Sample records for h3o h2do hd2o

  1. Photoionization and fragmentation of H3O+ under XUV irradiation

    DEFF Research Database (Denmark)

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


    The photolysis of the hydronium cation H3O+ has been studied at the extreme ultraviolet wavelengths of 35.56±0.24 nm (34.87±0.24 eV) and 21.85±0.17 nm (56.74±0.44 eV) using a crossed ion-photon beam setup at the free-electron laser FLASH. Coincidence photoelectron and photofragment spectroscopy w...

  2. The C2H3O+ chemi-ion acetyl cation or O-protonated ketene

    DEFF Research Database (Denmark)

    Egsgaard, H.; Carlsen, L.


    The C2H3O+ chemi-ion sampled from a premixed methane/oxygen flame has been demonstrated to be the acetyl cation based on ion-molecule reactions with isoprene and 1,3-dioxolane.......The C2H3O+ chemi-ion sampled from a premixed methane/oxygen flame has been demonstrated to be the acetyl cation based on ion-molecule reactions with isoprene and 1,3-dioxolane....

  3. Synthesis and characterization of a new uranium(V) compound: H3O+UF6-

    International Nuclear Information System (INIS)

    Masson, J.P.; Desmoulin, J.P.; Charpin, P.; Bougon, R.


    The reaction of equimolar amounts of UF 5 and H 2 O in hydrogen fluoride results in the partial dissolution of UF 5 , yielding a blue-green solution from which the new salt oxonium hexafluorouranate(V)(H 3 O + UF 6 - ) could be isolated as a green crystalline solid. Calorimetric measurements showed H 3 O + UF 6 - to decompose at about 68 0 C and its heat of formation to be equal to -628 +- 2 kcal mol. Its ionic nature in the solid state and in HF solutions was demonstrated from vibrational and electronic spectra. The electronic spectrum is closely similar to those of LiUF 6 , NaUF 6 , and CsUF 6 and differs from those of RbUF 6 and KUF 6 . This adduct shows a strong ESR signal, with g = -0.78 +- 0.10, characteristic of UF 6 - salts. Based on its x-ray powder diffraction pattern, H 3 O + UF 6 - is cubic with a = 5.2229 +- 0.0005 A

  4. Investigation into complexing in Re7-H3O+-SO42--H2O system

    International Nuclear Information System (INIS)

    Sinyakova, G.S.


    Using the methods of spectrophotometry and conductometry it is shown, that in the ReO 4 - -H 3 O + -SO 4 2- -H 2 O system interaction between rhenium (7) and sulfuric acid takes place in a wide concentration range. In low-acid solutions at pH 2.0-0.9 rhenium(7) complex with proton is formed at the ratio of 1:1 with lgK 1 =3.30+-0.02. In 1-10 mol. sulfuric acid observed is consecutive complexing at the rhenium(7) - sulfuric acid ratio in the complex of 1:1 and 1:2 respectively with lgK 2 =0.93+-0.13 and lgK 3 =0.34+-0.03. At the background of concentrated perchloric acid rhenium (7) and sodium sulfate form two complex compounds at rhenium (7) - sodium sulfate ratio of 1:1 and 1:2 with lgK 1 =1.86+-0.02 and lgK 2 =2.35+-0.03

  5. A combined HRND and HREM study of degradation collapse in NH4+/H3O+ β"-alumina

    DEFF Research Database (Denmark)

    Thomas, John O.; Eriksson, Anders; Kjems, Jørgen


    High resolution neutron diffraction (HRND) from single crystals, and high resolution electron microscopy (HREM) are combined to study the deammoniation of NH4+/H3O+ β"-alumina on heating above 200°C. HRND shows the emergence of extra reflections which cannot be indexed in terms of the original β...

  6. Cross sections for Scattering and Mobility of OH- and H3 O+ ions in H2 O (United States)

    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.

  7. Energetics of fragmentation of CH5, H3O, and NH4 from neutralized ion-beam experiments

    International Nuclear Information System (INIS)

    Williams, B.W.; Porter, R.F.


    Fragmentation energies for radicals of the type RH 2 (RH=CH 4 , NH 3 , and H 2 O) produced by electron capture interactions of 5 keV RH 2 + ion with Na or K atoms are reported. The experimental technique involves measurement of spatial beam profiles resulting from dissociation of neutral radicals following their formation in a near resonant electron transfer process. Cross sections for RH 2 + --Na capture reactions are typically 1x10 -14 cm 2 . Fragmentation energies from measurements with Na target atoms are -2.65 +- 0.14, -0.22 +- 0.03, and -1.12 +- 0.07 eV for CH 5 , NH 4 , and H 3 O, respectively. From our results with Na and K targets and published values for proton affinities, the vertical electron affinities of CH 5 + and H 3 O + are calculated to be 5.3 +- 0.2 eV and 5.1 +- 0.3 eV, respectively. Beam profiles for ND 4 show this species to be metastable with a lifetime of about 1 μs. From this we estimate a potential barrier to dissociation in NH 4 (ND 4 ) between 0.36 and 0.48 eV, indicating this species should be stable at low temperatures. Comparison of these experimental results with theoretical calculations indicates areas of disagreement

  8. Synthesis, Structure and Thermal Behavior of Oxalato-Bridged Rb+ and H3O+ Extended Frameworks with Different Dimensionalities (United States)

    Kherfi, Hamza; Hamadène, Malika; Guehria-Laïdoudi, Achoura; Dahaoui, Slimane; Lecomte, Claude


    Correlative studies of three oxalato-bridged polymers, obtained under hydrothermal conditions for the two isostructural compounds {Rb(HC2O4)(H2C2O4)(H2O)2}∞1, 1, {H3O(HC2O4)(H2C2O4).2H2O}∞1, 2, and by conventional synthetic method for {Rb(HC2O4)}∞3, 3, allowed the identification of H-bond patterns and structural dimensionality. Ferroïc domain structures are confirmed by electric measurements performed on 3. Although 2 resembles one oxalic acid sesquihydrate, its structure determination doesn’t display any kind of disorder and leads to recognition of a supramolecular network identical to hybrid s-block series, where moreover, unusual H3O+ and NH4+ similarity is brought out. Thermal behaviors show that 1D frameworks with extended H-bonds, whether with or without a metal center, have the same stability. Inversely, despite the dimensionalities, the same metallic intermediate and final compounds are obtained for the two Rb+ ferroïc materials.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    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.

  11. NH4(+) Resides Inside the Water 20-mer Cage As Opposed to H3O(+), Which Resides on the Surface: A First Principles Molecular Dynamics Simulation Study. (United States)

    Willow, Soohaeng Yoo; Singh, N Jiten; Kim, Kwang S


    Experimental vibrational predissociation spectra of the magic NH4(+)(H2O)20 clusters are close to those of the magic H3O(+)(H2O)20 clusters. It has been assumed that the geometric features of NH4(+)(H2O)20 clusters might be close to those of H3O(+)(H2O)20 clusters, in which H3O(+) resides on the surface. Car-Parrinello molecular dynamics simulations in conjunction with density functional theory calculations are performed to generate the infrared spectra of the magic NH4(+)(H2O)20 clusters. In comparison with the experimental vibrational predissociation spectra of NH4(+)(H2O)20, we find that NH4(+) is inside the cage structure of NH4(+)(H2O)20 as opposed to on the surface structure. This shows a clear distinction between the structures of NH4(+)(H2O)20 and H3O(+)(H2O)20 as well as between the hydration phenomena of NH4(+) and H3O(+).

  12. Local work-function changes of Pt(111) studied by STM and IRAS: coadsorption of Cl - with H 3O +, NO, and CO molecules (United States)

    Fukushima, Takashi; Song, Moon-Bong; Ito, Masatoki


    The coadsorption of chloride anion (Cl -) with hydronium cation (H 3O +), nitrogen monoxide (NO), and carbon monoxide (CO) on Pt(111) was studied in an ultra-high-vacuum system using scanning tunneling microscopy (STM), infrared reflection absorption spectroscopy (IRAS), and low-energy electron diffraction (LEED). HCl molecules adsorbed on Pt(111) at 100 K form a (3×3) structure ( θCl -=0.44). Water adsorption on the 3×3 structure produces c(4×2)-(Cl -+H 3O +) coadsorption structures. The hydronium cation adsorbs through oxygen lone pair, and hydrogen bonding (OH…Cl) extends on the surface with these structures. Stretching absorption bands of NO (or CO) adsorbed on the 3×3-Cl - and c(4×2)-(Cl -+H 3O +) adlayers on Pt(111) show remarkably higher and lower frequency shifts, respectively. The frequency shifts can be explained by the local charge density states of platinum atoms derived from electron withdrawal or supply from the coadsorbates (Cl - or H 3O +) to platinum atoms.

  13. Reversible formation of intermediates during H3O+-catalyzed hydrolysis of amides. Observation of substantial 18O exchange accompanying the hydrolysis of acetanilide and N-cyclohexylacetamide

    International Nuclear Information System (INIS)

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


    Careful mass spectrometric analysis of the 18 O content of ∼ 50% enriched acetanilide (2) and N-cyclohexylacetamide (3) recovered from acidic media during the course of hydrolysis reveals that both species suffer 18 O loss. The percent of 18 O exchange per t/sub 1/2/ of hydrolysis increases as [H 3 O + ] decreases. For 2 at 72 0 C the amount of exchange increases from 0.5 +/- 0.5% (per t/sub 1/2/) in 1 M HCl to 9.4 +/- 0.5% in glycine buffer, [H 3 O + ] = 0.003 M. For 3 at 100 0 C the exchange is 1.05 +/- 0.3% (per t/sub 1/2/) at 1 M HCl and 9.0 +/- 0.4% in 0.01 M HCl. When these data are used to compute k/sub ex/ (the exchange rate constant), it shows a first-order dependence on [H 3 O + ] followed by a plateau at high [H 3 O + ] for both 2 and 3

  14. Unraveling the chemical complexity of biomass burning VOC emissions via H3O+ ToF-CIMS (PTR-ToF): emissions characterization (United States)

    Koss, A.; Sekimoto, K.; Gilman, J.; Selimovic, V.; Coggon, M.; Zarzana, K. J.; Yuan, B.; Lerner, B. M.; Brown, S. S.; Jimenez, J. L.; Krechmer, J. E.; Warneke, C.; Yokelson, R. J.; De Gouw, J. A.


    Gas-phase biomass burning emissions can include hundreds, if not thousands, of unique volatile and intermediate-volatility organic compounds. It is crucial to know the composition of these emissions to understand secondary organic aerosol formation, ozone formation, and human health effects resulting from fires. However, the composition can vary greatly with fuel type and fire combustion process. During the FIREX 2016 laboratory intensive at the US Forest Service Fire Sciences Laboratory in Missoula, Montana, high-resolution H3O+-CIMS (PTR-ToF) was deployed to characterize VOC emissions. More than 500 ion masses were consistently enhanced in each of 58 fires, which included a wide variety of fuel types representative of the western United States. Using a combination of extensive literature review, H3O+ and NO+ CIMS with GC preseparation, comparison to other instruments, and mass spectral context, we were able to identify the VOC contributors to 90% of the instrument signal. This provides unprecedented chemical detail in high time resolution. We present chemical characteristics of emissions, including OH reactivity and volatility, and highlight areas where better identification is needed.

  15. Synthesis and properties of ternary (K, NH4, H3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

    International Nuclear Information System (INIS)

    Sandy Jones, F.; Bigham, Jerry M.; Gramp, Jonathan P.; Tuovinen, Olli H.


    The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K + (0, 1, 4, 6, 12, 31 mM) and NH 4 + (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO 4 solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe 3 (SO 4 ) 2 (OH) 6 ) and/or schwertmannite (idealized formula Fe 8 O 8 (OH) 6 (SO 4 )·nH 2 O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K + (≤ 4 mM) and NH 4 + (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K + and NH 4 + are similar, K + greatly facilitated the formation of a jarosite phase compared to NH 4 + . Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH 4 , H 3 O)-solid solutions that were also deficient in structural Fe, especially at low NH 4 contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K + and NH 4 + in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH 4 -jarosite were detected in the un-aged precipitates. - Highlights: • Fe(III) precipitates formed in A. ferrooxidans culture solutions were characterized. • The monovalent cation

  16. Response to Comment on "Synthesis and characterization of the pentazolate anion cyclo-N5- in (N5)6(H3O)3(NH4)4Cl". (United States)

    Jiang, Chao; Zhang, Lei; Sun, Chengguo; Zhang, Chong; Yang, Chen; Chen, Jun; Hu, Bingcheng


    Huang and Xu argue that the cyclo -N 5 - ion in (N 5 ) 6 (H 3 O) 3 (NH 4 ) 4 Cl we described in our report is theoretically unfavorable and is instead protonated. Their conclusion is invalid, as they use an improper method to assess the proton transfer in a solid crystal structure. We present an in-depth experimental and theoretical analysis of (N 5 ) 6 (H 3 O) 3 (NH 4 ) 4 Cl that supports the results in the original paper. Copyright © 2018, American Association for the Advancement of Science.

  17. Crystal structure and thermochemical properties of a novel coordination compound sodium pyruvate C3H3O3Na(s)

    International Nuclear Information System (INIS)

    Gao, Zhen-Fei; Di, You-Ying; Liu, Su-Zhou; Lu, Dong-Fei; Dou, Jian-Min


    Graphical abstract: A novel coordination compound sodium pyruvate C 3 H 3 O 3 Na(s) is synthesised. Elemental analysis and X-ray crystallography are used to characterise the composition and crystal structure of the compound. The lattice potential energy and ionic volume of the anion are obtained from crystallographic data. The standard molar enthalpy of formation of the compound is calculated by an isoperibol solution-reaction calorimeter. Molar enthalpies of dissolution of the compound at various molalities are measured at T = 298.15 K. According to Pitzer’s theory, molar enthalpy of dissolution of the title compound at infinite dilution is calculated. The values of relative apparent molar enthalpies and relative partial molar enthalpies of the solvent and the compound at different concentrations m/(mol · kg −1 ) are derived. - Highlights: • The sodium pyruvate was synthesised and crystal structure was determined. • The enthalpy change of the synthesis reaction was obtained. • Standard molar enthalpy of formation was obtained. • Molar enthalpy of dissolution at infinite dilution was calculated. - Abstract: A novel coordination compound sodium pyruvate C 3 H 3 O 3 Na(s) is synthesised by a liquid phase reaction. The compound has an obvious bioactivity and can be used as the biological carbon source and the chemical identification of primary and secondary alcohols. It can be also used to determinate transaminase. Elemental analysis and X-ray crystallography are used to characterise the composition and crystal structure of the compound. Single crystal X-ray analysis reveals that the compound is formed by one CH 3 COCOO − anion and one Na + cation. An obvious feature of the crystal structure is the formation of the five-membered chelate ring by the coordination of O1 of carboxylate and O3 of keto form with Na + cation, and it is good for the stability of the compound in structure. The lattice potential energy and ionic volume of the anion are obtained

  18. Ion chemistry at elevated ion–molecule interaction energies in a selected ion flow-drift tube: reactions of H3O+, NO+ and O2+ with saturated aliphatic ketones

    Czech Academy of Sciences Publication Activity Database

    Spesyvyi, Anatolii; Smith, D.; Španěl, Patrik


    Roč. 19, č. 47 (2017), s. 31714-31723 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GJ17-13157Y EU Projects: European Commission(XE) 674911 - IMPACT Institutional support: RVO:61388955 Keywords : reactions of H3O+, NO+ and O2+ * SIFT-MS Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

  19. Primary emissions and chemical oxidation of volatile organic compounds emitted from laboratory biomass burning sources during the 2016 FIREX FireLab campaign: measurements from a H3O+ chemical ionization mass spectrometer (United States)

    Coggon, M. M.; Warneke, C.; Koss, A.; Sekimoto, K.; Yuan, B.; Lim, C. Y.; Hagan, D. H.; Kroll, J. H.; Cappa, C. D.; Gilman, J.; Lerner, B. M.; Jimenez, J. L.; Yokelson, R. J.; Roberts, J. M.; De Gouw, J. A.


    Non-methane organic gases (NMOG) emitted by biomass burning constitute a large source of reactive carbon in the atmosphere. Once emitted, these compounds may undergo series of reactions with the OH radical and nitrogen oxides to form secondary organic aerosol (SOA), ozone, or other health-impacting products. The complex emission profile and strong variability of biomass burning NMOG play an important, yet understudied, role in the variability of air quality outcomes such as SOA and ozone. In this study, we summarize measurements of biomass burning volatile organic compounds (VOCs) conducted using a H3O+ chemical ionization mass spectrometer (H3O+-CIMS) during the 2016 FIREX laboratory campaign in Missoula, MT. Specifically, we will present data demonstrating the chemical evolution of biomass burning VOCs artificially aged in a field-deployable photooxidation chamber and an oxidation flow reactor. More than 50 OH-oxidation experiments were conducted with biomass types representing a range of North American fuels. Across many fuel types, VOCs with high SOA and ozone formation potential, such as aromatics and furans, were observed to quickly react with the OH radical while oxidized species were generated. We compare the calculated OH reactivity of the primary emissions to the calculated OH reactivity used in many photochemical models and highlight areas requiring additional research in order to improve model/measurement comparisons.

  20. Magnetic susceptibility and specific heat of the one-dimensional conductor (H3O) sub (1,6) Pt (C2O4)2.nH2O at low temperatures

    International Nuclear Information System (INIS)

    Raede, H.S.


    It has been shown recently that some transition metal complexes exhibit one-dimensional metallic properties. It is reported, in this context, susceptibility and specific heat measurements of polycrystalline (H 3 O) 1 , 6 Pt(C 2 O 4 ) 2 .nH 2 O in the low temperature range. It is found that the susceptibility can be described by a non-uniform Curie law with a characteristic break in the slope. The specific heat reveals no linear temperature contribution, which could be explained by a transition into a Peierls distorted state. Until 13 0 K, the heat capacity follows a T 3 -law. Deviations at higher temperatures are possibly attributed to the anisotropy of the system [pt

  1. Topology-energy relationships and lowest energy configurations for pentagonal dodecahedral (H2O)20X clusters, X=empty, H2O, NH3, H3O+: The importance of O-topology (United States)

    Anick, David J.


    For (H2O)20X water clusters consisting of X enclosed by the 512 dodecahedral cage, X=empty, H2O, NH3, and H3O+, databases are made consisting of 55-82 isomers optimized via B3LYP/6-311++G∗∗. Correlations are explored between ground state electronic energy (Ee) or electronic energy plus zero point energy (Ee+ZPE) and the clusters' topology, defined as the set of directed H-bonds. Linear regression is done to identify topological features that correlate with cluster energy. For each X, variables are found that account for 99% of the variance in Ee and predict it with a rms error under 0.2 kcal/mol. The method of analysis emphasizes the importance of an intermediate level of structure, the "O-topology," consisting of O-types and a list of O pairs that are bonded but omitting H-bond directions, as a device to organize the databases and reduce the number of structures one needs to consider. Relevant variables include three parameters, which count the number of H-bonds having particular donor and acceptor types; |M|2, where M is the cluster's vector dipole moment; and the projection of M onto the symmetry axis of X. Scatter diagrams for Ee or Ee+ZPE versus |M| show that clusters fall naturally into "families" defined by the values of certain discrete parameters, the "major parameters," for each X. Combining "family" analysis and O-topologies, a small group of clusters is identified for each X that are candidates to be the global minimum, and the minimum is determined. For X=H3O+, one cluster with central hydronium lies just 2.08 kcal/mol above the lowest isomer with surface hydronium. Implications of the methodology for dodecahedral (H2O)20(NH4+) and (H2O)20(NH4+)(OH-) are discussed, and new lower energy isomers are found. For MP2/TZVP, the lowest-energy (H2O)20(NH4+) isomer features a trifurcated H-bond. The results suggest a much more efficient and comprehensive way of seeking low-energy water cluster geometries that may have wide applicability.

  2. Application of Co and Mn for a Co-Mn-Br or Co-Mn-C2H3O2 Petroleum Liquid Catalyst from the Cathode Material of Spent Lithium Ion Batteries by a Hydrometallurgical Route

    Directory of Open Access Journals (Sweden)

    Sung-Ho Joo


    Full Text Available We investigated the preparation of CMB (cobalt-manganese-bromide and CMA (cobalt-manganese-acetate liquid catalysts as petroleum liquid catalysts by simultaneously recovering Co and Mn from spent Li-ion battery cathode material. To prepare the liquid catalysts, the total preparation process for the liquid catalysts consisted of physical pre-treatments, such as grinding and sieving, and chemical processes, such as leaching, solvent extraction, and stripping. In the physical pre-treatment process, over 99% of Al was removed from material with a size of less than 0.42 mm. In the chemical process, the leaching solution as obtained under the following conditions: 2 mol/L sulfuric acid, 10 vol % H2O2, 0.1 of solid/liquid ratio, and 60 °C. In the solvent extraction process, the optimum concentration of bis (2,4,4-trimethylpentyl phosphinic acid (Cyanex 272, the equilibrium pH, the degree of saponification, the organic phase/aqueous phase ratio isotherm, and the stripping study for the extraction of Co and Mn were investigated. As a result, Co and Mn were recovered by 0.85 M Cyanex 272 with 50% saponification in counter current two extraction stages. Finally, a CMB and CMA liquid catalyst containing 33.1 g/L Co, 29.8 g/L Mn, and 168 g/L Br and 12.67 g/L Co, 12.0 g/L Mn, and 511 g/L C2H3O2, respectively, was produced by 2 M hydrogen bromide and 50 vol % acetic acid; it was also found that a shortage in the concentration can be compensated with cobalt and manganese salts.

  3. Vibrational spectroscopy of NO + (H2O)n: Evidence for the intracluster reaction NO + (H2O)n --> H3O + (H2O)n - 2 (HONO) at n => 4 (United States)

    Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio


    Infrared spectra of mass-selected clusters NO+(H2O)n for n=1 to 5 were recorded from 2700 to 3800 cm-1 by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second-order Møller-Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H2O ligands bound to a nitrosonium ion NO+ core. They possessed perturbed H2O stretch bands and dissociated by loss of H2O. The H2O antisymmetric stretch was absent in n=1 and gradually increased in intensity with n. In the n=4 clusters, we found evidence for the beginning of a second solvation shell as well as the onset of an intracluster reaction that formed HONO. These clusters exhibited additional weak, broad bands between 3200 and 3400 cm-1 and two new minor photodissociation channels, loss of HONO and loss of two H2O molecules. The reaction appeared to go to completion within the n=5 clusters. The primary dissociation channel was loss of HONO, and seven vibrational bands were observed. From an analysis of the spectrum, we concluded that the n=5 cluster rearranged to form H3O+(H2O)3(HONO), i.e., an adduct of the reaction products.

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

    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.

  5. Ilyukhinite (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 • 3H2O, a New Mineral of the Eudialyte Group (United States)

    Chukanov, N. V.; Rastsvetaeva, R. K.; Rozenberg, K. A.; Aksenov, S. M.; Pekov, I. V.; Belakovsky, D. I.; Kristiansen, R.; Van, K. V.


    A new eudialyte-group mineral, ilyukhinite, ideally (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 · 3H2O, has been found in peralkaline pegmatite at Mt. Kukisvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia. It occurs as brownish orange, with vitreous luster anhedral grains up to 1 mm across in hydrothermally altered peralkaline rock, in association with aegirine, murmanite, albite, microcline, rhabdophane-(Ce), fluorite, sphalerite and molybdenite. The Mohs hardness is 5; cleavage is not observed. D meas 2.67(2), D calc 2.703 g/cm3. Ilyukhinite is optically uniaxial (-): ω = 1.585(2), ɛ = 1.584(2). The IR spectrum is given. The average chemical composition of ilyukhinite (wt %; electron microprobe, ranges given in parentheses; H2O determined by gas chromatography) is as follows: 3.07 (3.63-4.43) Na2O, 0.32 (0.28-0.52) K2O, 10.63 (10.26-10.90) CaO, 3.06 (2.74-3.22) MnO, 1.15 (0.93-1.37) FeO, 0.79 (0.51-0.89) La2O3, 1.21 (0.97-1.44) Ce2O3, 0.41 (0.30-0.56) Nd2O3, 0.90 (0.77-1.12) TiO2, 10.94 (10.15-11.21) ZrO2, 1.40 (0.76-1.68) Nb2O5, 51.24 (49.98-52.28) SiO2, 1.14 (0.89-1.37) SO3, 0.27 (0.19—0.38) Cl, 10.9(5 )H2O,-0.06-O = C1, total is 98.27. The empirical formula is H36.04(Na3.82K0.20)(Ca5.65Ce0.22La0.14Nd0.07)(Mn1.285Fe0.48)(Zr2.645Ti0.34)Nb0.31Si25.41S0.42Cl0.23O86.82. The crystal structure has been solved ( R = 0.046). Ilyukhinite is trigonal, R3 m; a = 14.1695(6) Å, b = 31.026(1) Å, V = 5394.7(7) Å3, Z = 3. The strongest XRD reflections [ d, Å (I, %) ( hkl)] are 11.44 (82) (101), 7.09 (70) (110), 6.02 (44) (021), 4.371 (89) 205), 3.805 (47) (303, 033), 3.376 (41) (131), 2.985 (100) (315, 128), 2.852 (92) (404). Ilyukhinite was named in memory of Vladimir V. Ilyukhin (1934-1982), an outstanding Soviet crystallographer. The type specimen of ilyukhinite has been deposited in the collection of the Natural History Museum, University of Oslo, Norway.

  6. Proton transfer and unimolecular decay in the low-energy-reaction dynamics of H3O+ with acetone

    International Nuclear Information System (INIS)

    Creasy, W.R.; Farrar, J.M.


    The title reaction has been studied at collision energies of 0.83 and 2.41 eV. Direct reaction dynamics have been observed at both energies and an increasingly high fraction of the total energy appears in product translation as the collision energy increases. This result is consistent with the concept of induced repulsive energy release, which becomes more effective as trajectories sample the corner of the potential energy surface. At the higher collision energy, the protonated acetone cation undergoes two unimolecular decay channels: C-C bond cleavage to CH 3 CO + and CH 4 , and C-O bond cleavagto C 3 H 5 + (presumably to allyl cation) and H 2 O. The CH 3 CO + channel, endothermic relative to ground state protonated acetone cations by 0.74 eV, appears to liberate 0.4 eV in relative product translation while the C 3 H 5 + channel, endothermic by 2.17 eV, liberates only 0.07 eV in relative translation. These results are discussed in terms of the location on the reaction coordinate and magnitudes of potential energy barriers to 1,3-hydrogen atoms shifts which must precede the bond cleavage processes

  7. A SIFT Study of the Reactions of H3O+, NO+ and O2+ with Hydrogen Peroxide and Peroxyacetic Acid

    Czech Academy of Sciences Publication Activity Database

    Španěl, Patrik; Diskin, A. M.; Wang, T.; Smith, D.


    Roč. 228, - (2003), s. 269-283 ISSN 1387-3806 R&D Projects: GA ČR GA202/03/0827; GA ČR GA203/02/0737 Institutional research plan: CEZ:AV0Z4040901 Keywords : SIFT * hydrogen peroxide * peroxyacetic acid Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.361, year: 2003

  8. Accurate prediction of H3O+ and D3O+ sensitivity coefficients to probe a variable proton-to-electron mass ratio

    Czech Academy of Sciences Publication Activity Database

    Owens, A.; Yurchenko, S. N.; Polyansky, O. L.; Ovsyannikov, R. I.; Thiel, W.; Špirko, Vladimír


    Roč. 454, č. 3 (2015), s. 2292-2298 ISSN 0035-8711 Institutional support: RVO:61388963 Keywords : molecular data * cosmological parameters * infrared * ISM * submillimetre: ISM Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.952, year: 2015

  9. A nine-dimensional ab initio global potential energy surface for the H2O+ + H2 → H3O+ + H reaction (United States)

    Li, Anyang; Guo, Hua


    An accurate full-dimensional global potential energy surface (PES) is developed for the title reaction. While the long-range interactions in the reactant asymptote are represented by an analytical expression, the interaction region of the PES is fit to more than 81 000 of ab initio points at the UCCSD(T)-F12b/AVTZ level using the permutation invariant polynomial neural network approach. Fully symmetric with respect to permutation of all four hydrogen atoms, the PES provides a faithful representation of the ab initio points, with a root mean square error of 1.8 meV or 15 cm-1. The reaction path for this exoergic reaction features an attractive and barrierless entrance channel, a submerged saddle point, a shallow H4O+ well, and a barrierless exit channel. The rate coefficients for the title reaction and kinetic isotope effect have been determined on this PES using quasi-classical trajectories, and they are in good agreement with available experimental data. It is further shown that the H2O+ rotational enhancement of reactivity observed experimentally can be traced to the submerged saddle point. Using our recently proposed Sudden Vector Projection model, we demonstrate that a rotational degree of freedom of the H2O+ reactant is strongly coupled with the reaction coordinate at this saddle point, thus unraveling the origin of the pronounced mode specificity in this reaction.

  10. A nine-dimensional ab initio global potential energy surface for the H2O+ + H2 → H3O+ + H reaction

    International Nuclear Information System (INIS)

    Li, Anyang; Guo, Hua


    An accurate full-dimensional global potential energy surface (PES) is developed for the title reaction. While the long-range interactions in the reactant asymptote are represented by an analytical expression, the interaction region of the PES is fit to more than 81 000 of ab initio points at the UCCSD(T)-F12b/AVTZ level using the permutation invariant polynomial neural network approach. Fully symmetric with respect to permutation of all four hydrogen atoms, the PES provides a faithful representation of the ab initio points, with a root mean square error of 1.8 meV or 15 cm −1 . The reaction path for this exoergic reaction features an attractive and barrierless entrance channel, a submerged saddle point, a shallow H 4 O + well, and a barrierless exit channel. The rate coefficients for the title reaction and kinetic isotope effect have been determined on this PES using quasi-classical trajectories, and they are in good agreement with available experimental data. It is further shown that the H 2 O + rotational enhancement of reactivity observed experimentally can be traced to the submerged saddle point. Using our recently proposed Sudden Vector Projection model, we demonstrate that a rotational degree of freedom of the H 2 O + reactant is strongly coupled with the reaction coordinate at this saddle point, thus unraveling the origin of the pronounced mode specificity in this reaction

  11. Selected ion flow tube (SIFT) studies of the reactions of H3O+, NO+ and O-2(+center dot) with six volatile phytogenic esters

    Czech Academy of Sciences Publication Activity Database

    Sovová, K.; Dryahina, Kseniya; Španěl, Patrik


    Roč. 300, č. 1 (2011), s. 31-38 ISSN 1387-3806 R&D Projects: GA ČR GA202/09/0800; GA ČR GA203/09/0256 Institutional research plan: CEZ:AV0Z40400503 Keywords : SIFT-MS * ion-molecule reactions * plant esters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.549, year: 2011

  12. Reactions of the selected ion flow tube mass spectrometry reagent ions H3O+ and NO+ with a series of volatile aldehydes of biogenic significance

    Czech Academy of Sciences Publication Activity Database

    Smith, D.; Chippendale, T. W. E.; Španěl, Patrik


    Roč. 28, č. 17 (2014), s. 1917-1928 ISSN 0951-4198 R&D Projects: GA ČR GA13-28882S Institutional support: RVO:61388955 Keywords : SOLID-PHASE MICROEXTRACTION * TRACE GAS- ANALYSIS * ON-FIBER-DERIVATIZATION Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.253, year: 2014

  13. Selected Ion Flow Tube, SIFT, Studies of the Reactions of H3O+, NO+ and O2+ with Eleven C10H16 Monoterpenes

    Czech Academy of Sciences Publication Activity Database

    Wang, T.; Španěl, Patrik; Smith, D.


    Roč. 228, - (2003), s. 117-126 ISSN 1387-3806 R&D Projects: GA ČR GA202/03/0827; GA ČR GA203/02/0737 Institutional research plan: CEZ:AV0Z4040901 Keywords : SIFT * terpenes * proton transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.361, year: 2003

  14. Accurate prediction of H3O+ and D3O+ sensitivity coefficients to probe a variable proton-to-electron mass ratio (United States)

    Owens, A.; Yurchenko, S. N.; Polyansky, O. L.; Ovsyannikov, R. I.; Thiel, W.; Špirko, V.


    The mass sensitivity of the vibration-rotation-inversion transitions of H316O+, H318O+, and D316O+ is investigated variationally using the nuclear motion program TROVE (Yurchenko, Thiel & Jensen). The calculations utilize new high-level ab initio potential energy and dipole moment surfaces. Along with the mass dependence, frequency data and Einstein A coefficients are computed for all transitions probed. Particular attention is paid to the Δ|k| = 3 and Δ|k - l| = 3 transitions comprising the accidentally coinciding |J, K = 0, v2 = 0+> and |J, K = 3, v2 = 0-> rotation-inversion energy levels. The newly computed probes exhibit sensitivities comparable to their ammonia and methanol counterparts, thus demonstrating their potential for testing the cosmological stability of the proton-to-electron mass ratio. The theoretical TROVE results are in close agreement with sensitivities obtained using the non-rigid and rigid inverter approximate models, confirming that the ab initio theory used in the present study is adequate.

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

    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. Herpes simplex virus 1 (HSV-1), which causes a variety of diseases, can establish lifelong latent infections from which virus can reactivate to cause recurrent disease. Latency is the most biologically interesting and clinically vexing feature of the virus. Ever since miR-H2's discovery as a viral microRNA bearing complete sequence complementarity to the mRNA for the important viral gene activator ICP0, inhibition of ICP0 expression by miR-H2 has been a major hypothesis to help explain the repression of lytic gene expression during latency. However, this hypothesis remained untested in latently infected animals. Using a miR-H2-deficient mutant virus, we found no evidence that miR-H2 represses the expression of ICP0 or other lytic genes in cells or mice infected with HSV-1. Although miR-H2 can repress ICP0 expression in transfection assays, such repression is weak. The results suggest that other mechanisms for miR-H2 activity and for the repression of lytic gene expression during latency deserve investigation. Copyright © 2017 American Society for Microbiology.

  16. A selected ion flow tube study of the reactions of H3O+, NO+ and O-2(+center dot) with seven isomers of hexanol in support of SIFT-MS

    Czech Academy of Sciences Publication Activity Database

    Smith, D.; Sovová, Kristýna; Španěl, Patrik


    Roč. 319, MAY 1 2012 (2012), s. 25-30 ISSN 1387-3806 R&D Projects: GA ČR GA203/09/0256 Institutional support: RVO:61388955 Keywords : selected ion flow tube mass spectrometry * proton transfer * ion molecule reaction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.142, year: 2012

  17. Selected ion flow tube, SIFT, studies of the reactions of H3O+, NO+ and O2 + with some biologically active isobaric compounds in preparation for SIFT-MS analyses

    Czech Academy of Sciences Publication Activity Database

    Smith, D.; Chippendale, T. W. E.; Španěl, Patrik


    Roč. 303, 2-3 (2011), s. 81-89 ISSN 1387-3806 R&D Projects: GA ČR GA202/09/0800; GA ČR GA203/09/0256 Institutional research plan: CEZ:AV0Z40400503 Keywords : SIFT-MS * ion-molecule reactions * proton transfers Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.549, year: 2011

  18. Vibrational spectroscopy of NO^+(H_2O)_n: Evidence for the intracluster reaction NO^+(H_2O)_n→H_3O^+(H_2O)_(n-2)(HONO) at n≥4


    Choi, Jong-Ho; Kuwata, Keith T.; Haas, Bernd-Michael; Cao, Yibin; Johnson, Matthew S.; Okumura, Mitchio


    Infrared spectra of mass‐selected clusters NO^+(H_2O)_n for n=1 to 5 were recorded from 2700 to 3800 cm^(−1) by vibrational predissociation spectroscopy. Vibrational frequencies and intensities were also calculated for n=1 and 2 at the second‐order Møller–Plesset (MP2) level, to aid in the interpretation of the spectra, and at the singles and doubles coupled cluster (CCSD) level energies of n=1 isomers were computed at the MP2 geometries. The smaller clusters (n=1 to 3) were complexes of H_2O...

  19. Selected ion flow tube study of the reactions of H3O+ and NO+ with a series of primary alcohols in the presence of water vapour in support of selected ion flow tube mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Španěl, Patrik; Žabka, Ján; Zymak, Illia; Smith, D.


    Roč. 31, č. 5 (2017), s. 437-446 ISSN 0951-4198 R&D Projects: GA ČR GA13-28882S; GA ČR(CZ) GA14-19693S Institutional support: RVO:61388955 Keywords : trace gas-analysis * sift-ms * breath analysis * fa-sift * ptr-ms Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.998, year: 2016

  20. A Selected Ion Flow Tube, SIFT, Study of the Reactions of H3O+, NO+ and O2+·áIons with Several N- and O-containing Heterocyclic Compounds in Support of SIFT-MS

    Czech Academy of Sciences Publication Activity Database

    Wang, T.; Smith, D.; Španěl, Patrik


    Roč. 237, č. 1 (2004), s. 167-174 ISSN 1387-3806 R&D Projects: GA ČR GA202/03/0827; GA ČR GA203/02/0737 Institutional research plan: CEZ:AV0Z4040901 Keywords : SIFT * heterocyclic s * SIFT-MS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.235, year: 2004

  1. Specific processes and scrambling in the dehydrogenation of ethane and the degenerate hydrogen exchange in the gas-phase ion chemistry of the Ni(C,H3,O)+/C2H6 couple

    Czech Academy of Sciences Publication Activity Database

    Schlangen, M.; Schwarz, H.; Schröder, Detlef


    Roč. 90, č. 5 (2007), s. 847-853 ISSN 0018-019X Institutional research plan: CEZ:AV0Z40550506 Keywords : alkoxides * C-H activation * gas-phase investigations * mass spectrometry * nicel Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.515, year: 2007

  2. A Selected Ion Flow Tube, SIFT, Study of the Ion Chemistry of H3O+, NO+ and O2+ Ions with Several Nitroalkanes in the Presence of Water Vapour

    Czech Academy of Sciences Publication Activity Database

    Dryahina, Kseniya; Polášek, Miroslav; Španěl, Patrik


    Roč. 239, č. 1 (2004), s. 57-65 ISSN 1387-3806 R&D Projects: GA ČR GA203/02/0737; GA ČR GA202/03/0827 Institutional research plan: CEZ:AV0Z4040901 Keywords : SIFT * nitropropane * nitromethane Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.235, year: 2004

  3. Ab initio electron correlated studies on the intracluster reaction of NO+ (H2O)(n) → H3O+ (H2O)(n-2) (HONO) (n = 4 and 5). (United States)

    Asada, Toshio; Nagaoka, Masataka; Koseki, Shiro


    Hydrated nitrosonium ion clusters NO(+)(H(2)O)(n) (n = 4 and 5) were investigated by using MP2/aug-cc-pVTZ level of theory to clarify isomeric reaction pathways for formation of HONO and fully hydrated hydride ions. We found some new isomers and transition state structures in each hydration number, whose lowest activation energies of the intracluster reactions were found to be 4.1 and 3.4 kcal mol(-1) for n = 4 and n = 5, respectively. These thermodynamic properties and full quantum mechanical molecular dynamics simulation suggest that product isomers with HONO and fully hydrated hydride ions can be obtained at n = 4 and n = 5 in terms of excess hydration binding energies which can overcome these activation barriers.

  4. The synthesis, spectroscopy and X-ray single crystal structure of catena-[(μ-anacardato)-copper(II)bipyridine][Cu2{(μ-O2CC6H3(o-OH)(o-C15H31)}4(NC5H5)2]. (United States)

    Malik, Mohammad Azad; O'Brien, Paul; Tuna, Floriana; Pritchard, Robin; Buchweishaija, Joseph; Kimambo, Elianaso; Mubofu, Egid B


    Hydrogenation of crude anacardic acid gave a transparent crystalline product on recrystallization. When reacted with copper nitrate in the presence of pyridine it produced green crystals of a pyridine adduct of a dimeric copper(II) anacardate with the copper acetate structure. The X-ray single crystal structures of both anacardic acid and the copper complex were determined. Magnetic studies have confirmed strong antiferromagnetic coupling between copper(II) centre in the dimer. The exchange coupling constant was determined to be J = -324 cm(-1). The EPR spectra of the polycrystalline product are consistent with spin S = 1. The zero-field splitting parameter and g tensor values are |D| = 0.36 cm(-1), g(||) = 2.36 and g(⊥) = 2.06.

  5. Matrix isolation and low temperature solid state FTIR spectroscopic study of alpha-furil


    Lopes, Susy; Gómez-Zavaglia, Andrea; Fausto, Rui


    Alpha-furil [C(4)H(3)O-C(=O)-C(=O)-C(4)H(3)O] has been isolated in argon and xenon matrices and studied by FTIR spectroscopy, supported by DFT(B3LYP)/6-311++G(d,p) calculations. The obtained spectra were fully assigned and revealed the presence in the matrices of three different conformers, all of them exhibiting skewed conformations around the intercarbonyl bond with the two C(4)H(3)O-C(=O) fragments nearly planar. The three conformers differ in the orientation of the furan rings relative to...

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

    DEFF Research Database (Denmark)

    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...

  7. Simulation of Electron and Ion Transport in Methane-Air Counterflow Diffusion Flames (United States)

    Choi, Sangkyu; Bisetti, Fabrizio; Chung, Suk Ho


    The spatial distribution of charged species in a methane-air counterflow diffusion flame is simulated with a detailed ion chemistry. The electric field induced by the distribution of charged species is calculated and compared to that obtained invoking the ambipolar diffusion assumption. The two calculations showed identical profiles for charged species and electric field. The profiles of ion mole fractions show two peaks: one near the maximum temperature and a second peak on the oxidizer side. The major ions near the maximum temperature are electron, C2H3O+ and H3O+. CHO3- and H3O+ contribute to the second peak. These profiles are quite different from those adopting a simplified three-step mechanism based solely on E-, CHO+ and H3O+, which shows only a single peak. Reaction pathway analyses showed that near the flame region, the proton is transferred by the path of CHO+ -> H3O+ -> C2H3O+ -> CHO+ in a circulating manner. In the second peak, CHO3- is produced though the pathway of E- -> O- -> OH- -> CHO3-. The sensitivity of the charged species profiles to transport properties is investigated, and it is found that the variation of charged species profiles near peak temperature is relatively small, while on the oxidizer side, it is quite sensitive to transport properties.

  8. Proton solvation and proton transfer in chemical and electrochemical processes

    International Nuclear Information System (INIS)

    Lengyel, S.; Conway, B.E.


    This chapter examines the proton solvation and characterization of the H 3 O + ion, proton transfer in chemical ionization processes in solution, continuous proton transfer in conductance processes, and proton transfer in electrode processes. Topics considered include the condition of the proton in solution, the molecular structure of the H 3 O + ion, thermodynamics of proton solvation, overall hydration energy of the proton, hydration of H 3 O + , deuteron solvation, partial molal entropy and volume and the entropy of proton hydration, proton solvation in alcoholic solutions, analogies to electrons in semiconductors, continuous proton transfer in conductance, definition and phenomenology of the unusual mobility of the proton in solution, solvent structure changes in relation to anomalous proton mobility, the kinetics of the proton-transfer event, theories of abnormal proton conductance, and the general theory of the contribution of transfer reactions to overall transport processes

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

    International Nuclear Information System (INIS)

    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, CsV 2 (H 3 O)(HPO 3 ) 4 (1), and Ba 3 V 2 (HPO 3 ) 6 (2). Both compounds were prepared by hydrothermal reactions and feature unique new structures. They both exhibit 3D complicated frameworks based on VO 6 octahedra which are connected by HPO 3 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 CsV 2 (H 3 O) (HPO 3 ) 4 (1) is a new 3,3,3,4,5-connected network with the Schläfli symbol of {4.6 2 } 2 {4 2 .6 6 .8 2 }{6 3 }{6 5 .8}. The investigations of X-ray photoelectron spectroscopy (XPS) and magnetic measurement on CsV 2 (H 3 O)(HPO 3 ) 4 suggest a +3 oxidation state of the vanadium ions in compound 1. Photocatalytic performance was evaluated by photocatalytic H 2 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. - Graphical abstract: Metal vanadium phosphites with broad absorption for photocatalytic hydrogen evolution and the degradation of methylene blue aqueous solution. - Highlights: • Two new vanadium phosphites, CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 , are reported. • CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 feature complicated 3D framework structures with different channels. • CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 exhibit strong and broad absorptions in the visible and Near IR region. • Photocatalytic properties of CsV 2 (H 3 O)(HPO 3 ) 4 and Ba 3 V 2 (HPO 3 ) 6 are investigated. • The magnetic measurement of CsV 2 (H 3 O)(HPO 3 ) 4 was performed in the temperature range of 2–300 K.

  10. On the mechanism of water cluster-ion formation in carbon dioxide

    International Nuclear Information System (INIS)

    Warneck, P.; Rakshit, A.B.


    A drift chamber mass spectrometer has been used to study the formation of water cluster-ions in carbon dioxide containing traces of water vapour. The dominant reaction sequences were identified up to the fourth generation of daughter ions starting with CO 2 + . The subsequent reaction mechanism remains uncertain and several possibilities are discussed. The final ions are H 3 O + H 2 O and H 3 O + (H 2 O) 2 . The significance of the reaction schemes to the radiation chemistry of carbon dioxide is pointed out. (orig.)

  11. Revisit the landscape of protonated water clusters H+(H2O)n with n = 10-17: An ab initio global search (United States)

    Shi, Ruili; Li, Keyao; Su, Yan; Tang, Lingli; Huang, Xiaoming; Sai, Linwei; Zhao, Jijun


    Using a genetic algorithm incorporated with density functional theory, we explore the ground state structures of protonated water clusters H+(H2O)n with n = 10-17. Then we re-optimize the isomers at B97-D/aug-cc-pVDZ level of theory. The extra proton connects with a H2O molecule to form a H3O+ ion in all H+(H2O)10-17 clusters. The lowest-energy structures adopt a monocage form at n = 10-16 and core-shell structure at n = 17 based on the MP2/aug-cc-pVTZ//B97-D/aug-cc-pVDZ+ZPE single-point-energy calculation. Using second-order vibrational perturbation theory, we further calculate the infrared spectra with anharmonic correction for the ground state structures of H+(H2O)10-17 clusters at the PBE0/aug-cc-pVDZ level. The anharmonic correction to the spectra is crucial since it reproduces the experimental results quite well. The extra proton weakens the O-H bond strength in the H3O+ ion since the Wiberg bond order of the O-H bond in the H3O+ ion is smaller than that in H2O molecules, which causes a red shift of the O-H stretching mode in the H3O+ ion.

  12. Combined use of gas chromatography and selected ion flow tube mass spectrometry for absolute trace gas quantification

    Czech Academy of Sciences Publication Activity Database

    Kubišta, Jiří; Španěl, Patrik; Dryahina, Kseniya; Workman, C. T.; Smith, D.


    Roč. 20, č. 4 (2006), s. 563-567 ISSN 0951-4198 R&D Projects: GA ČR GA202/03/0827 Institutional research plan: CEZ:AV0Z40400503 Keywords : SIFT-MS * H3O+ * NO+ * series Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.680, year: 2006

  13. Solubility of jarosite solid solutions precipitated from acid mine waters, Iron Mountain, California (United States)

    Alpers, Charles N.; Nordstrom, D. Kirk; Ball, J.W.


    Because of the common occurrence of 15 to 25 mole percent hydronium substitution on the alkali site in jarosites, it is necessary to consider the hydronium content of jarosites in any attempt at rigorous evaluation of jarosite solubility or of the saturation state of natural waters with respect to jarosite. A Gibbs free energy of 3293.5±2.1 kJ mol-1 is recommended for a jarosite solid solution of composition K.77Na.03(H3O).20Fe3(SO4)2(OH)6. Solubility determinations for a wider range of natural and synthetic jarosite solid solutions will be necessary to quantify the binary and ternary mixing parameters in the (K-Na-H3O) system. In the absence of such studies, molar volume data for endmember minerals indicate that the K-H3O substitution in jarosite is probably closer to ideal mixing than either the Na-K or Na-H3O substitution.

  14. Neutral and Ionized Hydrides in Star-forming Regions. Observations with Herschel/HIFI

    DEFF Research Database (Denmark)

    O. Benz, Arnold; Bruderer, Simon; F. van Dishoeck, Ewine


    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...

  15. Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH. (United States)

    Walrafen, George E; Douglas, Rudolph T W


    High-temperature, high-pressure Raman spectra were obtained from aqueous NaOH solutions up to 2NaOHH2O, with X(NaOH)=0.667 at 480 K. The spectra corresponding to the highest compositions, X(NaOH)> or =0.5, are dominated by H3O2-. An IR xi-function dispersion curve for aqueous NaOH, at 473 K and 1 kbar, calculated from the data of Franck and Charuel indicates that the OH- ion forms H3O2- by preferential H bonding with nonhydrogen-bonded OH groups. Raman spectra from wet to anhydrous, solid LiOH, NaOH, and KOH yield sharp, symmetric OH- stretching peaks at 3664, 3633, and 3596 cm(-1), respectively, plus water-related, i.e., H3O2-, peaks near LiOH, 3562 cm(-1), NaOH, 3596 cm(-1), and, KOH, 3500 cm(-1). Absence of H3O2- peaks from the solid assures that the corresponding melt is anhydrous. Raman spectra from the anhydrous melts yield OH- stretching peak frequencies: LiOH, 3614+/-4 cm(-1), 873 K; NaOH, 3610+/-2 cm(-1), 975 K; and, KOH, 3607+/-2 cm(-1), 773 K, but low-frequency asymmetry due to ion-pair interactions is present which is centered near 3550 cm(-1). The ion-pair-related asymmetry corresponds to the sole IR maximum near 3550 cm(-1) from anhydrous molten NaOH, at 623 K. Bose-Einstein correction of published low-frequency Raman data from molten LiOH revealed an acoustic phonon, near 205 cm(-1), related to restricted translation of OH- versus Li+, and an optical phonon, at 625 cm(-1) and tau approximately 0.05 ps, due to protonic precession and/or pendular motion. Strong H bonding between water and the O atom of OH- forms H3O2-, but the proton of OH- does not bond with H significantly. Large Raman bandwidths (aqueous solutions) are explained in terms of inhomogeneous broadening due to proton transfer in a double well. Vibrational assignments are presented for H3O2-.

  16. Waht is 'molybdic acid' or 'polymolybdic acid'?

    International Nuclear Information System (INIS)

    Tytko, K.H.; Baethe, G.; Mehmke, K.


    According to a comparative study of the literature, supplemented by well-aimed experimental investigations and equilibrium calculations, the terms 'molybdic acid' or 'polymolybdic acid', used for many substances, species, or solutions in the literature, are applicable to a species, a solution, and two solids: a) The monomeric molybdic acid, most probably having the formula MoO 2 (OH) 2 (H 2 O) 2 (= H 2 MoO 4 , aq), exists in (aqueous) solution only and never exceeds a concentration of ∼ 10 -3 M since at higher concentrations it reacts with other monomeric molybdenum(VI) species to give anionic or cationic polymers. b) A concentrated (> 0.1 M Mo VI ) aqueous molybdate solution of degree of acidification P = 2 (realized, e.g., by a solution of one of the Mo VI oxides; by any molybdate solutions whose cations have been exchanged by H 2 O + on a cation exchanger; by suitable acidification of a molybdate solution) contains 8 H 3 O + and the well-known polyanion Mo 36 O 112 (H 2 O) 16 8- exactly in the stoichiometric proportions. c) A glassy substance, obtained from an alkali metal salt-free solution prepared acording to (b), refers to the compound (H 3 O) 8 [Mo 36 O 112 (H 2 O) 16 ] · xH 2 O, x = 25 - 29. d) A solid having the ideal composition [(H 3 O)Mo 5 O 15 (OH)H 2 O · H 2 O] ∞ consists of a polymolybdate skeleton (the well-known 'decamolybdate' structure), in the tunnels of which H 3 O + and H 2 O are intercalated. The structure is very unstable if only H 3 O + cations are present, but it is enormously stabilized by a partial exchange of H 3 O + by certain alkali or alkaline earth metal cations. For the compounds MoO 3 , MoO 3 ·H 2 O, and MoO 3 · 2 H 2 O the term 'molybdic acid' is unjustified. The commercial product 'molybdic acid, ∼ 85% MoO 3 ' is the well-known polymolybdate (NH 4 ) 2 O · 4 MoO 3 with a layer structure of the polyanion. 84 refs. (author)

  17. Fabrication of oxide layer on zirconium by micro-arc oxidation: Structural and antimicrobial characteristics. (United States)

    Fidan, S; Muhaffel, F; Riool, M; Cempura, G; de Boer, L; Zaat, S A J; Filemonowicz, A Czyrska-; Cimenoglu, H


    The aim of this study was to cover the surfaces of zirconium (Zr) with an antimicrobial layer for biomedical applications. For this purpose, the micro-arc oxidation (MAO) process was employed in a sodium silicate and sodium hydroxide containing base electrolyte with and without addition of silver acetate (AgC 2 H 3 O 2 ). In general, synthesized MAO layers were composed of zirconium oxide (ZrO 2 ) and zircon (ZrSiO 4 ). Addition of AgC 2 H 3 O 2 into the base electrolyte caused homogenous precipitation of silver-containing particles in the MAO layer, which exhibited excellent antibacterial efficiency against methicillin-resistant Staphylococcus aureus (MRSA) as compared to the untreated and MAO-treated Zr. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    DEFF Research Database (Denmark)

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


    . 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...... 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...

  19. AFOSR/AFRPL Chemical Rocket Research Meeting, Abstracts and Agenda. Includes Abstracts of AFOSR Sponsored Research on Diagnostics of Reacting Flow, 18-21 March 1985, Lancaster, California (United States)


    IP’s) and energetic internal plasticizers (EIP’s). The ethylene glycol malonate (EGM).prepolymer system has been chosen as our model system because of...2,6-(CH3 ) 2C6H3, .- oL-biphenyl, SiMe 3 , SiPh 3 , CPh 3 , and neopentyl ) and (n-CsMes) 2V lead to (Figure 1) either (n-CsMe 5)2VNR or (r-CsMes)aVNs

  20. Hydroniumjarosite, (H.sub.3./sub.O).sup.+./sup.Fe.sub.3./sub.(SO.sub.4./sub.).sub.2./sub.(OH).sub.6./sub., from Cerros Pintados, Chile: single-crystal X-ray diffraction and vibrational spectroscopic study

    Czech Academy of Sciences Publication Activity Database

    Plášil, Jakub; Škoda, R.; Fejfarová, Karla; Čejka, J.; Kasatkin, A.V.; Dušek, Michal; Talla, D.; Lapčák, L.; Machovič, V.; Dini, M.


    Roč. 78, č. 3 (2014), s. 535-547 ISSN 0026-461X R&D Projects: GA ČR GP13-31276P Grant - others:AV ČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : hydroniumjarosite * H3O + * crystal structure * vibrational spectroscopy * X-ray diffraction Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.026, year: 2014

  1. 21 CFR 184.1185 - Calcium acetate. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium acetate. 184.1185 Section 184.1185 Food and... Substances Affirmed as GRAS § 184.1185 Calcium acetate. (a) Calcium acetate (Ca (C2H3O2)2, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be...

  2. Stereoretentive formylation of (S)-proline

    DEFF Research Database (Denmark)

    Temizsoy, Mehmet; Sethi, Waqas; Reinholdt, Anders


    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...

  3. Mechanism of intercalation in protonic conductors: case of HUP (H3OUO2PO4, 3H2O) and the corresponding xerogel [(UO2)sub(1.5-x) PO4Hsub(2x),2H2O

    International Nuclear Information System (INIS)

    Colomban, P.; Pham Thi, M.


    Intercalation of acetone alkylammonium, methylviologen and cobalticinium ions in HUP framework (H 3 OUO 2 PO 4 .3H 2 O) have been studied with different methods (IR and Raman spectroscopies, X-ray diffraction, DSC and scanning electron microscopy). Various reactions have been pointed out: i.e. proton transfer from H 3 O + to PO 4 3- , ionisation of cobaltocene into cobalticinium. Species orientation is discussed and its influence on conductivity and phase transitions [fr

  4. Unipolar Electric Machines with Liquid-Metal Current Pickup, (United States)


    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

  5. Synthesis, properties, structure and thermochemistry of hexa-aqua-tris (N,N-dimethylformamide) lanthanide tri fluoro methane sulfonates

    International Nuclear Information System (INIS)

    Araujo Melo, D.M. de.


    Addition compounds between several lanthanide salts and dimethylformamide (DMF) have been described in the literature. This thesis reports the synthesis and characterization of the compounds of general composition Ln (C H 3 SO 3 ) 3 . 3 DMF.6 H 3 O) (Ln = La - Ho) and Ln (C H 3 SO 3 ) 3 DMF.6 H 2 O (Ln = Er - Lu). The structure of the neodymium compound, isomorphous with the series, is also described. The enthalpy variations were determined by solution calorimetry. (author)

  6. Application of extraction of gallium molybdotungstate HPA for their investigation in solutions and gallium determination

    International Nuclear Information System (INIS)

    Kol'tsova, E.G.; Vakulich, A.N.; Tsyganok, L.P.


    Extraction of gallium molybdotungstate heteropolyacids and their associates with a row of triphenylmethane dyes, use of extraction for study of complexing in Mo 6 -W 6 -Ga 3+ -H 3 O + system are investigated. Research of optimal analytical states and development of extraction spectrophotometric methods of gallium determination are done. It is shown that increase of Mo 6 part in heteropolyanion improves solvation interaction of heteropolyacids with organic solvents elevating extraction properties of polyanion [ru

  7. Microscopic dynamics of charge separation at the aqueous electrochemical interface


    Kattirtzi, John A.; Limmer, David T.; Willard, Adam P.


    We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water-metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali-halide pair, Na$^+$I$^-$, or classical ions, and the products of water autoionization, H$_3$O$^+$OH$^-$, or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water...

  8. Analytical imaging studies of the migration of degraded orpiment, realgar, and emerald green pigments in historic paintings and related conservation issues

    NARCIS (Netherlands)

    Keune, K.; Mass, J.; Mehta, A.; Church, J.; Meirer, F.


    Yellow orpiment (As2S3) and red–orange realgar (As4S4) photo-degrade and the nineteenth-century pigment emerald green (Cu(C2H3O2)2·3Cu(AsO2)2) degrades into arsenic oxides. Because of their solubility in water, arsenic oxides readily migrate and are found throughout the multi-layered paint system.

  9. Synthesis, Structural Characterization, Antimicrobial Activity, and In Vitro Biocompatibility of New Unsaturated Carboxylate Complexes with 2,2′-Bipyridine

    Directory of Open Access Journals (Sweden)

    Gina Vasile Scăețeanu


    Full Text Available The synthesis, structural characterization, cytotoxicity, and antimicrobial properties of four new complexes formed by employing acrylate anion and 2,2′-bipyridine are reported herein. X-ray crystallography revealed the trinuclear nature of [Mn3(2,2′-bipy2(C3H3O26] (1, meanwhile complexes with general formula [M(2,2′-bipy(C3H3O22(H2Ox]∙yH2O ((2 M: Ni, x = 1, y = 0; (3 M: Cu, x = 1, y = 0; (4 M: Zn, x = 0, y = 1; 2,2′-bipy: 2,2′-bipyridine; C3H3O2: acrylate anion were shown to be mononuclear. The lowest minimum inhibitory concentration (MIC of 128 μg mL−1 was recorded for all four tested complexes against Candida albicans, for complex (3 against Escherichia coli, and for complex (4 against Staphylocococcus aureus. Compounds (3 and (4 were also potent efflux pumps activity inhibitors (EPI, proving their potential for use in synergistic combinations with antibiotics. Complexes (1–(4 revealed that they were not cytotoxic to HCT-8 cells. They also proved to interfere with the cellular cycle of tumour HCT-8 cells by increasing the number of cells found in the S and G2/M phases. Taken together, these results demonstrate the potential of zinc and copper complexes for use in the development of novel antimicrobial and anti-proliferative agents.

  10. Structural and spectroscopic features of proton hydrates in the crystalline state. Solid-state DFT study on HCl and triflic acid hydrates (United States)

    Vener, M. V.; Chernyshov, I. Yu.; Rykounov, A. A.; Filarowski, A.


    Crystalline HCl and CF3SO3H hydrates serve as excellent model systems for protonated water and perfluorosulphonic acid membranes, respectively. They contain characteristic H3O+, H5О+2, H7О+3 and H3O+(H2O)3 (the Eigen cation) structures. The properties of these cations in the crystalline hydrates of strong monobasic acids are studied by solid-state density function theory (DFT). Simultaneous consideration of the HCl and CF3SO3H hydrates reveals the impact of the size of a counter ion and the crystalline environment on the structure and infrared active bands of the simplest proton hydrates. The H7O+3 structure is very sensitive to the size of the counter ion and symmetry of the local environment. This makes it virtually impossible to identify the specific features of H7O+3 in molecular crystals. The H3O+ ion can be treated as the Eigen-like cation in the crystalline state. Structural, infrared and electron-density features of H5О+2 and the Eigen cation are virtually insensitive to the size of the counter ion and the symmetry of the local crystalline environment. These cations can be considered as the simplest stable proton hydrates in the condensed phase. Finally, the influence of the Grimme correction on the structure and harmonic frequencies of the molecular crystals with short (strong) intermolecular O-H···O bonds is discussed.

  11. Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

    KAUST Repository

    Kim, Daesang


    Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane-oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH+O⇌HCO+ +E- and to the main CH consumption reaction CH+O2 ⇌O+HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ +E- →products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH-, and O-) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the

  12. Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

    KAUST Repository

    Kim, Daesang; Rizzi, Francesco; Cheng, Kwok Wah; Han, Jie; Bisetti, Fabrizio; Knio, Omar Mohamad


    Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane-oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH+O⇌HCO+ +E- and to the main CH consumption reaction CH+O2 ⇌O+HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ +E- →products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH-, and O-) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the

  13. PMR investigation of configuration and mobility of H5O2+ ions in certain tungsten heteropolyacid hexahydrates

    International Nuclear Information System (INIS)

    Chuvaev, V.F.; Barash, A.B.


    PMR-method of wide bands has been used to investigate hexahydrates of tungsten typical heteropolyacids (HPA): H 3 PW 12 O 40 x6H 2 O, H 4 SiW 12 O 40 x6H 2 O, H 5 BW 12 O 40 x6H 2 O. The results are considered from the viewpoint of existing ideas on formation of H 5 O 2+ diaquohydrogen ions in the HPA structure. SoMe problems of stabilization of low-level hydrates of tungsten and molybdenum HPA are considered as well. The data of PMR low-temperature (80K) spectra have been used to identify the H 3 O + ions, H 2 O mole-- cules and small number of free protons in the investigated HPA. Taking this into account the H 5 O 2+ under the conditions of solid lattice is characterized as static distribution of proton between two molecules of the water of H 3 O + xH 2 O group. Dependence of the PMR spectra on temperature detects two transition regions, caused by mobility of the H 5 O 2+ elements. In the region of first transition (up to 250 K) the H 3 O + xH 2 O static configuration became dynamical, because of quick proton fluctuation along the 0...0 bond and librations of the H 2 O molequles. Then, higher than 250K, the H 5 O 2+ motion became more isotopic and then diffusion. Dynamical state of the H 5 O 2+ in H 3 PW 12 O 40 x6H 2 O and H 4 SiW 12 O 40 x6H 2 O hexahydrates in the wide temperature range is of limited nature, caused by specific of the H 5 O 2+ localizetion in the HPA structure

  14. Topologically and geometrically flexible structural units in seven new organically templated uranyl selenates and selenite-selenates (United States)

    Gurzhiy, Vladislav V.; Kovrugin, Vadim M.; Tyumentseva, Olga S.; Mikhaylenko, Pavel A.; Krivovichev, Sergey V.; Tananaev, Ivan G.


    Single crystals of seven novel uranyl oxysalts of selenium with protonated methylamine molecules, [C2H8N]2[(UO2)(SeO4)2(H2O)] (I), [C2H8N]2[(UO2)2(SeO4)3(H2O)] (II), [C4H15N3][H3O]0.5[(UO2)2(SeO4)2.93(SeO3)0.07(H2O)](NO3)0.5 (III), [C2H8N]3[H5O2][(UO2)2(SeO4)3(H2O)2]2(H2O)5 (IV), [C2H8N]2[H3O][(UO2)3(SeO4)4(HSeO3)(H2O)](H2SeO3)0.2 (V), [C4H12N]3[H3O][(UO2)3(SeO4)5(H2O)] (VI), and [C2H8N]3(C2H7N)[(UO2)3(SeO4)4(HSeO3)(H2O)] (VII) have been prepared by isothermal evaporation from aqueous solutions. Their crystal structures have been solved by direct methods and their uranyl selenate and selenite-selenate units investigated using black-and-white graphs from the viewpoints of topology of interpolyhedral linkages and isomeric variations. The crystal structure of IV is based upon complex layers with unique topology, which has not been observed previously in uranyl selenates. Investigations of the statistics and local distribution of the U-Obr-Se bond angles demonstrates that shorter angles associate with undulations, whereas larger angles correspond to planar areas of the uranyl selenite layers.

  15. Ion Composition of Comet 19P/Borrelly as Measured by the PEPE Ion Mass Spectrometer on DS1 (United States)

    Nordholt, J. E.; Reisenfeld, D. B.; Wiens, R. C.; Gary, P.


    Cometary compositions are of great interest because they hold important clues to the formation of the outer solar system, and to the sources of volatiles in the solar system, including the terrestrial planets. In order to understand the primordial compositions of cometary nuclei, it is important to also understand their evolution, as many of the comets most accessible to spacecraft are highly evolved. It is also important to understand the ion and neutral chemistry that occurs in the coma surrounding the nucleus if the coma ion composition is to be used to determine the original composition of the nucleus. Deep Space One (DS1) was only the second spacecraft, after Giotto, to use an ion mass-resolving instrument to explore cometary coma compositions in-situ, which it did during the flyby of Comet Borrelly on September 22, 2001. Borrelly is significantly more evolved than Halley. In addition, the encounter occurred at a significantly greater distance from the sun (1.36 AU vs 0.9 AU for Giotto at Halley). The Plasma Experiment for Planetary Exploration (PEPE) on board DS1 was capable of resolving electron and ion energy, angle of incidence, and ion mass composition. The PEPE ion data from the seven minutes surrounding closest approach (2171 km) have been extensively analyzed. The instrument response was modeled using SIMION and TRIM codes for all of the major species through 20 AMU plus CO (at its operating voltage PEPE was very insensitive to heavier molecules). Chi-squared minimization analysis is being carried out to determine the best fit and the uncertainties. Preliminary results for the predominant heavy ions are OH+ at (72 +/- 9)% of the total water-group ion density, H2O+ at (25 +/- 7)%, CH3+ at (5 +/- 3)%, and O+ at (4 +/- 5)%. Uncertainties are quoted at the 90% confidence level. Comparison with reported Halley compositions from Giotto shows that Borrelly clearly has a lower H3O+ abundance (< 9%), consistent with a more evolved comet. The presence of

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

    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 Mg 2 H 6 (H 3 O)(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.

  17. 6-Methoxy-1-(4-methoxyphenyl-1,2,3,4-tetrahydro-9H-β-carbolin-2-ium acetate

    Directory of Open Access Journals (Sweden)

    Mohd Mustaqim Rosli


    Full Text Available In the title compound, C19H21N2O2+·C2H3O2−, the 1H-indole ring system is essentially planar [maximum deviation = 0.0257 (14 Å] and forms a dihedral angle of 87.92 (7 Å with the benzene ring attached to the tetrahydropyridinium fragment. The tetrahydropyridinium ring adopts a half-chair conformation. In the crystal, cations and anions are linked by interionic N—H...O, C—H...O and C—H...N hydrogen bonds into chains along the a axis.

  18. H2O-induced trigonal-to-tetrahedral transition in boron zeolites

    International Nuclear Information System (INIS)

    Fois, E.; Gamba, A.; Trudu, F.; Tabacchi, G.


    The behaviour of a protonated boron-containing zeolite at intermediate hydration degree has been investigated by means of periodic DFT approaches. Results of a combined room-temperature Car-Parrinello molecular dynamics blue-moon path sampling simulation indicate that, in the line with experimental findings, the BO 3 /Si-OH acid site typical of dry samples is converted to a hydrated H 3 O + hydrogen bonded to tetrahedral BO 4 - at moderate water content (four H 2 O per B site) with an activation free barrier of the order of few k T.

  19. Ion Irradiation of Sulfuric Acid: Implications for its Stability on Europa (United States)

    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.

  20. An introduction to radiation induced degradation of biological molecules in aqueous solutions

    International Nuclear Information System (INIS)

    Lal, Manohar


    Radiation chemistry of aqueous systems is the chemistry of H, OH, e aq - , H 3 O + and H 2 O * formed when a solute in aqueous solutions is exposed to ionising radiation. The pulse radiolysis technique has helped in the production, the detection and understanding of the reactions of primary species with solutes. A great deal of data on radiation biochemical studies e.g. degradation of DNA, its constituents and their protection, radiation protection and sensitisation, generation of superoxide ion and their reactions has already been reported but a great deal still needs to be done for the understanding of radiation biology. (author). 12 refs

  1. Individual extraction constants of some univalent cations in the two-phase water-phenyltrifluoromethyl sulfone system

    International Nuclear Information System (INIS)

    Makrlik, E.


    From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M + (aq) + Cs + (org) ↔ M + (org) + Cs + (aq) taking place in the two-phase water-phenyltrifluoromethyl sulfone (abbrev. FS 13) system (M + Li + , H 3 O + , Na + , NH 4 + , Ag + , Tl + , K + , Rb + ; aq = aqueous phase, org FS 13 phase) were evaluated. Furthermore, the individual extraction constants of the M + cations in the mentioned two-phase system were calculated; they were found to increase in the series of Li + 3 O + + 4 + + + + + + . (author)

  2. Cadmium poisoning of oxygen reduction on platinum electrode in potassium hydroxide (United States)

    Miller, R. O.


    Experiment with a rotating disk and ring apparatus showed no poisoning by cadmium in 8.5 M KOH, alone or with Cl(-) or CO3(=). Poisoning does not occur either in 0.1 M KOH supernatant at CdO, but a partially reversible poisoning results from .0001 M CdCl2 and traces of fatty acid are present. Evidence indicates that the catastrophic poisoning affects the four-electron O2 reduction more than it does the one-electron H3O(+) discharge.

  3. Half -sand wish ruthenium complexes of heterocyclic-dithio carboxylato ligands

    International Nuclear Information System (INIS)

    El-khateeb, M.; Al-Noaimi, M.; Harb, M.; Gorls, H.; Weigand, W.


    The heterocyclic-dithio carboxylato complexes Cp Ru(PPh 3 )(κ 2 S,S-S 2 C-h et) [h et= 2-C 4 H 3 O (1), 2-C 4 H 3 S (2), 1-C 4 H 8 N (3)] are obtained by the reaction of the ruthenium chloride, Cp Ru(PPh 3 ) 2 CI, with the anions, h et-CS 2 . The X-ray structure of Cp Ru(PPh 3 )(κ 2 S, S-S 2 C-1- C 4 H 8 N) (3) is determined by single crystal X-ray diffraction.

  4. Evaluation of B3LYP, X3LYP, and M06-class density functionals for predicting the binding energies of neutral, protonated, and deprotonated water clusters


    Bryantsev, Vyacheslav S.; Diallo, Mamadou S.; van Duin, Adri C. T.; Goddard, William A., III


    In this paper we assess the accuracy of the B3LYP, X3LYP, and newly developed M06-L, M06-2X, and M06 functionals to predict the binding energies of neutral and charged water clusters including (H_2O)_n, n = 2−8, 20), H_3O+(H_2O_)n, n = 1−6, and OH−(H_2O)_n, n = 1−6. We also compare the predicted energies of two ion hydration and neutralization reactions on the basis of the calculated binding energies. In all cases, we use as benchmarks calculated binding energies of water clusters extrapolate...

  5. Studies of gas phase ion/molecule reactions by Fourier transform ion cyclotron resonance mass spectrometry

    International Nuclear Information System (INIS)

    Kleingeld, J.C.


    An important field in which Fourier-transform ion cyclotron resonance has useful applications is that of gas phase ion chemistry, the subject of this thesis. First, the general picture of ion-molecule reactions in the gas phase is discussed. Next, some positive ion-molecule reactions are described, whereas the remaining chapters deal with negative ion-molecule reactions. Most of these studies have been performed using the FT-ICR method. Reactions involving H 3 O - and NH 4 - ions are described whereas the other chapters deal with larger organic complexes. (Auth.)

  6. New NMR method for measuring the difference between corresponding proton and deuterium chemical shifts: isotope effects on exchange equilibria

    International Nuclear Information System (INIS)

    Saunders, M.; Saunders, S.; Johnson, C.A.


    A convenient and accurate method is described for measuring the difference between a proton frequency and the corresponding deuterium frequency in its deuterated analogue relative to a reference system by using the deuterium lock in a Fourier-transform NMR spectrometer. This measurement is a sensitive way of measuring equilibrium isotope effects for hydrogen-deuterium exchange. A value of 1.60 per H-D pair is obtained for the equilibrium 2H 3 O + + 3D 2 O in equilibrium 2D 3 O + + 3H 2 O at 30 0 C in aqueous perchloric acid (HClO 4 ). 7 references, 2 tables

  7. rac-tert-Butyl{2-hydroxy-2-[4-hydroxy-3-(hydroxymethylphenyl]ethyl}azanium acrylate

    Directory of Open Access Journals (Sweden)

    Wenju Liu


    Full Text Available The title salt, C13H22NO3+·C3H3O2−, comprises one salbutamol cation and an acrylate anion. The acrylate anion is linked to the salbutamol cation via an O—H...O and an N—H...O hydrogen bond. The C=C group of the acrylate anion is disordered over two positions, with refined site occupancies of 0.812 (7 and 0.188 (7. The crystal structure is stabilized by N—H...O and O—H...O hydrogen-bonding interactions.

  8. Advanced Concepts of Naval Engineering Maintenance Training. Volume 2. Appendix F (United States)


    maintenance instruction, the Hagan Automatic Boiler Control (ABC) course. These job requirements also included the tasks, skills, and knowledges for all...Pressure 1 3/4 NAVTRAEQÜIPCEN 74-C-0151-1 TABLE OF CONTENTS VOLUME II OF II APPENDIX F Page Hagan Automatic Boiler Controls Systems (FAS) 6...a c a ■* w ■H u 0 M « s? u ’• B n J-riH 3 o c 0 hhO a a o -i •H -I 0 -H 9J ■ a a oi « C -a u <rl « vi) •a - 8 ai >> u u

  9. Kinetics of proton transport in water

    DEFF Research Database (Denmark)

    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...... are brought into the framework of quantum mechanical PT theory in condensed media. Both the nature of the elementary act and the reaction coordinates are, however, different for the two types of PT clusters. The corresponding rate constants are calculated and compared with MD simulations. Within the framework...

  10. Insight into the local magnetic environments and deuteron mobility in jarosite (AFe3(SO4)2(OD)6, A = K, Na, D3O) and hydronium alunite ((D3O)Al3(SO4)2(OD,OD2)6), from variable temperature 2H MAS NMR spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Heinmaa, Ivo; Samoson, Ago


    to the different temperature dependence of their isotropic shifts. An activation energy of 6.3(4) kJ/mol is determined for the D3O+ motion in the isostructural compound D3OAl3(SO4)2(OD)6. Our NMR results support theories that ascribes the spin glass behavior of (H3O)Fe3(SO4)2(OD)6 is to disorder of the D3O+ ion...... and/or a less distorted Fe coordination environment. No sign of proton transfer reactions from the D3O+ ion to the framework is observed....

  11. Electrochemical behaviour of the Eu3+/Eu2+ system in propionic media studied by cyclic chrono potentiometry

    International Nuclear Information System (INIS)

    Brotto, M.E.


    The electrochemical behaviour of the Eu 3 + / Eu 2 + system in propionic media was studied by means of current reversal chrono potentiometry and cyclic chrono potentiometry. Sodium perchlorate was employed as supporting electrolyte. The experiments were carried out at (25.0 ± 0.1) 0 C. The studied variables were the concentration of the electro active species, the composition of the solution and the current density. The cyclic chrono potentiometry results reveal that the charge transfer reaction is followed by the (H 3 O) + ion assisted irreversible catalytic reaction in which the Eu 3 + species is regenerated. (author)

  12. Construction of three metal-organic frameworks based on multifunctional T-shaped tripodal ligands, H3PyImDC

    KAUST Repository

    Jing, Xuemin; Meng, He; Li, Guanghua; Yü , Yang; Huo, Qisheng; Eddaoudi, Mohamed; Liu, Yunling


    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

  13. Analysis of trace gases at ppb levels by proton transfer reaction mass spectrometry (PTR-MS)

    International Nuclear Information System (INIS)

    Lindinger, W.; Hansel, A.


    A proton transfer reaction mass spectrometry (PTR-MS) system has been developed which allows for on-line measurements of trace gas components with concentrations as low as 1 ppb. The method is based on reactions of H 3 O + ions, which perform non-dissociative proton transfer to most of the common organic trace constituents but do not react with any of the components present in clean air. Examples of medical information obtained by means of breath analysis, of environmental trace analysis, and examples in the field of food chemistry demonstrate the wide applicability of the method. (Authors)

  14. Studies of layered uranium(VI) compounds. I. High proton conductivity in polycrystalline hydrogen uranyl phosphate tetrahydrate

    International Nuclear Information System (INIS)

    Howe, A.T.; Shilton, M.G.


    Hydrogen uranyl phosphate tetrahydrate HUO 2 PO 4 .4H 2 O has a high proton conductivity. The ac conductivity was 0.4 ohm -1 m -1 at 290 0 K measured parallel to the faces of sintered disks of the compound. The activation energy was found to be 31 +- 3 kJ mole -1 . The values of conductivity were between 3 and 10 times lower when measured perpendicular to the disk faces due to preferred orientation of the plate-like crystals. Both the powder and sintered disks are stable in air and insoluble in phosphoric acid solution of pH 2.5. Experiments are described which enable possible grain boundary contributions to the conductivity to be determined in such hydrates. The extrinsic grain boundary contribution to the conductivity was found to be small from experiments in which the pH in a solution cell was varied. The abnormally high bulk H + conductivity thus inferred is attributed primarily to the high concentration of H + , which exists as H 3 O + in the interlamellar hydrogen-bounded network. A Grotthus-type mechanism of conduction is proposed which involves intermolecular transfer steps (hopping) and intramolecular transfer steps, in comparable numbers, the former facilitated by the high concentration of H 3 O + ions in the structure, and the latter most likely facilitated by the high concentration of H-bond vacancies. 8 figures, 1 table

  15. Electrochemical study in the molten sodium acid sulphate - potassium acid sulphate eutectic

    International Nuclear Information System (INIS)

    Le Ber, F.


    The general properties of the NaHSO 4 - KHSO 4 molten eutectic resemble those of neutral sulphates and those of concentrated H 2 SO 4 . We have been able to show the existence in solution of the ions HSO - 4 SO 2- 4 , and H 3 O + , these last being formed by the action of the HSO - 4 ions on dissolved H 2 O. The electro-active zone with a polished platinum electrode is limited in oxidation by the ions H 3 O + and SO 2- 4 , and in reduction by the protons of HSO - 4 . We have compared the electro-active zones obtained with different electrodes (Ag-Au-graphite-mercury). We have considered the dissolution of a few metallic oxides and halides. This work shows the role as O 2- ion acceptors of HSO - 4 ions. We have undertaken an electro-chemical study of a few oxido-reduction Systems: H + / H 2 , Ag↓ / Ag (1), the vanadium and uranium Systems, those of mercury Hg↓ / Hg 2- 2 and of gold Au/Au 3+ , then of the attack by the solvent of a few common metals such as aluminium, iron, copper and nickel. The study of silver Systems has made it possible to obtain the solubility products of AgCl and AgBr and to consider the possibility of coulometric titration Cl - ions with Ag + ions. We have shown the existence of various chemical species of vanadium which may exist in the molten eutectic. (author) [fr

  16. Photoionization in Ultraviolet Processing of Astrophysical Ice Analogs at Cryogenic Temperatures (United States)

    Woon, David E.


    Two recent experimental studies have demonstrated that amino acids or amino acid precursors are generated when astrophysical ice analogs are subjected to ultraviolet (UV) irradiation at cryogenic temperatures. Understanding the complete phenomenology of photoprocessing is critical to elucidating chemical reaction mechanisms that can function within an ice matrix under very cold conditions. Pushing beyond the much better characterized study of photolytic dissociation of chemical bonds through electronic excitation, this work explored the ability of UV radiation present in the interstellar medium to ionize small molecules embedded in ices. Quantum chemical calculations, including bulk solvation effects, were used to study the ionization of hydrogen (H2), water, and methanol (CH3OH) bound in small clusters of water. Ionization potentials were found to be much smaller in the condensed phase than in the gas phase; even a small cluster can account for large changes in the ionization potentials in ice, as well as the known formation of an OH--H3O+ pair in the case of H2O photoionization. To gauge the impact of photoionization on subsequent grain chemistry, the reaction between OH and CO in the presence of H3O+ was studied and compared with the potential energy surface without hydronium present, which is relevant to chemistry following photolysis. The differences indicate that the reaction is somewhat more likely to proceed to products (H + CO2) in the case of photoionization.

  17. Fabrication of oxide layer on zirconium by micro-arc oxidation: Structural and antimicrobial characteristics

    International Nuclear Information System (INIS)

    Fidan, S.; Muhaffel, F.; Riool, M.; Cempura, G.; Boer, L. de; Zaat, S.A.J.; Filemonowicz, A. Czyrska -; Cimenoglu, H.


    The aim of this study was to cover the surfaces of zirconium (Zr) with an antimicrobial layer for biomedical applications. For this purpose, the micro-arc oxidation (MAO) process was employed in a sodium silicate and sodium hydroxide containing base electrolyte with and without addition of silver acetate (AgC 2 H 3 O 2 ). In general, synthesized MAO layers were composed of zirconium oxide (ZrO 2 ) and zircon (ZrSiO 4 ). Addition of AgC 2 H 3 O 2 into the base electrolyte caused homogenous precipitation of silver-containing particles in the MAO layer, which exhibited excellent antibacterial efficiency against methicillin-resistant Staphylococcus aureus (MRSA) as compared to the untreated and MAO-treated Zr. - Highlights: • Micro-arc oxidation process was applied on zirconium in an electrolyte containing silver acetate. • Silver incorporated in the oxide layer in the form of nanoparticles. • 0.45 wt.% silver incorporation provided excellent antibacterial activity.

  18. Nature of strontium extraction by synergistic mixtures of chlorinated cobalt dicarbollide and polyethers

    International Nuclear Information System (INIS)

    Smirnov, I.V.; Stoyanov, E.S.; Vorob'eva, T.P.


    Extraction of strontium by synergistic mixtures of chlorinated cobalt dicarbollide (DCC) with different polyethers was studied. In the acidic media the distribution coefficients (D(Sr)) decreases in the order 15-crown-5 > PEG-400 > 18-crown-6 and does not correspond to the row of constants stability of the strontium complexes with these polyethers. When passing to the salt media (Li and Na nitrates) the row of D(Sr) is changed: PEG-400 > 18 crown 6 > 15 crown 5. IR-spectroscopy study has shown that in synergistic mixtures the proton forms [H 5O2 + .PEG], [H 5O2 + .(15-crown-5)2] and [H 3 O + .(18 crown 6)] cations, which are exchange on Sr 2+ resulting to formation [Sr 2+ .PEG], [Sr 2+ .(15-crown-5)2] and [Sr 2+ .(18-crown-6)(H 2 O)n] cations correspondingly. The PEG-400 is the best among polyethylene glycols, since its all six COC groups and two even more active OH groups complete the first co-ordination sphere of Sr 2+ . Extremely low extractability of Sr 2+ from acidic media in the presence of 18-crown-6 as compared with 15-crown-5 is mainly caused by the high stability of the [H 3 O + .(18-crown-6)] cation that is responsible for less extractable hydrated Sr complex formation. (author)

  19. Evolution of charged species in propane/air flames: mass-spectrometric analysis and modelling

    International Nuclear Information System (INIS)

    Rodrigues, J M; Agneray, A; Jaffrezic, X; Bellenoue, M; Labuda, S; Leys, C; Chernukho, A P; Migoun, A N; Cenian, A; Savel'ev, A M; Titova, N S; Starik, A M


    Experimental and modelling studies of ion formation during combustion of propane/air mixtures are presented. The positive and negative ions mass/charge spectra in propane/air stoichiometric flame at atmospheric pressure are recorded in the range from 0 to 512 atomic mass units. The C 2 H 3 O + and HCO 2 - ions are found to be the most abundant ionic species in the flame front region. By increasing the distance from the flame front the ion composition changes significantly. In the burnt gas region the H 3 O + , NO + , CO 3 - , HCO 3 - ions are found to be the major charged species. To explain the experimental results the extended kinetic model describing the ion formation in flame and in the extraction system of the mass-spectrometer as well as ion-soot interaction is developed. It is shown that the ionic clusters, which are observed experimentally, form during the adiabatic expansion in the extraction system, and the presence of soot particles may change the total positive and negative ion concentrations in the gas phase

  20. Thermodynamics of Minerals Stable Near the Earth's Surface

    International Nuclear Information System (INIS)

    Navrotsky, Alexandra


    OAK B262 Research and Education Activities We are working on developing calorimetric techniques for sulfide minerals. We have completed calorimetric studies of (Na, K, H3O) jarosites, of Na and K jarosite -alunite solid solutions, and of Cr6+ - containing jarosites. We are now working on phases containing As and Pb. These studies are important to issues of heavy metal pollution in the environment. A number of postdocs, graduate students, and undergrads have participated in the research. We have active collaboration with Dirk Baron, faculty at California State University, Bakersfield. In a collaboration with Peter Burns, Notre Dame University, we are working on thermochemistry of U6+ minerals. Navrotsky has participated in a number of national workshops that are helping to define the interfaces between nanotechnology and earth/environmental science. Major Findings Our first finding on uranyl minerals shows that studtite, a phase containing structural peroxide ion, is thermodynamically unstable in the absence of a source of aqueous peroxide ion but is thermodynamically stable in contact with a solution containing peroxide concentrations expected for the radiolysis of water in contact with spent nuclear fuel. This work is in press in Science. We have a consistent thermodynamic data set for the (Na, K, H3O) (Al, Fe) jarosite, alunite minerals and for Cr6+ substituting for S6+ in jarosite. The latter phases represent one of the few solid sinks for trapping toxic Cr6+ in groundwater. Contributions within Discipline Better understanding of thermodynamic driving for and constraints on geochemical and environmental processes

  1. Margaritasite: a new mineral of hydrothermal origin from the Pena Blanca uranium district, Mexico. (United States)

    Wenrich, K.J.; Modreski, P.J.; Zielinski, R.A.; Seeley, J.L.


    Margaritasite, (Cs,K,H3O)2(UO2)2V2O8.nH2O (where Cs > K, H3O and n approx 1), a 10.514, b 8.425, c 7.25 A, beta 106.01o, P21/a, Z = 2, is a newly recognized uranium ore mineral named for the Margaritas deposit, Pena Blanca uranium district, Chihuahua, Mexico, at which it was discovered. A Cs-rich analogue of carnotite, margaritasite is the natural equivalent of synthetic Cs-uranyl vanadate (A.M. 43- 799, 50-825). A fine-grained yellow mineral, it is most easily distinguished from carnotite by XRD; X-ray powder patterns (CuKalpha radiation) show that the (001) reflection of margaritasite lies at 12.7o (2theta ), while that of carnotite is found at 13.8o (2theta ). The shift of the (001) reflection in margaritasite reflects the structural changes caused when Cs occupies the sites filled by K in carnotite. Synthesis experiments indicate that margaritasite also differs from carnotite in a higher-T hydrothermal origin. Chemical analyses and XRD data for margaritasite and synthetic Cs- carnotite, and chemical analyses for rocks from Sierra Pena Blanca and vicinity, are tabulated.-J.A.Z.

  2. Characterization of a meso-chiral isomer of a hexanuclear Cu(II) cage from racemization of the L-alanine Schiff base. (United States)

    Rajesh, Chinnaiyan Mahalingam; Ray, Manabendra


    We are reporting structural characterization of two new hexanuclear cages (H3O)2[Cu3(μ3-OH)(μ3-NH3)(0.5)(L)3]2·8H2O (1) and (H3O)2[Cu3(μ3-OH)(μ3-H2O)(0.5)(L)3]2·8H2O (1a) where L(2-) is the dianionic form of the Schiff base of L-alanine and salicylaldehyde. The complex 1 has two C3 symmetric hydroxo bridged trinuclear halves joined by an ammonia or water molecule at the center through H-bonding. Each of the trinuclear halves is enantiopure but of opposite chirality to the other half, making the hexanuclear unit a meso isomer. Temperature dependent magnetic measurements showed the presence of ferromagnetic interactions among trinuclear Cu(II) units, a rare occurrence among trinuclear Cu(II) complexes. Characterization of the LiHL showed it to be enantiopure. Addition of a base, monitored using optical rotation, showed that racemization occurs as a result of base addition. The racemization depends on the base as well as the temperature. Base or Cu(II) induced racemization of amino acid derivatives has been indicated in a number of cases in the past but structural characterization of the products or formation of this type of chiral hexanuclear architecture was never reported. Structures of the complex and the ligand have a number of interesting H-bonding situations.

  3. Single crystal X-ray structure of the artists' pigment zinc yellow (United States)

    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.

  4. Effect of temperature and hydroxy-Al interlayers on Cs selectivity and fixation in river suspensions and soils. Final report

    International Nuclear Information System (INIS)

    Zelazny, L.W.; Martens, D.C.; El-Prince, A.M.; Rich, C.I.


    The adsorption of 137/sub Cs/ by sediments from the Savannah River Plant follows a theoretically expected linear relationship between ln Kd and l/T where kd and T are the equilibrium distribution coefficient and the temperature in kelvins, respectively. The slope of these plots decreases after removal of hydroxy Al interlayers. Hydroxy Al interlayers thus make Cs + adsorption more temperature dependent. The phenomenon is explained by considering hydroxy Al interlayers as a source of hydronium ions H 3 O + , which compete with Cs for exchange positions in wedge zones. An increase in temperature favors an increase in H 3 O ions, which in turn favors less adsorption of Cs + . Aside from their thermal effect the positively charged hydroxy aluminum polymeric groups drastically decrease the cation exchange capacity and, consequently, the adsorption of cesium. The adsorption of trace radioactive cesium by sediments from the Savannah River Plant area also follows a theoretically expected linear relationship between ln Kd and the pH of the equilibrium solution. Theoretically, the slope of these plots is proportional to the fraction of surface area occupied by pH dependent charges. Experimentally, the slope becomes zero after removal of hydroxy Al interlayers. Hydroxy Al interlayers are thus the main source for the pH dependent charges, making Cs + adsorption pH dependent also

  5. Synthetic Strategies for the Synthesis of Ternary Uranium(IV) and Thorium(IV) Fluorides. (United States)

    Klepov, Vladislav V; Felder, Justin B; Zur Loye, Hans-Conrad


    A series of new U(IV) and Th(IV) fluorides, Na 7 U 6 F 31 (1), NaUF 5 (2), NaU 2 F 9 (3), KTh 2 F 9 (4), NaTh 2 F 9 (5), (H 3 O)Th 3 F 13 (6), and (H 3 O)U 3 F 13 (7), was obtained using hydrothermal and low-temperature flux methods. Mild hydrothermal reactions with uranyl acetate as a precursor yielded 1, 7, and the monoclinic polymorph of NaU 2 F 9 , whereas direct reactions between UF 4 and NaF led to the formation of 2 and orthorhombic NaU 2 F 9 (3). This highlights an unexpected difference in reaction products when different starting uranium sources are used. All seven compounds were characterized by single-crystal X-ray diffraction, and their structures are compared on the basis of cation topology, revealing a close topological resemblance between fluorides on the basis of the layers observed in NaUF 5 (H 2 O). Phase-pure samples of 1, 2, and both polymorphs of NaU 2 F 9 were obtained, and their spectroscopic and magnetic properties were measured. The UV-vis data are dominated by the presence of U 4+ cations and agree well with the electronic transitions. Effective magnetic moments of the studied compounds were found to range from 3.08 to 3.59 μ B .

  6. Ir Spectroscopic Studies on Microsolvation of HCl by Water (United States)

    Mani, Devendra; Schwan, Raffael; Fischer, Theo; Dey, Arghya; Kaufmann, Matin; Redlich, Britta; van der Meer, Lex; Schwaab, Gerhard; Havenith, Martina


    Acid dissociation reactions are at the heart of chemistry. These reactions are well understood at the macroscopic level. However, a microscopic level understanding is still in the early stages of development. Questions such as 'how many H_2O molecules are needed to dissociate one HCl molecule?' have been posed and explored both theoretically and experimentally.1-5 Most of the theoretical calculations predict that four H_2O molecules are sufficient to dissociate one HCl molecule, resulting in the formation of a solvent separated H_3O+(H_2O)3Cl- cluster.1-3 IR spectroscopy in helium nanodroplets has earlier been used to study this dissociation process.3-5 However, these studies were carried out in the region of O-H and H-Cl stretch, which is dominated by the spectral features of undissociated (HCl)m-(H_2O)n clusters. This contributed to the ambiguity in assigning the spectral features arising from the dissociated cluster.4,5 Recent predictions from Bowman's group, suggest the presence of a broad spectral feature (1300-1360 wn) for the H_3O+(H_2O)3Cl- cluster, corresponding to the umbrella motion of H_3O+ moiety.6 This region is expected to be free from the spectral features due to the undissociated clusters. In conjunction with the FELIX laboratory, we have performed experiments on the (HCl)m(H_2O)n (m=1-2, n≥4) clusters, aggregated in helium nanodroplets, in the 900-1700 wn region. Mass selective measurements on these clusters revealed the presence of a weak-broad feature which spans between 1000-1450 wn and depends on both HCl as well as H_2O concentration. Measurements are in progress for the different deuterated species. The details will be presented in the talk. References: 1) C.T. Lee et al., J. Chem. Phys., 104, 7081 (1996). 2) H. Forbert et al., J. Am. Chem. Soc., 133, 4062 (2011). 3) A. Gutberlet et al., Science, 324, 1545 (2009). 4) S. D. Flynn et al., J. Phys. Chem. Lett., 1, 2233 (2010). 5) M. Letzner et al., J. Chem. Phys., 139, 154304 (2013). 6) J. M

  7. Stopped-flow studies of carbon dioxide hydration and bicarbonate dehydration in H2O and D2O. Acid-base and metal ion catalysis

    International Nuclear Information System (INIS)

    Pocker, Y.; Bjorkquist, D.W.


    The approach to equilibrium between carbon dioxide and bicarbonate has been followed by zero-order kinetics both from direction of CO 2 hydration and HCO 3 - dehydration. The rates are monitored at 25.0 0 C using stopped-flow indicator technique in H 2 O as well as D 2 O. The hydration of CO 2 is subject to catalysis by H 2 O (k 0 = 2.9 x 10 -2 s -1 ) and OH - (k/sub OH - / = 6.0 x 10 3 M -1 s -1 ). The value of 0.63 for the ratio k/sub OH - //k/sub OD - / is consistent with a mechanism utilizing a direct nucleophilic attack of OH - on CO 2 . In reverse direction HCO 3 - dehydration is catalyzed predominantly by H 3 O + (k/sub H 3 O + / 4.1 x 10 4 M -1 s -1 ) and to a much lesser degree by H 2 O (k 0 = 2 x 10 -4 s -1 ). The value of 0.56 for ratio k/sub H 3 O + //kD 3 O + / indicates that HCO 3 - may be protonated either in a preequilibrium step or in a rate-determining dehydration step. Both the hydration of CO 2 and the dehydration of bicarbonate are subject to general catalysis. For CO 2 , dibasic phosphate, a zinc imidazole complex, and a copper imidazole complex all enhanced the rate of hydration with respective rate coefficients of 3 x 10 -1 , 6.0, and 2.5 M -1 s -1 . For bicarbonate, monobasic phosphate catalyzed the rate of dehydration (k/sub H 2 PO 4 - / = 1 x 10 -1 M -1 s -1 ). Additionally in going from an ionic strength of 0.1 to 1.0 there was a negligible salt effect for the water-catalyzed hydration of CO 2 . However, the rate constant for the hydronium ion catalyzed dehydration of HCO 3 - was reduced from 4.1 x 10 4 M -1 s -1 to 2.3 x 10 4 M -1 s -1 for the same change in ionic strength. Finally the rate of CO 2 uptake by the complex Co(NH 3 ) 5 OH 2 3+ was followed spectrophotometrically both in H 2 O and D 2 O to determine the solvent isotope effect for a reaction known to involve a nucleophilic attack of a Co(III)-hydroxo complex on CO 2


    International Nuclear Information System (INIS)

    Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero


    Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH . radical and H 3 O + surface defects. The coupling of incoming CO molecules with the surface OH . radicals on the ice clusters yields the formation of the COOH . radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol –1 and –22 kcal mol –1 , respectively. The COOH . radicals couple with incoming NH=CH 2 molecules (experimentally detected in the ISM) to form the NHCH 2 COOH . radical glycine through energy barriers of 12 kcal mol –1 , exceedingly high at ISM cryogenic temperatures. Nonetheless, when H 3 O + is present, one proton may be barrierless transferred to NH=CH 2 to give NH 2 =CH 2 + . This latter may react with the COOH . radical to give the NH 2 CH 2 COOH +. glycine radical cation which can then be transformed into the NH 2 CHC(OH) 2 +. species (the most stable form of glycine in its radical cation state) or into the NH 2 CHCOOH . neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H 3 O

  9. Computational Study of Interstellar Glycine Formation Occurring at Radical Surfaces of Water-ice Dust Particles (United States)

    Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero


    Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH• radical and H3O+ surface defects. The coupling of incoming CO molecules with the surface OH• radicals on the ice clusters yields the formation of the COOH• radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol-1 and -22 kcal mol-1, respectively. The COOH• radicals couple with incoming NH=CH2 molecules (experimentally detected in the ISM) to form the NHCH2COOH• radical glycine through energy barriers of 12 kcal mol-1, exceedingly high at ISM cryogenic temperatures. Nonetheless, when H3O+ is present, one proton may be barrierless transferred to NH=CH2 to give NH2=CH2 +. This latter may react with the COOH• radical to give the NH2CH2COOH+• glycine radical cation which can then be transformed into the NH2CHC(OH)2 +• species (the most stable form of glycine in its radical cation state) or into the NH2CHCOOH• neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H3O+ ions to facilitate chemical

  10. Electron-induced chemistry in microhydrated sulfuric acid clusters

    Directory of Open Access Journals (Sweden)

    J. Lengyel


    Full Text Available We investigate the mixed sulfuric acid–water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT calculations. The microhydration of (H2SO4m(H2On clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4m(H2OnHSO4− and (H2OnH2SO4−. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4−  ⋅  ⋅  ⋅  H3O+ formation in the neutral H2SO4(H2On clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO42(H2On this process starts as early as n ≥ 2 water molecules. The (H2SO4m(H2OnHSO4− clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4−  ⋅  ⋅  ⋅  H3O+ ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2OnH2SO4− cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid–water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid–water aerosols are discussed.

  11. I. Cis-dichlorodiammineplatinum(II). Aquation equilibria and isotopic exchange of chloride ligands with free chloride and tetrachloroplatinate(II). II. The Szilard--Chalmers effect in solid-state systems containing the octa-μ3-chloro-octahedro-hexamolybdenum(II) cluster

    International Nuclear Information System (INIS)

    Lee, K.W.


    A titration technique was utilized to determine the equilibrium quotients for the first and second aquation steps of cis-Pt(NH 3 ) 2 Cl 2 . At 25.0 0 C and an ionic strength of 0.318 M the first and second aquation equilibrium constants are: K 1 = 3.63 +- 0.22 x 10 -3 M, ΔH 1 0 = 3.4 kcal and K 2 = 1.11 +- 0.14 x 10 -4 M, ΔH 2 0 = 10 kcal. In the ternary system, cis-Pt(NH 3 ) 2 Cl 2 :PtCl 4 2- :Cl - , the kinetics of isotopic exchange of chlorine was investigated. In addition to the expected route of exchange via aquation, a direct exchange of chlorine ligands between cis-Pt(NH 3 ) 2 Cl 2 and PtCl 4 2- occurred which is described by the rate expression. Separation procedures were devised for partial resolution of component yields resulting from dissolving a neutron-irradiated sample of (H 3 O) 2 [(Mo 6 Cl 8 )Cl 6 ] . 6H 2 O in 1.5 N HCl. A recrystallization procedure was formulated to determine the retention of activity in the parent compound of molybdenum(II) chloride clusters after neutron irradiation. The retention found in an aqueous 1.5 N HCl solution containing 1 percent (H 3 O) 2 [(Mo 6 Cl 8 )Cl 6 ] . 6H 2 O is 0.64 percent. For a solid sample of (H 3 O) 2 [(Mo 6 Cl 8 )Cl 6 ] . 6H 2 O aged 24 hours in Dry Ice after neutron irradiation, a retention of 7.0 percent was observed. Under the same conditions, a sample of (Mo 6 Cl 8 )Cl 4 with 0.8 percent and 2.7 percent water had retentions of 25.0 percent and 11.1 percent, respectively. Effects of thermal annealing and gamma ray treatment on solid samples of [(Mo 6 Cl 8 )Cl 4 ] . 2H 2 O were investigated

  12. Electron-induced chemistry in microhydrated sulfuric acid clusters (United States)

    Lengyel, Jozef; Pysanenko, Andriy; Fárník, Michal


    We investigate the mixed sulfuric acid-water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT) calculations. The microhydration of (H2SO4)m(H2O)n clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4)m(H2O)nHSO4- and (H2O)nH2SO4-. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4- ṡ ṡ ṡ H3O+) formation in the neutral H2SO4(H2O)n clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO4)2(H2O)n this process starts as early as n ≥ 2 water molecules. The (H2SO4)m(H2O)nHSO4- clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4- ṡ ṡ ṡ H3O+) ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2O)nH2SO4- cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid-water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid-water aerosols are discussed.

  13. Isotopically decoupled vibrational spectra and proton exchange rates for crystalline NH3 and ammonia hydrate (United States)

    Thornton, Cynthia; Khatkale, M. S.; Devlin, J. Paul


    Codeposits of NH3 with ND3 or D2O have been prepared at liquid nitrogen temperatures in the absence of proton exchange. Vibrational data for the anhydrous cubic crystalline ammonia, containing isolated NH3 or ND3, confirm that, relative to water ice, intermolecular coupling in ammonia ice exerts a relatively minor influence on the infrared and Raman spectra. Nevertheless, sizeable decoupling shifts, particularly for ν1, have been observed and attributed to a combination of factors including correlation field and Fermi resonance effects. The Raman polarization data has also affirmed long standing assignments of ν1 and ν3 for ammonia ice. Warming of the ammonia thin films resulted in limited isotopic scrambling at 130 K, apparently possible only through the agency of trace concentrations of water. The vibrational coupling pattern for the resultant NHD2 and NH2D molecules suggest that proton (deuteron) migration away from the exchange centers is impossible at temperatures up to 150 K. By contrast, isotopic scrambling was rapid and complete at 140 K for amorphous ammonia hydrate films (˜35% NH3, ˜65% D2O) which were also prepared without exchange at ˜90 K. The proton (deuteron) exchange rate is much greater for the amorphous ammonia hydrate at 140 K than for pure water ice. Such exchange requires both ion-pair defect formation and proton mobility. Since the NH3 suppresses the H3O+ concentration via formation of NH+4, a suppression the likes of which has been shown to stop proton exchange in water ice, the evidence strongly suggests that NH4+ in ammonia, like H3O+ in water, is an effective proton transfer agent, probably acting through a tunneling mechanism (i.e., H3N+-HṡṡṡNH3→H3NṡṡṡH-N+H3 etc.) to render the proton mobile in the ammonia hydrate. This mobility combined with the greater NH4+ concentration, relative to the H3O+ concentration in H2O ice Ic, results in isotopic scrambling at the reduced temperature.

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

    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

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

    DEFF Research Database (Denmark)

    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...

  16. Limits of the radiochemical and geochemical method for the test of nucleon stability

    Energy Technology Data Exchange (ETDEWEB)

    Bergamasco, L [CNR, Laboratorio di Cosmo-Geofisica, Turin, Italy; Texas A and M University, College Station, Tex.); Cini, G [CNR, Laboratorio di Cosmo-Geofisica; Torino, Universita, Turin, Italy)


    An estimate is obtained for the limiting nucleon lifetime that can be determined by the radiochemical method of Steinberg and Evans (1977), which counts the Ar-37 production from reactions due to nucleon decay in a large sample of KC2H3O2. To estimate the background rate, processes due to the atmospheric muon component are considered. It is found that the asymptotic limit on the maximum value of the nucleon lifetime is 2 x 10/sup 30/years. This value cannot be increased by going to larger depths or by using a larger sample, but is inherent in the method itself. To improve the limit one would have to resort to methods based on multiparticle decay modes.

  17. Experimental and kinetic modeling study of C2H4 oxidation at high pressure

    DEFF Research Database (Denmark)

    Lopez, Jorge Gimenez; Rasmussen, Christian Lund; Alzueta, Maria


    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......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...

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

    Directory of Open Access Journals (Sweden)

    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].

  19. μ-Acetato-κ2O:O′-[7,23-dibenzyl-15,31-dichloro-3,7,11,19,23,27-hexaazatricyclo[,17]tetratriconta-1(32,2,11,13,15,17(34,18,27,29(33,30-decaene-33,34-diolato-κ10N4,N5,N6,O1,O2:N1,N2,N3,O1,O2]dinickel(II perchlorate acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Juan Kong


    Full Text Available The title complex, [Ni2(C42H46Cl2N6O2(C2H3O2]ClO4·2CH3CN, was synthesized by condensation of 2,6-diformyl-4-chlorophenol with N,N-bis(aminopropylbenzylamine in the presence of NiII ions. The ligand is a 28-membered macrocycle with two identical pendant arms. The coordination geometries of the Ni atoms are both octahedral. The two Ni atoms are bridged by two phenolate O atoms of the macrocyclic ligand and one acetate ligand, with an Ni...Ni distance of 3.147 (4 Å.

  20. Application of ion chemistry to tropospheric VOC measurements

    International Nuclear Information System (INIS)

    Hansel, A.; Wisthaler, A.; Graus, M.; Grabmer, W.


    The main interest in tropospheric volatile organic compounds (VOCs) originating from biogenic sources such as forests and anthropogenic sources such as cities is because these reactive trace gases can have a significant impact on levels of oxidants such as ozone (O 3 ) and the hydroxyl radical (OH). The proton-transfer-reaction mass-spectrometry (PTR-MS) technique developed by Werner Lindingers Laboratory, utilizes positive ion chemistry to measure trace neutral concentrations in air. It has been applied in food research, medicine and environmental studies to gain gas phase information about VOCs at parts per trillion (pptv) levels.The real-time method relies on proton transfer reactions between H 3 O + primary ions and VOCs which have a higher proton affinity than water molecules. Organic trace gases such as hydrocarbons, carbonyls, alcohols, acetonitrile, and others can be monitored on-line.Results on tropospheric VOCs measurements in tropical regions and in cities are discussed. (nevyjel)

  1. Infrared spectroscopy of ionic clusters

    International Nuclear Information System (INIS)

    Price, J.M.


    This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm -1 region. The species studied include: the hydrated hydronium ions, H 3 O + (H 2 O) 3 -10 , ammoniated ammonium ions, NH 4 + (NH 3 ) 1 -10 and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH 4 + (NH 3 ) n (H 2 O) m (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs

  2. Influence of temperature and light intensity on Ru(II) complex based organic-inorganic device

    International Nuclear Information System (INIS)

    Asubay, Sezai; Durap, Feyyaz; Aydemir, Murat; Baysal, Akin; Ocak, Yusuf Selim; Tombak, Ahmet


    An organic-inorganic junction was fabricated by forming [Ru(Cy_2PNHCH_2-C_4H_3O)(η"6-p-cymene)Cl_2] complex thin film using spin coating technique on n-Si and evaporating Au metal on the film. It was seen that the structure had perfect rectification property. Current-voltage (I-V) measurements were carried out in dark and under various illumination conditions (between 50-100 mW/cm"2) and with the temperature range from 303 to 380 K. The structure showed unusually forward and reverse bias temperature and light sensing behaviors. It was seen that the current both in forward and reverse bias increased with the increase in light intensity and temperature.

  3. Atmospheric processes on ice nanoparticles in molecular beams

    Directory of Open Access Journals (Sweden)

    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.

  4. A two-dimensional ZnII coordination polymer constructed from benzene-1,2,3-tricarboxylic acid and N,N'-bis[(pyridin-4-yl)methylidene]hydrazine. (United States)

    Wang, Xiangfei; Yang, Fang; Tang, Meng; Yuan, Limin; Liu, Wenlong


    The hydrothermal synthesis of the novel complex poly[aqua(μ4-benzene-1,2,3-tricarboxylato)[μ2-4,4'-(hydrazine-1,2-diylidenedimethanylylidene)dipyridine](μ3-hydroxido)dizinc(II)], [Zn(C9H3O6)(OH)(C12H10N4)(H2O)]n, is described. The benzene-1,2,3-tricarboxylate ligand connects neighbouring Zn4(OH)2 secondary building units (SBUs) producing an infinite one-dimensional chain. Adjacent one-dimensional chains are connected by the N,N'-bis[(pyridin-4-yl)methylidene]hydrazine ligand, forming a two-dimensional layered structure. Adjacent layers are stacked to generate a three-dimensional supramolecular architecture via O-H...O hydrogen-bond interactions. The thermal stability of this complex is described and the complex also appears to have potential for application as a luminescent material.

  5. Multiscale structural characterizations of mixed U(iv)-An(iii) oxalates (An(iii) = Pu or Am) combining XAS and XRD measurements. (United States)

    Arab-Chapelet, B; Martin, P M; Costenoble, S; Delahaye, T; Scheinost, A C; Grandjean, S; Abraham, F


    Mixed actinide(III,IV) oxalates of the general formula M2.2UAn(C2O4)5·nH2O (An = Pu or Am and M = H3O(+) and N2H5(+)) have been quantitatively precipitated by oxalic precipitation in nitric acid medium (yield >99%). Thorough multiscale structural characterization using XRD and XAS measurements confirmed the existence of mixed actinide oxalate solid solutions. The XANES analysis confirmed that the oxidation states of the metallic cations, tetravalent for uranium and trivalent for plutonium and americium, are maintained during the precipitation step. EXAFS measurements show that the local environments around U(+IV), Pu(+III) and Am(+III) are comparable, and the actinides are surrounded by ten oxygen atoms from five bidentate oxalate anions. The mean metal-oxygen distances obtained by XAS measurements are in agreement with those calculated from XRD lattice parameters.

  6. Multicavity SCRF calculation of ion hydration energies

    International Nuclear Information System (INIS)

    Diercksen, B.H.F.; Karelson, M.; Tamm, T.


    The hydration energies of the proton, hydroxyl ion, and several inorganic ions were calculated using the multicavity self-consistent reaction field (MCa SCRF) method developed for the quantum-mechanical modeling of rotationally or flexible systems in dielectric media. The ionic complexes H 3 O + (H2O) 4 , OH - (H2O) 4 , NH + 4 (H2O) 4 , and Hal - (H2O) 4 , where Hal = F, Cl, or Br, have been studied. Each complex was divided between five spheres, corresponding to the central ion and four water molecules in their first coordination sphere, respectively. Each cavity was surrounded by a polarizable medium with the dielectric permittivity of water at room temperature (80). The ionic hydration energies of ions were divided into specific and nonspecific parts. After accounting for the cavity-formation energy using scaled particle theory, good agreement between the total calculated and experimental hydration energies was obtained for all ions studied

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

    DEFF Research Database (Denmark)

    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......5-, 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 is the charge state), capable of attaching H2O...

  8. Calculated Cross Sections for the Electron Impact Ionization of Molecular Ions (United States)

    Deutsch, H.; Becker, K.; Defrance, P.; Onthong, U.; Parajuli, R.; Probst, M.; Matt-Leubner, S.; Maerk, T.


    We report the results of the application of the semi- classical Deutsch-Märk (DM) formalism to the calculation of the absolute electron-impact ionization cross section of the molecular ions H2+, N2+, O2+, CD+, CO+, CO2+, H3O+, and CH4+ for which experimental data have been reported . Where available, we also compare our calculated cross sections with calculated cross sections using the BEB method of Kim and co-workers. The level of agreement between the experimentally determined and calculated cross section is satisfactory in some cases. In all cases, the calculated cross sections exceed the measured cross sections which is not surprising in view of the experimental complications in measuring ionization cross sections of molecular ions due to the presence of competing channels such as ionization dissociative ionization, and dissociative excitation. Work supported in part by FWF, OEAW, and NASA.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Effect of cation nature of Cl2- yields in pulse radiolysis of alkali metal chloride aqueous solutions

    International Nuclear Information System (INIS)

    Kabakchi, S.A.; Zansokhova, A.A.; Pikaev, A.K.


    A study is made of the amount of Cl 2 - formed during a pulsating radiolysis of potassium, rubidium and cesium chlorides in aqueous solutions saturated with air. An equation is presented relating the yield of Cl 2 - and the concentration of the starting materials. Various mechanisms describing the radiolysis of neutral aqueous solutions of the chlorides are proposed. The observed effect of the cation on the efficiency of Cl 2 - formations favours the mechanism according to which Cl 2 - forms through the reaction of Cl - ion with a ''hole''. Due to charge migration in the conductivity zone the electron transfer reaction either goes steadily by jumps. As a result of the interaction between the ''hole'' and water [H 3 O + ...OH] a complex is formed from a hydrogen ion and OH radical, which are united trhough the hydrogen bond. Disturbance of the hydrogen bond structure should increase the probability of disintegration of the complex

  11. Ion exchange in ZSM-5 zeolite

    International Nuclear Information System (INIS)

    Matthews, D.P.; Rees, L.V.C.


    The ion exchange properties of Na-ZSM5 have been studied using a number of univalent and divalent cations at 25degC and 65degC. All the univalent cations studied achieved 100 per cent exchange. The thermodynamic affinity sequence Cs > Rb=NH 4 =H 3 O>K>Na>Li was found at both temperatures for a sample with Si/Al=39. Standard enthalpies of exchange ΔH o were calculated using the van't' Hoff isochore and standard entropies of exchange were then calculated from ΔH o and ΔG o . Multivalent cations were unable to achieve 100 per cent exchange. The maximum exchange was found to increase through the series Ca 2+ cations ( 57 Fe enriched) on dehydration and rehydration following sorption and desorption of ethanol. At least 3 sites for Fe 2+ were observed in the dehydrated zeolite. (author)

  12. Electron-Stimulated Desorption of Positive Ions from Methanol Adsorbed on a Solid Ar Substrate (United States)

    Kawanowa, H.; Hanatani, K.; Gotoh, Y.; Souda, R.

    Electron-stimulated desorption (ESD) of positive ions from weakly physisorbed molecules has been investigated. From methanol adsorbed on a solid Ar substrate, the protonated cluster ions of the type H+(CH3OH)n (n = 1 - 4) are emitted, together with the fragment ions such as CHn+ (n = 0 - 3), H3O+, CHO+, CH3O+, etc. The yields of these ions are markedly enhanced at the smallest coverage and decay steeply with increasing coverage. Coulomb explosion between valence holes confined in adsorbed nanoclusters is responsible for the enhanced ion yields. Very few ions except for H+ are emitted from a thick layer as well as nanoclusters adsorbed directly on a metal substrate due to the delocalization of valence holes.

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Crystal structure of levomepromazine maleate

    Directory of Open Access Journals (Sweden)

    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.

  15. Valorización de un residuo proveniente de la industria de galvanizado en caliente mediante la síntesis hidrometalúrgica de sales de zinc

    Directory of Open Access Journals (Sweden)

    Julio Andrés Casal-Ramos


    Full Text Available The possibility of adding value to a residual dust from hot-dip galvanizing process was explored, through the synthesis of potentially marketable organic zinc salts. The valorization process started by dissolving the residue in HCl, citric acid was then added and zinc salts were finally precipitated by the addition of NaOH. In another experiment, absolute ethanol was added as a modifying agent. In both cases, the products were fine white powders which were characterized by pycnometry, atomic spectroscopy, scanning electron microscopy, x–ray diffraction and infrared spectroscopy. In the synthesized products, the following phases were identified: Zn(C2H3O22.2H2O, Na3C6H5O7.2H2O and NaCl

  16. Equilibrium states of the systems B-Cl-H and B-Cl-H-O at elevated temperatures

    International Nuclear Information System (INIS)

    Wagner, W.; Bochmann, G.


    By means of the computer program EHMSYS the equilibrium compositions are calculated in the reaction systems H 2 /BCl 3 and H 2 /BCl 3 /H 2 O with initial mixtures of 50, 25, 10, 5, 2, and 1 volume percent BCl 3 as well as initial volume portions of 0, 0.02, 0.05, 0.10, 0.25, and 0.50 volume percent gaseous water at temperatures of 800, 1000, 1200, and 1400 K. The results confirm the great complexity of the reaction system. The presence of oxygen causes the formation of gaseous B 3 H 3 O 3 and B 3 Cl 3 O 3 and in general a total suppression or at least a drastic decrease of the deposition of solid boron. Coincidentally, the amounts of gaseous haloboranes at the eqiulibrium are increased

  17. Poly[[(μ4-benzene-1,3,5-tricarboxylato-κ4O1:O1′:O2:O3bis(2,2-bipyridine-κ2N,N′(μ2-hydroxidodicopper(II] trihydrate

    Directory of Open Access Journals (Sweden)

    Mohamed N. El-kaheli


    Full Text Available In the title two-dimensional coordination polymer, {[Cu2(C9H3O6(OH(C10H8N22]·3H2O}n, each of the two independent CuII atoms is coordinated by a bridging OH group, two O atoms from two benzene-1,3,5-tricarboxylate (L ligands and two N atoms from a 2,2- bipyridine (bipy ligand in a distorted square-pyramidal geometry. Each L ligand coordinates four CuII atoms, thus forming a polymeric layer parallel to the bc plane with bipy molecules protruding up and down. The lattice water molecules involved in O—H...· O hydrogen bonding are situated in the inner part of each layer. The crystal packing is consolidated by π–π interactions between the aromatic rings of bipy ligands from neigbouring layers [intercentroid distance = 3.762 (3 Å].

  18. On rhenium (7) state in aqueous solutions

    International Nuclear Information System (INIS)

    Sinyakova, G.S.


    The methods of spectrophotometry, electric conductivity and potentiometric titration have been used in studying the interaction in the system Re(7)-H 3 O + -H 2 O. It has been found that sodium perrhenate and perrhenic acid dissociate on dilution but not the way typical of binary electrolytes. Perrhenic acid is a mixture of the acids HReO 4 and H 5 ReO 6 . The two acids do not undergo differential titration. The conventional ionization constant, as calculated from the data of potentiometric titration, K 1 =(2.34+-0.52)x10 -2 . A step-wise dissociation of the H 4 ReO 6 - anion has been found, K 2 =(2.04+-0.30)x10 -8 , K 3 =(4.90+-0.20)x10 -12

  19. Nuclear magnetic resonance studies of ion motion in solid electrolytes. Annual report, June 1, 1982-March 31, 1983

    International Nuclear Information System (INIS)

    Bjorkstam, J.L.


    An extensive investigation of a number of Li-Na beta-alumina crystals was carried out. It was found that the reaction of beta-aluminas with water involves partial substitution of M + by H 3 O + (or H + ) and carbonation at the crystal surface; i.e., reaction of a hydroxide with CO 2 . NMR spin-lattice relaxation data have been collected over the 4.2-100 0 K temperature interval at several frequencies for a number of beta-aluminas. Extensive efforts on the NMR investigation of lithium, proton, and deuteron nuclei in both normal and deuterated single crystals of lithium-iodide-monohydrate are reported. An extensive investigation of the thermodynamics and cation exchange properties of the AgI: Ag 2 O-B 2 O 3 glasses has been performed. Cation exchange techniques to produce new vitreous electrolytes were not successful

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

    DEFF Research Database (Denmark)

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


    to be readily determined. Analysis of the 2 H quadrupole interaction indicates that the FeOD2 groups are mobile, undergoing rapid 180 degrees flips on the NMR time scale; the D2O/D3O+ species (located on the A sites) undergo close to isotropic motion, whereas the Fe20D groups are rigid and are hydrogen......-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. Poly(2-FurylMethylenesulfide as a Resin to Uptake of Metal Ions from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    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.

  2. High resolution studies of the origins of polyatomic ions in inductively coupled plasma-mass spectrometry, Part I. Identification methods and effects of neutral gas density assumptions, extraction voltage, and cone material

    International Nuclear Information System (INIS)

    Ferguson, Jill Wisnewski; Houk, R.S.


    Common polyatomic ions (ArO + , NO + , H 2 O + , H 3 O + , Ar 2 + , ArN + , OH + , ArH + , O 2 + ) in inductively coupled plasma-mass spectrometry (ICP-MS) are identified using high mass resolution and studied using kinetic gas temperatures (T gas ) determined from a dissociation reaction approach. Methods for making accurate mass measurements, confirming ion identifications, and correcting for mass bias are discussed. The effects of sampler and skimmer cone composition and extraction voltage on polyatomic ion formation are also explored. Neutral species densities at several locations in the extraction interface are estimated and the corresponding effects of the T gas value are calculated. The results provide information about the origins of background ions and indicate possible locations for their formation or removal

  3. 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

    Directory of Open Access Journals (Sweden)

    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.

  4. Enhanced Oxidation of Isoprene and Monoterpenes in High and Low NOx Conditions (United States)

    Tokarek, T. W.; Gilman, J.; Lerner, B. M.; Koss, A.; Yuan, B.; Taha, Y. M.; Osthoff, H. D.; Warneke, C.; De Gouw, J. A.


    In the troposphere, the photochemical oxidation of volatile organic compounds (VOCs) is primarily initiated by their reactions with the hydroxyl radical (OH) which yields peroxy radicals (HO2 and RO2). Concentrations of OH and the rates of VOC oxidation depend on the efficiency of peroxy radical recycling to OH. Radical recycling mainly occurs through reaction of HO2 with NO to produce NO2 and, ultimately, ozone (O3). Hence, the rate of VOC oxidation is dependent on NOx (=NO+NO2) concentration. The Shale Oil and Natural Gas Nexus (SONGNEX) campaign was conducted from March 17 to April 29, 2015 with the main goal of identifying and quantifying industrial sources of pollutants throughout the United States, in particular those associated with the production of oil and natural gas. In this work, a case study of biogenic VOC oxidation within and outside a power plant plume in the Haynesville basin near the border of Texas and Louisiana is presented. Isoprene, monoterpenes and their oxides were measured by H3O+ chemical ionization mass spectrometry (H3O+ CIMS) in high time resolution (1 s). Further, an improved Whole Air Sampler (iWAS) was used to collect samples for post-flight analysis by gas chromatography mass spectrometric detection (GC-MS) and yielded speciated quantification of biogenic VOCs. The monoterpene oxide to monoterpene ratio follows the spatial extent of the plume as judged by another tracer (NOx), tracking the enhancement of oxidation rates by NOx. The observations are rationalized with the aid of box modeling using the Master Chemical Mechanism (MCM).

  5. Simulations of electrolytes at the liquid-liquid interface and of lanthanide cations complexes in gas phase

    International Nuclear Information System (INIS)

    Berny, F.


    Two processes related to liquid/liquid extraction of ions by extractant molecules were studied: the ion approach at the interface and the ion complexation by ligands. In the first part, the behaviour of salts at the chloroform/water interface was simulated by molecular dynamics. The aim was to understand the way these salts ions approach the interface in order to be extracted. Some ions are repelled by the interface (K + , Cl - , UO 2 2+ , Na + , NO 3 - ) whereas others adsorb (amphiphilic molecules and also ClO 4 - , SCN - , guanidinium Gu + and picrate Pic - ). The surface-active counter-ions make the ion approach at the interface easier. In a perfectly homogeneous mixture of the two solvents (water and chloroform) de-mixing, the ions seem to influence the phases separation rate. Nitric acid which is known to favour liquid/liquid extraction reveals strong adsorption at the interface in its neutral form and a smaller one in its ionic form (H 3 O + /NO 3 - ). HNO 3 and H 3 O + display particular orientations at the interface: hydrogen atoms are pointing in the direction of the water slab. The nature of the organic phase can also influence the ion approach at the interface. For example, Gu + and Pic - adsorb much less at the supercritical CO 2 /water interface than at the chloroform/water interface. In the second part, complexes of La 3+ , Eu 3+ and Yb 3+ with ligands such as amide, urea, thio-amide, thiourea were studied by quantum mechanics. Our calculations show that cation-ligand interactions depend on the nature of substituents on ligands, on the presence of counter-ions or on the number of ligands in the complex. Sulfur compounds seem to less interact with cations than oxygen compounds. Ureas interact as much as amides and are potentially good ligands. (author)

  6. Effects of zero point vibration on the reaction dynamics of water dimer cations following ionization. (United States)

    Tachikawa, Hiroto


    Reactions of water dimer cation (H2O)2+ following ionization have been investigated by means of a direct ab initio molecular dynamics method. In particular, the effects of zero point vibration and zero point energy (ZPE) on the reaction mechanism were considered in this work. Trajectories were run on two electronic potential energy surfaces (PESs) of (H2O)2+: ground state ( 2 A″-like state) and the first excited state ( 2 A'-like state). All trajectories on the ground-state PES lead to the proton-transferred product: H 2 O + (Wd)-H 2 O(Wa) → OH(Wd)-H 3 O + (Wa), where Wd and Wa refer to the proton donor and acceptor water molecules, respectively. Time of proton transfer (PT) varied widely from 15 to 40 fs (average time of PT = 30.9 fs). The trajectories on the excited-state PES gave two products: an intermediate complex with a face-to-face structure (H 2 O-OH 2 ) + and a PT product. However, the proton was transferred to the opposite direction, and the reverse PT was found on the excited-state PES: H 2 O(Wd)-H 2 O + (Wa) → H 3 O + (Wd)-OH(Wa). This difference occurred because the ionizing water molecule in the dimer switched between the ground and excited states. The reaction mechanism of (H2O)2+ and the effects of ZPE are discussed on the basis of the results. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  7. Theory favors a stepwise mechanism of porphyrin degradation by a ferric hydroperoxide model of the active species of heme oxygenase. (United States)

    Kumar, Devesh; de Visser, Samuël P; Shaik, Sason


    The report uses density functional theory to address the mechanism of heme degradation by the enzyme heme oxygenase (HO) using a model ferric hydroperoxide complex. HO is known to trap heme molecules and degrade them to maintain iron homeostasis in the biosystem. The degradation is initiated by complexation of the heme, then formation of the iron-hydroperoxo species, which subsequently oxidizes the meso position of the porphyrin by hydroxylation, thereby enabling eventually the cleavage of the porphyrin ring. Kinetic isotope effect studies indicate that the mechanism is assisted by general acid catalysis, via a chain of water molecules, and that all the events occur in concert. However, previous theoretical treatments indicated that the concerted mechanism has a high barrier, much higher than an alternative mechanism that is initiated by O-O bond homolysis of iron-hydroperoxide. The present contribution studies the stepwise and concerted acid-catalyzed mechanisms using H(3)O(+)(H(2)O)(n)(), n = 0-2. The effect of the acid strength is tested using the H(4)N(+)(H(2)O)(2) cluster and a fully protonated ferric hydroperoxide. All the calculations show that a stepwise mechanism that involves proton relay and O-O homolysis, in the rate-determining step, has a much lower barrier (>10 kcal/mol) than the corresponding fully concerted mechanism. The best fit of the calculated solvent kinetic isotope effect, to the experimental data, is obtained for the H(3)O(+)(H(2)O)(2) cluster. The calculated alpha-deuterium secondary kinetic isotope effect is inverse (0.95-0.98), but much less so than the experimental value (0.7). Possible reasons for this quantitative difference are discussed. Some probes are suggested that may enable experiment to distinguish the stepwise from the concerted mechanism.

  8. Furfural: The Unimolecular Dissociative Photoionization Mechanism of the Simplest Furanic Aldehyde. (United States)

    Winfough, Matthew; Voronova, Krisztina; Muller, Giel; Laguisma, Gabrielle; Sztáray, Bálint; Bodi, Andras; Meloni, Giovanni


    The unimolecular dissociation reactions of energy-selected furfural cations have been studied by imaging photoelectron photoion coincidence spectroscopy at the vacuum-ultraviolet (VUV) beamline of the Swiss Light Source. In the photon energy range of 10.9-14.5 eV, furfural ions decay by numerous fragmentation channels. Modeling the breakdown diagram yielded the 0 K appearance energies of 10.95 ± 0.10, 11.16, and 12.03 eV for the c-C 4 H 3 O-CO + (m/z = 95), c-C 4 H 4 O + (m/z = 68), and c-C 3 H 3 + (m/z = 39) fragment ions, respectively, formed by parallel dissociation channels. An internal conversion from the A″ to the A' electronic state via a conical intersection takes place along the reaction coordinate in the case of the H-loss channel (c-C 4 H 3 O-CO + formation). Quantum chemical calculations and experimental results confirmed a fast conversion to the A' state and that the rate-determining step is a tight transition state on the potential energy surface. Appearance energies were also derived for the sequential dissociation products from the furan cation, c-C 4 H 4 O + , for the formation of CH 2 CO + (m/z = 42), C 3 H 4 + (m/z = 40), and CHO + (m/z = 29) at 12.81, 12.80, and 13.34 eV, respectively. Statistical rate theory modeling of the breakdown diagram can also be used to predict the fractional ion abundances and thermal shifts in mass spectrometric pyrolysis studies to help assigning the m/z channels either to ionization of the neutrals or to dissociative ionization processes, with potential use for combustion diagnostics. The cationic geometry optimizations yielded functional-dependent spurious DFT minima and a deviating planar MP2 optimized geometry, which are briefly discussed.

  9. 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. (United States)

    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].

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

    Directory of Open Access Journals (Sweden)

    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. Solubility and dissolution kinetics study of uranium phosphates and vanadates: implications for the front end of the electronuclear cycle

    International Nuclear Information System (INIS)

    Cretaz, F.


    In the current context of restart of the nuclear energy, the needs in uranium are expected to increase significantly. Moreover, in a perspective of sustainable development, the exploitation, the treatment and the purification of uranium ores need to be optimized. It is thus necessary to determine reliable thermodynamic data (and especially solubility constants) for the systems of interest, especially uranium(VI) phosphates and vanadates. In this aim, a multi parametric study of the dissolution of meta-torbernite Cu 0.8 (H 3 O) 0.2 (UO 2 ) 2 (PO 4 ) 2.8 H 2 O, meta-autunite Ca(UO 2 ) 2 (PO 4 ) 2.6 H 2 O, meta-ankoleite K 2 (UO 2 ) 2 (PO 4 ) 2.6 H 2 O and carnotite K 2 (UO 2 ) 2 (VO 4 ) 2.3 H 2 O was undertaken. First, analogues of these four minerals were synthesized, based only on dry chemistry process for carnotite or on wet chemistry methods for the phosphate phases. They were then extensively characterized (in terms of structure, microstructure and chemical composition). It particularly highlighted the similar structures of such compounds. The anionic groups (PO 4 3- or V 2 O 8 6- ) and uranyl form parallel layers between which counter cations (Cu 2+ , Ca 2+ or K + ) and water molecules are inserted. However, the counter cations present in the interlayer space of the three phosphate phases present different lability. The synthetic phases were also compared to their natural analogues, except for meta-ankoleite, which allowed us to point out significant differences in the composition (presence of impurities in natural samples) and the morphology (grain size). The dissolution of these phases was then studied from a kinetic and thermodynamic point of view, through leaching tests in static and dynamic conditions, in various acid media (sulfuric, nitric and hydrochloric) and at different temperatures. In these conditions, the dissolution of meta-autunite was found to be un-congruent due to the precipitation of uranyl phosphate then avoiding the determination of

  12. Hydrothermal preparation of nickel(II)/uranium(IV) fluorides with one-, two-, and three-dimensional topologies. (United States)

    Bean, Amanda C; Sullens, Tyler A; Runde, Wolfgang; Albrecht-Schmitt, Thomas E


    A modified compositional diagram for the reactions of Ni(C(2)H(3)O(2))(2).4H(2)O with UO(2)(C(2)H(3)O(2))(2).2H(2)O and HF in aqueous media under mild hydrothermal conditions (200 degrees C) has been completed to yield three Ni(II)/U(IV) fluorides, Ni(H(2)O)(4)UF(6).1.5H(2)O (1), Ni(2)(H(2)O)(6)U(3)F(16).3H(2)O (2), and Ni(H(2)O)(2)UF(6)(H(2)O) (3). The structure of 1 consists of one-dimensional columns constructed from two parallel chains of edge-sharing dodecahedral [UF(8)] units. The sides of the columns are terminated by octahedral Ni(II) units that occur as cis-[Ni(H(2)O)(4)F(2)] polyhedra. In contrast, the crystal structure of 2 reveals a two-dimensional Ni(II)/U(IV) architecture built from edge-sharing tricapped trigonal prismatic [UF(9)] units. The top and bottom of the sheets are capped by fac-[Ni(H(2)O)(3)F(3)] octahedra. The structure of 3 is formed from [UF(8)(H(2)O)] tricapped trigonal prisms that edge share with one another to form one-dimensional chains. These chains are then joined together into a three-dimensional network by corner sharing with trans-[Ni(H(2)O)(2)F(4)] octahedra. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 14.3383(8) A, b = 15.6867(8) A, c = 8.0282(4) A, Z = 8; 2, hexagonal, space group P6(3)/mmc, a = 7.9863(5) A, c = 16.566(1) A, Z = 2; 3, monoclinic, space group C2/c, a = 12.059(1) A, b = 6.8895(6) A, c = 7.9351(7) A, beta = 92.833(2) degrees, Z = 4.

  13. Solubility properties of synthetic and natural meta-torbernite (United States)

    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.

  14. Theoretical characterizations of novel C2H5O+ reactions (United States)

    Hudson, Charles E.; McAdoo, David J.


    Assorted reactions of C2H5O+ isomers are characterized by theory, including tracing their courses by means of intrinsic reaction coordinate computations. We establish that CH3CH=OH+ eliminates methane by transferring H from oxygen to a methyl hydrogen and then to the CC bond to produce CHO++CH4. This adds to the limited knowledge of the involvement of hypervalent structures in the reactions of cations in the gas phase. Second, we characterized the course of CH3CH=OH+-->H3O++HC[triple bond; length as m-dash]CH. In this dissociation, H first migrates from the methyl to the oxygen to give O-protonated vinyl alcohol, a stable intermediate. Then the H2O swings outward to over the middle of the CC bond while one of the two hydrogens on the non-O-bearing carbon revolves to between the oxygen and the two carbons, leading to formation of a [H3O+ HC[triple bond; length as m-dash]CH] complex. This complex contains sufficient energy to dissociate its partners because a high barrier is crossed in its formation. Third, we found that methane elimination from CH3O+=CH2 involves stretching of the CH3---O bond and then rotation of the methyl so that a methyl hydrogen is pointed directly toward the oxygen. This reaction is completed by further rotation of the methyl to abstract a methylene hydrogen to the opposite side of the methyl from that initially bonded to oxygen. This clearly establishes that this dissociation takes place through an ion-neutral complex. Each of the reaction coordinates for the three preceding reactions traverses a novel bonding stage involving H, evidence that such are not unusual in gas phase ion chemistry. Finally, we showed that in the rearrangement CH3O+=CH2-->CH2=O+CH3, before Ht is transferred CH2 rotates around the C=C bond from being in the skeletal plane to being perpendicular to it, and Ht remains in the skeletal plane throughout its transfer. This pathway appears to balance avoiding an orbital symmetry-forbidden suprafacial transition state with

  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

    Directory of Open Access Journals (Sweden)

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

    Majzlan, J.; Navrotsky, A.; McCleskey, R. Blaine; Alpers, Charles 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.

  17. Experimental investigation of H2/D2 isotope separation by cryo-adsorption in metal-organic frameworks

    International Nuclear Information System (INIS)

    Teufel, Julia Sonja


    Light-gas isotopes differ in their adsorption behavior under cryogenic conditions in nanoporous materials due to their difference in zero-point energy. However, the applicability of these cryo-effects for the separation of isotope mixtures is still lacking an experimental proof. The current work describes the first experimentally obtained H 2 /D 2 selectivity values of nanoporous materials measured by applying isotope mixtures in low-temperature thermal desorption spectroscopy (TDS). The dissertation contains the following key points: 1) A proof of the experimental method, i.e. it is shown that TDS leads to reasonable selectivity values. 2) A series of small-pore MFU-4 derivatives (MOFs) is shown to separate isotope mixtures by quantum sieving, i.e. by the difference in the adsorption kinetics. The influence of the pore size on the selectivity is studied systematically for this series. 3) Two MOFs with pores much larger than the kinetic diameter of H 2 do not exhibit kinetic quantum sieving. However, if the MOFs are exposed to an isotope mixture, deuterium adsorbs preferentially at the adsorption sites with high heats of adsorption. According to the experimental results, these strong adsorption sites can be every selective for deuterium. On the basis of the experimentally obtained selectivity values, technical implementations for H 2 /D 2 light-gas isotope separation by cryo-adsorption are described.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Sulfurized limonite as material for fast decomposition of organic compounds by heterogeneous Fenton reaction

    International Nuclear Information System (INIS)

    Toda, Kei; Tanaka, Toshinori; Tsuda, Yutaka; Ban, Masahiro; Koveke, Edwin P.; Koinuma, Michio; Ohira, Shin-Ichi


    Graphical abstract: - Highlights: • Used limonite degrades organic compounds by heterogeneous Fenton reaction. • Sulfurized limonite removes methylene blue color in seconds. • Recycled limonite can be used for biogas purification and wastewater treatment. - Abstract: Rapid decomposition of wastewater contaminants using sulfurized limonite (S-limonite) was investigated. Limonite is used for desulfurization of biogases, and S-limonite is obtained from desulfurization plants as solid waste. In this work, the profitable use of S-limonite in water treatment was examined. The divalent Fe in S-limonite was expected to produce OH radicals, as Fe 2+ ions and limonite thermally treated with H 2 do. Methylene blue was used for batch-wise monitoring of the decomposition performance. The decomposition rate was fast and the methylene blue solution color disappeared in only 10 s when a small amount of H 2 O 2 was added (1 mM in the sample solution) in the presence of S-limonite. The OH radicals were formed by a heterogeneous reaction on the S-limonite surface and Fenton reaction with dissolved Fe 2+ . The decomposition of pentachlorophenol was also examined; it was successfully decomposed in batch-wise tests. The surfaces of limonite before sulfurization, S-limonite, and S-limonite after use for water treatment were performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that S-limonite reverted to limonite after being used for water treatment

  1. Metal extraction by alkyl substituted diphosphonic acids. Part 1. P,P'-Di(2-ethylhexyl) methanediphosphonic acid

    International Nuclear Information System (INIS)

    Chiarizia, R.; Horwitz, E.P.; Rickert, P.G.; Herlinger, A.W.


    Two novel extractants, p,p'-di(2-ethylhexyl) methanediphosphonic acid (H 2 DEH[MDP]) and p,p'-dioctyl methanediphosphonic acid (H 2 DO[MDP]) have been synthesized at high purity and yield. H 2 DEH[MDP] was selected for metal extraction studies because of its better physical properties. An investigation of the extraction of alkaline earth cations, Fe(111) and representative tri-, tetra- and hexavalent actinide ions from nitric acid solutions into o-xylene solutions of H 2 DEH[MDP] at different concentrations was performed. With a few exceptions, the acid dependencies of the extraction of the above metal species strongly resembles those measured in the uptake of the same metals by the chelating ion exchange resin Diphonix R , which contains gem-diphosphonic acid groups chemically attached to a polymeric matrix. The almost lack of acid dependency observed with Fe(III) and tetra- and hexavalent actinides indicates that these ions are chelated by H 2 DEH[MDP] mostly through the P=O groups of the extractant. With Fe(111) and the actinides, variable slopes of the extractant dependencies were measured, their values being strongly dependent on the acidity of the aqueous phase. H 2 DEH[MDP] possesses an extraordinary affinity for actinides and Fe(111). 26 refs., 7 figs

  2. Acidity enhancement of unsaturated bases of group 15 by association with borane and beryllium dihydride. Unexpected boron and beryllium Brønsted acids. (United States)

    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.

  3. Deuterium fractionation in dense interstellar clouds

    International Nuclear Information System (INIS)

    Millar, T.J.; Bennett, A.; Herbst, E.


    The time-dependent gas-phase chemistry of deuterium fractionation in dense interstellar clouds ranging in temperature between 10 and 70 K was investigated using a pseudo-time-dependent model similar to that of Brown and Rice (1986). The present approach, however, considers much more complex species, uses more deuterium fractionation reactions, and includes the use of new branching ratios for dissociative recombinations reactions. Results indicate that, in cold clouds, the major and most global source of deuterium fractionation is H2D(+) and ions derived from it, such as DCO(+) and H2DO(+). In warmer clouds, reactions of CH2D(+), C2HD(+), and associated species lead to significant fractionation even at 70 K, which is the assumed Orion temperature. The deuterium abundance ratios calculated at 10 K are consistent with those observed in TMC-1 for most species. However, a comparison between theory and observatiom for Orion, indicates that, for species in the ambient molecular cloud, the early-time results obtained with the old dissociative recombination branching ratios are superior if a temperature of 70 K is utilized. 60 refs

  4. Deuterium fractionation in dense interstellar clouds (United States)

    Millar, T. J.; Bennett, A.; Herbst, Eric


    The time-dependent gas-phase chemistry of deuterium fractionation in dense interstellar clouds ranging in temperature between 10 and 70 K was investigated using a pseudo-time-dependent model similar to that of Brown and Rice (1986). The present approach, however, considers much more complex species, uses more deuterium fractionation reactions, and includes the use of new branching ratios for dissociative recombinations reactions. Results indicate that, in cold clouds, the major and most global source of deuterium fractionation is H2D(+) and ions derived from it, such as DCO(+) and H2DO(+). In warmer clouds, reactions of CH2D(+), C2HD(+), and associated species lead to significant fractionation even at 70 K, which is the assumed Orion temperature. The deuterium abundance ratios calculated at 10 K are consistent with those observed in TMC-1 for most species. However, a comparison between theory and observatiom for Orion, indicates that, for species in the ambient molecular cloud, the early-time results obtained with the old dissociative recombination branching ratios are superior if a temperature of 70 K is utilized.

  5. Inner Source Pickup Ions Observed by Ulysses (United States)

    Gloeckler, G.


    The existence of an inner source of pickup ions close to the Sun was proposed in order to explain the unexpected discovery of C+ in the high-speed polar solar wind. Here I report on detailed analyses of the composition and the radial and latitudinal variations of inner source pickup ions measured with the Solar Wind Ion Composition Spectrometer on Ulysses from 1991 to 1998, approaching and during solar minimum. We find that the C+ intensity drops off with radial distance R as R-1.53, peaks at mid latitudes and drops to its lowest value in the ecliptic. Not only was C+ observed, but also N+, O+, Ne+, Na+, Mg+, Ar+, S+, K+, CH+, NH+, OH+, H2O+, H3O+, MgH+, HCN+, C2H4+, SO+ and many other singly-charged heavy ions and molecular ions. The measured velocity distributions of inner source pickup C+ and O+ indicate that these inner source pickup ions are most likely produced by charge exchange, photoionization and electron impact ionization of neutrals close to the Sun (within 10 to 30 solar radii). Possible causes for the unexpected latitudinal variations and the neutral source(s) producing the inner source pickup ions as well as plausible production mechanisms for inner source pickup ions will be discussed.

  6. Driving forces of individual BVOC emissions from a spruce tree in Central Germany; results from a dynamic enclosure study. (United States)

    Bourtsoukidis, S.; Dittmann, A.; Jacobi, S.; Bonn, B.


    We have conducted seasonal ambient and emission measurements of a series of biogenic VOCs such as monoterpenes (MT), sesquiterpenes (SQT), isoprene, methanol, methyl chavicol and acetaldehyde. Therefore a plant enclosure technique was applied in order to investigate a Central European spruce forest and its emissions responses to meteorological and environmental parameters. A healthy ≈15m tall Norway spruce tree was selected and a vegetation enclosure technique was applied from April to November 2011. VOCs are measured by PTR-MS, while samples have also been analyzed with GC-MS (Gas Chromatography - Mass Spectrometry) techniques for intercomparison and identification of individual VOCs. E/N ratio was adjusted at 117Td[2] and the primary ion signal (H3O+) was continuously above 4×10^7cps, implying a high sensitivity to our measurements. Temperature, relative humidity, ozone, photosynthetic active radiation (PAR) and CO2 concentrations were continuously measured inside the plant cuvette. Meteorological and environmental parameters (radiation, atmospheric pressure, wind velocity, wind direction, temperature, O3, relative humidity, soil moisture, precipitation, global radiation, H2O, NO, NO2) were measured by HLUG (Hessian Agency for Environment and Geology) and DWD (German Weather Service), 50 meters away from the measuring site. In a peculiar season, which was characterized by a warm spring (temperature anomaly >40C), a wet summer (precipitation anomaly 126-150%) and an extremely dry autumn (precipitation anomaly monoterpene emission rate variability: model evaluations and sensitivity analyses, Journal of Geophysical Research., 98, 12609-12617, 1993.

  7. Ionization Capabilities of Hydronium Ions and High Electric Fields Produced by Atmospheric Pressure Corona Discharge. (United States)

    Sato, Natsuhiko; Sekimoto, Kanako; Takayama, Mitsuo


    Atmospheric pressure corona discharge (APCD) was applied to the ionization of volatile organic compounds. The mass spectra of analytes having aromatic, phenolic, anilinic, basic and aliphatic in nature were obtained by using vapor supply and liquid smear supply methods. The vapor supply method mainly gave protonated analytes [A+H] + caused by proton transfer from hydronium ion H 3 O + , except for benzene, toluene and n -hexane that have lower proton affinity. The use of the liquid smear supply method resulted in the formation of molecular ion A ·+ and/or dehydride analyte [A-H] + , according to the nature of analytes used. The formation of A ·+ without fragment ions could be explained by the electron tunneling via high electric fields 10 8  V/m at the tip of the corona needle. The dehydride analytes [A-H] + observed in the mass spectra of n -hexane, di- and tributylamines may be explained by the hydride abstraction from the alkyl chains by the hydronium ion. The hydronium ion can play the two-roles for analytes, i.e. , the proton donor to form [A+H] + and the hydride acceptor to form [A-H] + .

  8. A simple and effective solution to the constrained QM/MM simulations (United States)

    Takahashi, Hideaki; Kambe, Hiroyuki; Morita, Akihiro


    It is a promising extension of the quantum mechanical/molecular mechanical (QM/MM) approach to incorporate the solvent molecules surrounding the QM solute into the QM region to ensure the adequate description of the electronic polarization of the solute. However, the solvent molecules in the QM region inevitably diffuse into the MM bulk during the QM/MM simulation. In this article, we developed a simple and efficient method, referred to as the "boundary constraint with correction (BCC)," to prevent the diffusion of the solvent water molecules by means of a constraint potential. The point of the BCC method is to compensate the error in a statistical property due to the bias potential by adding a correction term obtained through a set of QM/MM simulations. The BCC method is designed so that the effect of the bias potential completely vanishes when the QM solvent is identical with the MM solvent. Furthermore, the desirable conditions, that is, the continuities of energy and force and the conservations of energy and momentum, are fulfilled in principle. We applied the QM/MM-BCC method to a hydronium ion(H3O+) in aqueous solution to construct the radial distribution function (RDF) of the solvent around the solute. It was demonstrated that the correction term fairly compensated the error and led the RDF in good agreement with the result given by an ab initio molecular dynamics simulation.

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

    International Nuclear Information System (INIS)

    Norberg, Seth A; Johnsen, Eric; Tian, Wei; 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 H 3 O + aq , O 3 − aq , and O 2 − aq being the dominant terminal species. More aqueous OH aq , H 2 O 2aq , and O 3aq 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, N x O y species do not accumulate in the volume. As a result, aqueous nitrites, nitrates, and peroxynitrite, and the HNO 3aq and HOONO aq , which trace their origin to solvated N x O y , have low densities. (paper)

  10. Computational screening of functional groups for capture of toxic industrial chemicals in porous materials. (United States)

    Kim, Ki Chul; Fairen-Jimenez, David; Snurr, Randall Q


    A thermodynamic analysis using quantum chemical methods was carried out to identify optimal functional group candidates that can be included in metal-organic frameworks and activated carbons for the selective capture of toxic industrial chemicals (TICs) in humid air. We calculated the binding energies of 14 critical TICs plus water with a series of 10 functional groups attached to a naphthalene ring model. Using vibrational calculations, the free energies of adsorption were calculated in addition to the binding energies. Our results show that, in these systems, the binding energies and free energies follow similar trends. We identified copper(i) carboxylate as the optimal functional group (among those studied) for the selective binding of the majority of the TICs in humid air, and this functional group exhibits especially strong binding for sulfuric acid. Further thermodynamic analysis shows that the presence of water weakens the binding strength of sulfuric acid with the copper carboxylate group. Our calculations predict that functionalization of aromatic rings would be detrimental to selective capture of COCl 2 , CO 2 , and Cl 2 under humid conditions. Finally, we found that forming an ionic complex, H 3 O + HSO 4 - , between H 2 SO 4 and H 2 O via proton transfer is not favorable on copper carboxylate.

  11. Origins of IR Intensity in Overtones and Combination Bands in Hydrogen Bonded Systems (United States)

    Horvath, Samantha; McCoy, Anne B.


    As the infrared spectra of an increasing number of hydrogen bonded and ion/water complexes have been investigated experimentally, we find that they often contain bands with significant intensity that cannot be attributed to fundamental transitions. In this talk, we explore several sources of the intensity of these overtone and combination bands. A common source of intensity is mode-mode coupling, as is often seen between the proton transfer coordinate and the associated heavy atom vibration. A second important mechanism involves large changes in the dipole moment due the loss of a hydrogen bond. This results in intense overtone transitions involving non-totally symmetric vibrations as well as the introduction of intense combination bands involving intramolecular bending coupled to hindered rotations. These effects will be discussed in the context of several systems, including the spectra of complexes of argon atoms with {H}_3{O}^+, F^-\\cdotH_2O, Cl^-\\cdotH_2O, protonated water clusters,^a and HOONO. T. Guasco, S. Olesen and M. A. Johnson, private communication S. Horvath, A. B. McCoy, J. R. Roscioli and M. A. Johnson, J. Phys. Chem. A, 112, 12337-44 (2008) S. Horvath, A. B. McCoy, B. M. Eliot, G. H. Weddle, J. R. Roscioli and M. A. Johnson, J. Phys. Chem. A, 115, 1556-68 (2010). A. B. McCoy, M. K. Sprague and M. Okumura, J. Phys. Chem. A, 115, 1324-33 (2010)

  12. Matrix composition and community structure analysis of a novel bacterial pyrite leaching community. (United States)

    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.

  13. Kinetics of the reaction between H· and superheated water probed with muonium

    International Nuclear Information System (INIS)

    Alcorn, Chris D.; Brodovitch, Jean-Claude; Percival, Paul W.; Smith, Marisa; Ghandi, Khashayar


    Highlights: • Rate constants for reactions of H with water resolve a controversy. • H reacts with superheated water via two channels. • The findings have important implications for the safety of some nuclear power reactors. - Abstract: Safe operation of supercritical water-cooled reactors requires knowledge of the kinetics of transient species formed by the radiolysis of water in the range 300–650 °C. Using muonium, it is possible to study aqueous H · atom chemistry over this temperature range. An important reaction to study is that of the H · atom with water itself, because it is a potential source of molecular H 2 . The concentration of H 2 is important to plant coolant chemistry, as H 2 is currently added to suppress oxidative corrosion in CANDU reactors. The reaction of muonium with H 2 O and D 2 O was studied experimentally up to 450 °C, and also via quantum chemical computations to investigate possible isotope effects. Our results suggest that although the H · atom abstraction from H 2 O is important at temperatures above 300 °C, the electron-producing channel (H · + H 2 O ⇌ H 3 O + + e aq - ) is significant at temperatures up to 300 °C, and becomes the dominant reaction channel at lower temperatures

  14. Theory of Ion and Water Transport in Reverse-Osmosis Membranes (United States)

    Oren, Y. S.; Biesheuvel, P. M.


    We present a theory for ion and water transport through reverse-osmosis (RO) membranes based on a Maxwell-Stefan framework combined with hydrodynamic theory for the reduced motion of particles in thin pores. We take into account all driving forces and frictions both on the fluid (water) and on the ions including ion-fluid friction and ion-wall friction. By including the acid-base characteristic of the carbonic acid system, the boric acid system, H3O+/OH- , and the membrane charge, we locally determine p H , the effective charge of the membrane, and the dissociation degree of carbonic acid and boric acid. We present calculation results for an experiment with fixed feed concentration, where effluent composition is a self-consistent function of fluxes through the membrane. A comparison with experimental results from literature for fluid flow vs pressure, and for salt and boron rejection, shows that our theory agrees very well with the available data. Our model is based on realistic assumptions for the effective size of the ions and makes use of a typical pore size of a commercial RO membrane.

  15. Construction of two novel indium phosphites with (3,6)- and (3,5)-connected frameworks: Synthesis, structure and characterization

    International Nuclear Information System (INIS)

    Li Huiduan; Zhang Lirong; Huo Qisheng; Liu Yunling


    Two novel anionic indium phosphites, formulated as [H 3 O][In(HPO 3 ) 2 ] (1) and [C 4 H 12 N 2 ][In 2 (HPO 3 ) 3 (C 2 O 4 )] (2), were prepared under hydrothermal conditions by using piperazine (PIP) as a structure-directing agent (SDA). Single-crystal X-ray diffraction analysis reveals that compounds 1 and 2 crystallize in the hexagonal space group P6 3 mc (No. 186) and orthorhombic space group Cmcm (No. 63), respectively. Compound 1, constructed from InO 6 octahedra and HPO 3 pseudo-pyramids, exhibits a rare (3,6)-connected layer structure with kgd (Kagome dual) topology. Compound 2, on the other hand, features a 3D phosphite-oxalate hybrid structure with intersecting 8- and 12-MRs channels. From a topological perspective 2 can be regarded as a (3, 5)-connected binodal net with the Schläfli symbol (4 2 .6)(4 2 .6 5 .8 3 ). Highlights: ► Two novel indium phosphite and indium phosphite-oxalate hybrid compounds are synthesized. ► (3, 6)-connected layer structure with kgd topology. ► (3,5)-connected binodal net with the Schläfli symbol (4 2 .6)(4 2 .6 5 .8 3 ).

  16. Experimental and Kinetic Modeling Study of C2H2Oxidation at High Pressure

    DEFF Research Database (Denmark)

    Lopez, Jorge Gimenez; Rasmussen, Christian Tihic; Hashemi, Hamid


    diagram for C2H3 + O2 by Goldsmith et al. and on new ab initio calculations, respectively. The C2H2 + HO2 reaction involves nine pressure- and temperature-dependent product channels, with formation of triplet CHCHO being dominant under most conditions. The barrier to reaction for C2H2 + O2 was found......A detailed chemical kinetic model for oxidation of acetylene at intermediate temperatures and high pressure has been developed and evaluated experimentally. The rate coefficients for the reactions of C2H2 with HO2 and O2 were investigated, based on the recent analysis of the potential energy...... to be more than 50 kcal mol−1 and predictions of the initiation temperature were not sensitive to this reaction. Experiments were conducted with C2H2/O2 mixtures highly diluted in N2 in a high-pressure flow reactor at 600–900 K and 60 bar, varying the reaction stoichiometry from very lean to fuel...

  17. Kinetics of hydrogen isotope exchange reactions

    International Nuclear Information System (INIS)

    Gold, V.; McAdam, M.E.


    Under the influence of tritium β-radiation, 1,4-dioxan undergoes hydrogen exchange with the solvent water. The inhibition of the reaction by known electron scavengers (Ag + , Cu 2+ , Ni 2+ , Co 2+ , Zn 2+ , H 3 + O) and also by species with high reactivity towards hydroxyl radicals but negligible reactivity towards solvated electrons (N 3 - , Br - , SCN - ) has been examined in detail. γ-irradiation similarly induces hydrogen exchange. The action of scavengers is interpreted as requiring the involvement of two separately scavengeable primary radiolysis products in the sequence of reactions leading to exchange. The presence of electron scavengers, even at high concentration, does not totally inhibit the exchange, and a secondary exchange route, involving a low vacancy state of inhibitor cations, is considered responsible for the 'unscavengeable' portion of the reaction, by providing an alternative exchange route. Analogies are drawn between the exchange reaction and other radiation-induced reactions that are thought to involve spur processes. Some implication of radiation-chemical studies in water-alcohol mixtures are indicated. (author)

  18. X-ray attenuation coefficient measurements for photon energies 4.508-13.375 keV in Cu, Cr and their compounds and the validity of the mixture rule

    International Nuclear Information System (INIS)

    Turgut, Ue.; Simsek, Oe.; Bueyuekkasap, E.; Ertugrul, M.


    To investigate the validity of the mixture rule which is used to compute the mass attenuation coefficients in compounds, the total mass attenuation coefficients for Cu, Cr elements and Cu 2 O, CuC 2 O 4 , CuCl 2 ·2H 2 O, Cu(C 2 H 3 O 2 ) 2 ·H 2 O, Cr 2 O 3 , Cr(NO 3 ) 3 , Cr 2 (SO 4 ) 3 ·H 2 O, Cr 3 (CH 3 CO 7 )(OH) 2 compounds were measured at photon energies between 4.508 and 13.375 keV by using the secondary excitation method. Ti, Mn, Fe, Ni, Zn, Ge, As, Rb elements were used as secondary exciters. 59.5 keV gamma rays emitted from an 241 Am annular source were used to excite the secondary exciters and Kα (K-L 3 , L 2 ) rays emitted from the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. Our measurements indicate that the mixture rule is not a suitable method for the computation of mass attenuation coefficients of compounds especially at an energy that is near the absorption edge. Obtained values were compared with theoretical values

  19. Experimental study of para- and ortho-H3+ recombination

    International Nuclear Information System (INIS)

    Plasil, R; Varju, J; Hejduk, M; Dohnal, P; KotrIk, T; Glosik, J


    Recombination of H 3 + with electrons is a key process for many plasmatic environments. Recent experiments on storage ring devices used ion sources producing H 3 + with enhanced populations of H 3 + ions in the para nuclear spin configuration to shed light on the theoretically predicted faster recombination of para states. Although increased recombination rates were observed, no in situ characterization of recombining ions was performed. We present a state selective recombination study of para- and ortho-H 3 + ions with electrons at 77 K in afterglow plasma in a He/Ar/H 2 gas-mixture. Both spin configurations of H 3 + have been observed in situ with a near infrared cavity ring down spectrometer (NIR-CRDS) using the two lowest energy levels of H 3 + . Using hydrogen with an enhanced population of H 2 molecules in para states allowed us to influence the [para-H 3 + ]/[ortho-H 3 + ] ratio in the discharge and in the afterglow. We observed an increase in the measured effective recombination rate coefficients with the increase of the fraction of para-H 3 + . Measurements with different fractions of para-H 3 + at otherwise identical conditions allowed us to determine the binary recombination rate coefficients for pure para-H 3 + p α bin (77 K) = (2.0±0.4)x10 -7 cm 3 s -1 and pure ortho-H 3 + o α bin (77 K) = (4±3)x10 -8 cm 3 s -1 .

  20. Piezoelectric Active Humidity Sensors Based on Lead-Free NaNbO3 Piezoelectric Nanofibers

    Directory of Open Access Journals (Sweden)

    Li Gu


    Full Text Available The development of micro-/nano-scaled energy harvesters and the self-powered sensor system has attracted great attention due to the miniaturization and integration of the micro-device. In this work, lead-free NaNbO3 piezoelectric nanofibers with a monoclinic perovskite structure were synthesized by the far-field electrospinning method. The flexible active humidity sensors were fabricated by transferring the nanofibers from silicon to a soft polymer substrate. The sensors exhibited outstanding piezoelectric energy-harvesting performance with output voltage up to 2 V during the vibration process. The output voltage generated by the NaNbO3 sensors exhibited a negative correlation with the environmental humidity varying from 5% to 80%, where the peak-to-peak value of the output voltage generated by the sensors decreased from 0.40 to 0.07 V. The sensor also exhibited a short response time, good selectively against ethanol steam, and great temperature stability. The piezoelectric active humidity sensing property could be attributed to the increased leakage current in the NaNbO3 nanofibers, which was generated due to proton hopping among the H3O+ groups in the absorbed H2O layers under the driving force of the piezoelectric potential.

  1. Effect of different solutions on electrochemical deposition of ZnO

    International Nuclear Information System (INIS)

    Asil, H.; Chinar, K.; Gur, E.; Tuzemen, S.


    ZnO thin films were grown by electrochemical deposition (ECD) onto indium tin oxide using different compounds such as Zn(NO 3 ) 2 , Zn(C 2 H 3 O 2 ) 2 , ZnCl 2 , Zn(ClO 4 ) 2 and different solvents such as dimethylsulfoxide (DMSO) and 18 M deionized water. Furthermore, solutions were prepared using different electrolytes and concentrations in order to determine the optimum deposition parameters of ZnO. All the grown films were characterized by X-ray diffraction, optical absorption and photoluminescence measurement techniques. It is indicated that films grown by using Zn(ClO 4 ) 2 show high crystallinity and optical quality. The X-ray diffraction analysis showed that ZnO thin films which were grown electrochemically in a non-aqueous solution (DMSO) prepared by Zn(ClO 4 ) 2 have highly c-axis preferential orientation. PL measurements showed that ZnO thin films grown in Zn(ClO 4 ) 2 indicates high quality emission characteristics compared to the thin films grown by other solutions

  2. Millimeter and submillimeter wave spectroscopy: molecules of astrophysical interest

    International Nuclear Information System (INIS)

    Plummer, G.M.


    Species of three general types of molecular ions were studied by means of millimeter-submillimeter (mm/sub-mm) wave spectroscopy. Because of their highly reactive nature, it has been possible to study ionic species in the microwave region for only the past ten is presented here. A new method is presented here for production of such molecular ions in concentrations greater by one to two orders of magnitude than possible with previous techniques, and the subsequent first mm/sub/mm/ detections of two isotopic forms of HCO + , three isotopic forms of ArD + , and the molecular ion H 3 O + . Simple neutral species, which are generally less reactive than ions, are also present in relatively large concentrations in the interstellar medium and in the atmospheres of cool stars themselves. Presented here is the first laboratory microwave detection of two isotopic species of LiH 2 , a solid at normal temperatures and pressures. In addition, a combined analysis of these data, additional data collected on the related species LiD, and existing data on LiD is presented. Finally, a large fraction of the mm/sub/mm/ emissions observed toward the interstellar medium were shown to belong to a small number of relatively heavy, stable, but spectroscopically complicated molecules, many of them internal rotors

  3. Comparison of toluene removal in air at atmospheric conditions by different corona discharges. (United States)

    Schiorlin, Milko; Marotta, Ester; Rea, Massimo; Paradisi, Cristina


    Different types of corona discharges, produced by DC of either polarity (+/-DC) and positive pulsed (+pulsed) high voltages, were applied to the removal of toluene via oxidation in air at room temperature and atmospheric pressure. Mechanistic insight was obtained through comparison of the three different corona regimes with regard to process efficiency, products, response to the presence of humidity and, for DC coronas, current/voltage characteristics coupled with ion analysis. Process efficiency increases in the order +DC toluene conversion and product selectivity were achieved, CO(2) and CO accounting for about 90% of all reacted carbon. Ion analysis, performed by APCI-MS (Atmospheric Pressure Chemical Ionization-Mass Spectrometry), provides a powerful rationale for interpreting current/voltage characteristics of DC coronas. All experimental findings are consistent with the proposal that in the case of +DC corona toluene oxidation is initiated by reactions with ions (O(2)(+*), H(3)O(+) and their hydrates, NO(+)) both in dry as well as in humid air. In contrast, with -DC no evidence is found for any significant reaction of toluene with negative ions. It is also concluded that in humid air OH radicals are involved in the initial stage of toluene oxidation induced both by -DC and +pulsed corona.

  4. Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions. (United States)

    Little, Brian K; Lockhart, PaviElle; Slaten, B L; Mills, G


    Photolysis of air-saturated aqueous solutions containing sulphonated poly(ether etherketone) and poly(vinyl alcohol) results in the generation of hydrogen peroxide. Consumption of oxygen and H2O2 formation are initially concurrent processes with a quantum yield of peroxide generation of 0.02 in stirred or unstirred solutions within the range of 7 ≤ pH ≤ 9. The results are rationalized in terms of O2 reduction by photogenerated α-hydroxy radicals of the polymeric ketone in competition with radical-radical processes that consume the macromolecular reducing agents. Generation of H2O2 is controlled by the photochemical transformation that produces the polymer radicals, which is most efficient in neutral and slightly alkaline solutions. Quenching of the excited state of the polyketone by both H3O(+) and OH(-) affect the yields of the reducing macromolecular radicals and of H2O2. Deprotonation of the α-hydroxy polymeric radicals at pH > 9 accelerate their decay and contribute to suppressing the peroxide yields in basic solutions. Maxima in [H2O2] are observed when illuminations are performed with static systems, where O2 reduction is faster than diffusion of oxygen into the solutions. Under such conditions H2O2 can compete with O2 for the reducing radicals resulting in a consumption of the peroxide.

  5. Adsorption of Cr(III) on ozonised activated carbon. Importance of Cpi-cation interactions. (United States)

    Rivera-Utrilla, J; Sánchez-Polo, M


    The adsorption of Cr(III) in aqueous solution was investigated on a series of ozonised activated carbons, analysing the effect of oxygenated surface groups on the adsorption process. A study was carried out to determine the adsorption isotherms and the influence of the pH on the adsorption of this metal. The adsorption capacity and affinity of the adsorbent for Cr(III) increased with the increase in oxygenated acid groups on the surface of the activated carbon. These findings imply that electrostatic-type interactions predominate in the adsorption process, although the adsorption of Cr(III) on the original (basic) carbon indicates that other forces also participate in the adsorption process. Thus, the ionic exchange of protons in the -Cpi-H3O(+) interaction for Cr(III) accounts for the adsorption of cationic species in basic carbons with positive charge density. Study of the influence of pH on the adsorption of Cr(III) showed that, in each system, the maximum adsorption occurred when the charge of the carbon surface was opposite that of the species of Cr(III) present at the pH of the experiment. These results confirmed that electrostatic interactions predominate in the adsorption process.

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

    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.

  7. Process for making 90 degree K. superconductors by impregnating cellulosic article with precursor solution

    International Nuclear Information System (INIS)

    Bolt, J.D.; Subramanian, M.A.


    This patent describes an improved process for preparing a shaped article of a superconducting composition having the formula MBa 2 Cu 3 O x wherein; M is selected from the group consisting of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu; x is from about 6.5 to about 7.0; the composition having a superconducting transition temperature of about 90 K. It comprises: forming in acetic acid a mixture of M(C 2 H 3 O 2 ) 3 , barium acetate and copper acetate in an atomic ratio of M:Ba:Cu of about 1:2:3; heating the resulting mixture to boiling, and adding sufficient formic acid to dissolve any undissolved starting material while continuing to boil the solution; contacting an article of cellulose material with the solution thereby impregnating the article with the solution, the article having the shape desired; removing excess solution from the resulting impregnated article of cellulose material and drying the impregnated article; heating the impregnated article of cellulose material to a temperature from about 850 degree C to about 925 degree C in an oxygen-containing atmosphere for a time sufficient to form MBa 2 Cu 3 O y , where y is from about 6.0 to about 6.5, the heating effecting carbonization of the cellulose material and oxidization of carbon without ignition; and maintaining the resulting article in an oxygen-containing atmosphere while cooling for a time sufficient to obtained the desired product

  8. Ion conduction mechanisms and thermal properties of hydrated and anhydrous phosphoric acids studied with 1H, 2H, and 31P NMR. (United States)

    Aihara, Yuichi; Sonai, Atsuo; Hattori, Mineyuki; Hayamizu, Kikuko


    To understand the behaviors of phosphoric acids in fuel cells, the ion conduction mechanisms of phosphoric acids in condensed states without free water and in a monomer state with water were studied by measuring the ionic conductivity (sigma) using AC impedance, thermal properties, and self-diffusion coefficients (D) and spin-lattice relaxation times (T1) with multinuclear NMR. The self-diffusion coefficient of the protons (H+ or H3O+), H2O, and H located around the phosphate were always larger than the diffusion coefficients of the phosphates and the disparity increased with increasing phosphate concentration. The diffusion coefficients of the samples containing D2O paralleled those in the protonated samples. Since the 1H NMR T1 values exhibited a minimum with temperature, it was possible to determine the correlation times and they were found to be of nanosecond order for a distance of nanometer order for a flip. The agreement of the ionic conductivities measured directly and those calculated from the diffusion coefficients indicates that the ion conduction obeys the Nernst-Einstein equation in the condensed phosphoric acids. The proton diffusion plays a dominant role in the ion conduction, especially in the condensed phosphoric acids.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Poly[(μ3-benzene-1,3,5-tricarboxylato-κ3O1:O3:O5(μ2-2-methylimidazolato-κ2N:N′tris(2-methylimidazole-κNdizinc(II

    Directory of Open Access Journals (Sweden)

    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.

  12. Novel protonated and hydrated n=1 Ruddlesden-Popper phases, HxNa1-xLaTiO4.yH2O, formed by ion-exchange/intercalation reaction

    International Nuclear Information System (INIS)

    Nishimoto, Shunsuke; Matsuda, Motohide; Miyake, Michihiro


    New derivatives of layered perovskite compounds with H 3 O + ions, H + ions and water molecules in the interlayer, H x Na 1-x LaTiO 4 .yH 2 O, were successfully synthesized by an ion-exchange/intercalation reaction with dilute HCl solution, using an n=1 member of Ruddlesden-Popper phase, NaLaTiO 4 . Powder X-ray diffraction revealed that the layered structure changed from space group P4/nmm with a=3.776(1) and c=13.028(5)A to I4/mmm with a=3.7533(3) and c=28.103(4)A after the ion-exchange/intercalation reaction at pH 5. The change of space group indicates that the perovskite layers are transformed from staggered to an eclipsed configuration through the ion-exchange/intercalation reaction. Thermogravimetric analysis and high-temperature powder X-ray diffraction suggested the existence of the secondary hydrated phase by dehydrating H x Na 1-x LaTiO 4 .yH 2 O at 100 o C

  13. Kinetic study of the thorium phosphate - diphosphate dissolution

    International Nuclear Information System (INIS)

    Dacheux, N.; Thomas, A.C.; Brandel, V.; Genet, M.


    The thorium phosphate-diphosphate Th 4 (PO 4 ) 4 P 2 O 7 (TPD) structure allows the replacement of large amounts of thorium by tetravalent actinides leading to the formation of solid solutions. This compound was obtained in powdered or sintered form after pressing at room temperature at 300-800 MPa then heating at 1250 deg. C for 10-30 hours. The resistance of this material to aqueous corrosion was determined by varying several parameters such as surface, leaching flow, acidity or temperature. It was thus possible to independently determine the influence of each parameter on the leaching rate provided that the saturation of the solution was not obtained. In acidic media, the partial order related to [H 3 O + ] was found to be in the 0.31-0.35 range while, in basic media, the partial order related to [OH - ] was almost the same (0.45). The activation energy (42 kJ/mol) was determined between 4 deg. C and 120 deg. C. Moreover, the addition of phosphate in the leachate slightly increased the TPD dissolution rate. When the saturation of the solution is reached, a gelatinous precipitate controls the thorium and phosphate concentrations. The complete characterization of this solid led to the proposed general formula Th 2 (PO 4 ) 2 (HPO 4 ). n H 2 O which conventional solubility product (at I = 0 M) is very low: K * S,0 10 -66.6±1.2 even in very acidic media. (authors)

  14. Hyperthermal (1-100 eV) nitrogen ion scattering damage to D-ribose and 2-deoxy-D-ribose films. (United States)

    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.

  15. An experimental screen for quinoline/fumaric acid salts and co-crystals

    DEFF Research Database (Denmark)

    Beko, S. L.; Schmidt, M. U.; Bond, A. D.


    . Characterised products include the previously published 1 : 1 salt, C9H8N+center dot C4H3O4-, and a new 2 : 1 quinoline/fumaric acid co-crystal, (C9H7N)(2)center dot C4H4O4. Attempts to influence the crystallisation outcome by addition of 6-methylquinoline yielded a second co-crystal, also with an inherent 2......An experimental screen has been carried out for salts and co-crystals of quinoline (C9H7N) and fumaric acid (C4H4O4), including solution-based co-crystallisation from a variety of solvents, solvent-assisted and solvent-free co-grinding, and direct co-crystallisation of the starting materials...... : 1 quinoline/fumaric acid ratio, as a solid solution containing ca. 75% 6-methylquinoline and 25% quinoline. The corresponding co-crystal with pure 6-methylquinoline, (C10H9N)(2)center dot C4H4O4, was prepared, but the analogous structure with pure quinoline could not be obtained. Energy minimisation...

  16. Multi-photon ionization of atoms and molecules by intense XUV-FEL light. Application to methanol and ethanol molecules

    International Nuclear Information System (INIS)

    Sato, Takahiro; Iwasaki, Atsushi; Okino, Tomoya; Yamanouchi, Kaoru; Yagishita, Akira; Yazawa, Hiroki; Kannari, Fumihiko; Aoyama, Makoto; Yamakawa, Koichi; Midorikawa, Katsumi; Nakano, Hidetoshi; Yabashi, Makina; Nagasono, Mitsuru; Higashiya, Atsushi; Togashi, Tadashi; Ishikawa, Tetsuya


    The photo-ionization processes of methanol (CH 3 OH, CD 3 OH) and ethanol (C 2 H 5 OH) and their dependences on the wavelength and the light-field intensity were investigated using intense XUV light at 51 and 61 nm at the XUV free electron laser facility of RIKEN SPring-8 Center. The light field intensity achieved at 51 nm was found to be intense enough to generate Ar 7+ from Ar. It was confirmed that (1) the stable dications, CH 2 OH 2+ and CH 2 OD 2+ , were produced respectively from CH 3 OH and CD 3 OH, and C 2 H 2 OH 2+ from CH 2 H 5 OH via the direct and/or stepwise two-photon absorption, and (2) C + and CH + were produced from C 2 H 5 OH via the stepwise two-photon absorption of the XUV light. It was also confirmed by the formation of H 3 O + from CH 3 OH and C 2 H 5 OH, and HOD 2 + from CD 3 OH that hydrogen migration processes were induced by the irradiation of the intense XUV light. (author)

  17. A metabolic fingerprinting approach based on selected ion flow tube mass spectrometry (SIFT-MS) and chemometrics: A reliable tool for Mediterranean origin-labeled olive oils authentication. (United States)

    Bajoub, Aadil; Medina-Rodríguez, Santiago; Ajal, El Amine; Cuadros-Rodríguez, Luis; Monasterio, Romina Paula; Vercammen, Joeri; Fernández-Gutiérrez, Alberto; Carrasco-Pancorbo, Alegría


    Selected Ion flow tube mass spectrometry (SIFT-MS) in combination with chemometrics was used to authenticate the geographical origin of Mediterranean virgin olive oils (VOOs) produced under geographical origin labels. In particular, 130 oil samples from six different Mediterranean regions (Kalamata (Greece); Toscana (Italy); Meknès and Tyout (Morocco); and Priego de Córdoba and Baena (Spain)) were considered. The headspace volatile fingerprints were measured by SIFT-MS in full scan with H 3 O + , NO + and O 2 + as precursor ions and the results were subjected to chemometric treatments. Principal Component Analysis (PCA) was used for preliminary multivariate data analysis and Partial Least Squares-Discriminant Analysis (PLS-DA) was applied to build different models (considering the three reagent ions) to classify samples according to the country of origin and regions (within the same country). The multi-class PLS-DA models showed very good performance in terms of fitting accuracy (98.90-100%) and prediction accuracy (96.70-100% accuracy for cross validation and 97.30-100% accuracy for external validation (test set)). Considering the two-class PLS-DA models, the one for the Spanish samples showed 100% sensitivity, specificity and accuracy in calibration, cross validation and external validation; the model for Moroccan oils also showed very satisfactory results (with perfect scores for almost every parameter in all the cases). Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Infrared spectroscopy of the acetyl cation and its protonated ketene isomer (United States)

    Mosley, J. D.; Young, J. W.; Duncan, M. A.


    [C2,H3,O]+ ions are generated with a pulsed discharge in a supersonic expansion containing methyl acetate or acetone. These ions are mass selected and their infrared spectra are recorded via laser photodissociation and the method of argon tagging. Computational chemistry is employed to investigate structural isomers and their spectra. The acetyl cation (CH3CO+) is the global minimum and protonated ketene (CH2COH+) is the next lowest energy isomer (+176.2 kJ/mol). When methyl acetate is employed as the precursor, the infrared spectrum reveals that only the acetyl cation is formed. Partially resolved rotational structure reveals rotation about the C3 axis. When acetone is used as the precursor, acetyl is still the most abundant cation, but there is also a minor component of protonated ketene. Computations reveal a significant barrier to interconversion between the two isomers (+221 kJ/mol), indicating that protonated ketene must be obtained via kinetic trapping. Both isomers may be present in interstellar environments, and their implications for astrochemistry are discussed.

  19. An (e, 2e + ion) study of low-energy electron-impact ionization and fragmentation of tetrahydrofuran with high mass and energy resolutions (United States)

    Ren, Xueguang; Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yoon; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander


    We study the low-energy (E0 = 26 eV) electron-impact induced ionization and fragmentation of tetrahydrofuran using a reaction microscope. All three final-state charged particles, i.e., two outgoing electrons and one fragment ion, are detected in triple coincidence such that the momentum vectors and, consequently, the kinetic energies for charged reaction products are determined. The ionic fragments are clearly identified in the experiment with a mass resolution of 1 amu. The fragmentation pathways of tetrahydrofuran are investigated by measuring the ion kinetic energy spectra and the binding energy spectra where an energy resolution of 1.5 eV has been achieved using the recently developed photoemission electron source. Here, we will discuss the fragmentation reactions for the cations C4H8O+, C4H7O+, C2H3O+, C3H_6^+, C3H_5^+, C3H_3^+, CH3O+, CHO+, and C2H_3^+.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. A Molecular Dynamic Simulation of Hydrated Proton Transfer in Perfluorosulfonate Ionomer Membranes (Nafion 117

    Directory of Open Access Journals (Sweden)

    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.

  2. Regeneration of cello-oligomers via selective depolymerization of cellulose fibers derived from printed paper wastes. (United States)

    Voon, Lee Ken; Pang, Suh Cem; Chin, Suk Fun


    Cellulose extracted from printed paper wastes were selectively depolymerized under controlled conditions into cello-oligomers of controllable chain lengths via dissolution in an ionic liquid, 1-allyl-3-methylimidazolium chloride (AMIMCl), and in the presence of an acid catalyst, Amberlyst 15DRY. The depolymerization process was optimized against reaction temperature, concentration of acid catalyst, and reaction time. Despite rapid initial depolymerization process, the rate of cellulose depolymerization slowed down gradually upon prolonged reaction time, with 75.0 wt% yield of regenerated cello-oligomers (mean Viscosimetric Degree of Polymerization value of 81) obtained after 40 min. The depolymerization of cellulose fibers at 80 °C appeared to proceed via a second-order kinetic reaction with respect to the catalyst concentration of 0.23 mmol H3O(+). As such, the cellulose depolymerization process could afford some degree of control on the degree of polymerization or chain lengths of cello-oligomers formed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Coupling an electrospray source and a solids probe/chemical ionization source to a selected ion flow tube apparatus

    International Nuclear Information System (INIS)

    Melko, Joshua J.; Ard, Shaun G.; Shuman, Nicholas S.; Viggiano, Albert A.; Pedder, Randall E.; Taormina, Christopher R.


    A new ion source region has been constructed and attached to a variable temperature selected ion flow tube. The source features the capabilities of electron impact, chemical ionization, a solids probe, and electrospray ionization. The performance of the instrument is demonstrated through a series of reactions from ions created in each of the new source regions. The chemical ionization source is able to create H 3 O + , but not as efficiently as similar sources with larger apertures. The ability of this source to support a solids probe, however, greatly expands our capabilities. A variety of rhenium cations and dications are created from the solids probe in sufficient abundance to study in the flow tube. The reaction of Re + with O 2 proceeds with a rate constant that agrees with the literature measurements, while the reaction of Re 2 2+ is found to charge transfer with O 2 at about 60% of the collision rate; we have also performed calculations that support the charge transfer pathway. The electrospray source is used to create Ba + , which is reacted with N 2 O to create BaO + , and we find a rate constant that agrees with the literature

  4. Multifunctional uranyl hybrid materials: structural diversities as a function of pH, luminescence with potential nitrobenzene sensing, and photoelectric behavior as p-type semiconductors. (United States)

    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.

  5. The diversity of five metal-organic complexes based on an unsymmetrical biphenyl tetracarboxylate: Synthesis, structures, magnetism and luminescence (United States)

    Feng, Si-si; Xie, Ling; Lu, Li-ping; Zhu, Miao-li; Su, Feng


    Careful investigation of the effects of metal ions and pH value resulted in five multi-dimensional metal-organic complexes, [Co5(μ3-OH)2(α-bptc)2(H2O)6]n (1), {(H3O)2[Co4(μ3-O)(α-bptc)2(H2O)]·4H2O}n (2), {K2[Zn4(μ3-OH)2(α-bptc)2(H2O)3]}n (3), [Zn4(α-bptc)2(H2O)3]n (4), and {[Cd4(α-bptc)2(H2O)7]·2H2O}n (5) (α-H4bptc = 2,3,3',4'-biphenyl tetracarboxylic acid). The complexes consisted of different highly connected secondary building units (SBUs) assembled via hydrothermal in situ routes. The pH value as well as the kinds of metal ions influenced the coordination modes of α-H4bptc and also introduced the hydroxyl ligand at high pH value, resulting in the diversity of SBUs and dimensionality. Variable temperature magnetic measurements indicated the antiferromagnetic behavior in the Co5 core in 1, and the intra-chain ferrimagnetic behavior in complex 2. Moreover, the luminescent properties of the complexes 3-5 indicated the existence of intra-ligand charge transfer.

  6. Ab initio study of the O4H(+) novel species: spectroscopic fingerprints to aid its observation. (United States)

    Xavier, F George D; Hernández-Lamoneda, Rámon


    A detailed ab initio characterization of the structural, energetic and spectroscopic properties of the novel O4H(+) species is presented. The equilibrium structures and relative energies of all multiplet states have been determined systematically by analyzing static and dynamical correlation effects. The two and three body dissociation processes have been studied and indicate the presence of conical intersections in various states including the ground state. Comparison with available thermochemical data is very good, supporting the applied methodology. The reaction, H3(+) + O4→ O4H(+) + H2, was found to be exothermic ΔH = -19.4 kcal mol(-1) and therefore, it is proposed that the product in the singlet state could be formed in the interstellar medium (ISM) via collision processes. To aid in its laboratory or radioastronomy detection in the interstellar medium we determined spectroscopic fingerprints. It is estimated for the most stable geometry of O4H(+) dipole allowed electronic transitions in the visible region at 429 nm and 666 nm, an intense band at 1745 cm(-1) in the infrared and signals at 40.6, 81.2 and 139.2 GHz in the microwave region at 10, 50 and 150 K respectively, relevant for detection in the ISM.

  7. Aggregation-induced chemical reactions: acid dissociation in growing water clusters. (United States)

    Forbert, Harald; Masia, Marco; Kaczmarek-Kedziera, Anna; Nair, Nisanth N; Marx, Dominik


    Understanding chemical reactivity at ultracold conditions, thus enabling molecular syntheses via interstellar and atmospheric processes, is a key issue in cryochemistry. In particular, acid dissociation and proton transfer reactions are ubiquitous in aqueous microsolvation environments. Here, the full dissociation of a HCl molecule upon stepwise solvation by a small number of water molecules at low temperatures, as relevant to helium nanodroplet isolation (HENDI) spectroscopy, is analyzed in mechanistic detail. It is found that upon successive aggregation of HCl with H(2)O molecules, a series of cyclic heteromolecular structures, up to and including HCl(H(2)O)(3), are initially obtained before a precursor state for dissociation, HCl(H(2)O)(3)···H(2)O, is observed upon addition of a fourth water molecule. The latter partially aggregated structure can be viewed as an "activated species", which readily leads to dissociation of HCl and to the formation of a solvent-shared ion pair, H(3)O(+)(H(2)O)(3)Cl(-). Overall, the process is mostly downhill in potential energy, and, in addition, small remaining barriers are overcome by using kinetic energy released as a result of forming hydrogen bonds due to aggregation. The associated barrier is not ruled by thermal equilibrium but is generated by athermal non-equilibrium dynamics. These "aggregation-induced chemical reactions" are expected to be of broad relevance to chemistry at ultralow temperature much beyond HENDI spectroscopy.

  8. A procedure for batch separation of 14C-hexose from 14C-sucrose

    International Nuclear Information System (INIS)

    Tarpley, L.; Vietor, D.M.


    This presentation describes a method for separating 14 C-hexose from 14 C-sucrose in extracts of plant tissue. Portions of ethanol extracts are treated with activated charcoal in microcentrifuge tubes. Aliquots are removed, ethanol evaporated and replaced with reaction mixture that phosphorylates hexose (HEPPS, K 2 HPO 4 , Mg(C 2 H 3 O 2 ) 2 , ovalbumen, Na 2 ATP, yeast hexokinase). After a time course, the hexokinase reaction is stopped (slowed considerably) to minimize effects of contamination enzyme activities. The stopping agent used is lyxose, a nonphosphorylable analogue of glucose. The strong anionic charge of phosphate introduced through the hexokinase action results in binding (> 95%) of hexose-phosphate to anion-exchange resin. Sucrose remains unbound (> 95%) in solution. This batch ion-exchange is performed in microcentrifuge tubes to allow many samples to be processed simultaneously. Recovery of radiolabel in extracts is complete (99%), and determinations are repeatable (cv = 23%). This method for routinely separating and quantifying 14 C-hexose and 14 C-sucrose in plant tissue extracts can contribute to the economy and feasibility of studies of 14 C-photoassimilate partitioning to soluble sugars within and among plant tissues

  9. Quantification of the simple and double strand breaks following the disintegration of iodine-125 in situ in chromosomal fiber

    International Nuclear Information System (INIS)

    Oudira, H.; Saifi, A.


    The principal objective of this study is to compare the radiochemical yields of the simple and double strand breaks (C.S.B. and C.D.B.) generated in the propellers of the molecule of DNA, following the taking in consideration of two electronic spectra of disintegration of iodine-125. Indeed, the combined use of the Monte Carlo method of the type step by step and the equation of diffusion (∂ C i / ∂ t = D i Δ 2 C i + S) makes it possible to simulate the transport of the electrons, and the chemical reactions due to the diffusion of the entities created throughout the physico-chemical and chemical process considered (e-aq, H, OH, H 2 , H 2 O 2 , and H 3 O + ). In this study, we take in consideration a complex model of DNA (nucleosome) and its envelope of hydration like we also take in consideration of the radio-protector effect of the inhibitors such as the Formiat (Formiat the sodium, HCOO - ). Moreover, the comparison of our results to those obtained by other models, highlights on one hand an unquestionable agreement and on the other hand the power and the capacity of adaptation of the codes worked out to various models of DNA. (authors)

  10. Water Formation and Destruction by 'Super' X-ray Flares from a T-Tauri Star in a Protoplanetary Disk (United States)

    Waggoner, Abygail R.; Cleeves, L. Ilsedore


    We present models of H2O chemistry is protoplanetary disks in the presence of 'super' X-ray flares emitted by a T-Tauri star. We examine the time-evolving chemistry of H2O at radial locations from 1 to 20 AU at various vertical heights from the mid-plane to the surface of the disk. We find the gas-phase H2O abundance can be enhanced in the surface (Z/R ≥ 0.3) by more than a factor of approximately 3 - 5 by strong flares, i.e., those that increase the ionization rate by a factor of 100. Dissociative recombination of H3O+ , H2O adsorption onto grain, and photolysis of H2O are found to be the three dominant processes leading to a change in H2O abundance. We find X-ray flares have predominantly short- term (days) effects on gaseous H2O abundance, but some regions show a long-term (for the duration of the test about 15 days) decrease in gaseous H2O due to adsorption onto grains, which results in an increase (up to 200%) in ice H2O in regions where ice H2O is 10-8 abundance no are response in the ice is observed.Thanks to the National Science Foundation for funding this research as a part of the Smithsonian Astrophysical Observatory Research Experience for Undergraduates (SAO REU).

  11. Alpha spectrometry and the secondary ion mass spectrometry of thorium

    International Nuclear Information System (INIS)

    Strisovska, J.; Kuruc, J.; Galanda, D.; Matel, L.; Aranyosiova, M.; Velic, D.


    The main objective of this master thesis was preparation of samples with thorium content on the steel discs by electrodeposition for determination of natural thorium isotope by alpha spectrometry and the secondary ion mass spectrometry and finding out their possible linear correlation between these methods. The samples with electrolytically excluded isotope of 232 Th were prepared by electrodeposition from solution Th(NO 3 ) 4 ·12 H2 O on steel discs in electrodeposition cell with use of solutions Na 2 SO 4 , NaHSO 4 , KOH and (NH 4 ) 2 (C 2 O 4 ) by electric current 0.75 A. Discs were measured by alpha spectrometer. Activity was calculated from the registered impulses for 232 Th and surface's weight. After alpha spectrometry measurements discs were analyzed by TOF-SIMS IV which is installed in the International Laser Centre in Bratislava. Intensities of isotope of 232 Th and ions of ThO + , ThOH + , ThO 2 H + , Th 2 O 4 H + , ThO 2 - , ThO 3 H - , ThH 3 O 3 - and ThN 2 O 5 H - were identified. The linear correlation is between surface's weights of Th and intensities of ions of Th + from SIMS, however the correlation coefficient has relatively low value. We found out with SIMS method that oxidized and hydride forms of thorium are significantly represented in samples with electroplated thorium. (authors)

  12. High Energy Ion Beam Studies of Ion Exchange in a Na2O-Al2O3-SiO2 Glass

    International Nuclear Information System (INIS)

    Shutthanadan, Vaithiyalingam; Baer, Donald R.; Thevuthasan, Suntharampillai; Adams, Evan M.; Maheswaran, Saravanamuthu; Engelhard, Mark H.; Icenhower, Jonathan P.; McGrail, Bernard P.


    As part of understanding the processes leading to sodium release and ion exchange, the surface and near surface reaction regions on several specimens of a Na2O-Al2O3-SiO2 glass have been examined after exposures to isotopically labeled aqueous solutions. The majority of the analyses describe here have been carried out using energetic ion beam analysis. Rutherford backscattering spectrometry (RBS) has been used to measure the overall glass composition and to determine the profiles and amounts of Na released from the surface. An important part of the ion exchange process is the uptake and incorporation of hydrogen and oxygen in the glass from the solution. To facilitate this analysis, the glasses were exposed to a solution containing 18O and deuterium and analyzed by accelerator based nuclear reaction analysis (NRA). To confirm some of the RBS depth profile data very near the surface, XPS depth profiles were collected on some samples. Although the Na concentration is decreased in the near surface region, it is not totally removed from the outer surface. In this same region, there is also a significant amount of 18O incorporated demonstrating considerable interaction between the water and the glass. Deeper into the material the amounts of deuterium and 18O are more consistent with water or H3O+ diffusion. These results suggest that there exist an outer reaction layer and an inner diffusion controlled layer in the surface region of the reacted glass

  13. SFG study of platinum electrodes in perchloric acid solutions (United States)

    Zheng, W. Q.; Pluchery, O.; Tadjeddine, A.


    Infrared-visible sum-frequency generation (SFG) spectroscopy has been used to study the structure of water molecules (and/or its derivatives OH -, H 3O + etc.) at aqueous electrolyte/electrode interfaces. For Pt(1 1 0) and Pt(1 0 0) electrodes in 0.1 M perchloric acid solution, we did not observe any significant O-H stretching resonance. In striking contrast to the resonant SFG signal, the nonresonant SFG (NRSFG) signal varies sensitively with the applied electrochemical potential, indicating that the interaction of water molecules with platinum electrodes is relatively weak as compared to that of H + and ClO 4- ions. From changes in the NRSFG signal and on the basis of an ionic adsorption model, we can also deduce that the potential of zero charge of Pt(1 1 0) in 0.1 M HClO 4 should be located at about 0.22 V (vs. NHE). This value is in good agreement with that measured recently by electrochemical method.

  14. Microscopic dynamics of charge separation at the aqueous electrochemical interface. (United States)

    Kattirtzi, John A; Limmer, David T; Willard, Adam P


    We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water-metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali-halide pair, Na + I - , or classical ions, and the products of water autoionization, H 3 O + OH - , or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water's collective role in the process, is conserved between the bulk liquid and the electrode interface. However, the thermodynamic and kinetic details of the process differ between these two environments in a way that depends on ion type. In the case of the classical ion pairs, a higher free-energy barrier to charge separation and a smaller flux over that barrier at the interface result in a rate of dissociation that is 40 times slower relative to the bulk. For water ions, a slightly higher free-energy barrier is offset by a higher flux over the barrier from longer lived hydrogen-bonding patterns at the interface, resulting in a rate of association that is similar both at and away from the interface. We find that these differences in rates and stabilities of charge separation are due to the altered ability of water to solvate and reorganize in the vicinity of the metal interface.

  15. Toward elimination of discrepancies between theory and experiment: The rate constant of the atmospheric conversion of SO3 to H2SO4 (United States)

    Loerting, Thomas; Liedl, Klaus R.


    The hydration rate constant of sulfur trioxide to sulfuric acid is shown to depend sensitively on water vapor pressure. In the 1:1 SO3-H2O complex, the rate is predicted to be slower by about 25 orders of magnitude compared with laboratory results [Lovejoy, E. R., Hanson, D. R. & Huey, L. G. (1996) J. Phys. Chem. 100, 19911–19916; Jayne, J. T., Pöschl, U., Chen, Y.-m., Dai, D., Molina, L. T., Worsnop, D. R., Kolb, C. E. & Molina, M. J. (1997) J. Phys. Chem. A 101, 10000–10011]. This discrepancy is removed mostly by allowing a second and third water molecule to participate. An asynchronous water-mediated double proton transfer concerted with the nucleophilic attack and a double proton transfer accompanied by a transient H3O+ rotation are predicted to be the fastest reaction mechanisms. Comparison of the predicted negative apparent “activation” energies with the experimental finding indicates that in our atmosphere, different reaction paths involving two and three water molecules are taken in the process of forming sulfate aerosols and consequently acid rain. PMID:10922048

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

    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.

  17. Influence of γ-radiation on the reactivity of montmorillonite towards H2O2

    International Nuclear Information System (INIS)

    Holmboe, Michael; Jonsson, Mats; Wold, Susanna


    Compacted and water saturated bentonite will be used as an engineered barrier in deep geological repositories for radioactive waste in many countries. Due to the high dose rate of ionizing radiation outside the canisters holding the nuclear waste, radiolysis of the interlayer and pore water in the compacted bentonite is unavoidable. Upon reaction with the oxidizing and reducing species formed by water radiolysis (OH • , e − (aq) , H • , H 2 O 2 , H 2 , HO 2 • , H 3 O + ), the overall redox properties in the bentonite barrier may change. In this study the influence of γ-radiation on the structural Fe(II)/Fe Tot ratio in montmorillonite and its reactivity towards hydrogen peroxide (H 2 O 2 ) was investigated in parallel experiments. The results show that under anoxic conditions the structural Fe(II)/Fe Tot ratio of dispersed Montmorillonite increased from ≤3 to 25–30% after γ-doses comparable to repository conditions. Furthermore, a strong correlation between the structural Fe(II)/Fe Tot ratio and the H 2 O 2 decomposition rate in montmorillonite dispersions was found. This correlation was further verified in experiments with consecutive H 2 O 2 additions, since the structural Fe(II)/Fe Tot ratio was seen to decrease concordantly. This work shows that the structural iron in montmorillonite could be a sink for one of the major oxidants formed upon water radiolysis in the bentonite barrier, H 2 O 2 .

  18. Radioenzymatic assay of DOPA (3,4-dihydroxyphenylalanine)

    International Nuclear Information System (INIS)

    Johnson, G.A.; Gren, J.M.; Kupiecki, R.


    We modified the single-isotope radioenzymatic assay for catecholamines [Life Sci. 21, 625(1977)] to assay 3,4-dihydroxyphenylalanine (DOPA). DOPA decarboxylase is used to convert DOPA to dopamine, which concurrently is converted to [ 3 H]-3-O-methyldopamine in the presence of catechol-O-methyltransferase and [methyl- 3 H]-S-adenosylmethionine and assayed radioenzymatically. For assay of plasma DOPA, 50 μl of untreated plasma is added directly into the incubation mixture. A duplicate mixture containing an internal standard requires a second 50-μl aliquot of plasma. Because the assay measures both DOPA and endogenous dopamine, two additional aliquots of plasma must be assayed for dopamine in the absence of the decarboxylase by the differential assay; DOPA is estimated by difference. The assay is sensitive to 25 pg (500 ng/liter of plasma). Analysis of DOPA (DOPA plus dopamine) and the concurrent differential assay of catecholamines in at least 10 samples can be done in a single working day. Plasma DOPA concentrations for 42 normotensive adults were 1430 +- 19 ng/liter (mean +- SEM). In contrast, dopamine concentrations for these same subjects averaged 23 +- 20 ng/liter. Values for the 24 women subjects (1510 +- 62 ng/liter) significantly (P = 0.04) exceeded those for the men

  19. MOFzyme: Intrinsic protease-like activity of Cu-MOF (United States)

    Li, Bin; Chen, Daomei; Wang, Jiaqiang; Yan, Zhiying; Jiang, Liang; Deliang Duan; He, Jiao; Luo, Zhongrui; Zhang, Jinping; Yuan, Fagui


    The construction of efficient enzyme mimetics for the hydrolysis of peptide bonds in proteins is challenging due to the high stability of peptide bonds and the importance of proteases in biology and industry. Metal-organic frameworks (MOFs) consisting of infinite crystalline lattices with metal clusters and organic linkers may provide opportunities for protease mimic which has remained unknown. Herein, we report that Cu2(C9H3O6)4/3 MOF (which is well known as HKUST-1 and denoted as Cu-MOF here), possesses an intrinsic enzyme mimicking activity similar to that found in natural trypsin to bovine serum albumin (BSA) and casein. The Michaelis constant (Km) of Cu-MOF is about 26,000-fold smaller than that of free trypsin indicating a much higher affinity of BSA for Cu-MOF surface. Cu-MOF also exhibited significantly higher catalytic efficiency than homogeneous artificial metalloprotease Cu(II) complexes and could be reused for ten times without losing in its activity. Moreover, Cu-MOF was successfully used to simulate trypsinization in cell culture since it dissociated cells in culture even without EDTA.

  20. The OH + D2 --> HOD + D angle-velocity distribution: quasi-classical trajectory calculations on the YZCL2 and WSLFH potential energy surfaces and comparison with experiments at ET = 0.28 eV. (United States)

    Sierra, José Daniel; Martínez, Rodrigo; Hernando, Jordi; González, Miguel


    The angle-velocity distribution (HOD) of the OH + D(2) reaction at a relative translational energy of 0.28 eV has been calculated using the quasi-classical trajectory (QCT) method on the two most recent potential energy surfaces available (YZCL2 and WSLFH PESs), widely extending a previous investigation of our group. Comparison with the high resolution experiments of Davis and co-workers (Science, 2000, 290, 958) shows that the structures (peaks) found in the relative translational energy distributions of products could not be satisfactorily reproduced in the calculations, probably due to the classical nature of the QCT method and the importance of quantum effects. The calculations, however, worked quite well for other properties. Overall, both surfaces led to similar results, although the YZCL2 surface is more accurate to describe the H(3)O PES, as derived from comparison with high level ab initio results. The differences observed in the QCT calculations were interpreted considering the somewhat larger anisotropy of the YZCL2 PES when compared with the WSLFH PES.

  1. Microstructures of the Sulfonic Acid-Functionalized Ionic Liquid/Sulfuric Acid and Their Interactions: A Perspective from the Isobutane Alkylation. (United States)

    Zheng, Weizhong; Huang, Chizhou; Sun, Weizhen; Zhao, Ling


    The all-atom force field for concentrated sulfuric acid (98.30 wt %) was developed in this work based on ab initio calculations. The structural and dynamical properties of sulfuric acid and the mixing behaviors of sulfuric acid with ionic liquids (ILs), i.e., SFIL (1-methyl-3-(propyl-3-sulfonate) imidazolium bisulfate ([PSMim][HSO 4 ])) and non-SFIL (1-methyl-3-propyl imidazolium bisulfate ([PMim][HSO 4 ])), were investigated using a molecular dynamics simulation. For sulfuric acid, most H 3 O + ions were found beside HSO 4 - ions, forming a contact ion pair with the HSO 4 - ions, and three-dimensional hydrogen-bonding networks existed in the sulfuric acid. Analyses indicate that both ILs could be miscible with sulfuric acid with a strong exothermic character. The new strong interaction site between the sulfonic acid group of SFIL and an H 2 SO 4 molecule through a strong hydrogen-bonding interaction was observed, which was beneficial to the catalytic activity and stability of the sulfuric acid. This observation is in good agreement with the experimental results that indicate SFILs could enhance the reusability of sulfuric acid for the isobutane alkylation about 4-fold compared to that of non-SFILs. Hopefully this work will provide insights into the screening and designing of new isobutane alkylation catalysts based on sulfuric acid and SFILs.

  2. The ionosphere of Europa from Galileo radio occultations (United States)

    Kliore, A. J.; Hinson, D. P.; Flasar, F. M.; Nagy, A. F.; Cravens, T. E.


    The Galileo spacecraft performed six radio occultation observations of Jupiter's Galilean satellite Europa during its tour of the jovian system. In five of the six instances, these occultations revealed the presence of a tenuous ionosphere on Europa, with an average maximum electron density of nearly 10(4) per cubic centimeter near the surface and a plasma scale height of about 240 +/- 40 kilometers from the surface to 300 kilometers and of 440 +/- 60 kilometers above 300 kilometers. Such an ionosphere could be produced by solar photoionization and jovian magnetospheric particle impact in an atmosphere having a surface density of about 10(8) electrons per cubic centimeter. If this atmosphere is composed primarily of O2, then the principal ion is O2+ and the neutral atmosphere temperature implied by the 240-kilometer scale height is about 600 kelvin. If it is composed of H2O, the principal ion is H3O+ and the neutral temperature is about 340 kelvin. In either case, these temperatures are much higher than those observed on Europa's surface, and an external heating source from the jovian magnetosphere is required.

  3. Excimer laser processing of ZnO thin films prepared by the sol-gel process

    International Nuclear Information System (INIS)

    Winfield, R.J.; Koh, L.H.K.; O'Brien, Shane; Crean, Gabriel M.


    ZnO thin films were prepared on soda-lime glass from a single spin-coating deposition of a sol-gel prepared with anhydrous zinc acetate [Zn(C 2 H 3 O 2 ) 2 ], monoethanolamine [H 2 NC 2 H 4 OH] and isopropanol. The deposited films were dried at 50 and 300 deg. C. X-ray analysis showed that the films were amorphous. Laser annealing was performed using an excimer laser. The laser pulse repetition rate was 25 Hz with a pulse energy of 5.9 mJ, giving a fluence of 225 mJ cm -2 on the ZnO film. Typically, five laser pulses per unit area of the film were used. After laser processing, the hexagonal wurtzite phase of zinc oxide was observed from X-ray diffraction pattern analysis. The thin films had a transparency of greater than 70% in the visible region. The optical band-gap energy was 3.454 eV. Scanning electron microscopy and profilometry analysis highlighted the change in morphology that occurred as a result of laser processing. This comparative study shows that our sol-gel processing route differs significantly from ZnO sol-gel films prepared by conventional furnace annealing which requires temperatures above 450 deg. C for the formation of crystalline ZnO

  4. Uptake behavior of titanium molybdophosphate for cesium and strontium

    International Nuclear Information System (INIS)

    Yavari, R.; Ahmadi, S.J.; Huang, Y.D.


    This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 deg C using column packed with H 3 O + form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH 4 Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution. (author)

  5. Clay mineralogy and geochemistry of the soils derived from metamorphic and mafic igneous parent rocks in Lahijan area

    International Nuclear Information System (INIS)

    Ramezanpour, H.; Hesami, R.; Zanjanchi, M. A.


    The mineralogical and geochemical composition of the soils of three representative pedons formed on basaltic andesite, andesitic basalt and phyllite were investigated. Results by x-ray diffraction showed that progressive weathering of rocks have been marked by gradual accumulation of Al, Fe, Ti, Mg, H 3 O + and depletion of Na, K, Ca and Si in the soil; although, predominant clay, loss and gain trend of elements was different on the various rocks. Based on x-ray diffraction analysis, minerals in basaltic andesite and andesitic basalt were similar but, the intensity of mica to smectite or vermiculite transformation for latter was relatively higher than the former. This process revealed the degradation mineral because of two reasons: (i) - smectite and vermiculite increased whereas mica decreased in surface horizons. (i i)-Irregular mixed layer of mica-smectite or vermiculite was present in deeper part (170 cm) of the soils from andesitic basalt but shallower depth (75 em) of the soils from basaltic andesite. Clay minerals in phyllite were mica and chlorite that stratified with vermiculite. However, the absence of smectite in phyllite might be attributed to more acidic condition or position of the Fe ion in the mineral lattice of chlorite (higher Fe in the interlayer hydroxide sheet)

  6. Study of the thermoluminescence emission of a natural α-cristobalite

    International Nuclear Information System (INIS)

    Correcher, V.; Sanchez M, L.; Garcia G, J.; Bustillo, M.A.; Garcia, R.


    Full text: The thermoluminescence properties of a well-characterised natural cristobalite from Lanzarote (Canary Islands, Spain) have been studied. The natural blue emission (at 400 nm) of this silica polymorph of quartz, reveals the appearance of three groups of components appearing at 150, 230-240 and 370 C that could be associated, respectively, with (i) structural defects (similar to quartz), (ii) the reversible phase transition that converts α-cristobalite into , β cristobalite and (iii) electron recombination with unstable holes trapped at oxygen vacancies next to Al ions linked to the formation of β-cristobalite. The dose dependence of the induced TL (ITL emission of β-irradiated samples at room temperature exhibits a linear increase in the glow intensity of the whole curve with increasing the dose (r 2 = 0.999) in the range 0.5-10 Gy. Similar than quartz, the ITL glow curves display four maxim peaked at 90, 110, 180 and 220 C that could be respectively linked to (i) oxygen vacancies, (ii) recombination of electrons with (H 3 O 4 ) 0 centres that can act as hole traps, (iii) [GeO 4 ] - centres that are stabilised with monovalent cations (H + , Li + or Na + ) and (iv) [AlO 4 ] 0 hole-like centres which-are created when alkali ions are moving away from Al sites related also probably to the aforementioned reversible phase transition. (Author)

  7. Study of the thermoluminescence emission of a natural α-cristobalite (United States)

    Correcher, V.; Garcia-Guinea, J.; Bustillo, M. A.; Garcia, R.

    The thermoluminescence (TL) properties of a well-characterised natural α-cristobalite from Lanzarote (Canary Islands, Spain) have been studied. The natural blue emission (at 400 nm) of this silica polymorph of quartz reveals the appearance of three groups of components peaked at 150, 230-240 and 370 °C, which could be associated, respectively, with (i) structural defects (similar to quartz), (ii) the reversible phase transition from α-cristobalite to β-cristobalite and (iii) electron recombination with unstable holes trapped at oxygen vacancies next to Al ions linked to the formation of β-cristobalite. Similar to quartz, the induced TL (ITL) glow curves display four maxima, peaked at 90, 110, 180 and 220 °C, which could be respectively associated with (i) oxygen vacancies, (ii) recombination of electrons with (H3O4)° centres that can act as hole traps, (iii) [GeO4]- centres that are stabilised with monovalent cations (H+, Li+ or Na+) and (iv) [AlO4]° hole-like centres that are created when alkali ions are moving away from Al sites related probably to the reversible phase transition. The dose dependence of the ITL emission of β-irradiated samples at room temperature exhibits a linear increase in the glow intensity of the 180 °C maximum when increasing the dose (r=0.997) in the range 0.5-10 Gy.

  8. Effect of heavy water on isolated rat liver mitochondria

    International Nuclear Information System (INIS)

    Huebner, G.


    The rate of O 2 consumption by isolated rat liver mitochondria was determined polarographically with a Clark electrode at 25 0 C in the active (state 3), strongly coupled (state 4) and decoupled state of the mitochondria in media containing H 2 16 O, D 2 16 O or H 2 18 O. The results confirm the value of the D 2 O isotope effect in the form on an O 2 -consumption inhibition. In H 2 18 O no isotope effect has been detected in the state of controlled respiration. In contrast, a strongly marked inverse isotope effect has been found in the active state after ADP addition and in the decoupled state after DNP addition. This inverse isotope effect occurs in reactions involving a preceding equilibrium. According to the chemiosmotic hypothesis of oxidative phosphorylation the formation of hydronium ions is part of this reaction. The equilibrium constant k 2 = 0.9774 for the hydronium ion in H 2 16 O and H 2 18 O implies that the formation of the hydronium ion in H 2 18 O is preferred to that in H 2 16 O. The high inverse H 2 18 O isotope effect respiration shows that the formation of H 3 O + contributes to the vectorial proton transport, probably as a preceding equilibrium, and that in the active state of the respiratory chain this reaction may be the rate-determining step. (author)

  9. Nanodispersed Suspensions of Zeolite Catalysts for Converting Dimethyl Ether into Olefins (United States)

    Kolesnichenko, N. V.; Yashina, O. V.; Ezhova, N. N.; Bondarenko, G. N.; Khadzhiev, S. N.


    Nanodispersed suspensions that are effective in DME conversion and stable in the reaction zone in a three-phase system (slurry reactor) are obtained from MFI zeolite commercial samples (TsVM, IK-17-1, and CBV) in liquid media via ultrasonic treatment (UST). It is found that the dispersion medium, in which ultrasound affects zeolite commercial sample, has a large influence on particle size in the suspension. UST in the aqueous medium produces zeolite nanoparticles smaller than 50 nm, while larger particles of MFI zeolite samples form in silicone or hydrocarbon oils. Spectral and adsorption data show that when zeolites undergo UST in an aqueous medium, the acid sites are redistributed on the zeolite surface and the specific surface area of the mesopores increases. Preliminary UST in aqueous media of zeolite commercial samples (TsVM, IK-17-1, and CBV) affects the catalytic properties of MFI zeolite nanodispersed suspensions. The selectivity of samples when paraffins and olefins form is largely due to superacid sites consisting of OH groups of hydroxonium ion H3O+.

  10. Photophysics of tryptophan in H2O, D2O, and in nonaqueous solvents

    International Nuclear Information System (INIS)

    Gudgin, E.; Lopez-Delgado, R.; Ware, W.R.


    The fluorescence properties of tryptophan in water and deuterated water have been examined. Tryptophan molecules exhibit three distinct fluorescence lifetimes in water which become longer in deuterated water; the two shorter lifetimes are present below the pK of the amino group and the long lifetime appears as the pH is raised through this pK. The steady-state quenching of tryptophan fluorescence by hydrogen ion in the region of pH less than 3 shows a definite wavelength effect, consistent with less-pronounced quenching of the subnanosecond component whose emission maximum is at 330 nm. The Stern-Volmer plots show a marked curvature in the direction of decreasing Stern-Volmer constant as [H 3 O + ] increases. Deuterium ion also quenches tryptophan fluorescence at low pD. A kinetic scheme is proposed which reproduces both the steady-state and lifetime quenching results. Tryptophan in methanol or ethanol exhibits three fluorescence lifetimes; the relative percentage of the long component vs. the intermediate component can be varied by the addition of triethylamine or acid. In dimethyl sulfoxide, tryptophan and tryptophan deuterated at the amino and ring nirogen positions show identical behavior, both having the same decay parameters. These results are discussed in light of the theories which have recently been proposed to account for the several components in tryptophan fluorescence decay. Solvent interaction is suggested to play a critical role

  11. Topotactic transformations of sodalite cages: synthesis and NMR study of mixed salt-free and salt-bearing sodalites. (United States)

    Trill, Henning; Eckert, Hellmut; Srdanov, Vojislav I


    A series of mixed sodalite samples, Na(8)[Al(6)Si(6)O(24)]Br(x).(H(3)O(2))(2-x), with the unit cell stoichiometries varying in the 0 < x <2 region, was made by hydrothermal synthesis and subsequently transformed into Na(6+x)[Al(6)Si(6)O(24)]Br(x).(4H(2)O)(2-x) and Na(6+x)[Al(6)Si(6)O(24)]Br(x).circle(2-x) sodalites. Here, circle refers to an empty sodalite cage. The three series, referred hereafter to as the Br/basic, Br/hydro, and Br/dry series, were characterized by powder diffraction X-ray and by (23)Na, (27)Al, and (81)Br magic angle spinning (MAS) NMR and high-resolution triple quantum (TQ) MAS NMR spectroscopy. We determined that incorporation of Br(-) anions is 130 times more preferred than incorporation of H(3)O(2)(-) anions during the formation of sodalite cages, which permitted precise control of the halide content in the solid. Monotonic trends in chemical shifts were observed as a function of cage occupancy, reflecting continuous changes in structural parameters. A linear correlation between (81)Br chemical shift and lattice constant with a slope of -86 ppm/A was observed for all three series. Likewise, (23)Na chemical shifts for Na(+) cations in salt-bearing sodalite cages correlate linearly with the lattice constant. Both results indicate a universal dependence of the (23)Na and (81)Br chemical shifts on the Na-Br distance. The (27)Al chemical shifts of Br/basic and Br/hydro sodalites obey an established relation between delta(cs) and the average T-O-T bond angle of 0.72 ppm/degrees. Br/dry sodalites show two aluminum resonances, characterized by significantly different chemical shifts and quadrupolar interaction parameters. In that series, local symmetry distortions are evident from strong quadrupolar perturbations in the NMR spectra. P(Q) values for (27)Al vary between 0.8 MHz in Br/basic sodalites and 4.4 MHz in the Br/dry series caused by deviations from the tetrahedral symmetry of the salt-free sodalite cages. For (23)Na, P(Q) values of 0.8, 0

  12. Structures, equilibria and ligand exchange dynamics in the binary and ternary dioxouranium(VI)-ethylenediamine-N-N'-diacetic acid - fluoride system; a potentiometric, NMR and X-ray study

    International Nuclear Information System (INIS)

    Palladino, G.; Szabo, Z.; Fischer, A.; Grenthe, I.


    Full text of publication follows: The structure, thermodynamics and kinetics of the binary and ternary Uranyl(VI)- ethylenediamine- N-N'-di-acetate (in the following denoted EDDA) fluoride system have been studied using potentiometry, 1 H, 19 F NMR and a single-crystal X-ray determination. The potentiometric data were obtained using measurements of the free hydrogen ion and fluoride concentrations with glass and fluoride electrodes, respectively. The experimental data were used to deduce stoichiometry and equilibrium constants using a least square refinements programme. The UO 2 2+ - EDDA system could be studied up to -log[H 3 O + ] 3.4, after which a precipitate was formed. The test solutions contained two binary complexes, the uncharged UO 2 (EDDA)(aq) and UO 2 (H 3 EDDA) 3+ , with equilibrium constants log β(UO 2 EDDA) = 11.63 ± 0.02 and log β(UO 2 H 3 EDDA 3+ ) = 1.77 ± 0.04, respectively. By using fluoride as additional ligand the solubility increases because of the formation of very stable ternary complexes that allowed an experimental study over a larger pH range. The structure of the complexes in the ternary system was deduced using a combination of 1 H and 19 F NMR spectroscopy. The 19 F NMR spectra at lower pH, had peaks from the binary fluoride complexes (UO 2 F + , UO 2 F 2 (aq) and UO 2 F 3 - ) that could be used to obtain information on the equilibrium constants in the ternary system; at -log[H 3 O + ] > 4.7 new signals for the complexes (UO 2 ) 2 (EDDA) 2 F 2 2- , and UO 2 (EDDA)F - were observed. The analyses of 1 H NMR spectra indicate clearly that the EDDA ligand is chelate bonded in UO 2 (EDDA)F-. The fluorine exchange between UO 2 (EDDA)F- and UO 2 F 3 - was studied using 19 F NMR line-broadening technique. The experimental rate constant is k obs = k 0 + k 1 [UO 2 F 3 - ], with k 0 (3.24 ± 0.06) 10 2 s -1 and k 1 = (71.2 ± 2.3) 10 3 M -1 s -1 .The rate and the activation parameters for the exchange between UO 2 (EDDA)F - complex and free

  13. Ion and electron swarm studies of relevance to plasma processing: positive ion-molecule and electron-molecule studies of SF6 and derivatives

    International Nuclear Information System (INIS)

    Atterbury, C.; Kennedy, R.A.; Critchley, A.D.J.; Mayhew, C.A.


    Many sequential and parallel chemical reactions involving charged species occur in a plasma. Data needed to model plasma's chemical and physical environment includes cross-section, rate coefficients, and product ion distribution of electron-molecule and ion-molecule processes. Such reactions are studied by our group away from the complexity of the plasma environment, with experimental techniques that allow us to concentrate on a single process, where usually only one or two species are involved. A molecule commonly used in plasma etching applications is SF 6 1,2 . We have performed a series of positive ion-molecule and electron attachment studies on SF 6 and related molecules, including SeF 6 , TeF 6 (i.e. XF 6 molecules), SF 5 CF 3 and SF 5 Cl (i.e. SF 5 X molecules) 3- (. The studies of ion reactions with and electron attachment to SF 6 and physically similar molecules are of value when seeking to understand the ion and electron chemistry occurring in SF 6 containing plasma. The result of these studies are presented in this poster. Ion-molecule reactions. Rate coefficients and ion product branching ratios have been determined with the Selected Ion Flow Tube (SIFT) at room temperature (300 K) for reactions of SF 5 X with the following twenty-two cations; Ne + , F + , Ar + , N 2 + , N + , CO + , CO 2 + , O + , N 2 O + , O 2 + , SF 4 + , CF 2 + , SF + , SF 2 + , NO 2 + , SF 5 + , NO + , CF + , CF 3 + , SF 3 + , and H 3 O + (listed in order of decreasing recombination energy). SF 2 + , NO 2 + , NO + , SF 3 + , and H 3 O + are found to be unreacted with both SF 5 CF 3 and SF 5 Cl. The majority of the other reactions proceed with rate coefficients that are close to the capture value. Those found to occur at rates significantly less than the capture mechanism value re the reactions of O 2 + , SF + , SF 5 + , and CF 3 + with SF 5 CF 3 , and SF 4 + and SF 5 + with SF 5 Cl. Several distinction processes are observed among the large number of reactions studied, including

  14. Proton Transfers at the Air-Water Interface (United States)

    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 (applied quantum mechanics and molecular dynamics to simulate our experiments toward gaining insight at the

  15. Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C7H in Molecular Clouds (United States)

    Araki, Mitsunori; Takano, Shuro; Sakai, Nami; Yamamoto, Satoshi; Oyama, Takahiro; Kuze, Nobuhiko; Tsukiyama, Koichi


    Long carbon-chain molecules were searched for toward the low-mass star-forming region L1527, which is a prototypical source of warm carbon-chain chemistry (WCCC), using the 100 m Green Bank Telescope. Long carbon-chain molecules, C7H (2Π1/2), C6H (2Π3/2 and 2Π1/2), CH3C4H, and C6H2 (cumulene carbene, CCCCCCH2), and cyclic species of C3H and C3H2O were detected. In particular, C7H was detected for the first time in molecular clouds. The column density of C7H is determined to be 6 × 1010 cm-2. The column densities of the carbon-chain molecules including CH3C4H and C6H in L1527 relative to those in the starless dark cloud Taurus Molecular Cloud-1 Cyanopolyyne Peak (TMC-1 CP) tend to be systematically lower for long carbon-chain lengths. However, the column densities of C7H and C6H2 do not follow this trend and are found to be relatively abundant in L1527. This result implies that these long carbon-chain molecules are remnants of the cold starless phase. The results—that both the remnants and WCCC products are observed toward L1527—are consistent with the suggestion that the protostar can also be born in the parent core at a relatively early stage in the chemical evolution.

  16. Ligand design for alkali-metal-templated self-assembly of unique high-nuclearity CuII aggregates with diverse coordination cage units: crystal structures and properties. (United States)

    Du, Miao; Bu, Xian-He; Guo, Ya-Mei; Ribas, Joan


    The construction of two unique, high-nuclearity Cu(II) supramolecular aggregates with tetrahedral or octahedral cage units, [(mu(3)-Cl)[Li subset Cu(4)(mu-L(1))(3)](3)](ClO(4))(8)(H(2)O)(4.5) (1) and [[Na(2) subset Cu(12)(mu-L(2))(8)(mu-Cl)(4)](ClO(4))(8)(H(2)O)(10)(H(3)O(+))(2)](infinity) (2) by alkali-metal-templated (Li(+) or Na(+)) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N'-bis(3-propionyloxy)-1,4-diazacycloheptane (H(2)L(1)) or 1,5-diazacyclooctane-N,N'-diacetate acid (H(2)L(2)). Complex 1 crystallizes in the trigonal R3c space group (a = b = 20.866(3), c = 126.26(4) A and Z = 12), and 2 in the triclinic P1 space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) A, alpha = 99.836(6), beta = 95.793(5), gamma = 116.124(5) degrees and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu(4) tetrahedral cage units with a Li(+) template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu(6) polyhedra with a Na(+) template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.

  17. Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event (United States)

    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.

  18. Non-methane organic gas emissions from biomass burning: identification, quantification, and emission factors from PTR-ToF during the FIREX 2016 laboratory experiment (United States)

    Koss, Abigail R.; Sekimoto, Kanako; Gilman, Jessica B.; Selimovic, Vanessa; Coggon, Matthew M.; Zarzana, Kyle J.; Yuan, Bin; Lerner, Brian M.; Brown, Steven S.; Jimenez, Jose L.; Krechmer, Jordan; Roberts, James M.; Warneke, Carsten; Yokelson, Robert J.; de Gouw, Joost


    Volatile and intermediate-volatility non-methane organic gases (NMOGs) released from biomass burning were measured during laboratory-simulated wildfires by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF). We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC) pre-separation with electron ionization, H3O+ chemical ionization, and NO+ chemical ionization, an extensive literature review, and time series correlation, providing higher certainty for ion identifications than has been previously available. Our interpretation of the PTR-ToF mass spectrum accounts for nearly 90 % of NMOG mass detected by PTR-ToF across all fuel types. The relative contributions of different NMOGs to individual exact ion masses are mostly similar across many fires and fuel types. The PTR-ToF measurements are compared to corresponding measurements from open-path Fourier transform infrared spectroscopy (OP-FTIR), broadband cavity-enhanced spectroscopy (ACES), and iodide ion chemical ionization mass spectrometry (I- CIMS) where possible. The majority of comparisons have slopes near 1 and values of the linear correlation coefficient, R2, of > 0.8, including compounds that are not frequently reported by PTR-MS such as ammonia, hydrogen cyanide (HCN), nitrous acid (HONO), and propene. The exceptions include methylglyoxal and compounds that are known to be difficult to measure with one or more of the deployed instruments. The fire-integrated emission ratios to CO and emission factors of NMOGs from 18 fuel types are provided. Finally, we provide an overview of the chemical characteristics of detected species. Non-aromatic oxygenated compounds are the most abundant. Furans and aromatics, while less abundant, comprise a large portion of the OH reactivity. The OH reactivity, its major contributors, and the volatility distribution of emissions can change considerably over the course of a fire.

  19. Synthesis, structure, and characterization of a new sandwich-type arsenotungstocerate, [As 2W 18Ce 3O 71(H 2O) 3] 12- (United States)

    Alizadeh, M. H.; Eshtiagh-Hosseini, H.; Khoshnavazi, R.


    The rational synthesis of the new sandwich-type arsenotungstocerate [As 2W 18Ce 3O 71(H 2O) 3] 12- is reported for the first time by reaction of the trivacant lacunary species A-α-[AsW 9O 34] 9- with appropriate Ce IV. The single crystal structure analysis was carried out on K 7(H 3O) 5[As 2W 18Ce 3O 71(H 2O) 3]·9H 2O; H 39As 2Ce 3K 7O 88W 18; ( 2) which crystallizes in triclinic system, space group P overline1 with a=11.615(5) Å, b=17.638(7) Å, c=19.448(8) Å, α=73.643(7)°, β=88.799(7)°, γ=88.078(7)° and Z=2. The anion consists on two lacunary A-α-[AsW 9O 34] 9- Keggin moieties linked via a (H 2OCeO) 3 belt leading to a sandwich-type structure. Each cerium atom adopts tri-capped trigonal-prismatic coordination achieved by two terminal oxygen of an edge shared paired of WO 6 octahedra to each A-α-AsW 9O 349- moiety and two oxygen from the belt and the cap by one μ 3-O (As, W 2) to each A-α-AsW 9O 349- moiety and one external water ligand. The Ce-O bond lengths average in CeO 6 group, Ce-O(As, W 2) and Ce-O(nW) are 2.300(9), 2.887(3) and 2.682(5) Å, respectively. The acid/base titration curve reveals that the anion has two different titrable protons.

  20. Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates. (United States)

    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.

  1. Selective measurements of isoprene and 2-methyl-3-buten-2-ol based on NO+ ionization mass spectrometry

    Directory of Open Access Journals (Sweden)

    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. Theoretical study of isomerization and decomposition of propenal

    International Nuclear Information System (INIS)

    Chin, Chih-Hao; Lee, Shih-Huang


    We investigated the dynamics of isomerization and multi-channel dissociation of propenal (CH 2 CHCHO), methyl ketene (CH 3 CHCO), hydroxyl propadiene (CH 2 CH 2 CHOH), and hydroxyl cyclopropene (cyclic-C 3 H 3 -OH) in the ground potential-energy surface using quantum-chemical calculations. Optimized structures and vibrational frequencies of molecular species were computed with method B3LYP/6-311G(d,p). Total energies of molecules at optimized structures were computed at the CCSD(T)/6-311+G(3df,2p) level of theory. We established the potential-energy surface for decomposition to CH 2 CHCO + H, CH 2 CH + HCO, CH 2 CH 2 /CH 3 CH + CO, CHCH/CH 2 C + H 2 CO, CHCCHO/CH 2 CCO + H 2 , CHCH + CO + H 2 , CH 3 + HCCO, CH 2 CCH + OH, and CH 2 CC/cyclic-C 3 H 2 + H 2 O. Microcanonical rate coefficients of various reactions of trans-propenal with internal energies 148 and 182 kcal mol -1 were calculated using Rice-Ramsperger-Kassel-Marcus and Variational transition state theories. Product branching ratios were derivable using numerical integration of kinetic master equations and the steady-state approximation. The concerted three-body dissociation of trans-propenal to fragments C 2 H 2 + CO + H 2 is the prevailing channel in present calculations. In contrast, C 3 H 3 O + H, C 2 H 3 + HCO and C 2 H 4 + CO were identified as major channels in the photolysis of trans-propenal. The discrepancy between calculations and experiments in product branching ratios indicates that the three major photodissociation channels occur mainly on an excited potential-energy surface whereas the other channels occur mainly on the ground potential-energy surface. This work provides profound insight in the mechanisms of isomerization and multichannel dissociation of the system C 3 H 4 O.

  3. Kinetics of electron-induced decomposition of CF2Cl2 coadsorbed with water (ice): A comparison with CCl4

    International Nuclear Information System (INIS)

    Faradzhev, N.S.; Perry, C.C.; Kusmierek, D.O.; Fairbrother, D.H.; Madey, T.E.


    The kinetics of decomposition and subsequent chemistry of adsorbed CF 2 Cl 2 , activated by low-energy electron irradiation, have been examined and compared with CCl 4 . These molecules have been adsorbed alone and coadsorbed with water ice films of different thicknesses on metal surfaces (Ru; Au) at low temperatures (25 K; 100 K). The studies have been performed with temperature programmed desorption (TPD), reflection absorption infrared spectroscopy (RAIRS), and x-ray photoelectron spectroscopy (XPS). TPD data reveal the efficient decomposition of both halocarbon molecules under electron bombardment, which proceeds via dissociative electron attachment (DEA) of low-energy secondary electrons. The rates of CF 2 Cl 2 and CCl 4 dissociation increase in an H 2 O (D 2 O) environment (2-3x), but the increase is smaller than that reported in recent literature. The highest initial cross sections for halocarbon decomposition coadsorbed with H 2 O, using 180 eV incident electrons, are measured (using TPD) to be 1.0±0.2x10 -15 cm 2 for CF 2 Cl 2 and 2.5±0.2x10 -15 cm 2 for CCl 4 . RAIRS and XPS studies confirm the decomposition of halocarbon molecules codeposited with water molecules, and provide insights into the irradiation products. Electron-induced generation of Cl - and F - anions in the halocarbon/water films and production of H 3 O + , CO 2 , and intermediate compounds COF 2 (for CF 2 Cl 2 ) and COCl 2 , C 2 Cl 4 (for CCl 4 ) under electron irradiation have been detected using XPS, TPD, and RAIRS. The products and the decomposition kinetics are similar to those observed in our recent experiments involving x-ray photons as the source of ionizing irradiation

  4. Experimental study of para- and ortho-H3+ recombination (United States)

    Plašil, R.; Varju, J.; Hejduk, M.; Dohnal, P.; Kotrík, T.; Glosík, J.


    Recombination of H3+ with electrons is a key process for many plasmatic environments. Recent experiments on storage ring devices used ion sources producing H3+ with enhanced populations of H3+ ions in the para nuclear spin configuration to shed light on the theoretically predicted faster recombination of para states. Although increased recombination rates were observed, no in situ characterization of recombining ions was performed. We present a state selective recombination study of para- and ortho-H3+ ions with electrons at 77 K in afterglow plasma in a He/Ar/H2 gas-mixture. Both spin configurations of H3+ have been observed in situ with a near infrared cavity ring down spectrometer (NIR-CRDS) using the two lowest energy levels of H3+. Using hydrogen with an enhanced population of H2 molecules in para states allowed us to influence the [para-H3+]/[ortho-H3+] ratio in the discharge and in the afterglow. We observed an increase in the measured effective recombination rate coefficients with the increase of the fraction of para-H3+. Measurements with different fractions of para-H3+ at otherwise identical conditions allowed us to determine the binary recombination rate coefficients for pure para-H3+ pαbin(77 K) = (2.0±0.4)×10-7 cm3s-1 and pure ortho-H3+ oαbin(77 K) = (4±3)×10-8 cm3s-1.

  5. Modeling ion sensing in molecular electronics

    International Nuclear Information System (INIS)

    Chen, Caroline J.; Smeu, Manuel; Ratner, Mark A.


    We examine the ability of molecules to sense ions by measuring the change in molecular conductance in the presence of such charged species. The detection of protons (H + ), alkali metal cations (M + ), calcium ions (Ca 2+ ), and hydronium ions (H 3 O + ) is considered. Density functional theory (DFT) is used within the Keldysh non-equilibrium Green's function framework (NEGF) to model electron transport properties of quinolinedithiol (QDT, C 9 H 7 NS 2 ), bridging Al electrodes. The geometry of the transport region is relaxed with DFT. The transport properties of the device are modeled with NEGF-DFT to determine if this device can distinguish among the M + + QDT species containing monovalent cations, where M + = H + , Li + , Na + , or K + . Because of the asymmetry of QDT in between the two electrodes, both positive and negative biases are considered. The electron transmission function and conductance properties are simulated for electrode biases in the range from −0.5 V to 0.5 V at increments of 0.1 V. Scattering state analysis is used to determine the molecular orbitals that are the main contributors to the peaks in the transmission function near the Fermi level of the electrodes, and current-voltage relationships are obtained. The results show that QDT can be used as a proton detector by measuring transport through it and can conceivably act as a pH sensor in solutions. In addition, QDT may be able to distinguish among different monovalent species. This work suggests an approach to design modern molecular electronic conductance sensors with high sensitivity and specificity using well-established quantum chemistry

  6. Effect of water α radiolysis on the spent nuclear fuel UO2 matrix alteration

    International Nuclear Information System (INIS)

    Lucchini, J.F.


    In the option of long term storage or direct disposal of nuclear spent fuel, it is essential to study the long-term behaviour of the spent fuel matrix (UO 2 ) in water, in presence of ionizing radiations. This work gives some knowledge elements about the impact of aerated water alpha radiolysis on UO 2 alteration. An original experiment method was used in this study. UO 2 /water interfaces were irradiated by an external He 2+ ions beam. The sequential batch dissolution tests on UO 2 samples were performed in aerated deionized water, before, during and after a-irradiation under high fluxes. A corrosion product, identified as hydrated uranium peroxide, was formed on the UO 2 surface. The uranium release was 3 to 4 orders of magnitude higher under irradiation than out of irradiation. The concentrations of the radiolysis products H 2 O 2 and H 3 O + were affected by the uranium oxide surface. They could not only explain the whole uranium release reached during irradiation in water. Leaching experiments on UO X spent fuel samples (with or without the Zircaloy clad) were also performed, in hot cells. The uranium release was relatively small, and H 2 O 2 was not detected in solution. The rates of uranium release in aerated water during one hour were calculated. They were about mg -1 .m -2 .d -1 for spent fuel and for UO 2 , and about g -1 .m -2 .d -1 for UO 2 irradiated by He 2+ ions. The comparison of the results between the two kinds of experiment shows a difference of the behaviour in water between UO 2 irradiated by He 2+ ions and spent fuel. Some hypothesis are given to explain this difference. (author)

  7. Analysis of Marine Aerosol Polysaccharides by Pyrolysis Time-of-Flight Mass Spectrometry (United States)

    Lawler, M. J.; Grieman, M. M.; Sengur, I.; Saltzman, E. S.


    The relationship between surface ocean biological productivity and marine cloud formation and properties has been explored for decades, but the impacts of marine biogenic emissions on cloudiness and climate remain highly uncertain. This is in part due to the challenge of directly linking biogenic materials in the surface ocean with cloud-forming aerosol. It has been shown that polysaccharide gel-forming materials, also known as transparent exopolymers, may be mechanically ejected from the sea surface during air bubble bursting (Leck and Bigg, 2005). Existing analysis methods for such aerosols require considerable sample mass and sample preparation. As part of the multi-year seasonal North Atlantic Aerosols and Marine Ecosystems Study (NAAMES), ambient submicron marine aerosol was collected in November 2015 and May 2016 from the R/V Atlantis at using a Particle into Liquid Sampler (PILS). These samples of roughly 15 minute time resolution were frozen and returned to UC Irvine for analysis. A new technique has been developed to attempt to quantify polysaccharide material in these ambient samples. A small subsample (1- 5 µL) is taken from the PILS vial samples and allowed to dry on a Pt ribbon filament in the chemical ionization source region of a time-of-flight mass spectrometer. The sample then undergoes a two-step heating process, in which volatilizable molecules are first desorbed and then non-volatilizable large molecules such as polysaccharides are pyrolyzed. These desorbed molecules and decomposition products are ionized using either O2- or H3O+ reagent ion and are directly sampled into the mass spectrometer. The resulting spectra can then be compared to standards of known polysaccharide materials for quantification and potentially structural and/or compositional information.

  8. The mechanism for the primary biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Byakov, Vsevolod M; Stepanov, Sergei V


    The primary biological response of living organisms to the passage of fast charged particles is traditionally believed to be dominated by the chemical reactions of the radical products from the radiolysis of cellular water (OH, H, e aq - , O 2 - , H 2 O 2 ) and by the bioradicals that they produce (and which can also result from the direct electronic activation of biomolecules). This understanding has provided insight into how ionizing radiations affect biological systems and, most importantly, what radioprotection and radiosensibilizing effects are produced by chemical compounds introduced into an organism. However, a number of key radiobiological facts remain unexplained by the current theory, stimulating a search for other biologically active factors that may be triggered by radiation. This review examines a fact that is usually ignored in discussing the biological impact of ionizing radiation: the local increase in acidity in the water solution along the track of a charged particle. The acidity in the track is very different from its value for cellular water in a living organism. Biological processes are well-known to be highly sensitive to changes in the environmental acidity. It seems that the biological impact of ionizing radiations is dominated not by the water radiolysis products (mostly radicals) listed above but particles of a different nature, hydroxonium ions H 3 O + , where the term hydroxonium refer to protonated water molecules. This modification of the mechanism of primary radiobiological effects is in good agreement with experimental data. In particular, the extremal dependence of the relative biological efficiency (RBE) of radiations on their ionizing energy losses is accounted for in quantitative terms, as is the increase in the RBE in the relativistic energy range. (reviews of topical problems)

  9. Emissions of volatile organic compounds (VOCs) from oil and natural gas activities: compositional comparison of 13 major shale basins via NOAA airborne measurements (United States)

    Gilman, J.; Lerner, B. M.; Aikin, K. C.; De Gouw, J. A.; Koss, A.; Yuan, B.; Warneke, C.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Graus, M.; Tokarek, T. W.; Isaacman-VanWertz, G. A.; Sueper, D.; Worsnop, D. R.


    The recent and unprecedented increase in natural gas production from shale formations is associated with a rise in the production of non-methane volatile organic compounds (VOCs) including natural gas plant liquids (e.g., ethane, propane, and butanes) and liquid lease condensate (e.g., pentanes, hexanes, aromatics and cycloalkanes). Since 2010, the production of natural gas liquids and the amount of natural gas vented/flared has increased by factors of ~1.28 and 1.57, respectively (U.S. Energy and Information Administration), indicating an increasingly large potential source of hydrocarbons to the atmosphere. Emission of VOCs may affect local and regional air quality due to the potential to form tropospheric ozone and organic particles as well as from the release of toxic species such as benzene and toluene. The 2015 Shale Oil and Natural Gas Nexus (SONGNex) campaign studied emissions from oil and natural gas activities across the central United States in order to better understand their potential air quality and climate impacts. Here we present VOC measurements from 19 research flights aboard the NOAA WP-3D over 11 shale basins across 8 states. Non-methane hydrocarbons were measured using an improved whole air sampler (iWAS) with post-flight analysis via a custom-built gas chromatograph-mass spectrometer (GC-MS). The whole air samples are complimented by higher-time resolution measurements of methane (Picarro spectrometer), ethane (Aerodyne spectrometer), and VOCs (H3O+ chemical ionization mass spectrometer). Preliminary analysis show that the Permian Basin on the New Mexico/Texas border had the highest observed VOC mixing ratios for all basins studied. We will utilize VOC enhancement ratios to compare the composition of methane and VOC emissions for each basin and the associated reactivities of these gases with the hydroxyl radical, OH, as a proxy for potential ozone formation.

  10. Biomass pyrolysis: Thermal decomposition mechanisms of furfural and benzaldehyde (United States)

    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.

  11. Quantum chemical protocols for modeling reactions and spectra in astrophysical ice analogs: the challenging case of the C⁺ + H₂O reaction in icy grain mantles. (United States)

    Woon, David E


    Icy grain mantles that accrete on refractory dust particles in the very cold interstellar medium or beyond the snow line in protoplanetary disks serve as minute incubators for heterogeneous chemistry. Ice mantle chemistry can differ significantly from the gas phase chemistry that occurs in these environments and is often richer. Modeling ices and their chemistry is a challenging task for quantum theoretical methods, but theory promises insight into these systems that is difficult to attain with experiments. Density functional theory (DFT) is predominately employed for modeling reactions in icy grain mantles due to its favorable scalability, but DFT has limitations that risk undercutting its reliability for this task. In this work, basic protocols are proposed for identifying the degree to which DFT methods are able to reproduce experimental or higher level theoretical results for the fundamental interactions upon which ice mantle chemistry depends, including both reactive interactions and non-reactive scaffolding interactions. The exemplar of this study is the reaction of C(+) with H2O, where substantial methodological differences are found in the prediction of gas phase relative energetics for stationary points (about 10 kcal mol(-1) for the C-O bond energy of the H2OC(+) intermediate), which in turn casts doubt about employing it to treat the C(+) + H2O reaction on an ice surface. However, careful explorations demonstrate that B3LYP with small correlation consistent basis sets performs in a sufficiently reliable manner to justify using it to identify plausible chemical pathways, where the dominant products were found to be neutral HOC and the CO(-) anion plus one and two H3O(+) cations, respectively. Predicted vibrational and electronic spectra are presented that would serve to verify or disconfirm the pathways; the latter were computed with time-dependent DFT. Conclusions are compared with those of a recent similar study by McBride and coworkers (J. Phys. Chem

  12. Prevention of Renal Injury After Induction of Ozone Tolerance in Rats Submitted to Warm Ischaemia

    Directory of Open Access Journals (Sweden)

    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. Production and correlation of reactive oxygen and nitrogen species in gas- and liquid-phase generated by helium plasma jets under different pulse widths (United States)

    Liu, Zhijie; Zhou, Chunxi; Liu, Dingxin; Xu, Dehui; Xia, Wenjie; Cui, Qingjie; Wang, Bingchuan; Kong, Michael G.


    In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is mainly attributed to accumulation of space charges that lead to weakening of the reduced electric field with an increase of PW from low to high. More important, it is found that the excited reactive species, the positive and negative ions from plasma jet, and the concentrations of NO2- and NO3- in deionized water exposed to plasma jet also display the first increasing and then decreasing change trend with increase of PW, while the concentration of H2O2 in water almost displays the linearly increasing trend. This mainly results from the formation of the H3O+ and HO2-, as well as their ion water clusters that can produce more OH radicals to be converted into H2O2, while the NO2- and NO3- in gas phase can transport into water and exist most stably in water. The water cluster formation at gas-liquid interface is an important key process that can affect the chemical nature and dose of aqueous RONS in water; this is beneficial for understanding how the RONS are formed in liquid-phase.

  14. Emissions of volatile organic compounds (VOCs) from concentrated animal feeding operations (CAFOs): chemical compositions and separation of sources (United States)

    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.

  15. Ambient analysis of trace compounds in gaseous media by SIFT-MS. (United States)

    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.

  16. Photochemistry of limonene secondary organic aerosol studied with chemical ionization mass spectrometry (United States)

    Pan, Xiang

    Limonene is one of the most abundant monoterpenes in the atmosphere. Limonene easily reacts with gas-phase oxidants in air such as NO3, ozone and OH. Secondary organic aerosol (SOA) is formed when low vapor pressure products condense into particles. Chemicals in SOA particles can undergo further reactions with oxidants and with solar radiation that significantly change SOA composition over the course of several days. The goal of this work was to characterize radiation induced reaction in SOA. To perform experiments, we have designed and constructed an Atmospheric Pressure Chemical Ionization Mass Spectrometer (APCIMS) coupled to a photochemical cell containing SOA samples. In APCIMS, (H2O)nH 3O+ clusters are generated in a 63Ni source and react with gaseous organic analytes. Most organic chemicals are not fragmented by the ionization process. We have focused our attention on limonene SOA prepared in two different ways. The first type of SOA is produced by oxidation of limonene by ozone; and the second type of SOA is formed by the NO3-induced oxidation of limonene. They model the SOA formed under daytime and nighttime conditions, respectively. Ozone initiated oxidation is the most important chemical sink for limonene both indoors, where it is used for cleaning purposes, and outdoors. Terpenes are primarily oxidized by reactions with NO3 at night time. We generated limonene SOA under different ozone and limonene concentrations. The resulting SOA samples were exposed to wavelength-tunable radiation in the UV-Visible range between 270 nm and 630 nm. The results show that the photodegradation rates strongly depend on radiation wavelengths. Gas phase photodegradation products such as acetone, formaldehyde, acetaldehyde, and acetic acid were shown to have different production rates for SOA formed in different concentration conditions. Even for SOA prepared under the lowest concentrations, the SOA photodegradation was efficient. The conclusion is that exposure of SOA to

  17. Luminescent lanthanide coordination polymers synthesized via in-situ hydrolysis of dimethyl-3,4-furandicarboxylate

    International Nuclear Information System (INIS)

    Greig, Natalie E.; Einkauf, Jeffrey D.; Clark, Jessica M.; Corcoran, Eric J.; Karram, Joseph P.; Kent, Charles A.; Eugene, Vadine E.; Chan, Benny C.; Lill, Daniel T. de


    Dimethyl-3,4-furandicarboxylate undergoes hydrolysis under hydrothermal conditions with lanthanide (Ln) ions to form two-dimensional coordination polymers, [Ln(C 6 H 2 O 5 )(C 6 H 3 O 5 )(H 2 O)] n (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The resulting materials exhibit luminescent properties with quantum yields and lifetimes for the Eu(III) and Tb(III) compounds of 1.1±0.3% and 0.387±0.0001 ms, and 3.3±0.8% and 0.769±0.006 ms, respectively. Energy values for the singlet and triplet states were determined for dimethyl-3,4-furandicarboxylate and 3,4-furandicarboxylic acid. Excited state dynamics and structural features are examined to explicate the reported quantum yields. A series of other FDC structures is briefly presented. - Graphical abstract: A new two-dimensional coordination polymer derived from the in-situ hydrolysis of a furan dimethyl ester with lanthanide(III) ions was obtained in order to study its photophysical behavior when constructed from trivalent Eu and Tb. Quantum yields, lifetime measurements, and singlet/triplet state energies values were obtained. The nature of the material's excited state dynamics is examined and correlated to its structure in order to explain the overall luminescent efficiency of the system. - Highlights: • A new lanthanide–furandicarboxylate coordination polymer is presented. • Eu and Tb compounds display luminescent properties, albeit with low quantum yields. • Photophysical behavior explained through the compound's triplet state and structure. • Nonradiative deactivation of luminescence through high-energy oscillators was noted. • Molecular modeling of the organic moiety was conducted

  18. Structure And Chemistry Of Ion Masses ≤ 40 Amu In The Inner Coma Of Comet HalleyStructure And Chemistry Of Ion Masses ≤ 40 Amu In The Inner Coma Of Comet Halley (United States)

    Haider, S. A.; Bhardwaj, A.

    In this paper, we have developed a chemical model to study the chemistry of 46 ions (CH5+, SH+, S+, H2S+, NH3OH+, CH3+, HCO+, H2CO+, C2H3+, C3H3+, H3CO+, H2CN+, H3S+, NH3+, CH3OH2+, CH3OH+, NH4+, H3O+, N+, NH+, NH2+, N2+, C2H+, C+, CH2+, CH+, C2N+, C3H+, C2H4+, C2H5+, CO+, O+, H+, C2+, HCN+, OH+, O2+, CHOH2+, HNO+, N2H+, H2O+, CH4+, C2H2+, (H2O)2+, H5O2+ and C3H+) corresponding to masses ≤ 40 amu in the inner coma of comet Halley. The ionization sources included in the model are solar EUV photon, photoelectron and auroral electron of solar wind origin. The production rates, loss rates and mass densities of these ions are calculated using Analytical Yield Spectrum approach and coupled continuity equation controlled by steady state photochemical model, which involves over 600 chemical reactions between ions, neutrals, photons and electrons in the coma. The calculated mass densities are compared with Giotto Ion Mass Spectrometer (IMS) and Neutral Mass Spectrometer (NMS) data at radial distances 1500 km, 3500 km and 6000 km. The nine major peaks at 12, 15, 19, 26, 28, 31, 33, 35, and 39 amu observed in IMS/NMS spectra are reproduced well by model calculation. ^

  19. Non-methane organic gas emissions from biomass burning: identification, quantification, and emission factors from PTR-ToF during the FIREX 2016 laboratory experiment

    Directory of Open Access Journals (Sweden)

    A. R. Koss


    Full Text Available Volatile and intermediate-volatility non-methane organic gases (NMOGs released from biomass burning were measured during laboratory-simulated wildfires by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF. We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC pre-separation with electron ionization, H3O+ chemical ionization, and NO+ chemical ionization, an extensive literature review, and time series correlation, providing higher certainty for ion identifications than has been previously available. Our interpretation of the PTR-ToF mass spectrum accounts for nearly 90 % of NMOG mass detected by PTR-ToF across all fuel types. The relative contributions of different NMOGs to individual exact ion masses are mostly similar across many fires and fuel types. The PTR-ToF measurements are compared to corresponding measurements from open-path Fourier transform infrared spectroscopy (OP-FTIR, broadband cavity-enhanced spectroscopy (ACES, and iodide ion chemical ionization mass spectrometry (I− CIMS where possible. The majority of comparisons have slopes near 1 and values of the linear correlation coefficient, R2, of  >  0.8, including compounds that are not frequently reported by PTR-MS such as ammonia, hydrogen cyanide (HCN, nitrous acid (HONO, and propene. The exceptions include methylglyoxal and compounds that are known to be difficult to measure with one or more of the deployed instruments. The fire-integrated emission ratios to CO and emission factors of NMOGs from 18 fuel types are provided. Finally, we provide an overview of the chemical characteristics of detected species. Non-aromatic oxygenated compounds are the most abundant. Furans and aromatics, while less abundant, comprise a large portion of the OH reactivity. The OH reactivity, its major contributors, and the volatility distribution of emissions can change considerably over the course of a fire.

  20. Sorption of Fe3+ , Co2+ , Ce3+ , Cs+ and Ba2+ in zeolite X

    International Nuclear Information System (INIS)

    Martinez M, V.


    The sorption behavior of Fe 3+ , Co 2+ , Ce 3+ , Cs + , and Ba 2+ in aqueous solutions, was studied in presence of zeolite X. Solutions of Fe(NO 3 ) 3 . 9 H 2 O, Co(NO 3 ) 2 . 6 H 2 O, Ce(NO 3 ) 3 . 6 H 2 O, Cs NO 3 and Ba(NO 3 ) 2 were labelled with the respectively radioactive isotopes Fe 59 , Co 60 , Cs 134 , Ba 139 and Ce 141 . 20 ml. of each solution was left in contact with 200 mg. of zeolite for different periods. Later the zeolites were separated by centrifugation from the aqueous solutions and the radioactivity of the aqueous phases was measured with a NaI(Tl) solid-state well detector coupled to a single-channel Picker analyzer or with a Gel hyper pure solid-state detector coupled to a 2048 channel pulse height analyzer. When Cs + in the aqueous solutions was left in contact with zeolite X it was found that it does not occupy all cationic sites in the zeolite due to the ionic radium effect. A similar behavior was found for the divalent ions. In all cases, when the pH was not controlled, the zeolite lost part of its crystallinity and when the divalent ions were exchanged again by Na + , the zeolite recovered completely its crystallinity. During the sorption, the ionic radius, and the charge are important parameters as well as the pH. When the pH of the solution was adjusted between 6.5 - 7.0 the crystallinity was maintained in some cases. For Fe 3+ the crystallinity after the ion exchange was 94 % and when the pH was not adjusted the crystallinity was completely lost. It was found as well that the zeolite X induces the formation of H 3 O + which competes with the cations for the sites in the zeolite. (Author)

  1. Widespread rotationally hot hydronium ion in the galactic interstellar medium

    International Nuclear Information System (INIS)

    Lis, D. C.; Phillips, T. G.; Schilke, P.; Comito, C.; Higgins, R.


    We present new Herschel 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 H 3 O + 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, this is unlikely in the largely quiescent environment of the Galactic disk clouds. We suggest instead that the highly excited states of the hydronium ion are populated mainly by exoergic chemical formation processes and the temperature describing the rotational level population does not represent the physical temperature of the medium. The same arguments may be applicable to other symmetric top rotors, such as ammonia. This offers a simple explanation of the long-standing puzzle of the presence of a pervasive, hot molecular gas component in the central region of the Milky Way. Moreover, our observations suggest that this is a universal process not limited to the active environments associated with galactic nuclei.

  2. A convenient method for calculation of ionic diffusion coefficients for accurate selected ion flow tube mass spectrometry, SIFT-MS (United States)

    Dryahina, K.; Spanel, P.


    A method to calculate diffusion coefficients of ions important for the selected ion flow tube mass spectrometry, SIFT-MS, is presented. The ions, on which this method is demonstrated, include the SIFT-MS precursors H3O+(H2O)0,1,2,3, NO.+(H2O)0,1,2 and O2+ and the product ions relevant to analysis of breath trace metabolites ammonia (NH3+(H2O)0,1,2, NH4+(H2O)0,1,2), acetaldehyde (C2H4OH+(H2O)0,1,2), acetone (CH3CO+, (CH3)2CO+, (CH3)2COH+(H2O)0,1, (CH3)2CO.NO+), ethanol (C2H5OHH+(H2O)0,1,2) and isoprene (C5H7+, C5H8+, C5H9+). Theoretical model of the (12, 4) potential for interaction between the ions and the helium atoms is used, with the repulsive part approximated by the mean hard-sphere cross section and the attractive part describing ion-induced dipole interactions. The reduced zero-field mobilities at 300 K are calculated using the Viehland and Mason theory [L.A. Viehland, S.L. Lin, E.A. Mason, At. Data Nucl. Data Tables, 60 (1995) 37-95], parameterised by a simple formula as a function of the mean hard-sphere cross section, and converted to diffusion coefficients using the Einstein relation. The method is tested on a set of experimental data for simple ions and cluster ions.

  3. Sugar Radical Formation by a Proton Coupled Hole Transfer in 2′-Deoxyguanosine Radical Cation (2′-dG•+): A Theoretical Treatment (United States)

    Kumar, Anil; Sevilla, Michael D.


    Previous experimental and theoretical work has established that electronic excitation of a guanine cation radical in nucleosides or in DNA itself leads to sugar radical formation by deprotonation from the dexoxyribose sugar. In this work we investigate a ground electronic state pathway for such sugar radical formation in a hydrated one electron oxidized 2′-deoxyguanosine (dG•+ + 7H2O), using density functional theory (DFT) with the B3LYP functional and the 6-31G* basis set. We follow the stretching of the C5′-H bond in dG•+ to gain an understanding of the energy requirements to transfer the hole from the base to sugar ring and then to deprotonate to proton acceptor sites in solution and on the guanine ring. The geometries of reactant (dG•+ + 7H2O), transition state (TS) for deprotonation of C5′ site and product (dG(•C5′, N7-H+) + 7 H2O) were fully optimized. The zero point energy (ZPE) corrected activation energy (TS) for the proton transfer (PT) from C5′ is calculated to be 9.0 kcal/mol and is achieved by stretching the C5′-H bond by 0.13 Å from its equilibrium bond distance (1.099 Å). Remarkably, this small bond stretch is sufficient to transfer the “hole” (positive charge and spin) from guanine to the C5′ site on the deoxyribose group. Beyond the TS, the proton (H+) spontaneously adds to water to form a hydronium ion (H3O+) as an intermediate. The proton subsequently transfers to the N7 site of the guanine (product). The 9 kcal/mol barrier suggests slow thermal conversion of the cation radical to the sugar radical but also suggests that localized vibrational excitations would be sufficient to induce rapid sugar radical formation in DNA base cation radicals. PMID:19754084

  4. Evaluation of B3LYP, X3LYP, and M06-Class Density Functionals for Predicting the Binding Energies of Neutral, Protonated, and Deprotonated Water Clusters. (United States)

    Bryantsev, Vyacheslav S; Diallo, Mamadou S; van Duin, Adri C T; Goddard, William A


    In this paper we assess the accuracy of the B3LYP, X3LYP, and newly developed M06-L, M06-2X, and M06 functionals to predict the binding energies of neutral and charged water clusters including (H2O)n, n = 2-8, 20), H3O(+)(H2O)n, n = 1-6, and OH(-)(H2O)n, n = 1-6. We also compare the predicted energies of two ion hydration and neutralization reactions on the basis of the calculated binding energies. In all cases, we use as benchmarks calculated binding energies of water clusters extrapolated to the complete basis set limit of the second-order Møller-Plesset perturbation theory with the effects of higher order correlation estimated at the coupled-cluster theory with single, double, and perturbative triple excitations in the aug-cc-pVDZ basis set. We rank the accuracy of the functionals on the basis of the mean unsigned error (MUE) between calculated benchmark and density functional theory energies. The corresponding MUE (kcal/mol) for each functional is listed in parentheses. We find that M06-L (0.73) and M06 (0.84) give the most accurate binding energies using very extended basis sets such as aug-cc-pV5Z. For more affordable basis sets, the best methods for predicting the binding energies of water clusters are M06-L/aug-cc-pVTZ (1.24), B3LYP/6-311++G(2d,2p) (1.29), and M06/aug-cc-PVTZ (1.33). M06-L/aug-cc-pVTZ also gives more accurate energies for the neutralization reactions (1.38), whereas B3LYP/6-311++G(2d,2p) gives more accurate energies for the ion hydration reactions (1.69).

  5. Novel pre-treatment of zeolite materials for the removal of sodium ions: potential materials for coal seam gas co-produced wastewater. (United States)

    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.

  6. Rechargeable Aluminum-Ion Batteries Based on an Open-Tunnel Framework. (United States)

    Kaveevivitchai, Watchareeya; Huq, Ashfia; Wang, Shaofei; Park, Min Je; Manthiram, Arumugam


    Rechargeable batteries based on an abundant metal such as aluminum with a three-electron transfer per atom are promising for large-scale electrochemical energy storage. Aluminum can be handled in air, thus offering superior safety, easy fabrication, and low cost. However, the development of Al-ion batteries has been challenging due to the difficulties in identifying suitable cathode materials. This study presents the use of a highly open framework Mo 2.5 +  y VO 9 +  z as a cathode for Al-ion batteries. The open-tunnel oxide allows a facile diffusion of the guest species and provides sufficient redox centers to help redistribute the charge within the local host lattice during the multivalent-ion insertion, thus leading to good rate capability with a specific capacity among the highest reported in the literature for Al-based batteries. This study also presents the use of Mo 2.5 +  y VO 9 +  z as a model host to develop a novel ultrafast technique for chemical insertion of Al ions into host structures. The microwave-assisted method employing diethylene glycol and aluminum diacetate (Al(OH)(C 2 H 3 O 2 ) 2 ) can be performed in air in as little as 30 min, which is far superior to the traditional chemical insertion techniques involving moisture-sensitive organometallic reagents. The Al-inserted Al x Mo 2.5 +  y VO 9 +  z obtained by the microwave-assisted chemical insertion can be used in Al-based rechargeable batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Composición química del agua de lluvia y de niebla recolectada en la reserva biológica Monteverde

    Directory of Open Access Journals (Sweden)

    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.

  8. Tracking the Chemical Transformations at the Brønsted Acid Site upon Water-Induced Deprotonation in a Zeolite Pore

    Energy Technology Data Exchange (ETDEWEB)

    Vjunov, Aleksei; Wang, Meng; Govind, Niranjan; Huthwelker, Thomas; Shi, Hui; Mei, Donghai; Fulton, John L.; Lercher, Johannes A.


    We report the structural changes induced by Brønsted acidic site deprotonation in a zeolite with MFI structure as a function of temperature up to 430°C using in situ Al K-edge X-ray absorption fine structure spectroscopy (XAFS). At ambient conditions, the protons are present as hydrated hydronium ions (H3O+(H2O)n) that are ion-paired to the anionic, Al tetrahedral (T) site. At elevated temperatures, loss of water molecules hydrating the hydronium ions leads to an unstable free hydronium ion that disso-ciates to form the hydroxylated T-site. The formation of this (-O3)-Al-(OH-) species leads to the elongation of one of the four Al-O bonds and causes significant distortion of the tetrahedral symmetry about the Al atom. This distortion leads to the appearance of new pre-edge features in the Al K-edge X-ray absorption near edge structure (XANES) spectra. The pre-edge peak assignment is confirmed by time-dependent density functional theory calculation of the XANES spectrum. The XANES spectra are also sensitive to solutes or solvent that are in proximity to the T-site. A second structural transition occurs at about the same temperature, namely the conversion of a minor fraction of extra-framework octahedral Al present in the sample at ambient conditions to a tetrahedral species through the de-coordination of H2O-ligands. Both IR spectroscopy and thermogravimetric analysis (TGA) are further used to confirm the overall chemical transformation of the T-site.

  9. Hydronium-Induced Switching between CO2 Electroreduction Pathways. (United States)

    Seifitokaldani, Ali; Gabardo, Christine M; Burdyny, Thomas; Dinh, Cao-Thang; Edwards, Jonathan P; Kibria, Md Golam; Bushuyev, Oleksandr S; Kelley, Shana O; Sinton, David; Sargent, Edward H


    Over a broad range of operating conditions, many CO 2 electroreduction catalysts can maintain selectivity toward certain reduction products, leading to materials and surfaces being categorized according to their products; here we ask, is product selectivity truly a property of the catalyst? Silver is among the best electrocatalysts for CO in aqueous electrolytes, where it reaches near-unity selectivity. We consider the hydrogenations of the oxygen and carbon atoms via the two proton-coupled-electron-transfer processes as chief determinants of product selectivity; and find using density functional theory (DFT) that the hydronium (H 3 O + ) intermediate plays a key role in the first oxygen hydrogenation step and lowers the activation energy barrier for CO formation. When this hydronium influence is removed, the activation energy barrier for oxygen hydrogenation increases significantly, and the barrier for carbon hydrogenation is reduced. These effects make the formate reaction pathway more favorable than CO. Experimentally, we then carry out CO 2 reduction in highly concentrated potassium hydroxide (KOH), limiting the hydronium concentration in the aqueous electrolyte. The product selectivity of a silver catalyst switches from entirely CO under neutral conditions to over 50% formate in the alkaline environment. The simulated and experimentally observed selectivity shift provides new insights into the role of hydronium on CO 2 electroreduction processes and the ability for electrolyte manipulation to directly influence transition state (TS) kinetics, altering favored CO 2 reaction pathways. We argue that selectivity should be considered less of an intrinsic catalyst property, and rather a combined product of the catalyst and reaction environment.

  10. FIREX (Fire Influence on Regional and Global Environments Experiment): Measurements of Nitrogen Containing Volatile Organic Compounds (United States)

    Warneke, C.; Schwarz, J. P.; Yokelson, R. J.; Roberts, J. M.; Koss, A.; Coggon, M.; Yuan, B.; Sekimoto, K.


    A combination of a warmer, drier climate with fire-control practices over the last century have produced a situation in which we can expect more frequent fires and fires of larger magnitude in the Western U.S. and Canada. There are urgent needs to better understand the impacts of wildfire and biomass burning (BB) on the atmosphere and climate system, and for policy-relevant science to aid in the process of managing fires. The FIREX (Fire Influence on Regional and Global Environment Experiment) research effort is a multi-year, multi-agency measurement campaign focused on the impact of BB on climate and air quality from western North American wild fires, where research takes place on scales ranging from the flame-front to the global atmosphere. FIREX includes methods development and small- and large-scale laboratory and field experiments. FIREX will include: emission factor measurements from typical North American fuels in the fire science laboratory in Missoula, Montana; mobile laboratory deployments; ground site measurements at sites influenced by BB from several western states. The main FIREX effort will be a large field study with multiple aircraft and mobile labs in the fire season of 2019. One of the main advances of FIREX is the availability of various new measurement techniques that allows for smoke evaluation in unprecedented detail. The first major effort of FIREX was the fire science laboratory measurements in October 2016, where a large number of previously understudied Nitrogen containing volatile organic compounds (NVOCs) were measured using H3O+CIMS and I-CIMS instruments. The contribution of NVOCs to the total reactive Nitrogen budget and the relationship to the Nitrogen content of the fuel are investigated.

  11. Water-lactose behavior as a function of concentration and presence of lactic acid in lactose model systems. (United States)

    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. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. [Mechanism of potassium channel in hypoxia-ischemic brain edema: experiment with neonatal rat astrocyte]. (United States)

    Fu, Xue-mei; Xiang, Long; Liao, Da-qing; Feng, Zhi-chun; Mu, De-zhi


    To investigate the mechanism of potassium channel in brain edema caused by hypoxia-ischemia (HI). Astrocytes were obtained from 3-day-old SD rats, cultured, and randomly divided into 2 groups: normoxia group, cultured under normoxic condition, and hypoxic-ischemic group, cultured under hypoxic-ischemic condition. The cell volume was measured by radiologic method. Patch-clamp technique was used to observe the electric physiological properties of the voltage-gated potassium channels (Kv) in a whole cell configuration, and the change of voltage-gated potassium channel current (IKv) was recorded in cultured neonatal rat astrocyte during HI. 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-methyl-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. 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 Pastrocytes significantly increased during HI and the degrees of edema mediated by AQP4 knockdown at different time points were all significantly milder (all Pastrocytes via aquaporin-4 and then cell swelling.

  13. A spherical electron cloud hopping model for studying product branching ratios of dissociative recombination. (United States)

    Yu, Hua-Gen


    A spherical electron cloud hopping (SECH) model is proposed to study the product branching ratios of dissociative recombination (DR) of polyatomic systems. In this model, the fast electron-captured process is treated as an instantaneous hopping of a cloud of uniform spherical fractional point charges onto a target M+q ion (or molecule). The sum of point charges (-1) simulates the incident electron. The sphere radius is determined by a critical distance (Rc eM) between the incoming electron (e-) and the target, at which the potential energy of the e(-)-M+q system is equal to that of the electron-captured molecule M+q(-1) in a symmetry-allowed electronic state with the same structure as M(+q). During the hopping procedure, the excess energies of electron association reaction are dispersed in the kinetic energies of M+q(-1) atoms to conserve total energy. The kinetic energies are adjusted by linearly adding atomic momenta in the direction of driving forces induced by the scattering electron. The nuclear dynamics of the resultant M+q(-1) molecule are studied by using a direct ab initio dynamics method on the adiabatic potential energy surface of M+q(-1), or together with extra adiabatic surface(s) of M+q(-1). For the latter case, the "fewest switches" surface hopping algorithm of Tully was adapted to deal with the nonadiabaticity in trajectory propagations. The SECH model has been applied to study the DR of both CH+ and H3O+(H2O)2. The theoretical results are consistent with the experiment. It was found that water molecules play an important role in determining the product branching ratios of the molecular cluster ion.

  14. SAXS measurements of crystallization in Me PEEK

    International Nuclear Information System (INIS)

    Barberato, C.; Kellerman, G.; Craievich, A.F.; Torriani, I.L.


    Full text. Preliminary small-angle x-ray scattering (SAXS) measurements on a variety of methyl-substituted poly(aryl ether ether ketone) (Me PEEK) samples have been performed at the D11AA-SAXS beam line of the Brazilian National Synchrotron Light Laboratory (LNLS).Me PEEK is an industrially important thermoplastic material exhibiting crystallization upon annealing at temperatures between 175 and 200 deg C. Differential Scanning Calorimetry (DSC) measurements (Handa Y.P., Roovers, J., Wang, F., Macromolecules 27(19), 551-5516 (1994)) indicate that the presence of supercritical fluids during thermal treatment can have dramatic effects on the melting behavior of Me PEEK when compared to similar data for materials annealed in air. These observations have been made for samples demonstrating no significant differences in the extent of crystallinity suggesting that it is the nature of the crystallites that is affected by the presence of additives during the thermal treatment. In this preliminary study, scattering profiles for three Me PEEK samples (as received, thermally treated in air and thermally treated with supercritical 0.85 CO 2 +C H 3 O H gas) are obtained. The data are analyzed to provide some measure of the variation in crystallite structure between the thermally treated samples. Scattering data obtained in the very small-angle region on the same samples at the High Brilliance Beamline (ID2/BM4) experiments performed by Olivier Diat and M.A. Singh, Dec. 11996) of the European Synchrotron Radiation Facility (ESRF) is combined with the Brazilian National Laboratory on Synchrotron Light (LNLS) data to provide information over 3 decades of scattering angle. This work is part of a larger study of the use of supercritical fluids to control the level and morphology of crystallization in these materials. (author)

  15. The Effect of Broadband Soft X-Rays in SO2-Containing Ices: Implications on the Photochemistry of Ices toward Young Stellar Objects (United States)

    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.

  16. Use of Proton-Transfer-Reaction Mass Spectrometry to Characterize Volatile Organic Compound Sources at the La Porte Super Site During the Texas Air Quality Study 2000

    Energy Technology Data Exchange (ETDEWEB)

    Karl, Thomas G.; Jobson, B Tom T.; Kuster, W. C.; Williams, Eric; Stutz, Jochen P.; Shetter, Rick; Hall, Samual R.; Goldan, P. D.; Fehsenfeld, Fred C.; Lindinger, Werner


    Proton-transfer-reaction mass spectrometry (PTR-MS) was deployed for continuous real-time monitoring of volatile organic compounds (VOCs) at a site near the Houston Ship Channel during the Texas Air Quality Study 2000. Overall, 28 ions dominated the PTR-MS mass spectra and were assigned as anthropogenic aromatics (e.g., benzene, toluene, xylenes) and hydrocarbons (propene, isoprene), oxygenated compounds (e.g., formaldehyde, acetaldehyde, acetone, methanol, C7 carbonyls), and three nitrogencontaining compounds (e.g., HCN, acetonitrile and acrylonitrile). Biogenic VOCs were minor components at this site. Propene was the most abundant lightweight hydrocarbon detected by this technique with concentrations up to 100+ nmol mol-1, and was highly correlated with its oxidation products, formaldehyde (up to ~40 nmol mol-1) and acetaldehyde (up to ~80 nmol/mol), with typical ratios close to 1 in propene-dominated plumes. In the case of aromatic species the high time resolution of the obtained data set helped in identifying different anthropogenic sources (e.g., industrial from urban emissions) and testing current emission inventories. A comparison with results from complimentary techniques (gas chromatography, differential optical absorption spectroscopy) was used to assess the selectivity of this on-line technique in a complex urban and industrial VOC matrix and give an interpretation of mass scans obtained by ‘‘soft’’ chemical ionization using proton-transfer via H3O+. The method was especially valuable in monitoring rapidly changing VOC plumes which passed over the site, and when coupled with meteorological data it was possible to identify likely sources.

  17. Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Copper-Based Metal-Organic Porous Materials for CO2 Electrocatalytic Reduction to Alcohols. (United States)

    Albo, Jonathan; Vallejo, Daniel; Beobide, Garikoitz; Castillo, Oscar; Castaño, Pedro; Irabien, Angel


    The electrocatalytic reduction of CO 2 has been investigated using four Cu-based metal-organic porous materials supported on gas diffusion electrodes, namely, (1) HKUST-1 metal-organic framework (MOF), [Cu 3 (μ 6 -C 9 H 3 O 6 ) 2 ] n ; (2) CuAdeAce MOF, [Cu 3 (μ 3 -C 5 H 4 N 5 ) 2 ] n ; (3) CuDTA mesoporous metal-organic aerogel (MOA), [Cu(μ-C 2 H 2 N 2 S 2 )] n ; and (4) CuZnDTA MOA, [Cu 0.6 Zn 0.4 (μ-C 2 H 2 N 2 S 2 )] n . The electrodes show relatively high surface areas, accessibilities, and exposure of the Cu catalytic centers as well as favorable electrocatalytic CO 2 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 CO 2 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.

  19. Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

    Directory of Open Access Journals (Sweden)

    A. Wonaschütz


    Full Text Available During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE, a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs: between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm−3, which lead to substantially increased cloud condensation nuclei (CCN concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C and water-soluble organic mass (WSOM increased with plume age: from −3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94. High-resolution aerosol mass spectrometer (AMS spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

  20. Thermodynamic stability of complexes of BF3, PF5 and AsF5 with chlorine fluorides, oxyfluorides, and related compounds

    International Nuclear Information System (INIS)

    Trowbridge, L.D.


    The recent discovery of solid, water sensitive, arsenic-containing deposits in auxiliary process piping in the PGDP led to a search for explanations that could account for such accumulated material. A plausible explanation for the deposits is the formation of complexes of AsF 5 with one or more gases that may have been present as a result of cascade equipment cleanup activities. A literature search was performed. The target of the search was literature that would provide information on the dissociation pressure of complexes of AsF 5 or its hydrolysis products with any gases that may be (at least intermittently) present in the cascade location where the deposits were found. While the precise information sought (namely reliable, accurate dissociation pressures of such complexes at cascade temperatures) was not found in the detail desired. other information on these or similar complexes was obtained which permits prediction of the conditions under which the complexes might form, dissociate, or migrate, and how they might behave in the presence of atmospheric moisture. Information was gathered on potential AsF 5 complexes with ClF, ClF 3 , ClF 5 , ClF 3 O, ClO 2 F, and ClO 3 F. Information was also collected on many other related complexes as it was encountered, particularly for series of complexes which could assist in predicting chemical trends. Thermodynamic analysis and property estimation methods have been used to generate provisional estimates of the dissociation pressures of the two complexes ClF 3 *AsF 5 and ClO 2 F*AsF 5 . In addition, several hydrolysis species have been identified, and stability properties of the most relevant such complex (H 3 O*AsF 6 ) have similarly been estimated. While the predicted dissociation pressures are somewhat uncertain. they do lead to a tentative picture of the formation and behavior of such complexes in a cascade cleanup environment

  1. Pickup Ions in the Plasma Environments of Mars, Comets, and Enceladus (United States)

    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.


    International Nuclear Information System (INIS)

    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 H 2 O:CO 2 :NH 3 :SO 2 (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 SO 2 -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 H 2 O 2 , H 3 O + , SO 3 , CO, and OCN − . The dissociation cross section of parental species was on the order of (2–7) × 10 −18 cm 2 . The ice temperature does not seem to affect the stability of SO 2 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. Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

    International Nuclear Information System (INIS)

    Pang Xuexia; Deng Zechao; Jia Pengying; Liang Weihua; Li Xia


    A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km). The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10 10 ∼ 10 14 cm −3 , the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O 2 − , O 4 − , CO 4 − and CO 3 − are the dominant negative species when the initial electron density n e0 ≤ 10 13 cm −3 , and only electrons and CO 3 − are left when n e0 ≥ 10 15 cm −3 · N + 2 , N + 4 and O + 2 are dominant in the positive charges for any ionization degree. Other positive species, such as O + 4 , N + 3 , NO + , NO + 2 , Ar + 2 and H 3 O + ·H 2 O, are dominant only for a certain ionization degree and in a certain period. (low temperature plasma)

  4. Construction of three metal-organic frameworks based on multifunctional T-shaped tripodal ligands, H3PyImDC

    KAUST Repository

    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.

  5. Electron Paramagnetic Resonance: Elementary Theory and Practical Applications, Second Edition (John A. Weil and James R. Bolton) (United States)

    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

  6. Fabrication of Al doped ZnO films using atmospheric pressure cold plasma

    International Nuclear Information System (INIS)

    Suzaki, Yoshifumi; Miyagawa, Hayato; Yamaguchi, Kenzo; Kim, Yoon-Kee


    Under atmospheric pressure, homogeneous non-equilibrium cold plasma was generated stably by high voltage pulsed power (1 kV, 20 kHz, 38 W) excitation of a mixture of He and O 2 gases produced by a dielectric barrier discharge setup. By feeding Bis (2 methoxy‐6-methyl‐3, 5-heptanedione) Zn (Zn-MOPD, C 18 H 3 O 6 Zn) and Tris (2-methoxy‐6‐methy l‐3, 5-heptanedione) Al (Al-MOPD, C 27 H 45 O 9 Al) into this plasma with He carrier gas, transparent flat Al-doped ZnO (ZnO:Al) films about 120–240 nm thick were prepared on glass substrates directly under the slit made into the cathode. Deposition rates of the films were about 20–40 nm/min. The concentration of Al was measured by inductively coupled plasma atomic emission spectroscopy. The composition ratio of Al to Zn was 7.8 mol% when the carrier He gas flow rate of Al-MOPD was 30 cm 3 . The average transmittance of all films was more than 85% in the wavelength range from 400 to 800 nm. When the composition ratio of Al/Zn was between 1.1 and 7.8 mol%, the optical band gap of the film increased from 3.28 to 3.40 eV. The resistivity of ZnO:Al film was 2.96 Ω cm at 1.3 mol% of Al/Zn. In addition, the microstructure of the films was studied by X-ray diffraction measurement and field emission scanning electron microscope observation. It was revealed that doped Al is substituted onto the Zn site of the ZnO crystalline structure in ZnO:Al films. - Highlights: ► An atmospheric pressure cold plasma generator generated stable glow discharge. ► We fabricated Al doped ZnO films on glass substrates using cold plasma. ► Al concentration measured by inductively coupled plasma atomic emission spectroscopy. ► The transmission spectrum and the resistivity of the films were measured. ► The microstructure of the films was studied.

  7. Weathering of post-impact hydrothermal deposits from the Haughton impact structure: implications for microbial colonization and biosignature preservation. (United States)

    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

  8. 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 (United States)

    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

  9. Herschel CHESS discovery of the fossil cloud that gave birth to the Trapezium and Orion KL (United States)

    López-Sepulcre, A.; Kama, M.; Ceccarelli, C.; Dominik, C.; Caux, E.; Fuente, A.; Alonso-Albi, T.


    Context. The Orion A molecular complex is a nearby (420 pc), very well studied stellar nursery that is believed to contain examples of triggered star formation. Aims: 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. Methods: 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. 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, and studied the implications of adopting the Orion Nebula extinction properties instead of the standard interstellar medium ones. Results: The detected absorption lines peak at a velocity of 9 km s-1, which is blue-shifted by 2 km s-1 with respect to the systemic velocity of OMC-2 FIR 4 (VLSR = 11.4 km s-1). The results of our modelling indicate that the foreground cloud is composed of predominantly neutral diffuse gas (nH = 100 cm-3) and is heavily irradiated by an external source of FUV that most likely arises from the nearby Trapezium OB association. The cloud is 6 pc thick and bears many similarities with the so-called C+ interface between Orion-KL and the Trapezium cluster, 2 pc south of OMC-2 FIR 4. Conclusions: We conclude that the foreground cloud we detected is an extension of the C+ interface seen in the direction of Orion KL, and interpret it to be the remains of the parental cloud of OMC-1, which extends from OMC-1 up to OMC-2.

  10. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VII. Further Insights into the Chromosphere and Corona

    Directory of Open Access Journals (Sweden)

    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

  11. Characteristic Elemental Composition of Oil Pigments using Instrumental Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Chung, Yong Sam; Kim, Sun Ha; Sun, Gwang Min; Lim, Jong Myung; Moon, Jong Hwa; Kim, Young Jin; Lim, Sung Jin; Song, Yu Na; Kim, Ken


    The principal aim of this study is to identify the applicability of instrumental neutron activation analysis as a non-destructive examination tool for the quantitative composition analysis associated with authentication, restoration, and conservation of art objects in the field of cultural heritage. Generally, the chemical composition of pigments are associated with the colors such as white, yellow, orange, red, green, blue and black, and it varies with raw materials of pigments. According to the colors of a different pigments, chemical compositions are as follows; for example, white pigments were used for a mixture of Pb(CO 3 ) 2 , PbSO 4 , PbO, Pb(OH) 2 , ZnO, ZnS, TiO 2 , BaSO 4 , CaCO 3 , Al 2 O 3 , As 2 S 3 , etc.; black pigments were series of carbon black, borne ash, MnO+Mn 2 O 3 , etc.; red pigments were Fe 2 O 3 , Pb 3 O 4 , HgS, PbMo 4 , CdS+CdSe, etc.; brown and yellow pigments were PbCrO 4 , ZnCrO 4 , CdS-ZnS, K 3 [Co(NO 2 ) 6 ], Pb(SbO 3 ) 2 , C 19 H 16 O 11 Mg, SrCrO 4 , etc.; green pigments were Cr 2 O 3 , Cr 2 O(OH) 4 , Cu(C 2 H 3 O 2 )-2Cu(OH) 2 ), Cr 2 O 3 -Al 2 O 3 -CoO, etc.; blue pigments were Fe 4 [Fe(CN) 6 ] 3 , CoO-Al 2 O 3 , Na 8 - 10 Al 6 Si 6 O 24 S 2-4 , etc. This first step is to obtain quantitative data on the concentrations of major, minor and trace elements in oil pigments and to explain pigment sources by statistical treatment as reported in many literatures. The determination of major, minor and micro elements in the subject materials are essential in many fields of basic science and technology as well as commercial and industrial fields. In particular, direct analysis of a sample offers a more effective investigation method in these fields. Instrumental neutron activation analysis (INAA) has an inherent advantage of being a non-destructive, simultaneously multi-elemental analysis with high accuracy and sensitivity. In order to characterize the elemental contents of art objects, the quantitative analysis of oil pigment series was

  12. Structure, equilibrium and ligand exchange dynamics in the binary and ternary dioxouranium(VI)-ethylenediamine-N,N'-diacetic acid-fluoride system: A potentiometric, NMR and X-ray crystallographic study. (United States)

    Palladino, Giuseppe; Szabó, Zoltán; Fischer, Andreas; Grenthe, Ingmar


    The structure, thermodynamics and kinetics of the binary and ternary uranium(VI)-ethylenediamine-N,N'-diacetate (in the following denoted EDDA) fluoride systems have been studied using potentiometry, 1H, 19F NMR spectroscopy and X-ray diffraction. The UO2(2+)-EDDA system could be studied up to -log[H3O+] = 3.4 where the formation of two binary complexes UO2(EDDA)(aq) and UO2(H3EDDA)3+ were identified, with equilibrium constants logbeta(UO2EDDA) = 11.63 +/- 0.02 and logbeta(UO2H3EDDA3+) = 1.77 +/- 0.04, respectively. In the ternary system the complexes UO2(EDDA)F-, UO2(EDDA)(OH)- and (UO2)2(mu-OH)2(HEDDA)2F2(aq) were identified; the latter through 19F NMR. 1H NMR spectra indicate that the EDDA ligand is chelate bonded in UO2(EDDA)(aq), UO2(EDDA)F- and UO2(EDDA)(OH)- while only one carboxylate group is coordinated in UO2(H3EDDA)3+. The rate and mechanism of the fluoride exchange between UO2(EDDA)F- and free fluoride was studied by 19F NMR spectroscopy. Three reactions contribute to the exchange; (i) site exchange between UO2(EDDA)F- and free fluoride without any net chemical exchange, (ii) replacement of the coordinated fluoride with OH- and (iii) the self dissociation of the coordinated fluoride forming UO2(EDDA)(aq); these reactions seem to follow associative mechanisms. (1)H NMR spectra show that the exchange between the free and chelate bonded EDDA is slow and consists of several steps, protonation/deprotonation and chelate ring opening/ring closure, the mechanism cannot be elucidated from the available data. The structure (UO2)2(EDDA)2(mu-H2EDDA) was determined by single crystal X-ray diffraction and contains two UO2(EDDA) units with tetracoordinated EDDA linked by H2EDDA in the "zwitterion" form, coordinated through a single carboxylate oxygen from each end to the two uranium atoms. The geometry of the complexes indicates that there is no geometric constraint for an associative ligand substitution mechanism.

  13. A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra (United States)

    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

  14. The pathway for serial proton supply to the active site of nitrogenase: enhanced density functional modeling of the Grotthuss mechanism. (United States)

    Dance, Ian


    Nitrogenase contains a well defined and conserved chain of water molecules leading to the FeMo cofactor (FeMo-co, an [Fe7MoCS9] cluster with bidentate chelation of Mo by homocitrate) that is the active site where N2 and other substrates are sequentially hydrogenated using multiple protons and electrons. The function of this chain is proposed to be a proton wire, serially translocating protons to triply-bridging S3B of FeMo-co, where, concomitant with electron transfer to FeMo-co, an H atom is generated on S3B. Density functional simulations of this proton translocation mechanism are reported here, using a large 269-atom model that includes all residues hydrogen bonded to and surrounding the water chain, and likely to influence proton transfer: three carboxylate O atoms of obligatory homocitrate are essential. The mechanism involves the standard two components of the Grotthuss mechanism, namely H atom slides that shift H3O(+) from one water site to the next, and HOH molecular rotations that convert backward (posterior) OH bonds in the water chain to forward (anterior) OH bonds. The topography of the potential energy surface for each of these steps has been mapped. H atom slides pass through very short (ca. 2.5 Å) O-H-O hydrogen bonds, while HOH rotations involve the breaking of O-HO hydrogen bonds, and the occurrence of long (up to 3.6 Å) separations between contiguous water molecules. Both steps involve low potential energy barriers, chain, occurring as ripples. These characteristics of the 'Grotthuss two-step', coupled with a buffering ability of two carboxylate O atoms of homocitrate, and combined with density functional characterisation of the final proton slide from the ultimate water molecule to S3B (including electron addition), have been choreographed into a complete mechanism for serial hydrogenation of FeMo-co. The largest potential barrier is estimated to be 14 kcal mol(-1). These results are discussed in the context of reactivity data for nitrogenase

  15. About opportunity of development of photo-diodes capable to work at 2326 sm-1 from carbon black filled polystyrene

    International Nuclear Information System (INIS)

    Akhmedov, U.Kh.; Tukhtaev, G.M.; Umirzakov, B.E.


    Full text: In essential progress in nano-electronics have resulted works connected with creation of active components of electronic engineering from cluster forms of carbon (CFC). For example, physical principles of reception of transistor effect from an individual molecule fullerene C 60 are already discussed, results of development of photo-diodes from system poly-thiophene - fullerene C 60 also are submitted. CFC usually synthesize separately. However, our researches have shown an opportunity of compulsory formation of some part of agglomerates of carbon black in final and intermediate products fullerene C 60 during preparation of composites of polystyrene (PS) at filling by its usual amorphous carbon black. Roentgenograms of initial composites, i.e. carbon black and PS, had only amorphous pieces, without what or crystal peaks whereas the roentgenogram of a composite had set of new peaks connected with crystallization. Calculations have shown conformity to within 1-2 % of size of inter plane distance of the most intensive peak in the roentgenogram of a composite 0.3599 nm with that distance for radius of molecule C 60 which makes 0.357 nm. IR-spectra of a composite with such strips of absorption as: 1434; 1174; 500 and 1650; 1577 sm -1 practically confirm presence of unary and double communications between atoms of carbon, characteristic for molecule C 60 . The inter plane distance under the roentgenogram of a composite equal 0.33588 nm to within 1-2 % corresponds to literary size of interlayer distance in such microtube equal 0.34 nm. Actually the technology of preparation applied by us in the given work, has resulted in formation multilayered in structure of this material. It agrees to data ESR of spectroscopy in a boundary layer of a composite ions H 3 O 2 , and H 5 O 2 are formed or donor-acceptor complexes, or with weak communication, for example, (H 2 O) 2 or with strong communication, for example. Results dielectric, ESR and IR-spectroscopy allow to count

  16. 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

    KAUST Repository

    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.

  17. Kinetics and mechanism of carbon-8 methylation of purine bases and nucleosides by methyl radical

    International Nuclear Information System (INIS)

    Zady, M.F.; Wong, J.L.


    The kinetics of homolytic methylation of the model purine compound caffeine at carbon-8 were determined as a function of several reaction variables. The methyl radical was generated from tert-butyl peracetate (BPA) either thermally (65 to 95 0 C) or photochemically (greater than 300 nm, 25 0 C). The thermal reaction k (25 0 C) was found to be 3.09 x 10 -8 s -1 from the linear log k (pseudo-first-order) vs. l/T plot. The light reactions using the 450- and 1200-W mercury lamps proceeded with k (25 0 C) 450- and 2160-fold greater, respectively. The derived activation energies are consistent with an S/sub E/Ar reaction. Increasing the concentration of caffeine from 0.25 M to 1.67 M in the presence of 3 molar equiv of BPA did not cause any side reaction. The pH-rate profile can be predicted by rate equations, which are derived on the basis of an electrophilic substitution occurring on the free base and conjugate acid of a heteroaromatic system. A competition study using tetrahydrofuran reveals the presence of a radical sigma complex IIIa and a charge transfer complex IIIb as intermediates for methylation under neutral and acidic conditions, respectively. Their rate-determining nature was indicated by the small positive kinetic isotope effect and the inverse solvent isotope effects: k/sub H 3 O + //k/sub D 3 O + / = 0.87 and k/sub H 2 O//k/sub D 2 O/ = 0.32. Thus, in acidic medium, a preequilibrium proton transfer to form the caffeine conjugate acid precedes the rate-controlling formation of IIIb. In neutral solution, the rate-determining step appears to be the protonation of the radical nitrogen in IIIa converting it to III. The acid-catalyzed caffeine-BPA reaction was shown to be general for other purines such as adenine, adenosine, guanine, guanosine, hypoxanthine, and inosine

  18. The ISO Long Wavelength Spectrometer line spectrum of VY Canis Majoris and other oxygen-rich evolved stars (United States)

    Polehampton, E. T.; Menten, K. M.; van der Tak, F. F. S.; White, G. J.


    Context. The far-infrared spectra of circumstellar envelopes around various oxygen-rich stars were observed using the ISO Long Wavelength Spectrometer (LWS). These have been shown to be spectrally rich, particularly in water lines, indicating a high H2O abundance. Aims: We have examined high signal-to-noise ISO LWS observations of the luminous supergiant star, VY CMa, with the aim of identifying all of the spectral lines. By paying particular attention to water lines, we aim to separate the lines due to other species, in particular, to prepare for forthcoming observations that will cover the same spectral range using Herschel PACS and at higher spectral resolution using Herschel HIFI and SOFIA. Methods: We have developed a fitting method to account for blended water lines using a simple weighting scheme to distribute the flux. We have used this fit to separate lines due to other species which cannot be assigned to water. We have applied this approach to several other stars which we compare with VY CMa. Results: We present line fluxes for the unblended H2O and CO lines, and present detections of several possible ν2=1 vibrationally excited water lines. We also identify blended lines of OH, one unblended and several blended lines of NH3, and one possible detection of H3O+. Conclusions: The spectrum of VY CMa shows a detection of emission from virtually every water line up to 2000 K above the ground state, as well as many additional higher energy and some vibrationally excited lines. A simple rotation diagram analysis shows large scatter (probably due to some optically thick lines). The fit gives a rotational temperature of 670+210-130 K, and lower limit on the water column density of (7.0±1.2) × 1019 cm-2. We estimate a CO column density ~100 times lower, showing that water is the dominant oxygen carrier. The other stars that we examined have similar rotation temperatures, but their H2O column densities are an order of magnitude lower (as are the mass loss rates

  19. Challenges of biological sample preparation for SIMS imaging of elements and molecules at subcellular resolution (United States)

    Chandra, Subhash


    Secondary ion mass spectrometry (SIMS) based imaging techniques capable of subcellular resolution characterization of elements and molecules are becoming valuable tools in many areas of biology and medicine. Due to high vacuum requirements of SIMS, the live cells cannot be analyzed directly in the instrument. The sample preparation, therefore, plays a critical role in preserving the native chemical composition for SIMS analysis. This work focuses on the evaluation of frozen-hydrated and frozen freeze-dried sample preparations for SIMS studies of cultured cells with a CAMECA IMS-3f dynamic SIMS ion microscope instrument capable of producing SIMS images with a spatial resolution of 500 nm. The sandwich freeze-fracture method was used for fracturing the cells. The complimentary fracture planes in the plasma membrane were characterized by field-emission secondary electron microscopy (FESEM) in the frozen-hydrated state. The cells fractured at the dorsal surface were used for SIMS analysis. The frozen-hydrated SIMS analysis of individual cells under dynamic primary ion beam (O 2+) revealed local secondary ion signal enhancements correlated with the water image signals of 19(H 3O) +. A preferential removal of water from the frozen cell matrix in the Z-axis was also observed. These complications render the frozen-hydrated sample type less desirable for subcellular dynamic SIMS studies. The freeze-drying of frozen-hydrated cells, either inside the instrument or externally in a freeze-drier, allowed SIMS imaging of subcellular chemical composition. Morphological evaluations of fractured freeze-dried cells with SEM and confocal laser scanning microscopy (CLSM) revealed well-preserved mitochondria, Golgi apparatus, and stress fibers. SIMS analysis of fractured freeze-dried cells revealed well-preserved chemical composition of even the most highly diffusible ions like K + and Na + in physiologically relevant concentrations. The high K-low Na signature in individual cells

  20. 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

    International Nuclear Information System (INIS)

    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 Fe 3+ 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 Fe 2+ -Fe(H 2 O) 6 3+ , Fe 2+ -Fe(OH)(H 2 O) 5 2+ , and Fe 2+ -Fe(OH) 2 (H 2 O) + 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(H 2 O) 6 2+ -Fe(OH) n (H 2 O) 6-n (3-n)+ complexes interacting through H 3 O 2 - bridges do not have large electronic couplings

  1. Detection methods for atoms and radicals in the gas phase (United States)

    Hack, W.

    This report lists atoms and free radicals in the gas phase which are of interest for environmental and flame chemistry and have been detected directly. The detection methods which have been used are discussed with respect to their range of application, specificity and sensitivity. In table 1, detection methods for the five atoms of group IV (C, Si, Ge, Sn, Pb) and about 60 radicals containing at least one atom of group IV are summarized (CH, Cd, Cf, CC1, CBr, Cn, Cs, CSe, CH2, CD2, Chf, Cdf, CHC1, CHBr, CF2, CC12, CBr2, CFC1, CFBr, CH3, CD3, CF3, CH2F, CH2C1, CH2Br, CHF2, CHC12, CHBr2, Hco, Fco, CH30, CD30, CH2OH, CH3S, Nco, CH4N, CH302, CF302; C2, C2N, C2H, C20, C2HO, C2H3, C2F3, C2H5, C2HsO, C2H4OH, CH3CO, CD3CO, C2H3O, C2H502, CH3COO2, C2H4N, C2H6N, C3; Si, SiF, SiF2, SiO, SiC, Si2; Ge, GeC, GeO, GeF, GeF2, GeCl2, Sn, SnF, SnO, SnF2, Pb, PbF, PbF2, PbO, PbS). In table 2 detection methods for about 25 other atoms and 60 radicals are listed: (H, D, O, O2, Oh, Od, HO2, DO2, F, Ci, Br, I, Fo, Cio, BrO, Io, FO2, C1O2, Li, Na, K, Rb, Cs, N, N3, Nh, Nd, Nf, Nci, NBr, NH2, ND2, Nhd, Nhf, NF2, NC12, N2H3, No, NO2, NO3, Hno, Dno, P, Ph, Pd, Pf, Pci, PH2, PD2, PF2, Po, As, AsO, AsS, Sb, Bi, S, S2, Sh, Sd, Sf, SF2, So, Hso, Dso, Sn, Se, Te, Se2, SeH, SeD, SeF, SeO, SeS, SeN, TeH, TeO, Bh, BH2, Bo, Bn, B02, Cd, Hg, UF5). The tables also cite some recent kinetic applications of the various methods.

  2. Poly[4,4'-(propane-1,3-diyl)dipyridinium bis{tetraaquabis(μ2-5-carboxybenzene-1,2,4-tricarboxylato)bis[μ2-1,3-bis(4-pyridyl)propane]dicobalt(II)} pentahydrate]. (United States)

    Atria, Ana María; Corsini, Gino; Garland, Maria Teresa; Baggio, Ricardo


    The title polymeric compound, {(C(13)H(16)N(2))[Co(C(10)H(3)O(8))(C(13)H(14)N(2))(H(2)O)(2)](2)·5H(2)O}(n), is an ionic structure comprising an anionic two-dimensional mesh characterized by a {[Co(Hbtc)(bpp)(H(2)O)(2)](-)}(2) motif [Hbtc is 5-carboxybenzene-1,2,4-tricarboxylate and bpp is 1,3-bis(4-pyridyl)propane], with interspersed 4,4'-(propane-1,3-diyl)dipyridinium cations, denoted (H(2)bpp)(2+), and water molecules providing the charge balance and structure stabilization. The reticular mesh consists of two independent types of [Co(H(2)O)(2)](2+) cationic nodes (lying on inversion centres), interconnected in the [101] direction by two independent sets of neutral bridging bpp ligands, both types of ligands being split by non-equivalent twofold axes. One set is formed by genuinely symmetric moieties, while those in the second set are only symmetric by disorder in the central propane bridge. These chains contain only one type of Co(II) centre and one type of bpp ligand; the metal cations therein are laterally bridged by Hbtc anions, thus forming transverse chains of alternating types of Co(II) cations. The elemental motif of the resulting grid is a highly distorted parallelogram, with metal-metal distances of 13.5242 (14) Å in the bpp direction and 9.105 (2) Å in the Hbtc direction, and a large internal angle of 138.42 (18)°. These two-dimensional structures have a profusion of hydrogen-bonding interactions with each other, either directly (with the aqua molecules as donors and the Hbtc anions as acceptors) or mediated by the unbound (H(2)bpp)(2+) cations and water molecules of hydration. These interactions generate a very complex hydrogen-bonding scheme involving all of the available N-H and O-H groups and which links these two-dimensional grids into a three-dimensional network.

  3. The ToF-ACSM: a portable aerosol chemical speciation monitor with TOFMS detection

    Directory of Open Access Journals (Sweden)

    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.

  4. Quantification of Hydroxyl Radical reactivity in the urban environment using the Comparative Reactivity Method (CRM) (United States)

    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

  5. Relative Order of Sulfuric Acid, Bisulfate, Hydronium, and Cations at the Air-Water Interface. (United States)

    Hua, Wei; Verreault, Dominique; Allen, Heather C


    Sulfuric acid (H2SO4), bisulfate (HSO4(-)), and sulfate (SO4(2-)) are among the most abundant species in tropospheric and stratospheric aerosols due to high levels of atmospheric SO2 emitted from biomass burning and volcanic eruptions. The air/aqueous interfaces of sulfuric acid and bisulfate solutions play key roles in heterogeneous reactions, acid rain, radiative balance, and polar stratospheric cloud nucleation. Molecular-level knowledge about the interfacial distribution of these inorganic species and their perturbation of water organization facilitates a better understanding of the reactivity and growth of atmospheric aerosols and of the aerosol surface charge, thus shedding light on topics of air pollution, climate change, and thundercloud electrification. Here, the air/aqueous interface of NaHSO4, NH4HSO4, and Mg(HSO4)2 salt solutions as well as H2SO4 and HCl acid solutions are investigated by means of vibrational sum frequency generation (VSFG) and heterodyne-detected (HD) VSFG spectroscopy. VSFG spectra of all acid solutions show higher SFG response in the OH-bonded region relative to neat water, with 1.1 M H2SO4 being more enhanced than 1.1 M HCl. In addition, VSFG spectra of bisulfate salt solutions highly resemble that of the dilute H2SO4 solution (0.26 M) at a comparable pH. HD-VSFG (Im χ((2))) spectra of acid and bisulfate salt solutions further reveal that hydrogen-bonded water molecules are oriented preferentially toward the bulk liquid phase. General agreement between Im χ((2)) spectra of 1.1 M H2SO4 and 1.1 M HCl acid solutions indicate that HSO4(-) ions have a similar surface preference as that of chloride (Cl(-)) ions. By comparing the direction and magnitude of the electric fields arising from the interfacial ion distributions and the concentration of each species, the most reasonable relative surface preference that can be deduced from a simplified model follows the order H3O(+) > HSO4(-) > Na(+), NH4(+), Mg(2+) > SO4(2-). Interestingly

  6. Origins Space Telescope: HEterodyne Receiver for OST (HERO) (United States)

    Bergin, Edwin; Wiedner, Martina; Laurens, Andre; Gerin, Maryvonne; HERO team, Origins Space Telescope Science and Technology Definition Team


    The Origins Space Telescope (OST) is a mission concept for the Far-Infrared Surveyor, one of the four science and technology definition studies selected by NASA HQ for the 2020 Astronomy and Astrophysics Decadal survey. The OST study will encompass two mission concepts (poster by A. Cooray). Concept 1 is an extremely versatile observatory with 5 science instruments, of which the HEterodyne Receivers for OST (HERO) is one.HERO’s main targets are high spectral resolution observations (Dl/l up to 107 or Dv = 0.03km/s) of water to follow its trail from cores to YSOs as well as H2O and HDO observations on comets to explore the origins of water. HERO will probe all neutral ISM phases using cooling lines ([CII], [OI]) and hydrides as probes of CO-dark H2 (CH, HF). HERO will reveal how molecular clouds and filaments form in the local ISM up to nearby galaxies. HERO will enable detailed understanding of feedback mechanisms : shocks, cosmic rays, UV induced feedback and will provide a map of the cosmic ray ionization rate in the Galaxy and nearby galaxies using molecular ions (ArH+, OH+, H3O+).In order to achieve these observational goals, HERO will cover an extremely wide frequency range from 468 to 2700 GHz (641 to 111microns) and a window around the OI line at 4563 to 4752GHz (66 to 63 microns). It will consist of very large focal plane arrays of 128 pixels between 900 - 2700 GHz and at 4.7 THz, and 32 pixels for the 468 to 900 GHz range. The instrument is exploiting Herschel/HIFI heritage, but will go well beyond HIFIs capacities. HERO’s large arrays require low dissipation and low power components. The HERO concept makes use of the latest cryogenic SiGe amplifier technology, as well as CMOS technology for the backends with 2 orders of magnitude lower power. Advances in Local Oscillator technology have also been taken into account and ambitious, but realistic assumptions have been made for future amplifier multiplier chains going up to 4.7 THz.Origins will enable

  7. Electrolytic conductivity-the hopping mechanism of the proton and beyond

    International Nuclear Information System (INIS)

    Gileadi, E.; Kirowa-Eisner, E.


    The hopping mechanism of electrolytic conductivity is analyzed, employing mixtures of two solvents: one that sustains the hopping mechanism and the other that does not inhibit it directly, but interferes with it by diluting the solvent that sustains hopping. Measurement of the equivalent conductivity shows that the excess proton conductivities of H 3 O + and OH - increases with increasing temperature, although the number of hydrogen bonds is known to decrease. In mixtures of acetonitrile with water, proton hopping does not start until a threshold concentration of about 20 vol.% water has been reached, while no such threshold concentration is observed upon addition of methanol to acetonitrile. It is concluded that in the former the proton is transferred to a cluster of water molecules, which can be formed only if there is enough water in the solvent mixture. This observation leads to the concept of mono-water, which is the state of water molecules when they constitute a small minority in the solvent mixtures, as opposed to bulk water, which consists of clusters of variable sizes. Systems in which a hopping mechanism of heavy ions has been observed include Br - /Br 2 and I - /I 2 . In these cases the triple ions Br 3 - and I 3 - , respectively are formed, and serve as the mediators for the transfer of the simple halogen ion. A very large increase of conductivity was observed upon solidification of the Br - /Br 3 - system, probably caused by favorable linear alignment of ions in the solid. The conductivity of acidified methanol decreases upon addition of water, because the affinity of the proton to water is higher than to methanol, thus water can act as a scavenger for protons. This behavior exemplifies a general observation, namely that conductivity by hopping can only occur when the Gibbs energy of the system does not change significantly following ion transfer; otherwise the ions would be trapped in the more stable state, hindering further propagation by hopping

  8. Synthesis and characterization of one- to three-dimensional compounds composed of paradodecatungstate-B cluster and transition metals as linkers

    International Nuclear Information System (INIS)

    Sun Chunyan; Liu Shuxia; Xie Linhua; Wang Chunling; Gao Bo; Zhang Chundan; Su Zhongmin


    Three new extended frameworks built from paratungstate and transition metals have been synthesized and characterized. In the compound Na 8 [{Cd (H 2 O) 2 }(H 2 W 12 O 42 )].32H 2 O (1), two neighboring paratungstate-B ions [H 2 W 12 O 42 ] 10- are linked by [Cd(H 2 O) 2 ] 2+ units, leading to the formation of infinite one-dimensional (1D) anion chain [{Cd(H 2 O) 2 }(H 2 W 12 O 42 )] n 8n- . The anion [{Co(H 2 O) 3 }{Co(H 2 O) 4 }(H 2 W 12 O 42 )] n 6n- of the compound Na 6 [{Co(H 2 O) 3 }{Co(H 2 O) 4 }(H 2 W 12 O 42 )].29H 2 O (2) shows a layer-like (2D) structure in which paratungstate-B units are linked by CoO 6 octahedra, while the anion [{Co(H 2 O) 3 } 3 (H 2 W 12 O 42 )] n 4n- of the compound (H 3 O + ) 3 [{Na(H 2 O) 4 }{Co(H 2 O) 4 } 3 (H 2 W 12 O 42 )].24.5H 2 O (3) is a three-dimensional (3D) anionic polymer that consists of paratungstate-B units linked by CoO 6 octahedra. Compound 3 can reversibly adsorb and desorb water molecules leading to the color reversibly change from pink to violet. The preliminary magnetic measurement and electrochemical properties of compounds are performed. The crystal structure of unexpected product Na 4 [NiW 6 O 24 H 6 ].13H 2 O (4) is described here for the rare report of crystal structure information on the Anderson-type polyoxotungstate which has nickel as a heteroatom. - Graphical abstract: Three new compounds with one- to three-dimensional extended frameworks built from [H 2 W 12 O 42 ] 10- anion and transition metals have been synthesized and characterized by elemental analyses, X-ray single-crystal analyses, magnetic measurement, XRPD, and cyclic voltammetry measurements. The cobalt containing compound exhibits interesting reversible sorption/desorption of water molecules

  9. Challenges of biological sample preparation for SIMS imaging of elements and molecules at subcellular resolution

    International Nuclear Information System (INIS)

    Chandra, Subhash


    Secondary ion mass spectrometry (SIMS) based imaging techniques capable of subcellular resolution characterization of elements and molecules are becoming valuable tools in many areas of biology and medicine. Due to high vacuum requirements of SIMS, the live cells cannot be analyzed directly in the instrument. The sample preparation, therefore, plays a critical role in preserving the native chemical composition for SIMS analysis. This work focuses on the evaluation of frozen-hydrated and frozen freeze-dried sample preparations for SIMS studies of cultured cells with a CAMECA IMS-3f dynamic SIMS ion microscope instrument capable of producing SIMS images with a spatial resolution of 500 nm. The sandwich freeze-fracture method was used for fracturing the cells. The complimentary fracture planes in the plasma membrane were characterized by field-emission secondary electron microscopy (FESEM) in the frozen-hydrated state. The cells fractured at the dorsal surface were used for SIMS analysis. The frozen-hydrated SIMS analysis of individual cells under dynamic primary ion beam (O 2 + ) revealed local secondary ion signal enhancements correlated with the water image signals of 19 (H 3 O) + . A preferential removal of water from the frozen cell matrix in the Z-axis was also observed. These complications render the frozen-hydrated sample type less desirable for subcellular dynamic SIMS studies. The freeze-drying of frozen-hydrated cells, either inside the instrument or externally in a freeze-drier, allowed SIMS imaging of subcellular chemical composition. Morphological evaluations of fractured freeze-dried cells with SEM and confocal laser scanning microscopy (CLSM) revealed well-preserved mitochondria, Golgi apparatus, and stress fibers. SIMS analysis of fractured freeze-dried cells revealed well-preserved chemical composition of even the most highly diffusible ions like K + and Na + in physiologically relevant concentrations. The high K-low Na signature in individual cells

  10. Periodic Density Functional Theory Study of the Structure, Raman Spectrum, and Mechanical Properties of Schoepite Mineral. (United States)

    Colmenero, Francisco; Cobos, Joaquín; Timón, Vicente


    The structure and Raman spectrum of schoepite mineral, [(UO 2 ) 8 O 2 (OH) 12 ]·12H 2 O, was studied by means of theoretical calculations. The computations were carried out by using density functional theory with plane waves and pseudopotentials. A norm-conserving pseudopotential specific for the U atom developed in a previous work was employed. Because it was not possible to locate H atoms directly from X-ray diffraction (XRD) data by structure refinement in previous experimental studies, all of the positions of the H atoms in the full unit cell were determined theoretically. The structural results, including the lattice parameters, bond lengths, bond angles, and powder XRD pattern, were found to be in good agreement with their experimental counterparts. However, the calculations performed using the unit cell designed by Ostanin and Zeller in 2007, involving half of the atoms of the full unit cell, led to significant errors in the computed powder XRD pattern. Furthermore, Ostanin and Zeller's unit cell contains hydronium ions, H 3 O + , which are incompatible with the experimental information. Therefore, while the use of this schoepite model may be a very useful approximation requiring a much smaller amount of computational effort, the full unit cell should be used to study this mineral accurately. The Raman spectrum was also computed by means of density functional perturbation theory and compared with the experimental spectrum. The results were also in agreement with the experimental data. A normal-mode analysis of the theoretical spectra was performed to assign the main bands of the Raman spectrum. This assignment significantly improved the current empirical assignment of the bands of the Raman spectrum of schoepite mineral. In addition, the equation of state and elastic properties of this mineral were determined. The crystal structure of schoepite was found to be stable mechanically and dynamically. Schoepite can be described as a brittle material exhibiting

  11. Nicotiana tabacum as model for ozone - plant surface reactions (United States)

    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

  12. Ion-Exchange Processes and Mechanisms in Glasses

    International Nuclear Information System (INIS)

    McGrail, B.P.; Icenhower, J.P.; Darab, J.G.; Shuh, D.K.; Baer, D.R.; Shutthanandan, V.; Thevuthasan, S.; Engelhard, M.H.; Steele, J.L.; Rodriguez, E.A.; Liu, P.; Ivanov, K.E.; Booth, C.H.; Nachimuthu, P.


    Leaching of alkalis from glass is widely recognized as an important mechanism in the initial stages of glass-water interactions. Pioneering experimental studies [1-3] nearly thirty-five years ago established that alkali (designated as M + ) are lost to solution more rapidly than network-forming cations. The overall chemical reaction describing the process can be written as: (triple b ond)Si-O-M + H + → (triple b ond)Si-OH + M + (1) or (triple b ond)Si-O-M + H 3 O + → (triple b ond)Si-OH + M + + H 2 O. (2) Doremus and coworkers [4-7] fashioned a quantitative model where M + ions in the glass are exchanged for counter-diffusing H 3 O + or H + . Subsequent investigations [8], which have relied heavily on reaction layer analysis, recognized the role of H 2 O molecules in the alkali-exchange process, without minimizing the importance of charged hydrogen species. Beginning in the 1980s, however, interest in M + -H + exchange reactions in silicate glasses diminished considerably because important experimental observations showed that network hydrolysis and dissolution rates were principally controlled by the chemical potential difference between the glass and solution (chemical affinity) [9]. For nuclear waste glasses, formation of alteration products or secondary phases that remove important elements from solution, particularly Si, was found to have very large impacts on glass dissolution rates [10,11]. Consequently, recent work on glass/water interactions has focused on understanding this process and incorporating it into models [12]. The ion-exchange process has been largely ignored because it has been thought to be a short duration, secondary or tertiary process that had little or no bearing on long-term corrosion or radionuclide release rates from glasses [13]. The only significant effect identified in the literature that is attributed to alkali ion exchange is an increase in solution pH in static laboratory tests conducted at high surface area-to-volume ratios

  13. Chemical Characterization of Submicron Aerosol Particles in São Paulo, Brazil (United States)

    Ferreira De Brito, J.; Rizzo, L. V.; Godoy, J.; Godoy, M. L.; de Assunção, J. V.; Alves, N. D.; Artaxo, P.


    pattern allows characterization of organic aerosol processing, e.g., m/z 43 (C2H3O+ and/or C3H7+, depending on the source and level or processing) and m/z 44 (mostly CO2+). The parameter f43 and f44, defined as the signal on the corresponding m/z relative to total organic, provides a metric for aerosol processing. As such, the organic aerosol sampled at the University site has shown to be considerably more processed than at the Downtown site, with the parameter f44=0.19 in the former and 0.14 in the latter. Interestingly, little difference has been observed in the f43 parameter, being 0.035 at the University site and 0.036 at the Downtown site. PMF analysis indicates large dominance of SOA relative to POA on both sites. This study shall provide an overview of the atmospheric dynamics of this megacity and its unique fleet, never characterized in such details before.

  14. Roles of Bridging Ligand Topology and Conformation in Controlling Exchange Interactions between Paramagnetic Molybdenum Fragments in Dinuclear and Trinuclear Complexes. (United States)

    Ung VÂ, V&acaron;n Ân; Cargill Thompson, Alexander M. W.; Bardwell, David A.; Gatteschi, Dante; Jeffery, John C.; McCleverty, Jon A.; Totti, Federico; Ward, Michael D.


    The magnetic properties of two series of dinuclear complexes, and one trinuclear complex, have been examined as a function of the bridging pathway between the metal centers. The first series of dinuclear complexes is [{Mo(V)(O)(Tp)Cl}(2)(&mgr;-OO)], where "OO" is [1,4-O(C(6)H(4))(n)O](2)(-) (n = 1, 1; n = 2, 3), [4,4'-O(C(6)H(3)-2-Me)(2)O](2)(-) (4), or [1,3-OC(6)H(4)O](2)(-) (2) [Tp = tris(3,5-dimethylpyrazolyl)hydroborate]. The second series of dinuclear complexes is [{Mo(I)(NO)(Tp)Cl}(2)(&mgr;-NN)], where "NN" is 4,4'-bipyridyl (5), 3,3'-dimethyl-4,4'-bipyridine (6), 3,8-phenanthroline (7), or 2,7-diazapyrene (8). The trinuclear complex is [{Mo(V)(O)(Tp)Cl}(3)(1,3,5-C(6)H(3)O(3))] (9), whose crystal structure was determined [9.5CH(2)Cl(2): C(56)H(81)B(3)Cl(13)Mo(3)N(18)O(6); monoclinic, P2(1)/n; a = 13.443, b = 41.46(2), c = 14.314(6) Å; beta = 93.21(3) degrees; V = 7995(5) Å(3); Z = 4; R(1) = 0.106]. In these complexes, the sign and magnitude of the exchange coupling constant J is clearly related to both the topology and the conformation of the bridging ligand [where J is derived from H = -JS(1)().S(2)() for 1-8 and H = -J(S(1)().S(2)() + S(2)().S(3)() + S(1)().S(3)()) for 9]. The values are as follows: 1, -80 cm(-)(1); 2, +9.8 cm(-)(1); 3, -13.2 cm(-)(1); 4, -2.8 cm(-)(1); 5, -33 cm(-)(1); 6, -3.5 cm(-)(1); 7, -35.6 cm(-)(1); 8, -35.0 cm(-)(1); 9, +14.4 cm(-)(1). In particular the following holds: (1) J is negative (antiferromagnetic exchange) across the para-substituted bridges ligands of 1 and 3-8 but positive (ferromagnetic exchange) across the meta-substituted bridging ligands of 2 and 9. (2) J decreases in magnitude dramatically as the bridging ligand conformation changes from planar to twisted (compare 3 and 4, or 6 and 8). These observations are consistent with a spin-polarization mechanism for the exchange interaction, propagated across the pi-system of the bridging ligand by via overlap of bridging ligand p(pi) orbitals with the d(pi) magnetic

  15. Recuperação de gotejadores obstruídos devido à utilização de águas ferruginosas Recovery of drippers clogged by use of water high in iron content

    Directory of Open Access Journals (Sweden)

    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

  16. Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O(3P)+allyl radical intermediate

    International Nuclear Information System (INIS)

    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 experiment

  17. Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O(3P)+allyl radical intermediate (United States)

    FitzPatrick, Benjamin L.; Alligood, Bridget W.; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim-Min, Jr.


    This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H2COCH)CH2Cl. The three dominant photoproduct channels analyzed are c-(H2COCH)CH2+Cl, c-(H2COCH)+CH2Cl, and C3H4O+HCl. In the second channel, the c-(H2COCH) photofission product is a higher energy intermediate on C2H3O 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, H2CCO. The final primary photodissociation pathway HCl+C3H4O evidences a recoil kinetic energy distribution similar to that of four-center HCl elimination in chlorinated alkenes, so is assigned to production of c-(H2COC)=CH2; the epoxide product is formed with enough vibrational energy to isomerize to acrolein and dissociate. The paper then analyzes the dynamics of the C3H5O 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(P3)+allyl bimolecular reaction when the O atom adds to an end C atom. We focus on the HCO+C2H4 and H2CO+C2H3 product channels from this radical intermediate in this report. Analysis of the velocity distribution of the momentum-matched signals from the HCO+C2H4 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 H2CO+C2H3 product channel of the O(P3)+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 experiment. The data also reveal substantial branching to an HCCH+H3

  18. CO gas sensing properties of In_4Sn_3O_1_2 and TeO_2 composite nanoparticle sensors

    International Nuclear Information System (INIS)

    Mirzaei, Ali; Park, Sunghoon; Sun, Gun-Joo; Kheel, Hyejoon; Lee, Chongmu


    Highlights: • In4Sn3O12–TeO2 composite nanoparticles were synthesized via a facile hydrothermal route. • The response of the In4Sn3O12–TeO2 composite sensor to CO was stronger than the pristine In4Sn3O12 sensor. • The response of the In4Sn3O12–TeO2 composite sensor to CO was faster than the pristine In4Sn3O12 sensor. • The improved sensing performance of the In4Sn3O12–TeO2 nanocomposite sensor is discussed in detail. • The In4Sn3O12-based nanoparticle sensors showed selectivity to CO over NH3, HCHO and H2. - Abstract: A simple hydrothermal route was used to synthesize In_4Sn_3O_1_2 nanoparticles and In_4Sn_3O_1_2–TeO_2 composite nanoparticles, with In(C_2H_3O_2)_3, SnCl_4, and TeCl_4 as the starting materials. The structure and morphology of the synthesized nanoparticles were examined by X-ray diffraction and scanning electron microscopy (SEM), respectively. The gas-sensing properties of the pure and composite nanoparticles toward CO gas were examined at different concentrations (5–100 ppm) of CO gas at different temperatures (100–300 °C). SEM observation revealed that the composite nanoparticles had a uniform shape and size. The sensor based on the In_4Sn_3O_1_2–TeO_2 composite nanoparticles showed stronger response to CO than its pure In_4Sn_3O_1_2 counterpart. The response of the In_4Sn_3O_1_2–TeO_2 composite-nanoparticle sensor to 100 ppm of CO at 200 °C was 10.21, whereas the maximum response of the In_4Sn_3O_1_2 nanoparticle sensor was 2.78 under the same conditions. Furthermore, the response time of the composite sensor was 19.73 s under these conditions, which is less than one-third of that of the In_4Sn_3O_1_2 sensor. The improved sensing performance of the In_4Sn_3O_1_2–TeO_2 nanocomposite sensor is attributed to the enhanced modulation of the potential barrier height at the In_4Sn_3O_1_2–TeO_2 interface, the stronger oxygen adsorption of p-type TeO_2, and the formation of preferential adsorption sites.

  19. Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces. (United States)

    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.

  20. Selective-Reagent-Ionization Mass Spectrometry: New Prospects for Atmospheric Research (United States)

    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

  1. Ozone fumigation under dark/light conditions of Norway Spruce (Picea Abies) and Scots Pine (Pinus Sylvestris) (United States)

    Canaval, Eva; Jud, Werner; Hansel, Armin


    Norway Spruce (Picea abies) and Scots Pine (Pinus sylvestris) represent dominating tree species in the northern hemisphere. Thus, the understanding of their ozone sensitivity in the light of the expected increasing ozone levels in the future is of great importance. In our experiments we investigated the emissions of volatile organic compounds (VOCs) of 3-4 year old Norway Spruce and Scots Pine seedlings under ozone fumigation (50-150 ppbv) and dark/light conditions. For the experiments the plants were placed in a setup with inert materials including a glass cuvette equipped with a turbulent air inlet and sensors for monitoring a large range of meteorological parameters. Typical conditions were 20-25°C and a relative humidity of 70-90 % for both plant species. A fast gas exchange rate was used to minimize reactions of ozone in the gas phase. A Switchable-Reagent-Ion-Time-of-Flight-MS (SRI-ToF-MS) was used to analyze the VOCs at the cuvette outlet in real-time during changing ozone and light levels. The use of H3O+ and NO+ as reagent ions allows the separation of certain isomers (e.g. aldehydes and ketones) due to different reaction pathways depending on the functional groups of the molecules. Within the Picea abies experiments the ozone loss, defined as the difference of the ozone concentration between cuvette inlet and outlet, remained nearly constant at the transition from dark to light. This indicates that a major part of the supplied ozone is depleted non-stomatally. In contrast the ozone loss increased by 50 % at the transition from dark to light conditions within Pinus sylvestris experiments. In this case the stomata represent the dominant loss channel. Since maximally 0.1% of the ozone loss could be explained by gas phase reactions with monoterpenes and sesquiterpenes, we suggest that ozone reactions on the surface of Picea abies represent the major sink in this case and lead to an light-independent ozone loss. This is supported by the fact that we detected

  2. Investigating the pathway for the photochemical formation of VOCs in presence of an organic monolayer at the air/water interface. (United States)

    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

  3. Mechanical behavior of porous ceramic disks

    International Nuclear Information System (INIS)

    Pucheu, M.A; Sandoval, M.L; Tomba Martinez, A.G; Camerucci, M.A


    The mechanical behavior of green and sintered porous ceramic materials, obtained by processing control, in relation to the microstructure developed was studied. Disks in green state were prepared by direct thermal consolidation of aqueous suspensions of kaolin, talc and alumina (preliminary mixture of cordierite) with the addition of different starches as consolidating/binding agents and as formers of pores at high temperature. Commercial kaolin (C-80 washed kaolin, Piedra Grande S.A., Argentina), micronized talc (Talc 40, China), calcinated alumina (A2G ALCOA, USA) and commercial potato, manioc, modified potato and corn starches were used as raw materials. The preliminary ceramic mixture was prepared based on the composition in oxides of the ceramic raw materials, in a relationship that was as close as possible to stoichiometric cordierite. Aqueous suspensions of the powders (65% solids; 0.5% sodium naphtolenosulfonate; 1% Dolapix with 17% of each kind of starch were prepared by intensive mechanical mixing, homogenization (ball mills, 2h) and extracting the air with vacuum 20 min. Disks were prepared (diameter=20-30 mm; thickness=3-4 mm) by thermal consolidation of the suspensions in steel molds at the maximum swelling factor temperature (Tms) for each starch (75- 85 o C) for 4h and, later drying at 50 o C, 12h. The porous materials of cordierite were obtained by calcination and reaction-sintering using a controlled thermal cycle: 1 o C/min up to 650 o C, 2h; 3 o C/min up to 1330 o C, 4h and 5 o C/min to room temperature. The characterization of the porous materials in green and sintered state was done by measuring density and apparent porosity, distribution of pore sizes and SEM. The mechanical resistance of the materials in green and sintered state was evaluated in diametrical compression (Instron universal testing machine servo hydraulic model 8501), in position control (0.1-0.2 mm/min) with a statistical number of test pieces, at room air temperature. The

  4. Two earth years of Moessbauer studies of the surface of Mars with MIMOS II

    International Nuclear Information System (INIS)

    Klingelhoefer, G.; Morris, R. V.; De Souza, P. A.; Rodionov, D.; Schroeder, C.


    The element iron plays a crucial role in the study of the evolution of matter from an interstellar cloud to the formation and evolution of the planets. In the Solar System iron is the most abundant metallic element. It occurs in at least three different oxidation states: Fe(0) (metallic iron), Fe(II) and Fe(III). Fe(IV) and Fe(VI) compounds are well known on Earth, and there is a possibility for their occurrence on Mars. In January 2004 the USA space agency NASA landed two rovers on the surface of Mars, both carrying the Mainz Moessbauer spectrometer MIMOS II. They performed for the first time in-situ measurements of the mineralogy of the Martian surface, at two different places on Mars, Meridiani Planum and Gusev crater, respectively, the landing sites of the Mars-Exploration-Rovers (MER) Opportunity and Spirit. After about two Earth years or one Martian year of operation the Moessbauer (MB) spectrometers on both rovers have acquired data from more than 150 targets (and more than thousand MB spectra) at each landing site. The scientific measurement objectives of the Moessbauer investigation are to obtain for rock, soil, and dust (1) the mineralogical identification of iron-bearing phases (e.g., oxides, silicates, sulfides, sulfates, and carbonates), (2) the quantitative measurement of the distribution of iron among these iron-bearing phases (e.g., the relative proportions of iron in olivine, pyroxenes, ilmenite and magnetite in a basalt), (3) the quantitative measurement of the distribution of iron among its oxidation states (e.g., Fe 2+ , Fe 3+ , and Fe 6+ ), and (4) the characterization of the size distribution of magnetic particles. Special geologic targets of the Moessbauer investigation are dust collected by the Athena magnets and interior rock and soil surfaces exposed by the Athena Rock Abrasion Tool and by trenching with rover wheels. The Moessbauer spectrometer on Opportunity at Meridiani Planum, identified eight Fe-bearing phases: jarosite (K,Na,H3O