Sample records for h3o h2do hd2o

  1. On the existence of the hypervalent H3O, H2DO, HD2O, and D3O radicals

    Hvelplunda, P.; Nielsen, S.B.; Panjaa, S.;


    The existence of oxonium radicals on the microsecond time scale has been up for much debate, and strong isotope effects have been reported. Here we show that H3O, H2DO, HD2O, and D3O all have subnanosecond lifetimes when they are formed in charge-transfer collisions between oxonium cations...... and cesium. A kinetic isotope effect on hydrogen versus deuterium loss from HD2O was found to be 2.4, similar to that found in dissociative recombination of HD2O+ and for dissociation after electron transfer to HD2O+ from potassium....

  2. Detection of extragalactic H3O+

    van der Tak, F. F. S.; Aalto, S.; Meijerink, R.


    Context. The H3O+ molecule probes the oxygen chemistry and the ionization rate of dense circumnuclear gas in galaxies. Aims. Recent H3O+ observations show variations in the cosmic-ray ionization rate, by factors of >10 within our Galaxy. Methods. Using the JCMT, we have observed the 364 GHz line of

  3. Radiative cooling of H3O+ and its deuterated isotopologues

    Melnikov, Vladlen V; Tennyson, Jonathan; Jensen, Per


    In conjunction with ab initio potential energy and dipole moment surfaces for the electronic ground state, we have made a theoretical study of the radiative lifetimes for the hydronium ion H$_3$O$^{+}$ and its deuterated isotopologues. We compute the ro-vibrational energy levels and their associated wavefunctions together with Einstein coefficients for the electric dipole transitions. A detailed analysis of the stability of the ro-vibrational states have been carried out and the longest-living states of the hydronium ions have been identified. We report estimated radiative lifetimes and cooling functions for temperatures $<$ 200 K. A number of long-living meta-stable states are identified, capable of population trapping.

  4. H3O+ tetrahedron induction in large negative linear compressibility

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan


    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)∙2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O+ tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials. PMID:27184726

  5. H3O(+) tetrahedron induction in large negative linear compressibility.

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan


    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)∙2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O(+) tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials.

  6. Experimental and Theoretical Kinetics for the H2O H2/D2 H3O /H2DO H/DReactions: Observation of the Rotational Effect in the Temperature Dependence (Postprint)


    the water molecular ion and molecular hydrogen is a key step in the formation of hydroxyl radical and water molecules in the interstellar medium.1−3...L min−1) and temperature. After traveling the length of the flow tube, the core of the flow is sampled through a truncated nosecone with a 2 mm...Cheuk Ng for numerous stimulating discussions. ■ REFERENCES (1) Herbst, E.; Klemperer, W. Formation and Depletion of Molecules in Dense Interstellar

  7. Product spin-orbit state resolved dynamics of the H+H2O and H+D2O abstraction reactions.

    Brouard, M; Burak, I; Marinakis, S; Rubio Lago, L; Tampkins, P; Vallance, C


    The product state-resolved dynamics of the reactions H+H(2)O/D(2)O-->OH/OD((2)Pi(Omega);v',N',f )+H(2)/HD have been explored at center-of-mass collision energies around 1.2, 1.4, and 2.5 eV. The experiments employ pulsed laser photolysis coupled with polarized Doppler-resolved laser induced fluorescence detection of the OH/OD radical products. The populations in the OH spin-orbit states at a collision energy of 1.2 eV have been determined for the H+H(2)O reaction, and for low rotational levels they are shown to deviate from the statistical limit. For the H+D(2)O reaction at the highest collision energy studied the OD((2)Pi(3/2),v'=0,N'=1,A') angular distributions show scattering over a wide range of angles with a preference towards the forward direction. The kinetic energy release distributions obtained at 2.5 eV also indicate that the HD coproducts are born with significantly more internal excitation than at 1.4 eV. The OD((2)Pi(3/2),v'=0,N'=1,A') angular and kinetic energy release distributions are almost identical to those of their spin-orbit excited OD((2)Pi(1/2),v'=0,N'=1,A') counterpart. The data are compared with previous experimental measurements at similar collision energies, and with the results of previously published quasiclassical trajectory and quantum mechanical calculations employing the most recently developed potential energy surface. Product OH/OD spin-orbit effects in the reaction are discussed with reference to simple models.

  8. Crown Ether Complexes with H3O+ and NH4+: Proton Localization and Proton Bridge Formation

    Hurtado, P.; Gamez, F.; Hamad, S.; Martinez-Haya, B.; Steill, J. D.; Oomens, J.


    The complexes formed by crown ethers with hydronium and ammonium cations are of key relevance for the understanding of their supramolecular behavior in protic solvents. In this work, the complexes of the 15-crown-5 (15c5) and 18-crown-6 (18c6) ethers with H3O+ and NH4+ and their deuterated variants

  9. Excited OH+, H2O+, and H3O+ in NGC 4418 and Arp 220

    González-Alfonso, E; Bruderer, S; Müller, H S P; Graciá-Carpio, J; Sturm, E; Lutz, D; Poglitsch, A; Feuchtgruber, H; Veilleux, S; Contursi, A; Sternberg, A; Hailey-Dunsheath, S; Verma, A; Christopher, N; Davies, R; Genzel, R; Tacconi, L


    We report on Herschel/PACS observations of absorption lines of OH+, H2O+ and H3O+ in NGC 4418 and Arp 220. Excited lines of OH+ and H2O+ with E_lower of at least 285 and \\sim200 K, respectively, are detected in both sources, indicating radiative pumping and location in the high radiation density environment of the nuclear regions. Abundance ratios OH+/H2O+ of 1-2.5 are estimated in the nuclei of both sources. The inferred OH+ column and abundance relative to H nuclei are (0.5-1)x10^{16} cm-2 and \\sim2x10^{-8}, respectively. Additionally, in Arp 220, an extended low excitation component around the nuclear region is found to have OH+/H2O+\\sim5-10. H3O+ is detected in both sources with N(H3O+)\\sim(0.5-2)x10^{16} cm-2, and in Arp 220 the pure inversion, metastable lines indicate a high rotational temperature of ~500 K, indicative of formation pumping and/or hot gas. Simple chemical models favor an ionization sequence dominated by H+ - O+ - OH+ - H2O+ - H3O+, and we also argue that the H+ production is most likely...

  10. Evidence of the Key Role of H3O(+) in Phospholipid Membrane Morphology.

    Cranfield, Charles G; Berry, Thomas; Holt, Stephen A; Hossain, Khondker R; Le Brun, Anton P; Carne, Sonia; Al Khamici, Heba; Coster, Hans; Valenzuela, Stella M; Cornell, Bruce


    This study explains the importance of the phosphate moiety and H3O(+) in controlling the ionic flux through phospholipid membranes. We show that despite an increase in the H3O(+) concentration when the pH is decreased, the level of ionic conduction through phospholipid bilayers is reduced. By modifying the lipid structure, we show the dominant determinant of membrane conduction is the hydrogen bonding between the phosphate oxygens on adjacent phospholipids. The modulation of conduction with pH is proposed to arise from the varying H3O(+) concentrations altering the molecular area per lipid and modifying the geometry of conductive defects already present in the membrane. Given the geometrical constraints that control the lipid phase structure of membranes, these area changes predict that organisms evolving in environments with different pHs will select for different phospholipid chain lengths, as is found for organisms near highly acidic volcanic vents (short chains) or in highly alkaline salt lakes (long chains). The stabilizing effect of the hydration shells around phosphate groups also accounts for the prevalence of phospholipids across biology. Measurement of ion permeation through lipid bilayers was made tractable using sparsely tethered bilayer lipid membranes with swept frequency electrical impedance spectroscopy and ramped dc amperometry. Additional evidence of the effect of a change in pH on lipid packing density is obtained from neutron reflectometry data of tethered membranes containing perdeuterated lipids.

  11. Formation of H3O+ from alcohols and ethers induced by intense laser fields.

    Shirota, Tatsuro; Mano, Narutoshi; Tsuge, Masashi; Hoshina, Kennosuke


    The processes of H(3)O(+) production from alcohols (ethanol, 2-propanol, 1-propanol, 2-butanol) and ethers (diethyl ether and ethyl methyl ether), and their deuterium-substituted species, by intense laser fields (800 nm, 100 fs, approximately 1 x 10(14) W/cm) were investigated through time-of-flight (TOF) mass spectrometry. H(3)O(+) formation was observed for all these compounds except for ethyl methyl ether. From the analysis of TOF signals of H((3-n))D(n)O(+) (n = 0, 1, 2, and 3) that have expanding tails with increasing flight time, it has been confirmed that the reaction proceeds through metastable dissociation from the intermediate species C(2)H((5-m))D(m)O(+)(m = 0-5). The common shape of the H((3-n))D(n)O(+) signal profiles contains two major distributions in the time constant, i.e., fast and slow components of production. Ab initio calculations for the isomers and transition states of C(2)H(5)O(+) were also performed, and the observed H((3-n))D(n)O(+) production mechanism has been discussed. In addition, a stable isomer having a complex structure and two isomerization pathways were discovered to contribute to the H(3)O(+) formation process.

  12. Dihydronium tetrachromate(VI, (H3O2Cr4O13

    Vladislav Kulikov


    Full Text Available The crystal structure of (H3O2Cr4O13 is isotypic with K2Cr4O13. The finite tetrachromate anion in the title structure consists of four vertex-sharing CrO4 tetrahedra and exhibits a typical zigzag arrangement. The crystal packing is stabilized by hydrogen bonds between these anions and hydronium cations. The two different hydronium cations are surrounded by nine O atoms of tetrachromate anions, with O...O distances ranging between 2.866 (8 and 3.282 (7 Å.

  13. Ultrafast Scavenging of the Precursor of H(•) Atom, (e(-), H3O(+)), in Aqueous Solutions.

    Balcerzyk, Anna; Schmidhammer, Uli; Wang, Furong; de la Lande, Aurélien; Mostafavi, Mehran


    Picosecond pulse radiolysis measurements have been performed in several highly concentrated HClO4 and H3PO4 aqueous solutions containing silver ions at different concentrations. Silver ion reduction is used to unravel the ultrafast reduction reactions observed at the end of a 7 ps electron pulse. Solvated electrons and silver atoms are observed by the pulse (electron beam)-probe (supercontinuum light) method. In highly acidic solutions, ultrafast reduction of silver ions is observed, a finding that is not compatible with a reaction between the H(•) atom and silver ions, which is known to be thermally activated. In addition, silver ion reduction is found to be even more efficient in phosphoric acid solution than that in neutral solution. In the acidic solutions investigated here, the species responsible for the reduction of silver atoms is considered to be the precursor of the H(•) atom. This precursor, denoted (e(-), H3O(+)), is a pair constituting an electron (not fully solvated) and H3O(+). Its structure differs from that of the pair of a solvated electron and a hydronium ion (es(-), H3O(+)), which absorbs in the visible region. The (e(-), H3O(+)) pair , called the pre-H(•) atom here, undergoes ultrafast electron transfer and can, like the presolvated electron, reduce silver ions much faster than the H(•) atom. Moreover, it is found that with the same concentration of H3O(+) the reduction reaction is favored in the phosphoric acid solution compared to that in the perchloric acid solution because of the less-efficient electron solvation process. The kinetics show that among the three reducing species, (e(-), H3O(+)), (es(-), H3O(+)), and H(•) atom, the first one is the most efficient.

  14. Synthesis, Structure and Characterization of Three Metal Molybdate Hydrates: Fe(H2O)2(MoO4)2·H3O, NaCo2(MoO4)2(H3O2)and Mn2(MoO4)3·2H3O

    YU Yang; FENG Shou-hua; LIU Dan; HU Wei-wei; LI Jia; PENG Yu; ZHOU Qi; YANG Fen; LI Guang-hua; SHI Zhan


    Three metal molybdate hydrates,Fe(H2O)2(MoO4)2·H3O(FeMo),NaCo2(MoO4)2(H3O2)(CoMo)and Mn2(MoO4)3·2H3O(MnMo),were synthesized by the mixed-solvent-thermal methods and characterized by singlecrystal X-ray diffraction.X-Ray photoelectron spectroscopy and bond-valence sums were applied to confirming the valance of Fe,Co,Mn and Mo.Thermo-gravimetric analysis and X-ray powder diffraction measurements indicate that the samples were converted to different structural compounds upon heating in air at 600 ℃ for 1 h.The magnetic properties of these compounds were studied.The dominant magnetic interactions are antiferromagnetic in nature.However,different synthesis conditions led to the diversity of magnetic properties of compound CoMo.

  15. Towards a cross-border hydrogeological model: harmonized data integration within the H3O-projects

    Heyvaert, Vanessa M. A.; Vernes, Ronald W.; Deckers, Jef; Bogemans, Frieda; Deceukelaire, Marleen; Den Dulk, Maryke; Doornenbal, Hans C.; Dusar, Michiel; Hummelman, Jan; Kiden, Patrick; Lanckacker, Timothy; Menkovic, Armin; Meyvis, Bruno; Munsterman, Dirk K.; Reindersma, Reinder N.; ten Veen, Johan H.; van de Ven, Tamara J. M.; Walstra, Jan; Westerhoff, Wim E.; Witmans, Nora


    The sustainable use and management of natural resources in border regions requires unambiguous geological information from neighbouring countries. However, the available data often lack compatibility and the same level of detail across borders. Various stakeholders in the Netherlands and Flanders expressed their interest to harmonize the (hydro) geological models in the shared border region. Accordingly, the first H3O project was initiated in March 2012, focussing on the Roer Valley Graben across the Dutch-Flemish border. A second project (H3O-Campine area) set off in April 2015 and deals with the adjacent Campine area. Aim of these successive projects was (is) to produce cross-border, up-to-date, three-dimensional geological and hydrogeological models of the Cenozoic deposits. Existing (hydro) geological data (boreholes, well logs, seismic data, fault traces, geological maps and models) are collected, re-interpreted according to a harmonized lithostratigraphic scheme and fed into the 3D modelling process. Results of the first H3O-Roer Valley Graben project include: • A correlation scheme between Dutch and Belgian/Flemish (hydro) geological units; • A consistent fault model of the Roer Valley Graben; • Geometrically and stratigraphically consistent geological and hydrogeological models of the Cenozoic deposits in the Roer Valley Graben across the Dutch-Flemish border. The resulting 3D models can be considered as a state-of-the-art reference for the subsurface structure of the project area and can be used as a base for cross-border management of natural resources. The correlation scheme serves as a guideline for present (H3O-Campine area) and future cross-border projects. The H3O projects are carried out by a partnership between TNO - Geological Survey of the Netherlands, VITO and the Geological Survey of Belgium. The H3O models will be available in the public domain via the online data portals of DOV (Databank Ondergrond Vlaanderen) and DINOloket (Data en

  16. Cross sections for Scattering and Mobility of OH- and H3 O+ ions in H2 O

    Petrovic, Zoran; Stojanovic, Vladimir; Maric, Dragana; Jovanovic, Jasmina


    Modelling of plasmas in liquids and in biological and medical applications requires data for scattering of all charged and energetic particles in water vapour. We present swarm parameters for OH- and H3 O+, as representatives of principal negative and positive ions at low pressures in an attempt to provide the data that are not yet available. We applied Denpoh-Nanbu procedure to calculate cross section sets for collisions of OH- and H3 O+ ions with H2 O molecule. Swarm parameters for OH- and H3 O+ ions in H2 O are calculated by using a well tested Monte Carlo code for a range of E / N(E -electric field, N-gas density) at temperature T = 295 K, in the low pressure limit. Non-conservative processes were shown to strongly influence the transport properties even for OH- ions above the average energy of 0.2 eV(E / N >200 Td). The data are valid for low pressure water vapour or small amounts in mixtures. They will provide a basis for calculating properties of ion-water molecule clusters that are most commonly found at higher pressures and for modelling of discharges in liquids. Acknowledgment to Ministry of Education, Science and Technology of Serbia.

  17. The H3O-project: towards sustainable use and management of the Flemish-Dutch subsurface

    Vernes, Ronald W.; Deckers, Jef; Doornenbal, Hans C.; den Dulk, Maryke; Hummelman, Jan; Menkovic, Armin; Westerhoff, Wim; Witmans, Nora; Dusar, Michiel; Walstra, Jan; Reindersma, Reinder


    The collection and unambiguous interpretation and analysis of (hydro)geological information on both sides of the border are essential ingredients in the management of natural resources and use of the subsurface in the border region. The information currently available from the neighbouring countries often lacks compatibility and the same amount of detail. In 2012 the "H3O" project got under way which aims at a consistent interpretation of the subsurface in the Flemish-Dutch border region. Parties in the Netherlands (Provinces of Limburg and Noord-Brabant and TNO) and Flanders (The Environment, Nature and Energy Department of the Flemish Government, the Flemish Environment Agency, VITO and the Geological Survey of Belgium) are cooperating to harmonise the geological and hydrogeological models of the Netherlands (DGM and REGIS II) and Flanders (Geological 3D model and HCOV). This project is called "H3O" which stands for "(Hydro)geologische 3d-modellering Ondergrond". The H3O project focuses on the Roer Valley Graben that runs from Germany in a north-westerly direction over the central part of Limburg, the north-easterly part of the Belgian province of Limburg to Noord-Brabant and is bordered by major fault zones along the north and south perimeters. The aim of the project is to make a cross-border, up-to-date, three-dimensional geological and hydrogeological model of the Quaternary and Tertiary deposits in the Limburg, Southeast Brabant and Flemish part of this region. This will help to identify, study and rectify the differences between the existing (hydro)geological interpretations. The work is supervised by a committee of experts and carried out by VITO, the Belgian Geological Survey and the Geological Survey of the Netherlands of TNO. These organisations have extensive knowledge of the stratigraphy and regional geology as well as experience of creating 3D models of the subsurface (Geological 3D model of Flanders, DGM, REGIS, GeoTOP). Delivery and presentation of

  18. Observations of VOC emissions and photochemical products over US oil- and gas-producing regions using high-resolution H3O+ CIMS (PTR-ToF-MS

    A. Koss


    Full Text Available VOCs related to oil and gas extraction operations in the United States were measured by H3O+ chemical ionization time-of-flight mass spectrometry (H3O+ ToF-CIMS/PTR-ToF-MS from aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX campaign in March–April 2015. This work presents an overview of major VOC species measured in nine oil- and gas-producing regions, and a more detailed analysis of H3O+ ToF-CIMS measurements in the Permian Basin within Texas and New Mexico. Mass spectra are dominated by small photochemically produced oxygenates and compounds typically found in crude oil: aromatics, cyclic alkanes, and alkanes. Mixing ratios of aromatics were frequently as high as those measured downwind of large urban areas. In the Permian, the H3O+ ToF-CIMS measured a number of underexplored or previously unreported species, including aromatic and cycloalkane oxidation products, nitrogen heterocycles including pyrrole (C4H5N and pyrroline (C4H7N, H2S, and a diamondoid (adamantane or unusual monoterpene. We additionally assess the specificity of a number of ion masses resulting from H3O+ ion chemistry previously reported in the literature, including several new or alternate interpretations.

  19. Observations of VOC emissions and photochemical products over US oil- and gas-producing regions using high-resolution H3O+ CIMS (PTR-ToF-MS)

    Koss, Abigail; Yuan, Bin; Warneke, Carsten; Gilman, Jessica B.; Lerner, Brian M.; Veres, Patrick R.; Peischl, Jeff; Eilerman, Scott; Wild, Rob; Brown, Steven S.; Thompson, Chelsea R.; Ryerson, Thomas; Hanisco, Thomas; Wolfe, Glenn M.; St. Clair, Jason M.; Thayer, Mitchell; Keutsch, Frank N.; Murphy, Shane; de Gouw, Joost


    VOCs related to oil and gas extraction operations in the United States were measured by H3O+ chemical ionization time-of-flight mass spectrometry (H3O+ ToF-CIMS/PTR-ToF-MS) from aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX) campaign in March-April 2015. This work presents an overview of major VOC species measured in nine oil- and gas-producing regions, and a more detailed analysis of H3O+ ToF-CIMS measurements in the Permian Basin within Texas and New Mexico. Mass spectra are dominated by small photochemically produced oxygenates and compounds typically found in crude oil: aromatics, cyclic alkanes, and alkanes. Mixing ratios of aromatics were frequently as high as those measured downwind of large urban areas. In the Permian, the H3O+ ToF-CIMS measured a number of underexplored or previously unreported species, including aromatic and cycloalkane oxidation products, nitrogen heterocycles including pyrrole (C4H5N) and pyrroline (C4H7N), H2S, and a diamondoid (adamantane) or unusual monoterpene. We additionally assess the specificity of a number of ion masses resulting from H3O+ ion chemistry previously reported in the literature, including several new or alternate interpretations.

  20. Solvent extraction of Li+, H3O+ and NH4+ into nitrobenzene by using sodium dicarbollylcobaltate and calix[4]arene-bis(t-octylbenzo-18-crown-6)

    Makrlik, Emanuel [Czech University of Life Sciences, Prague, Kamy´cká; Selucky, P. [Nuclear Research Institute, Rez, Czech Republic; Vanura, Petr [Institute of Chemical Technology, Prague, Czech Republic; Moyer, Bruce A [ORNL


    From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+ (aq) + NaL+ (nb) , ML+ (nb) + Na+ (aq) taking place in the two-phase water nitrobenzene system (M+ = Li+, H3O+, NH+4; L = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML+ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: zH3O+ < Li+ < NH+4.

  1. Interstellar OH+, H2O+ and H3O+ along the sight-line to G10.6-0.4

    Gerin, Maryvonne; Black, John; Herbst, Eric; Goicoechea, Javier R; Falgarone, Edith; Godard, Benjamin; Pearson, John C; Lis, Dariucz C; Phillips, Thomas G; Bell, Thomas A; Sonnentrucker, Paule; Boulanger, Francois; Cernicharo, José; Coutens, Audrey; Dartois, Emmanuel; Encrenaz, Pierre; Giesen, Thomas; Goldsmith, Paul F; Gupta, Harshal; Gry, Cecile; Hennebelle, Patrick; Hily-Blant, Pierre; Joblin, Christine; Kazmierczak, Maja; Kolos, Robert; Krelowski, Jacek; Martin-Pintado, Jesus; Monje, Raquel; Mookerjea, Bhaswati; Pérault, Michel; Persson, Carina; Plume, René; Rimmer, Paul B; Salez, Morvan; Schmidt, Mirisloaw; Teyssier, David; Vastel, Charlotte; Yu, Shan Shan; Contursi, Alessandra; Menten, Karl; Geballe, Thomas; Schlemmer, Stephan; Shipman, Russ; Tielens, Alexander G G M; Philipp-May, Sabine; Cros, Alain; Zmuidzinas, Jonas; Samoska, L A; Klein, K; Neufeld, D A; Lorenzani, A; Stutzki, Jürgen


    We report the detection of absorption lines by the reactive ions OH+, H2O+ and H3O+ along the line of sight to the submillimeter continuum source G10.6$-$0.4 (W31C). We used the Herschel HIFI instrument in dual beam switch mode to observe the ground state rotational transitions of OH+ at 971 GHz, H2O+ at 1115 and 607 GHz, and H3O+ at 984 GHz. The resultant spectra show deep absorption over a broad velocity range that originates in the interstellar matter along the line of sight to G10.6$-$0.4 as well as in the molecular gas directly associated with that source. The OH+ spectrum reaches saturation over most velocities corresponding to the foreground gas, while the opacity of the H2O+ lines remains lower than 1 in the same velocity range, and the H3O+ line shows only weak absorption. For LSR velocities between 7 and 50 kms$^{-1}$ we estimate total column densities of $N$(OH+) $> 2.5 \\times 10^{14}$ cm$^{-2}$, $N$(H2O+) $\\sim 6 \\times 10^{13}$ cm$^{-2}$ and $N$(H3O+) $\\sim 4.0 \\times 10^{13}$ cm$^{-2}$. These de...

  2. Dissociation of protonated oxalic acid [HOOC-C(OH)2]+ into H3O+ + CO + CO2: An experimental and CBS-QB3 computational study

    Ervasti, Henri K.; Lee, Richard; Burgers, Peter C.; Ruttink, Paul J. A.; Terlouw, Johan K.


    The predominant dissociation process observed for metastable protonated oxalic acid ions HOOC-C(OH)2+ (generated by self-protonation) leads to H3O++ CO + CO2. We have traced the mechanism of this intriguing reaction using the CBS-QB3 model chemistry. Our calculations show that a unique ter-body complex, OCO...H3O+...CO, plays a key role in the rearrangement process. This complex can also dissociate to the proton bound dimers [H2O...H...OCO]+ and [H2O...H...CO]+ which are minor processes observed in the metastable ion mass spectrum. A further minor process leads to the proton bound dimer OCO...H+...CO which is formed by water extrusion from the ter-body complex. Arguments are provided that the ter-body complex is also generated in the ion source by the collision encounter between neutral and ionized oxalic acid.

  3. Extended Measurement of the v2(1- ← 0+) Band of H3O+ by Mid-Infrared Diode Laser Spectroscopy

    ZHENG Rui; WANG Rui-Bo; LI Song; HUANG Guang-Ming; DUAN Chuan-Xi


    Twenty-five new R-branch lines of the v2 (1- ← 0+) band of H3O+ are measured using diode laser velocity modulation spectroscopy between 1070 and 1230 cm-1. The H3 O+ ions are produced in a high voltage ac discharge with water diluted in helium. The observed lines together with all the previously published measurements are fit to the standard vibration-rotational Hamiltonian of an oblate symmetric top, yielding a set of improved molecular constants. All the sextic centrifugal distortion constants for both 0+ and 1- states are determined precisely. The observed R(13, 0) transition is shifted about -0.129 cm-1 from its calculated value, indicating that a near degeneracy exists between the (13, 0)+ and (13, 3)- ground-state rotation-inversion levels.

  4. Hyperpolarizabilities of Chelidamic Acid Complexes M_m(C_7H_3O_5N)_n (M=Cu, Ag): Theoretical Analysis

    ZHANG, Xin; ZHOU, Guowei; TAN, Kai; GUO, Guocong; LIN, Menghai; ZHANG, Qianer


    The frequency-dependent hyperpolarizabilities of cbelidamic acid complexes M_m(C_7H_3O_5N)n (M=Cu, Ag) were investigated under the time dependent density functional theory (TDDFT) combined with the sum-over-states method (SOS). The relationship between molecular orbitals and nonlinear optical (NLO) properties has been explored. The results show that the charge transitions of π-π~* and 3d_M-π~* are very important to the second-order polarizabilities, and the largest component of dynamic β is 3.84×10~(-25) cm~5·esu~(-1) at 0.74 eV for Ag_2Cu_2(C_7H_3O_5N)_4.The charge transition between π-π~* is also highly crucial to the third-order polarizabilities, and the largest component of dynamic γ is -4.46×10~(-29) esu at 0.50 eV for Ag_2Cu_2(C_7H_3O_5N)_4. The central Cu ion, as electron bridge,extends the range of delocalization and leads to an interesting phenomenon of piroconjugation.

  5. Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate

    Indriolo, Nick; Gerin, M; Schilke, P; Benz, A O; Winkel, B; Menten, K M; Chambers, E T; Black, John H; Bruderer, S; Falgarone, E; Godard, B; Goicoechea, J R; Gupta, H; Lis, D C; Ossenkopf, V; Persson, C M; Sonnentrucker, P; van der Tak, F F S; van Dishoeck, E F; Wolfire, Mark G; Wyrowski, F


    In diffuse interstellar clouds the chemistry that leads to the formation of the oxygen bearing ions OH+, H2O+, and H3O+ begins with the ionization of atomic hydrogen by cosmic rays, and continues through subsequent hydrogen abstraction reactions involving H2. Given these reaction pathways, the observed abundances of these molecules are useful in constraining both the total cosmic-ray ionization rate of atomic hydrogen (zeta_H) and molecular hydrogen fraction, f(H2). We present observations targeting transitions of OH+, H2O+, and H3O+ made with the Herschel Space Observatory along 20 Galactic sight lines toward bright submillimeter continuum sources. Both OH+ and H2O+ are detected in absorption in multiple velocity components along every sight line, but H3O+ is only detected along 7 sight lines. From the molecular abundances we compute f(H2) in multiple distinct components along each line of sight, and find a Gaussian distribution with mean and standard deviation 0.042+-0.018. This confirms previous findings t...

  6. Effects of H3O+, OH-, \\text{O}_{2}^{-} , \\text{NO}_{\\text{x}}^{-} and NO x for Escherichia coli inactivation in atmospheric pressure DC corona discharges

    Sekimoto, Kanako; Gonda, Rena; Takayama, Mitsuo


    The effects of ionic and neutral species such as H3O+, OH-, \\text{O}2- , \\text{NO}x- (x = 2, 3), and NO x on Escherichia coli (E. coli) inactivation in gas and liquid phases was investigated using atmospheric pressure DC corona discharges with point-to-plane electrodes. The above chemical species as well as OH and O3 were selectively irradiated onto E. coli suspensions on agar plates using a needle angle of 45° with respect to the plates, airflow, and a grid plate. Irradiation with the positive ion H3O+ did not inactivate E. coli, while the negative ions OH-/\\text{O}2- resulted in bactericidal inactivation, in both gas and liquid phases. In contrast, the negative ions \\text{NO}x- and neutral species NO x in the gas phase had quite strong bactericidal effects on E. coli compared to those species in the liquid phase. These results suggest that liquid-phase HNO3, formed primarily via the reaction of gas-phase \\text{NO}x- and NO x with H2O in agar, has only a weak inactivation effect on E. coli. Furthermore, using naphthylethylenediamine spectrophotometry, the threshold amount of gas-phase \\text{NO}x- and NO x for E. coli inactivation was determined to be  ≈1.3   ×   10-9 mol mm-1.

  7. Silicate glass and mineral dissolution: calculated reaction paths and activation energies for hydrolysis of a q3 si by H3O+ using ab initio methods.

    Criscenti, Louise J; Kubicki, James D; Brantley, Susan L


    Molecular orbital energy minimizations were performed with the B3LYP/6-31G(d) method on a [((OH)3SiO)3SiOH-(H3O+).4(H2O)] cluster to follow the reaction path for hydrolysis of an Si-O-Si linkage via proton catalysis in a partially solvated system. The Q3 molecule was chosen (rather than Q2 or Q1) to estimate the maximum activation energy for a fully relaxed cluster representing the surface of an Al-depleted acid-etched alkali feldspar. Water molecules were included in the cluster to investigate the influence of explicit solvation on proton-transfer reactions and on the energy associated with hydroxylating the bridging oxygen atom (Obr). Single-point energy calculations were performed with the B3LYP/6-311+G(d,p) method. Proton transfer from the hydronium cation to an Obr requires sufficient energy to suggest that the Si-(OH)-Si species will occur only in trace quantities on a silica surface. Protonation of the Obr lengthens the Si-Obr bond and allows for the formation of a pentacoordinate Si intermediate ([5]Si). The energy required to form this species is the dominant component of the activation energy barrier to hydrolysis. After formation of the pentacoordinate intermediate, hydrolysis occurs via breaking the [5]Si-(OH)-Si linkage with a minimal activation energy barrier. A concerted mechanism involving stretching of the [5]Si-(OH) bond, proton transfer from the Si-(OH2)+ back to form H3O+, and a reversion of [5]Si to tetrahedral coordination was predicted. The activation energy for Q3Si hydrolysis calculated here was found to be less than that reported for Q3Si using a constrained cluster in the literature but significantly greater than the measured activation energies for the hydrolysis of Si-Obr bonds in silicate minerals. These results suggest that the rate-limiting step in silicate dissolution is not the hydrolysis of Q3Si-Obr bonds but rather the breakage of Q2 or Q1Si-Obr bonds.

  8. Synthesis and Crystal Structure of (H3O)2[Cu3Cl3(H2O)3(NC9H12.5O6)2


    The new compound, (H3O)2[Cu3Cl3(H2O)3(NCgH12.5O6)2] 1, has been synthesized by the hydrothermal reaction and its structure was determined by single-crystal X-ray diffraction.The crystal is of hexagonal, space group P63/m with a = 10.6975(13), c = 14.881 (3)A, V = 1474.8(4)866, R = 0.0517 and wR = 0.0900 for 537 observed reflections (I > 2σ(Ⅰ)). This compound contains two oxonium ions and one [Cu3C13(H2O)3(H0.5ntp)2]2- anion (ntp = nitrilotripropanoato), in which two tridentate ntp ligands connected by three copper(Ⅱ) ions enclose a cage-like unit. Each copper(Ⅱ) ion is coordinated by one water molecule, one chloride ligand and two carboxylate oxygen atoms from two ntp ligands assume a slightly distorted square-planar geometry. There are atoms of the units resulting in two-dimensional sheets and wheel-like three-dimensional interpenetrating frameworks.

  9. H3O+, NO+和O+·2离子同九种烷氧基醇化合物反应的研究%A Study of the Reactions of H3O+, NO+ and O+·2 Ions with Nine Alkoxy Alcohols



    在用选择离子流动管质谱(SIFT-MS)分析常用指甲油清洗垫发现大量4-丁酸内脂(γ-butyrolactone, GBL)和2-丁氧基乙醇(2-butoxy-1-ethanol)等挥发性气体后, 运用选择离子流动管(SIFT)对H3O+, NO+和O+·2离子同九种烷氧基醇化合物(R1-O-R2OH)之间的反应进行了研究. 获得了这些反应在潮湿空气条件下进行的情况, 并运用产物离子水合物的种类和分布来确认产物离子的结构和反应机理. 还研究了在不同载气压力下进行的反应. 结果表明, 这些化合物同H3O+和NO+的反应都是先生成初生态离子-分子络合物, (H3O+.M)*和(NO+.M)*, 然后经不同反应渠道生成各种离子产物. 这些初生态络合物同反应体系中存在的气体分子(如氦气, 氮气和氧气分子)的碰撞对最终离子产物的形成和分布也有影响. 这些化合物同O2+·反应会生成各种离解碎片离子, 但不能确定这些离子是否经由初生态络合物(O2+·.M)*生成. 该项研究提供了用SIFT-MS在空气和潮湿气体中分析这些化合物所需的反应速率常数和离子产物等动力学数据, 并将进一步应用到药物成瘾及滥用和呼吸道疾病的诊断和分析等领域.%Following a selected ion flow tube mass spectrometry(SIFT-MS), analysis of the headspace of a commercial available nail polish remover pad in which γ-butyrolactone (GBL) and 2-butoxy-1-ethanol were found to be the major volatiles, a study of the reactions of H3O+, NO+ and O+·2 ions with nine alkoxy alcohols (R1-O-R2OH) was carried out using selected ion flow tube(SIFT) at a carrier gas (helium) pressure of 9.3×101 Pa. Experiments were also performed at various carrier gas pressures (4×101-1.1×102 Pa) for some reactions and under moist air condition. The number and distribution of the hydrates for the product ions were used to identify their structures and to investigate reaction mechanisms. The H3O+ reactions proceed via nascent ion-molecule complex (H3

  10. A high-resolution time-of-flight chemical ionization mass spectrometer utilizing hydronium ions (H3O+ ToF-CIMS) for measurements of volatile organic compounds in the atmosphere

    Yuan, Bin; Koss, Abigail; Warneke, Carsten; Gilman, Jessica B.; Lerner, Brian M.; Stark, Harald; de Gouw, Joost A.


    Proton transfer reactions between hydronium ions (H3O+) and volatile organic compounds (VOCs) provide a fast and highly sensitive technique for VOC measurements, leading to extensive use of proton-transfer-reaction mass spectrometry (PTR-MS) in atmospheric research. Based on the same ionization approach, we describe the development of a high-resolution time-of-flight chemical ionization mass spectrometer (ToF-CIMS) utilizing H3O+ as the reagent ion. The new H3O+ ToF-CIMS has sensitivities of 100-1000 cps ppb-1 (ion counts per second per part-per-billion mixing ratio of VOC) and detection limits of 20-600 ppt at 3σ for a 1 s integration time for simultaneous measurements of many VOC species of atmospheric relevance. The ToF analyzer with mass resolution (m/Δm) of up to 6000 allows the separation of isobaric masses, as shown in previous studies using similar ToF-MS. While radio frequency (RF)-only quadrupole ion guides provide better overall ion transmission than ion lens system, low-mass cutoff of RF-only quadrupole causes H3O+ ions to be transmitted less efficiently than heavier masses, which leads to unusual humidity dependence of reagent ions and difficulty obtaining a humidity-independent parameter for normalization. The humidity dependence of the instrument was characterized for various VOC species and the behaviors for different species can be explained by compound-specific properties that affect the ion chemistry (e.g., proton affinity and dipole moment). The new H3O+ ToF-CIMS was successfully deployed on the NOAA WP-3D research aircraft for the SONGNEX campaign in spring of 2015. The measured mixing ratios of several aromatics from the H3O+ ToF-CIMS agreed within ±10 % with independent gas chromatography measurements from whole air samples. Initial results from the SONGNEX measurements demonstrate that the H3O+ ToF-CIMS data set will be valuable for the identification and characterization of emissions from various sources, investigation of secondary

  11. Low-Lying Energy Isomers and Global Minima of Aqueous Nanoclusters: Structures and Spectroscopic Features of the Pentagonal Dodecahedron (H2O)20 and (H3O)+(H2O)20

    Xantheas, Sotiris S.


    We rely on a hierarchy of methods to identify the low-lying isomers for the pentagonal dodecahedron (H2O)20 and the H3O+(H2O)20 clusters. Initial screening of isomers was performed with classical potentials [TIP4P, TTM2-F, TTM2.1-F for (H2O)20 and ASP for H3O+(H2O)20] and the networks obtained with those potentials were subsequently reoptimized at the DFT (B3LYP) and MP2 levels of theory. For the pentagonal dodecahedron (H2O)20 it was found that DFT (B3LYP) and MP2 produced the same global minimum. However, this was not the case for the H3O+(H2O)20 cluster, for which MP2 produced a different network for the global minimum when compared to DFT (B3LYP). All low-lying minima of H3O+(H2O)20 correspond to hydrogen bonding networks having 9 ''free'' OH bonds and the hydronium ion on the surface of the cluster. The fact that DFT (B3LYP) and MP2 produce different results and issues related to the use of a smaller basis set, explains the discrepancy between the current results and the structure previously suggested [Science 304, 1137 (2004)] for the global minimum of the H3O+(H2O)20 cluster. Additionally, the IR spectra of the MP2 global minimum are closer to the experimentally measured ones than the spectra of the previously suggested DFT global minimum. The latter exhibit additional bands in the most red-shifted region of the OH stretching vibrations (corresponding to the ''fingerprint'' of the underlying hydrogen bonding network), which are absent from both the experimental as well as the spectra of the new structure suggested for the global minimum of this cluster.

  12. The Structure and Spectral Research on Mn2 [ V12 B16O52 (OH)6 ] (en) 2 (H3O)6 (H2O) 5 (en=ethylenediamine)%Mn2[ V12B16O52(OH)6](en)2(H3O)6(H2O)5(en=ethylenediamine)的结构及谱学研究

    李光满; 梅洪鑫; 邓松; 孙燕琼; 胡恒彬; 陈义平; 张汉辉


    采用水热合成法合成了一种结构新颖的多硼钒氧簇化合物Mn2 [V12B16O52 (OH)6] (en)2( H3O)6(H2O)5(en=ethylenediamine)1,通过单晶X射线衍射确定该化合物的结构.化合物1中,在ab平面上,簇单元之间通过[Mn(H2 O)2]2+连接成二维层状结构,另外,层与层之间在c方向上通过氢键连接成三维空间结构.此外,对化合物1的谱学性质进行了红外光谱、磁和热微扰下的二维红外相关光谱、紫外-可见固体漫反射光谱分析,探讨了其结构与谱学性质的关系.磁微扰的二维红外相关光谱表明B-O,V-O-V和Mn-O-B的伸缩振动对于磁场的变化比较敏感,热微扰的二维红外相关光谱表明B-OH,B-O,V-O-V和Mn-O-B的伸缩振动对热微扰比较敏感.%A novel polyoxovanadium borate Mn2[V12B16O52 (OH)6](en)2 (H3O)6 (H2O)5 l(en=ethylenediamine) was hydro-thermally synthesized and characterized by IR, two-dimensional infrared (2D IR) correlation spectroscopy with magnetic and thermal perturbation, and single crystal X-ray diffraction. In 1, it is interesting that each [V12B16O52 (OH)6]14- units is connected by four [Mn(H2O)2]2+ to generate a 2D layer on the ab plane. Along c axis, these layers are further linked by H-bond to form a 3D framework. The response of the stretching vibrations of B-O, V-O-V and Mn-O-B was detected in the 2D IR correlation spectra with magnetic perturbatioa In addition, the response of the stretching vibrations of B-OH, B-O, V-O- V and Mn-O-B was detected in the 2D IR correlation spectra with thermal perturbation.

  13. Stepwise formation of H3O+(H2O)n in an ion drift tube: Empirical effective temperature of association/dissociation reaction equilibrium in an electric field

    Nakai, Yoichi; Hidaka, Hiroshi; Watanabe, Naoki; Kojima, Takao M.


    We measured equilibrium constants for H3O+(H2O)n-1 + H2O↔H3O+(H2O)n (n = 4-9) reactions taking place in an ion drift tube with various applied electric fields at gas temperatures of 238-330 K. The zero-field reaction equilibrium constants were determined by extrapolation of those obtained at non-zero electric fields. From the zero-field reaction equilibrium constants, the standard enthalpy and entropy changes, Δ Hn , n - 1 0 and Δ Sn , n - 1 0 , of stepwise association for n = 4-8 were derived and were in reasonable agreement with those measured in previous studies. We also examined the electric field dependence of the reaction equilibrium constants at non-zero electric fields for n = 4-8. An effective temperature for the reaction equilibrium constants at non-zero electric field was empirically obtained using a parameter describing the electric field dependence of the reaction equilibrium constants. Furthermore, the size dependence of the parameter was thought to reflect the evolution of the hydrogen-bond structure of H3O+(H2O)n with the cluster size. The reflection of structural information in the electric field dependence of the reaction equilibria is particularly noteworthy.

  14. Stepwise formation of H3O(+)(H2O)n in an ion drift tube: Empirical effective temperature of association/dissociation reaction equilibrium in an electric field.

    Nakai, Yoichi; Hidaka, Hiroshi; Watanabe, Naoki; Kojima, Takao M


    We measured equilibrium constants for H3O(+)(H2O)n-1 + H2O↔H3O(+)(H2O)n (n = 4-9) reactions taking place in an ion drift tube with various applied electric fields at gas temperatures of 238-330 K. The zero-field reaction equilibrium constants were determined by extrapolation of those obtained at non-zero electric fields. From the zero-field reaction equilibrium constants, the standard enthalpy and entropy changes, ΔHn,n-1 (0) and ΔSn,n-1 (0), of stepwise association for n = 4-8 were derived and were in reasonable agreement with those measured in previous studies. We also examined the electric field dependence of the reaction equilibrium constants at non-zero electric fields for n = 4-8. An effective temperature for the reaction equilibrium constants at non-zero electric field was empirically obtained using a parameter describing the electric field dependence of the reaction equilibrium constants. Furthermore, the size dependence of the parameter was thought to reflect the evolution of the hydrogen-bond structure of H3O(+)(H2O)n with the cluster size. The reflection of structural information in the electric field dependence of the reaction equilibria is particularly noteworthy.

  15. Oxonium ions substituting cesium ions in the structure of the new high-pressure borate HP-Cs(1-x)(H(3)O)(x)B(3)O(5) (x=0.5-0.7).

    Sohr, Gerhard; Neumair, Stephanie C; Heymann, Gunter; Wurst, Klaus; Schmedt auf der Günne, Jörn; Huppertz, Hubert


    The new high-pressure borate HP-Cs1-x (H3 O)x B3 O5 (x=0.5-0.7) was synthesized under high-pressure/high-temperature conditions of 6 GPa/900 °C in a Walker-type multianvil apparatus. The compound crystallizes in the monoclinic space group C2/c (Z=8) with the parameters a=1000.6(2), b=887.8(2), c=926.3(2) pm, β=103.1(1)°, V=0.8016(3) nm(3) , R1=0.0452, and wR2=0.0721 (all data). The boron-oxygen network is analogous to those of the compounds HP-MB3 O5 , (M=K, Rb) and exhibits all three structural motifs of borates-BO3 groups, corner-sharing BO4 tetrahedra, and edge-sharing BO4 tetrahedra-at the same time. Channels inside the boron-oxygen framework contain the cesium and oxonium ions, which are disordered on a specific site. Estimating the amount of hydrogen by solid-state NMR spectroscopy and X-ray diffraction led to the composition HP-Cs1-x (H3 O)x B3 O5 (x=0.5-0.7), which implies a nonzero phase width.

  16. Copper(II) ion catalytic oxidation of o-phenylenediamine and characterization, X-ray crystal structure and solution studies of the final product [DAPH][H3O][Cu(dipic)2]·3H2O

    Ghasemi, Khaled; Rezvani, Ali Reza; Shokrollahi, Ardeshir; Abdul Razak, Ibrahim; Refahi, Masoud; Moghimi, Abolghasem; Rosli, Mohd Mustaqim


    The complex [DAPH][H3O][Cu(dipic)2]·3H2O, (1) (dipicH2 = 2,6-pyridinedicarboxylic acid and DAP = 2,3-diaminophenazine) was prepared from the reaction of Cu(NO3)2·2H2O with mixture of o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid in water. The complex was characterized by FTIR, elemental analysis, UV-Vis and the single-crystal X-ray diffraction. The crystal system is monoclinic with the space group P21/c. This complex is stabilized in the solid state by an extensive network of hydrogen bonds between crystallized water, anionic and cationic fragments, which form a three-dimensional network. Furthermore, hydrogen bonds, π⋯π and Csbnd O⋯π stacking interactions seem to be effective in stabilizing the crystal structures. The protonation constants of dipic (L) and DAP (Q), the equilibrium constants for the dipic-DAP proton transfer system and the stoichiometry and stability constants of binary complexes including each of ligands (dipic, DAP) in presence Cu2+ ion, ternary complexes including, both of ligands (dipic-DAP) in presence of metal ion were calculated in aqueous solutions by potentiometric pH titration method using the Hyperquad2008 program. The stoichiometry of the most complexes species in solution was found to be very similar to the solid-state of cited metal ion complex.

  17. Synthesis, Properties and Crystal Structure of a Novel Coordinated Polymer: {(H2en)(H3O)[(BiPb(C2O4)4(H2O)2)]·2(H2O)}n

    GUO Wen-Jun; ZHANG Han-Hui; HUANG Chang-Cang; SUN Rui-Qing; CHEN Yi-Ping; CAO Yan-Ning


    A novel oxalate compound {(H2en)(H3O)[BiPb(C2O4)4(H2O)2]·2(H2O)}n 1 (en = ethylenediamine) containing lead and bismuth has been synthesized by hydrothermal methods, and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P21/c with a = 11.6160(1), b = 12.7426(1), c = 15.5683(5) (A), β = 108.442(4)°, BiPbC10N2O21H21, Mr = 921.46, V = 2186.0(4) (A)3, Z = 4, Dc = 2.800 g/cm3, F(000) = 1712 and μ(MoKα) = 15.837 mm-1. The final R = 0.0502 and wR = 0.1261 for 3391 observed reflections with I > 2(σI). The title com- pound consists of 2-D polyanions and protonized organic amine cations, and they are combined to each other by static attractive force and H-bonds to form the so-called organic-inorganic hybrid material.

  18. Ax(H3O)2-xMn5(HPO3)6 (A = Li, Na, K and NH4): open-framework manganese(ii) phosphites templated by mixed cationic species.

    Orive, Joseba; Fernández de Luis, Roberto; Fernández, Jesús Rodríguez; Lezama, Luis; Arriortua, María I


    Ax(H3O)2-xMn5(HPO3)6 (A = Li, x = 0.55 (1-Li); A = Na, x = 0.72 (2-Na); A = K, x = 0.30 (3-K); A = NH4, x = 0.59 (4-NH4)) phases were synthesized by employing mild hydrothermal conditions. 1-Li was studied by single crystal X-ray diffraction, while sodium, potassium and ammonium containing analogues were obtained as polycrystalline samples and characterized by powder X-ray diffraction. The four compounds were characterized by ICP-Q-MS, thermal analysis and XPS, IR, UV/Vis and EPR spectroscopy. Single crystal data indicate that 1-Li crystallizes in the P3[combining macron]c1 space group with lattice parameters a = 10.3764(1) Å and c = 9.4017(1) Å with Z = 2. The crystal structure of these phases is constituted by a three-dimensional [Mn(ii)5(HPO3)6](2-) anionic skeleton templated by alkali metal and ammonium cations together with protonated water molecules. Such an inorganic framework is formed by layers of edge-sharing MnO6 octahedra placed in the ab plane and joined along the c direction through phosphite pseudotetrahedra. The sheets display 12-membered ring channels parallel to the c-axis, ca. 5 Å in diameter, where the extraframework species display a strong disorder. EPR measurements point to the existence of short range ferromagnetic interactions around 12 K. Magnetic susceptibility and heat capacity measurements show that all the compounds exhibit long range antiferromagnetic order below circa 4 K, with a significant magnetocaloric effect around the Neel temperature.

  19. Weak C-H$\\cdots$F-C interactions in carboxylate anion binding: Synthesis, spectroscopic and X-ray structural studies of [Co(phen)2CO3]2 (C7H3O2FCl)Cl$\\cdots$11H2O and [Co(phen)2CO3](C7H3NO4Cl)$\\cdot$6H2O

    A Singh; R P Sharma; T Aree; P Venugopalan


    Two new complex salts containing 2,5-substituted benzoate ions, [Co(phen)2CO3]2 (C7H3O2FCl)Cl$\\cdot$11H2O (1) and [Co(phen)2CO3](C7H3NO4Cl)$\\cdot$6H2O (2) (where phen = 1,10-phenanthroline, C7H3O2FCl = 2-chloro-5-fluorobenzoate (cfbz) and C7H3NO4Cl = 2-chloro-5-nitrobenzoate(cnbz)) were synthesized by reacting carbonatobis(1,10-phenanthroline)cobalt(III) chloride with appropriate salts in aqueous medium. A detailed packing analysis has been undertaken to delineate the role of second sphere C-H$\\cdots$F and C-H$\\cdots$O interactions amid other heteroatom interactions. The complex salts have been characterized by elemental analyses, spectroscopic studies (IR, UV/Visible, multinuclear NMR), conductance and solubility product measurements. Single crystal X-ray structure determination revealed ionic structures of both the complex salts having discrete ions along with lattice water molecules. Crystal lattice is stabilized by a variety of hydrogen bonding interactions, i.e. O-H$\\cdots$O, C-H$\\cdots$O and C-H$\\cdots$F involving second sphere coordination besides - interaction. Furthermore, packing analyses reveal that C-H…F interactions can manifest even in the presence of a large number of heteroatom interactions.

  20. H3 : o melhor layout para um serviço “not so fast (food)”


    Dissertação de Mestrado em Gestão / Classificação JEL: L89 – Other Industry Studies: Services M10 – General Business Administration Num sector altamente competitivo como o do fast food, uma empresa portuguesa formada por três amigos resolveu diferenciar-se dos demais players e criar a h3, a empresa de fast food portuguesa especializada em hambúrgueres gourmet. Com o nascimento da h3, surgiu uma promessa de serviço que anunciava ao cliente da h3 apenas ter de esperar, em média, ...

  1. A full-dimensional quantum dynamical study of the vibrational ground state of $H_3O_2^-$ and its isotopomers

    Yang, Yonggang


    We investigated the effect of deuteration on the vibrational ground state of the hydrated hydroxide anion using a nine-dimensional quantum dynamical model for the case of J=0. The propagation of the nuclear wave function has been performed with the multi-configuration time-dependent Hartree method which yielded zero-point energies for the normal and fully deuterated species in quantitative agreement with previous diffusion Monte Carlo calculations. According to the zero-point energy the isotopomers having the hydrogen atom in the bridging position are more stable by about 1 kJ/mol as compared to the deuterium case. This holds irrespective of the deuteration state of the two OH groups. We also report the secondary geometric H/D isotope effect on the O--O distance which amounts to an elongation of about 0.005 A for the symmetric isotopomers and 0.009 A in the asymmetric case. Finally, we explore the isotopomer sensitivity of the ground state tunneling splitting due to the torsional motion of the two OH groups.

  2. EPR and optical investigation of VO(II) in Zn(C3H3O4)2(H2O)2 single crystals: An interstitial site

    Natarajan, B.; Mithira, S.; Deepa, S.; Sambasivarao, P.


    EPR spectroscopic investigations on single crystals of diaquabis[malonato(1-)-κ2O,O‧] zinc(II) doped with VO(II) ion have been carried out at X-band frequencies and at 300 K. The single crystal, rotated along the three mutually orthogonally axes, has yielded spin-Hamiltonian parameters g and A as: gxx=1.980, gyy=1.972, gzz=1.937 and Axx=8.4, Ayy=6.1, Azz=18.1 mT, respectively. These spin-Hamiltonian parameters reflect a slight deviation from axial symmetry to rhombic, which is elucidated by the interstitial occupation of vanadyl ions. The isofrequency plots and powder EPR spectrum have been simulated. The percentage of metal-oxygen bond has been estimated. The optical absorption spectrum exhibits four bands at 257, 592, 720 and 764 nm suggesting a C4v symmetry. The admixture coefficients and bonding parameters have also been calculated by collaborating EPR data with optical data.

  3. Hydrothermal Synthesis and Crystal Structure of a Novel Polymolybdic(VI) Acid: {[H3O]2+[Mo2O4(OH)6]2-}n

    WANG Wei-Dong; HU Mao-Lin


    A novel supramolecular polymolybdic(VI) acid was unexpectedly synthesized by the reaction of sodium molybdate with 1,2,4,5-benzenetetracarboxylic and trichloroacetic acids in 1:1:1 molar ratio under hydrothermal condition. The crystal belongs to tetragonal with space group P4/mbm, a = 0.88867(17), b = 0.88867(17), c = 0.55676(15) nm, Z = 3, V = 0.43969(17) nm3, Dc = 4.486 g/cm3, μ = 4.365 mm-1, F(000) = 576, R = 0.0273 and wR = 0.0679. In the crystal, the Mo(VI) atoms are six- and five-coordinated in distorted octahedral and trigonal bipyramidal geometries, respectively. Furthermore, these Mo(VI) atoms, bearing different coordinated environments, are bridged by OH groups with disorder O atoms to form a two-dimensional framework with pentagonal grids. It is worthy of notice that these adjacent two-dimensional frameworks are extended into a three-dimensional supramolecular array with pentagonal large cavities'by Van Der Waals' forces and hydrogen bonding interactions.

  4. Hidden role of intermolecular proton transfer in the anomalously diffuse vibrational spectrum of a trapped hydronium ion.

    Craig, Stephanie M; Menges, Fabian S; Duong, Chinh H; Denton, Joanna K; Madison, Lindsey R; McCoy, Anne B; Johnson, Mark A


    We report the vibrational spectra of the hydronium and methyl-ammonium ions captured in the C3v binding pocket of the 18-crown-6 ether ionophore. Although the NH stretching bands of the CH3NH3(+) ion are consistent with harmonic expectations, the OH stretching bands of H3O(+) are surprisingly broad, appearing as a diffuse background absorption with little intensity modulation over 800 cm(-1) with an onset ∼400 cm(-1) below the harmonic prediction. This structure persists even when only a single OH group is present in the HD2O(+) isotopologue, while the OD stretching region displays a regular progression involving a soft mode at about 85 cm(-1) These results are rationalized in a vibrationally adiabatic (VA) model in which the motion of the H3O(+) ion in the crown pocket is strongly coupled with its OH stretches. In this picture, H3O(+) resides in the center of the crown in the vibrational zero-point level, while the minima in the VA potentials associated with the excited OH vibrational states are shifted away from the symmetrical configuration displayed by the ground state. Infrared excitation between these strongly H/D isotope-dependent VA potentials then accounts for most of the broadening in the OH stretching manifold. Specifically, low-frequency motions involving concerted motions of the crown scaffold and the H3O(+) ion are driven by a Franck-Condon-like mechanism. In essence, vibrational spectroscopy of these systems can be viewed from the perspective of photochemical interconversion between transient, isomeric forms of the complexes corresponding to the initial stage of intermolecular proton transfer.

  5. Mutations Inactivating Herpes Simplex Virus 1 MicroRNA miR-H2 Do Not Detectably Increase ICP0 Gene Expression in Infected Cultured Cells or Mouse Trigeminal Ganglia.

    Pan, Dongli; Pesola, Jean M; Li, Gang; McCarron, Seamus; Coen, Donald M


    Herpes simplex virus 1 (HSV-1) latency entails the repression of productive ("lytic") gene expression. An attractive hypothesis to explain some of this repression involves inhibition of the expression of ICP0, a lytic gene activator, by a viral microRNA, miR-H2, which is completely complementary to ICP0 mRNA. To test this hypothesis, we engineered mutations that disrupt miR-H2 without affecting ICP0 in HSV-1. The mutant virus exhibited drastically reduced expression of miR-H2 but showed wild-type levels of infectious virus production and no increase in ICP0 expression in lytically infected cells, which is consistent with the weak expression of miR-H2 relative to the level of ICP0 mRNA in that setting. Following corneal inoculation of mice, the mutant was not significantly different from wild-type virus in terms of infectious virus production in the trigeminal ganglia during acute infection, mouse mortality, or the rate of reactivation from explanted latently infected ganglia. Critically, the mutant was indistinguishable from wild-type virus for the expression of ICP0 and other lytic genes in acutely and latently infected mouse trigeminal ganglia. The latter result may be related to miR-H2 being less effective in inhibiting ICP0 expression in transfection assays than a host microRNA, miR-138, which has previously been shown to inhibit lytic gene expression in infected ganglia by targeting ICP0 mRNA. Additionally, transfected miR-138 reduced lytic gene expression in infected cells more effectively than miR-H2. While this study provides little support for the hypothesis that miR-H2 promotes latency by inhibiting ICP0 expression, the possibility remains that miR-H2 might target other genes during latency.

  6. Identification of symmetry, structure and defects of dopant Mn(II) ions in Zn(C 3H 3O 4) 2(H 2O) 2 by single crystal EPR technique

    Natarajan, B.; Mithira, S.; Sambasiva Rao, P.


    In order to understand the symmetry, structure and defects of Mn(II) impurity incorporated in diaquabis[malonato(1-)-κ 2O,O'] zinc(II), single crystal EPR studies have been carried out at X-band frequencies at room temperature. Angular variation in the three orthogonal planes shows the presence of two defects, having a relatively large and small zero-field splitting parameter ( D), with orthorhombic symmetry. The spin-Hamiltonian parameters, estimated from the three mutually orthogonal crystal rotations, are: Defect I:g xx = 1.959, g yy = 1.998, g zz = 2.011; A xx = -8.73, A yy = -8.55, A zz = -9.10 mT; D xx = 5.58, D yy = 1.33, D zz = -6.91 mT. Defect II:g xx = 2.015, g yy = 1.996, g zz = 2.004; A xx = -8.18, A yy = -8.00, A zz = -8.58 mT; D xx = 33.48, D yy = 6.92, D zz = -40.40 mT. The observed large zero-field tensor for Defect II is due to the steric effects caused by the two malonate rings. The location of the two interstitial defects has been determined from the X-ray data of the host lattice. The powder EPR spectrum also confirms the chemical inequivalence of the two defects. The optical absorption spectrum shows the characteristic of Mn(II) ions in distorted octahedral symmetry.

  7. Hydrothermal Synthesis and Structure of a Novel Molybdenum Phosphate: Na4(H3O) [Na(HPO4)2(PO4)4Mo18O49]·16H2O①


    The title compound Na5H37P6Mo18O90 1 (Mr=1658) was synthesized under hydrothermal condition and its crystal structure was determined by X-ray diffraction. It crystallized in the monoclinic system, space group P21 with a =14.957(1), b =16.535(1), c = 16.159(1)?,β=108.586(2)°, V=3787.85?3, Dc =3.040g/cm3, Z=2,μ(MoKα)=3.17mm-1, F(000)=3242. The final R and wR are 0.0500 and 0.1535 for 6643 observable reflections with I≥2σ(I), respectively. The result of structure analysis indicates that [Na(HPO4)2(PO4)4-Mo18 O49]5-anions 2 in 1 has the symmetry of C2V, in which each MoVIO6 octahedron is connected to adjacent PO4 tetrahedra through corner-sharing and to adjacent octahedra through edge-sharing or corner-sharing.

  8. Thermodynamics and crystal chemistry of rhomboclase, (H5O2)Fe(SO4)2·2H2O, and the phase (H3O)Fe(SO4)2 and implications for acid mine drainage

    Majzlan, Juraj; Grevel, Klaus Dieter; Kiefer, Boris


    The system Fe2O3-SO3-H2O contains the most important minerals of acid mine drainage (AMD), iron oxides, and iron sulfates. For geochemical modeling of the AMD systems, reliable thermodynamic data for these phases are needed. In this work, we have determined thermodynamic data for the most acidic ...

  9. Synthesis, Structure Characterization and Biological Activity of a Novel Amino Acid Salt (Hala) 8 (H3O) 10[PMo12O40]6 ·22H2O


    A novel compound was synthesized and characterized by means of elemental analysis, IR and UV spectra, TG, CV and single crystal X-ray diffraction. The compound crystallized in an orthorhombic space group C222 with a=1. 622 4(3) nm, b=3. 498 4(7) nm, c=1. 301 5(3)nm, V=7. 387(3) nm3, Z=6, R1=0. 037 3, wR2=0. 114 0. The Ala(Ala=alanine) molecules were protonated at the amino nitrogen N (1) and the C (2) of Ala group with the terminal oxygen atom O(15), O(14), O(26) and O(27) of the polyoxometalates participating in the hydrogen bond network. The anti-tumor activity of the title compound was estimated against Hela and Pc-3m cancer cells.

  10. Dynamic Deuterium Enrichment in Cometary Water via Eley–Rideal Reactions

    Yao, Yunxi; Giapis, Konstantinos P.


    The deuterium-to-hydrogen ratio (D/H) in water found in the coma of Jupiter family comet (JFC) 67P/Churyumov–Gerasimenko was reported to be (5.3 ± 0.7) × 10‑4, the highest among comets and three times the value for other JFCs with an ocean-like ratio. This discrepancy suggests the diverse origins of JFCs and clouds the issue of the origin of Earth’s oceanic water. Here we demonstrate that Eley–Rideal reactions between accelerated water ions and deuterated cometary surface analogs can lead to instantaneous deuterium enrichment in water scattered from the surface. The reaction proceeds with H2O+ abstracting adsorbed D atoms, forming an excited H2DO* state, which dissociates subsequently to produce energetic HDO. Hydronium ions are also produced readily by the abstraction of H atoms, consistent with H3O+ detection and abundance in various comets. Experiments with water isotopologs and kinematic analysis on deuterated platinum surfaces confirmed the dynamic abstraction mechanism. The instantaneous fractionation process is independent of the surface temperature and may operate on the surface of cometary nuclei or dust grains, composed of deuterium-rich silicates and carbonaceous chondrites. The requisite energetic water ions have been detected in the coma of 67P in two populations. This dynamic fractionation process may temporarily increase the water D/H ratio, especially as the comet gets closer to the Sun. The magnitude of the effect depends on the water ion energy-flux and the deuterium content of the exposed cometary surfaces.

  11. Toward a unified picture of the water self-ions at the air-water interface: a density functional theory perspective.

    Baer, Marcel D; Kuo, I-Feng W; Tobias, Douglas J; Mundy, Christopher J


    The propensities of the water self-ions, H3O(+) and OH(-), for the air-water interface have implications for interfacial acid-base chemistry. Despite numerous experimental and computational studies, no consensus has been reached on the question of whether or not H3O(+) and/or OH(-) prefer to be at the water surface or in the bulk. Here we report a molecular dynamics simulation study of the bulk vs interfacial behavior of H3O(+) and OH(-) that employs forces derived from density functional theory with a generalized gradient approximation exchange-correlation functional (specifically, BLYP) and empirical dispersion corrections. We computed the potential of mean force (PMF) for H3O(+) as a function of the position of the ion in the vicinity of an air-water interface. The PMF suggests that H3O(+) has equal propensity for the interface and the bulk. We compare the PMF for H3O(+) to our previously computed PMF for OH(-) adsorption, which contains a shallow minimum at the interface, and we explore how differences in solvation of each ion at the interface vs in the bulk are connected with interfacial propensity. We find that the solvation shell of H3O(+) is only slightly dependent on its position in the water slab, while OH(-) partially desolvates as it approaches the interface, and we examine how this difference in solvation behavior is manifested in the electronic structure and chemistry of the two ions.

  12. H3O2-, O22- and O2•- bridging ligands in cobalt(III) complexes of an acyclic phenolate-hinged dinucleating ligand

    Ghiladi, Morten; Gomez, Jonnes T.; Hazell, A.


    The dicobalt(III) complex, [Co2(bpbp)(μ-H3O2)2](ClO4)3 (bpbp− = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-tert-butylphenolate), obtained by reaction of cobalt(II) perchlorate with Hbpbp under ambient conditions contains two μ-H3O2− bridging ligands. The H-bonded O⋯O distances in this motif are 2...

  13. Characterisation of the rare cadmium chromate pigment in a 19th century tube colour by Raman, FTIR, X-ray and EPR

    Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana


    chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour “Jaune de Cadmium Citron”. The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO4·KOH·H2O or more accurately as KCd2(CrO4)2(H3O2) illustrating the μ-H3O2– species...

  14. Dissociative photoionization of ethyl acrylate: Theoretical and experimental insights

    Song, Yanlin; Chen, Jun; Ding, Mengmeng; Wei, Bin; Cao, Maoqi; Shan, Xiaobin; Zhao, Yujie; Huang, Chaoqun; Sheng, Liusi; Liu, Fuyi


    The photoionization and dissociation of ethyl acrylate have been investigated by time-of-flight mass spectrometer with tunable vacuum ultraviolet (VUV) source in the range of 9.0-20.0 eV. The photoionization mass spectrum (PIMS) for ethyl acrylate and photoionization efficiency (PIE) curves for its major fragment ions: C5H7O2+, C4H5O2+, C3H5O2+, C3H4O+, C3H3O+, C2H5O+, C2H3O+, C2H5+ and C2H4+ have been obtained. The formation channels of main fragments are predicted by Gaussian 09 program at G3B3 level and examined via their dissociation energies from experimental results. Based on our analysis, nine main dissociative photoionization channels are proposed: C5H7O2+ + H, C4H5O2+ + CH3, C3H5O2+ + C2H3, C3H4O+ + C2H4O, C3H3O+ + C2H5O, C2H5O+ + C3H3O, C2H3O+ + C3H5O, C2H5+ + C3H3O2, C2H4+ + C3H4O2, respectively. The results of this work lead to a better understanding of photochemistry in the environment.

  15. Analysis of reaction rates of single molecules on metal surfaces

    Ueba, H.


    The experimental results of the action spectra i.e., reaction rate R(V) as a function of a bias voltage V are analyzed for rotation of a single CCH (D) molecule on a Cu (100) surface [5] and hopping of a single H(D)2O molecule on Pd(111) surface [6]. In the former system it is identified that rotation occurs if enough energy stored in the C-H (D) in-plane bending (IPB) mode excited by tunneling electron is transferred to the C-H (D) out of plane bending (OPB) mode (reaction coordinate mode) via the anharmonic mode coupling in a single electron process. The calculated R(V) shows an excellent agreement with the experimental results except at the low bias voltages below V ≃ 60 mV where no experimental data is available for the nonlinear current I dependence of R(I). A reproduction of the experimental R(V) at the higher voltage region allows us to determine the vibrational density of states of the C-H IPB mode and its coupling rate to the C-H (D) OPB mode as well as the inelastic tunneling current to excite IPB mode. A change of a conductance upon excitation of the C-H IPB mode enables us to evaluate the electron-vibration coupling strength inducing the rotation motion of CCH molecule. In the latter system investigated at a high temperature of about 40 K, the constant R(V) due to thermal hopping followed by the rapid increase is satisfactory explained by anharmonic inter-mode coupling between the scissor mode excited by tunneling electrons and the frustrated translation mode for H(D)2O molecule on Pd(111).

  16. Ion chemistry in the coma of comet 67P near perihelion

    Fuselier, S. A.; Altwegg, K.; Balsiger, H.; Berthelier, J. J.; Beth, A.; Bieler, A.; Briois, C.; Broiles, T. W.; Burch, J. L.; Calmonte, U.; Cessateur, G.; Combi, M.; De Keyser, J.; Fiethe, B.; Galand, M.; Gasc, S.; Gombosi, T. I.; Gunell, H.; Hansen, K. C.; Hässig, M.; Heritier, K. L.; Korth, A.; Le Roy, L.; Luspay-Kuti, A.; Mall, U.; Mandt, K. E.; Petrinec, S. M.; Rème, H.; Rinaldi, M.; Rubin, M.; Sémon, T.; Trattner, K. J.; Tzou, C.-Y.; Vigren, E.; Waite, J. H.; Wurz, P.


    The coma and the comet-solar wind interaction of comet 67P/Churyumov-Gerasimenko changed dramatically from the initial Rosetta spacecraft encounter in 2014 August through perihelion in 2015 August. Just before equinox (at 1.6 au from the Sun), the solar wind signal disappeared and two regions of different cometary ion characteristics were observed. These `outer' and `inner' regions have cometary ion characteristics similar to outside and inside the ion pileup region observed during the Giotto approach to comet 1P/Halley. Rosetta/Double-Focusing Mass Spectrometer ion mass spectrometer observations are used here to investigate the H3O+/H2O+ ratio in the outer and inner regions at 67P/ Churyumov-Gerasimenko. The H3O+/H2O+ ratio and the H3O+ signal are observed to increase in the transition from the outer to the inner region and the H3O+ signal appears to be weakly correlated with cometary ion energy. These ion composition changes are similar to the ones observed during the 1P/Halley flyby. Modelling is used to determine the importance of neutral composition and transport of neutrals and ions away from the nucleus. This modelling demonstrates that changes in the H3O+/H2O+ ratio appear to be driven largely by transport properties and only weakly by neutral composition in the coma.

  17. Autoionization of water: does it really occur?

    Artemov, V G; Sysoev, N N; Volkov, A A


    The ionization constant of water Kw is currently determined on the proton conductivity sigma1 which is measured at frequencies lower than 10^7 Hz. Here, we develop the idea that the high frequency conductivity sigma2 (~10^11 Hz), rather than sigma1 represents a net proton dynamics in water, to evaluate the actual concentration c of H3O+ and OH- ions from sigma2. We find c to be not dependent on temperature to conclude that i) water electrodynamics is due to a proton exchange between H3O+ (or OH-) ions and neutral H2O molecules rather than spontaneous ionization of H2O molecules, ii) the common Kw (or pH) reflects the thermoactivation of the H3O+ and OH- ions from the potential of their interaction, iii) the lifetime of a target water molecule does not exceed parts of nanosecond.

  18. Permethyl Yttrocene 2-Furyl Complexes : Synthesis and Ring-Opening Reactions of the Furyl Moiety

    Ringelberg, Stéphanie N.; Meetsma, Auke; Troyanov, Sergei I.; Hessen, Bart; Teuben, Jan H.


    Permethyl yttrocene 2-furyl ate-complexes Cp*2Y(μ-C4H3O)(μ-Cl)Li(THF)2 (1, Cp* = C5-Me5) and Cp*2Y(μ-C4H3O)2Li(TMEDA) (2) were obtained by reaction of Cp*2Y(μ-Cl)2Li(OEt2)2 with 1 and 2 equiv of 2-lithiofuran, respectively. Furan is metalated by (Cp*2YH)2 in hydrocarbon solvents to give the 2-furyl

  19. Hydroxonium 1-ammonioethane-1,1-diyldiphosphonate

    Ming Li


    Full Text Available The title complex, H3O+·NH3C(CH3(PO3H2−, contains a hydroxonium ion and an NH3C(CH3(PO3H2− anion. The three H atoms of H3O+ form a pseudo-tetrahedron by being distributed over four positions with occupation factors of 0.75. Multiple N—H...O and O—H...O hydrogen bonds in the crystal structure form an intricate three-dimensional supramolecular network.

  20. Determination and Quantification of the Local Environments in Stoichiometric and Defect Jarosite by Solid-State 2H NMR Spectroscopy

    Nielsen, Ulla Gro; Grey, Clare P.; Majzlan, Juraj


    -bonded to nearby sulfate 0 atoms, with a (Fe)OD-O(S) distance of 2.79(4) angstrom. No evidence for the intrinsic protonation reaction Fe2OH + H3O+ -> Fe2OH2 + H2O is found in the hydronium jarosite, suggesting that this mechanism is not the cause of the anomalous magnetic behavior of this material. The results...

  1. Drug: D01779 [KEGG MEDICUS

    Full Text Available hydrate; Sodium acetate (TN) C2H3O2. 3H2O. Na 136.0348 136.0796 D01779.gif Pharmaceutic aid [in dialysis solutions... ADDITIVES B05XA Electrolyte solutions B05XA08 Sodium acetate D01779 Sodium acetate hydrate (JP16); Sodium a

  2. atmospheric volatile organic compounds

    A. R. Koss


    organic compounds (VOCs that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument. Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1 NO+ is useful for isomerically resolved measurements of carbonyl species; (2 NO+ can achieve sensitive detection of small (C4–C8 branched alkanes but is not unambiguous for most; and (3 compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12–C15 n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.

  3. Evaluation of NO+ reagent ion chemistry for online measurements of atmospheric volatile organic compounds

    Koss, Abigail R.; Warneke, Carsten; Yuan, Bin; Coggon, Matthew M.; Veres, Patrick R.; de Gouw, Joost A.


    NO+ chemical ionization mass spectrometry (NO+ CIMS) can achieve fast (1 Hz and faster) online measurement of trace atmospheric volatile organic compounds (VOCs) that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument). Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC) interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1) NO+ is useful for isomerically resolved measurements of carbonyl species; (2) NO+ can achieve sensitive detection of small (C4-C8) branched alkanes but is not unambiguous for most; and (3) compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12-C15) n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.


    The speciation of aqueous free chlorine above pH 5 is a well-understood equilibrium of H2O + HOCl (equilibrium) OCl- + H3O+ with a pKa of 7.5. However, the identity of another very potent oxidant present at low pH (below 5) has been attributed by some researchers to Cl2 (aq), a...

  5. Drug: D00931 [KEGG MEDICUS

    Full Text Available 1.gif Pharmaceutic aid [buffering agent] ATC code: A12AA12 Anatomical Therapeutic Chemical (ATC) classificat...D00931 Drug Calcium acetate (USP); Phoslo (TN) (C2H3O2)2. Ca 157.9892 158.166 D0093

  6. Heterometallic aluminates: alkali metals trapped by an aluminium aryloxide claw.

    Muñoz, M Teresa; Cuenca, Tomás; Mosquera, Marta E G


    A series of heterometallic aluminium-alkali metal species [AlMMe2{2,6-(MeO)2C6H3O}2]n have been isolated for lithium, sodium and potassium. These compounds can be generated by the reaction of [AlMe2{2,6-(MeO)2C6H3O}]2 with the metallated phenol [M{2,6-(MeO)2C6H3O}]n or through the reaction of the mixture of AlMe3 and the appropriate alkali metal alkyl base with two equivalents of 2,6-dimethoxyphenol. In the heterometallic species obtained, the {AlMe2{2,6-(MeO)2C6H3O}2}(-) moiety is observed and could be described as a claw which fixes the alkali ion by the phenoxide oxygen atoms while the methoxy groups help to stabilize their coordination sphere. All compounds have been characterized by NMR spectroscopy and X-ray diffraction methods. Catalytic studies reveal that these compounds are active in ring-opening polymerization of L-lactide.

  7. Cyclo- and carbophosphazene-supported ligands for the assembly of heterometallic (Cu2+/Ca2+, Cu2+/Dy3+, Cu2+/Tb3+) complexes: synthesis, structure, and magnetism.

    Chandrasekhar, Vadapalli; Senapati, Tapas; Dey, Atanu; Das, Sourav; Kalisz, Marguerite; Clérac, Rodolphe


    The carbophosphazene and cyclophosphazene hydrazides, [{NC(N(CH(3))(2))}(2){NP{N(CH(3))NH(2)}(2)}] (1) and [N(3)P(3)(O(2)C(12)H(8))(2){N(CH(3))NH(2)}(2)] were condensed with o-vanillin to afford the multisite coordination ligands [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-OH)(m-OCH(3))}(2)}] (2) and [{N(2)P(2)(O(2)C(12)H(8))(2)}{NP{N(CH(3))N═CH-C (6)H(3)-(o-OH)(m-OCH(3))}(2)}] (3), respectively. These ligands were used for the preparation of heterometallic complexes [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuCa(NO(3))(2)}] (4), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{Cu(2)Ca(2)(NO(3))(4)}]·4H(2)O (5), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(4)}]·CH(3)COCH(3) (6), [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(3)}] (7), and [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuTb(NO(3))(3)}] (8). The molecular structures of these compounds reveals that the ligands 2 and 3 possess dual coordination pockets which are used to specifically bind the transition metal ion and the alkaline earth/lanthanide metal ion; the Cu(2+)/Ca(2+), Cu(2+)/Tb(3+), and Cu(2+)/Dy(3+) pairs in these compounds are brought together by phenoxide and methoxy oxygen atoms. While 4, 6, 7, and 8 are dinuclear complexes, 5 is a tetranuclear complex. Detailed magnetic properties on 6-8 reveal that these compounds show weak couplings between the magnetic centers and magnetic anisotropy. However, the ac susceptibility experiments did not reveal any out of phase signal suggesting that in these compounds slow relaxation of magnetization is absent above 1.8 K.

  8. Amorphous and polycrystalline water ices in space environments

    Andrade, Diana; Pilling, Sergio; Da Silveira, Enio; Barros, Ana


    Ices are an important reservoir of more complex molecular species in several space environments, containing information about the composition and formation of these regions. Water ice is the dominant constituent of interstellar ices in most lines of sight and is about 70 % of the composition in comets, being a key molecule in astrochemical models. It is believed that one of the reactive species possibly evaporated from the water ices is the hydronium ion, H_{3}O^{+}, which plays an important role in the oxygen chemistry network. This ion has been detected in the lunar surface of Enceladus and Titan, and toward the Sagittarius B2 molecular Clouds, where H_{2}O and OH were also identified. In this work, the ion desorption due to radiolysis in ices constituted by water at three different temperatures (40, 70 and 125 K) is studied, to investigate the different allotropic water ices. A discussion on the rate of H_{3}O^{+} and water delivered to gas phase, as well as the half-life of water ice grains, inside dense molecular clouds considering a constants cosmic ray flux is given. The ions desorbed from water ice have been mass/charge analyzed by a time-of-flight spectrometer. Among the results, it is seen that in the positive ion spectrum of high density amorphous water ice at 40 K the highest desorption yields (ejected ions/impact) correspond to H^{+}, H_{3}O^{+} and clusters formed by (H_{2}O)_{n}R^{+}, where R^{+} is H_{3}O^{+} and 1 ≤ n ≤ 25. At T = 125 K, the ice is in its low density polycrystalline form and new clusters are present, such as (H_{2}O)_{n}R^{+}, where R^{+} is H_{2}^{+} and H_{3}^{+} (for low n), beyond H_{3}O^{+}. Therefore, it is seen that (H_{2}O)_{n}H_{3}O^{+} series (with n between 1 and 25) is dominant in all cases. The H_{3}O^{+} desorption yield at 40 K is about 5times10^{-3} ions/impact. This value is 4-5 times higher than the one obtained at T > 125 K. This behavior is also seen to all series member and consequently to the sum (Yn).

  9. Towards a unified picture of the water self-ions at the air-water interface: a density functional theory perspective

    Baer, Marcel D.; Kuo, I-F W.; Tobias, Douglas J.; Mundy, Christopher J.


    The propensities of the water self ions, H3O+ and OH- , for the air-water interface has implications for interfacial acid-base chemistry. Despite numerous experimental and computational studies, no consensus has been reached on the question of whether or not H3O+ and/or OH- prefer to be at the water surface or in the bulk. Here we report a molecular dynamics simulation study of the bulk vs. interfacial behavior of H3O+ and OH- that employs forces derived from density functional theory with a generalized gradient approximation exchangecorrelation functional (specifically, BLYP) and empirical dispersion corrections. We computed the potential of mean force (PMF) for H3O+ as a function of the position of the ion in a 215-molecule water slab. The PMF is flat, suggesting that H3O+ has equal propensity for the air-water interface and the bulk. We compare the PMF for H3O+ to our previously computed PMF for OH- adsorption, which contains a shallow minimum at the interface, and we explore how differences in solvation of each ion at the interface vs. the bulk are connected with interfacial propensity. We find that the solvation shell of H3O+ is only slightly dependent on its position in the water slab, while OH- partially desolvates as it approaches the interface, and we examine how this difference in solvation behavior is manifested in the electronic structure and chemistry of the two ions. DJT was supported by National Science Foundation grant CHE-0909227. CJM was supported by the U.S. Department of Energy‘s (DOE) Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the Department of Energy by Battelle. The potential of mean force required resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DEAC05-00OR22725. The remaining simulations

  10. Discussion about the Value of Dissociation Equilibrium Constant Ka of Water%关于H2O的离解平衡常数Ka值的探讨

    胡乃非; 林树昌



  11. Is the Beckmann rearrangement a concerted or stepwise reaction? A computational study.

    Yamabe, Shinichi; Tsuchida, Noriko; Yamazaki, Shoko


    [reaction: see text] RB3LYP calculations were performed on the Beckman rearrangement by the use of three substrates, acetone oxime (1), acetophenone oxime (2), and cyclohexanone oxime (3). Acidic solvents were modeled by H+ (CH3COOH)3 and H3O+ (H2O)6, and reaction paths were determined precisely. For 1, a two-step process involving a sigma-type cationic complex was obtained. For 2, a three-step process with pi- and sigma-type complexes was found in H+ (CH3COOH)3 and a two-step process involving a sigma-type cationic complex was obtained in H3O+ (H2O)6. However, for 3, a concerted process without pi and sigma complexes was calculated, which leads to the product, epsilon-caprolactam. Three different mechanisms were explained in terms of FMO theory.

  12. Synthesis and Structures of New Cyclopalladated Ferrocenylimines


    The new complexes, [PdCl{C5H4FeC5H4CHRN=CHC4H3O}(Ph3P)] (R= H, CH3) were synthesized via two novel Schiff bases (C5H5FeC5H4CHRN=CHC4H3O, R= H, CH3) with lithium tetrachloropalladate (Ⅱ), and characterized by IR, elemental analysis, 1H NMR. Complex 5a was further determined by X-ray single crystal diffraction. We found that it contained an intramolecular N→Pd coordination in the compound Sa, and the palladium atom was bound to the unsubstituted Cp ring. The Pd-N, Pd-C (1) and Pd-O bond lengths were 2.121 (3), 2.008 (4) and 2.990 (A), respectively.

  13. Photoionization and fragmentation of H3O+ under XUV irradiation

    Domesle, C.; Dziarzhytski, S.; Guerassimova, N.;


    ++H+ (72±4%), OH0+2H+ (18±6%), and OH++H++H0 (10±1%). A kinematic analysis of the H2O++H+ channel after photoabsorption at 35.56 nm (where only outer valence ionization is possible) showed dissociation into excited states of the water radical ion, where the 1A1 state breaks up into the linear à 2A1 state...... was performed at 21.85 nm, where both inner and outer valence ionization are allowed, and revealed that the XUV photolysis of H3O+ is by far dominated by ionization of outer valence electrons forming the 1A1 and 2E states of the dication H3O2+. The dications were found to dissociate into the channels H2O...

  14. Crystal structure of bis-(1-ethyl-pyridinium) dioxonium hexa-cyanidoferrate(II).

    Tanaka, Rikako; Matsushita, Nobuyuki


    The title compound, (C7H10N)2(H3O)2[Fe(CN)6] or (Etpy)2(H3O)2[Fe(CN)6] (Etpy(+) is 1-ethyl-pyridinium), crystallizes in the space group Pnnm. The Fe(II) atom of the [Fe(CN)6](4-) anion lies on a site with site symmetry ..2/m, and has an octa-hedral coordination sphere defined by six cyanido ligands. Both the Etpy(+) and the oxonium cations are located on a mirror plane. In the crystal, electron-donor anions of [Fe(CN)6](4-) and electron-acceptor cations of Etpy(+) are each stacked parallel to the b axis, resulting in a columnar structure with segregated moieties. The crystal packing is stabilized by a three-dimensional O-H⋯N hydrogen-bonding network between the oxonium ions and the cyanide ligands of [Fe(CN)6](4-).

  15. Stacking of benzene with metal chelates: calculated CCSD(T)/CBS interaction energies and potential-energy curves.

    Malenov, Dušan P; Ninković, Dragan B; Sredojević, Dušan N; Zarić, Snežana D


    Accurate values for the energies of stacking interactions of nickel- and copper-based six-membered chelate rings with benzene are calculated at the CCSD(T)/CBS level. The results show that calculations made at the ωB97xD/def2-TZVP level are in excellent agreement with CCSD(T)/CBS values. The energies of [Cu(C3H3O2)(HCO2)] and [Ni(C3H3O2)(HCO2)] chelates stacking with benzene are -6.39 and -4.77 kcal mol(-1), respectively. Understanding these interactions might be important for materials with properties that are dependent on stacking interactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Crystal structure of bis(1-ethylpyridinium dioxonium hexacyanidoferrate(II

    Rikako Tanaka


    Full Text Available The title compound, (C7H10N2(H3O2[Fe(CN6] or (Etpy2(H3O2[Fe(CN6] (Etpy+ is 1-ethylpyridinium, crystallizes in the space group Pnnm. The FeII atom of the [Fe(CN6]4− anion lies on a site with site symmetry ..2/m, and has an octahedral coordination sphere defined by six cyanido ligands. Both the Etpy+ and the oxonium cations are located on a mirror plane. In the crystal, electron-donor anions of [Fe(CN6]4− and electron-acceptor cations of Etpy+ are each stacked parallel to the b axis, resulting in a columnar structure with segregated moieties. The crystal packing is stabilized by a three-dimensional O—H...N hydrogen-bonding network between the oxonium ions and the cyanide ligands of [Fe(CN6]4−.

  17. Protolytic equilibria of bromazepam



    Full Text Available The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0–14 at 25 ?C and at ionic strength of 0.1 mol/dm3 (NaCl. On the basis of 13C-NMR spectra, the protonation site was predicted – in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pKa1 2.83 and pKa2 11.60 and potentiometrically (pKa1 2.99. In the heterogeneous system the following equilibrium constants were determined: Ks0 = [HA] (pKs0 3.44, Ks1 = [H2A+]/[H3O+] (pKs1 0.61, and Ks2 = [A-][H3O+] (pKs2 15.04.

  18. Single crystal X-ray structure of the artists’ pigment zinc yellow

    Simonsen, Kim Pilkjær; Christiansen, Marie Bitsch; Vinum, Morten Gotthold


    The artists’ pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hithert...... determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2 − moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type....

  19. Drug: D08134 [KEGG MEDICUS

    Full Text Available D08134 Drug Lithium acetate; Quilonorm (TN) C2H3O2. Li 66.0293 65.985 D08134.gif An...YSTEM N05 PSYCHOLEPTICS N05A ANTIPSYCHOTICS N05AN Lithium N05AN01 Lithium D08134 Lithium acetate USP drug cl...assification [BR:br08302] Bipolar Agents Mood Stabilizers Lithium D08134 Lithium

  20. Lewis acid fragmentation of a lithium aryloxide cage: generation of new heterometallic aluminium-lithium species.

    Muñoz, Ma Teresa; Urbaneja, Carmen; Temprado, Manuel; Mosquera, Marta E G; Cuenca, Tomás


    Heterometallic aluminium-lithium species were prepared by the fragmentation reaction of the hexametallic cage compound [Li{2,6-(MeO)(2)C(6)H(3)O}](6) (1) with alkyl aluminium derivatives. Depending on the aluminium precursor, the species formed present different nuclearities in the solid state as shown by single crystal X-ray analysis. Spectroscopic and computational studies have been performed to study the nuclearity of the synthesized compounds in solution.

  1. Unipolar Electric Machines with Liquid-Metal Current Pickup,


    A new homopolar motor , e4ournal of the Franklin Institute*. 1954, v. 258, Ne 1. %4 144093, Bjo.1.leTeJb H3o6peTeHxA. 1962,. 14 1. 30. X oao p o a...VIII. Motor Mode of Unipolar Electrical Machine ............... 301 Chapter IX. Bases of Theory and Calculation of Nonpolar Dynamos without...unipolar electric motors . Are examined questions of the classification of acyclic machines, their electromagnetic field, calculation of magnetic circuit

  2. 2-(2-Hydroxyphenyl-4,5-dimethyl-1H-imidazol-3-ium acetate monohydrate

    Chong-Bo Liu


    Full Text Available In the title compound, C11H13N2O+·C2H3O2−·H2O, the dihedral angle between the benzene ring and the imidazole ring is 7.83 (6°. In the crystal structure, N—H...O and O—H...O hydrogen bonds form a two-dimensional network. All the methyl H atoms are disorderd over two sites with equal occupancies.

  3. Synthesis and Crystal Structure of Macrocyclic Cavitand Cucurbit[5]uril and Its Supramolecular Adduct with Cu(Ⅱ)

    LIU,Si-Min(刘思敏); HUANG,Zi-Xiang(黄子祥); WU,Xiao-Jun(吴晓军); LIANG,Feng(梁峰); WU,Cheng-Tai(吴成泰)


    The first supramolecular adduct (H3O)2[Cu(H2O)4](SO4)2·2(C30H30N20O10)·24(H2O) based on cucurbit[5]uril was synthesized and characterized by single crystal X-ray diffraction analysis. In the adduct, copper ion is coordinated by four oxygen atoms from H2O. The latter links two cucurbit[5]uril molecules due to a complicated hydrogen bonding containing lattice water molecules.

  4. Synthesis and characterization of acrylate-bridged dinuclear copper complex and acetate and 2,4,6-trimethylpyridine copper complex%Cu(Ⅱ))的丙烯酸桥联双核配合物及醋酸、2,4,6-三甲基吡啶三元配合物的合成与表征

    钱永; 王建军


    在温和条件下合成了Cu(Ⅱ)的丙烯酸双核配合物[Cu2(C3H3O2)4].H2O和醋酸、2,4,6-三甲基吡啶三元配合物[Cu(C2H3O2)2(C8H11N)2]。通过元素分析、红外光谱、紫外光谱和核磁测试表征了该两种配合物的组成和结构,并用溶解度、电导率测试等物理化学手段对配合物的物理化学性质进行了初步研究。%The acrylate-bridged dinuclear copper complex [Cu2(C3H3O2)4]·H2O and acetate and 2,4,6-Trimethylpyridine copper complex [Cu(C2H3O2)2(C8H11N)2] were synthesized under tender conditions in this paper.The elemental components and structures of the two complexes were characterized and confirmed by elemental analyses,FT-IR,UV-Vis and 1H NMR.And the primary investigation on the physical and chemical characteristics of the two complexes has been carried out through some physical and chemical methods such as the solubility and molar conductivity in this work.

  5. Selected Ion Flow-Drift Tube Mass Spectrometry: Quantification of Volatile Compounds in Air and Breath.

    Spesyvyi, Anatolii; Smith, David; Španěl, Patrik


    A selected ion flow-drift tube mass spectrometric analytical technique, SIFDT-MS, is described that extends the established selected ion flow tube mass spectrometry, SIFT-MS, by the inclusion of a static but variable E-field along the axis of the flow tube reactor in which the analytical ion-molecule chemistry occurs. The ion axial speed is increased in proportion to the reduced field strength E/N (N is the carrier gas number density), and the residence/reaction time, t, which is measured by Hadamard transform multiplexing, is correspondingly reduced. To ensure a proper understanding of the physics and ion chemistry underlying SIFDT-MS, ion diffusive loss to the walls of the flow-drift tube and the mobility of injected H3O(+) ions have been studied as a function of E/N. It is seen that the derived diffusion coefficient and mobility of H3O(+) ions are consistent with those previously reported. The rate coefficient has been determined at elevated E/N for the association reaction of the H3O(+) reagent ions with H2O molecules, which is the first step in the production of H3O(+)(H2O)1,2,3 reagent hydrate ions. The production of hydrated analyte ion was also experimentally investigated. The analytical performance of SIFDT-MS is demonstrated by the quantification of acetone and isoprene in exhaled breath. Finally, the essential features of SIFDT-MS and SIFT-MS are compared, notably pointing out that a much lower speed of the flow-drive pump is required for SIFDT-MS, which facilitates the development of smaller cost-effective analytical instruments for real time breath and fluid headspace analyses.

  6. Hot, metastable hydronium ion in the Galactic centre: formation pumping in X-ray-irradiated gas?

    Lis, Dariusz C; Schilke, Peter; Bergin, Edwin A; Emprechtinger, Martin


    With a 3.5 m diameter telescope passively cooled to approximately 80 K, and a science payload comprising two direct detection cameras/medium resolution imaging spectrometers (PACS and SPIRE) and a very high spectral resolution heterodyne spectrometer (HIFI), the Herschel Space Observatory is providing extraordinary observational opportunities in the 55-670 μm spectral range. HIFI has opened for the first time to high-resolution spectroscopy the submillimetre band that includes the fundamental rotational transitions of interstellar hydrides, the basic building blocks of astrochemistry. We discuss a recent HIFI discovery of metastable rotational transitions of the hydronium ion (protonated water, H(3)O(+)), with rotational level energies up to 1200 K above the ground state, in absorption towards Sagittarius B2(N) in the Galactic centre. Hydronium is an important molecular ion in the oxygen chemical network. Earlier HIFI observations have indicated a general deficiency of H(3)O(+) in the diffuse gas in the Galactic disc. The presence of hot H(3)O(+) towards Sagittarius B2(N) thus appears to be related to the unique physical conditions in the central molecular zone, manifested, for example, by the widespread presence of abundant H(3)(+). One intriguing theory for the high rotational temperature characterizing the population of the H(3)O(+) metastable levels may be formation pumping in molecular gas irradiated by X-rays emitted by the Galactic centre black hole. Alternatively, the pervasive presence of enhanced turbulence in the central molecular zone may give rise to shocks in the lower-density medium that is exposed to energetic radiation.

  7. Hydrogen-bonded sheets in benzylmethylammonium hydrogen maleate.

    Santacruz, Lynay; Abonia, Rodrigo; Cobo, Justo; Low, John N; Glidewell, Christopher


    In the title compound, C(8)H(12)N(+).C(4)H(3)O(4)(-), there is a short and almost linear but asymmetric O-H...O hydrogen bond in the anion. The ions are linked into C(2)(2)(6) chains by two short and nearly linear N-H...O hydrogen bonds and the chains are further weakly linked into sheets by a single C-H...O hydrogen bond.

  8. Modeling the effect of water activity and storage temperature on chemical stability of coffee brews.

    Manzocco, Lara; Nicoli, Maria Cristina


    This work was addressed to study the chemical stability of coffee brew derivatives as a function of water activity (aw) and storage temperature. To this purpose, coffee brew was freeze-dried, equilibrated at increasing aw values, and stored for up to 10 months at different temperatures from -30 to 60 degrees C. The chemical stability of the samples was assessed by measuring H3O+ formation during storage. Independently of storage temperature, the rate of H3O+ formation was considerably low only when aw was reduced below 0.5 (94% w/w). Beyond this critical boundary, the rate increased, reaching a maximum value at ca. 0.8 aw (78% w/w). Further hydration up to the aw of the freshly prepared beverage significantly increased chemical stability. It was suggested that mechanisms other than lactones' hydrolysis, probably related to nonenzymatic browning pathways, could contribute to the observed increase in acidity during coffee staling. The temperature dependence of H3O+ formation was well-described by the Arrhenius equation in the entire aw range considered. However, aw affected the apparent activation energy and frequency factor. These effects were described by simple equations that were used to set up a modified Arrhenius equation. This model was validated by comparing experimental values, not used to generate the model, with those estimated by the model itself. The model allowed efficient prediction of the chemical stability of coffee derivatives on the basis of only the aw value and storage temperature.

  9. The chemistry of interstellar HnO+ beyond the Galaxy

    van der Tak, Floris


    The astrochemistry of the HnO+ (n=1..3) ions is important as the main gas-phase formation route for water, and as tracer of the interstellar ionization rate by cosmic rays and other processes. While interstellar H3O+ has been known since the early 1990's, interstellar OH+ and H2O+ have only recently been detected using the Herschel space observatory and also from the ground. This paper reviews detections of HnO+ toward external galaxies and compares with ground-based work. The similarities and differences of the HnO+ chemistry within the Galaxy and beyond are discussed. Special attention is given to the low H2O/H3O+ ratio in M82 of only 3.3, suggesting rapid H2O photodissociation, and the high apparent OH+ and H2O+ abundances in Mrk 231, suggesting radiative excitation and/or formation pumping. Photodissociation rates for H3O+ and collisional cross-sections for OH+ and H2O+ with H, He and electrons are needed to test these interpretations.

  10. Triethylammonium salt of dimethyl diphenyldithiophosphates: Single crystal X-ray and DFT analysis



    The present work demonstrates the single crystal X-ray and DFT analysis of $ [{(2,4-CH_{3})_{2}C_{6}H_{3}O}_{2}$PS_{2}HNEt_{3}]$ (1) and $ [{(3,4-CH_{3})_{2}$ $C_{6}H_{3}O}_{2}$ $PS_{2}HNEt_{3}]$ (2) along with computational analysis of $ [{(3,5-CH_{3})_{2}C_{6}H_{3}O}_{2} $PS_{2}HNEt_{3}]$ (3) by using density functional theory (DFT) in its hybrid form B3LYP method. Compounds1 and 2 crystallize in the orthorhombic space group Pbca and triclinic space groupP1,respectively andtheir X-ray analysis reveals that phosphorus atom is coordinated to the two S and two O atoms to form tetrahedralgeometry. The structure is stabilized by cation–anion N–H.... S hydrogen bonded interactions. The structuralparameters, vibrational bands and energy gaps of frontier orbitals (HOMO–LUMO) have been calculated.The calculated geometric and spectral results matched the experimental data with good agreement. Theoreticallycalculated frontier molecular orbitals (HOMO–LUMO) and their energies suggest that charge transferoccurs within the compounds.

  11. Non-noble metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution

    Song, Jun-Ling; Zhang, Jian-Han; Mao, Jiang-Gao


    We reported the synthesis and crystal structures of alkali metal and alkali-earth metal phosphite, namely, CsV2(H3O)(HPO3)4 (1), and Ba3V2(HPO3)6 (2). Both compounds were prepared by hydrothermal reactions and feature unique new structures. They both exhibit 3D complicated frameworks based on VO6 octahedra which are connected by HPO3 tetrahedra via corner-sharing. Alkali or alkali earth metal cations are filled in the different channels of the frameworks. Topological analysis shows that the framework of CsV2(H3O) (HPO3)4 (1) is a new 3,3,3,4,5-connected network with the Schläfli symbol of {4.62}2{42.66.82}{63}{65.8}. The investigations of X-ray photoelectron spectroscopy (XPS) and magnetic measurement on CsV2(H3O)(HPO3)4 suggest a +3 oxidation state of the vanadium ions in compound 1. Photocatalytic performance was evaluated by photocatalytic H2 evolution and degradation of methylene blue, which shows that both compounds exhibit activity under visible-light irradiation. IR spectrum, UV-vis-NIR spectrum and thermogravimetric analysis (TGA) of compounds were also investigated.

  12. Ionization dynamics of water dimer on ice surface

    Tachikawa, Hiroto


    The solid surface provides an effective two-dimensional reaction field because the surface increases the encounter probability of bi-molecular collision reactions. Also, the solid surface stabilizes a reaction intermediate because the excess energy generated by the reaction dissipates into the bath modes of surface. The ice surface in the universe is one of the two dimensional reaction fields. However, it is still unknown how the ice surface affects to the reaction mechanism. In the present study, to elucidate the specific property of the ice surface reaction, ionization dynamics of water dimer adsorbed on the ice surface was theoretically investigated by means of direct ab-initio molecular dynamics (AIMD) method combined with ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) technique, and the result was compared with that of gas phase reaction. It was found that a proton is transferred from H2O+ to H2O within the dimer and the intermediate complex H3O+(OH) is formed in both cases. However, the dynamic features were different from each other. The reaction rate of the proton transfer on the ice surface was three times faster than that in the gas phase. The intermediate complex H3O+(OH) was easily dissociated to H3O+ and OH radical on the ice surface, and the lifetime of the complex was significantly shorter than that of gas phase (100 fs vs. infinite). The reason why the ice surface accelerates the reaction was discussed in the present study.

  13. Primary Ion Depletion Kinetics (PIDK Studies as a New Tool for Investigating Chemical Ionization Fragmentation Reactions with PTR-MS.

    Erna Schuhfried

    Full Text Available We report on a new approach for studying fragmentation channels in Proton Transfer Reaction-Mass Spectrometry (PTR-MS, which we name primary ion depletion kinetics (PIDK. PTR-MS is a chemical ionization mass spectrometric (CIMS technique deploying hydronium ions for the chemical ionization. Induced by extremely high concentrations of analyte M, depletion of the primary ions in the drift tube occurs. This is observed as quasi zero concentration of the primary ion H3O(+, and constant MH(+. Under these non-standard conditions, we find an overall changed fragmentation. We offer two explanations. Either the changed fragmentation pattern is the result of secondary proton transfer reactions. Or, alternatively, the fast depletion of H3O(+ leads to reduced heating of H3O(+ in the drift field, and consequently changed fragmentation following protonation of the analyte M. In any case, we use the observed changes in fragmentation as a successful new approach to fragmentation studies, and term it primary ion depletion kinetics, PIDK. PIDK easily yields an abundance of continuous data points with little deviation, because they are obtained in one experimental run, even for low abundant fragments. This is an advantage over traditional internal kinetic energy variation studies (electric field per number density (E/N variation studies. Also, some interpretation on the underlying fragmentation reaction mechanisms can be gleamed. We measure low occurring fragmentation (<2% of MH(+ of the compounds dimethyl sulfide, DMS, a compound that reportedly does not fragment, diethyl sulfide DES, and dipropyl sulfide DPS. And we confirm and complement the results with traditional E/N studies. Summing up, the new approach of primary ion depletion kinetics allows for the identification of dehydrogenation [MH(+ -H2] and adduct formation (RMH(+ as low abundant fragmentation channels in monosulfides.

  14. Aquaporin water channels: molecular mechanisms for human diseases.

    Agre, Peter; Kozono, David


    Although water is the major component of all biological fluids, the molecular pathways for water transport across cell membranes eluded identification until the discovery of the aquaporin family of water channels. The atomic structure of mammalian AQP1 illustrates how this family of proteins is freely permeated by water but not protons (hydronium ions, H3O+). Definition of the subcellular sites of expression predicted their physiological functions and potential clinical disorders. Analysis of several human disease states has confirmed that aquaporins are involved in multiple different illnesses including abnormalities of kidney function, loss of vision, onset of brain edema, starvation, and arsenic toxicity.

  15. Ion Irradiation of Sulfuric Acid: Implications for its Stability on Europa

    Loeffler, M. J.; Hudson, R. L.; Moore, M. H.


    The Galileo near-infrared mapping spectrometer (NIMS) detected regions on Europa's surface containing distorted H2O bands. This distortion likely indicates that there are other molecules mixed with the water ice. Based on spectral comparison, some of the leading possibilities are sulfuric acid, salts. or possibly H3O(+). Previous laboratory studies have shown that sulfuric acid can be created by irradiation of H2OSO2 mixtures, and both molecules are present on Europa. In this project, we were interested in investigating the radiation stability of sulfuric acid (H2SO4) and determining its lifetime on the surface of Europa.

  16. Poly[[[bis(acetato-κOcopper(II]-μ-1,4-diimidazol-1-ylbenzene-κ2N3:N3′] dihydrate

    Yi-Fang Deng


    Full Text Available In the title linear coordination polymer, {[Cu(C2H3O22(C12H10N4]·2H2O}n, the CuII atom is coordinated by two N atoms from two different symmetry-related 1,4-diimidazol-1-ylbenzene (dib ligands and two carboxylate O atoms from two acetate ligands in a square-planar geometry. The Cu atoms are linked by the dib ligands, forming an extended chain. These chains are linked by O—H...O hydrogen bonds into a three-dimensional supramolecular network. The CuII atom lies on a center of inversion.

  17. Mechanism of the Thermal Decomposition of Furan

    Vasiliou, Angayle; Ellison, G. Barney; Nimlos, Mark R.; Daily, John W.


    Both furan (C_4H_4O) and furfural (C_4H_3O-CHO) areimportant products in biomass pyrolysis. We have used a resistively-heated SiC tubular reactor with a 30 microseconds residence time to study the thermal cracking of furan. The decomposition products are identified by two independent techniques: 118.2 nm VUV photoionization mass spectroscopy and infrared spectroscopy. We observe three different thermal dissociation channels leading to: a) CH_3CCH + CO b) HCCH + CH_2CO c) HCCCH_2.

  18. Point Defects in Double Helix Induced by Interaction of Silver Nanoparticles with DNA

    Bregadze, Vasil G; Giorgadze, Tamar G; Monaselidze, Jamlet R; Jaliashvili, Zaza V; Khuskivadze, Temur B


    Interaction of DNA-silver nanoparticles (AgNPs) complexes with H3O+, Cu2+ and Cl- has been studied by spectro-photometric, spectro-fluorimetric and differential scanning micro calorimetric methods. It is shown that DNA is a catalyst in redox reactions taking place in AgNPs adsorbed on its surface. We also demonstrate that Ag+ ions that are freed after corrosion of nanoparticles show absorption into the inner part of DNA double helix, i.e. they make the so-called cross-links between complementary base pairs of DNA. The cross-links present point defects of DNA which leads in-vivo to cell death.

  19. Enhancing proton conduction in 2D Co-La coordination frameworks by solid-state phase transition.

    Bao, Song-Song; Otsubo, Kazuya; Taylor, Jared M; Jiang, Zheng; Zheng, Li-Min; Kitagawa, Hiroshi


    We report that a new 2D 3d-4f phosphonate [Co(III)La(III)(notpH)(H2O)6]ClO4·5H2O (CoLa-II) can undergo a phase transition above 45 °C and 93% relative humidity, resulting in [H3O][CoLa(notp)(H2O)4]ClO4·3H2O (CoLa-III). The transition is accompanied by the release of the proton from intralayer to interlayer, and thus the proton conductivity of the material is increased by 1 order of magnitude.

  20. Effects of Turbidity on Fluridone Treatments for Curlyleaf Pondweed Control


    sodium and metal halide bulbs. Curlyleaf pondweed turions were obtained from Eau Galle Reservoir, WI, and sprouted in the growth chamber under...CaCO3] and dolomite [CaMg(CO3)2] present. Expandable clays, such as kaolinite [Al2Si2O5(OH)4], illite [(K,H3O)Al2Si3 ALO10(OH)2], and chlorite [(Mg,Fe...kaolinite, illite, and chlorite present only in small amounts. Water column pH also affects fluridone adsorption to clays. Because fluridone is weakly

  1. Diammonium diaqua­bis(malonato-κ2 O,O′)cobaltate(II) dihydrate

    Xu, Haiyun; Wang, Fengwu


    The title complex, (NH4)2[Co(C3H3O4)2(H2O)2]·2H2O, features a six-coordinate Co atom located on a center of symmetry. The octa­hedral O6 coordination geometry is defined by two bidentate malonate ligands and two water mol­ecules, with the latter in a trans configuration. The mol­ecules are linked through O—H⋯O and N—H⋯O hydrogen-bonding inter­actions, forming a three-dimensional supra­molecular network. PMID:21201875

  2. Diammonium diaquabis(malonato-κ2O,O′cobaltate(II dihydrate

    Fengwu Wang


    Full Text Available The title complex, (NH42[Co(C3H3O42(H2O2]·2H2O, features a six-coordinate Co atom located on a center of symmetry. The octahedral O6 coordination geometry is defined by two bidentate malonate ligands and two water molecules, with the latter in a trans configuration. The molecules are linked through O—H...O and N—H...O hydrogen-bonding interactions, forming a three-dimensional supramolecular network.

  3. Diammonium diaqua-bis(malonato-κO,O')cobaltate(II) dihydrate.

    Xu, Haiyun; Wang, Fengwu


    The title complex, (NH(4))(2)[Co(C(3)H(3)O(4))(2)(H(2)O)(2)]·2H(2)O, features a six-coordinate Co atom located on a center of symmetry. The octa-hedral O(6) coordination geometry is defined by two bidentate malonate ligands and two water mol-ecules, with the latter in a trans configuration. The mol-ecules are linked through O-H⋯O and N-H⋯O hydrogen-bonding inter-actions, forming a three-dimensional supra-molecular network.

  4. Diammonium diaqua­bis(malonato-κ2 O,O′)cobaltate(II) dihydrate


    The title complex, (NH4)2[Co(C3H3O4)2(H2O)2]·2H2O, features a six-coordinate Co atom located on a center of symmetry. The octahedral O6 coordination geometry is defined by two bidentate malonate ligands and two water molecules, with the latter in a trans configuration. The molecules are linked through O—H...O and N—H...O hydrogen-bonding interactions, forming a three-dimensional supramolecular network.

  5. Reference Electrodes in Metal Corrosion

    S. Szabó


    Full Text Available With especial regard to hydrogen electrode, the theoretical fundamentals of electrode potential, the most important reference electrodes and the electrode potential measurement have been discussed. In the case of the hydrogen electrode, it have been emphasised that there is no equilibrium between the hydrogen molecule (H2 and the hydrogen (H+, hydronium (H3O+ ion in the absence of a suitable catalyst. Taking into account the practical aspects as well, the theorectical basis of working of hydrogen, copper-copper sulphate, mercury-mercurous halide, silver-silver halide, metal-metal oxide, metal-metal sulphate and “Thalamid” electrodes, has been discussed.

  6. Hydronium 4-oxo-1,4-dihydropyridine-3-sulfonate dihydrate

    Zhi-Biao Zhu


    Full Text Available 2-Hydroxypyridine when treated with concentrated sulfuric acid is sulfonated at the 3-position to yield the title hydrated salt, H3O+·C5H4NO3S−·2H2O. In the crystal structure, the cations, anions and uncoordinated water molecules are linked by extensive O—H...O and N—H...O hydrogen bonds into a three-dimensional network. The crystal studied is a non-merohedral twin with a twin component of 36%.

  7. Dihydronium hexakis[bromido/chlorido(0.75/0.25]dicadmate(II–triphenylphosphine oxide (1/6

    Kong Mun Lo


    Full Text Available In the salt, (H3O2[Cd2Br4.5Cl1.5]·6C18H15OP, the hydronium cation forms short O—H...O hydrogen bonds to the O atoms of the triphenylphosphine oxide units. The centrosymmetric dinuclear anion has two halide atoms functioning in a bridging mode, which confers tetrahedral coordination to the Cd atom. The three independent halide atoms are each a mixture of bromide and chloride; the occupancies of the Br atoms are 0.6434 (11, 0.7468 (11 and 0.8598 (11.

  8. Terahertz and Infrared Laboratory Spectroscopy in Support of NASA Missions

    Yu, Shanshan


    The JPL molecular spectroscopy group supports NASA programs encompassing Astrophysics, Atmospheric Science, and Planetary Science. Ongoing activities include measurement and analysis of molecular spectra in the terahertz and infrared regions under conditions akin to the remote environments under study in NASA missions. This presentation will show the implementation of state-of-the-art spectroscopic techniques to fulfill spectroscopic demands of the Herschel Space Observatory and the Orbiting Carbon Observatory re-flight (OCO-2). A demonstrative example of the significantly improved frequency predictions for the H_3O^+ ground state high-J transitions will be given. This work was critical to Herschel's successful identification of highly excited metastable H_3O^+ Terahertz lines with J=K up to 11, one of the Herschel mission's many surprising observational results. The observation and subsequent laboratory work revealed that (1) these highly excited H_3O^+ lines had already been observed by European Southern Observatory's Atacama Pathfinder Experiment telescope a few years before but had been classified as U-lines; (2) the H_3O^+ number density was previously underestimated by an order of magnitude, due to ignorance of the population in the metastable states. A second example focuses on O_2, an important absorber from the microwave through the deep UV. This work is motivated by the challenge of developing an accurate and complete spectroscopic characterization of molecular oxygen across a wide frequency range for current and planned Earth atmospheric observations. Especially, OCO-2 utilizes the O_2 A-band for air mass calibration; extremely accurate O_2 molecular data, i.e., line positions with uncertainty on the order of MHz for the A-band around 13000 wn, are required to fulfill the demand of the proposed 0.25% precision for the carbon dioxide concentration retrievals. G. Pilbratt, J. Riedinger, T. Passvogel, G. Crone, D. Doyle, U. Gageur et al. A&A, 518, L1 (2010

  9. 4-Carbamoylpiperidinium acetate monohydrate

    Urs D. Wermuth


    Full Text Available In the structure of the title compound, C6H13N2O+·C2H3O2−·H2O, the amide H atoms of the cations form centrosymmetric cyclic hydrogen-bonding associations incorporating two water molecules [graph set R42(8], which are conjoint with cyclic water-bridged amide–amide associations [R44(12] and larger R44(20 associations involving the water molecule and the acetate anions, which bridge through the piperidinium H-bond donors, giving an overall three-dimensional framework structure.

  10. Density functional theory study of proton transfer in carbonic anhydrase

    ZHANG Lidong; XIE Daiqian


    Proton transfer in carbonic anhydrase II has been studied at the B3LYP/6-31G(D) level. The active site model consists of the zinc ion, four histidine residues, two threonine residues, and three water molecules. Our calculations showed that the proton of the zinc-bound water molecule could be transferred to the nearest water molecule and an intermediate containing H3O+ is then formed. The intermediate is only 1.3 kJ·mol-1 above the reactant complex, whereas the barrier height for the proton transfer is about 8.1 kJ·mol-1.

  11. Paniculatumoside G, a new C21 steroidal glycoside from Cynanchum paniculatum

    Hua Gao

    Full Text Available ABSTRACT A new C21 steroidal glycoside, paniculatumoside G, together with neocynapanogenin C isolated for the first time from the natural source and two known compounds were isolated and characterized from the roots and rhizomes of Cynanchum paniculatum (Bunge Kitag. ex H.Hara, Apocynaceae, a commonly used Traditional Chinese Medicine. On the basis of spectroscopic analysis, including HR-ESI-MS, 1D and 2D NMR spectral data, the structure of the new C21 steroidal glycoside was elucidated as neocynapanogenin H 3-O-β-D-oleandropyranoside.

  12. Experimental studies of the formation of cluster ions formed by corona discharge in an atmosphere containing SO2, NH3, and H2O

    Hvelplund, Preben; Pedersen, Jens Olaf Pepke; Støchkel, Kristian


    Abstract We report on studies of ion-induced nucleation in a corona discharge taking place in an atmosphere containing SO2, NH3, and H2O at standard temperature and pressure. Positive ions such as H3O+(H2O)n, NH4+(H2O)n, and H+(H2SO4)(H2O)n and negative ions such as HSO5-(H2O)n, SO4-(H2O)n, HSO4-(H...

  13. [H2N(C2H4)2NH2]4(H3O)[PMo2ⅤMo6ⅥV4ⅣO40(VⅣO)2]·H2O:A New Highly Reduced, Bicapped Pseudo—Keggin Vanadylpolymolybdophosphate

    李阳光; 王恩波; 德格吉乎; 张宏; 胡长文; 胡宁海; 贾恒庆


    A new vanadylpolymolybdophosphate,[H2N(C2H4)2NH2]4-(H3O)[PMo2ⅤMo6ⅥV4ⅣO40(VⅣO)2]·H2O,was hydrothermally synthesized and structurally characterized by elemental analyses,IR,UV-vis,XPS,ESR spectra,and single crystal X-raydiffraction analysis.The compound contains an unusual highly reduced pseudo-Keggin type polyoxoanion with nine negative charges and exhibits an interesting phosphorus-centered alter-nate layer arrangement of molybdenum and vanadium oxides.

  14. (11R-13-Dimethylammonio-11,13-dihydro-4,5-epoxycostunolide semifumarate

    Sundar Neelakantan


    Full Text Available Crystals of the title salt, C17H28NO3+·C4H3O4−, were obtained by reacting parthenolide with dimethylamine followed by conversion of the amine adduct into a water-soluble fumarate salt. Subsequent crystallization of the fumarate salt from water afforded colorless orthorhombic crystals. The amine addition is highly stereospecific yielding exclusively a single diastereomer with R-configuration at the newly formed C-11 chiral carbon. In the crystal, intermolecular O—H...O and N—H...O hydrogen bonds help to establish the packing.

  15. Hydroxonium creatininium bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6nickelate(II trihydrate

    Jafar Attar Gharamaleki


    Full Text Available The title compound, (C4H8N3O(H3O[Ni(C7H3NO42]·3H2O, exhibits isotypism with its CoII analogue. All intramolecular distances and angles are similar for the two structures. This applies also for the intermolecular forces, consisting of O—H...O and N—H...O hydrogen bonds and π–π interactions [with centroid–centroid distances of 3.428 (2 and 3.579 (2 Å], that lead to a cohesion of the structure.

  16. Poly[[aqua-μ6-benzene-1,2,3-tricarboxyl­ato-μ3-hydroxido-dizinc] hemihydrate

    Chao-Hong Ma; Qiang Liu; Xiu-Yan Wang; Xian-Wu Dong; Yu-Jie Li


    In the title compound, {[Zn2(C9H3O6)(OH)(H2O)]·0.5H2O}n, there are three independent ZnII atoms present; two are located on special positions, viz a twofold rotation axis and an inversion centre, and the third is located in a general position. The ZnII atom on the inversion centre is six-coordinated by four O atoms from four different benzene-1,2,3-tricarboxylate anions and two OH− anions. The ZnII atom located on a twofold axis is four coordinated by two O atoms from two d...

  17. Poly[tetra­aqua­(μ4-benzene-1,3,5-tri­carboxyl­ato)sodium(I)zinc(II)

    Chao-Hong Ma; Xiu-Yan Wang; Xian-Wu Dong; Yu-Jie Li


    In the title compound, [NaZn(C9H3O6)(H2O)4]n, the ZnII atom is six-coordinated by four O atoms from two different benzene-1,3,5-tricarboxylate anions and two water O atoms in a distorted tetragonal-bipyramidal geometry and the NaI atom is five-coordinated by three O atoms from three different benzene-1,3,5-tricarboxylate anions and two water O atoms in a distorted trigonal-bipyramidal geometry. The benzene-1,3,5-tricarboxylate anion bridges two ZnII atoms and two NaI atoms, resulting in the f...

  18. 4-Hydroxy-3-(1′-methyl-2-oxo-4′-phenylspiro[indoline-3,2′-pyrrolidine]-3′-ylcarbonylquinolin-2(1H-one

    K. Revathi


    Full Text Available In the title compound, C28H23N3O4, the dihedral angle between the quinoline and indole ring systems is 29.30 (5°. The pyrrolidine ring adopts a twist conformation. An intramolecular O—H...O hydrogen bond generates an S(6 ring motif. A weak intramolecular C3—H3...O3 interaction is also observed. In the crystal, molecules are linked by two sets of N—H...O hydrogen bonds, forming centrosymmetric dimers containing two R22(8 ring motifs. The dimers are linked via C—H...π interactions.

  19. The Organic Secondary Building Unit: Strong Intermolecular π Interactions Define Topology in MIT-25, a Mesoporous MOF with Proton-Replete Channels.

    Park, Sarah S; Hendon, Christopher H; Fielding, Alistair J; Walsh, Aron; O'Keeffe, Michael; Dincă, Mircea


    The structure-directing role of the inorganic secondary building unit (SBU) is key for determining the topology of metal-organic frameworks (MOFs). Here we show that organic building units relying on strong π interactions that are energetically competitive with the formation of common inorganic SBUs can also play a role in defining the topology. We demonstrate the importance of the organic SBU in the formation of Mg2H6(H3O)(TTFTB)3 (MIT-25), a mesoporous MOF with the new ssp topology. A delocalized electronic hole is critical in the stabilization of the TTF triad organic SBUs and exemplifies a design principle for future MOF synthesis.

  20. Crystal structure of 2-phenyl-ethanaminium 3-carb-oxy-prop-2-enoate.

    Sowmya, N Swarna; Sampathkrishnan, S; Akilan, R; Chakkaravarthi, G; Kumar, R Mohan


    The title mol-ecular salt, C8H12N(+)·C4H3O4 (-), crystallized with two independent cations and anions in the asymmetric unit. The ethanaminium side chains of the cations exhibit anti conformations [C-C-C-N torsion angles = 176.5 (3) and -179.4 (3)°]. In the crystal, N-H⋯O and C-H⋯O hydrogen bonds connect adjacent anions and cations, and , O-H⋯O hydrogen bonds connect adjacent anions, generating sheets parallel to (001).

  1. Crystal structure of poly[μ-acetato-bis[μ-2-oxo-2-(quinolin-8-ylethanoato]trisodium

    Rachel L. Nicholls


    Full Text Available The title compound [Na3(C11H6NO32(C2H3O2]n, crystallized through diffusion of diethyl ether into methanol as needles. There are three crystallographically independent Na+ cations present, each exhibiting a distorted octahedral coordination geometry, two through coordination by five O atoms and one N atom, and one through coordination by six O atoms. A series of intermolecular O...Na and N...Na contacts leads to the formation of chains along the a-axis direction.

  2. Kinetics and thermochemistry of polyatomic free radicals: New results and new understandings

    Gutman, David; Slagle, Irene R.


    An experimental facility for the study of the chemical kinetics of polyatomic free radicals is described which consists of a heatable tubular reactor coupled to a photoionization mass spectrometer. Its use in different kinds of chemical kinetic studies is also discussed. Examples presented include studies of the C2H3 + O2, C2H3 + HC1, CH3 + O, and CH3 + CH3 reactions. The heat of formation of C2H3 was obtained from the results of the study of the C2H3 + HC1 reaction.

  3. Drug: D02416 [KEGG MEDICUS

    Full Text Available D02416 Drug Dried aluminum hydroxide gel (JP16); Dried aluminum hydroxide gel fine ...ffecting individual organs 23 Digestive organ agents 234 Antacids 2343 Aluminum-containing agents D02416 Dried aluminum hydr...oxide gel (JP16); Dried aluminum hydroxide gel fine granules (JP16); Aluminum hydroxide, dried (USP); Aluminum hydr...granules (JP16); Aluminum hydroxide, dried (USP); Aluminum hydroxide (USP); ALterna GEL (TN); Dialume (TN) A...lH3O3 77.9898 78.0036 D02416.gif Antacid Same as: C13391 Therapeutic category: 2343 ATC code: A02AB01 map07038 Antiulcer dr

  4. Characterization of the primary hydration shell of the hydroxide ion with H2 tagging vibrational spectroscopy of the OH- ṡ (H2O)n=2,3 and OD- ṡ (D2O)n=2,3 clusters

    Gorlova, Olga; DePalma, Joseph W.; Wolke, Conrad T.; Brathwaite, Antonio; Odbadrakh, Tuguldur T.; Jordan, Kenneth D.; McCoy, Anne B.; Johnson, Mark A.


    We report the isotope-dependent vibrational predissociation spectra of the H2-tagged OH- ṡ (H2O)n=2,3 clusters, from which we determine the strongly coordination-dependent energies of the fundamentals due to the OH groups bound to the ion and the intramolecular bending modes of the water molecules. The HOH bending fundamental is completely missing in the delocalized OH- ṡ (H2O) binary complex but is recovered upon adding the second water molecule, thereby establishing that the dihydrate behaves as a hydroxide ion solvated by two essentially intact water molecules. The energies of the observed OH stretches are in good agreement with the values predicted by Takahashi and co-workers [Phys. Chem. Chem. Phys. 17, 25505 (2015); 15, 114 (2013)] with a theoretical model that treats the strong anharmonicities at play in this system with explicit coupling between the bound OH groups and the O-O stretching modes on an extended potential energy surface. We highlight a surprising similarity between the spectral signatures of OH- ṡ (H2O)3 and the excess proton analogue, H3O+ ṡ (H2O)3, both of which correspond to completed hydration shells around the proton defect. We discuss the origin of the extreme solvatochromicity displayed by both OH- and H+ in the context of the anomalously large "proton polarizabilities" of the H5O2+ and H3O2- binary complexes.

  5. Isotope effects of ground and lowest lying vibrational states of H 3 - x D x O2 - complexes

    Ansari, Narjes; Meyer, Hans-Dieter


    Isotope effects of the H 3 O2 - anion are investigated. For this, the 24 lowest excited vibrational states of the H 3 - x D x O2 - complexes, with x = 0-3, are computed using two different Hamiltonians, namely, a 7D reduced-dimensionality one with a numerical representation of the kinetic energy operator (KEO) and a 9D full-dimensionality Hamiltonian with an exact analytic KEO. The computations are carried out with the multiconfiguration time-dependent Hartree method. The obtained results show that bridge and terminal H-D exchange cause a variation in energy with or without a rearrangement of states. A clear rearrangement of fundamental modes is observed in bridge H-D exchange of the H 3 O2 - complex, where the frequency of bridge hydrogen stretching (z) is strongly lowered by substitution. The isotope effects show that rotation (ϕ), rocking (u1 + u2), wagging (u1 - u2), and O-O stretch (R) modes are sensitive to terminal H-D exchange, while the bridge-atom bending (x,y) and stretch (z) modes are sensitive to bridge H-D exchange. An influence coefficient, which measures the influence of an excitation of one mode on the various 1D reduced densities, is defined and analyzed in detail. It is shown that the D 3 O2 - complex is more strongly correlated or coupled than the other isotopologues.

  6. Direct observation of the dynamics of single metal ions at the interface with solids in aqueous solutions

    Ricci, Maria; Trewby, William; Cafolla, Clodomiro; Voïtchovsky, Kislon


    The dynamics of ions adsorbed at the surface of immersed charged solids plays a central role in countless natural and industrial processes such as crystal growth, heterogeneous catalysis, electrochemistry, or biological function. Electrokinetic measurements typically distinguish between a so-called Stern layer of ions and water molecules directly adsorbed on to the solid’s surface, and a diffuse layer of ions further away from the surface. Dynamics within the Stern layer remain poorly understood, largely owing to a lack of in-situ atomic-level insights. Here we follow the dynamics of single Rb+ and H3O+ ions at the surface of mica in water using high-resolution atomic force microscopy with 25 ms resolution. Our results suggest that single hydrated Rb+ions reside τ1 = 104 ± 5 ms at a given location, but this is dependent on the hydration state of the surface which evolves on a slower timescale of τ2 = 610 ± 30 ms depending on H3O+ adsorption. Increasing the liquid’s temperature from 5 °C to 65 °C predictably decreases the apparent glassiness of the interfacial water, but no clear effect on the ions’ dynamics was observed, indicating a diffusion-dominated process. These timescales are remarkably slow for individual monovalent ions and could have important implications for interfacial processes in electrolytes.

  7. Crystal structure of bis­(1-ethyl­pyridinium) dioxonium hexa­cyanidoferrate(II)

    Tanaka, Rikako


    The title compound, (C7H10N)2(H3O)2[Fe(CN)6] or (Etpy)2(H3O)2[Fe(CN)6] (Etpy+ is 1-ethyl­pyridinium), crystallizes in the space group Pnnm. The FeII atom of the [Fe(CN)6]4− anion lies on a site with site symmetry ..2/m, and has an octa­hedral coordination sphere defined by six cyanido ligands. Both the Etpy+ and the oxonium cations are located on a mirror plane. In the crystal, electron-donor anions of [Fe(CN)6]4− and electron-acceptor cations of Etpy+ are each stacked parallel to the b axis, resulting in a columnar structure with segregated moieties. The crystal packing is stabilized by a three-dimensional O—H⋯N hydrogen-bonding network between the oxonium ions and the cyanide ligands of [Fe(CN)6]4−. PMID:28217346

  8. Covalently-bonded grafting of [Ln3(Benzimidazole)4]-arrayed (Ln = Tb, Nd, Yb or Er) complex monomers into PNBE (poly(norbornene)) with highly luminous color-purity green-light or efficient NIR luminescence

    Liu, Lin; Fu, Guorui; Feng, Heini; Guan, Jiaqing; Li, Fengping; Lü, Xingqiang; Wong, Wai-Kwok; Jones, Richard A.


    Within series of Ln3-grafted polymers Poly({[Ln3(L)4(NO3)6]·(NO3)·(H3O)2}-co-NBE) (Ln = La, 1; Ln = Eu, 2; Ln = Tb, 3; Ln = Nd, 4; Ln = Yb, 5; Ln = Er, 6 or Ln = Gd, 7) obtained from ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with each of allyl-functionalized complex monomers {[Ln3(L)4(NO3)6]·(NO3)·(H3O)2} (HL = 4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol), PNBE-assisted effective energy transfer renders Poly(3-co-NBE) Tb3+-centered highly luminous color-purity green-light with an attractive quantum yield of 87% and efficient near-infrared (NIR) luminescence (ΦNdL = 0.61%; ΦYbL = 1.47% and ΦErL = 0.03%) for Nd3+-, Yb3+- or Er3+-grafted polymers.

  9. Photochemistry of HI on argon and water nanoparticles: hydronium radical generation in HI·(H2O)n.

    Poterya, Viktoriya; Fedor, Juraj; Pysanenko, Andriy; Tkáč, Ondřej; Lengyel, Jozef; Ončák, Milan; Slavíček, Petr; Fárník, Michal


    Photochemistry of HI molecules on large Ar(n) and (H(2)O)(n), n ∼ 100-500, clusters was investigated after excitation with 243 nm and 193 nm laser radiation. The measured H-fragment kinetic energy distributions pointed to a completely different photodissociation mechanism of HI on water than on argon clusters. Distinct features corresponding to the fragment caging (slow fragments) and direct exit (fast fragments) were observed in the spectra from HI photodissociation on Ar(n) clusters. On the other hand, the fast fragments were entirely missing in the spectrum from HI·(H(2)O)(n) and the slow-fragment part of the spectrum had a different shape from HI·Ar(n). The HI·(H(2)O)(n) spectrum was interpreted in terms of the acidic dissociation of HI on (H(2)O)(n) in the ground state, and hydronium radical H(3)O formation following the UV excitation of the ionically dissociated species into states of a charge-transfer-to-solvent character. The H(3)O generation was proved by experiments with deuterated species DI and D(2)O. The experiment was complemented by ab initio calculations of structures and absorption spectra for small HI·(H(2)O)(n) clusters, n = 0-5, supporting the proposed model.

  10. Highly photoconducting O2-doped CdS films deposited by spray pyrolysis

    Richards, D.; El-Korashy, A. M.; Stirn, R. J.; Karulkar, P. C.


    CdS films have been prepared by spraying in air solutions of thiourea with either cadmium chloride or cadmium acetate with varying mole ratio and substrate temperature, and subsequently heat treating in oxygen. Substrates included both bare glass or sapphire and transparent conducting oxide-coated sapphire for electrical measurements lateral and transverse to the CdS plane, respectively. Dark resistances of over 10 to the 14th ohms and light-to-dark conductivities of up to 10 to the 7th were obtained using uncoated substrates. The use of Cd(C2H3O2)2 in place of CdCl2 greatly increased the speed of response although with some sacrifice in photoconductivity. Deposition of CdS on ITO-coated surfaces led to greatly reduced dark resistances for the case of CdCl2, but not Cd(C2H3O2)2, presumably due to HCl reaction with the ITO coating in the course of spraying with the former. Ion microprobe analysis detected indium within the CdS films exhibiting low dark resistance. Measurements of the dark and light conductivities at temperatures down to 77 K are given as are the response times for unetched and HCl-etched surfaces.

  11. A corona discharge atmospheric pressure chemical ionization source with selective NO(+) formation and its application for monoaromatic VOC detection.

    Sabo, Martin; Matejčík, Štefan


    We have developed a new type of corona discharge (CD) for atmospheric pressure chemical ionization (APCI) for application in ion mobility spectrometry (IMS) as well as in mass spectrometry (MS). While the other CD-APCI sources are able to generate H3O(+)·(H2O)n as the major reactant ions in N2 or in zero air, the present CD-APCI source has the ability to generate up to 84% NO(+)·(H2O)n reactant ions in zero air. The change of the working gas from zero air to N2 allows us to change the major reactant ions from NO(+)·(H2O)n to H3O(+)·(H2O)n. In this paper we present the description of the new CD-APCI and discuss the processes associated with the NO(+) formation. The selective formation of NO(+)·(H2O)n reactant ions offers chemical ionization based on these ions which can be of great advantage for some classes of chemicals. We demonstrate here a significant increase in the sensitivity of the IMS-MS instrument for monoaromatic volatile organic compound (VOC) detection upon NO(+)·(H2O)n chemical ionization.

  12. Corona discharge ion mobility spectrometry with orthogonal acceleration time of flight mass spectrometry for monitoring of volatile organic compounds.

    Sabo, Martin; Matejčík, Štefan


    We demonstrate the application of corona discharge ion mobility spectrometry with orthogonal acceleration time of flight mass spectrometry (CD IMS-oaTOF) for volatile organic compounds (VOCs) monitoring. Two-dimensional (2D) IMS-oaTOF spectra of VOCs were recorded in nearly real time. The corona discharge atmospheric pressure chemical ionization (APCI) source was operated in positive mode in nitrogen and air. The CD ion source generates in air H(3)O(+)(H(2)O)(n) and NO(+). The NO(+) offers additional possibility for selective ionization and for an increase of the sensitivity of monoaromatic compounds. In addition to H(3)O(+)(H(2)O)(n) and NO(+), we have carried out ionization of VOCs using acetone as dopant gas ((CH(3))(2)COH(+)). Sixteen model VOCs (tetrahydrofuran, butanol, n-propanol, iso-propano, acetone, methanol, ethanol, toluene, benzene, amomnia, dioxan, triethylamine, acetonitrile, formaldehyde, m-xylene, 2,2,2-trifluoroethylamine) were tested using these ionization techniques.

  13. Self-assembled silver polyhedra with embedded acetylide dianion stabilized by perfluorocarboxylate and 4-hydroxyquinoline ligands.

    Zhao, Xiao-Li; Wang, Quan-Ming; Mak, Thomas C W


    Four new silver(I) double salts (L(2)H)(4)[Ag(10)(C(2))(CF(3)CO(2))(12)(L)(2)].5H(2)O (1), [Ag(8)(C(2))(CF(3)CO(2))(6)(L)(6)] (2), [(Ag(2)C(2))(AgC(2)F(5)CO(2))(6)(L)(3)(H(2)O)].H(2)O (3), and (L.H(3)O)(2)[Ag(11)(C(2))(2)(C(2)F(5)CO(2))(9)(H(2)O)(2)].H(2)O (4) incorporating the hitherto unexplored ligand 4-hydroxyquinoline (L) have been synthesized by the hydrothermal method. Compound 1 features an unprecedented bicapped square-antiprismatic Ag(10) silver cage with an embedded C(2)(2-) moiety, whereas the discrete supermolecule 2 bears a rhombohedral Ag(8) core similar to that previously found in Ag(2)C(2).6AgNO(3). Compound 3 contains a discrete supramolecular complex whose core is a (C(2))(2)@Ag(16) double cage constructed from the edge-sharing of two monocapped square antiprisms, which is completely surrounded by 12 pentafluoropropionate, 6 4-hydroxyquinoline, and 2 aqua ligands. The layer structure in 4 is constructed from a sinuous anionic silver column composed of fused irregular monocapped trigonal antiprisms each encapsulating a C(2)(2-) dianion, with L.H(3)O(+) species serving as hydrogen-bond connectors to adjacent columns.

  14. Stereoretentive formylation of (S)-proline

    Temizsoy, Mehmet; Sethi, Waqas; Reinholdt, Anders


    In a Vilsmeier-Haack-type formylation reaction the α-(dihydroxymethyl)-(S)-prolinato complex (+)578-p-[Co(tren){(RC,SN)-Pro[CH(OH)2]O}]Cl2·2H2O (22) was produced stereoselectively (85% ee) from the (S)-prolinato complex, (+)578-p-[Co(tren){(SC,SN)-ProO}]2(H3O)2(HOEt2)(O3SCF3)7 (18). Similar...... reaction of the (S)-alaninato complex, (-)578-p-[Co(tren)(S-AlaO)](H3O)(O3SCF3)3 (13), produced the racemate, rac-p-[Co(tren)(Ala{CH(OH)2}O)]SO4·2H2O (17). The contrasting stereochemical outcomes of the formylation reaction with 18versus13 were ascribed to the stereogenic character of the coordinated sec....... amine of the (S)-prolinate chelate in 18, which serves to uphold a chiral environment during reaction, whereas reaction intermediates derived from 13 lack this stereochemical feature. The stereoselective formylation of (S)-proline, relying on coordination to an inert metal centre, as conducted here...

  15. Acid-Catalyzed Hydration of anti-Sesquinorbornene.

    Slebocka-Tilk, H.; Brown, R. S.


    The acid-catalyzed hydration of anti-sesquinorbornene (1) has been studied at 25 degrees C in 20% DME/H(2)O from 0.001 M kinetic isotope effect for hydration of 1 is 2.7, and a plot of the observed second-order rate constant for the hydration in a mixed solvent system of H(2)O/D(2)O against the atom fraction of deuterium (n) is bowed upward. The reaction also shows marked buffer catalysis by formic, chloroacetic, and dichloroacetic acids, the Brønsted alpha being 1 for these three carboxylic acids: H(3)O(+) does not fit on this Brønsted line. A mechanism for the reaction is presented which is consistent with the generally accepted one for acid-catalyzed hydration of an alkene in which the rate-limiting step involves proton transfer from H(3)O(+) to the double bond. Whether attack of a second water on the developing carbocation occurs simultaneously with protonation cannot be ascertained from the data for 1, but if so, the extent of its C-OH(2) bond formation must be small enough that there is little change in the bonding of these O-H bonds.

  16. Tracing the Physical Conditions in Active Galactic Nuclei with Time-Dependent Chemistry

    Meijerink, Rowin; Kamp, Inga; Aresu, Giambattista; Thi, Wing-Fai; Woitke, Peter


    We present an extension of the code ProDiMo that allows for a modeling of processes pertinent to active galactic nuclei and to an ambient chemistry that is time dependent. We present a proof-of-concept and focus on a few astrophysically relevant species, e.g., H+, H2+ and H3+; C+ and N+; C and O; CO and H2O; OH+, H2O+ and H3O+; HCN and HCO+. We find that the freeze-out of water is strongly suppressed and that this affects the bulk of the oxygen and carbon chemistry occurring in AGN. The commonly used AGN tracer HCN/HCO+ is strongly time-dependent, with ratios that vary over orders of magnitude for times longer than 10^4 years. Through ALMA observations this ratio can be used to probe how the narrow-line region evolves under large fluctuations in the SMBH accretion rate. Strong evolutionary trends, on time scales of 10^4-10^8 years, are also found in species such as H3O+, CO, and H2O. These reflect, respectively, time dependent effects in the ionization balance, the transient nature of the production of molecu...

  17. Quantification of trace levels of the potential cancer biomarkers formaldehyde, acetaldehyde and propanol in breath by SIFT-MS.

    Spaněl, Patrik; Smith, David


    The sensitivity of selected ion flow tube mass spectrometry, SIFT-MS, has been increased such that it is now possible to detect metabolites present at a part-per-billion, ppb, level in single breath exhalations. However, to utilize this improved sensitivity, the overlaps (coincidences) of those ions resulting from interfering reactions of impurity precursor ions with some breath metabolites present at higher concentrations with the analytical product ions characteristic of particular metabolites must be accounted for. In this paper, the full reaction schemes are presented for SIFT-MS analyses of three volatile potential cancer biomarkers in exhaled breath, namely formaldehyde, HCHO, acetaldehyde, CH(3)CHO and 2-propanol, CH(3)CH(OH)CH(3), which identify both the characteristic SIFT-MS product ions for these compounds and the interfering ions at the same mass-to-charge, m/z, values. An absolute quantification equation accounting for these interferences is formulated and appropriate entries into the SIFT-MS kinetics library are indicated. It is shown that when using H(3)O(+) to quantify formaldehyde and acetaldehyde the reactions of impurity O(2)(+) ions with methanol and ethanol (always present in breath) must be accounted for and that the quantification of acetaldehyde must avoid the interference of the CO(2) present in exhaled breath. Finally, it is indicated that the analysis of 2-propanol can be achieved using both H(3)O(+) and NO(+) precursor ions.

  18. Precipitation of barium flouride microcrystals from electrolytic solutions: The influence of the composition of the precipitating solutions

    Kolar, Z.; Binsma, J. J. M.; Subotić, B.


    The composition, shape and size of the particles obtained by precipitation in aqueous solutions of various barium salts (chloride, nitrate and acetate) with various fluorides (ammonium, sodium and hydrogen) have been studied by X-ray powder diffraction analysis and scanning electron microscopy. From Ba(NO 3) 2 in combination with NH 4F or NaF and from Ba(C 2H 3O 2) 2 in combination with NH 4F, NaF or HF, precipitates of pure cubic-BaF 2 (β-BaF 2) are obtained. The shape and size of β-BaF 2 particles depend on the combination of the compounds used for the precipitation and their concentrations. It appears that only when (equal volumes of) solutions of Ba(NO 3) 2 (0.125 mol dm -3) or Ba(C 2H 3O 2) 2 (0.125 and 0.150 mol dm -3) and NH 4F (0.250 or 0.300 mol dm -3) are mixed particles are formed as more or less regular cubes with smooth faces. These crystals are suitable to be used in studies of the transport of ions from crystals to the solution and vice versa with the aid of radioactive tracers ("heterogeneous isotopic exchange" studies).

  19. Proton conduction and long-range ferrimagnetic ordering in two isostructural Copper(II) mesoxalate metal-organic frameworks.

    Gil-Hernández, Beatriz; Savvin, Stanislav; Makhloufi, Gamall; Núñez, Pedro; Janiak, Christoph; Sanchiz, Joaquín


    Two compounds of formula {(H3O)[Cu7(Hmesox)5(H2O)7]·9H2O}n (1a) and {(NH4)0.6(H3O)0.4[Cu7(Hmesox)5(H2O)7]·11H2O}n (1b) were prepared and structurally characterized by single-crystal X-ray diffraction (H4mesox = mesoxalic acid, 2-dihydroxymalonic acid). The compounds are crystalline functional metal-organic frameworks exhibiting proton conduction and magnetic ordering. Variable-temperature magnetic susceptibility measurements reveal that the copper(II) ions are strongly ferro- and antiferromagnetically coupled by the alkoxide and carboxylate bridges of the mesoxalate linker to yield long-range magnetic ordering with a Tc of 17.6 K, which is reached by a rare mechanism known as topologic ferrimagnetism. Electric conductivity, measured by impedance methods, shows values as high as 6.5 × 10(-5) S cm(-1) and occurs by proton exchange among the hydronium/ammonium and water molecules of crystallization, which fill the voids left by the three-dimensional copper(II) mesoxalate anionic network.

  20. Inter-action between maleic acid and N-R-furfuryl-amines: crystal structure of 2-methyl-N-[(5-phenyl-furan-2-yl)meth-yl]propan-2-aminium (2Z)-3-carb-oxy-acrylate and N-[(5-iodo-furan-2-yl)meth-yl]-2-methyl-propan-2-aminium (2Z)-3-carb-oxy-prop-2-enoate.

    Kvyatkovskaya, Elisaveta A; Zaytsev, Vladimir P; Zubkov, Fedor I; Dorovatovskii, Pavel V; Zubavichus, Yan V; Khrustalev, Victor N


    The title mol-ecular salts, C15H20NO(+)·C4H3O4(-), (I), and C9H15INO(+)·C4H3O4(-), (II), have very similar mol-ecular geometries for both cation and anion. The anions of both (I) and (II) are practically planar (r.m.s. deviations = 0.062 and 0.072 Å, respectively) and adopt a rare symmetrical geometry with the hy-droxy H atom approximately equidistant from the two O atoms. In their crystals, the cations and anions in both (I) and (II) form tight ionic pairs via strong N-H⋯O hydrogen bonds, with a roughly perpendicular disposition of the anion to the furan ring of the cation. This ion-pair conformation appears to correlate with the lack of reactivity of these salts in [4 + 2] cyclo-addition reactions. In the extended structures of (I) and (II), the ion pairs form hydrogen-bonded chains propagating along [010] and [001], respectively, via N-H⋯O hydrogen bonds.

  1. Two novel Co(II complexes with two different Schiff bases: inhibiting growth of human skin cancer cells

    Y.-J. Xiao

    Full Text Available Using two flexible Schiff bases, H2L1 and H2L2, two new cobalt II (Co(II-coordination compounds, namely, Py3CoL1 (1 and Py3CoL2 (2 (Py=pyridine, L1=3,5-ClC6H2(OC=NC6H3(O-4-NO2, L2=3,5-BrC6H2(OC=NC6H3(O-4-NO2 have been synthesized under solvothermal conditions. Single crystal X-ray structural analysis revealed that compounds 1 and 2 are both six-coordinate in a distorted octahedral geometry, and the 1D chain structure was formed by the π…π and C-H…O interactions or C-H…Cl interaction. The in vitro antitumor activities of 1, 2 and their corresponding organic ligands Py, L1, and L2 were studied and evaluated, in which three human skin cancer cell lines (A-431, HT-144 and SK-MEL-30 were used in the screening tests.

  2. New 1:1 and 2:1 salts in the `DL-norvaline-maleic acid' system as an example of assembling various crystal structures from similar supramolecular building blocks.

    Arkhipov, Sergey G; Losev, Evgeniy A; Boldyreva, Elena V


    Molecular salts and cocrystals of amino acids have potential applications as molecular materials with nonlinear optical, ferroelectric, piezoelectric, and other various target physical properties. The wide choice of amino acids and coformers makes it possible to design various crystal structures. The amino acid-maleic acid system provides a perfect example of a rich variety of crystal structures with different stoichiometries, symmetries and packing motifs built from the molecular building blocks, which are either exactly the same, or differ merely by protonation or as optical isomers. The present paper reports the crystal structures of two new salts of the DL-norvaline-maleic acid system with 1:1 and 2:1 stoichiometries, namely DL-norvalinium hydrogen maleate, C5H12NO2(+)·C4H3O4(-), (I), and DL-norvalinium hydrogen maleate-DL-norvaline, C5H12NO2(+)·C4H3O4(-)·C5H11NO2, (II). These are the first examples of molecular salts of DL-norvaline with an organic anion. The crystal structure of (I) has the same C2(2)(12) structure-forming motif which is common for hydrogen maleates of amino acids. The structure of (II) has dimeric cations. Of special interest is that the single crystals of (I) which are originally formed on crystallization from aqueous solution transform into single crystals of (II) if stored in the mother liquor for several hours.

  3. Detection of OH$^+$ and H$_2$O$^+$ towards Orion~KL

    Gupta, H; Pearson, J C; Yu, S; Herbst, E; Harada, N; Bergin, E A; Neufeld, D A; Melnick, G J; Bachiller, R; Baechtold, W; Bell, T A; Blake, G A; Caux, E; Ceccarelli, C; Cernicharo, J; Chattopadhyay, G; Comito, C; Cabrit, S; Crockett, N R; Daniel, F; Falgarone, E; Diez-Gonzalez, M C; Dubernet, M -L; Erickson, N; Emprechtinger, M; Encrenaz, P; Gerin, M; Gill, J J; Giesen, T F; Goicoechea, J R; Goldsmith, P F; Joblin, C; Johnstone, D; Langer, W D; Larsson, B; Latter, W B; Lin, R H; Lis, D C; Liseau, R; Lord, S D; Maiwald, F W; Maret, S; Martin, P G; Martin-Pintado, J; Menten, K M; Morris, P; Müller, H S P; Murphy, J A; Nordh, L H; Olberg, M; Ossenkopf, V; Pagani, L; Pérault, M; Phillips, T G; Plume, R; Qin, S -L; Salez, M; Samoska, L A; Schilke, P; Schlecht, E; Schlemmer, S; Szczerba, R; Stutzki, J; Trappe, N; van der Tak, F F S; Vastel, C; Wang, S; Yorke, H W; Zmuidzinas, J; Boogert, A; Güsten, R; Hartogh, P; Honingh, N; Karpov, A; Kooi, J; Krieg, J -M; Schieder, R; Zaal, P


    We report observations of the reactive molecular ions OH$^+$, H$_2$O$^+$, and H$_3$O$^+$ towards Orion KL with Herschel/HIFI. All three $N=1-0$ fine-structure transitions of OH$^+$ at 909, 971, and 1033GHz and both fine-structure components of the doublet {\\it ortho}-H$_2$O$^+$ $1_{11}-0_{00}$ transition at 1115 and 1139GHz were detected; an upper limit was obtained for H$_3$O$^+$. OH$^+$ and H$_2$O$^+$ are observed purely in absorption, showing a narrow component at the source velocity of 9 kms$^{-1}$, and a broad blueshifted absorption similar to that reported recently for HF and {\\it para}-H$_{2}^{18}$O, and attributed to the low velocity outflow of Orion KL. We estimate column densities of OH$^+$ and H$_2$O$^+$ for the 9 km s$^{-1}$ component of $9 \\pm 3 \\times 10^{12}$cm$^{-2}$ and $7 \\pm 2 \\times 10^{12}$cm$^{-2}$, and those in the outflow of $1.9 \\pm 0.7 \\times 10^{13}$cm$^{-2}$ and $1.0 \\pm 0.3 \\times 10^{13}$cm$^{-2}$. Upper limits of $2.4\\times 10^{12}$cm$^{-2}$ and $8.7\\times 10^{12}$cm$^{-2}$ were...

  4. Single crystal X-ray structure of the artists' pigment zinc yellow

    Simonsen, Kim Pilkjær; Christiansen, Marie Bitsch; Vinum, Morten Gotthold; Sanyova, Jana; Bendix, Jesper


    The artists' pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hitherto been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2- moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type.

  5. Using the pseudophase kinetic model to interpret chemical reactivity in ionic emulsions: determining antioxidant partition constants and interfacial rate constants.

    Gu, Qing; Bravo-Díaz, Carlos; Romsted, Laurence S


    Kinetic results obtained in cationic and anionic emulsions show for the first time that pseudophase kinetic models give reasonable estimates of the partition constants of reactants, here t-butylhydroquinone (TBHQ) between the oil and interfacial region, P(O)(I), and the water and interfacial region, P(W)(I), and of the interfacial rate constant, k(I), for the reaction with an arenediazonium ion in emulsions containing a 1:1 volume ratio of a medium chain length triglyceride, MCT, and aqueous acid or buffer. The results provide: (a) an explanation for the large difference in pH, >4 pH units, required to run the reaction in CTAB (pH 1.54, added HBr) and SDS (pH 5.71, acetate buffer) emulsions; (b) reasonable estimates of PO(I) and k(I) in the CTAB emulsions; (c) a sensible interpretation of added counterion effects based on ion exchange in SDS emulsions (Na(+)/H3O(+) ion exchange in the interfacial region) and Donnan equilibrium in CTAB emulsions (Br(-) increasing the interfacial H3O(+)); and (d) the significance of the effect of the much greater solubility of TBHQ in MCT versus octane, 1000/1, as the oil. These results should aid in interpreting the effects of ionic surfactants on chemical reactivity in emulsions in general and in selecting the most efficient antioxidant for particular food applications.

  6. Why does hydronium diffuse faster than hydroxide in liquid water?

    Zheng, Lixin; Santra, Biswajit; Distasio, Robert; Klein, Michael; Car, Roberto; Wu, Xifan

    Experiments show that the hydronium ion (H3O+) diffuses much faster than the hydroxide ion (OH-) in liquid water. ab initio molecular dynamics (AIMD) simulations correctly associated the diffusion mechanism to proton transfer (PT) but have been unable so far to clearly identify the reason for the faster diffusion of hydronium compared to hydroxide, as the diffusion rate was found to depend sensitively on the adopted functional approximation. We carried out AIMD simulations of the solvated water ions using a van der Waals (vdW) inclusive PBE0 hybrid density functional. It is found that not only hydronium diffuses faster than hydroxide but also the absolute rates agree with experiment. The fast diffusion of H3O+ occurs via concerted PT that enables the ion to jump across several H-bonded molecules in successful transfer events; in contrast, such concerted motion is significantly hindered in OH- where the ion is easily trapped in a hyper-coordination configuration (a local solvation structure that forbids PT). As a result multiple PT events are rare and the diffusion of OH- is significantly slowed down. Such a clear difference between the two ions results from the combined effect of vdW interactions and self-interaction correction. Doe SciDac: DE-SC0008626 and DE-SC0008726.

  7. RRKM and master equation kinetic analysis of parallel addition reactions of isomeric radical intermediates in hydrocarbon flames

    Winter, Pierre M.; Rheaume, Michael; Cooksy, Andrew L.


    We have calculated the temperature-dependent rate coefficients of the addition reactions of butadien-2-yl (C4H5) and acroylyl (C3H3O) radicals with ethene (C2H4), carbon monoxide (CO), formaldehyde (H2CO), hydrogen cyanide (HCN), and ketene (H2CCO), in order to explore the balance between kinetic and thermodynamic control in these combustion-related reactions. For the C4H5 radical, the 1,3-diene form of the addition products is more stable than the 1,2-diene, but the 1,2-diene form of the radical intermediate is stabilized by an allylic delocalization, which may influence the relative activation energies. For the reactions combining C3H3O with C2H4, CO, and HCN, the opposite is true: the 1,2-enone form of the addition products is more stable than the 1,3-enone, whereas the 1,3-enone is the slightly more stable radical species. Optimized geometries and vibrational modes were computed with the QCISD/aug-cc-pVDZ level and basis, followed by single-point CCSD(T)-F12a/cc-pVDZ-F12 energy calculations. Our findings indicate that the kinetics in all cases favor reaction along the 1,3 pathway for both the C4H5 and C3H3O systems. The Rice-Ramsperger-Kassel-Marcus (RRKM) microcanonical rate coefficients and subsequent solution of the chemical master equation were used to predict the time-evolution of our system under conditions from 500 K to 2000 K and from 10-5 bar to 10 bars. Despite the 1,3 reaction pathway being more favorable for the C4H5 system, our results predict branching ratios of the 1,2 to 1,3 product as high as 0.48 at 1 bar. Similar results hold for the acroylyl system under these combustion conditions, suggesting that under kinetic control the branching of these reactions may be much more significant than the thermodynamics would suggest. This effect may be partly attributed to the low energy difference between 1,2 and 1,3 forms of the radical intermediate. No substantial pressure-dependence is found for the overall forward reaction rates until pressures

  8. Synthesis, characterization and single crystal x-ray analysis of a complex of iron(II) bis(2,4-dimethylphenyl)dithiophosphate with 4-ethylpyridine

    Kumar, Sandeep; Andotra, Savit; Kaur, Mandeep; Gupta, Vivek K.; Kant, Rajni; Pandey, Sushil K.


    Complex of iron(II) bis(2,4-dimethylphenyl)dithiophosphate with 4-ethylpyridine [{(2,4- (CH3)2C6H3O)2PS2}2Fe{NC5H4(C2H5)-4}2] is synthesized and characterized by elemental analysis, magnetic moment, IR spectroscopy and single crystal X-ray analysis. Complex crystallizes in the monoclinic sp. gr. P21/ n, Z = 2. Crystal structure consists of mononuclear units with Fe(II) ion chelated by four S atoms of the two diphenyldithiophosphate ligands in bidentate manner. N atoms from two 4-ethylpyridine ligands are axially coordinated to the Fe(II) atom leading to an octahedral geometry.

  9. Heavy main-group iodometallates hybridized by alkali metal via 1,10-Phenanthroline-5,6-dione

    Mengfan Yin; Gengxing Cai; Peng Wang; Xihui Chao; Jibo Liu; Haohong Li; Zhirong Chen


    Alkali metals were introduced into heavy main-group iodometallates to get two new IA/IVAheterometallic frameworks [PbI3K(pdon)(H2O)2] (1) and {[Pb3I9K2(pdon)2(H3O)]·H2O} (2) (pdon=1,10-phenanthroline-5,6-dione), which were obtained as single phases by hydrothermal method at different pH values. Compounds 1 and 2 are three-dimensional heterometallic frameworks constructed from the linkage of pdon ligand between iodometallate chains and potassium oxides/iodide clusters. Specially, these two heterometallic frameworks exhibit broadened absorption bands at 700 and 750 nm compared with those of bulk PbI2 and pdon ligand. The band gap of 2 is wider than that of 1, which is due to the absence of · · · interaction in 2. Their thermal stabilities are also discussed.

  10. Comparison of CBS-QB3, CBS-APNO, G2, and G3 thermochemical predictions with experiment for formation of ionic clusters of hydronium and hydroxide ions complexed with water.

    Pickard, Frank C; Pokon, Emma K; Liptak, Matthew D; Shields, George C


    The GAUSSIAN 2, GAUSSIAN 3, complete basis set-QB3, and complete basis set-APNO methods have been used to calculate DeltaH( composite function) and DeltaG( composite function) values for ionic clusters of hydronium and hydroxide ions complexed with water. Results for the clusters H3O+(H2O)n and OH-(H2O)n, where n=1-4 are reported in this paper, and compared against experimental values contained in the National Institutes of Standards and Technology (NIST) database. Agreement with experiment is excellent for the three ab initio methods for formation of these clusters. The high accuracy of these methods makes them reliable for calculating energetics for the formation of ionic clusters containing water. In addition this allows them to serve as a valuable check on the accuracy of experimental data reported in the NIST database, and makes them useful tools for addressing unresolved issues in atmospheric chemistry.

  11. Ion transport in some solid state proton conducting composites studied from volta cell e.m.f. and complex impedance spectroscopy

    N Lakshmi; S Chandra


    Proton conducting composites of heteropolyacid hydrates (phosphomolybdic acid H3PMo12O40.H2O,PMA; phosphotungstic acid H3PW12O40.H2O, PTA) and salt hydrate like NiCl2.6H2O were prepared with insulating Al2O3 as dispersoid. The ionic conductivity peaks at two concentrations of Al2O3 indicating two percolation thresholds for proton conduction. Two separate experiments were carried out to check the existence of such percolation thresholds viz. the volta battery experiment involving the measurement of e.m.f. of an electrochemical cell with composites of different compositions used as electrolyte and the composition vs conductivity measured by the complex impedance spectroscopy. The presence of two maxima has been attributed to two different percolation thresholds for the two possible mobile protonic species + (H3O+) and OH– arising from the hydrates.

  12. Poly[octa-μ-aqua-tetraaquabis(μ-5-sulfonatobenzene-1,3-dicarboxylatocobalt(IItetrasodium

    Bing-Yu Zhang


    Full Text Available The title compound, [CoNa4(C8H3O7S2(H2O12]n, is a three-dimensional coordination polymer bridged by sulfoisophthalate trianions and water molecules. The CoII atom, located on an inversion centre, is coordinated by two carboxylate groups of the sulfoisophthalate trianions and by four water molecules in a distorted CoO6 octahedral geometry. Two independent NaI atoms also have a distorted octahedral coordination geometry formed by water, carboxylate O and sulfonate O atoms. An extensive O—H...O and C—H...O hydrogen-bonding network is present in the crystal structure, as well as weak π-π stacking [centroid–centroid distance = 3.9553 (11 Å].

  13. Poly(2-FurylMethylenesulfide as a Resin to Uptake of Metal Ions from Aqueous Solutions

    Damasceno J.


    Full Text Available The polymerization of poly (2- furyl methylenesulfide -- POLYTHIOFURFURAL -- was performed in an 0.36 mol/L aqueous solution of furfuraldehyde, saturated by bubbling hydrogen sulfide for 2 h at different temperatures. The reaction product was thoroughly washed and dried at 40 °C under vacuum. Poly (2-furyl methylenesulfyde is a yellow powder with a rather unpleasant odor. The polythiofurfural obtained [ -CH(C4H3O-S-] is a furan with thiols end groups. These are active adsorption centers for metal ions. The polythiofurfural was soluble in acetone and chloroform and its yields attained 80%. Morphological analysis by Scanning Eletronic Microscopy indicates a regular and dense surface in an interesting spacial arrangement. Preliminary isotherms adsorption studies indicate specific affinity forNi (II and Co (II and different capacity adsorption, 0.022 and 0.045 mmol per gram, respectively.

  14. Hydronium (3-oxo-1-phosphono-1,3-dihydroisobenzofuran-1-ylphosphonate

    Nathalie Dupont


    Full Text Available In the title compound, H3O+·C8H7O8P2−, the anions form inversion dimmers by way of pairs of O—H...O hydrogen bonds involving the phosphonic functions and via the hydronium cation. Further O—H...O links involving the hydronium cation play a prominant part in the cohesion of the crystal structure by building bridges between bisphosphonate pairs, forming infinite ribbons along the b-axis direction and by cross-linking these ribbons perpendicularly along the a-axis direction, forming an infinite three-dimensional hydrogen-bond network. The benzene ring and the C=O atoms of the furan ring are disordered over two sets of positions of equal occupancy.

  15. Kinetics of proton transport in water

    Kornyshev, A.A.; Kuznetsov, A.M.; Spohr, E.


    for rationalizing the excess proton mobility, based on computer simulations, theory of proton transfer (PT) in condensed media, and analysis of classical proton conductivity experiments over broad temperature ranges. The mechanistic options involved are (i) classical hydrodynamic motion of the hydronium ion (H3O......+), (ii) proton transfer from hydronium to a neighboring water molecule, and (iii) structural diffusion of the Zundel complex (H5O2+), the processes all controlled by orientational fluctuations or hydrogen bond breaking in neighboring hydration shells. Spontaneous conversion of excess proton states...... between Zundel and hydrated hydronium states and between hydrated and bare hydronium states are the crucial parts of the scheme. A comparison between experimental data and molecular dynamics (MD) simulations shows that prototropic structural diffusion is determined by comparable contributions...

  16. Hydronium perchlorate–dibenzo-18-crown-6 (1/1: monoclinic polymorph

    Michaela Pojarová


    Full Text Available The asymmetric unit of the title compound, H3O+·ClO4−·C20H24O6, contains two molecules/ions of each species. Both dibenzo-18-crown-6 molecules have a complexed hydronium ion inside their cavity with O—H...O and O—H...(O,O links between the two species. The associated perchlorate anions also accept O—H...O hydrogen bonds from the hydronium ion. Both crown ether molecules are present in a butterfly conformation with approximate C2v symmetry and their cavities are closed by the benzene ring of a neighbouring molecule. The packing is consolidated by C—H...O and C—H...π interactions.

  17. Hexa-μ2-acetato-1:2κ4O:O′;1:2κ2O:O;2:3κ4O:O′;2:3κ2O:O-bis(2-amino-7-chloro-5-methyl-1,8-naphthyridine-1κN1,3κN1-trizinc(II

    Su-Mei Zhang


    Full Text Available The title complex, [Zn3(C2H3O26(C9H8ClN32], contains three ZnII atoms bridged by six acetate ligands. The central ZnII ion, located on an inversion centre, is surrounded by six O atoms from acetate ligands in a distorted octahedral geometry [Zn—O = 1.9588 (12–2.1237 (12 Å]. The terminal ZnII ions are coordinated by one N atom of 2-amino-7-chloro-5-methyl-1,8-naphthyridine and three O atoms of three acetate ligands in a distorted tetrahedral geometry. The separation between the central and terminal ZnII ions is 3.245 (3 Å.

  18. Cooperativity in Surface Bonding and Hydrogen Bonding of Water and Hydroxyl at Metal Surfaces

    Schiros, T.; Ogasawara, H.; Naslund, L. A.;


    of the mixed phase at metal surfaces. The surface bonding can be considered to be similar to accepting a hydrogen bond, and we can thereby apply general cooperativity rules developed for hydrogen-bonded systems. This provides a simple understanding of why water molecules become more strongly bonded...... to the surface upon hydrogen bonding to OH and why the OH surface bonding is instead weakened through hydrogen bonding to water. We extend the application of this simple model to other observed cooperativity effects for pure water adsorption systems and H3O+ on metal surfaces.......We examine the balance of surface bonding and hydrogen bonding in the mixed OH + H2O overlayer on Pt(111), Cu(111), and Cu(110) via density functional theory calculations. We find that there is a cooperativity effect between surface bonding and hydrogen bonding that underlies the stability...

  19. Kinetics of proton transport in water

    Kornyshev, A.A.; Kuznetsov, A.M.; Spohr, E.


    The excess proton mobility in water has attracted scientific attention for more than a century. Detailed theoretical concepts and models are also presently in strong focus in efforts toward understanding this ubiquitous phenomenon. In the present report, we discuss a theoretical framework...... for rationalizing the excess proton mobility, based on computer simulations, theory of proton transfer (PT) in condensed media, and analysis of classical proton conductivity experiments over broad temperature ranges. The mechanistic options involved are (i) classical hydrodynamic motion of the hydronium ion (H3O......+), (ii) proton transfer from hydronium to a neighboring water molecule, and (iii) structural diffusion of the Zundel complex (H5O2+), the processes all controlled by orientational fluctuations or hydrogen bond breaking in neighboring hydration shells. Spontaneous conversion of excess proton states...

  20. Comparison of CBS-QB3, CBS-APNO, G2, and G3 thermochemical predictions with experiment for formation of ionic clusters of hydronium and hydroxide ions complexed with water

    Pickard, Frank C.; Pokon, Emma K.; Liptak, Matthew D.; Shields, George C.


    The GAUSSIAN 2, GAUSSIAN 3, complete basis set-QB3, and complete basis set-APNO methods have been used to calculate ΔH° and ΔG° values for ionic clusters of hydronium and hydroxide ions complexed with water. Results for the clusters H3O+(H2O)n and OH-(H2O)n, where n=1-4 are reported in this paper, and compared against experimental values contained in the National Institutes of Standards and Technology (NIST) database. Agreement with experiment is excellent for the three ab initio methods for formation of these clusters. The high accuracy of these methods makes them reliable for calculating energetics for the formation of ionic clusters containing water. In addition this allows them to serve as a valuable check on the accuracy of experimental data reported in the NIST database, and makes them useful tools for addressing unresolved issues in atmospheric chemistry.

  1. Molecular and negative ion production by a standard electron cyclotron resonance ion source.

    Rácz, R; Biri, S; Juhász, Z; Sulik, B; Pálinkás, J


    Molecular and negative ion beams, usually produced in special ion sources, play an increasingly important role in fundamental and applied atomic physics. The ATOMKI-ECRIS is a standard ECR ion source, designed to provide highly charged ion (HCI) plasmas and beams. In the present work, H(-), O(-), OH(-), O(2)(-), C(-), C(60)(-) negative ions and H(2)(+), H(3)(+), OH(+), H(2)O(+), H(3)O(+), O(2)(+) positive molecular ions were generated in this HCI-ECRIS. Without any major modification in the source and without any commonly applied tricks (such as usage of cesium or magnetic filter), negative ion beams of several μA and positive molecular ion beams in the mA range were successfully obtained.

  2. catena-Poly[[tetraaquanickel(II]-μ3-benzene-1,3,5-tricarboxylato-3′:1:2-κ4O1:O3,O3′:O5-[tetraaquanickel(II]-μ2-benzene-1,3,5-tricarboxylato-2:3κ2O1:O3-[tetraaquanickel(II

    Shih-Chen Hsu


    Full Text Available The microwave solvothermal reaction of nickel nitrate with trimesic acid provided the title compound, [Ni3(BTC2(H2O12]n (BTC = benzene-1,3,5-tricarboxylate anion, C9H3O6, which is a metal coordination polymer composed of one-dimensional zigzag chains. The crystal under investigation was ramecically twinned with an approximate twin domain ratio of 1:1. In the asymmetric unit, there are two types of Ni atoms. One of the NiO6 groups (2 symmetry is coordinated to only one carboxylate group and thus terminal, the other is bridging, forming the coordination polymer. The extended chains are connected by the organic BTC anions via μ2-linkages. O—H...O hydrogen bonds and π–π interactions between the chains [centroid–centroid distance 3.58 (1 Å] induce the complex to mimic a three-dimensional structure.

  3. Electrical Mobility of Protons and Proton-Holes in Pure Water Characterized by Physics-Based Water Model

    Jie, Binbin; Sah, Chihtang

    Pure water has been characterized empirically for nearly a century, as dissociation into hydronium (H3O)1+ and hydroxide (HO)1- ions. Last March, we reported that the ~40 year experimental industrial standard of chemical equilibrium reaction constant, the ion product, can be accounted for by a statistical-physics-based concentration product of two electrical charge carriers, the positively charged protons, p+, and the negatively charged proton holes or prohols, p-, with a thermal activation energy or proton trapping well depth of Ep + / p - = 576 meV, in the 0-100OC pure liquid water. We now report that the empirically fitted industrial standard experimental data (1985, 1987, 2005) of the two dc ion mobilities in liquid water, can also be accounted for by trapping-limited drift of protons and prohols through proton channels of lower proton electrical potential valleys, Ep+/0 Pauling statistical model using the 1933 Bernal-Fowler water rule.

  4. Crystal structure of levomepromazine maleate

    Gyula Tamás Gál


    Full Text Available The asymmetric unit of the title salt, C19H25N2OS+·C4H3O4− [systematic name: (S-3-(2-methoxyphenothiazin-10-yl-N,N,2-trimethylpropanaminium hydrogen maleate], comprises two (S-levomepromazine cations and two hydrogen maleate anions. The conformations of the two cations are similar. The major difference relates to the orientation of the methoxy substituent at the phenothiazine ring system. The crystal components form a three-dimensional supramolecular network via N—H...O, C—H...O and C—H...π interactions. A comparison of the conformations of the levomepromazine cations with those of the neutral molecule and similar protonated molecules reveals significant conformational flexibility of the phenothiazine ring system and the substituent at the phenothiazine N atom.

  5. Crystal structure of 2-hydroxy-N-(2-hydroxyethyl-N-{2-hydroxy-3-[(E-N-hydroxyethanimidoyl]-5-methylbenzyl}ethanaminium acetate monohydrate

    Gary S. Nichol


    Full Text Available The structure of the title hydrated molecular salt, C14H23N2O4+·C2H3O2−·H2O, was determined as part of a wider study on the use of the molecule as a polydentate ligand in the synthesis of MnIII clusters with magnetic properties. The cation features intramolecular O—H...N and N—H...O hydrogen-bond interactions. The crystal structure features a range of intermolecular hydrogen-bonding interactions, principally O—H...O interactions between all three species in the asymmetric unit. An R24(8 graph-set hydrogen-bonding motif between the anion and water molecules serves as a unit which links to the cation via the diethanolamine group. Each O atom of the acetate anion accepts two hydrogen bonds.

  6. 内部EGR对HCCI燃烧及自由离子生成影响的数值研究%A Numerical Study on the Effects of Internal EGR on HCCI Combustion and Free Ion Formation

    张志永; 董光宇; 邓俊; 李理光



  7. Kagome-type isostructural 3D-transition metal fluorosulfates with spin 3/2 and 1: synthesis, structure and characterization.

    Marri, Subba R; Kumar, Jitendra; Panyarat, Kitt; Horike, Satoshi; Behera, J N


    Two isostructural transition metal fluorosulfates based on Co and Ni metal ions with the molecular composition of [H3O][M(SO4)F] (where M = Co((II)) for 1 and Ni((II)) for 2) were synthesized under solvothermal conditions and structurally characterized by single crystal X-ray analysis. The materials were further characterized by complementary techniques like TGA, FTIR and PXRD. The 3D-crystal lattice consists of a kagome-type entity where sulfate groups replaced one of the metal nodes when compared with true kagome structures. Magnetic studies of the complexes were also performed which showed that the interactions at the metal center are antiferromagnetic in nature. The proton conductivity increases with the increase in humidity and was found to be 7.9 × 10(-6) S cm(-1) for 2 at RH = 98%.

  8. Poly[aqua(μ-vinylphosphonatocadmium

    Laura K. Byington Congiardo


    Full Text Available The title compound, [Cd(C2H3O3P(H2O]n, was obtained from vinylphosphonic acid and cadmium nitrate. The vinyl groups project into the interlamellar space and the structure is held together via van der Waals forces. The Cd2+ ion is six-coordinate and the geometry is best described as distorted octahedral, with O—Cd—O angles falling within the range 61.72 (13–101.82 (14°. Five of the coordinated oxygen atoms originate from the phosphonate group and the sixth from a bound water molecule. Cd—O distances lie between 2.220 (3 and 2.394 (2 Å. The water molecule is hydrogen bonded to a phosphonate oxygen atom.

  9. Enhanced etching of silicon didioxide guided by carbon nanotubes in HF solution

    Zhao Hua-Bo; Ying Alex Yi-Qun; Yan Feng; Wei Qin-Qin; Fu Yun-Yi; Zhang Yan; Li Yan; Wei Zi-Jun; Zhang Zhao-Hui


    This paper describes a new method to create nanoscale SiO2 pits or channels using single-walled carbon nanotubes (SWNTs) in an HF solution at room temperature within a few seconds.Using aligned SWNT arrays,a pattern of nanoscale SiO2 channels can be prepared.The nanoscale SiO2 patterns can also be created on the surface of three dimensional (3D) SiO2 substrate and even the nanoscale trenches can be constructed with arbitrary shapes.A possible mechanism for this enhanced etching of SiO2 has been qualitatively analysed using defects in SWNTs,combined with H3O+ electric double layers around SWNTs in an HF solution.

  10. Temperature and isotope effects on water cluster ions with path integral molecular dynamics based on the fourth order Trotter expansion

    Suzuki, Kimichi; Shiga, Motoyuki; Tachikawa, Masanori


    Path integral molecular dynamics simulation based on the fourth order Trotter expansion has been performed to elucidate the geometrical isotope effect of water dimer anions, H3O2-, D3O2-, and T3O2-, at different temperatures from 50 to 600 K. At low temperatures below 200 K the hydrogen-bonded hydrogen nucleus is near the center of two oxygen atoms with mostly O⋯X⋯O geometry (where X =H, D, or T), while at high temperatures above 400 K, hydrogen becomes more delocalized, showing the coexistence between O⋯X-O and O-X⋯O. The OO distance tends to be shorter as the isotopomer is heavier at low temperatures, while this ordering becomes opposite at high temperatures. It is concluded that the coupling between the OO stretching mode and proton transfer modes is a key to understand such a temperature dependence of a hydrogen-bonded structure.

  11. 土木香化学成分的研究%Study on the Chemical Components of the Inula helenium

    赵永明; 张嫚丽; 霍长虹; 顾玉诚; 史清文


    采用硅胶柱色谱、制备薄层色谱、制备高效液相、葡聚糖凝胶Sephadex LH-20等方法进行分离纯化,根据光谱数据进行结构鉴定.从乙醇提取物中分离得到了8个化合物,分别鉴定为:异土木香内酯(1),11,13-二氢异土木香内酯(2),土木香内酯(3),β-谷甾醇(4),3-hydroxy-11,13-dihydmisoalantolactone(5),macrophyllilac-tone E(6),urs-12-en-18-H-3-O-β-D-glucopyranoside(7),caffeic acid anhydride(8).化合物7和8系首次从该属植物中分离得到.

  12. Enantiomerically pure (1S,5R) and racemic 3-(1-benzothiophen-2-yl)-8-azoniabicyclo 3.2.1 oct-2-ene acetate

    Frostrup, B.; Peters, D.; Bond, A. D.


    The title compound, C15H16NS+center dot C2H3O2-, has been crystallized as both a pure enantiomer (1S,5R) and a racemate. The racemate crystallizes in the space group Cc, with molecules of opposite handedness related to each other by the action of the c-glide. The enantiomer is essentially...... isostructural with the racemate, except that the glide symmetry is violated by interchange of CH and CH2 groups within the seven-membered ring. The space-group symmetry is reduced to P1 with two molecules in the asymmetric unit. The enantiomer structure shows disorder of the thiophene ring for one...... of the molecules in the asymmetric unit. The major component of the disorder has the thiophene ring in the same position as in the racemate, but generates a higher-energy molecular conformation. The minor disorder component has different intermolecular interactions but retains a more stable molecular conformation....

  13. catena-Poly[[[pentaaquaeuropium(III]-μ-5-sulfonatoisophthalato-κ4O1,O1′:O3,O3′] 4,4'-bipyridine N,N′-dioxide hemisolvate trihydrate

    Ai-Zhi Wu


    Full Text Available In the crystal structure of the title compound, {[Eu(C8H3O7S(H2O5]·0.5C10H8N2O2·3H2O}n, the EuIII coordination polymer displays a ribbon motif as the 5-sulfoisopthalate anion uses one of carboxyl –CO2 units to chelate to a Eu atom and the other to bind to other two Eu atoms; the sulfonyl –SO3 unit is not involved in coordination. Adjacent ribbons are linked by O—H...O hydrogen bonds, generating a three-dimensional network. The 4,4′-bipyridine-N,N′-dioxide molecule lies on an inversion centre and is hydrogen-bonded to the complex network. The coordination geometry of the Eu atom is a monocapped square antiprism.

  14. Atmospheric processes on ice nanoparticles in molecular beams

    Michal eFárník


    Full Text Available This review summarizes some recent experiments with ice nanoparticles (large water clusters in molecular beams and outlines their atmospheric relevance: (1 Investigation of mixed water–nitric acid particles by means of the electron ionization and sodium doping combined with photoionization revealed the prominent role of HNO3 molecule as the condensation nuclei. (2 The uptake of atmospheric molecules by water ice nanoparticles has been studied, and the pickup cross sections for some molecules exceed significantly the geometrical sizes of the ice nanoparticles. (3 Photodissociation of hydrogen halides on water ice particles has been shown to proceed via excitation of acidically dissociated ion pair and subsequent biradical generation and H3O dissociation. The photodissociation of CF2Cl2 molecule in clusters is also mentioned. Possible atmospheric consequences of all these results are briefly discussed.

  15. Density Functional Theory Study on La Complex with Schiff-base as Building Block

    XIA Shu-Wei; XU Xiang; SUN Ya-Li; FAN Yu-Hua; BI Cai-Feng; ZHANG Dong-Mei; YANG Li-Rong


    Quantum density functional theory (DFT) results are reported for the building block [LaL1(NO3)]- of La complex [LaL1(NO3)]NO3·5H2O (L1 = (CH3)2CHCH2CH(NCHC4H3O)COO-). The structure was optimized and the calculation results show that the lanthanum ion is coordinated by one nitrogen atom and three oxygen atoms of L1 and two oxygen atoms of nitrate ion. The bond length of La-N is 0.2637 nm and the average length of La-O is 0.2526 nm, which are consistent with the literatures. In addition, the stabilities, electronic structural characteristics and IR spectra of the complex have been analyzed, which describe the coordination of lanthanum ion with other atoms in detail.

  16. Poly[tetra-n-butylammonium [(μ5-benzene-1,3,5-tricarboxylato(μ4-benzene-1,3,5-tricarboxylato-μ3-hydroxido-trizincate] 0.25-hydrate

    Xiao-Hong Zhu


    Full Text Available In the asymmetric unit of title coordination polymer, {(C16H36N[Zn3(C9H3O62(OH]·0.25H2O}n, there are three independent Zn2+ cations, two benzene-1,3,5-tricarboxylate ligands and a μ3-bridging hydroxide group, together with a tetra-n-butylammonium counter-cation and a partially occupied water molecule of solvation (occupancy 0.25. Each Zn ion is coordinated by three carboxylate O atoms and one O atom from the bridging hydroxide ion, displaying a slightly distorted tetrahedral stereochemistry [overall Zn—O range = 1.875 (3–1.987 (2 Å]. An intramolecular hydrogen bond involving the hydroxide H atom and a carboxylate O-atom acceptor is also present in the complex unit. The bridging benzene-1,3,5-tricarboxylate anions generate a three-dimensional framework structure.

  17. Sensitive detection of n-alkanes using a mixed ionization mode proton-transfer-reaction mass spectrometer

    Amador-Muñoz, Omar; Misztal, Pawel K.; Weber, Robin; Worton, David R.; Zhang, Haofei; Drozd, Greg; Goldstein, Allen H.


    Proton-transfer-reaction mass spectrometry (PTR-MS) is a technique that is widely used to detect volatile organic compounds (VOCs) with proton affinities higher than water. However, n-alkanes generally have a lower proton affinity than water and therefore proton transfer (PT) by reaction with H3O+ is not an effective mechanism for their detection. In this study, we developed a method using a conventional PTR-MS to detect n-alkanes by optimizing ion source and drift tube conditions to vary the relative amounts of different primary ions (H3O+, O2+, NO+) in the reaction chamber (drift tube). There are very few studies on O2+ detection of alkanes and the mixed mode has never been proposed before. We determined the optimum conditions and the resulting reaction mechanisms, allowing detection of n-alkanes from n-pentane to n-tridecane. These compounds are mostly emitted by evaporative/combustion process from fossil fuel use. The charge transfer (CT) mechanism observed with O2+ was the main reaction channel for n-heptane and longer n-alkanes, while for n-pentane and n-hexane the main reaction channel was hydride abstraction (HA). Maximum sensitivities were obtained at low E / N ratios (83 Td), low water flow (2 sccm) and high O2+ / NO+ ratios (Uso = 180 V). Isotopic 13C contribution was taken into account by subtracting fractions of the preceding 12C ion signal based on the number of carbon atoms and the natural abundance of 13C (i.e., 5.6 % for n-pentane and 14.5 % for n-tridecane). After accounting for isotopic distributions, we found that PT cannot be observed for n-alkanes smaller than n-decane. Instead, protonated water clusters of n-alkanes (M ṡ H3O+) species were observed with higher abundance using lower O2+ and higher water cluster fractions. M ṡ H3O+ species are probably the source for the M + H+ species observed from n-decane to n-tridecane. Normalized sensitivities to O2+ or to the sum of O2++ NO+ were determined to be a good metric with which to

  18. Hexa-μ2-acetato-κ12O:O′-μ3-oxido-tris[aquachromium(III] nitrate acetic acid solvate

    Seik Weng Ng


    Full Text Available In the crystal structure of the title salt, [Cr3(C2H3O26O(H2O3]NO3·CH3CO2H, the trinuclear [Cr3(CH3CO26O(H2O3] cluster cation has an oxide O atom that is connected to three water-coordinated CrIII atoms, the three metal atoms forming the points of an equilateral triangle. Each of the six acetate carboxylate groups bridges a Cr–O–Cr fragment. The cluster cation interacts with the nitrate counter-ion and solvent molecules through O—H...O hydrogen bonds, forming a three-dimensional hydrogen-bonded network.

  19. Effect of ditching operations on stream-water chemistry in a boreal forested catchment.

    Aström, M; Aaltonen, E K; Koivusaari, J


    The effects of ditching of boreal forest land on stream-water quality and quantity was assessed by comparing, over a 4-year-period, the physicochemical properties of the water in two small streams (western Finland), one whose catchment was ditched for forestry halfway through the sampling period and another nearby (control) stream whose catchment was not ditched ('paired catchment method'). While the artificial drainage did not have any significant effect on the hydrograph, it resulted in an increase in the aquatic concentrations of Mn, Ca, Mg, suspended material and alkalinity, a decrease in the concentrations of TOC and H3O+, while for Al and Fe there was a change in control mechanisms. The concentration and control changes after ditching are related to changes in hydrological pathways and to the exposure of both organic (peat) and inorganic (mineral soil) layers on the ditch slopes.

  20. Cassini detection of Enceladus' cold water-group plume ionosphere

    Tokar, R. L.; Johnson, R. E.; Thomsen, M. F.; Wilson, R. J.; Young, D. T.; Crary, F. J.; Coates, A. J.; Jones, G. H.; Paty, C. S.


    This study reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier water dimer ions (HxO2)+ very close to Enceladus where the plasma begins to emerge from the plume. The data were obtained during two close (52 and 25 km) flybys of Enceladus in 2008 and are similar to ion data in cometary comas. The ions are observed in detectors looking in the Cassini ram direction exhibiting energies consistent with the Cassini speed, indicative of a nearly stagnant plasma flow in the plume. North of Enceladus the plasma slowing commences about 4 to 6 Enceladus radii away, while south of Enceladus signatures of the plasma interaction with the plume are detected 22 Enceladus radii away.

  1. Diffusion-Oscillatory Dynamics in Liquid Water on Data of Dielectric Spectroscopy

    Volkov, A A; Volkov, A A; Sysoev, N N


    When analyzing the broadband absorption spectrum of liquid water (10^10 - 10^13 Hz), we find its relaxation-resonance features to be an indication of Frenkel's translation-oscillation motion of particles, which is fundamentally inherent to liquids. We have developed a model of water structure, of which the dynamics is due to diffusion of particles, neutral H2O molecules and H3O+ and OH- ions - with their periodic localizations and mutual transformations. This model establishes for the first time a link between the dc conductivity, the Debye and the high frequency sub-Debye relaxations and the infrared absorption peak at 180 cm-1. The model reveals the characteristic times of the relaxations, 50 ps and 3 ps, as the lifetimes of water molecules and water ions, respectively. The model sheds light on the anomalous mobility of a proton and casts doubt on the long lifetime of a water molecule, 10 hours, commonly associated with autoionization.

  2. Proton-conducting beta"-alumina via microwave-assisted synthesis and mechanism of enhanced corrosion prevention of a zinc rich coating with electronic control

    Kirby, Brent William

    Proton Conducting beta-alumina via Microwave Assisted Synthesis. The microwave assisted synthesis of proton conducting Mg- and Li-stabilized NH4+/H3O+ beta-alumina from a solution based gel precursor is reported. beta-alumina is a ceramic fast ion conductor containing two-dimensional sheets of mobile cations. Na +-beta-alumina is the most stable at the sintering temperatures (1740°C) reached in a modified microwave oven, and can be ion exchanged to the K+ form and then to the NH4+/H 3O+ form. beta-phase impurity is found to be 20% for Mg-stabilized material and 30-40% for Li-stabilized material. The composition of the proton conducting form produced here is deficient in NH4 + as compared to the target composition (NH4)1.00 (H3O)0.67Mg0.67Al10.33O 17. Average grain conductivity for Li-stabilized material at 150°C is 6.6x10-3 +/- 1.6x10-3 S/cm with 0.29 +/- 0.05 eV activation energy, in agreement with single crystal studies in the literature. Grain boundary conductivity is found to be higher in the Li-stabilized material. A hydrogen bond energy hypothesis is presented to explain these differences. Li-stabilized NH4+/H3O + beta-alumina is demonstrated as a fuel cell electrolyte, producing 28 muA/cm2 of electrical current at 0.5 V. Mechanism of Enhanced Corrosion Prevention of a Zinc Rich Coating with Electronic Control. A corrosion inhibition system consisting of high weight-loading zinc rich coating applied to steel panels is examined. An electronic control unit (ECU) consisting of a battery and a large capacitor in series with the panel is shown to improve corrosion protection upon immersion in 3% NaCl solution. Weekly solution changes to avoid zinc saturation in solution system were necessary to see well differentiated results. The corrosion product, hydrozincite [Zn5(CO3) 2(OH)6] is observed to deposit within the pores of the coating and on the surface as a barrier layer. Simonkolleite [Zn5(OH) 8Cl2·H2O] is found to form in place of the original zinc particles

  3. Electrochemical characteristics and impedance spectroscopy studies of nano-cobalt silicate hydroxide for supercapacitor

    Zhang, Guo-Qing; Zhao, Yong-Qing; Tao, Feng; Li, Hu-Lin

    Cobalt silicate hydroxide (Co 3[Si 2O 5] 2[OH] 2) was prepared by chemical method for use in electrochemical capacitors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests indicate that the material was pure hexagonal phase with uniform nanometer size distribution. Cyclic voltammeter (CV) and galvanostatic charge/discharge measurements show that the cobalt silicate hydroxide-based electrode has stable electrochemical capacitor properties between potential range of 0.1-0.55 V with a maximum specific capacitance of 237 F g -1 in alkaline solution and 95% of capacity efficiency was reached after 150 cycles. Electrochemical impedance spectra (EIS) investigation illustrates that the capacitance of the test electrode was mainly consisted of pseudo-capacitance, which was caused by underpotential deposition of H 3O + at the electrode surface.




    Full Text Available The alkali bond in (N, K–A–S–H gels presents an up-to-date insufficiently resolved issue with significant consequences for efflorescence in alkali-activated materials. A series of experiments shows nearly all alkalis are leachable from alkaliactivated fly-ash and metakaolin in excessive amounts of deionized water. A diffusion-based model describes well the alkali leaching process. Negligible changes of the (N, K–A–S–H gel nanostructure indicate that Na,K do not form the gel backbone and H3O+ is probably the easiest substitution for the leached alkalies. Small changes in the long-term compressive strength of leached specimens support this hypothesis.

  5. A Novel Hydrogen-bonded Three-dimensional Network Complex Containing Nickel

    WANG Li; LI Juan; WANG En-bo


    A novel complex, (H3O)2[Ni(2,6-pydc)2] · 2H2O was synthesized in an aqueous solution and characterized by means of single-crystal X-ray diffraction, elemental analyses and IR spectra. The X-ray structural analysis revealed that the novel compound forms three-dimensional(3D) networks by both π-π stacking and hydrogen-bonding interactions. The crystal data for the complex are a = 13. 853 (3) nm, b= 9. 6892 (19) nm,c=13.732(3) nm, α=90. 00°, β=115.52(3)°, γ=90.00°, Z=3, R1=0. 0786, wR2=0.1522.

  6. Bis[μ-2-(2,4-difluorophenyl-1,3-bis(1,2,4-triazol-1-ylpropan-2-olato-κ4N2,O:O,N2′]bis[(acetato-κ2O,O′nickel(II] methanol hemisolvate

    Feng Zhang


    Full Text Available In the title complex, [Ni2(C13H11F2N6O2(C2H3O22]·0.5CH3OH, there are two half-molecules in the asymmetric unit. The two centrosymmetrically related NiII atoms, each attached to an acetate ligand, are linked by two fluconazole ligands. Each NiII atom is six-coordinated in a distorted octahedral geometry by two N atoms of the triazole groups and two bridging O atoms from two different fluconazole ligands and two O atoms from a chelating acetate ligand. In the crystal structure, the half-occupied methanol solvent molecule is linked to a triazole group via an O—H...N hydrogen bond.

  7. Synthesis and Characterization of a New Triple-layered Perovskite KSr2Nb3O10 and Its Protonated Compounds


    New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2Nb3O10*1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction.These new compounds were characterized by EPMA,AAS,XRD,IR,DTA and so on.The structure may be described as treble perovskite sheets [Sr2Nb3O10]- interleaved with K+,H3O+ or H+.These new compounds are new members of the Dion-Jacobsonseries with n=3 for the general formula M[An-1NbnO3n+1],and their indexed X-ray powder diffraction data were first reported in the paper.

  8. Effects Of Electrons and Heavy Particles On Halpha Emission In Pure H2O DC Discharge At High E/N (E-Electric Field, N-Gas Density)

    Petrovic, Zoran; Stojanovic, Vladimir; Skoro, Nikola; Sivos, Jelena; Maric, Dragana; Malovic, Gordana


    In this work we present results of Monte Carlo simulations for spatially resolved emission due to the transport of electrons and heavy particles (fast H, H+, OH+, H2O+,H3O+) in pure H2O for the conditions used in plasma assisted technologies. Monte Carlo technique, already used for similar discharges in nitrogen, argon and hydrogen is used to obtain spatially resolved Halpha emission in H2O. Data for anisotropic scattering of electrons, ions and fast neutrals are used to obtain contribution to Halpha spatially resolved emission. Agreement with experimental data for drift velocities for all charged particles and effective electron ionization for the conditions of moderate E/N allowed us to study production of heavy particles and subsequently spatial emission as a consequence of their transport. Acknowledgment to Ministry of Education, Science and Technology of Republic Serbia, Projects No. 171037 and 410011.

  9. Hydrothermal Synthesis and Structure of [{Mo8V4O36 (VO4) (VO)2 }n]7n-Bi-capped α-Keggin Fragments Linked to a Chain


    The title compound, (H2en) 3H3O { MosV4O36 (VO4) (VO) 2 } · 4H2O, was hydrothermally synthesized and structurally characterized by means of IR, ESR spectrum and single crystal X-ray diffraction. It crystallized in a monoclinic system with space group P21/c, a= 1. 980 4(4)nm, b=2. 063 4(4) nm, c=1. 192 0(2) nm, β=94. 76(3)°and deep black colour. The compound contains V-centered bi-capped a-Keggin fragments { MosV7O42 } that are linked together by edge-shared units V ⅣO5 via V-O-V bonds, forming a chain.

  10. Secondary organic material formed by methylglyoxal in aqueous aerosol mimics – Part 2: Product identification using Aerosol-CIMS

    V. F. McNeill


    Full Text Available We used chemical ionization mass spectrometry with a volatilization flow tube inlet (Aerosol-CIMS to characterize secondary organic material formed by methylglyoxal with ammonium sulfate in aqueous aerosol mimics. Bulk reaction mixtures were diluted and atomized to form submicron aerosol particles. Organics were detected using Aerosol-CIMS in positive and negative ion mode using I− and H3O+·(H2On as reagent ions. The results are consistent with aldol condensation products, carbon-nitrogen species, sulfur-containing compounds, and oligomeric species up to 759 amu. These results support previous observations by us and others that ammonium sulfate plays a critical role in the SOA formation chemistry of dicarbonyl compounds.

  11. Di-μ-acetato-μ-aqua-bis­[acetatobis(1H-benzimidazole)cobalt(II)

    Zimmermann, Iwan; Keene, Tony D.; Neels, Antonia; Decurtins, Silvio


    In the title compound, [Co2(C2H3O2)4(C7H6N2)4(H2O)], the half-mol­ecule in the asymmetric unit is completed by a crystallographic twofold rotation axis to give the full mol­ecule. The CoII ions are approximately octahedrally coordinated with a cis-N2O4 coordination sphere. The compound features intra­molecular O—H⋯O hydrogen bonds between the non-bridging acetate groups and the bridging water mol­ecule, and inter­molecular N—H⋯O hydrogen bonds between the acetates and amine H atoms of the benzimidazoles which determine the mol­ecular packing in the crystal structure. PMID:21202524

  12. Di-μ-acetato-μ-aqua-bis-[acetatobis(1H-benzimidazole)cobalt(II)].

    Zimmermann, Iwan; Keene, Tony D; Neels, Antonia; Decurtins, Silvio


    In the title compound, [Co(2)(C(2)H(3)O(2))(4)(C(7)H(6)N(2))(4)(H(2)O)], the half-mol-ecule in the asymmetric unit is completed by a crystallographic twofold rotation axis to give the full mol-ecule. The Co(II) ions are approximately octahedrally coordinated with a cis-N(2)O(4) coordination sphere. The compound features intra-molecular O-H⋯O hydrogen bonds between the non-bridging acetate groups and the bridging water mol-ecule, and inter-molecular N-H⋯O hydrogen bonds between the acetates and amine H atoms of the benzimidazoles which determine the mol-ecular packing in the crystal structure.

  13. Hydrogen bonding: a channel for protons to transfer through acid-base pairs.

    Wu, Liang; Huang, Chuanhui; Woo, Jung-Je; Wu, Dan; Yun, Sung-Hyun; Seo, Seok-Jun; Xu, Tongwen; Moon, Seung-Hyeon


    Different from H(3)O(+) transport as in the vehicle mechanism, protons find another channel to transfer through the poorly hydrophilic interlayers in a hydrated multiphase membrane. This membrane was prepared from poly(phthalazinone ether sulfone kentone) (SPPESK) and H(+)-form perfluorosulfonic resin (FSP), and poorly hydrophilic electrostatically interacted acid-base pairs constitute the interlayer between two hydrophilic phases (FSP and SPPESK). By hydrogen bonds forming and breaking between acid-base pairs and water molecules, protons transport directly through these poorly hydrophilic zones. The multiphase membrane, due to this unique transfer mechanism, exhibits better electrochemical performances during fuel cell tests than those of pure FSP and Nafion-112 membranes: 0.09-0.12 S cm(-1) of proton conductivity at 25 degrees C and 990 mW cm(-2) of the maximum power density at a current density of 2600 mA cm(-2) and a cell voltage of 0.38 V.

  14. 1-(2-Hydroxyethyl-4-{3-[(E-2-(trifluoromethyl-9H-thioxanthen-9-ylidene]propyl}piperazine-1,4-diium bis(3-carboxyprop-2-enoate

    M. S. Siddegowda


    Full Text Available In the title salt, C23H27F3N2OS+·2C4H3O4−, a non-merohedral twin [ratio of the twin components = 0.402 (1:0.598 (1], the –CF3 group is disordered over two sets of sites with occupancy factors in the ratio 0.873 (2:0.127 (2. The dihedral angle between the two outer aromatic rings of the 9H-thioxanthene unit, whose thiopyran ring has a screw-boat conformation, is 33.01 (9°. The diprotonated piperazine ring adopts a chair conformation. In the crystal, intermolecular O—H...O, N—H...O and C—H...O hydrogen bonds between neighboring molecules form zigzag chains along the a axis and contribute to the stabilization of the packing.

  15. Synthesis, characterization, crystal structure of magnesium compound based 3, 3‧, 5, 5‧-azobenzentetracarboxylic acid and application as high-performance heterogeneous catalyst for cyanosilylation

    Li, Yong-Peng; Zhang, Ling-Juan; Ji, Wen-Juan


    A novel coordination compound with the formula {[H3O]2[Mg(ABTC)(DMI)2]}n (1) (H4ABTC = 3,3‧,5,5‧-azobenzene-tetracarboxylic acid, DMI = 1,3-dimethy-2-imidazolidinone) as synthesized under solvothermal condition and characterized by thermogravimetric analysis, IR spectroscopy, X-ray powder diffraction and single crystal X-ray diffraction. Compound 1 features a novel 3-D anionic framework [Mg(ABTC)(DMI)2]n2n- constructed by linking adjacent 2-D layer with the phenyl rings of the ABTC4- ligands and can be classified as a (4,4)-connected PtS porous net; it also has highly heterogeneous catalysis activity for the cyanosilylation of carbonyl compounds at low loading (0.1 mol%) leading to up to 99% conversion of benzaldehyde under solvent-free conditions. When Mg-abtc MOF (1) was recycled five times, its catalytic activity remained with an inconspicuous decrease.

  16. Water Group Composition Near the Orbit of Enceladus

    Williams, J. D.; Delamere, P. A.; Bagenal, F.; Reisenfeld, D.; Fleshman, R.


    We present magnetospheric ion composition results from the Cassini CAPS IMS instrument. The data set is averaged over a four year period. Data from the equatorial plane are selected and binned into radial, local time and longitude bins with a focus on radial distances between 3-10 Saturn radii. The data analysis process necessitates fitting the instrument response functions to the raw data and so methods of assessment of data uncertainty are also presented. Water group ions (O+, OH+, H2O+, H3O+; or collectively W+), presented as mixing ratios dominate over H+ in this radial range and O+ is the dominant water group species. Temporal variations within the study period are presented. The energy distribution of the ion composition is also examined and the flow velocity is compared to the corotation velocity of the plasma.

  17. Hydrogen bonded complexes of cyanuric acid with pyridine and guanidinium carbonate

    K Sivashankar


    Hydrogen bonded complexes of cyanuric acid (CA) with pyridine, [C3N3H3O3:C5H5N], 1, and guanidinium carbonate [C3H2N3][C(NH2)3], 2, have been prepared at room temperature and characterized by single-crystal X-ray diffraction. Structure of 1 shows pyridine molecules substituting the inter-tape hydrogen bond in CA by N-H…N and C-H…O hydrogen bonds. The structure reveals CA-pyridine hydrogen-bonded single helices held together by dimeric N-H…O hydrogen bonding between CA molecules. In 2, the CA tapes, resembling a sine wave interact with the guanidinium cations through N-H…O and N-H…N hydrogen bonds forming guanidinium cyanurate sheets.

  18. Effect of the reaction conditions on the formation of the ZnO nanostructures

    Perillo, P. M.; Atia, M. N.; Rodríguez, D. F.


    ZnO nanorods were synthesized through a simple chemical method by reacting Zn(C2H3O2)2·2H2O and NaOH at low temperature and the effects of changing the order of addition of reactants on the morphological evolution of ZnO nanorods were investigated. The samples were characterized by using XRD, SEM, EDX, TEM, BET and Raman techniques. Optical properties of the ZnO nanostructures were too investigated by UV-Vis spectroscopy at room temperature. The hexagonal wurtzite phase of ZnO was confirmed by X-ray diffraction (XRD) for all the samples. SEM and TEM analysis indicated that different morphologies were obtained by changing the order of addition of reactants.

  19. cis,cis,cis-(Acetato-κ2O,O′bis[1,2-bis(diphenylphosphanylethane-κ2P,P′]ruthenium(II 0.75-trifluoromethanesulfonate 0.25-chloride

    João Figueira


    Full Text Available In the title RuII carboxylate compound, [Ru(C2H3O2(C26H24P22](CF3O3S0.75Cl0.25, the distorted tris-bidentate octahedral stereochemistry about the RuII atom in the complex cation comprises four P-atom donors from two 1,2-bis(diphenylphosphanylethane ligands [Ru—P = 2.2881 (13–2.3791 (13 Å] and two O-atom donors from the acetate ligand [Ru—O = 2.191 (3 and 2.202 (3 Å]. The disordered counter-anions are located on the same site in the structure in a 3:1 ratio, the expanded formula comprising four complex cations, three trifluoromethanesulfonate anions and one chloride anion, with two such formula units in the unit cell.

  20. Studies on Molecular and Ion Transport in Silicalite Membranes and Applications as Ion Separator for Redox Flow Battery

    Yang, Ruidong

    Microporous zeolite membranes have been widely studied for molecular separations based on size exclusion or preferential adsorption-diffusion mechanisms. The MFI-type zeolite membranes were also demonstrated for brine water desalination by molecular sieving effect. In this research, the pure silica MFI-type zeolite (i.e. silicalite) membrane has been for the first time demonstrated for selective permeation of hydrated proton (i.e. H3O+) in acidic electrolyte solutions. The silicalite membrane allows for permeation of H 3O+ ions, but is inaccessible to the large hydrated multivalent vanadium ions due to steric effect. The silicalite membrane has been further demonstrated as an effective ion separator in the all-vanadium redox flow battery (RFB).The silicalite is nonionic and its proton conductivity relies on the electric field-driven H3O+ transport through the sub nanometer-sized pores under the RFB operation conditions. The silicalite membrane displayed a significantly reduced self-discharge rate because of its high proton-to-vanadium ion transport selectivity. However, the nonionic nature of the silicalite membrane and very small diffusion channel size render low proton conductivity and is therefore inefficient as ion exchange membranes (IEMs) for practical applications. The proton transport efficiency may be improved by reducing the membrane thickness. However, the zeolite thin films are extremely fragile and must be supported on mechanically strong and rigid porous substrates. In this work, silicalite-Nafion composite membranes were synthesized to achieve a colloidal silicalite skin on the Nafion thin film base. The "colloidal zeolite-ionic polymer" layered composite membrane combines the advantages of high proton-selectivity of the zeolite layer and the mechanical flexibility and low proton transport resistance of the ionic polymer membrane. The composite membrane exhibited higher proton/vanadium ion separation selectivity and lower electrical resistance than

  1. Bis(acetato-κ2O,O′bis(3,5-dimethyl-1H-pyrazole-κN2copper(II

    Yuliya M. Davydenko


    Full Text Available In the title compound, [Cu(C2H3O22(C5H8N22], the CuII atom has a distorted tetragonal–bipyramidal geometry, with the equatorial plane formed by two N atoms belonging to two 3,5-dimethyl-1H-pyrazole ligands and two O atoms from two acetate anions. The second O atoms of the acetate groups provide elongated Cu—O axial contacts, so that the acetates appear to be coordinated in a pseudo-chelate fashion. The pyrazole ligands are situated in cis positions with respect to each other. In the crystal structure, molecules are linked through intermolecular N—H...O hydrogen bonds, forming a one-dimensional chain.

  2. Ionization chemistry in the H2O-dominant atmospheres of the icy moons

    Shematovich, V. I.; Johnson, R. E.


    The main pathways of the ionization chemistry for pure H2O- and mixed H2O+O2+CO2+NH3+CH4 atmospheres which are representative for neutral and ionized atmospheres of the icy bodies in the Jovian and Saturnian systems are discussed. The gaseous envelopes of the icy moons of the giant planets are formed usually due to the surface radiolysis by the solar UV radiation and energetic magnetospheric plasma (Johnson, 1990). The standard astrochemical UMIST2005 (UDFA05) network is used to infer the main chemical pathways of ionization chemistry in the pure or with admixtures of other volatile molecules water vapor atmospheres. In case of the H2O- dominant atmosphere the parent H2O molecules are easily dissociated and ionized by the solar UVradiation and the energetic magnetospheric electrons. These impact processes result in the formation of the secondary neutral and ionized products - chemically active radicals O and OH, and H+, H2+, O+, OH+, and H2O+ ions. Secondary ions have admixture abundances in the H2O-dominant atmospheres, because they are efficiently transformed to H3O+ hydroxonium ions in the fast ion-molecular reactions. The major H3O+ hydroxonium ion does not chemically interact with other neutrals, and is destroyed in the dissociative recombination with thermal electrons mainly reproducing the chemically simple H, H2, O, and OH species. In case of the mixed H2O+O2-dominant atmosphere corresponding to the near-surface atmospheres of icy moons (Shematovich et al., 2005), the ionization chemistry results in the formation of the second major ion O2+ - because ion of molecular oxygen has the lower ionization potential comparing with other parent species -H2, H2O, CO2. The H+, O+, OH+, and H2O+ ions can be easily converted to O2+ ions through the ion-molecular reactions. In case of significant admixture of molecular hydrogen it is possible to transfer the O2+ ions to the O2H+ ions through the fast reaction with H2 and further to the H3O+ ions through the ion

  3. Unusual products in the reactions of phosphorus(III) compounds with N=N, C≡C or conjugated double-bonded systems

    K C Kumara Swamy; E Balaraman; K Praveen Kumar; N Satish Kumar


    The diversity of products in the reaction of diethyl azodicarboxylate (DEAD)/diisopropyl azodicarboxylate (DIAD) and activated acetylenes with PIII compounds bearing oxygen or nitrogen substituents is discussed. New findings that are useful in understanding the nature of intermediates involved in the Mitsunobu reaction are highlighted. X-ray structures of two new compounds (2--Bu-4-MeC6H3O)P (-N--Bu)2P+[(NH--Bu){N[(CO2--Pr)(HNCO2--Pr)]}](Cl-)(2--Bu-4-MeC6H3OH) (23) and [CH2(6--Bu-4-Me-C6H2O)2P(O)C(CO2Me)C-(CO2Me)CClNC(O)Cl] (33) are also reported. The structure of 23 is close to one of the intermediates proposed in the Mitsunobu reaction.

  4. Poly[aqua(μ-vinyl-phospho-nato)cadmium].

    Congiardo, Laura K Byington; Mague, Joel T; Funk, Aaron R; Yngard, Ria; Knight, D Andrew


    The title compound, [Cd(C(2)H(3)O(3)P)(H(2)O)](n), was obtained from vinyl-phospho-nic acid and cadmium nitrate. The vinyl groups project into the inter-lamellar space and the structure is held together via van der Waals forces. The Cd(2+) ion is six-coordinate and the geometry is best described as distorted octa-hedral, with O-Cd-O angles falling within the range 61.72 (13)-101.82 (14)°. Five of the coordinated oxygen atoms originate from the phospho-nate group and the sixth from a bound water molecule. Cd-O distances lie between 2.220 (3) and 2.394 (2) Å. The water mol-ecule is hydrogen bonded to a phospho-nate oxygen atom.

  5. Formation of Carbonic Acid in Impact of CO2 on Ice and Water.

    Hirshberg, Barak; Gerber, R Benny


    A new mode of formation is proposed for carbonic acid in the atmosphere. It involves impact of vibrationally excited gas-phase CO2 molecules on water or ice particles. This is a first mechanism that supports formation on ice as well as on liquid water surfaces. Results of ab initio molecular dynamics simulations are presented on collisions of CO2 with (H2O)n clusters (n = 1, 4, 8, 12). Efficient formation of carbonic acid is seen with product lifetimes exceeding 100 ps. The reaction is feasible even for collision of CO2 with a single water molecule but in a different mechanism than for larger clusters. For clusters, the transition state shows charge separation into H3O(+)···HCO3(-), which transforms into neutral carbonic acid as the product, hydrated by the remaining waters. Possible atmospheric implications of the results are discussed.

  6. Communication: The origin of rotational enhancement effect for the reaction of H2O+ + H2 (D2)

    Li, Anyang; Li, Yongle; Guo, Hua; Lau, Kai-Chung; Xu, Yuntao; Xiong, Bo; Chang, Yih-Chung; Ng, C. Y.


    We have measured the absolute integral cross sections (σ's) for H3O+ formed by the reaction of rovibrationally selected H2O+(X2B1; v1+v2+v3+ = 000; N+Ka+Kc+ = 000, 111, and 211) ion with H2 at the center-of-mass collision energy (Ecm) range of 0.03-10.00 eV. The σ(000), σ(111), and σ(211) values thus obtained reveal rotational enhancements at low Ecm reactant ion facilitated by rotational excitation thus promotes the H2O+ + H2 (D2) reaction along the minimum energy pathway, rendering the observed rotational enhancement effects. The occurrence of this effect at low Ecm indicates that the long range charge and dipole-induced-multipole interactions of the colliding pair play a significant role in the dynamics of the exothermic H2O+ + H2 (D2) reactions.

  7. Modeling the Enceladus plume--plasma interaction

    Fleshman, B L; Bagenal, F


    We investigate the chemical interaction between Saturn's corotating plasma and Enceladus' volcanic plumes. We evolve plasma as it passes through a prescribed H2O plume using a physical chemistry model adapted for water-group reactions. The flow field is assumed to be that of a plasma around an electrically-conducting obstacle centered on Enceladus and aligned with Saturn's magnetic field, consistent with Cassini magnetometer data. We explore the effects on the physical chemistry due to: (1) a small population of hot electrons; (2) a plasma flow decelerated in response to the pickup of fresh ions; (3) the source rate of neutral H2O. The model confirms that charge exchange dominates the local chemistry and that H3O+ dominates the water-group composition downstream of the Enceladus plumes. We also find that the amount of fresh pickup ions depends heavily on both the neutral source strength and on the presence of a persistent population of hot electrons.

  8. Gas-phase protonation of pyridine. A variable-time neutralization-reionization and Ab initio study of pyridinium radicals.

    Nguyen, V Q; Turecek, F


    Gas-phase protonation of pyridine with CH3NH3+, NH4+, t-C4H9+, H3O+ and CH5+ under thermal conditions was studied by variable-time neutralization-reionization mass spectrometry and ab initio calculations. N-Protonation was found to occur exclusively for CH3NH3+ through H3O+ and predominantly for CH5+. The calculated MP2/6-311G(2d,p) energies gave the proton affinities of N, C-2, C-3 and C-4 in pyridine as 924, 658, 686 and 637 kJ mol-1, respectively, which were in good agreement with previous experimental and theoretical results. Vertical neutralization of the N-protonated isomer (1H+) was accompanied by moderate Franck-Condon effects that deposited 20-21 kJ mol-1 in the 1H-pyridinium radicals (1H) formed. 1H was calculated by UMP2/6-311G(2d,p) and B3LYP/6-311G(2d,p) to be a bound species in its ground electronic state. A substantial fraction of stable 1H was detected in the spectra, which depended on the precursor ion internal energy. Deuterium labeling showed a specific loss of the N-bound hydrogen or deuterium in the radicals. The specificity increased with increasing internal energy in the radicals and decreasing contribution of ion dissociations following reionization. Variable-time measurements established specific loss of the N-bound deuterium also in dissociating low-energy 1D. Loss of hydrogen from 1H+ cations following reionization was highly endothermic and was accompanied by rearrangements that partially scrambled the ring hydrogens.

  9. Emissions and Chemistry of Volatile Organic Compounds in Early Spring of Western U.S.: Interactions between Oil/Gas Emissions and Biogenic Emissions

    Yuan, B.; Koss, A.; Warneke, C.; Gilman, J.; Lerner, B. M.; Peischl, J.; Ryerson, T. B.; Sjostedt, S. J.; Thompson, C. R.; Wild, R. J.; Brown, S. S.; Neuman, J. A.; Eilerman, S. J.; Wolfe, G. M.; St Clair, J. M.; Hanisco, T. F.; Thayer, M. P.; Keutsch, F. N.; De Gouw, J. A.


    A series of research flights with the NOAA WP-3D aircraft were conducted during the SONGNEX campaign ( to characterize emissions of trace gases from oil and gas basins in the western United States and their chemical transformations. Volatile organic compounds (VOCs) were measured by a newly developed chemical ionization mass spectrometer that uses H3O+ for ionization and a high-resolution time-of-flight mass spectrometer for detection (H3O+ CIMS). Results from the measurements will be presented at the meeting. Emission fluxes of VOCs can be determined both by the mass balance and eddy covariance methods. To investigate the potential for eddy covariance flux measurements, we focus on two flights conducted over the Haynesville shale basin on April 4 and April 25, 2015, respectively. Much higher concentrations of biogenic VOCs (isoprene, monoterpenes and methanol) were measured during the flight on April 25, 2015, which provides an opportunity to evaluate our instrument for the eddy covariance technique. Emissions and deposition of various hydrocarbons and oxygenated VOCs are determined and flux divergence derived from flux estimates at different altitudes is used to explore formation and loss processes of organic species in the boundary layer. Based on results from the eddy covariance technique, we will discuss some implications on distribution of emission strength in an oil/gas basin, i.e. what is the relative importance of high versus low emitters to the total emissions. We will also investigate the roles of biogenic emissions in the chemical evolution of oil and gas emissions by comparing the two flights.

  10. Measurement of low-ppm mixing ratios of water vapor in the upper troposphere and lower stratosphere using chemical ionization mass spectrometry

    T. D. Thornberry


    Full Text Available A chemical ionization mass spectrometer (CIMS instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS. A low-pressure flow of sample air passes through an ionization volume containing an α-particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+ from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument was calibrated every 45 min in flight by introducing a series of H2O mixing ratios between 0.5 and 153 parts per million (ppm, 10−6 mol mol−1 generated by Pt-catalyzed oxidation of H2 standards while overflowing the inlet with dry synthetic air. The CIMS H2O instrument was deployed in an unpressurized payload area aboard the NASA WB-57F high-altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX mission in March and April 2011. The instrument performed successfully during seven flights, measuring H2O mixing ratios below 5 ppm in the lower stratosphere at altitudes up to 17.7 km, and as low as 3.5 ppm near the tropopause. Data were acquired at 10 Hz and reported as 1 s averages. In-flight calibrations demonstrated a typical sensitivity of 2000 Hz ppm−1 at 3 ppm with a signal to noise ratio (2 σ, 1 s greater than 32. The total measurement uncertainty was 9 to 11%, derived from the uncertainty in the in situ calibrations.

  11. Unimolecular and hydrolysis channels for the detachment of water from microsolvated alkaline earth dication (Mg2+, Ca2+, Sr2+, Ba2+) clusters

    Miliordos, Evangelos; Xantheas, Sotiris S.


    We examine theoretically the three channels that are associated with the detachment of a single water molecule from the aqueous clusters of the alkaline earth dications, [M(H2O)n]2+, M = Mg, Ca, Sr, Ba, n ≤ 6. These are the unimolecular water loss (M2+(H2O)n-1 + H2O) and the two hydrolysis channels resulting to the loss of hydronium ([MOH(H2O)n-2]+ + H3O+) and Zundel ([MOH(H2O)n-3]+ + H3O+(H2O)) cations. The Potential Energy Curves (PECs) corresponding to those three channels were constructed at the Møller-Plesset second order perturbation (MP2) level of theory with basis sets of double- and triple-ζ quality. We furthermore investigated the water and hydronium loss channels from the mono-hydroxide water clusters with up to four water molecules, [MOH(H2O)n]+, 1 ≤ n ≤ 4. Our results indicate the preference of the hydronium loss and possibly the Zundel cation loss channels for the smallest size clusters, whereas the unimolecular water loss channel is preferred for the larger ones as well as the mono-hydroxide clusters. Although the charge separation (hydronium and Zundel cation loss) channels produce more stable products when compared to the ones for the unimolecular water loss, they also require the surmounting of high energy barriers, a fact that makes the experimental observation of fragments related to these hydrolysis channels difficult.

  12. Crystal structure of bis-[(acetato-κO)(imidazolidine-2-thione-κS)bis-(tri-phenyl-phosphane-κP)silver(I)] di-μ-imidazol-idine-2-thione-κ(4) S:S-bis-[(imidazol-id-ine-2-thione-κS)bis-(tri-phenyl-phosphane-κP)silver(I)] di-acetate aceto-nitrile disolvate tetra-hydrate.

    Nimthong-Roldán, Arunpatcha; Ratthiwan, Janejira; Lakmas, Sawanya; Wattanakanjana, Yupa


    In the title compound, [Ag2(C3H6N2S)4(C18H15P)2](C2H3O2)2·[Ag(C2H3O2)(C3H6N2S)(C18H15P)2]2·2C2H3N·4H2O, the Ag(I) ion in the mononuclear neutral complex exhibits a distorted tetra-hedral environment with coordination by two P atoms from tri-phenyl-phosphane (PPh3) ligands, one S atom of an imidazolidine-2-thione (etu) ligand and one O atom of an acetate anion. The binuclear cationic complex comprises two inversion-related [Ag(C3H6N2S)2(C18H15P)] units with Ag(I) ions bridged by two S atoms from etu ligands forming a four-membered Ag-S-Ag-S ring. Each Ag(I) ion is coordinated by a P atom of a PPh3 ligand, two S atoms of bridging etu ligands and the terminal S atom of an etu ligand in a distorted tetra-hedral environment. In the crystal, the mononuclear complex is linked to lattice water mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds, forming a chain along [100]. In addition, the binuclear complex mol-ecules are connected to acetate anions and lattice water mol-ecules via O-H⋯O, N-H⋯O and O-H⋯S hydrogen bonds, also along [100].

  13. Peculiarities of the Growth and Photosynthetic Pigments Content in Algaeculture of Acutodesmus dimorphus (Tupin P.M. Tsarenko under Salt and Acetate Stresses

    K.O. Romanenko


    Full Text Available The objective of this research was to investigate the effect of salt (NaCl and acetate (NaC2H3O2 stresses on the pattern of biomass accumulation and photosynthetic pigments content in algae culture of the freshwater green alga Acutodesmus dimorphus (Turpin P.M. Tsarenko IBASU-A 251. We demonstrated that sodium chloride introduced in a culture medium at various concentrations caused a gradual reduction of the microalga biomass whose maximum was recorded at the salt concentration of 1.5%. Addition of sodium acetate at the same concentrations led, on the contrary, to a sharp (more than two times decrease of A. dimorphus biomass. On the 18th day of culturing under salt stress conditions the chlorophyll a content decreased 1.5-2.5 times, the chlorophyll b content – 1.3-1.7 times, while the carotenoids quantity increased 1.2-1.6 times. Under acetate stress conditions the chlorophyll a content decreased 2-3 times, that of chlorophyll b – 1.7 – 1.8 times whereas the carotenoids quantity increased within the range of 1.4-1.8 times. Increase in chemical stressors concentrations involved some reduction of the chlorophylls а/b ratio and total chlorophylls а+b content, and at the same time, the ratio carotenoids/a+b increased. Sodium acetate appeared to be a more powerful inducer of carotinogenesis than sodium chloride. The highest quantity of carotenoids was registered at 1% and 1.5% concentrations of NaC2H3O2 in the culture medium and 0.75% concentration of NaCl. The results obtained enable to regard Acutodesmus dimorphus (Turpin P.M. Tsarenko IBASU-A 251 as an active carotenoids producer to be later applied in studies of hypersynthesis of individual classes of this pigment.

  14. A 1D Model of Radial Ion Motion Interrupted by Ion–Neutral Interactions in a Cometary Coma

    Vigren, E.; Eriksson, A. I.


    Because ion–neutral reaction cross sections are energy dependent, the distance from a cometary nucleus within which ions remain collisionally coupled to the neutrals is dictated not only by the comet’s activity level but also by the electromagnetic fields in the coma. Here we present a 1D model simulating the outward radial motion of water group ions with radial acceleration by an ambipolar electric field interrupted primarily by charge transfer processes with H2O. We also discuss the impact of plasma waves. For a given electric field profile, the model calculates key parameters, including the total ion density, n I , the H3O+/H2O+ number density and flux ratios, R dens and R flux, and the mean ion drift speed, , as a function of cometocentric distance. We focus primarily on a coma roughly resembling that of the ESA Rosetta mission target comet 67P/Churyumov–Gerasimenko near its perihelion in 2015 August. In the presence of a weak ambipolar electric field in the radial direction the model results suggest that the neutral coma is not sufficiently dense to keep the mean ion flow speed close to that of the neutrals by the spacecraft location (∼200 km from the nucleus). In addition, for electric field profiles giving n I and within limits constrained by measurements, the R dens values are significantly higher than values typically observed. However, when including the ion motion in large-amplitude plasma waves in the model, results more compatible with observations are obtained. We suggest that the variable and often low H3O+/H2O+ number density ratios observed may reflect nonradial ion trajectories strongly influenced by electromagnetic forces and/or plasma instabilities, with energization of the ion population by plasma waves.

  15. [H 3tren] 3+ templated iron fluorides; synthesis, crystal structures and Mössbauer studies

    Ali, Amor Ben; Grenèche, Jean-Marc; Leblanc, Marc; Maisonneuve, Vincent


    The hydrothermal synthesis, using tris-(2-ethylamino)amine ( tren) as a template, and the crystal structures of three new hybrid iron fluorides, (H 3O) 2·[H 3tren] 2·(FeF 6) 2·(FeF 5(H 2O))·2H 2O ( I), [H 3tren] 2·(FeF 6) 2·(FeF 2(H 2O) 4)·8H 2O ( II) and [H 3tren] 2·(FeF 6)·(F) 3·H 2O ( III), are reported. I, II, and III are triclinic ( P-1), monoclinic ( P2 1/ c) and orthorhombic ( I222), respectively. The structure of I is built up from isolated FeF 6 and FeF 5(H 2O) distorted octahedra separated by triprotonated [H 3tren] 3+ cations, disordered H 3O + cations and H 2O molecules. In II, Fe IIIF 6 and neutral [Fe IIF 2(H 2O) 4] octahedra form, together with [H 3tren] 3+ cations, infinite (100) layers separated by extra water molecules. The structure of III consists of isolated and disordered FeF 6 octahedra, fluoride anions F - connected to [H 3tren] 3+ cations and extra fluoride anions F - disordered with H 2O molecules. All [H 3tren] 3+ cations have a "spider" type conformation. 57Fe Mössbauer characterization shows that +III valence state can only be considered for iron cations in I and III and preliminary Mössbauer results are consistent with the presence of both +II and +III valences for iron cations in II, in agreement with the crystallographic results.

  16. Characterisation of the rare cadmium chromate pigment in a 19th century tube colour by Raman, FTIR, X-ray and EPR

    Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær


    In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO4·KOH·H2O or more accurately as KCd2(CrO4)2(H3O2) illustrating the μ-H3O2- species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V).

  17. Single-crystal X-ray diffraction study of synthetic sodium-hydronium jarosite

    Najorka, Jens; Lewis, James M. T.; Spratt, John; Sephton, Mark A.


    Na-H3O jarosite was synthesized hydrothermally at 413 K for 8 days and investigated using single-crystal X-ray diffraction (XRD) and electron microprobe analysis (EMPA). The chemical composition of the studied crystal is [Na0.57(3) (H3O)0.36 (H2O)0.07]A Fe2.93(3) (SO4)2 (OH)5.70 (H2O)0.30, and Fe deficiency was confirmed by both EMPA and XRD analysis. The single-crystal XRD data were collected at 298 and 102 K, and crystal structures were refined in space group Roverline{3}m. The room-temperature data match structural trends of the jarosite group, which vary linearly with the c axis. The low-temperature structure at 102 K shows an anisotropic decrease in the unit cell parameters, with c and a decreasing by 0.45 and 0.03 %, respectively. Structural changes are mainly confined to the A site environment. Only minor changes occur in FeO6 and SO4 polyhedra. The structure responds upon cooling by increasing bond length distortion and by decreasing quadratic elongation of the large AO12 polyhedra. The structural parameters at low temperature follow very similar patterns to structural changes that correspond to compositional variation in the jarosite group, which is characterised by the flexibility of AO12 polyhedra and rigidity of Fe(OH)4O2-SO4 layers. The most flexible areas in the jarosite structure are localized at AO12 edges that are not shared with neighbouring FeO6 octahedra. Importantly, for the application of XRD in planetary settings, the temperature-related changes in jarosite can mimic compositional change.

  18. Development of a PTR-TOFMS instrument for real-time measurements of volatile organic compounds in air

    Tanimoto, Hiroshi; Aoki, Nobuyuki; Inomata, Satoshi; Hirokawa, Jun; Sadanaga, Yasuhiro


    A proton transfer reaction-time-of-flight mass spectrometer (PTR-TOFMS) has been developed for real-time measurements of volatile organic compounds in air. The instrument is designed to be operated with a hollow cathode discharge ion source and an ion drift tube at relatively high pressures. Each component of the system, an ion source, a drift tube, an ion transfer region, and a time-of-flight mass spectrometer, are in detail characterized by a number of laboratory experiments. The optimized instrumental configuration enables us to gain high intensities of hydronium (H3O+) ions, typically ~7 × 105 counts for 1-min integration at a drift tube pressure of ~5 Torr. It also suppresses background signals, and interferences from sample air (NO+ and O2+), which undergo fast reactions with volatile organic compounds, to ~0.5% of those of H3O+ ions. We find that the use of the custom-built discharge source show higher overall sensitivities than of a commercially available radioactive source. Potentials to detect oxygenated VOCs (aldehydes, ketones, and alcohols), halocarbons, and amines are also suggested. The detection limits for acetaldehyde, acetone, isoprene, benzene, toluene, and p-xylene were determined to be at the sub-ppbv levels for a 1-min integration time. A good linear response at trace levels is certified, but slight sensitivity dependency on water vapor contents is revealedE We finally demonstrate that the instrument can be used for on-line monitoring to detect large variations from emission sources in real-time.

  19. The behavior of trace elements during schwertmannite precipitation and subsequent transformation into goethite and jarosite

    Acero, Patricia; Ayora, Carlos; Torrentó, Clara; Nieto, José-Miguel


    Schwertmannite is a ubiquitous mineral formed from acid rock drainage (ARD), and plays a major role in controlling the water chemistry of many acid streams. The formation of schwertmannite was investigated in the acid discharge of the Monte Romero abandoned mine (Iberian Pyrite Belt, SW, Spain). Schwertmannite precipitated from supersaturated solutions mainly owing to the oxidation of Fe(II) to Fe(III) and transformed with time into goethite and jarosite. In a few hours, schwertmannite precipitation removed more than half of the arsenic load from solution, whereas the concentration of divalent trace metals (Zn, Cu, Pb, Cd, Ni, and Co) remained almost unchanged. In the laboratory, natural schwertmannite was kept in contact with its coexisting acid water in a flask with a solid-liquid mass ratio of 1:5 for 353 days. During this time, the pH of the solution dropped from 3.07 to 1.74 and the concentrations of sulfate and Fe increased. During the first 164 days, schwertmannite transformed into goethite plus H 3O-jarosite but, subsequently, goethite was the only mineral to form. Some of the trace elements, such as Al, Cu, Pb, and As were depleted in solution during the first stage as schwertmannite transformed into goethite plus H 3O-jarosite. On the contrary, the transformation of schwertmannite to goethite (with no jarosite) during the second stage released Al, Cu, and As to the solution. Despite the variation in their concentrations in solution, approximately 80% of the total Al and Cu inventories and more than 99% As and Pb remained in the solid phase throughout the entire aging process.

  20. Water and Water Ions in the Martian Thermosphere/Ionosphere

    Fox, J. L.; Benna, M.; Mahaffy, P. R.; Jakosky, B. M.


    We present here the first model of the Martian thermosphere/ionosphere in which we predict the density profiles of water vapor and water ions in the altitude range 80 to 400 km. The model is based on data from the MAVEN spacecraft, including the NGIMS, LPW, EUVM and STATIC. The model includes 28 ions, of which 14 are protonated species, and 10 minor neutral species. The protonated species include H2O+ and H3O+, and the minor neutral species include H2O. These species are coupled to each other and to the background species by over 400 reactions. The peaks of the density profiles of water ions and OH+ are in fairly good agreement with the values measured by the NGIMS instrument. The density profiles of water vapor are computed with zero flux boundary conditions at the top and bottom of the model, which shows that water can be made in situ via ion chemistry, somewhat like in the interstelllar medium. It appears, however, that the predicted densities may be too small to account for the densities of H3O+ that are seen at low altitudes beyond the terminator. On the other hand, the densities of water vapor must be small enough so that HCO+ is not destroyed completely by proton transfer. The actual amount of water in the thermosphere is bracketed by these two requirements. The computed water vapor densities at the lower boundary are smaller than some of those at the upper boundaries of middle atmosphere models. We tentatively predict that there must be some influx of water from below. We also compute the Hn + species, where n=(1-3), and convincingly demonstrate the the mass-2 ion is H2+ and not D+, as it is on Venus.

  1. Synthesis and Crystal Structure of a Lanthanum(III) Complex with Chelidamic Acid

    ZOU Jian-Ping; ZHOU Guo-Wei; GUO Guo-Cong; YAN Liu-Shui; ZENG Gui-Sheng; HUANG Jin-Shun


    A new lanthanum complex, (H3O)2[La(C7H3NO5)2(H2O)2]2·3(H2O) or (H3O)2[La(HChel)2(H2O)2]2·3(H2O) 1 (H3Chel = 4-hydroxypyridine-2,6-dicarboxylic(chelidamic) acid), has been prepared by the hydrothermal reaction, and its crystal structure was determined based on single-crystal diffraction data. Compound 1 crystallizes in triclinic, space group P with a = 9.6939(19), b = 10.176(2), c = 11.502(2) (A), α = 111.52(3), β = 93.74(3), γ = 103.33(3)°, V = 1013.0(3) (A)3, Dc = 1.912 g/cm3, Z = 1, Mr = 1166.40, μ = 2.188 mm-1, λ(MoKα) = 0.71073 (A) and F(000) = 574. The final R = 0.0342 and wR = 0.0737 for 4080 observed reflections with I > 2σ(I), and R = 0.0429 and wR = 0.0772 for all data. Compound 1 contains two lanthanum ions, four chelidamic acid ligands, four coordinated water molecules, two hydroniums, and three discrete water molecules. The LaIII atom is ten-coordinated by four oxygen and two nitrogen atoms from two tridentate chelating chelidamic acid ligands, two carboxylic oxygen atoms from an adjacent chelidamic acid ligand and two coordinated water molecules, leading to a distorted dodecahedral geometry. A three-dimensional network is formed by H-bonds.


    杨恩翠; 郝金库; 王玉新; 曹映玉; 张颖


    The reaction conditions and reaction mechanism were studied on synthesis of isopropyl chloride from isopropanol and hydrochloric acid catalyzed by zinc chloride. The results showed that the yield of isopropyl chloride is 81.6% under the optimum reaction conditions. From the experimental results, we obtained the kinetic equation: r=k[ZnCl2]2.8[HCl][(CH3)2CHOH]. The apparent activation energy is 72.31 kJ/mol and the active component of the catalyst may be [(Zn2Cl5)-*(H3O)+]. The coexistence of SN1 and SN2 type reactions was proposed.%研究了以盐酸和异丙醇为原料,氯化锌为催化剂合成氯代异丙烷的工艺条件,并对反应动力学过程进行了分析。结果表明:反应在适宜工艺条件下,氯代异丙烷的收率为81.6%。本征动力学方程为r=k[ZnCl2]2.8[HCl][(CH3)2CHOH],表观反应活化能为72.31 kJ/mol,催化剂活性组分可能为[(Zn2Cl5)-*(H3O)+],反应以SN1和SN2并存历程进行。

  3. Tropical Greenhouse Measurements of Volatile Organic Compounds Using Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectromety (PTR-TOF-MS)

    Veres, P.; Auld, J.; Williams, J.


    In this presentation, we will summarize the results of measurements made in an approximately 1300 m3 tropical greenhouse at the Johannes Gutenberg University botanical garden in Mainz Germany conducted over a one month period. The greenhouse is home to a large variety of plant species from hot and humid regions of the world. The greenhouse is also host to several crops such as Cocoa and Cola Nut as well as ornamental plants. A particular focus of the species maintained are those which are considered ant plants, or plants which have an intimate relationship with ants in tropical habitats. Volatile organic compounds (VOCs) were measured using a Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) using H3O+, NO+, and O2+ ion chemistry. Measurements will be presented both for primary emissions observed in the closed greenhouse atmosphere as well as the oxidation products observed after the introduction of ambient ozone. The high resolving power (5000 m/Δm) of the time-of-flight instrument allows for the separation of isobaric species. In particular, both isoprene (68.1170 amu) and furan (68.0740 amu) were observed and separated as primary emissions during this study. The significance of this will be discussed in terms of both atmospheric implications as well as with respect to previous measurements of isoprene obtained using quadrupole PTR-MS where isobaric separation of these compounds is not possible. Additionally observed species (e.g. Methanol, Acetaldehyde, MVK and MEK) will be discussed in detail with respect to their behavior as a function of light, temperature and relative humidity. The overall instrument performance of the PTR-TOF-MS technique using the H3O+, NO+, and O2+ primary ions for the measurement of VOCs will be evaluated.

  4. Ethylene oxidation in a well-stirred reactor

    Marinov, N.M. [Lawrence Livermore National Lab., CA (United States); Malte, P.C. [Washington Univ., Seattle, WA (United States). Dept. of Mechanical Engineering


    The detailed ethylene oxidation data set of Thornton, obtained for a well-stirred reactor operated fuel-lean at atmospheric pressure and for temperatures of 1003K to 1253K, is used as a basis for the comparison of chemical kinetic mechanisms reported in the literature and for the development of a new ethylene oxidation mechanism. The mechanisms examined are those of Westbrook and Pitz and Dagaut et al. These mechanisms indicated that unusually large rates for the vinyl decomposition reaction are required to obtain agreement with the Thornton data set. A new ethylene oxidation mechanism is developed in order to overcome some of the drawbacks of the previous mechanisms. The new mechanism closely simulates the overall rate of loss of ethylene, and the concentation of CO, CO{sub 2}, H{sub 2}, CH{sub 2}O, C{sub 2}H{sub 2}, CH{sub 3}OH, CH{sub 4}, and C{sub 2}H{sub 6} measured for the stirred reactor. Predictions by this mechanism are dependent on a new high temperature vinyl oxidation route, C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O with a k{sub C2H3+O2=CH2CHO+O}/k{sub C2H3+O2=CH2O+HCO} branching ratio of 1.20 at 1053K to 2.05 at 1253K. The branching ratio values were dependent upon the extent of fall-off for the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}O + HCO reaction.

  5. Adsorption of enterobactin to metal oxides and the role of siderophores in bacterial adhesion to metals.

    Upritchard, Hamish G; Yang, Jing; Bremer, Philip J; Lamont, Iain L; McQuillan, A James


    The potential contribution of chemical bonds formed between bacterial cells and metal surfaces during biofilm initiation has received little attention. Previous work has suggested that bacterial siderophores may play a role in bacterial adhesion to metals. It has now been shown using in situ ATR-IR spectroscopy that enterobactin, a catecholate siderophore secreted by Escherichia coli, forms covalent bonds with particle films of titanium dioxide, boehmite (AlOOH), and chromium oxide-hydroxide which model the surfaces of metals of significance in medical and industrial settings. Adsorption of enterobactin to the metal oxides occurred through the 2,3-dihydroxybenzoyl moieties, with the trilactone macrocycle having little involvement. Vibrational modes of the 2,3-dihydroxybenzoyl moiety of enterobactin, adsorbed to TiO(2), were assigned by comparing the observed IR spectra with those calculated by the density functional method. Comparison of the observed adsorbate IR spectrum with the calculated spectra of catecholate-type [H(2)NCOC(6)H(3)O(2)Ti(OH)(4)](2-) and salicylate-type [H(2)NCOC(6)H(3)O(2)HTi(OH)(4)](2-) surface complexes indicated that the catecholate type is dominant. Analysis of the spectra for enterobactin in solution and that adsorbed to TiO(2) revealed that the amide of the 2,3-dihydroxybenzoylserine group reorientates during coordination to surface Ti(IV) ions. Investigation into the pH dependence of enterobactin adsorption to TiO(2) surfaces showed that all 2,3-dihydroxybenzoyl groups are involved. Infrared absorption bands attributed to adsorbed enterobactin were also strongly evident for E. coli cells attached to TiO(2) particle films. These studies give evidence of enterobactin-metal bond formation and further suggest the generality of siderophore involvement in bacterial biofilm initiation on metal surfaces.

  6. Submillimetric study of nearby galaxies: A tool for new extragalactic molecules

    Villicana Pedraza, Ilhuiyolitzin; Guesten, Rolf; Armijos Abendaño, Jairo; Carreto, Francisco; Martin, Sergio; Martin-Pintado, Jesus; Requena-Torres, Miguel; Perez-Beaupuits, Juan Pablo


    We present the first submillimetre line survey of extragalactic sources carried out by APEX, the results were presented inside of Villicana-Pedraza phd thesis in 2015. The surveys cover the 0.8 mm atmospheric window toward NGC253, NGC4945 and Arp220. We found HCN, C2H, CN, CS, C34S, HCO+, HNC, CO, N2H+, CH3OH are presents in all the sources, while 13CO,C18O and C17O, HNCO, H2CO, H2CS, SO, NO, SO2 were detected toward NGC253 and NGC4945, 13CN, *CO+, OCS, H2S in Arp220, 13CS, NH2CN, SiO in NGC253, and c-C3H2 in NGC4945 were detected. Column densities and rotation temperatures have been determinate using the Local Thermodinamical Equilibrium(LTE) line profile simulation and fitting in the MADCUBA IJ software. The differences found in the 32S/34S and 18O/17O ratios between the GC and the starburst galaxies NGC 4945 and NGC 253 suggest that the gas is less processed in the latter than in the GC. The high 18O/17O ratios in the galaxies NGC 4945 and NGC 253 suggest also material less processed in the nuclei of these galaxies than in the GC. This is consistent with the claim that 17O is a more representative primary product than 18O in stellar nucleosynthesis (Wilson and Rood 1994); Also, we did a Multitransitions study of H3O+ at 307GHz, 364GHz, 388GHz and 396GHz. From our non-LTE analysis of H3O+ in NGC253 with RADEX we found that the collisional excitation cannot explain the observed intensity of the ortho 396 GHz line. Excitation by radiation from the dust in the Far-IR can roughly explain the observations if the H2 densities are relatively low. From the derived H3O+ column densities we conclude that the chemistry of this molecule is dominated by ionization produce by the starburst in NGC253 (UV radiation from the O stars) and Arp 220 (cosmic rays from the supernovae) and likely from the AGN in NGC4549 (X-rays ); We report, for the first time, the tentative detection of the molecular ion HCNH+ (precursor of HCN and HNC) toward a galaxy, NGC4945, the abundance is much

  7. Effect of SiO2 on relaxation phenomena and mechanism of ion conductivity of [Nafion/(SiO2)x] composite membranes.

    Di Noto, Vito; Gliubizzi, Rocco; Negro, Enrico; Pace, Giuseppe


    water [(H2O)n]; (b) water solvating the oxonium ions directly interacting with sulfonic acid groups [H3O+...SO3(-)-].(H2O)n; (c) water aggregates associated with H3O+ ions [H3O+.(H2O)n]; and (d) low associated water species in dimer form [(H2O)2]. The conductivity mechanism and relaxation events were investigated by broadband dielectric spectroscopy (BDS). [Nafion/(SiO2)x] nanocomposite membranes were found to possess two different molecular relaxation phenomena which are associated with the alpha-relaxation mode of PTFE-like fluorocarbon domains and the beta-relaxation mode of acid side groups of the Nafion component. Owing to their strong coupling, both these relaxation modes are diagnostic for the interactions between the polar groups of the Nafion host polymer and the (SiO2)x oxoclusters and play a determining role in the conductivity mechanism of the membranes. The studies support the proposal that long-range proton charge transfer in [Nafion/(SiO2)x] composites takes place due to a mechanism involving exchange of the proton between the four water domains. This latter proton transfer occurs owing to a subsequent combination of domain intersections resulting from the water domain fluctuations induced by the molecular relaxation events of host Nafion polymer.

  8. A computational mechanistic investigation of hydrogen production in water using the [Rh(III)(dmbpy)2Cl2](+)/[Ru(II)(bpy)3](2+)/ascorbic acid photocatalytic system.

    Kayanuma, Megumi; Stoll, Thibaut; Daniel, Chantal; Odobel, Fabrice; Fortage, Jérôme; Deronzier, Alain; Collomb, Marie-Noëlle


    We recently reported an efficient molecular homogeneous photocatalytic system for hydrogen (H2) production in water combining [Rh(III)(dmbpy)2Cl2](+) (dmbpy = 4,4'-dimethyl-2,2'-bipyridine) as a H2 evolving catalyst, [Ru(II)(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and ascorbic acid as a sacrificial electron donor (Chem. - Eur. J., 2013, 19, 781). Herein, the possible rhodium intermediates and mechanistic pathways for H2 production with this system were investigated at DFT/B3LYP level of theory and the most probable reaction pathways were proposed. The calculations confirmed that the initial step of the mechanism is a reductive quenching of the excited state of the Ru photosensitizer by ascorbate, affording the reduced [Ru(II)(bpy)2(bpy˙(-))](+) form, which is capable, in turn, of reducing the Rh(III) catalyst to the distorted square planar [Rh(I)(dmbpy)2](+) species. This two-electron reduction by [Ru(II)(bpy)2(bpy˙(-))](+) is sequential and occurs according to an ECEC mechanism which involves the release of one chloride after each one-electron reduction step of the Rh catalyst. The mechanism of disproportionation of the intermediate Rh(II) species, much less thermodynamically favoured, cannot be barely ruled out since it could also be favoured from a kinetic point of view. The Rh(I) catalyst reacts with H3O(+) to generate the hexa-coordinated hydride [Rh(III)(H)(dmbpy)2(X)](n+) (X = Cl(-) or H2O), as the key intermediate for H2 release. The DFT study also revealed that the real source of protons for the hydride formation as well as the subsequent step of H2 evolution is H3O(+) rather than ascorbic acid, even if the latter does govern the pH of the aqueous solution. Besides, the calculations have shown that H2 is preferentially released through an heterolytic mechanism by reaction of the Rh(III)(H) hydride and H3O(+); the homolytic pathway, involving the reaction of two Rh(III)(H) hydrides, being clearly less favoured. In parallel to this

  9. Development of a reaxff reactive force field for silicon/oxygen/hydrogen/fluoride interactions and applications to hydroxylation and friction

    Yeon, Jejoon

    higher strain energy. In addition, we found three distinct hydroxylation paths -- H3O+ formation reaction from the adsorbed water, proton donation from H3O+, and the direct dissociation of the adsorbed water molecule. Because water molecules and their hydrogen bond network behave differently with respect to temperature ranges, silanol formation is also affected by temperature. The formation of surface hydroxyl in an amorphous silica double slit displays a similar tendency: SiOH formation prefers high-strain sites. Silanol formation related with H3O + formation and dissociation is observed in hydroxylation of amorphous SiO2, similar with the results from silica nano wire simulation. These results are particularly relevant to the tribological characteristics of surfaces, enabling the prediction of the attachment site of the lubrication film on silica surfaces with a locally strained geometry.

  10. Interruption of ion acceleration by collisions with neutrals in a cometary coma: a 1D model applied to 67P/Churyumov-Gerasimenko

    Vigren, Erik; Eriksson, Anders I.; Johansson, Fredrik L.


    We present a 1D model of a cometary ionosphere with the main purpose to investigate the ability of the neutrals to hamper ion acceleration along electric fields in the radial direction. Because ion-neutral reaction cross-sections are energy dependent, the distance from a cometary nucleus within which ions remain collisionally coupled to the neutrals is dictated not only by the comet's activity level but also by the electromagnetic fields in the coma. As electron cooling is inefficient due to low neutral gas density and density decays with cometocentric distance a significant ambipolar electric field may develop. In the model we treat charge transfer processes as replacing a fast ion and a slow neutral with a fast neutral and a slow ion. For a given neutral background and electric field profile, the model, which in essence is based on the multiplication principle of probabilities, calculates observables such as the total ion number density, the H3O+/H2O+ number density ratio, the mean ion drift speed and the ion energy distribution function, as a function of cometocentric distance. The model is applied to different conditions encountered by Rosetta during its mission to comet 67P/Churyumov-Gerasimenko. Our findings include i) that the activity, even near perihelion, was probably not high enough for an efficient ion-neutral coupling all the way to the spacecraft location, and ii) that model runs using electric field profiles that give ion number densities and mean flow speeds within limits constrained by RPC observations tend to give H3O+/H2O+ number density ratios higher than typically observed by ROSINA/DFMS (e.g., [1]). We discuss also the influence on the results of including the ion motion in large-amplitude plasma waves into the model. Finally we highlight some reactions for which determinations of cross-sections at low collision energies would be valuable. [1] Fuselier, S.A., et al. 2016, MNRAS, 462, S312

  11. Particulate matter (PM) episodes at a suburban site in Hong Kong: evolution of PM characteristics and role of photochemistry in secondary aerosol formation

    Qin, Yi Ming; Jie Li, Yong; Wang, Hao; Lee, Berto Paul Yok Long; Huang, Dan Dan; Keung Chan, Chak


    course of 6 h. The "less-oxidized" SOA (SVOOA) was initially formed at a higher rate than the "more-oxidized" SOA (LVOOA). The SVOOA transformed to LVOOA at the later stage of photochemical aging. This transformation was further supported by mass spectral analysis, which showed an increase in the most oxidized ion (CO2+) and decreases in moderately oxidized ones (C2H3O+, C3H3O+ and C3H5O+). By measuring the physical and chemical properties of PM in a highly time-resolved manner, the current study was able to demonstrate the dynamic and complex nature of PM transformation during high-PM episodes.

  12. Solubility properties of synthetic and natural meta-torbernite

    Cretaz, Fanny; Szenknect, Stéphanie; Clavier, Nicolas; Vitorge, Pierre; Mesbah, Adel; Descostes, Michael; Poinssot, Christophe; Dacheux, Nicolas


    Meta-torbernite, Cu(UO2)2(PO4)2ṡ8H2O, is one of the most common secondary minerals resulting from the alteration of pitchblende. The determination of the thermodynamic data associated to this phase appears to be a crucial step toward the understanding the origin of uranium deposits or to forecast the fate and transport of uranium in natural media. A parallel approach based on the study of both synthetic and natural samples of meta-torbernite (H3O)0.4Cu0.8(UO2)2(PO4)2ṡ7.6H2O was set up to evaluate its solubility constant. The two solids were first thoroughly characterized and compared by means of XRD, SEM, X-EDS analyses, Raman spectroscopy and BET measurements. The solubility constant was then determined in both under- and supersaturated conditions: the obtained value appeared close to logKs,0°(298 K) = -52.9 ± 0.1 whatever the type of experiment and the sample considered. The joint determination of Gibbs free energy (ΔRG°(298 K) = 300 ± 2 kJ mol-1) then allowed the calculation of ΔRH°(298 K) = 40 ± 3 kJ mol-1 and ΔRS°(298 K) = -879 ± 7 J mol-1 K-1. From these values, the thermodynamic data associated with the formation of meta-torbernite (H3O)0.4Cu0.8(UO2)2(PO4)2ṡ7.6H2O were also evaluated and found to be consistent with those previously obtained by calorimetry, showing the reliability of the method developed in this work. Finally, the obtained data were implemented in a calculation code to determine the conditions of meta-torbernite formation in environmental conditions typical of a former mining site. SI=log({Q}/{Ks}) with Q=∏i( where νi is the stoichiometric coefficient (algebraic value) of species i and ai the nonequilibrium activity of i.

  13. Surface desorption atmospheric pressure chemical ionization mass spectrometry for rapid analysis of volatile components of Ginseng Flos%表面解吸常压化学电离质谱快速分析人参花中挥发性成分

    王恩鹏; 越皓; 陈焕文; 刘淑莹


    Objective:To establish a method of surface desorption atmospheric pressure chemical ionization (SDAPCI)-mass spectrometry(MS) for identification of the volatile components of Ginseng Flos.Methods:Through the SDAPCI approach,the direct detection was carried out for the volatile oil which was gained by a steam distillation method without any chromatographic separation.An in-house corona discharge was employed to generate the primary ions such as H3O + which was combined with the volatile compounds to generate [M + H] + for mass analysis in the positive ion detection mode in the ambient air with 50% relative humidity.Results:Through this method,34 compounds were detected,of which 10 were identified as the volatile oil from Ginseng Flos.Conclusion:Compared with the results of gas chromatography (GC)-mass spectrometry (MS),SDAPCI-MS is more rapid,sensitive and sample-preparation-free for analysis of volatile components of the plants,which can be used for real time and online detection of various compounds in complex matrices including volatile samples.%目的:建立新型表面解吸常压化学电离(surface desorption atmospheric pressure chemical ionization,SDAPCI)质谱法对人参花蕾中挥发性成分的快速鉴别.方法:采用SDAPCI质谱法,无需色谱分离,对水蒸气蒸馏法获得的人参花挥发油进行直接检测.在空气相对湿度为50%的敞开体系下,通过电晕放电,在正离子模式可产生以H3O+为主的初级离子,使得挥发成分与之结合产生[M+H]+而被检测.结果:通过该方法共检测出34个化合物,通过串联质谱(MS/MS)分析结合气相色谱-质谱(GC-MS)数据比对,鉴定出其中10个挥发性成分.结论:实验结果表明,与GC-MS相比,该方法快捷灵敏,无污染,不需要样本制备,可广泛应用于实时及在线检测复杂基质中挥发性成分的鉴定.

  14. Improvement of glassy sol-gel sensors for preventive conservation of historical materials against acidity

    Carmona, N.


    Full Text Available Sensors based on sol-gel glassy coatings doped with 2[4-(dimethyl-amino phenylazo] benzoic acid are able to change their optical absorption when they are submitted to different concentration of H3O+ and OH-. The sensors behaviour in field tests was studied in Cracow (Poland, varying the normal procedure of operation to improve their response. Both the sensors optical parameters and the environmental conditions (temperature, humidity, pressure, SO2 and NOx concentrations were measured. The sensors response was analysed in terms of their visible absorbance changes, which are due to local neutralisation reactions in the sensors surface by the join effect of acid pollutants and humidity. Correlations between the main acid pollutant (SO2 concentration and the sensors response are established to provide a relation between the optical absorption and the environmental pH. The sensors are able to detect and monitorise environmental acidity, as well as to alert on the pollutant concentration that may damage most of the historical materials.

    Los sensores a base de recubrimientos vítreos sol-gel dopados con ácido 2[4-(dimetil-amino fenilazo] benzoico son capaces de cambiar su absorción óptica cuando se someten a distintas concentraciones de iones H3O+ y OH-. La respuesta de los sensores en ensayos de campo se estudió en Cracovia (Polonia variando el procedimiento normal de uso, con el fin de mejorar su respuesta. Se midieron tanto los parámetros ópticos de los sensores como las condiciones ambientales (temperatura, humedad, presión y concentraciones de SO2 y de NOx. La respuesta de los sensores se analizó en términos de los cambios de su absorción visible. Dichos cambios se deben a reacciones locales de neutralización que tienen lugar en la superficie de los sensores, debido al efecto conjunto de los contaminantes de carácter ácido y a la humedad ambiental. Se establecieron correlaciones entre la concentración del contaminante

  15. Pectin methylesterase activity determined by different methods and thermal inactivation of exogenous pme in mango juice Determinação da atividade da pectina metilesterase por diferentes métodos e inativação térmica da PME exógena no suco de manga

    Samantha Lemke Gonzalez


    Full Text Available Pectin methylesterase (PME hydrolyzes methyl ester groups in pectin chains to form carboxylic groups, releasing methanol and H3O+. The aim of this study was to determine PME activity in samples of pectinases by UV-VIS spectroscopy, to measure the acid and methanol produced in the reaction of pectin with pectinase and to verify the thermal inactivation of exogenous PME in mango juice. The activity of PME in samples of pectinase was determined by potentiometry, UV-VIS spectroscopy, and by the action of alcohol oxidase. The reaction showed greater activity at pH 4.0 to 4.5 and at a temperature of 45° C. PME activity determined by UV-VIS spectroscopy with bromophenol blue indicator showed a good correlation with the activity determined by potentiometry and with alcohol oxidase. The results showed that bromophenol blue indicators can be used to determine PME activity in samples of pectinases where the optimum pH is located in the acidic range. The thermal inactivation of exogenous PME in mango juice occurred at 75° C for 20 min of exposure.A PME hidrolisa os grupos metil éster na cadeia da pectina, formando grupos carboxílicos, liberando metanol e H3O+. Objetivou-se, com o presente estudo, determinar a atividade da PME em amostras de pectinases por espectroscopia Uv-vis para quantificar o ácido e o metanol produzido na reação da pectina com as pectinases e verificar a inativação térmica da PME exógena no suco de manga. A atividade da PME nas três amostras de pectinases foi determinada por potenciometria, espectroscopia Uv-Vis, e pela ação da álcool oxidase. A reação mostrou uma maior atividade em H de 4,0 a 4,5 e a temperatura de 45º C. A atividade da PME, determinada por UV-Vis com o indicador azul de bromofenol apresentou uma boa correlação com a atividade determinada por potenciometria e com a álcool oxidase. Os resultados mostraram que o indicador azul de bromofenol pode ser utilizado para determinar a atividade da PME em

  16. 一种新颖的稀土-2-羟基烟酸的配合物的结构和光谱性质研究%Structural and Spectral Study of a Novel Lanthanide 2-hydroxynicotinic Acid Coordination Polymer

    梅洪鑫; 李光满; 邓松; 孙燕琼; 陈义平; 张汉辉


    A novel lanthanide 2-hydroxynicotinic acid coordination polymer 1 {[LaL(HL)(H2O)3]l/3(SO4 )2/3(H3O)2H2O} (H2L=2-hydroxynicotinic acid) has been synthesized under hydrothermal condition and characterized by crystal X-ray diffraction, IR, UV, TGA, two-dimensional infrared (2D IR) correlation spectroscopy with magnetic and thermal perturbation. In 1, La ions are connected by 2-hydroxynicotinic acid through both carboxylate oxygen atoms and oxygen atoms from hydroxyl group in pyridine to generate a 2D layer in the ab plane, these layers are further connected by weak interactions to form a 3D framework along c axis. The response of out-of-plane bending vibrations of N-H and C-H are remarkable in the 2D IR correlation spectra under magnetic perturbation, this may attributes to the inducement of ;relectron cloud deformation under magnetic perturbation, ν4 vibrations from SO_4~2- was also sensitive to magnetic perturbation. In addition, stretching vibrations from N-H are sensitive to thermal perturbation.%通过水热反应合成了一种新颖的稀土2-羟基烟酸的配合物{[ LaL (HL)( H2O)3] 1/3 (SO4) 2/3(H3O)2H2O}(H2L=2-hydroxynicotinic acid).X-ray单晶衍射分析可知,2-羟基烟酸通过羧基O和羟基O原子桥连La离子,形成二维层状结构,层与层之间通过弱作用力拓展为三维结构.二维相关光谱分析表明N-H面外弯曲振动和C-H面外弯曲振动对磁微扰比较敏感,这可能是吡啶环上π电子云在磁微扰下变形引起C-H和N-H面外弯曲振动的响应,SO2-4的v4振动和羧基不对称伸缩振动对磁微扰也比较敏感;热微扰下N-H伸缩振动比较敏感.此外还对化合物进行了紫外和热重分析.

  17. Thermodynamic properties and crystal structure refinement of ferricopiapite, coquimbite, rhomboclase, and Fe2(SO4)3(H2O)5

    Majzlan, J.; Navrotsky, A.; McCleskey, R.B.; Alpers, C.N.


    Enthalpies of formation of ferricopiapite [nominally Fe4.67(SO4)6(OH)2 (H2O)20]. coquimbite [Fe2(SO4)3(H2O)9], rhomboclase [(H3O)Fe(SO4)2 (H2O)3], and Fe2(SO4)3(H2O)5 were measured by acid (5 N HCl) solution calorimetry. The samples were characterized by wet chemical analyses and synchrotron powder X-ray diffraction (XRD). The refinement of XRD patterns gave lattice parameters, atomic positions, thermal factors, and occupancies of the sites. The calculated formulae differ slightly from the nominal compositions: Fe4.78(SO4)6 (OH)2.34(H2O)20.71 (ferricopiapite), (Fe1.47Al0.53)(SO4)3 (H2O)9.65 (coquimbite), (H3O)1.34Fe(SO4)2.17 (H2O)3.06 (rhomboclase), and Fe2(SO4)3 (H2O)5.03. All thermodynamic data are given per mole of these formulae. The measured standard enthalpies (in kJ/mol) of formation from the elements (crystalline Fe, Al, S, and ideal gases O2 and H2) at T = 298.15 K are -4115.8??4.1 [Fe2(SO4)3 (H2O)5.03], -12045.1??9.2 (ferricopiapite), -5738.4??3.3 (coquimbite), and -3201.1??2.6 (rhomboclase). Standard entropy (S??) was estimated as a sum of entropies of oxide, hydroxide, and sulfate components. The estimated S?? (in J/mol.K) values for the iron sulfates are 488.2 [Fe2(SO4)3 (H2O)5.03], 1449.2 (ferricopiapite), 638.3 (coquimbite), and 380.1 (rhomboclase). The calculated Gibbs free energies of formation (in kJ/mol) are -3499.7??4.2 [Fe2(SO4)3 (H2O)5.03], -10089.8??9.3 (ferricopiapite), -4845.6??3.3 (coquimbite), and -2688.0??2.7 (rhomboclase). These results combined with other available thermodynamic data allow construction of mineral stability diagrams in the FeIII2(SO4)3-FeII SO4-H2O system. One such diagram is provided, indicating that the order of stability of ferric sulfate minerals with decreasing pH in the range of 1.5 to -0.5 is: hydronium jarosite, ferricopiapite, and rhomboclase. ?? 2006 E. Schweizerbart'sche Verlagsbuchhandlung.

  18. Evaluación de procedimientos de extracción de cinc presente en una zeolita activada

    Mercedes Machúa Veitía


    Full Text Available Los productos activos zeolíticos (PAZ están enriquecidos con un catión que en nuestro caso determina su acción antimicrobiana. Se establecieron las condiciones para la extracción de este elemento, considerando las características intrínsecas de esta materia prima y sus formas terminadas tabletas y cremas. Se realizan diferentes tratamientos a las muestras optimizando las condiciones de trabajo. La determinación del contenido de cinc se realiza por fluorescencia de rayos X y espectrofotometría de absorción atómica. Se estableció el ataque triácido con H2SO4 HNO3 (2:3 y HCl como óptimo para el tratamiento de cremas y tabletas, mientras que el principio activo (PAZ se trató con intercambio iónico.Active zeolite products (AZP are enriched with a cathion that determines their animicrobial effects. The extraction conditions were set taking inherent features of the raw material and its forms - tablets and creams - into account. Different treatment were applied to samples under optimized working conditions. Zinc conten was estimated by X - ray fluorescence and atomic absorption spectrophotometry. There - acid effect treatment with H2DO4 HNO (2:3 and HCL as an optimal method for treatting tablets and creams was shown whereas the active principla (AZ was treated with ion - exchange.

  19. Acidity enhancement of unsaturated bases of group 15 by association with borane and beryllium dihydride. Unexpected boron and beryllium Brønsted acids.

    Martín-Sómer, Ana; Mó, Otilia; Yáñez, Manuel; Guillemin, Jean-Claude


    The intrinsic acidity of CH2[double bond, length as m-dash]CHXH2, HC[triple bond, length as m-dash]CXH2 (X = N, P, As, Sb) derivatives and of their complexes with BeH2 and BH3 has been investigated by means of high-level density functional theory and molecular orbital ab initio calculations, using as a reference the ethyl saturated analogues. The acidity of the free systems steadily increases down the group for the three series of derivatives, ethyl, vinyl and ethynyl. The association with both beryllium dihydride and borane leads to a very significant acidity enhancement, being larger for BeH2 than for BH3 complexes. This acidity enhancement, for the unsaturated compounds, is accompanied by a change in the acidity trends down the group, which do not steadily decrease but present a minimum value for both the vinyl- and the ethynyl-phosphine. When the molecule acting as the Lewis acid is beryllium dihydride, the π-type complexes in which the BeH2 molecules interact with the double or triple bond are found, in some cases, to be more stable, in terms of free energies, than the conventional complexes in which the attachment takes place at the heteroatom, X. The most important finding, however, is that P, As, and Sb ethynyl complexes with BeH2 do not behave as P, As, or Sb Brønsted acids, but unexpectedly as Be acids.

  20. Moderate Temperature Dense Phase Hydrogen Storage Materials within the US Department of Energy (DOE H2 Storage Program: Trends toward Future Development

    Scott McWhorter


    Full Text Available Hydrogen has many positive attributes that make it a viable choice to augment the current portfolio of combustion-based fuels, especially when considering reducing pollution and greenhouse gas (GHG emissions. However, conventional methods of storing H2 via high-pressure or liquid H2 do not provide long-term economic solutions for many applications, especially emerging applications such as man-portable or stationary power. Hydrogen storage in materials has the potential to meet the performance and cost demands, however, further developments are needed to address the thermodynamics and kinetics of H2 uptake and release. Therefore, the US Department of Energy (DOE initiated three Centers of Excellence focused on developing H2 storage materials that could meet the stringent performance requirements for on-board vehicular applications. In this review, we have summarized the developments that occurred as a result of the efforts of the Metal Hydride and Chemical Hydrogen Storage Centers of Excellence on materials that bind hydrogen through ionic and covalent linkages and thus could provide moderate temperature, dense phase H2 storage options for a wide range of emerging Proton Exchange Membrane Fuel Cell (PEM FC applications.

  1. Selectivity Mechanism of the Voltage-gated Proton Channel, HV1

    Dudev, Todor; Musset, Boris; Morgan, Deri; Cherny, Vladimir V.; Smith, Susan M. E.; Mazmanian, Karine; Decoursey, Thomas E.; Lim, Carmay


    Voltage-gated proton channels, HV1, trigger bioluminescence in dinoflagellates, enable calcification in coccolithophores, and play multifarious roles in human health. Because the proton concentration is minuscule, exquisite selectivity for protons over other ions is critical to HV1 function. The selectivity of the open HV1 channel requires an aspartate near an arginine in the selectivity filter (SF), a narrow region that dictates proton selectivity, but the mechanism of proton selectivity is unknown. Here we use a reduced quantum model to elucidate how the Asp-Arg SF selects protons but excludes other ions. Attached to a ring scaffold, the Asp and Arg side chains formed bidentate hydrogen bonds that occlude the pore. Introducing H3O+ protonated the SF, breaking the Asp-Arg linkage and opening the conduction pathway, whereas Na+ or Cl- was trapped by the SF residue of opposite charge, leaving the linkage intact, thus preventing permeation. An Asp-Lys SF behaved like the Asp-Arg one and was experimentally verified to be proton-selective, as predicted. Hence, interacting acidic and basic residues form favorable AspH0-H2O0-Arg+ interactions with hydronium but unfavorable Asp--X-/X+-Arg+ interactions with anions/cations. This proposed mechanism may apply to other proton-selective molecules engaged in bioenergetics, homeostasis, and signaling.

  2. Mass spectrometric and quantum chemical determination of proton water clustering equilibria

    Likholyot, Alexander; Lemke, Kono H.; Hovey, Jamey K.; Seward, Terry M.


    We report on the thermochemistry of proton hydration by water in the gas phase both experimentally using high-pressure mass spectrometry (HPMS) and theoretically using multilevel G3, G3B3, CBS-Q, CBS-QB3, CBS/QCI-APNO as well as density functional theory (DFT) calculations. Gas phase hydration enthalpies and entropies for protonated water cluster equilibria with up to 7 waters (i.e., n ⩽ 7H 3O +·(H 2O) n) were observed and exhibited non-monotonic behavior for successive hydration steps as well as enthalpy and entropy anomalies at higher cluster rank numbers. In particular, there is a significant jump in the stepwise enthalpies and entropies of cluster formation for n varying from 6 to 8. This behavior can be successfully interpreted using cluster geometries obtained from quantum chemical calculations by considering the number of additional hydrogen bonds formed at each hydration step and simultaneous weakening of ion-solvent interaction with increasing cluster size. The measured total hydration energy for the attachment of the first six water molecules around the hydronium ion was found to account for more than 60% of total bulk hydration free energy.

  3. Solution processed aluminum paper for flexible electronics.

    Lee, Hye Moon; Lee, Ha Beom; Jung, Dae Soo; Yun, Jung-Yeul; Ko, Seung Hwan; Park, Seung Bin


    As an alternative to vacuum deposition, preparation of highly conductive papers with aluminum (Al) features is successfully achieved by the solution process consisting of Al precursor ink (AlH(3){O(C(4)H(9))(2)}) and low temperature stamping process performed at 110 °C without any serious hydroxylation and oxidation problems. Al features formed on several kinds of paper substrates (calendar, magazine, and inkjet printing paper substrates) are less than ~60 nm thick, and their electrical conductivities were found to be as good as thermally evaporated Al film or even better (≤2 Ω/□). Strong adhesion of Al features to paper substrates and their excellent flexibility are also experimentally confirmed by TEM observation and mechanical tests, such as tape and bending tests. The solution processed Al features on paper substrates show different electrical and mechanical performance depending on the paper type, and inkjet printing paper is found to be the best substrate with high and stable electrical and mechanical properties. The Al conductive papers produced by the solution process may be applicable in disposal paper electronics.

  4. Trapped Hydronium Radical Produced by Ultraviolet Excitation of Substituted Aromatic Molecule.

    Hernández, Federico J; Capello, Marcela C; Naito, Ayumi; Manita, Shun; Tsukada, Kohei; Miyazaki, Mitsuhiko; Fujii, Masaaki; Broquier, Michel; Gregoire, Gilles; Dedonder-Lardeux, Claude; Jouvet, Christophe; Pino, Gustavo A


    The gas phase structure and excited state dynamics of o-aminophenol-H2O complex have been investigated using REMPI, IR-UV hole-burning spectroscopy, and pump-probe experiments with picoseconds laser pulses. The IR-UV spectroscopy indicates that the isomer responsible for the excitation spectrum corresponds to an orientation of the OH bond away from the NH2 group. The water molecule acts as H-bond acceptor of the OH group of the chromophore. The complexation of o-aminophenol with one water molecule induced an enhancement in the excited state lifetime on the band origin. The variation of the excited state lifetime of the complex with the excess energy from 1.4 ± 0.1 ns for the 0-0 band to 0.24 ± 0.3 ns for the band at 0-0 + 120 cm(-1) is very similar to the variation observed in the phenol-NH3 system. This experimental result suggests that the excited state hydrogen transfer reaction is the dominant channel for the non radiative pathway. Indeed, excited state ab initio calculations demonstrate that H transfer leading to the formation of the H3O(•) radical within the complex is the main reactive pathway.

  5. Ortho-to-para abundance ratios of NH2 in 26 comets: implications for the real meaning of OPRs

    Shinnaka, Yoshiharu; Kawakita, Hideyo; Jehin, Emmanuël; Decock, Alice; Hutsemékers, Damien; Manfroid, Jean


    Abundance ratios of nuclear-spin isomers for cometary molecules having identical protons, such as water and ammonia, have been measured and discussed from the viewpoint that they are primordial characters in comet. In the case of ammonia, its ortho-to-para abundance ratio (OPR) is usually estimated from OPRs of NH2 because of difficulty in measuring OPR of ammonia directly. We report our survey for OPRs of NH2 in 26 comets. A weighted mean of ammonia OPRs for the comets is 1.12 ± 0.01 and no significant difference is found between the Oort Cloud comets and the Jupiter-family comets. These values correspond to ˜30 K as nuclear-spin temperatures. The OPRs of ammonia in comets probably reflect the physicochemical conditions in coma, rather than the conditions for the molecular formation or condensation in the pre-solar molecular cloud/the solar nebula, based on comparison of OPRs (and nuclear-spin temperatures) of ammonia with those of water, 14N/15N ratios in ammonia, and D/H ratios in water. The OPRs could be reset to a nuclear-spin weights ratio in solid phase and modified by interactions with protonated ions like H3O+, water clusters (H2O)n, ice grains, and paramagnetic impurities (such as O2 molecules and grains) in the inner coma gas. Relationship between the OPRs of ammonia and water is a clue to understanding the real meaning of the OPRs.

  6. A novel Ni/Na - Containing inorganic-organic hybrid supramolecule based on polyoxometalate and EDTA with ultraviolet-visible light photochromism

    Xiao, Han-Xi; Teng, Chun-Lin; Cai, Qing; Sun, Su-Qin; Cai, Tie-Jun; Deng, Qian


    A novel Ni/Na - containing inorganic-organic hybrid supramolecule {(PW12O40)·[Na2(NiH2EDTA·H2O)(H4EDTA)·2H2O]·2H2O·H3O}n (short for NiEDTA-PW12) has been successfully synthesized by solution method, and investigated by thermogravimetric-differential thermal analysis (TG-DTA), ultraviolet visible (UV-Vis) spectroscopy, cyclic voltammetry (CV), photoluminescence (PL), ultraviolet visible diffuse reflectance spectrum (UV-vis DRS) and single-crystal X-ray diffraction (XRD). NiEDTA-PW12 exhibits intriguing infinite supramolecular structure with Na+ ions as linker. Furthermore, NiEDTA-PW12 displays a fast-responsive reversible photochromism under ultraviolet or visible light. The photochromic property of NiEDTA-PW12 has been investigated by techniques of UV-vis DRS and PL, and the impact of the O2 on fading of the colored NiEDTA-PW12 has been investigated.

  7. Synthesis, crystal structure, and proton conductivity of one-dimensional, two-dimensional, and three-dimensional zirconium phosphonates based on glyphosate and glyphosine.

    Taddei, Marco; Donnadio, Anna; Costantino, Ferdinando; Vivani, Riccardo; Casciola, Mario


    The reaction of two small phosphono-amino acids based on glycine (glyphosine and glyphosate) with zirconium under mild conditions led to the attainment of three related zirconium derivatives with 1D, 2D, and 3D structures of formulas ZrF[H3(O3PCH2NHCH2COO)2] (1), Zr3H8[(O3PCH2)2NCH2COO]4·2H2O (2), and Zr[(O3PCH2)(HO3PCH2)NHCH2COOH]2·2H2O (3), respectively, whose structures were solved by X-ray powder and single-crystal diffraction data. The glyphosate derivative has 1D ribbon-type structure whereas the dimensionality of the glyphosine-derived materials (2D and 3D) can be tuned by changing the synthesis conditions. The low-dimensional compounds (1 and 2) can be directly produced in the form of nanoparticles with different size and morphology whereas the 3D compound (3) has a higher crystallinity and can be obtained as single crystals with a prismatic shape. The different structural dimensionality reflects the shape and size of the crystals and also differently affects the proton conductivity properties, measured over a wide range of temperature at 95% relative humidity. Their high thermal and chemical stability together with the small size may promote their use as fillers for polymeric electrolyte membranes for fuel cells applications.

  8. Nanosheets of Two-Dimensional Magnetic and Conducting Fe(II)/Fe(III) Mixed-Valence Metal-Organic Frameworks.

    Benmansour, Samia; Abhervé, Alexandre; Gómez-Claramunt, Patricia; Vallés-García, Cristina; Gómez-García, Carlos J


    We report the synthesis, magnetic properties, electrical conductivity, and delamination into thin nanosheets of two anilato-based Fe(II)/Fe(III) mixed-valence two-dimensional metal-organic frameworks (MOFs). Compounds [(H3O)(H2O)(phenazine)3][Fe(II)Fe(III)(C6O4X2)3]·12H2O [X = Cl (1) and Br (2)] present a honeycomb layered structure with an eclipsed packing that generates hexagonal channels containing the water molecules. Both compounds show ferrimagnetic ordering at ca. 2 K coexisting with electrical conductivity (with room temperature conductivities of 0.03 and 0.003 S/cm). Changing the X group from Cl to Br leads to a decrease in the ordering temperature and room temperature conductivity that is correlated with the decrease of the electronegativity of X. Despite the ionic charge of the anilato-based layers, these MOFs can be easily delaminated in thin nanosheets with the thickness of a few monolayers.

  9. Impact of Lead Acetate on Quantitative Consumption and Utilization of the Cotton Leaf Worm, Spodoptera littoralis (Boisduval, 1833 (Lepidoptera: Noctuidae

    Shahenda A. Abu ElEla


    Full Text Available The 3rd, 4th, 5th, and 6th instars of the cotton leaf worm Spodoptera littoralis (Boisduval, 1833 were treated with lead acetate, 100 mg lead [Pb (C2H3O24]/kg, using the leaf-dip method, toevaluate the effect of Pb on nutritional indices. The consumption index was significantly increasedat the 3rd and 6th instars. The growth rate significantly increased in 4th instars. The reverse wastrue in 6th instars. The absorptive capacity, in terms of approximate digestibility, wasinsignificantly changed in the entire instars. The food utilization efficiencies, in terms of theconversion of ingested (ECI and digested food (ECD to biomass, were significantly increased in4th instars. However, the ECD was significantly decreased in the 5th and 6th instars. In conclusion,treatment with lead may adversely affect the population biomass of S. littoralis due to the grossreduction in the final weight gain of larvae approaching to pupation. This might lead to reducedlevel of population size.

  10. Relative abundance of water-group ions in Saturn's inner magnetosphere

    Perry, Mark E.; Cravens, Thomas; Tokar, Robert; Smith, Howard T.; Perryman, Rebecca; Waite, J. Hunter; McNutt, Ralph L.


    At nineteen different times over seven years, the Cassini Ion Neutral Mass Spectrometer (INMS) measured the relative fractions of water-group ions in the inner magnetosphere of Saturn near the equatorial plane between 3.8 and 6.5 Saturn radii (RS). INMS samples only a small portion of velocity space in any one measurement, but the measurements span a broad range of velocity space. The data show that H2O+ comprises the bulk of the ions near 4.0 RS, and that its fraction decreases with increasing distance from 4.0 RS, the source of neutral water at Enceladus. At 4.0 RS, the fraction of H2O+ ranges from 60% to 100%, with an average of 80%. At 6.5 RS, the three main water-group constituents, H2O+, OH+, and O+, are nearly equal. H3O+, which dominates the water-group ion fractions in the Enceladus plume, is 10% or less in Saturn's magnetosphere outside the plume. The relative ion fractions show other variations that are not clearly linked to any of the studied parameters including velocity, density, and the orbit-phase-dependent activity of Enceladus.

  11. Proton Electrodynamics in Liquid Water

    Volkov, A A; Pronin, A V


    The dielectric spectrum of liquid water, $10^{4} - 10^{11}$ Hz, is interpreted in terms of diffusion of charges, formed as a result of self-ionization of H$_{2}$O molecules. This approach explains the Debye relaxation and the dc conductivity as two manifestations of this diffusion. The Debye relaxation is due to the charge diffusion with a fast recombination rate, $1/\\tau_{2}$, while the dc conductivity is a manifestation of the diffusion with a much slower recombination rate, $1/\\tau_{1}$. Applying a simple model based on Brownian-like diffusion, we find $\\tau_{2} \\simeq 10^{-11}$ s and $\\tau_{1} \\simeq 10^{-6}$ s, and the concentrations of the charge carriers, involved in each of the two processes, $N_{2} \\simeq 5 \\times 10^{26}$ m$^{-3}$ and $N_{1} \\simeq 10^{14}$ m$^{-3}$. Further, we relate $N_{2}$ and $N_{1}$ to the total concentration of H$_{3}$O$^{+}$--OH$^{-}$ pairs and to the pH index, respectively, and find the lifetime of a single water molecule, $\\tau_{0} \\simeq 10^{-9}$ s. Finally, we show that ...

  12. Understanding the spurious DFT fractional charge in the electrochemical double layer

    Chen, Leanne; Bajdich, Michal; Luntz, Alan; Chan, Karen; Norskov, Jens

    An ongoing challenge in computational electrochemistry is the accurate determination of electrochemical barriers at constant electrode potential. Recently, our group developed an efficient scheme to determine the barriers using a simple extrapolation based on the interfacial charge. However, semilocal DFT calculations have shown that the magnitude of the charge of solvated species (H3O+, OH-, Li+, Na+) in the outer Helmholtz plane is not 1e, but always near 0.6e, which suggests a charge delocalization error in DFT. Furthermore, we frequently observe inaccurate alignment of the metal Fermi and solvent energy levels. Using an increasing amount of exact exchange, we first analyze the charge delocalization error in the dissociation of NaCl molecule, where a large amount of exchange is need to reproduce the step-like transition of charge from +1 to 0 on the dissociated Na and Cl. Next, we apply the same method to the metal-water interface with solvated ions at varying distances from the surface. The performance of hybrid and other fractional charge-corrected functionals will be discussed together with the possibility of a simple correction scheme.

  13. Transformation of 1H-benzotriazole by ozone in aqueous solution.

    Mawhinney, Douglas B; Vanderford, Brett J; Snyder, Shane A


    Recent studies have shown that 1H-benzotriazole is a widespread contaminant of wastewater and surface water. Although disinfection by ozone has been shown to efficiently remove this compound, the transformation products have not been identified. To that end, the reaction of ozone with 1H-benzotriazole in aqueous solution has been studied in real time employing quadrupole time-of-flight mass spectrometry (Q-TOF MS) and negative electrospray ionization. The transformation products have been identified by calculating their empirical formulas using accurate mass measurements, and further confirmed by performing the reaction with stable isotope-labeled 1H-benzotriazole and measuring product ion spectra. Stable reaction products were distinguished from transient species by plotting their extracted mass profiles. The products that resulted from ozone and hydroxyl radicals in the reaction were qualitatively identified by modifying the conditions to either promote the formation of hydroxyl radicals, or to scavenge them. Based on experimental evidence, a mechanism for the direct reaction between ozone and 1H-benzotriazole is proposed that results in the formation of 1H-1,2,3-triazole-4,5-dicarbaldehyde, which has an empirical formula of C(4)H(3)O(2)N(3). Lastly, it was confirmed that the same transformation products formed in surface water and tertiary-treated wastewater, although they were observed to degrade at higher ozone doses.

  14. Modeling deoxyribose radicals by neutralization-reionization mass spectrometry. Part 2. Preparation, dissociations, and energetics of 3-hydroxyoxolan-3-yl radical and cation.

    Vivekananda, Shetty; Sadílek, Martin; Chen, Xiaohong; Adams, Luke E; Turecek, Frantisek


    The title radical (1) is generated in the gas-phase by collisional neutralization of carbonyl-protonated oxolan-3-one. A 1.5% fraction of 1 does not dissociate and is detected following reionization as survivor ions. The major dissociation of 1 (approximately 56%) occurs as loss of the hydroxyl H atom forming oxolan-3-one (2). The competing ring cleavages by O[bond]C-2 and C-4[bond]C-5 bond dissociations combined account for approximately 42% of dissociation and result in the formation of formaldehyde and 2-hydroxyallyl radical. Additional ring-cleavage dissociations of 1 resulting in the formation of C(2)H(3)O and C(2)H(4)O cannot be explained as occurring competitively on the doublet ground (X) electronic state of 1, but are energetically accessible from the A and higher electronic states accessed by vertical electron transfer. Exothermic protonation of 2 also produces 3-oxo-(1H)-oxolanium cation (3(+)) which upon collisional neutralization gives hypervalent 3-oxo-(1H)-oxolanium radical (3). The latter dissociates spontaneously by ring opening and expulsion of hydroxy radical. Experiment and calculations suggest that carbohydrate radicals incorporating the 3-hydroxyoxolan-3-yl motif will prefer ring-cleavage dissociations at low internal energies or upon photoexcitation by absorbing light at approximately 590 and approximately 400 nm.

  15. Widespread Rotationally-Hot Hydronium Ion in the Galactic Interstellar Medium

    Lis, D C; Bergin, E A; Gerin, M; Black, J H; Comito, C; De Luca, M; Godard, B; Higgins, R; Petit, F Le; Pearson, J C; Pellegrini, E W; Phillips, T G; Yu, S


    We present new observations of the (6,6) and (9,9) inversion transitions of the hydronium ion toward Sagittarius B2(N) and W31C. Sensitive observations toward Sagittarius B2(N) show that the high, ~ 500 K, rotational temperatures characterizing the population of the highly-excited metastable H3O+ rotational levels are present over a wide range of velocities corresponding to the Sagittarius B2 envelope, as well as the foreground gas clouds between the Sun and the source. Observations of the same lines toward W31C, a line of sight that does not intersect the Central Molecular Zone, but instead traces quiescent gas in the Galactic disk, also imply a high rotational temperature of ~ 380 K, well in excess of the kinetic temperature of the diffuse Galactic interstellar medium. While it is plausible that some fraction of the molecular gas may be heated to such high temperatures in the active environment of the Galactic center, characterized by high X-ray and cosmic ray fluxes, shocks and high degree of turbulence, t...

  16. Chemical tracers of high-metallicity environments

    Bayet, E; Bell, T A; Viti, S


    We present for the first time a detailed study of the properties of molecular gas in metal-rich environments such as early-type galaxies (ETGs). We have explored Photon-Dominated Region (PDR) chemistry for a wide range of physical conditions likely to be appropriate for these sources. We derive fractional abundances of the 20 most chemically reactive species as a function of the metallicity, as a function of the optical depth and for various volume number gas densities, Far-Ultra Violet (FUV) radiation fields and cosmic ray ionisation rates. We also investigate the response of the chemistry to the changes in $\\alpha-$element enhancement as seen in ETGs. We find that the fractional abundances of CS, H$_{2}$S, H$_{2}$CS, H$_{2}$O, H$_{3}$O$^{+}$, HCO$^{+}$ and H$_{2}$CN seem invariant to an increase of metallicity whereas C$^{+}$, CO, C$_{2}$H, CN, HCN, HNC and OCS appear to be the species most sensitive to this change. The most sensitive species to the change in the fractional abundance of $\\alpha-$elements ar...

  17. Herschel CHESS discovery of the fossil cloud that gave birth to the Trapezium and Orion KL

    López-Sepulcre, Ana; Ceccarelli, Cecilia; Dominik, Carsten; Caux, Emmanuel; Fuente, Asunción; Alonso-Albi, Tomás


    As part of the Herschel Guaranteed Time Key Programme CHESS, we present the discovery of a diffuse gas component in the foreground of the intermediate-mass protostar OMC-2 FIR 4, located in the Orion A region. Making use of the full HIFI spectrum of OMC-2 FIR 4 obtained in CHESS, we detected several ground-state lines from OH+, H2O+, HF, and CH+, all of them seen in absorption against the dust continuum emission of the protostar's envelope. The lines peak at a velocity of 9 km/s, which is blue-shifted by 2 km/s with respect to the systemic velocity of OMC-2 FIR 4 (V = 11.4 km/s). We derived column densities for each species, as well as an upper limit to the column density of the undetected H3O+. In order to model and characterise the foreground cloud, we used the Meudon PDR code to run a homogeneous grid of models that spans a reasonable range of densities, visual extinctions, cosmic ray ionisation rates and far-ultraviolet (FUV) radiation fields. The results of our modelling indicate that the foreground clou...

  18. Spatially extended OH+ emission from the Orion Bar and Ridge

    van der Tak, Floris; Ossenkopf, Volker; Makai, Zoltan; Black, John; Faure, Alex; Gerin, Maryvonne; Bergin, Ted


    We report the first detection of a Galactic source of OH+ line emission: the Orion Bar, a bright nearby photon-dominated region. Line emission is detected over ~1' (0.12 pc), tracing the Bar itself as well as the Southern tip of the Orion Ridge. The line width of ~4 km/s suggests an origin of the OH+ emission close to the PDR surface, at a depth of A_V ~0.3-0.5 into the cloud where most hydrogen is in atomic form. Steady-state collisional and radiative excitation models require unrealistically high OH+ column densities to match the observed line intensity, indicating that the formation of OH+ in the Bar is rapid enough to influence its excitation. Our best-fit OH+ column density of ~1x10^14 cm^-2 is similar to that in previous absorption line studies, while our limits on the ratios of OH+/H2O+ (>~40) and OH+/H3O+ (>~15) are higher than seen before. The column density of OH+ is consistent with estimates from a thermo-chemical model for parameters applicable to the Orion Bar, given the current uncertainties in ...

  19. Structural and Theoretical Evidence of the Depleted Proton Affinity of the N3-Atom in Acyclovir

    Esther Vílchez-Rodríguez


    Full Text Available The hydronium salt (H3O2[Cu(N7–acv2(H2O2(SO42]·2H2O (1, acv = acyclovir has been synthesized and characterized by single-crystal X-ray diffraction and spectral methods. Solvated Cu(OH2 is a by-product of the synthesis. In the all-trans centrosymmetric complex anion, (a the Cu(II atom exhibits an elongated octahedral coordination; (b the metal-binding pattern of acyclovir (acv consists of a Cu–N7(acv bond plus an (aquaO–H···O6(acv interligand interaction; and (c trans-apical/distal sites are occupied by monodentate O-sulfate donor anions. Neutral acyclovir and aqua-proximal ligands occupy the basal positions, stabilizing the metal binding pattern of acv. Each hydronium(1+ ion builds three H-bonds with O–sulfate, O6(acv, and O–alcohol(acv from three neighboring complex anions. No O atoms of solvent water molecules are involved as acceptors. Theoretical calculations of molecular electrostatic potential surfaces and atomic charges also support that the O-alcohol of the N9(acv side chain is a better H-acceptor than the N3 or the O-ether atoms of acv.

  20. Proton Transfer Time-of-Flight Mass Spectrometer

    Watson, Thomas B [Brookhaven National Lab. (BNL), Upton, NY (United States)


    The Proton Transfer Reaction Mass Spectrometer (PTRMS) measures gas-phase compounds in ambient air and headspace samples before using chemical ionization to produce positively charged molecules, which are detected with a time-of-flight (TOF) mass spectrometer. This ionization method uses a gentle proton transfer reaction method between the molecule of interest and protonated water, or hydronium ion (H3O+), to produce limited fragmentation of the parent molecule. The ions produced are primarily positively charged with the mass of the parent ion, plus an additional proton. Ion concentration is determined by adding the number of ions counted at the molecular ion’s mass-to-charge ratio to the number of air molecules in the reaction chamber, which can be identified according to the pressure levels in the reaction chamber. The PTRMS allows many volatile organic compounds in ambient air to be detected at levels from 10–100 parts per trillion by volume (pptv). The response time is 1 to 10 seconds.

  1. Crystal structure of a compact three-dimensional metal–organic framework based on Cs+ and (4,5-dicyano-1,2-phenylenebis(phosphonic acid

    Ricardo F. Mendes


    Full Text Available A new metal–organic framework compound, poly[[μ7-dihydrogen (4,5-dicyano-1,2-phenylenediphosphonato](oxoniumcaesium], [Cs(C8H4N2O6P2(H3O]n (I, based on Cs+ and the organic linker 4,5-dicyano-1,2-phenylenebis(phosphonic acid, (H4cpp, containing two distinct coordinating functional groups, has been prepared by a simple diffusion method and its crystal structure is reported. The coordination polymeric structure is based on a CsO8N2 complex unit comprising a monodentate hydronium cation, seven O-atom donors from two phosphonium groups of the (H2cpp2− ligand, and two N-atom donors from bridging cyano groups. The high level of connectivity from both the metal cation and the organic linker allow the formation of a compact and dense three-dimensional network without any crystallization solvent. Topologically (I is a seven-connected uninodal network with an overall Schäfli symbol of {417.64}. Metal cations form an undulating inorganic layer, which is linked by strong and highly directional O—H...O hydrogen-bonding interactions. These metallic layers are, in turn, connected by the organic ligands along the [010] direction to form the overall three-dimensional framework structure.

  2. Secondary organic material formed by methylglyoxal in aqueous aerosol mimics

    N. Sareen


    Full Text Available We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The kinetics were characterized using UV-Vis spectrophotometry. The results suggest that the bimolecular reaction of methylglyoxal with an ammonium or hydronium ion is the rate-limiting step for the formation of light-absorbing species, with kNH4+II=5×10−6 M−1 min−1 and kH3O+II≤10−3 M−1 min−1. Evidence of aldol condensation products and oligomeric species up to 759 amu was found using chemical ionization mass spectrometry with a volatilization flow tube inlet (Aerosol-CIMS. Tentative identifications of carbon-nitrogen species and a sulfur-containing compound were also made using Aerosol-CIMS. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit significant surface tension depression. These observations add to the growing body of evidence that dicarbonyl compounds may form secondary organic material in the aerosol aqueous phase, and that secondary organic aerosol formation via heterogeneous processes may affect seed aerosol properties.

  3. Photoluminescence on cerium-doped ZnO nanorods produced under sequential atomic layer deposition-hydrothermal processes

    Cervantes-López, J. L.; Rangel, R.; Espino, J.; Martínez, E.; García-Gutiérrez, R.; Bartolo-Pérez, P.; Alvarado-Gil, J. J.; Contreras, O. E.


    Doped and undoped ZnO nanorod arrays were produced combining atomic layer deposition and hydrothermal processes. First, a ZnO layer with preferential orientation normal to the c-axis was grown on the substrate by means of the decomposition of diethylzinc; subsequently, the nanorod arrays were produced through solvothermal process using a solution of Zn(NO3)2 as precursor. Doped ZnO nanorods were produced using Ce(C2H3O2)3·H2O as dopant agent precursor. Undoped and Ce-doped ZnO nanorod arrays showed high-intensity photoluminescence. The doping concentration of x = 0.04 (Zn1- x Ce x O) displayed the highest photoluminescence. Undoped ZnO showed an intense UV peak centered at 382 nm with a narrow full wide half maximum of 33 nm. Ce-doped ZnO PL spectra contain three bands, one signal in the UV region centered at 382 nm, other centered at 467 nm in the near-green region and other one emission centered at 560 nm. The results herein exposed demonstrate the capability to produce high-quality ZnO and Zn1- x Ce x O films.

  4. Dye-sensitized solar cell characteristics of nanocomposite zinc ferrite working electrode: effect of composite precursors and titania as a blocking layer on photovoltaic performance.

    Habibi, Mohammad Hossein; Habibi, Amir Hossein; Zendehdel, Mahmoud; Habibi, Mehdi


    This research investigates the performance of a zinc ferrite (ZF) as working electrodes in a dye-sensitized solar cell (DSSC). This ZF working electrode was prepared by sol-gel and thermal decomposition of four different precursors including: zinc acetate dihydrate (Zn(CH3COO)2·2H2O), ferric nitrate nonahydrate (Fe(NO3)3·9H2O), iron(III) acetate; Fe(C2H3O2)3, and zinc nitrate hexahydrate, Zn(NO3)2·6H2O. The effects of annealing temperature and precursors on the structural, morphological, and optical properties were investigated. The field emission scanning electron microscope images (FESEM) and scanning electron microscopy (SEM) show that ZFe films are polycrystalline in nature and homogeneous with densely packed grains. Nanoporous zinc ferrite coatings were prepared by doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in DSSC. In all DSSCs, platinized FTO and [Co(bpy)3](2+/3+) in 3-methoxy proponitrile were used as counter electrode and redox mediator system respectively. Comparing the fill factors of four different zinc ferrite nanocomposites, the highest fill factor was for ZnFe2O4-TBL sample. Cell fabricated with ZnFeA working electrode shows relatively higher Jsc.

  5. Electric-Field-Enhanced Jumping-Droplet Condensation

    Miljkovic, Nenad; Preston, Daniel; Enright, Ryan; Limia, Alexander; Wang, Evelyn


    When condensed droplets coalesce on a superhydrophobic surface, the resulting droplet can jump due to the conversion of surface energy into kinetic energy. This frequent out-of-plane droplet jumping has the potential to enhance condensation heat and mass transfer. In this work, we demonstrated that these jumping droplets accumulate positive charge that can be used to further increase condensation heat transfer via electric fields. We studied droplet jumping dynamics on silanized nanostructured copper oxide surfaces. By characterizing the droplet trajectories under various applied external electric fields (0 - 50 V/cm), we show that condensation on superhydrophobic surfaces results in a buildup of negative surface charge (OH-) due to dissociated water ion adsorption on the superhydrophobic coating. Consequently, the opposite charge (H3O +) accumulates on the coalesced jumping droplet. Using this knowledge, we demonstrate electric-field-enhanced jumping droplet condensation whereby an external electric field opposes the droplet vapor flow entrainment towards the condensing surface to increase the droplet removal rate and overall surface heat transfer by 100% when compared to state-of-the-art dropwise condensing surfaces. This work not only shows significant condensation heat transfer enhancement through the passive charging of condensed droplets, but promises a low cost approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification.

  6. Controlled surface adsorption of fd filamentous phage by tuning of the pH and the functionalization of the surface

    Jeon, Dae-Young; Hwang, Kyung Hoon; Park, So-Jeong; Kim, Yun-Jeong; Joo, Min-Kyu; Ahn, Seung-Eon; Kim, Gyu-Tae; Nam, Chang-Hoon


    The surface adsorption of fd filamentous phage (fd phage) dispersed in different solution pHs was investigated with functionalized SiO2/Si substrates. The fd phages at high pH (˜9.0) were well-adsorbed on the SiO2/Si surface that was functionalized by 3-aminopropyltriethoxysilane, whereas those at low pH (˜3.0) were well-adsorbed on the cleaned SiO2/Si surface. The high affinity of the carboxylic acid groups (COO-) at high pH (˜9.0) was attributed to the fact that they give a higher adsorption to the positively charged amine groups (NH3+) on the surface of the substrate, similar to the effect of H3O+ at low pH (˜3.0) in a solution on the surface of the hydroxyl groups on the substrate (OH-). Interestingly, the aligned structures of the fd phage at intermediate pH (˜7.0), caused by the locally positively charged coat protein of the fd phage and the shear forces along the washing and blowing direction, were identified. The effective spring constant of the fd phage bundles was estimated to be 0.672 N/m using a force-distance curve. Our results offer prerequisite information for the bottom-up assembly in SiO2/Si substrates using the fd phage in bionanoelectronics.

  7. Comparison of hydrolysis kinetics of different vegetable oils in near-critical water%不同植物油脂在近临界水中水解反应动力学的比较

    孙辉; 吕秀阳; 陈良


    @@ 引言 近临界水(near-critical water,NCW)通常是指温度在200~350℃之间的压缩液态水.近临界水中的[H3O+]和[OH-]已接近弱酸或弱碱,因此自身具有酸催化与碱催化的功能,可使某些酸碱催化反应不必加入酸碱催化剂;NCW具有足够小的介电常数,具有能同时溶解有机物和无机物的特性.同时,近临界水还具有优良的传质性能及绿色环保等优点,因而在有机化学反应、废弃物再资源化等领域得到了较广泛的研究[1].

  8. Reductive dissolution of Tl(I)-jarosite by Shewanella putrefaciens: providing new insights into Tl biogeochemistry.

    Smeaton, Christina M; Walshe, Gillian E; Fryer, Brian J; Weisener, Christopher G


    Thallium (Tl) is emerging as a metal of concern in countries such as China due to its release during the natural weathering of Tl-bearing ore deposits and mining activities. Despite the high toxicity of Tl, few studies have examined the reductive dissolution of Tl mineral phases by microbial populations. In this study we examined the dissolution of synthetic Tl(I)-jarosite, (H(3)O)(0.29)Tl(0.71)Fe(2.74)(SO(4))(2)(OH)(5.22)(H(2)O)(0.78), by Shewanella putrefaciens CN32 using batch experiments under anaerobic circumneutral conditions. Fe(II) concentrations were measured over time and showed Fe(II) production (4.6 mM) in inoculated samples by 893 h not seen in mineral and dead cell controls. Release of aqueous Tl was enhanced in inoculated samples whereby maximum concentrations in inoculated and cell-free samples reached 3.2 and 2.1 mM, respectively, by termination of the experiment. Complementary batch Tl/S. putrefaciens sorption experiments were conducted under experimentally relevant pH (5 and 6.3) at a Tl concentration of 35 μM and did not show significant Tl accumulation by either live or dead cells. Therefore, in contrast to many metals such as Pb and Cd, S. putrefaciens does not represent a sink for Tl in the environment and Tl is readily released from Tl-jarosite during both abiotic and biotic dissolution.

  9. First examples of extended structures based on {PMo(12)Sb(2)O(40)} polyoxoanions.

    Shi, Shu-Yun; Sun, Ying-Hua; Chen, Yan; Xu, Jia-Ning; Cui, Xiao-Bing; Wang, Yan; Wang, Guo-Wu; Yang, Guang-Di; Xu, Ji-Qing


    Three novel heteropolyanions [PMo(12)Sb(2)O(40)][Cu(enMe)(2)].4H(2)O (), [PMo(12)Sb(2)O(40)][Ni(enMe)(2)].4H(2)O (2) and [PMo(12)Sb(2)O(40)][Cu(en)(2)].H(3)O.H(2)O (3) (enMe = 1,2-diaminopropane, en = ethylene diamine) have been synthesized and characterized by IR spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses and elemental analyses. Single-crystal X-ray diffraction analyses reveal that these three compounds represent the first examples of compounds based on the novel polyoxoanion {PMo(12)Sb(2)O(40)} and different transition metal coordination complexes. 1 and 2 are isostructural and both exhibit novel 1-D structures. In contrast to 1 and 2, 3 exhibits a substantially distinct novel 1-D structure. In addition, 3 is the first example of an extended structure constructed from polyoxoanions and Cu(+) transition metal coordination complexes.

  10. Molecular formation along the atmospheric mass loss of HD 209458 b and similar Hot Jupiters

    Pinotti, Rafael


    The chemistry along the mass loss of Hot Jupiters is generally considered to be simple, consisting mainly of atoms, prevented from forming more complex species by the intense radiation field from their host stars. In order to probe the region where the temperature is low (T < 2000 K), we developed a 1D chemical and photochemical reaction model of the atmospheric mass loss of HD 209458 b, involving 56 species, including carbon chain and oxygen bearing ones, interacting through 566 reactions. The simulation results indicate that simple molecules like OH+, H2O+ and H3O+ are formed inside the region, considering that residual H2 survives in the exosphere, a possibility indicated by recent observational work. The molecules are formed and destroyed within a radial distance of less than 10^7 km, but the estimated integrated column density of OH+, a potential tracer of H2, is high enough to allow detection, which, once achieved, would indicate a revision of chemical models of the upper atmosphere of Hot Jupiters. ...

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

    Bu, Wei; Vaknin, David; Travesset, Alex


    Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface. A lipid phosphate (dihexadecyl hydrogen-phosphate) was spread as a monolayer at the air-water interface to control surface charge density. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. Five decades in bulk concentrations are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. The increase of Cs+ concentration modifies the contact value potential, thereby causing proton release. This process effectively modifies surface charge density and enables exploration of ion distributions as a function of effective surface charge-density. The experimentally obtained ion distributions are compared to distributions calculated by Poisson-Boltzmann theory accounting for the variation of surface charge density due to proton release and binding. We also discuss the accuracy of our experimental results in discriminating possible deviations from Poisson-Boltzmann theory.

  12. 5-Amino-6-methylquinolin-1-ium hydrogen malonate–malonic acid (2/1

    Ibrahim Abdul Razak


    Full Text Available The asymmetric unit of the title compound, 2C10H11N2+·2C3H3O4−·C3H4O4, consists of one 5-amino-6-methylquinolin-1-ium cation, one hydrogen malonate (2-carboxyacetate anion and one-half molecule of malonic acid which lies on a twofold rotation axis. The quinoline ring system is essentially planar, with a maximum deviation of 0.062 (2 Å for all non-H atoms. In the anion, an intramolecular O—H...O hydrogen bond generates an S(6 ring. In the crystal, the components are linked via N—H...O and O—H...O hydrogen bonds into layers parallel to the ac plane. The crystal structure also features weak C—H...O hydrogen bonds and a π–π stacking interaction with a centroid–centroid distance of 3.8189 (10 Å.

  13. Crystal structure of poly[diaqua(μ-2-carboxyacetato-κ3O,O′:O′′(2-carboxyacetato-κOdi-μ-chlorido-dicobalt(II

    Yasmina Bouaoud


    Full Text Available The asymmetric unit of the title polymer, [Co2(C3H3O42Cl2(H2O2]n, comprises one CoII atom, one water molecule, one singly deprotonated malonic acid molecule (HMal−; systematic name 2-carboxyacetate and one Cl− anion. The CoII atom is octahedrally coordinated by the O atom of a water molecule, by one terminally bound carboxylate O atom of an HMal− anion and by two O atoms of a chelating HMal− anion, as well as by two Cl− anions. The Cl− anions bridge two CoII atoms, forming a centrosymmetric Co2Cl2 core. Each malonate ligand is involved in the formation of six-membered chelate rings involving one CoII atom of the dinuclear unit and at the same time is coordinating to another CoII atom of a neighbouring dinuclear unit in a bridging mode. The combination of chelating and bridging coordination modes leads to the formation of a two-dimensional coordination polymer extending parallel to (001. Within a layer, O—Hwater...Cl and O—Hwater...O hydrogen bonds are present. Adjacent layers are linked through O—H...O=C hydrogen bonds involving the carboxylic acid OH and carbonyl groups.

  14. Ionization of the group 3 metals La, Y and Sc in H2---O2---Ar flames

    Patterson, Patricia M.; Goodings, John M.


    Four pairs of premixed, fuel-rich/fuel-lean (FR/FL; equivalence ratio [Phi] = 1.5/0.75). H2---O2---Ar flames at four temperatures in the range 1900-2425 K, all at atmospheric pressure, were doped with about 10-6 mole fraction of the group 3 metals La, Y and Sc using atomizer techniques. The metals produce solid particles in the flames and gaseous metallic species. The latter include free metallic atoms, A, near the flame reaction zone, but only the monoxide AO and the oxide-hydroxide OAOH further downstream at equilibrium; the [OAOH]/[AO] ratio varies in FR/FL flames. Metallic ions (produce AO+; further downstream, the ionization level is sustained by the thermal (collisional) ionization of AO to produce AO+ and/or the chemi-ionization of OAOH with H to produce A(OH)2+. The ions AO+, A(OH)2+ and higher hydrates are all rapidly equilibrated by three-body association reactions with water. Ions are lost by dissociative electron-ion recombination of A(OH)2+ and possibly higher hydrates. The chemical ionization of the metallic species by H3O+ was investigated by adding a small quantity of CH4 to the flames. The ion chemistry is discussed in detail. An estimate of the bond dissociation energy D0°(OLa---OH) = 408 ± 40 kJ mol-1 (4.23 ± 0.41 eV) was obtained.

  15. Dynamical conductivity of confined water

    Artemov, V. G.


    The electrodynamic response of water confined in nanoporous MCM-41 is measured in the frequency range 1 MHz-3 THz at room temperature. The results are analyzed in the context of a recently proposed ionic model of water. We found an increase in dc-conductivity of confined water by 3 orders of magnitude (3.3 · 10-3 Ω-1 · m-1) compared to bulk water (5.5 · 10-6 Ω-1 · m-1). This is attributed to the increase of H3O+ and OH- ion mobility, due to a decrease of the effective potential amplitude by walls of the confining environment. We found that the absorption in the microwave frequency range is much smaller in the medium with confined water than in the bulk water, and the quadratic dependence of the conductivity (σ) on frequency (ω) becomes less steep and tends to σ ~ ω. The results are of fundamental importance and can be used for understanding of the proton transport in systems with water in the nanoconfined state.

  16. Photoluminescence Probing of Complex H2O Adsorption on InGaN/GaN Nanowires.

    Maier, Konrad; Helwig, Andreas; Müller, Gerhard; Hille, Pascal; Teubert, Jörg; Eickhoff, Martin


    We demonstrate that the complex adsorption behavior of H2O on InGaN/GaN nanowire arrays is directly revealed by their ambient-dependent photoluminescence properties. Under low-humidity, ambient-temperature, and low-excitation-light conditions, H2O adsorbates cause a quenching of the photoluminescence. In contrast, for high humidity levels, elevated temperature, and high excitation intensity, H2O adsorbates act as efficient photoluminescence enhancers. We show that this behavior, which can only be detected due to the low operation temperature of the InGaN/GaN nanowires, can be explained on the basis of single H2O adsorbates forming surface recombination centers and multiple H2O adsorbates forming surface passivation layers. Reversible creation of such passivation layers is induced by the photoelectrochemical splitting of adsorbed water molecules and by the interaction of reactive H3O(+) and OH(-) ions with photoactivated InGaN surfaces. Due to electronic coupling of adsorbing molecules with photoactivated surfaces, InGaN/GaN nanowires act as sensitive nanooptical probes for the analysis of photoelectrochemical surface processes.

  17. 4-Chloroanilinium 3-carboxyprop-2-enoate

    R. Anitha


    Full Text Available In the title compound, C6H7ClN+·C4H3O4−, the cations and anions lie on mirror planes and hence only half of the molecules are present in the asymmeric unit. The 4-chloroanilinium cation and hydrogen maleate anion in the asymmetric unit are each planar and are oriented at an angle of 15.6 (1° to one another and perpendicular to the b axis. A characterestic intramolecular O—H...O hydrogen bond, forming an S(7 motif, is observed in the maleate anion. In the crystal, the cations and anions are linked by N—H...O hydrogen bonds, forming layers in the ab plane. The aromatic rings of the cations are sandwiched between hydrogen-bonded chains and rings formed through the amine group of the cation and maleate anions, leading to alternate hydrophobic (z = 0 or 1 and hydrophilic layers (z = 1/2 along the c axis.

  18. Solvothermal synthesis and theoretical study of a polypyridium trimesylate adduct

    Yulan Zhu; Feng Ma; Kuirong Ma; Li Cao; Lianhua Zhao


    The title compound (C9H3O6·C20H17N4)4·0.5H2O 1 was isolated from solvothermal synthesis of 4'-(4-pyridyl)-2,2':6',2'-terpyridine (pytpy) and trimesic acid (1,3,5-benzenetricarboxylic acid, H3BTC). It was characterized by element analysis, IR, TGA, XRD, X-ray single-crystal diffraction, and spectroscopy properties, together with quantum chemistry calculation of spectrum (UV-vis spectra) through the method b3lyp/6-31 t g (d,p) are also investigated. Single-crystal X-ray diffraction shows 1 possesses a 3-D supramolecular network with 1-D six-fold helical double chains built from protonated (H3pytpy)$^{3+}_{n}$ cations and deprotonated (BTC)$^{3−}_{n}$ anions. The maximum of the fluorescent emission bands of 1 is located at 427 nm (ex = 266 nm), with a shoulder at about 390 nm. The result of theoretic calculations confirms that 1 has small HOMO-LUMO energy gap (1.24 eV) and high chemical reactivity.

  19. Organic Carbonates: Efficient Extraction Solvents for the Synthesis of HMF in Aqueous Media with Cerium Phosphates as Catalysts.

    Dibenedetto, Angela; Aresta, Michele; di Bitonto, Luigi; Pastore, Carlo


    We describe a process for the selective conversion of C6 -polyols into 5-hydroxymethylfurfural (5-HMF) in biphasic systems of organic carbonate/water (OC/W), with cerium(IV) phosphates as catalysts. Different reaction parameters such as the OC/W ratio, catalyst loading, reaction time, and temperature, were investigated for the dehydration of fructose. Under the best reaction conditions, a yield of 67.7 % with a selectivity of 93.2 % was achieved at 423 K after 6 h of reaction using [(Ce(PO4)1.5 (H2 O)(H3 O)0.5 (H2 O)0.5)] as the catalyst. A maximum yield of 70 % with the same selectivity was achieved after 12 h. At the end of the reaction, the catalyst was removed by centrifugation, the organic phase was separated from water and evaporated in vacuo (with solvent recovery), and solid 5-HMF was isolated (purity >99 %). The recovery and reuse of the catalyst and the relationship between the structure of the OC and the efficiency of the extraction are discussed. The OC/W system influences the lifetime of the catalysts positively compared to only water.

  20. Atmospheric pressure plasma jets interacting with liquid covered tissue: touching and not-touching the liquid

    Norberg, Seth A.; Tian, Wei; Johnsen, Eric; Kushner, Mark J.


    In the use of atmospheric pressure plasma jets in biological applications, the plasma-produced charged and neutral species in the plume of the jet often interact with a thin layer of liquid covering the tissue being treated. The plasma-produced reactivity must then penetrate through the liquid layer to reach the tissue. In this computational investigation, a plasma jet created by a single discharge pulse at three different voltages was directed onto a 200 µm water layer covering tissue followed by a 10 s afterglow. The magnitude of the voltage and its pulse length determined if the ionization wave producing the plasma plume reached the surface of the liquid. When the ionization wave touches the surface, significantly more charged species were created in the water layer with H3O+aq, O3-aq, and O2-aq being the dominant terminal species. More aqueous OHaq, H2O2aq, and O3aq were also formed when the plasma plume touches the surface. The single pulse examined here corresponds to a low repetition rate plasma jet where reactive species would be blown out of the volume between pulses and there is not recirculation of flow or turbulence. For these conditions, NxOy species do not accumulate in the volume. As a result, aqueous nitrites, nitrates, and peroxynitrite, and the HNO3aq and HOONOaq, which trace their origin to solvated NxOy, have low densities.

  1. PTR3: An Instrument for Studying the Lifecycle of Reactive Organic Carbon in the Atmosphere.

    Breitenlechner, Martin; Fischer, Lukas; Hainer, Markus; Heinritzi, Martin; Curtius, Joachim; Hansel, Armin


    We have developed and characterized the novel PTR3, a proton transfer reaction-time-of-flight mass spectrometer (PTR-TOF) using a new gas inlet and an innovative reaction chamber design. The reaction chamber consists of a tripole operated with rf voltages generating an electric field only in the radial direction. An elevated electrical field is necessary to reduce clustering of primary hydronium (H3O(+)) and product ions with water molecules present in the sample gas. The axial movement of the ions is achieved by the sample gas flow only. Therefore, the new design allows a 30-fold longer reaction time and a 40-fold increase in pressure compared to standard PTR-TOF-MS. First calibration tests show sensitivities of up to 18000 counts per second/parts per billion and volume (cps/ppbv) at a mass resolution of >8000 m/Δm (fwhm). The new inlet using center-sampling through a critical orifice reduces wall losses of low volatility compounds. Therefore, the new PTR3 instrument is sensitive to VOC typically present in the ppbv range as well as to semivolatile organic compounds (SVOC) and even highly oxidized organic molecules (HOMs) present in the parts per quadrillion per volume (ppqv) range in the atmosphere.

  2. Taylor O(h³) Discretization of ZNN Models for Dynamic Equality-Constrained Quadratic Programming With Application to Manipulators.

    Liao, Bolin; Zhang, Yunong; Jin, Long


    In this paper, a new Taylor-type numerical differentiation formula is first presented to discretize the continuous-time Zhang neural network (ZNN), and obtain higher computational accuracy. Based on the Taylor-type formula, two Taylor-type discrete-time ZNN models (termed Taylor-type discrete-time ZNNK and Taylor-type discrete-time ZNNU models) are then proposed and discussed to perform online dynamic equality-constrained quadratic programming. For comparison, Euler-type discrete-time ZNN models (called Euler-type discrete-time ZNNK and Euler-type discrete-time ZNNU models) and Newton iteration, with interesting links being found, are also presented. It is proved herein that the steady-state residual errors of the proposed Taylor-type discrete-time ZNN models, Euler-type discrete-time ZNN models, and Newton iteration have the patterns of O(h(3)), O(h(2)), and O(h), respectively, with h denoting the sampling gap. Numerical experiments, including the application examples, are carried out, of which the results further substantiate the theoretical findings and the efficacy of Taylor-type discrete-time ZNN models. Finally, the comparisons with Taylor-type discrete-time derivative model and other Lagrange-type discrete-time ZNN models for dynamic equality-constrained quadratic programming substantiate the superiority of the proposed Taylor-type discrete-time ZNN models once again.

  3. WISH VI. Constraints on UV and X-ray irradiation from a survey of hydrides in low- to high-mass YSOs

    Benz, A O; van Dishoeck, E F; Melchior, M; Wampfler, S F; van der Tak, F; Goicoechea, J R; Indriolo, N; Kristensen, L E; Lis, D C; Mottram, J C; Bergin, E A; Caselli, P; Herpin, F; Hogerheijde, M R; Johnstone, D; Liseau, R; Nisini, B; Tafalla, M; Visser, R; Wyrowski, F


    Hydrides are simple compounds containing one or a few hydrogen atoms bonded to a heavier atom. They are fundamental precursor molecules in cosmic chemistry and many hydride ions have become observable in high quality for the first time thanks to the Herschel Space Observatory. Ionized hydrides, such as CH+ and OH+, and also HCO+ that affect the chemistry of molecules such as water, provide complementary information on irradiation by far UV (FUV) or X-rays and gas temperature. The targeted lines of CH+, OH+, H2O+, C+ and CH are detected mostly in blue-shifted absorption. H3O+ and SH+ are detected in emission and only toward some high-mass objects. The observed line parameters and correlations suggest two different origins, related to gas entrained by the outflows and to the circumstellar envelope. The column density ratios of CH+/OH+ are estimated from chemical slab models, assuming that the H2 density is given by the specific density model of each object at the beam radius. For the low-mass YSOs the observed ...

  4. Kinetic Isotope Effect on Transport Mediated by Clc-Type H+/CL- Exchangers

    Picollo, Alessandra; Malvezzi, Mattia; Accardi, Alessio


    CLC transporters mediate the stoichiometric exchange of 2 Cl- ions for 1 H+ across the membranes of cellular compartments, mostly endosomes and lysosomes. Despite intense biophysical, structural and electrophysiological scrutiny the H+ transfer mechanism of these exchangers remains largely unknown. Previous work showed that two conserved Glutamates define the extremities of the H+ pathway in CLC exchangers. However, we don't know whether H+ transfer between these residues takes place along a series of protonatable moieties, via a Grotthuss mechanism and by diffusion of an H3+O cation and if at any step H+ tunneling plays a role. To differentiate between these possible mechanisms we measured the deuterium kinetic isotope effect on the transport rate of CLC-ec1 and CLC-5, respectively a prokaryotic and a eukaryotic CLC exchanger. We found that transport mediated by both proteins is slowed by ˜20-40% when H2O is replaced by D2O. This result suggests that the rate limiting step for H+ transport takes place along a hydrogen-bonded pathway, possibly formed by water molecules. However, we found that the voltage dependence of CLC-5 inhibition by extracellular H+ is eliminated by this substitution. This suggests that the voltage dependence of this process arises from a mechanism that is exquisitely sensitive to particle mass such as proton tunneling.

  5. Adsorbent-adsorbate interactions in the adsorption of Cd(II) and Hg(II) on ozonized activated carbons.

    Sánchez-Polo, M; Rivera-Utrilla, J


    The present work investigated the effect of surface oxygenated groups on the adsorption of Cd(II) and Hg(II) by activated carbon. A study was undertaken to determine the adsorption isotherms and the influence of the pH on the adsorption of each metallic ion by a series of ozonized activated carbons. In the case of Cd(II), the adsorption capacity and the affinity of the adsorbent augmented with the increase in acid-oxygenated groups on the activated carbon surface. These results imply that electrostatic-type interactions predominate in this adsorption process. The adsorption observed at solution pH values below the pH(PZC) of the carbon indicates that other forces also participate in this process. Ionic exchange between -C pi-H3O+ interaction protons and Cd(II) ions would account for these findings. In the case of Hg(II), the adsorption diminished with an increase in the degree of oxidation of the activated carbon. The presence of electron-withdrawing groups on oxidized carbons decreases the electronic density of their surface, producing a reduction in the adsorbent-adsorbate dispersion interactions and in their reductive capacity, thus decreasing the adsorption of Hg(II) on the activated carbon. At pH values above 3, the pH had no influence on the adsorption of Hg(II) by the activated carbon, confirming that electrostatic interactions do not have a determinant influence on Hg(II) adsorption.

  6. Probe beam deflection studies of nanostructured catalyst materials for fuel cells.

    García, G; Bruno, M M; Planes, G A; Rodriguez, J L; Barbero, C A; Pastor, E


    Probe beam deflection (PBD) techniques, both as cyclic voltadeflectometry (CVD) and chronodeflectometry (CD), were applied for the first time to the study of the electrochemistry of nanostructured Pt materials which are commonly used as electrocatalysts in fuel cells. The electrochemical surface reactions, including faradaic processes, double layer charging and specific anion adsorption were easily detected. Quantitative analysis of the chronodeflectometric data made possible to elucidate the dynamics of double layer charging in such materials and to determine the potential of zero charge (pzc) of the metal present either as a monolithic mesoporous material or as metal nanoparticles supported on carbon. The electro-oxidation of CO, adsorbed on nanostructured Pt, was also studied by CVD and CD being able to detect the formation of CO2 and H3O+ related with the nucleation and growth process which controls the rate of CO stripping. The interplay of Pt oxide formation and COad electrooxidation, both in potential and time, was detected indicating possible application of the technique to other electrocatalysts.

  7. Crystal structure of poly[bis(ammonium [bis(μ4-benzene-1,3,5-tricarboxylatodizincate] 1-methylpyrrolidin-2-one disolvate

    Carlos Ordonez


    Full Text Available The title three-dimensional metal–organic framework (MOF compound, {(NH42[Zn2(C9H3O62]·2C5H9NO}n, features an anionic framework constructed from Zn2+ cations and benzene-1,3,5-tricarboxylate (BTC organic anions. Charge balance is achieved by outer sphere ammonium cations formed by degradation of di-n-butylamine in the solvothermal synthesis of the compound. Binuclear {Zn2(COO2} entities act as the framework's secondary building units. Each ZnII atom has a tetrahedral coordination environment with an O4 set of donor atoms. The three-dimensional framework adopts a rutile-type topology and channels are filled in an alternating fashion with ordered and disordered 1-methylpyrrolidin-2-one solvent molecules and ammonium cations. The latter are held in the channels via four N—H...O hydrogen bonds, including three with the benzene-1,3,5-tricarboxylate ligands of the anionic framework and one with a 1-methylpyrrolidin-2-one solvent molecule.

  8. Matrix composition and community structure analysis of a novel bacterial pyrite leaching community.

    Ziegler, Sibylle; Ackermann, Sonia; Majzlan, Juraj; Gescher, Johannes


    Here we describe a novel bacterial community that is embedded in a matrix of carbohydrates and bio/geochemical products of pyrite (FeS(2)) oxidation. This community grows in stalactite-like structures--snottites--on the ceiling of an abandoned pyrite mine at pH values of 2.2-2.6. The aqueous phase in the matrix contains 200 mM of sulfate and total iron concentrations of 60 mM. Micro-X-ray diffraction analysis showed that jarosite [(K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6)] is the major mineral embedded in the snottites. X-ray absorption near-edge structure experiments revealed three different sulfur species. The major signal can be ascribed to sulfate, and the other two features may correspond to thiols and sulfoxides. Arabinose was detected as the major sugar component in the extracellular polymeric substance. Via restriction fragment length polymorphism analysis, a community was found that mainly consists of iron oxidizing Leptospirillum and Ferrovum species but also of bacteria that could be involved in dissimilatory sulfate and dissimilatory iron reduction. Each snottite can be regarded as a complex, self-contained consortium of bacterial species fuelled by the decomposition of pyrite.

  9. A far-infrared molecular and atomic line survey of the Orion KL region

    Lerate, M R; Swinyard, B M; Goicoechea, J R; Cernicharo, J; Grundy, T W; Lim, T L; Polehampton, E T; Baluteau, J P; Viti, S; Yates, J


    We have carried out a high spectral resolution line survey towards the Orion Kleinmann-Low (KL) cluster from 44-188 um. The observations were taken with the Long Wavelength Spectrometer (LWS) in Fabry-Perot mode, on board the Infrared Space Observatory (ISO). A total of 152 lines are clearly detected and a further 34 features are present as possible detections. The spectrum is dominated by the molecular species H2O, OH and CO, along with [OI] and [CII] lines from PDR or shocked gas and [OIII], [NIII] lines from the foreground M42 HII region. Several isotopic species, as well as NH3, are also detected. HDO and H3O+ are tentatively detected for the first time in the far-infrared range towards Orion-KL. A basic analysis of the line observations is carried out, by comparing with previous measurements and published models and deriving rotational temperatures and column densities in the case of the molecular species. The complexity of the region requires more sophisticated models for the interpretation of all the l...

  10. Synthesis and structures of new hybrid fluorides templated by tetraprotonated pentaerythrityl tetramine

    Adil, K.; Goreshnik, E.; Courant, S.; Dujardin, G.; Leblanc, M.; Maisonneuve, V.


    A new route to synthetize the pentaerythrityl tetramine ( tetra), C(CH 2NH 2) 4, is established with a good overall yield (75-80%) and four hybrid fluorides, templated by tetra, are synthetized by hydrothermal technique and microwave heating: cis-[H 4tetra]•(AlF 5) 2 ( I), trans-[H 4tetra]•(AlF 5) 2 ( II), [H 4tetra]•(AlF 6)•(Cl) ( III) and (H 3O)•[H 4tetra] 2•(Ga(OH) 2F 4)•(GaF 6) 2•2H 2O ( IV). Structural determinations are performed from single crystal X-ray diffraction data. Structures of I and II are built up from infinite (∞ chains of corner sharing AlF 6 octahedra; the octahedra are cis-connected in I and trans-connected in II. III and IV are molecular phases and consist of isolated AlF 6 ( III) or Ga(OH) 2F 4 and GaF 6 ( IV) octahedra. Isolated chloride ions are found in III. Charge balance is ensured by tetraprotonated amine [ and the cohesion between inorganic and organic parts is due to hydrogen bonds.

  11. Experimental studies of the formation of cluster ions formed by corona discharge in an atmosphere containing SO2, NH3, and H2O

    Pedersen, J. O.; Hvelplund, P.; Støchkel, K.; Enghoff, M. B.; Kurten, T.


    We report on studies of ion induced nucleation in a corona discharge taking place in an atmosphere containing SO2, NH3, and H2O at standard temperature and pressure. Positive ions such as H3O+(H2O)n, NH4+(H2O)n, and H+(H2SO4)(H2O)n and negative ions such as HSO5-(H2O)n, SO4-(H2O)n, HSO4-(H2O)n and NO3-(H2O)n have been recorded. Large values of n (> 100) were observed and the experiment indicates the existence of even larger water clusters. In contrast, only clusters with a maximum of 2 sulfuric acid molecules were observed. Fragmentation studies also revealed that the negative ion HSO5-, which has been observed in many studies, in our experiments is contaminated by O2-(HNO3)(H2O) ions, and this may also have been the case in other experiments. Finally an ion with m/z = 232 (where m is the cluster mass in amu and z the charge state), capable of attaching H2O-molecules was observed and studied by fragmentation. Positive ion m/z (mass/charge) spectrum

  12. Surface desorption atmospheric pressure chemical ionization mass spectrometry for direct ambient sample analysis without toxic chemical contamination.

    Chen, Huanwen; Zheng, Jian; Zhang, Xie; Luo, Mingbiao; Wang, Zhichang; Qiao, Xiaolin


    Ambient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is used as a reagent to generate primary ions such as H(3)O(+), which is then directed to impact the sample surface for desorption and ionization. Under experimental conditions, protonated or deprotonated molecules of analytes present on various samples are observed using positive or negative corona discharge. Fast detection of trace amounts of analytes present in pharmaceutical preparations, viz foods, skins and clothes has been demonstrated without any sample pretreatment. Taking the advantage of the gasless setup, powder samples such as amino acids and mixtures of pharmaceutical preparations are rapidly analyzed. Impurities such as sudan dyes in tomato sauce are detected semiquantitatively. Molecular markers (e.g. putrescine) for meat spoilage are successfully identified from an artificially spoiled fish sample. Chemical warfare agent stimulants, explosives and herbicides are directly detected from the skin samples and clothing exposed to these compounds. This provides a detection limit of sub-pg (S/N > or = 3) range in MS2. Metabolites and consumed chemicals such as glucose are detected successfully from human skins. Conclusively, surface desorption atmospheric pressure chemical ionization (DAPCI) mass spectrometry, without toxic chemical contamination, detects various compounds in complex matrices, showing promising applications for analyses of human related samples.

  13. Experimental study of particle formation by ion-ion recombination

    Nagato, Kenkichi; Nakauchi, Masataka


    Particle formation by ion-ion recombination has been studied using an ion-ion recombination drift tube (IIR-DT). IIR-DT uses two DC corona ionizers to produce positive and negative ions at the ends of the drift tube. The ions of different polarity move in opposite directions along the electric field in the drift tube. We observed significant particle formation using ions generated in purified air containing H2O, SO2, and NH3. Particle formation was suppressed when no drift field was applied. We also observed few particles when we used a single discharge (positive or negative only). These results clearly show that particle formation observed in the IIR-DT was caused by nucleation by ion-ion recombination. Positive and negative ion species produced by corona ionizers were investigated using an atmospheric pressure ionization mass spectrometer. The ions involved in the particle formation were suggested to include H3O+(H2O)n and NH4+(H2O)n for positive ions and sulfur-based ions such as SO5-, SO5-NO2, and HSO4- for negative ions.


    Vasilii Gutsanu


    Full Text Available Using the Mossbauer spectroscopy and other physical methods it was demonstrated the presence of different iron compounds like β-FeOOH, α-Fe2O3, and jarosite mineral type compounds: (R4N,H3O[Fe3(OH6(SO42] or coordination modes: {RCOO-Fe(L4-OOCR}1+, {R-CO2=Fe(X2=O2C-R}n, {R-COO-Fe(X4-OOC-R}n, and {(-NCH2CH2N-= Fe(X2 =(-NCH2CH2N-}, where X= H2O, OH-, SO42-., n= from 3- to 1+ in the ion-exchange resins (KU-2, AN-31, AV-17, Varian – AD, EDE-10P after the contact with sulphate of iron(III solutions at different conditions: type of solvent, temperature, air atmosphere. In special conditions the ultrafine superparamagnetic particles of Fe2O3 have been obtained

  15. Characterization and nanomechanical properties of novel dental implant coatings containing copper decorated-carbon nanotubes.

    Sasani, N; Vahdati Khaki, J; Mojtaba Zebarjad, S


    Fluorapatite-titania coated Ti-based implants are promising for using in dental surgery for restoring teeth. One of the challenges in implantology is to achieve a bioactive coating with appropriate mechanical properties. In this research, simple sol-gel method was developed for synthesis of fluorapatite-titania-carbon nanotube decorated with antibacterial agent. Triethyl phosphate [PO4(C2H5)3], calcium nitrate [Ca(NO3)2] and ammonium fluoride (NH4F) were used as precursors under an ethanol-water based solution for fluorapatite (FA) production. Titanium isopropoxide and isopropanol were used as starting materials for making TiO2 sol-gels. Also, Copper acetate [Cu(C2H3O2)2·H2O] was used as precursor for decoration of multi walled carbon nanotubes (MWCNTs) with wet chemical method. The decorated MWCNTs (CNT(Cu)) were evaluated by transmission electron microscopy (TEM). The phase identification of the FA-TiO2-CNT(Cu) coating was carried out by XRD analysis. Morphology of coated samples was investigated by SEM observations. The surface elastic modulus and hardness of coatings were studied using nanoindentation technique. The results indicate that novel dental implant coating containing FA, TiO2 and copper decorated MWCNTs have proper morphological features. The results of nanoindentation test show that incorporation of CNT(Cu) in FA-TiO2 matrix can improve the nanomechanical properties of composite coating.

  16. Hydrides in Young Stellar Objects: Radiation tracers in a protostar-disk-outflow system

    Benz, Arnold O; van Dishoeck, Ewine F


    Context: Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays. Aims: We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation. Methods: W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration (about 2500 s) in 8 spectral regions. Results: The target lines including CH, NH, H3O+, and the new molecules SH+, H2O+, and OH+ are detected. The H2O+ and OH+ J=1-0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H2O+ and OH+ also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds. Conclusions: The molecular column densities derived from observations corre...

  17. Ion desorption from frozen H 2O irradiated by MeV heavy ions

    Collado, V. M.; Farenzena, L. S.; Ponciano, C. R.; Silveira, E. F. da; Wien, K.


    Nitrogen (0.13-0.85 MeV) and 252Cf fission fragments (˜65 MeV) beams are employed to sputter positive and negative secondary ions from frozen water. Desorption yields are measured for different ice temperatures and projectile energies. Target surface is continuously refreshed by condensed water while the target temperature varies and ice thickness changes. In both projectile energy ranges, the preferentially ejected ions are H +, H2+ and (H 2O) nH +-cluster ions. The yields of the corresponding negative ions H - and (H 2O) nO - or (H 2O) nOH - are 1-2 orders of magnitude lower. The (H 2O) nH + desorption yields decrease exponentially as the cluster size, n, increases. In the low energy range, the desorption of positive ion clusters may occur in a two-step process: first, desorption of preformed H 2O clusters and, then, ionization by H + or H 3O + capture. For 0.81 MeV N + projectile ions, the cluster ion emission contributes with 0.05% to the total H 2O desorbed yield. There are indications that emission of the (H 2O) nH + disappears for an electronic energy loss lower than 20 eV/Å. For the high energy range, desorption of small ion clusters is particularly enhanced, revealing that a fragmentation process also exists.

  18. Dye-sensitized solar cell characteristics of nanocomposite zinc ferrite working electrode: Effect of composite precursors and titania as a blocking layer on photovoltaic performance

    Habibi, Mohammad Hossein; Habibi, Amir Hossein; Zendehdel, Mahmoud; Habibi, Mehdi


    This research investigates the performance of a zinc ferrite (ZF) as working electrodes in a dye-sensitized solar cell (DSSC). This ZF working electrode was prepared by sol-gel and thermal decomposition of four different precursors including: zinc acetate dihydrate (Zn(CH3COO)2ṡ2H2O), ferric nitrate nonahydrate (Fe(NO3)3ṡ9H2O), iron(III) acetate; Fe(C2H3O2)3, and zinc nitrate hexahydrate, Zn(NO3)2ṡ6H2O. The effects of annealing temperature and precursors on the structural, morphological, and optical properties were investigated. The field emission scanning electron microscope images (FESEM) and scanning electron microscopy (SEM) show that ZFe films are polycrystalline in nature and homogeneous with densely packed grains. Nanoporous zinc ferrite coatings were prepared by doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in DSSC. In all DSSCs, platinized FTO and [Co(bpy)3]2+/3+ in 3-methoxy proponitrile were used as counter electrode and redox mediator system respectively. Comparing the fill factors of four different zinc ferrite nanocomposites, the highest fill factor was for ZnFe2O4-TBL sample. Cell fabricated with ZnFeA working electrode shows relatively higher Jsc.

  19. The composition of coexisting jarosite-group minerals and water from the Richmond mine, Iron Mountain, California

    Jamieson, H.E.; Robinson, C.; Alpers, C.N.; Nordstrom, D.K.; Poustovetov, A.; Lowers, H.A.


    Jarosite-group minerals accumulate in the form of stalactites and fine-grained mud on massive pyrite in the D drift of the Richmond mine, Iron Mountain, California. Water samples were collected by placing beakers under the dripping stalactites and by extracting pore water from the mud using a centrifuge. The water is rich in Fe3+ and SO42-, with a pH of approximately 2.1, which is significantly higher than the extremely acidic waters found elsewhere in the mine. Electron-microprobe analysis and X-ray mapping indicate that the small crystals (<10 ??m in diameter) are compositionally zoned with respect to Na and K, and include hydronium jarosite corresponding to the formula (H3O)0.6K0.3 Na0.1Fe3+3 (SO4)2(OH)6. The proton-microprobe analyses indicate that the jarosite-group minerals contain significant amounts of As, Pb and Zn, and minor levels of Bi, Rb, Sb, Se, Sn and Sr. Speciation modeling indicates that the drip waters are supersaturated with respect to jarosite-group minerals. The expected range in composition of jarosite-group solid-solution in equilibrium with the pore water extracted from the mud was found to be consistent with the observed range in composition.

  20. High-resolution structure of the rotor ring of a proton-dependent ATP synthase.

    Pogoryelov, Denys; Yildiz, Ozkan; Faraldo-Gómez, José D; Meier, Thomas


    The crystal structure of the c-ring from the proton-coupled F1Fo ATP synthase from Spirulina platensis is shown at 2.1-A resolution. The ring includes 15 membrane-embedded c subunits forming an hourglass-shaped assembly. The structure demonstrates that proton translocation across the membrane entails protonation of a conserved glutamate located near the membrane center in the c subunit outer helix. The proton is locked in this site by a precise hydrogen bond network reminiscent of that in Na+-dependent ATP synthases. However, the structure suggests that the different coordination chemistry of the bound proton and the smaller curvature of the outer helix drastically enhance the selectivity of the H+ site against other cations, including H3O+. We propose a model for proton translocation whereby the c subunits remain in this proton-locked state when facing the membrane lipid. Proton exchange would occur in a more hydrophilic and electrostatically distinct environment upon contact with the a subunit interface.

  1. Structural, physicochemical characterization and antimicrobial activities of a new Tetraaqua bismaleato Iron(II) complex

    Badiaa Essghaier; Jawher Abdelhak; Amani Naouar; Nourchene Toukebri; Mohamed Faouzi Zid; Najla Sadfi-Zouaoui


    Tetraaqua bismaleato iron(II) [Fe(C4H3O4)2 (H2O)4], (1) is a new synthetic antimicrobial agent. Thermal analysis shows that the dehydration of the compound occurs in agreement with the structure. The single crystal salt crystallizes in the triclinic space group -1 with = 5.171(2) Å, = 7.309(3) Å, = 9.731(3) Å, = 109.15(2)°, = 115.02(2)°, = 92.42(1)°, = 313.6(3) Å3 and Z = 1. Three dimensional network is formed by strong intermolecular O – H . . . O hydrogen bonds. Magnetic susceptibility measurements of 1 in the range 2–300 K exhibited paramagnetic behavior at high temperature. However, at low temperature, the susceptibility data showed weak antiferromagnetic interactions between the local spins. Antimicrobial activity of 1 was tested. It showed high response against gram-positive and gram-negative bacteria as well as fungi and the MIC and IC50 values ranged from 8 to 256 g.mL−1 and from 1.38 to 22.19 g.mL−1, respectively.

  2. Studies on the Behavior and Mechanisms of Ivermectin in Electrospray Ionization Mass Spectrometry%伊维菌素在电喷雾质谱中的行为及其机理的研究

    吴增茹; 朱丽荔; 骆宏鹏; 徐筱杰



  3. Water Complexes Take Part in Biological Effect Created by Weak Combined Magnetic Field

    Sheykina, Nadiia


    It was revealed experimentally that at small level of magnetic field's noise (less than 4µT/Hz0.5) the dependence of gravitropc reaction of cress roots on frequency had a fine structure/ The peak that corresponded to the cyclotron frequency of Ca2+ ions for the static component of combined magnetic field that was equal to 40µT became split up into three peaks ( f1 = 31/3Hz, f2 = 32.5Hz i f3 = 34 Hz./ . The frequency f1 corresponded to the Ca2+ ion (theoretical value 31.6 Hz), the frequency f2 corresponded to the hydronium ion H3O+ (theoretical value 32.9 Hz), the frequency f3 corresponded to OH- ion (theoretical value 35 Hz). Taking into account the influence of combined magnetic field on hydronium ions and Del Giudice' hypothesis one may throw away doubts about the possibility of ion cyclotron resonance. The hydronium ions are unusual because they have a long free path length. It was revealed that pH of the distillated water changed under the treatment in combined magnetic field tuned to cyclotron frequency of hydronium ion. Such changes in pH had to lead to the biological effects on the molecular ,cell and organism levels.

  4. [{Cu(phen)2}(mu-malato){Cu(phen)(NO3)}](NO3).4H2O: malate acting as a tetradentate and dibridging ligand in a dinuclear copper complex.

    Zhang, Xiang Dong; Sun, Jin Yu; Zhao, Zhen; Ma, Yong Chao; Zhu, Miao Li


    The crystal structure of the title compound, mu-2-hydroxybutanedioato-1kappa2O4,O4':2kappa3O1,O2,O4-nitrato-2kappaO-tris(1,10-phenanthroline)-1kappa(4)N,N';2kappa(2)N,N'-dicopper(II) nitrate tetrahydrate, [Cu2(C4H3O5)(NO3)(C12H8N2)3](NO3).4H2O, contains an unsymmetrical dinuclear copper complex with Cu(phen)2 and Cu(phen)(NO3) moieties (phen is 1,10-phenanthroline) bridged by a malate (2-hydroxybutanedioate) ligand, which acts as a double-bridging and tetradentate ligand. As a result of this double-bridging action, especially the direct coordination of the O atom of one carboxylate group of malate to the two Cu atoms, the Cu...Cu distance is only 4.199 (1) Angstrom and the two phen planes are roughly parallel [the shortest interplanar distance is 3.28 (1) Angstrom], exhibiting an obvious intramolecular pi-pi stacking interaction.

  5. Emissions of Volatile Organic Compounds (VOCs) from Animal Husbandry: Chemical Compositions, Separation of Sources and Animal Types

    Yuan, B.; Coggon, M.; Koss, A.; Warneke, C.; Eilerman, S. J.; Neuman, J. A.; Peischl, J.; Aikin, K. C.; Ryerson, T. B.; De Gouw, J. A.


    Concentrated animal feeding operations (CAFOs) are important sources of volatile organic compounds (VOCs) in the atmosphere. We used a hydronium ion time-of-flight chemical ionization mass spectrometer (H3O+ ToF-CIMS) to measure VOC emissions from CAFOs in the Northern Front Range of Colorado during an aircraft campaign (SONGNEX) for regional contributions and from a mobile laboratory sampling for chemical characterizations of individual animal feedlots. The main VOCs emitted from CAFOs include carboxylic acids, alcohols, carbonyls, phenolic species, sulfur- and nitrogen-containing species. Alcohols and carboxylic acids dominate VOC concentrations. Sulfur-containing and phenolic species become more important in terms of odor activity values and NO3 reactivity, respectively. The high time-resolution mobile measurements allow the separation of the sources of VOCs from different parts of the operations occurring within the facilities. We show that the increase of ethanol concentrations were primarily associated with feed storage and handling. We apply a multivariate regression analysis using NH3 and ethanol as tracers to attribute the relative importance of animal-related emissions (animal exhalation and waste) and feed-related emissions (feed storage and handling) for different VOC species. Feed storage and handling contribute significantly to emissions of alcohols, carbonyls and carboxylic acids. Phenolic species and nitrogen-containing species are predominantly associated with animals and their waste. VOC ratios can be potentially used as indicators for the separation of emissions from dairy and beef cattle from the regional aircraft measurements.

  6. Carborane acids. New "strong yet gentle" acids for organic and inorganic chemistry.

    Reed, Christopher A


    Icosahedral carborane anions such as CHB11Cl11- are amongst the least coordinating, most chemically inert anions known. They are also amongst the least basic, so their conjugate acids, H(carborane), are superacids (i.e. stronger than 100% H2SO4). Acidity scale measurements indicate that H(CHB11Cl11) is the strongest pure Brønsted acid presently known, surpassing triflic and fluorosulfuric acid. Nevertheless, it is also an extremely gentle acid--because its conjugate base engages in so little chemistry. Carborane acids separate protic acidity from anion nucleophilicity and destructive oxidative capacity in the conjugate base, to a degree not previously achieved. As a result, many long-sought, highly acidic, reactive cations such as protonated benzene (C6H7+), protonated C60(HC60+), tertiary carbocations (R3C+), vinyl cations (R2C=C(+)-R), silylium ions (R3Si+) and discrete hydronium ions (H3O+, H5O2+ etc.) can be readily isolated as carborane salts and characterized at room temperature by X-ray crystallography.

  7. Switchable Ionic Liquids: An Environmentally Friendly Medium to Synthesise Nanoparticulate Green Rust

    Lao, David; Kukkadapu, Ravi; Kovarik, Libor; Arey, Bruce; Heldebrant, David; Nune, Satish


    Under anoxic conditions, a novel nanoparticulate green rust with carbonate (nano GR) was synthesized by addition of methanol to degassed switchable ionic liquid (SWIL) solution comprised of 1-hexanol, diazabicycloundec-7-ene (DBU), CO2 and Fe(C2H3O2)2 (Fe(OAc)2). Variable temperature Mössbauer spectroscopy studies indicated the product to be predominantly GR while TEM-SAED method confirmed it be nanoparticulate in nature. Experiments with and without methanol in the SWIL medium suggest that methanol may be responsible for Fe(II) oxidation to Fe(III) necessary for GR formation. Studies with Ar instead of CO2 trigger gas indicated that CO2 is essential for GR formation. Conditions to generate CO32- anion was most likely provided by basic environment of the medium. The nano GR suspension was very reactive and instantaneously oxidized completely to a reddish-brown precipitate upon exposure to ambient atmosphere. The nature of the oxidized sample is not certain. The oxidized product, however, appears to be a mix of ferric green rust- [GR(CO32-]*; major] and ferrihydrite-like minerals. To our knowledge, this is first report of use of environmentally-friendly SWIL reagents to synthesize very reactive nano GR materials.

  8. Use of a least absolute shrinkage and selection operator (LASSO) model to selected ion flow tube mass spectrometry (SIFT-MS) analysis of exhaled breath to predict the efficacy of dialysis: a pilot study.

    Wang, Maggie Haitian; Chong, Ka Chun; Storer, Malina; Pickering, John W; Endre, Zoltan H; Lau, Steven Yf; Kwok, Chloe; Lai, Maria; Chung, Hau Yin; Ying Zee, Benny Chung


    Selected ion flow tube-mass spectrometry (SIFT-MS) provides rapid, non-invasive measurements of a full-mass scan of volatile compounds in exhaled breath. Although various studies have suggested that breath metabolites may be indicators of human disease status, many of these studies have included few breath samples and large numbers of compounds, limiting their power to detect significant metabolites. This study employed a least absolute shrinkage and selective operator (LASSO) approach to SIFT-MS data of breath samples to preliminarily evaluate the ability of exhaled breath findings to monitor the efficacy of dialysis in hemodialysis patients. A process of model building and validation showed that blood creatinine and urea concentrations could be accurately predicted by LASSO-selected masses. Using various precursors, the LASSO models were able to predict creatinine and urea concentrations with high adjusted R-square (>80%) values. The correlation between actual concentrations and concentrations predicted by the LASSO model (using precursor H3O(+)) was high (Pearson correlation coefficient  =  0.96). Moreover, use of full mass scan data provided a better prediction than compounds from selected ion mode. These findings warrant further investigations in larger patient cohorts. By employing a more powerful statistical approach to predict disease outcomes, breath analysis using SIFT-MS technology could be applicable in future to daily medical diagnoses.

  9. Detecting volatile compounds from Kraft lignin degradation in the headspace of microbial cultures by selected ion flow tube mass spectrometry (SIFT-MS).

    Gibson, Andrew; Malek, Lada; Dekker, Robert F H; Ross, Brian


    Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) was used to quantify methanol and other volatile compounds in the headspace of one bacterial and 12 fungal lignin-degrading microbial cultures. Cultures were grown in 250 mL Erlenmeyer flasks capped with aluminum foil containing 40 mL of nutrient media using Kraft lignin (0.3% w/v) as the sole carbon source. Analysis was done using SIFT-MS with H3O(+) and NO(+) precursors. Product ions were identified with multiple ion mode (MIM). Full scan (FS) mode was used to identify other compounds of interest. Absidia cylindrospora, Ischnoderma resinosum and Pholiota aurivella increased headspace methanol concentration by 136 ppb, 1196 ppb and 278 ppb, respectively, while Flammulina velutipes and Laetiporus sulphureus decreased concentration below ambient levels. F. velutipes and L. sulphureus were found to produce products of methanol oxidation (formaldehyde and formic acid) and were likely metabolizing methanol. Some additional unidentified compounds generated by the fungal cultures are intriguing and will require further study. SIFT-MS can be used to quantify methanol and other volatile compounds in the headspace of microbial cultures and has the potential to be a rapid, sensitive, non-invasive tool useful in elucidating the mechanisms of lignin degradative pathways.

  10. A New One-dimensional Chain Compound Constructed by {Mo8O28} units via Corner-sharing

    余雅琴; 杨文斌; 吴传德; 卢灿忠


    The title compound, {(H3O)4(NH4)4[Mo8O28]·2H2O}n 1, has been synthesized rature, and its crystal structure was determined by X-ray single-crystal analysis with the following crystallographic data: monoclinic system, space group P21/n, a = 9.5234(6), b = 11.3235(8), c = 14.8812(10) (A), β = 107.467(2)°, V= 1530.77(18) (A)3, Z= 4, F(000) = 1336,μ = 3.293 mm-1 and Dc= 3.037 g/cm3. The final R = 0.0619 for 2691 observed reflections (I > 2σ(I)). X-ray crys tal structure analysis showed that the novel one-dimensional chain compound is built up by basic { Mo8O28 } units via singleμ2-O, and such chains are further linked into a three-dimensional net work by hydrogen bonds.

  11. Reactions of Laser Ablated Metal Plasma with Molecular Alcohol Beams: Dependence of the Produced Cluster Ion Species on the Beam Condition

    NIU Dong-Mei; LI Hai-Yang; ZHANG Shu-Dong


    The gas phase reactions of metal plasma with alcohol clusters were studied by time of flight mass spectrometry(TOFMS) using laser ablation-molecular beam (LAMB) method. The significant dependence of the product cluster ions on the molecular beam conditions was observed. When the plasma acted on the low density parts of the pulsed molecular beam, the metal-alcohol complexes M+An (M=Cu, Al, Mg, Ni and A=C2H5OH, CH3OH) were the dominant products, and the sizes of product ion clusters were smaller. While the plasma acted on the high density part of the beam, however, the main products turned to be protonated alcohol clusters H+An and, as the reactions of plasma with methanol were concerned, the protonated water-methanol complexes H3O+(CH3OH)n with a larger size(n≤ 12 for ethanol and n≤24 for methanol). Similarly, as the pressure of the carrier helium gas was varied from1 × 105 to 5 × 105 Pa, the main products were changed from M+An to H+An and the sizes of the clusters also increased. The changes in the product clusters were attributed to the different formation mechanism of the output ions,that is, the M+An ions came from the reaction of metal ion with alcohol clusters, while H+An mainly from collisional reaction of electron with alcohol clusters.

  12. Model-Observation Comparisons of Electron Number Densities in the Coma of 67P/Churyumov-Gerasimenko during January 2015

    Vigren, E.; Altwegg, K.; Edberg, N. J. T.; Eriksson, A. I.; Galand, M.; Henri, P.; Johansson, F.; Odelstad, E.; Tzou, C.-Y.; Valliéres, X.


    During 2015 January 9-11, at a heliocentric distance of ˜2.58-2.57 au, the ESA Rosetta spacecraft resided at a cometocentric distance of ˜28 km from the nucleus of comet 67P/Churyumov-Gerasimenko, sweeping the terminator at northern latitudes of 43°N-58°N. Measurements by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Comet Pressure Sensor (ROSINA/COPS) provided neutral number densities. We have computed modeled electron number densities using the neutral number densities as input into a Field Free Chemistry Free model, assuming H2O dominance and ion-electron pair formation by photoionization only. A good agreement (typically within 25%) is found between the modeled electron number densities and those observed from measurements by the Mutual Impedance Probe (RPC/MIP) and the Langmuir Probe (RPC/LAP), both being subsystems of the Rosetta Plasma Consortium. This indicates that ions along the nucleus-spacecraft line were strongly coupled to the neutrals, moving radially outward with about the same speed. Such a statement, we propose, can be further tested by observations of H3O+/H2O+ number density ratios and associated comparisons with model results.

  13. Amine-templated one-dimensional metal sulfates including a mixed-valent Fe compound with a half-kagome structure.

    Behera, J N; Rao, C N R


    Organically templated metal sulfates are relatively new. Six amine-templated transition-metal sulfates with different types of chain structures, including a novel iron sulfate with a chain structure corresponding to one half of the kagome structure, were synthesized by hydro/solvothermal methods. Amongst the one-dimensional metal sulfates, [C10N2H10][Zn(SO4)Cl2] (1) is the simplest, being formed by corner-linked ZnO2Cl2 and SO4 tetrahedra. [C6N2H18][Mn(SO4)2(H2O)2] (2) and [C2N2H10][Ni(SO4)2(H2O)2] (3) have ladder structures comprising four-membered rings formed by SO4 tetrahedra and metal-oxygen octahedra, just as in the mineral kröhnkite. [C4N2H12][V(III)(OH)(SO4)2]H2O (4) and [C4N2H12][VF3(SO4)] (5) exhibit chain topologies of the minerals tancoite and butlerite, respectively. The structure of [C4N2H12][H3O][Fe(III)Fe(II) F6(SO4)] (6) is noteworthy in that it corresponds to half of the hexagonal kagome structure. It exhibits ferrimagnetic properties at low temperatures and the absence of frustration, unlike the mixed-valent iron sulfate with the full kagome structure.

  14. Solvent effects on the photochemistry of 4-aminoimidazole-5-carbonitrile, a prebiotically plausible precursor of purines.

    Szabla, Rafał; Sponer, Judit E; Sponer, Jiří; Sobolewski, Andrzej L; Góra, Robert W


    4-Aminoimidazole-5-carbonitrile (AICN) was suggested as a prebiotically plausible precursor of purine nucleobases and nucleotides. Although it can be formed in a sequence of photoreactions, AICN is immune to further irradiation with UV-light. We present state-of-the-art multi-reference quantum-chemical calculations of potential energy surface cuts and conical intersection optimizations to explain the molecular mechanisms underlying the photostability of this compound. We have identified the N-H bond stretching and ring-puckering mechanisms that should be responsible for the photochemistry of AICN in the gas phase. We have further considered the photochemistry of AICN-water clusters, while including up to six explicit water molecules. The calculations reveal charge transfer to solvent followed by formation of an H3O(+) cation, both of which occur on the (1)πσ* hypersurface. Interestingly, a second proton transfer to an adjacent water molecule leads to a (1)πσ*/S0 conical intersection. We suggest that this electron-driven proton relay might be characteristic of low-lying (1)πσ* states in chromophore-water clusters. Owing to its nature, this mechanism might also be responsible for the photostability of analogous organic molecules in bulk water.

  15. Di-μ2-acetato-1:2κ2O:O′;2:3κ2O:O′-bis(N,N′-dimethylformamide-1κO,3κO-bis{μ2-2,2′-[propane-1,3-diylbis(iminomethylene]diphenolato-1κ4O,N,N′,O′:2κ2O,O′;2κ2O,O′:3κ4O,N,N′,O′-1,3-dinickel(II-2-cadmium(II

    Orhan Atakol


    Full Text Available The crystal structure of the title compound, [Ni2Cd(C17H16N2O22(C2H3O22(C3H7NO2], contains discrete centrosymmetric hetero-trinuclear molecules in which Ni/Cd atom pairs are triply bridged via O atoms from the SALPD2− [N,N′-bis(salicylidene-1,3-propanediaminate] and acetate ligands. The central CdII ion is in a distorted octahedral coordination environment formed by four O atoms from two SALPD2− ligands in the equatorial plane and two O atoms of two symmetry-related acetate ligands in the axial positions. The symmetry-related NiII ions are in slightly distorted octahedral environments, coordinated by two O and two N atoms from tetradendate SALPD2− ligands in the equatorial plane, while the axial positions are occupied by O atoms from a dimethylformamide and an acetate ligand. This results in the formation of three edge-shared octahedra in which the Ni...Cd distance is 3.1482 (15 Å. The crystal structure is stabilized by weak C—H...O hydrogen bonds.

  16. N-dimensional switch function for energy conservation in multiprocess reaction dynamics.

    Mogo, César; Brandão, João


    The MReaDy program was designed for studying Multiprocess Reactive Dynamic systems, that is, complex chemical systems involving different and concurrent reactions. It builds a global potential energy surface integrating a variety of potential energy surfaces, each one of them representing an elementary reaction expected to play a role in the chemical process. For each elementary reaction, energy continuity problems may happen in the transition between potential energy surfaces due to differences in the functional form for each of the fragments, especially if built by different authors. A N-dimensional switch function is introduced in MReaDy in order to overcome such a problem. As an example, results of a collision trajectory calculation for H2  + OH → H3 O are presented, showing smooth transition in the potential energy, leading to conservation in the total energy. Calculations for a hydrogen combustion system from 1000 K up to 4000 K shows a variation of 0.012% when compared to the total energy of the system. © 2016 Wiley Periodicals, Inc.

  17. Potencialidades do dióxido de chumbo eletrodepositado como sensor potenciométrico Potentialities of electrodeposited lead dioxide as a potentiometric sensor

    Milton Duffles Capelato


    Full Text Available This paper proposes an experiment to be performed in both instrumental analysis and experimental physical-chemistry curricular disciplines in order to open options to develop challenging basic research activities. Thus the experimental procedures and the results obtained in the preparation of electrodeposited lead dioxide onto graphite and its evaluation as potentiometric sensor for H3O+ and Pb2+ ions, are presented. The data obtained in acid-base titrations were compared with those of the traditional combination glass electrode at the same conditions. Although a linear sub-Nernstian response to free hydrogen ions was observed for the electrodeposited PbO2 electrode, a good agreement was obtained between them. Working as lead(II sensing electrode, the PbO2 showed a linear sub-Nernstian behavior at total Pb2+ concentrations ranging from 3,5 x 10-4 to 3,0 x 10-2 mol/L in nitrate media. For the redox couple PbO2/Pb(II the operational slope converges to the theoretical one, as the acidity of the working solution increases.

  18. A new lithium salt with 3-fluoro-1,2-benzenediolato and lithium tetrafluoroborate for lithium battery electrolytes

    Xue, Zhao-Ming; Zhao, Ben-Hao; Chen, Chun-Hua


    A new unsymmetrical lithium salt containing F-, C6H3O2F2- [dianion of 3-fluoro-1,2-benzenediol], lithium difluoro(3-fluoro-1,2-benzene-diolato(2-)-o,o‧)borate (FLDFBDB) is synthesized and characterized. The thermal characteristics of it, and its derivatives, lithium bis[3-fluoro-1, 2-benzenediolato(2-)-o,o]borate (FLBBB), and lithium fluoroborate (LiBF4) are examined by thermogravimetric analysis (TG). The thermal decomposition in air begins at 256 °C, 185 °C, and 162 °C for FLBBB, FLDFBDB and LiBF4, respectively. The order of the stability toward the oxidation of these organoborates is LiBF4 > FLDFBDB > FLBBB. The cyclic voltammetry study shows that the FLDFBDB solution in propylene carbonate (PC) is stable up to 3.9 V vs. Li+/Li. It is soluble in common organic solvents. Ionic dissociation properties of FLDFBDB and its derivatives are examined by conductivity measurements in PC, PC + ethyl methyl carbonate (EMC), PC + dimethyl ether (DME), PC + ethylene carbonate (EC) + DME, PC + EC + EMC solutions. The conductivity values of the 0.10 mol dm-3 FLDFBDB electrolyte in these solutions are higher than those of FLBBB, but lower than those of LiBF4 electrolytes.

  19. Effects of Ambient Humidity on Plant Growth Enhancement by Atmospheric Air Plasma Irradiation to Plant Seeds

    Sarinont, Thapanut; Amano, Takaaki; Koga, Kazunori; Shiratani, Masaharu


    Humidity is an important factor for plasma-bio applications because composition of species generated by atmospheric pressure plasmas significantly depends on the humidity. Here we have examined effects of humidity on the growth enhancement to study the mechanism. Experiments were carried out with a scalable DBD device. 10 seeds of Raphanus sativus L. were set for x = 5 mm and y = 3 mm below the electrodes. The humidity Hair was 10 - 90 %Rh. The ratio of length of plants with plasma irradiation to that of control increases from 1.2 for Hair = 10 %Rh to 2.5 for Hair = 50 %Rh. The ratio is 2.5 for Hair = 50-90 %Rh. This humidity dependence is similar to the humidity dependence of O2+-H2O,H3O*, NO2--H2Oand NO3--H2Odensities, whereas it is different from that of other species such as O3, NO, and so on. The similarity gives information on key species for the growth enhancement.

  20. An application of the novel quantum mechanical/molecular mechanical method combined with the theory of energy representation: An ionic dissociation of a water molecule in the supercritical water.

    Takahashi, Hideaki; Satou, Wataru; Hori, Takumi; Nitta, Tomoshige


    A novel quantum chemical approach recently developed has been applied to an ionic dissociation of a water molecule (2H(2)O-->H(3)O(+)+OH(-)) in ambient and supercritical water. The method is based on the quantum mechanical/molecular mechanical (QM/MM) simulations combined with the theory of energy representation (QM/MM-ER), where the energy distribution function of MM solvent molecules around a QM solute serves as a fundamental variable to determine the hydration free energy of the solute according to the rigorous framework of the theory of energy representation. The density dependence of the dissociation free energy in the supercritical water has been investigated for the density range from 0.1 to 0.6 g/cm(3) with the temperature fixed at a constant. It has been found that the product ionic species significantly stabilizes in the high density region as compared with the low density. Consequently, the dissociation free energy decreases monotonically as the density increases. The decomposition of the hydration free energy has revealed that the entropic term (-TDeltaS) strongly depends on the density of the solution and dominates the behavior of the dissociation free energy with respect to the variation of the density. The increase in the entropic term in the low density region can be attributed to the decrease in the translational degrees of freedom brought about by the aggregation of solvent water molecules around the ionic solute.

  1. Determination of pectin methylesterase activity in commercial pectinases and study of the inactivation kinetics through two potentiometric procedures

    Samantha Lemke Gonzalez


    Full Text Available Pectinases are enzymes that degrade pectic substances and are widely used in juice and fruit beverages to improve the quality of the process. The objective of this study was to determine the optimum pH and temperature of two samples of commercial pectinases and propose an alternative procedure to determine the residual activity comparing the data with those of the traditional procedure. The pectin methylesterase (PME activity in Pectinex 100 L Plus and Panzyn Clears was determined by potentiometry. The reaction consisted of 5.00 mg.mL-1 apple pectin, 0.100 mol.L-1 NaCl, and 50 µL enzyme to a total volume of 30 mL. The pectin reaction in the presence of PME in all experiments revealed a first order kinetics. The PME in the two enzyme preparations showed higher activity at pH 4.0 to 4.5 and temperature of 45 ºC. From the results of both procedures ΔV NaOH/Δt and ΔpH/Δt, it was concluded that the inactivation of PME occurred at 75 ºC. The results obtained from the ratio ΔpH/Δt showed good correlation with those obtained from the ratio ΔV NaOH/Δt. In the reaction accompanied by the ratio ΔpH/Δt, the release of H3O+ occurred in the real time reaction.

  2. Synthesis of transparent aqueous sols of colloidal layered niobate nanocrystals at room temperature.

    Ban, Takayuki; Yoshikawa, Shogo; Ohya, Yutaka


    Transparent aqueous sols of colloidal tetramethylammonium niobate nanocrystals were synthesized by mixing tetramethylammonium hydroxide (TMAOH), niobium ethoxide, and water at TMAOH/Nb≥0.7 at room temperature. The X-ray diffraction patterns of the thin films prepared by evaporating the colloidal solutions on a glass substrate indicated that the colloidal niobate had a layered crystalline structure. Two types of layered structures are known as a layered niobate, i.e. M(4)Nb(6)O(17)·nH(2)O and MNb(3)O(8) (M=H, H(3)O, or alkaline metal). Raman spectra and electron diffraction suggested that the niobate nanocrystals were similar in crystal structure to M(4)Nb(6)O(17)·nH(2)O compounds. Moreover, when niobium oxide thin films were fabricated from the niobate colloidal solutions by the sol-gel method, oriented T-Nb(2)O(5) thin films, whose c-axis was parallel to the substrate surface, were obtained. The orientation of the thin films was probably attributed to the layered structure of the colloidal niobate nanocrystals. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. A limited anodic and cathodic potential window of MoS2: limitations in electrochemical applications.

    Nasir, Muhammad Zafir Mohamad; Sofer, Zdenek; Ambrosi, Adriano; Pumera, Martin


    Molybdenum disulphide has been touted as a good material with diverse possible applications such as an energy storage and sensing platform. However, we demonstrate here the limitation of MoS2 as an analytical sensing platform due to the limited potential window in both the anodic and cathodic regions attributed to the inherent electrochemistry (oxidation of Mo(4+) to Mo(6+)) and the catalytic hydrogen evolution reaction due to H3O(+) reduction on the MoS2 surface, respectively. The electrochemical window of MoS2 lies in the region of ∼-0.6 V to +0.7 V (vs. AgCl). We show that such a limited working potential window characteristic of MoS2 precludes the detection of important analytes such as nitroaromatic explosives, pesticides and mycotoxins which are instead detectable on carbon surfaces. The limited potential window of MoS2 has to be taken into consideration in the construction of electroanalytical devices based on MoS2.

  4. On the origin of the ionosphere at Moon : a study using results from Chandrayaan-I S-band radio occultation experiment and a photochemical model

    Kailasam Madathil, Ambili; Bhardwaj, Anil; Choudhary, Raj Kumar


    Using Chandrayaan-1 communication link between orbiter and ground (S-band frequency), the presence of ionosphere at Moon has been explored using Radio Occultation technique. Results obtained from the observations conducted between July 30 and August 14, 2009 show evidence for a possible existence of the Ionosphere at Moon. A few seconds before the occultation of Chandrayaan-1 radio signals, extra fluctuation in the rate of change of difference between the theoretically estimated Doppler and observed Doppler was observed. The fluctuation was more pronounced when the probing radio waves were crossing through the day-night terminator. Using standard onion-peeling technique to invert the phase changes in radio signals to the refractivity of the medium, we estimated the bending angle and hence the electron density profiles for the Lunar medium. The estimated electron density near the Lunar surface was of the order of 400 - 1000 cm ^{-3} which decreased monotonically with increasing altitude till about 40 km above the surface where it became negligible. The observed electron density was compared with the results from a model which was developed based on CHACE measurements abroad Moon Impact Probe of Chandrayaan-I. The model included the photo chemical reactions and solar wind interactions of the lunar plasma. We propose that the ionosphere over Moon could have molecular origin with H _{2}O ^{+},CO_{2} ^{+} and H_{3}O ^{+} as dominant ions.

  5. Chemical Features in the Circumnuclear Disk of the Galactic Center

    Harada, N; Viti, S; Jiménez-Serra, I; Requena-Torres, M A; Menten, K M; Martín, S; Aladro, R; Martin-Pintado, J; Hochgürtel, S


    The circumnuclear disk (CND) of the Galactic Center is exposed to many energetic phenomena coming from the supermassive black hole Sgr A* and stellar activities. These energetic activities can affect the chemical composition in the CND by the interaction with UV-photons, cosmic-rays, X-rays, and shock waves. We aim to constrain the physical conditions present in the CND by chemical modeling of observed molecular species detected towards it. We analyzed a selected set of molecular line data taken toward a position in the southwest lobe of the CND with the IRAM 30m and APEX 12-meter telescopes and derived the column density of each molecule using a large velocity gradient (LVG) analysis. The determined chemical composition is compared with a time-dependent gas-grain chemical model based on the UCL\\_CHEM code that includes the effects of shock waves with varying physical parameters. Molecules such as CO, HCN, HCO$^+$, HNC, CS, SO, SiO, NO, CN, H$_2$CO, HC$_3$N, N$_2$H$^+$ and H$_3$O$^+$ are detected and their co...

  6. Molecules in the Circumnuclear Disk of the Galactic Center

    Harada, Nanase; Viti, Serena; Menten, Karl; Requena-Torres, Miguel; Guesten, Rolf; Hochguertel, Stefan


    Within a few parsecs around the central Black Hole Sgr A*, chemistry in the dense molecular cloud material of the circumnuclear disk (CND) can be affected by many energetic phenomena such as high UV-flux from the massive central star cluster, X-rays from Sgr A*, shock waves, and an enhanced cosmic-ray flux. Recently, spectroscopic surveys with the IRAM 30 meter and the APEX 12 meter telescopes of substantial parts of the 80--500 GHz frequency range were made toward selected positions in and near the CND. These datasets contain lines from the molecules HCN, HCO$^+$, HNC, CS, SO, SiO, CN, H$_2$CO, HC$_3$N, N$_2$H$^+$, H$_3$O$^+$ and others. We conduct Large Velocity Gradient analyses to obtain column densities and total hydrogen densities, $n$, for each species in molecular clouds located in the southwest lobe of CND. The data for the above mentioned molecules indicate 10$^5\\,$cm$^{-3} \\lesssim n <10^6\\,$cm$^{-3}$, which shows that the CND is tidally unstable. The derived chemical composition is compared wit...

  7. Crystal structure of a compact three-dimensional metal-organic framework based on Cs(+) and (4,5-di-cyano-1,2-phenyl-ene)bis-(phospho-nic acid).

    Mendes, Ricardo F; Venkatramaiah, Nutalapati; Tomé, João P C; Almeida Paz, Filipe A


    A new metal-organic framework compound, poly[[μ7-dihydrogen (4,5-di-cyano-1,2-phenyl-ene)diphospho-nato]-(oxonium)caesium], [Cs(C8H4N2O6P2)(H3O)] n (I), based on Cs(+) and the organic linker 4,5-di-cyano-1,2-phenyl-ene)bis-(phospho-nic acid, (H4cpp), containing two distinct coordinating functional groups, has been prepared by a simple diffusion method and its crystal structure is reported. The coordination polymeric structure is based on a CsO8N2 complex unit comprising a monodentate hydro-nium cation, seven O-atom donors from two phospho-nium groups of the (H2cpp)(2-) ligand, and two N-atom donors from bridging cyano groups. The high level of connectivity from both the metal cation and the organic linker allow the formation of a compact and dense three-dimensional network without any crystallization solvent. Topologically (I) is a seven-connected uninodal network with an overall Schäfli symbol of {4(17).6(4)}. Metal cations form an undulating inorganic layer, which is linked by strong and highly directional O-H⋯O hydrogen-bonding inter-actions. These metallic layers are, in turn, connected by the organic ligands along the [010] direction to form the overall three-dimensional framework structure.

  8. Crystal structure of poly[di-aqua-(μ-2-carb-oxy-acetato-κ(3) O,O':O'')(2-carb-oxy-acetato-κO)di-μ-chlorido-dicobalt(II)].

    Bouaoud, Yasmina; Setifi, Zouaoui; Buvailo, Andrii; Potaskalov, Vadim A; Merazig, Hocine; Dénés, Georges


    The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2] n , comprises one Co(II) atom, one water mol-ecule, one singly deprotonated malonic acid mol-ecule (HMal(-); systematic name 2-carb-oxy-acetate) and one Cl(-) anion. The Co(II) atom is octa-hedrally coordinated by the O atom of a water mol-ecule, by one terminally bound carboxyl-ate O atom of an HMal(-) anion and by two O atoms of a chelating HMal(-) anion, as well as by two Cl(-) anions. The Cl(-) anions bridge two Co(II) atoms, forming a centrosymmetric Co2Cl2 core. Each malonate ligand is involved in the formation of six-membered chelate rings involving one Co(II) atom of the dinuclear unit and at the same time is coordinating to another Co(II) atom of a neighbouring dinuclear unit in a bridging mode. The combination of chelating and bridging coordination modes leads to the formation of a two-dimensional coordination polymer extending parallel to (001). Within a layer, O-Hwater⋯Cl and O-Hwater⋯O hydrogen bonds are present. Adjacent layers are linked through O-H⋯O=C hydrogen bonds involving the carb-oxy-lic acid OH and carbonyl groups.

  9. Neutral and Ionized Hydrides in Star-forming Regions -- Observations with Herschel/HIFI

    Benz, Arnold O; van Dishoeck, Ewine F; Staeuber, Pascal; Wampfler, Susanne F


    The cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines of OH, CH, NH, SH and their ions OH+, CH+, NH+, SH+, H2O+, and H3O+ were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory. Molecular column densities are derived from observed ground-state lines, models, or rotational diagrams. We report here on two prototypical high-mass regions, AFGL 2591 and W3 IRS5, and compare them to chemical calculations making assumptions on the high-energy irradiation. A model assuming no ionizing protostellar emission is compared with (i) a model assuming strong protostellar X-ray emission and (ii) a two-dimensional (2D) model including emission in the far UV (FUV, 6 -- 13.6 eV) irradiating the outflow walls that separate the outflowing gas an...

  10. Chemically blockable transformation and ultraselective low-pressure gas adsorption in a non-porous metal organic framework.

    Xiao, Bo; Byrne, Peter J; Wheatley, Paul S; Wragg, David S; Zhao, Xuebo; Fletcher, Ashleigh J; Thomas, K Mark; Peters, Lars; Evans, John S O; Warren, John E; Zhou, Wuzong; Morris, Russell E


    Metal organic frameworks (MOFs) are among the most exciting materials discovered recently, attracting particular attention for their gas-adsorption and -storage properties. Certain MOFs show considerable structural flexibility in response to various stimuli. Although there are several examples of 'breathing' MOFs, in which structural changes occur without any bond breaking, examples of transformations in which several bonds are broken and made are much rarer. In this paper we demonstrate how a flexible MOF, Cu2(OH)(C8H3O7S)(H2O)2H2O, can be synthesized by careful choice of the organic linker ligand. The flexibility can be controlled by addition of a supplementary coordinating molecule, which increases the thermal stability of the solid sufficiently for direct imaging with electron microscopy to be possible. We also demonstrate that the MOF shows unprecedented low-pressure selectivity towards nitric oxide through a coordination-driven gating mechanism. The chemical control over these behaviours offers new possibilities for the synthesis of MOFs with unusual and potentially exploitable properties.

  11. Hyperthermal (1-100 eV) nitrogen ion scattering damage to D-ribose and 2-deoxy-D-ribose films.

    Deng, Zongwu; Bald, Ilko; Illenberger, Eugen; Huels, Michael A


    Highly charged heavy ion traversal of a biological medium can produce energetic secondary fragment ions. These fragment ions can in turn cause collisional and reactive scattering damage to DNA. Here we report hyperthermal (1-100 eV) scattering of one such fragment ion (N(+)) from biologically relevant sugar molecules D-ribose and 2-deoxy-D-ribose condensed on polycrystalline Pt substrate. The results indicate that N(+) ion scattering at kinetic energies down to 10 eV induces effective decomposition of both sugar molecules and leads to the desorption of abundant cation and anion fragments. Use of isotope-labeled molecules (5-(13)C D-ribose and 1-D D-ribose) partly reveals some site specificity of the fragment origin. Several scattering reactions are also observed. Both ionic and neutral nitrogen atoms abstract carbon from the molecules to form CN(-) anion at energies down to approximately 5 eV. N(+) ions also abstract hydrogen from hydroxyl groups of the molecules to form NH(-) and NH(2) (-) anions. A fraction of OO(-) fragments abstract hydrogen to form OH(-). The formation of H(3)O(+) ions also involves hydrogen abstraction as well as intramolecular proton transfer. These findings suggest a variety of severe damaging pathways to DNA molecules which occur on the picosecond time scale following heavy ion irradiation of a cell, and prior to the late diffusion-limited homogeneous chemical processes.

  12. Real-time quantification of traces of biogenic volatile selenium compounds in humid air by selected ion flow tube mass spectrometry.

    Sovová, Kristýna; Shestivska, Violetta; Španěl, Patrik


    Biological volatilization of selenium, Se, in a contaminated area is an economical and environmentally friendly approach to phytoremediation techniques, but analytical methods for monitoring and studying volatile compounds released in the process of phytovolatilization are currently limited in their performance. Thus, a new method for real time quantification of trace amounts of the vapors of hydrogen selenide (H(2)Se), methylselenol (CH(3)SeH), dimethylselenide ((CH(3))(2)Se), and dimethyldiselenide ((CH(3))(2)Se(2)) present in ambient air adjacent to living plants has been developed. This involves the characterization of the mechanism and kinetics of the reaction of H(3)O(+), NO(+), and O(2)(+•) reagent ions with molecules of these compounds and then use of the rate constants so obtained to determine their absolute concentrations in air by selected ion flow tube mass spectrometry, SIFT-MS. The results of experiments demonstrating this method on emissions from maize (Zea mays) seedlings cultivated in Se rich medium are also presented.

  13. Mass spectrometry of positive ions and neutral species in the effluent of an atmospheric pressure plasma with hexamethyldisiloxane and oxygen

    Benedikt, J.; Ellerweg, D.; Schneider, S.; Rügner, K.; R, Reuter; Kersten, H.; Benter, T.


    The effluent of a non-equilibrium atmospheric pressure plasma jet in He with admixture of hexamethyldisiloxane (HMDSO) and O2 has been investigated by means of molecular beam mass spectrometry. Positive ions and neutral plasma chemistry products have been detected and their possible role in the deposition of good-quality SiO2 films is discussed. Positive ion spectra reveal the presence of protonated water clusters and H+ : HMDSO and H3O+ : HMDSO ions. These ions are most probably produced by photoionization. This is corroborated by optical emission spectroscopy data obtained in the wavelength range of 50-300 nm, where helium excimer continuum emission centred around 84 nm has been observed. No ion driven polymerization products of HMDSO have been detected. Measurements of neutral species have allowed the quantification of the HMDSO depletion and absolute densities of trimethylsilanol and pentamethyldisiloxane. Two neutral polymerization products have been observed as well. The results indicate that the Si-O bond of HMDSO is preferentially broken. Additionally, the mass balance of plasma chemistry products is discussed.

  14. Insights into the Proton Transfer Mechanism of a Bilin Reductase PcyA Following Neutron Crystallography.

    Unno, Masaki; Ishikawa-Suto, Kumiko; Kusaka, Katsuhiro; Tamada, Taro; Hagiwara, Yoshinori; Sugishima, Masakazu; Wada, Kei; Yamada, Taro; Tomoyori, Katsuaki; Hosoya, Takaaki; Tanaka, Ichiro; Niimura, Nobuo; Kuroki, Ryota; Inaka, Koji; Ishihara, Makiko; Fukuyama, Keiichi


    Phycocyanobilin, a light-harvesting and photoreceptor pigment in higher plants, algae, and cyanobacteria, is synthesized from biliverdin IXα (BV) by phycocyanobilin:ferredoxin oxidoreductase (PcyA) via two steps of two-proton-coupled two-electron reduction. We determined the neutron structure of PcyA from cyanobacteria complexed with BV, revealing the exact location of the hydrogen atoms involved in catalysis. Notably, approximately half of the BV bound to PcyA was BVH(+), a state in which all four pyrrole nitrogen atoms were protonated. The protonation states of BV complemented the protonation of adjacent Asp105. The "axial" water molecule that interacts with the neutral pyrrole nitrogen of the A-ring was identified. His88 Nδ was protonated to form a hydrogen bond with the lactam O atom of the BV A-ring. His88 and His74 were linked by hydrogen bonds via H3O(+). These results imply that Asp105, His88, and the axial water molecule contribute to proton transfer during PcyA catalysis.

  15. The new metal complex templated polyoxoborate(s) (POB(s)) structures. Synthesis, structural characterization, and hydrogen storage capacities

    Ali Köse, Dursun; Yurdakul, Ömer; Şahin, Onur; Öztürk, Zeynel


    The polyoxoborate(s) (POB(s)) structures, including a neutral ligand-metal complex compound as a template, were synthesized and the structural characterizations were performed via single crystal X-ray diffraction, FTIR, 11B-NMR, solid state UV-Vis spectroscopy, SEM and elemental analysis methods. Moreover, the stabilization features were determined via TGA/DTA method. In addition, nitrogen and hydrogen adsorption measurements provided the realization to determine the pore size distribution, BET surface area, and hydrogen storage capacities. The molecular formulas of compounds were estimated as [Cu(C12H8N2)2(C2H3O2)][B5O6(OH)4]·2H3BO3·H2O (I) and [Ni(C12H8N2)2(H2O)2]·(B7O9(OH)5)·5H2O (II) and the existence of two different POB(s) structures as pentaborate (B5O6(OH)4) and heptaborate (B7O9(OH)5) within the compounds were observed. At last, it was found that the both structures have micro and mesoporosity with 0.407 and 1.480 m2/g BET surface areas, for the compound I and II, respectively. Moreover, within the same conditions, compound II could uptake 0.19 wt% hydrogen at 77 K and at the relative pressure of 1 while compound II uptakes 0.035 wt% hydrogen.

  16. Poly[(μ3-benzene-1,3,5-tricarboxylato-κ3O1:O3:O5(μ2-2-methylimidazolato-κ2N:N′tris(2-methylimidazole-κNdizinc(II

    Palanikumar Maniam


    Full Text Available Hydrothermal reaction involving zinc nitrate hexahydrate, trisodium benzene-1,3,5-tricarboxylate (Na3BTC and 2-methylimidazole (2-MeImH yielded the title compound, [Zn2(C9H3O6(C4H5N2(C4H6N23]. In this mixed-ligand metal-organic compound, Zn2+ ions are coordinated by N atoms from 2-MeImH molecules and (2-MeIm− ions, as well as by O atoms from (BTC3− ions. This results in two different distorted tetrahedra, viz. ZnN3O and ZnN2O2. These tetrahedra are interconnected via (BTC3− ions and N:N′-bridging (2-MeIm− ions, thus forming a layered structure in the bc plane. Hydrogen bonds between the O atoms of carboxylate ions and NH groups of 2-MeImH ligands link the layers into a three-dimensional structure.

  17. Diffusion and reaction pathways of water near fully hydrated TiO2 surfaces from ab initio molecular dynamics

    Agosta, Lorenzo; Brandt, Erik G.; Lyubartsev, Alexander P.


    Ab initio molecular dynamics simulations are reported for water-embedded TiO2 surfaces to determine the diffusive and reactive behavior at full hydration. A three-domain model is developed for six surfaces [rutile (110), (100), and (001), and anatase (101), (100), and (001)] which describes waters as "hard" (irreversibly bound to the surface), "soft" (with reduced mobility but orientation freedom near the surface), or "bulk." The model explains previous experimental data and provides a detailed picture of water diffusion near TiO2 surfaces. Water reactivity is analyzed with a graph-theoretic approach that reveals a number of reaction pathways on TiO2 which occur at full hydration, in addition to direct water splitting. Hydronium (H3O+) is identified to be a key intermediate state, which facilitates water dissociation by proton hopping between intact and dissociated waters near the surfaces. These discoveries significantly improve the understanding of nanoscale water dynamics and reactivity at TiO2 interfaces under ambient conditions.

  18. Toward a predictive understanding of water and charge transport in proton exchange membranes.

    Selvan, Myvizhi Esai; Calvo-Muñoz, Elisa; Keffer, David J


    An analytical model for water and charge transport in highly acidic and highly confined systems such as proton exchange membranes of fuel cells is developed and compared to available experimental data. The model is based on observations from both experiment and multiscale simulation. The model accounts for three factors in the system including acidity, confinement, and connectivity. This model has its basis in the molecular-level mechanisms of water transport but has been coarse-grained to the extent that it can be expressed in an analytical form. The model uses the concentration of H(3)O(+) ion to characterize acidity, interfacial surface area per water molecule to characterize confinement, and percolation theory to describe connectivity. Several important results are presented. First, an integrated multiscale simulation approach including both molecular dynamics simulation and confined random walk theory is capable of quantitatively reproducing experimentally measured self-diffusivities of water in the perfluorinated sulfonic acid proton exchange membrane material, Nafion. The simulations, across a range of hydration conditions from minimally hydrated to fully saturated, have an average error for the self-diffusivity of water of 16% relative to experiment. Second, accounting for three factors-acidity, confinement, and connectivity-is necessary and sufficient to understand the self-diffusivity of water in proton exchange membranes. Third, an analytical model based on percolation theory is capable of quantitatively reproducing experimentally measured self-diffusivities of both water and charge in Nafion across a full range of hydration.

  19. Multifunctional uranyl hybrid materials: structural diversities as a function of pH, luminescence with potential nitrobenzene sensing, and photoelectric behavior as p-type semiconductors.

    Song, Jian; Gao, Xue; Wang, Zhi-Nan; Li, Cheng-Ren; Xu, Qi; Bai, Feng-Ying; Shi, Zhong-Feng; Xing, Yong-Heng


    A series of uranyl-organic frameworks (UOFs), {[(UO2)2(H2TTHA)(H2O)]·4,4'-bipy·2H2O}n (1), {[(UO2)3(TTHA)(H2O)3]}n (2), and {[(UO2)5(TTHA) (HTTHA)(H2O)3]·H3O}n (3), have been obtained by the hydrothermal reaction of uranyl acetate with a flexible hexapodal ligand (1,3,5-triazine-2,4,6-triamine hexaacetic acid, H6TTHA). These compounds exhibited three distinct 3D self-assembly architectures as a function of pH by single-crystal structural analysis, although the used ligand was the same in each reaction. Surprisingly, all of the coordination modes of the H6TTHA ligand in this work are first discovered. Furthermore, the photoluminescent results showed that these compounds displayed high-sensitivity luminescent sensing functions for nitrobenzene. Additionally, the surface photovoltage spectroscopy and electric-field-induced surface photovoltage spectroscopy showed that compounds 1-3 could behave as p-type semiconductors.

  20. Crystal structure of ilyukhinite, a new mineral of the eudialyte group

    Rastsvetaeva, R. K.; Rozenberg, K. A.; Chukanov, N. V.; Aksenov, S. M.


    The crystal structure of ilyukhinite, a new mineral of the eudialyte group, is studied by X-ray diffraction. The mineral found in pegmatite bodies of the Kukisvumchorr Mountain (Khibiny alkaline complex) is characterized by low sodium content, high degree of hydration, and predominance of manganese over iron. The trigonal cell has the following parameters: a = 14.1695(6) and c = 31.026(1) Å; space group R3m. The structure is refined to final R = 0.046 in the anisotropic approximation of atomic displacements using 1527 F > 3σ F. The idealized formula of ilyukhinite ( Z = 3) is written as (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 · 3H2O. The new mineral differs from other representatives of the eudialyte group by the predominance of both oxonium in the N positions of extra-framework cations and manganese in the M2 position centering the tetragonal pyramid.

  1. Linking two distinct layered networks of nanosized {Ln18} and {Cu24} wheels through isonicotinate ligands.

    Cheng, Jian-Wen; Zhang, Jie; Zheng, Shou-Tian; Yang, Guo-Yu


    A new series of heterolanthanide(III)-copper(I) wheel-cluster complexes [Ln6(micro3-O)2](IN)18-[Cu8(micro4-I)2(micro2-I)3].H3O (IN=isonicotinate; Ln=Y 1, Nd 2, Dy 3, Gd 4, Sm 5, Eu 6, Tb 7) were prepared by hydrothermal reaction at low pH. X-ray crystallographic studies reveal that two unusual trinuclear [Ln3(micro3-O)] and tetranuclear [Cu4(micro4-I)] cores are successfully used as secondary building units to make two different nanosized wheels [Ln18(micro3-O)6(CO2)48](6-), {Ln18}, and [Cu24(micro4-I)6(micro2-I)12]6+, {Cu24}, with 12-rings and a diameter of 26.7 and 26.4 A, respectively. The wheels are further assembled into two-dimensional (2D) {Ln18} and {Cu24} networks, the linkages between two distinct layered networks of {Ln18} and {Cu24} wheels by IN pillars along the c axis giving a series of unprecedented three-dimensional (3D) sandwich frameworks. To our knowledge, compounds 1-7 are the first examples containing two different layered networks of nanosized Ln and transition metal (TM) wheels in wheel-cluster chemistry. The IR, UV/Vis, thermogravimetric analysis (TGA), luminescent, and magnetic properties of these complexes were also studied.

  2. Improvement in ionization efficiency of direct analysis in real time-mass spectrometry (DART-MS) by corona discharge.

    Sekimoto, Kanako; Sakakura, Motoshi; Kawamukai, Takatomo; Hike, Hiroshi; Shiota, Teruhisa; Usui, Fumihiko; Bando, Yasuhiko; Takayama, Mitsuo


    Herein it is shown that a combination of direct analysis in real time (DART) with a corona discharge system consisting of only a needle electrode easily improves DART ionization efficiency. Positive and negative DC corona discharges led to a formation of abundant excited helium atoms as well as the reactant ions H3O(+)(H2O)n and O2˙(-) in the DART analyte ionization area. These phenomena resulted in an increase in the absolute intensities of (de)protonated analytes by a factor of 2-20 over conventional DART. The other analyte ions detected in this corona-DART system (i.e., molecular ions, fragment ions, oxygenated (de)protonated analytes, dehydrogenated deprotonated analytes, and negative ion adducts) were quite similar to those obtained from DART alone. This indicates a lack of side reactions due to the corona discharge. The change in the relative intensities of individual analyte-related ions due to the combination of a corona discharge system with DART suggests that there is no effect of the abundant excited helium in the analyte ionization area on the fragmentation processes or enhancement of oxidation due to hydroxyl radicals HO˙. Furthermore, it was found that the corona-DART combination can be applied to the highly sensitive analysis of n-alkanes, in which the alkanes are ionized as positive ions via hydride abstraction and oxidation, independent of the type of alkane or the mass spectrometer used.

  3. A Molecular Dynamic Simulation of Hydrated Proton Transfer in Perfluorosulfonate Ionomer Membranes (Nafion 117

    Hong Sun


    Full Text Available A molecular dynamic model based on Lennard-Jones Potential, the interaction force between two particles, molecular diffusion, and radial distribution function (RDF is presented. The diffusion of the hydrated ion, triggered by both Grotthuss and vehicle mechanisms, is used to study the proton transfer in Nafion 117. The hydrated ion transfer mechanisms and the effects of the temperature, the water content in the membrane, and the electric field on the diffusion of the hydrated ion are analyzed. The molecular dynamic simulation results are in good agreement with those reported in the literature. The modeling results show that when the water content in Nafion 117 is low, H3O+ is the main transfer ion among the different hydrated ions. However, at higher water content, the hydrated ion in the form of H+(H2O2 is the main transfer ion. It is also found that the negatively charged sulfonic acid group as the fortified point facilitates the proton transfer in Nafion 117 better than the free water molecule. The diffusion of the hydrated ion can be improved by increasing the cell temperature, the water content in Nafion, and the electric field intensity.

  4. Modifying the reactivity in the homologation of propane by introducing aryloxide ligands on a silica supported zirconium alkyl system.

    Guillemot, Geoffroy; Thieuleux, Chloé; Copéret, Christophe; Soulivong, Daravong; Spitzmesser, Stefan; Basset, Jean-Marie


    Grafting the well-defined molecular complexes [(ArO)Zr(CH2tBu)3], , and [(ArO)2Zr(CH2tBu)2], , on SiO2-(700) (ArO=2,6-Ph2C6H3O) gives the corresponding monosiloxy surface complexes [([TRIPLE BOND]SiO)Zr(CH2tBu)2(OAr)] and [([TRIPLE BOND]SiO)Zr(CH2tBu)(OAr)2] as major surface species as evidenced by mass balance analysis, IR and NMR spectroscopies. In both cases, minor cyclometallated species (ca. 20%) are also probably formed during the grafting process. While /SiO2-(700) catalytically transforms propane into its lower and higher homologues, /SiO2-(700) remains inactive. Moreover, the formation of butane as the major higher homologues is consistent with the formation of metallocarbene intermediates in this system in contrast to what was observed for the corresponding homologation reaction on silica supported zirconium hydrides.

  5. Physical conditions in the central molecular zone inferred by H3+

    Petit, Franck Le; Bron, Emeric; Godard, Benjamin; Roueff, Evelyne; Languignon, David; Bourlot, Jacques Le


    The H3+ molecule has been detected in many lines of sight within the central molecular zone (CMZ) with exceptionally large column densities and unusual excitation properties compared to diffuse local clouds. The detection of the (3,3) metastable level has been suggested to be the signature of warm and diffuse gas in the CMZ. We use the Meudon PDR code to re-examine the relationship between the column density of H3+ and the cosmic-ray ionization rate, $\\zeta$, up to large values of $\\zeta$. We study the impact of the various mechanisms that can excite H3+ in its metastable state. We produce grids of PDR models exploring different parameters ($\\zeta$, size of clouds, metallicity) and infer the physical conditions that best match the observations toward ten lines of sight in the CMZ. For one of them, Herschel observations of HF, OH+, H2O+, and H3O+ can be used as additional constraints. We check that the results found for H3+ also account for the observations of these molecules. We find that the linear relations...

  6. Oxonium (dihydrogen 1-amino-ethane-1,1-diyldiphospho-nato-κN,O)[hydrogen (1-amino-1-phosphono-ethyl)phospho-nato-κN,O]palladium(II) trihydrate.

    Dudko, Anatolij; Bon, Vladimir; Kozachkova, Alexandra; Tsaryk, Natalia; Pekhnyo, Vasily


    The title compound, (H(3)O)[Pd(C(2)H(7)NO(6)P(2))(C(2)H(8)NO(6)P(2))]·3H(2)O, was synthesized by the reaction of [Pd(H(2)O)(4)](NO(3))(2) with 1-amino-ethane-1,1-diyldiphospho-nic acid in aqueous solution. The asymmetric unit contains one mol-ecule of the complex existing as an anion, an oxonium counter-ion and three solvent water mol-ecules. The Pd(II) ion occupies a position on a pseudo-twofold axis, which is not realized crystallographically. The slightly distorted square-planar coordination environment of the Pd(II) ion consists of the O atoms from two phospho-nic acid groups and two N atoms of the amino groups in cis positions. The crystal structure displays N-H⋯O and O-H⋯O hydrogen bonding, which creates a wide three-dimensional network.

  7. Experimental and kinetic modeling study of C2H4 oxidation at high pressure

    Lopez, Jorge Gimenez; Rasmussen, Christian Lund; Alzueta, Maria;


    A detailed chemical kinetic model for oxidation of C2H4 in the intermediate temperature range and high pressure has been developed and validated experimentally. New ab initio calculations and RRKM analysis of the important C2H3 + O-2 reaction was used to obtain rate coefficients over a wide range...... of conditions (0.003-100 bar, 200-3000 K). The results indicate that at 60 bar and medium temperatures vinyl peroxide, rather than CH2O and HCO, is the dominant product. The experiments, involving C2H4/O-2 mixtures diluted in N-2, were carried out in a high pressure flow reactor at 600-900 K and 60 bar, varying...... the reaction stoichiometry from very lean to fuel-rich conditions. Model predictions are generally satisfactory. The governing reaction mechanisms are outlined based on calculations with the kinetic model. Under the investigated conditions the oxidation pathways for C2H4 are more complex than those prevailing...

  8. Longitudinal Distribution of the Dayside Ionosphere of Mars at High Latitude

    Haider, S. A.; Sheel, Varun; Singh, V.; Maguire, W. C.; Molina-Cuberos, G. J.


    Accelerometer and radio science data obtained from Mars Global Surveyor have been used to study the longitudinal structure of thermosphere and troposphere of Mars at high latitude region. These datasets represent primary and secondary ionization peaks at altitudes 130 km and 122 km, respectively. These peaks are reproduced by photoionization and photoelectron impact processes. The production rates of different ions are estimated in the thermosphere and troposphere at solar zenith angle 80°, using analytical yield spectrum and energy loss models, respectively. The electron densities are calculated under photochemical equilibrium condition. The impact ionization sources are taken as EUV and galactic cosmic rays. The characteristics of longitudinal distribution of production and density are fitted up to waves 2 and 3 by least square method with 0.95 confidence limits. The peak electron density in the troposphere is obtained at an altitude of 30 km due to high efficiency of electron attachment to Ox molecules, which entails that concentration of negative ions is higher than that of electron below 30 km. Of the 35 ions considered in the model, the densities of electron and nine major ions (H3O+(H2O)n for n = 1,2,3,4, notation="LaTeX">CO^{-}_{4}, notation="LaTeX">CO^{-}_{3}, notation="LaTeX">NO^{-}_{2}H_{2}O, and notation="LaTeX">CO^{-}_{3}(H_{2}O)_{n} for n = 1,2) are discussed.

  9. Influence of pH value on the evolution and the crystal structure of manganese sulfate skeleton%pH控制硫酸锰骨架的演化及其晶体结构

    王璐; 孙丽; 宋江锋; 周瑞莎


    在DMF/H2 O/CH3 OH的混合体系中,反应温度为170℃,MnSO4·4H2 O盐溶液在pH=5和7的条件下,加热72小时,最终得到了结构不同的硫酸锰骨架[Mn2(SO4)3]·(H3O)2(1)和[Mn3(SO4)2(OH)2(H2O)2](2)。化合物结构通过单晶X-射线和红外光谱所表征,相应的晶胞参数:化合物1,立方晶系,空间群:P213,a=10.2009(12)Å,V=1061.49(37)Å3,GooF=1.158,Flack parameter 0.02(2),R1=0.0186(I>2sigma);化合物2,四方晶系,空间群:Pbcm,a=7.3214(15)Å,b=9.984(2)Å,c=13.291(3)Å,V=971.5(4)Å3,GooF=1.063, R1=0.0227(I>2sigma);单晶X射线分析显示化合物1是一个三维单手性硫酸锰骨架,化合物2是一个非手性羟基硫酸锰骨架。实验结果说明,pH值对硫酸锰骨架的改变起重要作用。%Under the mixed DMF/H2 O/CH3 OH,the MnSO4·4H2 O solution was heated for 72 hours at 170℃ at pH values 5 and 7, respectively,two manganese sulfate skeleton,[Mn2(SO4)3]·(H3O)2(1) and[Mn3(SO4)2(OH)2(H2O)2] (2) were ob-tained. Compounds 1 and 2 are characterized through single crystal X-ray diffraction and infrared spectrum. The corresponding cell parameters for compound 1,cubic crystal system,space group P213,a=10. 2009(12)Å,V=1061. 49(37)Å3,GooF=1. 158,Flack parameter 0. 02(2),R1=0. 0186(I>2sigma);for compound 2,tetragonal crystal system,space group Pbcm,a=7. 3214(15)Å,b=9. 984(2)Å,c=13. 291(3)Å,V=971. 5(4)Å3,GooF=1. 063,R1=0. 0227(I>2sigma). Single crystal X ray analysis showed that compound 1 is a 3D single chiral manganese sulfate skeleton however, compound 2 is a hydroxy manganese sulfate skele-ton. Experimental results show that pH value plays an important role in the evolution of manganese sulfate skeleton.

  10. Chemical, crystallographic and stable isotopic properties of alunite and jarosite from acid-Hypersaline Australian lakes

    Alpers, C.N.; Rye, R.O.; Nordstrom, D.K.; White, L.D.; King, B.-S.


    Chemical, crystallographic and isotopic analyses were made on samples containing alunite and jarosite from the sediments of four acid, hypersaline lakes in southeastern and southwestern Australia. The alunite and jarosite are K-rich with relatively low Na contents based on chemical analysis and determination of unit cell dimensions by powder X-ray diffraction. Correcting the chemical analyses of fine-grained mineral concentrates from Lake Tyrrell, Victoria, for the presence of halite, silica and poorly crystalline aluminosilicates, the following formulas indicate best estimates for solid-solution compositions: for alunite, K0.87Na0.04(H3O)0.09(Al 0.92Fe0.08)3(SO4)2(OH) 6 and for jarosite, K0.89Na0.07(H3O)0.04(Fe 0.80Al0.20)3(SO4)2(OH) 6. The ??D-values of alunite are notably larger than those for jarosite from Lake Tyrrell and it appears that the minerals have closely approached hydrogen isotope equilibrium with the acidic regional groundwaters. The ??D results are consistent with a fractionation ???60-70??? between alunite and jarosite observed in other areas. However, interpretation of ??D results is complicated by large variability in fluid ??DH2O from evaporation, mixing and possible ion hydration effects in the brine. ??D-values of water derived from jarosite by step-wise heating tend to be smaller at 250??C, at which temperature hydronium and other non-hydroxyl water is liberated, than at 550??C, where water is derived from the hydroxyl site, but the differences are not sufficiently different to invalidate measurements of total ??D obtained by conventional, single-step heating methods. ??34S-values for alunite and jarosite from the four lakes (+19.7 to +21.2??? CDT) and for aqueous sulfate from Lake Tyrrell (+18.3 to +19.8???) are close to the values for modern evaporites (+21.5 ??0.3???) and seawater (+20??0.5???) and are probably typical of seawater-derived aerosols in arid coastal environments. ??34-S-values slightly smaller than that for seawater may

  11. Proton Transfers at the Air-Water Interface

    Mishra, Himanshu

    Proton transfer reactions at the interface of water with hydrophobic media, such as air or lipids, are ubiquitous on our planet. These reactions orchestrate a host of vital phenomena in the environment including, for example, acidification of clouds, enzymatic catalysis, chemistries of aerosol and atmospheric gases, and bioenergetic transduction. Despite their importance, however, quantitative details underlying these interactions have remained unclear. Deeper insight into these interfacial reactions is also required in addressing challenges in green chemistry, improved water quality, self-assembly of materials, the next generation of micro-nanofluidics, adhesives, coatings, catalysts, and electrodes. This thesis describes experimental and theoretical investigation of proton transfer reactions at the air-water interface as a function of hydration gradients, electrochemical potential, and electrostatics. Since emerging insights hold at the lipid-water interface as well, this work is also expected to aid understanding of complex biological phenomena associated with proton migration across membranes. Based on our current understanding, it is known that the physicochemical properties of the gas-phase water are drastically different from those of bulk water. For example, the gas-phase hydronium ion, H3O +(g), can protonate most (non-alkane) organic species, whereas H 3O+(aq) can neutralize only relatively strong bases. Thus, to be able to understand and engineer water-hydrophobe interfaces, it is imperative to investigate this fluctuating region of molecular thickness wherein the 'function' of chemical species transitions from one phase to another via steep gradients in hydration, dielectric constant, and density. Aqueous interfaces are difficult to approach by current experimental techniques because designing experiments to specifically sample interfacial layers (quantum mechanics and molecular dynamics to simulate our experiments toward gaining insight at the

  12. Ion energy distributions and densities in the plume of Enceladus

    Sakai, Shotaro; Cravens, Thomas E.; Omidi, Nojan; Perry, Mark E.; Waite, J. Hunter


    Enceladus has a dynamic plume that is emitting gas, including water vapor, and dust. The gas is ionized by solar EUV radiation, charge exchange, and electron impact and extends throughout the inner magnetosphere of Saturn. The charge exchange collisions alter the plasma composition. Ice grains (dust) escape from the vicinity of Enceladus and form the E ring, including a portion that is negatively charged by the local plasma. The inner magnetosphere within 10 RS (Saturn radii) contains a complex mixture of plasma, neutral gas, and dust that links back to Enceladus. In this paper we investigate the energy distributions, ion species and densities of water group ions in the plume of Enceladus using test particle and Monte Carlo methods that include collisional processes such as charge exchange and ion-neutral chemical reactions. Ion observations from the Cassini Ion and Neutral Mass Spectrometer (INMS) for E07 are presented for the first time. We use the modeling results to interpret observations made by the Cassini Plasma Spectrometer (CAPS) and the INMS. The low energy ions, as observed by CAPS, appear to be affected by a vertical electric field (EZ=-10 μV/m) in the plume. The EZ field may be associated with the charged dust and/or the pressure gradient of plasma. The model results, along with the results of earlier models, show that H3O+ ions created by chemistry are predominant in the plume, which agrees with INMS and CAPS data, but the INMS count rate in the plume for the model is several times greater than the data, which we do not fully understand. This composition and the total ion count found in the plume agree with INMS and CAPS data. On the other hand, the Cassini Langmuir Probe measured a maximum plume ion density more than 30,000 cm-3, which is far larger than the maximum ion density from our model, 900 cm-3. The model results also demonstrate that most of the ions in the plume are from the external magnetospheric flow and are not generated by local

  13. A study on the dissolution rates of K-Cr(VI)-jarosites: kinetic analysis and implications.

    Reyes, Iván A; Mireles, Ister; Patiño, Francisco; Pandiyan, Thangarasu; Flores, Mizraim U; Palacios, Elia G; Gutiérrez, Emmanuel J; Reyes, Martín


    The presence of natural and industrial jarosite type-compounds in the environment could have important implications in the mobility of potentially toxic elements such as lead, mercury, arsenic, chromium, among others. Understanding the dissolution reactions of jarosite-type compounds is notably important for an environmental assessment (for water and soil), since some of these elements could either return to the environment or work as temporary deposits of these species, thus would reduce their immediate environmental impact. This work reports the effects of temperature, pH, particle diameter and Cr(VI) content on the initial dissolution rates of K-Cr(VI)-jarosites (KFe3[(SO4)2 - X(CrO4)X](OH)6). Temperature (T) was the variable with the strongest effect, followed by pH in acid/alkaline medium (H3O(+)/OH(-)). It was found that the substitution of CrO4 (2-)in Y-site and the substitution of H3O(+) in M-site do not modify the dissolution rates. The model that describes the dissolution process is the unreacted core kinetic model, with the chemical reaction on the unreacted core surface. The dissolution in acid medium was congruent, while in alkaline media was incongruent. In both reaction media, there is a release of K(+), SO4 (2-) and CrO4 (2-) from the KFe3[(SO4)2 - X(CrO4)X](OH)6 structure, although the latter is rapidly absorbed by the solid residues of Fe(OH)3 in alkaline medium dissolutions. The dissolution of KFe3[(SO4)2 - X(CrO4)X](OH)6 exhibited good stability in a wide range of pH and T conditions corresponding to the calculated parameters of reaction order n, activation energy E A and dissolution rate constants for each kinetic stages of induction and progressive conversion. The kinetic analysis related to the reaction orders and calculated activation energies confirmed that extreme pH and T conditions are necessary to obtain considerably high dissolution rates. Extreme pH conditions (acidic or alkaline) cause the preferential release of K(+), SO4 (2

  14. Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

    Xu, Lingling; Chen, Jinsheng


    Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

  15. Radiolysis of Sulfuric Acid, Sulfuric Acid Monohydrate, and Sulfuric Acid Tetrahydrate and Its Relevance to Europa

    Loeffler, M. J.; Hudson, R. L.; Moore, M. H.; Carlson, R. W.


    We report laboratory studies on the 0.8 MeV proton irradiation of ices composed of sulfuric acid (H2SO4), sulfuric acid monohydrate (H2SO4 H2O), and sulfuric acid tetrahydrate (H2SO4 4H2O) between 10 and 180 K. Using infrared spectroscopy, we identify the main radiation products as H2O, SO2, (S2O3)x, H3O+, HSO4(exp -), and SO4(exp 2-). At high radiation doses, we find that H2SO4 molecules are destroyed completely and that H2SO4 H2O is formed on subsequent warming. This hydrate is significantly more stable to radiolytic destruction than pure H2SO4, falling to an equilibrium relative abundance of 50% of its original value on prolonged irradiation. Unlike either pure H2SO4 or H2SO4 H2O, the loss of H2SO4 4H2O exhibits a strong temperature dependence, as the tetrahydrate is essentially unchanged at the highest irradiation temperatures and completely destroyed at the lowest ones, which we speculate is due to a combination of radiolytic destruction and amorphization. Furthermore, at the lower temperatures it is clear that irradiation causes the tetrahydrate spectrum to transition to one that closely resembles the monohydrate spectrum. Extrapolating our results to Europa s surface, we speculate that the variations in SO2 concentrations observed in the chaotic terrains are a result of radiation processing of lower hydration states of sulfuric acid and that the monohydrate will remain stable on the surface over geological times, while the tetrahydrate will remain stable in the warmer regions but be destroyed in the colder regions, unless it can be reformed by other processes, such as thermal reactions induced by diurnal cycling.

  16. Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS for the measurement of atmospherically significant oxygenated volatile organic compounds

    K. P. Wyche


    Full Text Available The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence supported oxygenated volatile organic compound (OVOC measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0–0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+ as the primary chemical ionization (CI reagent in order to facilitate proton transfer to the analyte OVOCs. The results presented show that the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs at mixing ratios of around 10 ppbV in "real-time" (i.e. detection on the one-minute time scale, with sub-ppbV measurement also achieved following an increase in averaging time to tens of minutes. It is shown that in general OVOC measurement is made with high accuracy and precision, with integration time, mixing ratio and compound dependent values as good as 4–13% and 3–15% respectively. It is demonstrated that CIR-TOF-MS has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurement.

  17. Photocatalytic reduction of Cr(VI) on the novel hetero-system CuFe(2)O(4)/CdS.

    Nasrallah, N; Kebir, M; Koudri, Z; Trari, M


    The photocatalytic HCrO(4)(-) reduction was investigated in air equilibrated solution using the spinel CuFe(2)O(4) nanoparticles as sensitizers. The oxide is p-type semi conductor, prepared from nitrates decomposition. The catalytic performance increases with decreasing pH and the concomitant oxidation of salicylic acid contributes significantly to the photoactivity through the charges separation of electron/hole pairs (C(7)H(6)O(3)+6 O(2)+4h(+)+3 H(2)O → 7 CO(2)+4 H(3)O(+)). Evidence has been given to show the advantages of the hetero-system CuFe(2)O(4)/CdS in the chromate reduction. CuFe(2)O(4) acts as electrons pump and the electron transfer to chromate is mediated via CdS hexagonal variety (greenockite). A reduction of 60% occurs and the process is well described by a pseudo first order kinetic with a half life of ∼2.8h and a quantum yield of ∼0.12% for an initial HCrO(4)(-) concentration of 3 × 10(-4)M. An improvement up to 72% is obtained when the reaction occurs in a stirred reactor and no cadmium was detected after 6h illumination. The results indicate a competitive effect with the water reduction. The hydrogen evolutions are found to be 0.236 and 0.960 cm(3)mn(-1)g(-1) in presence and in absence of HCrO(4)(-), respectively.

  18. Characteristic and in vitro bioactivity of a microarc-oxidized TiO(2)-based coating after chemical treatment.

    Wei, Daqing; Zhou, Yu; Jia, Dechang; Wang, Yaming


    Microarc oxidation (MAO) was used to prepare a TiO(2)-based coating containing Ca and P on titanium alloy. An alkali treatment was developed to modify the surface of the MAO coating to improve the apatite-forming ability of the coating. The chemically treated MAO coating exhibits a modified layer, with the main constituents being O, Ti, Ca and Na, showing anatase. The modified MAO coating shows a rough and porous morphology containing numerous nanoflakes of approximately 100nm thickness. During the alkali treatment process, P on the surface of the MAO coating shows a main dynamic process of dissolution; however, Ca exhibits a re-deposition process as well as dissolution. The formation of the modified layer could be explained by this mechanism: negatively charged HTiO(3)(-) ions are formed on the MAO coating due to the attack of OH(-) ions on the TiO(2) phase. The HTiO(3)(-) ions could incorporate sodium from the alkali solution and calcium from the alkali solution and MAO coating. The apatite-forming ability of the MAO coating is improved remarkably by the simple chemical treatment, since the surface of the alkali-treated MAO coating could provide abundant Ti-OH groups probably formed by ionic exchanges between (Ca2+, Na+) ions of the alkali-treated MAO coating and H3O+ ions of a simulated body fluid (SBF). Moreover, Ca released from the alkali-treated MAO coating increases the degree of supersaturation of SBF, promoting the formation of apatite. The apatite induced by the alkali-treated MAO coating possesses carbonated structure and pore networks on the nanometer scale.

  19. Biomass pyrolysis: Thermal decomposition mechanisms of furfural and benzaldehyde

    Vasiliou, AnGayle K.; Kim, Jong Hyun; Ormond, Thomas K.; Piech, Krzysztof M.; Urness, Kimberly N.; Scheer, Adam M.; Robichaud, David J.; Mukarakate, Calvin; Nimlos, Mark R.; Daily, John W.; Guan, Qi; Carstensen, Hans-Heinrich; Ellison, G. Barney


    The thermal decompositions of furfural and benzaldehyde have been studied in a heated microtubular flow reactor. The pyrolysis experiments were carried out by passing a dilute mixture of the aromatic aldehydes (roughly 0.1%-1%) entrained in a stream of buffer gas (either He or Ar) through a pulsed, heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 75-150 Torr with the SiC tube wall temperature in the range of 1200-1800 K. Characteristic residence times in the reactor are 100-200 μsec after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 μTorr. Products were detected using matrix infrared absorption spectroscopy, 118.2 nm (10.487 eV) photoionization mass spectroscopy and resonance enhanced multiphoton ionization. The initial steps in the thermal decomposition of furfural and benzaldehyde have been identified. Furfural undergoes unimolecular decomposition to furan + CO: C4H3O-CHO (+ M) → CO + C4H4O. Sequential decomposition of furan leads to the production of HC≡CH, CH2CO, CH3C≡CH, CO, HCCCH2, and H atoms. In contrast, benzaldehyde resists decomposition until higher temperatures when it fragments to phenyl radical plus H atoms and CO: C6H5CHO (+ M) → C6H5CO + H → C6H5 + CO + H. The H atoms trigger a chain reaction by attacking C6H5CHO: H + C6H5CHO → [C6H6CHO]* → C6H6 + CO + H. The net result is the decomposition of benzaldehyde to produce benzene and CO.

  20. Selective measurements of isoprene and 2-methyl-3-buten-2-ol based on NO+ ionization mass spectrometry

    W. Jud


    Full Text Available Biogenic VOC emissions are often dominated by 2-methyl-1,3-butadiene (isoprene and 2-methyl-3-buten-2-ol (232 MBO. Here we explore the possibility for selectively distinguishing these species using NO+ as primary ion based on PTR-MS technology. High purity of NO+ (>90% as a primary ion was achieved in laboratory and field experiments using a PTR-TOF-MS. Isoprene is ionized via charge transfer leading to the major product ion C5H8+ (>99% (e.g. Spanel and Smith, 1998. 232 MBO undergoes a hydroxide ion transfer reaction resulting in the major product ion channel C5H9+ (>95% (e.g. Amelynck et al., 2005. We show that both compounds are ionized with little fragmentation (−1 were achieved, which correspond to limit of detections of 18 and 15 pptv, respectively for a 10 s integration time. Sensitivities decreased at higher collisional energies. Calibration experiments showed little humidity dependence. We tested the setup at a field site in Colorado dominated by ponderosa pine, a 232 MBO emitting plant species. Our measurements confirm 232 MBO as the dominant biogenic VOC at this site, exhibiting typical average daytime concentrations between 0.2–1.4 ppbv. The method is able to detect the presence of trace levels of isoprene (90–250 ppt without any interference from 232 MBO, which would not be feasible using H3O+ ionization chemistry, and which currently also remains achallenge for other analytical techniques (e.g. gas chromatographic methods.

  1. Selective measurements of isoprene and 2-methyl-3-buten-2-ol based on NO+ ionization mass spectrometry

    W. Jud


    Full Text Available Biogenic VOC emissions are often dominated by 2-methyl-1,3-butadiene (isoprene and 2-methyl-3-buten-2-ol (232 MBO. Here we explore the possibility to selectively distinguish these species using NO+ as a primary ion in a conventional PTR-MS equipped with an SRI unit. High purity of NO+ (>90% as a primary ion was utilized in laboratory and field experiments using a conventional PTR-TOF-MS. Isoprene is ionized via charge transfer leading to the major product ion C5H8+ (>99% (e.g. Spanel and Smith, 1998. 232 MBO undergoes a hydroxide ion transfer reaction resulting in the major product ion channel C5H9+ (>95% (e.g. Amelynck et al., 2005. We show that both compounds are ionized with little fragmentation (>5% under standard operating conditions. Typical sensitivities of 11.1 ± 0.1 (isoprene and 12.9 ± 0.1 (232 MBO ncps ppbv−1 were achieved, which correspond to limit of detections of 18 and 15 pptv respectively for a 10 s integration time. Sensitivities decreased at higher collisional energies. Calibration experiments showed little humidity dependence. We tested the setup at a field site in Colorado dominated by ponderosa pine, a 232 MBO emitting plant species. Our measurements confirm 232 MBO as the dominant biogenic VOC at this site, exhibiting typical average daytime concentrations between 0.2–1.4 ppbv. The method is able to detect the presence of trace levels of isoprene at this field site (90–250 ppt without any interference from 232 MBO, which would not be feasible using H3O+ ionization chemistry, and which currently also remains a challenge for other analytical techniques (e.g. gas chromatographic methods.

  2. Modification of histones by sugar β-N-acetylglucosamine (GlcNAc) occurs on multiple residues, including histone H3 serine 10, and is cell cycle-regulated.

    Zhang, Suisheng; Roche, Kevin; Nasheuer, Heinz-Peter; Lowndes, Noel Francis


    The monosaccharide, β-N-acetylglucosamine (GlcNAc), can be added to the hydroxyl group of either serines or threonines to generate an O-linked β-N-acetylglucosamine (O-GlcNAc) residue (Love, D. C., and Hanover, J. A. (2005) Sci. STKE 2005 312, 1-14; Hart, G. W., Housley, M. P., and Slawson, C. (2007) Nature 446, 1017-1022). This post-translational protein modification, termed O-GlcNAcylation, is reversible, analogous to phosphorylation, and has been implicated in many cellular processes. Here, we present evidence that in human cells all four core histones of the nucleosome are substrates for this glycosylation in the relative abundance H3, H4/H2B, and H2A. Increasing the intracellular level of UDP-GlcNAc, the nucleotide sugar donor substrate for O-GlcNAcylation enhanced histone O-GlcNAcylation and partially suppressed phosphorylation of histone H3 at serine 10 (H3S10ph). Expression of recombinant H3.3 harboring an S10A mutation abrogated histone H3 O-GlcNAcylation relative to its wild-type version, consistent with H3S10 being a site of histone O-GlcNAcylation (H3S10glc). Moreover, O-GlcNAcylated histones were lost from H3S10ph immunoprecipitates, whereas immunoprecipitation of either H3K4me3 or H3K9me3 (active or inactive histone marks, respectively) resulted in co-immunoprecipitation of O-GlcNAcylated histones. We also examined histone O-GlcNAcylation during cell cycle progression. Histone O-GlcNAcylation is high in G(1) cells, declines throughout the S phase, increases again during late S/early G(2), and persists through late G(2) and mitosis. Thus, O-GlcNAcylation is a novel histone post-translational modification regulating chromatin conformation during transcription and cell cycle progression.

  3. Water-lactose behavior as a function of concentration and presence of lactic acid in lactose model systems.

    Wijayasinghe, Rangani; Vasiljevic, Todor; Chandrapala, Jayani


    The presence of high amounts of lactic acid in acid whey restricts its ability to be further processed because lactose appears to remain in its amorphous form. A systematic study is lacking in this regard especially during the concentration step. Hence, the main aim of the study was to establish the structure and behavior of water molecules surrounding lactose in the presence of 1% (wt/wt) lactic acid at a concentration up to 50% (wt/wt). Furthermore, the crystallization nature of freeze-dried lactose with or without lactic acid was established using differential scanning calorimetry and Fourier transform infrared spectroscopy. Two mechanisms were proposed to describe the behavior of water molecules around lactose molecules during the concentration of pure lactose and lactose solutions with lactic acid. Pure lactose solution exhibited a water evaporation enthalpy of ~679 J·g(-1), whereas lactose+ lactic acid solution resulted in ~965 J·g(-1) at a 50% (wt/wt) concentration. This indicates a greater energy requirement for water removal around lactose in the presence of lactic acid. Higher crystallization temperatures were observed with the presence of lactic acid, indicating a delay in crystallization. Furthermore, less crystalline lactose (~12%) was obtained in the presence of lactic acid, indicating high amorphous nature compared with pure lactose where ~50% crystallinity was obtained. The Fourier transform infrared spectra revealed that the strong hydration layer consisting lactic acid and H3O(+) ions surrounded lactose molecules via strong H bonds, which restricted water mobility, induced a change in structure of lactose, or both, creating unfavorable conditions for lactose crystallization. Thus, partial or complete removal of lactic acid from acid whey may be the first step toward improving the ability of acid whey to be processed.

  4. The oxidation of tyrosine and tryptophan studied by a molecular dynamics normal hydrogen electrode.

    Costanzo, Francesca; Sulpizi, Marialore; Della Valle, Raffaele Guido; Sprik, Michiel


    The thermochemical constants for the oxidation of tyrosine and tryptophan through proton coupled electron transfer in aqueous solution have been computed applying a recently developed density functional theory (DFT) based molecular dynamics method for reversible elimination of protons and electrons. This method enables us to estimate the solvation free energy of a proton (H(+)) in a periodic model system from the free energy for the deprotonation of an aqueous hydronium ion (H(3)O(+)). Using the computed solvation free energy of H(+) as reference, the deprotonation and oxidation free energies of an aqueous species can be converted to pK(a) and normal hydrogen electrode (NHE) potentials. This conversion requires certain thermochemical corrections which were first presented in a similar study of the oxidation of hydrobenzoquinone [J. Cheng, M. Sulpizi, and M. Sprik, J. Chem. Phys. 131, 154504 (2009)]. Taking a different view of the thermodynamic status of the hydronium ion, these thermochemical corrections are revised in the present work. The key difference with the previous scheme is that the hydronium is now treated as an intermediate in the transfer of the proton from solution to the gas-phase. The accuracy of the method is assessed by a detailed comparison of the computed pK(a), NHE potentials and dehydrogenation free energies to experiment. As a further application of the technique, we have analyzed the role of the solvent in the oxidation of tyrosine by the tryptophan radical. The free energy change computed for this hydrogen atom transfer reaction is very similar to the gas-phase value, in agreement with experiment. The molecular dynamics results however, show that the minimal solvent effect on the reaction free energy is accompanied by a significant reorganization of the solvent.

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

    Chevrot, G; Schurhammer, R; Wipff, G


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

  6. Novel pre-treatment of zeolite materials for the removal of sodium ions: potential materials for coal seam gas co-produced wastewater.

    Santiago, Oscar; Walsh, Kerry; Kele, Ben; Gardner, Edward; Chapman, James


    Coal seam gas (CSG) is the extraction of methane gas that is desorbed from the coal seam and brought to the surface using a dewatering and depressurisation process within the saturated coalbed. The extracted water is often referred to as co-produced CSG water. In this study, co-produced water from the coal seam of the Bowen Basin (QLD, Australia) was characterised by high concentration levels of Na(+) (1156 mg/L), low concentrations of Ca(2+) (28.3 mg/L) and Mg(2+) (5.6 mg/L), high levels of salinity, which are expected to cause various environmental problems if released to land or waters. The potential treatment of co-produced water using locally sourced natural ion exchange (zeolite) material was assessed. The zeolite material was characterized for elemental composition and crystal structure. Natural, untreated zeolite demonstrated a capacity to adsorb Na(+) ions of 16.16 mEq/100 g, while a treated zeolite using NH4 (+) using a 1.0 M ammonium acetate (NH4C2H3O2) solution demonstrated an improved 136 % Na(+) capacity value of 38.28 mEq/100 g after 720 min of adsorption time. The theoretical exchange capacity of the natural zeolite was found to be 154 mEq/100 g. Reaction kinetics and diffusion models were used to determine the kinetic and diffusion parameters. Treated zeolite using a NH4 (+) pre-treatment represents an effective treatment to reduce Na(+) concentration in coal seam gas co-produced waters, supported by the measured and modelled kinetic rates and capacity.

  7. FTIR adsorption studies of H2O and CH3OH in the isostructural H-SSZ-13 and H-SAPO-34: formation of H-bonded adducts and protonated clusters.

    Bordiga, Silvia; Regli, Laura; Lamberti, Carlo; Zecchina, Adriano; Bjørgen, Morten; Lillerud, Karl Petter


    The acidity of the isostructural H-SSZ-13 and H-SAPO-34 has been investigated by transmission FTIR spectroscopy using H2O and CH3OH as molecular probes. Interactions between the zeolitic samples and the probe molecules led to perturbations and proton transfers directly related to the acidity of the materials. The entire set of acidic sites in H-SSZ-13 interacts with H2O and CH3OH to give H-bonded adducts or protonated species. H3O+ is not formed in appreciable amounts upon H2O adsorption on H-SSZ-13, but at high coverages H2O generates clusters that have a proton affinity sufficiently high to abstract protons from the zeolite framework. Parallel experiments carried out for H-SAPO-34 showed that the H2O clusters abstract protons from Brønsted sites only to a minor extent. Moving to CH3OH, even if it has a higher proton affinity than H2O and should expectingly experience an easier protonation, proton transfer is totally absent in H-SAPO-34 under our set of conditions. The clear evidence of methanol protonation in H-SSZ-13 definitely states the strong acidic character of this material. When irreversibly adsorbed CH3OH is present in H-SSZ-13, an appreciable amount of (CH3)2O is formed upon heating to 573 K. Compared to its SAPO analogue, the present set of data indisputably points to H-SSZ-13 as the strongest Brønsted acidic material.

  8. Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

    Bu, Wei [Iowa State Univ., Ames, IA (United States)


    Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. The experimental ion distributions are in excellent agreement with a renormalized surface charge Poisson-Boltzmann theory for monovalent ions without fitting parameters or additional assumptions. Energy Scans at four fixed momentum transfers under specular reflectivity conditions near the Cs+ L3 resonance were conducted on 10-3 M CsI with DHDP monolayer materials on the surface. The energy scans exhibit a periodic dependence on photon momentum transfer. The ion distributions obtained from the analysis are in excellent agreement with those obtained from anomalous reflectivity measurements, providing further confirmation to the validity of the renormalized surface charge Poisson-Boltzmann theory for monovalent ions. Moreover, the dispersion corrections f0 and f00 for Cs+ around L3 resonance, revealing the local environment of a Cs+ ion in the solution at the interface, were extracted simultaneously with output of ion distributions.

  9. Quantitative detection of benzene in toluene- and xylene-rich atmospheres using high-kinetic-energy ion mobility spectrometry (IMS).

    Langejuergen, Jens; Allers, Maria; Oermann, Jens; Kirk, Ansgar; Zimmermann, Stefan


    One major drawback of ion mobility spectrometry (IMS) is the dependence of the response to a certain analyte on the concentration of water or the presence of other compounds in the sample gas. Especially for low proton affine analytes, e.g., benzene, which often exists in mixtures with other volatile organic compounds, such as toluene and xylene (BTX), a time-consuming preseparation is necessary. In this work, we investigate BTX mixtures using a compact IMS operated at decreased pressure (20 mbar) and high kinetic ion energies (HiKE-IMS). The reduced electric field in both the reaction tube and the drift tube can be independently increased up to 120 Td. Under these conditions, the water cluster distribution of reactant ions is shifted toward smaller clusters independent of the water content in the sample gas. Thus, benzene can be ionized via proton transfer from H3O(+) reactant ions. Also, a formation of benzene ions via charge transfer from NO(+) is possible. Furthermore, the time for interaction between ions and neutrals of different analytes is limited to such an extent that a simultaneous quantification of benzene, toluene, and xylene is possible from low ppbv up to several ppmv concentrations. The mobility resolution of the presented HiKE-IMS varies from R = 65 at high field (90 Td) to R = 73 at lower field (40 Td) in the drift tube, which is sufficient to separate the analyzed compounds. The detection limit for benzene is 29 ppbv (2 s of averaging) with 3700 ppmv water, 12.4 ppmv toluene, and 9 ppmv xylene present in the sample gas. Furthermore, a less-moisture-dependent benzene measurement with a detection limit of 32 ppbv with ca. 21 000 ppmv (90% relative humidity (RH) at 20 °C) water present in the sample gas is possible evaluating the signal from benzene ions formed via charge transfer.

  10. A comparison of the ion chemistry for mono-substituted toluenes and anilines by three methods of atmospheric pressure ionization with ion mobility spectrometry.

    Borsdorf, H; Neitsch, K; Eiceman, G A; Stone, J A


    Ion mobility spectra for a series of mono-substituted toluenes and a series of mono-substituted anilines were obtained using three different methods of atmospheric pressure ionization including photoionization, chemical ionization from a (63)Ni source, and chemical ionization from a corona discharge source. The product ion peak intensities were measured as functions of analyte concentration at 323 K in a purified air atmosphere. Two, and sometimes three, product ion peaks were observed in spectra from chemical ionization with the (63)Ni source and it is suggested that the major peak, due to the protonated molecule, arose in both series by proton transfer from H3O+(H2O)n. The second peak with diminished intensity and longer drift time than the protonated molecule can be seen with the toluenes and was understood to be the NO+ adduct, formed from the reactant ion NO+(H2O)n. Electron transfer from the anilines to the latter ion yields the molecular ions, identified by having the same reduced mobility coefficients as the molecular ions produced by photoionization. The structure of these product ions was determined by investigations using the coupling of ion mobility spectrometry with atmospheric pressure photoionization and mass spectrometry (APPI-IMS-MS). The relative abundances of both the NO+ adducts with the toluenes and the molecular ions with the anilines are enhanced with a corona discharge source where relatively more NO+(H2O)n is produced than in a (63)Ni source. Ab initio calculations show that only the protonated anilines of all the product ions are significantly hydrated with 1 ppm(v) of moisture in the supporting atmosphere of the ion mobility spectrometer.

  11. Production of methyl vinyl ketone and methacrolein via the hydroperoxyl pathway of isoprene oxidation

    Y. J. Liu


    Full Text Available The photo-oxidation chemistry of isoprene (ISOP; C5H8 was studied in a continuous-flow chamber under conditions such that the reactions of the isoprene-derived peroxyl radicals (RO2 were dominated by the hydroperoxyl (HO2 pathway. A proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS with switchable H3O+ and NO+ reagent ions was used for product analysis. The products methyl vinyl ketone (MVK; C4H6O and methacrolein (MACR; C4H6O were differentiated using NO+ reagent ions. The MVK and MACR yields via the HO2 pathway were (3.8 ± 1.3% and (2.5 ± 0.9%, respectively, at +25 °C and 2 pathway implies concomitant production of hydroxyl ((6.3 ± 2.1% and hydroperoxyl ((6.3 ± 2.1% radicals, meaning a HOx recycling of (12.6 ± 4.2% given that HO2 was both a reactant and product. Other isoprene oxidation products, believed to be mostly organic hydroperoxides, also contributed to the ion intensity at the same mass-to-charge (m/z ratios as the MVK and MACR product ions for HO2-dominant conditions. These products were selectively removed from the gas phase by placement of a cold trap (−40 °C inline prior to the PTR-TOF-MS. When incorporated into regional and global chemical transport models, the yields of MVK and MACR and the concomitant HOx recycling reported in this study can improve the accuracy of the simulation of the HO2 reaction pathway of isoprene, which is believed to be the fate of approximately half of atmospherically produced isoprene-derived peroxy radicals on a global scale.

  12. Synthetic Tuning of Redox, Spectroscopic, and Photophysical Properties of {Mo6I8}(4+) Core Cluster Complexes by Terminal Carboxylate Ligands.

    Mikhailov, Maxim A; Brylev, Konstantin A; Abramov, Pavel A; Sakuda, Eri; Akagi, Soichiro; Ito, Akitaka; Kitamura, Noboru; Sokolov, Maxim N


    The reactions between the tetra-n-butylammonium salt of [{Mo6I8}I6](2-) and silver carboxylates RCOOAg (R = CH3 (1), C(CH3)3 (2), α-C4H3O (3), C6H5 (4), α-C10H7 (5), or C2F5 (6)) in CH2Cl2 afforded new carboxylate complexes [{Mo6I8}(RCOO)6](2-). The complexes were characterized by X-ray single-crystal diffraction and elemental analysis, cyclic/differential pulse voltammetry, and IR, NMR, and UV-visible spectroscopies. The emission properties of the complexes 1-6, and those of the earlier reported complexes with R = CF3 (7) and n-C3F7 (8), were studied both in acetonitrile solution and in the solid state. In deaerated CH3CN at 298 K, all of the complexes 1-8 exhibit intense and long-lived emission with the quantum yield and lifetime being 0.48-0.73 and 283-359 μs, respectively. The oxidation (Eox)/reduction (Ered) potentials of the complexes correlate linearly with the pKa value of the terminal carboxylate ligands L = RCOO (pKa(L)). Reflecting the pKa(L) dependences of Eox/Ered, the emission energy (νem) of the complexes was also shown to correlate with pKa(L). The present study successfully demonstrates synthetic tuning of the redox, spectroscopic, and photophysical characteristics of a {Mo6I8}(4+)-based cluster complex with pKa(L).

  13. 细菌性阴道病微生态与益生菌%Microecology, bacterial vaginosis and probiotics

    沈定树; 梁平; 彭敏飞


    Bacterial vaginosis is the most common cause of vaginitis in women of childbearing age. The disorder represents a complex change in vaginal flora characterized by a reduction in the prevalence and concentration of lactobacilli. Probiotics enriched in lactobacilli have been proposed as an effective and alternative tool to antibiotics for the treatment of bacterial vaginosis. In vitro studies have suggested that certain specific strains of lactobacilli are able to inhibit the adherence of Gardnerella vagi-nalis to the vaginal epithelium and /or produce H3O2, lactic acid and/or bacteriocins, which inhibit the growth of bacteria causing BV. This is of outstanding interest due to the central role of polyamines in the pathogenesis of bacterial vaginosis.%细菌性阴道病(BV)是育龄妇女阴道炎的最常见原因,其特征是栖居在阴道内的乳酸杆菌减少导致阴道菌群平衡失调的复杂变化.用乳酸杆菌替代抗生素是治疗BV的一种有效的治疗措施.乳酸杆菌产生过氧化氢、乳酸、杆菌素能抑制引起BV的细菌生长.多胺在BV的病理机制中有重要作用.本研究拟综述BV患者阴道菌群的变化,免疫防御反应,阴道乳酸杆菌对BV的影响,多胺的意义,益生菌在治疗选择中的作用.

  14. The Mg2+-containing Water Cluster of Mammalian Cytochrome c Oxidase Collects Four Pumping Proton Equivalents in Each Catalytic Cycle.

    Yano, Naomine; Muramoto, Kazumasa; Shimada, Atsuhiro; Takemura, Shuhei; Baba, Junpei; Fujisawa, Hidenori; Mochizuki, Masao; Shinzawa-Itoh, Kyoko; Yamashita, Eiki; Tsukihara, Tomitake; Yoshikawa, Shinya


    Bovine heart cytochrome c oxidase (CcO) pumps four proton equivalents per catalytic cycle through the H-pathway, a proton-conducting pathway, which includes a hydrogen bond network and a water channel operating in tandem. Protons are transferred by H3O(+) through the water channel from the N-side into the hydrogen bond network, where they are pumped to the P-side by electrostatic repulsion between protons and net positive charges created at heme a as a result of electron donation to O2 bound to heme a3 To block backward proton movement, the water channel remains closed after O2 binding until the sequential four-proton pumping process is complete. Thus, the hydrogen bond network must collect four proton equivalents before O2 binding. However, a region with the capacity to accept four proton equivalents was not discernable in the x-ray structures of the hydrogen bond network. The present x-ray structures of oxidized/reduced bovine CcO are improved from 1.8/1.9 to 1.5/1.6 Å resolution, increasing the structural information by 1.7/1.6 times and revealing that a large water cluster, which includes a Mg(2+) ion, is linked to the H-pathway. The cluster contains enough proton acceptor groups to retain four proton equivalents. The redox-coupled x-ray structural changes in Glu(198), which bridges the Mg(2+) and CuA (the initial electron acceptor from cytochrome c) sites, suggest that the CuA-Glu(198)-Mg(2+) system drives redox-coupled transfer of protons pooled in the water cluster to the H-pathway. Thus, these x-ray structures indicate that the Mg(2+)-containing water cluster is the crucial structural element providing the effective proton pumping in bovine CcO.

  15. Emissions of volatile organic compounds (VOCs) from concentrated animal feeding operations (CAFOs): chemical compositions and separation of sources

    Yuan, Bin; Coggon, Matthew M.; Koss, Abigail R.; Warneke, Carsten; Eilerman, Scott; Peischl, Jeff; Aikin, Kenneth C.; Ryerson, Thomas B.; de Gouw, Joost A.


    Concentrated animal feeding operations (CAFOs) emit a large number of volatile organic compounds (VOCs) to the atmosphere. In this study, we conducted mobile laboratory measurements of VOCs, methane (CH4) and ammonia (NH3) downwind of dairy cattle, beef cattle, sheep and chicken CAFO facilities in northeastern Colorado using a hydronium ion time-of-flight chemical-ionization mass spectrometer (H3O+ ToF-CIMS), which can detect numerous VOCs. Regional measurements of CAFO emissions in northeastern Colorado were also performed using the NOAA WP-3D aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX) campaign. Alcohols and carboxylic acids dominate VOC concentrations and the reactivity of the VOCs with hydroxyl (OH) radicals. Sulfur-containing and phenolic species provide the largest contributions to the odor activity values and the nitrate radical (NO3) reactivity of VOC emissions, respectively. VOC compositions determined from mobile laboratory and aircraft measurements generally agree well with each other. The high time-resolution mobile measurements allow for the separation of the sources of VOCs from different parts of the operations occurring within the facilities. We show that the emissions of ethanol are primarily associated with feed storage and handling. Based on mobile laboratory measurements, we apply a multivariate regression analysis using NH3 and ethanol as tracers to determine the relative importance of animal-related emissions (animal exhalation and waste) and feed-related emissions (feed storage and handling) for different VOC species. Feed storage and handling contribute significantly to emissions of alcohols, carbonyls, carboxylic acids and sulfur-containing species. Emissions of phenolic species and nitrogen-containing species are predominantly associated with animals and their waste.

  16. Pickup Ions in the Plasma Environments of Mars, Comets, and Enceladus

    Cravens, T.; Rahmati, A.; Sakai, S.; Madanian, H.; Larson, D. E.; Lillis, R. J.; Halekas, J. S.; Goldstein, R.; Burch, J. L.; Clark, G. B.; Jakosky, B. M.


    Ions created within a flowing plasma by ionization of neutrals respond to the electric and magnetic fields associated with the flow becoming what are called pick-up ions (PUI). PUI play an important role in many solar system plasma environments and affect the energy and momentum balance of the plasma flow. PUI have been observed during several recent space missions and PUI data will be compared and interpreted using models. Pick-up oxygen ions were observed in the solar wind upstream of Mars by the Solar Energetic Particle (SEP) and Solar Wind Ion Analyzer (SWIA) instruments on NASA's MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft. The pick-up oxygen ions are created when atoms in the hot corona are ionized by solar radiation and charge exchange with solar wind protons. The ion fluxes measured by SEP can constrain the oxygen escape rate from Mars. PUI were also been detected at distances of 10 - 100 km from the nucleus of comet 67P/Churyumov- Gerasimenko (67P/CG) by plasma instruments (IES and ICA) onboard the Rosetta Orbiter when the comet was at 3 AU. The newly-born cometary ions are accelerated by the solar wind motional electric field but remain un-magnetized, as suggested by pre-encounter models (Rubin et al., 2014). The inner magnetosphere of Saturn and the water plume of the icy satellite Enceladus provide a third example of PUI. H2O+ ions created by ionization of neutral water producing ions that are picked-up by the co-rotating magnetospheric plasma flow. These ions then undergo a complex interaction with the plume gas including collisions that convert most H2O+ ions to H3O+, as measured by the Ion and Neutral Mass Spectrometer (INMS) onboard the Cassini spacecraft.

  17. Progress in SIFT-MS: breath analysis and other applications.

    Spaněl, Patrik; Smith, David


    The development of selected ion flow tube mass spectrometry, SIFT-MS, is described from its inception as the modified very large SIFT instruments used to demonstrate the feasibility of SIFT-MS as an analytical technique, towards the smaller but bulky transportable instruments and finally to the current smallest Profile 3 instruments that have been located in various places, including hospitals and schools to obtain on-line breath analyses. The essential physics and engineering principles are discussed, which must be appreciated to design and construct a SIFT-MS instrument. The versatility and sensitivity of the Profile 3 instrument is illustrated by typical mass spectra obtained using the three precursor ions H(3)O(+), NO(+) and O(2)(+)·, and the need to account for differential ionic diffusion and mass discrimination in the analytical algorithms is emphasized to obtain accurate trace gas analyses. The performance of the Profile 3 instrument is illustrated by the results of several pilot studies, including (i) on-line real time quantification of several breath metabolites for cohorts of healthy adults and children, which have provided representative concentration/population distributions, and the comparative analyses of breath exhaled via the mouth and nose that identify systemic and orally-generated compounds, (ii) the enhancement of breath metabolites by drug ingestion, (iii) the identification of HCN as a marker of Pseudomonas colonization of the airways and (iv) emission of volatile compounds from urine, especially ketone bodies, and from skin. Some very recent developments are discussed, including the quantification of carbon dioxide in breath and the combination of SIFT-MS with GC and ATD, and their significance. Finally, prospects for future SIFT-MS developments are alluded to.

  18. Ambient analysis of trace compounds in gaseous media by SIFT-MS.

    Smith, David; Spaněl, Patrik


    The topic of ambient gas analysis has been rapidly developed in the last few years with the evolution of the exciting new techniques such as DESI, DART and EESI. The essential feature of all is that analysis of trace gases can be accomplished either in the gas phase or those released from surfaces, crucially avoiding sample collection or modification. In this regard, selected ion flow tube mass spectrometry, SIFT-MS, also performs ambient analyses both accurately and rapidly. In this focused review we describe the underlying ion chemistry underpinning SIFT-MS through a discourse on the reactions of different classes of organic and inorganic molecules with H(3)O(+), NO(+) and O(2)(+)˙ studied using the SIFT technique. Rate coefficients and ion products of these reactions facilitate absolute SIFT-MS analyses and can also be useful for the interpretation of data obtained by the other ambient analysis methods mentioned above. The essential physics and flow dynamics of SIFT-MS are described that, together with the reaction kinetics, allow SIFT-MS to perform absolute ambient analyses of trace compounds in humid atmospheric air, exhaled breath and the headspace of aqueous liquids. Several areas of research that, through pilot experiments, are seen to benefit from ambient gas analysis using SIFT-MS are briefly reviewed. Special attention is given to exhaled breath and urine headspace analysis directed towards clinical diagnosis and therapeutic monitoring, and some other areas researched using SIFT-MS are summarised. Finally, extensions to current areas of application and indications of other directions in which SIFT-MS can be exploited for ambient analysis are alluded to.

  19. Determination of the deuterium abundances in water from 156 to 10,000 ppm by SIFT-MS.

    Španěl, Patrik; Shestivska, Violetta; Chippendale, Thomas W E; Smith, David


    In response to a need for the measurement of the deuterium (D) abundance in water and aqueous liquids exceeding those previously recommended when using flowing afterglow mass spectrometry (FA-MS) and selected ion flow tube mass spectrometry (SIFT-MS) (i.e. 1000 parts per million, ppm), we have developed the theory of equilibrium isotopic composition of the product ions on which these analytical methods are based to encompass much higher abundances of D in water up to 10,000 ppm (equivalent to 1%). This has involved an understanding of the number density distributions of the H, D, (16)O, (17)O and (18)O isotopes in the isotopologues of H(3)O(+)(H(2)O)(3) hydrated ions (i.e. H(9)O (4) (+) cluster ions) at mass-to-charge ratios (m/z) of 73, 74 and 75, the relative ion number densities of which represent the basis of FA-MS and SIFT-MS analyses of D abundance. Specifically, an extended theory has been developed that accounts for the inclusion of D atoms in the m/z 75 ions, which increasingly occurs as D abundance in the water is increased, and which is used as a reference signal for the m/z 74 ions in the measurement of D abundance. In order to investigate the efficacy of this theory, experimental measurements of deuterium abundance in standard mixtures were made by the SIFT-MS technique using two similar instruments and the results compared with the theory. It is demonstrated that the parameterization of experimental data can be used to formulate a simple calculation algorithm for real-time SIFT-MS measurements of D abundance to an accuracy of 1% below 1000 ppm and degrades to about 2% at 10,000 ppm.

  20. Efficient nickel mediated carbon-carbon bond cleavage of organonitriles.

    Schaub, Thomas; Döring, Christian; Radius, Udo


    The reactions of the nickel complex [Ni(2)(iPr(2)Im)4(COD)] 1 with organonitriles smoothly and irreversibly proceed via intermediates with eta(2)-coordinated organonitrile ligands such as [Ni(iPr(2)Im)2(eta(2)-(CN)-PhCN)] 2 and [Ni(iPr(2)Im)2(eta(2)-(CN)-pTolCN)] 4 to yield aryl cyanide complexes of the type trans-[Ni(iPr(2)Im)2(CN)(Ar)] (Ar = Ph 3, pTol 5, 4-CF(3)C(6)H(4) 6, 2,4-(OMe)2C(6)H(3) 7, 2-C(4)H(3)O 8, 2-C(5)H(4)N 9). The compounds 3, 7, 9 and have been structurally characterized. For the conversion of 2 to 3 a free activation enthalpy DeltaG++(328 K) of 103.47 +/- 0.79 kJ mol(-1) was calculated from time dependent NMR spectroscopy. The analogous reaction of arylnitriles with electron releasing substituents or heteroaromatic organonitriles is significantly faster compared to the reaction with benzonitrile or toluonitrile. The reactions of 1 with acetonitrile or trimethylsilyl cyanide afforded [Ni(iPr(2)Im)2(CN)(Me)] 10 and structurally characterized [Ni(iPr(2)Im)2(CN)(SiMe(3))] 11. The usage of an organonitrile with a longer alkyl chain, adiponitrile, yielded [Ni(iPr(2)Im)2(eta(2)-(CN)-NCC(4)H(8)CN)] 12 as well as the C-CN activation product [Ni(iPr(2)Im)2(CN)(C(4)H(8)CN)]13 in thermal and photochemical reactions, although this pathway seems to be significantly interfered with by decomposition pathways under the formation of the dicyanide complex [Ni(iPr(2)Im)(2)(CN)(2)] 14.

  1. Are protonated ions efficient sequestration agents for noble gases in the primitive nebula context?

    Pauzat, Françoise; Ellinger, Yves; ozgurel, Ozge; Bacchus-montabonel, Marie-christine; Mousis, Olivier; Laboratoire de Chimie Théorique, Institut Lumière Matière, Laboratoire d'Astrophysique de Marseille


    One explanation for the deficiencies of argon, krypton and xenon observed in the atmosphere of Titan might be related to a scenario of sequestration by H3+ in the gas phase at the early evolution of the solar nebula. The chemical process implied is a radiative association, evaluated as rather efficient in the case of H3+, especially for krypton and xenon. In fact, this mechanism of chemical trapping might not be limited to H3+ only, considering that the protonated ions produced in the destruction of H3+ by its main competitors, namely H2O, CO and N2, present in the primitive nebula, might also give stable complexes with the noble gases.Here, the reactivity of the noble gases Ar, Kr, Xe, with all the protonated ions issued from H2O, CO and N2, expected to be present in the nebula with reasonably high abundances, i.e. H3O+, HCO+, HOC+, N2H+, has been studied with quantum simulation methods, quantum dynamics included. All of them give stable complexes; the rate coefficients of their radiative associations have been calculated as a function of temperature between 10 and 100 °K and found ranging from 10-18 to 10-16 cm3s-1, which can be considered as high for this type of reactions and are comparable to the rates obtained with H3+.Consequently, we can consider this process as universal for all protonated ions, which, if present in the primitive nebula as astrophysical models predict, should act as efficient sequestration agents for all three noble gases, in addition to the original H3+ captor.

  2. A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

    Cox, Robin A.


    If a species does not have a finite lifetime in the reaction medium, it cannot be a mechanistic intermediate. This principle was first enunciated by Jencks, as the concept of an enforced mechanism. For instance, neither primary nor secondary carbocations have long enough lifetimes to exist in an aqueous medium, so SN1 reactions involving these substrates are not possible, and an SN2 mechanism is enforced. Only tertiary carbocations and those stabilized by resonance (benzyl cations, acylium ions) are stable enough to be reaction intermediates. More importantly, it is now known that neither H3O+ nor HO− exist as such in dilute aqueous solution. Several recent high-level calculations on large proton clusters are unable to localize the positive charge; it is found to be simply “on the cluster” as a whole. The lifetime of any ionized water species is exceedingly short, a few molecular vibrations at most; the best experimental study, using modern IR instrumentation, has the most probable hydrated proton structure as H13O6+, but only an estimated quarter of the protons are present even in this form at any given instant. Thanks to the Grotthuss mechanism of chain transfer along hydrogen bonds, in reality a proton or a hydroxide ion is simply instantly available anywhere it is needed for reaction. Important mechanistic consequences result. Any charged oxygen species (e.g., a tetrahedral intermediate) is also not going to exist long enough to be a reaction intermediate, unless the charge is stabilized in some way, usually by resonance. General acid catalysis is the rule in reactions in concentrated aqueous acids. The Grotthuss mechanism also means that reactions involving neutral water are favored; the solvent is already highly structured, so the entropy involved in bringing several solvent molecules to the reaction center is unimportant. Examples are given. PMID:22272074

  3. Proton transport in triflic acid hydrates studied via path integral car-parrinello molecular dynamics.

    Hayes, Robin L; Paddison, Stephen J; Tuckerman, Mark E


    The mono-, di-, and tetrahydrates of trifluoromethanesulfonic acid, which contain characteristic H(3)O(+), H(5)O(2)(+), and H(9)O(4)(+) structures, provide model systems for understanding proton transport in materials with high perfluorosulfonic acid density such as perfluorosulfonic acid membranes commonly employed in hydrogen fuel cells. Ab initio molecular dynamics simulations indicate that protons in these solids are predisposed to transfer to the water most strongly bound to sulfonate groups via a Grotthuss-type mechanism, but quickly return to the most solvated defect structure either due to the lack of a nearby species to stabilize the new defect or a preference for the proton to be maximally hydrated. Path integral molecular dynamics of the mono- and dihydrate reveal significant quantum effects that facilitate proton transfer to the "presolvated" water or SO(3)(-) in the first solvation shell and increase the Zundel character of all the defects. These trends are quantified in free energy profiles for each bonding environment. Hydrogen bonding criteria for HOH-OH(2) and HOH-O(3)S are extracted from the two-dimensional potential of mean force. The quantum radial distribution function, radius of gyration, and root-mean-square displacement position correlation function show that the protonic charge is distributed over two or more water molecules. Metastable structural defects with one excess proton shared between two sulfonate groups and another Zundel or Eigen type cation defect are found for the mono- and dihydrate but not for the tetrahydrate crystal. Results for the tetrahydrate native crystal exhibit minor differences at 210 and 250 K. IR spectra are calculated for all native and stable defect structures. Graph theory techniques are used to characterize the chain lengths and ring sizes in the hydrogen bond network. Low conductivities when limited water is present may be attributable to trapping of protons between SO(3)(-) groups and the increased

  4. Simultaneous Evaluation of Multiple Rotationally Excited States of Floppy Molecules Using Diffusion Monte Carlo

    McCoy, Anne B.; Ford, Jason E.; Marlett, Melanie L.; Petit, Andrew S.


    In this work, an extension to diffusion Monte Carlo (DMC) is proposed, allowing for the simultaneous calculation of the energy and wave function of multiple rotationally excited states of floppy molecules. The total wave function is expanded into a set of Dirac δ-functions called walkers, while the rotational portion of the wave function is expanded in a symmetric top basis set. Each walker is given a rotational state vector containing coefficients for all states of interest. The positions of the atoms and the coefficients in the state vector evolve according to the split operator approximation of the quantum propagator. The method was benchmarked by comparing calculated rotation-vibration energies for H_3^+, H_2D^+, and H_3O^+ to experimental values. For low to moderate values of J, the resulting energies are within the statistical uncertainty of the calculation. Rotation-vibration coupling is captured through flexibility introduced in the form of the vibrational wave function. This coupling is found to increase with increasing J-values. Based on the success achieved through these systems, the method was applied to CH_5^+ and its deuterated isotopologues for v = 0, J ≥ 10. Based on these calculations, the energy level structure of CH_5^+ is found to resemble that for a of a spherical top, and excitations up to J = 10 displayed insignificant rotation-vibration coupling. Extensions of this approach that explicitly account for vibrations will also be discussed. ` A. S. Petit, J. E. Ford and A. B. McCoy, J. Phys. Chem. A, in press, K. D. Jordan Festschrift, DOI: 10.1021/jp408821a

  5. Submillimeter Spectroscopy of Hydride Molecules

    Phillips, T. G.


    Simple hydride molecules are of great importance in astrophysics and astrochemistry. Physically they dominate the cooling of dense, warm phases of the ISM, such as the cores and disks of YSOs. Chemically they are often stable end points of chemical reactions, or may represent important intermediate stages of the reaction chains, which can be used to test the validity of the process. Through the efforts of astronomers, physicists, chemists, and laboratory spectroscopists we have an approximate knowledge of the abundance of some of the important species, but a great deal of new effort will be required to achieve the comprehensive and accurate data set needed to determine the energy balance and firmly establish the chemical pathways. Due to the low moment of inertia, the hydrides rotate rapidly and so have their fundamental spectral lines in the submillimeter. Depending on the cloud geometry and temperature profile they may be observed in emission or absorption. Species such as HCl, HF, OH, CH, CH(+) , NH_2, NH_3, H_2O, H_2S, H_3O(+) and even H_3(+) have been detected, but this is just a fraction of the available set. Also, most deduced abundances are not nearly sufficiently well known to draw definitive conclusions about the chemical processes. For example, the most important coolant for many regions, H_2O, has a possible range of deduced abundance of a factor of 1000. The very low submillimeter opacity at the South Pole site will be a significant factor in providing a new capabilty for interstellar hydride spectroscopy. The new species and lines made available in this way will be discussed.

  6. Expression of the mammalian renal peptide transporter PEPT2 in the yeast Pichia pastoris and applications of the yeast system for functional analysis.

    Döring, F; Michel, T; Rösel, A; Nickolaus, M; Daniel, H


    It has recently been identified the PEPT2 cDNA encodes the high affinity proton-coupled peptide transporter in rabbit kidney cortex. PEPT2 represents a 729 amino acid protein with 12 putative transmembrane domains that mediates H+/H3O+ dependent electrogenic transmembrane transport of di- and tripeptides and of selected peptidomimetics. Here the functional expression of PEPT2 in the methylotropic yeast Pichia pastoris is described under the control of a methanol inducible promoter. Western blot analysis of Pichia cell membranes prepared from a recombinant clone identified a protein with an apparent molecular mass of about 85-87 kDa. Peptide uptake into cells expressing PEPT2 was up to 80 times higher than in control cells. Cells of recombinant clones showed a saturable peptide transport activity for the hydrolysis resistant dipeptide 3H-D-Phe-Ala with an app. K0.5 of 0.143 +/- 0.016 mM. Inhibition of 3H-D-Phe-Ala uptake by selected di- and tripeptides and beta-lactam antibiotics revealed the same substrate specificity as obtained in renal membrane vesicles or for PEPT2 when expressed in Xenopus laevis oocytes. A novel fluorescence based assay for assessing transport function based on a coumarin-labeled fluorescent peptide analogue has also been developed. Moreover, using a histidyl auxotrophe strain a PEPT2 expressing cell clone in which transport function can be monitored by a simple yeast growth test was established. In conclusion, this is one of only a few reports on successful functional expression of mammalian membrane transport proteins in yeast. The high expression level will provide a simple means for future studies either on the structure-affinity relationship for substrate interaction with PEPT2 or for selection of mutants generated by random mutagenesis.

  7. Communication: the origin of rotational enhancement effect for the reaction of H2O(+) + H2 (D2).

    Li, Anyang; Li, Yongle; Guo, Hua; Lau, Kai-Chung; Xu, Yuntao; Xiong, Bo; Chang, Yih-Chung; Ng, C Y


    We have measured the absolute integral cross sections (σ's) for H3O(+) formed by the reaction of rovibrationally selected H2O(+)(X(2)B1; v1 (+)v2 (+)v3 (+) = 000; N(+) K a (+) K c (+) = 000, 111, and 211) ion with H2 at the center-of-mass collision energy (Ecm) range of 0.03-10.00 eV. The σ(000), σ(111), and σ(211) values thus obtained reveal rotational enhancements at low Ecm Communication presents important progress concerning the high-level ab initio quantum calculation of the potential energy surface for the H2O(+)(X(2)B1) + H2 (D2) reactions, which has provided valuable insight into the origin of the rotational enhancement effect. Governed by the charge and dipole-induced-multipole interactions, the calculation shows that H2 (D2) approaches the H end of H2O(+)(X(2)B1) in the long range, whereas chemical force in the short range favors the orientation of H2 (D2) toward the O side of H2O(+). The reorientation of H2O(+) reactant ion facilitated by rotational excitation thus promotes the H2O(+) + H2 (D2) reaction along the minimum energy pathway, rendering the observed rotational enhancement effects. The occurrence of this effect at low Ecm indicates that the long range charge and dipole-induced-multipole interactions of the colliding pair play a significant role in the dynamics of the exothermic H2O(+) + H2 (D2) reactions.

  8. Frovatriptan salts of aliphatic carboxylic acids.

    Ravikumar, Krishnan; Sridhar, Balasubramanian; Nanubolu, Jagadeesh Babu; Hariharakrishnan, Venkatasubramanian; Rao, Bandi Venugopal


    The interaction of the antimigraine pharmaceutical agent frovatriptan with acetic acid and succinic acid yields the salts (±)-6-carbamoyl-N-methyl-2,3,4,9-tetrahydro-1H-carbazol-3-aminium acetate, C14H18N3O(+)·C2H3O2(-), (I), (R)-(+)-6-carbamoyl-N-methyl-2,3,4,9-tetrahydro-1H-carbazol-3-aminium 3-carboxypropanoate monohydrate, C14H18N3O(+)·C4H5O4(-)·H2O, (II), and bis[(R)-(+)-6-carbamoyl-N-methyl-2,3,4,9-tetrahydro-1H-carbazol-3-aminium] succinate trihydrate, 2C14H18N3O(+)·C4H4O4(2-)·3H2O, (III). The methylazaniumyl substitutent is oriented differently in all three structures. Additionally, the amide group in (I) is in a different orientation. All the salts form three-dimensional hydrogen-bonded structures. In (I), the cations form head-to-head hydrogen-bonded amide-amide catemers through N-H···O interactions, while in (II) and (III) the cations form head-to-head amide-amide dimers. The cation catemers in (I) are extended into a three-dimensional network through further interactions with acetate anion acceptors. The presence of succinate anions and water molecules in (II) and (III) primarily governs the three-dimensional network through water-bridged cation-anion associations via O-H···O and N-H···O hydrogen bonds. The structures reported here shed some light on the possible mode of noncovalent interactions in the aggregation and interaction patterns of drug molecule adducts.

  9. CF3(+) and CF2H(+): new reagents for n-alkane determination in chemical ionisation reaction mass spectrometry.

    Blake, Robert S; Ouheda, Saleh A; Evans, Corey J; Monks, Paul S


    Alkanes provide a particular analytical challenge to commonly used chemical ionisation methods such as proton-transfer from water owing to their basicity. It is demonstrated that the fluorocarbon ions CF3(+) and CF2H(+), generated from CF4, as reagents provide an effective means of detecting light n-alkanes in the range C2-C6 using direct chemical ionisation mass spectrometry. The present work assesses the applicability of the reagents in Chemical Ionisation Mass Spectrometric (CI-TOF-MS) environments with factors such as high moisture content, operating pressures of 1-10 Torr, accelerating electric fields (E/N) and long-lived intermediate complex formation. Of the commonly used chemical ionisation reagents, H3O(+) and NO(+) only react with hexane and higher while O2(+) reacts with all the target samples, but creates significant fragmentation. By contrast, CF3(+) and CF2H(+) acting together were found to produce little or no fragmentation. In dry conditions with E/N = 100 Td or higher the relative intensity of CF2H(+) to CF3(+) was mostly less than 1% but always less than 3%, making CF3(+) the main reagent ion. Using O2(+) in a parallel series of experiments, a substantially greater degree of fragmentation was observed. The detection sensitivities of the alkanes with CF3(+) and CF2H(+), while relatively low, were found to be better than those observed with O2(+). Experiments using alkane mixtures in the ppm range have shown the ionisation technique based on CF3(+) and CF2H(+) to be particularly useful for measurements of alkane/air mixtures found in polluted environments. As a demonstration of the technique's effectiveness in complex mixtures, the detection of n-alkanes in a smoker's breath is demonstrated.

  10. Molecules in the circumnuclear disk of the Galactic center

    Harada, Nanase; Riquelme, Denise; Viti, Serena; Menten, Karl; Requena-Torres, Miguel; Güsten, Rolf; Hochgürtel, Stefan


    Within a few parsecs around the central black hole A*, chemistry in the dense molecular cloud material of the circumnuclear disk (CND) can be affected by many energetic phenomena such as high UV-flux from the massive central star cluster, X-rays from A*, shock waves, and an enhanced cosmic-ray flux. Recently, spectroscopic surveys with the IRAM 30 meter and the APEX 12 meter telescopes of substantial parts of the 80-500 GHz frequency range were made toward selected positions in and near the CND. These data sets contain lines from the molecules HCN, HCO+, HNC, CS, SO, SiO, CN, H2CO, HC3N, N2H+, H3O+ and others. We conduct Large Velocity Gradient analyses to obtain column densities and total hydrogen densities, n, for each species in molecular clouds located in the southwest lobe of the CND. The data for the above mentioned molecules indicate 105 cm-3 ≲ n CND is tidally unstable. The derived chemical composition is compared with a chemical model calculated using the UCL_CHEM code that includes gas and grain reactions, and the effects of shock waves. Models are run for varying shock velocities, cosmic-ray ionization rates, and number densities. The resulting chemical composition is fitted best to an extremely high value of cosmic-ray ionization rate ζ ˜ 10-14 s-1, 3 orders of magnitude higher than the value in regular Galactic molecular clouds, if the pre-shock density is n=105 cm-3.

  11. Useful Method for the Preparation of Low-Coordinate Nickel(I) Complexes via Transformations of the Ni(I) Bis(amido) Complex K{Ni[N(SiMe3)(2,6- (i) Pr2-C6H3)]2}

    Lipschutz, Michael I; Tilley, T Don


    A convenient method of preparing two- and three-coordinate Ni(I) complexes of the form L-Ni(I)-X (L = P (t) Bu3, P (i) Pr3, DPPE, NHC; X = -N(SiMe3)(2,6- (i) Pr-C6H3), -O(2,6- (t) Bu2-4-Me-C6H2)) is reported. Protonation of the easily prepared anionic Ni(I) bis(amido) complex K{Ni[N(SiMe3)(2,6- (i) Pr-C6H3)]2} in the presence of an appropriate L-type ligand results in loss of HN(SiMe3)(2,6- (i) Pr-C6H3) and trapping of the resulting neutral Ni(I)-amido fragment to yield neutral, paramagnetic, two- and three-coordinate Ni(I) complexes. Protonation of these neutral amido complexes by the bulky phenol HO(2,6- (t) Bu2-4-Me-C6H2) results in loss of the second amido moiety and trapping by the resulting phenoxide to yield Ni(I)-O(2,6- (t) Bu2-4-Me-C6H2) complexes. The hapticity of the phenoxide ligand is influenced by the π-accepting ability of the L-type ligand. Where L = P (t) Bu3, a poor π-acceptor, the phenoxide acts as a π-acceptor and adopts a η(5)-bonding mode through dearomatization of the phenyl ring. When L = NHC, a competent π-acceptor, the phenoxide acts as a π-donor, adopting a η(1)-bonding mode through the O atom. The modular nature of this synthetic strategy allows variation of both the L- and X-type ligands of the complex in a stepwise fashion and should be extendable to a wide variety of ligand types for new Ni(I) complexes.

  12. Crystal structure of a compact three-dimensional metal–organic framework based on Cs+ and (4,5-di­cyano-1,2-phenyl­ene)bis­(phospho­nic acid)

    Mendes, Ricardo F.; Venkatramaiah, Nutalapati; Tomé, João P. C.; Almeida Paz, Filipe A.


    A new metal–organic framework compound, poly[[μ7-dihydrogen (4,5-di­cyano-1,2-phenyl­ene)diphospho­nato]­(oxonium)caesium], [Cs(C8H4N2O6P2)(H3O)]n (I), based on Cs+ and the organic linker 4,5-di­cyano-1,2-phenyl­ene)bis­(phospho­nic acid, (H4cpp), containing two distinct coordinating functional groups, has been prepared by a simple diffusion method and its crystal structure is reported. The coordination polymeric structure is based on a CsO8N2 complex unit comprising a monodentate hydro­nium cation, seven O-atom donors from two phospho­nium groups of the (H2cpp)2− ligand, and two N-atom donors from bridging cyano groups. The high level of connectivity from both the metal cation and the organic linker allow the formation of a compact and dense three-dimensional network without any crystallization solvent. Topologically (I) is a seven-connected uninodal network with an overall Schäfli symbol of {417.64}. Metal cations form an undulating inorganic layer, which is linked by strong and highly directional O—H⋯O hydrogen-bonding inter­actions. These metallic layers are, in turn, connected by the organic ligands along the [010] direction to form the overall three-dimensional framework structure. PMID:27980833

  13. Experimental investigation of the complete inner shell hydration energies of Ca2+: threshold collision-induced dissociation of Ca(2+)(H2O)x Complexes (x = 2-8).

    Carl, Damon R; Armentrout, P B


    The sequential bond energies of Ca(2+)(H(2)O)(x) complexes, where x = 1-8, are measured by threshold collision-induced dissociation (TCID) in a guided ion beam tandem mass spectrometer. From an electrospray ionization source that produces an initial distribution of Ca(2+)(H(2)O)(x) complexes where x = 6-8, complexes down to x = 2 are formed using an in-source fragmentation technique. Ca(2+)(H(2)O) cannot be formed in this source because charge separation into CaOH(+) and H(3)O(+) is a lower energy pathway than simple water loss from Ca(2+)(H(2)O)(2). The kinetic energy dependent cross sections for dissociation of Ca(2+)(H(2)O)(x) complexes, where x = 2-9, are examined over a wide energy range to monitor all dissociation products and are modeled to obtain 0 and 298 K binding energies. Analysis of both primary and secondary water molecule losses from each sized complex provides thermochemistry for the sequential hydration energies of Ca(2+) for x = 1-8 and the first experimental values for x = 1-4. Additionally, the thermodynamic onsets leading to the charge separation products from Ca(2+)(H(2)O)(2) and Ca(2+)(H(2)O)(3) are determined for the first time. Our experimental results for x = 1-6 agree well with previously calculated binding enthalpies as well as quantum chemical calculations performed here. Agreement for x = 1 is improved when the basis set on calcium includes core correlation.

  14. Threshold collision-induced dissociation of hydrated magnesium: experimental and theoretical investigation of the binding energies for Mg(2+)(H2O)x complexes (x=2-10).

    Carl, Damon R; Armentrout, Peter B


    The sequential bond energies of Mg(2+)(H2O)x complexes, in which x=2-10, are measured by threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. From an electrospray ionization source that produces an initial distribution of Mg(2+)(H2O)x complexes in which x=7-10, complexes down to x=3 are formed by using an in-source fragmentation technique. Complexes smaller than Mg(2+)(H2O)3 cannot be formed in this source because charge separation into MgOH(+)(H2O) and H3O(+) is a lower-energy pathway than simple water loss from Mg(2+)(H2O)3. The kinetic energy dependent cross sections for dissociation of Mg(2+)(H2O)x complexes, in which x=3-10, are examined over a wide energy range to monitor all dissociation products and are modeled to obtain 0 and 298 K binding energies. Analysis of both primary and secondary water molecule losses from each sized complex provides thermochemistry for the sequential hydration energies of Mg(2+) for x=2-10 and the first experimental values for x=2-4. Additionally, the thermodynamic onsets leading to the charge-separation products from Mg(2+)(H2O)3 and Mg(2+)(H2O)4 are determined for the first time. Our experimental results for x=3-7 agree well with quantum chemical calculations performed here and previously calculated binding enthalpies, as well as previous measurements for x=6. The present values for x=7-10 are slightly lower than previous experimental results and theory, but within experimental uncertainties.

  15. FTIR spectroscopy combined with quantum chemical calculations to investigate adsorbed nitrate on aluminium oxide surfaces in the presence and absence of co-adsorbed water.

    Baltrusaitis, Jonas; Schuttlefield, Jennifer; Jensen, Jan H; Grassian, Vicki H


    Surface reactions of nitrogen oxides with aluminium oxide particles result in the formation of adsorbed nitrate. Specifically, when alpha-Al(2)O(3) and gamma-Al(2)O(3) particles are exposed to gas-phase NO(2) and HNO(3) adsorbed nitrate forms on the surface. In this study, Fourier transform infrared (FTIR) spectroscopy is combined with quantum chemical calculations to further our understanding of the adsorbed nitrate product on aluminium oxide particle surfaces in the presence and absence of co-adsorbed water at 296 K. FTIR spectra of adsorbed nitrate on alpha-Al(2)O(3) and gamma-Al(2)O(3) particles are interpreted using calculated vibrational frequencies of nitrate coordinated to binuclear Al oxide cluster models. Comparison of the calculated and experimental vibrational frequencies of adsorbed nitrate establishes different modes of coordination (monodentate, bidentate and bridging) of the nitrate ion to the surface in the absence of adsorbed water. In the presence of co-adsorbed water, the nitrate ion becomes fully solvated, as shown by a comparison of the experimental nitrate infrared spectra as a function of relative humidity with the calculated nitrate vibrational frequencies for binuclear Al cluster compounds which contain both coordinated nitrate ions and water molecules. These calculations also suggest that adsorbed water can displace nitrate from direct coordination to the surface, leading to an outer-sphere nitrate adsorption complex as well as an inner-sphere complex. Furthermore, the relative humidity dependence of the spectra suggest that water does not evenly wet the surface even at high relative humidity, as there are open or bare surface sites where nitrate ions are not solvated. Besides adsorbed mondendate, bidendate, bridging and solvated nitrate, the presence of ion bound nitrate ion, partially solvated nitrate, molecular nitric acid, hydronium ion and H(3)O(+):NO(3)(-) ion pairs on the oxide surface are also discussed.

  16. Crystal structure of [NaZn(BTC)(H2O)4]·1.5H2O (BTC = benzene-1,3,5-tri-carb-oxy-l-ate): a heterometallic coordination compound.

    Ni, Min; Li, Quanle; Chen, Hao; Li, Shengqing


    The title coordination polymer, poly[[μ-aqua-tri-aqua-(μ3-benzene-1,3,5-tri-carboxyl-ato)sodiumzinc] sesquihydrate], {[NaZn(C9H3O6)(H2O)4]·1.5H2O} n , was obtained in ionic liquid microemulsion at room temperture by the reaction of benzene-1,3,5-tri-carb-oxy-lic acid (H3BTC) with Zn(NO3)2·6H2O in the presence of NaOH. The asymmetric unit comprises two Na(+) ions (each located on an inversion centre), one Zn(2+) ion, one BTC ligand, four coordinating water mol-ecules and two solvent water molecules, one of which is disordered about an inversion centre and shows half-occupation. The Zn(2+) cation is five-coordinated by two carboxyl-ate O atoms from two different BTC ligands and three coordinating H2O mol-ecules; the Zn-O bond lengths are in the range 1.975 (2)-2.058 (3) Å. The Na(+) cations are six-coordinated but have different arrangements of the ligands: one is bound to two carboxyl-ate O atoms of two BTC ligands and four O atoms from four coordinating H2O mol-ecules while the other is bound by four carboxyl-ate O atoms from four BTC linkers and two O atoms of coordinating H2O mol-ecules. The completely deprotonated BTC ligand acts as a bridging ligand binding the Zn(2+) atom and Na(+) ions, forming a layered structure extending parallel to (100). An intricate network of O-H⋯O hydrogen bonds is present within and between the layers.

  17. TOF MS Investigation of Nickel Oxide CVD

    Kondrateva, Anastasia S.; Mishin, Maxim V.; Alexandrov, Sergey E.


    NiO layers were deposited by metal-organic chemical vapor deposition using bis-(ethylcyclopentadienyl) nickel (EtCp)2Ni and oxygen or ozone. As a continuation of kinetic study of NiO MOCVD the gas-phase, transformations of (EtCp)2Ni were studied in the temperature range of 380-830 K. Time of reactions corresponding to the residence time of the gas stream in hot zone of the reactor was about 0.1 s under conditions studied. The interaction of (EtCp)2Ni with oxygen started at 450 K and its conversion rate reached the maximum at 700 K. The interaction of (EtCp)2Ni with ozone started at 400 K and its conversion rate reached the maximum at 600 K. Transformations of the gas phase with the temperature in the reaction zone were studied, the model reaction schemes illustrating (EtCp)2Ni transformations in the reaction systems containing oxygen and ozone have developed. In the reaction system (EtCp)2Ni-O2-Ar the main gas-phase products at 380-500 K were CO, CO2, HCO, C2H5OH, CpCOOH, and CpO. Formation of the C2H2O, C3H4O, and C5H8O was found at 630-830 K. The same gas-phase species, (C4H3O)2Ni and dialdehydes was formed in the reaction system (EtCp)2Ni-O3-O2-Ar. [Figure not available: see fulltext.

  18. Saturn Magnetospheric Impact on Surface Molecular Chemistry and Astrobiological Potential of Enceladus

    Cooper, P. D.; Cooper, J. F.; Sittler, E. C.; Burger, M. H.; Sturner, S. J.; Rymer, A. M.


    The active south polar surface of Enceladus is exposed to strong chemical processing by direct interaction with charged plasma and energetic particles in the local magnetospheric environment of this icy moon. Chemical oxidation activity is suggested by detection of H2O2 at the surface in this region and less directly by substantial presence of CO2, CO, and N2 in the plume gases. Molecular composition of the uppermost surface, including ejecta from plume activity, is radiolytically transformed mostly by penetrating energetic electrons with lesser effects from more depleted populations of energetic protons. The main sources of molecular plasma ions and E-ring dust grains in the magnetospheric environment are the cryovolcanic plume emissions from Enceladus. These molecular ions and the dust grains are chemically processed by magnetospheric interactions that further impact surface chemistry on return to Enceladus. For example, H2O neutrals dominating the emitted plume gas return to the surface mostly as H3O+ ions after magnetospheric processing. Surface oxidant loading is further increased by return of radiolytically processed ice grains from the E-ring. Plume frost deposition and micrometeoroid gardening protect some fraction of newly produced molecular species from destruction by further irradiation. The evident horizontal and vertical mobility of surface ices in the south polar region drive mixing of these processed materials into the moon interior with potential impacts on deep ice molecular chemistry and plume gas production. Similarly as suggested previously for Europa, the externally driven source of radiolytic oxidants could affect evolution of life in any subsurface liquid water environments of Enceladus.

  19. Exploring molecular changes at the surface of polypropylene after accelerated thermomolecular adhesion treatments.

    Awaja, Firas; Gilbert, Michael; Kelly, Georgina; Fox, Bronwyn; Brynolf, Russell; Pigram, Paul J


    A central composite rotatable design (CCRD) method was used to investigate the performance of the accelerated thermomolecular adhesion process (ATmaP), at different operating conditions. ATmaP is a modified flame-treatment process that features the injection of a coupling agent into the flame to impart a tailored molecular surface chemistry on the work piece. In this study, the surface properties of treated polypropylene were evaluated using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). All samples showed a significant increase in the relative concentration of oxygen (up to 12.2%) and nitrogen (up to 2.4%) at the surface in comparison with the untreated sample (0.7% oxygen and no detectable nitrogen) as measured by XPS. ToF-SIMS and principal components analysis (PCA) showed that ATmaP induced multiple reactions at the polypropylene surface such as chain scission, oxidation, nitration, condensation, and molecular loss, as indicated by changes in the relative intensities of the hydrocarbon (C(3)H(7)(+), C(3)H(5)(+), C(4)H(7)(+), and C(5)H(9)(+)), nitrogen and oxygen-containing secondary ions (C(2)H(3)O(+), C(3)H(8)N(+), C(2)H(5)NO(+), C(3)H(6)NO(+), and C(3)H(7)NO(+)). The increase in relative intensity of the nitrogen oxide ions (C(2)H(5)NO(+) and C(3)H(7)NO(+)) correlates with the process of incorporating oxides of nitrogen into the surface as a result of the injection of the ATmaP coupling agent.

  20. Copper-Based Metal-Organic Porous Materials for CO2 Electrocatalytic Reduction to Alcohols.

    Albo, Jonathan; Vallejo, Daniel; Beobide, Garikoitz; Castillo, Oscar; Castaño, Pedro; Irabien, Angel


    The electrocatalytic reduction of CO2 has been investigated using four Cu-based metal-organic porous materials supported on gas diffusion electrodes, namely, (1) HKUST-1 metal-organic framework (MOF), [Cu3 (μ6 -C9 H3 O6 )2 ]n ; (2) CuAdeAce MOF, [Cu3 (μ3 -C5 H4 N5 )2 ]n ; (3) CuDTA mesoporous metal-organic aerogel (MOA), [Cu(μ-C2 H2 N2 S2 )]n ; and (4) CuZnDTA MOA, [Cu0.6 Zn0.4 (μ-C2 H2 N2 S2 )]n . The electrodes show relatively high surface areas, accessibilities, and exposure of the Cu catalytic centers as well as favorable electrocatalytic CO2 reduction performance, that is, they have a high efficiency for the production of methanol and ethanol in the liquid phase. The maximum cumulative Faradaic efficiencies for CO2 conversion at HKUST-1-, CuAdeAce-, CuDTA-, and CuZnDTA-based electrodes are 15.9, 1.2, 6, and 9.9 %, respectively, at a current density of 10 mA cm(-2) , an electrolyte-flow/area ratio of 3 mL min cm(-2) , and a gas-flow/area ratio of 20 mL min cm(-2) . We can correlate these observations with the structural features of the electrodes. Furthermore, HKUST-1- and CuZnDTA-based electrodes show stable electrocatalytic performance for 17 and 12 h, respectively. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Modeling the ion abundances in Saturn's inner magnetosphere

    Fleshman, B. L.; Bagenal, F.; Delamere, P. A.


    Water ejected from Enceladus's plumes provides much of the material that fills both the dense H2O torus centered on Enceladus's orbit, as well as Saturn's neutral clouds which extend at least four times farther from Saturn. Photo- and impact ionization transforms a few percent of these neutrals into the ions co-rotating with Saturn's magnetosphere, and charge exchange is responsible for a substantial redistribution among the hydrogen and water-group ions, though it does not alter the overall plasma density. In this paper, we explore ion abundances at Saturn with a chemistry model developed to include all of these processes. Building on our earlier attempts, we now include a source of neutrals from a neutral cloud model, so as to advance our description to include radial and latitudinal variations. At the same time, we now prescribe a radially-varying plasma diffusion coefficient to study the magnetosphere's inability to contain centrifigually-unstable plasma. We also are interested in the effect of hot electrons (102-103 eV) beamed along field lines into the equatorial region chiefly of interest. Our parameter study of radial diffusion and hot-electron flux is anchored to available Cassini CAPS water-group and proton abundances. Preliminary results suggest an injection of ~10 MW by hot electrons, and reveal promising radial trends in the water-group abundances that agree well with Sittler et al. (2008). We can also simulate an Enceladus torus dominated H3O+ -- a result not obtainable prior to coupling the chemistry and neutral cloud models.

  2. The Effect of Broadband Soft X-Rays in SO2-Containing Ices: Implications on the Photochemistry of Ices toward Young Stellar Objects

    Pilling, S.; Bergantini, A.


    We investigate the effects produced mainly by broadband soft X-rays up to 2 keV (plus fast (˜keV) photoelectrons and low-energy (˜eV) induced secondary electrons) in the ice mixtures containing H2O:CO2:NH3:SO2 (10:1:1:1) at two different temperatures (50 and 90 K). The experiments are an attempt to simulate the photochemical processes induced by energetic photons in SO2-containing ices present in cold environments in the ices surrounding young stellar objects (YSO) and in molecular clouds in the vicinity of star-forming regions, which are largely illuminated by soft X-rays. The measurements were performed using a high-vacuum portable chamber from the Laboratório de Astroquímica e Astrobiologia (LASA/UNIVAP) coupled to the spherical grating monochromator beamline at the Brazilian Synchrotron Light Source (LNLS) in Campinas, Brazil. In situ analyses were performed by a Fourier transform infrared spectrometer. Sample processing revealed the formation of several organic molecules, including nitriles, acids, and other compounds such as H2O2, H3O+, SO3, CO, and OCN-. The dissociation cross section of parental species was on the order of (2-7) × 10-18 cm2. The ice temperature does not seem to affect the stability of SO2 in the presence of X-rays. Formation cross sections of new species produced were also determined. Molecular half-lives at ices toward YSOs due to the presence of incoming soft X-rays were estimated. The low values obtained employing two different models of the radiation field of YSOs (TW Hydra and typical T-Tauri star) reinforce that soft X-rays are indeed a very efficient source of molecular dissociation in such environments.

  3. Molecular co-crystals of 2-aminothiazole derivatives.

    Lynch; Nicholls; Smith; Byriel; Kennard


    A series of molecular adducts of 2-aminothiazole derivatives - 2-aminothiazole, 2-amino-2-thiazoline and 2-aminobenzothiazole with the carboxylic-acid-substituted heterocyclics indole-2-carboxylic acid, N-methylpyrrole-2-carboxylic acid and thiophene-2-carboxylic acid - have been prepared and characterized using X-ray powder diffraction and in five cases by single-crystal X-ray diffraction methods. These five compounds are the adducts of 2-amino-2-thiazolium with indole-2-carboxylate [(C(3)H(7)N(2)S)(+)(C(9)H(6)NO(2))(-)], and N-methylpyrrole-2-carboxylate [(C(3)H(7)N(2)S)(+)-(C(6)H(6)NO(2))(-)], 2-aminobenzothiazolium with indole-2-carboxylate [(C(7)H(7)N(2)S)(+)(C(9)H(6)NO(2))(-)], N-methylpyrrole-2-carboxylate [(C(7)H(7)N(2)S)(+)(C(6)H(6)NO(2))(-)] and thiophene-2-carboxylate [(C(7)H(7)N(2)S)(+)(C(5)H(3)O(2)S)(-)]. All complexes involve proton transfer, as indicated by IR spectroscopy, while the five crystal structures display similar hydrogen-bonding patterns with the dominant interaction being an R(2)(2)(8) graph set dimer association between carboxylate groups and the amine/heterocyclic nitrogen sites. Futhermore, in each case a subsiduary interaction between an amino proton and a carboxylate oxygen completes a linear hydrogen-bonded chain. In addition to this, the indole-2-carboxylate molecules in the adduct structure with 2-amino-2-thiazolium form associated dimers which add to the hydrogen-bonding network.

  4. Quantification of methane in humid air and exhaled breath using selected ion flow tube mass spectrometry.

    Dryahina, Kseniya; Smith, D; Spanel, P


    In selected ion flow tube mass spectrometry, SIFT-MS, analyses of humid air and breath, it is essential to consider and account for the influence of water vapour in the media, which can be profound for the analysis of some compounds, including H(2)CO, H(2)S and notably CO(2). To date, the analysis of methane has not been considered, since it is known to be unreactive with H(3)O(+) and NO(+), the most important precursor ions for SIFT-MS analyses, and it reacts only slowly with the other available precursor ion, O(2) (+). However, we have now experimentally investigated methane analysis and report that it can be quantified in both air and exhaled breath by exploiting the slow O(2) (+)/CH(4) reaction that produces CH(3)O(2) (+) ions. We show that the ion chemistry is significantly influenced by the presence of water vapour in the sample, which must be quantified if accurate analyses are to be performed. Thus, we have carried out a study of the loss rate of the CH(3)O(2) (+) analytical ion as a function of sample humidity and deduced an appropriate kinetics library entry that provides an accurate analysis of methane in air and breath by SIFT-MS. However, the associated limit of detection is rather high, at 0.2 parts-per-million, ppm. We then measured the methane levels, together with acetone levels, in the exhaled breath of 75 volunteers, all within a period of 3 h, which shows the remarkable sample throughput rate possible with SIFT-MS. The mean methane level in ambient air is seen to be 2 ppm with little spread and that in exhaled breath is 6 ppm, ranging from near-ambient levels to 30 ppm, with no significant variation with age and gender. Methane can now be included in the wide ranging analyses of exhaled breath that are currently being carried out using SIFT-MS.

  5. Water-assisted proton transfer in ferredoxin I.

    Lutz, Stephan; Tubert-Brohman, Ivan; Yang, Yonggang; Meuwly, Markus


    The role of water molecules in assisting proton transfer (PT) is investigated for the proton-pumping protein ferredoxin I (FdI) from Azotobacter vinelandii. It was shown previously that individual water molecules can stabilize between Asp(15) and the buried [3Fe-4S](0) cluster and thus can potentially act as a proton relay in transferring H(+) from the protein to the μ(2) sulfur atom. Here, we generalize molecular mechanics with proton transfer to studying proton transfer reactions in the condensed phase. Both umbrella sampling simulations and electronic structure calculations suggest that the PT Asp(15)-COOH + H(2)O + [3Fe-4S](0) → Asp(15)-COO(-) + H(2)O + [3Fe-4S](0) H(+) is concerted, and no stable intermediate hydronium ion (H(3)O(+)) is expected. The free energy difference of 11.7 kcal/mol for the forward reaction is in good agreement with the experimental value (13.3 kcal/mol). For the reverse reaction (Asp(15)-COO(-) + H(2)O + [3Fe-4S](0)H(+) → Asp(15)-COOH + H(2)O + [3Fe-4S](0)), a larger barrier than for the forward reaction is correctly predicted, but it is quantitatively overestimated (23.1 kcal/mol from simulations versus 14.1 from experiment). Possible reasons for this discrepancy are discussed. Compared with the water-assisted process (ΔE ≈ 10 kcal/mol), water-unassisted proton transfer yields a considerably higher barrier of ΔE ≈ 35 kcal/mol.

  6. VOC Composition of Air Masses Transported from Asia to the U.S. West Coast

    de Gouw, J.; Warneke, C.; Kuster, B.; Parrish, D.; Holloway, J.; Huebler, G.; Fehsenfeld, F.


    Airborne measurements of volatile organic compounds (VOCs) were performed using a proton-transfer-reaction mass spectrometer (PTR-MS) operated onboard a NOAA WP-3 aircraft during the Intercontinental Transport and Chemical Transformation (ITCT) experiment in 2002. Enhancements of acetone (CH3COCH3), methanol (CH3OH), acetonitrile (CH3CN) and in some cases benzene were observed in air masses that were impacted by outflow from Asia. The enhancement ratios with respect to carbon monoxide are compared to emission factors for fossil fuel combustion and biomass burning, which gives some insight into the sources responsible for the pollution. The observed mixing ratios for acetone, methanol and in particular acetonitrile were generally reduced in the marine boundary layer, suggesting the presence of an ocean uptake sink. The ocean uptake of acetonitrile was found to be particularly efficient in a zone with upwelling water off of the U.S. west coast. Reduced mixing ratios of acetone and methanol were observed in a stratospheric intrusion. This observation gives some information about the lifetime of these VOCs in the stratosphere. Enhanced concentrations of aromatic hydrocarbons were observed in air masses that were impacted by urban sources in California. The ratio between the concentrations of benzene, toluene and higher aromatics indicated the degree of photochemical oxidation. PTR-MS only gives information about the mass of the ions produced by proton-transfer reactions between H3O+ and VOCs in the instrument. The identification of VOCs was confirmed by coupling a gas-chromatographic (GC) column to the instrument and post-flight GC-PTR-MS analyses of canister samples collected during the flights.

  7. Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates.

    Liang, Xinjin; Csetenyi, Laszlo; Gadd, Geoffrey Michael


    In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa(+)·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe(++)(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

  8. A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

    Robin A. Cox


    Full Text Available If a species does not have a finite lifetime in the reaction medium, it cannot be a mechanistic intermediate. This principle was first enunciated by Jencks, as the concept of an enforced mechanism. For instance, neither primary nor secondary carbocations have long enough lifetimes to exist in an aqueous medium, so SN1 reactions involving these substrates are not possible, and an SN2 mechanism is enforced. Only tertiary carbocations and those stabilized by resonance (benzyl cations, acylium ions are stable enough to be reaction intermediates. More importantly, it is now known that neither H3O+ nor HO– exist as such in dilute aqueous solution. Several recent high-level calculations on large proton clusters are unable to localize the positive charge; it is found to be simply “on the cluster” as a whole. The lifetime of any ionized water species is exceedingly short, a few molecular vibrations at most; the best experimental study, using modern IR instrumentation, has the most probable hydrated proton structure as H13O6+, but only an estimated quarter of the protons are present even in this form at any given instant. Thanks to the Grotthuss mechanism of chain transfer along hydrogen bonds, in reality a proton or a hydroxide ion is simply instantly available anywhere it is needed for reaction. Important mechanistic consequences result. Any charged oxygen species (e.g., a tetrahedral intermediate is also not going to exist long enough to be a reaction intermediate, unless the charge is stabilized in some way, usually by resonance. General acid catalysis is the rule in reactions in concentrated aqueous acids. The Grotthuss mechanism also means that reactions involving neutral water are favored; the solvent is already highly structured, so the entropy involved in bringing several solvent molecules to the reaction center is unimportant. Examples are given.

  9. Formation of the organic-inorganic proton exchange membrane

    A.O. Maizelis


    Full Text Available The use of electrolyzers for the low-temperature water electrolysis with the solid polymer membrane is perspective for production of hydrogen using renewable energy sources. However, the high cost of membrane materials obstructs the mass commissioning of such electrolyzers. Most of the researches devoted to the technologies of membranes formation, alternative to Nafion®, deal only with organic materials. Aim: The aim of this research is to develop the method for formation of the competitive proton exchange membrane based on polyvinyl alcohol (PVA and inorganic hydrates. Materials and Methods: The hydrated oxide of tin was added to the 2...10% PVA solution, mixed and applied to inert base layer by layer for formation of the membrane. Then the membrane was separated from the base. The reinforcing mesh was used to improve mechanical properties of the membrane. The hydrated tin oxide was prepared by reaction of tin chloride and ammonium hydroxide solutions. Results: The conditions of formation of proton-exchange membranes based on polyvinyl alcohol and hydrated oxide of tin were investigated. The series of membranes containing 30, 50, 70, 80 and 90% of hydrated tin oxide are obtained. It is shown that a solid membrane film with the thickness over 100 μm can be obtained if the content of PVA exceeds 30%. It is shown that it is necessary to crosslink the chains of PVA in the resulting film. The structure of the obtained proton exchange membrane consists of PVA chains crosslinked by aldehyde, between which the globules of hydrated tin oxide are situated. The membrane conductivity is provided by both proton mobility of hydroxyl group of PVA and H3O+/H2O and OH–/H2O groups that are formed due to the partial dissociation of hydrated oxide on the surface of the globules.

  10. Observation and Simulation of Ion Flow Stagnation in the Enceladus Plume

    Tokar, R. L.; Omidi, N.; Averkamp, T.; Wang, Z.; Gurnett, D. A.; Thomsen, M. F.; Crary, F. J.


    The Cassini Plasma Spectrometer (CAPS) detected freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier charged water clusters (HxO2)+ very close to Enceladus within and outside of the south polar plume, see (1). The data were obtained during close flybys of Enceladus in 2008 and 2009 (E3, E5, E7) when CAPS viewing of the ion plasma was favorable. The ions are observed in CAPS detectors looking in the Cassini ram direction and close to the ram kinetic energy, indicative of a nearly stagnant (at rest with respect to Enceladus) plasma flow in the plume. In this study these CAPS observations are compared with 3D hybrid simulations of the Enceladus interaction (2). The primary goal is to simulate the spatial extent of the ion flow stagnation in and near the plume observed by CAPS. The simulations include not only plume water vapor undergoing charge exchange with the ambient ion flow but also heavy plume dust that acquires a negative charge. The neutral dust spatial distribution is modeled using particle impact rates obtained from Radio and Plasma Wave System (RPWS) data while plasma fluid parameters during the encounters are obtained from CAPS. The dust is a second heavy particle component in the simulation that is followed in the same manner as the positive ions. The dust absorption of electrons mass-loads the plasma producing flow deceleration observable by CAPS over the high impact regions measured by RPWS. This deceleration is compared with that due to the charge exchange process. 1.)Tokar,R.L. et al. Geophys. Res. Lett., 36, L13203, doi:10.1029/2009GL038923, 2009. 2.)Omidi,N. et al., J. Geophys. Res., 115, A05212, doi:10.1029/2009JA014391, 2010.

  11. Universal reaction mechanism of boronic acids with diols in aqueous solution: kinetics and the basic concept of a conditional formation constant.

    Furikado, Yuki; Nagahata, Tomomi; Okamoto, Takuya; Sugaya, Tomoaki; Iwatsuki, Satoshi; Inamo, Masahiko; Takagi, Hideo D; Odani, Akira; Ishihara, Koji


    To establish a detailed reaction mechanism for the condensation between a boronic acid, RB(OH)2, and a diol, H2L, in aqueous solution, the acid dissociation constants (Ka(BL)) of boronic acid diol esters (HBLs) were determined based on the well-established concept of conditional formation constants of metal complexes. The pKa values of HBLs were 2.30, 2.77, and 2.00 for the reaction systems, 2,4-difluorophenylboronic acid and chromotropic acid, 3-nitrophenylboronic acid and alizarin red S, and phenylboronic acid and alizarin red S, respectively. A general and precise reaction mechanism of RB(OH)2 with H2L in aqueous solution, which can serve as a universal reaction mechanism for RB(OH)2 and H2L, was proposed on the basis of (a) the relative kinetic reactivities of the RB(OH)2 and its conjugate base, that is, the boronate ion, toward H2L, and (b) the determined pKa values of HBLs. The use of the conditional formation constant, K', based on the main reaction: RB(OH)2 + H2L (K1)⇌ RB(L)(OH)(-) + H3O(+) instead of the binding constant has been proposed for the general reaction of uncomplexed boronic acid species (B') with uncomplexed diol species (L') to form boronic acid diol complex species (esters, BL') in aqueous solution at pH 5-11: B' + L' (K')⇌ BL'. The proposed reaction mechanism explains perfectly the formation of boronic acid diol ester in aqueous solution. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Prevention of Renal Injury After Induction of Ozone Tolerance in Rats Submitted to Warm Ischaemia

    E. Barber


    Full Text Available On the basis that ozone (O3 can upregulate cellular antioxidant enzymes, a morphological, biochemical and functional renal study was performed in rats undergoing a prolonged treatment with O3 before renal ischaemia. Rats were divided into four groups: (1 control, a medial abdominal incision was performed to expose the kidneys; (2 ischaemia, in animals undergoing a bilateral renal ischaemia (30 min, with subsequent reperfusion (3 h; (3 O3 + ischaemia, as group 2, but with previous treatment with O3 (0.5 mg/kg per day given in 2.5 ml O2 via rectal administration for 15 treatments; (4 O2 + ischaemia, as group 3, but using oxygen (O2 alone. Biochemical parameters as fructosamine level, phospholipase A, and superoxide dismutases (SOD activities, as well as renal plasma flow (RPF and glomerular filtration rate (GFR, were measured by means of plasma clearance of p-amino-hippurate and inulin, respectively. In comparison with groups 1 and 3, the RPF and GFR were significantly decreased in groups 2 and 4. Interestingly, renal homogenates of the latter groups yielded significantly higher values of phospholipase A activity and fructosamine level in comparison with either the control (1 and the O3 (3 treated groups. Moreover renal SOD activity showed a significant increase in group 3 without significant differences among groups 1, 2 and 4. Morphological alterations of the kidney were present in 100%, 88% and 30% of the animals in groups 2, 4 and 3, respectively. It is proposed that the O3 protective effect can be ascribed to the substantial possibility of upregulating the antioxidant defence system capable of counteracting the damaging effect of ischaemia. These findings suggest that, whenever possible, ozone preconditioning may represent a prophylactic approach for minimizing renal damage before transplantation.

  13. Construction of three metal-organic frameworks based on multifunctional T-shaped tripodal ligands, H3PyImDC

    Jing, Xuemin


    Three novel metal-organic frameworks (MOFs), |(C3H 7NO)2(H2O)|[Zn3(C10H 5N3O4)3(C3H 7NO)2] (1), |(H2O)5(H 3O)(NO3)|[Nd2(C10H5N 3O4)3(H2O)4] (2), and |(H2O)2|[Nd3(C10H5N 3O4)3(C10H4N 3O4)] (3), based on the T-shaped tripodal ligands 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic acid and 2-(pyridine-3-yl)-1H-4, 5-imidazoledicarboxylic acid (H3PyImDC), have been constructed under solvo-/hydrothermal conditions. The diverse coordination modes of H 3PyImDC ligands have afforded the assembly of three novel compounds. In compound 1, two oxygen atoms and three nitrogen atoms of the H 3PyImDC ligand, a T-shaped linker, coordinate to two zinc centers to form a novel bbm net with two distinct channels along the [100] and [001] directions. In compound 2, H3PyImDC ligands coordinate to neodymium centers to form a ladder-like chain which then interacts with a water molecules chain via hydrogen-bondings to construct a 3D supermolecular structure. In compound 3, H3PyImDC ligands, a T-shaped linker, coordinate to neodymium centers to form a (3,6)-connected net with an ant topology. In compounds 1-3, the two H3PyImDC ligands exhibit different coordination modes with zinc and neodymium centers, which afforded the expected structural diversity. Additionally, all three compounds exhibit strong fluorescence emissions in the solid state at room temperature. © 2010 American Chemical Society.

  14. A DFT and structural investigation of the conformations of Fischer carbene complexes

    Landman, Marilé


    A set of different Fischer carbene complexes of group VI and VII metals, with varied heteroatom and heteroaromatic substituents on the carbene carbon atom, was studied. Density functional theory as well as single crystal diffraction techniques were employed to investigated the most stable conformation of these complexes. The complexes studied, [M(CO)4L{C(X)Z}], with L = PPh3 or CO, X = ethoxy (-OCH2CH3) or amino (-NH2 or NHCy) substituents as the heteroatom carbene substituents, Z = 2-furyl (-C4H3O), 2-thienyl (-C4H3S), 2-(N-methyl)pyrrolyl (-C4H3NCH3) as the second carbene substituent had their substituents varied systematically to give all the possible conformations of these complexes. The conformations of the complexes, in particular the relative orientations of the heteroatoms in the molecule (syn vs. anti), E/Z isomerism in the aminocarbene complexes and cis/trans isomerism in the ligand substituted complexes as well as various combinations of these aspects, were studied. In general, it was found that the most stable conformation theoretically as well as in the solid state for most of the complexes preferred the syn conformation. The Z-isomer is generally preferred over the E isomer while the cis is more predominant than the trans isomer. Using DFT and NBO calculations, explanations for the preferred conformations were explored. It was concluded that both steric and electronic factors influence the conformations of the carbene complexes, with the extent of contribution of these two factors varying for each of the different carbene substituents.

  15. Composición química del agua de lluvia y de niebla recolectada en la reserva biológica Monteverde

    Tatiana Vásquez Morera


    Full Text Available Se determinó la composición química del agua de lluvia y de niebla en tres sitios en la Reserva Biológica Monteverde, Puntarenas; entre octubre 2009 y enero 2010. Debido a su estado de conservación y a su ubicación geográfica sobre la deriva continental, la Reserva Biológica Monteverde ofrece un sitio de estudio ideal, para el estudio de la composición de las aguas atmosféricas (agua de lluvia y de niebla. Las muestras de agua de niebla se recolectaron al utilizar muestreadores de niebla con líneas de teflón, mientras que las de agua de lluvia se recogieron al emplear muestreadores de lluvia simples y uno de cascada. En ambos tipos de agua se analizaron las especies iónicas más relevantes: H3O+, NH4 +, Ca2+, Mg2+, K+, Na+, Cl-, NO3 - y SO4 2-, al utilizar cromatografía de iones y detección por conductividad eléctrica. Las concentraciones promedio de estas especies en el agua de lluvia estuvieron entre 0,54 ± 0,02 μeq L-1 y 101± 3 μeq L-1, mientras que en el agua de niebla variaron entre 1,00 ± 0,02 μeq L-1 y 93 ± 4 μeq L-1. Además, se presentan el balance iónico y los factores de enriquecimiento con respecto al mar y el suelo de ambos tipos de muestras.

  16. Biomass pyrolysis: thermal decomposition mechanisms of furfural and benzaldehyde.

    Vasiliou, AnGayle K; Kim, Jong Hyun; Ormond, Thomas K; Piech, Krzysztof M; Urness, Kimberly N; Scheer, Adam M; Robichaud, David J; Mukarakate, Calvin; Nimlos, Mark R; Daily, John W; Guan, Qi; Carstensen, Hans-Heinrich; Ellison, G Barney


    The thermal decompositions of furfural and benzaldehyde have been studied in a heated microtubular flow reactor. The pyrolysis experiments were carried out by passing a dilute mixture of the aromatic aldehydes (roughly 0.1%-1%) entrained in a stream of buffer gas (either He or Ar) through a pulsed, heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 75-150 Torr with the SiC tube wall temperature in the range of 1200-1800 K. Characteristic residence times in the reactor are 100-200 μsec after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 μTorr. Products were detected using matrix infrared absorption spectroscopy, 118.2 nm (10.487 eV) photoionization mass spectroscopy and resonance enhanced multiphoton ionization. The initial steps in the thermal decomposition of furfural and benzaldehyde have been identified. Furfural undergoes unimolecular decomposition to furan + CO: C4H3O-CHO (+ M) → CO + C4H4O. Sequential decomposition of furan leads to the production of HC≡CH, CH2CO, CH3C≡CH, CO, HCCCH2, and H atoms. In contrast, benzaldehyde resists decomposition until higher temperatures when it fragments to phenyl radical plus H atoms and CO: C6H5CHO (+ M) → C6H5CO + H → C6H5 + CO + H. The H atoms trigger a chain reaction by attacking C6H5CHO: H + C6H5CHO → [C6H6CHO]* → C6H6 + CO + H. The net result is the decomposition of benzaldehyde to produce benzene and CO.

  17. Electron Paramagnetic Resonance: Elementary Theory and Practical Applications, Second Edition (John A. Weil and James R. Bolton)

    Williams, Ffrancon


    some of the difficulties regarding the use of EPR in studying the OH and hydrated electron (e aq - ) intermediates generated in liquid water by high energy radiation. The problems of detecting the OH radical due to its high reactivity and g-tensor anisotropy are well known and duly noted, but perhaps more striking is the fact that the EPR characterization of e aq - still remains uncertain even after more than 40 years of study. However, in suggesting the possibility that the uninformative singlet EPR spectrum assigned to e aq - could well be coming from the neutral hydronium (H 3 O) radical, the authors make the surprising assertion that the latter would be a π-type radical. In fact, H 3 O with its 9 valence electrons is a hypervalent radical and can be represented as an excess electron bound to a closed-shell H 3 O + structure, such that the unpaired electron occupies a Rydberg 3s-type orbital rather than a 2p-orbital on oxygen. This description is confirmed by high-level theoretical calculations (4, 5 ) which also indicate that H 3 O would only have marginal stability, its dissociation into a hydrogen atom and H 2 O being exothermic with an estimated barrier (0.004 eV) that is much less than kT at room temperature (0.026 eV). On the other hand, the e aq - species is relatively stable in purified water at pH 8 and quite long lived ( t 1/2 = 500 µs) with respect to its transformation to the hydrogen atom (6) . Moreover, e aq - has been shown to possess a unit negative charge (7) , so its assignment to H 3 O or even a solvated H 3 O (8 ) must be regarded as extremely questionable. Chapters 4 and 5 deal with the basic anisotropic Zeeman energy (g) and hyperfine (A) interactions that must be considered in the analysis of solid-state EPR spectra. Although these chapters are again much the same as in the earlier editions, Section 4.9, Comparative Overview, has been added and briefly discusses the pros and cons surrounding the methodology and information derived from

  18. 不同铁源对吉富罗非鱼生长及表观消化率的影响%Effects of different iron sources on the growth of and apparent digestibility Oreochromis niloticus

    王进; 刘恒见; 黄峰; 韩金林


    为观察不同铁源对吉富罗非鱼( Oreochromis niloticus)生长及表观消化率的影响,试验以初重6.79 g左右的吉富罗非鱼为饲养对象,采用酪蛋白、糊精为主要原料制成半精制日粮,分别添加铁含量相等(100 mg/kg饲料)的硫酸亚铁、氯化铁、氯化亚铁、柠檬酸亚铁、卟啉铁,饲喂吉富罗非鱼70 d。结果显示,在铁含量相等(100 mg/kg饲料)的半精制日粮中添加氯化亚铁,吉富罗非鱼的增重率显著( P<0.05)高于其它四种铁源。以增重率为指标,吉富罗非鱼日粮中适宜以氯化亚铁作为添加铁源。%In order to study the effects of diets with different iron sources on the growth performance and apparent digesti -bility in Oreochromis niloticus, the O.niloticus with approximate initial weight of 6.79 g were fed with daily diets varied of 5 iron sources for 70 days under water circulating system .The daily diets were mainly formulating by casein and dextrin with the same Fe amount level (100 mg/kg) from different iron sources, ferrisulphas (FeSO4· 7H2O), ferric chloride (FeCl3· 6H2O), ferrous chloride (FeCl2· 4H2O), ferrous citrate(Fe3(C6H3O7)2· 6H2O) and ferroporphyrin (C34H32 ClFeN4O4) respectively.The results indicated that the weight gain rate (WGR) of O.niloticus fed under the daily diet with ferrous chloride was significantly higher than that under the other four groups (P<0.05).Considered WGR as a mainly indicator , the ferrous chloride should be the most suitable iron source added to daily diet for O.niloticus.

  19. Airborne Trace Gas and Aerosol Measurements in Several Shale Gas Basins during the SONGNEX (Shale Oil and Natural Gas Nexus) Campaign 2015

    Warneke, C.; Trainer, M.; De Gouw, J. A.


    Oil and natural gas from tight sand and shale formations has increased strongly over the last decade. This increased production has been associated with emissions of methane, non-methane hydrocarbons and other trace gases to the atmosphere, which are concerns for air quality, climate and air toxics. The NOAA Shale Oil and Natural Gas Nexus (SONGNEX) aircraft campaign took place in 2015, when the NOAA WP-3 aircraft conducted 20 research flights between March 19 and April 27, 2015 in the following shale gas regions: Denver-Julesberg, Uintah, Upper Green River, San Juan, Bakken, Barnett, Eagle Ford, Haynesville, Woodford, and Permian. The NOAA P3 was equipped with an extensive set of gas phase measurements, including instruments for methane, ethane, CO, CO2, a new H3O+CIMS, canister and cartridge samples for VOCs, HCHO, glyoxal, HNO3, NH3, NOx, NOy, PANs, ozone, and SO2. Aerosol number and size distributions were also measured. This presentation will focus on an overview of all the measurements onboard the NOAA WP-3 aircraft and discuss the differences between the shale gas regions. Due to a drop in oil prices, drilling for oil decreased in the months prior to the mission, but nevertheless the production of oil and natural gas were near the all-time high. Many of the shale gas basins investigated during SONGNEX have quite different characteristics. For example, the Permian Basin is a well-established field, whereas the Eagle Ford and the Bakken saw an almost exponential increase in production over the last few years. The basins differ by the relative amounts of natural gas versus oil that is being produced. Previous work had shown a large variability in methane emissions relative to the production (leak rate) between different basins. By including more and qualitatively different basins during SONGNEX, the study has provided an extensive data set to address how emissions depend on raw gas composition, extraction techniques and regulation. The influence of these

  20. An Improved, Automated Whole-Air Sampler and VOC Analysis System: Results from SONGNEX 2015

    Lerner, B. M.; Gilman, J.; Tokarek, T. W.; Peischl, J.; Koss, A.; Yuan, B.; Warneke, C.; Isaacman-VanWertz, G. A.; Sueper, D.; De Gouw, J. A.; Aikin, K. C.


    oxygenated species (alcohols and ketones) and cycloalkanes. We present an intercomparison of the GC-MS analysis system and iWAS samples from SONGNEX with a new H3O+ CIMS-TOF and a spectroscopic ethane measurement that also flew aboard the NOAA WP-3D aircraft during SONGNEX. We also consider the effect of sample age on observed mixing ratio.

  1. The ToF-ACSM: a portable aerosol chemical speciation monitor with TOFMS detection

    R. Fröhlich


    Full Text Available We present a new instrument for monitoring aerosol composition, the time-of-flight aerosol chemical speciation monitor (ToF-ACSM, combining precision state-of-the-art time-of-flight mass spectrometry with stability, reliability, and easy handling, which are necessities for long-term monitoring operations on the scale of months to years. Based on Aerodyne aerosol mass spectrometer (AMS technology, the ToF-ACSM provides continuous online measurements of chemical composition and mass of non-refractory submicron aerosol particles. In contrast to the larger AMS, the compact-sized and lower-priced ToF-ACSM does not feature particle sizing, similar to the widely-used quadrupole-ACSM (Q-ACSM. Compared to the Q-ACSM, the ToF-ACSM features a better mass resolution of M/ΔM = 600 and better detection limits on the order of −3 for a time resolution of 30 min. With simple upgrades these limits can be brought down by another factor of ~ 8. This allows for operation at higher time resolutions and in low concentration environments. The associated software packages (single packages for integrated operation and calibration and analysis provide a high degree of automation and remote access, minimising the need for trained personnel on site. Intercomparisons with Q-ACSM, C-ToF-AMS, nephelometer and scanning mobility particle sizer (SMPS measurements, performed during a first long-term deployment (> 10 months on the Jungfraujoch mountain ridge (3580 m a.s.l. in the Swiss Alps, agree quantitatively. Additionally, the mass resolution of the ToF-ACSM is sufficient for basic mass defect resolved peak fitting of the recorded spectra, providing a data stream not accessible to the Q-ACSM. This allows for quantification of certain hydrocarbon and oxygenated fragments (e.g. C3H7+ and C2H3O+, both occurring at m/Q = 43 Th, as well as improving inorganic/organic separation.

  2. Detection of formaldehyde emissions from an industrial zone in the Yangtze River Delta region of China using a proton transfer reaction ion-drift chemical ionization mass spectrometer

    Ma, Yan; Diao, Yiwei; Zhang, Bingjie; Wang, Weiwei; Ren, Xinrong; Yang, Dongsen; Wang, Ming; Shi, Xiaowen; Zheng, Jun


    A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an industrial zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydrazone (DNPH) cartridges and the results showed fairly good agreement (slope = 0.81, R2 = 0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9-2.4 (RH = 1-81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation

  3. Transport properties investigation of aqueous protic ionic liquid solutions through conductivity, viscosity, and NMR self-diffusion measurements.

    Anouti, Mérièm; Jacquemin, Johan; Porion, Patrice


    We present a study on the transport properties through conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], η, σ, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K.

  4. Arsenic-rich acid mine water with extreme arsenic concentration: mineralogy, geochemistry, microbiology, and environmental implications.

    Majzlan, Juraj; Plášil, Jakub; Škoda, Radek; Gescher, Johannes; Kögler, Felix; Rusznyak, Anna; Küsel, Kirsten; Neu, Thomas R; Mangold, Stefan; Rothe, Jörg


    Extremely arsenic-rich acid mine waters have developed by weathering of native arsenic in a sulfide-poor environment on the 10th level of the Svornost mine in Jáchymov (Czech Republic). Arsenic rapidly oxidizes to arsenolite (As2O3), and there are droplets of liquid on the arsenolite crust with high As concentration (80,000-130,000 mg·L(-1)), pH close to 0, and density of 1.65 g·cm(-1). According to the X-ray absorption spectroscopy on the frozen droplets, most of the arsenic is As(III) and iron is fully oxidized to Fe(III). The EXAFS spectra on the As K edge can be interpreted in terms of arsenic polymerization in the aqueous solution. The secondary mineral that precipitates in the droplets is kaatialaite [Fe(3+)(H2AsO4)3·5H2O]. Other unusual minerals associated with the arsenic lens are běhounekite [U(4+)(SO4)2·4H2O], štěpite [U(4+)(AsO3OH)2·4H2O], vysokýite [U(4+)[AsO2(OH)2]4·4H2O], and an unnamed phase (H3O)(+)2(UO2)2(AsO4)2·nH2O. The extremely low cell densities and low microbial biomass have led to insufficient amounts of DNA for downstream polymerase chain reaction amplification and clone library construction. We were able to isolate microorganisms on oligotrophic media with pH ∼ 1.5 supplemented with up to 30 mM As(III). These microorganisms were adapted to highly oligotrophic conditions which disabled long-term culturing under laboratory conditions. The extreme conditions make this environment unfavorable for intensive microbial colonization, but our first results show that certain microorganisms can adapt even to these harsh conditions.

  5. Weathering of post-impact hydrothermal deposits from the Haughton impact structure: implications for microbial colonization and biosignature preservation.

    Izawa, M R M; Banerjee, Neil R; Osinski, G R; Flemming, R L; Parnell, J; Cockell, C S


    Meteorite impacts are among the very few processes common to all planetary bodies with solid surfaces. Among the effects of impact on water-bearing targets is the formation of post-impact hydrothermal systems and associated mineral deposits. The Haughton impact structure (Devon Island, Nunavut, Canada, 75.2 °N, 89.5 °W) hosts a variety of hydrothermal mineral deposits that preserve assemblages of primary hydrothermal minerals commonly associated with secondary oxidative/hydrous weathering products. Hydrothermal mineral deposits at Haughton include intra-breccia calcite-marcasite vugs, small intra-breccia calcite or quartz vugs, intra-breccia gypsum megacryst vugs, hydrothermal pipe structures and associated surface "gossans," banded Fe-oxyhydroxide deposits, and calcite and quartz veins and coatings in shattered target rocks. Of particular importance are sulfide-rich deposits and their associated assemblage of weathering products. Hydrothermal mineral assemblages were characterized structurally, texturally, and geochemically with X-ray diffraction, micro X-ray diffraction, optical and electron microscopy, and inductively coupled plasma atomic emission spectroscopy. Primary sulfides (marcasite and pyrite) are commonly associated with alteration minerals, including jarosite (K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6), rozenite FeSO(4)·4(H(2)O), copiapite (Fe,Mg)Fe(4)(SO(4))(6)(OH)(2)·20(H(2)O), fibroferrite Fe(SO(4))(OH)·5(H(2)O), melanterite FeSO(4)·7(H(2)O), szomolnokite FeSO(4)·H(2)O, goethite α-FeO(OH), lepidocrocite γ-FeO(OH) and ferrihydrite Fe(2)O(3)·0.5(H(2)O). These alteration assemblages are consistent with geochemical conditions that were locally very different from the predominantly circumneutral, carbonate-buffered environment at Haughton. Mineral assemblages associated with primary hydrothermal activity, and the weathering products of such deposits, provide constraints on possible microbial activity in the post-impact environment. The initial period of

  6. Antibacterial and bioactive calcium titanate layers formed on Ti metal and its alloys.

    Kizuki, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi


    An antibacterial and bioactive titanium (Ti)-based material was developed for use as a bone substitute under load-bearing conditions. As previously reported, Ti metal was successively subjected to NaOH, CaCl2, heat, and water treatments to form a calcium-deficient calcium titanate layer on its surface. When placed in a simulated body fluid (SBF), this bioactive Ti formed an apatite layer on its surface and tightly bonded to bones in the body. To address concerns regarding deep infection during orthopedic surgery, Ag(+) ions were incorporated on the surface of this bioactive Ti metal to impart antibacterial properties. Ti metal was first soaked in a 5 M NaOH solution to form a 1 μm-thick sodium hydrogen titanate layer on the surface and then in a 100 mM CaCl2 solution to form a calcium hydrogen titanate layer via replacement of the Na(+) ions with Ca(2+) ions. The Ti material was subsequently heated at 600 °C for 1 h to transform the calcium hydrogen titanate into calcium titanate. This heat-treated titanium metal was then soaked in 0.01-10 mM AgNO3 solutions at 80 °C for 24 h. As a result, 0.1-0.82 at.% Ag(+) ions and a small amount of H3O(+) ions were incorporated into the surface calcium titanate layers. The resultant products formed apatite on their surface in an SBF, released 0.35-3.24 ppm Ag(+) ion into the fetal bovine serum within 24 h, and exhibited a strong antibacterial effect against Staphylococcus aureus. These results suggest that the present Ti metals should exhibit strong antibacterial properties in the living body in addition to tightly bonding to the surrounding bone through the apatite layer that forms on their surfaces in the body.

  7. UV and IR Spectroscopy of Cold H2O(+)-Benzo-Crown Ether Complexes.

    Inokuchi, Yoshiya; Ebata, Takayuki; Rizzo, Thomas R


    The H2O(+) radical ion, produced in an electrospray ion source via charge transfer from Eu(3+), is encapsulated in benzo-15-crown-5 (B15C5) or benzo-18-crown-6 (B18C6). We measure UV photodissociation (UVPD) spectra of the (H2O·B15C5)(+) and (H2O·B18C6)(+) complexes in a cold, 22-pole ion trap. These complexes show sharp vibronic bands in the 35 700-37 600 cm(-1) region, similar to the case of neutral B15C5 or B18C6. These results indicate that the positive charge in the complexes is localized on H2O, giving the forms H2O(+)·B15C5 and H2O(+)·B18C6, in spite of the fact that the ionization energy of B15C5 and B18C6 is lower than that of H2O. The formation of the H2O(+) complexes and the suppression of the H3O(+) production through the reaction of H2O(+) and H2O can be attributed to the encapsulation of hydrated Eu(3+) clusters by B15C5 and B18C6. On the contrary, the main fragment ions subsequent to the UV excitation of these complexes are B15C5(+) and B18C6(+) radical ions; the charge transfer occurs from H2O(+) to B15C5 and B18C6 after the UV excitation. The position of the band origin for the H2O(+)·B18C6 complex (36323 cm(-1)) is almost the same as that for Rb(+)·B18C6 (36315 cm(-1)); the strength of the intermolecular interaction of H2O(+) with B18C6 is similar to that of Rb(+). The spectral features of the H2O(+)·B15C5 complex also resemble those of the Rb(+)·B15C5 ion. We measure IR-UV spectra of these complexes in the CH and OH stretching region. Four conformers are found for the H2O(+)·B15C5 complex, but there is one dominant form for the H2O(+)·B18C6 ion. This study demonstrates the production of radical ions by charge transfer from multivalent metal ions, their encapsulation by host molecules, and separate detection of their conformers by cold UV spectroscopy in the gas phase.

  8. Detection of water proximity to tryptophan residues in proteins by single photon radioluminescence.

    Bicknese, S; Zimet, D; Park, J; van Hoek, A N; Shohet, S B; Verkman, A S


    We recently developed a single photon radioluminescence (SPR) technique to measure submicroscopic distances in biological samples [Bicknese et al., and Shahrokh et al., Biophys. J., 63 (1992) 1256-1279]. SPR arises from the excitation of a fluorophore by the energy deposited from a slowing beta decay electron. The purpose of this study was to detect 3H2O molecules near tryptophan residues in proteins by tryptophan SPR. To detect small SPR signals, a sample compartment with reflective ellipsoidal optics was constructed, and amplified signals from a cooled photomultiplier were resolved by pulse-height analysis. A Monte Carlo calculation was carried out to quantify the relationship between SPR signal and 3H2O-tryptophan proximity. Measurements of tryptophan SPR were made on aqueous tryptophan; dissolved melittin (containing a single tryptophan); native and denatured aldolase; dissolved aldolase, monellin, and human serum albumin; and the integral membrane proteins CHIP28 (containing a putative aqueous pore) and MIP26 using 3H2O or the aqueous-phase probe 3H-3-O-methylglucose (OMG). After subtraction of a Bremsstrahlung background signal, the SPR signal from aqueous tryptophan (cps.microCi-1 mumol-1 +/- SE) was 8.6 +/- 0.2 with 3H2O and 7.8 +/- 0.3 with 3HOMG (n = 8). With 3H2O as donor, the SPR signal (cps.microCi-1 mumol-1) was 9.0 +/- 0.3 for monomeric melittin in low salt (trytophan exposed) and 4.6 +/- 0.8 (n = 9) for tetrameric melittin in high salt (tryptophans buried away from aqueous solution). The ratio of SPR signal obtained for aldolase under denaturing conditions of 8 M urea (fluorophores exposed) versus non-denaturing buffer (fluorophores buried) was 1.53 +/- 0.07 (n = 6). Ratios of SPR signals normalized to fluorescence intensities for monellin, aldolase, and human serum albumin, relative to that for d-tryptophan, were 1.42, 1.09, and 1.04, indicating that the cross-section for excitation of fluorophores in proteins is greater than that for tryptophan in

  9. A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

    Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.


    Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra showing Pearson's r values >0.94 for the correlations between the four different SOA types after five hours of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxygenated OA (SV-OOA) observed in the ambient aerosol. The atomic O:C ratios were found to be in the range of 0.25-0.55 with no major increase during the first five hours of aging. On average, the diesel SOA showed the lowest O:C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions revealed that the SOA source with the highest O:C ratio had the largest fraction of small ions. The HR data of the four sources could be clustered and separated using principal component analysis (PCA). The model showed a significant separation of the four SOA types and clustering of the duplicate experiments on the first two principal components (PCs), which explained 79% of the total variance. Projection of ambient SV-OOA spectra resolved by positive matrix factorization (PMF) showed that this approach could be useful to identify large contributions of the tested SOA sources to SV-OOA. The first results from this

  10. Myths about the proton. The nature of H+ in condensed media.

    Reed, Christopher A


    Recent research has taught us that most protonated species are decidedly not well represented by a simple proton addition. What is the actual nature of the hydrogen ion (the "proton") when H(+), HA, H2A(+), and so forth are written in formulas, chemical equations, and acid catalyzed reactions? In condensed media, H(+) must be solvated and is nearly always dicoordinate, as illustrated by isolable bisdiethyletherate salts having H(OEt2)2(+) cations and weakly coordinating anions. Even carbocations such as protonated alkenes have significant C-H···anion hydrogen bonding that gives the active protons two-coordinate character. Hydrogen bonding is everywhere, particularly when acids are involved. In contrast to the normal, asymmetric O-H···O hydrogen bonding found in water, ice, and proteins, short, strong, low-barrier (SSLB) H-bonding commonly appears when strong acids are present. Unusually low frequency IR νOHO bands are a good indicator of SSLB H-bonds, and curiously, bands associated with group vibrations near H(+) in low-barrier H-bonding often disappear from the IR spectrum. Writing H3O(+) (the Eigen ion), as often appears in textbooks, might seem more realistic than H(+) for an ionized acid in water. However, this, too, is an unrealistic description of H(aq)(+). The dihydrated H(+) in the H5O2(+) cation (the Zundel ion) gets somewhat closer but still fails to rationalize all the experimental and computational data on H(aq)(+). Researchers do not understand the broad swath of IR absorption from H(aq)(+), known as the "continuous broad absorption" (cba). Theory has not reproduced the cba, but it appears to be the signature of delocalized protons whose motion is faster than the IR time scale. What does this mean for reaction mechanisms involving H(aq)(+)? For the past decade, the carborane acid H(CHB11Cl11) has been the strongest known Brønsted acid. (It is now surpassed by the fluorinated analogue H(CHB11F11).) Carborane acids are strong enough to protonate

  11. Mechanisms and Rates of U(VI) Reduction by Fe(II) in Homogeneous Aqueous Solution and the Role of U(V) Disproportionation.

    Collins, Richard N; Rosso, Kevin M


    Molecular-level pathways in the aqueous redox transformation of uranium by iron remain unclear, despite the importance of this knowledge for predicting uranium transport and distribution in natural and engineered environments. As the relative importance of homogeneous versus heterogeneous pathways is difficult to probe experimentally, here we apply computational molecular simulation to isolate rates of key one electron transfer reactions in the homogeneous pathway. By comparison to experimental observations the role of the heterogeneous pathway also becomes clear. Density functional theory (DFT) and Marcus theory calculations for all primary monomeric species at pH values ≤7 show for UO2(2+) and its hydrolysis species UO2OH(+) and UO2(OH)2(0) that reduction by Fe(2+) is thermodynamically favorable, though kinetically limited for UO2(2+). An inner-sphere encounter complex between UO2OH(+) and Fe(2+) was the most stable for the first hydrolysis species and displayed an electron transfer rate constant ket = 4.3 × 10(3) s(-1). Three stable inner- and outer-sphere encounter complexes between UO2(OH)2(0) and Fe(2+) were found, with electron transfer rate constants ranging from ket = 7.6 × 10(2) to 7.2 × 10(4) s(-1). Homogeneous reduction of these U(VI) hydrolysis species to U(V) is, therefore, predicted to be facile. In contrast, homogeneous reduction of UO2(+) by Fe(2+) was found to be thermodynamically unfavorable, suggesting the possible importance of U(V)-U(V) disproportionation as a route to U(IV). Calculations on homogeneous disproportionation, however, while yielding a stable outer-sphere U(V)-U(V) encounter complex, indicate that this electron transfer reaction is not feasible at circumneutral pH. Protonation of both axial O atoms of acceptor U(V) (i.e., by H3O(+)) was found to be a prerequisite to stabilize U(IV), consistent with the experimental observation that the rate of this reaction is inversely correlated with pH. Thus, despite prevailing notions

  12. Atomic modelling of crystal/complex fluid/crystal contacts—Part I. The genetic iterative multi-species (GIMS) approach and case of kaolinite/brine/kaolinite

    Jouanna, P.; Pèpe, G.; Dweik, J.; Gouze, P.


    Predicting the impact of underground engineering on the environment requires the knowledge of natural media at different scales. In particular, understanding basic phenomena controlling the properties of rocks in the presence of complex fluids necessitates a detailed atomic description of the solid/fluid/solid contacts, the subject of Part I of the present study. First, building the solid interspace between two different crystals in a non-periodic situation is achieved using the ab initio and molecular mechanics code GenMol TM. A description of the fluid confined within the interspace is then derived from the original genetic iterative multi-species (GIMS) algorithm implemented in the same code. This approach consists of equilibrating chemical potentials, cycle after cycle and species after species, between the confined fluid and the free natural fluid. An elementary iteration for a species k consists of different steps incrementing the number Nk of particles k, with other numbers Nk' remaining constant. At each step, an optimum fluid composition is obtained by a genetic process distributing the fluid particles on a grid by stochastic shots, followed in fine by a refining process. The effectiveness of the GIMS approach is demonstrated in the case study of a fluid confined between two (0 0 1) kaolinite faces, with apertures h varying between 4 and 10 Å, connected to a 9-species external solution [H 2O, Cl -, N a+, CO 2(aq), NaCl (aq), Ca 2+, Mg 2+, HCO3-, H 3O +] where concentrations are ranging from 55 to 10 -4 mol/L. The results show a drastic variation in the solute/solvent and cations/ions ratios in the confined fluid when aperture h is lowered to less than 1 nm. These results obtained with a very rapid convergence of the iterative algorithm combined with a very competitive genetic optimizer are validated with high precision on a free solution. This description of contacts between crystals is original and unattainable by standard crystal interface approaches

  13. Atmospheric, Ionospheric, and Energetic Radiation Environments of Saturn's Rings

    Cooper, J. F.; Kollmann, P.; Sittler, E. C., Jr.; Johnson, R. E.; Sturner, S. J.


    Planetary magnetospheric and high-energy cosmic ray interactions with Saturn's rings were first explored in-situ during the Pioneer 11 flyby in 1979. The following Voyager flybys produced a wealth of new information on ring structure and mass, and on spatial structure of the radiation belts beyond the main rings. Next came the Cassini Orbiter flyover of the rings during Saturn Orbital Insertion in 2004 with the first in-situ measurements of the ring atmosphere and plasma ionosphere. Cassini has since fully explored the radiation belt and magnetospheric plasma region beyond the main rings, discovering how Enceladus acts as a source of water group neutrals and water ions for the ion plasma. But do the main rings also substantially contribute by UV photolysis to water group plasma (H+, O+, OH+, H2O+, H3O+, O2+) and neutrals inwards from Enceladus? More massive rings, than earlier inferred from Pioneer 11 and Voyager observations, would further contribute by bulk ring ice radiolysis from interactions of galactic cosmic ray particles. Products of these interactions include neutron-decay proton and electron injection into the radiation belts beyond the main rings. How does radiolysis from moon and ring sweeping of the radiation belt particles compare with direct gas and plasma sources from the main rings and Enceladus? Can the magnetospheric ion and electron populations reasonably be accounted for by the sum of the ring-neutron-decay and outer magnetospheric inputs? Pioneer 11 made the deepest radial penetration into the C-ring, next followed by Cassini SOI. What might Cassini's higher-inclination proximal orbits reveal about the atmospheric, ionospheric, and energetic radiation environments in the D-ring and the proximal gap region? Recent modeling predicts a lower-intensity innermost radiation belt extending from the gap to the inner D-ring. Other remaining questions include the lifetimes of narrow and diffuse dust rings with respect to plasma and energetic particle

  14. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VII. Further Insights into the Chromosphere and Corona

    Robitaille P.-M.


    Full Text Available In the liquid metallic hydrogen model of the Sun, the chromosphere is responsible for the capture of atomic hydrogen in the solar atmosphere and its eventual re-entry onto the photospheric surface (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere. Prog. Phys., 2013, v. 3, L15–L21. As for the corona, it represents a diffuse region containing both gaseous plasma and condensed matter with elevated electron affinity (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere V. On the Nature of the Corona. Prog. Phys., 2013, v. 3, L22–L25. Metallic hydrogen in the corona is thought to enable the continual harvest of electrons from the outer reaches of the Sun, thereby preserving the neutrality of the solar body. The rigid rotation of the corona is offered as the thirty-third line of evidence that the Sun is comprised of condensed matter. Within the context of the gaseous models of the Sun, a 100 km thick transition zone has been hypothesized to exist wherein temperatures increase dramatically from 104–106 K. Such extreme transitional temperatures are not reasonable given the trivial physical scale of the proposed transition zone, a region adopted to account for the ultra-violet emission lines of ions such as C IV, O IV, and Si IV. In this work, it will be argued that the transition zone does not exist. Rather, the intermediate ionization states observed in the solar atmosphere should be viewed as the result of the simultaneous transfer of protons and electrons onto condensed hydrogen structures, CHS. Line emissions from ions such as C IV, O IV, and Si IV are likely to be the result of condensation reactions, manifesting the involvement of species such as CH4, SiH4, H3O+ in the synthesis of CHS in the chromosphere. In addition, given the presence of a true solar surface at the level of the photosphere in the liquid metallic hydrogen model

  15. The link between organic aerosol mass loading and degree of oxygenation: an α-pinene photooxidation study

    Pfaffenberger, L.; Barmet, P.; Slowik, J. G.; Praplan, A. P.; Dommen, J.; Prévôt, A. S. H.; Baltensperger, U.


    A series of smog chamber (SC) experiments was conducted to identify factors responsible for the discrepancy between ambient and SC aerosol degree of oxygenation. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer is used to compare mass spectra from α-pinene photooxidation with ambient aerosol. Composition is compared in terms of the fraction of particulate CO2+, a surrogate for carboxylic acids, vs. the fraction of C2H3O+, a surrogate for aldehydes, alcohols and ketones, as well as in the Van Krevelen space, where the evolution of the atomic hydrogen-to-carbon ratio (H : C) vs. the atomic oxygen-to-carbon ratio (O : C) is investigated. Low (near-ambient) organic mass concentrations were found to be necessary to obtain oxygenation levels similar to those of low-volatility oxygenated organic aerosol (LV-OOA) commonly identified in ambient measurements. The effects of organic mass loading and OH (hydroxyl radical) exposure were decoupled by inter-experiment comparisons at the same integrated OH concentration. An OH exposure between 3 and 25 × 107 cm-3 h is needed to increase O : C by 0.05 during aerosol aging. For the first time, LV-OOA-like aerosol from the abundant biogenic precursor α-pinene was produced in a smog chamber by oxidation at typical atmospheric OH concentrations. Significant correlation between measured secondary organic aerosol (SOA) and reference LV-OOA mass spectra is shown by Pearson's R2 values larger than 0.90 for experiments with low organic mass concentrations between 1.2 and 18 μg m-3 at an OH exposure of 4 × 107 cm-3 h, corresponding to about two days of oxidation time in the atmosphere, based on a global mean OH concentration of ~ 1 × 106 cm-3. α-Pinene SOA is more oxygenated at low organic mass loadings. Because the degree of oxygenation influences the chemical, volatility and hygroscopic properties of ambient aerosol, smog chamber studies must be performed at near-ambient concentrations to accurately simulate

  16. Nicotiana tabacum as model for ozone - plant surface reactions

    Jud, Werner; Fischer, Lukas; Wohlfahrt, Georg; Tissier, Alain; Canaval, Eva; Hansel, Armin


    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. The ensuing injuries have been related to the uptake of ozone through the stomatal pores and oxidative effects damaging the internal leaf tissue. A striking question of current research is the environment and plant specific partitioning of ozone loss between gas phase, stomatal or plant surface sink terms. Here we show results from ozone fumigation experiments using various Nicotiana Tabacum varieties, whose surfaces are covered with different amounts of unsaturated diterpenoids exuded by their glandular trichomes. Exposure to elevated ozone levels (50 to 150 ppbv) for 5 to 15 hours in an exceptionally clean cuvette system did neither result in a reduction of photosynthesis nor caused any visible leaf damage. Both these ozone induced stress effects have been observed previously in ozone fumigation experiments with the ozone sensitive tobacco line Bel-W3. In our case ozone fumigation was accompanied by a continuous release of oxygenated volatile organic compounds, which could be clearly associated to their condensed phase precursors for the first time. Gas phase reactions of ozone were avoided by choosing a high enough gas exchange rate of the plant cuvette system. In the case of the Ambalema variety, that is known to exude only the diterpenoid cis-abienol, ozone fumigation experiments yield the volatiles formaldehyde and methyl vinyl ketone (MVK). The latter could be unequivocally separated from isomeric methacrolein (MACR) by the aid of a Selective Reagent Ion Time-of-Flight Mass Spectrometer (SRI-ToF-MS), which was switched every six minutes from H3O+ to NO+ primary ion mode and vice versa. Consistent with the picture of an ozone protection mechanism caused by reactive diterpenoids at the leaf surface are the results from dark-light experiments. The ozone loss obtained from the

  17. A little adjustment of synthetic strategy led to a new highly repeated heteropolyblue: Structure, characterizations and photocatalytic properties

    Chen, Wu-Hua; Zhang, Zhu-Sen; Zhao, Jin-Hua; Qiu, Ze-Hai; Yuan, Qiu-Lan; Huang, Tian-Fu; Lin, Xue-Yu; Hu, Zhi-Biao


    Hydrothermal synthesis is known as the most efficient method to prepare novel structural polyoxometalate (POM)-based materials, but controlled synthesis of a structure-directing POM is always challenging task. The experimental repeatability is usually one of the key topics. To explore a reliable hydrothermal synthesis approach for new POMs will be a meaningful work. Our previous work, which we have hydrothermally synthesized the first Cr-complexes-capped Keggin-type POM, [Hdma]3[H2phen]{[Cr(phen)]2[MoV8MoVI4O36(PO4)]}·nH2O (n ≈ 2) (Chen et al., polyhedron, 2015, 85, 117), afford us some commendable synthetic experiences, arouse us some introspections as well for its tricky preparation conditions and low experimental repeatability. Based on the aforementioned work, a new high-repetition-rate and more steady heteropolyblue, [H3O]0.5(Hdma)2.5(dma)0.25{[Cr(phen)]2[MoV6MoVI6O8(PO4)]}·2H2O (1) (dma = dimethylamine (C2H7N), phen = 1,10-phenanthroline (C12H8N2)), has been successfully obtained by virtue of reasonably adjusting synthetic strategy. The adjustment of synthetic strategy includes controlling ratio of reactants and aging time, reasonably using redoxes and stepwise self-assembly plans. Compound 1 is the second POM with Keggin-type polyanion capped by Cr-complexes. Experiments demonstrate that compound 1 has good catalytic activity in the both degradation reactions of rhodamine B (RHB) and methyl orange (MO) under ultraviolet (UV)-light and oxidant H2O2 conditions. Detailed structural characterizations include single-crystal X-ray diffraction (XRD) analyses, energy-dispersive X-ray spectrometry (EDS) analyses, elemental analyses, cerate oxidimetry, powder XRD, fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible-near-infrared (UV-Vis-NIR) solid diffuse reflection spectrum and X-ray photoelectron spectroscopy (XPS) analyses. The electrochemical property (cyclic voltammetry (CV)) of compound 1 has also been studied.

  18. New extended magnetic systems based on oxalate and iron(III) ions.

    Armentano, Donatella; Mastropietro, Teresa F; De Munno, Giovanni; Rossi, Patrizia; Lloret, Francesc; Julve, Miguel


    A series of oxalate-bridged iron(III) complexes have been synthesized by the reaction of FeCl 3 with oxalic acid (H 2ox) and XCl, where X is a substituted univalent ammonium or an alkaline cation. We have obtained basically two different types of compounds by varying the nature and the shape of the counterion, with the dimensionality of the resulting product being strongly influenced by the counterion. Three-dimensional (3D) networks of oxo- and oxalato-bridged iron(III) ions of the general formula {X 2[Fe 2O(ox) 2Cl 2]. pH 2O} n have been obtained for X = Li (+) ( 1), Na (+) ( 2), and K (+) ( 3) with p = 4 and X = MeNH 3 (+) ( 4), Me 2NH 2 (+) ( 5), and EtNH 3 (+) ( 6) with p = 2. Similar 3D hydroxo- and oxalato-bridged iron(III) networks of the formula {X[Fe 2(OH)(ox) 2Cl 2].2H 2O} n resulted for X = EtNH 3 (+) ( 7a) and PrNH 3 (+) ( 8). Compound 7a undergoes a solid-to-solid transformation, leading to a new species of the formula {(H 3O)(EtNH 3)[Fe 2O(ox) 2Cl 2].H 2O} n ( 7b). Chainlike compounds of the formula {X 2[Fe 2(ox) 2Cl 4]. pH 2O} n [X = Me 2NH 2 (+)( 9, p = 1), Me 3NH (+) ( 10, p = 2), and Me 4N (+) ( 11, p = 0)] have been obtained for the bulkier alkylammonium cations. Magnetic susceptibility measurements in the temperature range 1.9-295 K show the occurrence of weak ferromagnetic ordering due to spin canting in the 3D networks 1- 8, with the value of the critical temperature ( T c) varying with the cation in the range 26 K ( 2) to 70 K ( 8) without significant structural modifications. The last three one-dimensional compounds exhibit the typical behavior of antiferromagnetically coupled chains of interacting spin sextets [ J = -8.3 ( 9), -6.9 ( 10), and -8.4 ( 11) cm (-1) with H = - J summation operator i S i S i+1 ].

  19. Cassini Plasma Spectrometer Ion Observations Close to Enceladus: E3, E5 and E7

    Tokar, R. L.; Johnson, R. E.; Thomsen, M. F.; Wilson, R. J.; Crary, F. J.; Young, D. T.; Goldstein, R.; Reisenfeld, D. B.; Sittler, E. C.; Coates, A. J.; Paty, C. S.; Jia, Y.; Omidi, N.; Russell, C.


    The Cassini Plasma Spectrometer (CAPS) detected freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier water dimer ions (HxO2)+ very close to Enceladus where the plasma begins to emerge from the south polar plume (1). The data were obtained during two close (52 and 25 km) flybys of Enceladus in 2008 (E3 and E5) and are consistent with measurements from the Cassini Ion Neutral Mass Spectrometer (INMS). The ions are observed in CAPS detectors looking in the Cassini ram direction close to the ram kinetic energy, indicative of a nearly stagnant plasma flow in the plume. North of Enceladus the plasma slowing commences about 4 to 6 Enceladus radii away, while south of Enceladus signatures of the plasma interaction with the plume are detected 22 Enceladus radii away. Here we review and contrast these observations including the E7 flyby (anticipated Nov. 2, 2009). E7 is planned for a closest approach ~103 km south of Enceladus and CAPS should detect ions at rest with respect to Enceladus and over a broad range of gyrophase angles. Plasma fluid parameters both upstream and downstream of these encounters are extracted from the CAPS data. In addition, we compare the CAPS ion measurements with both fluid and 3D hybrid simulations. The MHD simulations (BATSRUS) are tuned to agree with Cassini Magnetometer (MAG) observations during the encounters then compared with CAPS observations. For example, for the E3 encounter the CAPS/BATSRUS comparison is striking, with features reproduced such as: the overall spatial scale of the interaction, the slowing of the ion flow within the dust plume to less than 5 km/s with respect to Enceladus, the temperature, flow and density signature of the geometric wake, and the flow perturbation along the magnetic field due to wake expansion. For E5, BATSRUS tuned against MAG suggests a 15 km/s bulk plasma flow toward Saturn during the encounter. We search for signatures of this flow in the CAPS ion data. 1.) Tokar,R.L. et al. Geophys. Res

  20. Solar wind ion impacts into ice surfaces: A molecular-dynamics study using the REAX force field

    Anders, Christian; Urbassek, Herbert M.


    Molecular dynamics simulation is used to study the effects of solar-wind ion irradiation on an ice target, focusing on the effects of nuclear energy deposition. A reactive force field (REAX) interatomic interaction potential is employed that allows us to model the breaking and formation of molecular bonds and hence to follow the chemistry occurring in the target. As ions we study H and He ions as typical constituents of the solar wind, and Ne as an example of a heavier ion; they impact at the speed of maximum flux in the solar wind, 400 km/s. The ice consists of a mixture of H2O, CO2, CH3OH and NH3. We find that molecular dissociations occur within 0.2 ps after ion impact and new products are formed up to a time of 1 ps; only water has a slower dynamics, due to highly mobile H atoms allowing for late recombinations. The number of dissociations, and hence also of product molecules increases from H over He to Ne ion projectiles and can be quantified by the amount of energy deposited in the target by these ions. The most abundant products formed include CO, OH and NH2. Reaction products are most complex for Ne impact, and include H3O, formaldehyde (H2CO), HO2, and NO. Formaldehyde is important as it is formed relatively frequently and is known as a precursor in the formation of sugars. In addition, molecules containing all CHON elements are formed, among which are CH2NO, CONH, methanolamine (CH5NO), and ethyne (C2H2). Repeated impacts generate novel, and more complex product species; we found CN, CH4, CH3NO, methylamine (CH3NH2), and acetamide (CH3CONH2), among others; the complex species are formed less frequently than the simple fragments. Sputtering occurs for all projectiles, even H. The ejecta are either original molecules - in particular CO2 - or simple fragments; only few product molecules are emitted.

  1. Use of Manganese(II)-Schiff Base Complexes for Carrying Polar Organometallics and Inorganic Ion Pairs.

    Gallo, Emma; Solari, Euro; Floriani, Carlo; Chiesi-Villa, Angiola; Rizzoli, Corrado


    This report concerns the carrier properties of [Mn(acacen)]-derived compounds toward polar organometallics, inorganic ion pairs, and salts. Such properties are the consequence of Mn(II) behaving as a Lewis acid and the O&arcraise;O bite of the bidentate Schiff base ligand toward alkali cations. The starting compounds, which occur in a dimeric form, [Mn(acac-L-en)](2) [L' = CH(2)CH(2) (1); L" = C(6)H(10) (2); L"' = R,R-C(6)H(10) (3)] have been synthesized either via a metathesis reaction from MnCl(2) or using [Mn(3)Mes(6)]. The reaction of 1-3 with lithium organometallics allowed the isolation of [Mn(acac-L-en)(R)Li(DME)] [R = Me, L = L' (4); R = Ph, L = L' (5); R = Mes, L = L' (6); R = Me, L = L" (7); R = Me, L = L"' (8)] as metalated forms, where the alkyl or aryl group is sigma-bonded to Mn(II), while the lithium cation is anchored to the Schiff base ligand. The metalated forms 4-8 react with PhCHO to give the corresponding lithium alkoxide, which remains bound in its ion-pair form to the [Mn(acacen)] skeleton in [Mn(2)(acac-L'-en)(2)Li(2)(OCH(Ph)Me)(2)](n)() (9). The use of 8, which has a chiral bridge across two nitrogen atoms, did not lead to a significant asymmetric induction in the reaction with PhCHO, because of the long separation between the lithium cation and the stereogenic center. The metalated form 4 was able to transfer the methyl group to the nitrile function to give the corresponding lithium-imide which then remains bonded to [Mn(acacen)] as the ion pair in a dimeric structure, as revealed for [Mn(2)(acac-L'-en)(2)Li(2)(DME){N=C(Ph)Me}(2)](n)() (10). Their reaction with 1 appears to depend on the steric bulkiness of the alkyl group in NaOR, resulting in either monomeric adducts, i.e. in [Mn(acac-L'-en)(2,6-Bu(t)(2)C(6)H(3)O)Na(DME)(2)] (11.2DME), or polymeric structures, like in [Mn(acac-L'-en)Na(DME)(&mgr;-OEt)](n)() (13). All the dimeric units reported in this paper show a slight antiferromagnetic coupling between the two Mn(II) assisted by

  2. Elucidating the Role of the Proximal Cysteine Hydrogen Bonding Network in Ferric Cytochrome P450cam and corresponding mutants using Magnetic Circular Dichroism Spectroscopy†

    Galinato, Mary Grace I.; Spolitak, Tatyana; Ballou, David P.; Lehnert, Nicolai


    , 28570, and 28620 cm-1, respectively. The small shift of this feature upon altering the hydrogen bonds to the proximal cysteine indicates that the role of the Cys pocket is not primarily for electronic fine tuning of the sulfur donor strength, but is more for stabilizing the proximal thiolate against external reactants (NO, O2, H3O+), and for properly positioning cysteine to coordinate to the iron center. This aspect is discussed in detail. PMID:21158478

  3. Robust Multifunctional Yttrium-Based Metal-Organic Frameworks with Breathing Effect.

    Firmino, Ana D G; Mendes, Ricardo F; Antunes, Margarida M; Barbosa, Paula C; Vilela, Sérgio M F; Valente, Anabela A; Figueiredo, Filipe M L; Tomé, João P C; Paz, Filipe A Almeida


    Phosphonate- and yttrium-based metal-organic frameworks (MOFs), formulated as [Y(H5btp)]·5.5H2O (1), [Y(H5btp)]·2.5H2O (2), (H3O)[Y2(H5btp)(H4btp)]·H2O (3), and [Y(H5btp)]·H2O·0.5(MeOH) (4), were prepared using a "green" microwave-assisted synthesis methodology which promoted the self-assembly of the tetraphosphonic organic linker [1,1'-biphenyl]-3,3',5,5'-tetrayltetrakis(phosphonic acid) (H8btp) with Y(3+) cations. This new family of functional materials, isolated in bulk quantities, exhibits a remarkable breathing effect. Structural flexibility was thoroughly studied by means of X-ray crystallography, thermogravimetry, variable-temperature X-ray diffraction, and dehydration and rehydration processes, ultimately evidencing a remarkable reversible single-crystal to single-crystal (SC-SC) transformation solely through the loss and gain of crystallization solvent molecules. Topologically, frameworks remained unaltered throughout this interconversion mechanism, with all compounds being binodal 6,6-connected network with a Schäfli symbol of {4(13).6(2)}{4(8).6(6).8}. Results show that this is one of the most stable and thermally robust families of tetraphosphonate-based MOFs synthesized reported to date. Porous materials 2 and 3 were further studied to ascertain their performance as heterogeneous catalysts and proton conductors, respectively, with outstanding results being registered for both materials. Compound 2 showed a 94% conversion of benzaldehyde into (dimethoxymethyl)benzene after just 1 h of reaction, among the best results registered to date for MOF materials. On the other hand, the protonic conductivity of compound 3 at 98% of relative humidity (2.58 × 10(-2) S cm(-1)) was among the highest registered among MOFs, with the great advantage of the material to be prepared using a simpler and sustainable synthesis methodology, as well as exhibiting a good stability at ambient conditions (temperature and humidity) over time when compared to others.

  4. Thermodynamics for complex formation between palladium(ii) and oxalate.

    Pilný, Radomír; Lubal, Přemysl; Elding, Lars I


    Complex formation between [Pd(H2O)4](2+) and oxalate (ox = C2O4(2-)) has been studied spectrophoto-metrically in aqueous solution at variable temperature, ionic strength and pH. Thermodynamic parameters at 298.2 K and 1.00 mol dm(-3) HClO4 ionic medium for the complex formation [Pd(H2O)4](2+) + H2ox ⇄ [Pd(H2O)2(ox)] + 2H3O(+) with equilibrium constant K1,H (in mol dm(-3)) are log10K1,H = 3.38 ± 0.08, ΔH = -33 ± 3 kJ mol(-1), and ΔS = -48 ± 11 J K(-1) mol(-1), as determined from spectrophotometric equilibrium titrations at 15.0, 20.0, 25.0 and 31.0 °C. Thermodynamic overall stability constants β (in (mol dm(-3))(-n), n = 1,2) for [Pd(H2O)2(ox)] and [Pd(ox)2](2-) at zero ionic strength and 298.2 K, defined as the equilibrium constants for the reaction Pd(2+) + nox(2-) ⇄ [Pd(ox)n](2-2n) (water molecules omitted) are log10β = 9.04 ± 0.06 and log10β = 13.1 ± 0.3, respectively, calculated by use of Specific Ion Interaction Theory from spectrophotometric titrations with initial hydrogen ion concentrations of 1.00, 0.100 and 0.0100 mol dm(-3) and ionic strengths of 1.00, 2.00 or 3.00 mol dm(-3). The values derived together with literature data give estimated overall stability constants for Pd(ii) compounds such as [Pd(en)(ox)] and cis-[Pd(NH3)2Cl2], some of them analogs to Pt(ii) complexes used in cancer treatment. The palladium oxalato complexes are significantly more stable than palladium(ii) complexes with monodentate O-bonding ligands. A comparison between several different palladium complexes shows that different parameters contribute to the stability variations observed. These are discussed together with the so-called chelate effect.

  5. Molecular dynamics investigation of ferrous-ferric electron transfer in a hydrolyzing aqueous solution: Calculation of the pH dependence of the diabatic transfer barrier and the potential of mean force

    Rustad, James R.; Rosso, Kevin M.; Felmy, Andrew R.


    We present a molecular model for ferrous-ferric electron transfer in an aqueous solution that accounts for electronic polarizability and exhibits spontaneous cation hydrolysis. An extended Lagrangian technique is introduced for carrying out calculations of electron-transfer barriers in polarizable systems. The model predicts that the diabatic barrier to electron transfer increases with increasing pH, due to stabilization of the Fe3+ by fluctuations in the number of hydroxide ions in its first coordination sphere, in much the same way as the barrier would increase with increasing dielectric constant in the Marcus theory. We have also calculated the effect of pH on the potential of mean force between two hydrolyzing ions in aqueous solution. As expected, increasing pH reduces the potential of mean force between the ferrous and ferric ions in the model system. The magnitudes of the predicted increase in diabatic transfer barrier and the predicted decrease in the potential of mean force nearly cancel each other at the canonical transfer distance of 0.55 nm. Even though hydrolysis is allowed in our calculations, the distribution of reorganization energies has only one maximum and is Gaussian to an excellent approximation, giving a harmonic free energy surface in the reorganization energy F(ΔE) with a single minimum. There is thus a surprising amount of overlap in electron-transfer reorganization energies for Fe2+-Fe(H2O)63+, Fe2+-Fe(OH)(H2O)52+, and Fe2+-Fe(OH)2(H2O)+ couples, indicating that fluctuations in hydrolysis state can be viewed on a continuum with other solvent contributions to the reorganization energy. There appears to be little justification for thinking of the transfer rate as arising from the contributions of different hydrolysis states. Electronic structure calculations indicate that Fe(H2O)62+-Fe(OH)n(H2O)6-n(3-n)+ complexes interacting through H3O2- bridges do not have large electronic couplings.

  6. Quantification of Hydroxyl Radical reactivity in the urban environment using the Comparative Reactivity Method (CRM)

    Panchal, Rikesh; Monks, Paul


    Hydroxyl (OH) radicals play an important role in 'cleansing' the atmosphere of many pollutants such as, NOx, CH4 and various VOCs, through oxidation. To measure the reactivity of OH, both the sinks and sources of OH need to be quantified, and currently the overall sinks of OH seem not to be fully constrained. In order to measure the total rate loss of OH in an ambient air sample, all OH reactive species must be considered and their concentrations and reaction rate coefficients with OH known. Using the method pioneered by Sinha and Williams at the Max Plank Institute Mainz, the Comparative Reactivity Method (CRM) which directly quantifies total OH reactivity in ambient air without the need to consider the concentrations of individual species within the sample that can react with OH, has been developed and applied in a urban setting. The CRM measures the concentration of a reactive species that is present only in low concentrations in ambient air, in this case pyrrole, flowing through a reaction vessel and detected using Proton Transfer Reaction - Mass Spectrometry (PTR-MS). The poster will show a newly developed and tested PTR-TOF-MS system for CRM. The correction regime will be detailed to account for the influence of the varying humidity between ambient air and clean air on the pyrrole signal. Further, examination of the sensitivity dependence of the PTR-MS as a function of relative humidity and H3O+(H2O) (m/z=37) cluster ion allows the correction for the humidity variation, between the clean humid air entering the reaction vessel and ambient air will be shown. NO, present within ambient air, is also a potential interference and can cause recycling of OH, resulting in an overestimation of OH reactivity. Tests have been conducted on the effects of varying NO concentrations on OH reactivity and a correction factor determined for application to data when sampling ambient air. Finally, field tests in the urban environment at the University of Leicester will be shown

  7. Br?nsted Acid Ionic Liquid Activated Electrodes Catalyze Water Electrolysis for Production of Hydrogen%BrÖnsted酸性离子液体活化电极催化制氢性能研究

    陈佳志; 孟玲祎; 王雅静; 孟晋磊; 江峰; 楚哲; 刘洪涛


    分别采用玻碳( GC)、铂( Pt)和金( Au)电极研究了在BrÖnsted酸性离子液体[ HMIm] HSO4中电解水制氢的催化活性,活性大小为Pt > Au >> GC。水中离子液体的含量对析氢电流影响很大,当[ HMIm] HSO4含量为30%(V/V)时,Pt电极催化电解水产氢的阈值电位高达-0.3 V (Ag丝为准参比电极, Ag QRE),在-0.5 V (Ag QRE)处电流密度高达110.52 mA/cm2,为相同条件下Au电极的15倍,GC电极的650倍。计算结果表明,Pt电极在该电解液中的反应活化能为5.68 kJ/mol。电极的高催化活性与[ HMIm] HSO4电离产生的质子有关,使水以H3 O+的形式捕集电子,效率更高。%The water electrolysis for production of hydrogen in the Br?nsted acid ionic liquid [ HMIm] HSO4 aqueous solutions was investigated using glassy carbon ( GC ) , platinum ( Pt ) , and gold ( Au ) electrodes, respectively. It was found that the catalytic activity of the electrodes in the acid ionic liquid electrolytes ranked in sequence as Pt > Au >> GC. The optimal concentration of [ HMIm] HSO4 in aqueous solutions was 30%( V/V ) , and the catalytic current density on Pt electrode for hydrogen evolution reaction ( HER ) at-0. 5 V (Ag QRE) reached 110. 52 mA/cm2. This was 15 and 650-fold larger than the current on the Au and GC electrode, respectively. The Arrhenius activation energy of the Pt electrode in the electrolyte solution was 5. 68 kJ/mol. The high catalytic activity of the electrode was attributed to the [ HMIm] HSO4 that would release protons enabling H2 O molecules ionization, and facilitating the capture of electrons from the electrode.

  8. Global Time Variability in the Thermal Plasma Composition of the Saturnian Magnetosphere

    Ip, W.


    The Saturnian magnetosphere is characterized by strong coupling between the charged particles and the neutral gas cloud emitted from Enceladus and the rings. Besides the mass-loading effect due to ionization of the water-group gas, the charge transfer process leading to the generation of energetic neutral atoms is a key process of particle loss and atmospheric precipitation. Detailed measurements by the plasma instruments like CAPS and MIMI have provided many insights to the magnetospheric composition and dynamics driven by such plasma-gas interaction. For example, a statistical study of the CAPS measurements by Thomsen et al. (2010) has shown the relative abundances and radial profiles of different ion species in the corotating thermal plasma disc. Another interesting result has to do with the seasonal variability of the suprathermal O2+ molecular ions detected by the CHEMS/MIMI experiment (Christon et al., 2013) which might have to do with the extended oxygen atmosphere of the ring system (Tseng et al., 2010). In this work, we will use a time-dependent radial diffusion transport model coupled with ion chemistry calculation (Ip, 2000) to simulate the global distributions of various ions (H+, H2+, O+, OH+, H2O+, H3O+, and O2+ )between the outer edge of the A ring to the orbit of Titan. Our parametric study will examine how the thermal ion composition of the Saturnian magnetosphere would be affected by solar cycle effect, seasonal variation of the ring atmosphere, and the suprathermal electron flux. Christon, S.P., Hamilton, D.C., DiFabio, R.D., Mitchell, D.G., Krimigis, S.M., and Jontof-Hutter, D.S., J. Geophys. Res., 118, 3446-3462, 2013. Ip, W.-H., Planet. Space Sci., 48, 775-783, 2000. Thomsen, M.F., Reisenfeld, D.B., Delapp, D.M., Tokar, R.C., Young, D.T., Crary, F.J., Sittler, E.C., McGraw, M.A., and Williams, J.D., J. Geophys. Res., 115, A10220, 2010. Tseng, W.-L., Ip, W.-H., Johnson, R.E., Cassidy, T.A., and Elrod, M.K., Icarus, 206, 382-389, 2010.

  9. Construction of Six Coordination Polymers Based on a 5,5′-(1,2-Ethynyl)bis-1,3-benzenedicarboxylic Ligand: Synthesis, Structure, Gas Sorption, and Magnetic Properties

    Zheng, Bing


    Six novel coordination polymers based on a multifunctional ligand, 5,5\\'-(1,2-ethynyl)bis-1,3-benzenedicarboxylic (H4EBDC), namely, |(C3H7NO)2(H2O)7(C 2H5OH)3| [Zn2(C18H 6O8)(C10H8N2) 2] (1), |(C3H7NO)3(H2O)30- (CH3CN)2|[Zn 6(C18H6O8)3(C 6H12N2O2)2] (2), |(C 3H7NO)2- (H2O)2(H 3O)2|[Cd3(C18H6O 8)2] (3), |(C3H7NO)|[Mn- (C 18H8O8)(C3H7NO) 2] (4), |(C3H7NO)2(H2O)(C 2H7N)3| [Mn6(C18H 7O8)4(H2O)8] (5), and [Mn2(C18H6O8)(C3H 7NO)2] (6), have been constructed under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction. In these compounds, the ligand, H4EBDC, exhibits different coordination modes and conformations, constructing various architectures by bridging a variety of metal ions or polynuclear clusters. Compound 1 forms a three-dimensional (3D) FSC network constructed from two-dimensional (2D) layer motifs joined by EBDC4- and 4,4\\'-bipyridine bridges. Compound 2 possesses an NbO topology by linking Zn2(CO2)4 units with the ligand, coordinated amine molecules fill the pores, while compound 3 exhibits a 3D FLU network with Cd2+ as the cation and features an infinite framework built from tricadmium clusters. Compound 4 is based on PtS net, constructed of 4-connected rectangular H4EBDC units with tetrahedral monometallic Mn(CO2)4 nodes. Compound 5 is composed of 2D layers with (3,6)-connected KGD topology, and compound 6 consists of a 3D PtS-X network, built by bridging a metal chain with the ligand. The structures of these compounds have been discussed together with their corresponding properties, such as gas storage, separation, and magnetic properties. © 2013 American Chemical Society.

  10. Bridging function mediated intermetallic coupling in diruthenium-bis(bipyridine) complexes

    Soma Chakraborty; Biplab Mondal; Biprajit Sarkar; Goutam Kumar Lahiri


    The interactions of potentially dinucleating bridging functionalities (I-VI) with the ruthenium-bis(bypyridine) precursor [RuII(bpy)2(EtOH)2]2+ have been explored. The bridging functions I, II and VI directly result in the expected dinuclear complexes of the type [(bpy)2RuII{L}RuII(bpy)2]+ (1, 2, 7 and 8) ( = 0, = 4 and = -2, = 2). The bridging ligand III undergoes N-N or N-C bond cleavage reaction on coordination to the RuII(bpy)2 core which eventually yields a mononuclear complex of the type [(bpy)2RuII(L)]+, 3, where L = -OC6H3(R)C(R′)=N-H. However, the electrogenerated mononuclear ruthenium(III) congener, 3+ in acetonitrile dimerises to [(bpy)2RuIII {-OC6H3(R)C(R′)=N-N=(R′)C(R)C6H3O-}RuIII(bpy)2]4+ (4). In the presence of a slight amount of water content in the acetonitrile solvent the dimeric species (4) reduces back to the starting ruthenium(II) monomer (3). The preformed bridging ligand IV undergoes multiple transformations on coordination to the Ru(bpy)2 core, such as hydrolysis of the imine groups of IV followed by intermolecular head-to-tail oxidative coupling of the resultant amino phenol moieties, which in turn results in a new class of dimeric complex of the type [(bpy)2RuII {-OC6H4-N=C6H3(=NH)O-}RuII(bpy)2]2+ (5). In 5, the bridging ligand comprises of two , chelating binding sites each formally in the semiquinone level and there is a -benzoquinonediimine bridge between the metal centres. In complex 6, the preformed bridging ligand, 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2-dihydro-1,2,4,5- tetrazine, H2L (V) undergoes oxidative dehydrogenation to aromatic tetrazine based bridging unit, 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine, L. The detailed spectroelectrochemical aspects of the complexes have been studied in order to understand the role of the bridging units towards the intermetallic electronic coupling in the dinuclear complexes.

  11. Análise Complexa e Geometria Diferencial de certas Superfícies do Espaço hiperbólico

    Ricardo Sa Earp


    Full Text Available Desde os tempos de Gauss, Riemann e de outros que a GeometriaDiferencial entrelaça-se com a Análise Complexa. Um dos mais belos efeitos disto é a bem conhecida representação de Weierstrass para superfícies mínimas de R^3, consistindo de dados meromorfos (f,g que descrevem inteiramente uma tal superfície. O estudo da análise complexa aplicado neste contexto, ao longo das últimas décadas,tem produzido vertiginosos resultados e tem desenvolvido esta teoria para além das expectativas. Já é bem conhecido que as superfícies mínimas simplesmente conexas de R^3 pode-se associar suas primas no espaço hiperbólico tridimensional H^3 que possuem curvatura média igual a 1. Tal relação segue do teorema fundamental da Geometria, calcado nas equações de Gauss e de Codazzi-Mainardi. O fato é quetambém existem dados meromorfos sobre as superfícies de curvatura média 1 em H^3, o que sob um ponto de vista filosófico é de se esperar. Este é o escopo destas notas: Explicar um pouco as origens desta teoria e suas ligações com a teoria clássica das superfícies mínimas de R^3 e apresentar os dados meromorfos e exemplos, segundo um trabalho recente do autor com Toubiana. Como o espço hiperbólicopossui vários modelos naturais, diferentemente do espaço Euclideano, existem vários pontos de vistas alternativos nesta teoria revelando a riqueza inigualável da Geometria Hiperólica. Isto tem sido estabelecido por R. Bryant, Umehara,Yamada que são os pioneiros na moderna abordagem deste assunto. Notáveis trabalhos nesta área também têm sido compilados por Rossman, Small, Rosenberg, Collin, Hausswirth e Toubiana. De modo que fervilham resultados que exibem a pujança do link Análse Complexa, Geometria Hiperbólica & Geometria Diferencial.

  12. Syntheses, Structural Characterizations and Properties of Some Novel Polyoxomolybdates Linked by Coordinated Transition Metal or Lanthanide Cations%一些配位过渡金属或稀土连结的多钼酸化合物的合成、结构及性能研究

    吴传德; 卢灿忠


    利用简单的手性有机配体L-酒石酸成功地合成出了一系列类似DNA螺旋构型的左、右旋的一维链状聚合物:{A[Mo()2O4LnⅢ(H2O)6(C4H2O6)2]·4H2O}n(Ln=Sm,Eu,Gd,Ho,Yb,Y;C4H2O6=L-或D-酒石酸;A=NH4或H3O).通过水热法,巧妙地把传统的钼氧单核{ MoO4}、双核{Mo2O7}以及{Mo8O26}等结构单元,通过有机配体配位的过渡金属单元交错地连接成零、一、二、三维的一系列结构新颖的化合物,这类化合物大多数具有可以容纳客体小分子的隧道或空穴,如[Cu(4,4'-bpy)]2MoO4·2H2O,[Cu(4,4'-bpy)]2Mo2O7,[Cu(4,4'-bpy)(Hnic)(H2O)]2Mo8O26等.首次利用水热法合成出了含稀土的杂多酸类化合物,[Gd(H2O)3]3[GdMo12O42]·3H2O.该化合物是由Silverton型的[GdMo12O42]9-阴离子和配位的Gd3+阳离子组成的.在[GdMo12O42]9-离子中首次把顺磁性的钆(Ⅲ)离子引入到该构型的中心,并且通过九配位的钆(Ⅲ)离子把它们连接成具有介孔结构的三维网状化合物.该化合物的获得为今后合成类似化合物提供了一个很好的范例.在水热法合成出的化合物[Cu2(C8H6N2)2(C7H6N2)]2[Mo8O26]中,首次捕捉到喹喔啉的氧化产物苯并咪唑,证明了在水热条件下含氮的芳香杂环类的有机配体可以被二价铜氧化,其氧化产物进而作为配体直接与铜原子配位,最终形成新颖的上述化合物.%A series of novel double helicates, {A[Mo2ⅥO4LnⅢ (H2O)6(C4H2O6)2]·4H2O}n(Ln =Sm, Eu, Gd, Ho, Yb, Y; C4H2O6 = L-tartaric acid; A = NH4 or H3O), have been synthesized from the reactions of chiral ligands L-tartaric acid with molybdates as well as lanthanide cations. The architectures of these compounds are one dimensional enantiopure novel right- or left-handed double helical one-dimensional chains, which are somehow like DNA in general configurations. By the hydrothermal reaction method, some molybdenum oxide units such as { MoO4 }, { Mo2 O7 } , { Mo8 O26 } are linked up by transition metal/organic ligand

  13. Solution structures, stabilities, kinetics, and dynamics of DO3A and DO3A-sulphonamide complexes.

    Takács, Anett; Napolitano, Roberta; Purgel, Mihály; Bényei, Attila Csaba; Zékány, László; Brücher, Ernő; Tóth, Imre; Baranyai, Zsolt; Aime, Silvio


    The Gd(3+)-DO3A-arylsulphonamide (DO3A-SA) complex is a promising pH-sensitive MRI agent. The stability constants of the DO3A-SA and DO3A complexes formed with Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) ions are similar, whereas the logKLnL values of Ln(DO3A-SA) complexes are 2 orders of magnitude higher than those of the Ln(DO3A) complexes. The protonation constant (log KMHL) of the sulphonamide nitrogen in the Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) complexes is very similar to that of the free ligand, whereas the logKLnHL values of the Ln(DO3A-SA) complexes are lower by about 4 logK units, indicating a strong interaction between the Ln(3+) ions and the sulphonamide N atom. The Ln(HDO3A-SA) complexes are formed via triprotonated *Ln(H3DO3A-SA) intermediates which rearrange to the final complex in an OH(-)-assisted deprotonation process. The transmetalation reaction of Gd(HDO3A-SA) with Cu(2+) is very slow (t1/2 = 5.6 × 10(3) h at pH = 7.4), and it mainly occurs through proton-assisted dissociation of the complex. The (1)H and (13)C NMR spectra of the La-, Eu-, Y-, and Lu(DO3A-SA) complexes have been assigned using 2D correlation spectroscopy (COSY, EXSY, HSQC). Two sets of signals are observed for Eu-, Y-, and Lu(DO3A-SA), showing two coordination isomers in solution, that is, square antiprismatic (SAP) and twisted square antiprismatic (TSAP) geometries with ratios of 86-14, 93-7, and 94-6%, respectively. Line shape analysis of the (13)C NMR spectra of La-, Y- , and Lu(DO3A-SA) gives higher rates and lower activation entropy values compared to Ln(DOTA) for the arm rotation, which indicates that the Ln(DO3A-SA) complexes are less rigid due to the larger flexibility of the ethylene group in the sulphonamide pendant arm. The fast isomerization and the lower activation parameters of Ln(DO3A-SA) have been confirmed by theoretical calculations in vacuo and by using the polarizable continuum model. The solid state X-ray structure of Cu(H2DO3A-SA) shows distorted

  14. The ionization rates of galactic nuclei and disks from Herschel/HIFI observations of water and its associated ions

    van der Tak, F. F. S.; Weiß, A.; Liu, L.; Güsten, R.


    of the Galactic Center and ~100× below estimates for AGN from excited-state H3O+ lines. We conclude that the ground-state lines of water and its associated ions probe primarily non-nuclear gas in the disks of these centrally active galaxies. Our data thus provide evidence for a decrease in ionization rate by a factor of ~10 from the nuclei to the disks of galaxies, as found before for the Milky Way. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  15. Investigation of Heterogeneous Atmospheric Chlorine Chemistry: Modeling and Environmental Chamber Studies Authors: Cameron B. Faxon, Lea Hildebrandt Ruiz, and David Allen University of Texas at Austin, McKetta Department of Chemical Engineering

    Faxon, C. B.; Hildebrandt Ruiz, L.; Allen, D.


    Previous work has shown that gas phase atomic chlorine radicals (Cl*) can influence tropospheric photochemistry, including concentrations of volatile organic compound (VOC) and ozone. These radicals are produced through both gas phase and heterogeneous pathways. This work presents computational and experimental investigation into the heterogeneous reactions of chloride aerosols. An overview of a sensitivity analysis of the physical parameters involved in the heterogeneous production of nitryl chloride (ClNO2) (R1-R5) will comprise the computational work presented. NO2(g) + NO3(g) ↔ N2O5(g) (R1) N2O5(aq) ↔ N2O5(aq) (R2) N2O5(aq) ↔ NO2+(aq) + NO3-(aq) (R3) NO2+(aq) + H2O(aq) → H3O+(aq) + HNO3(aq) (R4a) NO2+(aq) + Cl- → ClNO2 + H2O(aq) (R4b) NO3-(aq) + H+ ↔ HNO3+(aq) (R5) Relative parameters include the reactive uptake coefficient, ClNO2 yield, particle surface area, and gas phase concentrations of VOCs and NOx. The sensitivity analysis results were generated through photochemical box modeling and focus on the production of ClNO2 and impacts to ozone production. Results were compared to a base case scenario in which all heterogeneous reactions were absent. Parameter values reaching the upper limits reported in the literature were tested, and results indicate that ClNO2 chemistry can potentially change peak O3 concentrations by -10.5% to 27%. NOx availability was also found to play an important role. Experimental results of the heterogeneous reaction between OH* and particulate chloride (R6-R7) will also be discussed. The mechanism is shown below, and OH***Cl- represents an intermediate species forming at the particle surface. OH(g) + Cl-(aq) → OH***Cl-(aq) (R6) 2OH***Cl-(aq) → Cl2,g + 2OH-(aq) (R7) Environmental chamber experiments involving the exposure of NaCl aerosol particles to typical atmospheric conditions (HOx, NOx, O3 and UV radiation) were performed. A 10 cubic meter teflon reaction chamber equipped with UV lights was used to contain the

  16. Recuperação de gotejadores obstruídos devido à utilização de águas ferruginosas Recovery of drippers clogged by use of water high in iron content

    Gustavo H. S. Vieira


    Full Text Available Desenvolveu-se este trabalho com o objetivo de se avaliar a eficiência da utilização de ácido fosfórico, de hipoclorito de sódio e de um produto comercial, além do impacto mecânico na desobstrução de gotejadores entupidos, devido à utilização de águas com elevado teor de ferro. O trabalho foi realizado na Fazenda Vista Alegre, localizada em Jaboticatubas, MG. Um sistema de irrigação por gotejamento foi adaptado para realização dos testes com oito tratamentos, sendo sete com aplicação de produtos químicos e um com impacto mecânico. Para os tratamentos químicos, utilizaram-se: o ácido fosfórico com pH 2 e pH 3; o hipoclorito de sódio com as dosagens de 100, 50 e 25 mg L-1 de cloro; e Reciclean com as dosagens de 50 e 25 mg L-1. Diante dos resultados obtidos, conclui-se: o tratamento com ácido fosfórico em pH 2 forneceu o melhor resultado quanto ao aumento da uniformidade de aplicação de água pelo sistema, apresentando o maior aumento nos valores de coeficiente de uniformidade de distribuição (CUD e coeficiente de uniformidade de Christiansen (CUC; entretanto, com custo elevado. O tratamento com 25 mg L-1 de cloro apresentou a melhor relação benefício/custo, sendo o mais econômico e o segundo melhor quanto à melhoria da uniformidade de irrigação do sistema. O impacto mecânico é uma alternativa para recuperação de sistemas de irrigação por gotejamento em geral, com destaque para sistemas de cultivos orgânicos.A study was carried out (Reciclean to evaluate the efficiency of using the phosphoric acid, sodium hypochlorite, a commercial product and mechanical impact for cleaning the drippers in which the clogging was due to the presence of high iron content in water. The experiment was set up in the Vista Alegre Farm, located in Jaboticatubas County - Minas Gerais State. A drip irrigation system was adopted for the accomplishment of the tests. Eight treatments were tested, of which, seven with application

  17. 水蒸气处理对Ni2P/SiO2催化剂催化氯苯加氢脱氯反应的促进作用%Promotion Effect of Steam Treatment on Activity of Ni2P/SiO2 for Hydrodechlorination of Chlorobenzene

    郭提; 陈吉祥; 李克伦


    Ni2P/SiO2 was pretreated with a 0.8%H3O-99.2%H2 flow at 303, 514, and 543 K. The Ni2P/SiO2 catalysts before and after treatment were characterized by N2 adsorption-desorption, X-ray diffraction, inductively coupled plasma atomic emission spectrometry, H2 temperature-programmed desorption, and in situ diffuse reflection infrared Fourier transform spectroscopy, and their activities in the hy-drodechlorination of chlorobenzene (CB) were tested in a fix-bed reactor. There was no difference in BET specific surface area, pore structure, the Ni2P crystallite size, the Ni content, and the Ni/P ratio for the Ni2P/SiO2 catalysts before and after treatment. The treatment at 303 K did not decrease the density of exposed Ni sites on Ni2P/SiO2, while the treatment at 514 and 543 K led to the decrease of exposed Ni sites and the increase of the P-OH groups on Ni2P/SiO2. Under the conditions of 513 K, the CB space velocity of 3.75 ml/(gh), and the H2/CB molar ratio of 9.0, the initial CB conversions on the treated NbP/SiO2 catalysts exceeded 93.8%, which was much higher than that (5.6%) on the untreated one. The promotion effect of steam treatment on the activity of Ni2P/SiO2 may be related to a synergism between the Ni sites and the P-OH groups.%在303,514和543K下用0.8%H2O-99.2%H2对Ni2P/SiO2催化剂进行了水蒸气处理,利用N2吸附-脱附、X射线衍射、电感耦合等离子体发射光谱、H2程序升温脱附及原位漫反射红外光谱等技术对水蒸气处理前后Ni2P/SiO2催化剂的结构进行了表征,并在常压固定床反应器上评价了其催化氯苯加氢脱氯活性.结果表明,经水蒸气处理后,Ni2P/SiO2催化剂的物相及元素组成、Ni2P晶粒大小、比表面积及孔结构没有明显改变.与未处理和303K处理的Ni2P/SiO2催化剂不同,513和543K处理的催化剂表面暴露的Ni中心数量减少,表面P-OH基团数量增多.在513K,氯苯空速3.75ml/(g·h)及H2和氯苯的摩尔比为9.0的反

  18. Selective-Reagent-Ionization Mass Spectrometry: New Prospects for Atmospheric Research

    Sulzer, Philipp; Jordan, Alfons; Hartungen, Eugen; Hanel, Gernot; Jürschik, Simone; Herbig, Jens; Märk, Lukas; Märk, Tilmann D.


    Proton-Transfer-Reaction Mass Spectrometry (PTR-MS), which was introduced to the scientific community in the 1990's, has quickly evolved into a well-established technology for atmospheric research and environmental chemistry [1]. Advantages of PTR-MS are i) high sensitivities of several hundred cps/ppbv, ii) detection limits at or below the pptv level, iii) direct injection sampling (i.e. no sample preparation), iv) response times in the 100 ms regime and v) online quantification. However, one drawback is a somehow limited selectivity, as in case of quadrupole mass filter based instruments only information about nominal m/z are available. In Time-Of-Flight (TOF) mass analyzer based instruments selectivity is drastically increased by a high mass resolution of up to 8000 m/Δm, but e.g. isomers still cannot be separated. In 2009 we introduced an advanced version of PTR-MS, which permits switching the reagent ions from H3O+ to NO+ and O2+, respectively [2]. This novel type of instrumentation was called Selective-Reagent-Ionization Mass Spectrometry (SRI-MS) and has been successfully used to separate isomers, e.g. the biogenic compounds isoprene and 2-methyl-3-buten-2-ol as shown by Karl et al. [3]. Switching the reagent ions dramatically increases selectivity and thus applicability of SRI-MS in atmospheric research. Here we report on the latest results utilizing an even more advanced embodiment of SRI-MS enabling the use of the additional reagent ions Kr+ and Xe+ [4]. With this technology important atmospheric compounds, such as CO2, CO, CH4, O2, etc. can be quantified and selectivity is increased even further. We present comparison data between diesel and gasoline car exhaust gases and quantitative data on indoor air for these compounds, which are not detectable with classical PTR-MS. Additionally, we show very recent examples of isomers which cannot be separated with PTR-MS but can clearly be distinguished with SRI-MS. Finally, we give an overview of ongoing SRI

  19. Mechanistic pathways of mercury removal from the organomercurial lyase active site

    Pedro J. Silva


    only after protonation by solvent-provided H3O+. Thiolate addition to the active site (prior to any attack by thiols leads to pathways where the removal of the first cysteine becomes the rate-determining step, irrespective of whether Cys159 or Cys96 leaves first. Comparisons with the recently computed mechanism of the related enzyme MerA further underline the important role of Asp99 in the energetics of the MerB reaction. Kinetic simulation of the mechanism derived from our computations strongly suggests that in vivo the thiolate-only pathway is operative, and the Asp-assisted pathway (as well as the conversion of intermediates of the thiolate pathway into intermediates of the Cys-assisted pathway is prevented by steric factors absent from our model and related to the precise geometry of the organomercurial binding-pocket.

  20. Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces.

    Gerber, R Benny; Varner, Mychel E; Hammerich, Audrey D; Riikonen, Sampsa; Murdachaew, Garold; Shemesh, Dorit; Finlayson-Pitts, Barbara J


    isolated defects where it involves formation of H3O(+)-acid anion contact ion pairs. This behavior is found in simulations of a model of the ice quasi-liquid layer corresponding to large defect concentrations in crystalline ice. The results are in accord with experiments. (iv) Ionization of acids on wet quartz. A monolayer of water on hydroxylated silica is ordered even at room temperature, but the surface lattice constant differs significantly from that of crystalline ice. The ionization processes of HCl and H2SO4 are of high yield and occur in a few picoseconds. The results are in accord with experimental spectroscopy. (v) Photochemical reactions on water and ice. These simulations require excited state quantum chemical methods. The electronic absorption spectrum of methyl hydroperoxide adsorbed on a large ice cluster is strongly blue-shifted relative to the isolated molecule. The measured and calculated adsorption band low-frequency tails are in agreement. A simple model of photodynamics assumes prompt electronic relaxation of the excited peroxide due to the ice surface. SEMD simulations support this, with the important finding that the photochemistry takes place mainly on the ground state. In conclusion, dynamics simulations using quantum chemical potentials are a useful tool in atmospheric chemistry of water media, capable of comparison with experiment.

  1. Rational design of ion force fields based on thermodynamic solvation properties.

    Horinek, Dominik; Mamatkulov, Shavkat I; Netz, Roland R


    Most aqueous biological and technological systems contain solvated ions. Atomistic explicit-water simulations of ionic solutions rely crucially on accurate ionic force fields, which contain most commonly two adjustable parameters: the Lennard-Jones diameter and the interaction strength. Assuming these parameters to be properly optimized, the plethora of parameters one finds in the literature for one and the same ion is surprising. In principle, the two parameters should be uniquely determined by matching two ionic properties obtained for a particular water model and within a given simulation protocol with the corresponding experimental observables. Traditionally, ion parameters were chosen in a somewhat unsystematic way to reproduce the solvation free energy and to give the correct ion size when compared with scattering results. Which experimental observable one chooses to reproduce should in principle depend on the context within which the ionic force field is going to be used. In the present work we suggest to use the solvation free energy in conjunction with the solvation entropy to construct thermodynamically sound force fields for the alkali and halide ions for the simulation of ion-specific effects in aqueous environment. To that end we determine the solvation free energy and entropy of both cations and anions in the entire relevant parameter space. As an independent check on the quality of the resulting force fields we also determine the effective ionic radius from the first peak of the radial ion-water distribution function. Several difficulties during parameter optimization are discussed in detail. (i) Single-ion solvation depends decisively on water-air surface properties, which experimentally becomes relevant when introducing extrathermodynamic assumptions on the hydronium (H(3)O(+)) solvation energy. Fitting ion pairs circumvents this problem but leaves the parameters of one reference ion (here we choose chloride) undetermined. (ii) For the halides the

  2. Effect Of Gas Mixture Composition On Tar Removal Process In A Pulsed Corona Discharge Reactor

    Filimonova E.; Naidis, G.


    The simulation of naphthalene (C10H8) removal from several gas mixtures (pure nitrogen, mixtures containing N2 with CO2, CO, H2, H2O, and biogas - the product of biomass gasification), has been investigated. The modeling is based on the experimental data obtained in the reactor with a pulsed positive corona discharge. The problem of simulation of the cleaning process includes description of two stages. The first, fast stage is generation of primary active species during streamer propagation. The second, slow stage is the chain of chemical transformations triggered by these species. The input parameters for the modeling of the second stage are G-values for generation of primary active species, obtained under consideration of streamer dynamics. Simulation of the second stage of the removal process takes into account the processes of chemical kinetics and diffusion outside and inside of streamer traces during multi-pulsed treatment. Besides neutral active species, streamer discharges produce electrons and ions. Primary positive ions (N2+, CO+, CO2+, H2+, H2O+) in a chain of fast ion-molecule reactions transform into more stable positive ions. The ions recombine with electrons. Both ion-molecule reactions and electron-ion recombination process are additional (to dissociation of gas molecules by electron impact in the streamer head) sources of neutral active species. The relative contribution of these sources to the G-values for H, OH and O is rather large. In our modeling two approaches have been used. At the first approach the contribution of ion-molecule reactions is estimated approximately assuming that the dominating stable ion is N4+ (in pure N2 and its mixtures with H2) or CO2+ (in mixtures including CO2). Other way is the calculations with kinetic scheme including the molecular ions, aquated ions such as H3O(H2O)m+, NO2(H2O)-, NO2(H2O)+ and other. The comparison of results of two approaches is presented. Only full kinetic scheme allowed describing the

  3. Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O((3)P)+allyl radical intermediate.

    Fitzpatrick, Benjamin L; Alligood, Bridget W; Butler, Laurie J; Lee, Shih-Huang; Lin, Jim Jr-Min


    This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H(2)COCH)CH(2)Cl. The three dominant photoproduct channels analyzed are c-(H(2)COCH)CH(2)+Cl, c-(H(2)COCH)+CH(2)Cl, and C(3)H(4)O+HCl. In the second channel, the c-(H(2)COCH) photofission product is a higher energy intermediate on C(2)H(3)O global potential energy surface and has a small isomerization barrier to vinoxy. The resulting highly vibrationally excited vinoxy radicals likely dissociate to give the observed signal at the mass corresponding to ketene, H(2)CCO. The final primary photodissociation pathway HCl+C(3)H(4)O evidences a recoil kinetic energy distribution similar to that of four-center HCl elimination in chlorinated alkenes, so is assigned to production of c-(H(2)COC)=CH(2); the epoxide product is formed with enough vibrational energy to isomerize to acrolein and dissociate. The paper then analyzes the dynamics of the C(3)H(5)O radical produced from C-Cl bond photofission. When the epoxide radical photoproduct undergoes facile ring opening, it is the radical intermediate formed in the O((3)P)+allyl bimolecular reaction when the O atom adds to an end C atom. We focus on the HCO+C(2)H(4) and H(2)CO+C(2)H(3) product channels from this radical intermediate in this report. Analysis of the velocity distribution of the momentum-matched signals from the HCO+C(2)H(4) products at m/e=29 and 28 shows that the dissociation of the radical intermediate imparts a high relative kinetic energy, peaking near 20 kcal/mol, between the products. Similarly, the energy imparted to relative kinetic energy in the H(2)CO+C(2)H(3) product channel of the O((3)P)+allyl radical intermediate also peaks at high-recoil kinetic energies, near 18 kcal/mol. The strongly forward-backward peaked angular distributions and the high kinetic energy release result from tangential recoil during the dissociation of highly rotationally excited nascent radicals formed photolytically in this

  4. In vitro cytotoxic, antioxidant and antiviral effects of Pterocaulon alopecuroides and Bidens segetum extracts Efeitos citotóxico, antioxidante e antiviral in vitro de extratos de Pterocaulon alopecuroides e Bidens segetum

    Cristiane Silva Silveira


    Full Text Available Pterocaulon alopecuroides (Lamark De Candolle and Bidens segetum Mart. ex Colla are two species belonging to the Asteraceae family. Extracts from those two species were evaluated to their cytotoxic, antioxidant and antiviral activities. All the extracts assayed have shown a very high cytotoxity against RBL-2H3 cell line. The antioxidant assay pointed out a really high activity of the ethyl acetate extracts for B. segetum and P. alopecuroides. This can be partially explained due to the high content of coumarins, at least for P. alopecuroides. None of the total ethanol extracts from B. segetum showed significant activity against the two strains of Herpes simplex virus (Types 1 and 2 resistant to acyclovir. P. alopecuroides ethanol extract was also inactive against the Herpes simplex virus type 1 resistant to acyclovir. However, this extract presented inhibitory activity against the Herpes simplex virus type 2 resistant to acyclovir. From the ethanol crude extract of P. alopecuroides, it was possible to isolate 7-(2',3'-dihidroxy-3'-methylbutyloxy-6-methoxycoumarin, which was tested in the same conditions, showing a viral inhibitory rate almost twice bigger than the P. alopecuroides sample for HSV-2-ACVr. The coumarin was also active against HSV-1-ACVr. Those results provide further evidence of the importance of Pterocaulon alopecuroides and Bidens segetum as medicinal plants.Pterocaulon alopecuroides (Lamark De Candolle e Bidens segetum Mart. ex Colla são duas espécies pertencentes à família Asteraceae. Os extratos dessas duas espécies foram avaliados quanto às suas atividades citotóxica, antioxidante e antiviral. Todos os extratos analisados apresentaram citotoxidade muito alta contra linhagens de células RBL-2H3. O ensaio de atividade antioxidante demonstrou uma alta atividade das frações em acetato de etila de B. segetum e P. alopecuroides. Isso pode ser parcialmente explicado pelo alto conteúdo de cumarinas, ao menos para P

  5. The small bowel flora in individuals with cecoileal reflux Estudo da flora do delgado em doentes com refluxo cecoileal

    Wellington Monteiro Machado


    junção ileocecal exerce função de barreira e proteção contra a invasão do delgado pela flora colônica, realizou-se o presente estudo com a finalidade de investigar se existe contaminação ileal em indivíduos com refluxo cecoileal ao enema opaco. MÉTODOS: Investigaram-se 36 indivíduos, 30 mulheres e 6 homens, idade média de 54 anos, 25 com e 11 com ausência refluxo cecoileal. Todos submetidos a pesquisa de contaminação bacteriana do delgado por intermédio de teste respiratório com lactulose-H2 e a determinação do tempo de trânsito orocecal por meio de biossusceptometria de corrente alternada. A caracterização da contaminação do delgado foi baseada no encurtamento do tempo de trânsito orocecal medido pelo teste da lactulose-H2. RESULTADOS: A comparação dos valores basais do H2, do tempo de trânsito orocecal-H2 e tempo de trânsito orocecal-biossusceptometria de corrente alternada não diferiram estatisticamente entre os grupos com e sem refluxo cecoileal. Quando comparados os tempo de trânsito orocecal-H2 e tempo de trânsito orocecal-biossusceptometria, foi observado aumento de tendência de redução do primeiro em relação ao último nos grupos com refluxo cecoileal e correlação significante entre os dois métodos apenas no grupo-controle, inexistindo nos com refluxo cecoileal. CONCLUSÃO: Encurtamento do tempo de trânsito orocecal-H2 e sua perda de correlação com o tempo de trânsito orocecal-biossusceptometria observado em indivíduos com refluxo cecoileal, sugerem comportamento diferenciado deste grupo em relação ao grupo-controle. Possível explicação para as diferenças registradas entre os grupos, seria a presença de flora anômala nos indivíduos com refluxo cecoileal.

  6. 钾通道在新生大鼠星形胶质细胞缺氧缺血性水肿中的作用机制%Mechanism of potassium channel in hypoxca-ischemic brain edema: experiment with neonatal rat astrocyte

    付雪梅; 向龙; 廖大清; 封志纯; 母得志


    . Aquaporin 4 (AQP4) expression vector was constructed from pSUPER vector and transfected into the astrocytes (AQP4 RNAi) to construct AQP4 knockdown (AQP4-/-) cells, cellular volume was determined using [3H]-3-O-methyld-D-glucose uptake in both AQP4-/- and AQP4+/+ cells under the condition of HI. Real time PCR and Western blotting were used to detect the mRNA and protein expression of AQP4. Results The percentages of the AQP4+/+ and AQP4-/- astrocyte volumes in the condition of HI for 0. 5, 1,2, and 4 h were 104±7, 109±6, 126±12, and 152±9 times, and 97±7, 105±9, 109±7, and 132±6 times as those of their corresponding control groups (all P < 0. 05), thus showing that the cellular volume of both AQP4+/+ and AQP4-/- astrocytes significantly increased during HI and the degrees of edema mediated by AQP4 knockdown at different time points were all significantly milder (all P < 0.05). The current density values at the time points 0. 5, 1,2, and 4 h of the HI group were 107±9, 91±10, 76±6, 37±11, respectively, compared to that of the control group of 116±8, showing a tendency of time-dependent decreasing manner (all P < 0. 05). Conclusion During HI, the dowuregnlation of outward potassium (K+) conductance may prevent the emission of interacellularly accumulated K+ ions, thus resulting in osmotically drived water influx into astrocytes via aquaporin-4 and then cell swelling.

  7. Investigating the pathway for the photochemical formation of VOCs in presence of an organic monolayer at the air/water interface.

    Tinel, Liselotte; Rossignol, Stéphanie; Ciuraru, Raluca; George, Christian


    unsaturated aldehydes were detected and a reaction pathway, initiated by a H-abstraction of the surfactant by the excited HA*, has been proposed. This mechanism infers that the presence of the surface microlayer will enhance protonation and self-reactions, leading to the formation of dimers as suggested in [6]. These products could explain the formation of the unsaturated products observed. To confirm the hypothesis of an initiative step of H-abstraction, the system was simplified using OH radicals, generated by the photolysis of H2O2, in presence of an artificial organic layer of nonanoic acid. The VOCs produced, monitored by PTR/SRI-TOF-MS in NO+ and H3O+ ionization mode, were less abundant compared to the system with HA, but the same classes of products could be observed, including oxidation products such as aldehydes but also unsatured products like dienes. The underlying water was sampled before and after the experiment and analysed by HR-ESI-MS, showing mostly enrichment of oxidative products, such as hydroxy- and keto-acids immediately derived from the photochemical oxidation of the nonanoic acid layer. These products, showing lower volatility and higher polarity, partition preferentially to the bulk water. The results of this simplified system confirm the reaction mechanism proposed and the role an organic layer can play in the photochemical formation of VOCs, which could influence the marine boundary layer chemistry. 1. Peter S. Liss, R.A.D., ed. Sea Surface and Global Change. 1997, Cambridge University Press: Cambridge. 509. 2. Griffith, E.C. and V. Vaida, In situ observation of peptide bond formation at the water-air interface. Proceedings of the National Academy of Sciences, 2012. 109(39): p. 15697-15701. 3. Sinreich, R., et al., Ship-based detection of glyoxal over the remote tropical Pacific Ocean. Atmospheric Chemistry and Physics, 2010. 10(23): p. 11359-11371. 4. Kieber, R.J., X.L. Zhou, and K. Mopper, Formation of carbonyl-compounds from uv

  8. 层间水分子含量对铜铁水滑石超分子作用力的影响%Influence of Interlayer Water Content on Supermolecular Interaction of Copper-Iron Layered Double Hydroxides

    施炜; 胡军; 倪哲明; 李远; 刘娇


    A periodic interaction model was proposed for the copper-iron layered double hydroxides, CusFe-LDHs-yHzO (y=0-2). Based on density functional theory, the geometry of Cu3Fe-LDHs-yH2O was optimized using the CASTEP program. The distribution of NOi and H3O in the interlayer and the supermolecular interaction between host and guest was investigated by analyzing the geometric parameters, hydrogen-bonding, charge populations and stepwise hydration energy. Results indicated that when NO3 and H;O were inserted into the layers of the Cu3Fe-LDHs, there was a strong supramolecular interaction between the host layer and the guest, including hydrogen-bonding and electrostatic interaction. Hydrogen-bonding was superior to the electrostatic interaction in the hydration process. The strength of hydrogen bonding was ordered as Layer-Anion (L-A) > Anion-Water (A-W) > Layer-Water (L-W) > Water -Water (W-W). In Cu3Fe-LDHs-yH;O, the interlayer distance decreased slightly and then increased significantly with an increase in the number of interlayer water molecules. The Cu - O octahedral forms were stretched gradually because of the increased Jahn - Teller effect of Cu2'. The absolute value of the hydration energy decreased gradually with an increase in the number of water molecules. This suggested that the hydration of CujFe-LDHs reached a saturation state. The geometry of Cu3Fe-LDHs-1H2O is close to hexagonal where the metal distortion of the layer is weakest and the stability is strongest; the interlayer distance agrees the experimental value, therefore CujFe-LDHs-IH2O is a stable configuration.%构建铜铁水滑石[Cu3Fe-LDHs-yH2O(y=0-2)]周期性计算模型,采用密度泛函理论(DFT),选取CASTEP程序模块,对体系进行几何全优化.从结构参数、氢键、Mulliken电荷布居、逐级水合能等角度研究了层间NO3-和H2O的分布形态及其与水滑石(LDHs)层板的超分子作用,探究了水分子数目对体系姜-泰勒效应的影响.结果表明:Cu3Fe

  9. Analysis on the heterosis and combining ability of upland cotton with Bt resistance%抗虫陆地棉配合力与杂种优势分析

    商连光; 闫勇; 肖荧南; 王玉美; 华金平


    even reached to 92. 16%. The narrow heritability of F2 for some traits was higher than that of F1. The heterosis was checked in F1 and F2 generations. The heterosis of lint yield in F1 was with an average of 11.31%,34. 17% and 13.33% over competitive control, the mid-parent and high-parent, respectively. The lint yield of a cross of P4/P7 (EZAMIAN 12/5H3O3) showed 27. 4% higher than a local commercial variety Han284. The depression showed in crosses of F2 generation while the heterosis remained in some crosses in F2 generation. The cross P4/P7(EZAMIAN 12/ 5H303) showed the highest specific combining ability (SCA) of yield in the crosses of F1 generation,while the crossesP4/P10 (EZAMIAN 12/5H335), P1/P11 (611/5H336) showed the highest SCA in the crosses of F2 generation. The parent with best general combining ability (GCA) were P8 (5H309) and P5 (5H181) in yield and P1 (611), P2 (05- 5317) ,P4 (EZAMIAN 12). So it is possible to bred commercial hybrid with Bt-resistance of upland cotton by using stocks from different regions.