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Sample records for 27al 2h mas

  1. 29Si and 27Al MAS NMR spectra of mullites from different kaolinites.

    PubMed

    He, Hongping; Guo, Jiugao; Zhu, Jianxi; Yuan, Peng; Hu, Cheng

    2004-04-01

    Mullites synthesized from four kaolinites with different random defect densities have been studied by 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) and X-ray diffraction (XRD). All these mullites show the same XRD pattern. However, 29Si and 27Al MAS NMR spectra reveal that the mullites derived from kaolinites with high defect densities, have a sillimanite-type Al/Si ordering scheme and are low in silica, whereas those mullites derived from kaolinites with low defect densities, consist of both sillimanite- and mullite-type Al/Si ordering schemes and are rich in silica. PMID:15084323

  2. Cation disorder determined by MAS {sup 27}Al NMR in high dose neutron irradiated spinel

    SciTech Connect

    Cooper, E.A.; Sickafus, K.E.; Hughes, C.D.; Earl, W.L.; Hollenberg, G.W.; Garner, F.A.; Bradt, R.C.

    1995-12-31

    Spinel (MgAl{sub 2}O{sub 4}) single crystals which had been neutron irradiated to high doses (53-250 dpa) were examined using {sup 27}Al magic angle spinning (MAS) nuclear magnetic resonance (NMR). The sensitivity of this procedure to a specific cation (Al) residing in different crystallographic environments allowed one to determine the distribution of the Al between the two cation sites in the spinel structure. The samples were irradiated at two different temperatures (400 and 750{degrees}C) and various doses. These results indicate that the Al was nearly fully disordered over the two lattice sites after irradiation.

  3. 2H and 27Al Solid-State NMR Study of the Local Environments in Al-Doped 2-Line Ferrihydrite, Goethite, and Lepidocrocite

    PubMed Central

    2015-01-01

    Although substitution of aluminum into iron oxides and oxyhydroxides has been extensively studied, it is difficult to obtain accurate incorporation levels. Assessing the distribution of dopants within these materials has proven especially challenging because bulk analytical techniques cannot typically determine whether dopants are substituted directly into the bulk iron oxide or oxyhydroxide phase or if they form separate, minor phase impurities. These differences have important implications for the chemistry of these iron-containing materials, which are ubiquitous in the environment. In this work, 27Al and 2H NMR experiments are performed on series of Al-substituted goethite, lepidocrocite, and 2-line ferrihydrite in order to develop an NMR method to track Al substitution. The extent of Al substitution into the structural frameworks of each compound is quantified by comparing quantitative 27Al MAS NMR results with those from elemental analysis. Magnetic measurements are performed for the goethite series to compare with NMR measurements. Static 27Al spin–echo mapping experiments are used to probe the local environments around the Al substituents, providing clear evidence that they are incorporated into the bulk iron phases. Predictions of the 2H and 27Al NMR hyperfine contact shifts in Al-doped goethite and lepidocrocite, obtained from a combined first-principles and empirical magnetic scaling approach, give further insight into the distribution of the dopants within these phases. PMID:26321790

  4. {sup 27}Al and {sup 29}Si MAS spectroscopy of layer silicates in Argonne premium coals.

    SciTech Connect

    Thompson, A. R.; Botto, R. E.; Chemistry; DOA

    2001-01-01

    High-resolution {sup 27}Al and {sup 29}Si NMR were employed to characterize layered silicates in the suite of eight Argonne Premium coals. Analyses were performed on native coals directly, or fractions isolated by sink-float techniques. Mineral phases of kaolinite, quartz, and illite-montmorillinite clays could readily be distinguished nonquantitatively by {sup 29}Si NMR techniques using direct detection or cross polarization. {sup 27}Al NMR was used to determine quantitatively the amounts of tetrahedral and octahedral aluminum forms present. The {sup 27}Al NMR results were consistent with mineralogical analyses by XRD, showing that increases in tetrahedral content paralleled illitization of the clay minerals. A remarkably good relationship also was found between the total amount of tetrahedral aluminum associated with the mineral matter and degree of maturation of the organic matter in the coal. The data suggest that illitization of the clays can be used as a mineralogical thermal maturity indicator for Type II kerogens, as demonstrated for the Argonne Premium coals, provided that contributions from organo-chelated aluminum species and detrital mineral matter are taken into account.

  5. Friedel's salt formation in sulfoaluminate cements: A combined XRD and {sup 27}Al MAS NMR study

    SciTech Connect

    Paul, G.; Boccaleri, E.; Buzzi, L.; Canonico, F.; Gastaldi, D.

    2015-01-15

    Four different binders based on calcium sulfoaluminate cements have been submitted to accelerated chlorination through ionic exchange on hydrated pastes, in order to investigate their ability to chemically bind chloride ions that might reduce chloride penetration. The composition of hydrated cements before and after the treatment was evaluated by means of an X-Ray Diffraction–{sup 27}Al Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy combined study, allowing to take into account even partially amorphous phases and to make quantitative assumption on the relative abundance of the different aluminium-containing phases. It was found that low SO{sub 3} Sulfoaluminate–Portland ternary systems are the most effective in binding chloride ions and the active role played by different members of the AFm family in chloride uptake was confirmed. Moreover, a peculiar behavior related to the formation of Friedel's salt in different pH conditions was also established for the different cements.

  6. Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

    SciTech Connect

    Chagas, L.H.; De Carvalho, G.S.G.; San Gil, R.A.S.; Chiaro, S.S.X.; Leitão, A.A.; Diniz, R.

    2014-01-01

    Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrational and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.

  7. Al speciation in tropical podzols of the upper Amazon Basin: A solid-state 27Al MAS and MQMAS NMR study

    NASA Astrophysics Data System (ADS)

    Bardy, Marion; Bonhomme, Christian; Fritsch, Emmanuel; Maquet, Jocelyne; Hajjar, Redouane; Allard, Thierry; Derenne, Sylvie; Calas, Georges

    2007-07-01

    In the upper Amazon Basin, aluminum previously accumulated in lateritic formations is massively remobilised in soils by podzolization and exported in waters. We have investigated the speciation of aluminum in the clay-size fractions of eight horizons of waterlogged podzols lying in a depression of a plateau. The horizons illustrate the main steps involved in the podzolization of laterites. They belong to eluviated topsoil A horizons and illuviated subsoil Bhs, Bh and 2BCs horizons of weakly and better-expressed podzols located at the margin and centre of the depression. For the first time, aluminum speciation is quantitatively assessed in soils by spectroscopic methods, namely FTIR, 27Al magic angle spinning (MAS) and multiple-quantum magic angle spinning (MQMAS), nuclear magnetic resonance (NMR). The results thus obtained are compared to chemical extraction data. Solid-state 27Al MAS NMR spectra enable to distinguish Al bound to organic compounds from that incorporated in secondary mineral phases detected by FTIR. MQMAS experiments additionally show that both chemical shifts and quadrupolar constants are distributed for Al nuclei linked with organic compounds. Similar amounts of chelated Al are obtained from NMR spectra and chemical extractions. The study enables to highlight three major steps in the fate of aluminum. (i) Aluminum is first released by mineral weathering, feeds complexing sites of organic matter and accumulates in subsurface Bhs horizons of weakly expressed podzols (acidocomplexolysis). (ii) Complexes of aluminum with organic matter (Al-OM) then migrate downwards in sandy horizons of better-expressed podzols and accumulate at depth in less permeable 2BCs horizons. (iii) The minor amounts of aluminum present in the 2BCs horizon of the downslope podzol show that aluminum is eventually exported towards the river network, either complexed with organic matter or as Al 3+ ions after desorption from organic compounds, due to decreasing pH or

  8. Study of the A(e,e'$\\pi^+$) Reaction on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au

    SciTech Connect

    Qian, X; Clasie, B; Arrington, J; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Christy, M E; Chudakov, E; Dalton, M M; Daniel, A; Day, D; Dutta, D; El Fassi, L; Ent, R; Fenker, H C; Ferrer, J; Fomin, N; Gao, H; Garrow, K; Gaskell, D; Gray, C; Huber, G M; Jones, M K; Kalantarians, N; Keppel, C E; Kramer, K; Li, Y; Liang, Y; Lung, A F; Malace, S; Markowitz, P; Matsumura, A; Meekins, D G; Mertens, T; Miyoshi, T; Mkrtchyan, H; Monson, R; Navasardyan, T; Niculescu, G; Niculescu, I; Okayasu, Y; Opper, A K; Perdrisat, C; Punjabi, V; Rauf, A W; Rodriquez, V M; Rohe, D; Seely, J; Segbefia, E; Smith, G R; Sumihama, M; Tadevosyan, V; Tang, L; Villano, A; Vulcan, W F; Wesselmann, F R; Wood, S A; Yuan, L; Zheng, X

    2010-05-01

    Cross sections for the p($e,e'\\pi^{+}$)n process on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in order to extract the nuclear transparencies. Data were taken for four-momentum transfers ranging from $Q^2$=1.1 to 4.8 GeV$^2$ for a fixed center of mass energy of $W$=2.14 GeV. The ratio of $\\sigma_L$ and $\\sigma_T$ was extracted from the measured cross sections for $^1$H, $^2$H, $^{12}$C and $^{63}$Cu targets at $Q^2$ = 2.15 and 4.0 GeV$^2$ allowing for additional studies of the reaction mechanism. The experimental setup and the analysis of the data are described in detail including systematic studies needed to obtain the results. The results for the nuclear transparency and the differential cross sections as a function of the pion momentum at the different values of $Q^2$ are presented. Global features of the data are discussed and the data are compared with the results of model calculations for the p($e,e'\\pi^{+}$)n reaction from nuclear targets.

  9. Investigation of multiaxial molecular dynamics by 2H MAS NMR spectroscopy.

    PubMed

    Kristensen, J H; Hoatson, G L; Vold, R L

    1998-11-01

    The technique of 2H MAS NMR spectroscopy is presented for the investigation of multiaxial molecular dynamics. To evaluate the effects of discrete random reorientation a Lie algebraic formalism based on the stochastic Liouville-von Neumann equation is developed. The solution to the stochastic Liouville-von Neumann equation is obtained both in the presence and absence of rf irradiation. This allows effects of molecular dynamics to be evaluated during rf pulses and extends the applicability of the formalism to arbitrary multiple pulse experiments. Theoretical methods are presented for the description of multiaxial dynamics with particular emphasis on the application of vector parameters to represent molecular rotations. Numerical time and powder integration algorithms are presented that are both efficient and easy to implement computationally. The applicability of 2H MAS NMR spectroscopy for investigating molecular dynamics is evaluated from theoretical spectra. To demonstrate the potential of the technique the dynamics of thiourea-2H4 is investigated experimentally. From a series of variable temperature MAS and quadrupole echo spectra it has been found that the dynamics can be described by composite rotation about the CS and CN bonds. Both experiments are sensitive to the fast CS rotation which is shown to be described by the Arrhenius parameters E(CS) = 46.4 +/- 2.3 kJ mol(-1) and ln(A(CS))= 32.6 +/- 0.9. The MAS experiment represents a significant improvement by simultaneously allowing the dynamics of the slow CN rotation to be fully characterized in terms of E(CN) = 56.3 +/- 3.4 kJ mol(-1) and ln(A(CN)) = 25.3 +/- 1.1. PMID:9875600

  10. {sup 13}C chemical shift anisotropies for carbonate ions in cement minerals and the use of {sup 13}C, {sup 27}Al and {sup 29}Si MAS NMR in studies of Portland cement including limestone additions

    SciTech Connect

    Sevelsted, Tine F.; Herfort, Duncan

    2013-10-15

    {sup 13}C isotropic chemical shifts and chemical shift anisotropy parameters have been determined for a number of inorganic carbonates relevant in cement chemistry from slow-speed {sup 13}C MAS or {sup 13}C({sup 1}H) CP/MAS NMR spectra (9.4 T or 14.1 T) for {sup 13}C in natural abundance. The variation in the {sup 13}C chemical shift parameters is relatively small, raising some doubts that different carbonate species in Portland cement-based materials may not be sufficiently resolved in {sup 13}C MAS NMR spectra. However, it is shown that by combining {sup 13}C MAS and {sup 13}C({sup 1}H) CP/MAS NMR carbonate anions in anhydrous and hydrated phases can be distinguished, thereby providing valuable information about the reactivity of limestone in cement blends. This is illustrated for three cement pastes prepared from an ordinary Portland cement, including 0, 16, and 25 wt.% limestone, and following the hydration for up to one year. For these blends {sup 29}Si MAS NMR reveals that the limestone filler accelerates the hydration for alite and also results in a smaller fraction of tetrahedrally coordinated Al incorporated in the C-S-H phase. The latter result is more clearly observed in {sup 27}Al MAS NMR spectra of the cement–limestone blends and suggests that dissolved aluminate species in the cement–limestone blends readily react with carbonate ions from the limestone filler, forming calcium monocarboaluminate hydrate. -- Highlights: •{sup 13}C chemical shift anisotropies for inorganic carbonates from {sup 13}C MAS NMR. •Narrow {sup 13}C NMR chemical shift range (163–171 ppm) for inorganic carbonates. •Anhydrous and hydrated carbonate species by {sup 13}C MAS and {sup 13}C({sup 1}H) CP/MAS NMR. •Limestone accelerates the hydration for alite in Portland – limestone cements. •Limestone reduces the amount of aluminium incorporated in the C-S-H phase.

  11. Molecular dynamics of spider dragline silk fiber investigated by 2H MAS NMR.

    PubMed

    Shi, Xiangyan; Holland, Gregory P; Yarger, Jeffery L

    2015-03-01

    The molecular dynamics of the proteins that comprise spider dragline silk were investigated with solid-state (2)H magic angle spinning (MAS) NMR line shape and spin-lattice relaxation time (T1) analysis. The experiments were performed on (2)H/(13)C/(15)N-enriched N. clavipes dragline silk fibers. The silk protein side-chain and backbone dynamics were probed for Ala-rich regions (β-sheet and 31-helical domains) in both native (dry) and supercontracted (wet) spider silk. In native (dry) silk fibers, the side chains in all Ala containing regions undergo similar fast methyl rotations (>10(9) s(-1)), while the backbone remains essentially static (<10(2) s(-1)). When the silk is wet and supercontracted, the presence of water initiates fast side-chain and backbone motions for a fraction of the β-sheet region and 31-helicies. β-Sheet subregion 1 ascribed to the poly(Ala) core exhibits slower dynamics, while β-sheet subregion 2 present in the interfacial, primarily poly(Gly-Ala) region that links the β-sheets to disordered 31-helical motifs, exhibits faster motions when the silk is supercontracted. Particularly notable is the observation of microsecond backbone motions for β-sheet subregion 2 and 31-helicies. It is proposed that these microsecond backbone motions lead to hydrogen-bond disruption in β-sheet subregion 2 and helps to explain the decrease in silk stiffness when the silk is wet and supercontracted. In addition, water mobilizes and softens 31-helical motifs, contributing to the increased extensibility observed when the silk is in a supercontracted state. The present study provides critical insight into the supercontraction mechanism and corresponding changes in mechanical properties observed for spider dragline silks. PMID:25619304

  12. Carbonation of C–S–H and C–A–S–H samples studied by {sup 13}C, {sup 27}Al and {sup 29}Si MAS NMR spectroscopy

    SciTech Connect

    Sevelsted, Tine F.; Skibsted, Jørgen

    2015-05-15

    Synthesized calcium silicate hydrate (C–S–H) samples with Ca/Si ratios of 0.66, 1.0, and 1.5 have been exposed to atmospheric CO{sub 2} at room temperature and high relative humidity and studied after one to 12 weeks. {sup 29}Si NMR reveals that the decomposition of C–S–H caused by carbonation involves two steps and that the decomposition rate decreases with increasing Ca/Si ratio. The first step is a gradual decalcification of the C–S–H where calcium is removed from the interlayer and defect sites in the silicate chains until Ca/Si = 0.67 is reached, ideally corresponding to infinite silicate chains. In the seconds step, calcium from the principal layers is consumed, resulting in the final decomposition of the C–S–H and the formation of an amorphous silica phase composed of Q{sup 3} and Q{sup 4} silicate tetrahedra. The amount of solid carbonates and of carbonate ions in a hydrous environment increases with increasing Ca/Si ratio for the C–S–H, as shown by {sup 13}C NMR. For C–A–S–H samples with Ca/Si = 1.0 and 1.5, {sup 27}Al NMR demonstrates that all aluminium sites associated with the C–S–H are consumed during the carbonation reactions and incorporated mainly as tetrahedral Al(–OSi){sub 4} units in the amorphous silica phase. A small amount of penta-coordinated Al sites has also been identified in the silica phase.

  13. {sup 27}Al and {sup 23}Na MAS NMR and powder x-ray diffraction studies of sodium aluminate speciation and the mechanistics of aluminum hydroxide precipitation upon acid hydrolysis

    SciTech Connect

    Bradley, S.M.; Hanna, J.V.

    1994-08-24

    {sup 27}Al and {sup 23}Na MAS NMR, powder X-ray diffraction, and infrared spectroscopic investigations of freeze-dried sodium aluminates and aluminum hydroxides formed through acid hydrolysis have been undertaken, with OH/Al hydrolysis ratios between 5.3 and 2.8 being analyzed. Numerous {sup 27}AlNMR resonances were observed, the intensities of which vary as a function of OH/Al ratio, and these have been assigned to four-, five-, and six-coordinate aluminum species constituting a variety of structural moieties. The dominant species at an OH/Al ratio above 4.4 appears to be a Q{sup o}Na[Al(OH);{sub 4}] salt, as indicated by a {sup 27}Al resonance at 86.6 ppm. In addition, a second, broader resonance at 71.3 ppm demonstrates the simultaneous existence of further four-coordinate aluminum species linked thorough oxo bonds to other four-coordinate aluminums (e.g., Q{sup 2} [Al(OH);{sub 2}(OAl){sub 2}];{sup x-}). At an OH/Al ratio between 4.4 and 4.1, a water-soluble phase forms that contains both four- and six-coordinate aluminum. At OH/Al ratios fo 4.0 and below, a water-soluble phase forms that contains both four-and six-coordinate aluminum. AT OH/Al ratios of 4.0 and below, a water-insoluble phase exists possessing four-, five-, and six-coordinate aluminum. At OH/Al{le}3.9 range exhibits {sup 27}Al chemical shifts similar to those reported for transitional aluminas such as {gamma}-, {eta}-, and 0-Al{sub 2}O{sub 3} and an infrared spectrum similar to pseudo-spinel gels, suggesting that a pseudo-spinel intermediate is the first phase involved in the crystallization of gibbsite. The resonance assigned to five-coordinate aluminum probably results from species involved in the transformation of the pseudo-spinal phase to pseudo-boehmite. The formation of gibbssite on the acid hydrolysis of alkaline sodium aluminate solutions thus appears to follow the pathway pseudo-spinel {r_arrow} pseudo-boehmite {r_arrow} bayerite {r_arrow} gibbsite. 82 refs., 7 figs., 3 tabs.

  14. The Local Structural State of Aluminosilicate Garnet Solid Solutions: An Investigation of Grospydite Garnet from the Roberts Victor Kimberlite Using Paramagnetically Shifted 27Al and 29Si MAS NMR Resonances

    NASA Astrophysics Data System (ADS)

    Geiger, C. A.; Palke, A. C.; Stebbins, J. F.

    2014-12-01

    Most rock-forming silicates are substitutional solid solutions. Over the years extensive research has been done to determine their structural and crystal chemical properties. Here, the distribution of cations, or order-disorder behavior, is of central importance. In the case of aluminosilicate garnet solid solutions (X3Al2Si3O12 with X = Mg, Fe2+, Mn2+ and Ca) it has been shown that both synthetic and natural crystals have random long-range X-cation disorder in space group Ia-3d, as given by X-ray single-crystal diffraction measurements. However, the structural state of natural garnets at the local scale is not known. Garnet from a grospydite xenolith from the Roberts Victor kimberlite, South Africa, was studied by 27Al and 29Si MAS NMR spectroscopy. The research thrust was placed on measuring and analyzing paramagnetically shifted resonances to determine the local (short range) structural state of the X-cations in a grossular-rich ternary aluminosilicate garnet solid solution. The garnet crystals are compositionally homogeneous based on microprobe analysis, showing no measurable zoning, and have the formula Grs46.7Prp30.0Alm23.3. The garnet is cubic with the standard garnet space group Ia-3d. The 27Al MAS NMR spectrum shows a very broad asymmetric resonance located between about 100 and -50 ppm. It consists of a number of individual overlapping paramagnetically shifted resonances, which are difficult to analyze quantitatively. The 29Si MAS NMR spectrum, showing better resolution, has two observable resonances termed S0 and S4. S0 is located between about -60 ppm and -160 ppm and S4 is centered at roughly 95 ppm. Both S0 and S4 are composite resonances in nature containing many overlapping individual peaks. S0 contains information on local cation configurations whereby an isolated SiO4 group in the garnet structure does not have an edge-shared Fe2+-containing dodecahedron. S4 involves local configurations where there is one edge-shared dodecahedron containing Fe2

  15. Site-resolved 2H relaxation experiments in solid materials by global line-shape analysis of MAS NMR spectra

    NASA Astrophysics Data System (ADS)

    Lindh, E. L.; Stilbs, P.; Furó, I.

    2016-07-01

    We investigate a way one can achieve good spectral resolution in 2H MAS NMR experiments. The goal is to be able to distinguish between and study sites in various deuterated materials with small chemical shift dispersion. We show that the 2H MAS NMR spectra recorded during a spin-relaxation experiment are amenable to spectral decomposition because of the different evolution of spectral components during the relaxation delay. We verify that the results are robust by global least-square fitting of the spectral series both under the assumption of specific line shapes and without such assumptions (COmponent-REsolved spectroscopy, CORE). In addition, we investigate the reliability of the developed protocol by analyzing spectra simulated with different combinations of spectral parameters. The performance is demonstrated in a model material of deuterated poly(methacrylic acid) that contains two 2H spin populations with similar chemical shifts but different quadrupole splittings. In 2H-exchanged cellulose containing two 2H spin populations with very similar chemical shifts and quadrupole splittings, the method provides new site-selective information about the molecular dynamics.

  16. Site-resolved (2)H relaxation experiments in solid materials by global line-shape analysis of MAS NMR spectra.

    PubMed

    Lindh, E L; Stilbs, P; Furó, I

    2016-07-01

    We investigate a way one can achieve good spectral resolution in (2)H MAS NMR experiments. The goal is to be able to distinguish between and study sites in various deuterated materials with small chemical shift dispersion. We show that the (2)H MAS NMR spectra recorded during a spin-relaxation experiment are amenable to spectral decomposition because of the different evolution of spectral components during the relaxation delay. We verify that the results are robust by global least-square fitting of the spectral series both under the assumption of specific line shapes and without such assumptions (COmponent-REsolved spectroscopy, CORE). In addition, we investigate the reliability of the developed protocol by analyzing spectra simulated with different combinations of spectral parameters. The performance is demonstrated in a model material of deuterated poly(methacrylic acid) that contains two (2)H spin populations with similar chemical shifts but different quadrupole splittings. In (2)H-exchanged cellulose containing two (2)H spin populations with very similar chemical shifts and quadrupole splittings, the method provides new site-selective information about the molecular dynamics. PMID:27152833

  17. Direct Observation of Lattice Aluminum Environments in Li Ion Cathodes LiNi1-y-zCoyAlzO2 and Al-Doped LiNixMnyCozO2 via (27)Al MAS NMR Spectroscopy.

    PubMed

    Dogan, Fulya; Vaughey, John T; Iddir, Hakim; Key, Baris

    2016-07-01

    Direct observations of local lattice aluminum environments have been a major challenge for aluminum-bearing Li ion battery materials, such as LiNi1-y-zCoyAlzO2 (NCA) and aluminum-doped LiNixMnyCozO2 (NMC). (27)Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is the only structural probe currently available that can qualitatively and quantitatively characterize lattice and nonlattice (i.e., surface, coatings, segregation, secondary phase etc.) aluminum coordination and provide information that helps discern its effect in the lattice. In the present study, we use NMR to gain new insights into transition metal (TM)-O-Al coordination and evolution of lattice aluminum sites upon cycling. With the aid of first-principles DFT calculations, we show direct evidence of lattice Al sites, nonpreferential Ni/Co-O-Al ordering in NCA, and the lack of bulk lattice aluminum in aluminum-"doped" NMC. Aluminum coordination of the paramagnetic (lattice) and diamagnetic (nonlattice) nature is investigated for Al-doped NMC and NCA. For the latter, the evolution of the lattice site(s) upon cycling is also studied. A clear reordering of lattice aluminum environments due to nickel migration is observed in NCA upon extended cycling. PMID:27299505

  18. Hydration properties of regioselectively etherified celluloses monitored by 2H and 13C solid-state MAS NMR spectroscopy.

    PubMed

    Larsen, Flemming H; Schöbitz, Michael; Schaller, Jens

    2012-06-20

    The hydration properties of 2,3-O-hydroxypropylcellulose (HPC) and 2,3-O-hydroxyethylcellulose (HEC) were analyzed by multi-nuclear solid-state MAS NMR spectroscopy. By 13C single-pulse (SP) MAS and cross-polarization (CP) MAS NMR, differences between the immobile regions and all parts of the polysaccharides were detected as a function of hydration. Complementary information about the water environments was observed by 2H MAS NMR. By this approach it was demonstrated that side chains in 2,3-O-HPC and 2,3-O-HEC were easier to hydrate than the cellulose backbone. Furthermore the motion of water was more restricted (slower) in 2,3-O-HPC than in 2,3-O-HEC. For both polysaccharides the hydration could be explained by a two-step process: in step one increased ordering of the immobile regions occurs after which the entire polymer is hydrated in step two. PMID:24750769

  19. Nonstatistical fluctuations for deep inelastic processes in {sup 27}Al+{sup 27}Al collisions

    SciTech Connect

    Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Pop, A.; Simion, V.; Zoppo, A. Del; D'Erasmo, G.; Imme, G.; Lanzano, G.; Pagano, A.; Pantaleo, A.; Raciti, G.

    2006-08-15

    The excitation functions (EFs) for different fragments produced in the {sup 27}Al+{sup 27}Al dissipative collisions have been measured in steps of 250 keV in the incident energy range 122-132 MeV. Deep inelastic processes have been selected by integrating events on a total kinetic energy loss window of 12 MeV between 20 and 32 MeV. Large fluctuations are observed in all the studied EFs. Large-channel cross-correlation coefficients confirm the nonstatistical origin of these fluctuations. The energy autocorrelation function (EAF) shows damped oscillation structure as expected when a dinuclear system with a lifetime [{tau}=(5.1{+-}2.1){center_dot}10{sup -21}s], similar with its revolution period (T=4.9{center_dot}10{sup -21}sec), is formed. From the periodicity of the EAF oscillations, information on the deformation of the {sup 27}Al+{sup 27}Al dinucleus is inferred.

  20. Complete fusion of 15N+27Al

    NASA Astrophysics Data System (ADS)

    Prosser, F. W., Jr.; Racca, R. A.; Daneshvar, K.; Geesaman, D. F.; Henning, W.; Kovar, D. G.; Rehm, K. E.; Tabor, S. L.

    1980-05-01

    The total fusion cross section for the system 15N + 27Al has been measured over an energy range 27 MeV<=Elab<=70 MeV by detection of the fusion-evaporation residues. In addition elastic scattering was measured at six energies and fitted by optical model calculations. The fusion cross section for the system saturates at 1150+/-50 mb. The data can be well described by the model of Glas and Mosel, using a reasonable set of parameters. The model of Horn and Ferguson also describes the data well if an appropriate charge radius is used. Comparison is made between these results and the fusion cross sections for 16O + 26Mg and 18O + 24Mg, which lead to the same compound nucleus. The results for 15N + 27Al are quite similar to those for 18O + 24Mg, and the differences between the fusion cross sections for these two systems and those for 16O + 26Mg may be evidence for an entrance channel effect. NUCLEAR REACTIONS 15N+27Al, Elab=27-70 MeV; measured σfusion(E) measured dσdΩ elastic scattering; data fitted with Glas and Mosel model, Horn and Ferguson model.

  1. Characterization of Al30 in commercial poly-aluminum chlorohydrate by solid-state (27)Al NMR spectroscopy.

    PubMed

    Phillips, Brian L; Vaughn, John S; Smart, Scott; Pan, Long

    2016-08-15

    Investigation of commercially produced hydrolysis salts of aluminum by solid-state (27)Al NMR spectroscopy and size-exclusion chromatography (SEC) reveals well-defined and distinct Al environments that can be related to physicochemical properties. (27)Al MAS and MQ-MAS NMR spectroscopic data show that the local structure of the solids is dominated by moieties that closely resemble the Al30 polyoxocation (Al30O8(OH)56(H2O)26(18+)), accounting for 72-85% of the total Al. These Al30-like clusters elute as several size fractions by SEC. Comparison of the SEC and NMR results indicates that the Al30-like clusters includes intact isolated clusters, moieties of larger polymers or aggregates, and possibly fragments resembling δ-Al13 Keggin clusters. The coagulation efficacy of the solids appears to correlate best with the abundance of intact Al30-like clusters and of smaller species available to promote condensation reactions. PMID:27232539

  2. Studies of 27Al NMR in SrAl4

    NASA Astrophysics Data System (ADS)

    Niki, Haruo; Higa, Nonoka; Kuroshima, Hiroko; Toji, Tatsuki; Morishima, Mach; Minei, Motofumi; Yogi, Mamoru; Nakamura, Ai; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika; Harima, Hisatomo

    A charge density wave (CDW) transition at TCDW = 243 K and a structural phase (SP) transition at approximately 100 K occur in SrAl4 with the BaAl4-type body center tetragonal structure, which is the divalent and non-4f electron reference compound of EuAl4. To understand the behaviors of the CDW and SP transitions, the 27Al NMR measurements using a single crystal and a powder sample of SrAl4 have been carried out. The line width below TCDW is modulated by an electrical quadruple interaction between 27Al nucleus and CDW charge modulation. The incommensurate CDW state below TCDW changes into a different structure below TSP. The temperature dependences of Knight shifts of 27Al(I) and 27Al(II) show the different behaviors. The temperature variation of 27Al(I) Knight shift shows anomalies at the CDW and SP transition temperatures, revealing the shift to negative side below TCDW, which is attributable to the core polarization of the d-electrons. However, 27Al(II) Knight shift keeps almost constant except for the small shift due to the SP transition. The 1/T1T of 27Al(I) indicates the obvious changes due to the CDW and SP transitions, while that of 27Al(II) takes a constant value. The density of state at the Fermi level at Al(I) site below 60 K would be about 0.9 times less than that above TCDW.

  3. 27Al and 29Si solid-state NMR characterization of calcium-aluminosilicate-hydrate.

    PubMed

    Pardal, Xiaolin; Brunet, Francine; Charpentier, Thibault; Pochard, Isabelle; Nonat, André

    2012-02-01

    Calcium silicate hydrate (C-S-H) is the main constituent of hydrated cement paste and determines its cohesive properties. Because of the environmental impact of cement industry, it is more and more common to replace a part of the clinker in cement by secondary cementitious materials (SCMs). These SCMs are generally alumina-rich and as a consequence some aluminum is incorporated into the C-S-H. This may have consequences on the cohesion and durability of the material, and it is thus of importance to know the amount and the location of Al in C-S-H and what the parameters are that control these features. The present paper reports the (29)Si and (27)Al MAS NMR analyses of well-characterized C-A-S-H samples (C-S-H containing Al). These samples were synthesized using an original procedure that successfully leads to pure C-A-S-H of controlled compositions in equilibrium with well-characterized solutions. The (27)Al MAS NMR spectra were quantitatively interpreted assuming a tobermorite-like structure for C-A-S-H to determine the aluminum location in this structure. For this purpose, an in-house written software was used which allows decomposing several spectra simultaneously using the same constrained spectral parameters for each resonance but with variable intensities. The hypothesis on the aluminum location in the C-A-S-H structure determines the proportion of each silicon site. Therefore, from the (27)Al NMR quantitative results and the chemical composition of each sample, the intensity of each resonance line in the (29)Si spectra was set. The agreement between the experimental and calculated (29)Si MAS NMR spectra corroborates the assumed C-A-S-H structure and the proposed Al incorporation mechanism. The consistency between the results obtained for all compositions provides another means to assess the assumptions on the C-A-S-H structure. It is found that Al substitutes Si mainly in bridging positions and moderately in pairing positions in some conditions. Al in

  4. Barrier distributions for the 7Li+27Al reaction

    NASA Astrophysics Data System (ADS)

    Cárdenas, W. H. Z.

    2010-08-01

    Barrier distributions can be obtained from the first derivative of the elastic and quasielastic (QEL) backward angle excitation functions [1]. In this work we present a study of the barrier distribution for the 7Li+27Al reaction from a Coupled-Channels Born Approximation (CCBA) calculations using the code FRESCO [2].

  5. Solid-state 27Al and 29Si NMR characterization of hydrates formed in calcium aluminate silica fume mixtures

    NASA Astrophysics Data System (ADS)

    Pena, P.; Rivas Mercury, J. M.; de Aza, A. H.; Turrillas, X.; Sobrados, I.; Sanz, J.

    2008-08-01

    Partially deuterated Ca 3Al 2(SiO 4) y(OH) 12-4y-Al(OH) 3 mixtures, prepared by hydration of Ca 3Al 2O 6 (C 3A), Ca 12Al 14O 33 (C 12A 7) and CaAl 2O 4 (CA) phases in the presence of silica fume, have been characterized by 29Si and 27Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca 3Al 2(OH) 12 and Al(OH) 3 phases were detected. From the quantitative analysis of 27Al NMR signals, the Al(OH) 3/Ca 3Al 2(OH) 12 ratio was deduced. The incorporation of Si into the katoite structure, Ca 3Al 2(SiO 4) 3-x(OH) 4x, was followed by 27Al and 29Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of 27Al MAS-NMR components associated with Al(OH) 6 and Al(OSi)(OH) 5 environments. The 29Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From 29Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures.

  6. Studies of 27Al NMR in EuAl4

    NASA Astrophysics Data System (ADS)

    Niki, H.; Nakamura, S.; Higa, N.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; Ōnuki, Y.; Harima, H.

    2015-03-01

    EuAl4 orders antiferromagnetically at TN ≈ 16 K with an effective magnetic moment of 8.02 μB. In the paramagnetic phase, the magnetic susceptibility of EuAl4 follows the Curie-Weiss law with a positive Curie-Weiss temperature θP = +14 K. The antiferromagnetic state is changed into the field induced ferromagnetic state at a critical field Hc of approximately 2 T. In order to microscopically investigate the magnetic and electronic properties in EuAl4, the NMR measurements of EuAl4 have been carried out at temperatures between 2 and 300 K, applying an external magnetic field of approximately 6.5 T. The 27Al NMR spectra corresponding to Al(I) and Al(II) sites are obtained. From the 27Al NMR spectra, the isotropic part Kiso and anisotropic part Kaniso of Knight shift, and nuclear quadrupole frequncy νQ are obtained. The Kiso and Kaniso shift to negative side with decreasing temperature due to the RKKY interaction. These temperature dependences follow the Curie-Weiss law with θP = +14 K, which is consistent with that of the magnetic susceptibility. From the K - χ plot, the values of the hyperfine fields Hhf_iso and Hhf_aniso are -3.231 and -0.162 kOe/μB for Al(I) site, and -1.823 and -0.264 kOe/μB for Al(II) site, respectively. The values of νQ of 27Al nucleus for Al(I) and Al(II) sites are approximately 0.865 and 0.409 MHz, respectively. The nuclear relaxation time T1 of 27Al NMR for both sites is almost constant in the paramagnetic phase, while the value of 1/T1 is abruptly decreased in the ordered ferromagnetic state.

  7. The NIST 27 Al+ quantum-logic clock

    NASA Astrophysics Data System (ADS)

    Leibrandt, David; Brewer, Samuel; Chen, Jwo-Sy; Hume, David; Hankin, Aaron; Huang, Yao; Chou, Chin-Wen; Rosenband, Till; Wineland, David

    2016-05-01

    Optical atomic clocks based on quantum-logic spectroscopy of the 1 S0 <--> 3 P0 transition in 27 Al+ have reached a systematic fractional frequency uncertainty of 8 . 0 ×10-18 , enabling table-top tests of fundamental physics as well as measurements of gravitational potential differences. Currently, the largest limitations to the accuracy are second order time dilation shifts due to the driven motion (i.e., micromotion) and thermal motion of the trapped ions. In order to suppress these shifts, we have designed and built new ion traps based on gold-plated, laser-machined diamond wafers with differential RF drive, and we have operated one of our clocks with the ions laser cooled to near the six mode motional ground state. We present a characterization of the time dilation shifts in the new traps with uncertainties near 1 ×10-18 . Furthermore, we describe a new protocol for clock comparison measurements based on synchronous probing of the two clocks using phase-locked local oscillators, which allows for probe times longer than the laser coherence time and avoids the Dick effect. This work is supported by ARO, DARPA, and ONR.

  8. Identification of tetrahedrally ordered Si-O-Al environments in molecular sieves by { 27Al}- 29Si REAPDOR NMR

    NASA Astrophysics Data System (ADS)

    Ganapathy, S.; Kumar, Rajiv; Montouillout, V.; Fernandez, C.; Amoureux, J. P.

    2004-05-01

    The silicon sites tetrahedrally connected to aluminum in framework positions of a molecular sieve may be identified by a selective reintroduction of the hetero-nuclear 27Al- 29Si dipolar interaction through Rotational Echo Adiabatic Passage DOuble Resonance (REAPDOR) NMR. In this rotor synchronized 29Si MAS experiment, an effective dipolar dephasing of the Si-O-Al, over Si-O-Si, environments is shown to aid in the identification of silicon sites in the immediate vicinity of aluminum. Application of the method in the structurally interesting and novel molecular sieve ETAS-10 provides valuable insights on the details of aluminum substitution in the zeolite lattice and further leads to the first direct NMR estimate of Al-Si distance ( rAl-Si=323±5 pm) in ETAS-10.

  9. Structure of hydrous aluminosilicate glasses along the diopside anorthite join: A comprehensive one- and two-dimensional 1H and 27Al NMR study

    NASA Astrophysics Data System (ADS)

    Xue, Xianyu; Kanzaki, Masami

    2008-05-01

    We have taken a systematic approach utilizing advanced solid-state NMR techniques to gain new insights into the controversial issue concerning the dissolution mechanisms of water in aluminosilicate melts (glasses). A series of quenched anhydrous and hydrous (˜2 wt% H 2O) glass samples along the diopside (Di, CaMgSi 2O 6)—anorthite (An, CaAl 2Si 2O 8) join with varying An components (0, 20, 38, 60, 80, and 100 mol %) have been studied. A variety of NMR techniques, including one-dimensional (1D) 1H and 27Al MAS NMR, and 27Al → 1H cross-polarization (CP) MAS NMR, as well as two-dimensional (2D) 1H double-quantum (DQ) MAS NMR, 27Al triple-quantum (3Q) MAS NMR, and 27Al → 1H heteronuclear correlation NMR (HETCOR) and 3QMAS/HETCOR NMR, have been applied. These data revealed the presence of SiOH, free OH ((Ca,Mg)OH) and AlOH species in the hydrous glasses, with the last mostly interconnected with Si and residing in the more polymerized parts of the structure. Thus, there are no fundamental differences in water dissolution mechanisms for Al-free and Al-bearing silicate melts (glasses), both involving two competing processes: the formation of SiOH/AlOH that is accompanied by the depolymerization of the network structure, and the formation of free OH that has an opposite effect. The latter is more important for depolymerized compositions corresponding to mafic and ultramafic magmas. Aluminum is dominantly present in four coordination (Al IV), but a small amount of five-coordinate Al (Al V) is also observed in all the anhydrous and hydrous glasses. Furthermore, six-coordinate Al (Al VI) is also present in most of the hydrous glasses. As Al of higher coordinations are favored by high pressure, Al VIOH and Al VOH may become major water species at higher pressures corresponding to those of the Earth's mantle.

  10. Elastic scattering and total reaction cross section for the 6He + 27Al system

    NASA Astrophysics Data System (ADS)

    Benjamim, E. A.; Lépine-Szily, A.; Mendes Junior, D. R.; Lichtenthäler, R.; Guimarães, V.; Gomes, P. R. S.; Chamon, L. C.; Hussein, M. S.; Moro, A. M.; Arazi, A.; Padron, I.; Alcantara Nuñez, J.; Assunção, M.; Barioni, A.; Camargo, O.; Denke, R. Z.; de Faria, P. N.; Pires, K. C. C.

    2007-03-01

    The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier using the RIBRAS (Radioactive Ion Beams in Brazil) facility. The São Paulo Potential (SPP) was used and its diffuseness and imaginary strength were adjusted to fit the elastic scattering angular distributions. Reaction cross-sections were extracted from the optical model fits. The reduced reaction cross-sections of 6He on 27Al are similar to those for stable, weakly bound projectiles as 6,7Li, 9Be and larger than stable, tightly bound projectile as 16O on 27Al.

  11. Application of solids MAS nuclear magnetic resonance to study of diagenetic processes

    SciTech Connect

    Sommer, S.E.; Woessner, D.E.

    1984-04-01

    Magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR) provides the opportunity to probe composition of and ordering in minerals involved in the formation and alteration of sediments. MAS-NMR has the capability to detect a large number of elements, including aluminum, silicon, boron, oxygen, and magnesium. The chemical state, structural location, and with cross polarization, hydration character and surface proximity can also be determined using this method. Although MAS-NMR is relatively new and quantitative methodology is still being developed, a variety of geologic processes have been clarified through its application. Use of /sup 27/Al NMR allows detailed determination of the smectite-illite transformation by monitoring the movements of aluminum into tetrahedral positions and resultant cation ordering. Because /sup 27/Al is detectable to low ppm levels, clay mineral components can be determined well below XRD detection levels. The /sup 29/Si and /sup 27/Al MAS-NMR have sufficient resolution to discriminate between minerals in a natural assemblage but not with the resolution of XRD. Quadrupolar nuclei such as /sup 27/Al have relatively poor spectral resolution as compared to nonquadrupolar nuclei such as /sup 29/Si. However, modern high field instrumentation can discriminate between most aluminum-containing minerals including aluminum oxides, hydroxides, oxyhydroxides, clays, and feldspars, as well as trace aluminum levels in quartz, cristobalite, and tridymite. The combination of /sup 27/Al and /sup 29/Si NMR (and availability of other nuclei) provide a powerful aid to the resolution of exploration and production problems including determination of minor to trace amorphous components, hydration state of elements in cherts and clays, and formation damage.

  12. Differential cross section measurements of 27Al(p,p/γ)27Al and 27Al(p,αγ)24Mg reactions in the energy range of 1.6-3.0 MeV

    NASA Astrophysics Data System (ADS)

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.; Sharifzadeh, N.; Fathollahi, V.

    2015-11-01

    In this work measurement of differential cross sections of 27Al(p,p/γ)27Al (Eγ = 844, 1014 keV) and 27Al(p,αγ)24Mg (Eγ = 1369 keV) nuclear reactions in the proton energy range of 1.6-3.0 MeV are described and the measured values are presented. Thin Al target was prepared by evaporating a 26 μg/cm2 Al onto a 129 μg/cm2 self-supporting Ag film. The gamma-rays and backscattered protons were detected simultaneously. The gamma-rays and protons were collected by an HPGe detector placed at an angle of 90° with respect to beam direction and an ion implanted Si detector placed at a scattering angle of 165°, respectively. In this experimental setup the great advantage is that differential cross sections could be independent on absolute values of the collected beam charge. The overall systematic uncertainty of cross sections was estimated to be ±9% while statistical errors were less than ±5%.

  13. 27Al and 1H Solid State NMR Studies Show Evidence of TiAl3 and TiH2 in Ti-doped NaAlH4

    SciTech Connect

    Herberg, J; Maxwell, R; Majzoub, E

    2005-05-26

    Previous X-ray Diffraction (XRD) and Nuclear Magnetic Resonance (NMR) studies on Ti-doped NaAlH{sub 4} revealed the reaction products of two heavily doped (33.3 at.%) samples that were solvent-mixed and mechanically-milled. This investigation revealed that nano-crystalline or amorphous Al{sub 2}O{sub 3} forms from the possible coordination of aluminum with oxygen atom of the furan ring system from added tetrahydrofuran (THF) in the solvent-mixed sample, and that TiAl{sub 3} forms in mechanically-milled samples. The present paper provides a more sophisticated NMR investigation of the these materials. On heavily doped (33.3 at.%) solvent-mixed samples, {sup 27}Al Magic Angle Spinning (MAS) NMR {sup 27}Al multiple quantum MAS (MQMAS) indicates the presence of an oxide layer of Al{sub 2}O{sub 3} on the surfaces of potentially bulk nanocrystalline Ti, nanocrystalline TiAl{sub 3}, and/or metallic aluminum. The {sup 1}H MAS NMR data also indicate the possible coordination of aluminum with the oxygen atom in the THF. On heavily doped samples that were mechanically milled, {sup 27}Al MAS NMR and static NMR confirms the presence of TiAl{sub 3}. In addition, the {sup 1}H MAS NMR and {sup 1}H spin-lattice relaxation (T{sub 1}) measurements are consistent with the presence of TiH{sub 2}. These results are in agreement with recent XAFS measurements indicating both Al and H within the first few coordination shells of Ti in the doped alanate.

  14. Solid-state {sup 27}Al and {sup 29}Si NMR characterization of hydrates formed in calcium aluminate-silica fume mixtures

    SciTech Connect

    Pena, P.; Rivas Mercury, J.M.

    2008-08-15

    Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub y}(OH){sub 12-4y}-Al(OH){sub 3} mixtures, prepared by hydration of Ca{sub 3}Al{sub 2}O{sub 6} (C{sub 3}A), Ca{sub 12}Al{sub 14}O{sub 33} (C{sub 12}A{sub 7}) and CaAl{sub 2}O{sub 4} (CA) phases in the presence of silica fume, have been characterized by {sup 29}Si and {sup 27}Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca{sub 3}Al{sub 2}(OH){sub 12} and Al(OH){sub 3} phases were detected. From the quantitative analysis of {sup 27}Al NMR signals, the Al(OH){sub 3}/Ca{sub 3}Al{sub 2}(OH){sub 12} ratio was deduced. The incorporation of Si into the katoite structure, Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x}, was followed by {sup 27}Al and {sup 29}Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of {sup 27}Al MAS-NMR components associated with Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The {sup 29}Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From {sup 29}Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures. - Graphical abstract: Transmission electron micrograph of CaAl{sub 2}O{sub 4}-microsilica mixture hydrated at 90 deg. C for 31 days showing a cubic Ca{sub 3}Al{sub 2.0{+-}}{sub 0.2}(SiO{sub 4}){sub 0.9{+-}}{sub 0.2}(OH){sub 1.8} crystal surrounded by unreacted amorphous silica spheres.

  15. Low and medium energy deuteron-induced reactions on {sup 27}Al

    SciTech Connect

    Bem, P.; Simeckova, E.; Honusek, M.; Fischer, U.; Simakov, S. P.; Forrest, R. A.; Avrigeanu, M.; Obreja, A. C.; Roman, F. L.; Avrigeanu, V.

    2009-04-15

    The activation cross sections of (d,p), (d,2p), and (d,p{alpha}) reactions on {sup 27}Al were measured in the energy range from 4 to 20 MeV using the stacked-foils technique. Following a previous extended analysis of elastic scattering, breakup, and direct reaction of deuterons on {sup 27}Al, for energies from 3 to 60 MeV, the preequilibrium and statistical emissions are considered in the same energy range. Finally, all deuteron-induced reactions on {sup 27}Al including the present data measured up to 20 MeV deuteron energy are properly described due to a simultaneous analysis of the elastic scattering and reaction data.

  16. Ferromagnetic ordering in NpAl2: Magnetic susceptibility and 27Al nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Martel, L.; Griveau, J.-C.; Eloirdi, R.; Selfslag, C.; Colineau, E.; Caciuffo, R.

    2015-08-01

    We report on the magnetic properties of the neptunium based ferromagnetic compound NpAl2. We used magnetization measurements and 27Al NMR spectroscopy to access magnetic features related to the paramagnetic and ordered states (TC=56 K). While very precise DC SQUID magnetization measurements confirm ferromagnetic ordering, they show a relatively small hysteresis loop at 5 K reduced with a coercive field HCo~3000 Oe. The variable offset cumulative spectra (VOCS) acquired in the paramagnetic state show a high sensitivity of the 27Al nuclei spectral parameters (Knight shifts and line broadening) to the ferromagnetic ordering, even at room temperature.

  17. Barrier distributions for the {sup 7}Li+{sup 27}Al reaction

    SciTech Connect

    Cardenas, W. H. Z.

    2010-08-04

    Barrier distributions can be obtained from the first derivative of the elastic and quasielastic (QEL) backward angle excitation functions [1]. In this work we present a study of the barrier distribution for the {sup 7}Li+{sup 27}Al reaction from a Coupled-Channels Born Approximation (CCBA) calculations using the code FRESCO [2].

  18. Projectile and Target Fragmentation in the Interaction of 12C and 27Al

    SciTech Connect

    Foertsch, S.V.; Steyn, G.F.; Lawrie, J.J.; Smit, F.D.; Cerutti, F.; Colleoni, P.; Gadioli, E.; Mairani, A.; Connell, S.H.; Fearick, R.W.; Thovhogi, T.; Machner, H.; Goldenbaum, F.; Pysz, K.

    2005-05-24

    The emission of intermediate mass fragments (IMFs) produced in the inclusive 12C+27Al and 27Al+12C reactions at incident energies corresponding to a c.m. excitation energy of 107.5 MeV were studied at lab. angles of 12 deg. to 25 deg. Double differential cross sections of the IMF spectra are compared to model calculations, which include direct breakup of both the projectile and target, nucleon coalescence, as well as partial and complete fusion. This study indicates the importance of the complementary nature of a reaction together with its inverse process in fully understanding the driving reaction mechanisms in the interaction of two light-mass nuclei.

  19. Elastic scattering measurements for {sup 7}Be+{sup 27}Al system at RIBRAS facility

    SciTech Connect

    Morcelle, V.; Lichtenthaeler, R.; Morais, M. C.; Lepine-Szily, A.; Guimaraes, V.; Faria, P. N. de; Gasques, L.; Pires, K. C. C.; Condori, R. P.; Gomes, P. R. S.; Lubian, J.; Mendes, D. R. Jr.; Barioni, A.; Shorto, J. M. B.; Zamora, J. C.

    2013-05-06

    Elastic scattering angular distribution measurements of {sup 7}Be+{sup 27}Al system were performed at the laboratory energy of 15.6 MeV. The {sup 7}Be secondary beam was produced by the proton transfer reaction {sup 3}He({sup 6}Li,{sup 7}Be) and impinged on {sup 27}Al and {sup 197}Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS. The elastic angular distribution was obtained within the angular range of 15{sup 0} - 80{sup 0} at the center of mass frame. Optical model calculations have been performed using the Woods- Saxon form factors and the Sao Paulo potential to fit the experimental data. The total reaction cross section was derived.

  20. Excited states of 26Al studied via the reaction 27Al(d,t)

    NASA Astrophysics Data System (ADS)

    Srivastava, Vishal; Bhattacharya, C.; Rana, T. K.; Manna, S.; Kundu, S.; Bhattacharya, S.; Banerjee, K.; Roy, P.; Pandey, R.; Mukherjee, G.; Ghosh, T. K.; Meena, J. K.; Roy, T.; Chaudhuri, A.; Sinha, M.; Saha, A. K.; Asgar, Md. A.; Dey, A.; Roy, Subinit; Moin Shaikh, Md.

    2016-05-01

    The reaction 27Al(d,t) at 25 MeV was utilized to study the excited states of 26Al. The angular distributions of the observed excited states of 26Al were analyzed with zero range distorted wave Born approximation as well as by incorporating finite range correction parameters to extract spectroscopic factors. The two sets of extracted spectroscopic factors were compared with each other to see the effect of using finite range correction in the transfer form factor.

  1. Electromagnetic dissociation of relativistic sup 28 Si into p + sup 27 Al

    SciTech Connect

    Barrette, J.; Bellwied, R.; Braun-Munzinger, P.; Cleland, W.E.; David, G.; Dee, J.; Dietzsch, O.; Duek, E.; Fatyga, M.; Fox, D.; Greene, S.V.; Hall, J.R.; Hemmick, T.K.; Herrmann, N.; Hogue, R.W.; Hong, B.; Jayananda, K.; Kraus, D.; Shiva Kumar, B.; Lacasse, R.; Lissauer, D.; Llope, W.J.; Ludlam, T.; Majka, R.; Makowiecki, D.; Mark, S.K.; McCorkle, S.; Mitchell, J.T.; Muthuswamy, M.; O'Brien, E.; Polychronakos, V.; Pruneau, C.; Rotondo, F.S.; Sandweiss, J.; Simon-Gillo, J.; Sonnadara, U.; Stachel, J.; Takai, H.; Takagui, E.M.; Throwe, T.G.; Waters, L.; Willis, W.J.; Winter, C.; Wolf, K.; Wolfe, D.; Woody, C.L.; Xu, N.; Zhang, Y.; Zhang, Z.; Zou, Z. European Organization for Nuclear Research , Geneva Los Alamos National Laboratory, Los Alamos, New Mexico 87545 McGill University, Montreal, Quebec, H3A 2K6 University of New Mexico, Albuquerque, New Mexico 87131

    1992-05-01

    We report a direct measurement of the final-state energy spectrum in the electromagnetic dissociation of {sup 28}Si into {ital p}+ {sup 27}Al at an energy of 14.6 GeV/nucleon. The final-state energy is obtained through a calculation of the {ital p}-{sup 27}Al invariant mass in kinematically reconstructed events. The final-state energy spectrum for all targets is peaked near the isovector giant-dipole resonance in {sup 28}Si and the dependence of the magnitude of the cross section on target charge confirms that the excitation is largely electromagnetic. By exploiting the expected scaling behavior on target {ital Z} and {ital A}, the background from nuclear interactions is evaluated and subtracted, leaving a pure electromagnetic dissociation final-state energy distribution. This distribution is well reproduced by simulated events, in which the photon spectrum calculated in the Weiszaecker-Williams approximation is combined with experimental data on the photonuclear reaction {sup 28}Si({gamma},{ital p}) {sup 27}Al, and slight differences are observed only at low final-state energy.

  2. Lead exchange into zeolite and clay minerals: A [sup 29]Si, [sub 27]Al, [sup 23]Na solid-state NMR study

    SciTech Connect

    Liang, J.J.; Sherriff, B.L. )

    1993-08-01

    Chabazite, vermiculite, montmorillonite, hectorite, and kaolinite were used to remove Pb, through ion exchange, from 0.01 M aqueous Pb(NO[sub 3])[sub 2] solutions. These minerals contained 27 (Na-chabazite), 16, 9, 9, and 0.5 wt % of Pb, respectively, after equilibration with the solutions. Ion exchange reached equilibrium within 24 h for Na-chabazite and vermiculite, but in less than 5 min for montmorillonite and hectorite. Na-chabazite took up more Pb than natural (Ca, Na)-chabazite (7 wt % Pb), whereas no such difference was observed in different cation forms of the clay minerals. Calcite impurities, associated with the clay minerals, effectively removed Pb from the aqueous solutions by the precipitation of cerussite (PbCO[sub 3]). [sup 29]Si, [sup 27]Al, and [sup 23]Na magic angle spinning (MAS) nuclear magnetic resonance (NMR), [sup 23]Na double rotation (DOR) NMR, and [sup 23]Na variable-temperature MAS NMR were used to study the ion exchange mechanisms. In Na-chabazite, cations in all three possible sites take part in the fast chemical exchange. The chemical exchange passes from the fast exchange regime to the slow regime at [minus]80 to [minus]100[degrees]C. One site contains a relatively low population of exchangeable cations. The other two more shielded sites contain most of the exchangeable cation. The exchangeable cations in chabazite and vermiculite were found to be close to the SiO[sub 4] and AlO[sub 4] tetrahedra, while those in the other clay minerals were more distant. Two sites (or groups of sites) for exchangeable cations were observed in hectorite. Lead tended to occupy the one which corresponds to the [minus]8 ppM peak on the [sup 23]Na MAS NMR spectrum. The behavior of the exchangeable cations in the interlayer sites was similar in all the clay minerals studied. 27 refs., 7 figs., 4 tabs.

  3. Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al

    SciTech Connect

    Figueira, J. M.; Niello, J. O. Fernandez; Abriola, D.; Arazi, A.; Capurro, O. A.; Barbara, E. de; Marti, G. V.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Padron, I.; Gomes, P. R. S.; Lubian, J.; Correa, T.; Paes, B.

    2007-01-15

    Elastic scattering of the weakly bound {sup 6}Li on {sup 27}Al was measured at near-barrier energies. The data analysis was performed using a Woods-Saxon shape optical potential and also using the double-folding Sao Paulo potential. The results show the presence of the breakup threshold anomaly (BTA), an anomalous behavior when compared with the scattering of tightly bound nuclei. This behavior is attributed to a repulsive polarization potential produced by the coupling to the continuum breakup states.

  4. Supra-canonical 26Al/27Al and the residence time of CAIs in the solar protoplanetary disk.

    PubMed

    Young, Edward D; Simon, Justin I; Galy, Albert; Russell, Sara S; Tonui, Eric; Lovera, Oscar

    2005-04-01

    The canonical initial 26Al/27Al ratio of 4.5 x 10(-5) has been a fiducial marker for the beginning of the solar system. Laser ablation and whole-rock multiple-collector inductively coupled plasma-source mass spectrometry magnesium isotope analyses of calcium- and aluminum-rich inclusions (CAIs) from CV3 meteorites demonstrate that some CAIs had initial 26Al/27Al values at least 25% greater than canonical and that the canonical initial 26Al/27Al cannot mark the beginning of solar system formation. Using rates of Mg diffusion in minerals, we find that the canonical initial 26Al/27Al is instead the culmination of thousands of brief high-temperature events incurred by CAIs during a 10(5)-year residence time in the solar protoplanetary disk. PMID:15746387

  5. Fine structure of the isoscalar giant quadrupole resonance in 28Si and 27Al

    NASA Astrophysics Data System (ADS)

    Usman, I. T.; Buthelezi, Z.; Carter, J.; Cooper, G. R. J.; Fearick, R. W.; Förtsch, S. V.; Fujita, H.; Fujita, Y.; von Neumann-Cosel, P.; Neveling, R.; Papakonstantinou, P.; Pysmenetska, I.; Richter, A.; Roth, R.; Sideras-Haddad, E.; Smit, F. D.

    2016-08-01

    The isoscalar giant quadrupole resonance in 28Si and 27Al has been investigated with high-energy-resolution proton inelastic scattering at Ep=200 MeV and at scattering angles close to the maximum of Δ L =2 angular distributions with the K600 magnetic spectrometer of iThemba LABS, South Africa. Characteristic scales are extracted from the observed fine structure with a wavelet analysis and compared for 28Si with random-phase approximation and second random phase approximation calculations with an interaction derived from the Argonne V18 potential by a unitary transformation. A recent extension of the method to deformed nuclei provides the best description of the data, suggesting the significance of Landau damping.

  6. Aluminum(III) speciation with acetate and oxalate. A potentiometric and sup 27 Al NMR study

    SciTech Connect

    Thomas, F.; Rouiller, J.; Genevrier, F.; Boudot, D. ); Masion, A.; Bottero, J.Y. )

    1991-09-01

    Aluminum (III) hydrolysis and precipitation in the presence of acetic acid and oxalic acid have been studied by combining potentiometric titration and liquid-state {sup 27}Al NMR. The main aluminum species have thus been identified and quantified: unreacted hydrolyzed, complexed monomers, and the Al{sub 13} tridecamer. A solid species appeared when precipitation occurred and was quantified by difference with the other species. The quantitative evolution of these species was followed for pH values up to 5. Acetate forms weak complexes with aluminum. The precipitated phase was hypothesized to be aggregated Al{sub 13}. Oxalate forms strong multiligand complexes to form Al{sub 13} requires higher hydroxyl content. High oxalate contents (L/M > 1) inhibit tridecamer formation and precipitation occurs only at high pH values. With oxalate the precipitated phase seems to be devoid of Al{sub 13} and of a more condensed nature than it is with acetate.

  7. Natural abundance high-resolution solid state 2 H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Aliev, Abil E.; Harris, Kenneth D. M.; Apperley, David C.

    1994-08-01

    We report for the first time an approach for natural abundance solid state 2 H NMR spectroscopy involving magic angle sample spinning (MAS), high-power 1 H decoupling (HPPD) and 1 H- 2 H cross polarization (CP). Taking tetrakis(trimethylsilyl)silane (TTMSS), adamantane, 1-chloroadamantane, hexamethylbenzene (HMB), 2,2-dimethyl-1,3-propanediol (DMPD) and 2-hydroxymethyl-2-methyl-1,3-propanediol (HMPD) as examples, it has been shown that the combination of HPPD and MAS can be applied readily to study rotator phase solids, allowing isotropic peaks arising from chemically inequivalent 2 H nuclei to be resolved. For natural abundance samples of TTMSS and chloroadamantane, it has been shown that 2 H CP/HPPD/MAS NMR experiments, involving polarization transfer from 1 H to 2 H, may provide considerable sensitivity enhancement in comparison with single pulse experiments.

  8. Natural abundance high-resolution solid state 2 H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Aliev, Abil E.; Harris, Kenneth D. M.; Apperley, David C.

    1994-08-01

    We report for the first time an approach for natural abundance solid state 2H NMR spectroscopy involving magic angle sample spinning (MAS), high-power 1H decoupling (HPPD) and 1H- 2H cross polarization (CP). Taking tetrakis(trimethylsilyl)silane (TTMSS), adamantane, 1-chloroadamantane, hexamethylbenzene (HMB), 2,2-dimethyl-1,3-propanediol (DMPD) and 2-hydroxymethyl-2-methyl-1,3-propanediol (HMPD) as examples, it has been shown that the combination of HPPD and MAS can be applied readily to study rotator phase solids, allowing isotropic peaks arising from chemically inequivalent 2H nuclei to be resolved. For natural abundance samples of TTMSS and chloroadamantane, it has been shown that 2H CP/HPPD/MAS NMR experiments, involving polarization transfer from 1H to 2H, may provide considerable sensitivity enhancement in comparison with single pulse experiments.

  9. Computational prediction and analysis of the (27)Al solid-state NMR spectrum of methylaluminoxane (MAO) at variable temperatures and field strengths.

    PubMed

    Falls, Zackary; Zurek, Eva; Autschbach, Jochen

    2016-09-14

    Calculations of NMR shielding tensors and nuclear quadrupole coupling (NQC) tensors at the Kohn-Sham density functional level are used to simulate (27)Al magic-angle spinning (MAS) NMR spectra of the important olefin polymerization co-catalyst methylaluminoxane (MAO) at 77, 298, 398, and 498 K and spectrometer magnetic field inductions B ranging from 14.1 to 23.5 T. The calculations utilize the temperature (T) dependent distribution of species present in MAO determined recently by Zurek and coworkers from first-principles theory [Macromolecules, 2014, 47, 8556]. The NMR calculations suggest that variable-T and variable-B NMR measurements are able to quantify the ratio of free versus bound trimethyl-aluminum (TMA) in MAO via characteristic spectral features assigned to 3-coordinate and 4-coordinate Al sites in MAO as well as spectral features arising from free TMA or its dimer. The T-dependent distribution of species causes other characteristic features in the NMR spectra to appear/disappear that can be associated with different aluminum environments such as square vs. hexagonal faces in cage and tubular structures. The simulated spectra at 298 K and 19.6 T are in reasonably good agreement with the experimental solid-state NMR (SSNMR) spectra obtained previously for MAO gel. The promise and limitations of solid-state NMR to unravel the enigma surrounding the structure(s) of MAO are discussed. PMID:27526292

  10. Elastic Scattering and Reaction Cross Section of the 6He+27Al System Close to the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Lépine-Szily, A.; Benjamim, E. A.; Lichtenthäler, R.; Guimarães, V.; Gomes, P. R. S.; Chamon, L. C.; Hussein, M. S.; Arazi, A.; Padron, I.; Alcantara Nuñez, J.; Assunção, M.; Barioni, A.; Camargo, O.; Denke, R. Z.; de Faria, P. N.; Mendes Junior, D. R.; Pires, K. C. C.

    2006-08-01

    The RIBRAS (Radioactive Ion Beams Brazil) facility recently installed at the Pelletron Laboratory of the University of São Paulo consists of two superconducting solenoids used to produce and focalize beams of light radioactive nuclei, as 6He, 7Be,8Li etc. The low energy, light, radioactive beams available are used to study reactions close to the Coulomb barrier. The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier. Reaction cross sections were extracted from the optical model fits, using the São Paulo Potential (SPP). The reduced reaction cross sections of 6He on 27Al were compared to reduced reaction cross sections for other projectiles as 6,7Li, 9Be and 16O on 27Al and they are larger than those for stable projectiles by an amount similar to the calculated nuclear break-up cross section for this system.

  11. Investigations on the Crystal-Chemical Behavior of Transition-Metal-Bearing Aluminosilicate Garnet Solid Solutions Using 27Al and 29Si NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Palke, A. C.; Geiger, C. A.; Stebbins, J. F.

    2015-12-01

    The petrological importance of silicate garnet is derived from the presence of three distinct cation sites of varying size and coordination number. This allows for a wide range of trace, minor, and major element substitutions. However, a full and precise crystal-chemical understanding of the nature of transition metals in garnet is not at hand. Possible mechanisms of various charge-balanced substitutions (e.g. octahedral Ti4+ or tetrahedral Al3+) and the structural state of solid solutions (i.e. short- to long-range ordering) need study. We report on ongoing efforts in these directions using 27Al and 29Si Magic-Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy. Early work on synthetic and natural Fe- and Mn-bearing pyrope- and grossular-rich garnets focused on the effect these paramagnetic transition metals have in measuring and interpreting NMR spectra. These results have been expanded with NMR measurements on synthetic pyrope-rich garnets containing other paramagnetic transition metals including Cr3+, V3+, Co2+, and Ni2+ as well as diamagnetic Ti4+. NMR peaks are severely broadened in the presence of even small concentrations of Cr3+, Mn2+, and Fe3+ leading to a loss of spectral resolution. On the other hand, the spectra of garnet containing V3+, Fe2+, Co2+, and Ni2+ have better resolution and show separate paramagnetically shifted NMR peaks. In some cases, crystal-chemical information can be obtained because of the large frequency separations between the NMR peaks that can be assigned to various local atomic configurations around Al and Si. Furthermore, the 27Al NMR spectrum of a synthetic pyrope garnet with about 2% diamagnetic Ti4+ on the octahedral site showed the absence of any tetrahedral Al3+, which rules out the substitution mechanism VITi + IVAl = VIAl + IVSi in the solid solution. Our NMR investigations on garnet are now being made at the exploratory level. We think that NMR spectra of diamagnetic garnet can provide information on a

  12. Hydrolysis Studies and Quantitative Determination of Aluminum Ions Using [superscript 27]Al NMR: An Undergraduate Analytical Chemistry Experiment

    ERIC Educational Resources Information Center

    Curtin, Maria A.; Ingalls, Laura R.; Campbell, Andrew; James-Pederson, Magdalena

    2008-01-01

    This article describes a novel experiment focused on metal ion hydrolysis and the equilibria related to metal ions in aqueous systems. Using [superscript 27]Al NMR, the students become familiar with NMR spectroscopy as a quantitative analytical tool for the determination of aluminum by preparing a standard calibration curve using standard aluminum…

  13. Angular Distribution and Angular Dispersion in Collision of 19F+27Al at 114 MeV

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Dong, Yu-Chuan; Li, Song-Lin; Duan, Li-Min; Xu, Hu-Shan; Xu, Hua-Gen; Chen, Ruo-Fu; Wu, He-Yu; Han, Jian-Long; Li, Zhi-Chang; Lu, Xiu-Qin; Zhao, Kui; Liu, Jian-Cheng; Sergey, Yu-Kun

    2004-10-01

    Angular distributions of fragments B, C, N, O, F, Ne, Na, Mg and Al induced by the collision of 19F+27Al at 114 MeV have been measured. Angular dispersion parameters are extracted from the experimental data and compared with the theoretical ones. The dynamic dispersions for dissipative products depend strongly on the charge number Z of the fragments.

  14. Inferred Initial 26Al/27Al Ratios in Presolar Stardust Grains from Supernovae are Higher than Previously Estimated

    NASA Astrophysics Data System (ADS)

    Groopman, Evan; Zinner, Ernst; Amari, Sachiko; Gyngard, Frank; Hoppe, Peter; Jadhav, Manavi; Lin, Yangting; Xu, Yuchen; Marhas, Kuljeet; Nittler, Larry R.

    2015-08-01

    We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si3N4 grains found to contain large excesses of 26Mg, indicative of the initial presence of live 26Al. Ninety of the more than 450 presolar grains processed in this study contain well-correlated {δ }26{Mg}{/}24{Mg} and 27Al/24Mg ratios, derived from Nano-scale Secondary Ion Mass Spectrometer depth profiles, whose isochron-like regression lines yield inferred initial {}26{Al}{/}27{Al} ratios that, on average, are ˜1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative {δ }26{Mg}{/}24{Mg} intercepts of the isochron lines. Al contamination is potentially due to etching of the grains’ surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial {}26{Al}{/}27{Al} ratios. The presolar grains with the highest {}26{Al}{/}27{Al} ratios are from Type II supernovae whose isochron-derived initial {}26{Al}{/}27{Al} ratios greatly exceed those predicted in the He/C and He/N zones of SN models.

  15. Molecular dynamics in paramagnetic materials as studied by magic-angle spinning 2H NMR spectra.

    PubMed

    Mizuno, Motohiro; Suzuki, You; Endo, Kazunaka; Murakami, Miwa; Tansho, Masataka; Shimizu, Tadashi

    2007-12-20

    A magic-angle spinning (MAS) 2H NMR experiment was applied to study the molecular motion in paramagnetic compounds. The temperature dependences of 2H MAS NMR spectra were measured for paramagnetic [M(H2O)6][SiF6] (M=Ni2+, Mn2+, Co2+) and diamagnetic [Zn(H2O)6][SiF6]. The paramagnetic compounds exhibited an asymmetric line shape in 2H MAS NMR spectra because of the electron-nuclear dipolar coupling. The drastic changes in the shape of spinning sideband patterns and in the line width of spinning sidebands due to the 180 degrees flip of water molecules and the reorientation of [M(H2O)6]2+ about its C3 axis were observed. In the paramagnetic compounds, paramagnetic spin-spin relaxation and anisotropic g-factor result in additional linebroadening of each of the spinning sidebands. The spectral simulation of MAS 2H NMR, including the effects of paramagnetic shift and anisotropic spin-spin relaxation due to electron-nuclear dipolar coupling and anisotropic g-factor, was performed for several molecular motions. Information about molecular motions in the dynamic range of 10(2) s(-1)2H MAS NMR spectra when these paramagnetic effects are taken into account. PMID:18027914

  16. Elastic scattering and fusion cross sections for {sup 7}Be,{sup 7}Li+{sup 27}Al systems

    SciTech Connect

    Kalita, K.; Verma, S.; Singh, R.; Das, J.J.; Jhingan, A.; Madhavan, N.; Nath, S.; Varughese, T.; Sugathan, P.; Parkar, V.V.; Mahata, K.; Ramachandran, K.; Shrivastava, A.; Chatterjee, A.; Kailas, S.; Barua, S.; Basu, P.; Majumdar, H.; Sinha, M.; Bhattacharya, R.

    2006-02-15

    Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the {sup 7}Be+{sup 27}Al system at E{sub lab}=17, 19, and 21 MeV in the angular range {theta}{sub c.m.}=12 deg. An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the {sup 7}Li+{sup 27}Al system at E{sub lab}=10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the {theta}{sub lab}=12 deg. - 72 deg. range and for fusion the {alpha}-evaporation spectra from the compound nucleus were measured in the angular range {theta}{sub lab}=52 deg. - 132 deg. (142 deg. at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The {alpha}-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sections obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the {sup 7}Be+{sup 27}Al and {sup 7}Li+{sup 27}Al systems shows a similar and consistent behavior.

  17. Interplay of the elastic and inelastic channels in the 16O+27Al scattering at Elab = 280 MeV

    NASA Astrophysics Data System (ADS)

    Cappuzzello, F.; Nicolosi, D.; Linares, R.; Oliveira, J. R. B.; Lubian, J.; Agodi, C.; Carbone, D.; Cavallaro, M.; de Faria, P. N.; Foti, A.; Rodrigues, M. R. D.

    2016-06-01

    Recent data indicated a nuclear rainbow-like pattern in the elastic scattering of 16O + 27Al at E_{lab}=100 MeV that arises from couplings of the ground to the low-lying states of the 27Al nucleus. Similar effect was identified in the elastic angular distribution of 16O + 12C at E_{lab}=281 and 330 MeV. These experiments show a crucial role of microscopic details of nuclear structure in the elastic scattering of heavy ions at energies well above the Coulomb barrier. In this work we investigate the 16O + 27Al system at E_{lab}=280 MeV for which a coupled channel calculation predicts a pronounced nuclear rainbow-like structure. Obtained experimental data show evidences of an important coupling of the elastic channel to the inelastic. Coupled channel calculations reproduce the experimental angular distributions when a re-normalization factor on the real part of the optical potential is introduced. A proper theoretical approach still requires a high degree of accuracy for the nuclear structure models and new tools to deal with collective excitations.

  18. EARLY SOLAR NEBULA CONDENSATES WITH CANONICAL, NOT SUPRACANONICAL, INITIAL {sup 26}Al/{sup 27}Al RATIOS

    SciTech Connect

    MacPherson, G. J.; Bullock, E. S.; Janney, P. E.; Wadhwa, M.; Kita, N. T.; Ushikubo, T.; Davis, A. M.; Krot, A. N.

    2010-03-10

    The short-lived radionuclide {sup 26}Al existed throughout the solar nebula 4.57 Ga ago, and the initial abundance ratio ({sup 26}Al/{sup 27}Al){sub 0}, as inferred from magnesium isotopic compositions of calcium-aluminum-rich inclusions (CAIs) in chondritic meteorites, has become a benchmark for understanding early solar system chronology. Internal mineral isochrons in most CAIs measured by secondary ion mass spectrometry (SIMS) give ({sup 26}Al/{sup 27}Al){sub 0} {approx} (4-5) x 10{sup -5}, called 'canonical'. Some recent high-precision analyses of (1) bulk CAIs measured by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), (2) individual CAI minerals and their mixtures measured by laser-ablation MC-ICPMS, and (3) internal isochrons measured by multicollector (MC)-SIMS indicated a somewhat higher 'supracanonical' ({sup 26}Al/{sup 27}Al){sub 0} ranging from (5.85 {+-} 0.05) x 10{sup -5} to >7 x 10{sup -5}. These measurements were done on coarse-grained Type B and Type A CAIs that probably formed by recrystallization and/or melting of fine-grained condensate precursors. Thus the supracanonical ratios might record an earlier event, the actual nebular condensation of the CAI precursors. We tested this idea by performing in situ high-precision magnesium isotope measurements of individual minerals in a fine-grained CAI whose structures and volatility-fractionated trace element abundances mark it as a primary solar nebula condensate. Such CAIs are ideal candidates for the fine-grained precursors to the coarse-grained CAIs, and thus should best preserve a supracanonical ratio. Yet, our measured internal isochron yields ({sup 26}Al/{sup 27}Al){sub 0} = (5.27 {+-} 0.17) x 10{sup -5}. Thus our data do not support the existence of supracanonical ({sup 26}Al/{sup 27}Al){sub 0} = (5.85-7) x 10{sup -5}. There may not have been a significant time interval between condensation of the CAI precursors and their subsequent melting into coarse-grained CAIs.

  19. Dynamic effects in MAS and MQMAS NMR spectra of half-integer quadrupolar nuclei: calculations and an application to the double perovskite cryolite.

    PubMed

    Kotecha, Mrignayani; Chaudhuri, Santanu; Grey, Clare P; Frydman, Lucio

    2005-11-30

    Dynamic processes such as chemical exchange or rotations between inequivalent orientations can affect the magic-angle spinning (MAS) and the multiple-quantum (MQ) MAS NMR spectra of half-integer quadrupolar nuclei. The present paper discusses such dynamic multisite MAS and MQMAS effects and applies them to study the dynamic processes that occur in the double perovskite cryolite, Na3AlF6. Dynamic line shape simulations invoking a second-order broadening of the central transition and relying on the semiclassical Bloch-McConnell formalism for chemical exchange were performed for a variety of exchange models possessing different symmetries. Fitting experimental variable-temperature cryolite 23Na NMR data with this formalism revealed that the two inequivalent sodium sites in this mineral undergo an exchange characterized by a broad distribution of rates. To further assess this dynamic process a variety of 27Al and 19F MAS NMR studies were also undertaken; quantitative 27Al-19F dipolar coupling measurements then revealed a dynamic motion of the AlF6 octahedra that were qualitatively consistent with predictions stemming from molecular dynamic simulations on this double perovskite. PMID:16305261

  20. Phase evolution of Na2O-Al2O3-SiO2-H2O gels in synthetic aluminosilicate binders.

    PubMed

    Walkley, Brant; San Nicolas, Rackel; Sani, Marc-Antoine; Gehman, John D; van Deventer, Jannie S J; Provis, John L

    2016-04-01

    This study demonstrates the production of stoichiometrically controlled alkali-aluminosilicate gels ('geopolymers') via alkali-activation of high-purity synthetic amorphous aluminosilicate powders. This method provides for the first time a process by which the chemistry of aluminosilicate-based cementitious materials may be accurately simulated by pure synthetic systems, allowing elucidation of physicochemical phenomena controlling alkali-aluminosilicate gel formation which has until now been impeded by the inability to isolate and control key variables. Phase evolution and nanostructural development of these materials are examined using advanced characterisation techniques, including solid state MAS NMR spectroscopy probing (29)Si, (27)Al and (23)Na nuclei. Gel stoichiometry and the reaction kinetics which control phase evolution are shown to be strongly dependent on the chemical composition of the reaction mix, while the main reaction product is a Na2O-Al2O3-SiO2-H2O type gel comprised of aluminium and silicon tetrahedra linked via oxygen bridges, with sodium taking on a charge balancing function. The alkali-aluminosilicate gels produced in this study constitute a chemically simplified model system which provides a novel research tool for the study of phase evolution and microstructural development in these systems. Novel insight of physicochemical phenomena governing geopolymer gel formation suggests that intricate control over time-dependent geopolymer physical properties can be attained through a careful precursor mix design. Chemical composition of the main N-A-S-H type gel reaction product as well as the reaction kinetics governing its formation are closely related to the Si/Al ratio of the precursor, with increased Al content leading to an increased rate of reaction and a decreased Si/Al ratio in the N-A-S-H type gel. This has significant implications for geopolymer mix design for industrial applications. PMID:26911317

  1. Cross sections and differential spectra for reactions of 2-20 MeV neutrons of /sup 27/Al

    SciTech Connect

    Blann, M.; Komoto, T.T.

    1988-01-01

    This report summarizes product yields, secondary n,p and ..cap alpha.. spectra, and ..gamma..-ray spectra calculated for incident neutrons of 2-20 MeV on /sup 27/Al targets. Results are all from the code ALICE, using the version ALISO which does weighting of results for targets which are a mix of isotopes. Where natural isotopic targets are involved, yields and n,p,..cap alpha.. spectra will be reported weighted over isotopic yields. Gamma-ray spectra, however, will be reported for the most abundant isotope.

  2. Photon-photon correlation in the {sup 36}Ar+{sup 27}Al reaction at 95 MeV/nucleon

    SciTech Connect

    Badala, A.; Palmeri, A.; Pappalardo, G.S.; Russo, A.C.; Barbera, R.; Riggi, F.; Russo, G.; Russo, G.

    1995-06-12

    The technique of intensity interferometry has been applied to the pairs of high-energy photons coming from the {sup 36}Ar+{sup 27}Al reaction at 95 MeV/nucleon. For the first time, the experimental correlation distributions {ital C}({ital q}{sub rel}) and {ital C}({ital q}{sub 0}), as functions of the relative momentum and energy of the two detected photons, have been analyzed in order to extract both the spatial size and lifetime of the emitting source. The found values are in agreement with dynamical approaches based on the {ital bremsstrahlung} radiation picture from first-chance proton-neutron collisions.

  3. Neutral pion production in the [sup 16]O+[sup 27]Al reaction at 94 MeV/nucleon

    SciTech Connect

    Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S.; Riggi, F.; Russo, A.C.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Maiolino, C.; Migneco, E.; Piattelli, P.; Russo, G.; Sapienza, P.; Peghaire, A. Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I95129 Catania Istituto Nazionale di Fisica Nucleare, Laboratorio Nazionale del Sud, Catania Grand Accelerateur National d'Ions Lourds, Caen )

    1993-01-01

    The production of neutral pions in the reaction [sup 16]O+[sup 27]Al at 94 MeV/nucleon was studied with a multidetector, which includes 180 BaF[sub 2] modules. Kinetic energy spectra for several laboratory angles were measured. The total cross section for neutral pion production was deduced. Results were compared with previous findings on charged pions from the same reaction at the same energy and with the prediction of a dynamical model based on the numerical solution of the Boltzmann-Nordheim-Vlasov equation.

  4. High-resolution /sup 27/Al NMR study of the states of aluminum atoms in modified natural mordenite

    SciTech Connect

    Il'in, V.G.; Turutina, N.V.; Brei, V.V.; Voloshinets, V.G.; Onishchenko, A.D.

    1987-09-01

    High-resolution /sup 27/Al NMR has been applied to the states of aluminum in modified natural mordenite. Acid treatment of the natural mordenite and heat treatment of the ammonium form alter the coordination state of 6-8% of the aluminum atoms from tetrahedral (in the framework) to octahedral (at the inner surfaces of the zeolite cavities). In that state, the aluminum can exchange with Na/sup +/, NH/sub 4//sup +/, and other cations. This change in coordination state should have a considerable effect on the catalytic parameters of zeolites.

  5. [sup 31]P and [sup 27]Al NMR investigations of highly acidic, aqueous solutions containing aluminum and phosphorus

    SciTech Connect

    Mortlock, R.F.; Bell, A.T.; Radke, C.J. Univ. of California, Berkeley )

    1993-01-21

    [sup 31]P and [sup 27]Al NMR spectroscopies have been used to characterize acidic, aqueous solutions of orthophosphoric acid, aluminum chloride, and tetramethylammonium (TMA) hydroxide. The final compositions of the solutions range from 0.1 to 1 mol % P, 0.0 to 20 mol % HCl, P/Al = 0.1 to 20, and P/(TMA)[sub 2]O = 2 to 20. Soluble aluminophosphate cations form reactions of hexaaqua Al monomeric cations, [Al(H[sub 2]O)[sub 6

  6. Nuclear rainbow in the 16O + 27AL system: The role of couplings at energies far above the barrier

    NASA Astrophysics Data System (ADS)

    Pereira, D.; Linares, R.; Oliveira, J. R. B.; Lubian, J.; Chamon, L. C.; Gomes, P. R. S.; Cunsolo, A.; Cappuzzello, F.; Cavallaro, M.; Carbone, D.; Foti, A.

    2012-04-01

    High precision elastic and inelastic angular distributions have been measured for the 16O + 27Al system at a beam energy of 100 MeV. The data analysis confirms a rainbow formation as already predicted by parameter-free Coupled Channel calculations. It also helps to reveal the crucial role of inelastic couplings in the rainbow formation for heavier systems even at energies far above the Coulomb barrier. This feature, well known in atomic/molecular scattering, is experimentally studied for the first time in Nuclear Physics.

  7. Investigation of locally favored structures in Al-La-Ni metallic glasses using ^27Al NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sandor, Magdalena; Xi, Xuekui; Wu, Yue

    2008-10-01

    Al-TM-RE (TM= transition metal, RE = rare earth) bulk metallic glasses (BMGs) with high Al content have gained much research interest due to their high potential as structural and functional materials. The first recent fabrication of La85-xAlxNi15 (15 <= x <= 70) BMGs have inspired an NMR systematic study of their locally favored structures (LFSs). These BMGs are reported to show characteristics of high thermal stability, fragility, and considerable mechanical strength. ^27Al NMR spectroscopy and nutation experiments are performed to unveil the sensitive structural dependence on line width and quadrupolar frequency with Al composition. It is observed that maximum glass forming ability (GFA) for this system prefers a decrease of symmetry at Al sites. Minimal GFA corresponding to instances of high symmetry occur in Al-rich and Al-poor regimes. These results, in addition to previous work, suggest that Ni and La atoms have unique local chemical and topological environments at different Al compositions. The monotonic decrease of relatively small ^27Al Knight shifts with increasing Al concentration demonstrates the evolution of local electronic structure at Al sites. This study is valuable in correlating the unique role that TM and RE elements play in local compositional and geometrical order of high glass-forming Al-based BMGs.

  8. 27Al fourier-transform electron-spin-echo modulation of Cu 2+-doped zeolites A and X

    NASA Astrophysics Data System (ADS)

    Goldfarb, Daniella; Kevan, Larry

    Cu 2+-doped NaA, CaA, and NaX zeolites were studied using the electron-spin-echo modulation (ESEM) method. In both hydrated and dehydrated samples 27Al modulation has been observed. The time-domain ESEM traces were Fourier transformed and analyzed in the frequency domain. All FT-ESEM spectra of the hydrated samples showed a single peak at the Larmor frequency of 27Ai, indicating that the zeeman interaction is dominant and that the 27Al quadrupole and hyperfine interactions are relatively small. Considerable changes in the spectrum appear upon dehydration. Several frequencies significantly different from the Larmor frequency appear and the spectrum depends on the major cocation present. The major features of the spectra of the dehydrated zeolites could be theoretically reproduced, using exact diagonalization of the nuclear Hamiltonian, with relatively large isotropic hyperfine and quadrupole coupling constants. For example, in CuCaA and CuNaA zeolites the isotropic hyperfine constant is in the range of 0.2-0.5 and 0.8-1.0 MHz, respectively, with the quadrupole coupling constant in the range of 6-10 MHz for both.

  9. Fluid flow dynamics in MAS systems

    NASA Astrophysics Data System (ADS)

    Wilhelm, Dirk; Purea, Armin; Engelke, Frank

    2015-08-01

    The turbine system and the radial bearing of a high performance magic angle spinning (MAS) probe with 1.3 mm-rotor diameter has been analyzed for spinning rates up to 67 kHz. We focused mainly on the fluid flow properties of the MAS system. Therefore, computational fluid dynamics (CFD) simulations and fluid measurements of the turbine and the radial bearings have been performed. CFD simulation and measurement results of the 1.3 mm-MAS rotor system show relatively low efficiency (about 25%) compared to standard turbo machines outside the realm of MAS. However, in particular, MAS turbines are mainly optimized for speed and stability instead of efficiency. We have compared MAS systems for rotor diameter of 1.3-7 mm converted to dimensionless values with classical turbomachinery systems showing that the operation parameters (rotor diameter, inlet mass flow, spinning rate) are in the favorable range. This dimensionless analysis also supports radial turbines for low speed MAS probes and diagonal turbines for high speed MAS probes. Consequently, a change from Pelton type MAS turbines to diagonal turbines might be worth considering for high speed applications. CFD simulations of the radial bearings have been compared with basic theoretical values proposing considerably smaller frictional loss values. The discrepancies might be due to the simple linear flow profile employed for the theoretical model. Frictional losses generated inside the radial bearings result in undesired heat-up of the rotor. The rotor surface temperature distribution computed by CFD simulations show a large temperature gradient over the rotor.

  10. Fluid flow dynamics in MAS systems.

    PubMed

    Wilhelm, Dirk; Purea, Armin; Engelke, Frank

    2015-08-01

    The turbine system and the radial bearing of a high performance magic angle spinning (MAS) probe with 1.3mm-rotor diameter has been analyzed for spinning rates up to 67kHz. We focused mainly on the fluid flow properties of the MAS system. Therefore, computational fluid dynamics (CFD) simulations and fluid measurements of the turbine and the radial bearings have been performed. CFD simulation and measurement results of the 1.3mm-MAS rotor system show relatively low efficiency (about 25%) compared to standard turbo machines outside the realm of MAS. However, in particular, MAS turbines are mainly optimized for speed and stability instead of efficiency. We have compared MAS systems for rotor diameter of 1.3-7mm converted to dimensionless values with classical turbomachinery systems showing that the operation parameters (rotor diameter, inlet mass flow, spinning rate) are in the favorable range. This dimensionless analysis also supports radial turbines for low speed MAS probes and diagonal turbines for high speed MAS probes. Consequently, a change from Pelton type MAS turbines to diagonal turbines might be worth considering for high speed applications. CFD simulations of the radial bearings have been compared with basic theoretical values proposing considerably smaller frictional loss values. The discrepancies might be due to the simple linear flow profile employed for the theoretical model. Frictional losses generated inside the radial bearings result in undesired heat-up of the rotor. The rotor surface temperature distribution computed by CFD simulations show a large temperature gradient over the rotor. PMID:26073599

  11. MAS NMR of HIV-1 protein assemblies

    NASA Astrophysics Data System (ADS)

    Suiter, Christopher L.; Quinn, Caitlin M.; Lu, Manman; Hou, Guangjin; Zhang, Huilan; Polenova, Tatyana

    2015-04-01

    The negative global impact of the AIDS pandemic is well known. In this perspective article, the utility of magic angle spinning (MAS) NMR spectroscopy to answer pressing questions related to the structure and dynamics of HIV-1 protein assemblies is examined. In recent years, MAS NMR has undergone major technological developments enabling studies of large viral assemblies. We discuss some of these evolving methods and technologies and provide a perspective on the current state of MAS NMR as applied to the investigations into structure and dynamics of HIV-1 assemblies of CA capsid protein and of Gag maturation intermediates.

  12. MAS NMR of HIV-1 protein assemblies.

    PubMed

    Suiter, Christopher L; Quinn, Caitlin M; Lu, Manman; Hou, Guangjin; Zhang, Huilan; Polenova, Tatyana

    2015-04-01

    The negative global impact of the AIDS pandemic is well known. In this perspective article, the utility of magic angle spinning (MAS) NMR spectroscopy to answer pressing questions related to the structure and dynamics of HIV-1 protein assemblies is examined. In recent years, MAS NMR has undergone major technological developments enabling studies of large viral assemblies. We discuss some of these evolving methods and technologies and provide a perspective on the current state of MAS NMR as applied to the investigations into structure and dynamics of HIV-1 assemblies of CA capsid protein and of Gag maturation intermediates. PMID:25797001

  13. Tunable millisecond narrow-band Nd:GSGG laser around 1336.6 nm for 27Al+ optical clock

    NASA Astrophysics Data System (ADS)

    Wang, M.-Q.; Zhang, F.-F.; Li, J.-J.; Wang, Z.-M.; Zong, N.; Zhang, S.-J.; Yang, F.; Yuan, L.; Bo, Y.; Cui, D.-F.; Peng, Q.-J.; Xu, Z.-Y.

    2016-05-01

    We developed a narrow-band, Nd:GSGG ring laser tunable around 1336.6 nm with a tuning range more than 24 pm. The maximum output energy is 0.26 J per pulse with a pulse width of 900 μs and a pulse repetition rate of 10 Hz. The root-mean-square of wavelength stability in 1 h is 0.27 pm, and M2 factor is 1.06 at the output energy of 0.16 J per pulse. It can be a good candidate of the fundamental laser, of which the eighth-harmonic generation at 167.0787 nm can be used to induce the 27Al+ ion by the 1S0↔1P1 transition for laser cooling when it is used as the medium for optical clock.

  14. Spin dependence of the coherent scattering lengths of /sup 27/Al and admixture of s- and d-partial waves

    SciTech Connect

    Mughab, S.F.

    1985-01-01

    A long standing discrepancy between measurements and calculations of the sign of the incoherent scattering length is attributed to two sources: (1) spin dependence of the potential scattering radius and (2) identification of additional s-wave resonances at higher neutron energies. Detailed examination of the reaction /sup 27/Al (n vector,..gamma..) /sup 28/Al induced by thermal neutrons revealed that R/sub +/ - R/sub -/ = 0.32 +- 0.10 fm. Also shape fit analysis of the total cross section showed the presence of s-wave resonances at neutron energies 280, 386, 422, 491, 523, and 615 keV. One interesting outcome is the demonstration of the admixture of s- and d-wave partial waves in these resonances and the presence of a large d-wave neutron strength in the above energy region.

  15. Incommensurate to commensurate antiferromagnetism in CeRhAl4Si2 : An 27Al NMR study

    NASA Astrophysics Data System (ADS)

    Sakai, H.; Hattori, T.; Tokunaga, Y.; Kambe, S.; Ghimire, N. J.; Ronning, F.; Bauer, E. D.; Thompson, J. D.

    2016-01-01

    27Al nuclear magnetic resonance (NMR) experiments have been performed on a single crystal of CeRhAl4Si2 , which is an antiferromagnetic Kondo-lattice compound with successive antiferromagnetic transitions of TN 1=14 K and TN 2=9 K at zero external field. In the paramagnetic state, the Knight shifts, quadrupolar frequency, and asymmetric parameter of electrical field gradient on the Al sites have been determined, which have local orthorhombic symmetry. The transferred hyperfine coupling constants are also determined. Analysis of the NMR spectra indicates that a commensurate antiferromagnetic structure exists below TN 2, but an incommensurate modulation of antiferromagnetic moments is present in the antiferromagnetic state between TN 1 and TN 2. The spin-lattice relaxation rate suggests that the 4 f electrons behave as local moments at temperatures above TN 1.

  16. Spin-Triplet Superconductivity in UNi2Al3 Revealed by the 27Al Knight Shift Measurement

    NASA Astrophysics Data System (ADS)

    Ishida, K.; Ozaki, D.; Kamatsuka, T.; Tou, H.; Kyogaku, M.; Kitaoka, Y.; Tateiwa, N.; Sato, N. K.; Aso, N.; Geibel, C.; Steglich, F.

    2002-06-01

    We report 27Al Knight shift ( 27K) measurement on a single-crystal UNi2Al3 that reveals a coexistence of superconductivity and a spin-density-wave (SDW) type of magnetic ordering ( TSDW = 4.5 K). The spin part of 27K, 27Ks, does not change down to 50 mK across the superconducting (SC) transition temperature Tc~0.9 K. In contrast with the isostructural compound UPd2Al3 ( Tc~2 K), which was identified to be a spin-singlet d-wave superconductor, the behavior of 27K strongly supports that UNi2Al3, like UPt3 and Sr2RuO4, belongs to a class of spin-triplet SC pairing state superconductors.

  17. Formation of Po isotopes in the reactions {sup 27}Al + {sup 175}Lu and {sup 31}P + {sup 169}Tm

    SciTech Connect

    Andreev, A.N.; Bogdanov, D.D.; Eremin, A.V.

    1995-05-01

    The excitation functions and the cross sections for the formation of {sup 192-198}Po isotopes in the reactions {sup 27}Al + {sup 175}Lu and {sup 31}P + {sup 169}Tm are measured. A comparison of the results obtained for these reactions with the data on the cross sections for the formation of Po isotopes in the reaction {sup 100}Mo + {sup 92-100}Mo leads to the conclusion that the characteristics of the evaporation channel do not depend on the mass of the bombarding ion up to the complete symmetry in the input channel. It is shown that the experimental data can be adequately described using the statistical approach to the deexcitation of a compound nucleus only under the assumption that the liquid-drop fission barrier is reduced significantly for neutron-deficient Po isotopes. 21 refs., 5 figs., 2 tabs.

  18. Fusion hindrance for {sup 27}Al + {sup 45}Sc and other systems with positive Q-values.

    SciTech Connect

    Jiang, C. L.; Rehm, K. E.; Esbensen, H.; Back, B. B.; Janssens, R. V. F.; Collon, P.; Deibel, C. M.; DiGiovine, B.; Figueira, J. M.; Greene, J. P.; Henderson, D. J.; Lee, H. Y.; Notani, M.; Marley, S. T.; Pardo, R. C.; Patel, N.; Seweryniak, D.; Tang, X. D.; Ugalde, C.; Zhu, S.; Physics; Univ. of Notre Dame; Michigan State Univ.; TANDAR; Western Michigan Univ.; Colorado School of Mines

    2010-01-01

    Fusion evaporation cross sections for the {sup 27}Al+{sup 45}Sc (Q=9.63 MeV) system are measured down to about 300 nb. Deviations from standard coupled-channels calculations were observed in this system at the lowest energies. The steep fall-off of the fusion cross sections can be reproduced by calculations using a shallow potential model, which was originally developed to explain the hindrance behavior of heavy-ion fusion in medium-mass systems with negative Q values. Comparisons of the hindrance behavior between the present experiment and other systems, for example, {sup 28}Si+{sup 30}Si (Q = 14.3 MeV) and {sup 36}S+{sup 48}Ca (Q = 7.55 MeV) are presented.

  19. Elastic Scattering of 7Li+27Al at Backward Angles in the 7-11 MeV Energy Range for Application in RBS

    NASA Astrophysics Data System (ADS)

    Carnelli, P. F. F.; Abriola, D.; Arazi, A.; Capurro, O. A.; Cardona, M. A.; Fernández Niello, J. O.; Figueira, J. M.; Fimiani, L.; Grinberg, P.; Hojman, D.; Martí, G. V.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.

    2010-08-01

    We have measured elastic excitation functions for the 7Li+27Al system, in an energy range close to its Coulomb barrier (Elab = 8.4 MeV) in steps of 0.25 MeV. For this purpose, an array of eight surface-barrier detectors was used. To get an insight on the background composition (mainly α particles), a telescope-detector was used for atomic-number identification. Identical measurements for the 6Li+27Al system are planned for the near future.

  20. Elastic Scattering of {sup 7}Li+{sup 27}Al at Backward Angles in the 7-11 MeV Energy Range for Application in RBS

    SciTech Connect

    Carnelli, P. F. F.; Arazi, A.; Cardona, M. A.; Figueira, J. M.; Hojman, D.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.; Abriola, D.; Capurro, O. A.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Fernandez Niello, J. O.

    2010-08-04

    We have measured elastic excitation functions for the {sup 7}Li+{sup 27}Al system, in an energy range close to its Coulomb barrier (E{sub lab} = 8.4 MeV) in steps of 0.25 MeV. For this purpose, an array of eight surface-barrier detectors was used. To get an insight on the background composition (mainly {alpha} particles), a telescope-detector was used for atomic-number identification. Identical measurements for the {sup 6}Li+{sup 27}Al system are planned for the near future.

  1. Analysis of reaction modes of low energy reactions of deuterons with (56)Fe and (27)Al nuclei

    NASA Astrophysics Data System (ADS)

    Al-Quraishi, Saleh Ibrahim

    1997-11-01

    Measurements of deuteron-induced cross sections have been made for targets of 27Al and 56Fe. Reactions studied included elastic scattering, inelastic scattering, (d,p), (d,n) and (d,/alpha). No evidence was found for either (d,3H) or (d,3He) at the two bombarding energies (5 and 7 MeV) for either target. An optical model analysis was completed for the elastic scattering at both energies for each target. A particular effort was made to cover a large angular range (10o to 140o) with small errors. From the optical model analysis, reaction cross section values are derived. Spectra for (d,p), (d,n) and (d,/alpha) are compared with Hauser-Feshbach calculations. The (d,p) and (d,n) spectra show evidence for both stripping reactions and break-up reactions. Values for the fraction of the reaction cross section, which is due to compound nuclear reactions, are derived. Comparison with values of this parameter at higher energies derived using a different technique is presented. Some systematics of the break-up cross section are discussed.

  2. Energy loss measurements of 63Cu, 28Si and 27Al heavy ions crossing thin Polyvinylchloride (PVC) foil

    NASA Astrophysics Data System (ADS)

    Dib, A.; Ammi, H.; Guesmia, A.; Msimanga, M.; Mammeri, S.; Hedibel, M.; Guedioura, B.; Pineda-Vargas, C. A.

    2015-11-01

    Experimental stopping data of, 63Cu, 28Si and 27Al heavy ions in thin Polyvinylchloride (H3C2Cl1) foil have been obtained over the 0.045-0.50 MeV/nucleon energy range. The measured energy losses were carried out by Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer. A continuous stopping power data obtained in this work are well fitted by our proposed semi-empirical formula and the results are compared to those calculated by LSS formula or generated by SRIM-2013 and MSTAR predictions. Calculations using our formula agree well with the obtained experimental stopping powers, while the LSS formula underestimates the experimental data in the whole investigated energy range. In this work a simple expression for electronic stopping power of heavy ions at low energy in solid targets is introduced. This formula is based on the Firsov and Lindhard-Sharff stopping power models with a small modification made to the original expression, by incorporating the effective charge of moving ions concept and with exponential fit function.

  3. Mas' Making and Pedagogy: Imagined Possibilities

    ERIC Educational Resources Information Center

    Fournillier, Janice B.

    2009-01-01

    In this article I draw on an ethnographic case study that examined mas' makers' perceptions of the learning/teaching practices at work in the production of costumes for Trinidad and Tobago's annual Carnival celebrations. During the 2005 Carnival season I spent four months in the field, my country of birth, and collected data through participant…

  4. Critical fluctuations in DOPC/DPPC-d62/cholesterol mixtures: 2H magnetic resonance and relaxation.

    PubMed

    Davis, James H; Ziani, Latifa; Schmidt, Miranda L

    2013-07-28

    Static and magic angle spinning (MAS) (2)H nuclear magnetic resonance experiments have been performed on a series of multilamellar dispersions of di-oleoyl-sn-glycero-3-phosphocholine/di-palmitoyl-sn-glycero-3-phosphocholine-d62/cholesterol in water to investigate the compositional fluctuations which occur in the region of the line of critical points for this ternary system. The strong dependence of the MAS line widths on temperature, sample composition, and spinning rate provides a direct measure of the magnitude of the fluctuations in the (2)H quadrupolar Hamiltonian. These data are analyzed in terms of models for critical fluctuations in composition leading to a value for the critical index for the correlation length, ν(c) = 0.628, consistent with a three dimensional Ising model. PMID:23902029

  5. Determination of nuclear distances and chemical-shift anisotropy from 1H MAS NMR sideband patterns of surface OH groups

    NASA Astrophysics Data System (ADS)

    Fenzke, Dieter; Hunger, Michael; Pfeifer, Harry

    A procedure is described which allows a separate determination of the proton-aluminum distance and of the chemical-shift anisotropy for the bridging OH groups of crystalline molecular sieves from their 'H MAS NMR sideband patterns. For the bridging OH groups which point into the 6-rings of the framework (line "c"), the 1H- 27Al distance could be determined to be 0.237 ± 0.004 and 0.234 ± 0.004 nm for molecular sieves of type H-Y and SAPO-5, respectively. In contrast, for the bridging OH groups of the 12-rings (line "b"), the corresponding distances are equal and distinctly larger, 0.248 ± 0.004 nm. Within the limits of error, the values of the chemical-shift anisotropy are equal (about 19 ± 2 ppm) except for line b of SAPO-5, which exhibits a much smaller value of 14.5 ± 2 ppm.

  6. Rapid solid-state NMR of deuterated proteins by interleaved cross-polarization from 1H and 2H nuclei

    NASA Astrophysics Data System (ADS)

    Bjerring, Morten; Paaske, Berit; Oschkinat, Hartmut; Akbey, Ümit; Nielsen, Niels Chr.

    2012-01-01

    We present a novel sampling strategy, interleaving acquisition of multiple NMR spectra by exploiting initial polarization subsequently from 1H and 2H spins, taking advantage of their different T1 relaxation times. Different 1H- and 2H-polarization based spectra are in this way simultaneously recorded improving either information content or sensitivity by adding spectra. The so-called Relaxation-optimized Acquisition of Proton Interleaved with Deuterium (RAPID) 1H → 13C/ 2H → 13C CP/MAS multiple-acquisition method is demonstrated by 1D and 2D experiments using a uniformly 2H, 15N, 13C-labeled α-spectrin SH3 domain sample with all or 30% back-exchanged labile 2H to 1H. It is demonstrated how 1D 13C CP/MAS or 2D 13C- 13C correlation spectra initialized with polarization from either 1H or 2H may be recorded simultaneously with flexibility to be added or used individually for spectral editing. It is also shown how 2D 13C- 13C correlation spectra may be recorded interleaved with 2H- 13C correlation spectra to obtain 13C- 13C correlations along with information about dynamics from 2H sideband patterns.

  7. Ultra-low temperature MAS-DNP.

    PubMed

    Lee, Daniel; Bouleau, Eric; Saint-Bonnet, Pierre; Hediger, Sabine; De Paëpe, Gaël

    2016-03-01

    Since the infancy of NMR spectroscopy, sensitivity and resolution have been the limiting factors of the technique. Regular essential developments on this front have led to the widely applicable, versatile, and powerful spectroscopy that we know today. However, the Holy Grail of ultimate sensitivity and resolution is not yet reached, and technical improvements are still ongoing. Hence, high-field dynamic nuclear polarization (DNP) making use of high-frequency, high-power microwave irradiation of electron spins has become very promising in combination with magic angle sample spinning (MAS) solid-state NMR experiments. This is because it leads to a transfer of the much larger polarization of these electron spins under suitable irradiation to surrounding nuclei, greatly increasing NMR sensitivity. Currently, this boom in MAS-DNP is mainly performed at minimum sample temperatures of about 100K, using cold nitrogen gas to pneumatically spin and cool the sample. This Perspective deals with the desire to improve further the sensitivity and resolution by providing "ultra"-low temperatures for MAS-DNP, using cryogenic helium gas. Different designs on how this technological challenge has been overcome are described. It is shown that stable and fast spinning can be attained for sample temperatures down to 30K using a large cryostat developed in our laboratory. Using this cryostat to cool a closed-loop of helium gas brings the additional advantage of sample spinning frequencies that can greatly surpass those achievable with nitrogen gas, due to the differing fluidic properties of these two gases. It is shown that using ultra-low temperatures for MAS-DNP results in substantial experimental sensitivity enhancements and according time-savings. Access to this temperature range is demonstrated to be both viable and highly pertinent. PMID:26920837

  8. Ultra-low temperature MAS-DNP

    NASA Astrophysics Data System (ADS)

    Lee, Daniel; Bouleau, Eric; Saint-Bonnet, Pierre; Hediger, Sabine; De Paëpe, Gaël

    2016-03-01

    Since the infancy of NMR spectroscopy, sensitivity and resolution have been the limiting factors of the technique. Regular essential developments on this front have led to the widely applicable, versatile, and powerful spectroscopy that we know today. However, the Holy Grail of ultimate sensitivity and resolution is not yet reached, and technical improvements are still ongoing. Hence, high-field dynamic nuclear polarization (DNP) making use of high-frequency, high-power microwave irradiation of electron spins has become very promising in combination with magic angle sample spinning (MAS) solid-state NMR experiments. This is because it leads to a transfer of the much larger polarization of these electron spins under suitable irradiation to surrounding nuclei, greatly increasing NMR sensitivity. Currently, this boom in MAS-DNP is mainly performed at minimum sample temperatures of about 100 K, using cold nitrogen gas to pneumatically spin and cool the sample. This Perspective deals with the desire to improve further the sensitivity and resolution by providing "ultra"-low temperatures for MAS-DNP, using cryogenic helium gas. Different designs on how this technological challenge has been overcome are described. It is shown that stable and fast spinning can be attained for sample temperatures down to 30 K using a large cryostat developed in our laboratory. Using this cryostat to cool a closed-loop of helium gas brings the additional advantage of sample spinning frequencies that can greatly surpass those achievable with nitrogen gas, due to the differing fluidic properties of these two gases. It is shown that using ultra-low temperatures for MAS-DNP results in substantial experimental sensitivity enhancements and according time-savings. Access to this temperature range is demonstrated to be both viable and highly pertinent.

  9. Residue specific hydration of primary cell wall potato pectin identified by solid-state 13C single-pulse MAS and CP/MAS NMR spectroscopy.

    PubMed

    Larsen, Flemming H; Byg, Inge; Damager, Iben; Diaz, Jerome; Engelsen, Søren B; Ulvskov, Peter

    2011-05-01

    Hydration of rhamnogalacturonan-I (RG-I) derived from potato cell wall was analyzed by (13)C single-pulse (SP) magic-angle-spinning (MAS) and (13)C cross-polarization (CP) MAS nuclear magnetic resonance (NMR) and supported by (2)H SP/MAS NMR experiments. The study shows that the arabinan side chains hydrate more readily than the galactan side chains and suggests that the overall hydration properties can be controlled by modifying the ratio of these side chains. Enzymatic modification of native (NA) RG-I provided samples with reduced content of arabinan (sample DA), galactan (sample DG), or both side chains (sample DB). Results of these samples suggested that hydration properties were determined by the length and character of the side chains. NA and DA exhibited similar hydration characteristics, whereas DG and DB were difficult to hydrate because of the less hydrophilic properties of the rhamnose-galacturonic acid (Rha-GalA) backbone in RG-I. Potential food ingredient uses of RG-I by tailoring of its structure are discussed. PMID:21462966

  10. Optical and scintillation properties of ce-doped (Gd2Y1)Ga2.7Al2.3O12 single crystal grown by Czochralski method

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Wu, Yuntao; Ding, Dongzhou; Li, Huanying; Chen, Xiaofeng; Shi, Jian; Ren, Guohao

    2016-06-01

    Multicomponent garnets, due to their excellent light yield and energy resolution, become one of the most promising scintillators used for homeland security and nuclear non-proliferation applications. This work focuses on the optimization of Ce-doped (Gd,Y)3(Ga,Al)5O12 scintillators using a combination strategy of pre-screening and scale-up. Ce-doped GdxY1-xGayAl5-yO12 (x=1, 2 and y=2, 2.2, 2.5, 2.7, 3) polycrystalline powders were prepared by high-temperature solid state reaction method. The desired garnet phase in all the samples was confirmed using X-ray diffraction measurement. By comparing the radioluminescence intensity, the highest scintillation efficiency was achieved at a component of Gd2Y1Ga2.7Al2.3O12:Ce powders. A (Gd2Y1)Ga2.7Al2.3O12 doped with 1% Ce single crystal with dimensions of Ø35×40 mm was grown by Czochralski method using a <111> oriented seed. Luminescence and scintillation properties were measured. An optical transmittance of 84% was achieved in the concerned wavelength from 500 to 800 nm. Its 5d-4f emission of Ce3+ is at 530 nm. The light yield of a Ce1%: Gd2Y1Ga2.7Al2.3O12 single crystal slab at a size of 5×5×1 mm3 can reach about 65,000±3000 Ph/MeV along with two decay components of 94 and 615 ns under 137Cs source irradiation.

  11. Impact-parameter dependence of neutral pion production in the [sup 36]Ar on [sup 27]Al collision at 95 MeV/nucleon

    SciTech Connect

    Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S.; Riggi, F.; Russo, A.C.; Russo, G.; Turrisi, R.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Maiolino, C.; Migneco, E.; Piattelli, P.; Sapienza, P.; Peghaire, A. Dipartimento di Fisica, Universita di Catania, Corso Italia, 57-95129 Catania Istituto Nazionale di Fisica Nucleare, Laboratorio Nazionale del Sud, Rome Grand Accelerateur National d'Ions Lourds, Caen )

    1993-11-01

    Neutral pion production has been studied in the [sup 36]Ar+[sup 27]Al reaction at 95 MeV/nucleon with the aim to get a quantitative estimate of its impact-parameter dependence. A near 4[pi] multidetector has been used to detect both the gamma rays originating from the [pi][sup 0] decay and the associated charged particles. The charged particle multiplicity has been used in the present analysis as a global variable to extract the impact parameter scale. A comparison with a Boltzmann-Nordheim-Vlasov calculation, whcih takes into account the effect of pion reabsorption in the nuclear medium, has been performed.

  12. Three-body final state breakup in the27Al(14N, X) reaction at 116 MeV bombarding energy

    NASA Astrophysics Data System (ADS)

    Petrascu, M.; Isbasescu, A.; Lazar, I.; Mihai, I.; Petrascu, H.; Rudchik, A. T.; Chernievski, V. A.; Ponkratenko, O. A.; Ziman, V. A.

    1993-12-01

    The energy spectra and angular distributions of products in the reaction27Al(14N, X) have been measured at 116 MeV bombarding energy. It is shown that the energy spectra of the products lighter than the projectile, are well described by a three-body breakup calculation. The experimental total breakup cross-section estimated in the present work, together with Glas-Mosel calculation of the fusion cross-section, are in a reasonable agreement with the optical model total reaction cross-section.

  13. Reaction mechanism in the {sup 16}O+{sup 27}Al system: Measurements and analysis of excitation functions and angular distributions

    SciTech Connect

    Sharma, Manoj Kumar; Unnati,; Singh, Devendra P.; Singh, Pushpendra P.; Singh, B. P.; Prasad, R.; Bhardwaj, H. D.

    2007-06-15

    To study the dynamics of heavy ion fusion reactions in the lower mass region, experiments were carried out to measure the cross sections of radioactive residues produced in the interaction of the {sup 16}O ion with {sup 27}Al target nucleus at 19 different energies in very close intervals covering the energy range from {approx_equal}58 to 94 MeV, using the well-known recoil catcher off-line {gamma}-ray spectroscopy technique. The simulation of experimental data was performed using statistical-model-based computer codes, viz., CASCADE, PACE2, and ALICE-91. The analysis of measured excitation functions indicates that these residues are likely to be produced by complete fusion, incomplete fusion, and direct reaction processes. Furthermore, to confirm the contribution of different reaction channels, a complementary experiment was performed that measured the angular distributions of the residues produced in the {sup 16}O+{sup 27}Al system at 85 MeV beam energy. The analysis of the results of both experiments indicates that at these energies, the direct reactions compete with complete fusion and incomplete fusion reaction processes.

  14. Dissociative recombination of N2H+

    NASA Astrophysics Data System (ADS)

    dos Santos, S. Fonseca; Ngassam, V.; Orel, A. E.; Larson, Å.

    2016-08-01

    The direct and indirect mechanisms of dissociative recombination of N2H+ are theoretically studied. At low energies, the electron capture is found to be driven by recombination into bound Rydberg states, while at collision energies above 0.1 eV, the direct capture and dissociation along electronic resonant states becomes important. Electron-scattering calculations using the complex Kohn variational method are performed to obtain the scattering matrix as well as energy positions and autoionization widths of resonant states. Potential-energy surfaces of electronic bound states of N2H and N2H+ are computed using structure calculations with the multireference configuration interaction method. The cross section for the indirect mechanism is calculated using a vibrational frame transformation of the elements of the scattering matrix at energies just above the ionization threshold. Here vibrational excitations of the ionic core from v =0 to v =1 and v =2 for all three normal modes are considered and autoionization is neglected. The cross section for the direct dissociation along electronic resonant states is computed with wave-packet calculations using the multiconfiguration time-dependent Hartree method, where all three internal degrees of freedom are considered. The calculated cross sections are compared to measurements.

  15. 2H-DNP-enhanced 2H–13C solid-state NMR correlation spectroscopy

    PubMed Central

    Maly, Thorsten; Andreas, Loren B.; Smith, Albert A.

    2015-01-01

    Perdeuteration of biological macromolecules for magic angle spinning solid-state NMR spectroscopy can yield high-resolution 2H–13C correlation spectra and the method is therefore of great interest for the structural biology community. Here we demonstrate that the combination of sample deuteration and dynamic nuclear polarization yields resolved 2H–13C correlation spectra with a signal enhancement of ε ≥ 700 compared to a spectrum recorded with microwaves off and otherwise identical conditions. To our knowledge, this is the first time that 2H-DNP has been employed to enhance MAS-NMR spectra of a biologically relevant system. The DNP process is studied using several polarizing agents and the technique is applied to obtain 2H–13C correlation spectra of U-[2H, 13C] proline. PMID:20458422

  16. 48 CFR 538.272 - MAS price reductions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false MAS price reductions. 538... Schedules 538.272 MAS price reductions. (a) Section 552.238-75, Price Reductions, requires the contractor to maintain during the contract period the negotiated price/discount relationship (and/or term and...

  17. 48 CFR 538.272 - MAS price reductions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false MAS price reductions. 538... Schedules 538.272 MAS price reductions. (a) Section 552.238-75, Price Reductions, requires the contractor to maintain during the contract period the negotiated price/discount relationship (and/or term and...

  18. 48 CFR 538.272 - MAS price reductions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false MAS price reductions. 538... Schedules 538.272 MAS price reductions. (a) Section 552.238-75, Price Reductions, requires the contractor to maintain during the contract period the negotiated price/discount relationship (and/or term and...

  19. 48 CFR 538.272 - MAS price reductions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false MAS price reductions. 538... Schedules 538.272 MAS price reductions. (a) Section 552.238-75, Price Reductions, requires the contractor to maintain during the contract period the negotiated price/discount relationship (and/or term and...

  20. Study on ethyl groups with two different orientations in [N(C2H5)4]2CuBr4

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran

    2016-06-01

    The crystal structure and phase transition temperature of [N(C2H5)4]2CuBr4 are studied using X-ray diffraction and differential scanning calorimetry (DSC); measurements revealed a tetragonal structure and the two phase transition temperatures TC of 204 K and 255.5 K. The structural geometry near TC is discussed in terms of the chemical shifts for 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) and 13C cross-polarization (CP)/MAS NMR. The two inequivalent ethyl groups are distinguishable by the 13C NMR spectrum. The molecular motions are discussed in terms of the spin-lattice relaxation times T1ρ in the rotating frame for 1H MAS NMR and 13C CP/MAS NMR. The T1ρ results reveal that the ethyl groups undergo tumbling motion, and furthermore that the ethyl groups are highly mobile.

  1. Inverse Kinematic Study of the Alg26(d ,p )27Al Reaction and Implications for Destruction of 26Al in Wolf-Rayet and Asymptotic Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    Margerin, V.; Lotay, G.; Woods, P. J.; Aliotta, M.; Christian, G.; Davids, B.; Davinson, T.; Doherty, D. T.; Fallis, J.; Howell, D.; Kirsebom, O. S.; Mountford, D. J.; Rojas, A.; Ruiz, C.; Tostevin, J. A.

    2015-08-01

    In Wolf-Rayet and asymptotic giant branch (AGB) stars, the Alg26(p ,γ )27Si reaction is expected to govern the destruction of the cosmic γ -ray emitting nucleus 26Al. The rate of this reaction, however, is highly uncertain due to the unknown properties of key resonances in the temperature regime of hydrogen burning. We present a high-resolution inverse kinematic study of the Alg26(d ,p )27Al reaction as a method for constraining the strengths of key astrophysical resonances in the Alg26(p ,γ )27Si reaction. In particular, the results indicate that the resonance at Er=127 keV in 27Si determines the entire Alg26(p ,γ )27Si reaction rate over almost the complete temperature range of Wolf-Rayet stars and AGB stars.

  2. Commissioning of the NPDGamma Detector Array: Counting Statistics in Current Mode Operation and Parity Violation in the Capture of Cold Neutrons on B4C and 27Al

    PubMed Central

    Gericke, M. T.; Bowman, J. D.; Carlini, R. D.; Chupp, T. E.; Coulter, K. P.; Dabaghyan, M.; Desai, D.; Freedman, S. J.; Gentile, T. R.; Gillis, R. C.; Greene, G. L.; Hersman, F. W.; Ino, T.; Ishimoto, S.; Jones, G. L.; Lauss, B.; Leuschner, M. B.; Losowski, B.; Mahurin, R.; Masuda, Y.; Mitchell, G. S.; Muto, S.; Nann, H.; Page, S. A.; Penttila, S. I.; Ramsay, W. D.; Santra, S.; Seo, P.-N.; Sharapov, E. I.; Smith, T. B.; Snow, W. M.; Wilburn, W. S.; Yuan, V.; Zhu, H.

    2005-01-01

    The NPDGamma γ-ray detector has been built to measure, with high accuracy, the size of the small parity-violating asymmetry in the angular distribution of gamma rays from the capture of polarized cold neutrons by protons. The high cold neutron flux at the Los Alamos Neutron Scattering Center (LANSCE) spallation neutron source and control of systematic errors require the use of current mode detection with vacuum photodiodes and low-noise solid-state preamplifiers. We show that the detector array operates at counting statistics and that the asymmetries due to B4C and 27Al are zero to with- in 2 × 10−6 and 7 × 10−7, respectively. Boron and aluminum are used throughout the experiment. The results presented here are preliminary. PMID:27308124

  3. Constraining 17O and 27Al NMR spectra of high-pressure crystals and glasses: New data for jadeite, pyrope, grossular, and mullite

    USGS Publications Warehouse

    Kelsey, K.E.; Stebbins, J.F.; Du, L.-S.; Hankins, B.

    2007-01-01

    The 17O NMR spectra of glasses quenched from melts at high pressure are often difficult to interpret due to overlapping peaks and lack of crystalline model compounds. High-pressure aluminosilicate glasses often contain significant amounts of [5]Al and [6]Al, thus these high-pressure glasses must contain oxygen bonded to high-coordinated aluminum. The 17O NMR parameters for the minerals jadeite, pyrope, grossular, and mullite are presented to assist interpretation of glass spectra and to help test quantum chemical calculations. The 17O NMR parameters for jadeite and grossular support previous peak assignments of oxygen bonded to Si and high-coordinated Al in high-pressure glasses as well as quantum chemical calculations. The oxygen tricluster in mullite is very similar to the previously observed tricluster in grossite (CaAl4 O7) and suspected triclusters in glasses. We also present 27Al NMR spectra for pyrope, grossular, and mullite.

  4. Single crystal 27Al-NMR study of the cubic Γ3 ground doublet system PrTi2Al20

    NASA Astrophysics Data System (ADS)

    Taniguchi, T.; Yoshida, M.; Takeda, H.; Takigawa, M.; Tsujimoto, M.; Sakai, A.; Matsumoto, Y.; Nakatsuji, S.

    2016-02-01

    We report results of 27Al-NMR measurements on a single crystal of PrTi2Al20, in which the ground state of Pr3+ ions in the crystalline electric field is the nonmagneitc Γ3 doublet. From the analysis of NMR spectra with the magnetic field applied precisely along the ⟨111⟩ and ⟨100⟩ directions, we determined the electric field gradient tensors for all three inequivalent Al sites (Al(1) ∼ Al(3) sites) and the anisotropic Knight shifts for the Al(3) sites. The hyperfine coupling tensor at the Al(3) sites is strongly anisotropic and much larger than the classical dipolar coupling, indicating importance of the anisotropic hybridization between the conduction and ƒ electron states.

  5. Synthesis Of [2h, 13c] And [2h3, 13c]Methyl Aryl Sulfides

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2004-03-30

    The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2,.sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms. The present invention is also directed to the labeled compounds of [.sup.2 H.sub.1, .sup.13 C]methyl iodide and [.sup.2 H.sub.2, .sup.13 C]methyl iodide.

  6. Measurement and analysis of energy and angular distributions of thick target neutron yields from 110 MeV {sup 19}F on {sup 27}Al

    SciTech Connect

    Sunil, C.; Nandy, Maitreyee; Sarkar, P. K.

    2008-12-15

    Energy distributions of emitted neutrons were measured for 110 MeV {sup 19}F ions incident on a thick {sup 27}Al target. Measurements were done at 0 deg., 30 deg., 60 deg., 90 deg., and 120 deg. with respect to the projectile direction employing the time-of-flight technique using a proton recoil scintillation detector. Comparison with calculated results from equilibrium nuclear reaction model codes like PACE-2 and EMPIRE 2.18 using various level-density options was carried out. It is observed that the dynamic level-density approach in EMPIRE 2.18 gives the closest approximation to the measured data. In the Fermi-gas level-density approach the best approximation of the level-density parameter is a=A/12.0, where A is the mass number of the composite system. The trend in the angular distribution of emitted neutrons is well reproduced by the projection of the angular momentum on the recoil axis as done in the PACE-2 code.

  7. Observation of the {sup 1}S{sub 0}{yields}{sup 3}P{sub 0} Clock Transition in {sup 27}Al{sup +}

    SciTech Connect

    Rosenband, T.; Schmidt, P. O.; Hume, D. B.; Itano, W. M.; Stalnaker, J. E.; Kim, K.; Diddams, S. A.; Koelemeij, J. C. J.; Bergquist, J. C.; Wineland, D. J.; Fortier, T. M.

    2007-06-01

    We report, for the first time, laser spectroscopy of the {sup 1}S{sub 0}{yields}{sup 3}P{sub 0} clock transition in {sup 27}Al{sup +}. A single aluminum ion and a single beryllium ion are simultaneously confined in a linear Paul trap, coupled by their mutual Coulomb repulsion. This coupling allows the beryllium ion to sympathetically cool the aluminum ion and also enables transfer of the aluminum's electronic state to the beryllium's hyperfine state, which can be measured with high fidelity. These techniques are applied to measure the clock transition frequency {nu}=1 121 015 393 207 851(6) Hz. They are also used to measure the lifetime of the metastable clock state {tau}=20.6{+-}1.4 s, the ground state {sup 1}S{sub 0} g factor g{sub S}=-0.000 792 48(14), and the excited state {sup 3}P{sub 0} g factor g{sub P}=-0.001 976 86(21), in units of the Bohr magneton.

  8. [sup 31]P and [sup 27]Al NMR investigations of the effects of pH on aqueous solutions containing aluminum and phosphorus

    SciTech Connect

    Mortlock, R.F.; Bell, A.T.; Radke, C.J. Univ. of California, Berkeley )

    1993-01-21

    [sup 31]P and [sup 27]Al NMR spectroscopies are used to characterize the distribution of soluble aluminophosphate species in aqueous solutions of tetramethylammonium (TMA) hydroxide, phosphoric acid, and aluminum chloride. Solution compositions range from 0.1 to 1 mol % P, P/Al = 0.1-5, P/(TMA)[sub 2]O = 0.37-10. For solutions of 1 mol % P, a phase diagram is constructed for various concentrations of TMAOH and Al. The phase diagram is divided into three regions: a high-pH region (pH [ge] 6), a medium-pH range (2 [le] pH [le] 10) in which stable solid phases exist, and a low-pH region (pH [le] 2). In the low-pH region, soluble aluminophosphate complexes form between P species (H[sub 3]PO[sub 4] acid dimers, H[sub 3]PO[sub 4] molecules, and H[sub 2]PO[sub 4][sup [minus

  9. Influence of heat treatment on the microstructure and wear behavior of end-chill cast Zn-27Al alloys with different copper content

    NASA Astrophysics Data System (ADS)

    Jeshvaghani, R. Arabi; Ghahvechian, H.; Pirnajmeddin, H.; Shahverdi, H. R.

    2016-04-01

    The aim of this paper was to study the effect of heat treatment on the microstructure and wear behavior of Zn-27Al alloys with different copper content. In order to study the relationship between microstructure features and wear behavior, the alloys prepared by an end-chill cast apparatus and then heat treated. Heat treatment procedure involved solutionizing at temperature of 350 °C for 72 h followed by cooling within the furnace to room temperature. Microstructural characteristics of as-cast and heat-treated alloys at different distances from the chill were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction. Wear tests were performed using a pin-on-disk test machine. To determine the wear mechanisms, the worn surfaces of the samples were also examined by SEM and EDS. Results showed that heat treatment led to the complete dissolution of as-cast dendritic microstructure and formation of a fine lamellar structure with well-distributed microconstituents. Moreover, addition of copper up to 1 wt% had no significant change in the microstructure, while addition of 2 and 4 wt% copper resulted in formation of ɛ (CuZn4) particle in the interdendritic regions. The influence of copper content on the wear behavior of the alloys was explained in terms of microstructural characteristics. Delamination was proposed as the dominant wear mechanism.

  10. SCAM-STMAS: satellite-transition MAS NMR of quadrupolar nuclei with self-compensation for magic-angle misset

    NASA Astrophysics Data System (ADS)

    Ashbrook, Sharon E.; Wimperis, Stephen

    2003-06-01

    Several methods are available for the acquisition of high-resolution solid-state NMR spectra of quadrupolar nuclei with half-integer spin quantum number. Satellite-transition MAS (STMAS) offers an approach that employs only conventional MAS hardware and can yield substantial signal enhancements over the widely used multiple-quantum MAS (MQMAS) experiment. However, the presence of the first-order quadrupolar interaction in the satellite transitions imposes the requirement of a high degree of accuracy in the setting of the magic angle on the NMR probehead. The first-order quadrupolar interaction is only fully removed if the sample spinning angle, χ, equals cos-1(1/ 3) exactly and rotor synchronization is performed. The required level of accuracy is difficult to achieve experimentally, particularly when the quadrupolar interaction is large. If the magic angle is not set correctly, the first-order splitting is reintroduced and the spectral resolution is severely compromised. Recently, we have demonstrated a novel STMAS method (SCAM-STMAS) that is self-compensated for angle missets of up to ±1° via coherence transfer between the two different satellite transitions ST +( mI=+3/2↔+1/2) and ST -( mI=-1/2↔-3/2) midway through the t1 period. In this work we describe in more detail the implementation of SCAM-STMAS and demonstrate its wider utility through 23Na ( I=3/2), 87Rb ( I=3/2), 27Al ( I=5/2), and 59Co ( I=7/2) NMR. We discuss linewidths in SCAM-STMAS and the limits over which angle-misset compensation is achieved and we demonstrate that SCAM-STMAS is more tolerant of temporary spinning rate fluctuations than STMAS, resulting in less " t1 noise" in the two-dimensional spectrum. In addition, alternative correlation experiments, for example involving the use of double-quantum coherences, that similarly display self-compensation for angle misset are investigated. The use of SCAM-STMAS is also considered in systems where other high-order interactions, such as third

  11. Structural biology applications of solid state MAS DNP NMR.

    PubMed

    Akbey, Ümit; Oschkinat, Hartmut

    2016-08-01

    Dynamic Nuclear Polarization (DNP) has long been an aim for increasing sensitivity of nuclear magnetic resonance (NMR) spectroscopy, delivering spectra in shorter experiment times or of smaller sample amounts. In recent years, it has been applied in magic angle spinning (MAS) solid-state NMR to a large range of samples, including biological macromolecules and functional materials. New research directions in structural biology can be envisaged by DNP, facilitating investigations on very large complexes or very heterogeneous samples. Here we present a summary of state of the art DNP MAS NMR spectroscopy and its applications to structural biology, discussing the technical challenges and factors affecting DNP performance. PMID:27095695

  12. MAS PFG NMR Studies of Mixtures in Porous Materials

    NASA Astrophysics Data System (ADS)

    Gratz, Marcel; Hertel, Stefan; Wehring, Markus; Schlayer, Stefan; Stallmach, Frank; Galvosas, Petrik

    2011-03-01

    Pulsed field gradient (PFG) and magic angle spinning (MAS) NMR techniques have been successfully combined for the study of mixture diffusion in porous materials. Using a modular setup of commercially available components, gradient pulses of up to ±2.6 T/m can be applied coinciding with fast sample rotation at the magic angle. Methods for the proper alignment of all components are presented along with protocols for MAS PFG NMR experiments. Finally, first diffusion measurements of n-hexane and benzene being adsorbed together in the metal-organic framework MOF-5 are presented.

  13. MAS2-8 radar and digital control unit

    NASA Technical Reports Server (NTRS)

    Oberg, J. M.; Ulaby, F. T.

    1974-01-01

    The design of the MAS 2-8 (2 to 8 GHz microwave-active spectrometer), a ground-based sensor system, is presented. A major modification in 1974 to the MAS 2-8, that of a control subsystem to automate the data-taking operation, is the prime focus. The digital control unit automatically changes all system parameters except FM rate and records the return signal on paper tape. The overall system operation and a detailed discussion of the design and operation of the digital control unit are presented.

  14. Structural biology applications of solid state MAS DNP NMR

    NASA Astrophysics Data System (ADS)

    Akbey, Ümit; Oschkinat, Hartmut

    2016-08-01

    Dynamic Nuclear Polarization (DNP) has long been an aim for increasing sensitivity of nuclear magnetic resonance (NMR) spectroscopy, delivering spectra in shorter experiment times or of smaller sample amounts. In recent years, it has been applied in magic angle spinning (MAS) solid-state NMR to a large range of samples, including biological macromolecules and functional materials. New research directions in structural biology can be envisaged by DNP, facilitating investigations on very large complexes or very heterogeneous samples. Here we present a summary of state of the art DNP MAS NMR spectroscopy and its applications to structural biology, discussing the technical challenges and factors affecting DNP performance.

  15. Cation distribution in co-doped ZnAl2O4 nanoparticles studied by X-ray photoelectron spectroscopy and 27Al solid-state NMR spectroscopy.

    PubMed

    Duan, Xiulan; Yuan, Duorong; Yu, Fapeng

    2011-06-20

    Co(x)Zn(1-x)Al(2)O(4) (x = 0.01-0.6) nanoparticles were synthesized by the citrate sol-gel method and were characterized by X-ray powder diffraction and transmission electron microscopy to identify the crystalline phase and determine the particle size. X-ray photoelectron spectroscopy and (27)Al solid-state NMR spectroscopy were used to study the distribution of the cations in the tetrahedral and octahedral sites in Co(x)Zn(1-x)Al(2)O(4) nanoparticles as a function of particle size and composition. The results show that all of the as-synthesized samples exhibit spinel-type single phase; the crystallite size of the samples is about 20-50 nm and increases with increasing annealing temperature and decreases with Co-enrichment. Zn(2+) ions are located in large proportions in the tetrahedral sites and in small proportions in the octahedral sites in Co(x)Zn(1-x)Al(2)O(4) nanoparticles. The fraction of octahedral Zn(2+) increases with increasing Co concentration and decreases with increasing particle size. Besides the tetrahedral and octahedral coordinations, the presence of the second octahedrally coordinated Al(3+) ions is observed in the nanoparticles. The change of the inversion parameter (2 times the fraction of Al(3+) ions in tetrahedral sites) with Co concentration and particle size is consistent with that of the Zn fraction in octahedral sites. Analysis of the absorption properties indicates that Co(2+) ions are located in the tetrahedral sites as well as in the octahedral sites in the nanoparticles. The inversion degree of Co(2+) decreases with increasing particle size. PMID:21612229

  16. Constraints on the structure and dynamics of the β-cristobalite polymorphs of SiO2 and AlPO4 from 31P, 27Al and 29Si NMR spectroscopy to 770 K

    NASA Astrophysics Data System (ADS)

    Phillips, Brian L.; Thompson, John G.; Xiao, Yuehui; Kirkpatrick, R. James

    1993-10-01

    Nuclear magnetic resonance spectroscopic data are presented for the cristobalite polymorphs of AlPO4 and SiO2 from RT to 770 K, through their respective α- β transitions. The nuclear magnetic resonance (NMR) data include chemical shifts for 31P, 27Al, and 29Si, 27Al quadrupole coupling parameters, and 31P and 27Al spin-lattice relaxation rates. Also presented are electron diffraction patterns of β-cristobalite AlPO4 that show diffuse scattering similar to that reported previously for SiO2. For the α-phases of both AlPO4 and SiO2, the chemical shifts decrease approximately linearly with increasing temperature from RT to Tc and discontinuously by -2 to -3 ppm from α to β. This result is consistent with a small, continuous increase in the mean T-O-T angle (<θ>) of the α-phases with increasing T and an increase of <θ> by about 4° across the α- β transition for both cristobalite and its AlPO4 analogue. Based on the 29Si chemical shifts, the mean Si-O-Si angle for β-cristobalite is 152.7±1° near Tc. For AlPO4-cristobalite, the 27Al nuclear quadrupole coupling constant (CQ) decreases approximately linearly from 1.2 MHz at RT to 0.94 MHz near Tc (493±10 K). At the α- β transition the 27Al CQ approaches zero, in agreement with the cubic average structure observed by diffraction. The satellite transitions retain a small frequency distribution above the α- β transition from electric field gradients attributed to defects. The short-range cubic symmetry of the Al-site and non-linear Al-O-P angle support a dynamically disordered model of the β-cristobalite structure. Complete averaging of the 27Al quadrupole coupling in the β-phase indicates that the lifetime of any short-range ordered domains must be shorter than about 1 μs.

  17. Rate Coefficients of C2H with C2H4, C2H6, and H2 from 150 to 359 K

    NASA Technical Reports Server (NTRS)

    Opansky, Brian J.; Leone, Stephen R.

    1996-01-01

    Rate coefficients for the reactions C2H with C2H4, C2H6, and H2 are measured over the temperature range 150-359 K using transient infrared laser absorption spectroscopy. The ethynyl radical is formed by photolysis of C2H2 with a pulsed excimer laser at 193 nm, and its transient absorption is monitored with a color center laser on the Q(sub 11)(9) line of the A(sup 2) Pi-Chi(sup 2) Sigma transition at 3593.68 cm(exp -1). Over the experimental temperature range 150-359 K the rate constants of C2H with C2H4, C2H6, and H2 can be fitted to the Arrhenius expressions k(sub C2H4) = (7.8 +/- 0.6) x 10(exp -11) exp[(134 +/- 44)/T], k(sub C2H6) = (3.5 +/- 0.3) x 10(exp -11) exp[(2.9 +/- 16)/T], and k(sub H2) = (1.2 +/- 0.3) x 10(exp -11) exp[(-998 +/- 57)]/T cm(exp 3) molecule(exp -1) sec(exp -1). The data for C2H with C2H4 and C2H6 indicate a negligible activation energy to product formation shown by the mild negative temperature dependence of both reactions. When the H2 data are plotted together with the most recent high-temperature results from 295 to 854 K, a slight curvature is observed. The H2 data can be fit to the non-Arrhenius form k(sub H2) = 9.2 x 10(exp -18) T(sup 2.17 +/- 0.50) exp[(-478 +/- 165)/T] cm(exp 3) molecules(exp -1) sec(exp -1). The curvature in the Arrhenius plot is discussed in terms of both quantum mechanical tunneling of the H atom from H2 to the C2H radical and bending mode contributions to the partition function.

  18. Nuclear magnetic resonance study of the ferroelastic phase transition of order-disorder type in [N(C2H5)4]2CdCl4

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran; Kim, Min Soo; Lim, Kye-Young

    2016-08-01

    This study uses nuclear magnetic resonance (NMR) techniques to examine the detailed changes in [N(C2H5)4]2CdCl4 around its phase transition at the temperature TC = 284 K. The chemical shifts and spin-lattice relaxation times in the rotating frame (T1ρ) were determined from 1H magic angle spinning (MAS) NMR and 13C cross-polarization (CP)/MAS NMR spectra. The two sets of inequivalent 1H and 13C nuclei in CH3 and CH2 were distinguished. A ferroelastic phase transition was observed at TC, without structural symmetry change. The phase transition is mainly attributed to the orientational ordering of the [N(C2H5)4]+ cations, and the spectral splitting at low temperature is associated with different ferroelastic domains.

  19. Draft Genome Sequence of Geobacillus thermopakistaniensis Strain MAS1

    PubMed Central

    Rashid, Naeem; Ayyampalayam, Saravanaraj

    2014-01-01

    Geobacillus thermopakistaniensis strain MAS1 was isolated from a hot spring located in the Northern Areas of Pakistan. The draft genome sequence was 3.5 Mb and identified a number of genes of potential industrial importance, including genes encoding glycoside hydrolases, pullulanase, amylopullulanase, glycosidase, and alcohol dehydrogenases. PMID:24903880

  20. Draft Genome Sequence of Geobacillus thermopakistaniensis Strain MAS1.

    PubMed

    Siddiqui, Masood Ahmed; Rashid, Naeem; Ayyampalayam, Saravanaraj; Whitman, William B

    2014-01-01

    Geobacillus thermopakistaniensis strain MAS1 was isolated from a hot spring located in the Northern Areas of Pakistan. The draft genome sequence was 3.5 Mb and identified a number of genes of potential industrial importance, including genes encoding glycoside hydrolases, pullulanase, amylopullulanase, glycosidase, and alcohol dehydrogenases. PMID:24903880

  1. Resolution and polarization distribution in cryogenic DNP/MAS experiments

    PubMed Central

    Barnes, Alexander B.; Corzilius, Björn; Mak-Jurkauskas, Melody L.; Andreas, Loren B.; Bajaj, Vikram S.; Matsuki, Yoh; Belenky, Marina L.; Lugtenburg, Johan; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Herzfeld, Judith; Griffin, Robert G.

    2014-01-01

    This contribution addresses four potential misconceptions associated with high-resolution dynamic nuclear polarization/magic angle spinning (DNP/MAS) experiments. First, spectral resolution is not generally compromised at the cryogenic temperatures at which DNP experiments are performed. As we demonstrate at a modest field of 9 T (380 MHz 1H), 1 ppm linewidths are observed in DNP/MAS spectra of a membrane protein in its native lipid bilayer, and <0.4 ppm linewidths are reported in a crystalline peptide at 85 K. Second, we address the concerns about paramagnetic broadening in DNP/MAS spectra of proteins by demonstrating that the exogenous radical polarizing agents utilized for DNP are distributed in the sample in such a manner as to avoid paramagnetic broadening and thus maintain full spectral resolution. Third, the enhanced polarization is not localized around the polarizing agent, but rather is effectively and uniformly dispersed throughout the sample, even in the case of membrane proteins. Fourth, the distribution of polarization from the electron spins mediated via spin diffusion between 1H–1H strongly dipolar coupled spins is so rapid that shorter magnetization recovery periods between signal averaging transients can be utilized in DNP/MAS experiments than in typical experiments performed at ambient temperature. PMID:20454732

  2. Quantitation of methadone enantiomers in humans using stable isotope-labeled (2H3)-, (2H5)-, and (2H8)Methadone

    SciTech Connect

    Nakamura, K.; Hachey, D.L.; Kreek, M.J.; Irving, C.S.; Klein, P.D.

    1982-01-01

    A new technique for simultaneous stereoselective kinetic studies of methadone enantiomers was developed using three deuterium-labeled forms of methadone and GLC-chemical-ionization mass spectrometry. A racemic mixture (1:1) of (R)-(-)-(2H5)methadone (l-form) and (S)-(R)-(2H3)methadone (d-form) was administered orally in place of a single daily dose of unlabeled (+/-)-(2H0)methadone in long-term maintenance patients. Racemic (+/-)-(2H8)methadone was used as an internal standard for the simultaneous quantitation of (2H0)-, (2H3)-, and (2H5)methadone in plasma and urine. A newly developed extraction procedure, using a short, disposable C18 reversed-phase cartridge and improved chemical-ionization procedures employing ammonia gas, resulted in significant reduction of the background impurities contributing to the ions used for isotopic abundance measurements. These improvements enabled the measurement of labeled plasma methadone levels for 120 hr following a single dose. This methodology was applied to the study of methadone kinetics in two patients; in both patients, the analgesically active l-enantiomer of the drug had a longer plasma elimination half-life and a smaller area under the plasma disappearance curve than did the inactive d-form.

  3. Adiabatic hyperspherical study of weakly bound He(2)H(-), He(2)H, and HeH(2) systems.

    PubMed

    Suno, Hiroya

    2010-06-14

    The He(2)H(-), He(2)H, and HeH(2) triatomic systems are studied using the adiabatic hyperspherical representation. By adopting the best empirical interaction potentials, we search for weakly bound states of (4)He(2) H(-), (4)He(2) H, and (4)HeH(2). We consider not only zero total nuclear orbital angular momentum, J=0, states but also J>0 states. We find no bound state for the (4)He(2) H systems, while the (4)He(2) H(-) and (4)HeH(2) systems are shown to possess three and one bound states, respectively, for J(Pi)=0(+). Interestingly, one bound state has been found each for the J(Pi)=1(-) and 2(+) symmetries of the (4)He(2) H(-) anion. We shall calculate the bound state energies and analyze the molecular structure of these species in detail. PMID:20550401

  4. Formation of Al2H7- anions--indirect evidence of volatile AlH3 on sodium alanate using solid-state NMR spectroscopy.

    PubMed

    Felderhoff, Michael; Zibrowius, Bodo

    2011-10-14

    After more than a decade of intense research on NaAlH(4) doped with transition metals as hydrogen storage material, the actual mechanism of the decomposition and rehydrogenation reaction is still unclear. Early on, monomeric AlH(3) was named as a possible transport shuttle for aluminium, but never observed experimentally. Here we report for the first time the trapping of volatile AlH(3) produced during the decomposition of undoped NaAlH(4) by an adduct of sodium alanate and crown ether. The resulting Al(2)H(7)(-) anion was identified by solid-state (27)Al NMR spectroscopy. Based on this indirect evidence of volatile alane, we present a simple description of the processes occurring during the reversible dehydrogenation of NaAlH(4). PMID:21879065

  5. Direct Detection of Supramolecular Reaction Centers in the Methanol-to-Olefins Conversion over Zeolite H-ZSM-5 by (13)C-(27)Al Solid-State NMR Spectroscopy.

    PubMed

    Wang, Chao; Wang, Qiang; Xu, Jun; Qi, Guodong; Gao, Pan; Wang, Weiyu; Zou, Yunyun; Feng, Ningdong; Liu, Xiaolong; Deng, Feng

    2016-02-12

    Hydrocarbon-pool chemistry is important in methanol to olefins (MTO) conversion on acidic zeolite catalysts. The hydrocarbon-pool (HP) species, such as methylbenzenes and cyclic carbocations, confined in zeolite channels during the reaction are essential in determining the reaction pathway. Herein, we experimentally demonstrate the formation of supramolecular reaction centers composed of organic hydrocarbon species and the inorganic zeolite framework in H-ZSM-5 zeolite by advanced (13)C-(27)Al double-resonance solid-state NMR spectroscopy. Methylbenzenes and cyclic carbocations located near Brønsted acid/base sites form the supramolecular reaction centers in the zeolite channel. The internuclear spatial interaction/proximity between the (13)C nuclei (associated with HP species) and the (27) Al nuclei (associated with Brønsted acid/base sites) determines the reactivity of the HP species. The closer the HP species are to the zeolite framework Al, the higher their reactivity in the MTO reaction. PMID:26732748

  6. Study of the ferroelastic phase transition in the tetraethylammonium compound [N(C2H5)4]2ZnBr4 by magic-angle spinning and static NMR

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran

    2016-03-01

    The ferroelastic phase transition of tetraethylammonium compound [N(C2H5)4]2ZnBr4 at the phase transition temperature (TC) = 283 K was characterized by magic-angle spinning (MAS) and static nuclear magnetic resonance (NMR), and confirmed by optical polarizing spectroscopy. The structural geometry near TC was studied in terms of the chemical shifts and the spin-lattice relaxation times T1ρ in the rotating frame for 1H MAS NMR and 13C cross-polarization (CP)/MAS NMR. The two inequivalent ethyl groups were distinguishable in the 13C NMR spectrum, and the T1ρ results indicate that they undergo tumbling motion above TC in a coupled manner. From the 14N NMR results, the two nitrogen nuclei in the N(C2H5)4+ ions were distinguishable above TC, and the splitting in the spectra below TC was related to the ferroelastic domains with different orientations.

  7. Synthesis Of [2h, 13c]M [2h2m 13c], And [2h3,, 13c] Methyl Aryl Sulfones And Sulfoxides

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.; Schmidt, Jurgen G.

    2004-07-20

    The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfones and [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfoxides, wherein the .sup.13 C methyl group attached to the sulfur of the sulfone or sulfoxide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing methyl aryl sulfones and methyl aryl sulfoxides.

  8. McDonnell F2H-3 Banshee

    NASA Technical Reports Server (NTRS)

    1957-01-01

    McDonnell F2H-3 Banshee: To more clearly mark the operators of this McDonnell F2H-3 Banshee, the 'VY' of Navy has been painted out and the appropriate lettering to spell NACA has been applied. Note that the second 'A' is of a different shape than the first. The 'Banjo' retained Navy titles on the wings, however.

  9. Coherence selection in double CP MAS NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Jen-Hsien; Chou, Fang-Chieh; Tzou, Der-Lii M.

    2008-11-01

    Applications of double cross-polarization (CP) magic-angle spinning (MAS) NMR spectroscopy, via 1H/ 15N and then 15N/ 13C coherence transfers, for 13C coherence selection are demonstrated on a 15N/ 13C-labeled N-acetyl-glucosamine (GlcNAc) compound. The 15N/ 13C coherence transfer is very sensitive to the settings of the experimental parameters. To resolve explicitly these parameter dependences, we have systematically monitored the 13C{ 15N/ 1H} signal as a function of the rf field strength and the MAS frequency. The data reveal that the zero-quantum coherence transfer, with which the 13C effective rf field is larger than that of the 15N by the spinning frequency, would give better signal sensitivity. We demonstrate in one- and two-dimensional double CP experiments that spectral editing can be achieved by tailoring the experimental parameters, such as the rf field strengths and/or the MAS frequency.

  10. Commercial facility site selection simulating based on MAS

    NASA Astrophysics Data System (ADS)

    Chao, Yi; Li, Qingquan; Zheng, Guizhou

    2008-10-01

    The location of commercial facility decides the benefit of the operator to a large degree. Existing location methods can express the static relationships between site selection result and location factors, but there still are some limites when express the dynamic and uncertain relationship between them. Hence, a dynamic, stochastic and forecastable location model should be built which can introduce the customer's behavior into the model and combine the macro pattern and micro spatial interaction. So the authors proposes Geosim-LM based on MAS. Geosim-LM has 3 kinds of agents, CustAgent, SiteAgent and GovAgent. They represent the customers, commercial fercilities and government. The land type, land price and traffic are the model environment. Then Geosim-LM is applied in the bank branches site evaluation and selection in Liwan district, Guangzhou. In existing bank branches site evaluation, there are 70% consistent in score grade between result of Geosim-LM after 200 round runing and actual rebust location. It proves the model is reliable and feasible. The conclusions can be get from the paper. MAS have advantages in location choice than existed methods. The result of Geosim-LM running can powerfully proves that building location model based on MAS is feasible.

  11. The MicroMAS CubeSat Mission

    NASA Astrophysics Data System (ADS)

    Cahoy, K.; Blackwell, W. J.; Allen, G.; Bury, M.; Efromson, R.; Galbraith, C.; Hancock, T.; Leslie, V.; Osaretin, I.; Retherford, L.; Scarito, M.; Shields, M.; Toher, D.; Wight, K.; Miller, D.; Marinan, A.; Paek, S.; Peters, E.; Schmidt, F. H.; Alvisio, B.; Wise, E.; Masterson, R.; Franzim Miranda, D.; Crail, C.; Kingsbury, R.; Souffrant, A.; Orrego, L.; Eslinger, G.; Nicholas, A.; Pong, C.

    2012-12-01

    The recently published Midterm Assessment of NASA's Implementation of the Decadal Survey finds that, "The nation's Earth observing system is beginning a rapid decline in capability as long-running missions end and key new missions are delayed, lost, or canceled. The projected loss of observing capability could have significant adverse consequences for science and society." In this presentation, we explore low-cost, mission-flexible, and rapidly deployable spaceborne sensors that can meet stringent performance requirements pervading the NASA Earth Science measurement programs, including especially the recommended NRC Decadal Survey missions. New technologies have enabled a novel approach toward this science observational goal, and in this paper we describe recent technology develop efforts to address the challenges above through the use of CubeSat radiometers. The Micro-sized Microwave Atmospheric Satellite (MicroMAS) is a 3U cubesat (30x10x10 cm, ~4kg) hosting a passive microwave spectrometer operating near the 118.75-GHz oxygen absorption line. The focus of the first MicroMAS mission (hereafter, MicroMAS-1) is to observe convective thunderstorms, tropical cyclones, and hurricanes from a near-equatorial orbit at approximately 500-km altitude. A MicroMAS flight unit is currently being developed in anticipation of a 2014 launch to be provided by NASA. A parabolic reflector is mechanically rotated as the spacecraft orbits the earth, thus directing a cross-track scanned beam with FWHM beamwidth of 2.4-degrees, yielding an approximately 25-km diameter footprint from a nominal altitude of 500 km. Radiometric calibration is carried out using observations of cold space, the earth's limb, and an internal noise diode that is weakly coupled through the RF front-end electronics. A key technology feature is the development of an ultra-compact intermediate frequency processor module for channelization, detection, and A-to-D conversion. The antenna system and RF front

  12. Determination of muscle protein synthesis rates in fish using (2)H2O and (2)H NMR analysis of alanine.

    PubMed

    Marques, Cátia; Viegas, Filipa; Rito, João; Jones, John; Viegas, Ivan

    2016-09-15

    Following administration of deuterated water ((2)H2O), the fractional synthetic rate (FSR) of a given endogenous protein can be estimated by (2)H-enrichment quantification of its alanine residues. Currently, this is measured by mass spectrometry following a derivatization procedure. Muscle FSR was measured by (1)H/(2)H NMR analysis of alanine from seabass kept for 6 days in 5% (2)H-enriched saltwater, following acid hydrolysis and amino acid isolation by cation-exchange chromatography of muscle tissue. The analysis is simple and robust, and provides precise measurements of excess alanine (2)H-enrichment in the 0.1-0.4% range from 50 mmol of alanine recovered from muscle protein. PMID:27418547

  13. Theoretical study of the bonding of Nb(2+) to CH2, C2H2, and C2H4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

    1991-01-01

    The bonding of Nb(2+) with CH2, C2H2, and C2H4 is studied by using electronic structure calculations that include high levels of electron correlation. The binding energy for NbCH2(2+) is in good agreement with the lower bound determined from the reaction with CH4 but is significantly smaller than the value determined from the binding energy and ionization potential of NbCH2(+). The calculations and a new interpretation of the experiment indicate that the larger value is in error primarily because the ionization potential of NbCH2(+) determined from bracketing charge-exchange reactions is too small. The computed binding energy of NbC2H2(2+) is in good agreement with experiment. The calculations show that the bonding is predominantly covalent in character for both NbCH2(2+) and NbC2H2(2+), whereas for NbC2H4(2+) the electronic states that are predominantly ionic and covalent are nearly degenerate. The trend in binding energies, CH2 greater than C2H2 greater than C2H4, is consistent with the energy required to prepare the ligands for bonding.

  14. C2H observations toward the Orion Bar

    NASA Astrophysics Data System (ADS)

    Nagy, Z.; Ossenkopf, V.; Van der Tak, F. F. S.; Faure, A.; Makai, Z.; Bergin, E. A.

    2015-06-01

    Context. The ethynyl radical (C2H) is one of the first radicals to be detected in the interstellar medium. Its higher rotational transitions have recently become available with the Herschel Space Observatory. Aims: We aim to constrain the physical parameters of the C2H emitting gas toward the Orion Bar. Methods: We analyze the C2H line intensities measured toward the Orion Bar CO+ Peak and Herschel/HIFI maps of C2H, CH, and HCO+ and a NANTEN map of [Ci]. We interpret the observed C2H emission using the combination of Herschel/HIFI and NANTEN data with radiative transfer and PDR models. Results: Five rotational transitions of C2H (from N = 6-5 up to N = 10-9) have been detected in the HIFI frequency range toward the CO+ peak of the Orion Bar. Based on the five detected C2H transitions, a single component rotational diagram analysis gives a rotation temperature of ~64 K and a beam-averaged C2H column density of 4 × 1013 cm-2. The rotational diagram is also consistent with a two-component fit, resulting in rotation temperatures of 43 ± 0.2 K and 123 ± 21 K and in beam-averaged column densities of ~8.3 × 1013 cm-2 and ~2.3 × 1013 cm-2 for the three lower-N and for the three higher-N transitions, respectively. The measured five rotational transitions cannot be explained by any single parameter model. According to a non-LTE model, most of the C2H column density produces the lower-N C2H transitions and traces a warm (Tkin ~ 100-150 K) and dense (n(H2) ~ 105-106 cm-3) gas. A small fraction of the C2H column density is required to reproduce the intensity of the highest-N transitions (N = 9-8 and N = 10-9) originating in a high-density (n(H2) ~5 × 106 cm-3) hot (Tkin ~ 400 K) gas. The total beam-averaged C2H column density in the model is 1014 cm-2. A comparison of the spatial distribution of C2H to those of CH, HCO+, and [Ci] shows the best correlation with CH. Conclusions: Both the non-LTE radiative transfer model and a simple PDR model representing the Orion Bar

  15. Milli-Arcsecond (MAS) Imaging of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Davila, Joseph M.; Oktem, Figen S.; Kamalabadi, Farzad; O'Neill, John; Novo-Gradac, Anne-Marie; Daw, Adrian N.; Rabin, Douglas M.

    2016-05-01

    Dissipation in the solar corona is believed to occur in extremely thin current sheets of order 1-100 km. Emission from these hot but thin current sheets should be visible in coronal EUV emission lines. However, this spatial scale is far below the resolution of existing imaging instruments, so these dissipation sites have never been observed individually. Conventional optics cannot be manufactured with sufficient surface figure accuracy to obtain the required spatial resolution in the extreme-ultraviolet where these hot plasmas radiate. A photon sieve, a diffractive imaging element similar to a Fresnel zone plate, can be manufactured to provide a few milli-arcsec (MAS) resolution, with much more readily achievable tolerances than with conventional imaging technology. Prototype photon sieve elements have been fabricated and tested in the laboratory. A full-scale ultra-high resolution instrument will require formation flying and computational image deconvolution. Significant progress has been made in overcoming these challenges, and some recent results in these areas are discussed. A simple design for a sounding rocket concept demonstration payload is presented that obtains 80 MAS (0.080 arcsec) imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and Fe XVI 335. These images will show the structure of the corona at a resolution never before obtained, and they will also allow a study of the temperature structure in the dissipation region.

  16. MAS C-Terminal Tail Interacting Proteins Identified by Mass Spectrometry- Based Proteomic Approach

    PubMed Central

    Tirupula, Kalyan C.; Zhang, Dongmei; Osbourne, Appledene; Chatterjee, Arunachal; Desnoyer, Russ; Willard, Belinda; Karnik, Sadashiva S.

    2015-01-01

    Propagation of signals from G protein-coupled receptors (GPCRs) in cells is primarily mediated by protein-protein interactions. MAS is a GPCR that was initially discovered as an oncogene and is now known to play an important role in cardiovascular physiology. Current literature suggests that MAS interacts with common heterotrimeric G-proteins, but MAS interaction with proteins which might mediate G protein-independent or atypical signaling is unknown. In this study we hypothesized that MAS C-terminal tail (Ct) is a major determinant of receptor-scaffold protein interactions mediating MAS signaling. Mass-spectrometry based proteomic analysis was used to comprehensively identify the proteins that interact with MAS Ct comprising the PDZ-binding motif (PDZ-BM). We identified both PDZ and non-PDZ proteins from human embryonic kidney cell line, mouse atrial cardiomyocyte cell line and human heart tissue to interact specifically with MAS Ct. For the first time our study provides a panel of PDZ and other proteins that potentially interact with MAS with high significance. A ‘cardiac-specific finger print’ of MAS interacting PDZ proteins was identified which includes DLG1, MAGI1 and SNTA. Cell based experiments with wild-type and mutant MAS lacking the PDZ-BM validated MAS interaction with PDZ proteins DLG1 and TJP2. Bioinformatics analysis suggested well-known multi-protein scaffold complexes involved in nitric oxide signaling (NOS), cell-cell signaling of neuromuscular junctions, synapses and epithelial cells. Majority of these protein hits were predicted to be part of disease categories comprising cancers and malignant tumors. We propose a ‘MAS-signalosome’ model to stimulate further research in understanding the molecular mechanism of MAS function. Identifying hierarchy of interactions of ‘signalosome’ components with MAS will be a necessary step in future to fully understand the physiological and pathological functions of this enigmatic receptor. PMID

  17. From molecular complexes to complex metallic nanostructures--2H solid-state NMR studies of ruthenium-containing hydrogenation catalysts.

    PubMed

    Gutmann, Torsten; del Rosal, Iker; Chaudret, Bruno; Poteau, Romuald; Limbach, Hans-Heinrich; Buntkowsky, Gerd

    2013-09-16

    In the last years, the combination of (2)H solid-state NMR techniques with quantum-chemical calculations has evolved into a powerful spectroscopic tool for the characterization of the state of hydrogen on the surfaces of heterogeneous catalysts. In the present minireview, a brief summary of this development is given, in which investigations of the structure and dynamics of hydrogen in molecular complexes, clusters and nanoparticle systems are presented, aimed to understand the reaction mechanisms on the surface of hydrogenation catalysts. The surface state of deuterium/hydrogen is analyzed employing a combination of variable-temperature (2)H static and magic-angle spinning (MAS) solid-state NMR techniques, in which the dominant quadrupolar interactions of deuterium give information on the binding situation and local symmetry of deuterium/hydrogen on molecular species. Using a correlation database from molecular complexes and clusters, the possibility to distinguish between terminal Ru-D, bridged Ru2-D, three-fold Ru3-D, and interstitial Ru6-D is demonstrated. Combining these results with quantum-chemical density functional theory (DFT) calculations allows the interpretation of (2)H solid-state data of complex "real world" nanostructures, which yielded new insights into reaction pathways at the molecular level. PMID:23658058

  18. Residual methyl protonation in perdeuterated proteins for multi-dimensional correlation experiments in MAS solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Agarwal, Vipin; Reif, Bernd

    2008-09-01

    NMR studies involving perdeuterated proteins focus in general on exchangeable amide protons. However, non-exchangeable sites contain as well a small amount of protons as the employed precursors for protein biosynthesis are not completely proton depleted. The degree of methyl group protonation is in the order of 9% for CD 2H using >97% deuterium enriched glucose. We show in this manuscript that this small amount of residual protonation is sufficient to perform 2D and 3D MAS solid-state NMR experiments. In particular, we suggest a HCCH-TOBSY type experiment which we successfully employ to assign the methyl resonances in aliphatic side chains in a perdeuterated sample of the SH3 domain of chicken α-spectrin.

  19. Meridional Variations of C2H2 and C2H6 in Jupiter's Atmosphere from Cassini CIRS Infrared Spectra

    NASA Technical Reports Server (NTRS)

    Nixon, C. A.; Achterberg, R. K.; Conrath, B. J.; Irwin, P. G. J.; Fouchet, T.; Parrish, P. D.; Romani, P. N.; Abbas, M.; LeClair, A.; Strobel, D.

    2004-01-01

    Hydrocarbons such as acetylene (C2H2) and ethane (C2H6) are important tracers in Jupiter's atmosphere, constraining our models of the chemical and dynamical processes. However, our knowledge of the vertical and meridional variations of their abundances has remained sparse. During the flyby of the Cassini spacecraft in December 2000, the Composite Infrared Spectrometer (CIRS) instrument was used to map the spatial variation of emissions from 10-1400 cm(sup -1) (1000-7 microns). In this paper we analyze a zonally-averaged set of CIRS spectra taken at the highest (0.5 cm(sup -1)) resolution, to infer atmospheric temperatures in the stratosphere at 0.5-20 mbar via the v4 band of CH4, and in the troposphere at 150-400 mbar, via the H2 absorption at 600-800 cm(sup -1). Simultaneously, we retrieve the abundances of C2H2 and C2H6 via the v5 and vg bands respectively. Tropospheric absorption and stratospheric emission are highly anti-correlated at the CIRS resolution, introducing a non-uniqueness into the retrievals, such that vertical gradient and column abundance cannot both be found without additional constraints. Assuming profile gradients from photochemical calculations, we show that the column abundance of C2H2 decreases sharply towards the poles by a factor approximately 4, while C2H6 is unchanged in the north and increasing in the south, by a factor approximately 1.8. An explanation for the meridional trends is proposed in terms of a combination of photochemistry and dynamics. Poleward, the decreasing UV flux is predicted to decrease the abundances of C2H2 and C2H6 by factors 2.7 and 3.5 respectively at a latitude 70 deg. However, the lifetime of C2H6 in the stratosphere (5 x 10(exp 9)) is much longer than the dynamical timescale for meridional motions inferred from SL-9 debris (5 x 10(exp 8 s)), and therefore the constant or rising abundance towards high latitudes likely indicates that meridional mixing dominates over photochemical effects. For C2H2, the opposite

  20. Angiotensin-(1-7)/Mas axis modulates fear memory and extinction in mice.

    PubMed

    Lazaroni, Thiago Luiz do Nascimento; Bastos, Cristiane Perácio; Moraes, Márcio Flávio Dutra; Santos, Robson Souza; Pereira, Grace Schenatto

    2016-01-01

    Inappropriate defense-alerting reaction to fear is a common feature of neuropsychiatric diseases. Therefore, impairments in brain circuits, as well as in molecular pathways underlying the neurovegetative adjustments to fear may play an essential role on developing neuropsychiatric disorders. Here we tested the hypothesis that interfering with angiotensin-(1-7) [Ang-(1-7)]/Mas receptor axis homeostasis, which appears to be essential to arterial pressure control, would affect fear memory and extinction. Mas knockout (MasKO) mice, in FVB/N background, showed normal cued fear memory and extinction, but increased freezing in response to context. Next, as FVB/N has poor performance in contextual fear memory, we tested MasKO in mixed 129xC57BL/6 background. MasKO mice behaved similarly to wild-type (WT), but memory extinction was slower in contextual fear conditioning to a weak protocol (1CS/US). In addition, delayed extinction in MasKO mice was even more pronounced after a stronger protocol (3CS/US). We showed previously that Angiotensin II receptor AT1 antagonist, losantan, rescued object recognition memory deficit in MasKO mice. Here, losartan was also effective. Memory extinction was accelerated in MasKO mice after treatment with losartan. In conclusion, we showed for the first time that Ang-(1-7)/Mas axis may modulate fear memory extinction. Furthermore, we suggest MasKO mice as an animal model to study post-traumatic stress disorder (PTSD). PMID:26642920

  1. Anode consumption on a subsea X-mas tree

    SciTech Connect

    Lye, R.E.

    1998-12-31

    Anode consumption and coating breakdown on a X-mas tree installed at the Troll Field in the Norwegian North Sea was investigated after 5 years. A comparison with a spare tree and one tree being exposed for only 3--4 months was done. The epoxy coating has several blisters, in particular on stainless steel surfaces. Water inside the blisters has a pH of 13-14 indicating that the cathodic reaction occurs inside them. The anode dimensions indicate an overall anode consumption of approximately 20%, while the design allows 27% after 5 years. This indicates that the original design is quite conservative. If the design had been done according to present day design rules, the conservatism would be reduced; an overall anode consumption of 23% is then likely (still less than allowed 27%).

  2. MODIS Airborne simulator (MAS) Final Report for CLASIC

    SciTech Connect

    Thomas Arnold; Steven Platnick

    2010-11-24

    The MAS was flown aboard the NASA ER-2 for the CLASIC field experiment, and for all data collected, provided calibrated and geolocated (Level-1B) radiance data for it’s 50 spectral bands (ranging in wavelength for 0.47 to 14.3 µm). From the Level-1B data, as directed in the Statement of Work, higher order (Level-2) data products were derived. The Level-2 products include: a) cloud optical thickness, b) cloud effective radius, c) cloud top height (temperature), d) cloud fraction, e) cloud phase products. Preliminary Level-1B and Level-2 products were provided during the field experiment (typically within one or two days of data collection). Final version data products were made available in December 2008 following considerable calibration analysis. Data collection, data processing (to Level-2), and discussion of the calibration work are summarized below.

  3. Food Waste Composting Study from Makanan Ringan Mas

    NASA Astrophysics Data System (ADS)

    Kadir, A. A.; Ismail, S. N. M.; Jamaludin, S. N.

    2016-07-01

    The poor management of municipal solid waste in Malaysia has worsened over the years especially on food waste. Food waste represents almost 60% of the total municipal solid waste disposed in the landfill. Composting is one of low cost alternative method to dispose the food waste. This study is conducted to compost the food waste generation in Makanan Ringan Mas, which is a medium scale industry in Parit Kuari Darat due to the lack knowledge and exposure of food waste recycling practice. The aim of this study is to identify the physical and chemical parameters of composting food waste from Makanan Ringan Mas. The physical parameters were tested for temperature and pH value and the chemical parameter are Nitrogen, Phosphorus and Potassium. In this study, backyard composting was conducted with 6 reactors. Tapioca peel was used as fermentation liquid and soil and coconut grated were used as the fermentation bed. Backyard composting was conducted with six reactors. The overall results from the study showed that the temperature of the reactors were within the range which are from 30° to 50°C. The result of this study revealed that all the reactors which contain processed food waste tend to produce pH value within the range of 5 to 6 which can be categorized as slightly acidic. Meanwhile, the reactors which contained raw food waste tend to produce pH value within the range of 7 to 8 which can be categorized as neutral. The highest NPK obtained is from Reactor B that process only raw food waste. The average value of Nitrogen is 48540 mg/L, Phosphorus is 410 mg/L and Potassium is 1550 mg/L. From the comparison with common chemical fertilizer, it shows that NPK value from the composting are much lower than NPK of the common chemical fertilizer. However, comparison with NPK of organic fertilizer shown only slightly difference value in NPK.

  4. Chemical shift referencing in MAS solid state NMR

    NASA Astrophysics Data System (ADS)

    Morcombe, Corey R.; Zilm, Kurt W.

    2003-06-01

    Solid state 13C magic angle spinning (MAS) NMR spectra are typically referenced externally using a probe which does not incorporate a field frequency lock. Solution NMR shifts on the other hand are more often determined with respect to an internal reference and using a deuterium based field frequency lock. Further differences arise in solution NMR of proteins and nucleic acids where both 13C and 1H shifts are referenced by recording the frequency of the 1H resonance of DSS (sodium salt of 2,2-dimethyl-2-silapentane-5-sulphonic acid) instead of TMS (tetramethylsilane). In this note we investigate the difficulties in relating shifts measured relative to TMS and DSS by these various approaches in solution and solids NMR, and calibrate adamantane as an external 13C standard for solids NMR. We find that external chemical shift referencing of magic angle spinning spectra is typically quite reproducible and accurate, with better than ±0.03 ppm accuracy being straight forward to achieve. Solid state and liquid phase NMR shifts obtained by magic angle spinning with external referencing agree with those measured using typical solution NMR hardware with the sample tube aligned with the applied field as long as magnetic susceptibility corrections and solvent shifts are taken into account. The DSS and TMS reference scales for 13C and 1H are related accurately using MAS NMR. Large solvent shifts for the 13C resonance in TMS in either deuterochloroform or methanol are observed, being +0.71 ppm and -0.74 ppm from external TMS, respectively. The ratio of the 13C resonance frequencies for the two carbons in solid adamantane to the 1H resonance of TMS is reported.

  5. Chemical shift referencing in MAS solid state NMR.

    PubMed

    Morcombe, Corey R; Zilm, Kurt W

    2003-06-01

    Solid state 13C magic angle spinning (MAS) NMR spectra are typically referenced externally using a probe which does not incorporate a field frequency lock. Solution NMR shifts on the other hand are more often determined with respect to an internal reference and using a deuterium based field frequency lock. Further differences arise in solution NMR of proteins and nucleic acids where both 13C and 1H shifts are referenced by recording the frequency of the 1H resonance of DSS (sodium salt of 2,2-dimethyl-2-silapentane-5-sulphonic acid) instead of TMS (tetramethylsilane). In this note we investigate the difficulties in relating shifts measured relative to TMS and DSS by these various approaches in solution and solids NMR, and calibrate adamantane as an external 13C standard for solids NMR. We find that external chemical shift referencing of magic angle spinning spectra is typically quite reproducible and accurate, with better than +/-0.03 ppm accuracy being straight forward to achieve. Solid state and liquid phase NMR shifts obtained by magic angle spinning with external referencing agree with those measured using typical solution NMR hardware with the sample tube aligned with the applied field as long as magnetic susceptibility corrections and solvent shifts are taken into account. The DSS and TMS reference scales for 13C and 1H are related accurately using MAS NMR. Large solvent shifts for the 13C resonance in TMS in either deuterochloroform or methanol are observed, being +0.71 ppm and -0.74 ppm from external TMS, respectively. The ratio of the 13C resonance frequencies for the two carbons in solid adamantane to the 1H resonance of TMS is reported. PMID:12810033

  6. Meridional Variations of C2H2 and C2H6 in Jupiter's Atmosphere from Cassini CIRS Infrared Spectra

    NASA Technical Reports Server (NTRS)

    Nixon, C. A.; Achterberg, R. K.; Conrath, B. J.; Irwin, P. G. J.; Fouchet, T.; Parrish, P. D.; Abbas, M.; LeClaire, A.; Romani, P. N.; Simon-Miller, A. A.

    2004-01-01

    The abundances of hydrocarbons such as acetylene (C2H2) and ethane (C2H6) in Jupiter's atmosphere are important physical quantities, constraining our models of the chemical and dynamical processes. However, our knowledge of these quantities and their vertical and latitudinal variations has remained sparse. The flyby of the Cassini spacecraft with Jupiter at the end of 2000 provided an excellent opportunity to observe the infrared spectrum with the Composite Infrared Spectrometer (CIRS) instrument, mapping the spatial variation of emissions from 10-1400 cm-1. CIRS spectra taken at the highest resolution (0.5 cm-1) in early December 2000 have been analysed to infer atmospheric temperatures in the stratosphere at 0.5-20 mbar via the v4 of CH4, and in the troposphere at 100-400 mbar, via the hydrogen collision-induced continuum absorption at 600-800 cm. Simultaneously, we have searched for meridional abundance variations in C2H2 and C2H6 via the v5 and vg bands respectively. Tropospheric absorption and stratospheric emission are highly anti-correlated at the CIM resolution, introducing a non-uniqueness into the retrievals, which means that vertical gradient and column abundance cannot be simultaneously found without additional constraints. If we assume the profile shapes from photochemical model calculations, we show that the column abundance of C2H2 must decrease sharply towards the poles, while C2H6 is constant or slightly increasing. The relevance of these results to current photochemical and dynamical knowledge of Jupiter's atmosphere is discussed.

  7. Evaluation of an electrochemical N2/H2 gas separator

    NASA Technical Reports Server (NTRS)

    Marshall, R. D.; Wynveen, R. A.; Carlson, J. N.

    1973-01-01

    A program was successfully completed to evaluate an electrochemical nitrogen/hydrogen (N2/H2) separator for use in a spacecraft nitrogen (N2) generator. Based on the technical data obtained a N2/H2 separator subsystem consisting of an organic polymer gas permeator first stage and an electrochemical second and third stage was estimated to have the lowest total spared equivalent weight, 257 kg (566 lb), for a 15 lb/day N2 generation rate. A pre-design analysis of the electrochemical N2/H2 separator revealed that its use as a first stage resulted in too high a power requirement to be competitive with the organic polymer membrane and the palladium-silver membrane separation methods. As a result, program emphasis was placed on evaluating the electrochemical. A parametric test program characterized cell performance and established second- and third-stage electrochemical N2/H2 separator operating conditions. A design verification test was completed on the second and third stages. The second stage was then successfully endurance tested for 200 hours.

  8. The distribution and abundance of interstellar C2H

    NASA Technical Reports Server (NTRS)

    Huggins, P. J.; Carlson, W. J.; Kinney, A. L.

    1984-01-01

    C2H(N = 1-0) emission has been extensively observed in a variety of molecular clouds, including: 12 hot, dense, cloud cores, 3 bright-rimmed clouds (in NGC 1977, IC 1396, and IC 1848), and across the extended OMC - 1 cloud. It has also been observed in the circumstellar envelopes IRC + 10216 and AFGL 2688. Abundance analyses of the molecular clouds yield C2H/(C-13)O abundance ratios of about 0.01, with little variation (less than about a factor of 4) either between clouds or across individual clouds. In the Orion plateau source, the C2H abundance is enhanced by less than a factor of 4, relative to the extended cloud. The generally high levels of C2H found in the molecular clouds are not readily accounted for by simple, steady-state chemical models, and suggest, as do earlier observations of atomic carbon, that the carbon chemistry in dense clouds is more active than is commonly assumed.

  9. Conformation-Specific Infrared Spectroscopy of γ2-PEPTIDE Foldamers: Ac-γ2-hPhe-γ2-hAla-NHMe and Ac-γ2-hAla-γ2-hPhe-NHMe

    NASA Astrophysics Data System (ADS)

    James, William H., III; Buchanan, Evan G.; Müller, Christian W.; Zwier, Timothy S.; Guo, Li; Gellman, Samuel H.

    2010-06-01

    IR/UV double-resonance spectroscopy has been used to study the intrinsic conformational preferences of naturally occurring and synthetic peptides. These studies demonstrated the power of double-resonance methods and highlighted the ability of even short peptide mimics to form a variety of intramolecular hydrogen bonded architectures. Currently, we are extending these studies to a series of model γ2-peptides, which differ from α-peptides by virtue of having two additional, substitutable methylene units separating amide groups in the peptide backbone. Initial studies centered on the conformation-specific infrared spectra of Ac-γ2-hPhe-NHMe, where three unique conformational isomers (two hydrogen-bonded and one intramolecular amide stacked) were observed under the isolated-molecule conditions of a jet-cooled environment. This talk will focus on on two larger γ2-peptides, Ac-γ2-hPhe-γ2-hAla-NHMe and Ac-γ2-hAla-γ2-hPhe-NHMe. Utilizing resonant ion-dip infrared spectroscopy, the single-conformation infrared spectra of eight resolved conformers of the two molecules were recorded in the amide NH stretch region. The resulting infrared spectra of the tri-amides contain evidence for structures comprised of one, two, and three intramolecular amide-amide hydrogen bonds, the last of which is unprecedented for a tri-amide. In an effort to make firm conformational assignments, the spectroscopic data will be compared to the results of harmonic vibrational frequency calculations using traditional DFT and dispersion-corrected DFT methods, the results of which will be discussed.

  10. Search for the isomers of C2H3NO and C2H3NS in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Etim, Emmanuel; Chakrabarti, Sandip Kumar; Das, Ankan; Gorai, Prasanta; Arunan, Elangannan

    2016-07-01

    With about 40% of all the known interstellar and circumstellar molecules having their isomeric analogues as known astromolecules, isomerism remains one of the leading themes in interstellar chemistry. In this regard, the recent detection of methyl isocyanate (with a number of isomeric analogues) in the Sgr B2(N) giant molecular cloud opens a new window for the possible astronomical detection of other C_2H_3NO isomers. The present work looks at the possibility of detecting other isomers of methyl isocyanate by considering different factors such as thermodynamic stability of the different isomers with respect to the Energy, Stability and Abundance (ESA) relationship, effect of interstellar hydrogen bonding with respect to the formation these isomers on the surface of the interstellar dust grains, possible formation routes for these isomers, spectroscopic parameters for potential astromolecules among these isomers, chemical modeling among other studies. The same studies are repeated for the C_2H_3NS isomers which are the isoelectroninc analogues of the C_2H_3NO isomers taking into account the unique chemistry of S and O-containing interstellar molecular species. Among the C_2H_3NS isomers, methyl isothiocyanate remains the most potential candidate for astronomical observation.

  11. The infrared spectra of C2H4(+) and C2H3 trapped in solid neon.

    PubMed

    Jacox, Marilyn E; Thompson, Warren E

    2011-02-14

    When a mixture of ethylene in a large excess of neon is codeposited at 4.3 K with a beam of neon atoms that have been excited in a microwave discharge, two groups of product absorptions appear in the infrared spectrum of the deposit. Similar studies using C(2)H(4)-1-(13)C and C(2)D(4) aid in product identification. The first group of absorptions arises from a cation product which possesses two identical carbon atoms, giving the first infrared identification of two fundamentals of C(2)H(4)(+) and three of C(2)D(4)(+), as well as a tentative identification of ν(9) of C(2)H(4)(+). The positions of these absorptions are consistent with the results of density functional calculations and of earlier photoelectron studies. All of the members of the second group of product absorptions possess two inequivalent carbon atoms. They are assigned to the vinyl radical, C(2)H(3), and to C(2)D(3), in agreement with other recent infrared assignments for those species. PMID:21322694

  12. Observations of CH4, C2H6, and C2H2 in the stratosphere of Jupiter.

    PubMed

    Sada, P V; Bjoraker, G L; Jennings, D E; McCabe, G H; Romani, P N

    1998-12-01

    We have performed high-resolution spectral observations at mid-infrared wavelengths of CH4 (8.14 micrometers), C2H6 (12.16 micrometers), and C2H2 (13.45 micrometers) on Jupiter. These emission features probe the stratosphere of the planet and provide information on the carbon-based photochemical processes taking place in that region of the atmosphere. The observations were performed using our cryogenic echelle spectrometer CELESTE, in conjunction with the McMath-Pierce 1.5-m solar telescope between November 1994 and February 1995. We used the methane observations to derive the temperature profile of the jovian atmosphere in the 1-10 mbar region of the stratosphere. This profile was then used in conjunction with height-dependent mixing ratios of each hydrocarbon to determine global abundances for ethane and acetylene. The resulting mixing ratios are 3.9(+1.9)(-1.3) x 10(-6) for C2H6 (5 mbar pressure level), and 2.3 +/- 0.5 x 10(-8) for C2H2 (8 mbar pressure level), where the quoted uncertainties are derived from model variations in the temperature profile which match the methane observation uncertainties. PMID:11878354

  13. A new NMR method for determining the particle thickness in nanocomposites, using T2,H-selective X{1H} recoupling.

    PubMed

    Schmidt-Rohr, K; Rawal, A; Fang, X-W

    2007-02-01

    A new nuclear magnetic resonance approach for characterizing the thickness of phosphate, silicate, carbonate, and other nanoparticles in organic-inorganic nanocomposites is presented. The particle thickness is probed using the strongly distant-dependent dipolar couplings between the abundant protons in the organic phase and X nuclei (31P, 29Si, 13C, 27Al, 23Na, etc.) in the inorganic phase. This approach requires pulse sequences with heteronuclear dephasing only by the polymer or surface protons that experience strong homonuclear interactions, but not by dispersed OH or water protons in the inorganic phase, which have long transverse relaxation times T2,H. This goal is achieved by heteronuclear recoupling with dephasing by strong homonuclear interactions of protons (HARDSHIP). The pulse sequence alternates heteronuclear recoupling for approximately 0.15 ms with periods of homonuclear dipolar dephasing that are flanked by canceling 90 degrees pulses. The heteronuclear evolution of the long-T2,H protons is refocused within two recoupling periods, so that 1H spin diffusion cannot significantly dephase these coherences. For the short-T2,H protons of a relatively immobile organic matrix, the heteronuclear dephasing rate depends simply on the heteronuclear second moment. Homonuclear interactions do not affect the dephasing, even though no homonuclear decoupling is applied, because long-range 1H-X dipolar couplings approximately commute with short-range 1H-1H couplings, and heteronuclear recoupling periods are relatively short. This is shown in a detailed analysis based on interaction representations. The algorithm for simulating the dephasing data is described. The new method is demonstrated on a clay-polymer nanocomposite, diamond nanocrystals with protonated surfaces, and the bioapatite-collagen nanocomposite in bone, as well as pure clay and hydroxyapatite. The diameters of the nanoparticles in these materials range between 1 and 5 nm. Simulations show that spherical

  14. Inverse Kinematic Study of the (26g)Al(d,p)(27)Al Reaction and Implications for Destruction of (26)Al in Wolf-Rayet and Asymptotic Giant Branch Stars.

    PubMed

    Margerin, V; Lotay, G; Woods, P J; Aliotta, M; Christian, G; Davids, B; Davinson, T; Doherty, D T; Fallis, J; Howell, D; Kirsebom, O S; Mountford, D J; Rojas, A; Ruiz, C; Tostevin, J A

    2015-08-01

    In Wolf-Rayet and asymptotic giant branch (AGB) stars, the (26g)Al(p,γ)(27)Si reaction is expected to govern the destruction of the cosmic γ-ray emitting nucleus (26)Al. The rate of this reaction, however, is highly uncertain due to the unknown properties of key resonances in the temperature regime of hydrogen burning. We present a high-resolution inverse kinematic study of the (26g)Al(d,p)(27)Al reaction as a method for constraining the strengths of key astrophysical resonances in the (26g)Al(p,γ)(27)Si reaction. In particular, the results indicate that the resonance at E(r)=127  keV in (27)Si determines the entire (26g)Al(p,γ)(27)Si reaction rate over almost the complete temperature range of Wolf-Rayet stars and AGB stars. PMID:26296114

  15. Absolute shielding scales for Al, Ga, and In and revised nuclear magnetic dipole moments of {sup 27}Al, {sup 69}Ga, {sup 71}Ga, {sup 113}In, and {sup 115}In nuclei

    SciTech Connect

    Antušek, A. Holka, F.

    2015-08-21

    We present coupled cluster calculations of NMR shielding constants of aluminum, gallium, and indium in water-ion clusters. In addition, relativistic and dynamical corrections and the influence of the second solvation shell are evaluated. The final NMR shielding constants define new absolute shielding scales, 600.0 ± 4.1 ppm, 2044.4 ± 31.4 ppm, and 4507.7 ± 63.7 ppm for aluminum, gallium, and indium, respectively. The nuclear magnetic dipole moments for {sup 27}Al, {sup 69}Ga, {sup 71}Ga, {sup 113}In, and {sup 115}In isotopes are corrected by combining the computed shielding constants with experimental NMR frequencies. The absolute magnitude of the correction increases along the series and for indium isotopes it reaches approximately −8.0 × 10{sup −3} of the nuclear magneton.

  16. 27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy of glasses in the system K2O-Al2O3-SiO2.

    PubMed

    Mundus, C; Müller-Warmuth, W

    1995-10-01

    27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy at 78 MHz has been applied to determine (true) chemical shift and quadrupole coupling parameters of glasses in the system K2O-Al2O3-SiO2 with 60-80 mol% SiO2 and K2O concentrations between 0 and 24 mol%. The powdered crystalline aluminosilicates andalusite and sillimanite have also been examined. In the glasses, all Al appears to be tetrahedrally bound in the aluminosilicate network unless x = mol% K2O:mol% Al2O3 becomes extremely small. Upon decreasing x the distortion of the tetrahedral Al(OSi)4 units increases in steps, and possible explanations are discussed. Six-coordinated aluminum observed for x < 0.2 is connected with the occurrence of interstitial Al3+ ions which charge-compensate the AlO4 units in addition to K+. PMID:8748646

  17. Mas-Mediated Antioxidant Effects Restore the Functionality of Angiotensin Converting Enzyme 2-Angiotensin-(1–7)-Mas Axis in Diabetic Rat Carotid

    PubMed Central

    Gomes, Mayara Santos; Restini, Carolina Baraldi Araujo

    2014-01-01

    We hypothesized that endothelial AT1-activated NAD(P)H oxidase-driven generation of reactive oxygen species during type I-diabetes impairs carotid ACE2-angiotensin-(1–7)-Mas axis functionality, which accounts for the impaired carotid flow in diabetic rats. We also hypothesized that angiotensin-(1–7) chronic treatment of diabetic rats restores carotid ACE2-angiotensin-(1–7)-Mas axis functionality and carotid flow. Relaxant curves for angiotensin II or angiotensin-(1–7) were obtained in carotid from streptozotocin-induced diabetic rats. Superoxide or hydrogen peroxide levels were measured by flow cytometry in carotid endothelial cells. Carotid flow was also determined. We found that endothelial AT1-activated NAD(P)H oxidase-driven generation of superoxide and hydrogen peroxide in diabetic rat carotid impairs ACE2-angiotensin-(1–7)-Mas axis functionality, which reduces carotid flow. In this mechanism, hydrogen peroxide derived from superoxide dismutation inhibits ACE2 activity in generating angiotensin-(1–7) seemingly by activating ICl,SWELL, while superoxide inhibits the nitrergic Mas-mediated vasorelaxation evoked by angiotensin-(1–7). Angiotensin-(1–7) treatment of diabetic rats restored carotid ACE2-angiotensin-(1–7)-Mas axis functionality by triggering a positive feedback played by endothelial Mas receptors, that blunts endothelial AT1-activated NAD(P)H oxidase-driven generation of reactive oxygen species. Mas-mediated antioxidant effects also restored diabetic rat carotid flow, pointing to the contribution of ACE2-angiotensin-(1–7)-Mas axis in maintaining carotid flow. PMID:24877125

  18. Defects and hyperfine interactions in Ni Y intermetallics (Y = Al, Ga, In, Ti) via 27Al, 47Ti, 61Ni, 69,71Ga and 115In nuclear resonance

    NASA Astrophysics Data System (ADS)

    Bastow, T. J.; West, G. W.

    2003-12-01

    Defect structures and nuclear electric hyperfine interactions have been investigated in a series of binary Ni-Al, Ni-Ga, Ni-In intermetallic compounds, and the shape memory compound NiTi using 27Al, 47,49Ti, 61Ni, 71Ga and 115In nuclear resonance. Components of the 61Ni NMR spectrum for a series of cubic Ni1-xAlx and Ni1-xGax specimens on either side of x = 0.5 have been identified as due to Ni substitutions and Al (or Ga) vacancies. For stoichiometric NiAl, Ni2Al3 and NiAl3 the 61Ni lines are narrow and distinguished by well-separated Knight shifts, although the 61Ni lineshape for the ordered vacancy compound Ni3Al4 indicates a substantial nuclear quadrupole interaction at the Ni site. The substitution for Al of the group III elements Ga and In, which have isoelectronic outer shells, acts to increase the 61Ni Knight shift such that 61K(Al)<61K(Ga)<61K(In). This trend is observed not only for cubic NiAl and NiGa, but also for trigonal Ni2Al3, Ni2Ga3 and Ni2In3. In NiTi the sharp first-order transition between the (high-temperature) cubic phase and the (low-temperature) monoclinic phase has been observed while monitoring the 61Ni and 49,47Ti NMR lineshapes as a function of temperature. In the non-cubic phases of these materials (including hexagonal egr-NiIn) the electric field gradient tensor components Vzz and eegr at the atomic sites have been determined from the nuclear quadrupole perturbed 27Al, 47Ti, 61Ni, 71Ga NMR lineshapes together with 69Ga and 115In NQR transition frequencies, and compared with values derived from ab initio calculation.

  19. Be(3)(AsO4)2. 2H2O, a new berylloarsenate phase containing bridged tetrahedral 3-rings. Technical report, 1 June 1992-31 May 1993

    SciTech Connect

    Harrison, W.T.; Nenoff, T.M.; Gier, T.E.; Stucky, G.D.

    1993-02-15

    The high-temperature/high-pressure hydrothermal synthesis and X-ray single crystal structure of Be3(AsO4)2(dot)2H2O is described: the title compound contains a three-dimensional network of BeO4 and AsO4 tetrahedra. The structural motif includes infinite layers of bridged tetrahedral 3- and 4-rings. 9Be MAS NMR data are consistent with the Be-atom environments in the crystal structure.

  20. Refractive index and birefringence of 2H silicon carbide

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1972-01-01

    The refractive indices of 2H SiC were measured over the wavelength range 435.8 to 650.9 nm by the method of minimum deviation. At the wavelength lambda = 546.1 nm, the ordinary index n sub 0 was 2.6480 and the extraordinary index n sub e was 2.7237. The estimated error (standard deviation) in the measured values is 0.0006 for n sub 0 and 0.0009 for n sub e. The experimental data were curve fitted to the Cauchy equation for the index of refraction as a function of wavelength. The birefringence of 2H SiC was found to vary from 0.0719 at lambda = 650.9 nm to 0.0846 at lambda = 435.8 nm.

  1. Lattice Instability of 2H-TaSe2

    NASA Astrophysics Data System (ADS)

    John Bosco Balaguru, R.; Lawrence, N.; Alfred Cecil Raj, S.

    The charge density wave (CDW) in the layered compound 2H-TaSe2 at low temperatures has a commensurate phase, which causes super lattice points to appear in the Brillöuin zone of the undistorted phase. A Born-von Karman formalism has been employed for the calculation of phonon frequency distribution curves of 2H-TaSe2 both in the normal and in the commensurate charge density wave (CCDW) phases. A folding technique has been adopted for the calculation in the CCDW phase. The phonon distribution for both the phases have been reported. With these distributions the thermal properties such as specific heat capacity, Debye Waller factor W(k) and thermal conductivity have been worked out, and compared with the available experimental results.

  2. C(2)H(4) metabolism in morning glory flowers.

    PubMed

    Beyer, E M; Sundin, O

    1978-06-01

    Flowers of Ipomoea tricolor Cav. (cv. Heavenly Blue) were cut at various stages of development and evaluated for their ability to metabolize ethylene. Freshly cut buds or flowers were treated in glass containers for 8 hours with 6 mul/liter of highly purified (14)C(2)H(4). Following removal of dissolved (14)C(2)H(4), radioactivity was determined for the different flower tissues and trappd CO(2). (14)C(2)H(4) oxidation to (14)CO(2) and tissue incorporation occurred at very low to nondetectable levels 2 to 3 days prior to flower opening. About 1 day prior to full bloom, just at the time when mature buds become responsive to ethylene (Kende and Hanson, Plant Physiol 1976, 57: 523-527), there was a dramatic increase in the capacity of the buds to oxidize (14)C(2)H(4) to (14)CO(2). This activity continued to increase until the flower was fully opened reaching a peak activity of 2,500 dpm per three flowers per 8 hours. It then declined as the flower closed and rapidly senesced. A similar but smaller peak occurred in tissue incorporation and it was followed by a second peak during late flower senescence. This first peak in tissue incorporation and the dramatic peak in ethylene oxidation slightly preceded a large peak of natural ethylene production which accompanied flower senescence. The ethylene metabolism observed was clearly dependent on cellular metabolism and did not involve microorganisms since heat killing destroyed this activity and badly contaminated heat-killed flowers were unable to metabolize ethylene. PMID:16660421

  3. Charge transfer in energetic Li^2+ - H collisions

    NASA Astrophysics Data System (ADS)

    Mancev, I.

    2008-07-01

    The total cross sections for charge transfer in Li^2+ - H collisions have been calculated, using the four-body first Born approximation with correct boundary conditions (CB1-4B) and four-body continuum distorted wave method (CDW-4B) in the energy range 10 - 5000 keV/amu. Present results call for additional experimental data at higher impact energies than presently available.

  4. 2H Evaporator CP class instrumentation uncertainties evaluations

    SciTech Connect

    Hwang, E.

    1994-02-10

    The Evaporator Pot Temperature Instrumentations and the Steam Condensate Gamma Monitors are two instrumentation systems in the 2H Evaporator facilities that are classified as the critical protection. The temperature high alarm and interlock circuit and the temperature recorder circuit of the pot temperature instrumentation loop are described. From the gamma monitor loop, the high gamma alarm and interlock circuit, failure alarm and interlock circuit, cesium activity recorder circuit, and americium activity recorder circuit are described. (GHH)

  5. Decentralized method for complex task allocation in massive MAS

    NASA Astrophysics Data System (ADS)

    Brahmi, Zaki; Gammoudi, M. M.

    2008-06-01

    Task allocation is still a fundamental problem in Multi-Agents System (MAS). It allows the formation a coalition of agents to cooperate together in order to carry out a complex task. Generally, the process of task allocation requires calculating the value of all the possible allocations, then determining which optimal. In the context of Massive Multi-Agent Systems (MMAS), one agent generates all the possible coalitions and then calculates the value of each, is inefficient. Moreover, the traditional approaches based on the negotiation between agents, are impractical because of the complexity of communications between agents. In this paper we propose a decentralized method, based on grouping agents using the Formal Concepts Analysis (FCA) approach for the task allocation in MMAS. In our model, agents are fully cooperative and each task is composed of several subtasks. The proposed solution is based on two steps: i) computing groups of agents having similar characteristics in the objective to distribute the task allocation process among agents and minimize the communication between agents. ii) Finding the optimal allocation by sharing the task allocation process among groups of agents.

  6. Distributed Cooperation Solution Method of Complex System Based on MAS

    NASA Astrophysics Data System (ADS)

    Weijin, Jiang; Yuhui, Xu

    To adapt the model in reconfiguring fault diagnosing to dynamic environment and the needs of solving the tasks of complex system fully, the paper introduced multi-Agent and related technology to the complicated fault diagnosis, an integrated intelligent control system is studied in this paper. Based on the thought of the structure of diagnostic decision and hierarchy in modeling, based on multi-layer decomposition strategy of diagnosis task, a multi-agent synchronous diagnosis federation integrated different knowledge expression modes and inference mechanisms are presented, the functions of management agent, diagnosis agent and decision agent are analyzed, the organization and evolution of agents in the system are proposed, and the corresponding conflict resolution algorithm in given, Layered structure of abstract agent with public attributes is build. System architecture is realized based on MAS distributed layered blackboard. The real world application shows that the proposed control structure successfully solves the fault diagnose problem of the complex plant, and the special advantage in the distributed domain.

  7. Measurement of regional cerebral blood flow in cat brain using intracarotid 2H2O and 2H NMR imaging

    SciTech Connect

    Detre, J.A.; Subramanian, V.H.; Mitchell, M.D.; Smith, D.S.; Kobayashi, A.; Zaman, A.; Leigh, J.S. Jr. )

    1990-05-01

    Cerebral blood flow (CBF) was measured in cat brain in vivo at 2.7 T using 2H NMR to monitor the washout of deuterated saline injected into both carotid arteries via the lingual arteries. In anesthetized cats, global CBF varied directly with PaCO{sub 2} over a range of 20-50 mm Hg, and the corresponding global CBF values ranged from 25 to 125 ml.100 g-1.min-1. Regional CBF was measured in a 1-cm axial section of cat brain using intracarotid deuterated saline and gradient-echo 2H NMR imaging. Blood flow images with a maximum pixel resolution of 0.3 x 0.3 x 1.0 cm were generated from the deuterium signal washout at each pixel. Image derived values for CBF agreed well with other determinations, and decreased significantly with hypocapnia.

  8. Psychometric Comparison of the Motivation Assessment Scale (MAS) and the Questions about Behavioral Function (QABF)

    ERIC Educational Resources Information Center

    Koritsas, S.; Iacono, T.

    2013-01-01

    Background: The Motivation Assessment Scale (MAS) and the Questions About Behavioral Function (QABF) are frequently used to assess the learned function of challenging behaviour in people with intellectual disability (ID). The aim was to explore and compare the psychometric properties of the MAS and the QABF. Method: Seventy adults with ID and…

  9. MAS-NMR studies of lithium aluminum silicate (LAS) glasses and glass-ceramics having different Li{sub 2}O/Al{sub 2}O{sub 3} ratio

    SciTech Connect

    Ananthanarayanan, A.; Kothiyal, G.P.; Montagne, L.; Revel, B.

    2010-01-15

    Emergence of phases in lithium aluminum silicate (LAS) glasses of composition (wt%) xLi{sub 2}O-71.7SiO{sub 2}-(17.7-x)Al{sub 2}O{sub 3}-4.9K{sub 2}O-3.2B{sub 2}O{sub 3}-2.5P{sub 2}O{sub 5} (5.1<=x<=12.6) upon heat treatment were studied. {sup 29}Si, {sup 27}Al, {sup 31}P and {sup 11}B MAS-NMR were employed for structural characterization of both LAS glasses and glass-ceramics. In glass samples, Al is found in tetrahedral coordination, while P exists mainly in the form of orthophosphate units. B exists as BO{sub 3} and BO{sub 4} units. {sup 27}Al NMR spectra show no change with crystallization, ruling out the presence of any Al containing phase. Contrary to X-ray diffraction studies carried out, {sup 11}B (high field 18.8 T) and {sup 29}Si NMR spectra clearly indicate the unexpected crystallization of a borosilicate phase (Li,K)BSi{sub 2}O{sub 6}, whose structure is similar to the aluminosilicate virgilite. Also, lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}), lithium metasilicate (Li{sub 2}SiO{sub 3}) and quartz (SiO{sub 2}) were identified in the {sup 29}Si NMR spectra of the glass-ceramics. {sup 31}P NMR spectra of the glass-ceramics revealed the presence of Li{sub 3}PO{sub 4} and a mixed phase (Li,K){sub 3}PO{sub 4} at low alkali concentrations. - Graphical Abstract: The {sup 11}B MAS-NMR spectra of lithium aluminum silicate (LAS) glass-ceramics indicating the formation of Li/KBSiO{sub 6} phase. This phase is isostructural with virgilite and cannot be distinguished in X-ray diffractograms.

  10. CO2/H(+) sensing: peripheral and central chemoreception.

    PubMed

    Lahiri, Sukhamay; Forster, Robert E

    2003-10-01

    H(+) is maintained constant in the internal environment at a given body temperature independent of external environment according to Bernard's principle of "milieu interieur". But CO2 relates to ventilation and H(+) to kidney. Hence, the title of the chapter. In order to do this, sensors for H(+) in the internal environment are needed. The sensor-receptor is CO2/H(+) sensing. The sensor-receptor is coupled to integrate and to maintain the body's chemical environment at equilibrium. This chapter dwells on this theme of constancy of H(+) of the blood and of the other internal environments. [H(+)] is regulated jointly by respiratory and renal systems. The respiratory response to [H(+)] originates from the activities of two groups of chemoreceptors in two separate body fluid compartments: (A) carotid and aortic bodies which sense arterial P(O2) and H(+); and (B) the medullary H(+) receptors on the ventrolateral medulla of the central nervous system (CNS). The arterial chemoreceptors function to maintain arterial P(O2) and H(+) constant, and medullary H(+) receptors to maintain H(+) of the brain fluid constant. Any acute change of H(+) in these compartments is taken care of almost instantly by pulmonary ventilation, and slowly by the kidney. This general theme is considered in Section 1. The general principles involving cellular CO2 reactions mediated by carbonic anhydrase (CA), transport of CO2 and H(+) are described in Section 2. Since the rest of the chapter is dependent on these key mechanisms, they are given in detail, including the role of Jacobs-Stewart Cycle and its interaction with carbonic anhydrase. Also, this section deals briefly with the mechanisms of membrane depolarization of the chemoreceptor cells because this is one mechanism on which the responses depend. The metabolic impact of endogenous CO2 appears in the section with a historical twist, in the context of acclimatization to high altitude (Section 3). Because low P(O2) at high altitude stimulates

  11. A generic, computerized nuclear materials accountability system (NucMAS) and its layered products

    SciTech Connect

    Davis, Jr, J M

    1989-01-01

    NucMAS provides a material balance area with a computerized data management system for nuclear materials accountability. NucMAS is a generic application. It handles the data management and reporting functions for different processing facilities by storing all process-specific information as data rather than procedure. A NucMAS application is configured for each facility it supports. NucMAS and its layered products are compatible with three types of data clients. Core NucMAS has a screen-oriented user interface to support the accountability clerk as a client. Accountability clerks enter data from operating logs and laboratory analyses one to three days after actual processing. Layered products support process operators and automated systems as near-real-time and real-time data clients. The core and layered products use a data-driven approach which results in software that is configurable and maintainable. 3 refs., 5 figs.

  12. Theoretical kinetics of O + C2H4

    DOE PAGESBeta

    Li, Xiaohu; Jasper, Ahren W.; Zádor, Judit; Miller, James A.; Klippenstein, Stephen J.

    2016-06-01

    The reaction of atomic oxygen with ethylene is a fundamental oxidation step in combustion and is prototypical of reactions in which oxygen adds to double bonds. For 3O+C2H4 and for this class of reactions generally, decomposition of the initial adduct via spin-allowed reaction channels on the triplet surface competes with intersystem crossing (ISC) and a set of spin-forbidden reaction channels on the ground-state singlet surface. The two surfaces share some bimolecular products but feature different intermediates, pathways, and transition states. In addition, the overall product branching is therefore a sensitive function of the ISC rate. The 3O+C2H4 reaction has beenmore » extensively studied, but previous experimental work has not provided detailed branching information at elevated temperatures, while previous theoretical studies have employed empirical treatments of ISC. Here we predict the kinetics of 3O+C2H4 using an ab initio transition state theory based master equation (AITSTME) approach that includes an a priori description of ISC. Specifically, the ISC rate is calculated using Landau–Zener statistical theory, consideration of the four lowest-energy electronic states, and a direct classical trajectory study of the product branching immediately after ISC. The present theoretical results are largely in good agreement with existing low-temperature experimental kinetics and molecular beam studies. Good agreement is also found with past theoretical work, with the notable exception of the predicted product branching at elevated temperatures. Above ~1000 K, we predict CH2CHO+H and CH2+CH2O as the major products, which differs from the room temperature preference for CH3+HCO (which is assumed to remain at higher temperatures in some models) and from the prediction of a previous detailed master equation study.« less

  13. Rotational spectroscopy of 2H,3H-perfluoropentane

    NASA Astrophysics Data System (ADS)

    Duong, Chinh H.; Obenchain, Daniel A.; Cooke, S. A.; Novick, Stewart E.

    2016-06-01

    The structure of 2H,3H-perfluoropentane, CF3CHFCHFCF2CF3, has been determine by a combination of Chirp-pulsed Fourier transform microwave (CP-FTMW) spectroscopy and cavity FTMW spectroscopy. Of the four possible stereoisomers, only the enantiomeric pair (R,R)/(S,S) were observed experimentally; there was no spectroscopic evidence for the enantiomeric pair (R,S)/(S,R). The conformeric structure of the (R,R)/(S,S) stereoisomer(s) was that of partial helices with C-C-C-C dihedral angles of 12° (helical) and 1° (staggered).

  14. Synthesis Of 2h- And 13c-Substituted Dithanes

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2004-05-04

    The present invention is directed to labeled compounds, [2-.sup.13 C]dithane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to processes of preparing [2-.sup.13 C]dithane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to labeled compounds, e.g., [.sup.2 H.sub.1-2, .sup.13 C]methanol (arylthio)-, acetates wherein the .sup.13 C atom is directly bonded to exactly one or two deuterium atoms.

  15. Synthesis of 2H- and 13C-substituted dithanes

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2003-01-01

    The present invention is directed to labeled compounds, [2-.sup.13 C]dithiane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to processes of preparing [2-.sup.13 C]dithiane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to labeled compounds, e.g., [.sup.2 H.sub.1-2, .sup.13 C]methanol (arylthio)-, acetates wherein the .sup.13 C atom is directly bonded to exactly one or two deuterium atoms.

  16. Dissociative attachment of electrons with Si2H6

    NASA Technical Reports Server (NTRS)

    Krishnakumar, E.; Srivastava, S. K.; Iga, I.

    1991-01-01

    Cross-sections for the production of negative ion fragments by electron attachment to Si2H6 and ion pair formation from it have been measured by utilizing the crossed electron beam-molecular beam collision technique. The negative ions are mass-analyzed by employing a quadrupole mass spectrometer. There are serious disagreements between the present and two previously published results. In the present paper cross-section values, appearance potentials, and the various channels of dissociation for the formation of negative monosilane fragments are presented.

  17. A microporous six-fold interpenetrated hydrogen-bonded organic framework for highly selective separation of C2H4/C2H6.

    PubMed

    Li, Peng; He, Yabing; Arman, Hadi D; Krishna, Rajamani; Wang, Hailong; Weng, Linhong; Chen, Banglin

    2014-11-01

    A unique six-fold interpenetrated hydrogen-bonded organic framework (HOF) has been developed, for the first time, for highly selective separation of C2H4/C2H6 at room temperature and normal pressure. PMID:25223376

  18. Atypical Signaling and Functional Desensitization Response of MAS Receptor to Peptide Ligands

    PubMed Central

    Tirupula, Kalyan C.; Desnoyer, Russell; Speth, Robert C.; Karnik, Sadashiva S.

    2014-01-01

    MAS is a G protein-coupled receptor (GPCR) implicated in multiple physiological processes. Several physiological peptide ligands such as angiotensin-(1–7), angiotensin fragments and neuropeptide FF (NPFF) are reported to act on MAS. Studies of conventional G protein signaling and receptor desensitization upon stimulation of MAS with the peptide ligands are limited so far. Therefore, we systematically analyzed G protein signals activated by the peptide ligands. MAS-selective non-peptide ligands that were previously shown to activate G proteins were used as controls for comparison on a common cell based assay platform. Activation of MAS by the non-peptide agonist (1) increased intracellular calcium and D-myo-inositol-1-phosphate (IP1) levels which are indicative of the activation of classical Gαq-phospholipase C signaling pathways, (2) decreased Gαi mediated cAMP levels and (3) stimulated Gα12-dependent expression of luciferase reporter. In all these assays, MAS exhibited strong constitutive activity that was inhibited by the non-peptide inverse agonist. Further, in the calcium response assay, MAS was resistant to stimulation by a second dose of the non-peptide agonist after the first activation has waned suggesting functional desensitization. In contrast, activation of MAS by the peptide ligand NPFF initiated a rapid rise in intracellular calcium with very weak IP1 accumulation which is unlike classical Gαq-phospholipase C signaling pathway. NPFF only weakly stimulated MAS-mediated activation of Gα12 and Gαi signaling pathways. Furthermore, unlike non-peptide agonist-activated MAS, NPFF-activated MAS could be readily re-stimulated the second time by the agonists. Functional assays with key ligand binding MAS mutants suggest that NPFF and non-peptide ligands bind to overlapping regions. Angiotensin-(1–7) and other angiotensin fragments weakly potentiated an NPFF-like calcium response at non-physiological concentrations (≥100 µM). Overall, our data

  19. B2H6 PLAD Doped PMOS Device Performance

    SciTech Connect

    Fang, Z.; Miller, T.; Winder, E.; Persing, H.; Arevalo, E.; Gupta, A.; Parrill, T.; Singh, V.; Qin, S.; McTeer, A.

    2006-11-13

    Plasma doping (PLAD) achieves high wafer throughput by directly extracting ions across the plasma sheath. PLAD profiles are typically surface peaked instead of retrograde as obtained from beamline (BL) implant. It may require optimization of PLAD energy and dose in order to match BL doping results. From device optimization point of view, it is necessary to understand the impact of doping parameters to device characteristics. In this paper we present the PMOS device performance with the poly gate and source drain (SD) implants carried out using B2H6 PLAD. The BL control conditions are 2-5 keV 11B+ 4-6x1015 cm-2. Equivalent device performance for p+ poly gate doping is obtained using PLAD with B2H6 / H2. In SD doping using same gas mixture, nearly 50% reduction in SD contact resistance is observed in the PLAD splits. The reduction in SD contact resistance leads to 10-15% increase in device on-current, hence demonstrating the process advantages of using PLAD in addition to having a high wafer throughput.

  20. MasABK Proteins Interact with Proteins of the Type IV Pilin System to Affect Social Motility of Myxococcus xanthus

    PubMed Central

    Fremgen, Sarah; Williams, Amanda; Furusawa, Gou; Dziewanowska, Katarzyna; Settles, Matthew; Hartzell, Patricia

    2013-01-01

    Gliding motility is critical for normal development of spore-filled fruiting bodies in the soil bacterium Myxococcus xanthus. Mutations in mgl block motility and development but one mgl allele can be suppressed by a mutation in masK, the last gene in an operon adjacent to the mgl operon. Deletion of the entire 5.5 kb masABK operon crippled gliding and fruiting body development and decreased sporulation. Expression of pilAGHI, which encodes type IV pili (TFP) components essential for social (S) gliding, several cryptic pil genes, and a LuxR family protein were reduced significantly in the Δmas mutant while expression of the myxalamide operon was increased significantly. Localization and two-hybrid analysis suggest that the three Mas proteins form a membrane complex. MasA-PhoA fusions confirmed that MasA is an integral cytoplasmic membrane protein with a ≈100 amino acid periplasmic domain. Results from yeast two-hybrid assays showed that MasA interacts with the lipoprotein MasB and MasK, a protein kinase and that MasB and MasK interact with one another. Additionally, yeast two-hybrid analysis revealed a physical interaction between two gene products of the mas operon, MasA and MasB, and PilA. Deletion of mas may be accompanied by compensatory mutations since complementation of the Δmas social gliding and developmental defects required addition of both pilA and masABK. PMID:23342171

  1. Sealed rotors for in situ high temperature high pressure MAS NMR

    DOE PAGESBeta

    Hu, Jian Z.; Hu, Mary Y.; Zhao, Zhenchao; Xu, Souchang; Vjunov, Aleksei; Shi, Hui; Camaioni, Donald M.; Peden, Charles H. F.; Lercher, Johannes A.

    2015-07-06

    Magic angle spinning (MAS) nuclear magnetic resonance (NMR) investigations on heterogeneous samples containing solids, semi-solids, liquid and gases or a mixture of them under non-conventional conditions of a combined high pressure and high temperature, or cold temperature suffer from the unavailability of a perfectly sealed rotor. Here, we report the design of reusable and perfectly-sealed all-zircornia MAS rotors. The rotors are easy to use and are suitable for operation temperatures from below 0 to 250 °C and pressures up to 100 bar. As an example of potential applications we performed in situ MAS NMR investigations of AlPO₄-5 molecular sieve crystallization,more » a kinetic study of the cyclohexanol dehydration reaction using 13C MAS NMR, and an investigation of the metabolomics of intact biological tissue at low temperature using 1H HR-MAS NMR spectroscopy. The in situ MAS NMR experiments performed using the reported rotors allowed reproduction of the results from traditional batch reactions, while offering more detailed quantitative information at the molecular level, as demonstrated for the molecular sieve synthesis and activation energy measurements for cyclohexanol dehydration. The perfectly sealed rotor also shows promising application for metabolomics studies using 1H HR-MAS NMR.« less

  2. Sealed rotors for in situ high temperature high pressure MAS NMR

    SciTech Connect

    Hu, Jian Z.; Hu, Mary Y.; Zhao, Zhenchao; Xu, Souchang; Vjunov, Aleksei; Shi, Hui; Camaioni, Donald M.; Peden, Charles H. F.; Lercher, Johannes A.

    2015-07-06

    Magic angle spinning (MAS) nuclear magnetic resonance (NMR) investigations on heterogeneous samples containing solids, semi-solids, liquid and gases or a mixture of them under non-conventional conditions of a combined high pressure and high temperature, or cold temperature suffer from the unavailability of a perfectly sealed rotor. Here, we report the design of reusable and perfectly-sealed all-zircornia MAS rotors. The rotors are easy to use and are suitable for operation temperatures from below 0 to 250 °C and pressures up to 100 bar. As an example of potential applications we performed in situ MAS NMR investigations of AlPO₄-5 molecular sieve crystallization, a kinetic study of the cyclohexanol dehydration reaction using 13C MAS NMR, and an investigation of the metabolomics of intact biological tissue at low temperature using 1H HR-MAS NMR spectroscopy. The in situ MAS NMR experiments performed using the reported rotors allowed reproduction of the results from traditional batch reactions, while offering more detailed quantitative information at the molecular level, as demonstrated for the molecular sieve synthesis and activation energy measurements for cyclohexanol dehydration. The perfectly sealed rotor also shows promising application for metabolomics studies using 1H HR-MAS NMR.

  3. Hydrophobization of epoxy nanocomposite surface with 1H,1H,2H,2H-perfluorooctyltrichlorosilane for superhydrophobic properties

    NASA Astrophysics Data System (ADS)

    Psarski, Maciej; Marczak, Jacek; Celichowski, Grzegorz; Sobieraj, Grzegorz B.; Gumowski, Konrad; Zhou, Feng; Liu, Weimin

    2012-10-01

    Nature inspires the design of synthetic materials with superhydrophobic properties, which can be used for applications ranging from self-cleaning surfaces to microfluidic devices. Their water repellent properties are due to hierarchical (micrometer- and nanometre-scale) surface morphological structures, either made of hydrophobic substances or hydrophobized by appropriate surface treatment. In this work, the efficiency of two surface treatment procedures, with a hydrophobic fluoropolymer, synthesized and deposited from 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) is investigated. The procedures involved reactions from the gas and liquid phases of the PFOTS/hexane solutions. The hierarchical structure is created in an epoxy nanocomposite surface, by filling the resin with alumina nanoparticles and micron-sized glass beads and subsequent sandblasting with corundum microparticles. The chemical structure of the deposited fluoropolymer was examined using XPS spectroscopy. The topography of the modified surfaces was characterized using scanning electron microscopy (SEM), and atomic force microscopy (AFM). The hydrophobic properties of the modified surfaces were investigated by water contact and sliding angles measurements. The surfaces exhibited water contact angles of above 150° for both modification procedures, however only the gas phase modification provided the non-sticking behaviour of water droplets (sliding angle of 3°). The discrepancy is attributed to extra surface roughness provided by the latter procedure.

  4. One dimensional 1H, 2H and 3H

    NASA Astrophysics Data System (ADS)

    Vidal, A. J.; Astrakharchik, G. E.; Vranješ Markić, L.; Boronat, J.

    2016-05-01

    The ground-state properties of one-dimensional electron-spin-polarized hydrogen 1H, deuterium 2H, and tritium 3H are obtained by means of quantum Monte Carlo methods. The equations of state of the three isotopes are calculated for a wide range of linear densities. The pair correlation function and the static structure factor are obtained and interpreted within the framework of the Luttinger liquid theory. We report the density dependence of the Luttinger parameter and use it to identify different physical regimes: Bogoliubov Bose gas, super-Tonks–Girardeau gas, and quasi-crystal regimes for bosons; repulsive, attractive Fermi gas, and quasi-crystal regimes for fermions. We find that the tritium isotope is the one with the richest behavior. Our results show unambiguously the relevant role of the isotope mass in the properties of this quantum system.

  5. Detailed Studies of Hydrocarbon Radicals: C2H Dissociation

    SciTech Connect

    Wittig, Curt

    2014-10-06

    A novel experimental technique was examined whose goal was the ejection of radical species into the gas phase from a platform (film) of cold non-reactive material. The underlying principle was one of photo-initiated heat release in a stratum that lies below a layer of CO2 or a layer of amorphous solid water (ASW) and CO2. A molecular precursor to the radical species of interest is deposited near or on the film's surface, where it can be photo-dissociated. It proved unfeasible to avoid the rampant formation of fissures, as opposed to large "flakes." This led to many interesting results, but resulted in our aborting the scheme as a means of launching cold C2H radical into the gas phase. A journal article resulted that is germane to astrophysics but not combustion chemistry.

  6. 2H NMR studies of supercooled and glassy aspirin

    NASA Astrophysics Data System (ADS)

    Nath, R.; Nowaczyk, A.; Geil, B.; Bohmer, R.

    2007-11-01

    Acetyl salicylic acid, deuterated at the methyl group, was investigated using 2H-NMR in its supercooled and glassy states. Just above the glass transition temperature the molecular reorientations were studied using stimulated-echo spectroscopy and demonstrated a large degree of similarity with other glass formers. Deep in the glassy phase the NMR spectra look similar to those reported for the crystal [A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z. Olejniczak, Z. T. Lalowicz, Z. Naturforsch. A 50 (1995) 95] and below 20 K they are indicative for rotational tunneling with a relatively large tunneling frequency. Measurements of the spin-lattice relaxation times for temperatures below 150 K reveal a broad distribution of correlation times in the glass. The dominant energy barrier characterizing the slow-down of the methyl group is significantly smaller than the well defined barrier in the crystal.

  7. Study of the $\\tau^- to 3h^- 2h^+ \

    SciTech Connect

    Aubert, Bernard; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Tisserand, V.; Zghiche, A.; Grauges, E.; Palano, A.; Pappagallo, M.; Pompili, A.; Chen, J.C.; Qi, N.D.; Rong, G.; Wang, P.; Zhu, Y.S.; Eigen, G.; Ofte, I.; Stugu, B. /more authors..

    2005-05-04

    The branching fraction of the {tau}{sup -} {yields} 3h{sup -} 2h{sup +} {nu}{sub {tau}} decay (h = {pi}, K) is measured with the BABAR detector to be (8.56 {+-} 0.05 {+-} 0.42) x 10{sup -4}, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the {rho} resonance playing a strong role. The decay {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -}{nu}{sub {tau}}, with the f{sub 1}(1285) meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9 {+-} 0.7 {+-} 0.5) x 10{sup -4}.

  8. The ultraviolet spectrum of Herbig-Haro object 2H

    NASA Technical Reports Server (NTRS)

    Brugel, E. W.; Seab, C. G.; Shull, J. M.

    1982-01-01

    IUE spectra of Herbig-Haro object 2H are presented. The spectra show a strong 'excess' UV continuum and prominent emission lines of C, N, O, Si, Mg, and possibly Al. The continuum, F(lambda), exhibits a turnover shortward of about 1450 A, confirming for the first time the H0 two-photon nature of the emission source. A possible absorption feature near 1680 A, which could result from a new grain or molecular constituent in these protostellar objects is also noted. Recently computed models of steady shocks into partially ionized gas reproduce the two-photon spectral shape, but its observed intensity relative to H-beta and the Balmer continuum is anomalously high. It is suggested that a range of shock velocities, 70-100 km/s, or nonsteady, 'truncated' shocks may be responsible. Future high-sensitivity UV observations of HH objects may be used to probe grain extinction curves in star-forming regions.

  9. Doping dependent plasmon dispersion in 2 H -transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Müller, Eric; Büchner, Bernd; Habenicht, Carsten; König, Andreas; Knupfer, Martin; Berger, Helmuth; Huotari, Simo

    2016-07-01

    We report the behavior of the charge carrier plasmon of 2 H -transition metal dichalcogenides (TMDs) as a function of intercalation with alkali metals. Intercalation and concurrent doping of the TMD layers have a substantial impact on plasmon energy and dispersion. While the plasmon energy shifts are related to the intercalation level as expected within a simple homogeneous electron gas picture, the plasmon dispersion changes in a peculiar manner independent of the intercalant and the TMD materials. Starting from a negative dispersion, the slope of the plasmon dispersion changes sign and grows monotonously upon doping. Quantitatively, the increase of this slope depends on the orbital character (4 d or 5 d ) of the conduction bands, which indicates a decisive role of band structure effects on the plasmon behavior.

  10. 2H and 18O Freshwater Isoscapes of Scotland

    NASA Astrophysics Data System (ADS)

    Meier-Augenstein, Wolfram; Hoogewerff, Jurian; Kemp, Helen; Frew, Danny

    2013-04-01

    Scotland's freshwater lochs and reservoirs provide a vital resource for sustaining biodiversity, agriculture, food production as well as for human consumption. Regular monitoring of freshwaters by the Scottish Environment Protection Agency (SEPA) fulfils legislative requirements with regards to water quality but new scientific methods involving stable isotope analysis present an opportunity combining these mandatory monitoring schemes with fundamental research to inform and deliver on current and nascent government policies [1] through gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and food security. For example, 2H and 18O isoscapes of Scottish freshwater could be used to underpin research and its applications in: • Climate change - Using longitudinal changes in the characteristic isotope composition of freshwater lochs and reservoirs as proxy, isoscapes will provide a means to assess if and how changes in temperature and weather patterns might impact on precipitation patterns and amount. • Scottish branding - Location specific stable isotope signatures of Scottish freshwater have the potential to be used as a tool for provenancing and thus protecting premium Scottish produce such as Scottish beef, Scottish soft fruit and Scottish Whisky. During 2011 and 2012, with the support of SEPA more than 110 samples from freshwater lochs and reservoirs were collected from 127 different locations across Scotland including the Highlands and Islands. Here we present the results of this sampling and analysis exercise isotope analyses in form of 2H and 18O isoscapes with an unprecedented grid resolution of 26.5 × 26.5 km (or 16.4 × 16.4 miles). [1] Adaptation Framework - Adapting Our Ways: Managing Scotland's Climate Risk (2009): Scotland's Biodiversity: It's in Your Hands - A strategy for the conservation and enhancement of biodiversity in Scotland (2005); Recipe For Success - Scotland

  11. Polarized Cold Neutron Capture in ^27Al

    NASA Astrophysics Data System (ADS)

    Balascuta, Septimiu

    2013-04-01

    The NPDGamma Experiment at the Spallation Neutron Source at ORNL is measuring the parity-odd correlation between the neutron spin and the direction of the emitted photon in the capture of cold neutrons on a 16-liter liquid parahydrogen target. The goal is to determine the strength of the weak nucleon-nucleon interaction. One of the main background contributions comes from the gamma rays produced by neutrons captured in the Al walls of the target vessel. To quantify this effect a commissioning experiment measured the parity-odd and parity-even asymmetries in the angular distribution of the gamma rays from the capture of polarized cold neutrons in a solid Al target. A status of the analysis of this experiment will be presented.

  12. Breakup of the projectile in [sup 16]O-induced reactions on [sup 27]Al, [sup 58]Ni, and [sup 197]Au targets around 100 MeV/nucleon

    SciTech Connect

    Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S. ); Riggi, F. Dipartimento di Fisica dell'Universita di Catania, Corso Italia 57, 95129 Catania )

    1993-08-01

    The spatial correlation among the four He ions coming from the disassembly of the [sup 16]O projectile on [sup 27]Al, [sup 58]Ni, and [sup 197]Au targets has been studied at 94 MeV/nucleon. Charged particles have been detected by a multielement array of plastic scintillators covering the angular domain between 3[degree] and 150[degree]. Standard relativistic kinematics has been used to reconstruct the excitation energy of the primary projectilelike nucleus ([ital E][sub PLN][sup *]). Mean values of this quantity are found independent of the target mass and the comparison with existing similar data taken at lower bombarding energies shows a saturation of [ital E][sub PLN][sup *] around 3 MeV/nucleon. An event-by-event analysis has been performed in order to study the distributions of some global variables such as coplanarity, sphericity, and relative angle, helpful in the understanding of the topological characteristics of the process and in the evaluation of its time scale. Experimental data have also been compared with the results of Monte Carlo simulations based on different reaction mechanisms and it is possible to conclude that sequential emission of the fragments is preferred.

  13. Exclusive studies of 130-270 MeV {sup 3}He- and 200-MeV proton-induced reactions on {sup 27}Al, {sup nat}Ag, and {sup 197}Au

    SciTech Connect

    Ginger, D. S.; Kwiatkowski, K.; Wang, G.; Hsi, W.-C.; Hudan, S.; Cornell, E.; Souza, R. T. de; Viola, V. E.; Korteling, R. G.

    2008-09-15

    Exclusive light-charged-particle and IMF spectra have been measured with the ISiS detector array for bombardments of {sup 27}Al, {sup nat}Ag, and {sup 197}Au nuclei with 130-270-MeV {sup 3}He and 200-MeV protons. The results are consistent with previous interpretations based on inclusive data that describe the global yield of complex fragments in terms of a time-dependent process. The emission mechanism for energetic nonequilibrium fragments observed at forward angles with momenta up to twice the beam momentum is also investigated. This poorly understood mechanism, for which the angular distributions indicate formation on a time scale comparable to the nuclear transit time, are accompanied primarily by thermal-like emissions. The data are most consistent with a schematic picture in which nonequilibrium fragments are formed in a localized region of the target nucleus at an early stage in the energy-dissipation process, where the combined effects of high energy density and Fermi motion produce the observed suprathermal spectra.

  14. Study of the peripheral projectile-like fragments from the reaction {sup 129}Xe on {sup 27}Al, {sup nat}Cu, {sup 139}La and {sup 165}Ho, at E/A = 50 MeV

    SciTech Connect

    Garcia-Solis, E.J.; Russ, D.E.; Madani, H.

    1996-02-01

    There are several reaction mechanisms identified for peripheral heavy-ion collisions. For low bombarding energies (E/A {approx} 10 MeV) the predominant reaction channel is the deep-inelastic reaction mechanism. In this process, the projectile and target form a rotating binary system, interchanging nucleons and angular momentum until they separate. At higher bombarding energies (E/A {approx} 50 to 100 MeV) incomplete fusion is thought to be the prevailing reaction channel. In this type of interaction part of the projectile merges with the target during the collision. Finally, for energies greater than 100 MeV/A, the main reaction channel is characterized by the formation of a highly-excited separate fragment (fireball) produced during the overlap between the projectile and the target. The data set studied was from an experiment designed to characterize the projectile-like products of the {sup 27}Al, {sup nat}Cu, {sup 139}La, and {sup 165}Ho reactions at E/A = 50 MeV, which was performed at the Michigan State University Super Cyclotron Laboratory (MSU-NSCL). The Maryland Forward Array (MFA), was used to measure projectile-like fragments in coincidence with target-like fragments and light-charge particles in the MSU 4{pi} detector.

  15. Citron and lemon under the lens of HR-MAS NMR spectroscopy.

    PubMed

    Mucci, Adele; Parenti, Francesca; Righi, Valeria; Schenetti, Luisa

    2013-12-01

    High Resolution Magic Angle Spinning (HR-MAS) is an NMR technique that can be applied to semi-solid samples. Flavedo, albedo, pulp, seeds, and oil gland content of lemon and citron were studied through HR-MAS NMR spectroscopy, which was used directly on intact tissue specimens without any physicochemical manipulation. HR-MAS NMR proved to be a very suitable technique for detecting terpenes, sugars, organic acids, aminoacids and osmolites. It is valuable in observing changes in sugars, principal organic acids (mainly citric and malic) and ethanol contents of pulp specimens and this strongly point to its use to follow fruit ripening, or commercial assessment of fruit maturity. HR-MAS NMR was also used to derive the molar percentage of fatty acid components of lipids in seeds, which can change depending on the Citrus species and varieties. Finally, this technique was employed to elucidate the metabolic profile of mold flavedo. PMID:23871074

  16. Cassini's Maneuver Automation Software (MAS) Process: How to Successfully Command 200 Navigation Maneuvers

    NASA Technical Reports Server (NTRS)

    Yang, Genevie Velarde; Mohr, David; Kirby, Charles E.

    2008-01-01

    To keep Cassini on its complex trajectory, more than 200 orbit trim maneuvers (OTMs) have been planned from July 2004 to July 2010. With only a few days between many of these OTMs, the operations process of planning and executing the necessary commands had to be automated. The resulting Maneuver Automation Software (MAS) process minimizes the workforce required for, and maximizes the efficiency of, the maneuver design and uplink activities. The MAS process is a well-organized and logically constructed interface between Cassini's Navigation (NAV), Spacecraft Operations (SCO), and Ground Software teams. Upon delivery of an orbit determination (OD) from NAV, the MAS process can generate a maneuver design and all related uplink and verification products within 30 minutes. To date, all 112 OTMs executed by the Cassini spacecraft have been successful. MAS was even used to successfully design and execute a maneuver while the spacecraft was in safe mode.

  17. BOREAS Level-2 MAS Surface Reflectance and Temperature Images in BSQ Format

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Newcomer, Jeffrey (Editor); Lobitz, Brad; Spanner, Michael; Strub, Richard; Lobitz, Brad

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study (BOREAS) Staff Science Aircraft Data Acquisition Program focused on providing the research teams with the remotely sensed aircraft data products they needed to compare and spatially extend point results. The MODIS Airborne Simulator (MAS) images, along with other remotely sensed data, were collected to provide spatially extensive information over the primary study areas. This information includes biophysical parameter maps such as surface reflectance and temperature. Collection of the MAS images occurred over the study areas during the 1994 field campaigns. The level-2 MAS data cover the dates of 21-Jul-1994, 24-Jul-1994, 04-Aug-1994, and 08-Aug-1994. The data are not geographically/geometrically corrected; however, files of relative X and Y coordinates for each image pixel were derived by using the C130 navigation data in a MAS scan model. The data are provided in binary image format files.

  18. BOREAS Level-1B MAS Imagery At-sensor Radiance, Relative X and Y Coordinates

    NASA Technical Reports Server (NTRS)

    Strub, Richard; Strub, Richard; Newcomer, Jeffrey A.; Ungar, Stephen

    2000-01-01

    For BOReal Ecosystem-Atmosphere Study (BOREAS), the MODIS Airborne Simulator (MAS) images, along with the other remotely sensed data, were collected to provide spatially extensive information over the primary study areas. This information includes detailed land cover and biophysical parameter maps such as fraction of Photosynthetically Active Radiation (fPAR) and Leaf Area Index (LAI). Collection of the MAS images occurred over the study areas during the 1994 field campaigns. The level-1b MAS data cover the dates of 21-Jul-1994, 24-Jul-1994, 04-Aug-1994, and 08-Aug-1994. The data are not geographically/geometrically corrected; however, files of relative X and Y coordinates for each image pixel were derived by using the C-130 INS data in a MAS scan model. The data are provided in binary image format files.

  19. Comparing the Effects of Lovastatin and Cornus Mas Fruit on Fibrinogen Level in Hypercholesterolemic Rabbits

    PubMed Central

    Asgary, Sedigheh; Rafieian-Kopaei, Mahmoud; Adelnia, Azadeh; Kazemi, Somayeh; Shamsi, Fatemeh

    2010-01-01

    BACKGROUND Atherosclerosis, which is a result of gradual deposition of lipids in the lower part of blood vessel endothelium, is the leading cause of mortality and morbidity around the world. It has been proved that some inflammatory blood markers such as fibrinogen can predict the risk for cardiovascular disease conditions, not only in cardiovascular patients, but also in those who do not have any manifestations of the atherosclerotic development. In this study, the effect of cornus mas l. was evaluated on fibrinogen of hypercholesterolemic rabbits and it was also compared with lovastatin drug. METHODS In this study, 25 New Zealand adult male rabbits were randomly divided into five groups of five. They were treated for 60 days by 5 different diets, namely basic, high cholesterol, regular plus 1 g/kgBW cornus mas L. powder, high cholesterol plus 1 g/kgBW cornus mas L. powder, and high cholesterol plus 10 mg/kgBW lovastatin. At the beginning and at the end of this period, blood samples were collected from the rabbits and their serum fibrinogen levels were measured. RESULTS Cornus mas L. powder and lovastatin significantly decreased fibrinogen levels in comparison with high cholesterol group (P < 0.05). Furthermore cornus mas L. powder could reduce the fibrinogen level more than lovastatin (P < 0.05). CONCLUSION The results indicated that consumption of cornus mas L. might be beneficial in atherosclerotic patients due to its reducing effects on fibrinogen. PMID:22577405

  20. A Novel α/β-Hydrolase Gene IbMas Enhances Salt Tolerance in Transgenic Sweetpotato

    PubMed Central

    Song, Xuejin; He, Shaozhen; Liu, Qingchang

    2014-01-01

    Salt stress is one of the major environmental stresses in agriculture worldwide and affects crop productivity and quality. The development of crops with elevated levels of salt tolerance is therefore highly desirable. In the present study, a novel maspardin gene, named IbMas, was isolated from salt-tolerant sweetpotato (Ipomoea batatas (L.) Lam.) line ND98. IbMas contains maspardin domain and belongs to α/β-hydrolase superfamily. Expression of IbMas was up-regulated in sweetpotato under salt stress and ABA treatment. The IbMas-overexpressing sweetpotato (cv. Shangshu 19) plants exhibited significantly higher salt tolerance compared with the wild-type. Proline content was significantly increased, whereas malonaldehyde content was significantly decreased in the transgenic plants. The activities of superoxide dismutase (SOD) and photosynthesis were significantly enhanced in the transgenic plants. H2O2 was also found to be significantly less accumulated in the transgenic plants than in the wild-type. Overexpression of IbMas up-regulated the salt stress responsive genes, including pyrroline-5-carboxylate synthase, pyrroline-5-carboxylate reductase, SOD, psbA and phosphoribulokinase genes, under salt stress. These findings suggest that overexpression of IbMas enhances salt tolerance of the transgenic sweetpotato plants by regulating osmotic balance, protecting membrane integrity and photosynthesis and increasing reactive oxygen species scavenging capacity. PMID:25501819

  1. The Consistency of the Pandemic Simulations between the SEIR Model and the MAS Model

    NASA Astrophysics Data System (ADS)

    Toyosaka, Yuki; Hirose, Hideo

    There are two main methods for pandemic simulations: the SEIR model and the MAS model. The SEIR model can deal with simulations quickly for many homogeneous populations with simple ordinary differential equations; however, the model cannot accommodate many detailed conditions. The MAS model, the multi-agent simulation, can deal with detailed simulations under the many kinds of initial and boundary conditions with simple social network models. However, the computing cost will grow exponentially as the population size becomes larger. Thus, simulations in the large-scale model would hardly be realized unless supercomputers are available. By combining these two methods, we may perform the pandemic simulations in the large-scale model with lower costs. That is, the MAS model is used in the early stage of a pandemic simulation to determine the appropriate parameters to be used in the SEIR model. With these obtained parameters, the SEIR model may then be used. To investigate the validity of this combined method, we first compare the simulation results between the SEIR model and the MAS model. Simulation results of the MAS model and the SEIR model that uses the parameters obtained by the MAS model simulation are found to be close to each other.

  2. 2F and 2H evaporator loop evaluation closure report

    SciTech Connect

    Bates, W.F.

    1994-01-28

    As a result of the Concentrate Transfer System (CTS) tank ventilation system contamination event, a task team was formed to evaluate instrument loops associated with waste reduction equipment. During the event a conductivity probe designed to provide an alarm and initiate an interlock failed to respond to the presence of liquid. An investigation revealed that the probe had become disconnected from the loop. The daily functional check of the conductivity probe circuit only tested the circuit continuity from the ventilation unit to the control room and did not actually test the probe. To test the continuity, a test switch was used to simulate the conducting probe. Because the functional check did not test each part of the loop, the test could be satisfactorily completed even though the probe itself was inoperable. The function of the task team was to develop a list of loops and interlocks prioritized by importance and likelihood of similar failure. The team evaluated the associated loop calibration and functional test procedures to verify that they are adequate to ensure loop performance on a periodic frequency. This report documents the evaluation findings and associated actions required prior to startup of the 2F and 2H evaporators.

  3. Ca2+/H+ exchange in acidic vacuoles of Trypanosoma brucei.

    PubMed Central

    Vercesi, A E; Moreno, S N; Docampo, R

    1994-01-01

    The use of digitonin to permeabilize the plasma membrane of Trypanosoma brucei procyclic and bloodstream trypomastigotes allowed the identification of a non-mitochondrial nigericin-sensitive Ca2+ compartment. The proton ionophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) was able to cause Ca2+ release from this compartment, which was also sensitive to sodium orthovanadate. Preincubation of the cells with the vacuolar H(+)-ATPase inhibitor bafilomycin A1 greatly reduced the nigericin-sensitive Ca2+ compartment. Bafilomycin A1 inhibited the initial rate of ATP-dependent non-mitochondrial Ca2+ uptake and stimulated the initial rate of nigericin-induced Ca2+ release by permeabilized procyclic trypomastigotes. ATP-dependent and bafilomycin A1- and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl)-sensitive Acridine Orange uptake was demonstrated in permeabilized cells. Under these conditions Acridine Orange was concentrated in abundant cytoplasmic round vacuoles by a process inhibited by bafilomycin A1, NBD-Cl, nigericin, and Ca2+. Vanadate or EGTA significantly increased Acridine Orange uptake, while Ca2+ released Acridine Orange from these preparations, thus suggesting that the dye and Ca2+ were being accumulated in the same acidic vacuole. Acridine Orange uptake was reversed by nigericin, bafilomycin A1 and NH4Cl. The results are consistent with the presence of a Ca2+/H(+)-ATPase system pumping Ca2+ into an acidic vacuole, that we tentatively named the acidocalcisome. Images Figure 5 PMID:7998937

  4. Model dependence of the {sup 2}H electric dipole moment

    SciTech Connect

    Afnan, I. R.; Gibson, B. F.

    2010-12-15

    Background: Direct measurement of the electric dipole moment (EDM) of the neutron is in the future; measurement of a nuclear EDM may well come first. The deuteron is one nucleus for which exact model calculations are feasible. Purpose: We explore the model dependence of deuteron EDM calculations. Methods: Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variation in the nucleon-nucleon interaction. We write the EDM as the sum of two terms, the first depending on the target wave function with plane-wave intermediate states, and the second depending on intermediate multiple scattering in the {sup 3}P{sub 1} channel, the latter being sensitive to the off-shell behavior of the {sup 3}P{sub 1} amplitude. Results: We compare the full calculation with the plane-wave approximation result, examine the tensor force contribution to the model results, and explore the effect of short-range repulsion found in realistic, contemporary potential models of the deuteron. Conclusions: Because one-pion exchange dominates the EDM calculation, separable potential model calculations will provide an adequate description of the {sup 2}H EDM until such time as a measurement better than 10% is obtained.

  5. Electron paramagnetic resonance spectra and structures of Cu(C sub 2 H sub 4 ), Cu(C sub 2 H sub 4 ) sub 2 , and Cu(C sub 2 H sub 4 ) sub 3 in hydrocarbon matrices

    SciTech Connect

    Howard, J.A.; Joly, H.A.; Mile, B. )

    1990-02-22

    Two mononuclear {pi}-complexes, Cu(C{sub 2}H{sub 4}) and Cu(C{sub 2}H{sub 4}){sub 2}, have been positively identified by EPR spectroscopy from reaction of Cu atoms and ethylene at 77 K in inert hydrocarbon matrices on a rotating cryostat. The spectra of these copper(O) complexes are consistent with dative bonding for both species and with a C{sub 2v} structure for Cu(C{sub 2}H{sub 4}) and a D{sub 2h} structure for Cu(C{sub 2}H{sub 4}){sub 2}. Spectra of Cu({sup 13}CH{sub 2}CH{sub 2}) and Cu({sup 13}CH{sub 2}CH{sub 2}){sub 2} are consistent with these assignments. A third complex is formed in both adamantane and cyclohexane that could be Cu(C{sub 2}H{sub 4}){sub 2} with a structure other than D{sub 2h} but is more likely to be the mononuclear trisligand complex Cu(C{sub 2}H{sub 4}){sub 3} with a D{sub 3h} structure. In the absence of a well-resolved isotropic spectrum of Cu({sup 13}CH{sub 2}CH{sub 2}){sub 3}, this assignment must however be taken as tentative.

  6. Global distributions of C2H6, C2H2, HCN, and PAN retrieved from MIPAS reduced spectral resolution measurements

    NASA Astrophysics Data System (ADS)

    Wiegele, A.; Glatthor, N.; Höpfner, M.; Grabowski, U.; Kellmann, S.; Linden, A.; Stiller, G.; von Clarmann, T.

    2011-08-01

    Vertical profiles of mixing ratios of C2H6, C2H2, HCN, and PAN were retrieved from MIPAS reduced spectral resolution nominal mode limb emission measurements. The retrieval strategy followed that of the analysis of MIPAS high resolution measurements, with occasional adjustments to cope with the reduced spectral resolution under which MIPAS is operated since 2005. Largest mixing ratios are found in the troposphere, and reach 1.2 ppbv for C2H6, 1 ppbv for HCN, 600 pptv for PAN, and 450 pptv for C2H2. The estimated precision in case of significantly enhanced mixing ratios (including measurement noise and propagation of uncertain parameters randomly varying in the time domain) and altitude resolution are typically 10 %, 3-4.5 km for C2H6, 15 %, 4-6 km for HCN, 6 %, 2.5-3.5 km for PAN, and 7 %, 2.5-4 km for C2H2.

  7. Full-dimensional quantum dynamics study of the H2 + C2H → H + C2H2 reaction on an ab initio potential energy surface.

    PubMed

    Chen, Liuyang; Shao, Kejie; Chen, Jun; Yang, Minghui; Zhang, Dong H

    2016-05-21

    This work performs a time-dependent wavepacket study of the H2 + C2H → H + C2H2 reaction on a new ab initio potential energy surface (PES). The PES is constructed using neural network method based on 68 478 geometries with energies calculated at UCCSD(T)-F12a/aug-cc-pVTZ level and covers H2 + C2H↔H + C2H2, H + C2H2 → HCCH2, and HCCH2 radial isomerization reaction regions. The reaction dynamics of H2 + C2H → H + C2H2 are investigated using full-dimensional quantum dynamics method. The initial-state selected reaction probabilities are calculated for reactants in eight vibrational states. The calculated results showed that the H2 vibrational excitation predominantly enhances the reactivity while the excitation of bending mode of C2H slightly inhibits the reaction. The excitations of two stretching modes of C2H molecule have negligible effect on the reactivity. The integral cross section is calculated with J-shift approximation and the mode selectivity in this reaction is discussed. The rate constants over 200-2000 K are calculated and agree well with the experimental measured values. PMID:27208951

  8. Ion-neutral reaction of the C2H2N+ cation with C2H2: An experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Fathi, P.; Geppert, W. D.; Kaiser, A.; Ascenzi, D.

    2016-03-01

    The ion-neutral reactions of the C2H2N+ cation with C2H2 have been investigated using a Guided Ion Beam Mass Spectrometer (GIB-MS). The following ionic products were observed: CH3+, C2H2+, C2H3+, HNC+ /HCN+ , HCNH+, C3H+ , C2N+ , C3H3+, HCCN+ and C4H2N+ . Theoretical calculations have been carried out to propose reaction pathways leading to the observed products. These processes are of relevance for the generation of long chain nitrogen-containing species and they may be of interest for the chemistry of Titan's ionosphere or circumstellar envelopes.

  9. Theoretical study of the C-H bond dissociation energies of CH4, C2H2, C2H4, and H2C2O

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1991-01-01

    The successive C-H bond dissociation energies of CH4, C2H2, C2H4, and H2C2O (ketene) are determined using large-basis sets and a high level of correlation treatment. For CH4, C2H2, and C2H4 the computed values are in excellent agreement with experiment. Using these results, the values 107.9 + or - 2.0 and 96.7 + or - 2.0 kcal/mol are recommended for the C-H bond dissociation energies of H2C2O and HC2O, respectively.

  10. Full-dimensional quantum dynamics study of the H2 + C2H → H + C2H2 reaction on an ab initio potential energy surface

    NASA Astrophysics Data System (ADS)

    Chen, Liuyang; Shao, Kejie; Chen, Jun; Yang, Minghui; Zhang, Dong H.

    2016-05-01

    This work performs a time-dependent wavepacket study of the H2 + C2H → H + C2H2 reaction on a new ab initio potential energy surface (PES). The PES is constructed using neural network method based on 68 478 geometries with energies calculated at UCCSD(T)-F12a/aug-cc-pVTZ level and covers H2 + C2H↔H + C2H2, H + C2H2 → HCCH2, and HCCH2 radial isomerization reaction regions. The reaction dynamics of H2 + C2H → H + C2H2 are investigated using full-dimensional quantum dynamics method. The initial-state selected reaction probabilities are calculated for reactants in eight vibrational states. The calculated results showed that the H2 vibrational excitation predominantly enhances the reactivity while the excitation of bending mode of C2H slightly inhibits the reaction. The excitations of two stretching modes of C2H molecule have negligible effect on the reactivity. The integral cross section is calculated with J-shift approximation and the mode selectivity in this reaction is discussed. The rate constants over 200-2000 K are calculated and agree well with the experimental measured values.

  11. Electron capture processes in Li2+ + H collisions

    NASA Astrophysics Data System (ADS)

    Yan, Ling Ling; Liu, Ling; Wang, Jian Guo; Janev, Ratko K.; Buenker, Robert J.

    2015-01-01

    The electron capture processes in Li2 + + H collisions have been investigated by using the quantum-mechanical molecular-orbital close-coupling method and the two-center atomic-orbital close-coupling method in the energy ranges of 10-8-10 keV/u and 0.1-300 keV/u, respectively. The capture to singlet and triplet systems of states of Li+(1 s,n l 2S + 1L) is considered separately. Total, n,S-resolved and n,l,S-resolved electron capture cross sections are calculated and compared with the results of available experimental and theoretical studies. The present calculations show that the n = 2 shell of Li+ is the main capture channel for all energies considered in both the singlet and triplet case. While for collision energies E> 5 keV/u, the cross sections for capture to the n = 2 manifold are of the same order of magnitude for both the singlet and triplet states (with the 2 p capture cross section being dominant), for energies below ~5 keV/u the cross sections for capture to the n = 2 triplet manifold is significantly (more than three orders of magnitude at 0.1 keV/u) larger than that for capture to the n = 2 singlet manifold of states (with the 2 s capture cross section being dominant). The capture dynamics at low collision energies is discussed in considerable detail, revealing the important role of rotational couplings in population of l> 0 capture states. The elastic scattering processes have been studied as well in the energy range of 10-8-1 keV/u. The calculated elastic scattering cross section is much larger than the electron capture cross section in both the singlet and triplet case. However, as the collision energy increases, the difference between the elastic and electron capture cross sections decreases rapidly.

  12. High/variable mixture ratio O2/H2 engine

    NASA Technical Reports Server (NTRS)

    Adams, A.; Parsley, R. C.

    1988-01-01

    Vehicle/engine analysis studies have identified the High/Dual Mixture Ratio O2/H2 Engine cycle as a leading candidate for an advanced Single Stage to Orbit (SSTO) propulsion system. This cycle is designed to allow operation at a higher than normal O/F ratio of 12 during liftoff and then transition to a more optimum O/F ratio of 6 at altitude. While operation at high mixture ratios lowers specific impulse, the resultant high propellant bulk density and high power density combine to minimize the influence of atmospheric drag and low altitude gravitational forces. Transition to a lower mixture ratio at altitude then provides improved specific impulse relative to a single mixture ratio engine that must select a mixture ratio that is balanced for both low and high altitude operation. This combination of increased altitude specific impulse and high propellant bulk density more than offsets the compromised low altitude performance and results in an overall mission benefit. Two areas of technical concern relative to the execution of this dual mixture ratio cycle concept are addressed. First, actions required to transition from high to low mixture ratio are examined, including an assessment of the main chamber environment as the main chamber mixture ratio passes through stoichiometric. Secondly, two approaches to meet a requirement for high turbine power at high mixture ratio condition are examined. One approach uses high turbine temperature to produce the power and requires cooled turbines. The other approach incorporates an oxidizer-rich preburner to increase turbine work capability via increased turbine mass flow.

  13. High-frequency dynamic nuclear polarization in MAS spectra of membrane and soluble proteins.

    PubMed

    Rosay, Melanie; Lansing, Jonathan C; Haddad, Kristin C; Bachovchin, William W; Herzfeld, Judith; Temkin, Richard J; Griffin, Robert G

    2003-11-12

    One of the principal promises of solid-state NMR (SSNMR) magic angle spinning (MAS) experiments has been the possibility of determining the structures of molecules in states that are not accessible via X-ray or solution NMR experiments-e.g., membrane or amyloid proteins. However, the low sensitivity of SSNMR often restricts structural studies to small-model compounds and precludes many higher-dimensional solid-state MAS experiments on such systems. To address the sensitivity problem, we have developed experiments that utilize dynamic nuclear polarization (DNP) to enhance sensitivity. In this communication, we report the successful application of MAS DNP to samples of cryoprotected soluble and membrane proteins. In particular, we have observed DNP signal enhancements of up to 50 in 15N MAS spectra of bacteriorhodopsin (bR) and alpha-lytic protease (alpha-LP). The spectra were recorded at approximately 90 K where MAS is experimentally straightforward, and the results suggest that the described protocol will be widely applicable. PMID:14599177

  14. The role of angiotensin-(1–7) receptor Mas in spermatogenesis in mice and rats

    PubMed Central

    Leal, Marcelo C; Pinheiro, Sérgio V B; Ferreira, Anderson J; Santos, Robson A S; Bordoni, Leonardo S; Alenina, Natalia; Bader, Michael; França, Luiz R

    2009-01-01

    Evidence regarding the components of the renin–angiotensin (Ang) system suggests that this system plays an important role in male reproduction. However, there are few data available in the literature on the effects of Ang-(1–7) on the male reproductive system. The present study investigated the effects of the genetic deletion and chronic blockage of Ang-(1–7) receptor Mas on spermatogenesis and male fertility. The localization of Mas in mouse and rat testes was determined by binding assays and immunofluorescence, whereas the testis structure and spermatogenic process were morphologically and stereologically analysed by light microscopy. Ang-(1–7) binding and immunofluorescence revealed the presence of Mas in the testes of mice and rats. Although the total numbers of Sertoli and Leydig cells per testis and Leydig cell size were similar in both wild-type and Mas-deficient mice, Mas−/– animals exhibited a significant reduction in testis weight and a greater volume of apoptotic cells, giant cells and vacuoles in the seminiferous epithelium. In both mice and rats, an increased number of apoptotic cells were found during meiosis. Due to disturbed spermatogenesis, daily sperm production was markedly reduced in Mas−/– mice. Moreover, chronic infusion of A-779 [an Ang-(1–7) antagonist] in rats significantly increased the total number of apoptotic cells and primary spermatocytes in particular stages of spermatogenesis. Taken together, these findings strongly suggest that Ang-(1–7) receptor Mas plays an important role in the regulation of spermatogenesis. PMID:19438767

  15. A software framework for analysing solid-state MAS NMR data.

    PubMed

    Stevens, Tim J; Fogh, Rasmus H; Boucher, Wayne; Higman, Victoria A; Eisenmenger, Frank; Bardiaux, Benjamin; van Rossum, Barth-Jan; Oschkinat, Hartmut; Laue, Ernest D

    2011-12-01

    Solid-state magic-angle-spinning (MAS) NMR of proteins has undergone many rapid methodological developments in recent years, enabling detailed studies of protein structure, function and dynamics. Software development, however, has not kept pace with these advances and data analysis is mostly performed using tools developed for solution NMR which do not directly address solid-state specific issues. Here we present additions to the CcpNmr Analysis software package which enable easier identification of spinning side bands, straightforward analysis of double quantum spectra, automatic consideration of non-uniform labelling schemes, as well as extension of other existing features to the needs of solid-state MAS data. To underpin this, we have updated and extended the CCPN data model and experiment descriptions to include transfer types and nomenclature appropriate for solid-state NMR experiments, as well as a set of experiment prototypes covering the experiments commonly employed by solid-sate MAS protein NMR spectroscopists. This work not only improves solid-state MAS NMR data analysis but provides a platform for anyone who uses the CCPN data model for programming, data transfer, or data archival involving solid-state MAS NMR data. PMID:21953355

  16. Electron swarm parameters in pure C2H2 and in C2H2-Ar mixtures and electron collision cross sections for the C2H2 molecule

    NASA Astrophysics Data System (ADS)

    Nakamura, Yoshiharu

    2010-09-01

    Electron swarm parameters (the drift velocity and the longitudinal diffusion coefficient) were measured in pure C2H2 and also in C2H2-Ar mixtures containing 0.517% and 5.06% acetylene over wide E/N ranges. These swarm parameters were analysed using a Boltzmann equation analysis and a set of electron collision cross sections for the C2H2 molecule was derived so that it was consistent with the present swarm data and published ionization coefficient. The present result suggested the presence of a Ramsauer-Townsend minimum in the elastic momentum transfer cross section at 0.08 eV and prominent threshold and resonance peaks in the ν4/ν5 vibrational excitation cross section. The present cross section set was also confirmed to be consistent with the published experimental total cross section of C2H2.

  17. Investigation of domain size in polymer membranes using double quantum filtered spin diffusion MAS NMR.

    SciTech Connect

    Fujimoto, Cy H.; Alam, Todd Michael; Cherry, Brian Ray; Cornelius, Christopher James

    2005-02-01

    Solid-state {sup 1}H magic angle spinning (MAS) NMR was used to investigate sulfonated Diels-Alder poly(phenlylene) polymer membranes. Under high spinning speed {sup 1}H MAS conditions, the proton environments of the sulfonic acid and phenylene polymer backbone are resolved. A double-quantum (DQ) filter using the rotor-synchronized back-to-back (BABA) NMR multiple-pulse sequence allowed the selective suppression of the sulfonic proton environment in the {sup 1}H MAS NMR spectra. This DQ filter in conjunction with a spin diffusion NMR experiment was then used to measure the domain size of the sulfonic acid component within the membrane. In addition, the temperature dependence of the sulfonic acid spin-spin relaxation time (T{sub 2}) was determined, providing an estimate of the activation energy for the proton dynamics of the dehydrated membrane.

  18. Line shapes in CP/MAS NMR spectra of half-integer quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Hayashi, Shigenobu; Hayamizu, Kikuko

    1993-02-01

    Cross polarization (CP) from 1H to quadrupolar nuclei with S = 3/2 has been carried out under magic-angle-spinning (MAS) conditions for powder samples of Na 2B 4O 7·10H 2O and H 3BO 3. The line shapes in the CP/MAS NMR spectra are different from those in the spectra measured with the single pulse sequence combined with 1H dipolar decoupling. Furthermore, the line shapes are found to be dependent on the measuring conditions such as the pulse amplitude for the quadrupolar nuclei. The spin-locking experiments demonstrate that line shapes in CP/MAS NMR spectra are largely dependent on the spin-locking efficiency.

  19. Technology Enhanced Learning for People with Intellectual Disabilities and Cerebral Paralysis: The MAS Platform

    NASA Astrophysics Data System (ADS)

    Colomo-Palacios, Ricardo; Paniagua-Martín, Fernando; García-Crespo, Ángel; Ruiz-Mezcua, Belén

    Education for students with disabilities now takes place in a wide range of settings, thus, including a wider range of assistive tools. As a result of this, one of the most interesting application domains of technology enhanced learning is related to the adoption of learning technologies and designs for people with disabilities. Following this unstoppable trend, this paper presents MAS, a software platform aimed to help people with severe intellectual disabilities and cerebral paralysis in their learning processes. MAS, as a technology enhanced learning platform, provides several tools that supports learning and monitoring for people with special needs, including adaptative games, data processing and monitoring tools. Installed in a special needs education institution in Madrid, Spain, MAS provides special educators with a tool that improved students education processes.

  20. Central nervous system dysfunction in a mouse model of FA2H deficiency.

    PubMed

    Potter, Kathleen A; Kern, Michael J; Fullbright, George; Bielawski, Jacek; Scherer, Steven S; Yum, Sabrina W; Li, Jian J; Cheng, Hua; Han, Xianlin; Venkata, Jagadish Kummetha; Khan, P Akbar Ali; Rohrer, Bärbel; Hama, Hiroko

    2011-07-01

    Fatty acid 2-hydroxylase (FA2H) is responsible for the synthesis of myelin galactolipids containing hydroxy fatty acid (hFA) as the N-acyl chain. Mutations in the FA2H gene cause leukodystrophy, spastic paraplegia, and neurodegeneration with brain iron accumulation. Using the Cre-lox system, we developed two types of mouse mutants, Fa2h(-/-) mice (Fa2h deleted in all cells by germline deletion) and Fa2h(flox/flox) Cnp1-Cre mice (Fa2h deleted only in oligodendrocytes and Schwann cells). We found significant demyelination, profound axonal loss, and abnormally enlarged axons in the CNS of Fa2h(-/-) mice at 12 months of age, while structure and function of peripheral nerves were largely unaffected. Fa2h(-/-) mice also exhibited histological and functional disruption in the cerebellum at 12 months of age. In a time course study, significant deterioration of cerebellar function was first detected at 7 months of age. Further behavioral assessments in water T-maze and Morris water maze tasks revealed significant deficits in spatial learning and memory at 4 months of age. These data suggest that various regions of the CNS are functionally compromised in young adult Fa2h(-/-) mice. The cerebellar deficits in 12-month-old Fa2h(flox/flox) Cnp1-Cre mice were indistinguishable from Fa2h(-/-) mice, indicating that these phenotypes likely stem from the lack of myelin hFA-galactolipids. In contrast, Fa2h(flox/flox) Cnp1-Cre mice did not show reduced performance in water maze tasks, indicating that oligodendrocytes are not involved in the learning and memory deficits found in Fa2h(-/-) mice. These findings provide the first evidence that FA2H has an important function outside of oligodendrocytes in the CNS. PMID:21491498

  1. Environmental, trophic, and ecological factors influencing bone collagen δ2H

    NASA Astrophysics Data System (ADS)

    Topalov, Katarina; Schimmelmann, Arndt; David Polly, P.; Sauer, Peter E.; Lowry, Mark

    2013-06-01

    Organic deuterium/hydrogen stable isotope ratios (i.e., 2H/1H, expressed as δ2H value in ‰) in animal tissues are related to the 2H/1H in diet and ingested water. Bone collagen preserves the biochemical 2H/1H isotopic signal in the δ2H value of collagen's non-exchangeable hydrogen. Therefore, δ2H preserved in bone collagen has the potential to constrain environmental and trophic conditions, which is of interest to researchers studying of both living and fossil vertebrates. Our data examine the relationship of δ2H values of collagen with geographic variation in δ2H of meteoric waters, with local variations in the ecology and trophic level of species, and with the transition from mother's milk to adult diet. Based on 97 individuals from 22 marine and terrestrial vertebrates (predominately mammals), we found the relationships of collagen δ2H to both geographic variation in meteoric water δ2H (R2 = 0.55) and to δ15N in bone collagen (R2 = 0.17) statistically significant but weaker than previously reported. The second strongest control on collagen δ2H in our data is dietary, with nearly 50 percent of the variance in δ2H explained by trophic level (R2 = 0.47). Trophic level effects potentially confound the local meteoric signal if not held constant: herbivores tend to have the lowest δ2H values, omnivores have intermediate ones, and carnivores have the highest values. Body size (most likely related to mass-specific metabolic rates) has a strong influence on collagen δ2H (R2 = 0.30), by causing greater sensitivity in smaller animals to seasonal climate variations and/or high evapotranspiration leading to 2H-enrichment in tissues. In marine mammals weaning produces a dramatic effect on collagen δ2H with adult values being universally higher than pup values (R2 = 0.79). Interestingly, the shift in δ15N at weaning is downward, even though normally hydrogen and nitrogen isotope ratios are positively correlated with one another in respect to trophic level. Our

  2. Isotope Substitution Effect in Polyatomic Molecules on the Example of 13C2H4 ← 12C2H4 Substitution

    NASA Astrophysics Data System (ADS)

    Bekhtereva, E. S.; Gromova, O. V.; Berezkin, K. B.; Kashirina, N. V.; Konov, I. A.; Bauerecker, S.

    2016-03-01

    General points of the theory of isotope substitution are applied to an analysis of the isotope substitution effect for the substitution 13C2H4←12C2H4 in the ethylene molecule. On the basis of the isotope relations so obtained, numerical predictions of band centers and the most significant rotational, centrifugal, and resonance parameters are made here for the first time for the four lower vibrational states of the 13C2H4 molecule, which can be used to analyze the complicated vibrational-rotational structure of the above-mentioned vibrational states.

  3. Probing the aromaticity of the [(HtAc)3(μ2-H)6], [(HtTh)3(μ2-H)6],+, and [(HtPa)3(μ2-H)6] clusters

    NASA Astrophysics Data System (ADS)

    Ramírez-Tagle, Rodrigo; Alvarado-Soto, Leonor; Arratia-Perez, Ramiro; Bast, Radovan; Alvarez-Thon, Luis

    2011-09-01

    In this study we report about the aromaticity of the prototypical [(HtAc)3(μ2-H)6], [(HtTh)3(μ2-H)6]+, and [(HtPa)3(μ2-H)6] clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters [(HtAc)3(μ2-H)6] and [(HtTh)3(μ2-H)6]+ are non-aromatic whereas [(HtPa)3(μ2-H)6] is anti-aromatic. However, for the thorium cluster we find a discrepancy between the current density plots and the classification through the NICS index. Our results also demonstrate the increasing influence of f orbitals, on bonding and magnetic properties, with increasing atomic number in these clusters. We think that the enhanced electron mobility in [(HtPa)3(μ2-H)6] is due the significant 5f character of its valence shell. Also the participation of f orbitals in bonding is the reason why the protactinium cluster has the shortest bond lengths of the three clusters. This study provides another example showing that the magnetically induced current density approach can give more reliable results than the NICS index.

  4. Probing the aromaticity of the [(H(t)Ac)3(μ2-H)6], [(H(t)Th)3(μ2-H)6],(+), and [(H(t)Pa)3(μ2-H)6] clusters.

    PubMed

    Ramírez-Tagle, Rodrigo; Alvarado-Soto, Leonor; Arratia-Perez, Ramiro; Bast, Radovan; Alvarez-Thon, Luis

    2011-09-14

    In this study we report about the aromaticity of the prototypical [(H(t)Ac)(3)(μ(2)-H)(6)], [(H(t)Th)(3)(μ(2)-H)(6)](+), and [(H(t)Pa)(3)(μ(2)-H)(6)] clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters [(H(t)Ac)(3)(μ(2)-H)(6)] and [(H(t)Th)(3)(μ(2)-H)(6)](+) are non-aromatic whereas [(H(t)Pa)(3)(μ(2)-H)(6)] is anti-aromatic. However, for the thorium cluster we find a discrepancy between the current density plots and the classification through the NICS index. Our results also demonstrate the increasing influence of f orbitals, on bonding and magnetic properties, with increasing atomic number in these clusters. We think that the enhanced electron mobility in [(H(t)Pa)(3)(μ(2)-H)(6)] is due the significant 5f character of its valence shell. Also the participation of f orbitals in bonding is the reason why the protactinium cluster has the shortest bond lengths of the three clusters. This study provides another example showing that the magnetically induced current density approach can give more reliable results than the NICS index. PMID:21932909

  5. Strong enhancement of superconductivity at high pressures within the charge-density-wave states of 2 H -TaS2 and 2 H -TaSe2

    NASA Astrophysics Data System (ADS)

    Freitas, D. C.; Rodière, P.; Osorio, M. R.; Navarro-Moratalla, E.; Nemes, N. M.; Tissen, V. G.; Cario, L.; Coronado, E.; García-Hernández, M.; Vieira, S.; Núñez-Regueiro, M.; Suderow, H.

    2016-05-01

    We present measurements of the superconducting and charge-density-wave (CDW) critical temperatures (Tc and TCDW) as a function of pressure in the transition metal dichalchogenides 2 H -TaSe2 and 2 H -TaS2 . Resistance and susceptibility measurements show that Tc increases from temperatures below 1 K up to 8.5 K at 9.5 GPa in 2 H -TaS2 and 8.2 K at 23 GPa in 2 H -TaSe2 . We observe a kink in the pressure dependence of TCDW at about 4 GPa that we attribute to the lock-in transition from incommensurate CDW to commensurate CDW. Above this pressure, the commensurate TCDW slowly decreases, coexisting with superconductivity within our full pressure range.

  6. Moderate MAS enhances local 1H spin exchange and spin diffusion

    NASA Astrophysics Data System (ADS)

    Roos, Matthias; Micke, Peter; Saalwächter, Kay; Hempel, Günter

    2015-11-01

    Proton NMR spin-diffusion experiments are often combined with magic-angle spinning (MAS) to achieve higher spectral resolution of solid samples. Here we show that local proton spin diffusion can indeed become faster at low (<10 kHz) spinning rates as compared to static conditions. Spin diffusion under static conditions can thus be slower than the often referred value of 0.8 nm2/ms, which was determined using slow MAS (Clauss et al., 1993). The enhancement of spin diffusion by slow MAS relies on the modulation of the orientation-dependent dipolar couplings during sample rotation and goes along with transient level crossings in combination with dipolar truncation. The experimental finding and its explanation is supported by density matrix simulations, and also emphasizes the sensitivity of spin diffusion to the local coupling topology. The amplification of spin diffusion by slow MAS cannot be explained by any model based on independent spin pairs; at least three spins have to be considered.

  7. Understanding the symmetric line shape in the 17O MAS spectra for hexagonal ice

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuhiko; Oki, Shinobu; Deguchi, Kenzo; Shimizu, Tadashi

    2016-06-01

    Solid-state 17O Magic-Angle Spinning (MAS) nuclear magnetic resonance (NMR) spectra of 17O-enriched hexagonal ice, [17O]-Ih, between 173 and 253 K were presented. Marked changes in the line shape were clearly observed, indicating water molecular reorientation in the crystal structure. At 173 K, molecular motions were considered to be frozen and analysis of the 1D MAS spectrum yielded the following parameters: quadrupole coupling constant (CQ) = 6.6 ± 0.2 MHz and asymmetry parameter (ηQ) = 0.95 ± 0.05. At 232 K and above, contrary to the conventional explanation, pseudo-symmetric line shapes appeared in the 17O MAS NMR spectra arising from the contribution of second-order quadrupole interactions. As a chemical exchange model to describe these isotropic 17O MAS NMR spectra, a modified Ratcliffe model, which consider the effects of proton disorder, was proposed, and the resulting theoretical spectra could well reproduce the experimental spectra.

  8. Project MAS, 1982-1983. O.E.E. Evaluation Report.

    ERIC Educational Resources Information Center

    Villegas, Ana; Villegas, Jose

    This multi-site instructional program, in its first year of a three-year funding cycle, provided instruction in English as a Second Language (ESL) and native language arts, as well as bilingual instruction in various content areas, to 400 Spanish speaking students of limited English proficiency in grades 3-8. The functional goal of Project MAS,…

  9. The Multidimensional Attitudes Scale toward Persons with Disabilities (MAS): Construction and Validation

    ERIC Educational Resources Information Center

    Findler, Liora; Vilchinsky, Noa; Werner, Shirli

    2007-01-01

    This study presents the development of a new instrument, the "Multidimensional Attitudes Scale Toward Persons With Disabilities" (MAS). Based on the multidimensional approach, it posits that attitudes are composed of three dimensions: affect, cognition, and behavior. The scale was distributed to a sample of 132 people along with a self-esteem…

  10. Considerations for Consortia as States Transition Away from AA-MAS. NCEO Brief. Number 7

    ERIC Educational Resources Information Center

    National Center on Educational Outcomes, 2014

    2014-01-01

    States with an alternate assessment based on modified achievement standards (AA-MAS) that received a flexibility waiver from some of the requirements of No Child Left Behind are required to phase out their use of this assessment. And, on August 23, 2013, the U.S. Department of Education published a proposed rollback of regulation that allowed the…

  11. An Analysis of the Rise and Fall of the AA-MAS Policy

    ERIC Educational Resources Information Center

    Lazarus, Sheryl S.; Thurlow, Martha L.; Ysseldyke, James E.; Edwards, Lynn M.

    2015-01-01

    In 2005, to address concerns about students who might fall in the "gap" between the regular assessment and the alternate assessment based on alternate achievement standards (AA-AAS), the U.S. Department of Education announced that states could develop alternate assessments based on modified achievement standards (AA-MAS). This article…

  12. Successfully Transitioning from the AA-MAS to the General Assessment. NCEO Policy Directions. Number 22

    ERIC Educational Resources Information Center

    Lazarus, Sheryl; Thurlow, Martha; Christensen, Laurene; Shyyan, Vitaliy

    2014-01-01

    Federal policy initiatives such as the flexibility waivers for accountability are requiring that states transition away from the use of an alternate assessment based on modified achievement standards (AA-MAS). It is expected that those students who had participated in that assessment will instead participate in the state's general assessment…

  13. Advanced instrumentation for DNP-enhanced MAS NMR for higher magnetic fields and lower temperatures

    NASA Astrophysics Data System (ADS)

    Matsuki, Yoh; Idehara, Toshitaka; Fukazawa, Jun; Fujiwara, Toshimichi

    2016-03-01

    Sensitivity enhancement of MAS NMR using dynamic nuclear polarization (DNP) is gaining importance at moderate fields (B0 < 9 T) and temperatures (T > 90 K) with potential applications in chemistry and material sciences. However, considering the ever-increasing size and complexity of the systems to be studied, it is crucial to establish DNP under higher field conditions, where the spectral resolution and the basic NMR sensitivity tend to improve. In this perspective, we overview our recent efforts on hardware developments, specifically targeted on improving DNP MAS NMR at high fields. It includes the development of gyrotrons that enable continuous frequency tuning and rapid frequency modulation for our 395 GHz-600 MHz and 460 GHz-700 MHz DNP NMR spectrometers. The latter 700 MHz system involves two gyrotrons and a quasi-optical transmission system that combines two independent sub-millimeter waves into a single dichromic wave. We also describe two cryogenic MAS NMR probe systems operating, respectively, at T ∼100 K and ∼30 K. The latter system utilizes a novel closed-loop helium recirculation mechanism, achieving cryogenic MAS without consuming any cryogen. These instruments altogether should promote high-field DNP toward more efficient, reliable and affordable technology. Some experimental DNP results obtained with these instruments are presented.

  14. Advanced instrumentation for DNP-enhanced MAS NMR for higher magnetic fields and lower temperatures.

    PubMed

    Matsuki, Yoh; Idehara, Toshitaka; Fukazawa, Jun; Fujiwara, Toshimichi

    2016-03-01

    Sensitivity enhancement of MAS NMR using dynamic nuclear polarization (DNP) is gaining importance at moderate fields (B0<9T) and temperatures (T>90K) with potential applications in chemistry and material sciences. However, considering the ever-increasing size and complexity of the systems to be studied, it is crucial to establish DNP under higher field conditions, where the spectral resolution and the basic NMR sensitivity tend to improve. In this perspective, we overview our recent efforts on hardware developments, specifically targeted on improving DNP MAS NMR at high fields. It includes the development of gyrotrons that enable continuous frequency tuning and rapid frequency modulation for our 395 GHz-600 MHz and 460 GHz-700 MHz DNP NMR spectrometers. The latter 700 MHz system involves two gyrotrons and a quasi-optical transmission system that combines two independent sub-millimeter waves into a single dichromic wave. We also describe two cryogenic MAS NMR probe systems operating, respectively, at T ∼ 100K and ∼ 30K. The latter system utilizes a novel closed-loop helium recirculation mechanism, achieving cryogenic MAS without consuming any cryogen. These instruments altogether should promote high-field DNP toward more efficient, reliable and affordable technology. Some experimental DNP results obtained with these instruments are presented. PMID:26920836

  15. Sealed rotors for in situ high temperature high pressure MAS NMR.

    PubMed

    Hu, Jian Zhi; Hu, Mary Y; Zhao, Zhenchao; Xu, Suochang; Vjunov, Aleksei; Shi, Hui; Camaioni, Donald M; Peden, Charles H F; Lercher, Johannes A

    2015-09-11

    Here we present the design of reusable and perfectly sealed all-zirconia MAS rotors. The rotors are used to study AlPO4-5 molecular sieve crystallization under hydrothermal conditions, high temperature high pressure cyclohexanol dehydration reaction, and low temperature metabolomics of intact biological tissue. PMID:26171928

  16. Sealed Rotors for In Situ High Temperature High Pressure MAS NMR†

    PubMed Central

    Hu, Jian Zhi; Hu, Mary Y.; Zhao, Zhenchao; Xu, Suochang; Vjunov, Aleksei; Shi, Hui; Camaioni, Donald M.; Peden, Charles H. F.; Lercher, Johannes A.

    2015-01-01

    Here we present the design of reusable and perfectly-sealed all-zircornia MAS rotors. The rotors are used to study AlPO4-5 molecular sieve crystallization under hydrothermal conditions, high temperature high pressure cyclohexanol dehydration reaction, and low temperature metabolomics of intact biological tissue. PMID:26171928

  17. Genome Sequence of Streptococcus agalactiae Strain 09mas018883, Isolated from a Swedish Cow.

    PubMed

    Zubair, S; de Villiers, E P; Fuxelius, H H; Andersson, G; Johansson, K-E; Bishop, R P; Bongcam-Rudloff, E

    2013-01-01

    We announce the complete genome sequence of Streptococcus agalactiae strain 09mas018883, isolated from the milk of a cow with clinical mastitis. The availability of this genome may allow identification of candidate genes, leading to discovery of antigens that might form the basis for development of a vaccine as an alternative means of mastitis control. PMID:23846269

  18. 47 CFR 101.1317 - Competitive bidding procedures for mutually exclusive MAS EA applications.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Competitive bidding procedures for mutually exclusive MAS EA applications. 101.1317 Section 101.1317 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Multiple Address Systems...

  19. The role of isovalency in the reactions of the cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H) radicals with unsaturated hydrocarbons acetylene (C2H2) and ethylene (C2H4).

    PubMed

    Parker, D S N; Mebel, A M; Kaiser, R I

    2014-04-21

    The classification of chemical reactions based on shared characteristics is at the heart of the chemical sciences, and is well exemplified by Langmuir's concept of isovalency, in which 'two molecular entities with the same number of valence electrons have similar chemistries'. Within this account we further investigate the ramifications of the isovalency of four radicals with the same X(2)Σ(+) electronic structure - cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H), and their reactions with simple prototype hydrocarbons acetylene (C2H2) and ethylene (C2H4). The fact that these four reactants own the same X(2)Σ(+) electronic ground state should dictate the outcome of their reactions with prototypical hydrocarbons holding a carbon-carbon triple and double bond. However, we find that other factors come into play, namely, atomic radii, bonding orbital overlaps, and preferential location of the radical site. These doublet radical reactions with simple hydrocarbons play significant roles in extreme environments such as the interstellar medium and planetary atmospheres (CN, SiN and C2H), and combustion flames (C2H, BO). PMID:24418936

  20. New Cirrus Retrieval Algorithms and Results from eMAS during SEAC4RS

    NASA Astrophysics Data System (ADS)

    Holz, R.; Platnick, S. E.; Meyer, K.; Wang, C.; Wind, G.; Arnold, T.; King, M. D.; Yorks, J. E.; McGill, M. J.

    2014-12-01

    The enhanced MODIS Airborne Simulator (eMAS) scanning imager was flown on the ER-2 during the SEAC4RS field campaign. The imager provides measurements in 38 spectral channels from the visible into the 13μm CO2 absorption bands at approximately 25 m nadir spatial resolution at cirrus altitudes, and with a swath width of about 18 km, provided substantial context and synergy for other ER-2 cirrus observations. The eMAS is an update to the original MAS scanner, having new midwave and IR spectrometers coupled with the previous VNIR/SWIR spectrometers. In addition to the standard MODIS-like cloud retrieval algorithm (MOD06/MYD06 for MODIS Terra/Aqua, respectively) that provides cirrus optical thickness (COT) and effective particle radius (CER) from several channel combinations, three new algorithms were developed to take advantage of unique aspects of eMAS and/or other ER-2 observations. The first uses a combination of two solar reflectance channels within the 1.88 μm water vapor absorption band, each with significantly different single scattering albedo, allowing for simultaneous COT and CER retrievals. The advantage of this algorithm is that the strong water vapor absorption can significantly reduce the sensitivity to lower level clouds and ocean/land surface properties thus better isolating cirrus properties. A second algorithm uses a suite of infrared channels in an optimal estimation algorithm to simultaneously retrieve COT, CER, and cloud-top pressure/temperature. Finally, a window IR algorithm is used to retrieve COT in synergy with the ER-2 Cloud Physics Lidar (CPL) cloud top/base boundary measurements. Using a variety of quantifiable error sources, uncertainties for all eMAS retrievals will be shown along with comparisons with CPL COT retrievals.

  1. Fabrication and tests of 3He and 2H targets for beam polarization measurement

    PubMed

    Naqvi; Aksoy; Nagadi; Al-Ohali; Kidwai; Fageeha

    2000-09-01

    3He and 2H targets were fabricated through implantation of 3He and 2H ions in 0.2-0.3 mm thick tantalum and titanium foils. The energy of 3He and 2H ions was 45-100 and 78 keV, respectively. Ions beams with typical current of 90-300 microA were used for implantation. Stability tests of 3He and 2H targets were carried out by monitoring the yield of 3He(d, p)4He and 2H(d, p)3H reactions. For the 3He target, the reaction yield was stable for both tantalum and titanium foils but the most stabilized maximum yield was observed for the 100 keV tantalum target. In the case of 2H targets, the yield increased with increasing total dose implanted on the target. PMID:10972150

  2. Structure, phase transitions, dielectric and spectroscopic studies of the 2-aminopyrimidinium salts: [(2-NH 2C 4N 2H 3) 2H][ClO 4] and [2-NH 2C 4N 2H 4][BF 4

    NASA Astrophysics Data System (ADS)

    Czupiński, O.; Wojtaś, M.; Ciunik, Z.; Jakubas, R.

    2006-01-01

    Crystal structure of the 2-aminopyrimidinium derivatives: [(2-NH 2C 4N 2H 3) 2H][ClO 4] (I) and [2-NH 2C 4N 2H 4][BF 4] (II) has been determined at 100 K (I) and 293 K (II) by means of single crystal X-ray diffraction as monoclinic space group, P2/c and P2/n, respectively. The asymmetric part of the unit cell of (I) contains two symmetry independent 2-aminopyrimidine forming one dimeric cation and one disordered perchlorate anion. The structure of (II) consists of 2-aminopyrimidinium cation, [2-NH 2C 4N 2H 4] +, protonated at a pyrimidine ring-N atom and [BF 4] - anion. Differential scanning calorimetry (DSC) on perchlorate derivative ( 1:1), [2-NH 2C 4N 2H 3][ClO 4] (III)—being isomorphic to tetrafluoroborate one (I) at room temperature, reveals two phase transitions of first order: at 250/275 K and 390/410 K (cooling-heating, respectively), whereas the analog (II) only one transition at high temperatures—343/385 K. The dielectric studies in the frequency range 75 kHz - 10 MHz disclose relaxation process at high temperatures in salt (I). Infrared spectra of polycrystalline [2-NH 2C 4N 2H 4][BF 4] have been studied in the temperature range 300-420 K. Substantial changes in the temperature evolution of frequencies of internal modes of the 2-aminopyrimidinium cations and [BF 4] - anions near 390 K are due to the variations in the motion of both moieties and hydrogen bond configuration. The experimental studies indicate that all phase transitions taking place in studied 2-aminopyrimidinium derivatives are classified as an order-disorder.

  3. Crystal structure, NMR study, dc-conductivity and dielectric relaxation studies of a new compound [C2H10N2]Cd(SCN)2Cl2

    NASA Astrophysics Data System (ADS)

    Saidi, K.; Kamoun, S.; Ayedi, H. F.; Gargouri, M.

    2012-06-01

    The crystal structure, the solid NMR spectroscopy and the complex impedance study have been carried out on [C2H10N2]CdCl2(SCN)2. Characterization by single crystal X-ray crystallography shows that the cadmium atoms have à 2N2S2Cl hexa-coordination sphere, exhibiting pseudo-octahedral geometry. The cadmium atoms are bridged by two thiocyanate ions generating 1-D polymeric-chains. These chains are themselves interconnected by means of N-H…Cl(NCS) hydrogen bonds originating from the organic cation [(NH3)2(CH2)2]2+. 111Cd isotropic chemical shifts span a range of 268ppm. The cadmium atom exhibits multiplets that result from 111Cd-14N spin-spin coupling. Examination of 111Cd and 13C MAS line shapes shows direct measurement of the indirect spin-spin coupling constant 2J(111Cd, 14N) = 105Hz and the dipolar coupling constant of 1381Hz . Impedance spectroscopy measurements of [C2H10N2]CdCl2(SCN)2 have been studied from 209Hz to 5 MHz over the temperature range 300-370 K. The Cole-Cole (Z" versus Z') plots are fitted to two equivalent circuits models. The formalism of complex permittivity and impedance were employed to analyze the experimental data. The dc conductivity follows the Arrhenius relation with an activation energy Ea = 0.54 (3) eV.

  4. 2H NMR study of phase transition and hydrogen dynamics in hydrogen bonded organic antiferroelectric 55DMBP-H2ca

    NASA Astrophysics Data System (ADS)

    Asaji, Tetsuo; Hara, Masamichi; Fujimori, Hiroki; Hagiwara, Shoko

    2016-12-01

    Hydrogen dynamics in one-dimensional hydrogen bonded organic antiferroelectric, co-crystal of 5,5'-dimethyl-2,2'-bipyridine (55DMBP) and chloranilic acid (H2ca), was investigated by use of 2H high resolution solid-state NMR. The two types of hydrogen bonds O-H …N and N+-H … O - in the antiferroelectric phase were clearly observed as the splitting of the side band of the 2H MAS NMR spectra of the acid-proton deuterated compound 55DMBP-D 2ca. The temperature dependence of the spin-lattice relaxation time was measured of the N+-H and O-H deuterons, respectively. It was suggested that the motion of the O-H deuteron is already in the antiferroelectric phase in the fast-motion regime in the NMR time scale, while that of the N+-H deuteron is a slow motion. In the high-temperature paraelectric phase, the both deuterons become equivalent and the fast motion of the deuterons in the NMR time scale is taking place with the activation energy of 7.9 kJ mol-1.

  5. The SNF2H Chromatin Remodeling Enzyme Has Opposing Effects on Cytokine Gene Expression

    PubMed Central

    Precht, Patricia; Wurster, Andrea L.; Pazin, Michael J.

    2010-01-01

    Cytokine gene expression is a key control point in the function of the immune system. Cytokine gene regulation is linked to changes in chromatin structure; however, little is known about the remodeling enzymes mediating these changes. Here we investigated the role of the ATP-dependent chromatin remodeling enzyme SNF2H in mouse T cells; to date, SNF2H has not been investigated in T cells. We found that SNF2H repressed expression of IL-2 and other cytokines in activated cells. By contrast, SNF2H activated expression of IL-3. The ISWI components SNF2H and ACF1 bound to the tested loci, suggesting the regulation was direct. SNF2H decreased accessibility at some binding sites within the IL2 locus, and increased accessibility within some IL3 binding sites. The changes in gene expression positively correlated with accessibility changes, suggesting a simple model that accessibility enables transcription. We also found that loss of the ISWI ATPase SNF2H reduced binding to target genes and protein expression of ACF1, a binding partner for SNF2H, suggesting complex formation stabilized ACF1. Together, these findings reveal a direct role for SNF2H in both repression and activation of cytokine genes. PMID:20471682

  6. Chemical behavior of the gas-phase pentacoordinated carbonium ion, C2H+7

    NASA Astrophysics Data System (ADS)

    Heck, Albert J. R.; de Koning, Leo J.; Nibbering, Nico M. M.

    1992-09-01

    The uni- and bimolecular chemistry of C2H+7 ions have been studied in the gas phase using the methods of sector and Fourier transform ion cyclotron resonance mass spectrometry. Unimolecular decomposition of the C2H+7 ions predominantly shows the elimination of a hydrogen molecule which proceeds without a significant kinetic energy release. However, the elimination of a hydrogen molecule is found to suffer from a very large isotope effect, which has been rationalized by the difference in Gibbs free energy change for H2, HD and D2 loss from the various isotopomers of protonated ethane. In general, long-lived C2H+7 ions can be generated either by proton transfer to ethane, methyl cation transfer to methane or by association of C2H+5 and H2. Conversely, C2H+7 ions can react as a proton or a methyl cation donor, or eliminate an H2 molecule. In contrast to CH+5, C2H+7 displays an ambident chemical behavior, which shows a balanced competition between a proton and a methyl cation donor. Both the uni- and bimolecular reactivity of C2H+7 reveal that the proton accepted in an exothermic protonation of ethane randomizes with the original hydrogen atoms of ethane. This intramolecular randomization is found to be a very fast process which precedes decomposition of the metastable C2H+7 ions as well as the bimolecular processes of the long-lived C2H+7 ions.

  7. SNF2H promotes hepatocellular carcinoma proliferation by activating the Wnt/β-catenin signaling pathway

    PubMed Central

    Wang, Yanan; Qin, Juanxiu; Liu, Qian; Hong, Xufen; Li, Tianming; Zhu, Yuanjun; He, Lei; Zheng, Bing; Li, Min

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and has an extremely poor prognosis. Surgical resection is always inapplicable to HCC patients diagnosed at an advanced tumor stage. The mechanisms underlying HCC cell proliferation remain obscure. In the present study, SWItch/sucrose nonfermentable catalytic subunit SNF2 (SNF2H) expression was tested in HCC tissues and Wnt/β-catenin pathway activation upon overexpression of SNF2H or knockdown of SNF2H expression was investigated in cultured HCC cells. It was demonstrated that SNF2H is a vital factor for HCC growth. The SNF2H expression level is increased in HCC tissues compared with paratumoral liver tissues. SNF2H promotes HCC cell proliferation and colony formation ability in vitro. SNF2H may increase the protein level of β-catenin and enhance its nuclear accumulation in HCC cells, thereby leading to the activation of the Wnt/β-catenin signaling pathway. In conclusion, the present results indicate that SNF2H plays a vital role in HCC cell growth, suggesting that SNF2H may be a promising therapeutic target for HCC treatment. PMID:27446433

  8. Hyperspectral Microwave Atmospheric Sounder (HyMAS) Architecture and Design Accommodations

    NASA Technical Reports Server (NTRS)

    Hilliard, Lawrence; Racette, Paul; Blackwell, William; Galbraith, Christopher; Thompson, Erik

    2013-01-01

    The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term "hyperspectral microwave" is used to indicate an all-weather sounding that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earth s atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions. The simulations proposed for HyMAS 118/183-GHz system should yield surface precipitation rate and water path retrievals for small hail, soft hail, or snow pellets, snow, rainwater, etc. with accuracies comparable to those of the Advanced Technology Microwave Sounder. Further improvements in retrieval methodology (for example, polarization exploitation) are expected. The CoSMIR instrument is a packaging concept re-used on HyMAS to ease the integration features of the scanhead. The HyMAS scanhead will include an ultra-compact Intermediate Frequency Processor (IFP) module that is mounted inside the door to improve thermal management. The IFP is fabricated with materials made of Low-Temperature Co-fired Ceramic (LTCC) technology integrated with detectors, amplifiers, A/D conversion and data aggregation. The IFP will put out 52 channels of 16 bit data comprised of 4-9 channel data streams for temperature profiles and 2-8 channel streams for water vapor. With the limited volume of the existing CoSMIR scanhead and new HyMAS front end components, the HyMAS team at Goddard began preliminary layout work inside the new drum. Importing and re-using models of the shell, the scan head computer

  9. Hyperspectral Microwave Atmospheric Sounder (HyMAS) architecture and design accommodations

    NASA Astrophysics Data System (ADS)

    Hilliard, L.; Racette, P.; Blackwell, W.; Galbraith, C.; Thompson, E.

    The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term “ hyperspectral microwave” is used to indicate an all-weather sounding that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earth's atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions. The simulations proposed for HyMAS 118/183-GHz system should yield surface precipitation rate and water path retrievals for small hail, soft hail, or snow pellets, snow, rainwater, etc. with accuracies comparable to those of the Advanced Technology Microwave Sounder. Further improvements in retrieval methodology (for example, polarization exploitation) are expected. The CoSMIR instrument is a packaging concept re-used on HyMAS to ease the integration features of the scanhead. The HyMAS scanhead will include an ultra-compact Intermediate Frequency Processor (IFP) module that is mounted inside the door to improve thermal management. The IFP is fabricated with materials made of Low-Temperature Co-fired Ceramic (LTCC) technology integrated with detectors, amplifiers, A/D conversion and data aggregation. The IFP will put out 52 channels of 16 bit data comprised of 4 - 9 channel data streams for temperature profiles and 2-8 channel streams for water vapor. With the limited volume of the existing CoSMIR scanhead and new HyMAS front end components, the HyMAS team at Goddard began preliminary layout work inside the new drum. Importing and re-using models of the shell, the s- an head

  10. States' Participation Guidelines for Alternate Assessments Based on Modified Academic Achievement Standards (AA-MAS) in 2009. Synthesis Report 75

    ERIC Educational Resources Information Center

    Lazarus, Sheryl S.; Hodgson, Jennifer; Thurlow, Martha L.

    2010-01-01

    All students, including students with disabilities, must be included in state accountability systems as required by law. In April 2007, federal regulations provided states the flexibility to offer another assessment option--an Alternate Assessment based on Modified Achievement Standards (AA-MAS) for some students with disabilities. The AA-MAS is…

  11. Participation and Performance Reporting for the Alternate Assessment Based on Modified Achievement Standards (AA-MAS). Technical Report 58

    ERIC Educational Resources Information Center

    Albus, Deb; Thurlow, Martha L.; Lazarus, Sheryl S.

    2011-01-01

    This report examines publicly reported participation and performance data for the alternate assessment based on modified achievement standards (AA-MAS). The authors' analysis of these data included all states publicly reporting AA-MAS data, regardless of whether they had received approval to use the results for Title I accountability calculations.…

  12. Comparison of the 1H NMR analysis of solids by the CRAMPS and MAS-only techniques

    NASA Astrophysics Data System (ADS)

    Dec, Steven F.; Bronnimann, Charles E.; Wind, Robert A.; Maciel, Gary E.

    1H NMR spectra are reported on eight representative solid samples, including pure powdered crystalline samples, synthetic organic polymers, a silica gel, HY zeolite, and a lignite. Spectra were obtained by the following three approaches: (1) single pulse on a static sample, (2) CRAMPS, and (3) single pulse with magic-angle spinning (MAS-only). The MAS-only results were obtained as a function of MAS speed. Although the MAS-only technique is capable of achieving a significant degree of line narrowing, even with modest MAS speeds, MAS-only spectra of the general quality of the apparently undistorted high-resolution 1H spectra obtained by the CRAMPS technique are not obtained at the highest MAS speeds examined (21 kHz for a polymethylmethacrylate sample), unless the 1H- 1H dipolar interactions in the sample are rather weak, as with silica gel or a zeolite. Thus, caution should be exercised in interpreting 1H MAS-only spectra, especially if CRAMPS results are not available as a calibration.

  13. Heteromerization Between the Bradykinin B2 Receptor and the Angiotensin-(1-7) Mas Receptor: Functional Consequences.

    PubMed

    Cerrato, Bruno D; Carretero, Oscar A; Janic, Brana; Grecco, Hernán E; Gironacci, Mariela M

    2016-10-01

    Bradykinin B2 receptor (B2R) and angiotensin-(1-7) Mas receptor (MasR)-mediated effects are physiologically interconnected. The molecular basis for such cross talk is unknown. It is hypothesized that the cross talk occurs at the receptor level. We investigated B2R-MasR heteromerization and the functional consequences of such interaction. B2R fused to the cyan fluorescent protein and MasR fused to the yellow fluorescent protein were transiently coexpressed in human embryonic kidney293T cells. Fluorescence resonance energy transfer analysis showed that B2R and MasR formed a constitutive heteromer, which was not modified by their agonists. B2R or MasR antagonists decreased fluorescence resonance energy transfer efficiency, suggesting that the antagonist promoted heteromer dissociation. B2R-MasR heteromerization induced an 8-fold increase in the MasR ligand-binding affinity. On agonist stimulation, the heteromer was internalized into early endosomes with a slower sequestration rate from the plasma membrane, compared with single receptors. B2R-MasR heteromerization induced a greater increase in arachidonic acid release and extracellular signal-regulated kinase phosphorylation after angiotensin-(1-7) stimulation, and this effect was blocked by the B2R antagonist. Concerning serine/threonine kinase Akt activity, a significant bradykinin-promoted activation was detected in B2R-MasR but not in B2R-expressing cells. Angiotensin-(1-7) and bradykinin elicited antiproliferative effects only in cells expressing B2R-MasR heteromers, but not in cells expressing each receptor alone. Proximity ligation assay confirmed B2R-MasR interaction in human glomerular endothelial cells supporting the interaction between both receptors in vivo. Our findings provide an explanation for the cross talk between bradykinin B2R and angiotensin-(1-7) MasR-mediated effects. B2R-MasR heteromerization induces functional changes in the receptor that may lead to long-lasting protective properties. PMID

  14. Calculational and Experimental Investigations of the Pressure Effects on Radical - Radical Cross Combinations Reactions: C2H5 + C2H3

    NASA Technical Reports Server (NTRS)

    Fahr, Askar; Halpern, Joshua B.; Tardy, Dwight C.

    2007-01-01

    Pressure-dependent product yields have been experimentally determined for the cross-radical reaction C2H5 + C2H3. These results have been extended by calculations. It is shown that the chemically activated combination adduct, 1-C4H8*, is either stabilized by bimolecular collisions or subject to a variety of unimolecular reactions including cyclizations and decompositions. Therefore the "apparent" combination/disproportionation ratio exhibits a complex pressure dependence. The experimental studies were performed at 298 K and at selected pressures between about 4 Torr (0.5 kPa) and 760 Torr (101 kPa). Ethyl and vinyl radicals were simultaneously produced by 193 nm excimer laser photolysis of C2H5COC2H3 or photolysis of C2H3Br and C2H5COC2H5. Gas chromatograph/mass spectrometry/flame ionization detection (GC/MS/FID) were used to identify and quantify the final reaction products. The major combination reactions at pressures between 500 (66.5 kPa) and 760 Torr are (1c) C2H5 + C2H3 yields 1-butene, (2c) C2H5 + C2H5 yields n-butane, and (3c) C2H3 + C2H3 yields 1,3-butadiene. The major products of the disproportionation reactions are ethane, ethylene, and acetylene. At moderate and lower pressures, secondary products, including propene, propane, isobutene, 2-butene (cis and trans), 1-pentene, 1,4-pentadiene, and 1,5-hexadiene are also observed. Two isomers of C4H6, cyclobutene and/or 1,2-butadiene, were also among the likely products. The pressure-dependent yield of the cross-combination product, 1-butene, was compared to the yield of n-butane, the combination product of reaction (2c), which was found to be independent of pressure over the range of this study. The [ 1-C4H8]/[C4H10] ratio was reduced from approx.1.2 at 760 Torr (101 kPa) to approx.0.5 at 100 Torr (13.3 kPa) and approx.0.1 at pressures lower than about 5 Torr (approx.0.7 kPa). Electronic structure and RRKM calculations were used to simulate both unimolecular and bimolecular processes. The relative importance

  15. Angiotensin-(1-7) attenuates disuse skeletal muscle atrophy in mice via its receptor, Mas

    PubMed Central

    Morales, María Gabriela; Abrigo, Johanna; Acuña, María José; Santos, Robson A.; Bader, Michael; Brandan, Enrique; Simon, Felipe; Olguin, Hugo; Cabrera, Daniel; Cabello-Verrugio, Claudio

    2016-01-01

    ABSTRACT Immobilization is a form of disuse characterized by a loss of strength and muscle mass. Among the main features are decreased IGF-1/Akt signalling and increased ubiquitin-proteasome pathway signalling, which induce greater myosin heavy chain degradation. Activation of the classical renin-angiotensin system (RAS) causes deleterious effects in skeletal muscle, including muscle wasting. In contrast, angiotensin-(1-7) [Ang-(1-7)], a peptide of the non-classical RAS, produces beneficial effects in skeletal muscle. However, the role of Ang-(1-7) in skeletal muscle disuse atrophy and independent of classical RAS activation has not been evaluated. Therefore, we assessed the functions of Ang-(1-7) and the Mas receptor in disuse muscle atrophy in vivo using unilateral cast immobilization of the hind limb in male, 12-week-old wild-type (WT) and Mas-knockout (Mas KO) mice for 1 and 14 days. Additionally, we evaluated the participation of IGF-1/IGFR-1/Akt signalling and ubiquitin-proteasome pathway expression on the effects of Ang-(1-7) immobilization-induced muscle atrophy. Our results found that Ang-(1-7) prevented decreased muscle strength and reduced myofiber diameter, myosin heavy chain levels, and the induction of atrogin-1 and MuRF-1 expressions, all of which normally occur during immobilization. Analyses indicated that Ang-(1-7) increases IGF-1/IGFR-1/Akt pathway signalling through IGFR-1 and Akt phosphorylation, and the concomitant activation of two downstream targets of Akt, p70S6K and FoxO3. These anti-atrophic effects of Ang-(1-7) were not observed in Mas KO mice, indicating crucial participation of the Mas receptor. This report is the first to propose anti-atrophic effects of Ang-(1-7) via the Mas receptor and the participation of the IGF-1/IGFR-1/Akt/p70S6K/FoxO3 mechanism in disuse skeletal muscle atrophy. PMID:26851244

  16. Semi-parametric time-domain quantification of HR-MAS data from prostate tissue

    PubMed Central

    Ratiney, Helene; Albers, Mark J.; Rabeson, Herald; Kurhanewicz, John

    2011-01-01

    High Resolution – Magic Angle Spinning (HR-MAS) spectroscopy provides rich biochemical profiles that require accurate quantification to permit biomarker identification and to understand the underlying pathological mechanisms. Meanwhile, quantification of HR-MAS data from prostate tissue samples is challenging due to significant overlap between the resonant peaks, the presence of short T2∗ metabolites such as citrate or polyamines (T2 from 25 to 100 msec) and macromolecules, and variations in chemical shifts and T2∗s within a metabolite’s spin systems. Since existing methods do not address these challenges completely, a new quantification method was developed and optimized for HR-MAS data acquired with an ultra short TE and over 30,000 data points. The proposed method, named HR-QUEST (High Resolution – QUEST), iteratively employs the QUEST time-domain semi-parametric strategy with a new model function that incorporates prior knowledge from whole and subdivided metabolite signals. With these features, HR-QUEST is able to independently fit the chemical shifts and T2∗s of a metabolite’s spin systems, a necessity for HR-MAS data. By using the iterative fitting approach, it is able to account for significant contributions from macromolecules and to handle shorter T2 metabolites, such as citrate and polyamines. After subdividing the necessary metabolite basis signals, the root mean square (RMS) of the residual was reduced by 52% for measured HR-MAS data from prostate tissue. Monte Carlo studies on simulated spectra with varied macromolecular contributions showed that the iterative fitting approach (6 iterations) coupled with inclusion of long T2 macromolecule components in the basis set improve the quality of the fit, as assessed by the reduction of the RMS of the residual and of the RMS error of the metabolite signal estimate, by 27% and 71% respectively. With this optimized configuration, HR-QUEST was applied to measured HR-MAS prostate data and reliably

  17. Angiotensin-(1-7) attenuates disuse skeletal muscle atrophy in mice via its receptor, Mas.

    PubMed

    Morales, María Gabriela; Abrigo, Johanna; Acuña, María José; Santos, Robson A; Bader, Michael; Brandan, Enrique; Simon, Felipe; Olguin, Hugo; Cabrera, Daniel; Cabello-Verrugio, Claudio

    2016-04-01

    Immobilization is a form of disuse characterized by a loss of strength and muscle mass. Among the main features are decreased IGF-1/Akt signalling and increased ubiquitin-proteasome pathway signalling, which induce greater myosin heavy chain degradation. Activation of the classical renin-angiotensin system (RAS) causes deleterious effects in skeletal muscle, including muscle wasting. In contrast, angiotensin-(1-7) [Ang-(1-7)], a peptide of the non-classical RAS, produces beneficial effects in skeletal muscle. However, the role of Ang-(1-7) in skeletal muscle disuse atrophy and independent of classical RAS activation has not been evaluated. Therefore, we assessed the functions of Ang-(1-7) and the Mas receptor in disuse muscle atrophyin vivousing unilateral cast immobilization of the hind limb in male, 12-week-old wild-type (WT) and Mas-knockout (Mas KO) mice for 1 and 14 days. Additionally, we evaluated the participation of IGF-1/IGFR-1/Akt signalling and ubiquitin-proteasome pathway expression on the effects of Ang-(1-7) immobilization-induced muscle atrophy. Our results found that Ang-(1-7) prevented decreased muscle strength and reduced myofiber diameter, myosin heavy chain levels, and the induction of atrogin-1 and MuRF-1 expressions, all of which normally occur during immobilization. Analyses indicated that Ang-(1-7) increases IGF-1/IGFR-1/Akt pathway signalling through IGFR-1 and Akt phosphorylation, and the concomitant activation of two downstream targets of Akt, p70S6K and FoxO3. These anti-atrophic effects of Ang-(1-7) were not observed in Mas KO mice, indicating crucial participation of the Mas receptor. This report is the first to propose anti-atrophic effects of Ang-(1-7) via the Mas receptor and the participation of the IGF-1/IGFR-1/Akt/p70S6K/FoxO3 mechanism in disuse skeletal muscle atrophy. PMID:26851244

  18. 77 FR 74283 - Clearing Requirement Determination Under Section 2(h) of the CEA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ...\\ Clearing Requirement Determination Under Section 2(h) of the CEA; Proposed Rule, 77 FR 47170 (Aug. 7, 2012... to Trade Under Section 2(h)(8) of the Commodity Exchange Act, 76 FR 77728 (Dec. 14, 2011). Clearing... FR 44464 (July 26, 2011); 17 CFR 39.5. The determinations and rules adopted in this release...

  19. Technology Development for a Hyperspectral Microwave Atmospheric Sounder (HyMAS)

    NASA Technical Reports Server (NTRS)

    Blackwell, W.; Galbraith, C.; Hilliard, L.; Racette, P.; Thompson, E.

    2014-01-01

    The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term hyperspectral microwave is used to indicate an all-weather sounding instrument that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earths atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions.

  20. Decomposition of adsorbed VX on activated carbons studied by {sup 31}P MAS NMR

    SciTech Connect

    Ishay Columbus; Daniel Waysbort; Liora Shmueli; Ido Nir; Doron Kaplan

    2006-06-15

    The fate of the persistent OP nerve agent O-ethyl S-(2-(diisopropylamino)ethyl) methylphosphonothioate (VX) on granular activated carbons that are used for gas filtration was studied by means of 31P magic angle spinning (MAS) NMR spectroscopy. Four types of activated carbon were used, including coal-based BPL. VX as vapor or liquid was adsorbed on carbon granules, and MAS NMR spectra were recorded periodically. The results show that at least 90% of the adsorbed VX decomposes within 20 days or less to the nontoxic ethyl methylphosphonic acid (EMPA) and bis(S-2-diisopropylaminoethane) ((DES){sub 2}). Decomposition occurred irrespective of the phase from which VX was loaded, the presence of metal impregnation on the carbon surface, and the water content of the carbon. Theoretical and practical aspects of the degradation are discussed. 17 refs., 6 figs., 3 tabs.

  1. Decomposition of adsorbed VX on activated carbons studied by 31P MAS NMR.

    PubMed

    Columbus, Ishay; Waysbort, Daniel; Shmueli, Liora; Nir, Ido; Kaplan, Doron

    2006-06-15

    The fate of the persistent OP nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) on granular activated carbons that are used for gas filtration was studied by means of 31P magic angle spinning (MAS) NMR spectroscopy. VX as vapor or liquid was adsorbed on carbon granules, and MAS NMR spectra were recorded periodically. The results show that at least 90% of the adsorbed VX decomposes within 20 days or less to the nontoxic ethyl methylphosphonic acid (EMPA) and bis(S-2-diisopropylaminoethane) {(DES)2}. Decomposition occurred irrespective of the phase from which VX was loaded, the presence of metal impregnation on the carbon surface, and the water content of the carbon. Theoretical and practical aspects of the degradation are discussed. PMID:16830567

  2. El Proyecto Sismico "LARSE" - Trabajando Hacia un Futuro con Mas Seguridad para Los Angeles

    USGS Publications Warehouse

    Henyey, Thomas L.; Fuis, Gary S.; Benthien, Mark L.; Burdette, Thomas R.; Christofferson, Shari A.; Clayton, Robert W.; Criley, Edward E.; Davis, Paul M.; Hendley, James W., II; Kohler, Monica D.; Lutter, William J.; McRaney, John K.; Murphy, Janice M.; Okaya, David A.; Ryberg, Trond; Simila, Gerald W.; Stauffer, Peter H.

    1999-01-01

    La region de Los Angeles contiene una red de fallas activas, incluyendo muchas fallas por empuje que son profundas y no rompen la superficie de la tierra. Estas fallas ocultas incluyen la falla anteriormente desconocida que fue responsable por la devastacion que ocurrio durante el terremoto de Northridge en enero de 1994, el terremoto mas costoso en la historia de los Estados Unidos. El Experimento Sismico en la Region de Los Angeles (Los Angeles Region Seismic Experiment, LARSE), esta localizando los peligros ocultos de los terremotos debajo de la region de Los Angeles para mejorar la construccion de las estructuras que pueden apoyar terremotos que son inevitables en el futuro, y que ayudaran a los cientificos determinar donde occurira el sacudimento mas fuerte y poderoso.

  3. MICROWAVE SPECTRA AND GEOMETRIES OF C2H_{2\\cdots AgI} and C2H_{4\\cdots AgI}

    NASA Astrophysics Data System (ADS)

    Stephens, Susanna L.; Tew, David Peter; Walker, Nick; Legon, Anthony

    2015-06-01

    A chirped-pulse Fourier transform microwave spectrometer has been used to measure the microwave spectra of both C2H_{2\\cdots AgI} and C2H_{4\\cdots AgI}. These complexes are generated via laser ablation at 532 nm of a silver surface in the presence of CF3I and either C2H_{2} or C2H_{4} and argon and are stabilized by a supersonic expansion. Rotational (A0, B0, C0) and centrifugal distortion constants (ΔJ and ΔJK) of each molecule have been determined as well the nuclear electric quadrupole coupling constants the iodine atom (χaa(I) and χbb-χcc(I)). The spectrum of each molecule is consistent with a C2v structure in which the metal atom interacts with the π-orbital of the ethene or ethyne molecule. Isotopic substitutions of atoms within the C2H_{2} or C2H_{4} subunits are in progress and in conjunction with high level ab initio calculations will allow for accurate determination of the geometry of each molecule. These to complexes are put in the context of the recently studied H2S\\cdots AgI, OC\\cdotsAgI, H3N\\cdots AgI and (CH3)_{3N\\cdots AgI}. S.Z. Riaz, S.L. Stephens, W. Mizukami, D.P. Tew, N.R. Walker, A.C. Legon, Chem. Phys. Let., 531, 1-12 (2012) S.L. Stephens, W. Mizukami, D.P. Tew, N.R. Walker, A.C. Legon, J. Chem. Phys., 136(6), 064306 (2012) D.M. Bittner, D.P. Zaleski, S.L. Stephens, N.R. Walker, A.C. Legon, Study in progress.

  4. Highly efficient Agrobacterium-mediated transformation of embryogenic cell suspensions of Musa acuminata cv. Mas (AA) via a liquid co-cultivation system.

    PubMed

    Huang, Xia; Huang, Xue-Lin; Xiao, Wang; Zhao, Jie-Tang; Dai, Xue-Mei; Chen, Yun-Feng; Li, Xiao-Ju

    2007-10-01

    A high efficient protocol of Agrobacterium-mediated transformation of Musa acuminata cv. Mas (AA), a major banana variety of the South East Asia region, was developed in this study. Male-flower-derived embryogenic cell suspensions (ECS) were co-cultivated in liquid medium with Agrobacterium strain EHA105 harboring a binary vector pCAMBIA2301 carrying nptII and gusA gene in the T-DNA. Depending upon conditions and duration of co-cultivation in liquid medium, 0-490 transgenic plants per 0.5 ml packed cell volume (PCV) of ECS were obtained. The optimum duration of inoculation was 2 h, and the highest transformation frequency was achieved when infected ECS were co-cultivated in liquid medium first for 12 h at 40 rpm and then for 156 h at 100 rpm on a rotary shaker. Co-cultivation for a shorter duration (72 h) or shaking constantly at 100 rpm at the same duration gave 1.6 and 1.8 folds lower transformation efficiency, respectively. No transgenic plants were obtained in parallel experiments carried on semi-solid media. Histochemical GUS assay and molecular analysis in several tissues of the transgenic plants demonstrated that foreign genes were stably integrated into the banana genome. Compared to semi-solid co-cultivation transformation in other banana species, it is remarkable that liquid co-cultivation was much more efficient for transformation of the Mas cultivar, and was at least 1 month faster for regenerating transgenic plants. PMID:17551731

  5. The transcriptional regulator c2h2 accelerates mushroom formation in Agaricus bisporus.

    PubMed

    Pelkmans, Jordi F; Vos, Aurin M; Scholtmeijer, Karin; Hendrix, Ed; Baars, Johan J P; Gehrmann, Thies; Reinders, Marcel J T; Lugones, Luis G; Wösten, Han A B

    2016-08-01

    The Cys2His2 zinc finger protein gene c2h2 of Schizophyllum commune is involved in mushroom formation. Its inactivation results in a strain that is arrested at the stage of aggregate formation. In this study, the c2h2 orthologue of Agaricus bisporus was over-expressed in this white button mushroom forming basidiomycete using Agrobacterium-mediated transformation. Morphology, cap expansion rate, and total number and biomass of mushrooms were not affected by over-expression of c2h2. However, yield per day of the c2h2 over-expression strains peaked 1 day earlier. These data and expression analysis indicate that C2H2 impacts timing of mushroom formation at an early stage of development, making its encoding gene a target for breeding of commercial mushroom strains. PMID:27207144

  6. Bi(OTf)3-catalyzed addition of isocyanides to 2H-chromene acetals: an efficient pathway for accessing 2-carboxamide-2H-chromenes.

    PubMed

    Lyu, Longyun; Jin, Ming Yu; He, Qijie; Xie, Han; Bian, Zhaoxiang; Wang, Jun

    2016-09-14

    Bismuth triflate (Bi(OTf)3) is identified as an efficient catalyst for the direct addition of isocyanides to 2H-chromene acetals. The large scope of isocyanides and chromene acetals makes them suitable substrates in this catalytic system. By this synthetic strategy, a polyfunctional molecular scaffold, 2-carboxamide-2H-chromenes could be prepared efficiently in one step up to 95% yield. In addition, this efficient and practical protocol proceeded smoothly in the gram scale even when the catalytic loading was reduced to 2 mol%. PMID:27503764

  7. ACE2, angiotensin-(1-7) and Mas receptor axis in inflammation and fibrosis

    PubMed Central

    Simões e Silva, AC; Silveira, KD; Ferreira, AJ; Teixeira, MM

    2013-01-01

    Recent advances have improved our understanding of the renin-angiotensin system (RAS). These have included the recognition that angiotensin (Ang)-(1-7) is a biologically active product of the RAS cascade. The identification of the ACE homologue ACE2, which forms Ang-(1-7) from Ang II, and the GPCR Mas as an Ang-(1-7) receptor have provided the necessary biochemical and molecular background and tools to study the biological significance of Ang-(1-7). Most available evidence supports a counter-regulatory role for Ang-(1-7) by opposing many actions of Ang II on AT1 receptors, especially vasoconstriction and proliferation. Many studies have now shown that Ang-(1-7) by acting via Mas receptor exerts inhibitory effects on inflammation and on vascular and cellular growth mechanisms. Ang-(1-7) has also been shown to reduce key signalling pathways and molecules thought to be relevant for fibrogenesis. Here, we review recent findings related to the function of the ACE2/Ang-(1-7)/Mas axis and focus on the role of this axis in modifying processes associated with acute and chronic inflammation, including leukocyte influx, fibrogenesis and proliferation of certain cell types. More attention will be given to the involvement of the ACE2/Ang-(1-7)/Mas axis in the context of renal disease because of the known relevance of the RAS for the function of this organ and for the regulation of kidney inflammation and fibrosis. Taken together, this knowledge may help in paving the way for the development of novel treatments for chronic inflammatory and renal diseases. PMID:23488800

  8. Tetrahedral site ordering in synthetic gallium albite: A 29Si MAS NMR study

    NASA Astrophysics Data System (ADS)

    Sherriff, Barbara L.; Fleet, Michael E.; Burns, Peter C.

    1991-09-01

    The ordering of Si in the tetrahedral sites of gallium albite (NaGaSi 3O 8) has been studied by MAS NMR and Rietveld structure refinement of X-ray powder diffraction data. Low structural state (ordered) material was annealed at about 800°C under a load pressure of 1 kbar, and by Rietveld refinement has tetrahedral-site occupancies for Si of T1O = 0.24(3), T1m = 0.89(2), T2O = 0.98(2), and T2m = 0.89(2), respectively. Corresponding Si occupancies for high structural state (disordered) material are 0.71(2), 0.78(1), 0.76(2), and 0.74(2), respectively. The 29Si MAS NMR spectra of low gallium albite is equivalent to the three-peak spectrum of natural (Amelia) albite, with resonances at -89.6, -96.4, and -104.2 ppm but with relative peak areas of 0.79:1.0:0.77. The tetrahedral-site occupancies derived from the MAS NMR spectrum are in good agreement with those obtained by Rietveld refinement and, in particular, indicate that the -96.4 ppm peak must correspond to Si in T2O. This is the first independent assignment of the 29Si peak at -96 ppm in the spectrum of ordered albite to the T2O site. A peak at -96 ppm is also resolved in the spectrum of high gallium albite. The systematic differences in peak position between the 29Si MAS NMR spectra of low gallium albite and those of Amelia albite cannot be explained simply by the direct replacement of Al by Ga, without a change in angle at the bridging oxygen atoms.

  9. Hydrogen bridging in the compounds X2H (X=Al,Si,P,S)

    NASA Astrophysics Data System (ADS)

    Owens, Zachary T.; Larkin, Joseph D.; Schaefer, Henry F.

    2006-10-01

    X2H hydrides (X =Al, Si, P, and S) have been investigated using coupled cluster theory with single, double, and triple excitations, the latter incorporated as a perturbative correction [CCSD(T)]. These were performed utilizing a series of correlation-consistent basis sets augmented with diffuse functions (aug-cc-pVXZ, X =D, T, and Q). Al2H and Si2H are determined to have H-bridged C2v structures in their ground states: the Al2H ground state is of B12 symmetry with an Al-H-Al angle of 87.6°, and the Si2H ground state is of A12 symmetry with a Si-H-Si angle of 79.8°. However, P2H and S2H have nonbridged, bent Cs structures: the P2H ground state is of A'2 symmetry with a P-P-H angle of 97.0°, and the S2H ground state is of A'2 symmetry with a S-S-H angle of 93.2°. Ground state geometries, vibrational frequencies, and electron affinities have been computed at all levels of theory. Our CCSD(T)/aug-cc-pVQZ adiabatic electron affinity of 2.34eV for the Si2H radical is in excellent agreement with the photoelectron spectroscopy experiments of Xu et al. [J. Chem. Phys. 108, 7645 (1998)], where the electron affinity was determined to be 2.31±0.01eV.

  10. Analysis of electron donors in photosystems in oxygenic photosynthesis by photo-CIDNP MAS NMR.

    PubMed

    Najdanova, M; Janssen, G J; de Groot, H J M; Matysik, J; Alia, A

    2015-11-01

    Both photosystem I and photosystem II are considerably similar in molecular architecture but they operate at very different electrochemical potentials. The origin of the different redox properties of these RCs is not yet clear. In recent years, insight was gained into the electronic structure of photosynthetic cofactors through the application of photochemically induced dynamic nuclear polarization (photo-CIDNP) with magic-angle spinning NMR (MAS NMR). Non-Boltzmann populated nuclear spin states of the radical pair lead to strongly enhanced signal intensities that allow one to observe the solid-state photo-CIDNP effect from both photosystem I and II from isolated reaction center of spinach (Spinacia oleracea) and duckweed (Spirodela oligorrhiza) and from the intact cells of the cyanobacterium Synechocystis by (13)C and (15)N MAS NMR. This review provides an overview on the photo-CIDNP MAS NMR studies performed on PSI and PSII that provide important ingredients toward reconstruction of the electronic structures of the donors in PSI and PSII. PMID:26282679

  11. UPLC-TOF-MS Characterization and Identification of Bioactive Iridoids in Cornus mas Fruit

    PubMed Central

    West, Brett J.; Jensen, C. Jarakae

    2013-01-01

    Cornus mas L. is indigenous to Europe and parts of Asia. Although Cornus is widely considered to be an iridoid rich genera, only two iridoids have been previously found in this plant. The lack of information on taxonomically and biologically active iridoids prompted us to develop and optimize an analytical method for characterization of additional phytochemicals in C. mas fruit. An ultra performance liquid chromatography (UPLC) coupled with photodiode array spectrophotometry (PDA) and electrospray time-of-flight mass spectrometry (ESI-TOF-MS) was employed and mass parameters were optimized. Identification was made by elucidating the mass spectral data and further confirmed by comparing retention times and UV spectra of target peaks with those of reference compounds. Primary DNA damage and antigenotoxicity tests in E. coli PQ37 were used to screen the iridoids for biological activity. As a result, ten phytochemicals were identified, including iridoids loganic acid, loganin, sweroside, and cornuside. Nine of these were reported for the first time from C. mas fruit. The iridoids did not induce SOS repair of DNA, indicating a lack of genotoxic activity in E. coli PQ37. However, loganin, sweroside, and cornuside did reduce the amount of DNA damage caused by 4-nitroquinoline 1-oxide, suggesting potential antigenotoxic activity. PMID:24228188

  12. Conformation analysis and molecular mobility of ethylene and tetrafluoroethylene copolymer using solid-state 19F MAS and 1H --> 19F CP/MAS NMR spectroscopy.

    PubMed

    Aimi, Keitaro; Ando, Shinji

    2004-07-01

    The changes in the conformation and molecular mobility accompanied by a phase transition in the crystalline domain were analyzed for ethylene (E) and tetrafluoroethylene (TFE) copolymer, ETFE, using variable-temperature (VT) solid-state 19F magic angle spinning (MAS) and 1H --> 19F cross-polarization (CP)/MAS NMR spectroscopy. The shifts of the signals for fluorines in TFE units to higher frequency and the continuing decrease and increase in the T1rho(F) values suggest that conformational exchange motions exist in the crystalline domain between 42 and 145 degrees C. Quantum chemical calculations of magnetic shielding constants showed that the high-frequency shift of TFE units should be induced by trans to gauche conformational changes at the CH2-CF2 linkage in the E-TFE unit. Although the 19F signals of the crystalline domain are substantially overlapped with those of the amorphous domain at ambient probe temperature (68 degrees C), they were successfully distinguished by using the dipolar filter and spin-lock pulse sequences at 145 degrees C. The dipolar coupling constants for the crystalline domain, which can be estimated by fitting the dipolar oscillation behaviors in the 1H --> 19F CP curve, showed a significant decrease with increasing temperature from 42 to 145 degrees C. This is due to the averaging of 1H-19F dipolar interactions originating from the molecular motion in the crystalline domain. The increase in molecular mobility in the crystalline domain was clearly shown by VT T1rho(F) and 1H --> 19F CP measurements in the phase transition temperature range. PMID:15181627

  13. Protective Effect of Cornus mas Fruits Extract on Serum Biomarkers in CCl4-Induced Hepatotoxicity in Male Rats

    PubMed Central

    Alavian, Seyed Moayed; Banihabib, Nafiseh; Es. Haghi, Masoud; Panahi, Farid

    2014-01-01

    Background: Nowadays attention to use herbs such as cornelian cherry (Cornus mas) is increasing, which contains high levels of antioxidants and anthocyanins. Cornus mas fruits have been used for gastrointestinal and excretory disorders for many years in traditional medicine, also may improve liver and kidney functions, and have protective effects such as anti-allergic, antidiabetic, antibacterial, antimicrobial, antihistamine and antimalarial properties. Objectives: The aim of this study was to investigate protective effects of Cornus mas fruits extract on serum biomarkers in CCl4-induced hepatotoxicity in male rats. Materials and Methods: Hepatotoxicity was induced by administration of carbon tetrachloride (1 mL/kg i.p.) in 1:1 dilution with olive oil. To evaluate the effect of Cornus mas fruits extract on disease progression, serum marker enzymes, serum total protein and albumin and liver lipid peroxidation were determined in CCl4-induced hepatotoxicity. Results: Oral administration of Cornus mas fruits extract to rats for 14 days provided a significant (P < 0.05) hepatoprotection by decreasing elevated serum level of enzymes, total serum protein, albumin and liver lipid peroxidation content. Conclusions: Cornus mas fruit extract effect may be due to including some antioxidant components, which caused membrane stabilizing and normalization of fluctuated biochemical profiles induced by CCl4 exposure. Our results validated the traditional use of Cornus mas in the treatment of liver disorders. PMID:24829584

  14. Phase Cycling Schemes for finite-pulse-RFDR MAS Solid State NMR Experiments

    PubMed Central

    Zhang, Rongchun; Nishiyama, Yusuke; Sun, Pingchuan; Ramamoorthy, Ayyalusamy

    2015-01-01

    The finite-pulse radio frequency driven dipolar recoupling (fp-RFDR) pulse sequence is used in 2D homonuclear chemical shift correlation experiments under magic angle spinning (MAS). A recent study demonstrated the advantages of using a short phase cycle, XY4, and its super-cycle, XY414, for the fp-RFDR pulse sequence employed in 2D 1H/1H single-quantum/single-quantum correlation experiments under ultrafast MAS conditions. In this study, we report a comprehensive analysis on the dipolar recoupling efficiencies of XY4, XY412, XY413, XY414, and XY814 phase cycles under different spinning speeds ranging from 10 to 100 kHz. The theoretical calculations reveal the presence of second-order terms (T10T2,±2, T1,±1T2,±1, etc.) in the recoupled homonuclear dipolar coupling Hamiltonian only when the basic XY4 phase cycle is utilized, making it advantageous for proton-proton magnetization transfer under ultrafast MAS conditions. It is also found that the recoupling efficiency of fp-RFDR is quite dependent on the duty factor (τ180/τR) as well as on the strength of homonuclear dipolar couplings. The rate of longitudinal magnetization transfer increases linearly with the duty factor of fp-RFDR for all the XY-based phase cycles investigated in this study. Examination of the performances of different phase cycles against chemical shift offset and RF field in homogeneity effects revealed that XY414 is the most tolerant phase cycle, while the shortest phase cycle XY4 suppressed the RF field inhomogeneity effects most efficiently under slow spinning speeds. Our results suggest that the difference in the fp-RFDR recoupling efficiencies decreases with the increasing MAS speed, while ultrafast (>60 kHz) spinning speed is advantageous as it recouples a large amount of homonuclear dipolar couplings and therefore enable fast magnetization exchange. The effects of higher-order terms and cross terms between various interactions in the effective Hamiltonian of fp-RFDR are also analyzed

  15. Synthesis of [.sup.13C] and [.sup.2H] substituted methacrylic acid, [.sup.13C] and [.sup.2H] substituted methyl methacrylate and/or related compounds

    DOEpatents

    Alvarez, Marc A.; Martinez, Rodolfo A.; Unkefer, Clifford J.

    2008-01-22

    The present invention is directed to labeled compounds of the formulae ##STR00001## wherein Q is selected from the group consisting of --S--, --S(.dbd.O)--, and --S(.dbd.O).sub.2--, Z is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently selected from the group consisting of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group selected from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each independently selected from the group consisting of a C.sub.1-C.sub.4 lower alkyl, an aryl, and an alkoxy group, and X is selected from the group consisting of hydrogen, a C.sub.1-C.sub.4 lower alkyl group, and a fully-deuterated C.sub.1-C.sub.4 lower alkyl group. The present invention is also directed to a process of preparing labeled compounds, e.g., process of preparing [.sup.13C]methacrylic acid by reacting a (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13CH.sub.2)-- aryl sulfone precursor with .sup.13CHI to form a (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13C(.sup.13CH.sub.3).sub.2)-- aryl sulfone intermediate, and, reacting the (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13C(.sup.13CH.sub.3).sub.2)-- aryl sulfone intermediate with sodium hydroxide, followed by acid to form [.sup.13C]methacrylic acid. The present invention is further directed to a process of preparing [.sup.2H.sub.8]methyl methacrylate by reacting a (HOOC--C(C.sup.2H.sub.3).sub.2-- aryl sulfinyl intermediate with CD.sub.3I to form a (.sup.2H.sub.3COOC--C(C.sup.2H.sub.3).sub.2)-- aryl sulfinyl intermediate, and heating the(.sup.2H.sub.3COOC--C(C.sup.2H.sub.3).sub.2)-- aryl sulfinyl intermediate at temperatures and for time sufficient to form [.sup.2H.sub.8]methyl methacrylate.

  16. Chromatin remodeling enzyme Snf2h regulates embryonic lens differentiation and denucleation.

    PubMed

    He, Shuying; Limi, Saima; McGreal, Rebecca S; Xie, Qing; Brennan, Lisa A; Kantorow, Wanda Lee; Kokavec, Juraj; Majumdar, Romit; Hou, Harry; Edelmann, Winfried; Liu, Wei; Ashery-Padan, Ruth; Zavadil, Jiri; Kantorow, Marc; Skoultchi, Arthur I; Stopka, Tomas; Cvekl, Ales

    2016-06-01

    Ocular lens morphogenesis is a model for investigating mechanisms of cellular differentiation, spatial and temporal gene expression control, and chromatin regulation. Brg1 (Smarca4) and Snf2h (Smarca5) are catalytic subunits of distinct ATP-dependent chromatin remodeling complexes implicated in transcriptional regulation. Previous studies have shown that Brg1 regulates both lens fiber cell differentiation and organized degradation of their nuclei (denucleation). Here, we employed a conditional Snf2h(flox) mouse model to probe the cellular and molecular mechanisms of lens formation. Depletion of Snf2h induces premature and expanded differentiation of lens precursor cells forming the lens vesicle, implicating Snf2h as a key regulator of lens vesicle polarity through spatial control of Prox1, Jag1, p27(Kip1) (Cdkn1b) and p57(Kip2) (Cdkn1c) gene expression. The abnormal Snf2h(-/-) fiber cells also retain their nuclei. RNA profiling of Snf2h(-/) (-) and Brg1(-/-) eyes revealed differences in multiple transcripts, including prominent downregulation of those encoding Hsf4 and DNase IIβ, which are implicated in the denucleation process. In summary, our data suggest that Snf2h is essential for the establishment of lens vesicle polarity, partitioning of prospective lens epithelial and fiber cell compartments, lens fiber cell differentiation, and lens fiber cell nuclear degradation. PMID:27246713

  17. Absorption of 3(2H)-furanones by human intestinal epithelial Caco-2 cells.

    PubMed

    Stadler, Nicole Christina; Somoza, Veronika; Schwab, Wilfried

    2009-05-13

    A number of 3(2H)-furanones are synthesized by fruits and have been found in cooked foodstuffs, where they impart flavor and odor because of their low perception thresholds. They show genotoxic properties in model studies but are also ranked among the antioxidants and anticarcinogens. This study examined the efficiency of intestinal absorption and metabolic conversion of 3(2H)-furanones by using Caco-2 cell monolayers as an intestinal epithelial cell model. The permeability of each agent was measured in both the apical to basal and basal to apical directions. 2,5-Dimethyl-4-methoxy-3(2H)-furanone (DMMF) showed the highest absorption rate in all experiments, while similar amounts of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF), and 4-hydroxy-5-methyl-3(2H)-furanone (HMF) were taken up. HDMF-glucoside was almost not absorbed but was hydrolyzed to a small extent. The transport of 3(2H)-furanones could not be saturated even at levels of 500 microM and occurred in both directions. Because the uptake was only slightly reduced by apical hyperosmolarity, passive diffusion by paracellular transport is proposed. PMID:19338346

  18. A Ring of C2H in the Protoplanetary Disk Orbiting TW Hya

    NASA Astrophysics Data System (ADS)

    Kastner, Joel H.; Qi, Chunhua; Gorti, Uma; Hily-Blant, Pierre; Forveille, Thierry; Oberg, Karin I.

    2015-01-01

    The circumstellar disk orbiting the nearby (D = 54 pc), ~8 Myr-old, ~0.8 Msun classical T Tauri star TW Hya represents a rich source of information concerning the chemical composition of a protoplanetary disk in its late evolutionary stages, just at or after the epoch of giant planet formation. Following up on the detection of strong mm-wave C2H (4-3) emission from this disk via an unbiased single-dish line survey (Kastner et al. 2014, ApJ, 793, 55), we have used the SMA to image C2H (3-2) at ~1.5" resolution. We find the C2H emission emanates from a relatively narrow ring of inner radius ~1" (~50 AU). We consider various interpretations of this striking, ring-like C2H emission morphology, including whether C2H might serve as a disk "snow line" marker (as is the case for N2H+ Qi et al. 2013, Science, 341, 630) and the possibility that C2H traces particularly efficient photodissociation of hydrocarbons and/or the photoevaporation of small, C-rich grains in this region of the disk.

  19. Direct measurements of rate constants for the reactions of CH3 radicals with C2H6, C2H4, and C2H2 at high temperatures.

    PubMed

    Peukert, S L; Labbe, N J; Sivaramakrishnan, R; Michael, J V

    2013-10-10

    The shock tube technique has been used to study the reactions CH3 + C2H6 → C2H4 + CH4 + H (1), CH3 + C2H4 → Products + H (2), and CH3 + C2H2 → Products + H (3). Biacetyl, (CH3CO)2, was used as a clean high temperature thermal source for CH3-radicals for all the three reactions studied in this work. For reaction 1, the experiments span a T-range of 1153 K ≤ T ≤ 1297 K, at P ~ 0.4 bar. The experiments on reaction 2 cover a T-range of 1176 K ≤ T ≤ 1366 K, at P ~ 1.0 bar, and those on reaction 3 a T-range of 1127 K ≤ T ≤ 1346 K, at P ~ 1.0 bar. Reflected shock tube experiments performed on reactions 1-3, monitored the formation of H-atoms with H-atom Atomic Resonance Absorption Spectrometric (ARAS). Fits to the H-atom temporal profiles using an assembled kinetics model were used to make determinations for k1, k2, and k3. In the case of C2H6, the measurements of [H]-atoms were used to derive direct high-temperature rate constants, k1, that can be represented by the Arrhenius equation k1(T) = 5.41 × 10(-12) exp(-6043 K/T) cm(3) molecules(-1) s(-1) (1153 K ≤ T ≤ 1297 K) for the only bimolecular process that occurs, H-atom abstraction. TST calculations based on ab initio properties calculated at the CCSD(T)/CBS//M06-2X/cc-pVTZ level of theory show excellent agreement, within ±20%, of the measured rate constants. For the reaction of CH3 with C2H4, the present rate constant results, k2', refer to the sum of rate constants, k(2b) + k(2c), from two competing processes, addition-elimination, and the direct abstraction CH3 + C2H4 → C3H6 + H (2b) and CH3 + C2H4 → C2H2 + H + CH4 (2c). Experimental rate constants for k2' can be represented by the Arrhenius equation k2'(T) = 2.18 × 10(-10) exp(-11830 K/T) cm(3) molecules(-1) s(-1) (1176 K ≤ T ≤ 1366 K). The present results are in excellent agreement with recent theoretical predictions. The present study provides the only direct measurement for the high-temperature rate constants for these channels

  20. Optical emission spectroscopy study of premixed C2H4/O2 and C2H4/C2H2/O2 flames for diamond growth with and without CO2 laser excitation

    NASA Astrophysics Data System (ADS)

    He, X. N.; Gebre, T.; Shen, X. K.; Xie, Z. Q.; Zhou, Y. S.; Lu, Y. F.

    2010-02-01

    Optical emission spectroscopy (OES) measurements were carried out to study premixed C2H4/O2 and C2H4/C2H2/O2 combustion flame for diamond deposition with and without a CO2 laser excitation. Strong emissions from radicals C2 and CH were observed in the visible range in all the OES spectra acquired. By adding a continuous-wave CO2 laser to irradiate the flame at a wavelength of 10.591 μm, the common CO2 laser wavelength, it was discovered that the emission intensities of the C2 and CH radicals were increased due to the laser beam induced excitation. OES measurements of the C2 and CH radicals were performed using different gas combinations and laser powers. The rotational temperatures in the flame were determined by analyzing the spectra of the R-branch of the A2Δ-->X2Π (0, 0) electronic transition near 430 nm (CH band head). Information obtained from the OES spectra, including the emission intensities of the C2 and CH radicals, the intensity ratios, and the rotational temperatures, was integrated into the study of diamond deposition on tungsten carbide substrates for mechanism analysis of the laser induced vibrational excitation and laser-assisted diamond deposition.

  1. C(2)H(4): Its Incorporation and Metabolism by Pea Seedlings under Aseptic Conditions.

    PubMed

    Beyer, E M

    1975-08-01

    The effects of various treatments on the recently reported system in pea (Pisum sativum cv. Alaska), which results in (a) the incorporation of (14)C(2)H(4) into the tissue and (b) the conversion of (14)C(2)H(4) to (14)CO(2), was investigated using 2-day-old etiolated seedlings which exhibit a maximum response. Heat treatment (80 C, 1 min) completely inhibited both a and b, whereas homogenization completely inhibited b but only partially inhibited a. Detaching the cotyledons from the root-shoot axis immediately before exposing the detached cotyledons together with the root-shoot axis to (14)C(2)H(4) markedly reduced both a and b. Increasing the (14)C(2)H(4) concentration from 0.14 to over 100 mul/l progressively increased the rate of a and b with tissue incorporation being greater than (14)C(2)H(4) to (14)CO(2) conversion only below 0.3 mul/l (14)C(2)H(4). Reduction of the O(2) concentration reduced both a and b, with over 99% inhibition occurring under anaerobic conditions. The addition of CO(2) (5%) severely inhibited (14)C(2)H(4) to (14)CO(2) conversion without significantly affecting tissue incorporation. Exposure of etiolated seedlings to fluorescent light during (14)C(2)H(4) treatment was without effect. Similarly, indoleacetic acid, gibberellic acid, benzyladenine, abscisic acid, and dibutyryl cyclic adenosine monophosphate had no significant effect on either a or b.The possibilities that the incorporation of (14)C(2)H(4) into pea tissues and its conversion to (14)CO(2) is linked to ethylene action, or that it represents a means of reducing the endogenous ethylene level, are discussed.Several problems encountered with the use of polyethylene vials, rubber serum stoppers, Clorox, and microbial contamination are also described. PMID:16659286

  2. New determination of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reaction rates at astrophysical energies

    SciTech Connect

    Tumino, A.; Spartà, R.; Spitaleri, C.; Pizzone, R. G.; La Cognata, M.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Mukhamedzhanov, A. M.; Typel, S.; Tognelli, E.; Degl'Innocenti, S.; Prada Moroni, P. G.; Burjan, V.; Kroha, V.; Hons, Z.; Mrazek, J.; Piskor, S.; Lamia, L.

    2014-04-20

    The cross sections of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured via the Trojan Horse method applied to the quasi-free {sup 2}H({sup 3}He,p {sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n {sup 3}He){sup 1}H processes at 18 MeV off the proton in {sup 3}He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the {sup 2}H(d,n){sup 3}He reaction is quite influential on {sup 7}Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (≤1 Myr) with masses ≥1 M {sub ☉}.

  3. New Determination of the 2H(d,p)3H and 2H(d,n)3He Reaction Rates at Astrophysical Energies

    NASA Astrophysics Data System (ADS)

    Tumino, A.; Spartà, R.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Pizzone, R. G.; Tognelli, E.; Degl'Innocenti, S.; Burjan, V.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Mrazek, J.; Piskor, S.; Prada Moroni, P. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

    2014-04-01

    The cross sections of the 2H(d,p)3H and 2H(d,n)3He reactions have been measured via the Trojan Horse method applied to the quasi-free 2H(3He,p 3H)1H and 2H(3He,n 3He)1H processes at 18 MeV off the proton in 3He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the 2H(d,n)3He reaction is quite influential on 7Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (<=1 Myr) with masses >=1 M ⊙.

  4. Homotopy Algorithm for Fixed Order Mixed H2/H(infinity) Design

    NASA Technical Reports Server (NTRS)

    Whorton, Mark; Buschek, Harald; Calise, Anthony J.

    1996-01-01

    Recent developments in the field of robust multivariable control have merged the theories of H-infinity and H-2 control. This mixed H-2/H-infinity compensator formulation allows design for nominal performance by H-2 norm minimization while guaranteeing robust stability to unstructured uncertainties by constraining the H-infinity norm. A key difficulty associated with mixed H-2/H-infinity compensation is compensator synthesis. A homotopy algorithm is presented for synthesis of fixed order mixed H-2/H-infinity compensators. Numerical results are presented for a four disk flexible structure to evaluate the efficiency of the algorithm.

  5. Determination of the delta(2H/1H)of Water: RSIL Lab Code 1574

    USGS Publications Warehouse

    Revesz, Kinga; Coplen, Tyler B.

    2008-01-01

    Reston Stable Isotope Laboratory (RSIL) lab code 1574 describes a method used to determine the relative hydrogen isotope-ratio delta(2H,1H), abbreviated hereafter as d2H of water. The d2H measurement of water also is a component of the National Water Quality Laboratory (NWQL) schedules 1142 and 1172. The water is collected unfiltered in a 60-mL glass bottle and capped with a Polyseal cap. In the laboratory, the water sample is equilibrated with gaseous hydrogen using a platinum catalyst (Horita, 1988; Horita and others, 1989; Coplen and others, 1991). The reaction for the exchange of one hydrogen atom is shown in equation 1.

  6. Relative high-resolution absorption cross sections of C2H6 at low temperatures

    NASA Astrophysics Data System (ADS)

    Hargreaves, R. J.; Bernath, P. F.; Appadoo, D. R. T.

    2015-09-01

    Synchrotron radiation has been used to record absorption cross sections of ethane, C2H6, in the far-infrared with very high spectral resolution (up to 0.00096 cm-1). C2H6 is present in the atmospheres of the Gas Giant planets and Titan but the vapor pressure at relevant atmospheric temperatures (i.e., between 70 and 200 K) is low. This makes laboratory measurements difficult. We demonstrate the effectiveness of a unique "enclosive flow" cold cell, located at the Australian Synchrotron, that enables high-resolution absorption cross sections of gaseous C2H6 to be recorded at 90 K.

  7. A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

    PubMed Central

    Mikhalchenko, Oksana S; Korchagina, Dina V; Salakhutdinov, Nariman F

    2016-01-01

    Summary Conditions enabling the single-step preparative synthesis of chiral 4-fluoropolyhydro-2H-chromenes in good yields through a reaction between monoterpenoid alcohols with para-menthane skeleton and aldehydes were developed for the first time. The BF3·Et2O/H2O system is used both as a catalyst and as a fluorine source. The reaction can involve aliphatic aldehydes as well as aromatic aldehydes containing various acceptor and donor substituents. 4-Hydroxyhexahydro-2H-chromenes were demonstrated to be capable of converting to 4-fluorohexahydro-2H-chromenes under the developed conditions, the reaction occurs with inversion of configuration. PMID:27340456

  8. Kinetic Resolution of 2H-Azirines by Asymmetric Imine Amidation.

    PubMed

    Hu, Haipeng; Liu, Yangbin; Lin, Lili; Zhang, Yuheng; Liu, Xiaohua; Feng, Xiaoming

    2016-08-16

    Highly efficient kinetic resolution of 2H-azirines by an asymmetric imine amidation was achieved in the presence of a chiral N,N'-dioxide/Sc(III) complex, thus providing a promising method to obtain the enantioenriched 2H-azirine derivatives and protecting-group free aziridines at the same time. It is rare to find an example of N1 of an oxindole participating in a reaction over C3. Moreover, chiral 2H-azirines were stereospecifically transformed into an unprotected aziridine and α-amino ketone. PMID:27384910

  9. High-resolution spectroscopy of Saturn at 3 microns: CH 4, CH 3D, C 2H 2, C 2H 6, PH 3, clouds, and haze

    NASA Astrophysics Data System (ADS)

    Kim, Joo Hyeon; Kim, Sang J.; Geballe, Thomas R.; Kim, Sungsoo S.; Brown, Linda R.

    2006-12-01

    We report observation and analysis of a high-resolution 2.87-3.54 μm spectrum of the southern temperate region of Saturn obtained with NIRSPEC at Keck II. The spectrum reveals absorption and emission lines of five molecular species as well as spectral features of haze particles. The ν+ν band of CH 3D is detected in absorption between 2.87 and 2.92 μm; and we derived from it a mixing ratio approximately consistent with the Infrared Space Observatory result. The ν band of C 2H 2 also is detected in absorption between 2.95 and 3.05 μm; analysis indicates a sudden drop in the C 2H 2 mixing ratio at 15 mbar (130 km above the 1 bar level), probably due to condensation in the low stratosphere. The presence of the ν+ν+ν band of C 2H 6 near 3.07 μm, first reported by Bjoraker et al. [Bjoraker, G.L., Larson, H.P., Fink, U., 1981. Astrophys. J. 248, 856-862], is confirmed, and a C 2H 6 condensation altitude of 10 mbar (140 km) in the low stratosphere is determined. We assign weak emission lines within the 3.3 μm band of CH 4 to the ν band of C 2H 6, and derive a mixing ratio of 9±4×10 for this species. Most of the C 2H 6 3.3 μm line emission arises in the altitude range 460-620 km (at ˜μbar pressure levels), much higher than the 160-370 km range where the 12 μm thermal molecular line emission of this species arises. At 2.87-2.90 μm the major absorber is tropospheric PH 3. The cloud level determined here and at 3.22-3.54 is 390-460 mbar (˜30 km), somewhat higher than found by Kim and Geballe [Kim, S.J., Geballe, T.R., 2005. Icarus 179, 449-458] from analysis of a low resolution spectrum. A broad absorption feature at 2.96 μm, which might be due to NH 3 ice particles in saturnian clouds, is also present. The effect of a haze layer at about 125 km (˜12 mbar level) on the 3.20-3.54 μm spectrum, which was not apparent in the low resolution spectrum, is clearly evident in the high resolution data, and the spectral properties of the haze particles suggest that

  10. Review of 2H-tetraphenylporphyrins metalation in ultra-high vacuum on metal surfaces

    NASA Astrophysics Data System (ADS)

    Panighel, M.; Di Santo, G.; Caputo, M.; Lal, C.; Taleatu, B.; Goldoni, A.

    2013-12-01

    The formation and conformational adaptation of self-assembled monolayer of 2H-tetraphenylporphyrins (2H-TPPs) on metal surfaces, as well as their metalation processes in ultra-high vacuum (UHV), are reviewed. By means of XPS, NEXAFS and STM measurements we demonstrate that, after the annealing at 550 K, a temperature-induced chemical modification of 2H-TPP monolayer on Ag(111) occurs, resulting in the rotation of the phenyl rings parallel to the substrate plane. Moreover, independently of the conformation, we report three different methods to metalate 2H-TPP monolayers in UHV. Experimental evidence indicates that the presence of a metal atom in the TPP macrocycle influences both the conformation of the molecule and its adsorption distance.

  11. Indirect Approach To The {sup 2}H(d,p){sup 3}H Reaction Study

    SciTech Connect

    Sparta, R.; Pizzone, R. G.; Spitaleri, C.; Cherubini, S.; Crucilla, V.; Gulino, M.; La Cognata, M.; Lamia, L.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Aliotta, M.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Kiss, G.; McCleskey, M.; Trache, L.

    2010-11-24

    In order to understand primordial and stellar nucleosynthesis, we have studied {sup 2}H(d,p){sup 3}H reaction at 0.4 MeV down to astrophysical energies. Knowledge of its S-factor is interesting also to plan reactions for fusion reactors to produce energy. The {sup 2}H(d,p)H reaction has been studied through the Trojan Horse Method applied to the three-body reaction {sup 2}H(He,pt)H, at beam energy of 17 MeV. Once selection of protons and tritons detected in coincidence and the selection of quasi-free events, the obtained S-factor is compared with direct measurements. Such data are in agreement with the direct ones and a pole invariance test has been obtained comparing the present results with another {sup 2}H(d,p){sup 3}H THM measurements, where a different spectator particle was employed.

  12. Ecocatalysis for 2H-chromenes synthesis: an integrated approach for phytomanagement of polluted ecosystems.

    PubMed

    Escande, Vincent; Velati, Alicia; Grison, Claude

    2015-04-01

    A direct, general and efficient method to synthesize 2H-chromenes (2H-benzo[b]pyrans), identified as environmentally friendly pesticides, has been developed. This approach lays on the new concept of ecocatalysis, which involves the use of biomass from phytoextraction processes, as a valuable source of metallic elements for chemical synthesis. This methodology is similar or superior to known methods, affording 2H-chromenes with good to excellent yields (60-98%), including the preparation of precocene I, a natural insect growth regulator, with 91% yield. The approach is ideal for poor reactive substrates such as phenol or naphthol, classically transformed into 2H-chromenes by methodologies associated with environmental issues. These results illustrate the interest of combining phytoextraction and green synthesis of natural insecticides. PMID:25131683

  13. Oxydifluoromethylation of Alkenes by Photoredox Catalysis: Simple Synthesis of CF2H-Containing Alcohols.

    PubMed

    Arai, Yusuke; Tomita, Ren; Ando, Gaku; Koike, Takashi; Akita, Munetaka

    2016-01-22

    We have developed a novel and simple protocol for the direct incorporation of a difluoromethyl (CF2 H) group into alkenes by visible-light-driven photoredox catalysis. The use of fac-[Ir(ppy)3] (ppy=2-pyridylphenyl) photocatalyst and shelf-stable Hu's reagent, N-tosyl-S-difluoromethyl-S-phenylsulfoximine, as a CF2 H source is the key to success. The well-designed photoredox system achieves synthesis of not only β-CF2 H-substituted alcohols but also ethers and an ester from alkenes through solvolytic processes. The present method allows a single-step and regioselective formation of C(sp(3))-CF2 H and C(sp(3))-O bonds from C=C moiety in alkenes, such as hydroxydifluoromethylation, regardless of terminal or internal alkenes. Moreover, this methodology tolerates a variety of functional groups. PMID:26639021

  14. Alcohol binding to liposomes by 2H NMR and radiolabel binding assays: does partitioning describe binding?

    PubMed Central

    Dubey, A K; Eryomin, V A; Taraschi, T F; Janes, N

    1996-01-01

    Implicit within the concept of membrane-buffer partition coefficients of solutes is a nonspecific solvation mechanism of solute binding. However, (2)H NMR studies of the binding of (2)H(6)-ethanol and [1-(2)H(2)] n-hexanol to phosphatidylcholine vesicles have been interpreted as evidence for two distinct alcohol binding modes. One binding mode was reported to be at the membrane surface. The second mode was reported to be within the bilayer interior. An examination of the (2)H NMR binding studies, together with direct radiolabel binding assays, shows that other interpretations of the data are more plausible. The results are entirely consistent with partitioning (nonspecific binding) as the sole mode of alcohol binding to liposomes, in accord with our previous thermodynamic interpretation of alcohol action in phosphatidylcholine liposomes. PMID:9172754

  15. Rings of C2H in the Molecular Disks Orbiting TW Hya and V4046 Sgr

    NASA Astrophysics Data System (ADS)

    Kastner, J. H.; Qi, C.; Gorti, U.; Hily-Blant, P.; Oberg, K.; Forveille, T.; Andrews, S.; Wilner, D.

    2016-01-01

    We have used the Submillimeter Array (SMA) to image, at ~1'' resolution, C2H(3-2) emission from the molecule-rich circumstellar disks orbiting the nearby, classical T Tauri star systems TW Hya and V4046 Sgr. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology within each disk; the radius of the inner hole of the C2H ring within the V4046 Sgr disk (~70 AU) is somewhat larger than than of its counterpart within the TW Hya disk (~45 AU). We suggest that, in each case, the C2H emission likely traces irradiation of the tenuous surface layers of the outer disks by high-energy photons from the central stars.

  16. Infrared and Ultraviolet Spectra of Diborane(6): B2H6 and B2D6.

    PubMed

    Peng, Yu-Chain; Chou, Sheng-Lung; Lo, Jen-Iu; Lin, Meng-Yeh; Lu, Hsiao-Chi; Cheng, Bing-Ming; Ogilvie, J F

    2016-07-21

    We recorded absorption spectra of diborane(6), B2H6 and B2D6, dispersed in solid neon near 4 K in both mid-infrared and ultraviolet regions. For gaseous B2H6 from 105 to 300 nm, we report quantitative absolute cross sections; for solid B2H6 and for B2H6 dispersed in solid neon, we measured ultraviolet absorbance with relative intensities over a wide range. To assign the mid-infrared spectra to specific isotopic variants, we applied the abundance of (11)B and (10)B in natural proportions; we undertook quantum-chemical calculations of wavenumbers associated with anharmonic vibrational modes and the intensities of the harmonic vibrational modes. To aid an interpretation of the ultraviolet spectra, we calculated the energies of electronically excited singlet and triplet states and oscillator strengths for electronic transitions from the electronic ground state. PMID:27351464

  17. Synthesis of 2H-Indazoles by the [3 + 2] Dipolar Cycloaddition of Sydnones with Arynes

    PubMed Central

    Fang, Yuesi; Wu, Chunrui; Larock, Richard C.; Shi, Feng

    2011-01-01

    A rapid and efficient synthesis of 2H-indazoles has been developed using a [3 + 2] dipolar cycloaddition of sydnones and arynes. A series of 2H-indazoles have been prepared in good to excellent yields using this protocol, and subsequent Pd-catalyzed coupling reactions can be applied to the halogenated products to generate a structurally diverse library of indazoles. PMID:21970468

  18. A Ring of C2H in the Molecular Disk Orbiting TW Hya

    NASA Astrophysics Data System (ADS)

    Kastner, Joel H.; Qi, Chunhua; Gorti, Uma; Hily-Blant, Pierre; Oberg, Karin; Forveille, Thierry; Andrews, Sean; Wilner, David

    2015-06-01

    We have used the Submillimeter Array to image, at ˜1.″5 resolution, C2H N=3\\to 2 emission from the circumstellar disk orbiting the nearby (D = 54 pc), ˜8 Myr-old, ˜0.8 {{M}⊙ } classical T Tauri star TW Hya. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology. Based on a model in which the C2H column density follows a truncated radial power-law distribution, we find that the inner edge of the ring lies at ˜45 AU, and that the ring extends to at least ˜120 AU. Comparison with previous (single-dish) observations of C2H N=4\\to 3 emission indicates that the C2H molecules are subthermally excited and, hence, that the emission arises from the relatively warm (T≳ 40 K), tenuous (n\\ll {{10}7} cm-3) upper atmosphere of the disk. Based on these results and comparisons of the SMA C2H map with previous submillimeter and scattered-light imaging, we propose that the C2H emission most likely traces particularly efficient photo-destruction of small grains and/or photodesorption and photodissociation of hydrocarbons derived from grain ice mantles in the surface layers of the outer disk. The presence of a C2H ring in the TW Hya disk hence likely serves as a marker of dust grain processing and radial and vertical grain size segregation within the disk.

  19. SLOW-MAS NMR METHODS TO STUDY METABOLIC PROCESSES IN VIVO AND IN VITRO

    SciTech Connect

    Wind, Robert A.; Bertram, Hanne Christine; Hu, Jian Zhi

    2005-09-25

    In vitro and in vivo 1H NMR spectroscopy is widely used to measure metabolic profiles in cells, tissues, animals, and humans and to use them, e.g., for diagnosis and therapy response evaluations. However, the spectra often suffer from poor resolution due to variations in the isotropic bulk magnetic susceptibility present in biological objects, resulting in a broadening of the NMR lines. In principle this broadening can be averaged to zero by the technique of magic angle spinning (MAS), where the sample is rotated about an axis making an angle of 54o44’ relative to the external magnetic field. However, a problem is that in a standard MAS experiment spinning speeds of a kHz or more are required in order to avoid the occurrence of spinning sidebands (SSBs) in the spectra, which renders analysis of the spectra difficult again. At these spinning speeds the large centrifugal forces cause severe structural damage in larger biological objects, so that this method cannot be used to study metabolic processes in intact samples. In solid state NMR several methods have been developed where slow MAS is combined with special radio frequency pulse sequences to eliminate spinning side bands or separate them from the isotropic spectrum so that a SSB-free high-resolution isotropic spectrum is obtained. It has been shown recently that two methods, phase-adjusted spinning sidebands (PASS) and phase-corrected magic angle turning (PHORMAT), can successfully be modified for applications in biological materials (1, 2). With PASS MAS speeds as low as 40 Hz can be employed, allowing non or minimally invasive in vitro studies of excised tissues and organs. This method was used, amongst other things, to study post mortem changes in the proton metabolite spectra in excised rabbit muscle tissue (3). With PHORMAT the NMR sensitivity is reduced and longer measuring times are required, but with this methodology the MAS speed can be reduced to ~1 Hz. This makes PHORMAT amenable for in vivo

  20. 1H, 13C MAS NMR and GIAO-CPHF calculations of chloramphenicol, thiamphenicol and their pyrrole analogues

    NASA Astrophysics Data System (ADS)

    Żołek, Teresa; Paradowska, Katarzyna; Krajewska, Dorota; Różański, Andrzej; Wawer, Iwona

    2003-02-01

    The 13C CP MAS and 1H MAS NMR and ab initio (GIAO-CPHF) calculations were used to obtain structural information on two known antibiotics: chloramphenicol, and thiamphenicol, and two new analogues: DL- threo-1-(1-methyl-4-nitro-pyrrole-2-yl)-2-dichloroacetamidopropane-1,3-diol and DL- threo-1-(1-methylsulfonylpyrrole-3-yl)-2-dichloroacetamidopropane-1,3-diol.

  1. Role of Mas receptor antagonist (A779) in renal hemodynamics in condition of blocked angiotensin II receptors in rats.

    PubMed

    Mansoori, A; Oryan, S; Nematbakhsh, M

    2016-03-01

    The vasodilatory effect of angiotensin 1-7 (Ang 1-7) is exerted in the vascular bed via Mas receptor (MasR) gender dependently. However, the crosstalk between MasR and angiotensin II (Ang II) types 1 and 2 receptors (AT1R and AT2R) may change some actions of Ang 1-7 in renal circulation. In this study by blocking AT1R and AT2R, the role of MasR in kidney hemodynamics was described. In anaesthetized male and female Wistar rats, the effects of saline as vehicle and MasR blockade (A779) were tested on mean arterial pressure (MAP), renal perfusion pressure (RPP), renal blood flow (RBF), and renal vascular resistance (RVR) when both AT1R and AT2R were blocked by losartan and PD123319, respectively. In male rats, when AT1R and AT2R were blocked, there was a tendency for the increase in RBF/wet kidney tissue weight (RBF/KW) to be elevated by A779 as compared with the vehicle (P=0.08), and this was not the case in female rats. The impact of MasR on renal hemodynamics appears not to be sexual dimorphism either when Ang II receptors were blocked. It seems that co-blockade of all AT1R, AT2R, and MasR may alter RBF/ KW in male more than in female rats. These findings support a crosstalk between MasR and Ang II receptors in renal circulation. PMID:27030624

  2. C2H4 adsorption on Cu(210), revisited: bonding nature and coverage effects.

    PubMed

    Amino, Shuichi; Arguelles, Elvis; Agerico Diño, Wilson; Okada, Michio; Kasai, Hideaki

    2016-08-24

    With the aid of density functional theory (DFT)-based calculations, we investigate the adsorption of C2H4 on Cu(210). We found two C2H4 adsorption sites, viz., the top of the step-edge atom (S) and the long bridge between two step-edge atoms (SS) of Cu(210). The step-edge atoms on Cu(210) block the otherwise active terrace sites found on copper surfaces with longer step sizes. This results in the preference for π-bonded over di-σ-bonded C2H4. We also found two stable C2H4 adsorption orientations on the S- and SS-sites, viz., with the C2H4 C[double bond, length as m-dash]C bond parallel (fit) and perpendicular (cross) to [001]. Furthermore, we found that the three peaks observed in previous temperature programmed desorption (TPD) experiment [Surf. Sci., 2011, 605, 934-940] could be attributed to C2H4 in the S-fit or S-cross, S-fit and S-cross-fit (S-cross and S-fit configurations that both exist in the same unit cell) configurations on Cu(210). PMID:27506302

  3. Broad N2H+ Emission toward the Protostellar Shock L1157-B1

    NASA Astrophysics Data System (ADS)

    Codella, C.; Viti, S.; Ceccarelli, C.; Lefloch, B.; Benedettini, M.; Busquet, G.; Caselli, P.; Fontani, F.; Gómez-Ruiz, A.; Podio, L.; Vasta, M.

    2013-10-01

    We present the first detection of N2H+ toward a low-mass protostellar outflow, namely, the L1157-B1 shock, at ~0.1 pc from the protostellar cocoon. The detection was obtained with the IRAM 30 m antenna. We observed emission at 93 GHz due to the J = 1-0 hyperfine lines. Analysis of this emission coupled with HIFI CHESS multiline CO observations leads to the conclusion that the observed N2H+(1-0) line originated from the dense (>=105 cm-3) gas associated with the large (20''-25'') cavities opened by the protostellar wind. We find an N2H+ column density of a few 1012 cm-2 corresponding to an abundance of (2-8) × 10-9. The N2H+ abundance can be matched by a model of quiescent gas evolved for more than 104 yr, i.e., for more than the shock kinematical age (sime2000 yr). Modeling of C-shocks confirms that the abundance of N2H+ is not increased by the passage of the shock. In summary, N2H+ is a fossil record of the pre-shock gas, formed when the density of the gas was around 104 cm-3, and then further compressed and accelerated by the shock.

  4. Variations in the Nature of Triple Bonds: The N2, HCN, and HC2H Series.

    PubMed

    Xu, Lu T; Dunning, Thom H

    2016-07-01

    The inertness of molecular nitrogen and the reactivity of acetylene suggest there are significant variations in the nature of triple bonds. To understand these differences, we performed generalized valence bond as well as more accurate electronic structure calculations on three molecules with putative triple bonds: N2, HCN, and HC2H. The calculations predict that the triple bond in HC2H is quite different from the triple bond in N2, with HCN being an intermediate case but closer to N2 than HC2H. The triple bond in N2 is a traditional triple bond with the spins of the electrons in the bonding orbital pairs predominantly singlet coupled in the GVB wave function (92%). In HC2H, however, there is a substantial amount of residual CH(a(4)Σ(-)) fragment coupling in the triple bond at its equilibrium geometry with the contribution of the perfect pairing spin function dropping to 82% (77% in a full valence GVB calculation). This difference in the nature of the triple bond in N2 and HC2H may well be responsible for the differences in the reactivities of N2 and HC2H. PMID:27299373

  5. Infrared spectrum of the disilane cation (Si2H6+) from Ar-tagging spectroscopy.

    PubMed

    Savoca, Marco; George, Martin Andreas Robert; Langer, Judith; Dopfer, Otto

    2013-02-28

    The infrared spectrum of the disilane cation, Si(2)H(6)(+), in its (2)A(1g) ground state is inferred from photodissociation of cold Si(2)H(6)(+)-Ar(n) complexes (n = 1, 2). Vibrational analysis is consistent with a D(3d) symmetric structure of H(3)SiSiH(3)(+) generated by ionization from the bonding σ(SiSi) orbital. Structural, vibrational, and electronic properties of Si(2)H(6)((+)) and Si(2)H(6)(+)-Ar(1,2) are determined at the MP2/aug-cc-pVTZ and B3LYP/aug-cc-pVTZ levels. Ar ligands bind weakly at the C(3) axis on opposite sides to Si(2)H(6)(+) with only a minor impact on the Si(2)H(6)(+) properties. The calculations reveal a low-energy H(2)SiHSiH(3)(+) isomer with C(s) symmetry and a Si-H-Si bridge, which is only ~15 kJ mol(-1) above the D(3d) structure. PMID:23325390

  6. Investigation on the Interactions of NiCR and NiCR-2H with DNA

    PubMed Central

    Chitranshi, Priyanka; Chen, Chang-Nan; Jones, Patrick R.; Faridi, Jesika S.; Xue, Liang

    2010-01-01

    We report here a biophysical and biochemical approach to determine the differences in interactions of NiCR and NiCR-2H with DNA. Our goal is to determine whether such interactions are responsible for the recently observed differences in their cytotoxicity toward MCF-7 cancer cells. Viscosity measurement and fluorescence displacement titration indicated that both NiCR and NiCR-2H bind weakly to duplex DNA in the grooves. The coordination of NiCR-2H with the N-7 of 2′-deoxyguanosine 5′-monophosphate (5′-dGMP) is stronger than that of NiCR as determined by 1H NMR. NiCR-2H, like NiCR, can selectively oxidize guanines present in distinctive DNA structures (e.g., bulges), and notably, NiCR-2H oxidizes guanines more efficiently than NiCR. In addition, UV and 1H NMR studies revealed that NiCR is oxidized into NiCR-2H in the presence of KHSO5 at low molar ratios with respect to NiCR (≤4). PMID:20671951

  7. Identification of Metastasis-Associated Metabolic Profiles of Tumors by (1)H-HR-MAS-MRS.

    PubMed

    Gorad, Saurabh S; Ellingsen, Christine; Bathen, Tone F; Mathiesen, Berit S; Moestue, Siver A; Rofstad, Einar K

    2015-10-01

    Tumors develop an abnormal microenvironment during growth, and similar to the metastatic phenotype, the metabolic phenotype of cancer cells is tightly linked to characteristics of the tumor microenvironment (TME). In this study, we explored relationships between metabolic profile, metastatic propensity, and hypoxia in experimental tumors in an attempt to identify metastasis-associated metabolic profiles. Two human melanoma xenograft lines (A-07, R-18) showing different TMEs were used as cancer models. Metabolic profile was assessed by proton high resolution magic angle spinning magnetic resonance spectroscopy ((1)H-HR-MAS-MRS). Tumor hypoxia was detected in immunostained histological preparations by using pimonidazole as a hypoxia marker. Twenty-four samples from 10 A-07 tumors and 28 samples from 10 R-18 tumors were analyzed. Metastasis was associated with hypoxia in both A-07 and R-18 tumors, and (1)H-HR-MAS-MRS discriminated between tissue samples with and tissue samples without hypoxic regions in both models, primarily because hypoxia was associated with high lactate resonance peaks in A-07 tumors and with low lactate resonance peaks in R-18 tumors. Similarly, metastatic and non-metastatic R-18 tumors showed significantly different metabolic profiles, but not metastatic and non-metastatic A-07 tumors, probably because some samples from the metastatic A-07 tumors were derived from tumor regions without hypoxic tissue. This study suggests that (1)H-HR-MAS-MRS may be a valuable tool for evaluating the role of hypoxia and lactate in tumor metastasis as well as for identification of metastasis-associated metabolic profiles. PMID:26585232

  8. (11)B MAS NMR and First-Principles Study of the [OBO3] Pyramids in Borates.

    PubMed

    Zhou, Bing; Sun, Wei; Zhao, Biao-Chun; Mi, Jin-Xiao; Laskowski, Robert; Terskikh, Victor; Zhang, Xi; Yang, Lingyun; Botis, Sanda M; Sherriff, Barbara L; Pan, Yuanming

    2016-03-01

    Borates are built from the [Bϕ3] planar triangles and the [Bϕ4] tetrahedral groups, where ϕ denotes O or OH. However, the [Bϕ4] groups in some borates are highly distorted to include three normal B-O bonds and one anomalously long B-O bond and, therefore, are best described as the [OBO3] pyramids. Four synthetic borates of the boracite-type structures (Mg3B7O13Br, Cu3B7O13Br, Zn3B7O13Cl, and Mg3B7O13Cl) containing a range of [OBO3] pyramids were investigated by multifield (7.05, 14.1, and 21.1 T) (11)B magic-angle spinning nuclear magnetic resonance (MAS NMR), triple quantum (3Q) MAS NMR experiments, as well as density functional theory calculations. The high-resolution (11)B MAS NMR spectra supported by theoretical predictions show that the [OBO3] pyramids are characterized by isotropic chemical shifts δiso((11)B) from 1.4(1) to 4.9(1) ppm and nuclear quadrupole parameters CQ((11)B) up to 1.3(1) MHz, both significantly different from those of the [BO4] and [BO3] groups in borates. These δiso((11)B) and CQ((11)B) values indicate that the [OBO3] pyramids represent an intermediate state between the [BO4] tetrahedra and [BO3] triangles and demonstrate that the (11)B NMR parameters of four-coordinate boron oxyanions are sensitive to local structural environments. The orientation of the calculated unique electronic field gradient tensor element Vzz of the [OBO3] pyramids is aligned approximately along the direction of the anomalously long B-O bond, corresponding to B-2pz with the lowest electron density. PMID:26914372

  9. Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials

    NASA Astrophysics Data System (ADS)

    Paik, Younkee

    Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and deuterium-intercalated pyrolusite and ramsdellite were detected by NMR, for the first time, and their locations and motions in the structures were analyzed by applying variable temperature NMR techniques. Discharge mechanisms of EMD in alkaline (aqueous) electrolytes were studied, in conjunction with step potential electrochemical spectroscopic (SPECS) method, and five distinctive discharge processes were proposed. EMD is usually heat-treated at about 300--400°C to remove water to be used in lithium batteries. Details of the effects of heat-treatment, such as structural and compositional changes as a function of heat-treatment temperature, were studied by a combination of MAS NMR, XRD, and thermogravimetric analysis. Lithium local environments in heat-treated EMD (HEMD) that were discharged in lithium cells, were described in terms of related environments found in model compounds pyrolusite and ramsdellite where specific Li + sites were detected by MAS NMR and the hyperfine shift scale method of Grey et al. Acid-leaching of Li2MnO3 represents an approach for synthesizing new or modified manganese oxide electrode materials for lithium rechargeable batteries. Progressive removal of lithium from specific crystallographic sites, followed by a gradual change of the crystal structure, was monitored by a combination of NMR and XRD techniques.

  10. The Novel 10-Item Asthma Prediction Tool: External Validation in the German MAS Birth Cohort

    PubMed Central

    Grabenhenrich, Linus B.; Reich, Andreas; Fischer, Felix; Zepp, Fred; Forster, Johannes; Schuster, Antje; Bauer, Carl-Peter; Bergmann, Renate L.; Bergmann, Karl E.; Wahn, Ulrich; Keil, Thomas; Lau, Susanne

    2014-01-01

    Background A novel non-invasive asthma prediction tool from the Leicester Cohort, UK, forecasts asthma at age 8 years based on 10 predictors assessed in early childhood, including current respiratory symptoms, eczema, and parental history of asthma. Objective We aimed to externally validate the proposed asthma prediction method in a German birth cohort. Methods The MAS-90 study (Multicentre Allergy Study) recorded details on allergic diseases prospectively in about yearly follow-up assessments up to age 20 years in a cohort of 1,314 children born 1990. We replicated the scoring method from the Leicester cohort and assessed prediction, performance and discrimination. The primary outcome was defined as the combination of parent-reported wheeze and asthma drugs (both in last 12 months) at age 8. Sensitivity analyses assessed model performance for outcomes related to asthma up to age 20 years. Results For 140 children parents reported current wheeze or cough at age 3 years. Score distribution and frequencies of later asthma resembled the Leicester cohort: 9% vs. 16% (MAS-90 vs. Leicester) of children at low risk at 3 years had asthma at 8 years, at medium risk 45% vs. 48%. Performance of the asthma prediction tool in the MAS-90 cohort was similar (Brier score 0.22 vs. 0.23) and discrimination slightly better than in the original cohort (area under the curve, AUC 0.83 vs. 0.78). Prediction and discrimination were robust against changes of inclusion criteria, scoring and outcome definitions. The secondary outcome ‘physicians’ diagnosed asthma at 20 years' showed the highest discrimination (AUC 0.89). Conclusion The novel asthma prediction tool from the Leicester cohort, UK, performed well in another population, a German birth cohort, supporting its use and further development as a simple aid to predict asthma risk in clinical settings. PMID:25536057

  11. Direct ab initio study of the C6H6 + CH3/C2H5 = C6H5 + CH4/C2H6 reactions

    NASA Astrophysics Data System (ADS)

    Mai, Tam V.-T.; Ratkiewicz, Artur; Duong, Minh v.; Huynh, Lam K.

    2016-02-01

    A kinetic study of the reactions C6H6 + CH3/C2H5 = C6H5 + CH4/C2H6 was carried out in the temperature range of 300-2500 K using high levels of electronic structure theory, namely, CCSD(T)/CBS//BH&HLYP/cc-pVDZ, and canonical variational transition state theory (CVT) with corrections for small curvature tunneling (SCT) and hindered internal rotation (HIR) treatments. It is found that variational effect is not important and both SCT and HIR corrections noticeably affect the rate constants. Being in good agreement with literature data, the calculated results provide solid basis information for the investigation of the polyaromatic hydrocarbon (PAH) + alkyl radical reaction, an important class in combustion and soot formation.

  12. MAS Equipped with Ant Colony Applied into Dynamic Job Shop Scheduling

    NASA Astrophysics Data System (ADS)

    Kang, Kai; Zhang, Ren Feng; Yang, Yan Qing

    This paper presents a methodology adopting the new structure of MAS(multi-agent system) equipped with ACO(ant colony optimization) algorithm for a better schedule in dynamic job shop. In consideration of the dynamic events in the job shop arriving indefinitely schedules are generated based on tasks with ant colony algorithm. Meanwhile, the global objective is taken into account for the best solution in the actual manufacturing environment. The methodology is tested on a simulated job shop to determine the impact with the new structure.

  13. MAS: Malware Analysis System Based on Hardware-Assisted Virtualization Technology

    NASA Astrophysics Data System (ADS)

    Kim, Taehyoung; Kim, Inhyuk; Min, Changwoo; Eom, Young Ik

    There are many analysis techniques in order to analyze malicious codes. However, recently malicious codes often evade detection using stealthy obfuscation techniques, and attack computing systems. We propose an enhanced dynamic binary instrumentation using hardware-assisted virtualization technology. As a machine-level analyzer, our system can be isolated from almost the whole threats of malware, and provides single step analysis environment. Proposed system also supports rapid system call analysis environment. We implement our malware analysis system (referred as MAS) on the KVM hypervisor with Intel VT-x virtualization support. Our experiments with benchmarks show that the proposed system provides efficient analysis environment with low overhead.

  14. Recent Results from the MicroMAS Global Environmental MonitoringNanosatellite Mission

    NASA Astrophysics Data System (ADS)

    Blackwell, W. J.; Cahoy, K.

    2014-12-01

    The Micro-sized Microwave Atmospheric Satellite (MicroMAS) is a dual-spinning 3U CubeSat equipped with apassive microwave radiometer that observes in nine channels near the 118.75-GHz oxygen absorption line.MicroMAS is designed to observe convective thunderstorms, tropical cyclones, and hurricanes from a midinclinationorbit. The MicroMAS flight unit was developed by MIT Lincoln Laboratory and the MIT Space SystemsLaboratory and was launched to the International Space Station on July 13, 2014, and scheduled for an earlySeptember deployment for a ~90-day mission. The payload is housed in the "lower" 1U of the dual-spinning 3UCubeSat and mechanically rotated approximately once per second as the spacecraft orbits the Earth, resulting in across-track scanned beam with a full-width half-max (FWHM) beamwidth of 2.4 degrees and an approximately 17-km diameter footprint at nadir incidence from a nominal altitude of 400 km. The relatively low cost of MicroMASenables the deployment of a constellation of sensors, spaced equally around several orbit planes. A small fleet ofMicroMAS systems could yield high-resolution global temperature and water vapor profiles, as well as cloudmicrophysical and precipitation parameters.Significant advancements were made in the Assembly, Integration, and Test phase of the project developmentlifecycle. The flight software and communications architecture was refined and tested in relevant lab facilities. Thepower subsystem was modified to include additional required inhibits for the ISS launch. Hardware in the loop testsas well as simulations of the attitude determination and control system (ADCS) were performed to validate theunique dual-spinning, local vertical, local horizontal (LVLH) stabilized flight design. ADCS algorithms were testedon a 3-axis air bearing and custom rig inside a 3-axis programmable Helmholtz cage. Finally, the integratedspacecraft underwent a series of environmental tests in order to verify the results of thermal modeling

  15. Muscle attachment site (MAS) patterns for species determination in five species of Sarcophaga (Diptera: Sarcophagidae).

    PubMed

    Niederegger, Senta; Szpila, Krzysztof; Mall, Gita

    2016-01-01

    To further establish species determination using the muscle attachment site (MAS) pattern method, third instar larvae of five forensically important species of Sarcophaga Meigen were investigated: Sarcophaga argyrostoma (Robineau-Desvoidy), Sarcophaga caerulescens Zetterstedt, Sarcophaga melanura Meigen, Sarcophaga albiceps Meigen and Sarcophaga similis Meade. As in the previously investigated Calliphoridae, patterns were found to be species specific. The main feature of the Sarcophaga patterns is the divided central horizontal row of segment four. A genus pattern was established to be used as base for comparison in further species determination. PMID:26391172

  16. Laboratory studies of 2H evaporator scale dissolution in dilute nitric acid

    SciTech Connect

    Oji, L.

    2014-09-23

    The rate of 2H evaporator scale solids dissolution in dilute nitric acid has been experimentally evaluated under laboratory conditions in the SRNL shielded cells. The 2H scale sample used for the dissolution study came from the bottom of the evaporator cone section and the wall section of the evaporator cone. The accumulation rate of aluminum and silicon, assumed to be the two principal elemental constituents of the 2H evaporator scale aluminosilicate mineral, were monitored in solution. Aluminum and silicon concentration changes, with heating time at a constant oven temperature of 90 deg C, were used to ascertain the extent of dissolution of the 2H evaporator scale mineral. The 2H evaporator scale solids, assumed to be composed of mostly aluminosilicate mineral, readily dissolves in 1.5 and 1.25 M dilute nitric acid solutions yielding principal elemental components of aluminum and silicon in solution. The 2H scale dissolution rate constant, based on aluminum accumulation in 1.5 and 1.25 M dilute nitric acid solution are, respectively, 9.21E-04 ± 6.39E-04 min{sup -1} and 1.07E-03 ± 7.51E-05 min{sup -1}. Silicon accumulation rate in solution does track the aluminum accumulation profile during the first few minutes of scale dissolution. It however diverges towards the end of the scale dissolution. This divergence therefore means the aluminum-to-silicon ratio in the first phase of the scale dissolution (non-steady state conditions) is different from the ratio towards the end of the scale dissolution. Possible causes of this change in silicon accumulation in solution as the scale dissolution progresses may include silicon precipitation from solution or the 2H evaporator scale is a heterogeneous mixture of aluminosilicate minerals with several impurities. The average half-life for the decomposition of the 2H evaporator scale mineral in 1.5 M nitric acid is 12.5 hours, while the half-life for the decomposition of the 2H evaporator scale in 1.25 M nitric acid is 10

  17. {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions at sub-coulomb energies

    SciTech Connect

    Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Sparta, R.; Aliotta, M.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Mrazek, J.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

    2012-11-20

    The {sup 2}H({sup 3}He,p{sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n{sup 3}He){sup 1}H processes have been measured in quasi free kinematics to investigate for the first time the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions by means of the Trojan Horse Method. The {sup 3}He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

  18. Immobilized MAS1 lipase showed high esterification activity in the production of triacylglycerols with n-3 polyunsaturated fatty acids.

    PubMed

    Wang, Xiumei; Li, Daoming; Qu, Man; Durrani, Rabia; Yang, Bo; Wang, Yonghua

    2017-02-01

    Immobilization of lipase MAS1 from marine Streptomyces sp. strain W007 and its application in catalyzing esterification of n-3 polyunsaturated fatty acids (PUFA) with glycerol were investigated. The resin XAD1180 was selected as a suitable support for the immobilization of lipase MAS1, and its absorption ability was 75mg/g (lipase/resin ratio) with initial buffer pH value of 8.0. The thermal stability of immobilized MAS1 was improved significantly compared with that of the free lipase. Immobilized MAS1 had no regiospecificity in the hydrolysis of triolein. The highest esterification degree (99.31%) and TAG content (92.26%) by immobilized MAS1-catalyzed esterification were achieved under the optimized conditions, which were significantly better than those (82.16% and 47.26%, respectively) by Novozym 435. More than 92% n-3 PUFA was incorporated into TAG that had similar fatty acids composition to the substrate (n-3 PUFA). The immobilized MAS1 exhibited 50% of its initial activity after being used for five cycles. PMID:27596418

  19. Quantitative C2H2 measurements in sooty flames using mid-infrared polarization spectroscopy

    NASA Astrophysics Data System (ADS)

    Sun, Z. W.; Li, Z. S.; Li, B.; Alwahabi, Z. T.; Aldén, M.

    2010-10-01

    Quantitative measurements of acetylene (C2H2) molecules as a combustion intermediate species in a series of rich premixed C2H4/air flames were non-intrusively performed, spatially resolved, using mid-infrared polarization spectroscopy (IRPS), by probing its fundamental ro-vibrational transitions. The flat sooty C2H4/air premixed flames with different equivalence ratios varying from 1.25 to 2.50 were produced on a 6 cm diameter porous-plug McKenna type burner at atmospheric pressure, and all measurements were performed at a height of 8.5 mm above the burner surface. IRPS excitation scans in different flame conditions were performed and rotational line-resolved spectra were recorded. Spectral features of acetylene molecules were readily recognized in the spectral ranges selected, with special attention to avoid the spectral interference from the large amount of coexisting hot water and other hydrocarbon molecules. On-line calibration of the optical system was performed in a laminar C2H2/N2 gas flow at ambient conditions. Using the flame temperatures measured by coherent anti-Stokes Raman spectroscopy in a previous work, C2H2 mole fractions in different flames were evaluated with collision effects and spectral overlap between molecular line and laser source being analyzed and taken into account. C2H2 IRPS signals in two different buffering gases, N2 and CO2, had been investigated in a tube furnace in order to estimate the spectral overlap coefficients and collision effects at different temperatures. The soot-volume fractions (SVF) in the studied flames were measured using a He-Ne laser-extinction method, and no obvious degrading of the IRPS technique due to the sooty environment has been observed in the flame with SVF up to ˜2×10-7. With the increase of flame equivalence ratios not only the SVF but also the C2H2 mole fractions increased.

  20. Potential energy surface for C2H4I2+ dissociation including spin-orbit effects

    SciTech Connect

    Siebert, Matthew R.; Aquino, Adelia J.; De Jong, Wibe A.; Granucci, Giovanni; Hase, William L.

    2012-10-24

    Previous experiments [Baer, et al. J. Phys. Chem. A 116, 2833 (2012)] have studied the dissociation of 1,2-diiodoethane radical cation (C2H4I2+•) and found a one-dimensional distribution of translational energy; an odd finding considering most product relative translational energy distributions are two-dimensional. The goal of this study is to obtain an accurate understanding of the potential energy surface (PES) topology for the unimolecular decomposition reaction C2H4I2+• - C2H4I+ + I•. This is done through comparison of many single-reference electronic structure methods, coupled-cluster single point (energy) calculations, and multi-reference calculations used to quantify spin-orbit (SO) coupling effects. We find that the structure of the C2H4I2+• reactant has a substantial effect on the role of SO coupling on the reaction energy. Both the BHandH and MP2 theories with an ECP/6-31++G** basis set, and without SO coupling corrections, provide accurate models for the reaction energetics. MP2 theory gives an unsymmetric structure with different C-I bond lengths, resulting in a SO energy for C2H4I2+• similar to that for the product I-atom and a negligible SO correction to the reaction energy. In contrast, DFT gives a symmetric structure for C2H4I2+•, similar to that of the neutral C2H4I2 parent, resulting in a substantial SO correction and increasing the reaction energy by 6.0-6.5 kcal/mol. Also, we find that for this system single point energy calculations are inaccurate, since a small change in geometry can lead to a large change in energy.

  1. Increasing brain angiotensin converting enzyme 2 activity decreases anxiety-like behavior in male mice by activating central Mas receptors.

    PubMed

    Wang, Lei; de Kloet, Annette D; Pati, Dipanwita; Hiller, Helmut; Smith, Justin A; Pioquinto, David J; Ludin, Jacob A; Oh, S Paul; Katovich, Michael J; Frazier, Charles J; Raizada, Mohan K; Krause, Eric G

    2016-06-01

    Over-activation of the brain renin-angiotensin system (RAS) has been implicated in the etiology of anxiety disorders. Angiotensin converting enzyme 2 (ACE2) inhibits RAS activity by converting angiotensin-II, the effector peptide of RAS, to angiotensin-(1-7), which activates the Mas receptor (MasR). Whether increasing brain ACE2 activity reduces anxiety by stimulating central MasR is unknown. To test the hypothesis that increasing brain ACE2 activity reduces anxiety-like behavior via central MasR stimulation, we generated male mice overexpressing ACE2 (ACE2 KI mice) and wild type littermate controls (WT). ACE2 KI mice explored the open arms of the elevated plus maze (EPM) significantly more than WT, suggesting increasing ACE2 activity is anxiolytic. Central delivery of diminazene aceturate, an ACE2 activator, to C57BL/6 mice also reduced anxiety-like behavior in the EPM, but centrally administering ACE2 KI mice A-779, a MasR antagonist, abolished their anxiolytic phenotype, suggesting that ACE2 reduces anxiety-like behavior by activating central MasR. To identify the brain circuits mediating these effects, we measured Fos, a marker of neuronal activation, subsequent to EPM exposure and found that ACE2 KI mice had decreased Fos in the bed nucleus of stria terminalis but had increased Fos in the basolateral amygdala (BLA). Within the BLA, we determined that ∼62% of GABAergic neurons contained MasR mRNA and expression of MasR mRNA was upregulated by ACE2 overexpression, suggesting that ACE2 may influence GABA neurotransmission within the BLA via MasR activation. Indeed, ACE2 overexpression was associated with increased frequency of spontaneous inhibitory postsynaptic currents (indicative of presynaptic release of GABA) onto BLA pyramidal neurons and central infusion of A-779 eliminated this effect. Collectively, these results suggest that ACE2 may reduce anxiety-like behavior by activating central MasR that facilitate GABA release onto pyramidal neurons within the

  2. Protective effects of Cornus mas fruit extract on carbon tetrachloride induced nephrotoxicity in rats

    PubMed Central

    Es.Haghi, M.; Dehghan, G.; Banihabib, N.; Zare, S.; Mikaili, P.; Panahi, F.

    2014-01-01

    Oxidative damage is implicated in the pathogenesis of kidney injury. Cornus mas is used for in renal aliments traditionally in Iran. The present study was aimed to investigate the antioxidant activity of C. mas fruit extract (CMFE) on carbon tetrachloride (CCl4) treated oxidative stress in Wistar albino rats. Forty two male albino rats were divided into seven groups. Group I served as a sham; Group II served as a normal control; Group III served as a toxic control, with CCl4 (1 ml/kg body weight; 80% in olive oil); Groups IV and V received CMFE at doses of 300 and 700 mg/kg before CCl4 injection; Groups VI and VII received extract at same doses orally at 2, 6, 12, 24 and 48 h after CCl4 intoxication. CCl4 injection produced a significant rise in serum markers of oxidative stress and lipid peroxidation product malondialdehyde along with the reduction of antioxidant enzymes such as superoxide dismuta, catalase and glutathion peroxidase. Serum creatinine, urea and uric acid concentrations were increased whereas level of protein and albumin were reduced. Treatment of rats with different doses of fruit extract (300 and 700 mg/kg) significantly (P < 0.05) ameliorated the alterations induced with CCl4 in lipid peroxidation, antioxidant defenses, biochemical and renal lesions. Based on these results, we conclude that CMFE protects kidney from oxidative stress induced by CCl4. PMID:25249718

  3. Ammonia Vapor Removal by Cu3(BTC)2 and Its Characterization by MAS NMR

    PubMed Central

    Peterson, Gregory W.; Wagner, George W.; Balboa, Alex; Mahle, John; Sewell, Tara; Karwacki, Christopher J.

    2009-01-01

    Adsorption equilibria and NMR experiments were performed to study the adsorption and interactions of ammonia with metal-organic framework (MOF) HKUST-1, or Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate). Ammonia capacities determined from chemical breakthrough measurements show significantly higher uptake capacities than from adsorption alone, suggesting a stronger interaction involving a potential reaction with the Cu3(BTC)2 framework. Indeed, 1H MAS NMR reveals that a major disruption of the relatively simple spectrum of Cu3(BTC)2 occurs to generate a composite spectrum consistent with Cu(OH)2 and (NH4)3BTC species under humid conditions—the anticipated products of a copper(II) carboxylate reacted with limited ammonia. These species are not detected under dry conditions; however, reaction stoichiometry combined with XRD results suggests the partial formation of an indeterminate diammine copper (II) complex with some residual Cu3(BTC)2 structure retained. Cu(II)-induced paramagnetic shifts exhibited by various species in 1H and 13C MAS NMR spectra are consistent with model compounds and previous literature. Although results show extensive ammonia capacity of Cu3(BTC)2, much of the capacity is due to reaction with the structure itself, causing a permanent loss in porosity and structural integrity. PMID:20161144

  4. Molecular orientational dynamics in C70S48: Investigation by 13C MAS NMR

    NASA Astrophysics Data System (ADS)

    Grell, A.-S.; Talyzin, A.; Pirotte, P.; Masin, F.

    2001-11-01

    At room temperature the MAS 13C NMR spectrum of C70S48 is identical to that of pure C70 above 323 K, except that the 13C line is shifted by 1.7 ppm compared to that of pure C70. From these results, we deduce that our system is mainly of the van der Waals type. A simulation of the low speed MAS spectrum shows that C70 molecules in C70S48 undergo a uniaxial rotation as in pure C70. This new result contradicts what had been previously published. The chemical shift of the 13C line does not vary with temperature, however the rotation of C70 slows down as the temperature is decreased and stops at ca. 150 K. Moreover the 13C spin-lattice relaxation time, T1, can be described by a single correlation time that follows an Arrhenius law with a 900 K activation energy. By NMR no phase transition is observed at 245 K contrary to dielectric relaxation measurements.

  5. Structural analysis of molybdo-zinc-phosphate glasses: Neutron scattering, FTIR, Raman scattering, MAS NMR studies

    NASA Astrophysics Data System (ADS)

    Renuka, C.; Shinde, A. B.; Krishna, P. S. R.; Reddy, C. Narayana

    2016-08-01

    Vitreous samples were prepared in the xMoO3-17ZnO-(83-x) NaPO3 with 35 ≥ x ≥ 55 glass forming system by energy efficient microwave heating method. Structural evolution of the vitreous network was monitored as a function of composition by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), Raman scattering, Magic Angle Spin Nuclear magnetic resonance (MAS NMR) and Neutron scattering. Addition of MoO3 to the ZnO-NaPO3 glass leads to a pronounced increase in glass transition temperature (Tg) suggesting a significant increase in network connectivity and strength. In order to analyze FTIR and Raman scattering, a simple structural model is presented to rationalize the experimental observations. A number of structural units are formed due to network modification, and the resulting glass may be characterized by a network polyhedral with different numbers of unshared corners. 31P MAS NMR confirms a clear distinction between structural species having 3, 2, 1, 0 bridging oxygens (BOs). Further, Neutron scattering studies were used to probe the structure of these glasses. The result suggests that all the investigated glasses have structures based on chains of four coordinated phosphate and six coordinated molybdate units, besides, two different lengths of P-O bonds in tetrahedral phosphate units that are assigned to bonds of the P-atom with terminal and bridging oxygen atoms.

  6. Synthesis, spectral characterization and larvicidal activity of acridin-1(2H)-one analogues

    NASA Astrophysics Data System (ADS)

    Subashini, R.; Bharathi, A.; Roopan, Selvaraj Mohana; Rajakumar, G.; Abdul Rahuman, A.; Gullanki, Pavan Kumar

    Acridin-1(2H)-one analogue of 7-chloro-3,4-dihydro-9-phenyl-2-[(pyridine-2yl) methylene] acridin-1(2H)-one, 5 was prepared by using 7-chloro-3,4-dihydro-9-phenylacridin-1(2H)-one, 3 and picolinaldehyde, 4 in the presence of KOH at room temperature. These compounds were characterized by analytical and spectral analyses. The purpose of the present study was to assess the efficacy of larvicidal and repellent activity of synthesized 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues such as compounds 3 and 5 against the early fourth instar larvae of filariasis vector, Culex quinquefasciatus and Japanese encephalitis vector, Culex gelidus (Diptera: Culicidae). The compound exhibited high larvicidal effects at 50 mg/L against both the mosquitoes with LC50 values of 25.02 mg/L (r2 = 0.998) and 26.40 mg/L (r2 = 0.988) against C. quinquefasciatus and C. gelidus, respectively. The 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues that are reported for the first time to our best of knowledge can be better explored for the control of mosquito population. This is an ideal ecofriendly approach for the control of Japanese encephalitis vectors, C. quinquefasciatus and C. gelidus.

  7. Drivers of δ2H variations in an idealized extratropical cyclone

    NASA Astrophysics Data System (ADS)

    Dütsch, Marina; Pfahl, Stephan; Wernli, Heini

    2016-05-01

    Numerical model simulations of stable water isotopes help to improve our understanding of the complex processes driving isotopic variability in atmospheric moisture. We use the isotope-enabled Consortium for Small-Scale Modelling (COSMO) model to study the governing mechanisms of δ2H variations in an idealized extratropical cyclone. A set of experiments with differing initial conditions of δ2H in vapor and partly deactivated isotopic fractionation allows us to quantify the relative roles of cloud fractionation and vertical and horizontal advection for the simulated δ2H signals associated with the cyclone and fronts. Horizontal transport determines the large-scale pattern of δ2H in both vapor and precipitation, while fractionation and vertical transport are more important on a smaller scale, near the fronts. During the passage of the cold front fractionation leads to a V-shaped trend of δ2H in precipitation and vapor, which is, for vapor, superimposed on a gradual decrease caused by the arrival of colder air masses.

  8. Blood brain barrier breakdown was found in non-infarcted area after 2-h MCAO.

    PubMed

    Wang, Xiaona; Liu, Yushan; Sun, Yanyun; Liu, Wenlan; Jin, Xinchun

    2016-04-15

    The blood brain barrier (BBB) could be damaged within the thrombolytic time window and is considered to be a precursor to hemorrhagic transformation during reperfusion. Although we have recently reported the association between BBB damage and tissue injury within the thrombolytic time window, our knowledge about this early BBB damage is limited. In this study, rats were subjected to 2-h middle cerebral artery occlusion (MCAO) followed by 10 min reperfusion with Evan's blue as a tracer to detect BBB damage. Rat brain was sliced into 10 consecutive sections and with TTC staining, a macro and full view of the spatial distribution of BBB damage and tissue injury could be clearly seen in the same group of animals. After 2-h MCAO, tissue injury started from 2nd slice and the BBB leakage started from the 5th slice, of note, there is no colocalization between BBB damage and tissue injury. Fluoro Jade B was employed to explore the localization of neuronal degeneration, and our results showed that 2-h MCAO produced greater number of positive cells in ischemic cortex and dorsal striatum than other areas. More important, 2-h MCAO induced occludin but not claudin-5 degradation in the ischemic hemisphere and pretreatment with MMP inhibitor GM6001 significantly reduced occludin degradation as well as BBB damage detected by IgG leakage. Taken together, our findings demonstrated a "mismatch" between ischemic tissue injury and BBB leakage and a differential degradation of occludin and claudin-5 by MMP-2 after 2-h MCAO. PMID:27000223

  9. 2H transmit-receive NMR probes for magnetic field monitoring in MRI.

    PubMed

    Sipilä, Pekka; Greding, Sebastian; Wachutka, Gerhard; Wiesinger, Florian

    2011-05-01

    Measuring image encoding fields in real time and applying the information in postprocessing offer improved image quality for MRI, particularly for applications that are intrinsically sensitive to gradient imperfections. For this task, a stand-alone magnetometer system based on multiple (2)H transmit-receive NMR probes has been developed. The conceptual advantages of changing to (2)H NMR probes for (1)H magnetic field monitoring are elucidated here, and the practical design of the probes is described. In comparison to previous (1)H NMR probe-based designs, (2)H probes are perfectly decoupled from standard (1)H imaging. Utilization of RF shielding or other nonoptimal decoupling schemes is therefore not needed. Probes based on (2)H nuclei are also more easily miniaturized for high-resolution imaging. This is particularly important for diffusion tensor and phase-contrast imaging, which rely on strong motion-sensitizing gradients. The presented (2)H NMR probes have been shown to fulfill the requirements for accurate (1)H imaging down to image resolutions of 0.2 mm. Using susceptibility matching techniques, the probe's B(0) inhomogeneity-induced signal dephasing is reduced and monitoring periods beyond 200 msec are achieved. The benefit of real time magnetic field monitoring is highlighted for phase-contrast and non-Cartesian multishot imaging. PMID:21254204

  10. Prediction of the existence of the N2H- molecular anion

    NASA Astrophysics Data System (ADS)

    Lique, François; Halvick, Philippe; Stoecklin, Thierry; Hochlaf, Majdi

    2012-06-01

    We predict the existence of the N2H- anion from first principle calculations. We present the three-dimensional potential energy surface and the bound states of the N2H-/D- van der Waals anion. The electronic calculations were performed using state-of-the-art ab initio methods and the nuclear motions were solved using a quantum close-coupling scattering theory. A T-shaped equilibrium structure was found, with a well depth of 349.1 cm-1, where 18 bound states have been located for N2H- and 25 for N2D- for total angular momentum J = 0. We also present the absorption spectra of the N2H- complex. This anion could be formed after low energy collisions between N2 and H- through radiative association. The importance of this prediction in astrophysics and the possible use of N2H- as a tracer of N2 and H- in the interstellar medium is discussed.

  11. Inhibition of Mas G-protein signaling improves coronary blood flow, reduces myocardial infarct size, and provides long-term cardioprotection.

    PubMed

    Zhang, Tong; Li, Zhuangjie; Dang, Huong; Chen, Ruoping; Liaw, Chen; Tran, Thuy-Anh; Boatman, P Douglas; Connolly, Daniel T; Adams, John W

    2012-01-01

    The Mas receptor is a class I G-protein-coupled receptor that is expressed in brain, testis, heart, and kidney. The intracellular signaling pathways activated downstream of Mas are still largely unknown. In the present study, we examined the expression pattern and signaling of Mas in the heart and assessed the participation of Mas in cardiac ischemia-reperfusion injury. Mas mRNA and protein were present in all chambers of human hearts, with cardiomyocytes and coronary arteries being sites of enriched expression. Expression of Mas in either HEK293 cells or cardiac myocytes resulted in constitutive coupling to the G(q) protein, which in turn activated phospholipase C and caused inositol phosphate accumulation. To generate chemical tools for use in probing the function of Mas, we performed a library screen and chemistry optimization program to identify potent and selective nonpeptide agonists and inverse agonists. Mas agonists activated G(q) signaling in a dose-dependent manner and reduced coronary blood flow in isolated mouse and rat hearts. Conversely, treatment of isolated rat hearts with Mas inverse agonists improved coronary flow, reduced arrhythmias, and provided cardioprotection from ischemia-reperfusion injury, an effect that was due, at least in part, to decreased cardiomyocyte apoptosis. Participation of Mas in ischemia-reperfusion injury was confirmed in Mas knockout mice, which had reduced infarct size relative to mice with normal Mas expression. These results suggest that activation of Mas during myocardial infarction contributes to ischemia-reperfusion injury and further suggest that inhibition of Mas-G(q) signaling may provide a new therapeutic strategy directed at cardioprotection. PMID:22003054

  12. Hydrogenation-induced atomic stripes on the 2 H -MoS2 surface

    NASA Astrophysics Data System (ADS)

    Han, Sang Wook; Yun, Won Seok; Lee, J. D.; Hwang, Y. H.; Baik, J.; Shin, H. J.; Lee, Wang G.; Park, Young S.; Kim, Kwang S.

    2015-12-01

    We report that the hydrogenation of a single crystal 2 H -MoS2 induces a novel-intermediate phase between 2H and 1T phases on its surface, i.e., the large-area, uniform, robust, and surface array of atomic stripes through the intralayer atomic-plane gliding. The total energy calculations confirm that the hydrogenation-induced atomic stripes are energetically most stable on the MoS2 surface between the semiconducting 2H and metallic 1T phase. Furthermore, the electronic states associated with the hydrogen ions, which is bonded to sulfur anions on both sides of the MoS2 surface layer, appear in the vicinity of the Fermi level (EF) and reduces the band gap. This is promising in developing the monolayer-based field-effect transistor or vanishing the Schottky barrier for practical applications.

  13. Commonality of TRIM32 mutation in causing sarcotubular myopathy and LGMD2H.

    PubMed

    Schoser, Benedikt G H; Frosk, Patrick; Engel, Andrew G; Klutzny, Ursula; Lochmüller, Hanns; Wrogemann, Klaus

    2005-04-01

    Sarcotubular myopathy (OMIM 268950) is a rare autosomal recessive myopathy first described in two Hutterite brothers from South Dakota and in two non-Hutterite brothers from Germany. We report that sarcotubular myopathy (STM) is caused by mutation in TRIM32, the gene encoding the tripartite motif-containing protein 32. TRIM32 was found to be the gene mutated in limb girdle muscular dystrophy type 2H (LGMD2H [OMIM 254110]), a disorder that has been confined to the Hutterite population. The TRIM32 mutation found in the STM patients is identical to the causative mutation for LGMD2H (D487N), Haplotype analysis shows that the disease chromosomes share common ancestry. PMID:15786463

  14. Photodetectors and birefringence in ZnP2-С2h5 crystals

    NASA Astrophysics Data System (ADS)

    Stamov, I. G.; Syrbu, N. N.; Dorogan, A. V.

    2013-03-01

    The spectral dependences of refractive indexes no(n⊥), ne(n||) and Δn=no(n⊥)-ne(n||) were studied in ZnP2-C2h5 crystals. The intersection of no(n⊥) and ne(n||) was found for λ0=0.906 μm. The crystal possesses positive dispersion Δn=no(n⊥)-ne(n||) in the region where λ>λ0, and a negative dispersion is observed in the region where λ<λ0. The electrical, spectral and azimuth characteristics of monolith n-р- and Ме-n-р-ZnP2C2h5 and discrete ZnP2-C2h5-ZnP2-D48 structures were studied, and a prognosis was made on the usage perspective of these devices.

  15. Analysis Of 2H-Evaporator Scale Pot Bottom Sample [HTF-13-11-28H

    SciTech Connect

    Oji, L. N.

    2013-07-15

    Savannah River Remediation (SRR) is planning to remove a buildup of sodium aluminosilicate scale from the 2H-evaporator pot by loading and soaking the pot with heated 1.5 M nitric acid solution. Sampling and analysis of the scale material from the 2H evaporator has been performed so that the evaporator can be chemically cleaned beginning July of 2013. Historically, since the operation of the Defense Waste Processing Facility (DWPF), silicon in the DWPF recycle stream combines with aluminum in the typical tank farm supernate to form sodium aluminosilicate scale mineral deposits in the 2H-evaporator pot and gravity drain line. The 2H-evaporator scale samples analyzed by Savannah River National Laboratory (SRNL) came from the bottom cone sections of the 2H-evaporator pot. The sample holder from the 2H-evaporator wall was virtually empty and was not included in the analysis. It is worth noting that after the delivery of these 2H-evaporator scale samples to SRNL for the analyses, the plant customer determined that the 2H evaporator could be operated for additional period prior to requiring cleaning. Therefore, there was no need for expedited sample analysis as was presented in the Technical Task Request. However, a second set of 2H evaporator scale samples were expected in May of 2013, which would need expedited sample analysis. X-ray diffraction analysis (XRD) confirmed the bottom cone section sample from the 2H-evaporator pot consisted of nitrated cancrinite, (a crystalline sodium aluminosilicate solid), clarkeite and uranium oxide. There were also mercury compound XRD peaks which could not be matched and further X-ray fluorescence (XRF) analysis of the sample confirmed the existence of elemental mercury or mercuric oxide. On ''as received'' basis, the scale contained an average of 7.09E+00 wt % total uranium (n = 3; st.dev. = 8.31E-01 wt %) with a U-235 enrichment of 5.80E-01 % (n = 3; st.dev. = 3.96E-02 %). The measured U-238 concentration was 7.05E+00 wt % (n=3, st

  16. Natural 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol®).

    PubMed

    Schwab, Wilfried

    2013-01-01

    4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF, furaneol®) and its methyl ether 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMMF) are import aroma chemicals and are considered key flavor compounds in many fruit. Due to their attractive sensory properties they are highly appreciated by the food industry. In fruits 2,5-dimethyl-3(2H)-furanones are synthesized by a series of enzymatic steps whereas HDMF is also a product of the Maillard reaction. Numerous methods for the synthetic preparation of these compounds have been published and are applied by industry, but for the development of a biotechnological process the knowledge and availability of biosynthetic enzymes are required. During the last years substantial progress has been made in the elucidation of the biological pathway leading to HDMF and DMMF. This review summarizes the latest advances in this field. PMID:23765232

  17. Theoretical study of the C-H bond dissociation energy of C2H

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1990-01-01

    A theoretical study of the convergence of the C-H bond dissociation energy D(0) in C2H with respect to both the one- and n-particle spaces is presented. The calculated C-H bond energies of C2H2 and C2H4, which are in excellent agreement with experiment, are used for calibration. The best estimate for D(0) of 112.4 + or - 2.0 kcal/mol is slightly below the recent experimental value of 116.3 + or - 2.6 kcal/mol, but substantially above a previous theoretical estimate of 102 kcal/mol. The remaining discrepancy with experiment may reflect primarily the uncertainty in the experimental D(0) value of C2 required in the analysis.

  18. Detection of C2H4 Neptune from ISO/PHT-S Observations

    NASA Technical Reports Server (NTRS)

    Schulz, B.; Encrenaz, Th.; Bezard, B.; Romani, P. N.; Lellouch, E.; Atreya, S. K.

    1999-01-01

    The 6-12 micrometer spectrum of Neptune has been recorded with the PHT-S instrument of the Infrared Space Observatory (ISO) at a resolution of 0.095 micrometer. In addition to the emissions of CH4, CH3D and C2H6 previously identified, the spectrum shows the first firm identification of ethylene C2H4. The inferred column density above the 0.2-mbar level is in the range (1.1 - 3) x 10(exp 14) molecules/cm. To produce this low amount, previous photochemical models invoked rapid mixing between the source and sink regions of C2H4. We show that this requirement can be relaxed if recent laboratory measurements of CH4 photolysis branching ratios at Lyman alpha are used.

  19. N2H(+) in the Orion ambient ridge - Cloud clumping versus rotation

    NASA Technical Reports Server (NTRS)

    Womack, Maria; Ziurys, L. M.; Sage, L. J.

    1993-01-01

    The IRAM 30-m telescope is used to obtain spectra of the J = 1 yields 0 transition of N2H(+) over a 2 x 2 arcsec area toward the Orion-KL/IRc2 star-forming region with 26-arcsec angular resolution. The N2H(+) emission, which exclusively traces the ridge gas, exhibits multiple radial velocities which appear to arise from the presence of at least four clouds of quiescent material. It is argued that the velocity structure of N2H(+) does not uniformly change across OMC-1 and, consequently, is inconsistent with the presence of large-scale differential rotation of the extended ridge along the SW-NE axis about IRc2. The coincidence of the two larger clouds with star-forming activity in Orion-KL suggests that either the quiescent gas is being pushed apart or that the star formation may have been triggered by a cloud-cloud interaction.

  20. Online high-precision delta(2)H and delta(18)O analysis in water by pyrolysis.

    PubMed

    Lu, Feng H

    2009-10-01

    A method for online simultaneous delta(2)H and delta(18)O analysis in water by high-temperature conversion is presented. Water is injected by using a syringe into a high-temperature carbon reactor and converted into H(2) and CO, which are separated by gas chromatography (GC) and carried by helium to the isotope ratio mass spectrometer for hydrogen and oxygen isotope analysis. A series of experiments was conducted to evaluate several issues such as sample size, temperature and memory effects. The delta(2)H and delta(18)O values in multiple water standards changed consistently as the reactor temperature increased from 1150 to 1480 degrees C. The delta(18)O in water can be measured at a lower temperature (e.g. 1150 degrees C) although the precision was relatively poor at temperatures <1300 degrees C. Memory effects exist for delta(2)H and delta(18)O between two waters, and can be reduced (to <1%) with proper measures. The injection of different amounts of water may affect the isotope ratio results. For example, in contrast to small injections (100 nL or less) from small syringes (e.g. 1.2 microL), large injections (1 microL or more) from larger syringes (e.g. 10 microL) with dilution produced asymmetric peaks and shifts of isotope ratios, e.g. 4 per thousand for delta(2)H and 0.4 per thousand for delta(18)O, probably resulting from isotope fractionation during dilution via the ConFlo interface. This method can be used to analyze nanoliter samples of water (e.g. 30 nL) with good precision of 0.5 per thousand for delta(2)H and 0.1 per thousand for delta(18)O. This is important for geosciences; for instance, fluid inclusions in ancient minerals may be analyzed for delta(2)H and delta(18)O to help understand the formation environments. PMID:19714707

  1. Lipid Bilayer-Bound Conformation of an Integral Membrane Beta Barrel Protein by Multidimensional MAS NMR

    PubMed Central

    Eddy, Matthew T.; Su, Yongchao; Silvers, Robert; Andreas, Loren; Clark, Lindsay; Wagner, Gerhard; Pintacuda, Guido; Emsley, Lyndon; Griffin, Robert G.

    2015-01-01

    The human voltage dependent anion channel 1 (VDAC) is a 32 kDa β-barrel integral membrane protein that controls the transport of ions across the outer mitochondrial membrane. Despite the determination of VDAC solution and diffraction structures, a structural basis for the mechanism of its function is not yet fully understood. Biophysical studies suggest VDAC requires a lipid bilayer to achieve full function, motivating the need for atomic resolution structural information of VDAC in a membrane environment. Here we report an essential step toward that goal: extensive assignments of backbone and side chain resonances for VDAC in DMPC lipid bilayers via magic angle spinning nuclear magnetic resonance (MAS NMR). VDAC reconstituted into DMPC lipid bilayers spontaneously forms 2-dimensional lipid crystals, showing remarkable spectral resolution (0.5–0.3 ppm for 13C line width and less than 0.5 ppm 15N line widths at 750 MHz). In addition to the benefits of working in a lipid bilayer, several distinct advantages are observed with the lipid crystalline preparation. First, the strong signals and sharp line widths facilitated extensive NMR resonance assignments for an integral membrane β-barrel protein in lipid bilayers by MAS NMR. Second, a large number of residues in loop regions were readily observed and assigned, which can be challenging in detergent-solubilized membrane proteins where loop regions are often not detected due to line broadening from conformational exchange. Third, complete backbone and side chain chemical shift assignments could be obtained for the first 25 residues, which comprise the functionally important N-terminus. The reported assignments allow us to compare predicted torsion angles for VDAC prepared in DMPC 2D lipid crystals, DMPC liposomes, and LDAO-solubilized samples to address the possible effects of the membrane mimetic environment on the conformation of the protein. Concluding, we discuss the strengths and weaknesses of the reported

  2. Lipid bilayer-bound conformation of an integral membrane beta barrel protein by multidimensional MAS NMR.

    PubMed

    Eddy, Matthew T; Su, Yongchao; Silvers, Robert; Andreas, Loren; Clark, Lindsay; Wagner, Gerhard; Pintacuda, Guido; Emsley, Lyndon; Griffin, Robert G

    2015-04-01

    The human voltage dependent anion channel 1 (VDAC) is a 32 kDa β-barrel integral membrane protein that controls the transport of ions across the outer mitochondrial membrane. Despite the determination of VDAC solution and diffraction structures, a structural basis for the mechanism of its function is not yet fully understood. Biophysical studies suggest VDAC requires a lipid bilayer to achieve full function, motivating the need for atomic resolution structural information of VDAC in a membrane environment. Here we report an essential step toward that goal: extensive assignments of backbone and side chain resonances for VDAC in DMPC lipid bilayers via magic angle spinning nuclear magnetic resonance (MAS NMR). VDAC reconstituted into DMPC lipid bilayers spontaneously forms two-dimensional lipid crystals, showing remarkable spectral resolution (0.5-0.3 ppm for (13)C line widths and <0.5 ppm (15)N line widths at 750 MHz). In addition to the benefits of working in a lipid bilayer, several distinct advantages are observed with the lipid crystalline preparation. First, the strong signals and sharp line widths facilitated extensive NMR resonance assignments for an integral membrane β-barrel protein in lipid bilayers by MAS NMR. Second, a large number of residues in loop regions were readily observed and assigned, which can be challenging in detergent-solubilized membrane proteins where loop regions are often not detected due to line broadening from conformational exchange. Third, complete backbone and side chain chemical shift assignments could be obtained for the first 25 residues, which comprise the functionally important N-terminus. The reported assignments allow us to compare predicted torsion angles for VDAC prepared in DMPC 2D lipid crystals, DMPC liposomes, and LDAO-solubilized samples to address the possible effects of the membrane mimetic environment on the conformation of the protein. Concluding, we discuss the strengths and weaknesses of the reported

  3. Analytical potential energy surface for O + C2H2 system

    NASA Astrophysics Data System (ADS)

    Garashchuk, Sophya; Rassolov, Vitaly A.; Braams, Bastiaan J.

    2013-11-01

    Full-dimensional analytical potential energy surfaces (PESs) for the O(1P) + C2H2 and O(3P) + C2H2 reactions are presented. The PESs are constructed by fitting thousands of ab initio data points using permutationally invariant polynomials [5]. Electronic structure data are obtained within the restricted coupled cluster theory with single and double excitations with perturbative triple corrections and correlation consistent basis set of triple-ζ with diffuse functions. Motivated by experiments, formation of DOCC and cyclic DCCO at collision energies of 2.5-4 eV is examined using quasi-classical trajectory dynamics on the triplet surface.

  4. Effects of deuterium oxide on cell growth and vesicle speed in RBL-2H3 cells

    PubMed Central

    Triplett, Ashley R.

    2014-01-01

    For the first time we show the effects of deuterium oxide on cell growth and vesicle transport in rat basophilic leukemia (RBL-2H3) cells. RBL-2H3 cells cultured with 15 moles/L deuterium showed decreased cell growth which was attributed to cells not doubling their DNA content. Experimental observations also showed an increase in vesicle speed for cells cultured in deuterium oxide. This increase in vesicle speed was not observed in deuterium oxide cultures treated with a microtubule-destabilizing drug, suggesting that deuterium oxide affects microtubule-dependent vesicle transport. PMID:25237603

  5. Implications of C2H photochemistry on the modeling of C2 distributions in comets

    NASA Technical Reports Server (NTRS)

    Jackson, William M.; Bao, Yihan; Urdahl, Randall S.

    1991-01-01

    Laboratory studies of the secondary photolysis of the C2H radical are summarized and used to explain some discrepancies between models of C2 emission in comets. These studies show that several states of the C2 radicals produced in the photolysis of C2H2 at 193 nm have bimodal rotational distributions when plotted as a Boltzmann diagram. They also establish that the C2 radicals are formed with varying degrees of vibrational excitation, so that if they are formed in a similar manner in comets, the C2 radicals must start out with this initial vibrational excitation.

  6. Low-temperature solid-state phase transformations in 2H silicon carbide

    NASA Technical Reports Server (NTRS)

    Will, H. A.; Powell, J. A.

    1972-01-01

    Single crystals of 2H SiC were observed to undergo phase transformations at temperatures as low as 400 C. Some 2H crystals transformed to a structure with one-dimensional disorder along the crystal c axis. Others transformed to a faulted cubic/6H structure. The transformation is time and temperature dependent and is greatly enhanced by dislocations. Observations indicate that the transformation takes place by means of a slip process perpendicular to the c axis. Cubic SiC crystals were observed to undergo a solid state transformation above 1400 C.

  7. First-principles characterization of potassium intercalation in the hexagonal 2H-MoS2

    SciTech Connect

    Andersen, Amity; Kathmann, Shawn M.; Lilga, Michael A.; Albrecht, Karl O.; Hallen, Richard T.; Mei, Donghai

    2012-01-12

    Periodic density functional theory calculations were performed to study the structural and electronic properties of potassium intercalated into hexagonal MoS{sub 2} (2H-MoS{sub 2}). Metallic potassium (K) atoms are incrementally loaded in the hexagonal sites of the interstitial spaces between MoS2 sheets of the 2H-MoS{sub 2} bulk structure generating 2H-KxMoS2 (0.125 {<=} x {<=} 1.0) structures. To accommodate the potassium atoms, the interstitial spacing c parameter in the 2H-MoS{sub 2} bulk expands from 12.816 {angstrom} in 2H-MoS{sub 2} to 16.086 {angstrom} in 2H-K{sub 0.125}MoS{sub 2}. The second lowest potassium loading concentration (K{sub 0.25}MoS{sub 2}) results in the largest interstitial spacing expansion (to c = 16.726 {angstrom}). Our calculations show that there is a small gradual contraction of the interstitial spacing as the potassium loading increases with c = 14.839 {angstrom} for KMoS{sub 2}. This interstitial contraction is correlated with an in-plane expansion of the MoS{sub 2} sheets, which is in good agreement with experimental X-ray diffraction (XRD) measurements. The electronic analysis shows that potassium readily donates its 4s electron to the conduction band of the 2H-K{sub x}MoS{sub 2}, and is largely ionic in character. As a result of the electron donation, the 2H-K{sub x}MoS{sub 2} system changes from a semiconductor to a more metallic system with increasing potassium intercalation. For loadings 0.25 {<=} x {<=} 0.625, triangular Mo-Mo-Mo moieties are prominent and tend to form rhombitrihexagonal motifs. Intercalation of H{sub 2}O molecules that solvate the K atoms is likely to occur in catalytic conditions. The inclusion of two H{sub 2}O molecules per K atom in the K{sub 0.25}MoS{sub 2} structure shows good agreement with XRD measurements.

  8. Calculation of the Aluminosilicate Half-Life Formation Time in the 2H Evaporator

    SciTech Connect

    Fondeur, F.F.

    2000-09-21

    The 2H Evaporator contains large quantities of aluminosilicate solids deposited on internal fixtures. The proposed cleaning operations will dissolve the solids in nitric acid. Operations will then neutralize the waste prior to transfer to a waste tank. Combining recent calculations of heat transfer for the 2H Evaporator cleaning operations and laboratory experiments for dissolution of solid samples from the pot, the authors estimated the re-formation rate for aluminosilicates during cooling. The results indicate a half-life formation of 17 hours when evaporator solution cools from 60 degrees C and 9 hours when cooled from 90 degrees C.

  9. High-resolution absorption cross sections of C2H6 at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Hargreaves, Robert J.; Buzan, Eric; Dulick, Michael; Bernath, Peter F.

    2015-11-01

    Infrared absorption cross sections near 3.3 μm have been obtained for ethane, C2H6. These were acquired at elevated temperatures (up to 773 K) using a Fourier transform infrared spectrometer and tube furnace with a resolution of 0.005 cm-1. The integrated absorption was calibrated using composite infrared spectra taken from the Pacific Northwest National Laboratory (PNNL). These new measurements are the first high-resolution infrared C2H6 cross sections at elevated temperatures.

  10. Infrared intensities and optical constants of crystalline C 2H 4 and C 2D 4

    NASA Astrophysics Data System (ADS)

    Zhao, G.; Ospina, M. J.; Khanna, R. K.

    Infrared absorption spectra of several thin films of C 2H 4 and C 2D 4 at ˜55 K were investigated at ˜0.6 cm -1 resolution. The integrated band intensities of the infrared active fundamental modes were obtained by a linear fit of the integrated absorbances vs film thickness. An iterative Kramers—Kronig analysis of the absorption data was carried out to obtain the complex refractive indices of crystalline C 2H 4 and C 2D 4 in the regions of absorption bands.

  11. Role of Mas receptor in renal blood flow response to angiotensin-(1-7) in ovariectomized estradiol treated rats

    PubMed Central

    Saberi, Shadan; Dehghani, Aghdas; Nematbakhsh, Mehdi

    2016-01-01

    The angiotensin 1-7 (Ang 1-7), is abundantly produced in kidneys and antagonizes the function of angiotensin II through Mas receptor (MasR) or other unknown mechanisms. In the current study, the role of MasR and steroid hormone estrogen on renal blood flow response to Ang 1-7 administration was investigated in ovariectomized (OV) female rats. OV female Wistar-rats received estradiol (500 μg/kg/week) or vehicle for two weeks. In the day of the experiment, the animals were anesthetized, cannulated, and the responses including mean arterial pressure, renal blood flow (RBF), and renal vascular resistance at the constant level of renal perfusion pressure to graded infusion of Ang 1-7 at 0, 100 and 300 ng/kg/min were determined in OV and OV estradiol-treated (OVE) rats, treated with vehicle or MasR antagonist; A779. RBF response to Ang 1-7 infusion increased dose-dependently in vehicle (Pdose<0.001) and A779-treated (Pdose<0.01) animals. However, when MasR was blocked, the RBF response to Ang 1-7 significantly increased in OV animals compared with OVE rats (P<0.05). When estradiol was limited by ovariectomy, A779 increased RBF response to Ang 1-7 administration, while this response was attenuated in OVE animals. PMID:27051434

  12. Role of Mas receptor in renal blood flow response to angiotensin-(1-7) in ovariectomized estradiol treated rats.

    PubMed

    Saberi, Shadan; Dehghani, Aghdas; Nematbakhsh, Mehdi

    2016-01-01

    The angiotensin 1-7 (Ang 1-7), is abundantly produced in kidneys and antagonizes the function of angiotensin II through Mas receptor (MasR) or other unknown mechanisms. In the current study, the role of MasR and steroid hormone estrogen on renal blood flow response to Ang 1-7 administration was investigated in ovariectomized (OV) female rats. OV female Wistar-rats received estradiol (500 μg/kg/week) or vehicle for two weeks. In the day of the experiment, the animals were anesthetized, cannulated, and the responses including mean arterial pressure, renal blood flow (RBF), and renal vascular resistance at the constant level of renal perfusion pressure to graded infusion of Ang 1-7 at 0, 100 and 300 ng/kg/min were determined in OV and OV estradiol-treated (OVE) rats, treated with vehicle or MasR antagonist; A779. RBF response to Ang 1-7 infusion increased dose-dependently in vehicle (Pdose <0.001) and A779-treated (Pdose <0.01) animals. However, when MasR was blocked, the RBF response to Ang 1-7 significantly increased in OV animals compared with OVE rats (P<0.05). When estradiol was limited by ovariectomy, A779 increased RBF response to Ang 1-7 administration, while this response was attenuated in OVE animals. PMID:27051434

  13. Studies of minute quantities of natural abundance molecules using 2D heteronuclear correlation spectroscopy under 100kHz MAS

    SciTech Connect

    Nishiyama, Y.; Kobayashi, T.; Malon, M.; Singappuli-Arachchige, D.; Slowing, I. I.; Pruski, M.

    2015-02-16

    Two-dimensional 1H{13C} heteronuclear correlation solid-state NMR spectra of naturally abundant solid materials are presented, acquired using the 0.75-mm magic angle spinning (MAS) probe at spinning rates up to 100 kHz. In spite of the miniscule sample volume (290 nL), high-quality HSQC-type spectra of bulk samples as well as surface-bound molecules can be obtained within hours of experimental time. The experiments are compared with those carried out at 40 kHz MAS using a 1.6-mm probe, which offered higher overall sensitivity due to a larger rotor volume. The benefits of ultrafast MAS in such experiments include superior resolution in 1H dimension without resorting to 1H–1H homonuclear RF decoupling, easy optimization, and applicability to mass-limited samples. As a result, the HMQC spectra of surface-bound species can be also acquired under 100 kHz MAS, although the dephasing of transverse magnetization has significant effect on the efficiency transfer under MAS alone.

  14. Studies of minute quantities of natural abundance molecules using 2D heteronuclear correlation spectroscopy under 100kHz MAS

    DOE PAGESBeta

    Nishiyama, Y.; Kobayashi, T.; Malon, M.; Singappuli-Arachchige, D.; Slowing, I. I.; Pruski, M.

    2015-02-16

    Two-dimensional 1H{13C} heteronuclear correlation solid-state NMR spectra of naturally abundant solid materials are presented, acquired using the 0.75-mm magic angle spinning (MAS) probe at spinning rates up to 100 kHz. In spite of the miniscule sample volume (290 nL), high-quality HSQC-type spectra of bulk samples as well as surface-bound molecules can be obtained within hours of experimental time. The experiments are compared with those carried out at 40 kHz MAS using a 1.6-mm probe, which offered higher overall sensitivity due to a larger rotor volume. The benefits of ultrafast MAS in such experiments include superior resolution in 1H dimensionmore » without resorting to 1H–1H homonuclear RF decoupling, easy optimization, and applicability to mass-limited samples. As a result, the HMQC spectra of surface-bound species can be also acquired under 100 kHz MAS, although the dephasing of transverse magnetization has significant effect on the efficiency transfer under MAS alone.« less

  15. Unfolding the Quantum Nature of Proton Bound Symmetric Dimers of (MeOH)2H+ and (Me2O)2H+: a Theoretical Study

    NASA Astrophysics Data System (ADS)

    Tan, Jake Acedera; Kuo, Jer-Lai

    2014-06-01

    A proton under a tug of war between two competing Lewis bases is a common motif in biological systems and proton transfer processes. Over the past decades, model compounds for such motifs can be prepared by delicate stoichiometric control of salt solutions. Unfortunately, condensed phase studies, which aims to identify the key vibrational signatures are complicated to analyze. As a result, gas-phase studies do provide promising insights on the behavior of the shared proton. This study attempts to understand the quantum nature of the shared proton under theoretical paradigms. Proton bound symmetric dimers of (MeOH)2H+ and (Me2O)2H+ are chosen as the model compounds. The simulation is performed using Density Functional Theory (DFT) at the B3LYP level with 6-311+G(d,p) as the basis set. It was found out that stretching mode of shared proton couples with several other normal modes and its corresponding oscillator strength do distribute to other normal modes. J.R. Roscioli, L.R. McCunn and M.A. Johnson. Science 2007, 316, 249 T.E. DeCoursey. Physiol. Rev., 2003, 83, 475 E.S. Stoyanov. Psys. Chem. Phys., 2000,2,1137

  16. Applications of the massively parallel machine, the MasPar MP-1, to Earth sciences

    NASA Technical Reports Server (NTRS)

    Fischer, James R.; Strong, James P.; Dorband, John E.; Tilton, James C.

    1991-01-01

    The computational workload of upcoming NASA science missions, especially the ground data processing for the Earth Observing System, is projected to be quite large (in the 50 to 100 gigaFLOPS range) and corespondingly very expensive to perform using conventional supercomputer systems. High performance, general purpose massively parallel computer systems such as the MasPar MP-1 are being investigated by NASA as a more cost effective alternative. Massively parallel systems are targeted for accelerated development and maturation by NASA's upcoming five-year High Performance Computing and Communications Program. A summary of the broad range of applications currently running on the MP-1 at NASA/Goddard are presented in this paper along with descriptions of the parallel algorithmic techniques employed in five applications that have bearing on Earth sciences.

  17. High-resolution multiple quantum MAS NMR spectroscopy of half-integer quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Wu, Gang; Rovnyank, David; Sun, Boqin; Griffin, Robert G.

    1996-02-01

    We demonstrate the utility of a two-pulse sequence in obtaining high-resolution solid state NMR spectra of half-integer quadrupolar nuclei with magic-angle-spinning (MAS). The experiment, which utilizes multiple/single-quantum correlation, was first described in a different form by Frydman and Harwood [J. Am. Chem. Soc. 117 (1995) 5367] and yields high-resolution isotropic NMR spectra where shifts are determined by the sum of resonance offset (chemical shift) and second-order quadrupolar effects. The two-pulse sequence described here is shown to provide a higher and more uniform excitation of multiple-quantum coherence than the three-pulse sequence used previously.

  18. Molecular degradation of ancient documents revealed by 1H HR-MAS NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Corsaro, Carmelo; Mallamace, Domenico; Łojewska, Joanna; Mallamace, Francesco; Pietronero, Luciano; Missori, Mauro

    2013-10-01

    For centuries mankind has stored its knowledge on paper, a remarkable biomaterial made of natural cellulose fibers. However, spontaneous cellulose degradation phenomena weaken and discolorate paper over time. The detailed knowledge of products arising from cellulose degradation is essential in understanding deterioration pathways and in improving durability of cultural heritage. In this study, for the first time, products of cellulose degradation were individually detected in solid paper samples by means of an extremely powerful proton HR-MAS NMR set-up, in combination to a wise use of both ancient and, as reference, artificially aged paper samples. Carboxylic acids, in addition to more complex dicarboxylic and hydroxy-carboxylic acids, were found in all samples studied. Since these products can catalyze further degradation, their knowledge is fundamental to improve conservation strategies of historical documents. Furthermore, the identification of compounds used in ancient production techniques, also suggests for artifacts dating, authentication and provenance.

  19. Regulation of alveolar epithelial cell survival by the ACE-2/angiotensin 1-7/Mas axis.

    PubMed

    Uhal, Bruce D; Li, Xiaopeng; Xue, Anita; Gao, Xu; Abdul-Hafez, Amal

    2011-09-01

    Earlier work from this laboratory demonstrated that apoptosis of alveolar epithelial cells (AECs) requires autocrine generation of angiotensin (ANG) II. More recent studies showed that angiotensin converting enzyme-2 (ACE-2), which degrades ANGII to form ANG1-7, is protective but severely downregulated in human and experimental lung fibrosis. Here it was theorized that ACE-2 and its product ANG1-7 might therefore regulate AEC apoptosis. To evaluate this hypothesis, the AEC cell line MLE-12 and primary cultures of rat AECs were exposed to the profibrotic apoptosis inducers ANGII or bleomycin (Bleo). Markers of apoptosis (caspase-9 or -3 activation and nuclear fragmentation), steady-state ANGII and ANG1-7, and JNK phosphorylation were measured thereafter. In the absence of Bleo, inhibition of ACE-2 by small interfering RNA or by a competitive inhibitor (DX600 peptide) caused a reciprocal increase in autocrine ANGII and corresponding decrease in ANG1-7 in cell culture media (both P < 0.05) and, moreover, induced AEC apoptosis. At baseline (without inhibitor), ANG1-7 in culture media was 10-fold higher than ANGII (P < 0.01). Addition of purified ANGII or bleomycin-induced caspase activation, nuclear fragmentation, and JNK phosphorylation in cultured AECs. However, preincubation with ANG1-7 (0.1 μM) prevented JNK phosphorylation and apoptosis. Moreover, pretreatment with A779, a specific blocker of the ANG1-7 receptor mas, prevented ANG1-7 blockade of JNK phosphorylation, caspase activation, and nuclear fragmentation. These data demonstrate that ACE-2 regulates AEC survival by balancing the proapoptotic ANGII and its antiapoptotic degradation product ANG1-7. They also suggest that ANG1-7 inhibits AEC apoptosis through the ANG1-7 receptor mas. PMID:21665960

  20. Paramagnet induced signal quenching in MAS-DNP experiments in frozen homogeneous solutions

    NASA Astrophysics Data System (ADS)

    Corzilius, Björn; Andreas, Loren B.; Smith, Albert A.; Ni, Qing Zhe; Griffin, Robert G.

    2014-03-01

    The effects of nuclear signal quenching induced by the presence of a paramagnetic polarizing agent are documented for conditions used in magic angle spinning (MAS)-dynamic nuclear polarization (DNP) experiments on homogeneous solutions. In particular, we present a detailed analysis of three time constants: (1) the longitudinal build-up time constant TB for 1H; (2) the rotating frame relaxation time constant T1ρ for 1H and 13C and (3) T2 of 13C, the transverse relaxation time constant in the laboratory frame. These relaxation times were measured during microwave irradiation at a magnetic field of 5 T (140 GHz) as a function of the concentration of four polarizing agents: TOTAPOL, 4-amino-TEMPO, trityl (OX063), and Gd-DOTA and are compared to those obtained for a sample lacking paramagnetic doping. We also report the EPR relaxation time constants T1S and T2S, the DNP enhancements, ε, and the parameter E, defined below, which measures the sensitivity enhancement for the four polarizing agents as a function of the electron concentration. We observe substantial intensity losses (paramagnetic quenching) with all of the polarizing agents due to broadening mechanisms and cross relaxation during MAS. In particular, the monoradical trityl and biradical TOTAPOL induce ∼40% and 50% loss of signal intensity. In contrast there is little suppression of signal intensity in static samples containing these paramagnetic species. Despite the losses due to quenching, we find that all of the polarizing agents provide substantial gains in signal intensity with DNP, and in particular that the net enhancement is optimal for biradicals that operate with the cross effect. We discuss the possibility that much of this polarization loss can be regained with the development of instrumentation and methods to perform electron decoupling.

  1. Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy

    PubMed Central

    Debelouchina, Galia T.; Bayro, Marvin J.; Fitzpatrick, Anthony W.; Ladizhansky, Vladimir; Colvin, Michael T.; Caporini, Marc A.; Jaroniec, Christopher P.; Bajaj, Vikram S.; Rosay, Melanie; MacPhee, Cait E.; Vendruscolo, Michele; Maas, Werner E.; Dobson, Christopher M.; Griffin, Robert G.

    2014-01-01

    Protein magic angle spinning (MAS) NMR spectroscopy has generated structural models of several amyloid fibril systems, thus providing valuable information regarding the forces and interactions that confer the extraordinary stability of the amyloid architecture. Despite these advances, however, obtaining atomic resolution information describing the higher levels of structural organization within the fibrils remains a significant challenge. Here, we detail MAS NMR experiments and sample labeling schemes designed specifically to probe such higher order amyloid structure and we have applied them to the fibrils formed by an eleven-residue segment of the amyloidogenic protein transthyretin (TTR(105-115)). These experiments have allowed us to define unambiguously not only the arrangement of the peptide β-strands into β-sheets but also the β-sheet interfaces within each protofilament, and in addition to identify the nature of the protofilament-to-protofilament contacts that lead to the formation of the complete fibril. Our efforts have resulted in 111 quantitative distance and torsion angle restraints (10 per residue) that describe the various levels of structure organization. The experiments benefited extensively from the use of dynamic nuclear polarization (DNP), which in some cases allowed us to shorten the data acquisition time from days to hours and to improve significantly the signal-to-noise ratios of the spectra. The β-sheet interface and protofilament interactions identified here revealed local variations in the structure that result in multiple peaks for the exposed N- and C-termini of the peptide and in inhomogeneous line-broadening for the side-chains buried within the interior of the fibrils. PMID:24304221

  2. Not all M&As are alike--and that matters.

    PubMed

    Bower, J L

    2001-03-01

    Despite all that's been written about mergers and acquisitions, even the experts know surprisingly little about them. The author recently headed up a year-long study sponsored by Harvard Business School on the subject of M&A activity. In-depth findings will emerge over the next few years, but the research has already revealed some interesting results. Most intriguing is the notion that, although academics, consultants, and businesspeople lump M&As together, they represent very different strategic activities. Acquisitions occur for the following reasons: to deal with overcapacity through consolidation in mature industries; to roll up competitors in geographically fragmented industries; to extend into new products and markets; as a substitute for R&D; and to exploit eroding industry boundaries by inventing an industry. The different strategic intents present distinct integration challenges. For instance, if you acquire a company because your industry has excess capacity, you have to determine which plants to shut down and which people to let go. If, on the other hand, you buy a company because it has developed an important technology, your challenge is to keep the acquisition's best engineers from jumping ship. These scenarios require the acquiring company to engage in nearly opposite managerial behaviors. The author explores each type of M&A--its strategic intent and the integration challenges created by that intent. He underscores the importance of the acquiring company's assessment of the acquired group's culture. Depending on the type of M&A, approaches to the culture in place must vary, as will the level to which culture interferes with integration. He draws from the experiences of such companies as Cisco, Viacom, and BancOne to exemplify the different kinds of M&As. PMID:11246927

  3. Sensitivity enhancement using paramagnetic relaxation in MAS solid-state NMR of perdeuterated proteins

    NASA Astrophysics Data System (ADS)

    Linser, Rasmus; Chevelkov, Veniamin; Diehl, Anne; Reif, Bernd

    2007-12-01

    Previously, Ishii et al., could show that chelated paramagnetic ions can be employed to significantly decrease the recycle delay of a MAS solid-state NMR experiment [N.P. Wickramasinghe, M. Kotecha, A. Samoson, J. Past, Y. Ishii, Sensitivity enhancement in C-13 solid-state NMR of protein microcrystals by use of paramagnetic metal ions for optimizing H-1 T-1 relaxation, J. Magn. Reson. 184 (2007) 350-356]. Application of the method is limited to very robust samples, for which sample stability is not compromised by RF induced heating. In addition, probe integrity might be perturbed in standard MAS PRE experiments due to the use of very short duty cycles. We show that these deleterious effects can be avoided if perdeuterated proteins are employed that have been re-crystallized from D 2O:H 2O = 9:1 containing buffer solutions. The experiments are demonstrated using the SH3 domain of chicken α-spectrin as a model system. The labeling scheme allows to record proton detected 1H, 15N correlation spectra with very high resolution in the absence of heteronuclear dipolar decoupling. Cu-edta as a doping reagent yields a reduction of the recycle delay by up to a factor of 15. In particular, we find that the 1H T1 for the bulk H N magnetization is reduced from 4.4 s to 0.3 s if the Cu-edta concentration is increased from 0 mM to 250 mM. Possible perturbations like chemical shift changes or line broadening due to the paramagnetic chelate complex are minimal. No degradation of our samples was observed in the course of the experiments.

  4. Induced Signal Quenching in MAS-DNP Experiments in Homogeneous Solutions

    PubMed Central

    Corzilius, Björn; Andreas, Loren B.; Smith, Albert A.; Ni, Qing Zhe; Griffin, Robert G.

    2014-01-01

    The effects of nuclear signal quenching induced by the presence of a paramagnetic polarizing agent are documented for conditions used in magic angle spinning (MAS)-dynamic nuclear polarization (DNP) experiments on homogeneous solutions. In particular, we present a detailed analysis of three time constants: (1) the longitudinal build-up time constant TB for 1H; (2) the rotating frame relaxation time constant T1ρ for 1H and 13C and (3) T2 of 13C, the transverse relaxation time constant in the laboratory frame. These relaxation times were measured during microwave irradiation at a magnetic field of 5 T (140 GHz) as a function of the concentration of four polarizing agents: TOTAPOL, 4-amino-TEMPO, trityl (OX063), and Gd-DOTA and are compared to those obtained for a sample lacking paramagnetic doping. We also report the EPR relaxation time constants T1S and T2S, the DNP enhancements, ε, and the parameter E, defined below, which measures the sensitivity enhancement for the four polarizing agents as a function of the electron concentration. We observe substantial intensity losses (paramagnetic quenching) with all of the polarizing agents due to broadening mechanisms and cross relaxation during MAS. In particular, the monoradical trityl and biradical TOTAPOL induce ~40 and 50% loss of signal intensity. In contrast there is little suppression of signal intensity in static samples containing these paramagnetic species. Despite the losses due to quenching, we find that all of the polarizing agents provide substantial gains in signal intensity, and in particular that the net enhancement is optimal for biradicals that operate with the cross effect. We discuss the possibility that much of this polarization loss can be regained with the development of instrumentation and methods to perform electron decoupling. PMID:24394190

  5. Dynamic Nuclear Polarization Enhanced MAS NMR Spectroscopy for Structural Analysis of HIV-1 Protein Assemblies.

    PubMed

    Gupta, Rupal; Lu, Manman; Hou, Guangjin; Caporini, Marc A; Rosay, Melanie; Maas, Werner; Struppe, Jochem; Suiter, Christopher; Ahn, Jinwoo; Byeon, In-Ja L; Franks, W Trent; Orwick-Rydmark, Marcella; Bertarello, Andrea; Oschkinat, Hartmut; Lesage, Anne; Pintacuda, Guido; Gronenborn, Angela M; Polenova, Tatyana

    2016-01-21

    Mature infectious HIV-1 virions contain conical capsids composed of CA protein, generated by the proteolytic cleavage cascade of the Gag polyprotein, termed maturation. The mechanism of capsid core formation through the maturation process remains poorly understood. We present DNP-enhanced MAS NMR studies of tubular assemblies of CA and Gag CA-SP1 maturation intermediate and report 20-64-fold sensitivity enhancements due to DNP at 14.1 T. These sensitivity enhancements enabled direct observation of spacer peptide 1 (SP1) resonances in CA-SP1 by dipolar-based correlation experiments, unequivocally indicating that the SP1 peptide is unstructured in assembled CA-SP1 at cryogenic temperatures, corroborating our earlier results. Furthermore, the dependence of DNP enhancements and spectral resolution on magnetic field strength (9.4-18.8 T) and temperature (109-180 K) was investigated. Our results suggest that DNP-based measurements could potentially provide residue-specific dynamics information by allowing for the extraction of the temperature dependence of the anisotropic tensorial or relaxation parameters. With DNP, we were able to detect multiple well-resolved isoleucine side-chain conformers; unique intermolecular correlations across two CA molecules; and functionally relevant conformationally disordered states such as the 14-residue SP1 peptide, none of which are visible at ambient temperatures. The detection of isolated conformers and intermolecular correlations can provide crucial constraints for structure determination of these assemblies. Overall, our results establish DNP-based MAS NMR spectroscopy as an excellent tool for the characterization of HIV-1 assemblies. PMID:26709853

  6. An improved technique for the 2H/1H analysis of urines from diabetic volunteers

    USGS Publications Warehouse

    Coplen, T.B.; Harper, I.T.

    1994-01-01

    The H2-H2O ambient-temperature equilibration technique for the determination of 2H/1H ratios in urinary waters from diabetic subjects provides improved accuracy over the conventional Zn reduction technique. The standard deviation, ~ 1-2???, is at least a factor of three better than that of the Zn reduction technique on urinary waters from diabetic volunteers. Experiments with pure water and solutions containing glucose, urea and albumen indicate that there is no measurable bias in the hydrogen equilibration technique.The H2-H2O ambient-temperature equilibration technique for the determination of 2H/1H ratios in urinary waters from diabetic subjects provides improved accuracy over the conventional Zn reduction technique. The standard deviation, approximately 1-2%, is at least a factor of three better than that of the Zn reduction technique on urinary waters from diabetic volunteers. Experiments with pure water and solutions containing glucose, urea and albumen indicate that there is no measurable bias in the hydrogen equilibration technique.

  7. Improved watermelon quality using bottle gourd rootstock expressing a Ca(2+)/H(+) antiporter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bottle gourd ("Lagenaria siceraria" Standl.) has been commonly used as a source of rootstock for watermelon. To improve its performance as a rootstock without adverse effects on the scion, the bottle gourd was genetically engineered using a modified "Arabidopsis" Ca(2+)/H(+) exchanger sCAX2B. This t...

  8. TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OL)

    Atmospheric Science Data Center

    2015-02-06

    TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OL) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Water Vapor Spatial Coverage:  27 x 23 km Limb ... Access: OPeNDAP Parameters:  H2O Water Volume Mixing Radio Precision Vertical Resolution Order ...

  9. Turbulence in Supercritical O2/H2 and C7H16/N2 Mixing Layers

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth; Okong'o, Nora

    2003-01-01

    This report presents a study of numerical simulations of mixing layers developing between opposing flows of paired fluids under supercritical conditions, the purpose of the study being to elucidate chemical-species-specific aspects of turbulence. The simulations were performed for two different fluid pairs O2/H2 and C7H16/N2 at similar reduced initial pressures (reduced pressure is defined as pressure divided by critical pressure). Thermodynamically, O2/H2 behaves more nearly like an ideal mixture and has greater solubility, relative to C7H16/N2, which departs strongly from ideality. Because of a specified smaller initial density stratification, the C7H16/N2 layers exhibited greater levels of growth, global molecular mixing, and turbulence. However, smaller density gradients at the transitional state for the O2/H2 system were interpreted as indicating that locally, this system exhibits enhanced mixing as a consequence of its greater solubility and closer approach to ideality. These thermodynamic features were shown to affect entropy dissipation, which was found to be larger for O2/H2 and concentrated in high-density-gradient-magnitude regions that are distortions of the initial density-stratification boundary. In C7H16/N2, the regions of largest dissipation were found to lie in high-density-gradient-magnitude regions that result from mixing of the two fluids.

  10. Raman and Brillouin scattering studies of bulk 2H-WSe2.

    PubMed

    Akintola, K; Andrews, G T; Curnoe, S H; Koehler, M R; Keppens, V

    2015-10-01

    Raman and Brillouin spectroscopy were used to probe optic and acoustic phonons in bulk 2H-WSe2. Raman spectra collected under different polarization conditions allowed assignment of spectral peaks to various first- and second-order processes. In contrast to some previous studies, a Raman peak at  ∼259 cm(-1)was found not to be due to the A(1g) mode but to a second-order process involving phonons at either the M or K point of the Brillouin zone. Resonance effects due to excitons were also observed in the Raman spectra. Brillouin spectra of 2H-WSe2 contain a single peak doublet arising from a Rayleigh surface mode propagating with a velocity of [Formula: see text] m s(-1). This value is comparable to that estimated from Density Functional Theory calculations and also to those for the transition metal diselenides 2H-TaSe2 and 2H-NbSe2. Unlike these two materials, however, peaks arising from scattering via the elasto-optic mechanism were not observed in Brillouin spectra of WSe2 despite its lower opacity. PMID:26381161

  11. Mutant and overexpression analysis of a C2H2 single zinc finger gene of Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this work was to characterize an Arabidopsis C2H2 single zinc finger gene, named AtZFP11, that is similar to SUPERMAN (SUP) and RABBIT EARS (RBE). No altered phenotype was observed in mutants analyzed that were derived through TILLING, nor a T-DNA insertion into the exon of AtZFP11. Pl...

  12. TES/Aura L2 Water Vapor (H2O) Nadir (TL2H2ON)

    Atmospheric Science Data Center

    2015-01-30

    TES/Aura L2 Water Vapor (H2O) Nadir (TL2H2ON) News:  TES News ... Title:  TES Discipline:  Tropospheric Chemistry Level:  L2 Instrument:  TES/Aura L2 Water Vapor Spatial Coverage:  5.3 x 8.5 km nadir ...

  13. TES/Aura L2 Water Vapor (H2O) Nadir (TL2H2ONS)

    Atmospheric Science Data Center

    2015-01-30

    TES/Aura L2 Water Vapor (H2O) Nadir (TL2H2ONS) News:  TES News ... Title:  TES Discipline:  Tropospheric Chemistry Level:  L2 Platform:  TES/Aura L2 Water Vapor Spatial Coverage:  5.3 8.5 km nadir ...

  14. "In planta" regulation of the "Arabidopsis" Ca(2+)/H(+) antiporter CAX1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vacuolar localized Ca(2+)/H(+) exchangers such as "Arabidopsis thaliana" cation exchanger 1 (CAX1) play important roles in Ca(2+) homeostasis. When expressed in yeast, CAX1 is regulated via an N-terminal autoinhibitory domain. In yeast expression assays, a 36 amino acid N-terminal truncation of CAX1...

  15. Fluorescence from photoexcitation of C2H5OH by vacuum ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Suto, Masako; Lee, L. C.

    1989-01-01

    The photoabsorption and fluorescence cross sections of C2H5OH have been measured in the 46-200 nm region. Fluorescence is dispersed to identify the emission systems, which are mainly OH(A-X), CH(A,B-X), and the H Balmer series. The photodissociation processes that produce the observed emissions are discussed.

  16. Preliminary investigations on the synthesis and antitumor activity of 3(2H)-furanones.

    PubMed

    Rappai, J P; Raman, V; Unnikrishnan, P A; Prathapan, S; Thomas, S K; Paulose, C S

    2009-02-01

    Two triaryl-3(2H)-furanones were synthesized and their antitumor activity was evaluated. These compounds inhibited the proliferation of DLA cell line in vitro. In vivo studies also showed that these compounds were active against tumor cell proliferation. PMID:19121938

  17. Gamow-Teller decay studies with 2p-2h configurations

    NASA Astrophysics Data System (ADS)

    Severyukhin, A. P.; Voronov, V. V.; Borzov, I. N.; Arsenyev, N. N.; Van Giai, Nguyen

    2016-06-01

    Starting from a Skyrme interaction with tensor terms, the β-decay rates have been studied within a microscopic model including the 2p-2h configuration effects. As an application we present the evolution of the neutron-rich Ni isotopes near 78Ni that are important for stellar nucleosynthesis.

  18. 77 FR 47169 - Clearing Requirement Determination Under Section 2(h) of the CEA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-07

    ... Commodity Exchange Act, 76 FR 77728 (Dec. 14, 2011). Clearing is at the heart of the Dodd-Frank financial...; and (4) the staying of a clearing requirement. \\19\\ See 76 FR 44464 (July 26, 2011); 17 CFR 39.5. This... under Section 2(h) of the CEA, 76 FR 58186 (Sept. 20, 2011). This comment letter is available on...

  19. The C-H Dissociation Energy of C2H6

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R. (Technical Monitor)

    1994-01-01

    The C-H bond energy in C2H6 is computed to be 99.76 +/- 0.35 kcal/mol, which is in excellent agreement with the most recent experimental values. The calculation of the C-H bond energy by direct dissociation and by an isodesmic reaction is discussed.

  20. Conformation of NH 3 and C 2H 4 molecules approaching a metal surface

    NASA Astrophysics Data System (ADS)

    Flores, F.; Gabbay, I.; March, N. H.

    1981-10-01

    Using a semiempirical approach to the conformation of free space molecules, the HNH angle in NH 3 adsorbed on Ru(001) is estimated to increase by about 1°. For C 2H 4, both HCC and HCH angles are predicted to decrease.

  1. Photo-induced reactions in the ion-molecule complex Mg+-OCNC2H5

    NASA Astrophysics Data System (ADS)

    Sun, Ju-Long; Liu, Haichuan; Han, Ke-Li; Yang, Shihe

    2003-06-01

    Ion-molecule complexes of magnesium cation with ethyl isocyanate were produced in a laser-ablation supersonic expansion nozzle source. Photo-induced reactions in the 1:1 complexes have been studied in the spectral range of 230-410 nm. Photodissociation mass spectrometry revealed the persistent product Mg+ from nonreactive quenching throughout the entire wavelength range. As for the reactive channels, the photoproducts, Mg+OCN and C2H5+, were produced only in the blue absorption band of the complex with low yields. The action spectrum of Mg+(OCNC2H5) consists of two pronounced peaks on the red and blue sides of the Mg+ 32P←32S atomic transition. The ground state geometry of Mg+-OCNC2H5 was fully optimized at B3LYP/6-31+G** level by using GAUSSIAN 98 package. The calculated absorption spectrum of the complex using the optimized structure of its ground state agrees well with the observed action spectrum. Photofragment branching fractions of the products are almost independent of the photolysis photon energy for the 3Px,y,z excitations. The very low branching ratio of reactive products to nonreactive fragment suggests that evaporation is the main relaxation pathway in the photo-induced reactions of Mg+(OCNC2H5).

  2. Rapid identification of osmolytes in tropical microalgae and cyanobacteria by (1)H HR-MAS NMR spectroscopy.

    PubMed

    Zea Obando, Claudia; Linossier, Isabelle; Kervarec, Nelly; Zubia, Mayalen; Turquet, Jean; Faÿ, Fabienne; Rehel, Karine

    2016-06-01

    In this study, we report the chemical characterization of 47 tropical microalgae and cyanobacteria by HR-MAS. The generated data confirm the interest of HR-MAS as a rapid screening technique with the major advantage of its easiness. The sample is used as powder of freeze-dried microalgae without any extraction process before acquisition. The spectral fingerprints of strains are then tested as variables for a chemotaxonomy study to discriminate cyanobacteria and dinoflagellates. The individual factor map generated by PCA analysis succeeds in separating the two groups, essentially thanks to the presence of specific carbohydrates. Furthermore, more resolved signals enable to identify many osmolytes. More precisely the characteristics δ of 2-O-alpha-D-glucosylglycerol (GG) are observed in all 21 h-MAS spectra of tropical cyanobacteria. After specific extraction, complementary analysis by 1D and 2D-NMR spectroscopies validates the identification of this osmolyte. PMID:27130130

  3. A 4-mm Probe for C-13 CP/MAS NMR of Solids at 21.15 T

    SciTech Connect

    Jakobsen, Hans J.; Daugaard, P; Hald, E; Rice, D; Kupce, Eriks; Ellis, Paul D. )

    2002-05-31

    With the recent announcement of a persistent 21.15 Tesla (i.e., 900 MHz for 1H NMR) narrow-bore (54 mm bore) superconducting magnet by Oxford Instruments and the associated Unity INOVA-900 console by Varian Inc. we were challenged with the task of designing a double-resonance broadband solid-state magic-angle spinning (MAS) NMR probe in particular for evaluating the 13C-{1H} cross-polarization (CP) MAS NMR experiment on this magnet and spectrometer system. In this communication we report the successful construction of an efficient X-1H/19F double resonance multinuclear MAS probe for this purpose along with our preliminary results on its performance at the 900 MHz spectrometer.

  4. LITERATURE REVIEW ON IMPACT OF GLYCOLATE ON THE 2H EVAPORATOR AND THE EFFLUENT TREATMENT FACILITY

    SciTech Connect

    Adu-Wusu, K.

    2012-05-10

    Glycolic acid (GA) is being studied as an alternate reductant in the Defense Waste Processing Facility (DWPF) feed preparation process. It will either be a total or partial replacement for the formic acid that is currently used. A literature review has been conducted on the impact of glycolate on two post-DWPF downstream systems - the 2H Evaporator system and the Effluent Treatment Facility (ETF). The DWPF recycle stream serves as a portion of the feed to the 2H Evaporator. Glycolate enters the evaporator system from the glycolate in the recycle stream. The overhead (i.e., condensed phase) from the 2H Evaporator serves as a portion of the feed to the ETF. The literature search revealed that virtually no impact is anticipated for the 2H Evaporator. Glycolate may help reduce scale formation in the evaporator due to its high complexing ability. The drawback of the solubilizing ability is the potential impact on the criticality analysis of the 2H Evaporator system. It is recommended that at least a theoretical evaluation to confirm the finding that no self-propagating violent reactions with nitrate/nitrites will occur should be performed. Similarly, identification of sources of ignition relevant to glycolate and/or update of the composite flammability analysis to reflect the effects from the glycolate additions for the 2H Evaporator system are in order. An evaluation of the 2H Evaporator criticality analysis is also needed. A determination of the amount or fraction of the glycolate in the evaporator overhead is critical to more accurately assess its impact on the ETF. Hence, use of predictive models like OLI Environmental Simulation Package Software (OLI/ESP) and/or testing are recommended for the determination of the glycolate concentration in the overhead. The impact on the ETF depends on the concentration of glycolate in the ETF feed. The impact is classified as minor for feed glycolate concentrations {le} 33 mg/L or 0.44 mM. The ETF unit operations that will have

  5. The Rate Constant for the Reaction H + C2H5 at T = 295 - 150K

    NASA Technical Reports Server (NTRS)

    Pimentel, Andre S.; Payne, Walter A.; Nesbitt, Fred L.; Cody, Regina J.; Stief, Louis J.

    2004-01-01

    The reaction between the hydrogen atom and the ethyl (C2H3) radical is predicted by photochemical modeling to be the most important loss process for C2H5 radicals in the atmospheres of Jupiter and Saturn. This reaction is also one of the major sources for the methyl radicals in these atmospheres. These two simplest hydrocarbon radicals are the initial species for the synthesis of larger hydrocarbons. Previous measurements of the rate constant for the H + C2H5 reaction varied by a factor of five at room temperature, and some studies showed a dependence upon temperature while others showed no such dependence. In addition, the previous studies were at higher temperatures and generally higher pressures than that needed for use in planetary atmospheric models. The rate constant for the reaction H + C2H5 has been measured directly at T = 150, 202 and 295 K and at P = 1.0 Torr He for all temperatures and additionally at P = 0.5 and 2.0 Torr He at T = 202 K. The measurements were performed in a discharge - fast flow system. The decay of the C2H5 radical in the presence of excess hydrogen was monitored by low-energy electron impact mass spectrometry under pseudo-first order conditions. H atoms and C2H5 radicals were generated rapidly and simultaneously by the reaction of fluorine atoms with H2 and C2H6, respectively. The total rate constant was found to be temperature and pressure independent. The measured total rate constant at each temperature are: k(sub 1)(295K) = (1.02+/-0.24)x10(exp -10), k(sub 1)(202K) = (1.02+/-0.22)x10(exp -10) and k(sub 1)(150K) = (0.93+/-0.21)x10(exp -10), all in units of cu cm/molecule/s. The total rate constant derived from all the combined measurements is k(sub 1) = (l.03+/-0.17)x10(exp -10) cu cm/molecule/s. At room temperature our results are about a factor of two higher than the recommended rate constant and a factor of three lower than the most recently published study.

  6. Role of Mas receptor in renal blood flow response to angiotensin (1-7) in male and female rats.

    PubMed

    Nematbakhsh, Mehdi; Safari, Tahereh

    2014-01-01

    Epidemiologic and clinical studies have shown that progression of renal disease in male is faster than that in female. However, the exact mechanisms are not well recognized. Angiotensin (1-7) (Ang 1-7) receptor, called "Mas", is an element in the depressor arm of renin angiotensin system (RAS), and its expression is enhanced in females. We test the hypothesis that Mas receptor (MasR) blockade (A779) attenuates renal blood flow (RBF) in response to infusion of graded doses of Ang 1-7 in female rats. Male and female Wistar rats were anesthetized and catheterized. Then, the mean arterial pressure (MAP), RBF, and controlled renal perfusion pressure (RPP) responses to infusion of graded doses of Ang 1-7 (100-1000 ng/kg/min i.v.) with and without A779 were measured in the animals. Basal MAP, RPP, RBF, and renal vascular resistance (RVR) were not significantly different between the two groups. After Ang 1-7 administration, RPP was controlled at a constant level. However, RBF increased in a dose-related manner in response to Ang 1-7 infusion in both male and female rats (Pdose<0.0001), but masR blockade significantly attenuated this response only in female (Pgroup=0.04) and not male (Pgroup=0.23). In addition, A779 increased the RBF response to Ang 1-7 to a greater extent. This is while the increase in male was not significant when compared with that in female (Pgender=0.08). RVR response to Ang 1-7 was insignificantly attenuated by A779 in both genders. The masR differently regulated RBF response to Ang 1-7 in the two genders, and the effect was greater in female rats. The masR may be a target for improvement of kidney circulation in renal diseases. PMID:24968411

  7. Synthesis of Open-Framework Iron Phosphates, [C 6N 2H 14][Fe III2F 2(HPO 4) 2(H 2PO 4) 2]·2H 2O and [C 6N 2H 14] 2[Fe III3(OH)F 3(PO 4)(HPO 4) 2] 2·H 2O, with One- and Three-Dimensional Structures

    NASA Astrophysics Data System (ADS)

    Mahesh, S.; Green, Mark A.; Natarajan, Srinivasan

    2002-05-01

    The hydrothermal syntheses and structures of two new open-framework iron phosphates, I, [C6N2H14][FeIII2F2(HPO4)2 (H2PO4)2].2H2O, II, and [C6N2H14]2[FeIII3(OH)F3(PO4) (HPO4)2]2. H2O, are presented. The structures of both I and II consist of FeO4F2 octahedra and PO4 terahedra linked to form one- and three-dimensional structures. Both the compounds possess infinite one-dimensional chains of Fe-O/F-Fe formed by the FeO4F2 octahedra. The di-protonated DABCO cations are located in between the chains in I and within the channels in II. Whilst I possess the tancoite structure with a new chain composition, II has a three-dimensional structure similar to the gallophosphate, ULM-1. Crystal data for I: M=685.84, monoclinic, space group=C2/c (no. 15), a=7.232(2), b=20.520(7), c=13.933(4) Å, β=97.68(3)°, ν=2049.1(1) Å3, Z=4, ρcalc.=2.223 g cm-3, μ(MoKα)=1.841 mm-1, R1=0.06, wR2=0.12, S=1.17 for 163 parameters; II, M=1303.33, monoclinic, space group =C2/c (no. 15), a=18.1836(2), b=10.0126(7), c=20.0589(4) Å, β=106.08(3)°, ν=3509.0(2) Å3, Z=4, ρcalc=2.467 g cm-3, μ(MoKα)=2.830 mm-1, R1=0.034, wR2=0.081, S=1.06 for 284 parameters.

  8. Microbial H2 cycling does not affect δ2H values of ground water

    USGS Publications Warehouse

    Landmeyer, J.E.; Chapelle, F.H.; Bradley, P.M.

    2000-01-01

    Stable hydrogen-isotope values of ground water (δ2H) and dissolved hydrogen concentrations (H(2(aq)) were quantified in a petroleum-hydrocarbon contaminated aquifer to determine whether the production/consumption of H2 by subsurface microorganisms affects ground water &delta2H values. The range of &delta2H observed in monitoring wells sampled (-27.8 ‰c to -15.5 ‰c) was best explained, however, by seasonal differences in recharge temperature as indicated using ground water δ18O values, rather than isotopic exchange reactions involving the microbial cycling of H2 during anaerobic petroleum-hydrocarbon biodegradation. The absence of a measurable hydrogen-isotope exchange between microbially cycled H2 and ground water reflects the fact that the amount of H2 available from the anaerobic decomposition of petroleum hydrocarbons is small relative to the amount of hydrogen present in water, even though milligram per liter concentrations of readily biodegradable contaminants are present at the study site. Additionally, isotopic fractionation calculations indicate that in order for H2 cycling processes to affect δ2H values of ground water, relatively high concentrations of H2 (>0.080 M) would have to be maintained, considerably higher than the 0.2 to 26 nM present at this site and characteristic of anaerobic conditions in general. These observations suggest that the conventional approach of using δ2H and δ18O values to determine recharge history is appropriate even for those ground water systems characterized by anaerobic conditions and extensive microbial H2 cycling.

  9. The 13C/2H-glucose test for determination of small intestinal lactase activity.

    PubMed

    Vonk, R J; Stellaard, F; Priebe, M G; Koetse, H A; Hagedoorn, R E; De Bruijn, S; Elzinga, H; Lenoir-Wijnkoop, I; Antoine, J M

    2001-03-01

    To diagnose hypolactasia, determination of lactase enzyme activity in small intestinal biopsy material is considered to be the golden standard. Because of its strongly invasive character and the sampling problems, alternative methods have been looked for. We analysed the 13C-glucose response in serum after consumption of 25 g of naturally enriched 13C-lactose. As an internal standard, 0.5 g of 2H-glucose was added and the 2H-glucose response in serum was measured simultaneously. The studies were performed in healthy volunteers with a background of genetically determined lactase nonpersistence (n = 12; low lactase activity) and lactase persistence (n = 27; high lactase activity). The results were compared with those of the lactose hydrogen breath test, the lactose 13CO2 breath test and the previously described 13C-lactose digestion test. After consumption of 13C-lactose and 2H-glucose, the mean ratio 13C-glucose/2H-glucose concentration in serum at 45-75 min was 0.26 +/- 0.09 in the low lactase activity group and 0.93 +/- 0.17 in the high lactase activity group (P < 0.01). Threshold of the ratio between digesters and maldigesters was calculated as 0.46. Accuracy of the new test was superior to all other tests. We conclude that the 13C/2H-glucose test has the potential of determining the small intestinal lactase activity in vivo and of estimating the amount of lactose which is digested in the small intestine. PMID:11264650

  10. Assessing the fate and transformation of plant residues in the terrestrial environment using HR-MAS NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kelleher, Brian P.; Simpson, Myrna J.; Simpson, Andre J.

    2006-08-01

    Plant litter decomposition plays a fundamental role in carbon and nitrogen cycles, provides key nutrients to the soil environment and represents a potentially large positive feedback to atmospheric CO 2. However, the full details of decomposition pathways and products are unknown. Here we present the first application of HR-MAS NMR spectroscopy on 13C and 15N labeled plant materials, and apply this approach in a preliminary study to monitor the environmental degradation of the pine and wheatgrass residues over time. In HR-MAS, is it possible to acquire very high resolution NMR data of plant biomass, and apply the vast array of multidimensional experiments available in conventional solution-state NMR. High levels of isotopic enrichment combined with HR-MAS significantly enhance the detection limits, and provide a wealth of information that is unattainable by any other method. Diffusion edited HR-MAS NMR data reveal the rapid loss of carbohydrate structures, while two-dimensional (2-D) HR-MAS NMR spectra demonstrate the relatively fast loss of both hydrolysable and condensed tannin structures from all plant tissues studied. Aromatic (partially lignin) and aliphatic components (waxes, cuticles) tend to persist, along with a small fraction of carbohydrate, and become highly functionalized over time. While one-dimensional (1-D) 13C HR-MAS NMR spectra of fresh plant tissue reflect compositional differences between pine and grass, these differences become negligible after decomposition suggesting that recalcitrant carbon may be similar despite the plant source. Two-dimensional 1H- 15N HR-MAS NMR analysis of the pine residue suggests that nitrogen from specific peptides is either selectively preserved or used for the synthesis of what appears to be novel structures. The amount of relevant data generated from plant components in situ using HR-MAS NMR is highly encouraging, and demonstrates that complete assignment will yield unprecedented structural knowledge of plant cell

  11. Fundamental Science Tools for Geologic Carbon Sequestration and Mineral Carbonation Chemistry: In Situ Magic Angle Spinning (MAS) Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Hoyt, D. W.; Turcu, R. V.; Sears, J. A.; Rosso, K. M.; Burton, S. D.; Kwak, J.; Felmy, A. R.; Hu, J.

    2010-12-01

    GCS is one of the most promising ways of mitigating atmospheric greenhouse gases. Mineral carbonation reactions are potentially important to the long-term sealing effectiveness of caprock but remain poorly predictable, particularly reactions occurring in low-water supercritical CO2(scCO2)-dominated environments where the chemistry has not been adequately explored. In situ probes that provide molecular-level information is desirable for investigating mechanisms and rates of GCS mineral carbonation reactions. MAS-NMR is a powerful tool for obtaining detailed molecular structure and dynamics information of a system regardless whether the system is in a solid, a liquid, a gaseous, or a supercritical state, or a mixture thereof. However, MAS NMR under scCO2 conditions has never been realized due to the tremendous technical difficulties of achieving and maintaining high pressure within a fast spinning MAS rotor. In this work, we report development of a unique high pressure MAS NMR capability, and its application to mineral carbonation chemistry in scCO2 under geologically relevant temperatures and pressures. Our high pressure MAS rotor has successfully maintained scCO2 conditions with minimal leakage over a period of 72 hours. Mineral carbonation reactions of a model magnesium silicate (forsterite) reacted with 96 bars scCO2 containing varying amounts of H2O (both below and above saturation of the scCO2) were investigated at 50○C. Figure 1 shows typical in situ 13C MAS NMR spectra demonstrating that the peaks corresponding to the reactants, intermediates, and the magnesium carbonation products are all observed in a single spectrum. For example, the scCO2 peak is located at 126.1 ppm. Reaction intermediates include the aqueous species HCO3-(160 ppm), partially hydrated/hydroxylated magnesium carbonates(166-168 ppm), and can easily be distinguished from final product magnesite(170 ppm). The new capability and this model mineral carbonation process will be overviewed in

  12. Two-dimensional MAS NMR correlation protocols involving double-quantum filtering of quadrupolar spin-pairs.

    PubMed

    Edén, Mattias

    2010-05-01

    Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t(2) domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t(1)) dimension. We employ experimental (23)Na and (27)Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl(2)O(5)), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations. PMID:20202872

  13. Proton chemical shift tensors determined by 3D ultrafast MAS double-quantum NMR spectroscopy

    SciTech Connect

    Zhang, Rongchun; Mroue, Kamal H.; Ramamoorthy, Ayyalusamy

    2015-10-14

    Proton NMR spectroscopy in the solid state has recently attracted much attention owing to the significant enhancement in spectral resolution afforded by the remarkable advances in ultrafast magic angle spinning (MAS) capabilities. In particular, proton chemical shift anisotropy (CSA) has become an important tool for obtaining specific insights into inter/intra-molecular hydrogen bonding. However, even at the highest currently feasible spinning frequencies (110–120 kHz), {sup 1}H MAS NMR spectra of rigid solids still suffer from poor resolution and severe peak overlap caused by the strong {sup 1}H–{sup 1}H homonuclear dipolar couplings and narrow {sup 1}H chemical shift (CS) ranges, which render it difficult to determine the CSA of specific proton sites in the standard CSA/single-quantum (SQ) chemical shift correlation experiment. Herein, we propose a three-dimensional (3D) {sup 1}H double-quantum (DQ) chemical shift/CSA/SQ chemical shift correlation experiment to extract the CS tensors of proton sites whose signals are not well resolved along the single-quantum chemical shift dimension. As extracted from the 3D spectrum, the F1/F3 (DQ/SQ) projection provides valuable information about {sup 1}H–{sup 1}H proximities, which might also reveal the hydrogen-bonding connectivities. In addition, the F2/F3 (CSA/SQ) correlation spectrum, which is similar to the regular 2D CSA/SQ correlation experiment, yields chemical shift anisotropic line shapes at different isotropic chemical shifts. More importantly, since the F2/F1 (CSA/DQ) spectrum correlates the CSA with the DQ signal induced by two neighboring proton sites, the CSA spectrum sliced at a specific DQ chemical shift position contains the CSA information of two neighboring spins indicated by the DQ chemical shift. If these two spins have different CS tensors, both tensors can be extracted by numerical fitting. We believe that this robust and elegant single-channel proton-based 3D experiment provides useful atomistic

  14. Tetrahydroxanthene-1,3(2H)-dione derivatives from Uvaria valderramensis.

    PubMed

    Macabeo, Allan Patrick G; Martinez, Franze Perry A; Kurtán, Tibor; Tóth, László; Mándi, Attila; Schmidt, Sebastian; Heilmann, Jörg; Alejandro, Grecebio Jonathan D; Knorn, Matthias; Dahse, Hans-Martin; Franzblau, Scott G

    2014-12-26

    Two tetrahydroxanthene-1,3(2H)-dione metabolites, valderramenols A (1) and B (2), were isolated from the Philippine endemic Annonaceous species Uvaria valderramensis. Planar structures of the rac-xanthene-1,3-(2H)-diones 1 and 2 were established by MS and NMR measurements. Their enantiomers were separated by chiral HPLC, and the absolute configurations of the separated enantiomers were determined by comparison of the HPLC-ECD spectra with computed TDDFT-generated spectra. A TDDFT-ECD study of the known grandiuvarone (3) allowed the revision of its absolute configuration as S. Compound 1 showed antitubercular activity (MIC 10 μg/mL), while 3 and 4 had weaker activities (MIC 32 μg/mL). Oxepinone 3 exhibited cytotoxic activity against KB-562, a chronic myeloid leukemia cell line. PMID:25372601

  15. Electron Transport Properties in HSi(OC2H5)3 Vapor

    NASA Astrophysics Data System (ADS)

    Yoshida, Kosaku; Sato, Ran; Yokota, Takuya; Kishimoto, Yasutaka; Date, Hiroyuki

    2011-12-01

    The electron swarm parameters in HSi(OC2H5)3 (triethoxysilane, TRIES) vapor have been investigated for relatively wide ranges of reduced electric field (E/N). Based on the arrival-time spectra (ATS) method for electrons using a double-shutter drift tube, the drift velocity and the longitudinal diffusion coefficient were measured for the E/N=20-5000 Td, and the ionization coefficient was obtained for E/N=300-5000 Td. The results were compared with those for SiH4 and Si(OC2H5)4 (tetraethoxysilane, TEOS), to show characteristics similar to the parameters in TEOS. We also determined the electron collision cross sections for TRIES by means of the Boltzmann equation analysis.

  16. Synthesis and Stereochemical Assignment of Crypto-Optically Active (2) H6 -Neopentane.

    PubMed

    Masarwa, Ahmad; Gerbig, Dennis; Oskar, Liron; Loewenstein, Aharon; Reisenauer, Hans Peter; Lesot, Philippe; Schreiner, Peter R; Marek, Ilan

    2015-10-26

    The determination of the absolute configuration of chiral molecules is at the heart of asymmetric synthesis. Here we probe the spectroscopic limits for chiral discrimination with NMR spectroscopy in chiral aligned media and with vibrational circular dichroism spectroscopy of the sixfold-deuterated chiral neopentane. The study of this compound presents formidable challenges since its stereogenicity is only due to small mass differences. For this purpose, we selectively prepared both enantiomers of (2) H6 -1 through a concise synthesis utilizing multifunctional intermediates. While NMR spectroscopy in chiral aligned media could be used to characterize the precursors to (2) H6 -1, the final assignment could only be accomplished with VCD spectroscopy, despite the fleetingly small dichroic properties of 1. Both enantiomers were assigned by matching the VCD spectra with those computed with density functional theory. PMID:26480341

  17. Isotopic Study ( 18O, 2H) of the Ground Water in the Bekaa's plain (Lebanon)

    NASA Astrophysics Data System (ADS)

    Awad, S.

    The stable isotopes of the water molecule (18O, 2H) give informations about the paleoclimate existing during the water seepage and about the recharge conditions of the groundwater. The effects of the Orography, the Continentality, and the origin of the masses of air have an effect on the isotopic abundance of the precipitations (rain + snow) in Lebanon. An evaporation of the recharge water exists in the atmosphere, with a mixing between the deep water and the shallow ones. The sea water has an isotopic abundance at 0 ‰ (SMOW: Standard Mean Ocean Water) for δ2H et δ18O, the Mediterranean Sea is at the origin of the rains which fall on the studied area, and which do not keep the isotopic abundances of the sea because the high mountains that they cross during their movement. This high altitude causes an impoverishment of the water of the rain on heavy isotope (18O).

  18. DIMMI-2h a MOF-based instrument for Solar Satellite ADAHELI

    NASA Astrophysics Data System (ADS)

    Stangalini, M.; Moretti, P. F.; Berrilli, F.; Del Moro, D.; Jefferies, S. M.; Severino, G.; Oliviero, M.

    2011-10-01

    The Doppler-Intensity-Magnetograms with a Magneto-optical filter Instrument at two heights (DIMMI-2h) is a double channel imager using Magneto Optical Filters (MOF) in the potassium 770 nm and sodium 589 nm lines. The instrument will provide simultaneous dopplergrams (velocity fields), continuum intensity and longitudinal magnetic flux images at two heights in the solar atmosphere corresponding to low and high photosphere. Dimmi- 2h is the possible piggy-back payload on ADAHELI satellite. The spatial resolution (approximately 4 arcsec) and the high temporal cadence (15 s) will permit to investigate low and medium oscillating modes (from 0 to below 1000) up to approximately 32 mHz in the frequency spectrum. The acquisition of long-term simultaneous velocity, intensity and magnetic information up to these high frequencies will permit also the study of the propagation and excitation of the waves with a frequency resolution never obtained before.

  19. Exploring a dynamical path for C2H- and NCO- formation in dark molecular clouds

    NASA Astrophysics Data System (ADS)

    Iskandarov, Ibrokhim; Gianturco, Francesco Antonio; Carelli, Fabio; Yurtsever, Ersin; Wester, Roland

    2016-02-01

    This paper deals with the possible formation of two molecular anions often considered likely components in the physical environments of the interstellar medium (ISM): C2H- and NCO-. They are both discussed here by computationally following the radiative association (RA) mechanism starting from C2-, H, N- and O as partners. The corresponding RA total cross sections produced by the calculations are in turn employed to generate the overall association rates over the relevant range of temperatures. The latter are found to be in line with other molecular ions formed by RA but not large enough to uniquivocally suggest this path as the main route to the anions formation in the ISM. Other possible paths of formation are also analysed and discussed. The presence of resonant structures during the association dynamics for both systems is found by the calculations and their consequences are discussed in some detail in the present study.

  20. The Dissociation Energies of CH4 and C2H2 Revisited

    NASA Technical Reports Server (NTRS)

    Partridge, Harry; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The bond dissociation energies of CH4 and C2H2 and their fragments are investigated using basis set extrapolations and high levels of correlation. The computed bond dissociation energies (D(sub e)) are accurate to within 0.2 kcal/mol. The agreement with the experimental (D(sub 0)) values is excellent if we assume that the zero-point energy of C2H is 9.18 kcal/mol. The effect of core (1s) correlation on the bond dissociation energies of C-H bonds is shown to vary from 0.2 to 0.7 kcal/mol and that for C-C bonds varies from 0.4 to 2.2 kcal/mol.

  1. Mixed H2/H(infinity)-Control with an output-feedback compensator using parameter optimization

    NASA Technical Reports Server (NTRS)

    Schoemig, Ewald; Ly, Uy-Loi

    1992-01-01

    Among the many possible norm-based optimization methods, the concept of H-infinity optimal control has gained enormous attention in the past few years. Here the H-infinity framework, based on the Small Gain Theorem and the Youla Parameterization, effectively treats system uncertainties in the control law synthesis. A design approach involving a mixed H(sub 2)/H-infinity norm strives to combine the advantages of both methods. This advantage motivates researchers toward finding solutions to the mixed H(sub 2)/H-infinity control problem. The approach developed in this research is based on a finite time cost functional that depicts an H-infinity bound control problem in a H(sub 2)-optimization setting. The goal is to define a time-domain cost function that optimizes the H(sub 2)-norm of a system with an H-infinity-constraint function.

  2. Simultaneous H2/H-infinity optimal control - The state feedback case

    NASA Technical Reports Server (NTRS)

    Saberi, Ali; Chen, Ben M.; Sannuti, Peddapullaiah; Ly, Uy-Loi

    1992-01-01

    A simultaneous H2/H-infinity control problem is considered. This problem seeks to minimize the H2 norm of a closed-loop transfer matrix while simultaneously satisfying a prescribed H-infinity norm bound on some other closed-loop transfer matrix by utilizing dynamic state feedback controllers. Such a problem was formulated earlier by Rotea and Khargonekar (1991) who considered only so called regular problems. Here, for a class of singular problems, necessary and sufficient conditions are established so that the posed simultaneous H2/H-infinity problem is solvable by using state feedback controllers. The class of singular problems considered have a left invertible transfer function matrix from the control input to the controlled output which is used for the H2 norm performance measure. This class of problems subsumes the class of regular problems.

  3. Mixed H(2)/H(sub infinity): Control with output feedback compensators using parameter optimization

    NASA Technical Reports Server (NTRS)

    Schoemig, Ewald; Ly, Uy-Loi

    1992-01-01

    Among the many possible norm-based optimization methods, the concept of H-infinity optimal control has gained enormous attention in the past few years. Here the H-infinity framework, based on the Small Gain Theorem and the Youla Parameterization, effectively treats system uncertainties in the control law synthesis. A design approach involving a mixed H(sub 2)/H-infinity norm strives to combine the advantages of both methods. This advantage motivates researchers toward finding solutions to the mixed H(sub 2)/H-infinity control problem. The approach developed in this research is based on a finite time cost functional that depicts an H-infinity bound control problem in a H(sub 2)-optimization setting. The goal is to define a time-domain cost function that optimizes the H(sub 2)-norm of a system with an H-infinity-constraint function.

  4. Optimized Spectral Editing of 13C MAS NMR Spectra of Rigid Solids Using Cross-Polarization Methods

    NASA Astrophysics Data System (ADS)

    Sangill, R.; Rastrupandersen, N.; Bildsoe, H.; Jakobsen, H. J.; Nielsen, N. C.

    Combinations of 13C magic-angle spinning (MAS) NMR experiments employing cross polarization (CP), cross polarization-depolarization (CPD), and cross polarization-depolarization-repolarization are analyzed quantitatively to derive simple and general procedures for optimized spectral editing of 13C CP/MAS NMR spectra of rigid solids by separation of the 13C resonances into CH n subspectra ( n = 0, 1, 2, and 3). Special attention is devoted to a differentiation by CPD/MAS of CH and CH 2 resonances since these groups behave quite similarly during spin lock under Hartmann-Hahn match and are therefore generally difficult to distinguish unambiguously. A general procedure for the design of subexperiments and linear combinations of their spectra to provide optimized signal-to-noise ratios for the edited subspectra is described. The technique is illustrated by a series of edited 13C CP/MAS spectra for a number of rigid solids ranging from simple organic compounds (sucrose and l-menthol) to complex pharmaceutical products (calcipotriol monohydrate and vitamin D 3) and polymers (polypropylene, polyvinyl alcohol, polyvinyl chloride, and polystyrene).

  5. States' Participation Guidelines for Alternate Assessments Based on Modified Academic Achievement Standards (AA-MAS) in 2008. Synthesis Report 71

    ERIC Educational Resources Information Center

    Lazarus, Sheryl S.; Rogers, Christopher; Cormier, Damien; Thurlow, Martha L.

    2008-01-01

    Federal regulations (U.S. Department of Education, 2007a) provide states with the flexibility to offer an alternate assessment based on modified academic achievement standards (AA-MAS). This assessment option is for a small group of students with disabilities who can make significant progress, but may not reach grade-level achievement within the…

  6. Coupled Ca2+/H+ transport by cytoplasmic buffers regulates local Ca2+ and H+ ion signaling.

    PubMed

    Swietach, Pawel; Youm, Jae-Boum; Saegusa, Noriko; Leem, Chae-Hun; Spitzer, Kenneth W; Vaughan-Jones, Richard D

    2013-05-28

    Ca(2+) signaling regulates cell function. This is subject to modulation by H(+) ions that are universal end-products of metabolism. Due to slow diffusion and common buffers, changes in cytoplasmic [Ca(2+)] ([Ca(2+)]i) or [H(+)] ([H(+)]i) can become compartmentalized, leading potentially to complex spatial Ca(2+)/H(+) coupling. This was studied by fluorescence imaging of cardiac myocytes. An increase in [H(+)]i, produced by superfusion of acetate (salt of membrane-permeant weak acid), evoked a [Ca(2+)]i rise, independent of sarcolemmal Ca(2+) influx or release from mitochondria, sarcoplasmic reticulum, or acidic stores. Photolytic H(+) uncaging from 2-nitrobenzaldehyde also raised [Ca(2+)]i, and the yield was reduced following inhibition of glycolysis or mitochondrial respiration. H(+) uncaging into buffer mixtures in vitro demonstrated that Ca(2+) unloading from proteins, histidyl dipeptides (HDPs; e.g., carnosine), and ATP can underlie the H(+)-evoked [Ca(2+)]i rise. Raising [H(+)]i tonically at one end of a myocyte evoked a local [Ca(2+)]i rise in the acidic microdomain, which did not dissipate. The result is consistent with uphill Ca(2+) transport into the acidic zone via Ca(2+)/H(+) exchange on diffusible HDPs and ATP molecules, energized by the [H(+)]i gradient. Ca(2+) recruitment to a localized acid microdomain was greatly reduced during intracellular Mg(2+) overload or by ATP depletion, maneuvers that reduce the Ca(2+)-carrying capacity of HDPs. Cytoplasmic HDPs and ATP underlie spatial Ca(2+)/H(+) coupling in the cardiac myocyte by providing ion exchange and transport on common buffer sites. Given the abundance of cellular HDPs and ATP, spatial Ca(2+)/H(+) coupling is likely to be of general importance in cell signaling. PMID:23676270

  7. Constraints on the δ2H diffusion rate in firn from field measurements at Summit, Greenland

    NASA Astrophysics Data System (ADS)

    Meijer, Harro A. J.; (L. G.) van der Wel, Gerko; Been, Henk A.; van de Wal, Roderik S. W.; (C. J. P. P) Smeets, Paul

    2015-04-01

    Diffusion smears out, and can eventually wash away, spatial gradients (such as seasonal cycles) in the stable isotope signals in snow and firn after deposition. The diffusion process is governed by the continuous evaporation and condensation of ice particles into and from the air channels. As this diffusion process influences the isotope signals that are eventually conserved in ice cores, quantitative knowledge of the process is necessary. We performed detailed 2H isotope diffusion measurements in the upper 3 meters of firn at Summit, Greenland. Using a small snow gun, a thin snow layer was formed from 2H-enriched water over a 6 x 6 m2 area. We followed the diffusion process, quantified as the increase of the δ2H diffusion length, over a four years period, by retrieving the layer once per year. Each year we drilled 2-3 firn cores, sliced them into 1 cm layers and measured the δ2H-signal of these layers. Our experimental findings show the gradual increase of the diffusion length to close to 4 cm after four years. This is much smaller than the result based on the commonly used model by Johnsen at al (2000), which yields more than 6 cm. We have studied the possible causes for this discrepancy, and conclude that the poor constraint of the tortuosity partly explains the discrepancy. But more important, it is likely that isotopic inhomogeneity exists within the ice grains in the firn, which slows down the diffusion process. This effect has not been considered in the model. Reference: S. Johnsen, K. Clausen, K. Cuffey, K. Hoffmann, J. Schwander, T. Creyts. Diffusion of stable isotopes in polar firn and ice: The isotope effect in firn diffusion. Physics of ice core Records (T. Hondoh, editor) Hokkaido University Press 2000.

  8. TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OLS)

    Atmospheric Science Data Center

    2015-01-30

    TES/Aura L2 Water Vapor (H2O) Limb (TL2H2OLS) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Water Vapor Spatial Coverage:  27 x 23 km Limb ... Access:  OPeNDAP Parameters:  H2O Water Volume Mixing Radio Precision Vertical Resolution Order ...

  9. Helicity in Supercritical O2/H2 and C7H16/N2 Mixing Layers

    NASA Technical Reports Server (NTRS)

    Okongo, Nora; Bellan, Josette

    2004-01-01

    This report describes a study of databases produced by direct numerical simulation of mixing layers developing between opposing flows of two fluids under supercritical conditions, the purpose of the study being to elucidate chemical-species-specific aspects of turbulence, with emphasis on helicity. The simulations were performed for two different fluid pairs -- O2/H2 and C7H16/N2 -- at similar values of reduced pressure.

  10. Electron Impact Ionization and Dissociative Ionization of C2H2

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.

    1995-01-01

    By utilizing a crossed electron beam collision geometry, a combination of time-of-flight (TOF) and quadrupole mass spectrometers, and the relative flow technique1 normalized values of cross sections and appearance energies (AP) were obtained for the formation of singly and multiply ionized species resulting from the ionization and dissociation of C2H2. Details ont he apparatus and technique have been published previously.2,3.

  11. A Neber approach for the synthesis of spiro-fused 2H-azirine-pyrazolone.

    PubMed

    Yue, Deng-Feng; Zhao, Jian-Qiang; Wang, Zhen-Hua; Zhang, Xiao-Mei; Xu, Xiao-Ying; Yuan, Wei-Cheng

    2016-02-14

    A base-mediated Neber reaction of enaminopyrazolones, which are the tautomers of 4-acyloxime-2-pyrazolin-5-ones, with sulfonyl chlorides was achieved. With this developed approach, a range of spiro-fused 2H-azirine-pyrazolones were obtained in good yields under mild conditions. A preliminary trial of a catalytic asymmetric version of the Neber reaction was conducted and gave promising enantioselectivity. PMID:26780927

  12. Palladium-catalyzed cross-dehydrogenative functionalization of C(sp(2))-H Bonds.

    PubMed

    Wu, Yinuo; Wang, Jun; Mao, Fei; Kwong, Fuk Yee

    2014-01-01

    The catalytic cross-dehydrogenative coupling (CDC) reaction has received intense attention in recent years. The attractive feature of this coupling process is the formation of a C-C bond from two C-H moieties under oxidative conditions. In this Focus Review, recent advances in the palladium-catalyzed CDC reactions of C(sp(2) )-H bond are summarized, with a focus on the period from 2011 to early 2013. PMID:24123795

  13. Band structure analysis of (1 × 2)-H/Pd(110)-pr

    NASA Astrophysics Data System (ADS)

    Shuttleworth, I. G.

    2013-09-01

    A novel method of band structure analysis based on the atomic orbital (AO) coefficients in LCAO-DFT has been applied to the (1 × 2)-H/Pd(110)-pr system. The analysis has revealed symmetry-dependent Pd 4d band splitting due to H ligand effects; ensemble effects due to the (1 × 2) Pd reconstruction are shown to be relatively minor.

  14. Temporal and spatial distributions of δ18O and δ2H in precipitation in Romania

    NASA Astrophysics Data System (ADS)

    Nagavciuc, Viorica; Bădăluță, Carmen-Andreea; Perșoiu, Aurel

    2015-04-01

    Stable isotope ratios of meteoric water have an important role in climatic, paleoclimatic, hydrological and meteorological studies. While such data are available from most of Europe, so far, in Romania (East Central Europe), no systematic study of the stable isotopic composition of precipitation exists. In this context, the aim of this study is to analyze the isotopic composition of rainwater, its temporal and spatial distribution, the identification of the main factors influencing these variations and the creation of the first map of spatial distribution of stable isotopes in precipitation in Romania. Between March 2012 and March 2014 we have collected monthly samples from 22 stations in Romania, which were subsequently analyzed for their δ18O and δ2H at the Stable Isotopes Laboratory, Stefan cel Mare University, Suceava, Romania. Precipitation in W and NW Romania plot along the GMWL, while those in the East are slightly below it, on an evaporative trend. The LMWL for Romania is defined as δ2H=7,27*δ18O + 6,92. The W-E gradient in the distribution of δ18O and δ2H are less marked than the N-S ones, with local influences dominating in areas of strong evaporation (intramountain basins, rain-shadow areas etc). In SW, and especially in autumn and winter, Meditteranean cyclones carry moisture from the Eastern Mediterranean, the δ18O and δ2H values in precipitation in the area plotting between the GMWL and the Eastern Mediterranean Meteoric Water Line. The isotopic composition of rainwater in Romania correlates well with air temperature, and is influenced to a lesser extent by other factors such as the amount of precipitation, topography configuration, the effect of continentalism and season of the year.

  15. Modeling studies of the chemical vapor deposition of boron films from B 2H 6

    NASA Astrophysics Data System (ADS)

    Lamborn, Daniel R.; Snyder, David W.; Xi, X. X.; Redwing, Joan M.

    2007-02-01

    The effect of growth conditions on the chemical vapor deposition of boron thin films from diborane (B 2H 6) was investigated using a combination of experimental studies and computational fluid dynamics-based reactor modeling. A multi-physics computational model was developed to simulate the thermal-fluid environment in the reactor. The proposed chemistry model incorporated into the simulations includes gas-phase decomposition and formation of B 2H 6 and surface adsorption and reaction of borane (BH 3). The model accurately predicts the experimentally measured temperature and partial pressure dependence of the boron growth rate using the sticking coefficient of BH 3 on the growth surface as the only adjustable parameter in the calculations. The results indicate that at lower growth temperatures (<500 °C) the boron growth rate is limited by gas-phase kinetics while at higher temperatures (>500 °C) the growth rate is limited by mass transfer of BH 3 to the substrate surface. The studies of boron thin film growth are relevant to the deposition of superconducting MgB 2 thin films, in which B 2H 6 is used as the boron precursor.

  16. NMR resonance splitting of urea in stretched hydrogels: proton exchange and (1)H/(2)H isotopologues.

    PubMed

    Kuchel, Philip W; Naumann, Christoph; Chapman, Bogdan E; Shishmarev, Dmitry; Håkansson, Pär; Bacskay, George; Hush, Noel S

    2014-10-01

    Urea at ∼12 M in concentrated gelatin gel, that was stretched, gave (1)H and (2)H NMR spectral splitting patterns that varied in a predictable way with changes in the relative proportions of (1)H2O and (2)H2O in the medium. This required consideration of the combinatorics of the two amide groups in urea that have a total of four protonation/deuteration sites giving rise to 16 different isotopologues, if all the atoms were separately identifiable. The rate constant that characterized the exchange of the protons with water was estimated by back-transformation analysis of 2D-EXSY spectra. There was no (1)H NMR spectral evidence that the chiral gelatin medium had caused in-equivalence in the protons bonded to each amide nitrogen atom. The spectral splitting patterns in (1)H and (2)H NMR spectra were accounted for by intra-molecular scalar and dipolar interactions, and quadrupolar interactions with the electric field gradients of the gelatin matrix, respectively. PMID:25241007

  17. Intragenic deletion of TRIM32 in compound heterozygotes with sarcotubular myopathy/LGMD2H.

    PubMed

    Borg, Kristian; Stucka, Rolf; Locke, Matthew; Melin, Eva; Ahlberg, Gabrielle; Klutzny, Ursula; Hagen, Maja von der; Huebner, Angela; Lochmüller, Hanns; Wrogemann, Klaus; Thornell, Lars-Eric; Blake, Derek J; Schoser, Benedikt

    2009-09-01

    In 2005 the commonality of sarcotubular myopathy (STM) and limb girdle muscular dystrophy type 2H (LGMD2H) was demonstrated, as both are caused by the p D487N missense mutation in TRIM32 originally found in the Manitoba Hutterite population. Recently, three novel homozygous TRIM32 mutations have been described in LGMD patients. Here we describe a three generation Swedish family clinically presenting with limb girdle muscular weakness and histological features of a microvacuolar myopathy. The two index patients were compound heterozygotes for a frameshift mutation in TRIM32 (c.1560delC ) and a 30 kb intragenic deletion, encompassing parts of intron 1 and the entire exon 2 of TRIM32. In these patients, no full-length or truncated TRIM32 could be detected. Interestingly, heterozygous family members carrying only one mutation showed mild clinical symptoms and vacuolar changes in muscle. In our family, the phenotype encompasses additionally a mild demyelinating polyneuropathic syndrome. Thus STM and LGMD2H are the result of loss of function mutations that can be either deletions or missense mutations. PMID:19492423

  18. A structural approach reveals how neighbouring C2H2 zinc fingers influence DNA binding specificity

    PubMed Central

    Garton, Michael; Najafabadi, Hamed S.; Schmitges, Frank W.; Radovani, Ernest; Hughes, Timothy R.; Kim, Philip M.

    2015-01-01

    Development of an accurate protein–DNA recognition code that can predict DNA specificity from protein sequence is a central problem in biology. C2H2 zinc fingers constitute by far the largest family of DNA binding domains and their binding specificity has been studied intensively. However, despite decades of research, accurate prediction of DNA specificity remains elusive. A major obstacle is thought to be the inability of current methods to account for the influence of neighbouring domains. Here we show that this problem can be addressed using a structural approach: we build structural models for all C2H2-ZF–DNA complexes with known binding motifs and find six distinct binding modes. Each mode changes the orientation of specificity residues with respect to the DNA, thereby modulating base preference. Most importantly, the structural analysis shows that residues at the domain interface strongly and predictably influence the binding mode, and hence specificity. Accounting for predicted binding mode significantly improves prediction accuracy of predicted motifs. This new insight into the fundamental behaviour of C2H2-ZFs has implications for both improving the prediction of natural zinc finger-binding sites, and for prioritizing further experiments to complete the code. It also provides a new design feature for zinc finger engineering. PMID:26384429

  19. Antinociceptive properties of new coumarin derivatives bearing substituted 3,4-dihydro-2H-benzothiazines

    PubMed Central

    2014-01-01

    Background Coumarins are an important class of widely distributed heterocyclic natural products exhibiting a broad pharmacological profile. In this work, a new series of coumarins bearing substituted 3,4-dihydro-2H-benzothiazines were described as potential analgesic agents. The clinical use of NSAIDs as traditional analgesics is associated with side effects such as gastrointestinal lesions and nephrotoxicity. Therefore, the discovery of new safer drugs represents a challenging goal for such a research area. Results The target compounds 3-(3-methyl-3,4-dihydro-2H-benzo[b][1,4]thiazin-3-yl)-2H-chromen-2-ones 2a-u were synthesized and characterized by spectral data. The antinociceptive properties of target compounds were determined by formalin-induced test and acetic acid-induced writhing test in mice. Among the tested compounds, compound 2u bearing 2-(4-(methylsulfonyl)benzoyl)- moiety on benzothiazine ring and 4-(methylsulfonyl)phenacyloxy- group on the 7 position of coumarin nucleus showed better profile of antinocecieption in both models. It was more effective than mefenamic acid during the late phase of formalin-induced test as well as in the acetic acid-induced writhing test. Conclusion Considering the significant antinoceciptive action of phenacyloxycoumarin derivatives, compound 2u prototype might be further used as model to obtain new more potent analgesic drugs. PMID:24398032

  20. Regulated release of Ca2+ from respiring mitochondria by Ca2+/2H+ antiport.

    PubMed

    Fiskum, G; Lehninger, A L

    1979-07-25

    Simultaneous measurements of oxygen consumption and transmembrane transport of Ca2+, H+, and phosphate show that the efflux of Ca2+ from respiring tightly coupled rat liver mitochondria takes place by an electroneutral Ca2+/2H+ antiport process that is ruthenium red-insensitive and that is regulated by the oxidation-reduction state of the mitochondrial pyridine nucleotides. When mitochondrial pyridine nucleotides are kept in a reduced steady state, the efflux of Ca2+ is inhibited; when they are in an oxidized state, Ca2+ efflux is activated. These processes were demonstrated by allowing phosphate-depleted mitochondria respiring on succinate in the presence of rotenone to take up Ca2+ from the medium. Upon subsequent addition of ruthenium red to block Ca2+ transport via the electrophoretic influx pathway, and acetoacetate, to bring mitochondrial pyridine nucleotides into the oxidized state, Ca2+ efflux and H+ influx ensued. The observed H+ influx/Ca2+ efflux ratio was close to the value 2.0 predicted for the operation of an electrically neutral Ca2+/2H+ antiport process. PMID:36390

  1. Liquid water on Mars - An energy balance climate model for CO2/H2O atmospheres

    NASA Technical Reports Server (NTRS)

    Hoffert, M. I.; Callegari, A. J.; Hsieh, C. T.; Ziegler, W.

    1981-01-01

    A simple climatic model is developed for a Mars atmosphere containing CO2 and sufficient liquid water to account for the observed hydrologic surface features by the existence of a CO2/H2O greenhouse effect. A latitude-resolved climate model originally devised for terrestrial climate studies is applied to Martian conditions, with the difference between absorbed solar flux and emitted long-wave flux to space per unit area attributed to the divergence of the meridional heat flux and the poleward heat flux assumed to equal the atmospheric eddy heat flux. The global mean energy balance is calculated as a function of atmospheric pressure to assess the CO2/H2O greenhouse liquid water hypothesis, and some latitude-resolved cases are examined in detail in order to clarify the role of atmospheric transport and temperature-albedo feedback. It is shown that the combined CO2/H2O greenhouse at plausible early surface pressures may account for climates hot enough to support a hydrological cycle and running water at present-day insolation and visible albedo levels.

  2. Detection of interstellar ethylene oxide (c-C2H4O).

    PubMed

    Dickens, J E; Irvine, W M; Ohishi, M; Ikeda, M; Ishikawa, S; Nummelin, A; Hjalmarson, A

    1997-11-10

    We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature T(rot) = 18 K and a molecular column density N(c-C2H4O) = 3.3 x 10(14) cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10(-11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW. PMID:11541726

  3. Exotic SiO2H2 Isomers: Theory and Experiment Working in Harmony.

    PubMed

    McCarthy, Michael C; Gauss, Jürgen

    2016-05-19

    Replacing carbon with silicon can result in dramatic and unanticipated changes in isomeric stability, as the well-studied CO2H2 and the essentially unknown SiO2H2 systems illustrate. Guided by coupled-cluster calculations, three SiO2H2 isomers have been detected and spectroscopically characterized in a molecular beam discharge source using rotational spectroscopy. The cis,trans conformer of dihydroxysilylene HOSiOH, the ground-state isomer, and the high-energy, metastable dioxasilirane c-H2SiO2 are abundantly produced in a dilute SiH4/O2 electrical discharge, enabling precise structural determinations of both by a combination of isotopic measurements and calculated vibrational corrections. The isotopic studies also provide insight into their formation route, suggesting that c-H2SiO2 is formed promptly in the expansion but that cis,trans-HOSiOH is likely formed by secondary reactions following formation of the most stable dissociation pair, SiO + H2O. Although less abundant, the rotational spectrum of trans-silanoic acid, the silicon analogue of formic acid, HSi(O)OH, has also been observed. PMID:27139016

  4. Preparation of bis-(1(2)H-tetrazol-5-yl)-amine monohydrate

    DOEpatents

    Naud, Darren L.; Hiskey, Michael A.

    2003-05-27

    A process of preparing bis-(1(2)H-tetrazol-5-yl)-amine monohydrate is provided including combining a dicyanamide salt, an azide salt and water to form a first reaction mixture, adding a solution of a first strong acid characterized as having a pKa of less than about 1 to said first reaction mixture over a period of time characterized as providing a controlled reaction rate so as to gradually form hydrazoic acid without loss of significant quantities of hydrazoic acid from the solution while heating the first reaction mixture at temperatures greater than about 65.degree. C., heating the resultant reaction mixture at temperatures greater than about 65.degree. C. for a period of time sufficient to substantially completely form a reaction product, treating the reaction product with a solution of a second strong acid to form a product of bis-(1(2)H-tetrazol-5-yl)-amine monohydrate, and, recovering the bis-(1(2)H-tetrazol-5-yl)-amine monohydrate product.

  5. Angular momentum of the N2H+ cores in the Orion A cloud

    NASA Astrophysics Data System (ADS)

    Tatematsu, Ken'ichi; Ohashi, Satoshi; Sanhueza, Patricio; Nguyen Luong, Quang; Umemoto, Tomofumi; Mizuno, Norikazu

    2016-04-01

    We have analyzed the angular momentum of the molecular cloud cores in the Orion A giant molecular cloud observed in the N2H+ J = 1-0 line with the Nobeyama 45 m radio telescope. We have measured the velocity gradient using position-velocity diagrams passing through core centers, and made sinusoidal fits against the position angle. Twenty-seven out of 34 N2H+ cores allowed us to measure the velocity gradient without serious confusion. The derived velocity gradient ranges from 0.5 to 7.8 km s-1 pc-1. We marginally found that the specific angular momentum J/M (against the core radius R) of the Orion N2H+ cores tends to be systematically larger than that of molecular cloud cores in cold dark clouds obtained by Goodman et al., in the J/M-R relation. The ratio β of rotational to gravitational energy is derived to be β = 10-2.3±0.7, and is similar to that obtained for cold dark cloud cores in a consistent definition. The large-scale rotation of the ∫-shaped filament of the Orion A giant molecular cloud does not likely govern the core rotation at smaller scales.

  6. Detection of Interstellar Ethylene Oxide (c-C2H4O)

    NASA Astrophysics Data System (ADS)

    Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, A.

    1997-01-01

    We report the identification of 10 transitions which support the detection of the small cyclic molecule ethylene oxide (c-C2H40) in SgrB2(N). Although one of these transitions is severely blended, such that an accurate intensity and linewidth could not be determined, and two other lines are only marginally detected, we have done gaussian fits to the remaining 7 lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature, Trot = 18 K, and a molecular column density, N(c-C2H40) = 3.3 x 1014cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10exp -11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst (1996). This result suggests that grain chemistry might play an effective role in the production Of c-C2H40. No transitions of this molecule were detected in either SgrB2(M) or SgrB2(NW).

  7. Detection of Interstellar Ethylene Oxide (c-C2H4O)

    NASA Astrophysics Data System (ADS)

    Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, Å.

    1997-11-01

    We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature Trot = 18 K and a molecular column density N(c-C2H4O) = 3.3 × 1014 cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 × 10-11. This is a factor of more than 200 higher than the abundance for this molecule suggested by the ``new standard'' chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW.

  8. Hydration and Lateral Organization in Phospholipid Bilayers Containing Sphingomyelin: A 2H-NMR Study

    PubMed Central

    Steinbauer, Bernhard; Mehnert, Thomas; Beyer, Klaus

    2003-01-01

    Interfacial properties of lipid bilayers were studied by 2H nuclear magnetic resonance spectroscopy, with emphasis on a comparison between phosphatidylcholine and sphingomyelin. Spectral resolution and sensitivity was improved by macroscopic membrane alignment. The motionally averaged quadrupolar interaction of interlamellar deuterium oxide was employed to probe the interfacial polarity of the membranes. The D2O quadrupolar splittings indicated that the sphingomyelin lipid-water interface is less polar above the phase transition temperature Tm than below Tm. The opposite behavior was found in phosphatidylcholine bilayers. Macroscopically aligned sphingomyelin bilayers also furnished 2H-signals from the amide residue and from the hydroxyl group of the sphingosine moiety. The rate of water-hydroxyl deuteron exchange could be measured, whereas the exchange of the amide deuteron was too slow for the inversion-transfer technique employed, suggesting that the amide residue is involved in intermolecular hydrogen bonding. Order parameter profiles in mixtures of sphingomyelin and chain-perdeuterated phosphatidylcholine revealed an ordering effect as a result of the highly saturated chains of the sphingolipids. The temperature dependence of the 2H quadrupolar splittings was indicative of lateral phase separation in the mixed systems. The results are discussed with regard to interfacial structure and lateral organization in sphingomyelin-containing biomembranes. PMID:12885648

  9. Modelling of c-C2H4O formation on grain surfaces

    NASA Astrophysics Data System (ADS)

    Occhiogrosso, A.; Viti, S.; Ward, M. D.; Price, S. D.

    2012-12-01

    Despite its potential reactivity due to ring strain, ethylene oxide (c-C2H4O) is a complex molecule that seems to be stable under the physical conditions of an interstellar dense core; indeed, it has been detected towards several high-mass star-forming regions with a column density of the order of 1013 cm-2. To date, its observational abundances cannot be reproduced by chemical models and this may be due to the significant contribution played by its chemistry on grain surfaces. Recently, Ward & Price have performed experiments in order to investigate the surface formation of ethylene oxide starting with oxygen atoms and ethylene ice as reactants. We present a chemical model which includes the most recent experimental results from Ward & Price on the formation of c-C2H4O. We study the influence of the physical parameters of dense cores on the abundances of c-C2H4O. We verify that ethylene oxide can indeed be formed during the cold phase (when the interstellar medium dense cores are formed), via addition of an oxygen atom across the C=C double bond of the ethylene molecule, and released by thermal desorption during the hot core phase. A qualitative comparison between our theoretical results and those from the observations shows that we are able to reproduce the abundances of ethylene oxide towards high-mass star-forming regions.

  10. CO2/H2 separation using a highly permeable polyurethane membrane: Molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Azizi, Morteza; Mousavi, Seyyed Abbas

    2015-11-01

    In this study, Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulations were conducted to investigate the diffusivity, solubility, and permeability of CO2, CO, H2, and H2O in a polyurethane membrane at three different temperatures. The characterization of the simulated structures was carried out using XRD, FFV, Tg and density calculation, and cavity size distribution. The obtained results were within the expectations reported data in the literature based on the experimental approach, indicating the authenticity of approached in this work. The results showed that the highest diffusivity and permeability coefficients were observed for H2; while the highest values of solubility coefficient were found for H2O and CO2 gases. The increase of operating temperature from 298 K to 318 K has a positive effect on the permeation of all gases and a corresponding negative effect on the selectivity of the gas pair CO2/H2. Also, the results vividly showed that CO2 and H2O gases have a profound affinity with hard phase of polyurethane, while H2 and CO were conversely adsorbed by soft one. Moreover, the enhancement of permeability and permselectivity of CO2/H2 pair confirmed using Robeson Upper-Bond graph showed its good capacity for CO2/H2 separation application.

  11. Laboratory IR Studies and Astrophysical Implications of C2H2-Containing Binary Ices

    NASA Astrophysics Data System (ADS)

    Knez, C.; Moore, M. H.; Ferrante, R. F.; Hudson, R. L.

    2012-04-01

    Studies of molecular hot cores and protostellar environments have shown that the observed abundance of gas-phase acetylene (C2H2) cannot be matched by chemical models without the inclusion of C2H2 molecules subliming from icy grain mantles. Searches for infrared (IR) spectral features of solid-phase acetylene are under way, but few laboratory reference spectra of C2H2 in icy mixtures, which are needed for spectral fits to observational data, have been published. Here, we report a systematic study of the IR spectra of condensed-phase pure acetylene and acetylene in ices dominated by carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and water (H2O). We present new spectral data for these ices, including band positions and intrinsic band strengths. For each ice mixture and concentration, we also explore the dependence of acetylene's ν5-band position (743 cm-1, 13.46 μm) and FWHM on temperature. Our results show that the ν5 feature is much more cleanly resolved in ices dominated by non-polar and low-polarity molecules, specifically CO, CO2, and CH4, than in mixtures dominated by H2O-ice. We compare our laboratory ice spectra with observations of a quiescent region in Serpens.

  12. The ACE2/Ang-(1-7)/Mas Axis Regulates the Development of Pancreatic Endocrine Cells in Mouse Embryos

    PubMed Central

    Wang, Lin; Liang, Juan; Leung, Po Sing

    2015-01-01

    Angiotensin-converting enzyme 2 (ACE2), its product Angiotensin-(1-7) [Ang-(1-7)], and Ang-(1-7) receptor Mas, have been shown to regulate organogenesis during embryonic development in various species. However, it is not known whether a local ACE2/Ang-(1-7)/Mas axis is present in the fetal pancreas. It is hypothesized that there is a local ACE2/Ang-(1-7)/Mas axis in the embryonic pancreas in mice that is involved in regulating islet cell development. To address this issue, the endogenous expression profile of axis constituents in embryonic mouse pancreata was examined. Involvement of the ACE2 axis in the regulation of pancreatic development was also examined. The present experiments showed in an in vivo animal model that endogenous expression levels of ACE2 and the Mas receptor were upregulated in mouse pancreata in late embryogenesis, peaking on embryonic day E16.5, when it reached 3 folds compared to that seen at E12.5. Consistently, endogenous expression of Ang-(1-7) also peaked at E16.5. Treatment with the ACE2 inhibitor DX600 did not alter islet development. However, prenatal treatment with A779, a Mas receptor antagonist, reduced the β-cell to α-cell ratio in neonatal islets, impaired islet insulin secretory function, and impaired the pups’ glucose tolerance. In ex vivo pancreas explant cultures, A779 again decreased the β-cell to α-cell ratio, apparently through its effects on β-cell proliferation (reduced proliferation shown with Ki67 staining), and also decreased Insulin and Ngn3 mRNA expression. Furthermore, treatment of explant cultures with Ang-(1-7) increased mRNA levels of Insulin and pancreatic progenitor marker Ngn3, as well as Nox4, the ROS generation enzyme; these stimulatory effects were attenuated by co-treatment with A779, suggesting that Ang-(1-7), via Mas receptor signaling, may promote differentiation of pancreatic progenitors into insulin-producing cells via modulation of reactive oxygen species. These data together suggest that a

  13. Identification of ancient Olea europaea L. and Cornus mas L. seeds by DNA barcoding.

    PubMed

    Gismondi, Angelo; Rolfo, Mario Federico; Leonardi, Donatella; Rickards, Olga; Canini, Antonella

    2012-07-01

    The analysis of ancient DNA (aDNA) provides archaeologists and anthropologists with innovative, scientific and accurate data to study and understand the past. In this work, ancient seeds, found in the "Mora Cavorso" archaeological site (Latium, Central Italy), were analyzed to increase information about Italian Neolithic populations (plant use, agriculture, diet, trades, customs and ecology). We performed morphological and genetic techniques to identify fossil botanical species. In particular, this study also suggests and emphasizes the use of DNA barcode method for ancient plant sample analysis. Scanning electron microscope (SEM) observations showed seed compact structure and irregular surface but they did not permit a precise nor empirical classification: so, a molecular approach was necessary. DNA was extracted from ancient seeds and then it was used, as template, for PCR amplifications of standardized barcode genes. Although aDNA could be highly degraded by the time, successful PCR products were obtained, sequenced and compared to nucleotide sequence databases. Positive outcomes (supported by morphological comparison with modern seeds, geographical distribution and historical data) indicated that seeds could be identified as belonging to two plant species: Olea europaea L. and Cornus mas L. PMID:22847014

  14. Structural investigations of borosilicate glasses containing MoO 3 by MAS NMR and Raman spectroscopies

    NASA Astrophysics Data System (ADS)

    Caurant, D.; Majérus, O.; Fadel, E.; Quintas, A.; Gervais, C.; Charpentier, T.; Neuville, D.

    2010-01-01

    High molybdenum concentration in glass compositions may lead to alkali and alkaline-earth molybdates crystallization during melt cooling that must be controlled particularly during the preparation of highly radioactive nuclear glassy waste forms. To understand the effect of molybdenum addition on the structure of a simplified nuclear glass and to know how composition changes can affect molybdates crystallization tendency, the structure of two glass series belonging to the SiO 2-B 2O 3-Na 2O-CaO-MoO 3 system was studied by 29Si, 11B, 23Na MAS NMR and Raman spectroscopies by increasing MoO 3 or B 2O 3 concentrations. Increasing MoO 3 amount induced an increase of the silicate network reticulation but no significant effect was observed on the proportion of BO4- units and on the distribution of Na + cations in glass structure. By increasing B 2O 3 concentration, a strong evolution of the distribution of Na + cations was observed that could explain the evolution of the nature of molybdate crystals (CaMoO 4 or Na 2MoO 4) formed during melt cooling.

  15. Immobilization of soluble protein complexes in MAS solid-state NMR: Sedimentation versus viscosity.

    PubMed

    Sarkar, Riddhiman; Mainz, Andi; Busi, Baptiste; Barbet-Massin, Emeline; Kranz, Maximilian; Hofmann, Thomas; Reif, Bernd

    2016-01-01

    In recent years, MAS solid-state NMR has emerged as a technique for the investigation of soluble protein complexes. It was found that high molecular weight complexes do not need to be crystallized in order to obtain an immobilized sample for solid-state NMR investigations. Sedimentation induced by sample rotation impairs rotational diffusion of proteins and enables efficient dipolar coupling based cross polarization transfers. In addition, viscosity contributes to the immobilization of the molecules in the sample. Natural Deep Eutectic Solvents (NADES) have very high viscosities, and can replace water in living organisms. We observe a considerable amount of cross polarization transfers for NADES solvents, even though their molecular weight is too low to yield significant sedimentation. We discuss how viscosity and sedimentation both affect the quality of the obtained experimental spectra. The FROSTY/sedNMR approach holds the potential to study large protein complexes, which are otherwise not amenable for a structural characterization using NMR. We show that using this method, backbone assignments of the symmetric proteasome activator complex (1.1MDa), and high quality correlation spectra of non-symmetric protein complexes such as the prokaryotic ribosome 50S large subunit binding to trigger factor (1.4MDa) are obtained. PMID:27017576

  16. Observations of radio-quiet quasars at 10-mas resolution by use of gravitational lensing

    NASA Astrophysics Data System (ADS)

    Jackson, Neal; Tagore, Amitpal S.; Roberts, Carl; Sluse, Dominique; Stacey, Hannah; Vives-Arias, Hector; Wucknitz, Olaf; Volino, Filomena

    2015-11-01

    We present Very Large Array detections of radio emission in 4 four-image gravitational lens systems with quasar sources: HS 0810+2554, RX J0911+0511, HE 0435-1223 and SDSS J0924+0219, and extended Multi-Element Remote Linked Interferometer (e-MERLIN) observations of two of the systems. The first three are detected at a high level of significance, and SDSS J0924+0219 is detected. HS 0810+2554 is resolved, allowing us for the first time to achieve 10-mas resolution of the source frame in the structure of a radio-quiet quasar. The others are unresolved or marginally resolved. All four objects are among the faintest radio sources yet detected, with intrinsic flux densities in the range 1-5 μJy; such radio objects, if unlensed, will only be observable routinely with the Square Kilometre Array. The observations of HS 0810+2554, which is also detected with e-MERLIN, strongly suggest the presence of a mini active galactic nucleus, with a radio core and milliarcsecond scale jet. The flux densities of the lensed images in all but HE 0435-1223 are consistent with smooth galaxy lens models without the requirement for smaller scale substructure in the model, although some interesting anomalies are seen between optical and radio flux densities. These are probably due to microlensing effects in the optical.

  17. The Neuroprotective Effect of Cornus mas on Brain Tissue of Wistar Rats

    PubMed Central

    Francik, Renata; Kryczyk, Jadwiga; Krośniak, Mirosław; Berköz, Mehmet; Sanocka, Ilona; Francik, Sławomir

    2014-01-01

    Cornelian cherry (Cornus mas) is a valuable source of phenolic antioxidants. Flavonoid derivatives as nonenzymatic antioxidants are important in the pathophysiology of many diseases including neurological disorders (e.g., Alzheimer's disease) or heart disease. In this study, we examined the effect of an addition of freeze-dried fruit of cornelian cherry on three types of diets: control diet, fructose diet, and diet enriched in fats (high-fat diet). This effect was studied by determining the following antioxidant parameters in both brain tissue and plasma in rats: catalase, ferric reducing ability of plasma, paraoxonase, protein carbonyl groups, and free thiol groups. Results indicate that both fructose diet and high-fat diet affect the antioxidant capacity of the organism. Furthermore, an addition of cornelian cherry resulted in increased activity of catalase in brain tissue, while in plasma it caused the opposite effect. In turn, with regard to paraoxonase activity in both brain tissue and plasma, it had a stimulating effect. Adding cornelian cherry to the tested diets increased the activity of PON in both tested tissues. Moreover, protective effect of fruits of this plant was observed in the process of oxidation of proteins by decreasing levels of protein carbonyl groups and thiol groups in brain tissue as well as in plasma. PMID:25401157

  18. Broadband inversion for MAS NMR with single-sideband-selective adiabatic pulses

    NASA Astrophysics Data System (ADS)

    Pell, Andrew J.; Kervern, Gwendal; Emsley, Lyndon; Deschamps, Michaël; Massiot, Dominique; Grandinetti, Philip J.; Pintacuda, Guido

    2011-01-01

    We explain how and under which conditions it is possible to obtain an efficient inversion of an entire sideband family of several hundred kHz using low-power, sideband-selective adiabatic pulses, and we illustrate with some experimental results how this framework opens new avenues in solid-state NMR for manipulating spin systems with wide spinning-sideband (SSB) manifolds. This is achieved through the definition of the criteria of phase and amplitude modulation for designing an adiabatic inversion pulse for rotating solids. In turn, this is based on a framework for representing the Hamiltonian of the spin system in an NMR experiment under magic angle spinning (MAS). Following earlier ideas from Caravatti et al. [J. Magn. Reson. 55, 88 (1983)], the so-called "jolting frame" is used, which is the interaction frame of the anisotropic interaction giving rise to the SSB manifold. In the jolting frame, the shift modulation affecting the nuclear spin is removed, while the Hamiltonian corresponding to the RF field is frequency modulated and acquires a spinning-sideband pattern, specific for each crystallite orientation.

  19. One- and two-dimensional exchange J-resolved CP-MAS NMR spectrum of adamantane

    NASA Astrophysics Data System (ADS)

    Takegoshi, K.; McDowell, C. A.

    1986-02-01

    A combined technique of 1D and 2D exchange NMR and J-resolved CP-MAS NMR of dilute spins in solids and its application to study a spin exchange process of abundant spins in solids is described, and demonstrated for powdered adamantane. A high-resolution J-resolved NMR spectrum of a 13C nucleus obtained by applying homonuclear decoupling and magic angle sample spinning is employed to label the spin states of 1H spins bonded to the 13C nucleus. Perspective 2D exchange spectra are employed to map out connectivity between the proton spin states, and the rate constants for the 1H spin exchange involved are determined by 1D exchange NMR techniques. Discussions based on the total energy conservation enable us to conclude that the observed spin exchange processes are to be ascribed mainly to the flip-flop motion of 1H spins; the spin-lattice process is negligible. The rate constant for the flip-flop motion of the proton spins is determined to be (7±2)×103 s-1 at room temperature.

  20. 31P MAS-NMR of human erythrocytes: independence of cell volume from angular velocity.

    PubMed

    Kuchel, P W; Bubb, W A; Ramadan, S; Chapman, B E; Philp, D J; Coen, M; Gready, J E; Harvey, P J; McLean, A J; Hook, J

    2004-09-01

    31P magic angle spinning NMR (MAS-NMR) spectra were obtained from suspensions of human red blood cells (RBCs) that contained the cell-volume-sensitive probe molecule, dimethyl methylphosphonate (DMMP). A mathematical representation of the spectral-peak shape, including the separation and width-at-half-height in the 31P NMR spectra, as a function of rotor speed, enabled us to explore the extent to which a change in cell volume would be reflected in the spectra if it occurred. We concluded that a fractional volume change in excess of 3% would have been detected by our experiments. Thus, the experiments indicated that the mean cell volume did not change by this amount even at the highest spinning rate of 7 kHz. The mean cell volume and intracellular 31P line-width were independent of the packing density of the cells and of the initial cell volume. The relationship of these conclusions to other non-NMR studies of pressure effects on cells is noted. PMID:15334588

  1. Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR.

    PubMed

    Gumann, Sina; Nestle, Nikolaus; Liebau-Kunzmann, Verena; Riedel, Ralf

    2007-04-01

    Lithium-containing silicon (oxy)carbonitride ceramics (SiCN(O):Li) were synthesized via precursor-to-ceramic-transformation of Li-containing (poly)silazanes. The precursors were obtained by lithiation of 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane with n-butyllithium and by reaction of a commercial poly(organosilazane) VL20 with metallic lithium. The annealing treatment was carried out at temperatures between 200 and 1400 degrees C in argon (DeltaT=200 degrees C) and yielded Li-containing silicon (oxy)carbonitride. X-ray powder diffraction revealed that the resulting SiCN(O):Li ceramics were basically amorphous up to temperatures of 1000 degrees C and formed LiSi(2)N(3), graphite and silicon carbide as crystalline phases at higher temperatures. (7)Li MAS NMR spectroscopy was carried out to investigate the structure of the Li-containing phases and to study the reaction path of metallic Li with polysilazane. Based on the NMR spectra, there is almost no difference found in the chemical shift of the SiCN(O):Li ceramics obtained at different temperatures. Accordingly, Li is assigned to be mainly coordinated to N and O present as contaminant element. Relaxation time measurements showed that the most mobile Li(+) species seems to be present in the product obtained in the pyrolysis temperature range between 600 and 1000 degrees C. PMID:17418540

  2. Molybdenum modified phosphate glasses studied by 31P MAS NMR and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Szumera, Magdalena

    2015-02-01

    Glasses have been synthesized in the system P2O5sbnd SiO2sbnd K2Osbnd MgOsbnd CaO modified by addition of MoO3. Glasses were prepared by conventional fusion method from 40 g batches. The influence of Mo-cations on the analysed glass structure was investigated by means of Raman and 31P MAS-NMR techniques. It has been found that molybdate units can form Mo[MoO4/MoO6]sbnd Osbnd P and/or Mo[MoO4/MoO6]sbnd Osbnd Si bonds with non-bridging oxygens atoms of Q2 methaphosphate units, resulting in the transformation of chain methaphosphate structure into pyrophosphate and finally into orthophosphate structure. It has been also found that increasing amount of MoO3 in the structure of investigated glasses causes their gradual depolymerization and molybdenum ions in the analysed glass matrix act as modifying cations.

  3. DNP-Enhanced MAS NMR of Bovine Serum Albumin Sediments and Solutions

    PubMed Central

    2015-01-01

    Protein sedimentation sans cryoprotection is a new approach to magic angle spinning (MAS) and dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) spectroscopy of proteins. It increases the sensitivity of the experiments by a factor of ∼4.5 in comparison to the conventional DNP sample preparation and circumvents intense background signals from the cryoprotectant. In this paper, we investigate sedimented samples and concentrated frozen solutions of natural abundance bovine serum albumin (BSA) in the absence of a glycerol-based cryoprotectant. We observe DNP signal enhancements of ε ∼ 66 at 140 GHz in a BSA pellet sedimented from an aqueous solution containing the biradical polarizing agent TOTAPOL and compare this with samples prepared using the conventional protocol (i.e., dissolution of BSA in a glycerol/water cryoprotecting mixture). The dependence of DNP parameters on the radical concentration points to the presence of an interaction between TOTAPOL and BSA, so much so that a frozen solution sans cryoprotectant still gives ε ∼ 50. We have studied the interaction of BSA with another biradical, SPIROPOL, that is more rigid than TOTAPOL and has been reported to give higher enhancements. SPIROPOL was also found to interact with BSA, and to give ε ∼ 26 close to its maximum achievable concentration. Under the same conditions, TOTAPOL gives ε ∼ 31, suggesting a lesser affinity of BSA for SPIROPOL with respect to TOTAPOL. Altogether, these results demonstrate that DNP is feasible in self-cryoprotecting samples. PMID:24460530

  4. Low Temperature 1H MAS NMR Spectroscopy Studies of Proton Motion in Zeolite

    SciTech Connect

    Huo, H.; Peng, L; Grey, C

    2009-01-01

    Low temperature {sup 1}H MAS NMR spectroscopy is used to study protonic motion in zeolite HZSM-5 in both samples that have been dried using procedures that are standard in the literature and samples that have been more carefully dehydrated. A significant enhancement of proton mobility is seen for the ''standard'' dehydrated HZSM-5 sample in comparison to that seen for the much drier sample. This is ascribed to a vehicle-hopping mechanism involving the residual water that is present in these zeolites. A gradual change of the framework structure is observed on cooling to approximately 213 K, as monitored via the change in {sup 1}H chemical shift values of the Broensted acid resonances and by X-ray diffraction. A more sudden change in structure is seen by differential scanning calorimetry and NMR at approximately 220?230 K, which is associated with changes in both the mobility and the modes of binding of the residual water to the Broensted acid sites and the zeolite framework.

  5. The effect of biradical concentration on the performance of DNP-MAS-NMR

    NASA Astrophysics Data System (ADS)

    Lange, Sascha; Linden, Arne H.; Akbey, Ümit; Trent Franks, W.; Loening, Nikolaus M.; van Rossum, Barth-Jan; Oschkinat, Hartmut

    2012-03-01

    With the technique of dynamic nuclear polarization (DNP) signal intensity in solid-state MAS-NMR experiments can be enhanced by 2-3 orders of magnitude. DNP relies on the transfer of electron spin polarization from unpaired electrons to nuclear spins. For this reason, stable organic biradicals such as TOTAPOL are commonly added to samples used in DNP experiments. We investigated the effects of biradical concentration on the relaxation, enhancement, and intensity of NMR signals, employing a series of samples with various TOTAPOL concentrations and uniformly 13C, 15N labeled proline. A considerable decrease of the NMR relaxation times (T1, T2∗, and T1ρ) is observed with increasing amounts of biradical due to paramagnetic relaxation enhancement (PRE). For nuclei in close proximity to the radical, decreasing T1ρ reduces cross-polarization efficiency and decreases in T2∗ broaden the signal. Additionally, paramagnetic shifts of 1H signals can cause further line broadening by impairing decoupling. On average, the combination of these paramagnetic effects (PE; relaxation enhancement, paramagnetic shifts) quenches NMR-signals from nuclei closer than 10 Å to the biradical centers. On the other hand, shorter T1 times allow the repetition rate of the experiment to be increased, which can partially compensate for intensity loss. Therefore, it is desirable to optimize the radical concentration to prevent additional line broadening and to maximize the signal-to-noise observed per unit time for the signals of interest.

  6. Probing perturbation of bovine lung surfactant extracts by albumin using DSC and 2H-NMR.

    PubMed

    Nag, Kaushik; Keough, Kevin M W; Morrow, Michael R

    2006-05-15

    Lung surfactant (LS), a lipid-protein mixture, forms films at the lung air-water interface and prevents alveolar collapse at end expiration. In lung disease and injury, the surface activity of LS is inhibited by leakage of serum proteins such as albumin into the alveolar hypophase. Multilamellar vesicular dispersions of a clinically used replacement, bovine lipid extract surfactant (BLES), to which (2% by weight) chain-perdeuterated dipalmitoylphosphatidycholine (DPPG mixtures-d(62)) had been added, were studied using deuterium-NMR spectroscopy ((2)H-NMR) and differential scanning calorimetry (DSC). DSC scans of BLES showed a broad gel to liquid-crystalline phase transition between 10-35 degrees C, with a temperature of maximum heat flow (T(max)) around 27 degrees C. Incorporation of the DPPC-d(62) into BLES-reconstituted vesicles did not alter the T(max) or the transition range as observed by DSC or the hydrocarbon stretching modes of the lipids observed using infrared spectroscopy. Transition enthalpy change and (2)H-NMR order parameter profiles were not significantly altered by addition of calcium and cholesterol to BLES. (2)H-NMR spectra of the DPPC-d(62) probes in these samples were characteristic of a single average lipid environment at all temperatures. This suggested either continuous ordering of the bilayer through the transition during cooling or averaging of the DPPC-d(62) environment by rapid diffusion between small domains on a short timescale relative to that characteristic of the (2)H-NMR experiment. Addition of 10% by weight of soluble bovine serum albumin (1:0.1, BLES/albumin, dry wt/wt) broadened the transition slightly and resulted in the superposition of (2)H-NMR spectral features characteristic of coexisting fluid and ordered phases. This suggests the persistence of phase-separated domains throughout the transition regime (5-35 degrees C) of BLES with albumin. The study suggests albumin can cause segregation of protein bound-lipid domains in

  7. High-frequency observations of δ2H and δ18O in storm rainfall

    NASA Astrophysics Data System (ADS)

    Stoecker, F.; Klaus, J.; Pangle, L. A.; Garland, C.; McDonnell, J. J.

    2012-12-01

    Stable isotopes ratios of hydrogen (2H/1H) and oxygen (18O/16O) are indispensable tools for investigation of the hydrologic cycle. Recent technological advances with laser spectroscopy now enable high-frequency measurement of key water cycle components. While the controls on rainfall isotope composition have been known generally for some time, our understanding of the effect of inter- and intra-storm processes on fine scale rainfall isotope composition is poorly understood. Here we present a new approach to observe inter- and intra-storm isotope variability in precipitation in high-frequency. We investigate the temporal development of δ2H and δ18O within and between discrete rainstorm. δ2H and δ18O in precipitation was measured from November 2011 to February 2012 in Corvallis, OR using a flow-cell combined with a Liquid Water Isotope Analyzer (LWIA-24d, Los Gatos Research, Inc.). The average sample frequency was 15 samples per hour, resulting in more than 3100 samples during the observation period. 27 separate rainstorms were identified in the dataset based on minimum inter-event time, minimum precipitation depth, and minimum number of isotope measurements. Event meteoric water lines were developed for each event. We observed short-term isotopic patterns (e.g., V-shaped trends), high-rate changes (5.3‰/h) and large absolute changes in isotopic composition (20‰) on intra-event scale. V-shaped trends appeared to be related to individual storm fronts detected by air temperature, cloud heights (NEXRAD radar echo tops) and cloud trajectories (Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT)). Despite this, we could detect no linear correlation between event-based isotopic variables (slope, δ2H-intercept, δ2H, δ18O) and the event meteoric water line. Furthermore, the composite event meteoric water line (i.e. the local meteoric water line) showed a wider spread for heavy isotopes than for light isotopes, caused presumably by different

  8. Gas-phase CO2, C2H2, and HCN toward Orion-KL

    NASA Astrophysics Data System (ADS)

    Boonman, A. M. S.; van Dishoeck, E. F.; Lahuis, F.; Doty, S. D.; Wright, C. M.; Rosenthal, D.

    2003-03-01

    The infrared spectra toward Orion-IRc2, Peak 1 and Peak 2 in the 13.5-15.5 mu m wavelength range are presented, obtained with the Short Wavelength Spectrometer on board the Infrared Space Observatory. The spectra show absorption and emission features of the vibration-rotation bands of gas-phase CO2, HCN, and C2H2, respectively. Toward the deeply embedded massive young stellar object IRc2 all three bands appear in absorption, while toward the shocked region Peak 2 CO2, HCN, and C2H2 are seen in emission. Toward Peak 1 only CO2 has been detected in emission. Analysis of these bands shows that the absorption features toward IRc2 are characterized by excitation temperatures of ~ 175-275 K, which can be explained by an origin in the shocked plateau gas. HCN and C2H2 are only seen in absorption in the direction of IRc2, whereas the CO2 absorption is probably more widespread. The CO2 emission toward Peak 1 and 2 is best explained with excitation by infrared radiation from dust mixed with the gas in the warm component of the shock. The similarity of the CO2 emission and absorption line shapes toward IRc2, Peak 1 and Peak 2 suggests that the CO2 is located in the warm component of the shock (T ~ 200 K) toward all three positions. The CO2 abundances of ~ 10-8 for Peak 1 and 2, and of a few times 10-7 toward IRc2 can be explained by grain mantle evaporation and/or reformation in the gas-phase after destruction by the shock. The HCN and C2H2 emission detected toward Peak 2 is narrower (T ~ 50-150 K) and originates either in the warm component of the shock or in the extended ridge. In the case of an origin in the warm component of the shock, the low HCN and C2H2 abundances of ~ 10-9 suggest that they are destroyed by the shock or have only been in the warm gas for a short time (t <~ 104 yr). In the case of an origin in the extended ridge, the inferred abundances are much higher and do not agree with predictions from current chemical models at low temperatures. Based on

  9. 2H Stable Isotope Analysis of Tooth Enamel: A Pilot Study

    NASA Astrophysics Data System (ADS)

    Holobinko, Anastasia; Kemp, Helen; Meier-Augenstein, Wolfram; Prowse, Tracy; Ford, Susan

    2010-05-01

    Stable isotope analysis of biogenic tissues such as tooth enamel and bone mineral has become a well recognized and increasingly important method for determining provenance of human remains, and has been used successfully in bioarchaeological studies as well as forensic investigations (Lee-Thorp, 2008; Meier-Augenstein and Fraser, 2008). Particularly, 18O and 2H stable isotopes are well established proxies as environmental indicators of climate (temperature) and source water and are therefore considered as indicators of geographic life trajectories of animals and humans (Hobson et al., 2004; Schwarcz and Walker, 2006). While methodology for 2H analysis of human hair, fingernails, and bone collagen is currently used to determine geographic origin and identify possible migration patterns, studies involving the analysis of 2H in tooth enamel appear to be nonexistent in the scientific literature. The apparent lack of research in this area is believed to have two main reasons. (1) Compared to the mineral calcium hydroxylapatite Ca10(PO4)6(OH)2, in tooth enamel forming bio-apatite carbonate ions replace some of the hydroxyl ions at a rate of one CO32 replacing two OH, yet published figures for the degree of substitution vary (Wopenka and Pasteris, 2005). (2) Most probably due to the aforementioned no published protocols exist for sample preparation and analytical method to obtain δ2H-values from the hydroxyl fraction of tooth enamel. This dilemma has been addressed through a pilot study to establish feasibility of 2H stable isotope analysis of ground tooth enamel by continuous-flow isotope ratio mass spectrometry (IRMS) coupled on-line to a high-temperature conversion elemental analyzer (TC/EA). An array of archaeological and modern teeth has been analyzed under different experimental conditions, and results from this pilot study are being presented. References: Lee-Thorp, J.A. (2008) Archaeometry, 50, 925-950 Meier-Augenstein, W. and Fraser, I. (2008) Science & Justice

  10. Synthesis, crystal structure and vibrational spectroscopic analysis of tetrakis(5-amino-1-H-1,2,4-triazol-4-ium) decachlorodibismuthate(III):[C2H5N4]4Bi2Cl10

    NASA Astrophysics Data System (ADS)

    Aloui, Z.; Ferretti, V.; Abid, S.; Lefebvre, F.; Rzaigui, M.; Nasr, C. Ben

    2015-10-01

    Physico-chemical properties of a new organic bismuthate(III), [C2H5N4]4Bi2Cl10 are discussed on the basis of X-ray crystal structure investigation. This compound crystallizes in the monoclinic space group C2/c, with a = 16.3622(3), b = 12.7941(2), c = 14.8178(2) Å, β = 98.5660(10)°, V = 3067.35(8) Å3 and Z = 4. The crystal structure consists of discrete binuclear [Bi2Cl10]4- anions and 3-amino-1-H-1,2,4-triazolium cations. The crystal packing is governed by strong Nsbnd H⋯N and weak Nsbnd H⋯Cl hydrogen bonds and Π-Π stacking interactions to form three-dimensional network. The 13C CP-MAS NMR spectrum is in agreement with the X-ray structure. The infrared study confirms the presence of the organic cation [C2H5N4]+. The vibrational absorption bands were identified by infrared spectroscopy and DFT calculations allowed their attribution.

  11. New hypodiphosphates of the alkali metals: Synthesis, crystal structure and vibrational spectra of the hypodiphosphates(IV) M2[(H2P2O6)(H4P2O6)] (M=Rb and Cs)

    NASA Astrophysics Data System (ADS)

    Wu, Peng; Wiegand, Thomas; Eckert, Hellmut; Gjikaj, Mimoza

    2012-10-01

    The new hypodiphosphates(IV) Rb2[(H2P2O6)(H4P2O6)] (1) and Cs2[(H2P2O6)(H4P2O6)] (2) were synthesized by soft chemistry reactions from aqueous solutions of hypophosphoric acid and the corresponding heavy alkali-metal carbonates. Their crystal structures were determined by single crystal X-ray diffraction. Both compounds crystallize isotypic in the triclinic space group P-1 with one formula unit in the unit cell. The structures are built up by discrete (H2P2O6)2- and (H4P2O6) units in staggered conformation for the P2O6 skeleton and the corresponding alkali-metal cations. In the (H2P2O6)2- ion the hydrogen atoms are in a "trans-trans" conformation. O·H-O hydrogen bonds between the (H2P2O6)2- and (H4P2O6) groups consolidate the structures into a three-dimensional network. The FT-Raman and 31P and 1H and MAS NMR spectra of the title compounds have been recorded and interpreted, especially with respect to their assignment to the (H2P2O6)2- and (H4P2O6) groups. Thermogravimetric data of 2 have been interpreted in terms of a thermal decomposition model.

  12. Planar B3S2H3(-) and B3S2H3 clusters with a five-membered B3S2 ring: boron-sulfur hydride analogues of cyclopentadiene.

    PubMed

    Li, Da-Zhi; Li, Rui; Zhang, Li-Juan; Ou, Ting; Zhai, Hua-Jin

    2016-08-21

    Boron clusters can serve as inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs). We present herein, based upon global searches and electronic structural calculations at the B3LYP and CCSD(T) levels, the global-minimum structures of two boron-sulfur hydride clusters: C2v B3S2H3(-) (1, (2)B1) and C2v B3S2H3 (2, (1)A1). Both species are perfectly planar and feature a five-membered B3S2 ring as the structural core, with three H atoms attached terminally to the B sites. Chemical bonding analysis shows that C2v B3S2H3(-) (1) has a delocalized 5π system within a heteroatomic B3S2 ring, analogous to the π bonding in cyclopentadiene, D5h C5H5. The corresponding closed-shell C2v B3S2H3(2-) (3, (1)A1) dianion is only a local minimum. At the single-point CCSD(T) level, it is 5.7 kcal mol(-1) above the chain-like C1 ((1)A) open structure. This situation is in contrast to the cyclopentadienyl anion, C5H5(-), a prototypical aromatic hydrocarbon with a π sextet. The C2v B3S2H3 (2) neutral cluster is readily obtained upon removal of one π electron from C2v B3S2H3(-) (1). The anion photoelectron spectrum of C2v B3S2H3(-) (1) and the infrared absorption spectrum of C2v B3S2H3 (2) are predicted. The C2v B3S2H3(-) (1) species can be stabilized in sandwich-type C2h [(B3S2H3)2Fe](2-) and salt C2h [(B3S2H3)2Fe]Li2 complexes. An intriguing difference is observed between the pattern of π sextet in C2v B3S2H3(2-) (3) dianion and that in cyclopentadienyl anion. The present work also sheds light on the mechanism of structural evolution in the B3S2H3(0/-/2-) series with charge states. PMID:27424889

  13. Cometary implications of recent laboratory experiments on the photochemistry of the C2H and C3H2 radicals

    NASA Technical Reports Server (NTRS)

    Jackson, William M.; Bao, Yihan; Urdahl, Randall S.; Song, Xueyu; Gosine, Jai; Lu, Chi

    1992-01-01

    Recent laboratory results on the photodissociation of the C2H and C3H2 radicals are described. These studies show that the C2 and C3 radicals are produced by the 193 nm photolysis of the C2H and C3H2 radicals, respectively. The quantum state distributions that were determined for the C2 radicals put certain constraints on the initial conditions for any models of the observed C2 cometary spectra. Experimental observations of C2 formed by the 212.8 nm photolysis of C2H are used to calculate a range of photochemical lifetimes for the C2H radical.

  14. First-Principles Electronic Structure Calculations of N2H4 Adsorbed on Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, M.; Tian, W. Q.; Jayanthi, C. S.; Wu, S. Y.

    2008-03-01

    Recent experiments conducted by Desai et al. [1] reveal that single-wall carbon nanotube (SWCNT) networks exposed to N2H4 vapor at various pressures exhibit considerable drop in resistance with respect to the pristine sample. Experimental findings reveal: (i) n-type behavior for the adsorption of N2H4/SWCNT, and (ii) the binding of N2H4 on SWCNT as chemisorption. In the present work, we have performed first-principles electronic structure calculations [2] for the N2H4 adsorbed on the (14, 0) SWCNT, where several orientations for the N2H4 molecule were considered. Calculations for the combined system were performed using 3 unit cells with the DFT/GGA and ultra soft pseudo-potentials. Our calculations reveal: (i) the binding of N2H4 on SWCNT as physisorption, and (ii) the electronic structure of SWCNT to be practically unaltered by the adsorption of N2H4, suggesting that there will not be a dramatic drop in resistance for N2H4/SWCNT. This is in disagreement with the experimental findings. To further understand the experimental observations, we will discuss mechanisms that may alter the binding nature of N2H4 on SWCNT. [1] S. Desai, G. Sumanasekera, et al. (APS, March 2008). [2] G. Kresse and J. Furthmuller, Phys. Rev. B 54, 11169 (1996).

  15. Crystal structure, NMR study, dielectric relaxation and AC conductivity of a new compound [Cd3(SCN)2Br6(C2H9N2)2]n

    NASA Astrophysics Data System (ADS)

    Saidi, K.; Kamoun, S.; Ayedi, H. Ferid; Arous, M.

    2013-11-01

    The crystal structure, the 13C NMR spectroscopy and the complex impedance have been carried out on [Cd3(SCN)2Br6(C2H9N2)2]n. Crystal structure shows a 2D polymeric network built up of two crystallographically independent cadmium atoms with two different octahedral coordinations. This compound exhibits a phase transition at (T=355±2 K) which has been characterized by differential scanning calorimetry (DSC), X-rays powder diffraction, AC conductivity and dielectric measurements. Examination of 13C CP/MAS line shapes shows indirect spin-spin coupling (14N and 13C) with a dipolar coupling constant of 1339 Hz. The AC conductivity of this compound has been carried out in the temperature range 325-376 K and the frequency range from 10-2 Hz to 10 MHz. The impedance data were well fitted to two equivalent electrical circuits. The results of the modulus study reveal the presence of two distinct relaxation processes. One, at low frequency side, is thermally activated due to the ionic conduction of the crystal and the other, at higher frequency side, gradually disappears when temperature reaches 355 K which is attributed to the localized dipoles in the crystal. Moreover, the temperature dependence of DC-conductivity in both phases follows the Arrhenius law and the frequency dependence of σ(ω,T) follows Jonscher's universal law. The near values of activation energies obtained from the conductivity data and impedance confirm that the transport is through the ion hopping mechanism.

  16. Development of microsatellites from Cornus mas L. (Cornaceae) and characterization of genetic diversity of cornelian cherries from China, central Europe, and the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cornelian cherry (Cornus mas L.) is indigenous to central and southeastern Europe and is an ecologically and economically important shrub or small tree. The aim of this study was to develop molecular tools for assessing genetic diversity and provide unique molecular identification of C. mas cultivar...

  17. Who Are the Students Who May Qualify for an Alternate Assessment Based on Modified Academic Achievement Standards (AA-MAS)?: Focus Group Results. Synthesis Report 79

    ERIC Educational Resources Information Center

    Berndt, Sandra; Ebben, Barbara; Kubinski, Eva; Sim, Grant; Liu, Kristin; Lazarus, Sheryl; Thurlow, Martha; Christian, Elizabeth

    2011-01-01

    Beginning in 2007, federal regulations to two major education laws gave state departments of education the option to develop an alternate assessment based on modified achievement standards (AA-MAS) for some students with disabilities. The regulations stated that the AA-MAS was intended for students who were being instructed in the grade-level…

  18. Thermal neutron capture cross sections for 16,171,18O and 2H

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.; Revay, Zs.

    2016-04-01

    Thermal neutron capture γ -ray spectra for 16,17,18O and 2H have been measured with guided cold neutron beams from the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) reactor and the Budapest Research Reactor (BRR) on natural and O,1817 enriched D2O targets. Complete neutron capture γ -ray decay schemes for the 16,17,18O(n ,γ ) reactions were measured. Absolute transition probabilities were determined for each reaction by a least-squares fit of the γ -ray intensities to the decay schemes after accounting for the contribution from internal conversion. The transition probability for the 870.76-keV γ ray from 16O(n ,γ ) was measured as Pγ(871 )=96.6 ±0.5 % and the thermal neutron cross section for this γ ray was determined as 0.164 ±0.003 mb by internal standardization with multiple targets containing oxygen and stoichiometric quantities of hydrogen, nitrogen, and carbon whose γ -ray cross sections were previously standardized. The γ -ray cross sections for the O,1817(n ,γ ) and 2H(n ,γ ) reactions were then determined relative to the 870.76-keV γ -ray cross section after accounting for the isotopic abundances in the targets. We determined the following total radiative thermal neutron cross sections for each isotope from the γ -ray cross sections and transition probabilities; σ0(16O )=0.170 ±0.003 mb; σ0(17O )=0.67 ±0.07 mb; σ0(18O )=0.141 ±0.006 mb; and σ0(2H )=0.489 ±0.006 mb.

  19. Limb-girdle muscular dystrophy 2H and the role of TRIM32.

    PubMed

    Shieh, Perry B; Kudryashova, Elena; Spencer, Melissa J

    2011-01-01

    Limb-girdle muscular dystrophy (LGMD) 2H is a slowly progressive condition characterized by proximal weakness, atrophy, and mildly to moderately raised levels of creatine kinase. Facial weakness, scapular winging, hypertrophied calves, and Achilles tendon contractions are not uncommon and the age of onset ranges between the first and fourth decade. LGMD2H was originally described in the Hutterite population that resides in central Canada and the Dakotas of the USA. LGMD2H was mapped to a specific mutation in the TRIM32 gene and it has subsequently been shown that the same mutation also results in the "sarcotubular myopathy" syndrome, which was described histopathologically. TRIM32 appears to be an E3 ubiquitin ligase, containing the tripartite motif common to this family of proteins (RING finger, B-box, coiled-coil). A few substrates have been identified, including actin and dysbindin. Recent studies have identified additional mutations in the C-terminal region of TRIM32 that result in a dystrophic myopathy. Although TRIM32 appears to be expressed ubiquitously, it is still not clear why certain mutations of TRIM32 would result in a phenotype relatively restricted to skeletal muscle. A mutation in the B-box region of TRIM32 has also been shown to result in a more pleiotropic disorder, Bardet-Biedl Syndrome (BBS11). This disorder is associated with obesity, retinopathy, diabetes, polydactyly, renal abnormalities, learning disability, and hypogenitalism. It is likely that C-terminal mutations in TRIM32 affect the ability of muscle proteins to be degraded by the ubiquitin-proteasome pathway. PMID:21496629

  20. Spectroscopic Line Parameters in the Infrared Bands of CH3CN and C2H6

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy

    2010-10-01

    In this paper, measurements of critical spectroscopic line parameters such as positions, absolute intensities and pressure broadened (self- and N2) half-width coefficients for transitions in the ν4 band of CH3CN (acetonitile, ethanenitrile, methyl cyanide) and the ν9 band of C2H6 (ethane) are presented. CH3CN has been measured by remote sensing in the earth's atmosphere, in comets and in interstellar molecular clouds. It is also a constituent in the atmospheres of Titan, Saturn's largest moon. Likewise, C2H6 is also an important constituent in the atmosphere of earth, the giant planets and comets. The 12- μm(˜720-850 cm-1) emission features of this molecule have been observed in spectra from outer solar system bodies of Jupiter, Saturn, Neptune and Titan. Because of their importance in remote sensing measurements, we recently recorded and analyzed a large number of laboratory infrared absorption spectra of pure and N2-broadened spectra of both these molecular bands. Spectra used in these analyses were recorded using either the Bruker IFS 125HR or the Bruker IFS 120HR FTS located at the Pacific Northwest National Laboratory (PNNL), in Richland Washington. To retrieve the various spectral line parameters, a multispectrum nonlinear least squares fitting algorithm was employed and all spectra belonging to each band were fitted simultaneously. Using this fitting technique, the same spectral regions from multiple spectra were fit all at once to maximize the accuracy of the retrieved parameters. The results obtained from present analyses are briefly discussed. In the case of C2H6 both room- and low temperature (˜210-296 K) spectra were recorded, but results from analyzing only room-temperature spectra will be discussed in this work.

  1. Quinolone-1-(2H)-ones as hedgehog signalling pathway inhibitors.

    PubMed

    Trinh, Trieu N; McLaughlin, Eileen A; Abdel-Hamid, Mohammed K; Gordon, Christopher P; Bernstein, Ilana R; Pye, Victoria; Cossar, Peter; Sakoff, Jennette A; McCluskey, Adam

    2016-07-14

    A series of quinolone-2-(1H)-ones derived from the Ugi-Knoevenagel three- and four-component reaction were prepared exhibiting low micromolar cytotoxicity against a panel of eight human cancer cell lines known to possess the Hedgehog Signalling Pathway (HSP) components, as well as the seminoma TCAM-2 cell line. A focused SAR study was conducted and revealed core characteristics of the quinolone-2-(1H)-ones required for cytotoxicity. These requirements included a C3-tethered indole moiety, an indole C5-methyl moiety, an aliphatic tail or an ester, as well as an additional aromatic moiety. Further investigation in the SAG-activated Shh-LIGHT2 cell line with the most active analogues: 2-(3-cyano-2-oxo-4-phenylquinolin-1(2H)-yl)-2-(1-methyl-1H-indol-3-yl)-N-(pentan-2-yl)acetamide (5), 2-(3-cyano-2-oxo-4-phenylquinolin-1(2H)-yl)-2-(5-methyl-1H-indol-3-yl)-N-(pentan-2-yl)acetamide (23) and ethyl (2-(3-cyano-2-oxo-4-phenylquinolin-1(2H)-yl)-2-(5-methyl-1H-indol-3-yl)acetyl)glycinate (24) demonstrated a down regulation of the HSP via a reduction in Gli expression, and in the mRNA levels of Ptch1 and Gli2. Analogues 5, 23 and 24 returned in cell inhibition values of 11.6, 2.9 and 3.1 μM, respectively, making this new HSP-inhibitor pharmacophore amongst the most potent non-Smo targeted inhibitors thus far reported. PMID:27272335

  2. Volume-discharge formed in SF6 and C2H6 mixtures without preionization

    NASA Astrophysics Data System (ADS)

    Zhang, Ge; Ke, Changjun; Zhang, Shujuan

    2014-11-01

    A new approach to obtain glow discharge in working mixtures of non-chain HF laser has been brought forward. The most advantage of the approach is without pre-ionization, so the contamination of pre-ionization will not happen and the laser equipment is compact and simple. It is found, if the cathode surface is equally rough, we can obtain uniform volume-discharge in SF6 mixtures without any pre-ionization, and dispense with uniform electric field electrode profile. The form of Self-Sustained Volume Discharge (SSVD) is a Self-Initiated Volume Discharge (SIVD). We show here the possibility of obtaining SIVD with a uniform energy deposition in a system of electrodes with non-uniform electric field. Experiments show that, with rough cathode and even anode, a volume discharge is forming in non-uniform electric-field without pre-ionization in SF6 and C2H6 mixtures. At the beginning of the discharge, many diffuse channels attached to bright circular cathode spots, then, diverge towards the anode, with the channels overlapping, form a spatially uniform glow discharge. SIVD has been performed at a total mixture pressure up to 8kPa and energy deposition up to 200J/l. We also report measurements of the V-I characteristics of SIVD with SF6 and C2H6 mixtures at pressure up to about 8kPa. The experimental results indicate that SSVD in SF6 and C2H6 mixtures develops in the form of SIVD is promising for creation of high energy and pulse-periodic HF laser.

  3. An FTIR Calibration for Structural Hydrogen in Feldspars Using 1H MAS NMR

    NASA Astrophysics Data System (ADS)

    Johnson, E. A.; Rossman, G. R.

    2002-05-01

    It is important to know how to determine the speciation and concentration of H in feldspars because this information could be used to determine primary magmatic water activity or to estimate the degree of hydrothermal alteration in igneous rocks. FTIR spectroscopy is sensitive to changes in speciation of hydrogen, and can be calibrated for quantitative determination of H concentration using 1H MAS (magic-angle spinning) NMR spectroscopy. Three pegmatitic albites, one metamorphic albite, three volcanic plagioclases (albite, andesine, and anorthite) and one pegmatite oligoclase were used in this study to provide a range of plagioclase compositions. Two pegmatitic microclines and one sanidine were also studied. Polarized infrared spectra were obtained in the three principal optical directions for each specimen. Samples were prepared for 1H MAS NMR experiments at 12 kHz spinning speed in a dry box, without the use of a liquid grinding aid. A spectrum from anhydrous synthetic corundum was used as a baseline for feldspar NMR spectra. The pegmatitic and metamorphic albites are transparent, but contain submicroscopic fluid inclusions as evidenced by a broad band at 3400 cm-1 and an asymmetric band at 5200 cm-1 in the IR spectra that shift to bands characteristic of ice upon cooling to 77 K. These albites have a very sharp band at 4.7 ppm (relative to TMS) in their NMR spectra consistent with fluid inclusion water. In addition to the broad fluid inclusion band, the pegmatitic albites have sharp bands in the mid-IR similar the OH bands found in quartz. All other plagioclases have broad, anisotropic bands around 3200 cm-1 in the mid-IR and MOH combination stretch-bend bands near 4500 cm-1 in the near-IR, indicative of structural OH. The NMR spectra of these plagioclases have a broad band at 4.7 to 4.9 ppm TMS. The OH vector in plagioclases is preferentially aligned parallel to the a crystallographic axis. The concentration of structural OH in the plagioclases ranges from 50

  4. LyMAS: Predicting Large-scale Lyα Forest Statistics from the Dark Matter Density Field

    NASA Astrophysics Data System (ADS)

    Peirani, Sébastien; Weinberg, David H.; Colombi, Stéphane; Blaizot, Jérémy; Dubois, Yohan; Pichon, Christophe

    2014-03-01

    We describe Lyα Mass Association Scheme (LyMAS), a method of predicting clustering statistics in the Lyα forest on large scales from moderate-resolution simulations of the dark matter (DM) distribution, with calibration from high-resolution hydrodynamic simulations of smaller volumes. We use the "Horizon-MareNostrum" simulation, a 50 h -1 Mpc comoving volume evolved with the adaptive mesh hydrodynamic code RAMSES, to compute the conditional probability distribution P(Fs |δ s ) of the transmitted flux Fs , smoothed (one-dimensionally, 1D) over the spectral resolution scale, on the DM density contrast δ s , smoothed (three-dimensionally, 3D) over a similar scale. In this study we adopt the spectral resolution of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) at z = 2.5, and we find optimal results for a DM smoothing length σ = 0.3 h -1 Mpc (comoving). In its simplest form, LyMAS draws randomly from the hydro-calibrated P(Fs |δ s ) to convert DM skewers into Lyα forest pseudo-spectra, which are then used to compute cross-sightline flux statistics. In extended form, LyMAS exactly reproduces both the 1D power spectrum and one-point flux distribution of the hydro simulation spectra. Applied to the MareNostrum DM field, LyMAS accurately predicts the two-point conditional flux distribution and flux correlation function of the full hydro simulation for transverse sightline separations as small as 1 h -1 Mpc, including redshift-space distortion effects. It is substantially more accurate than a deterministic density-flux mapping ("Fluctuating Gunn-Peterson Approximation"), often used for large-volume simulations of the forest. With the MareNostrum calibration, we apply LyMAS to 10243 N-body simulations of a 300 h -1 Mpc and 1.0 h -1 Gpc cube to produce large, publicly available catalogs of mock BOSS spectra that probe a large comoving volume. LyMAS will be a powerful tool for interpreting 3D Lyα forest data, thereby transforming measurements from BOSS and

  5. LyMAS: Predicting large-scale Lyα forest statistics from the dark matter density field

    SciTech Connect

    Peirani, Sébastien; Colombi, Stéphane; Dubois, Yohan; Pichon, Christophe; Weinberg, David H.; Blaizot, Jérémy

    2014-03-20

    We describe Lyα Mass Association Scheme (LyMAS), a method of predicting clustering statistics in the Lyα forest on large scales from moderate-resolution simulations of the dark matter (DM) distribution, with calibration from high-resolution hydrodynamic simulations of smaller volumes. We use the 'Horizon-MareNostrum' simulation, a 50 h {sup –1} Mpc comoving volume evolved with the adaptive mesh hydrodynamic code RAMSES, to compute the conditional probability distribution P(F{sub s} |δ {sub s}) of the transmitted flux F{sub s} , smoothed (one-dimensionally, 1D) over the spectral resolution scale, on the DM density contrast δ {sub s}, smoothed (three-dimensionally, 3D) over a similar scale. In this study we adopt the spectral resolution of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) at z = 2.5, and we find optimal results for a DM smoothing length σ = 0.3 h {sup –1} Mpc (comoving). In its simplest form, LyMAS draws randomly from the hydro-calibrated P(F{sub s} |δ {sub s}) to convert DM skewers into Lyα forest pseudo-spectra, which are then used to compute cross-sightline flux statistics. In extended form, LyMAS exactly reproduces both the 1D power spectrum and one-point flux distribution of the hydro simulation spectra. Applied to the MareNostrum DM field, LyMAS accurately predicts the two-point conditional flux distribution and flux correlation function of the full hydro simulation for transverse sightline separations as small as 1 h {sup –1} Mpc, including redshift-space distortion effects. It is substantially more accurate than a deterministic density-flux mapping ({sup F}luctuating Gunn-Peterson Approximation{sup )}, often used for large-volume simulations of the forest. With the MareNostrum calibration, we apply LyMAS to 1024{sup 3} N-body simulations of a 300 h {sup –1} Mpc and 1.0 h {sup –1} Gpc cube to produce large, publicly available catalogs of mock BOSS spectra that probe a large comoving volume. LyMAS will be a powerful

  6. Characterization of cation environments in polycrystalline forsterite by Mg-25 MAS, MQMAS, and QCPMG NMR

    SciTech Connect

    Davis, Michael C.; Brouwer, William J.; Lipton, Andrew S.; Gan, Zhehong; Mueller, Karl T.

    2010-11-01

    Forsterite (Mg2SiO4) is a silicate mineral frequently studied in the Earth sciences as it has a simple crystal structure and fast dissolution kinetics (elemental release rates under typical conditions on the order of 10-7 mol/m2/s1). During the dissolution process, spectroscopic techniques are often utilized to augment solution chemical analysis and to provide data for determining reaction mechanisms. Nuclear magnetic resonance (NMR) is able to interrogate the local bonding arrangement and coordination of a particular nuclide to obtain in structural information. Although previous NMR studies have focused on the silicon and oxygen environments in forsterite, studies focusing on the two nonequivalent magnesium environments in forsterite are limited to a few single-crystal studies. In this study, we present the results of 25Mg MAS, MQMAS, and static QCMG experiments performed on a powdered sample of pure synthetic forsterite. We also present spectral fits obtained from simulation software packages, which directly provide quadrupolar parameters for 25Mg nuclei occupying each of the two nonequivalent magnesium sites in the forsterite structure. These results are compared to calculations of the electric field gradient tenor conducted in previous ab initio studies to make definitive assignments correlating each peak to their respective magnesium site in the forsterite structure. Although previous NMR investigations of forsterite have focused on single-crystal samples, we have focused on powdered forsterite as the increased surface area of powdered samples makes them more amenable to laboratory-scale dissolution studies and, ultimately, the products from chemical weathering may be monitored an quantified.

  7. {207}Pb MAS NMR and conductivity identified anomalous phase transition in nanostructured PbF {2}

    NASA Astrophysics Data System (ADS)

    Thangadurai, P.; Ramasamy, S.; Manoharan, P. T.

    2004-02-01

    Lead fluoride, a superionic conductor was prepared in its nanostructured form by Inert Gas Condensation Technique (IGCT) using an Ultra High Vacuum (UHV) chamber. The average grain size was found to be in the range 9 to 43 nm. The existence of mixed phases (α and β-PbF2) was identified using XRD. Solid state 207Pb MAS NMR was carried to average out the dipolar interaction and the resultant isotropic peaks were assigned to the corresponding phases. At high spinning frequencies, one isotropic peak emerged from the contribution of the grain boundary region. The relative intensity of this peak is reduced as the grain size is increased, independent of the concentration of the phases. This is related to the fact that the volume fraction of grain boundary atoms in nanostructured materials increases with the reduction of grain size. The width of the NMR resonance peak is found to be reduced as the grain size goes down. The structural phase transformations were identified at two different temperature regions. The first phase transformation from β to α phase in the annealing temperature range 573 K to 623 K is attributed to some anomalies related to the material microstructure and this has not been reported in earlier literatures. The second phase transformation from α to β in the temperature range 623 K to 673 K is similar to the already reported transformation. Electrical conductivity σ , of the samples was obtained from the complex impedance spectroscopy studies. Conduction species was identified as F- ion through anion vacancies. The magnitude of the conductivity varied according to the dominant phase available when the grain size is higher. But at lower grain sizes below 20 nm, it shows enhanced conductivity that is attributed to the grain size effect. The NMR and conductivity data have jointly supported the anomalous phase transition at the annealing temperature of 623 K.

  8. Experimental investigation of drying characteristics of cornelian cherry fruits ( Cornus mas L.)

    NASA Astrophysics Data System (ADS)

    Ozgen, Filiz

    2015-03-01

    Major target of present paper is to investigate the drying kinetics of cornelian cherry fruits ( Cornus mas L.) in a convective dryer, by varying the temperature and the velocity of drying air. Freshly harvested fruits are dried at drying air temperature of 35, 45 and 55 °C. The considered drying air velocities are V air = 1 and 1.5 m/s for each temperature. The required drying time is determined by taking into consideration the moisture ratio measurements. When the moisture ratio reaches up to 10 % at the selected drying air temperature, then the time is determined ( t = 40-67 h). The moisture ratio, fruit temperature and energy requirement are presented as the functions of drying time. The lowest drying time (40 h) is obtained when the air temperature is 55 °C and air velocity is 1.5 m/s. The highest drying time (67 h) is found under the conditions of 35 °C temperature and 1 m/s velocity. Both the drying air temperature and the air velocity significantly affect the required energy for drying system. The minimum amount of required energy is found as 51.12 kWh, at 55 °C and 1 m/s, whilst the maximum energy requirement is 106.7 kWh, at 35 °C and 1.5 m/s. It is also found that, air temperature significantly influences the total drying time. Moreover, the energy consumption is decreasing with increasing air temperature. The effects of three parameters (air temperature, air velocity and drying time) on drying characteristics have also been analysed by means of analysis of variance method to show the effecting levels. The experimental results have a good agreement with the predicted ones.

  9. Mas-related G-protein–coupled receptors inhibit pathological pain in mice

    PubMed Central

    Guan, Yun; Liu, Qin; Tang, Zongxiang; Raja, Srinivasa N.; Anderson, David J.; Dong, Xinzhong

    2010-01-01

    An important objective of pain research is to identify novel drug targets for the treatment of pathological persistent pain states, such as inflammatory and neuropathic pain. Mas-related G-protein–coupled receptors (Mrgprs) represent a large family of orphan receptors specifically expressed in small-diameter nociceptive primary sensory neurons. To determine the roles of Mrgprs in persistent pathological pain states, we exploited a mouse line in which a chromosomal locus spanning 12 Mrgpr genes was deleted (KO). Initial studies indicated that these KO mice show prolonged mechanical- and thermal-pain hypersensitivity after hind-paw inflammation compared with wild-type littermates. Here, we show that this mutation also enhances the windup response of dorsal-horn wide dynamic-range neurons, an electrophysiological model for the triggering of central pain sensitization. Deletion of the Mrgpr cluster also blocked the analgesic effect of intrathecally applied bovine adrenal medulla peptide 8–22 (BAM 8–22), an MrgprC11 agonist, on both inflammatory heat hyperalgesia and neuropathic mechanical allodynia. Spinal application of bovine adrenal medulla peptide 8–22 also significantly attenuated windup in wild-type mice, an effect eliminated in KO mice. These data suggest that members of the Mrgpr family, in particular MrgprC11, may constitute an endogenous inhibitory mechanism for regulating persistent pain in mice. Agonists for these receptors may, therefore, represent a class of antihyperalgesics for treating persistent pain with minimal side effects because of the highly specific expression of their targets. PMID:20724664

  10. Charge transfer in energetic Li2+-H and He+-He+ collisions

    NASA Astrophysics Data System (ADS)

    Mančev, I.

    2009-02-01

    The total cross sections for charge transfer in Li2+-H and He+-He+ collisions have been calculated, using the four body first Born approximation with correct boundary conditions (CB1-4B) and four body continuum distorted wave method (CDW-4B) in the energy range 10-5000 keV/amu. The role of dynamic electron correlations is examined as a function of the impact energy. The present results call for additional experimental data at higher impact energies than presently available.

  11. Development of homotopy algorithms for fixed-order mixed H2/H(infinity) controller synthesis

    NASA Technical Reports Server (NTRS)

    Whorton, M.; Buschek, H.; Calise, A. J.

    1994-01-01

    A major difficulty associated with H-infinity and mu-synthesis methods is the order of the resulting compensator. Whereas model and/or controller reduction techniques are sometimes applied, performance and robustness properties are not preserved. By directly constraining compensator order during the optimization process, these properties are better preserved, albeit at the expense of computational complexity. This paper presents a novel homotopy algorithm to synthesize fixed-order mixed H2/H-infinity compensators. Numerical results are presented for a four-disk flexible structure to evaluate the efficiency of the algorithm.

  12. Positron measurements in 2H-TaSe/sub 2/ crystals

    SciTech Connect

    Jean, Y.C.; Fluss, M.J.

    1985-01-01

    Temperature-dependent positron annihilation lifetime and Doppler broadening experiments are reported on single crystals of 2H-TaSe/sub 2/ to search for effects from known charge-density-wave (CDW) phase transitions. The positron lifetime in the perfect lattice and in positron trapping sites were found to be 0.173 and 0.378 ns, respectively. The apparent activation energy for the thermally generated trapping sites was found to be 0.12 eV. Doppler broadening spectra exhibited no response to the known CDW phase transitions, nor any significant overall anisotropy in their temperature dependence.

  13. Characterization Results for the 2014 HTF 3H & 2H Evaporator Overhead Samples

    SciTech Connect

    Washington, A.

    2015-05-11

    This report tabulates the radiochemical analysis of the 3H and 2H evaporator overhead samples for 137Cs, 90Sr, and 129I to meet the requirements in the Effluent Treatment Project (ETP) Waste Acceptance Criteria (WAC) (rev. 6). This report identifies the sample receipt date, preparation method, and analysis performed in the accumulation of the listed values. All data was found to be within the ETP WAC (rev. 6) specification for the Waste Water Collection Tanks (WWCT).

  14. Low-temperature solid-state phase transformations in 2H silicon carbide.

    NASA Technical Reports Server (NTRS)

    Powell, J. A.; Will, H. A.

    1972-01-01

    Study of the phase transformations taking place in 2H SiC single crystals at temperatures as low as 400 C. Some crystals transformed to a structure with one-dimensional disorder along the crystal c axis. Others transformed to a faulted cubic/6H structure. The transformation is time and temperature dependent, and is greatly enhanced by dislocations. The transformation takes place by means of a slip process perpendicular to the c axis. Cubic SiC crystals were observed to undergo a solid-state transformation above 1400 C.

  15. Mid-Infrared Spectrum of the Atmospherically Significant N2-H2O Complex

    NASA Astrophysics Data System (ADS)

    Springer, Sean D.; McElmurry, Blake A.; Lucchese, Robert R.; Bevan, John W.; Coudert, L. H.

    2014-06-01

    Rovibrational transitions associated with tunneling states in the vibration of the N2-H2O complex have been recorded using a supersonic jet quantum cascade laser spectrometer at 6.2μm. Analysis of the resulting spectra is facilitated by incorporating fits of previously recorded microwave and submillimeter data accounting for Coriolis coupling to obtain the levels of the ground vibrational state. The results are then used to confirm assignment of the νb{3} vibration and explore the nature of tunneling dynamics in associated vibrationally excited states of the complex.

  16. Rate constants for reactions between atmospheric reservoir species. 2. H sub 2 O

    SciTech Connect

    Hatakeyama, Shiro; Leu, Mingtaun )

    1989-07-27

    The kinetics of the reactions of H{sub 2}O with ClONO{sub 2}, N{sub 2}O{sub 5}, O{sub 3}, and COCl{sub 2} have been investigated by using a large-volume static cell and a Fourier transform infrared spectrometer at 296 K. Upper limits for the homogeneous gas-phase reaction rate constants of the ClONO{sub 2} + H{sub 2}O, N{sub 2}O{sub 5} + H{sub 2}O, O{sub 3} + H{sub 2}O, and COCl{sub 2} + H{sub 2}O reactions were found to be 3.4 {times} 10{sup {minus}21}, 2.8 {times} 10{sup {minus}21}, 1.1 {times} 10{sup {minus}22}, and 1.2 {times} 10{sup {minus}23}, respectively (all in units of cm{sup 3} s{sup {minus}1}), based on the observed decay rates of ClONO{sub 2}, N{sub 2}O{sub 5}, O{sub 3}, and COCl{sub 2}. Product analyses gave 0.82 {plus minus} 0.07 for the yield of HNO{sub 3} in the ClONO{sub 2} + H{sub 2}O {yields} HOCl + HNO{sub 3} reaction and 1.1 {plus minus} 0.3 for the yield of HNO{sub 3} from the N{sub 2}O{sub 5} + H{sub 2}O {yields} 2HNO{sub 3} reaction. The quoted error represents one standard deviation of the measurement. An attempt was also made to monitor possible reaction products such as H{sub 2}O{sub 2} for the O{sub 3} + H{sub 2}O reaction, and CO{sub 2} or HCl for the COCl{sub 2} + H{sub 2}O reaction. These results may be important in the elucidation of the springtime Antarctic ozone depletion over the past decade. The implication for NO{sub x} chemistry in the nighttime troposphere based on their results of the N{sub 2}O{sub 5} + H{sub 2}O reaction will be discussed.

  17. The quasielastic 2H(e,e'p)n reaction at high recoil momenta

    SciTech Connect

    D. Crovelli; Konrad Aniol; Javier Gomez; John LeRose; Arunava Saha; Paul Ulmer; Vina Punjabi; Richard Lindgren; Charles Perdrisat; David Meekins; Joseph Mitchell; Mark Jones; Robert Michaels; Bogdan Wojtsekhowski; Hartmuth Arenhoevel; Michael Finn; Jens-Ole Hansen; Riad Suleiman; Kevin Fissum; Sergey Malov; Cornelis De Jager; Cornelis de Jager; Rikki Roche; Michael Kuss; Eugene Chudakov; Sabine Jeschonnek; Franck Sabatie; Luminita Todor; Meihua Liang; Olivier Gayou; Jian-Ping Chen

    2001-11-01

    The 2H(e,e'p)n cross section was measured in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) in quasielastic kinematics (x=0.96) at a four-momentum transfer squared, Q{sup 2}=0.67 (GeV/c){sup 2}. The experiment was performed in fixed electron kinematics for recoil momenta from zero to 550 MeV/c. Though the measured cross section deviates by 1-2 sigma from a state-of-the-art calculation at low recoil momenta, it agrees at high recoil momenta where final state interactions (FSI) are predicted to be large.

  18. Palladium-Catalyzed Synthesis of 2-Aryl-2H-Benzotriazoles from Azoarenes and TMSN3.

    PubMed

    Khatun, Nilufa; Modi, Anju; Ali, Wajid; Patel, Bhisma K

    2015-10-01

    Substrate-directed ortho C-H amination of azoarenes using TMSN3 as the source of nitrogen leading to the synthesis of 2-aryl-2H-benzotriazoles has been accomplished with the help of Pd/TBHP combinations. An intermolecular o-azidation (C-N bond formation) followed by an intramolecular N-N bond formation via nucleophilic attack of one of the azo nitrogen onto the o-azide nitrogen leads to cyclization with the expulsion of N2. PMID:26372371

  19. Early Gravitropic Events in Roots of Arabidopsis: Ca(2+)H(+) Fluxes in the Columella Cells

    NASA Technical Reports Server (NTRS)

    Feldman, Lewis

    2003-01-01

    Despite the wealth of information derived from physiological approaches, molecular mechanisms for sensing and responding to gravity in plants remain largely uncharacterized. Roots of higher plants offer many advantages for studying the sensing and responding phases. In roots, gravisensing occurs in specialized cells, the columella cells in which earlier studies have indicated an involvement of the cytoskeleton, Ca(2+), H(+) and auxin in processing the gravity signal. The overall goal of this project was to characterize gravity-stimulated Ca(2+) and H(+) fluxes in the columella cells of a model plant Arabidopsis thaliana and to define their regulation. For this work we used intact Arabidopsis roots.

  20. Crystal structure of 2-oxo-N′-phenyl-2H-chromene-3-carbohydrazide

    PubMed Central

    Mague, Joel T.; Mohamed, Shaaban K.; Akkurt, Mehmet; Younes, Sabry H. H.; Albayati, Mustafa R.

    2015-01-01

    In the title compound, C16H12N2O3, the 2H-chromene moiety is essentially planar, with an r.m.s. deviation of the nine constituent atoms from the mean plane of 0.0093 Å, and makes a dihedral angle of 76.84 (3)° with the pendant phenyl ring. An intra­molecular N—H⋯O hydrogen bond helps to determine the conformation of the side chain. In the crystal, N—H⋯O and N—H⋯N hydrogen bonds link the mol­ecules, forming [100] chains. PMID:26870466

  1. Phthalazin-1(2H)-one–picric acid (1/1)

    PubMed Central

    Yathirajan, H. S.; Narayana, B.; Swamy, M. T.; Sarojini, B. K.; Bolte, Michael

    2008-01-01

    The geometric parameters of the title compound, C8H6N2O·C6H3N3O7, are in the usual ranges. The three nitro groups are almost coplanar with the aromatic picrate ring [dihedral angles 10.2 (2)°, 7.62 (16) and 8.08 (17)°]. The mol­ecular conformation of the picric acid is stabilized by an intra­molecular O—H⋯O hydrogen bond. The phthalazin-1(2H)-one mol­ecules are connected via N—H⋯O hydrogen bonds, forming centrosymmetric dimers. PMID:21200682

  2. Quantum effects in the scattering of argon from 2H-W(100)

    SciTech Connect

    Schweizer, E. K.; Rettner, C. T.

    1989-06-26

    Diffraction has been observed in the scattering of Ar from a 2H-W(100) surface. Results are found to be consistent with an effective surface corrugation amplitude of about 0.05 A, which is similar to values obtained for He and Ne diffraction from this surface. The temperature dependence yields a surface Debye temperature of /similar to/400 K. We also find that the shape and behavior of surface scattering rainbows observed in this system are best accounted for by a quantum mechanical treatment of the Ar-surface interaction.

  3. Probing anisotropic interaction potentials of unsaturated hydrocarbons with He*(2 3S) metastable atom: Attractive-site preference of σ-direction in C2H2 and π-direction in C2H4

    NASA Astrophysics Data System (ADS)

    Horio, Takuya; Hatamoto, Takuro; Maeda, Satoshi; Kishimoto, Naoki; Ohno, Koichi

    2006-03-01

    State-resolved collision energy dependence of Penning ionization cross sections of acetylene (C2H2) and ethylene (C2H4) with He*(2S3) metastable atoms was observed in a wide collision energy range from 20to350meV. A recently developed discharge nozzle source with a liquid N2 circulator was employed for the measurements in the low-energy range from 20to80meV. Based on classical trajectory calculations for the energy dependence of the partial ionization cross sections, anisotropic potential energy surfaces for the present systems were obtained by optimizing ab initio model potentials for the chemically related systems Li +C2H2 and C2H4. In the case of C2H2, the global minimum was found to be located around the H atom along the molecular axis with a well depth of 48meV (ca. 1.1kcal/mol). On the other hand, a dominant attractive well with a depth of 62meV (ca. 1.4kcal/mol) was found in the πCC electron region of C2H4. These findings were discussed in connection with orbital interactions between molecular orbitals of the target molecules and atomic orbitals of the metastable atom. It is concluded that σ-type unoccupied molecular orbitals of C2H2 and a πCC-type highest occupied molecular orbital of C2H4 play a significant role for the attractive-site preference of σ direction in C2H2 and π direction in C2H4, respectively.

  4. Shrimp Serine Proteinase Homologues PmMasSPH-1 and -2 Play a Role in the Activation of the Prophenoloxidase System

    PubMed Central

    Jearaphunt, Miti; Amparyup, Piti; Sangsuriya, Pakkakul; Charoensapsri, Walaiporn; Senapin, Saengchan; Tassanakajon, Anchalee

    2015-01-01

    Melanization mediated by the prophenoloxidase (proPO) activating system is a rapid immune response used by invertebrates against intruding pathogens. Several masquerade-like and serine proteinase homologues (SPHs) have been demonstrated to play an essential role in proPO activation in insects and crustaceans. In a previous study, we characterized the masquerade-like SPH, PmMasSPH1, in the black tiger shrimp Penaeus monodon as a multifunctional immune protein based on its recognition and antimicrobial activity against the Gram-negative bacteria Vibrio harveyi. In the present study, we identify a novel SPH, known as PmMasSPH2, composed of an N-terminal clip domain and a C-terminal SP-like domain that share high similarity to those of other insect and crustacean SPHs. We demonstrate that gene silencing of PmMasSPH1 and PmMasSPH2 significantly reduces PO activity, resulting in a high number of V. harveyi in the hemolymph. Interestingly, knockdown of PmMasSPH1 suppressed not only its gene transcript but also other immune-related genes in the proPO system (e.g., PmPPAE2) and antimicrobial peptides (e.g., PenmonPEN3, PenmonPEN5, crustinPm1 and Crus-likePm). The PmMasSPH1 and PmMasSPH2 also show binding activity to peptidoglycan (PGN) of Gram-positive bacteria. Using a yeast two-hybrid analysis and co-immunoprecipitation, we demonstrate that PmMasSPH1 specifically interacted with the final proteinase of the proPO cascade, PmPPAE2. Furthermore, the presence of both PmMasSPH1 and PmPPAE2 enhances PGN-induced PO activity in vitro. Taken together, these results suggest the importance of PmMasSPHs in the activation of the shrimp proPO system. PMID:25803442

  5. Recent progress on the 27Al+ ion optical clock

    NASA Astrophysics Data System (ADS)

    Xu, Z. T.; Yuan, W. H.; Zeng, X. Y.; Che, H.; Shi, X. H.; Deng, K.; Zhang, J.; Lu, Z. H.

    2016-06-01

    An aluminium ion optical clock is under development at Huazhong University of Science and Technology. The 25Mg+ ion is chosen as logic ion to sympathetically cool an Al+ ion and to detect its states. The 25Mg+ ion is cooled to the motional ground state through Raman sideband cooling as the first step for quantum logic spectroscopy. Ultra-stable lasers for the interrogation of the clock transition are developed. The instability of the laser beat frequency is 1.2 x 10-15 at 1 s, which is close to the thermal noise limit of the reference cavity.

  6. Mining the Brassica oleracea genome for Q-type C2H2 zinc finger transcription factor proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Q-type zinc finger proteins have been studied in several plant species and have been associated with response to stress. A whole genome analysis of Arabidopsis identified 176 putative C2H2 transcription factors (TF). Q-type C2H2 TFs containing the QALGGH motif and are a subset of these. In Arabidops...

  7. EVIDENCE OF DIFFERENTIAL PH REGULATION OF THE ARABIDOPSIS VACUOLAR CA2+/H+ ANTIPORTERS CAX1 AND CAX2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Arabidopsis Ca(2+)/H(+) antiporters cation exchanger (CAX) 1 and 2 utilise an electrochemical gradient to transport Ca(2+) into the vacuole to help mediate Ca(2+) homeostasis. Previous whole plant studies indicate that activity of Ca(2+)/H(+) antiporters is regulated by pH. However, the pH regul...

  8. Advanced Low-Cost O2/H2 Engines for the SSTO Application

    NASA Technical Reports Server (NTRS)

    Goracke, B. David; Levack, Daniel J. H.; Nixon, Robert F.

    1994-01-01

    The recent NASA Access to Space study examined future Earth to orbit (ETO) transportation needs and fleets out to 2030. The baseline in the option 3 assessment was a single stage to orbit (SSTO) vehicle. A study was conducted to assess the use of new advanced low cost O2/H2 engines for this SSTO application. The study defined baseline configurations and ground rules and defined six engine cycles to explore engine performance. The cycles included an open cycle, and a series of closed cycles with varying abilities to extract energy from the propellants to power he turbomachinery. The cycles thus varied in the maximum chamber pressure they could reach and in their weights at any given chamber pressure. The weight of each cycle was calculated for two technology levels versus chamber pressure up to the power limit of the cycle. The performance in the SSTO mission was then modeled using the resulting engine weights and specific impulse performance using the Access to Space option 3 vehicle. The results showed that new O2/H2 engines are viable and competitive candidates for the SSTO application using chamber pressures of 4,000 psi.

  9. NO Removal in High Pressure Plasmas of N_2/H_2O/NO Mixtures

    NASA Astrophysics Data System (ADS)

    Fresnet, F.; Baravian, G.; Magne, L.; Pasquiers, S.; Postel, C.; Puech, V.; Rousseau, A.

    2001-10-01

    Influence of H_2O on NO removal has been studied using a homogeneous photo-triggered discharge with a time resolved LIF measurement of the NO density, in N_2/H_2O/NO mixtures at 460 mbar. The H_2O maximum concentration was 2.5 was between 70 and 160 J/l. Measurement of NO density has been performed up to 180 µs after the current pulse excitation of short duration, 50 ns. Kinetic analysis has been made using a self-consistent 0D-discharge model. NO is in great part dissociated, in N_2/NO, through collisions with the excited singlet states of N_2. We have previously shown that addition of ethene induces de-excitation of these states, leading to a decrease of the NO removal ( F. Fresnet, G. Baravian, L. Magne, S. Pasquiers, C. Postel, V. Puech, A. Rousseau, Appl. Phys. Lett., 77 (2000) 4118.). Similar processes take place when C_2H4 is replaced by H_2O. The value of the rate constant for collision of singlet states with water, 3.10-10 cm^3 s-1, is obtained from our study.

  10. Refinements in an Mg/MgH2/H2O-Based Hydrogen Generator

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew; Huang, Yuhong

    2010-01-01

    Some refinements have been conceived for a proposed apparatus that would generate hydrogen (for use in a fuel cell) by means of chemical reactions among magnesium, magnesium hydride, and steam. The refinements lie in tailoring spatial and temporal distributions of steam and liquid water so as to obtain greater overall energy-storage or energy-generation efficiency than would otherwise be possible. A description of the prior art is prerequisite to a meaningful description of the present refinements. The hydrogen-generating apparatus in question is one of two versions of what was called the "advanced hydrogen generator" in "Fuel-Cell Power Systems Incorporating Mg-Based H2 Generators" (NPO-43554), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 52. To recapitulate: The apparatus would include a reactor vessel that would be initially charged with magnesium hydride. The apparatus would exploit two reactions: The endothermic decomposition reaction MgH2-->Mg + H2, which occurs at a temperature greater than or equal to 300 C, and The exothermic oxidation reaction MgH2 + H2O MgO + 2H2, which occurs at a temperature greater than or equal to 330 C.

  11. Theoretical study of radiative electron attachment to CN, C2H, and C4H radicals.

    PubMed

    Douguet, Nicolas; Fonseca dos Santos, S; Raoult, Maurice; Dulieu, Olivier; Orel, Ann E; Kokoouline, Viatcheslav

    2015-06-21

    A first-principle theoretical approach to study the process of radiative electron attachment is developed and applied to the negative molecular ions CN(-), C4H(-), and C2H(-). Among these anions, the first two have already been observed in the interstellar space. Cross sections and rate coefficients for formation of these ions by direct radiative electron attachment to the corresponding neutral radicals are calculated. For the CN molecule, we also considered the indirect pathway, in which the electron is initially captured through non-Born-Oppenheimer coupling into a vibrationally resonant excited state of the anion, which then stabilizes by radiative decay. We have shown that the contribution of the indirect pathway to the formation of CN(-) is negligible in comparison to the direct mechanism. The obtained rate coefficients for the direct mechanism at 30 K are 7 × 10(-16) cm(3)/s for CN(-), 7 × 10(-17) cm(3)/s for C2H(-), and 2 × 10(-16) cm(3)/s for C4H(-). These rates weakly depend on temperature between 10 K and 100 K. The validity of our calculations is verified by comparing the present theoretical results with data from recent photodetachment experiments. PMID:26093561

  12. Pumping Ca2+ up H+ gradients: a Ca2(+)-H+ exchanger without a membrane.

    PubMed

    Swietach, Pawel; Leem, Chae-Hun; Spitzer, Kenneth W; Vaughan-Jones, Richard D

    2014-08-01

    Cellular processes are exquisitely sensitive to H+ and Ca2+ ions because of powerful ionic interactions with proteins. By regulating the spatial and temporal distribution of intracellular [Ca2+] and [H+], cells such as cardiac myocytes can exercise control over their biological function. A well-established paradigm in cellular physiology is that ion concentrations are regulated by specialized, membrane-embedded transporter proteins. Many of these couple the movement of two or more ionic species per transport cycle, thereby linking ion concentrations among neighbouring compartments. Here, we compare and contrast canonical membrane transport with a novel type of Ca(2+)-H+ coupling within cytoplasm, which produces uphill Ca2+ transport energized by spatial H+ ion gradients, and can result in the cytoplasmic compartmentalization of Ca2+ without requiring a partitioning membrane. The mechanism, demonstrated in mammalian myocytes, relies on diffusible cytoplasmic buffers, such as carnosine, homocarnosine and ATP, to which Ca2+ and H+ ions bind in an apparently competitive manner. These buffer molecules can actively recruit Ca2+ to acidic microdomains, in exchange for the movement of H+ ions. The resulting Ca2+ microdomains thus have the potential to regulate function locally. Spatial cytoplasmic Ca(2+)-H+ exchange (cCHX) acts like a 'pump' without a membrane and may be operational in many cell types. PMID:24514908

  13. CCQE, 2p2h excitations and ν—energy reconstruction

    SciTech Connect

    Nieves, J.; Simo, I. Ruiz; Sánchez, F.; Vacas, M. J. Vicente

    2015-05-15

    We analyze the MiniBooNE muon neutrino CCQE-like dσ/dT{sub μ} d cos θ{sub μ} data using a theoretical model that, among other nuclear effects, includes RPA correlations and 2p2h (multinucleon) mechanisms. These corrections turn out to be essential for the description of the data. We find that MiniBooNE CCQE-like data are fully compatible with former determinations of the nucleon axial mass M{sub A} ∼ 1.05 GeV. This is in sharp contrast with several previous analysis where anomalously large values of M{sub A} ∼ 1.4 GeV have been suggested. We also show that because of the the multinucleon mechanism effects, the algorithm used to reconstruct the neutrino energy is not adequate when dealing with quasielastic-like events. Finally, we analyze the MiniBooNE unfolded cross section, and show that it exhibits an excess (deficit) of low (high) energy neutrinos, which is an artifact of the unfolding process that ignores 2p2h mechanisms.

  14. Orientational landscapes of peptides in membranes: prediction of (2)H NMR couplings in a dynamic context.

    PubMed

    Esteban-Martín, Santi; Giménez, Diana; Fuertes, Gustavo; Salgado, Jesús

    2009-12-01

    Unlike soluble proteins, membrane polypeptides face an anisotropic milieu. This imposes restraints on their orientation and provides a reference that makes structure prediction tractable by minimalistic thermodynamic models. Here we use this framework to build orientational distributions of monomeric membrane-bound peptides and to predict their expected solid-state (2)H NMR quadrupolar couplings when labeled at specific side chain positions. Using a complete rigid-body sampling of configurations relative to an implicit lipid membrane, peptide free energy landscapes are calculated. This allows us to obtain probability distributions of the peptide tilt, azimuthal rotation, and depth of membrane insertion. The orientational distributions are broad and originate from an interplay among the three relevant rigid-body degrees of freedom, which allows population of multiple states in shallow free energy minima. Remarkably, only when the orientational distributions are taken into account do we obtain a close correlation between predicted (2)H NMR splittings and values measured in experiments. Such a good correlation is not seen with splittings calculated from single configurations, being either the averaged or the lowest free energy state, showing there are distributions, rather than single structures, that best define the peptide-membrane systems. Moreover, we propose that these distributions contribute to the understanding of the rigid-body dynamics of the system. PMID:19860438

  15. VUV photoionization cross sections of HO2, H2O2, and H2CO.

    PubMed

    Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

    2015-02-26

    The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra. PMID:25621533

  16. Functionalization of liquid-exfoliated two-dimensional 2H-MoS2.

    PubMed

    Backes, Claudia; Berner, Nina C; Chen, Xin; Lafargue, Paul; LaPlace, Pierre; Freeley, Mark; Duesberg, Georg S; Coleman, Jonathan N; McDonald, Aidan R

    2015-02-23

    Layered two-dimensional (2D) inorganic transition-metal dichalchogenides (TMDs) have attracted great interest as a result of their potential application in optoelectronics, catalysis, and medicine. However, methods to functionalize and process such 2D TMDs remain scarce. We have established a facile route towards functionalized layered MoS2 . We found that the reaction of liquid-exfoliated 2D MoS2 , with M(OAc)2 salts (M=Ni, Cu, Zn; OAc=acetate) yielded functionalized MoS2 -M(OAc)2 materials. Importantly, this method furnished the 2H-polytype of MoS2 which is a semiconductor. X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT-IR), and thermogravimetric analysis (TGA) provide strong evidence for the coordination of MoS2 surface sulfur atoms to the M(OAc)2 salt. Interestingly, functionalization of 2H-MoS2 allows for its dispersion/processing in more conventional laboratory solvents. PMID:25612324

  17. Trojan Horse particle invariance for 2H(d,p)3H reaction: a detailed study

    NASA Astrophysics Data System (ADS)

    Pizzone, R. G.; Spitaleri, C.; Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L.; La Cognata, M.; Lamia, L.; Rinollo, A.; Spartá, R.; Tumino, A.

    2014-03-01

    In the last decades the Trojan Horse method has played a crucial role for the measurement of several charged particle induced reactions cross sections of astrophysical interest. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The Trojan Horse nucleus invariance for the binary d(d,p)t reaction was therefore tested using the quasi free 2H(6Li, pt)4He and 2H(3He,pt)H reactions after 6Li and 3He break-up, respectively. The astrophysical S(E)-factor for the d(d,p)t binary process was then extracted in the framework of the Plane Wave Approximation applied to the two different break-up schemes. The obtained results are compared with direct data as well as with previous indirect investigations. The very good agreement confirms the applicability of the plane wave approximation and suggests the independence of binary indirect cross section on the chosen Trojan Horse nucleus also for the present case.

  18. Optimization of intermolecular potential parameters for the CO2/H2O mixture.

    PubMed

    Orozco, Gustavo A; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

    2014-10-01

    Monte Carlo simulations in the Gibbs ensemble were used to obtain optimized intermolecular potential parameters to describe the phase behavior of the mixture CO2/H2O, over a range of temperatures and pressures relevant for carbon capture and sequestration processes. Commonly used fixed-point-charge force fields that include Lennard-Jones 12-6 (LJ) or exponential-6 (Exp-6) terms were used to describe CO2 and H2O intermolecular interactions. For force fields based on the LJ functional form, changes of the unlike interactions produced higher variations in the H2O-rich phase than in the CO2-rich phase. A major finding of the present study is that for these potentials, no combination of unlike interaction parameters is able to adequately represent properties of both phases. Changes to the partial charges of H2O were found to produce significant variations in both phases and are able to fit experimental data in both phases, at the cost of inaccuracies for the pure H2O properties. By contrast, for the Exp-6 case, optimization of a single parameter, the oxygen-oxygen unlike-pair interaction, was found sufficient to give accurate predictions of the solubilities in both phases while preserving accuracy in the pure component properties. These models are thus recommended for future molecular simulation studies of CO2/H2O mixtures. PMID:25198539

  19. Mobility of Core Water in Bacillus subtilis Spores by 2H NMR

    NASA Astrophysics Data System (ADS)

    Kaieda, Shuji; Setlow, Barbara; Setlow, Peter; Halle, Bertil

    2013-11-01

    Bacterial spores in a metabolically dormant state can survive long periods without nutrients under extreme environmental conditions. The molecular basis of spore dormancy is not well understood, but the distribution and physical state of water within the spore is thought to play an important role. Two scenarios have been proposed for the spore's core region, containing the DNA and most enzymes. In the gel scenario, the core is a structured macromolecular framework permeated by mobile water. In the glass scenario, the entire core, including the water, is an amorphous solid and the quenched molecular diffusion accounts for the spore's dormancy and thermal stability. Here, we use $^2$H magnetic relaxation dispersion to selectively monitor water mobility in the core of Bacillus subtilis spores in the presence and absence of core Mn$^{2+}$ ions. We also report and analyze the solid-state $^2$H NMR spectrum from these spores. Our NMR data clearly support the gel scenario with highly mobile core water (~ 25 ps average rotational correlation time). Furthermore, we find that the large depot of manganese in the core is nearly anhydrous, with merely 1.7 % on average of the maximum sixfold water coordination.

  20. Redetermination of [EuCl2(H2O)6]Cl

    PubMed Central

    Tambornino, Frank; Bielec, Philipp; Hoch, Constantin

    2014-01-01

    The crystal structure of the title compound, hexa­aqua­dichlorido­europium(III) chloride, was redetermined with modern crystallographic methods. In comparison with the previous study [Lepert et al. (1983 ▶). Aust. J. Chem. 36, 477–482], it could be shown that the atomic coordinates of some O atoms had been confused and now were corrected. Moreover, it was possible to freely refine the positions of the H atoms and thus to improve the accurracy of the crystal structure. [EuCl2(H2O)6]Cl crystallizes with the GdCl3·6H2O structure-type, exhibiting discrete [EuCl2(H2O)6]+ cations as the main building blocks. The main blocks are linked with isolated chloride anions via O—H⋯Cl hydrogen bonds into a three-dimensional framework. The Eu3+ cation is located on a twofold rotation axis and is coordinated in the form of a Cl2O6 square anti­prism. One chloride anion coordinates directly to Eu3+, whereas the other chloride anion, situated on a twofold rotation axis, is hydrogen bonded to six octa­hedrally arranged water mol­ecules. PMID:24940187