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Sample records for cetyl pyridinium bromide

  1. Release of cetyl pyridinium chloride from fatty acid chelate temporary dental cement

    PubMed Central

    Hurt, Andrew; Coleman, Nichola J.; Tüzüner, Tamer; Bagis, Bora; Korkmaz, Fatih Mehmet; Nicholson, John W.

    2016-01-01

    Abstract Objective To determine whether the antimicrobial nature of a fatty acid chelate temporary dental cement can be enhanced by the addition of 5% cetyl pyridinium chloride (CPC). Materials and methods The temporary cement, Cavex Temporary was employed, and additions of CPC were made to either the base or the catalyst paste prior to mixing the cement. Release of CPC from set cement specimens was followed using reverse-phase HPLC for a period of up to 2 weeks following specimen preparation. Potential interactions between Cavex and CPC were examined by Fourier transform infrared spectroscopy (FTIR) and antimicrobial effects were determined using zone of inhibition measurements after 24 h with disc-shaped specimens in cultured Streptococcus mutans. Results FTIR showed no interaction between CPC and the components of the cement. CPC release was found to follow a diffusion mechanism for the first 6 h or so, and to equilibrate after approximately 2 weeks, with no significant differences between release profiles when the additive was incorporated into the base or the catalyst paste. Diffusion was rapid, and had a diffusion coefficient of approximately 1 × 10−9 m2 s−1 in both cases. Total release was in the range 10–12% of the CPC loading. Zones of inhibition around discs containing CPC were significantly larger than those around the control discs of CPC-free cement. Conclusions The antimicrobial character of this temporary cement can be enhanced by the addition of CPC. Such enhancement is of potential clinical value, though further in vivo work is needed to confirm this. PMID:27335898

  2. The sensitivity to chlorhexidine and cetyl pyridinium chloride of staphylococci on the hands of dental students and theatre staff exposed to these disinfectants.

    PubMed

    Millns, B; Martin, M V; Field, E A

    1994-02-01

    The aim of this investigation was to study the possible emergence of resistant isolates of the genus Staphylococcus on the hands of dental personnel who use 'Hibiscrub' (chlorhexidine-detergent preparation) and cetyl pyridinium-coated gloves. Resistance was determined by a rate-of-kill technique. In four dental student groups (first, second, third and fourth years) no microorganisms survived 30 min exposure to cetyl pyridinium chloride (CPC) or to chlorhexidine diacetate (CDA). In a theatre staff group, no microorganisms survived 30 s exposure to CPC; and only one of 23 isolates survived 30 min exposure to CDA, but was killed after 60 min exposure. It is concluded that staphylococci resistant to either of these disinfectants do not present a problem in dental students or theatre staff. PMID:7911154

  3. Investigation of pyridine/propargyl bromide reaction and strong fluorescence enhancements of the resultant poly(propargyl pyridinium bromide).

    PubMed

    Zhou, Changming; Gao, Yong; Chen, Daoyong

    2012-09-20

    Poly(propargyl pyridinium bromide), a kind of conjugated polyelectrolyte with polyacetylene as the backbone and pyridinium as side groups, was synthesized simply via reaction between pyridine and propargyl bromide under mild conditions. The resultant polymer was characterized by (1)H NMR, elemental analysis, FT-IR, and GPC-MALLS. An alkyne group was confirmed as the end group of the polymer chains by the alkyne/azide click chemistry, which reveals that the polymerization is terminated by the reaction between propargyl bromide and carbon anions. It is known that monosubstituted polyacetylenes reported have very weak fluorescence intensities, which limit their applications. As a monosubstituted polyacetylene, the freshly prepared poly(propargyl pyridinium bromide) also has a very weak fluorescence. However, we confirmed that addition of some anions to the polymer solution in DMF or DMSO leads to the fluorescence enhancements up to 25 times. Besides, heating the polymer solution at a temperature between 70 and 130 °C for longer than 0.5 h greatly enhanced the fluorescence intensity. The interaction with the anions or the heating enhances the effective exciton confinement within the conjugated backbone and thus results in the fluorescence enhancements. After the fluorescence enhancements, poly(propargyl pyridinium bromide) has relatively strong fluorescence emissions, which will make it promising in fluorescence-based applications. PMID:22928912

  4. Investigating Two-Photon-Induced Fluorescence in Rhodamine-6G in Presence of Cetyl-Trimethyl-Ammonium-Bromide.

    PubMed

    Maurya, Sandeep Kumar; Yadav, Dheerendra; Goswami, Debabrata

    2016-09-01

    We investigate the effect of cetyl-trimethyl-ammonium-bromides (CTAB) concentration on the fluorescence of Rhodamine-6G in water. This spectroscopic study of Rhodamine-6G in presence of CTAB was performed using two-photon-induced-fluorescence at 780 nm wavelength using high repetition rate femtosecond laser pulses. We report an increment of ∼10 % in the fluorescence in accordance with ∼12 % enhancement in the absorption intensity of the dye molecule around the critical micellar concentration. We discuss the possible mechanism for the enhancement in the two-photon fluorescence intensity and the importance of critical micellar concentration. PMID:27324955

  5. Crystal structure of 3-amino-1-propyl­pyridinium bromide

    PubMed Central

    Venkatesan, P.; Rajakannan, V.; Thamotharan, S.

    2014-01-01

    The title mol­ecular salt, C8H13N2 +·Br−, crystallizes with two independent 3-amino­pyridinium cations and two bromide anions in the asymmetric unit (Z′ = 2). In the pyridine ring, the N atom is alkyl­ated by a propyl group. The dihedral angle between the mean planes of the pyridinium ring and the propyl group is 84.84 (2)° in cation A, whereas the corresponding angle is 89.23 (2)° in cation B. In the crystal, the anions and cations are linked via N—H⋯Br and C—H⋯Br hydrogen bonds, forming chains propagating along [100]. PMID:25552997

  6. Enhanced adsorption of congo red from aqueous solutions by chitosan hydrogel beads impregnated with cetyl trimethyl ammonium bromide.

    PubMed

    Chatterjee, Sudipta; Lee, Dae S; Lee, Min W; Woo, Seung H

    2009-06-01

    The adsorption of congo red (CR) onto chitosan (CS) beads impregnated by a cationic surfactant (CTAB, cetyl trimethyl ammonium bromide) was investigated. Chitosan beads impregnated at a ratio of 1/20 of CTAB to CS (0.05% of CTAB and 1% of CS) increased the CR adsorption capacity by 2.2 times from 162.3 mg/g (0% CTAB) to 352.5 mg/g (0.05% CTAB). The CR adsorption decreased with an increase in pH of the CR solution from 4.0 to 9.0. The Sips isotherm model showed a good fit with the equilibrium experimental data and the values of the heterogeneity factor (n) indicated heterogeneous adsorption of CR onto CS/CTAB beads, as well as CS beads. The kinetic data showed better fit to the pseudo second-order rate model than to the pseudo first-order rate model. The impregnation of CS beads by cationic surfactants showed the highest adsorption capacities of CR compared to any other adsorbents and would be a good method to increase adsorption efficiency for the removal of anionic dyes in a wastewater treatment process. PMID:19208471

  7. Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

    NASA Astrophysics Data System (ADS)

    Hlaing, Nwe Ni; Vignesh, K.; Sreekantan, Srimala; Pung, Swee-Yong; Hinode, Hirofumi; Kurniawan, Winarto; Othman, Radzali; Thant, Aye Aye; Mohamed, Abdul Rahman; Salim, Chris

    2016-02-01

    Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2-0.8 M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG-DTA) techniques. The phase purity, crystallite size, Brunauer-Emmett-Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8 M. TGA results exhibited that 0.8 M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

  8. Thermochemistry of alkyl pyridinium bromide ionic liquids: calorimetric measurements and calculations.

    PubMed

    Tong, Bo; Liu, Qing-Shan; Tan, Zhi-Cheng; Welz-Biermann, Urs

    2010-03-25

    Two ionic liquids, 1-ethylpyridinium bromide (EPBr) and 1-propylpyridinium bromide (PPBr), were prepared and the structures were characterized by 1H NMR. The thermodynamic properties of EPBr and PPBr were studied with adiabatic calorimetry (AC) and thermogravimatric analysis (TG-DTG). The heat capacity was precisely measured in the temperature range from 78 to 410 K by means of a fully automated adiabatic calorimeter. For EPBr, the melting temperature, enthalpy, and entropy of solid-liquid phase transition were determined to be 391.31 +/- 0.28 K, 12.77 +/- 0.09 kJ x mol(-1), and 32.63 +/- 0.22 J x K(-1) x mol(-1), respectively, and for PPBr they were 342.83 +/- 0.69 K, 10.97 +/- 0.05 kJ x mol(-1), and 32.00 +/- 0.10 J x K(-1) x mol(-1), respectively. The thermodynamic functions (H(T)(0) - H(298.15)(0)) and (S(T)(0) - S(298.15)(0)) were derived from the heat capacity data in the experimental temperature range with an interval of 5 K. The thermostablility of the compounds was further studied by TGA measurements. The phase change behavior and thermodynamic properties were compared and estimated in a series of alkyl pyridinium bromide ionic liquids. Results indicate that EPBr has higher melting and decomposition temperature, as well as phase transition enthalpy and entropy but lower heat capacity than PPBr due to their different molecular structures. PMID:20235601

  9. The Comparative Evaluation of Antibacterial Activity of Methacryloxydodecyl Pyridinium Bromide and Non-methacryloxydodecyl Pyridinium Bromide Dentin Bonding Systems Using Two Different Techniques: An In vitro Study

    PubMed Central

    Deshpande, Prashanth; Nainan, Mohan Thomas; Metta, Kiran Kumar; Shivanna, Vasundhara; Ravi, Ramkrishna; Prashanth, B R

    2014-01-01

    zones (P > 0.05), but the bonding resin of CPB did not produce any inhibition. When tested by the tooth cavity model technique, the application of CPB resulted in significantly less bacterial recovery than the PBNT (P < 0.05), demonstrating substantial antibacterial effects. Conclusion: The CPB that employs the antibacterial primer containing methacryloxydodecyl pyridinium bromide, was effective in inactivating the bacteria in the cavity compared to little antibacterial activity shown by PBNT. The tooth cavity mode test used in the present study is a reliable method to evaluate the antibacterial effects of dentin bonding agents simulating clinical situations. PMID:25395795

  10. Synergistic inhibition behavior between indigo carmine and cetyl trimethyl ammonium bromide on carbon steel corroded in a 0.5 M HCl solution

    NASA Astrophysics Data System (ADS)

    Zhang, Zhe; Tian, Ningchen; Li, Xiuying; Zhang, Lingzhi; Wu, Ling; Huang, Yan

    2015-12-01

    This work reports on a newly observed synergistic inhibition between indigo carmine and cetyl trimethyl ammonium bromide (CTAB) on 1045 carbon steel (CS) corroded in a 0.5 M HCl solution. The results of electrochemical measurements showed that CTAB could change indigo carmine in a manner that would accelerate corrosion and produce an effective inhibitor. The maximal protection efficiency was significantly greater than 0.985, with the concentration of the combination inhibitors reaching approximately 5 × 10-5 M. The microstructure of the CS corrosion surface demonstrated that the indigo disulfonate anions and cetyltrimethylammonium cations were adsorbed simultaneously on the CS surface to protect it from corrosion. Diffusion coefficient analysis and the surface concentration profiles of the corrosive species were used to investigate the synergistic effect of the indigo carmine/CTAB combination inhibitors, and the results demonstrate the existence of synergy.

  11. Complete dechlorination of 2,4-dichlorophenol in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel composite electrode.

    PubMed

    Sun, Zhirong; Wei, Xuefeng; Han, Yanbo; Tong, Shan; Hu, Xiang

    2013-01-15

    The electrochemically reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel electrode (Pd/PPy-CTAB/foam-Ni electrode) was investigated in this paper. Pd/PPy-CTAB/foam-Ni electrode was prepared and characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) adsorption and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The influences of some experimental factors such as the dechlorination current, dechlorination time and the initial pH on the removal efficiency and the current efficiency of 2,4-DCP dechlorination on Pd/PPy-CTAB/foam-Ni electrode were studied. Complete removal of 2,4-DCP was achieved and the current efficiency of 47.4% could be obtained under the conditions of the initial pH of 2.2, the dechlorination current of 5 mA and the dechlorination time of 50 min when the initial 2,4-DCP concentration was 100 mg L(-1). The analysis of high performance liquid chromatography (HPLC) identified that the intermediate products were 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP). The final products were mainly phenol. Its further reduction product cyclohexanone was also detected. The electrocatalytic dechlorination pathways of 2,4-DCP on Pd/PPy-CTAB/foam-Ni electrode were discussed. The stability of the electrode was favorable that it could keep dechlorination efficiency at 100% after having been reused 10 times. Results revealed that the stable prepared Pd/PPy-CTAB/foam-Ni electrode presented a good application prospect in dechlorination process with high effectiveness and low cost. PMID:23270952

  12. Synthesis, antibacterial and antioxidant activities of new 1-alkyl-4-(1-alkyl-4-oxo-1,4-dihydroquinolin-2-yl)pyridinium bromides.

    PubMed

    Kahriman, Nuran; Yaylı, Büşra; Aktaş, Ayça; Iskefiyeli, Zeynep; Beriş, Fatih Şaban; Yaylı, Nurettin

    2013-11-01

    New 1-alkyl-4-(1-alkyl-4-oxo-1,4-dihydroquinolin-2-yl)pyridinium bromides (3a-k) were synthesized from 1,4'-diazaflavone [2-pyridin-4-ylquinolin-4(1H)-one] and evaluated for antibacterial and antioxidant activities. A rapid one-pot preparation of 1,4'-diazaflavone (2) was done from 2'-amino substituted chalcone (1) by intramolecular Michael addition using solvent-free microwave heating. New N,N'-dialkyl substituted (C₅-C₁₅) 1,4'-diazaflavonium bromides were synthesized from compound 2 with corresponding alkyl halides. Compounds 3a-k were active against six bacteria (MIC: 7.8-500.0 μg/mL). They also showed good antioxidant activities in DPPH scavenging (SC₅₀: 45-133 μg/mL) and ferric reducing/antioxidant power (14-141 μM TEAC) tests. The biological activities decreased as alkyl chain length increased. The reason behind the obvious negative effect of alkyl chain elongation is unclear and requires investigations about the intermolecular interactions of these pyridinium salts with bioassay components. PMID:24077525

  13. Spectra, stability and labeling of 1-(5-carboxypentyl)-4-(2-(N-ethyl-carbazole-3-yl) vinyl) pyridinium bromide with a large Stokes shift.

    PubMed

    Gu, Yingchun; Lin, Dayong; Li, Ran; Tang, Yalin; Fei, Xuening; Zhou, Jianguo

    2016-03-01

    Carbazole and its derivatives have been widely utilized as a functional building block in the fabrication of the organic medicine, pesticides, materials, etc., because of their excellent solubility, stability and biological activity. In this paper, 1-(5-carboxypentyl)-4-(2-(N-ethyl-carbazole-3-yl) vinyl) pyridinium bromide with a large Stokes shift was synthesized and characterized by (1) H NMR and MS. The UV/vis absorption and fluorescence spectra in different solvents and at different pH values were investigated preliminarily. The photostability and thermostability were also studied and the results showed that the compound was stable. The compound was also used to label bovine serum albumin (BSA) and calf thymus (ct)DNA. The results showed that the fluorescence intensity is enhanced when labeling with BSA and the binding ability is stronger than ctDNA, making it may be used as a biological probe. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26249113

  14. The reaction of substituted N-phenacyl-pyridinium bromides in the pyridine ring with DABCO and DBU in water and DMSO. Kinetics and DFT studies

    NASA Astrophysics Data System (ADS)

    Szwajca, A.; Łęska, B.; Schroeder, G.; Szafran, M.

    2004-12-01

    The rate constants have been measured for deprotonation reaction of substituted N-phenacyl-pyridinium bromides, in the pyridine ring, with 1,4-diazabicyclo[2,2,2]octane in water and DMSO, and some with 1,8-diazabicyclo[5,4,0]undec-7-ene. The dependence of the rate constant, k, on p Ka of substituted pyridines is made of two distinct linear branches obtained for the salts with electron-withdrawing and electron-donating substituents, respectively. The structures of four salts have been determined by the B3LYP/6-31G(d,p) level of theory and compared with the available X-ray structure. The effect of the substituent and solvent on k values has been discussed.

  15. A novel dodine-free selective medium based on the use of cetyl trimethyl ammonium bromide (CTAB) to isolate Beauveria bassiana, Metarhizium anisopliae sensu lato and Paecilomyces lilacinus from soil.

    PubMed

    Posadas, Julieta B; Comerio, Ricardo M; Mini, Jorge I; Nussenbaum, Ana L; Lecuona, Roberto E

    2012-01-01

    This study evaluated the quaternary ammonium compound cetyl trimethyl ammonium bromide (CTAB) as an alternative to the chemically related dodecylguanidine (dodine) for the selective isolation of entomopathogenic fungi. Oatmeal agar (OA) with chloramphenicol was used as basal medium, and three concentrations of CTAB (0.5, 0.6, 0.7 g/L) were evaluated and compared against OA + 0.46 g/L dodine. Selective isolation and growth studies were performed with the entomopathogens Beauveria bassiana, Metarhizium anisopliae s.l. and Paecilomyces lilacinus and five common non-entomopathogenic non-target species. The three entomopathogenic fungi sporulated earlier on OA + 0.6 g/L CTAB than on OA + 0.46 g/L dodine, while none of the non-target fungi sporulated on OA + 0.6 g/L CTAB. All entomopathogenic fungal isolates grew on OA + 0.6 g/L CTAB, despite some intra-species variation, whereas non-target fungi showed no growth or sporulation. OA + 0.6 g/L CTAB resulted in an efficient medium to isolate B. bassiana, M. anisopliae s. l. and P. lilacinus from soil samples. Results of our study suggest that OA + 0.6 g/L CTAB is a suitable, simple and inexpensive to prepare medium to replace OA + 0.46 g/L dodine for the selective isolation of these fungi. PMID:22314588

  16. Crystal structure of 2,6-bis-(2-hy-droxy-5-methyl-phen-yl)-4-phenyl-pyridinium bromide di-chloro-methane hemisolvate hemihydrate.

    PubMed

    Mankaev, Badma N; Zaitsev, Kirill V; Karlov, Sergey S; Egorov, Mikhail P; Churakov, Andrei V

    2015-12-01

    The asymmetric unit in the structure of the title compound, C25H22NO2 (+)·Br (-)·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di-chloro-methane molecule and a water mol-ecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings being 3.0 (2), 36.4 (1) and 24.2 (1)°, and 3.7 (2), 36.5 (1) and 24.8 (1)°, respectively. In the crystal, the cations, anions and water mol-ecules are linked through O-H⋯O and O-H⋯Br hydrogen bonds, forming an insular unit. Within the cations there are also intra-molecular N-H⋯O hydrogen bonds. Adjacent centrosymmetrically related aggregates are linked by π-π stacking inter-actions between the pyridine ring and a benzene ring in both cations [ring-centroid separations = 3.525 (3) and 3.668 (3) Å], forming chains extending across the ac diagonal. Voids between these chains are filled by dichloromethane molecules. PMID:26870547

  17. Effect of counterion on the mesomorphic behavior and optical properties of columnar pyridinium ionic liquid crystals derived from 4-hydroxypyridine

    NASA Astrophysics Data System (ADS)

    Pană, Amalia; Badea, Florentina L.; Iliş, Monica; Staicu, Teodora; Micutz, Marin; Pasuk, Iuliana; Cîrcu, Viorel

    2015-03-01

    A series of 3,4,5-tridodecyloxybenzyl pyridinium salts derived from 4-hydroxypyridine has been designed and prepared. The liquid crystalline properties of these compounds were investigated by polarized optical microscopy, differential scanning calorimetry and powder X-ray diffraction while their thermal stability was studied by thermogravimetric analysis. The N-3,4,5-tridodecyloxybenzyl-4-pyridone intermediate shows a monotropic columnar hexagonal mesophase ranging from 56 °C down to room temperature while the corresponding bromide dodecyl O-alkylated pyridinium salt shows one enantiotropic columnar mesophase and one additional monotropic columnar phase at lower temperatures. Replacing bromide ion (Br-) with other counterions (NO3-, BF4- and PF6-) resulted in mesophase suppression. These luminescent pyridinium salts show weak emission in dichloromethane solutions at room temperature and a pronounced red-shifted emission in solid state. Photoluminescent properties of the pyridinium salts do not depend significantly on the nature of counterion employed.

  18. Crystal structure of 2,6-bis­(2-hy­droxy-5-methyl­phen­yl)-4-phenyl­pyridinium bromide di­chloro­methane hemisolvate hemihydrate

    PubMed Central

    Mankaev, Badma N.; Zaitsev, Kirill V.; Karlov, Sergey S.; Egorov, Mikhail P.; Churakov, Andrei V.

    2015-01-01

    The asymmetric unit in the structure of the title compound, C25H22NO2 +·Br −·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di­chloro­methane molecule and a water mol­ecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings being 3.0 (2), 36.4 (1) and 24.2 (1)°, and 3.7 (2), 36.5 (1) and 24.8 (1)°, respectively. In the crystal, the cations, anions and water mol­ecules are linked through O—H⋯O and O—H⋯Br hydrogen bonds, forming an insular unit. Within the cations there are also intra­molecular N—H⋯O hydrogen bonds. Adjacent centrosymmetrically related aggregates are linked by π–π stacking inter­actions between the pyridine ring and a benzene ring in both cations [ring-centroid separations = 3.525 (3) and 3.668 (3) Å], forming chains extending across the ac diagonal. Voids between these chains are filled by dichloromethane molecules. PMID:26870547

  19. Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

    PubMed

    Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

    2011-09-01

    Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

  20. Cyanogen bromide

    Integrated Risk Information System (IRIS)

    Cyanogen bromide ; CASRN 506 - 68 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  1. Vinyl bromide

    Integrated Risk Information System (IRIS)

    Vinyl bromide ; CASRN 593 - 60 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  2. Solvent-free enzymatic production of high quality cetyl esters.

    PubMed

    Serrano-Arnaldos, Mar; Máximo-Martín, María Fuensanta; Montiel-Morte, María Claudia; Ortega-Requena, Salvadora; Gómez-Gómez, Elisa; Bastida-Rodríguez, Josefa

    2016-04-01

    A solvent-free biocatalytic process for the synthesis of high quality cetyl laurate, myristate, palmitate and stearate has been optimized. This enzymatic procedure follows the fundamental principles of the Green Chemistry and lead to sustainable products, which can be labeled as natural and conform to the principal requirements for its use in high value-added goods. The four esters selected are the main components of spermaceti, a mixture of waxes very appreciated in cosmetic and pharmacy because of its physical properties and emolliency, which was formerly extracted from the head of the sperm whales. In this paper, the influence of the amount of biocatalyst, the commercially available Novozym(®) 435, and the temperature were studied in an open-air batch reactor before carrying out the synthesis in a high performance vacuum reactor with dry nitrogen input to shift the equilibrium towards product formation. Under optimal conditions, conversion was higher than 98.5 %. The characterization of the enzymatic cetyl esters puts in evidence that these are ultra-pure compounds, which have similar properties to the ones obtained through the conventional industrial processes with the extra benefit of being environmentally friendly. PMID:26801670

  3. Factors influencing the formation of polybromide monoanions in solutions of ionic liquid bromide salts.

    PubMed

    Easton, Max E; Ward, Antony J; Chan, Bun; Radom, Leo; Masters, Anthony F; Maschmeyer, Thomas

    2016-03-01

    Six different bromide salts - tetraethylammonium bromide ([N2,2,2,2]Br, Br), 1-ethyl-1-methylpiperidinium bromide ([C2MPip]Br, Br), 1-ethyl-1-methylpyrrolidinium bromide ([C2MPyrr]Br, Br), 1-ethyl-3-methylimidazolium bromide ([C2MIm]Br, Br), 1-ethylpyridinium bromide ([C2Py]Br, Br), and 1-(2-hydroxyethyl)pyridinium bromide ([C2OHPy]Br, Br) - were studied in regards to their capacity to form polybromide monoanion products on addition of molecular bromine in acetonitrile solutions. Using complementary spectroscopic and computational methods for the examination of tribromide and pentabromide anion formation, key factors influencing polybromide sequestration were identified. Here, we present criteria for the targeted synthesis of highly efficient bromine sequestration agents. PMID:26890026

  4. Supramolecular helical nanofibers assembled from a pyridinium-functionalized methyl glycyrrhetate amphiphile

    NASA Astrophysics Data System (ADS)

    Gao, Yuxia; Hao, Jie; Wu, Jindan; Zhang, Xun; Hu, Jun; Ju, Yong

    2015-08-01

    A glycyrrhetate-containing amphiphile, MGP (1-[2-(methyl glycyrrhetate)-2-oxoethyl]pyridinium bromide), has been synthesized, and found to assemble into supramolecular helical nanofibers in chloroform/aromatic solvents, which are primarily driven by π-π stacking, van der Waals forces, and hydrophobic interactions. During the assembly process, MGP stacked into J-aggregates resulting in the sequestration of the hydrophilic pyridinium cation within the interior with the concomitant projection of its hydrophobic skeleton on the outside surface. Ultimately, this protrusion generated a staggered angle due to the steric hindrance between stacked molecules. This staggered angle further led to molecular misalignments and the formation of helical fibrils, which could twist with each other to fabricate larger helical fibers. Consequently, a gel was formed by intertwining these nanofibers into three-dimensional networks. Using this strategy, we found that other triterpenoid-tailored pyridinium amphiphiles are also potential scaffolds for supramolecular helical structures. This work provides a facile approach for the fabrication of supramolecular macroscopic chiral nanostructures that originate from natural products.A glycyrrhetate-containing amphiphile, MGP (1-[2-(methyl glycyrrhetate)-2-oxoethyl]pyridinium bromide), has been synthesized, and found to assemble into supramolecular helical nanofibers in chloroform/aromatic solvents, which are primarily driven by π-π stacking, van der Waals forces, and hydrophobic interactions. During the assembly process, MGP stacked into J-aggregates resulting in the sequestration of the hydrophilic pyridinium cation within the interior with the concomitant projection of its hydrophobic skeleton on the outside surface. Ultimately, this protrusion generated a staggered angle due to the steric hindrance between stacked molecules. This staggered angle further led to molecular misalignments and the formation of helical fibrils, which could

  5. Application of pyridinium salts derived of barbituric acid in Kröhnke's reaction.

    PubMed

    Prelicz, D; Kasperek, L

    1975-01-01

    A series of pyridinium salts derived of barbituric acid (BAC) was obtained, as starting substances in Kröhnke's reaction. On the example of 3-(1',3'-dimethyl-5'-isopropylbarbituryl-5')-1-acetonylene-N-pyrifinium bromide it was stated that the corresponding nitron can be formed only when in positions 1 and 3 of barbituric ring are no hydrogen atoms able to enolization. 3-(1',3'-Dimethyl-5'-isopropylbarbituryl-5')-pyruvic aldehyde (XIII) was obtained by decomposition of nitron XII. PMID:1144211

  6. Asymmetric Hydrogenation of 3-Substituted Pyridinium Salts.

    PubMed

    Renom-Carrasco, Marc; Gajewski, Piotr; Pignataro, Luca; de Vries, Johannes G; Piarulli, Umberto; Gennari, Cesare; Lefort, Laurent

    2016-07-01

    The use of an equivalent amount of an organic base leads to high enantiomeric excess in the asymmetric hydrogenation of N-benzylated 3-substituted pyridinium salts into the corresponding piperidines. Indeed, in the presence of Et3 N, a Rh-JosiPhos catalyst reduced a range of pyridinium salts with ee values up to 90 %. The role of the base was elucidated with a mechanistic study involving the isolation of the various reaction intermediates and isotopic labeling experiments. Additionally, this study provided some evidence for an enantiodetermining step involving a dihydropyridine intermediate. PMID:27140832

  7. Synthesis, Biological Evaluation and Molecular Docking Study of Hydrazone-Containing Pyridinium Salts as Cholinesterase Inhibitors.

    PubMed

    Parlar, Sulunay; Bayraktar, Gulsah; Tarikogullari, Ayse Hande; Alptüzün, Vildan; Erciyas, Ercin

    2016-01-01

    A series of pyridinium salts bearing alkylphenyl groups at 1 position and hydrazone structure at 4 position of the pyridinium ring were synthesized and evaluated for the inhibition of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. The cholinesterase (ChE) inhibitory activity studies were carried out by using the Ellman's colorimetric method. All compounds displayed considerable AChE and BuChE inhibitory activity and some of the compounds manifested remarkable anti-AChE activity compared to the reference compound, galantamine. Among the title compounds, the series including benzofuran aromatic ring exhibited the best inhibitory activity both on AChE and BuChE enzymes. Compound 3b, 4-[2-(1-(benzofuran-2-yl)ethylidene)hydrazinyl]-1-(3-phenylpropyl)pyridinium bromide, was the most active compound with IC50 value of 0.23 (0.24) µM against enantiomeric excess (ee)AChE (human (h)AChE) while compound 3a, 4-[2-(1-(benzofuran-2-yl)ethylidene)hydrazinyl]-1-phenethylpyridinium bromide, was the most active compound with IC50 value of 0.95 µM against BuChE. Moreover, 3a and b exhibited higher activity than the reference compound galantamine (eeAChE (hAChE) IC50 0.43 (0.52) µM; BuChE IC50 14.92 µM). Molecular docking studies were carried out on 3b having highest inhibitory activity against AChE. PMID:27581632

  8. Methyl Bromide Poisoning

    PubMed Central

    Rathus, E. M.; Landy, P. J.

    1961-01-01

    Seven cases of methyl bromide poisoning which occurred amongst workers engaged on a fumigation project are described. The methods adopted for investigation of the environmental situation are discussed and the measurement of blood bromide levels on random samples of workers is suggested as an index of the effectiveness of equipment and working methods. PMID:13739738

  9. Surfaces of Fluorinated Pyridinium Block Copolymers with Enhanced Antibacterial Activity

    SciTech Connect

    Krishnan,S.; Ward, R.; Hexemer, A.; Sohn, K.; Lee, K.; Angert, E.; Fischer, D.; Kramer, E.; Ober, C.

    2006-01-01

    Polystyrene-b-poly(4-vinylpyridine) copolymers were quaternized with 1-bromohexane and 6-perfluorooctyl-1-bromohexane. Surfaces prepared from these polymers were characterized by contact angle measurements, near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy. The fluorinated pyridinium surfaces showed enhanced antibacterial activity compared to their nonfluorinated counterparts. Even a polymer with a relatively low molecular weight pyridinium block showed high antimicrobial activity. The bactericidal effect was found to be related to the molecular composition and organization in the top 2-3 nm of the surface and increased with increasing hydrophilicity and pyridinium concentration of the surface.

  10. Assessment of bromide-based ionic liquid toxicity toward aquatic organisms and QSAR analysis.

    PubMed

    Wang, Chao; Wei, Zhongbo; Wang, Liansheng; Sun, Ping; Wang, Zunyao

    2015-05-01

    The toxicities of 24 bromide-based ionic liquids (Br-ILs) towards Vibrio fischeri (V. fischeri) and Daphnia magna (D. magna) were determined. These Br-ILs are composed of a bromide ion and a generic cation (i.e., pyrrolidinium, piperidinium, pyridinium or imidazolium) with different alkyl side chains. QSAR models with relatively high correlation coefficients, R(2), of 0.954 and 0.895 were developed for V. fischeri and D. magna. The model for V. fischeri indicated that the Br-IL toxicity towards V. fischeri was negatively correlated with the energy of the lowest unoccupied molecular orbitals (ELUMO) which reflects the electron affinities (EAs) and positively correlated with the volumes of Br-IL cations. For the D. magna model, the Br-IL toxicity was positively correlated with the dipole moment (μ) and negatively correlated with the total energy (TE) that is highly correlated with the molecular volume (V). For Br-ILs with the same cation ring, the toxicity increased as the length of the alkyl chains increased. For the same alkyl chain length, the toxicity order for V. fischeri was pyridinium>imidazolium>piperidinium>pyrrolidinium, except for those containing octyl side chains, while the toxicity ranking for D. magna was imidazolium~pyridinium>piperidinium>pyrrolidinium. PMID:25682588

  11. Preferred gauche conformation in N-(2-aminoethyl)pyridinium ions

    NASA Astrophysics Data System (ADS)

    Razenberg, Johannes A. S. J.; Nolte, Roeland J. M.; Drenth, Wiendelt; Kanters, Jan A.; Van Duijneveldt, Frans B.

    1984-01-01

    X-ray analysis of 1-[(2 S, 3 S)-2- N,N-dibenzylamino-3-methyl-1-pentyl]pyridinium p-toluenesulphonate and 1-[(2 S)-2- N,N-dibenzylamino-1-propyl]pyridinium p-toluenesulphonate reveals that in both compounds the central NCCN moiety is in the syn-clinal conformation. According to SCF-LCAO-MO calculations the syn-clinal conformation of the parent on, N-(2-aminomethyl)pyridinium is 23.4 kJ mol -1 lower in energy than the anti-periplanar conformation. The calculations suggest incipient bond formation between the amino nitrogen atom and the pyridinium ring in the syn-clinal conformation.

  12. Synthesis of indoles from pyridinium salts

    SciTech Connect

    Gromov, S.P.; Bkhaumik, M.M.; Bundel', Yu.G.

    1987-10-01

    The detailed analysis of the products of the interaction of nitropyridinium salts with ketones and alkylamines resulted in new data testifying in favor of the previously proposed scheme for the formation of indoles from pyridinium salts. The PMR spectra were taken on a Bruker WM-500 spectrometer for the compounds (IXa,b) in CDCl/sub 3/, and (IVg, i-Z) in acetone-D/sub 6/, and a Varian T-60 spectrometer for the alkylindoles (IVa,c,h) in CDCl/sub 3/, with reference to HMDS. The /sup 13/C NMR spectra were taken on a Bruker WM-250 spectrometer in CDCl/sub 3/. The mass spectra were taken on a Finnigan-4021 instrument.

  13. QSPR CORRELATION OF THE MELTING POINT FOR PYRIDINIUM BROMIDES, POTENTIAL IONIC LIQUIDS. (R828257)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  14. [Quantitative aspects of the percutaneous uptake of wool wax alcohols (cetyl alcohol) and paraffins (octadecane) from different ointment bases].

    PubMed

    Zesch, A; Bauer, E

    1985-01-01

    Since topical vehicles are partly responsible for the effects of active agents--both the wanted and the unwanted effects--attempt was made to obtain quantitative data on the possible penetration of cetyl alcohol contained in an aqueous hydrophilie cream (DAB 8) and in a wool fat alcohol ointment (lanoline) (DAB 8). Also the behaviour of the long-chained hydrocarbon, paraffin (octadecan), in these vehicles and in petrolatum (DAB 8) was studied. We found that the emulsifying agent in a W/O emulsion was detectable in the epidermis in low concentrations after 100 min, but the same agent in O/W emulsions only after 1000 min. It is, therefore, unlikely that cetyl alcohol penetrates the intact skin in allergicologically relevant concentrations. However, with diseased skin, a marked percutaneous absorption of cetyl alcohol, but not with paraffin, must be expected. PMID:3987517

  15. The effect of cetylated fatty esters and physical therapy on myofascial pain syndrome of the neck.

    PubMed

    Sharan, Deepak; Jacob, Biju Nirmal; Ajeesh, P S; Bookout, Jack B; Barathur, Raj R

    2011-07-01

    Participants with Myofascial Pain Syndrome (MPS) of the neck were randomly assigned into 2 groups of the double-blinded study: topical cetylated fatty ester complex (CFEC) cream application plus physical therapy (CF-PT; n=37), and placebo cream application plus physical therapy (PL-PT; n=35). There were 3 visits during 4 weeks of treatment. Physical Therapy (PT), given twice/week, included Ischaemic Compression, Deep Pressure Trigger Point Massage and Myofascial Releases. Topical cream [CFEC cream (5.6%) and 1.5% menthol] or placebo cream [1.5% menthol, in a cream base] was applied twice/day. CF-PT provided the fastest and most effective study treatment modality. The addition of CFEC cream to PT resulted in statistically significant improvements, compared to PL-PT, for reduction of pain, neck disability and life quality indicators. Our results indicate that cetylated derivatives of fatty acids can effectively reduce pain and symptoms associated with neck MPS, when combined with physical therapy. PMID:21665114

  16. Lipase catalysed synthesis of cetyl oleate using ultrasound: Optimisation and kinetic studies.

    PubMed

    Khan, Nishat R; Jadhav, Sachin V; Rathod, Virendra K

    2015-11-01

    The current paper exemplifies the application of ultrasound technology to enzymatic synthesis of a cosmetic emollient ester, cetyl oleate. Fermase CALB™10000, a commercial Candida antarctica lipase B was used as a catalyst to accomplish the ultrasound supported synthesis. Multiple process parameters like reaction time, temperature, enzyme dose, alcohol to acid molar ratio, ultrasound power, frequency and speed of agitation were optimised. Maximum conversion of ∼95.96% was discerned at optimum conditions, i.e., 60°C temperature, 5% enzyme dose, 2:1 alcohol:acid ratio, 60 W ultrasound power, 25 kHz ultrasound frequency, 80% duty cycle and 80 rpm speed of agitation after purification steps. It was observed that the reaction reached equilibrium in a short duration of 30 min under the optimised conditions. This was considerably lesser than the time required for attaining equilibrium in conventional mechanical stirring method which was over 2h. Bisubstrate kinetic models like random bi-bi, ping pong bi-bi and ordered bi-bi were applied to the experimental data to determine initial rates and other kinetic parameters. Ordered bi-bi model showed the best fit with kinetic parameters, Vmax=0.029 M/min/gcatalyst, KA=0.00001 M, KB=4.8002 M, KiA=0.00014 M, KiB=3.7914 M & SSE=0.00022 for enzymatic cetyl oleate synthesis under ultrasound irradiation with inhibition by both acid and alcohol at high concentrations. PMID:25913878

  17. Copper-Catalyzed Annulation: A Method for the Systematic Synthesis of Phenanthridinium Bromide.

    PubMed

    Jhang, Yuan-Ye; Fan-Chiang, Tai-Ting; Huang, Jun-Min; Hsieh, Jen-Chieh

    2016-03-01

    A novel procedure for the Cu-catalyzed systematic synthesis of phenanthridinium bromide is reported. This transformation was achieved with direct construction of central pyridinium core by using an in situ formed biaryl imine as a substrate. Tolerance of a very wide variety of N-substituents is indicated; this has never previously been disclosed by other reports. Application of this method to synthesis of the natural alkaloid bicolorine, and its derivatives, was also carried out in only three synthetic steps from commercially available compounds. PMID:26883677

  18. Magnetochemistry of the tetrahaloferrate (III) ions. 7. Crystal structure and magnetic ordering in (pyridinium){sub 3}Fe{sub 2}Br{sub 9}

    SciTech Connect

    Lowe, C.B.; Shaviv, R.; Carlin, R.L.

    1994-07-06

    A monoclinic crystal structure was found by X-ray diffraction for bis [pyridinium tetrabromferrate(III)]-pyridinium bromide. The double salt contains two slightly distorted [FeBr{sub 4}]{sup -} tetrahedra, three pyridinium rings, and an uncoordinated halide in each asymmetric unit, as is characteristic of the A{sub 3}Fe{sub 2}X{sub 9} series of compounds. Unit cell parameters, monoclinic space group P2{sub 1}, are a = 7.656(3) {angstrom}, b = 14.237(5) {angstrom}, c = 13.725(5) {angstrom}, {beta} = 93.42(3){degrees}, and V = 1493(1) {angstrom}{sup 3}, using Mo K{alpha} radiation {lambda} = 0.710 69 {angstrom}, {rho}{sub calc} = 2.38 g cm{sup -3}, and Z = 2. The tetrahedra are aligned with their 3-fold axes parallel to the crystallographic c axis. Bond lengths (Fe-Br) range from 2.271(9) {angstrom} to 2.379(9) {angstrom} for the two different slightly distorted tetrahedral units. Magnetic susceptibility studies show that the material orders three-dimensionally at 7.4 {+-} 0.2 K. The data are compared to a HTS expansion of 1/{sub {chi}} for the S = 5/2 three-dimensional Heisenberg model antiferromagnet for a sc lattice with g = 1.98 and J/k{sub B} = -0.43 K. The specific heat measurements indicate two odd-shaped {lambda} features, at 7.3 and 8 K.

  19. Solvent-Directed Assembly of a Pyridinium-Tailored Methyl Oleanolate Amphiphile: Stepwise Growth of Microrods and Nanofibers.

    PubMed

    Gao, Yuxia; Hao, Jie; Wu, Jindan; Zhang, Xun; Hu, Jun; Ju, Yong

    2016-02-23

    Although a few architectures have been fabricated by the self-assembly of natural triterpenoids, the precise control of shape and size is rarely studied. Herein, a methyl oleanolate-bearing amphiphile, 1-[2-(methyl oleanolate)-2-oxoethyl]pyridinium bromide (MOP), has been designed and its assembly behavior was investigated. It was found that the morphologies of MOP assemblies ranged from nanoparticles to rigid microrods and flexible nanofibers in chloroform/p-xylene and methanol/water, respectively. During the assembly process, the systematical variational solvophobic/solvophilic effect resulted in the formation of spherical nanoparticles with opposite dipoles and converse bilayer structures. Moreover, such opposite molecular orientations lead to the inversion of supramolecular chirality and distinct mechanical properties. The driving forces and packing patterns of MOP in each solvent system were clearly demonstrated by the combination of NMR, UV-vis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), theoretical computation, and contact angle experiments, which revealed the roles of triterpenoids and pyridinium cations in the assembly process. This work provides a facile strategy to control the supramolecular structures in triterpenoid-based assemblies by adjusting the solvent polarity and composition. PMID:26829548

  20. Synthesis and antibacterial activity of pyridinium-tailored aromatic amphiphiles.

    PubMed

    Wang, Peiyi; Gao, Manni; Zhou, Lei; Wu, Zhibing; Hu, Deyu; Hu, Jun; Yang, Song

    2016-02-15

    In this Letter, the antibacterial activities of pyridinium-tailored aromatic amphiphiles were evaluated by turbidimeter tests in vitro. The bioassays revealed that most of the target compounds exhibit appreciable inhibition activities against the plant pathogenic bacteria Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas axonopodis pv. citri. The half-maximal effective concentrations (EC50) of 2-NP-10, 9-AP-10, and 9-AP-7 against these three bacteria were relatively high, which may be ascribed to the favourable hydrophobicity/hydrophilicity balance in these compounds. Our results suggest that pyridinium-tailored aromatic amphiphiles are promising bactericide candidates against plant bacterial diseases. PMID:26832217

  1. Bromide affecting drinking water mutagenicity.

    PubMed

    Myllykangas, T; Nissinen, T K; Mäki-Paakkanen, J; Hirvonen, A; Vartiainen, T

    2003-11-01

    The effect of bromide on the mutagenicity of artificially recharged groundwater and purified artificially recharged groundwater after chlorine, ozone, hydrogen peroxide, permanganate, and UV treatments alone and in various combinations was studied. The highest mutagenicity was observed after chlorination, while hydrogen peroxide-ozone-chlorine treatment produced the lowest value for both waters. Chlorinated waters, which were spiked with bromide, had up to 3.7 times more mutagenic activity than waters without bromide after every preoxidation method. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was found to correspond as much as 76% of the overall mutagenicity in the waters not spiked with bromide. MX formation was found to be lower when the treated water contained bromide, implicating the formation of brominated MX analogues. Trihalomethane formation increased when the treated water contained bromide. PMID:13129514

  2. Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.

    PubMed

    Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario

    2014-12-01

    The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions. PMID:25326892

  3. Action of reactive oxygen species in the antifungal mechanism of gemini-pyridinium salts against yeast.

    PubMed

    Shirai, Akihiro; Ueta, Shouko; Maseda, Hideaki; Kourai, Hiroki; Omasa, Takeshi

    2012-06-01

    We previously found that the gemini quaternary salt (gemini-QUAT) containing two pyridinium residues per molecule, 3,3'- (2,7-dioxaoctane) bis (1-decylpyridinium bromide) (3DOBP-4,10) , exerted fungicidal activity against Saccharomyces cerevisiae and caused respiration inhibition and the cytoplasmic leakage of ATP, magnesium, and potassium ions. Here, we investigated how the gemini-QUAT, 3DOBP-4,10, exerts more powerful antimicrobial activity than the mono-QUAT N-cetylpyridinium chloride (CPC) and examined the association between reactive oxygen species (ROS) and the antimicrobial mechanism. Antifungal assays showed that the activity of 3DOBP-4,10 against two yeasts, S. cerevisiae and Candida albicans, was significantly elevated under aerobic conditions, and largely reduced under anaerobic conditions (nitrogen atmosphere) . Adding radical scavengers such as superoxide dismutase, catalase and potassium iodide (KI) also decreased the fungicidal activity of 3DOBP-4,10 but negligibly affected that of CPC. We measured survival under static conditions and found that the rapid fungicidal profile of 3DOBP-4,10 was lost, whereas that of CPC was slightly affected in the presence of KI. Our results suggest that 3DOBP-4,10 exerts powerful antimicrobial activity by penetrating the cell wall and membrane, which then allows oxygen to enter the cells, where it participates in the generation of intracellular ROS. The activity could thus be attributable to a synergic antimicrobial combination of the disruption of organelle membranes by the QUAT and oxidative stress imposed by ROS. PMID:22790843

  4. Condensed pyridines. 6. Synthesis and structure of adamantyl-, cyclopropyl- and alkyl-substituted 3-halomethyl-2,3-dihydro-8-cyanothiazolo(3,2-a)pyridinium salts and their oxazolo and selenazolo derivatives

    SciTech Connect

    Litvinov, V.P.; Sharanin, Yu.A.; Apenoeva, E.E.; Shestopalov, A.M.; Mortikov, V.Yu.; Nesterov, V.N.; Shklover, V.E.; Struchkov, Yu.T.

    1987-11-01

    The reaction of substituted 2-cyanopyridin-2(1H)-ones and their thione and selenone derivatives with allyl bromide gives the corresponding 2-allyloxy-, 2-allylmercapto-, and 2-allylseleno-3-pyridines, which upon treatment with halogens, form intramolecular quaternization products, namely, 3-halomethyl-2,3-dihydro-8-cyanooxazole(3,2-a)pyridinium salts and their thiazolo and selen-azolo analogs. X-ray diffraction structural analysis was used to determine the structure of 3-bromomethyl-2,3-dihydro-5,7-dimethyl-8-cyanothiazolo(3,2-a)pyridinium perchlorate. The IR spectra were taken in KBr pellets on a UR-20 spectrometer. The UV spectra were taken on a Specord UV-vis spectrometer in ethanol and DMF. The PMR spectra were taken on a Bruker WM-250 spectrometer at 250 MHz in CDCl/sub 3/ and DMSO-d/sub 6/ with TMS as the internal standard.

  5. Development of cetyl dimethicone based water-in-oil emulsion containing botanicals: Physical characteristics and stability.

    PubMed

    Waqas, Muhammad Khurram; Akhtar, Naveed; Shah, Pervaiz Akhtar; Danish, Muhammad Zeeshan; Shah, Arshad Ali; Braga, Valdir de Andrade; Khan, Barkat Ali

    2016-01-01

    The aim of current research was to develop a water-in-oil emulsion containing grape seed extract for application in cosmeceuticals. Finally grinded dried grape seeds powder was extracted with hydro alcoholic mixture. Emulsions consisting of different concentrations of cetyl dimethicone (Abile EM90), the nonionic emulsifier, liquid paraffin as oily phase and water as aqueous phase were developed. Color, odor, pH, viscosity, liquefaction, phase separation, centrifugation and thermal stability of the formulated emulsions were observed at various storage temperatures i.e. 8±0.5°C, 25±0.5°C, 40±0.5°C and 40°C±0.5°C with 70% RH. The stable formulation consist of 16% mineral oil, 4% of ABIL EM 90(®), 4% grape seeds extract, 1% rose oil and 75% distilled water. All the results derived from this study showed good stability over the three months study period which indicates w/o emulsion can be used as carrier of 4% grape seeds extract to enhance desired effects when applied topically. PMID:26826810

  6. High Yield of Wax Ester Synthesized from Cetyl Alcohol and Octanoic Acid by Lipozyme RMIM and Novozym 435

    PubMed Central

    Kuo, Chia-Hung; Chen, Hsin-Hung; Chen, Jiann-Hwa; Liu, Yung-Chuan; Shieh, Chwen-Jen

    2012-01-01

    Wax esters are long-chain esters that have been widely applied in premium lubricants, parting agents, antifoaming agents and cosmetics. In this study, the biocatalytic preparation of a specific wax ester, cetyl octanoate, is performed in n-hexane using two commercial immobilized lipases, i.e., Lipozyme® RMIM (Rhizomucor miehei) and Novozym® 435 (Candida antarctica). Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) are employed to evaluate the effects of reaction time (1–5 h), reaction temperature (45–65 °C), substrate molar ratio (1–3:1), and enzyme amount (10%–50%) on the yield of cetyl octanoate. Using RSM to optimize the reaction, the maximum yields reached 94% and 98% using Lipozyme® RMIM and Novozym® 435, respectively. The optimum conditions for synthesis of cetyl octanoate by both lipases are established and compared. Novozym® 435 proves to be a more efficient biocatalyst than Lipozyme® RMIM. PMID:23109878

  7. Aqueous Zinc Bromide Waste Solidification

    SciTech Connect

    Langton, C.A.

    2002-07-23

    The goal of this study was to select one or more commercially available aqueous sorbents to solidify the zinc bromide solution stored in C-Area, identify the polymer to zinc bromide solution ratio (waste loading) for the selected sorbents, and identify processing issues that require further testing in pilot-scale testing.

  8. Tiotropium Bromide: An Update

    PubMed Central

    Heredia, Josep Lluis

    2009-01-01

    Tiotropium bromide is a once-daily inhaled anticholinergic bronchodilator. It works by blocking the muscarinic receptors in airway smooth muscle. Tiotropium has a wide therapeutic margin, due to its poor gastrointestinal absorption and its very low systemic bioavailability. The drug is mainly indicated in COPD patients. Clinically relevant outcomes such as significant improvements in spirometry, hyperinflation, dyspnea, heath status, acute exacerbations and mortality have been consistently observed in tiotropium clinical trials, and the drug has been shown to reduce the risk of mortality due to cardiac-vascular disease and respiratory failure. The main side effect reported is dryness of the mouth. Some subgroups of asthmatics also seem to respond to anticholinergic drugs: among them, those with the Arg/Arg genotype for the β2-adrenergic receptor and those with a high percentage of neutrophils in sputum. PMID:19461900

  9. N-Acetyl Cysteine (NAC)-Directed Detoxification of Methacryloxylethyl Cetyl Ammonium Chloride (DMAE-CB)

    PubMed Central

    Shan, Lequn; Wang, Yingjie; Tian, Min; Yang, Yanwei; Sun, Jinlong; Ban, Jinghao; Chen, Jihua

    2015-01-01

    Methacryloxylethyl cetyl ammonium chloride (DMAE-CB) is a polymerizable antibacterial monomer and has been proved as an effective strategy to achieve bioactive bonding with reliable bacterial inhibitory effects. However, the toxicity of DMAE-CB may hamper its wide application in clinical situations. Thus, this study was designed to investigate the toxicity of DMAE-CB and explore the possible protective effects of N-acetyl cysteine (NAC). High performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) analysis showed that chemical binding of NAC and DMAE-CB occurred in a time dependent manner. Pre-incubation of fourty-eight hours is required for adequate reaction between DMAE-CB and NAC. DMAE-CB reduced human dental pulp cells (hDPCs) viability in a dose-dependent manner. The toxic effects of DMAE-CB were accompanied by increased reactive oxygen species (ROS) level and reduced glutathione (GSH) content. NAC alleviated DMAE-CB-induced oxidative stress. Annexin V/ Propidium Iodide (PI) staining and Hoechst 33342 staining indicated that DMAE-CB induced apoptosis. Collapsed mitochondrial membrane potential (MMP) and activation of caspase-3 were also observed after DMAE-CB treatment. NAC rescued hDPCs from DMAE-CB-induced apoptosis, accompanied by lower level of MMP loss and caspase-3 activity. This study assists to elucidate the mechanism underlying the cytotoxic effects of DMAE-CB and provides theoretical supports for the searching of effective strategies to reduce toxicity of quaternary ammonium dental monomers. PMID:26274909

  10. Method for making aromatic ethers using diorganoamino pyridinium salt catalyst

    SciTech Connect

    Brunelle, D. J.; Singleton, D. A.

    1985-04-23

    A method is provided for making aromatic ethers by effecting the displacement of reactive radicals on an activated aromatic nucleus such as a phthalimide with a mono or bisalkali metal phenoxide in the presence of an organic solvent and a dialkylamino branched alkyl substituted pyridinium salt as a phase transfer catalyst. Improved yields of bis(aromatic ethers) are achieved without the production of undesirable by-products, such as alkylated phenols.

  11. Epoxy nanocomposites based on high temperature pyridinium-modified clays.

    PubMed

    Zhang, Qingxin; Naito, Kimiyoshi; Qi, Ben; Kagawa, Yutaka

    2009-01-01

    Polymer/clay nanocomposites are generally fabricated by thermal curing or melt compounding at elevated temperatures, however the thermal stability of common alkyl ammonium treated clays is poor and decomposition occurs inevitably during high temperature processing. In this study, we modified clays with an aromatic pyridinium salt. Thermogravimetric analysis (TGA) showed that the onset degradation temperature (Td(onset)) and maximum decomposition temperature (Td(max)) of the pyridinium treatment clays was up to 310 and 457 degrees C respectively implying high thermal stability. The thermal decomposition behaviour of the pyridinium modified clays was discussed. A series of epoxy/clay nanocomposites were synthesized using a diglycidyl ether of bisphenol A (DGEBA) epoxy and diethyltoluene diamine (DETDA). The morphology of epoxy/clay nanocomposites was characterized with wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM), and intercalated structures were observed. The storage modulus of epoxy was increased but glass transition temperature was decreased with clay incorporation. The effects of clays on glass transition temperature (Tg) of epoxy were also discussed. PMID:19441298

  12. Efficient and synergetic DNA delivery with pyridinium amphiphiles-gold nanoparticle composite systems having different packing parameters.

    PubMed

    Kizewski, Adrian; Ilies, Marc A

    2016-01-01

    Mixtures of highly curved pyridinium-decorated Au nanoparticles and standard pyridinium cationic lipids efficiently and synergetically transfected DNA in vitro, while displaying an excellent cytotoxic profile. PMID:26553432

  13. Investigation of the Pyridinium Ylide--Alkyne Cycloaddition as a Fluorogenic Coupling Reaction.

    PubMed

    Bonte, Simon; Ghinea, Ioana Otilia; Dinica, Rodica; Baussanne, Isabelle; Demeunynck, Martine

    2016-01-01

    The cycloaddition of pyridinium ylides with alkynes was investigated under mild conditions. A series of 13 pyridinium salts was prepared by alkylation of 4-substituted pyridines. Their reactivity with propiolic ester or amide in various reaction conditions (different temperatures, solvents, added bases) was studied, and 11 indolizines, with three points of structural variation, were, thus, isolated and characterized. The highest yields were obtained when electron-withdrawing groups were present on both the pyridinium ylide, generated in situ from the corresponding pyridinium salt, and the alkyne (X, Z = ester, amide, CN, carbonyl, etc.). Electron-withdrawing substituents, lowering the acid dissociation constant (pKa) of the pyridinium salts, allow the cycloaddition to proceed at pH 7.5 in aqueous buffers at room temperature. PMID:26978335

  14. Ultraviolet photodissociation action spectroscopy of the N-pyridinium cation

    SciTech Connect

    Hansen, Christopher S. Trevitt, Adam J.; Blanksby, Stephen J.; Chalyavi, Nahid; Bieske, Evan J.; Reimers, Jeffrey R.

    2015-01-07

    The S{sub 1}←S{sub 0} electronic transition of the N-pyridinium ion (C{sub 5}H{sub 5}NH{sup +}) is investigated using ultraviolet photodissociation (PD) spectroscopy of the bare ion and also the N{sub 2}-tagged complex. Gas-phase N-pyridinium ions photodissociate by the loss of molecular hydrogen (H{sub 2}) in the photon energy range 37 000–45 000 cm{sup −1} with structurally diagnostic ion-molecule reactions identifying the 2-pyridinylium ion as the exclusive co-product. The photodissociation action spectra reveal vibronic details that, with the aid of electronic structure calculations, support the proposal that dissociation occurs through an intramolecular rearrangement on the ground electronic state following internal conversion. Quantum chemical calculations are used to analyze the measured spectra. Most of the vibronic features are attributed to progressions of totally symmetric ring deformation modes and out-of-plane modes active in the isomerization of the planar excited state towards the non-planar excited state global minimum.

  15. Ultraviolet photodissociation action spectroscopy of the N-pyridinium cation

    NASA Astrophysics Data System (ADS)

    Hansen, Christopher S.; Blanksby, Stephen J.; Chalyavi, Nahid; Bieske, Evan J.; Reimers, Jeffrey R.; Trevitt, Adam J.

    2015-01-01

    The S1←S0 electronic transition of the N-pyridinium ion (C5H5NH+) is investigated using ultraviolet photodissociation (PD) spectroscopy of the bare ion and also the N2-tagged complex. Gas-phase N-pyridinium ions photodissociate by the loss of molecular hydrogen (H2) in the photon energy range 37 000-45 000 cm-1 with structurally diagnostic ion-molecule reactions identifying the 2-pyridinylium ion as the exclusive co-product. The photodissociation action spectra reveal vibronic details that, with the aid of electronic structure calculations, support the proposal that dissociation occurs through an intramolecular rearrangement on the ground electronic state following internal conversion. Quantum chemical calculations are used to analyze the measured spectra. Most of the vibronic features are attributed to progressions of totally symmetric ring deformation modes and out-of-plane modes active in the isomerization of the planar excited state towards the non-planar excited state global minimum.

  16. Interaction of Lucifer yellow with cetyltrimethyl ammonium bromide micelles and the consequent suppression of its non-radiative processes

    NASA Astrophysics Data System (ADS)

    Mishra, Padmaja P.; Koner, Apurba L.; Datta, Anindya

    2004-12-01

    The interaction of the fluorophore Lucifer yellow with micelles has been monitored using steady state and time resolved fluorescence techniques. Contrary to the popular belief that the fluorophore is too polar to associate with the stern layer or hydrophobic core of micelles, we have observed that it binds with the micelles of the positively charged surfactant cetyl trimethyl ammonium bromide and that such interaction causes an decrease in the rates of its non-radiative processes. This phenomenon cannot be explained solely in the light of a reduced polarity, as we have demonstrated that the photophysics of Lucifer yellow is complex and intramolecular charge transfer does not seem to be the only excited state process that is operative.

  17. Mechanistic studies of pyridinium electrochemistry: alternative chemical pathways in the presence of CO2.

    PubMed

    Peroff, A G; Weitz, E; Van Duyne, R P

    2016-01-21

    Protonated heterocyclic amines, such as pyridinium, have been utilized as catalysts in the electrocatalytic reduction of carbon dioxide. While these represent a new and exciting class of electrocatalysts, the details of the mechanism and faradaic processes occurring in solution are unclear. We report a series of cyclic voltammetry experiments involving Pt, Ag, Au, and Cu electrodes, under both aqueous and nonaqueous conditions, directed towards gaining an improved mechanistic understanding of pyridinium electrochemistry. Surface-enhanced Raman (SER) spectroelectrochemistry was also performed on Cu film-over-nanosphere electrodes in order to identify adsorbed species. It was found that the reduction potential of pyridinium (-0.58 V vs. SCE) and its electrochemical reversibility are unique features of platinum electrodes. In contrast, the reduction potentials on Ag, Au, and Cu electrodes are ∼400 mV more negative than Pt in both the presence and the absence of CO2. SER spectroelectrochemistry of pyridinium solutions shows no evidence for a pyridinium radical or a pyridinium ion. Increased cathodic current in the presence of CO2 is only detected at scan rates less than 10 mV s(-1) in aqueous solutions. The addition of CO2 resulted in a shift in the potential for the hydrogen evolution reaction. Pyridinium electrochemistry was observed under nonaqueous conditions; however no increase in cathodic current was observed when CO2 was added to the solution. Based on this set of results it is concluded that the reduction potential of pyridinium is surface dependent, CO2 acts as a pseudo-reserve of H(+), and pyridinium and CO2 create an alternative mechanism for hydrogen evolution. PMID:26670579

  18. Two Equilibria of (N-Methyl-3-pyridinium)chlorocarbene, a Cationic Carbene.

    PubMed

    Cang, Hui; Moss, Robert A; Krogh-Jespersen, Karsten

    2016-02-11

    Equilibrium constants and the associated thermodynamic parameters are reported for the equilibria established between the cationic carbene (N-methyl-3-pyridinium)chlorocarbene tetrafluoroborate (MePyr(+)CCl BF4(-), 3) and 1,3,5-trimethoxybenzene (TMB) to form a carbene-TMB complex, as well as between carbene 3 and chloride ion to form the zwitterion, N-methyl-3-pyridinium dichloromethide (10). These equilibrium constants and thermodynamic parameters are contrasted with analogous data for several related carbenes, and the influence of the pyridinium unit in carbene 3 is thereby highlighted. Computational studies augment and elucidate the experimental results. PMID:26830199

  19. Bromide Adsorption by Reference Minerals and Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bromide, Br-, adsorption behavior was investigated on amorphous Al and Fe oxide, montmorillonite, kaolinite, and temperate and tropical soils. Bromide adsorption decreased with increasing solution pH with minimal adsorption occurring above pH 7. Bromide adsorption was higher for amorphous oxides t...

  20. Mini review on blood-brain barrier penetration of pyridinium aldoximes.

    PubMed

    Kalász, H; Nurulain, S M; Veress, G; Antus, S; Darvas, F; Adeghate, E; Adem, A; Hashemi, F; Tekes, K

    2015-02-01

    This paper reviews the blood-brain barrier (BBB) penetration of newly developed pyridinium aldoximes. Pyridinium aldoximes are highly charged hydrophilic compounds used in the treatment of subjects exposed to organophosphonates because they are effective as acetylcholinesterase reactivators. Pyridinium aldoximes have antidotal effects against poisoning with cholinesterase inhibitors, a frequent problem affecting people working with organophosphate-based insecticides and pesticides. Toxic organophosphonate products such as sarin and tabun can be used by terrorists as chemical warfare agents. This poses a severe challenge to all innocent and peace-loving people worldwide. This review gives a brief summary of BBB transporters and description of the current in vitro and in vivo methods for the characterization of BBB penetration of established and novel pyridinium aldoximes. The authors provide a putative mechanism of penetration, outline some future ways of formulation and discuss the possible advantages and disadvantages of increasing BBB penetration. PMID:25291712

  1. 2-Amino-5-methyl-pyridinium 4-chloro-benzoate.

    PubMed

    Thanigaimani, Kaliyaperumal; Farhadikoutenaei, Abbas; Arshad, Suhana; Razak, Ibrahim Abdul

    2013-01-01

    The 4-chloro-benzoate anion of the title salt, C6H9N2(+)·C7H4ClO2(-), is nearly planar with a dihedral angle of 5.14 (16)° between the benzene ring and the carboxyl-ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms of the anion via a pair of N-H⋯O hydrogen bonds with an R2(2)(8) ring motif. The ion pairs are further connected via N-H⋯O and weak C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. The crystal structure also features a π-π stacking inter-action between the pyridinium and benzene rings with a centroid-centroid distance of 3.7948 (9) Å. PMID:23476392

  2. 2-Amino-6-methyl-pyridinium 3-chloro-benzoate.

    PubMed

    Thanigaimani, Kaliyaperumal; Khalib, Nuridayanti Che; Arshad, Suhana; Razak, Ibrahim Abdul

    2013-03-01

    In the title salt, C6H9N2(+)·C7H4ClO2(-), the 3-chloro-benzoate anion shows a whole-mol-ecule disorder over two positions with a refined occupancy ratio of 0.505 (4):0.495 (4). In the crystal, the cations and anions are linked via N-H⋯O hydrogen bonds, forming a centrosymmetric 2 + 2 aggregate with R2(2)(8) and R4(2)(8) ring motifs. The crystal structure also features a π-π stacking inter-action between the pyridinium rings with a centroid-centroid distance of 3.8339 (9) Å. PMID:23476517

  3. 2-Amino-5-methyl-pyridinium 4-methyl-benzoate.

    PubMed

    Thanigaimani, Kaliyaperumal; Farhadikoutenaei, Abbas; Arshad, Suhana; Razak, Ibrahim Abdul

    2013-01-01

    The 4-methyl-benzoate anion of the title salt, C6H9N2(+)·C8H7O2(-), is nearly planar, with a dihedral angle of 6.26 (10)° between the benzene ring and the carboxyl-ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms of the anion via a pair of N-H⋯O hydrogen bonds with an R2(2)(8) ring motif, forming an approximately planar ion pair with a dihedral angle of 9.63 (4)° between the pyridinium and benzene rings. The ion pairs are further connected via N-H⋯O and weak C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. PMID:23476474

  4. Reduction and alkaline hydrolysis of 5-oxoindeno(1,2-b)pyridinium salts

    SciTech Connect

    Mutsenietse, D.Kh.; Zandersons, A.Z.; Lusis, V.K.; Dubur, G.Ya.

    1987-07-01

    5,9b-dihydro derivatives of indeno(1,2-b)pyridine were obtained by the reduction of the corresponding 1,2-dimethyl-4-acryl-5-oxoindeno(1,2-b)pyridinium perchlorates. 1,2-dimethyl-3-ethoxycarbonyl-4-phenyl-5-oxoindeno(1,2-b)pyridinium perchlorate forms in alkaline medium with splitting, recyclization and deamination products.

  5. Lanthanum Bromide Detectors for Safeguards Measurements

    SciTech Connect

    Wright, J.

    2011-05-25

    Lanthanum bromide has advantages over other popular inorganic scintillator detectors. Lanthanum bromide offers superior resolution, and good efficiency when compared to sodium iodide and lanthanum chloride. It is a good alternative to high purity germanium detectors for some safeguards applications. This paper offers an initial look at lanthanum bromide detectors. Resolution of lanthanum bromide will be compared lanthanum chloride and sodium-iodide detectors through check source measurements. Relative efficiency and angular dependence will be looked at. Nuclear material spectra, to include plutonium and highly enriched uranium, will be compared between detector types.

  6. Structure and rheology of semisolid o/w creams containing cetyl alcohol/non-ionic surfactant mixed emulsifier and different polymers.

    PubMed

    Ribeiro, H M; Morais, J A; Eccleston, G M

    2004-04-01

    Oil-in-water (o/w) emulsions for cosmetic use, such as lotions and creams, are complex multiple-phase systems, which may contain a number of interacting surfactants, fatty amphiphiles, polymers and other excipients. This study investigates the influence of two synthetic cationic polymers, Polyquaternium-7 and Polyquaternium-11, and the natural anionic polymer, gum of acacia, on the rheology and microstructure of creams prepared with a non-ionic mixed emulsifier (cetyl stearyl alcohol-12EO/cetyl alcohol) using rheology (continuous shear, and viscoelastic creep and oscillation), microscopy and differential scanning calorimetry (DSC). A control cream containing no polymer was also investigated. The semisolid control cream was structured by a swollen lamellar gel network phase formed from the interaction of cetyl alcohol and the POE surfactant, in excess of that required to stabilize oil droplets, with continuous phase water. Endothermic transitions between 25 and 100 degrees C were identified as components of this phase. Incorporation of cationic polymer into the formulation caused significant loss of structure to produce a mobile semisolid containing larger oil droplets. The microscopical and thermal data implied that the cationic polymer caused the swollen lamellar gel network phase to transform into non-swollen crystals of cetyl alcohol. In contrast, incorporation of gum of acacia produced a thicker cream than the control, with smaller droplet sizes and little evidence of the gel network. Microscopical and thermal data implied that although there were also interactions between gum of acacia and both the surfactant and the swollen gel network phase, the semisolid properties were probably because of the ability of the gum of acacia to stabilize and thicken the emulsion in the absence of the swollen lamellar network. PMID:18494913

  7. Methacryloxylethyl Cetyl Ammonium Chloride Induces DNA Damage and Apoptosis in Human Dental Pulp Cells via Generation of Oxidative Stress

    PubMed Central

    Jiao, Yang; Ma, Sai; Wang, Yirong; Li, Jing; Shan, Lequn; Sun, Jinlong; Chen, Jihua

    2016-01-01

    The polymerizable antibacterial monomer methacryloxylethyl cetyl ammonium chloride (DMAE-CB) has provided an effective strategy to combat dental caries. However, the application of such material raises the question about the biological safety and the question remains open. The mechanism of this toxic action, however, is not yet clearly understood. The present study aims at providing novel insight into the possible causal link between cellular oxidative stress and DNA damage, as well as apoptosis in human dental pulp cells exposed to DMAE-CB. The enhanced formation of reactive oxygen species and depletion of glutathione, as well as differential changes in activities of superoxide dismutase, glutathione peroxidase, and catalase in DMAE-CB-treated cells indicated oxidative stress. By using substances that can alter GSH synthesis, we found that GSH was the key component in the regulation of cell response towards oxidative stress induced by DMAE-CB. The increase in oxidative stress-sensitive 8-Oxo-2'-deoxyguanosine (8-OHdG) content, formation of γ-H2AX and cell cycle G1 phase arrest indicated that DNA damage occurred as a result of the interaction between DNA base and ROS beyond the capacities of antioxidant mechanisms in cells exposed to DMAE-CB. Such oxidative DNA damage thus triggers the activation of ataxia telangiectasia-mutated (ATM) signaling, the intrinsic apoptotic pathway, and destruction of mitochondrial morphology and function. PMID:27143955

  8. Immobilized Rhizopus oryzae lipase catalyzed synthesis of palm stearin and cetyl alcohol wax esters: Optimization by Response Surface Methodology

    PubMed Central

    2011-01-01

    Background Waxes are esters of long-chain fatty acids and long-chain alcohols. Their principal natural sources are animals (sperm whale oil) and vegetables (jojoba) which are expensive and not easily available. Wax esters synthesized by enzymatic transesterification, using palm stearin as raw material, can be considered as an alternative to natural ones. Results Palm stearin is a solid fraction obtained by fractionation of palm oil. Palm stearin was esterified with cetyl alcohol to produce a mixture of wax esters. A non-commercial immobilized lipase from Rhizopus oryzae was used as biocatalyst. Response surface methodology was employed to determine the effects of the temperature (30-50°C), the enzyme concentration (33.34-300 IU/mL), the alcohol/palm stearin molar ratio (3-7 mol/mol) and the substrate concentration (0.06-0.34 g/mL) on the conversion yield of palm stearin. Under optimal conditions (temperature, 30°C; enzyme concentration, 300 IU/mL; molar ratio 3 and substrate concentration 0.21 g/mL) a high conversion yield of 98.52% was reached within a reaction time of 2 h. Conclusions Response surface methodology was successfully applied to determine the optimum operational conditions for synthesis of palm stearin based wax esters. This study may provide useful tools to develop economical and efficient processes for the synthesis of wax esters. PMID:21682865

  9. Methacryloxylethyl Cetyl Ammonium Chloride Induces DNA Damage and Apoptosis in Human Dental Pulp Cells via Generation of Oxidative Stress.

    PubMed

    Jiao, Yang; Ma, Sai; Wang, Yirong; Li, Jing; Shan, Lequn; Sun, Jinlong; Chen, Jihua

    2016-01-01

    The polymerizable antibacterial monomer methacryloxylethyl cetyl ammonium chloride (DMAE-CB) has provided an effective strategy to combat dental caries. However, the application of such material raises the question about the biological safety and the question remains open. The mechanism of this toxic action, however, is not yet clearly understood. The present study aims at providing novel insight into the possible causal link between cellular oxidative stress and DNA damage, as well as apoptosis in human dental pulp cells exposed to DMAE-CB. The enhanced formation of reactive oxygen species and depletion of glutathione, as well as differential changes in activities of superoxide dismutase, glutathione peroxidase, and catalase in DMAE-CB-treated cells indicated oxidative stress. By using substances that can alter GSH synthesis, we found that GSH was the key component in the regulation of cell response towards oxidative stress induced by DMAE-CB. The increase in oxidative stress-sensitive 8-Oxo-2'-deoxyguanosine (8-OHdG) content, formation of γ-H2AX and cell cycle G1 phase arrest indicated that DNA damage occurred as a result of the interaction between DNA base and ROS beyond the capacities of antioxidant mechanisms in cells exposed to DMAE-CB. Such oxidative DNA damage thus triggers the activation of ataxia telangiectasia-mutated (ATM) signaling, the intrinsic apoptotic pathway, and destruction of mitochondrial morphology and function. PMID:27143955

  10. Ionic Vapor Composition in Pyridinium-Based Ionic Liquids.

    PubMed

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-05-26

    Strong electrostatic interactions in ionic compounds make vaporization a complex process. The gas phase can contain a broad range of ionic clusters, and the cluster composition can differ greatly from that in the liquid phase. Room-temperature ionic liquids (RTILs) constitute a complicated case due to their ionic nature, asymmetric structure, and a huge versatility of ions and ionic clusters. This work reports vapor-liquid equilibria and vapor compositions of butylpyridinium (BPY) RTILs formed with hexafluorophosphate (PF6), trifluoromethanesulfonate (TF), and bis(trifluoromethanesulfonyl)imide (TFSI) anions. Unlike inorganic crystals, the pyridinium-based RTILs contain significant percentages of charged clusters in the vapor phase. Ion triplets and ion quadruplets each constitute up to 10% of the vapor phase composition. Triples prevail over quadruples in [BPY][PF6] due to the size difference of the cation and the anion. The percentage of charged ionic clusters in the gas phase is in inverse proportion to the mass of the anion. The largest identified vaporized ionic cluster comprises eight ions, with a formation probability below 1%. Higher temperature fosters formation of larger clusters due to an increase of the saturated vapor density. PMID:27165866

  11. Spectroscopic Studies of Imidizolium and Pyridinium Based Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Booth, Ryan; Stearns, Jaime

    2015-03-01

    Ionic liquids (ILs) have been shown to be extremely useful in areas ranging from chemical synthesis to energetic materials. Furthermore, ILs are thought to be a potential replacement for hydrazine as satellite propellants because a subset are hypergolic with nitric acid. While ILs are useful, however, there is a lack of understanding of the microscopic origins for their macroscopic properties (e.g. viscosity). An example of this is that [emim+][tf2N-] is three times less viscous than its methylated counterpart [emmim+][tf2N-] and there is some discord regarding the reason. We have investigated the molecular properties of such IL pairs using UV and IR spectroscopy in the gas phase on both imidozolium and pyridinium-based ([pyr+]) ILs. UV data show that the photophysics of [emmim+][tf2N-] is different than [emim+][tf2N-] in that there is a lack of evidence for the existence of a charge transfer (CT) state (as was seen in [emim+][tf2N-]). Preliminary UV spectra for the [pyr+] ILs show at least two distinct peaks in the region from 208-270 nm, which are tentatively established as CT states between the anion and cation. IR spectra deliver structural information for both sets of ILs and should provide insight into the correlation between microscopic and macroscopic properties.

  12. Reverse Anomeric Effect in Large-Amplitude Pyridinium Amide-Containing Mannosyl [2]Rotaxane Molecular Shuttles.

    PubMed

    Riss-Yaw, Benjamin; Waelès, Philip; Coutrot, Frédéric

    2016-06-17

    The reverse anomeric effect (RAE) was investigated in different mannosyl [2]rotaxane molecular shuttle isomers that contain dibenzo-24-crown-8 (DB24C8) as the macrocycle, and anilinium and pyridinium amide as molecular stations. The switching on or off of the RAE was possible depending on both the pyridinium amide motif and the localization of the DB24C8 along the thread. The (1) C4 mannopyranosyl chair-like conformation was observed in all the non-interlocked molecules because the anomeric carbon of the mannose is linked to the positively charged nitrogen of the pyridinium unit. In the protonated rotaxanes, the (1) C4 chair conformation of the mannose end remains because the DB24C8 resides around the best anilinium station, which is located at the other end of the axle. Upon deprotonation of the anilinium, the DB24C8 shuttles with a large-amplitude motion toward the pyridinium amide stations, where it interacts in a different fashion depending on the pyridinium motif. In one molecular shuttle, the RAE could be switched on or off with control at one end of the encircled thread upon protonation/deprotonation of the other end, through shuttling of the DB24C8. PMID:27062432

  13. Measuring methyl bromide emissions from fields

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.; Yates, M.V.

    1995-12-31

    Methyl bromide is used extensively for pest control. Recent evidence suggests that methyl bromide may react with stratospheric ozone and, due to the Clean Air Act, is scheduled for phase-out within the next 5 to 10 years. As indicated in a recent report from The National Agricultural Pesticide Impact Assessment Program, there will be substantial economic impact on the agricultural community if the use of methyl bromide is restricted. There are several areas of uncertainty concerning the agricultural use of methyl bromide. Foremost is the quantification of mass emitted to the atmosphere from agricultural fields. To address this, two field experiments were conducted to directly measure methyl bromide emissions. In the first experiment, methyl bromide was injected at approximately 25 cm depth and the soil was covered with 1 mil high-density polyethylene plastic. The second experiment was similar except that methyl bromide was injected at approximately 68 cm depth and the soil was not covered. From these experiments, the emission rate into the atmosphere and the subsurface transport of methyl bromide was determined. Both experiments include a field-scale mass balance to verify the accuracy of the flux-measurement methods as well as to check data consistency. The volatilization rate and mass lost was determined from estimates of the degradation and from several atmospheric and chamber flux methods.

  14. 77 FR 35295 - Methyl Bromide; Pesticide Tolerances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... AGENCY 40 CFR Part 180 RIN 2070-ZA16 Methyl Bromide; Pesticide Tolerances AGENCY: Environmental... methyl bromide in or on cotton, undelinted seed under the Federal Food, Drug, and Cosmetic Act (FFDCA.... Background In the Federal Register of April 6, 2012 (77 FR 20752) (FRL-9345- 1), EPA issued a proposed...

  15. METHYL BROMIDE ALTERNATIVES FOR VINEYARD REPLANT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation with methyl bromide is needed by grape growers in central California to control soilborne pests. However, use of methyl bromide is banned and soil fumigation with other chemicals subjects to strict regulations to protect human health and air quality. The objective was to determine,...

  16. Modulation of pyridinium cationic lipid-DNA complex properties by pyridinium gemini surfactants and its impact on lipoplex transfection properties.

    PubMed

    Sharma, Vishnu Dutt; Lees, Julia; Hoffman, Nicholas E; Brailoiu, Eugen; Madesh, Muniswamy; Wunder, Stephanie L; Ilies, Marc A

    2014-02-01

    The study presents the effects of blending a cationic gemini surfactant into cationic lipid bilayers and its impact on the plasmid DNA compaction and delivery process. Using nanoDSC, dynamic light scattering, zeta potential, and electrophoretic mobility measurements, together with transfection (2D- and 3D-) and viability assays, we identified the main physicochemical parameters of the lipid bilayers, liposomes, and lipoplexes that are affected by the gemini surfactant addition. We also correlated the cationic bilayer composition with the dynamics of the DNA compaction process and with transfection efficiency, cytotoxicity, and the internalization mechanism of the resultant nucleic acid complexes. We found that the blending of gemini surfactant into the cationic bilayers fluidized the supramolecular assemblies, reduced the amount of positive charge required to fully compact the plasmid DNA and, in certain cases, changed the internalization mechanism of the lipoplexes. The transfection efficiency of select ternary lipoplexes derived from cationic gemini surfactants and lipids was several times superior to the transfection efficiency of corresponding binary lipoplexes, also surpassing standard transfection systems. The overall impact of gemini surfactants into the formation and dynamic of cationic bilayers was found to depend heavily on the presence of colipids, their nature, and amount present in lipoplexes. The study confirmed the possibility of combining the specific properties of pyridinium gemini surfactants and cationic lipids synergistically to obtain efficient synthetic transfection systems with negligible cytotoxicity useful for therapeutic gene delivery. PMID:24377350

  17. Modulation of pyridinium cationic lipid-DNA complex properties by pyridinium gemini surfactants and its impact on lipoplex transfection properties

    PubMed Central

    Sharma, Vishnu Dutt; Lees, Julia; Hoffman, Nicholas E.; Brailoiu, Eugen; Madesh, Muniswamy; Wunder, Stephanie L.; Ilies, Marc A.

    2014-01-01

    The study presents the effects of blending a cationic gemini surfactant into cationic lipid bilayers and its impact towards plasmid DNA compaction and delivery process. Using nanoDSC, dynamic light scattering, zeta potential and electrophoretic mobility measurements, together with transfection (2D- and 3D-) and viability assays, we identified the main physicochemical parameters of the lipid bilayers, liposomes and lipoplexes that are affected by the gemini surfactant addition. We also correlated the cationic bilayer composition with the dynamics of the DNA compaction process, and with transfection efficiency, cytotoxicity and internalization mechanism of the resultant nucleic acid complexes. We found that blending of gemini surfactant into the cationic bilayers fluidized the supramolecular assemblies, reduced the amount of positive charge required to fully compact the plasmid DNA and, in certain cases, changed the internalization mechanism of the lipoplexes. Transfection efficiency of select ternary lipoplexes derived from cationic gemini surfactants and lipids was several times superior to transfection efficiency of corresponding binary lipoplexes, also surpassing standard transfection systems. The overall impact of gemini surfactants into the formation and dynamic of cationic bilayers was found to depend heavily on the presence of co-lipids, their nature and amount present into lipoplexes. The study confirmed the possibility of combining the specific properties of pyridinium gemini surfactants and cationic lipids synergistically for obtaining efficient synthetic transfection systems with negligible cytotoxicity useful for therapeutic gene delivery. PMID:24377350

  18. Thermal decomposition and vibrational spectroscopic aspects of pyridinium hexafluorophosphate (C5H5NHPF6)

    NASA Astrophysics Data System (ADS)

    Lekgoathi, M. D. S.; Kock, L. D.

    2016-12-01

    Thermal decomposition and vibrational spectroscopic properties of pyridinium hexafluorophosphate (C5H5NHPF6) have been studied. The structure of the compound is better interpreted as having a cubic space group, based on Raman and infrared vibrational spectroscopy experiments and group theoretical correlation data between site symmetry species and the spectroscopic space group. The 13C NMR data shows three significant signals corresponding to the three chemical environments expected on the pyridinium ring i.e. γ, β and α carbons, suggesting that the position of the anion must be symmetrical with respect to the pyridinium ring's C2v symmetry. The process of thermal decomposition of the compound using TGA methods was found to follow a contracting volume model. The activation energy associated with the thermal decomposition reaction of the compound is 108.5 kJ mol-1, while the pre exponential factor is 1.51 × 109 sec-1.

  19. Pyridinium derivatives of histamine are potent activators of cytosolic carbonic anhydrase isoforms I, II and VII.

    PubMed

    Dave, Khyati; Scozzafava, Andrea; Vullo, Daniela; Supuran, Claudiu T; Ilies, Marc A

    2011-04-21

    A series of positively-charged derivatives has been prepared by reaction of histamine with substituted pyrylium salts. These pyridinium histamine derivatives were investigated as activators of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1) and more precisely the human isoforms hCA I, II and VII. Activities from the subnanomolar to the micromolar range were detected for these compounds as activators of the three isoforms, confirming the validity of current and previous designs. The substitution pattern at the pyridinium ring was the main factor influencing activity, the three isoforms showing different structural requirements for good activity, related with the number of pyridinium substituting groups and their nature, among various alkyl, phenyl and para-substituted styryl moieties. We were successful in identifying nanomolar potent and selective activators for each isozyme and also activators with a relatively good activity against all isozymes tested--valuable lead compounds for physiology and pathology studies involving these isozymes. PMID:21369613

  20. High Proton Conductivity of Zinc Oxalate Coordination Polymers Mediated by a Hydrogen Bond with Pyridinium.

    PubMed

    Yamada, Teppei; Nankawa, Takuya

    2016-09-01

    A novel metal-organic framework, (Hpy)2[Zn2(ox)3]·nH2O (n = 0, 1), having a pyridinium cation, was newly synthesized, and the crystal structures were determined. The hydrated compound shows a high proton conductivity of 2.2 × 10(-3) S cm(-1) at 298 K and 98% relative humidity. Single crystal XRD analysis revealed a rotational displacement factor for the hydrated pyridinium ring and elongated water site that is thought to cause the high proton conductivity. PMID:27552647

  1. Structural and Formulation Factors Influencing Pyridinium Lipid-based Gene Transfer

    PubMed Central

    Zhu, Lin; Lu, Yan; Miller, Duane D.; Mahato, Ram I.

    2009-01-01

    A series of pyridinium lipids containing a heterocyclic ring and a nitrogen atom were synthesized to determine the structure-activity relationship for gene delivery. Pyrylium chloroaluminate was synthesized by monoacylation of mesityl oxide and converted into pyrylium hexafluorophosphate, which was used as the key intermediate for reaction with different primary amines, to yield hydroxyethylpyridinium hexafluorophosphate and aminoethylpyridinium hexafluorophosphate. Acylation of these pyridinium salts with different types of fatty acid chlorides afforded the final pyridinium lipids, which were mixed with a co-lipid, such as L-alpha-dioleoylphosphatidylethanolamine (DOPE) and cholesterol (Chol) to prepare cationic liposomes by sonication. These liposomes were mixed with plasmid DNA encoding enhanced green fluorescent protein (pCMS-EGFP) or luciferase (pDNA3-Luc) and transfected into Chinese Hamster Ovary (CHO) cells. Several factors including hydrophobic anchor chain length, anchor chain type, configuration of double bond, linker type, co-lipid type, cationic lipid: co-lipid molar ratio, charge ratio (N/P), and cell type had significant influence on transfection efficiency and cytotoxicity. Pyridinium lipids with amide linker showed significantly higher transfection efficiency compared to their ester counterparts. Liposomes prepared at 1:1 molar ratio of pyridinium lipid and co-lipid showed higher transfection efficiency when either DOPE or cholesterol was used as a co-lipid to prepare cationic liposomes for complex formation with plasmid DNA at 3:1(+/−) charge ratio. Pyridinium liposomes based on hydrophobic anchor chain length of 16 showed higher transfection efficiency and lower cytotoxicity. The pyridinium lipid with trans-configuration of the double bond in fatty acid chain showed higher transfection efficiency than its counterpart with cis-configuration at the same fatty acid chain length. In the presence of serum, C16:0 and Lipofectamine significantly

  2. Unexpected formation of a novel pyridinium-containing catecholate ligand and its manganese(III) complex.

    PubMed

    Sheriff, Tippu S; Watkinson, Michael; Motevalli, Majid; Lesin, Jocelyne F

    2010-01-01

    Nucleophilic aromatic substitution of tetrachloro-o-benzoquinone by pyridine and reduction of the o-quinone to the catechol by hydroxylamine forms 1,2-dihydroxy-3,5,6-trichlorobenzene-4-pyridinium chloride. This compound reacts with manganese(II) acetate in air to form chlorobis(3,5,6-trichlorobenzene 4-pyridinium catecholate)manganese(III), which represents the first complex of this ligand class to be structurally characterized by X-ray diffraction; this complex is active in the catalytic reduction of dioxygen to hydrogen peroxide under ambient conditions and turnover frequencies (TOFs) >10,000 h(-1) can be obtained. PMID:20023930

  3. Tandem dinucleophilic cyclization of cyclohexane-1,3-diones with pyridinium salts

    PubMed Central

    Kiamehr, Mostafa; Mkrtchyan, Satenik; Semeniuchenko, Volodymyr; Supe, Linda; Villinger, Alexander

    2013-01-01

    Summary The cyclization of cyclohexane-1,3-diones with various substituted pyridinium salts afforded functionalized 8-oxa-10-aza-tricyclo[7.3.1.02,7]trideca-2(7),11-dienes. The reaction proceeds by regioselective attack of the central carbon atom of the 1,3-dicarbonyl unit to 4-position of the pyridinium salt and subsequent cyclization by base-assisted proton migration and nucleophilic addition of the oxygen atom to the 2-position, as was elucidated by DFT computations. Fairly extensive screening of bases and additives revealed that the presence of potassium cations is essential for formation of the product. PMID:23843903

  4. [pi]-Stacking and aggregation of pyridinium-substituted indolizines

    SciTech Connect

    Carter, P.W.; DiMagno, S.G. ); Porter, J.D.; Streitwieser, A. )

    1993-02-04

    The tendency for pyridinium-substituted indolizines to aggregate in aqueous and acetonitrile solution is dominated by solute-solvent interactions and by the amphiphilic nature of the cations. In solution, these compounds exhibit an unusual sequence of discrete, red-shifted fluorescence bands whose intensities are a function of concentration over the range 10[sup [minus]5]--10[sup [minus]3] M. It is proposed that [pi]-stacking of the indolizine residues results in weak electronic interactions ([beta] [approximately]0.13 eV) which are sufficient to result in the delocalization of bound excitonic states over the aggregate. Fluorescence from the aggregate occurs by radiative annihilation of the delocalized exciton. Stepwise dimerization (K[sub 2]) and trimerization (K[sub 3]) equilibrium constants for the cations calculated from the emission spectra range from about 400 to 65,000. Solution conductivity measurements indicate that cation aggregation does not require ion pairing. However, where significant ion-pairing does occur, K[sub 2] and K[sub 3] are increased by at least an order of magnitude. X-ray crystallography was used to determine the structures of cation dimers which form in the solid state, and these structures were used as working models for the geometry of the solution aggregates. Electrostatic and dispersion interactions calculated on the basis of those geometries account for some of the free energy of aggregate formation, but solvent entropic effects are believed to provide the strongest driving force for indolizine aggregation in solution. 58 refs., 8 figs., 4 tabs.

  5. Crystal structure and thermal behaviour of pyridinium styphnate

    PubMed Central

    Muthulakshmi, Selvarasu; Kalaivani, Doraisamyraja

    2015-01-01

    In the crystal structure of the title mol­ecular salt, C5H6N+·C6H2N3O8 − (systematic name: pyridinium 3-hy­droxy-2,4,6-tri­nitro­phenolate), the pyridin­ium cation and the 3-hy­droxy-2,4,6-tri­nitro­phenolate anion are linked through bifurcated N—H⋯(O,O) hydrogen bonds, forming an R 1 2(6) ring motif. The nitro group para with respect to phenolate ion forms an intra­molecular hydrogen bond with the adjacent phenolic –OH group, which results in an S(6) ring motif. The nitro group flanked by the phenolate ion and the phenolic –OH group deviates noticeably from the benzene ring, subtending a dihedral angle of 89.2 (4)°. The other two nitro groups deviate only slightly from the plane of the benzene ring, making dihedral angles of 2.8 (4) and 3.4 (3)°. In the crystal, the 3-hy­droxy-2,4,6-tri­nitro­phenolate anions are linked through O—H⋯O hydrogen bonds, forming chains along [100]. These anionic chains, to which the cations are attached, are linked via C—H⋯O hydrogen bonds, forming a three-dimensional structure. Impact friction sensitivity tests and TGA/DTA studies on the title mol­ecular salt imply that it is an insensitive high-energy-density material. PMID:25878796

  6. Neurological manifestation of methyl bromide intoxication.

    PubMed

    Suwanlaong, Kanokrat; Phanthumchinda, Kammant

    2008-03-01

    Methyl bromide is a highly toxic gas with poor olfactory warning properties. It is widely used as insecticidal fumigant for dry foodstuffs and can be toxic to central and peripheral nervous systems. Most neurological manifestations of methyl bromide intoxication occur from inhalation. Acute toxicity characterized by headache, dizziness, abdominal pain, nausea, vomiting and visual disturbances. Tremor, convulsion, unconsciousness and permanent brain damage may occur in severe poisoning. Chronic exposure can cause neuropathy, pyramidal and cerebellar dysfunction, as well as neuropsychiatric disturbances. The first case of methyl bromide intoxication in Thailand has been described. The patient was a 24-year-old man who worked in a warehouse of imported vegetables fumigated with methyl bromide. He presented with unstable gait, vertigo and paresthesia of both feet, for two weeks. He had a history of chronic exposure to methyl bromide for three years. His fourteen co-workers also developed the same symptoms but less in severity. Neurological examination revealed ataxic gait, decreased pain and vibratory sense on both feet, impaired cerebellar signs and hyperactive reflex in all extremities. The serum concentration of methyl bromide was 8.18 mg/dl. Electrophysilogical study was normal. Magnetic resonance imaging of the brain (MRI) revealed bilateral symmetrical lesion of abnormal hypersignal intensity on T2 and fluid-attenuation inversion recovery (FLAIR) sequences at bilateral dentate nuclei of cerebellum and periventricular area of the fourth ventricle. This incident stresses the need for improvement of worker education and safety precautions during all stages of methyl bromide fumigation. PMID:18575299

  7. Potassium bromide method of infrared sampling

    USGS Publications Warehouse

    Milkey, R.G.

    1958-01-01

    In the preparation of potassium bromide pressed windows for use in the infrared analysis of solids, severe grinding of the potassium bromide powder may produce strong absorption bands that could interfere seriously with the spectra of the sample. These absorption bands appear to be due to some crystal alteration of the potassium bromide as a result of the grinding process. They were less apt to occur when the coarser powder, which had received a relatively gentle grinding, was used. Window blanks prepared from the coarser powders showed smaller adsorbed water peaks and generally higher over-all transmittance readings than windows pressed from the very fine powders.

  8. 2-Alkynyl-N-propargyl pyridinium salts: pyridinium-based heterocyclic skipped aza-enediynes that cleave DNA by deoxyribosyl hydrogen-atom abstraction and guanine oxidation.

    PubMed

    Tuesuwan, Bodin; Kerwin, Sean M

    2006-06-13

    Diradical-generating cyclizations such as the enediyne Bergman cyclization and the enyne allene Myers-Saito cyclization have been exploited by nature in the mechanism of DNA cleavage by a series of potent antitumor antibiotics. Alternative diradical-generating cyclizations have been proposed in the design of selective antitumor agents; however, little information is available concerning the utility of these alternative cyclizations in radical-based DNA cleavage chemistry. One such alternative diradical-generating cyclization, the aza-Myers-Saito cyclization of aza-enyne allenes that are derived from base-promoted isomerization of skipped aza-enediynes, has been recently reported. Here, we report the synthesis and DNA cleavage chemistry of a series of pyridinium skipped aza-enediynes (2-alkynyl-N-propargyl pyridinium salts). Efficient DNA cleavage requires the presence of the skipped aza-enediyne functionality, and optimal DNA cleavage occurs at basic pH. Within this series of compounds, the analogue bearing a p-methoxyphenyl group on the pyridinium 2-alkyne substituents was found to be the most effective DNA cleavage agent, displaying significant supercoiled DNA-nicking activity at concentrations as low as 1 microM. Detailed studies of this analogue show that DNA cleavage occurs through 4'-hydrogen-atom abstraction from the DNA backbone and oxidation of guanine bases. This is the first report of enediyne-like radical-based DNA cleavage by an agent designed to undergo an alternative diradical-generating cyclization. PMID:16752915

  9. Emission of methyl bromide from biomass burning

    SciTech Connect

    Manoe, S.; Andreae, M.O. )

    1994-03-04

    Bromine is, per atom, far more efficient than chlorine in destroying stratospheric ozone, and methyl bromide is the single largest source of stratospheric bromine. The two main previously known sources of this compound are emissions from the ocean and from the compound's use as an agricultural pesticide. Laboratory biomass combustion experiments showed that methyl bromide was emitted in the smoke from various fuels tested. Methyl bromide was also found in smoke plumes from wildfires in savannas, chaparral, and boreal forest. Global emissions of methyl bromide from biomass burning are estimated to be in the range of 10 to 50 gigagrams per year, which is comparable to the amount produced by ocean emission and pesticide use and represents a major contribution ([approximately]30 percent) to the stratospheric bromine budget.

  10. Growth and characterization of lead bromide crystals

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Gottlieb, M.; Henningsen, T.; Hopkins, R. H.; Mazelsky, R.; Glicksman, M. E.; Coriell, S. R.; Santoro, G. J.; Duval, W. M. B.

    1992-01-01

    Lead(II) bromide was purified by a combination of directional freezing and zone-refining methods. Differential thermal analysis of the lead bromide showed that a destructive phase transformation occurs below the melting temperature. This transformation causes extensive cracking, making it very difficult to grow a large single crystal. Energy of phase transformation for pure lead bromide was determined to be 24.67 cal/g. To circumvent this limitation, crystals were doped by silver bromide which decreased the energy of phase transformation. The addition of silver helped in achieving the size, but enhanced the inhomogeneity in the crystal. The acoustic attenuation constant was almost identical for the pure and doped (below 3000 ppm) crystals.

  11. A Facile Oxidation of Alcohols Using Pyridinium Chlorochromate/Silica Gel

    NASA Astrophysics Data System (ADS)

    Luzzio, Frederick A.; Fitch, Richard W.; Moore, William J.; Mudd, Kelli J.

    1999-07-01

    An efficient and convenient adaptation of the pyridinium chlorochromate (PCC) oxidation for an organic chemistry student exercise is based on the employment of reagent-grade silica gel, which simplifies workup and purification of the product. The procedures include the oxidation of 4-tert-butylcyclohexanol to 4-tert-butylcyclohexanone and d,l-menthol to d,l-menthone.

  12. Aryl-triazole foldamers incorporating a pyridinium motif for halide anion binding in aqueous media.

    PubMed

    Shang, Jie; Zhao, Wei; Li, Xichen; Wang, Ying; Jiang, Hua

    2016-03-15

    Aryl-triazole oligomers incorporating a pyridinium motif have been synthesized from their pyridine precursors. Anion binding studies show that methylation of the pyridine units can significantly enhance the halide anion affinities of the folded oligomers so that the foldamers are capable of binding halide anions in aqueous solutions. PMID:26933696

  13. Pyridinium hydrobromide perbromide: a versatile catalyst for aziridination of olefins using Chloramine-T.

    PubMed

    Ali, S I; Nikalje, M D; Sudalai, A

    1999-09-01

    [reaction: see text] Pyridinium hydrobromide perbromide (Py x HBr3) catalyzes effectively the aziridination of electron-deficient as well as electron-rich olefins using Chloramine-T (N-chloro-N-sodio-p-toluenesulfonamide) as a nitrogen source to afford the corresponding aziridines in moderate to good yields. PMID:16118868

  14. Investigation of drug interactions with pinaverium bromide.

    PubMed

    Devred, C; Godeau, P; Guerot, C; Librez, P; Mougeot, G; Orsetti, A; Segrestaa, J M

    1986-01-01

    A series of studies was carried out at 6 centres to investigate possible drug interaction between the spasmolytic, pinaverium bromide, and cardiac glycosides, anticoagulants and hypoglycaemic agents given to patients as part of the long-term treatment of their condition. The results of clinical and laboratory investigations did not show any evidence of pinaverium bromide interfering with the action or activity of any of the drugs studied. PMID:3084176

  15. Chiral Pyridinium Phosphoramide as a Dual Brønsted Acid Catalyst for Enantioselective Diels-Alder Reaction.

    PubMed

    Nishikawa, Yasuhiro; Nakano, Saki; Tahira, Yuu; Terazawa, Kanako; Yamazaki, Ken; Kitamura, Chitoshi; Hara, Osamu

    2016-05-01

    Chiral pyridinium phosphoramide 1·HX was designed to be a new class of chiral Brønsted acid catalyst in which both the pyridinium proton and the adjacent imide-like proton activated by the electron-withdrawing pyridinium moiety could work cooperatively as strong dual proton donors. The potential of 1·HX was shown in the enantioselective Diels-Alder reactions of 1-amino dienes with various dienophiles including N-unsubstituted maleimide, which has yet to be successfully used in an asymmetric Diels-Alder reaction. PMID:27093584

  16. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must...

  17. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must...

  18. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must...

  19. Analysis of mixed micellar and interfacial behavior of cationic gemini hexanediyl-1,6-bis(dimethylcetylammonium bromide) with conventional ionic and nonionic surfactants in aqueous medium.

    PubMed

    Din, Kabir-ud; Sheikh, Mohmad Shafi; Dar, Aijaz Ahmad

    2010-05-13

    The interaction between cationic gemini hexanediyl-1,6-bis(dimethylcetylammonium bromide) (16-6-16, abbreviated as G6) with conventional cationic cetylpyridinium chloride (CPC), anionic sodium bis(2-ethyl hexyl)sulfosuccinate (AOT) and nonionic polyoxyethylene 10 cetyl ether (Brij56) in aqueous medium has been investigated at 25 degrees C. Different physicochemical properties such as critical micelle concentration (cmc), surface excess concentration (Gamma(max)), minimum area per molecule (A(min)), and interaction parameters (beta(m), beta(sigma)) as well as other thermodynamic and micellar properties have been determined. The interfacial and bulk behaviors were explored using theoretical models of Clint, Rubingh, Rosen, Motomura, and Maeda for justification and comparison of results of different binary combinations with the geminis of alkanediyl-alpha,omega-bis(dimethylcetylammonium bromide) series. Synergism was observed in all the binary combinations in the micelle and at interface with lowering of packing parameter due to slight expansion of A(min). The results of the present study could be of interest for selection of surfactant mixtures for surfactant-enhanced remediation (SER) of soils and aquifers contaminated by hydrophobic organic compounds (HOCs). PMID:20397638

  20. [The clinical pharmacological profile of pinaverium bromide].

    PubMed

    Guslandi, M

    1994-04-01

    Pinaverium bromide is a locally acting spasmolytic agent of the digestive tract. Its mechanism of action relies upon inhibition of calcium ion entrance into smooth muscle cells (calcium-antagonist effect). In humans pinaverium facilitates gastric emptying and decreases intestinal transit time in patients with constipation. Pinaverium is very effective in improving symptoms of irritable bowel syndrome (abdominal pain, gas, diarrhea or constipation). In this respect the drug proved to be significantly superior to placebo, at least as effective as trimebutine and on the whole more active than otilonium and prifinium bromide, being always extremely well tolerated. PMID:8028745

  1. Effects of pinaverium bromide on Oddi's sphincter.

    PubMed

    DiSomma, C; Reboa, G; Patrone, M G; Mortola, G P; Sala, G; Ciampini, M

    1986-01-01

    Twelve to 15 days after cholecystectomy, endocholedochal pressure was measured in ten patients before and one hour after oral administration of 15 mg of pinaverium bromide (six patients) or placebo. The mean endocholedochal pressure was 7.1 +/- 0.25 mmHg before and 3.1 +/- 0.2 mmHg after pinaverium (P less than 0.01), and 7.0 +/- 0.2 and 6.8 +/- 1.2 mmHg in the placebo-treated patients. The results suggest that pinaverium bromide has a specific effect on the common bile duct and probably on Oddi's sphincter. PMID:3815457

  2. On the viscosity of pyridinium based ionic liquids: an experimental and computational study.

    PubMed

    Bandrés, Isabel; Alcalde, Rafael; Lafuente, Carlos; Atilhan, Mert; Aparicio, Santiago

    2011-11-01

    A study on the viscosity of eight pyridinium based ionic liquids is reported for wide pressure and temperature ranges. Measurements were performed using an electromagnetic moving piston viscometer. Experimental data were fitted to a Tait-like equation demonstrating good correlations, which was used to calculate pressure/viscosity and temperature/viscosity coefficients. The effect of the involved anions and cation on the ionic liquid viscosity was analyzed from a molecular viewpoint using hole theory, quantum chemistry calculations using density functional theory, and classical molecular dynamics simulations. The analysis of the experimental and computational results shows the complex effects controlling viscosity of studied fluids, including strength of ionic pairs, molecular sizes, and mobility and effects rising from the availability and cavity sizes distributions in pyridinium-based ionic liquids. PMID:21942824

  3. Oxygen versus nitrogen interactions in lithium dinitramidate dihydrate and pyridinium dinitramidate.

    PubMed

    Klapötke, Thomas M; Krumm, Burkhard; Scherr, Matthias

    2008-01-01

    The title compounds, diaquadinitramidatolithium(I), [Li(N3O4)(H2O)2], (I), and pyridinium dinitramidate, C5H6N+ x N3O4(-), (II), differ significantly in their cation-anion contacts. The Li+ atom of (I) is coordinated by two O atoms of the dinitramide anion in a chelate and by four additional water molecules, with the Li and central N atom of the anion on a twofold rotation axis. The pyridinium cation of (II) exhibits a contact with the dinitramide anion via an intermolecular N-H...N hydrogen bridge. These interactions are compared with those found in reported anhydrous lithium dinitramide and ammonium dinitramide salts. PMID:18216429

  4. Regioselective nucleophilic addition of organometallic reagents to 3-geminal bis(silyl) N-acyl pyridinium.

    PubMed

    Wu, Ya; Li, Linjie; Li, Hongze; Gao, Lu; Xie, Hengmu; Zhang, Zhigao; Su, Zhishan; Hu, Changwei; Song, Zhenlei

    2014-04-01

    A regioselective nucleophilic addition to 3-geminal bis(silyl) N-acyl pyridinium has been described. Geminal bis(silane) shows contrasting roles that lead to different regioselectivities for the addition of different nucleophiles: its steric effect dominates to favor 1,6-addition of alkyl, vinyl, and aryl organometallic reagents; its directing effect dominates to favor 1,2-addition of less sterically demanding alkynyl Grignard reagents. PMID:24666415

  5. Molecular-structural aspects of formation of spectral-luminescent properties of the arylsubstituted pyridinium cations

    SciTech Connect

    Tymyansky, Ya.P.; Knyazhansky, M.I.; Feigelman, V.M.; Kharlanov, V.A.

    1985-04-01

    Using the structure modelling method, the nature of different bands in the absorption spectra of arylsubstituted pyridinium cations has been ascertained. The nature and localization of radiative transitions from singlet and triplet states have been determined. The anomalous Stokes fluorescence shift at room temperature has been explained by adiabatic twist of 2,6-aryl substituents around C-C bond in an excited state. The general scheme of the excited state energy deactivation photophysical processes at 293 and 77 K is presented.

  6. Electronic structure and spectral-luminescent properties of 1,2,4,6-tetrasubstituted pyridinium salts

    SciTech Connect

    Korunova, A.F.; Krainov, I.P.; Protsenko, E.G.

    1985-09-01

    The structure of the electronic excitation of 1,2,4,6-tetrasubstituted pyridinium salts was studied by quantum-chemical calculations carried out by the SCF PPP CI method, using excitation-localization numbers on the atoms and fragments, and interfragmentary charge transfer numbers. The nature of the absorption bands observed in the spectra and certain structural factors causing the spectral-luminescent properties were established.

  7. Kinetics of the reduction of pyridinium ions by 2-hydroxy-2-propyl radicals in aqueous solution

    SciTech Connect

    Shimura, M.; Espenson, J.H.

    1983-01-19

    Kinetic measurements were made for the reductions of the pyridinium ions derived from pyridine, 4-methylpyridine, 3-hydroxypyridine, nicotinamide, and isonicotinamide as well as 1-methylpyridinium and 1,4-dimethylpyridinium ions by 2-hydroxy-2-propyl radicals, which were generated by the homolytic cleavage of the chromium-carbon bond in (H/sub 2/O)/sub 5/CrC(CH/sub 3/)/sub 2/OH/sup 2 +/. The rate constants (dm/sup 3/ mol/sup -1/ s/sup -1/) at 25.0/sup 0/C and an ionic strength of 1.0M (LiClO/sub 4/) are as follows: pyridinium ion, 9.6 x 10/sup 5/; 1-methylpyridinium ion, 3.7 x 10/sup 5/; 4-methylpyridinium ion, 7.3 x 10/sup 4/; 1,4-dimethylpyridinium ion, less than or equal to1 x 10/sup 4/; 3-hydroxypyridinium ion, 1.4 x 10/sup 8/; 3-(aminocarbonyl)pyridinium ion, 7.9 x 10/sup 8/; 4-(aminocarbonyl)pyridinium ion, 1.2 x 10/sup 9/. The rate constants are reasonably well correlated by the Hammett p-sigma equation with p = +8.5. The first two compounds show a second kinetic term corresponding to the rate law k'(Cr/sup 2 +/)(pyH/sup +/)(.C-(CH/sub 3/)/sub 2/OH)(H/sup +/)/sup -1/, consistent with reduction of a Cr(II)-pyridine complex by the free radical.

  8. Stereoselective Synthesis of Tetrahydroindolizines through the Catalytic Formation of Pyridinium Ylides from Diazo Compounds.

    PubMed

    Day, Jonathan; McKeever-Abbas, Ben; Dowden, James

    2016-05-01

    Commercially available iron(III) and copper(I) complexes catalyzed multicomponent cycloaddition reactions between diazo compounds, pyridines, and electrophilic alkenes to give alkaloid-inspired tetrahydroindolizidines in high yield with high diastereoselectivity. Hitherto, the catalytic formation of versatile pyridinium ylides from metal carbenes has been poorly developed; the broad utility demonstrated herein sets the stage for the invention of further multicomponent reactions in future. PMID:27059910

  9. Antithrombotic effects of pyridinium compounds formed from trigonelline upon coffee roasting.

    PubMed

    Kalaska, Bartlomiej; Piotrowski, Lukasz; Leszczynska, Agnieszka; Michalowski, Bartosz; Kramkowski, Karol; Kaminski, Tomasz; Adamus, Jan; Marcinek, Andrzej; Gebicki, Jerzy; Mogielnicki, Andrzej; Buczko, Wlodzimierz

    2014-04-01

    Coffee may exert a preventive effect on arterial thrombosis. Trigonelline is one of the most abundant compounds in coffee that undergoes pyrolysis upon roasting of coffee beans. The aim of the present study was to identify pyridinium compounds formed upon trigonelline pyrolysis and coffee roasting and to investigate the effect of three of them, i.e., 1-methylpyridine and 1,3- and 1,4-dimethylpyridine, on experimentally induced arterial thrombosis in rats. 1,3- and 1,4-dimethylpyridine but not 1-methylpyridine inhibited arterial thrombus formation. 1,3-Dimethylpyridine inhibited platelet aggregation and reduced fibrin formation in platelet-rich plasma, whereas 1,4-dimethylpyridine increased the plasma level of 6-keto-PGF1α. 1,4-Dimethylpyridine slightly increased rat tissue plasminogen activator plasma activity. In summary, we demonstrated that pyridinium compounds display mild antithrombotic properties due to stimulation by prostacyclin release (1,4-dimethylpyridine) and inhibition of platelet aggregation (1,3-dimethylpyridine). Those pyridinium compounds may, to some extent, be responsible for the beneficial effects of coffee drinking. PMID:24650005

  10. Crystal structure of 2,6-di­amino­pyridinium chloride

    PubMed Central

    Mastalir, Matthias; Schroffenegger, Martina; Stöger, Berthold; Weil, Matthias; Kirchner, Karl

    2016-01-01

    The asymmetric unit of the title salt, C5H8N3 +·Cl−, comprises one half of the 2,6-di­amino­pyridinium cation (the other half being completed by the application of mirror symmetry) and one Cl− counter-anion, also located on the mirror plane. The amino N atom shows a significant pyramidalization, with a dihedral angle of 30.4 (14)° between the least-squares planes of the amino group and the non-H atoms of the 2,6-di­amino­pyridinium moiety. In the crystal, the cationic mol­ecules and Cl− counter-anions are arranged in sheets parallel to (001) consisting of alternating polar and non-polar parts associated with the the Cl− anions, pyridinium and amino moieties, and the pyridine rings, respectively. N—H⋯Cl inter­actions within the polar part, as well as slipped π–π inter­actions in the non-polar part, help to establish the three-dimensional network. PMID:27006800

  11. Crystal structure of 2,6-di-amino-pyridinium chloride.

    PubMed

    Mastalir, Matthias; Schroffenegger, Martina; Stöger, Berthold; Weil, Matthias; Kirchner, Karl

    2016-03-01

    The asymmetric unit of the title salt, C5H8N3 (+)·Cl(-), comprises one half of the 2,6-di-amino-pyridinium cation (the other half being completed by the application of mirror symmetry) and one Cl(-) counter-anion, also located on the mirror plane. The amino N atom shows a significant pyramidalization, with a dihedral angle of 30.4 (14)° between the least-squares planes of the amino group and the non-H atoms of the 2,6-di-amino-pyridinium moiety. In the crystal, the cationic mol-ecules and Cl(-) counter-anions are arranged in sheets parallel to (001) consisting of alternating polar and non-polar parts associated with the the Cl(-) anions, pyridinium and amino moieties, and the pyridine rings, respectively. N-H⋯Cl inter-actions within the polar part, as well as slipped π-π inter-actions in the non-polar part, help to establish the three-dimensional network. PMID:27006800

  12. Methyl Bromide Alternatives for Vineyard Replant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The project is part of the USDA-ARS Pacific Area-Wide Pest Management Program for Methyl Bromide Alternatives. This is the first year of a three-year project. The research was initiated in summer 2007 with a field study planned for October 2007 at the USDA-ARS San Joaquin Valley Agricultural Scienc...

  13. METHYL BROMIDE ALTERNATIVES FOR CALIFORNIA STRAWBERRY NURSERIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of methyl bromide (MB) alternative fumigants on soil pests, plant productivity in nursery and fruiting fields, as well as production costs, were evaluated in California strawberry nurseries by an interdisciplinary team. Our trials followed nursery stock through low and high elevation ph...

  14. Zinc Bromide Waste Solution Treatment Options

    SciTech Connect

    Langston, C.A.

    2001-01-16

    The objective of this effort was to identify treatment options for 20,000 gallons of low-level radioactively contaminated zinc bromide solution currently stored in C-Area. These options will be relevant when the solutions are declared waste.

  15. Challenges in Weed Management Without Methyl Bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide has been used for several decades for pre-plant soil fumigation in high value agricultural and horticultural crops because it can provide broad-spectrum control of insects, nematodes, pathogens, and weeds. However, MeBr has been identified as a powerful ozone-depleting chemical and i...

  16. Methyl bromide emissions from tarped fields

    SciTech Connect

    Cicerone, R.J.; Williams, J.; Wang, N.Y.

    1995-12-31

    Once in the stratosphere, bromine atoms can destroy ozone effectively. Because of this potential effect, certain organobromine compounds including methyl bromide (MeBr) are being controlled or eliminated by national and international regulations. It would be valuable to determine the fraction of MeBr used in soil fumigations that subsequently enters the atmosphere to better assess the need for, and value of, strong regulations. We have designed and conducted several experiments accompanying field fumigations with MeBr/chloropicrin mixtures. In each of three field-fumigation experiments new Irvine, CA in which the fumigated field was covered immediately with plastic tarping, we have deployed static flux chambers on top of the tarping and measured escape fluxes of MeBr. After tarp removal, the same chambers were replaced on the bare soil to continue the measurements. We have also measured soil bromide contents before and after the fumigation. One experiment yielded an escape fraction of 80 to 87% (with 19% remaining as bromide) while the other two experiments yielded escape fractions of 30 to 35% (with about 70% remaining as bromide). This paper will summarize stratospheric bromine chemistry, describe the field experiments and discuss factors that influence emissions, including soil pH, moisture and organic content and injection technique. We acknowledge TriCal, Inc. for many helpful discussions and for professional field applications of MeBr.

  17. Can Georgia growers replace methyl bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The price and availability of methyl bromide is limiting its use on Georgia farms; the need for an alternative is essential for sustainable vegetable production in GA. Three alternatives were evaluated in on-farm trials in the spring 2007 in Tift, Colquitt and Echols Counties. Treatments were replic...

  18. Torque vs. induced load of A-286, and MP35N nuts and bolts with cadmium, dry film, and cetyl alcohol lubricants

    NASA Technical Reports Server (NTRS)

    Crispell, C.

    1978-01-01

    Data for specific joint design, utilizing various combinations of bolt, nut and lubricants in typical structure of the shuttle booster rocket is obtained. Requirements of the structure performance criteria were to withstand temperatures of 260 C (500 F) and to provide a nut lubricant which would be compatible with sealants used in the joint. Cadmium plating and dry film lubricant meeting the requirements of MIL-L-8937 were the lubricants specified. In a follow up effort, cadmium plating and cetyl alcohol were further specified The materials for the bolt and nut combinations were MP35N and A-286. These materials demand a lubricant to be used to prevent galling of the thread when tightened and also to help reduce the scatter of clamping load in application.

  19. A comparison of the action of otilonium bromide and pinaverium bromide: study conducted under clinical control.

    PubMed

    Defrance, P; Casini, A

    1991-11-01

    We studied 40 patients with irritable bowel syndrome (IBS) which received in a simple-blind fashion otilonium and pinaverium bromide (15 days each drug). During each 15-day period we evaluated: number of pain episodes, intensity of pain, number of bowel movements, side effects. Otilonium bromide, (OB), compared with pinaverium bromide was able to significantly (p less than 0.05) reduce the number of pain attacks, whereas no significant differences were found between the 2 groups as regards the other parameters. The occurrence of side effects was similar in the two treatment courses. We can conclude that the two types of treatment were similarly useful in IBS, although OB seems more effective than pinaverium bromide. PMID:1756286

  20. EVALUATION OF PROPARGYL BROMIDE AS A SOIL FUMIGANT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cut flower and bulb industry has relied heavily upon the use of methyl bromide as a key soil treatment for soilborne pest control. Due to the phase-out of methyl bromide it is important to develop alternatives to manage pests now managed by methyl bromide. The emphasis of this work was to eval...

  1. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  2. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  3. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  4. 21 CFR 522.275 - N-Butylscopolammonium bromide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this...

  5. WEED CONTROL IN THE LIFE AFTER METHYL BROMIDE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetable growers are losing the soil fumigant methyl bromide. Efforts are on-going to extend the deadline for using methyl bromide until suitable alternatives are developed. Regardless of whether the deadline is extended or not, growers need to begin to study alternatives to methyl bromide and be...

  6. 75 FR 5582 - Methyl Bromide; Amendments to Terminate Uses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-03

    ... AGENCY Methyl Bromide; Amendments to Terminate Uses AGENCY: Environmental Protection Agency (EPA). ACTION... requested by the registrants and accepted by the Agency, of products containing the pesticide methyl bromide... Requests from the registrants listed in Table 2 to amend to terminate post-harvest methyl bromide uses...

  7. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Methyl bromide; tolerances for... § 180.124 Methyl bromide; tolerances for residues. (a) General. A tolerance is established for residues of the fumigant methyl bromide, including metabolites and degradates, in or on the commodity in...

  8. 7 CFR 305.6 - Methyl bromide fumigation treatment schedules.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Methyl bromide fumigation treatment schedules. 305.6..., fumigation with methyl bromide for sapote fruit fly. Regulated citrus fruits originating inside an area... equal concentrations of methyl bromide throughout the chamber, a fan should be placed near the point...

  9. A one-dimensional CdII coordination polymer constructed from 4-(dimethylamino)pyridinium-1-acetate ligands and thiocyanate coordination bridges.

    PubMed

    Wang, Hui-Ting; Zhou, Lin

    2015-07-01

    A new cadmium-thiocyanate complex, namely catena-poly[1-carboxymethyl-4-(dimethylamino)pyridinium [cadmium(II)-tri-μ-thiocyanato-κ(4)N:S;κ(2)S:N] [[[4-(dimethylamino)pyridinium-1-acetate-κ(2)O,O']cadmium(II)]-di-μ-thiocyanato-κ(2)N:S;κ(2)S:N

  10. Measurements of atmospheric methyl bromide and bromoform

    SciTech Connect

    Cicerone, R.J.; Heidt, L.E.; Pollock, W.H.

    1988-04-20

    We have measured gaseous methyl bromide (CH/sub 3/Br) and bromoform (CHBr/sub 3/) in air samples that were gathered approximately weekly from five ground-level sites: Point Barrow, Alaska; Mauna Loa Observatory and Cape Kumukahi, Hawaii; Matatula, Samoa; and Kaitorete Spit, New Zealand. Approximately 750 samples have been analyzed for CH/sub 3/Br between January 1985 and October 1987 and 990 samples have been analyzed for CHBr/sub 3/ between early 1984 and September 1987, all by gas chromatography/mass spectroscopy. Methyl bromide concentrations are typically 10--11 parts per trillion (ppt) by volume; there are no clear indications of temporal increases. Bromoform concentrations are typically 2--3 ppt, but large seasonal variations are seen at Point Barrow. copyright American Geophysical Union 1988

  11. Removal of bromide and natural organic matter by anion exchange.

    PubMed

    Hsu, Susan; Singer, Philip C

    2010-04-01

    Bromide removal by anion exchange was explored for various water qualities, process configurations, and resin characteristics. Simulated natural waters containing different amounts of natural organic matter (NOM), bicarbonate, chloride, and bromide were treated with a polyacrylate-based magnetic ion exchange (MIEX) resin on a batch basis to evaluate the effectiveness of the resin for removal of bromide. While bromide removal was achieved to some degree, alkalinity (bicarbonate), dissolved organic carbon (DOC), and chloride were shown to inhibit bromide removal in waters with bromide concentrations of 100 and 300 microg/L. Water was also treated using a two-stage batch MIEX process. Two-stage treatment resulted in only a slight improvement in bromide removal compared to single-stage treatment, presumably due to competition with the high concentration of chloride which is present along with bromide in natural waters. In view of the relatively poor bromide removal results for the MIEX resin, a limited set of experiments was performed using polystyrene resins. DOC and bromide removal were compared by treating model waters with MIEX and two polystyrene resins, Ionac A-641 and Amberlite IRA910. The two polystyrene resins were seen to be more effective for bromide removal, while the MIEX resin was more effective at removing DOC. PMID:20045170

  12. [Research advances in methyl bromide in the ocean].

    PubMed

    Du, Hui-na; Xie, Wen-xia; Cui, Yu-qian; Chen, Jian-lei; Ye, Si-yuan

    2014-12-01

    Methyl bromide is an important atmospheric trace gas, which plays significant roles in the global warming and atmospheric chemistry. The ocean plays important and complex roles in the global biogeochemical cycles of methyl bromide, not only the source of atmospheric methyl bromide, but also the sink. Therefore, developing the chemical research of the soluble methyl bromide in the ocean, will not only have a certain guiding significance to the atmospheric ozone layer protection, but also provide a theoretical basis for estimating methyl bromide's contribution to the global environmental change on global scale. This paper reviewed the research advances on methyl bromide in the ocean, from the aspects of the biogeochemical cycle of methyl bromide in the ocean, the analysis and determination method, the concentration distribution, the sea-to-air flux and its sources and sinks in the atmosphere. Some deficiencies in the current studies were put forward, and the directions of the future studies were prospected. PMID:25876424

  13. Methyl bromide: Ocean sources, ocean sinks, and climate sensitivity

    SciTech Connect

    Anbar, A.D.; Yung, Y.L.; Chavez, F.P.

    1996-03-01

    This study was performed to examine conflicting conclusions of two previously published studies which estimated the size of oceanic sources of methyl bromide. In addition, the sensitivity of atmospheric methyl bromide to climatic variations was examined. A steady state mass balance model was used to reexamine data from the previous studies. Linear scaling of methyl bromide production rates to chlorophyll content provided agreement between the two models. The results suggest that the open ocean is a small net sink for atmospheric methyl bromide, rather than a large net source. A high rate of biological production of methyl bromide in seawater is also strongly indicated. A coupled ocean-atmosphere model indicated that methyl bromide variations induced by climatic change can be larger than those resulting from 25% variations in anthropogenic sources. Quantifying marine production rates of methyl bromide is suggested as a necessary step in assessing stratospheric ozone loss. 63 refs., 10 figs., 2 tabs.

  14. Lattice vibrations in lead bromide and chloride

    NASA Astrophysics Data System (ADS)

    Carabatos-Nédelec, C.; Bréhat, F.; Wyncke, B.

    Lead bromide and lead chloride lattice dynamics studies by polarized IR reflectivity and Raman scattering are reported at room temperature and at 10 K. Reflectivity spectra from 20 to 300 cm -1 have been fitted with a model of the factorized form of the dielectric function. The lattice modes frequencies, damping factors and oscillators strengths are given, as well as the effective charges of the polar modes. The study concludes the ionic character of the compounds.

  15. Methyl bromide users search for science

    SciTech Connect

    Winegar, E.D.

    1995-01-01

    Workers, neighbors and the ozone are protected by regulation from this chemical, but those needing it complain that a solid foundation is lacking for the rules. Although not yet featured on {open_quotes}60 Minutes,{close_quotes} the pesticide methyl bromide is gaining widespread attention because of its central position in debates about worker health and safety, environmental toxics exposure and global ozone depletion.

  16. Methyl bromide volatility measurements from treated fields

    SciTech Connect

    Majewski, M.S.; Woodrow, J.E.; Seiber, J.N. |

    1995-12-31

    Methyl bromide is used as an agricultural soil fumigant and concern is growing over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and little is known about how much of the applied fumigant volatilizes into the atmosphere after application. The post-application volatilization losses of methyl bromide from two fields using different application practices were measured using an aerodynamic-gradient technique. One field was covered with a high-barrier plastic film tarp during application and the other was left uncovered, but the furrows made by the injection shanks were bedded over. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 days of the experiment and about 32% of the nominal application within 9 days including the one day after the tarp was removed on day 8. The nontarped field lost 89%of the nominal application by volatilization in 5 days. The error associated, with each flux measurement, as well as variations in daily flux losses with differing sampling period lengths show the degree of variability inherent in this type of study.

  17. Methyl bromide fate in fumigated soils

    SciTech Connect

    Anderson, T.A.; Rice, P.J.; Cink, J.H.

    1995-12-31

    Although widespread use of methyl bromide (MeBr) as a sail and structure fumigant has previously been recognized as a potential significant source of atmospheric MeBr, losses have not been well quantified. Our research indicates that, in laboratory studies, MeBr is volatilized rapidly from fumigated soils and that volatility increases with temperature (35{degrees}C > 25{degrees}C and 15{degrees}C) and moisture (0.03 bar and 0.3 bar > 1 bar > 3 bar). Degradation of MeBr in soil, as indicated by production of bromide ion, was also directly related to temperature and moisture. Most of the soil degradation of MeBr in these studies appears to be abiotic based on the observation of toxicity (reduced microbial respiration) in fumigated soils. We also determined the transformation and movement of MeBr in undisturbed soil columns. These studies also indicated that MeBT volatilizes rapidly (> 50% in 48 h) from soil. In addition, MeBr was not detected in the leachate from the soil columns, however, bromide ion was detected at levels above background 48 h after fumigation and peaked at 5 weeks.

  18. Bromate oxidized from bromide during sonolytic ozonation.

    PubMed

    Lu, Ning; Wu, Xue-Fei; Zhou, Ji-Zhi; Huang, Xin; Ding, Guo-Ji

    2015-01-01

    Sonolytic ozonation (US/O3) is an effective way to degrade many pollutants in drinking water as the elevated mass transfer rate of ozone gas and the enhanced forming of hydroxyl radicals (OH). This work investigated the formation of bromate (BrO3(-)) from bromide (Br(-)) in sonolytic ozonation. At neutral pH, the bromate conversion rate ([BrO3(-)]/[Br(-)]0) was increased to 60% by ultrasound at continuous ozone flow (0-0.2Lmin(-1)), much higher than that without ultrasound or without bubbling. This indicates that the promoting effect of sonolysis on BrO3(-) formation is mainly due to the sonolytic decomposition of ozone and the enhancement of gas-liquid transfer. The [BrO3(-)]/[Br(-)]0 was increased with increasing pH. In addition, the reduction of HOBr/OBr(-) with ultrasound demonstrates that bromate may be inhibited as the bromide was formed with the H2O2 generation under ultrasound. This suggests the competition between bromate and bromide during the US/O3 led to the inhibition of bromate formation at high ozone flow. Therefore, our result reveals that the bromate formation under ultrasound is improved remarkably in US/O3 in quick treatment with proper ozone flow (<0.2Lmin(-1)). PMID:24931426

  19. [I(KACh) inhibitor 2-[(4-methylphenyl)sulfonylcarbamido]-1-(4-nitrobenzyl)pyridinium bromide (2-AP27) is a muscarinic M(2) receptor antagonist].

    PubMed

    Skeberdis, Vytenis Arvydas; Gendviliene, Vida; Zablockaite, Danguole; Martisiene, Irma; Stankevicius, Antanas

    2009-01-01

    Aminopyridines are known to inhibit acetylcholine-activated K(+) current (I(KACh)) in cardiac myocytes. The aim of this study was to examine the effect of 2-aminopyridine sulfonylcarbamide derivative 2-AP27 on isoprenaline-stimulated L-type Ca(2+) current (I(CaL)) and to identify whether 2-AP27 acts via blocking of muscarinic M(2)-receptors in frog cardiomyocytes. The whole-cell configuration of the patch-clamp technique was used to record I(CaL) in enzymatically isolated cardiac myocytes. Isoprenaline (0.1 microM), an agonist of beta(1)-beta(2)-adrenoreceptors, stimulated the I(CaL) up to 475+/-61% (n=4) (P<0.05) vs. control. Then, in the first series of experiments, carbachol (0.01 microM), an agonist of M(2 )muscarinic receptors, reduced the stimulatory effect of isoprenaline to 42+/-15% vs. isoprenaline alone. 2-AP27 (100 microM) alone completely abolished the inhibitory effect of carbachol on isoprenaline-stimulated I(CaL), which recovered to 95+/-5.8% of the effect of isoprenaline. In the second series of experiments, adenosine (1microM), an agonist of A(1)-adenosine receptors, reduced the stimulatory effect of isoprenaline on I(CaL) to 56+/-10% (n=3) (P<0.05). Then 2-AP27 (100 microM) applied in the presence of adenosine, had no effect on I(CaL), which remained at 51+/-7.9% (n=3) (P<0.05) of the effect of isoprenaline. These results suggest that 2-AP27, a new derivative of 2-AP, containing 4-toluolsulfonylcarbamide instead of amino group and quaternizated nitrogen by 4-nitrobenzylbromide in pyridine ring, is acting as an antagonist of muscarinic M(2) receptors in frog ventricular myocytes. PMID:19667745

  20. Bis[(E)-4-(hydroxy­imino­meth­yl)pyridinium] oxalate

    PubMed Central

    Seidel, Rüdiger W.; Winter, Manuela V.; Oppel, Iris M.

    2008-01-01

    The formula unit of the title compound, 2C6H7N2O+·C2O4 2−, comprises two symmetry-equivalent 4-(hydroxy­imino­meth­yl)­pyridinium cations on general positions, linked through hydrogen bonding via an oxalate anion that resides on a crystallographic centre of symmetry. The crystal structure consists of infinite chains of cations and oxalate anions directed by O—H⋯O and multicentre N—H⋯O inter­molecular hydrogen-bonding inter­actions. PMID:21200745

  1. Pyridinium-phosphonium dications: highly electrophilic phosphorus-based Lewis acid catalysts.

    PubMed

    Bayne, Julia M; Holthausen, Michael H; Stephan, Douglas W

    2016-04-14

    Using commercially available 2-pyridyldiphenylphosphine (o-NC5H4)PPh2, a family of electrophilic phosphonium cations [(o-NC5H4)PFPh2](+) (2) and dications [(o-MeNC5H4)PRPh2](2+) (R = F (4); Me (5)) were prepared. The Lewis acidity of these pyridinium-phosphonium dications was probed in Friedel-Crafts dimerization, hydrodefluorination, hydrosilylation, dehydrocoupling and hydrodeoxygenation reactions. The influence of the counterion on the catalytic activity of the electrophilic phosphonium cations is also discussed. PMID:26666332

  2. Bis[3-(2-carboxy­ethen­yl)pyridinium-1-acetato]dichloridozinc(II)

    PubMed Central

    Jing, Xue-Hui; Sun, Wei-Wei; Gao, En-Qing

    2009-01-01

    In the title complex, [ZnCl2(C10H9NO4)2], the ZnII ion lies on a twofold rotation axis and is four-coordinated by two carboxyl­ate O atoms from two 3-(2-carboxy­ethen­yl)pyridinium-1-acetate ligands in a monodentate mode and two Cl atoms in a distorted tetra­hedral geometry. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into a double-chain structure extending parallel to [101]. PMID:21578626

  3. Using Pyridinium Styryl Dyes as the Standards of Time-Resolved Instrument Response.

    PubMed

    Li, Lei; Chang, Mengfang; Yi, Hua; Jia, Menghui; Cao, Xiaodan; Zhou, Zhongneng; Zhang, Sanjun; Pan, Haifeng; Shih, Chun-Wei; Jimenez, Ralph; Xu, Jianhua

    2016-07-01

    In this paper, two pyridinium styryl dyes, [2-(4-dimethylamino-phenyl)-vinyl]-1-methylpyridinium iodide (DASPMI), were synthesized and characterized by steady state fluorescence spectroscopy as well as picosecond and femtosecond time-resolved fluorescence spectroscopies. Both dyes exhibit large Stokes shifts and fluorescence decays equivalent to the instrument response function (IRF) standards employed in time-correlated single-photon counting. Due to their styryl and pyridinium moieties, DASPMIs have higher peak fluorescence intensity and shorter excited-state lifetimes than iodide ion-quenched fluorophores. The fluorescence lifetimes of o-DASPMI and p-DASPMI were measured to be 6.6 ps and 12.4 ps, respectively. The fluorescence transients of these DASPMIs were used as the IRFs for iterative reconvolution fitting of the time-resolved fluorescence decay profiles of Rhodamine B (RhB), sulforhodamine B (SRB), and the SRB-SRB2m RNA aptamer complex. The quality of the fits employing the DASPMI-derived IRFs are consistently equivalent to those employing IRFs obtained from light scattering. These results indicate that DASPMI-derived IRFs may be suited for a broad range of applications in time-resolved spectroscopy and fluorescence lifetime imaging microscopy (FLIM), especially in the visible emission range. PMID:27231333

  4. Evaluation of Range-Corrected Density Functionals for the Simulation of Pyridinium-Containing Molecular Crystals.

    PubMed

    Ruggiero, Michael T; Gooch, Jonathan; Zubieta, Jon; Korter, Timothy M

    2016-02-18

    The problem of nonlocal interactions in density functional theory calculations has in part been mitigated by the introduction of range-corrected functional methods. While promising solutions, the continued evaluation of range corrections in the structural simulations of complex molecular crystals is required to judge their efficacy in challenging chemical environments. Here, three pyridinium-based crystals, exhibiting a wide range of intramolecular and intermolecular interactions, are used as benchmark systems for gauging the accuracy of several range-corrected density functional techniques. The computational results are compared to low-temperature experimental single-crystal X-ray diffraction and terahertz spectroscopic measurements, enabling the direct assessment of range correction in the accurate simulation of the potential energy surface minima and curvatures. Ultimately, the simultaneous treatment of both short- and long-range effects by the ωB97-X functional was found to be central to its rank as the top performer in reproducing the complex array of forces that occur in the studied pyridinium solids. These results demonstrate that while long-range corrections are the most commonly implemented range-dependent improvements to density functionals, short-range corrections are vital for the accurate reproduction of forces that rapidly diminish with distance, such as quadrupole-quadrupole interactions. PMID:26814572

  5. Physical Properties of Pyridinium Fluorohydrogenate, [pyridine · H+][H2F3]-

    NASA Astrophysics Data System (ADS)

    Hulse, Ryan; Singh, Rajiv

    2008-12-01

    Ionic liquids (ILs), also referred to as molten salts, have found application as electrolytes for batteries and super-capacitors, in electroplating baths, as designer solvents, and as reaction media. A few of the desired properties of a super-capacitor electrolyte are nonflammability, thermal stability, and electrochemical stability. ILs containing aromatic cations have been shown to have low viscosity which results in a high electrochemical conductivity. There is a delicate balance between increasing the thermal stability, or decreasing the melting point, and increasing the electrochemical conductivity of the IL. This study focuses on pyridinium fluorohydrogenate, [pyridine · H+][H2F3]-. Pyridinium fluorohydrogenate has been synthesized by the reaction of pyridine and anhydrous hydrofluoric acid. This IL has a relatively high electrical conductivity (~98 mS · cm-1 at 23 °C), a wide electrochemical window, and a boiling point of 186 °C. A stable gel can also be formed by combining [pyridine · H+][H2F3]- and a super absorbent polymer such as polyacrylic acid. The gel adds mechanical stability to the matrix while not greatly affecting the conductivity of the IL.

  6. Functional Role of Pyridinium during Aqueous Electrochemical Reduction of CO2 on Pt(111).

    PubMed

    Ertem, Mehmed Z; Konezny, Steven J; Araujo, C Moyses; Batista, Victor S

    2013-03-01

    Recent breakthroughs in electrochemical studies have reported aqueous CO2 reduction to formic acid, formaldehyde, and methanol at low overpotentials (-0.58 V versus SCE), with a Pt working electrode in acidic pyridine (Pyr) solutions. We find that CO2 is reduced by H atoms bound to the Pt surface that are transferred as hydrides to CO2 in a proton-coupled hydride transfer (PCHT) mechanism activated by pyridinium (PyrH(+)), CO2 + Pt-H + PyrH(+) + e(-) → Pyr + Pt + HCO2H. The surface-bound H atoms consumed by CO2 reduction is replenished by the one-electron reduction of PyrH(+) through the proton-coupled electron transfer (PCET), PyrH(+) + Pt + e(-) → Pyr + Pt-H. Pyridinium is essential to establish a high concentration of Brønsted acid in contact with CO2 and with the Pt surface, much higher than the concentration of free protons. These findings are particularly relevant to generate fuels with a carbon-neutral footprint. PMID:26281929

  7. 2,3-Diamino­pyridinium 2-hy­droxy­benzoate

    PubMed Central

    Hemamalini, Madhukar; Goh, Jia Hao; Fun, Hoong-Kun

    2011-01-01

    In the title mol­ecular salt, C5H8N3 +·C7H5O3 −, the 2,3-diamino­pyridinium cation is essentially planar, with a maximum deviation of 0.006 (2) Å. In the crystal, adjacent cations and anions are linked by pairs of N—H⋯O hydrogen bonds, generating R 2 2(8) loops. These dimers are linked by further N—H⋯O hydrogen bonds and C—H⋯O inter­actions to form sheets lying parallel to (001). A typical intra­molecular O—H⋯O hydrogen bond is also observed in the salicylate (2-hy­droxy­benzoate) anion, which generates an S(6) ring. The crystal structure also features π–π stacking inter­actions between the pyridinium rings of the cations, with a centroid–centroid distance of 3.5896 (15) Å. PMID:22220123

  8. Role of alkyl group in the aromatic extraction using pyridinium-based ionic liquids.

    PubMed

    Kim, Min Ji; Shin, Seung Hoon; Kim, Young Jin; Cheong, Minserk; Lee, Je Seung; Kim, Hoon Sik

    2013-11-27

    The performance of N-alkylpyridinium-based ionic liquids with a SCN anion (PyILs) was evaluated for the selective extraction of aromatics from aliphatic hydrocarbons. The aromatic extraction ability of PyILs was greatly enhanced by the presence of a methyl group on the pyridinium ring at the 3- or 4-position, whereas the solubility of the aromatics in the PyILs decreased with increasing the number of methyl groups on the benzene ring. The FT-IR studies revealed that the solubility of an aromatic compound in a PyIL is closely correlated with the degree of aromatic C-H bending frequency shift observed during the dissolution of the aromatic compound in the PyIL: the larger the shift, the higher the solubility. The computational calculations on the dispersion interactions between aromatics and PyILs demonstrated that the anion-aromatic interaction is much more important than the cation-aromatic interaction in determining the aromatic solubility in PyILs, and such anion-aromatic interaction can be enhanced by introducing a methyl group at the carbon atom of the pyridinium ring. PMID:24180561

  9. Properties of columns with several pyridinium and imidazolium ionic liquid stationary phases.

    PubMed

    Shashkov, M V; Sidelnikov, V N

    2013-09-27

    Recent advances in the development of new liquid phases (ILs) made it possible to use some classes of ILs as polar stationary liquid phases (SLP). In our days only alkylimidazolium- and alkylphosphonium-based ILs are widely used as polar SLP. In present work some other types of ILs - pyridinium and cyanopropyl/hydroxypropyl imidazolium were investigated as SLP. Columns with efficiencies 2000-2500 plates/m by high-pressure static method were prepared. Polarity and selectivity of these phases were measured. Selectivity was described in terms of intermolecular interactions by using Abraham solvatation parameter model. The set of the regularities between cation structure of ionic liquid and selectivity has been shown. The number and position of methyl groups in ionic liquid pyridinium ring were shown to have the sufficient influence on all type of molecular interactions. Finally the resolutions of test mixture for the several ionic liquid SLP were obtained. For columns with some ionic liquids the dependencies of the height equivalent to a theoretical plate (HETP) and sample loading capacity were obtained and compared with the conventional phases. It was found that the optimal efficiency for the IL columns is attained at lower carrier gas velocities in comparison with traditional phases. Nevetheless sample loading capacity of IL phases is comparable to those of conventional GC phases. PMID:23958690

  10. CuO nanostructures: optical properties and morphology control by pyridinium-based ionic liquids.

    PubMed

    Sabbaghan, Maryam; Shahvelayati, Ashraf Sadat; Madankar, Kamelia

    2015-01-25

    Copper oxide nanostructures have been synthesized by a simple reflux method in aqueous medium of pyridinium based ionic liquids. The structural and optical properties of CuO nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectroscopy (PL) and UV-visible. The morphologies of the nanostructures can be controlled by changing the amount of NaOH and ionic liquids. The results show that the use identical pyridinium based ionic liquids in ratio of 4:1 NaOH/Cu(OAc)2⋅H2O yield minor differences in morphology of CuO nanostructures. Different morphologies of CuO nanostructures were obtained by changing the ratio NaOH/Cu(OAc)2⋅H2O to 2:1. Ionic liquids play an important role on optical properties of CuO nanostructures. The results of optical measurements of the CuO nanostructures illustrate that band gaps are estimated to be 1.67-1.85 eV. PL patterns studies show that the ionic liquids can be effect on PL patterns of the samples. The reasons of these phenomena are discussed. PMID:25128679

  11. Pyridinium molten salts as co-adsorbents in dye-sensitized solar cells

    SciTech Connect

    Chang, Jui-Cheng; Sun, I-Wen; Yang, Cheng-Hsien; Yang, Hao-Hsun; Hsueh, Mao-Lin; Ho, Wen-Yueh; Chang, Jia-Yaw

    2011-01-15

    The influence of using pyridinium molten salts as co-adsorbents to modify the monolayer of a TiO{sub 2} semiconductor on the performance of a dye-sensitized solar cell is studied. The current-voltage characteristics are measured under AM 1.5 (100 mW cm{sup -2}). The pyridinium molten salts significantly enhance the open-circuit photovoltage (V{sub oc}), the short circuit photocurrent density (J{sub sc}) as well as the solar energy conversion efficiency ({eta}). 1-Ethyl-3-carboxypyridinium iodide ([ECP][I]) is applied successfully to prepare an insulating molecular layer with N719, and achieve high energy conversion efficiency as high as 4.49% at 100 mW cm{sup -2} and AM 1.5. The resulting efficiency is 20% higher than that of a non-additive device. This enhancement of conversion efficiency is attributed to the negative shift of the conduction band (CB) edge and the abundant concentration of I{sup -} on the surface of the electrode when using [ECP][I] as the co-adsorbent. (author)

  12. Europium-doped barium bromide iodide

    SciTech Connect

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  13. Advanced hydrogen electrode for hydrogen-bromide battery

    NASA Technical Reports Server (NTRS)

    Kosek, Jack A.; Laconti, Anthony B.

    1987-01-01

    Binary platinum alloys are being developed as hydrogen electrocatalysts for use in a hydrogen bromide battery system. These alloys were varied in terms of alloy component mole ratio and heat treatment temperature. Electrocatalyst evaluation, performed in the absence and presence of bromide ion, includes floating half cell polarization studies, electrochemical surface area measurements, X ray diffraction analysis, scanning electron microscopy analysis and corrosion measurements. Results obtained to date indicate a platinum rich alloy has the best tolerance to bromide ion poisoning.

  14. Rotamerism-driven large magnitude host-guest binding change in a crown ether derivatized pyridinium-phenolate series.

    PubMed

    Ay, Emel; Hobeika, Nelly; Chaumeil, Hélène; Tschamber, Théophile; Jin, Ming; Versace, Davy-Louis; Malval, Jean-Pierre

    2016-03-17

    Two TICTOID-based pyridinium-phenolates bearing a crown ether macrocycle have been designed for the complexation of a potassium cation. The nucleophilicity of the intraannular phenolate -O(-) function can be strongly modulated by biaryl twisting. Such a structure/electronic transduction effect gives rise to a host-guest binding change by more than two orders of magnitude. PMID:26948128

  15. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Methyl bromide; tolerances for residues. 180.124 Section 180.124 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.124 Methyl bromide; tolerances...

  16. An Ill Wind: Methyl Bromide Use Near California Schools, 1998.

    ERIC Educational Resources Information Center

    Ross, Zev; Walker, Bill

    A California study investigates the use of the toxic pesticide methyl bromide near the state's public schools, explains why proposed safety rules have failed to protect children and others from exposure, and examines regions at particular exposure risk. Study results show an increasing exposure to methyl bromide near schools already at risk while…

  17. 40 CFR 180.124 - Methyl bromide; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Methyl bromide; tolerances for residues. 180.124 Section 180.124 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.124 Methyl bromide; tolerances...

  18. Interaction of methyl bromide with soil.

    PubMed

    Tao, Ting; Maciel, Gary E

    2002-02-15

    Because methyl bromide (CH3Br) is a widely used agricultural fumigant for soil disinfection, it is important to know the chemical behavior and fate of CH3Br as a result of its use for soil treatment. A solid-state 13C NMR study of 13CH3Br-treated soil and soil-component samples shows that methylation of soil organic matter may be the major pathway for degradation of CH3Br in soils. Adsorption of CH3Br on a dried clay like Ca-montmorillonite or kaolinite does not contribute directly to the degradation of CH3Br. The results are interpreted in terms of the chemical structures of separated soil fractions and the nature of the separation procedure. PMID:11878373

  19. Degradation of methyl bromide in anaerobic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Miller, L.G.; Strohmaler, F.E.

    1994-01-01

    Methyl bromide (MeBr) was anaerobically degraded in saltmarsh sediments after reaction with sulfide. The product of this nucleophilic substitution reaction was methanethiol, which underwent further chemical and bacterial reactions to form dimethyl sulfide. These two gases appeared transiently during sediment incubations because they were metabolized by methanogenic and sulfate-reducing bacteria. A second, less significant reaction of MeBr was the exchange with chloride, forming methyl chloride, which was also susceptible to attack by sulfide. Incubation of 14C-labeled methyl iodide as an analogue of MeBr resulted in the formation of 14CH4 and 14CO2 and also indicated that sulfate-reducing bacteria as well as methanogens metabolized the methylated sulfur intermediates. These results suggest that exposed sediments with abundant free sulfide, such as coastal salt-marshes, may constitute a sink for atmospheric MeBr.

  20. Single ion dynamics in molten sodium bromide

    SciTech Connect

    Alcaraz, O.; Trullas, J.; Demmel, F.

    2014-12-28

    We present a study on the single ion dynamics in the molten alkali halide NaBr. Quasielastic neutron scattering was employed to extract the self-diffusion coefficient of the sodium ions at three temperatures. Molecular dynamics simulations using rigid and polarizable ion models have been performed in parallel to extract the sodium and bromide single dynamics and ionic conductivities. Two methods have been employed to derive the ion diffusion, calculating the mean squared displacements and the velocity autocorrelation functions, as well as analysing the increase of the line widths of the self-dynamic structure factors. The sodium diffusion coefficients show a remarkable good agreement between experiment and simulation utilising the polarisable potential.

  1. Glycopyrronium bromide for the treatment of chronic obstructive pulmonary disease.

    PubMed

    Riario-Sforza, Gian Galeazzo; Ridolo, Erminia; Riario-Sforza, Edoardo; Incorvaia, Cristoforo

    2015-02-01

    Glycopyrronium bromide is a new long-acting muscarinic antagonist to be used once-daily, which is approved as a bronchodilator for the symptomatic maintenance treatment of adult patients with chronic obstructive pulmonary disease (COPD). In the Glycopyrronium bromide in chronic Obstructive pulmonary disease airWays trials, treatment with inhaled glycopyrronium bromide at 50 μg once daily achieved a significantly better lung function than placebo, as measured by the trough forced expiratory volume in 1 s in patients with moderate-to-severe COPD. The lung function improvement was maintained for up to 52 weeks. Other improved indexes were dyspnea scores, health status, exacerbation rates and time of exercise endurance. Studies comparing the efficacy of glycopyrronium versus tiotropium bromide found substantial equivalence of the two drugs. Glycopyrronium was generally well tolerated. These data add inhaled glycopyrronium bromide to the treatment of patients with moderate to severe COPD as an effective once-daily LAMA. PMID:25547422

  2. Atmosphere-plant canopy interactions of methyl bromide

    SciTech Connect

    Taylor, G.E. Jr.; Leonard, T.D.; Gustin, M.S.

    1995-12-31

    In the planetary boundary layer, parcels of air containing background and elevated concentrations of methyl bromide commonly pass through plant canopies in managed (agriculture) and natural (forests, grasslands) ecosystems. It is hypothesized that leaf surfaces are a significant sink or methyl bromide on a local and regional scale and that failure to account for this sink results in a significant overestimation of methyl bromide transport to the stratosphere. Using highly controlled environments, studies are investigating the reactivity of leaf surfaces for methyl bromide at elevated and global background concentrations. Estimates of pathway resistances are being calculated and sites of deposition determined. The results indicate that plant canopies are a significant unrecognized sink for methyl bromide in the atmosphere.

  3. Secondary interactions in N-(chloromethyl)pyridinium chlorides (n = 2, 3, 4).

    PubMed

    Jones, Peter G; Vancea, Fabiola; Herbst-Irmer, Regine

    2002-11-01

    In the isomeric title compounds, viz. 2-, 3- and 4-(chloromethyl)pyridinium chloride, C(6)H(7)ClN(+).Cl(-), the secondary interactions have been established as follows. Classical N-H.Cl(-) hydrogen bonds are observed in the 2- and 3-isomers, whereas the 4-isomer forms inversion-symmetric N-H(.Cl(-).)(2)H-N dimers involving three-centre hydrogen bonds. Short Cl.Cl contacts are formed in both the 2-isomer (C-Cl.Cl(-), approximately linear at the central Cl) and the 4-isomer (C-Cl.Cl-C, angles at Cl of ca 75 degrees ). Additionally, each compound displays contacts of the form C-H.Cl, mainly to the Cl(-) anion. The net effect is to create either a layer structure (3-isomer) or a three-dimensional packing with easily identifiable layer substructures (2- and 4-isomers). PMID:12415176

  4. Fluorescence upconversion properties of a class of improved pyridinium dyes induced by two-photon absorption

    NASA Astrophysics Data System (ADS)

    Xu, Guibao; Hu, Dawei; Zhao, Xian; Shao, Zongshu; Liu, Huijun; Tian, Yupeng

    2007-06-01

    We report the fluorescence upconversion properties of a class of improved pyridinium toluene- p-sulfonates having donor- π-acceptor (D- π-A) structure under two-photon excitation at 1064 nm. The experimental results show that both the two-photon excited (TPE) fluorescence lifetime and the two-photon pumped (TPP) energy upconversion efficiency were increased with the enhancement of electron-donating capability of the donor in the molecule. It is also indicated that an overlong alkyl group tends to result in a weakened molecular conjugation, leading to a decreased two-photon absorption (TPA) cross section. By choosing the donor, we can obtain a longest fluorescence lifetime of 837 ps, a highest energy upconversion efficiency of ˜6.1%, and a maximum TPA cross-section of 8.74×10 -48 cm 4 s/photon in these dyes.

  5. Antiradiation compounds. 20. 1-Methylquinolinium(and pyridinium)-2-dithioacetic acid derivatives

    SciTech Connect

    Foye, W.O.; Jones, R.W.; Ghoshal, P.K.; Almassian, B.

    1987-01-01

    A new class of radiation-protective compounds has been found in the bis(methylthio) and methylthio amino derivatives of 1-methylquinolinium- and 1-methylpyridinium-2-dithioacetic acids. The compounds gave good protection to mice vs. 1000-rad gamma-radiation in ip doses of 10 mg/kg or less, much lower than those required for the aminoalkyl thiols (approximately 150-600 mg/kg). The dithioacetic acid zwitterions were prepared from the base-catalyzed reaction of carbon disulfide with quinaldine and picoline methiodides, and the bis(methylthio) derivatives resulted from reaction with methyl iodide at room temperature. Replacement of one methylthio moiety took place readily on reaction of the bis(methylthio) derivatives with 1 molar equiv of an amine. The best protective activity was found with the methylthio piperidino derivative in both the quinolinium and pyridinium series.

  6. Structure-activity correlation in transfection promoted by pyridinium cationic lipids.

    PubMed

    Parvizi-Bahktar, P; Mendez-Campos, J; Raju, L; Khalique, N A; Jubeli, E; Larsen, H; Nicholson, D; Pungente, M D; Fyles, T M

    2016-03-21

    The efficiency of the transfection of a plasmid DNA encoding a galactosidase promoted by a series of pyridinium lipids in mixtures with other cationic lipids and neutral lipids was assessed in CHO-K1 cells. We identify key molecular parameters of the lipids in the mixture - clog P, lipid length, partial molar volume - to predict the morphology of the lipid-DNA lipoplex and then correlate these same parameters with transfection efficiency in an in vitro assay. We define a Transfection Index that provides a linear correlation with normalized transfection efficiency over a series of 90 different lipoplex compositions. We also explore the influence of the same set of molecular parameters on the cytotoxicity of the formulations. PMID:26891970

  7. Electrochemical and spectroscopic studies of sulfur in aluminum chloride-N-(n-butyl)pyridinium chloride

    SciTech Connect

    Marassi, R.; Laher, T.M.; Mamantov, G.; Trimble, D.S.

    1985-07-01

    The behavior of sulfur in aluminum chloride-N-(n-butyl)pyridinium chloride (AlCl/sub 3/-BPC) was studied using Raman spectroscopy and electrochemical techniques. In basic (BPC-rich) melts, sulfur can be reduced to sulfide, probably in the form of an AlSCl-like species. No oxidation to positive oxidation states of sulfur is observed in basic melts. In acidic (AlCl/sub 3/-rich) melts, sulfur can be oxidized to S(I) and eventually to S(IV), which is only stabl in the melt for short periods of time. No reduction to sulfide-like species or formation of low oxidation states is observed in acidic melts.

  8. Infrared and Ultraviolet Spectroscopy of Gas-Phase Imidazolium and Pyridinium Ionic Liquids.

    NASA Astrophysics Data System (ADS)

    Young, Justin W.; Booth, Ryan S.; Annesley, Christopher; Stearns, Jaime A.

    2015-06-01

    Ionic liquids (ILs) are a highly variable and potentially game-changing class of molecules for a number of Air Force applications such as satellite propulsion, but the complex nature of IL structure and intermolecular interactions makes it difficult to adequately predict structure-property relationships in order to make new IL-based technology a reality. For example, methylation of imidazolium ionic liquids leads to a substantial increase in viscosity but the underlying physical mechanism is not understood. In addition, the role of hydrogen bonding in ILs, and especially its relationship to macroscopic properties, is a matter of ongoing research. Here we describe the gas-phase spectroscopy of a series of imidazolium- and pyridinium-based ILs, using a combination of infrared spectroscopy and density functional theory to establish the intermolecular interactions present in various ILs, to assess how well they are described by theory, and to relate microscopic structure to macroscopic properties.

  9. Novel pyridinium based cobalt carbonyl ionic liquids: synthesis, full characterization, crystal structure and application in catalysis.

    PubMed

    Deng, Fan-Guo; Hu, Bin; Sun, Wei; Chen, Jing; Xia, Chun-Gu

    2007-10-10

    Through an optimized synthetic strategy, a series of novel alkylpyridinium cobalt tetracarbonyl salts, [C(1)Py][Co(CO)(4)] (), [C(4)Py][Co(CO)(4)] () and [C(16)Py][Co(CO)(4)] () (C(n)Py = N-C(n)H(2n+1)-pyridinium), were successfully prepared in good yields, using a water-organic biphasic system. All the three compounds melt well below 100 degrees C and could be classified as ionic liquids. The compounds were fully characterized using IR, UV-Vis, (1)H NMR, (13)C NMR, ESI-MS and elemental analysis, and was structurally characterized by X-ray single crystal analysis. Compound has been found to be an efficient and reusable catalyst for the alkoxycarbonylation of propylene oxide without the aid of a base additive. PMID:17893815

  10. Oxidative desulfurization of fuel oil by pyridinium-based ionic liquids.

    PubMed

    Zhao, Dishun; Wang, Yanan; Duan, Erhong

    2009-01-01

    In this work, an N-butyl-pyridinium-based ionic liquid [BPy]BF(4) was prepared. The effect of extraction desulfurization on model oil with thiophene and dibenzothiophene (DBT) was investigated. Ionic liquids and hydrogen peroxide (30%) were tested in extraction-oxidation desulfurization of model oil. The results show that the ionic liquid [BPy]BF(4) has a better desulfurization effect. The best technological conditions are: V(IL)/V(Oil) /V(H(2)O(2)) = 1:1:0.4, temperature 55 degrees C, the time 30 min. The ratio of desulfurization to thiophene and DBT reached 78.5% and 84.3% respectively, which is much higher than extraction desulfurization with simple ionic liquids. Under these conditions, the effect of desulfurization on gasoline was also investigated. The used ionic liquids can be recycled up to four times after regeneration. PMID:19924069

  11. Atomistic force field for pyridinium-based ionic liquids: reliable transport properties.

    PubMed

    Voroshylova, Iuliia V; Chaban, Vitaly V

    2014-09-11

    Reliable force field (FF) is a central issue in successful prediction of physical chemical properties via computer simulations. This work introduces refined FF parameters for six popular ionic liquids (ILs) of the pyridinium family (butylpyridinium tetrafluoroborate, bis(trifluoromethanesulfonyl)imide, dicyanamide, hexafluorophosphate, triflate, chloride). We elaborate a systematic procedure, which allows accounting for specific cation-anion interactions in the liquid phase. Once these interactions are described accurately, all experimentally determined transport properties can be reproduced. We prove that three parameters per interaction site (atom diameter, depth of potential well, point electrostatic charge) provide a sufficient basis to predict thermodynamics (heat of vaporization, density), structure (radial distributions), and transport (diffusion, viscosity, conductivity) of ILs at room conditions and elevated temperature. The developed atomistic models provide a systematic refinement upon the well-known Canongia Lopes-Pádua (CL&P) FF. Together with the original CL&P parameters the present models foster a computational investigation of ionic liquids. PMID:25144141

  12. Collective ion diffusion and localized single particle dynamics in pyridinium-based ionic liquids.

    PubMed

    Burankova, Tatsiana; Hempelmann, Rolf; Wildes, Andrew; Embs, Jan P

    2014-12-11

    Quasielastic neutron scattering with polarized neutrons allows for an experimental separation of single-particle and collective processes, as contained in the incoherent and coherent scattering contributions. This technique was used to investigate the dynamical processes in the pyridinium-based ionic liquid 1-butylpyridinium bis(trifluoromethylsulfonyl)-imide. We observed two diffusion processes with different time scales. The slower diffusional process was present in both the coherent and the incoherent contribution, meaning that this process has at least a partial collective nature. The second faster localized process is only present in the incoherent scattering contribution. We conclude that it is a true single-particle process on a shorter time scale. PMID:25387035

  13. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...

  14. 49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...

  15. Selective oxidation of bromide in wastewater brines from hydraulic fracturing.

    PubMed

    Sun, Mei; Lowry, Gregory V; Gregory, Kelvin B

    2013-07-01

    Brines generated from oil and natural gas production, including flowback water and produced water from hydraulic fracturing of shale gas, may contain elevated concentrations of bromide (~1 g/L). Bromide is a broad concern due to the potential for forming brominated disinfection byproducts (DBPs) during drinking water treatment. Conventional treatment processes for bromide removal is costly and not specific. Selective bromide removal is technically challenging due to the presence of other ions in the brine, especially chloride as high as 30-200 g/L. This study evaluates the ability of solid graphite electrodes to selectively oxidize bromide to bromine in flowback water and produced water from a shale gas operation in Southwestern PA. The bromine can then be outgassed from the solution and recovered, as a process well understood in the bromine industry. This study revealed that bromide may be selectively and rapidly removed from oil and gas brines (~10 h(-1) m(-2) for produced water and ~60 h(-1) m(-2) for flowback water). The electrolysis occurs with a current efficiency between 60 and 90%, and the estimated energy cost is ~6 kJ/g Br. These data are similar to those for the chlor-alkali process that is commonly used for chlorine gas and sodium hydroxide production. The results demonstrate that bromide may be selectively removed from oil and gas brines to create an opportunity for environmental protection and resource recovery. PMID:23726709

  16. Theoretical study for pyridinium-based ionic liquid 1-ethylpyridinium trifluoroacetate: synthesis mechanism, electronic structure, and catalytic reactivity.

    PubMed

    Zhu, Xueying; Cui, Peng; Zhang, Dongju; Liu, Chengbu

    2011-07-28

    By performing density functional theory calculations, we have studied the synthesis mechanism, electronic structure, and catalytic reactivity of a pyridinium-based ionic liquid, 1-ethylpyridinium trifluoroacetate ([epy](+)[CF(3)COO](-)). It is found that the synthesis of the pyridinium salt follows a S(N)2 mechanism. The electronic structural analyses show that multiple H bonds are generally involved in the pyridinium-based ionic liquid, which may play a decisive role for stabilizing the ionic liquid. The cation-anion interaction mainly involves electron transfer between the lone pair of the oxygen atom in the anion and the antibonding orbital of the C*-H bond (C* denotes the carbon atom at the ortho-position of nitrogen atom in the cation). This present work has also given clearly the catalytic mechanism of [epy](+)[CF(3)COO](-) toward to the Diels-Alder (D-A) reaction of acrylonitrile with 2-methyl-1,3-butadiene. Both the cation and anion are shown to play important roles in promoting the D-A reaction. The cation [epy](+), as a Lewis acid, associates the C≡N group by C≡N···H H bond to increase the polarity of the C═C double bond in acrylonitrile, while the anion CF(3)COO(-) links with the methyl group in 2-methyl-1,3-butadiene by C-H···O H bond, which weakens the electron-donating capability of methyl and thereby lowers the energy barrier of the D-A reaction. The present results are expected to provide valuable information for the design and application of pyridinium-based ionic liquids. PMID:21671599

  17. Conformation and interactions of 4-(pyridinium-1-yl)-phenolate betaine-dye and its cation in the crystalline state

    NASA Astrophysics Data System (ADS)

    Wojtas, Łukasz; Pawlica, Dariusz; Stadnicka, Katarzyna

    2006-03-01

    The crystals of 4-(pyridinium-1-yl)-phenolate dihydrate, 1-(4-hydroxyphenyl)-pyridynium chloride monohydrate, 1-(4-hydroxyphenyl)-pyridynium phosphate dihydrate were obtained to explore the molecular behaviour of the simplest pyridynium betaine-dye in various crystalline environments. 4-(Pyridinium-1-yl)-phenolate ( 1), as a push-pull chromophore showing the negative solvatochromism of ICT band, can be useful in NLO applications if the polar dipole arrangement is achieved in the solid-state. The attempt to overcome the tendency of betaine dipoles to form anti-parallel arrangements was successful to some extent. X-ray structure analysis of the crystals, obtained from aqueous solutions, revealed space groups Pnna, P212121 and P2 1/ c, respectively. For 4-(pyridinium-1-yl)-phenolate dihydrate and 1-(4-hydroxyphenyl)-pyridynium chloride monohydrate, the anti-parallel arrangements of the betaine-dye molecules/cations force a nonpolar space group. In the centrosymmetrical crystals of 1-(4-hydroxyphenyl)-pyridynium phosphate dihydrate, between the centrosymmetric layers built of phosphate anions and water molecules, there are the polar arrangement of the betaine-dye cations connected to the phosphate-hydrate layers; however, the centrosymmetricity of the layers precludes the polarity of the structure. The alteration of geometrical parameters of the cation, as compared to 4-(pyridinium-1-yl)-phenolate molecule, is observed only in the phenolate moiety due to the protonation of the oxygen atom. A twisted conformation for the betaine-dye molecule observed in the crystalline state, with the dihedral angle of 47.0(1)°, is similar to the results of computational studies for the ground state of the single molecule in an aqueous solution. The influence of crystal environment, and that of the oxygen atom protonation, on the variation of the torsion angle is small.

  18. Lithium bromide chiller technology in gas processing

    SciTech Connect

    Huey, M.A.; Leppin, D.

    1995-12-31

    Lithium Bromide (LiBr) Absorption Chillers have been in use for more than half a century, mainly in the commercial air conditioning industry. The Gas Research Institute and EnMark Natural Gas Company co-funded a field test to determine the viability of this commercial air conditioning technology in the gas industry. In 1991, a 10 MMCFC natural gas conditioning plant was constructed in Sherman, Texas. The plant was designed to use a standard, off-the-shelf chiller from Trane with a modified control scheme to maintain tight operating temperature parameters. The main objective was to obtain a 40 F dewpoint natural gas stream to meet pipeline sales specifications. Various testing performed over the past three years has proven that the chiller can be operated economically and on a continuous basis in an oilfield environment with minimal operation and maintenance costs. This paper will discuss how a LiBr absorption chiller operates, how the conditioning plant performed during testing, and what potential applications are available for LiBr chiller technology.

  19. Pyridinium quenchers of Ru(bpy)/sub 3//sup 2 +/ charge effects of the yield of electron transfer

    SciTech Connect

    Jones, G. II.; Malba, V.

    1985-12-27

    The quenching of the luminescent state of tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)/sub 3//sup 2 +/) by a series of pyridinium ions has been studied. 4-Acetyl-, 4-cyano-, 4-carbomethoxy-, or 4-carboxy-1-methylpyridinium, along with the well-known electron-transfer agent methyl viologen (MV/sup 2 +/), were employed as electron-acceptor quenchers in order to reveal the effects of charge type on the yield of photoinduced electron transfer involving the Ru(II) luminescent state as electron donor. Rates of quenching by the pyridinium ions were measured by using steady irradiation techniques and compared with expectations based on the calculated energetics of electron transfer. Electron transfer yields were obtained by measurement of the transient absorbances of photogenerated radicals (e.g., pyridinyls) using conventional flash photolysis (broad band visible excitation, pH 5, ..mu.. = 0.5). The transient photoleaching of Ru(bpy)/sub 3//sup 2 +/ by 4-carboxy-1-methylpyridinium was studied by using a Nd:YAG laser with results showing pH control of the charge type and yield of net electron transfer due to in-cage protonation of photogenerated geminate radical pairs. The electrochemical properties of the pyridinium ions were also examined by cyclic voltammetry and a Hammett correlation was made of the reduction potentials.

  20. Health and Environmental Effects Profile for methyl bromide

    SciTech Connect

    Not Available

    1986-06-01

    The Health and Environmental Effects Profile for methyl bromide was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency actions under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Both published literature and information obtained from Agency program office files were evaluated as they pertained to potential human health, aquatic life, and environmental effects. Quantitative estimates are presented provided sufficient data are available. Methyl bromide has been determined to be a systemic toxicant. An Acceptable Daily Intake (ADI), for methyl bromide is 0.0014 mg/kg/day for oral exposure. The Reportable Quantity (RQ) value for methyl bromide is 100.

  1. Kinetics and Mechanism of the Chlorate-Bromide Reaction.

    PubMed

    Sant'Anna, Rafaela T P; Faria, Roberto B

    2015-11-01

    The chlorate-bromide reaction, ClO3(-) + 6Br(-) + 6H(+) → 3Br2 + Cl(-) + 3H2O, was followed at the Br3(-)/Br2 isosbestic point (446 nm). A fifth-order rate law was found: (1)/3 d[Br2]/dt = k[ClO3(-)][Br(-)][H(+)](3) (k = 5.10 × 10(-6) s(-1) L(4) mol(-4)) at 25 °C and I = 2.4 mol L(-1). At high bromide concentrations, the bromide order becomes close to zero, indicating a saturation profile on bromide concentration, similar to the chloride saturation profile observed in the chlorate-chloride reaction. A mechanism is proposed that considers the formation of the intermediate BrOClO2(2-), similar to the intermediate ClOClO2(2-) proposed in the mechanism of the chlorate-chloride reaction. PMID:26467822

  2. The oceans: A source or a sink of methyl bromide?

    SciTech Connect

    Pilinis, C.; King, D.B.; Saltzman, E.S.

    1996-04-15

    The global ocean/atmosphere flux of methyl bromide has been estimated from shipboard measurements of the saturation anomaly. When such data are extrapolated globally on the basis of constant saturation anomaly, the ocean is a net sink for methyl bromide [Lobert et al.]. The same data can also be extrapolated on the basis of steady-state production rate of methyl bromide in the water column, allowing regional and seasonal variations in temperature to affect the saturation anomaly. The authors have carried out this type of extrapolation, and they found that the oceans are a strong net source of methyl bromide to the atmosphere. The difference arises mainly due to slow degradation rates in water of higher latitudes. A reduction of the applied production rate by more than 35% is needed in order to switch the ocean from a source to a sink of methyl bromide. These results demonstrate the sensitivity of current estimates of oceanic flux to assumptions about methyl bromide production and destruction in the water column. 19 refs., 2 fig.

  3. The toxic chemistry of methyl bromide.

    PubMed

    Bulathsinghala, A T; Shaw, I C

    2014-01-01

    Methyl bromide (MeBr) is a chemically reactive compound that has found use as a fire retardant and fumigant used for wood, soil, fruits and grains. Its use is banned in many countries because of its ozone-depleting properties. Despite this ban, the use of MeBr persists in some parts of the world (e.g. New Zealand) due to its important role in maintaining strict biosecurity of exported and imported products. Its high chemical reactivity leads to a broad toxicological profile ranging from acute respiratory toxicity following inhalation exposure, through carcinogenicity to neurotoxicty. In this article, we discuss the chemistry of MeBr in the context of its mechanisms of toxicity. The chemical reactivity of MeBr clearly underlies its toxicity. Bromine (Br) is electronegative and a good leaving group; the δ+ carbon thus facilitates electrophilic methylation of biological molecules including glutathione (GSH) via its δ- sulphur atom, leading to downstream effects due to GSH depletion. DNA alkylation, either directly by MeBr or indirectly due to reduction in GSH-mediated detoxification of reactive alkylating chemical species, might explain the carcinogenicity of MeBr. The neurotoxicity of MeBr is much more difficult to understand, but we speculate that methyl phosphates formed in cells might contribute to its neurone-specific toxicity via cholinesterase inhibition. Finally, evidence reviewed shows that it is unlikely for Br⁻ liberated by the metabolism of MeBr to have any toxicological effect because the Br⁻ dose is very low. PMID:23800997

  4. Assessment of Ethidium bromide and Ethidium monoazide bromide removal from aqueous matrices by adsorption on cupric oxide nanoparticles.

    PubMed

    Fakhri, Ali

    2014-06-01

    The present study was undertaken to develop an effective adsorbent and to study the adsorption of Ethidium bromide and Ethidium monoazide bromide from aqueous solution using the CuO nanoparticles. The characteristics of CuO nanoparticles were determined and found to have a surface area 89.59m(2)/g. Operational parameters such as pH, contact time and adsorbent concentration, initial concentration and temperature were also studied. The amount of removal increases with the increase in pH from one to seven and reaches the maximum when the pH is nine. Adsorption data fitted well with the Langmuir, Freundlich and Florry-Huggins models. The results show that the best fit was achieved with the Langmuir isotherm equation with maximum adsorption capacities of 0.868 and 0.662mg/g for Ethidium bromide and Ethidium monoazide bromide, respectively. The adsorption process was found to follow pseudo-second-order kinetics. The calculated thermodynamic parameters, namely ΔG, ΔH and ΔS showed that adsorption of Ethidium bromide and Ethidium monoazide bromide was spontaneous and endothermic under examined conditions. PMID:24630576

  5. Charged tag founded in N-(1-chloroalkyl)pyridinium quaternization for quantification of fatty aldehydes.

    PubMed

    Cao, Yanjing; Guan, Qing; Sun, Tuanqi; Qi, Wanshu; Guo, Yinlong

    2016-09-21

    N-(1-chloroalkyl)pyridinium quaternization was developed for the derivatization of fatty aldehydes. Differing from common pre-charged reagents, non-charged pyridine and thionyl chloride were designed to add permanently charged tag on aldehydes. Pyridine was far less competitive than charged derivatives in ionization. Thionyl chloride in excess was quenched by deionized water, converting into less residual sulfur dioxide bubbles. Thus solutions could be tested directly by mass spectrometry without further post-treatments. Pyridine-d5 labeled fatty aldehydes were prepared as internal standards. Mixed derivatives were then analyzed by high performance liquid chromatography coupled to positive electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Analytical parameters including reaction yield, stability, precision, linearity, and detection limits (LODs < 0.3 pg mL(-1)) were carefully validated. This method facilitated the analysis low content (ng mL(-1)) levels of free aliphatic aldehydes (C6C18) in human thyroid carcinoma and para-carcinoma tissue with a simple pretreatment procedure. Content of long chain nonvolatile aldehydes (C10C18) remarkably increased in thyroid carcinoma tissues (p < 0.05). PMID:27590548

  6. Growth and characterization of dexterous nonlinear optical material: Dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP)

    NASA Astrophysics Data System (ADS)

    Saravanan, M.

    2016-08-01

    The crystals (dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol [DMAPNP] suitable for NLO applications were grown by the slow cooling method. The solubility and metastable zone width measurement of DMAPNP specimen was studied. The material crystallizes in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The ocular precision in the intact visible region was found to be good for non-linear optical claim. Quality of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of DMAPNP sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The third order nonlinear optical properties of DMAPNP crystals were premeditated by Z-scan method. Birefringence and optical homogeneity of the crystal were evaluated using modified channel spectrum method. The half wave voltage of the grown crystal deliberate from the elector optic experimentation. Photoconductivity measurement specified consummate of inducing dipoles owing to brawny incident radiation and also disclose the nonlinear activities of the grown specimen.

  7. Free energy of solvation of carbon nanotubes in pyridinium-based ionic liquids.

    PubMed

    Chaban, Vitaly V; Fileti, Eudes Eterno

    2016-07-27

    Numerous prospective applications require the availability of individual carbon nanotubes (CNTs). Pristine CNTs, strongly hydrophobic in nature, are known to be either totally insoluble or poorly dispersible. While it is unlikely to be possible to prepare a real solution of CNTs in any solvent, the ability of certain solvents to maintain dispersions of CNTs for macroscopic times constitutes great research interest. In the present work, we characterize two pyridinium-based ionic liquids (ILs), N-butylpyridinium chloride [BPY][Cl] and N-butylpyridinium bis(trifluoromethanesulfonyl)imide [BPY][TFSI], with respect to their potential to solvate CNTs of different diameters, from the CNT (10,10) to the CNT (25,25). Using a universal methodology, we found that both ILs exhibit essentially the same solvation performance. Solvation of CNTs is strongly prohibited entropically, whereas the energy penalty increases monotonically with the CNT diameter. Weak van der Waals interactions, which guide enthalpy alteration upon the CNT solvation, are unable to compensate for the large entropic penalty from the destruction of the IL-IL electrostatic interactions. The structure of ILs inside and outside CNTs is also discussed. The reported results are necessary for gaining a fundamental understanding of the CNT solvation problems, thereby inspiring the search for more suitable solvents. PMID:27400869

  8. Full-color tunable photoluminescent ionic liquid crystals based on tripodal pyridinium, pyrimidinium, and quinolinium salts.

    PubMed

    Tanabe, Kana; Suzui, Yuko; Hasegawa, Miki; Kato, Takashi

    2012-03-28

    Color-tunable luminescent ionic liquid crystals have been designed as a new series of luminescent materials. To achieve tuning of emission colors, intramolecular charge transfer (ICT) character has been incorporated into tripodal molecules. A series of the compounds has three chromophores in each molecule, incorporated with both electron-donating moieties such as alkylaminobenzene and alkoxybenzene, and electron-accepting moieties such as pyridinium, pyrimidinium, and quinolinium parts. These C(3)-symmetrical molecules self-assemble into liquid-crystalline (LC) columnar (Col) structures over wide temperature ranges through nanosegregation between ionic moieties and nonionic aliphatic chains. Photoluminescent (PL) emissions of these tripodal molecules are observed in the visible region both in the self-assembled condensed states and in solutions. For example, a pyrimidinium salt with didodecylaminobenzene moieties exhibits yellowish orange emission (λ(em) = 586 nm in a thin film). Multicolor PL emissions are successfully achieved by simple tuning of changing electron-donating and electron-accepting moieties of the compounds, covering the visible region from blue-green to red. It has been revealed that ICT processes in the excited states and weak intermolecular interactions play important roles in the determination of the PL properties of the materials, by measurements of UV-vis absorption and emission spectra, fluorescence lifetimes, and PL quantum yields. PMID:22372372

  9. Two-stage prediction of the effects of imidazolium and pyridinium ionic liquid mixtures on luciferase.

    PubMed

    Ge, Hui-Lin; Liu, Shu-Shen; Su, Bing-Xia; Zhu, Xiang-Wei

    2014-01-01

    The predicted toxicity of mixtures of imidazolium and pyridinium ionic liquids (ILs) in the ratios of their EC50, EC10, and NOEC (no observed effect concentration) were compared to the observed toxicity of these mixtures on luciferase. The toxicities of EC50 ratio mixture can be effectively predicted by two-stage prediction (TSP) method, but were overestimated by the concentration addition (CA) model and underestimated by the independent action (IA) model. The toxicities of EC10 ratio mixtures can be basically predicted by TSP and CA, but were underestimated by IA. The toxicities of NOEC ratio mixtures can be predicted by TSP and CA in a certain concentration range, but were underestimated by IA. Our results support the use of TSP as a default approach for predicting the combined effect of different types of ILs at the molecular level. In addition, mixtures of ILs mixed at NOEC and EC10 could cause significant effects of 64.1% and 97.7%, respectively. Therefore, we should pay high attention to the combined effects in mixture risk assessment. PMID:24858273

  10. Phase equilibria and modeling of pyridinium-based ionic liquid solutions.

    PubMed

    Domańska, Urszula; Królikowski, Marek; Ramjugernath, Deresh; Letcher, Trevor M; Tumba, Kaniki

    2010-11-25

    The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM(4)Py][NTf(2)]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM(4)Py][NTf(2)] with all solvents reveal eutectic systems with regards to (solid-liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid-liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridinium-based ILs. The influence of the anion of the IL on the phase behavior has been discussed. PMID:20964426

  11. Experimental evidence of dual emission in a negatively solvatochromic push-pull pyridinium derivative.

    PubMed

    Carlotti, B; Cesaretti, A; Fortuna, C G; Spalletti, A; Elisei, F

    2015-01-21

    We report here experimental evidence of dual emission in a cationic push-pull system (bearing a methyl pyridinium group as an electron acceptor and a diphenylamino group as an electron donor), which shows negative solvatochromism. An intriguing blue shift and enlargement of the fluorescence band upon increasing the solvent polarity have suggested a possible contribution of an upper excited state to the stationary emission. Ultrafast transient absorption has indeed revealed the presence of an intermediate transient species in some solvents. The investigation of the fluorescence properties at low temperatures and in the rigid matrix has given a clear indication of this additional emission at shorter wavelengths. Femtosecond up-conversion measurements have shown interesting rise-decay dynamics in the kinetics and two well distinguished emission bands characterized by different deactivations. A single isoemissive point in the time-resolved area-normalized spectra has unambiguously pointed out the presence of two consecutive emissive species: the locally excited and the intramolecular charge transfer excited states. PMID:25474173

  12. Translation of in vitro to in vivo pyridinium oxime potential in tabun poisoning.

    PubMed

    Katalinić, Maja; Maček Hrvat, Nikolina; Žďárová Karasová, Jana; Misik, Jan; Kovarik, Zrinka

    2015-12-01

    Even if organophosphorus (OP) nerve agents were banned entirely, their presence would remain a problem as weapons of terror (like in Syria). Oxime antidotes currently used in medical practice still fall short of their therapeutic purpose, as they fail to fully restore the activity of cholinesterases, the main target for OPs. As orphan drugs, these antidotes are tested too seldom for anybody's benefit. Over the last few decades, search for improved reactivators has reached new levels, but the translation of data obtained in vitro to in vivo application is still a problem that hinders efficient therapy. In this study, we tested the strengths and weaknesses of extrapolating pyridinium oxime antidotes reactivation efficiency from in vitro to in vivo application. Our results show that this extrapolation is possible with well-determined kinetic constants, but that it also largely depends on oxime circulation time and its tissue-specific distribution. This suggests that pharmacokinetic studies should be planned at the early stages of antidote development. Special attention should also be given to improving oxime distribution throughout the organism to overcome this major constraint in improving overall OP therapy. PMID:26751861

  13. Poly(phenyl sulfone) anion exchange membranes with pyridinium groups for vanadium redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Zhang, Bengui; Zhang, Enlei; Wang, Guosheng; Yu, Ping; Zhao, Qiuxia; Yao, Fangbo

    2015-05-01

    To develop high performance and cost-effective membranes with low permeability of vanadium ions for vanadium redox flow battery (VRFB) application, poly(phenyl sulfone) anion exchange membranes with pyridinium groups (PyPPSU) are prepared and first investigated for VRFB application. PyPPSU membranes show much lower vanadium ions permeability (0.07 × 10-7-0.15 × 10-7 cm2 min-1) than that of Nafion 117 membrane (31.3 × 10-7 cm2 min-1). As a result, the self-discharge duration of the VRFB cell with PyPPSU membrane (418 h) is about four times longer than that of VRFB cell with Nafion 117 membrane (110 h). Furthermore, the VRFB cell with PyPPSU membrane exhibits higher battery efficiency (coulombic efficiency of 97.8% and energy efficiency of 80.2%) compare with that of VRFB cell with Nafion 117 membrane (coulombic efficiency of 96.1% and energy efficiency of 77.2%) at a high current density of 100 mA cm-2. In addition, PyPPSU membrane exhibits stable performance in 100-cycle test. The results indicate that PyPPSU membrane is high performance and low-cost alternative membrane for VRFB application.

  14. Pyridinium crosslinking and collagen types in myocardium and valve are altered in copper deficient swine

    SciTech Connect

    McCormick, R.J.; Vadiamudl, R.K.; Medeiros, D.M.; Failla, M.L. Ohio State Univ., Columbus Dept. of Agriculture, Beltsville, MD )

    1991-03-15

    Weaned pigs were fed semipurified diets with either adequate or deficient Cu for 10 weeks and sacrificed at mean body wt of 49.1 and 45.8 ({minus}Cu) kg. Cu deficient pigs were characterized by decreased plasma and tissue Cu, plasma ceruloplasmin activity and hematocrit, and increased relative heart size. Collagen was extracted from left ventricle (LV) and bicuspid valves (BV) and analyzed for nonreducible collagen crosslink hydroxylsylpyridinoline (HP) by reverse phase HPLC and for type III and type I collagens by peptide mapping in SDS-PAGE after CNBr digestion. The quantity of collagen in LV and BV was not altered by Cu deficiency. However, pyridinium crosslinking was decreased in LV and in BV. Also, the proportion of type III collagen was higher in collagen extracted from LV and BV of Cu deficient pigs. These data show that dietary Cu deficiency reduced the concentration of mature crosslinks in cardiac collagen and was associated with a shift in collagen type to the form characteristic of developing tissues. Such changes in collagen may directly contribute to cardiac abnormalities associated with dietary Cu deficiency.

  15. Disposition of ( UC)methyl bromide in rats after inhalation

    SciTech Connect

    Bond, J.A.; Dutcher, J.S.; Medinsky, M.A.; Henderson, R.F.; Birnbaum, L.S.

    1985-01-01

    The purpose of this investigation was to determine the disposition and metabolism of ( UC)methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol ( UC)methyl bromide/liter air (9.0 ppm, 25C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of UC as UCO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total ( UC)methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the UCO2 being excreted with a half-time of 3.9 +/- 0.1 hr (anti x +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of UC in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of UC. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of UC from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the UC in the tissues was methyl bromide metabolities. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted. 22 references, 4 figures, 4 tables.

  16. Effect of cation type, alkyl chain length, adsorbate size on adsorption kinetics and isotherms of bromide ionic liquids from aqueous solutions onto microporous fabric and granulated activated carbons.

    PubMed

    Hassan, Safia; Duclaux, Laurent; Lévêque, Jean-Marc; Reinert, Laurence; Farooq, Amjad; Yasin, Tariq

    2014-11-01

    The adsorption from aqueous solution of imidazolium, pyrrolidinium and pyridinium based bromide ionic liquids (ILs) having different alkyl chain lengths was investigated on two types of microporous activated carbons: a fabric and a granulated one, well characterized in terms of surface chemistry by "Boehm" titrations and pH of point of zero charge measurements and of porosity by N2 adsorption at 77 K and CO2 adsorption at 273 K. The influence of cation type, alkyl chain length and adsorbate size on the adsorption properties was analyzed by studying kinetics and isotherms of eight different ILs using conductivity measurements. Equilibrium studies were carried out at different temperatures in the range [25-55 °C]. The incorporation of ILs on the AC porosity was studied by N2 adsorption-desorption measurements at 77 K. The experimental adsorption isotherms data showed a good correlation with the Langmuir model. Thermodynamic studies indicated that the adsorption of ILs onto activated carbons was an exothermic process, and that the removal efficiency increased with increase in alkyl chain length, due to the increase in hydrophobicity of long chain ILs cations determined with the evolution of the calculated octanol-water constant (Kow). The negative values of free energies indicated that adsorption of ILs with long chain lengths having hydrophobic cations was more spontaneous at the investigated temperatures. PMID:24929502

  17. UV photodissociation of methyl bromide and methyl bromide cation studied by velocity map imaging

    SciTech Connect

    Blanchet, Valerie; Samartzis, Peter C.; Wodtke, Alec M.

    2009-01-21

    We employ the velocity map imaging technique to measure kinetic energy and angular distributions of state selected CH{sub 3} (v{sub 2}=0,1,2,3) and Br ({sup 2}P{sub 3/2}, {sup 2}P{sub 1/2}) photofragments produced by methyl bromide photolysis at 215.9 nm. These results show unambiguously that the Br and Br* forming channels result in different vibrational excitations of the umbrella mode of the methyl fragment. Low energy structured features appear on the images, which arise from CH{sub 3}Br{sup +} photodissociation near 330 nm. The excess energy of the probe laser photon is channeled into CH{sub 3}{sup +} vibrational excitation, most probably in the {nu}{sub 4} degenerate bend.

  18. Zinc Bromide Combustion: Implications for the Consolidated Incinerator Facility

    SciTech Connect

    Oji, L.N.

    1998-12-16

    In the nuclear industry, zinc bromide (ZnBr2) is used for radiation shielding. At Savannah River Site (SRS) zinc bromide solution, in appropriate configurations and housings, was used mainly for shielding in viewing windows in nuclear reactor and separation areas. Waste stream feeds that will be incinerated at the CIF will occasionally include zinc bromide solution/gel matrices.The CIF air pollution systems control uses a water-quench and steam atomizer scrubber that collects salts, ash and trace metals in the liquid phase. Water is re-circulated in the quench unit until a predetermined amount of suspended solids or dissolved salts are present. After reaching the threshold limit, "dirty liquid", also called "blowdown", is pumped to a storage tank in preparation for treatment and disposal. The air pollution control system is coupled to a HEPA pre-filter/filter unit, which removes particulate matter from the flue gas stream (1).The objective of this report is to review existing literature data on the stability of zinc bromide (ZnBr2) at CIF operating temperatures (>870 degrees C (1600 degrees F) and determine what the combustion products are in the presence of excess air. The partitioning of the combustion products among the quencher/scrubber solution, bottom ash and stack will also be evaluated. In this report, side reactions between zinc bromide and its combustion products with fuel oil were not taken into consideration.

  19. Cross-Coupling of Aromatic Bromides with Allylic Silanolate Salts

    PubMed Central

    Denmark, Scott E; Werner, Nathan S.

    2009-01-01

    The sodium salts of allyldimethylsilanol and 2-butenyldimethylsilanol undergo palladium-catalyzed cross-coupling with a wide variety of aryl bromides to afford allylated and crotylated arenes. The coupling of both silanolates required extensive optimization to deliver the expected products in high yields. The reaction of the allyldimethylsilanolate takes place at 85 °C in DME with allylpalladium chloride dimer (2.5 mol %) to afford 7–95% yields of the allylation products. Both electron-rich and sterically-hindered bromides reacted smoothly, whereas electron-poor bromides cross-coupled in poor yield because of a secondary isomerization to the 1-propenyl isomer (and subsequent polymerization). The 2-butenyldimethylsilanolate (E/Z, 80:20) required additional optimization to maximize the formation of the branched (γ-substitution product). A remarkable influence of added alkenes (dibenzylideneacetone and norbornadiene) led to good selectivities for electron-rich and electron-poor bromides in 4–83% yields. However, bromides containing coordinating groups (particularly in the ortho position) gave lower, and in one case even reversed, selectivity. Configurationally homogeneous E-silanolates gave slightly higher γ-selectivity than the pure Z-silanolates. A unified mechanistic picture involving initial γ-transmetalation followed by direct reductive elimination or σ–π isomerization can rationalize all of the observed trends. PMID:18998687

  20. Effect of Bromide-Hypochlorite Bactericides on Microorganisms1

    PubMed Central

    Shere, Lewis; Kelley, Maurice J.; Richardson, J. Harold

    1962-01-01

    A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% “available chlorine” and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% “available chlorine” and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes, and Proteus vulgaris. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide. PMID:13977149

  1. Electrophysiological study of intravenous pinaverium bromide in cardiology.

    PubMed

    Guerot, C; Khemache, A; Sebbah, J; Noel, B

    1988-01-01

    Pinaverium bromide is a musculotropic spasmolytic agent which acts by inhibiting transmembrane calcium movements, an effect similar to that of verapamil. Because of this, an investigation was carried out to see if it had any electrophysiological effects in patients with various cardiac disorders. In an open study, 10 patients received 2 mg pinaverium bromide intravenously. In a double-blind study, 10 patients received 4 mg pinaverium bromide intravenously and 10 patients placebo. Patients included those with either normal or pathological basal conduction, such as bundle-branch block and 1st degree atrioventricular block. Measurements were made of electrophysiological parameters before and 10 minutes after injection. The results showed that neither of the two doses of pinaverium bromide had any effect on atrial excitability, sino-atrial conduction, node and trunk atrioventricular conduction or on intraventricular conduction. No significant difference was seen in comparison with placebo. Pinaverium bromide had no anti-arrhythmic properties in these studies. Local, cardiac and general clinical tolerability was good in all patients. PMID:3219882

  2. Quantum-chemical study of the mechanism of formation of the pyridinium ion on an aluminosilicate surface and in the liquid phase

    SciTech Connect

    Zhanpeisov, N.U.; Pel'menshchikov, A.G.; Paukshtis, E.A.; Zhidomirov, G.M.

    1987-08-01

    The possibility of a pyridinium ion forming on the surface of an aluminosilicate is considered in terms of the cluster approximation of the MINDO/3-NV method proposed by the authors. The calculations show that in the first stage of absorption of pyridine on Broensted-acid-site (BAC) aluminosilicates, a hydrogen-bonded complex forms which then transforms to a pyridinium ion. The energy required to transfer a proton from the surface to the pyridine is offset by the formation of a number of C-O ..pi..-bonds. A comparison is drawn between the analogous process of the formation of an ion of pyridinium in the liquid phase, which was investigated using Germer's solvation model taking the interaction of pyridine with an aqueous solution of hydrochloric acid as an example.

  3. Two novel organic-inorganic hybrid materials from tetrachloridometallate(II) salts and 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium.

    PubMed

    Campos-Gaxiola, José J; Arredondo Rea, Susana P; Corral Higuera, Ramón; Höpfl, Herbert; Cruz Enríquez, Adriana

    2015-01-01

    Two organic-inorganic hybrid compounds have been prepared by the combination of the 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium cation with perhalometallate anions to give 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium tetrachloridocobaltate(II), (C12H12N2)[CoCl4], (I), and 4-[(E)-2-(pyridin-1-ium-2-yl)ethenyl]pyridinium tetrachloridozincate(II), (C12H12N2)[ZnCl4], (II). The compounds have been structurally characterized by single-crystal X-ray diffraction analysis, showing the formation of a three-dimensional network through X-H...ClnM(-) (X = C, N(+); n = 1, 2; M = Co(II), Zn(II)) hydrogen-bonding interactions and π-π stacking interactions. The title compounds were also characterized by FT-IR spectroscopy and thermogravimetric analysis (TGA). PMID:25567575

  4. Cetyltrimethyl ammonium bromide assisted hydrothermal growth of hematite hollow cubes

    SciTech Connect

    Wang, Wei-Wei; Yao, Jia-Liang

    2010-11-15

    Hematite hollow cubes have been prepared by forced hydrolysis of ferric chloride solutions under hydrothermal conditions. The effects of reaction time, reaction temperature and cetyltrimethyl ammonium bromide on the transformation process from akageneite to hematite were investigated in detail. The products were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. It is found that cetyltrimethyl ammonium bromide was a critical factor influencing the phase transformation process of akageneite and the final morphology of the as-prepared products. With cetyltrimethyl ammonium bromide, hematite hollow cubes and porous spheres were obtained. Otherwise only dense cubes were observed even prolonging reaction time or increasing reaction temperature. The mechanism was proposed.

  5. Self-assembly of [UO2X4]2- (X=Cl, Br) dianions with γ substituted pyridinium cations: Structural systematics and fluorescence properties

    NASA Astrophysics Data System (ADS)

    Surbella, Robert G.; Andrews, Michael B.; Cahill, Christopher L.

    2016-04-01

    Room temperature self-assembly of [UO2X4]2- (X=Cl, Br) with γ substituted pyridinium cations has resulted in the formation of twelve compounds that were studied via single crystal X-ray diffraction and fluorescence spectroscopy. Systematic variation of electron donating groups on the pyridinium species is shown to influence the presence and/or strength of various supramolecular synthons, including hydrogen bonding and pi interactions. Combinations of such non-covalent interactions (NCIs) have given rise to a range of supramolecular assemblies, and are shown to influence uranyl emission by way of second sphere coordination to equatorial ligands.

  6. Syntheses of [omega]-alkynyl aldehydes and ketones via oxidation of [omega]-alkynyl alcohols with pyridinium dichromate

    SciTech Connect

    Bierer, D.E.; Kabalka, G.W. )

    1988-01-01

    Pyridinium dichromate (PDC) is an effective reagent for the oxidation of alcohols and a number of modifications of the original procedure have been reported. Interestingly, PDC has never been used to oxidize non-conjugated acetylenic alcohols. As a part of a project involving the chemical preparation of a number of unsaturated amino acids, the authors investigated the synthesis of a series of [omega]-alkynyl aldehydes. The authors now report that the PDC oxidation of [omega]-alkynyl alcohols is an effective route to the corresponding [omega]-alkynyl carbonyl compounds.

  7. Organocatalyzed One-Step Synthesis of Functionalized N-Alkyl-Pyridinium Salts from Biomass Derived 5-Hydroxymethylfurfural.

    PubMed

    Sowmiah, Subbiah; Veiros, Luís F; Esperança, José M S S; Rebelo, Luís P N; Afonso, Carlos A M

    2015-11-01

    An efficient and scalable method has been developed for the synthesis of N-alkylpyridinium salts from biomass derived 5-hydroxymethylfurfural and alkyl amines using a catalytic amount of formic acid. This protocol is also extended to various diamines providing the exclusive formation of mono-N-alkylpyridinium salts. In addition, the mechanism for the formation of pyridinium salts was studied by DFT and using H2(18)O isotope labeled experiments showing no incorporation of (18)O in the product. PMID:26493742

  8. [Application of the rough sets theory to the analysis of structure-activity relationships of pyridinium antifungal compounds].

    PubMed

    Krysiński, J

    1994-04-01

    Relationships between chemical structure and antifungal activity of 72 quaternary pyridinium chlorides were analysed using the method of rough sets. In the information system the compounds are described by eight condition attributes and divided into three classes of activity. Using the rough sets approach a smallest set of four condition attributes significant for a high quality of classification and accuracy of classes has been found. The resulting decision algorithm describes relations between structure and antifungal activity in terms of significant condition attributes. It may be helpful in predicting structures of new antifungal compounds to be synthesized. PMID:8204024

  9. Eco-Friendly Synthesis of a New Class of Pyridinium-Based Ionic Liquids with Attractive Antimicrobial Activity.

    PubMed

    Messali, Mouslim

    2015-01-01

    The present study reports a green synthesis of a new family of ionic liquids (ILs) based on functionalized 4-dimethylaminopyridinium derivatives. The structures of 23 newly synthesized ILs (2-24) were confirmed by FT-IR, (1)H-, (13)C-, (11)B-, (19)F-, and (31)P-NMR spectroscopy and mass spectrometry. The antimicrobial activity of all novel ILs was tested against a panel of bacteria and fungi. The results prove that all tested ILs are effective antibacterial and antifungal agents, especially 4-(dimethylamino)-1-(4-phenoxybutyl) pyridinium derivatives 5 and 19. PMID:26287148

  10. Oxidation of manganese(II) during chlorination: role of bromide.

    PubMed

    Allard, S; Fouche, L; Dick, J; Heitz, A; von Gunten, U

    2013-08-01

    The oxidation of dissolved manganese(II) (Mn(II)) during chlorination is a relatively slow process which may lead to residual Mn(II) in treated drinking waters. Chemical Mn(II) oxidation is autocatalytic and consists of a homogeneous and a heterogeneous process; the oxidation of Mn(II) is mainly driven by the latter process. This study demonstrates that Mn(II) oxidation during chlorination is enhanced in bromide-containing waters by the formation of reactive bromine species (e.g., HOBr, BrCl, Br2O) from the oxidation of bromide by chlorine. During oxidation of Mn(II) by chlorine in bromide-containing waters, bromide is recycled and acts as a catalyst. For a chlorine dose of 1 mg/L and a bromide level as low as 10 μg/L, the oxidation of Mn(II) by reactive bromine species becomes the main pathway. It was demonstrated that the kinetics of the reaction are dominated by the adsorbed Mn(OH)2 species for both chlorine and bromine at circumneutral pH. Reactive bromine species such as Br2O and BrCl significantly influence the rate of manganese oxidation and may even outweigh the reactivity of HOBr. Reaction orders in [HOBr]tot were found to be 1.33 (±0.15) at pH 7.8 and increased to 1.97 (±0.17) at pH 8.2 consistent with an important contribution of Br2O which is second order in [HOBr]tot. These findings highlight the need to take bromide, and the subsequent reactive bromine species formed upon chlorination, into account to assess Mn(II) removal during water treatment with chlorine. PMID:23859083

  11. Intensification of sonochemical degradation of malachite green by bromide ions.

    PubMed

    Moumeni, Ouarda; Hamdaoui, Oualid

    2012-05-01

    Sonochemical oxidation has been investigated as a viable advanced oxidation process (AOP) for the destruction of various pollutants in water. Ultrasonic irradiation generates ()OH radicals that can recombine, react with other gaseous species present in the cavity, or diffuse out of the bubble into the bulk liquid medium where they are able to react with solute molecules. The extent of degradation of an organic dye such as malachite green (MG) is limited by the quantity of hydroxyl radicals diffused from cavitation bubbles. In this work, the effect of bromide ions on sonolytic degradation of MG was investigated. The obtained results clearly demonstrated the considerable enhancement of sonochemical destruction of MG in the presence of bromide. No significant differences were observed in the presence of chloride and sulfate, excluding the salting-out effect. Positive effect of bromide ions, which increases with increasing bromide level and decreasing MG concentration, is due to the generation of dibromine radical anion (Br(2)(-)) formed by reaction of Br(-) with ()OH radicals followed by rapid complexation with another anion. The generated Br(2)(-) radicals, reactive but less than ()OH, are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for degradation of an organic dye such as MG. Additionally, Br(2)(-) radicals undergo radical-radical recombination at a lesser extent than hydroxyl radicals and would be more available than ()OH for substrate degradation, both at the bubble surface and in the solution bulk. This effect compensates for the lower reactivity of Br(2)(-) compared to ()OH toward organic substrate. Addition of bromide to natural and sea waters induces a slight positive effect on MG degradation. In the absence of bromide, ultrasonic treatment for the removal of MG was promoted in complex matrices such as natural and sea waters. PMID:21911308

  12. Methyl bromide emissions from a covered field: II. Volatilization

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.

    1996-01-01

    An experiment to investigate the environmental fate and transport of methyl bromide in agricultural fields is described. The methyl bromide volatilization rate was determined as a function of time for conditions where methyl bromide was applied at a rate of 843 kg in a 3.5-ha (i.e., 240 kg/ha) field covered with plastic at a depth of 25 cm. Three methods were used to estimate the methyl bromide volatilization rate, including: the aerodynamic, theoretical profile shape and integrated horizontal flux methods. The highest methyl bromide volatilization rates were at the beginning of the experiment. Within the first 24 h, approximately 36% of the applied methyl bromide mass was lost. Diurnally, the largest volatilization rates occurred during the day when temperatures were high and the atmosphere was unstable. Cooler temperatures, light winds, and neutral to stable atmospheric conditions were present at night, reducing the flux. The total emission calculated using these methods was found to be approximately 64% ({+-} 10%) of the applied mass. A mass balance was calculated using each flux estimation technique and several methods for analyzing the data. The average mass recovery using all the flux methods was 867 kg ({+-}83 kg), which was 102.8% ({+-}9.8%) of the applied (i.e., 843 kg). The range in the mass balance percent (i.e., percent of applied mass that is measured) is from 88 to 112%. The averaged mass balance percent for the aerodynamic method, which involved using the measured data directly, was approximately 100.8%. The total emission calculated using the aerodynamic method was found to be approximately 62% ({+-}11%) of the applied mass. 29 refs., 7 figs., 1 tab.

  13. Photochemistry of alkyl bromides trapped in water ice films

    NASA Astrophysics Data System (ADS)

    Schrems, O.; Okaikwei, B.; Bluszcz, Th.

    2012-04-01

    Photochemical reactions of atmospheric trace gases taking place at the surface of atmospheric ice particles and in bulk ice are important in stratospheric and tropospheric chemistry but also in polar and alpine snowpack chemistry. Consequently, the understanding of the uptake und incorporation of atmospheric trace gases in water ice as well as their interactions with water molecules is very important for the understanding of processes which occur in ice particles and at the air/ice interface. Reactive atmospheric trace gases trapped in ice are subject of photochemical reactions when irradiated with solar UV radiation. Among such compounds bromine species are highly interesting due to their potential of depleting ozone both in the stratosphere and troposphere. Organic bromine gases can carry bromine to the stratosphere. Methyl bromide (CH3Br) is the largest bromine carrier to the stratosphere. It has both natural and anthropogenic sources. In this contribution we will present the results of our laboratory studies of alkyl bromides (methyl, bromide (CH3Br), dimethyl bromide (CH2Br2), n-propyl bromide (C3H7Br), 1,2-dibromoethane C2H4Br2)), trapped in water ice. We have simulated the UV photochemistry of these brominated alkanes isolated in ice films kept at 16 K and for comparison in solid argon matrices. The photoproducts formed in the ice have been identified by means of FTIR spectroscopy. Reflection absorption infrared spectroscopy (RAIRS) is especially useful to study nascent ice surfaces, kinetics of adsorption/decomposition, and heterogeneous catalysis. Among the observed photoproducts we could identify carbon monoxide and carbon dioxide for each alkyl bromide studied. The photoproduct HBr is dissociated in the bulk ice. Based on the experimental observations possible reaction mechanisms will be discussed.

  14. Brain levels of the neurotoxic pyridinium metabolite HPP+ and extrapyramidal symptoms in haloperidol-treated mice.

    PubMed

    Crowley, James J; Ashraf-Khorassani, Mehdi; Castagnoli, Neal; Sullivan, Patrick F

    2013-12-01

    The typical antipsychotic haloperidol is a highly effective treatment for schizophrenia but its use is limited by a number of serious, and often irreversible, motor side effects. These adverse drug reactions, termed extrapyramidal syndromes (EPS), result from an unknown pathophysiological mechanism. One theory relates to the observation that the haloperidol metabolite HPP+ (4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]-pyridinium) is structurally similar to MPP+ (1-methyl-4-phenylpyridinium), a neurotoxin responsible for an irreversible neurodegenerative condition similar to Parkinson's disease. To determine whether HPP+ contributes to haloperidol-induced EPS, we measured brain HPP+ and haloperidol levels in strains of mice at high (C57BL/6J and NZO/HILtJ) and low (BALB/cByJ and PWK/PhJ) liability to haloperidol-induced EPS following chronic treatment (7-10 adult male mice per strain). Brain levels of HPP+ and the ratio of HPP+ to haloperidol were not significantly different between the haloperidol-sensitive and haloperidol-resistant strain groups (P=0.50). Within each group, however, strain differences were seen (P<0.01), indicating that genetic variation regulating steady-state HPP+ levels exists. Since the HPP+ levels that we observed in mouse brain overlap the range of those detected in post-mortem human brains following chronic haloperidol treatment, the findings from this study are physiologically relevant to humans. The results suggest that strain differences in steady-state HPP+ levels do not explain sensitivity to haloperidol-induced EPS in the mice we studied. PMID:24107597

  15. CATALYTIC DETOXIFICATION OF NERVE AGENT AND PESTICIDE ORGANOPHOSPHATES BY BUTYRYLCHOLINESTERASE ASSISTED WITH NON-PYRIDINIUM OXIMES

    PubMed Central

    Radić, Zoran; Dale, Trevor; Kovarik, Zrinka; Berend, Suzana; Garcia, Edzna; Zhang, Limin; Amitai, Gabriel; Green, Carol; Radić, Božica; Duggan, Brendan M.; Ajami, Dariush; Rebek, Julius; Taylor, Palmer

    2016-01-01

    SYNOPSIS We present here a comprehensive in vitro, ex vivo and in vivo study on hydrolytic detoxification of nerve agent and pesticide organophosphates (OPs) catalyzed by purified human butyrylcholinesterase (hBChE) in combination with novel non-pyridinium oxime reactivators. We identified 2-trimethylammonio-6-hydroxybenzaldehyde oxime (TAB2OH) as an efficient reactivator of OP-hBChE conjugates formed by the nerve agents, VX and cyclosarin, and the pesticide, paraoxon. It was also functional in reactivation of sarin and tabun inhibited hBChE. A three to five-fold enhancement of in vitro reactivation of VX, cyclosarin and paraoxon inhibited hBChE was observed, when compared to the commonly used N-methylpyridinium aldoxime reactivator, 2PAM. Kinetic analysis showed the enhancement resulted from improved molecular recognition of corresponding OP-hBChE conjugates by TAB2OH. The unique features of TAB2OH stem from an exocyclic quaternary nitrogen and a hydroxyl, both ortho to an oxime group on a benzene ring. pH dependences reveal participation of the hydroxyl (pKa=7.6) forming an additional ionizing nucleophile to potentiate the oxime (pKa=10) at physiological pH. The TAB2OH protective indices in therapy of sarin and paraoxon exposed mice were enhanced by 30% – 60% when they were treated with a combination of TAB2OH and sub-stoichiometric hBChE. These results establish that oxime-assisted catalysis is feasible for OP bioscavenging. PMID:23216060

  16. Reversible phase transition of 2-carboxypyridinium perchlorate-pyridinium-2-carboxylate (1/1).

    PubMed

    Wang, Bi-Qin; Yan, Hai-Biao; Huang, Zheng-Qing; Zhang, Yun-Hua; Sun, Jing

    2015-04-01

    The title salt, C6H6NO2(+)·ClO4(-)·C6H5NO2, was crystallized from an aqueous solution of equimolar quantities of perchloric acid and pyridine-2-carboxylic acid. Differential scanning calorimetry (DSC) measurements show that the compound undergoes a reversible phase transition at about 261.7 K, with a wide heat hysteresis of 21.9 K. The lower-temperature polymorph (denoted LT; T = 223 K) crystallizes in the space group C2/c, while the higher-temperature polymorph (denoted RT; T = 296 K) crystallizes in the space group P2/c. The relationship between these two phases can be described as: 2a(RT) = a(LT); 2b(RT) = b(LT); c(RT) = c(LT). The crystal structure contains an infinite zigzag hydrogen-bonded chain network of 2-carboxypyridinium cations. The most distinct difference between the higher (RT) and lower (LT) temperature phases is the change in dihedral angle between the planes of the carboxylic acid group and the pyridinium ring, which leads to the formation of different ten-membered hydrogen-bonded rings. In the RT phase, both the perchlorate anions and the hydrogen-bonded H atom within the carboxylic acid group are disordered. The disordered H atom is located on a twofold rotation axis. In the LT phase, the asymmetric unit is composed of two 2-carboxypyridinium cations, half an ordered perchlorate anion with ideal tetrahedral geometry and a disordered perchlorate anion. The phase transition is attributable to the order-disorder transition of half of the perchlorate anions. PMID:25836279

  17. Can betaine pyridinium derivatives be used to control the photoejection of cation?

    PubMed

    Aloïse, S; Ruan, Y; Hamdi, I; Tiwari, A K; Buntinx, G; Azarias, C; Perrier, A; Leray, I

    2016-06-01

    Using a combination of advanced DFT/TDDFT calculations together with ultrafast and stationary spectroscopies we have investigated the photochemistry and cationic complexation ability of 1-pyridinio-benzimidazolate (PyB) and analogs substituted by 15-aza-5-crown (PyB-Aza) or dimethyl-amino groups (PyB-DiMe). Focusing on PyB-Aza, the first aim was to assess the competitive complexation of the imidazole bridge vs. the macrocycle. In acetonitrile, it was found by absorption and emission that the imidazole moiety binds efficiently through lateral electrostatic interaction of high charge density cations and especially Ca(2+) to form a 1 : 1, metal : ligand (M : L) complex. Modulation of the complexation toward para substitution of the phenyl ring with a donor group is reported with values ranging from log K = 3.4 to 6.8. Complexation values are properly predicted by DFT calculations. From a photochemical point of view, for the same series, the trend is parallel to the rate of the photo-release process, found to be less than 200 femtosecond (fs), the fastest photorelease characteristic time reported so far. Unlike photoinduced charge transfer molecules linked with an aza-crown group, the mechanism appears simpler with no participation of loose complexes due to the macrocavity effect. Relaxation mechanisms after cation ejection are discussed as well. Finally, even if any photoinduced translocation of cation is reported for the PyB-Aza molecule between two complexation sites, a discussion about the use of betaine pyridinium as a molecular tool for the smart manipulation of cation systems is initiated. PMID:27212223

  18. 2-Pyridinium propanol hydrogen squarate: experimental and computational study of a nonlinear optical material.

    PubMed

    Korkmaz, Ufuk; Bulut, Ahmet

    2015-02-01

    The experimental and theoretical investigation of a novel organic nonlinear optical (NLO) squarate salt of 2-pyridinium propanol hydrogen squarate (1), C8H12ON(+)·C4HO4(-), were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P-1 space group. In the asymmetric unit each squaric acid molecules have donated one H atom to the pyridines N1 and N2 atoms of a 2-pyridine propanol molecule, forming the salt (1). The X-ray analysis clearly indicated that the crystal packing has shown the hydrogen bonding ring pattern of D2(2)(10) (α-dimer) through N-H⋯O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the X-ray analysis result. The molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained. PMID:25459503

  19. 2-Pyridinium propanol hydrogen squarate: Experimental and computational study of a nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Korkmaz, Ufuk; Bulut, Ahmet

    2015-02-01

    The experimental and theoretical investigation of a novel organic nonlinear optical (NLO) squarate salt of 2-pyridinium propanol hydrogen squarate (1), C8H12ON+ ·C4HO4-, were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P-1 space group. In the asymmetric unit each squaric acid molecules have donated one H atom to the pyridines N1 and N2 atoms of a 2-pyridine propanol molecule, forming the salt (1). The X-ray analysis clearly indicated that the crystal packing has shown the hydrogen bonding ring pattern of D22 (10) (α-dimer) through Nsbnd H⋯O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the X-ray analysis result. The molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.

  20. Interaction of pyridinium bis-retinoid (A2E) with bilayer lipid membranes.

    PubMed

    Sokolov, V S; Sokolenko, E A; Sokolov, A V; Dontsov, A E; Chizmadzhev, Y A; Ostrovsky, M A

    2007-02-01

    The accumulation of lipofuscin granules within the retinal pigment epithelium (RPE) cells is correlated with the progression of age-related macular degeneration. One of the fluorophores contained in lipofiscin granules is pyridinium bis-retinoid (A2E). To test its membrane-toxic effect, the interaction of A2E with bilayer lipid membranes (BLM) was studied. The incorporation of charged A2E molecules into the membranes has been detected as a change of either zeta-potential of multilayer liposomes or boundary potential of BLM. It was shown that the presence of up to 25mol% of A2E did not destabilize the bilayers made of saturated phosphatidylcholine (PC). However, the destabilizing effect became very significant when BLM contained negatively charged lipids such as cardiolipin or phosphatidylserine. The electrical breakdown measurements revealed that the A2E-induced decrease of BLM stability was primarily associated with the growing probability of lipid pore formation. It was found from the measurements of boundary potential of BLM that exposure of A2E to light initiates its transformation into at least two products. One of them is epoxy-A2E, which, being hydrophilic, moves from the membrane into water solution. The other product is a non-identified hydrophobic substance. Illumination of A2E-containing BLM made from unsaturated PC by visible light caused the membrane damage presumably due to oxidation of these lipids by singlet oxygen generated by excited A2E molecules. However, this effect was very weak compared to the effect of known photosensitizers. The illumination of BLM with A2E also leads to the damage of gramicidin incorporated into the membrane, as was detected by measuring the conductance of channels formed by this peptide. PMID:17070694

  1. Versatile Route to Arylated Fluoroalkyl Bromide Building Blocks.

    PubMed

    Kaplan, Peter T; Vicic, David A

    2016-02-19

    New difunctionalized and fluoroalkylated silyl reagents have been prepared that react with silver and copper salts to afford active catalysts that can be used to synthesize arylated fluoroalkyl bromide building blocks. It has been shown that the [(phen)Ag(CF2)nBr] intermediates are capable of transferring both the phenanthroline ligand and the fluoroalkyl bromide chain to copper iodide, eliminating the need for a preligated copper salt precursor. The methodology is compatible with various chain lengths of the fluoroalkyl halide functionality. PMID:26820388

  2. Investigation of possible interaction between pinaverium bromide and digoxin.

    PubMed

    Weitzel, O; Seidel, G; Engelbert, S; Berksoy, M; Eberhardt, G; Bode, R

    1983-01-01

    A single-blind study was carried out in 25 patients, who were receiving maintenance therapy for congestive heart failure with digoxin, to investigate the effect on steady-state plasma digoxin levels of concomitant administration of the spasmolytic, pinaverium bromide (50 mg 3-times daily). Patients received pinaverium bromide for 12 days followed by placebo for a further 7 days. Assessment of the results in 21 patients showed no evidence of any statistically significant variations in plasma digoxin levels during either treatment period or in the clinical observations which might indicate drug interaction. PMID:6653138

  3. Action of pinaverium bromide on calmodulin-regulated functions.

    PubMed

    Wuytack, F; De Schutter, G; Casteels, R

    1985-08-01

    Pinaverium bromide at concentrations below 10(-5) M did not inhibit calmodulin-dependent enzymes such as phosphodiesterase and the Ca transport ATPase of the plasma membrane. At higher concentrations the compound interacted with the stimulation of those enzymes by calmodulin and also inhibited the calmodulin-independent activity. A similar inhibitory action was observed for the NaK ATPase. It is concluded that the inhibitory action of pinaverium bromide on smooth muscle concentration at concentrations below 10(-5) M was due to its interaction with the voltage-dependent Ca channels and not to its interference with the calmodulin-dependent activation of the contractile proteins. PMID:2995077

  4. Magnesium Lewis Acid Assisted Oxidative Bromoetherification Involving Bromine Transfer from Alkyl Bromides with Aldehydes by Umpolung of Bromide.

    PubMed

    Moriyama, Katsuhiko; Nishinohara, Chihiro; Togo, Hideo

    2016-08-16

    An oxidative bromoetherification involving a bromine transfer from alkyl bromides upon reacting them with aldehydes in a Grignard reaction with a concurrent oxidation of bromide was developed to provide substituted tetrahydrofurans in high yields. This reaction, which proceeds through two types of bromine transfer, was promoted by the addition of a Brønsted acid. Mechanistic studies suggested that a magnesium Lewis acid activates hypobromate, which is generated in situ from the reaction of bromide and Oxone to improve the electrophilicity of the bromonium ion (Br(+) ) for the oxidative bromoetherification of alkenyl alcohols. Furthermore, the magnesium Lewis acid catalyzed oxidative bromoetherification of an alkenyl alcohol proceeded to provide a cyclization product in 92 % yield. PMID:27304660

  5. Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Alkyl Bromides: Et3N as the Terminal Reductant.

    PubMed

    Duan, Zhengli; Li, Wu; Lei, Aiwen

    2016-08-19

    Reductive cross-coupling has emerged as a direct method for the construction of carbon-carbon bonds. Most cobalt-, nickel-, and palladium-catalyzed reductive cross-coupling reactions to date are limited to stoichiometric Mn(0) or Zn(0) as the reductant. One nickel-catalyzed cross-coupling paradigm using Et3N as the terminal reductant is reported. By using this photoredox catalysis and nickel catalysis approach, a direct Csp(2)-Csp(3) reductive cross-coupling of aryl bromides with alkyl bromides is achieved under mild conditions without stoichiometric metal reductants. PMID:27472556

  6. Crystal structure of bis-[4-(di-methyl-amino)-pyridinium] aqua-bis-(oxalato)oxidovanadate(IV) dihydrate.

    PubMed

    Sehimi, Hiba; Chérif, Ichraf; Zid, Mohamed Faouzi

    2016-07-01

    The title organic-inorganic hybrid salt, (C7H11N2)2[V(C2O4)2O(H2O)]·2H2O, shows a distorted octa-hedral coordination environment for the vanadium(IV) atom in the anion (point group symmetry 2), with four O atoms from two symmetry-related chelating oxalate dianions and two O atoms in trans configuration from a coordinating water mol-ecule and a terminal vanadyl O atom. In the crystal, (001) layers of cations and anions alternate along [001]. The anionic layers are built up by inter-molecular O-H⋯O hydrogen bonds involving the coordinating and solvent water mol-ecules. The cationic layers are linked to the anionic layers via N-H⋯O hydrogen bonds between the pyridinium group and the non-coordinating O atoms of the oxalate group. The 4-(di-methyl-amino)-pyridinium cations are also engaged in π-π stacking with their anti-parallel neighbours [centroid-to-centroid distance = 3.686 (2) Å]. Considering all supra-molecular features, a three-dimensional network structure is accomplished. PMID:27555950

  7. Disiloxanes and Functionalized Silica Gels: One Route, Two Complementary Outcomes-Guanidinium and Pyridinium Ion-Exchangers.

    PubMed

    Tabisz, Łukasz; Tukibayeva, Ainur; Pankiewicz, Radoslaw; Dobielska, Marta; Leska, Boguslawa

    2015-01-01

    Five novel disiloxane compounds comprising guanidinium and pyridinium moieties were obtained with high yields and purity. The verified synthetic pathways were then applied for modification of pre-functionalized silica gel, producing materials with the analogous organic side-chains. These halide-containing compounds and materials were then compared as to their ion-exchange properties: two disiloxanes proved to be effective in leaching different anions (nitrate, benzoate and ascorbate) from solid to organic phase, and pyridinium-functionalized silica gels showed selectivity towards perchlorate ion, removing it from methanolic solutions with preference to other singly charged anions. The results presented demonstrate that both compounds and materials containing silicon-carbon bonds can be produced using the same methodology, but offer strikingly different application opportunities. Comparison of their properties provides additional insight into the binding mode of different anions and hints at how the transition from a flexible siloxane bridge to immobilization on solid surface influences anion-binding selectivity. Additionally, one of the siloxane dipodands was found to form a crystalline and poorly soluble nitrate salt (1.316 g/L, water), although it was miscible with a wide range of solvents as a hydrochloride. A possible explanation is given with the help of semi-empirical calculations. A simple, time- and cost-efficient automated potentiometric titration methodology was used as a viable analytical tool for studying ion-exchange processes for both compounds and materials, in addition to standard NMR, FT-IR and ESI-MS methods. PMID:26714187

  8. Disiloxanes and Functionalized Silica Gels: One Route, Two Complementary Outcomes—Guanidinium and Pyridinium Ion-Exchangers

    PubMed Central

    Tabisz, Łukasz

    2015-01-01

    Five novel disiloxane compounds comprising guanidinium and pyridinium moieties were obtained with high yields and purity. The verified synthetic pathways were then applied for modification of pre-functionalized silica gel, producing materials with the analogous organic side-chains. These halide-containing compounds and materials were then compared as to their ion-exchange properties: two disiloxanes proved to be effective in leaching different anions (nitrate, benzoate and ascorbate) from solid to organic phase, and pyridinium-functionalized silica gels showed selectivity towards perchlorate ion, removing it from methanolic solutions with preference to other singly charged anions. The results presented demonstrate that both compounds and materials containing silicon-carbon bonds can be produced using the same methodology, but offer strikingly different application opportunities. Comparison of their properties provides additional insight into the binding mode of different anions and hints at how the transition from a flexible siloxane bridge to immobilization on solid surface influences anion-binding selectivity. Additionally, one of the siloxane dipodands was found to form a crystalline and poorly soluble nitrate salt (1.316 g/L, water), although it was miscible with a wide range of solvents as a hydrochloride. A possible explanation is given with the help of semi-empirical calculations. A simple, time- and cost-efficient automated potentiometric titration methodology was used as a viable analytical tool for studying ion-exchange processes for both compounds and materials, in addition to standard NMR, FT-IR and ESI-MS methods. PMID:26714187

  9. Synthesis and characterization of an ionic conjugated polymer: poly[2-ethynyl-N-(2-furoyl)pyridinium chloride].

    PubMed

    Gal, Yeong-Soon; Jin, Sung-Ho; Park, Jong Wook

    2014-08-01

    A new ionic polyacetylene derivative with furoyl substituents was prepared by the uncatalyzed polymerization of 2-ethynylpyridine by using 2-furoyl chloride in high yield. The polymer structure was characterized by such instrumental methods as NMR, IR, and UV-visible spectroscopies to have a polyacetylene backbone system with the N-(2-furoyl)pyridinium chloride. The electro-optical and electrochemical properties of poly[2-ethynyl-N-(2-furoyl)pyridinium chloride [PEFPC] were studied. The photoluminescence spectrum showed that the PL peak is at 578 nm corresponding to the photon energy of 2.15 eV. The cyclovoltammograms of PEFPC exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of redox process is controlled by the reactant diffusion process from the oxidation current density of PEFPC versus the scan rates. PMID:25936097

  10. Distribution and quantification of pyridinium cross-links of collagen within the different maturational zones of the chick growth plate.

    PubMed

    Farquharson, C; Duncan, A; Seawright, E; Whitehead, C C; Robins, S P

    1996-08-13

    In order to assess alterations in the collagen network during endochondral ossification the pyridinium cross-links of collagen were quantified in sequential transverse sections through the chick growth plate. This was accomplished using both morphological (alkaline phosphatase (ALP) histochemistry and collagen type X immunostaining) and analytical (HPLC) analyses. In articular cartilage, pyridinoline concentrations were maximal in the deep mature zones. In contrast, the proliferating chondrocyte zone of the growth plate had approximately a 10-fold greater pyridinoline cross-link concentration than the mature hypertrophic zone. Deoxypyridinoline was first found in the prehypertrophic zone of the growth plate cartilage that reacted positively for ALP activity but before collagen type X was detected. However, deoxypyridinoline concentrations were highest in the most differentiated regions of the growth plate where it was the principal pyridinium cross-link. In tibial dyschondroplasia, where chondrocyte differentiation is arrested in the prehypertrophic zone, higher concentrations of both cross-links were found with increasing distance down the lesion. We conclude that the decrease in pyridinoline cross-link concentration down the growth plate may be an essential adaptation (via increased collagenase activity and collagen turnover) of the matrix for vascular invasion and osteoclastic resorption to occur. PMID:8765127

  11. Structural effects of the β-vinyl linker in pyridinium porphyrins: spectroscopic studies in organic solvents and AOT reverse micelles.

    PubMed

    Vaz Serra, Vanda; Andrade, Suzana M; Silva, Eduarda M P; Silva, Artur M S; Neves, Maria G P M S; Costa, Sílvia M B

    2013-12-01

    Two isomeric β-vinylpyridinium porphyrins, 2-[2-(2-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (1, ortho isomer) and 2-[2-(4-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (2, para isomer), which have shown different photodynamic behavior were investigated in organic solvents and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. In organic systems, the absorption spectra present a red-shifted band that is more intense in the para isomer, in addition to the usual Soret band. This new band presents interesting solvatochromic effects which obey the multiparametric Kamlet-Taft equation. In AOT reverse micelles, the ortho isomer exhibits a strong dependence with the parameter ω0 = [H2O]/[AOT] which indicates that the molecule resides at the interface toward the organic phase. By contrast, no evidence was detected for the encapsulation of para isomer 2 in AOT reverse micelles. The hypothesis of two ground state isomers with different contributions of trans and quinoid structures is advanced on the basis of the overall data collected from electronic absorption, steady-state, and transient-state fluorescence emission. A charge transfer state in which an electron is fully transferred from the porphyrin to the pyridinium moiety is associated to a quinoid structure in isomer 2. The trans/quinoid relative proportions may be accounted for by the orientation of the ortho-/para-pyridinium isomers relatively to the porphyrin core. PMID:24175940

  12. Methyl Bromide Alternatives for Floriculture Production in a Problem Site

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Successful methyl bromide alternatives must manage a variety of pest problems in floriculture and vegetable production systems including weeds, plant-parasitic nematodes, and soil-borne diseases. Methods that may be successful in some situations may be challenged in sites with unusually heavy pest p...

  13. EFFECT OF BROMIDE ION ON FORMATION OF HAAS DURING CHLORINATION

    EPA Science Inventory

    loacetic acids (HAAs) during chlorination and he effects of independent variables, including pH, reaction time, and chlorine dosage. Almost all of the indpendent loaetic acids (HAAs) during chlorin...designed to statistically evaluate the influence of bromide ion on the formatio...

  14. Methyl bromide alternatives for postharvest insect disinfestation of California walnuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Before shipment, California inshell walnuts destined for the valuable export market must be disinfested of both field pests (codling moth and navel orangeworm) and common storage pests (Indianmeal moth and red flour beetle). Until recently fumigation with methyl bromide has been the most common dis...

  15. A COMPARISON OF BROMIDE AND NITRATE TRANSPORT IN SOILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sandy soils (with sand content 95-98%) are used for agricultural production, which require careful management of water, chemicals, and nutrients to minimize leaching below the rooting zone. Bromide is used as an indicator of downward transport of soluble nutrients in soils. A leching column study ...

  16. HEALTH AND ENVIRONMENTAL EFFECTS PROFILE FOR METHYL BROMIDE

    EPA Science Inventory

    The Health and Environmental Effects Profile for Methyl Bromide was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency a...

  17. Nickel-Catalyzed Reductive Amidation of Unactivated Alkyl Bromides.

    PubMed

    Serrano, Eloisa; Martin, Ruben

    2016-09-01

    A user-friendly, nickel-catalyzed reductive amidation of unactivated primary, secondary, and tertiary alkyl bromides with isocyanates is described. This catalytic strategy offers an efficient synthesis of a wide range of aliphatic amides under mild conditions and with an excellent chemoselectivity profile while avoiding the use of stoichiometric and sensitive organometallic reagents. PMID:27357076

  18. Reactive films for mitigating methyl bromide emissions from fumigated soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emissions of methyl bromide (MeBr) from agricultural fumigation can lead to depletion of the stratospheric ozone layer, and so its use is being phased out. However, as MeBr is still widely used under Critical Use Exemptions, strategies are still required to control such emissions. In this work, nove...

  19. Calla lily production with methyl bromide alternatives – Year 2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cut flower and ornamental bulb industries rely heavily on a methyl bromide/chloropicrin (MB/Pic) mixture as a key pest management tool. The loss of MB will seriously affect the cut flower and bulb industry, and, in the future, will require growers to use alternative fumigants. Past experiments have...

  20. Depleting methyl bromide residues in soil by reaction with bases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite generally being considered the most effective soil fumigant, methyl bromide (MeBr) use is being phased out because its emissions from soil can lead to stratospheric ozone depletion. However, a large amount is still currently used due to Critical Use Exemptions. As strategies for reducing the...

  1. Methyl bromide alternatives for postharvest insect disinfestation of California walnuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Before shipment, California inshell walnuts destined for the valuable export market must be disinfested of both field pests (codling moth and navel orangeworm) and common storage pests (Indianmeal moth and red flour beetle). Until recently fumigation with methyl bromide has been the most common disi...

  2. The Fate of Alternative Soil Funigants to Methyl Bromide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation is an important agricultural practice for the control of soil-borne pests. Since the phase–out of methyl bromide, due to its role in the depletion of stratospheric ozone, several alternatives such as 1,3-dichloropropene (1,3-D), chloropicrin (CP), and dimethyl disulfide (DMDS) are b...

  3. Status of Alternatives for Methyl Bromide in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide is a fumigant used for disinfestation of soils, commodities and structures. Listed as an ozone-depleting chemical international environmental protocols and the U.S. Clean Air Act require that its use be severely restricted. Although use of this fumigant has fallen considerably, the U....

  4. Weed Control with Methyl Bromide Alternatives: A Review.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide (MeBr) has been used for several decades for pre-plant soil fumigation in high value agricultural and horticultural crops because it can provide broad-spectrum control of insects, nematodes, pathogens, and weeds. However, MeBr has been identified as a powerful ozone-depleting chemica...

  5. Methyl bromide phase out could affect future reforestation efforts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide has long been an integral component in producing healthy tree seedlings in forest nurseries of California, Idaho, Montana, Oregon and Washington. The fumigant was supposed to be completely phased out of use in the United States of America by 2005, but many forest nurseries continue to...

  6. REVIEW OF CONTROL OPTIONS FOR METHYL BROMIDE IN COMMODITY TREATMENT

    EPA Science Inventory

    The report describes recent developments in the control of methyl bromide (MeBr) and discusses technical considerations and requirements for and economic feasibility of recovery. (NOTE: MeBr, fumigant for agricultural commodities, is an ozone depleting chemical. The U.S. EPA has ...

  7. Investigation of bromide's spectra by high resolution UV-laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Ma, Jian-guo

    2011-12-01

    Experimental investigation has been carried out for dissociation/ionisation of methyl bromide using time of flight mass spectrometer, then, the mass signals were assigned to H+, CHm+ (m= 0-3), iBr+ (i = 79, 81), and the main processes of multi-photon ionization and dissociation of CH3Br were given.

  8. PHYTOREMEDIATON POTENTIALS OF SELECTED TROPICAL PLANTS FOR ETHIDIUM BROMIDE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research and development has its own benefits and inconveniences. One of the inconveniences is the generation of enormous quantity of diverse toxic and hazardous wastes and its eventual contamination to soil and groundwater resources. Ethidium bromide (EtBr) is one of the commonly used substances i...

  9. BROMIDE-OXIDANT INTERACTIONS AND THM (TRIHALOMETHANE) FORMATION: A LITERATURE REVIEW

    EPA Science Inventory

    The review focuses on the interactions, not only of bromide and chlorine, but also of bromide and two common oxidation alternatives to chlorine--chlorine dioxide and monochloramine. The data evaluations include discussions of reaction products, potentials for trihalomethane (THM)...

  10. T-type Ca2+ channel modulation by otilonium bromide

    PubMed Central

    Strege, Peter R.; Sha, Lei; Beyder, Arthur; Bernard, Cheryl E.; Perez-Reyes, Edward; Evangelista, Stefano; Gibbons, Simon J.; Szurszewski, Joseph H.

    2010-01-01

    Antispasmodics are used clinically to treat a variety of gastrointestinal disorders by inhibition of smooth muscle contraction. The main pathway for smooth muscle Ca2+ entry is through L-type channels; however, there is increasing evidence that T-type Ca2+ channels also play a role in regulating contractility. Otilonium bromide, an antispasmodic, has previously been shown to inhibit L-type Ca2+ channels and colonic contractile activity. The objective of this study was to determine whether otilonium bromide also inhibits T-type Ca2+ channels. Whole cell currents were recorded by patch-clamp technique from HEK293 cells transfected with cDNAs encoding the T-type Ca2+ channels, CaV3.1 (α1G), CaV3.2 (α1H), or CaV3.3 (α1I) alpha subunits. Extracellular solution was exchanged with otilonium bromide (10−8 to 10−5 M). Otilonium bromide reversibly blocked all T-type Ca2+ channels with a significantly greater affinity for CaV3.3 than CaV3.1 or CaV3.2. Additionally, the drug slowed inactivation in CaV3.1 and CaV3.3. Inhibition of T-type Ca2+ channels may contribute to inhibition of contractility by otilonium bromide. This may represent a new mechanism of action for antispasmodics and may contribute to the observed increased clinical effectiveness of antispasmodics compared with selective L-type Ca2+ channel blockers. PMID:20203058

  11. Acid/base controllable complexation of a triptycene-derived macrotricyclic host and protonated 4,4'-bipyridinium/pyridinium salts.

    PubMed

    Han, Ying; Meng, Zheng; Chen, Chuan-Feng

    2016-01-11

    A new acid/base controllable host-guest system based on a triptycene-derived macrotricyclic host and protonated 4,4'-bipyridinium/pyridinium salts was developed. Moreover, the competition complexation process between the host and two different kinds of 4,4'-bipyridinium salts could also be chemically controlled by acid and base. PMID:26548779

  12. (1-Butyl-4-methyl-pyridinium)[Cu(SCN)2]: a coordination polymer and ionic liquid.

    PubMed

    Spielberg, Eike T; Edengeiser, Eugen; Mallick, Bert; Havenith, Martina; Mudring, Anja-Verena

    2014-04-25

    The compound (C4C1py)[Cu(SCN)2], (C4C1py = 1-Butyl-4-methyl-pyridinium), which can be obtained from CuSCN and the ionic liquid (C4C1py)(SCN), turns out to be a new organic-inorganic hybrid material as it qualifies both, as a coordination polymer and an ionic liquid. It features linked [Cu(SCN)2](-) units, in which the thiocyanates bridge the copper ions in a μ1,3-fashion. The resulting one-dimensional chains run along the a axis, separated by the C4C1py counterions. Powder X-ray diffraction not only confirms the single-crystal X-ray structure solution but proves the reformation of the coordination polymer from an isotropic melt. However, the materials shows a complex thermal behavior often encountered for ionic liquids such as a strong tendency to form a supercooled melt. At a relatively high cooling rate, glass formation is observed. When heating this melt in differential scanning calorimetry (DSC) and temperature-dependent polarizing optical microscopy (POM), investigations reveal the existence of a less thermodynamically stable crystalline polymorph. Raman measurements conducted at 10 and 100 °C point towards the formation of polyanionic chain fragments in the melt. Solid-state UV/Vis spectroscopy shows a broad absorption band around 18,870 cm(-1) (530 nm) and another strong one below 20,000 cm(-1) (<500 nm). The latter is attributed to the d(Cu(I))→π*(SCN)-MLCT (metal-to-ligand charge transfer) transition within the coordination polymer yielding an energy gap of 2.4 eV. At room temperature and upon irradiation with UV light, the material shows a weak fluorescence band at 15,870 cm(-1) (630 nm) with a quantum efficiency of 0.90(2) % and a lifetime of 131(2) ns. Upon lowering the temperature, the luminescence intensity strongly increases. Simultaneously, the band around 450 nm in the excitation spectrum decreases. PMID:24644064

  13. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  14. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  15. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  16. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  17. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  18. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  19. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  20. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  1. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  2. Lithium bromide absorption chiller passes gas conditioning field test

    SciTech Connect

    Lane, M.J.; Huey, M.A.

    1995-07-31

    A lithium bromide absorption chiller has been successfully used to provide refrigeration for field conditioning of natural gas. The intent of the study was to identify a process that could provide a moderate level of refrigeration necessary to meet the quality restrictions required by natural-gas transmission companies, minimize the initial investment risk, and reduce operating expenses. The technology in the test proved comparatively less expensive to operate than a propane refrigeration plant. Volatile product prices and changes in natural-gas transmission requirements have created the need for an alternative to conventional methods of natural-gas processing. The paper describes the problems with the accumulation of condensed liquids in pipelines, gas conditioning, the lithium bromide absorption cycle, economics, performance, and operating and maintenance costs.

  3. Aluminium Electroplating on Steel from a Fused Bromide Electrolyte

    SciTech Connect

    Prabhat Tripathy; Laura Wurth; Eric Dufek; Toni Y. Gutknecht; Natalie Gese; Paula Hahn; Steven Frank; Guy Fredrickson; J Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr-KBr-CsBr-AlBr3) was used to electro-coat aluminium on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminium coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminium coverage. Both salt immersion and open circuit potential measurement suggest that the coatings did display good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminium coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminium coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  4. Aluminum electroplating on steel from a fused bromide electrolyte

    SciTech Connect

    Prabhat K. Tripathy; Laura A. Wurth; Eric J. Dufek; Toni Y. Gutknecht; Natalie J. Gese; Paula Hahn; Steven M. Frank; Guy L. Frederickson; J. Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr–KBr–CsBr–AlBr3) was used to electro-coat aluminum on steel substrates. The electrolytewas prepared by the addition of AlBr3 into the eutectic LiBr–KBr–CsBr melt. A smooth, thick, adherent and shiny aluminum coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminum coverage. Both salt immersion and open circuit potential measurement suggested that the coatings did display a good corrosionresistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminum coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminumcoating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  5. A novel and robust conditioning lesion induced by ethidium bromide

    PubMed Central

    Hollis, Edmund R; Ishiko, Nao; Tolentino, Kristine; Doherty, Ernest; Rodriguez, Maria J.; Calcutt, Nigel A.; Zou, Yimin

    2015-01-01

    Molecular and cellular mechanisms underlying the peripheral conditioning lesion remain unsolved. We show here that injection of a chemical demyelinating agent, ethidium bromide, into the sciatic nerve induces a similar set of regeneration-associated genes and promotes a 2.7-fold greater extent of sensory axon regeneration in the spinal cord than sciatic nerve crush. We found that more severe peripheral demyelination correlates with more severe functional and electrophysiological deficits, but more robust central regeneration. Ethidium bromide injection does not activate macrophages at the demyelinated sciatic nerve site, as observed after nerve crush, but briefly activates macrophages in the dorsal root ganglion. This study provides a new method for investigating the underlying mechanisms of the conditioning response and suggests that loss of the peripheral myelin may be a major signal to change the intrinsic growth state of adult sensory neurons and promote regeneration. PMID:25541322

  6. Viscosity and density of some lower alkyl chlorides and bromides

    SciTech Connect

    Rutherford, W.M.

    1988-07-01

    A high-pressure capillary viscometer, used previously to measure the viscosity of methyl chloride was rebuilt to eliminate the first-order dependence of the measured viscosity on the value assumed for the density of the fluid being investigated. At the same time, the system was arranged so that part of the apparatus could be used to measure density by a volumetric displacement technique. Viscosity and density were measured for ethyl chloride, 1-chloropropane, 1-chlorobutane, methyl bromide, ethyl bromide, and 1-bromopropane. The temperature and pressure ranges of the experiments were 20-150 /sup 0/C and 0.27-6.99 MPa, respectively. The accuracy of the viscosity measurements was estimated to be +-1% and of the density measurements, +-0.2%.

  7. [The use of syntropium bromide as an antispasmodic].

    PubMed

    Galeone, M; Cacioli, D; Moise, G; Bossi, M; Benazzi, E; Monti, G

    1985-09-22

    The following trials were carried out to evaluate the antispasmodic effect of sintropium bromide in a group of 30 patients. The antispasmodic effect on the gastroduodenal system was observed endoscopically. The results were compared by means of double blind tests carried out using placebo and rociverine. The effect in a group of 10 patients was examined by X-ray of the digestive tract. The effect on another group of 20 patients suffering from abdominal colic was clinically evaluated. Sintropium bromide has a prompt anticholinergic action and for this reason may be used in the treatment of painful conditions of the bile, gastro-enteric and renal tracts, and also during the course of endoscopic examinations. PMID:3900811

  8. Oceanic Uptake of Methyl Bromide: Implications for Oceanic Production

    NASA Astrophysics Data System (ADS)

    Yvon-Lewis, S. A.; Butler, J. H.; King, D. B.; Saltzman, E. S.; Tokarczyk, R.

    2002-12-01

    Methyl bromide (CH3Br) is a source of inorganic bromine (Br) in the stratosphere, where it contributes to the depletion of stratospheric ozone. Unlike the chlorofluorocarbons, which are entirely anthropogenic, methyl bromide has both natural and anthropogenic sources. At ~10 parts per trillion in the troposphere, methyl bromide is believed to be the single largest contributor of stratospheric Br. Once in the stratosphere, Br is approximately 50 times more effective in depleting stratospheric ozone than Cl. However, the budget for CH3Br remains largely unbalanced with known sinks outweighing sources by ~50%. With production and degradation occurring in the ocean, the ocean is both a source and a sink for CH3Br. The balance between production and degradation results in the net undersaturation of CH3Br that has been observed over much of the world's ocean with an estimated global net ocean sink ranging from -11 to -20 Gg/y [King et al., 2000 and references therein]. However, effects of climate change, such as changes in windspeed distribution or sea-surface temperature could alter this balance. Modeling the potential effect of such forcing on the net flux of this important trace gas requires an understanding of the factors controlling the distributions of production and degradation in the surface ocean. During three recent research cruises (North Atlantic, North Pacific, and Southern Ocean), CH3Br degradation rate constants were measured along with saturation anomalies. Here we incorporate these data into a gridded global box model to examine the distribution of oceanic production rates necessary to support the observations. King, D.B., J.H. Butler, S.A. Montzka, S.A. Yvon-Lewis, and J.W. Elkins, Implications of methyl bromide supersaturations in the temperate North Atlantic Ocean, J. of Geophys. Res., 105 (D15), 19763-19769, 2000.

  9. Problems with NIOSH method 2520 for methyl bromide

    SciTech Connect

    Tharr, D.

    1994-03-01

    The National Institute for Occupational Safety and Health (NIOSH) publishes the NIOSH Manual of Analytical Methods (NMAM), a collection of analytical methods for characterizing exposures to environmental chemicals. When an industrial hygienist selects a method to monitor worker exposure, it is important to remember that not all the methods in the NMAM have undergone the same level of evaluation, as the following case demonstrates. As part of an industrywide study of the health effects resulting from methyl bromide exposure in structural and agricultural applicators, NIOSH researchers conducted industrial hygiene monitoring for methyl bromide in Florida during July 1990. NIOSH method 2520 was used. This method recommends use of two charcoal tubes (400 mg/100 mg) in series, desorption with carbon disulfide, and analysis by gas chromatography with a flame ionization detector. Sampling results from these surveys indicated a capacity problem. A project was then initiated to determine the reason for the methyl bromide breakthrough that occurred during industrial hygiene monitoring. While conducting research to define and solve this problem, several other problems were identified: reduced adsorption capacity caused by high humidity, difficulty in preparing standard solutions, sample instability, change in recovery with loading, and insufficiently low quantitation limit. The addition of a drying tube to the sampling train, as well as changes to the analytical technique, to the desorption solvent, and to the time till analysis, resulted in an improved method for methyl bromide. This case study demonstrates the importance of noting the conditions under which a method was evaluated and the benefit of testing method performance under conditions likely to exist at a field site. 5 refs.

  10. Criticality in aqueous solutions of 3-methylpyridine and sodium bromide.

    PubMed

    Kostko, A F; Anisimov, M A; Sengers, J V

    2004-08-01

    We address a controversial issue regarding the nature of critical behavior in ternary electrolyte solutions of water, 3-methylpyridine, and sodium bromide. Earlier light-scattering studies showed an anomalous critical behavior in this system that was attributed to the formation of a microheterogeneous phase associated with ion-molecule clustering [M.A. Anisimov, J. Jacob, A. Kumar, V.A. Agayan, and J. V. Sengers, Phys. Rev. Lett. 85, 2336 (2000)

  11. Methyl Bromide Poisoning—A Bizarre Neurological Disorder

    PubMed Central

    Collins, Raymond P.

    1965-01-01

    Methyl bromide, a widely used fumigant, may cause burns of the skin, fatalities accompanied by coma and convulsions, or prolonged neurologic and psychiatric symptoms. Burns are more likely to occur where evaporation is prevented under protective clothing. Symptoms of serious illness may not develop for hours after exposure. Since action appears to be one of methylation, especially of SH groups, B.A.L. may be helpful if used promptly. PMID:14347974

  12. Structural, vibrational and theoretical studies of L-histidine bromide

    NASA Astrophysics Data System (ADS)

    Ahmed, A. Ben; Feki, H.; Abid, Y.; Boughzala, H.; Mlayah, A.

    2008-10-01

    This paper presents the results of our calculations of the geometric parameters, vibrational spectra and hyperpolarizability of a non linear optical material, L-histidine bromide. Due to the lack of sufficiently precise information on the geometric structure available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystals of L-histidine bromide have been grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2 12 12 1 of the orthorhombic system. Raman spectra have been recorded in the range [200-3500 cm -1]. All observed vibrational bands have been discussed and assigned to normal mode or to combinations and overtones on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP and BLYP) show good agreement with the experimental data. Comparison between the measured and the calculated vibrational frequencies indicate that B3LYP is superior to the scaled HF approach for molecular vibrational problems. To investigate microscopic second order non linear optical properties of L-histidine bromide, the electric dipole μ, the polarizability α and the hyperpolarizability β were computed using DFT//B3LYP/6-31G(d) method. According to our calculations, the title compound exhibits non-zero β value revealing microscopic second order NLO behaviour.

  13. The Thz Absorption of Methyl Bromide (CH_3BR)

    NASA Astrophysics Data System (ADS)

    Ramos, Marlon; Drouin, Brian J.

    2011-06-01

    The possibility of monitoring Methyl Bromide is of interest for both environmental and health concerns. It has an ozone depletion potential of 0.2% and falls under regulations of the Clean Air Act. Neurological effects from long term exposure may result from its major use as a pesticide. Recent improvements in microwave limb sounding at mm & submm wavelengths have resulted in retrievals of Methyl Chloride from atmospheric spectra. It is conceivable that Methyl Bromide would also be measurable by this technique. In an effort to extend and improve the previous work, the THz spectrum of Methyl Bromide has been measured at JPL. We used an isotopically enriched 13CH_3Br (90%) sample and recorded spectra from 750 - 1200 GHz. Our assignment covers the CH_379Br, CH_381Br, 13CH_379Br and 13CH_381Br isotopologues with J< 66 and K< 17 for the ground vibrational state. We plan to assign vibrational satellites and investigate possible perturbations near K =12 in the ground state.

  14. [Manometric effects of pinaverium bromide in irritable bowel syndrome].

    PubMed

    Soifer, L; Varela, E; Olmos, J

    1992-01-01

    The effects of pinaverium bromide on colonic motility were investigated in a controlled, controlled, cross-over study in 32 patients with irritable bowel syndrome. Constipation was clearly predominant in one group of 16 patients, and diarrhea in the other group of 16. Manometric measurements were taken of the colonic motor response generated by distention of a balloon inserted to the rectosigmoid junction. Measurements were taken before and one hour after ingestion of two tablets containing placebo or two tablets each containing 50 mg of pinaverium bromide. Following intake of placebo the motility index increased from the basal value in patients with constipation, and resistance to distention decreased in the diarrhea group. These changes were attributable to repetition of the mechanical stimulus within a relatively brief time lapse, or more probably to the ingestion of liquid which accompanied intake of tablets. Compared with placebo, pinaverium bromide induced inhibition of both effects. From the therapeutic point of view, the decrease in motility index seen in patients with irritable bowel syndrome and constipation is particularly interesting. PMID:1295286

  15. L-Tryptophan L-tryptophanium bromide: Anhydrous and monohydrate

    NASA Astrophysics Data System (ADS)

    Ghazaryan, V. V.; Giester, G.; Fleck, M.; Petrosyan, A. M.

    2015-12-01

    L-Tryptophan L-tryptophanium bromide (I) and L-tryptophan L-tryptophanium bromide monohydrate (II) are new salts with (A⋯A+) type dimeric cation. The salt (I) crystallizes in the monoclinic system (space group P21, Z = 2) and is isostructural with respective chloride (V.V. Ghazaryan et al., Spectrochim. Acta A 136(2015) 743-750), while the salt (II) was obtained previously (T. Takigawa et al., Bull. Chem. Soc. Jap. 39(1966) 2369-2378) and described as hemyhydrate without structure determination. The salt (II) crystallizes in orthorhombic system (space group P212121, Z = 4). The dimeric cations in (I) and (II) are formed by O-H⋯O hydrogen bonds with the O⋯O distances equal to 2.538(3) Å and 2.481(3) Å respectively. The infrared and Raman spectra of the crystals are studied and compared with the spectra of L-tryptophan L-tryptophanium chloride and L-tryptophanium bromide.

  16. Anomalous signal of solvent bromides used for phasing of lysozyme.

    PubMed

    Dauter, Z; Dauter, M

    1999-05-28

    The anomalous signal of bromide ions, present in the crystal structure of tetragonal hen egg-white lysozyme through the substitution of NaCl by NaBr in the crystallization medium, was used for phasing of X-ray data collected to 1.7 A resolution with a wavelength near the absorption edge of bromine. Phasing of a single wavelength data set, based purely on anomalous deltaf " contribution, led to easily interpretable electron density, equivalent to the complete multiwavelength anonalous dispersion phasing based on four-wavelength data. The classic small-structure direct methods program SHELXS run against all anomalous differences gave a successful solution of six highest peaks corresponding to six bromide ions in the structure with data limited up to a resolution of 3.5 A. Interpretable maps were obtained at a resolution up to 3.0 A using programs MLPHARE and DM. Bromide ions occupy well ordered positions at the protein surface. Phasing based on the single wavelength signal of anomalous scatterers introduced into the ordered solvent shell can be proposed as a tool for solving structures of well diffracting crystals. PMID:10339408

  17. Photodetachment of Zwitterions: Probing Intramolecular Coulomb Repulsion and Attraction in the Gas Phase Using Pyridinium Dicarboxylate Anions

    SciTech Connect

    Wang, Xue B.; Dacres, J E.; Yang, Xin; Broadus , K M.; Lis, Lev; Wang, Lai S.; Kass, Steven R.

    2003-10-23

    Zwitterions are critically important in many biological transformations and are used in numerous chemical processes. The consequences of electrostatic effects on reactivity and physical properties, however, are largely unknown. In this work, we report the results of negative ion photoelectron spectra of nine isomeric pyridinium dicarboxylate zwitterions and three nonzwitterionic methoxycarbonylpyridine carboxylate isomers (-O(2)CPyrCO(2)CH(3)). Information about the intramolecular electrostatic interactions was directly obtained from the photoelectron spectra. The adiabatic and vertical detachment energies were measured and understood in terms of intramolecular Coulombic forces. Calculations at the B3LYP and CCSD(T) level were performed and compared to the experimental electron binding energies. Structures, relative stabilities, and the electron detachment sites also were obtained from the calculations.

  18. Studies on the growth and characterization of a non linear optical crystal: 3 Hydroxy Pyridinium Tartrate Mono Hydrate (3HPTMH).

    PubMed

    Balaji, J; Prabu, S; Srinivasan, P; Srinivasan, T; Velmurugan, D

    2015-06-01

    Single crystals of 3 Hydroxy Pyridinium Tartrate Mono Hydrate (3HPTMH) was synthesised and successfully grown in mixed solvent of ethanol and water by slow evaporation technique at room temperature. 3HPTMH belongs to the orthorhombic crystal system with space group P212121. The lattice parameters of 3HPTMH are a=7.4597(2)Å, b=8.7012(3)Å, c=17.8786(5)Å, V=1160.47(6)Å(3), obtained by single crystal X ray diffraction studies. Hyperpolarizability and HOMO-LUMO analysis were performed for grown crystal using DFT calculations using Gaussian 03 software. Functional groups were identified by FT-IR studies. The lower cut-off wavelength of the 3HPTMH has been identified by UV-Vis study. The thermal behavior has been studied by thermal gravimetric analysis and differential thermal analysis. The powder second harmonic generation efficiency of 3HPTMH was compared with KDP. PMID:25754389

  19. Synthesis, structure and in vitro antibacterial activities of new hybrid disinfectants quaternary ammonium compounds: pyridinium and quinolinium stilbene benzenesulfonates.

    PubMed

    Chanawanno, Kullapa; Chantrapromma, Suchada; Anantapong, Theerasak; Kanjana-Opas, Akkharawit; Fun, Hoong-Kun

    2010-09-01

    The series of pyridinium (1-10) and quinolinium (11-20) stilbene benzenesulfonates have been synthesized and their structures were investigated by UV-vis, FT-IR and (1)H NMR spectroscopy. In addition, compound 5 was also determined by single crystal X-ray diffraction technique. The antibacterial activity of the synthesized compounds against both gram-positive and gram-negative bacteria has been determined. The quinolinium derivatives exhibited two very potent characteristic activities, namely, (i) specific activity to Methicillin-Resistant Staphylococcus aureus and (ii) with broad band spectrum activity. Compounds 11, 13 and 14 are the most active showing broad spectrum antibacterial activity against gram-positive (Methicillin-Resistant S. aureus, S. aureus, Bacillus subtilis, Vancomycin-Resistant Enterococcus faecalis and E. faecalis) and gram-negative bacterium (Shigella sonnei). The MICs of these compounds were found to be better than that of Benzalkonium chloride (BZK), the commercially used disinfectant. PMID:20619939

  20. Pyridinium-based Task-specific Ionic Liquid with a Monothioether Group for Selective Extraction of Class b Metal Ions.

    PubMed

    Chayama, Kenji; Sano, Yuki; Iwatsuki, Satoshi

    2015-01-01

    A pyridinium-based task-specific ionic liquid (TSIL) with a monothioether group, [3-TPPy][NTf2], extracted typical class b metal ions, such as Ag(I), Cu(I), Pd(II), and Pt(II), in high selectivity. It was found that the composition ratio of the extracted Ag(I) and Cu(I) species depended on the TSIL concentration, and that TSIL extracted these metal ions through mono-S-coordinated complex formation at low TSIL concentrations. [3-TPPy][NTf2] can be recycled in the extraction-recovery process, which is of a great advantage for practical use in environmentally benign separation methods. PMID:26561253

  1. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... containing residues of inorganic bromides from the use of methyl bromide are unsuitable as an ingredient in... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut...

  2. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... containing residues of inorganic bromides from the use of methyl bromide are unsuitable as an ingredient in... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut...

  3. 40 CFR 180.123a - Inorganic bromide residues in peanut hay and peanut hulls; statement of policy.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... containing residues of inorganic bromides from the use of methyl bromide are unsuitable as an ingredient in... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Inorganic bromide residues in peanut... RESIDUES IN FOOD Specific Tolerances § 180.123a Inorganic bromide residues in peanut hay and peanut...

  4. EFFECT OF BROMIDE ION IN WATER TREATMENT. 2. A LITERATURE REVIEW OF OZONE AND BROMIDE ION INTERACTIONS AND THE FORMATION OF ORGANIC BROMINE COMPOUNDS

    EPA Science Inventory

    Where bromide ion is found in water used as a source of drinking water, and chlorination is used for disinfection, bromide ion is oxidized to bromine and can result in the formation of organic bromine compounds. There are presently no treatment techniques available for economic r...

  5. Spatial Variation Scales of Rainfall Characteristics and Bromide Leaching

    NASA Astrophysics Data System (ADS)

    Wendroth, O. O.; Vasquez, V.; Matocha, C.

    2010-12-01

    Amount and intensity of rainfall are known as important characteristics that affect the leaching of surface-applied agri-chemicals. Besides these, the effect of the time interval between a fertilizer, pesticide or tracer application and subsequent rainfall on solute leaching is not well understood. Moreover, little is known about the spatial representativity of the solute concentration based on a relatively small soil sample in field-scale transport studies. To know the spatial representativity of a solute concentration sample at a time is crucial for analyzing solute leaching behavior over time as well as over space. The objectives of this study were to identify the impact of rainfall intensity and amount as well as the application time delay on solute transport in a well-drained Maury silt loam soil. Moreover, an experimental design and protocol had to be developed that exhibited spatial variability structure and representativity of bromide concentration. For this purpose, the variation scale of each of the factors investigated was chosen differently to apply frequency domain statistics. The study was conducted in a Maury silt loam soil at the University of Kentucky, College of Agriculture Experimental Farm Spindletop. Along a 64-m transect, 32 plots each 2-m long and 4-m wide were established. The three different treatments were spatially laid out in sinusoidal patterns at three respective wavelengths. Two different rainfall amounts were applied in blocks of eight consecutive plots, hence a wavelength of 32 m. These two different rainfall amounts were applied at four rates, spatially distributed in two waves each of 16 m length. Individual plots received the irrigation at specific times after the tracer had been applied. Four application delay times were chosen, hence the wavelength for this treatment was 8 m. Bromide concentration was measured for soil samples that were taken with a percussion auger at every 50 cm distance along the 64-m-transect. Auger cores

  6. Comparison of Heat and Bromide as Ground Water Tracers Near Streams

    USGS Publications Warehouse

    Constantz, J.; Cox, M.H.; Su, G.W.

    2003-01-01

    Heat and bromide were compared as tracers for examining stream/ground water exchanges along the middle reaches of the Santa Clara River, California, during a 10-hour surface water sodium bromide injection test. Three cross sections that comprise six shallow (<1 m) piezometers were installed at the upper, middle, and lower sections of a 17 km long study reach, to monitor temperatures and bromide concentrations in the shallow ground water beneath the stream. A heat and ground water transport simulation model and a closely related solute and ground water transport simulation model were matched up for comparison of simulated and observed temperatures and bromide concentrations in the streambed. Vertical, one-dimensional simulations of sediment temperature were fitted to observed temperature results, to yield apparent streambed hydraulic conductivities in each cross section. The temperature-based hydraulic conductivities were assigned to a solute and ground water transport model to predict sediment bromide concentrations, during the sodium bromide injection test. Vertical, one-dimensional simulations of bromide concentrations in the sediments yielded a good match to the observed bromide concentrations, without adjustment of any model parameters except solute dispersivities. This indicates that, for the spatial and temporal scales examined on the Santa Clara River, the use of heat and bromide as tracers provide comparable information with respect to apparent hydraulic conductivities and fluxes for sediments near streams. In other settings, caution should be used due to differences in the nature of conservative (bromide) versus nonconservative (heat) tracers, particularly when preferential flowpaths are present.

  7. Crystal structure of 1-[(1-methyl-5-nitro-1H-imidazol-2-yl)meth­yl]pyridinium iodide

    PubMed Central

    Belguedj, Roumaissa; Bouraiou, Abdelmalek; Merazig, Hocine; Belfaitah, Ali; Bouacida, Sofiane

    2015-01-01

    In the title salt, C10H11N4O2 +·I−, the asymmetric unit consists of a pyridinium cation bearning a (1-methyl-5-nitro-1H-imidazol-2-yl)methyl group at the N position and an iodide anion. The imidazole ring is quasiplanar, with a maxiumum deviation of 0.0032 (16) Å, and forms a dihedral angle of 67.39 (6)° with the plane of the pyridinium ring. The crystal packing can be described as alternating zigzag layers of cations parallel to the (001) plane, which are sandwiched by the iodide ions. The structure features two types of hydrogen bonds (C—H⋯O and C—H⋯I), viz. cation–anion and cation–cation, which lead to the form ation of a three-dimensional network. PMID:25878869

  8. Chemically induced Parkinson's disease: intermediates in the oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to the 1-methyl-4-phenyl-pyridinium ion

    SciTech Connect

    Chacon, J.N.; Chedekel, M.R.; Land, E.J.; Truscott, T.G.

    1987-04-29

    Various unstable intermediate oxidation states have been postulated in the metabolic activation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to the 1-methyl-4-phenyl pyridinium ion. We now report the first direct observation of these free radical intermediates by pulse radiolysis and flash photolysis. Studies are described of various reactions of such species, in particular with dopamine whose autoxidation to dopamine quinone is reported to be potentiated by 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine.

  9. Automated determination of bromide in waters by ion chromatography with an amperometric detector

    USGS Publications Warehouse

    Pyen, G.S.; Erdmann, D.E.

    1983-01-01

    An automated ion chromatograph, including a program controller, an automatic sampler, an integrator, and an amperometric detector, was used to develop a procedure for the determination of bromide in rain water and many ground waters. Approximately 10 min is required to obtain a chromatogram. The detection limit for bromide is 0.01 mg l-1 and the relative standard deivation is <5% for bromide concentrations between 0.05 and 0.5 mg l-1. Chloride interferes if the chloride-to-bromide ratio is greater than 1 000:1 for a range of 0.01-0.1 mg l-1 bromide; similarly, chloride interferes in the 0.1-1.0 mg l-1 range if the ratio is greater than 5 000:1. In the latter case, a maximum of 2 000 mg l-1 of chloride can be tolerated. Recoveries of known concentrations of bromide added to several samples, ranged from 97 to 110%. ?? 1983.

  10. Interaction between gaseous ozone and crystalline potassium bromide

    NASA Astrophysics Data System (ADS)

    Levanov, A. V.; Maksimov, I. B.; Isaikina, O. Ya.; Antipenko, E. E.; Lunin, V. V.

    2016-07-01

    The formation of nonvolatile products of the oxidation of a bromide ion during the interaction between gaseous ozone and powdered crystalline KBr is studied. It is found that potassium bromate KBrO3 is the main product of the reaction. The influence of major experimental factors (the duration of ozonation, the concentration of ozone, the humidity of the initial gas, and the temperature) on the rate of formation of bromate is studied. The effective constants of the formation of bromate during the interaction between O3 and Br- in a heterogeneous gas-solid body system and in a homogeneous aqueous solution are compared.

  11. Photodissociation of methyl chloride and methyl bromide in the atmosphere

    NASA Technical Reports Server (NTRS)

    Robbins, D. E.

    1976-01-01

    Methyl chloride (CH3Cl) and methyl bromide (CH3Br) have been suggested to be significant sources of the stratospheric halogens. The breakup of these compounds in the stratosphere by photodissociation or reaction with OH releases halogen atoms which catalytically destroy ozone. Experimental results are presented for ultraviolet photoabsorption cross sections of CH3Cl and CH3Br. Calculations are presented of loss rates for the methyl halides due to photodissociation and reaction with OH and of mixing ratios of these species in the stratosphere.

  12. 2-[(E)-2-(4-Chloro­phen­yl)ethen­yl]-1-methyl­pyridinium 4-chloro­benzene­sulfonate

    PubMed Central

    Fun, Hoong-Kun; Chanawanno, Kullapa; Chantrapromma, Suchada

    2009-01-01

    In the title salt, C14H13ClN+·C6H4ClO3S−, the cation exists in an E configuration with respect to the ethynyl bond and is approximately planar, with a dihedral angle of 3.4 (2)° between the pyridinium and benzene rings. The anion is approximately perpendicular to the cation plane, the benzene ring of the anion making dihedral angles of 89.4 (2) and 89.9 (2)°, respectively, with the pyridinium and benzene rings of the cation. In the crystal structure, the cations are linked into a chain along the c axis by C—H⋯Cl inter­actions. The anions are linked to the adjacent cation chains by C—H⋯O and C—H⋯Cl inter­actions, forming a two-dimensional network parallel to the bc plane. The crystal structure is further stabilized by C—H⋯π inter­actions. A π–π inter­action is also observed between the pyridinium ring and the benzene ring of the cation with a centroid–centroid distance of 3.668 (3) Å. PMID:21582839

  13. Synthesis and antibacterial activity of pyridinium-tailored 2,5-substituted-1,3,4-oxadiazole thioether/sulfoxide/sulfone derivatives.

    PubMed

    Wang, Pei-Yi; Zhou, Lei; Zhou, Jian; Wu, Zhi-Bing; Xue, Wei; Song, Bao-An; Yang, Song

    2016-02-15

    By introducing the pyridinium group into 2,5-substituted-1,3,4-oxadiazole, a series of pyridinium-tailored 2,5-substituted-1,3,4-oxadiazole thioether/sulfoxide/sulfone derivatives were obtained, and their antibacterial activities were evaluated via turbidimeter test in vitro. The bioassays reveal that most of the target compounds exhibit better inhibition activities against pathogen Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas axonopodis pv. citri than positive controls bismerthiazol (CK1) or thiodiazole copper (CK2). Among them, I-8, I-10, I-12, II-10, II-12, III-10, and III-12 exert excellent inhibition activities against the three pathogenic bacteria with the half-maximal effective concentration (EC50) values ranging from 0.54 to 12.14 μg/mL. Our results demonstrate that pyridinium-tailored 1,3,4-oxadiazole thioether/sulfoxide/sulfone derivatives can serve as potential alternative bactericides for the management of plant bacterial diseases. PMID:26810264

  14. Effects of pinaverium bromide and verapamil on the motility of the rat isolated colon.

    PubMed

    Baumgartner, A; Drack, E; Halter, F; Scheurer, U

    1985-09-01

    Pinaverium bromide was 30 times less potent than verapamil in inhibiting intraluminal pressure responses of in vitro rat colonic segments to barium chloride, acetylcholine, FK 33-824 or field stimulation. The inhibitory effects of both verapamil and pinaverium bromide on the pressure responses to field stimulation were antagonized similarly by exogenous calcium administration. These results support the concept that pinaverium bromide acts on calcium channels in the smooth muscle cell membrane. PMID:4052731

  15. Effects of pinaverium bromide and verapamil on the motility of the rat isolated colon.

    PubMed Central

    Baumgartner, A.; Drack, E.; Halter, F.; Scheurer, U.

    1985-01-01

    Pinaverium bromide was 30 times less potent than verapamil in inhibiting intraluminal pressure responses of in vitro rat colonic segments to barium chloride, acetylcholine, FK 33-824 or field stimulation. The inhibitory effects of both verapamil and pinaverium bromide on the pressure responses to field stimulation were antagonized similarly by exogenous calcium administration. These results support the concept that pinaverium bromide acts on calcium channels in the smooth muscle cell membrane. PMID:4052731

  16. Transient neuromyopathy after bromide intoxication in a dog with idiopathic epilepsy

    PubMed Central

    2012-01-01

    A seven-year old Australian Shepherd, suffering from idiopathic epilepsy under treatment with phenobarbitone and potassium bromide, was presented with generalised lower motor neuron signs. Electrophysiology and muscle-nerve biopsies revealed a neuromyopathy. The serum bromide concentration was increased more than two-fold above the upper reference value. Clinical signs disappeared after applying diuretics and reducing the potassium bromide dose rate. This is the first case report describing electrophysiological and histopathological findings associated with bromide induced lower motor neuron dysfunction in a dog. PMID:23216950

  17. IUPAC-NIST Solubility Data Series. 94. Rare Earth Metal Iodides and Bromides in Water and Aqueous Systems. Part 2. Bromides

    NASA Astrophysics Data System (ADS)

    Mioduski, Tomasz; Gumiński, Cezary; Zeng, Dewen; Voigt, Heidelore

    2013-03-01

    This work presents solubility data for rare earth metal bromides in water and in aqueous ternary systems. Compilations of all available experimental data are introduced for each rare earth metal bromide with a corresponding critical evaluation. Every such evaluation contains a collection of all solubility results in water, a selection of suggested solubility data and a brief discussion of the multicomponent systems. Because the ternary systems were almost never studied more than once, no critical evaluations of such data were possible. Only simple bromides (no complexes) are treated as the input substances in this work. The literature has been covered through the end of 2011.

  18. Bromoform formation in ozonated groundwater containing bromide and humic substances

    SciTech Connect

    Cooper, W.J.; Amy, G.L.; Moore, C.A.; Zika, R.G.

    1986-01-01

    The effect of bromide ion, organic carbon concentration (natural aquatic humic substances), pH, and solar irradiation on the formation of bromoform in ozonated groundwater has been studied. The studies were conducted on four unique samples of groundwater taken from different regions of the Biscayne Aquifer in southern Florida. All other conditions being equal, increases in bromide ion concentrations resulted in increases in CHBr/sub 3/ formation. In three of the four samples, CHBr/sub 3/ formation decreased as the pH level increased from 5 to 9. The fourth sample exhibited an opposite trend whereby the CHBr/sub 3/ concentration increased with increasing pH. Bromoform concentration increased with increased O/sub 3/ concentration over an ozone dosage range of 3.4 to 6.7 mg/L. Ozonated samples placed in sunlight immediately after ozone addition showed a decrease in the formation of CHBr/sub 3/ presumably due to the photodecomposition of HOBr/OBr.

  19. A two-step ICT process for solvatochromic betaine pyridinium revealed by ultrafast spectroscopy, multivariate curve resolution, and TDDFT calculations.

    PubMed

    Aloïse, Stéphane; Pawlowska, Zuzanna; Ruckebusch, Cyril; Sliwa, Michel; Dubois, Julien; Poizat, Olivier; Buntinx, Guy; Perrier, Aurélie; Maurel, François; Jacques, Patrice; Malval, Jean-Pierre; Poisson, Lionel; Piani, Giovanni; Abe, Jiro

    2012-02-14

    This work deals with the photophysics of a pyridinium betaine, 2-pyridin-1-yl-1H-benzimidazole (SBPa), based on a combination of steady-state, femtosecond photoionization (gas phase) and femtosecond transient absorption (solution) spectroscopic measurements, supported by (LR)-PCM-(TD)DFT calculations. Preliminary and new electrochemical results have revealed a strongly negative solvatochromic charge transfer (CT) absorption due to a S(0) → S(2) vertical transition and a weakly-solvatochromic emission due to S(1) → S(0) transition. Advanced TDDFT optimizations of the Franck-Condon states S(2)(FC) and S(1)(FC) led to two additional CT levels with planar geometry, S(2)(CT) and S(1)(CT), respectively, allowing prediction of a two-step photoinduced ICT process, i.e., S(0) → S(2)(FC) and S(2)(CT) → S(1)(CT), separated by a S(2)(FC) → S(2)(CT) back charge transfer relaxation. While the pyridinium ring is the acceptor group in both steps, two different donor groups, the benzene ring and the imidazole bridge, are involved in the excitation and internal conversion processes, respectively. Femtosecond transient absorption experiments supported by MCR-ALS decomposition confirmed indeed the contribution of two distinct CT states in the photophysics of SBPa: following excitation to the S(2)(CT) state, ultrafast production of the emissive S(1) state (the only channel observable in the gas phase) was observed to occur in competition with a further ICT process toward the S(1)(CT) state, with a time constant ranging from 300 fs to 20 ps depending on the solvent. While in aprotic media this ICT process was found to be purely solvent controlled (double polarity and viscosity dependency), in protic solvents, the influence of the hydrogen bond network has to be taken into account. Comparison with data obtained for a pre-twisted SBPa analogue led us to exclude the presence of any large-amplitude geometrical change during ICT. Analyzing the solvent dependency using the power law

  20. The distribution of bromide in water in the Floridan aquifer system, Duval County, northeastern Florida

    USGS Publications Warehouse

    German, E.R.; Taylor, G.F.

    1995-01-01

    Although Duval County, Florida, has ample ground-water resources for public supply, the potential exists for a problem with excessive disinfectant by-products. These disinfectant by-products result from the treatment of raw water containing low concentrations of bromide and naturally occurring organic compounds. Because of this potential problem, the relation of bromide concentrations to aquifer tapped, well location and depth, and chemical characteristics of water in the Floridan aquifer system underlying Duval County were studied to determine if these relations could be applied to delineate water with low-bromide concentrations for future supplies. In 1992, water samples from 106 wells that tap the Floridan aquifer system were analyzed for bromide and major dissolved constituents. A comparison of bromide concentrations from the 1992 sampling with data from earlier studies (1979-80) indicates that higher bromide concentrations were detected during the earlier studies. The difference between the old and new data is probably because of a change in analytical methodology in the analysis of samples. Bromide concentrations exceeded the detection limit (0.10 milligrams per liter) in water from 28 of the 106 wells (26 percent) sampled in 1992. The maximum concentration was 0.56 milligrams per liter. There were no relations between bromide and major dissolved constituents, well depth, or aquifer tapped that would be useful for determining bromide concentrations. Areal patterns of bromide occurrence are not clearly defined, but areas with relatively high bromide concentrations tend to be located in a triangular area near the community of Sunbeam, Florida, and along the St. Johns River throughout Duval County.

  1. Validation of an automated fluorescein method for determining bromide in water

    USGS Publications Warehouse

    Fishman, M. J.; Schroder, L.J.; Friedman, L.C.

    1985-01-01

    Surface, atmospheric precipitation and deionized water samples were spiked with ??g l-1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l-1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l-1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.Surface, atmospheric precipitation and deionized water samples were spiked with mu g l** minus **1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0. 015 to 0. 5 mg l** minus **1 of bromide. The correlation coefficient for the same sets of paired data is 0. 9987. Recovery data, except for the surface water samples to which 0. 005 mg l** minus **1 of bromide was added, range from 89 to 112%. Refs.

  2. Confinement of pyridinium hemicyanine dye within an anionic metal-organic framework for two-photon-pumped lasing

    PubMed Central

    Yu, Jiancan; Cui, Yuanjing; Xu, Hui; Yang, Yu; Wang, Zhiyu; Chen, Banglin; Qian, Guodong

    2013-01-01

    Two-photon-pumped dye lasers are very important because of their applications in wavelength up-conversion, optical data storage, biological imaging and photodynamic therapy. Such lasers are very difficult to realize in the solid state because of the aggregation-caused quenching. Here we demonstrate a new two-photon-pumped micro-laser by encapsulating the cationic pyridinium hemicyanine dye into an anionic metal-organic framework (MOF). The resultant MOF⊃dye composite exhibits significant two-photon fluorescence because of the large absorption cross-section and the encapsulation-enhanced luminescent efficiency of the dye. Furthermore, the well-faceted MOF crystal serves as a natural Fabry–Perot resonance cavity, leading to lasing around 640 nm when pumped with a 1064-nm pulse laser. This strategy not only combines the crystalline benefit of MOFs and luminescent behaviour of organic dyes but also creates a new synergistic two-photon-pumped lasing functionality, opening a new avenue for the future creation of solid-state photonic materials and devices. PMID:24173352

  3. New series of monoquaternary pyridinium oximes: synthesis and reactivation potency for paraoxon-inhibited electric eel and recombinant human acetylcholinesterase

    PubMed Central

    Bharate, Sandip B.; Guo, Lilu; Reeves, Tony E.; Cerasoli, Douglas M.; Thompson, Charles M.

    2009-01-01

    The preparation of a series of monoquaternary pyridinium oximes bearing either a heterocyclic side chain or a functionalized aliphatic side chain and the corresponding in vitro evaluation for reactivation of paraoxon-inhibited electric eel acetylcholinesterase (EeAChE) and recombinant human acetylcholinesterase (rHuAChE) are reported. Several newly synthesized compounds efficiently reactivated inhibited EeAChE, but were poor reactivators of inhibited rHuAChE. Compounds bearing a thiophene ring in the side chain (20, 23, 26 and 29) showed better reactivation (24–37% for EeAChE and 5–9% for rHuAChE) compared to compounds with furan and isoxazole heterocycles (0–8% for EeAChE and 2–3% for rHuAChE) at 10−5 M. The N-pyridyl-CH2COOH analog 8 reactivated EeAChE (36%) and rHuAChE (15%) at 10−4 M with a kr value better than 2-pyridine aldoxime methiodide (2-PAM) for rHuAChE. PMID:19640713

  4. Nickel-pincer cofactor biosynthesis involves LarB-catalyzed pyridinium carboxylation and LarE-dependent sacrificial sulfur insertion.

    PubMed

    Desguin, Benoît; Soumillion, Patrice; Hols, Pascal; Hausinger, Robert P

    2016-05-17

    The lactate racemase enzyme (LarA) of Lactobacillus plantarum harbors a (SCS)Ni(II) pincer complex derived from nicotinic acid. Synthesis of the enzyme-bound cofactor requires LarB, LarC, and LarE, which are widely distributed in microorganisms. The functions of the accessory proteins are unknown, but the LarB C terminus resembles aminoimidazole ribonucleotide carboxylase/mutase, LarC binds Ni and could act in Ni delivery or storage, and LarE is a putative ATP-using enzyme of the pyrophosphatase-loop superfamily. Here, we show that LarB carboxylates the pyridinium ring of nicotinic acid adenine dinucleotide (NaAD) and cleaves the phosphoanhydride bond to release AMP. The resulting biscarboxylic acid intermediate is transformed into a bisthiocarboxylic acid species by two single-turnover reactions in which sacrificial desulfurization of LarE converts its conserved Cys176 into dehydroalanine. Our results identify a previously unidentified metabolic pathway from NaAD using unprecedented carboxylase and sulfur transferase reactions to form the organic component of the (SCS)Ni(II) pincer cofactor of LarA. In species where larA is absent, this pathway could be used to generate a pincer complex in other enzymes. PMID:27114550

  5. Crystal structure of bis-(1-hexyl-N,N-di-methyl-pyridinium) bis-(maleo-nitrile-dithiol-ato)nickelate(II).

    PubMed

    Yu, Shan-Shan; Zhang, Hui

    2016-08-01

    The asymmetric unit of the title compound, (C13H23N2)2[Ni(C4N2S2)2], consists of a 1-hexyl-N,N-di-methyl-pyridinium cation and one half of a [Ni(mnt)2](2-) dianion (mnt(2-) = maleo-nitrile-dithiol-ate) in which the Ni(2+) cation lies on a crystallographic inversion centre. The square-planar coordination about Ni(2+) comprises four S atoms from two bidentate chelate mnt(2-) ligands [Ni-S = 2.1791 (9) and 2.1810 (8) Å, and S-Ni-S bite angle = 91.93 (3)°]. The hydro-carbon chains of cations show trans-planar conformations and lie approximately parallel to the long mol-ecular axis of the [Ni(mnt)2](2-) anions, giving stacks along the c axis. The anions and cations form layers lying parallel to the bc plane. Only weak C-H⋯Ni and C-H⋯π associations are present in the crystal packing. PMID:27536413

  6. Removal of bromide by aluminium chloride coagulant in the presence of humic acid.

    PubMed

    Ge, Fei; Shu, Haimin; Dai, Youzhi

    2007-08-17

    Bromide can form disinfection by-products (DBPs) in drinking water disinfection process, which have adverse effects on human health. Using aluminium chloride as a model coagulant, removal of bromide by coagulation was investigated in the absence or presence of humic acid (HA) in synthetic water and then was conducted in raw water. Results demonstrated that in synthetic water, 93.3-99.2% removal efficiency of bromide was achieved in the absence of HA with 3-15 mg/L coagulant, while 78.4-98.4% removal efficiency of bromide was obtained in the presence of HA with the same coagulant dosage and 86.8-98.8% HA was removed simultaneously. Bromide in raw water was removed 87.0% with 15 mg/L coagulant. HA apparently reduced the removal of bromide with low coagulant dosage or at high pH, while minor influence on removal of bromide was observed with high coagulant dosage or at low pH. Thus, bromide could be reduced effectively by enhanced coagulation in drinking water treatment. PMID:17289257

  7. Solid phase microextraction for active or passive sampling of methyl bromide during fumigations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The high diffusivity and volatility of methyl bromide make it an ideal compound for Solid Phase Micro Extraction (SPME)-based sampling of air prior to gas-chromatographic quantifications. SPME fibers can be used as active methyl bromide samplers, with high capacities and an equilibrium time of 1-2 m...

  8. Enthalpies of complex formation of boron and aluminum bromides with organic bases of high donor power

    SciTech Connect

    Grigor-ev, A.A.; Kondrat'ev, Y.V.; Suvorov, A.V.

    1986-11-20

    By the calorimetric method enthalpies of complex formation were determined for boron and aluminum bromides with piperidine and hexamethylphosphoric triamide in benzene solutions and for boron bromide with pyridine in dichloroethane, and also enthalpies of solution were determined for BBr/sub 3/ and the adducts AlBr/sub 3/ x PPy and BBr/sub 2/ x Py in benzene and pyridine.

  9. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide is widely used as a fumigant for post-harvest and quarantine uses at port facilities due to the low treatment times required, but it is vented to the atmosphere after its use. Due to the potential contributions of methyl bromide to stratospheric ozone depletion, technologies for the c...

  10. Palladium-Catalyzed Selective α-Alkenylation of Pyridylmethyl Ethers with Vinyl Bromides.

    PubMed

    Yang, Xiaodong; Kim, Byeong-Seon; Li, Minyan; Walsh, Patrick J

    2016-05-20

    An efficient palladium-catalyzed α-alkenylation of pyridylmethyl ethers with vinyl bromides is presented. A Pd/NIXANTPHOS-based catalyst system enables a mild and chemoselective coupling between a variety of pyridylmethyl ethers and vinyl bromides in good to excellent yields. Under the mild conditions, β,γ-unsaturated products are obtained without isomerization or Heck byproducts observed. PMID:27160421

  11. 77 FR 48153 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-13

    ...On May 17, 2012, the EPA published a notice in the Federal Register requesting applications for the Critical Use Exemption from the phaseout of methyl bromide for 2015. On August 3, 2012, EPA received a letter from methyl bromide stakeholders requesting an extension to the August 15, 2012 deadline for submitting Critical Use Exemption applications. The letter requested a deadline of August 29,......

  12. 76 FR 34700 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-14

    ... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications... exemption from the phaseout of methyl bromide for 2014. Critical use exemptions last only one year. All... interested parties to provide EPA with new data on the technical and economic feasibility of methyl...

  13. 75 FR 41177 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-15

    ... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications... exemption from the phaseout of methyl bromide for 2013. Critical use exemptions last only one year. All... interested parties to provide EPA with new data on the technical and economic feasibility of methyl...

  14. In vivo and in vitro bromide equilibration time course in adults and sample handling effect

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extracellular water is a major component of body weight and an indicator of nutritional status. Bromide dilution has been used to estimate this compartment. Recent evidence, however, indicates that the bromide equilibration time is longer than the 4 hr assumed in many studies. The aim of this stud...

  15. Methyl bromide fumigation of packed table grapes: Effect of shipping box on gas concentrations and phytotoxicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current methyl bromide schedules for table grapes to control mealybugs are approved for fruit packed in Toyon Kraft Veneer (TKV) boxes. The question arose concerning equivalence of exposure to methyl bromide if an Extruded Polystyrene (EPS) box was used in lieu of the TKV box for table grapes being ...

  16. Performance of soil solarization and methyl bromide in sites infested with root-knot nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil fumigation with methyl bromide has been the principal means of managing soil-borne pest problems on ornamental crops in the United States for many years. Interest in effective alternatives increased during the phase-out of methyl bromide, and will become more acute as existing stocks are deple...

  17. Classifying the Basic Parameters of Ultraviolet Copper Bromide Laser

    NASA Astrophysics Data System (ADS)

    Gocheva-Ilieva, S. G.; Iliev, I. P.; Temelkov, K. A.; Vuchkov, N. K.; Sabotinov, N. V.

    2009-10-01

    The performance of deep ultraviolet copper bromide lasers is of great importance because of their applications in medicine, microbiology, high-precision processing of new materials, high-resolution laser lithography in microelectronics, high-density optical recording of information, laser-induced fluorescence in plasma and wide-gap semiconductors and more. In this paper we present a statistical study on the classification of 12 basic lasing parameters, by using different agglomerative methods of cluster analysis. The results are based on a big amount of experimental data for UV Cu+ Ne-CuBr laser with wavelengths 248.6 nm, 252.9 nm, 260.0 nm and 270.3 nm, obtained in Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences. The relevant influence of parameters on laser generation is also evaluated. The results are applicable in computer modeling and planning the experiments and further laser development with improved output characteristics.

  18. Unveiling Residual Molecular Binding in Triply Charged Hydrogen Bromide

    SciTech Connect

    Penent, F.; Lablanquie, P.; Palaudoux, J.; Gamblin, G.; Carniato, S.; Andric, L.; Hikosaka, Y.; Ito, K.

    2011-03-11

    We present an experimental and theoretical study of triply charged hydrogen bromide ions formed by photoionization of the inner 3d shell of Br. The experimental results, obtained by detecting the 3d photoelectron in coincidence with the two subsequent Auger electrons, are analyzed using calculated potential energy curves of HBr{sup 3+}. The competition between the short-range chemical binding potential and the Coulomb repulsion in the dissociative process is shown. Two different mechanisms are observed for double Auger decay: one, a direct process with simultaneous ejection of two Auger electrons to final HBr{sup 3+} ionic states and the other, a cascade process involving double Auger decay characterized by the autoionization of Br*{sup +} ion subsequent to the HBr{sup 2+} fragmentation.

  19. Thermal parameters of carbon nanotubes and potassium bromide composites

    NASA Astrophysics Data System (ADS)

    Depriester, Michael; Hus, Philippe; Sahraoui, Abdelhak Hadj; Roussel, Frédérick

    2011-04-01

    Photothermal radiometry is employed to investigate the thermal parameters (diffusivity, effusivity, conductivity, and heat capacity) of carbon nanotubes [single-walled (SWNT) or multiple-walled (MWNT)] and potassium bromide (KBr) pressed pellets as a function of SWNT or MWNT mass fraction. A significant enhancement of the thermal conductivity for carbon nanotubes (CNTs) contents up to 2 wt. % was observed. Above 3 wt. % CNT, a morphological transition from a compacted to an unconsolidated granular media occurs leading to a sharp decrease of the thermal conductivity (k) caused by the presence of air interfaces. A geometrical model based on interpenetrating continua is applied to describe the unusual evolution of the thermal conductivity. The behavior of k is also discussed in regard to the latest theoretical reports.

  20. Timing resolution measurements of a 3 in. lanthanum bromide detector

    NASA Astrophysics Data System (ADS)

    Galli, L.; De Gerone, M.; Dussoni, S.; Nicolò, D.; Papa, A.; Tenchini, F.; Signorelli, G.

    2013-08-01

    Cerium-doped lanthanum bromide (LaBr3:Ce) is a scintillator that presents very good energy and timing resolutions and it is a perfect candidate for photon detector in future experiments to search for lepton flavor violation as in μ → eγ or μ → e conversion. While energy resolution was thoroughly investigated, timing resolution at several MeV presents some experimental challenge. We measured the timing resolution of a 3 in.×3 in. cylindrical LaBr3(Ce) crystal versus few reference detectors by means of a nuclear reaction from a Cockcroft-Walton accelerator that produces coincident γ-rays in the 4.4-11.6 MeV range. Preliminary results allow us to extrapolate the properties of a segmented γ-ray detector in the 50-100 MeV range.

  1. Tiotropium Bromide in Chronic Obstructive Pulmonary Disease and Bronchial Asthma

    PubMed Central

    Alvarado-Gonzalez, Alcibey; Arce, Isabel

    2015-01-01

    Inhaled bronchodilators are the mainstay of pharmacological treatment for stable chronic obstructive pulmonary disease (COPD), including β2-agonists and muscarinic antagonists. Tiotropium bromide, a long-acting antimuscarinic bronchodilator (LAMA), is a treatment choice for moderate-to-severe COPD; its efficacy and safety have been demonstrated in recent trials. Studies also point to a beneficial role of tiotropium in the treatment of difficult-to-control asthma and a potential function in the asthma-COPD overlap syndrome (ACOS). Combination of different bronchodilator molecules and addition of inhaled corticosteroids are viable therapeutic alternatives. A condensation of the latest trials and the rationale behind these therapies will be presented in this article. PMID:26491494

  2. Simultaneous electrochemical determination of three sunscreens using cetyltrimethylammonium bromide.

    PubMed

    Cardoso, Juliano Carvalho; Armondes, Bruna Milca Lenzi; Ferreira, João Bosco Galindo Júnior e Valdir Souza

    2008-05-01

    This paper proposes a methodology based on electrochemical reduction for the simultaneous determination of three sunscreen agents, namely 4-methylbenzylidene camphor (MBC), benzophenone-3 (BENZO) and 2-ethylhexyl-4-methoxycinnamate (EHMC) by differential-pulse polarography (DPP). The highest peak currents and optimal separation of reduction peaks were obtained by using a supporting electrolyte consisted of Britton-Robinson buffer-methanol (8:2) solution at pH 4.0 and cationic surfactant 3.0 x 10(-4)mol L(-1) cetyltrimethylammonium bromide (CTAB). The methodology was validated using four commercial sunscreen preparation as a sample and the results showed high recovery rates. The efficiency of the proposed methodology was demonstrated by comparing the results obtained by DPP with those obtained by the high-performance liquid chromatography (HPLC) method. PMID:18093812

  3. Absorption of Water Vapor into Aqueous Solutions of Lithium Bromide

    NASA Astrophysics Data System (ADS)

    Takahara, Tsutomu; Hayashida, Atsushi; Yabase, Hajime; Hihara, Eiji; Saito, Takamoto

    Heat and mass transfer processes are experimentally investigated for the case of water absorption into aqueous solutions of lithium bromide flowing over a flat plate. Variables considered are inlet solution flow rate,concentration of an additive,and inclination angle of the plate. The use of 2-ethyl-1-hexanol as an additive results in about a four to five fold improvement in absorption rate. The occurrence of surface distrbances dose not has a direct connection with the solubility limit of the additive. The cause of the surface disturbances in the presence of additives is investigated through experiments for pool absorption By regulating the flow of water vapor,the form of the Marangoni convection can be controlled. A qualitative discussion of addictives in the role of inducing surface disturbances is presented.

  4. Location of Bromide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions have been shown to play a dominant role in the crystallization of chicken egg white lysozyme from salt solutions. Previous studies employing X-ray crystallography had found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystal grown in bromide and chloride solutions. Five possible anion binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four of these sites corresponded to four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion binding sites in lysozyme remain unchanged, even when different anions and different crystal forms of lysozyme are employed.

  5. Detecting Arbitrary DNA Mutations Using Graphene Oxide and Ethidium Bromide.

    PubMed

    Huang, Jiahao; Wang, Zhenyu; Kim, Jang-Kyo; Su, Xuefen; Li, Zhigang

    2015-12-15

    We propose a simple and fast method for detecting arbitrary DNA mutations. Single-stranded DNA probes labeled with fluorescein amidite (FAM-ssDNA), ethidium bromide (EB), and graphene oxide (GO) are employed in the sensing system. The detection is achieved in two steps. In the first step, the sensing system contains FAM-ssDNA probes and EB molecules. It exhibits different fluorescence emissions in the presence of perfectly matched, mismatched, and random DNA sequences. With the addition of GO in the second step, the fluorescence signal for perfectly matched and random DNA does not vary greatly, which, however, experiences a significant change for mismatched DNA targets. The signal ratio before and after the addition of GO can clearly distinguish mutations from normal and random DNA sequences. The detection method works well regardless of the mutation positions and only requires "mix-and-detect" steps, which are completed within 15 min. PMID:26559174

  6. N-(2-Bromo­benz­yl)cinchoninium bromide

    PubMed Central

    Skórska-Stania, Agnieszka; Jezierska-Zięba, Magdalena; Kąkol, Barbara; Fedoryński, Michał; Oleksyn, Barbara J.

    2012-01-01

    The title compound {systematic name: 1-(2-bromo­benz­yl)-5-ethenyl-2-[hy­droxy(quinolin-4-yl)meth­yl]-1-aza­bicyclo­[2.2.2]octan-1-ium bromide}, C26H28BrN2O+·Br−, is a chiral quater­nary ammonium salt of one of the Cinchona alkaloids. The planes of the quinoline and of the bromo­benzyl substituent are inclined to one another by 9.11 (9)°. A weak intra­molecular C—H⋯O hydrogen bond occurs. The crystal structure features strong O—H⋯Br hydrogen bonds and weak C—H⋯Br inter­actions. PMID:22969676

  7. Error Evaluation of Methyl Bromide Aerodynamic Flux Measurements

    USGS Publications Warehouse

    Majewski, M.S.

    1997-01-01

    Methyl bromide volatilization fluxes were calculated for a tarped and a nontarped field using 2 and 4 hour sampling periods. These field measurements were averaged in 8, 12, and 24 hour increments to simulate longer sampling periods. The daily flux profiles were progressively smoothed and the cumulative volatility losses increased by 20 to 30% with each longer sampling period. Error associated with the original flux measurements was determined from linear regressions of measured wind speed and air concentration as a function of height, and averaged approximately 50%. The high errors resulted from long application times, which resulted in a nonuniform source strength; and variable tarp permeability, which is influenced by temperature, moisture, and thickness. The increase in cumulative volatilization losses that resulted from longer sampling periods were within the experimental error of the flux determination method.

  8. Rejection of Bromide and Bromate Ions by a Ceramic Membrane

    PubMed Central

    Moslemi, Mohammadreza; Davies, Simon H.; Masten, Susan J.

    2012-01-01

    Abstract Effects of pH and the addition of calcium chloride (CaCl2) on bromate (BrO3−) and bromide (Br−) rejection by a ceramic membrane were investigated. Rejection of both ions increased with pH. At pH 8, the rejection of BrO3− and Br− was 68% and 63%, respectively. Donnan exclusion appears to play an important role in determining rejection of BrO3− and Br−. In the presence of CaCl2, rejection of BrO3− and Br− ions was greatly reduced, confirming the importance of electrostatic interactions in determining rejection of BrO3− and Br−. The effect of Ca2+ is so pronounced that in most natural waters, rejection of both BrO3− and Br− by the membrane would be extremely small. PMID:23236251

  9. Action of pinaverium bromide, a calcium-antagonist, on gastrointestinal motility disorders.

    PubMed

    Christen, M O

    1990-01-01

    1. The evidence reviewed here indicates that pinaverium bromide (Dicetel) relaxes gastrointestinal (GI) structures primarily by inhibiting Ca2+ influx through potential-dependent channels of surface membranes of smooth muscle cells. 2. The in vivo selectivity of pinaverium bromide for the GI tract appears to be due mainly to its pharmacokinetic properties. Because of its low absorption (typical for quaternary ammonium compounds) and marked hepatobiliary excretion, most of the orally-administered dose of pinaverium bromide remains in the GI tract. 3. Orally-administered pinaverium bromide does not elicit adverse cardiovascular side-effects at doses that effectively relieve GI spasm, pain, transit disturbances and other symptoms related to motility disorders. 4. Pinaverium bromide is the only Ca2(+)-antagonist with known therapeutic efficacy in the treatment of irritable bowel syndrome and certain other functional intestinal disorders. PMID:2177709

  10. Comparative mobility of sulfonamides and bromide tracer in three soils

    USGS Publications Warehouse

    Kurwadkar, S.T.; Adams, C.D.; Meyer, M.T.; Kolpin, D.W.

    2011-01-01

    In animal agriculture, sulfonamides are one of the routinely used groups of antimicrobials for therapeutic and sub-therapeutic purposes. It is observed that, the animals when administered the antimicrobials, often do not completely metabolize them; and excrete the partially metabolized forms into the environment. Due to the continued use of antimicrobials and disposal of untreated waste, widespread occurrence of partially metabolized antimicrobials in aquatic and terrestrial environments has been reported in various scientific journals. In this research, the mobility of two sulfonamides - sulfamethazine (SMN), sulfathiazole (STZ) and a conservative bromide tracer was investigated in three soils collected from regions in the United States with large number of concentrated animal-feed operations. Results of a series of column studies indicate that the mobility of these two sulfonamides was dependent on pH, soil charge density, and contact time. At low pH and high charge density, substantial retention of sulfonamides was observed in all three soils investigated, due to the increased fraction of cationic and neutral forms of the sulfonamides. Conversely, enhanced mobility was observed at high pH, where the sulfonamides are predominantly in the anionic form. The results indicate that when both SMN and STZ are predominantly in anionic forms, their mobility approximates the mobility of a conservative bromide tracer. This observation is consistent for the mobility of both SMN and STZ individually, and also in the presence of several other antimicrobials in all three soils investigated. Higher contact time indicates lower mobility due to increased interaction with soil material. ?? 2011.

  11. An Eco-Friendly Ultrasound-Assisted Synthesis of Novel Fluorinated Pyridinium Salts-Based Hydrazones and Antimicrobial and Antitumor Screening

    PubMed Central

    Rezki, Nadjet; Al-Sodies, Salsabeel A.; Aouad, Mohamed R.; Bardaweel, Sanaa; Messali, Mouslim; El Ashry, El Sayed H.

    2016-01-01

    The present work reports an efficient synthesis of fluorinated pyridinium salts-based hydrazones under both conventional and eco-friendly ultrasound procedures. The synthetic approach first involves the preparation of halogenated pyridinium salts through the condensation of isonicotinic acid hydrazide (1) with p-fluorobenzaldehyde (2) followed by the nucleophilic alkylation of the resulting N-(4-fluorobenzylidene)isonicotinohydrazide (3) with a different alkyl iodide. The iodide counteranion of 5–10 was subjected to an anion exchange metathesis reaction in the presence of an excess of the appropriate metal salts to afford a new series of fluorinated pyridinium salts tethering a hydrazone linkage 11–40. Ultrasound irradiation led to higher yields in considerably less time than the conventional methods. The newly synthesized ILs were well-characterized with FT-IR, 1H NMR, 13C NMR, 11B, 19F, 31P and mass spectral analyses. The ILs were also screened for their antimicrobial and antitumor activities. Within the series, the salts tethering fluorinated counter anions 11–13, 21–23, 31–33 and 36–38 were found to be more potent against all bacterial and fungal strains at MIC 4–8 µg/mL. The in vitro antiproliferative activity was also investigated against four tumor cell lines (human ductal breast epithelial tumor T47D, human breast adenocarcinoma MCF-7, human epithelial carcinoma HeLa and human epithelial colorectal adenocarcinoma Caco-2) using the MTT assay, which revealed that promising antitumor activity was exhibited by compounds 5, 12 and 14. PMID:27213367

  12. An Eco-Friendly Ultrasound-Assisted Synthesis of Novel Fluorinated Pyridinium Salts-Based Hydrazones and Antimicrobial and Antitumor Screening.

    PubMed

    Rezki, Nadjet; Al-Sodies, Salsabeel A; Aouad, Mohamed R; Bardaweel, Sanaa; Messali, Mouslim; El Ashry, El Sayed H

    2016-01-01

    The present work reports an efficient synthesis of fluorinated pyridinium salts-based hydrazones under both conventional and eco-friendly ultrasound procedures. The synthetic approach first involves the preparation of halogenated pyridinium salts through the condensation of isonicotinic acid hydrazide (1) with p-fluorobenzaldehyde (2) followed by the nucleophilic alkylation of the resulting N-(4-fluorobenzylidene)isonicotinohydrazide (3) with a different alkyl iodide. The iodide counteranion of 5-10 was subjected to an anion exchange metathesis reaction in the presence of an excess of the appropriate metal salts to afford a new series of fluorinated pyridinium salts tethering a hydrazone linkage 11-40. Ultrasound irradiation led to higher yields in considerably less time than the conventional methods. The newly synthesized ILs were well-characterized with FT-IR, ¹H NMR, (13)C NMR, (11)B, (19)F, (31)P and mass spectral analyses. The ILs were also screened for their antimicrobial and antitumor activities. Within the series, the salts tethering fluorinated counter anions 11-13, 21-23, 31-33 and 36-38 were found to be more potent against all bacterial and fungal strains at MIC 4-8 µg/mL. The in vitro antiproliferative activity was also investigated against four tumor cell lines (human ductal breast epithelial tumor T47D, human breast adenocarcinoma MCF-7, human epithelial carcinoma HeLa and human epithelial colorectal adenocarcinoma Caco-2) using the MTT assay, which revealed that promising antitumor activity was exhibited by compounds 5, 12 and 14. PMID:27213367

  13. Excited triplet state of N-(9-methylpurin-6-yl)pyridinium cation as an efficient photosensitizer in the oxidation of sulfur-containing amino acids. Laser flash and steady-state photolysis studies

    SciTech Connect

    Marciniak, B. Univ. of Notre Dame, IN ); Hug, G.L.; Bobrowski, K. ); Rozwadowski, J. )

    1995-01-11

    In this paper, we present and discuss the results of a detailed mechanistic study of the photosensitized oxidation of sulfur-containing amino acids by N-(9-methylpurin-6-yl)pyridinium cations in aqueous solution. The results provide data on the photoreactivity of the pyridinium salts (derived from the purine bases) in the presence of the electron donors such as sulfur-containing organic compounds and give new experimental evidence for the general mechanism of the sensitized photooxidation of thioethers proposed previously. 39 refs., 6 figs., 2 tabs.

  14. 2-Methyl­pyridinium 5-(2,4-dinitro­phen­yl)-1,3-dimethyl­barbiturate

    PubMed Central

    Sridevi, Gunaseelan; Kalaivani, Doraisamyraja

    2012-01-01

    In the title mol­ecular salt [systematic name: 2-methyl­pyridinium 5-(2,4-dinitro­phen­yl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetra­hydro­pyrimidin-4-olate], C6H8N+·C12H9N4O7 −, the cation and anion are linked a through strong N—H⋯O hydrogen bond. In the crystal, C—H⋯O inter­actions link the ions, generating a chain along [010]. PMID:22589914

  15. Construction of tetracyclic 3-spirooxindole through cross-dehydrogenation of pyridinium: applications in facile synthesis of (±)-corynoxine and (±)-corynoxine B.

    PubMed

    Xu, Jun; Shao, Li-Dong; Li, Dashan; Deng, Xu; Liu, Yu-Chen; Zhao, Qin-Shi; Xia, Chengfeng

    2014-12-31

    A facile and straightforward method was developed to construct the fused tetracyclic 3-spirooxindole skeleton, which exists widely in natural products. The formation of the tetracyclic 3-spirooxindole structure was achieved through a transition-metal-free intramolecular cross-dehydrogenative coupling of pyridinium, which were formed in situ by the condensation of 3-(2-bromoethyl)indolin-2-one derivatives with 3-substituted pyridines. As examples of the application of this new methodology, two potentially medicinal natural products, (±)-corynoxine and (±)-corynoxine B, were efficiently synthesized in five scalable steps. PMID:25496352

  16. Modeling the [NTf2] pyridinium ionic liquids family and their mixtures with the soft statistical associating fluid theory equation of state.

    PubMed

    Oliveira, M B; Llovell, F; Coutinho, J A P; Vega, L F

    2012-08-01

    In this work, the soft statistical associating fluid theory (soft-SAFT) equation of state (EoS) has been used to provide an accurate thermodynamic characterization of the pyridinium-based family of ionic liquids (ILs) with the bis(trifluoromethylsulfonyl)imide anion [NTf(2)](-). On the basis of recent molecular simulation studies for this family, a simple molecular model was proposed within the soft-SAFT EoS framework. The chain length value was transferred from the equivalent imidazolium-based ILs family, while the dispersive energy and the molecular parameters describing the cation-anion interactions were set to constant values for all of the compounds. With these assumptions, an appropriate set of molecular parameters was found for each compound fitting to experimental temperature-density data at atmospheric pressure. Correlations for the nonconstant parameters (describing the volume of the IL) with the molecular weight were established, allowing the prediction of the parameters for other pyridiniums not included in the fitting. Then, the suitability of the proposed model and its optimized parameters were tested by predicting high-pressure densities and second-order thermodynamic derivative properties such as isothermal compressibilities of selected [NTf(2)] pyridinium ILs, in a large range of thermodynamic conditions. The surface tension was also provided using the density gradient theory coupled to the soft-SAFT equation. Finally, the soft-SAFT EoS was applied to describe the phase behavior of several binary mixtures of [NTf(2)] pyridinium ILs with carbon dioxide, sulfur dioxide, and water. In all cases, a temperature-independent binary parameter was enough to reach quantitative agreement with the experimental data. The description of the solubility of CO(2) in these ILs also allowed identification of a relation between the binary parameter and the molecular weight of the ionic liquid, allowing the prediction of the CO(2) + C(12)py[NTf(2)] mixture. The good

  17. The reactivity of phenancyl bromide under β-cyclodextrin as supramolecular catalyst: a computational survey.

    PubMed

    Wan, Yali; Wang, Xueye; Liu, Na

    2015-05-01

    Phenacyl bromide as one starting material in multicomponent reactions (MCRs) with β-cyclodextrin (β-CD) as catalyst can get an excellent yield in short reaction times. The interaction of β-CD with phenacyl bromide plays an important role in this process. This paper studies the complex of β-CD with phenacyl bromide using density functional theory (DFT) method. Energy is investigated to find out the lowest energy of two possible complexation models. Hydrogen bonds are researched on the basis of natural bonding orbital (NBO) analysis. The relative position between phenacyl bromide and β-CD is confirmed by (1)H nuclear magnetic resonance ((1)HNMR). The results of frontier molecular orbitals and charge distribution reveal that β-CD catalyst improves the reactivity and electrophilicity of phenacyl bromide, meanwhile, the carbonyl group of phenacyl bromide more easily gives a carbocationic intermediate in the presence of β-CD as catalyst. The reactivity of phenancyl bromide under β-CD as supramolecular catalysis is improved. PMID:25929992

  18. Mast Cells Release Chemokine CCL2 in Response to Parkinsonian Toxin 1-Methyl-4-Phenyl-Pyridinium (MPP(+)).

    PubMed

    Kempuraj, Duraisamy; Thangavel, Ramasamy; Fattal, Ranan; Pattani, Sagar; Yang, Evert; Zaheer, Smita; Santillan, Donna A; Santillan, Mark K; Zaheer, Asgar

    2016-05-01

    Microglial activation and release of inflammatory cytokines and chemokines are crucial events in neuroinflammation. Microglial cells interact and respond to other inflammatory cells such as T cells and mast cells as well as inflammatory mediators secreted from these cells. Recent studies have shown that neuroinflammation causes and accelerates neurodegenerative disease such as Parkinson's disease (PD) pathogenesis. 1-methyl-4-phenyl-pyridinium ion (MPP(+)), the active metabolite of neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine activates glial cells and mediate neurodegeneration through release of inflammatory mediators. We have shown that glia maturation factor (GMF) activates glia and induces neuroinflammation and neurodegeneration and that MPP(+) activates mast cells and release proinflammatory cytokines and chemokines. The chemokine (C-C motif) ligand 2 (CCL2) levels have been shown to be elevated and play a role in PD pathogenesis. In the present study, we analyzed if MPP(+) activates mouse and human mast cells to release chemokine CCL2. Mouse bone marrow-derived mast cells (BMMCs) and human umbilical cord blood-derived cultured mast cells (hCBMCs) were incubated with MPP(+) (10 µM) for 24 h and CCL2 levels were measured in the supernatant media by ELISA. MPP(+)-significantly induced CCL2 release from BMMCs and hCBMCs. Additionally, GMF overexpression in BMMCs obtained from wild-type mice released significantly more CCL2, while BMMCs obtained from GMF-deficient mice showed less CCL2 release. Further, we show that MPP(+)-induced CCL2 release was greater in BMMCs-astrocyte co-culture conditions. Uncoupling protein 4 (UCP4) which is implicated in neurodegenerative diseases including PD was detected in BMMCs by immunocytochemistry. Our results suggest that mast cells may play role in PD pathogenesis. PMID:26646004

  19. Solvent bandwidth dependence and band asymmetry features of charge-transfer transitions in N-pyridinium phenolates

    SciTech Connect

    Kjaer, A.M.; Ulstrup, J.

    1987-04-01

    They have investigated the shape of the solvatochromic absorption band for Betaine-26 2,4,6-triphenyl-N-(di-tert-butyl-4-hydroxyphenyl)pyridinium ion in a range of polar, apolar, protic, and aprotic solvents. Multiphonon band theory, including both molecular modes and a vibrationally dispersive solvent, indicates that the solvents fall in three categories: (1) The bandshape for polar, aprotic solvents is well reproduced by that for a structureless continuous dielectric and a single high-frequency molecular mode. Solvent broadening correlates with epsilon/sub o//sup -1/ - epsilon/sub s//sup -1/, epsilon/sub o/ being the optical and epsilon/sub s/ the static dielectric constant. The molecular frequency, Omega/sub c/, and displacement, ..delta../sub c/, are not very solvent dependent, emphasizing their molecular character, and the value Omega/sub c/ approx. = 1600 cm/sup -1/ suggests that C-O, C-N, and C-C stretching is involved. (2) Bands for apolar, aprotic solvents correspond to the same model. Omega/sub c/ and ..delta../sub c/ are again not very solvent dependent and coincide with the values for polar aprotic solvents. The solvent broadening is solvent independent, and wider than that for a structureless dielectric. This points to multipolar, dispersive, pressure, or pseudopotential forces as coupling mechanisms. (3) The bandshape for normal alcohols can only be produced by a model resting on two molecular modes and a vibrational high-frequency solvent tail. Broadening, asymmetry, molecular frequencies, and deuterium isotope effects trace the protic solvent spectral entanglement to coupling between betaine-26 and a local mode group with features of both O-H stretching and bending and of librational solvent motion.

  20. An ultrafast spectroscopic and quantum mechanical investigation of multiple emissions in push-pull pyridinium derivatives bearing different electron donors.

    PubMed

    Carlotti, B; Benassi, E; Cesaretti, A; Fortuna, C G; Spalletti, A; Barone, V; Elisei, F

    2015-08-28

    A joint experimental and theoretical approach, involving state-of-the-art femtosecond fluorescence up-conversion measurements and quantum mechanical computations including vibronic effects, was employed to get a deep insight into the excited state dynamics of two cationic dipolar chromophores (Donor-π-Acceptor(+)) where the electron deficient portion is a N-methyl pyridinium and the electron donor a trimethoxyphenyl or a pyrene, respectively. The ultrafast spectroscopic investigation, and the time resolved area normalised emission spectra in particular, revealed a peculiar multiple emissive behaviour and allowed the distinct emitting states to be remarkably distinguished from solvation dynamics, occurring in water in a similar timescale. The two and three emissions experimentally detected for the trimethoxyphenyl and pyrene derivatives, respectively, were associated with specific local emissive minima in the potential energy surface of S1 on the ground of quantum-mechanical calculations. A low polar and planar Locally Excited (LE) state together with a highly polar and Twisted Intramolecular Charge Transfer (TICT) state is identified to be responsible for the dual emission of the trimethoxyphenyl compound. Interestingly, the more complex photobehaviour of the pyrenyl derivative was explained considering the contribution to the fluorescence coming not only from the LE and TICT states but also from a nearly Planar Intramolecular Charge Transfer (PICT) state, with both the TICT and the PICT generated from LE by progressive torsion around the quasi-single bond between the methylpyridinium and the ethene bridge. These findings point to an interconversion between rotamers for the pyrene compound taking place in its excited state against the Non-equilibrated Excited Rotamers (NEER) principle. PMID:26213993

  1. Methyl bromide emissions from a covered field: I. Experimental conditions and degradation in soil

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.

    1996-01-01

    An experiment is described to investigate the environmental fate and transport of methyl bromide in agricultural systems. The experiment was designed to determine the dynamics of methyl bromide movement through soil, degradation, and total emissions to the atmosphere. This is of particular interest because it will allow an assessment of the environmental impacts (i.e., stratospheric ozone depletion) resulting from the agricultural use of methyl bromide. Methyl bromide was applied at a rate of 843 kg in a 3.5-ha (i.e., 240 kg/ha) field at a depth of 0.25 m and covered with a sheet of 1-mil polyethylene plastic. The maximum methyl bromide concentration in the atmosphere occurred at night between 0200 and 0600 h. During the first 3 d of the experiment, the maximum daily concentrations at 0.2 m above the soil surface were 30, 5, and 1 mg/(m{sup 3} of air), respectively. The trend of reduced emissions with time continued until the plastic was removed, when a momentary increase in the methyl bromide emissions occurred. The maximum soil gas concentration 24 h after injection was 30 g/m{sup 3} located at a 0.25-m depth. When the plastic was removed from the field (at 5.6 d), the maximum soil gas concentration was approximately 2 g/m{sup 3} at a 0.5-m depth. A mass-difference method for estimating the total methyl bromide emissions from the soil, based on degradation of methyl bromide to Br{sup -}, indicates that approximately 39% or 325 kg ({+-} 164 kg) of the applied methyl bromide was converted to Br{sup -} and, therefore, 61% or 518 kg ({+-} 164 kg) was lost via volatilization. 16 refs., 11 figs., 2 tabs.

  2. Palladium-Catalyzed Alkoxycarbonylation of Unactivated Secondary Alkyl Bromides at Low Pressure.

    PubMed

    Sargent, Brendon T; Alexanian, Erik J

    2016-06-22

    Catalytic carbonylations of organohalides are important C-C bond formations in chemical synthesis. Carbonylations of unactivated alkyl halides remain a challenge and currently require the use of alkyl iodides under harsh conditions and high pressures of CO. Herein we report a palladium-catalyzed alkoxycarbonylation of secondary alkyl bromides that proceeds at low pressure (2 atm CO) under mild conditions. Preliminary mechanistic studies are consistent with a hybrid organometallic-radical process. These reactions efficiently deliver esters from unactivated alkyl bromides across a diverse range of substrates and represent the first catalytic carbonylations of alkyl bromides with carbon monoxide. PMID:27267421

  3. The action of structural analogues of ethidium bromide on the mitochondrial genome of yeast.

    PubMed

    Hall, R M; Mattick, J S; Nagley, P; Cobon, G S; Eastwood, F W; Linnane, A W

    1977-12-01

    We have studied the effects on the yeast mitochondrial genome of four analogues of ethidium bromide, in which the phenyl moieyt has been replaced by linear alkyl chains of lengths varying from seven to fifteen carbon atoms. These analogues are more efficient than ethidium bromide in inducing petite mutants in Saccharomyces cervisiae. The drugs also cause a loss of mtDNA from the cells in vivo; however these analogues are in fact less effective inhibitors of mitochondrial DNA replication per se, as shown by direct in vitro studies. It is concluded that these analogues are more efficient than ethidium bromide in causing the fragmentation of mitochondrial DNA in S. cervisiae. PMID:339057

  4. Solar energy storage using surfactant micelles

    NASA Astrophysics Data System (ADS)

    Srivastava, R. C.; Marwadi, P. R.; Latha, P. K.; Bhise, S. B.

    1982-09-01

    The results of experiments designed to test the soluble reduced form of thionine dye as a suitable solar energy storage agent inside the hydrophobic core of surfactant micelles are discussed. Aqueous solutions of thionine, methylene blue, cetyl pyridinium bromide, sodium lauryl sulphate, iron salts, and iron were employed as samples of anionic, cationic, and nonionic surfactants. The solutions were exposed to light until the dye disappeared, and then added drop-by-drop to surfactant solutions. The resultant solutions were placed in one cell compartment while an aqueous solution with Fe(2+) and Fe(3+) ions were placed in another, with the compartments being furnished with platinum electrodes connected using a saturated KCl-agar bridge. Data was gathered on the short circuit current, maximum power, and internal resistance encountered. Results indicate that dye-surfactant systems are viable candidates for solar energy storage for later conversion to electrical power.

  5. Evaluation of alkali bromide salts for potential pyrochemical applications

    SciTech Connect

    Tripathy, P.K.; Gutknecht, T.Y.; Herrmann, S.D.; Fredrickson, G.L.; Lister, T.E.

    2013-07-01

    Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr{sub 3} (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973 K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673 K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electro-deposit high purity RE metals at comparatively lower operating temperatures. (authors)

  6. Water-lithium bromide double-effect absorption cooling analysis

    NASA Astrophysics Data System (ADS)

    Vliet, G. C.; Lawson, M. B.; Lithgow, R. A.

    1980-12-01

    A numerical model was developed for the transient simulation of the double-effect, water-lithium bromide absorption cooling machine and was used to determine the effect of the various design and input variables on the absorption unit performance. The performance parameters considered were coefficient of performance and cooling capacity. The variables considered include source hot water, cooling water, and chilled water temperatures; source hot water, cooling water, and chilled water flow rates; solution circulation rate; heat exchanger areas; pressure drop between evaporator and absorber; solution pump characteristics; and refrigerant flow control methods. The performance sensitivity study indicates that the distribution of heat exchanger area among the various (seven) heat exchange components is a very important design consideration. Moreover, it indicated that the method of flow control of the first effect refrigerant vapor through the second effect is a critical design feature when absorption units operate over a significant range of cooling capacity. The model was used to predict the performance of the Trane absorption unit with fairly good accuracy.

  7. [Treatment of cetyltrimethyl ammonium bromide wastewater by potassium ferrate].

    PubMed

    Yang, Wei-hua; Wang, Hong-hui; Zeng, Xiao-xu; Huang, Ting-ting

    2009-08-15

    A novel oxidant potassium ferrate (K2FeO4) was used to remove cetyltrimethyl ammonium bromide (CTAB) at room temperature. The effects of various conditions on the removal ratio, such as reaction time, dosing quantity of K2FeO4 and initial pH, were investigated. The experiments results show that the removal ratio reaches 79.4% when the reaction time is 30 min, the dosing quantity of K2FeO4 to CTAB is 1:1, the initial pH of the solution is 7. In the reaction progress, the oxidation of K2FeO4 and the flocculation of the reduction product have synergistic effect on the removal of CTAB. In addition, infrared spectra of CTAB before and after being treated with K2FeO4 were further studied. The results indicate that the degradation process involves the interruption of chain and the subsequent mineralization to inorganic molecules. Furthermore, the reaction of K2FeO4 and CTAB follows second order kinetics law. PMID:19799287

  8. Structural and electronic properties of Diisopropylammonium bromide molecular ferroelectric crystal

    NASA Astrophysics Data System (ADS)

    Alsaad, A.; Qattan, I. A.; Ahmad, A. A.; Al-Aqtash, N.; Sabirianov, R. F.

    2015-10-01

    We report the results of ab-initio calculations based on Generalized Gradient Approximation (GGA) and hybrid functional (HSE06) of electronic band structure, density of states and partial density of states to get a deep insight into structural and electronic properties of P21 ferroelectric phase of Diisopropylammonium Bromide molecular crystal (DIPAB). We found that the optical band gap of the polar phase of DIPAB is ∼ 5 eV confirming it as a good dielectric. Examination of the density of states and partial density of states reveal that the valence band maximum is mainly composed of bromine 4p orbitals and the conduction band minimum is dominated by carbon 2p, carbon 2s, and nitrogen 2s orbitals. A unique aspect of P21 ferroelectric phase is the permanent dipole within the material. We found that P21 DIPAB has a spontaneous polarization of 22.64 consistent with recent findings which make it good candidate for the creation of ferroelectric tunneling junctions (FTJs) which have the potential to be used as memory devices.

  9. 4-Bromophenacyl Bromide Specifically Inhibits Rhoptry Secretion during Toxoplasma Invasion

    PubMed Central

    Ravindran, Sandeep; Lodoen, Melissa B.; Verhelst, Steven H. L.; Bogyo, Matthew; Boothroyd, John C.

    2009-01-01

    Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known about the mechanism of secretion of any Toxoplasma protein into the host cell. We used a chemical inhibitor of phospholipase A2s, 4-bromophenacyl bromide (4-BPB), to look at the role of such lipases in the secretion of Toxoplasma proteins. We found that 4-BPB was a potent inhibitor of rhoptry secretion in Toxoplasma invasion. This drug specifically blocked rhoptry secretion but not microneme secretion, thus effectively showing that the two processes can be de-coupled. It affected parasite motility and invasion, but not attachment or egress. Using propargyl- or azido-derivatives of the drug (so-called click chemistry derivatives) and a series of 4-BPB-resistant mutants, we found that the drug has a very large number of target proteins in the parasite that are involved in at least two key steps: invasion and intracellular growth. This potent compound, the modified “click-chemistry” forms of it, and the resistant mutants should serve as useful tools to further study the processes of Toxoplasma early invasion, in general, and rhoptry secretion, in particular. PMID:19956582

  10. 4-Bromophenacyl bromide specifically inhibits rhoptry secretion during Toxoplasma invasion.

    PubMed

    Ravindran, Sandeep; Lodoen, Melissa B; Verhelst, Steven H L; Bogyo, Matthew; Boothroyd, John C

    2009-01-01

    Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa that is able to infect a wide variety of host cells. During its active invasion process it secretes proteins from discrete secretory organelles: the micronemes, rhoptries and dense granules. Although a number of rhoptry proteins have been shown to be involved in important interactions with the host cell, very little is known about the mechanism of secretion of any Toxoplasma protein into the host cell. We used a chemical inhibitor of phospholipase A2s, 4-bromophenacyl bromide (4-BPB), to look at the role of such lipases in the secretion of Toxoplasma proteins. We found that 4-BPB was a potent inhibitor of rhoptry secretion in Toxoplasma invasion. This drug specifically blocked rhoptry secretion but not microneme secretion, thus effectively showing that the two processes can be de-coupled. It affected parasite motility and invasion, but not attachment or egress. Using propargyl- or azido-derivatives of the drug (so-called click chemistry derivatives) and a series of 4-BPB-resistant mutants, we found that the drug has a very large number of target proteins in the parasite that are involved in at least two key steps: invasion and intracellular growth. This potent compound, the modified "click-chemistry" forms of it, and the resistant mutants should serve as useful tools to further study the processes of Toxoplasma early invasion, in general, and rhoptry secretion, in particular. PMID:19956582

  11. Associated anisotropy decays of ethidium bromide interacting with DNA

    NASA Astrophysics Data System (ADS)

    Chib, Rahul; Raut, Sangram; Sabnis, Sarika; Singhal, Preeti; Gryczynski, Zygmunt; Gryczynski, Ignacy

    2014-03-01

    Ethidium Bromide (EB) is a commonly used dye in a deoxyribonucleic acid (DNA) study. Upon an intercalation, this dye significantly increases its brightness and fluorescence lifetime. In this report we have studied the time resolved fluorescence properties of EB existing simultaneously in free and DNA-bound forms in the solution. Fluorescence intensity decays were fitted globally to a double exponential model with lifetimes corresponding to free (1.6 ns) and bound (22 ns) forms, and molar fractions were determined for all used solutions. Anisotropy decays displayed characteristic time dependence with an initial rapid decline followed by recovery and slow decay. The short-lived fraction associated with free EB molecules decreases faster than long-lived fraction associated with EB bound to DNA. Consequently, contribution from fast rotation leads to initial rapid decay in anisotropy. On the other hand bound fraction, due to slow rotation helps recover anisotropy in time. This effect of associated anisotropy decays in systems such as EB free/EB-DNA is clearly visible in a wide range of concentrations, and should be taken into account in polarization assays and biomolecule dynamics studies.

  12. Fabrication of double-sided thallium bromide strip detectors

    NASA Astrophysics Data System (ADS)

    Hitomi, Keitaro; Nagano, Nobumichi; Onodera, Toshiyuki; Kim, Seong-Yun; Ito, Tatsuya; Ishii, Keizo

    2016-07-01

    Double-sided strip detectors were fabricated from thallium bromide (TlBr) crystals grown by the traveling-molten zone method using zone-purified materials. The detectors had three 3.4-mm-long strips with 1-mm widths and a surrounding electrode placed orthogonally on opposite surfaces of the crystals at approximately 6.5×6.5 mm2 in area and 5 mm in thickness. Excellent charge transport properties for both electrons and holes were observed from the TlBr crystals. The mobility-lifetime products for electrons and holes in the detector were measured to be ~3×10-3 cm2/V and ~1×10-3 cm2/V, respectively. The 137Cs spectra corresponding to the gamma-ray interaction position were obtained from the detector. An energy resolution of 3.4% of full width at half maximum for 662-keV gamma rays was obtained from one "pixel" (an intersection of the strips) of the detector at room temperature.

  13. Locations of Bromide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions have been shown to play a dominant role in the crystallization of chicken egg-white lysozyme from salt solutions. Previous studies employing X-ray crystallography have found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystals grown in bromide and chloride solutions. Five possible anion-binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four further sites were found which corresponded to the four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion-binding sites in lysozyme remain unchanged even when different anions and different crystal forms of lysozyme are employed.

  14. Fluorometric Determination of Deoxyribonucleic Acid in Bacteria with Ethidium Bromide

    PubMed Central

    Donkersloot, J. A.; Robrish, S. A.; Krichevsky, M. I.

    1972-01-01

    A simple, sensitive, and rapid method is presented for the determination of deoxyribonucleic acid (DNA) in both gram-positive and gram-negative bacteria. It is based upon the fluorometric determination of DNA with ethidium bromide after alkaline digestion of the bacteria to hydrolyze the interfering ribonucleic acid. The assay takes less than 2 hr. Its sensitivity is at least 0.2 μg of DNA in a final solution of 4 ml and it uses commonly available filter or double monochromator fluorometers. Judicious choice of light source and filters allows an additional 10-fold increase in sensitivity with a filter fluorometer. Turbidity caused by bacteria or insoluble polysaccharides does not interfere with the fluorescence measurements. There was no significant difference between the results obtained with this method and those obtained with the indole and diphenylamine methods when these assays were applied to Escherichia coli and sucrose- or glucose-grown Streptococcus mutans. The method was also tested by determining the specific growth rate of E. coli. This new procedure should be especially useful for the determination of bacterial DNA in dilute suspensions and for the estimation of bacterial growth or DNA replication where more conventional methods are not applicable or sensitive enough. PMID:4561101

  15. Chloride, bromide and iodide scintillators with europium doping

    DOEpatents

    Zhuravleva, Mariya; Yang, Kan

    2014-08-26

    A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has been studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.

  16. Bacterial oxidation of methyl bromide in Mono Lake, California

    USGS Publications Warehouse

    Connell, T.L.; Joye, S.B.; Miller, L.G.; Oremland, R.S.

    1997-01-01

    The oxidation of methyl bromide (MeBr) in the water column of Mono Lake, CA, was studied by measuring the formation of H14CO3 from [14C]MeBr. Potential oxidation was detected throughout the water column, with highest rates occurring in the epilimnion (5-12 m depth). The oxidation of MeBr was eliminated by filter-sterilization, thereby demonstrating the involvement of bacteria. Vertical profiles of MeBr activity differed from those obtained for nitrification and methane oxidation, indicating that MeBr oxidation is not simply a co-oxidation process by either nitrifiers or methanotrophs. Furthermore, specific inhibitors of methane oxidation and/or nitrification (e.g., methyl fluoride, acetylene, allyl sulfide) had no effect upon the rate of MeBr oxidation in live samples. Of a variety of potential electron donors added to Mono Lake water, only trimethylamine resulted in the stimulation of MeBr oxidation. Cumulatively, these results suggest that the oxidation of MeBr in Mono Lake waters is attributable to trimethylamine-degrading methylotrophs. Neither methyl chloride nor methanol inhibited the oxidation of [14C]MeBr in live samples, indicating that these bacteria directly oxidized MeBr rather than the products of MeBr nucleophilic substitution reactions.

  17. Bioreactors for removing methyl bromide following contained fumigations

    USGS Publications Warehouse

    Miller, L.G.; Baesman, S.M.; Oremland, R.S.

    2003-01-01

    Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (> 110 ??mol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell densities in the bioreactor using MeBr as its sole carbon and energy source. Bacterial oxidation of MeBr produced CO2 and hydrobromic acid (HBr), which required continuous neutralization with NaOH for the system to operate effectively. Strain IMB-1 was capable of sustained oxidation of large amounts of MeBr (170 mmol in 46 d). In an open-system bioreactor (10-L fermenter), strain IMB-1 oxidized a continuous supply of MeBr (220 ??mol L-1 in air). Growth was continuous, and 0.5 mol of MeBr was removed from the air supply in 14 d. The specific rate of MeBr oxidation was 7 ?? 10-16 mol cell-1 h-1. Bioreactors such as these can therefore be used to remove large quantities of contaminant MeBr, which opens the possibility of biodegradation as a practical means for its disposal.

  18. Atmospheric methyl bromide: Trends and global mass balance

    SciTech Connect

    Khalil, M.A.K.; Rasmussen, R.A.; Gunawardena, R. )

    1993-02-20

    Atmospheric methyl bromide is of considerable environmental importance as the largest reservoir of gaseous bromine in the atmosphere. Bromine gases can catalytically destroy stratospheric ozone. Since agricultural activities, automobiles, biomass burning, and other human activities produce CH[sub 3]Br, it is of interest to know its global mass balance and particularly the specific sources and sinks. In this paper the authors provide a decadal time series of global CH[sub 3]Br concentrations in the Earth's atmosphere. The data show that average concentrations are about 10 pptv and during the last 4 years may be increasing at 0.3 [plus minus] 0.1 pptv/yr (3%/yr [plus minus] 1%/yr). They estimate that the atmospheric lifetime of CH[sub 3]Br that is due to reaction with OH, is about 2 years, resulting in a calculated global emission rate of about 100 Gy/yr. Ocean supersaturations of 140-180% are observed, and atmospheric concentrations over the open oceans are higher than at comparably located coastal sites. The ocean source is estimated to be about 35 Gg/yr. The remaining emissions must come from other natural sources and anthropogenic activities. The results are based on some 2,200 samples obtained over more than a decade. Mass balance calculations explain most aspects of the present data but other implications are not easily reconciled, leaving open the possibility of undiscovered sources and sinks. 20 refs., 5 figs., 4 tabs.

  19. Polarization effects in thallium bromide x-ray detectors

    SciTech Connect

    Kozorezov, A.; Wigmore, J. K.; Gostilo, V.; Shorohov, M.; Owens, A.; Quarati, F.; Webb, M. A.

    2010-09-15

    We present the results of a detailed experimental study of polarization effects in thallium bromide planar x-ray detectors. Measurements were carried out in the range 10-100 keV by scanning a highly focused x-ray beam, 50 {mu}m in diameter, from a synchrotron source across the detector. Above a certain radiation threshold the detector response showed a systematic degradation of its spectroscopic characteristics, peak channel position, peak height, and energy resolution. Using a pump-and-probe technique, we studied the dynamics of spectral degradation, the spatial extent and relaxation of the polarized region, and the dependence of the detector response on bias voltage and temperature. For comparison, we modeled polarization effects induced by the charging of traps by both electrons and holes using a model based on recent theoretical work of Bale and Szeles. We calculated the charge collection efficiency and spectral line shapes as functions of exposure time, beam position, count rate, and photon energy, and obtained credible agreement with experimental results.

  20. Nanocapsules of perfluorooctyl bromide for theranostics: from formulation to targeting

    NASA Astrophysics Data System (ADS)

    Diou, O.; Fattal, E.; Payen, T.; Bridal, S. L.; Valette, J.; Tsapis, N.

    2014-03-01

    The need to detect cancer at its early stages, as well as, to deliver chemotherapy to targeted site motivates many researchers to build theranostic platforms which combine diagnostic and therapy. Among imaging modalities, ultrasonography and Magnetic Resonance Imaging (MRI) are widely available, non invasive and complement each other. Both techniques often require the use of contrast agents. We have developed nanocapsules of perfluorooctyl bromide as dual contrast agent for both imaging modalities. The soft, amorphous polymer shell provides echogenicity, while the high-density perfluorinated liquid core allows detection by 19F MRI. We have used a shell of poly(lactide-co-glycolide) (PLGA) since this polymer is biodegradable, biocompatible and can be loaded with drugs. These capsules were shown to be efficient in vitro as contrast agents for both 19F MRI and ultrasonography. In addition, for in vivo applications a poly(ethyleneglycol) (PEG) coating promotes stability and prolonged circulation. Being stealth, nanocapsule can accumulate passively into implanted tumors by the EPR effect. We will present nanocapsule formulation and characterization, and will show promising in vivo results obtained for both ultrasonography and 19F MRI.

  1. Improved spectrometric characteristics of thallium bromide nuclear radiation detectors

    NASA Astrophysics Data System (ADS)

    Hitomi, K.; Murayama, T.; Shoji, T.; Suehiro, T.; Hiratate, Y.

    1999-06-01

    Thallium bromide (TlBr) is a compound semiconductor with a high atomic number and wide band gap. In this study, nuclear radiation detectors have been fabricated from the TlBr crystals. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using the materials purified by many pass zone refining. The crystals were characterized by measuring the resistivity, the mobility-lifetime ( μτ) product and the energy required to create an electron-hole pair (the ɛ value). Improved energy resolution has been obtained by the TlBr radiation detectors. At room temperature the full-width at half-maximum (FWHM) for the 59.5, 122 and 662 keV γ-ray photo peak obtained from the detectors were 3.3, 8.8 and 29.5 keV, respectively. By comparing the saturated peak position of the TlBr detector with that of the CdTe detector, the ɛ value has been estimated to be about 5.85 eV for the TlBr crystal.

  2. Evaluation of Alkali Bromide Salts for Potential Pyrochemical Applications

    SciTech Connect

    Prabhat K. Tripathy; Steven D. Herrmann; Guy L. Fredrickson; Tedd E. Lister; Toni Y. Gutknecht

    2013-10-01

    Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr3 (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electrodeposit high purity RE metals at comparatively lower operating temperatures.

  3. Reduced effect of bromide on the genotoxicity in secondary effluent of a municipal wastewater treatment plant during chlorination.

    PubMed

    Wu, Qian-Yuan; Li, Yi; Hu, Hong-Ying; Sun, Ying-Xue; Zhao, Feng-Yun

    2010-07-01

    Chlorination of wastewater can form genotoxic, mutagenic, and/or carcinogenic disinfection byproduct (DBPs). In this study, the effect of bromide on genotoxicity in secondary effluent of a municipal wastewater treatment plant during chlorination was evaluated by the SOS/umu test. The presence of bromide notably decreased the genotoxicity in secondary effluent during chlorination, especially under conditions of high ammonia concentration. Bromide significantly decreased the concentration of ofloxacin, a genotoxic chemical in secondary effluent, during chlorination with high concentration of ammonia, while genotoxic DBPs formation of humic acid and aromatic amino acids associated with bromide limitedly contributed to the changes of genotoxicity in secondary effluent under the conditions of this study. By fractionating dissolved organic matter (DOM) in the secondary effluent into different fractions, the fractions containing hydrophilic substances (HIS) and hydrophobic acids (HOA) contributed to the decrease in genotoxicity induced by bromide. Chlorination of HOA without bromide increased genotoxicity, while the addition of bromide decreased genotoxicity. PMID:20521844

  4. Highly solid-state emissive pyridinium-substituted tetraphenylethylene salts: emission color-tuning with counter anions and application for optical waveguides.

    PubMed

    Hu, Fang; Zhang, Guanxin; Zhan, Chi; Zhang, Wei; Yan, Yongli; Zhao, Yongsheng; Fu, Hongbing; Zhang, Deqing

    2015-03-18

    In this paper seven salts of pyridinium-substituted tetraphenylethylene with different anions are reported. They show typical aggregation-induced emission. Crystal structures of three of the salts with (CF(3)SO(2))(2) N(-), CF(3) SO(3)(-), and SbF(6)(-) as the respective counter anions, are determined. The emission behavior of their amorphous and crystalline solids is investigated. Both amorphous and crystalline solids, except for the one with I(-), are highly emissive. Certain amorphous solids are red-emissive with almost the same quantum yields and fluorescence life-times. However, some crystalline solids are found to show different emission colors varying from green to yellow. Thus, their emission colors can be tuned by the counter anions. Furthermore, certain crystalline solids are highly emissive compared to the respective amorphous solids. Such solid-state emission behavior of these pyridinium-substituted tetraphenylethylene salts is interpreted on the basis of their crystal structures. In addition, optical waveguiding behavior of fabricated microrods is presented. PMID:25338963

  5. Voltammetry and conductivity of a polyether-pyridinium room temperature molten salt electrolyte and of its polymer electrolyte solutions in polydimethylsiloxane

    SciTech Connect

    Pyati, R.; Murray, R.W.

    1996-02-01

    This report describes the synthesis, microelectrode voltammetry, and ionic conductivity of a new room temperature molten salt N-(methoxy(ethoxy){sub 2}ethyl)pyridinium p-toluene sulfonate (abbreviated as[Py(E{sub 3}M){sup +}][Tos{sup {minus}}]) and of its solution in a hydroxy-terminated polydimethylsiloxane. Both ionically conductive liquids (conductivity = 1 {times} 10{sup {minus}4} {Omega}{sup {minus}1} cm{sup {minus}1}) exhibit voltammetric potential windows of about 1.5 V. The negative potential limit is determined by the reduction of the [Py(E{sub 3}M){sup +}] pyridinium species, with subsequent radical coupling to form a voltammetrically observed viologen dimer. The estimated diffusivities of the [Py(E{sub 3}M){sup +}] species, of a diethyleneglycol-tailed ferrocene redox solute studied, and by application of Nernst-Einstein relation to the ionic charge carriers, all lie in the 10{sup {minus}7} to 10{sup {minus}8} cm{sup 2}/s range. Viscosities and glass transition thermal observations are reported as is the fit of the temperature dependencies of ionic conductivity in [Py(E{sub 3}M){sup +}][Tos{sup {minus}}] and in [Py(E{sub 3}M){sup +}][TOS{sup {minus}}]/PDMS mixtures to Vogel-Tamman-Fulcher predictions.

  6. Crystal structure of bis­[4-(di­methyl­amino)­pyridinium] aqua­bis­(oxalato)oxidovanadate(IV) dihydrate

    PubMed Central

    Sehimi, Hiba; Chérif, Ichraf; Zid, Mohamed Faouzi

    2016-01-01

    The title organic–inorganic hybrid salt, (C7H11N2)2[V(C2O4)2O(H2O)]·2H2O, shows a distorted octa­hedral coordination environment for the vanadium(IV) atom in the anion (point group symmetry 2), with four O atoms from two symmetry-related chelating oxalate dianions and two O atoms in trans configuration from a coordinating water mol­ecule and a terminal vanadyl O atom. In the crystal, (001) layers of cations and anions alternate along [001]. The anionic layers are built up by inter­molecular O—H⋯O hydrogen bonds involving the coordinating and solvent water mol­ecules. The cationic layers are linked to the anionic layers via N—H⋯O hydrogen bonds between the pyridinium group and the non-coordinating O atoms of the oxalate group. The 4-(di­methyl­amino)­pyridinium cations are also engaged in π–π stacking with their anti­parallel neighbours [centroid-to-centroid distance = 3.686 (2) Å]. Considering all supra­molecular features, a three-dimensional network structure is accomplished. PMID:27555950

  7. Crystal structure of 2-{[2-(3-phenyl­allyl­idene)hydrazin-1-yl]thio­carbonyl­sulfanylmeth­yl}pyridinium chloride

    PubMed Central

    Low, May Lee; Ravoof, Thahira Begum S. A.; Tahir, Mohamed Ibrahim Mohamed; Crouse, Karen A.; Tiekink, Edward R. T.

    2014-01-01

    In the title salt of an S-substituted di­thio­carbazate, C16H16N3S2 +·Cl−, the dihedral angles between the almost planar (r.m.s deviation = 0.005 Å) central CN2S2 residue and the terminal pyridinium and phenyl rings are 80.09 (11) and 3.82 (11)°, respectively, indicating the cation has an L-shape; the amine H and thione S atoms are syn. The conformation about each of the imine [1.376 (3) Å] and ethene [1.333 (4) Å] bonds is E. The shortened C—C bond [1.444 (4) Å] linking the double bonds is consistent with conjugation in this part of the mol­ecule. In the crystal, supra­molecular layers with a jagged topology are formed by charged-assisted amine-H⋯Cl− and pyridinium-N+—H⋯Cl− hydrogen bonds. The layers stack along the a axis with no specific directional inter­actions between them. PMID:25484832

  8. BROMIDE'S EFFECT ON DBP FORMATION, SPECIATION, AND CONTROL: PART 1, OZONATION

    EPA Science Inventory

    The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection byproducts (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalometha...

  9. Palladium-catalyzed direct α-arylation of methyl sulfones with aryl bromides.

    PubMed

    Zheng, Bing; Jia, Tiezheng; Walsh, Patrick J

    2013-04-01

    A direct and efficient approach for palladium-catalyzed arylation of aryl and alkyl methyl sulfones with aryl bromides has been developed. The catalytic system affords arylated sulfones in good to excellent yields (73-90%). PMID:23517309

  10. Electrochemical removal of bromide and reduction of THM formation potential in drinking water.

    PubMed

    Kimbrough, David Eugene; Suffet, I H

    2002-11-01

    Trihalomethanes (THMs), a by-product of the chlorination of natural waters containing dissolved organic carbon and bromide, are the focus of considerable public health concern and regulation due to their potential as a carcinogen by ingestion. This paper presents a promising new water treatment process that lowers the concentration of bromide in drinking water and thus, lowers the THM formation potential. Bromide is oxidized by electrolysis to bromine and then the bromine apparently volatilized. The electrolyzed water, when chlorinated, produces measurably lower amounts of THMs and proportionately fewer brominated THMs, which are of greater public health concern than the chlorinated THMs. Removing bromide should also reduce the formation of other disinfection by-products such as bromate and haloacetic acids. PMID:12448534

  11. Factors affecting performance of methyl bromide alternatives - a South Atlantic perspective

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumigant application methods and equipment were identified as a source of variability in the performance of methyl bromide alternatives during several field demonstration trials conducted in 2007. Shank injection systems incorrectly modified to accommodate reduced fumigant flow rates through deliv...

  12. CHLORPYRIFOS TRANSFORMATION BY AQUEOUS CHLORINE IN THE PRESENCE OF BROMIDE AND NATURAL ORGANIC MATTER

    EPA Science Inventory

    The aqueous chlorination of chlorpyrifos (CP) was investigated in the presence of bromide and natural organic matter (NOM), which were identified as naturally occurring aqueous constituents that could impact CP transformation rates to the toxic product chlorpyrifos oxon (CPO). Br...

  13. Uptake and excretion of ( UC)methyl bromide as influenced by exposure concentration

    SciTech Connect

    Medinsky, M.A.; Dutcher, J.S.; Bond, J.A.; Henderson, R.F.; Mauderly, J.L.; Snipes, M.B.; Mewhinney, J.A.; Cheng, Y.S.; Birnbaum, L.S.

    1985-01-01

    Uptake of methyl bromide and pathways for excretion of UC were investigated in male Fischer-344 rats after nose-only inhalation of 50, 300, 5700, or 10,400 nmol (1.6 to 310 ppm) of ( UC)methyl bromide/liter of air for 6 hr. Fractional uptake of methyl bromide decreased at the highest concentrations, 5700 and 10,400 nmol/liter, with 37 and 27% of the inhaled methyl bromide absorbed, respectively, compared to 48% at the lower levels. Total methyl bromide absorbed was 9 or 40 mol/kg body wt after exposure to 50 or 300 nmol/liter, respectively. Elimination of UC was linearly related to the amount of methyl bromide absorbed as determined from urine, feces, expired CO2, and parent compound collected for 66 hr after the end of exposure. Exhaled UCO2 was the dominant route of excretion, with from 1.2 to 110 mol (50% of amount absorbed) exhaled, and was described by a two-component negative exponential function; 85% was exhaled with t1/2 of 4 hr, and the remaining 15% was exhaled with a t1/2 of 17 hr. The rate of exhalation of UCO2 was not affected by the amount of ( UC)methyl bromide absorbed. From 0.4 to 54 mol was excreted in urine (20% of amount absorbed). The half-time for excretion of UC in urine was approximately 10 hr, and the rate of excretion was not dependent on the amount of ( UC)methyl bromide absorbed. Little UC was exhaled as methyl bromide (<4% of the dose) or excreted in feces (<2%). At the end of 66 hr, 25% of the UC absorbed remained in the rats. Liver, kidneys, adrenals, lungs, thymus, and turbinates (maxilloturbinates, ethmoturbinates, and nasal epithelial membrane) contained the highest concentrations of UC. Results indicated that uptake of inhaled methyl bromide could be saturated. Any ( UC)methyl bromide equivalents absorbed, however, would be excreted by concentration-independent mechanisms. 20 references, 5 figures, 4 tables.

  14. Bromide transport in a sandy and a silty soil - a comparative lysimeter study

    NASA Astrophysics Data System (ADS)

    Schober, L.; Iden, S. C.; Durner, W.

    2009-04-01

    The aim of this study was a comparison of bromide leaching through a silty and a sandy soil and the characterization of systematic differences in solute transport in these undisturbed soils of differing texture. The amount of seepage water and bromide concentrations in the water were measured in 5 lysimeters for each soil type for a period of 460 days. Additionally, meteorological data were measured next to the lysimeter station for this period. The water transport regime of the lysimeters was simulated by means of a numerical solution of the Richards equation using the software package HYDRUS 1D. The observed bromide transport was simulated by steady-state approximation, applying the simulation tool CXTFIT, which is implemented in the software package STANMOD, version 2.0. Analysis of the measured data showed that a correct reproduction of the water balance was possible, but required the adaptation of soil-dependent crop coefficients for the potential transpiration of Phacelia and Winter Rape. The mean bromide transport through the sandy soil could be approximately reproduced assuming a bromide uptake by plants. Observed double peaks of some of the individual breakthrough curves, however, indicated that the actual transport regime in the lysimeters was subject to local heterogeneity which cannot be covered by the effective one-dimensional transport model. Bromide transport through the silty soil showed an unexplained mass deficit of nearly 90 % of the applied bromide and the detection of a mean distinct bromide peak in seepage water after percolation of only 0.5 pore volumes. It was not possible to simulate this behaviour with an effective 1D equilibrium or nonequilibrium convection-dispersion model.

  15. Stabilized thallium bromide radiation detectors and methods of making the same

    SciTech Connect

    Leao, Cedric Rocha; Lordi, Vincenzo

    2015-11-24

    According to one embodiment, a crystal includes thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants. According to another embodiment, a system includes a monolithic crystal including thallium bromide (TlBr), one or more positively charged dopants, and one or more negatively charged dopants; and a detector configured to detect a signal response of the crystal.

  16. The effect of pinaverium bromide (LA 1717) on the lower oesophageal sphincter.

    PubMed

    Wöltje, M; Huchzermeyer, H

    1982-01-01

    An acute, double-blind study was carried out in 8 healthy male volunteers to investigate any effect of a new antispasmodic, pinaverium bromide, compared with placebo on the lower oesophageal sphincter. Manometric measurements showed no significant differences in resting pressures either after placebo or a therapeutic dose (200 mg) of pinaverium bromide, suggesting that the active drug does not cause any impairment of function of the lower oesophageal sphincter. PMID:7128186

  17. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Kaji, Masao; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    To improve the thermal performance of high temperature generator of absorption chiller/heater, heat transfer characteristics of flow boiling of lithium bromide aqueous solution in the subcooled region were experimentally investigated. Experiments were made for water and lithium bromide aqueous solution flowing in a rectangular channel (5 mm × 20 mm cross section) with one side wall heated. Boiling onset quality of lithium bromide aqueous solution is greater than that of water. The heat transfer coefficient of lithium bromide aqueous solution is about a half of that of water under the same experimental conditions of inlet velocity and heat flux. The experimental data of heat transfer coefficient for water are compared with the empirical correlation of Thom et al.11) and a fairly good agreement is obtained. The predictive calculations by the method of Sekoguchi et al.12) are compared with the data for water and lithium bromide aqueous solution. Agreement between them is good for water, while the results for lithium bromide aqueous solution are not satisfactory.

  18. Methyl bromide intoxication in four field-workers during removal of soil fumigation sheets.

    PubMed

    Herzstein, J; Cullen, M R

    1990-01-01

    Methyl bromide is a highly toxic and penetrating compound used extensively as an insecticide for dry foodstuffs and as a soil fumigant (in greenhouses and fields) for the control of nematodes, fungi, and weeds. More than 300 cases of systemic poisoning and 60 fatalities attributable to methyl bromide have been reported [Alexeeff and Kilgore, 1983], resulting in substantial regulations concerning its handling, storage, application, and disposal. A recent exposure incident at a Connecticut nursery represents to our knowledge the first report of toxicity stemming from exposures in the field during removal of plastic sheets days after injection of methyl bromide into soil. Following removal of polyethylene sheets covering soil fumigated with methyl bromide, four field-workers developed fatigue and light-headedness and 3 workers noted progressive respiratory, gastrointestinal (GI), and neurologic symptoms. The acute systemic symptoms improved over several days, but later-onset neuropsychiatric symptoms persisted for several weeks. This incident stresses the need for improved worker education and strict adherence to safety precautions during all stages of methyl bromide fumigation and raises the possibility of an increased risk of toxicity associated with methyl bromide fumigation during a cool season. PMID:2305812

  19. Synthesis and biological investigations of 5-substituted pyrimidine nucleosides coupled to a dihydropyridine/pyridinium salt redox chemical delivery system.

    PubMed

    Kumar, R; Wang, L; Wiebe, L I; Knaus, E E

    2001-11-01

    The syntheses, antiviral activities, and partition coefficients (P) of 3'-O-(1-methyl-1,4-dihydropyridyl-3-carbonyl)-coupled nucleosides are described. These novel compounds were designed in an effort to enhance the lipophilicity, and thereby the delivery to the CNS, without compromising the anti-HSV-1 activity of the parental nucleosides. We have previously reported the synthesis of 3'-O-(1-methyl-1,4-dihydropyridyl-3- carbonyl) analogs of 5-iodo-(5), 5-vinyl-(6), and (E)-5-(2-iodovinyl)-2'-deoxyuridines (7). We now report the synthesis of 5-iodo-3'-O-(1-methyl-1,4-dihydropyridyl-3- carbonyl)-5'-O-acetyl-2'-deoxyuridine (15) and 3'-O-(1-methyl-1,4-dihydropyridyl-3-carbonyl)-2'-deoxyuridine (17). Quarternization of the 3'-O-(3-pyridylcarbonyl) compounds (10,12) using iodomethane afforded the corresponding 1-methyl pyridinium salts (13,14) which were reduced with sodium dithionite to yield the corresponding 3'-O-1-methyl-1,4-dihydropyridyl-3-carbonyl compounds (15,16). The deprotection of 3'-O-(1-methyl-1,4-dihydropyridyl- 3-carbonyl)-5'-O-t-butyldimethylsilyl-2'-deoxyuridine (16) with Bu4N+F- afforded 3'-O-(1-methyl-1,4-dihydropyridyl-3-carbonyl)-2'-deoxyuridine (17). Compounds 5-7 and 15 were evaluated for their antiviral activity in vitro against HSV-1, HSV-2, HCMV, and VZV, and were found to retain anti-HSV-1, HSV-2 and VZV activity as compared to their parental nucleosides (1-3). In addition, the cellular toxicity of 3'-O-(1-methyl-1,4-dihydropyridyl-3-carbonyl)-coupled compounds (5-7 and 15) was found to be lower than the parent nucleosides. The lipophilicity of compounds (5-7,15,17) are enhanced substantially, compared to the parent nucleosides, as indicated by an increase in corresponding P values (1-octanol-water) upon replacement of the C-3' hydroxyl by 1-methyl-1,4-dihydropyridyl-3-carbonyl moiety. PMID:11822172

  20. Predicting bromide incorporation in a chlorinated indoor swimming pool.

    PubMed

    Chowdhury, Shakhawat; Mazumder, Abu Jafar; Husain, Tahir

    2016-06-01

    The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9-11.1) and 1.4 (range 0.52-2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5-7.5) and 1.2 (range 0.6-2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0 μg/m(3), respectively, and their ranges were 36.3-105.8 and 44.1-133.6 μg/m(3), respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6 %, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2 %, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools. PMID:26971516

  1. Bacterial oxidation of methyl bromide in fumigated agricultural soils

    USGS Publications Warehouse

    Miller, L.G.; Connell, T.L.; Guidetti, J.R.; Oremland, R.S.

    1997-01-01

    The oxidation of [14C]methyl bromide ([14C]MeBr) to 14CO2 was measured in field experiments with soils collected from two strawberry plots fumigated with mixtures of MeBr and chloropicrin (CCI3NO2). Although these fumigants are considered potent biocides, we found that the highest rates of MeBr oxidation occurred 1 to 2 days after injection when the fields were tarped, rather than before or several days after injection. No oxidation of MeBr occurred in heat-killed soils, indicating that microbes were the causative agents of the oxidation. Degradation of MeBr by chemical and/or biological processes accounted for 20 to 50% of the loss of MeBr during fumigation, with evasion to the atmosphere inferred to comprise the remainder. In laboratory incubations, complete removal of [14C]MeBr occurred within a few days, with 47 to 67% of the added MeBr oxidized to 14CO2 and the remainder of counts associated with the solid phase. Chloropicrin inhibited the oxidation of MeBr, implying that use of this substance constrains the extent of microbial degradation of MeBr during fumigation. Oxidation was by direct bacterial attack of MeBr and not of methanol, a product of the chemical hydrolysis of MeBr. Neither nitrifying nor methane-oxidizing bacteria were sufficiently active in these soils to account for the observed oxidation of MeBr, nor could the microbial degradation of MeBr be linked to cooxidation with exogenously supplied electron donors. However, repeated addition of MeBr to live soils resulted in higher rates of its removal, suggesting that soil bacteria used MeBr as an electron donor for growth. To support this interpretation, we isolated a gram-negative, aerobic bacterium from these soils which grew with MeBr as a sole source of carbon and energy.

  2. Carbon isotope fractionation of methyl bromide during agricultural soil fumigations

    USGS Publications Warehouse

    Bill, M.; Miller, L.G.; Goldstein, Allen H.

    2002-01-01

    The isotopic composition of methyl bromide (CH3Br) has been suggested to be a potentially useful tracer for constraining the global CH3Br budget. In order to determine the carbon isotopic composition of CH3Br emitted from the most significant anthropogenic application (pre-plant fumigation) we directly measured the ??13C of CH3Br released during commercial fumigation. We also measured the isotopic fractionation associated with degradation in agricultural soil under typical field fumigation conditions. The isotopic composition of CH3Br collected in soil several hours after injection of the fumigant was -44.5??? and this value increased to -20.7??? over the following three days. The mean kinetic isotope effect (KIE) associated with degradation of CH3Br in agricultural soil (12???) was smaller than the reported value for methylotrophic bacterial strain IMB-1, isolated from previously fumigated agricultural soil, but was similar to methylotrophic bacterial strain CC495, isolated from a pristine forest litter zone. Using this fractionation associated with the degradation of CH3Br in agricultural soil and the mean ??13C of the industrially manufactured CH3Br (-54.4???), we calculate that the agricultural soil fumigation source has a carbon isotope signature that ranges from -52.8??? to -42.0???. Roughly 65% of industrially manufactured CH3Br is used for field fumigations. The remaining 35% is used for structural and post-harvest fumigations with a minor amount used during industrial chemical manufacturing. Assuming that the structural and post-harvest fumigation sources of CH3Br are emitted without substantial fractionation, we calculate that the ??13C of anthropogenically emitted CH3Br ranges from -53.2??? to -47.5???.

  3. Dicationic Alkylammonium Bromide Gemini Surfactants. Membrane Perturbation and Skin Irritation

    PubMed Central

    Almeida, João A. S.; Faneca, Henrique; Carvalho, Rui A.; Marques, Eduardo F.; Pais, Alberto A. C. C.

    2011-01-01

    Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line), frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of 31P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC) and molecular dynamics (MD) simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by 31P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism. PMID:22102870

  4. Clinical potential of aclidinium bromide in chronic obstructive pulmonary disease

    PubMed Central

    Jones, Paul W

    2015-01-01

    Three long-acting muscarinic antagonists (LAMAs) are now available in Europe, providing clinicians and patients with a choice of interventions, which is important in COPD, which is clinically a heterogeneous disease. The first LAMA, tiotropium, has been widely used over the last decade as a once-daily maintenance therapy in stable COPD to improve patients’ health-related quality of life and to reduce the risk of exacerbations. Administered via the HandiHaler® device, it is safe and well tolerated. Another new once-daily LAMA, glycopyrronium, has also been shown to improve health status and reduce exacerbations, and is well tolerated. The subject of this review is a third LAMA, aclidinium bromide, which was approved as a twice-daily maintenance bronchodilator treatment. In the pivotal Phase III clinical trials, patients receiving aclidinium achieved significantly greater improvements in lung function, reductions in breathlessness, and improvements in health status compared with placebo, for up to 24 weeks. In continuation studies, these improvements were sustained for up to 52 weeks. Pooled data showed exacerbation frequency was significantly reduced with aclidinium versus placebo. Preclinical and pharmacological studies demonstrating low systemic bioavailability and a low propensity to induce cardiac arrhythmias were translated into a favorable tolerability profile in the clinical trial program – the adverse event profile of aclidinium was similar to placebo, with a low incidence of anticholinergic and cardiac adverse events. While additional studies are needed to evaluate its full clinical potential, aclidinium is an important part of this recent expansion of LAMA therapeutic options, providing clinicians and patients with an effective and well-tolerated COPD treatment. PMID:25848244

  5. Tiotropium bromide inhalation powder: a review of its use in the management of chronic obstructive pulmonary disease.

    PubMed

    Keating, Gillian M

    2012-01-22

    The anticholinergic agent tiotropium bromide (Spiriva®) is a long-acting bronchodilator that is indicated for the treatment of chronic obstructive pulmonary disease (COPD). This article reviews the clinical efficacy and tolerability of tiotropium bromide inhalation powder, administered using the HandiHaler® device, in patients with COPD, as well as reviewing its pharmacological properties and the results of pharmacoeconomic analyses. Shorter-term placebo-controlled trials in patients with COPD demonstrated significantly higher trough forced expiratory volume in 1 second (FEV(1)) responses with tiotropium bromide than with placebo, confirming it has a duration of action of ≥24 hours and is suitable for once-daily administration. Lung function improved to a greater extent with tiotropium bromide than with ipratropium bromide or, in most instances, salmeterol. Indacaterol was shown to be noninferior to tiotropium bromide in terms of the trough FEV(1) response. The large, 4-year UPLIFT® trial did not show a significant reduction in the annual rate of decline in FEV(1) with tiotropium bromide versus placebo in patients with COPD, although subgroup analyses demonstrated a significantly lower rate of decline with tiotropium bromide than with placebo in some patient groups (e.g. patients with moderate COPD, patients aged ≥50 years, patients not receiving maintenance therapy at baseline). Tiotropium bromide prevented exacerbations in patients with COPD, with a significantly lower exacerbation rate and a significantly longer time to first exacerbation seen with tiotropium bromide than with placebo or salmeterol. Exacerbation rates did not significantly differ between patients receiving tiotropium bromide and those receiving salmeterol/fluticasone propionate. Tiotropium bromide also had beneficial effects on health-related quality of life (HR-QOL) and other endpoints, such as dyspnoea and rescue medication use. Combination therapy with tiotropium bromide plus

  6. Glutathione transferase activity and formation of macromolecular adducts in two cases of acute methyl bromide poisoning.

    PubMed Central

    Garnier, R; Rambourg-Schepens, M O; Müller, A; Hallier, E

    1996-01-01

    OBJECTIVES: To determine the activity of glutathione transferase and to measure the S-methylcysteine adducts in blood proteins, after acute inhalation exposure to methyl bromide. To examine the influence of the polymorphism of glutathione-S-transferase theta (GSTT1) on the neurotoxicity of methyl bromide. METHODS: Two workers acutely exposed to methyl bromide with inadequate respiratory protective devices were poisoned. Seven weeks after the accident, blood samples were drawn from both patients, for measurement of glutathione transferase activity in erythrocytes (conjugator status--that is, GSTT1 phenotype) and measurement of binding products of methyl bromide with blood proteins. Conjugator status was determined by a standard procedure. The binding product of methyl bromide, S-methylcysteine, was measured in globin and albumin. RESULTS: Duration and intensity of exposure were identical for both patients as they worked together with the same protective devices and with similar physical effort. However, one patient had very severe poisoning, whereas the other only developed mild neurotoxic symptoms. The first patient was a "conjugator" with normal glutathone transferase activity, whereas this activity was undetectable in the erythrocytes of the second patient, who consequently had higher concentrations of S-methylcysteine adduct in albumin (149 v 91 nmol/g protein) and in globin (77 v 30 nmol/g protein). CONCLUSIONS: Methyl bromide is genotoxic and neurotoxic. Its genotoxicity seems to be the consequence of the alkylating activity of the parent compound, and conjugation to glutathione has a protective effect. The data presented here suggest a different mechanism for methyl bromide neurotoxicity which could be related to the transformation of methylglutathione into toxic metabolites such as methanethiol and formaldehyde. If such metabolites are the ultimate toxic species, N-acetylcysteine treatment could have a toxifying rather than a detoxifying effect. PMID:8704864

  7. Aclidinium bromide combined with formoterol inhibits remodeling parameters in lung epithelial cells through cAMP.

    PubMed

    Lambers, Christopher; Costa, Luigi; Ying, Qi; Zhong, Jun; Lardinois, Didier; Dekan, Gerhard; Schuller, Elisabeth; Roth, Michael

    2015-12-01

    Combined muscarinic receptor antagonists and long acting β2-agonists improve symptom control in chronic obstructive pulmonary disease (COPD) significantly. In clinical studies aclidinium bromide achieved better beneficial effects than other bronchodilators; however, the underlying molecular mechanisms are unknown. This study assessed the effect of aclidinium bromide combined with formoterol on COPD lung (n=20) and non-COPD lung (n=10) derived epithelial cells stimulated with TGF-β1+carbachol on: (i) the generation of mesenchymal cells in relation to epithelial cells, (II) extracellular matrix (ECM) deposition, and (iii) the interaction of ECM on the generation of epithelial and mesenchymal cells. TGF-β1+carbachol enhanced the generation of mesenchymal cells, which was significantly reduced by aclidinium bromide or formoterol. The effect of combined drugs was additive. Inhibition of p38 MAP kinase and Smad by specific inhibitors or aclidinium bromide reduced the generation of mesenchymal cells. In mesenchymal cells, TGF-β1+carbachol induced the deposition of collagen-I and fibronectin which was prevented by both drugs dose-dependently. Formoterol alone reduced collagen-I deposition via cAMP, this however, was overruled by TGF-β1+carbachol and rescued by aclidinium bromide. Inhibition of fibronectin was cAMP independent, but involved p38 MAP kinase and Smad. Seeding epithelial cells on ECM collagen-I and fibronectin induced mesenchymal cell generation, which was reduced by aclidinium bromide and formoterol. Our results suggest that the beneficial effect of aclidinium bromide and formoterol involves cAMP affecting both, the accumulation of mesenchymal cells and ECM remodeling, which may explain the beneficial effect of the drugs on lung function in COPD. PMID:26546746

  8. Bromine and bromide content in soils: Analytical approach from total reflection X-ray fluorescence spectrometry.

    PubMed

    Gallardo, Helena; Queralt, Ignasi; Tapias, Josefina; Candela, Lucila; Margui, Eva

    2016-08-01

    Monitoring total bromine and bromide concentrations in soils is significant in many environmental studies. Thus fast analytical methodologies that entail simple sample preparation and low-cost analyses are desired. In the present work, the possibilities and drawbacks of low-power total reflection X-ray fluorescence spectrometry (TXRF) for the determination of total bromine and bromide contents in soils were evaluated. The direct analysis of a solid suspension using 20 mg of fine ground soil (<63 μm) gave a 3.7 mg kg(-1) limit of detection for bromine which, in most cases, was suitable for monitoring total bromine content in soils (Br content range in soils = 5-40 mg kg(-1)). Information about bromide determination in soils is also possible by analyzing the Br content in water soil extracts. In this case, the TXRF analysis can be directly performed by depositing 10 μL of the internal standardized soil extract sample on a quartz glass reflector in a measuring time of 1500 s. The bromide limit of detection by this approach was 10 μg L(-1). Good agreement was obtained between the TXRF results for the total bromine and bromide determinations in soils and those obtained by other popular analytical techniques, e.g. energy dispersive X-ray fluorescence spectrometry (total bromine) and ionic chromatography (bromide). As a study case, the TXRF method was applied to study bromine accumulation in two agricultural soils fumigated with a methyl bromide pesticide and irrigated with regenerated waste water. PMID:27179429

  9. Residential Proximity to Methyl Bromide Use and Birth Outcomes in an Agricultural Population in California

    PubMed Central

    Gemmill, Alison; Gunier, Robert B.; Bradman, Asa; Eskenazi, Brenda

    2013-01-01

    Background: Methyl bromide, a fungicide often used in strawberry cultivation, is of concern for residents who live near agricultural applications because of its toxicity and potential for drift. Little is known about the effects of methyl bromide exposure during pregnancy. Objective: We investigated the relationship between residential proximity to methyl bromide use and birth outcomes. Methods: Participants were from the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study (n = 442), a longitudinal cohort study examining the health effects of environmental exposures on pregnant women and their children in an agricultural community in northern California. Using data from the California Pesticide Use Reporting system, we employed a geographic information system to estimate the amount of methyl bromide applied within 5 km of a woman’s residence during pregnancy. Multiple linear regression models were used to estimate associations between trimester-specific proximity to use and birth weight, length, head circumference, and gestational age. Results: High methyl bromide use (vs. no use) within 5 km of the home during the second trimester was negatively associated with birth weight (β = –113.1 g; CI: –218.1, –8.1), birth length (β = –0.85 cm; CI: –1.44, –0.27), and head circumference (β = –0.33 cm; CI: –0.67, 0.01). These outcomes were also associated with moderate methyl bromide use during the second trimester. Negative associations with fetal growth parameters were stronger when larger (5 km and 8 km) versus smaller (1 km and 3 km) buffer zones were used to estimate exposure. Conclusions: Residential proximity to methyl bromide use during the second trimester was associated with markers of restricted fetal growth in our study. PMID:23603811

  10. Bacterial Oxidation of Methyl Bromide in Fumigated Agricultural Soils

    PubMed Central

    Miller, L. G.; Connell, T. L.; Guidetti, J. R.; Oremland, R. S.

    1997-01-01

    The oxidation of [(sup14)C]methyl bromide ([(sup14)C]MeBr) to (sup14)CO(inf2) was measured in field experiments with soils collected from two strawberry plots fumigated with mixtures of MeBr and chloropicrin (CCl(inf3)NO(inf2)). Although these fumigants are considered potent biocides, we found that the highest rates of MeBr oxidation occurred 1 to 2 days after injection when the fields were tarped, rather than before or several days after injection. No oxidation of MeBr occurred in heat-killed soils, indicating that microbes were the causative agents of the oxidation. Degradation of MeBr by chemical and/or biological processes accounted for 20 to 50% of the loss of MeBr during fumigation, with evasion to the atmosphere inferred to comprise the remainder. In laboratory incubations, complete removal of [(sup14)C]MeBr occurred within a few days, with 47 to 67% of the added MeBr oxidized to (sup14)CO(inf2) and the remainder of counts associated with the solid phase. Chloropicrin inhibited the oxidation of MeBr, implying that use of this substance constrains the extent of microbial degradation of MeBr during fumigation. Oxidation was by direct bacterial attack of MeBr and not of methanol, a product of the chemical hydrolysis of MeBr. Neither nitrifying nor methane-oxidizing bacteria were sufficiently active in these soils to account for the observed oxidation of MeBr, nor could the microbial degradation of MeBr be linked to cooxidation with exogenously supplied electron donors. However, repeated addition of MeBr to live soils resulted in higher rates of its removal, suggesting that soil bacteria used MeBr as an electron donor for growth. To support this interpretation, we isolated a gram-negative, aerobic bacterium from these soils which grew with MeBr as a sole source of carbon and energy. PMID:16535728

  11. Chlorine-36, bromide, and the origin of spring water

    USGS Publications Warehouse

    Davis, S.N.; Cecil, L.D.; Zreda, M.; Moysey, S.

    2001-01-01

    Natural ratios of chlorine-36 (36Cl) to stable chlorine (i.e., 36Cl/Cl ?? 10-15) vary in shallow groundwater of the United States from about 50 in coastal areas to about 1400 in the northern Rocky Mountains. Ratios lower than these indicate the presence of chloride (Cl-) that has been isolated from the atmosphere for hundreds of thousands of years, if not longer. Higher ratios, which can exceed 5000, usually originate from fallout from testing thermonuclear devices in the western Pacific in the 1950s. Natural mass ratios of chloride to bromide (Cl-/Br-) in precipitation vary in the United States from about 250 in coastal areas to about 50 in the north-central states. Lower ratios may suggest contamination from human sources. Higher ratios, which may exceed 2000, commonly reflect the dissolution of halite. Seawater has a Cl-/Br- ratio of 290. Both 36Cl and Cl-/Br- ratios have been measured in 21 samples of spring water collected from springs in 10 different states. Brackish water from Saratoga Springs area in New York has low values for both 36Cl and Cl-/Br- ratios. This indicates that a large component of the water has a very deep origin. Brackish water from Alexander Springs in Florida has a low 36Cl ratio but a high Cl-/Br- ratio similar to seawater. This suggests the addition of ancient seawater that may be trapped in the aquifer. Big Spring in Iowa discharges water with a very high Cl-/Br- ratio but a moderate 36Cl ratio. The high ratio of Cl-/Br- may be produced by dissolution of road salt or agricultural chemicals. Of the 21 springs sampled, only 10 appeared to have potable water not significantly affected by human activity. Chlorine-36 from testing of nuclear devices is still being flushed out of four of the spring systems that were sampled. Thus, more than 45 years have passed since 36Cl was introduced into the aquifers feeding the springs and the systems, as yet, have not been purged. Published by Elsevier Science B.V.

  12. Bacterial oxidation of methyl bromide in fumigated agricultural soils.

    PubMed

    Miller, L G; Connell, T L; Guidetti, J R; Oremland, R S

    1997-11-01

    The oxidation of [(sup14)C]methyl bromide ([(sup14)C]MeBr) to (sup14)CO(inf2) was measured in field experiments with soils collected from two strawberry plots fumigated with mixtures of MeBr and chloropicrin (CCl(inf3)NO(inf2)). Although these fumigants are considered potent biocides, we found that the highest rates of MeBr oxidation occurred 1 to 2 days after injection when the fields were tarped, rather than before or several days after injection. No oxidation of MeBr occurred in heat-killed soils, indicating that microbes were the causative agents of the oxidation. Degradation of MeBr by chemical and/or biological processes accounted for 20 to 50% of the loss of MeBr during fumigation, with evasion to the atmosphere inferred to comprise the remainder. In laboratory incubations, complete removal of [(sup14)C]MeBr occurred within a few days, with 47 to 67% of the added MeBr oxidized to (sup14)CO(inf2) and the remainder of counts associated with the solid phase. Chloropicrin inhibited the oxidation of MeBr, implying that use of this substance constrains the extent of microbial degradation of MeBr during fumigation. Oxidation was by direct bacterial attack of MeBr and not of methanol, a product of the chemical hydrolysis of MeBr. Neither nitrifying nor methane-oxidizing bacteria were sufficiently active in these soils to account for the observed oxidation of MeBr, nor could the microbial degradation of MeBr be linked to cooxidation with exogenously supplied electron donors. However, repeated addition of MeBr to live soils resulted in higher rates of its removal, suggesting that soil bacteria used MeBr as an electron donor for growth. To support this interpretation, we isolated a gram-negative, aerobic bacterium from these soils which grew with MeBr as a sole source of carbon and energy. PMID:16535728

  13. The ocean in near equilibrium with atmospheric methyl bromide

    NASA Astrophysics Data System (ADS)

    Hu, Lei; Yvon-Lewis, Shari; Liu, Yina; Bianchi, Thomas S.

    2012-09-01

    Saturation-anomaly measurements of methyl bromide (CH3Br) were made in the eastern Pacific (3/30-4/27, 2010) and the eastern Atlantic (10/25-11/26, 2010) to assess the oceanic saturation state as the phaseout of fumigation - non-Quarantine and Pre-Shipment (non-QPS) uses of CH3Br nears completion and atmospheric concentrations continue to decline. These cruises occurred 16 years after the Bromine Latitudinal Air-Sea Transect (BLAST) cruises, which were conducted in the same regions and first established a global oceanic net sink of -12.6 Gg yr-1 for atmospheric CH3Br in 1994. Results from this study suggest saturation anomalies of CH3Br in the surface ocean have become less negative than those observed 16 years ago as the atmospheric burden has declined over the past decade. The global net sea-to-air flux was estimated at 0 to 3 Gg yr-1 in 2010, suggesting that the ocean may become a net small source to atmospheric CH3Br. There are no significant differences between this study and previous studies for measured biological loss rate constants and calculated annual production rates, suggesting that annual production rates and biological degradation rate constants for CH3Br in the surface ocean have likely remained relatively constant over the past 16 years. When including the biological loss rate constants from this study and all previous studies, the mean global biological loss rate constant is constrained to 0.05 ± 0.01 d-1 (at a 95% confidence level). Combining chemical and eddy degradation rate constants, and using an updated gas transfer velocity, we estimate the CH3Br partial atmospheric lifetime with respect to oceanic loss to be 3.1 (2.3 to 5.0) years. Although the new partial atmospheric lifetime is about 1.3 years longer than the best prior estimate, it does not change the overall atmospheric lifetime of CH3Br, 0.8 (0.7-0.9) years.

  14. Formation of NDMA and halogenated DBPs by chloramination of tertiary amines: the influence of bromide ion.

    PubMed

    Le Roux, Julien; Gallard, Hervé; Croué, Jean-Philippe

    2012-02-01

    The formation of NDMA and other DBPs (including THMs, HANs, and HKs) has been investigated by chloramination of several tertiary amines in the absence and presence of bromide ion. NDMA formation from the most reactive tertiary amines (e.g., dimethylaminomethylfurfuryl alcohol or DMP30) was enhanced in the presence of bromide due to the formation of brominated oxidant species such as bromochloramine (NHBrCl) and the hypothetical UDMH-Br as an intermediate. The formation of NDMA by chloramination of less reactive model compounds was inhibited in the presence of bromide. This can be explained by competitive reactions leading to the production of brominated DBPs (i.e., THMs). In the presence of bromide, the formation of brominated THMs during chloramination can be attributed to the presence of small amounts of HOBr produced by the decomposition of chloramines and bromamines. The results are of particular interest to understand NDMA formation mechanisms, especially during chloramination of wastewaters impacted by anthropogenic tertiary amines and containing bromide ion. PMID:22214364

  15. Determination of methyl bromide in air samples by headspace gas chromatography

    SciTech Connect

    Woodrow, J.E.; McChesney, M.M.; Seiber, J.N.

    1988-03-01

    Methyl bromide is extensively used in agriculture (4 x 10/sup 6/ kg for 1985 in California alone as a fumigant to control nematodes, weeds, and fungi in soil and insect pests in harvested grains and nuts. Given its low boiling point (3.8/sup 0/C) and high vapor pressure (approx. 1400 Torr at 20/sup 0/C), methyl bromide will readily diffuse if not rigorously contained. Methods for determining methyl bromide and other halocarbons in air vary widely. A common practice is to trap the material from air on an adsorbent, such as polymeric resins, followed by thermal desorption either directly into the analytical instrumentation or after intermediary cryofocusing. While in some cases analytical detection limits were reasonable (parts per million range), many of the published methods were labor intensive and required special handling techniques that precluded high sample throughput. They describe here a method for the sampling and analysis of airborne methyl bromide that was designed to handle large numbers of samples through automating some critical steps of the analysis. The result was a method that allowed around-the-clock operation with a minimum of operator attention. Furthermore, the method was not specific to methyl bromide and could be used to determine other halocarbons in air.

  16. [Bowel obstruction-induced cholinergic crisis with progressive respiratory failure following distigmine bromide treatment].

    PubMed

    Kobayashi, Kazuki; Sekiguchi, Hiroshi; Sato, Nobuhiro; Hirose, Yasuo

    2016-03-01

    A 54-year-old female experienced rapid respiratory failure while being transported in an ambulance to our emergency department for evaluation and management of constipation and abdominal pain. The patient was on treatment with distigmine bromide for postoperative urination disorder and magnesium oxide for constipation. Increased salivary secretions, diminished respiratory excursion, type 2 respiratory failure (PaCO2 : 65 mmHg), low serum cholinesterase, and hypermagnesemia were detected. Imaging studies revealed that the patient had bilateral aspiration pneumonia, fecal impaction in the rectum, and a distended colon causing ileus. The patient was mechanically ventilated and was weaned off the ventilator on day 3. Therapeutic drug monitoring after discharge revealed that the serum level of distigmine bromide on admission was markedly elevated (377.8 ng/mL vs. the normal therapeutic level of 5-10 ng/mL). Distigmine bromide induced a cholinergic crisis with a resultant increase in airway secretions and respiratory failure. In this particular case, orally administered distigmine bromide was excessively absorbed because of prolonged intestinal transit time secondary to fecal impaction and sluggish bowel movement; this caused a cholinergic crisis and hypermagnesemia contributing to respiratory failure. Clinicians should be aware that bowel obstruction in a patient treated with distigmine bromide can increase the risk of a cholinergic crisis. PMID:27255021

  17. Mepenzolate bromide promotes diabetic wound healing by modulating inflammation and oxidative stress

    PubMed Central

    Zheng, Yongjun; Wang, Xingtong; Ji, Shizhao; Tian, Song; Wu, Haibin; Luo, Pengfei; Fang, He; Wang, Li; Wu, Guosheng; Xiao, Shichu; Xia, Zhaofan

    2016-01-01

    Diabetic wounds are characterized by persistent inflammation and the excessive production of reactive oxygen species, thus resulting in impaired wound healing. Mepenzolate bromide, which was originally used to treat gastrointestinal disorders in clinical settings, has recently been shown to display beneficial effects in chronic obstructive pulmonary disease and pulmonary fibrosis of a mouse model by inhibiting inflammatory responses and reducing oxidative stress. However,the role of mepenzolate bromide in diabetic wound healing is still unclear. In this study, full-thickness excisional skin wounds were created on the backs of db/db mice, and mepenzolate bromide was topically applied to the wound bed. We found that mepenzolate bromide significantly promoted diabetic wound healing by measuring wound closure rate and histomorphometric analyses. Further studies showed that inflammation was inhibited by assessing the number of macrophages and levels of pro-inflammatory cytokines and pro-healing cytokines in the wounds. Furthermore, oxidative stress was reduced by monitoring the levels of MDA and H2O2 and the activities of glutathione peroxidase and catalase in the wounds. These results demonstrated the potential application of mepenzolate bromide for treating diabetic ulcers and other chronic wounds in clinics. PMID:27398156

  18. The second harmonic generation and the photoelectric property studies on a new dye, (E)- N-octadecyl-4-[2-(4-dimethylaminophenyl) enamine] pyridinium iodide

    NASA Astrophysics Data System (ADS)

    Zhai, Jin; Huang, Chun-Hui; Wei, Tian-Xin; Yu, An-Chi; Zhao, Xin-Sheng

    1999-03-01

    According to quantum chemistry calculation, a Schiff-base (E)- N-octadecyl-4-[2-(4-dimethylaminophenyl) enamine] pyridinium iodide with a large dipole moment difference between the excited state and the ground state (Δ μ), is designed and synthesized as a second-order non-linear optical material. Its second-order susceptibility ( χ(2)zzz) is evaluated to be 279.4 pm V -1, which is larger than that of the hemicyanine which is known as one of the best dyes in the second harmonic generation (SHG) behavior. Its LB film formation properties were studied. The photoelectric conversion property is not as good as expected. According to the experiments and the results of the quantum chemistry calculation, an explanation of this phenomenon is proposed.

  19. Aging Effects on the Properties of Imidazolium-, Quaternary Ammonium-, Pyridinium-, and Pyrrolidinium-Based Ionic Liquids Used in Fuel and Energy Production

    SciTech Connect

    Fox, Elise B.; Smith, L. Taylor; Williamson, Tyler K.; Kendrick, Sarah E.

    2013-11-21

    Ionic liquids (ILs) are often cited for their excellent thermal stability, a key property for their use as solvents and in the chemical processing of biofuels. However, there has been little supporting data on the long-term aging effect of the temperature on these materials. Imizadolium-, quaternary ammonium-, pyridinium-, and pyrrolidnium-based ILs with the bis(trifluoromethylsulfonyl)imide and bis(perfluoroethylsulfonyl)imide anions were aged for 2520 h (15 weeks) at 200 °C in air to determine the effects of an oxidizing environment on their chemical structure and thermal stability over time. Finally, it was found that the minor changes in the cation chemistry could greatly affect the properties of the ILs over time.

  20. (E)-4-{2-[(2-Hy­droxy­naphthalen-1-yl)methyl­idene]hydrazinecarbon­yl}pyridinium nitrate

    PubMed Central

    Bikas, Rahman; Hosseini Monfared, Hassan; Lis, Tadeusz; Siczek, Milosz

    2012-01-01

    The title compound, C17H14N3O2 +·NO3 −, is an aroylhydrazone-based material consisting of a 4-(hydrazinecarbon­yl)pyridinium cation and a nitrate anion. In the cation, the dihedral angle between the benzene ring and the naphthalene ring system is 2.20 (7)°. In the cation, the configuration about the C=N bond is E. There is an intra­molecular O—H⋯N hydrogen bond in the cation, and the supra­molecular structure is stabilized by inter­molecular N—H⋯O hydrogen bonds and weak C—H⋯O contacts between the cation and the nitrate anion. PMID:22346992

  1. Bis[4-(dimethyl-amino)pyridinium] tetra-bromidobis(4-chloro-phen-yl)stannate(IV)-4-bromo-chloro-benzene (1/1).

    PubMed

    Lee, See Mun; Lo, Kong Mun; Mohd Ali, Hapipah; Robinson, Ward T

    2009-01-01

    In the title compound, (C(7)H(11)N(2))(2)[SnBr(4)(C(6)H(4)Cl)(2)]·C(6)H(4)BrCl, the Sn(IV) atom in the tetra-bromidobis(4-chloro-phen-yl)stannate(IV) anion lies on a centre of inversion. The distances between the 4-(dimethyl-amino)pyridinium N atom and the Br atoms of the anion are 3.450 (2) and 3.452 (2) Å, suggesting weak hydrogen bonding. The 4-bromo-chloro-benzene solvent mol-ecule, which is a bromination by-product from the reaction, is disordered about a twofold rotation axis with approximately equal occupancy. PMID:21577402

  2. Simultaneous free and glycosylated pyridinium crosslink determination in urine: validation of an HPLC-fluorescence method using a deoxypyridinoline homologue as internal standard.

    PubMed

    Monticelli, Elena; Aman, Caroline Stéphanie; Costa, Maria Letizia; Rota, Paola; Bogdan, Daniela; Allevi, Pietro; Cighetti, Giuliana

    2011-09-15

    Pyridinoline (Pyr), deoxypyridinoline (D-Pyr), galactosyl-pyridinoline (Gal-Pyr) and glucosyl-galactosyl pyridinoline (GluGal-Pyr) are enzymatic mature pyridinium crosslinks. Generally, only total Pyr and D-Pyr urinary amounts (free+bound forms) are evaluated by HPLC as indices of bone resorption. This report describes the validation of an HPLC-fluorescence method for the simultaneous evaluation of free Pyr and D-Pyr, together with GluGal-Pyr and Gal-Pyr, in urine of healthy women (n=20, aged 27-41) and girls (n=20, aged 5-10). The use of an unnatural D-Pyr homologue, here proposed for the first time as internal standard, and of pure Pyr, D-Pyr, GluGal-Pyr and Gal-Pyr synthesized to be used as primary calibrators, guarantees method specificity and correct crosslink quantification. Urine, spiked with IS, was solid-phase extracted prior to HPLC analysis. Total Pyr and D-Pyr amounts were also evaluated after urine hydrolysis. The HPLC method was validated for selectivity, sensitivity, linearity, precision, accuracy, recovery and stability for all measured crosslinks. Both free and total Pyr and D-Pyr as well as GluGal-Pyr and Gal-Pyr amounts were significantly higher in girls than in women (p<0.0001), indicating an increased collagen turnover rather than only bone turnover. Gal-Pyr, for the first time evaluated in girls, was under its lower quantification limit (pyridinium crosslinks might provide more information on the degradation of various types of collagen than only that of total Pyr and D-Pyr. Moreover, this validated method could be a useful non-invasive technique for studying pathological conditions characterized by modified glycosylation enzyme activity and for more clinical investigation on bone fragility. PMID:21855424

  3. Current and Potential Future Bromide Loads from Coal-Fired Power Plants in the Allegheny River Basin and Their Effects on Downstream Concentrations.

    PubMed

    Good, Kelly D; VanBriesen, Jeanne M

    2016-09-01

    The presence of bromide in rivers does not affect ecosystems or present a human health risk; however, elevated concentrations of bromide in drinking water sources can lead to difficulty meeting drinking water disinfection byproduct (DBP) regulations. Recent attention has focused on oil and gas wastewater and coal-fired power plant wet flue gas desulfurization (FGD) wastewater bromide discharges. Bromide can be added to coal to enhance mercury removal, and increased use of bromide at some power plants is expected. Evaluation of potential increases in bromide concentrations from bromide addition for mercury control is lacking. The present work utilizes bromide monitoring data in the Allegheny River and a mass-balance approach to elucidate bromide contributions from anthropogenic and natural sources under current and future scenarios. For the Allegheny River, the current bromide is associated approximately 49% with oil- and gas-produced water discharges and 33% with coal-fired power plants operating wet FGD, with 18% derived from natural sources during mean flow conditions in August. Median wet FGD bromide loads could increase 3-fold from 610 to 1900 kg/day if all plants implement bromide addition for mercury control. Median bromide concentrations in the lower Allegheny River in August would rise to 410, 200, and 180 μg/L under low-, mean-, and high-flow conditions, respectively, for the bromide-addition scenario. PMID:27538590

  4. Methyl bromide: ocean sources, ocean sinks, and climate sensitivity.

    PubMed

    Anbar, A D; Yung, Y L; Chavez, F P

    1996-03-01

    The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The quantity of CH3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmosphere is poorly constrained; measurements in seawater and the atmosphere have been used to justify both a large oceanic CH3Br flux to the atmosphere and a small net ocean sink. Since the consumption reactions are extremely temperature-sensitive, small temperature variations have large effects on the CH3Br concentration in seawater, and therefore on the exchange between the atmosphere and the ocean. The net CH3Br flux is also sensitive to variations in the rate of CH3Br production. We have quantified these effects using a simple steady state mass balance model. When CH3Br production rates are linearly scaled with seawater chlorophyll content, this model reproduces the latitudinal variations in marine CH3Br concentrations observed in the east Pacific Ocean by Singh et al. [1983] and by Lobert et al. [1995]. The apparent correlation of CH3Br production with primary production explains the discrepancies between the two observational studies, strengthening recent suggestions that the open ocean is a small net sink for atmospheric CH3Br, rather than a large net source. The Southern Ocean is implicated as a possible large net source of CH3Br to the atmosphere. Since our model indicates that both the direction and magnitude of CH3Br exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity, and since the rate of CH3Br production in the oceans is comparable to the rate at which this compound is introduced to the atmosphere, even small

  5. Methyl bromide: ocean sources, ocean sinks, and climate sensitivity

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Yung, Y. L.; Chavez, F. P.

    1996-01-01

    The oceans play an important role in the geochemical cycle of methyl bromide (CH3Br), the major carrier of O3-destroying bromine to the stratosphere. The quantity of CH3Br produced annually in seawater is comparable to the amount entering the atmosphere each year from natural and anthropogenic sources. The production mechanism is unknown but may be biological. Most of this CH3Br is consumed in situ by hydrolysis or reaction with chloride. The size of the fraction which escapes to the atmosphere is poorly constrained; measurements in seawater and the atmosphere have been used to justify both a large oceanic CH3Br flux to the atmosphere and a small net ocean sink. Since the consumption reactions are extremely temperature-sensitive, small temperature variations have large effects on the CH3Br concentration in seawater, and therefore on the exchange between the atmosphere and the ocean. The net CH3Br flux is also sensitive to variations in the rate of CH3Br production. We have quantified these effects using a simple steady state mass balance model. When CH3Br production rates are linearly scaled with seawater chlorophyll content, this model reproduces the latitudinal variations in marine CH3Br concentrations observed in the east Pacific Ocean by Singh et al. [1983] and by Lobert et al. [1995]. The apparent correlation of CH3Br production with primary production explains the discrepancies between the two observational studies, strengthening recent suggestions that the open ocean is a small net sink for atmospheric CH3Br, rather than a large net source. The Southern Ocean is implicated as a possible large net source of CH3Br to the atmosphere. Since our model indicates that both the direction and magnitude of CH3Br exchange between the atmosphere and ocean are extremely sensitive to temperature and marine productivity, and since the rate of CH3Br production in the oceans is comparable to the rate at which this compound is introduced to the atmosphere, even small

  6. Seeded Growth of Monodisperse Gold Nanorods Using Bromide-Free Surfactant Mixtures

    SciTech Connect

    Ye, XC; Gao, YZ; Chen, J; Reifsnyder, DC; Zheng, C; Murray, CB

    2013-05-01

    We demonstrate for the first time that monodisperse gold nanorods (NRs) with broadly tunable dimensions and longitudinal surface plasmon resonances can be synthesized using a bromide-free surfactant mixture composed of alkyltrimethylammonium chloride and sodium oleate. It is found that uniform gold NRs can be obtained even with an iodide concentration approaching 100 mu M in the growth solution. In contrast to conventional wisdom, our results provide conclusive evidence that neither bromide as the surfactant counterion nor a high concentration of bromide ions in the growth solution is essential for gold NR formation. Correlated electron microscopy study of three-dimensional structures of gold NRs reveals a previously unprecedented octagonal prismatic structure enclosed predominantly by high index {310} crystal planes. These findings should have profound implications for a comprehensive mechanistic understanding of seeded growth of anisotropic metal nanocrystals.

  7. A comparison between the gastric and salivary concentration of iodide, pertechnetate, and bromide in man

    PubMed Central

    Harden, R. McG.; Alexander, W. D.; Shimmins, J.; Chisholm, D.

    1969-01-01

    The concentration of iodide (I−) and pertechnetate (TcO4−) and bromide (Br−) has been measured simultaneously in gastric juice and parotid saliva. The combined gastric and salivary clearance for iodide and pertechnetate is more than twice the clearance of these ions by the thyroid gland. The concentration of the ions was in the order I−>TcO4−>Br− in both gastric juice and saliva. Differences exist between the secretion of iodide, pertechnetate, and bromide. Bromide, in contrast to iodide and pertechnetate, was found to be more concentrated in gastric juice than in saliva. The ratio of the iodide to pertechnetate clearance was greater in gastric juice than in saliva. PMID:5358585

  8. Salty glycerol versus salty water surface organization: bromide and iodide surface propensities.

    PubMed

    Huang, Zishuai; Hua, Wei; Verreault, Dominique; Allen, Heather C

    2013-07-25

    Salty NaBr and NaI glycerol solution interfaces are examined in the OH stretching region using broadband vibrational sum frequency generation (VSFG) spectroscopy. Raman and infrared (IR) spectroscopy are used to further understand the VSFG spectroscopic signature. The VSFG spectra of salty glycerol solutions reveal that bromide and iodide anions perturb the interfacial glycerol organization in a manner similar as that found in aqueous halide salt solutions, thus confirming the presence of bromide and iodide anions at the glycerol surface. Surface tension measurements are consistent with the surface propensity suggested by the VSFG data and also show that the surface excess increases with increasing salt concentration, similar to that of water. In addition, iodide is shown to have more surface prevalence than bromide, as has also been determined from aqueous solutions. These results suggest that glycerol behaves similarly to water with respect to surface activity and solvation of halide anions at its air/liquid interface. PMID:23663033

  9. Bromide and iodide removal from waters under dynamic conditions by Ag-doped aerogels.

    PubMed

    Sánchez-Polo, M; Rivera-Utrilla, J; von Gunten, U

    2007-02-01

    The objective of this study was to analyze the efficiency of Ag-doped aerogels in the removal of bromide and iodide from water. To test the applicability of these aerogels in water treatment, adsorption of bromide and iodide was studied under dynamic conditions using waters from Lake Zurich and a mineral water. The results obtained by using these waters showed a high breakthrough volume (V(0.02)=0.4 L) of the columns, while the height of the mass transfer zone (H(MTZ)=6.8 cm) was low, regardless of the anion under study. Bromide- and iodide-saturated columns were regenerated with NH4OH. No change in the column characteristics was observed after two regeneration treatments, regardless of the type of water considered. PMID:17109877

  10. Calculated interactions of a nitro group with aromatic rings of crystalline picryl bromide

    PubMed Central

    Huang, Lulu; Massa, Lou; Karle, Jerome

    2008-01-01

    Several crystalline polymorphs have been discovered for picryl bromide. Among the several forces that control the formation of such polymorphs are the interactions among the nitro groups and phenyl rings of those crystals. Although there are >300 structures to be found in the Cambridge Structural Database displaying the nitro-phenyl interaction, nonetheless this interesting, and apparently important, interaction, seems not to have been discussed within any of the papers reporting the structures. In this article, quantum calculations are reported that assess the strength of these nitro-phenyl interactions within a crystal of picryl bromide. The rather flat molecules of picryl bromide are arranged in layered planes within the crystal, and we examine the attractive interactions that occur within a given plane, and between adjacent planes. Calculations of Hartree Fock and Møller Plesset perturbation theory carried to a second-order expansion are used. Both quantum mechanical approximations are implemented with 6–31G* basis functions. PMID:18780785

  11. Dispersion characteristics and sinks for methyl bromide vapors downwind of treated agricultural fields

    SciTech Connect

    Seiber, J.N.; Woodrow, J.E.; Dowling, K.

    1995-12-31

    A study of methyl bromide volatilization and fate from a treated agricultural field was conducted in Monterey County, California, in 1994. Air concentrations were measured above and downwind from the field with the objective of comparing vertical and horizontal flux terms. Another objective was to compare observed downwind concentrations with those predicted by the Industrial Source Complex model, to begin the process of identifying potential sinks which might scavenge methyl bromide from the atmosphere. The final objective was to determine the limit of detection of our analytical method for airborne methyl bromide using field samples representing a wide range of concentrations. A description of the methods and results of the study will be presented, along with a discussion of data quality and interpretation.

  12. Inhibitory effect of pinaverium bromide on gastrointestinal contractile activity in conscious dogs.

    PubMed

    Itoh, Z; Takahashi, I

    1981-01-01

    The inhibitory effect of 4-(6-bromoveratryl)-4-(2-[2-(6,6-dimethyl-2-norpinyl)-ethoxy]-ethyl)-morpholinium hydroxide (pinaverium bromide), a quaternary ammonium derivative, on the contractile activity of the gastrointestinal tract from the stomach to the colon was investigated in six conscious dogs. Gastrointestinal motor activity was monitored by means of chronically implanted force transducers. Pinaverium bromide was continuously administered i.v. for 30 min in doses of 10 and 20 mg/kg/h during both the digestive and interdigestive states. It was found that pinaverium bromide strongly inhibited gastrointestinal contractile activity during both the digestive and interdigestive states; contractions in the stomach were most strongly inhibited; however, those in the small and large bowels were also significantly inhibited. No significant side effects in the circulatory and respiratory systems and the gastrointestinal tract such as nausea, vomiting or diarrhea were observed during and after the infusion of this agent. PMID:7197953

  13. [Distigmine bromide improves chronic intestinal pseudo-obstruction in a case of MELAS].

    PubMed

    Nakae, Yoshiharu; Kishida, Hitaru; Hakii, Yasuhito; Koyano, Shigeru; Suzuki, Yume; Kuroiwa, Yoshiyuki

    2007-04-01

    A 34-year-old man with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) showed chronic intestinal pseudo-obstruction (CIPO), which was improved by the administration of distigmine bromide. He exhibited generalized tonic clonic seizures at the age of 21, and mitochondrial DNA analysis showed the MELAS mutation. At the age of 34, he became akinetic mutism after nonconvulsive status epilepticus and needed enteral nutrition through a nasogasrtic tube. However, he developed abdominal distention and vomiting, and was diagnosed as CIPO, therefore tube feeding was stopped. Although the administration of domperidone, mosapride citrate, butyric acid bacteria, sodium picosulfate, prostaglandin F2 alpha, pantothenic acid, dioctyl sodium sulfosuccinate, and so on, was ineffective, the administration of distigmine bromide improved his bowel motion disturbance and abnormal distention. The present case is the first MELAS patient with CIPO to be ameliorated by distigmine bromide, which might work acetylcholine receptor on the interstitial cells of Cajal. PMID:17511291

  14. Effect of chloramphenicol and ethidium bromide on the level of ornithine carbamoyltransferase in Neurospora crassa

    SciTech Connect

    Zerez, C.R.; Weiss, R.L.

    1986-05-01

    The specific activity of the nuclear-gene-encoded, mitochondrial arginine biosynthetic enzyme ornithine carbamoyltransferase in Neurospora crassa was elevated in mycelia treated with chloramphenicol or ethidium bromide. The increase in specific activity was caused by an increase in the number of mature enzyme molecules rather than by the activation of a preexisting enzyme. Chloramphenicol and ethidium bromide appeared to act indirectly via arginine-mediated derepression. However, derepression did not appear to result from a drug-mediated decrease in the arginine pool.

  15. Lithium Bromide/Water as Additives in Dearomatizing Samarium-Ketyl (Hetero)Arene Cyclizations.

    PubMed

    Rao, Chintada Nageswara; Bentz, Christoph; Reissig, Hans-Ulrich

    2015-11-01

    New conditions for dearomatizing samarium-ketyl (hetero)arene cyclizations are reported. In many examples of these samarium diiodide-mediated reactions, lithium bromide and water can be used as additives instead of the carcinogenic and mutagenic hexamethylphosphoramide (HMPA). The best results were obtained for the cyclizations of N-acylated indole derivatives delivering the expected indolines in good yields and excellent diastereoselectivities. A new type of cyclization delivering indolyl-substituted allene derivatives is also described. The scope and limitations of the lithium bromide/water system are discussed. PMID:26368916

  16. The determination of molecular weights of biologically active proteins by cetyltrimethylammonium bromide-polyacrylamide gel electrophoresis.

    PubMed

    Akin, D T; Shapira, R; Kinkade, J M

    1985-02-15

    A novel cetyltrimethylammonium bromide-polyacrylamide gel electrophoresis system which is useful for the separation of native forms of proteins consistent with their molecular weights is reported here. Many proteins examined in this system demonstrated the same association patterns which have been shown by other techniques to exist under nondenaturing conditions. In addition, biological activity could be assayed directly in the gel after electrophoresis. Based on the peculiar characteristics of cetyltrimethylammonium bromide, a possible explanation which may account for the behavior of proteins in this system is presented. PMID:4003759

  17. Bromide, Chloride, and Sulfate Concentrations, and Specific Conductance, Lake Texoma, Texas and Oklahoma, 2007-08

    USGS Publications Warehouse

    Baldys, Stanley

    2009-01-01

    The U.S. Geological Survey, in cooperation with the City of Dallas Water Utilities Division, collected water-quality data from 11 sites on Lake Texoma, a reservoir on the Texas-Oklahoma border, during April 2007-September 2008. At 10 of the sites, physical properties (depth, specific conductance, pH, temperature, dissolved oxygen, and alkalinity) were measured and samples were collected for analysis of selected dissolved constituents (bromide, calcium, magnesium, potassium, sodium, carbonate, bicarbonate, chloride, and sulfate); at one site, only physical properties were measured. The primary constituent of interest was bromide. Bromate can form when ozone is used to disinfect raw water containing bromide, and bromate is a suspected human carcinogen. Chloride and sulfate were of secondary interest. Only the analytical results for bromide, chloride, sulfate, and measured specific conductance are discussed in this report. Median dissolved bromide concentrations ranged from 0.28 to 0.60 milligrams per liter. The largest median dissolved bromide concentration (0.60 milligram per liter at site 11) was from the Red River arm of Lake Texoma. Dissolved bromide concentrations generally were larger in the Red River arm of Lake Texoma than in the Washita arm of the lake. Median dissolved chloride concentrations were largest in the Red River arm of Lake Texoma at site 11 (431 milligrams per liter) and smallest at site 8 (122 milligrams per liter) in the Washita arm. At site 11 in the Red River arm, the mean and median chloride concentrations exceeded the secondary maximum contaminant level of 300 milligrams per liter for chloride established by the 'Texas Surface Water Quality Standards' for surface-water bodies designated for the public water supply use. Median dissolved sulfate concentrations ranged from 182 milligrams per liter at site 4 in the Big Mineral arm to 246 milligrams per liter at site 11 in the Red River arm. None of the mean or median sulfate concentrations

  18. Improved light olefin yield from methyl bromide coupling over modified SAPO-34 molecular sieves.

    PubMed

    Zhang, Aihua; Sun, Shouli; Komon, Zachary J A; Osterwalder, Neil; Gadewar, Sagar; Stoimenov, Peter; Auerbach, Daniel J; Stucky, Galen D; McFarland, Eric W

    2011-02-21

    As an alternative to the partial oxidation of methane to synthesis gas followed by methanol synthesis and the subsequent generation of olefins, we have studied the production of light olefins (ethylene and propylene) from the reaction of methyl bromide over various modified microporous silico-aluminophosphate molecular-sieve catalysts with an emphasis on SAPO-34. Some comparisons of methyl halides and methanol as reaction intermediates in their conversion to olefins are presented. Increasing the ratio of Si/Al and incorporation of Co into the catalyst framework improved the methyl bromide yield of light olefins over that obtained using standard SAPO-34. PMID:21203621

  19. Active Control of Interface Shape During the Crystal Growth of Lead Bromide

    NASA Technical Reports Server (NTRS)

    Duval, W. M. B.; Batur, C.; Singh, N. B.

    2003-01-01

    A thermal model for predicting and designing the furnace temperature profile was developed and used for the crystal growth of lead bromide. The model gives the ampoule temperature as a function of the furnace temperature, thermal conductivity, heat transfer coefficients, and ampoule dimensions as variable parameters. Crystal interface curvature was derived from the model and it was compared with the predicted curvature for a particular furnace temperature and growth parameters. Large crystals of lead bromide were grown and it was observed that interface shape was in agreement with the shape predicted by this model.

  20. Breakdown of ionic character of molecular alkali bromides in inner-valence photoionization

    SciTech Connect

    Karpenko, A. Iablonskyi, D.; Kettunen, J. A.; Cao, W.; Huttula, M.; Aksela, H.; Urpelainen, S.

    2014-05-28

    The inner-valence region of alkali bromide XBr (X=Li, Na, K, Rb) vapours has been studied experimentally by means of synchrotron radiation excited photoelectron spectroscopy. Experimental spectra were analyzed by comparing them with available theoretical results and previous experiments. Ionic character of alkali bromides is seen to change in the inner-valence region with increasing atomic number of the alkali atom. A mechanism involving mixing between Br 4s and Rb 4p orbitals has been suggested to account for the fine structure observed in inner-valence ionization region of RbBr.

  1. 78 FR 14508 - Notice of Affirmation of Addition of a Treatment Schedule for Methyl Bromide Fumigation of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... Treatment Schedule for Methyl Bromide Fumigation of Cottonseed AGENCY: Animal and Plant Health Inspection... methyl bromide fumigation of cottonseed for the fungal plant pathogen Fusarium oxysporum f. sp... Manual of the treatment described in the notice published at 77 FR 31564-31566 on May 29, 2012....

  2. Cu(OAc)2-Et3N mediated oxidative coupling of α-azido ketones with pyridinium ylides: utilizing in situ generated imines for regioselective synthesis of imidazo[1,2-a]pyridines.

    PubMed

    Kamal, Ahmed; Reddy, Chada Narsimha; Satyaveni, Malasala; Chandrasekhar, D; Nanubolu, Jagadeesh Babu; Singarapu, Kiran Kumar; Maurya, Ram Awatar

    2015-07-01

    Phenacyl azides were reacted with pyridinium ylides in the presence of Cu(OAc)2 (2 mol%) and Et3N utilizing molecular oxygen as a green oxidant to yield imidazo[1,2-a]pyridines in exclusive regioselectivity. Following the optimized protocol, 28 different fused heterocycles were synthesized in high yields (71-92%). In order to get mechanistic insight into the reaction, a few control experiments were carried out and the role of the copper salt was discussed. PMID:26027651

  3. OZONATION BYPRODUCTS: IDENTIFICATION OF BROMOHYDRINS FROM THE OZONATION OF NATURAL WATERS WITH ENHANCED BROMIDE LEVELS

    EPA Science Inventory

    When ozone is used in the treatment of drinking water, it reacts with both inorganic and organic compounds to form byproducts. f bromide is present, it may be oxidized to hydrobromous acid, which may than react with natural organic matter to form brominated organic compounds. he ...

  4. Experimental study of negative temperatures in lithium-bromide absorption refrigerating machines

    NASA Astrophysics Data System (ADS)

    Stepanov, K. I.; Mukhin, D. G.; Alekseenko, S. V.; Volkova, O. V.

    2015-07-01

    The authors have developed a method and presented experimental data for obtaining negative temperatures of evaporation in lithium-bromide absorption chillers driven by heat recovery. It has been found that the attainable temperature of the refrigerated medium is the value of -5 °C.

  5. Palladium-catalyzed carbonylative synthesis of quinazolinones from 2-aminobenzamide and aryl bromides.

    PubMed

    Wu, Xiao-Feng; He, Lin; Neumann, Helfried; Beller, Matthias

    2013-09-16

    C from CO! A straightforward procedure for the carbonylative synthesis of quinazolinones from readily available 2-aminobenzamide and aryl bromides has been developed. In the presence of a palladium catalyst, various quinazolinones were produced in moderate to excellent yields. Remarkably, no chromatography was needed for purification (see scheme). PMID:24175339

  6. WEED COMMUNITY COMPOSITION IN TREE FRUIT NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several agricultural cropping systems, for decades, have relied on methyl bromide (MeBr) for pest control including weeds. Alternative fumigants are being sought worldwide because MeBr has been identified as an ozone-layer depleting substance. Weed communities respond dynamically to alterations in...

  7. 78 FR 36507 - Notice of Availability of a Treatment Evaluation Document; Methyl Bromide Fumigation of Blueberries

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-18

    ...We are advising the public that we have determined that it is necessary to immediately add to the Plant Protection and Quarantine Treatment Manual an additional treatment schedule for methyl bromide fumigation of blueberries for Mediterranean fruit fly and South American fruit fly. We have prepared a treatment evaluation document that describes the new treatment schedule and explains why we......

  8. WATER AND BROMIDE RECOVERY IN WICK AND PAN LYSIMETERS UNDER CONVENTIONAL AND ZERO TILLAGE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying in situ solute transport through soils and the landscape has been widely acknowledged as important and yet challenging. The objective of this study was to evaluate water and bromide movement in no-tilled (NT) and conventionally tilled (CT) corn using two different types of in situ lysime...

  9. BROMIDES'S EFFECT ON DBP FORMATION, SPECIATION, AND CONTROL: PART 1, OZONATION

    EPA Science Inventory

    Many factors should be taken into account in the assessment of the impact of ozonation on the speciation of the THMs and HAAS. n this study, the behavior of the individual species with varying bromide and ozone concentrations was examined. n general, the formation behavior for th...

  10. PERENNIAL CROP NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS: EFFECT ON WEED COMMUNITY COMPOSTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed communities can respond dynamically to shifts in management systems. Thus, transition from methyl bromide (MeBr) to alternative fumigants for pre-plant soil treatments may cause shifts in weed species composition. This hypothesis was tested in four perennial crop nurseries in California. The...

  11. Mechanism of HERG potassium channel inhibition by tetra-n-octylammonium bromide and benzethonium chloride

    PubMed Central

    Long, Yan; Lin, Zuoxian; Xia, Menghang; Zheng, Wei; Li, Zhiyuan

    2016-01-01

    Tetra-n-octylammonium bromide and benzethonium chloride are synthetic quaternary ammonium salts that are widely used in hospitals and industries for the disinfection and surface treatment and as the preservative agent. Recently, the activities of HERG channel inhibition by these compounds have been found to have potential risks to induce the long QT syndrome and cardiac arrhythmia, although the mechanism of action is still elusive. This study was conducted to investigate the mechanism of HERG channel inhibition by these compounds using whole-cell patch clamp experiments in a CHO cell line stably expressing HERG channels. Tetra-n-octylammonium bromide and benzethonium chloride exhibited concentration-dependent inhibitions of HERG channel currents with IC50 values of 4 nM and 17 nM, respectively, which were also voltage-dependent and use-dependent. Both compounds shifted the channel activation I-V curves in a hyperpolarized direction for 10-15 mV and accelerated channel activation and inactivation processes by 2-fold. In addition, tetra-n-octylammonium bromide shifted the inactivation I-V curve in a hyperpolarized direction for 24.4 mV and slowed the rate of channel deactivation by 2-fold, whereas benzethonium chloride did not. The results indicate that tetra-n-octylammonium bromide and benzethonium chloride are open-channel blockers that inhibit HERG channels in the voltage-dependent, use-dependent and state-dependent manners. PMID:23313619

  12. Mild Pd-Catalyzed Aminocarbonylation of (Hetero)Aryl Bromides with a Palladacycle Precatalyst

    PubMed Central

    2015-01-01

    A palladacyclic precatalyst is employed to cleanly generate a highly active XantPhos-ligated Pd-catalyst. Its use in low temperature aminocarbonylations of (hetero)aryl bromides provides access to a range of challenging products in good to excellent yields with low catalyst loading and only a slight excess of CO. Some products are unattainable by traditional carbonylative coupling. PMID:25090373

  13. Methyl bromide and sulfuryl fluoride effectiveness against red flour beetle life stages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of methyl bromide (MB) and sulfuryl fluoride (SF) for managing all life stages of the red flour beetle, Tribolium castaneum, was investigated in the Hal Ross Flour Mill at Kansas State University. Eggs, young larvae, large larvae, pupae, and adults confined in plastic compartments with ...

  14. Bromate formation from bromide oxidation by the UV/persulfate process.

    PubMed

    Fang, Jing-Yun; Shang, Chii

    2012-08-21

    Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the bromate formation increased with increasing persulfate dosage and bromide concentration. The bromate formation was initiated and primarily driven by sulfate radicals (SO(4)(•-)) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr(-)) as an intermediate and bromate as the final product. Under the test conditions, the rate of the first step driven by SO(4)(•-) is slower than that of the second step. Direct UV photolysis of HOBr/OBr(-) to form bromate and the photolysis of bromate are insignificant. The bromate formation was similar for pH 4-7 but decreased over 90% with increasing pH from 7 to above 9. Less bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine atoms, HOBr/OBr(-) and SO(4)(•-). The extent of bromate formation and degradation of micropollutants are nevertheless coupled processes unless intermediate bromine species are consumed by NOM in real water. PMID:22831804

  15. Kinetics and mechanism of the oxidation of bromide by periodate in aqueous acidic solution.

    PubMed

    Szél, Viktor; Csekő, György; Horváth, Attila K

    2014-11-13

    The periodate–bromide reaction has been studied spectrophotometrically mainly in excess of bromide ion, monitoring the formation of the total amount of bromine at 450 nm at acidic buffered conditions and at a constant ionic strength in the presence of a phosphoric acid/dihydrogen phosphate buffer. The stoichiometry of the reaction was established to be strictly IO4(–) + 2Br(–) + 2H(+) → Br2 + IO3(–) + H2O. The formal kinetic order of the reactants was found to be perfectly one and two in the cases of periodate and bromide, respectively, but that of the hydrogen ion lies between one and two. We have also provided experimental evidence that dihydrogen phosphate accelerates the formation of bromine, suggesting the appearance of strong buffer assistance. On the basis of the experiments, a simple two-step kinetic model is proposed involving BrIO3 as a key intermediate that perfectly explains all of the experimental findings. Furthermore, we have also shown that in huge excess of bromide, the apparent rate coefficient obtained from the individual curve fitting method of the absorbance–time series is necessarily independent of the initial periodate concentration that may falsely be interpreted as the rate of bromine formation is also independent of the concentration of periodate. PMID:25365468

  16. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Ethanaminium, N- -N-ethyl-, bromide. 721.4090 Section 721.4090 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4090 Ethanaminium,...

  17. Status of methyl bromide alternatives for ornamental crop production in Florida and California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The phase-out of methyl bromide presents critical challenges to producers of cut-flowers and in-ground ornamentals. Work in California and Florida has included combinations of chemicals, various formulations, and application methods for registered compounds, including 1,3-dichloropropene (1,3-D), ch...

  18. Comparing copper sulfate, diquat bromide, formalin, and hydrogen peroxide treatments on channel catfish eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reduced fish egg survival is often associated with fungal infestation (Saprolegnia spp.) of the eggs. Chemical treatments have been used to limit these infestations on fish eggs and increase survival. The effect of copper sulfate (10 mg/L), diquat bromide (25 mg/L diquat cation), formalin (433 mg/...

  19. Methods to facilitate the adoption of alternatives to methyl bromide soil fumigation by California strawberry growers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this project is to facilitate the adoption of strawberry production systems that do not use methyl bromide (MB). The five year project initially focused on fumigant alternatives to MB. The project has resulted in increased use of barrier films that reduce fumigant emission. The focus s...

  20. TRIBROMOPYRROLE, BROMINATED ACIDS, AND OTHER DISINFECTION BYPRODUCTS PRODUCED BY DISINFECTION OF DRINKING WATER RICH IN BROMIDE

    EPA Science Inventory

    Using gas chromatography/mass spectrometry (GC/MS), we investigated the formation of disinfection byproducts (DBPs) from high bromide waters (2 mg/L) treated with chlorine or chlorine dioxide used in combination with chlorine and chloramines. This study represents the first comp...

  1. Photoredox-Catalyzed Bromodifluoromethylation of Alkenes with (Difluoromethyl)triphenylphosphonium Bromide.

    PubMed

    Lin, Qing-Yu; Ran, Yang; Xu, Xiu-Hua; Qing, Feng-Ling

    2016-05-20

    Under visible-light photoredox conditions, difluoromethyltriphenylphosphonium bromide was used as the precursor of the CF2H radical for bromodifluoromethylation of alkenes. The presence of catalytic CuBr2 resulted in the selective formation of the bromodifluoromethylated products. PMID:27136958

  2. Steam disinfestation as a methyl bromide alternative in California cut flower nurseries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Steam may be an effective alternative to methyl bromide in cut flower production in California. Advantages of steam include broad spectrum pest control and a zero hour re-entry interval. The principle disadvantage of sheet steaming is cost effectiveness due to current energy prices and application...

  3. Effect of increasing bromide concentration on toxicity in treated drinking water.

    PubMed

    Sawade, Emma; Fabris, Rolando; Humpage, Andrew; Drikas, Mary

    2016-04-01

    Research is increasingly indicating the potential chronic health effects of brominated disinfection by-products (DBPs). This is likely to increase with elevated bromide concentrations resulting from the impacts of climate change, projected to include extended periods of drought and the sudden onset of water quality changes. This will demand more rigorous monitoring throughout distribution systems and improved water quality management at water treatment plants (WTPs). In this work the impact of increased bromide concentration on formation of DBPs following conventional treatment and chlorination was assessed for two water sources. Bioanalytical tests were utilised to determine cytotoxicity of the water post disinfection. Coagulation was shown to significantly reduce the cytotoxicity of the water, indicating that removal of natural organic matter DBP precursors continues to be an important factor in drinking water treatment. Most toxic species appear to form within the first half hour following disinfectant addition. Increasing bromide concentration across the two waters was shown to increase the formation of trihalomethanes and shifted the haloacetic acid species distribution from chlorinated to those with greater bromine substitution. This correlated with increasing cytotoxicity. This work demonstrates the challenges faced by WTPs and the possible effects increasing levels of bromide in source waters could have on public health. PMID:27105403

  4. The use of agricultural by-products to capture methyl bromide following post-harvest fumigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Activated carbons were prepared from plum and peach stone as well as almond and walnut shell and comparatively evaluated as sorbents to minimize the atmospheric emission of methyl bromide following postharvest fumigations. A variety of methods were used to make the activated carbons and each is desc...

  5. Copper-catalyzed conversion of aryl and heteroaryl bromides into the corresponding chlorides.

    PubMed

    Feng, Xiujuan; Qu, Yiping; Han, Yanlei; Yu, Xiaoqiang; Bao, Ming; Yamamoto, Yoshinori

    2012-10-01

    An efficient method for the synthesis of aryl and heteroaryl chlorides is described. The reactions of aryl and heteroaryl bromides with tetramethylammonium chloride proceeded smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding chlorides in satisfactory to excellent yields. PMID:22895409

  6. The stereoselective synthesis of dienes through dehalogenative homocoupling of terminal alkenyl bromides on Cu(110).

    PubMed

    Sun, Qiang; Cai, Liangliang; Ma, Honghong; Yuan, Chunxue; Xu, Wei

    2016-05-21

    We have successfully achieved the stereoselective synthesis of a specific cis-diene moiety through a dehalogenative homocoupling of alkenyl bromides on the Cu(110) surface, where the formation of a cis-form organometallic intermediate is the key to such a stereoselectivity as determined by DFT calculations. PMID:27063567

  7. Fumigant use and transition from methyl bromide to alternatives in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reports fumigant use status and changes in response to the phase-out of methyl bromide (MeBr) and transition to alternative chemicals based on the 2010 Pesticide Use Reporting (PUR) database compiled by California Department of Pesticide Regulation. The data were analyzed from 2000 throug...

  8. 77 FR 29341 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-17

    ... part 2 subpart B; 41 FR 36752, 43 FR 40000, 50 FR 51661. If no claim of confidentiality accompanies the... to the provisions of the Montreal Protocol on Substances that Deplete the Ozone Layer for... AGENCY Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption...

  9. Methyl bromide release from activated carbon and the soil/water/carbon interface

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl Bromide (MB) is a major source of stratospheric bromine radical, a known depletor of ozone. The use of ozone-depleting chemicals, including MB, is regulated by the Montreal Protocol. Critical uses of MB are permitted, such as when postharvest fumigation is mandated by an importing country. Fo...

  10. EVALUATION OF CONTAINMENT AND CONTROL OPTIONS FOR METHYL BROMIDE IN COMMODITY TREATMENT

    EPA Science Inventory

    The report gives results of an investigation of means for methyl bromide (MeBr) recovery, reuse, and destruction to prevent atmospheric emissions if its limited use were still allowed. (NOTE: MeBr is an ozone-depleting chemical scheduled to be phased out by the Clean Air Act by t...

  11. 77 FR 31564 - Notice of Availability of a Treatment Evaluation Document; Methyl Bromide Fumigation of Cottonseed

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... Federal Register on April 6, 2012 (77 FR 20752-20756), EPA proposed to reinstate the tolerance of methyl...; Methyl Bromide Fumigation of Cottonseed AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION... add to the Plant Protection and Quarantine Treatment Manual a treatment schedule for methyl...

  12. Headspace gas chromatographic method for determination of methyl bromide in food ingredients

    SciTech Connect

    DeVries, J.W.; Broge, J.M.; Schroeder, J.P.; Bowers, R.H.; Larson, P.A.; Burns, N.M.

    1985-11-01

    A headspace gas chromatographic (GC) method, which can be automated, has been developed for determination of methyl bromide. This method has been applied to wheat, flour, cocoa, and peanuts. Samples to be analyzed are placed in headspace sample vials, water is added, and the vials are sealed with Teflon-lined septa. After an appropriate equilibration time at 32 degrees C, the samples are analyzed within 10 h. A sample of the headspace is withdrawn and analyzed on a gas chromatograph equipped with an electron capture detector (ECD). Methyl bromide levels were quantitated by comparison of peak area with a standard. The standard was generated by adding a known amount of methyl bromide to a portion of the matrix being analyzed and which was known to be methyl bromide free. The detection limit of the method was 0.4 ppb. The coefficient of variation (CV) was 6.5% for wheat, 8.3% for flour, 3.3% for cocoa, and 11.6% for peanuts.

  13. Recovery of bromine from methyl bromide using amorphous MnO{sub x} photocatalysts

    SciTech Connect

    Lin, Jung-Chou; Suib, S.L.; Cutlip, M.B.

    1996-07-01

    Amorphous MnO{sub x} (AMO) has been prepared by the reaction of potassium permanganate and oxalic acid. Surface area measurements and pore size distribution analyses show that AMO has high surface (200 m{sup 2}/g) area and a microporous structure. Kinetic results indicate that methyl bromide degradation using AMO photocatalysts is due to a combination of thermocatalytic and photocatalytic reactions; however, the photocatalytic reaction is predominant. Detailed studies show that both molecular oxygen and bulk lattice oxygen of AMO can be involved in the oxidation of methyl bromide to carbon dioxide. Kinetic data, Auger analyses, and FTIR spectra suggest that both oxidation state changes of Mn and the presence of bromide adsorbed on the surface might lead to deactivation of the catalyst. According to mass balance calculations and analyses with potassium iodide solutions with starch, the final products are bromine, carbon dioxide, and water. The overall reaction for methyl bromide degradation under illumination using AMO photocatalyst can be expressed as CH{sub 3}Br{sub (g)} + 7/4O{sub 2(g)} {yields} CO{sub 2(g)} + 3/2H{sub 2}O(g) + {1/2}Br{sub 2(g)}. 27 refs., 10 figs., 2 tabs.

  14. Quantitative gas chromatographic mass spectrometric determination of pinaverium-bromide in human serum.

    PubMed

    de Weerdt, G A; Beke, R P; Verdievel, H G; Barbier, F; Jonckheere, J A; de Leenheer, A P

    1983-03-01

    A method has been developed for quantitative determination of pinaverium-bromide, a quaternary ammonium derivative with papaverine-like activity, in human serum. The method involves a chloroform extraction of serum spiked with N-(6,6-dimethyl bicyclo[3.1.1]2-heptenyl-ethoxyethyl) perhydro-1,4-oxazine as internal standard. After evaporation of the solvent, and reduction of the residue with Raney-Nickel, the internal standard and the reduced pinaverium-bromide are re-extracted from the reaction mixture with toluene and analysed isothermally on a fused silica column coated with OV-101. Although chemical ionization with methane revealed intense protonated molecular ions for both pinaverium-bromide and the internal standard, selectivity and sensitivity were significantly lower in comparison with electron impact ionization at 70 e V. Therefore, quantification was performed in the electron impact mode by single ion monitoring of the common fragment ion at m/z 100.2. A linear detector response was observed up to 160 ng ml-1. A within-run assay precision better than 2% CV (n = 5) was found, and a detection limit of 1 ng pinaverium-bromide ml-1 of serum was attained. PMID:6850068

  15. Combinatorial electrochemistry using metal nanoparticles: from proof-of-concept to practical realisation for bromide detection.

    PubMed

    Sljukić, Biljana; Baron, Ronan; Salter, Chris; Crossley, Alison; Compton, Richard G

    2007-05-01

    Principles and practical application of combinatorial electrochemistry in search for new electroactive materials in electroanalysis have been explored. Nanoparticles of three different metals: silver, gold and palladium have been independently synthesized on the glassy carbon spherical powder surface by electroless deposition process and characterized using both spectroscopic and electrochemical techniques. These three materials were then combined together onto basal plane pyrolytic graphite electrode surface and the application of the combinatorial approach to find the electrode material for bromide detection as model target analyte was demonstrated. The component electroactive for bromide detection was next identified and it was found that silver nanoparticles were the active ones. A composite electrode based on silver nanoparticle modified glassy carbon powder and epoxy resin was then fabricated and it was found to allow accurate determination of bromide. The electroactivity for the bromide determination of the composite electrode was compared with that of a bulk silver electrode and it was shown that the composite electrode is very efficient with a comparable electroactivity with only a portion of precious metals being used for its construction. PMID:17416224

  16. Reduced rates and alternatives to methyl bromide for snapdragon production in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A field trial was conducted to evaluate soil solarization, Midas™ (iodomethane:chloropicrin 50:50, Arysta LifeScience Corp., Cary, NC) and different rates and formulations of methyl bromide under standard and metalized films for the production of snapdragon (Antirrhinum majus) in Martin County, Flor...

  17. Comparison of Shank-and-Drip-Applied Methyl Bromide Alternatives in Perenial Crop Field Nurseries.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide has been used extensively at open-field perennial crop nurseries to ensure the production of plants that are free of soilborne pests and pathogens. California regulations require that nursery stock for farm planting be commercially clean with respect to economically important nematod...

  18. Forest nurseries face critical choices with the loss of methyl bromide fumigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forest nurseries in the western United States have relied for decades on methyl bromide for the control of soilborne pathogens such as Cylindrocarpoin, Fusarium, and Pythium species that affect bareroot tree seedling production. However, increased state and federal regulations have led to a substan...

  19. 76 FR 7200 - Methyl Bromide; Notice of Receipt of Requests To Voluntarily Amend Registrations To Terminate...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ... Hawaii (use allowed until December 31, 2012); (2) soils on golf courses and athletic/recreational fields..., Vidalia onions grown in Georgia, ginger grown in Hawaii; (2) soils on golf courses and athletic... bromide on soil for resurfacing/replanting turf or sod on golf courses and athletic/recreational...

  20. Methyl Bromide Alternatives Area-Wide Pest Management Project - South Atlantic Progress Report

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protocols and Standard Operational Procedures (SOPs) were developed for collecting environmental and soil edaphic information during and after application of methyl bromide alternatives. Parameters measured included soil moisture, soil bulk density, percent moisture at field capacity (-0.3 bars wat...

  1. IDENTIFICATION OF NEW DRINKING WATER DISINFECTION BY-PRODUCTS FORMED IN THE PRESENCE OF BROMIDE

    EPA Science Inventory

    Using a combination of mass spectrometry and infrared spectroscopy, disinfection by-products (DBPs) were identified in ozonated drinking water containing elevated bromide levels, and in ozonated water treated with secondary chlorine or chloramine. Only one brominated by-product-d...

  2. Potential environmental neurotoxins related to 1-methyl-4-phenylpyridinium: Selective toxicity of 1-methyl-4-(4'-acetamidophenyl)-pyridinium and 1-methyl-4-cyclohexylpyridinium for dopaminergic neurons in culture

    SciTech Connect

    Michel, P.P.; Dandapani, B.K.; Efange, S.M.; Hefti, F. )

    1990-05-01

    Mesencephalic cells in culture were exposed to various compounds which we hypothesized to be selective toxins for dopaminergic neurons. The culture system was previously shown suitable for assessing selective dopaminergic neurotoxicity, since 1-methyl-4-phenyl-pyridinium (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridinium, destroyed dopaminergic neurons without affecting other cells. Some compounds tested were selected to fulfill two criteria believed to underly the selective dopaminergic neurotoxicity of MPP+, i.e., to be a potential substrate for the uptake carrier for dopamine and to possess a strong delocalized positive charge to inhibit the mitochondrial respiratory system. Other compounds were chosen on the basis of clinical or anecdotal evidence linking them to Parkinson's disease. Among the tested compounds two pyridinium analogs, 1-methyl-4-(4'-acetamidophenyl)pyridinium (MACPP+) and 1-methyl-4-cyclohexylpyridinium (MCP+) were found to be selectively toxic toward dopaminergic neurons. Incubation of cultures with both MACPP+ and MCP+ produced a dramatic reduction in the number of tyrosine hydroxylase-positive cells and the uptake of (3H)dopamine without reducing the number of cells visualized by phase-contrast microscopy or the uptake of (3H)aminobutyric acid. Besides MACPP+ and MCP+ none of the tested compounds exhibited any selective dopaminergic neurotoxicity. Together with earlier findings, these data suggest that the structural requirements are rather strict for a chemical to be a selective dopaminergic neurotoxin and make it unlikely that there is a wide spectrum of environmental dopaminergic toxins.

  3. Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels.

    PubMed

    Sánchez-Polo, M; Rivera-Utrilla, J; Salhi, E; von Gunten, U

    2006-08-01

    The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value ( [Formula: see text] ), whereas the volume of meso-(V(2)) and macropores (V(3)) decreased slightly. Chemical characterization of the materials revealed that carbonization and especially activation process considerably increased the surface basicity of the sample. Original sample (A) presented acidic surface properties (pH(PZC)=4.5) with 21% surface oxygen, whereas the sample that underwent activation showed mainly basic surface chemical properties (pH(PZC)=9.5) with only 6% of surface oxygen. Carbonization and especially, activation process considerable increased the adsorption capacity of bromide and iodide ions. This would mainly be produced by (i) an increase in the microporosity of the sample, which increases Ag-adsorption sites available to halide anions, and (ii) a rise of the basicity of the sample, which produces an increase in attractive electrostatic interactions between the aerogel surface, positively charged at the working pH (pH(solution)bromide and iodide was studied under dynamic conditions using waters from Lake Zurich. Results obtained showed that the carbonization and activation processes increased the adsorptive capacity of the aerogel sample. However, results showed that the adsorption capacity of the aerogel samples studied was considerably lower in water from Lake Zurich. Results showed X(0.02) (amount adsorbed to initial breakthrough) values of 0.1 and 4.3 mg/g for chloride anion and dissolved organic carbon (DOC), respectively, during bromide adsorption process in water from Lake Zurich

  4. Kinetics of Chlorination of Benzophenone-3 in the Presence of Bromide and Ammonia.

    PubMed

    Abdallah, Pamela; Deborde, Marie; Dossier Berne, Florence; Karpel Vel Leitner, Nathalie

    2015-12-15

    The aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia. PMID:26587868

  5. A novel explicit approach to model bromide and pesticide transport in connected soil structures

    NASA Astrophysics Data System (ADS)

    Klaus, J.; Zehe, E.

    2011-07-01

    The present study tests whether an explicit treatment of worm burrows and tile drains as connected structures is feasible for simulating water flow, bromide and pesticide transport in structured heterogeneous soils at hillslope scale. The essence is to represent worm burrows as morphologically connected paths of low flow resistance in a hillslope model. A recent Monte Carlo study (Klaus and Zehe, 2010, Hydrological Processes, 24, p. 1595-1609) revealed that this approach allowed successful reproduction of tile drain event discharge recorded during an irrigation experiment at a tile drained field site. However, several "hillslope architectures" that were all consistent with the available extensive data base allowed a good reproduction of tile drain flow response. Our second objective was thus to find out whether this "equifinality" in spatial model setups may be reduced when including bromide tracer data in the model falsification process. We thus simulated transport of bromide for the 13 spatial model setups that performed best with respect to reproduce tile drain event discharge, without any further calibration. All model setups allowed a very good prediction of the temporal dynamics of cumulated bromide leaching into the tile drain, while only four of them matched the accumulated water balance and accumulated bromide loss into the tile drain. The number of behavioural model architectures could thus be reduced to four. One of those setups was used for simulating transport of Isoproturon, using different parameter combinations to characterise adsorption according to the Footprint data base. Simulations could, however, only reproduce the observed leaching behaviour, when we allowed for retardation coefficients that were very close to one.

  6. Utility of Bromide and Heat Tracers for Aquifer Characterization Affected by Highly Transient Flow Conditions

    SciTech Connect

    Ma, Rui; Zheng, Chunmiao; Zachara, John M.; Tonkin, Matthew J.

    2012-08-29

    A tracer test using both bromide and heat tracers conducted at the Integrated Field Research Challenge site in Hanford 300 Area (300A), Washington, provided an instrument for evaluating the utility of bromide and heat tracers for aquifer characterization. The bromide tracer data were critical to improving the calibration of the flow model complicated by the highly dynamic nature of the flow field. However, most bromide concentrations were obtained from fully screened observation wells, lacking depth-specific resolution for vertical characterization. On the other hand, depth-specific temperature data were relatively simple and inexpensive to acquire. However, temperature-driven fluid density effects influenced heat plume movement. Moreover, the temperature data contained “noise” caused by heating during fluid injection and sampling events. Using the hydraulic conductivity distribution obtained from the calibration of the bromide transport model, the temperature depth profiles and arrival times of temperature peaks simulated by the heat transport model were in reasonable agreement with observations. This suggested that heat can be used as a cost-effective proxy for solute tracers for calibration of the hydraulic conductivity distribution, especially in the vertical direction. However, a heat tracer test must be carefully designed and executed to minimize fluid density effects and sources of noise in temperature data. A sensitivity analysis also revealed that heat transport was most sensitive to hydraulic conductivity and porosity, less sensitive to thermal distribution factor, and least sensitive to thermal dispersion and heat conduction. This indicated that the hydraulic conductivity remains the primary calibration parameter for heat transport.

  7. [Effectiveness of pinaverium bromide therapy on colonic motility disorders in irritable bowel syndrome].

    PubMed

    Wittmann, T; Fehér, A; Rosztóczy, A; Jánosi, J

    1999-02-28

    The special patterns of the slow wave activity in irrittable bowel syndrome by means of surface electromyography were examined and the effect of pinaverium bromide on the symptoms and on the colonic motility in this disease was estimated. Twenty two patients with irritable bowel syndrome and 7 healthy controls were selected to the study. The clinical symptoms were abdominal pain and bloating in all patients, constipation in 9, and diarrhoea in 6 cases. Surface electromyography was carried out before and on the 14th day of the treatment with pinaverium bromide (50 mg t. i. d). The colonic motility was analysed in a 2 hour fasting and a 2 hour postprandial period following a standard (800 kCal) meal. The slow wave frequency of 0.01-0.04 Hz were selected and analysed. The mean frequency of activity peaks (n/10 min) and power-index (area under curve, microV 10 min) were measured. For statistical analysis Student's t-test was applied. Electromyogram of patients with irritable bowel syndrome showed a significant increase of the measured colonic motility parameters both in fasting and postprandial states. Fourteen days of pinaverium bromide treatment was able to significantly reduce the intensity of the colonic motor activity. Administration of pinaverium bromide completely released in 6 and significantly improved the abdominal pain in other 12 patients, while the bloating disappeared in 12 and was significantly improved in 5 from 22 patients. Pinaverium bromide was able to normalise the stool frequency: the weekly number of stools was decreased from 16 to 7 in the patients complaining diarrhoea ant it was increased from 2 to 6 in the patients with constipation. PMID:10204402

  8. The role of bromide ions in seeding growth of Au nanorods.

    PubMed

    Garg, Niti; Scholl, Clark; Mohanty, Ashok; Jin, Rongchao

    2010-06-15

    We report our findings on the important role of bromide ions in the seeding growth process of Au nanorods. The seed-mediated process constitutes a well-developed method for synthesizing gold nanorods in high yield, which is facilitated by a micelle-forming surfactant, cetyltrimethylammonium bromide (CTA-Br). Despite the tremendous work in recent years, the growth mechanism of Au nanorods has not been fully understood. Contrary to the widely accepted mechanism of CTA(+) micelle-templated growth of Au nanorods, we have identified the critical role of bromide ions in the seeding growth of Au nanorods. We found that even when the micelle-forming agent (CTA(+)) concentration is below its critical micelle concentration (cmc), bromide ions added in the form of NaBr can successfully effect the growth of Au nanorods in good yield. By controlling the concentration of externally added bromide ions, the rod shape and dimensions of the resulting Au nanoparticles can be readily controlled in the presence of only a minimum amount of CTABr (as a steric stabilizer for nanorods). High-resolution TEM studies show that the as-formed nanorods are perfectly single crystalline, instead of penta-twinned ones, and are bound by {111} and {100} facets with a [110] direction as the elongation direction. A mechanism is proposed to account for the seeding growth of single crystalline Au nanorods. Overall, this work explicitly demonstrates that Br(-) indeed serves as an important shape-directing agent for gold nanorod formation in the seed-mediated process. PMID:20394386

  9. Kinetics and mechanisms of the pyridinolysis of phenyl and 4-nitrophenyl chlorothionoformates. Formation and hydrolysis of 1-(aryloxythiocarbonyl)pyridinium cations.

    PubMed

    Castro, Enrique A; Cubillos, María; Santos, José G

    2004-07-01

    The title reactions are subjected to a kinetic study in water, at 25.0 degrees C, and an ionic strength of 0.2 M (KCl). By following the reactions spectrophotometrically two consecutive reactions are observed: the first is formation of the corresponding thionocarbamates (1-(aryloxythiocarbonyl)pyridinium cations) and the second is their decomposition to the corresponding phenol and pyridine, and COS. Pseudo-first-order rate coefficients (k(obsd1) and k(obsd2), respectively) are found under excess amine. Plots of k(obsd1) vs free pyridine concentration at constant pH are linear, with the slope (k(N)) independent of pH. The Brønsted-type plots (log k(N) vs pK(a) of the conjugate acids of the pyridines) are linear with slopes beta = 0.07 and 0.11 for the reactions of phenyl and 4-nitrophenyl chlorothionoformates, respectively. These Brønsted slopes are in agreement with those found in other stepwise reactions of the same pyridines in water, where the formation of a tetrahedral intermediate is the rate-determining step. In contrast to the stepwise mechanism of the title reactions that for the reactions of the same substrates with phenols is concerted, which means that substitution of a pyridino moiety in a tetrahedral intermediate by a phenoxy group destabilizes the intermediate. The second reaction corresponds to the pyridine-catalyzed hydrolysis of the corresponding 1-(aryloxythiocarbonyl)pyridinium cation. Plots of k(obsd2) vs free pyridine concentration at constant pH are linear, with the slope (k(H)) independent of pH. The Brønsted plots for k(H) are linear with slopes beta = 0.19 and 0.26 for the reactions of the phenyl and 4-nitrophenyl derivatives, respectively. These low values are explained by the fact that as pK(a) increases the effect of a better pyridine catalyst is compensated by a worse leaving pyridine from the corresponding thionocarbamate PMID:15230606

  10. Bromate formation in bromide-containing water through the cobalt-mediated activation of peroxymonosulfate.

    PubMed

    Li, Zhaobing; Chen, Zhi; Xiang, Yingying; Ling, Li; Fang, Jingyun; Shang, Chii; Dionysiou, Dionysios D

    2015-10-15

    Bromate formation in bromide-containing water through the cobalt (Co)-mediated activation of peroxymonosulfate (PMS) was investigated. Increasing the PMS dosage and the cobalt dosage increased the formation of bromate and bromate yields of up to 100% were recorded under the test conditions. The bromate yield increased to a maximum as the pH rose from 2.7 to 6 before decreasing by over 90% as the pH rose further from 6 to above 9. The bromate formation is a two-step process involving free bromine as a key intermediate and bromate as the final product. In the first step, apart from the known oxidation of bromide to free bromine and of free bromine to bromate by sulfate radicals (SO4(-)), Co(III) produced from the oxidation of Co(II) by PMS and SO4(-) also oxidizes bromide to free bromine. The contribution of Co(III) to the bromate formation was verified with the addition of methanol and EDTA, a radical scavenger and a Co(III) ligand, respectively. In the presence of methanol, free bromine formation increased with increasing Co(II) dosage but no bromate was detected, indicating that Co(III) oxidized bromide to form free bromine but not bromate. In the presence of both EDTA and methanol, no free bromine or bromate was detected, as Co(III) was stabilized by EDTA to form the Co(III)EDTA(-) complex, which could not oxidize bromide. Mathematical simulation further suggested that Co(III) outweighed SO4(-) to oxidize bromide to free bromine. On the other hand, SO4(-) is essential for the oxidation of free bromine to bromate in the second step. In real water, the presence of NOM significantly decreased the bromate formation but caused the brominated organic DBP formation with high quantity. This is the first study to demonstrate the significant bromate formation in the Co/PMS system and the substantial contribution of Co(III) to the formation. PMID:26143270

  11. Cobalt-Catalyzed Cross-Coupling of Grignards with Allylic and Vinylic Bromides: Use of Sarcosine as a Natural Ligand.

    PubMed

    Frlan, Rok; Sova, Matej; Gobec, Stanislav; Stavber, Gaj; Časar, Zdenko

    2015-08-01

    Sarcosine was discovered to be an excellent ligand for cobalt-catalyzed carbon-carbon cross-coupling of Grignard reagents with allylic and vinylic bromides. The Co(II)/sarcosine catalytic system is shown to perform efficiently when phenyl and benzyl Grignards are coupled with alkenyl bromides. Notably, previously unachievable Co-catalyzed coupling of allylic bromides with Grignards to linearly coupled α-products was also realized with Co(II)/sarcosine catalyst. This method was used for efficient preparation of the key intermediate in an alternative synthesis of the antihyperglycemic drug sitagliptin. PMID:26158563

  12. Lipophilicity indices derived from the liquid chromatographic behavior observed under bimodal retention conditions (reversed phase/hydrophilic interaction): application to a representative set of pyridinium oximes.

    PubMed

    Voicu, Victor; Sârbu, Costel; Tache, Florentin; Micăle, Florina; Rădulescu, Ştefan Flavian; Sakurada, Koichi; Ohta, Hikoto; Medvedovici, Andrei

    2014-05-01

    The liquid chromatographic behavior observed under bimodal retention conditions (reversed phase and hydrophilic interaction) offers a new basis for the determination of some derived lipophilicity indices. The experiments were carried out on a representative group (30 compounds) of pyridinium oximes, therapeutically tested in acetylcholinesterase reactivation, covering a large range of lipophilic character. The chromatographic behavior was observed on a mixed mode acting stationary phase, resulting from covalent functionalization of high purity spherical silica with long chain alkyl groups terminated by a polar environment created through the vicinal diol substitution at the lasting carbon atoms (Acclaim Mixed Mode HILIC 1 column). Elution was achieved by combining different proportions of 5 mM ammonium formiate solutions in water and acetonitrile. The derived lipophilicity indices were compared with logP values resulting from different computational algorithms. The correlations between experimental and computed data sets are significant. To obtain a better insight on the transition from reversed phase to hydrophilic interaction retention mechanisms, the variation of the thermodynamic parameters determined through the van׳t Hoff approach was also discussed. PMID:24720980

  13. Effects of pyridinium chlorochromate adulterant (urine luck) on testing for drugs of abuse and a method for quantitative detection of chromium (VI) in urine.

    PubMed

    Paul, B D; Martin, K K; Maguilo, J; Smith, M L

    2000-01-01

    Pyridinium chlorochromate (PCC) as an adulterant is popular for concealing drug-positive results. When 11-nor-delta9-THC-9-carboxylic acid (THC-acid) in urine was treated with 2 mmol/L of PCC (Cr6+ 104 microg/mL), 58-100% of the THC-acid was lost. The loss increased with decreasing pH and increasing reaction time (0-3 days). Free codeine and free morphine remained unaffected by PCC at pH within the physiological range of the urine (pH 5-7). At lower pH, the loss of free morphine varied from 0 to 100%. Amphetamine, methamphetamine, benzoylecgonine, and PCP remained unaffected by PCC when exposed to the oxidant for three days in urine pH of 3-7. Chromium (VI) from PCC in a urine solution was detected by a color reaction with 1,5-diphenylcarbazide (DPC). When the reagent was added to the urine, an immediate red-violet color appeared. The chromium-DPC complex showed a characteristic absorption peak at wavelength 544 nm with a shoulder at wavelength 575 nm. The ratio of absorption was used to identify the chromium compound. The concentration of chromium (VI) was determined by measuring absorption at wavelength 544 nm and was linear over 0.5-20 microg/mL. The limit of detection of the procedure was 0.37 microg/mL. PMID:10872568

  14. On the molecular structure and UV/vis spectroscopic properties of the solvatochromic and thermochromic pyridinium-N-phenolate betaine dye B30.

    PubMed

    Catalán, Javier; Garcia de Paz, Jose Luis; Reichardt, Christian

    2010-06-01

    Quantum chemical calculations as well as vis absorption and fluorescence measurements of the pyridinium-N-phenolate betaine dye B30, dissolved in 1-chlorobutane at temperatures between 343 and 77 K, shed more light on the solvatochromism, thermosolvatochromism, and photophysical behavior of this probe dye, formerly used to establish an empirical scale of solvent polarity, called E(T)(30) or E(T)(N) scale. A new calculated gas-phase E(T)(30) value is reported. Complementary to recent work of Kharlanov and Rettig (J. Phys. Chem. A 2009, 113, 10693-10703), it is shown that fluorescence of B30 in 1-chlorobutane solution is observable already at temperatures just below the solvent's melting point and not only at 77 K. Analogous to increasing solvent polarity, decreasing solvent temperature leads to a large hypsochromic shift of the vis absorption band of B30, dissolved in 1-chlorobutane (Deltalambda = -245 nm from 797 nm at 343 K to 552 nm at 77 K). This thermosolvatochromism can be easily seen: the solution color changes from greenish yellow (343 K) to magenta-violet (77 K). PMID:20446695

  15. Ligand-based 3D QSAR analysis of reactivation potency of mono- and bis-pyridinium aldoximes toward VX-inhibited rat acetylcholinesterase.

    PubMed

    Dolezal, Rafael; Korabecny, Jan; Malinak, David; Honegr, Jan; Musilek, Kamil; Kuca, Kamil

    2015-03-01

    To predict unknown reactivation potencies of 12 mono- and bis-pyridinium aldoximes for VX-inhibited rat acetylcholinesterase (rAChE), three-dimensional quantitative structure-activity relationship (3D QSAR) analysis has been carried out. Utilizing molecular interaction fields (MIFs) calculated by molecular mechanical (MMFF94) and quantum chemical (B3LYP/6-31G*) methods, two satisfactory ligand-based CoMFA models have been developed: 1. R(2)=0.9989, Q(LOO)(2)=0.9090, Q(LTO)(2)=0.8921, Q(LMO(20%))(2)=0.8853, R(ext)(2)=0.9259, SDEP(ext)=6.8938; 2. R(2)=0.9962, Q(LOO)(2)=0.9368, Q(LTO)(2)=0.9298, Q(LMO(20%))(2)=0.9248, R(ext)(2)=0.8905, SDEP(ext)=6.6756. High statistical significance of the 3D QSAR models has been achieved through the application of several data noise reduction techniques (i.e. smart region definition SRD, fractional factor design FFD, uninformative/iterative variable elimination UVE/IVE) on the original MIFs. Besides the ligand-based CoMFA models, an alignment molecular set constructed by flexible molecular docking has been also studied. The contour maps as well as the predicted reactivation potencies resulting from 3D QSAR analyses help better understand which structural features are associated with increased reactivation potency of studied compounds. PMID:25588616

  16. Crystal structure of bis­(1-hexyl-N,N-di­methyl­pyridinium) bis­(maleo­nitrile­dithiol­ato)nickelate(II)

    PubMed Central

    Yu, Shan-Shan; Zhang, Hui

    2016-01-01

    The asymmetric unit of the title compound, (C13H23N2)2[Ni(C4N2S2)2], consists of a 1-hexyl-N,N-di­methyl­pyridinium cation and one half of a [Ni(mnt)2]2− dianion (mnt2− = maleo­nitrile­dithiol­ate) in which the Ni2+ cation lies on a crystallographic inversion centre. The square-planar coordination about Ni2+ comprises four S atoms from two bidentate chelate mnt2− ligands [Ni—S = 2.1791 (9) and 2.1810 (8) Å, and S—Ni—S bite angle = 91.93 (3)°]. The hydro­carbon chains of cations show trans-planar conformations and lie approximately parallel to the long mol­ecular axis of the [Ni(mnt)2]2− anions, giving stacks along the c axis. The anions and cations form layers lying parallel to the bc plane. Only weak C—H⋯Ni and C—H⋯π associations are present in the crystal packing. PMID:27536413

  17. Amination of the pyridinium cations in betaines. Synthesis of substituted pyrimido(5,6-c)-1'-azaquinolizine and its dihydro analogs

    SciTech Connect

    Kochkanyan, R.O.; Lukanyuk, S.S.

    1987-11-01

    The pyridinium cations within betaines can be aminated under mild conditions with aqueous ammonia, ultimately undergoing cyclization to a new tricyclic system: 4-substituted-3,5-dioxopyrimido(5,6-c)-1'-azaquinolizine. Intermediates in the reaction are 4-substituted-3,5-dioxo-2,2-dihydropyrimido(5,6-c)-6H-1'-quinolizines. Formation of the methylene group is coupled with transfer of an atom of hydrogen or deuterium from the ..cap alpha..-carbon of the dihydropyridine in compound II to the carbon atom of the azomethine group. The NMR spectrum is represented by the methylene proton signal (3.96 ppm) and by the multiplets of the pyridine and phenyl protons centered at 7.63 and 6.38 ppm respectively. Upon chloranil oxidation, and upfield shift of the pyridine protons is observed: the ..cap alpha..-proton forms a doublet (10.05 ppm, J= 6 Hz), the ..beta..-protons form a doublet and a triplet with centers at 8.57 (J = 8 Hz) and 8.22 (J = 7 Hz) ppm respectively, and the ..gamma..-proton forms a triplet at 8.8 (J = 7 Hz) ppm.

  18. Study by Raman spectroscopy of the adsorption of Ru-bi and ter pyridinium complexes on nanocrystalline TiO{sub 2} during photoelectrochemical experiments

    SciTech Connect

    Hugot-Le Goff, A.; Joiret, S.; Falaras, P.; Graetzel, M.; Pechy, P.; Vlakopoulos, N.; Zakeeruddin, M.

    1995-12-31

    The adsorption on a titanium dioxide substrate of organic monolayers used in the nanocrystalline dye sensitized solar cells was investigated by Raman Spectroscopy, owing to the high resonance effect in these molecules. During the polarization of TiO{sub 2} modified by Ru-bi or ter pyridinium compounds in a photoelectrochemical cell, an enhancement effect appeared, allowing to scrutinize the part of the complex which is in contact with the substrate. This effect remains in a large extend unexplained; it could be assimilated to SERRS (Surface Enhanced Raman Resonant). Noticeable differences appeared in function of the nature of the pyridil ligands. In the case of bipy, in addition to the ``normal`` (ground state) Raman bands, a new series of bands appeared which correspond to the particular ligand exchanging electrons with the substrate titanium atoms. The Raman intensity of these new peaks is directly related to the electric field (i.e., to the potential magnitude independently of its cathodic or anodic nature). In the case of terpy, the enhancement mechanism seems different. The similarity of the molecular configuration created by the adsorption with the radical anion formed by the excitation of the metal ligand charge transfer complex has to be emphasized. Very interesting prospects for the understanding of the adsorption mechanisms are therefore opened.

  19. Reactivity of anthracene in liquid SbCl/sub 3/-AlCl/sub 3/-N-(1-BUTYL)pyridinium chloride mixtures

    SciTech Connect

    Zingg, S.P.; Buchanan, A.C.; Chapman, D.M.; Dworkin, A.S.; Smith, G.P.; Sorlie, M.

    1983-05-01

    Mixtures of SbCl/sub 3/ and N-(1-butyl)pyridinium chloride (BPCl) containing 75-87 mol % SbCl/sub 3/ and SbCl/sub 3/-AlCl/sub 3/-BPCl mixtures containing 60 mol % SbCl/sub 3/ and 17-24 mol % BPCl were found to be liquid at 25/sup 0/C. Dilute solutions of anthracene were stable in ternary mixtures containing 18 mol % AlCl/sub 3/, but in mixtures containing 22-24 mol % AlCl/sub 3/, anthracene reacted under the influence of the solvent, which behaved as both oxidant and H-transfer catalyst. The oxidized product was protonated anthracene, which was stable in this melt. The source of protons was provided by hydrogen-liberating Scholl condensations combined with the reduction of Sb(III). A part of the hydrogen from Scholl reactions reacted with anthracene to form 9,10-dihydroanthracene. By contrast, a liquid mixture without SbCl/sub 3/, AlCl/sub 3/-BPCl (2:1 mole ratio), proved to be a much less active H-transfer catalyst than the SbCl/sub 3/-rich liquids even though it is a stronger Lewis acid, and it did not induce protonation beyond a trace attributable to protic impurities.

  20. Comparative studies of the release of 1-methyl-4-phenyl-pyridinium species (MPP/sup +/) from rat and mouse brain synaptosomes

    SciTech Connect

    Abell, C.W.; Shen, R.S.; Gessner, W.; Brossi, A.

    1986-05-01

    The parkinsonian producing neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), selectively destroys nigrostriatal neurons in humans and primates and depletes striatal dopamine in mice but not in rats. MPTP is oxidized by monoamine oxidase B (MAO B) in glial cells and/or serotonergic neurons to form a 1-methyl-4-phenyl pyridinium species (MPP/sup +/), which accumulates in dopaminergic neurons in the substantia nigra and is thought to cause cell destruction. The authors compared the spontaneous release of MPP/sup +/ in striatal and hypothalamic synaptosomes prepared from male Sprague-Dawley rats and male C57BL mice. Synaptosomes were preloaded with (/sup 3/H)-MPP/sup +/ (final concentration of 0.8 ..mu..M, 265 ..mu..Ci/..mu..mol) in physiological Tris containing 0.02% ascorbic acid for 7.5 min at 37/sup 0/C. Hypothalamic, but not striatal, (/sup 3/H)-MPP/sup +/ release from rat and mouse brain was directly proportional to its initial loading concentration (0.008-0.8 ..mu..M). Striatal synaptosomes from rats and mice gave identical rates of spontaneous release of (/sup 3/H)- MPP/sup +/, but the rate of release of hypothalamus is 60% faster in rats than in mice. (/sup 3/H)-MPP/sup +/ release from rat and mouse striatum, but not hypothalamus, was stimulated by monoamines and MAO substrates and inhibitors, a finding that suggests a role for MAO in the intraneuronal transport of MPP/sup +/.

  1. Crystal structure of tris-[4-(di-methyl-amino)-pyridinium] tris-(oxalato-κ(2) O,O')chromate(III) tetra-hydrate.

    PubMed

    Makon Ma Houga, Noé; Capet, Frédéric; Nenwa, Justin; Bebga, Gouet; Foulon, Michel

    2015-11-01

    In the title hybrid salt, (C7H11N2)3[Cr(C2O4)3]·4H2O, the central Cr(III) ion of the complex anion (point group symmetry 2) is coordinated by six O atoms from three chelating oxalate(2-) ligands in a slightly distorted octa-hedral coordination sphere. The Cr-O bond lengths vary from 1.9577 (11) to 1.9804 (11) Å, while the chelate O-Cr-O angles range from 82.11 (6) to 93.41 (5)°. The 4-(di-methyl-amino)-pyridinium cations (one situated in a general position and one on a twofold rotation axis) are protonated at the pyridine N atoms. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the cations and anions into a three-dimensional network. π-π inter-actions between the pyridine rings of adjacent cations provide additional stabilization of the crystal packing, with the closest centroid-to-centroid distances being 3.541 (1) and 3.575 (1) Å. PMID:26594521

  2. Tandem β-elimination/hetero-michael addition rearrangement of an N-alkylated pyridinium oxime to an O-alkylated pyridine oxime ether: an experimental and computational study.

    PubMed

    Picek, Igor; Vianello, Robert; Šket, Primož; Plavec, Janez; Foretić, Blaženka

    2015-02-20

    A novel OH(-)-promoted tandem reaction involving C(β)-N(+)(pyridinium) cleavage and ether C(β)-O(oxime) bond formation in aqueous media has been presented. The study fully elucidates the fascinating reaction behavior of N-benzoylethylpyridinium-4-oxime chloride in aqueous media under mild reaction conditions. The reaction journey begins with the exclusive β-elimination and formation of pyridine-4-oxime and phenyl vinyl ketone and ends with the formation of O-alkylated pyridine oxime ether. A combination of experimental and computational studies enabled the introduction of a new type of rearrangement process that involves a unique tandem reaction sequence. We showed that (E)-O-benzoylethylpyridine-4-oxime is formed in aqueous solution by a base-induced tandem β-elimination/hetero-Michael addition rearrangement of (E)-N-benzoylethylpyridinium-4-oximate, the novel synthetic route to this engaging target class of compounds. The complete mechanistic picture of this rearrangement process was presented and discussed in terms of the E1cb reaction scheme within the rate-limiting β-elimination step. PMID:25562471

  3. Growth and characterization of an organic single crystal: 2-[2-(4-diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide.

    PubMed

    Senthil, K; Kalainathan, S; Ruban Kumar, A

    2014-05-01

    Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. (1)H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker's hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal. PMID:24566112

  4. Cation dynamics in the pyridinium based ionic liquid 1-N-butylpyridinium bis((trifluoromethyl)sulfonyl) as seen by quasielastic neutron scattering.

    PubMed

    Embs, Jan P; Burankova, Tatsiana; Reichert, Elena; Hempelmann, Rolf

    2012-11-01

    Quasielastic neutron scattering (QENS) has been used to study the cation dynamics in the pyridinium based ionic liquid (IL) 1-N-butylpyridinium bis((trifluoromethyl)sulfonyl)imide (BuPy-Tf(2)N). This IL allows for a detailed investigation of the dynamics of the cations only, due to the huge incoherent scattering cross section of the cation (σ(inc)(cation) > σ(inc)(anion)). The measured spectra can be decomposed into two Lorentzian lines, indicative of two distinct dynamic processes. The slower of these two processes is diffusive in nature, whereas the faster one can be attributed to localized motions. The temperature dependence of the diffusion coefficient of the slow process follows an Arrhenius law, with an activation energy of E(A) = 14.8 ± 0.3 kJ/mol. Furthermore, we present here results from experiments with polarized neutrons. These experiments clearly show that the slower of the two observed processes is coherent, while the faster one is incoherent in nature. PMID:23020511

  5. Hydrogen bonding interactions between a representative pyridinium-based ionic liquid [BuPy][BF4] and water/dimethyl sulfoxide.

    PubMed

    Wang, Nan-Nan; Zhang, Qing-Guo; Wu, Fu-Gen; Li, Qing-Zhong; Yu, Zhi-Wu

    2010-07-01

    Infrared spectroscopy and density functional theory calculations have been applied to elucidate the hydrogen bonding interactions between water/dimethyl sulfoxide (DMSO) and a representative pyridinium-based ionic liquid, 1-butylpyridinium tetrafluoroborate ([BuPy][BF(4)]). It has been found that both solvents can interact with the BuPy(+) cation through the aromatic C-H. The strength of the H-bonds involving the aromatic C-H in water is similar to that in pure [BuPy][BF(4)], but is much stronger in DMSO. For DMSO, when it forms H-bonds with the BuPy(+) cation through its S=O group, its back-side methyl groups act as electron donors, while the butyl group of the cation acts as an electron acceptor. For water, when it forms the strong anion-HOH-anion complex, it can also form H-bonds with the aromatic C-H on the BuPy(+) cation. This is different from the imidazolium-based ionic liquid, where the strong anion-cation interaction and steric hindrance from the alkyls prevent water molecules from H-bonding with the aromatic C-H other than with the anion. PMID:20550148

  6. Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-(3-hydroxypropyl)pyridinium trifluorotris(perfluoroethyl)phosphate.

    PubMed

    Marciniak, Andrzej; Wlazło, Michał

    2010-05-27

    The activity coefficients at infinite dilution, gamma(13)(infinity), for 37 solutes, alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, and water, in the ionic liquid 1-(3-hydroxypropyl)pyridinium trifluorotris(perfluoroethyl)phosphate [N-C(3)OHPY][FAP] were determined by gas-liquid chromatography at the temperatures from 308.15 to 358.15 K. The partial molar excess enthalpies at infinite dilution values DeltaH(1)(E,infinity) were calculated from the experimental gamma(13)(infinity) values obtained over the temperature range. The selectivities for aliphatics/aromatics hydrocarbons separation problem were calculated from the gamma(13)(infinity) values and compared to the literature values for other ionic liquids, N-methylpyrrolidone (NMP) and sulfolane. It was found that the investigated [N-C(3)OHPY][FAP] ionic liquid shows much higher selectivity and capacity at infinite dilution than the generally used organic solvents such as NMP, sulfolane, and other ionic liquids. PMID:20429540

  7. States and migration of an excess electron in a pyridinium-based, room-temperature ionic liquid: an ab initio molecular dynamics simulation exploration.

    PubMed

    Wang, Zhiping; Zhang, Liang; Cukier, Robert I; Bu, Yuxiang

    2010-02-28

    The structural and electronic properties of an excess electron (EE) in the ionic liquid (IL) 1-methylpyridinium chloride were explored using ab initio molecular dynamics simulations and quantum chemical calculations to give an overall understanding of the solvation and transport behavior of an EE in this IL. The results show that the EE resides in cation pi*-type orbitals and that the electronic states can be characterized by the alternating appearance of localized and delocalized states during the time evolution. The characters of the EE electronic states are determined by the number of cations contributing to the LUMO of the IL. In a localized state one or two cations contribute to the LUMO of the bulk ionic liquid, while in the delocalized state the IL LUMO is composed of pi*-type orbitals spanning nearly all the cations in the cell. The arrangement and fluctuation-induced changes of the orbital components in the empty band produce an alternation of different states and leads to the migration of the excess electron. These findings can be attributed to the special features of the electronic structures and geometries of the IL, and they can be used to explain similarities and differences between pyridinium-based and imidazolium-based ILs in mediating electron migration. PMID:20145852

  8. Reactivity of anthracene in liquid SbCl/sub 3/-AlCl/sub 3/-N-(1-butyl)pyridinium chloride mixtures

    SciTech Connect

    Zingg, S.P.; Dworkin, A.S.; Sorlie, M.; Chapman, D.M.; Buchanan, A.C. III; Smith, G.P.

    1983-01-01

    Mixtures of SbCl/sub 3/ and N-(1-butyl)pyridinium chloride (BPCl) containing 75 to 87 mol % SbCl/sub 3/ and SbCl/sub 3/-AlCl/sub 3/-BPCl mixtures containing 60 mol % SbCl/sub 3/ and 17 to 24 mol % BPCl were found to be liquid at 25/sup 0/C. Dilute solutions of anthracene were stable in ternary mixtures containing 18 mol % AlCl/sub 3/, but in mixtures containing 22 to 24 mol % AlCl/sub 3/, anthracene reacted under the influence of the solvent, which behaved as both oxidant and H-transfer catalyst. The oxidized product was protonated anthracene, which was stable in this melt. The source of protons was provided by hydrogen-liberating Scholl condensations combined with the reduction of Sb(III). A part of the hydrogen from Scholl reactions reacted with anthracene to form 9,10-dihydroanthracene. By contrast, a liquid mixture without SbCl/sub 3/, AlCl/sub 3/-BPCl (2:1 mole ratio), proved to be a much less active H-transfer catalyst than the SbCl/sub 3/-rich liquids even though it is a stronger Lewis acid, and it did not induce protonation beyond a trace attributable to protic impurities.

  9. Reactivity of anthracene in liquid SbCl/sub 3/-AlCl/sub 3/-N-(1-Butyl)Pyridinium chlrodie mixtures

    SciTech Connect

    Zingg, S.P.; Dworkin, A.S.; Soerlie, M.; Chapman, D.M.; Buchanan, A.C. III; Smith, G.P.

    1984-07-01

    Mixtures of SbCl/sub 3/ and N-(1-butyl)pyridinium chloride (BPCl) containing 75-87 mole % SbCl/sub 3/ and SbCl/sub 3/-AlCl/sub 3/-BPCl mixtures containing 60 mole % of SbCl/sub 3/ and 16-23 mole % of AlCl/sub 3/ were found to be liquid at 25/sup 0/C. Results of studies to determine to what extent SbCl/sub 3/ diluted by 25 mole % BPAlCl/sub 4/ at ambient temperature retains the catalytic properties that SbCl/sub 3/ displays at elevated temperatures for a variety of hydrogen redistribution reactions are reported. Anthracene was chosen as the hydrogen-transfer substrate, because of the extensive research on its reactivity in SbCl/sub 3/-rich high-melting mixtures. Fundamental differences in the two systems due to the fact that in the SbCl/sub 3/-rich melts, SbCl/sub 2//sup +/ is the Lewis acid and has an additional redox functionality, whereas, in the chloroaluminate melt, this acidity resides in Al/sub 2/Cl/sub 7//sup -/, which has no redox functionality are related to the catalytic activity. The role of impurities in these mixtures was investigated with results that are relevant to earlier investigations of liquid AlCl/sub 3/-BPCl mixtures. An improved procedure for purifying BPCl is described.

  10. Growth and characterization of an organic single crystal: 2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide

    NASA Astrophysics Data System (ADS)

    Senthil, K.; Kalainathan, S.; Ruban Kumar, A.

    Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. 1H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker’s hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal.

  11. Bis-pyridinium dibromides modified organo-bentonite for the removal of aniline from wastewater: A positive role of π-π polar interaction

    NASA Astrophysics Data System (ADS)

    Gu, Zheng; Gao, Manglai; Luo, Zhongxin; Lu, Laifu; Ye, Yage; Liu, Yuening

    2014-01-01

    Aniline removal is of great importance for water treatment, and adsorption is an efficient treatment method. Hexamethylene bis-pyridinium dibromide modified bentonite (HEMBP-B) was firstly prepared and characterized by XRD, FT-IR, BET, SEM, TEM and TG-DTG analysis. Adsorptive experiments of aniline on the organo-bentonite were carried out using batch method as a function of the length of linking carbon chain (n), concentration of HEMBP (C), contact time (t), temperature (T) and pH. The optimal conditions for aniline removal on HEMBP-B were as follows: n of 5 or 6, C of 1.0 CEC, t of 120 min, T of 298 K, and natural pH of 6.6. The π-π polar interaction existed between the aromatic rings of aniline and HEMBP has successfully explained the main adsorption mechanism. The equilibrium data of aniline removal on HEMBP-B followed Freundlich and D-R isothermal models precisely, which indicated a less favorable and physical process of aniline adsorption. The kinetic data could be best described by the pseudo-second-order model. Besides, the thermodynamic study revealed that aniline adsorption on HEMBP-B was non-spontaneous, exothermic and physical.

  12. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.

  13. Intermolecular Photocatalyzed Heck-like Coupling of Unactivated Alkyl Bromides by a Dinuclear Gold Complex.

    PubMed

    Xie, Jin; Li, Jian; Weingand, Vanessa; Rudolph, Matthias; Hashmi, A Stephen K

    2016-08-26

    A practical protocol for a photocatalyzed alkyl-Heck-like reaction of unactivated alkyl bromides and different alkenes promoted by dinuclear gold photoredox catalysis in the presence of an inorganic base is reported. Primary, secondary, and tertiary unactivated alkyl bromides with β-hydrogen can be applied. Esters, aldehydes, ketones, nitriles, alcohols, heterocycles, alkynes, alkenes, ethers, and halogen moieties are all well tolerated. In addition to 1,1-diarylalkenes, silylenolethers and enamides can also be applied, which further increases the synthetic potential of the reaction. The mild reaction conditions, broad substrate scope, and an excellent functional-group tolerance deliver an ideal tool for synthetic chemists that can even be used for challenging late-stage modifications of complex natural products. PMID:27348503

  14. Study of the corrosion resistance of metals in a lithium bromide solution

    SciTech Connect

    Mel'nik, V.V.; Spivak, R.Sh.; Sokolov, V.V.; Trofimenko, A.G.

    1988-07-01

    Results are reported of a study of the corrosion resistance of the stainless steels 12Kh19N10T, 10Kh17N13M3T, 08Kh17N15M3T, 10Kh21N6M2T, and 06KhI28MDT, cupronickel MNZhMts 30-1-1, nickel NP-2, and titanium alloys VT1-0, PT-1M, and PT-3V in a solution of lithium bromide for purposes of assessing these alloys for use in absorption-type refrigerating units using the bromide as an absorbent. The uniform corrosion rate was determined from the weight loss; the nonuniform corrosion rate was determined by measuring the maximum depth of the pits under a microscope. Results are comparatively evaluated.

  15. Cooperative dual palladium/silver catalyst for direct difluoromethylation of aryl bromides and iodides.

    PubMed

    Gu, Yang; Leng, Xuebing; Shen, Qilong

    2014-01-01

    Difluoromethylated arenes are one of the privileged structural motifs that are important for fine tuning the biological properties of drug molecules. No general catalytic method exists for the formation of difluoromethylarenes. Previous methods for the preparation of difluoromethylarenes typically required harsh conditions, multiple steps or stoichiometric amount of catalysts. Here we report a cooperative dual palladium/silver catalyst system for direct difluoromethylation of aryl bromides and iodides under mild conditions. We develop the system by initial preparation of the putative intermediates in the dual-catalytic cycles, followed by studying the elemental steps to demonstrate the viability of the proposed cooperative catalytic cycle. The reaction is compatible with a variety of functional groups such as ester, amide, protected phenoxide, protected ketone, cyclopropyl, bromide and heteroaryl subunits such as pyrrole, benzothiazole, carbazole or pyridine. PMID:25377759

  16. Underpotential deposition of Cu on Pt(001): Interface structure and the influence of adsorbed bromide

    NASA Astrophysics Data System (ADS)

    Lucas, C. A.; Markovic, N. M.; Ross, P. N.

    1998-05-01

    Using in situ x-ray diffraction, we studied the underpotential deposition (UPD) of copper onto a Pt(001) electrode both in pure perchloric acid and in the presence of bromide anions. In pure perchloric acid, the Cu is deposited in pseudomorphic p(1×1) islands. In the presence of bromide anions, the strong Pt-Br interaction significantly broadens the potential range of Cu UPD. We propose that Br remains in the interface region throughout the UPD process, at first in a disordered Cu-Br phase and then, at more negative potential, forming a c(2×2) closed-packed monolayer on top of the completed p(1×1) Cu monolayer. The structures are compared to those found during Cu UPD onto Pt(111), and explained in terms of the metal-halide interactions and the Pt surface atomic geometry.

  17. A neutron scattering and modelling study of aqueous solutions of tetramethylammonium and tetrapropylammonium bromide.

    PubMed

    Nilsson, Emelie J; Alfredsson, Viveka; Bowron, Daniel T; Edler, Karen J

    2016-04-20

    We have investigated the properties in water of two tetraalkylammonium bromides (tetramethylammonium, TMA(+), and tetrapropylammonium, TPA(+)), at 0.4 M, using neutron scattering coupled with empirical potential structure refinement to arrive at an atomistic description. Having both a polar and an apolar moiety, it is of interest to determine the strength of each moiety as a function of the alkyl chain length. TMA(+) and TPA(+), having different impact as structure directors in zeolite synthesis, were chosen for this study. Water arranges tetrahedrally around TMA(+) and in an almost featureless manner around TPA(+). TMA(+) and TPA(+) show an apolar hydration with TPA(+) being slightly more apolar. TPA(+) has a tendency to form small clusters of 2-4 molecules and to fold into a compact configuration. Both molecules correlate similarly with the bromide ion but do not dissociate completely at this concentration. PMID:27051995

  18. Ultrasound-assisted coating of polyester fiber with silver bromide nanoparticles.

    PubMed

    Moosavi, Raziyeh; Abbasi, Amir Reza; Yousefi, Mohammad; Ramazani, Ali; Morsali, Ali

    2012-11-01

    The growth of silver bromide nanoparticles on polyester fiber was achieved by sequential dipping steps in alternating bath of potassium bromide and silver nitrate under ultrasound irradiation. The effects of ultrasound irradiation, concentration and sequential dipping steps in growth of the AgBr nanoparticles have been studied. Particle sizes and morphology of nanoparticle are depending on power of ultrasound irradiation, sequential dipping steps and concentration. These systems depicted a decrease in the particles size accompanying an increase in the sonication power. Results suggest that an increasing of sequential dipping steps and concentration led to an increasing of particle size. The physicochemical properties of the nanoparticles were determined by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). PMID:22494594

  19. Visible Light-Induced Photoredox Construction of Trifluoromethylated Quaternary Carbon Centers from Trifluoromethylated Tertiary Bromides.

    PubMed

    Huan, Feng; Chen, Qing-Yun; Guo, Yong

    2016-08-19

    A mild, operationally simple, visible light-induced photoredox method for constructing novel trifluoromethylated quaternary carbon centers from trifluoromethylated tertiary bromides has been developed. Using this method, a wide range of alkenes were successfully bifunctionalized to γ-butyrolactams. As for electron-rich alkenes, reactions catalyzed by Ir(dF(CF3)ppy)2(dtbbpy)(PF6) were kinetic processes with high yields and short times. For styrenes, reactions catalyzed by Ir(ppy)2(dtbbpy)(PF6) were thermodynamic processes with moderate yields and prolonged reaction times. For aliphatic alkenes, the reactions were neither thermodynamic nor kinetic and fac-Ir(ppy)3 was used as catalyst. Thus, reactions were not as efficient as electron-rich alkenes. The atom-transfer radical addition reactions of trifluoromethylated tertiary bromides with alkynes were also achieved. The configuration of products we separated was E type only. Some of the products exhibited bactericidal activity. PMID:27438228

  20. Preparation and optical characteristics of layered perovskite-type lead-bromide-incorporated azobenzene chromophores

    NASA Astrophysics Data System (ADS)

    Sasai, Ryo; Shinomura, Hisashi

    2013-02-01

    Lead bromide-based layered perovskite powders with azobenzene derivatives were prepared by a homogeneous precipitation method. From the diffuse reflectance (DR) and photoluminescence (PL) spectra of the hybrid powder materials, the present hybrids exhibited sharp absorption and PL peaks originating from excitons produced in the PbBr42- layer. When the present hybrid powder was irradiated with UV light at 350 nm, the absorption band from the trans-azobenzene chromophore, observed around 350 nm, decreased, while the absorption band from the cis-azobenzene chromophore, observed around 450 nm, increased. These results indicate that azobenzene chromophores in the present hybrid materials exhibit reversible photoisomerization. Moreover, it was found that the PL intensity from the exciton also varied due to photoisomerization of the azobenzene chromophores in the present hybrid. Thus, for the first time we succeeded in preparing the azobenzene derivative lead-bromide-based layered perovskite with photochromism before and after UV light irradiation.