of HIV pathogenesis and for the design of new vaccine candidates.

  8. Multi-channel receptors based on thiopyrylium functionalised with macrocyclic receptors for the recognition of transition metal cations and anions.

    Science.gov (United States)

    Abalos, T; Jiménez, D; Moragues, M; Royo, S; Martínez-Máñez, R; Sancenón, F; Soto, J; Costero, A M; Parra, M; Gil, S

    2010-04-14

    We report herein the synthesis and characterization of a family of ligands containing different cation binding sites covalently connected to a thiopyrylium signalling reporter. The receptors L1-L6 are able to signal the presence of certain metal cations via three different channels; i.e. electrochemically, fluorogenically and chromogenically. An acetonitrile solution of L1-L6 shows a bright blue colour due to a charge-transfer band in the 575-585 nm region. The colour variation in acetonitrile of L1-L6 in the presence of the metal cations Ag+, Cd2+, Cu2+, Fe3+, Hg2+, Ni2+, Pb2+ and Zn2+ has been studied. A selective hypsochromic shift of the blue band was found for the systems L4-Pb2+ and L5-Hg2+. Additionally, L1-L6 are poorly fluorescent but coordination with certain metal cations induces an enhancement of the fluorescence at ca 500 nm. For instance, the presence of Cu2+ and Fe3+ induced a remarkable 42-fold and 45-fold enhancement in the emission intensity of L1 centred at 500 nm, respectively. Also remarkable was the 18-fold enhancement observed for L4 and L5 in the presence of Fe3+ and Cu2+, respectively. The electrochemical behaviour of receptors L1-L6 was studied in acetonitrile using platinum as a working electrode and [Bu4N][BF4] as a supporting electrolyte. This family of receptors showed a one-electron reversible redox process at ca. -0.46 V versus sce attributed to the reduction of the thiopyrylium group. A moderate anodic shift in the presence of certain metal cations was observed. The effect in the UV-visible spectra of acetonitrile solutions of receptor L1-L6 in the presence of anions was also studied. A remarkable bleaching was found in the presence of cyanide.

  9. Weak lensing with GEST

    Science.gov (United States)

    Rhodes, J. D.; Bennett, D. P.; Kaiser, N.

    2001-12-01

    Weak lensing by large-scale structure (cosmic shear) provides an opportunity to directly observe the dark matter in the universe. Current ground-based and space-based surveys have demonstrated the efficacy of this technique in determining the mass distribution and thus placing constraints on cosmological parameters such as Ω m, σ 8, and the bias parameter b. Current surveys have been hampered by the comparatively low resolution of ground-based telescopes and the small field of view of HST. To make significant progress in this field, wide field space-based surveys are needed. The Galactic Exoplanet Survey Telescope (GEST) will be able to provide 500- 1000 sqare degrees with a resolution of better than 0.2 arcseconds in multiple filters. This will make it an ideal instrument for a weak lensing survey.

  10. Retention prediction of low molecular weight anions in ion chromatography based on quantitative structure-retention relationships applied to the linear solvent strength model.

    Science.gov (United States)

    Park, Soo Hyun; Haddad, Paul R; Talebi, Mohammad; Tyteca, Eva; Amos, Ruth I J; Szucs, Roman; Dolan, John W; Pohl, Christopher A

    2017-02-24

    Quantitative Structure-Retention Relationships (QSRRs) represent a popular technique to predict the retention times of analytes, based on molecular descriptors encoding the chemical structures of the analytes. The linear solvent strength (LSS) model relating the retention factor, k to the eluent concentration (log k=a-blog [eluent]), is a well-known and accurate retention model in ion chromatography (IC). In this work, QSRRs for inorganic and small organic anions were used to predict the regression parameters a and b in the LSS model (and hence retention times) for these analytes under a wide range of eluent conditions, based solely on their chemical structures. This approach was performed on retention data of inorganic and small organic anions from the "Virtual Column" software (Thermo Fisher Scientific). These retention data were recalibrated via a "porting" methodology on three columns (AS20, AS19, and AS11HC), prior to the QSRR modeling. This provided retention data more applicable on recently produced columns which may exhibit changes of column behavior due to batch-to-batch variability. Molecular descriptors for the analytes were calculated with Dragon software using the geometry-optimized molecular structures, employing the AM1 semi-empirical method. An optimal subset of molecular descriptors was then selected using an evolutionary algorithm (EA). Finally, the QSRR models were generated by multiple linear regression (MLR). As a result, six QSRR models with good predictive performance were successfully derived for a- and b-values on three columns (R(2)>0.98 and RMSE0.7 and RMSEP<0.4). Moreover, it was demonstrated that the obtained QSRR models for the a- and b-values can predict the retention times for new analytes with good accuracy and predictability (R(2) of 0.98, RMSE of 0.89min, Qext(F3)(2) of 0.96 and RMSEP of 1.18min). Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Biorelevant Dissolution Models for a Weak Base To Facilitate Formulation Development and Overcome Reduced Bioavailability Caused by Hypochlordyria or Achlorhydria.

    Science.gov (United States)

    Kou, Dawen; Dwaraknath, Sudharsan; Fischer, Yannick; Nguyen, Daniel; Kim, Myeonghui; Yiu, Hiuwing; Patel, Preeti; Ng, Tania; Mao, Chen; Durk, Matthew; Chinn, Leslie; Winter, Helen; Wigman, Larry; Yehl, Peter

    2017-10-02

    In this study, two dissolution models were developed to achieve in vitro-in vivo relationship for immediate release formulations of Compound-A, a poorly soluble weak base with pH-dependent solubility and low bioavailability in hypochlorhydric and achlorhydric patients. The dissolution models were designed to approximate the hypo-/achlorhydric and normal fasted stomach conditions after a glass of water was ingested with the drug. The dissolution data from the two models were predictive of the relative in vivo bioavailability of various formulations under the same gastric condition, hypo-/achlorhydric or normal. Furthermore, the dissolution data were able to estimate the relative performance under hypo-/achlorhydric and normal fasted conditions for the same formulation. Together, these biorelevant dissolution models facilitated formulation development for Compound-A by identifying the right type and amount of key excipient to enhance bioavailability and mitigate the negative effect of hypo-/achlorhydria due to drug-drug interaction with acid-reducing agents. The dissolution models use readily available USP apparatus 2, and their broader utility can be evaluated on other BCS 2B compounds with reduced bioavailability caused by hypo-/achlorhydria.

  12. Combined use of ordered mesoporous silica and precipitation inhibitors for improved oral absorption of the poorly soluble weak base itraconazole.

    Science.gov (United States)

    Van Speybroeck, Michiel; Mols, Raf; Mellaerts, Randy; Thi, Thao Do; Martens, Johan A; Van Humbeeck, Jan; Annaert, Pieter; Van den Mooter, Guy; Augustijns, Patrick

    2010-08-01

    The release of poorly soluble drugs from mesoporous silicates is often associated with the generation of supersaturation, which implies the risk of drug precipitation and reduced availability for absorption. The aim of this study was to enhance the in vivo performance of an ordered mesoporous silicate (SBA-15) by combining it with the precipitation inhibitors hydroxypropylmethylcellulose (HPMC) and hydroxypropylmethylcellulose acetate succinate (HPMCAS). The poorly soluble weak base itraconazole was used as a model compound. Formulations were prepared by physically blending itraconazole-loaded SBA-15 with the precipitation inhibitors. In vitro release experiments implementing a transfer from simulated gastric fluid to simulated intestinal fluid were used to evaluate the pharmaceutical performance. Subsequently, the formulations were evaluated in vivo in rats. When high enough amounts of HPMC were co-administered with itraconazole-loaded SBA-15 (itraconazole:SBA-15:HPMC 1:4:6), the extent of absorption was increased by more than 60% when compared to SBA-15 without precipitation inhibitors (AUC 14,937+/-1617 versus 8987+/-2726nMh). HPMCAS was found ineffective in enhancing the in vivo performance of SBA-15 due to its insolubility in the stomach. The results of this study demonstrate that the pharmaceutical performance of SBA-15 is enhanced through addition of an appropriate precipitation inhibitor.

  13. TiB₂-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions.

    Science.gov (United States)

    Ziemnicka-Sylwester, Marta

    2013-05-10

    TiB₂-based ceramic matrix composites (CMCs) were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic "in situ" reaction of TiB₂ formation and the "tailing" synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB₂ vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB₂:B₄C molar ratio of 0.96, which corresponds to 40 vol% of TiB₂ in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB₂:B₄C molar ratio of 2.16 or above. Finally B13C₂ was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB₂ grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure), were obtained for material containing 80 vol% of TiB₂, fabricated using a graphite precursor of 2 μm.

  14. Lipid-Based Formulations Can Enable the Model Poorly Water-Soluble Weakly Basic Drug Cinnarizine to Precipitate in an Amorphous-Salt Form during in Vitro Digestion

    DEFF Research Database (Denmark)

    Khan, Jamal; Rades, Thomas; Boyd, Ben J

    2016-01-01

    The tendency for poorly water-soluble weakly basic drugs to precipitate in a noncrystalline form during the in vitro digestion of lipid-based formulations (LBFs) was linked to an ionic interaction between drug and fatty acid molecules produced upon lipid digestion. Cinnarizine was chosen as a model...... from the starting free base crystalline material to the hydrochloride salt, thus supporting the case that ionic interactions between weak bases and fatty acid molecules during digestion are responsible for producing amorphous-salts upon precipitation. The conclusion has wide implications...... weakly basic drug and was dissolved in a medium-chain (MC) LBF, which was subject to in vitro lipolysis experiments at various pH levels above and below the reported pKa value of cinnarizine (7.47). The solid-state form of the precipitated drug was analyzed using X-ray diffraction (XRD), Fourier...

  15. Weak bases and ionophores rapidly and reversibly raise the pH of endocytic vesicles in cultured mouse fibroblasts

    Science.gov (United States)

    1982-01-01

    It has been shown that endocytic vesicles in BALB/c 3T3 cells have a pH of 5.0 (Tycko and Maxfield, Cell, 28:643-651). In this paper, a method for measuring the effect of various agents, including weak bases and ionophores, on the pH of endocytic vesicles is presented. The method is based on the increase in fluorescein fluorescence with 490-nm excitation as the pH is raised above 5.0. Intensities of cells were measured using a microscope spectrofluorometer after internalization of fluorescein-labeled alpha 2-macroglobulin by receptor-mediated endocytosis. The increase in endocytic vesicle pH was determined from the increase in fluorescence after addition of various concentrations of the test agents. The following agents increased endocytic vesicle pH above 6.0 at the indicated concentrations: monensin (6 microM), FCCP (10 microM), chloroquine (140 microM), ammonia (5 mM), methylamine (10 mM). The ability of many of these agents to raise endocytic vesicle pH may account for many of their effects on receptor-mediated endocytosis. Dansylcadaverine caused no effect on vesicle pH at 1 mM. The observed increases in vesicle pH were rapid (1-2 min) and could be reversed by removal of the perturbant. This reversibility indicates that the vesicles themselves contain a mechanism for acidification. The increase in vesicle pH due to these treatments can be observed visually using an SIT video camera. Using this method, it is shown that endocytic vesicles become acidic at very early times (i.e., within 5-7 min of continuous uptake at 37 degrees C). PMID:6183281

  16. Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Imidazolium-Based Ionic Liquids: Effects of Anion Species and Cation Alkyl Groups.

    Science.gov (United States)

    Kakinuma, Shohei; Ishida, Tateki; Shirota, Hideaki

    2017-01-12

    The temperature dependence of the intermolecular vibrational dynamics in imidazolium-based ionic liquids (ILs) with 10 different anions was studied by femtosecond Raman-induced Kerr effect spectroscopy. For all ILs investigated in this study, the intensity in the low-frequency region below 50 cm-1 increases, and the spectral density in the high-frequency region above 80 cm-1 decreases (and shows a redshift) with increasing temperature. The first phenomenon would be attributed to the activation of the translational vibrational motions, whereas the second one is ascribed to the slowing librational motion of the imidazolium ring with increasing temperature. Calculated spectra of the density of states for the intermolecular vibrations of 1-butyl-3-methylimidazolium hexafluorophosphate, which is one of the experiment samples studied here, obtained by molecular dynamics simulation agreed well with the experimental results and confirmed the spectral assignments. When we compared the difference spectra between spectra measured at various temperatures and the spectrum measured at 293 K, a clear difference was found in the ∼50 cm-1 region of the Kerr spectra of 1-butyl-3-methylimidazolium thiocyanate and 1-butyl-3-methylimidazolium dicyanamide from those of the other ILs. The difference might have originated from the librational motions of the corresponding anions. We also compared the temperature-dependent Kerr spectra of hexafluorophosphate salts of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-heptyl-3-methylimidazolium cations. These ILs showed a similar temperature dependence, which was not affected by the alkyl group length. The temperature-dependent viscosities and glass transition temperatures of the ILs were also estimated to determine their fragilities.

  17. Effect of cation species on surface-induced phase transition observed for platinum complex anions in platinum electrodeposition using nanoporous silicon.

    Science.gov (United States)

    Koda, Ryo; Koyama, Akira; Fukami, Kazuhiro; Nishi, Naoya; Sakka, Tetsuo; Abe, Takeshi; Kitada, Atsushi; Murase, Kuniaki; Kinoshita, Masahiro

    2014-08-21

    In an earlier work [K. Fukami et al., J. Chem. Phys. 138, 094702 (2013)], we reported a transition phenomenon observed for platinum complex anions in our platinum electrodeposition experiment using nanoporous silicon. The pore wall surface of the silicon electrode was made hydrophobic by covering it with organic molecules. The anions are only weakly hydrated due to their large size and excluded from the bulk aqueous solution to the hydrophobic surface. When the anion concentration in the bulk was gradually increased, at a threshold the deposition behavior exhibited a sudden change, leading to drastic acceleration of the electrochemical deposition. It was shown that this change originates from a surface-induced phase transition: The space within a nanopore is abruptly filled with the second phase in which the anion concentration is orders of magnitude higher than that in the bulk. Here we examine how the platinum electrodeposition behavior is affected by the cation species coexisting with the anions. We compare the experimental results obtained using three different cation species: K(+), (CH3)4N(+), and (C2H5)4N(+). One of the cation species coexists with platinum complex anions [PtCl4](2-). It is shown that the threshold concentration, beyond which the electrochemical deposition within nanopores is drastically accelerated, is considerably dependent on the cation species. The threshold concentration becomes lower as the cation size increases. Our theoretical analysis suggests that not only the anions but also the cations are remarkably enriched in the second phase. The remarkable enrichment of the anions alone would give rise to the energetic instability due to electrostatic repulsive interactions among the anions. We argue that the result obtained cannot be elucidated by the prevailing view based on classical electrochemistry. It is necessitated to consult a statistical-mechanical theory of confined aqueous solutions using a molecular model for water.

  18. From anion receptors to transporters.

    Science.gov (United States)

    Gale, Philip A

    2011-03-15

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

  19. Potentiometric anion selective sensors

    NARCIS (Netherlands)

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

    1999-01-01

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

  20. The characteristics of weakly forced mountain-to-plain precipitation systems based on radar observations and high-resolution reanalysis

    Science.gov (United States)

    Xiao, Xian; Sun, Juanzhen; Chen, Mingxuan; Qie, Xiushu; Wang, Yingchun; Ying, Zhuming

    2017-03-01

    The metropolis of Beijing in China is located on a plain adjacent to high mountains to its northwest and the gulf of the Bohai Sea to its southeast. One of the most challenging forecast problems for Beijing is to predict whether thunderstorms initiating over the mountains will propagate to the adjacent plains and intensify. In this study, 18 warm season convective cases between 2008 and 2013 initiating on the mountains and intensifying on the plains under weak synoptic forcing were analyzed to gain an understanding of their characteristics. The statistical analysis was based on mosaic reflectivity data from six operational Doppler radars and reanalysis data produced by the Four-Dimensional Variational Doppler Radar Analysis System (VDRAS). The analysis of the radar reflectivity data shows that convective precipitation strengthened on the plains at certain preferred locations. To investigate the environmental conditions favoring the strengthening of the mountain-to-plain convective systems, statistical diagnoses of the rapid-update (12 min) 3 km reanalyses from VDRAS for the 18 cases were performed by computing the horizontal and temporal means of convective available potential energy, convective inhibition, vertical wind shear, and low-level wind for the plain and mountain regions separately. The results were compared with those from a baseline representing the warm season average and from a set of null cases and found considerable differences in these fields between the three data sets. The mean distributions of VDRAS reanalysis fields were also examined. The results suggest that the convergence between the low-level outflows associated with cold pools and the south-southeasterly environmental flows corresponds well with the preferred locations of convective intensification on the plains.

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

    Science.gov (United States)

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

    2013-01-11

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

  2. Real-time weak signal detecting using FPGA-based Duffing oscillator with auto-damping and high speed ADC

    Science.gov (United States)

    Shen, Zhongtao; Feng, Changqing

    2017-05-01

    In this paper, a hardware real-time weak signal detection method using Field-Programmable Gate Array (FPGA) Duffing Oscillator (DUOS) and high speed Analog-to-Digital Converter (ADC) is presented. In the design, the Xilinx Kintex-7 FPGA is chosen as the controller and the DUOS weak signal detecting algorithm is implemented in it with single floating precision. The ADS5409, a dual-channel, 12-bit, 900 MSPS ADC of TI, is used for data acquisition. Besides, to guarantee the same detection Signal-Noise Ratio (SNR) for signals of different amplitudes, a signal auto-damping strategy is adopted in the FPGA, which can adjust the amplitudes of the input signals automatically. The method introduced in this paper achieves not only the ability of efficient weak signal detection in noisy environment but also the advantages of hardware processing such as real-time, low power and so on.

  3. Methods development for separation of inorganic anions, organic acids and bases, and neutral organic compounds by ion chromatography and capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie [Iowa State Univ., Ames, IA (United States)

    1999-04-01

    A novel anion-exchange resin containing three amine groups was prepared by reaction of a chloromethylated polystyrene-divinylbenzene (PS-DVB) resin with diethylenetriamine. After being protonated by contact with an aqueous acid, this resin can be used for ion chromatographic separation of anions. The charge on the resins can be varied from +1 to +3 by changing the mobile phase pH. The selectivity of the new ion exchangers for various inorganic anions was quite different from that of conventional anion exchangers. The performance of this new anion exchanger was studied by changing the pH and the concentration of the eluent, and several different eluents were used with some common anions as testing analytes. Conductivity detection and UV-visible detection were applied to detect the anions after separation. The new resin can also be used for HPLC separation of neutral organic compounds. Alkylphenols and alkylbenzenes were separated with this new polymeric resin, and excellent separations were obtained under simple conditions. This report contains Chapter 1: General introduction and Chapter 6: General conclusions.

  4. Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

    Science.gov (United States)

    Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei

    2017-05-01

    Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO3 LDHs, Zn-Al-Cl LDHs and Zn-Al-VOx LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VOx LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

  5. The effect of pH on the uptake and toxicity of the bivalent weak base chloroquine tested on Salix viminalis and Daphnia magna

    DEFF Research Database (Denmark)

    Rendal, Cecilie; Kusk, Kresten Ole; Trapp, Stefan

    2011-01-01

    , and therefore a higher toxicity can be expected. The current study examines the pHdependent toxicity and bioaccumulation of the bivalent weak base chloroquine (pKa: 10.47 and 6.33, log KOW 4.67) tested on Salix viminalis (basket willow) and Daphnia magna (water flea). The transpiration rates of hydroponically...

  6. Analysis of the transmission characteristics of radio waves in inhomogeneous weakly ionized dusty plasma sheath based on high order SO-DGTD

    Science.gov (United States)

    Wei, Bing; Li, Linqian; Yang, Qian; Ge, Debiao

    Based on high order hierarchical basis function and the ideal of shift operator, shift operator discontinuous Galerkin time domain (SO-DGTD) technique for dealing with weakly ionized dusty plasma electromagnetic problems is proposed. Lagrange interpolation is used to transform the metallic blunt cone aircraft with weakly ionized dusty plasma sheath from geometric model built by COMSOL to electromagnetic computational model. In the case of two-dimensional transverse magnetic (TM) wave, the electromagnetic wave propagation in weakly ionized dusty plasma sheath is calculated by SO-DGTD technique. And then, the influence of dust particle concentration and dust radius on the radio wave transmission is analyzed, and the radio wave propagation characteristics pass through the sheath is compared with the flight speed and height change.

  7. Colorimetric and fluorimetric response of Schiff base molecules towards fluoride anion, solution test kit fabrication, logical interpretations and DFT-D3 study.

    Science.gov (United States)

    Ghosh, Pritam; Roy, Biswajit Gopal; Jana, Saibal; Mukhopadhyay, Subhra Kanti; Banerjee, Priyabrata

    2015-08-21

    Two newly synthesized Schiff base molecules are herein reported as anion sensors. -NO2 substituted receptor (P1) is comparatively more acidic and can sense F(-), OAc(-) and H2PO4(-), whereas -CN substituted receptor (P2) is less acidic and is selective for F(-) only. Reversible UV-Vis response for both receptors with F(-) can mimic multiple logic gate functions, and several complex electronic circuits based on XNOR, XOR, OR, AND, NOT and NOR logic operations with 'Write-Read-Erase-Read' options have been executed. Interesting 'turn on and off' fluorescence responses were noticed for the receptors with F(-). Intracellular F(-) detection as a diagnosis of non-skeletal fluorosis was successful using a fluorescence microscope with Candida albicans (prokaryotic cell, a diploid fungus) and pollen grains of Tecoma stans (eukaryotic cell) incubated in 10(-6) M fluoride-contaminated hand-pump water collected from Bankura, West Bengal, India. Furthermore, a solution test kit was fabricated for easy and selective detection of F(-) in an aqueous solvent.

  8. A simple and efficient purification platform for monoclonal antibody production based on chromatin-directed cell culture clarification integrated with precipitation and void-exclusion anion exchange chromatography.

    Science.gov (United States)

    Chen, Quan; Abdul Latiff, Sarah Maria; Toh, Phyllicia; Peng, Xinying; Hoi, Aina; Xian, Mo; Zhang, Haibo; Nian, Rui; Zhang, Wei; Gagnon, Pete

    2016-10-20

    Protein A affinity chromatography, featured by its robustness and high-specificity, is still dominant as a first capture step for the purification of immunoglobulin G monoclonal antibodies (IgG mAbs). However, the material and operational costs of protein A are universally recognized as high, and its productivity is also limited as column mode. In order to overcome these limitations, industry is increasingly considering the use of non-protein A-based processes for IgG purification. In this study, sodium citrate precipitation (SCP) was developed as the primary purification step, and chromatin-directed cell culture clarification was demonstrated to significantly elevate the purification capability. Additional 0.05% (w/v) of Tween 20 was shown to effectively reduce the residual free antibody light chain (LC) during precipitation. The resuspended IgG was further polished by void-exclusion anion exchange chromatography (VEAX), which supported protein loading without buffer adjustment. The non-histone host cell protein (nh-HCP) content in the final product was about 5ppm and histone HCP below limit of detection (LOD). DNA was reduced to less than 1ppb, and aggregates/free LC less than 0.1%. The overall IgG recovery was 87.2%. A simple and efficient purification platform with only one-column step was therefore established, providing a more promising alternative to the current prevailing protein A-based purification platforms. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Novel chlorambucil-conjugated anionic linear-globular PEG-based second-generation dendrimer: in vitro/in vivo improved anticancer activity

    Directory of Open Access Journals (Sweden)

    Assadi A

    2016-09-01

    Full Text Available Artin Assadi,1 Vahideh Sharifi Najafabadi,1 Seyed Ataollah Sadat Shandiz,2 Azadah Shayeq Boroujeni,1 Sepehr Ashrafi,1 Ali Zaman Vaziri,1 Seyedeh Masoumeh Ghoreishi,1 Mohammad Reza Aghasadeghi,3 Seyed Esmaeil Sadat Ebrahimi,4 Morteza Pirali-Hamedani,4 Mehdi Shafiee Ardestani1 1Department of Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, 2Young Researchers and Elite Club, East Tehran Branch, Islamic Azad University, 3Department of Hepatitis and AIDS, Pasteur Institute of Iran, 4Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran Abstract: Evaluating the efficacy of anticancer drugs is an evolving and research-oriented issue. The objective of this study was to reduce the insolubility of chlorambucil (CBL in water and improve the anticancer activity of CBL in vitro and in vivo through the conjugation of CBL with anionic linear-globular dendrimer (second generation, G2. In the current study, the anticancer activity among three groups that include CBL, CBL–G2 dendrimer, and control was measured in vitro and in vivo. In vitro studies showed that G2 anionic linear-globular polyethylene-glycol-based dendrimer, which conjugated to the CBL exterior through an ester linkage, was able to significantly improve the treatment efficacy over clinical CBL alone with respect to proliferation assay, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl-2H-tetrazolium-5-carboxanilide; half maximal inhibitory concentration (IC50 was calculated to be 141 µg/mL for CBL alone and 27.7 µg/mL for CBL–G2 dendrimer; P<0.05. In addition, CBL–G2 dendrimer conjugate forestalled the growth of MCF-7 cancerous cells in addition to enhancing the number of apoptotic and necrotic cells as demonstrated by an annexin V-fluorescein isothiocyanate assay. CBL–G2 dendrimer conjugate was able to checkmate antiapoptotic Bcl-2 expression and Bcl-2/Bax ratio in a large scale compared with the control group and

  10. Anion-Directed Metallocages: A Study on the Tendency of Anion Templation.

    Science.gov (United States)

    Wu, Jing-Yun; Zhong, Ming-Shiou; Chiang, Ming-Hsi

    2017-11-13

    Self-assembly of Cu(NO3 )2 ⋅3 H2 O and di(3-pyridylmethyl)amine (dpma) with addition of different acids (HNO3 , HOAc, HCl, HClO4 , HOTf, HPF6 , HBF4 , and H2 SO4 ) afforded a family of anion-templated tetragonal metallocages with a cationic prismatic structure of [(G(n-) )⊂{Cu2 (Hdpma)4 }]((8-n)+) (G(n-) =NO3(-) , PF6(-) , SiF6(2-) ) with different ligating anions/solvents (NO3(-) , Cl(-) , ClO4(-) , OTf(-) , H2 O) outside the cage. Systematic competitive experiments have rationalized the tendency of anion templation towards the formation of metallocages [(G(n-) )⊂{Cu2 (Hdpma)4 }]((8-n)+) as occurring in the order SiF6(2-) ≈PF6(-) >NO3(-) >SO4(2-) ≈ClO4(-) ≈BF4(-) . This sequence is mostly elucidated by shape control over size selectivity and electrostatic attraction between the cationic {Cu2 (Hdpma)4 }(8+) host and the anionic guests. In addition, these results have also roughly ranked the anion coordination ability in the order Cl(-) , ClO4(-) , OTf(-) >NO3(-) >BF4(-) , CH3 SO4(-) . Magnetic studies of metallocages 1 t and 2-4 suggest that the fitted magnetic interaction, being weakly magnetically coupled overall, is interpreted as a result of the combination of intracage ferromagnetic coupling integrals and intercage antiferromagnetic exchange; both contributions are very weak and comparable in strength. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Exercise-based rehabilitation after hospital discharge for survivors of critical illness with intensive care unit?acquired weakness: A pilot feasibility trial ? ??

    OpenAIRE

    Connolly, Bronwen; Thompson, April; Douiri, Abdel; Moxham, John; Hart, Nicholas

    2015-01-01

    Purpose The aim of this study was to investigate feasibility of exercise-based rehabilitation delivered after hospital discharge in patients with intensive care unit?acquired weakness (ICU-AW). Materials and methods Twenty adult patients, mechanically ventilated for more than 48 hours, with ICU-AW diagnosis at ICU discharge were included in a pilot feasibility randomized controlled trial receiving a 16-session exercise-based rehabilitation program. Twenty-one patients without ICU-AW participa...

  12. Gossip Consensus Algorithm Based on Time-Varying Influence Factors and Weakly Connected Graph for Opinion Evolution in Social Networks

    Directory of Open Access Journals (Sweden)

    Lingyun Li

    2013-01-01

    Full Text Available We provide a new gossip algorithm to investigate the problem of opinion consensus with the time-varying influence factors and weakly connected graph among multiple agents. What is more, we discuss not only the effect of the time-varying factors and the randomized topological structure but also the spread of misinformation and communication constrains described by probabilistic quantized communication in the social network. Under the underlying weakly connected graph, we first denote that all opinion states converge to a stochastic consensus almost surely; that is, our algorithm indeed achieves the consensus with probability one. Furthermore, our results show that the mean of all the opinion states converges to the average of the initial states when time-varying influence factors satisfy some conditions. Finally, we give a result about the square mean error between the dynamic opinion states and the benchmark without quantized communication.

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

    Science.gov (United States)

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

    2012-10-02

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

  14. A low dietary cation-anion difference precalving and calcium supplementation postcalving increase plasma calcium but not milk production in a pasture-based system.

    Science.gov (United States)

    Roche, J R; Dalley, D; Moate, P; Grainger, C; Rath, M; O'Mara, F

    2003-08-01

    It was hypothesized that a reduction in the dietary cation-anion difference (DCAD) before calving, combined with an increase in Ca intake after calving, would reduce the incidence of periparturient hypocalcaemia and increase milk production in pasture-based dairy cows. Cows (n = 40) were assigned to one of two DCAD levels before calving (i.e., +7 and +50 mEq/100 g). Each group was then assigned to one of two dietary Ca concentrations after calving (i.e., 1.0 and 0.7%) in a 2 x 2 factorial design. The lower DCAD resulted in a nonrespiratory reduction in systemic pH as indicated by a lower urine pH. This acidosis resulted in an increased concentration of Ca in urine before calving. The lower precalving DCAD helped prevent the decline in blood Ca caused by the onset of lactation, even though blood Ca concentration was lower before calving compared with cows receiving a high DCAD. Supplementation of cows with Ca after calving increased plasma Ca concentration on the day of calving and during the subsequent 14 d. Milk production was not affected by pre- or postcalving treatments.

  15. Prediction of the properties and thermodynamics of formation for energetic nitrogen-rich salts composed of triaminoguanidinium cation and 5-nitroiminotetrazolate-based anions.

    Science.gov (United States)

    Zhu, Weihua; Yan, Qingli; Li, Jinshan; Cheng, Bibo; Shao, Yuling; Xia, Xuelan; Xiao, Heming

    2012-08-15

    Density functional theory and volume-based thermodynamics calculations were performed to study the effects of different substituents and linkages on the densities, heats of formation (HOFs), energetic properties, and thermodynamics of formation for a series of energetic nitrogen-rich salts composed of triaminoguanidinium cation and 5-nitroiminotetrazolate anions. The results show that the -NO(2), -NF(2), or -N(3) group is an effective substituent for increasing the densities of the 5-nitroiminotetrazolate salts, whereas the effects of the bridge groups on the density are coupled with those of the substituents. The substitution of the group -NH(2), -NO(2), -NF(2), -N(3), or the nitrogen bridge is helpful for increasing the HOFs of the salts. The calculated energetic properties indicate that the -NO(2), -NF(2), -N(3), or -N=N- group is an effective structural unit for improving the detonation performance for salts. The thermodynamics of formation of the salts show that all the salts may be synthesized easily by the proposed reactions. The structure-property relationships provide basic information for the molecular design of novel high-energy salts. Copyright © 2012 Wiley Periodicals, Inc.

  16. New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

    KAUST Repository

    Chubar, Natalia

    2011-05-01

    New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H2AsO4- is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220. mg[As]. gdw-1 for the best sample at pH = 7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. © 2011 Elsevier Inc.

  17. Effect of anionic salts in concentrate mixture on some blood and urine minerals, acid-base balance and feed intake of dry pregnant cows on grass silage based feeding with high calcium intake

    Directory of Open Access Journals (Sweden)

    S. TAURIAINEN

    2008-12-01

    Full Text Available The objective was to study the effects of anionic salts in a concentrate mixture on some blood and urine minerals, acid-base balance and intake of Ayrshire cows fed a grass silage based diet. Eighteen nonlactating, pregnant Ayrshire cows were divided randomly into two groups according to their expected calving date. Dietary cation-anion balance (DCAB, calculated as milliequivalents [(Na+ + K+ - (Cl- + S2-] of the two diets was +410 mEq/kg of dietary dry matter (DM in the high DCAB group and +81 mEq/kg of the dietary DM in the low DCAB group, respectively. The DCAB was formulated using NH4Cl, (NH42SO4 and MgCl2 as anionic salts. Cows received grass silage (5.2 kg DM, hay (0.8 kg DM and a concentrate mixture (1.7 kg DM until calving. Both diets were supplemented with 100 g CaCO3 to achieve a high Ca intake (82 g Ca/d. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, the day after calving and 1 week following calving. Current data indicated that it may be difficult to formulate a diet with a negative DCAB, if the K content of grass silage is over 30 g/kg DM. As a result, no increase in blood Ca2+ and a relatively high urinary pH were observed. Furthermore, it may advantageous to increase Mg intakes above current Finnish recommendations when dietary Ca concentrations are high, since 28% of experimental cows experienced hypomagnaesemia at parturition.;

  18. Simultaneous separation of inorganic anions and cations by using anion-exchange and cation-exchange columns connected in tandem in ion chromatography.

    Science.gov (United States)

    Karim, Khairil Juhanni Binti Abd; Jin, Ji-Ye; Takeuchi, Toyohide

    2003-05-02

    Inorganic anions and cations in environmental waters were determined by ion chromatography. Stationary and mobile phases were examined for the simultaneous separation of both anions and cations. Cations detection by UV detection requires a mobile phase with a UV absorbing additive, which indirectly visualizes cations as negative peaks. Simultaneous separation of anions and cations were achieved when using an eluent that consists of inorganic acid with weak basic amino acid as additives. It was convenient to separate both anions and cations by coupling anion-exchange and cation-exchange columns in tandem. The order of the separation columns connected affected the elution profiles. When the eluent comprises of multiple anions and a single cation, the anion-exchange column should be connected in the upper stream, whereas when the eluent comprises multiple cations and a single anion, the cation-exchange column should be connected in the upper stream. Use of switching valves also allowed simultaneous separation of anions and cations in a single chromatographic run. In the present work, operating conditions were optimized for the simultaneous separation of anions and cations.

  19. Dietary cation-anion difference and dietary protein effects on performance and acid-base status of dairy cows in early lactation.

    Science.gov (United States)

    Hu, W; Murphy, M R; Constable, P D; Block, E

    2007-07-01

    Our objective was to examine the effects of dietary cation-anion difference (DCAD) with different concentrations of dietary crude protein (CP) on performance and acid-base status in early lactation cows. Six lactating Holstein cows averaging 44 d in milk were used in a 6 x 6 Latin square design with a 2 x 3 factorial arrangement of treatments: DCAD of -3, 22, or 47 milliequivalents (Na + K - Cl - S)/100 g of dry matter (DM), and 16 or 19% CP on a DM basis. Linear increases with DCAD occurred in DM intake, milk fat percentage, 4% fat-corrected milk production, milk true protein, milk lactose, and milk solids-not-fat. Milk production itself was unaffected by DCAD. Jugular venous blood pH, base excess and HCO3(-) concentration, and urine pH increased, but jugular venous blood Cl- concentration, urine titratable acidity, and net acid excretion decreased linearly with increasing DCAD. An elevated ratio of coccygeal venous plasma essential AA to nonessential AA with increasing DCAD indicated that N metabolism in the rumen was affected, probably resulting in more microbial protein flowing to the small intestine. Cows fed 16% CP had lower urea N in milk than cows fed 19% CP; the same was true for urea N in coccygeal venous plasma and urine. Dry matter intake, milk production, milk composition, and acid-base status did not differ between the 16 and 19% CP treatments. It was concluded that DCAD affected DM intake and performance of dairy cows in early lactation. Feeding 16% dietary CP to cows in early lactation, compared with 19% CP, maintained lactation performance while reducing urea N excretion in milk and urine.

  20. Effect of dietary cation-anion difference and dietary crude protein on milk yield, acid-base chemistry, and rumen fermentation.

    Science.gov (United States)

    Wildman, C D; West, J W; Bernard, J K

    2007-10-01

    Eight primiparous lactating Holstein cows (47 +/- 10 d in milk) fitted with ruminal cannulae were used to determine the effect of dietary cation-anion difference (DCAD) and dietary crude protein (CP) concentration on milk yield and composition, acid-base chemistry, and measures of N metabolism in lactating dairy cows. Treatments were arranged as a 2 x 2 factorial in a randomized complete block design to provide 15 or 17% CP and DCAD of 25 or 50 mEq (Na + K - Cl)/100 g of feed dry matter [15 or 39 mEq (Na + K) - (Cl + S)/100 g of feed dry matter]. High DCAD improved dry matter intake, milk yield, and concentrations of milk fat and protein. An interaction of DCAD and CP was observed for uric acid excretion, an indicator of microbial protein yield. Uric acid excretion was higher for high DCAD than for low DCAD in low CP diets and was similar for low and high DCAD with high CP. Serum bicarbonate concentration, urinary bicarbonate excretion, blood pH, and serum Na were elevated for high DCAD compared with low DCAD. Fractional excretion of Na, K, Cl, and Ca increased for high DCAD. Blood urea N and urinary urea N were greater for high than for low CP diets. No differences due to DCAD were observed for these parameters. Results of this study suggest that, in early lactation cows, blood acid-base chemistry is altered by differences in DCAD that range between the high and low ends of the desired DCAD range. Modifications of acid-base chemistry and the corresponding changes in protein metabolism may allow for more efficient feeding of protein and better nutritional management of the lactating dairy cow.

  1. Photoelectron imaging of cyanovinylidene and cyanoacetylene anions.

    Science.gov (United States)

    Goebbert, Daniel J; Khuseynov, Dmitry; Sanov, Andrei

    2010-02-18

    Negative ions of cyanoacetylene and cyanovinylidene are generated simultaneously via the competing 1,1-H(2)(+) and 1,2-H(2)(+) abstraction channels of O(-) reaction with acrylonitrile. The two stable isomeric forms of the anion, CCHCN(-) and HCCCN(-), are separated by a large (approximately 2 eV) potential energy barrier. Their photodetachment provides access to both the reactant and the product sides of the neutral cyanovinylidene --> cyanoacetylene rearrangement reaction, predicted to involve only a very small barrier. Using photoelectron imaging spectroscopy at 532 and 355 nm, the adiabatic electron affinity of the reactive intermediate :C horizontal lineCHCN (X(1)A'), is determined to be 1.84 +/- 0.01 eV. The photoelectron spectrum of CCHCN(-) exhibits a vibrational progression attributed to the excitation of the CCH bending mode. The observed spectral features are reproduced reasonably well using a Franck-Condon simulation under the parallel-mode approximation. In contrast to unsubstituted acetylene, cyanoacetylene has a stable anionic state, which is adiabatically weakly bound, but has an experimentally determined vertical detachment energy of 1.04 +/- 0.05 eV. This measurement, along with the broad, structureless photoelectron spectrum of HCCCN(-) (with no identifiable origin), reflects the large geometry difference between the w-shaped structure of the anion and the linear equilibrium geometry of HCCCN.

  2. A label-free GR-5DNAzyme sensor for lead ions detection based on nanoporous gold and anionic intercalator.

    Science.gov (United States)

    Zhou, Yaoyu; Zhang, Jiachao; Tang, Lin; Peng, Bo; Zeng, Guangming; Luo, Lin; Gao, Jun; Pang, Ya; Deng, Yaocheng; Zhang, Fengfeng

    2017-04-01

    A label-free electrochemical sensor, based on a classic lead ions (Pb(2+))-dependent GR-5DNAzyme as the catalytic unit, disodium-anthraquinone-2,6-disulfonate (AQDS) as DNA intercalator, and nanoporous gold (NPG) for signal amplification, was designed for sensitive and selective detection of Pb(2+). Firstly, NPG modified electrode surface were employed as a platform for the immobilization of thiolated probe DNA, and then, hybridized with DNAzyme catalytic beacons. The Pb(2+)-induced catalytic reaction makes the substrate strand break at the cleavage sitGe irreversibly, which disturbs the formation of DNA strands. AQDS served as an indicator that intercalated into the base-pairing regions of DNAzyme, resulting in a strong electrochemical signal. In the presence of Pb(2+), the complementary regions were reduced, due to the fracture of the DNA strand, resulting in the release of AQDS. And a decreased current was obtained, corresponding to Pb(2+) concentration. Taking advantage of the amplification effect of NPG electrode for increasing the reaction sites of thiol modified capture probe, the proposed electrochemical biosensor could detect Pb(2+) quantitatively, in the range of 1-120nM, with a limit of detection as low as 0.02nM, which is much lower than the maximum contamination level for Pb(2+) in drinking water defined by the U.S. Environmental Protection Agency. The electrochemical sensor was also used to detect Pb(2+) from real water samples, and the results showed excellent agreement with the values determined by inductively coupled plasma mass spectroscopy. This biosensor showed a promising potential for on-site detecting Pb(2+) in aqueous environment. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  4. Ionic liquids and oligomer electrolytes based on the B(CN)4(-) anion; ion association, physical and electrochemical properties.

    Science.gov (United States)

    Scheers, Johan; Pitawala, Jagath; Thebault, Frederic; Kim, Jae-Kwang; Ahn, Jou-Hyeon; Matic, Aleksandar; Johansson, Patrik; Jacobsson, Per

    2011-09-07

    The role of B(CN)(4)(-) (Bison) as a component of battery electrolytes is addressed by investigating the ionic conductivity and phase behaviour of ionic liquids (ILs), ion association mechanisms, and the electrochemical stability and cycling properties of LiBison based electrochemical cells. For C(4)mpyrBison and C(2)mimBison ILs, and mixtures thereof, high ionic conductivities (3.4 ≤σ(ion)≤ 18 mS cm(-1)) are measured, which together with the glass transition temperatures (-80 ≤T(g)≤-76 °C) are found to shift systematically for most compositions. Unfortunately, poor solubility of LiBison in these ILs hinders their use as solvents for lithium salts, although good NaBison solubility offers an alternative application in Na(+) conducting electrolytes. The poor IL solubility of LiBison is predicted to be a result of a preferred monodentate ion association, according to first principles modelling, supported by Raman spectroscopy. The solubility is much improved in strongly Li(+) coordinating oligomers, for example polyethylene glycol dimethyl ether (PEGDME), with the practical performance tested in electrochemical cells. The electrolyte is found to be stable in Li/LiFePO(4) coin cells up to 4 V vs. Li and shows promising cycling performance, with a capacity retention of 99% over 22 cycles. This journal is © the Owner Societies 2011

  5. Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Shiraishi, Takahiro [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Suga, Mikio [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Center for Frontier Medical Engineering, Chiba University (Japan); Obata, Takayuki [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Ito, Hiroshi; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan)

    2014-07-29

    In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

  6. Colorimetric anion sensors based on positional effect of nitro group for recognition of biologically relevant anions in organic and aqueous medium, insight real-life application and DFT studies

    Science.gov (United States)

    Singh, Archana; Sahoo, Suban K.; Trivedi, Darshak R.

    2018-01-01

    A new six colorimetric receptors A1-A6 were designed and synthesized, characterized by typical common spectroscopic techniques like FT-IR, UV-Visible, 1H NMR, 13C NMR and ESI-MS. The receptor A1 and A2 exhibit a significant naked-eye response towards F- and AcO- ions in DMSO. Due to presences of the NO2 group at para and ortho position with extended π-conjugation of naphthyl group carrying sbnd OH as a binding site. Compared to receptor A2, A1 is extremely capable of detecting F- and AcO- ions present in the form of sodium salts in an aqueous medium. This is owed to the occurrence of sbnd NO2 group at para position induced in increasing the acidity of sbnd OH proton. Consequently, it easily gets deprotonated in aqueous media. The detection limit of receptor A1 was turned out to be 0.40 and 0.35 ppm for F- and AcO- ions which is beneath WHO permission level (1.0 ppm). Receptor A1 shows a solitary property of solvatochromism in different aprotic solvents in presence of AcO- ion. Receptor A1 depicts high selectivity towards AcO- ion in DMSO: HEPES buffer (9:1, v/v). Receptor A1 proved itself for real life application by detecting anion in solution and solid state. The binding mechanism of receptor A1 with AcO- and F- ions was monitored from 1HNMR titration and DFT study.

  7. Effect of dietary cation-anion difference on ruminal metabolism, total apparent digestibility, blood and renal acid-base regulation in lactating dairy cows.

    Science.gov (United States)

    Martins, C M M R; Arcari, M A; Welter, K C; Gonçalves, J L; Santos, M V

    2016-01-01

    The present study aimed to evaluate the effect of dietary cation-anion difference (DCAD) on ruminal fermentation, total apparent digestibility, blood and renal metabolism of lactating dairy cows. Sixteen Holstein cows were distributed in four contemporary 4×4 Latin Square designs, which consisted of four periods of 21 days and four treatments according to DCAD: +290; +192; +98 and -71 milliequivalent (mEq)/kg dry matter (DM). Ruminal pH and concentrations of acetic and butyric acid increased linearly according to the increase of DCAD. Similarly, NDF total apparent digestibility linearly increased by 6.38% when DCAD increased from -71 to 290 mEq/kg DM [Y=65.90 (SE=2.37)+0.0167 (SE=0.0068)×DCAD (mEq/kg DM)]. Blood pH was also increased according to DCAD, which resulted in reduction of serum concentrations of Na, K and ionic calcium (iCa). To maintain the blood acid-base homeostasis, renal metabolism played an important role in controlling serum concentrations of Na and K, since the Na and K urinary excretion increased linearly by 89.69% and 46.06%, respectively, from -71 to 290 mEq/kg DM. Changes in acid-base balance of biological fluids may directly affect the mineral composition of milk, as milk concentrations of Na, K, iCa and chlorides were reduced according to blood pH increased. Thus, it can be concluded that the increase of DCAD raises the pH of ruminal fluid, NDF total apparent digestibility, and blood pH, and decreases the milk concentration of cationic minerals, as well as the efficiency of Na utilization to milk production.

  8. Homolog-focused profiling of ginsenosides based on the integration of step-wise formate anion-to-deprotonated ion transition screening and scheduled multiple reaction monitoring.

    Science.gov (United States)

    Song, Yuelin; Zhang, Na; Shi, Shepo; Li, Jun; Zhao, Yunfang; Zhang, Qian; Jiang, Yong; Tu, Pengfei

    2015-08-07

    Homolog-focused profiling is a favored option to bridge targeted metabolomics toward non-targeted metabolomics. In current study, an attempt was made for the large-scale ginsenoside-specific analysis in ginseng (G) and American ginseng (AG). When formic acid (0.1%, v/v) was introduced as the mobile phase additive, formate anion-to-deprotonated ion transitions ([M+HCOO](-)>[M-H](-)) with an optimal collision energy (-32eV) could result in satisfactory responses for ginsenosides. Therefore, a step-wise multiple reaction monitoring (MRM)-based method employing [M+HCOO](-)>[M-H](-) ion pairs was constructed to screen ginsenosides among 501-1250u (for Q1) with a step-size of 2u, and MRM also served as a survey experiment to trigger enhanced product ion scans for MS(2) spectrum acquisition on a hybrid triple quadrupole-linear ion trap mass spectrometer; then, the identification of those observed ginsenosides was achieved on the basis of the well-defined mass cracking patterns for ginsenosides; afterwards, scheduled MRM was introduced for large-scale relatively quantitative analysis of all detected ginsenosides. Finally, comparative metabolomics were performed to differentiate G, AG, and their processed products. Method validation was carried out using thirteen authentic compounds. A total of 221 ginsenosides, among which 185 ones were annotated, were observed and relatively quantitated. All crude materials were obviously classified into groups I-III. Above all, the MRM-based homolog-focused profiling of ginsenosides could be used as a reliable tool to gain an in-depth view for ginsenoside-enriched herbal products. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Treatment of Perchlorate-Contaminated Groundwater Using Highly-Selective, Regenerable Anion-Exchange Resins at Edwards Air Force Base

    Energy Technology Data Exchange (ETDEWEB)

    Gu, B.

    2003-05-30

    Selective ion exchange is one of the most effective treatment technologies for removing low levels of perchlorate (ClO{sub 4}{sup -}) from contaminated water because of its high efficiency without adverse impacts on the water quality caused by adding or removing any chemicals or nutrients. This report summarizes both the laboratory and a field pilot-scale studies to determine the ability and efficiency of the bifunctional synthetic resins to remove ClO{sub 4}{sup -} from the contaminated groundwater at the Edwards Air Force Base in California. Regeneration of the resins after groundwater treatment was also evaluated using the FeCl{sub 3}-HCl regeneration technique recently developed at Oak Ridge National Laboratory. On the basis of this study, the bifunctional resin, D-3696 was found to be highly selective toward ClO{sub 4}{sup -} and performed much better than one of the best commercial nitrate-selective resins (Purolite A-520E) and more than an order of magnitude better than the Purolite A-500 resin (with a relatively low selectivity). At an influent concentration of {approx} 450 {micro}g/L ClO{sub 4}{sup -} in groundwater, the bifunctional resin bed treated {approx} 40,000 empty bed volumes of groundwater before a significant breakthrough of ClO{sub 4}{sup -} occurred. The presence of relatively high concentrations of chloride and sulfate in site groundwater did not appear to affect the ability of the bifunctional resin to remove ClO{sub 4}{sup -}. However, the presence of high iron or iron oxyhydroxides and/or biomass in groundwater caused a significant fouling of the resin beds and greatly influenced the effectiveness in regenerating the resins sorbed with ClO{sub 4}{sup -}. Under such circumstances, a prefilter ({approx} 0.5-1 {micro}m) was found to be necessary to remove these particulates and to reduce the risk of fouling of the resin beds. Without significant fouling, the resin bed could be effectively regenerated by the FeCl{sub 3} displacement technique

  10. Tuning the electronic environment of the anion by using binary ionic liquid mixtures

    Science.gov (United States)

    Men, Shuang; Licence, Peter

    2017-08-01

    The electronic environment of the anion is tuned by using binary ionic liquid mixtures employing a common anion and two cations with large difference in acidity. X-ray photoelectron spectroscopy is used to monitor the change of the electronic environment of the anion by measuring the binding energy of elements present in the anion. It is found that due to the large difference in acidity of the two cations, noticeable shifts can be observed for all anion-based components, no matter how basic the anion is.

  11. High-performance liquid chromatography - Ultraviolet method for the determination of total specific migration of nine ultraviolet absorbers in food simulants based on 1,1,3,3-Tetramethylguanidine and organic phase anion exchange solid phase extraction to remove glyceride.

    Science.gov (United States)

    Wang, Jianling; Xiao, Xiaofeng; Chen, Tong; Liu, Tingfei; Tao, Huaming; He, Jun

    2016-06-17

    The glyceride in oil food simulant usually causes serious interferences to target analytes and leads to failure of the normal function of the RP-HPLC column. In this work, a convenient HPLC-UV method for the determination of the total specific migration of nine ultraviolet (UV) absorbers in food simulants was developed based on 1,1,3,3-tetramethylguanidine (TMG) and organic phase anion exchange (OPAE) SPE to efficiently remove glyceride in olive oil simulant. In contrast to the normal ion exchange carried out in an aqueous solution or aqueous phase environment, the OPAE SPE was performed in the organic phase environments, and the time-consuming and challenging extraction of the nine UV absorbers from vegetable oil with aqueous solution could be readily omitted. The method was proved to have good linearity (r≥0.99992), precision (intra-day RSD≤3.3%), and accuracy(91.0%≤recoveries≤107%); furthermore, the lower limit of quantifications (0.05-0.2mg/kg) in five types of food simulants(10% ethanol, 3% acetic acid, 20% ethanol, 50% ethanol and olive oil) was observed. The method was found to be well suited for quantitative determination of the total specific migration of the nine UV absorbers both in aqueous and vegetable oil simulant according to Commission Regulation (EU) No. 10/2011. Migration levels of the nine UV absorbers were determined in 31 plastic samples, and UV-24, UV-531, HHBP and UV-326 were frequently detected, especially in olive oil simulant for UV-326 in PE samples. In addition, the OPAE SPE procedure was also been applied to efficiently enrich or purify seven antioxidants in olive oil simulant. Results indicate that this procedure will have more extensive applications in the enriching or purification of the extremely weak acidic compounds with phenol hydroxyl group that are relatively stable in TMG n-hexane solution and that can be barely extracted from vegetable oil. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Precision metrology using weak measurements.

    Science.gov (United States)

    Zhang, Lijian; Datta, Animesh; Walmsley, Ian A

    2015-05-29

    Weak values and measurements have been proposed as a means to achieve dramatic enhancements in metrology based on the greatly increased range of possible measurement outcomes. Unfortunately, the very large values of measurement outcomes occur with highly suppressed probabilities. This raises three vital questions in weak-measurement-based metrology. Namely, (Q1) Does postselection enhance the measurement precision? (Q2) Does weak measurement offer better precision than strong measurement? (Q3) Is it possible to beat the standard quantum limit or to achieve the Heisenberg limit with weak measurement using only classical resources? We analyze these questions for two prototypical, and generic, measurement protocols and show that while the answers to the first two questions are negative for both protocols, the answer to the last is affirmative for measurements with phase-space interactions, and negative for configuration space interactions. Our results, particularly the ability of weak measurements to perform at par with strong measurements in some cases, are instructive for the design of weak-measurement-based protocols for quantum metrology.

  13. SHORT COMMUNICATION POLYPROPYLENE BASED ANION ...

    African Journals Online (AJOL)

    Preferred Customer

    Bull. Chem. Soc. Ethiop. 2011, 25(2). 296 were injected with 10 μL samples. Tungsten coated graphite tubes were used throughout. The instrumental parameters are summarized in Table 1. Table 1. Temperature program for the graphite furnace. Step. Start temperature (oC) End temperature (oC) Time (s) Ar flow (mL·min-1).

  14. The Influence of Anion Shape on the Electrical Double Layer Microstructure and Capacitance of Ionic Liquids-Based Supercapacitors by Molecular Simulations

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2017-02-01

    Full Text Available Room-temperature ionic liquids (RTILs are an emerging class of electrolytes for supercapacitors. In this work, we investigate the effects of different supercapacitor models and anion shape on the electrical double layers (EDLs of two different RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonylimide ([Emim][Tf2N] and 1-ethyl-3-methylimidazolium 2-(cyanopyrrolide ([Emim][CNPyr] by molecular dynamics (MD simulation. The EDL microstructure is represented by number densities of cations and anions, and the potential drop near neutral and charged electrodes reveal that the supercapacitor model with a single electrode has the same EDL structure as the model with two opposite electrodes. Nevertheless, the employment of the one-electrode model without tuning the bulk density of RTILs is more time-saving in contrast to the two-electrode one. With the one-electrode model, our simulation demonstrated that the shapes of anions significantly imposed effects on the microstructure of EDLs. The EDL differential capacitance vs. potential (C-V curves of [Emim][CNPyr] electrolyte exhibit higher differential capacitance at positive potentials. The modeling study provides microscopic insight into the EDLs structure of RTILs with different anion shapes.

  15. Investigating the Structure and Reactivity of Azolyl-Based Copper(I)–NHC Complexes: The Role of the Anionic Ligand

    KAUST Repository

    Trose, Michael

    2017-11-01

    A family of copper(I)–NHC azolyl complexes was synthesized and deployed in the hydrosilylation of dicyclo-hexylketone to probe the role of the anionic ligand on catalytic performance. The azolyl ligand is shown to have a crucial role in catalytic activity without the need for additives, and this at very low catalyst loading.

  16. A new type of polyhedron-based metal-organic frameworks with interpenetrating cationic and anionic nets demonstrating ion exchange, adsorption and luminescent properties.

    Science.gov (United States)

    Zhang, Zheng-Jie; Shi, Wei; Niu, Zheng; Li, Huan-Huan; Zhao, Bin; Cheng, Peng; Liao, Dai-Zheng; Yan, Shi-Ping

    2011-06-14

    An interesting new MOF, built with interpenetrating cationic (MOF-A(+)) and anionic (MOF-B(-)) nets that do not require counter ions to balance charge, together with an architectural strategy focused on the use of MOPs as nodes and MOCs as spacers for the generation of 3D frameworks, is reported. This journal is © The Royal Society of Chemistry 2011

  17. Changes in microstructure of two ammonium-based protic ionic liquids proved by in situ variable-temperature 1 H NMR spectroscopy: influence of anion.

    Science.gov (United States)

    Tang, Xiaochen; Xu, Yingjie; Zhu, Xiao; Lu, Yueqing

    2017-04-22

    In this work, changes in microstructure of two protic ionic liquids (PILs), namely n-butylammonium acetate (N4Ac) and n-butylammonium nitrate (N4NO3 ), are proved by in situ variable-temperature 1 H NMR spectroscopy at the temperature range from 25 to 115 °C, and the influence of the nature of anion is discussed accordingly. The results demonstrate that 1 H NMR chemical shifts of alkyl protons of both N4Ac and N4NO3 are almost not changed with the increasing of temperature, due to the absence of hydrogen bond interaction between alkyl protons with anions. Whereas those of + N-H of cation decrease linearly with the temperature increasing, indicating that the hydrogen bond interaction between + N-H and anion weakens gradually. In addition, the strength of hydrogen bond interaction between + N-H and NO3- is stronger than that between + N-H and Ac- , suggesting that anions have a significant influence on microstructure due to the acidity of a Brønsted acid. Consequently, the proton transfer from cation to anion is much easier in N4Ac compared to N4NO3 . Further analyses of 1 H NMR chemical shifts of + N-H in N4Ac at the temperature range from 100 to 115 °C suggest that the splitting of + N-H peak may be attributed to obvious evidence of the existence of the proton transfer from + N-H to Ac- , which leads to dissociate the contact ion-pair in N4Ac to form the neutral ion-pair 'molecule'. The results will help us to extensively understand the behavior of proton transfer and offer us some valuable information for the design of PILs. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  18. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Unknown

    trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange properties together with surface basicity making them materials of importance ...

  19. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

  20. In vitro dissolution methodology, mini-Gastrointestinal Simulator (mGIS), predicts better in vivo dissolution of a weak base drug, dasatinib.

    Science.gov (United States)

    Tsume, Yasuhiro; Takeuchi, Susumu; Matsui, Kazuki; Amidon, Gregory E; Amidon, Gordon L

    2015-08-30

    USP apparatus I and II are gold standard methodologies for determining the in vitro dissolution profiles of test drugs. However, it is difficult to use in vitro dissolution results to predict in vivo dissolution, particularly the pH-dependent solubility of weak acid and base drugs, because the USP apparatus contains one vessel with a fixed pH for the test drug, limiting insight into in vivo drug dissolution of weak acid and weak base drugs. This discrepancy underscores the need to develop new in vitro dissolution methodology that better predicts in vivo response to assure the therapeutic efficacy and safety of oral drug products. Thus, the development of the in vivo predictive dissolution (IPD) methodology is necessitated. The major goals of in vitro dissolution are to ensure the performance of oral drug products and the support of drug formulation design, including bioequivalence (BE). Orally administered anticancer drugs, such as dasatinib and erlotinib (tyrosine kinase inhibitors), are used to treat various types of cancer. These drugs are weak bases that exhibit pH-dependent and high solubility in the acidic stomach and low solubility in the small intestine (>pH 6.0). Therefore, these drugs supersaturate and/or precipitate when they move from the stomach to the small intestine. Also of importance, gastric acidity for cancer patients may be altered with aging (reduction of gastric fluid secretion) and/or co-administration of acid-reducing agents. These may result in changes to the dissolution profiles of weak base and the reduction of drug absorption and efficacy. In vitro dissolution methodologies that assess the impact of these physiological changes in the GI condition are expected to better predict in vivo dissolution of oral medications for patients and, hence, better assess efficacy, toxicity and safety concerns. The objective of this present study is to determine the initial conditions for a mini-Gastrointestinal Simulator (mGIS) to assess in vivo

  1. A new approach for power quality improvement of DFIG based wind farms connected to weak utility grid

    Directory of Open Access Journals (Sweden)

    Hossein Mahvash

    2017-09-01

    Full Text Available Most of power quality problems for grid connected doubly fed induction generators (DFIGs with wind turbine include flicker, variations of voltage RMS profile, and injected harmonics due to switching in DFIG converters. Flicker phenomenon is the most important problem in wind power systems. This paper described an effective method for mitigating flicker emission and power quality improvement for a fairly weak grid connected to a wind farm with DFIGs. The method was applied in the rotor side converter (RSC of the DFIG to control the output reactive power. q axis reference current was directly derived according to the mathematical relation between rotor q axis current and DFIG output reactive power without using PI controller. To extract the reference reactive power, the stator voltage control loop with the droop coefficient was proposed to regulate the grid voltage level in each operational condition. The DFIG output active power was separately controlled in d axis considering the stator voltage orientation control (SVOC. Different simulations were carried out on the test system and the flicker short term severity index (Pst was calculated for each case study using the discrete flickermeter model according to IEC 61400 standard. The obtained results validated flicker mitigation and power quality enhancement for the grid.

  2. Appoach to realizing weak hydroacoustic beaconing signal based on DSP%一种基于DSP的声信标弱信号提取方法

    Institute of Scientific and Technical Information of China (English)

    李笑媛; 程晶; 那健

    2014-01-01

    介绍一种基于DSP处理模块实现声信标弱信号提取的方法。针对声信标的性能参数及其具体应用环境,采用一种在加性白噪声环境下能够使信号的输出信噪比达到最大的匹配滤波方法,并将其在DSP处理模块上实现,最终将检测结果以音频和视频的形式输出。经过实际应用测试,该方法易于实现,实时性好,在复杂的海洋背景噪声下可以较好提高声信标的作用距离。%This paper introduces a method to realize weak hydroacoustic beaconing signal detecting base on DSP. According to the capability parameters of the hydroacoustic beaconing that the subject have adopted and the application of the hydroacoustic beaconing to the specific environment, also because the matching filter is the best filter means in the condition of additive white noise, it can make the SNR of the output signal to maximize, so this paper adopted the matching filter method, and at last the subject realized weak hydroacoustic beaconing signal detecting on DSP module. After real testing, the system which is good for weak hydroacoustic beaconing signal detecting can run real-time and realize easily. After sea trials, the system using the method can quickly find the target when hydroacoustic beaconing in a long distance. The sea trials shows the method can improve detection distance and easy to use in the areas of the weak hydroacoustic beaconing signal detecting.

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

    Science.gov (United States)

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

    2017-10-01

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  5. Effects of dietary cation-anion difference on ruminal metabolism and blood acid-base regulation in dairy cows receiving 2 contrasting levels of concentrate in diets.

    Science.gov (United States)

    Apper-Bossard, E; Faverdin, P; Meschy, F; Peyraud, J L

    2010-09-01

    Dietary cation-anion difference [DCAD=Na+K-Cl in mEq/kg of dry matter (DM)] increases DM intake (DMI) in cows fed diets containing rapidly degraded starch. Increased DMI of diets containing rapidly degraded starch could potentially exacerbate subacute acidosis. The objective of this study was to determine metabolic effects of increasing DCAD in low and high starch diets. Six cannulated Holstein cows were blocked into 2 groups of 3 cows and assigned to two 3 x 3 Latin squares in a split-plot design. Each group received a level of concentrate at either 20 or 40% on a DM basis. The diet containing 20% concentrate supplied 4% rapidly degraded starch, whereas the diet containing 40% concentrate supplied 22% rapidly degraded starch. Diets in each square were formulated to provide a DCAD of 0, 150, or 300 mEq/kg of DM. The 3 values were obtained by manipulating Na and Cl contents. Increasing the proportion of rapidly degraded starch decreased rumen pH and the acetate to propionate ratio but did not affect digestibility, blood acid-base status, pH of urine, and strong ion excretion. Increasing DCAD increased DMI, the effect being higher when the cows were fed the 40% concentrate diet. Increasing DCAD did not affect mean ruminal pH, molar proportion of VFA, and fiber digestibility; reduced the range of rumen pH decrease during the meal in cows fed the 40% concentrate diet; and strongly increased blood pH and blood HCO3 concentration. Increasing DCAD increased urine pH and modified the urinary excretion of minerals. With low DCAD, 70% of Cl and only 16% of Na were excreted in urine whereas with high DCAD, 33% of Cl and 53% of Na were excreted. These results suggest that DMI of cows fed diets rich in rapidly degraded starch and low DCAD was limited to maintain the blood pH in a physiological range. Increasing DCAD allowed the cows to increase DMI because of the ability of positive DCAD to maintain blood acid-base status. A localized rumen buffering effect could not be

  6. The use of a bivalent counter anion to control the effective mobility of the hydrogen ion constituent in cationic isotachophoresis.

    Science.gov (United States)

    Sudor, J; Stránský, Z; Chmela, Z; Bocek, P

    1988-12-01

    The use of a bivalent counter anion for cationic isotachophoresis was studied both theoretically and experimentally. A mathematical model was proposed and solved to give the effective mobility of the hydrogen ion constituent, uH,H, in the respective electrolyte systems. The theoretical values agreed well with the experimental data in a series of electrolyte systems. The dependence of uH,H on such parameters as pH of the leading electrolyte, ionic mobilities of leading and counter ions, and dissociation constants was calculated and discussed. A bivalent counter anion will prove useful for the separation of low mobility cations and weak bases, as shown for the separation of substituted anilines in a succinate electrolyte system.

  7. Double salt ionic liquids based on 1-ethyl-3-methylimidazolium acetate and hydroxyl-functionalized ammonium acetates: strong effects of weak interactions.

    Science.gov (United States)

    Pereira, Jorge F B; Barber, Patrick S; Kelley, Steven P; Berton, Paula; Rogers, Robin D

    2017-10-11

    The properties of double salt ionic liquids based on solutions of cholinium acetate ([Ch][OAc]), ethanolammonium acetate ([NH 3 (CH 2 ) 2 OH][OAc]), hydroxylammonium acetate ([NH 3 OH][OAc]), ethylammonium acetate ([NH 3 CH 2 CH 3 ][OAc]), and tetramethylammonium acetate ([N(CH 3 ) 4 ][OAc]) in 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]) were investigated by NMR spectroscopy and X-ray crystallography. Through mixture preparation, the solubility of [N(CH 3 ) 4 ][OAc] is the lowest, and [Ch][OAc] shows a 3-fold lower solubility than the other hydroxylated ammonium acetate-based salts in [C 2 mim][OAc] at room temperature. NMR and X-ray crystallographic studies of the pure salts suggest that the molecular-level mechanisms governing such miscibility differences are related to the weaker interactions between the -NH 3 groups and [OAc] - , even though three of these salts possess the same strong 1 : 1 hydrogen bonds between the cation -OH group and the [OAc] - ion. The formation of polyionic clusters between the anion and those cations with unsatisfied hydrogen bond donors seems to be a new tool by which the solubility of these salts in [C 2 mim][OAc] can be controlled.

  8. Assessment of Bioequivalence of Weak Base Formulations Under Various Dosing Conditions Using Physiologically Based Pharmacokinetic Simulations in Virtual Populations. Case Examples: Ketoconazole and Posaconazole.

    Science.gov (United States)

    Cristofoletti, Rodrigo; Patel, Nikunjkumar; Dressman, Jennifer B

    2017-02-01

    Postabsorptive factors which can affect systemic drug exposure are assumed to be dependent on the active pharmaceutical ingredient (API), and thus independent of formulation. In contrast, preabsorptive factors, for example, hypochlorhydria, might affect systemic exposure in both an API and a formulation-dependent way. The aim of this study was to evaluate whether the oral absorption of 2 poorly soluble, weakly basic APIs, ketoconazole (KETO) and posaconazole (POSA), would be equally sensitive to changes in dissolution rate under the following dosing conditions-coadministration with water, with food, with carbonated drinks, and in drug-induced hypochlorhydria. The systems-components of validated absorption and PBPK models for KETO and POSA were modified to simulate the above-mentioned clinical scenarios. Virtual bioequivalence studies were then carried out to investigate whether formulation effects on the plasma profile vary with the dosing conditions. The slow precipitation of KETO upon reaching the upper part of the small intestine renders its absorption more sensitive to the completeness of gastric dissolution and thus to the gastric environment than POSA, which is subject to extensive precipitation in response to a pH shift. The virtual bioequivalence studies showed that hypothetical test and reference formulations containing KETO would be bioequivalent only if the microenvironment in the stomach enables complete gastric dissolution. We conclude that physiologically based pharmacokinetic modeling and simulation has excellent potential to address issues close to bedside such as optimizing dosing conditions. By studying virtual populations adapted to various clinical situations, clinical strategies to reduce therapeutic failures can be identified. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. Biological activity of palladium(II) and platinum(II) complexes of the acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate and the X-ray crystal structure of the [Pd(asme)2] (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) complex.

    Science.gov (United States)

    Akbar Ali, Mohammad; Mirza, Aminul Huq; Butcher, Raymond J; Tarafder, M T H; Keat, Tan Boon; Ali, A Manaf

    2002-11-25

    Palladium(II) and platinum(II) complexes of general empirical formula, [M(NS)(2)] (NS=uninegatively charged acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate; M=Pt(II) and Pd(II)) have been prepared and characterized by a variety of physicochemical techniques. Based on conductance, IR and electronic spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(asme)(2)] complex (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted cis-square planar structure with the ligands coordinated to the palladium(II) ions as uninegatively charged bidentate NS chelating agents via the azomethine nitrogen and the mercaptide sulfur atoms. The distortion from a regular square-planar geometry is attributed to the restricted bite angles of the ligands. Antimicrobial tests indicate that the Schiff bases exhibit strong activities against the pathogenic bacteria, Bacillus subtilis (mutant defective DNA repair), methicillin-resistant Staphylococcus aureus, B. subtilis (wild type) and Pseudomonas aeruginosa and the fungi, Candida albicans (CA), Candida lypotica (2075), Saccharomyces cerevisiae (20341) and Aspergillus ochraceous (398)-the activities exhibited by these compounds being greater than that of the standard antibacterial and antifungal drugs, streptomycin and nystatin, respectively. The palladium(II) and platinum(II) complexes are inactive against most of these organisms but, the microbe, Pseudomonas aeruginosa shows strong sensitivity to the platinum(II) complexes. Screening of the compounds for their cytotoxicities against T-lymphoblastic leukemia cancer cells has shown that the acetone Schiff base of S-methyldithiocarbazate (Hasme) exhibits a very weak activity, whereas the S-benzyl derivative (Hasbz) is inactive. However, the palladium(II) complexes exhibit strong cytotoxicities against this cancer; their

  10. Potentiometric investigation of acid dissociation and anionic homoconjugation equilibria of substituted phenols in dimethyl sulfoxide[Substituted phenols; Acid-base equilibria; Dimethyl sulfoxide (DMSO); Potentiometry

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, Malgorzata; Kozak, Anna; Makowski, Mariusz; Chmurzynski, Lech. E-mail: lech@chemik.chem.univ.gda.pl

    2003-10-01

    Standard acidity constants, K{sub a}{sup DMSO} (HA), expressed as pK{sub a}{sup DMSO} (HA) values, and anionic homoconjugation constants, K{sup DMSO}{sub AHA{sup -}}, (in the form of lg K{sup DMSO}{sub AHA{sup -}} values) have been determined for 11 substituted phenol-phenolate systems a polar protophilic aprotic solvent, dimethyl sulfoxide (DMSO) with a potentiometric titration. A linear relationship has been determined between lg K{sup DMSO}{sub AHA{sup -}} and pK{sub a}{sup DMSO} (HA). The tendency towards anionic homoconjugation in these systems increases with increasing pK{sub a}{sup DMSO} (HA) that is with declining phenol acidity. The pK{sub a}{sup DMSO} (HA) are correlated with both pK{sub a}{sup W} (HA) water and other polar non-aqeous solvents.

  11. A quinoline-based Cu2+ ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells.

    Science.gov (United States)

    Dai, Yanpeng; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xu, Kuoxi; Pang, Xiaobin

    2017-08-05

    A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2+ ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2+ ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu2+ to probe QP was found to be 2.12×104M-1. Further, the Cu2+ ensemble of probe QP was found to respond H2PO4- and HPO42- among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2+ cation and H2PO4- and HPO42- anions in living cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. A quinoline-based Cu2 + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

    Science.gov (United States)

    Dai, Yanpeng; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xu, Kuoxi; Pang, Xiaobin

    2017-08-01

    A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2 + ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2 + ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu2 + to probe QP was found to be 2.12 × 104 M- 1. Further, the Cu2 + ensemble of probe QP was found to respond H2PO4- and HPO42 - among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2 + cation and H2PO4- and HPO42 - anions in living cells.

  13. Analysis of Water Barrier, Mechanical and Thermal Properties of Nanocoposites Based on Cassava Starch and Natural Clay or Modified by Anionic Exchange

    OpenAIRE

    Monteiro,Mayra Kerolly Sales; Oliveira,Victor Rafael Leal de; Santos,Francisco Klebson Gomes dos; Leite,Ricardo Henrique de Lima; Aroucha,Edna Maria Mendes; Silva,Rayane Ricardo da; Silva,Karyn Nathallye de Oliveira

    2017-01-01

    Biopolymer films have several industrial applications because they are environmentally sustainable. Cassava starch is a biopolymer that is easily available, but has limitations: it is hydrophilic, poorly resistant and degradable. The improvement of these properties was proposed in this research from the use of bentonite clay (BT) as a filling material. The compatibilization of this in the polymer matrix was obtained by ion exchange with an organic anionic surfactant. The formation of intercal...

  14. Hip abduction weakness in elite junior footballers is common but easy to correct quickly: a prospective sports team cohort based study

    Directory of Open Access Journals (Sweden)

    Osborne Hamish R

    2012-10-01

    Full Text Available Abstract Background Hip abduction weakness has never been documented on a population basis as a common finding in a healthy group of athletes and would not normally be found in an elite adolescent athlete. This study aimed to show that hip abduction weakness not only occurs in this group but also is common and easy to correct with an unsupervised home based program. Methods A prospective sports team cohort based study was performed with thirty elite adolescent under-17 Australian Rules Footballers in the Australian Institute of Sport/Australian Football League Under-17 training academy. The players had their hip abduction performance assessed and were then instructed in a hip abduction muscle training exercise. This was performed on a daily basis for two months and then they were reassessed. Results The results showed 14 of 28 athletes who completed the protocol had marked weakness or a side-to-side difference of more than 25% at baseline. Two months later ten players recorded an improvement of ≥ 80% in their recorded scores. The mean muscle performance on the right side improved from 151 Newton (N to 202 N (p Conclusions The baseline values show widespread profound deficiencies in hip abduction performance not previously reported. Very large performance increases can be achieved, unsupervised, in a short period of time to potentially allow large clinically significant gains. This assessment should be an integral part of preparticipation screening and assessed in those with lower limb injuries. This particular exercise should be used clinically and more research is needed to determine its injury prevention and performance enhancement implications.

  15. What constitutes evidence-based coaching?: A two-by-two framework for distinguishing strong from weak evidence for coaching

    National Research Council Canada - National Science Library

    Grant, Anthony M

    2016-01-01

    .... At the same time there has been considerable interest in the development of evidence-based approaches to coaching, and many coaching practitioners have incorporated the phrase into their terms...

  16. Effects of S-adenosylmethionine decarboxylase, polyamines, amino acids, and weak bases (amines and ammonia) on development and ribosomal RNA synthesis in Xenopus embryos.

    Science.gov (United States)

    Shiokawa, Koichiro; Aso, Mai; Kondo, Takeshi; Takai, Jun-Ichi; Yoshida, Junki; Mishina, Takamichi; Fuchimukai, Kota; Ogasawara, Tsukasa; Kariya, Taro; Tashiro, Kosuke; Igarashi, Kazuei

    2010-02-01

    We have been studying control mechanisms of gene expression in early embryogenesis in a South African clawed toad Xenopus laevis, especially during the period of midblastula transition (MBT), or the transition from the phase of active cell division (cleavage stage) to the phase of extensive morphogenesis (post-blastular stages). We first found that ribosomal RNA synthesis is initiated shortly after MBT in Xenopus embryos and those weak bases, such as amines and ammonium ion, selectively inhibit the initiation and subsequent activation of rRNA synthesis. We then found that rapidly labeled heterogeneous mRNA-like RNA is synthesized in embryos at pre-MBT stage. We then performed cloning and expression studies of several genes, such as those for activin receptors, follistatin and aldolases, and then reached the studies of S-adenosylmethionine decarboxylase (SAMDC), a key enzyme in polyamine metabolism. Here, we cloned a Xenopus SAMDC cDNA and performed experiments to overexpress the in vitro-synthesized SAMDC mRNA in Xenopus early embryos, and found that the maternally preset program of apoptosis occurs in cleavage stage embryos, which is executed when embryos reach the stage of MBT. In the present article, we first summarize results on SAMDC and the maternal program of apoptosis, and then describe our studies on small-molecular-weight substances like polyamines, amino acids, and amines in Xenopus embryos. Finally, we summarize our studies on weak bases, especially on ammonium ion, as the specific inhibitor of ribosomal RNA synthesis in Xenopus embryonic cells.

  17. Design of tablets for the delayed and complete release of poorly water-soluble weak base drugs using SBE7M-β-CD as a solubilizing agent.

    Science.gov (United States)

    Rao, Venkatramana M; Zannou, Erika A; Stella, Valentino J

    2011-04-01

    The challenge of designing a delayed-release oral dosage form is significantly increased when the drug substance is poorly water soluble. This manuscript describes the design and characterization of a novel controlled-release film-coated tablet for the pH-triggered delayed and complete release of poorly water-soluble weak base drugs. Delivery of weak bases is specifically highlighted with the use of dipyridamole and prazosin as model compounds. Tailored delayed release is achieved with a combination of an insoluble but semipermeable polymer and an enteric polymer, such as cellulose acetate and hydroxypropyl cellulose phthalate, respectively, as coatings. The extent of the time lag prior to complete release depends on the film-coating composition and thickness. Complete release is achieved by the addition of a cyclodextrin, namely SBE7M-β-CD with or without a pH modifier added to the tablet core to ensure complete solubilization and release of the drug substance. The film-coating properties allow the complex formation/solubilization to occur in situ. Additionally, the drug release rate can be modulated on the basis of the cyclodextrin to drug molar ratio. This approach offers a platform technology for delayed release of potent but poorly soluble drugs and the release can be modulated by adjusting the film-coating composition and thickness and/or the cyclodextrin and pH modifier, if necessary. Copyright © 2010 Wiley-Liss, Inc.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-10-15

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

  19. Identification of Weak Acids and Bases by Titration with Primary Standards. A Modern Version of an Old Analytical Chemistry Experiment.

    Science.gov (United States)

    Thompson, Robert Q.

    1988-01-01

    Describes a laboratory exercise in which acid dissociation constants and molecular weights are extracted from sample data and the sample is identified. Emphasizes accurate volumetric work while bringing to practice the concepts of acid-base equilibria, activity coefficients, and thermodynamic constants. (CW)

  20. Pentaarylfullerenes as noncoordinating cyclopentadienyl anions

    NARCIS (Netherlands)

    Bouwkamp, Marco W.; Meetsma, Auke

    2009-01-01

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

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

    Science.gov (United States)

    Funes, Silvia; de Morais, Helio Autran

    2017-03-01

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

  2. Anion-macrodipole interactions: self-assembling oligourea/amide macrocycles as anion transporters that respond to membrane polarization.

    Science.gov (United States)

    Hennig, Andreas; Fischer, Lucile; Guichard, Gilles; Matile, Stefan

    2009-11-25

    Macrocyclic urea/amide hybrids are introduced as functional, anion-selective membrane transporters in lipid bilayer membranes. Six derivatives with varying side chains (aliphatic and aromatic) and conformations (parallel and antiparallel carbonyl dipoles) are investigated by fluorescence methods, among which the more active aromatic derivatives were selected for an in-depth study. Strong response of transport activity toward anion exchange and weak response toward cation exchange establish anion selectivity for all macrocycles. "Antiparallel" macrocycles that self-assemble into "antiparallel" nanotubes without macrodipole exhibit Hofmeister selectivity. Parallel macrocycles that self-assemble into parallel nanotubes with strong macrodipole are capable of overcoming the dehydration penalty of the Hofmeister bias. Both systems show additional chloride selectivity. The activity of antiparallel and parallel nanotubes in binary mixtures of bromide/perchlorate and chloride/thiocyanate is over- and underadditive, respectively (positive and negative AMFE). The activity of antiparallel nanotubes decreases rapidly with increasing membrane polarization, whereas parallel nanotubes are inactivated at high and activated by membrane potentials at low concentration. Hill coefficients of parallel nanotubes decrease significantly with membrane polarization, whereas those of antiparallel nanotubes increase slightly. The overall unusual characteristics of parallel nanotubes call for a new transport mechanism, where macrodipole-potential interactions account for voltage sensitivity and anion-macrodipole interactions account for anion selectivity.

  3. Demonstration of multiple logic operations in a heteroditopic pyrene-phenylimidazole-terpyridine conjugate based on optical responses by selective anions and cations: an experimental and theoretical investigation.

    Science.gov (United States)

    Karmakar, Srikanta; Maity, Dinesh; Mardanya, Sourav; Baitalik, Sujoy

    2014-10-09

    Combined experimental and density functional theory (DFT) and time-dependent density functional theory (TD-DFT) studies were carried out to investigate the structural and electronic properties of a terpyridyl-phenylimidazole system covalently linked to pyrene, 10-(4-[2,2':6',2"-terpyridine]terpyridin-4'-yl-phenyl)-9H-9,11-diazacyclopenta[e]pyrene (tpy-HImzPy). X-ray crystal structure determination shows that the compound crystallized in monoclinic form with the space group P21/c. The anion and cation sensing properties of tpy-HImzPy were thoroughly studied in dimethyl sulfoxide and in mixed dimethyl sulfoxide-water medium through different channels such as absorption, steady-state and time-resolved emission, and (1)H NMR spectroscopic methods. In this work, by grafting the pyrene moiety into the terpyridyl chelating unit, an intraligand-charge-transfer sensitive chromophore has been developed whose absorption and emission behaviors are highly sensitive to selective anions and cations, and the response profiles in terms of absorption or emission intensity and wavelength toward the tested ions varied quite a lot. On the basis of these observations, we developed a unique molecular system capable of performing multiple logic functions such as INHIBIT, OR, XOR, NOR, and XNOR by simply varying the combination and level of various ionic inputs in a systematic manner. In this work, we will also be particularly interested to see the effect of selective anion and cation on the optical properties of receptor by means of computational studies and correlate them with the experimentally observed data.

  4. Study of the formation and solution properties of worm-like micelles formed using both N-hexadecyl-N-methylpiperidinium bromide-based cationic surfactant and anionic surfactant.

    Directory of Open Access Journals (Sweden)

    Zhihu Yan

    Full Text Available The viscoelastic properties of worm-like micelles formed by mixing the cationic surfactant N-hexadecyl-N-methylpiperidinium bromide (C16MDB with the anionic surfactant sodium laurate (SL in aqueous solutions were investigated using rheological measurements. The effects of sodium laurate and temperature on the worm-like micelles and the mechanism of the observed shear thinning phenomenon and pseudoplastic behavior were systematically investigated. Additionally, cryogenic transmission electron microscopy images further ascertained existence of entangled worm-like micelles.

  5. DFT-Based Explanation of the Effect of Simple Anionic Ligands on the Regioselectivity of the Heck Arylation of Acrolein Acetals

    DEFF Research Database (Denmark)

    Henriksen, Signe Teuber; Tanner, David Ackland; Cacchi, Sandro

    2009-01-01

    The Heck arylation of acrolein acetal has been studied computationally and compared to the corresponding reaction with allyl ethers. The reaction can be controlled to give either cinnamaldehydes or arylpropanoic esters by addition of different coordinating anions, acetate, or chloride....... The computational study reveals that coordinating acetate raises the energy of an intermediate sufficiently to block the access to an otherwise favorable beta-hydride elimination. The reaction path is also compared to that of allyl ethers, which always give significant amounts of cinnamyl ether products under all...... reaction conditions. The difference between the two substrate classes could be rationalized in terms of relative hydride donating power of the two substrates....

  6. Wireless charing pillow for a fully implantable hearing aid: Design of a circular array coil based on finite element analysis for reducing magnetic weak zones.

    Science.gov (United States)

    Lim, Hyung-Gyu; Kim, Jong Hoon; Shin, Dong Ho; Woo, Seong Tak; Seong, Ki Woong; Lee, Jyung Hyun; Kim, Myoung Nam; Wei, Qun; Cho, Jin-Ho

    2015-01-01

    Many types of fully implantable hearing aids have been developed. Most of these devices are implanted behind the ear. To maintain the implanted device for a long period of time, a rechargeable battery and wireless power transmission are used. Because inductive coupling is the most renowned method for wireless power transmission, many types of fully implantable hearing aids are transcutaneously powered using inductively coupled coils. Some patients with an implantable hearing aid require a method for conveniently charging their hearing aid while they are resting or sleeping. To address this need, a wireless charging pillow has been developed that employs a circular array coil as one of its primary parts. In this device, all primary coils are simultaneously driven to maintain an effective charging area regardless of head motion. In this case, however, there may be a magnetic weak zone that cannot be charged at the specific secondary coil's location on the array coil. In this study, assuming that a maximum charging distance is 4 cm, a circular array coil-serving as a primary part of the charging pillow-was designed using finite element analysis. Based on experimental results, the proposed device can charge an implantable hearing aid without a magnetic weak zone within 4 cm of the perpendicular distance between the primary and secondary coils.

  7. 4-(Dimethyl?amino)pyridinium tribromide: whole mol?ecule disorder of cation and anion

    OpenAIRE

    Ng, Seik Weng

    2009-01-01

    In the title salt, C7H11N2 +?Br3 ?, the cation and the near-linear anion [Br?Br?Br = 179.41?(8)?] both show whole-mol?ecule disorder about crystallographic twofold rotation axes. The cation is weakly hydrogen-bonded to the anion by an N?H?Br inter?action. The crystal studied was found to be a racemic twin, with a twin component of nearly 50%.

  8. "Naked" Lithium Cation: Strongly Activated Metal Cations Facilitated by Carborane Anions.

    Science.gov (United States)

    Kitazawa, Yu; Takita, Ryo; Yoshida, Kengo; Muranaka, Atsuya; Matsubara, Seijiro; Uchiyama, Masanobu

    2017-02-17

    Experimental and spectroscopic studies revealed unprecedented reactivity of a "naked" lithium cation with very weakly coordinating anions, including carborane anions. The superactivated lithium cation has greatly enhanced Lewis acidic character and mediates various organic reactions such as carbonyl-ene reaction, NBS-bromination of unactivated aromatics, and Friedel-Crafts alkylation, which are not promoted by conventional lithium salts. Chemical robustness of the counteranion also plays an important role in the chemistry of the strongly activated lithium cation.

  9. WEAK GORENSTEIN GLOBAL DIMENSION

    OpenAIRE

    Bennis, Driss

    2010-01-01

    In this paper, we investigate the weak Gorenstein global dimensions. We are mainly interested in studying the problem when the left and right weak Gorenstein global dimensions coincide. We first show, for GF-closed rings, that the left and right weak Gorenstein global dimensions are equal when they are finite. Then, we prove that the same equality holds for any two-sided coherent ring. We conclude the paper with some examples and a brief discussion of the scope and limits of our results.

  10. Performance analysis of automated evaluation of Crithidia luciliae-based indirect immunofluorescence tests in a routine setting - strengths and weaknesses.

    Science.gov (United States)

    Hormann, Wymke; Hahn, Melanie; Gerlach, Stefan; Hochstrate, Nicola; Affeldt, Kai; Giesen, Joyce; Fechner, Kai; Damoiseaux, Jan G M C

    2017-11-27

    Antibodies directed against dsDNA are a highly specific diagnostic marker for the presence of systemic lupus erythematosus and of particular importance in its diagnosis. To assess anti-dsDNA antibodies, the Crithidia luciliae-based indirect immunofluorescence test (CLIFT) is one of the assays considered to be the best choice. To overcome the drawback of subjective result interpretation that inheres indirect immunofluorescence assays in general, automated systems have been introduced into the market during the last years. Among these systems is the EUROPattern Suite, an advanced automated fluorescence microscope equipped with different software packages, capable of automated pattern interpretation and result suggestion for ANA, ANCA and CLIFT analysis. We analyzed the performance of the EUROPattern Suite with its automated fluorescence interpretation for CLIFT in a routine setting, reflecting the everyday life of a diagnostic laboratory. Three hundred and twelve consecutive samples were collected, sent to the Central Diagnostic Laboratory of the Maastricht University Medical Centre with a request for anti-dsDNA analysis over a period of 7 months. Agreement between EUROPattern assay analysis and the visual read was 93.3%. Sensitivity and specificity were 94.1% and 93.2%, respectively. The EUROPattern Suite performed reliably and greatly supported result interpretation. Automated image acquisition is readily performed and automated image classification gives a reliable recommendation for assay evaluation to the operator. The EUROPattern Suite optimizes workflow and contributes to standardization between different operators or laboratories.

  11. Colorimetric determination of glucosamine and glucose based on the formation of blue molybdosilicate anion and its application to the assay of saccharifying enzyme.

    Science.gov (United States)

    Katano, Hajime; Taira, Shu; Uematsu, Kohei; Kimoto, Hisashi

    2013-01-01

    A simple and convenient method of reducing monosaccharide assay is proposed. A Si(IV)-Mo(VI) solution (pH 4.9) was yellow due to the formation of the 11- and/or 12-molybdosilicate(VI) anions. By the addition of a reducing saccharide, glucosamine, the mixture turned to blue gradually, indicating that the Mo(VI) species was reduced by the saccharide to form a blue molybdosilicate anion. The molybdenum blue formation occurred more quickly when a water-miscible organic solvent, dimethyl sulfoxide, was added to the Si(IV)-Mo(VI) solution. Thus, 0.01% level glucosamine can be determined colorimetrically with microtiter plate. Oligochitosan would not interfere with the determination of the glucosamine at the same concentration. Also, a remarkable blue color development of the Si(VI)-Mo(VI) solution was observed by the addition of glucose. On the other hand, maltose, cellobiose, and water-soluble starch at the same concentration level gave no significant coloration of the reaction mixture. Thus, the present monosaccharide assay can be applied advantageously to evaluate the saccharification to produce glucosamine and glucose.

  12. History of Weak Interactions

    Science.gov (United States)

    Lee, T. D.

    1970-07-01

    While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.

  13. Reduced growth of soybean seedlings after exposure to weak microwave radiation from GSM 900 mobile phone and base station.

    Science.gov (United States)

    Halgamuge, Malka N; Yak, See Kye; Eberhardt, Jacob L

    2015-02-01

    The aim of this work was to study possible effects of environmental radiation pollution on plants. The association between cellular telephone (short duration, higher amplitude) and base station (long duration, very low amplitude) radiation exposure and the growth rate of soybean (Glycine max) seedlings was investigated. Soybean seedlings, pre-grown for 4 days, were exposed in a gigahertz transverse electromagnetic cell for 2 h to global system for mobile communication (GSM) mobile phone pulsed radiation or continuous wave (CW) radiation at 900 MHz with amplitudes of 5.7 and 41 V m(-1) , and outgrowth was studied one week after exposure. The exposure to higher amplitude (41 V m(-1)) GSM radiation resulted in diminished outgrowth of the epicotyl. The exposure to lower amplitude (5.7 V m(-1)) GSM radiation did not influence outgrowth of epicotyl, hypocotyls, or roots. The exposure to higher amplitude CW radiation resulted in reduced outgrowth of the roots whereas lower CW exposure resulted in a reduced outgrowth of the hypocotyl. Soybean seedlings were also exposed for 5 days to an extremely low level of radiation (GSM 900 MHz, 0.56 V m(-1)) and outgrowth was studied 2 days later. Growth of epicotyl and hypocotyl was found to be reduced, whereas the outgrowth of roots was stimulated. Our findings indicate that the observed effects were significantly dependent on field strength as well as amplitude modulation of the applied field. © 2015 Wiley Periodicals, Inc.

  14. The impact of reduced gastric acid secretion on dissolution of salts of weak bases in the fasted upper gastrointestinal lumen: Data in biorelevant media and in human aspirates.

    Science.gov (United States)

    Litou, Chara; Vertzoni, Maria; Xu, Wei; Kesisoglou, Filippos; Reppas, Christos

    2017-06-01

    To propose media for simulating the intragastric environment under reduced gastric acid secretion in the fasted state at three levels of simulation of the gastric environment and evaluate their usefulness in evaluating the intragastric dissolution of salts of weak bases. To evaluate the importance of bicarbonate buffer in biorelevant in vitro dissolution testing when using Level II biorelevant media simulating the environment in the fasted upper small intestine, regardless of gastric acid secretions. Media for simulating the hypochlorhydric and achlorhydric conditions in stomach were proposed using phosphates, maleates and bicarbonates buffers. The impact of bicarbonates in Level II biorelevant media simulating the environment in upper small intestine was evaluated so that pH and bulk buffer capacity were maintained. Dissolution data were collected using two model compounds, pioglitazone hydrochloride and semifumarate cocrystal of Compound B, and the mini-paddle dissolution apparatus in biorelevant media and in human aspirates. Simulated gastric fluids proposed in this study were in line with pH, buffer capacity, pepsin content, total bile salt/lecithin content and osmolality of the fasted stomach under partial and under complete inhibition of gastric acid secretion. Fluids simulating the conditions under partial inhibition of acid secretion were useful in simulating concentrations of both model compounds in gastric aspirates. Bicarbonates in Level III biorelevant gastric media and in Level II biorelevant media simulating the composition in the upper intestinal lumen did not improve simulation of concentrations in human aspirates. Level III biorelevant media for simulating the intragastric environment under hypochlorhydric conditions were proposed and their usefulness in the evaluation of concentrations of two model salts of weak bases in gastric aspirates was shown. Level II biorelevant media for simulating the environment in upper intestinal lumen led to

  15. Anion selective membrane. [ion exchange resins and ion exchange membrane electrolytes for electrolytic cells

    Science.gov (United States)

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

    1975-01-01

    Experimental anion permselective membranes were prepared and tested for their suitability as cell separators in a chemical redox power storage system being developed at NASA-Lewis Research Center. The goals of long-term (1000 hr) oxidative and thermal stability at 80 C in FeCl3 and CrCl3 electrolytes were met by most of the weak base and strong base amino exchange groups considered in the program. Good stability is exhibited by several of the membrane substrate resins. These are 'styrene' divinylbenzene copolymer and PVC film. At least four membrane systems produce strong flexible films with electrochemical properties (resistivity, cation transfer) superior to those of the 103QZL, the most promising commercial membrane. The physical and chemical properties of the resins are listed.

  16. Anion induced conformational preference of CαNN motif residues in functional proteins.

    Science.gov (United States)

    Patra, Piya; Ghosh, Mahua; Banerjee, Raja; Chakrabarti, Jaydeb

    2017-12-01

    Among different ligand binding motifs, anion binding C α NN motif consisting of peptide backbone atoms of three consecutive residues are observed to be important for recognition of free anions, like sulphate or biphosphate and participate in different key functions. Here we study the interaction of sulphate and biphosphate with C α NN motif present in different proteins. Instead of total protein, a peptide fragment has been studied keeping C α NN motif flanked in between other residues. We use classical force field based molecular dynamics simulations to understand the stability of this motif. Our data indicate fluctuations in conformational preferences of the motif residues in absence of the anion. The anion gives stability to one of these conformations. However, the anion induced conformational preferences are highly sequence dependent and specific to the type of anion. In particular, the polar residues are more favourable compared to the other residues for recognising the anion. © 2017 Wiley Periodicals, Inc.

  17. Revisiting the Anionic Polymerization of Methyl Ethacrylate

    Energy Technology Data Exchange (ETDEWEB)

    Kennemur, Justin G. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee FL 32306-4390 USA; Bates, Frank S. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis MN 55455-0431 USA; Hillmyer, Marc A. [Department of Chemistry, University of Minnesota, Minneapolis MN 55455-0431 USA

    2017-09-26

    Synthesis of poly(methyl ethacrylate), (PMEA), in tetrahydrofuran at -78 °C using anionic polymerization techniques results in high molar mass (>30 kg mol-1), low dispersity (1.3), and high conversion (>81%). The molar masses of a series of samples are consistent with values anticipated by the monomer-to-initiator ratio and conversion. These results represent a significant improvement to earlier reported attempts to prepare PMEA using anionic methods. Successful diblock polymerization of polystyrene-block-PMEA, (PS-PMEA), and poly(4-tert-butylstyrene)-block-PMEA, (PtBS-PMEA), is achieved through sequential anionic polymerization techniques with dispersities as low as 1.06 and segment molar fractions close to those targeted. Broad principal scattering peaks observed by small-angle X-ray scattering (SAXS) for symmetric PS-PMEA at relatively high molar mass (39 kg mol-1) suggests an effective interaction parameter (χeff) that is smaller than for PS-block-poly(methyl methacrylate). On the other hand, PtBS-PMEA block polymers form a well-ordered morphology based on SAXS measurements and is attributable to the more hydrophobic PtBS segment. These results confirm the viability of PMEA as a new constituent in the expanding suite of polymers suitable for preparing nanostructured block polymers.

  18. Empirical correlation methods for temporary anions.

    Science.gov (United States)

    Sommerfeld, Thomas; Weber, Rebecca J

    2011-06-23

    A temporary anion is a short-lived radical anion that decays through electron autodetachment into a neutral molecule and a free electron. The energies of these metastable species are often predicted using empirical correlation methods because ab initio predictions are computationally very expensive. Empirical correlation methods can be justified in the framework of Weisskopf-Fano-Feshbach theory but tend to work well only within closely related families of molecules or within a restricted energy range. The reason for this behavior can be understood using an alternative theoretical justification in the framework of the Hazi-Taylor stabilization method, which suggests that the empirical parameters do not so much correct for the coupling of the computed state to the continuum but for electron correlation effects and that therefore empirical correlation methods can be improved by using more accurate electronic structure methods to compute the energy of the confined electron. This idea is tested by choosing a heterogeneous reference set of temporary states and comparing empirical correlation schemes based on Hartree-Fock orbital energies, Kohn-Sham orbital energies, and attachment energies computed with the equation-of-motion coupled-cluster method. The results show that using more reliable energies for the confined electron indeed enhances the predictive power of empirical correlation schemes and that useful correlations can be established beyond closely related families of molecules. Certain types of σ* states are still problematic, and the reasons for this behavior are analyzed. On the other hand, preliminary results suggest that the new scheme can even be useful for predicting energies of bound anions at a fraction of the computational cost of reliable ab initio calculations. It is then used to make predictions for bound and temporary states of the furantrione and croconic acid radical anions.

  19. Synthesis and Crystal Structure of a Zn(II-Based MOF Bearing Neutral N-Donor Linker and SiF62− Anion

    Directory of Open Access Journals (Sweden)

    Biplab Manna

    2018-01-01

    Full Text Available A novel three-dimensional two-fold interpenetrated bi-porous metal-organic framework IPM-325 (IPM: IISER Pune Materials having pcu topology was synthesized at room temperature. Single crystal X-ray diffraction (SC-XRD study revealed that the compound crystallizes in monoclinic lattice with molecular formula {[Zn(L2 (SiF6] (CH2Cl2 xG}n where G = Guests. All metal centers were found to have octahedral geometry. From single crystal analysis it can be inferred that SiF62− anion play a vital role in extending the dimensionality of the framework by bridging between two metal centers. Interestingly, IPM-325 exhibited two-step structural transformation maintaining the crystallinity of the framework as characterized by powder X-ray diffraction (PXRD.

  20. The Roles of Acids and Bases in Enzyme Catalysis

    Science.gov (United States)

    Weiss, Hilton M.

    2007-01-01

    Many organic reactions are catalyzed by strong acids or bases that protonate or deprotonate neutral reactants leading to reactive cations or anions that proceed to products. In enzyme reactions, only weak acids and bases are available to hydrogen bond to reactants and to transfer protons in response to developing charges. Understanding this…

  1. Formation and stabilization of antimicrobial delivery systems based on electrostatic complexes of cationic-non-ionic mixed micelles and anionic polysaccharides.

    Science.gov (United States)

    Asker, D; Weiss, J; McClements, D J

    2011-02-09

    Lauric arginate (LAE) is a cationic surfactant that is of great interest to the food industry because of its strong antimicrobial activity. However, its application within foods and beverages is currently restricted because of its limited solubility in aqueous solutions and its bitter taste, which have been associated with its cationic nature. This study examines whether electrostatic complexes between cationic LAE mixed micelles and anionic polysaccharides could be used to improve LAE functionality. Two types of pectin (high and low methoxyl) were titrated into buffer solutions containing either LAE micelles or LAE/Tween 20 mixed micelles (pH 3.5, 50 mM citrate buffer). The electrical characteristics of the micelles or micelle/pectin complexes were assessed by microelectrophoresis measurements, while their stability to aggregation was evaluated by light scattering measurements. LAE micelle/pectin complexes formed large aggregates that rapidly sedimented. On the other hand, mixed micelle/pectin complexes (1:1 LAE/Tween 20, w/w) were stable to aggregation and formed clear solutions. The electrical charge of mixed micelles changed from +8 to -15 mV when the pectin concentration was increased (0.00-0.05 wt %), indicating an electrostatic interaction between anionic pectin molecules and cationic micelles. Lower concentrations of low methoxyl pectin were required (0.01 wt %) to change the net charge of mixed micelles from positive to negative than high methoxyl pectin (0.025 wt %). Our results suggest that the addition of pectin to mixed LAE/Tween 20 micelles leads to the formation of electrostatic complexes that may be useful as functional ingredients in food and other products.

  2. A hybrid DFT based investigation of the photocatalytic activity of cation-anion codoped SrTiO3 for water splitting under visible light.

    Science.gov (United States)

    Modak, Brindaban; Srinivasu, K; Ghosh, Swapan K

    2014-11-28

    In this study, the effect of cation (Mo or W) and anion (N) codoping on the band structure of SrTiO3 is investigated to improve its photocatalytic activity for water splitting under sunlight. We consider both the non-compensated and compensated codoping strategies using different ratios of the cationic and anionic dopants. The present study employs hybrid density functional theory to describe the electronic structure of all the systems accurately. Although non-compensated (1 : 1) codoping reduces the band gap significantly, the presence of localized impurity states may hinder charge carrier mobility. This also changes the positions of the band edges to such an extent that the (Mo/W, N)-codoped SrTiO3 system becomes ineffective for overall water splitting. Besides, the formation of charge compensating defects may contribute to the carrier loss. On the other hand, compensated (1 : 2) codoping not only reduces the band gap to shift the absorption curve towards the visible region, but also passivates the impurity states completely, ensuring improved photoconversion efficiency. The reduction of the band gap is found to be more prominent in the case of (W, 2N)-codoped SrTiO3 than (Mo, 2N)-codoped SrTiO3. In both the cases, the band edge positions are found to satisfy the thermodynamic criteria for overall water splitting. Our calculation predicts that the codoping of (Mo/W) and N in the 1 : 2 ratio also enhances the reducing properties at the conduction band in comparison to that in the undoped SrTiO3, which is beneficial for hydrogen release in water splitting. The present study thus demonstrates the effect of the nature of the dopant elements as well as their proportion to achieve the best outcome of the designed material for practical applications.

  3. Structure and magnetism in Fe-Gd based dinuclear and chain systems. The interplay of weak exchange coupling and zero field splitting effects.

    Science.gov (United States)

    Ferbinteanu, Marilena; Cimpoesu, Fanica; Gîrţu, Mihai A; Enachescu, Cristian; Tanase, Stefania

    2012-01-02

    The synthesis and characterization of two Fe-Gd systems based on bpca(-) (Hbpca = bis(2-pyridilcarbonyl)amine) as bridging ligand is presented, taking the systems as a case study for structure-property correlations. Compound 1, [Fe(LS)(II)(μ-bpca)(2)Gd(NO(3))(2)(H(2)O)]NO(3)·2CH(3)NO(2), is a zigzag polymer, incorporating the diamagnetic low spin Fe(LS)(II) ion. The magnetism of 1 is entirely determined by the weak zero field splitting (ZFS) effect on the Gd(III) ion. Compound 2 is a Fe(III)-Gd(III) dinuclear compound, [Fe(LS)(III)(bpca)(μ-bpca)Gd(NO(3))(4)]·4CH(3)NO(2)·CH(3)OH, its magnetism being interpreted as due to the antiferromagnetic coupling between the S(Fe) = ½ and S(Gd) = 7/2 spins, interplayed with the local ZFS on the lanthanide center. In both systems, the d-f assembly is determined by the bridging capabilities of the ambidentate bpca(-) ligand, which binds the d ion by a tridentate moiety with nitrogen donors and the f center by the diketonate side. We propose a spin delocalization and polarization mechanism that rationalizes the factors leading to the antiferromagnetic d-f coupling. Although conceived for compound 2, the scheme can be proposed as a general mechanism. The rationalization of the weak ZFS effects on Gd(III) by multiconfiguration and spin-orbit ab initio calculations allowed us to determine the details of the small but still significant anisotropy of Gd(III) ion in the coordination sites of compounds 1 and 2. The outlined methodologies and generalized conclusions shed new light on the field of gadolinium coordination magnetochemistry.

  4. Weak acid-concentration Atot and dissociation constant Ka of plasma proteins in racehorses.

    Science.gov (United States)

    Stampfli, H R; Misiaszek, S; Lumsden, J H; Carlson, G P; Heigenhauser, G J

    1999-07-01

    The plasma proteins are a significant contributor to the total weak acid concentration as a net anionic charge. Due to potential species difference, species-specific values must be confirmed for the weak acid anionic concentrations of proteins (Atot) and the effective dissociation constant for plasma weak acids (Ka). We studied the net anion load Atot of equine plasma protein in 10 clinically healthy mature Standardbred horses. A multi-step titration procedure, using a tonometer covering a titration range of PCO2 from 25 to 145 mmHg at 37 degrees C, was applied on the plasma of these 10 horses. Blood gases (pH, PCO2) and electrolytes required to calculate the strong ion difference ([SID] = [(Na(+) + K(+) + Ca(2+) + Mg(2+))-(Cl(-) + Lac(-) + PO4(2-))]) were simultaneously measured over a physiological pH range from 6.90-7.55. A nonlinear regression iteration to determine Atot and Ka was performed using polygonal regression curve fitting applied to the electrical neutrality equation of the physico-chemical system. The average anion-load Atot for plasma protein of 10 Standardbred horses was 14.89 +/- 0.8 mEq/l plasma and Ka was 2.11 +/- 0.50 x 10(-7) Eq/l (pKa = 6.67). The derived conversion factor (iterated Atot concentration/average plasma protein concentration) for calculation of Atot in plasma is 0.21 mEq/g protein (protein-unit: g/l). This value compares closely with the 0.24 mEq/g protein determined by titration of Van Slyke et al. (1928) and 0.22 mEq/g protein recently published by Constable (1997) for horse plasma. The Ka value compares closely with the value experimentally determined by Constable in 1997 (2.22 x 10(7) Eq/l). Linear regression of a set of experimental data from 5 Thoroughbred horses on a treadmill exercise test, showed excellent correlation with the regression lines not different from identity for the calculated and measured variables pH, HCO3 and SID. Knowledge of Atot and Ka for the horse is useful especially in exercise studies and in

  5. Exercise-based rehabilitation after hospital discharge for survivors of critical illness with intensive care unit-acquired weakness: A pilot feasibility trial.

    Science.gov (United States)

    Connolly, Bronwen; Thompson, April; Douiri, Abdel; Moxham, John; Hart, Nicholas

    2015-06-01

    The aim of this study was to investigate feasibility of exercise-based rehabilitation delivered after hospital discharge in patients with intensive care unit-acquired weakness (ICU-AW). Twenty adult patients, mechanically ventilated for more than 48 hours, with ICU-AW diagnosis at ICU discharge were included in a pilot feasibility randomized controlled trial receiving a 16-session exercise-based rehabilitation program. Twenty-one patients without ICU-AW participated in a nested observational cohort study. Feasibility, clinical, and patient-centered outcomes were measured at hospital discharge and at 3 months. Intervention feasibility was demonstrated by high adherence and patient acceptability, and absence of adverse events, but this must be offset by the low proportion of enrolment for those screened. The study was underpowered to detect effectiveness of the intervention. The use of manual muscle testing for the diagnosis of ICU-AW lacked robustness as an eligibility criterion and lacked discrimination for identifying rehabilitation requirements. Process evaluation of the trial identified methodological factors, categorized by "population," "intervention," "control group," and "outcome." Important data detailing the design, conduct, and implementation of a multicenter randomized controlled trial of exercise-based rehabilitation for survivors of critical illness after hospital discharge have been reported. Clinical Trials Identifier NCT00976807. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  6. Impact of Acid-Reducing Agents on the Pharmacokinetics of Palbociclib, a Weak Base With pH-Dependent Solubility, With Different Food Intake Conditions.

    Science.gov (United States)

    Sun, Wan; Klamerus, Karen J; Yuhas, Lisa M; Pawlak, Sylvester; Plotka, Anna; O'Gorman, Melissa; Kirkovsky, Leonid; Kosa, Maha; Wang, Diane

    2017-11-01

    Palbociclib free base capsule is a weak base drug with highly pH-dependent solubility. In vitro and in vivo studies evaluated the impact of acid-reducing agents on exposure of palbociclib and determined whether the impact, if any, can be mitigated by food. A drug-drug interaction study (study 1) was conducted first under fasted conditions and showed that coadministration of multiple doses of the proton-pump inhibitor rabeprazole substantially reduced palbociclib mean area under the concentration-time curve from time 0 to infinity and maximum observed plasma concentration by 62% and 80%, respectively. In vitro assessment suggested that the presence of bile salt mixed micelles to mimic the fed state can significantly enhance the solubility of palbociclib. Subsequently, study 2 was conducted under fed conditions and demonstrated that coadministration of rabeprazole decreased palbociclib maximum observed plasma concentration by 41% but had limited impact on area under the concentration-time curve from 0 to infinity (13% decrease). This study also showed that the histamine-2 receptor antagonist famotidine and local antacid with staggered dosing had no impact on palbociclib exposure under fed conditions. Food intake effectively mitigated the impact of acid-reducing agents on palbociclib exposure. Palbociclib free base capsule should be taken with food, and acid-reducing agent use does not need to be avoided. © 2017, The American College of Clinical Pharmacology.

  7. Treatment of acute non-anion gap metabolic acidosis

    Science.gov (United States)

    Kraut, Jeffrey A.; Kurtz, Ira

    2015-01-01

    Acute non-anion gap metabolic acidosis, also termed hyperchloremic acidosis, is frequently detected in seriously ill patients. The most common mechanisms leading to this acid–base disorder include loss of large quantities of base secondary to diarrhea and administration of large quantities of chloride-containing solutions in the treatment of hypovolemia and various shock states. The resultant acidic milieu can cause cellular dysfunction and contribute to poor clinical outcomes. The associated change in the chloride concentration in the distal tubule lumen might also play a role in reducing the glomerular filtration rate. Administration of base is often recommended for the treatment of acute non-anion gap acidosis. Importantly, the blood pH and/or serum bicarbonate concentration to guide the initiation of treatment has not been established for this type of metabolic acidosis; and most clinicians use guidelines derived from studies of high anion gap metabolic acidosis. Therapeutic complications resulting from base administration such as volume overload, exacerbation of hypertension and reduction in ionized calcium are likely to be as common as with high anion gap metabolic acidosis. On the other hand, exacerbation of intracellular acidosis due to the excessive generation of carbon dioxide might be less frequent than in high anion gap metabolic acidosis because of better tissue perfusion and the ability to eliminate carbon dioxide. Further basic and clinical research is needed to facilitate development of evidence-based guidelines for therapy of this important and increasingly common acid–base disorder. PMID:25852932

  8. Electroactive ionic liquids based on 2,5-ditert-butyl-1,4-dimethoxybenzene and triflimide anion as redox shuttle for Li4Ti5O12/LiFePO4 lithium-ion batteries

    Science.gov (United States)

    Gélinas, Bruno; Bibienne, Thomas; Dollé, Mickael; Rochefort, Dominic

    2017-12-01

    In order to increase the solubility and oxidation potential of redox shuttles, electroactive ionic liquids (RILs) based on the modification of 1,4-dimethoxybenzene with triflimide anions were synthesized. We developed two synthetic routes to obtain these RILs in which the triflimide was either linked on the benzene ring or as a ether on 2,5-ditert-butyl-1,4-dimethoxybenzene (DDB). These RILs all have melting points below 100 °C, but above room temperature. The structural impact of electroactive anion was evaluated in this study by determining the redox potential and electrochemical stability. The electrochemical properties of these RILs were investigated by cyclic voltammetry and the diffusion coefficients were measured by double potential step chronoamperometry. The viscosity and ionic conductivity measurements of redox-active electrolyte were obtained at different temperatures and the RIL additives are shown to have a low impact on these electrolyte properties at concentrations up to 0.3 M. The charge-overcharge-discharge cycles of Li/LiFePO4 half-cells and Li4Ti5O12/LiFePO4 full cells with a 100% overcharge are presented using redox-active electrolyte (0.3 M concentration level) at 0.1 C rate. This study highlights the potential of electroactive ionic liquids as highly soluble and stable functional additives in Li-ion battery electrolytes.

  9. High conductive, long-term durable, anhydrous proton conductive solid-state electrolyte based on a metal-organic framework impregnated with binary ionic liquids: Synthesis, characteristic and effect of anion

    Science.gov (United States)

    Chen, Hui; Han, Shu-Yan; Liu, Rui-Heng; Chen, Teng-Fei; Bi, Kai-Lun; Liang, Jian-Bo; Deng, Yu-Heng; Wan, Chong-Qing

    2018-02-01

    Incorporating ionic liquids (abbreviated as ILs) into porous metal-organic framework (MOF) to obtain ILs@MOF nanocomposites is documented as a feasible method to achieve new type of anhydrous proton conductor with high performance. We newly synthesized a series of ILs with different acid counter anions (R-SO3-) and their ILs@MOF hybrid materials, i.e. SA-EIMS@MIL-101, MSA-EIMS@MIL-101 and PTSA-EIMS@MIL-101 (SA = sulfate acid, MSA = methanesulfonate acid, PTSA = p-toluenesulfonate acid, EIMS = 1-(1-ethyl-3-imidazolium)propane-3-sulfonate). Such hybrid materials displayed as anhydrous proton conduction with long-term durability even heated at 150 °C open to air. σ value of SA-EIMS@MIL-101 is up to 1.89 × 10-3 S cm-1, being in the range of the most conductive MOF-based materials. MOF support exhibited favorable proton transport and long-term retention for ILs. Anion volumes of R-SO3- displayed significant effects on the proton conductivity of such hybrid ILs@MOF materials. The smaller the van der Waals volume of R-SO3- is, the higher the conductivity of ILs@MOF is. This work suggests that the combination of a variety of the incorporated ILs and a MOF framework would afford high proton transport and gives an idea to explore the safe, anhydrous, solid-state electrolyte for high temperature proton exchange membrane fuel cell.

  10. Four Novel Zn (II Coordination Polymers Based on 4′-Ferrocenyl-3,2′:6′,3′′-Terpyridine: Engineering a Switch from 1D Helical Polymer Chain to 2D Network by Coordination Anion Modulation

    Directory of Open Access Journals (Sweden)

    Lufei Xiao

    2017-11-01

    Full Text Available Four novel ZnII coordination polymers, [(ZnCl22(L2]n (1, [(ZnBr22(L2]n (2, and [(ZnI22(L2]n (3 and {[Zn(SCN2]1.5(L3}n (4, have been synthesized based on 4′-ferrocenyl-3,2′:6′,3′′-terpyridine with ZnII ions and different coordination anions under similar ambient conditions. Their structures have been confirmed using single crystal X-ray diffraction analysis, showing that complexes 1–3 are one-dimensional (1D double-stranded metal ion helical polymer chains and complex 4 is of a two-dimensional (2D network. The structural transformations of them from a 1D polymer chain to a 2D network under the influence of the coordination anions has been systematic investigated. Furthermore, the optical band gaps have been measured by optical diffuse reflectance spectroscopy, revealing that the ligand and the complexes should have semiconductor properties.

  11. Weak neutral-current interactions

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, R.M.

    1978-08-01

    The roles of each type of experiment in establishing uniquely the values of the the neutral-current couplings of u and d quarks are analyzed together with their implications for gauge models of the weak and electromagnetic interactions. An analysis of the neutral-current couplings of electrons and of the data based on the assumption that only one Z/sup 0/ boson exists is given. Also a model-independent analysis of parity violation experiments is discussed. 85 references. (JFP)

  12. Competing weak localization and weak antilocalization in ultrathin topological insulators.

    Science.gov (United States)

    Lang, Murong; He, Liang; Kou, Xufeng; Upadhyaya, Pramey; Fan, Yabin; Chu, Hao; Jiang, Ying; Bardarson, Jens H; Jiang, Wanjun; Choi, Eun Sang; Wang, Yong; Yeh, Nai-Chang; Moore, Joel; Wang, Kang L

    2013-01-09

    We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films of (Bi(0.57)Sb(0.43))(2)Te(3) below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil a striking competition between weak localization and weak antilocalization at low magnetic fields in nonmagnetic ultrathin films, possibly owing to the change of the net Berry phase. Furthermore, when the Fermi level is swept into the surface gap of ultrathin samples, the overall unitary behaviors are revealed at higher magnetic fields, which are in contrast to the pure WAL signals obtained in thicker films. Our findings show an exotic phenomenon characterizing the gapped TI surface states and point to the future realization of quantum spin Hall effect and dissipationless TI-based applications.

  13. Charged weak currents

    CERN Document Server

    Turlay, René

    1979-01-01

    In this review of charged weak currents the author concentrates on inclusive high energy neutrino physics. The authors discusses the general structure of charged currents, new results on total cross- sections, the Callan-Gross relation, antiquark distributions, scaling violations and tests of QCD. A very short summary on multilepton physics is given. (44 refs).

  14. On Weak Markov's Principle

    DEFF Research Database (Denmark)

    Kohlenbach, Ulrich Wilhelm

    2002-01-01

    We show that the so-called weak Markov's principle (WMP) which states that every pseudo-positive real number is positive is underivable in E-HA + AC. Since allows one to formalize (atl eastl arge parts of) Bishop's constructive mathematics, this makes it unlikely that WMP can be proved within...

  15. Anionic Conducting Oxide Ceramics

    National Research Council Canada - National Science Library

    Dunn, Bruce

    1998-01-01

    This program has emphasized the interrelationships among synthesis, microstructure and properties for oxygen ion conducting ceramics based on copper-substituted bismuth vanadate (Bi V Cu O ), known as BICUVOX...

  16. Anion order in perovskite oxynitrides.

    Science.gov (United States)

    Yang, Minghui; Oró-Solé, Judith; Rodgers, Jennifer A; Jorge, Ana Belén; Fuertes, Amparo; Attfield, J Paul

    2011-01-01

    Transition-metal oxynitrides with perovskite-type structures are an emerging class of materials with optical, photocatalytic, dielectric and magnetoresistive properties that may be sensitive to oxide-nitride order, but the anion-ordering principles were unclear. Here we report an investigation of the representative compounds SrMO(2)N (M = Nb, Ta) using neutron and electron diffraction. This revealed a robust 1O/2(O(0.5)N(0.5)) partial anion order (up to at least 750 °C in the apparently cubic high-temperature phases) that directs the rotations of MO(4)N(2) octahedra in the room-temperature superstructure. The anion distribution is consistent with local cis-ordering of the two nitrides in each octahedron driven by covalency, which results in disordered zigzag M-N chains in planes within the perovskite lattice. Local structures for the full range of oxynitride perovskites are predicted and a future challenge is to tune properties by controlling the order and dimensionality of the anion chains and networks.

  17. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-10-06

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  18. THERMODYNAMIC ASSESSMENT OF ANIONIC LIGANDS ...

    African Journals Online (AJOL)

    DJFLEX

    2010-06-30

    Jun 30, 2010 ... ion. This brings about repulsion between the adsorbent and positively charged ion and consequently a reduction in the amount of heavy metal adsorbed at lower pH. (Lee, 1999). The effectiveness of the anionic ligands in the removal of heavy metal ions from aqueous solution seems to be low for the EDTA.

  19. Electrochemical quartz crystal microbalance analysis of the oxygen reduction reaction on Pt-based electrodes. Part 1: Effect of adsorbed anions on the oxygen reduction activities of Pt in HF, HClO4, and H2SO4 solutions.

    Science.gov (United States)

    Omura, Jun; Yano, Hiroshi; Watanabe, Masahiro; Uchida, Hiroyuki

    2011-05-17

    The effects of anion adsorption on the activities for the oxygen reduction reaction (ORR) at a Pt film electrode in electrolyte solutions (HClO(4) and HF at various concentrations) were analyzed using an electrochemical quartz crystal microbalance (EQCM) and a rotating disk electrode (RDE). With an increasing HClO(4) concentration [HClO(4)], the onset potential for the Pt oxide formation in the voltammogram shifted in the positive direction, accompanied by a compression of the hydrogen adsorption/oxidation wave to less positive potentials. This is ascribed to a specific adsorption of the ClO(4)(-) anion, because the [HClO(4)] dependence of the mass change Δm detected by EQCM in the double-layer region was found to be fitted well by a Frumkin-Temkin adsorption isotherm. The potential dependencies of Δm in both 0.1 and 0.5 M HClO(4) solutions accord well with those of the ν(Cl-O) intensities observed by in situ Fourier transform infrared (FTIR) spectroscopy in the potential range from 0.3 to 0.6 V. The kinetically controlled current densities j(k) for the ORR at the Pt-RDE were found to decrease with increasing [HClO(4)], because of the blocking of the active sites by specifically adsorbed ClO(4)(-). The values of j(k) in the non-adsorbing 0.1 M HF electrolyte solution, however, were smaller than those in 0.1 M HClO(4). It was found that the low ORR activity could be ascribed to the low H(+) activity in the weak acid solution of HF. We, for the first time, detected a reversible mass change for one or more adsorbed oxygen species on the Pt-EQCM in O(2)-saturated and He-purged HF and HClO(4) solutions. The coverages of oxygen species θ(O) on Pt were found to increase in the O(2)-saturated solution. High values of θ(O) in O(2)-saturated 7 mM HF suggest that the ORR rate was limited by the very low H(+) activity in the solution, and the adsorbed oxygen species remained on the surface because of a slow consumption rate.

  20. Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2009-03-06

    The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 microL samples of a 50 mM probe solution were injected into C(18)-bonded columns using a series of five buffered mobile phases at (SW)pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C(18)-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C(18)-bonded layer and the bulk phase.

  1. Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

    2009-01-01

    The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 {micro}L samples of a 50 mM probe solution were injected into C{sub 18}-bonded columns using a series of five buffered mobile phases at {sub W}{sup S}pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1 g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C{sub 18}-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C{sub 18}-bonded layer and the bulk

  2. Role of Electron-Driven Proton-Transfer Processes in the Ultrafast Deactivation of Photoexcited Anionic 8-oxoGuanine-Adenine and 8-oxoGuanine-Cytosine Base Pairs

    Directory of Open Access Journals (Sweden)

    Xiuxiu Wu

    2017-01-01

    Full Text Available It has been reported that 8-oxo-7,8-dihydro-guanosine (8-oxo-G, which is the main product of oxidative damage of DNA, can repair cyclobutane pyrimidine dimer (CPD lesions when incorporated into DNA or RNA strands in proximity to such lesions. It has therefore been suggested that the 8-oxo-G nucleoside may have been a primordial precursor of present-day flavins in DNA or RNA repair. Because the electron transfer leading to the splitting of a thymine-thymine pair in a CPD lesion occurs in the photoexcited state, a reasonably long excited-state lifetime of 8-oxo-G is required. The neutral (protonated form of 8-oxo-G exhibits a very short (sub-picosecond intrinsic excited-state lifetime which is unfavorable for repair. It has therefore been argued that the anionic (deprotonated form of 8-oxo-G, which exhibits a much longer excited-state lifetime, is more likely to be a suitable cofactor for DNA repair. Herein, we have investigated the exited-state quenching mechanisms in the hydrogen-bonded complexes of deprotonated 8-oxo-G− with adenine (A and cytosine (C using ab initio wave-function-based electronic-structure calculations. The calculated reaction paths and potential-energy profiles reveal the existence of barrierless electron-driven inter-base proton-transfer reactions which lead to low-lying S1/S0 conical intersections. The latter can promote ultrafast excited-state deactivation of the anionic base pairs. While the isolated deprotonated 8-oxo-G− nucleoside may have been an efficient primordial repair cofactor, the excited states of the 8-oxo-G−-A and 8-oxo-G−-C base pairs are likely too short-lived to be efficient electron-transfer repair agents.

  3. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David

    2006-01-01

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

  4. Anion-dependent formation of four coordination polymers based on N,N‧-di(3-pyridine) oxamide (DPOM): Crystal structures and luminescence

    Science.gov (United States)

    Deng, Ji-Hua; Wen, Ya-Qiong; Luo, Xu-Zhong; Zhong, Di-Chang

    2017-09-01

    Presented in this article are the anion-tuning formation, crystal structures and luminescent properties of four coordination polymers of N,N‧-di(3-pyridine) oxamide (DPOM), including two one-dimensional (1D) chain/ladder polymers, [Ni(DPOM)(H2O)4]SO4·2H2O (1) and [Cd4(DPOM)6(NO3)8] (2), as well as two 3D coordination polymers, [Zn2(DPOM)(H2O)4(SO4)2] (3) and [Cd2(DPOM)(H2O)4(SO4)2] (4). The results of single crystal X-ray diffraction analyses indicate that in these coordination polymers, DPOM ligand serves as a bridge, connecting metal ions by both terminal pyridine N atoms. 1 is a 1D chain structure formed by the bridge of DPOM. 2 is a 1D ladder-like structure featuring Cd(NO3)2 structural units bridged by DPOM ligands. Both 3 and 4 are 3D pillar-layer structures with the 2D inorganic layer ZnSO4/CdSO4 pillared by DPOM ligands. The results of photoluminescent measurements illustrate that upon excitation, 2-4 can emit fluorescence in 408, 416, and 422 nm in the solid state, respectively.

  5. Potential energy surface and binding energy in the presence of an external electric field: modulation of anion-π interactions for graphene-based receptors.

    Science.gov (United States)

    Foroutan-Nejad, Cina; Marek, Radek

    2014-02-14

    Measuring the binding energy or scanning the potential energy surface (PES) of the charged molecular systems in the presence of an external electric field (EEF) requires a careful evaluation of the origin-dependency of the energy of the system and references. Scanning the PES for charged or purely ionic systems for obtaining the intrinsic energy barriers needs careful analysis of the electric work applied on ions by the EEF. The binding energy in the presence of an EEF is different from that in the absence of an electric field as the binding energy is an anisotropic characteristic which depends on the orientation of molecules with respect to the EEF. In this contribution we discuss various aspects of the PES and the concept of binding energy in the presence of an EEF. In addition, we demonstrate that the anion-π bonding properties can be modulated by applying a uniform EEF, which has a more pronounced effect on the larger, more polarizable π-systems. An analogous behavior is presumed for cation-π systems. We predict that understanding the phenomenon introduced in the present account has enormous potential, for example, for separating charged species on the surface of polarizable two-dimensional materials such as graphene or the surface of carbon nanotubes, in desalination of water.

  6. Evaluation of a new, macroporous polyvinylpyridine resin for processing plutonium using nitrate anion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, S.F.

    1989-04-01

    Anion exchange in nitric acid is the major aqueous process used to recover and purify plutonium from impure scrap materials. Most strong-base anion exchange resins incorporate a styrene-divinylbenzene copolymer. A newly available, macroporous anion exchange resin based on a copolymer of 1-methyl-4-vinylpyridine and divinylbenzene has been evaluated. Comparative data for Pu(IV) sorption kinetics and capacity are presented for this new resin and two other commonly used anion exchange resins. The new resin offers high capacity and rapid sorption kinetics for Pu(IV) from nitric acid, as well as greatly stability to chemical and radiolytic degradation. 8 refs., 14 figs.

  7. Insights into head-column field-amplified sample stacking: Part I. Detailed study of electrokinetic injection of a weak base across a short water plug.

    Science.gov (United States)

    Šesták, Jozef; Thormann, Wolfgang

    2017-06-16

    The fundamentals of electrokinetic injection of the weak base methadone across a short water plug into a phosphate buffer at low pH were studied experimentally and with computer simulation. The current during electrokinetic injection, the formation of the analyte zone, changes occurring within and around the water plug and mass transport of all compounds in the electric field were investigated. The impact of water plug length, plug injection velocity, and composition of sample, plug and background electrolyte are discussed. Experimental data revealed that properties of sample, water plug and stacking boundary are significantly and rapidly altered during electrokinetic injection. Simulation provided insight into these changes, including the nature of the migrating boundaries and the stacking of methadone at the interface to a newly formed phosphoric acid zone. The data confirm the role of the water plug to prevent contamination of the sample by components of the background electrolyte and suggest that mixing caused by electrohydrodynamic instabilities increases the water plug conductivity. The sample conductivity must be controlled by addition of an acid to prevent generation of reversed flow which removes the water plug and to create a buffering environment. Results revealed that a large increase in background electrolyte concentration is not accompanied with a significant increase in stacking. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

    National Research Council Canada - National Science Library

    Marta Ziemnicka-Sylwester

    2013-01-01

    .... The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic "in situ" reaction of TiB2 formation and the "tailing" synthesis of boron carbide characterized by weak exothermicity...

  9. Antibacterial effect of cationic porphyrazines and anionic phthalocyanine and their interaction with plasmid DNA

    Science.gov (United States)

    Hassani, Leila; Hakimian, Fatemeh; Safaei, Elham; Fazeli, Zahra

    2013-11-01

    Resistance to antibiotics is a public health issue and identification of new antibacterial agents is one of the most important goals of pharmacological research. Among the novel developed antibacterial agents, porphyrin complexes and their derivatives are ideal candidates for use in medical applications. Phthalocyanines differ from porphyrins by having nitrogen atoms link the individual pyrrol units. The aza analogues of the phthalocyanines (azaPcs) such as tetramethylmetalloporphyrazines are heterocyclic Pc analogues. In this investigation, interaction of an anionic phthalocyanine (Cu(PcTs)) and two cationic tetrapyridinoporphyrazines including [Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+ complexes with plasmid DNA was studied using spectroscopic and gel electrophoresis methods. In addition, antibacterial effect of the complexes against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was investigated using dilution test method. The results indicated that both porphyrazines have significant antibacterial properties, but Cu(PcTs) has weak antibacterial effect. Compairing the binding of the phthalocyanine and the porphyrazines to DNA demonstrated that the interaction of cationic porphyrazines is stronger than the anionic phthalocyanine remarkably. The extent of hypochromicity and red shift of absorption spectra indicated preferential intercalation of the two porphyrazine into the base pairs of DNA helix. Gel electrophoresis result implied Cu(2,3-tmtppa) and Cu(3,4-tmtppa) are able to perform cleavage of the plasmid DNA. Consequently, DNA binding and cleavage might be one of the antibacterial mechanisms of the complexes.

  10. Recognition, Sensing and Separation of Anions

    Indian Academy of Sciences (India)

    Dr Pradyut Ghosh

    2016-11-05

    Nov 5, 2016 ... Anion Recognition. Basic Science: Coordination chemistry of anions. Potential Applications: Development of Selective. Anion Receptor towards. • Chemical Separation. • Clean Environment. • Safe Water. • Chemical Sensing. Inorg. Chem. 2011, 50, 4229. Ion Sensing. Inorg. Chem. 2010, 49, 4447. Chem.

  11. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad

    2016-08-18

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

  12. Ion-π interactions in ligand design for anions and main group cations.

    Science.gov (United States)

    Watt, Michelle M; Collins, Mary S; Johnson, Darren W

    2013-04-16

    Interactions between ions and aromatic rings are now a mainstay in the field of supramolecular chemistry. The prototypical cation-π interaction, first characterized in the gas phase, is now well-known as an important contributor to protein structure and enzyme function and as a noncovalent force found in many synthetic systems. The complementary "anion-π interaction"-defined as an electrostatic attraction between an anion positioned over the centroid of an aromatic ring-has recently emerged as another reversible ion-π interaction in supramolecular systems. This type of interaction could offer new selectivity in binding poorly basic, strongly solvated anions and may also affect structure, biological function, and anion transport. This Account describes our group's efforts in ion-π interactions in two areas. We first describe a series of self-assembled Group 15 (pnictogen)-thiolate complexes, all featuring prominent cation-π interactions between the trivalent pnictogen and an aromatic ring of the ligand. This structural feature appears to stabilize a variety of self-assembled dinuclear macrocycles, dinuclear M2L3 cryptand-analogues, and a tetranuclear As4L2 metallocyclophane. These complexes are all remarkably robust and feature intramolecular cation-π interactions, which suggest that these interactions could be an important feature in ligand design for the Group 15 elements. We also highlight our efforts to characterize the interaction between anions and electron-deficient aromatic rings in solution. Complementary crystallographic and computational studies suggest that off-center weak-σ interactions play the dominant role in stabilizing the anion-arene adducts unless an acidic CH bond is present to participate in favorable CH···anion hydrogen bonds. In solution the weak-σ complexes show downfield shifts of the proton resonances in their NMR spectra. With more polarizable anions such as bromide and iodide, we also observe anion binding by UV

  13. Composite weak bosons

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, M.

    1988-04-01

    Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.

  14. Quantum correlation cost of the weak measurement

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun; Wu, Shao-xiong; Yu, Chang-shui, E-mail: quaninformation@sina.com

    2014-12-15

    Quantum correlation cost (QCC) characterizing how much quantum correlation is used in a weak-measurement process is presented based on the trace norm. It is shown that the QCC is related to the trace-norm-based quantum discord (TQD) by only a factor that is determined by the strength of the weak measurement, so it only catches partial quantumness of a quantum system compared with the TQD. We also find that the residual quantumness can be ‘extracted’ not only by the further von Neumann measurement, but also by a sequence of infinitesimal weak measurements. As an example, we demonstrate our outcomes by the Bell-diagonal state.

  15. Capillary Electrophoresis as Analysis Technique for Battery Electrolytes: (i Monitoring Stability of Anions in Ionic Liquids and (ii Determination of Organophosphate-Based Decomposition Products in LiPF6-Based Lithium Ion Battery Electrolytes

    Directory of Open Access Journals (Sweden)

    Marcelina Pyschik

    2017-09-01

    Full Text Available In this work, a method for capillary electrophoresis (CE hyphenated to a high-resolution mass spectrometer was presented for monitoring the stability of anions in ionic liquids (ILs and in commonly used lithium ion battery (LIB electrolytes. The investigated ILs were 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonylimide (PYR13TFSI and 1-methyl-1-propylpyrrolidinium bis(fluorosulfonylimide (PYR13FSI. The method development was conducted by adjusting the following parameters: buffer compositions, buffer concentrations, and the pH value. Also the temperature and the voltage applied on the capillary were optimized. The ILs were aged at room temperature and at 60 °C for 16 months each. At both temperatures, no anionic decomposition products of the FSI− and TFSI− anions were detected. Accordingly, the FSI− and TFSI− anions were thermally stable at these conditions. This method was also applied for the investigation of LIB electrolyte samples, which were aged at 60 °C for one month. The LP30 (50/50 wt. % dimethyl carbonate/ethylene carbonate and 1 M lithium hexafluorophosphate electrolyte was mixed with the additive 1,3-propane sultone (PS and with one of the following organophosphates (OP: dimethyl phosphate (DMP, diethyl phosphate (DEP, and triethyl phosphate (TEP, to investigate the influence of these compounds on the formation of OPs.

  16. Cation-Anion Balance during Potassium and Sodium Absorption by Barley Roots

    Science.gov (United States)

    Jackson, P. C.; Adams, H. R.

    1963-01-01

    Steady-state rates of potassium ion and sodium ion absorption by excised barley roots accompanied by various anions were compared with the rates of anion absorption and the concomitant H+ and base release by the roots. The cation absorption rates were found to be independent of the identities, concentrations, and rates of absorption of the anions of the external solution, including bicarbonate. Absorption of the anion of the salt plus bicarbonate could not account for the cation absorption. H+ is released during cation absorption and base during anion absorption. The magnitude by which one or the other predominates depends on the relative rates of anion and cation absorption under various conditions of pH, cation and anion concentration, and inhibitor concentrations. The conclusion is that potassium and sodium ions are absorbed independently of the anions of the absorption solution in exchange for H+, while anions are exchanged for a base. The H+ release reflects a specificity between K+ and Na+ absorption such that it appears to be H+ exchanged in the specific rate-limiting reactions of the cation absorption. PMID:13964256

  17. The Weak Haagerup Property II

    DEFF Research Database (Denmark)

    Haagerup, Uffe; Knudby, Søren

    2015-01-01

    The weak Haagerup property for locally compact groups and the weak Haagerup constant were recently introduced by the second author [27]. The weak Haagerup property is weaker than both weak amenability introduced by Cowling and the first author [9] and the Haagerup property introduced by Connes [6......] and Choda [5]. In this paper, it is shown that a connected simple Lie group G has the weak Haagerup property if and only if the real rank of G is zero or one. Hence for connected simple Lie groups the weak Haagerup property coincides with weak amenability. Moreover, it turns out that for connected simple...... Lie groups the weak Haagerup constant coincides with the weak amenability constant, although this is not true for locally compact groups in general. It is also shown that the semidirect product R2 × SL(2,R) does not have the weak Haagerup property....

  18. Polymerization of anionic wormlike micelles.

    Science.gov (United States)

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

    2006-01-31

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

  19. Laser Cooling of Molecular Anions

    CERN Document Server

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

    2015-01-01

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

  20. Organic superconductors with an incommensurate anion structure

    Directory of Open Access Journals (Sweden)

    Tadashi Kawamoto and Kazuo Takimiya

    2009-01-01

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

  1. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

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

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...... and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  2. Gas-Phase Anionic ?-Adduct (Trans)formations in Heteroaromatic Systems1

    OpenAIRE

    Zimnicka, Magdalena; Danikiewicz, Witold

    2015-01-01

    Anions of nitroderivatives of thiophene and furan were subjected to the reactions with selected C-H acids in the gas phase. Various structures and reaction pathways were proposed for the observed ionic products. In general, the reactions of heteroaromatic anions with C-H acids may be divided into three groups, depending on the proton affinity difference between C-H acid?s conjugate base and heteroaromatic anion (?PA). The proton transfer from C-H acid to heteroaromatic anion is a dominant pro...

  3. Measurement of weak radioactivity

    CERN Document Server

    Theodorsson , P

    1996-01-01

    This book is intended for scientists engaged in the measurement of weak alpha, beta, and gamma active samples; in health physics, environmental control, nuclear geophysics, tracer work, radiocarbon dating etc. It describes the underlying principles of radiation measurement and the detectors used. It also covers the sources of background, analyzes their effect on the detector and discusses economic ways to reduce the background. The most important types of low-level counting systems and the measurement of some of the more important radioisotopes are described here. In cases where more than one type can be used, the selection of the most suitable system is shown.

  4. TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

    Directory of Open Access Journals (Sweden)

    Marta Ziemnicka-Sylwester

    2013-05-01

    Full Text Available TiB2-based ceramic matrix composites (CMCs were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS was carried out for the highly exothermic “in situ” reaction of TiB2 formation and the “tailing” synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB2 vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB2:B4C molar ratio of 0.96, which corresponds to 40 vol% of TiB2 in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB2:B4C molar ratio of 2.16 or above. Finally B13C2 was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB2 grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure, were obtained for material containing 80 vol% of TiB2, fabricated using a graphite precursor of 2 μm.

  5. TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

    Science.gov (United States)

    Ziemnicka-Sylwester, Marta

    2013-01-01

    TiB2-based ceramic matrix composites (CMCs) were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic “in situ” reaction of TiB2 formation and the “tailing” synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB2 vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB2:B4C molar ratio of 0.96, which corresponds to 40 vol% of TiB2 in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB2:B4C molar ratio of 2.16 or above. Finally B13C2 was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB2 grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure), were obtained for material containing 80 vol% of TiB2, fabricated using a graphite precursor of 2 μm. PMID:28809250

  6. ICU-Acquired Weakness.

    Science.gov (United States)

    Jolley, Sarah E; Bunnell, Aaron E; Hough, Catherine L

    2016-11-01

    Survivorship after critical illness is an increasingly important health-care concern as ICU use continues to increase while ICU mortality is decreasing. Survivors of critical illness experience marked disability and impairments in physical and cognitive function that persist for years after their initial ICU stay. Newfound impairment is associated with increased health-care costs and use, reductions in health-related quality of life, and prolonged unemployment. Weakness, critical illness neuropathy and/or myopathy, and muscle atrophy are common in patients who are critically ill, with up to 80% of patients admitted to the ICU developing some form of neuromuscular dysfunction. ICU-acquired weakness (ICUAW) is associated with longer durations of mechanical ventilation and hospitalization, along with greater functional impairment for survivors. Although there is increasing recognition of ICUAW as a clinical entity, significant knowledge gaps exist concerning identifying patients at high risk for its development and understanding its role in long-term outcomes after critical illness. This review addresses the epidemiologic and pathophysiologic aspects of ICUAW; highlights the diagnostic challenges associated with its diagnosis in patients who are critically ill; and proposes, to our knowledge, a novel strategy for identifying ICUAW. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2012-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-01

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

  9. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

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

  10. Advancements in Anion Exchange Membrane Cations

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  11. Fluorescence quenching of etilefrine by acetate anion

    Science.gov (United States)

    Quintero Osso, B.; Carazo Rodríguez, F. M.; Morales Domingo, J. J.; Cabeza González, M. C.; Thomas Gómez, J.

    1999-02-01

    Acid dissociation in the excited state of antihypotensor drug etilefrine [2-(ethylamino1-3-hydroxyphenyl)ethanol] is studied. Fluorescence of etilefrine decreases at pH7. Analyses of the absorption and fluorescence spectra of aqueous solutions of etilefrine in the presence of acetate anions have been made. Considering the existence of an equilibrium in the excited state the values of 3.47×10 -9 and 0.216×10 -9 M -1 s -1 have been obtained for the rate constants for direct and inverse reactions, respectively. Moreover, the lifetime ( τ0'=0.58×10 -9 s) and quantum yield (0.01) of non-protonated etilefrine have been determined. Our results seem to support the existence of a dynamic quenching process based on a proton transfer mechanism induced by acetate anions. This process could represent a serious inconvenience in analytical fluorimetric techniques taking into account that the acetic acid/acetate pair is commonly used as a buffer. Additional fluorescence quenching by H + ions could be involved in acid aqueous mediums. At high concentrations of acetic acid, a value of 2.98×10 -9 M -1 s -1 for the bimolecular constant for the quenching by H + has been calculated.

  12. Sorptive separation of yttrium and cerium on a weakly basic anionite

    Science.gov (United States)

    Cheremisina, O. V.; Ponomareva, M. A.; Chirkst, D. E.; Lobacheva, O. L.; Shul'gin, I. A.

    2015-01-01

    The sorption of complex yttrium ions with Trilon B onto the weakly basic anionite D-403 in nitrate form from an acidic medium at pH 3 with constant ionic strength (NaNO3, 1 mol/kg) is investigated. A thermodynamic evaluation of the sorption isotherm of anionic yttrium complexes is performed using a method based on the linearization of the equation of the law of active mass, modified for ionic exchange reactions. The ionic exchange constant, the Gibbs free energy of ionic exchange, the capacity of the anionite, and the sorption limit of ethylenediaminetetraacetatoyttrate ions (EDTA yttrate ions) are calculated. Using a frontal version of ion exchange chromatography, cerium and yttrium are separated on D-403 anionite with a fraction of pure yttrium at the column outlet of no less than 30%.

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

    KAUST Repository

    Figueira, Flávio

    2016-12-02

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

  14. Weak Quantum Ergodicity

    CERN Document Server

    Kaplan, L

    1998-01-01

    We examine the consequences of classical ergodicity for the localization properties of individual quantum eigenstates in the classical limit. We note that the well known Schnirelman result is a weaker form of quantum ergodicity than the one implied by random matrix theory. This suggests the possibility of systems with non-gaussian random eigenstates which are nonetheless ergodic in the sense of Schnirelman and lead to ergodic transport in the classical limit. These we call "weakly quantum ergodic.'' Indeed for a class of "slow ergodic" classical systems, it is found that each eigenstate becomes localized to an ever decreasing fraction of the available state space, in the semiclassical limit. Nevertheless, each eigenstate in this limit covers phase space evenly on any classical scale, and long-time transport properties betwen individual quantum states remain ergodic due to the diffractive effects which dominate quantum phase space exploration.

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

    NARCIS (Netherlands)

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

    1997-01-01

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

  16. Preparation of a novel weak cation exchange/hydrophobic interaction chromatography dual-function polymer-based stationary phase for protein separation using "thiol-ene click chemistry".

    Science.gov (United States)

    Yang, Fan; Bai, Quan; Zhao, Kailou; Gao, Dong; Tian, Lei

    2015-02-01

    A novel dual-function mixed-mode stationary phase based on poly(glycidyl methacrylate-co-ethylene dimethacrylate) microspheres was synthesized by thiol-ene click chemistry and characterized by infrared spectroscopy and elemental analysis. The new system displays both hydrophobic interaction chromatography (HIC) character in a high salt concentration mobile phase, and weak cation exchange (WCX) chromatography character in a low salt concentration mobile phase. It can be used to separate proteins in both ion-exchange chromatography (IEC) mode and HIC mode. The resolution and selectivity of the stationary phase were evaluated in both HIC mode and IEC mode using protein standards. In comparison with the conventional WCX and HIC columns, the results were satisfactory and acceptable. Protein mass and bioactivity recoveries of more than 96% can be achieved in both HIC mode and IEC mode using this column. The results indicate that the novel dual-function mixed-mode column in many cases can replace the use of two individual WCX and HIC columns. In addition, the effects on protein separation of different ligand structures in the dual-function stationary phase and the pH of the mobile phase used were also investigated in detail. The results show that electrostatic interaction of the ligand with proteins must match the hydrophobicity of the ligand, which is an important factor to prepare the dual-function stationary phase. On the basis of this dual-function mixed-mode chromatography column, a new two-dimensional liquid chromatography technology with a single column system was also developed in this study, and was used to renature and purify recombinant human interferon-γ from inclusion bodies. The mass recovery, purity, and specific bioactivity obtained for the purified recombinant human interferon-γ were 87.2%, 92.4%, and 2.8 × 10(7) IU/mg, respectively, in IEC mode, and 83.4%, 95.2%, and 4.3 × 10(7) IU/mg, respectively, in HIC mode. The results indicate that the

  17. Interstellar Anions: The Role of Quantum Chemistry.

    Science.gov (United States)

    Fortenberry, Ryan C

    2015-10-01

    Six anions have been conclusively detected in the interstellar medium (ISM). They all arrived within a five-year window ending five years ago. Why have no new anions been detected? It is likely a lack of laboratory data for novel anions. This work reviews the role that valence and dipole-bound excited states may play in the formation, detection, and lifetime of anions that may yet be observed in the ISM and how quantum chemistry enhances this understanding. The list of interstellar anions has certainly not been exhausted by any means, but electronic, spectroscopic, and structural data must be provided to aid in any future detections. Quantum chemistry has the flexibility and completeness to provide a full picture of these systems and has shown exceptional accuracies of late. The work reviewed herein gives an overview of what quantum chemical computations have produced and will continue to provide related to anions and how this will enhance both laboratory experiment and astronomical observation.

  18. Changing certain dietary cationic and anionic minerals: Impact on ...

    African Journals Online (AJOL)

    This study was conducted to examine the influence of varying dietary cation anion difference (DCAD) on acid base status, mineral dynamics, occurrence of milk fever and udder edema in Nili Ravi buffaloes in a randomized complete block design. Four iso-nitrogenous and iso-caloric diets having -22, -11, +11 and +22 ...

  19. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

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

  20. Quadriceps weakness and osteoarthritis of the knee.

    Science.gov (United States)

    Slemenda, C; Brandt, K D; Heilman, D K; Mazzuca, S; Braunstein, E M; Katz, B P; Wolinsky, F D

    1997-07-15

    The quadriceps weakness commonly associated with osteoarthritis of the knee is widely believed to result from disuse atrophy secondary to pain in the involved joint. However, quadriceps weakness may be an etiologic factor in the development of osteoarthritis. To explore the relation between lower-extremity weakness and osteoarthritis of the knee. Cross-sectional prevalence study. Population-based, with recruitment by random-digit dialing. 462 volunteers 65 years of age or older. Radiographs of the knee were graded for the presence of osteoarthritis. Knee pain and function were assessed with the Western Ontario and McMaster Universities Arthritis Index, the strength of leg flexors and extensors was assessed with isokinetic dynamometry, and lower-extremity lean tissue mass was assessed with dual-energy x-ray absorptiometry. Among participants with osteoarthritis, quadriceps weakness, but not hamstring weakness, was common. The ratio of extensor strength to body weight was approximately 20% lower in those with than in those without radiographic osteoarthritis. Notably, among women with tibiofemoral osteoarthritis, extensor weakness was present in the absence of knee pain and was seen in participants with normal lower-extremity lean mass (extensor strength, 30.1 lb-ft for those with osteoarthritis and 34.8 lb-ft for those without osteoarthritis; P osteoarthritis of the knee (odds ratio for prevalence of osteoarthritis per 10 lb-ft loss of strength, 0.8 [95% CI, 0.71 to 0.90] for radiographic osteoarthritis and 0.71 [CI, 0.51 to 0.87] for symptomatic osteoarthritis). Quadriceps weakness may be present in patients who have osteoarthritis but do not have knee pain or muscle atrophy; this suggests that the weakness may be due to muscle dysfunction. The data are consistent with the possibility that quadriceps weakness is a primary risk factor for knee pain, disability, and progression of joint damage in persons with osteoarthritis of the knee.

  1. Ring-opening metathesis polymerization-derived monolithic anion exchangers for the fast separation of double-stranded DNA fragments.

    Science.gov (United States)

    Lubbad, Said H; Buchmeiser, Michael R

    2011-04-29

    Ring-opening metathesis polymerization- (ROMP) derived monoliths were prepared from 5-norborn-2-enemethyl bromide (NBE-CH(2)Br) and tris(5-norborn-2-enemethoxy)methylsilane ((NBE-CH(2)O)(3)SiCH(3)) within the confines of surface-silanized borosilicate columns (100×3 mm I.D.), applying Grubbs' first generation benzylidene-type catalyst [RuCl(2)(PCy(3))(2)(CHPh)]. Monoliths were converted into weak anion exchangers via reaction with diethyl amine. The resulting monolithic anion exchangers demonstrated a very good potential for the anion-exchange separation of nucleic acids applying a phosphate buffer (0.05 mol/L, pH 7) and NaCl (1.0 mol/L) as a gradient former. Fast and efficient separations, indicated by sharp and highly symmetric analyte peaks, were established. Except for the 267 and 298 base pair fragments, the eleven fragments of a ds-pUC18 DNA Hae III digest were baseline separated within ∼8 min. Nineteen fragments of a ds-pBR322 Hae III digest were separated within ∼12 min. There, only the 192 and 213 base pair fragments and the 458, 504 and 540 base pair fragments coeluted. A ds-pUC18 DNA Hae III digest was used as a control analyte in evaluating the influence of organic additives on the mobile phase such as methanol and acetonitrile on nucleic acid separation. Methanol, and even better, acetonitrile improved the separation efficiency and shortened the analysis time. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Spare optimistic based on improved ADMM and the minimum entropy de-convolution for the early weak fault diagnosis of bearings in marine systems.

    Science.gov (United States)

    Gao, Yangde; Karimi, Mohammad; Kudreyko, Aleksey A; Song, Wanqing

    2017-12-30

    In the marine systems, engines represent the most important part of ships, the probability of the bearings fault is the highest in the engines, so in the bearing vibration analysis, early weak fault detection is very important for long term monitoring. In this paper, we propose a novel method to solve the early weak fault diagnosis of bearing. Firstly, we should improve the alternating direction method of multipliers (ADMM), structure of the traditional ADMM is changed, and then the improved ADMM is applied to the compressed sensing (CS) theory, which realizes the sparse optimization of bearing signal for a mount of data. After the sparse signal is reconstructed, the calculated signal is restored with the minimum entropy de-convolution (MED) to get clear fault information. Finally we adopt the sample entropy. Morphological mean square amplitude and the root mean square (RMS) to find the early fault diagnosis of bearing respectively, at the same time, we plot the Boxplot comparison chart to find the best of the three indicators. The experimental results prove that the proposed method can effectively identify the early weak fault diagnosis. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  3. DWDM channel spacing tunable optical TDM carrier from a mode-locked weak-resonant-cavity Fabry-Perot laser diode based fiber ring.

    Science.gov (United States)

    Peng, Guo-Hsuan; Chi, Yu-Chieh; Lin, Gong-Ru

    2008-08-18

    A novel optical TDM pulsed carrier with tunable mode spacing matching the ITU-T defined DWDM channels is demonstrated, which is generated from an optically injection-mode-locked weak-resonant-cavity Fabry-Perot laser diode (FPLD) with 10%-end-facet reflectivity. The FPLD exhibits relatively weak cavity modes and a gain spectral linewidth covering >33.5 nm. The least common multiple of the mode spacing determined by both the weak-resonant-cavity FPLD and the fiber-ring cavity can be tunable by adjusting length of the fiber ring cavity or the FPLD temperature to approach the desired 200GHz DWDM channel spacing of 1.6 nm. At a specific fiber-ring cavity length, such a least-common- multiple selection rule results in 12 lasing modes between 1532 and 1545 nm naturally and a mode-locking pulsewidth of 19 ps broadened by group velocity dispersion among different modes. With an additional intracavity bandpass filter, the operating wavelength can further extend from 1520 to 1553.5 nm. After channel filtering, each selected longitudinal mode gives rise to a shortened pulsewidth of 12 ps due to the reduced group velocity dispersion. By linear dispersion compensating with a 55-m long dispersion compensation fiber (DCF), the pulsewidth can be further compressed to 8 ps with its corresponding peak-to-peak chirp reducing from 9.7 to 4.3 GHz.

  4. Evaluation of FRP Confinement Models for Substandard Rectangular RC Columns Based on Full-Scale Reversed Cyclic Lateral Loading Tests in Strong and Weak Directions

    Directory of Open Access Journals (Sweden)

    Hamid Farrokh Ghatte

    2016-09-01

    Full Text Available Although many theoretical and experimental studies are available on external confinement of columns using fiber-reinforced polymer (FRP jackets, as well as numerous models proposed for the axial stress-axial strain relation of concrete confined with FRP jackets, they have not been validated with a sufficient amount and variety of experimental data obtained through full-scale tests of reinforced concrete (RC columns with different geometrical and mechanical characteristics. Particularly, no systematical experimental data have been presented on full-scale rectangular substandard RC columns subjected to reversed cyclic lateral loads along either their strong or weak axes. In this study, firstly, test results of five full-scale rectangular substandard RC columns with a cross-sectional aspect ratio of two (300 mm × 600 mm are briefly summarized. The columns were tested under constant axial load and reversed cyclic lateral loads along their strong or weak axes before and after retrofitting with external FRP jackets. In the second stage, inelastic lateral force-displacement relationships of the columns are obtained analytically, making use of the plastic hinge assumption and different FRP confinement models available in the literature. Finally, the analytical findings are compared with the test results for both strong and weak directions of the columns. Comparisons showed that use of different models for the stress-strain relationship of FRP-confined concrete can yield significantly non-conservative or too conservative retrofit designs, particularly in terms of deformation capacity.

  5. A polyacrylamide-based silica stationary phase for the separation of carbohydrates using alcohols as the weak eluent in hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Cai, Jianfeng; Cheng, Lingping; Zhao, Jianchao; Fu, Qing; Jin, Yu; Ke, Yanxiong; Liang, Xinmiao

    2017-11-17

    A hydrophilic interaction liquid chromatography (HILIC) stationary phase was prepared by a two-step synthesis method, immobilizing polyacrylamide on silica sphere particles. The stationary phase (named PA, 5μm dia) was evaluated using a mixture of carbohydrates in HILIC mode and the column efficiency reached 121,000Nm -1 . The retention behavior of carbohydrates on PA stationary phase was investigated with three different organic solvents (acetonitrile, ethanol and methanol) employed as the weak eluent. The strongest hydrophilicity of PA stationary phase was observed in both acetonitrile and methanol as the weak eluent, when compared with another two amide stationary phases. Attributing to its high hydrophilicity, three oligosaccharides (xylooligosaccharide, fructooligosaccharide and chitooligosaccharides) presented good retention on PA stationary phase using alcohols/water as mobile phase. Finally, PA stationary phase was successfully applied for the purification of galactooligosaccharides and saponins of Paris polyphylla. It is feasible to use safer and cheaper alcohols to replace acetonitrile as the weak eluent for green analysis and purification of polar compounds on PA stationary phase. Copyright © 2017. Published by Elsevier B.V.

  6. SEM-based methods for the analysis of basaltic ash from weak explosive activity at Etna in 2006 and the 2007 eruptive crisis at Stromboli

    Science.gov (United States)

    Lautze, Nicole C.; Taddeucci, Jacopo; Andronico, Daniele; Cannata, Chiara; Tornetta, Lauretta; Scarlato, Piergiorgio; Houghton, Bruce; Lo Castro, Maria Deborah

    2012-01-01

    We present results from a semi-automated field-emission scanning electron microscope investigation of basaltic ash from a variety of eruptive processes that occurred at Mount Etna volcano in 2006 and at Stromboli volcano in 2007. From a methodological perspective, the proposed techniques provide relatively fast (about 4 h per sample) information on the size distribution, morphology, and surface chemistry of several hundred ash particles. Particle morphology is characterized by compactness and elongation parameters, and surface chemistry data are shown using ternary plots of the relative abundance of several key elements. The obtained size distributions match well those obtained by an independent technique. The surface chemistry data efficiently characterize the chemical composition, type and abundance of crystals, and dominant alteration phases in the ash samples. From a volcanological perspective, the analyzed samples cover a wide spectrum of relatively minor ash-forming eruptive activity, including weak Hawaiian fountaining at Etna, and lava-sea water interaction, weak Strombolian explosions, vent clearing activity, and a paroxysm during the 2007 eruptive crisis at Stromboli. This study outlines subtle chemical and morphological differences in the ash deposited at different locations during the Etna event, and variable alteration patterns in the surface chemistry of the Stromboli samples specific to each eruptive activity. Overall, we show this method to be effective in quantifying the main features of volcanic ash particles from the relatively weak - and yet frequent - explosive activity occurring at basaltic volcanoes.

  7. Political corruption and weak state

    Directory of Open Access Journals (Sweden)

    Stojiljković Zoran

    2013-01-01

    Full Text Available The author starts from the hypothesis that it is essential for the countries of the region to critically assess the synergy established between systemic, political corruption and a selectively weak, “devious” nature of the state. Moreover, the key dilemma is whether the expanded practice of political rent seeking supports the conclusion that the root of all corruption is in the very existence of the state - particularly in excessive, selective and deforming state interventions and benefits that create a fertile ground for corruption? The author argues that the destructive combination of weak government and rampant political corruption is based on scattered state intervention, while also rule the parties cartel in the executive branch subordinate to parliament, the judiciary and the police. Corrupt exchange takes place with the absence of strong institutional framework and the precise rules of the political and electoral games, control of public finances and effective political and anti-monopoly legislation and practice included. Exit from the current situation can be seen in the realization of effective anti­corruption strategy that integrates preventive and repressive measures and activities and lead to the establishment of principles of good governance. [Projekat Ministarstva nauke Republike Srbije, br. 179076: Politički identitet Srbije u regionalnom i globalnom kontekstu

  8. Zwitterionic, cationic, and anionic fluorinated chemicals in aqueous film forming foam formulations and groundwater from U.S. military bases by nonaqueous large-volume injection HPLC-MS/MS.

    Science.gov (United States)

    Backe, Will J; Day, Thomas C; Field, Jennifer A

    2013-05-21

    A new analytical method was developed to quantify 26 newly-identified and 21 legacy (e.g. perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and fluorotelomer sulfonates) per and polyfluorinated alkyl substances (PFAS) in groundwater and aqueous film forming foam (AFFF) formulations. Prior to analysis, AFFF formulations were diluted into methanol and PFAS in groundwater were micro liquid-liquid extracted. Methanolic dilutions of AFFF formulations and groundwater extracts were analyzed by large-volume injection (900 μL) high-performance liquid chromatography tandem mass spectrometry. Orthogonal chromatography was performed using cation exchange (silica) and anion exchange (propylamine) guard columns connected in series to a reverse-phase (C18) analytical column. Method detection limits for PFAS in groundwater ranged from 0.71 ng/L to 67 ng/L, and whole-method accuracy ranged from 96% to 106% for analytes for which matched authentic analytical standards were available. For analytes without authentic analytical standards, whole-method accuracy ranged from 78 % to 144 %, and whole-method precision was less than 15 % relative standard deviation for all analytes. A demonstration of the method on groundwater samples from five military bases revealed eight of the 26 newly-identified PFAS present at concentrations up to 6900 ng/L. The newly-identified PFAS represent a minor fraction of the fluorinated chemicals in groundwater relative to legacy PFAS. The profiles of PFAS in groundwater differ from those found in fluorotelomer- and electrofluorination-based AFFF formulations, which potentially indicates environmental transformation of PFAS.

  9. Synthesis, structure, and electronic structure calculation of a new centrosymmetric borate Pb{sub 2}O[BO{sub 2}(OH)] based on anion-centered OPb{sub 4} tetrahedra

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Feng [College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi 830054 (China); Wang, Li, E-mail: wangliresearch@163.com [College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi 830054 (China); Stoumpos, Constantinos C. [Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States)

    2016-08-15

    The synthesis, structure, and characterization of a new centrosymmetric borate Pb{sub 2}O[BO{sub 2}(OH)] based on anion-centered OPb{sub 4} tetrahedra are reported. Pb{sub 2}O[BO{sub 2}(OH)] crystallizes in monoclinic space group C2/m with a=12.725(7) Å, b=5.698(3) Å, c=7.344(4) Å, β=116.277(6)°. The electronic band structure and density of states of Pb{sub 2}O[BO{sub 2}(OH)] have been calculated via the density functional theory (DFT). Electron density difference calculation indicates that lone-pair electrons of Pb{sup 2+} cation should be stereoactive. - Graphical abstract: An indirect gap compound of Pb{sub 2}O[BO{sub 2}(OH)] with 2D inorganic layers motif based on OPb{sub 4} tetrahedra has been synthesized and full characterized by crystallographic, IR, TG, UV–vis-NIR Diffuse Reflectance, and theoretical calculations. Display Omitted - Highlights: • A centrosymmetric borate Pb{sub 2}O[BO{sub 2}(OH)] was synthesized and characterized. • The crystalstructure, electronic band and density states was analyzed. • The lone-pair electrons of Pb{sup 2+} were proved to be stereoactive.

  10. Yeast adaptation to weak acids prevents futile energy expenditure

    Science.gov (United States)

    Ullah, Azmat; Chandrasekaran, Gayathri; Brul, Stanley; Smits, Gertien J.

    2013-01-01

    Weak organic acids (WOAs) are widely used preservatives to prevent fungal spoilage of foods and beverages. Exposure of baker's yeast Saccharomyces cerevisiae to WOA leads to cellular acidification and anion accumulation. Pre-adaptation of cultures reduced the rate of acidification caused by weak acid exposure, most likely as a result of changes in plasma membrane or cell wall composition. In order to adapt to sublethal concentrations of the acids and grow, yeast cells activate ATP consuming membrane transporters to remove protons and anions. We explored to what extent ATP depletion contributes to growth inhibition in sorbic or acetic acid treated cells. Therefore, we analyzed the effect of the reduction of proton and anion pumping activity on intracellular pH (pHi), growth, and energy status upon exposure to the hydrophilic acetic acid (HA) and the lipophilic sorbic acid (HS). ATP concentrations were dependent on the severity of the stress. Unexpectedly, we observed a stronger reduction of ATP with growth reducing than with growth inhibitory concentrations of both acids. We deduce that the not the ATP reduction caused by proton pumping, but rather the cost of sorbate anion pumping contributes to growth inhibition. A reduction of proton pumping activity may reduce ATP consumption, but the resulting decrease of pHi affects growth more. ATP utilization was differentially regulated during moderate and severe stress conditions. We propose that the energy depletion alone is not the cause of growth inhibition during HA or HS stress. Rather, the cells appear to reduce ATP consumption in high stress conditions, likely to prevent futile cycling and maintain energy reserves for growth resumption in more favorable conditions. The mechanism for such decision making remains to be established. PMID:23781215

  11. Yeast adaptation to weak acids prevents futile energy expenditure

    Directory of Open Access Journals (Sweden)

    Azmat eUllah

    2013-06-01

    Full Text Available Weak organic acids (WOA are widely used preservatives to prevent fungal spoilage of foods and beverages. Exposure of baker’s yeast Saccharomyces cerevisiae to WOA leads to cellular acidification and anion accumulation. Pre-adaptation of cultures reduced the rate of acidification caused by weak acid exposure, most likely as a result of changes in plasma membrane or cell wall composition. In order to adapt to sublethal concentrations of the acids and grow, yeast cells activate ATP consuming membrane transporters to remove protons and anions. We explored to what extent ATP depletion contributes to growth inhibition in sorbic or acetic acid treated cells. Therefore, we analyzed the effect of the reduction of proton and anion pumping activity on intracellular pH (pHi, growth, and energy status upon exposure to the hydrophilic acetic acid (HA and the lipophilic sorbic acid (HS. ATP concentrations were dependent on the severity of the stress. Unexpectedly, we observed a stronger reduction of ATP with growth reducing than with growth inhibitory concentrations of both acids. We deduce that the not the ATP reduction caused by proton pumping, but rather the cost of sorbate anion pumping contributes to growth inhibition. A reduction of proton pumping activity may reduce ATP consumption, but the resulting decrease of intracellular pH affects growth more. ATP utilization was differentially regulated during moderate and severe stress conditions. We propose that the energy depletion alone is not the cause of growth inhibition during HA or HS stress. Rather, the cells appear to reduce ATP consumption in high stress conditions, likely to prevent futile cycling and maintain energy reserves for growth resumption in more favorable conditions. The mechanism for such decision making remains to be established.

  12. New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

    NARCIS (Netherlands)

    Chubar, N.

    2011-01-01

    New inorganic ion exchangers based on double Mg–Al hydrous oxides were generated via the new non-traditional sol–gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and

  13. Dissolution of anionic surfactant mesophases.

    Science.gov (United States)

    Poulos, Andreas S; Jones, Christopher S; Cabral, João T

    2017-08-09

    Linear and circular solvent penetration experiments are used to study the dissolution of anionic SLE3S surfactant mesophases in water. We show that a lamellar (Lα) phase in contact with water will transit through a series of cubic, hexagonal, and micellar phase bands with sharp interfaces identified from their optical textures. In both linear and circular geometries, the kinetics of front propagation and eventual dissolution are well described by diffusive penetration of water, and a simple model applies to both geometries, with a different effective diffusion coefficient for water Df as the only fitting parameter. Finally, we show a surprising variation of dissolution rates with initial surfactant concentration that can be well explained by assuming that the driving force for solvent penetration is the osmotic pressure difference between neat water and the aqueous fraction of the mesophase that is highly concentrated in surfactant counterions.

  14. Spectrophotometric Determination of Selenium Through Triiodide Anion.

    Science.gov (United States)

    Bizerea-Spiridon, Otilia; Nartita, Radu; Rogobete, Alexandru F; Negrea, Adina; Stroescu, Ramona; Bizerea, Teofana O; Ilie, Constantin; Marginean, Otilia

    2017-05-01

    Selenium is a chemical element found in the human body that plays a crucial role in its regulation. Depending on the concentration, it may have beneficial or have toxic effects. Selenium is incorporated as selenocysteine amino acid residue in selenoproteins which play an important role in many biological functions: anti-oxidant defense, regulation of the immune function and of the inflammatory response, metabolism of thyroid hormones, functioning of the central nervous system, biosynthesis of DNA and RNA, fertility, and reproduction. Excess selenium, altough less common than selenium deficiency, has equally important negative effects. Given the importance of selenium quantification in various samples, the study proposes a simple and direct spectrophotometric determination of selenium using triiodide anions. The method is based on the oxidation of iodide in acidic medium by selenium (IV) contained in the sample, to form elemental iodine which, in turn, reacts with the excess iodide to form the triiodide anions, the most stable soluble species in aqueous solution. Triiodide is colored from yellow to brown, depending on the concentration. The coloured compound has maximum absorbance at specific wavelengths and thus, the stage of interaction with a chromogenic agent is eliminated. Due to the sensitivity of the reaction, the detection limit of triiodide, and therefore selenium, is extended toward lower values. The optimal conditions for the measurements were established: λ = 290 nm, pH = 1.0 - 1.5, reaction time = 15 minutes. Two areas of selenium detection were determined from the samples: 0.025 - 0.100 ppm, and 0.1 - 4.0 ppm. The detection limit of selenium was lowered at 0.100 ppm and even at 0.025 ppm, which significantly improves the sensitivity of the determination. Types of samples were specified which are suitable for analysis using the proposed method and explained why, in case of biological fluids, it must be used only accompanied by an adequate digestion

  15. A Comparative Study of Enantioseparations of Nα-Fmoc Proteinogenic Amino Acids on Quinine-Based Zwitterionic and Anion Exchanger-Type Chiral Stationary Phases under Hydro-Organic Liquid and Subcritical Fluid Chromatographic Conditions

    Directory of Open Access Journals (Sweden)

    Gyula Lajkó

    2016-11-01

    Full Text Available The focus of this contribution is a comparative investigation of enantioseparations of 19 Nα-Fmoc proteinogenic amino acids on Quinine-based zwitterionic and anion-exchanger type chiral stationary phases employing hydro-organic and polar-ionic liquid and subcritical fluid chromatographic conditions. Effects of mobile phase composition (including additives, e.g., water, basis and acids and nature of chiral selectors on the chromatographic performances were studied at different chromatographic modes. Thermodynamic parameters of the temperature dependent enantioseparation results were calculated in the temperature range 5–50 °C applying plots of lnα versus 1/T. The differences in standard enthalpy and standard entropy for a given pair of enantiomers were calculated and served as a basis for comparisons. Elution sequence in all cases was determined, where a general rule could be observed, both in liquid and subcritical fluid chromatographic mode the d-enantiomers eluted before the L ones. In both modes, the principles of ion exchange chromatography apply.

  16. A Comparative Study of Enantioseparations of Nα-Fmoc Proteinogenic Amino Acids on Quinine-Based Zwitterionic and Anion Exchanger-Type Chiral Stationary Phases under Hydro-Organic Liquid and Subcritical Fluid Chromatographic Conditions.

    Science.gov (United States)

    Lajkó, Gyula; Grecsó, Nóra; Tóth, Gábor; Fülöp, Ferenc; Lindner, Wolfgang; Péter, Antal; Ilisz, István

    2016-11-22

    The focus of this contribution is a comparative investigation of enantioseparations of 19 Nα-Fmoc proteinogenic amino acids on Quinine-based zwitterionic and anion-exchanger type chiral stationary phases employing hydro-organic and polar-ionic liquid and subcritical fluid chromatographic conditions. Effects of mobile phase composition (including additives, e.g., water, basis and acids) and nature of chiral selectors on the chromatographic performances were studied at different chromatographic modes. Thermodynamic parameters of the temperature dependent enantioseparation results were calculated in the temperature range 5-50 °C applying plots of lnα versus 1/T. The differences in standard enthalpy and standard entropy for a given pair of enantiomers were calculated and served as a basis for comparisons. Elution sequence in all cases was determined, where a general rule could be observed, both in liquid and subcritical fluid chromatographic mode the d-enantiomers eluted before the L ones. In both modes, the principles of ion exchange chromatography apply.

  17. Effect of cation structure on the oxygen solubility and diffusivity in a range of bis{(trifluoromethyl)sulfonyl}imide anion based ionic liquids for lithium-air battery electrolytes.

    Science.gov (United States)

    Neale, Alex R; Li, Peilin; Jacquemin, Johan; Goodrich, Peter; Ball, Sarah C; Compton, Richard G; Hardacre, Christopher

    2016-04-28

    This paper reports on the solubility and diffusivity of dissolved oxygen in a series of ionic liquids (ILs) based on the bis{(trifluoromethyl)sulfonyl}imide anion with a range of related alkyl and ether functionalised cyclic alkylammonium cations. Cyclic voltammetry has been used to observe the reduction of oxygen in ILs at a microdisk electrode and chronoamperometric measurements have then been applied to simultaneously determine both the concentration and the diffusion coefficient of oxygen in different ILs. The viscosity of the ILs and the calculated molar volume and free volume are also reported. It is found that, within this class of ILs, the oxygen diffusivity generally increases with decreasing viscosity of the neat IL. An inverse relationship between oxygen solubility and IL free volume is reported for the two IL families implying that oxygen is not simply occupying the available empty space. In addition, it is reported that the introduction of an ether-group into the IL cation structure promotes the diffusivity of dissolved oxygen but reduces the solubility of the gas.

  18. Speciation analysis of calcium, iron, and zinc in casein phosphopeptide fractions from toddler milk-based formula by anion exchange and reversed-phase high-performance liquid chromatography-mass spectrometry/flame atomic-absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miquel, Esther; Alegria, Amparo; Barbera, Reyes; Farre, Rosaura [University of Valencia, Nutrition and Food Chemistry, Faculty of Pharmacy, Burjassot, Valencia (Spain)

    2005-03-01

    Casein phosphopeptides (CPP) are phosphorylated casein-derived peptides that can be released by in-vitro or in-vivo enzymatic hydrolysis of {alpha}{sub s1}-casein, {alpha}{sub s2}-casein, and {beta}-casein (CN). Many of these peptides contain a highly polar acidic sequence of three phosphoseryl groups followed by two glutamic acid residues. These domains are binding sites for minerals such as calcium, iron, and zinc and play an important role in mineral bioavailability. The aim of this study was speciation analysis of calcium, iron, and zinc in CPP fractions from the soluble fraction of a toddler milk-based formula. Methods for CPP separation by anion-exchange high-performance liquid chromatography (AE-HPLC) were combined with CPP identification by reversed-phase high performance liquid chromatography-electrospray ionization mass spectrometry and determination of the calcium, iron, zinc, and phosphorus content of the fractions obtained by AE-HPLC. Calcium and phosphorus were detected in all the analyzed AE-HPLC fractions. Calcium and zinc could be bound to CPP derived from {alpha}{sub s1}-CN and {alpha}{sub s2}-CN in fraction 3. Iron could be bound to CPP in fraction 4 in which {beta}-CN(15-34)4P was present with the cluster sequence S(P)S(P)S(P)EE. The results obtained prove the different distribution of calcium, iron, and zinc in heterogeneous CPP fractions. (orig.)

  19. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

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

  20. Neutral anion receptors: design and application

    NARCIS (Netherlands)

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

    1998-01-01

    After the development of synthetic cation receptors in the late 1960s, only in the past decade has work started on the development of synthetic neutral anion receptors. Combination and preorganization of different anion binding groups, like amides, urea moieties, or Lewis acidic metal centers lead

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

    Science.gov (United States)

    Aydoğan, Cemil

    2015-05-01

    In this study, an anion-exchange/hydrophobic polymethacrylate-based stationary phase was prepared for nano-liquid chromatography of small organic molecules and inorganic anions. The stationary phase was synthesized by in situ polymerization of 3-chloro-2-hydroxypropylmethacrylate and ethylene dimethacrylate inside silanized 100 μm i.d. fused silica capillary. The porogen mixture consisted of toluene and dodecanol. The pore size distrubution profiles of the resulting monolith were determined by mercury intrusion porosimetry and the morphology of the prepared monolith was investigated by scanning electron microscope. Good permeability, stability and column efficiency were observed on the monolithic column with nano flow. The produced monolithic column, which contains reactive chloro groups, was then modified by reaction with N,N-dimethyl-N-dodecylamine to obtain an anion-exchange/hydrophobic monolithic stationary phase. The functionalized monolith contained ionizable amine groups and hydrophobic groups that are useful of anion-exchange/hydrophobic mixed-mode chromatography. The final monolithic column performance with respect to anion-exchange and hydrophobic interactions was assesed by the separation of alkylbenzene derivatives, phenolic compounds and inorganic anions, respectively. Theoretical plate numbers up to 23,000 plates/m were successfully achieved in the separation of inorganic anions. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

    Directory of Open Access Journals (Sweden)

    Ajit Kumar Mahapatra

    2010-02-01

    Full Text Available A novel indolocarbazole-based chemosensor 1 containing hydrogen bond donor moieties has been established as a selective colorimetric and fluorometric sensor for F− in CH3CN/H2O (4:1 v/v. Upon the addition of a series of tetrabutylammonium salts to receptor 1 in aqueous CH3CN, only when the counter ion was F− was a significant color change (from light violet to dark orange observed.

  3. Creating molecular macrocycles for anion recognition

    Directory of Open Access Journals (Sweden)

    Amar H. Flood

    2016-03-01

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

  4. Fungal growth on anion surfactant medium.

    Science.gov (United States)

    Hamada, Nobuo; Abe, Niichiro

    2009-12-01

    Before the present study, no fungi using anion surfactant as a nutrient had been identified, although some fungi were known to use nonion surfactant. Washing water collected from 63 washing machines was inoculated onto 0.1% LAS (Sodium dodecyl benzenesulfonate) anion surfactant media to identify fungi that can feed on anion-surfactant. Small dark colonies of fungi were found on several of the Petri-dishes from 12 days after inoculation. These were identified as Cladophialophora boppii and Exophiala spinifera using morphological features and rDNA data. A number of the isolates of C. boppii specifically were recognized as using anion surfactant as a nutrient. The growth characteristics of the two fungal species were examined on surfactant media of three kinds. Apart from anion surfactant, the fungi were also able to grow on nonion surfactant and on soap. The application of these fungi for environmental cleansing after detergent pollution is also discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-08-30

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

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

    Science.gov (United States)

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

    2011-01-30

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

  7. Inversion assuming weak scattering

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus

    2013-01-01

    due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...

  8. High-throughput investigation of single and binary protein adsorption isotherms in anion exchange chromatography employing multivariate analysis.

    Science.gov (United States)

    Field, Nicholas; Konstantinidis, Spyridon; Velayudhan, Ajoy

    2017-08-11

    The combination of multi-well plates and automated liquid handling is well suited to the rapid measurement of the adsorption isotherms of proteins. Here, single and binary adsorption isotherms are reported for BSA, ovalbumin and conalbumin on a strong anion exchanger over a range of pH and salt levels. The impact of the main experimental factors at play on the accuracy and precision of the adsorbed protein concentrations is quantified theoretically and experimentally. In addition to the standard measurement of liquid concentrations before and after adsorption, the amounts eluted from the wells are measured directly. This additional measurement corroborates the calculation based on liquid concentration data, and improves precision especially under conditions of weak or moderate interaction strength. The traditional measurement of multicomponent isotherms is limited by the speed of HPLC analysis; this analytical bottleneck is alleviated by careful multivariate analysis of UV spectra. Copyright © 2017. Published by Elsevier B.V.

  9. Weak Measurement and Quantum Correlation

    Indian Academy of Sciences (India)

    Arun Kumar Pati

    The concept of the weak measurements, for the first time, was introduced by Aharonov et al.1. Quantum state is preselected in |ψi〉 and allowed to interact weakly with apparatus. Measurement strength can be tuned and for “small g(t)” it is called 'weak measurement'. With postselection in |ψf 〉, apparatus state is shifted by an ...

  10. Weak C–H⋅⋅⋅F–C interactions in carboxylate anion binding ...

    Indian Academy of Sciences (India)

    Administrator

    ionic structures of both the complex salts having discrete ions along with lattice water molecules. .... atoms of water molecules were located from differ- ence Fourier map and were included in the refine- ment as riding hydrogen atoms. The residual electronic density was ...... Innovative Food, Health Products and Agriculture.

  11. Weak C–H⋅⋅⋅ F–C interactions in carboxylate anion binding ...

    Indian Academy of Sciences (India)

    5-fluorobenzoate; C-H…F interactions. ... Department of Chemistry, Panjab University, Chandigarh 160 014; Department of Chemistry, Faculty of Science, Chulalongkorn University, Phyathai Road, Pathumwan, Bangkok 10330, Thailand ...

  12. use of weak ion association in the separation of inorganic anions by ...

    African Journals Online (AJOL)

    a

    Box 2329, Dar es Salaam, Tanzania. 2Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushimanaka,. Okayama ... monitor levels of toxic or health endangering chemical species contained in water, foods and pharmaceuticals, constant ..... Inorganic Chemistry, Vol. 15, Wiley-Interscience: New York; ...

  13. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    Science.gov (United States)

    Ranke, Johannes; Othman, Alaa; Fan, Ping; Müller, Anja

    2009-01-01

    The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities. PMID:19399248

  14. Explaining ionic liquid water solubility in terms of cation and anion hydrophobicity.

    Science.gov (United States)

    Ranke, Johannes; Othman, Alaa; Fan, Ping; Müller, Anja

    2009-03-01

    The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

  15. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    Directory of Open Access Journals (Sweden)

    Johannes Ranke

    2009-03-01

    Full Text Available The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.

  16. Anionic Redox Chemistry in Polysulfide Electrode Materials for Rechargeable Batteries.

    Science.gov (United States)

    Grayfer, Ekaterina D; Pazhetnov, Egor M; Kozlova, Mariia N; Artemkina, Sofya B; Fedorov, Vladimir E

    2017-12-22

    Classical Li-ion battery technology is based on the insertion of lithium ions into cathode materials involving metal (cationic) redox reactions. However, this vision is now being reconsidered, as many new-generation electrode materials with enhanced reversible capacities operate through combined cationic and anionic (non-metal) reversible redox processes or even exclusively through anionic redox transformations. Anionic participation in the redox reactions is observed in materials with more pronounced covalency, which is less typical for oxides, but quite common for phosphides or chalcogenides. In this Concept, we would like to draw the reader's attention to this new idea, especially, as it applies to transition-metal polychalcogenides, such as FeS 2 , VS 4 , TiS 3 , NbS 3 , TiS 4 , MoS 3 , etc., in which the key role is played by the (S-S) 2- /2 S 2- redox reaction. The exploration and better understanding of the anion-driven chemistry is important for designing advanced materials for battery and other energy-related applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2017-10-09

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

  18. New method for the speciation of ruthenium-based chemotherapeutics in human serum by conjoint liquid chromatography on affinity and anion-exchange monolithic disks.

    Science.gov (United States)

    Martinčič, Anže; Milačič, Radmila; Vidmar, Janja; Turel, Iztok; Keppler, Bernhard K; Sčančar, Janez

    2014-12-05

    An important step in pharmacological characterisation of a candidate drug is the study of the drugs interactions with serum proteins. In the present work, conjoint liquid chromatography (CLC) was used for separation of ruthenium (Ru)-based drug candidates in human serum. CIM Protein G and CIM DEAE disks were assembled together in a single housing forming a CLC monolithic column. By applying isocratic elution with Tris-HCl-NaHCO3 buffer (pH 7.4) in the first min, followed by gradient elution with 1 mol L(-1) NH4Cl (pH 7.4) in the next 9 min, immunoglobulins (IgG) were retained by the Protein G disk enabling subsequent separation of unbound Ru species from Ru species bound to human serum transferrin (Tf) and albumin (HSA) on the CIM DEAE disk. Finally, elution with acetic acid (AcOH) in the next 3 min allowed separation of Ru species associated with IgG. Protein elution was followed on-line with UV detection at 278nm, while the separated Ru species were quantified by post-column isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). The instrumental set-up enabled fast two-dimensional separation by affinity and ion-exchange modes to be carried out in a single chromatographic run. Two Ru-based chemotherapeutics: a newly synthesised compound chlorido(η6-p-cymene)(nalidixicato-κ2O,O)Ru(II) (1) and (H2im)[trans-Ru(III)Cl4(Him)2] (2; KP418), which is currently undergoing preclinical studies, were investigated. The CLC procedure applied is sensitive with low limit of detection (LOD) (0.027 μg Ru mL(-1) for (1)) and good method repeatability (RSD±3.5%). The experimental data revealed that it enables investigation of the kinetics of interaction of positively charged and neutral complexes of metallodrugs with serum proteins as well as the distribution of metallodrug species in human serum. However, negatively charged metallic complexes co-eluted with Tf and HSA and thus hindered their speciation analysis. An example of successful application of the

  19. Heat integration of an ethanol polygeneration plant based on lignocellulose: Comparing weak acid hydrolysis and enzymatic hydrolysis; Energiintegrerat etanolkombinat baserat paa lignocellulosa - Jaemfoerelse mellan svagsyrahydrolys och enzymhydrolys

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Marcus; Nordman, Roger; Taherzadeh, Mohammad

    2011-07-01

    Plants for bioethanol production have been planned in several cities in Sweden, including Boraas. This report provides answers to general questions regarding how such a facility's energy demand is affected by the external integration with a heat and power plant and the internal energy integration between process units. Heat integration of a bioethanol plant means that energy is reused as much as is technically possible; this sets a practical minimum level for the energy demand of the plant. In the study, ethanol production from cellulose has been simulated using Aspen Plus. Weak acid hydrolysis and enzymatic hydrolysis have been simulated, each with 50,000 and 100,000 tonnes of ethanol per year, resulting in four simulation cases. In all cases, heat integration is evaluated using pinch analysis. The steam in the ethanol plant has been covered by steam from a heat and power plant similar to that found today in Boraas. It is important to note that the energy quotas reported here includes energy use for upgrading the residual products. This leads to lower energy quotas than would be the case if the upgrading of residuals were allocated outside of the ethanol production. The conclusions from the project are: - The steam demand of the ethanol plant leads to a reduction in both the electricity and heat production of the heat and power plant. For the weak acid hydrolysis, the electricity loss is relatively high, 26-98%, which will affect the revenue significantly. The loss of electricity production is lower for the enzymatic process: 11-47%. - The difference in decreased electricity between the theoretical case of heating the raw material and the two alternative heating cases is about a factor of two, so the design of the heating of raw material is extremely important. - The reduced heat output of the power plant can, in most cases, be balanced by the surplus heat from the ethanol plant, but to completely balance the shortage, heat over 100 deg C must be used

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

    Science.gov (United States)

    Sötz, Veronika Anna; Kochmann, Sven

    2015-05-01

    In this fundamental study, the simultaneous separation and detection of anions and thiophilic cations in anion exchange chromatography with suppressed conductivity detection is investigated. Mercury(II) and cadmium(II) served as model analytes. Separation and detection was performed by introducing 2-mercaptoethanesulfonate, which forms complexes with both mercury and cadmium with a strong metal-sulfur bond, into the KOH eluent. Additional to the separation on the column, these complexes were able to pass the suppressor. Subsequently, they could be detected as negative peaks. A simple model for the separation mechanism was developed based on these results. Furthermore, the effect of the eluent concentration on the retention factors of both cation complexes and standard anions was examined and quantified. It revealed that the concentration of 2-mercaptoethanesulfonate has more influence on the cations than the KOH concentration. Also, 2.0 mM of 2-mercaptoethanesulfonate had about the same effect on the anion separation as 60 mM KOH. Finally, selectivity and detection limits were investigated. The detection limits were 4.9 μM for mercury and 2.2 μM for cadmium. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Compósitos magnéticos baseados em hidrotalcitas para a remoção de contaminantes aniônicos em água Magnetic composites based on hydrotalcites for removal of anionic contaminants in water

    Directory of Open Access Journals (Sweden)

    Leandro da Conceição

    2007-10-01

    Full Text Available In this work the adsorption features of hydrotalcites (Al, Mg- CO3 and the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. These magnetic composites can be used as adsorbents for anionic contaminants in water and subsequently removed from the medium by a simple magnetic process. The magnetic hydrotalcites were characterized by XRD, magnetization measurements, N2 adsorption isotherms and Mössbauer spectroscopy. These magnetic adsorbents show remarkable adsorption capacity for anionic contaminants in water.

  2. Recent progress and applications of ion-exclusion/ion-exchange chromatography for simultaneous determination of inorganic anions and cations.

    Science.gov (United States)

    Nakatani, Nobutake; Kozaki, Daisuke; Mori, Masanobu; Tanaka, Kazuhiko

    2012-01-01

    One of the ultimate goals of ion chromatography is to determine both anions and cations found in samples with a single chromatographic run. In the present article, recent progress in ion-exclusion/ion-exchange chromatography for the simultaneous determinations of inorganic anions and cations are reviewed. Firstly, the principle and the control for the simultaneous separation and detection of analyte ions using ion-exclusion/cation-exchange chromatography with a weakly acidic cation-exchange column are outlined. Then, advanced chromatographic techniques in terms of analytical time, selectively and sensitivity are summarized. As a related method, ion-exclusion/anion-exchange chromatography with an anion-exchange column could be used for the simultaneous determination of inorganic nitrogen species, such as ammonium, nitrite and nitrate ions. Their usefulness and applications to water-quality monitoring and related techniques are also described.

  3. Strong managers, weak boards?

    OpenAIRE

    Renee B. Adams; Daniel Ferreira

    2009-01-01

    Many governance reform proposals are based on the view that boards have been too friendly to executives, for example, by awarding them excessive pay. Although boards are often on friendly terms with executives, it is less clear that they have systematically failed to function in the interests of shareholders. Understanding board monitoring requires a theory of boards that takes into account how firms provide incentives for their Chief Executive Officer's (CEOs) through other means. We develop...

  4. Understanding the interplay of weak forces in [3,3]-sigmatropic rearrangement for stereospecific synthesis of diamines.

    Science.gov (United States)

    So, Soon Mog; Mui, Leo; Kim, Hyunwoo; Chin, Jik

    2012-08-21

    Chiral diamines are important building blocks for constructing stereoselective catalysts, including transition metal based catalysts and organocatalysts that facilitate oxidation, reduction, hydrolysis, and C-C bond forming reactions. These molecules are also critical components in the synthesis of drugs, including antiviral agents such as Tamiflu and Relenza and anticancer agents such as oxaliplatin and nutlin-3. The diaza-Cope rearrangement reaction provides one of the most versatile methods for rapidly generating a wide variety of chiral diamines stereospecifically and under mild conditions. Weak forces such as hydrogen bonding, electronic, steric, oxyanionic, and conjugation effects can drive this equilibrium process to completion. In this Account, we examine the effect of these individual weak forces on the value of the equilibrium constant for the diaza-Cope rearrangement reaction using both computational and experimental methods. The availability of a wide variety of aldehydes and diamines allows for the facile synthesis of the diimines needed to study the weak forces. Furthermore, because the reaction generally takes place cleanly at ambient temperature, we can easily measure equilibrium constants for rearrangement of the diimines. We use the Hammett equation to further examine the electronic and oxyanionic effects. In addition, computations and experiments provide us with new insights into the origin and extent of stereospecificity for this rearrangement reaction. The diaza-Cope rearrangement, with its unusual interplay between weak forces and the equilibrium constant of the reaction, provides a rare opportunity to study the effects of the fundamental weak forces on a chemical reaction. Among these many weak forces that affect the diaza-Cope rearrangement, the anion effect is the strongest (10.9 kcal/mol) followed by the resonance-assisted hydrogen-bond effect (7.1 kcal/mol), the steric effect (5.7 kcal/mol), the conjugation effect (5.5 kcal/mol), and the

  5. Molecular anions sputtered from fluorides

    CERN Document Server

    Gnaser, H

    2002-01-01

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

  6. BVMO-catalysed dynamic kinetic resolution of racemic benzyl ketones in the presence of anion exchange resins

    NARCIS (Netherlands)

    Rodriguez, Cristina; de Gonzalo, Gonzalo; Rioz-Martinez, Ana; Pazmino, Daniel E. Torres; Fraaije, Marco W.; Gotor, Vicente

    2010-01-01

    4-Hydroxyacetophenone monooxygenase from Pseudomonas fluorescens ACB was employed in the presence of a weak anion exchange resin to perform dynamic kinetic resolutions of racemic benzyl ketones with high conversions and good optical purities. Different parameters that affect to the efficiency of the

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

    Science.gov (United States)

    Francis, Kevin; Gadda, Giovanni

    2009-10-01

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

  8. From Suitable Weak Solutions to Entropy Viscosity

    KAUST Repository

    Guermond, Jean-Luc

    2010-12-16

    This paper focuses on the notion of suitable weak solutions for the three-dimensional incompressible Navier-Stokes equations and discusses the relevance of this notion to Computational Fluid Dynamics. The purpose of the paper is twofold (i) to recall basic mathematical properties of the three-dimensional incompressible Navier-Stokes equations and to show how they might relate to LES (ii) to introduce an entropy viscosity technique based on the notion of suitable weak solution and to illustrate numerically this concept. © 2010 Springer Science+Business Media, LLC.

  9. Enhancing the basicity of ionic liquids by tuning the cation-anion interaction strength and via the anion-tethered strategy.

    Science.gov (United States)

    Xu, Dan; Yang, Qiwei; Su, Baogen; Bao, Zongbi; Ren, Qilong; Xing, Huabin

    2014-01-30

    Ionic liquids (ILs) with relatively strong basicity often show impressive performance in chemical processes, so it is important to enhance the basicity of ILs by molecular design. Here, we proposed two effective ways to enhance the basicity of ILs: by weakening the cation-anion interaction strength and by employing the anion-tethered strategy. Notably, two quantum-chemical parameters, the most negative surface electrostatic potential and the lowest surface average local ionization energy, were adopted as powerful tools to demonstrate the electrostatic and covalent aspects of basicity, respectively, at the microscopic level. It was shown that, for the ILs with the same anion (acetate or trifluoroacetate), the basicity of the ILs could be enhanced when the cation-anion interaction strength was weakened. For the acetate anion-based ILs, the hydrogen-bonding basicity scale (β) increased by 29% when the cation changed from 1-butyl-3-methylimidazolium ([Bmim]) to tetrabutylphosphonium ([P4444]), achieving one of the highest reported β values for ILs. Moreover, it was also demonstrated that, when an amine group was tethered to the anion of the IL, its basicity was stronger than when it was tethered to the cation. These results are highly instructive for designing ILs with strong basicity and for improving the efficiency of IL-based processes, such as CO2 capture, SO2 and acetylene absorption, dissolution of cellulose, extraction of bioactive compounds, and so on.

  10. Dynamics of anion-molecule reactions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikosch, J.

    2007-11-15

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

  11. Weak-Lensing Calibration of a Stellar Mass-Based Mass Proxy for redMaPPer and Voronoi Tessellation Clusters in SDSS Stripe 82

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Maria E.S. [Rio de Janeiro, CBPF; Soares-Santos, Marcelle [Fermilab; Makler, Martin [Rio de Janeiro, CBPF; Annis, James [Fermilab; Lin, Huan [Fermilab; Palmese, Antonella [Fermilab; Vitorelli, André Z. [Sao Paulo, Inst. Astron. Geofis.; Welch, Brian [Fermilab; Caminha, Gabriel B. [Bologna Observ.; Erben, Thomas [Argelander Inst. Astron.; Moraes, Bruno [University Coll. London; Shan, Huanyuan [Argelander Inst. Astron.

    2017-08-10

    We present the first weak lensing calibration of $\\mu_{\\star}$, a new galaxy cluster mass proxy corresponding to the total stellar mass of red and blue members, in two cluster samples selected from the SDSS Stripe 82 data: 230 redMaPPer clusters at redshift $0.1\\leq z<0.33$ and 136 Voronoi Tessellation (VT) clusters at $0.1 \\leq z < 0.6$. We use the CS82 shear catalog and stack the clusters in $\\mu_{\\star}$ bins to measure a mass-observable power law relation. For redMaPPer clusters we obtain $M_0 = (1.77 \\pm 0.36) \\times 10^{14}h^{-1} M_{\\odot}$, $\\alpha = 1.74 \\pm 0.62$. For VT clusters, we find $M_0 = (4.31 \\pm 0.89) \\times 10^{14}h^{-1} M_{\\odot}$, $\\alpha = 0.59 \\pm 0.54$ and $M_0 = (3.67 \\pm 0.56) \\times 10^{14}h^{-1} M_{\\odot}$, $\\alpha = 0.68 \\pm 0.49$ for a low and a high redshift bin, respectively. Our results are consistent, internally and with the literature, indicating that our method can be applied to any cluster finding algorithm. In particular, we recommend that $\\mu_{\\star}$ be used as the mass proxy for VT clusters. Catalogs including $\\mu_{\\star}$ measurements will enable its use in studies of galaxy evolution in clusters and cluster cosmology.

  12. Preparation of weak-light-driven TiO2-based catalysts via adsorbed-layer nanoreactor synthesis and enhancement of their photo-degradation performance in seawater

    Science.gov (United States)

    Wang, Ting; Xu, Zhi-yong; Zhu, Yi-chen; Wu, Li-guang; Yuan, Hao-xuan; Li, Chang-chun; Liu, Ya-yu; Cai, Jing

    2017-11-01

    Graphene oxide (GO) was first employed as a support in preparing TiO2 nanoparticles by adsorbed-layer nanoreactor synthesis (ALNS). Both TiO2 crystallization and GO reduction simultaneously occurred during solvothermal treatment with alcohol as a solvent. By transmission electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy, the results showed that TiO2 nanoparticles with less than 10 nm of size distributed very homogeneously on the GO surface. Tight interaction between TiO2 particles and GO surface could effectively inhibit the aggregation of TiO2 particles, during solvothermal treatment for anatase TiO2 formation. Alcohol could also reduce oxygenated functional groups on GO surface after solvothermal treatment. TiO2 particles with small size and the decrease in oxygenated functional groups on the GO surface both caused high separation efficiency of photo-generated charge carriers, thus resulting in high photo-degradation performance of catalysts. Strong phenol adsorption on photocatalyst was key to enhancing photo-degradation efficiency for phenol in seawater. Moreover, the change in catalyst structure was minimal at different temperatures of solvothermal treatment. But, the degradation rate and efficiency for phenol in seawater were obviously enhanced because of the sensitive structure-activity relationship of catalysts under weak-light irradiation.

  13. Coumarin-indole conjugate donor-acceptor system: Synthesis, photophysical properties, anion sensing ability, theoretical and biological activity studies of two coumarin-indole based push-pull dyes

    Science.gov (United States)

    Aksungur, Tuğçe; Aydıner, Burcu; Seferoğlu, Nurgül; Özkütük, Müjgan; Arslan, Leyla; Reis, Yasemin; Açık, Leyla; Seferoğlu, Zeynel

    2017-11-01

    Two coumarin-indole conjugate fluorescent dyes having donor-acceptor-donor (D-A-D) (CI-1 and CI-2) were synthesized, and characterized using IR, 1H/13C NMR and HRMS. The absorption and emission properties of the dyes were determined in different solvents. The anion sensitivity and selectivity of the dyes were studied with some anions (CN-, F-, AcO-, Cl-, Br-, I-, HSO4- and H2PO4-) in DMSO, and their interaction mechanisms were evaluated by spectrophotometric and 1H NMR titration techniques. In addition, the molecular and electronic structures of CI-1, as well as the molecular complexes of CI-1, formed with the anions (F- and AcO-), were obtained theoretically and confirmed by DFT and TD-DFT calculations. CI-1 behaves as a colorimetric chemosensor for selective and sensitive detection of CN- in DMSO/H2O (9:1) over other competing anions such as F- and AcO-. However, only CN- interacts with chromophore CI-2 via Michael addition and the main absorption maxima shifts hypsochromically with an observed distinctive color change from orange to yellow. For using as a optic dye, the thermal stability properties of the dyes was determined by TGA (Thermal Gravimetric Analysis). Antimicrobial, antifungal and DNA-ligand interaction studies of the dyes were also examined. The dyes cause conformational changes on DNA and selectively bind to nucleotides of A/A and G/G.

  14. Resisting Weakness of the Will.

    Science.gov (United States)

    Levy, Neil

    2011-01-01

    I develop an account of weakness of the will that is driven by experimental evidence from cognitive and social psychology. I will argue that this account demonstrates that there is no such thing as weakness of the will: no psychological kind corresponds to it. Instead, weakness of the will ought to be understood as depletion of System II resources. Neither the explanatory purposes of psychology nor our practical purposes as agents are well-served by retaining the concept. I therefore suggest that we ought to jettison it, in favour of the vocabulary and concepts of cognitive psychology.

  15. The paradox of hydrogen-bonded anion-anion aggregates in oxoanions: a fundamental electrostatic problem explained in terms of electrophilic···nucleophilic interactions.

    Science.gov (United States)

    Mata, Ignasi; Molins, Elies; Alkorta, Ibon; Espinosa, Enrique

    2015-01-08

    A theoretical study of anionic complexes formed by two partly deprotonated oxoacids joined by hydrogen bonds has been carried out at the MP2 computational level. In spite of the ionic repulsion, local energy minima are found both in the gas phase and in aqueous solution. Electrostatic potential and electron density topologies, and the comparison with neutral complexes formed by oxoacids, reveal that the ionization has no significant effect on the properties of the hydrogen bonds. The stability of the complexes in the gas phase is explained by attractive forces localized in a volume situated in the hydrogen bond and defined as the electrostatic attraction region (EAR) and determined by the topological analyses of the electron density and the electrostatic potential, and by the electric field lines. In solution, the strong anionic repulsion is mostly screened by the effect of the surrounding polar solvent, which only leads to a weak destabilizing interaction in the hydrogen bond region and finally favors the overall stability of the complexes. The anion-anion complexes have been compared with the corresponding neutral ones (as salts or protonated forms), showing that EAR remains unchanged along the series.

  16. Fragmentations of [M-H]- anions of peptides containing Ser sulfate. A joint experimental and theoretical study.

    Science.gov (United States)

    Tran, T T Nha; Wang, Tianfang; Hack, Sandra; Bowie, John H

    2013-11-15

    To determine the negative-ion cleavages from [M-H](-) ions of Ser sulfate-containing peptides using experiment and theory in concert. Fragmentations were explored using a Waters QTOF2 mass spectrometer in negative-ion electrospray mode, together with calculations at the CAM-B3LYP/6-311++g(d,p) level of theory. Peptides used in this study were: GS(SO3H)(OH) 1 GS(SO3H)(OCH3) 1a GAVS(SO3H)(OH) 2 GAVS(SO3H)(OCH3) 2a GLS(SO3H)(GVA(OH) 3 GLS(SO3H)GDA(OH) 4 GLS(SO3H)GS(SO3H)A(OH) 5. Previously, it has been shown that a peptide containing a Tyr sulfate group shows [(M-H)(-) -SO3] as the base peak. Only a small peak was observed corresponding to HOSO3(-) (formed following rearrangement of the sulfate). A Ser sulfate-containing peptide, in contrast, shows pronounced peaks due to cleavage product anions [(M-H)(-)-SO3] and HOSO3(-). Theoretical calculations at the CAM-B3LYP/6-311++g(d,p) level of theory suggest that rearrangement of a Ser sulfate to give C-terminal CO2SO3H is energetically unfavourable in comparison with fragmentation of the intact Ser sulfate to yield [(M-H)(-)-SO3] and HOSO3(-). [(M-H)(-)-H2SO4] anions are not observed in the spectra of peptides containing Ser sulfate, presumably because HOSO3(-) is a relatively weak gas-phase base (ΔGacid = 1265 kJ mol(-1)). Experimental and theoretical data suggest that [(M-H)(-)-SO3] and HOSO3(-) product anions (from a peptide with a C-terminal Ser sulfate) are formed from the serine sulfate anion accompanied by specific proton transfer. CID MS/MS/MS data for an [(M-H)(-)-SO3] ion of an underivatised sulfate-containing peptide will normally allow the determination of the amino acid sequence of that peptide. The one case we have studied where that is not the case is GLS(SO3H)GDA(OH), where the peptide contains Ser sulfate and Asp, where the diagnostic Asp cleavages are competitive with the Ser sulfate cleavages. Copyright © 2013 John Wiley & Sons, Ltd.

  17. Contextuality under weak assumptions

    Science.gov (United States)

    Simmons, Andrew W.; Wallman, Joel J.; Pashayan, Hakop; Bartlett, Stephen D.; Rudolph, Terry

    2017-03-01

    The presence of contextuality in quantum theory was first highlighted by Bell, Kochen and Specker, who discovered that for quantum systems of three or more dimensions, measurements could not be viewed as deterministically revealing pre-existing properties of the system. More precisely, no model can assign deterministic outcomes to the projectors of a quantum measurement in a way that depends only on the projector and not the context (the full set of projectors) in which it appeared, despite the fact that the Born rule probabilities associated with projectors are independent of the context. A more general, operational definition of contextuality introduced by Spekkens, which we will term ‘probabilistic contextuality’, drops the assumption of determinism and allows for operations other than measurements to be considered contextual. Even two-dimensional quantum mechanics can be shown to be contextual under this generalised notion. Probabilistic noncontextuality represents the postulate that elements of an operational theory that cannot be distinguished from each other based on the statistics of arbitrarily many repeated experiments (they give rise to the same operational probabilities) are ontologically identical. In this paper, we introduce a framework that enables us to distinguish between different noncontextuality assumptions in terms of the relationships between the ontological representations of objects in the theory given a certain relation between their operational representations. This framework can be used to motivate and define a ‘possibilistic’ analogue, encapsulating the idea that elements of an operational theory that cannot be unambiguously distinguished operationally can also not be unambiguously distinguished ontologically. We then prove that possibilistic noncontextuality is equivalent to an alternative notion of noncontextuality proposed by Hardy. Finally, we demonstrate that these weaker noncontextuality assumptions are sufficient to prove

  18. Weak Coupling Phases future directions

    CERN Document Server

    Rosner, Jonathan L.

    2003-01-01

    Recent results obtained from B decays on the phases of weak couplings described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix are discussed, with particular emphasis on $\\alpha$ and $\\gamma = \\pi - \\beta - \\alpha$.

  19. D Models for All: Low-Cost Acquisition Through Mobile Devices in Comparison with Image Based Techniques. Potentialities and Weaknesses in Cultural Heritage Domain

    Science.gov (United States)

    Santagati, C.; Lo Turco, M.; Bocconcino, M. M.; Donato, V.; Galizia, M.

    2017-11-01

    Nowadays, 3D digital imaging proposes effective solutions for preserving the expression of human creativity across the centuries, as well as is a great tool to guarantee global dissemination of knowledge and wide access to these invaluable resources of the past. Nevertheless, in several cases, a massive digitalisation of cultural heritage items (from the archaeological site up to the monument and museum collections) could be unworkable due to the still high costs in terms of equipment and human resources: 3D acquisition technologies and the need of skilled team within cultural institutions. Therefore, it is necessary to explore new possibilities offered by growing technologies: the lower costs of these technologies as well as their attractive visual quality constitute a challenge for researchers. Besides these possibilities, it is also important to consider how information is spread through graphic representation of knowledge. The focus of this study is to explore the potentialities and weaknesses of a newly released low cost device in the cultural heritage domain, trying to understand its effective usability in museum collections. The aim of the research is to test their usability, critically analysing the final outcomes of this entry level technology in relation to the other better assessed low cost technologies for 3D scanning, such as Structure from Motion (SfM) techniques (also produced by the same device) combined with dataset generated by a professional digital camera. The final outcomes were compared in terms of quality definition, time processing and file size. The specimens of the collections of the Civic Museum Castello Ursino in Catania have been chosen as the site of experimentation.

  20. 3D MODELS FOR ALL: LOW-COST ACQUISITION THROUGH MOBILE DEVICES IN COMPARISON WITH IMAGE BASED TECHNIQUES. POTENTIALITIES AND WEAKNESSES IN CULTURAL HERITAGE DOMAIN

    Directory of Open Access Journals (Sweden)

    C. Santagati

    2017-11-01

    Full Text Available Nowadays, 3D digital imaging proposes effective solutions for preserving the expression of human creativity across the centuries, as well as is a great tool to guarantee global dissemination of knowledge and wide access to these invaluable resources of the past. Nevertheless, in several cases, a massive digitalisation of cultural heritage items (from the archaeological site up to the monument and museum collections could be unworkable due to the still high costs in terms of equipment and human resources: 3D acquisition technologies and the need of skilled team within cultural institutions. Therefore, it is necessary to explore new possibilities offered by growing technologies: the lower costs of these technologies as well as their attractive visual quality constitute a challenge for researchers. Besides these possibilities, it is also important to consider how information is spread through graphic representation of knowledge. The focus of this study is to explore the potentialities and weaknesses of a newly released low cost device in the cultural heritage domain, trying to understand its effective usability in museum collections. The aim of the research is to test their usability, critically analysing the final outcomes of this entry level technology in relation to the other better assessed low cost technologies for 3D scanning, such as Structure from Motion (SfM techniques (also produced by the same device combined with dataset generated by a professional digital camera. The final outcomes were compared in terms of quality definition, time processing and file size. The specimens of the collections of the Civic Museum Castello Ursino in Catania have been chosen as the site of experimentation.

  1. LC-MS/MS analysis of pramipexole in mouse plasma and tissues: elimination of lipid matrix effects using weak cation exchange mode based solid-phase extraction.

    Science.gov (United States)

    Guo, Weilin; Li, Gao; Yang, Yanxia; Yang, Conglian; Si, Luqin; Huang, Jiangeng

    2015-04-15

    Intranasal delivery is emerging as a promising alternative for oral or intravenous administration of central nervous system (CNS) drugs, such as pramipexole which is widely used for the treatment of Parkinson's disease. To evaluate the effectiveness of intranasal delivery of pramipexole, preclinical pharmacokinetic and tissue distribution studies following intranasal administration need to be investigated. In this paper, we developed and validated a robust and sensitive LC-MS/MS assay without matrix effect for accurate measurements of pramipexole in mouse plasma and tissue samples. Pramipexole and its stable isotope labeled internal standard (d3-pramipexole) were extracted from biological samples by protein precipitation (PPT) coupled with solid phase extraction (SPE) using weak cation exchange SPE cartridges. Matrix effects were studied using post-column infusion and post-extraction addition experiments by direct monitoring of typical phospholipids including glycerophosphocholines (GPChos) and lysoglycerophosphocholines (Lyso-GPChos). Chromatographic separation was achieved on a Welch Ultimate(®) XB-CN column using isocratic elution with a run time of 3.0 min. The assay was linear in the concentration range of 0.05-100 ng/mL and the intra- and inter-day precision and accuracy met the acceptance criteria. Compared with previous reported assays, the current sample preparation approach exhibited significant reduction of matrix effects due to the dramatically decreased levels of residual matrix components such as GPChos and Lyso-GPChos. This method has been successfully applied to pharmacokinetic and tissue distribution studies of pramipexole in mice following a single intravenous or intranasal dose of 50 μg/kg. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Weakly compact operators and interpolation

    OpenAIRE

    Maligranda, Lech

    1992-01-01

    The class of weakly compact operators is, as well as the class of compact operators, a fundamental operator ideal. They were investigated strongly in the last twenty years. In this survey, we have collected and ordered some of this (partly very new) knowledge. We have also included some comments, remarks and examples. The class of weakly compact operators is, as well as the class of compact operators, a fundamental operator ideal. They were investigated strongly in the last twenty years. I...

  3. Weak interactions of elementary particles

    CERN Document Server

    Okun, Lev Borisovich

    1965-01-01

    International Series of Monographs in Natural Philosophy, Volume 5: Weak Interaction of Elementary Particles focuses on the composition, properties, and reactions of elementary particles and high energies. The book first discusses elementary particles. Concerns include isotopic invariance in the Sakata model; conservation of fundamental particles; scheme of isomultiplets in the Sakata model; universal, unitary-symmetric strong interaction; and universal weak interaction. The text also focuses on spinors, amplitudes, and currents. Wave function, calculation of traces, five bilinear covariants,

  4. Acute muscular weakness in children

    Directory of Open Access Journals (Sweden)

    Ricardo Pablo Javier Erazo Torricelli

    Full Text Available ABSTRACT Acute muscle weakness in children is a pediatric emergency. During the diagnostic approach, it is crucial to obtain a detailed case history, including: onset of weakness, history of associated febrile states, ingestion of toxic substances/toxins, immunizations, and family history. Neurological examination must be meticulous as well. In this review, we describe the most common diseases related to acute muscle weakness, grouped into the site of origin (from the upper motor neuron to the motor unit. Early detection of hyperCKemia may lead to a myositis diagnosis, and hypokalemia points to the diagnosis of periodic paralysis. Ophthalmoparesis, ptosis and bulbar signs are suggestive of myasthenia gravis or botulism. Distal weakness and hyporeflexia are clinical features of Guillain-Barré syndrome, the most frequent cause of acute muscle weakness. If all studies are normal, a psychogenic cause should be considered. Finding the etiology of acute muscle weakness is essential to execute treatment in a timely manner, improving the prognosis of affected children.

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

    Science.gov (United States)

    2014-06-24

    AEM is often inconvenient, as ambient carbon dioxide (at publication time, 400 ppm) will react with the OH− to form a mixture of CO3 2− and HCO3 − in...T. In and Ex Situ Characterization of an Anion-Exchange Membrane for Alkaline Direct Methanol Fuel Cell (Admfc). J. Power Sources 2011, 196, 6153...exchange membranes (AEMs) have the potential to enable new electrochemical devices based on catalysis in alkaline media such as fuel cells or electrolyzers.2

  6. Cation modules as building blocks forming supramolecular assemblies with planar receptor-anion complexes.

    Science.gov (United States)

    Dong, Bin; Sakurai, Tsuneaki; Honsho, Yoshihito; Seki, Shu; Maeda, Hiromitsu

    2013-01-30

    Ion-based materials were fabricated through ion pairing of planar receptor-anion complexes and cation modules as negatively and positively charged building blocks, respectively. Anion receptors that could not form soft materials by themselves provided mesophases upon anion binding and subsequent ion pairing with aliphatic cation modules. The mesogenic behaviors were affected by structural modification of both the cation module and the anion receptor. Synchrotron X-ray diffraction measurements suggested the formation of columnar mesophases with contributions from charge-by-charge and charge-segregated arrangements. Flash-photolysis time-resolved microwave conductivity measurements further revealed a higher charge-carrier mobility in the assembly with a large contribution from the charge-segregated arrangement than in the charge-by-charge-based assembly.

  7. Peak shapes of acids and bases under overloaded conditions in reversed-phase liquid chromatography, with weakly buffered mobile phases of various pH: a thermodynamic interpretation.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2009-01-02

    species adsorbs strongly on a first type of sites that have a high density while the ionic species adsorb preferentially on a second type of sites that have a very low density. The evolution of the peak shape when the pHWS changes from acidic to basic is well explained by the weak buffer capacity of the mobile phase used compared to the concentration of the eluted compounds.

  8. Highly Water Resistant Anion Exchange Membrane for Fuel Cells.

    Science.gov (United States)

    Yang, Zhengjin; Hou, Jianqiu; Wang, Xinyu; Wu, Liang; Xu, Tongwen

    2015-07-01

    For anion exchange membranes (AEMs), achieving efficient hydroxide conductivity without excessive hydrophilicity presents a challenge. Hence, new strategies for constructing mechanically strengthened and hydroxide conductive (especially at controlled humidity) membranes are critical for developing better AEMs. Macromolecular modification involving ylide chemistry (Wittig reaction) for the fabrication of novel AEMs with an interpenetrating polymer network structure is reported. The macromolecular modification is cost effective, facile, and based on a one-pot synthesis. AEM water uptake is reduced to 3.6 wt% and a high hydroxide conductivity (69.7 mS cm(-1) , 90 °C) is achieved simultaneously. More importantly, the membrane exhibits similar tensile strength (>35 MPa) and comparable flexibility in both dry and wet states. These AEMs could find further applications within anion exchange membrane fuel cells with low humidity or photoelectric assemblies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Studies of anions sorption on natural zeolites.

    Science.gov (United States)

    Barczyk, K; Mozgawa, W; Król, M

    2014-12-10

    This work presents results of FT-IR spectroscopic studies of anions-chromate, phosphate and arsenate - sorbed from aqueous solutions (different concentrations of anions) on zeolites. The sorption has been conducted on natural zeolites from different structural groups, i.e. chabazite, mordenite, ferrierite and clinoptilolite. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA(+)) and organo-zeolites were obtained. External cation exchange capacities (ECEC) of organo-zeolites were measured. Their values are 17mmol/100g for chabazite, 4mmol/100g for mordenite and ferrierite and 10mmol/100g for clinoptilolite. The used initial inputs of HDTMA correspond to 100% and 200% ECEC of the minerals. Organo-modificated sorbents were subsequently used for immobilization of mentioned anions. It was proven that aforementioned anions' sorption causes changes in IR spectra of the HDTMA-zeolites. These alterations are dependent on the kind of anions that were sorbed. In all cases, variations are due to bands corresponding to the characteristic Si-O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolites). Alkylammonium surfactant vibrations have also been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO4(2-), AsO4(3-) and PO4(3-) ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of anions were determined by spectrophotometric method. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Peak shapes of acids and bases under overloaded conditions in reversed-phase liquid chromatography, with weakly buffered mobile phases of various pH: A thermodynamic interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

    2009-01-01

    excellent agreement was achieved between experimental profiles and those calculated with a two-sites adsorption isotherm model at all {sub W}{sup S}pHs. The neutral species adsorbs strongly on a first type of sites that have a high density while the ionic species adsorb preferentially on a second type of sites that have a very low density. The evolution of the peak shape when the {sub W}{sup S}pH changes from acidic to basic is well explained by the weak buffer capacity of the mobile phase used compared to the concentration of the eluted compounds.

  11. Quantum discord with weak measurements

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Uttam, E-mail: uttamsingh@hri.res.in; Pati, Arun Kumar, E-mail: akpati@hri.res.in

    2014-04-15

    Weak measurements cause small change to quantum states, thereby opening up the possibility of new ways of manipulating and controlling quantum systems. We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the “super quantum discord”, is always larger than the quantum discord captured by the strong measurement. Moreover, we prove the monotonicity of the super quantum discord as a function of the measurement strength and in the limit of strong projective measurement the super quantum discord becomes the normal quantum discord. We find that unlike the normal discord, for pure entangled states, the super quantum discord can exceed the quantum entanglement. Our results provide new insights on the nature of quantum correlation and suggest that the notion of quantum correlation is not only observer dependent but also depends on how weakly one perturbs the composite system. We illustrate the key results for pure as well as mixed entangled states. -- Highlights: •Introduced the role of weak measurements in quantifying quantum correlation. •We have introduced the notion of the super quantum discord (SQD). •For pure entangled state, we show that the SQD exceeds the entanglement entropy. •This shows that quantum correlation depends not only on observer but also on measurement strength.

  12. Performance of polyethylene based radiation grafted anion exchange membrane with polystyrene-b-poly (ethylene/butylene)-b-polystyrene based ionomer using NiCo2O4 catalyst for water electrolysis

    Science.gov (United States)

    Gupta, Gaurav; Scott, Keith; Mamlouk, Mohamed

    2018-01-01

    A soluble anion exchange ionomer with high OH- ion conductivity comparable to that of H+ conductivity of Nafion is synthesised by chloromethylation of polystyrene-b-poly (ethylene/butylene)-b-polystyrene (SEBS) and used with NiCo2O4 electro-catalyst for water electrolysis. The ionomer has an ion exchange capacity of 1.9 mmol g-1 and ionic conductivity of 0.14 S cm-2 at 50 °C. The cell voltage at 20 °C at 100 mA cm-2 is 1.77 and 1.72 V in, 0.1 and 1.0 M NaOH, respectively, for an optimum loading of 10 mg cm-2 NiCo2O4. At 10 mg cm-2 NiCo2O4 electrolyser cell performance is at least equal to or superior to that of IrO2 at 2 mg cm-2 with excellent stability over 1 h. When the catalyst is sprayed on the GDL instead of CCM, the performance is further improved to 1.65 V at 100 mA cm-2 at 60 °C & 0.1 M KOH. The limited AEM electrolyser performance when operating with deionised water in comparison to PEM and alkaline electrolyser arises from the sluggish OER in the AEM environment equivalent to pH of 11.5 and the two orders of magnitude lower HER activity with respect to acid medium combined with the high Tafel slope of 120 mV dec-1.

  13. Anion Recognition by Aliphatic Helical Oligoureas.

    Science.gov (United States)

    Diemer, Vincent; Fischer, Lucile; Kauffmann, Brice; Guichard, Gilles

    2016-10-24

    Anion binding properties of neutral helical foldamers consisting of urea type units in their backbone have been investigated. (1) H NMR titration studies in various organic solvents including DMSO suggest that the interaction between aliphatic oligoureas and anions (CH3 COO(-) , H2 PO4(-) , Cl(-) ) is site-specific, as it largely involves the urea NHs located at the terminal end of the helix (positive pole of the helix), which do not participate to the helical intramolecular hydrogen-bonding network. This mode of binding parallels that found in proteins in which anion-binding sites are frequently found at the N-terminus of an α-helix. (1) H NMR studies suggest that the helix of oligoureas remains largely folded upon anion binding, even in the presence of a large excess of the anion. This study points to potentially useful applications of oligourea helices for the selective recognition of small guest molecules. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Anion exchange in ionic liquid mixtures.

    Science.gov (United States)

    Cha, Seoncheol; Kim, Doseok

    2015-11-28

    Advantage of ionic liquids as designer solvents can be maximized by mixing different ionic liquids (ILs) for a possibility of continuous tunability of material properties. The property of these mixed ILs would be determined by their microscopic conformation between cations and anions. The mixtures of two ILs having 1-butyl-3-methylimidaolium cations and different anions were investigated by IR and NMR spectroscopy, utilizing that the vibrational frequencies of the C-H stretching and bending modes of the most acidic proton in the imidazolium ring of the cation and the NMR chemical shift for the corresponding proton were clearly distinct between the ILs having different anions. The IR absorption spectra of the IL mixtures at different concentrations were well-matched to weighted sums of the two spectra of the pure ILs. In contrast, the two distinct peaks in the NMR spectra of the pure ILs coalesced into a single peak, which shifted continuously following the relative portion of two different ILs in the mixture. IR spectroscopy in the optical frequency range seems to take the instantaneous snapshot of the cation-anion interaction, while NMR spectroscopy in the radio-frequency (∼500 MHz) range samples over a much longer timescale, enough for the cation to interact with different anion species in the mixture.

  15. Incorporation of cationic electron donor of Ni-pyridyltetrathiafulvalene with anionic electron acceptor of polyoxometalate.

    Science.gov (United States)

    Tsunashima, Ryo; Matsumoto, Takumi; Hoshino, Norihisa; Niiho, Wataru; Kimura, Mizuki; Kondo, Kei; Suyama, Yoshihiko; Nishioka, Yukihiro; Kawamata, Jun; Noro, Shin-ichiro; Nakamura, Takayoshi; Akutagawa, Tomoyuki; Ishiguro, Katsuya

    2012-09-07

    A new salt-[Ni(II)(DMSO)(5)(TTFPy)](2)[α-SiW(12)O(40)] (1)-based on polyoxometalates was prepared by coordinating a cationic electron donor of pyridyltetrathiafulvalene (TTFPy) with Ni(II). Although the TTFPy molecule did not form a salt with the anionic α-[SiW(VI)(12)O(40)](4-) because of the weak charge-transfer (CT) interaction, the coordination of Ni with the pyridyl moiety permitted salt formation driven by electrostatic interaction, giving a single crystal of 1. Crystallographic analysis, UV-vis and IR spectroscopy and electrochemical characterization revealed that the fully oxidized α-[SiW(VI)(12)O(40)](4-) was crystallized with the neutral TTFPy moiety from the acetonitrile solution because of the low electron-withdrawing ability of α-[SiW(VI)(12)O(40)](4-), forming a brown-orange crystal. The crystal colour quickly turned to black by immersing in methanol, due to CT from TTF moiety to α-[SiW(VI)(12)O(40)](4-), which was caused by the solvent effect. Increase in the solvent acceptor number from 18.9 for acetonitrile to 41.3 for methanol resulted in the enhancement of the electron withdrawing ability of α-[SiW(VI)(12)O(40)](4-) by 0.317 V in methanol.

  16. Warping the Weak Gravity Conjecture

    Directory of Open Access Journals (Sweden)

    Karta Kooner

    2016-08-01

    Full Text Available The Weak Gravity Conjecture, if valid, rules out simple models of Natural Inflation by restricting their axion decay constant to be sub-Planckian. We revisit stringy attempts to realise Natural Inflation, with a single open string axionic inflaton from a probe D-brane in a warped throat. We show that warped geometries can allow the requisite super-Planckian axion decay constant to be achieved, within the supergravity approximation and consistently with the Weak Gravity Conjecture. Preliminary estimates of the brane backreaction suggest that the probe approximation may be under control. However, there is a tension between large axion decay constant and high string scale, where the requisite high string scale is difficult to achieve in all attempts to realise large field inflation using perturbative string theory. We comment on the Generalized Weak Gravity Conjecture in the light of our results.

  17. New bifunctional anion-exchange resins for nuclear waste treatment: Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, S.F.; Jarvinen, G.D.; Barr, M.E. [Los Alamos National Lab., NM (United States); Bartsch, R.A. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Chemistry and Biochemistry

    1997-06-01

    Additional bifunctional anion-exchange resins have been designed, synthesized and evaluated for their ability to take up Pu(IV) from nitric acid solutions. Bifunctionality is achieved by adding a second anion-exchange site to the pyridine nitrogen (also an anion-exchange site) of the base poly(4-vinylpyridine) resin. Previous work focused on the effect of varying the chemical properties of the added site along with the length of an alkylene spacer between the two sites. Here the authors examine four new 3- and 4-picolyl derivatives which maintain more rigidly defined geometries between the two nitrogen cationic sites. These materials, which have the two anion-exchange sites separated by three and four carbons, respectively, exhibit lower overall Pu(IV) distribution coefficients than the corresponding N-alkylenepyridium derivatives with more flexible spacers. Methylation of the second pyridium site results in a ca. 20% increase in the Pu(IV) distribution coefficients.

  18. Cosmology and the weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N. (Fermi National Accelerator Lab., Batavia, IL (USA)):(Chicago Univ., IL (USA))

    1989-12-01

    The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

  19. Nonlinear waves and weak turbulence

    CERN Document Server

    Zakharov, V E

    1997-01-01

    This book is a collection of papers on dynamical and statistical theory of nonlinear wave propagation in dispersive conservative media. Emphasis is on waves on the surface of an ideal fluid and on Rossby waves in the atmosphere. Although the book deals mainly with weakly nonlinear waves, it is more than simply a description of standard perturbation techniques. The goal is to show that the theory of weakly interacting waves is naturally related to such areas of mathematics as Diophantine equations, differential geometry of waves, Poincaré normal forms, and the inverse scattering method.

  20. Fusing N-heterocyclic carbenes with carborane anions.

    Science.gov (United States)

    El-Hellani, Ahmad; Lavallo, Vincent

    2014-04-22

    Here we describe the fusion of two families of unusual carbon-containing molecules that readily disregard the tendency of carbon to form four chemical bonds, namely N-heterocyclic carbenes (NHCs) and carborane anions. Deprotonation of an anionic imidazolium salt with lithium diisopropylamide at room temperature leads to a mixture of lithium complexes of C-2 and C-5 dianionic NHC constitutional isomers as well as a trianionic (C-2, C-5) adduct. Judicious choice of the base and reaction conditions allows the selective formation of all three stable polyanionic carbenes. In solution, the so-called abnormal C-5 NHC lithium complex slowly isomerizes to the normal C-2 NHC, and the process can be proton-catalyzed by the addition of the anionic imidazolium salt. These results indicate that the combination of two unusual forms of carbon atoms can lead to unexpected chemical behavior, and that this strategy paves the way for the development of a broad new generation of NHC ligands for catalysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.